2,631 research outputs found
An effectual template bank for the detection of gravitational waves from inspiralling compact binaries with generic spins
We report the construction of a three-dimensional template bank for the
search for gravitational waves from inspiralling binaries consisting of
spinning compact objects. The parameter space consists of two dimensions
describing the mass parameters and one "reduced-spin" parameter, which
describes the secular (non-precessing) spin effects in the waveform. The
template placement is based on an efficient stochastic algorithm and makes use
of the semi-analytical computation of a metric in the parameter space. We
demonstrate that for "low-mass" () binaries,
this template bank achieves effective fitting factors --
towards signals from generic spinning binaries in the advanced detector era
over the entire parameter space of interest (including binary neutron stars,
binary black holes, and black hole-neutron star binaries). This provides a
powerful and viable method for searching for gravitational waves from generic
spinning low-mass compact binaries. Under the assumption that spin magnitudes
of black-holes [neutron-stars] are uniformly distributed between 0--0.98 [0 --
0.4] and spin angles are isotropically distributed, the expected improvement in
the average detection volume (at a fixed signal-to-noise-ratio threshold) of a
search using this reduced-spin bank is , as compared to a search
using a non-spinning bank.Comment: Minor changes, version appeared in Phys. Rev.
Magnetism and domain formation in SU(3)-symmetric multi-species Fermi mixtures
We study the phase diagram of an SU(3)-symmetric mixture of three-component
ultracold fermions with attractive interactions in an optical lattice,
including the additional effect on the mixture of an effective three-body
constraint induced by three-body losses. We address the properties of the
system in by using dynamical mean-field theory and variational Monte
Carlo techniques. The phase diagram of the model shows a strong interplay
between magnetism and superfluidity. In the absence of the three-body
constraint (no losses), the system undergoes a phase transition from a color
superfluid phase to a trionic phase, which shows additional particle density
modulations at half-filling. Away from the particle-hole symmetric point the
color superfluid phase is always spontaneously magnetized, leading to the
formation of different color superfluid domains in systems where the total
number of particles of each species is conserved. This can be seen as the SU(3)
symmetric realization of a more general tendency to phase-separation in
three-component Fermi mixtures. The three-body constraint strongly disfavors
the trionic phase, stabilizing a (fully magnetized) color superfluid also at
strong coupling. With increasing temperature we observe a transition to a
non-magnetized SU(3) Fermi liquid phase.Comment: 36 pages, 17 figures; Corrected typo
Detection of GRB signals with Fluorescence Detectors
Gamma Ray Bursts are being searched in many ground based experiments
detecting the high energy component (GeV TeV energy range) of the photon
bursts. In this paper, Fluorescence Detectors are considered as possible
candidate devices for these searches. It is shown that the GRB photons induce
fluorescence emission of UV photons on a wide range of their spectrum. The
induced fluorescence flux is dominated by GRB photons from 0.1 to about 100 MeV
and, once the extinction through the atmosphere is taken into account, it is
distributed over a wide angular region. This flux can be detected through a
monitor of the diffuse photon flux, provided that its maximum value exceeds a
threshold value, that is primarily determined by the sky brightness above the
detector. The feasibility of this search and the expected rates are discussed
on the basis of the current GRB observations and the existing fluorescence
detectors.Comment: 16 pages 9 eps figure
A novel Digital OTA topology with 66-dB DC Gain and 12.3-kHz Bandwidth
The paper introduces an enhanced digital OTA topology which allows increasing the DC gain thanks to the adoption of an inverter-based output stage. Moreover, a new equivalent small-signal model is proposed which allows to simplify the circuit analysis and paves the way to new frequency compensation strategies. Designed using a 28-nm standard CMOS technology and working at 0.3-V power supply, post-layout simulations show a 66-dB gain and a 12.3-kHz gain bandwidth product while driving a 250-pF capacitive load. As compared to other ultra-low-voltage OTAs in literature, an increase of small and large signal performance, respect to area occupation, equal to 4.6X and 1.5X, respectively, is obtained
Triggering mechanisms of static stress on Mount Etna volcano. An application of the boundary element method
In the last thirty years, numerous eruptions and associated deformation episodes have occurred at Mt. Etna volcano. Datasets recorded by continuous monitoring of these episodes provide a unique opportunity to study the relationships between volcanism, flank instability and faulting activity. We have investigated the stress triggering mechanism between magmatic reservoir inflation, intrusive episodes and flank dynamics. Using three-dimensional numerical Boundary Elements Models we simulated volcano-tectonic events and calculated Coulomb stress changes. Using this modeling approach, we analyzed four realistic scenarios that are representative of recent kinematics occurring at Mt. Etna. The main results obtained highlight how (1) the inflation of a deep spherical magma source transfers elastic stress to a sliding plane and faults (2) the opening of the NE Rift and S Rift
(to a less efficient extent) favor movements of the instable sector and may encourage seismicity on the eastern flank faults, and (3) flank instability may trigger the uprising of magma. Defining the effects of the elastic stress transfer and relationships among the main forces acting on volcano, may help to forecast possible eruption scenarios during future episodes of unrest at Mount Etna and provide an important tool for decision makers during volcanic emergencies involving the highly populated areas of the volcano
Monte Carlo study of fermionic trions in a square lattice with harmonic confinement
We investigate the strong-coupling limit of a three-component Fermi mixture
in an optical lattice with attractive interactions. In this limit bound states
(trions) of the three components are formed. We derive an effective Hamiltonian
for these composite fermions and show that it is asymptotically equivalent to
an antiferromagnetic Ising model. By using Monte-Carlo simulations, we
investigate the spatial arrangement of the trions and the formation of a
trionic density wave (CDW), both in a homogeneous lattice and in the presence
of an additional harmonic confinement. Depending on the strength of the
confinement and on the temperature, we found several scenarios for the trionic
distribution, including coexistence of disordered trions with CDW and band
insulator phases. Our results show that, due to a proximity effect, staggered
density modulations are induced in regions of the trap where they would not
otherwise be present according to the local density approximation.Comment: 10 pages, 8 figure
Seismic and Infrasound Signals at Mt. Etna: Modelling the North-East Crater Conduit and its Relation with the 2008-2009 Eruption Feeding System
On 13 May 2008, an eruption began at Mt. Etna from an eruptive fissure that opened on the upper
eastern flank of the volcano. During 12-13 May, 157 infrasonic events, together with the related
seismic transients, were collected. We carried out several analyses to obtain dominant frequencies,
pseudospectrograms, peak-to-peak amplitudes, source locations and time lags between infrasonic
and seismic events. Spectra of the infrasonic events show two main spectral peaks in the frequency
bands ~0.4-0.7 Hz and 1.5-2.0 Hz, respectively. Both infrasonic and seismic events were separately
located below the North-East Crater, where no eruptive activity was observed. Moreover,
significant changes in infrasound spectral content, as well as in the infrasonic-seismic lags, were
found a few hours before the beginning of the eruption. On the basis of the collected information
the infrasound source mechanism was modelled as a superposition of pipe and Helmholtz
resonance, also leading to outline the geometry of the shallower portion of the North-East Crater
plumbing system. The occurrence of these seismo-infrasonic events together with other geological
and geophysical evidences, led us to inferring a direct link between North-East Crater activity and
the eruptive fissure. Further, based on variations over time of both spectral features and seismicinfrasonic
time lag, shallowing phenomena of the free magma column inside North-East Crater
conduit were hypothesized. Such an uprise of magma was likely caused by a pressure increase
inside the plumbing system occurring before the beginning of the 2008-2009 eruption
Long-term active problems in patients with cloacal exstrophy: a systematic review
BACKGROUND: Cloacal exstrophy (CE) is the most severe end of the Exstrophy-Epispadias Complex malformations spectrum. Improvements in postnatal management and well-established operative techniques have resulted in survival rates approaching 100%. This systematic review aims to define the prevalence of long-term active medical problems affecting CE patients after the first decade of life. METHODS: PubMed/Medline, Embase, Scopus, and ISI Web of Knowledge databases were used for the literature search. Original articles related to medical, surgical, and psychosocial long-term problems in CE patients >10 years of age were included in the study. Quality assessment of the articles was performed through the Newcastle-Ottawa Scale. Prevalence estimates and 95% CI were assessed for each outcome. RESULTS: Twelve studies were included. The most common long-term active problems identified were: urinary incontinence with a prevalence ranging from 9.1% to 85%; sexual function issues related to vaginal anomalies with a prevalence ranging from 8.3% to 71.3%, and uterine anomalies, with a prevalence from 14.3% to 71%; gender identity issues in 46, XY patients raised female had a prevalence from 11.1% to 66.7%. There is no documented history of paternity. Impairment of ambulatory capacity was recorded in 13.8% of patients. Only one paper studied psychological well-being, reporting significantly higher levels of depression among gender reassigned patients. CONCLUSIONS: Teenagers and adults born with CE have well defined long-term problems compared to the general population. Recognition and expert management are crucial to improve care and quality of life during and after the transition into adulthood
Pelvic arterial embolization for postpartum hemorrhage: long term results of a single center experience in 29,091 deliveries
Purpose of investigation: To evaluate the rate of all postpartum hemorrhages (PPHs) treated with uterine embolization in a third level delivery center. Materials and Methods: Since January 2008 to March 2014, 29,091 deliveries were registered in the present hospital in Bergamo, Italy. Among these deliveries, 2,002 cases (6.8%) of PPHs occurred. Seventy-three patients with severe obstetric hemorrhage underwent uterine artery embolization (UAE) (47 cases, 1.61/1,000 deliveries) or hysterectomy (26 cases, 0.89/1,000 deliveries). All identified cases were followed up by telephone on January 2015 in order to evaluate long term results. Results: Embolization was performed successfully in 45 patients (95.7%). Two women underwent total abdominal hysterectomy: one patient for uterine atony and one for adherent placenta. In the follow up all the women interviewed reported the return of their menstrual cycle and 95.2% of women reported regular cycles. Conclusions: Embolization showed a success rate of 95.7%. For this reason, in the authors’ opinion, it is the best choice as second line treatment of PPH, when patient is hemodynamically stable
- …