66 research outputs found
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Pyrochemical Glovebox Line Replacement and Modernization Effort at Los Alamos National Laboratory Plutonium Facility.
Los Alamos National Laboratory (LANL), as part of the stockpile stewardship mission, is developing the capability to manufacture replacement pits for the United States nuclear weapon stockpile. Part of this effort requires that the various manufacturing activities formerly performed at the Rocky Flats be reconstructed at LANL, modernized to improve operation, and re-certified for pit production. Part of this effort requires that new pyrochemical metal production facilities be installed in TA-55 to replace existing outdated equipment. The purpose of this effort is design, build/procure, assemble, cold test, and support installation activities for ten pyrochemical processing gloveboxes and processing support equipment for insertion into a selected PF-4 laboratory. Eight of the gloveboxes will be connected to a common trolley tunnel with a state-of-the-art automated transport system that can access each glovebox. Five of those gloveboxes will be designed to accommodate standard water-cooled pyrochemical processing furnaces with appropriate lift mechanisms for handling the furnace products and processing hardware. Another glovebox will be designed to accommodate an improved breaking press that will be designed/procured to break alpha metal up to a thickness of l-inch, eliminate introduction of hydraulic oil to the glovebox environment, provide appropriate shielding for prevention of glovebox damage due to shrapnel projectiles, and use interchangeable impact tools in order to be able to process both contaminated and clean metals with the same machine. In addition, a storage glovebox and a distillation glovebox (already developed) will be attached to the transport system. Two other gloveboxes, one accommodating two casting furnaces and another storage glovebox, will be installed in the laboratory independent of the transport system. A transfer system (trolley) will be incorporated to handle material flow between the pyrochemical furnace gloveboxes, the press glovebox, the storage glovebox, and the distillation glovebox. The trolley will be very simple to operate, able to accommodate at least 50 pounds, require minimal maintenance, and be able to be requested and operated fiom any of the glovebox locations on the line. The transfer system will be capable of discharging its load in some manner through the open door to the entrance of each of the gloveboxes on the line. This may be an automatic function with manual selection for unusual loads or a completely manual operation. An existing commercial or otherwise proven system will be used if possible to minimize the design and test time needed for the system. Two commercial systems examined so far are the Montrac monorail type system available from Montech Incorporated and the Linear Synchronous Motor system available from MagneMotion Inc. Work to be completed during FY02 includes glovebox design, transport system industry research, demonstration of selected commercial transport systems, transport system conceptual design, metal breaking press conceptual design, and glovebox furnace lift mechanism design. Glovebox fabrication/procurement, material transport system procurement, press procurement, lift mechanism procurement, system assembly and staging, system testing, assistance in installing the system into TA-55, assistance with NMT configuration management approvals, and shakeout testing of the system is scheduled for FY03 and FY04. The goal is to have a fully functioning and modernized pyrochemical processing line in PF-4 ready for processing sometime in the first or second quarter of FY04
Multiwavelength Observations of A0620-00 in Quiescence
[Abridged.] We present multiwavelength observations of the black hole binary
system, A0620-00. Using the Cosmic Origins Spectrograph on the Hubble Space
Telescope, we have obtained the first FUV spectrum of A0620-00. The observed
spectrum is flat in the FUV and very faint (with continuum fluxes \simeq 1e -
17 ergs/cm^2/s/A). We compiled the dereddened, broadband spectral energy
distribution of A0620-00 and compared it to previous SEDs as well as
theoretical models. The SEDs show that the source varies at all wavelengths for
which we have multiple samples. Contrary to previous observations, the
optical-UV spectrum does not continue to drop to shorter wavelengths, but
instead shows a recovery and an increasingly blue spectrum in the FUV. We
created an optical-UV spectrum of A0620-00 with the donor star contribution
removed. The non-stellar spectrum peaks at \simeq3000 {\deg}A. The peak can be
fit with a T=10,000 K blackbody with a small emitting area, probably
originating in the hot spot where the accretion stream impacts the outer disk.
However, one or more components in addition to the blackbody are needed to fit
the FUV upturn and the red optical fluxes in the optical-UV spectrum. By
comparing the mass accretion rate determined from the hot spot luminosity to
the mean accretion rate inferred from the outburst history, we find that the
latter is an order of magnitude smaller than the former, indicating that
\sim90% of the accreted mass must be lost from the system if the predictions of
the disk instability model and the estimated interoutburst interval are
correct. The mass accretion rate at the hot spot is 10^5 the accretion rate at
the black hole inferred from the X-ray luminosity. To reconcile these requires
that outflows carry away virtually all of the accreted mass, a very low rate of
mass transfer from the outer cold disk into the inner hot region, and/or
radiatively inefficient accretion.Comment: ApJ, accepte
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Ozone, aerosol, potential vorticity, and trace gas trends observed at highâlatitudes over North America from February to May 2000
Ozone (O3) and aerosol scattering ratio profiles were obtained from airborne lidar measurements on thirtyâeight flights over seven deployments covering the latitudes of 40°â85°N between 4 February and 23 May 2000 as part of the Tropospheric Ozone Production about the Spring Equinox (TOPSE) field experiment. Each deployment started from Broomfield, Colorado, with bases in Churchill, Canada, and on most deployments, Thule Air Base, Greenland. Nadir and zenith lidar O3 measurements were combined with in situ O3 measurements to produce vertically continuous O3 profiles from near the surface to above the tropopause. Potential vorticity (PV) distributions along the flight track were obtained from several different meteorological analyses. Ozone, aerosol, and PV distributions were used together to identify the presence of pollution plumes and stratospheric intrusions. Ozone was found to increase in the middle free troposphere (4â6 km) at high latitudes (60°â85°N) by an average of 4.6 ppbv/mo (parts per billion by volume per month) from about 54 ppbv in early February to over 72 ppbv in midâMay. The average aerosol scattering ratios at 1064 nm in the same region increased rapidly at an average rate of 0.36/mo from about 0.38 to over 1.7. Ozone and aerosol scattering were highly correlated over the entire field experiment, and PV and beryllium (7Be) showed no significant positive trend over the same period. The primary cause of the observed O3 increase in the mid troposphere at high latitudes was determined to be the photochemical production of O3 in pollution plumes with less than 20% of the increase from stratosphericallyâderived O3
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The total dispersal kernel: a review and future directions
The distribution and abundance of plants across the world depends in part on their ability to move, which is commonly characterized by a dispersal kernel. For seeds, the total dispersal kernel (TDK) describes the combined influence of all primary, secondary and higher-order dispersal vectors on the overall dispersal kernel for a plant individual, population, species or community. Understanding the role of each vector within the TDK, and their combined influence on the TDK, is critically important for being able to predict plant responses to a changing biotic or abiotic environment. In addition, fully characterizing the TDK by including all vectors may affect predictions of population spread. Here, we review existing research on the TDK and discuss advances in empirical, conceptual modelling and statistical approaches that will facilitate broader application. The concept is simple, but few examples of well-characterized TDKs exist. We find that significant empirical challenges exist, as many studies do not account for all dispersal vectors (e.g. gravity, higher-order dispersal vectors), inadequately measure or estimate long-distance dispersal resulting from multiple vectors and/or neglect spatial heterogeneity and context dependence. Existing mathematical and conceptual modelling approaches and statistical methods allow fitting individual dispersal kernels and combining them to form a TDK; these will perform best if robust prior information is available. We recommend a modelling cycle to parameterize TDKs, where empirical data inform models, which in turn inform additional data collection. Finally, we recommend that the TDK concept be extended to account for not only where seeds land, but also how that location affects the likelihood of establishing and producing a reproductive adult, i.e. the total effective dispersal kernel
An integarted surgical suite management information system
The operational aspects, application areas, and results achieved from an integrated surgical suite management information system are described. The system, which has been operating within Henry Ford Hospital in Detroit, Michigan, for 4 years, captures comprehensive data for each surgical episode, performs extensive edits on these data to assure data base integrity, and utilizes this data base in multiple applications. These applications include fixed-format reporting for medical staff and management; ad hoc retrieval capabilities to support research, education, and decision making; and linkage to other hospital systems to reduce both data redundancy and paper flow.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/45000/1/10916_2005_Article_BF02222176.pd
Advancing an interdisciplinary framework to study seed dispersal ecology
Although dispersal is generally viewed as a crucial determinant for the fitness of any organism, our understanding of its role in the persistence and spread of plant populations remains incomplete. Generalizing and predicting dispersal processes are challenging due to context dependence of seed dispersal, environmental heterogeneity and interdependent processes occurring over multiple spatial and temporal scales. Current population models often use simple phenomenological descriptions of dispersal processes, limiting their ability to examine the role of population persistence and spread, especially under global change. To move seed dispersal ecology forward, we need to evaluate the impact of any single seed dispersal event within the full spatial and temporal context of a plantâs life history and environmental variability that ultimately influences a populationâs ability to persist and spread. In this perspective, we provide guidance on integrating empirical and theoretical approaches that account for the context dependency of seed dispersal to improve our ability to generalize and predict the consequences of dispersal, and its anthropogenic alteration, across systems. We synthesize suitable theoretical frameworks for this work and discuss concepts, approaches and available data from diverse subdisciplines to help operationalize concepts, highlight recent breakthroughs across research areas and discuss ongoing challenges and open questions. We address knowledge gaps in the movement ecology of seeds and the integration of dispersal and demography that could benefit from such a synthesis. With an interdisciplinary perspective, we will be able to better understand how global change will impact seed dispersal processes, and potential cascading effects on plant population persistence, spread and biodiversity
SARS-CoV-2 seroprevalence in pregnant women in Kilifi, Kenya from March 2020 to March 2022
BackgroundSeroprevalence studies are an alternative approach to estimating the extent of transmission of SARS-CoV-2 and the evolution of the pandemic in different geographical settings. We aimed to determine the SARS-CoV-2 seroprevalence from March 2020 to March 2022 in a rural and urban setting in Kilifi County, Kenya.MethodsWe obtained representative random samples of stored serum from a pregnancy cohort study for the period March 2020 to March 2022 and tested for antibodies against the spike protein using a qualitative SARS-CoV-2 ELISA kit (Wantai, total antibodies). All positive samples were retested for anti-SARS-CoV-2 anti-nucleocapsid antibodies (Euroimmun, ELISA kits, NCP, qualitative, IgG) and anti-spike protein antibodies (Euroimmun, ELISA kits, QuantiVac; quantitative, IgG).ResultsA total of 2,495 (of 4,703 available) samples were tested. There was an overall trend of increasing seropositivity from a low of 0% [95% CI 0â0.06] in March 2020 to a high of 89.4% [95% CI 83.36â93.82] in Feb 2022. Of the Wantai test-positive samples, 59.7% [95% CI 57.06â62.34] tested positive by the Euroimmun anti-SARS-CoV-2 NCP test and 37.4% [95% CI 34.83â40.04] tested positive by the Euroimmun anti-SARS-CoV-2 QuantiVac test. No differences were observed between the urban and rural hospital but villages adjacent to the major highway traversing the study area had a higher seroprevalence.ConclusionAnti-SARS-CoV-2 seroprevalence rose rapidly, with most of the population exposed to SARS-CoV-2 within 23âmonths of the first cases. The high cumulative seroprevalence suggests greater population exposure to SARS-CoV-2 than that reported from surveillance data
International Consensus Statement on Rhinology and Allergy: Rhinosinusitis
Background: The 5 years since the publication of the first International Consensus Statement on Allergy and Rhinology: Rhinosinusitis (ICARâRS) has witnessed foundational progress in our understanding and treatment of rhinologic disease. These advances are reflected within the more than 40 new topics covered within the ICARâRSâ2021 as well as updates to the original 140 topics. This executive summary consolidates the evidenceâbased findings of the document. Methods: ICARâRS presents over 180 topics in the forms of evidenceâbased reviews with recommendations (EBRRs), evidenceâbased reviews, and literature reviews. The highest grade structured recommendations of the EBRR sections are summarized in this executive summary. Results: ICARâRSâ2021 covers 22 topics regarding the medical management of RS, which are grade A/B and are presented in the executive summary. Additionally, 4 topics regarding the surgical management of RS are grade A/B and are presented in the executive summary. Finally, a comprehensive evidenceâbased management algorithm is provided. Conclusion: This ICARâRSâ2021 executive summary provides a compilation of the evidenceâbased recommendations for medical and surgical treatment of the most common forms of RS
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