Tuning the crystal structure and optical properties of selective area grown InGaAs nanowires

Catalyst-free InGaAs nanowires grown by selective area epitaxy are promising building blocks for future optoelectronic devices in the infrared spectral region.D...     

Verification of distributed systems with local�Cglobal predicates

This paper describes a methodology for developing and verifying a class of distributed systems in which the state space may be discrete or continuous. Our focus is on systems where changes are local in that a small number of components change state while the remainder of the system is unchanged. A proof methodology is developed that ensures global properties, such as invariants and convergence, by guaranteeing local properties within subsystems. This methodology is used to prove the correctness of concrete examples. We present a PVS library of theorems and proofs that can be used to reduce the work required to develop and verify programs in this class. A transformation of these libraries to Java is also outlined.     

Novel defects in Al–Pd–Fe complex metallic alloys: A micromechanical modelling approach

Transmission electron microscopy investigations have revealed that in the face centred complex metallic alloy of C₂–Al–Pd–Fe, the dislocations mediating plastic flow are decorated by localized regions of body centred structure in the compressive part of their strain field thus forming composite defects. We calculated the properties of these defects using a micromechanical model. The Eshelby method was employed to estimate the energies involved in the formation of such defects in the face-centred C₂ phase. We could reproduce the experimentally observed features of the defects in terms of their size and spatial configuration. The model describes a unique mechanism of a non-equilibrium defect, i.e., a dislocation, being stabilized by the formation and interaction with another non-equilibrium defect, i.e., a nanometre sized inclusion of different structure.     

Left ventricular morphology in chronic renal failure by echocardiography

M-mode, two-dimensional, and Doppler echocardiography were performed in 38 chronic renal failure (CRD) patients on conservative management, 35 patients on hemodialysis, and 36 matched controls. The controls were matched for age, sex, and comorbidities. The incidence of hypertension, left ventricular (LV) end diastolic volume, LV end systolic volume, and LV mass index were significantly higher in patients on hemodialysis compared to the controls. The LV parameters in the predialysis patients were not significantly different from the controls, except the LV end systolic internal dimensions were significantly higher in the CRF patients. Multiple regression analysis underscored the strong association between increase in LV mass index (LVMI) and hypertension. The diabetic patients with renal failure had large LV internal diameter and end diastolic volume compared to non-diabetics. Systolic function was well preserved even in hypertensive and diabetic patients with uremia. The incidence of diastolic dysfunction and asymmetrical septal hypertrophy were not significantly different in the three groups of patients.     

Microstructure, permeability and rheological behavior of lost foam refractory coatings

The effect of microstructure on rheology and permeability of three commercial lost foam refractory coatings available on the market called samples I, II, and III, respectively was investigated in this study. Thermal gravimetric/differential thermal analysis (TG/DTA) method was used for detailed analysis of the organic components and to determine the thermal stability of the coatings. Particle shape and size and particle size distribution (PSD) were obtained by optical microscopy and morphological studies were carried out by scanning electron microscopy (SEM). Also the scanning electron microscopy energy dispersive X-ray analysis (SEM/EDXA) technique was used for elemental analysis of refractory particles. To determine the crystalline structure of the samples, X-ray diffraction (XRD) analysis was carried out. Permeability measurements were conducted with a modified apparatus originally used for determining the permeability of casting sand. Finally the rheological behavior of the samples was investigated using a rotating coaxial rheometer to provide the flow curve for coating suspensions. The studies revealed that coating I has the highest permeability, which can be due to its large mean particle size and wide particle size distribution (PSD). Furthermore it was found that the investigated refractory coatings behave as non-Newtonian fluids with shear thinning behavior. All coatings exhibited yield stresses, indicate that they behave as Bingham-type pseudoplastic fluids.     

Nitric oxide mediates sexual behavior in female rats

Nitric oxide (NO), an active free radical formed during the conversion of arginine to citrulline by the enzyme NO synthase (NOS), mediates vasorelaxation, cytotoxicity, and neurotransmission. Neurons containing NOS (NOergic) are located in the hypothalamus. These NOergic neurons control the release of several hypothalamic peptides. Release of NO from these NOergic neurons stimulates pulsatile release of luteinizing hormone-releasing hormone (LHRH) in vivo and LHRH release in vitro. LHRH not only induces LH release, which induces ovulation, but also facilitates female sexual behavior. Sexual behavior can be induced reliably in estrogen-primed ovariectomized female rats by progesterone (P). This behavior consists of proceptive behavior to attract the male and the assumption of a clear characteristic posture, lordosis, when mounted by the male. To ascertain the role of NO in the control of sexual behavior in female rats, an inhibitor of NOS, NG-monomethyl-L-arginine was microinjected into the third cerebral ventricle (3V) of conscious, ovariectomized, estrogen-primed rats with indwelling cannulae. NG-Monomethyl-L-arginine (10-1000 micrograms) prevented P-facilitated lordosis when administered intracerebroventricularly into the 3V, 20 min prior to the 3V injection of P. NG-Monomethyl-D-arginine, which does not inhibit NOS, did not inhibit lordosis under the same experimental conditions. Microinjection into the 3V of sodium nitroprusside (SNP), which spontaneously releases NO, facilitated lordosis in estrogen-primed rats in the absence of P. The facilitation of lordosis induced by either P or SNP was prevented by intracerebroventricular injection of hemoglobin, which binds NO. Lordosis facilitated by P or SNP was blocked by injection of LHRH antiserum into the 3V. The results are interpreted to mean that the P-facilitated lordosis response is mediated by LHRH release. Furthermore, since NO release from SNP also facilitates lordosis in the absence of P and this response could be blocked by LHRH antiserum, we conclude that P brings about the release of NO, which stimulates LHRH release that facilitates lordosis. Thus, the results indicate that NO induces LHRH release and that LHRH then plays a crucial role in mediation of sexual behavior in the female rats.     

Variability among males in sexually selected attributes.

Greater male than female variability is found in behavioral and morphological traits in animals. A theory that greater male variability is associated with variability in parental investment is described and contrasted with sexual strategies theory, which posits no sex differences in variability. Predictions from the theories were tested through meta-analyses of variance ratios for data sets involving sexually selected characteristics analyses (physical aggression and 5 aspects of mate choice) and 2 unlikely to have resulted from sexual selection (anger and self-esteem). Variation was significantly greater among men than women in 5 of the 6 former data sets and was similar for men and women in the latter 2 data sets, broadly supporting the predictions. A further analysis extends the theory to intellectual abilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

CW and pulsed mode transfer impedance measurements in coaxialcables

Transfer impedance measurements have been performed both in frequency and time domains. CW measurements were performed using a matched triaxial system, a quintaxial system, and stripline injection. For nuclear electromagnetic pulse (NEMP) purposes, measurements up to a maximum frequency of 200 MHz are sufficient. For this frequency range the matched triaxial system was found to be the most convenient. Amplitude and phase measurements in different cables are discussed. Direct and indirect injection was employed in the time domain measurements. A delayed coupling is demonstrated when the diffusion term is dominant in the transfer impedance. In a magnetically shielded cable, hysteresis and saturation effects have been observed. At 5 kA the transfer impedance of the magnetically shielded cable increased by an order of magnitude due to saturation     

Aggregation in sensor networks: an energy–accuracy trade-off

Wireless ad hoc sensor networks (WASNs) are in need of the study of useful applications that will help the researchers view them as distributed physically coupled systems, a collective that estimates the physical environment, and not just energy-limited ad hoc networks. We develop this perspective using a large and interesting class of WASN applications called aggregation applications. In particular, we consider the challenging periodic aggregation problem where the WASN provides the user with periodic estimates of the environment, as opposed to simpler and previously studied snapshot aggregation problems. In periodic aggregation our approach allows the spatial–temporal correlation among values sensed at the various nodes to be exploited towards energy-efficient estimation of the aggregated value of interest. Our approach also creates a system level energy vs. accuracy knob whereby the more the estimation error that the user can tolerate, the less is the energy consumed. We present a distributed estimation algorithm that can be applied to explore the energy–accuracy subspace for a subclass of periodic aggregation problems, and present extensive simulation results that validate our approach. The resulting algorithm, apart from being more flexible in the energy–accuracy subspace and more robust, can also bring considerable energy savings for a typical accuracy requirement (fivefold decrease in energy consumption for 5% estimation error) compared to repeated snapshot aggregations.