L'observation des processus de groupe: difficultés méthodologiques et perspectives.

Discusses problems involved in collecting data based on observation of small groups. The example of a study of manifestations of cooperation in groups of preschoolers (aged 21–57 mo) is used for illustration. Statistical treatment of observation data and global analysis of data are considered. (English abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Routing and resource optimization in service overlay networks

Service Overlay Networks (SONs) create a virtual topology on top of the Internet and provide end-to-end quality of service guarantees without requiring support by the underlying network.The optimization of the resources utilized by an SON is a fundamental issue for an overlay operator owing to the costs involved and the need to satisfy user requirements. Careful decisions are necessary to provide enough capacity to overlay links, to route traffic, to assign users to access nodes and to deploy overlay nodes.In this paper, we propose two mathematical programming models for the user assignment problem, the traffic routing optimization and the dimensioning of the capacity reserved on overlay links in SONs. The first model minimizes the SON installation cost while providing full access to all users. The second model maximizes the SON profit by selecting which users to serve, based on the expected gain, and taking into consideration budget constraints of the SON operator. Moreover, we extend these models to include the optimization of the number and position of overlay nodes.We provide the optimal solutions of the proposed SON design formulations on a set of realistic-size instances and discuss the effect of different parameters on the characteristics of the planned networks. Numerical results show that the proposed approach is able to solve the problem to the optimum even for large-scale networks.     

Seipin Deficiency as a Model of Severe Adipocyte Dysfunction: Lessons from Rodent Models and Teaching for Human Disease

Obesity prevalence is increasing worldwide, leading to cardiometabolic morbidities. Adipocyte dysfunction, impairing white adipose tissue (WAT) expandability and metabolic flexibility, is central in the development of obesity-related metabolic complications. Rare syndromes of lipodystrophy characterized by an extreme paucity of functional adipose tissue should be considered as primary adipocyte dysfunction diseases. Berardinelli-Seip congenital lipodystrophy (BSCL) is the most severe form with a near absence of WAT associated with cardiometabolic complications such as insulin resistance, liver steatosis, dyslipidemia, and cardiomyopathy. Twenty years ago, mutations in the BSCL2 gene have been identified as the cause of BSCL in human. BSCL2 encodes seipin, an endoplasmic reticulum (ER) anchored protein whose function was unknown back then. Studies of seipin knockout mice or rats demonstrated how seipin deficiency leads to severe lipodystrophy and to cardiometabolic complications. At the cellular levels, seipin is organized in multimers that are particularly enriched at ER/lipid droplet and ER/mitochondria contact sites. Seipin deficiency impairs both adipocyte differentiation and mature adipocyte maintenance. Experiments using adipose tissue transplantation in seipin knockout mice and tissue-specific deletion of seipin have provided a large body of evidence that liver steatosis, cardiomyopathy, and renal injury, classical diabetic complications, are all consequences of lipodystrophy. Rare adipocyte dysfunctions such as in BSCL are the key paradigm to unravel the pathways that control adipocyte homeostasis. The knowledge gathered through the study of these pathologies may bring new strategies to maintain and improve adipose tissue expandability.     

Object recognition versus object discrimination: Comparison between human infants and infant monkeys.

Human infants (aged 12–32 mo old) and adults learned a delayed nonmatching-to-sample (DNMS) task and single- and multiple-pair discrimination tasks using nonverbal procedures previously used with monkeys. Infants learned discriminations rapidly and at a young age (12 mo), but they required prolonged training and maturation before learning the DNMS task. Adults learned all tasks rapidly. After learning the DNMS task to criterion, memory performance declined systematically in an inverse relation to age. The dissociation in ability of infants on the DNMS vs discrimination tasks closely resembles the dissociation previously reported with infant monkeys (J. Bachevalier & M. Mishkin, 1984). Results from both infant humans and monkeys support a neurocognitive maturational model. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Age and sex differences in the effects of selective temporal lobe lesion on the formation of visual discrimination habits in rhesus monkeys (Macaca mulatta).

Three-month-old infant monkeys with neonatal ablations of either cortical area TE or the amygdala and hippocampus and age-matched normal infants were trained in a concurrent object discrimination task with 24-hr intertrial intervals. Neonatal area TE lesions yielded a transient deficit in visual habit formation, present in the female monkeys only, whereas the same lesions in adult monkeys yielded a severe and long-lasting deficit in both males and females. Although pointing to a greater neural compensation for the early loss as compared with the later loss of cortical area TE, the results also corroborate a recent suggestion (J. Bachevalier et al; see record 1990-03600-001) that, at 3 mo of age, area TE is more fully functional in females than in males. Neither early nor late amygdalohippocampal lesions impaired the ability to form visual discrimination habits, strengthening the proposal that the habit system uses a corticononlimbic circuit. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Soft,Implantable Bioelectronic Interfaces for Translational Research

The convergence of materials science, electronics, and biology, namely bioelectronic interfaces, leads novel and precise communication with biological tissue, particularly with the nervous system. However, the translation of lab-based innovation toward clinical use calls for further advances in materials, manufacturing and characterization paradigms, and design rules. Herein, a translational framework engineered to accelerate the deployment of microfabricated interfaces for translational research is proposed and applied to the soft neurotechnology called electronic dura mater, e-dura. Anatomy, implant function, and surgical procedure guide the system design. A high-yield, silicone-on-silicon wafer process is developed to ensure reproducible characteristics of the electrodes. A biomimetic multimodal platform that replicates surgical insertion in an anatomy-based model applies physiological movement, emulates therapeutic use of the electrodes, and enables advanced validation and rapid optimization in vitro of the implants. Functionality of scaled e-dura is confirmed in nonhuman primates, where epidural neuromodulation of the spinal cord activates selective groups of muscles in the upper limbs with unmet precision. Performance stability is controlled over 6 weeks in vivo. The synergistic steps of design, fabrication, and biomimetic in vitro validation and in vivo evaluation in translational animal models are of general applicability and answer needs in multiple bioelectronic designs and medical technologies.     

élaboration et validation d'un instrument de mesure de la conscience phonologique.

This study describes the steps in developing and validating a French-language instrument to measure phonological awareness. The selected task involves ranking from a list of 4 words presented orally. Ss must choose the word that begins differently than the others. To decrease the mnestic difficulty of the test, illustrations accompany the words. Two pre-experiments using a bank of 20 items led to preparation of a final version of the phonological awareness test, which consists of 10 items. The validity and reliability of this version were assessed using 57 pre-schoolers and 60 kindergartners. In terms of validity and reliability, the psychometric features of the test were deemed satisfactory for the kindergarten students but deficient for the pre-schoolers. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Two ways of synthesis of polymer networks based on diglycidyl ether of bisphenol A,bisphenol A,and sulfanilamide: Kinetics study

The kinetics of reactions of ternary systems based on bisphenol A diglycidyl ether, bisphenol A, and a sulfanilamide curing agent were investigated using HPLC, during two different synthesis paths. The influence of tetrabutylphosphonium tetrafluoroborate as a catalyst for the epoxy–phenol reaction was studied. For the same initial composition, polymers differing by the crosslink point distribution and the chain length between crosslinks were synthesized. Different solid‐state behavior is expected in these two categories of networks. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 580–591, 2001     

Effects of crosslink density on mechanical properties of high glass transition temperature polycyanurate networks

Polycyanurate networks of different architecture were synthesized using different curing cycles. Networks with a variable extent of reaction were obtained; the small variation of the cyanate conversion (0.8 to 1) corresponds to a large variation of glass transition temperature (150–290°C) and crosslink density. The mechanical behavior at small and large deformations and the fracture toughness were examined at room temperature and related to the network structural parameters. To explain the puzzling variation of the yield stress and yield strain with the cyanate conversion, recovery experiments were conducted to discriminate anelastic deformation from plastic deformation. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 2471–2479, 1997     

Effects of selective neonatal hippocampal lesions on tests of object and spatial recognition memory in monkeys.

Earlier studies in monkeys have reported mild impairment in recognition memory after nonselective neonatal hippocampal lesions. To assess whether the memory impairment could have resulted from damage to cortical areas adjacent to the hippocampus, we tested adult monkeys with neonatal focal hippocampal lesions and sham-operated controls in three recognition tasks: delayed nonmatching-to-sample, object memory span, and spatial memory span. Further, to rule out that normal performance on these tasks may relate to functional sparing following neonatal hippocampal lesions, we tested adult monkeys that had received the same focal hippocampal lesions in adulthood and their controls in the same three memory tasks. Both early and late onset focal hippocampal damage did not alter performance on any of the three tasks, suggesting that damage to cortical areas adjacent to the hippocampus was likely responsible for the recognition impairment reported by the earlier studies. In addition, given that animals with early and late onset hippocampal lesions showed object and spatial recognition impairment when tested in a visual paired comparison task, the data suggest that not all object and spatial recognition tasks are solved by hippocampal-dependent memory processes. The current data may not only help explain the neural substrate for the partial recognition memory impairment reported in cases of developmental amnesia, but they are also clinically relevant given that the object and spatial memory tasks used in monkeys are often translated to investigate memory functions in several populations of human infants and children in which dysfunction of the hippocampus is suspected. (PsycINFO Database Record (c) 2011 APA, all rights reserved)