A high-resolution all-digital pulse-width modulator architecture with a tunable delay element in CMOS

A design for an all-digital high-resolution pulse-width modulator (HRPWM) architecture is presented in this work. The architecture is based on a novel digitally controlled delay element that combines two different approaches, achieving a variable time interval up to 54 ps, and adjustable against process, voltage, and temperature (PVT) variations. The proposed system uses several delay elements with a counter-based digital pulse-width modulator (DPWM) in a hybrid configuration, which allows to obtain duty cycles with 18-bit resolution without using a high-frequency internal clock and maintaining a low power dissipation. The HRPWM was implemented in a standard low-cost 130-nm CMOS technology, together with a memory used to store the duty cycles, and a serial communication module. Post layout simulation results show good linearity between the control word and the duty cycle in all the range. The chip can be fine tuned to improve its performance using the calibration capabilities of the architecture. The analysis includes a comparison with another state-of-art HRPWMs showing the advantages of the proposed approach.     

TOTAL MERCURY DETERMINATION IN NAPHTHAS BY EITHER ATOMIC FLUORESCENCE OR ABSORPTION SPECTROSCOPY

ABSTRACT

Mercury determination in light hydrocarbon fractions and natural gas condensates, has long been an important issue in the oil industry. Mercury has to be monitored, because of the many problems encountered with this metal in reforming and processing. The main objective of this study was to develop a fast reliable methodology to quantify total mercury in naphtha fractions.

Since there is no certified standard analysis procedure for Hg in naphtha, two methodologies with different operating principles were implemented, namely: atomic fluorescence spectroscopy with thermal desorption (AFS-TD) and atomic absorption spectroscopy with electrothermal atomization (AAS-ETA). The statistical treatment applied was paired t-test (95% confidence level), which showed that both techniques are statistically equivalent.     

Potential Antibacterial Activity of Carvacrol-Loaded Poly(DL-lactide-co-glycolide) (PLGA) Nanoparticles against Microbial Biofilm

The ability to form biofilms contributes significantly to the pathogenesis of many microbial infections, including a variety of ocular diseases often associated with the biofilm formation on foreign materials. Carvacrol (Car.) is an important component of essential oils and recently has attracted much attention pursuant to its ability to promote microbial biofilm disruption. In the present study Car. has been encapsulated in poly(dl-lactide-co-glycolide (PLGA) nanocapsules in order to obtain a suitable drug delivery system that could represent a starting point for developing new therapeutic strategies against biofilm-associated infections, such as improving the drug effect by associating an antimicrobial agent with a biofilm viscoelasticity modifier.     

The relationship between multisensory integration and IQ in children.

It is well accepted that multisensory integration has a facilitative effect on perceptual and motor processes, evolutionarily enhancing the chance of survival of many species, including humans. Yet, there is limited understanding of the relationship between multisensory processes, environmental noise, and children's cognitive abilities. Thus, this study investigated the relationship between multisensory integration, auditory background noise, and the general intellectual abilities of school-age children (N = 88, mean age = 9 years, 7 months) using a simple audiovisual detection paradigm. We provide evidence that children with enhanced multisensory integration in quiet and noisy conditions are likely to score above average on the Full-Scale IQ of the Wechsler Intelligence Scale for Children—Fourth Edition (WISC–IV). Conversely, approximately 45% of tested children, with relatively low verbal and nonverbal intellectual abilities, showed reduced multisensory integration in either quiet or noise. Interestingly, approximately 20% of children showed improved multisensory integration abilities in the presence of auditory background noise. The findings of the present study suggest that stable and consistent multisensory integration in quiet and noisy environments is associated with the development of optimal general intellectual abilities. Further theoretical implications are discussed. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Melissopalynological origin determination and volatile composition analysis of Corsican “chestnut grove” honeys

Fifty Corsican “chestnut grove” honeys were certified by melissopalynological analysis. Castanea sativa was strongly overrepresented and was accompanied mainly by Rubus sp., Quercus ilex, Anthyllis hermanniae, Myrtus communis, Genista sp., Erica arborea, Cistus creticus, and Fraxinus ornus. Headspace solid-phase microextraction was performed to investigate the volatile composition of Corsican chestnut catkins and chestnut grove honeys. The main compounds of the chestnut catkins were acetophenone (21.5%), methyl salicylate (13.4%), nonanal (10.9%), and linalool (7.5%), whereas the major constituents of the honeys were 2-aminoacetophenone (11.4%), benzaldehyde (10.8%), acetophenone (7.0%), nonanoic acid (5.9%), octanoic acid (5.0%), and 3-furaldehyde (4.9%). By entering the aromatic intensity, the relative frequency of C. sativa, Rubus sp., and A. hermanniae pollens, and the physicochemical parameters as discriminate variables, principal component analysis (PCA) and cluster analysis (CA) showed that the distribution of Corsican “chestnut grove” honeys correlates with climatic events and/or honeybee foraging behaviours.     

Dipyridamole stress echocardiography for risk stratification in hypertensive patients with chest pain

BACKGROUND: The noninvasive prognostic assessment of coronary artery disease (CAD) in hypertensive patients represents an unresolved task to date. In this study, we investigated the value of dipyridamole stress echocardiography in risk stratification of hypertensive patients with chest pain and unknown CAD. METHODS AND RESULTS: Dipyridamole stress echocardiography was performed in 257 hypertensives (110 men; age, 63+/-9 years) complaining of chest pain and without a history of CAD. No major complications occurred. Four tests were interrupted prematurely because of side effects, with 98. 4% feasibility of test. A positive echocardiographic response was found in 72 patients (27 during the low-dose [0.56 mg/kg]). During the follow-up (32+/-18 months), 27 cardiac events occurred: 3 deaths, 8 infarctions, and 16 cases of unstable angina. Moreover, 27 patients underwent coronary revascularization. At multivariate analysis, the positive echocardiographic result (OR, 5.5; 95% CI, 1.4 to 16.6) was the only predictor of hard cardiac events (death, infarction). Considering spontaneous cardiac events (death, infarction, and unstable angina) as end points, the positive echocardiographic result (OR, 4.2; 95% CI, 1.8 to 9.6) and family history of CAD (OR, 4.2; 95% CI, 1.5 to 6. 9) were independently associated with prognosis. The 3-year survival rates for the negative and the positive populations were, respectively, 97% and 87% (P=0.0019) considering hard cardiac events and 96% and 74% (P=0.0000) considering spontaneous cardiac events. CONCLUSIONS: Dipyridamole stress echocardiography is safe, highly feasible, and effective in risk stratification of hypertensives with chest pain and unknown CAD. At present, it represents an attractive option for prognostic assessment of this clinically defined population.     

Use of a Reverberating Enclosure for Measurements of Radiated Power in the Microwave Range

A method using a reverberating enclosure for evaluating the radiation of an apparatus in the microwave range (1-18 GHz)is described. The physical performance of the reverberating enclosure has been analyzed by means of a sampling correlator. The method is particularly suitable for measurements of radiated interference from industrial, scientific, and medical (I.S.M.) equipment in terms of power, and to state their compliance with specified limits. Other important applications of the reverberating enclosure may include the measurement of average absorption coefficient of bulk or plate materials and of the behavior of the human body in an EM microwave field.     

Amino acid sequence, post-translational modifications, binding and labelling of porcine odorant-binding protein

An odorant-binding protein, migrating in SDS-PAGE with an apparent molecular weight of 22 kDa and an isoelectric point of 4.2, has been purified from pig nasal mucosa. Its complete amino acid sequence was determined by a combination of mass spectrometry and Edman degradation procedures. The protein consists of a single polypeptide chain of 157 amino acids, presenting at the N-terminus a pyroglutamic acid residue. The two cysteine residues, occurring in the primary structure at positions 63 and 155, are involved in an intramolecular disulphide bridge. Sequence comparison with other lipocalins revealed a good similarity with bovine odorant-binding protein, the only member of this class which does not contain disulphide bonds and of which the three-dimensional structure recently has been resolved. Nine out of the 1 6 residues lining the binding pocket in bovine OBP are conserved in the porcine protein, suggesting structural similarities in this region of the molecule. The synthesis of a fluorescent photoaffinity labelling agent and of two tin-containing thymol analogues is also described. These compounds together with other ligands were able to bind the protein as revealed by competitive binding experiments.     

The Gaussian Approximation to Homogeneous Bose Gas

We study low-lying excitations of a spinless homogeneous Bose gas with repulsive interaction at zero temperature in terms of the Gaussian mean field approximation. The dynamical equations of this approximation have been derived for small displacements from the static Hartree-Fock-Bogoliubov solution. We obtain a gapped continuous band of excitations above a discrete branch with phonon behavior at long wavelength regime. We also discuss the available forms of excitations and conclude that there are constraints on the first order deviations of the Gaussian approximation parameters and they are generated by an infinitesimal unitary transformation.     

Finite element minimization of curvature functionals with anisotropy

We consider the prescribed curvature problem including anisotropy effects. The functional setting inBV (Ω;{−1,1}) is convexified and regularized by strictly convex functionals which, in turn, are discretized by continuous piecewise linear finite elements. It is known that sequences of discrete minima converge to a continuous minimizer. We discuss an efficient implementation of the minimization procedure based on a constrained modified Newton algorithm. Several numerical examples illustrate performances of our algorithm. This work was partially supported by MURST (Progetto Nazionale “Analisi Numerica e Matematica Computazionale”) and CNR (IAN and Contracts 92.00833.01, 94.00139.01) of Italy.