Revisiting Relations between Stochastic Ageing and Dependence for Exchangeable Lifetimes with an Extension for the IFRA/DFRA Property

We first review an approach that had been developed in the past years to introduce concepts of "bivariate ageing" for exchangeable lifetimes and to analyze mutual relations among stochastic dependence, univariate ageing, and bivariate ageing. A specific feature of such an approach dwells on the concept of semi-copula and in the extension, from copulas to semi-copulas, of properties of stochastic dependence. In this perspective, we aim to discuss some intricate aspects of conceptual character and to provide the readers with pertinent remarks from a Bayesian Statistics standpoint. In particular we will discuss the role of extensions of dependence properties. "Archimedean" models have an important role in the present framework. In the second part of the paper, the definitions of Kendall distribution and of Kendall equivalence classes will be extended to semi-copulas and related properties will be analyzed. On such a basis, we will consider the notion of "Pseudo-Archimedean" models and extend to them the analysis of the relations between the ageing notions of IFRA/DFRA-type and the dependence concepts of PKD/NKD

Multivariate negative aging in an exchangeable model of heterogeneity

We introduce an exchangeable model, which accounts for heterogeneity and dependence at a time. Based on this model, we show how situations of multivariate negative ageing arise in a natural way from conditions of heterogeneity

Diagonal sections of copulas, multivariate conditional hazard rates and distributions of order statistics for minimally stable lifetimes

As a motivating problem, we aim to study some special aspects of the marginal distributions of the order statistics for exchangeable and (more generally) for minimally stable non-negative random variables $T_{1},...,T_{r}$. In any case, we assume that $T_{1},...,T_{r}$ are identically distributed, with a common survival function $\overline{G}$ and their survival copula is denoted by $K$. The diagonal's and subdiagonals' sections of $K$, along with $\overline{G}$, are possible tools to describe the information needed to recover the laws of order statistics. When attention is restricted to the absolutely continuous case, such a joint distribution can be described in terms of the associated multivariate conditional hazard rate (m.c.h.r.) functions. We then study the distributions of the order statistics of $T_{1},...,T_{r}$ also in terms of the system of the m.c.h.r. functions. We compare and, in a sense, we combine the two different approaches in order to obtain different detailed formulas and to analyze some probabilistic aspects for the distributions of interest. This study also leads us to compare the two cases of exchangeable and minimally stable variables both in terms of copulas and of m.c.h.r. functions. The paper concludes with the analysis of two remarkable special cases of stochastic dependence, namely Archimedean copulas and load sharing models. This analysis will allow us to provide some illustrative examples, and some discussion about peculiar aspects of our results

Sopravvivenza e mortalità per causa

Analisi della mortalità generale e per causa nelle regioni italian

Smoking habits among Italian adolescents: what has changed in the last decade?

Tobacco use, alcohol abuse, overweight and obesity are risk factors for numerous diseases in Italy as elsewhere. However, children and adolescents are not usually included in official national surveys although it is at this stage of life when unhealthy habits are often established. Italian participation in HBSC and GYTS surveys allows our country to implement standardized surveillance systems providing reliable information on tobacco-related behaviors of this population. Data from three HBSC surveys (2002–2010) show that following the drop in the first half of the decade, prevalence of tobacco use stabilized in the second half. The decline was significant for younger age groups, while prevalence of regular tobacco use remained stable among 15-year-olds. Many adolescents reported being exposed to secondhand smoke, to have at least one parent who smokes, and having seen teachers and students smoking at school. Although the sale of tobacco products to minors is prohibited, the vast majority had no trouble in buying cigarettes. Data from GYTS and HBSC surveys provide a wealth of information about attitudes and behaviors of Italian adolescents with respect to smoking. Despite some progress, sizeable gaps remain in meeting standard recommendations for discouraging smoking initiation and motivating adolescent smokers to quit the habit

Outpatient therapeutic chronic opioid consumption in Italy: a one-year survey.

BACKGROUND: In Italy since the 38/2010 law concerning Palliative Care and pain therapy has been promulgated, the consumption of opioids started increasing. However, despite the availability of a large amount of data regarding opioid prescription, a database including all patients on chronic opioid therapy does not yet exist. METHODS: Retrospective analysis of analgesic opioid consumption was performed between January 2013 and December 2013 using the data of national refunded medications for outpatients, collected by Italian Ministry of Health. We considered patients on chronic opioid therapy those patients with at least three opioids prescriptions in three consecutive months and/or six opioid prescriptions in six even not consecutive months in the observation period. We considered cancer patients those with neoplasm exemption code in the scheduled prescription and/or patients with at least one ROOs prescription (rapid onset opioids, approved in Italy for Break Through cancer Pain-BTcP- only). We also calculated the patient's morphine daily mean dose (MED) converting all prescribed opioids in equivalent of morphine using specific conversion tables. RESULTS: This census revealed a total of 422,542 patients in chronic therapy with opioids, of those 369.961 with chronic non-cancer pain and 52,581 with chronic cancer pain. This represents about 4% of the estimated requirement in Italy for both groups based on previous surveys regarding the prevalence of chronic pain. CONCLUSIONS: Relatively to MED, We found that in Italy chronic cancer pain patients receive doses similar to patients with cancer pain in other Literature reports, whereas patients with chronic non-cancer pain received lower dosages

IBIS/PICsIT in-flight performances

PICsIT (Pixellated Imaging CaeSium Iodide Telescope) is the high energy detector of the IBIS telescope on-board the INTEGRAL satellite. PICsIT operates in the gamma-ray energy range between 175 keV and 10 MeV, with a typical energy resolution of 10% at 1 MeV, and an angular resolution of 12 arcmin within a \~100 square degree field of view, with the possibility to locate intense point sources in the MeV region at the few arcmin level. PICsIT is based upon a modular array of 4096 independent CsI(Tl) pixels, ~0.70 cm^2 in cross-section and 3 cm thick. In this work, the PICsIT on-board data handling and science operative modes are described. This work presents the in-flight performances in terms of background count spectra, sensitivity limit, and imaging capabilities.Comment: 8 pages, 4 figures. Accepted for publication on A&A, special issue on First Science with INTEGRA