577 research outputs found
Using airborne LiDAR Survey to explore historic-era archaeological landscapes of Montserrat in the eastern Caribbean
This article describes what appears to be the first archaeological application of airborne LiDAR survey to historic-era landscapes in the Caribbean archipelago, on the island of Montserrat. LiDAR is proving invaluable in extending the reach of traditional pedestrian survey into less favorable areas, such as those covered by dense neotropical forest and by ashfall from the past two decades of active eruptions by the SoufriĂšre Hills volcano, and to sites in localities that are inaccessible on account of volcanic dangers. Emphasis is placed on two aspects of the research: first, the importance of ongoing, real-time interaction between the LiDAR analyst and the archaeological team in the field; and second, the advantages of exploiting the full potential of the three-dimensional LiDAR point cloud data for purposes of the visualization of archaeological sites and features
The U.S. market for imported wildlife not listed in the CITES multilateral treaty
Published December 2022The international wildlife trade presents severe conservation and environmental security risks, yet no international regulatory framework exists to monitor the trade of species not listed in the appendices of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). We explored the composition and dynamics of internationally regulated versus nonregulated trade, with a focus on importations of wild-caught terrestrial vertebrates entering the United States from 2009 to 2018. We used 10 years of species-level trade records of the numbers of live, wild-caught animals imported to the United States and data on International Union for the Conservation of Nature (IUCN) estimates of extinction risk to determine whether there were differences in the diversity, abundance, and risk to extinction among imports of CITES-listed versus unlisted species. We found 3.6 times the number of unlisted species in U.S. imports compared with CITESlisted species (1366 vs. 378 species). The CITES-listed species were more likely to face reported conservation threats relative to unlisted species (71.7% vs. 27.5%). However, 376 unlisted species faced conversation threats, 297 species had unknown population trends, and 139 species were without an evaluation by the IUCN. Unlisted species appearing for the first time in records were imported 5.5 times more often relative to CITES-listed species. Unlisted reptiles had the largest rate of entry, averaging 53 unique species appearing in imports for the first time per year. Overall trade quantities were approximately 11 times larger for imports of unlisted species relative to imports of CITES-listed species. Countries that were top exporters of CITES-listed species were mostly different from exporters of unlisted species. Because of the vulnerabilities of unlisted, traded species entering the United States and increasing global demand, we strongly recommend governments adapt their policies to monitor and report on the trade of all wildlife.Freyja Watters, Oliver Stringham, Chris R. Shepherd, Phillip Casse
Formation of black-hole X-ray binaries in globular clusters
Inspired by the recent identification of the first candidate BH-WD X-ray
binaries, where the compact accretors may be stellar-mass black hole candidates
in extragalactic globular clusters, we explore how such binaries could be
formed in a dynamical environment. We provide analyses of the formation rates
via well known formation channels like binary exchange and physical collisions
and propose that the only possibility to form BH-WD binaries is via coupling
these usual formation channels with subsequent hardening and/or triple
formation. Indeed, we find that the most important mechanism to make a BH-WD
X-ray binary from an initially dynamically formed BH-WD binary is triple
induced mass transfer via the Kozai mechanism. Even using the most optimistic
estimates for the formation rates, we cannot match the observationally inferred
production rates if black holes undergo significant evaporation from the
cluster or form a completely detached subcluster of black holes. We estimate
that at least 1% of all formed black holes, or presumably 10% of the black
holes present in the core now, must be involved in interactions with the rest
of the core stellar population.Comment: 10 pages, 2 figures, submitted to Ap
Eight gamma-ray pulsars discovered in blind frequency searches of Fermi LAT data
We report the discovery of eight gamma-ray pulsars in blind frequency
searches using the LAT, onboard the Fermi Gamma-ray Space Telescope. Five of
the eight pulsars are young (tau_c10^36 erg/s), and
located within the Galactic plane (|b|<3 deg). The remaining three are older,
less energetic, and located off the plane. Five pulsars are associated with
sources included in the LAT bright gamma-ray source list, but only one, PSR
J1413-6205, is clearly associated with an EGRET source. PSR J1023-5746 has the
smallest characteristic age (tau_c=4.6 kyr) and is the most energetic
(Edot=1.1E37 erg/s) of all gamma-ray pulsars discovered so far in blind
searches. PSRs J1957+5033 and J2055+25 have the largest characteristic ages
(tau_c~1 Myr) and are the least energetic (Edot~5E33 erg/s) of the
newly-discovered pulsars. We present the timing models, light curves, and
detailed spectral parameters of the new pulsars. We used recent XMM
observations to identify the counterpart of PSR J2055+25 as XMMU
J205549.4+253959. In addition, publicly available archival Chandra X-ray data
allowed us to identify the likely counterpart of PSR J1023-5746 as a faint,
highly absorbed source, CXOU J102302.8-574606. The large X-ray absorption
indicates that this could be among the most distant gamma-ray pulsars detected
so far. PSR J1023-5746 is positionally coincident with the TeV source HESS
J1023-575, located near the young stellar cluster Westerlund 2, while PSR
J1954+2836 is coincident with a 4.3 sigma excess reported by Milagro at a
median energy of 35 TeV. Deep radio follow-up observations of the eight pulsars
resulted in no detections of pulsations and upper limits comparable to the
faintest known radio pulsars, indicating that these can be included among the
growing population of radio-quiet pulsars in our Galaxy being uncovered by the
LAT, and currently numbering more than 20.Comment: Submitted to Ap
Emergency and critical care services in Tanzania: a survey of ten hospitals.
While there is a need for good quality care for patients with serious reversible disease in all countries in the world, Emergency and Critical Care tends to be one of the weakest parts of health systems in low-income countries. We assessed the structure and availability of resources for Emergency and Critical Care in Tanzania in order to identify the priorities for improving care in this neglected specialty. Ten hospitals in four regions of Tanzania were assessed using a structured data collection tool. Quality was evaluated with standards developed from the literature and expert opinion. Important deficits were identified in infrastructure, routines and training. Only 30% of the hospitals had an emergency room for adult and paediatric patients. None of the seven district and regional hospitals had a triage area or intensive care unit for adults. Only 40% of the hospitals had formal systems for adult triage and in less than one third were critically ill patients seen by clinicians more than once daily. In 80% of the hospitals there were no staff trained in adult triage or critical care. In contrast, a majority of equipment and drugs necessary for emergency and critical care were available in the hospitals (median 90% and 100% respectively. The referral/private hospitals tended to have a greater overall availability of resources (median 89.7%) than district/regional hospitals (median 70.6). Many of the structures necessary for Emergency and Critical Care are lacking in hospitals in Tanzania. Particular weaknesses are infrastructure, routines and training, whereas the availability of drugs and equipment is generally good. Policies to improve hospital systems for the care of emergency and critically ill patients should be prioritised
An introduction to Graph Data Management
A graph database is a database where the data structures for the schema
and/or instances are modeled as a (labeled)(directed) graph or generalizations
of it, and where querying is expressed by graph-oriented operations and type
constructors. In this article we present the basic notions of graph databases,
give an historical overview of its main development, and study the main current
systems that implement them
An unusual cause of granulomatous disease
BACKGROUND: Chronic granulomatous disease (CGD) is an inherited disorder of phagocytic cells caused by an inability to generate active microbicidal oxygen species required kill certain types of fungi and bacteria. This leads to recurrent life-threatening bacterial and fungal infections with tissue granuloma formation. CASE PRESENTATION: We describe a case of X-linked Chronic granulomatous disease (CGD) diagnosed in an 18-year-old male. He initially presented with granulomatous disease mimicking sarcoidosis and was treated with corticosteroids. He subsequently developed Burkholderia cepacia complex pneumonia and further investigation confirmed a diagnosis of CGD. CONCLUSION: Milder phenotypes of CGD are now being recognised. CGD should be considered in patients of any age with granulomatous diseases, especially if there is a history of recurrent or atypical infection
PSR J1907+0602: A Radio-Faint Gamma-Ray Pulsar Powering a Bright TeV Pulsar Wind Nebula
We present multiwavelength studies of the 106.6 ms gamma-ray pulsar PSR
J1907+06 near the TeV source MGRO J1908+06. Timing observations with Fermi
result in a precise position determination for the pulsar of R.A. =
19h07m547(2), decl. = +06:02:16(2) placing the pulsar firmly within the TeV
source extent, suggesting the TeV source is the pulsar wind nebula of PSR
J1907+0602. Pulsed gamma-ray emission is clearly visible at energies from 100
MeV to above 10 GeV. The phase-averaged power-law index in the energy range E >
0.1 GeV is = 1.76 \pm 0.05 with an exponential cutoff energy E_{c} = 3.6 \pm
0.5 GeV. We present the energy-dependent gamma-ray pulsed light curve as well
as limits on off-pulse emission associated with the TeV source. We also report
the detection of very faint (flux density of ~3.4 microJy) radio pulsations
with the Arecibo telescope at 1.5 GHz having a dispersion measure DM = 82.1 \pm
1.1 cm^{-3}pc. This indicates a distance of 3.2 \pm 0.6 kpc and a
pseudo-luminosity of L_{1400} ~ 0.035 mJy kpc^2. A Chandra ACIS observation
revealed an absorbed, possibly extended, compact <(4 arcsec) X-ray source with
significant non-thermal emission at R.A. = 19h07m54.76, decl. = +06:02:14.6
with a flux of 2.3^{+0.6}_{-1.4} X 10^{-14} erg cm^{-2} s^{-1}. From archival
ASCA observations, we place upper limits on any arcminute scale 2--10 keV X-ray
emission of ~ 1 X 10^{-13} erg cm^{-2} s^{-1}. The implied distance to the
pulsar is compatible with that of the supernova remnant G40.5-0.5, located on
the far side of the TeV nebula from PSR J1907+0602, and the S74 molecular cloud
on the nearer side which we discuss as potential birth sites
Fermi LAT observations of the Geminga pulsar
We report on the \textit{Fermi}-LAT observations of the Geminga pulsar, the
second brightest non-variable GeV source in the -ray sky and the first
example of a radio-quiet -ray pulsar. The observations cover one year,
from the launch of the satellite through 2009 June 15. A data sample of
over 60,000 photons enabled us to build a timing solution based solely on
rays. Timing analysis shows two prominent peaks, separated by = 0.497 0.004 in phase, which narrow with increasing energy. Pulsed
rays are observed beyond 18 GeV, precluding emission below 2.7 stellar
radii because of magnetic absorption. The phase-averaged spectrum was fitted
with a power law with exponential cut-off of spectral index = (1.30
0.01 0.04), cut-off energy = (2.46 0.04 0.17)
GeV and an integral photon flux above 0.1 GeV of (4.14 0.02 0.32)
10 cm s. The first uncertainties are statistical
and the second are systematic. The phase-resolved spectroscopy shows a clear
evolution of the spectral parameters, with the spectral index reaching a
minimum value just before the leading peak and the cut-off energy having maxima
around the peaks. Phase-resolved spectroscopy reveals that pulsar emission is
present at all rotational phases. The spectral shape, broad pulse profile, and
maximum photon energy favor the outer magnetospheric emission scenarios.Comment: 32 pages, 12 figures, 3 tables. Accepted for publication in The
Astrophysical Journal. Corresponding authors: Denis Dumora
([email protected]), Fabio Gargano ([email protected]),
Massimiliano Razzano ([email protected]
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