Angiotensin-converting enzyme 2 is an essential regulator of heart function

Cardiovascular diseases are predicted to be the most common cause of death worldwide by 2020. Here we show that angiotensin-converting enzyme 2 (ace2) maps to a defined quantitative trait locus (QTL) on the X chromosome in three different rat models of hypertension. In all hypertensive rat strains, ACE2 messenger RNA and protein expression were markedly reduced, suggesting that ace2 is a candidate gene for this QTL. Targeted disruption of ACE2 in mice results in a severe cardiac contractility defect, increased angiotensin II levels, and upregulation of hypoxia-induced genes in the heart. Genetic ablation of ACE on an ACE2 mutant background completely rescues the cardiac phenotype. But disruption of ACER, a Drosophila ACE2 homologue, results in a severe defect of heart morphogenesis. These genetic data for ACE2 show that it is an essential regulator of heart function in vivo.     

沥青混合料水稳定性分析

根据沥青混合料的强度形成原理和破坏机理以及沥青混合料与水相互作用机理，着重从集料性质、沥青性质、混合料类型、集料粒径和面层压实层厚度等方面分析了影响沥青混合料水稳定性的因素，提出了应在集料选择、沥青选择、沥青混合料设计、加热与拌和、碾压工艺、环境等方面采取措施来改善沥青混合料的水稳定性。     

Inactivation of the apoptosis effector Apaf-1 in malignant melanoma

Metastatic melanoma is a deadly cancer that fails to respond to conventional chemotherapy and is poorly understood at the molecular level. p53 mutations often occur in aggressive and chemoresistant cancers but are rarely observed in melanoma. Here we show that metastatic melanomas often lose Apaf-1, a cell-death effector that acts with cytochrome c and caspase-9 to mediate p53-dependent apoptosis. Loss of Apaf-1 expression is accompanied by allelic loss in metastatic melanomas, but can be recovered in melanoma cell lines by treatment with the methylation inhibitor 5-aza-2'-deoxycytidine (5aza2dC). Apaf-1-negative melanomas are invariably chemoresistant and are unable to execute a typical apoptotic programme in response to p53 activation. Restoring physiological levels of Apaf-1 through gene transfer or 5aza2dC treatment markedly enhances chemosensitivity and rescues the apoptotic defects associated with Apaf-1 loss. We conclude that Apaf-1 is inactivated in metastatic melanomas, which leads to defects in the execution of apoptotic cell death. Apaf-1 loss may contribute to the low frequency of p53 mutations observed in this highly chemoresistant tumour type.     

Coherent spin manipulation without magnetic fields in strained semiconductors

A consequence of relativity is that in the presence of an electric field, the spin and momentum states of an electron can be coupled; this is known as spin-orbit coupling. Such an interaction opens a pathway to the manipulation of electron spins within non-magnetic semiconductors, in the absence of applied magnetic fields. This interaction has implications for spin-based quantum information processing and spintronics, forming the basis of various device proposals. For example, the concept of spin field-effect transistors is based on spin precession due to the spin-orbit coupling. Most studies, however, focus on non-spin-selective electrical measurements in quantum structures. Here we report the direct measurement of coherent electron spin precession in zero magnetic field as the electrons drift in response to an applied electric field. We use ultrafast optical techniques to spatiotemporally resolve spin dynamics in strained gallium arsenide and indium gallium arsenide epitaxial layers. Unexpectedly, we observe spin splitting in these simple structures arising from strain in the semiconductor films. The observed effect provides a flexible approach for enabling electrical control over electron spins using strain engineering. Moreover, we exploit this strain-induced field to electrically drive spin resonance with Rabi frequencies of up to approximately 30 MHz.     

华北山前平原典型井灌区地下水水位变化影响因素分析

为定量评估华北山前平原多因子对地下水水位动态变化的影响,选取华北山前平原典型井灌区石家庄市栾城区为研究区,从水量平衡角度分析了影响该地区地下水水位动态变化的主要影响因子;利用主成分回归分析法排除主要影响因子间的相互作用,定量分析了各综合因子对地下水水位回升的贡献率;构建了栾城地下水水位主成分-时间序列模型预测多因子影响下的华北山前平原地下水水位变化。结果表明:1994—2015年栾城地下水水位主要受本地气候因子、本地人类活动和上游人类活动三方面影响因子的共同作用,各因子对当地地下水水位回升的贡献率分别为11.7%、-50.9%和-37.4%,对这三方面影响因子起主导作用的影响因素分别为栾城降水量、栾城小麦和玉米的种植面积以及上游石家庄市区人口;1994—2015年栾城自然气候变化有利于该地区地下水资源的恢复,但人类活动对地下水资源的影响仍占主导作用。     

BEM Analysis of Wave Propagation in a Water-Filled Borehole in an Anisotropic Solid

This paper describes a time-domain boundary element method developed to analyze the interactions of acoustic and elastic waves near the interfaces between water and an anisotropic elastic solid. Two models are analyzed with one being the interface between two half spaces of fluid and solid and the other being a fluid region sandwiched by half space domains of anisotropic elastic solids. Both monopole and dipole point sources are used to generate an initial pressure wave in the fluid. Some snapshots of the transient wave behavior near the fluid-solid interfaces are given. The effect of the anisotropy in the solid on the pressure waveforms in the fluid is discussed. The numerical results allow detailed arrival identification and interpretation of acoustic and elastic waves propagating along the fluid-solid interfaces.     

A lysosomal enigma CLN5 and its significance in understanding neuronal ceroid lipofuscinosis

Cellular and Molecular Life Sciences - Neuronal Ceroid Lipofuscinosis (NCL), also known as Batten disease, is an incurable childhood brain disease. The thirteen forms of NCL are caused by mutations...     

Yield curve forecast combinations based on bond portfolio performance

We propose an economically motivated forecast combination strategy in which model weights are related to portfolio returns obtained by a given forecast model. An empirical application based on an optimal mean–variance bond portfolio problem is used to highlight the advantages of the proposed approach with respect to combination methods based on statistical measures of forecast accuracy. We compute average net excess returns, standard deviation, and the Sharpe ratio of bond portfolios obtained with nine alternative yield curve specifications, as well as with 12 different forecast combination strategies. Return‐based forecast combination schemes clearly outperformed approaches based on statistical measures of forecast accuracy in terms of economic criteria. Moreover, return‐based approaches that dynamically select only the model with highest weight each period and discard all other models delivered even better results, evidencing not only the advantages of trimming forecast combinations but also the ability of the proposed approach to detect best‐performing models. To analyze the robustness of our results, different levels of risk aversion and a different dataset are considered.     

A new simple temperature-controlled membrane oxygenator for the perfusion of isolated rat livers

A new temperature-controlled membrane oxygenator for perfusing isolated rat livers was assembled using a combination of heat-exchangeable rubber tubing and silicon rubber tubing. The apparatus supplied enough oxygen to satisfy the requirements of hemoglobin-free perfused livers.     

Acute toxicity of folic acid in mice

The toxicity of folic acid (PGA) was studied in different inbred strains of mice. LD50 values of PGA by the i.p. route showed a unique toxicity pattern. In some strains, convulsions, ataxia and weakness were observed. Histopathological study in strains S/RVCri, BDF1, DBA/2 and DBA/2fNCri showed acute renal tubular necrosis.