260 research outputs found

    XMM-Newton observations of the low-luminosity cataclysmic variable V405 Pegasi

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    V405 Peg is a low-luminosity cataclysmic variable (CV) that was identified as the optical counterpart of the bright, high-latitude ROSAT all-sky survey source RBS1955. The system was suspected to belong to a largely undiscovered population of hibernating CVs. Despite intensive optical follow-up its subclass however remained undetermined. We want to further classify V405 Peg and understand its role in the CV zoo via its long-term behaviour, spectral properties, energy distribution and accretion luminosity. We perform a spectral and timing analysis of \textit{XMM-Newton} X-ray and ultra-violet data. Archival WISE, HST, and Swift observations are used to determine the spectral energy distribution and characterize the long-term variability. The X-ray spectrum is characterized by emission from a multi-temperature plasma. No evidence for a luminous soft X-ray component was found. Orbital phase-dependent X-ray photometric variability by ∼50%\sim50\% occurred without significant spectral changes. No further periodicity was significant in our X-ray data. The average X-ray luminosity during the XMM-Newton observations was L_X, bol simeq 5e30 erg/s but, based on the Swift observations, the corresponding luminosity varied between 5e29 erg/s and 2e31 erg/son timescales of years. The CV subclass of this object remains elusive. The spectral and timing properties show commonalities with both classes of magnetic and non-magnetic CVs. The accretion luminosity is far below than that expected for a standard accreting CV at the given orbital period. Objects like V405 Peg might represent the tip of an iceberg and thus may be important contributors to the Galactic Ridge X-ray Emission. If so they will be uncovered by future X-ray surveys, e.g. with eROSITA.Comment: A&A, in pres

    CTprintNet: An Accurate and Stable Deep Unfolding Approach for Few-View CT Reconstruction

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    In this paper, we propose a new deep learning approach based on unfolded neural networks for the reconstruction of X-ray computed tomography images from few views. We start from a model-based approach in a compressed sensing framework, described by the minimization of a least squares function plus an edge-preserving prior on the solution. In particular, the proposed network automatically estimates the internal parameters of a proximal interior point method for the solution of the optimization problem. The numerical tests performed on both a synthetic and a real dataset show the effectiveness of the framework in terms of accuracy and robustness with respect to noise on the input sinogram when compared to other different data-driven approaches

    Il benessere a scuola: sviluppo e risultati di un’inchiesta partecipativa

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    Il contributo presenta i risultati di un’inchiesta tramite questionario sulle condizioni di benessere e disagio a scuola, che ha coinvolto 1389 studentesse e studenti di un Liceo di una città metropolitana dell’Italia settentrionale. Lo strumento d’indagine utilizzato è il prodotto di un processo partecipativo al quale hanno preso parte diverse componenti della comunità scolastica insieme ai ricercatori esterni. Il processo di costruzione ha preso le mosse da un precedente strumento elaborato da un gruppo di studentesse e studenti e ha tenuto conto sia di modelli disponibili nella letteratura di ricerca, sia dei risultati di una indagine esplorativa condotta mediante focus group. Le analisi fattoriali e di scala presentate in questo studio mostrano una struttura multidimensionale del costrutto di benessere che si adatta ai dati raccolti e risulta complessivamente coerente con alcuni studi recenti che ricadono nello stesso ambito. In particolare, il modello proposto considera dieci dimensioni del benessere a scuola, definite come adeguatezza e sicurezza degli spazi fisici, senso di protezione da comportamenti avversi emessi da insegnanti, o da altri studenti, informazione, espressione e partecipazione, rapporto con gli insegnanti, didattica, funzione formativa della valutazione, rapporto con i compagni, soddisfazione per la scelta dell'indirizzo e dell'Istituto. Infine, si presentano alcuni risultati dell’analisi delle differenze significative tra i gruppi secondo l’anno di scolarità, l’occorrenza di debiti formativi e l’identità di genere.This article presents the results of a questionnaire survey on the conditions of well-being and discomfort at school, in which 1389 students from a high school in a large northern Italian city took part. The survey instrument used is the result of a participatory process involving different components of the school community together with external researchers. The construction process started from a previous instrument developed by a group of students and took into account both models available in the research literature and the results of an exploratory study conducted through focus groups. The factor and scale analyses presented in this study show a multidimensional structure of the construct of well-being that fits the data collected and is broadly consistent with a number of recent studies in the same field. In particular, the proposed model considers ten dimensions of wellbeing in school, defined as the adequacy and safety of physical spaces, the feeling of protection from detrimental behaviour by teachers or other students, information, voice and participation, relationship with teachers, teaching methods, formative function of assessment, relationship with peers, and satisfaction with the choice of course and institution. Finally, some results of the analysis of significant differences between the groups according to school year, the occurrence of subject resits, and gender identity are presented

    Are we ready for scaling up restoration actions? An insight from Mediterranean macroalgal canopies

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    Extensive loss of macroalgal forests advocates for large-scale restoration interventions, to compensate habitat degradation and recover the associated ecological functions and services. Yet, restoration attempts have generally been limited to small spatial extensions, with the principal aim of developing efficient restoration techniques. Here, the success of outplanting Cystoseira amentacea v. stricta germlings cultured in aquaria was experimentally explored at a scale of tens of kms, by means of a multifactorial experimental design. In the intertidal rocky shores of SE Italy, locations with a continuous distribution for hundreds of meters or with few thalli forming patches of few centimeters of C. amentacea canopy were selected. In each location, the effects of adult conspecifics and the exclusion of macrograzers (salema fish and sea urchins) on the survival of germlings were tested. We evaluated the most critical determinants of mortality for germlings, including the overlooked pressure of mesograzers (e.g. amphipods, small mollusks, polychaetes). Despite the high mortality observed during outplanting and early settlement stages, survival of C. amentacea germlings was consistently favored by the exclusion of macrograzers, while the presence of adult conspecifics had no effects. In addition, the cost analysis of the interventions showed the feasibility of the ex-situ method, representing an essential tool for preserving Cystoseira forests. Large scale restoration is possible but requires baseline information with an in-depth knowledge of the species ecology and of the areas to be restored, together with the development of specific cultivation protocols to make consistently efficient restoration interventions

    Obesity as a social phenomenon: A narrative review

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    BACKGROUND: obesity is one of the most prevalent diseases all over the world. Because of its high social impact, the broadest possible approach on several levels - and not limited only to clinical aspect - is needed to better understand and face the challenges obesity poses to public health. OBJECTIVES: to analyse, through the main evidence, the so- cial impact of weight excess in the general population and the actions aimed at mitigating its negative effects. DESIGN: narrative review. SETTING: data obtained from the sources included in the study were gathered and analyzed in five macroareas: Health Inequality, Society, Work, Impact on Social Medicine (focused on the Italian model), and Social Costs. RESULTS: each category showed a bilateral relationship with obesity having a significant impact for the community. CONCLUSIONS: for each field, various actions should be taken at institutional level. Many recommendations and actions have already been taken worldwide, but they alone seem to be not enough. This work points out that, in order to combat obesity and bring about a slowdown of this pandemic, the en- tire scientific community and institutions must work together to identify and design programmes that are truly effective

    Crystal structure of 1-benzyl-3-methyl-1 H

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    Role of computed tomography in predicting critical disease in patients with covid-19 pneumonia: a retrospective study using a semiautomatic quantitative method

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    Background: So far, only a few studies evaluated the correlation between CT features and clinical outcome in patients with COVID-19 pneumonia. Purpose: To evaluate CT ability in differentiating critically ill patients requiring invasive ventilation from patients with less severe disease. Methods: We retrospectively collected data from patients admitted to our institution for COVID-19 pneumonia between March 5th-24th. Patients were considered critically ill or non-critically ill, depending on the need for mechanical ventilation. CT images from both groups were analyzed for the assessment of qualitative features and disease extension, using a quantitative semiautomatic method. We evaluated the differences between the two groups for clinical, laboratory and CT data. Analyses were conducted on a per-protocol basis. Results: 189 patients were analyzed. PaO2/FIO2 ratio and oxygen saturation (SaO2) were decreased in critically ill patients. At CT, mixed pattern (ground glass opacities (GGO) and consolidation) and GGO alone were more frequent respectively in critically ill and in non-critically ill patients (p < 0.05). Lung volume involvement was significantly higher in critically ill patients (38.5 % vs. 5.8 %, p < 0.05). A cut-off of 23.0 % of lung involvement showed 96 % sensitivity and 96 % specificity in distinguishing critically ill patients from patients with less severe disease. The fraction of involved lung was related to lactate dehydrogenase (LDH) levels, PaO2/FIO2 ratio and SaO2 (p < 0.05). Conclusion: Lung disease extension, assessed using quantitative CT, has a significant relationship with clinical severity and may predict the need for invasive ventilation in patients with COVID-19
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