1,721,673 research outputs found
Il principio di proporzionalità e diniego di detrazione per "consapevolezza" nelle frodi IVA. (The principle of proportionality and the denial of deduction in case of "awareness" in Vat frauds).
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Testing of the foreshock hypothesis within an epidemic like description of seismicity
No full textThe epidemic type aftershock sequence (ETAS) model provides a good description of the post-seismic spatio-temporal clustering of seismicity and is also able to capture some features of the increase of seismic activity caused by foreshocks. Recent results, however, have shown that the number of foreshocks observed in instrumental catalogues is significantly much larger than the one predicted by the ETAS model. Here we show that it is possible to keep an epidemic description of post-seismic activity and, at the same time, to incorporate pre-seismic temporal clustering, related to foreshocks. Taking also into-account the short-term incompleteness of instrumental catalogues, we present a model which achieves very good description of the southern California seismicity both on the aftershock and on the foreshock side. Our results indicate that the existence of a preparatory phase anticipating main shocks represents the most plausible explanation for the occurrence of foreshocks
b-More-Incomplete and b-More-Positive: Insights on a Robust Estimator of Magnitude Distribution
No full textThe b-value in earthquake magnitude-frequency distribution quantifies the relative frequency of large versus small earthquakes. Monitoring its evolution could provide fundamental insights into temporal variations of stress on different fault patches. However, genuine b-value changes are often difficult to distinguish from artificial ones induced by temporal variations of the detection threshold. A highly innovative and effective solution to this issue has recently been proposed by van der Elst (2021, https://doi.org/10.1029/2020jb021027) by means of the b-positive estimator, which is based on analyzing only the positive differences in magnitude between successive earthquakes. Here, we demonstrate the robustness of the estimator, which remains largely unaffected by detection issues due to the properties of conditional probability. We illustrate that this robustness can be further improved by considering positive differences in magnitude, not only between successive earthquakes but also between different pairs of earthquakes. This generalized approach, defined as the "b-more-positive estimator," enhances efficiency by providing a precise estimate of the b-value while including a larger number of earthquakes from an incomplete catalog. However, our analysis reveals that the accuracy of the b estimators diminishes when earthquakes below the completeness threshold are included in the catalog. This leads to the paradoxical observation that greater efficiency is achieved when the catalog is more incomplete. To address this, we introduce the "b-more-incomplete estimator," where the b-more-positive estimator is applied only after artificially filtering the instrumental catalog to make it more incomplete. Our findings show the superior efficiency of the b-more-incomplete method
Estimating the generation interval from the incidence rate, the optimal quarantine duration and the efficiency of fast switching periodic protocols for COVID‐19
Full text linkThe transmissibility of an infectious disease is usually quantified in terms of the reproduction
number Rt representing, at a given time, the average number of secondary cases caused by an
infected individual. Recent studies have enlightened the central role played by w(z), the distribution
of generation times z, namely the time between successive infections in a transmission chain. In
standard approaches this quantity is usually substituted by the distribution of serial intervals, which
is obtained by contact tracing after measuring the time between onset of symptoms in successive
cases. Unfortunately, this substitution can cause important biases in the estimate of Rt . Here we
present a novel method which allows us to simultaneously obtain the optimal functional form of
w(z) together with the daily evolution of Rt , over the course of an epidemic. The method uses, as
unique information, the daily series of incidence rate and thus overcomes biases present in standard
approaches. We apply our method to one year of data from COVID-19 officially reported cases in the
21 Italian regions, since the first confirmed case on February 2020. We find that w(z) has mean value
z ≃ 6 days with a standard deviation a ≃ 1 day, for all Italian regions, and these values are stable
even if one considers only the first 10 days of data recording. This indicates that an estimate of the
most relevant transmission parameters can be already available in the early stage of a pandemic. We
use this information to obtain the optimal quarantine duration and to demonstrate that, in the case
of COVID-19, post-lockdown mitigation policies, such as fast periodic switching and/or alternating
quarantine, can be very efficient
Principio del contraddittorio e codificazione dell’abuso del diritto in materia tributaria
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