The present application is applicable to receivers for Global Positions (GP) systems which use delay-lock loops (DLLs) and, optionally, phase-lock loops (PLLs). The application discloses multipath error reduction techniques which enable the multipath errors in DLL systems to be made much less than the error present in known narrow xe2x80x9cearly-latexe2x80x9d correlators, or their corresponding implementations which use strobe representations of the PR-code. Also disclosed are multipath error reduction techniques that enable multipath errors in the PLL systems to be reduced. The techniques, when applied to both the DLL and PLL systems work synergistically to further reduce multipath errors.

The present invention relates to receivers employed for range measurements using radio-signals encoded by a pseudo-random code, and more particularly to such receivers which reduce the reception errors caused by reflected versions of the directly received signal (i.e., multipath error reduction).
Multichannel receivers for receiving broadcasted radio-signals encoded by repeating pseudo-random (PR) codes are employed by consumers using the global satellite navigation systems GPS (xe2x80x9cNAVSTARxe2x80x9d) and GLN (xe2x80x9cGLONASSxe2x80x9d). These systems enable one to determine the receiver""s location and its velocity vector, and also to determine the time of day. The present invention is applicable to these types of receivers, and to other types of receivers and demodulators which receive signals which are encoded by repeating PR-codes. The signals to be demodulated may be broadcast by antenna, may be transmitted through wire or optical fiber, or may otherwise be transmitted by known transmission means.
In the GPS and GLN systems, the receiver simultaneously receives several broadcasted signals from several corresponding satellites which are xe2x80x9cvisiblexe2x80x9d to the receiver (as used herein, the term xe2x80x9cvisiblexe2x80x9d means that the satellite broadcast signal is not blocked from the receiver by a physical object, such as a building or the Earth). At any one time, 5 to 11 of the 24 GPS satellites are visible to the receiver. Every GPS satellite broadcasts signals in two frequency bands: the L1 band and the L2 band. In the L1 band, two radio-signal carriers are simultaneously broadcasted, each carrier having the same frequency but being phase shifted in time with respect to one another by xcfx80/2 (90xc2x0), which is one-quarter (xc2xc) of the carrier wavelength. One of these carriers is modulated by a clear acquisition code (C/A-code) and the other carrier is modulated by a precision code (P-code). Both of these codes are pseudo-random sequences of +1 and xe2x88x921 values, each sequence having a predetermined length and being continuously repeated. In the L2 band, a single radio-signal carrier is modulated by the above-described P-code, but the frequency of the L2-carrier is substantially lower than that of the L1-carrier. This frequency difference enables one to account for the changing transmission characteristics of the ionosphere. The present invention is applicable to the reception of either or both of the C/A-code and the P-code (in either band). The reception of the C/A-code will be used herein to illustrate the present invention.
In the GPS system, each satellite is assigned its own unique C/A-code, which enables the receiver to distinguish between the satellites even though all the C/A-codes are being modulated onto carriers having substantially the same frequency. Each repeating sequence of a C/A-code is quantized into 1,023 segments, or xe2x80x9cchipsxe2x80x9d, where each chip is of a predetermined time period (xcex94) and has pre-selected value, which is either +1 or xe2x88x921. The sequence repeats itself every millisecond. When the C/A code is modulated onto the carrier, it is often called the C/A-signal. The particular set of chip values for each sequence is unique to the satellite, and the cross-correlation of each C/A-code sequence with those of the other satellites is substantially zero in comparison with the cross-correlation of the signal with itself (auto-correlation). This last feature applies as well to the corresponding C/A-signals and it enables a GPS receiver to isolate any one of the C/A-signals from the others being received by correlating the input signal (after appropriate down-conversion) with the C/A-signal to be isolated.
In order to provide useful timing and positional information, the C/A-signals in some of the satellite-broadcast bands are modulated by a low-frequency (50 Hz), binary-coded information signal A(t) which is transmitted as a repeating sequence of 1,500 bits. Each bit of A(t) has a value of xe2x88x921 or +1, is synchronized to start with the beginning of a C/A-code sequence in the C/A-signal, and spans 20 sequences of the C/A-code. The C/A-signal is so modulated by multiplying its C/A-code sequence values by either xe2x88x921 or +1, depending upon the current bit value of the information signal A(t). In the receiver, the information signal A(t) can be demodulated by correlating the broadcasted C/A-signal with an internally generated version of the C/A-code to provide a correlation signal I(t), and by noting the sign changes in the correlation signal I(t) (assuming that both C/A-signals are substantially synchronized). As a fine technical point, we note that correlation signals in the GPS art, such as I(t), are usually not continuous functions of time since they are often generated by accumulating multiplication products over fixed time durations (TA), with these time durations following one another consecutively. As a result, typical correlation functions are discrete time signals (with update frequency of fA=1/TA). To denote such a discrete time signal, we will use the time indicator symbol xe2x80x9ctKxe2x80x9d as the signal""s time argument, where the subscript xe2x80x9cKxe2x80x9d indicate the discrete nature of the time, such as in the form: I(tK).
For the general benefit of the reader, the following differences between the GPS and GLN systems are noted:
1) In the GPS system, the signals from all the GPS satellites are transmitted on the same carrier frequency (1575.42 MHz in the L1 band, 1227.60 MHz in the L2 band), but each has its own unique PR-code. In the GLN system, the signals from different satellites have different carrier frequencies, but have the same C/A-codes and P-codes.
2) In the GPS system, the xe2x80x9cchipsxe2x80x9d in the C/A-codes are clocked out at a rate of 1.023 MHz (for a chip period xcex94=977.52 ns), whereas the chips for the C/A-code in the GLN system are clocked out at one-half that rate, which is 0.511 MHz (for a chip period xcex94=1956.95 ns).
3) In both systems, the chips for the P-codes are clocked out at a rate which is ten-times that for the clocking rate of their C/A-codes. Specifically, the P-code clocking rate is 10.23 MHz (xcex94=97.75 ns) in the GPS system and 5.110 MHz (xcex94=195.69 ns) in the GLN system.
4) In the GPS system, the P-code is additionally modulated by W-code whose sequence structure is unknown to civilian users. The GLN system has no similar modulation.
In conventional receivers, the broadcast signal from the satellites are received, and down-converted by an appropriate means to provide the desired C/A-codes (or P-codes), usually in a digital form. The down-converted signal bearing all of the received C/A-codes is then provided to one or more individual tracking channels, each of which is intended to isolate one of the satellite C/A-codes from the others and track it. The C/A-code to be tracked by a specific tracking channel is not only obscured by the C/A-codes of other satellites, but by noise signals received by the receiver and noise generated within the electronics of the receiver. In order to isolate the desired C/A-code for the others and from the noise, the down-converted signal is correlated against a replica of the desired C/A-code as indicated above. The reference replica is phase-shifted in time to a point where the correlation of the two signals is at a maximum. The correlation may be performed by multiplying the values of the two signals together at periodic intervals, and then accumulating multiplication products to form the correlation signal I(tK). Devices which perform this operation are called correlators, and may be implemented by hardware, software (i.e., DSP processor) or a combination of both. In typical implementations, the correlator accumulates the multiplication products for a fixed period of time, which is sometimes referred to as the accumulation period or accumulation window. After each accumulation period, the correlator is reset to a value of zero. Typical accumulation periods for GPS/GLN applications are 1-ms, 5-ms, and 10-ms.
Within a period of one C/A-code sequence (e.g., 1,023 chips), the accumulation of the multiplication products of the tracking channel""s replica reference code with the C/A codes of satellites not being tracked by the channel will sum to substantially zero. However, the accumulation of the multiplication products of the reference code and the C/A-code to be tracked by the channel will rise to a non-zero peak value (+MAC or xe2x88x92MAC) when the two signals are synchronized. This value will be provided in the correlation signal I(tK). Whether the output value from the correlator is +MAC or xe2x88x92MAC depends upon the current bit value of the low-frequency information signal A(t), if present, and any polarity difference between the satellite C/A-code and the channel""s reference C/A-code. These dependencies are well known to the GPS/GLN art. (If (A(t) is present, I(tK) will alternate between +MAC and xe2x88x92MAC as a function of A(t)""s value.) As these signals lose synchronization, the accumulation of the multiplication products, which is the correlator output, will move from +MAC or xe2x88x92MAC toward a value of zero, and will settle to a value of zero if the two are out of synchronization by more than one chip period (xcex94).
The correlator whose output demodulates the information signal A(t) is often called the Main Correlator. The correlation of a received PR-code signal with an idealized-version of the same PR-code signal, as generated locally by the receiver with the same sign orientation but out of sync by a time delay xe2x80x9cxcex5xe2x80x9d, is is defined herein as the inter-correlation function: R0(xcex5). R0(xcex5) is more simply referred to as the correlation function R0(xcex5). When xcex5=0, which means the two versions are in sync, R0(xcex5=0) is at its peak magnitude value (+MR0). When e is greater than +1 chip duration (+xcex94) or less then xe2x88x921 chip duration (xe2x88x92xcex94), R0(xcex5) is substantially zero. As xcex5 moves from 0 to +1 chip of delay, R0(xcex5) decreases substantially monotonically with xcex5 from its peak value (+MR0) to zero. Likewise, as xcex5 moves from 0 to xe2x88x921 chip of delay, R0(xcex5) decreases substantially monotonically with s from its peak value (+MR0) to zero. The output of the Main Correlator will be proportional to R0(xcex5), as well as A(t) if A(t) is present. The output I(tK) of the Main Correlator is often used to provide a measure of the satellite""s signal strength.
It should be pointed out that a reference code for a tracking channel need not be a scaled replica of the broadcast C/A-code being tracked. Oftentimes, pulsed versions of the replica are used, as well as strobed versions which each strobe has a grouping of pulses for each chip of the broadcast C/A code. Each of the pulses and strobes is less than the chip duration xcex94. Each pulsed version and each strobed version may have pulses or strobes omitted for selected chips of the code (usually when the chip value does not change from the value of the previous chip). The correlation function of a pulsed version or a strobed version of the C/A code with the received C/A code will be different from the correlation function described above. The conventional notation for representing the correlation function of a pulsed or strobed version with the input code is xe2x80x9cxcex94Rxe2x80x9d rather than xe2x80x9cRxe2x80x9d. In this case, the xe2x80x9cxcex94xe2x80x9d symbol does not represent the chip duration xcex94, and xe2x80x9cxcex94Rxe2x80x9d should not be read as multiplying the correlation function xe2x80x9cRxe2x80x9d by the chip duration (xcex94).
In the case where the broadcast signal comes from a GPS or GLONASS satellite, the information signal A(t) carries a reading of the current time of a master clock, the time information being accurate to within several milliseconds, assuming that one computes the rough transmission delay from the satellite. Additionally, the start of each C/A-code sequence is precisely timed with respect to the master clock, so precisely synchronizing the replica signal with the C/A-code of the broadcast signal could bring the timing accuracy to within less than a one chip duration xcex94 (about one microsecond), assuming that one knows the transmission delay from the satellite. The transmission delay may be determined by comparing information from the L2 band from the same satellite and information from the broadcast signals from other satellites, as is known in the GPS/GLN art. The timing information from four or more satellites can then be used to determine the global position of the receiver on the Earth, and many receivers have four or more Main Correlators for this purpose.
In order to accomplish proper extraction of the timing information and the demodulation of the information signal A(t), if present, the a receiver""s tracking channel has a means of keeping the replica signal in synchronization with the C/A-code of broadcast signal. This means is usually called a delayed-lock loop (DLL) system. The DLL system may use the Main Correlator for maintaining synchronization, but more typically it has one or more of its own correlators for this purpose, each of these correlators using a pulsed or strobed version of the C/A-code, or a replica of the C/A code which are offset in time from that used by the Main Correlator. Also, the tracking channel usually has a means of generating a local carrier for the down-converter whose frequency is continuously adjusted to be in close synchronization with the carrier frequency from the satellite (the C/A-code modulates this carrier frequency). This means is usually called a phase-lock loop (PLL) system, and the tracking channel is said to use the xe2x80x9ccoherent demodulationxe2x80x9d method, and the receiver is often called a xe2x80x9ccoherent receiver.xe2x80x9d Like the DLL system, the PLL system usually has one or more of its own correlators to aid it in isolating the carrier phase of the satellite signal being tracked by the tracking channel. Thus, a typical coherent receiver tracking channel has a Main xe2x88x9215 Correlator, a DLL system, and a PLL system, each of which processes the input signal in individual signal-processing correlators, for a total of three such correlators. For this reason, a coherent tracking channel is sometimes called a three-correlator channel (or sometimes a three-path channel).
In the typical coherent tracking channel, the proper operation of the Main Correlator, the DLL system, and the PLL system are each dependent on the proper operation of the other. For example, each of the DLL and PLL systems uses the demodulated information from the Main Correlator to remove the modulation effects of the low-frequency information signal A(t). In turn, all of the three components use the replica signal, as synchronized by the DLL system, to isolate the desired C/A-code from all of the other C/A-codes and the various source of noise. In turn, the DLL system relies on the PLL system to adjust the carrier phase to provide a maximum signal to noise ratio and to prevent carrier cycle-slips. The operation of each of three components can be disturbed by the presence of multipath signals (i.e., reflected and delayed versions of the broadcast signal).
The PLL system may be replaced with the well-known incoherent demodulator system. In this system, the input signal is down-converted using an independent carrier reference signal which does not have its phase adjusted to follow that of the input signal. Also in this system, the correlation signals for the DLL system and Main Correlator are generated such that they do not depend upon phase synchronization of the independent reference carrier and the input signal. However, this system requires the formation of four signal-processing correlators rather than three, and loses the timing information that may be extracted from the PLL synchronizing the reference carrier with the input carrier (which is a coherent method). The latter information may be extracted by other means, but such means requires additional components. Nonetheless, as the present invention pertains to both DLL and PLL systems, the performance of DLL systems of incoherent tracking channels can benefit from the present invention.
As is well known in the art, an initial-locking control system, or xe2x80x9csearchxe2x80x9d system, is used to bring the DLL and PLL systems into rough alignment with the C/A-code and the carrier of the broadcast signal before these systems begin full tracking operation based upon the interdependence of their output signals. The initial lock control system generally varies the frequency of the local carrier and the phase of the replica code in a predetermined search pattern until a substantial correlation is detected, and thereafter enables full tracking operation. The initial-locking control systems are well known in the art, and are not part of the present invention. Many of the well known initial-locking systems may be used with the present invention. Accordingly, a description of such a system herein is not needed for one of ordinary skill in the art to make, use, and practice the present invention. For the benefit of the reader who is untrained in the field of code searching and tracking, the book entitled xe2x80x9cDigital Communications and Spread Spectrum Systems,xe2x80x9d by Ziemer and Petersen, Macmillian Publishing Company, New York (1985) (ISBN 0-02-431670-9) (Chapters 10 and 11) is a good tutorial reference on these subjects, and the book entitled xe2x80x9cGuide to GPS Positioning,xe2x80x9d by Wells, et al., Canadian GPS Associates, Fredericton, N. B. Canada (1986) (ISBN 0-920-114-73-3) is a good tutorial on GPS systems. The latter reference may be purchased from the Canadian Institute of Surveying and Mapping, Box 5378, Postal Station F, Ottawa, Ontario, Canada, K2C 3J1, telephone (613) 224-9851.
Under real operating conditions, the PLL and DLL systems operate with errors caused by outside disturbances. Exemplary disturbances are additive interferences (including the receiver""s own noise sources), multiplicative interferences (e.g., fluctuations occurring when the radio-waves undergo expansion, generator frequency instability), dynamic disturbances because of the receiver""s physical movement, and so on. In critical cases, these disturbances can lead to the tracking breakdown or to single-cycle slips in the PLL.
One of the most substantial causes of errors is the reflection of the broadcast signal from the ground or nearby physical objects, such as buildings, large boulders, and hills. These errors are often referred to as multipath errors, and can substantially reduce the precision of both the code measurements and the carrier phase measurements.
A number of general methods for dealing with multipath errors are known. One general set of methods derives corrections which are to be applied to the received GPS signals in order to subtract out the effects of the multipath signals. These methods construct a model of the environment surrounding the receiver and compute the magnitudes and phases of the reflected signals. These methods are usually not preferred since a new model for each new environment is required, and is therefore not generally applicable to all situations in which the receiver may be placed.
Another method for dealing with multipath errors is the so called MET technique. In this method, the curve of the correlation function R0(xcex5) is traced out as a function of the delay parameter E to find the peak value of R0(xcex5) and the slope of the curve on each side of the peak. From the peak value and the slopes, an estimation of the reflected signal can be made, and a correction for the multipath signal can be made. Several correlators are typically used in this method, which has the disadvantage of increasing the cost and complexity of the receiver.
Another general set of methods includes special circuitry or signal processing of the received signal which act to reject, or discriminate against, multipath signals. In a conventional receiver which does not have multipath rejection, the received broadcast signal is simultaneously correlated against two versions of the C/A-code by two separate correlators. The second version of the C/A-code is delayed in time from the first version by one-chip duration (xcex94), and the resulting correlations of these versions with the broadcast signal are subtracted from one another to provide the control signal to the DLL. When these two versions are synchronized to the broadcast signal, the control signal has a value of zero, and the chip edges (fronts) of the broadcast signal occur midway between the corresponding chip edges of the two versions (which are often called the xe2x80x9cearlyxe2x80x9d and xe2x80x9clatexe2x80x9d versions). In these receivers, multipath signals which are delayed by less than 1.5 chip durations (1.5xcex94) from the directly received broadcast signal will be correlated into one or both correlations, and will thereby disturb the computation of the control signal. The receivers which include multipath rejection use strobed representations of the early and late C/A-code versions, and use a shorter phase delay between the strobed representations. The strobed representations are normally at a zero value except for small time windows around the start of all of the chip edges (or at selected ones of the chips edges), where the representation has one or more pulses. If there is more than one pulse in such a time window, the pulses are arranged to have a total area of zero (in other words, equal positive and negative areas), and are usually symmetric about a line (or plane) or rotation point. (These features lead to a symmetric discriminator curve.) The basic idea behind these strobe receivers is to only perform the correlations in small sample windows near the points where the directly received signal changes its value so that the value or changes in values of the reflected signals are not sampled or correlated.
Although the strobed receivers provide a great reduction in errors caused by multipath signals, they do have some disadvantages. As one disadvantage, the output signal of the DLL discriminator is zero not only at the point of desired synchronization with the directly-received broadcast signal, but the control signal is zero over much of its range from +1 chip duration (+xcex94) from synchronization to xe2x88x921 chip duration (xe2x88x92xcex94) from synchronization. Thus, an external means, such as a conventional early-late receiver, must be used to bring the receiver close enough to the point of synchronization where the strobe-receiver can function. This has the disadvantage of requiring additional circuitry and/or additional signal processing power. As a corollary to this, the locking range of the strobed receivers is much smaller than that of the conventional early-late correlation receiver. As a second disadvantage, each multipath signal of substantial value will create perturbations in the zero regions of the DLL control signal, and these perturbations have a zero-crossing point which the DLL can falsely lock onto. Therefore, the strobe correlators require means for distinguishing the true point of synchronization from these false-locking points.
While the strobed methods have been described in the context of the DLL system, they may also be used in the PLL system. As in the DLL system, the strobe pulses reduce the effects of multipath signals in the PLL system. However, the strobe pulses increase the noise errors in the PLL system, which is a disadvantage.
Another approach for addressing multipath signals is described by Philip G. Mattos in a paper entitled xe2x80x9cMultipath Elimination for the Low-Cost Consumer GPS,xe2x80x9d from the Proceedings of the 9th International Technical Meeting of the Satellite Division of the Institute of Navigation (Kansas City, Mo. U.S.A.), 1996. Instead of using an xe2x80x9cearlyxe2x80x9d correlator and a xe2x80x9clatexe2x80x9d correlator, this approach uses two xe2x80x9cearlyxe2x80x9d correlators, the output signals of which are called xe2x80x9ce1xe2x80x9d and xe2x80x9ce2xe2x80x9d, respectively. Each correlator correlates the input signal with a replica of the PR-code being tracked, but the replica code signals are offset in time from one another by xe2x85x9 of a chip to xc2xd of a chip. The signal e1 comes from the replica which is earlier in time. The time offset of these replica code signals with respect to the satellite PR-code is adjusted such that the ratio of the e1 signal (the earlier one) to the e2 signal (i.e., e1/e2) is equal to a predetermined fractional amount, such as 0.95 for an xe2x85x9 chip separation in replica codes. The ratio is determined by simulations given certain assumption about the characteristics of the receiver, and a control loop may be set up to minimize the quantity: (e1/e2)xe2x88x920.95. Because the output e1 appears as the numerator in the ratio, and because the ratio is being controlled to a value less than 1, the operating points of both earlier correlators will be positioned on the early edge of the correlation function, where the effects of multipath signals are minimized (by their very nature, reflected multipath signals are received after the main signal). A disadvantage of this method is that susceptible to noise.
When attempting to find ways of reducing the effects of multipath errors, one finds that actions taken to improve the rejection of multipath signals leads to adverse impacts on important characteristics of the receiver, and one is often forced to accept less improvement in multipath rejection for the sake of maintaining other characteristics within acceptable ranges. For example, known correlators that reduce multipath errors have worse indexes of lock. Other actions aimed at reducing multipath errors lead to increases in the noise error or the processor load on the signal processing circuitry.
The developer of such receivers is always faced with the problem of compromising solution choices when taking into account all of the factors and real conditions of the receiver""s operation.
The aim of the present invention is to provide multipath error reduction in PLL and DLL systems while not considerably worsening their lock characteristics or increasing the cost and complexity of the receiver""s hardware.
The present invention encompasses multipath error reduction techniques which enable this error in the DLL systems to be made much less than the error present in known narrow xe2x80x9cearly-latexe2x80x9d correlators, or their corresponding implementations which use strobe representations of the PR-code. The present invention also encompasses multipath error reduction techniques that enable multipath errors in the PLL systems to be reduced. The techniques, when applied to both the DLL and PLL systems work synergistically to further reduce multi-path errors.
Broadly stated, the present invention comprises DLL and/or PLL systems having control signals (Ed and Ep, respectively) which vary with the time delay shift parameter xcex5, which is the difference in time between a chip edge of the PR-code of the broadcast signal and the corresponding edge of the reference PR-code signal (generated by the receiver). The present invention further comprises an asymmetric relationship in one or both of these control signals, such that variation in the control signal is asymmetric about the point steady-state operation (xcex5=xcex50).
In preferred DLL embodiments according to the present invention, the control signal Ed of the DLL system is relatively small and of a first polarity when the receiver""s reference PR-code leads the PR-code of the broadcast signal (xcex5 less than xcex50), and is relatively large and of the opposite polarity when it lags the PR-code of the broadcast signal (xcex5 greater than xcex50). The asymmetric feature enables substantial reduction of multipath errors in the DLL system without degrading the code-locking bandwidth of the DLL system in the range xc2xdxcex94 less than xcex5 less than xc2xdxcex94 (xcex94=one chip period), which has been the case with prior art multipath reduction techniques. Moreover, the asymmetric feature also enables a reduction in probability of the DLL system falsely locking on to a lagging multipath signal.

Methods and apparatuses for reducing multipath errors in the demodulation of pseudo-random coded signals


A scheduling system for chemical processing provides an electronic computer that models the process as a set of tasks with known production ranges. A desired output from the process is back projected through the process to determine production quantities of each task of the process within the production ranges. These values are used to constrain a mixed integer programming evaluation of the schedule which may be used to control operation of the equipment.

The present invention relates to methods of scheduling chemical production equipment in a factory or the like and in particular to an improved computerized method for scheduling equipment related to such chemical production.
The manufacturing of chemicals and materials may provide a system receiving raw materials and processing the materials in multiple batches or tasks, each associated with a process or equipment, to produce a final product. Ideally, each of the tasks may be scheduled to maximize the efficient utilization of the equipment and to minimize the total processing time of the material.
Such scheduling problems are often formulated as mixed integer programming models that may be run on electronic computers. Mixed integer programming (MIP) is a class of linear programming problems widely used in industry to find solutions to optimization problems. In a mixed integer programming problem, some of the unknown variables are integers and some are non-integers.
Such programming problems are generally NP-hard, practically demanding extensive computer processing time that ultimately may be a barrier to a solution or to finding a solution fast enough for practical application to a factory environment.

Computerized system for chemical production scheduling


Methods and apparatus for storing data which employ a hard disk memory media which is operably supported within a cartridge shell to form a disk cartridge. The disk cartridge can be employed in the manner of a tape cartridge wherein the disk cartridge can be stored in a communicatively isolated condition until required for read/write operations whereupon the disk cartridge can be communicatively linked to another device which transmits data to, or receives data from, the disk cartridge. The disk cartridge can adhere to a given tape cartridge form factor so as to enable both tape cartridges and disk cartridges to be employed together in a single automated library system.

Many various types of prior art data storage apparatus and methods are known. Of the known data storage systems, two of the more widely used types are those which comprise tape drives and those which employ hard disk drives. As the respective names imply, tape drives and hard disk drives each employ specific types of media on which to store data. That is, tape drives employ r eels of magnetic tape strips as data storage media, while hard disk drives employ one or more stacked hard disk "platters" as data storage media.
Typically, the magnetic tape type of media is supported on one or more reels which are enclosed in a cartridge shell, or casing. The tape, together with the cartridge shell, is referred to as a "tape cartridge." Such tape cartridges are configured to be selectively placed into a slot, or opening, of a tape drive, wherein the tape is extracted from the cartridge so that data can be read from, and/or written to, the tape. When the reading, and/or writing, of the tape is completed, the tape is wound back into the cartridge, and the tape cartridge is removed from the slot of the tape drive and placed on a storage rack or the like. The cartridge configuration of the tape facilitates ease of handling a great number of tapes, wherein each tape cartridge can be quickly exchanged between a storage position and a tape drive for read/write operations.
Tape cartridges typically adhere to one of a plurality of accepted cartridge form factors. By "cartridge form factor" I mean a given set of standardized physical configurational and dimensional criteria which apply to the design of cartridges. Various specific data storage cartridge form factors have been developed, and include cartridge form factors known by the designations of: DAT (Digital Audio Tape); DDS (Digital Data Storage); DLT (Digital Linear Tape); and LTO (Linear Tape Open) The adherence of tape cartridges to a given known standard cartridge form factor allows for wide spread interchangeability of tape cartridges which adhere to a common form factor.
Often, a plurality of tape cartridges are employed in conjunction with an automated library system or the like. Automated library systems typically comprise storage racks or supports, at least one robotic cartridge handling device, and at least one tape drive. The storage racks are configured to support the plurality of tape cartridges. The robotic cartridge handling device is configured to selectively move given tape cartridges from the storage rack to the tape drive, and to insert the tape cartridge into the slot of the tape drive. While the tape cartridge is in the slot of the tape drive, read/write operations can be performed on the tape. The robotic cartridge handling device is also configured to remove the respective tape cartridges from the tape drive after the read/write operations have been performed on the tape cartridge, and to replace the tape cartridges onto the storage rack.
Thus, a typical automated library system is configured to move tape cartridges between respective stored positions on a storage rack and a tape drive, as required. Generally, a controller or the like is used to control the operation of the automated library system. For example, a controller, when connected in signal communication with the robotic handling device, can be configured to direct the robotic handling device to move a specific, given tape cartridge from its stored position on the storage rack to a tape drive in response to a requirement to retrieve given data which is stored on the given tape cartridge. As is evident, tape cartridges, when used in conjunction with an automatic library system, for example, are relatively well-suited for long-term storage and archiving of large amounts of data. However, one disadvantage of magnetic tape is that data reading/writing operations are relatively slow compared to magnetic hard disks, for example. Moreover, accessing random portions of data from magnetic tape can be significantly slow compared to magnetic hard disks.
Hard disks are generally known to provide exceptionally rapid data storage and retrieval, as well as high levels of storage capacity. Hard disks are typically employed in "disk arrays." A typical disk array comprises a frame or rack that is configured to support a plurality of modules or the like which each contain one or more hard disks along with a disk drive. The modules which contain the hard disks and disk drive are generally configured to be semi-permanently supported on the frame or rack. That is, the modules are generally configured to remain supported in place on the frame or rack and communicatively linked with at least one other device, except for repair and/or replacement of a malfunctioning module in which case the malfunctioning module is communicatively disconnected from the other respective devices and removed from the array. In other words, prior art data storage methods and apparatus which employ a plurality of hard disks are typically limited in regard to the functional use of each hard disk to situations in which all of the hard disks are communicatively linked together so as to be immediately available, on demand, for read/write operations. As a result, the prior art use hard disks for data storage necessitates relatively large and cumbersome disk arrays which comprise a great number of modules.
What are needed then, are data storage methods and apparatus which achieve the benefits to be derived from similar prior art devices, but which avoid the shortcomings and detriments individually associated therewith.

Disk cartridge data storage methods and apparatus

Hewlett-Packard Development Company, L.P.


A method and apparatus for incubating a liquid reagent with target spots on a microarray substrate. A deformable cover is placed over the surface of the microarray substrate having the target spots with the liquid reagent between the microarray substrate and the deformable cover, and a device is used to apply a force to the deformable cover.

The present invention relates generally to methods and systems for hybridizing and/or incubating microarrays.
Microarrays are arrays of very small samples of purified DNA, protein, antibody, or small molecule target material arranged as a grid of up to hundreds or thousands of small spots immobilized onto a solid substrate. FIG. 1A is a top view of a typical microarray. The microarray substrate 10 is typically coated or derivatized uniformly over its top surface 12 to afford chemical or electrostatic binding of small droplets of the target material in solution. The droplets of target solution dry and bind to the top surface 12 of the substrate 10, forming target spots 5 that are is generally from tens to hundreds of microns in diameter. The target spots 5 form a spotted area 7 on the top surface 12 of the substrate 10. The spotted area 7 in the substrate 10 of FIG. 1A is rectangular and has a broken line drawn around it.
A microarray can be used to detect complementary probes. The immobilized target spots on the microarray substrate are exposed to complementary DNA, protein, antigen, or chemical probe samples in liquid solution. The probe materials in solution, which are generally derived from cells, bodily fluids, or combinatorial chemistry libraries, are labeled with fluorescent dyes. The probe materials bind at complementary target spots on the microarray, and the dyes allow for subsequent detection and measurement of the relative concentration of each species of complementary probe material at each target spot. Other detection schemes may be used aside from fluorescence, such as the use of radioactive markers, chemiluminescence, and surface plasmon resonance (SPR).
In some references relating to microarrays, the nomenclature for the immobilized spot material on the microarray substrate (called xe2x80x9ctargetxe2x80x9d material here) and the solution applied to the spots for selective binding assays (called xe2x80x9cprobexe2x80x9d material here) is reversed.
Through a process called hybridization, DNA probe material in solution selectively binds to target spots on the microarray substrate only where complementary bonding sites occur. Similarly, labeled protein probe material only binds selectively to target spots with specific complementary bonding sites; this process is called affinity binding and incubation in protein and antibody assays. Selective reactions of smaller organic or inorganic chemicals (small molecules) to one another or to proteins or DNA can occur in the same way. DNA hybridization and the terminology associated with DNA microarrays will be used throughout this specification, but it is to be understood that the same processes and effects apply to these other types of microarrays.
After the reaction between the probe material and the target material is allowed to occur, quantitative scanning in a fluorescent microarray scanner produces a pixel map of fluorescent intensities. This fluorescent pixel map can be analyzed by special purpose quantitation algorithms to reveal the relative concentrations of the fluorescent probe materials at each target spot on the microarray, thus indicating the level of gene expression, protein concentration, or the like present in the cells from which the probe materials were extracted.
The microarray substrate is generally made of glass that has been treated chemically to provide for molecular attachment of the target spot samples of microarray target material. The substrate 10 can also be made of plastic, silicon, ceramic, metal, or other rigid material. The microarray substrate 10 is also generally of the same size and shape as a standard microscope slide, about 25 mmxc3x9775 mmxc3x971 mm thick. The array area of target spots can extend to within about 1.5 mm of the edges of the substrate, although this array area can also be smaller. Typically, the target spots are approximately round. The target spot diameter can vary from about 50 microns to about 500 microns, depending on the dispensing or spotting technique used to apply the target spots to the microarray substrate. The center-to-center spacing between the target spots on the microarray substrate usually falls into the range of about 1.5 to 2.5 target spot diameters. The target spots are typically printed or xe2x80x9cspottedxe2x80x9d on the top surface of the substrate by pin-type spotting instruments which deposit droplets by a stamping process, where a small ( less than 1 nanoliter) amount of liquid from the wetted end of the pin is transferred to the top surface of the substrate. Alternately, piezo-electric dispensers can dispense drops onto a substrate""s activated surface (called the spotted area of the top surface here) in a manner similar to an ink-jet printer.
The protocols for producing the fluorescently labeled probe solutions can be fairly complex. For differential gene-expression DNA microarrays, exemplary probe preparation steps are:
Tissue or cell isolation
RNA extraction
RNA purification
Reverse transcription of RNA to cDNA
Attachment of the fluorescent label to all species of DNA the solution
Dye teminator cleanup
Addition of buffer to attain desired volume, concentration, pH, etc.
A common type of microarray is used for analyzing differential gene expression. Labeled probe material is prepared from each of two or more tissues or cell types; the RNA/cDNA extracted from each tissue type is labeled with a different dye. Then, the two or more labeled probes are mixed together and applied in solution form to the microarray. The probe mixture is kept in intimate contact with the immobilized target spots on the microarray for some number of hours, typically at a temperature above ambient temperature, to allow the complementary strands of DNA to come into contact with one another and to bind. This process is generally called xe2x80x9cincubation,xe2x80x9d and xe2x80x9chybridizationxe2x80x9d is used to refer to single-stranded DNA segments binding into a double-helix. In contrast, antibody-antigen assay incubation is often carried out at room temperature for times on the order of 5-60 minutes.
FIG. 1B shows a side view of a typical cover glass arrangement that has been used for reacting the probe material with target spots. In the arrangement of FIG. 1B, the microarray substrate 10 is placed on a work surface 14 with the top surface 12 of the microarray substrate 10 having the spotted area 7 facing up. A selected volume of liquid probe solution 16 is then placed as a thin layer on the top surface 12 where the spotted area 7 (not shown) is located, and a cover glass 18 is placed over the liquid probe solution 16. A typical volume of the liquid probe solution 16 is about 15-25 microliters. This small volume of liquid probe solution 16 is deposited on the spotted area 7 of the top surface 12 as a drop. The cover glass 18 placed on top of the drop of liquid probe solution 16 spreads the drop into a thin layer over the spotted area 7 of the top surface 12 with about the same dimensions as the cover glass 18. The layer of liquid probe solution 16 can be about 10-60 microns thick and is kept in place by the capillary effect of being sandwiched between two planar pieces of glass. The dimensions of the spotted area 7 on the top surface 12 and the cover glass 18 are usually smaller than the dimensions of the microarray substrate 10, but in some cases the spots, the cover glass 18 and the liquid probe solution 16 can cover the entire top surface 12 of the microarray substrate 10.
The microarray substrate 10 with liquid probe solution 16 and the cover glass 18 is then placed in a sealed chamber of some sort to prevent the probe from evaporating or drying during incubation. Specially designed hybridization chambers are available for this (a Telechem Hybridization Cassette, for example), but many researchers use common labware such as 50 ml centrifuge tubes or Copeland jars. Often, a laboratory wipe or other absorbent object soaked with water is placed into the hybridization chamber with the microarray and probe liquid to keep the humidity in the chamber near 100% to minimize drying of the probe liquid. Drying of the probe mixture leads to very high non-specific attachment of the fluorescent dye to the microarray, which in turn causes very high background fluorescent signals that may drown out the hybridization signals where drying has occurred.
The molecular event that causes a labeled molecule in the liquid probe solution 16 to bind to one of its immobilized complements on the top surface 12 requires that the two molecules be in intimate contact. With the cover glass method described in connection with FIG. 1B, diffusion is the only vehicle for molecular movement. In other methods, a stick-on cap can be affixed over a substrate with liquid probe solution, and then the liquid probe solution can be agitated during incubation by shaking the combination of the substrate and stick-on cap, or by pumping liquid to and from under the stick-on cap.
One embodiment of the invention is a method for incubating a liquid reagent with target spots on a first surface of a microarray substrate. In this embodiment, the liquid reagent is confined between a deformable cover and the surface of the substrate having the target spots. The deformable cover is then deformed by applying a force to the cover with a deflector. The force can vary in location of application, magnitude, or in a combination of magnitude and location of application. The deflector, which can be a roller, can apply a force to the deformable cover in different locations along the deformable cover, thus agitating the liquid reagent and aiding in incubation. Deformation of the deformable cover can be in either a top region or in a gasket of the cover.
In an alternative method for incubating reagents in accordance with the invention, a deformable cover is placed upon a mechanical support or a work surface. In one embodiment, the deformable cover is placed upside-down on the work surface. Liquid reagent is then placed on the deformable cover, either manually or automatically. The microarray substrate is then placed over the cover with the liquid reagent, thus forming a reaction chamber between the liquid reagent and the substrate. The microarray substrate and the deformable cover are then moved to agitate the liquid reagent. A force can be applied to the deformable cover with a deflector to agitate the liquid reagent in the reaction chamber. Upon application of the force, the deformable cover can deform to move the liquid reagent in the reaction chamber. Additionally, when the liquid reagent is placed in the cover, the amount of liquid reagent can be applied so that an air bubble remains within the reaction chamber upon application of the substrate over the deformable cover. Upon application of the force to the deformable cover, the air bubble can aid in the agitation of the liquid reagent.
Another embodiment of the invention is an apparatus for incubating a liquid reagent with target spots on a first surface of a microarray substrate. In this embodiment, the apparatus can include a deformable cover and a deflector. The deformable cover is adapted to seal the liquid reagent between the deformable cover and the first surface of the microarray substrate, thus forming a reaction chamber. The deflector is designed to apply a force to the deformable cover to agitate the liquid reagent within the reaction chamber.
Yet another embodiment of the invention is also an apparatus for incubating a liquid reagent with target spots on a first surface of a microarray substrate. In this embodiment, the cover includes a substantially rigid lid and a gasket that deforms more easily than the lid. A first actuator and a second actuator are used to apply forces to the cover, thus deforming the gasket of the cover. Upon alteration of the force produced by the first actuator and the force produced by the second actuator, the lid of the cover tilts, thus producing a flow of liquid reagent over the microarray substrate. This flow of liquid reagent can aid in the reaction during incubation. In one embodiment, the sum of the force produced by the first actuator and the force produced by the second actuator remains substantially constant as the two forces vary. In this manner, when one of the forces increases, the other force decreases by approximately the same magnitude. This substantially constant sum of the forces can ensure that a sufficient force remains on the cover to keep the seal formed between the gasket and the substrate so that liquid reagent does not escape during the incubation process.

Method and apparatus for incubation of a liquid reagent and target spots on a microarray substrate


In a mobile communication system, even when cells formed by fixed radio base stations are separated from each other, the switching operation between the cells is easily carried out to conduct continuous communication. A first-end radio device mounted in a first-end section of a mobile unit and linked with one of fixed radio base stations or a last-end radio device mounted in a last-end section of a mobile unit and linked with one of fixed radio base stations is selected. A communication network is established between the first-end or last-end radio device thus selected and a plurality of mobile terminals in the mobile unit. This makes it possible to construct a communicable zone (a virtual cell) on the mobile unit and hence elongates the ranges of cells formed by the base stations.

1. Field of the Invention
The present invention relates to a mobile communication system and a communication control method for use with the system including cells of which each defines a predetermined radio wave arrival range of radio waves from a fixed base station associated with the cell, and in particular, to a mobile communication system and a communication control method for use with the system suitable for a mobile unit or module such as a train moving at a high speed.
2. Description of the Prior Art
To guarantee wide uses of mobile communication terminal devices using radio or wireless communication, communication enterprises have been endeavoring to develop areas for the terminal devices. Recently, the areas have been broaden beyond indoor areas to include zones such as places in a subway train and a tunnel. The terminal device can be used in a moving train and even in a high-speed mobile unit such as a train of the Japanese rapid line or Shinkansen today. Therefore, it is expected that many people uses such communication terminals in a moving train. For this purpose, a type of network business is being developed using communication terminals in a moving train. At present, it has been desired to develop a system in which the terminal in a car moving at a high speed can continuously keep a communication line to a party of communication.
For example, Japanese Patent Laid-Open No. Hei 11-298967 filed before the present specification describes a technique in which a wireless mobile station which can be connected to a public communication line and/or a leased communication line to communicate with an outer-vehicle wireless base station disposed outside a vehicle and an inner-vehicle wireless base station to communicate with the mobile station and a wireless terminal device in a vehicle are arranged so that signals are transmitted from the vehicle to the outer-vehicle base station.
Moreover, Japanese Patent Laid-Open Ser. No. 09-327057 proposes a mobile communication system in which to enable communication in a running train by use of a mobile terminal device (PS) for a micro-cell system, there are disposed a plurality of inside wireless stations (CS) in a train for a micro-cell system to communicate with the mobile terminal so that a wireless base station (BS) disposed outside of the train is connected to the inside stations (CS).
Japanese Patent Laid-Open No. Hei-10-164640 describes a mobile communication system in which a communicating device to communicate with a mobile terminal in a mobile unit is arranged in a place of a first end thereof and in a place of a last end thereof. When the mobile unit moves from a first position to a second position, the communicating devices at the first and last ends of the mobile unit conduct a change-over operation with respect to an external fixed base station to continuously retain a linked state in which each of the communicating devices establishes a link with the fixed base station.
In the conventional cell configuration of the fixed wireless base stations, cells are adjacent to each other or overlap with each other to continuously use a communication line between a mobile wireless device and a fixed wireless station.
As can be seen from FIG. 16, for example, when a mobile wireless device 100 in a linked state for a fixed wireless base station A, namely, in a state capable of communicating with the base station A moves in a running direction to a position outside a cell a configured by the base station A, the device 100 enters a non-linked or disconnected state for the base station A, i.e., a state in which the device 100 cannot communicate with the base station A. That is, the link between the wireless device 100 and the base station A is disconnected and hence communication is not possible therebetween. To continuously keep the communication of the wireless device 100 in this situation, the system is configured so that the cell a of the base station A is contiguous to a cell b constructed by a fixed wireless base station B or the cell a overlaps with the cell b as shown in FIG. 17. Thanks to this configuration, the link between the mobile device 100 and the base station A is released and a new link is prepared between the device 100 and the base station B in the situation described above. As a result, the communication line being used by the wireless terminal device 100 is kept connected.
However, as can be seen from FIG. 17 showing the cell configuration of the prior art, the cells (a and b) are adjacent to each other or overlap with each other in consideration of each size of a radio signal receivable range of each fixed wireless base station and a distance between the base stations. That is, the cells are configured only according to the fixed base stations. To reduce the number of base stations in this case, it is favorable to separate the cells (a and b) from each other as shown in FIG. 18. However, in accordance with Japanese Patent Laid-Open Nos. Hei-11-298967 and Hei-09-327057, when the cells (a and b) are apart from each other, a non-communicable zone in which communication is not possible between a fixed wireless base station and the mobile wireless device appears between the cells a and b. As a result, the mobile wireless device 100 cannot continuously conduct communication.
In the technique described in Japanese Patent Laid-Open No. Hei-10-164640, even when the cells (a and b) are separated from each other as shown in FIG. 18, it can be considered that the first and second mobile communication units become alternately linked with fixed wireless base stations to continuously conduct communication. However, as implied by FIGS. 1 to 5, the technique has an object in which the first and second mobile communication units are alternately set to the linked state, namely, either one there of is in the communicable state to continuously carry out communication when the cells overlap with each other. When either one of the mobile communication units enters a linked state, a switching section releases the linked state of the other one thereof into a non-linked state so that only one of the communication units is in the linked state. This complicates control processing of the switching section and hence there exits a fear of delay in the switching operation to establish a linked state in the mobile communication unit.

Handoff method for a communication system of a train


The present invention discloses the use of a mutant Leishmania as a suicidal vaccine wherein the mutant Leishmania is responsive to external signals to become porphyric and commit suicidal cytolysis. The mutant can be selected from natural Leishmania species or constructed by genetic engineering.

The present invention discloses the use of a mutant Leishmania as a suicidal vaccine wherein the mutant Leishmania is responsive to external signals to become porphyric and commit suicidal cytolysis.
Leishmania spp. are flagellated trypanosomatid protozoa commonly known as trypanosomes. Essentially all of them are parasites, of which overwhelming majority are non-pathogenic to humans, but live in other animals and sometimes in plants. However, certain species of Leishmania are pathogenic to their hosts, resulting in leishmaniasis. The best known pathogenic species are vector-borne Trypanosoma spp., which cause African Sleeping Sickness as extracellular parasites in body fluids and South American Chagas disease as parasites with both extracellular and intracellular phases. Recently, Leishmania spp. have attracted attention for causing "Baghdad boils" via sand fly bites among soldiers sent to Iraq and Afghanistan.
Leishmania spp. are uniquely suitable among trypanosomes to serve as a live vaccine model for the following reasons:
First, Leishmania spp. naturally infect antigen-presenting cells (APC), i.e., dendritic cells and macrophages, hence inherently suitable for homing vaccines to a desired destination. Leishmania not only infect macrophages but utilize them as their exclusive host cells by residing in their phagolysosomes (Chang and Dwyer, 1976). This is the very site where antigens/vaccines are processed for presentation via the lysosomal major histocompatibility complex (MHC) Class II pathway and also via the cytosolic MHC Class I pathway by cross-presentation (Houde et al. 2003). This APC-homing ability of Leishmania makes them exceptionally attractive for consideration as a live vaccine model. Micro-organisms, which share with Leishmania this specific feature, are very few and limited to pathogenic bacteria, e.g., Coxiella burnetii, Legionella pneumophilia and Mycobacterium leprae. Unlike these microbes, Leishmania have a number of advantages as single-cell eukaryotes.
Second, Leishmania spp. are amenable to laboratory maintenance in culture and in animal models. They grow in vitro as flagellated motile "promastigotes", which normally live as extracellular parasites in the gut of blood sucking sand flies. Continuous cultivation of promastigotes is readily achievable for most species by using tissue culture media commercially available for mammalian and insect cells (Chang and Hendricks, 1985). These promastigotes differentiate into infective or "metacyclic" forms in fly gut or as they reach stationary phase in culture. They further differentiate into non-motile "amastigotes"—the intra-macrophage stage normally found in the mammalian hosts. Some species, especially L. amazonensis and L. mexicana, grow readily and continuously free of macrophages as "axenic amastigotes" under suitable conditions at acidic pH and mammalian body temperature (Hodgkinson et al., 1996). These species also grow continuously as intracellular amastigotes in macrophage cell lines, e.g., J774 series (Chang, 1980; Chang, 1978; Chang and Hendricks, 1985). These and other species can be further passaged cutaneously or viscerally in rodents, e.g., hamsters and mice (Chang and Hendricks, 1985).
Third, non-pathogenic Leishmania spp. exist, originating from lizards, e.g., L. tarentolae and from rodents, e.g., L. enriettii of guinea pig and L. turanica of the great gerbil in Gobi desert. There is documented evidence for these species to produce no disease in human volunteers at least for L. gerbilli (Strelkova, 1991), despite it is phylogenetically closely related to L. major (FIG. 1). L. major is well-known to cause self-healing simple cutaneous leishmaniasis (CL). This is the least pathogenic one among 2 dozens or so additional species of known human pathogens in both Leishmania and Viannia subgenus (Shaw, 1994). Some of them cause not only CL but also facial disfiguring mucocutaneous leishmaniasis (MCL), e.g., L. braziliensis and L. panamensis or the potentially fatal visceral leishmaniasis (VL), e.g., the Indian kala-azar caused by L. donovani and the Mediterranean infantile VL (IVL) caused by L. infantum. Included for the present invention are well-established laboratory species as well as field isolates appropriately genotyped (see legend to FIG. 1), ranging from totally non-pathogenic to highly virulent species.
Fourth, human populations have been successfully vaccinated against cutaneous leishmaniasis with lesion-derived live amastigotes of L. major. This is known as a time-honored procedure of "Leishmanization" (i.e., vaccination of children with virulent parasites from diseased patients). It has been practiced for centuries and proven effective to elicit life-long protective immunity against CL in the Middle East and Central Asia. Iranian and Russian workers have documented this more scientifically. From 1978 to 1989, Mohebali et al. had "leishmanized" or vaccinated about 2 million individuals in their upper arms with a live L. major culture originally from a Great Gerbil in Iran. This "vaccination" confers protective immunity in >90% of the leishmanized individuals, but the procedure takes 10-15 months, during which period "vaccinees" develop full-blown lesions followed by spontaneous healing, just like the natural infection (Nadim et al., 1997). In addition, non-healing lesions occurred in 1-2/10,000 cases. Similar results were reported in Central Asia using a different strain of live L. major by Dr. Leonid Krasnonos et al. in Isaev Institute of Medical Parasitology, Samakan, Uzbekistan. Thus, "Leishmanization" has a proven track record of effectiveness in contrast to the uncertain benefits of BCG vaccination for tuberculosis. Leishmania also compare favorably over BCG to serve as potential vehicles to deliver add-on vaccines, since these and other related trypanosomes are readily cultivable and since they are genetically efficient and versatile to express foreign genes. One principal disadvantage common to all live vaccine models is the issue of residual pathogenicity, as described for "Leishmanization". An important aspect of the present disclosure is to address this issue by using transgenic Leishmania responsive to external signals to commit suicidal cytolysis.
Fifth, there is a substantial body of information available for the immune response of animals to Leishmania infection. Experimental leishmaniasis has been extensively used for elucidating rodent immunogenetics and immunobiology, especially the BALB/c mouse-L. major model (Gumy et al., 2004). The use of this model has indeed led to the significant discovery in the dichotomy of animal immune response via Th1 and Th2 pathways (Locksley et al., 1987; Scott et al., 1988). The regulation of these pathways in relation to protective immunity is still under intensive investigation (Etges and Muller, 1998), including the use of different Leishmania-mouse combinations (Lipoldova et al., 2002). There have been additional efforts to extend such investigation to hamster and primate models (Melby et al., 2001; Olobo et al., 2001; Probst et al., 2001; Requena et al., 2000). This wealth of knowledge has proven its value in current efforts to develop Leishmania DNA-based and recombinant peptide vaccines as well as using sand fly saliva antigens (Ahmed et al., 2004; Belkaid et al., 1996; Belkaid et al. 1998; Campbell et al., 2003; Campbell et al., 2004; Coler et al., 2002; Kamhawi et al., 2000; Morris et al.,; 2001; Reed, 2001; Valenzuela et al., 2001).
Sixth, Leishmania spp. are amenable to genetic manipulations for expressing endogenous or foreign genes via transfection by electroporation. The genome project has been essentially completed for L. major. This and other species possess all the necessary machineries of eukaryotic types not only for gene replication, mRNA transcription and protein translation but also for post-translational modifications of proteins. The last cellular events, which may have some importance in vaccine presentation, are absent in bacterium-based live vaccine models, e.g., Salmonella and BCG. There are at least 6 different markers available for selection of transfectants in conjunction with the use of Leishmania-E. coli shuttle vectors. The principal is the pX series (Freedman and Beverley, 1993; Goyard and Beverley, 2000). In addition, we have developed p6.5 using Leishmania endogenous N-acetylglucosamine-1-phosphate transferase gene (nagt) as a selectable marker for tunicamycin (TM)-resistance (Chen et al., 2000, Kawazu et al., 1997; Liu and Chang, 1992; Sah et al., 2002; Somanna et al., 2002). There have been numerous reports of Leishmania gene knock-outs and knock-ins by homologous recombination (Alexander et al., 1998; Burchmore et al., 2003; Ilg et al., 2001; Cruz et al., 1991; Spath et al., 2003, 2004; Zhang et al., 2003). Such genetic manipulations have been routinely carried out by us (Chen et al., 2000; Chen et al., 1999; Sah et al., 2002) and will be used for the proposed studies.
Seventh, vaccination of animals by genetically modified Leishmania has produced favorable outcome. Mice were protected against infection by L. major or L. mexicana when immunized with their respective knockouts of house-keeping genes, e.g., dhfr (Titus et al., 1995) or virulence genes, i.e., Ipg 1, lpg2 and cysp (Alexander et al., 1998; Ilg et al., 2001; Spath et al., 2003, 2004).

Rosalind Franklin University of Medicine and Science


A “C” clamp that can be securely fastened vertically on to a counter top. The “C” clamp having a smaller clamp mounted horizontally to the upper area of the larger vertical clamp. The smaller horizontal clamp having a metal strap designed to fasten an appliance cord.

(1) Field of the Invention
Child Safety. Many years ago butcher block type table were used in kitchens for rolling out dough or for cutting different foods, or for other work needs around the kitchen. Over the years these work islands or peninsulas have evolved to where sinks and range tops are now placed in the tops, which did not cause any problems.
But with the advent of small electric appliances [mixers, fry pans, small deep fryers] electrical outlets were required. Many of these work tops have no back splash where electrical outlets [receptacles] could be installed. So the National Fire Protection Association along with the National Electrical Code committees spelled out where the outlets were to be placed. The receptacles could not be place in the top of the counters for they would get contaminated with food and liquids, so they had to be placed on the sides of the island or peninsula cabinets. (See attachment page 70-64 N.E.C.)
This situation has now created a HAZARD for little children. They can now reach the appliance cord and pull the HOT fry pan down upon themselves.


Drive arrangement for motorized actuation of a functional element in a motor vehicle, having at least one drive, the drive having a drive motor and a spindle-spindle nut gear connected downstream of the drive motor for producing linear drive movements, the spindle-spindle nut gear having a spindle with an outside thread and a spindle nut with an inside thread, the linear drive movements being a motion of the spindle nut parallel to a spindle axis. the spindle-spindle nut gear has at least one telescoping sleeve with an inside thread and an outside thread. The at least one telescoping sleeve, spindle and spindle nut are arranged in a telescoping manner being screwed into one another with each outside thread forming a thread pairing with an respective inside thread. An alternative spindle-spindle nut gear has the outside thread and form a ball groove thread pairing with a variable thread pitch.

1. Field of the Invention
The invention relates to a drive arrangement for motorized actuation of a functional element in a motor vehicle with at least one drive, the drive having a drive motor and a spindle-spindle nut gear connected downstream of the drive motor for producing linear drive movements, the spindle-spindle nut gear having a spindle with an outside thread and a spindle nut with an inside thread, and the linear drive motion being moving the spindle nut parallel to the spindle axis.
2. Description of Related Art
Within the framework of enhancing the ease of operation in motor vehicles, drive arrangements of the type under consideration are becoming more and more important. The functional elements which can be moved by a motor here are, for example, hatches, especially rear hatches, rear covers, side doors or lifting roofs, vehicle seats or the like. In addition to high reliability and low costs, the compactness of such a drive arrangement plays an important part.
The known drive arrangement underlying the invention (U.S. Pat. No. 6,516,567) has a drive arrangement for motorized actuation of the rear hatch of a motor vehicle with two drives which act on the two side edges of the rear hatch by drive engineering. The drives each have a drive motor and a spindle-spindle nut gear connected downstream of the drive motor. The spindle-spindle nut gear, as is conventional, has a spindle with an outside thread which runs in the inside thread of a spindle nut. Driving the spindle allows the spindle-spindle nut gear to be moved between a retracted and an extended state. A linear drive motion, specifically motion of the spindle nut, parallel to the spindle axis, can thus be comparatively easily implemented.
The disadvantage in the known drive arrangement is that the spindle-spindle nut gear has a considerable length in the retracted state. This is due to the fact that the length of the spindle must correspond at least to the length of the desired feed path. This costs installation space in the interior of the vehicle which is fundamentally dimensioned to be tight. The large extension of the drive arrangement is also a problem in terms of aesthetics.
Furthermore, it must be considered that each rear hatch of a motor vehicle has a quite defined closing and opening characteristic. This means that the expenditure of force necessary to open or close the hatch changes when viewed over the entire closing and opening motion. For example, it can be that, to open the rear hatch of a motor vehicle, initially, an especially high force is necessary until gas pressure dampers which may be present support the opening motion. However, it can also be that these gas pressure dampers are not provided, so that the expenditure of force necessary for the opening motion is maximum when the hatch is almost completely opened. The design of the spindle-spindle nut gear, on the one hand, and the drive motor, on the other hand, therefore, constitutes a compromise in the known drive arrangement, in any case. This compromise leads to high costs since the drive motor is over-dimensioned for a considerable part of the positioning motion of the rear hatch.


There are provided a tin-plated product which has a zinc plating layer on the surface thereof and which has good corrosion resistance and good adhesion of the zinc plating even if the connecting portion of a terminal of the tin-plated product to an electric wire of aluminum or an aluminum alloy is not processed during press fitting such as swaging (or caulking) when the tin-plated product is used as the material of the terminal which is to be connected to the electric wire by press fitting, and a method for producing the same.

Electric wires of copper or copper alloys are conventionally used as electric wires such as automotive wire harnesses, and tin-plated products of copper or copper alloys plated with tin are conventionally used as the materials of terminals which are to be connected to the electric wires.
In recent years, in order to improve fuel efficiency due to the weight saving of automotive vehicles, electric wires of aluminum or aluminum alloys having lower specific gravities than those of copper and copper alloys are used as the electric wires such as automotive wire harnesses.
However, if a terminal of a tin-plated product is connected to an electric wire of aluminum or an aluminum alloy by press fitting such as swaging (or caulking), there is some possibility that galvanic corrosion (for allowing a less-noble metal to melt) may be caused by bringing dissimilar metals into contact with each other, the potential difference between the dissimilar metals being large.
For that reason, a preservative or resin is applied on the connecting portion of the terminal to the electric wire for preventing galvanic corrosion. However, the application of such a preservative or resin lowers the productivity of the tin-plated product to increase the production costs thereof.
As a terminal for preventing galvanic corrosion, there is proposed a terminal having an electric-wire connecting portion having a core-wire barrel portion for connecting a core wire of a first metal (an aluminum material), which is exposed at one end of an electric wire, to the terminal by swaging (or caulking), the terminal being made of a second metal (a copper material) having a smaller ionization tendency than that of the first metal, the electric-wire connecting portion being plated with a third metal (zinc) having an intermediate ionization tendency between those of the first and second metals before swaging (or caulking) the core-wire by the core-wire barrel portion, and the plating layer on the electric-wire connecting portion of the core-wire barrel portion being broken during swaging (or caulking) (see, e.g., Patent Document 1). Prior Art Document(s)

Tin-plated product and method for producing same


A method, and apparatus implementing the method, encodes bits to be transmitted over a channel. The channel may be a single carrier or a multi-carrier channel. Bits are encoded based on a constellation that has a self-similarity property and also has an improved bit error rate. The constellation was iteratively generated using a mirroring technique. In addition, a method, and apparatus, implementing the method, decodes bits that were received from a channel. The bits are decoded for a constellation that has a self-similarity property and that was generated using the mirroring technique.

Demand for digital subscriber line (DSL) service across existing twisted pair copper wires between a central office and a remote location is increasing. Typically, DSL services operate in accordance with DSL standards recommended by the Telecommunication Standardization Sector of the International Telecommunication Union (ITU). A family of DSL Recommendations from the ITU includes: G.992.1, G.992.2, G.991.1, G.996.1, G.994.1, G.997.1 and G.995.1. Recommendation G.995.1 provides an overview of these standards. Recommendations G.991.1, G.992.1, G.992.2 have developed techniques for transmitting a range of bit rates over the copper wires of the local network including high bit rates at relatively short distances, and lower bit rates at longer distances. In particular, the G.992.1 and G.992.2 recommendations are based on asymmetric digital subscriber line technology that has different data rates in each direction of transmission. The G.992.1 recommendation is referred to as G.dmt and uses a splitter to filter the voicegrade signals at the remote location. The G.992.2 recommendation is referred to as G.lite and does not use a splitter. Recommendations G.994.1, G.996.1 and G.997.1 support the G.992.1 and G.992.2 recommendations by providing common handshake, management and testing procedures. These standards allow substantial flexibility in implementation.
DSL services typically use a discrete multi-tone (DMT) signal to transmit data. A DMT signal has multiple subchannels, each of which is assigned a frequency, also referred to as a carrier frequency or a tone, belonging to a discrete frequency band. Because individual subchannels operate at different frequencies, the subchannels may have different operating characteristics. For instance, more power may be used at higher frequencies. In addition, different numbers of bits may be loaded on different subchannels in accordance with their capacity, which depends on frequency, power, signal-to-noise ratio and transmission line characteristics. Subchannels that do not meet or exceed a minimum signal-to-noise ratio are not used. When initiating a DSL communication session, in the DSL modem, an initialization procedure at the receiver determines a number of bits to be grouped into a symbol for each subchannel, that is, a number of bits per subchannel, and exchanges that information with the transmitting DSL modem.
Quadrature amplitude modulation (QAM) is a technique to encode multiple bits into a QAM symbol. Each QAM symbol represents a distinct combination of bit values using a distinct combination of amplitude and phase of the carrier waveform based on distinct X and Y coordinates associated with respective bit values. Each QAM symbol is represented by a QAM waveform.
Referring to FIG. 1, a signal space diagram depicts an exemplary constellation 100 having a set of constellation points 102. Each constellation point 102 represents a distinct QAM symbol. The constellation points are mapped along an x-axis (X) 104 and a y-axis (Y) 106. Each constellation point 102 is associated with a distinct label which represents a respective distinct combination of bit values for a predetermined number of bits b. The label is also referred to as a tuple. Each constellation point 102 is also associated with a distinct (X, Y) coordinate. FIG. 1 depicts a constellation 100 having four constellation points 102 in which the number of bits b is equal to two. For example, the constellation point having the label 0 has an X coordinate equal to 1 and a Y coordinate equal to 1; and the constellation point having the label 3 has an X coordinate equal to −1 and a Y coordinate equal to −1.
In quadrature-amplitude modulation, the amplitudes of two quadrature carriers are modulated and the carriers are combined. The X coordinate represents the amplitude of a first carrier, and the Y coordinate represents the amplitude of a second carrier that is shifted in phase by 90° with respect to the first carrier. For example, the first carrier is a sine wave, while the second carrier is a cosine wave. Each constellation point 102 represents a distinct combination of the modulated carriers and thus a distinct QAM symbol.
A constellation encoder encodes groups of bits (tuples) into the (X, Y) coordinates of a QAM symbol. For example, tuples of four bits have sixteen possible distinct values. When encoding tuples of four bits, a constellation will have sixteen distinct constellation points, one constellation point for each value. The constellation encoder maps each of the sixteen possible combinations of values of the four bits to a distinct constellation point which has distinct (X,Y) coordinates which are used to produce the QAM symbols. The number of bits in the tuple, that is, the number of bits encoded, is referred to as the constellation size b.
In other words, for a given QAM channel, or in broadband communications for a given QAM subchannel, one typical constellation encoder selects an odd-integer point (X,Y) from a square constellation based on the values of the binary b-bit tuple, {vb-1, vb-2, . . . , v1, v0}. In the constellation, the b bits of the tuple are associated with an integer label having a binary representation of {vb-1, vb-2, . . . , v1, v0}. In FIG. 1, for example, when b=2, the four constellation points have labels of 0, 1, 2 and 3. Typically, the integer values of the X and Y coordinates of the constellation point are determined from the b bits such that the values of X and Y are odd integers having two's complement binary representations of { . . . , 1} and { . . . , 1), respectively. The most significant bit of X and of Y is the sign bit.
In digital multi-carrier systems, the digital information is transformed by a modem into an analog form that is essentially a sequence of DMT symbol waveforms. Each DMT symbol bears information in an array of zeroes and ones. The digital multi-carrier system is a channel having i subchannels. Each subchannel is associated with a distinct carrier frequency. The channel has i sub-arrays, one associated with each subchannel. Each sub-array has bi bits. Therefore, bi represents a number of bits per subchannel i. Each sub-array corresponds to a QAM waveform representing a constellation point in a 2b,-point constellation. A DMT symbol waveform is the superposition of these QAM waveforms. Each subchannel is characterized by a signal-to-noise ratio γi, where γi represents the signal-to-noise ratio (SNR) at the ith carrier frequency.
In DMT systems, each subchannel has a constellation encoder. Typically, in DMT systems, equal error protection is applied, and the number of bits per subchannel bi is determined such that, for each subchannel, the bit error rate should not exceed a target bit error rate prior to decoding and retransmission pb.
The number of bits per subchannel is selected while executing an initialization procedure. During initialization, the channel is analyzed and parameters are determined and exchanged. The ITU recommendations for G.lite and G.dmt set a target bit error rate (BER) standard of 10−7. The number of bits per subchannel are selected based on, at least in part, a target bit error rate standard and an average number of erroneous bits per QAM symbol.
In practice, the bit error rate for data transmitted using conventional G.992.1 and G.992.2 constellations may fluctuate. This fluctuation in the bit error rate reduces the number of bits per subchannel. Therefore, a method and apparatus are needed to reduce fluctuations in the bit error rate and thus increase the number of bits per subchannel.

Method and apparatus for improving error control properties for encoding and decoding data


A drive unit drives a wafer table in a Y-axis direction based on a measurement value of an encoder that measures position information of the wafer table in the Y-axis direction and based on known correction information in accordance with position information of the wafer table in a non-measurement direction (e.g. Z, θz and θx directions) that is measured by an interferometer at the time of the measurement by the encoder. That is, the wafer table (a movable body) is driven in the Y-axis direction based on the measurement value of the encoder that has been corrected by correction information for correcting a measurement error of the encoder that is caused by a relative displacement of a head and a scale in the non-measurement direction. Accordingly, the movable body can be driven with high accuracy in a desired direction while measuring the position by the encoder, without being affected by the relative motion between the head and the scale in directions other than a direction to be measured (measurement direction).

Field of the Invention
The present invention relates to movable body drive systems and movable body drive methods, pattern formation apparatuses and methods, exposure apparatuses and methods, device manufacturing methods, and decision-making methods, and more particularly to a movable body drive system and a movable body drive method that drive a movable body along a predetermined plane, a pattern formation apparatus equipped with the movable body drive system and a pattern formation method using the movable body drive method, an exposure apparatus equipped with the movable body drive system and an exposure method using the movable body drive method, a device manufacturing method using the pattern formation method, and a decision-making method in which correction information of measurement values of an encoder system that measures position information of a movable body in a predetermined direction is decided.
Description of the Background Art
Conventionally, in a lithography process in the manufacturing of microdevices (electron devices) such as semiconductor devices and liquid crystal display devices, exposure apparatuses such as a reduction projection exposure apparatus by a step-and-repeat method (a so-called stepper) and a reduction projection exposure apparatus by a step-and-scan method (a so-called scanning stepper (which is also called a scanner) are relatively frequently used.
In these types of exposure apparatuses, in order to transfer a pattern of a reticle (or mask) to a plurality of shot areas on a wafer, a wafer stage that holds the wafer is driven in XY two-dimensional directions by, for example, a linear motor or the like. In particular, in the case of the scanning stepper, not only the wafer stage but also a reticle stage is driven by a linear motor or the like in a scanning direction in a predetermined stroke. Generally, position measurement of the reticle stage or the wafer stage is performed using a laser interferometer whose measurement values have stability for a long period and which has a high resolution.
However, more accurate position control performance has been required due to finer patterns to cope with higher integration of semiconductors, and recently the short-term fluctuation of the measurement values caused by variation in the temperature of the atmosphere on the beam optical path of the laser interferometer has been accounting for a large share of the overlay budget.
Meanwhile, as an apparatus other than the laser interferometer to be used for position measurement of a stage, an encoder can be cited, but because the encoder uses scales and the scales lack mechanical long-term stability (due to drift of scale pitch, fixed position drift, thermal expansion, and the like), and therefore, the encoder suffers from the disadvantages of lacking the linearity of the measurement values and being inferior in the long-term stability, compared with the laser interferometer.
In view of the disadvantages of the laser interferometer and the encoder as described above, various types of apparatuses that measure the position of a stage using both a laser interferometer and a position detection sensor (encoder) that uses a diffraction grating have been proposed (refer to Kokai (Japanese Unexamined Patent Application Publications) No. 2002-151405 and No. 2004-101362, and the like.)
Further, although a measurement resolution of a conventional encoder was inferior to that of an interferometer, recently encoders having the measurement resolution equal or superior to the laser interferometers have come out (e.g. refer to Kokai (Japanese Unexamined Patent Application Publication) No. 2005-308592 and the like), and the technique of combining the laser interferometer and the encoder has been gathering attention.
However, for example, in the case the encoder is used for position measurement of a wafer stage within a moving plane in an exposure apparatus, even when the position of a stage on which a scale (grating) is arranged is measured using one encoder head, if the relative motion between the head and the scale occurs in a direction other than a direction to be measured (measurement direction), the variation in the measurement value (count) is detected and a measurement error occurs in most cases. In addition, in the case the encoder is actually applied to a wafer stage of an exposure apparatus, because a plurality of encoder heads need to be used for one scale, there is also the inconvenience that an error occurs in a count value of the encoder due to, for example, the difference in gradient (tilt of the optical axis) between the encoder heads, and the like.

This patent is subject to a terminal disclaimer.

Movable body drive system and movable body drive method, pattern formation apparatus and method, exposure apparatus and method, device manufacturing method, and decision-making method


Aspects of port empty transition scheduling are described herein. In one embodiment, when one or more cells are added to a queue in a network communications device, an enqueue indicator is generated. The enqueue indicator identifies a number of cells added to the queue. With reference to the enqueue indicator, a queue scheduler maintains a count of cells enqueued for communication and issues a port pick credit for a port of the network communications device. A port scheduler schedules a pick for communicating over the port with reference to the port pick credit and forwards the pick to the queue scheduler. In turn, the queue scheduler forwards a queue pick to the queue, and at least one of the cells is forwarded to dequeue logic. According to aspects of the embodiments described herein, empty port scheduling inefficiencies may be avoided and network throughput increased.

Among other functions, a network component, such as a network router, switch, etc., routes or switches data from a source to a destination. For example, a network switch may receive network packets on one or more input ports and route or switch these packets to one or more output ports. According to various network communications protocols, ingress packets which enter the switch may be scheduled for communication by the switch as egress packets according to suitable packet priorities for reliable data transfer.
In this context, as packets are received, a switch processes the packets according to packet priorities and protocols, so that the packets may be ultimately transmitted toward network destinations. Especially when a network component operates during a time of high packet processing demand, it is important for the network component to operate efficiently. In certain cases, the rate at which data is received by the network component may even exceed the network component's ability to process and transmit that data. In some worst-case situations, a network component may drop packets if the rate at which data is received by the network component exceeds the network component's ability to process and transmit that data and, for example, a buffer or memory overrun occurs.


Blood sugar levels are measured non-invasively based on temperature measurement. Non-invasively measured blood sugar level values obtained by a temperature measurement scheme are corrected by blood oxygen saturation and blood flow volume, thereby stabilizing the measurement data.

1. Field of the Invention
The present invention relates to a non-invasive blood sugar level measuring method and apparatus for measuring glucose concentration in a living body without blood sampling.
2. Background Art
Hilson et al. report facial and sublingual temperature changes in diabetics following intravenous glucose injection (Non-Patent Document 1). Scott et al. discuss the issue of diabetics and thermoregulation (Non-Patent Document 2). Based on such researches, Cho et al. suggests a method and apparatus for determining blood glucose concentration by temperature measurement without requiring the collection of a blood sample (Patent Documents 1 and 2).
Various other attempts have been made to determine glucose concentration without blood sampling. For example, a method has been suggested (Patent Document 3) whereby a measurement site is irradiated with near-infrared light of three wavelengths, and the intensity of transmitted light as well as the temperature of the living body is detected. Then, a representative value of the second-order differentiated value of absorbance is calculated, and the representative value is corrected in accordance with the difference between the living body temperature and a predetermined reference temperature. A blood sugar level corresponding to the thus corrected representative value is then determined. An apparatus is also provided (Patent Document 4) whereby a measurement site is heated or cooled while monitoring the living body temperature. The degree of attenuation of light based on light irradiation is measured at the moment of temperature change so that the glucose concentration responsible for the temperature-dependency of the degree of light attenuation can be measured. Further, an apparatus is reported (Patent Document 5) whereby an output ratio between reference light and the light transmitted by an irradiated sample is taken, and then a glucose concentration is calculated using a linear expression of the logarithm of the output ratio and the living body temperature.
[Non-Patent Document 1] R. M. Hilson and T. D. R. Hockaday, "Facial and sublingual temperature changes following intravenous glucose injection in diabetics," Diabete & Metabolisme, 1982, 8, 15-19
[Non-Patent Document 2] A. R. Scott, T. Bennett, I. A. MacDonald, "Diabetes mellitus and thermoregulation," Can. J. Physiol. Pharmacol., 1987, 65, 1365-1376
[Patent Document 1] U.S. Pat. No. 5,924,996
[Patent Document 2] U.S. Pat. No. 5,795,305
[Patent Document 3] JP Patent Publication (Kokai) No. 2000-258343 A
[Patent Document 4] JP Patent Publication (Kokai) No. 10-33512 A (1998)
[Patent Document 5] JP Patent Publication (Kokai) No. 10-108857 A (1998)