1,195 research outputs found

    Curing the Dutch Disease: Lessons for United States Disability Policy

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    In the 1990s, the United States reformed welfare programs targeted on single mothers and dramatically reduced their benefit receipt while increasing their employment and economic wellbeing. Despite increasing calls to do the same for working age people with disabilities in the U.S., disability cash transfer program rolls continue to grow as their employment rates fall and their economic well-being stagnates. In contrast to the failure to reform United States disability policy, the Netherlands, once considered to have the most out of control disability program among OECD nations, initiated reforms in 2002 that have dramatically reduced their disability cash transfer rolls, while maintaining a strong but less generous social minimum safety net for all those who do not work. Here we review disability program growth in the United States and the Netherlands, link it to changes in their disability policies and show that while difficult to achieve, fundamental disability reform is possible. We argue that shifts in SSI policies that focus on better integrating working age men and women with disabilities into the work force along the lines of those implemented for single mothers in the 1990s, together with SSDI program changes that better integrate private and public disability insurance programs along the lines of the reforms in the Netherlands, offer the best hope of improving their employment rates and economic well-being as well as reducing SSDI/SSI program growth.

    Steklov problem on differential forms

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    In this paper we study spectral properties of Dirichlet-to-Neumann map on differential forms obtained by a slight modification of the definition due to Belishev and Sharafutdinov. The resulting operator Λ\Lambda is shown to be self-adjoint on the subspace of coclosed forms and to have purely discrete spectrum there.We investigate properies of eigenvalues of Λ\Lambda and prove a Hersch-Payne-Schiffer type inequality relating products of those eigenvalues to eigenvalues of Hodge Laplacian on the boundary. Moreover, non-trivial eigenvalues of Λ\Lambda are always at least as large as eigenvalues of Dirichlet-to-Neumann map defined by Raulot and Savo. Finally, we remark that a particular case of pp-forms on the boundary of 2p+22p+2-dimensional manifold shares a lot of important properties with the classical Steklov eigenvalue problem on surfaces.Comment: 18 page

    Rapid reduction of sigma(1)-Receptor binding and F-18-FDG uptake in rat gliomas after in vivo treatment with doxorubicin

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    sigma-Receptors are strongly overexpressed in most rodent and human tumors and are proliferation markers. To evaluate the potential of a radiolabeled sigma(1)-ligand for therapy monitoring, we compared early changes of C-11-1-(3,4-dimethoxyphenethyl)-4-(3-phenylpropyl)piperazine (C-11-SA4503) binding and F-18-FDG uptake in gliomas after in vivo chemotherapy. Methods: C6 cells (2.5 x 10(6)) were subcutaneously injected into the right shoulder of male Wistar rats. After 7 cl, the tumor volume was 0.60 +/- 0.08 cm(3). Animals then received either saline or doxorubicin (8 mg/kg, intraperitoneally). One control and 1 treated rat were imaged simultaneously, 24 or 48 h after treatment, under pentobarbital anesthesia. Rodents (n = 20) were scanned first with C-11-SA4503 (25 MBq, intravenously) followed more than 100 min afterward by 18F-FDG (20 MBq, intravenously), using a dedicated small-animal PET camera (60-min protocol, tumors in the field of view). Tumor homogenates were prepared and subjected to sigma-receptor assays. The biodistribution of 18F-FDG was assessed. Results: Tumors appeared 4-5 d after inoculation and grew exponentially. No significant reduction of tumor growth was visible within 48 h after doxorubicin treatment. Both PET tracers visualized the tumors and showed reduced uptake after chemotherapy (C-11-SA4503: 26.5% +/- 6.5% at 24 h, 26.5% +/- 7.5% at 48 h; 18F-FDG: 22.6% +/- 3.2% at 24 h, 27.4% +/- 3.2% at 48 h; ex vivo F-18-FDG: 22.4% +/- 5.4% at 24 h, 31.7% +/- 12.7% at 48 h). sigma(1)-Receptor density in treated tumors was also reduced (from 172 +/- 35 to 125 +/- 28 fmol/mg of protein). Conclusion: Both C-11-SA4503 binding and 18F-FDG uptake declined in gliomas after chemotherapy. Decreased binding of C-11-SA4503 corresponded to a loss of (sigma(1)-receptors from the tumors. Changes in tracer uptake preceded the morphologic changes by at least 48 h

    Powerful Water Masers in Active Galactic Nuclei

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    Luminous water maser emission in the 6_(16)-5_(23) line at 22 GHz has been detected from two dozen galaxies. In all cases the emission is confined to the nucleus and has been found only in AGN, in particular, in Type 2 Seyferts and LINERs. I argue that most of the observed megamaser sources are powered by X-ray irradiation of dense gas by the central engine. After briefly reviewing the physics of these X-Ray Dissociation Regions, I discuss in detail the observations of the maser disk in NGC 4258, its implications, and compare alternative models for the maser emission. I then discuss the observations of the other sources that have been imaged with VLBI to date, and how they do or do not fit into the framework of a thin, rotating disk, as in NGC 4258. Finally, I briefly discuss future prospects, especially the possibility of detecting other water maser transitions.Comment: 45 pages, 16 figures. Refereed and greatly expanded version of my review talk at the ASA meeting in Lorne, July 2001. To appear in Proceedings of the Astronomical Society of Australi

    Curing the Dutch Disease: Lessons for United States Disability Policy

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    In the 1990s, the United States reformed welfare programs targeted on single mothers and dramatically reduced their benefit receipt while increasing their employment and economic wellbeing. Despite increasing calls to do the same for working age people with disabilities in the U.S., disability cash transfer program rolls continue to grow as their employment rates fall and their economic well-being stagnates. In contrast to the failure to reform United States disability policy, the Netherlands, once considered to have the most out of control disability program among OECD nations, initiated reforms in 2002 that have dramatically reduced their disability cash transfer rolls, while maintaining a strong but less generous social minimum safety net for all those who do not work. Here we review disability program growth in the United States and the Netherlands, link it to changes in their disability policies and show that while difficult to achieve, fundamental disability reform is possible. We argue that shifts in SSI policies that focus on better integrating working age men and women with disabilities into the work force along the lines of those implemented for single mothers in the 1990s, together with SSDI program changes that better integrate private and public disability insurance programs along the lines of the reforms in the Netherlands, offer the best hope of improving their employment rates and economic well-being as well as reducing SSDI/SSI program growth.Social Security Administrationhttp://deepblue.lib.umich.edu/bitstream/2027.42/61813/1/wp188.pd

    Automated Galaxy Morphology: A Fourier Approach

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    We use automated surface photometry and pattern classification techniques to morphologically classify galaxies. The two-dimensional light distribution of a galaxy is reconstructed using Fourier series fits to azimuthal profiles computed in concentric elliptical annuli centered on the galaxy. Both the phase and amplitude of each Fourier component have been studied as a function of radial bin number for a large collection of galaxy images using principal component analysis. We find that up to 90 percent of the variance in many of these Fourier profiles may be characterized in as few as 3 principal components and their use substantially reduces the dimensionality of the classification problem. We use supervised learning methods in the form of artificial neural networks to train galaxy classifiers that detect morphological bars at the 85-90 percent confidence level and can identify the Hubble type with a 1-sigma scatter of 1.5 steps on the 16-step stage axis of the revised Hubble system. Finally, we systematically characterize the adverse effects of decreasing resolution and S/N on the quality of morphological information predicted by these classifiers.Comment: Accepted to Astrophysical Journal, 43 pages, 12 figure

    The Ultraluminous X-ray Source NGC 1313 X-2 (MS 0317.7-6647) and its Environment

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    We present new optical and {\it Chandra} observations of the field containing the ultraluminous X-ray source NGC 1313 X-2. On an ESO 3.6 m image, the {\it Chandra} error box embraces a R=21.6R=21.6 point-like object and excludes a previously proposed optical counterpart. The resulting X-ray/optical flux ratio of NGC 1313 X-2 is ∌500\sim 500. The value of fX/foptf_X/f_{opt}, the X-ray variability history and the spectral distribution derived from a re-analysis of the {\it ROSAT}, {\it ASCA} and {\it XMM} data indicate a luminous X-ray binary in NGC 1313 as a likely explanation for NGC 1313 X-2. If the X-ray soft component observed in the {\it XMM} EPIC spectrum originates from an accretion disk, the inferred mass of the compact remnant is ≈100M⊙\approx 100 M_\odot, making it an intermediate mass black hole. The derived optical luminosity (L≈105L⊙L\approx 10^5 L_\odot) is consistent with that of a ≈15−20M⊙\approx 15-20 M_\odot companion. The properties of the environment of NGC 1313 X-2 are briefly discussed.Comment: 12 pages, 6 figures; submitted to The Astrophysical Journa

    Assessing cognition and daily function in early dementia using the cognitive-functional composite:findings from the Catch-Cog study cohort

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    BackgroundThe cognitive-functional composite (CFC) was designed to improve the measurement of clinically relevant changes in predementia and early dementia stages. We have previously demonstrated its good test-retest reliability and feasibility of use. The current study aimed to evaluate several quality aspects of the CFC, including construct validity, clinical relevance, and suitability for the target population.MethodsBaseline data of the Capturing Changes in Cognition study was used: an international, prospective cohort study including participants with subjective cognitive decline (SCD), mild cognitive impairment (MCI), Alzheimer's disease (AD) dementia, and dementia with Lewy bodies (DLB). The CFC comprises seven existing cognitive tests focusing on memory and executive functions (EF) and the informant-based Amsterdam Instrumental Activities of Daily Living Questionnaire (A-IADL-Q). Construct validity and clinical relevance were assessed by (1) confirmatory factor analyses (CFA) using all CFC subtests and (2) linear regression analyses relating the CFC score (independent) to reference measures of disease severity (dependent), correcting for age, sex, and education. To assess the suitability for the target population, we compared score distributions of the CFC to those of traditional tests (Alzheimer's Disease Assessment Scale-Cognitive subscale, Alzheimer's Disease Cooperative Study-Activities of Daily Living scale, and Clinical Dementia Rating scale).ResultsA total of 184 participants were included (age 71.88.4; 42% female; n=14 SCD, n=80 MCI, n=78AD, and n=12 DLB). CFA showed that the hypothesized three-factor model (memory, EF, and IADL) had adequate fit (CFI=.931, RMSEA=.091, SRMR=.06). Moreover, worse CFC performance was associated with more cognitive decline as reported by the informant (=.61, p</p

    Radiation Dosimetry of a Novel Adenosine A(2A) Receptor Radioligand [C-11]Preladenant Based on PET/CT Imaging and Ex Vivo Biodistribution in Rats

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    [C-11]Preladenant was developed as a novel adenosine A(2A) receptor PET radioligand. The aim of this study was to determine the radiation dosimetry of [C-11]preladenant and to investigate whether dosimetry estimation based on organ harvesting can be replaced by positron emission tomography (PET)/x-ray computed tomography (CT) imaging in rats. Male Wistar rats (n = 35) were i.v. injected with [C-11]preladenant. The tracer biodistribution was determined by organ harvesting at 1, 5, 15, 30, 60, and 90 min post injection. Hollow organs including the stomach, intestines, and urinary bladder were harvested with contents. In 10 rats, a 90-min dynamic PET/CT scan of the torso was acquired. Twenty volumes of interest (VOIs) were manually drawn on the PET image using the CT image of the same animal as anatomical reference. The dynamic time-activity curves were used to calculate organ residence times (RTs). Human radiation dosimetry estimates, derived from rat data, were calculated with OLINDA/EXM 1.1. PET-imaging and organ-harvesting estimated comparable organ RTs, with differences of 6-27 %, except for the lungs, pancreas, and urinary bladder, with differences of 48, 53, and 60, respectively. The critical organ was the small intestine with a dose of 25 mu Sv/MBq. The effective doses (EDs) calculated from imaging-based and organ-harvesting-derived data were 5.5 and 5.6 mu Sv/MBq, respectively, using the International Commission on Radiological Protection 60 tissue weighting factors. The ED of [C-11]preladenant (2 mSv for a 370-MBq injected dose) is comparable with other C-11-labeled PET tracers. Estimation of the radiation dosimetry of [C-11]preladenant by PET/CT imaging in rats is feasible and gives comparable results to organ harvesting, provided that small VOIs are used and the content of hollow organs is taken into account. Dosimetry by PET imaging can strongly reduce the number of laboratory animals required
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