1,498 research outputs found
A Tiltable Single-Shot Miniature Dilution Refrigerator for Astrophysical Applications
We present a 3He / 4He dilution refrigerator designed for cooling
astronomical mm-wave telescope receivers to around 100 mK. Used in combination
with a Gifford-McMahon closed-cycle refrigerator, 4He and 3He sorption-pumped
refrigerators, our cryogen-free system is capable of achieving 2 microW cooling
power at 87 mK. A receiver attached directly to the telescope optics is
required to rotate with respect to the downward direction. This scenario, of
variable tilt, has proved difficult for typical dilution refrigerators, but our
design has a geometry chosen to allow tilt to 45 degrees and beyond.Comment: 7 pages, 11 figures. Accepted by Cryogenic
COBE Observations of the Microwave Counterparts of Gamma Ray Bursts
We have used the data from the COBE satellite to search for delayed microwave
emission (31 - 90 GHz) from Gamma Ray Bursts (GRBs). The large beam
of COBE is well matched to the large positional uncertainties in the GRB
locations, although it also means that fluxes from (point source) GRB objects
will be diluted. In view of this we are doing a statistical search of the GRBs
which occurred during the currently released COBE DMR data (years 1990 and
1991), which overlap GRBs recorded by GRO. Here we concentrate on
just the top 10 GRBs (in peak counts/second). We obtain the limits on the
emission by comparing the COBE fluxes before and after the GRB at the GRB
location. Since it is thought that the microwave emission should lag the GRB
event, we have searched the GRB position for emission in the few months
following the GRB occurrence.Comment: 5 pages, LaTE
COMPASS: a 2.6m telescope for CMBR polarization studies
COMPASS (COsmic Microwave Polarization at Small Scale) is an experiment devoted to measuring the polarization of the CMBR. Its design and characteristics are presented
Ley de Ordenación de la Edificación y Seguro. Garantía decenal de daños
Màster de Direcció d'Entitats Asseguradores i Financeres, Universitat de Barcelona, Facultat d'Economia i Empresa, Curs: 2006-2007, Tutor: Santiago Ortega EspinosaDisfrutar de una vivienda digna es uno de los derechos fundamentales que recoge nuestra Constitución como expresión básica de la importancia que para el ciudadano tiene el alojamiento y el entorno urbano construido.
La edificación es pues un sector básico en cualquier país y su correcta regulación repercute directamente en el bienestar social.
A pesar de ello, hasta hace siete años, España no ha contado con una Ley de Ordenación de la Edificación (LOE) que establece las exigencias técnicas y administrativas, enumera los agentes y sus funciones y fija las responsabilidades y garantías, no siendo hasta el 2006/2007 cuando ha entrado en vigor el Código Técnico de la Edificación (CTE) como marco normativo por el que se regulan las exigencias básicas de calidad que deben cumplir los edificios.
El Sector Asegurador se ha visto desde el inicio de la LOE y previamente durante se reparación, muy involucrado en la misma para dar respuesta al establecimiento de las Garantías exigidas, recogiéndose en este trabajo los aspectos básicos que han permitido el desarrollo de las pólizas Decenales de Daños a la Edificación, su estado actual y el posible desarrollo futuro de las Garantías Trienales pendientes de nueva legislación
Assessing and monitoring intratumor heterogeneity in glioblastoma: how far has multimodal imaging come?
Glioblastoma demonstrates imaging features of intratumor heterogeneity that result from underlying heterogeneous biological properties. This stems from variations in cellular behavior that result from genetic mutations that either drive, or are driven by, heterogeneous microenvironment conditions. Among all imaging methods available, only T1-weighted contrast-enhancing and T2-weighted fluid-attenuated inversion recovery are used in standard clinical glioblastoma assessment and monitoring. Advanced imaging modalities are still considered emerging techniques as appropriate end points and robust methodologies are missing from clinical trials. Discovering how these images specifically relate to the underlying tumor biology may aid in improving quality of clinical trials and understanding the factors involved in regional responses to treatment, including variable drug uptake and effect of radiotherapy. Upon validation and standardization of emerging MR techniques, providing information based on the underlying tumor biology, these images may allow for clinical decision-making that is tailored to an individual's response to treatment.Stephen Price is funded by a Clinician Scientist Award from the National Institute for Health Research.This is the author accepted manuscript. The final version is available from Future Medicine via http://dx.doi.org/10.2217/cns.15.2
Spin-orbit hybrid entanglement of photons and quantum contextuality
We demonstrate electromagnetic quantum states of single photons and of
correlated photon pairs exhibiting "hybrid" entanglement between spin and
orbital angular momentum. These states are obtained from entangled photon pairs
emitted by spontaneous parametric down conversion, by employing a -plate for
coupling the spin and orbital degrees of freedom of a photon. Entanglement and
contextual quantum behavior (that is also non-local, in the case of photon
pairs) is demonstrated by the reported violation of the
Clauser-Horne-Shimony-Holt inequality. In addition a classical analog of the
hybrid spin-orbit photonic entanglement is reported and discussed.Comment: 5 pages, 3 figure
Vortex and half-vortex dynamics in a spinor quantum fluid of interacting polaritons
Spinorial or multi-component Bose-Einstein condensates may sustain fractional
quanta of circulation, vorticant topological excitations with half integer
windings of phase and polarization. Matter-light quantum fluids, such as
microcavity polaritons, represent a unique test bed for realising strongly
interacting and out-of-equilibrium condensates. The direct access to the phase
of their wavefunction enables us to pursue the quest of whether half vortices
---rather than full integer vortices--- are the fundamental topological
excitations of a spinor polariton fluid. Here, we are able to directly generate
by resonant pulsed excitations, a polariton fluid carrying either the half or
full vortex states as initial condition, and to follow their coherent evolution
using ultrafast holography. Surprisingly we observe a rich phenomenology that
shows a stable evolution of a phase singularity in a single component as well
as in the full vortex state, spiraling, splitting and branching of the initial
cores under different regimes and the proliferation of many vortex anti-vortex
pairs in self generated circular ripples. This allows us to devise the
interplay of nonlinearity and sample disorder in shaping the fluid and driving
the phase singularities dynamicsComment: New version complete with revised modelization, discussion and added
material. 8 pages, 7 figures. Supplementary videos:
https://drive.google.com/folderview?id=0B0QCllnLqdyBfmc2ai0yVF9fa2g2VnZodGUwemVkLThBb3BoOVRKRDJMS2dUdjlZdkRTQk
QUIJOTE Scientific Results. II. Polarisation Measurements of the Microwave Emission in the Galactic molecular complexes W43 and W47 and supernova remnant W44
We present Q-U-I JOint TEnerife (QUIJOTE) intensity and polarisation maps at
10-20 GHz covering a region along the Galactic plane 24<l<45 deg, |b|<8 deg.
These maps result from 210 h of data, have a sensitivity in polarisation of ~40
muK/beam and an angular resolution of ~1 deg. Our intensity data are crucial to
confirm the presence of anomalous microwave emission (AME) towards the two
molecular complexes W43 (22 sigma) and W47 (8 sigma). We also detect at high
significance (6 sigma) AME associated with W44, the first clear detection of
this emission towards a SNR. The new QUIJOTE polarisation data, in combination
with WMAP, are essential to: i) Determine the spectral index of the synchrotron
emission in W44, beta_sync =-0.62 +/-0.03, in good agreement with the value
inferred from the intensity spectrum once a free-free component is included in
the fit. ii) Trace the change in the polarisation angle associated with Faraday
rotation in the direction of W44 with rotation measure -404 +/- 49 rad/m2. And
iii) set upper limits on the polarisation of W43 of Pi_AME <0.39 per cent (95
per cent C.L.) from QUIJOTE 17~GHz, and <0.22 per cent from WMAP 41 GHz data,
which are the most stringent constraints ever obtained on the polarisation
fraction of the AME. For typical physical conditions (grain temperature and
magnetic field strengths), and in the case of perfect alignment between the
grains and the magnetic field, the models of electric or magnetic dipole
emissions predict higher polarisation fractions.Comment: Accepted for publication in MNRA
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