2,632 research outputs found
Estimation of the gravitational wave polarizations from a non template search
Gravitational wave astronomy is just beginning, after the recent success of
the four direct detections of binary black hole (BBH) mergers, the first
observation from a binary neutron star inspiral and with the expectation of
many more events to come. Given the possibility to detect waves from not
perfectly modeled astrophysical processes, it is fundamental to be ready to
calculate the polarization waveforms in the case of searches using non-template
algorithms. In such case, the waveform polarizations are the only quantities
that contain direct information about the generating process. We present the
performance of a new valuable tool to estimate the inverse solution of
gravitational wave transient signals, starting from the analysis of the signal
properties of a non-template algorithm that is open to a wider class of
gravitational signals not covered by template algorithms. We highlight the
contributions to the wave polarization associated with the detector response,
the sky localization and the polarization angle of the source. In this paper we
present the performances of such method and its implications by using two main
classes of transient signals, resembling the limiting case for most simple and
complicated morphologies. Performances are encouraging, for the tested
waveforms: the correlation between the original and the reconstructed waveforms
spans from better than 80% for simple morphologies to better than 50% for
complicated ones. For a not-template search this results can be considered
satisfactory to reconstruct the astrophysical progenitor
Equation of state at high densities and modern compact star observations
Recently, observations of compact stars have provided new data of high
accuracy which put strong constraints on the high-density behaviour of the
equation of state of strongly interacting matter otherwise not accessible in
terrestrial laboratories. The evidence for neutron stars with high mass (M =2.1
+/- 0.2 M_sun for PSR J0751+1807) and large radii (R > 12 km for RX J1856-3754)
rules out soft equations of state and has provoked a debate whether the
occurence of quark matter in compact stars can be excluded as well. In this
contribution it is shown that modern quantum field theoretical approaches to
quark matter including color superconductivity and a vector meanfield allow a
microscopic description of hybrid stars which fulfill the new, strong
constraints. The deconfinement transition in the resulting stiff hybrid
equation of state is weakly first order so that signals of it have to be
expected due to specific changes in transport properties governing the
rotational and cooling evolution caused by the color superconductivity of quark
matter. A similar conclusion holds for the investigation of quark deconfinement
in future generations of nucleus-nucleus collision experiments at low
temperatures and high baryon densities such as CBM @ FAIR.Comment: 6 pages, 2 figures, accepted for publication in J. Phys. G. (Special
Issue
Improving Performance of QUIC in WiFi
QUIC is a new transport protocol under standardization since 2016. Initially developed by Google as an experiment, the protocol is already deployed in large-scale, thanks to its support in Chromium and Google's servers. In this paper we experimentally analyze the performance of QUIC in WiFi networks. We perform experiments using both a controlled WiFi testbed and a production WiFi mesh network. In particular, we study how QUIC interplays with MAC layer features such as IEEE 802.11 frame aggregation. We show that the current implementation of QUIC in Chromium achieves sub-optimal throughput in wireless networks. Indeed, burstiness in modern WiFi standards may improve network performance, and we show that a Bursty QUIC (BQUIC), i.e., a customized version of QUIC that is targeted to increase its burstiness, can achieve better performance in WiFi. BQUIC outperforms the current version of QUIC in WiFi, with throughput gains ranging between 20% to 30%
The nutraceuticals : a new therapeutic strategy in the management of digestive and respiratory disorders
Nutraceuticals represents an intriguing challenge in clinical practice. They are currently used worldwide in all fields of Medicine. The present Supplement reports two Italian surveys concerning a probiotic mixture employed in patients with chronic intestinal disorders and a Medical Device used in patients with upper respiratory diseases. These surveys were conducted on a group of Italian gastroenterologists and on a group of Italian otolaryngologists respectively. Both surveys demonstrated that these compounds may represent a useful therapeutic option in clinical practice
Prospects for intermediate mass black hole binary searches with advanced gravitational-wave detectors
We estimated the sensitivity of the upcoming advanced, ground-based
gravitational-wave observatories (the upgraded LIGO and Virgo and the KAGRA
interferometers) to coalescing intermediate mass black hole binaries (IMBHB).
We added waveforms modeling the gravitational radiation emitted by IMBHBs to
detectors' simulated data and searched for the injected signals with the
coherent WaveBurst algorithm. The tested binary's parameter space covers
non-spinning IMBHBs with source-frame total masses between 50 and 1050
and mass ratios between and 1. We found that
advanced detectors could be sensitive to these systems up to a range of a few
Gpc. A theoretical model was adopted to estimate the expected observation
rates, yielding up to a few tens of events per year. Thus, our results indicate
that advanced detectors will have a reasonable chance to collect the first
direct evidence for intermediate mass black holes and open a new, intriguing
channel for probing the Universe over cosmological scales.Comment: 9 pages, 4 figures, corrected the name of one author (previously
misspelled
Strange Exotic States and Compact Stars
We discuss the possible appearance of strange exotic multi-quark states in
the interior of neutron stars and signals for the existence of strange quark
matter in the core of compact stars. We show how the in-medium properties of
possible pentaquark states are constrained by pulsar mass measurements. The
possibility of generating the observed large pulsar kick velocities by
asymmetric emission of neutrinos from strange quark matter in magnetic fields
is outlined.Comment: 10 pages, invited talk given at the International Conference on
Strangeness in Quark Matter 2006 (SQM2006), UCLA, USA, March 26-31, 2006,
Journal of Physics G in press, refs. adde
- …