Antarctic krill under sea ice: elevated abundance in a narrow band just south of ice edge

We surveyed Antarctic krill (Euphausia superba) under sea ice using the autonomous underwater vehicle Autosub-2. Krill were concentrated within a band under ice between 1 and 13 kilometers south of the ice edge. Within this band, krill densities were fivefold greater than that of open water. The under-ice environment has long been considered an important habitat for krill, but sampling difficulties have previously prevented direct observations under ice over the scale necessary for robust krill density estimation. Autosub-2 enabled us to make continuous high-resolution measurements of krill density under ice reaching 27 kilometers beyond the ice edge.     

Upwelling: oceanic structure at the edge of the arctic ice pack in winter

Observations taken on an expedition into the Arctic Ocean north of Spitsbergen indicated the existence of a region of wind-driven upwelling along the edge of the ice pack. Models underestimate the 12-kilometer width of the upwelling region.     

Eolian biogenic detritus in deep sea sediments: a possible index of equatorial ice age aridity

Opal phytoliths and freshwater diatoms, transported mainly in dust to the equatorial Atlantic, are common in sediments deposited when ocean waters were cool, and sparse in those deposited when waters were warm, during the last 1.8 million years. Climate in source areas of the southern Sahara apparently was more arid during glacials and more humid during interglacials.     

Cosmological magnetic field: a fossil of density perturbations in the early universe

The origin of the substantial magnetic fields that are found in galaxies and on even larger scales, such as in clusters of galaxies, is yet unclear. If the second-order couplings between photons and electrons are considered, then cosmological density fluctuations, which explain the large-scale structure of the universe, can also produce magnetic fields on cosmological scales before the epoch of recombination. By evaluating the power spectrum of these cosmological magnetic fields on a range of scales, we show here that magnetic fields of 10(-18.1) gauss are generated at a 1-megaparsec scale and can be even stronger at smaller scales (10(-14.1) gauss at 10 kiloparsecs). These fields are large enough to seed magnetic fields in galaxies and may therefore have affected primordial star formation in the early universe.     

Atrial natriuretic factor: a hormone produced by the heart

Systematic studies on the significance of the secretory-like morphological characteristic of cardiac atrial muscle cells of mammals led to the finding that these cells produce a polypeptide hormone. This hormone, described in 1981 as atrial natriuretic factor (ANF), is diuretic (natriuretic), hypotensive, and has an inhibitory effect on renin and aldosterone secretion. Thus, ANF probably intervenes in the short- and long-term control of water and electrolyte balance and of blood pressure. Phylogenetically, ANF appears early, suggesting different functions for this peptide in accordance with each species' environment. Knowledge of the properties of the hormone should provide insights into the pathophysiology of important clinical entities and lead to the development of new pharmaceutical products.     

Mercury in a Greenland ice sheet: evidence of recent input by man

The increased mercury content in a Greenland ice sheet over the last several decades suggests the dissemination of this element about the earth's atmosphere through the activities of man. The mercury content in the atmosphere appears to result primarily from the degassing of the earth's crust. Increased flux may come about as a result of the enhancement of this degassing process through the actions of man.     

Sediment transport in a precambrian ice age: the huronian gowganda formation

The Gowganda Formation of Ontario consists of conglomerates, quartzites, and argillites deposited in a glacial environment. The distribution of varved argillites and silty limestones suggests continental and marine facies, respectively. Pebble and ripple-drift orientations, distribution of limestones, striated pavements, distribution of the underlying Bruce Group, and Huronian quartzite paleocurrents support the conclusion that sediment transport was from north to south.     

Biphasic feeding response in a sea anemone: control by asparagine and glutathione

Two phases of the feeding response in the sea anemone Anthopleura elegantissima are controlled by different chemical activators. Asparagine controls the contraction and bending of tentacles which bring food to the mouth; reduced glutathione controls ingestion of food once it has contacted the mouth. A complete feeding response occurs only when both chemical activators are present.     

Coral reef growth in the galapagos: limitation by sea urchins

The regular echinoid Eucidaris thouarsii is a conspicuous omnivore on coral bottoms in the Galápagos. Unlike Eucidaris in Panama and mainland Ecuador, Galápagos Eucidaris are large and abundant and graze heavily in the open on live corals day and night. These differences are probably due in large part to more intense predation by fishes on mainland compared with island urchin populations. An assessment of coral growth versus coral attrition from grazing shows that Eucidaris interferes with the establishment of pocilloporid reef frame and therefore reduces reef growth in the Galápagos.     

Bacterial growth rate in the sea: direct analysis by thymidine autoradiography

Autoradiography with tritiated thymidine was used to study microbial growth directly in nature. The epiphyte Leucothrix mucor was used since it is a large filamentous bacterium with a characteristic morphology making it recognizable in natural collections. The technique was developed initially with pure cultures. The relation between growth rate and the rate of accumulation of radioactive cells permitted derivation of a constant for use in calculating growth rate in natural material and in two-membered cultures of L. mucor growing epiphytically on pure cultures of marine algae. The growth rate (generation time) in two-membered cultures with the red alga Antithamnion sarniense was 94 minutes under the conditions used. In nature the growth rate of a sample from Iceland was 685 minutes; that of a sample from Long Island Sound was 660 minutes. There was no evidence of preferential growth in the basal portion of bacterial filaments nearest the algal surface. However, filamentous growth in nature, but not in pure or two-membered culture, was nonrandom, growth being clustered in some regions.     

不同采样幅度和间距下压砂地枣树土壤水分的空间变异性研究

为了探明西北地区特有的压砂地枣树土壤水分的空间变异及其尺度效应,本文基于野外试验,选取32m×32 m区域,并在此基础上改变采样幅度和采样间距,基于经典统计学和地统计学理论,研究了不同采样幅度和间距条件下0-50 cm土层土壤含水量的空间分布特征及其空间变异性。结果表明,对于所有5种采样幅度(32m×32 m、28 m×28 m、24 m×24 m、20 m×20 m和16 m×16 m),随土层深度的增加,土壤含水量呈减小的趋势,而变异系数呈增大的趋势,空间变异强度基本表现为弱变异至中等偏弱变异;当采样幅度增大时,土壤含水量的变异系数Cv、块金值C0及变程A均不断增大。对于4 m、8 m和12 m这3种采样间距,当采样间距增大时,土壤含水量的块金值C0不断增大,变程A不断减小,而变异系数Cv不受影响。在不同尺度内,土壤含水量均存在强烈的空间自相关性。各土层土壤含水量在不同采样间距下的空间分布形态相似,多处出现明显的"隆起"与"凹陷",受地形影响显著,并随着采样间距的增大,逐渐平坦化,8 m为较合理的采样间距。     

Ross sea region in the middle miocene: a glimpse into the past

Fossil diatoms and pollen from sea-floor sediments beneath the Ross Ice Shelf indicate that a permanent ice cover was not present in the Ross Sea and that vegetation including angiosperms, gymnosperms, and ferns existed on at least some parts of the largely glaciated Antarctic mainland in the late middle Miocene.     

舟山近海海域夏季上升流时空特征及其与风场的关系

利用2002-2013年期间的卫星遥感海表温度(SST)数据分析了舟山海域夏季上升流的时空特征,并结合同时期的海面风场数据探讨了风对该海域夏季上升流的影响。对多年夏季月平均的SST进行经验正交函数(EOF)分解结果表明,7月份前两个模态方差贡献率分别为71.66%、16.55%,8月份前两个模态方差贡献率分别为87.03%和7.30%,并均通过了显著性检验,舟山近海海域的上升流存在较为明显的年际变化。相关分析显示,经向风速和SST异常存在显著的负相关关系,即夏季盛行的西南风有利于上升流的发展。并且,艾克曼(Ekman)体积输运计算结果表明,舟山海域7、8月份风生上升流的量级分别为3.0×10~(-5)m/s和1.5×10~(-5)m/s,7月上升流显著强于8月,这与8月份观测到的海表显著低温异常相关。     

Alterations in the pattern of amine excretion in man produced by a monoamine oxidase inhibitor

The administration of monoamine oxidase inhibitors produces an increase in the urinary excretion of many amines for which efficient alternate routes of metabolism are not available. These include tryptamine, paratyramine, and a "metatyramine-like" substance. The inhibitors can therefore be used to detect previously unsuspected pathways of amino acid decarboxylation. The finding that the excretions of norepinephrine, epinephrine, 3,4-dihydroxyphenylethylamine, and possible serotonin are not appreciably affected are consistent with previous reports of the existence of alternative metabolic routes.     

Desiccation of the aral sea: a water management disaster in the soviet union

The Aral Sea in the Soviet Union, formerly the world's fourth largest lake in area, is disappearing. Between 1960 and 1987, its level dropped nearly 13 meters, and its area decreased by 40 percent. Recession has resulted from reduced inflow caused primarily by withdrawals of water for irrigation. Severe environmental problems have resulted. The sea could dry to a residual brine lake. Local water use is being improved and schemes to save parts of the sea have been proposed. Nevertheless, preservation of the Aral may require implementation of the controversial project to divert water from western Siberia into the Aral Sea basin.     

Tritium-helium dating in the sargasso sea: a measurement of oxygen utilization rates

The newly developed technique of "tritium-helium dating" has been used to investigate in situ rates of oceanic oxygen utilization. As an example, an apparent oxygen utilization rate of 0.20 +/- 0.02 milliliter per liter of water per year has been obtained for the Subtropical Mode water (18 degrees C water) in the Sargasso Sea.     

Bacterial rhodopsin: evidence for a new type of phototrophy in the sea

Extremely halophilic archaea contain retinal-binding integral membrane proteins called bacteriorhodopsins that function as light-driven proton pumps. So far, bacteriorhodopsins capable of generating a chemiosmotic membrane potential in response to light have been demonstrated only in halophilic archaea. We describe here a type of rhodopsin derived from bacteria that was discovered through genomic analyses of naturally occuring marine bacterioplankton. The bacterial rhodopsin was encoded in the genome of an uncultivated gamma-proteobacterium and shared highest amino acid sequence similarity with archaeal rhodopsins. The protein was functionally expressed in Escherichia coli and bound retinal to form an active, light-driven proton pump. The new rhodopsin exhibited a photochemical reaction cycle with intermediates and kinetics characteristic of archaeal proton-pumping rhodopsins. Our results demonstrate that archaeal-like rhodopsins are broadly distributed among different taxa, including members of the domain Bacteria. Our data also indicate that a previously unsuspected mode of bacterially mediated light-driven energy generation may commonly occur in oceanic surface waters worldwide.     

基于地理探测器和GIS的压砂地砾石空间异质性及其影响因素分析

为探究压砂地不同粒径砾石空间异质性及其影响因素,基于压砂地102个采样点,对不同粒径砾石配比进行了描述性统计,通过半方差函数和全局空间自相关分析等地统计方法分析了压砂地不同粒径砾石的空间变异特征和聚集模式,并进一步利用地理探测器模型识别影响不同粒径砾石占比空间分异的主要影响因子,在此基础之上,选取主要影响因子协同地理加权回归克里格法对不同粒径砾石占比进行可视化,获取其分布特征。结果表明,不同粒径砾石的空间变异系数均大于10%,属中等变异。不同粒径砾石的空间异质比变化范围较大（0.26%~83.48%）,其空间异质性受随机性因素和结构性因素共同影响。空间自相关分析显示各粒径砾石的全局Moran''s I均高于0.674,且Z值均大于1.96,表明不同粒径砾石具有极显著的空间依赖特征,呈聚集性分布。地理探测器模型识别表明压砂地不同粒径砾石的空间分异的解释力由大到小依次为种植年限>坡向>地表粗糙度>坡度>剖面曲率>平面曲率>地表起伏度,种植年限的单因子解释力明显高于其他因子。不同环境条件下压砂地土体中不同粒径砾石空间分布差异明显且呈聚集性分布特征。种植年限、坡向和地表粗糙度是压砂地不同粒径砾石空间分布状况的主要影响因子。     

Pressure regulation in the middle ear cavity of sea lions: a possible mechanism

The mucosa lining the cavity of the middle ear of sea lions contains a complex network of venous channels and sinuses. During dives the pressure within the middle ear may be equalized with that in the external auditory meatus either by the distention or depression of the mucosa due to the presence or absence of blood in the sinuses.