Standard High-K metal gate (HKMG) CMOS technologies fabricated using the replacement metal gate (RMG), also known as gate-last, integration flow, are susceptible to oxygen ingress into the high-K gate dielectric layer and oxygen diffusion into the gate dielectric and semiconductor channel region. The oxygen at the gate dielectric and semiconductor channel interface induces unwanted oxide regrowth that results in an effective oxide thickness increase, and transistor threshold voltage shifts, both of which are highly variable and degrade semiconductor chip performance. By introducing silicon nitride deposited at low temperature, after the metal gate formation, the oxygen ingress and gate dielectric regrowth can be avoided, and a high semiconductor chip performance is maintained.

High-K dielectric with Metal Gate electrodes (HKMG) has been proven to be one of the most critical innovations that allows further gate thickness scaling, which in turn enables the active channel length scaling and the overall performance boost in advanced CMOS technology. Furthermore, the Replacement Gate (RMG) integration flow for HKMG provides additional advantage in terms of thermal budget control. However, in a typical HKMG RMG flow, gate dielectric, including the high-K gate can become exposed after the metal gate CMP process. This can provides an oxygen ingress path and lead to oxide regrowth at gate channel interface during the subsequent Middle of Line (MOL) dielectric deposition and Back End of the Line (BEOL) processing. The oxide regrowth increases the effective dielectric thickness and shifts the transistor threshold voltage, both of which can cause severe device degradation in terms of performance and variability. Thus, the oxygen ingress and regrowth at high-K gate dielectric to semiconductor channel interface should be avoided.
In the prior art, after the metal-gate CMP is completed, the next layer, usually silicon nitride, is typically deposited at temperatures high enough (>500° C.) that the exposed high-K gate dielectric material can absorb any oxygen present during the deposition process, and transport the oxygen towards the gate dielectric to channel interface region, where the oxygen causes an unwanted regrowth. The deposition temperature is important because higher temperatures increase the absorption and diffusion of oxygen into the high-K gate dielectric, towards the gate dielectric to channel interface.
FIGS. 1 to 8 illustrate prior art for High-K Metal Gate (HKMG) Field Effect Transistor (FET), using the Replacement Metal Gate (RMG) integration scheme, also known as Gate-Last integration.
FIG. 1 shows starting with a semiconductor substrate which can be formed of any semiconductor such as silicon, germanium, silicon-germanium or other compound semiconductors, the subsequent structures are built. Shown, is the formation of a sacrificial gate, which is formed by conventional deposition or growth of a sacrificial gate dielectric, such as SiO2 or other suitable dielectric, and deposition of a poly-crystalline or amorphous semiconductor, such as silicon or germanium or any compound semiconductor, followed by standard gate lithography and etching to form gate structures. Also shown is a spacer formed by conventional deposition of silicon nitride or other suitable spacer dielectric and standard anisotropic Reactive Ion Etch (RIE) techniques.
FIG. 2 shows the formation of standard source/drain regions formed by ion implantation of dopants, or embedded source/drain formed by etching a trenched, then refilled by epitaxial deposition of doped semiconductor, such as silicon, silicon-germanium, silicon carbon, or other materials, or a combination of ion implantation and epitaxial source/drain formation. As mentioned previously, the source/drain region can be either n-type for NFET or p-type for PFET devices, which can be achieved by utilizing conventional lithography and patterning techniques.
FIG. 3 shows the deposition of an interlayer dielectric (ILD) such as silicon oxide or other suitable dielectric, which is then planarized by conventional Chemical Mechanical Polishing (CMP). The sacrificial gate is removed by a selective wet or plasma etch that removes the sacrificial gate material but not the ILD, nor the spacer material. The sacrificial gate dielectric can also be removed at the step if desired, or it can be retained and incorporated into the final structure. For the purposes of the description, the sacrificial gate dielectric is removed.
FIG. 4 shows the deposition of a gate dielectric stack which can have a single or multiple layers such as an interface oxide or oxynitride layer and high-K dielectric layers such as hafnium oxide, hafnium silicate or other high-K materials. Also shown is the deposition of a workfunction metal material such as TiN on top of the gate dielectric stack. The purpose of the workfunction metal layer is to set the appropriate workfunction to achieve the desired transistor threshold voltage (Vth). The workfunction layer can be a single layer or multiple layers. It should be understood that NFET and PFET transistors may require different workfunction metal layers, which can be achieved by conventional lithography and patterning techniques to place n-type workfunction metal layers in NFET transistor regions and p-type workfunction metal layers in PFET transistor regions.
FIG. 5 shows an additional metal gate deposition on top of the workfunction metal to completely fill the gate region. The metal gate material can be W, Al or other suitable metal which provides a low resistance gate contact or stacks of different metals. The metal gate material can be different between NFET and PFET transistors.
FIG. 6 shows the structure after a conventional metal gate CMP process has been performed to planarize the surface to the top of the gate. The CMP process removes the metal gate, workfunction metal and high-K gate dielectric stacks from the top surface of the wafer, leaving those materials only within the gate. Note also, that because of the CMP process, the top periphery of the high-K dielectric is exposed to the ambient environment during subsequent process steps. In particular, if that ambient environment in subsequent process steps contains any oxygen and the temperature is high enough (>500° C.), the exposed top periphery of the high-K dielectric stack will absorb that oxygen and transport it by diffusion to the gate dielectric to semiconductor channel interface, which causes several problems as will be described in a subsequent section.
FIG. 7 shows the deposition of a middle of line (MOL) dielectric such as silicon nitride or oxide or other suitable dielectric material, which is typically deposited by chemical vapor deposition (CVD) or other conventional techniques at a temperature exceeding 500° C. Because the ambient of the deposition process typically contains some oxygen, the oxygen will be absorbed by the exposed top periphery of the high-K dielectric and transported by diffusion to the gate dielectric to semiconductor channel interface, which causes several problems as will be described in a subsequent section.
FIG. 8 shows in additional detail the structure in FIG. 7, and the issues created by the standard replacement metal gate processing in prior art. As described previously, after the metal gate CMP process to planarize and remove the metal gate, workfunction metal and high-K gate dielectric materials from the top surface of the wafer, the top periphery of the high-K gate dielectric is exposed to ambient of the next process step. The next process step is a conventional MOL dielectric deposition of either silicon nitride or oxide or other suitable dielectric material which is performed at a temperature of 500° C. or more. Because the ambient of these deposition processes typically contains some residual oxygen, the oxygen will be absorbed by the exposed top periphery of the high-K dielectric and transported by diffusion to the gate dielectric to semiconductor channel interface. When oxygen diffuses to the gate dielectric to semiconductor channel interface, several problems can occur. First, the oxygen grows additional unwanted oxide at the critical gate dielectric to semiconductor channel interface, which thickens the effective oxide thickness (EOT) of the gate dielectric stack, which reduces transistor performance. Second, the oxygen shifts transistor Vth away from the desired Vth set point. Third, because the oxygen diffusion and ingress into the gate dielectric to semiconductor channel interface is not well controlled and varies significantly across wafer and from wafer to wafer during processing, both the EOT thickness increase and Vth shifts are highly variable, which severely degrades the overall semiconductor chip performance and manufacturability.
Accordingly, there is a need for a structure and method to minimize the oxygen ingress and diffusion into the gate dielectric to semiconductor channel interface in RMG FET structure and process.

Silicon nitride layer deposited at low temperature to prevent gate dielectric regrowth high-K metal gate field effect transistors


An absorption mat 1 receives organic hydrocarbons in liquid, paste-like or solid form, for example, oil, fats, fuels and solvents. The absorption mat includes a plate-like molded body 2 made of rubber granulate 3 or rubber shavings 3 bonded to each other to define a plate-like body. A base layer 6 resistant to the hydrocarbons is joined by vulcanization to the plate-like molded body 2. The base layer 6 is a composite base barrier layer including first and second layers (10, 12) made of hydrocarbon resistant material and a mesh-like support layer 14 is sandwiched and trapped between the first and second layers (10, 12) for preventing unwanted stretching of the mat during manufacture and when handling before placement on the ground or floor area and when in use.

It is known that liquid, paste-like or solid hydrocarbons have a higher affinity for specific materials than with respect to water. Accordingly, the hydrocarbons can be received or absorbed in bodies manufactured from these materials.
Previously, these characteristics have rather been viewed as a disadvantage because a swelling of the components manufactured from the particular materials resulted.
The invention is, however, directed toward using the known characteristics of these materials in an advantageous manner in order to take up, trap or separate liquid, paste-like or solid hydrocarbons in order to protect the environment.
Any place where such hydrocarbons cannot be prevented from escaping or are emitted because of a work process or treating process, it is of special importance that these hydrocarbons do not directly reach the environment in an unwanted manner and especially that the substances do not reach the ground or are diverted thereto.

Absorption mat and method of making same


A belt turn conveyor includes a conveyor support having first and second generally stationary vertical bearing surfaces and first and second generally stationary horizontal bearing surfaces. An endless belt is rotationally supported by the conveyor support and includes bearing assemblies for engaging the vertical bearing surfaces for retaining the endless belt on the conveyor support. An elongated strip of low friction flexible material is secured to the endless belt for engaging the horizontal surfaces of the conveyor support to restrain vertical movement of the endless belt.

This invention relates generally to a transporting apparatus and, more particularly, to belt turn conveyors, which extend around a curve.
Belt turn conveyors are capable of interconnecting generally straight conveyor sections and provide a turn of up to 180.degree.. Such turn conveyors conventionally includes a pair of conical shaped pulleys, one at each end, and a continuous belt having a smaller length at the inner radius of the turn and a longer length toward the outer radius of the turn. The pulleys and belt are supported by a frame. A conveyor frame typically includes radially spaced legs and horizontal members connecting the legs, which provide a planar support surface for the upper portion of the belt. In operation, especially when the belt is laden with packages or articles to be transported, the belt experiences radial forces, which tend to pull the belt off the pulleys inward of the frame and to cause the belt to ride up against the support frame. Means are provided to retain the belt on the turn conveyor.
In U.S. Pat. No. 4,955,466 to Almes et al., the conveyor belt is provided with an enlarged distal edge (3), which is captured between upper and lower rollers. The rollers are angled so that they bear on an inner, downwardly sloping side of the enlarged edge of the belt and make a line contact with the enlarged edge. Under high speeds of operation, the enlarged edge (3) may tend to distort and flatten so that the belt is not adequately restrained in the vertical direction.
In U.S. Pat. No. 5,332,082 to Sommerfield, a conveyor turn is disclosed which includes a plurality of roller assemblies that are secured to the belt and engage a guide surface provided by a slotted guide rail (31). The vertical movement of the belt is not restrained at its upper portion; instead, the belt is free to lift off the horizontal support member (32) until it makes contact with the free edge of the slotted guide rail. The belt may be subject to increased wear and may experience a shortened operational life.
To overcome the problem of the belt lifting off its support, some conveyors have employed two sets of wheels, one set restrains the belt from sliding off the support and the other set restrains the belt from lifting off the support. For example, in German Document Patent No. DE 41 13 051 C2 discloses two sets of wheel assemblies. However, the supporting structure, which provided the guide rails for the wheels is complicated and generally increases the overall height of the turn conveyor. Furthermore, the spacing between the turn conveyor and the adjacent straight conveyor section is increased in order to accommodate the wheels assemblies and the wheel guide tracks. When the space between the adjacent conveyor sections is increased, smaller packages may fall between the adjacent conveyor sections or may get caught between he sections. Moreover, with the increase in number of wheel assemblies there is a significant increase in noise.
Known belt turn conveyors also tend to have a poor utilization rate because maintenance is difficult and time-consuming when required. This is especially the case with replacement of the belt which has required disassembly of virtually the entire conveyor section. Additionally, difficult alignment procedures have added to the downtime of the conveyor undergoing maintenance or installation.
Therefore, there is a need for a belt turn conveyor which provides means for restraining the belt from lifting off the conveyor support while minimizing the space between adjacent belt conveyor sections and the overall height of the belt turn conveyor and which will reduce the noise of the conveyor when the belt run conveyor is operation. Furthermore, there is a need for a belt that is relatively easy to install and replace.


The present invention provides a fluid controlling apparatus that has a remote signal transmitter that sends a signal to a signal receiver that has power supplied to it by a power supply. The signal receiver now generates a new signal to a valve controller which controls a solenoid operated valve that controls fluid flow from an inlet to an outlet. A first embodiment controls fluid flow which shuts down a power take off commonly driven by an internal combustion engine while a second embodiment controls fluid flow to shut down by movement of an intake air blocker valve, an internal combustion engine. Both embodiments include an indicator including a standby indicating light and an operational indicating light. The valve controller in the first embodiment includes a main solenoid with a fluid flow operated grounding switch for permitting operation of the solenoid operated valve that controls the fluid flow from the inlet to the outlet.

With the advent of the automobile came the requirement for a liquid petroleum fuel. This fuel soon became a requirement for many types of engines used in many forms of machines. Tractors to work the fields and combines to harvest the crop became increasingly popular and to be more competitive people and the environment began to take a beating. The fuel which is now being delivered to the machine operators at or near the workplace brought about a whole new set of circumstances. The drivers of the vehicles delivering the fuel are generally under a lot of pressure especially in spring and fall when time is of the esesnce. These resulting pressure situations make it easy for a bad judgement call to result in an accident. It is to prevent such accidents that applicant has directed the thrust of the instant invention.
Two such attempts known by applicant to avoid the above mentioned accident problem are found in U.S. Pat. No. 5,003,943-Apr. 2, 1991 and Canadian patent No. 599,430-Jun. 7, 1960.
Patent "943" is directed mainly to a device for shutting off the air intake passage of engines. It does, however, disclose a control system to operate the air shut off and fuel shut down thereby stopping the engine. The air is stored in a reservoir and released upon recceipt of a signal. There is a shuttle valve to send an air signal to the governor control for fuel shut down and a shuttle valve to send an air signal to a 4-way valve to operate cylinders which force the baffle plate in the engine intake to cut off operational air supply. Applicants device while performing a similar function is directed mainly to controlling the flow of the pressurized fluid by a remotely initiated electrical signal that controls solenoid operated valve means.
Patent "430" is designed to prevemt excess pressure build up in the pumping system of a delivery vehicle when dispensing fuel oil, gasoline or the like. This excess pressure can cause a great deal of damage to the system. There is a by-pass valve for holding the pressure at an acceptable level. However, under excess rotational speeds the capacity of this by-pass valve can be exceeded with disastrous results. To obviate this problem there is provided a pressure operated engine cut off switch with means to prevent fire in the event of failure of the pressure element. In contrast applicant provides a remote device to control the pressurized fluid that is used to shut down a power take off or to shut off the engine of a vehicle delivering fuel when an emergency situation arises.


A light source module of a white light emitting diode comprising a blue LED, a packaging substrate, wherein the blue LED is mounted on and electrically connected to the packaging substrate, a cap layer, enclosing the blue LED, wherein the cap layer includes a mixture of silicon and phosphor blend at ratio of 1:0.2-0.5, and a protective layer over the cap layer.

Compact white light sources are extensively used for backlight modules of scanners or color panel displays. Therefore, the improvement of white light sources is also great issue for the related industries.
FIG. 1 shows an exploded view of an edge backlight module 10, which comprises a panel light guide 100, a lamp 102 on one side of the panel light guide 100, a lamp reflecting plate 104 on outer side of the lamp 102, and a reflecting plate 106 on bottom of the panel light guide 100. The edge backlight module 10 further comprises prism and light diffusing plates (not shown). The edge backlight module 10 can be used for a panel display and the lamp 102 can be a CCFL for emitting white light. The light emitted from the lamp 102 is reflected by the lamp reflecting plate 104 and then guided by the panel light guide 100, the prism and the light diffusing plate for forward emission. The forward emission can provide backlight for an LCD device.
However, the CCFL has the following problems: (1) complicated circuit design due to a high driving voltage; (2) unstable illumination that varies with the temperature; and (3) a dead zone present at both end of the lamp. When the edge backlight module 10 is used for a scanner, the scanning quality is degraded due to the suboptimal conditions mentioned above.
The rapid progress in LED technologies increases the possibility of replacing the CCFL with an LED, and the white LED can be provided by in the following two ways:
(1) When a blue LED is used with yellow phosphor, the illumination efficiency thereof is influenced by the phosphor.
(2) When red, green and blue LEDs are used together to mix a white light, the color temperature of this white LED may be unstable due to process variation of the LEDS.

This patent is subject to a terminal disclaimer.

High efficiency white light emitting diode and method for manufacturing the same


A balloon dilatation catheter comprises a flexible, tubular catheter shaft which carries a dilatation balloon adjacent the distal end. The catheter shaft defines an inflation lumen communicating with the balloon and a guidewire lumen extending at least most of the length of the catheter and extending through the catheter distal end. A longitudinal slit is defined in the catheter shaft between the guidewire lumen and the catheter exterior. This slit longitudinally extends along the majority of the catheter length from a position proximal of the balloon to a position that is at least adjacent the catheter proximal end.

Dilatation catheters are used in particular for dilating arterial lesions or stenoses in the coronary arteries, when such stenoses threaten to seriously obstruct the flow of blood through the artery. Typically, dilatation catheters are emplaced in the coronary artery stenosis by advancing a guidewire which carries a catheter into the coronary artery, and first advancing the guidewire through the constricted aperture at the stenosis. Then, the dilatation catheter, threaded about the guidewire, is advanced therealong until the balloon of the catheter is positioned within the proper area of the coronary artery, after which the balloon is inflated to dilate the artery wall.
In Bonzel U.S. Pat. No. 4,762,129 a dilatation catheter is disclosed in which the guidewire along which the catheter is advanced is retained in a catheter lumen only at an area near the distal end of the catheter, typically being surrounded by the balloon. Along the rest of the catheter length, the guidewire is free and unconnected to the catheter.
An advantage of this is found in the situation when it becomes necessary to remove the catheter without removing the guidewire. With conventional "over the wire" catheters, it is often necessary in this circumstance to install a guidewire extension on the proximal end of the guidewire prior to withdrawing the catheter, so that the guidewire can at all times be gripped and held in stationary position as the catheter is being withdrawn, to avoid the accidental, partial withdrawal of the guidewire along with the catheter. This is of course undesirable since the distal tip of the guidewire may then be pulled out of the constricted stenosis area of the coronary artery, and thus would require repositioning.
While the guidewire extensions described above are in regular clinical use, they are quite inconvenient since they may have to be four feet long or so, extending and coiling all over the operating room in an inconvenient manner.
With the catheter of the Bonzel patent, the use of a catheter extension may be dispensed with, since the guidewire may be gripped by the surgeon at a position which is lateral to the catheter as the catheter is being withdrawn, since the guidewire is not enclosed in a catheter lumen along most of the length of the catheter. Thus, the catheter can be withdrawn while the guidewire is held in its desired position so that it is not accidentally withdrawn along with the catheter.
Horzewski, et al. U.S. Pat. No. 4,748,982 shows another design of dilatation catheter which can be withdrawn from the patient while leaving the guidewire in a desired position within the patient, without the need for a long guidewire extension. Here also, a large portion of the guidewire is positioned laterally of the catheter rather than within a catheter lumen, so that the catheter may be withdrawn while the guidewire is manually gripped and retained in place. Also, the guidewire can pass through a longitudinal slot 36 defined in the catheter of the Horzewski, et al. patent, as described therein.
Both of the catheters disclosed in the patents cited above exhibit significant clinical disadvantages. For example, conventional, over-the-wire dilatation catheters, where the guidewire occupies a catheter lumen throughout most of its length, are better subject to control of the catheter as it is advanced into the arterial system of the patient. Difficulties are encountered in the tracking of catheters which lack a guidewire passing through the great majority of its length. This complicates and renders more difficult the basic advancement technique of such catheters to their desired point of use within the arterial system of the patient. Generally, dilatation catheters having short guidewire-containing lumens relative to their overall length need to carry some other form of stiffener, such as a metal rod or tube, in order to obtain the minimum standards of trackability and pushability. This adds to the complexity and cost of the catheter structure.
Also, in some clinical situations there may be a need to replace the guidewire rather than the catheter after both have been emplaced. This is very difficult to accomplish with the catheters of the two cited patents.
Accordingly, there is a clinical need for a dilatation catheter which exhibits the advantages of the catheters of the cited patents, but which also exhibits the advantages of conventional, over-the-wire catheters, in that they should be easily controllable due to the presence of the guidewire along most or all of the length thereof, with the desired catheter not requiring a stiff, reinforcing rod or tube as part of the catheter itself. Such a catheter needs to have excellent trackability and pushability, while at the same time it can be replaced without the need of a long, cumbersome catheter extension attached to the distal end of the guidewire.
Also, there is a need for a catheter exhibiting all of these advantages, in which, after emplacement of the catheter, the guidewire can be easily replaced rather than the catheter, if that is desired, but the catheter can also be easily replaced when that is desired.
By this invention, a catheter exhibiting the above advantages is provided. The catheter of this invention is very effective both in clinical utility and flexibility, while remaining of low cost and simple construction.


In a demodulation circuit for demodulating a pulse position modulation (PPM) signal, and a camera having the demodulation circuit, a change in PPM signal is counted by an up/down counter which is switched between count-up and count-down modes every time the PPM signal changes. When a carry signal is output from the counter, the carry signal is latched, and the PPM signal is demodulated into binary data on the basis of the presence/absence of the carry signal in the count-up mode and the carry signal in the count-down mode.

1. Field of the Invention
The present invention relates to a demodulation circuit for demodulating modulated continuous binary signals and a camera with the demodulation circuit.
2. Related Background Art
The invention associated with a technique of this type, U.S. Pat. No. 4,964,139 is known, and has an arrangement shown in FIG. 10 and timing characteristics shown in FIG. 11.
A binary information decoder circuit 100 shown in FIG. 10 comprises a read/write magnetic head 101, a pre-amplifier 102 for amplifying the output signal from the magnetic head, a filter 103 for removing an unnecessary component from the amplified output, a post-amplifier 104 for amplifying the output signal from the filter 103, a detector 105 (including a negative peak detector (NPD) 106 and a positive peak detector (PPD) 107) for detecting necessary signal components from the output signal from the post-amplifier 104, a delay circuit 108 connected to the NPD 106, a flip-flop circuit 109, which is set in response to the output from the delay circuit 108, and is cleared in response to the output from the PPD 107, a clock circuit 110 for generating a clock signal, and an up/down counter 111 for counting up/down the output from the flip-flop circuit 109.
The most significant bit (MSB) of the output from the up/down counter 111 and the output (CLOCK) from the NPD 106 are supplied to a computer 112.
In this circuit, as shown in FIG. 11, a pulse read signal (B) from the magnetic head 101 appears in synchronism with the leading and trailing edges of a modulated data waveform (A), and corresponding threshold peaks (C) of the read signal (B) are detected by the NPD 106 and the PPD 107. The flip-flop circuit 109 is driven by the outputs (D) from the NPD 106 and the PPD 107.
Modulation in this case is made such that when a data signal rises before a time 1/2 the interval of the clock signal (C) (left side of FIG. 11), it indicates "0"; when the data signal rises after the time (right side of FIG. 11), it indicates "1".
However, according to this prior art, since a count-down operation continues even after an overflow signal is output in a count-down mode, the overflow signal (MSB=1) becomes MSB=0, and a signal to be demodulated to "0" is undesirably demodulated to "1".
When the clock interval (C) in FIG. 11 becomes larger than the count value of the counter 111, an overflow signal (MSB=1) is undesirably output even in a count-up mode, and a signal to be demodulated to "1" is undesirably demodulated to "0".

Demodulation processing circuit with time interval counting feature


Since it is difficult to control correctly and optimally the DC biases of an IQ modulator driven with pre-equalized data, a method for controlling an optical transmitter according to an exemplary aspect of the invention includes the steps of (a) making direct current biases for driving children Mach-Zehnder modulators of an IQ modulator in the optical transmitter converge to values close to null driving points of the children Mach-Zehnder modulators, (b) driving the children Mach-Zehnder modulators with special driving data including a pair of training patterns between which there is a significant correlation, (c) scanning direct current biases for setting quadrature angle of the IQ modulator, (d) monitoring output of the IQ modulator during step (c), and (e) setting the direct current bias for setting quadrature angle on the basis of the driving data and monitored results in step (d).

Digital Signal Processing (DSP) techniques enable an optical transmitter to compensate the impairments affecting optical signal during transmission over a fiber by applying the inverse filter properties of the impairments. These techniques can be applied at two different stages of a transmission system including a transmitter and a receiver respectively transmitting and receiving a light wave signal through a medium, such as an optical fiber.
In the first way, the implementation of the DSP technique is performed at the receiver. Notably, a coherent reception technology enables the receiver to get the information on both phase and amplitude of the received signal. This will allow the DSP to compensate for impairments occurring during transmission before the reception by utilizing appropriately calculated filters. An example of signal equalization in this configuration is illustrated in the non patent literature 1 (NPL1). Furthermore, the equalization based on DSP can be implemented in a signal processor as described in the non patent literature 2 (NPL2).
In another way, the implementation of the DSP technique for equalization is performed at the transmitter. The equalization at the transmitter can be either called pre-distortion, pre-equalization, or pre-compensation depending on the sources. This will allow the DSP to compensate for impairments occurring during transmission after emission of the pre-equalized signal by utilizing appropriately calculated filters. The transmitter emits therefore signal that has been distorted in both amplitude and phase information according to the filters, in order to compensate for the signal with the impairment occurring during transmission in the medium. The non patent literature 3 (NPL3) discloses an example of pre-equalization technique, where both linear impairments like chromatic dispersion (CD) and non-linear impairments like Self Phase Modulation (SPM) are compensated in this manner. The pre-equalization with a DSP enables the transmitter to perform equalization in a more economic way than with a dedicated processor. Alternatively, pre-equalization enables to extend the compensating range of the receiver by adding the compensation range of the transmitter.
In NPL3, the pre-equalized signal is modulated on the optical carrier with an optical IQ modulator (In phase—Quadrature phase modulator), sometimes called Cartesian modulator, vector modulator, Dual Parallel modulator, or nested modulator depending on the sources. In an IQ modulator, the electric signals drive two independent Mach-Zehnder devices, which can be called children Mach-Zehnder Modulators (MZM), or nested MZM depending on the sources. The children MZM modulate the phase and amplitude of the same optical carrier wave. The phase in one of their outputs is relatively delayed by 90 degrees before being recombined. The phase delay between the outputs of the children MZM can be called an angle of quadrature and is ideally 90 degrees, modulo 180 degrees. IQ Modulators enable a chirp-free modulation for the amplitude and phase information in the pre-equalized signal by accessing directly to the I component and the Q component of the light wave signal.
However, it is known that there is a drift of DC (Direct Current) bias in IQ modulators due to variation of the temperature or ageing of the device. There are three types of applied biases, that is, the DC biases of each of the two children MZM and DC bias used to set the angle of quadrature. The drift of DC (Direct Current) bias causes a degradation of the transmitted signal, and therefore results in degradation of the received signal quality or in worst cases the impossibility to decode the received signal. This problem is likely to be revealed in the characterization tests of the modulator at the production stage or at the assembly stage of the transmitter in which the modulator is used. This problem can be solved by using Auto Bias. Control (ABC) circuits, which control the biases of the modulators and compensate for the DC bias change. In this manner, ABC technology can manage the drift of DC bias of IQ modulators, enabling correct modulation in optimal condition.
An example of ABC circuits, which is able to control the DC biases of an IQ modulator driven with multilevel signals in order to generate QAM modulated optical signal, is disclosed in the patent literature 1 (PTL1). The ABC circuit of PTL1 is based on low frequency dither tones to control the DC biases of I and Q components in the children MZM as well as of the angle of quadrature. However, due to the properties of the monitor signal, the optimal DC biases of the children MZM have a periodicity of 2*Vpi, where Vpi is the voltage difference between the biases corresponding to constructive interferences and destructive interferences of the MZM. Similarly, the optimal quadrature angle has a periodicity of 180 degrees. Because of these periodicities, there is an uncertainty of 2*Vpi on the set of DC biases in the children MZM and an uncertainty of 180 degrees of the quadrature angle in the IQ modulator.
Another example of ABC circuits, which is capable of controlling the three biases of an IQ modulator driven with pre-equalized data for pre-equalization of CD, is reported in the non patent literature 4 (NPL4). According to the design of ABC circuits including the example in NPL4, the optimal point for the DC biases of the children MZM is the point of minimum transmission at Vpi, where a phase difference of 180 degrees is created by the DC bias between two arms of the children MZM. The optimal bias point is periodic by 2*Vpi. The angle of quadrature is periodic by 180 degrees. According to these periodicities, there is an uncertainty of 2*Vpi on the set of DC biases in the children MZM and an uncertainty of 180 degrees of the quadrature angle in the IQ modulator.
The output complex field representing the lightwave signal modulated by an IQ modulator can be expressed by the following equation:
                                          E            out                                          (                          t              ,                              V                                  bias                  ,                  I                                            ,                              V                                  bias                  ,                  Q                                            ,                              φ                IQ                                      )                          =                                                            E                0                                                          (                t                )                                      2                                                                     [                                                cos                                                        (                                                                  π                        2                                            ×                                                                                V                                                              RF                                ,                                I                                                                                (                              t                              )                                                                                +                                                      V                                                          bias                              ,                              I                                                                                V                          π                                                                                )                                                  +                                                      ⅇ                                          jφ                      IQ                                                        ×                                      cos                                                              (                                                                        π                          2                                                ×                                                                                V                                                                  RF                                  ,                                  Q                                                                                (                                t                                )                                                                                +                                                          V                                                              bias                                ,                                Q                                                                                V                            π                                                                                )                                                                                ]                                                          (        1        )            where Eout(t) represents the output complex field, E0(t) is proportional to the complex field of the input lightwave signal of the IQ modulator, Vbias,I represents the DC bias of the I child MZM in the IQ modulator, Vbias,Q represents the DC bias of the Q child MZM in the IQ modulator, φIQ is the angle of quadrature of the IQ modulator, VRF,I(t) represents a driving voltage of I child MZM in the IQ modulator, VRF,Q(t) represents a driving voltage of Q child MZM in the IQ modulator, and Vπ represents a voltage difference between the biases corresponding to constructive interferences and destructive interferences in the children MZM. In this convention, the case Vbias,I=Vπ represents biasing at the null driving point of the child I Mach-Zehnder modulator.
Considering the case of an IQ modulator, with optimal DC biases, the output complex field is as follows:Eout,optimal(t)=Eout(t,Vπ,Vπ,90)  (2)where the DC biases of the MZM children are set at Vpi and the angle of quadrature of the IQ modulator is set at 90 degrees.
Referring to the ambiguity of the optimal DC biases set by an ABC circuit controlling the IQ modulator, the following cases are also optimal considering the DC biases of the IQ modulator:Eout(t,3×Vπ,Vπ,90)=−Eout,optimal(t) (Opposite of the complex conjugate of (2)),  (3)Eout(t,Vπ,3×Vπ,90)=Eout,optimal(t) (Complex conjugate of (2)),  (4)Eout(t,Vπ,Vπ,270)=Eout,optimal(t) (Complex conjugate of (2)),  (5)
In the case of modulation of signal with QPSK or QAM format with the IQ modulator, depending on the DC bias set by the ABC circuit and considering the uncertainty of the set DC bias, the output field is susceptible to a reference output filed such as its opposite, its complex conjugate, or the opposite of its complex conjugate. The uncertainty of the state can be easily resolved at the receiver after symbol decision using training pattern or framing information.

Optical transmitter and method for controlling the same


A method and apparatus for determining locations for and placing k caches in a network for optimizing performance of a network parameter. The method includes the steps of selecting a placement parameter l that is greater than 0, assigning l caches to l arbitrary nodes in the network. selecting l caches to remove from the network, assigning l+1 caches to every possible location in the network, computing and recording network performance data on the network cost parameter for each location and for each selection of l caches, determining a location where the network performance data on the network cost parameter computed and recorded is optimized, assigning l+1 caches to the determined location, and repeating the above steps of selecting l caches, assigning l+1 caches, computing and recording network performance, determining a location, and assigning l+1 caches for kxe2x88x921 iterations.

The present invention relates to wide-area networks and, more specifically, to a method and appratus for determining an optimal location for caches in a wide-area network.
Internet usage is expanding at a phenomenal rate. As Internet users become more sophisticated, their demands for information and network performance become greater and they become less tolerable of having to wait more than a few seconds for information to be transferred from a server. For world-wide-web (i.e., xe2x80x9cWWWxe2x80x9d) traffic, network performance depends on a number of factors. For example, server response time (i.e., the length of time it takes for a server to respond to a user""s request) slows as the number of users (the terms user and client are used interchangeably herein) accessing the server increases. The type of information (text-only, video, etc.) requested also effects server response time, text-only data consuming less bandwidth and generally being transmitted more quickly than video data, for example. In addition, physical network limitations such as the user""s modem speed, communication route between the user and server (i.e., how many hops the request from the user and information from the server must navigate), the location and number of routers and caches (i.e., network configuration), the speed of the line or link, and other physical factors, may effect server response time.
The case of optimizing performance for clients of a particular web-server is of particular interest both from the theoretical and practical points of view. Consider a popular server that gets many requests and responds with large quantities of data (like big software and news distribution servers). As the number of requests to the server and the data it provides increase, the performance of the server declines sharply. One way to address this problem is to replicate the server. However, explicit replication creates problems with managing the different copies of data maintained on the different servers and redirecting the client to different locations instead of being routed directly to the xe2x80x9coriginalxe2x80x9d server. Consequently, hardware and network management costs increase with this solution.
Another solution is to place more caches in the network. Caching improves network and system performance for world-wide-web (WWW) browsing by saving network bandwidth, reducing client access time, and alleviating server load. The way caches are currently deployed requires clients or caches to be cognizant of proximately located caches. This complicates network and system management and configuration.
Automatic caching is an attractive proposition. The question of where to locate caches in the network is an important one and one which may have a big impact on the overall improvement in network performance. If caches are located very close to the server, the server load may decrease but network congestion will remain a problem. Locating caches too close to the clients would require a large number of caches that would each be under-utilized.
Caches have historically been located at the network edges in the form of browser and proxy caches, at the ends of high latency links, or as part of cache hierarchies. Recently, it has been suggested that caches be placed inside the network, i.e., inside the network backbone, as opposed to at the network edges. Such cache placement has been shown to reduce network FTP (file transfer protocol) traffic. While offering some improvement in network performance, merely locating caches inside the network does not provide an optimal solution to network performance concerns. Moreover, the xe2x80x9cin-networkxe2x80x9d approach, in and of itself, does not provide a method for optimizing network performance or gain (i.e., minimizing overall network traffic and/or reducing server response time or delay). Clearly, how well caching inside the network will work depends on where the caches are located, and how data is disseminated to them.
In view of the above-described shortcomings of the prior art, it is thus desirable to provide a method of determining locations for caches within a network that optimizes a predetermined network cost parameter.
In a first embodiment of the present invention, a so-called l-greedy algorithm is used to determine locations for k caches in a network having virtually any configuration. In a second embodiment of the present invention, a dynamic-programming algorithm determines optimal locations for k caches in a network for the traffic related to a single server. In accordance with the present invention, caches are preferably co-located with network routers and may be maintained by network providers. Thus, little or no change is required to the network infrastructure, except for the introduction of caches at the appropriate locations within the network. The present invention is particularly, although not exclusively, well-suited for a single web-server connected to a network, where the route from the server to the client forms a tree (with the server at the root of the tree).
In a first embodiment, the present invention provides a method of determining locations for k caches in a network. A network configuration is defined by a plurality of network connections, a plurality of nodes, and a plurality of servers and clients and network performance is determined by the interrelation therebetween and there among. The locations determined for k caches optimizes performance of a network cost parameter which is dependent upon the network configuration. The method comprises the steps of: selecting a placement parameter l that is greater than 0; assigning l caches to l arbitrary nodes in the network; selecting l caches from the network; assigning l+1 caches to every possible location in the network; computing and recording network performance data on the network cost parameter for each location and for each selection of l caches; determining a location where the network performance data on the network cost parameter is optimized; assigning l+1 caches to the previously determined location where the cost parameter is optimized; and repeating the previous steps for kxe2x88x92l iterations.
In a second embodiment of the present invention, a dynamic programming algorithm is used to determine the optimal location of a cache in a network having a single server. In this embodiment, the present invention uses a dynamic programming algorithm to compute the optimal cost C(i, {tilde over (k)}, s) to determine an optimal location for caches in a network having a single server, where i is a node, {tilde over (k)} is the number of optimally placed caches, and s is the distance between node i and the next cache in the network.
Other objects and features of the present invention will become apparent from the following detailed description, considered in conjunction with the accompanying drawing figures. It is to be understood, however, that the drawings, which are not to scale, are designed solely for the purpose of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims.

Method and apparatus for locating caches in a network to optimize performance


A lighting array including one or more antimicrobial light segments configured to emit light sufficient to inactivate one or more microorganisms at a target surface may be installed within identified contamination zones of food or beverage preparation, processing, storing or packaging equipment or machinery. In an ice machine, for example, an array controller is configured for communication with an ice machine controller to receive ice machine status information signals. The status information signals are usable by the array controller to determine cycle, state, and/or usage information associated with the ice machine. The array controller may individually control activation of the one or more antimicrobial light segments based on the status information signals received from the machine controller to achieve inactivation of one or more microorganisms on target surfaces within the machine.

During the processing, preparation, storage, and packaging of food and beverage products, the food or beverage product may encounter microorganisms which may make the food or beverage product unsuitable for consumption. The microorganisms may come from the food itself, the food contact surfaces, and/or the surrounding environment. The microorganisms can range from pathogenic microorganisms (e.g., Listeria monocytogenes, enterohemorrhagic Escherichia coli, Salmonella, and the like) to spoilage organisms that can affect the taste, color, and/or smell of the final food product (e.g., Pseudomonas, Acinetobacter, Moraxella, Alcaligenes, Flavobacterium, Envinia, and the like). Microorganisms can affect a wide variety of food and beverage products including meat, poultry, fish and shellfish, cheese, fruits and vegetables, pre-prepared foods, beverages, water, ice, etc. These microorganisms may not only affect the quality of the food or beverage; microbial growth may also be present in and on the associated food processing, preparation, storage, or packaging equipment. At certain levels, the presence of microorganisms on a food or beverage product, or on the associated equipment, may cause everything from a consumer's perception of a lower quality product, regulatory investigations and sanctions, to the spread of foodborne illnesses. Thorough and frequent sanitization of equipment is thus important to help reduce the growth of such microorganisms.

Reducing microbial growth on food preparation, storage, or processing apparatus


Disclosed are gel-based cosmetic and wound-healing formulations, methods for making said formulations, and a method for simultaneously treating and concealing injuries to human skin. In one exemplary embodiment, the cosmetic and wound-healing formulation comprises live yeast cell extract, pigment, and a gel.

1. Field of the Invention
The present invention relates to compositions applied to the skin for cosmetic and healing purposes.
2. Description of the Related Art
Both cosmetic creams and healing creams are well known. Both of these types of topically applied compositions are frequently made with a petroleum base to deliver pigments and healing factors to the skin.
Cosmetic creams typically include a hydrocarbon base in combination with pigments. Occlusive natural oils and synthetic long-chain hydrocarbons have been used in construction of modern makeup or foundation bases. Such oils and hydrocarbons impart sheen, function as binders for the waxy components in the formula, and form the bases of the oil phase of conventional emulsion systems.
Physicians often prescribe to patients wound-healing creams to expedite healing of wounds and the surrounding skin. Live yeast cell extract (LYCE), Aloe Vera, colostrum and Vitamin E are examples of common healing factors, LYCE, which has been variously called Biodynes, Skin Respiratory Factors, and Tissue Respiratory Factors, can be harvested from the nucleus of saccharmoyces cerevisiae cells after the yeast has been cultured in an appropriate nutritional media and then stressed by heat, or by UV radiation (˜286 nm), x-rays or chemical injury. Irradiation and especially elevated temperatures produce heat stress, or heat-shock proteins, in all cells (Demple, B. 1998. Signal transduction: a bridge to control. Science 279(5357) 1655). Elevated temperature causes cellular proteins to lose their three-dimensional structure, and heat stress proteins are capable of restoring the original configuration. If the cell is then removed and its protoplasm concentrated, LYCE may be obtained. LYCE can be prepared as an alcohol extract of viable Saccharomyces Lysate. LYCE stimulates wound oxygen consumption, epitheliazation, and collagen synthesis. In topical medicinal preparations, LYCE is characterized and quantified in terms of Skin Respiratory Factor (SRF) units. A unit of activity is calculated as the amount of SRF which is required to increase the oxygen uptake of 1 mg of dry weight rat abdominal skin by 1 percent at the end of a 1 hour testing period in a Warburg apparatus.
LYCE-biofactors harvested from saccharmoyces cerevisiae contain nutrients such as peptides, proteins, amino acids, minerals carbohydrates, nucleic acid and other gene products. After processing, LYCE-biofactors are clear and sediment-free, retaining the active components without the dark color or odor of the starting material (Fishman, H. M. 2001. Yeast Has Applications In The Cosmetics Industry, HAPPI, July, 42). LYCE biofactors may induce a respiratory response in viable cells, as measured by Warburg Assay, by spectrophotometric absorbance, or by oxygen electrode measurement of cultured human fibroblasts (Lods, L., D. Scholz, C. Dres, C. Johnson & G. Brooks. 2000. Peroxide-Inducible Protective Factors Produced by Saccharomyces cerevisiae. Cosmet & Toil 115(12) 61-6. Fishman, H. M. 2001. Yeast Has Applications In The Cosmetics Industry, HAPPI, July, 42). Further, when delivered to the lower strata of the skin, LYCE biofactors stimulate oxygen consumption by viable cells, causing cellular proliferation and collagen and elastin synthesis.
Temporary cosmetic side effects, such as swelling, bruising, or visible scars, commonly result from plastic surgery or other injuries to skin. It may take days, weeks, or even months before wounds heal and such side effects disappear. Historically, healing creams and cosmetic creams have been used independently to heal and disguise skin wounds.

Gel-based cosmetic and wound-healing formulation and method


A continuous motion device for the therapy and rehabilitation of a patient's hand and fingers comprises a splint adapted to be mounted to the patient's forearm and hand, a gear housing rotatably mounted around a reversible motor, with the reversible motor driving a gear mechanism provided in the gear housing. The gear mechanism driving a digit attachment member in a rotational movement therewith. When actuated, the reversible motor causes the gear housing to rotate about the axis of the motor with the digit attachment member counter-rotating relative to the gear housing about another axis spaced apart from and parallel to the motor axis, whereby the absolute motion of the digit attachment member and therefore of the patient's fingers follow a compound spiral. The compound spiral, depending on the ratios of the gears of the gear mechanism, can follow one of a series of multiple lobed compound spirals, having open or closed loops. The range of motion of the digit attachment member and the speed thereof can be adjusted. Various motions can thus be imparted to the fingers of the patient.

1. Field of the Invention
The present invention relates to continuous passive motion (CPM) devices and, more particularly, to such a device intended for the therapy and rehabilitation of the hand.
2. Description of the Prior Art
Various devices have been contemplated to rehabilitate the hands or the digits thereof through continuous passive motion therapy.
U.S. Pat. No. 1,720,571 issued to Retif on Jul. 9, 1929, discloses an apparatus for exercising the fingers which comprises a flywheel adapted to cause, upon its rotation, a pair of shafts to oscillate. The shafts carry altogether as many collars thereon as there are fingers to exercise. A swivel lever is fixed at a first end thereof by way of a sleeve to each of these collars. The swivel levers are adapted to hold at their second ends the fingers to impart thereto, upon oscillation of the shafts and the collars, various movements in a plane. Various exercises can be obtained depending on the positions of the collars on the shafts.
U.S. Pat. No. 4,368,728, issued to Pasbriq on Jan. 18, 1983, discloses an appliance for training finger joints which includes a plurality of guides mounted in a housing with each of the guides being movable up and down transversely to its longitudinal direction. A plurality of sleeve carriers are slidably mounted on respective ones of the guides. A plurality of finger sleeves extend on top of the housing and are secured to respective ones of the sleeve carriers. A drive is provided for reciprocating the guides up and down with the sleeve carriers and finger sleeves and for reciprocating the sleeve carriers with the finger sleeves along said guides. A horizontal shaft is mounted in the housing for rotation on a first axis. The drive comprises a motor for rotating the shaft. A plurality of eccentric cam wheels are non-rotatably mounted on the shaft. A plurality of levers are pivoted in the housing on a common second axis, which is parallel to the first axis. Each of the levers has a forward end portion, which is spaced from the second axis and constitutes one of the guides and is formed with a longitudinal groove, which receives one of the sleeve carriers. Each the levers rides on the periphery of one of the cam wheels between the groove and the second axis.
"The Journal of Hand Surgery" (pages 474-480, 1979, American Society for Surgery of the Hand) is of interest as disclosing a traction device motor driven through extension flexion for reciprocally and independently driving the digits of a ptient hand along an a curved plastic trolley support. The motor drives a hidden drum, on the periphery which are mounted four rings driven by drive arms mounted directly on the surface of the drum. The rings each have two adjustable tabs that can be moved along the circumference of the ring, the position of these tabs directly relating to the location of trolleys riding on the curved support. Calibration marks assist in locating the tabs in reference to the desired operating range of the trolley which can be each custom set to operate within a determined tolerance range. Similarly, U.S. Pat. No. 4,724,827, issued to Schenck on Feb. 16, 1988, discloses a dynamic traction device for the traction and the flection of an injured area to expedite the healing of bone or soft tissue fractures or other tissues in a patient. For instance, an appendage having a fractured bone is placed in traction and at the same time continuously flexed and extended as is a particular Joint proximally connected to the fractured bone in order to prevent joint tissue deterioration. The portable finger dynamic traction device includes a support structure which is attachable to the body to substantially immobilize joints of the body proximal to the particular joint as is necessary to promote flexing of the proximal joint. Associated with the support structure is an actuator reciprocally movable in a substantially arcuate path which is substantially in the plane of the natural bending movement of the particular joint, distally outward of the fracture and with the particular Joint substantially at the radial center. A tension member tractions the broken appendage to the movable actuator so that the appendage follows the reciprocating movement of the actuator to flex the joint.
U.S. Pat. No. 4,962,756 issued to Shamir et al. on Oct. 16, 1990 and assigned to Danninger Medical Technology, Inc., discloses a portable CPM device which causes controlled continuous passive motion of the digits of a patient's hand. For example, the device when mounted on the dorsal surface of the hand for imparting motion to the four fingers comprises a housing with a motor driven actuating mechanism located therein. The actuating mechanism comprises a reciprocating linear actuation linked to a rotary actuator so that, for therapy of the fingers, the device is rotated about an axis located on the patient's hand that extends transverse to the longitudinal axis of the patient's arm and simultaneously to an actuating arm which is linked to the digits driven back and forth. Linear and rotational elements of actuation are produced, whereby operation of the motor causes the actuating mechanism to drive the digits in a spiral or, more particularly, in a section of a spiral about the axis of rotation, whereby a full palmar closure of the digits in the hand is achieved.
In U.S. Pat. No. 4,679,548 issued on Jul. 14, 1987 to pecheux, the company "Compagnie Generale de Materiel Orthopedique" have also developed a continuous passive motion device which imparts to the fingers a movement resembling that of part of a spiral.
No previous machine provides for the complete motion of all of the joints of the digits, which the present invention achieves through the application of a compound spiral motion to the fingers.


A method of inhibiting transport of nucleic acids between the nucleus and cytoplasm of a cell is disclosed. In one embodiment, this method comprises the step of exposing a cell to a sufficient amount of vesicular stomatitis virus M protein such that the transport of RNA and protein through the nuclear envelope of the cell is impeded. A chimeric RNA capable of nuclear export is also disclosed.

The transport of macromolecules through the nuclear envelope is a complex process that involves many protein factors and an energy source such as GTP (see E. Izaurralde and I.W. Mattaj, Cell 81:153, 1995 and D. Gorlich, et al., Science 271:1513, 1996 for review). Besides the many components of the nuclear pore complex (NPC), several soluble proteins localized to one or both sides of the nuclear envelope are also essential. Key to this process are the nucleotide GTP, a GTPase (Ran) and the nuclear GTP:GDP exchange factor RCC1. We showed previously that RCC1, which is required for export of some messenger RNAs (mRNAs), is also required for export of precursors of small nuclear RNAs (pre-snRNAs) and ribosomal RNAs (rRNAs) but not for that of transfer RNAs (tRNAs). Because pre-snRNAs undergo maturation in the cytoplasm, this inhibition resulted in accumulation of immature RNAs in nuclei.
Keene and coworkers had previously shown that infection of cells by the cytoplasmically replicating negative strand vesicular stomatitis virus (VSV) resulted in inhibition of processing of pre-snRNAs. The similarities between inactivation of the RCC1-dependent export pathway and VSV infection, with respect to accumulation of unprocessed pre-snRNAs, led us to ask if VSV infection might inhibit export of these RNAs from the nuclei of infected cells.
Two VSV gene products have been reported to be present in the nucleus after infection. The two gene products are the newly synthesized 47 nucleotide leader RNA and a pre-existing component of infecting virions, a .about.30 kDa protein called the matrix protein (M protein). Since transcription, but not protein synthesis, is required for inhibition of pre-snRNA maturation, our first attempts were directed at answering the question of whether the leader RNA was responsible for this inhibition. Our inability to reproduce the inhibition by VSV leader RNA led us to question the role of M protein. This protein, present in about 1800 copies per virion, may be released from virions only upon transcription of the leader RNA, at which point it would e free to migrate into the nucleus.

Method of inhibition of nucleo-cytoplasmic transport by M protein of vesicular stomatitis virus


A method of installing a non metallic pipeline segment along with a tracer wire segment using a horizontal directional drilling process includes positioning a horizontal directional drilling machine in a selected position on one side of the obstacle. A drill bit is attached to an end of a flexible steel pipe. The flexible steel pipe engages and is driven by the horizontal directional drilling machine that forces the drill bit and the flexible pipe from the first side of the obstacle to a second side of the obstacle thereby drilling a bore underneath the obstacle. The drill bit is removed and a reamer is attached to the end of the flexible pipe. An end of a pipeline segment along with an end of a tracer wire segment having a high carbon steel core and a copper cladding with a high density polyethylene jacket is attached to the reamer. The drive of the horizontal directional drilling machine is reversed such that the reamer pulls the pipeline and the tracer wire back through the bore beneath the obstacle such that an end of the segment of the pipeline and an end of the segment of the tracer wire extends beyond the first surface of the obstacle.

The present invention relates to horizontal directional drilling. More particularly, the present invention relates to a method of installing a tracer wire segment above a pipeline segment utilizing a horizontal directional drilling process.
Utility companies commonly install non-metallic pipelines to reduce cost. A common non-metallic material of construction for a utility pipeline is polyethylene. Polyethylene pipelines are used by a variety of utilities including, but not limited to, natural gas, water and telecommunications.
Because the pipeline is non-metallic, once the pipeline is buried, it is difficult to precisely determine the pipeline's location. To aid in locating the pipeline, a tracer wire may be installed along with the pipeline such that the location of the pipeline can be detected with a metal detector or a device that detects a signal transmitted along the tracer wire. Typically the tracer wire is positioned between 6 inches and 12 inches above the pipeline to minimize the risk of lightening traveling down the tracer wire and melting or damaging the non-metallic pipeline.
In many instances, the utilities must install the pipeline under an obstacle such as a driveway, a road, a railroad track or a body of water such as a river, a lake or a swamp. Many times, the utility will employ a horizontal directional drilling process that drills a bore beneath the obstruction without causing damage to the above ground landscape where the pipeline segment is installed within the bore.
However, the cost associated with the horizontal directional drilling process are substantially higher than the cost associated with the traditional method of digging a trench and laying the pipe into the trench. While digging a trench may be less expensive than horizontal directional drilling, digging a trench harms the aesthetic appearance of the landscape. In some instances, a trench installation may not be feasible such as when a segment of the pipeline must be installed below a body of water.
The horizontal directional drilling process begins by attaching a drill bit to a length of flexible pipe. The flexible pipe is attached to a horizontal directional-drilling machine which is positioned on one side of the obstruction. The horizontal drilling machine urges the drill bit into the ground to drill a bore beneath the obstruction to another side of the obstruction. At times, the bore can be over a mile in length and having a diameter that is capable of accommodating a pipeline segment having a 12 inch diameter.
When the drill bit bores through to the other side of the obstruction, the drill bit is removed and a reamer is attached to the flexible drilling pipe. An end of a pipeline segment and an end of the tracer wire segment are attached to the reamer. The directional drilling machine pulls the pipeline segment and the tracer wire segment through the bore in the opposite direction of the drill bit. This step in the horizontal directional drilling process is referred to as the "pull back."
As the reamer pulls the pipeline segment and the tracer wire back through the bore, the tracer wire incurs a significant amounts of stresses and strains which has a tendency of causing the tracer wire to break. When the tracer wire breaks, a new bore must be drilled beneath the obstacle and the pull back process must be repeated. Having to repeat the boring and pull back process causes an increase in the time required to complete the project which substantially increases the cost of the project.
A common tracer of wire is a solid copper wire because solid copper is easily detected with a metal detector and has a low resistance which allows a signal to be transmitted down the wire to detect a break. However, a copper wire may not have enough tensile strength to withstand the stresses and strains incurred during the pull back process resulting in the tracer wire segment breaking.
To compensate for the lack of strength of a copper wire, a solid stainless steel wire may be used as the tracer wire. The stainless steel wire has the advantage of being able to withstand a significant amount more stress and strain than a solid copper wire. However, a stainless steel wire is substantially more expensive than a copper wire and has a higher resistance which impedes the transmission of a signal as compared to a copper wire. Therefore, horizontal directional drilling companies are in need of an inexpensive but strong wire that is easily detected but able to transmit a signal along a length of the wire without much resistance.

Method of installing tracer wire with pipeline utilizing horizontal directional drilling


Embodiments herein relate to a method in a user equipment (10) for requesting access to a radio communications network (1), which user equipment (10) comprises at least two transmit antenna ports. The user equipment (10) obtains one or more random access preambles to be used to access the radio communications network. The user equipment (10) transmits; in case of obtaining one random access preamble, the one random access preamble over the at least two transmit antenna ports. In case of obtaining more than one random access preambles, the user equipment (10) transmits each random access preamble over a separate antenna port out of the at least two transmit antenna ports.

In today's radio communications networks a number of different technologies are used, such as Long Term Evolution (LTE), LTE-Advanced, Wideband Code Division Multiple Access (WCDMA), Global System for Mobile communications/Enhanced Data rate for GSM Evolution (GSM/EDGE), Worldwide Interoperability for Microwave Access (WiMax), or Ultra Mobile Broadband (UMB), just to mention a few possible implementations. A radio communications network comprises radio base stations providing radio coverage over at least one respective geographical area forming a cell. The cell definition may also incorporate frequency bands used for transmissions, which means that two different cells may cover the same geographical area but using different frequency bands. User equipments (UE) are served in the cells by the respective radio base station and are communicating with respective radio base station. The user equipments transmit data over an air or radio interface to the radio base stations in uplink (UL) transmissions and the radio base stations transmit data over an air or radio interface to the user equipments in downlink (DL) transmissions.
Currently the Third Generation Partnership Project (3GPP) is evaluating the potential benefits of uplink transmit (Tx) diversity (TxD) in the context of High-Speed Uplink Packet Access (HSUPA). With uplink transmit diversity user equipments that are equipped with two or more transmit antennas are capable of utilizing all of them. FIG. 1 is a schematic overview depicting an example of a user equipment using uplink TxD. The uplink TxD is achieved by multiplying a signal s(t) with a set of complex weights vi. The weights may e.g. define level of amplification, precoding or similar. Note that i=1 . . . N where N denotes the number of transmit antennas, a1-aN. The rationale behind uplink transmit diversity is to adapt the antenna weights so that the user equipment and network performance are maximized in terms of bitrate. Depending on implementation in the user equipment, the antenna weights may be associated with different constraints. Within 3GPP two classes of constraints are considered. Firstly, a class called switched antenna diversity, where the user equipment at any given time-instance transmits from one of the transmit antennas only. Thus if vi≠0, vj=0 for all j≠i. Secondly, a class called beamforming, where the user equipment at a given time-instance can transmit from more than one transmit antenna simultaneously. While switched antenna diversity is possible for UE implementations with a single Power Amplifier (PA) the beamforming implementation may require one PA for each transmit antenna. Switched antenna diversity may be seen as a special case of beamforming where one of the two antenna weights is 1, i.e. switched on, and the other one is 0, i.e. switched off.
Because the radio propagation channels, h1,1-hN,M, from the multiple transmit antennas a1-aN to the receiver antennas, b1-bM, differ, the user equipment and network performance depends on how the multiple antennas are used. A radio network node, e.g. a radio base station, comprises a combiner that combines all the received signals. By using switched antenna diversity or beamforming a gain may be achieved compared to transmission from a single transmit antenna, for example by transmitting from the transmit antenna with the best radio propagation conditions as often as possible. This is the main idea behind these uplink transmit diversity schemes.
In current radio communications networks, e.g. in WCDMA, user equipments in idle state monitor the system information of a radio base station within range to inform itself about candidate radio base stations in the service area etc. When a user equipment needs access to services, the user equipment sends a request over the Random Access Channel (RACH) to a Radio Network Controller (RNC) via the most suitable radio base station, typically the one with the most favorable radio conditions. Since the uplink propagation is only approximately known, the user equipment gradually increases the transmission power of a random access preamble until either the random access preamble has been acknowledged via the downlink Acquisition Indicator Channel (AICH), or the maximum number of attempts of transmitting the random access preamble has been reached. Upon acknowledgement of the random access preamble, the RACH message is sent. After admission control at the RNC, the RNC initiates the connection via the most suitable radio base station if there are available resources.
For each transmission the user equipment selects a random access preamble at random among up to 16 available random access preambles. Each preamble of length 4096 chips is constructed from signature sequences that are scrambled with a scrambling code. The signature sequences are e.g. 256 repetitions of orthogonal 16-chip Hadamard sequences. The random access preamble is typically detected using a matched filter that is matched to the random access preamble signal. The power of the output of the matched filter is typically compared to a detection threshold for random access preamble, and the random access preamble is acknowledged when the output exceeds the detection threshold.
Uplink transmit diversity schemes, such as switched antenna diversity or beamforming, require some knowledge or information about the radio transmission conditions for the multiple transmit antennas. That information may be obtained by explicit feedback from the radio base station, or by measuring how successful previous transmissions have been.
The problem is that the random access preamble, also referred to as the RACH preamble, is the first to be transmitted by a user equipment in WCDMA. That means that the radio communications network and the radio base station is unaware of the user equipment, so no feedback is received, and the user equipment has no immediate previous transmissions to use to select transmit antenna or antenna weights. Also, before a successful random access the radio communications network does not know if the user equipment has uplink transmit diversity capability or not. Therefore it is hard to benefit from the uplink transmit diversity that multiple transmit antennas may give.

Radio network node user equipment and methods therein


An alarm system can remind or alert an adult about the presence of a child in a vehicle. A child detector, such as a weight sensor or weight-activated circuit, can detect whether a child is occupying the child safety seat. The child detector may be integrated with or coupled to a child safety seat. The child detector can be used in coordination with a vehicle alarm system to remind or alert a driver that a child is occupying the child safety seat when a key is not in the ignition.

Embodiments of the present subject matter generally relate to the field of child safety equipment, and, more particularly, to a techniques for integrating a child safety seat with a vehicle alarm system.
Each year, children die from being left unattended in a vehicle. Often a child may be forgotten or left by a driver of the vehicle, such as a caregiver or parent. For example, a driver may neglectfully leave a child in the car while going in for a "quick stop" that takes longer than expected. Alternatively, a driver may simply forget that the child is in the vehicle. For example, the child may fall asleep during a drive and remain quiet for a period of time. Upon arriving at a destination, the driver may be preoccupied or forgetful about the presence of the sleeping child.
Whether the child is left intentionally or unintentionally, being left in a vehicle causes a great risk of injury to the child. The internal weather conditions, such as high temperatures, can cause a fatality in a short period of time. Even when fatality is not the result, a child may be left with serious and possibly permanent injury due to heat exhaustion or dehydration.
It is believed that these tragic accidents can be prevented by a timely reminder to the driver about the presence of a child in the vehicle.


A thermoplastic composite reinforcing sheet material useful for reinforcing orthotic devices and other articles, such as a prosthetic socket or a ski boot. The composite sheet material consists of a plurality of layers. Two layers form outer opposed sides of the sheet and are made from a thermoplastic material. The core of the sheet consists of a plurality of fiber-containing layers. Each layer is impregnated with a thermoplastic resin which will bond with the outer thermoplastic layers when the final shape is vacuum thermoformed. The orientation of the fibers in the core may be varied to change the strength and rigidity of the composite thermoplastic reinforcing sheet. An orthotic device can be built using a thermoplastic host material and the disclosed thermoplastic composite reinforcing sheet material. The host material defines the overall shape of the orthotic device and is any thermoformable thermoplastic. The reinforcing sheet is used to reinforce desired sections of the final orthotic device.

Orthotics are prescribed for a broad range of muscular or joint-related inefficiencies and ailments. An orthotic device may be custom made or made in standard sizes. The customized fit is usually achieved by using a positive mold of the portion of the body over which the orthotic device is intended to be worn. One current practice is to cast the body part with plaster of paris. Once removed from the body, the cast is called a negative model. The cast is dammed off and filled with a slurry mixture of plaster of paris and is allowed to harden. Then, the cast is removed and a plaster edition of the body part is provided called a positive model.
Three general types of materials can be used to shape the orthotic device once a positive mold of the body segment has been provided: thermoplastic resin materials, thermoplastic composite materials, and thermoset composite materials. Each type of material has its own inherent advantages and difficulties.
A primary advantage of thermoplastic resin materials is ease of construction of the orthotic or prosthetic device. These materials can be vacuum thermoformed on the positive mold to thereby provide a customized device. One current fabrication method is to use a monolithic sheet resin, such as polypropylene, heated in a convection oven and drape molded over the positive model. An internal vacuum source assures compliance of the thermoplastic to the positive model. Vacuum thermoforming provides an intimate fit and the transmission of very fine corrective forces from the orthosis to the body segment.
One drawback with thermoplastic resin materials stems from the material is flexibility which makes vacuum thermoforming possible. Thermoplastic resin materials tend to suffer from a lack of ultimate strength and rigidity. To ensure proper rigidity, orthotic devices constructed entirely from thermoplastic resin materials must be quite thick. If too thin, the device may be of limited corrective benefit. For example, when polypropylene is used in a lower extremity device such as an ankle foot orthosis (AFO), the weight of the patient may be sufficient to overcome the rigidity of the orthosis. The corrective benefit inherent in the design of the orthosis would be at least partially lost.
Unlike thermoplastic resin materials, thermoset composite materials can be very rigid and strong. In these materials, layers of fibrous materials impregnated with a thermoset adhesive are used to construct the orthotic or prosthetic device. As disclosed in U.S. Pat. No. 4,439,934, the strength and rigidity of the device can be customized by varying the types of fibers used, and by varying the nap of the fiber layers relative to the stress lines in the orthotic device.
Thermoset composite materials, however, suffer from extremely cumbersome and labor intensive fabrication techniques. Typically, each fiber layer must be individually sized and draped on the positive mold. The final composite is then cured under appropriate conditions.
Thermoset composite materials suffer from two additional difficulties. First, the fiber materials used in constructing the composites can make the final orthotic device very heavy, especially in comparison to devices made solely from thermoplastic resin materials. Second, the fiber materials used to construct the laminated composite are themselves expensive, and greatly increase the cost of the final orthotic device.
As disclosed in U.S. Pat. No. 4,778,717, some thermoplastic composite materials have been used to construct orthotic devices. In a typical construction, a core of thermoplastic material is encapsulated within layers of fiber materials impregnated with the same thermoplastic.
Orthotic devices constructed from these thermoplastic composite materials may avoid some of the problems associated with pure thermoplastics and with thermoset composites. For example, unlike thermoset composites, the thermoplastic composite can be vacuum thermoformed, thus permitting the ease of construction associated with pure thermoplastic materials. The use of external fiber layers increases the strength and rigidity of the orthotic device, thus overcoming the inherent lack of rigidity and strength associated with pure thermoplastics.
Although some of the problems associated with pure or unreinforced thermoplastics and with thermoset composites are overcome by using thermoplastic composite materials to fabricate orthotic devices, these materials nonetheless present some difficulties. The fibers used in the thermoplastic composite make the entire orthotic devices strong and rigid. Thus strength may be provided where it is not particularly needed thereby adding unnecessarily to the weight and material cost of the orthotic device.
Prosthetic devices are manufactured devices for replacing a missing body part, such as a limb or portion thereof. Prosthetic devices that are composed of endoskeletal components typically use a thermoplastic socket for the interface with the residual limb. Endoskeletal prosthetics have components between the socket and the prosthetic foot typically made of metal or plastic materials covered with a non-load bearing soft foam cover shaped to an anatomical profile. The cover is more lifelike than exoskeletal prosthetic devices. Thermoplastic sockets are susceptible to the same disadvantages as orthotic devices when the sockets are made of thermoplastic sheet material in a thermo vacuum-forming process or of other materials as previously described.
An improved material and method is needed to overcome the problems associated with the materials currently used in fabricating orthotic and prosthetic devices. Specifically, it would be advantageous to provide a material and method which can provide an orthotic device that has sufficient strength and rigidity in needed areas without unnecessarily adding to the weight and material cost of the orthotic device.

Thermoplastic composite reinforcement and method for orthotic, prosthetic and other devices


The present invention relates to a composition for coating an organic electrode and method of manufacturing an organic electrode having a excellent transparency using the composition comprising 3% to 20% by weight of a polyhydric alcohol, polyol or a mixture thereof, 5% to 10% by weight of a primary alcohol having C1 to C5, 5% to 25% by weight of a amide, sulfoxide or a mixed solvent thereof, 0.01% to 0.1% by weight of a surfactant and a aqueous solution of polyethylenedioxythiophene (PEDOT) conductive polymers having nano-sized particle in a remainder. The present invention indicates the excellent transparency that transmittance of organic conductive layer is more than 90% in the visible ray area and sheet resistance is 300 to 900 Ω/sq in case of coating. Therefore the present invention is capable of manufacturing the organic electrode such a electrode or a writing material of organic transistor, smart card, antenna, electrode of battery and fuel battery, capacitor using for PCB, inductor, electromagnetic wave cover and a sensor etc. as well as the transparency electrode using for display.

Presently, a study has been progressed about study about a chemical vapor deposition using a various metallic oxide of Indium, Tin, Zinc, Titanium and Cesium, magneton sputtering and a reactive evaporation as a method for preparing transparent electrode at home and abroad. But the study has a demerit resulting in high process cost in order to coat to a metal oxide on the substrate because coating metallic oxide to substrate needs to vacuum condition.
As a method for preparing transparent electrode processed at lower cost, a method for using conductive polymers has been become influential. The electrode processed by using conductive polymers is good for decreasing the process cost and working process because it is capable of using a various existing method for a coating polymer.
In case of manufacturing a flexible display or a electrical light device, when the transparent electrode processed with the conductive polymers such a polyacethylene, polypyrrole, polyaniline and polythiophene is compared with the transparent electrode processed with a Indium Tin Oxide (ITO), it takes advantage of the process, and in case of need for a very flexible electrode, particularly manufacture of touch screen, the transparent electrode processed with the conductive polymers is good for increasing a life time. The transparent electrode have many merits, but generally conductive polymers increases a sheet resistance in case of slightly coating layer in order to increase the transmittance so that conductive polymers absorb a ray in the visible rays area and the conductive feature of organic electrode manufactured by the conductive polymers is increased in proportional to the thickness of the electrode. Therefore the conductive polymers is difficulty in applying to a applicable field of the transparent electrode such a touch panel, flexible display. Particularly in order to improve the process of the conductive polymers, when the transparent electrode is manufactured with the method, wherein the conductive polymers is pulverized to the nano-sized particle and uses commercially available dispersed polythiophene, it shows about 1□/sq of sheet resistance. Therefore it is difficulty in using with the transparent electrode using for displaying in the condition of 85% of transmittance.
U.S. Pat. No. 5,766,515, U.S. Pat. No. 6,083,635 and Korean Patent Publication NO. 2000-1824 disclose a method for improving the conductivity of electrode manufactured with the aqueous solution of polyethylenedioxythiophene (PEDOT) conductive polymers having nano-sized particle by using a solvent or a additive. But U.S. Pat. No. 5,766,515 or U.S. Pat. No. 6,083,635 has a problem as following, when a polyhydric alcohol, e.g sorbitol is added, the sheet resistance of coating layer having more than 90% transmittance is difficult to decrease less than 1 □/sq, and when a amide solvent is added, the sheet resistance of coating layer can be decrease less than 1 □/sq, but a hardness of layer is low and coating feature is diminished. On the other hand, according to Korean Patent Publication NO. 2000-1824, when a silicasol is added to aqueous solution of polythiopene treated with the amide solvent, the hardness of layer is improved, and the sheet resistance is increased more than 1 □/sq in case of improving the hardness of layer.
To consider above the feature, the coating layer shows more than 90% of the transmittance and less than several hundred Ω/sq of the sheet resistance, also has the excellent transparency and hardness and the low resistance. Therefore a development of organic transparency electrode material which can apply to a electronic equipment has been needed continually.

Composition for coating organic electrode and method of manufacturing an organic conductive layer having excellent transparency using the composition


MBE nitrogen sources of dimethylhydrazine, tertiarybutlyhydrazine, nitrogentrifloride, and NHx radicals. Those nitrogen sources are beneficial in forming nitrogen-containing materials on crystalline subtrates using MBE. Semiconductor lasers in general, and VCSEL in particular, that have nitrogen-containing layers can be formed using such nitrogen sources.

1. Field of the Invention
The present invention generally relates to the field of molecular beam epitaxy (MBE). More specifically, the present invention relates to MBE nitrogen sources.
2. Discussion of the Related Art
Molecular beam epitaxy (MBE) is a well-established method of forming thin film depositions on crystalline substrates. The MBE process is performed by heating a crystalline substrate in a vacuum so as to energize the substrate's lattice structure. Then, an atomic or molecular mass beam(s) is directed onto the substrate's surface. When the directed atoms or molecules arrive at the substrate's surface the directed atoms or molecules encounter the substrate's energized lattice structure. The energetic lattice structure then accepts oncoming atoms, possibly after those atoms are separated and removed from molecule. Over time, the oncoming atoms form a film that is characterized by high crystallinity and excellent surface uniformity. Because of its utility and the high quality films produced, MBE is widely used in semiconductor research and in fabricating semiconductor devices, particularly semiconductor devices that benefit from thin-film depositions of elemental materials.
FIG. 1 illustrates an MBE apparatus in operation. As shown, the MBE apparatus includes a chamber 106. During operation, that chamber 106 is ultra highly evacuated. An effusion cell 100 then injects a beam 104 of gaseous atoms or molecules 102 into the chamber 106. The beam 104 is directed at a predetermined angle toward a heated crystalline substrate 110 that is mounted in the chamber 106.
Effusion cells 100 come in a variety of configurations that are beneficially tailored for the specific material(s) being deposited. Effusion cells 100 include a crucible 111 that contains an effusion material 112, for example aluminum, gallium, indium, or other compounds. The crucible 111 and its contents are then heated to effuse the material from an orifice 114 into the chamber 106 and onto the substrate 110. The intensity of the beam 104 is controlled by the temperature of the crucible 111, which is set by a heater 115 (not shown in FIG. 1, but see FIG. 3), and by a shutter 108 positioned in the chamber 106 near the orifice 114. The ultra-high vacuum environment (UHV) used in MBE is typically about 1×10−3 Pa. This enables a relatively low substrate temperature, typically about 750° C.
High purity gases, such as hydrogen, and high vapor pressure materials, such as arsenic, phosphorous, selenium, and sulfur, may be effused by thermally cracking them into dimers or into various atomic species. With gaseous materials, a valve can be used instead of the shutter 108 to control the intensity of the beam 104.
While FIG. 1 illustrates an MBE apparatus in operation, in practice a plurality of effusion cells 100 are used. In such cases, beams 104 from the individual effusion cells can be actuated individually or in conjunction with other beams to produce desired thin films on the substrate 110. In any event the species from the effusion cells travel across the MBE chamber 106 to the substrate 110. There, epitaxial growth occurs according to the controlling deposition kinetics.
MBE has proven useful for producing a wide range of epitaxial films. Of particular interest to the present invention are thin films that contain nitrogen. For example, FIG. 2 illustrates a vertical cavity surface emitting laser (VCSEL) having a nitrogen-containing layer that is suitable for MBE fabrication. As shown, an n-doped gallium arsenide (GaAs) or InP substrate 12 has an n-type electrical contact 14. An n-doped lower mirror stack 16 (a DBR) is on the substrate 12, and an n-type graded-index lower spacer 18 is disposed over the lower mirror stack 16. An active region 20 having a number of nitrogen containing quantum wells, for example GaInAsNSb, is formed over the lower spacer 18. A p-type graded-index top spacer 22 is disposed over the active region 20, and a p-type top mirror stack 24 (another DBR) is disposed over the top spacer 22. Over the top mirror stack 24 is a p-type conduction layer 9, a p-type cap layer 8, and a p-type electrical contact 26.
Still referring to FIG. 2, the lower spacer 18 and the top spacer 22 separate the lower mirror stack 16 from the top mirror stack 24 such that an optical cavity is formed. As the optical cavity is resonant at specific wavelengths, the mirror separation is controlled to resonate at a predetermined wavelength (or at a multiple thereof). At least part of the top mirror stack 24 includes an insulating region 40 that provides for current confinement. The insulating region 40 is usually formed either by implanting protons into the top mirror stack 24, or by forming an oxide layer. The insulating region 40 defines a conductive annular central opening 42 that forms an electrically conductive path through the insulating region 40.
In operation, an external bias cause an electrical current 21 to flow from the p-type electrical contact 26 toward the n-type electrical contact 14. The insulating region 40 and the conductive central opening 42 confine the current 21 such that it flows through the conductive central opening 42 to the active region 20. Some of the electrons in the current 21 are converted into photons in the active region 20. Those photons bounce back and forth (resonate) between the lower mirror stack 16 and the top mirror stack 24. While the lower mirror stack 16 and the top mirror stack 24 are very good reflectors, some of the photons leak out as light 23 that travels along an optical path. Still referring to FIG. 2, the light 23 passes through the p-type conduction layer 9, through the p-type cap layer 8, through an aperture 30 in the p-type electrical contact 26, and out of the surface of the VCSEL 10.
While MBE has proven useful for producing nitrogen-containing layers, such as found in the VCSEL 10, the available nitrogen sources are less than optimal. In practice, two types of nitrogen sources are available: elemental nitrogen and ammonia. Elemental nitrogen is derived from nitrogen plasma, while ammonia is thermally cracked on a heated crystalline substrate (On-Surface Cracking) to produce elemental nitrogen. Because of limitations of available nitrogen sources, new MBE nitrogen sources would be beneficial.

Nitrogen sources for molecular beam epitaxy