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  • 1
    Publication Date: 2017-05-23
    Description: Extracellular polymeric substances (EPS) are ubiquitous on tidal flats but their impact on sediment erosion has not been fully understood. Laboratory-controlled sediment beds were incubated with Bacillus subtilis for 5, 10, 16 and 22 days before the erosion experiments, to study the temporal and spatial variations in sediment stability caused by the bacterial secreted EPS. We found the bio-sedimentary systems showed different erosional behaviour related to biofilm maturity and EPS distribution. In the first stage (5 days), the bio-sedimentary bed was more easily eroded than the clean sediment. With increasing growth period, bound EPS became more widely distributed over the vertical profile resulting in bed stabilisation. After 22 days, the bound EPS was highly concentrated within a surface biofilm, but a relatively high content also extended to a depth of 5 mm and then decayed sharply with depth. The biofilm increased the critical shear stress of the bed and furthermore, it enabled the bed to withstand threshold conditions for an increased period of time as the biofilm degraded before eroding. After the loss of biofilm protection, the high EPS content in the sub-layers continued to stabilise the sediment (hindered erosion) by binding individual grains, as visualized by electron microscopy. Consequently, the bed strength did not immediately revert to the abiotic condition but progressively adjusted, reflecting the depth profile of the EPS. Our experiments highlight the need to treat the EPS-sediment conditioning as a bed-age associated and depth-dependent variable that should be included in the next generation of sediment transport models.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 2
    Publication Date: 2015-01-16
    Description: The gas-liquid two-phase flow in pelton turbines is very complicated, there are many kinds of bad-behaved flow in pelton turbines. In this paper, CFD numerical simulation for the pelton turbine was conducted using VOF two-phase model. One kind of bad-behaved flow caused by the two jets was captured, and the bad-behaved flow was analysed by torque on buckets. It can be concluded that the angle between the two jets and the value of ratio of runner diameter and jet diameter are important parameters for the bad-behaved flow. Furthermore, the reason why the efficiency of some multi-jet type turbines is very low can be well explained by the analysis of bad-behaved flow. Finally, some suggestions for improvement were also provided in present paper.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 3
    Publication Date: 2015-01-16
    Description: In order to get the accurate hump characteristic curve of a pump turbine in pump mode, three dimensional steady simulations were carried out using SST k-ω turbulence model with cavitation model and without cavitation model under different operation condition points with 19 mm guide vanes opening. A refinement grids were generated to adapt the turbulence model. The results obtained with cavitation model show a better agreement with experiments. The detailed analysis was undertaken to find out the relationship between the cavitation and hump region. It is concluded that the hump characteristic is related with cavitation.
    Print ISSN: 1757-8981
    Electronic ISSN: 1757-899X
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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  • 4
    Publication Date: 2012-06-16
    Description: Active DNA demethylation is an important part of epigenetic regulation in plants and animals. How active DNA demethylation is regulated and its relationship with histone modification patterns are unclear. Here, we report the discovery of IDM1, a regulator of DNA demethylation in Arabidopsis. IDM1 is required for preventing DNA hypermethylation of highly homologous multicopy genes and other repetitive sequences that are normally targeted for active DNA demethylation by Repressor of Silencing 1 and related 5-methylcytosine DNA glycosylases. IDM1 binds methylated DNA at chromatin sites lacking histone H3K4 di- or trimethylation and acetylates H3 to create a chromatin environment permissible for 5-methylcytosine DNA glycosylases to function. Our study reveals how some genes are indicated by multiple epigenetic marks for active DNA demethylation and protection from silencing.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3575687/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3575687/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Qian, Weiqiang -- Miki, Daisuke -- Zhang, Heng -- Liu, Yunhua -- Zhang, Xi -- Tang, Kai -- Kan, Yunchao -- La, Honggui -- Li, Xiaojie -- Li, Shaofang -- Zhu, Xiaohong -- Shi, Xiaobing -- Zhang, Kangling -- Pontes, Olga -- Chen, Xuemei -- Liu, Renyi -- Gong, Zhizhong -- Zhu, Jian-Kang -- R01 GM059138/GM/NIGMS NIH HHS/ -- R01 GM070795/GM/NIGMS NIH HHS/ -- R01GM059138/GM/NIGMS NIH HHS/ -- R01GM070795/GM/NIGMS NIH HHS/ -- New York, N.Y. -- Science. 2012 Jun 15;336(6087):1445-8. doi: 10.1126/science.1219416.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Shanghai Center for Plant Stress Biology and Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes of Biological Sciences, Chinese Academy of Sciences, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22700931" target="_blank"〉PubMed〈/a〉
    Keywords: Acetylation ; Arabidopsis/*genetics/*metabolism ; Arabidopsis Proteins/chemistry/genetics/*metabolism ; Chromatin/metabolism ; DNA Glycosylases/metabolism ; *DNA Methylation ; DNA, Plant/*metabolism ; Gene Silencing ; Genes, Plant ; Histone Acetyltransferases/chemistry/genetics/*metabolism ; Histones/metabolism ; Methylation ; Mutation ; Nuclear Proteins/genetics/metabolism ; Protein Structure, Tertiary ; Transgenes
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2009-03-28
    Description: Similarities in the behavior of diverse animal species that form large groups have motivated attempts to establish general principles governing animal group behavior. It has been difficult, however, to make quantitative measurements of the temporal and spatial behavior of extensive animal groups in the wild, such as bird flocks, fish shoals, and locust swarms. By quantifying the formation processes of vast oceanic fish shoals during spawning, we show that (i) a rapid transition from disordered to highly synchronized behavior occurs as population density reaches a critical value; (ii) organized group migration occurs after this transition; and (iii) small sets of leaders significantly influence the actions of much larger groups. Each of these findings confirms general theoretical predictions believed to apply in nature irrespective of animal species.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Makris, Nicholas C -- Ratilal, Purnima -- Jagannathan, Srinivasan -- Gong, Zheng -- Andrews, Mark -- Bertsatos, Ioannis -- Godo, Olav Rune -- Nero, Redwood W -- Jech, J Michael -- New York, N.Y. -- Science. 2009 Mar 27;323(5922):1734-7. doi: 10.1126/science.1169441.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. makris@mit.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19325116" target="_blank"〉PubMed〈/a〉
    Keywords: Animal Migration ; Animals ; Atlantic Ocean ; *Behavior, Animal ; Ecosystem ; Fishes/*physiology ; Population Density ; Reproduction ; Spatial Behavior ; *Swimming ; Time Factors
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2019
    Description: Abstract We develop a process‐based model to simulate the geomorphodynamic evolution of tidal channels, considering hydrodynamics, flow‐induced bank erosion, gravity‐induced bank collapse, and sediment dynamics. A stress‐deformation analysis and the Mohr‐Coulomb criterion, calibrated through previous laboratory experiments, are included in a model simulating bank collapse. Results show that collapsed bank soil plays a primary role in the dynamics of bank retreat. For bank collapse with small bank height, tensile failure in the middle of the bank (stage I), tensile failure on the bank top (stage II) and sectional cracking from bank top to the toe (stage III) are present sequentially before bank collapse occurs. A significant linear relation is observed between bank height and the contribution of bank collapse to bank retreat. Contrary to flow‐induced bank erosion, bank collapse prevents further widening since the collapsed bank soil protects the bank from direct bank erosion. The bank profile is linear or slightly convex and the planimetric shape of tidal channels (gradually decreasing in width landward) is similar when approaching equilibrium, regardless of the consideration of bank erosion and collapse. Moreover, the simulated width‐to‐depth ratio in all runs is comparable with observations from the Venice Lagoon. This indicates that the equilibrium configuration of tidal channels depends on hydrodynamic conditions and sediment properties, while bank erosion and collapse greatly affect the transient behaviour (before equilibrium) of the tidal channels. Overall, this contribution highlights the importance of collapsed bank soil in investigating tidal channel morphodynamics using a combined perspective of geotechnics and soil mechanics.
    Print ISSN: 0043-1397
    Electronic ISSN: 1944-7973
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 7
    Publication Date: 2010-10-23
    Description: Appropriate preferences for light or dark conditions can be crucial for an animal's survival. Innate light preferences are not static in some animals, including the fruit fly Drosophila melanogaster, which prefers darkness in the feeding larval stage but prefers light in adulthood. To elucidate the neural circuit underlying light preference, we examined the neurons involved in larval phototactic behavior by regulating neuronal functions. Modulating activity of two pairs of isomorphic neurons in the central brain switched the larval light preference between photophobic and photophilic. These neurons were found to be immediately downstream of pdf-expressing lateral neurons, which are innervated by larval photoreceptors. Our results revealed a neural mechanism that could enable the adjustment of animals' response strategies to environmental stimuli according to biological needs.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gong, Zhefeng -- Liu, Jiangqu -- Guo, Chao -- Zhou, Yanqiong -- Teng, Yan -- Liu, Li -- New York, N.Y. -- Science. 2010 Oct 22;330(6003):499-502. doi: 10.1126/science.1195993.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, People's Republic of China. zfgong@moon.ibp.ac.cn〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20966250" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Behavior, Animal/*radiation effects ; Brain/cytology/physiology ; Drosophila melanogaster/cytology/growth & development/*radiation effects ; Green Fluorescent Proteins ; Larva/physiology/radiation effects ; *Light ; Neural Pathways ; Neurons/*physiology
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 8
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    Nature Publishing Group (NPG)
    Publication Date: 2015-01-09
    Description: 〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Gong, Zhaohui -- England -- Nature. 2015 Jan 8;517(7533):145. doi: 10.1038/517145c.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Ningbo University School of Medicine, Ningbo, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/25567273" target="_blank"〉PubMed〈/a〉
    Keywords: Air Pollution/adverse effects/*prevention & control ; China ; Climate Change ; Congresses as Topic ; Humans ; Public Health ; Time Factors
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 9
    Publication Date: 2016-03-05
    Description: Observing marine mammal (MM) populations continuously in time and space over the immense ocean areas they inhabit is challenging but essential for gathering an unambiguous record of their distribution, as well as understanding their behaviour and interaction with prey species. Here we use passive ocean acoustic waveguide remote sensing (POAWRS) in an important North Atlantic feeding ground to instantaneously detect, localize and classify MM vocalizations from diverse species over an approximately 100,000 km(2) region. More than eight species of vocal MMs are found to spatially converge on fish spawning areas containing massive densely populated herring shoals at night-time and diffuse herring distributions during daytime. We find the vocal MMs divide the enormous fish prey field into species-specific foraging areas with varying degrees of spatial overlap, maintained for at least two weeks of the herring spawning period. The recorded vocalization rates are diel (24 h)-dependent for all MM species, with some significantly more vocal at night and others more vocal during the day. The four key baleen whale species of the region: fin, humpback, blue and minke have vocalization rate trends that are highly correlated to trends in fish shoaling density and to each other over the diel cycle. These results reveal the temporospatial dynamics of combined multi-species MM foraging activities in the vicinity of an extensive fish prey field that forms a massive ecological hotspot, and would be unattainable with conventional methodologies. Understanding MM behaviour and distributions is essential for management of marine ecosystems and for accessing anthropogenic impacts on these protected marine species.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Wang, Delin -- Garcia, Heriberto -- Huang, Wei -- Tran, Duong D -- Jain, Ankita D -- Yi, Dong Hoon -- Gong, Zheng -- Jech, J Michael -- Godo, Olav Rune -- Makris, Nicholas C -- Ratilal, Purnima -- England -- Nature. 2016 Mar 17;531(7594):366-70. doi: 10.1038/nature16960. Epub 2016 Mar 2.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Laboratory for Ocean Acoustics and Ecosystem Sensing, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 02115, USA. ; Laboratory for Undersea Remote Sensing, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139, USA. ; Northeast Fisheries Science Center, 166 Water Street, Woods Hole, Massachusetts 02543, USA. ; Institute of Marine Research, Post Office Box 1870, Nordnes, N-5817 Bergen, Norway.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/26934221" target="_blank"〉PubMed〈/a〉
    Keywords: Acoustics ; Animals ; Aquatic Organisms/*physiology ; Atlantic Ocean ; Diet/veterinary ; Ecosystem ; *Feeding Behavior ; Fishes/*physiology ; Male ; Mammals/*physiology ; *Predatory Behavior ; Time Factors ; *Vocalization, Animal ; Whales/physiology
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 10
    Publication Date: 2011-11-25
    Description: On the basis of geophysical observations, cosmochemical constraints, and high-pressure experimental data, the Earth's liquid outer core consists of mainly liquid iron alloyed with about ten per cent (by weight) of light elements. Although the concentrations of the light elements are small, they nevertheless affect the Earth's core: its rate of cooling, the growth of the inner core, the dynamics of core convection, and the evolution of the geodynamo. Several light elements-including sulphur, oxygen, silicon, carbon and hydrogen-have been suggested, but the precise identity of the light elements in the Earth's core is still unclear. Oxygen has been proposed as a major light element in the core on the basis of cosmochemical arguments and chemical reactions during accretion. Its presence in the core has direct implications for Earth accretion conditions of oxidation state, pressure and temperature. Here we report new shockwave data in the Fe-S-O system that are directly applicable to the outer core. The data include both density and sound velocity measurements, which we compare with the observed density and velocity profiles of the liquid outer core. The results show that we can rule out oxygen as a major light element in the liquid outer core because adding oxygen into liquid iron would not reproduce simultaneously the observed density and sound velocity profiles of the outer core. An oxygen-depleted core would imply a more reduced environment during early Earth accretion.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Huang, Haijun -- Fei, Yingwei -- Cai, Lingcang -- Jing, Fuqian -- Hu, Xiaojun -- Xie, Hongsen -- Zhang, Lianmeng -- Gong, Zizheng -- England -- Nature. 2011 Nov 23;479(7374):513-6. doi: 10.1038/nature10621.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉School of Sciences, Wuhan University of Technology, Wuhan, Hubei 430070, China.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22113693" target="_blank"〉PubMed〈/a〉
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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