The invention relates to a folding top for vehicles, which comprises a main bow which can pivot about a vehicle transverse axis. At each vehicle side a control arm is assigned to the respective two lateral struts of the top of the main bow serving as component parts of a top framework covered by means of a flexible roof skin. Roof skin retaining rails for tightening the roof skin are arranged on the outside of the struts of the top. These retaining rails are capable of being transferred by means of automatic adjustment mechanisms from a stretching position, spread apart from the struts of the top, which is the case when the main bow is upright and in which position the lower ends of the roof skin retaining rails rest against the side-boards of the associated structure, into a folding position nearer the struts during the course of the swing-back movement of the main bow. In order to avoid disturbing grinding noises during the course of the folding operation, as well as damage to visible side-board surfaces, it is provided that the adjustment mechanisms are arranged independently of the side-boards and are forcibly controlled by utilizing the relative movement between the struts of the top and the control arms taking place during the shifting of the main bow.

The invention relates to a folding top for vehicles of the type having a main bow which is pivotable about a vehicle transverse axis between top closed and open positions. Control arms are interconnected with respective lateral struts of the main bow. A pair of roof skin retaining rails are arranged laterally outside the respective lateral struts of the main bow and are movable between a top closed position where they hold the roof skin taut in position with their lower ends supported at vehicle side-boards and a top open position with the lower ends removed from the side-boards and inwardly of the struts to accommodate stowage.
Reference is made also to related, commonly assigned U.S. patent application Ser. No. 07/223,368, filed on even date herewith, and based on German Patent Application No. P 37 24 532.5, filed July 24, 1987 in Germany. This related application discloses other aspects of referenced embodiments of a convertible folding top.
Such a folding top is described in German Patent Specification No. 3,523,433. The width of entry of such a folding top during lowering into an assigned stowage compartment for the top is in this case clearly smaller than its maximum width when the top is closed, so that it can be accommodated without any problems in compartments for tops of motor cars having a tapered rear end, which are becoming increasingly widespread for aerodynamic reasons. At the same time, operating convenience is not impaired since the reduction in width during swinging back of the main bow takes place automatically. To control the roof skin retaining rails dependently on the swing-back angle of the main bow, a toggle lever is articulated between these rails and the assigned struts of the top on both sides in the proximity of the side-board upper edges, the toggle joint of which lever is supported on a compartment strut cover plate, arranged underneath the roof skin retaining rails, when the roof skin retaining bows are spread. This support absorbs the pretensioning forces of a return spring, which tends to pull the roof skin retaining rail into the swung-in folding position. Due to this toggle lever arrangement, during the shifting of the main bow from its upright position, a sliding process of the toggle joint or of the setting screw on the compartment strut cover plate on the toggle joint side inevitably occurs. This sliding process is accompanied by undesirable grinding noises, since it is necessary to refrain from lubricating the sliding surface for reasons of the risk that passengers in the vehicle may be soiled. Since, in addition, the head of the setting screw only rests at a point on the compartment strut cover plate during the sliding process, a relatively high contact pressure is produced. which may result in surface damage to the compartment strut cover plate.
A object of the invention is to further develop a folding top of the above-noted type in such a way that any occurrence of disturbing grinding noises during the course of the swinging in or out of the roof skin retaining rails and any occurrence of surface damage to visible side-board surfaces are reliably avoided.
This object is achieved according to the invention in that adjustment mechanisms for controlling movement of the roof skin retaining rails are arranged independently of the side-boards and are forcibly controlled by utilizing the relative movement between the lateral struts of the top main bow and the control arms taking place during the shifting of the main bow. This type of a mechanical forced control of the roof skin retaining rails is completely isolated physically and functionally from the vehicle side board edge structure.
According to certain preferred embodiments of the invention, it is provided that the adjustment mechanisms are actuated independently of the side-boards and that the lower ends of the roof skin retaining rails can move, in a first phase of the swing-back movement of the main bow, automatically into a position laterally and vertically spaced from the side-boards. In this embodiment, the adjustment mechanisms can be arranged directly at or over the board edges of the vehicle if they can be moved upwards away from the side-board edges together with the ends of the roof skin retaining rails. Otherwise, a sufficient vertical distance from the board edges must be maintained in this arrangement.
An important advantage of this alternative solution is, however, to be seen in that, beyond achieving the object of the invention, it is possible to use roof skin retaining rails on the folding top which overlap somewhat the outer contour of the side-boards near the board edges when the top is closed. With such a roof tile-like overlap, in which the roof skin fastened to the roof skin retaining rail around its lower end region is also involved, a reliable sealing of the connecting joint of the folding top to the structure is ensured more easily.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.


The invention relates to methods for controlling adaptive filters, where a first step involves a first input signal, which has a narrowband frequency range and occurs at least intermittently during an adaptation phase in the filter, at the input of the filter prompting the adaptation phase to be continued until an echo signal which is conditional upon the first input signal and in the same frequency range is compensated for completely, a second step involves the adaptation phase being suspended when complete compensation for the echo signal has been achieved, and a third step involves the adaptation phase being continued if the first input signal is followed by a second input signal which has a narrowband frequency range and which differs from the frequency range of the first input signal at least by a frequency value, with the above steps being repeated starting at the first step, or with a fourth step involving a new adaptation phase being performed if the first input signal is followed by a third input signal having a wideband frequency range. The invention also relates to an arrangement for carrying out the method.

1. Field of the Invention
The invention relates to a method for the adaptive filtering of signals as well as an arrangement for the adaptive filtering of signals.
2. Description of the Related Art
The use of adaptive filters is known in digital signal processing, that is, filters that are in a position to adapt their filter coefficients independently to the input signal.
The problem exists, particularly during the use of adaptive filters with so-called echo cancelers, which are used primarily in telecommunications and particularly during voice transmission over networks based on the Internet Protocol (IP)—the so-called Voice over IP (VoIP), that, if narrowband signals such as sinus tones occur during a phase in which the filter is adapted, it leads to erroneous adaptations.
An adaptive filter functions ideally, particularly if a white noise signal is present, since all frequencies occur simultaneously then, and all the information for calculating the coefficients of the adaptive filter is received from the echo path (transmission channel, telephone line). Information for the non-occurring frequencies is lacking with narrowband signals, which can lead to a drifting away of the coefficients.
What is known about this is that the adaptation phase is prolonged until a broadband signal is present once again, which ideally is equal to a white noise, representing an indication of the adaptation's reaching an optimal state.
In the meantime a drifting of the coefficients adapted to the echo, needed for the suppression of the echo thus cannot be prevented.
Furthermore, according to known solutions, the narrowband signals are detected by means of a comparison between the so-called crest factor (peak factor) of a received (voice) signal Rin, which describes the relationship between peak value and effective value of the voice signal, and the arithmetic mean value of the received (voice) signal Rin.
It is a disadvantage that the crest factor is not a clear sign of a narrowband signal, since broadband signals can also generate the same crest factor. In addition, narrowband signals that are not detectable via the crest factor can also occur.

Method and arrangement for controlling adaptive filters

Siemens Enterprise Communications GmbH & Co. KG


A circuit and method for reducing losses in a DC/DC converter by optimizing gate drive voltage. The circuit and method detect a change in the output load, or more specifically the output current, and adjust the gate voltage accordingly; in other words, providing adaptive gate drive voltage. In response to a reduction of output current, the invention reduces the gate voltage so as to reduce both conduction and switching losses in the semiconductor switching devices in the output stage.

1. Field of the Invention
The present invention relates to a DC/DC converter, and more particularly to a DC/DC converter including a circuit for driving the gates in the output stage adaptively as a function of output current.
2. Related Art
DC/DC converter designs today are supporting very high output currents of greater than 100 A. A key challenge at this power level is to reduce power loss to keep system efficiency as high as possible, given other system constraints such as board area, cost, etc. One technique that has been used to improve efficiency in these systems is to adjust the gate drive voltage to minimize the combination of switching loss and conduction loss in the converter.
A known DC/DC power output stage is shown schematically in FIG. 1. As seen, the output stage comprises a pair of power MOSFETs designated CTRL FET and SYNC FET connected in a totem-pole configuration with the source of CTRL FET and the drain of SYNC FET connected together at a node "A". The drain of CTRL FET is connected to a high voltage supply and the source of SYNC FET is grounded. The CTRL FET is driven with a voltage VGATE and a current IGATE and supplies an output current IOUT at a voltage VOUT. Filter elements LOUT and COUT are also shown.
In this circuit, the switching loss, the gate drive loss, and the conduction loss in CTRL FET are given by the following expressions:
                              Switching  loss                =                              V            GATE                    ·                      I            OUT                    ·                      F            SWX                    ·                                                    Q                GS                            +                              Q                GD                                                    I              GATE                                                          (        1        )                                          Gate  drive  loss                =                              V            GATE                    ·          Qg          ·                      F            SWX                                              (        2        )                                          Conduction  loss                =                              I            OUT            2                    ·                      R            DSON                                              (        3        )
wherein:
FSWX=switching frequency,
Qg=total charge,
QGS=gate-source charge,
QGD=gate-drain charge, and
RDSON is a function of VGATE.
Conduction losses can be reduced by increasing the gate drive voltage, albeit with diminishing returns.
FIG. 2 is a graph showing total power loss vs. gate drive voltage at 120 A load in a typical converter. As seen, the converter has an optimal gate drive voltage for this current level, where the total power loss reaches a minimum.
However, this known technique of tuning the gate drive voltage to minimize power loss only works well at one load current and is typically set at the maximum output load. In applications where the load current can drop to a very low percentage of full load current, the conduction power loss also decreases rapidly, but the switching power loss still burdens the converter, effectively reducing the overall system efficiency in this lighter load condition. Effectively, the optimal gate drive voltage level which minimizes power loss has changed due to the decreased load current.


The present invention relates to a closure and a container having the same, wherein the closure can be opened or closed through up/down operation to keep contents pressurized. A closure of the present invention comprises a sealing unit for surrounding a mouth of a container to ensure airtightness; a locking unit having a plurality of locking projections hingedly connected to a lower end of the sealing unit so that the locking projections can be caught by a locking flange-of the container; and a cover unit having a vertically movable annular body for surrounding an outer peripheral surface of the locking unit and including a push projection formed to protrude from an inner peripheral surface of the body and to be positioned below the locking unit, and a support projection formed to protrude at a position above the push projection to support the outer peripheral surface of the locking unit.

A container for storing beverages, powder or other contents is generally provided with a closure that requires to have a variety of functions depending on uses of the storing container or the stored contents.
For example, since the internal pressure of a carbonated beverage container should be maintained at a pressure equal to or greater than the atmospheric pressure, it is important to maintain the airtightness of the closure during distribution of the container.
In case of a container with large capacity, it is preferred that a closure be configured to be hermetically re-closed conveniently after opening the closure so that after the contents of the container are used, the remainder of the contents can be stored without being deteriorated. For example, a cork closure has excellent airtightness but has a problem in that it is not easy to open the cork closure.
Further, in case of a screw top that has been widely used in a conventional beverage container, it is inconvenient to use the screw top since the screw top should be rotated. Specifically, since children are too inexperienced in rotating the screw top to be opened/closed, it is very inconvenient for children to use the screw top.
Particularly, the screw top should be strongly fastened in order to prevent contents from leaking out. In this case, however, it is difficult to re-open the screw top. On the contrary, if the screw top is closed only to the extent that the screw top can be easily operated, the contents of the container may leak out.
In order to solve the above problems, the inventor proposed conveniently usable closure structures in Korean Patent No. 10-575259 (issued on Apr. 24, 2006) and Korean Utility Model Registration No. 20-385497 (issued on May 21, 2005). Since these closures are opened or closed in a one-touch manner, there is an advantage in that they can be more conveniently used as compared with a screw top.


An implantable cardiac stimulation system capable of automatic capture verification is provided with an associated method for performing automatic testing functions using programmable, or automatically determined, atrioventricular delays. Automatic threshold testing and evoked response sensitivity testing performed at a user-specified delay setting, rather than a preset setting, allows assessment of automatic capture verification based on an atrioventricular delay relevant to daily system function. Further features of the present invention are an adjustable frequency with which automatic threshold tests are performed and an adjustable frequency with which threshold test results are stored in memory in a threshold record for better monitoring of lead stability or impending clinical problems. The frequency of performing threshold tests and the frequency of storing threshold test results may be varied according to the threshold stability. Stored threshold test results are advantageously displayed with respect to a fixed or variable time scale.

In the normal human heart, the sinus node, generally located near the junction of the superior vena cava and the right atrium, constitutes the primary natural pacemaker initiating rhythmic electrical excitation of the heart chambers. The cardiac impulse arising from the sinus node is transmitted to the two atrial chambers, causing a depolarization known as a P-wave and the resulting atrial chamber contractions. The excitation pulse is further transmitted to and through the ventricles via the atrioventricular (A-V) node and a ventricular conduction system causing a depolarization known as an R-wave and the resulting ventricular chamber contractions.
Disruption of this natural pacing and conduction system as a result of aging or disease can be successfully treated by artificial cardiac pacing using implantable cardiac stimulation devices, including pacemakers and implantable defibrillators, which deliver rhythmic electrical pulses or anti-arrhythmia therapies to the heart at a desired energy and rate. A cardiac stimulation device is electrically coupled to the heart by one or more leads possessing one or more electrodes in contact with the heart muscle tissue (myocardium). One or more heart chambers may be electrically stimulated depending on the location and severity of the conduction disorder.
A stimulation pulse delivered to the myocardium must be of sufficient energy to depolarize the tissue, thereby causing a contraction, a condition commonly known as xe2x80x9ccapture.xe2x80x9d In early pacemakers, a fixed, high-energy pacing pulse was delivered to ensure capture. While this approach is straightforward, it quickly depletes battery energy and can result in patient discomfort due to extraneous stimulation of surrounding skeletal muscle tissue.
The capture xe2x80x9cthresholdxe2x80x9d is defined as the lowest stimulation pulse output (as may be reported in terms of pulse duration, pulse amplitude, pulse energy, pulse current or current density) at which consistent capture occurs. By stimulating the heart chambers at or just above threshold, comfortable and effective cardiac stimulation is provided without unnecessary depletion of battery energy. Threshold, however, varies significantly from patient to patient due to variations in electrode systems used, electrode positioning, physiological and anatomical variations of the heart itself, and so on. Furthermore, threshold will vary over time within a patient as, for example, fibrotic encapsulation of the electrode occurs during the first few weeks after surgery. Fluctuations may even occur over the course of a day or with changes in medical therapy or disease state.
Hence, techniques for monitoring the cardiac activity following delivery of a stimulation pulse have been incorporated in modern pacemakers in order to verify that capture has occurred. If a loss of capture is detected by such xe2x80x9ccapture-verificationxe2x80x9d algorithms, the pacemaker output is automatically increased until capture is restored. A threshold test is then performed by the cardiac stimulation device in order to re-determine the threshold and automatically adjust the stimulating pulse output. While a primary parameter to vary for adjusting the stimulation pulse output is the voltage, it should be clear that other parameters could be adjusted as well, including pulse duration, energy, charge, and/or current density.
This approach, referred to as xe2x80x9cautomatic capture,xe2x80x9d improves the cardiac stimulation device performance in at least four ways: 1) by verifying that the stimulation pulse delivered to the patient""s heart has been effective, 2) by maintaining the stimulation pulse output at the lowest level possible, thus 3) greatly increasing the device""s battery longevity by conserving the energy used to generate stimulation pulses, yet 4) always protecting the patient by providing a significantly higher output back-up pulse in the setting of loss of capture associated with the primary pulse.
One implemented technique for verifying capture automatically by an implantable stimulation device involves monitoring the intra-cardiac electrogram signal, also referred to as EGM or IEGM, received on the cardiac stimulation and sensing electrodes. When a stimulation pulse is delivered to the heart, the EGM signals that are manifest concurrent with depolarization of the myocardium are examined. When capture occurs, an xe2x80x9cevoked responsexe2x80x9d may be detected by special evoked response detection circuitry. The evoked response is the intracardiac atrial or ventricular depolarization that is observed as the P-wave or R-wave, respectively, on the surface ECG associated with a stimulus output. Detection of an evoked response indicates electrical activation of the respective cardiac tissue by the stimulating pulse. The depolarization of the heart tissue in response to the heart""s natural pacing function is referred to as an xe2x80x9cintrinsic response.xe2x80x9d
Through sampling and signal processing algorithms, the presence of an evoked response following a stimulation pulse is determined. A very short blanking period, or period of absolute refractoriness, following the stimulation pulse is applied to the evoked response sensing circuit immediately following the stimulation pulse to minimize or block out the stimulation pulse artifact.
This blanking period is followed by a special evoked response detection window, commonly 15 to 60 ms in duration, wherein the evoked response sensing circuit looks for an evoked response. For example, if a stimulation pulse is applied to the ventricle, an R-wave sensed by a special evoked response detection circuit of the pacemaker immediately following application of the ventricular stimulation pulse evidences capture of the ventricles.
If no evoked response is detected, a high-energy back-up stimulation pulse is delivered to the heart very shortly after the primary ineffective stimulus, typically within 60-100 ms of the primary pulse, in order to maintain the desired heart rate. If back-up stimulation pulses are required on two successive cycles, the system automatically begins to increase the stimulation output associated with the primary pulse until capture is restored, again for two consecutive cycles. Once capture is regained, an automatic threshold test is performed to re-determine the minimum pulse energy required to capture the heart at that time and adjust stimulation pulse output as needed.
An exemplary automatic threshold determination procedure is performed by progressively reducing the output from the functional output in 0.25 Volt steps until loss of capture occurs. With each loss of capture, a higher output back-up pulse is delivered in order to maintain the desired heart rate. Once loss of capture is achieved, the system increases the output in 0.125 Volt steps until stable capture is restored. Stable capture is defined as capture occurring on two consecutive primary pulses. Thus, reliable capture verification is of utmost importance in proper determination of the threshold.
Normally, capture threshold should be stable after the initial postoperative healing period. Frequent fluctuations in threshold can occur later, however, if a stimulating lead becomes dislodged, fractured, or its insulting sheath becomes discontinuous. Fluctuations in threshold may also reflect a change in clinical condition or the effects of a pharmacological agent. The automatic capture feature responds to such fluctuations by repeating a threshold test whenever the threshold rises enough to cause a loss of capture at the existing output setting. Threshold tests may also be repeated on a periodic basis to ascertain if a decrease in threshold has occurred. This automatic feature protects the patient by ensuring adequate stimulation pulse energy despite fluctuating threshold.
It is also desirable to store threshold test results on a frequent basis. Having a record of threshold changes over time will alert a medical practitioner to a possible lead failure or a change in the clinical condition of the patient, both of which warrant further medical evaluation. Such a feature is also referred to herein as xe2x80x9clong term threshold record.xe2x80x9d
Sensing an evoked response during threshold tests or capture verification, however, can be difficult for several reasons. One confounding factor in accurate capture detection is xe2x80x9cfusion.xe2x80x9d A fusion event occurs when a native depolarization and a stimulation pulse combine to contribute to the overall depolarization. The R-wave resulting from such a fusion event may be considerably diminished and not detectable by the normal R-wave detection scheme used for automatic capture verification. A fusion event may therefore easily be mistaken for a loss of capture.
Another somewhat related event that can confound accurate capture detection is xe2x80x9cpseudofusion.xe2x80x9d Pseudofusion occurs when a stimulation pulse is delivered simultaneously with an intrinsic depolarization but in this case does not contribute at all to the overall depolarization. The resulting Rwave, however, is distorted as observed on the EGM resulting in a loss of capture detection when in fact a native R-wave has occurred.
In each of the above cases, the result may be a loss of capture detection by the cardiac stimulation device when in fact a native depolarization prevented the algorithm from recognizing that there was a successful cardiac depolarization. The loss of capture detection will cause the stimulation device to deliver a high-energy back-up stimulation pulse and invoke the threshold testing function in a chamber of the heart even though these actions are not clinically necessary.
To overcome the problem of fusion, and to prevent the intrinsic heart rhythm from interfering with the process of stimulation and capture during threshold testing, the time-out interval after which a stimulation pulse is delivered is commonly shortened in order to ensure stimulation occurs before a native depolarization. During single chamber stimulation, the escape interval is shortened; during dual chamber stimulation, the AV and PV delays (the xe2x80x9catrioventricular delaysxe2x80x9d) are shortened. The AV delay is the interval following an atrial stimulation pulse that precedes delivery of a ventricular stimulation pulse. The PV delay is the interval following an atrial sensed P-wave preceding a ventricular stimulation pulse. By shortening the AV and PV delays, the ventricular pulse is delivered earlier than normally programmed following an atrial stimulation pulse or atrial sensed P-wave, respectively, and is expected to precede any natural depolarization of the ventricles. Reference is made to U.S. Pat. No. 5,411,533 to Dubreuil et al., U.S. Pat. No. 5,861,012 to Stroebel et al.
However, in some patients, a shortened AV or PV delay can cause deleterious hemodynamic effects, which may contribute to adverse symptoms or hypotension. Furthermore, in patients with first degree or even more severe atrial-ventricular conduction block, the shortened AV and PV delays are not required in order to perform a threshold test without encountering fusion. Thus, automatic obligatory shortening of the AV and PV delays to a non-physiologic interval may be unnecessary and undesirable.
Another signal that interferes with the detection of an evoked response, and potentially the most difficult for which to compensate because it is usually present in varying degrees, is lead polarization. A lead-tissue interface is that point at which an electrode of the pacemaker lead contacts the cardiac tissue. Lead polarization is commonly caused by electrochemical reactions that occur at the lead-tissue interface due to application of an electrical stimulation pulse across the interface. If the evoked response is sensed through the same lead electrodes through which the stimulation pulses are delivered, the resulting polarization signal, also referred to as an xe2x80x9cafterpotentialxe2x80x9d, formed at the electrode can corrupt the evoked response signal that is sensed by the sensing circuits. This undesirable situation occurs often because the polarization signal can be three or more orders of magnitude greater than the evoked response. Furthermore, the lead polarization signal is not easily characterized; it is a complex function of the lead materials, lead geometry, tissue impedance, stimulation energy and other variables.
Before enabling the automatic capture function of a cardiac stimulation device, an automatic capture calibration algorithm is performed which includes an evoked response sensitivity test. During an evoked response sensitivity test, the amplitude of the sensed evoked response and the amplitude of the lead polarization signal are measured. The test is performed by delivering stimulation pulse pairs at a high output setting, typically 4.5 Volts. This high output setting provides a xe2x80x9cworst casexe2x80x9d scenario in terms of the lead polarization signal. The first stimulation pulse will capture the myocardium producing an evoked response signal. The second stimulation pulse is delivered shortly after the first pulse when the myocardium is physiologically refractory and capture is impossible. The second pulse will therefore produce only a lead polarization signal without an evoked response. The evoked response amplitude measured after the first pulse is then compared to the polarization signal amplitude measured after the second pulse.
The difference between these signals must meet a minimum requirement so that the automatic capture verification can reliably distinguish between an evoked response and pure polarization in order to appropriately recognize capture and loss of capture. Based on the difference between the evoked response signal and the polarization signal, the cardiac stimulation system can automatically recommend whether automatic capture should be enabled and, if so, provide a recommended evoked response sensitivity setting.
Just as during threshold testing the evoked response sensitivity test is typically performed at shortened AV and PV delays so that an accurate measurement of the evoked response amplitude may be made without interference from native R-waves. While this situation eliminates the problem of fusion for measurement purposes, it may not reflect the normal day-to-day operating conditions of the stimulation device. Automatic capture verification will be enabled with settings that are valid at the tested AV and PV delays but may not be the optimal settings at the final programmed AV and PV delay settings.
It would thus be desirable to provide an implantable dual-chamber or multi-chamber cardiac stimulation device possessing automatic capture in which threshold testing and evoked response sensitivity measurements are performed in a way that avoids the possibility of an adverse hemodynamic response in an individual patient and further provides realistic results regarding the day-to-day performance of the device. Further, it would be desirable to provide a threshold record capable of documenting fluctuations in threshold that occur over brief periods of time so that a clinician may better monitor lead stability or identify changes in clinical condition.
The present invention addresses these needs by providing a system and method for performing automatic threshold testing and evoked response sensitivity testing using programmable AV and PV delays in an implantable dual chamber or multichamber cardiac stimulation device. A further feature of the present invention is a programmable or variable frequency with which automatic threshold tests are performed, and a programmable or variable frequency with which threshold test results are stored in memory. Stored threshold test results are advantageously displayed graphically with respect to a fixed or variable time scale.
The system and methods of the present invention avoid obligatory shortening of the AV and PV delay settings, which may have undesirable effects in some patients, during automatic threshold testing and evoked response sensitivity testing. Providing programmable AV and PV delay settings during evoked response sensitivity testing further allows the clinician to better assess the actual behavior of the cardiac stimulation device based on its daily function.
By measuring the evoked response amplitude under conditions similar to the operating conditions selected for daily operation, a more accurate evoked response sensitivity setting may be determined, minimizing the likelihood of false loss of capture detections precipitating back-up stimulation and threshold testing. By allowing threshold test measurements and data storage to be performed according to clinician-programmed frequencies or variable frequencies, the clinician can better monitor lead stability or impending clinical problems revealed through atypical fluctuations in capture threshold. Intervals of time in which frequent threshold fluctuations were recorded may be displayed on an expanding time scale to allow more careful inspection.
The present invention provides an implantable cardiac stimulation system including: an implantable stimulation device capable of delivering therapeutic or test stimulation pulses to one or both atrial chambers of the heart and one or both ventricular chambers of the heart and capable of acquiring cardiac data; a set of leads for receiving atrial and ventricular signals and for delivering atrial and ventricular stimulation pulses; and an external programmer capable of performing desired testing functions, displaying received data, and communicating with the implantable device via a telemetry circuit to send or receive programmed operating parameters or cardiac data.
A preferred embodiment of the implantable stimulation device includes a control system for controlling the operation of the device, a set of sensing circuits comprised of sense amplifiers for sensing and amplifying the atrial and ventricular signals, and pulse generators for generating the atrial and ventricular stimulation pulses. In addition, the implantable device includes memory for storing operational parameters for the control system, such as AV and PV delay intervals and threshold testing and recording intervals. The implantable device also includes a telemetry circuit for communication with the external programmer.
The external programmer preferably includes: a user interface, such as a keyboard, mouse or touch screen; a control system for controlling the operation of functions or tests carried out by the external programmer; a memory for storing control programs, operational parameters, or data received from the implantable device; and a display apparatus such an LCD screen or printer. The external programmer also includes a telemetry unit for transmitting data to and from the implanted device.
In a preferred embodiment, the implanted stimulation device performs an evoked response sensitivity test by controlling the delivery of stimulation pulses by the implanted device and making the appropriate signal measurements. A telemetry wand placed over the implanted device allows for transmission of operating parameters and receipt of cardiac signal data. Ventricular stimulation pulses of sufficient energy to ensure ventricular capture are delivered at programmed AV and PV delays. The AV and PV delays may be advantageously selected to be equal to the AV and PV delay settings that will be selected for the day-to-day function of the implanted device. Based on the results of the evoked response sensitivity test, at the desired AV and PV delay settings, the clinician can make appropriate decisions in enabling the automatic capture feature and in selecting the evoked response sensitivity setting.
With automatic capture enabled, threshold testing will be invoked whenever loss of capture, defined as loss of capture on two consecutive primary pulses, occurs. In the preferred embodiment, the AV and PV delay settings during threshold testing are programmable by the user. In this way, the AV and PV delay settings can be tailored to individual patient need rather than automatically shortened to a required test setting. In patients whom experience negative hemodynamic affects during short AV or PV delay stimulation (25 to 50 msec) and who are not likely to experience frequent fusion or pseudofusion events, the clinician can select a more physiologic delay setting (e.g., 100 msec). For patients in whom the programmed AV and PV delays will result in consistent ventricular fusion, the evoked response signal amplitudes can be measured in the real-life situation to allow for identification and programming of the appropriate evoked response sensitivity value.
In a preferred embodiment, periodic threshold testing is also performed at a frequency that is programmable by the clinician, such as every one hour, two hours, four hours, etc. The results of threshold tests, whether performed according to a periodic trigger or due to a loss of capture, can be stored in memory in what is referred to herein as a xe2x80x9clong term threshold record.xe2x80x9d The frequency by which threshold test results are written to memory is also preferably a programmable parameter. Furthermore, the frequency of threshold tests and/or the frequency of storing threshold test results may be automatically increased or decreased based on the instability or stability, respectively, of the measured threshold.
The implantable device is preferably capable of storing large amounts of data. Threshold data may be compressed as necessary to allow additional data to be stored. Stable threshold measurements may be overwritten by new data or compressed to a single data point with an appropriate time duration index. Preferably, abrupt changes in threshold, such as a change of more than 25% within 24 hours, are stored permanently in memory, with the corresponding date and time, until intentionally cleared from memory by a user. Stored threshold data may be downloaded to the external programmer at any time and displayed graphically for interpretation by a clinician. A variable, expanding time scale allows periods of fluctuating threshold to be examined more closely.
The system and method of the present invention thus improve the performance of dual chamber or multichamber cardiac stimulation systems possessing automatic capture by allowing greater flexibility in the operating parameters, specifically AV and PV delay, that control the threshold testing and evoked response sensitivity testing functions. AV and PV delay settings that are safe and appropriate for an individual patient may be selected by the user. Furthermore, evoked response sensitivity testing results will more accurately reflect the actual operating conditions of the implanted device. In addition, improved threshold measurement storage and display methods provided by the present invention provides the clinician valuable information in monitoring lead stability or other causes of threshold fluctuation.

System and method with improved automatic testing functions for automatic capture verification


A method for controlling a gateway device arranged between a client terminal and a server, and arranged to relay transmission and reception of e-mails, includes the steps of receiving a first e-mail stored in the server, converting the first e-mail into a second e-mail for temporary storage, transmitting the second e-mail to the client terminal, and managing information on the first e-mail and second e-mail.

1. Field of the Invention
The present invention relates to a gateway device arranged to relay transmission and reception of electronic mails (e-mails) and, in particular, relates to a processing technique for transmitting and receiving the e-mails by the gateway device.
2. Description of the Related Art
A gateway device that is arranged between a client and a server and that relays transmission and reception of e-mails is well known. Some gateway devices of this type include a function for encrypting/decrypting the e-mails.
The conventional gateway device includes a storage unit that stores the e-mails. In order to store a large number of e-mails, the storage unit preferably has a large capacity. However, as the capacity of the storage unit increases, a substantial storage with a large capacity is required, thereby affecting the production cost and management cost. Accordingly, a gateway device including a storage unit that shows good performance in spite of a small capacity and that requires only a small storage has been desired.

Gateway device, method for controlling the same, and program storage medium arranged to relay transmission and reception of E-mails


An improved method for fabricating a window frame/window piece assembly is disclosed in this application. A window frame having an opening in its inner portion is provided. According to one aspect, the window frame can be formed from a unitary piece of sheet metal. A transparent piece is attached to the inner portion of the window frame through a molding process. According to one embodiment, the window frame is placed within a mold such that the inner portion of the window frame projects into an inner cavity inside the mold. After the mold has been closed, a transparent material is injected into the inner cavity so that it bonds with the inner portion of the window frame. After the bond of between the transparent material and the window frame is set, the window frame/window piece assembly is removed from the mold. According to another embodiment, a plurality of window frames may be loaded into a single mold so that a plurality of window frame/window piece assemblies can be fabricated in a single batch.

Micromechanical devices are small structures typically fabricated on a semiconductor wafer using techniques such as optical lithography, doping, metal sputtering, oxide deposition, and plasma etching similar to those developed for the fabrication of integrated circuits. Digital micromirror devices (DMDs), sometimes referred to as deformable micromirror devices, are a type of micromechanical device. Other types of micromechanical devices include accelerometers, pressure and flow sensors, gears and motors.
Digital micromirror devices have been utilized in optical display systems. In these display systems, the DMD is a light modulator that uses digital image data to modulate a beam of light by selectively reflecting portions of the beam of light to a display screen. While analog modes of operation are possible, DMDs typically operate in a digital bistable mode of operation and as such are the core of many digital full-color image projection systems.
Micromirrors have evolved rapidly over the past ten to fifteen years. Early devices used a deformable reflective membrane that, when electrostatically attracted to an underlying address electrode, dimpled toward the address electrode. Schieren optics illuminate the membrane and create an image from the light scattered by the dimpled portions of the membrane. Schlieren systems enabled the membrane devices to form images, but the images formed were very dim and had low contrast ratios, making them unsuitable for most image display applications.
Later micromirror devices used flaps or diving board-shaped cantilever beams of silicon or aluminum, coupled with dark-field optics to create images having improved contrast ratios. Flap and cantilever beam devices typically used a single metal layer to form the top reflective layer of the device. This single metal layer tended to deform over a large region, however, which scattered light impinging on the deformed portion. Thin hinge structures, which restrict the deformation to a relatively small region of the device, limit the amount of light scattered and improve image quality.
Torsion beam devices enabled the use of dark field optical systems. Torsion beam devices use a thin metal layer to form a torsion beam, which is referred to as a hinge, and a thicker metal layer to form a rigid member, or beam, typically having a mirror-like surface. The rigid member or mirror is suspended by, and typically centered on, the torsion hinge—allowing the mirror to rotate by twisting the torsion hinge. Address electrodes are formed on the substrate beneath the mirror on either side of the torsion hinge axis. Electrostatic attraction between an address electrode and the mirror, which in effect form the two plates of an air gap capacitor, is used to rotate the mirror about the longitudinal axis of the hinge.
Recent micromirror configurations, called hidden-hinge designs, further improve the image contrast ratio by using an elevated mirror to block most of the light from reaching the torsion beam hinges. The elevated mirror is connected to an underlying torsion beam or yoke by a support post. The yoke is attached to the torsion hinges, which in turn are connected to rigid support posts. Because the structures that support the mirror and allow it to rotate are underneath the mirror instead of around the perimeter of the mirror, virtually the entire surface of the device is used to fabricate the mirror. Since virtually all of the light incident on a hidden-hinge micromirror device reaches an active mirror surface—and is thus either used to form an image pixel or is reflected away from the image to a light trap—the hidden-hinge device's contrast ratio is much higher than the contrast ratio of previous devices.
Images are created by positioning the DMD so that a light beam strikes the DMD at an angle equal to twice the angle of rotation. In this position, the mirrors fully rotated toward the light source reflect light in a direction normal to the surface of the micromirror device and into the aperture of a projection lens—transmitting light to a pixel on the image plane. Mirrors rotated away from the light source reflect light away from the projection lens—leaving the corresponding pixel dark.
Full-color images are generated either by using three micromirror devices to produce three single-color images, or by sequentially forming three single-color images using a single micromirror device illuminated by a beam of light passing through three color filters mounted on a rotating color wheel.
An example of a small portion of a digital micromirror array is depicted in FIG. 1. In FIG. 1, a small portion of a digital micromirror array 100 with several mirrors 102 is depicted. Some of the mirrors 102 have been removed to show the underlying structure of the DMD array. FIG. 2 is an exploded close-up of one individual mirror 102 of a DMD array. The electrical interconnections and operations of the individual micromirrors 102 are described in further detail in U.S. Pat. No. 6,323,982 entitled Yield Superstructure for Digital Micromirror Device to Larry J. Hornbeck, which is hereby incorporated by reference.
A representative example of an existing spatial light modulator (SLM) device 300 is depicted in FIG. 3. In FIG. 3, a micromirror array 100 is mounted onto a ceramic base 305, which is further mounted onto a printed circuit board (PCB) or electronic lead package 310. The micromirror array 100 is electrically connected to the ceramic base 305 by a series of leads 315. Each of the leads 315 is connected to the micromirror array 100 at bonding pads 320 that are integral to the micromirror array 100. At the other end, the leads 315 are connected to bonding pads 325, which are integral to the ceramic base 305. Each of the bonding pads 325 on the ceramic base 305 is connected to a series of land grid array (LGA) pads on the bottom of the ceramic base 305 through internal interconnect layers that are built into the ceramic base. The LGA-type pads may then be connected to the PCB 310 via elastomer or C-spring connectors. In order to ensure a reliable electrical connection between the ceramic base 305 and the PCB 310, a mechanical loading must be applied between the ceramic base 305 and the PCB 310. FIG. 3 describes only one representative embodiment for electrically connecting the micromirror array 100. Other suitable arrangements for electrically connecting the micromirror array 100 are well known in the art.
The micromirror array 100 depicted in FIG. 3 is hermetically sealed in the SLM device 300 to prevent the array 100 from becoming damaged. To accomplish this, a seal ring 335 is disposed on the ceramic base 305 so that the micromirror array 100 is surrounded. A window frame 340, which incorporates an optically transparent piece 345, is mounted onto the seal ring 335 to form a seal that encases the micromirror array 100. The window frame 340 comprises a single block of metal or other suitable material that has been formed through forging or CNC machining. The transparent piece 345 is typically a piece of glass or other optically transmissive material that is mounted and sealed into the window frame 340. The window frame 340 is mounted onto the seal ring 335 by seam welding or other suitable processes that forms a seal between the seal ring 335 and the frame 340.
A cross-sectional view of the SLM device 300 depicted in FIG. 3 along the axis 4-4 is depicted in FIG. 4. Many of the same components described above (the micromirror array 100, the ceramic base 305, the electronic lead package 310, the electronic leads 315, bonding pads 320 and 325, the seal ring 335, the window frame 340, and the transparent piece 345) are depicted in FIG. 4. Also depicted is a heat sink 400 that is mounted onto the bottom of the base 305. The heat sink 400 absorbs the heat generated by the micromirror array 100 when it is illuminated with a light source during its operation. Further details of the components and connections of a typical SLM device are described in U.S. Pat. No. 5,936,758 entitled Method of Passivating a Micromechanical Device Within a Hermetic Package to Edward C. Fisher, et al., which is hereby incorporated by reference.
A problem associated with existing SLM devices 300 arises from the fact that the costs associated with manufacturing the window frame 340 and the transparent piece 345 can be high. This is a result of several factors. At the outset, it should be noted that existing designs for the window frame 340 require a relatively large amount of metal to form the shapes that are depicted in FIGS. 3 and 4. This can add substantial materials costs to the total cost of a SLM device 300. Furthermore, the process of forming the window frame 340 requires CNC machining or forging, which are relatively expensive processes. In addition, because the transparent piece 345 is mounted into the window frame 340 by a fusing process, the transparent piece 345 must be polished after it is mounted in the window frame 340. Moreover, anti-reflective coatings and chrome coatings cannot be applied to the transparent piece before it is mounted to the window frame 340. This means that each of the window frame/transparent piece assemblies must be individually polished and coated with the appropriate layers after the frame mounting process. There is therefore a need in the art for an improved window frame/transparent piece assembly that utilizes fewer raw materials, is less expensive to fabricate, and can be processed in batches so that certain processes, such as materials coatings, can be applied to more than one window frame/transparent piece assembly at a time.

Method and apparatus for forming a DMD window frame with molded glass


A method of storing a file in a memory. An explicit command is issued to a file system to store the file in accordance with a desired performance characteristic of the file such as enhanced write performance, enhanced read performance or enhanced latency performance. The file system stores the file in the memory in accordance with the desired performance characteristic. Preferably the desired performance characteristic is achieved by storing the file in a physically contiguous portion of the memory or in a logically contiguous portion of the memory. After the explicit command has been issued for each of a plurality of files, the files may be stored concurrently.

The present invention relates to file systems and, more particularly, to a file system that supports an explicit command to store files in accordance with desired performance characteristics of the files.
Almost all computer systems, whether large mainframes or tiny embedded micro controllers, need to store data such that the data shall not be lost when the system is powered down. Therefore those computers usually include some kind of Non Volatile Memory (NVM), in addition to any volatile memory they may use for running their programs. The NVM may be a magnetic disk, a flash memory chip, or any other non-volatile storage element.
FIG. 1 shows the general structure of how such a storage device is accessed. At the bottom of the Figure is a physical storage medium 10, which is the hardware layer implementing the physical storage. As each storage device may have its own unique interface and peculiarities which make it very inconvenient to work with, it is the common practice to have a software device driver 12 included in the operating system running on the computer (or running on the bare hardware, if no operating system is used), with this device driver 12 providing a simplified and standardized interface for other software components wishing to access the device. For storage devices 10 used for storing files (i.e. disks, diskettes, etc.), but not only for them, the interface provided by their device drivers 12 is usually of the type known as a "block device driver". Such device drivers 12 interact with their clients using blocks of data rather than single bytes. This applies to both input and output operations, that is, to both reading and writing. The most common example of a block device 10 is the magnetic disk, whose hardware interface is commonly configured for transferring only complete blocks (usually called "sectors" in this context), such as 512 bytes or more. It should be emphasized that it is not necessary for physical storage device 10 to be physically limited to block operations in order to have a device driver 12 presenting a block device interface. For example, a battery-backed RAM disk is not physically limited to blocks and may physically read and write each of its memory bytes. Still, typically its device driver 12 presents a block device interface to the rest of the system, so as to be compatible and interchangeable with magnetic disks. Therefore, for the purpose of the present invention, a block device is any device whose driver 12 presents a block device interface, regardless of its actual physical structure.
A block device seems to its users as a linear array of blocks of a certain fixed size. Each one of these blocks can be read or written independently of the other blocks using its index in the array, as shown in FIG. 2. The common practice (which is also used here) is to number the blocks starting from block number 0 (21), and ending in block number (N−1) 22, where N is the number of blocks exported by the device driver. Again it should be emphasized that this linear array structure does not necessarily exist at the physical device level. For example, a flash disk block device driver 12 also presents this linear array image, but internally the physical blocks on flash medium 10 are usually scattered in a random order (such that block number 0 may physically be located in the middle or the end of flash medium 10) due to the writing limitations in flash memory and the possible existence of bad blocks. It should also be understood that block device driver 12 has no knowledge of the contents put into its blocks by the upper software layers 14 and 16.
Referring again to FIG. 1, it is seen that there is usually a File System (FS) software layer 14 on top of device driver 12. A FS 14 is a software component which provides further insulation from physical device 10, by enabling the application programs 16 to interact with storage device 10 using only the concept of files, a concept which is much more natural and convenient to the typical programmer or user. FS 14 achieves this abstraction by organizing the user data on block device 10 into some logical structure, and associating the blocks containing a file's data with the file's attributes (i.e. file name, creation time, access permissions, etc.). For that purpose FS 14 stores into device 10 meta-data, which are not directly visible to the user, and which include the FS 14 internal book-keeping information with which FS 14 is able to trace and access the user files. For example, the Microsoft DOS FAT12 file system, which is one of the simplest FS commercially available, stores on storage device 10 a boot sector containing some basic parameters, allowing the location of the other meta-data structures (which must be in the first block of device 10), one or more copies of the File Allocation Table (FAT), which is the allocation map of device 10, and a root directory structure for locating files by name. Application programs 16 interact with FS 14 on the file-level, by issuing commands such as "open file", "delete file", "write file", etc. Application programs 16 thus are completely ignorant of the underlying block structure. There are many file systems 14 in use today, greatly differing in their internal structures and characteristics. In many cases (such as with the Linux operating system) an operating system even provides several file systems 14 to its users and they may choose the one most suitable for their needs.
While most prior art storage systems follow the layered modular separation between device driver 12 and file system 14 that is illustrated in FIG. 1, there are storage systems in which such clear separation does not exist and in which both device driver and file system functionalities are combined into one software module. Such systems are typically referred to as "monolithic" storage systems. It should be understood that while all explanations are given here using the layered model, the present invention is equally applicable to the monolithic model, where any reference to a "file system" should be interpreted as referring to the file-handling portion of the monolithic software, and any reference to a "device driver" should be interpreted as referring to the device-handling portion of the monolithic software.
More details of the considerations related to the handling of files by a file system are found in Mosek, US Patent Application Publication No. 2005/0193025, filed on May 20, 2004 and entitled "A File System that Manages Files According to Content". This patent application is incorporated by reference for all purposes as if fully set forth herein.
Prior art file systems 14 and storage device drivers 12 handle storage space allocation the same for all files. One must understand, though, that the way a file is allocated physical space may affect the performance the user will see when accessing the file.
As an example consider the case of reading a file that spans many sectors (a sector is the minimal chunk of data read or written to/from medium 10. A sector is typically 512 bytes long). Let us assume that storage medium 10 which is used by file system 14 is a solid-state flash disk. Assume that file system 14 is called upon to read the first 16 KB of the file. This translates to reading the first 32 data sectors. Even though the user logically views those 16 KB as if they are residing on medium 10 as a continuous stream of data, this is not necessarily the way the data are physically stored on medium 10. File systems 14 typically allocate medium space when there is a need for writing new data, and their allocation policy can be non-sequential. A simple example for this is the very widely used Microsoft FAT file system, the one used in DOS and many Windows operating systems. FAT allocates space in "clusters", with each cluster containing a few sectors (a typical case is 4 sectors per cluster). Even though the sectors within the same cluster will be allocated physically sequential locations on medium 10, there is no necessity that logically adjacent clusters (that is—clusters having adjacent logical addresses) will be physically close to each other on medium 10. File system 14 may decide to allocate clusters that were left free in the middle of the space used by another file, thus mapping a continuous range of logically sequential data into a few physically non-sequential chunks of medium 10. (Microsoft does provide a utility for "defragmenting" a disk drive. Such a utility re-arranges the files on the medium so that the files are "continuous". However, the defragmenting utility is very time-consuming and is typically run by the system's user only once in a few weeks, while in the in-between period the disk gradually returns to its "non-continuous" state. Additionally, one should distinguish between logically continuous storage and physically continuous or contiguous storage. For flash disks these are not the same. Due to flash limitations of bad blocks and the inability to rewrite without erasing big chunks of space, flash memory management systems employ mapping of logical addresses to physical addresses, so that even though the device driver reports continuous allocation, physically it is not so). More details of the way FAT-like file systems handle storage allocation are found in Ban et al., US Patent Application Publication No. 2004/0193564, filed on Mar. 27, 2003 and entitled "Robust Self-Maintaining File System". This patent application is incorporated by reference for all purposes as if fully set forth herein.
Many NAND-type flash memory devices (typically used for implementing solid-state disks or memory cards) have a feature of "continuous reading". This means that when the last byte of a flash page (the equivalent of a data sector on the device hardware level) is read out of the device, the device automatically starts loading its internal data buffer from the memory cells of the physically next page. In NAND flash, the time required for loading the data buffer with the stored data is relatively long and has a major effect on the reading performance of the memory system. A typical value for the time it takes to load the buffer is 15 microseconds. For a 16-bit wide device using 100 nanosecond bus cycles, the time required for transferring a 512-byte page over the bus is 256×0.1=25.6 microseconds, which is of the same order of magnitude as the buffer loading time. Therefore doing buffer loading in advance can significantly speed-up the reading of a sector, and consequently the reading of the file. However, such saving of time using the "continuous reading" feature is only possible when the next page to be read is physically sequential to the previously read page. It follows that reading performance is affected by the storage allocation policy and can benefit from "clever" allocation decisions.
Based on the above, it can be seen that it is advantageous to have files physically continuous on medium 10, so why not allocate all files like that? The reason is that even in a moderately-complex system file system 14 has to support hundreds of files residing in parallel within medium 10. Those files are created, written to, appended to, deleted, or otherwise changed in many complex and unpredictable sequences of events. Keeping all files physically sequential is simply impossible except in the most simple systems. For example, a user adding a few lines to an existing text file forces file system 14 to extend the file length. But if the space immediately following the file is currently used by another file, the only options available are to break the updated file to non-sequential parts, to move the entire other file to another location and use its old space for the updated file, or to move the entire updated file to another location where there is enough room. In almost all cases the preferred decision is to break continuity, as the other options are much more costly in time.
As another example, consider the case of writing a file into a flash disk. Flash memory devices have the characteristic that a page cannot be written into unless the block targeted for the write was previously erased. This implies that while the disk is being continuously used it is necessary to recycle (erase) blocks of the disk so as to make room for new data. Such recycling may be done only when there is an immediate need for free space, or it also may be done periodically or when the system has idle time. For better understanding the issues of flash memory allocation and recycling see Ban, U.S. Pat. No. 5,404,485, entitled "Flash File System", that issued on Apr. 4, 1995. This patent is incorporated by reference for all purposes as if fully set forth herein.
The time it takes a storage system to write a file depends on whether there is free space immediately available for allocation or whether some space first should be recycled in order to generate usable space. Erasing flash blocks is a rather slow operation (a few milliseconds in NAND flash and a few hundred milliseconds in NOR flash), so this might have a major impact on a file's write performance. If it could be guaranteed that the storage required for writing a file is somehow reserved for it in advance so that no recycling will be required, its write performance will be guaranteed to be higher.
Indeed, the idea of reserving flash space in advance of writing is not new—Intel Corporation provides a flash management software package called Flash Data Integrator (or "FDI" for short) that allows its user to "initialize" a "packet" of storage and then fill up the packet with data. The initialization includes the pre-allocation of free space, causing recycling if necessary. However, the FDI use of this idea is rather primitive and limited—it does not apply at all to files but to some type of objects which are primitive structures identified by a numeric identifier. Also, only one packet stream can be open for input at a time.
So prior art storage systems that treat all files the same in terms of space allocation, do not allow a user to obtain optimal performance for a specific file.
There is thus a widely recognized need for, and it would be highly advantageous to have, a file system 14 that allows an application program 16 to request special ad hoc storage of a file on a medium 10, for optimal performance
It should be clarified here that the term "performance" as employed herein, refers not only to write performance or read performance, as might be suggested by the examples listed above. Performance should also be interpreted to include any other characteristics associated with the execution of storage system operations related to time. For example, the latency of a storage system is also a performance characteristic. By latency is meant the amount of time it takes the storage system to complete a single call. In some so-called "hard" real-time systems, it is a mandatory requirement that no single call should exceed a given duration, so that no delay will be incurred in performing some time-critical operation. So in such systems low latency is a required performance characteristic.
Also, it should be clarified that even though in all the examples presented herein media 10 are solid-state flash disks, the present invention is equally applicable to other types of storage media, including magnetic disks. Even though the considerations for what constitutes optimal allocation for a file generally are different for different media types, the same ideas still apply. For example, in magnetic disks there is the issue of optimizing the mechanical movements of the read/write heads used for accessing the storage area, with different considerations applying to reading and writing. Therefore the present invention as described and claimed below is also applicable to this case too.

Method of managing files for optimal performance


A method for treating cerebral vascular diseases in a human or non-human animal is disclosed. The method involves inhibiting 20-HETE synthesizing enzyme activity sufficiently to increase or prevent a decrease in cerebral blood flow in the human or non-human animal.

Reduced cerebral blood flow can cause a range of problems from light headaches to severe brain damage and death. There are many situations that can lead to reduced cerebral blood flow. Examples of such situations include hemorrhagic stroke, brain injuries, occlusive stroke, cerebral vasospasm and hypotension.
Subarachnoid hemorrhage (SAH) accounts for 5-10% of all strokes. The incidence is 2-20 events per 100,000 population per year with a case fatality rate of 20-60%. Ingall, T et al., Stroke 31: 1054-1061 (2000); Stroke 31: 1843-1850 (2000). SAH occurs most commonly after rupture of cerebral aneurysms or head trauma leading to subarachnoid bleeding and clot formation. After the bleeding, cerebral blood flow initially falls due to an elevated cerebrospinal fluid pressure that reduces effective perfusion pressure combined with the release of vasoactive agents from the blood that increases cerebral vascular tone. This initial phase of injury following SAH is associated with a high mortality (30-50%). Later cerebrovasospasm (CVS) develops with a delayed onset (2-3 days in rats, 5-7 days in human beings). The mortality associated with this delayed CVS is even more devastating and approaches 70%. Weir, B., Br. J. Neurosurg 9: 375-390 (1995). Very little is known about the factors that are released by blood and reduce cerebral blood flow in the initial phase after SAH. Even less is known about what mediates delayed CVS. Previous studies have indicated that the delayed CVS following SAH is associated with activation of protein kinase C (PKC), diminished activity of K+ channels and depolarization of vascular smooth muscle (VSM) cells. Depolarization of cerebral VSM cells increases influx of calcium which potentiates the vasoconstrictor response to endothelin (ET), thromboxane, serotonin and other vasoconstrictors produced by clotting blood and diminishes the responsiveness of cerebral vessels to endogenously formed vasodilators such as nitric oxide (NO). The impaired response to NO has been postulated to be due to the binding of NO to free hemoglobin after hemolysis of erythrocytes, Edwards, D. H. et al., J. Neurosurg. 76: 830-837 (1992), or increased degradation of NO by superoxide formed by oxidation of hemoglobin. Misra, H. P. et al., J. Biol. Chem. 247: 6960-6962 (1972); Winterbourn C C et al., Biochem. J. 155: 493-502 (1976). Moreover, there is evidence that the activity of one of the second messengers of NO, soluble guanylyl cyclase, is reduced following SAH. Faraci, F. M. and Sobey, G. C., Brain Res. 821: 368-373 (1999); Sehba, F. A. et al., Stroke 30: 1955-1961 (1999).
Other studies have explored the role of upregulation of vasoconstrictor pathways in mediating CVS following SAH. ET levels increase after SAH. The initial fall in cerebral blood flow observed two hours after induction of SAH in rats is attenuated by inhibitors of the synthesis of ET and by ET receptor blockers. Clozel, M. and Watanabe, H., Life Sci. 52: 825-834 (1993). Enhanced fatty acid turnover and increased formation of vasoconstrictor metabolites of arachidonic acid (AA) have also been observed following SAH. Juvela S, J. Neurosurg. 92: 390-400 (2000); Seifert, V. et al., J. Neurosurg. 82: 55-62 (1995). Recent studies have indicated that 20-hydroxyeicosetetraenoic acid (20-HETE) is a metabolite of AA produced in the cerebral circulation. However, the role of 20-HETE in the pathogenesis of CVS following SAH is unknown. 20-HETE is produced by enzymes of the cytochrome P450 (CYP) 4A family that are expressed in VSM cells in cerebral arteries. Harder, D. R. et al., Am J Physiol Heart Circ Physiol. 266: H2098-H2107 (1994); Gebremendin, D. et al., Circ Res. 87: 60-65, 2000. The CYP4A family members for 20-HETE formation include CYP4A1, 2, 3 and 8 in rats, CYP4A10, 12 and 14 in mice, and CYP4A11 in human. Enzymes of the CYP4F family are also involved in 20-HETE production. The CYP4F family members for 20-HETE formation include CYP4F1, 4, 5 and 6 in rats, and CYP4F2 and 3 in human. CYP4F2 has been shown to produce 20-HETE when incubated with AA. Powell, P. K. et al., J Pharmacol Exp Therap 285: 1327-1336, 1998. CYP4F3 has been shown to be expressed in polymorphonuclear white blood cells that produce 20-HETE. Bednar, M. M. et al., Biochem Pharmacol 60: 447-455, 2000; Rosolowsky, M. et al., Biochem Biophys Acta 1300: 143-150, 1996.
20-HETE is a potent constrictor of cerebral arteries (EC50<10 nM). 20-HETE activates PKC and depolarizes VSM cells by inhibiting the large conductance KCa channel. 20-HETE also increases Ca2+ influx via L-type Ca2+ channels in the cerebral vasculature, Harder, D. R. et al., Am J Physiol Heart Circ Physiol. 266: H2098-H2107 (1994); Gebremedhin, D. et al., J. Physiol (Lond). 507 (Pt 3): 771-781 (1998), and plays a critical role in the mechanism underlying the autoregulation of cerebral blood flow in rats. Alonso-Galicia, M. et al., Stroke 30: 2727-2734 (1999); Gebremedhin, D. et al., Circ. Res. 87: 60-65 (2000). Vasoconstrictor peptides like angiotensin II and ET stimulate the formation of 20-HETE. Oyekan, A. et al., Am J Physiol Regulatory Integrative Comp Physiol. 273: R293-R300 (1997); Croft, K. D. et al., Am. J. Physiol Renal Physiol. 279: F544-F551 (2000). The vasodilator NO inhibits the formation of 20-HETE. Alonso-Galicia, M. et al., Stroke 30: 2727-2734 (1999). Activated polymorphonuclear leukocytes (PMN) and cerebral arteries avidly produce 20-HETE. Harder, D. R. et al., Am J Physiol Heart Circ Physiol. 266: H2098-H2107 (1994); Gebremedhin, D. et al., J. Physiol (Lond). 507 (Pt 3): 771-781 (1998); Alonso-Galicia M. et al., Stroke 30: 2727-2734 (1999); Gebremedhin, D. et al., Circ. Res. 87: 60-65 (2000); Bednar, M. M. et al., Biochem. Pharmacol. 60: 447-455 (2000); Rosolowsky, M. et al., Biochem Biophys Acta 1300: 143-150, 1996; Lange, A. et al., J. Biol. Chem. 272: 27345-27352 (1997). However, it is not known whether treating an animal with a 20-HETE synthesizing enzyme inhibitor will prevent the initial fall in cerebral blood flow associated with SAH (hemorrhagic stroke) or the delayed CVS and cerebral ischemia. Moreover, drugs that are currently available for inhibiting the formation of 20-HETE have serious limitations that greatly restrict their potential as therapeutic agents. For example, although 17-ODYA inhibits the synthesis of 20-HETE, it is not a specific inhibitor because it is equally effective at blocking the formation of EETs. Zou, A. P. et al., J Pharmacol Exp Therap 268: 474-481, 1994. EETs are potent vasodilators formed in the brain. Blockade of the synthesis of EETs may oppose any beneficial effects associated with blockade of the formation of 20-HETE. Alkayed, N. J. et al., Am J Physiol Heart Circ Physiol 271: H1541-H1546, 1996; Gebremendhin, D. et al., Am J Physiol Heart Circ Physiol 263: H519-H525, 1992. 17-Octadecynoic acid (17-ODYA) also binds to plasma proteins and does not cross the blood brain barrier when given systemically. DDMS is a more specific inhibitor of the formation of 20-HETE. Alonso-Galicia, M. et al., Hypertension 29:320-325, 1997; Wang, M. H. et al., J Pharin Exp Therap 284:966-973, 1998. However, it too binds to plasma proteins and does not cross the blood-brain barrier when given systemically.
The effects of intracerebroventricular injection of DDMS on cerebral blood flow has been examined in previous studies. DDMS has no effect on baseline cerebral blood flow. However, it blocks autoregulation of cerebral blood flow, i.e., constriction of cerebral vessels associated with elevations in cerebral blood flow. Gebremendin, D. et al., Circ Res. 87:60-65, 2000. DDMS has also been reported to prevent the rise in cerebral blood flow produced by the NO donor, DEA NONOate. Alonso-Galicia, M. et al., Stroke 30:2727-2734, 1999. However, there is no in vivo information available as to whether DDMS or 17-ODYA have beneficial effects in preventing or reversing a fall in cerebral blood flow such as that associated with SAH or stroke and other cerebral vascular diseases.

Use of 20-HETE synthesizing enzyme inhibitors as therapy for cerebral vascular disease


A frequency hopping, spread spectrum transceiver for wireless data telemetry directly modulates data for transmission using minimum shift keying (MSK) modulation; the transceiver includes a transmit Voltage Controlled Oscillator (VCO) to provide an input to a modulator. A programmable attenuator circuit is used between the source of transmit data, the micro processing unit (MPU), and the transmit phase locked loop (PLL) summing junction. The programmable attenuator provides a selectively attenuated data signal that is coupled to the PLL summing junction to generate a modulated data signal for transmission and dynamically adjusts the transmit data stream voltage level as required to achieve a fixed level in frequency deviation based on the present VCO operating frequency. A complete set of VCO characterization measurements is obtained beforehand. The VCO characterization measurements are stored in memory and the MPU controls the attenuation circuit to provide the exact Transmit Data signal level required for optimum modulation depth.

1. Field of the Invention
The present invention relates to wireless data telemetry system utilizing spread spectrum frequency hopping transceivers, and, more particularly, to circuits and methods for selectively controlling modulation depth when transmitting data.
2. Discussion of the Prior Art
Wireless data telemetry methods have been well documented; infrared and radio frequency (RF) are the principal wireless communication technologies described in the prior art. Infrared beam communications systems cannot operate over distances of more than a few feet and so are limited to applications such as bar code scanning, local computing devices, and television (or other home appliance) remote control.
Accordingly, most wireless data transmission products in the prior art utilize standard RF technology, i.e., radios, the same technology used in vehicle dispatch and police communication systems. Standard RF products are relatively simple and inexpensive to build but require FCC licenses to operate. RF transmissions are susceptible to interference from a growing number of sources and to interception by readily available eavesdropping equipment. The unreliable quality of standard RF transmissions makes the technology unsuitable for applications where all of the information transmitted must be accurate, complete, and secure.
In order to overcome the shortcomings of standard RF transmission, direct sequence spread spectrum (DSSS) was developed. DSSS radios divide or slice transmissions into small bits thereby spreading energy from the bits simultaneously across a wide range or spectrum of radio frequencies. DSSS is a relatively unreliable transmission medium, however, because spreading the message across a wide spectrum greatly reduces the strength of the radio signal carrying the message weakening the signal. A DSSS receiver must simultaneously monitor the entire allotted spectrum, thereby risking severe interference from any high energy RF source appearing within the monitored spectrum. DSSS performance also degrades quickly in shared-service environments having multiple radio systems operating simultaneously.
Frequency hopping spread spectrum (FHSS) technology was developed by the U.S. military to prevent interference with or interception of radio transmissions on the battle field and is employed by the military in situations where reliability and the coexistence of multiple radio systems are critical. Standard RF and DSSS cannot match the reliability and security provided by frequency hopping. Instead of spreading (and therefore diluting) the signal carrying each bit across an allotted spectrum, as in DSSS, frequency hopping radios concentrate full power into a very narrow spectral width and randomly hop from one frequency to another in a sequence within a defined band, up to several thousand times per second. Each FHSS transmitter and receiver coordinate their hopping sequence to ensure a reliable exchange of data. Upon encountering interference on a particular frequency, the transmitter and receiver retain the affected data, hop to another point in the spectrum and then continue the transmission. Statistically, there are always spaces without interference somewhere in the spectrum, since benign producers of interference or a hostile jammer cannot easily jam all possible frequencies simultaneously and at high power radiation levels.
The frequency hopping transmitter and receiver find frequencies with no interference and complete the transmission. This ability to avoid interference enables FHSS radios to perform more reliably over longer ranges than standard fixed channel RF or DSSS radios. In the past, frequency hopping communication systems have been used almost exclusively in extremely expensive robust military or government communication systems.
Generally speaking, data telemetry is the transmission of short packets of information from equipment or sensors to a recorder or central control unit. The data packets are transferred as electric signals via wire, infrared or RF technologies and data is received at a central control unit such as a computer with software for automatically polling and controlling the remote devices. The control unit analyzes, aggregates, archives and distributes the collected data packets to other locations, as desired, via a local area network (LAN) and/or a wide area network (WAN). Wireless data telemetry provides several advantages over data telemetry on wired networks. First, wireless systems are easier to install; second, installation and maintenance costs can be much lower, and third, operations can be reconfigured or relocated very quickly without consideration for rerunning wires. Fourth, wireless telemetry offers improved mobility during use.
The Federal Communications Commission (FCC) has designated three license-free bandwidth segments of the radio frequency spectrum and made them available for industrial, scientific and medical (ISM) use in the United States. These three segments are 900 MHZ, 2.4 GHz and 5.8 GHz. Anyone may operate a wireless network in a license-free band without site licenses or carrier fees, and is subject only to a radiated power restriction (i.e., a maximum of one watt radiated power). The radio signals transmitted must be spread spectrum. Foreign national spectrum regulation organizations and international telecommunications bodies have also agreed to recognize a common license-free ISM frequency at 2.4 GHz, and so a defacto international standard for license-free ISM communications has emerged. The ISM band at 2.4 GHz provides more than twice the bandwidth capacity (and is subject to far less congestion and interference) as compared to the ISM band at 900 MHZ. Several industrial nations do not permit a license-free ISM band at 900 MHZ and relatively few nations have a license-free ISM band of 5.8 GHz. However, the United States, Europe, Latin America and many Asian countries have adopted an ISM band at 2.4 GHz, the only band which so many nations offer for license-free operations.
What is needed, then, is an inexpensive, easy to use and robust data telemetry and communication system which will dynamically establish and maintain communication links, preferably operating in the common license-free ISM frequency band and providing reliable communications for a variety of users in commercial and industrial environments.
The applicant has recognized that spread spectrum transceivers pose a number of challenges not addressed by vendors of off-the-shelf RF components. For example, when switching from receive mode to transmit mode, an appropriate Voltage Controlled Oscillator must be activated and input to a modulator for transmitting data over a wide range of frequencies. Often, the modulator input sensitivity varies with transmit frequency, thus leading to a variation in modulation index for the transmitted data, with some frequencies having less than optimal modulation depth. Sub-optimally modulated data can diminish overall system performance by severely limiting range. The receiver of poorly modulated data has less signal to noise ratio margin for those frequencies subject to sub-optimally modulated data.
In accordance with the present invention, a frequency hopping spread spectrum communication system is adapted to dynamically establish and maintain communication links. The system is economically implemented at 2.4 GHz, provides an optimum balance between data rate and range and provides 9.6 kilobits per second (9.6 Kbps) data transmission over an outdoor line of sight range of approximately 35thousand meters. The communication system includes components ideally suited to specific wireless data telemetry applications. A transceiver is configured on two printed circuit cards and includes RF and computer control components in a compact package approximately the size of a deck of cards. Each transceiver includes a shielded RF board or module with a frequency hopping transmitter and receiver, an antenna, and a digital control board or module. An application interface is included to communicate with specific OEM products utilizing serial (transistor/transistor logic, TTL) or other standard interfaces. The transceiver transmits or receives on any of 550 independent, non-interfering frequencies and functions as a half duplex, bi-directional communication device. The transmit and receive functions are time interleaved in a non-overlapping fashion, consistent with the requirements of a frequency hopping radio. The transmit interval is restricted to less than 0.4 seconds on any particular frequency within a 30 second interval. In the course of a normal information exchange, a given transmission is generated on a frequency selected from a set of all available hop frequencies. The transmission is limited in duration to the availability of incoming data, and following the transmission, the radio switches to a receive mode and processes any incoming data. Once reception is complete, the transmit interval/receive interval cycle is restarted on a new frequency selected from the hop frequency set. Transmit receive cycling continues until all 75 unique frequencies in the set have been used, whereupon the frequency selection process reenters the top of the table and begins reusing the same 75frequencies.
Transmitted data is directly modulated onto a synthesized carrier by use of minimum shift keying (MSK) modulation. First and second local oscillators (LOs) are controlled in frequency by use of a single loop indirect frequency synthesis. Samples of both first and second voltage controlled oscillators (VCOs) are divided down using phase-locked loop integrated circuit elements, where each sample is compared to an onboard 8 MHZ crystal reference oscillator. During the transmit interval, a single transmitter VCO is controlled by the same device and in the same manner.
The basic transmitted signal is generated by a voltage-controlled-oscillator (VCO) that operate""s in the 2.4 to 2.4835 GHZ frequency band. The signal is then amplified by three stages of amplification. All three amplification stages and the VCO are switched ON for transmit and switched OFF for receive.
The frequency synthesizer generates the modulated transmit signal which is phase locked to the on-board 8 MHZ reference oscillator. The 8 MHZ reference is a crystal oscillator that is controlled by the off-board microprocessor. To enable a cost effective solution for the reference oscillator, an inexpensive crystal is utilized. Because a frequency tolerance of 3 parts per million (ppm) must be maintained for the transceiver to communicate, a frequency compensation routine is programmed in the microprocessor. The compensation deals with both the initial crystal manufacturing tolerance and maintaining tolerance over the specified xe2x88x9220 to 60 degrees Celsius temperature range.
The transmitted signal is generated by a VCO that is switched on during transmit and operates over a 350 MHZ tuning range roughly centered on 2.44 GHz. During operation, the VCO only tunes in the 2.4 to 2.4835 GHz band. Having a larger tuning range allows for manufacturing tolerances without the need to tune the oscillators for each manufactured board. During operation, the synthesizer chip is programmed to the required hop frequencies.
As noted above, it was recognized that when switching from receive mode to transmit mode using a classical phase-locked-loop (PLL) circuit, the modulator input sensitivity varied with transmit frequency, thus leading to a variation in modulation index for the transmitted data, with some frequencies having less than optimal modulation depth. In order to overcome this problem, a circuit was developed for use between the source of transmit data, the micro processing unit (MPU), and the transmit PLL summing junction. The circuit is called a programmable attenuator, which provides a selectively attenuated signal that is coupled into the PLL summing junction to generate a modulated data signal for transmission.
The programmable attenuation circuit dynamically adjusts the transmit data stream voltage level required to achieve a fixed level in frequency deviation based on the current operating frequency. Each VCO will provide a specific change in frequency for a given change in input control voltage signal; the change will be dependant, in part, on the present, pre-adjustment frequency. In accordance with the method of the present invention, the specific change in frequency for a given change in input control voltage signal is predicted after first having obtained a complete set of VCO characterization measurements. Those characterization measurements are stored in memory and the MPU is programmed to control the programmable attenuation circuit, providing the exact selectively attenuated data signal level required for the VCO input control signal at the required frequency.

Spread spectrum frequency hopping transceiver modulation index control


A rotating water amusement ride is described in which the passengers can in a simpler manner walk to their seats in the water vessels while keeping their feet dry. This is principally achieved by a water amusement ride, with at least one water vessel which is preferably movable in the body of water, and having a float body which is borne by the water and which has seats for accommodating passengers, wherein a platform is provided which, in a rest state of the water amusement ride, protrudes out of the water surface.

A water amusement ride of said type is known for example from DE 10 2004 062 315 A1. The float body which is borne by the water is articulatedly connected to an undercarriage, which is guided by a rail arranged on the floor of the body of water, in such a way that said float body can perform limited transverse and/or lifting movements relative to the undercarriage. Here, the undercarriage is, in one embodiment, pulled through the body of water by means of a cable pull guided over diverting rollers. Said water amusement ride is thus a water amusement ride which is equipped with rails and in which the individual water vessels travel along the rail profile in a type of stream bed.
For such rail-bound water vessels, DE 10 2006 053 664 B3 describes the provision, under the water vessel, of a special float body which is rotatably mounted on a frame. On the underside of the float body, a paddle wheel which is connected to said float body is arranged such that the float body is set in rotation as it travels through the body of water. Passengers can board said water vessels via a special landing platform at the stopping point of the water amusement ride, wherein the water vessels must dock smoothly at said stopping point.
A further water amusement ride which is reliant on rails which run within a stream or river bed is described in EP 1 671 686 B1. There, the float body and the undercarriage are coupled to one another via coupling elements. The coupling elements ensure that the float body is fixed after the sinking of the undercarriage of the water vessel.
A rotating water amusement ride, specifically a water carousel, is known from CH 183488. Said rotating water amusement ride has a float body with seats for accommodating passengers. Here, the float body is formed as an annular, buoyant shell in which seats for accommodating people are arranged. Here, the annular float body may be mounted so as to be rotatable about a mast or an anchor in the water and arranged so as to be rotatable about its fastening point by means of rudders or by means of an auxiliary motor. On the outer edge of the float body there may be provided, for example, an oblique board from which the bathers may, in the event of sufficiently fast rotation, slide into the water. Furthermore, ropes or rings may be attached to the float body in order that people swimming in the water can be pulled along. Access to the seats is realized by means of a drawbridge which the passengers must cross.