Effects of aging, diet, and sex on plasma glucose, fructosamine, and lipid concentrations in barrier-raised Fischer 344 rats

We studied the relationships of plasma glucose, fructosamine, triglycerides, and cholesterol as a function of age, gender, and diet in barrier-raised Fischer 344 rats aged 5 to 26 months, fed a diet either ad libitum or restricted to 60% of the ad libitum caloric intake. The complex relationships of these plasma levels to age, gender, and diet led to the development of a model with age, diet, and sex as covariates. Overall, fasting plasma glucose concentrations were reduced by approximately 25% in rats on the restricted diet, compared to ad libitum-fed animals. There was a significant age-dependent decline in glucose levels in male animals, whereas in females there was an increase in plasma glucose with aging. Plasma fructosamine levels in calorie-restricted animals, overall, were reduced by 7% compared to levels in animals fed ad libitum. There was a significant positive correlation between plasma glucose and fructosamine levels. Mean plasma triglyceride content was decreased by 50% in calorie-restricted rats compared to ad libitum-fed animals. A significant decrease in triglyceride levels with increasing age was seen in male animals, and an increase with aging in females. There was a significant positive correlation between plasma glucose and triglyceride levels. Plasma cholesterol levels in calorie-restricted animals were reduced by 7% compared to levels in ad libitum-fed animals. An increase of cholesterol concentration with aging was significant in both males and females. Analysis of the data showed that there were significant differences between male and female Fischer 344 rats in the response of plasma glucose and fructosamine to aging and calorie restriction. Changes of plasma triglyceride and cholesterol with aging and dietary calorie restriction were also different in males and females. Studies of the effect of aging on glycemia and blood lipid content should take into account the contributions of animal sex.     

Children's Physiological Indices of Empathy and Their Socioemotional Adjustment: Does Caregivers' Expressivity Matter?

Relations of heart rate and skin conductance reactions to mildly evocative empathy-inducing slides with socioemotional functioning were examined for 154 children (mean age = 9 years, 5 months). In addition, maternal expressivity was tested as a moderator of these relations. Parents and teachers rated children's socioemotional functioning, and a behavioral measure of children's regulation was obtained. Boys who exhibited higher skin conductance and higher heart rate to slides depicting negative emotions were better regulated, less emotionally intense, and better adjusted than their peers. Furthermore, boys' regulation and adjustment were positively related to such physiological responding to negative slides if maternal negative expressivity was relatively low or moderate, but not high. Fewer findings were obtained for girls or for positive slides. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Experimental demonstration of multiwavelength optical network with microwave subcarriers

The authors use the unique multiwavelength filtering capability of the acousto-optic tunable filter to demonstrate multiple broadband services with only one fixed-wavelength transmitter and receiver per user in the first experimental demonstration of a multiwavelength subcarrier network.<>     

High-speed switching of monolithic arrays ofgrating-surface-emitting diode lasers

The electrooptic switching properties of injection-coupled coherent two-dimensional grating-surface-emitting (GSE) laser arrays with multiple gain sections and quantum-well active layers are discussed. Within such an array of injection-coupled GSE lasers, a single gain section can act as an intracavity saturable loss element that can modulate the output of the entire array. Experimental results demonstrate efficient subnanosecond switching of high-power GSE laser arrays by operating only one gain section as an intracavity loss modulator     

Optimal pretensioned forces for cable networks

A computer software package for the static and dynamic analyses of cable networks has been developed. The algorithm involves the Newton-Raphson method and Newmark's -method. The former iterative method takes care of the problem's nonlinearity, and the latter handles the time-marching scheme. In addition, an optimization subroutine based on the Neider and Mead Simplex method has been incorporated into the software to enable designers to determine the optimal design values of pretensioned forces leading to a stiffer cable network. The accuracy and convergence of the software were tested on some well-documented cable networks. Their optimal values of pretensioned forces for certain specified sets of loadings were also established.     

Interaction between a spherical inhomogeneity and two symmetrically placed penny-shaped cracks

Stress analysis is carried out for a three-dimensional elastic solid containing an elastic spherical inhomogeneity and two coplanar penny-shaped cracks. Each of the two cracks is located on either side of the elastic spherical inhomogeneity and the geometry is subjected to uniform tensile stress at infinity. The interaction between the inhomogeneity and the cracks is tackled by the superposition principle of elasticity theory and Eshelby's equivalent inclusion method. Analytical solutions for the stress intensity factors on the boundaries of the cracks and the stress field inside the inhomogeneity are evaluated in series form. Numerical calculations are reported for several special cases, and show the variations of the stress intensity factors and stress field inside the inhomogeneity with the configuration and elastic properties of the solid and the inhomogeneity.     

Vibration of symmetrically laminated cantilever trapezoidal composite plates

The paper presents a general numerical method for vibration analysis of symmetrically laminated cantilever thin trapezoidal composite plates. The Rayleigh-Ritz method, along with displacements assumed in the form of 2-D orthogonal polynomials, is used to solve the problems. These 2-D orthogonal polynomials are generated using a proposed recurrence formula. Several numerical examples are presented to demonstrate the accuracy, efficiency and versatility of the method. Natural frequencies and mode shapes for the trapezoidal plates are obtained for different numbers of layers, fibre orientations, and ratios. These results, to the author's knowledge, are first known in the open literature. Thus the present study may provide very useful information to the engineers who work in this area.     

人羟甲基戊二酸单酰辅酶A(HMG-CoA)还原酶催化域在大肠杆菌中的表达及纯化

参照1993年Frimpong等表达仓鼠同源酶催化域的研究结果，将PCR法制备的人HMG－CoA还原酶催化域cDNA克隆入表达载体pET30，使表达产物C端融合载体编码的His－Tag，以利产物的稳定和完整产物的纯化。     

Evaluation of Failure Capacity of Offshore Riser Protectors Under Vessel Impact

Conventional riser protectors, also known as riser-guards, are installed on fixed offshore platforms to protect risers from vessel impact. These space frame structures made of hollow mild steel tubular sections are mainly designed using the approach of boat fenders which may result in over- or under-protection provided to risers. Lack of in-depth study on the dynamic behavior and capacity of conventional riser-guards is considered to be the primary challenge for creative and efficient design of conventional riser protectors. This paper presents a detailed numerical investigation on the dynamic response, damage and failure mechanics of conventional steel riser-guards during accidental vessel collision using nonlinear finite element analysis. Collision forces equivalent to vessel collision with riser-guards for different spans were estimated to provide information for load-based design. Variation in damage patterns for broadside and bow impacts is presented for riser protectors with different spans. The actual capacity of a typical riser-guard in terms of maximum impact energy sustainable prior to failure was also determined from dynamic pushover analysis. The structural response and damage parameters presented in this study can be used for better understanding of damage mechanism and failure capacity of riser protectors which can act as a baseline for further design optimization, as well as the development of other alternative riser protection systems.     

Equilibria,kinetics and mechanism for the degradation of the cytotoxic compound L-NG-nitroarginine

L-N^G-nitroarginine (LNNA), an analog of L-arginine, is a competitive inhibitor of nitric oxide synthase which causes the selective reduction of blood flow to tumor cells. Despite the potential of LNNA to function as an adjuvant in cancer therapies, its poor solubility and stability have hindered the development of an injectable formulation of LNNA that is suitable for human administration. This work, for the first time, details a systematic study on the determination of equilibrium K_a constants and the rate law of LNNA degradation. The four K_a values of LNNA were determined to be 1.03, 1.10?×?10^?2, 2.51?×?10^?10, and 1.33?×?10^?13 M. From the kinetic and equilibrium studies, we have shown that the deprotonated form of LNNA is the main form of LNNA that undergoes degradation in aqueous media at room temperature. The rate law of LNNA degradation was found to be first order with respect to OH^? concentration and first order with respect to LNNA^? concentration. The rate constant at 25?°C and 1?atm was determined to be 0.04453 M^?1min^?1. A base catalyzed mechanism of LNNA degradation was proposed based on the kinetic study. The mechanism was found to be very useful in explaining the discrepancies and changes of the rate law at different pH values. It is thus recommended that LNNA should be formulated as a concentrated solution in acidic conditions for maximum chemical stability during storage and be diluted with a basic solution to near physiological pH just before administration.