Probing Turbulence in the Coma Galaxy Cluster

Spatially-resolved gas pressure maps of the Coma galaxy cluster are obtained from a mosaic of XMM-Newton observations in the scale range between a resolution of 20 kpc and an extent of 2.8 Mpc. A Fourier analysis of the data reveals the presence of a scale-invariant pressure fluctuation spectrum in the range between 40 and 90 kpc and is found to be well described by a projected Kolmogorov/Oboukhov-type turbulence spectrum. Deprojection and integration of the spectrum yields the lower limit of $\sim 10$ percent of the total intracluster medium pressure in turbulent form. The results also provide observational constraints on the viscosity of the gas.Comment: 12 pages, 13 figures (low resolution), version accepted by Astron. Astrophy

Perfusion SPECT in patients with suspected pulmonary embolism.

PURPOSE: Ventilation/perfusion tomography (V/PSPECT), with new interpretation criteria and newer tracers for ventilation imaging, has markedly improved the diagnostic yield in acute pulmonary embolism (PE). Here, we evaluated the diagnostic performance of perfusion SPECT (PSPECT) without ventilation imaging. METHODS: We studied 152 patients with clinically suspected PE who had been examined with both V/PSPECT and multidetector computed tomographic angiography (MD-CTA). The diagnosis or exclusion of PE was decided by the referring clinician based on both the V/PSPECT and/or MD-CTA findings in combination with the clinical findings. PSPECT images were retrospectively examined by a physician with experience in the interpretation of planar perfusion scans who was blinded to clinical, V/PSPECT and MD-CTA data. PSPECT images were interpreted without the aid of chest radiography. All the patients who were deemed to have PE were given anticoagulant therapy. RESULTS: Of the 152 patients, 59 (39 %) received a final diagnosis of PE, and 19 (32 %) had associated cardiopulmonary diseases such as pneumonia, COPD, or left heart failure. PSPECT correctly identified 53 (90 %) of the 59 patients with PE. The specificity was 88 of 93 (95 %). None of the PSPECT images was rated nondiagnostic. PSPECT yielded an overall diagnostic accuracy of 93 % (95 % confidence interval, CI, 87-96 %). At the observed PE prevalence of 39 %, the positive and negative predictive values of PSPECT were 91 % (95 % CI, 80-97 %) and 94 % (95 % CI, 86-97 %), respectively. CONCLUSION: In managing critically ill patients, PSPECT might be a valid alternative to V/PSPECT or MD-CTA since it was able to identify most patients with PE with a low false-positive rate and no inconclusive results

Extreme cosmic ray dominated regions: a new paradigm for high star formation density events in the Universe

We examine in detail the recent proposal that extreme cosmic ray dominated regions (CRDRs) characterize the interstellar medium of galaxies during events of high-density star formation, fundamentally altering its initial conditions (Papadopoulos 2010). Solving the coupled chemical and thermal state equations for dense UV-shielded gas reveals that the large CR energy densities in such systems [UCR ∼ few × (103-104) UCR, Gal] will indeed raise the minimum temperature of this phase (where the initial conditions of star formation are set) from ∼10 K (as in the Milky Way) to ∼50-100 K. Moreover in such extreme CRDRs the gas temperature remains fully decoupled from that of the dust, with Tkin≫Tdust, even at high densities [n(H2) ∼ 105-106 cm−3], quite unlike CRDRs in the Milky Way where Tk∼Tdust when n(H2) ≳ 105 cm−3. These dramatically different star formation initial conditions will (i) boost the Jeans mass of UV-shielded gas regions by factors of ∼10-100 with respect to those in quiescent or less extreme star-forming systems and (ii) ‘erase' the so-called inflection point of the effective equation of state of molecular gas. Both these effects occur across the entire density range of typical molecular clouds, and may represent a new paradigm for all high-density star formation in the Universe, with CRs as the key driving mechanism, operating efficiently even in the high dust extinction environments of compact extreme starbursts. The characteristic mass of young stars will be boosted as a result, naturally yielding a top-heavy stellar initial mass function (IMF) and a bimodal star formation mode (with the occurrence of extreme CRDRs setting the branching point). Such CRDRs will be present in Ultra-Luminous Infrared Galaxies (ULIRGs) and merger-driven gas-rich starbursts across the Universe where large amounts of molecular gas rapidly dissipate towards compact disc configurations where they fuel intense starbursts. In hierarchical galaxy formation models, CR-controlled star formation initial conditions lend a physical basis for the currently postulated bimodal IMF in merger/starburst versus quiescent/disc star-forming environments, while naturally making the integrated galactic IMFs a function of the star formation history of galaxie

On the Exchange of Kinetic and Magnetic Energy Between Clouds and the Interstellar Medium

We investigate, through 2D MHD numerical simulations, the interaction of a uniform magnetic field oblique to a moving interstellar cloud. In particular we explore the transformation of cloud kinetic energy into magnetic energy as a result of field line stretching. Some previous simulations have emphasized the possible dynamical importance of a ``magnetic shield'' formed around clouds when the magnetic field is perpendicular to the cloud motion (Jones et al. 1996, Miniati et al. 1998). It was not clear, however, how dependent those findings were to the assumed field configuration and cloud properties. To expand our understanding of this effect, we examine several new cases by varing the magnetic field orientation angle with respect to the cloud motion (\theta), the cloud-background density contrast, and the cloud Mach number. We show that in 2D and with \theta large enough, the magnetic field tension can become dominant in the dynamics of the motion of high density contrast, low Mach number clouds. In such cases a significant fraction of cloud kinetic energy can be transformed into magnetic energy with the magnetic pressure at the cloud nose exceeding the ram pressure of the impinging flow. We derive a characteristic timescale for this process of energy ``conversion''. We find also that unless the cloud motion is highly aligned to the magnetic field, reconnection through tearing mode instabilities in the cloud wake limit the formation of a strong flux rope feature following the cloud. Finally we attempt to interpret some observational properties of the magnetic field in view of our results.Comment: 24 pages in aaspp4 Latex and 7 figures. Accepted for publication in The Astrophysical Journa

Strong magnetic fields in normal galaxies at high redshifts

The origin and growth of magnetic fields in galaxies is still something of an enigma. It is generally assumed that seed fields are amplified over time through the dynamo effect, but there are few constraints on the timescale. It has recently been demonstrated that field strengths as traced by rotation measures of distant quasars are comparable to those seen today, but it was unclear whether the high fields were in the exotic environments of the quasars themselves or distributed along the line of sight. Here we demonstrate that the quasars with strong MgII absorption lines are unambiguously associated with larger rotation measures. Since MgII absorption occurs in the haloes of normal galaxies along the sightline to the quasars, this association requires that organized fields of surprisingly high strength are associated with normal galaxies when the Universe was only about one-third of its present age.Comment: 11 pages, 2 figures, Letter to Nature, accepted. Final version available at http://www.nature.com/nature/journal/v454/n7202/abs/nature07105.htm

Angular Anisotropies in the Cosmic Gamma-ray Background as a Probe of its Origin

Notwithstanding the advent of the Gamma-ray Large Area Telescope, theoretical models predict that a significant fraction of the cosmic gamma-ray background (CGB), at the level of 20% of the currently measured value, will remain unresolved. The angular power spectrum of intensity fluctuations of the CGB contains information on its origin. We show that probing the latter from a few tens of arcmin to several degree scales, together with complementary GLAST observations of gamma-ray emission from galaxy clusters and the blazars luminosity function, can discriminate between a background that originates from unresolved blazars or cosmic rays accelerated at structure formation shocks.Comment: 4 pages, 3 figures. Replaced to match version accepted for publication in Astrophys. J. Let

Integrated HTA and FMECA methodology for the evaluation of robotic surgery

Robotic surgery has been strongly improved since the beginning of the twenty-first century and chased important level of technical and clinical performances. Within the robotic area, the most worldwide used surgical robot is the da Vinci® system made by Intuitive Surgical Inc. The aim of this study was to evaluate at the hospital scale the robotic surgery (Hospital –Based Health Technology Assessment) in comparison to the open and laparoscopic procedures yet combining a FMECA analysis to accurately assess all those aspects involving patient and staff safety. The total number of robotic procedures directly observed by the surgical department and reported in the following study was 44, including 28 urology interventions and 16 general surgeries. The study confirmed clinical benefits carried out with the robot but bigger complexity in managing the whole surgical system in terms of structural needs, staff and technology. For the future, further steps regard the necessity to dispose of a wider number of robotic procedures in order to strength the analysis reliability and complete the socio-economic assessment with medium and long terms observation. Finally a new FMECA application will be essential to monitor the real effects of the suggested actions on the evaluated risks according to the already known and new failure modes

Universal upper limit on inflation energy scale from cosmic magnetic field

Recently observational lower bounds on the strength of cosmic magnetic fields were reported, based on gamma-ray flux from distant blazars. If inflation is responsible for the generation of such magnetic fields then the inflation energy scale is bounded from above as rho_{inf}^{1/4} < 2.5 times 10^{-7}M_{Pl} times (B_{obs}/10^{-15}G)^{-2} in a wide class of inflationary magnetogenesis models, where B_{obs} is the observed strength of cosmic magnetic fields. The tensor-to-scalar ratio is correspondingly constrained as r< 10^{-19} times (B_{obs}/10^{-15}G)^{-8}. Therefore, if the reported strength B_{obs} \geq 10^{-15}G is confirmed and if any signatures of gravitational waves from inflation are detected in the near future, then our result indicates some tensions between inflationary magnetogenesis and observations.Comment: 12pages, v2: several discussions and references added, version accepted for publication by JCA

Poor sleep quality may independently predict suicidal risk in COVID-19 survivors: a 2-year longitudinal study

Objective: Multiple symptoms of psychiatric, neurological, and physical illnesses may be part of Post-COVID conditions and may pose COVID-19 survivors a high suicidal risk. Accordingly, we aimed to study factors contributing to suicidal risk in Post COVID-19 patients. Method: Consecutive patients with post COVID-19 conditions were followed for 2 years at the University Hospital of Ferrara at baseline (T0), 6 (T1), 12 (T2), and 24 (T3) months. Demographics, and clinical data for all patients included: disease severity, hospital length of stay, comorbidity, clinical complications, sleep quality, cognitive complaints, anxiety and stress-related symptoms, depressive symptoms, and suicidal ideation. Results: The final sample included 81 patients with post COVID survivors. The mean age was 64 + 10,6 years, 35,8% were females, 65,4% had medical comorbidities, and 69,1% had WHO severe form of COVID forms. At T0 more than 90% of patients showed poor sleep quality, 59.3% reported moderate/severe depressive symptoms, and 51.% experienced anxiety, 25.9% experienced post-traumatic stress symptoms. At T0 suicidal ideation, interested 6.1% and at T3 it increased to 7.4%. In the regression analysis, suicidal ideation at baseline was best predicted by poor sleep quality (O.R. 1.71, p=0.044) and, after 2 years, suicidal ideation was best predicted by poor sleep quality experienced at baseline (OR 67.3, p=0.001). Conclusions: Poor sleep quality may play as an independent predictor of suicidal risk in post-COVID survivors. Evaluating and targeting sleep disturbances in COVID survivors is important to prevent the consequences of disrupted sleep in mental health