A. Cicuttin

The mirror system of COMPASS RICH-1

The architecture and the properties of the mirror system of the COMPASS RICH-1 detector, composed by 116 spherical VUV reflecting units supported by a lightweight mechanical structure, are described.

The radiator gas and the gas system of COMPASS RICH-1

The design of the COMPASS RICH-1 gas system, its operational modes, the cleaning setups for the preparation of the radiator gas and transmission measurement installations are described. The gas system in presently fully operational and satisfactory transmission of VUV light through the radiator gas has been reached.

COMPASS RICH-1

RICH-1, one of the key detectors of the COMPASS experiment at CERN SPS, is described. Photon detectors are MWPCs equipped with CsI photo-cathodes.

Frequency Dependence of Electrical Coupling in Deiters″ Cells of the Guinea Pig Cochlea

Immunolabeling with antibodies against connexins 26 and 30 showed that, in the guinea pig cochlea, supporting Deiters″ cells are massively interconnected and form an orderly network within the organ of Corti. In paired patch-clamp recordings the coupling ratio (CR) of adjacent Deiters″ cells at the apex of the cochlea (∼0.31) was 3-fold smaller than in isolated cell pairs due to shunting afforded by multicellular connectivity. With sinusoidal current stimuli the delay in signal propagation between adjacent cells increased with increasing frequency whereas the amplitude did not change significantly up to 200 Hz (corner frequency Fc ∼220 Hz). Depolarizing voltage commands applied to an outer hair cell (OHC) elicited outward potassium currents in the OHC and inward currents in the abutting Deiters″ cells, supplying direct evidence for potassium buffering in the organ of Corti. Computational analysis indicates that electrical signals injected into a Deiters″ cell are transmitted across a network segment spanning 8 cell diameters. Thus electrical coupling in the organ of Corti is unlikely to influence the selectivity of frequency filtering performed mechanically by the mammalian cochlea.

Entropic approach to information coding in DNA molecules

The amount of information carried by the binding site patterns in the deoxyribonucleic acid (DNA) molecules is subject of interpretation in the light of the maximum entropy methods, within the framework of classical information theory, in view of characterizing the sequence conservation at nucleic acid binding sites.

A Block-Based Open Source Approach for a Reconfigurable Virtual Instrumentation Platform Using FPGA Technology

Recent advances in field-programmable gate arrays (FPGA) have made it possible to efficiently build various complex hardware emulation systems. This technology promises new levels of system integration onto a single FPGA, but also presents significant challenges to designers. The proposed reconfigurable virtual instrumentation (RVI) project leverages the latest FPGA technological advances. Its goal is to provide a low-cost reusable hardware/software platform for the emulation of multiple electronic and scientific instrumentation systems. Unlike previous approaches, the proposed architecture leverages a block-based design methodology that emphasizes design reuse as an effective mean to cope with the challenge of a growing design complexity. An open source approach to the project allows future contributors to rely on previously developed software, making the emulation of new instruments increasingly more cost-effective. This paper details the architecture of the RVI system with its main building blocks. It also illustrates its capabilities with multiple implementation examples

The COMPASS RICH-1 read-out system

This paper describes the reconfigurable read-out system for the 82944 RICH-1 channels of the COMPASS experiment (NA58) at CERN. The system is based on 192 identical large front-end boards (BORA board). BORA was designed for acquiring, digitizing, threshold subtracting and transmitting event data. The overall operation of the board is controlled and supervised by a DSP tightly interacting with an FPGA that acts as a parallel co-processor. The DSP allows characterizing each analog channel by locally calculating noise and pedestal. Each BORA communicates with the outside world through two optical fibers and through a dedicated DSP network. One optical fiber is used to receive event triggers, and the other one is used to transmit event data to subsequent processing stages of the acquisition system. The DSP network allows reconfiguring and reprogramming the DSPs and FPGAs as well as acquiring sample events to visualize the overall operation of the system. The whole RICH has eight DSP networks working in parallel. These networks are handled by DOLINA, a PC resident multiprocessor board containing eight DSPs. Each network is formed by 24 BORA DSPs and 1 DOLINA DSP. The read-out system can steadily work up to a trigger rate of 75 kHz with maximum pixel occupancy of 20%, reaching a transmission data rate of 5.13 Gbytes/s.

Biogeochemical fingerprints of life: earlier analogies with polar ecosystems suggest feasible instrumentation for probing the Galilean moons

We base our search for the right instrumentation for detecting biosignatures on Europa on the analogysuggestedbythe recent workon polarecosystemsin theCanadianArcticatEllesmereIsland.In that locationsulphurpatches(analogoustotheEuropanpatches)areaccumulatingonglacialicelyingoversaline springs rich in sulphate andsulphide. Their work reinforces earlieranalogies in Antarctic ecosystemsthatare appropriate models for possible habitats that will be explored by the European Space Agency JUpiter ICy Moons Explorer (JUICE) mission to the Jovian System. Its Jupiter Ganymede Orbiter (JGO) will include orbits around Europa and Ganymede. The Galileo orbital mission discovered surficial patches of non-ice elements on Europa that were widespread and, in some cases possibly endogenous. This suggests the possibility that the observed chemical elements in the exoatmosphere may be from the subsurface ocean. Spatial resolution calculations of Cassidy and co-workers are available, suggesting that the atmospheric S content can be mapped by a neutral mass spectrometer, now included among the selected JUICE instruments. In some cases, large S-fractionations are due to microbial reduction and disproportionation (although sometimes providing a test for ecosystem fingerprints, even though with Sim - Bosak - Ono we maintain that microbial sulphate reduction large sulphur isotope fractionation does not require disproportionation. We addressthe questionof the possible roleofoxygen in the Europanocean. Instrument issues are discussed for measuring stable S-isotope fractionations up to the known limits in natural populations of δ 34 &�70‰. We state the hypothesis of a Europa anaerobic oceanic population of sulphate reducers and disproportionatorsthatwould havethe effect of fractionating the sulphatethatreachesthe low- albedo surficial regions. This hypothesis is compatible with the time-honoured expectation of Kaplan and co-workers (going back to the 1960s) that the distribution range of 32 S/ 34 S in analysed extra-terrestrial material appears to be narrower than the isotopic ratio of H, C or N and may be the most reliable for estimating biological effects. In addition, we discuss the necessary instruments that can test our biogenic hypothesis. First of all we hasten to clarify that the last-generation miniaturized mass spectrometer we discuss in the present paper are capable of reaching the required accuracy of ‰ for the all-important measurements with JGO of the thin atmospheres of the icy satellites. To implement the measurements, we single out miniature laser ablation time-of-flight mass spectrometers that are ideal for the forthcoming JUICE probing of the exoatmospheres, ionospheres and, indirectly, surficial low-albedo regions. Ganymedes surface, besides having ancient dark terrains covering about one-third of the total surface, has bright terrains of more recent origin, possibly due to some internal processes, not excluding biological ones. The geochemical test could identify bioindicators on Europa and exclude them on its large neighbour by probing relatively recent bright terrains on Ganymedes Polar Regions.

Building an Evolvable Low-Cost HW/SW Educational Platform--Application to Virtual Instrumentation

This paper describes a hardware/software FPGA-based platform. Its goal is to provide a reusable low-cost system for teaching system-level design, with an emphasis on design reuse as an effective mean to cope with an ever growing design complexity. An open source strategy promotes cross-university collaboration by relying on previously developed software. The first implementation examples target the area of Reconfigurable Virtual Instrumentation (RVI), which in turn provides a low-cost solution for teaching electronic instrumentation.

MAXIMUM ENTROPY IMPROVEMENT OF X-RAY DIGITAL MAMMOGRAMS

Our approach to X-ray digital image enhancement was based on entropy maximization, which allows distributions to be estimated in cases when incomplete or corrupt information is only available. In data analysis, maximum entropy (ME) techniques are generally used to reconstruct positive distributions, such as images and spectra, from blurred or noisy data. Within this framework, positive distributions ought to be assigned probabilities which are based on the entropy of these distributions. If we consider a complete collection of images corresponding to all possible intensity distributions, then measurements act as a filter over the collection by restricting our attention to the images that satisfy the data with noise. Among these, a natural choice may be the one that could have arisen in the maximum number of ways, depending on our counting rule.