7,216 research outputs found
Data Processing for LISA's Laser Interferometer Tracking System (LITS)
The purpose of this paper is twofold. First, we will present recent results
on the data processing for LISA, including algorithms for elimination of clock
jitter noise and discussion of the generation of the data averages that will
eventually need to be telemetered to the ground. Second, we will argue, based
partly on these results, that a laser interferometer tracking system (LITS)
that employs independent lasers in each spacecraft is preferable for reasons of
simplicity to that in which the lasers in two of the spacecraft are locked to
the incoming beam from the third.Comment: 5 pages, Proceedings of the Third LISA Symposium (Golm, Germany,
2000
Characterising gravitational wave stochastic background anisotropy with Pulsar Timing Arrays
Detecting a stochastic gravitational wave background, particularly radiation
from individually unresolvable super-massive black hole binary systems, is one
of the primary targets for Pulsar Timing Arrays. Increasingly more stringent
upper limits are being set on these signals under the assumption that the
background radiation is isotropic. However, some level of anisotropy may be
present and the characterisation of the power at different angular scales
carries important information. We show that the standard analysis for isotropic
backgrounds can be generalised in a conceptually straightforward way to the
case of generic anisotropic background radiation by decomposing the angular
distribution of the gravitational wave power on the sky into multipole moments.
We introduce the concept of generalised overlap reduction functions which
characterise the effect of the anisotropy multipoles on the correlation of the
timing residuals from the pulsars timed by a Pulsar Timing Array. In a search
for a signal characterised by a generic anisotropy, the generalised overlap
reduction functions play the role of the so-called Hellings and Downs curve
used for isotropic radiation. We compute the generalised overlap reduction
functions for a generic level of anisotropy and Pulsar Timing Array
configuration. We also provide an order of magnitude estimate of the level of
anisotropy that can be expected in the background generated by super-massive
black hole binary systems.Comment: 12 pages plus 5 page Appendix. Accepted to PR
Analysis of the first IPTA Mock Data Challenge by the EPTA timing data analysis working group
This is a summary of the methods we used to analyse the first IPTA Mock Data
Challenge (MDC), and the obtained results. We have used a Bayesian analysis in
the time domain, accelerated using the recently developed ABC-method which
consists of a form of lossy linear data compression. The TOAs were first
processed with Tempo2, where the design matrix was extracted for use in a
subsequent Bayesian analysis. We used different noise models to analyse the
datasets: no red noise, red noise the same for all pulsars, and individual red
noise per pulsar. We sampled from the likelihood with four different samplers:
"emcee", "t-walk", "Metropolis-Hastings", and "pyMultiNest". All but emcee
agreed on the final result, with emcee failing due to artefacts of the
high-dimensionality of the problem. An interesting issue we ran into was that
the prior of all the 36 (red) noise amplitudes strongly affects the results. A
flat prior in the noise amplitude biases the inferred GWB amplitude, whereas a
flat prior in log-amplitude seems to work well. This issue is only apparent
when using a noise model with individually modelled red noise for all pulsars.
Our results for the blind challenges are in good agreement with the injected
values. For the GWB amplitudes we found h_c = 1.03 +/- 0.11 [10^{-14}], h_c =
5.70 +/- 0.35 [10^{-14}], and h_c = 6.91 +/- 1.72 [10^{-15}], and for the GWB
spectral index we found gamma = 4.28 +/- 0.20, gamma = 4.35 +/- 0.09, and gamma
= 3.75 +/- 0.40. We note that for closed challenge 3 there was quite some
covariance between the signal and the red noise: if we constrain the GWB
spectral index to the usual choice of gamma = 13/3, we obtain the estimates:
h_c = 10.0 +/- 0.64 [10^{-15}], h_c = 56.3 +/- 2.42 [10^{-15}], and h_c = 4.83
+/- 0.50 [10^{-15}], with one-sided 2 sigma upper-limits of: h_c <= 10.98
[10^{-15}], h_c <= 60.29 [10^{-15}], and h_c <= 5.65 [10^{-15}].Comment: 10 pages, 5 figure
Infinite index extensions of local nets and defects
Subfactor theory provides a tool to analyze and construct extensions of
Quantum Field Theories, once the latter are formulated as local nets of von
Neumann algebras. We generalize some of the results of [LR95] to the case of
extensions with infinite Jones index. This case naturally arises in physics,
the canonical examples are given by global gauge theories with respect to a
compact (non-finite) group of internal symmetries. Building on the works of
Izumi, Longo, Popa [ILP98] and Fidaleo, Isola [FI99], we consider generalized
Q-systems (of intertwiners) for a semidiscrete inclusion of properly infinite
von Neumann algebras, which generalize ordinary Q-systems introduced by Longo
[Lon94] to the infinite index case. We characterize inclusions which admit
generalized Q-systems of intertwiners and define a braided product among the
latter, hence we construct examples of QFTs with defects (phase boundaries) of
infinite index, extending the family of boundaries in the grasp of [BKLR16].Comment: 50 page
Eccentric double white dwarfs as LISA sources in globular clusters
We consider the formation of double white dwarfs (DWDs) through dynamical
interactions in globular clusters. Such interactions can give rise to eccentric
DWDs, in contrast to the exclusively circular population expected to form in
the Galactic disk. We show that for a 5-year Laser Interferometer Space Antenna
(LISA) mission and distances as far as the Large Magellanic Cloud, multiple
harmonics from eccentric DWDs can be detected at a signal-to-noise ratio higher
than 8 for at least a handful of eccentric DWDs, given their formation rate and
typical lifetimes estimated from current cluster simulations. Consequently the
association of eccentricity with stellar-mass LISA sources does not uniquely
involve neutron stars, as is usually assumed. Due to the difficulty of
detecting (eccentric) DWDs with present and planned electromagnetic
observatories, LISA could provide unique dynamical identifications of these
systems in globular clusters.Comment: Published in ApJ 665, L5
Tratamiento de la artropatÃa crónica hemofÃlica mediante inyecciones intraarticulares de cortisona
Se evaluaron las historias clÃnicas de 34 pacientes hemofÃlicos con artropatÃa crónica
severa (25 grado III y 9 grado IV), todos ellos con deformidades axiales, atrofia muscular y limitación
del movimiento articular (31 rodillas, 2 tobillos y 2 hombros), a quienes se les inyectó intraarticularmcnte
entre 1 y 9 dosis de cortisona de liberación prolongada con intervalos de 3 semanas.
Se les realizó una evaluación subjetiva y objetiva en base a los siguientes parámetros: bueno: no dolor,
incremento en los rangos de movimiento y total integración a las actividades de la vida diaria;
regular: disminución del dolor, igual rango de movilidad y actividades de la vida diaria limitadas, y
malo: persistencia del dolor, disminución de los rangos articulares y gran limitación para las actividades
de la vida diaria. En la evaluación subjetiva obtuvimos 19 pacientes con buenos resultados,
12 regulares y 4 malos; en la evaluación objetiva obtuvimos 22 pacientes con buenos resultados, 9 regulares
y 4 malos. Según los resultados obtenidos, la cortisona intraarticular parece ser un excelente
tratamiento paliativo en la artropatÃa crónica hemofÃlica.Thirty four patients with chronic haemophilic arthropathy (25 grade III and 9 grade
IV), having all axial deformities, muscular atrophy, and limitation of range of motion in the joint
(31 knees, 2 ankles and 2 shoulders) were injected intrarticulary at 3 weeks interval with a long
standing cortisone from 1 to 9 injections. Subjective and objective evaluation parameters were
assessed considering as good no pain, increase range of motion and normal activity of daily life;
fair with less pain, same range of motion and slight diminution of activity of daily life; and bad with
persistence of pain, less range of motion and greater diminution of activity. We obtained in subjective
evaluation 19 good results, 12 fair, and 4 bad; in objective evaluation we obtained 22 good
results, 9 fair, and 4 bad. In conclusion, intrarticular cortisone seems to be a reliable treatment of
chronic haemophilic arthropathy
Optical properties of V2O3 in its whole phase diagram
Vanadium sesquioxide V2O3 is considered a textbook example of Mott-Hubbard
physics. In this paper we present an extended optical study of its whole
temperature/doping phase diagram as obtained by doping the pure material with
M=Cr or Ti atoms (V1-xMx)2O3. We reveal that its thermodynamically stable
metallic and insulating phases, although macroscopically equivalent, show very
different low-energy electrodynamics. The Cr and Ti doping drastically change
both the antiferromagnetic gap and the paramagnetic metallic properties. A
slight chromium content induces a mesoscopic electronic phase separation, while
the pure compound is characterized by short-lived quasiparticles at high
temperature. This study thus provides a new comprehensive scenario of the
Mott-Hubbard physics in the prototype compound V2O3
Precision Farming: Barriers of Variable Rate Technology Adoption in Italy
Research dealing with the adoption of various precision agriculture technologies has shown that guidance and recording tools are more widespread than reactive ones (such as variable rate technology), with much lower utilization rates in European case studies. This study aims to analyze the propensity to innovate variable rate technologies among young Italian farmers. A cluster analysis was carried out revealing four groups. The first two groups represent non-adopters who think technological innovation is very complex from a technical point of view, as well as not very accessible as capital-intensive technology. The third and fourth groups represent adopters. The third reports an early level of adoption, still considering the cost of access a major barrier to technology implementation. The fourth, on the other hand, shows a more intensive level and considers the lack of institutional support a major limitation. The cluster with the most intensive adoption is characterized by the youngest age group, the farms with the largest size, and a prevalence of female entrepreneurs. The need for management training in day-to-day business operations upon adoption is detected for all groups. This paper identified relevant drivers and barriers in characterizing the adopting farm of variable rate technologies. Results may offer insights to the policy maker to better calibrate support interventions
Cohabitation of settlements among crested porcupine (Hystrix cristata), red fox (Vulpes vulpes) and European badger (Meles meles)
In Italy, porcupines, badgers and red foxes share the same settlements. However, there is lack of informa-tion concerning their cohabitation. From 2012 to 2019, cohabitation by these three mammals was studied using camera-trapping and was found to occur only between porcupines and badgers, even in the presence of porcupettes. Cohabitation was associated with aggressive interaction between porcupines and badg-ers. Foxes were found to be scavengers of porcupine carcasses. Cohabitation among these semi-fossorial mammals and scavenging behaviour could play a role in disease transmission, including zoonotic diseases
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