Le codeur mpeg-2 AAC expliqué aux traiteurs de signaux

The MPEG- 2 Advanced Audio Coder is the latest issue of the MPEG audio encoders/decoders family, whose most popular version is known as MP3. It gathers many of the latest highly efficient sound compression techniques in a quite classically structured coder. The main part is based on a Discrete Cosine Transform with variable resolution. The output from this filterbank is compressed by the combination of an adaptive bit allocation module, according to frequency subbands, and a set of noiseless Huffman codebooks. Bit allocation is controlled by a psychoa-coustic model which determines an audibility threshold for signal distortion in the frequency domain. This article intends to explain the ISO standard without replacing it, and also to be a general introduction to perceptual audio coding.     

Diurnal cortisol secretion and 2-year changes in older adults' physical symptoms: The moderating roles of negative affect and sleep.

Objective: This study examined whether the association between cortisol secretion and changes in physical health symptoms would depend on other factors in a person's life. The authors expected that physical health effects would emerge particularly when cortisol disturbances co-occur in the context of high levels of trait negative affect or poor sleep. Design: Physical symptoms, diurnal cortisol secretion, affective tendencies, and sleep efficiency were assessed in a 2-yr longitudinal study of 184 older adults. Main Outcome Measure: Two-year changes in physical symptoms. Results: High cortisol levels were associated with increases in physical symptoms, but only among participants who experienced high negative affect and poor sleep. Conclusion: Elevated levels of cortisol secretion contribute to older adults' physical symptoms if they co-occur in the context of other emotional and behavioral problems. By contrast, cortisol disturbances may not influence physical symptoms among people who are emotionally well or engage in efficient sleep behaviors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Formulation, characterization, and efficacy of an adenosine-containing dissolvable film for a localized anti-wrinkle effect

A water-dissolvable film was developed to topically deliver adenosine for a localized anti-wrinkle effect. The polymers used to produce the film were cellulose derivatives. An aqueous mixture of the film components was made, coated on a liner, and then dried to form a solid film. No preservatives were added and the film was shown to be stable over time. The film quickly dissolves in water to form a uniform layer at the surface of the skin, as shown by scanning electron microscopy. The film layer can still be visualized on the wrinkle 6 h after being applied on the skin. A randomized, placebo-controlled, investigator-blind study was conducted in female volunteers to assess the efficacy of the 1% adenosine-containing dissolvable film. After 3 weeks and 8 weeks, a twice daily application led to a significant decrease in the skin roughness parameters as observed using fast optical in vivo topometry (FOITS). These results demonstrate that water-dissolvable films may be used as novel, preservative-free, cosmetic delivery systems.     

Incorporation of Galvanic Waste (Cr, Ni, Cu, Zn, Pb) in a Soda–Lime–Borosilicate Glass

In the present investigation, a glassing process for galvanic waste (GW) incorporation with a high chemical stability is presented. Glasses with up to 50 wt% of galvanic solid waste by modifications in the basic composition of soda–lime–borosilicate glasses were prepared. After fusing at temperatures up to 1300°C, the glasses were characterized by inductively coupled plasma, scanning electron microscopy/energy-dispersive X-ray spectroscopy, high-temperature microscopy, transmission and reflected light microscopy, nuclear magnetic resonance, X-ray photoelectron spectroscopy, and X-ray diffraction methods. The chemical stability was evaluated by hydrolytic attack assays. Glasses containing up to 40 wt% of GW with a very high chemical stability, similar to bottle glasses, were obtained.     

Effects of polyvinylchloride films and edible starch coatings on quality aspects of refrigerated Brussels sprouts

To extend shelf life, the effects of polyvinylchloride film (PVC) and edible coatings on quality aspects of refrigerated Brussels sprouts were studied. Starch-based coatings were formulated using glycerol (G), sorbitol (S) or glycerol plus sunflower oil (O). Sprouts so treated as well as uncoated ones were placed on expanded polystyrene trays. Combinations of PVC and coatings (treatments named G-PVC, S-PVC and O-PVC) were also tested. Uncovered trays were maintained as controls. All packages were stored at 0 °C for 42 days and samples were removed every 14 days to determine commercial acceptability, weight loss, surface colour (of sprouts’ heads and bases) and texture. Sprouts in all treatments maintained optimum quality conditions over the first 14 days. At the end of storage, browning of cut zones and losses in weight and firmness were minimised in PVC-packaged sprouts, particularly in G-PVC. Therefore, PVC and G-PVC treatments were selected to evaluate some nutritional quality components. Ascorbic acid and total flavonoid contents remained almost constant while radical scavenging activity increased after 42 days of storage. Thus, PVC and G-PVC treatments showed the best performance for long-term refrigerated storage of Brussels sprouts.     

Fluorescence histochemical techniques for catecholamines as tools in neurobiology

Formaldehyde-induced and glyoxylic-acid-induced fluorescence histochemistry permits the tissue localization of catecholamines in the central nervous system (CNS) and peripheral nervous system (PNS), and in culture. Counterstains such as ethidium bromide provide excellent background identification of specific innervated regions in both the CNS and the periphery. Use of fluorescence histochemistry with immunocytochemistry can elucidate catecholamine-peptide relationships. Gelatin-ink perfusion used with fluorescence histochemistry permits the investigation of neuro-vascular relationships and documentation of vascular and parenchymal compartmentation of innervation. Combined use of fluorescence histochemistry and retrograde tracing methods demonstrates the specific cellular sources of innervation of target regions. Micropunch neurochemical analysis provides quantitative data for correlation with fluorescence histochemistry within a target region of innervation, and micro-spectrofluorometric analysis provides a semi-quantitative evaluation of the amount of fluorophore within a target region or within specific subcellular compartments such as the cell body or terminals.     

Pore-scale derivation of the Ergun equation to enhance its adaptability and generalization

The empirical nature of the well-known Ergun equation for prediction of the permeability of granular materials inhibits the straightforward generalization to other geometries of the pore space and non-Newtonian effects of traversing fluids. In this paper the results are discussed of a pore-scale model that can be regarded as qualitative and quantitative proof of the Ergun equation. The pore-scale model has superior adaptive capabilities and also allows investigation of the porosity dependence of the empirical coefficients of the Ergun equation. Some advantages, based on physical grounds, of the pore-scale model are outlined.