1,442 research outputs found
The Equilibrium Photoionized Absorber in 3C351
We present two ROSAT PSPC observations of the radio-loud, lobe-dominated
quasar 3C 351, which shows an `ionized absorber' in its X-ray spectrum. The
factor 1.7 change in flux in the 2~years between the observations allows
a test of models for this ionized absorber.
The absorption feature at ~0.7 keV (quasar frame) is present in both spectra
but with a lower optical depth when the source intensity - and hence the
ionizing flux at the absorber - is higher, in accordance with a simple,
single-zone, equilibrium photoionization model. Detailed modeling confirms this
agrement quantitatively. The maximum response time of 2 years allows us to
limit the gas density: n_e > 2 x 10^4 cm^{-3}; and the distance of the ionized
gas from the central source R < 19 pc. This produces a strong test for a
photoionized absorber in 3C~351: a factor 2 flux change in ~1 week in this
source must show non-equilibrium effects in the ionized absorber.Comment: 10 pages, 3 figures, accepted by Ap
Real-Time Analysis sensitivity evaluation of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA), the new generation very high-energy gamma-ray observatory, will improve the flux sensitivity of the current Cherenkov telescopes by an order of magnitude over a continuous range from about 10 GeV to above 100 TeV. With tens of telescopes distributed in the Northern and Southern hemispheres, the large effective area and field of view coupled with the fast pointing capability make CTA a crucial instrument for the detection and understanding of the physics of transient, short-timescale variability phenomena (e.g. Gamma-Ray Bursts, Active Galactic Nuclei, gamma-ray binaries, serendipitous sources). The key CTA system for the fast identification of flaring events is the Real-Time Analysis (RTA) pipeline, a science alert system that will automatically detect and generate science alerts with a maximum latency of 30 seconds with respect to the triggering event collection and ensure fast communication to/from the astrophysics community. According to the CTA design requirements, the RTA search for a true transient event should be performed on multiple time scales (from minutes to hours) with a sensitivity not worse than three times the nominal CTA sensitivity. Given the CTA requirement constraints on the RTA efficiency and the fast response ability demanded by the transient science, we perform a preliminary evaluation of the RTA sensitivity as a function of the CTA high-level technical performance (e.g. effective area, point spread function) and the observing time. This preliminary approach allows the exploration of the complex parameter space defined by the scientific and technological requirements, with the aim of defining the feasibility range of the input parameters and the minimum background rejection capability of the RTA pipeline
In vitro and in vivo study of a novel biodegradable synthetic conduit for injured peripheral nerves
In case of peripheral nerve injury (PNI) with wide substance-loss, surgical reconstruction is still a challenge. Bridging the gap by autologous sensory nerves as grafts is the current standard; nevertheless, the related issues have prompted the research towards the development of effective artificial synthetic/biological nerve conduits (NCs). Here, we manufactured a novel NC using oxidized polyvinyl alcohol (OxPVA) that is a biodegradable cryogel recently patented by our group [1]. Thus, its characteristics were compared with neat polyvinyl alcohol (PVA) and silk-fibroin (SF) NCs through in vitro/in vivo analysis. Considering in vitro studies, a morphological characterization was performed by Scanning Electron Microscopy (SEM). Thereafter, cell adhesion and proliferation of a Schwann-cell line (SH-SY5Y) were evaluated by SEM and MTT assay. Regarding in vivo tests, the NCs were implanted into the surgical injured sciatic nerve (gap: 5 mm) of Sprague-Dawley rats, and the functional recovery was assessed after 12-weeks. The NCs were then processed for histological, immunohistochemical (anti-CD3; -β-tubulin; -S100) and Transmission Electron Microscopy (TEM) analyses. In particular, morphometric analyses (section area, total number and density of nerve fibers) were performed at the level of proximal, central and distal portions with respect to NC. In vitro results by SEM showed that PVA and SF supports have a smoother surface than OxPVA scaffolds. Moreover, unlike SF scaffolds, PVA-based ones do not support SH-SY5Y adhesion and proliferation. Regarding the in vivo study, all animals showed a functional recovery with normal walk, even though only animals implanted with PVA and SF NCs sometimes showed spasms while walking. On the contrary, animals implanted with OxPVA NCs exhibited a normal movement. Anti-CD3 immunohistochemistry assessed the absence of severe inflammatory reactions in all the grafts. A strong positive immunoreaction for β-tubulin and S100 demonstrated the good regeneration of nervous fibers. TEM highlighted regeneration of myelinated/un-myelinated axons and Schwann cells in all the grafts. However, morphometric analysis demonstrated that OxPVA assure a better outcome in nerve regeneration in terms of total number of nerve fibers. Our results sustain the potential of OxPVA for the development of NCs useful for PNI with substance loss with the advantage of biodegradation
Effectiveness and tolerability of chlormethine gel for the management of mycosis fungoides: a multicenter real-life evaluation
BackgroundTopical chlormethine (CL) is recommended as a first-line treatment for early-stage mycosis fungoides (MF) and in 2017, the European Medicines Agency approved the CL gel formulation to treat adult patients. More recently, to increase patient compliance and adherence, clinicians have developed flexible protocols that allow the concomitant use of CL gel with topical corticosteroids in daily practice regimens. Therefore, sharing real-life data on CL gel use and side effects management may help improve the use of this agent.ObjectivesTo expand knowledge about the actual use of CL gel in patients with MF, the present study assessed the improvement of MF skin lesions after CL gel treatment and provided information on the management of cutaneous adverse events (AEs) in a real-life setting.MethodsThis was an Italian retrospective study conducted among six dermatology referral centers. Patients ≥18 years affected by MF and in treatment with CL gel (160 µ/g), alone or in combination according to routine clinical practice, between December 2019 and December 2021 were considered. The study’s primary aim was to evaluate the effectiveness of CL gel in terms of overall response rate (ORR) after 3 months of treatment.ResultsA total of 79 patients (61% male) with different stages of MF (84% early stage) were included. CL gel was prescribed mainly in association with topical corticosteroids (66% of patients). ORR after 3 months of treatment was 42%, with no differences between early- and advanced-stage MF. Response rates improved over time up to 97% after 18 months of treatment. Overall, 66 AEs were reported in 67% of patients; most were hyperpigmentation (45%) and irritant contact dermatitis (37%). Six AEs led to treatment discontinuation, and five out of six (83%) patients who reported these events resumed treatment after interruption. No AEs were classified as severe.ConclusionsOur observations support the use of CL gel in patients with early- and advanced-stage MF, making it a valuable treatment option
The On-Site Analysis of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) observatory will be one of the largest
ground-based very high-energy gamma-ray observatories. The On-Site Analysis
will be the first CTA scientific analysis of data acquired from the array of
telescopes, in both northern and southern sites. The On-Site Analysis will have
two pipelines: the Level-A pipeline (also known as Real-Time Analysis, RTA) and
the level-B one. The RTA performs data quality monitoring and must be able to
issue automated alerts on variable and transient astrophysical sources within
30 seconds from the last acquired Cherenkov event that contributes to the
alert, with a sensitivity not worse than the one achieved by the final pipeline
by more than a factor of 3. The Level-B Analysis has a better sensitivity (not
be worse than the final one by a factor of 2) and the results should be
available within 10 hours from the acquisition of the data: for this reason
this analysis could be performed at the end of an observation or next morning.
The latency (in particular for the RTA) and the sensitivity requirements are
challenging because of the large data rate, a few GByte/s. The remote
connection to the CTA candidate site with a rather limited network bandwidth
makes the issue of the exported data size extremely critical and prevents any
kind of processing in real-time of the data outside the site of the telescopes.
For these reasons the analysis will be performed on-site with infrastructures
co-located with the telescopes, with limited electrical power availability and
with a reduced possibility of human intervention. This means, for example, that
the on-site hardware infrastructure should have low-power consumption. A
substantial effort towards the optimization of high-throughput computing
service is envisioned to provide hardware and software solutions with
high-throughput, low-power consumption at a low-cost.Comment: In Proceedings of the 34th International Cosmic Ray Conference
(ICRC2015), The Hague, The Netherlands. All CTA contributions at
arXiv:1508.0589
Cluster di Calcolo di OAS-Bologna e Software Scientifico disponibile
All’interno dell’ Osservatorio di Astrofisica e Scienza dello Spazio di Bologna (OAS), da sempre abbiamo avuto la necessità di strumenti di calcolo potenti e condivisi su cui gli scienziati possano svolgere le elaborazioni sui dati scientifici di Progetti e Missioni.
Il Cluster OAS nasce proprio per soddisfare questa esigenza ed è ospitato nel Centro di Calcolo del plesso OAS presso il CNR di Bologna. Tutti gli afferenti a OAS possono chiedere di essere registrati nel sistema di autenticazione LDAP del Cluster e in questo modo accedere via Internet ai nodi di login da dove possono sottomettere le loro elaborazioni.
Ci sono due modalità di usare il cluster: quella interattiva e quella batch più classica per un Cluster. L’accesso interattivo consente di lanciare in tempo reale le elaborazioni anche in maniera grafica tramite opportuni programmi si console virtuale, questo tipo di elaborazione viene svolta direttamente nei nodi di login. La modalità batch sfrutta il meccanismo a code, slurm, per sottomettere i lavori in maniera organizzata ai più potenti nodi di calcolo che non sono direttamente utilizzabili dagli utenti.
Il cluster inoltre fornisce spazio di archiviazione condiviso organizzato in HOME per i dati personali degli utenti, DATA per i risultati delle elaborazioni PROGRAMMI per la memorizzazione dei moduli di elaborazione e LUSTRE per il calcolo parallelo.
I vantaggi di avere un Cluster sono che gli utenti trovano i programmi e compilatori di cui necessitano già installati nelle principali versioni e hanno a disposizione una buona potenza di calcolo e spazio di storage per poter lavorare molto più agevolmente rispetto ai propri computer personali.
Il Cluster OAS non ha una potenza paragonabile ai grandi Cluster Commerciali e di Ricerca, ma essendo ritagliato sulle esigenze degli afferenti a OAS risponde bene alle esigenze dell'istituto e può servire come Nave Scuola per poter poi accedere a strutture più grandi qualora fosse necessario.
Nel documento saranno illustrate nel dettaglio le caratteristiche Hardware e Software del Cluster, compresi tutti i principali Software scientifici installati di cui si spiega brevemente l’utilizzo
A prototype for the real-time analysis of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) observatory will be one of the biggest ground-based very-high-energy (VHE) γ- ray observatory. CTA will achieve a factor of 10 improvement in sensitivity from some tens of GeV to beyond 100 TeV with respect to existing telescopes. The CTA observatory will be capable of issuing alerts on variable and transient sources to maximize the scientific return. To capture these phenomena during their evolution and for effective communication to the astrophysical community, speed is crucial. This requires a system with a reliable automated trigger that can issue alerts immediately upon detection of γ-ray flares. This will be accomplished by means of a Real-Time Analysis (RTA) pipeline, a key system of the CTA observatory. The latency and sensitivity requirements of the alarm system impose a challenge because of the anticipated large data rate, between 0.5 and 8 GB/s. As a consequence, substantial efforts toward the optimization of highthroughput computing service are envisioned. For these reasons our working group has started the development of a prototype of the Real-Time Analysis pipeline. The main goals of this prototype are to test: (i) a set of frameworks and design patterns useful for the inter-process communication between software processes running on memory; (ii) the sustainability of the foreseen CTA data rate in terms of data throughput with different hardware (e.g. accelerators) and software configurations, (iii) the reuse of nonreal- time algorithms or how much we need to simplify algorithms to be compliant with CTA requirements, (iv) interface issues between the different CTA systems. In this work we focus on goals (i) and (ii)
The On-Site Analysis of the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) observatory will be one of the largest ground-based very high-energy gamma-ray observatories. The On-Site Analysis will be the first CTA scientific analysis of data acquired from the array of telescopes, in both northern and southern sites. The On-Site Analysis will have two pipelines: the Level-A pipeline (also known as Real-Time Analysis, RTA) and the level-B one. The RTA performs data quality monitoring and must be able to issue automated alerts on variable and transient astrophysical sources within 30 seconds from the last acquired Cherenkov event that contributes to the alert, with a sensitivity not worse than the one achieved by the final pipeline by more than a factor of 3. The Level-B Analysis has a better sensitivity (not be worse than the final one by a factor of 2) and the results should be available within 10 hours from the acquisition of the data: for this reason this analysis could be performed at the end of an observation or next morning. The latency (in particular for the RTA) and the sensitivity requirements are challenging because of the large data rate, a few GByte/s. The remote connection to the CTA candidate site with a rather limited network bandwidth makes the issue of the exported data size extremely critical and prevents any kind of processing in real-time of the data outside the site of the telescopes. For these reasons the analysis will be performed on-site with infrastructures co-located with the telescopes, with limited electrical power availability and with a reduced possibility of human intervention. This means, for example, that the on-site hardware infrastructure should have low-power consumption. A substantial effort towards the optimization of high-throughput computing service is envisioned to provide hardware and software solutions with high-throughput, low-power consumption at a low-cost
Differential cross section measurements for the production of a W boson in association with jets in proton–proton collisions at √s = 7 TeV
Measurements are reported of differential cross sections for the production of a W boson, which decays into a muon and a neutrino, in association with jets, as a function of several variables, including the transverse momenta (pT) and pseudorapidities of the four leading jets, the scalar sum of jet transverse momenta (HT), and the difference in azimuthal angle between the directions of each jet and the muon. The data sample of pp collisions at a centre-of-mass energy of 7 TeV was collected with the CMS detector at the LHC and corresponds to an integrated luminosity of 5.0 fb[superscript −1]. The measured cross sections are compared to predictions from Monte Carlo generators, MadGraph + pythia and sherpa, and to next-to-leading-order calculations from BlackHat + sherpa. The differential cross sections are found to be in agreement with the predictions, apart from the pT distributions of the leading jets at high pT values, the distributions of the HT at high-HT and low jet multiplicity, and the distribution of the difference in azimuthal angle between the leading jet and the muon at low values.United States. Dept. of EnergyNational Science Foundation (U.S.)Alfred P. Sloan Foundatio
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