Global AIDS epidemic: time to turn the tide

HIV/AIDS is catastrophic both from a public health perspective and in terms of its impact on economic and social stability in many of the most severely affected nations, including virtually all of southern Africa. A public health response alone is insufficient to address this devastating epidemic. Political leadership at the highest levels is needed to mobilize a multisectoral response to the impact of HIV/AIDS on educational systems, industry, agriculture, the military, and other sectors. With a few notable exceptions, political response was slow to mobilize in the early years of the epidemic, but response has dramatically improved in the past 18 months. The Joint United Nations Programme on HIV/AIDS (UNAIDS) is involved in ongoing efforts to encourage political leaders to make a multisectoral response to the epidemic a major focus of their national plans.     

Legal rights and duties in the AIDS epidemic

This article provides an overview of some major areas of legal concern in which the AIDS epidemic is having an impact. The rights of infected individuals to testing, treatment, and confidentiality are reviewed, and emphasis is given to their claims to nondiscrimination regarding access to health care, employment, housing, education, insurance, and related interests. Infected persons' duties to contain transmission of AIDS are outlined under principles of criminal and civil law, including liability for provision of contaminated blood products. Uninfected people's general rights to protection are considered, and health professionals' and authorities' rights and duties are given more detailed attention. In conclusion, some legal developments outside the United States are reviewed.     

The molecular fossil record of oleanane and its relation to angiosperms

Oleanane has been reported in Upper Cretaceous and Tertiary source rocks and their related oils and has been suggested as a marker for flowering plants. Correspondence of oleanane concentrations relative to the ubiquitous microbial marker 17alpha-hopane with angiosperm diversification (Neocomian to Miocene) suggests that oleanane concentrations in migrated petroleum can be used to identify the maximum age of unknown or unavailable source rock. Rare occurrences of pre-Cretaceous oleanane suggest either that a separate lineage leads to the angiosperms well before the Early Cretaceous or that other plant groups have the rarely expressed ability to synthesize oleanane precursors.     

HIV/AIDS in women: an expanding epidemic

More than 20 years into the human immunodeficiency virus-type 1 (HIV-1) epidemic, women account for nearly half of the 40 million people living with HIV-1 worldwide, with an even higher proportion existing in developing countries. Social determinants of female vulnerability to HIV-1 include gender disparities, poverty, cultural and sexual norms, lack of education, and violence. Women are also more susceptible to HIV-1 because of hormonal changes, vaginal microbial ecology and physiology, and a higher prevalence of sexually transmitted diseases. Prevention strategies must address the wide range of gender inequalities that promote the dissemination of HIV-1.     

Reconstruction and future trends of the AIDS epidemic in the United States

There has been considerable uncertainty in estimates of past and current human immunodeficiency virus (HIV) infection rates in the United States. Statistical estimates of historical infection rates can be obtained from acquired immunodeficiency syndrome (AIDS) incidence data and the incubation period. However, this approach is subject to a number of sources of uncertainty and two other approaches, epidemic models of HIV transmission and surveys of HIV prevalence, are used to corroborate and refine the statistical estimates. Analyses suggest the HIV infection rate in the United States grew rapidly in the early 1980s, peaked in the mid-1980s, and subsequently declined markedly. Due both to the decline in the underlying infection rate and to the development of effective therapies that may delay AIDS diagnosis, overall AIDS incidence may plateau during the next 5 years. However, the number of individuals with advanced HIV disease without a diagnosis of AIDS who could potentially benefit from therapy is expected to increase 40% by 1995 as infected individuals progress to more advanced stages of HIV disease. Thus, although the overall HIV infection rate has declined, the demands on the U.S. health care system for treatment and care of HIV-infected individuals remain enormous.     

Metacontrast: its relation to evoked potentials

Electrophysiological correlates of metacontrast were studied by means of averaged evoked potentials recorded from the scalp in man. Under conditions in which the brightness of the first of two successive stimuli appears diminished there is no accompanying attenuation of the evoked potentials to that stimulus. The results suggest that the amplitude and latency of evoked potentials correlate with stimulus intensity but not with brightness.     

百合病流行的主要因素及综合防治技术

通过近4年对百合病害发生流行原因的调查研究得出重度、湿害、种球带菌、肥害、密度大等是其流行的主要因素,并发现百合病害在田间表现为由多种病原菌共同引起的综合症状。探索出以生产无公害百合为目标,采取包括农业防治,土壤、种球处理,大田药物喷施等综合防治措施,控制其流行。     

在豆光合日变化及其与生态因子的关系

在自然条件下，大豆鄂豆8号的光合日变化曲线为双峰型，但中午光合速率下降较少，且下午也具有较高的光合速率；光合速率与生态因子存在一定的相关性，其中光合速率与光照强度的相关系数最大，与相对湿度和叶片温度的相关系数较小。     

大豆光合日变化及其与生态因子的关系

在自然条件下 ,大豆鄂豆 8号的光合日变化曲线为双峰型 ,但中午光合速率下降较少 ,且下午也具有较高的光合速率 ;光合速率与生态因子存在一定的相关性 ,其中光合速率与光照强度的相关系数最大 ,与相对湿度和叶片温度的相关系数较小。     

稻田土壤还原性物质特征及与甲烷排放的关联性分析

以南方稻田土壤的定位试验为研究对象,选取其中的五种不同施肥(无肥、化肥、猪粪+化肥、鸡粪+化肥、稻草+化肥)处理,监测了水稻生长期间土壤活性还原性物质、活性有机还原性物质、亚铁(Fe2+)含量、土壤Eh值和甲烷(CH4)排放的动态变化,分析还原性物质与CH4排放的关系。结果表明,水稻生长前期稻田CH4排放通量、土壤活性还原性物质、活性有机还原性物质和Fe2+含量均较高,并随水稻生长呈逐渐下降的趋势;而土壤Eh在水稻整个生育期介于-238至118 mv之间,且为水稻生长前期低,后期高。施用有机肥后的土壤活性还原性物质和Fe2+含量比化肥处理平均分别增加了13%和11%,而土壤Eh值则低于无肥和化肥处理。相关分析表明,CH4排放通量与土壤中活性还原性物质、Fe2+均呈极显著正相关关系,而与土壤Eh呈极显著负相关关系。通过逐步回归分析进一步表明,土壤中Fe2+含量显著影响稻田CH4排放,控制稻田土壤中Fe2+含量有利于稻田CH4的减排。     

The dynamics of the stratospheric polar vortex and its relation to springtime ozone depletions

Dramatic springtime depletions of ozone in polar regions require that polar stratospheric air has a high degree of dynamical isolation and extremely cold temperatures necessary for the formation of polar stratospheric clouds. Both of these conditions are produced within the stratospheric winter polar vortex. Recent aircraft missions have provided new information about the structure of polar vortices during winter and their relation to polar ozone depletions. The aircraft data show that gradients of potential vorticity and the concentration of conservative trace species are large at the transition from mid-latitude to polar air. The presence of such sharp gradients at the boundary of polar air implies that the inward mixing of heat and constituents is strongly inhibited and that the perturbed polar stratospheric chemistry associated with the ozone hole is isolated from the rest of the stratosphere until the vortex breaks up in late spring. The overall size of the polar vortex thus limits the maximum areal coverage of the annual polar ozone depletions. Because it appears that this limit has not been reached for the Antarctic depletions, the possibility of future increases in the size of the Antarctic ozone hole is left open. In the Northern Hemisphere, the smaller vortex and the more restricted region of cold temperatures suggest that this region has a smaller theoretical maximum for column ozone depletion, about 40 percent of the currently observed change in the Antarctic ozone column in spring.     

Anaphylatoxin in its relation to the complement system

The fifth component of complement that reacts hemolytically in the guinea pig or rat complement system, C'3b, is intimately associated with the generation of anaphylatoxin. Anaphylatoxin was formed (i) if this purified component reacted with a washed, intermediate complex consisting of antigen, antibody, and the first four components of complement; (ii) if the component was treated with trypsin; or (iii) if the component was incubated with a material isolated from cobra venom together with a fraction from serum other than complement. The significance of this fifth component as anaphylatoxinogen is discussed, and a common mechanism is proposed for the generation of anaphylatoxin in whole serum.     

英语语言的复杂性及其与文化的关系

语言的复杂多样化是普通语言释义的实际表现形式，并且被认为是与语言使用者和语言使用的环境相关。语言与文化是一同发展和进化的，文化导致了对语言的不同解释和反应，其影响是深远的，在它们的整个历史中，二者一直相互依赖。