évaluation du livre intitulé manuel de gérontologie sociale 2.

Reviews the book, Manuel de gérontologie sociiale 2 by Jean Carette (1992). The Handbook of Social Gerontology 2 constitutes a practical complement of volume 1 which related to the social aspects of ageing and the retirement. Volume 2 relates mainly to the social intervention whose objective is to support the action and the collective mobilization individuals and associations of retirements. Using a 30-year experiment with groups of retirees, either in preparation of retirement, or in the collective action, the author approaches a new ground in gerontology. He proposes a new approach--social gerontology, (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A new device for measuring the real area of contact of polymeric material by the perturbation of total internal reflection

An optical device has been developed to measure precisely and directly the real area of contact (RAC) between a glass prism and a machined polymeric surface. It is based on the perturbation of total internal reflection of a light beam in the region of contact between the two solid surfaces. The optical and electronic components of equipment intended for the measurement of the RAC, given in terms of percentage of the apparent surface of contact, were selected to provide improvements in the way of using this method and have permitted to reach a precision of about 1.5%, and a resolution of 0.05%, for finishes rougher than 1.0m centre line average roughness value (CLA). These components also ensure measurements with a calibration factor independent of the material considered and its colouration. The design concepts are outlined, and typical experimental results for a thermoplastic material are presented, which show a good performance of repeatability. The variation of RAC with normal load was investigated with a large range of surface roughness of polymeric specimens. The results are included, and show that the real area of contact varies as 0.88 power of the normal load, with a proportionality constant dependent on the roughness of the contacting polymer surface.     

Thioacidolysis of Lignin: Comparison with Acidolysis

Abstract

Arylglycerol-ether bonds of lignin samples or model compounds vera selectively cleaved by treatment with dioxane-ethanethiol (9/1, v/v) and 0.2 N HBF₄ etherate or 0.2 N BF₃ etherate at 100°C for four hour3. Monomers resulting from “thioacidolysis” were identified by gas chroraatography-mass spectrometry of their trimethylslly derivatives. Compared to acidolysls (dloxane-water, 0.2 N HCL, 100°C 4h), thioacidolysis yields less complex mixtures of monomers. The monomer yields for lignin thioacidolysis were also higher than for acidolysls. This increase was particularly evident for hardwood lignins.     

Structure and Reactivity of Spruce Mechanical Pulp Lignins Part I. Bleaching and Photoyellowing of in situ Lignins

This paper reports the structural investigation of a series of in situ spruce lignins in wood, thermomechanical pulp (TMP) and the corresponding bleached (BTMP) and photoyellowed (YBTMP) samples. This was achieved by using an original two-step degradative technique, thioacidolysis followed by Raney nickel desulfuration. The determination of thioacidolysis monomeric and dimeric products allowed an estimate of various lignin building units and interunit bonds, respectively. It was observed that the thermomechanical and bleaching treatments did not affect spruce lignin structure to an appreciable extent. On the contrary, the photoyellowing treatment caused marked structural changes in lignin, particularly when run in severe conditions. These changes were essentially a decrease in the amount of β-O-4 and β-1 interunit bonds and a relative increase in catechol units and in vanillin end-groups.     

Path‐following algorithms and experiments for an unmanned surface vehicle

This paper addresses the problem of path following in two‐dimensional space for underactuated unmanned surface vehicles (USVs), defining a set of guidance laws at the kinematic level. The proposed nonlinear Lyapunov‐based control law yields convergence of the path‐following error coordinates to zero. Furthermore, the introduction of a virtual controlled degree of freedom for the target to be followed on the path removes singularity behaviors present in other guidance algorithms proposed in the literature. Some heuristic approaches are then proposed to face the problem of speed of advance adaptation based on path curvature measurement and steering action prediction. Finally a set of experimental results of all the proposed guidance laws, carried out with the Charlie USV, demonstrates the feasibility of the proposed approach and the performance improvements, in terms of precision in following the reference path and transient reduction, obtained by introducing speed adaptation heuristics. © 2009 Wiley Periodicals, Inc.     

Short communication: Absorption of 2-hydroxy-4-methylthiobutanoate in dairy cows

The objective of this study was to measure net portal absorption of 2-hydroxy-4-methylthiobutanoate (HMTBA) in dairy cows. Four multicatheterized lactating cows were used in a cross-over design with 7-d experimental periods. They were fed every other hour a total mixed ration and received, in addition, twice a day, 12.5 or 25 g/meal of HMTBA. On the last day of treatment, net portal absorption of HMTBA was numerically greater after the 25-g compared with the 12.5-g bolus meal of HMTBA, and the amount absorbed relative to the dose ingested was unchanged between treatments averaging 11.2 ± 4.7% of the dose. This represents a minimum value of HMTBA availability because it does not take into account any HMTBA metabolized to Met by gut tissues (in sheep this amounted to another 5% of the dose). A rapid method to estimate net portal absorption based on temporal variations of the peripheral plasma HMTBA concentrations following the HMTBA meal is also presented. Based on the good relationship (concordance correlation coefficient = 0.97) observed between direct measurements and estimations, this simplified approach offers a reasonable approach to assess HMTBA absorption under different feeding situations.     

Milk protein synthesis as a function of amino acid supply

Most prediction schemes of milk protein secretion overestimate milk protein yield from dairy cows at high protein intakes, thereby overestimating milk protein yield response to protein supplementation. This study was conducted to determine factors contributing to such an overestimation. Using published studies, a database was constructed that was limited to amino acid (AA) infusion studies, as then only the digestible amino acid of dietary origin needed to be estimated, whereas the amount infused was known exactly, thereby reducing the dependence on estimated values. Although milk protein yield was positively related with total energy supply, and both digestible duodenal supply and infused AA, in this database there was no relationship between milk protein yield response above control treatments and the nutrient status of the cows (energy or protein). Total milk protein yield was defined as a function of individual AA supply, using a segmented-linear and a logistic model to obtain estimates of the efficiency of conversion of AA into milk protein. Except for Lys and Met supply, the segmented-linear model yielded lower root mean square error and better correlation, but both models were similar in their reliability. For both models, the estimated efficiency of conversion of AA to milk differed among AA. Estimations of the ideal profile of AA for lactating dairy cows were similar between models, with requirements for Lys and Met in line with 2001 National Research Council recommendations. The major difference is that the segmented-linear model yields a constant efficiency of conversion of an AA until requirements are met, with zero efficiency beyond this point. The logistic model allows for an estimation of the decreasing marginal efficiency of conversion of AA as the supply approaches the requirements. The use of variable efficiency factors should improve our ability to predict protein yield in response to supplemental protein.     

EBIC-guidelines for management of severe head injury in adults. European Brain Injury Consortium

Guidelines for the management of severe head injury in adults as evolved by the European Brain Injury Consortium are presented and discussed. The importance of preventing and treating secondary insults is emphasized and the principles on which treatment is based are reviewed. Guidelines presented are of a pragmatic nature, based on consensus and expert opinion, covering the treatment from accident site to intensive care unit. Specific aspects pertaining to the conduct of clinical trials in head injury are highlighted. The adopted approach is further discussed in relation to other approaches to the development of guidelines, such as evidence based analysis.