622 research outputs found

    Far-ultraviolet signatures of the 3He(n,tp) reaction in noble gas mixtures

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    Previous work showed that the 3He(n,tp) reaction in a cell of 3He at atmospheric pressure generated tens of far-ultraviolet photons per reacted neutron. Here we report amplification of that signal by factors of 1000 and more when noble gases are added to the cell. Calibrated filter-detector measurements show that this large signal is due to noble-gas excimer emissions, and that the nuclear reaction energy is converted to far-ultraviolet radiation with efficiencies of up to 30%. The results have been placed on an absolute scale through calibrations at the NIST SURF III synchrotron. They suggest possibilities for high-efficiency neutron detectors as an alternative to existing proportional counters

    Solar wind observations with the ion composition instrument aboard the ISEE-3 ICE spacecraft

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    The principal observations obtained by the Ion Composition Instrument (ICI) flown on the ISEE-3/ICE spacecraft, which was in the solar wind from September 1978 to the end of 1982, before being directed to the far magnetotail of the Earth are discussed. Almost continuous observations were made of the abundances of 3He++, 4He++, O6+, O7+, Ne, Si and Fe in various charge states, and of their bulk speeds and temperatures. The results show that there is a strong tendency in the collisionless solar wind for the ionic temperatures to be proportional to the masses. For heavier ions these temperatures exceed typical coronal electron temperatures. 4He++, especially in high speed streams, moves faster than H+, and travels at the same speed as heavier ions. The mechanism leading to this heating and rapid streaming is still not entirely clear

    Plasma IMS Composition Measurements for Europa and Ganymede

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    NASA and ESA are planning the joint Europa Jupiter System Mission (EJSM) to the Jupiter system with specific emphasis to Europa and Ganymede, respectively. The Japanese Space Agency is also planning an orbiter mission to explore Jupiter's magnetosphere and the Galilean satellites. For NASA's Jupiter Europa Orbiter (JEO) we are developing the 3D Ion Mass Spectrometer (IMS) with two main goals which can also be applied to the other Galilean moons, 1) measure the plasma interaction between Europa and Jupiter's magnetosphere and 2) infer the 4n surface composition to trace elemental [1] and significant isotopic levels. The first goal supports the magnetometer (MAG) measurements, primarily directed at detection of Europa's sub-surface ocean, while the second gives information about transfer of material between the Galilean moons, and between the moon surfaces and subsurface layers putatively including oceans. The measurement of the interactions for all the Galilean moons can be used to trace the in situ ion measurements of pickup ions back to either Europa's or Ganymede's surface from the respectively orbiting spacecraft. The IMS instrument, being developed under NASA's Astrobiology Instrument Development Program, would maximally achieve plasma measurement requirements for JEO and EJSM while moving forward our knowledge of Jupiter system composition and source processes to far higher levels than previously envisaged

    Fisk-Gloeckler Suprathermal Proton Spectrum in the Heliosheath and the Local Interstellar Medium

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    Convergence of suprathermal keV-MeV proton and ion spectra approximately to the Fisk-Gloeckler (F-G) form j(E) = j(sub 0) E(sup -1.5) in Voyager land 2 heliosheath measurements is suggestive of distributed acceleration in Kolmogorov turbulence which may extend well beyond the heliopause into the local interstellar medium (LISM). Turbulence of this type is already indicated by interstellar radio scintillation measurements of electron density power spectra. Previously published extrapolations (Cooper et al., 2003, 2006) of the LISM proton spectrum from eV to GeV energies are highly consistent with the F-G power-law and further indicative of such turbulence and LISM effectiveness of the F-G cascade acceleration process. The LISM pressure computed from this spectrum well exceeds that from current estimates for the LISM magnetic field, so exchange of energy between the protons and the magnetic field would likely have a strong role in evolution of the turbulence as per the F-G theory and as long ago proposed for cosmic ray energies by Parker and others. Pressure-dependent estimates of the LISM field strength should not ignore this potentially strong and even dominant contribution from the plasma. Presence of high-beta suprathermal plasma on LISM field lines could significantly affect interactions with the heliospheric outer boundary region and might potentially account for distributed and more discrete features in ongoing measurements of energetic neutral emission from the Interstellar Boundary Explorer (IBEX) mission

    Early life stress and macaque annygdala hypertrophy: preliminary evidence for a role for the serotonin transporter gene

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    Background: Children exposed to early life stress (ELS) exhibit enlarged amygdala volume in comparison to controls. the primary goal of this study was to examine amygdala volumes in bonnet macaques subjected to maternal variable foraging demand (VFD) rearing, a well-established model of ELS. Preliminary analyses examined the interaction of ELS and the serotonin transporter gene on amygdala volume. Secondary analyses were conducted to examine the association between amygdala volume and other stress-related variables previously found to distinguish VFD and non-VFD reared animals.Methods: Twelve VFD-reared and nine normally reared monkeys completed MRI scans on a 3T system (mean age = 5.2 years).Results: Left amygdala volume was larger in VFD vs. control macaques. Larger amygdala volume was associated with: high cerebrospinal fluid concentrations of corticotropin releasing-factor (CRF) determined when the animals were in adolescence (mean age = 2.7 years); reduced fractional anisotropy (FA) of the anterior limb of the internal capsule (ALIC) during young adulthood (mean age = 5.2 years) and timid anxiety-like responses to an intruder during full adulthood (mean age = 8.4 years). Right amygdala volume varied inversely with left hippocampal neurogenesis assessed in late adulthood (mean age = 8.7 years). Exploratory analyses also showed a gene-by-environment effect, with VFD-reared macaques with a single short allele of the serotonin transporter gene exhibiting larger amygdala volume compared to VFD-reared subjects with only the long allele and normally reared controls.Conclusion: These data suggest that the left amygdala exhibits hypertrophy after ELS, particularly in association with the serotonin transporter gene, and that amygdala volume variation occurs in concert with other key stress-related behavioral and neurobiological parameters observed across the lifecycle. Future research is required to understand the mechanisms underlying these diverse and persistent changes associated with ELS and amygdala volume.National Institute for Mental HealthNIMHNARSAD Mid-investigator AwardSuny Downstate Med Ctr, Dept Psychiat & Behav Sci, Brooklyn, NY 11203 USAUniversidade Federal de São Paulo, Dept Psiquiatria, São Paulo, BrazilMt Sinai Sch Med, Dept Psychiat, New York, NY USAMt Sinai Sch Med, Dept Neurosci, New York, NY USAMt Sinai Sch Med, Dept Radiol, New York, NY USANew York State Psychiat Inst & Hosp, New York, NY 10032 USAMichael E Debakey VA Med Ctr, Mental Hlth Care Line, Houston, TX USABaylor Coll Med, Menninger Dept Psychiat & Behav Sci, Houston, TX 77030 USAYale Univ, Sch Med, Dept Psychiat, New Haven, CT USANatl Ctr PTSD, Clin Neurosci Div, West Haven, CT USANew York State Psychiat Inst & Hosp, Dept Mol Imaging & Neuropathol, New York, NY 10032 USAColumbia Univ, Coll Phys & Surg, Dept Psychiat, New York, NY USAColumbia Univ, Coll Phys & Surg, Dept Pathol & Cell Biol, New York, NY USAComprehensive NeuroSci Corp, Westchester, NY USAUniv Miami Hlth Sytems, Dept Psychiat & Behav Sci, Miami, FL USAEmory Univ, Sch Med, Dept Psychiat & Behav Sci, Emory, GA USAUniversidade Federal de São Paulo, Dept Psiquiatria, São Paulo, BrazilNational Institute for Mental Health: R01MH65519-01National Institute for Mental Health: R01MH098073NIMH: R21MH066748NIMH: R01MH59990AWeb of Scienc

    Compton scattering beyond the impulse approximation

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    We treat the non-relativistic Compton scattering process in which an incoming photon scatters from an N-electron many-body state to yield an outgoing photon and a recoil electron, without invoking the commonly used frameworks of either the impulse approximation (IA) or the independent particle model (IPM). An expression for the associated triple differential scattering cross section is obtained in terms of Dyson orbitals, which give the overlap amplitudes between the N-electron initial state and the (N-1) electron singly ionized quantum states of the target. We show how in the high energy transfer regime, one can recover from our general formalism the standard IA based formula for the cross section which involves the ground state electron momentum density (EMD) of the initial state. Our formalism will permit the analysis and interpretation of electronic transitions in correlated electron systems via inelastic x-ray scattering (IXS) spectroscopy beyond the constraints of the IA and the IPM.Comment: 7 pages, 1 figur

    Cross-reactivity of anti-HIV-1 T cell immune responses among the major HIV-1 clades in HIV-1-positive individuals from 4 continents

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    Background. the genetic diversity of human immunodeficiency virus type 1 (HIV-1) raises the question of whether vaccines that include a component to elicit antiviral T cell immunity based on a single viral genetic clade could provide cellular immune protection against divergent HIV-1 clades. Therefore, we quantified the cross-clade reactivity, among unvaccinated individuals, of anti-HIV-1 T cell responses to the infecting HIV-1 clade relative to other major circulating clades.Methods. Cellular immune responses to HIV-1 clades A, B, and C were compared by standardized interferon-gamma enzyme-linked immunospot assays among 250 unvaccinated individuals, infected with diverse HIV-1 clades, from Brazil, Malawi, South Africa, Thailand, and the United States. Cross-clade reactivity was evaluated by use of the ratio of responses to heterologous versus homologous ( infecting) clades of HIV-1.Results. Cellular immune responses were predominantly focused on viral Gag and Nef proteins. Cross-clade reactivity of cellular immune responses to HIV-1 clade A, B, and C proteins was substantial for Nef proteins ( ratio, 0.97 [95% confidence interval, 0.89-1.05]) and lower for Gag proteins ( ratio, 0.67 [ 95% confidence interval, 0.62-0.73]). the difference in cross-clade reactivity to Nef and Gag proteins was significant (P < .0001).Conclusions. Cross-clade reactivity of cellular immune responses can be substantial but varies by viral protein.Merck Res Labs, W Point, PA USAMahidol Univ, Bangkok 10700, ThailandMalawi Coll Med, Blantyre, MalawiMinist Populat & Hlth, Lilongwe, MalawiUniv Fed Rio de Janeiro, Rio de Janeiro, BrazilUniversidade Federal de São Paulo, São Paulo, BrazilUniv Witwatersrand, Johannesburg, South AfricaUniversidade Federal de São Paulo, São Paulo, BrazilWeb of Scienc

    Healing Multiculturalism: Middle-Ground Liberal Forgiveness in a Diverse Public Realm

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    This article examines debates about political forgiveness in liberal, pluralist societies. Although the concept of forgiveness is not usually taken up by liberals, I outline a plausible conception by exploring two recent approaches. The first, ‘unattached articulation’, concept requires no real emotional change on the forgiver’s part, but rather a form of civic restraint. In contrast, the second version highlights a strong form of empathy for perpetrators. In spite of their advantages, each concept proves too extreme. The problems are revealed by focusing on the case of the Harkis, who fought for the French during the Algerian war. Often still marginalised in French society, their case helps to highlight the conceivability of a ‘middle-ground’ or moderate concept of political forgiveness. Its core rests on the forgiver’s care for the social world. While this concept brings considerable challenges also, and is not inevitable in any particular case, it entails a more plausible combination of emotional and rational shifts in the forgiver’s world-view. Although the article does not recommend forgiveness by any person or group, it observes, recalling Arendt’s idea of amor mundi or ‘love of the world’, that political forgiveness may sustain a viable connection between diverse citizens’ public and non-public lives

    Mulat-estetiek: ’n Analise van Adam Small se dramas

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    Opsomming In hierdie artikel word die dramakonvensies van Adam Small ondersoek met besondere aandag aan perspektiewe op die mulat as ’n sosiale gegewe. Hierdie element bied ’n gepaste invalshoek omdat dit enersyds ‘n verskynsel is wat Small in sy dramas en ander skryfwerk aansny en daar andersyds ’n uitgebreide literatuur bestaan waarin oor die dramatiese, lewensbeskoulike en literêr-teoretiese inkleding daarvan besin word. Die werk van onder andere Langston Hughes en Derek Walcott word ondersoek om ’n leesstrategie te ontwikkel waarmee die Small-teks geanaliseer kan word.Web of Scienc

    Correlations between Hippocampal Neurogenesis and Metabolic Indices in Adult Nonhuman Primates

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    Increased neurogenesis in feeding centers of the murine hypothalamus is associated with weight loss in diet-induced obese rodents (Kokoeva et al., 2005 and Matrisciano et al., 2010), but this relationship has not been examined in other species. Postmortem hippocampal neurogenesis rates and premortem metabolic parameters were statistically analyzed in 8 chow-fed colony-reared adult bonnet macaques. Dentate gyrus neurogenesis, reflected by the immature neuronal marker, doublecortin (DCX), and expression of the antiapoptotic gene factor, B-cell lymphoma 2 (BCL-2), but not the precursor proliferation mitotic marker, Ki67, was inversely correlated with body weight and crown-rump length. DCX and BCL-2 each correlated positively with blood glucose level and lipid ratio (total cholesterol/high-density lipoprotein). This study demonstrates that markers of dentate gyrus neuroplasticity correlate with metabolic parameters in primates
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