222 research outputs found

    Dynamics of optomechanical spatial solitons in dual-nanoweb structures

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    We theoretically investigate the stability and dynamics of self-channelled beams that form via nonlocal optomechanical interactions in dual-nanoweb microstructured fibers. These "optomechanicons" represent a novel class of spatial soliton

    Degradative Tubular Lysosomes Link Pexophagy To Starvation And Early Aging In C. Elegans

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    Organelle-specific autophagy directs degradation of eukaryotic organelles under certain conditions. Like other organelles, peroxisomes are subject to autophagic turnover at lysosomes. However, peroxisome autophagy (pexophagy) has yet to be analyzed in a live-animal system, limiting knowledge on its regulation during an animal\u27s life. Here, we generated a tandem-fluorophore reporter that enabled real-time tracking of pexophagy in live Caenorhabditis elegans. We observed that pexophagy occurred at a population of non-canonical, tubular lysosomes specifically during starvation and aging. Remarkably, in these contexts, tubular lysosomes were the predominant type of lysosome in the intestine, transforming from vesicles. Though we found that peroxisomes were largely eliminated in early adulthood, they appeared restored in new generations. We identified peroxisomal genes that regulated age-dependent peroxisome loss and demonstrated that modifying this process altered animal lifespan. These findings reveal new facets of peroxisome homeostasis relevant to aging and challenge the prevailing perception of lysosome homogeneity in autophagy

    Resolving the mystery of milliwatt-threshold opto-mechanical self-oscillation in dual-nanoweb fiber

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    It is interesting to pose the question: How best to design an optomechanical device, with no electronics, optical cavity, or laser gain, that will self-oscillate when pumped in a single pass with only a few mW of single-frequency laser power? One might begin with a mechanically resonant and highly compliant system offering very high optomechanical gain. Such a system, when pumped by single-frequency light, might self-oscillate at its resonant frequency. It is well-known, however, that this will occur only if the group velocity dispersion of the light is high enough so that phonons causing pump-to-Stokes conversion are sufficiently dissimilar to those causing pump-to-anti-Stokes conversion. Recently it was reported that two light-guiding membranes 20 μm wide, ∼500 nm thick and spaced by ∼500 nm, suspended inside a glass fiber capillary, oscillated spontaneously at its mechanical resonant frequency (∼6 MHz) when pumped with only a few mW of single-frequency light. This was surprising, since perfect Raman gain suppression would be expected. In detailed measurements, using an interferometric side-probing technique capable of resolving nanoweb movements as small as 10 pm, we map out the vibrations along the fiber and show that stimulated intermodal scattering to a higher-order optical mode frustrates gain suppression, permitting the structure to self-oscillate. A detailed theoretical analysis confirms this picture. This novel mechanism makes possible the design of single-pass optomechanical oscillators that require only a few mW of optical power, no electronics nor any optical resonator. The design could also be implemented in silicon or any other suitable material

    Are Mandates the Answer? Improving Palliative Care and Pain Management in Vermont

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    Background: The Vermont legislature (bill H.435, Sec. 19) has tasked the Vermont Board of Medical Practice (VBMP) with making a formal recommendation on improving Vermont health professionals’ knowledge and practice of Palliative Care and Pain Management (PC/PM). In collaboration with the VBMP, our group set out to answer the following questions: • How confident/competent are VT physicians in the practice of PC/PM? • What are the barriers to achieving optimal patient care in PC/PM? • Do VT physicians believe mandatory CME would improve the overall quality of care in PC/PM? • What are the best methods of providing Continuing Medical Education (CME)?https://scholarworks.uvm.edu/comphp_gallery/1040/thumbnail.jp

    Scaling Properties of the Giant Dipole Resonance Width in Hot Rotating nuclei

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    We study the systematics of the giant dipole resonance width Γ\Gamma in hot rotating nuclei as a function of temperature TT, spin JJ and mass AA. We compare available experimental results with theoretical calculations that include thermal shape fluctuations in nuclei ranging from A=45 to A=208. Using the appropriate scaled variables, we find a simple phenomenological function Γ(A,T,J)\Gamma(A,T,J) which approximates the global behavior of the giant dipole resonance width in the liquid drop model. We reanalyze recent experimental and theoretical results for the resonance width in Sn isotopes and 208^{208}Pb.Comment: LaTeX, 4 pages with 4 figures (to appear in Phys. Rev. Lett.

    Compilation of Giant Electric Dipole Resonances Built on Excited States

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    Giant Electric Dipole Resonance (GDR) parameters for gamma decay to excited states with finite spin and temperature are compiled. Over 100 original works have been reviewed and from some 70 of which more than 300 parameter sets of hot GDR parameters for different isotopes, excitation energies, and spin regions have been extracted. All parameter sets have been brought onto a common footing by calculating the equivalent Lorentzian parameters. The current compilation is complementary to an earlier compilation by Samuel S. Dietrich and Barry L. Berman (At. Data Nucl. Data Tables 38(1988)199-338) on ground-state photo-neutron and photo-absorption cross sections and their Lorentzian parameters. A comparison of the two may help shed light on the evolution of GDR parameters with temperature and spin. The present compilation is current as of January 2006.Comment: 31 pages including 1 tabl

    Quasi-fission reactions as a probe of nuclear viscosity

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    Fission fragment mass and angular distributions were measured from the ^{64}Ni+^{197}Au reaction at 418 MeV and 383 MeV incident energy. A detailed data analysis was performed, using the one-body dissipation theory implemented in the code HICOL. The effect of the window and the wall friction on the experimental observables was investigated. Friction stronger than one-body was also considered. The mass and angular distributions were consistent with one-body dissipation. An evaporation code DIFHEAT coupled to HICOL was developed in order to predict reaction time scales required to describe available data on pre-scission neutron multiplicities. The multiplicity data were again consistent with one-body dissipation. The cross-sections for touch, capture and quasi-fission were also obtained.Comment: 25 pages REVTeX, 3 tables, 13 figures, submitted to Phys. Rev

    Does rapid urbanization aggravate health disparities? Reflections on the epidemiological transition in Pune, India

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    Background: Rapid urbanization in low- and middle-income countries reinforces risk and epidemiological transition in urban societies, which are characterized by high socioeconomic gradients. Limited availability of disaggregated morbidity data in these settings impedes research on epidemiological profiles of different population subgroups. Objective: The study aimed to analyze the epidemiological transition in the emerging megacity of Pune with respect to changing morbidity and mortality patterns, also taking into consideration health disparities among different socioeconomic groups. Design: A mixed-methods approach was used, comprising secondary analysis of mortality data, a survey among 900 households in six neighborhoods with different socioeconomic profiles, 46 in-depth interviews with laypeople, and expert interviews with 37 health care providers and 22 other health care workers. Results: The mortality data account for an epidemiological transition with an increasing number of deaths due to non-communicable diseases (NCDs) in Pune. The share of deaths due to infectious and parasitic diseases remained nearly constant, though the cause of deaths changed considerably within this group. The survey data and expert interviews indicated a slightly higher prevalence of diabetes and hypertension among higher socioeconomic groups, but a higher incidence and more frequent complications and comorbidities in lower socioeconomic groups. Although the self-reported morbidity for malaria, gastroenteritis, and tuberculosis did not show a socioeconomic pattern, experts estimated the prevalence in lower socioeconomic groups to be higher, though all groups in Pune would be affected. Conclusions: The rising burden of NCDs among all socioeconomic groups and the concurrent persistence of communicable diseases pose a major challenge for public health. Improvement of urban health requires a stronger focus on health promotion and disease prevention for all socioeconomic groups with a holistic understanding of urban health. In order to derive evidence-based solutions and interventions, routine surveillance data become indispensable

    Attitudes About COVID-19 and Health (ATTACH): Online Survey and Mixed Methods Study

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    Background: Behavioral mitigation strategies to slow the spread of COVID-19 have resulted in sweeping lifestyle changes, with short- and long-term psychological, well-being, and quality of life implications. The Attitudes About COVID-19 and Health (ATTACH) study focuses on understanding attitudes and beliefs while considering the impact on mental and physical health and the influence of broader demographic and geographic factors on attitudes, beliefs, and mental health burden. / Objective: In this assessment of our first wave of data collection, we provide baseline cohort description of the ATTACH study participants in the United Kingdom, the United States, and Mexico. Additionally, we assess responses to daily poll questions related to COVID-19 and conduct a cross-sectional analysis of baseline assessments collected in the UK between June 26 and October 31, 2020. / Methods: The ATTACH study uses smartphone app technology and online survey data collection. Participants completed poll questions related to COVID-19 2 times daily and a monthly survey assessing mental health, social isolation, physical health, and quality of life. Poll question responses were graphed using 95% Clopper–Pearson (exact) tests with 95% CIs. Pearson correlations, hierarchical linear regression analyses, and generalized linear models assessed relationships, predictors of self-reported outcomes, and group differences, respectively. / Results: By October 31, 2020, 1405, 80, and 90 participants had consented to participate in the UK, United States, and Mexico, respectively. Descriptive data for the UK daily poll questions indicated that participants generally followed social distancing measures, but worry and negative impacts on families increased as the pandemic progressed. Although participants generally reported feeling that the reasons for current measures had been made clear, there was low trust that the government was doing everything in its power to meet public needs. In the UK, 1282 participants also completed a monthly survey (94.99% [1326/1396] White, 72.22% [1014/1404] female, and 20.12% [277/1377] key or essential workers); 18.88% (242/1282) of UK participants reported a preexisting mental health disorder, 31.36% (402/1282) reported a preexisting chronic medical illness, and 35.11% (493/1404) were aged over 65; 57.72% (740/1282) of participants reported being more sedentary since the pandemic began, and 41.89% (537/1282) reported reduced access to medical care. Those with poorer mental health outcomes lived in more deprived neighborhoods, in larger households (Ps<.05), had more preexisting mental health disorders and medical conditions, and were younger than 65 years (all Ps<.001). / Conclusions: Communities who have been exposed to additional harm during the COVID-19 pandemic were experiencing worse mental outcomes. Factors including having a medical condition, or living in a deprived neighborhood or larger household were associated with heightened risk. Future longitudinal studies should investigate the link between COVID-19 exposure, mental health, and sociodemographic and residential characteristics

    Fission Hindrance in hot 216Th: Evaporation Residue Measurements

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    The fusion evaporation-residue cross section for 32S+184W has been measured at beam energies of E_beam = 165, 174, 185, 196, 205, 215, 225, 236, 246,and 257 MeV using the ATLAS Fragment Mass Analyzer. The data are compared with Statistical Model calculations and it is found that a nuclear dissipation strength, which increases with excitation energy, is required to reproduce the excitation function. A comparison with previously published data show that the dissipation strength depends strongly on the shell structure of the nuclear system.Comment: 15 pages 9 figure
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