6,175 research outputs found
The X-ray Properties of M101 ULX-1 = CXOKM101 J140332.74+542102
We report our analysis of X-ray data on M101 ULX-1, concentrating on high
state Chandra and XMM-Newton observations. We find that the high state of M101
ULX-1 may have a preferred recurrence timescale. If so, the underlying clock
may have periods around 160 or 190 days, or possibly around 45 days. Its
short-term variations resemble those of X-ray binaries at high accretion rate.
If this analogy is correct, we infer that the accretor is a 20-40 Msun object.
This is consistent with our spectral analysis of the high state spectra of M101
ULX-1, from which we find no evidence for an extreme (> 10^40 ergs/s)
luminosity. We present our interpretation in the framework of a high mass X-ray
binary system consisting of a B supergiant mass donor and a large stellar-mass
black hole.Comment: 23 pages, 7 figures, accepted for publication in the Astrophysical
Journa
Mosquito larvicidal properties of Orthosiphon thymiflorus (Roth) Sleesen. (Family: Labiatae) against mosquito vectors, Anopheles stephensi, Culex quinquefasciatus and Aedes aegypti (Diptera: Culicidae)
AbstractObjectiveTo determine the mosquito larvicidal activities of hexane, chloroform, ethyl acetate, acetone and methanol leaf extract of Orthosiphon thymiflorus (O. thymiflorus) against Anopheles stephensi (An. stephensi), Culex quinquefasciatus (Cx. quinquefasciatus) and Aedes aegypti (Ae. aegypti).MethodsThe larvicidal activity was assayed against three mosquito species at various concentrations ranging from (50-450 ppm) under the laboratory conditions. The LC50 and LC90 value of the O. thymiflorus leaf extract was determined by Probit analysis.ResultsThe LC50 values of hexane, chloroform, ethyl acetate, acetone and methanol extract of O. thymiflorus third instar larvae of An. stephensi were LC50= 201.39, 178.76, 158.06, 139.22 and 118.74 ppm; Cx. quinquefasciatus were LC50=228.13, 209.72, 183.35, 163.55 and 149.96 ppm and Ae. aegypti were LC50=215.65, 197.91, 175.05, 154.80 and 137.26 ppm, respectively. Maximum larvicidal activity was observed in the methanolic extract followed by acetone, ethyl acetate chloroform and hexane extract. The larval mortality was observed after 24 h exposure. No mortality was observed in control.ConclusionsThe present results suggest that the effective plant crude extracts have potential to be used as an ideal eco-friendly approach for the control of mosquito vectors. This study provides the first report on the larvicidal activity of this plant crude solvent extract of against An. stephensi, Cx. quinquefasciatus and Ae. aegypti mosquitoes
Objects that Sound
In this paper our objectives are, first, networks that can embed audio and
visual inputs into a common space that is suitable for cross-modal retrieval;
and second, a network that can localize the object that sounds in an image,
given the audio signal. We achieve both these objectives by training from
unlabelled video using only audio-visual correspondence (AVC) as the objective
function. This is a form of cross-modal self-supervision from video.
To this end, we design new network architectures that can be trained for
cross-modal retrieval and localizing the sound source in an image, by using the
AVC task. We make the following contributions: (i) show that audio and visual
embeddings can be learnt that enable both within-mode (e.g. audio-to-audio) and
between-mode retrieval; (ii) explore various architectures for the AVC task,
including those for the visual stream that ingest a single image, or multiple
images, or a single image and multi-frame optical flow; (iii) show that the
semantic object that sounds within an image can be localized (using only the
sound, no motion or flow information); and (iv) give a cautionary tale on how
to avoid undesirable shortcuts in the data preparation.Comment: Appears in: European Conference on Computer Vision (ECCV) 201
Submerged in the mainstream? A case study of an immigrant learner in a New Zealand primary classroom
Immigrant children from diverse language backgrounds face not only linguistic challenges when enrolled in mainstream English-medium classrooms, but also difficulties adjusting to an unfamiliar learning community. The culture of primary school classrooms in New Zealand typically reflects conventions across three dimensions: interactional, instructional task performance and cognitive-academic development. All three dimensions are underpinned by the culturally specific discourse conventions involved in language socialisation. New learners may be helped by classmates or their teacher to understand and successfully use these conventions, but left on their own they may sink rather than swim. This is a case study of one Taiwanese 11-year old boy, 'John', who entered a New Zealand primary classroom midway through the school year. John's basic conversational ability was sound, but he did not possess the interactive classroom skills needed to operate in the new culture of learning. Selected from a wider study of the classroom, transcript data from audio-recorded excerpts of John's interactions over several months with his teacher and classmates are interpreted from perspectives derived from sociocultural and language socialisation theories. The article concludes with a brief consideration of the extent to which John constructed, or was constrained from constructing meaningful learning experiences, and suggestions for further research and reflection
RX J0042.3+4115: a stellar mass black hole binary identified in M31
Four XMM-Newton X-ray observations of the central region of the Andromeda
Galaxy (M31) have revealed an X-ray source that varies in luminosity over
\~1--3, 10^{38} erg s^{-1} between observations and also displays significant
variability over time-scales of a few hundred seconds. The power density
spectra of lightcurves obtained in the 0.3--10 keV energy band from the three
EPIC instruments on board XMM-Newton are typical of disc-accreting X-ray
binaries at low accretion rates, observed in neutron star binaries only at much
lower luminosities (~10^{36} erg s^{-1}). However X-ray binaries with massive
black hole primaries have exhibited such power spectra for luminosities
>10^{38} erg s^{-1}. We discuss alternative possibilities where RX J0042.3+4115
may be a background AGN or foreground object in the field of view, but conclude
that it is located within M31 and hence use the observed power spectra and
X-ray luminosities to identify the primary as a black hole candidate.Comment: 7 pages, 4 figures, A&A accepte
Thermal spin transport and spin-orbit interaction in ferromagnetic/non-magnetic metals
In this article we extend the currently established diffusion theory of
spin-dependent electrical conduction by including spin-dependent
thermoelectricity and thermal transport. Using this theory, we propose new
experiments aimed at demonstrating novel effects such as the spin-Peltier
effect, the reciprocal of the recently demonstrated thermally driven spin
injection, as well as the magnetic heat valve. We use finite-element methods to
model specific devices in literature to demonstrate our theory. Spin-orbit
effects such as anomalous-Hall, -Nernst, anisotropic magnetoresistance and
spin-Hall are also included in this model
Transport properties of the heavy fermion superconductor PrOsSb
We have measured the electrical resistivity, thermoelectric power, Hall
coefficient, and magnetoresistance (MR) on single crystals of
PrOsSb, LaOsSb and NdOsSb. All the
transport properties in PrOsSb are similar to those in
LaOsSb and NdOsSb at high temperatures, indicating
the localized character of 4-electrons. The transverse MR both in
LaOsSb and PrOsSb tends to saturate for wide field
directions, indicating these compounds to be uncompensated metals with no open
orbit. We have determined the phase diagram of the field induced ordered phase
by the MR measurement for all the principle field directions, which indicates
an unambiguous evidence for the singlet crystalline electric
field ground state.Comment: 7 pages, 10 figures, to appear in Physical Review
Could psoralen plus ultraviolet A1 (“PUVA1”) work? Depth penetration achieved by phototherapy lamps
Funding: PhD Studentship UK EPRSC EP/N509759/1.Psoralen and ultraviolet A (PUVA) is useful in treating various hand and foot skin diseases.1 Most cases of psoriasis respond well to phototherapy or PUVA. However, for some diseases, such as palmoplantar pustular psoriasis, PUVA is not always sufficient to produce therapeutic effect. If PUVA fails, it is sometimes necessary to progress to other treatments such as Grenz ray therapy (where available),2 systemic retinoid or systemic immunosuppression. Could “PUVA1” (psoralen combined with ultraviolet A1 long wavelength ultraviolet A [UVA]) work in cases where conventional PUVA (psoralen plus broadband UVA) has been inadequate?PostprintPeer reviewe
Modeling the iron oxides and oxyhydroxides for the prediction of environmentally sensitive phase transformations
Iron oxides and oxyhydroxides are challenging to model computationally as
competing phases may differ in formation energies by only several kJ/mol, they
undergo magnetization transitions with temperature, their structures may
contain partially occupied sites or long-range ordering of vacancies, and some
loose structures require proper description of weak interactions such as
hydrogen bonding and dispersive forces. If structures and transformations are
to be reliably predicted under different chemical conditions, each of these
challenges must be overcome simultaneously, while preserving a high level of
numerical accuracy and physical sophistication. Here we present comparative
studies of structure, magnetization, and elasticity properties of iron oxides
and oxyhydroxides using density functional theory calculations with plane-wave
and locally-confined-atomic-orbital basis sets, which are implemented in VASP
and SIESTA packages, respectively. We have selected hematite, maghemite,
goethite, lepidocrocite, and magnetite as model systems from a total of 13
known iron oxides and oxyhydroxides; and use same convergence criteria and
almost equivalent settings in order to make consistent comparisons. Our results
show both basis sets can reproduce the energetic stability and magnetic
ordering, and are in agreement with experimental observations. There are
advantages to choosing one basis set over the other, depending on the intended
focus. In our case, we find the method using PW basis set most appropriate, and
combine our results to construct the first phase diagram of iron oxides and
oxyhydroxides in the space of competing chemical potentials, generated entirely
from first principlesComment: 46 pages - Accepted for publication in PRB (19 journal pages),
January 201
The challenges of optimising glycaemic control in children with type 1 diabetes: a qualitative study of parents’ experiences and views
Aims
To explore the difficulties parents encounter in trying to achieve clinically recommended blood glucose levels and how they could be better supported to optimize their child's glycaemic control.
Methods
In-depth interviews were conducted with 54 parents of children with Type 1 diabetes (≤ 12 years). Data were analysed thematically.
Results
Parents described being reluctant and finding it difficult to keep their child's blood glucose levels consistently within clinically recommended ranges. As well as worrying about their child's ability to detect/report hypoglycaemia, parents highlighted a multitude of factors that had an impact on their child's blood glucose levels and over which they could exercise little control. These included: leaving their child with other caregivers who could not be trusted to detect hypoglycaemia; difficulties remotely monitoring and regulating their child's food consumption and activity; and physical and social changes accompanying childhood development. Most parents used two sets of blood glucose targets, with clinically recommended targets employed when their child was in their immediate care and higher targets when in the care of others. Parents described health professionals as lacking understanding of the difficulties they encountered keeping blood glucose within target ranges and needing more empathetic, tailored and realistic advice.
Conclusion
It is not parents' fear of hypoglycaemia in isolation that leads to decisions to raise their child's blood glucose but, rather, parental fear in conjunction with other factors and considerations. Hence, to improve diabetes management in children, these factors may need to be addressed; for instance, by training others in diabetes management and using new technologies. Changes to consultations are also recommended
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