165 research outputs found
Scaling Behavior Of Atomic Trajectories In Confined Fluids
We study the dependence of D, a quantity that has previously been associated with the fractal dimension of an atomic trajectory, on the scale on which it is measured. Single-particle and relative trajectories are generated by molecular-dynamics simulations of Lennard-Jones atoms permanently trapped in a spherical pore. Transient trapping is studied with a generalized Langevin model of dynamics. Confinement of trajectories allows D to exceed 2; in the case of permanent trapping, D diverges
Computational Study Of Molecular Hydrogen In Zeolite Na-A. II. Density Of Rotational States And Inelastic Neutron Scattering Spectra
Part I of this series [J. Chem. Phys. 111, 7599 (1999)] describes a simulation of H(2) adsorbed within zeolite Na-A in which a block Lanczos procedure is used to generate the first several (9) rotational eigenstates of H(2), modeled as a rigid rotor, and equilibrated at a given temperature via Monte Carlo sampling. Here, we show that rotational states are strongly perturbed by the electrostatic fields in the solid. Wave functions and densities of rotational energy states are presented. Simulated neutron spectra are compared with inelastic neutron scattering data. Comparisons are made with IR spectra in which rotational levels may appear due to rovibrational coupling. (C) 2001 American Institute of Physics
Linking Landscape Characteristics to Local Grizzly Bear Abundance Around Glacier National Park
Grizzly bear (Ursus arctos) habitat use has been extensively studied, but habitat has rarely been linked to demographic parameters and habitat models have not accounted for variation in detection or spatial autocorrelation. We collected bear hair from bear hair traps and rub trees in and around Glacier National Park (GNP) in northwestern Montana and genotyped the samples to identify individuals. We developed a hierarchical model with 1) explicit landscape and habitat variables that we theorized might influence abundance, 2) separate sub-models of detection probability for each sampling type, 3) covariates to explain variation in detection, 4) a conditional autoregressive (CAR) term to account for spatial autocorrelation, and 5) weights to identify most important variables. Road density and percent mesic habitat best explained variation in female grizzly bear abundance and the spatial autocorrelation term was not supported. Female abundance was higher where road density was lower and where more mesic habitat exists. Detection of females increased with rub tree sampling effort. Road density best explained variation in male grizzly bear abundance and the spatial autocorrelation term was supported. More male bears occurred in areas of low road density. Detection of males increased with rub tree and hair trap sampling effort and decreased with time. Our finding that road density influences abundance concurs with conclusions of earlier studies that road density influences habitat use
Computational Study Of Molecular Hydrogen In Zeolite Na-A. I. Potential Energy Surfaces And Thermodynamic Separation Factors For Ortho And Para Hydrogen
We simulate H-2 adsorbed within zeolite Na-A. We use a block Lanczos procedure to generate the first several (9) rotational eigenstates of the molecule, which is modeled as a rigid, quantum rotor with an anisotropic polarizability and quadrupole moment. The rotor interacts with Na cations and O anions; interaction parameters are chosen semiempirically and the truncation of electrostatic fields is handled with a switching function. A Monte Carlo proceedure is used to sample a set of states based on the canonical distribution. Potential energy surfaces, favorable adsorbtion sites, and distributions of barriers to rotation are analyzed. Separation factors for ortho-parahydrogen are calculated; at low temperatures, these are controlled by the ease of rotational tunneling through barriers. (C) 1999 American Institute of Physics
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Costs of hospital care for hypertension in an insured population without an outpatient medicines benefit: an observational study in the Philippines
<p>Abstract</p> <p>Background</p> <p>Hypertension is the number one attributable risk factor for death throughout the world and a major contributor to morbidity, mortality, and increasing health care expenditures in the Philippines. Lack of access to outpatient antihypertensive medicines leads to avoidable disease progression and costly inpatient admissions. We estimated the cost to the Philippine Health Insurance Corporation (PhilHealth), which generally does not cover outpatient medicines, for inpatient care for hypertension and its sequelae.</p> <p>Methods</p> <p>Using PhilHealth inpatient claims for discharges between July 1, 2002 and December 31, 2005, we describe costs to PhilHealth for hospitalizations classified by primary discharge diagnoses into hospitalizations for hypertension; hypertensive heart and/or renal disease; other definite; and other possible consequences of untreated hypertension and assess disease trajectory for patients with more than one admission.</p> <p>Results</p> <p>PhilHealth reimbursed US $56 million for 444,628 hospitalizations for hypertension-related diagnoses incurred by 360,016 patients during 3.5 years; 42% of admissions were for essential or secondary hypertension; 19% for hypertensive heart or renal disease; and 39% for other consequences of untreated hypertension. Among 60,659 patients admitted during the first 18 months of the study with a diagnosis of essential or secondary hypertension, 9% were hospitalized again for treatment of sequelae; older individuals (vs. =< 40 years old), men, dependents (vs. members), and those who were employed (vs. in the private membership category) were more likely to be hospitalized again; as were those whose first admission during the study period was for consequences of hypertension (vs. essential or secondary hypertension).</p> <p>Conclusion</p> <p>Inpatient care for hypertension and its sequelae is expensive. Since many hospitalizations may be avoided with antihypertensive pharmacologic therapy, an outpatient medicines benefit may be one cost-effective policy option for PhilHealth.</p
Phosphorylated neurofilament H (pNF-H) as a potential diagnostic marker for neurological disorders in horses
The current study aimed at the investigating the potential use of phosphorylated neurofilament H (pNF-H) as a diagnostic biomarker for neurologic disorders in the horse. Paired serum and cerebrospinal fluid (CSF) samples (n = 88) and serum only (n = 30) were obtained from horses diagnosed with neurologic disorders and clinically healthy horses as control. The neurologic horses consisted of equine protozoal myeloencephalitis (EPM) (38 cases) and cervical vertebral malformation (CVM) (23 cases). Levels of pNF-H were determined using an ELISA. The correlation between CSF and serum concentrations of pNF-H was evaluated using Spearman's Rank test and the significance of the difference among the groups was assessed using a nonparametric test. Horses had higher pNF-H levels in the CSF than serum. Horses afflicted with EPM had significantly higher serum pNF-H levels in comparison to controls or CVM cases. The correlation between CSF and serum pNF-H levels was poor in both the whole study population and among subgroups of horses included in the study. There was significant association between the likelihood of EPM and the concentrations of pNF-H in either the serum or CSF. These data suggest that pNF-H could be detected in serum and CSF samples from neurologic and control horses. This study demonstrated that pNF-H levels in serum and CSF have the potential to provide objective information to help in the early diagnosis of horses afflicted with neurologic disorders
Need for and Access to Health Care and Medicines: Are There Gender Inequities?
Objective: Differences between women and men in political and economic empowerment, education, and health risks are well-documented. Similar gender inequities in access to care and medicines have been hypothesized but evidence is lacking. Methods: We analyzed 2002 World Health Survey data for 257,922 adult respondents and 80,932 children less than 5 years old from 53 mostly low and middle-income countries. We constructed indicators of need for, access to, and perceptions of care, and we described the number of countries with equal and statistically different proportions of women and men for each indicator. Using multivariate logistic regression models, we estimated effects of gender on our study outcomes, overall and by household poverty. Findings: Women reported significantly more need for care for three of six chronic conditions surveyed, and they were more likely to have at least one of the conditions (OR 1.41 [95% CI 1.38, 1.44]). Among those with reported need for care, there were no consistent differences in access to care between women and men overall (e.g., treatment for all reported chronic conditions, OR 1.00 [0.96, 1.04]) or by household poverty. Of concern, access to care for chronic conditions was distressingly low among both men and women in many countries, as was access to preventive services among boys and girls less than 5 years old. Conclusions: These cross-country results do not suggest a systematic disadvantage of women in access to curative care and medicines for treating selected chronic conditions or acute symptoms, or to preventive services among boys and girls
Diffusion-Limited Reactions In Spherical Cavities
We study a quenching reaction occurring at sinks within a spherical cavity and at the cavity surface. One may think of reactions at these two, distinct locations as two, coupled reactive channels. Reactions of the type D* + A--\u3eD + A are studied in the limit of nondilute A, present at both locations, and dilute D, present within the cavity. We use a Monte Carlo algorithm to compute mean rates, pseudo-first-order rates and branching ratios, and compare with results obtained by assuming that the two reactive channels operate in parallel. The ratio of activities of the two channels are varied; static and moving sinks are studied. We discuss an application to the determination of pore structure by NMR (nuclear magnetic resonance)
Grizzly Bear Population Trend Estimated Using Genetic Detection
We use genetic detection data from natural bear rub sites to estimate annual rate of change for a threatened grizzly bear (Ursus arctos) population in the 33,300 km2 Northern Continental Divide Ecosystem (NCDE) in northwestern Montana, USA). Bear rubs were surveyed twice annually in 2004, 2009-2012 (3,580 – 4,805 rubs). We detected approximately 1/3 of the grizzly bear population annually. Using spatially explicit capturerecapture (SCR) models in a maximum likelihood framework, we estimate growth rate from the slope of a linear regression fit to the log of density estimates. To evaluate the usefulness of our estimates, we compare them to estimates of ? made using independent data from known-fate telemetry monitoring for our population. Total annual population rate of change was 1.056 (95% CI = 1.033-1.079). The large sample sizes generated by genetic detection provided information on variation in density and trend within the NCDE useful for designing monitoring and management strategies tailored to area-specific needs and priorities. Local rates of change within the NCDE were higher in areas of lower density and population expansion than in Glacier NP, the area with highest density. As density increased, the amount of space used by bears estimated by the SCR models, ?, decreased. Hair collection from natural bear rub sites was an efficient sampling approach able to generate precise estimates of annual growth rate from 2 years of data
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