2,379 research outputs found
The Fourth-Century AD Expansion of the Graeco-Roman Settlement of Karanis (Kom Aushim) in the Northern Fayum*
The Graeco-Roman town of Karanis, founded during the Ptolemaic Period in the north-eastern Fayum in the third century bc and long thought to have been abandoned in the third century ad actually saw a substantial expansion during the fourth century AD. With the creation of an 3 extension towards the west and the expansion of the eastern part, the town grew in both directions. We argue that this expansion may be related to a sudden rise of the water level in Lake Moeris (Lake Qarun), perhaps linked to a catastrophic dam breach in the eastern part of the Fayum, and the subsequent relocation of the inhabitants of the low-lying settlements north and east of the lake
Around 200 new X-ray binary IDs from 13 years of Chandra observations of the M31 center
We have created 0.3--10 keV, 13 year, unabsorbed luminosity lightcurves for
528 X-ray sources in the central 20' of M31. We have 174 Chandra observations
spaced at ~1 month intervals thanks to our transient monitoring program, deeper
observations of the M31 nucleus, and some public data from other surveys. We
created 0.5--4.5 keV structure functions (SFs) for each source, for comparison
with the ensemble structure function of AGN. We find 220 X-ray sources with
luminosities > ~1E+35 erg/s that have SFs with significantly more variability
than the ensemble AGN SF, and are likely X-ray binaries (XBs). A further 30
X-ray sources were identified as XBs using other methods. We therefore have 250
probable XBs in total, including ~200 new identifications. This result
represents great progress over the ~50 XBs and ~40 XB candidates previously
identified out of the ~2000 X-ray sources within the D_25 region of M31; it
also demonstrates the power of SF analysis for identifying XBs in external
galaxies. We also identify a new transient black hole candidate, associated
with the M31 globular cluster B128.Comment: Accepted for publication in ApJ; 20 pages, 7 figures; Tables 1 and 2
continue after the references (8 pages
Four new black hole candidates identified in M31 globular clusters with Chandra and XMM-Newton
We have identified four new black hole candidates in M31 globular clusters
using 123 Chandra, and 4 XMM-Newton observations of the M31 central region. The
X-ray source associated with Bo 163 (XB163) is a recurrent transient, with the
highest luminosity ~1.4E+38 erg/s, considerably brighter than any outbursts
from the neutron star transients Aql X-1 or 4U 1608-452; the outburst
apparently started ~45 days earlier than the observed peak, hence the
luminosity could have been considerably higher. We identified XB082, XB153 and
XB185 as BHCs by observing "low state" emission spectra at luminosities that
exceed the threshold for neutron star binaries. The probability that these are
neutron star systems with anisotropic emission beamed toward us is <4E-4, and
their variability suggests emission from a single source. We therefore conclude
that these systems likely contain black holes rather than neutron stars. We
have now identified 4 persistently bright BHCs in the region; the probability
that these are all background AGN is <1E-20. According to theory, the donors
could be tidally captured main sequence stars, or white dwarves in
ultra-compact binaries. We find that GCs that are particularly massive (XB082)
or metal rich (XB144) can host bright X-ray sources in addition to those that
are both (XB163). Our method may reveal BHCs in other bright X-ray sources.Comment: Accepted for publication in ApJ. 17 pages, 5 figure
Fungal dissemination by housefly (Musca domestica L.) and contamination of food commodities in rural areas of South Africa
Abstract: Several insects that act as vectors, including houseflies (Musca domestica L.), are often considered to be an important source of fungal contamination in human foods.Houseflies are also involved in the transmission of bacterial pathogens that may pose a serious hazard to human health. Thus, the rural population of South Africa, as typified by that in the Gauteng Province investigated in this study, is at high risk from fungal exposure disseminated by houseflies and it is therefore important to assess the role of flies in contaminating various food commodities. Eighty four samples of houseflies (captured fromhouseholds and pit toilets)were studied for their potential to carry fungal spores into food commodities. The fungi occurring in samples of rawmaize (15) and porridge (19)were also assessed. Fungal isolates were identified based on morphological characteristics by conventional identification methods. Fifteen genera of fungi were isolated and identified, of which Aspergillus, Fusarium, Penicillium, Cladosporium, Moniliella and Mucor were the most prevalent in all three sample types analysed. The incidence rates of fungal contamination per total fungal count isolated in houseflies, maize and porridge were recorded with mean fungal load of 2 × 108 CFU/ml, 1 × 107 CFU/g and 2 × 107 CFU/g respectively. Additionally, A. flavus, A. parasiticus, F. verticillioides, F. proliferatum, P. verrucosum, P. aurantiogriseum and M. suaveolens were the most frequent fungal isolates in houseflies with incidence rate of 34%, 11%, 27%, 21%, 22%, 17% and 32% respectively. F. verticillioides, A. flavus, A. niger and P. oslonii were the most prevalent species contaminating porridge and maize with incidence rate of 23%, 32%, 16% and 28% in maize samples,while incidence rates of 59%, 15% and 29% were recorded in porridge samples with the exception of F. verticillioides. The prevalence of these genera of fungi may pose serious health risks
Edge-based compartmental modelling of an SIR epidemic on a dual-layer static-dynamic multiplex network with tunable clustering
The duration, type and structure of connections between individuals in real-world populations play a crucial role in how diseases invade and spread. Here, we incorporate the aforementioned heterogeneities into a model by considering a dual-layer static-dynamic multiplex network. The static network layer affords tunable clustering and describes an individual’s permanent community structure. The dynamic network layer describes the transient connections an individual makes with members of the wider population by imposing constant edge rewiring. We follow the edge-based compartmental modelling approach to derive equations describing the evolution of a susceptible - infected - recovered (SIR) epidemic spreading through this multiplex network of individuals. We derive the basic reproduction number, measuring the expected number of new infectious cases caused by a single infectious individual in an otherwise susceptible population. We validate model equations by showing convergence to pre-existing edge-based compartmental model equations in limiting cases and by comparison with stochastically simulated epidemics. We explore the effects of altering model parameters and multiplex network attributes on resultant epidemic dynamics. We validate the basic reproduction number by plotting its value against associated final epidemic sizes measured from simulation and predicted by model equations for a number of setups. Further, we explore the effect of varying individual model parameters on the basic reproduction number. We conclude with a discussion of the significance and interpretation of the model and its relation to existing research literature. We highlight intrinsic limitations and potential extensions of the present model and outline future research considerations, both experimental and theoretical
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Inhibition of adenovirus serotype 14 infection by octadecyloxyethyl esters of (S)-[(3-hydroxy-2-phosphonomethoxy)propyl]- nucleosides in vitro.
On September 22, 2008, a physician on Prince of Wales Island, Alaska, notified the Alaska Department of Health and Social Services (ADHSS) of an unusually high number of adult patients with recently diagnosed pneumonia (n = 10), including three persons who required hospitalization and one who died. ADHSS and CDC conducted an investigation to determine the cause and distribution of the outbreak, identify risk factors for hospitalization, and implement control measures. This report summarizes the results of that investigation, which found that the outbreak was caused by adenovirus 14 (Ad14), an emerging adenovirus serotype in the United States that is associated with a higher rate of severe illness compared with other adenoviruses. Among the 46 cases identified in the outbreak from September 1 through October 27, 2008, the most frequently observed characteristics included the following: male (70%), Alaska Native (61%), underlying pulmonary disease (44%), aged > or = 65 years (26%), and current smoker (48%). Patients aged > or = 65 years had a fivefold increased risk for hospitalization. The most commonly reported symptoms were cough (100%), shortness of breath (87%), and fever (74%). Of the 11 hospitalized patients, three required intensive care, and one required mechanical ventilation. One death was reported. Ad14 isolates obtained during the outbreak were identical genetically to those in recent community-acquired outbreaks in the United States which suggests the emergence of a new, and possibly more virulent Ad14 variant. Clinicians should consider Ad14 infection in the differential diagnosis for patients with community-acquired pneumonia, particularly when unexplained clusters of severe respiratory infections are detected
Variable stars in the globular cluster M13
Results of a search for variable stars in the central region of the globular
cluster M13 are presented. Prior to this study, 36 variable and suspected
variable stars were known in this cluster (Osborn 2000; Clement et al. 2001).
Of these stars, five were not observed by us. We find v3, v4, v10, v12, and v13
to be constant in light. Surprisingly, only two out of the ten variable star
candidates of Kadla et al. (1980) appear to be variable. Both are RRc
variables. Additionally, three RR Lyrae stars and one SX Phoenicis variable are
discovered. Three close frequencies are detected for an RRc star v36. It
appears that this variable is another multi-periodic RR Lyrae star pulsating in
non-radial modes. Light curves of the three known BL Herculis stars and all
known RR Lyrae stars are presented. The total number of known RR Lyrae stars in
M13 is now nine. Only one is an RRab star. The mean period of RRc variables
amounts to 0.36 +/- 0.05 d, suggesting that M13 should be included in the group
of Oosterhoff type II globular clusters. Mean V magnitudes and ranges of
variation are derived for seven RR Lyrae and three BL Herculis variables.
Almost all observed bright giants show some degree of variability. In
particular, we confirm the variability of two red giants announced to be
variable by Osborn (2000) and in addition find five new cases.Comment: 10 pages, 9 figures, 5 tables, accepted for publication in AA
Initial results of tests of depth markers as a surface diagnostic for fusion devices
The Accelerator-Based In Situ Materials Surveillance (AIMS) diagnostic was developed to perform in situ ion beam analysis (IBA) on Alcator C-Mod in August 2012 to study divertor surfaces between shots. These results were limited to studying low-Z surface properties, because the Coulomb barrier precludes nuclear reactions between high-Z elements and the ∼1 MeV AIMS deuteron beam. In order to measure the high-Z erosion, a technique using deuteron-induced gamma emission and a low-Z depth marker is being developed. To determine the depth of the marker while eliminating some uncertainty due to beam and detector parameters, the energy dependence of the ratio of two gamma yields produced from the same depth marker will be used to determine the ion beam energy loss in the surface, and thus the thickness of the high-Z surface. This paper presents the results of initial trials of using an implanted depth marker layer with a deuteron beam and the method of ratios. First tests of a lithium depth marker proved unsuccessful due to the production of conflicting gamma peaks, among other issues. However, successful trials with a boron depth marker show that it is possible to measure the depth of the marker layer with the method of gamma yield ratios.United States. Department of Energy. (grant number DE-FG02-94ER54235, cooperative agreement number DEFC02-99ER54512
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