Low-voltage double-sampled ΣΔ converters

An obvious way of achieving higher signal-to-noise ratio in oversampled data converters is by increasing the effective sampling rate. If all other components are kept constant, this translates into integrators with larger bandwidth that in turn results in higher overall power consumption. This work introduces the fully floating switched-capacitor configuration as a simple and robust technique to effectively double the sampling rate of oversampled data converters without compromising any aspect of the performance and yet maintaining the power levels of the conventional approach. The use of internal decimation in the switched-capacitor ladder structure of the digital-to-analog converter further helps in achieving the power budget goals. These converters have been implemented with circuitry capable of operating at a minimum supply voltage of 1.8 V under worst case process and temperature conditions and using clock bootstrapping for the transfer gates. The bootstrapping circuit described here uses a single internal capacitor and has functionality that limits the maximum clock voltage to safe levels under a wide range of supply voltages. The prototype was fabricated in a 0.5-μm CMOS double-poly technology. The analog-to-digital converter occupies a die area of 0.11 mm² dissipating 550 μW while the digital-to-analog converter occupies 0.28 mm² dissipating 600 μW     

A 2.7-V 11.8-mW baseband ADC with 72-dB dynamic range for GSMapplications

A receive baseband analog-to-digital converter (ADC) for a GSM cellular radio system is presented. Low voltage and low power techniques have been applied across many aspects of the design. The circuit consists of two second-order double-sampled semi-bilinear ΣΔ modulators followed by two 576-tap digital finite-impulse response (FIR) GSM-channel filters with offset calibration. The complete ADC achieves a dynamic range of 72 dB and dissipates 11.8 mW from a 2.7-V supply. The area is 1.6 mm² in a 0.5-μm n-well double-poly triple-metal CMOS process     

Modeling and simulation of the anode in direct ethanol fuels cells

Mathematical modeling has been extensively applied to the study and development of fuel cells. In this work, the objective is to characterize a mechanistic model for the anode of a direct ethanol fuel cell and perform appropriate simulations.     

Injection-Level Studies in Neutron-Irradiated Silicon

The dependence of carrier lifetime on excess density was investigated for neutron-irradiated silicon. Five bulk specimens of n-type (1.0 to 55 ohm-cm) and five of p-type material (2.2 to 56 ohm-cm) were employed. In all cases the lifetime was constant at low excess densities, increased to a value several times larger at excess densities near the equilibrium carrier density, and then decreased. An analysis of the data was performed on the basis of recombination at disordered regions. The effective barrier heights associated with disordered regions were small, about 0.05 eV in n-type silicon and about 0.07 eV in p-type material. These values represent a weighted average for those regions participating in recombination and tend to favor low values. Capture probability ratios and other parameters were also obtained.     

Design,Synthesis, and Preliminary Biological Evaluation of Pyrrolo[3,4‐c]quinolin‐1‐one and Oxoisoindoline Derivatives as Aggrecanase Inhibitors

A small set of aggrecanase inhibitors based on the pyrrolo[3,4‐c]quinolin‐1‐one or oxoisoindoline frameworks bearing a 4‐(benzyloxy)phenyl substituent and different zinc binding groups were rationally designed and evaluated in silico by docking studies using the crystal structure of the ADAMTS‐5 catalytic domain (PDB code: 3B8Z). The designed compounds were synthesized via straightforward routes and tested for their potential inhibitory activity against ADAMTS‐5 and ADAMTS‐4. Among the compounds containing the pyrrolo[3,4‐c]quinolinone tricyclic system, hydroxamate derivative 2 b inhibited both ADAMTS‐5 and ADAMTS‐4, with IC₅₀ values in the submicromolar range and an inhibitory profile very similar to that of reference carboxylate derivative 11 . Conversely, the corresponding carboxylate derivative 2 a was significantly less active and unable to discriminate between ADAMTS‐5 and ‐4. The structure–activity relationship analysis of pyrroloquinolinone derivatives 2 a – i suggests that the carboxylate or hydroxamate groups of compounds 2 a , b play a key role in the interaction of these compounds with ADAMTS‐5 and ‐4. On the other hand, the oxoisoindoline derivatives 3 a , b lack significant ADAMTS‐4 inhibitory activity and inhibit ADAMTS‐5 showing IC₂₅ values in the micromolar range.     

Thymosin β4 Is an Endogenous Iron Chelator and Molecular Switcher of Ferroptosis

Thymosin β4 (Tβ4) was extracted forty years agofrom calf thymus. Since then, it has been identified as a G-actin binding protein involved in blood clotting, tissue regeneration, angiogenesis, and anti-inflammatory processes. Tβ4 has also been implicated in tumor metastasis and neurodegeneration. However, the precise roles and mechanism(s) of action of Tβ4 in these processes remain largely unknown, with the binding of the G-actin protein being insufficient to explain these multi-actions. Here we identify for the first time the important role of Tβ4 mechanism in ferroptosis, an iron-dependent form of cell death, which leads to neurodegeneration and somehow protects cancer cells against cell death. Specifically, we demonstrate four iron²⁺ and iron³⁺ binding regions along the peptide and show that the presence of Tβ4 in cell growing medium inhibits erastin and glutamate-induced ferroptosis in the macrophage cell line. Moreover, Tβ4 increases the expression of oxidative stress-related genes, namely BAX, hem oxygenase-1, heat shock protein 70 and thioredoxin reductase 1, which are downregulated during ferroptosis. We state the hypothesis that Tβ4 is an endogenous iron chelator and take part in iron homeostasis in the ferroptosis process. We discuss the literature data of parallel involvement of Tβ4 and ferroptosis in different human pathologies, mainly cancer and neurodegeneration. Our findings confronted with literature data show that controlled Tβ4 release could command on/off switching of ferroptosis and may provide novel therapeutic opportunities in cancer and tissue degeneration pathologies.     

Fully integrated voiceband codec in a standard digital CMOS technology

A 2.7-V complete voiceband codec with high-performance speech interfaces is presented. It includes a low-noise microphone preamplifier and loudspeaker/earpiece drivers. In the 4-kHz signal bandwidth, the ADC achieves a dynamic range of 80 dB and a full scale S/(THD + N) ratio of 71 dB, while the DAC performs 84 dB and 75 dB, respectively. These performances have been obtained in a pure digital low-cost CMOS process. The only components used are standard nMOS and pMOS transistors, parasitic vertical PNP bipolar transistors, unsalicided poly resistors, nonlinear poly-nwell capacitors, and a few small linear capacitors made with a sandwich of five metals and poly. The active area is 2.7 mm/sup 2/ in a 0.35-/spl mu/m, five metal levels, standard digital CMOS technology. Power dissipation is 12 mW. The cell can be easily migrated in more advanced processes with area reduction. A migration in a 0.18-/spl mu/m digital CMOS process has been achieved.     

Debugging a Distributed Computing System

In this paper we discuss the issues involved in debugging a provide distributed computing system. We describe the major differences between debugging a distributed system and debugging a sequential program. We suggest a methodology for distributed debugging, and we propose various tools or aids.     

Technetium-99m teboroxime regional myocardial washout in subjects with and without coronary artery disease

The aim of this study was to test the hypothesis that regional myocardial washout of technetium-99m teboroxime is slowed in the presence of coronary stenosis. Washout was assessed in 33 catheterized patients and in 13 with a low likelihood of coronary artery disease, using a triple detector camera and dynamic single-photon emission computed tomography, with serial 1-minute acquisitions after injection of 20 to 25 mCi of teboroxime at the third minute of adenosine-induced hyperemia. Washout was measured as the percent change in counts between the first, second and third minutes after injection, as measured in 6 short-axis myocardial regions of interest. Myocardial regions were classified as ischemic (> or = 50% diameter stenosis and no prior myocardial infarct), infarcted, normal (no significant coronary stenosis) or "low likelihood" (from the 13 patients with a low likelihood of coronary artery disease). Teboroxime washout was significantly (p < 0.001) slowed in the ischemic myocardium (12.7 +/- 8.3%) compared with the normal (18.5 +/- 5.7%), low-likelihood (17.8 +/- 6.1%) and infarcted (17.8 +/- 4.4%) zones. There was regional variability in washout rates (% washout/min), with the anterior wall having the lowest (13.8 +/- 3.4%/min) and the inferior wall the highest (20.7 +/- 7.9%/min) values. In regard to individual coronary territories, 21 of 41 ischemic, noninfarcted territories (51%) had abnormal washout compared with 3 of 43 normal territories (7%) (p = 0.001). In conclusion, regional washout of teboroxime is detectably slowed in ischemic, noninfarcted myocardium. The clinical value of washout analysis in teboroxime single-photon emission computed tomography warrants further investigation.     

Assessing the natural ventilation potential of the Basel region

A method is proposed to assess the natural ventilation potential (NVP) of the Basel Region, Switzerland, by taking into account the most comprehensive set of factors involved in natural ventilation. These factors are either driving forces, such as wind pressure and stack effect, or constraints, like noise pollution and atmospheric pollution. The process considers these factors in an ordinal qualitative scale and gives its result in this same scale. Climatic data are extracted from a mesoscale atmospheric simulation model referred to as Finite Volume Model (FVM), accounting for the effect of the urban fabric and taking as boundary conditions data coming from a model of the Swiss national weather service (MeteoSwiss). FVM provides an urban turbulence module which specifically simulates the effects of urban areas on the meteorology.