6,812 research outputs found

    Early environmental field research career exploration: An analysis of impacts on precollege apprentices

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    Research apprenticeships offer opportunities for deep understanding of scientific practice, transparency about research careers, and possible transformational effects on precollege youth. We examined two consecutive field-based environmental biology apprenticeship programs designed to deliver realistic career exploration and connections to research scientists. The Shaw Institute for Field Training (SIFT) program combines introductory field-skills training with research assistance opportunities, and the subsequent Tyson Environmental Research Fellowships (TERF) program provides immersive internships on university field station–based research teams. In a longitudinal mixed-methods study grounded in social cognitive career theory, changes in youth perspectives were measured during program progression from 10th grade through college, evaluating the efficacy of encouraging career path entry. Results indicate SIFT provided self-knowledge and career perspectives more aligned with reality. During SIFT, differences were found between SIFT-only participants compared with those who progressed to TERF. Transition from educational activities to fieldwork with scientists was a pivotal moment at which data showed decreased or increased interest and confidence. Continuation to TERF provided deeper relationships with role models who gave essential early-career support. Our study indicates the two-stage apprenticeship structure influenced persistence in pursuit of an environmental research career pathway. Recommendations for other precollege environmental career–exploration programs are presented

    Dynamical symmetry of isobaric analog 0+ states in medium mass nuclei

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    An algebraic sp(4) shell model is introduced to achieve a deeper understanding and interpretation of the properties of pairing-governed 0+ states in medium mass atomic nuclei. The theory, which embodies the simplicity of a dynamical symmetry approach to nuclear structure, is shown to reproduce the excitation spectra and fine structure effects driven by proton-neutron interactions and isovector pairing correlations across a broad range of nuclei.Comment: 7 pages, 5 figure

    New effective interaction for pfpf-shell nuclei and its implications for the stability of the NN=ZZ=28 closed core

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    The effective interaction GXPF1 for shell-model calculations in the full pfpf shell is tested in detail from various viewpoints such as binding energies, electro-magnetic moments and transitions, and excitation spectra. The semi-magic structure is successfully described for NN or Z=28 nuclei, 53^{53}Mn, 54^{54}Fe, 55^{55}Co and 56,57,58,59^{56,57,58,59}Ni, suggesting the existence of significant core-excitations in low-lying non-yrast states as well as in high-spin yrast states. The results of N=ZN=Z odd-odd nuclei, 54^{54}Co and 58^{58}Cu, also confirm the reliability of GXPF1 interaction in the isospin dependent properties. Studies of shape coexistence suggest an advantage of Monte Carlo Shell Model over conventional calculations in cases where full-space calculations still remain too large to be practical.Comment: 29pages, 26figures, to be published in Physical Review

    The Need for Large-Scale, Longitudinal Empirical Studies in Middle Level Education Research

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    This essay describes and discusses the ongoing need for large-scale, longitudinal, empirical research studies focused on middle grades education. After a statement of the problem and concerns, the essay describes several prior middle grades efforts and research studies. Recommendations for future research efforts to inform policy decisions are provided, including roles for the Middle Level Education Research Special Interest Group (MLER SIG) of the American Educational Research Association (AERA) and other national organizations

    Preparedness for use of the rapid result HIV self-test by gay men and other men who have sex with men (MSM): a mixed methods exploratory study among MSM and those involved in HIV prevention and care

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    Objectives: The aim of the study was to explore preparedness for the HIV self-test among men who have sex with men (MSM) and those involved in HIV prevention and care. Methods: A mixed methods exploratory research design was employed, detailing awareness and willingness to use the self-test and the perceived barriers and facilitators to implementation. Quantitative and qualitative data collection and analysis were completed in parallel. Descriptive and inferential analysis of cross-sectional bar-based survey data collected from MSM through a self-completed questionnaire and oral fluid specimen collection (n = 999) was combined with qualitative, thematic, analysis of data collected through 12 expert focus groups (n = 55) consisting of gay men, National Health Service (NHS) staff, community organizations, entrepreneurs and activists. Findings were subsequently combined and assessed for synergies. Results: Among MSM, self-test awareness was moderate (55%). Greater awareness was associated with increased educational attainment [adjusted odds ratio 1.51; 95% confidence interval (CI) 1.00–2.30; P = 0.05] and previous history of sexually transmitted infection (STI) testing (adjusted odds ratio 1.63; 95% CI 1.11–2.39; P = 0.01). Willingness to use the test was high (89%) and associated with meeting sexual partners online (unadjusted odds ratio 1.96; 95% CI 1.31–2.94; P < 0.001). Experts highlighted the overall acceptability of self-testing; it was understood as convenient, discreet, accessible, and with a low burden to services. However, some ambivalence towards self-testing was reported; it could reduce opportunities to engage with wider services, wider health issues and the determinants of risk. Conclusions: Self-testing represents an opportunity to reduce barriers to HIV testing and enhance prevention and access to care. Levels of awareness are moderate but willingness to use is high. Self-testing may amplify health inequalities

    Minority Stress and Leukocyte Gene Expression In Sexual Minority Men Living With Treated HIV Infection

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    Sexual minority (i.e., non-heterosexual) individuals experience poorer mental and physical health, accounted for in part by the additional burden of sexual minority stress occurring from being situated in a culture favoring heteronormativity. Informed by previous research, the purpose of this study was to identify the relationship between sexual minority stress and leukocyte gene expression related to inflammation, cancer, immune function, and cardiovascular function. Sexual minority men living with HIV who were on anti-retroviral medication, had viral load \u3c 200 copies/mL, and had biologically confirmed, recent methamphetamine use completed minority stress measures and submitted blood samples for RNA sequencing on leukocytes. Differential gene expression and pathway analyses were conducted comparing those with clinically elevated minority stress (n = 18) and those who did not meet the clinical cutoff (n = 20), covarying reactive urine toxicology results for very recent stimulant use. In total, 90 differentially expressed genes and 138 gene set pathways evidencing 2-directional perturbation were observed at false discovery rate (FDR) \u3c 0.10. Of these, 41 of the differentially expressed genes and 35 of the 2-directionally perturbed pathways were identified as functionally related to hypothesized mechanisms of inflammation, cancer, immune function, and cardiovascular function. The neuroactive-ligand receptor pathway (implicated in cancer development) was identified using signaling pathway impact analysis. Our results suggest several potential biological pathways for future work investigating the relationship between sexual minority stress and health

    Nuclear symmetry energy and the r-mode instability of neutron stars

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    We analyze the role of the symmetry energy slope parameter LL on the {\it r}-mode instability of neutron stars. Our study is performed using both microscopic and phenomenological approaches of the nuclear equation of state. The microscopic ones include the Brueckner--Hartree--Fock approximation, the well known variational equation of state of Akmal, Pandharipande and Ravenhall, and a parametrization of recent Auxiliary Field Diffusion Monte Carlo calculations. For the phenomenological approaches, we use several Skyrme forces and relativisic mean field models. Our results show that the {\it r}-mode instability region is smaller for those models which give larger values of LL. The reason is that both bulk (ξ\xi) and shear (η\eta) viscosities increase with LL and, therefore, the damping of the mode is more efficient for the models with larger LL. We show also that the dependence of both viscosities on LL can be described at each density by simple power-laws of the type ξ=AξLBξ\xi=A_{\xi}L^{B_\xi} and η=AηLBη\eta=A_{\eta}L^{B_\eta}. Using the measured spin frequency and the estimated core temperature of the pulsar in the low-mass X-ray binary 4U 1608-52, we conclude that observational data seem to favor values of LL larger than ∼50\sim 50 MeV if this object is assumed to be outside the instability region, its radius is in the range 11.5−1211.5-12(11.5−1311.5-13) km, and its mass 1.4M⊙1.4M_\odot(2M⊙2M_\odot). Outside this range it is not possible to draw any conclusion on LL from this pulsar.Comment: 10 pages, 6 figures. Version published in Physical Review

    Pairing and alpha-like quartet condensation in N=Z nuclei

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    We discuss the treatment of isovector pairing by an alpha-like quartet condensate which conserves exactly the particle number, the spin and the isospin. The results show that the quartet condensate describes accurately the isovector pairing correlations in the ground state of systems with an equal number of protons and neutronsComment: 4 pages, to appear in Journal of Physics: Conference Serie

    Contribution of the massive photon decay channel to neutrino cooling of neutron stars

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    We consider massive photon decay reactions via intermediate states of electron-electron-holes and proton-proton-holes into neutrino-antineutrino pairs in the course of neutron star cooling. These reactions may become operative in hot neutron stars in the region of proton pairing where the photon due to the Higgs-Meissner effect acquires an effective mass mγm_{\gamma} that is small compared to the corresponding plasma frequency. The contribution of these reactions to neutrino emissivity is calculated; it varies with the temperature and the photon mass as T3/2mγ7/2e−mγ/TT^{3/2}m_{\gamma}^{7/2} e^{-m_{\gamma}/T} for T<mγT < m_{\gamma}. Estimates show that these processes appear as extra efficient cooling channels of neutron stars at temperatures T≃(109−1010)T \simeq (10^9-10^{10}) K.Comment: accepted to publication in Zh. Eksp. Teor. Fiz. (JETP

    Local Density Approximation for proton-neutron pairing correlations. I. Formalism

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    In the present study we generalize the self-consistent Hartree-Fock-Bogoliubov (HFB) theory formulated in the coordinate space to the case which incorporates an arbitrary mixing between protons and neutrons in the particle-hole (p-h) and particle-particle (p-p or pairing) channels. We define the HFB density matrices, discuss their spin-isospin structure, and construct the most general energy density functional that is quadratic in local densities. The consequences of the local gauge invariance are discussed and the particular case of the Skyrme energy density functional is studied. By varying the total energy with respect to the density matrices the self-consistent one-body HFB Hamiltonian is obtained and the structure of the resulting mean fields is shown. The consequences of the time-reversal symmetry, charge invariance, and proton-neutron symmetry are summarized. The complete list of expressions required to calculate total energy is presented.Comment: 22 RevTeX page
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