5,829 research outputs found

    Time Variations in Elemental Abundances in Solar Energetic Particle Events

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    The Solar Isotope Spectrometer (SIS) on-board the Advanced Composition Explorer has a large collection power and high telemetry rate, making it possible to study elemental abundances in large solar energetic particle (SEP) events as a function of time. Results have now been obtained for more than 25 such events. Understanding the causes of these variations is key to obtaining reliable solar elemental abundances and to understanding solar acceleration processes. Such variations have been previously attributed to two models: (1) a mixture of an initial impulsive phase having enhanced heavy element abundances with a longer gradual phase with coronal abundances and (2) rigidity dependent escape from CME-driven shocks through plasma waves generated by wave-particle interactions. In this second model the injected abundances are assumed to be coronal. Both these models can be expected to depend upon solar longitude since impulsive events are associated with flares at longitudes well-connected magnetically to the observer, and shock properties and connection of the observer to the shock are also longitude dependent. We present results on temporal variations from event to event and within events and show that they appear to have a longitude dependence. We show that the events which have been well-explained by model (2) tend to be near central meridian or the west limb. In addition, we show that there are events with little time variation and heavy element enhancements similar to those of impulsive events. These events seem to be better explained by model (1) with only an impulsive phase

    The impact of the demographic transition on dengue in Thailand: Insights from a statistical analysis and mathematical modeling

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    Background: An increase in the average age of dengue hemorrhagic fever (DHF) cases has been reported in Thailand. The cause of this increase is not known. Possible explanations include a reduction in transmission due to declining mosquito populations, declining contact between human and mosquito, and changes in reporting. We propose that a demographic shift toward lower birth and death rates has reduced dengue transmission and lengthened the interval between large epidemics. Methods and Findings: Using data from each of the 72 provinces of Thailand, we looked for associations between force of infection (a measure of hazard, defined as the rate per capita at which susceptible individuals become infected) and demographic and climactic variables. We estimated the force of infection from the age distribution of cases from 1985 to 2005. We find that the force of infection has declined by 2% each year since a peak in the late 1970s and early 1980s. Contrary to recent findings suggesting that the incidence of DHF has increased in Thailand, we find a small but statistically significant decline in DHF incidence since 1985 in a majority of provinces. The strongest predictor of the change in force of infection and the mean force of infection is the median age of the population. Using mathematical simulations of dengue transmission we show that a reduced birth rate and a shift in the population's age structure can explain the shift in the age distribution of cases, reduction of the force of infection, and increase in the periodicity of multiannual oscillations of DHF incidence in the absence of other changes. Conclusions: Lower birth and death rates decrease the flow of susceptible individuals into the population and increase the longevity of immune individuals. The increase in the proportion of the population that is immune increases the likelihood that an infectious mosquito will feed on an immune individual, reducing the force of infection. Though the force of infection has decreased by half, we find that the critical vaccination fraction has not changed significantly, declining from an average of 85% to 80%. Clinical guidelines should consider the impact of continued increases in the age of dengue cases in Thailand. Countries in the region lagging behind Thailand in the demographic transition may experience the same increase as their population ages. The impact of demographic changes on the force of infection has been hypothesized for other diseases, but, to our knowledge, this is the first observation of this phenomenon

    Modelling colloids with Baxter's adhesive hard sphere model

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    The structure of the Baxter adhesive hard sphere fluid is examined using computer simulation. The radial distribution function (which exhibits unusual discontinuities due to the particle adhesion) and static structure factor are calculated with high accuracy over a range of conditions and compared with the predictions of Percus--Yevick theory. We comment on rigidity in percolating clusters and discuss the role of the model in the context of experiments on colloidal systems with short-range attractive forces.Comment: 14 pages, 7 figures. (For proceedings of "Structural arrest in colloidal systems with short-range attractive forces", Messina, December 2003

    The Pivotal Role of the Pharmacist in a Primary Care Office

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    Abstract The profession of pharmacy has evolved from a dispensing role to an interdisciplinary clinical role in patient care. One area of patient care expertise is Medication Therapy Management (MTM), which includes services such as pharmacotherapy, medication therapy reviews, disease management, immunizations and other clinical services. In various studies, pharmacists conducting MTM have shown improved patient outcomes in community pharmacy and hospital settings. Amidst the valuable services all healthcare professionals are providing, increasing medical costs and consequences have become overwhelming, leading to negative patient outcomes. A lack of primary care physicians (PCPs) may contribute to these distressing facts. Gaps in communication between hospital, PCPs and community pharmacies also contribute to negative patient outcomes. Pharmacists can bridge the gap in miscommunication and help improve patient outcomes. Thus far in practice, pharmacists have had a limited role in primary care settings. The objective of this study is to determine if the addition of pharmacists providing clinical services (i.e. MTM) in a primary care setting can support the prescribers’ patient care demands. For this observational, exploratory research, the primary care settings under study will be all Federally Qualified Health Centers (FQHCs) in Ohio. IRB approval will be acquired before contact is made with participants. The contact person from each FQHC has been identified from the HRSA Office of Pharmacy Affairs. A script will be used to gather email addresses for the manager, physician, nurse and pharmacist, if available, from the contact person. A Qualtrics survey will be administered to these participants via email. The purpose of this study is to establish components of patient care in a primary care office, specifically FQHCs, that other medical professionals identify as lacking, which pharmacists can provide. A consent form, information about the study and a link to the survey will be provided in an email. The survey will include demographic, open-ended and 5-point Likert-type scale (1=strongly agree, 5=strongly disagree) questions. Reliability and validity of the survey will be established by a thorough search of the literature and expert review. Submitted answers will be analyzed with the appropriate statistical tests

    On stability of discretizations of the Helmholtz equation (extended version)

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    We review the stability properties of several discretizations of the Helmholtz equation at large wavenumbers. For a model problem in a polygon, a complete kk-explicit stability (including kk-explicit stability of the continuous problem) and convergence theory for high order finite element methods is developed. In particular, quasi-optimality is shown for a fixed number of degrees of freedom per wavelength if the mesh size hh and the approximation order pp are selected such that kh/pkh/p is sufficiently small and p=O(logk)p = O(\log k), and, additionally, appropriate mesh refinement is used near the vertices. We also review the stability properties of two classes of numerical schemes that use piecewise solutions of the homogeneous Helmholtz equation, namely, Least Squares methods and Discontinuous Galerkin (DG) methods. The latter includes the Ultra Weak Variational Formulation

    Validation of monoclonal antibody F99/97.6.1 for immunohistochemical staining of brain and tonsil in mule deer (\u3ci\u3eOdocoileus hemionus\u3c/i\u3e) with chronic wasting disease

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    A new monoclonal antibody (MAb), F99/97.6.1, that has been used to demonstrate scrapieassociated prion protein PrPSc in brain and lymphoid tissues of domestic sheep with scrapie was used in an immunohistochemistry assay for diagnosis of chronic wasting disease (CWD) in mule deer (Odocoileus hemionus). The MAb F99/97.6.1 immunohistochemistry assay was evaluated in brain and tonsil tissue from 100 mule deer that had spongiform encephalopathy compatible with CWD and from 1,050 mule deer outside the CWD-endemic area. This MAb demonstrated abnormal protease-resistant prion protein (PrPres) in brains of all of the 100 mule deer and in 99 of the 100 tonsil samples. No immunostaining was seen in samples collected from deer outside the endemic area. MAb F99/97.6.1 demonstrated excellent properties for detection of PrPres in fresh, frozen, or mildly to moderately autolytic samples of brain and tonsil. This immunohistochemistry assay is a sensitive, specific, readily standardized diagnostic test for CWD in deer

    Validation of monoclonal antibody F99/97.6.1 for immunohistochemical staining of brain and tonsil in mule deer (\u3ci\u3eOdocoileus hemionus\u3c/i\u3e) with chronic wasting disease

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    A new monoclonal antibody (MAb), F99/97.6.1, that has been used to demonstrate scrapieassociated prion protein PrPSc in brain and lymphoid tissues of domestic sheep with scrapie was used in an immunohistochemistry assay for diagnosis of chronic wasting disease (CWD) in mule deer (Odocoileus hemionus). The MAb F99/97.6.1 immunohistochemistry assay was evaluated in brain and tonsil tissue from 100 mule deer that had spongiform encephalopathy compatible with CWD and from 1,050 mule deer outside the CWD-endemic area. This MAb demonstrated abnormal protease-resistant prion protein (PrPres) in brains of all of the 100 mule deer and in 99 of the 100 tonsil samples. No immunostaining was seen in samples collected from deer outside the endemic area. MAb F99/97.6.1 demonstrated excellent properties for detection of PrPres in fresh, frozen, or mildly to moderately autolytic samples of brain and tonsil. This immunohistochemistry assay is a sensitive, specific, readily standardized diagnostic test for CWD in deer

    Towards a developmental state? Provincial economic policy in South Africa

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    This paper explores the meaning of the developmental state for spatial economic policy in South Africa. Two main questions are addressed: do provincial governments have a role to play in promoting economic prosperity, and to what extent do current provincial policies possess the attributes of a developmental state? These attributes are defined as the ability to plan longer term, to focus key partners on a common agenda, and to mobilise state resources to build productive capabilities. The paper argues that the developmental state must harness the power of government at every level to ensure that each part of the country develops to its potential. However, current provincial capacity is uneven, and weakest where support is needed most. Many provinces seem to have partial strategies and lack the wherewithal for sustained implementation. Coordination across government appears to be poor. The paper concludes by suggesting ways provincial policies could be strengthened

    Galactic Cosmic Rays from Supernova Remnants: II Shock Acceleration of Gas and Dust

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    This is the second paper (the first was astro-ph/9704267) of a series analysing the Galactic Cosmic Ray (GCR) composition and origin. In this we present a quantitative model of GCR origin and acceleration based on the acceleration of a mixture of interstellar and/or circumstellar gas and dust by supernova remnant blast waves. We present results from a nonlinear shock model which includes (i) the direct acceleration of interstellar gas-phase ions, (ii) a simplified model for the direct acceleration of weakly charged dust grains to energies of order 100keV/amu simultaneously with the gas ions, (iii) frictional energy losses of the grains colliding with the gas, (iv) sputtering of ions of refractory elements from the accelerated grains and (v) the further shock acceleration of the sputtered ions to cosmic ray energies. The calculated GCR composition and spectra are in good agreement with observations.Comment: to appear in ApJ, 51 pages, LaTeX with AAS macros, 9 postscript figures, also available from ftp://wonka.physics.ncsu.edu/pub/elliso
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