2,631 research outputs found

    An effectual template bank for the detection of gravitational waves from inspiralling compact binaries with generic spins

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    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" (m1+m2≲12 M⊙m_1 + m_2 \lesssim 12\,M_\odot) binaries, this template bank achieves effective fitting factors ∼0.92\sim0.92--0.990.99 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 ∼20−52%\sim20-52\%, 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

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    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 D≥2D \geq 2 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

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    Gamma Ray Bursts are being searched in many ground based experiments detecting the high energy component (GeV ÷\div 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

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    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

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    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

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    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

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    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

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    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

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    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
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