57 research outputs found
Sequential Decay Distortion of Goldhaber Model Widths for Spectator Fragments
Momentum widths of the primary fragments and observed final fragments have
been investigated within the framework of an Antisymmetrized Molecular Dynamics
transport model code (AMD-V) with a sequential decay afterburner (GEMINI). It
is found that the secondary evaporation effects cause the values of a reduced
momentum width, , derived from momentum widths of the final fragments
to be significantly less than those appropriate to the primary fragment but
close to those observed in many experiments. Therefore, a new interpretation
for experiemental momentum widths of projectile-like fragments is presented.Comment: 4 pages, 3 figs. Accepted for publication in Phys. Rev. C as a Rapid
Communicatio
Sequential Decay Distortion of Goldhaber Model Widths for Spectator Fragments
Momentum widths of the primary fragments and observed final fragments have
been investigated within the framework of an Antisymmetrized Molecular Dynamics
transport model code (AMD-V) with a sequential decay afterburner (GEMINI). It
is found that the secondary evaporation effects cause the values of a reduced
momentum width, , derived from momentum widths of the final fragments
to be significantly less than those appropriate to the primary fragment but
close to those observed in many experiments. Therefore, a new interpretation
for experiemental momentum widths of projectile-like fragments is presented.Comment: 4 pages, 3 figs. Accepted for publication in Phys. Rev. C as a Rapid
Communicatio
Neuroimmune activation and increased brain aging in chronic pain patients after the COVID-19 pandemic onset
The COVID-19 pandemic has exerted a global impact on both physical and mental health, and clinical populations have been disproportionally affected. To date, however, the mechanisms underlying the deleterious effects of the pandemic on pre-existing clinical conditions remain unclear. Here we investigated whether the onset of the pandemic was associated with an increase in brain/blood levels of inflammatory markers and MRI-estimated brain age in patients with chronic low back pain (cLBP), irrespective of their infection history. A retrospective cohort study was conducted on 56 adult participants with cLBP (28 âPre-Pandemicâ, 28 âPandemicâ) using integrated Positron Emission Tomography/ Magnetic Resonance Imaging (PET/MRI) and the radioligand [11C]PBR28, which binds to the neuroinflammatory marker 18âŻkDa Translocator Protein (TSPO). Image data were collected between November 2017 and January 2020 (âPre-Pandemicâ cLBP) or between August 2020 and May 2022 (âPandemicâ cLBP). Compared to the Pre-Pandemic group, the Pandemic patients demonstrated widespread and statistically significant elevations in brain TSPO levels (PâŻ=.05, cluster corrected). PET signal elevations in the Pandemic group were also observed when 1) excluding 3 Pandemic subjects with a known history of COVID infection, or 2) using secondary outcome measures (volume of distribution -VT- and VT ratio - DVR) in a smaller subset of participants. Pandemic subjects also exhibited elevated serum levels of inflammatory markers (IL-16; PâŻ<.05) and estimated BA (PâŻ<.0001), which were positively correlated with [11C]PBR28 SUVR (râsâŻâ„âŻ0.35; PâsâŻ<âŻ0.05). The pain interference scores, which were elevated in the Pandemic group (PâŻ<.05), were negatively correlated with [11C]PBR28 SUVR in the amygdala (râŻ=âŻâ0.46; P<.05).
This work suggests that the pandemic outbreak may have been accompanied by neuroinflammation and increased brain age in cLBP patients, as measured by multimodal imaging and serum testing. This study underscores the broad impact of the pandemic on human health, which extends beyond the morbidity solely mediated by the virus itself
Abelian Hidden Sectors at a GeV
We discuss mechanisms for naturally generating GeV-scale hidden sectors in
the context of weak-scale supersymmetry. Such low mass scales can arise when
hidden sectors are more weakly coupled to supersymmetry breaking than the
visible sector, as happens when supersymmetry breaking is communicated to the
visible sector by gauge interactions under which the hidden sector is
uncharged, or if the hidden sector is sequestered from gravity-mediated
supersymmetry breaking. We study these mechanisms in detail in the context of
gauge and gaugino mediation, and present specific models of Abelian GeV-scale
hidden sectors. In particular, we discuss kinetic mixing of a U(1)_x gauge
force with hypercharge, singlets or bi-fundamentals which couple to both
sectors, and additional loop effects. Finally, we investigate the possible
relevance of such sectors for dark matter phenomenology, as well as for low-
and high-energy collider searches.Comment: 43 pages, no figures; v2: to match JHEP versio
Far-Ultraviolet and Far-Infrared Bivariate Luminosity Function of Galaxies: Complex Relation between Stellar and Dust Emission
Far-ultraviolet (FUV) and far-infrared (FIR) luminosity functions (LFs) of
galaxies show a strong evolution from to , but the FIR LF
evolves much stronger than the FUV one. The FUV is dominantly radiated from
newly formed short-lived OB stars, while the FIR is emitted by dust grains
heated by the FUV radiation field. It is known that dust is always associated
with star formation activity. Thus, both FUV and FIR are tightly related to the
star formation in galaxies, but in a very complicated manner. In order to
disentangle the relation between FUV and FIR emissions, we estimate the UV-IR
bivariate LF (BLF) of galaxies with {\sl GALEX} and {\sl AKARI} All-Sky Survey
datasets. Recently we invented a new mathematical method to construct the BLF
with given marginals and prescribed correlation coefficient. This method makes
use of a tool from mathematical statistics, so called "copula". The copula
enables us to construct a bivariate distribution function from given marginal
distributions with prescribed correlation and/or dependence structure. With
this new formulation and FUV and FIR univariate LFs, we analyze various FUV and
FIR data with {\sl GALEX}, {\sl Spitzer}, and {\sl AKARI} to estimate the UV-IR
BLF. The obtained BLFs naturally explain the nonlinear complicated relation
between FUV and FIR emission from star-forming galaxies. Though the faint-end
of the BLF was not well constrained for high- samples, the estimated linear
correlation coefficient was found to be very high, and is remarkably
stable with redshifts (from 0.95 at to 0.85 at ). This implies
the evolution of the UV-IR BLF is mainly due to the different evolution of the
univariate LFs, and may not be controlled by the dependence structure.Comment: 10 pages, 7 figures, Earth, Planets and Space, in pres
The pandemic brain: Neuroinflammation in non-infected individuals during the COVID-19 pandemic
While COVID-19 research has seen an explosion in the literature, the impact of pandemic-related societal and lifestyle disruptions on brain health among the uninfected remains underexplored. However, a global increase in the prevalence of fatigue, brain fog, depression and other âsickness behaviorâ-like symptoms implicates a possible dysregulation in neuroimmune mechanisms even among those never infected by the virus.
We compared fifty-seven âPre-Pandemicâ and fifteen âPandemicâ datasets from individuals originally enrolled as control subjects for various completed, or ongoing, research studies available in our records, with a confirmed negative test for SARS-CoV-2 antibodies. We used a combination of multimodal molecular brain imaging (simultaneous positron emission tomography / magnetic resonance spectroscopy), behavioral measurements, imaging transcriptomics and serum testing to uncover links between pandemic-related stressors and neuroinflammation.
Healthy individuals examined after the enforcement of 2020 lockdown/stay-at-home measures demonstrated elevated brain levels of two independent neuroinflammatory markers (the 18 kDa translocator protein, TSPO, and myoinositol) compared to pre-lockdown subjects. The serum levels of two inflammatory markers (interleukin-16 and monocyte chemoattractant protein-1) were also elevated, although these effects did not reach statistical significance after correcting for multiple comparisons. Subjects endorsing higher symptom burden showed higher TSPO signal in the hippocampus (mood alteration, mental fatigue), intraparietal sulcus and precuneus (physical fatigue), compared to those reporting little/no symptoms. Post-lockdown TSPO signal changes were spatially aligned with the constitutive expression of several genes involved in immune/neuroimmune functions.
This work implicates neuroimmune activation as a possible mechanism underlying the non-virally-mediated symptoms experienced by many during the COVID-19 pandemic. Future studies will be needed to corroborate and further interpret these preliminary findings
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Multi-lingual and multi-cultural information literacy; perspectives, models and good practice
Purpose
This paper reviews current approaches to, and good practice, in information literacy development in multi-lingual and multi-cultural settings, with particular emphasis on provision for international students.
Design/methodology/approach
A selective and critical review of published literature is extended by evaluation of examples of multi-lingual information literacy tutorials and MOOCs.
Findings
Multi-lingual and multi-cultural information literacy are umbrella terms covering a variety of situations and issues. This provision is of increasing importance in an increasingly mobile and multi-cultural world. This article evaluates current approaches and good practice, focusing on issues of culture vis a vis language, the balance between individual and group needs, specific and generic information literacy instruction, and models for information literacy, pedagogy and culture. Recommendations for good practice and for further research are given,
Originality/value
This is one of very few articles critically reviewing how information literacy development is affected by linguistic and cultural factors
Candidates for Inelastic Dark Matter
Although we have yet to determine whether the DAMA data represents a true
discovery of new physics, among such interpretations inelastic dark matter
(IDM) can match the energy spectrum of DAMA very well while not contradicting
the results of other direct detection searches. In this paper we investigate
the general properties that a viable IDM candidate must have and search for
simple models that realize these properties in natural ways. We begin by
determining the regions of IDM parameter space that are allowed by direct
detection searches including DAMA, paying special attention to larger IDM
masses. We observe that an inelastic dark matter candidate with electroweak
interactions can naturally satisfy observational constraints while
simultaneously yielding the correct thermal relic abundance. We comment on
several other proposed dark matter explanations for the DAMA signal and
demonstrate that one of the proposed alternatives -- elastic scattering of dark
matter off electrons -- is strongly disfavored when the modulated and
unmodulated DAMA spectral data are taken into account. We then outline the
general essential features of IDM models in which inelastic scattering off
nuclei is mediated by the exchange of a massive gauge boson, and construct
natural models in the context of a warped extra dimension and supersymmetry.Comment: 44 pages, 6 figures, added reference
The hybrid inflation waterfall and the primordial curvature perturbation
Without demanding a specific form for the inflaton potential, we obtain an
estimate of the contribution to the curvature perturbation generated during the
linear era of the hybrid inflation waterfall. The spectrum of this contribution
peaks at some wavenumber , and goes like for , making it
typically negligible on cosmological scales. The scale can be outside the
horizon at the end of inflation, in which case \zeta=- (g^2 - \vev{g^2}) with
gaussian. Taking this into account, the cosmological bound on the abundance
of black holes is likely to be satisfied if the curvaton mass much bigger
than the Hubble parameter , but is likely to be violated if m\lsim H.
Coming to the contribution to from the rest of the waterfall, we are
led to consider the use of the `end-of-inflation' formula, giving the
contribution to generated during a sufficiently sharp transition from
nearly-exponential inflation to non-inflation, and we state for the first time
the criterion for the transition to be sufficiently sharp. Our formulas are
applied to supersymmetric GUT inflation and to supernatural/running-mass
inflationComment: very minor change
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