21 research outputs found
A robotized environmental sensor array for gravitational wave observatory sites
No full textA movable array of environmental sensors is intended for the feed-forward cancellation of the Newtonian noise generated by atmospheric density fluctuations and seismic displacements at the Virgo gravitational wave detector site, with the prospect of being used at the sites of future 3rd generation detectors. Each robot unit is equipped with a seismic sensor - optionally also a microphone and a magnetometer - for low-noise and low-frequency observations. The robots need to move autonomously in the experimental areas indoors, avoiding obstacles to reach the assigned positions where they start the data acquisition process. Then, the data will be transferred wirelessly to the control software that elaborates them and imparts to all robots the command to move to new optimal positions. Essential requirements of the system are accuracy in positioning and timing. The project is described highlighting the technical choices and their implementation
Analysis methods for gravitational wave from binary neutron star coalescences: investigation on the post-merger phase
No full textThe coalescence of binary neutron stars (BNS) is amongst the most promising sources for advanced gravitational wave (GW) detectors. The forthcoming addition of the advanced Virgo interferometer to the LIGO detector network will greatly improve the estimation of GW characteristics and therefore the capabilities to test features in the GW signal emitted by the coalescence of a NS binary. Such an observation can constrain the equation
of state of these stars in at least two ways: by investigating smaller effects on top of the signal from the inspiral phase due to the tidal deformability of the components and by characterizing the emission from the possible highly excited NS remnant after the merger. Both methods promise to probe matter up to yet unknown and unexplored supranuclear densities, provided that the signal-to-noise ratio (SNR) at which the single GW is detected is sufficiently high or that the results from more detections can be combined together. Depending on mass and Equation of State (EoS) of the NS progenitors,
the final fate of the merger can produce either a prompt collapse to black hole (BH) or a massive NS remnant. In the latter case, the merger remnant could be a short-lived, hypermassive NS (HMNS) collapsing to a BH within a few tens of ms after merger, or a long-lived NS, which in turn can be either supramassive (SMNS), i.e. collapsing to a BH on much longer timescales of order of seconds, or even a stable NS. These remnants will be highly excited, showing transient nonaxisymmetric deformations and quadrupolar oscillations, which are expected to emit GWs peaked in the frequency range around 2-3 kHz. The observation of these Post Merger (PM) fingerprints, would allow to constrain the EoS and at the same time to estimate combinations of stellar parameters, such as
mass and radius of the two objects.
With these motivations, my PhD thesis addressed the development of a new data analysis tool in order to investigate the GW signal emitted during the PM phase following a NS coalescence. The analysis procedure is developed inside the framework of the Coherent Wave Burst (cWB) pipeline which is employed by LIGO and Virgo collaboration to search for burst signals, i.e. it makes minimal assumption on the GW morphology and provides a robust coverage of generic GW transients
Emerging Evidence and Treatment Perspectives from Randomized Clinical Trials in Systemic Sclerosis: Focus on Interstitial Lung Disease
No full textSystemic sclerosis (SSc) is a complex rare autoimmune disease with heterogeneous clinical manifestations. Currently, interstitial lung disease (ILD) and cardiac involvement (including pulmonary arterial hypertension) are recognized as the leading causes of SSc-associated mortality. New molecular targets have been discovered and phase II and phase III clinical trials published in the last 5 years on SSc-ILD will be discussed in this review. Details on the study design; the drug tested and its dose; the inclusion and exclusion criteria of the study; the concomitant immunosuppression; the outcomes and the duration of the study were reviewed. The two most common drugs used for the treatment of SSc-ILD are cyclophosphamide and mycophenolate mofetil, both supported by randomized controlled trials. Additional drugs, such as nintedanib and tocilizumab, have been approved to slow pulmonary function decline in SSc-ILD. In this review, we discuss the therapeutic alternatives for SSc management, offering the option to customize the design of future studies to stratify SSc patients and provide a patient-specific treatment according to the new emerging pathogenic features of SSc-ILD
Morphology-independent characterization method of postmerger gravitational wave emission from binary neutron star coalescences
No full textGravitational waves (GWs) emitted during the coalescence of binary neutron star (BNS) systems carry information about the equation of state (EoS) describing the extremely dense matter inside neutron stars (NSs). In particular, the EoS determines the fate of the binary after the merger: a prompt collapse to black hole (BH), or the formation of a NS remnant that is either stable or survives up to a few seconds before collapsing to a BH. Determining the
evolution of a BNS system will therefore place strong constraints on the EoS. We present a morphology-independent method, developed in the framework of the coherentWaveBurst analysis of signals from ground-based interferometric
detectors of GWs. The method characterizes the time-frequency postmerger GW emission from a BNS system, and determines whether, after the merger, it formed a remnant NS or promptly collapsed to a BH. We measure the followwing quantities to characterize the postmerger emission: ratio of signal energies and match of luminosity profile in different frequency bands, weighted central frequency and bandwidth. From these quantities, based on the study of sig nals simulated through injections of numerical relativity waveforms, we build a statistics to discriminate between the different scenarios after the merger. Finally, we test our method on a set of signals simulated with new models, to
estimate its efficiency as a function of the source distance
Stratification of COVID-19 Patients with Moderate-to-Severe Hypoxemic Respiratory Failure for Response to High-Flow Nasal Cannula: A Retrospective Observational Study
No full textBackground and Objectives: In patients with COVID-19, high-flow nasal cannula (HFNC) and continuous positive airway pressure (CPAP) are widely applied as initial treatments for moderate-to-severe acute hypoxemic respiratory failure. The aim of the study was to assess which respiratory supports improve 28-day mortality and to identify a predictive index of treatment response. Materials and Methods: This is a single-center retrospective observational study including 159 consecutive adult patients with COVID-19 and moderate-to-severe hypoxemic acute respiratory failure. Results: A total of 159 patients (82 in the CPAP group and 77 in the HFNC group) were included in the study. Mortality within 28 days was significantly lower with HFNC compared to CPAP (16.8% vs. 50%), while ICU admission and tracheal intubation within 28 days were significantly higher with CPAP compared to HFNC treatment (32% vs. 13%). We identified an index for survival in HFNC by including three variables easily available at admission (LDH, age, and respiratory rate) and the PaO2/FiO2 ratio at 48 h. The index showed high discrimination for survival with an AUC of 0.88, a negative predictive value of 86%, and a positive predictive value of 95%. Conclusions: Treatment with HFNC appears to be associated with greater survival and fewer ICU admission than CPAP. LDH, respiratory rate, age, and PaO2/FiO2 at 48 h were independently associated with survival and an index based on these variables allows for the prediction of treatment success and the assessment of patient allocation to the appropriate intensity of care after 48 h. Further research is warranted to determine effects on other outcomes and to assess the performance of the index in larger cohorts
The Efficacy of Sequential Biologic Agents in Refractory Rheumatoid Arthritis After Failure of Initial DMARD and Anti-Tumor Necrosis Factor Therapy
No full textIntroduction/Objective: The efficacy of biologic therapy in the treatment of rheumatoid arthritis (RA) has been well-established but, in practice, a quarter of patients will either not respond to the first biologic agent or will suffer an adverse event requiring a switch to a different drug. While clinical guidelines exist to help guide therapy and previous studies have examined sequential use of anti-TNF agents, there is little data to inform a multiple switch strategy. Our aim was to measure the efficacy of multiple switches of biologic in severe refractory RA. Methods: We enrolled 111 patients whose therapy with one anti-TNF agent had failed in this open-label observational study. These patients were all treated with a second biologic agent and 27 ultimately required treatment with a third. The response to the therapy and disease activity were assessed at 6 and 12 months after each switch. Results: The remission rates at 6 months were lower than previously reported and the initiation of a second biologic agent resulted in significant improvement at 12 months, including DAS remission in 36% of patients. The response in those receiving a third biologic was less pronounced, as might be expected in this relatively treatment-refractory population. In this group, only patients treated with tocilizumab had maintained remission at one year. Conclusion: Patients who do not respond to an anti-TNF agent often benefit from being switched to a second, or even third, biologic. Importantly, it may take longer than expected to fully assess the effectiveness of a second or third agent in patients with refractory disease
Future gravitational wave detectors: Phase noise investigation and magnetic noise mitigation strategies
No full textInternational audienceThe sensitivity of future gravitational wave (GW) detectors, such as the Einstein Telescope (ET), is constrained by quantum noise across the entire frequency range (10 Hz–10 kHz) and by magnetic noise at low frequencies (a few Hz to around 100 Hz). This article examines optimizing mechanisms to achieve efficient squeezing for reducing quantum noise, and also highlights the need to mitigate magnetic noise, through ongoing strategies
The hunt for environmental noise in Virgo during the third observing run
No full textAbstract: The first twenty years of operation of gravitational-wave interferometers have shown that these detectors are affected by physical disturbances from the surrounding environment. These are seismic, acoustic, or electromagnetic disturbances that are mainly produced by the experiment infrastructure itself. Ambient noise can limit the interferometer sensitivity or potentially generate transients of non-astrophysical origin. Between 1 April 2019 and 27 March 2020, the network of second generation interferometers-LIGO, Virgo and GEO-performed the third joined observing run, named O3, searching for gravitational signals from the deep universe. A thorough investigation has been done on each detector before and during data taking in order to optimize its sensitivity and duty cycle. In this paper, we first revisit typical sources of environmental noise and their coupling paths, and we then describe investigation methods and tools. Finally, we illustrate applications of these methods in the hunt for environmental noise at the Virgo interferometer during the O3 run and its preparation phase. In particular, we highlight investigation techniques that might be useful for the next observing runs and the future generation of terrestrial interferometers
Array analysis of seismic noise at the Sos Enattos mine, the Italian candidate site for the Einstein Telescope
No full textThe area surrounding the dismissed mine of Sos Enattos (Sardinia, Italy) is the Italian candidate site for hosting Einstein Telescope (ET), the third-generation gravitational wave (GW) observatory. One of the goals of ET is to extend the sensitivity down to frequencies well below those currently achieved by GW detectors, i.e. down to 2 Hz. In the bandwidth [1,10] Hz, the seismic noise of anthropogenic origin is expected to represent the major perturbation to the operation of the infrastructure, and the site that will host the future detector must fulfill stringent requirements on seismic disturbances. In this paper we describe the operation of a temporary, 15-element, seismic array deployed in close proximity to the mine. Signals of anthropogenic origin have a transient nature, and their spectra are characterized by a wide spectral lobe spanning the [3,20] Hz frequency interval. Superimposed to this wide lobe are narrow spectral peaks within the [3,8] Hz frequency range. Results from slowness analyses suggest that the origin of these peaks is related to vehicle traffic along the main road running east of the mine. Exploiting the correlation properties of seismic noise, we derive a dispersion curve for Rayleigh waves, which is then inverted for a shallow velocity structure down to depths of ≈≈ 150 m. This data, which is consistent with that derived from analysis of a quarry blast, provide a first assessment of the elastic properties of the rock materials at the site candidate to hosting ET
Characterizing the Sardinia candidate site for the Einstein telescope
No full textDue to its unique geophysical features and to the low density population of the area, Sos Enattos is a promising candidate site to host the Einstein Telescope (ET), the third-generation Gravitational Wave Observatory. The geophysical characterization of the Sos Enattos former mine, close to one of the proposed ET corners, started in 2010 with the deployment of seismic and environmental sensors underground. Since 2019 a new extensive array of seismometers, magnetometers and acoustic sensors have been installed in three stations along the underground tunnels, with one additional station at the surface. Beside a new geological survey over a wider area, two boreholes about 270 m deep each were excavated at the other two corners, determining the good quality of the drilled granite and orthogneiss rocks and the absence of significant thoroughgoing fault zones. These boreholes are instrumented with broadband seismometers that revealed an outstanding low level of vibrational noise in the low-frequency band of ET-LF (2-10Hz), significantly lower than the Peterson's NLNM and resulting among the quietest seismic stations in the world in that frequency band. The low seismic background and the reduced number of seismic glitches ensure that just a moderated Newtonian noise subtraction would be needed to achieve the ET target sensitivity. Geoelectrical and active seismic campaigns have been carried out to reveal the features of the subsurface, revealing the presence of small-sized fractured areas with limited water circulation. Finally, temporary arrays of seismometers, magnetometers and acoustic sensors are deployed in the area to study the local sources of environmental noise
