1,401 research outputs found
Spacetime Fermions in Light-cone Gauge Superstring Field Theory and Dimensional Regularization
We consider the dimensional regularization of the light-cone gauge type II
superstring field theories in the NSR formalism. In the previous work, we have
calculated the tree-level amplitudes with external lines in the (NS,NS) sector
using the regularization and shown that the desired results are obtained
without introducing contact term interactions. In this work, we study the
tree-level amplitudes with external lines in the Ramond sector. In order to
deal with them, we propose a worldsheet theory to be used instead of that for
the naive dimensional regularization. With the worldsheet theory, we regularize
and define the tree-level amplitudes by analytic continuation. We show that the
results coincide with those of the first quantized formulation.Comment: 28 pages, 5 figures; v2: more details of our manipulations in
subsection 3.2 added, figures and references added; v3: clarifications adde
The Muqawama (“Resistance”) Narrative, and its Detractors, in Contemporary Mauritania
UID/ANT/04038/2019Since 2012, when broadcasting licenses were granted to various private television and radio stations in Mauritania, the controversy around the Battle of Um Tounsi (and Mauritania’s colonial past more generally) has grown substantially. One of the results of this unprecedented level of media freedom has been the propagation of views defending the Mauritanian resistance (muqawama in Arabic) to French colonization. On the one hand, verbal and written accounts have emerged which paint certain groups and actors as French colonial power sympathizers. At the same time, various online publications have responded by seriously questioning the very existence of a structured resistance to colonization. This article, drawing predominantly on local sources, highlights the importance of this controversy in studying the western Saharan region social model and its contemporary uses.publishersversionpublishe
Lifestyle, Fitness and Health Promotion Initiative of the University of Ilorin, Nigeria: An Educational Media Intervention
This study examined the health promotion initiative introduced by the Management of the University of Ilorin, Ngeria. In an attempt to ensure stress free academic society that would boost staff productivity and longevity, the university invested heavily on a number of lifestyle, fitness and health promotion initiatives. Descriptive research design of the survey type was adopted for this study. Staff and registered students of the University for 2010/2011 and 2011/2012 academic sessions were sampled. A total of one thousand randomly selected academic, non- academic staff and students from the twelve faculties with the exception of postgraduate students of the university participated in the study. A structured questionnaire validated and pilot tested with reliability co-efficient of 63r was used for data collection. The data collected were subjected to descriptive and inferential statistics of chi-square and Analysis of variance at 0.05 alpha level of significance. The two postulated hypotheses for the study were rejected. The result indicated a significant hyperthy and underutilization of multi-million naira fitness equipment procured for staff and students; it also revealed low turn-out at the monthly Unilorin walk a-fitness programme for staff and students of the university. The monthly health talk organized by the health education group on causes, signs and symptoms of hypertension, diabetes and other diseases also suffered from the same low turn-out of staff and students of the university among others. The authors suggested a conducive academic environment that will enable the staff to have time to take care of their health, Unilorin walk should be organized on faculty/departmental basis as a university-wide programme will not bring the desire result. More publicity should be carried out so as to boost staff and students attendance at the monthly health talk.Key words: Lifestyle; Health Promotion; Physical Fitness; Hypo-kinetics Diseases; Physical inactivit
Stellar Kinematics of the Andromeda II Dwarf Spheroidal Galaxy
We present kinematical profiles and metallicity for the M31 dwarf spheroidal
(dSph) satellite galaxy Andromeda II (And II) based on Keck DEIMOS spectroscopy
of 531 red giant branch stars. Our kinematical sample is among the largest for
any M31 satellite and extends out to two effective radii (r_eff = 5.3' = 1.1
kpc). We find a mean systemic velocity of -192.4+-0.5 km/s and an average
velocity dispersion of sigma_v = 7.8+-1.1 km/s. While the rotation velocity
along the major axis of And II is nearly zero (<1 km/s), the rotation along the
minor axis is significant with a maximum rotational velocity of v_max=8.6+-1.8
km/s. We find a kinematical major axis, with a maximum rotational velocity of
v_max=10.9+-2.4 km/s, misaligned by 67 degrees to the isophotal major axis. And
II is thus the first dwarf galaxy with evidence for nearly prolate rotation
with a v_max/sigma_v = 1.1, although given its ellipticity of epsilon = 0.10,
this object may be triaxial. We measured metallicities for a subsample of our
data, finding a mean metallicity of [Fe/H] = -1.39+- 0.03 dex and an internal
metallicity dispersion of 0.72+-0.03 dex. We find a radial metallicity gradient
with metal-rich stars more centrally concentrated, but do not observe a
significant difference in the dynamics of two metallicity populations. And II
is the only known dwarf galaxy to show minor axis rotation making it a unique
system whose existence offers important clues on the processes responsible for
the formation of dSphs.Comment: 14 pages, 10 figures, 4 tables, accepted for publication in Ap
Model-based analysis uncovers mutations altering autophagy selectivity in human cancer
Autophagy can selectively target protein aggregates, pathogens, and dysfunctional organelles for the lysosomal degradation. Aberrant regulation of autophagy promotes tumorigenesis, while it is far less clear whether and how tumor-specific alterations result in autophagic aberrance. To form a link between aberrant autophagy selectivity and human cancer, we establish a computational pipeline and prioritize 222 potential LIR (LC3-interacting region) motif-associated mutations (LAMs) in 148 proteins. We validate LAMs in multiple proteins including ATG4B, STBD1, EHMT2 and BRAF that impair their interactions with LC3 and autophagy activities. Using a combination of transcriptomic, metabolomic and additional experimental assays, we show that STBD1, a poorly-characterized protein, inhibits tumor growth via modulating glycogen autophagy, while a patient-derived W203C mutation on LIR abolishes its cancer inhibitory function. This work suggests that altered autophagy selectivity is a frequently-used mechanism by cancer cells to survive during various stresses, and provides a framework to discover additional autophagy-related pathways that influence carcinogenesis
Phage-mediated horizontal transfer of a Staphylococcus aureus virulence-associated genomic island
Staphylococcus aureus is a major pathogen of humans and animals. The capacity of S. aureus to adapt to different host species and tissue types is strongly influenced by the acquisition of mobile genetic elements encoding determinants involved in niche adaptation. The genomic islands νSaα and νSaβ are found in almost all S. aureus strains and are characterized by extensive variation in virulence gene content. However the basis for the diversity and the mechanism underlying mobilization of the genomic islands between strains are unexplained. Here, we demonstrated that the genomic island, νSaβ, encoding an array of virulence factors including staphylococcal superantigens, proteases, and leukotoxins, in addition to bacteriocins, was transferrable in vitro to human and animal strains of multiple S. aureus clones via a resident prophage. The transfer of the νSaβ appears to have been accomplished by multiple conversions of transducing phage particles carrying overlapping segments of the νSaβ. Our findings solve a long-standing mystery regarding the diversification and spread of the genomic island νSaβ, highlighting the central role of bacteriophages in the pathogenic evolution of S. aureus
Tumor innate immunity primed by specific interferon-stimulated endogenous retroviruses.
Mesenchymal tumor subpopulations secrete pro-tumorigenic cytokines and promote treatment resistance1-4. This phenomenon has been implicated in chemorefractory small cell lung cancer and resistance to targeted therapies5-8, but remains incompletely defined. Here, we identify a subclass of endogenous retroviruses (ERVs) that engages innate immune signaling in these cells. Stimulated 3 prime antisense retroviral coding sequences (SPARCS) are oriented inversely in 3' untranslated regions of specific genes enriched for regulation by STAT1 and EZH2. Derepression of these loci results in double-stranded RNA generation following IFN-γ exposure due to bi-directional transcription from the STAT1-activated gene promoter and the 5' long terminal repeat of the antisense ERV. Engagement of MAVS and STING activates downstream TBK1, IRF3, and STAT1 signaling, sustaining a positive feedback loop. SPARCS induction in human tumors is tightly associated with major histocompatibility complex class 1 expression, mesenchymal markers, and downregulation of chromatin modifying enzymes, including EZH2. Analysis of cell lines with high inducible SPARCS expression reveals strong association with an AXL/MET-positive mesenchymal cell state. While SPARCS-high tumors are immune infiltrated, they also exhibit multiple features of an immune-suppressed microenviroment. Together, these data unveil a subclass of ERVs whose derepression triggers pathologic innate immune signaling in cancer, with important implications for cancer immunotherapy
Attention-dependent modulation of cortical taste circuits revealed by granger causality with signal-dependent noise
We show, for the first time, that in cortical areas, for example the insular, orbitofrontal, and lateral prefrontal cortex, there is signal-dependent noise in the fMRI blood-oxygen level dependent (BOLD) time series, with the variance of the noise increasing approximately linearly with the square of the signal. Classical Granger causal models are based on autoregressive models with time invariant covariance structure, and thus do not take this signal-dependent noise into account. To address this limitation, here we describe a Granger causal model with signal-dependent noise, and a novel, likelihood ratio test for causal inferences. We apply this approach to the data from an fMRI study to investigate the source of the top-down attentional control of taste intensity and taste pleasantness processing. The Granger causality with signal-dependent noise analysis reveals effects not identified by classical Granger causal analysis. In particular, there is a top-down effect from the posterior lateral prefrontal cortex to the insular taste cortex during attention to intensity but not to pleasantness, and there is a top-down effect from the anterior and posterior lateral prefrontal cortex to the orbitofrontal cortex during attention to pleasantness but not to intensity. In addition, there is stronger forward effective connectivity from the insular taste cortex to the orbitofrontal cortex during attention to pleasantness than during attention to intensity. These findings indicate the importance of explicitly modeling signal-dependent noise in functional neuroimaging, and reveal some of the processes involved in a biased activation theory of selective attention
Genetic Diversity of Staphylocoagulase Genes (coa): Insight into the Evolution of Variable Chromosomal Virulence Factors in Staphylococcus aureus
. Although SCs have been classified into 10 serotypes based on the differences in the antigenicity, genetic bases for their diversities and relatedness to chromosome types are poorly understood. type except for the cases of CC1 and CC8, which contained two and three different SC types, respectively. loci, resulting in the carriage of the combinations of allotypically different important virulence determinants in staphylococcal chromosome
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