上海市百岁老人的谱系及其分析

本文调查了上海市百岁老人的性别、职业和谱系,并绘制了57个完整的寿命谱系图,其中男性10名(占总数的17.5%),女性47名(占82.5%).男性中脑力劳动者4名(占男性总数的40%),体力劳动者6名(占60%);女性中脑力劳动者1人(占女性总数的2.1%),体力劳动者3人(占6.4%),操持家务者43人(占91.5%).有长寿家族史者40人(占寿命家族史清楚者的70.2%),无长寿家族史者17人(占29.8%).百岁老人配偶寿长≥70岁者,其已故子女的平均寿命高于配偶<70岁的.作者认为长寿是遗传的,并着重从遗传和环境两方面分析了女寿星数明显多于男寿星数的原因.     

协方差矩阵的MINQUE和简单估计的比较

在二次损失函数下,作者研究了多元线性模型协方差矩阵的MINQUE估计和简单估计的比较问题,其中多元线性模型的设计矩阵和离散矩阵可以不满秩,得到了一个充分和必要条件。     

心肌宁冲剂对抗垂体后叶素所致大鼠急性心肌缺血实验研究

心肌宁冲剂按1.75g/kg,0.875g/kg剂量,每天早晚分两次灌胃给药,连续7天,均能明显对抗垂体后叶素所诱发的大鼠急性心肌缺血的心电图改变。     

宇航员头部冲击的模拟创伤实验研究

该文通过３４只罗猴头颈实验研究，从中决定罗猴的颅脑损伤容限．当颅脑受到冲击时，颅壳发生局部变形瞬间，大脑亦发生变形，致使颅内压升高．利用这些结果来确定它的损伤机制，以模拟宇航员在冲击载荷下的创伤分析模型，将有助于进行临床创伤治疗和宇航弹射时的防护．     

An abrupt climate event in a coupled ocean-atmosphere simulation without external forcing

Temperature reconstructions from the North Atlantic region indicate frequent abrupt and severe climate fluctuations during the last glacial and Holocene periods. The driving forces for these events are unclear and coupled atmosphere-ocean models of global circulation have only simulated such events by inserting large amounts of fresh water into the northern North Atlantic Ocean. Here we report a drastic cooling event in a 15,000-yr simulation of global circulation with present-day climate conditions without the use of such external forcing. In our simulation, the annual average surface temperature near southern Greenland spontaneously fell 6-10 standard deviations below its mean value for a period of 30-40 yr. The event was triggered by a persistent northwesterly wind that transported large amounts of buoyant cold and fresh water into the northern North Atlantic Ocean. Oceanic convection shut down in response to this flow, concentrating the entire cooling of the northern North Atlantic by the colder atmosphere in the uppermost ocean layer. Given the similarity between our simulation and observed records of rapid cooling events, our results indicate that internal atmospheric variability alone could have generated the extreme climate disruptions in this region.     

Live birth after ovarian tissue transplant

Radiation and high-dose chemotherapy may render women with cancer prematurely sterile, a side-effect that would be avoided if ovarian tissue that had been removed before treatment could be made to function afterwards. Live offspring have been produced from transplanted ovarian tissue in mice and sheep but not in monkeys or humans, although sex steroid hormones are still secreted. Here we describe the successful transplantation of fresh ovarian tissue to a different site in a monkey, which has led to the birth of a healthy female after oocyte production, fertilization and transfer to a surrogate mother. The ectopically grafted tissue functions without surgical connection to major blood vessels and sets the stage for the transplantation of cryopreserved ovarian tissue in humans.     

Strong contributors to network persistence are the most vulnerable to extinction

The architecture of mutualistic networks facilitates coexistence of individual participants by minimizing competition relative to facilitation. However, it is not known whether this benefit is received by each participant node in proportion to its overall contribution to network persistence. This issue is critical to understanding the trade-offs faced by individual nodes in a network. We address this question by applying a suite of structural and dynamic methods to an ensemble of flowering plant/insect pollinator networks. Here we report two main results. First, nodes contribute heterogeneously to the overall nested architecture of the network. From simulations, we confirm that the removal of a strong contributor tends to decrease overall network persistence more than the removal of a weak contributor. Second, strong contributors to collective persistence do not gain individual survival benefits but are in fact the nodes most vulnerable to extinction. We explore the generality of these results to other cooperative networks by analysing a 15-year time series of the interactions between designer and contractor firms in the New York City garment industry. As with the ecological networks, a firm's survival probability decreases as its individual nestedness contribution increases. Our results, therefore, introduce a new paradox into the study of the persistence of cooperative networks, and potentially address questions about the impact of invasive species in ecological systems and new competitors in economic systems.     

Structural basis for the function and inhibition of an influenza virus proton channel

The M2 protein from influenza A virus is a pH-activated proton channel that mediates acidification of the interior of viral particles entrapped in endosomes. M2 is the target of the anti-influenza drugs amantadine and rimantadine; recently, resistance to these drugs in humans, birds and pigs has reached more than 90% (ref. 1). Here we describe the crystal structure of the transmembrane-spanning region of the homotetrameric protein in the presence and absence of the channel-blocking drug amantadine. pH-dependent structural changes occur near a set of conserved His and Trp residues that are involved in proton gating. The drug-binding site is lined by residues that are mutated in amantadine-resistant viruses. Binding of amantadine physically occludes the pore, and might also perturb the pK(a) of the critical His residue. The structure provides a starting point for solving the problem of resistance to M2-channel blockers.