Order parameter of MgB_2: a fully gapped superconductor

We have measured the low-temperature specific heat C(T) for polycrystalline MgB_2 prepared by high pressure synthesis. C(T) below 10 K vanishes exponentially, which unambiguously indicates a fully opened superconducting energy gap. However, this gap is found to be too small to account for Tc of MgB_2. Together with the small specific heat jump DeltaC/gamma_nTc=1.13, scenarios like anisotropic s-wave or multi-component order parameter are called for. The magnetic field dependence of gamma(H) is neither linear for a fully gapped s-wave superconductor nor H^1/2 for nodal order parameter. It seems that this intriguing behavior of gamma(H) is associated with the intrinsic electronic properties other than flux pinning.Comment: 7 pages, 5 figures; revised text and figures; references updated, Phys. Rev. Lett., in pres

Consolidated automated support system (CASS) efficiency and allocation cost improvement

In this research project, we provide a method in which we incorporated a nonlinear model to allocate consolidated automated support system (CASS) stations utilizing real demand. In reviewing available literature, we frame the allocation of CASS stations as a problem of discrete capacity allocation with stochastic demand, and note that similar problems exist in the allocation of other types of service capacity (e.g., hospital beds). We employed a nonlinear model to present a better method for allocation. Currently, NAVAIR PMA 260 uses an algebraic formula to determine CASS station allocation. The nonlinear model takes into account factors that the algebraic formula does not, such as aircraft readiness and CASS station utilization. With the model, we generated an optimized allocation of CASS stations based on average demand from aircraft maintenance action forms received at a Fleet Readiness Center over a given period of time. Then, we demonstrate that the optimized allocation can account for monthly, non-stationary demand inputs, as potentially seen in a fleet response plan. Compared to the current allocation of the Fleet Readiness Center analyzed, the optimized allocation improves CASS station utilization rates with a decreased overall number of CASS stations, without an adverse change in aircraft readiness.http://archive.org/details/consolidatedutom1094539003Lieutenant Commander, United States NavyLieutenant, United States NavyApproved for public release; distribution is unlimited

Rebuilding the Brookhaven high flux beam reactor: A feasibility study

After nearly thirty years of operation, Brookhaven`s High Flux Beam Reactor (HFBR) is still one of the world`s premier steady-state neutron sources. A major center for condensed matter studies, it currently supports fifteen separate beamlines conducting research in fields as diverse as crystallography, solid-state, nuclear and surface physics, polymer physics and structural biology and will very likely be able to do so for perhaps another decade. But beyond that point the HFBR will be running on borrowed time. Unless appropriate remedial action is taken, progressive radiation-induced embrittlement problems will eventually shut it down. Recognizing the HFBR`s value as a national scientific resource, members of the Laboratory`s scientific and reactor operations staffs began earlier this year to consider what could be done both to extend its useful life and to assure that it continues to provide state-of-the-art research facilities for the scientific community. This report summarizes the findings of that study. It addresses two basic issues: (i) identification and replacement of lifetime-limiting components and (ii) modifications and additions that could expand and enhance the reactor`s research capabilities

Characterization of streams and rivers in the Minnesota River Basin Critical Observatory: water chemistry and biological field collections, 2013-2016

see readme file, 'Readme_MRB_dataset.txt'This dataset was collected to inform the Water, Sustainability and Climate Minnesota River Basin Observatory, and was supported by the National Science Foundation under Grant No. 1209402 Water, Sustainability and Climate (WSC) – Category 2, Collaborative: Climate and human dynamics as amplifiers of natural change: a framework for vulnerability assessment and mitigation planning. The dataset contains point locations, watershed areas and water quality information for 231 ditch, stream, river and wetland sites located in the Le Sueur River, Chippewa River, Cottonwood River, Cannon River, Wantonwan River and Blue Earth River basins of Minnesota. Study sites ranged in size from 1st order ditches and streams to an 8th order river. Each of these sites was sampled at least once between 2013-2016 (most sites were sampled multiple times) for one or more of the following parameters: 1) water chemistry (total dissolved nitrogen, nitrate-N, nitrite-N, ammonium-N, particulate nitrogen, soluble reactive phosphorus, total dissolved phosphorus, particulate phosphorus, total phosphorus, dissolved organic carbon, dissolved inorganic carbon, particulate carbon, chlorophyll a, total suspended solids, volatile suspended solids, delta-H-2 and delta-O-18 stable isotopes of site water, specific UV absorbance (SUVA) of site water, fluorescence index (FI) of site water); 2) stable isotopes (delta-C-13, delta-N-15, delta-H-2) of invertebrate consumers, particulate carbon and potential food sources; 3) denitrification rates and characteristics of benthic sediment in agricultural drainage ditches; and 4) stream discharge. This dataset also includes spatial data files containing study site locations and watershed areas delineated for each site.National Science Foundation, Grant No. 1209402 Water, Sustainability and Climate (WSC) - Category 2, Collaborative: Climate and human dynamics as amplifiers of natural change: a framework for vulnerability assessment and mitigation planning.National Science Foundation, Grant EAR-1415206 Science, Engineering and Education for Sustainability (SEES) Fellows: Leveraging the waterscape to increase agricultural landscape sustainabilityMinnesota Department of Agriculture, Grant No. 92036, Measuring and modeling watershed phosphorus loss and transport for improved management of agricultural landscapes. Project dollars provided by the Clean Water Fund (from the Clean Water, Land and Legacy Amendment)