Startle amplitude and fear in an acoustic startle paradigm: Lesions to the brachium of the inferior colliculus or the lateral tegmental tract.

In 2 Experiments, startle amplitude and startle stimulus-induced freezing (an index of fear) were measured in an acoustic startle response (ASR) paradigm in rats. Lesions to lateral tegmental tract (LTG), a pathway medial to brachium of the inferior colllciulus (BIC), significantly decreased freezing and produced a persistent 5-fold increase in ASR amplitude compared with sham-operated controls. Lesions to BIC increased both ASR amplitude (2-fold) and freezing. Neither BIC not LTG lesions affected startle amplitude when startle was elicited by a brief footshock stimulus. Characteristics of the lesion effects were tested with manipulations of interstimulus interval, stimulus intensity, and prepulse inhibition. The data suggest (a) an ascending pathway medial to BIC that carries the fear-inducing dimensions of an acoustic stimulus and (b) a descending pathway that provides tonic inhibition of the sensory input to the ASR circuitry. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Determination of UO2(s) dissolution rates in a hydrogen peroxide medium as a function of pressure and temperature

A continuously stirred flow-through tank reactor has been developed and successfully used to determine rates of dissolution of powdered samples of uranium dioxide at pressure and temperature conditions above the ambient values. The experiments have been performed in a temperature range from 20 to 50 °C and a total hydraulic pressure ranging from 1 to 32 bar. Experiments have been performed in a test solution containing 10⁻⁴ mol/L of H₂O₂, 3 × 10⁻³ mol/L of NaHCO₃ and, finally, NaClO₄ to get a constant ionic strength of 0.1 mol/L. An empirical equation has been obtained that describes the results in the experimental range studied and gives a good concordance with values obtained at ambient conditions in other works. On the other hand, scanning electron microscopy (SEM) has shown that the solid surface has homogeneously reacted, and, in addition, no secondary solid phase has been formed on the UO₂ surface.     

On the use of the geometric mean approximation in estimating the effective hygro-elastic behavior of fiber-reinforced composites

A geometric averaging is employed in a scale transition model dedicated to determining the effective hygro-elastic macroscopic properties of a fiber-reinforced composites from the properties of its constituents (i.e., the fiber and the matrix), for the first time. Calculations of macroscopic and local stresses due to hygroscopic loads are also carried out. Numerical computations performed according to the geometric mean are compared to the corresponding predictions given by the arithmetic average, classically used in the field of micro-mechanical modeling.     

Atypical depression: Enhanced right hemispheric dominance for perceiving emotional chimeric faces.

Two studies compared hemispatial bias for perceiving chimeric faces in patients having either atypical or typical depression and healthy controls. A total of 245 patients having major depressive disorder (MDD) or dysthymia (164 with atypical features) and 115 controls were tested on the Chimeric Faces Test. Atypical depression differed from typical depression and controls in showing abnormally large right hemisphere bias. This was present in patients having either MDD or dysthymia and was not related to anxiety, physical anhedonia, or vegetative symptoms. In contrast, patients having MDD with melancholia showed essentially no right hemisphere bias. This is further evidence that atypical depression is a biologically distinct subtype and underscores the importance of this diagnostic distinction for neurophysiologic studies. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Gender-sensitive recommendations for assessment and treatment of depression in men.

Psychologists increasingly recognize depression as a serious, albeit often undiagnosed, condition in men. In fact, undiagnosed and untreated depression in men may be one reason why many more men than women commit suicide. However, because of cultural conditioning that discourages expression of depressed mood in men, assessment as well as treatment of depression in men are sometimes difficult. Use of gender-sensitive assessment strategies and interventions will assure that more men will be identified and treated for depression. This article integrates scientific findings related to depression in men with specific gender-sensitive assessment and psychotherapeutic intervention strategies designed to enhance psychologists' skills in working with this significant problem in men. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Controlled growth of 1D and 2D ZnO nanostructures on 4H-SiC using Au catalyst

A perfect control of nanostructure growth is a prerequisite for the development of electronic and optoelectronic device/systems. In this article, we demonstrate the growth of various ZnO-derived nanostructures, including well-ordered arrays of high aspect ratio single crystalline nanowires with preferred growth direction along the [0001] axis, nanowalls, and hybrid nanowire-nanowall structures. The growths of the various ZnO nanostructures have been carried out on SiC substrates in a horizontal furnace, using Au thin film as catalyst. From experimental observations, we have ascribed the growth mechanisms of the different ZnO nanostructures to be a combination of catalytic-assisted and non-catalytic-assisted vapor–liquid-solid (VLS) processes. We have also found that the different ZnO nanoarchitectures'' material evolution is governed by a Zn cluster drift effects on the SiC surface mainly driven by growth temperature. Au thin film thickness, growth time, and temperature are the parameters to optimize in order to obtain the different ZnO nanoarchitectures.     

Large‐Scale X‐Ray Microtomography Analysis of Fiber Orientation in Weld Line of Short Glass Fiber Reinforced Thermoplastic and Related Elasticity Behavior

Large‐scale X‐ray microcomputed tomography (μ‐CT) is used to investigate microstructural features of weld lines in a short glass fiber reinforced polymer. The main originality of this work is related to the evaluation of local structural and mechanical characteristics in zones of unmastered heterogeneities. Complete and incomplete injection molded plates are considered to investigate weld lines with and without process‐induced porosity. Using a helical scanning trajectory, the full 3D microstructure is obtained at centimetric scale to cover a large zone including first contact between colliding fronts at a voxel size of 3 μm. Microstructure analyses show that weld line area is ill‐ordered at the fiber and structure length scales. Near the first contact point, fiber orientations show the signature of vortexes, which mark the presence of repulsive forces. The presence of micrometric porosity is only confirmed in incomplete plates. μ‐CT images are used as inputs to create a full‐scale finite element model for assessing strain localization. Predicted principal strains are compared to digital image correlation measurements performed during uniaxial tensile tests. Full‐scale modeling combined to 3D high‐resolution imaging proves high potential to correlate local fiber heterogeneities with strain localization effects.

     

A Photorhabdus Natural Product Inhibits Insect Juvenile Hormone Epoxide Hydrolase

Simple urea compounds (“phurealipids”) have been identified from the entomopathogenic bacterium Photorhabdus luminescens, and their biosynthesis was elucidated. Very similar analogues of these compounds have been previously developed as inhibitors of juvenile hormone epoxide hydrolase (JHEH), a key enzyme in insect development and growth. Phurealipids also inhibit JHEH, and therefore phurealipids might contribute to bacterial virulence.     

SEC‐MALS study of dynamic structuring of natural rubber: Comparative study of two Hevea brasiliensis genotypes

The dynamic structuring of natural rubber (NR) was studied selecting two specific Hevea brasiliensis genotypes (RRIM600 and PB235) to prepare model samples. The mesostructure (macromolecular structure + aggregates or gel) of NR samples was studied by SEC‐MALS. The NR samples were analyzed after (i) slow structuring (18 months' storage at room temperature) and (ii) fast structuring (stored for 24 h on P₂O₅ at 60°C). This study showed that the macromolecular structure, especially M_n, and the total gel rates were dramatically modified after fast structuring. For genotype RRIM600, the aggregates formed during fast structuring were essentially macroaggregates, whereas for genotype PB235 mostly microaggregates were formed. These results indicate that the dynamic structuring of NR is dependent on genotype. Depending on the genotype, for extreme conditions (fast structuring), it can be assumed there was percolation between elementary bricks, probably microaggregates, or no percolation. Although the mechanisms of dynamic structuring are quite complex and should be multifactors dependent, on the basis of our results, the degree of percolation seems to be partly dependent on the quantity of short polyisoprene chains initially present in the NR samples. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Linear buckling analysis of thin-walled members combining the Generalised Beam Theory and the Finite Element Method

A finite element procedure to carry out linear buckling analysis of thin-walled members is developed on the basis of the existing Generalised Beam Theory (GBT) and constrained Finite Strip Method (cFSM). It allows designers to uncouple the buckling modes of a finite element model and, consequently, to calculate pure elastic buckling loads. The procedure can easily be applied to members with general boundary conditions subjected to compression or bending. The results obtained are rather accurate when compared to the values calculated via GBT and cFSM. As a consequence, it is demonstrated that linear buckling analyses can be performed with the Finite Element Method in a similar way as can be done with the existing GBT and cFSM procedures.