66 research outputs found

    Geophysical measurements for site response investigation : preliminary results on the island of Malta

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    The main goal of this study is to investigate the dynamic properties of main lithotypes outcropping on the island of Malta and to evaluate the general features of the local seismic response through the combined use of geophysical methods based on Rayleigh waves and horizontal to vertical noise spectral ratios. These kind of studies have unfortunately never been undertaken in Malta and, therefore, no shear wave velocity values and fundamental frequency of outcropping lithotypes have been published. The proposed preliminary results represent a valid set of data useful for evaluating seismic hazard and risk for the Maltese islands. Even if the seismic activity around the archipelago is generally of low to moderate magnitude the islands in the past were struck by large events in Sicily and the Hellenic arc resulting in considerable damage.peer-reviewe

    Evaluation of seismic site response in the Maltese archipelago

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    The investigation of local ground conditions is an important part of seismic hazard assessment (Fäh et al., 2003). It is now well–established that earthquake ground shaking is not only a function of the earth- quake magnitude and epicentral distance, but also of the site conditions, including soft layers in the sub–soil stratification and topographical features. Local geology can greatly alter the seismic waves from earthquakes by amplifying their amplitude, changing the frequency content and increasing the shaking duration during an earthquake (Kramer, 1996). In fact, several unconsolidated soft sites have suffered significantly greater damage than rock sites. One case was the 1985 Michoacán earthquake which showed low peak ground acceleration near the epicenter, yet caused severe damage in Mexico City, which is found more than 350 km away and is characterized by soft shallow sediments (Campillo et al., 1989).peer-reviewe

    Post-Operative Functional Outcomes in Early Age Onset Rectal Cancer

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    Background: Impairment of bowel, urogenital and fertility-related function in patients treated for rectal cancer is common. While the rate of rectal cancer in the young (<50 years) is rising, there is little data on functional outcomes in this group. Methods: The REACCT international collaborative database was reviewed and data on eligible patients analysed. Inclusion criteria comprised patients with a histologically confirmed rectal cancer, <50 years of age at time of diagnosis and with documented follow-up including functional outcomes. Results: A total of 1428 (n=1428) patients met the eligibility criteria and were included in the final analysis. Metastatic disease was present at diagnosis in 13%. Of these, 40% received neoadjuvant therapy and 50% adjuvant chemotherapy. The incidence of post-operative major morbidity was 10%. A defunctioning stoma was placed for 621 patients (43%); 534 of these proceeded to elective restoration of bowel continuity. The median follow-up time was 42 months. Of this cohort, a total of 415 (29%) reported persistent impairment of functional outcomes, the most frequent of which was bowel dysfunction (16%), followed by bladder dysfunction (7%), sexual dysfunction (4.5%) and infertility (1%). Conclusion: A substantial proportion of patients with early-onset rectal cancer who undergo surgery report persistent impairment of functional status. Patients should be involved in the discussion regarding their treatment options and potential impact on quality of life. Functional outcomes should be routinely recorded as part of follow up alongside oncological parameters

    Observation of gravitational waves from the coalescence of a 2.5−4.5 M⊙ compact object and a neutron star

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    Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network

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    Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO--Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects

    Search for eccentric black hole coalescences during the third observing run of LIGO and Virgo

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    Despite the growing number of confident binary black hole coalescences observed through gravitational waves so far, the astrophysical origin of these binaries remains uncertain. Orbital eccentricity is one of the clearest tracers of binary formation channels. Identifying binary eccentricity, however, remains challenging due to the limited availability of gravitational waveforms that include effects of eccentricity. Here, we present observational results for a waveform-independent search sensitive to eccentric black hole coalescences, covering the third observing run (O3) of the LIGO and Virgo detectors. We identified no new high-significance candidates beyond those that were already identified with searches focusing on quasi-circular binaries. We determine the sensitivity of our search to high-mass (total mass M>70 M⊙) binaries covering eccentricities up to 0.3 at 15 Hz orbital frequency, and use this to compare model predictions to search results. Assuming all detections are indeed quasi-circular, for our fiducial population model, we place an upper limit for the merger rate density of high-mass binaries with eccentricities 0<e≤0.3 at 0.33 Gpc−3 yr−1 at 90\% confidence level

    Ultralight vector dark matter search using data from the KAGRA O3GK run

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    Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM

    Improvement in uterine artery doppler indices via hysteroscopic metroplasty

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    Objective: the objective of our research was to study uterine artery doppler indices and their evolution over time after metroplasty and subsequent pregnancy in patients whose septate uterus was the only explanation for infertility. Materials and Methods: a retrospective study. The uterine arteries of 78 patients with septate uteri were evaluated using endovaginal color doppler ultrasound before and after metroplasty. Fifty-one patients became pregnant after metroplasty and were selected as study group, pregnancy occurred within 17 months. By comparing uterine artery doppler indices before and after metroplasty, we observed that the resistive index (RI) and pulsatility index (PI) post surgery were significantly lower compared to pre-metroplasty levels. Results: all pregnant women in the study Group showed uterine resistive indexes within normal ranges, they all underwent scheduled cesarean intervention. Gestational evolution was normal in all patients (mean score of Apgar and birth weight); no neonatal complications were observed. Conclusion: metroplastic intervention in women with septate uterus as the sole cause of infertility may be a plausible alternative for patients wishing to carry a pregnancy

    Hysteroscopy as an elective tool in abnormal uterine bleeding in perimenopausal women.

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    Abnormal Uterine Bleeding is a very frequent pathology particularly in perimenopausal age (> or = 45 years). The Authors report the experience of the 2nd Department of Ob/Gyn. of Rome University "La Sapienza" from January 1985 up to September 1991. The hysteroscopic evaluation of 789 patients in perimenopausal age is reviewed. The Authors analyze in detail the main cause of metrorrhagia describing the hysteroscopic aspect and relative incidence. Finally, some considerations concerning the great usefulness that a simple and accurate diagnostic investigation such as hysteroscopy represents in a routine diagnostic procedure, are reported
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