Trigger Module Research Articles

Specific Recognition of Apoptotic Cells Reveals a Ubiquitous and Unconventional Innate Immunity

The purpose of physiological cell death is the noninflammatory clearance of cells that have become inappropriate or nonfunctional. Consistent with this function, the recognition of apoptotic cells by professional phagocytes, including macrophages and dendritic cells, triggers a set of potent anti-inflammatory responses manifest on multiple levels. The immediate-early inhibition of proinflammatory cytokine gene transcription in the phagocyte is a proximate consequence of recognition of the apoptotic corpse, independent of subsequent engulfment and soluble factor involvement. Here, we show that recognition is linked to a characteristic signature of responses, including MAPK signaling events and the ablation of proinflammatory transcription and cytokine secretion. Specific recognition and response occurs without regard to the origin (species, tissue type, or suicidal stimulus) of the apoptotic cell and does not involve Toll-like receptor signaling. These features mark this as an innate immunity fundamentally distinct from the discrimination of "self" versus "other" considered to be the hallmark of conventional immunity. This profound unconventional innate immune discrimination of effete from live cells is as ubiquitous as apoptotic cell death itself, manifest by professional and nonprofessional phagocytes and nonphagocytic cell types alike. Innate apoptotic immunity provides an intrinsic anti-inflammatory circuit that attenuates proinflammatory responses dynamically and may act systemically as a powerful physiological regulator of immunity.

Digital acquisition systems for the EDELWEISS experiment

We describe the digital acquisition systems used in the EDELWEISS experiment. In the EDELWEISS-I experiment, both charge and phonon signals are continuously digitized after preamplification and transferred to a computer using a high-speed DMA channel via a 1.5Gbit/s optical fibre link, decoupling the detectors from the acquisition computer. Both phonon and charge triggers are defined numerically, without any analog triggering module, allowing a flexible filtering and trigger definition. The performances reached in this system are described, together with the improvements presently realized for the second phase of the experiment, EDELWEISS-II, involving up to 120 detectors.

A fully digital architecture for trigger circuits in programmable logic

A digital trigger module for high-resolution nuclear spectroscopy, composed of three filters operating in parallel and a resolver, is introduced. The single filters are optimized so as to allow low-level discrimination as well as high time-resolving capabilities. Particular care is taken in order to minimize hardware resources. In the case of a high-resolution gamma spectroscopy system based on quasi-coaxial HPGe detectors, the lower threshold discrimination level can be as low as 4 keV while measuring the 1.17-MeV /sup 60/Co line. The capability of discriminating gamma photons impinging almost at the same time is limited in practice only by the intrinsic charge-collection time of the detector. The circuit is implemented in a programmable device (field-programmable gate array) and exploits at best hardware resources already allocated to the filter for energy estimate. A built-in calibration circuit is also implemented, which allows easy setting of discrimination thresholds. It is shown that the devised architecture can be easily upgraded to accommodate a higher number of parallel filters if a further increase of circuit performance is required.

MUSE: an integrated trigger and readout control system for CHIMERA

The CHIMERA 4/spl pi/ detector trigger system is described. The trigger decisions are based on a combination of geometrical multiplicity of detected particles and other logic signals. The trigger can manage the buffer memory of the used analog to digital converters. This allows performance of parallel data conversion and readout and substantial improvement of the acquisition system dead-time performances. The trigger module generates all the necessary gate signals for the converters and the control signals necessary to synchronize the readout. It also allows the remote control of the whole system.

A fast programmable trigger system for the WASA experiment

A programmable fast trigger system for the WASA experiment at The Svedberg Laboratory, Uppsala, Sweden is presented. For minimum signal delay times the hardware architecture is divided into two levels. The first level mainly handles fast signals from about 350 plastic scintillating detectors forming hit cluster multiplicity decision, restricting the total number of reaction products. Track alignment checks, coplanarity and deposited energy checks put further restrictions on the acquired events. The first level incorporates 40 generic trigger modules, prescalers, scalers, and pattern units. To minimize dead-time losses the first level is working in a feed-through mode with no external strobe signals required, the total delay amounts to 120 ns. The second level utilizes a fast cluster finding algorithm implemented in 40 trigger modules operating on signals from an array of 24/spl times/48 CsI crystals. Background is filtered away by restricting the spatial distribution and the number of reaction products. The output from the cluster analyzing second level is provided within 115 ns. The trigger utilizes programmable logic devices and. is fully reconfigurable. An I/sup 2/C-based slow control system is provided for setting discriminator thresholds, pulse duration, channel masking, signal delay, and setup of logic conditions.

Interactions of human NKG2D with its ligands MICA, MICB, and homologs of the mouse RAE-1 protein family.

NKG2D is an activating receptor that is expressed on most natural killer (NK) cells, CD8 alphabeta T cells, and gammadelta T cells. Among its ligands is the distant major histocompatibility complex class I homolog MICA, which has no function in antigen presentation but is induced by cellular stress. To extend previous functional evidence, the NKG2D-MICA interaction was studied in isolation. NKG2D homodimers formed stable complexes with monomeric MICA in solution, demonstrating that no other components were required to facilitate this interaction. MICA glycosylation was not essential but enhanced complex formation. Soluble NKG2D also bound to cell surface MICB, which has structural and functional properties similar to those of MICA. Moreover, NKG2D stably interacted with surface molecules encoded by three newly identified cDNA sequences (N2DL-1, -2, and -3), which are identical to the human ULBP proteins and may represent homologs of the mouse retinoic acid-early inducible family of NKG2D ligands. Because of the substantial sequence divergence among these molecules, these results indicated promiscuous modes of receptor binding. Comparison of allelic variants of MICA revealed large differences in NKG2D binding that were associated with a single amino acid substitution at position 129 in the alpha2 domain. Varying affinities of MICA alleles for NKG2D may affect thresholds of NK-cell triggering and T-cell modulation.

Design and performance of a data acquisition system for VUB-PET

A flexible and high-speed VME-based data acquisition system (DAQ) has been designed to process data from the University of Brussels (VUB) small-animal positron emission tomography (PET) system. The core tasks of the system are performed by two custom VME modules: a trigger module and a fast readout module (FRO). Following the detection of a valid coincidence event by the trigger unit, the raw data from all analog-to-digital converter channels involved are read out simultaneously via a FRO. An onboard digital signal processor (DSP) processor checks and calibrates these data. To increase the transfer throughput of the list mode data to a SUN Ultra Sparc 1 workstation, the DSP processor compresses the data format to a 6-byte data packet per event. The maximum average sustained acquisition rate of the system is 200000 counts per second (cps), while peak rates up to 2 Mcps can be handled. The DAQ also provides online measurement of the random event rate, the single event rate and event losses due to electronic dead time.

A self‐tuning run‐by‐run process controller for processes subject to random disturbances

In this paper a self‐tuning run‐by‐run process controller is presented. The controller has the capability of choosing a control parameter dynamically in response to the underlying process disturbances. There are two modules in this controller: a self‐tuning loop trigger module and a run‐by‐run feedback control module. In the self‐tuning loop trigger module, two EWMA control charts are used sequentially to determine if there is a large or medium shift in the process output and to trigger a new self‐tuning loop accordingly. In the run‐by‐run feedback control module, the control parameter and control model are re‐tuned sequentially and a new process recipe is generated, on a run‐by‐run basis, to compensate for the process output's deviation from the target. Monte Carlo simulation results show that the self‐tuning run‐by‐run process controller is superior to the current run‐by‐run process controller with a fixed control parameter.

A fast programmable multiplicity trigger system

A fast, programmable trigger module has been designed and built. It consists of commercially available components mounted on two multilayer boards and resides in a CAMAC environment. The module has been designed to provide a first-level trigger primarily for the detection of proton pairs from proton–proton bremsstrahlung measurements. The design considerations and the performance of the module are discussed.

Hardware trigger system for Fermilab E866

E866 is the fourth experiment to be performed with the Fermilab Meson East spectrometer. Originally constructed in 1980 for E605, this spectrometer has since been used for E772 and E789. During these three experiments, the hardware trigger depended on components dating from the early 1970s. The trigger system was rebuilt for E866 to improve its reliability and increase its flexibility. The new system incorporates several new modules designed and built specifically for this experiment. Notably, a custom Track Correlator combines the features of a 16-bit memory lookup and a 12-bit prescaler into a single extremely fast CAMAC module. The new hardware trigger system and modules are described, and the system performance during E866 is discussed.

A modified stopped-flow apparatus for time-resolved protein phosphorescence

A type of commercial apparatus was modified and integrated in order to implement the detection of time-resolved protein phosphorescence in the stopped-flow technique. Laser excitation, photomultiplier protection from the intense fluorescence pulse, fluorescence integration, and data acquisition are all synchronized by a trigger module that takes over standard computer control of the stopped-flow apparatus. A detailed protocol is given for effective deoxygenation of the sample and flow lines and for avoiding contamination of the solutions by quenching impurities. The performance of the apparatus was tested by comparing the phosphorescence decay kinetics of the protein horse liver alcohol dehydrogenase in the stopped-flow apparatus and in a standard phosphorimeter. The time resolution of phosphorescence detection in the stopped-flow apparatus is 10 ms and the sensitivity in terms of chromophores concentration is about 0.1 μM.

A fast total energy trigger unit for a CsI calorimeter

A fast total energy trigger module for use with the CsI calorimeter of the Crystal Barrel experiment at LEAR is described. The unit intercepts and sums the data during the transfer of the digital output of the LeCroy FERA ADCs to the 1190 memory modules. Comparing the digital sum with two preset levels then generates outputs to the trigger logic in less than 40 μs from the start of the input gate signal to the FERA ADCs. This fast response allows the energy sum signals to be included in the level one trigger logic.

Initialization issues in asynchronous circuit synthesis

A design specification is said to be functionally uninitializable if an initializable implementation cannot be obtained. Due to the absence of any initialization sequence, a fault simulator or test generator that assumes an unknown starting state will be completely ineffective for uninitializable circuits. We present a novel procedure for synthesizing initializable asynchronous circuits from functionally uninitializable Signal Transition Graphs (STG). After characterizing the necessary conditions for functional uninitializability, we propose a technique that transforms the original STG into an equivalent, functionally initializable STG. We show that the presence of concurrency provides the designer with an extra degree of flexibility when implementing the circuit. It is shown that initializability can be achieved by sacrificing minimal concurrency and without violating the syntactic properties of the STG required for a hazard-free implementation. The synthesis of a trigger module illustrates this procedure.

Results from a MA16-based neural trigger in an experiment looking for beauty

Results from a neural-network trigger based on the digital MA16 chip of Siemens are reported. The neural trigger has been applied to data from the WA92 experiment, looking for beauty particles, which have been collected during a run in which a neural trigger module based on Intel's analog neural chip ETANN operated, as already reported. The MA16 board hosting the chip has a 16-bit I O precision and a 53-bit precision for internal calculations. It operated at 50 MHz, yielding a response time for a 16 input-variable net of 3 μs for a Fisher discriminant (1-layer net) and of 6 μs for a 2-layer net. Results are compared with those previously obtained with the ETANN trigger.

Beam tests of the prototype level-1 trigger system and drift tubes with field-shapers proposed for the SDC barrel muon system

Mini-tower beam tests were carried out at a test beam line of KEK-PS in order to study the performance of the prototype level-1 trigger system and drift tubes with field-shapers originally designed for the SDC barrel muon detector at the SSC. A mini-tower of 10 layers, 31 drift tubes in total, and a prototype level-1 trigger module were designed and fabricated for the tests. The spatial resolution of about 230 μm was obtained for the tubes. Relatively high rates of multi-pulse signals were observed for most of the tubes. The trigger module designed at KEK using a logic delta-T method was studied for various trigger logics and its performance was found to be very satisfactory.

RESULTS FROM A NEURAL TRIGGER BASED ON THE MA16 MICROPROCESSOR

Results from a neural-network trigger based on the digital MA16 chip of Siemens are reported. The neural trigger has been applied to data from the WA92 experiment, looking for beauty particles, which have been collected during a run in which a neural trigger module based on Intel’s analog neural chip ETANN operated, as already reported. The MA16 has a precision of 16 bits for input variables, 16 bits for weights, 16 bits for scalar multipliers modifying the transfer function shape, 47 bits for thresholds, 53 bits for internal calculations, 38 bits for the output. Of the latter only 16 bits are used in the MA16 board, as input to the transfer function inplemented on 16-bit addressable EPROM’s. The MA16 board operated at 50 MHz, yielding a response time for a 16 input variable net of 3 μs for a Fisher discriminant (1-layer net) and of 6 μs for a 2-layer net. Results are compared with those previously obtained with the ETANN trigger.

Results from an on-line non-leptonic neural trigger implemented in an experiment looking for beauty

Results from a non-leptonic neural-network trigger hosted by experiment WA92, looking for beauty particle production from 350 GeV negative pions on a fixed Cu target, are presented. The neural trigger has been used to send events selected by means of a non-leptonic signature based on microvertex detector information to a special data stream, meant for early analysis. The non-leptonic signature, defined in a neural-network fashion, was devised so as to enrich the selected sample in the number of events containing C3 secondary vertices (i.e., vertices having three tracks with sum of electric charges equal to +1 or −1), which are sought for further analysis to identify charm and beauty non-leptonic decays. The neural trigger module consists of a VME crate hosting two MA16 digital neural chips from Siemens and two ETANN analog neural chips from Intel. During the experimental run, only the ETANN chips were operational. The neural trigger operated for two continuous weeks during the WA92 1993 run. For an acceptance of 15% for C3 events, the neural trigger yields a C3 enrichment factor of 6.6–7.1 (depending on the event sample considered), which multiplied by that already provided by the standard trigger leads to a global C3 enrichment factor of ∼ 150. In the event sample selected by the neural trigger, one every ∼ 7 events contains a C3 vertex. The response time of the neural trigger module is 5.8 μs.

The CHAOS second level trigger. A fast, programmable ECL trigger for a magnetic spectrometer using multiwire proportional chambers

A versatile second level trigger has been developed for the CHAOS facility at TRIUMF using fast ECLine trigger modules augmented by some specially constructed modules. It consists of a primary stage and two optional secondary stages. The primary track finding stage is capable of making a decision based on track vertex, polarity and momentum. The next stage is able to reject events based on the correlation between track momentum and scattering angle. The third stage can make a cut on the sum of the momenta of two tracks. In addition there is an extra parallel stage that is responsible for ensuring that the beam particle has the correct incoming trajectory. All stages are programmable and, depending on experimental conditions and trigger configuration, usual rejection times are between 2 and 4 μs.

AN ON-LINE NON-LEPTONIC NEURAL TRIGGER APPLIED TO AN EXPERIMENT LOOKING FOR BEAUTY

Results from a non-leptonic neural-network trigger hosted by experiment WA92, looking for beauty particle production from 350 GeV π− on a Cu target, are presented. The neural trigger has been used to send on a special data stream (the Fast Stream) events to be analyzed with high priority. The non-leptonic signature uses microvertex detector data and was devised so as to enrich the fraction of events containing C3 secondary vertices (i.e, vertices having three tracks whith sum of electric charges equal to +1 or -1). The neural trigger module consists of a VME crate hosting two ETANN analog neural chips from Intel. The neural trigger operated for two continuous weeks during the WA92 1993 run. For an acceptance of 15% for C3 events, the neural trigger yields a C3 enrichment factor of 6.6–7.1 (depending on the event sample considered), which multiplied by that already provided by the standard non-leptonic trigger leads to a global C3 enrichment factor of ≈150. In the event sample selected by the neural trigger for the Fast Stream, 1 every ≈7 events contains a C3 vertex. The response time of the neural trigger module is 5.8 μs.

Triggering module for waveform digitization

A full circuit description is provided for a triggering module used to assist a small laboratory computer in digitizing muscle force- and EMG waveforms. During the stimulation of individual motor units using a standard fatigue test, a train of 13 pulses are delivered at a rate of 40 pps either intracellularly to a motor neuron, or extracellularly to functionally isolated single motor axons from among divided ventral-root nerve filaments. Trains are delivered at a rate of 1/s for the duration of the test, which may range from 120 to 3600 s. Both the force and EMG profiles undergo changes during such tests and the quantification of parameters associated with their waveforms are of interest to neurobiologists. The triggering module allows a typical small laboratory computer to capture user-selected waveforms and thereby reduces the programming problems, timing constraints, storage requirements and analysis time associated with obtaining these parameters. The versatile circuit may be easily adapted to solve similar data-acquisition problems. The method was implemented on an Apple Macintosh II computer but can also be applied to other systems equipped with appropriate software and a data-acquisition card.