683 research outputs found
Evidence for Dynamically Driven Formation of the GW170817 Neutron Star Binary in NGC 4993
We present a study of NGC 4993, the host galaxy of the GW170817 gravitational-wave event, the GRB 170817A short gamma-ray burst (sGRB), and the AT 2017gfo kilonova. We use Dark Energy Camera imaging, AAT spectra, and publicly available data, relating our findings to binary neutron star (BNS) formation scenarios and merger delay timescales. NGC 4993 is a nearby early-type galaxy, with an i-band Sérsic index n = 4.0 and low asymmetry (A = 0.04 ± 0.01). These properties are unusual for sGRB hosts. However, NGC 4993 presents shell-like structures and dust lanes indicative of a recent galaxy merger, with the optical transient located close to a shell. We constrain the star formation history (SFH) of the galaxy assuming that the galaxy merger produced a star formation burst, but find little to no ongoing star formation in either spatially resolved broadband SED or spectral fitting. We use the best-fit SFH to estimate the BNS merger rate in this type of galaxy, as R^(gal)_(NSM) = 5.7^(+0.57)_(-3.3) x 10^(-6) yr^(-1). If star formation is the only considered BNS formation scenario, the expected number of BNS mergers from early-type galaxies detectable with LIGO during its first two observing seasons is 0.038^(+0.004)_(-0.022), as opposed to ~0.5 from all galaxy types. Hypothesizing that the binary formed due to dynamical interactions during the galaxy merger, the subsequent time elapsed can constrain the delay time of the BNS coalescence. By using velocity dispersion estimates and the position of the shells, we find that the galaxy merger occurred t_(mer) ≾ 200 Myr prior to the BNS coalescence
Collecting Channel State Information in Wi-Fi Access Points for IoT Forensics
The Internet of Things (IoT) has boomed in recent years, with an ever-growing number of connected devices and a corresponding exponential increase in network traffic. As a result, IoT devices have become potential witnesses of the surrounding environment and people living in it, creating a vast new source of forensic evidence. To address this need, a new field called IoT Forensics has emerged. In this paper, we present CSI Sniffer, a tool that integrates the collection and management of Channel State Information (CSI) in WiFi Access Points. CSI is a physical layer indicator that enables human sensing, including occupancy monitoring and activity recognition. After a description of the tool architecture and implementation, we demonstrate its capabilities through two application scenarios that use binary classification techniques to classify user behavior based on CSI features extracted from IoT traffic. Our results show that the proposed tool can enhance the capabilities of forensic investigations by providing additional sources of evidence. Wi-Fi Access Points integrated with CSI Sniffer can be used by ISP or network managers to facilitate the collection of information from IoT devices and the surrounding environment. We conclude the work by analyzing the storage requirements of CSI sample collection and discussing the impact of lossy compression techniques on classification performance
Evidence for Dynamically Driven Formation of the GW170817 Neutron Star Binary in NGC 4993
We present a study of NGC 4993, the host galaxy of the GW170817 gravitational-wave event, the GRB 170817A short gamma-ray burst (sGRB), and the AT 2017gfo kilonova. We use Dark Energy Camera imaging, AAT spectra, and publicly available data, relating our findings to binary neutron star (BNS) formation scenarios and merger delay timescales. NGC 4993 is a nearby early-type galaxy, with an i-band Sérsic index n = 4.0 and low asymmetry (A = 0.04 ± 0.01). These properties are unusual for sGRB hosts. However, NGC 4993 presents shell-like structures and dust lanes indicative of a recent galaxy merger, with the optical transient located close to a shell. We constrain the star formation history (SFH) of the galaxy assuming that the galaxy merger produced a star formation burst, but find little to no ongoing star formation in either spatially resolved broadband SED or spectral fitting. We use the best-fit SFH to estimate the BNS merger rate in this type of galaxy, as R^(gal)_(NSM) = 5.7^(+0.57)_(-3.3) x 10^(-6) yr^(-1). If star formation is the only considered BNS formation scenario, the expected number of BNS mergers from early-type galaxies detectable with LIGO during its first two observing seasons is 0.038^(+0.004)_(-0.022), as opposed to ~0.5 from all galaxy types. Hypothesizing that the binary formed due to dynamical interactions during the galaxy merger, the subsequent time elapsed can constrain the delay time of the BNS coalescence. By using velocity dispersion estimates and the position of the shells, we find that the galaxy merger occurred t_(mer) ≾ 200 Myr prior to the BNS coalescence
Sarcopenia and vitamin d deficiency in patients with crohn’s disease: Pathological conditions that should be linked together
Sarcopenia is a prevalent condition in patients with Crohn’s disease (CD), representing an independent predictor factor for the development of major postoperative complications. Thus, a proper assessment of the muscle strength, by using different validated tools, should be deemed an important step of the clinical management of these patients. Patients with CD are frequently malnourished, presenting a high prevalence of different macro-and micro-nutrient deficiencies, including that of vitamin D. The available published studies indicate that vitamin D is involved in the regulation of proliferation, differentiation, and regeneration of muscle cells. The relationship between vitamin D deficiency and sarcopenia has been extensively studied in other populations, with interesting evidence in regards to a potential role of vitamin D supplementation as a means to prevent and treat sarcopenia. The aim of this review was to find studies that linked together these pathological conditions
Relationship between Muscle Mass, Bone Density and Vascular Calcifications in Elderly People with SARS-CoV-2 Pneumonia
Background: Little is known about the changes in organs and tissues that may make elder patients more vulnerable to acute stressors such as SARS-CoV-2 infection.
Methods: In 80 consecutive elderly patients with SARS-CoV-2 infection, we evaluated the association between the descending thoracic aorta calcium score, L1 bone density and T12 skeletal muscle density measured on the same scan by high-resolution computed tomography.
Results: At median regression, the ln-transformed DTA calcium score was inversely associated with L1 bone density (-0.02, 95%CI -0.04 to -0.01 ln-Agatston units for an increase of 1 HU) and with T12 muscle density (-0.03, -0.06 to -0.001 ln-Agatston units for an increase of 1 HU). At penalized logistic regression, an increase of 1 ln-Agatston unit of DTA calcium score was associated with an OR of death of 1.480 (1.022 to 2.145), one of 1 HU of bone density with an OR of 0.981 (0.966 to 0.996) and one of 1 HU of muscle density with an OR of 0.973 (0.948 to 0.999). These relationships disappeared after correction for age and age was the stronger predictor of body composition and death.
Conclusions: Age has a big effect on the relationship between vascular calcifications, L1 bone density and T12 muscle density and on their relationship with the odds of dying.
Keywords: SARS-CoV-2; bone density; computed tomography; diagnostic imaging; frailty; mortality; muscle mass; vascular calcifications
Low haemoglobin level predicts early hospital readmission in patients with cirrhosis and acute decompensation
Background & Aims: Patients with decompensated cirrhosis present frequent hospitalisations with a relevant clinical and socio-economic impact. This study aims to characterise unscheduled readmissions up to 1-year follow-up and identify predictors of 30-day readmission after an index hospitalisation for acute decompensation (AD). Methods: We performed a secondary analysis of a prospectively collected cohort of patients admitted for AD. Laboratory and clinical data at admission and at discharge were collected. Timing and causes of unscheduled readmissions and mortality were recorded up to 1 year. Results: A total of 329 patients with AD were included in the analysis. Acute-on-chronic liver failure was diagnosed in 19% of patients at admission or developed in an additional 9% of patients during the index hospitalisation. During the 1-year follow-up, 182 patients (55%) were rehospitalised and 98 (30%) more than once. The most frequent causes of readmission were hepatic encephalopathy (36%), ascites (22%), and infection (21%). Cumulative incidence of readmission was 20% at 30 days, 39% at 90 days, and 63% at 1 year. Fifty-four patients were readmitted for emergent liver-related causes within 30 days. Early readmission was associated with a higher 1-year mortality (47 vs. 32%, p = 0.037). Multivariable Cox regression analysis showed that haemoglobin (Hb) ≤8.7 g/dl (hazard ratio 2.63 [95% CI 1.38–5.02], p = 0.003) and model for end-stage liver disease-sodium score (MELD-Na) >16 at discharge (hazard ratio 2.23 [95% CI 1.27–3.93], p = 0.005), were independent predictors of early readmission. In patients with MELD-Na >16 at discharge, the presence of Hb ≤8.7 g/dl doubles the risk of early rehospitalisation (44% vs. 22%, p = 0.02). Conclusion: Besides MELD-Na, a low Hb level (Hb ≤8.7 g/dl) at discharge emerged as a new risk factor for early readmission, contributing to identification of patients who require closer surveillance after discharge. Impact and Implications: Patients with decompensated cirrhosis face frequent hospitalisations. In the present study, type and causes of readmissions were analysed during 1-year follow-up in patients discharged after the index hospitalisation for an acute decompensation of the disease. Early (30-day) liver-related readmission was associated with higher 1-year mortality. The model for end-stage liver disease-sodium score and low haemoglobin at discharge were identified as independent risk factors for early readmissions. Haemoglobin emerged as a new easy-to-use parameter associated with early readmission warranting further investigation
Comparative Assessment of the Structural Features of Originator Recombinant Human Follitropin Alfa Versus Recombinant Human Follitropin Alfa Biosimilar Preparations Approved in Non-European Regions
Although the full primary structures of the alfa and beta subunits of reference r-hFSH-alfa and its biosimilars are identical, cell context-dependent differences in the expressing cell lines and manufacturing process can lead to variations in glycosylation profiles. In the present study, we compared the structural features of reference r-hFSH-alfa with those of five biosimilar preparations approved in different global regions outside Europe (Primapur®, Jin Sai Heng®, Follitrope®, Folisurge®, and Corneumon®) with respect to glycosylation, macro- and microheterogeneity, and other post-translational modifications and higher order structure. The mean proportion of N-glycosylation-site occupancy was highest in reference r-hFSH-alfa, decreasing sequentially in Primapur, Jin Sai Heng, Corneumon, Follisurge and Follitrope, respectively. The level of antennarity showed slightly higher complexity in Corneumon, Primapur and Follitrope versus reference r-hFSH-alfa, whereas Jin Sai Heng and Folisurge were aligned with reference r-hFSH-alfa across all N-glycosylation sites. Sialylation level was higher in Corneumon and Follitrope, but small differences were detected in other biosimilar preparations compared with reference r-hFSH-alfa. Jin Sai Heng showed higher levels of N-glyconeuramic acid than the other preparations. Minor differences in oxidation levels were seen among the different products. Therefore, in summary, we identified var ious differences in N-glycosylation occupancy, antennarity, sialylation and oxidation between reference r-hFSH-alfa and the biosimilar preparations analyzed
Chemical Abundance Analysis of Tucana III, the Second -process Enhanced Ultra-Faint Dwarf Galaxy
We present a chemical abundance analysis of four additional confirmed member
stars of Tucana III, a Milky Way satellite galaxy candidate in the process of
being tidally disrupted as it is accreted by the Galaxy. Two of these stars are
centrally located in the core of the galaxy while the other two stars are
located in the eastern and western tidal tails. The four stars have chemical
abundance patterns consistent with the one previously studied star in Tucana
III: they are moderately enhanced in -process elements, i.e. they have
0.4 dex. The non-neutron-capture elements generally
follow trends seen in other dwarf galaxies, including a metallicity range of
0.44 dex and the expected trend in -elements, i.e., the lower
metallicity stars have higher Ca and Ti abundance. Overall, the chemical
abundance patterns of these stars suggest that Tucana III was an ultra-faint
dwarf galaxy, and not a globular cluster, before being tidally disturbed. As is
the case for the one other galaxy dominated by -process enhanced stars,
Reticulum II, Tucana III's stellar chemical abundances are consistent with
pollution from ejecta produced by a binary neutron star merger, although a
different -process element or dilution gas mass is required to explain the
abundances in these two galaxies if a neutron star merger is the sole source of
-process enhancement.Comment: 18 pages, 10 figures; accepted by Ap
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