723 research outputs found

    Electrothermal flow in Dielectrophoresis of Single-Walled Carbon Nanotubes

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    We theoretically investigate the impact of the electrothermal flow on the dielectrophoretic separation of single-walled carbon nanotubes (SWNT). The electrothermal flow is observed to control the motions of semiconducting SWNTs in a sizeable domain near the electrodes under typical experimental conditions, therefore helping the dielectrophoretic force to attract semiconducting SWNTs in a broader range. Moreover, with the increase of the surfactant concentration, the electrothermal flow is enhanced, and with the change of frequency, the pattern of the electrothermal flow changes. It is shown that under some typical experimental conditions of dielectrophoresis separation of SWNTs, the electrothermal flow is a dominating factor in determining the motion of SWNTs.Comment: 5 pages, 4 figures, Submitted to PR

    Inhibitors of SARS-CoV entry--identification using an internally-controlled dual envelope pseudovirion assay.

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    Severe acute respiratory syndrome-associated coronavirus (SARS-CoV) emerged as the causal agent of an endemic atypical pneumonia, infecting thousands of people worldwide. Although a number of promising potential vaccines and therapeutic agents for SARS-CoV have been described, no effective antiviral drug against SARS-CoV is currently available. The intricate, sequential nature of the viral entry process provides multiple valid targets for drug development. Here, we describe a rapid and safe cell-based high-throughput screening system, dual envelope pseudovirion (DEP) assay, for specifically screening inhibitors of viral entry. The assay system employs a novel dual envelope strategy, using lentiviral pseudovirions as targets whose entry is driven by the SARS-CoV Spike glycoprotein. A second, unrelated viral envelope is used as an internal control to reduce the number of false positives. As an example of the power of this assay a class of inhibitors is reported with the potential to inhibit SARS-CoV at two steps of the replication cycle, viral entry and particle assembly. This assay system can be easily adapted to screen entry inhibitors against other viruses with the careful selection of matching partner virus envelopes

    The Feasibility of Road User Fees and Other Alternative Sources of Transportation Funding

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    The nation faces an approaching crisis in transportation funding. This is a critical issue that is both relevant and essential to public administration. It affects all levels of government and extends across the nation. Rapidly declining sources of transportation funding pose short-term and long-term challenges for politicians, public administrators, and everyday citizens. In the face of inadequate revenues, new forms of funding are necessary to keep the transportation system solvent. This paper will briefly outline the history of transportation funding that created this problem and examine various proposed solutions. It will focus specifically on the emerging theory of road user fees. The philosophical principles of road user fees will be discussed along with specific policy proposals that embody them such as the vehicle miles traveled fee (VMT-F). The paper will assess both the strengths and weaknesses of the VMT-F along with various other alternative methods of transportation funding. The paper will conclude with recommendations for further research that may help secure adequate transportation funding sources for the future

    Beam dynamics for the sc cw heavy ion linac at GSI

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    For future experiments with heavy ions near the coulomb barrier within the SHE (super-heavy elements) research project a multi-stage R&D program of GSI, HIM and IAP is currently in progress. It aims at developing a superconducting (sc) continuous wave (cw) LINAC with multiple CH cavities as key components downstream the High Charge Injector (HLI) at GSI. The beam dynamics concept is based on EQUUS (equidistant multigap structure) constant-beta cavities. Advantages of its periodicity are a high simulation accuracy, easy manufacturing and tuning with minimized costs as well as a straightforward energy variation. The next milestone will be a full performance beam test of the first LINAC section, comprising two solenoids and a 15-gap CH cavity inside a cryostat (Demonstrator)

    Some solubility criteria in factorised groups

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    This paper has been published in Bulletin of the Australian Mathematical Society, 86(1):22-28 (2012). Copyright 2012 by Australian Mathematical Publishing Association Inc and Cambridge University Press Journals. The final publication is available at http://journals.cambridge.org/abstract_S0004972711003418In this paper, solubility of groups factorised as a product of two subgroups which are connected by certain permutability properties is studied.The research of the second and the third authors has been supported by the grant MTM2010-19938-C03-01 from the Ministerio de Ciencia e Innovacion (Spanish government).http://dx.doi.org/10.1017/S0004972711003418Asaad, M.; Ballester Bolinches, A.; Esteban Romero, R. (2012). Some solubility criteria in factorised groups. Bulletin of the Australian Mathematical Society. (86). doi:10.1017/S0004972711003418S8

    In My View

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    Results of the MTLRS-1 upgrade

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    In this report, the results of the upgrade of the German Modular Transportable Laser Ranging System MTLRS-1 are summarized. A short description of the new components and their influence on the system accuracy is given. It is shown, that the single shot accuracy of the MTLRS-1 has been improved from 5 cm to 1 cm

    Missouri National Recreational River, Natural Resource Condition Assessment

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    Executive Summary As a unit in the National Park Service (NPS), Missouri National Recreational River (MNRR) is responsible for the management and conservation of natural resources within its boundaries. This mandate is supported by the National Park Service Organic Act of 1916, which directs the NPS to: conserve the scenery and natural and historic objects and the wildlife therein and to provide for the enjoyment of the same in such a manner and by such means as will leave them unimpaired for the enjoyment of future generations. In 2003, NPS Water Resources Division received funding through the Natural Resource Challenge Program to systematically assess watershed resource conditions in NPS units, establishing the Watershed Condition Assessment Program. This program, now titled the Natural Resource Condition Assessment (NRCA) Program, aims to provide documentation about the current conditions of important park resources through a spatially explicit, multi-disciplinary synthesis of existing scientific data and knowledge. Findings from the NRCA, including the report and accompanying map products, will help MNRR managers to: develop near-term management priorities, engage in watershed or landscape scale partnership and education efforts, conduct park planning (e.g. Resource Stewardship Strategy), report program performance (e.g. Department of the Interior’s Strategic Plan ―land health goals, Government Performance and Results Act). Specific project expectations and outcomes for the MNRR NRCA are listed in Chapter 3. For the purpose of this NRCA, NPS staff identified key resources that are referred to as ―components‖ in the project framework and throughout the assessment. The components selected include natural resources and processes that are currently of the greatest concern to park management at MNRR. The final project framework contains nine resource components, along with measures, stressors, and reference conditions for each. This study involved reviewing existing literature and data for each of the components in the framework and, where appropriate, analyzing the data in order to provide summaries or to create new spatial or statistical representations. After gathering data regarding current condition of component measures, those data were compared to reference conditions (when possible) and a qualitative statement of condition was developed. The discussions in Chapter 4 represent a comprehensive summary of available information regarding the current condition of these resources. These discussions represent not only the most current published literature, but also unpublished park information and, most importantly, the perspectives of park experts. Nearly every component in MNRR is affected by the altered flow regime from the post-dam Missouri River and, with that, the conditions of most park resources (as indicated by the measures defined in the project framework) are of moderate or significant concern. These condition designations are largely a product of the ―pre-dam‖ reference condition assigned to nearly every MNRR component. When comparing the current condition of a resource that has been drastically altered by damming to its pre-dam condition, it is almost always worse off today. However, while the Missouri River ecosystem has endured large changes since dam construction, there are several individual components that are recovering and doing well with the given circumstances. Differing uses and interests of the Missouri River (e.g. preservation, recreation, electricity generation, navigation, etc.) further complicate MNRR’s ability to restore the Missouri River to its pre-dam condition. However, several components ( e.g. flow regime, aquatic and terrestrial habitats, erosional and depositional processes) are drivers of the entire ecosystem, and restoration of these components would have a cascading effect on the entire ecosystem. Overall, the Missouri River ecosystem is complex and while several components are considered to be of moderate or significant concern, their actual condition (when considering the the condition of the Missouri River ecosystem) is often times of lower concern

    The nature of Ordovician limestone-marl alternations in the Oslo-Asker District (Norway):witnesses of primary glacio-eustasy or diagenetic rhythms?

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    Ordovician limestone-marl alternations in the Oslo-Asker District have been interpreted as signaling glacio-eustatic lowstands, which would support a prolonged “Early Palaeozoic Icehouse”. However, these rhythmites could alternatively reflect differential diagenesis, without sedimentary trigger. Here, we test both hypotheses through one Darriwilian and three Katian sections. Our methodology consists of a bed-by-bed analysis of palynological (chitinozoan) and geochemical (XRF) data, to evaluate whether the limestone/marl couplets reflect an original cyclic signal. The results reveal similar palynomorph assemblages in limestones and marls. Exceptions, which could be interpreted as reflecting palaeoclimatological fluctuations, exist at the species level: Ancyrochitina bornholmensis seems to be more abundant in the marl samples from the lower Frognerkilen Formation on Nakkholmen Island. However, these rare cases where chitinozoans differ between limestone/marl facies are deemed insufficient for the identification of original cyclicity. The geochemical data show a near-perfect correlation between insoluble elements in the limestone and the marls, which indicates a similar composition of the potential precursor sediment, also in the Frognerkilen Formation. This is consistent with the palynological data. Although an original cyclic pattern could still be recorded by other, uninvestigated parameters, our palaeontological and geochemical data combined do not support the presence of such a signal

    Comparative Live-Cell Imaging Analyses of SPA-2, BUD-6 and BNI-1 in Neurospora crassa Reveal Novel Features of the Filamentous Fungal Polarisome

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    A key multiprotein complex involved in regulating the actin cytoskeleton and secretory machinery required for polarized growth in fungi, is the polarisome. Recognized core constituents in budding yeast are the proteins Spa2, Pea2, Aip3/Bud6, and the key effector Bni1. Multicellular fungi display a more complex polarized morphogenesis than yeasts, suggesting that the filamentous fungal polarisome might fulfill additional functions. In this study, we compared the subcellular organization and dynamics of the putative polarisome components BUD-6 and BNI-1 with those of the bona fide polarisome marker SPA-2 at various developmental stages of Neurospora crassa. All three proteins exhibited a yeast-like polarisome configuration during polarized germ tube growth, cell fusion, septal pore plugging and tip repolarization. However, the localization patterns of all three proteins showed spatiotemporally distinct characteristics during the establishment of new polar axes, septum formation and cytokinesis, and maintained hyphal tip growth. Most notably, in vegetative hyphal tips BUD-6 accumulated as a subapical cloud excluded from the Spitzenkörper (Spk), whereas BNI-1 and SPA-2 partially colocalized with the Spk and the tip apex. Novel roles during septal plugging and cytokinesis, connected to the reinitiation of tip growth upon physical injury and conidial maturation, were identified for BUD-6 and BNI-1, respectively. Phenotypic analyses of gene deletion mutants revealed additional functions for BUD-6 and BNI-1 in cell fusion regulation, and the maintenance of Spk integrity. Considered together, our findings reveal novel polarisome-independent functions of BUD-6 and BNI-1 in Neurospora, but also suggest that all three proteins cooperate at plugged septal pores, and their complex arrangement within the apical dome of mature hypha might represent a novel aspect of filamentous fungal polarisome architecture
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