6,340 research outputs found
KMOS LENsing Survey (KLENS) : morpho-kinematic analysis of star-forming galaxies at
We present results from the KMOS lensing survey-KLENS which is exploiting
gravitational lensing to study the kinematics of 24 star forming galaxies at
with a median mass of and median
star formation rate (SFR) of . We find that 25% of
these low-mass/low-SFR galaxies are rotation dominated, while the majority of
our sample shows no velocity gradient. When combining our data with other
surveys, we find that the fraction of rotation dominated galaxies increases
with the stellar mass, and decreases for galaxies with a positive offset from
the main sequence. We also investigate the evolution of the intrinsic velocity
dispersion, , as a function of the redshift, , and stellar mass,
, assuming galaxies in quasi-equilibrium (Toomre Q parameter equal
to 1). From the relation, we find that the redshift evolution of
the velocity dispersion is mostly expected for massive galaxies (). We derive a relation, using
the Tully-Fisher relation, which highlights that a different evolution of the
velocity dispersion is expected depending on the stellar mass, with lower
velocity dispersions for lower masses, and an increase for higher masses,
stronger at higher redshift. The observed velocity dispersions from this work
and from comparison samples spanning appear to follow this relation,
except at higher redshift (), where we observe higher velocity dispersions
for low masses () and lower velocity
dispersions for high masses () than
expected. This discrepancy could, for instance, suggest that galaxies at
high- do not satisfy the stability criterion, or that the adopted
parametrisation of the specific star formation rate and molecular properties
fail at high redshift.Comment: Accepted for publication in A&A, 21 pages, 10 figure
Vector magnetic hysteresis of hard superconductors
Critical state problems which incorporate more than one component for the
magnetization vector of hard superconductors are investigated. The theory is
based on the minimization of a cost functional
which weighs the changes of the magnetic field vector within the sample. We
show that Bean's simplest prescription of choosing the correct sign for the
critical current density in one dimensional problems is just a particular
case of finding the components of the vector . is
determined by minimizing under the constraint , with a bounded set. Upon the selection of
different sets we discuss existing crossed field measurements and
predict new observable features. It is shown that a complex behavior in the
magnetization curves may be controlled by a single external parameter, i.e.:
the maximum value of the applied magnetic field .Comment: 10 pages, 9 figures, accepted in Phys. Rev.
High spatial resolution optical imaging of the multiple T Tauri system LkH{\alpha} 262/LkH{\alpha} 263
We report high spatial resolution i' band imaging of the multiple T Tauri
system LkH 262/LkH 263 obtained during the first commissioning
period of the Adaptive Optics Lucky Imager (AOLI) at the 4.2 m William Herschel
Telescope, using its Lucky Imaging mode. AOLI images have provided photometry
for each of the two components LkH 263 A and B (0.41 arcsec separation)
and marginal evidence for an unresolved binary or a disc in LkH 262.
The AOLI data combined with previously available and newly obtained optical and
infrared imaging show that the three components of LkH 263 are
co-moving, that there is orbital motion in the AB pair, and, remarkably, that
LkH 262-263 is a common proper motion system with less than 1 mas/yr
relative motion. We argue that this is a likely five-component gravitationally
bounded system. According to BT-settl models the mass of each of the five
components is close to 0.4 M and the age is in the range 1-2 Myr. The
presence of discs in some of the components offers an interesting opportunity
to investigate the formation and evolution of discs in the early stages of
multiple very low-mass systems. In particular, we provide tentative evidence
that the disc in 263C could be coplanar with the orbit of 263AB.Comment: 11 pages, 7 figures, Accepted 2016 May
Use of serology in a systematic screening programme for strongyloidiasis in an immigrant population
Objectives: The aim of this cross-sectional study was to describe the results of a systematic serological
screening programme for strongyloidiasis.
Methods: Aprospective serological screeningprogramme for strongyloidiasis wasperformedbetween2009
and2014 for allimmigrantpatients attending theTropicalMedicineUnit. Three formalin-etherconcentrated
stool samples and an ELISA for anti-Strongyloides stercoralis antibodies were used as screening tools.
Results: Of 659 patients screened, 79 (12%) were positive for S. stercoralis regardless of the diagnostic
method used. The prevalence of infection was 42.9% in East African patients, 16.3% in Central African
patients,10.9% in those fromSouthAmerica, and 10% in the case ofWestAfrica. Univariate analysis showed
thatinfection by S. stercoralis was significantly more frequentinpatients from CentralAfrica (p = 0.026; OR
1.72, 95% CI 1.03–2.85) and East Africa (p<0.001; OR 5.88, 95% CI 1.75–19.32). Taking West Africa as the
reference (as the area of lowest prevalence among the positive prevalence areas), the statistical analysis
showed that the risk of infection was higher in East Africa (p = 0.001; OR 6.750, 95% CI 2.127–21.423) and
Central Africa (p = 0.065; OR 1.747, 95% CI 0.965–3.163).
Conclusions: Due to the potential complications of strongyloidiasis infection, we recommend that
immigrantpatients fromdevelopingcountriesbe routinelyscreenedfor S. stercoralis, especiallythose from
East Africa. A serological test is a highly appropriate screening tool
Negative Pressures in QED Vacuum in an External Magnetic Field
Our aim is to study the electron-positron vacuum pressures in presence of a
strong magnetic field . To that end, we obtain a general energy-momentum
tensor, depending on external parameters, which in the zero temperature and
zero density limit leads to vacuum expressions which are
approximation-independent. Anisotropic pressures arise, and in the tree
approximation of the magnetic field case, the pressure along is positive,
whereas perpendicular to it is negative. Due to the common axial symmetry,
the formal analogy with the Casimir effect is discussed, for which in addition
to the usual negative pressure perpendicular to the plates, there is a positive
pressure along the plates. The formal correspondence between the Casimir and
black body energy-momentum tensors is analyzed. The fermion hot vacuum behavior
in a magnetic field is also briefly discussed
Obtención de jarabes glucosados por hidrólisis enzimática empleando almidón de sorgo CIAPR-132
La presente investigación está encaminada al estudio de la posible sustitución del maíz por el sorgo en la producción de jarabes glucosados para la industria alimenticia, considerando la evaluación de las potencialidades de dicho cereal. En este sentido se realizó un diseño experimental compuesto del tipo 2k, utilizando el Software Statgraphics Centurion XV en elprocesamiento de los resultados del proceso desarrolladoen el laboratorio. Para ello se analizó la influenciade las variables independientes: concentración deenzima alfa amilasa (X1) en los niveles de 0,06 y 0,16%p/p, la concentración de enzima amiloglucosidasa(AMG) (X2) en los niveles de 0,18 y 0,375 %p/p ytiempo de sacarificación (X3) de 24 y 48 horas sobrelas variables respuestas °Brix y Azúcares ReductoresTotales (ART); además se determinó el rendimiento de cada experimento, obteniéndose los mejores resultados para la mayor concentración de enzima alfaamilasa, concentración de enzima AMG y tiempo de sacarificación en los menores valores. Los mejores resultados se obtuvieron para el Brix de 52,22 y ARTde 68,76%
An instrumental puzzle: the modular integration of AOLI
The Adaptive Optics Lucky Imager, AOLI, is an instrument developed to deliver
the highest spatial resolution ever obtained in the visible, 20 mas, from
ground-based telescopes. In AOLI a new philosophy of instrumental prototyping
has been applied, based on the modularization of the subsystems. This modular
concept offers maximum flexibility regarding the instrument, telescope or the
addition of future developments.Comment: 10 pages, 8 figures, Proc. SPIE 9908, Ground-based and Airborne
Instrumentation for Astronomy VI, 99082Z (August 9, 2016
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