Rapid thinning of parts of the southern greenland ice sheet

Aircraft laser-altimeter surveys over southern Greenland in 1993 and 1998 show three areas of thickening by more than 10 centimeters per year in the southern part of the region and large areas of thinning, particularly in the east. Above 2000 meters elevation the ice sheet is in balance but thinning predominates at lower elevations, with rates exceeding 1 meter per year on east coast outlet glaciers. These high thinning rates occur at different latitudes and at elevations up to 1500 meters, which suggests that they are caused by increased rates of creep thinning rather than by excessive melting. Taken as a whole, the surveyed region is in negative balance.     

Neuroscience. Boosting working memory

Working out which areas of the brain become activated during the formation of working (short-term) memory has been greatly helped by functional magnetic resonance imaging (fMRI). In a Perspective, Robbins et al. discuss new findings (Furey et al.) with fMRI that reveal how working memory is enhanced by the drug physostigmine, which increases cholinergic function in the brain.     

Convection in the antarctic ice sheet leading to a surge of the ice sheet and possibly to a new ice age

The Antarctic surge theory of Pleistocene glaciation is reexamined in the context of thermal convection theory applied to the Antarctic ice sheet. The ice sheet surges when a water layer at the base of the ice sheet reaches the edge of the ice sheet over broad fronts and has a thickness sufficient to drown the projections from the bed that most strongly hinder basal ice flow. Frictional heat from convection flow promotes basal melting, and, as the ice sheet grows to the continental shelf of Antarctica, a surge of the ice sheet appears likely.     

PALEOCLIMATE: Glacial Climate Instability

Throughout the last glacial period, rapid climatic changes called Dansgaard-Oeschger (D-O) events occurred in the Northern Hemisphere. As Labeyrie discusses in his Perspective, these events are ideal targets for testing our understanding of climate change and developing climatic change models. Important steps toward understanding D-O events, particularly regarding the role of the low latitudes, are now reported by Hughen et al. and Peterson et al.     

Comment on "Major Australian-Antarctic plate reorganization at Hawaiian-Emperor bend time"

Whittaker et al. (Reports, 5 October 2007, p. 83) presented reconstructions for Australia and Antarctica showing a change in relative plate motion approximately 53 million years ago, coincident with an inferred major global plate reorganization. This comment addresses problematic areas in their assumptions and the geological consequences of their reconstructions.     

LIQUID CRYSTALS: New Banana Phases

Liquid crystals-materials that flow like a fluid but are optically anisotropic like a crystal-exhibit large responses to modest external disturbances. In his Perspective, Lubensky discusses the advances reported in two papers in this issue, both of which involve liquid crystals made from V-shaped or bent-core molecules. Walba et al. report a synthetic strategy for producing a ferroelectric phase from achiral bent-core molecules. Pratibha et al. show that new liquid crystalline phases form when bent-core molecules are mixed with a particular class of rodlike molecules. These papers introduce new molecular designs that yield new liquid crystalline phases with controlled structure and properties.     

中国象甲科分类研究综述

象甲总科中国分类系统主要包括蔡邦华(1973)6科系统、赵养昌等(1980)5科系统、李鸿兴等(1986)14科系统及杨星科(1999)12科系统，目前，国内广泛采用的是赵养昌等的5科系统；象甲科中国分类系统主要包括蔡邦华(1973)16亚科系统、赵养昌等(1980)26亚科系统及李鸿兴等(1986)33亚科系统，国内广泛采用的是赵养昌等的26亚科系统．中国对象甲科的分类研究经历了西方学者研究阶段(1758—1927)、应用基础研究阶段(1928—1973)、系统分类奠基阶段(1974—1980)及系统分类发展阶段(1981年至今)4个时期．     

不同立地闽粤栲群落药用植物种群数量特征

以封育28 a较好立地、一般立地及封育8 a较差立地闽粤栲群落为对象,分析主要药用植物种群数量特征。在较好立地上,乔木层主要药用植物为山杜英、老鼠刺、幌伞枫等;在灌木层,主要药用植物为山杜英、毛冬青、老鼠刺等;在草本层,主要药用植物为狗脊、杜茎山、菜蕨等。在一般立地上,乔木层主要药用植物为山杜英、南酸枣和山乌桕等;在灌木层,主要药用植物为山杜英、老鼠刺和朱砂根等;在草本层,主要药用植物为狗脊、芒萁及朱砂根等。在较差立地上,乔木层主要药用植物为杉木、杜鹃和山杜英等;在灌木层,主要药用植物为芒萁、白花苦灯笼及朱砂根等;在草本层,主要药用植物为扇叶铁线蕨、毛冬青及芒萁等。     

异种动物细胞核移植研究现状及相关问题的探讨

随着体细胞核移植相继在多种动物中取得成功 ,异种细胞核移植技术在拯救濒危野生动物、人类干细胞克隆和细胞核质互作研究等方面具有特殊意义 ,受到广泛重视并取得了很大进展。文章对异种细胞核移植技术研究现状进行了综述 ,并对其应用前景和存在的问题进行了探讨。     

SEISMOLOGY: Watching the Hayward Fault

The Hayward fault, located on the east side of the San Francisco Bay, represents a natural laboratory for seismologists, because it does not sleep silently between major earthquakes. In his Perspective, Simpson discusses the study by Bürgmann et al., who have used powerful new techniques to study the fault. The results indicate that major earthquakes cannot originate in the northern part of the fault. However, surface-rupturing earthquakes have occurred in the area, suggesting that they originated to the north or south of the segment studied by Bürgmann et al. Fundamental questions remain regarding the mechanism by which plate tectonic stresses are transferred to the Hayward fault.     

Corrections and clarifications

In the Research News article "Pot, heroin unlock new areas for neuroscience" by Marcia Barinaga (18 Dec., p. 1882), the diagram of the molecule anandamide on page 1883 was incorrect. The correct structure appears on page 1948 of the same issue, in figure 1A of the report "Isolation and structure of a brain constituent that binds to the cannabinoid receptor" by W. A. Devane et al. (p. 1946).     

福建引种丛生竹座标法综合评定及选择

丛生竹是经济产量较高的一类竹种，因此对福建省丛生竹引种情况进行了全面调查，确定6个主要生长性状作为评价指标。分别就龙岩、华安、南平的丛生竹种采用座标法综合评价与排序，考评结果表明：0-2级寒害级别丛生竹可作为邻近地区大面积推广的首选竹种；霞山坭竹、粉单竹、花眉竹、慈竹、大眼竹、银丝大眼竹等为材用竹种；银丝竹、妈竹、长枝竹等在较差立地上种植以作水土保持竹种；花吊丝竹、吊丝单竹、麻竹、勃氏甜龙竹、绿竹等为较好的笋用竹种，它们均具有较大的推广和开发价值。     

辽宁省主要造林树种抗火性能测定及其抗火树种的筛选

本文在辽宁省境内选取主要造林树种或有抗火希望树种共２０种，对每个树种从含水率、油脂率、灰分率、耐燃点、树皮厚度等抗火性能指标进行了测定，综合分析了测定结果，筛选出了核桃楸、水曲柳、色赤杨等７个树种难燃抗火，并结合各树种的生物学和物候特点，择优选择了辽宁省各地区的主要抗火树种。     

Heat flux anomalies in Antarctica revealed by satellite magnetic data

The geothermal heat flux is an important factor in the dynamics of ice sheets; it affects the occurrence of subglacial lakes, the onset of ice streams, and mass losses from the ice sheet base. Because direct heat flux measurements in ice-covered regions are difficult to obtain, we developed a method that uses satellite magnetic data to estimate the heat flux underneath the Antarctic ice sheet. We found that the heat flux underneath the ice sheet varies from 40 to 185 megawatts per square meter and that areas of high heat flux coincide with known current volcanism and some areas known to have ice streams.     

我国滇黔桂三省区竹亚科的两个新记录属

通过标本和引种于’９９昆明世博会竹园的活体植物材料的观察,报道了新小竹属（Ｎｅｏｍｉｃｒｏｃａｌａｍｕｓ Ｋｅｎｇ ｆ．）的新小竹「Ｎ．ｐｒａｉｎｉｉ（Ｇａｍｂｌｅ）Ｋｅｎｇ ｆ．」在贵州和广西的新分布,单枝竹属（Ｍｏｎｃｌａｄｕｓ Ｌ．Ｃ．Ｃｈｉａ ｅｔ ａｌ）的箭竿竹（Ｍｏｎｏｃｌａｄｕｓ ｓａｘａｔｉｌｉｓ Ｃｈｉａ ｅｔ ａｌ ｖａｒ．ｓｏｌｉｄｕｓ（Ｃ．Ｄ．Ｃｈｕ ｅｔ Ｃ．ｓ．Ｃｈａｏ）Ｃｈｉａ）和芸香竹（Ｍ．ａｍｐｌｅｘｉｃａｕｌｉｓ Ｃｈｉａ ｅｔ ａｌ）分别在贵州和云南的新分布。     

两种蝽茧蜂外生殖器比较(膜翅目:茧蜂科:优茧蜂亚科)

介绍了湖南蝽茧蜂及其近缘种橙足蝽茧蜂雌雄外生殖器的构造和区别,并附有两种茧蜂雌雄外生殖器图。     

Comment on papers by Chong et al., Nishio et al., and Suri et al. on diabetes reversal in NOD mice

Chong et al., Nishio et al., and Suri et al. (Reports, 24 March 2006, pp. 1774, 1775, and 1778) confirmed that treating nonobese diabetic (NOD) mice with an immune adjuvant and semisyngenic spleen cells can reverse the disease but found that spleen cells did not contribute to the observed recovery of pancreatic islets. We show that islet regeneration predominately originates from endogenous cells but that introduced spleen cells can also contribute to islet recovery.     

Erratum

In the report "Positron emission tomography reveals elevated D(2) dopamine receptors in drugnaive schizophrenics" by D. F. Wong et al. (19 Dec., p. 1558), reference 8 should have read, "D. F. Wong et al., Science 226, 1393 (1984); D. F. Wong et al., J. Cereb. Blood Flow Metab. 6, 147 ( 1986).     

衡阳市野生草本植物的园林景观应用

2013年3～12月,先后对湖南省衡阳市的典型山脉、公园、植物园、风景区等地的野生草本植物以及他们的应用进行实地调查。根据草本植物选择标准,筛选出11科29种具有观赏价值的野生草本植物,详细地描述其性状、景观价值和在园林中的应用,提出了衡阳地区野生草本植物合理开发与保护和意见,为更好地发掘野生草本植物在园林中的应用提供依据。     

Structural biology. The ribosome is a ribozyme

Ribosomes, the cellular factories that manufacture proteins, contain both RNA and protein, but exactly how all of the different ribosomal components contribute to protein synthesis is still not clear. Now, as Thomas Cech explains in his Perspective, atomic resolution of the structure of the large ribosomal subunit reveals that, as predicted by those convinced of a prebiotic RNA world, RNA is the catalytic component with proteins being the structural units that support and stabilize it (Ban et al., Nissen et al., Muth et al.).