Mechanisms of reproductive suppression in female pine voles (Microtus pinetorum)

In co-operatively breeding birds and mammals, philopatric females are often reproductively suppressed. Many studies have focused on the functional significance of reproductive suppression, but further investigation of the mechanisms involved is required for a complete understanding of this process. This study investigated whether reproductive suppression in non-reproductive female pine voles (Microtus pinetorum) occurs as a result of lack of gamete maturation or lack of increase in LH. The behaviour of male pine voles was also examined to determine whether they show a preference for the mother versus her daughter, as lack of male stimulation may inhibit an increase of LH in daughter pine voles. Ovarian development and circulating LH concentrations were investigated in females housed with a prospective mate in the presence or absence of a parent. Maturation of gametes was not affected by the presence of a parent. In the presence of the mother, there was no increase in LH, as was observed in females housed with or exposed to a novel male. Males spent more time with mothers and possibly showed a preference for mating with the mother. These results are consistent with the contention that ovulation does not occur in female pine voles housed in the presence of their mother; however, it is not clear whether the lack of ovulation is caused by lack of stimulation from the male or suppression by the mother.     

Global and Local Nonlinear System Responses under Narrowband Random Excitations. II: Prediction, Simulation, and Comparison

The response behavior of the single-degree-of-freedom (SDOF) nonlinear structural system subjected to narrowband stochastic excitations studied in Part I is investigated via simulations to verify the stochastic system characteristics assumed in the development of the semianalytical method. In addition, to demonstrate the accuracy of the method, predicted response–amplitude probability distributions are presented and compared to simulation results. Numerical simulations are conducted by directly integrating the SDOF system with the narrowband excitation modeled by the 1971 Shinozuka formulation. It is observed that the proposed semianalytical method is capable of accurately characterizing the stochastic response behavior of the nonlinear system by predicting the response–amplitude probability distribution and capturing the trends of variations in the response–amplitude statistical properties. In both the primary and the subharmonic resonance regions, good agreements between the response–amplitude probability distributions predicted by the semianalytical method and obtained from simulation results are observed both qualitatively and quantitatively. In addition, trends of the variations in the probability masses associated with the modes with variations in excitation parameters (bandwidth and variance) are captured.     

1966-2006年美国儿童游戏场的变化

20世纪60年代美国的游戏场发展到了一个高峰。建筑师和雕塑家,包括路易·康和野口勇在其中扮演了重要的角色,他们合作设计的纽约河畔公园的阿黛儿·柔森沃德·利维游戏场彻底改变了美国传统游戏场的概念,而将艺术和游戏结合起来,体现"游玩必须是自由和不受限制的,空间是通过那些不是模仿自然但无限变化的形状而被发现的"。而从20世纪70年代开始,对安全和责任的过分关注取代了美国的游戏场的创新。在经历了几十年建造游戏场只是满足公认的标准而没有任何创新的衰退期后,一些重要的设计师们开始重新为孩子们设计富有创意和挑战性的游戏环境。     

O2 and N2O activation by Bi-, Tri-, and tetranuclear Cu clusters in biology

Copper-cluster sites in biology exhibit unique spectroscopic features reflecting exchange coupling between oxidized Cu's and e (-) delocalization in mixed valent sites. These novel electronic structures play critical roles in O 2 binding and activation for electrophilic aromatic attack and H-atom abstraction, the 4e (-)/4H (+) reduction of O 2 to H 2O, and in the 2e (-)/2H (+) reduction of N 2O. These electronic structure/reactivity correlations are summarized below.     

Modeling changes in rheological properties of potatoes during storage under constant and variable conditions

The changes in rheological properties of potatoes stored at 5, 15, 25 °C and variable (fluctuating) temperature for 16 or 26 weeks were evaluated in terms of elasticity and viscosity parameters using axial compression and creep tests. Cylindrical test specimens (15 mm diameter and 30 mm long) were used. A third-degree polynomial best fitted the force-deformation curves in axial compression test (R²=0.98-0.99) whereas a four-element (Burgers) mechanical model adequately described the creep response of potatoes (R²=0.95-0.99). The tangent modulus of elasticity in axial compression and elasticity and viscosity parameters in creep tests in general decreased significantly (P<0.05) with increase in storage time both under constant and variable storage conditions. The changes in rheological properties of potatoes stored under constant storage condition were sufficiently described by a modified exponential model (R²=0.89-0.96) except for the viscosity parameter of the Maxwell component of the four-element model. The logarithm of degradation rate constant, k, and the constant, n, were linearly related to storage temperature. For the variable storage condition, a bulk mean temperature (T_bm) was calculated to account for a series combination of storage time and temperature to which the potatoes were subjected. The changes in rheological properties due to variable storage temperature were then described as a function of T_bm and storage time, t_s, using stepwise multiple regression. The result indicated that except the viscosity parameter of the Maxwell component of the four-element model, it was possible to describe the changes in rheological properties as a function of T_bm and t_s (R²=0.84-0.99).     

SmAlO<Subscript>3</Subscript> + Ba(Zn<Subscript>1/2</Subscript>Nb<Subscript>2/3</Subscript>)O<Subscript>3</Subscript>: microwave ceramic composite

The 0.1SmAlO₃ + 0.9Ba(Zn_1/2Nb_2/3)O₃ composite is prepared through the solid state ceramic route. The structure of the materials is studied using X-Ray diffraction analysis. The microstructure is studied using scanning electron microscopy and the elemental composition by energy dispersive spectrometry. The dielectric properties in the radio and microwave frequencies are measured. The photoluminescence property of the sample is also analyzed. The material has dielectric constant (ε _r ) = 37, temperature coefficient of resonant frequency (τ _f ) = +25 ppm/°C and high quality factor. The measured values of ε _r and τ _f are compared with the corresponding theoretical values. The composite is useful in the field of optoelectronics and microwave communication.     

Modular integration of a matrix converter

The future development of high‐performance power electronics will rely increasingly on system‐level integration, where semiconductor devices are co‐packaged with other active and passive components (e.g., gate drivers, filter capacitors, and inductors) into a power module. In view of the widespread electrification of pivotal elements of the energy generation and distribution infrastructure (e.g., smart grids, electric aircraft, electric vehicles), modularity is also increasingly gaining importance as a means of enhancing overall system performance and reducing long‐term maintenance costs. This paper focuses on the development of a highly integrated three‐to‐one phase matrix converter for avionic applications. It proposes an integration approach that enhances the volumetric and gravimetric power handling capability, with enhanced electromagnetic and electrothermal performance as compared to established solutions. Maintenance is also simplified by the modular assembly approach. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

What determines farmers’ adaptive capacity? Empirical evidence from Malawi

This paper assesses farmers’ incentives and conditioning factors that hinder or promote adaptation strategies and evaluates their impact on crop productivity by using data from nationally representative sample households in Malawi. We employed multivariate probit (MVP) and multinomial treatment effect (MTE) techniques to model adoption decisions and their yield impact. Exposure to delayed onset of rainfall and greater climate variability was positively associated with the choice of risk-reducing agricultural practices such as tree planting, legume intercropping, and soil and water conservation (SWC) but reduced the use of inputs (such as inorganic fertilizer) whose risk reduction benefits are uncertain. Concerning household adaptive capacity, wealthier households were more likely to adopt both modern and sustainable land management (SLM) inputs and were more likely to adopt SLM inputs on plots that were under greater security of tenure. In terms of system-level adaptive capacity, rural institutions, social capital and supply-side constraints were key in governing selection decisions for all practices considered, but particularly for tree planting and both organic and inorganic fertilizer applications. A combination of practices gave rise to higher yields suggesting that this might be a course of action that would sustain growth of yield in Malawi in the future.     

State legislators' perceptions of lobbyists and lobbying on tobacco control issues

OBJECTIVE: To determine state legislators' perceptions about health and tobacco lobbyists, their frequency of contact with these lobbyists, and the amount of campaign contributions from health professional organisations and the tobacco industry. DESIGN: Cross-sectional study. SUBJECTS: State legislators from North Carolina, Texas, and Vermont (USA), serving in 1994. MAIN OUTCOME MEASURES: Perceptions about lobbyists representing the tobacco industry, non-profit health organisations, and state medical societies with respect to their credibility, importance as sources of information, and persuasiveness; extent of lobbying activities; campaign contributions from health professional organisations and the tobacco industry. RESULTS: Almost all legislators reported that medical society and non-profit health organisation lobbyists are credible on tobacco issues and just over half believed that these lobbyists are important sources of information. More legislators said they could be persuaded by medical and health lobbyists than by tobacco lobbyists. Although health professional Political Action Committees (PACs) gave campaign contributions to more state legislators, and gave higher amounts on average, than tobacco PACs, legislators reported less contact with medical society lobbyists than tobacco lobbyists about tobacco issues. CONCLUSIONS: State legislators have positive attitudes toward lobbyists for non-profit health organisations and state medical societies regarding tobacco issues. These groups may be an underused resource for educating legislators about tobacco control measures.