Twin mirrors for laser interferometric gravitational-wave detectors

Gravitational-wave detectors such as Virgo and the laser interferometric gravitational-wave observatory (LIGO) use a long-baseline Michelson interferometer with Fabry-Perot cavities in the arms to search for gravitational waves. The symmetry between the two Fabry-Perot cavities is crucial to reduce the interferometer's sensitivity to the laser amplitude and frequency noise. To this purpose, the transmittance of the mirrors in both cavities should be as close as possible. This paper describes the realization and the characterization of the first twin large low-loss mirrors with transmissions differing by less than 0.01%.     

Inhibition of neuronal (type 1) nitric oxide synthase prevents hyperaemia and hippocampal lesions resulting from kainate-induced seizures

The possible roles for nitric oxide produced by neurons in epileptic conditions have been investigated from two different aspects: microcirculation and delayed damage. Our aim was to determine whether the selective inhibition of neuronal (type 1) nitric oxide synthase by 7-nitroindazole, during seizures induced by systemic kainate, modifies hippocampal blood flow and oxygen supply and influences the subsequent hippocampal damage. Experiments were performed in conscious Wistar rats whose electroencephalogram was recorded. 7-Nitroindazole (25 mg/kg, i.p.) or its vehicle was injected 30 min before kainate administration (10 mg/kg, i.p.) and then twice at 1-h intervals. Kainate triggered typical limbic seizures evolving into status epilepticus, identified by uninterrupted electroencephalographic spike activity. The seizures were stopped by diazepam (5 mg/kg, i.p.) after 1 h of status epilepticus. Three types of experiments were performed in vehicle- and 7-nitroindazole-treated rats. (1) Hippocampal nitric oxide synthase activity was measured under basal conditions, at 1 h after the onset of the status epilepticus and at 24 h after its termination (n = 4-6 per group). (2) Hippocampal blood flow and tissue partial pressure of oxygen were measured simultaneously by mass spectrometry for the whole duration of the experiment, while systemic variables and body temperature were monitored (n = 6 per group). (3) Hippocampal damage was revealed by Cresyl Violet staining and evaluated with a lesion score seven days after status epilepticus (n = 12 per group). Hippocampal nitric oxide synthase activity was not significantly modified during status epilepticus or the following day in vehicle-treated rats. In contrast, it was inhibited by 57% in 7-nitroindazole-treated rats, both in basal conditions and after 1 h of status epilepticus, but was not different from its basal level 24 h later. 7-Nitroindazole significantly decreased basal hippocampal blood flow and tissue partial pressure in oxygen by 30% and 35%, respectively without affecting any systemic or thermal variable. During status epilepticus, 7-nitroindazole significantly reduced the increase in hippocampal blood flow by 70% and prevented any increase in the tissue partial pressure of oxygen. Seven days later, the hippocampal damage in the CA1 and CA3 layers was significantly less in 7-nitroindazole-treated rats than in vehicle-treated rats. These results indicate that the inhibition of neuronal nitric oxide synthase by 7-nitroindazole protects neurons from seizure-induced toxicity despite reducing blood flow and oxygen supply to the hippocampus.     

Effect of divergent selection for immune responsiveness and of major histocompatibility complex on resistance to Marek's disease in chickens

Lines of chickens selected for nine generations for high (H) or low (L) antibody response to SRBC, a randombred control (C) line, and an F1 cross between H and L lines were challenged for resistance to Marek's disease (MD). Hens only were challenged at day-old by contact with virulent MD Strain K. Birds were serologically typed for MHC erythrocyte antigens. Chicks from the L and H lines died earlier and later, respectively, than the C chicks, whereas time of death did not differ between F1 birds and the L chicks. Mortality in the L line (70.1%) was higher than in the C line (42.8%), but mortality in the H line (40.9%) was not lower than in the C line or the F1 cross (47.5%). Effects of MHC genotypes and haplotypes on mortality from MD were estimated within lines with a logistic regression model. Effect of MHC was moderate in the H line (P < .10) and highly significant in the C line (P < .005). Effects of MHC genotypes were similar in the H and C line but differed in the L and F1. Heritability of mortality from MD estimated with a threshold model including relationships between individuals was .40 when all lines were grouped together, whereas heritability estimated for each line separately was .45, .51, and .78 in the H, C, and L lines, respectively. Correlations between estimated breeding values for antibody response to SRBC and mortality from MD varied between lines and sexes. Correlations also were affected by whether or not the MHC effect was taken into account.     

Le développement de la notion de vitesse relative.

Administered a modified version of a Piagetian test on the concept of relative velocity (including questions on the duration of relative displacements) to 96 children placed in age groups of 7, 9, 11, and 13 yr. It was found that (a) the developmental stages of the concept were comparable to those observed by Piaget except for formal operations which seem to evolve later; (b) the combination of 2 movements of same direction but unequal velocity is more difficult to synthesize than any other; (c) success on the problem of durations is not a prerequisite of at least partial success on the problem of velocities; and (d) complete success on the problem of velocities is not necessarily verbalized in spatio-temporal terms. To explain the difficulty observed in synthesizing velocities, the importance of the instructions (e.g., specifying the speed of each mobile) and of changes in the spatial order of the mobiles was emphasized. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Le r?le du surplombement dans l'estimation perceptive des longueurs de deux horizontales a extrémités decalées.

Asked a total of 84 children and adults in 4 age groups (means = 5.11, 7.8, 9.8, 11.5, and 24.4 yrs) to match, by the method of adjustment, the lengths of 2 horizontal lines staggered so as to form 2 sides of a parallelogram under 2 main conditions (variable over the standard or standard over the variable) and a control condition (variable and standard in prolongation). Results show that the variable was generally overestimated, this overestimation did not differ significantly from 1 condition to another, and this overestimation decreased significantly with age. Results suggest that this systematic error would not be attributed to the top positioning but rather to the movement of the variable, which would be a source of overestimation by drawing the relative frequency of S's perceptive centrations. The decrement of the error with age could be explained by the development of perceptual activity, allowing a more balanced centration on the standard and the variable. (French abstract) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Editorial.

Discusses editorial changes in the Canadian Journal of Psychology, which include a slight reduction in the number of articles published. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Relations entre la notion et la perception de la vitesse relative chez l'enfant.

Administered 2 tasks bearing on the perception and concept of relative velocity to 7-, 9-, 11-, and 13-yr-old children (24 at each age level). The perceptual task presented an illusion created by the movement of a target on a moving background, while the conceptual task was a modified version of Piaget's technique. In each task the 2 movements involved were either in the same (MS) or in the opposite direction. It was found that the illusion appeared earlier than the corresponding concept under the MS condition. The possibility of a retroactive effect of the concept on the percept is suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ionic implantation at low energy: application to the shallow junction accomplishment and surface functionalization

The proposed work deals with rapid thermal processing of ionic boron (¹¹B⁺) and boron difluoride (BF₂⁺), implanted in phosphorusdoped Cz-(100) silicon substrates through protecting oxide films, under different technological parameters. After implantation, the samples were rapidly thermally annealed at temperatures ranging from 900 to 1100 °C, in argon ambient gas, for different annealing durations. The rapid thermal annealings (RTAs) are carried out also, for some samples, after oxide mask removal. The total boron, fluorine as well as oxygen concentrations versus depth profiles, before and after annealing steps, in the SiO₂/Cz-(100) silicon systems were determined using secondary ion mass spectrometry (SIMS). Using a background concentration, the junction depth in the substrate has been investigated under different annealing experimental conditions. The kinetic diffusion process of implanted boron into oxide and monocrystalline silicon during rapid thermal treatments has also been investigated. The reported results show that boron diffusion in the BF₂⁺ case is widely reduced during rapid thermal treatments. Discussions of this are based on the effect of both knocked-on oxygen and fluorine on the boron diffusion kinetics.