Design of a Novel Envelope Detector for Fast-Settling Circuits

A novel envelope detector structure that overcomes the traditional tradeoff required in these circuits, improving both the tracking and keeping of the signal, which is specially advantageous for fast-settling circuits, is proposed in this paper. The method relies on holding the signal by two capacitors in parallel, discharging one when the other is in the hold mode and employing the held signals to form the output. Results show a savings greater than 60% of the capacitor area for the same ripple ( < 1%) and a release time constant that is 13 times smaller than that obtained by conventional circuits.     

Modular P?OP Ligands in Rhodium‐Mediated Asymmetric Hydrogenation: A Comparative Catalysis Study

Highly efficient and enantioselective hydrogenation reactions for α‐(acylamino)acrylates, itaconic acid derivatives and analogues, α‐substituted enol ester derivatives, and α‐arylenamides (25 substrates) catalyzed by chiral cationic rhodium complexes of a set of P OP ligands have been developed. The catalytic systems derived from these P OP ligands provided a straightforward access to enantiomerically enriched α‐amino acid, carboxylic acid, amine, and alcohol derivatives that are valuable chiral building blocks. Excellent efficiencies (full conversion in all cases) and extremely high enantiomeric excesses (94–99% ee) were achieved for a wide range of α‐substituted enol ester derivatives, regardless of the substitution pattern. The R‐oxy group of the ligand (methoxy or triphenylmethoxy) strongly influences the enantioselectivity and catalytic activity. Greater steric bulk around the metal centre correlated to greater (or similar) enantioselectivity, but also to slower hydrogenation. Furthermore, the hydrogenation rates observed with the four model substrates follow the same trend, independently of the R‐oxy group of the ligand: methyl 2‐acetamidoacrylate>dimethyl itaconate>1‐phenylvinyl acetate>N‐(1‐phenylvinyl)acetamide. A substrate‐to‐catalyst ratio (S/C) of up to 10,000:1 was sufficient for total hydrogenation of a model substrate of intermediate reactivity (dimethyl itaconate), and did not imply any loss in conversion or enantioselectivity.     

Indoor and outdoor air concentrations of BTEX and determinants in a cohort of one-year old children in Valencia, Spain

BTEX is the commonly used term for a group of toxic compounds (benzene, toluene, ethyl benzene, ortho-xylene and meta- and para-xylene), some of which, most notably benzene, are known carcinogens. The aim of this study is to measure the BTEX levels both inside and outside the homes of 352 one-year old children from the Valencia cohort of the INMA study (Spain) and to analyze the determinants of these levels. Passive samplers were used to measure BTEX levels during a 15 day period and a questionnaire was administered to gather information on potentially associated factors (sociodemographics, residential conditions, and lifestyle). The average concentrations of benzene, toluene, ethyl benzene, ortho-xylene, and meta- and para-xylene were 0.9, 3.6, 0.6, 0.6, and 1.0 μg/m³, respectively. On average, the indoor levels of all the compounds were approximately 2.5 times higher than those observed outdoors. Factors associated with higher BTEX concentrations inside the home were being the child of a mother of non-Spanish origin, living in a house that had been painted within the last year, living in an apartment, and not having air conditioning. Higher outdoor concentrations of BTEX depend on the residence being situated in a more urban zone, being located within the city limits, having living in a building with more than one story, residing in an area with a greater frequency of traffic, and the season of the year in which the sample was taken. The data thus obtained provide helpful information not only for implementing measures to reduce exposure to these pollutants, but also for evaluating the relation between such exposure and possible health risks for the children in the cohort.     

A voltage-control algorithm for a DC link of an active power filter

Synthesis of the PI-control law of voltage for the dc link of an active power filter that carries out preliminary charging of the capacitor bank with a desired quality of transient processes, as well as stabilization of the controlled variable at a given level with zero static error, is performed in this paper.     

High-order coplanar waveguide (CPW) filters implemented by means of open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs)

In this paper, it is demonstrated that transmission lines loaded with a combination of open split ring resonators (OSRRs) and open complementary split ring resonators (OCSRRs) are useful for the design of high-order band pass filters subjected to standard responses. Specifically, we present a 7-pole Chebyshev band pass filter in coplanar waveguide technology. The device is compact and filter performance is good, including a wide stopband response. With this work, we extend our previous work on the applications of OSRR- and OCSRR-loaded lines to the design of highly selective filters.     

Electro-oculogram in multiple system and late onset cerebellar atrophies

The present investigation uses electrooculogram to evaluate multiple system atrophy (MSA) and late onset cerebellar atrophies (LOCAs), both idiopathic (ILOCA) and late onset autosomal dominant cerebellar ataxia (ADCA). Forty cases were clinically examined using scales for cerebellar, pyramidal, parkinsonian, mental status and neuroimaging quantitative evaluations. The patients were classified into three groups: olivopontocerebellar atrophy (OPCA), striatonigral degeneration (SND), Shy-Drager syndrome (SDS), and LOCA. We have used direct current electro-oculography in order to establish their validity in making the diagnosis. Cerebellar signs were significantly correlated with impaired VOR-fix gain and OKN, abnormalities of saccades, and reduced smooth pursuit gain (p < 0.05). Pons atrophy was significantly correlated with impaired VOR-fix gain (p < 0.01), abnormalities of saccades (p < 0.01), and reduced smooth pursuit gain (p < 0.05). Cerebellar hemisphere atrophy was significantly correlated only with impaired VOR-fix gain (p < 0.05), and medulla oblongata atrophy only with abnormalities of saccades (p < 0.05). Gaze-evoked nystagmus was found in 42.8% of patients with OPCA, and only in 14.2% with SND, but was not found in LOCA patients (t test, p < 0.05). In patients with OPCA, the combination of gaze-evoked nystagmus, abnormalities of sinusoidal VOR and reduced OKN gain measurements was very frequent, while infrequent in both LOCA (Fisher's exact test, p < 0.05) and SND subjects (p < 0.01). SDS also showed abnormalities of the oculomotor system.     

The 3081/E Processor and Its on-Line Use

The 3081/E is a second generation emulator of a mainframe IBM. One of it's applications will be to form part of the data acquisition system of the upgraded Mark II detector for data taking at the SLAC linear collider. Since the processor does not have direct connections to I/O devices a FASTBUS interface will be provided to allow communication with both SLAC Scanner Processors (which are responsible for the accumulation of data at a crate level) and the experiment's VAX 8600 mainframe. The 3081/E's will supply a significant amount of on-line computing power to the experiment (a single 3081/E is equivalent to 4-5 VAX 11/780'S). A major advantage of the 3081/E is that program development can be done on an IBM mainframe (such as the one used for off-line analysis) which gives the programmer access to a full range of debugging tools. The processor's performance can be continually monitored by comparison of the results obtained using it to those given when the same program is run on an IBM computer.