1,096 research outputs found
Evolution of the disc atmosphere in the X-ray binary MXB 1659-298, during its 2015-2017 outburst
We report on the evolution of the X-ray emission of the accreting neutron
star (NS) low mass X-ray binary (LMXB), MXB 1659-298, during its most recent
outburst in 2015-2017. We detected 60 absorption lines during the soft state
(of which 21 at more than 3 ), that disappeared in the hard state
(e.g., the Fe xxv and Fe xxvi lines). The absorbing plasma is at rest, likely
part of the accretion disc atmosphere. The bulk of the absorption features can
be reproduced by a high column density () of highly
ionised () plasma. Its disappearance during the
hard state is likely the consequence of a thermal photo-ionisation instability.
MXB 1659-298's continuum emission can be described by the sum of an absorbed
disk black body and its Comptonised emission, plus a black body component. The
observed spectral evolution with state is in line with that typically observed
in atoll and stellar mass black hole LMXB. The presence of a relativistic Fe
K disk-line is required during the soft state. We also tentatively
detect the Fe xxii doublet, whose ratio suggests an electron density of the
absorber of , hence, the absorber is likely located at
from the illuminating source, well inside the Compton and
outer disc radii. MXB 1659-298 is the third well monitored atoll LMXB
showcasing intense Fe xxv and Fe xxvi absorption during the soft state that
disappears during the hard state.Comment: MNRAS in pres
Probing variability patterns of the Fe K line complex in bright nearby AGNs
The unprecedented sensitivity of current X-ray telescopes allows for the
first time to address the issue of the Fe K line complex variability patterns
in bright, nearby AGNs. We examine XMM-Newton observations of the brightest
sources of the FERO sample of radio-quiet type 1 AGNs with the aim of
characterizing the temporal behaviour of Fe K complex features. A systematic
mapping of residual flux above and below the continuum in the 4-9 keV range is
performed in the time vs energy domain, with the purpose of identifying
interesting spectral features in the three energy bands: 5.4-6.1 keV, 6.1-6.8
keV and 6.8-7.2 keV, corresponding respectively to the redshifted, rest frame
and blueshifted or highly ionized Fe Kalpha line bands. The variability
significance is assessed by extracting light curves and comparing them with
MonteCarlo simulations. The time-averaged profile of the Fe K complex revealed
spectral complexity in several observations. Red- and blue-shifted components
(either in emission or absorption) were observed in 30 out of 72 observations,
with an average ~90 eV for emission and ~ -30 eV for absorption
features. We detected significant line variability (with confidence levels
ranging between 90% and 99.7%) within at least one of the above energy bands in
26 out of 72 observations on time scales of ~6-30 ks. Reliability of these
features has been carefully calculated using this sample and has been assessed
at ~3sigma confidence level. This work increases the currently scanty number of
detections of variable, energy shifted, Fe lines and confirms the reliability
of the claimed detections. We found that the distribution of detected features
is peaked at high variability significances in the red- and blue-shifted energy
bands, suggesting an origin in a relativistically modified accretion flow.Comment: Accepted for publication in Astronomy & Astrophysic
Bandgap widening and resonator mass reduction through wave locking
Elastic metamaterials made of locally resonant arrays have been developed as effective ways to create band gaps for elastic or acoustic travelling waves. They work by implementing stationary states in the structure that localise and partially reflect waves. A different, simpler, way of obtaining band gaps is using phononic crystals, where the generated band gaps come from the periodic reflection and phase cancellation of travelling waves. In this work a different metamaterial structure that generates band gaps by means of coupling two contra-propagating modes is reported. This metamaterial, as it will be shown numerically and experimentally, generates larger band gaps with lower added mass, providing benefits for lighter structures
Ultrasound imaging, a stethoscope for body composition assessment
Bone and muscle are two deeply interconnected organs and a strong relationship between them exists in their development and maintenance. The peak of both bone and muscle mass is achieved in early adulthood, followed by a progressive decline after the age of 40. The increase in life expectancy in developed countries resulted in an increase of degenerative diseases affecting the musculoskeletal system. Osteoporosis and sarcopenia represent a major cause of morbidity and mortality in the elderly population and are associated with a significant increase in healthcare costs. Several imaging techniques are currently available for the non-invasive investigation of bone and muscle mass and quality. Conventional radiology, dual energy X-ray absorptiometry (DXA), computed tomography (CT), magnetic resonance imaging (MRI) and ultrasound often play a complementary role in the study of osteoporosis and sarcopenia, depicting different aspects of the same pathology. This paper presents the different imaging modalities currently used for the investigation of bone and muscle mass and quality in osteoporosis and sarcopenia with special emphasis on the clinical applications and limitations of each technique and with the intent to provide interesting insights into recent advances in the field of conventional imaging, novel high-resolution techniques and fracture risk
Graded elastic metasurface for enhanced energy harvesting
In elastic wave systems, combining the powerful concepts of resonance and spatial grading within structured surface arrays enable resonant metasurfaces to exhibit broadband wave trapping, mode conversion from surface (Rayleigh) waves to bulk (shear) waves, and spatial frequency selection. Devices built around these concepts allow for precise control of surface waves, often with structures that are subwavelength, and utilise Rainbow trapping that separates the signal spatially by frequency. Rainbow trapping yields large amplifications of displacement at the resonator positions where each frequency component accumulates. We investigate whether this amplification, and the associated control, can be used to create energy harvesting devices; the potential advantages and disadvantages of using graded resonant devices as energy harvesters is considered. We concentrate upon elastic plate models for which the A0 mode dominates, and take advantage of the large displacement amplitudes in graded resonant arrays of rods, to design innovative metasurfaces that trap waves for enhanced piezoelectric energy harvesting. Numerical simulation allows us to identify the advantages of such graded metasurface devices and quantify its efficiency, we also develop accurate models of the phenomena and extend our analysis to that of an elastic half-space and Rayleigh surface waves
Lessons to be Learnt from Real-World Studies on Immune-Related Adverse Events with Checkpoint Inhibitors: A Clinical Perspective from Pharmacovigilance
The advent of immune checkpoint inhibitors (ICIs) caused a paradigm shift both in drug development and clinical practice; however, by virtue of their mechanism of action, the excessively activated immune system results in a multitude of off-target toxicities, the so-called immune-related adverse events (irAEs), requiring new skills for timely diagnosis and a multidisciplinary approach to successfully manage the patients. In the recent past, a plethora of large-scale pharmacovigilance analyses have characterized various irAEs in terms of spectrum and clinical features in the real world. This review aims to summarize and critically appraise the current landscape of pharmacovigilance studies, thus deriving take-home messages for oncologists. A brief primer to study design, conduction, and data interpretation is also offered. As of February 2020, 30 real-world postmarketing studies have characterized multiple irAEs through international spontaneous reporting systems, namely WHO Vigibase and the US FDA Adverse Event Reporting System. The majority of studies investigated a single irAE and provided new epidemiological evidence about class-specific patterns of irAEs (i.e. anti-cytotoxic T-lymphocyte antigen 4 [CTLA-4] versus anti-programmed cell death 1 [PD-1] receptor, and its ligand [PD-L1]), kinetics of appearance, co-occurrences (overlap) among irAEs, and fatality rate. Oncologists should be aware of both strengths and limitations of these pharmacovigilance analyses, especially in terms of data interpretation. Optimal management (including rechallenge), predictivity of irAEs (as potential biomarkers of effectiveness), and comparative safety of ICIs (also in terms of combination regimens) represent key research priorities for next-generation real-world studies
Aspetti clinici e medico-legali nella terapia infiltrativa
The usefulness of local infiltrative treatment is recognized in most guidelines: it consists in the instillation of drugs (steroids, local anesthetics or hyaluronic acid) directly at the site of illness (intra- or periarticular or in soft tissues). Treatment indications must be documented in a clinical report or certification including objective clinical data. Infiltration is an invasive procedure that involves possible side effects and complications. Therefore, the patient must receive from the doctor all the information necessary to grant a valid consent to treatment. During the informative interview, which can be accompanied (but not replaced) by the delivery of a short information form to the patient, the doctor must explain, in a comprehensible way for the single patient, diagnosis, type of treatment proposed, its modalities of execution, potential benefits and risks, possible complications and alternative therapies, behavior that the patient has to observe during the treatment process. The law 219/2017 expressly stated the necessity of the acquisition of consent in written form. In this paper, samples of informative and consent forms for infiltrative therapy are proposed: they can represent a useful tool for both professionals and patients
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