4,176 research outputs found
Reducing orbital eccentricity of precessing black-hole binaries
Building initial conditions for generic binary black-hole evolutions without
initial spurious eccentricity remains a challenge for numerical-relativity
simulations. This problem can be overcome by applying an eccentricity-removal
procedure which consists in evolving the binary for a couple of orbits,
estimating the eccentricity, and then correcting the initial conditions. The
presence of spins can complicate this procedure. As predicted by post-Newtonian
theory, spin-spin interactions and precession prevent the binary from moving
along an adiabatic sequence of spherical orbits, inducing oscillations in the
radial separation and in the orbital frequency. However, spin-induced
oscillations occur at approximately twice the orbital frequency, therefore they
can be distinguished from the initial spurious eccentricity, which occurs at
approximately the orbital frequency. We develop a new removal procedure based
on the derivative of the orbital frequency and find that it is successful in
reducing the eccentricity measured in the orbital frequency to less than 0.0001
when moderate spins are present. We test this new procedure using
numerical-relativity simulations of binary black holes with mass ratios 1.5 and
3, spin magnitude 0.5 and various spin orientations. The numerical simulations
exhibit spin-induced oscillations in the dynamics at approximately twice the
orbital frequency. Oscillations of similar frequency are also visible in the
gravitational-wave phase and frequency of the dominant mode.Comment: 17 pages, 11 figures, fixed typo
Technical report series on global modeling and data assimilation. Volume 1: Documentation of the Goddard Earth Observing System (GEOS) General Circulation Model, version 1
This technical report documents Version 1 of the Goddard Earth Observing System (GEOS) General Circulation Model (GCM). The GEOS-1 GCM is being used by NASA's Data Assimilation Office (DAO) to produce multiyear data sets for climate research. This report provides a documentation of the model components used in the GEOS-1 GCM, a complete description of model diagnostics available, and a User's Guide to facilitate GEOS-1 GCM experiments
Perceptions of Women and Men Leaders Following 360‐Degree Feedback Evaluations
In this study, researchers used a customized 360‐degree method to examine the frequency with which 1,546 men and 721 women leaders perceived themselves and were perceived by colleagues as using 10 relational and 10 task‐oriented leadership behaviors, as addressed in the Management‐Leadership Practices Inventory (MLPI). As hypothesized, men and women leaders, as well as their supervisors, employees, and peers, perceived women leaders to employ nine of the 10 relational leadership behaviors significantly more frequently than men leaders. Additionally, the employees' perceptions of their women leaders' use of task‐oriented behaviors were significantly higher when compared to similar assessments from the employees of men leaders. However, the leaders as well as their supervisors and peers perceived men and women leaders' use of task‐oriented behaviors as approximately equal. Broader implications of these findings are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97470/1/21134_ftp.pd
Childhood maltreatment and adult psychopathology: pathways to hypothalamic-pituitary-adrenal axis dysfunction
OBJECTIVE: The aim of this paper was to examine the relationship between childhood maltreatment and adult psychopathology, as reflected in hypothalamic-pituitary-adrenal axis dysfunction. METHOD: A selective review of the relevant literature was undertaken in order to identify key and illustrative research findings. RESULTS: There is now a substantial body of preclinical and clinical evidence derived from a variety of experimental paradigms showing how early-life stress is related to hypothalamic-pituitary-adrenal axis function and psychological state in adulthood, and how that relationship can be modulated by other factors. DISCUSSION: The risk for adult psychopathology and hypothalamic-pituitary-adrenal axis dysfunction is related to a complex interaction among multiple experiential factors, as well as to susceptibility genes that interact with those factors. Although acute hypothalamic-pituitary-adrenal axis responses to stress are generally adaptive, excessive responses can lead to deleterious effects. Early-life stress alters hypothalamic-pituitary-adrenal axis function and behavior, but the pattern of hypothalamic-pituitary-adrenal dysfunction and psychological outcome in adulthood reflect both the characteristics of the stressor and other modifying factors. CONCLUSION: Research to date has identified multiple determinants of the hypothalamic-pituitary-adrenal axis dysfunction seen in adults with a history of childhood maltreatment or other early-life stress. Further work is needed to establish whether hypothalamic-pituitary-adrenal axis abnormalities in this context can be used to develop risk endophenotypes for psychiatric and physical illnesses.OBJETIVO: A meta deste artigo foi a de estudar as relações ente maus-tratos na infância e psicopatologia no adulto, como reflexo de uma disfunção do eixo hipotálamo-pituitária-adrenal. MÉTODO: Uma revisão seletiva da literatura relevante foi feita para identificar achados-chave e ilustrativos. RESULTADOS: Existe atualmente um volume significativo de achados científicos pré-clínicos e clínicos derivados de paradigmas experimentais, que demonstram que o estresse precoce está relacionado à função do eixo hipotálamo-pituitária-adrenal e a estados psicológicos no indivíduo adulto, e como esta relação pode ser modulada por outros fatores. DISCUSSÃO: O risco para o desenvolvimento de psicopatologia no adulto e disfunções do eixo hipotálamo-pituitária-adrenal está relacionado à complexa interação de múltiplos fatores vivenciais, assim como a genes que levam a uma susceptibilidade, que interagem com estes fatores. Embora as respostas agudas do eixo hipotálamo-pituitária-adrenal sejam geralmente adaptativas, as respostas excessivas podem levar a efeitos deletérios. O estresse precoce pode alterar a função do eixo hipotálamo-pituitária-adrenal assim como o comportamento, porém, o padrão da disfunção do eixo hipotálamo-pituitária-adrenal e a evolução psicológica na vida adulta refletem ambas as características do estressor e outros fatores modificadores. CONCLUSÃO: A pesquisa atual identificou múltiplos determinantes da disfunção do eixo hipotálamo-pituitária-adrenal encontrados em adultos com história de maus-tratos na infância ou outros estressores precoces. Trabalhos futuros são necessários para estabelecer se as anormalidades do eixo hipotálamo-pituitária-adrenal neste contexto podem ser usadas para o desenvolvimento de endofenótipos de risco para doenças físicas ou psiquiátricas.Universidade Federal de São Paulo (UNIFESP) Instituto PROVEBrown University Warren Alpert Medical School Butler HospitalUNIFESP, Instituto PROVESciEL
Large-Scale Atmospheric Transport in GEOS Replay Simulations
Offline chemical transport models (CTMs) have traditionally been used to perform studies of atmospheric chemistry in a fixed dynamical environment. An alternative to using CTMs is to constrain the flow in a general circulation model using winds from meteorological analyses. The Goddard Earth Observing System (GEOS) "replay" approach involves reading in analyzed fields every six hours and recomputing the analysis increments, which are applied as a forcing to the meteorology at every model time step. Unlike in CTM, all of the subgrid-scale processes are recalculated on-line so that they are consistent with the large-scale analysis fields, similar in spirit to "nudged" simulations, in which the online meteorology is relaxed to the analysis. Here we compare the transport of idealized tracers in different replay simulations constrained with meteorological fields taken from The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA-2). We show that there are substantial differences in their large-scale stratospheric transport, depending on whether analysis fields or assimilated fields are used. Replay simulations constrained with the instantaneous analysis fields produce stratospheric mean age values that are up to 30% too young relative to observations; by comparison, simulations constrained with the time-averaged assimilated fields produce more credible stratospheric transport. Our study indicates that care should be taken to correctly configure the model when the replay technique is used to simulate stratospheric composition
The extent of metalloproteinase-mediated LAG3 cleavage limits the efficacy of PD1 blockade
Inhibitory receptors control immune responses preventing exacerbated T cell activation and the onset of autoimmunity; however, they also limit antitumor immunity. Enhanced co-expression of PD1 and LAG3 phenotypically mark functionally exhausted tumor-specific T cells, with dual PD1/LAG3 blockade synergistically limiting tumor growth in murine models. Like PD1, LAG3 expression is induced on activated T cells to negatively regulate T cell activation and proliferation and LAG3 is also required for maximal regulatory T (Treg) cell function. However, LAG3 expression and function is itself regulated by cell surface cleavage of the transmembrane domain connecting peptide by ADAM10 and ADAM17 metalloproteinase-disintegrins. This releases soluble LAG3, of which no biological function has been found to date. To investigate the impact of LAG3 cleavage on T cells within tumors, a non-cleavable LAG3 mouse (LAG3.NC) was generated in which exons 7 and 8 of Lag3, including the connecting peptide, is deleted in Cre-expressing cells. These exons are replaced and modified so that the connecting peptide is absent preventing LAG3 cleavage. LAG3.NC CD4Cre mice (with non-cleavable LAG3 expressed on all CD8+ and CD4+ T cells, including Tregs) and LAG3.NC E8ICre mice (restricted to CD8+ T cells only) exhibit enhanced expression of LAG3 on the respective T cell subsets in B16-F10 or MC38 tumors, co-expressing with PD1. Despite increased LAG3 expression, no difference in B16-F10 or MC38 tumor growth was observed in either LAG3.NC CD4Cre or LAG3.NC E8ICre mice compared with wild-type littermates. Upon therapeutic administration of anti-PD1 antibody (clone G4), MC38 tumor-bearing wild-type mice show significant tumor regression and 40% become tumor-free resulting in long-term survival. LAG3.NC CD4Cre mice were resistant to anti-PD1 therapy and succumb to tumor growth. However, anti-PD1 mediated tumor regression and long-term survival in LAG3.NC E8ICre mice. Analysis of re-stimulated CD8+ TILs isolated from LAG3.NC CD4Cre mice did not show enhanced IFN-gamma and TNF-alpha production following anti-PD1 therapy, which was observed with LAG3.NC E8ICre mice or wild-type littermates. Moreover, reduced proliferation was observed for all T cell subsets in LAG3.NC CD4Cre mice compared with LAG3.NC E8ICre and wild-type littermates following anti-PD1 treatment. As LAG3.NC CD4Cre, but not LAG3.NC E8ICre mice, are resistant to the favorable antitumor immune effects induced by anti-PD1, this suggests that enhanced LAG3 expression on CD4+ T cells or Tregs may act as a barrier to effective anti-PD1 immunotherapy. LAG3.NC mice crossed with Cre that restricts non-cleavable LAG3 to Tregs (Foxp3yfpiCre) or CD4+ T cells (ThPOKCre) are currently under analysis
Magnetic Resonance Imaging of Plantar Plate Rupture
Degenerative plantar plate failure is an under-recognized cause of lesser metatarsalgia. We performed magnetic resonance imaging (MRI) with a small receiver coil in 13 patients in whom plantar plate ruptures of the second or third metatarsophalangeal joint were clinically suspected. In eight patients, MRI showed focal hyperintensity in the plantar plate that was interpreted as a rupture of the plate. Ruptures were confirmed in all five patients who underwent an operative procedure to treat the unstable, painful metatarsophalangeal joint. MRI is a noninvasive technique that can visualize plantar plate abnormalities and aid the clinical evaluation of problematic lesser metatarsalgia
Error-analysis and comparison to analytical models of numerical waveforms produced by the NRAR Collaboration
The Numerical-Relativity-Analytical-Relativity (NRAR) collaboration is a
joint effort between members of the numerical relativity, analytical relativity
and gravitational-wave data analysis communities. The goal of the NRAR
collaboration is to produce numerical-relativity simulations of compact
binaries and use them to develop accurate analytical templates for the
LIGO/Virgo Collaboration to use in detecting gravitational-wave signals and
extracting astrophysical information from them. We describe the results of the
first stage of the NRAR project, which focused on producing an initial set of
numerical waveforms from binary black holes with moderate mass ratios and
spins, as well as one non-spinning binary configuration which has a mass ratio
of 10. All of the numerical waveforms are analysed in a uniform and consistent
manner, with numerical errors evaluated using an analysis code created by
members of the NRAR collaboration. We compare previously-calibrated,
non-precessing analytical waveforms, notably the effective-one-body (EOB) and
phenomenological template families, to the newly-produced numerical waveforms.
We find that when the binary's total mass is ~100-200 solar masses, current EOB
and phenomenological models of spinning, non-precessing binary waveforms have
overlaps above 99% (for advanced LIGO) with all of the non-precessing-binary
numerical waveforms with mass ratios <= 4, when maximizing over binary
parameters. This implies that the loss of event rate due to modelling error is
below 3%. Moreover, the non-spinning EOB waveforms previously calibrated to
five non-spinning waveforms with mass ratio smaller than 6 have overlaps above
99.7% with the numerical waveform with a mass ratio of 10, without even
maximizing on the binary parameters.Comment: 51 pages, 10 figures; published versio
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