256 research outputs found
Identification of two new HMXBs in the LMC: a 2013 s pulsar and a probable SFXT
We report on the X-ray and optical properties of two high-mass X-ray binary
systems located in the Large Magellanic Cloud (LMC). Based on the obtained
optical spectra, we classify the massive companion as a supergiant star in both
systems. Timing analysis of the X-ray events collected by XMM-Newton revealed
the presence of coherent pulsations (spin period 2013 s) for XMMU
J053108.3-690923 and fast flaring behaviour for XMMU J053320.8-684122. The
X-ray spectra of both systems can be modelled sufficiently well by an absorbed
power-law, yielding hard spectra and high intrinsic absorption from the
environment of the systems. Due to their combined X-ray and optical properties
we classify both systems as SgXRBs: the 19 confirmed X-ray pulsar
and a probable supergiant fast X-ray transient in the LMC, the second such
candidate outside our Galaxy.Comment: 12 pages, 10 figures, accepted for publication in MNRA
Engineering of composite metallic microfibers towards development of plasmonic devices for sensing applications
The paper discusses the analysis of tapered hybrid composite microfibers based on a metal-core and dielectric-cladding composite material system. Its advantages over the pure metal tips conventionally used, are the inherent enhanced environmental robustness due to inert borosilicate cladding and the capability of multiple excitation of the tapered nanowire through the length of the fiber due to the enabled total internal reflection at the borosilicate/air interface. Simulations through finite element method (FEM) have demonstrated an improved field enhancement at the tapered region of such microfibers. Furthermore, experimental results on tapering in copper based microfibers together with light coupling and propagation studies will be demonstrated revealing the potential for the development of plasmonic devices for sensing applications
A review of methods for addressing components of interventions in meta-analysis
Many healthcare interventions are complex, consisting of multiple, possibly interacting, components. Several methodological articles addressing complex interventions in the metaanalytical context have been published. We hereby provide an overview of methods used to evaluate the effects of complex interventions with meta-analytical models. We summarized the methodology, highlighted new developments, and described the benefits, drawbacks, and potential challenges of each identified method. We expect meta-analytical methods focusing on components of several multicomponent interventions to become increasingly popular due to recently developed, easy-to-use, software tools that can be used to conduct the relevant analyses. The different meta-analytical methods are illustrated through two examples comparing psychotherapies for panic disorder. Copyright
Aperture effects on the oxygen abundance determinations from CALIFA data
This paper aims at providing aperture corrections for emission lines in a
sample of spiral galaxies from the Calar Alto Legacy Integral Field Area Survey
(CALIFA) database. In particular, we explore the behavior of the
log([OIII]5007/Hbeta)/([NII]6583/Halpha) (O3N2) and log[NII]6583/Halpha (N2)
flux ratios since they are closely connected to different empirical
calibrations of the oxygen abundances in star forming galaxies.
We compute median growth curves of Halpha, Halpha/Hbeta, O3N2 and N2 up to
2.5R_50 and 1.5 disk R_eff. The growth curves simulate the effect of observing
galaxies through apertures of varying radii. The median growth curve of the
Halpha/Hbeta ratio monotonically decreases from the center towards larger
radii, showing for small apertures a maximum value of ~10% larger than the
integrated one. The median growth curve of N2 shows a similar behavior,
decreasing from the center towards larger radii. No strong dependence is seen
with the inclination, morphological type and stellar mass for these growth
curves. Finally, the median growth curve of O3N2 increases monotonically with
radius. However, at small radii it shows systematically higher values for
galaxies of earlier morphological types and for high stellar mass galaxies.
Applying our aperture corrections to a sample of galaxies from the SDSS
survey at 0.02<=z<=0.3 shows that the average difference between fiber-based
and aperture corrected oxygen abundances, for different galaxy stellar mass and
redshift ranges, reaches typically to ~11%, depending on the abundance
calibration used. This average difference is found to be systematically biased,
though still within the typical uncertainties of oxygen abundances derived from
empirical calibrations. Caution must be exercised when using observations of
galaxies for small radii (e.g. below 0.5R_eff) given the high dispersion shown
around the median growth curves.Comment: Accepted for publication in Ap
The hunt for extraterrestrial high-energy neutrino counterparts
The origin of Petaelectronvolt (PeV) astrophysical neutrinos is fundamental
to our understanding of the high-energy Universe. Apart from the technical
challenges of operating detectors deep below ice, oceans, and lakes, the
phenomenological challenges are even greater than those of gravitational waves;
the sources are unknown, hard to predict, and we lack clear signatures.
Neutrino astronomy therefore represents the greatest challenge faced by the
astronomy and physics communities thus far. The possible neutrino sources range
from accretion disks and tidal disruption events, to relativistic jets and
galaxy clusters with blazar TXS~0506+056 the most compelling association thus
far. Since that association, immense effort has been put into proving or
disproving that jets are indeed neutrino emitters, but to no avail. By
generating simulated neutrino counterpart samples, we explore the potential of
detecting a significant correlation of neutrinos with jets from active galactic
nuclei. We find that, given the existing challenges, even our best experiments
could not have produced a result. Larger programs over the next few
years will be able to detect a significant correlation only if the brightest
radio sources, rather than all jetted active galactic nuclei, are neutrino
emitters. We discuss the necessary strategies required to steer future efforts
into successful experiments.Comment: 8 pages, 1 figure, 1 table, accepted for publication in A&
The prognostic significance of Cdc6 and Cdt1 in breast cancer
DNA replication is a critical step in cell proliferation. Overexpression of MCM2-7 genes correlated with poor prognosis in breast cancer patients. However, the roles of Cdc6 and Cdt1, which work with MCMs to regulate DNA replication, in breast cancers are largely unknown. In the present study, we have shown that the expression levels of Cdc6 and Cdt1 were both significantly correlated with an increasing number of MCM2-7 genes overexpression. Both Cdc6 and Cdt1, when expressed in a high level, alone or in combination, were significantly associated with poorer survival in the breast cancer patient cohort (nâ=â1441). In line with this finding, the expression of Cdc6 and Cdt1 was upregulated in breast cancer cells compared to normal breast epithelial cells. Expression of Cdc6 and Cdt1 was significantly higher in ER negative breast cancer, and was suppressed when ER signalling was inhibited either by tamoxifen in vitro or letrozole in human subjects. Importantly, breast cancer patients who responded to letrozole expressed significantly lower Cdc6 than those patients who did not respond. Our results suggest that Cdc6 is a potential prognostic marker and therapeutic target in breast cancer patients
Identifying crop variants with high resistant starch content to maintain healthy glucose homeostasis
Identifying dietary tools that prevent disordered insulin secretion from pancreatic ÎČâcells is an attractive strategy to combat the increasing prevalence of type 2 diabetes. Dietary resistant starch has been linked to improvements in the function of ÎČâcells, possibly via increased colonic fermentation and production of shortâchain fatty acids (SCFAs). Increasing the resistant starch content of commonly consumed foods could therefore maintain glucose homeostasis at the population level. As part of Biotechnology and Biological Sciences Research Council (BBSRC) Diet and Health Research Industry Club (DRINC) initiative, variants of Pisum sativum L. (pea) are being investigated to identify the features of pea starch that make it resistant to digestion and available for colonic fermentation and SCFA production. Parallel in vitro and in vivo studies are being conducted using both whole pea seeds and pea flour to facilitate a better understanding of how cells in the pea cotyledons are affected by processing and, in turn, how this influences starch digestibility. Trials in human volunteers are being used to monitor a full spectrum of shortâ and longâterm physiological responses relevant to pancreatic ÎČâcell function and glucose homeostasis. This project is providing new insights into variants of crops that are associated with the specific types of resistant starch that provide the best protection against defects in insulin secretion and function
Neutrinos, Cosmic Rays and the MeV Band
The possible association of the blazar TXS 0506+056 with a high-energy
neutrino detected by IceCube holds the tantalizing potential to answer three
astrophysical questions: 1. Where do high-energy neutrinos originate? 2. Where
are cosmic rays produced and accelerated? 3. What radiation mechanisms produce
the high-energy {\gamma}-rays in blazars? The MeV gamma-ray band holds the key
to these questions, because it is an excellent proxy for photo-hadronic
processes in blazar jets, which also produce neutrino counterparts. Variability
in MeV gamma-rays sheds light on the physical conditions and mechanisms that
take place in the particle acceleration sites in blazar jets. In addition,
hadronic blazar models also predict a high level of polarization fraction in
the MeV band, which can unambiguously distinguish the radiation mechanism.
Future MeV missions with a large field of view, high sensitivity, and
polarization capabilities will play a central role in multi-messenger
astronomy, since pointed, high-resolution telescopes will follow neutrino
alerts only when triggered by an all-sky instrument.Comment: White paper submitted to the Astro2020 Decadal Surve
Performing Values Practices and Grassroots Organizing: The Case of Solidarity Economy Initiatives in Greece
This article discusses solidarity economy initiatives as instances of grassroots organizing, and explores how âvalues practicesâ are performed collectively during times of crisis. In focusing on how power, discourse and subjectivities are negotiated in the everyday practices of grassroots exchange networks (GENs) in crisis-stricken Greece, the study unveils and discusses three performances of values practices, namely mobilization of values, re-articulation of social relations, and sustainable living. Based on these findings, and informed by theoretical analyses of performativity, we propose a framework for studying the production and reproduction of values in the context of GENs, and the role of values in organizing alternatives
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