Dietary cholesterol impairs memory and memory increases brain cholesterol and sulfatide levels.

Cholesterol and sulfatides play many important roles in learning and memory. To date, our observations about the effects of cholesterol on learning have been assessed during response acquisition; that is, the learning of a new memory. Here, we report for the first time to our knowledge, on the effect of a cholesterol diet on a previously formed memory. Rabbits were given trace conditioning of the nictitating membrane response for 10 days, then fed a 2% cholesterol diet for 8 weeks, and then assessed for memory recall of the initially learned task. We show that dietary cholesterol had an adverse effect on memory recall. Second, we investigated whether dietary cholesterol caused an increase in brain cholesterol and sulfatide levels in four major brain structures (hippocampus, frontal lobe, brainstem, and cerebellum) using a technique for analyzing myelin and myelin-free fractions separately. Although our data confirm previous findings that dietary cholesterol does not directly affect cholesterol and establish that it does not affect sulfatide levels in the brain, these levels did increase rather significantly in the hippocampus and frontal lobe as a function of learning and memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Tools and techniques for product design

For product designers, tools and techniques are essential in driving the design cycle. Nevertheless, their employment usually is implicit, while passing over e.g. the design and project environments empowering their adequate use. This publication presents an overview of approaches in structuring and using tools/techniques, based on the effectuation of creativity and decision-making in the design environment. In elaborating on characteristics of tools/techniques and ensuing ways of selecting them, the designer's portfolio of tools/techniques is characterised. Representative problems of tool/technique usage are depicted and contextualised by illustrating their industrial application. Prospects for future developments are also reviewed.     

Inactivation of the central nucleus of the amygdala abolishes conditioning-specific reflex modification of the rabbit (Oryctolagus cuniculus) nictitating membrane response and delays classical conditioning.

The central nucleus (CE) of the amygdala has been gaining attention for its importance in the plasticity underlying conditioned emotional responding. Already known for its role in nictitating membrane response (NMR) reflex facilitation, the CE may also be involved in conditioning-specific reflex modification (CRM)--changes in the NMR to the unconditioned stimulus (US) when tested in the absence of the conditioned stimulus following classical conditioning. To examine the CE's role in acquisition and/or expression of CRM, the authors temporarily inactivated the CE of rabbits (Oryctolagus cuniculus) with muscimol during NMR conditioning and/or during US testing. Results show that CRM was abolished by inactivation during US testing but intact following inactivation during NMR conditioning, suggesting that the CE is involved in CRM expression. Also, inactivation during conditioning delayed the development of conditioned NMRs. These findings show that the CE may act as an output center for expression of emotional responding in one situation (CRM) but is involved in facilitating plasticity in another (NMR conditioning). The authors propose that analysis of CRM may be an important corollary to current models for the treatment of posttraumatic stress disorder. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Low-Temperature Aging of Y-TZP Ceramics

The isothermal tetragonal-to-monoclinic transformation of a 3Y-TZP ceramic is investigated from 70° to 130°C in water and in steam by X-ray diffraction and optical interferometer techniques. Aging kinetics followed by X-ray diffraction are fitted by the Mehl-Avrami-Johnson law, suggesting nucleation and growth to be the key mechanisms for transformation. Optical interferometer observations of highly polished samples effectively reveal a nucleation and growth micromechanism for tetragonal-to-monoclinic transformation. A model based on surface change analysis is developed that fits closely to the X-ray diffraction results.     

Implantation effects of low energy H and D ions in germanium at −120 °C and room temperature

Germanium was implanted with 5 keV H and D ions at −120 °C or room temperature and thermally annealed in several steps. The samples were analysed at various stages by atomic force microscopy, ion channeling and Raman spectroscopy of Ge-H/D local vibration modes. The results are discussed in comparison with those in the well studied silicon. In general, the evolution of the different types of defects, in germanium at a given temperature, tends to be similar to that of the corresponding defects in silicon at 100-300 °C higher temperature. However, the behaviour of the defects detected by ion channeling (interstitials, lattice distortions) often appears unrelated to the chemical evolution measured by Raman scattering and to the temperature and isotope dependence of blistering.     

Influence of the adjustable parameters of the DPD on the global and local dynamics of a polymer melt

We present DPD simulations of linear polyethylene melts with force fields derived from microscopic simulations using the concept of potential of mean force. We aim at simulating realistic short polymers from a qualitative and quantitative point of view. An interesting issue is then to know the influence of the adjustable parameters of the DPD: γ, the friction coefficient, and r_C, the cut-off radius, on the global and local dynamics of the polymer, i.e., the diffusion coefficient, D_CM, the end-to-end decorrelation time, τ_R and the Rouse times. By varying these two parameters, we investigate structural and dynamical properties for different polymeric systems at a given chain length. Although scaling laws typical of the Rouse model have been reproduced using this DPD method, we observe deviation from the Rouse theory for the local dynamics of certain systems. The dynamical properties of the polymer melt are defined simultaneously by γ and r_C. Therefore we combine these two parameters, introducing a new parameter, the effective friction coefficient, γ^eff.     

Practical application of the “turbid water” flag in ocean color imagery: Interference with sun-glint contaminated pixels in open ocean

A simple method to identify turbid, sediment-loaded, waters within satellite ocean color imageries was recently proposed (A. Morel and S. Bélanger, Remote Sensing of Environment, 102, (2006), 237-249). Systematic application of this method to the level-3 composites obtained from three ocean color sensors shows that the “turbid” flag is often raised in the open ocean, especially in the sub-tropical oligotrophic gyres, where turbidity is unlikely. In addition these flagged zones migrate with season, and clearly follow the sun declination course. The combination of low chlorophyll waters with a residual sun-glint is at the origin of this artifact. Simple approaches for eliminating such a misleading detection are proposed. The identification and elimination of the bias are also needed in particular for an unambiguous detection of the presence of calcite (coccolithophores) in open waters.     

Sub-pixel water temperature estimation from thermal-infrared imagery using vectorized lake features

Water skin temperature derived from thermal infrared satellite data are used in a wide variety of studies. Many of these studies would benefit from frequent, high spatial resolution (100 m pixels) thermal imagery but currently, at any given location, such data are only available every few weeks from spaceborne sensors such as ASTER. Lower spatial resolution (1 km pixels) thermal imagery is available multiple times per day at any given location, from several sensors such as MODIS on board both the AQUA and TERRA satellite platforms. In order to fully exploit lower spatial resolution imagery, a sub-pixel unmixing technique has been developed and tested at Quesnel Lake, British Columbia, Canada. This approach produces accurate, frequent high spatial resolution water skin temperature maps by exploiting a priori knowledge of water boundaries derived from vectorized water features. The pixel water-fraction maps are then input to a gradient descent algorithm to solve the mixed pixel ground leaving radiance equation for sub-pixel water temperature. Ground-leaving radiance is estimated from standard temperature and emissivity data products for pure pixels and a simple regression technique to estimate atmospheric effects. In this test case, MODIS 1 km thermal imagery was used along with 1:50,000 water features to create a high-resolution (100 m) water skin temperature map. This map is compared to a concurrent ASTER temperature image and found to be within 1 °C of the ASTER skin temperature 99% of the time. This is a considerable improvement over the 2.55 °C difference between the original MODIS product and ASTER image due to land temperature contamination. The algorithm is simple, effective, and unlocks a largely untapped resource for limnological and hydrological studies.     

Analyse de “microantennes” par une méthode temporelle

In this paper, a time domain analysis based on the resolutions of integral equations by the method of moments, is applied to the study of microstrip antennas. At first, the theory will be recalled with the different methods of calculation of antennas characteristics: input impedance, radiation pattern, as well as given approximations. Then, results will be presented and compared to those obtained with frequency methods.