Interaction of laminar far wake with a free surface

Wave disturbances caused by the uniform translatory motion of a submerged body on or beneath the free surface of a viscous fluid are investigated analytically. The submerged body is idealized as an Oseenlet or an Oseen doublet, and exact solutions in closed integral forms are obtained. Based on these exact solutions, asymptotic representations of the wave amplitude for large Reynolds numbers based on the deep-water wavelength at large distances downstream of the body are derived. The results obtained show explicitly the effect of the laminar wake on the amplitude and the phase of the surface waves thus created. ©1996 American Institute of Physics.published_or_final_versio

Effects of test conditions on shear behaviour of composite soil

Test conditions, such as shearing rate and normal stress, have been long recognised as influencing the measured shear strength of clays and sands. However, their influence on composite soils, which have a wide range of particle sizes, has attracted much less attention from researchers. In this study, a total of 35 direct shear tests at different shearing rates under different normal stresses were conducted on specimens prepared by mixing different proportions of kaolin and glass beads. The changes in volume and water content of sheared specimens and the mesostructure of shear surfaces were studied. The results reveal a positive correlation between volume change and deviation of water content between the shear zone and outer zones, suggesting that the shear-induced volume change occurred primarily in the shear zones. Moreover, high normal stress and low shearing rate produced a relatively small void ratio in the shear zones, facilitating volumetric contraction of the specimen and the development of polished and evenly slickensided shear surfaces. In addition, the residual friction angle of the specimens tested was found to decrease with the increase in normal stress. The high shearing rate caused an increase in residual strength in specimens with low fines fraction, and reduced it in specimens with high fines fraction.published_or_final_versio

Widened pulse pressure is a potential risk factor for significant cognitive impairment among community-dwelling Chinese younger old people

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Team 4 VCU: Ram Resources: Helping Faculty Help Students

The Ram Resources Project seeks to provide students with an environment that encourages their well-being by connecting them with resources needed to succeed in their academic career at VCU. Ram Resources will help reduce the detrimental impact of the number-one problem affecting students’ academic performance: stress. Faculty are uniquely situated both to recognize changes in students’ behavior and to assist students with improving their well-being. Beginning with New Faculty Orientation, Ram Resources will educate faculty about resources for well-being available to students. By creating a brochure, a website, and establishing a program of faculty ambassadors to familiarize faculty with the resources available to identify the warning signs of stress, the team proposes to help faculty help students

Solitons and 2 D vortex dynamics

Session AI: Vortex Dynamics, abstract no. AI.01published_or_final_versio

Evidence of Airborne Transmission of the Severe Acute Respiratory Syndrome Virus

BACKGROUND: There is uncertainty about the mode of transmission of the severe acute respiratory syndrome (SARS) virus. We analyzed the temporal and spatial distributions of cases in a large community outbreak of SARS in Hong Kong and examined the correlation of these data with the three-dimensional spread of a virus-laden aerosol plume that was modeled using studies of airflow dynamics. METHODS: We determined the distribution of the initial 187 cases of SARS in the Amoy Gardens housing complex in 2003 according to the date of onset and location of residence. We then studied the association between the location (building, floor, and direction the apartment unit faced) and the probability of infection using logistic regression. The spread of the airborne, virus-laden aerosols generated by the index patient was modeled with the use of airflow-dynamics studies, including studies performed with the use of computational fluid-dynamics and multizone modeling. RESULTS: The curves of the epidemic suggested a common source of the outbreak. All but 5 patients lived in seven buildings (A to G), and the index patient and more than half the other patients with SARS (99 patients) lived in building E. Residents of the floors at the middle and upper levels in building E were at a significantly higher risk than residents on lower floors; this finding is consistent with a rising plume of contaminated warm air in the air shaft generated from a middle-level apartment unit. The risks for the different units matched the virus concentrations predicted with the use of multizone modeling. The distribution of risk in buildings B, C, and D corresponded well with the three-dimensional spread of virus-laden aerosols predicted with the use of computational fluid-dynamics modeling. CONCLUSIONS: Airborne spread of the virus appears to explain this large community outbreak of SARS, and future efforts at prevention and control must take into consideration the potential for airborne spread of this virus. Copyright © 2004 Massachusetts Medical Society.published_or_final_versio

Influence of Atomic Surface Structure on the Activity of Ag for the Electrochemical Reduction of CO 2 to CO

The present work was undertaken to elucidate the facet-dependent activity of Ag for the electrochemical reduction of CO to CO. To this end, CO reduction was investigated over Ag thin films with (111), (100), and (110) orientations prepared via epitaxial growth on single-crystal Si wafers with the same crystallographic orientations. This preparation technique yielded larger area electrodes than can be achieved using single-crystals, which enabled the electrocatalytic activity of the corresponding Ag surfaces to be quantified in the Tafel regime. The Ag(110) thin films exhibited higher CO evolution activity compared to the Ag(111) and Ag(100) thin films, consistent with previous single-crystal studies. Density functional theory calculations suggest that CO reduction to CO is strongly facet-dependent, and that steps are more active than highly coordinated terraces. This is the result of both a higher binding energy of the key intermediate COOH as well as an enhanced double-layer electric field stabilization over undercoordinated surface atoms located at step edge defects. As a consequence, step edge defects likely dominate the CO reduction activity observed over the Ag(111) and Ag(100) thin films. The higher activity observed over the Ag(110) thin film is then related to the larger density of undercoordinated sites compared to the Ag(111) and Ag(100) thin films. Our conclusion that undercoordinated sites dominate the CO reduction activity observed over close-packed surfaces highlights the need to consider the contribution of such defects in studies of single-crystal electrodes. 2 2 2 2

Checkpoints are blind to replication restart and recombination intermediates that result in gross chromosomal rearrangements

Replication fork inactivation can be overcome by homologous recombination, but this can cause gross chromosomal rearrangements that subsequently missegregate at mitosis, driving further chromosome instability. It is unclear when the chromosome rearrangements are generated and whether individual replication problems or the resulting recombination intermediates delay the cell cycle. Here we have investigated checkpoint activation during HR-dependent replication restart using a site-specific replication fork-arrest system. Analysis during a single cell cycle shows that HR-dependent replication intermediates arise in S phase, shortly after replication arrest, and are resolved into acentric and dicentric chromosomes in G2. Despite this, cells progress into mitosis without delay. Neither the DNA damage nor the intra-S phase checkpoints are activated in the first cell cycle, demonstrating that these checkpoints are blind to replication and recombination intermediates as well as to rearranged chromosomes. The dicentrics form anaphase bridges that subsequently break, inducing checkpoint activation in the second cell cycle

From Memorization to Discovery in American Accounting Education

由厦门大学会计发展研究中心提供的第四届会计与财务问题国际研讨会——会计教育改革与发展论文集中的第一部分：会计教育一般0