270 research outputs found

    Radiative feedback and cosmic molecular gas: the role of different radiative sources

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    We present results from multifrequency radiative hydrodynamical chemistry simulations addressing primordial star formation and related stellar feedback from various populations of stars, stellar energy distributions (SEDs) and initial mass functions. Spectra for massive stars, intermediate-mass stars and regular solar-like stars are adopted over a grid of 150 frequency bins and consistently coupled with hydrodynamics, heavy-element pollution and non-equilibrium species calculations. Powerful massive population III stars are found to be able to largely ionize H and, subsequently, He and He+^+, causing an inversion of the equation of state and a boost of the Jeans masses in the early intergalactic medium. Radiative effects on star formation rates are between a factor of a few and 1 dex, depending on the SED. Radiative processes are responsible for gas heating and photoevaporation, although emission from soft SEDs has minor impacts. These findings have implications for cosmic gas preheating, primordial direct-collapse black holes, the build-up of "cosmic fossils" such as low-mass dwarf galaxies, the role of AGNi during reionization, the early formation of extended disks and angular-momentum catastrophe.Comment: 19 pages on MNRA

    Money management and entrepreneurial training in microfinance: impact on beneficiaries and institutions

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    This study uses a randomized control trial to evaluate the outcome of integrating money management and entrepreneurial training into a microcredit program in India. We find positive and significant effects on clients' financial management skills and entrepreneurship abilities, particularly for clients with higher human capital, or more diligent, or having an entrepreneurial idea, and an increase in initiative and self-confidence. Effects appear stronger for clients obliged to attend the training course or more interested in attending it. By considering missed or delayed repayments reduction we assess the benefits of the training provided and of extending it for the institution

    Are bankers “crying wolf”? Type I, type II errors, and deterrence in anti-money laundering: the Italian case

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    Excessive and useless reporting, called the “crying wolf effect,” is a crucial shortcoming that any anti-money laundering (AML) design aims to address. For this reason, in recent years, AML policies in both the US and Europe have switched from a rule-based to a risk-based approach. This study theoretically and empirically investigates whether the risk-based approach delivers the expected results. The theoretical model shows that a trade-off can emerge between accuracy (fewer type-I and type-II errors) and deterrence. The empirical analysis, conducted after the risk-based approach was introduced in Italy, confirms this trade-off. More specifically, deterrence seems a priority, whereas accuracy is sacrificed. In this respect, the data suggest that Italian bankers are likely to “cry wolf.

    Statistical moments of power spectrum: a fast tool for the classification of seismic events recorded on volcanoes

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    Abstract. Spectral analysis has been applied to almost thousand seismic events recorded at Vesuvius volcano (Naples, southern Italy) in 2018 with the aim to test a new tool for a fast event classification. We computed two spectral parameters, central frequency and shape factor, from the spectral moments of order 0, 1, and 2, for each event at seven seismic stations taking the mean among the three components of ground motion. The analyzed events consist of volcano-tectonic earthquakes, low frequency events and unclassified events (landslides, rockfall, thunders, quarry blasts, etc.). Most of them are of low magnitude, and/or low maximum signal amplitude, therefore the signal to noise ratio is very different between the low noise summit stations and the higher noise stations installed at low elevation around the volcano. The results of our analysis show that volcano-tectonic earthquakes and low frequency events are easily distinguishable through the spectral moments values, particularly at seismic stations closer to the epicenter. On the contrary, unclassified events show the spectral parameters values distributed in a broad range which overlap both the volcano-tectonic earthquakes and the low frequency events. Since the computation of spectral parameters is extremely easy and fast for a detected event, it may become an effective tool for event classification in observatory practice

    Dexmedetomidine: current role in burn ICU

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    Dexmedetomidine (DEX) is a relatively recent a2-adrenergic agonist which provides sedation, anxiolysis and analgesia with much less respiratory depression than other sedatives. These characteristics have implemented the use of the drug in the ICUs in order to achieve the target of a “arousable sedation”, thanks to its significant manageability. Its sedative-analgesic properties are also particularly suitable for use in burn ICUs, both adult and pediatric, which is why the current Guidelines have recognized a central role in the management of these categories of patients. Finally, DEX has showed significant anti-inflammatory effect both in animal models and in preliminary clinical trials, reducing vasopressor requirements and main mediators levels of the systemic inflammatory response involved in sepsis and similar processes, suggestingits use for improved outcome in ICU septic patients

    Oral Antiplatelet Therapy for Secondary Prevention of Non-Cardioembolic Ischemic Cerebrovascular Events

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    Stroke is the leading cause of disability and mortality worldwide. After an acute cerebrovascular ischemia, recurrent vascular events, including recurrent stroke or transient ischemic accidents (TIA), occur in around 20% of cases within the first 3 months. In order to minimize this percentage, antiplatelet therapy may play a key role in the management of non-cardioembolic cerebrovascular events. This review will focus on the current evidence of antiplatelet therapies most commonly discussed in practice guidelines and used in clinical practice for the treatment of stroke/TIA complications. The antiplatelet therapies most commonly used and discussed are as follows: aspirin, clopidogrel, and ticagrelor

    The Degeneracy of Galaxy Formation Models

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    We develop a new formalism for modeling the formation and evolution of galaxies within a hierarchical universe. Similarly to standard semi-analytical models we trace galaxies inside dark-matter merger-trees. The formalism includes treatment of feedback, star-formation, cooling, smooth accretion, gas stripping in satellite galaxies, and merger-induced star bursts. However, unlike in other models, each process is assumed to have an efficiency which depends only on the host halo mass and redshift. This allows us to describe the various components of the model in a simple and transparent way. By allowing the efficiencies to have any value for a given halo mass and redshift, we can easily encompass a large range of scenarios. To demonstrate this point, we examine several different galaxy formation models, which are all consistent with the observational data. Each model is characterized by a different unique feature: cold accretion in low mass haloes, zero feedback, stars formed only in merger-induced bursts, and shutdown of star-formation after mergers. Using these models we are able to examine the degeneracy inherent in galaxy formation models, and look for observational data that will help to break this degeneracy. We show that the full distribution of star-formation rates in a given stellar mass bin is promising in constraining the models. We compare our approach in detail to the semi-analytical model of De Lucia & Blaizot. It is shown that our formalism is able to produce a very similar population of galaxies once the same median efficiencies per halo mass and redshift are being used. We provide a public version of the model galaxies on our web-page, along with a tool for running models with user-defined parameters. Our model is able to provide results for a 62.5 h^{-1} Mpc box within just a few seconds.Comment: Accepted for publication in MNRAS. Fig 6 & 7 corrected. For the project page which allows running your own model, see http://www.mpa-garching.mpg.de/galform/sesam

    Temporal evolution of roof collapse from tephra fallout during the 2021-Tajogaite eruption (La Palma, Spain)

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    Although dominantly effusive, the 2021 Tajogaite eruption from Cumbre Vieja volcano (La Palma, Spain) produced a wide tephra blanket over 85 days of activity. About one month after the eruption onset, clean-up operations were implemented to mitigate the impact of tephra load on primary buildings. Here, we present a post-event impact assessment of 764 primary buildings, which expands our empirical knowledge of building vulnerability to tephra fallout to include impacts from long-lasting eruptions. Field observations are analyzed in the perspective of existing fragility curves, high-resolution satellite imagery and a reconstruction of the spatio-temporal evolution of the tephra blanket to characterize the evolution of roof collapse due to static loads over time. Thanks to a chronological correlation between the temporal evolution of tephra sedimentation and the timing of clean-up operations, we quantified their effectiveness in mitigating roof collapse. If no clean-up measures had been taken 11% of the surveyed buildings would have exceeded a 75% probability of roof collapse, while only 10 roof collapses have been observed (1.3% of the analysed buildings). This work provides key insights for further development of emergency plans for the management of long-lasting eruptions characterised by the sustained emission of tephra over weeks to months

    Acute acalculous cholecystitis during the course of primary Epstein-Barr virus infection: a new case and a review of the literature

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    OBJECTIVE: The aim of this study was to describe a case of acute acalculous cholecystitis occurring in the course of primary Epstein-Barr virus (EBV) infection. METHODS: The clinical features of the case were analyzed and compared to those of three other similar cases reported in the international literature. RESULTS: All cases occurred in European females with cholestatic hepatitis, presented with gallbladder wall thickening, and recovered uneventfully without the need for surgical intervention. CONCLUSIONS: Acute acalculous cholecystitis may occur during the course of acute EBV infection, especially in patients with cholestatic hepatitis. Clinicians should be aware of the possible involvement of the gallbladder during EBV infection to avoid unnecessary invasive procedures or the overuse of antibiotics
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