28,132 research outputs found
A Time-Series Analysis of U.S. Kidney Transplantation and the Waiting List: Donor Substitution Effects and "Dirty Altruism"
This paper provides an econometric analysis of the relationship between live and deceased (cadaveric) kidney donations for the United States for the period 1992:IV through 2006:II. Statistical analysis shows that increases in deceased donor transplants reduce future live donor grafts, controlling for both waiting list effects and exogenous trends. This result has important, and potentially dire, implications for efforts to reduce the organ shortage by increasing use of cadaver donors.Kidney Transplantations; Donor Substitution Effects; Dirty Altruism; Cointegration
New Method to Calculate Electrical Forces Acting on a Sphere in an Electrorheological Fluid
We describe a method to calculate the electrical force acting on a sphere in
a suspension of dielectric spheres in a host with a different dielectric
constant, under the assumption that a spatially uniform electric field is
applied. The method uses a spectral representation for the total electrostatic
energy of the composite. The force is expressed as a certain gradient of this
energy, which can be expressed in a closed analytic form rather than evaluated
as a numerical derivative. The method is applicable even when both the spheres
and the host have frequency-dependent dielectric functions and nonzero
conductivities, provided the system is in the quasistatic regime. In principle,
it includes all multipolar contributions to the force, and it can be used to
calculate multi-body as well as pairwise forces. We also present several
numerical examples, including host fluids with finite conductivities. The force
between spheres approaches the dipole-dipole limit, as expected, at large
separations, but departs drastically from that limit when the spheres are
nearly in contact. The force may also change sign as a function of frequency
when the host is a slightly conducting fluid.Comment: 29 pages, 8 figures, Accepted for Publication in Physical Review
Non-Gaussianity in Axion N-flation Models
We study perturbations in the multifield axion N-flation model, taking account of the full cosine potential. We find significant differences from previous analyses which made a quadratic approximation to the potential. The tensor-to-scalar ratio and the scalar spectral index move to lower values, which nevertheless provide an acceptable fit to observation. Most significantly, we find that the bispectrum non-Gaussianity parameter fNL may be large, typically of order 10 for moderate values of the axion decay constant, increasing to of order 100 for decay constants slightly smaller than the Planck scale. Such a non-Gaussian fraction is detectable. We argue that this property is generic in multifield models of hilltop inflation
Prolongation of greater occipital neural blockade with 10% lidocaine neurolysis: a case series of a new technique
INTRODUCTION: Greater occipital nerve blocks (GONB) have been used for headache but their benefit may be short. Ready et al performed intrathecal injections on rabbits and reported neurologic/histologic changes that required concentrations of at least 8%. Our study tests the hypothesis that the neurolytic effects of GONB with 10% lidocaine can prolong relief.
METHODS: After an approval from Henry Ford Hospital Institutional Review Board, a chart review was performed for patients who had GONB with 10% lidocaine. Patients received 10% lidocaine after short response (/ \u3e50% relief) to GONB with 1 cc of a solution containing 9 mL 0.5 % bupivacaine and 40 mg methylprednisolone. They received a block with 10% lidocaine with volume given at
RESULTS: Thirteen patients were reviewed; 12 were female and the mean age was 47. Ten were diagnosed with migraine, and three with occipital neuralgia; 12 had bilateral symptoms. Baseline VAS prior to 10% lidocaine averaged 86.92 mm. The mean volume injected per nerve was 1.096 mL. There was significant decrease in mean% VAS with 10% lidocaine at 60.4% (mean: -52.69 mm) (
CONCLUSION: Ten percent lidocaine may be a useful neurolytic agent in prolonging the duration of GONB
Workshop on evaluating personal search
The first ECIR workshop on Evaluating Personal Search was
held on 18th April 2011 in Dublin, Ireland. The workshop
consisted of 6 oral paper presentations and several discussion sessions. This report presents an overview of the scope and contents of the workshop and outlines the major outcomes
Volumetric three-dimensional intravascular ultrasound visualization using shape-based nonlinear interpolation
BACKGROUND: Intravascular ultrasound (IVUS) is a standard imaging modality for identification of plaque formation in the coronary and peripheral arteries. Volumetric three-dimensional (3D) IVUS visualization provides a powerful tool to overcome the limited comprehensive information of 2D IVUS in terms of complex spatial distribution of arterial morphology and acoustic backscatter information. Conventional 3D IVUS techniques provide sub-optimal visualization of arterial morphology or lack acoustic information concerning arterial structure due in part to low quality of image data and the use of pixel-based IVUS image reconstruction algorithms. In the present study, we describe a novel volumetric 3D IVUS reconstruction algorithm to utilize IVUS signal data and a shape-based nonlinear interpolation. METHODS: We developed an algorithm to convert a series of IVUS signal data into a fully volumetric 3D visualization. Intermediary slices between original 2D IVUS slices were generated utilizing the natural cubic spline interpolation to consider the nonlinearity of both vascular structure geometry and acoustic backscatter in the arterial wall. We evaluated differences in image quality between the conventional pixel-based interpolation and the shape-based nonlinear interpolation methods using both virtual vascular phantom data and in vivo IVUS data of a porcine femoral artery. Volumetric 3D IVUS images of the arterial segment reconstructed using the two interpolation methods were compared. RESULTS: In vitro validation and in vivo comparative studies with the conventional pixel-based interpolation method demonstrated more robustness of the shape-based nonlinear interpolation algorithm in determining intermediary 2D IVUS slices. Our shape-based nonlinear interpolation demonstrated improved volumetric 3D visualization of the in vivo arterial structure and more realistic acoustic backscatter distribution compared to the conventional pixel-based interpolation method. CONCLUSIONS: This novel 3D IVUS visualization strategy has the potential to improve ultrasound imaging of vascular structure information, particularly atheroma determination. Improved volumetric 3D visualization with accurate acoustic backscatter information can help with ultrasound molecular imaging of atheroma component distribution
Student Success: A Literature Review of Faculty to Student Mentoring
This review summarizes the literature on university faculty to student mentoring programs. There has been a proliferation of mentoring programs because of the perceived benefit to student persistence and retention. While mentoring programs have become common, the research on these programs has not kept pace. Shortcomings identified thirty years ago such as lack of theoretical guidance, lack of operational definition of mentoring, and poor design continue to plague mentoring research. Recommendations to address these shortcomings and improve internal and external validity are examined. As universities continue to have increasingly constrained resources, and pressure to demonstrate strategies to help students be successful, evidence-based research will be increasingly desired. If shortcomings in mentoring research can be addressed, mentoring programs hold the potential to be part of a university’s strategic plan to help students be successful
Delivering Preventive Health Care Information to More versus Less Health-Oriented Consumers: A Comparative Demographic Analysis
Preventive health care (PHC) is the awareness and efforts a person undertakes to enhance and preserve physical, mental, and emotional health for today and future. Although PHC information is widely available, people are not utilizing the information to improve their health. We examine PHC information sources utilized by persons who are more health-oriented vs. less health-oriented. The less health-oriented individuals were identified as: low educational attainment, low income, men, younger age, unmarried, and non-White. A factor analysis produced three primary sources of PHC information sources: print, institutional, and electronic and audio-visual delivery systems. An ANOVA compared how more health-oriented individuals differed from less health-oriented individuals regarding the importance of PHC information sources.
As expected, men and unmarried individuals placed less importance on PHC sources information. Younger individuals placed greater importance on institutional and electronic sources of PHC information. Furthermore, non-Whites considered institutional sources of PHC to be more important than Whites, and those without college degrees considered print sources to be more important than those with college degree. There were no differences among income groups
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