758 research outputs found
Signature of the presence of a third body orbiting around XB 1916-053
The ultra-compact dipping source \object{XB 1916-053} has an orbital period
of close to 50 min and a companion star with a very low mass (less than 0.1
M). The orbital period derivative of the source was estimated to be
s/s through analysing the delays associated with the
dip arrival times obtained from observations spanning 25 years, from 1978 to
2002. The known orbital period derivative is extremely large and can be
explained by invoking an extreme, non-conservative mass transfer rate that is
not easily justifiable. We extended the analysed data from 1978 to 2014, by
spanning 37 years, to verify whether a larger sample of data can be fitted with
a quadratic term or a different scenario has to be considered. We obtained 27
delays associated with the dip arrival times from data covering 37 years and
used different models to fit the time delays with respect to a constant period
model.We find that the quadratic form alone does not fit the data. The data are
well fitted using a sinusoidal term plus a quadratic function or,
alternatively, with a series of sinusoidal terms that can be associated with a
modulation of the dip arrival times due to the presence of a third body that
has an elliptical orbit. We infer that for a conservative mass transfer
scenario the modulation of the delays can be explained by invoking the presence
of a third body with mass between 0.10-0.14 M, orbital period around
the X-ray binary system of close to 51 yr and an eccentricity of . In a non-conservative mass transfer scenario we estimate that the
fraction of matter yielded by the degenerate companion star and accreted onto
the neutron star is , the neutron star mass is
M, and the companion star mass is 0.028 M. (Abridged)Comment: 13 pages, 9 figures. Accepted for publication in A&
PI3K signalling in leptin receptor cells: Role in growth and reproduction
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149245/1/jne12685_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149245/2/jne12685.pd
A possible cyclotron resonance scattering feature near 0.7 keV in X1822-371
We analyse all available X-ray observations of X1822-371 made with
XMM-Newton, Chandra, Suzaku and INTEGRAL satellites. The observations were not
simultaneous. The Suzaku and INTEGRAL broad band energy coverage allows us to
constrain the spectral shape of the continuum emission well. We use the model
already proposed for this source, consisting of a Comptonised component
absorbed by interstellar matter and partially absorbed by local neutral matter,
and we added a Gaussian feature in absorption at keV. This addition
significantly improves the fit and flattens the residuals between 0.6 and 0.8
keV. We interpret the Gaussian feature in absorption as a cyclotron resonant
scattering feature (CRSF) produced close to the neutron star surface and derive
the magnetic field strength at the surface of the neutron star, G for a radius of 10 km. We derive the pulse period in the
EPIC-pn data to be 0.5928850(6) s and estimate that the spin period derivative
of X1822-371 is s/s using all available
pulse period measurements. Assuming that the intrinsic luminosity of
X1822-371is at the Eddington limit and using the values of spin period and spin
period derivative of the source, we constrain the neutron star and companion
star masses. We find the neutron star and the companion star masses to be M and M, respectively, for a
neutron star radius of 10 km.In a self-consistent scenario in which X1822-371
is spinning-up and accretes at the Eddington limit, we estimate that the
magnetic field of the neutron star is G for a
neutron star radius of 10 km. If our interpretation is correct, the Gaussian
absorption feature near 0.7 keV is the very first detection of a CRSF below 1
keV in a LMXB. (abridged)Comment: 14 pages, 12 figures, accepted for publication in A&
Membrane Bioreactor and Promising Application for Textile Industry in Vietnam
Abstract A pilot-scale membrane bioreactor (MBR) was developed in order to run two membrane modules in parallel for the treatment of model textile wastewater (MTDW). Two independently operated commercially available ultrafiltration membrane modules called UP150 from Microdyn-Nadir where tested in the same activated sludge tank over a period of 70 days for their removal efficiency of the MTDW. In general the results of both membrane modules are in very good agreement. The water permeability ranged between 20 – 50 L/(m 2 .h.bar). Typically, the chemical oxygen demand (COD) removal efficiency indicated good biodegradation performance above 95%. The nitrification rate depended on the food to microorganism (F/M) ratio i.e. below 0.2 kg COD/(kg MLSS.d) the system showed complete nitrification. However, the color rejection for the model dyes was only around 20% to 60% what can be attributed to the low biodegradability of these chemicals. The next step is to run the MBR with novel nanostructured membranes in parallel with the commercially available membrane to compare their performances. This study contributes to sustainable development in the textile industry by improving water quality of treated textile wastewater what helps to reduce fresh water consumption and pollutant discharge
Propiedades de paneles geopoliméricos basados en ceniza volante y metacaolín bajo ensayos de resistencia al fuego
This paper presents the results of a study about the effect of fire on geopolymer paste composed of fly ashes, metakaolin and sodium silicate. 2 cm thick, 28 cm high and 18 cm wide panels were filled with the paste obtained. After 28 days of curing at 20 °C and 45% of relative humidity, different tests were carried out in the geopolymers: physico-chemical (density, water absorption, porosity), mechanical (flexural and compressive strength), fire resistance and environmental (leaching and radioactivity). The panels manufactured have been compared with other commercial panels in order to determine the recycling possibilities of fly ashes in manufacturing new fire-insulating geopolymers. The panels obtained can be utilized for the production of interior wall materials, with a good physical, mechanical, fire resistant properties without any environmental problem.Este documento presenta los resultados de un estudio sobre el efecto del fuego sobre pastas de geopolímeros compuestas de cenizas volantes, metacaolín y silicato sódico. Con la pasta obtenida se han rellenado paneles de dimensiones 2 cm de espesor, 28 cm de altura y 18 cm de ancho. Tras 28 días de curado a 20 °C y un 45% de humedad relativa, diferentes ensayos fueron realizados en los geopolímeros obtenidos: fisicoquímicos (densidad, absorción de agua, porosidad), mecánicos (resistencia a compresión y a flexión), de resistencia al fuego y medioambientales (lixiviación y radioactividad). Los paneles fabricados han sido comparados con paneles comerciales para determinar las posibilidades de reciclaje de las cenizas volantes para la fabricación de nuevos productos geopoliméricos con propiedades aislantes al fuego. Los paneles obtenidos pueden ser utilizados para la producción de paredes interiores, con buenas propiedades físicas, mecánicas y de resistencia al fuego sin ningún problema medioambiental
GRO J1744-28: an intermediate B-field pulsar in a low mass X-ray binary
The bursting pulsar, GRO J1744-28, went again in outburst after 18
years of quiescence in mid-January 2014. We studied the broad-band, persistent,
X-ray spectrum using X-ray data from a XMM-Newton observation, performed almost
at the peak of the outburst, and from a close INTEGRAL observation, performed 3
days later, thus covering the 1.3-70.0 keV band. The spectrum shows a complex
continuum shape that cannot be modelled with standard high-mass X-ray pulsar
models, nor by two-components models. We observe broadband and peaked residuals
from 4 to 15 keV, and we propose a self-consistent interpretation of these
residuals, assuming they are produced by cyclotron absorption features and by a
moderately smeared, highly ionized, reflection component. We identify the
cyclotron fundamental at 4.7 keV, with hints for two possible harmonics
at 10.4 keV and 15.8 keV. The position of the cyclotron fundamental allows an
estimate for the pulsar magnetic field of (5.27 0.06) 10
G, if the feature is produced at its surface. From the dynamical and
relativistic smearing of the disk reflected component, we obtain a lower limit
estimate for the truncated accretion disk inner radius, ( 100 R),
and for the inclination angle (18-48). We also detect the
presence of a softer thermal component, that we associate with the emission
from an accretion disk truncated at a distance from the pulsar of 50-115 R.
From these estimates, we derive the magneto-spheric radius for disk accretion
to be 0.2 times the classical Alfv\'en radius for radial accretion.Comment: Accepted for publication in MNRA
Estudio de la flora muscinal del hayedo de Montejo de la Sierra (provincia de Madrid)
Sin resume
Factores asociados con casos esporádicos de salmonelosis en niños de 1 a 7 años. Estudio de casos y controles
ObjetivoEl conocimiento de los factores de riesgo de la salmonelosis proviene en gran parte de los estudios de brotes de toxiinfección alimentaria, pero es menos conocida la epidemiología de los casos esporádicos. Sin embargo, muchos de los casos atendidos en el sistema sanitario son esporádicos, especialmente niños. Este estudio pretende aportar conocimientos sobre algunos de los determinantes de esos casos.MétodosEstudio de casos y controles (113 niños) de hospital y atención primaria. Casos incidentes de diarrea en niños de 1 a 7 años ocurridos entre diciembre de 1994 y diciembre de 1995 y con coprocultivo positivo a Salmonella. Controles de igual procedencia pero con coprocultivo positivo a Campylobacter o virus. Se estudian factores alimentarios, del entorno de los casos y antecedentes próximos. Se calculan las Odds Ratio (OR) ajustadas por los factores relacionados, edad, sexo y época del año mediante regresión logística.ResultadosEl consumo de carne picada del comercio durante los tres días previos a la diarrea, OR=4,07 (1,20–13,8) y OR=5,63 (1,34–23,6) para cada grupo control, la posesión de animales domésticos, OR=8,27 (1,96–34,9) y la toma de antibióticos en la semana previa a la diarrea, OR=4,75 (0,84–27,0) estuvieron epidemiológicamente asociados con la enfermedad.ConclusionesLa epidemiología de los casos esporádicos de salmonelosis en niños de esta edad parece diferir de la de los típicamente asociados a brotes de infección alimentaria, y es más compleja. El consumo de carne picada en el comercio, la toma previa de antibióticos y la posesión de animales domésticos pueden suponer un riesgo para la salmonelosis infantil y habrían de ser considerados en futuros estudios sobre esta materia.BackgroundKnowledge about salmonellosis risk factors mainly comes from foodborne outbreaks, and we know little about sporadic cases epidemiology. However most of the cases are sporadic, specially children. This study aims to find out some of determinants of these cases.MethodsA case-control study with incident cases and controls from the same base population (laboratory diagnosed cases). Cases were children 1–7 years old, afected by diarrohea with culture stools positive to Salmonella between decembre 1994 and decembre 1995. Controls from the same source, but positive culture to Campylobacter or viruses. We study food and other environmental risk factors. Odds ratio (OR) are calculated adjusted for age, sex, and year period (cool and cold) by logistic regression.ResultsEating minced meat during three days before symptoms, OR 4,07 (1.20–13.8) and OR 5.63 (1.34–23.6); pets, OR 8.27 (1.96–34.9), and antibiotics the week before symptoms, OR 4.75 (0.84–27.0) were epidemiologicaly associated with salmonelosis diarrohea.ConclusionsEpidemiology of salmonelosis sporadic cases in children seems diferent to the foodborne associated cases and is more complex. Minced meat tree days before symptoms, antibiotics the week before symptoms, and pets could be a risk for this kind of cases. Future studies must also take account of this factors
Study of the physical properties of soils through interpretation of aerial photographs
Final technical reportThe purpose of the research work proposed is the study of the physical
properties of the soils by means of the interpretation of aerial photographs.
This study is to be carried out in two years and thus it is not possible to
give definite conclusions at the end of the first year, although the results
we have obtained are highly satisfactory. In our opinion and after the experience
of the first year, the working problem of the study of the physical
properties of the soils through aerial photographs, can be examined from two
different aspects. The first of them could be called the "deductive" method
and consists in acquiring knowledge of the physical properties of the soils
by means of sucoessive interpretations of aerial photographs; through photointerpretation
we study the physical Geography of an area, its hydrographic
net, natural vegetation and .man-introduced cultivations, the forms of erosion
end the nature of the geological material, All these interpretations, together
with the clitmate, allow to "deduce" the nature of the soils of that area, as
all the pedological processes which the different geological materials have
undergone can be know perfectly well, which also shows the intensity of physical
and chemical desintegration of the materials that form the starting
point of soil formation.The research reported in this document has been made possible through the support and sponsorship of the U.S. Department of the Army through its European Research Office.Contract No. DA-91-591-EUC-2652 1st. April 1963 to 31th March
1964.N
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