Bayesian binary quantile regression for the analysis of Bachelor-Master transition

The multi-cycle organization of modern university systems stimulates the interest in studying the progression to higher level degree courses during the academic career. In particular, after the achievement of the first level qualification (Bachelor degree), students have to decide whether to continue their university studies, by enrolling in a second level (Master) programme, or to conclude their training experience. In this work we propose a binary quantile regression approach to analyze the Bachelor-Master transition phenomenon with the adoption of the Bayesian inferential perspective. In addition to the traditional predictors of academic outcomes, such as the personal characteristics and the field of study, different aspects of the student's performance are considered. Moreover, a new contextual variable, indicating the type of university regulations, is taken into account in the model specification. The utility of the Bayesian binary quantile regression to characterize the non-continuation decision after the first cycle studies is illustrated with an application to administrative data of Bachelor graduates at the School of Economics of Sapienza University of Rome and compared with a more conventional logistic regression approach.Comment: 24 pages, 7 figures and 3 table

Bayesian analysis of ranking data with the constrained Extended Plackett-Luce model

Multistage ranking models, including the popular Plackett-Luce distribution (PL), rely on the assumption that the ranking process is performed sequentially, by assigning the positions from the top to the bottom one (forward order). A recent contribution to the ranking literature relaxed this assumption with the addition of the discrete-valued reference order parameter, yielding the novel Extended Plackett-Luce model (EPL). Inference on the EPL and its generalization into a finite mixture framework was originally addressed from the frequentist perspective. In this work, we propose the Bayesian estimation of the EPL with order constraints on the reference order parameter. The proposed restrictions reflect a meaningful rank assignment process. By combining the restrictions with the data augmentation strategy and the conjugacy of the Gamma prior distribution with the EPL, we facilitate the construction of a tuned joint Metropolis-Hastings algorithm within Gibbs sampling to simulate from the posterior distribution. The Bayesian approach allows to address more efficiently the inference on the additional discrete-valued parameter and the assessment of its estimation uncertainty. The usefulness of the proposal is illustrated with applications to simulated and real datasets.Comment: 20 pages, 4 figures, 4 tables. arXiv admin note: substantial text overlap with arXiv:1803.0288

A simple prognostic index in acute heart failure

Background Rapid effective triage is integral to emergency care in patients hospitalized for heart failure, to guide the type and intensity of therapy. Several indexes and scores have been proposed to predict outcome; most of the them are complex and unfit to use at the bedside. Methods We propose a new prognostic index for in hospital mortality in acute heart failure. The index was built according to the formula; 220 – age – heart rate + systolic blood pressure – ( creatinine X 10). The index was tested in 1628 patients admitted for acute heart failure and enrolled, from November 2007 to December 2009, in the Italian Registry on Heart Failure Outcome ( IN-HF); a prospective, multicentre, observational study. Results The prognostic index was an independent predictor for in hospital mortality risk ( c statistic= 0.74) (p<0.0001), together with left ventricular ejection fraction (p= 0.001), Glycemia ( p= 0.019) and hemoglobin concentration (p = 0.002). Conclusion A simple prognostic index based on variables easily assessed can be useful to predict mortality in acute heart failure at the first arrival in hospital

Indicatori AVA di ateneo: il contesto nazionale e Sapienza a confronto con i grandi atenei

Nell'ambito del sistema di Autovalutazione, Valutazione periodica e Accreditamento (AVA), rivolto alla valutazione periodica dei servizi didattici e all'accreditamento delle sedi e dei corsi di studio, l'ANVUR ha recentemente predisposto una serie di criteri e parametri nalizzati alla valutazione dell'ecienza accademica degli atenei italiani nei suoi molteplici aspetti. In questo articolo vengono analizzati i dati relativi alla prima rilevazione degli indicatori AVA di ateneo sulle cosiddette universita tradizionali (non telematiche). Oltre alla descrizione della variabilita che caratterizza il corpo delle universita italiane, l'analisi ore un inquadramento della performance di Sapienza Universita di Roma nel panorama accademico nazionale

Efficient and accurate inference for mixtures of Mallows models with Spearman distance

The Mallows model occupies a central role in parametric modelling of ranking data to learn preferences of a population of judges. Despite the wide range of metrics for rankings that can be considered in the model specification, the choice is typically limited to the Kendall, Cayley or Hamming distances, due to the closed-form expression of the related model normalizing constant. This work instead focuses on the Mallows model with Spearman distance. An efficient and accurate EM algorithm for estimating finite mixtures of Mallows models with Spearman distance is developed, by relying on a twofold data augmentation strategy aimed at i) enlarging the applicability of Mallows models to samples drawn from heterogeneous populations; ii) dealing with partial rankings affected by diverse forms of censoring. Additionally, a novel approximation of the model normalizing constant is introduced to support the challenging model-based clustering of rankings with a large number of items. The inferential ability of the EM scheme and the effectiveness of the approximation are assessed by extensive simulation studies. Finally, we show that the application to three real-world datasets endorses our proposals also in the comparison with competing mixtures of ranking models.Comment: 20 pages, 6 Figures, 11 Table

I luoghi e l'immagine storica delle Terme di San Calogero nell’isola di Lipari

Nel momento di passaggio al termalismo, alcuni antichi stabilimenti non sono stati in grado di adeguarsi ai nuovi modelli di consumo e di far fronte in tempi rapidi ai cambiamenti imposti anche da una pratica turistica più diffusa e accessibile, giungendo a un progressivo e irreversibile abbandono. Tra questi casi rientrano le Terme di San Calogero a Lipari, che, nonostante le riconosciute proprietà delle sue acque, la diffusa notorietà del luogo sin da epoche remote, versano attualmente in uno stato di incuria e oblio.At the time of transition to thermalism, some ancient establishments were not able to adapt to new consumption patterns and to quickly respond to changes imposed also by a more widespread and accessible tourist practice, reaching a progressive and irreversible abandonment. Among these cases are the Baths of San Calogero in Lipari, which, despite the recognized properties of its waters, the widespread notoriety of the place since ancient times, are currently in a state of neglect and oblivion

Identification of subclinical lung involvement in ACPA-positive subjects through functional assessment and serum biomarkers

Lung involvement is related to the natural history of anti-citrullinated proteins antibodies (ACPA)-positive rheumatoid arthritis (RA), both during the pathogenesis of the disease and as a site of disease-related injury. Increasing evidence suggests that there is a subclinical, early lung involvement during the course of the disease, even before the onset of articular manifestations, which can potentially progress to a symptomatic interstitial lung disease. To date, reliable, noninvasive markers of subclinical lung involvement are still lacking in clinical practice. The aim of this study is to evaluate the diagnostic potential of functional assessment and serum biomarkers in the identification of subclinical lung involvement in ACPA-positive subjects. Fifty ACPA-positive subjects with or without confirmed diagnosis of RA (2010 ARC-EULAR criteria) were consecutively enrolled. Each subject underwent clinical evaluation, pulmonary function testing (PFT) with assessment of diffusion lung capacity for carbon monoxide (DLCO), cardiopulmonary exercise testing (CPET), surfactant protein D (SPD) serum levels dosage and high-resolution computed tomography (HRCT) of the chest. The cohort was composed of 21 ACPA-positive subjects without arthritis (ND), 10 early (disease duration &lt; 6 months, treatment-naïve) RA (ERA) and 17 longstanding (disease duration &lt; 36 months, on treatment) RA (LSRA). LSRA patients had a significantly higher frequency of overall HRCT abnormalities compared to the other groups (p = 0.001). SPD serum levels were significantly higher in ACPA-positive subjects compared with healthy controls (158.5 ± 132.3 ng/mL vs 61.27 ± 34.11 ng/mL; p &lt; 0.0001) and showed an increasing trend from ND subjects to LSRD patients (p = 0.004). Patients with HRCT abnormalities showed significantly lower values of DLCO (74.19 ± 13.2% pred. vs 131.7 ± 93% pred.; p = 0.009), evidence of ventilatory inefficiency at CPET and significantly higher SPD serum levels compared with subjects with no HRCT abnormalities (213.5 ± 157.2 ng/mL vs 117.7 ± 157.3 ng/mL; p = 0.018). Abnormal CPET responses and higher SPD levels were also associated with specific radiological findings. Impaired DLCO and increased SPD serum levels were independently associated with the presence of HRCT abnormalities. Subclinical lung abnormalities occur early in RA-associated autoimmunity. The presence of subclinical HRCT abnormalities is associated with several functional abnormalities and increased SPD serum levels of SPD. Functional evaluation through PFT and CPET, together with SPD assessment, may have a diagnostic potential in ACPA-positive subjects, contributing to the dentification of those patients to be referred to HRCT scan

Percutaneous radiofrequency ablation in intrahepatic cholangiocarcinoma: a retrospective single-center experience

Background & aims: Very few data are available in literature about the role of radiofrequency ablation (RFA) in intrahepatic cholangiocarcinoma (ICC) and previous studies are mainly case reports and case series on a very small number of patients and nodules. In this study, we aimed to evaluate effectiveness and safety of RFA for the treatment of unresectable ICC. Methods: This is a retrospective observational cohort study comprising all consecutive patients treated with RFA for unresectable ICC at Policlinico Sant'Orsola Malpighi Hospital, Bologna, Italy. Primary endpoint was Local Tumor Progression-Free Survival (LTPFS) while Overall Survival (OS) was also assessed as secondary endpoint. Results: From January 2014 to June 2019, 29 patients with 117 nodules underwent RFA. Technique effectiveness 1 month after RFA was 92.3%; median LTPFS was 9.27 months. Univariate analysis and multivariate analysis showed that LTPFS was significantly related to tumor size ≥20 mm. At a median follow up of 39.9 months, median OS from the date of RFA was 27.5 months, with an OS of 89%, 45% and 11% at 1, 2 and 4 years, respectively. Number of overall lesions and the sum of their diameter at the moment of the first RFA significantly affected OS in multivariate analysis. Minor and major complication rates were 14% and 7%, respectively. Conclusion: Tumor size ≥20 mm was associated with lower LTPFS, representing a potential useful threshold value. A careful evaluation of tumor burden appears as a crucial element in choosing the best therapeutic strategy in unresectable ICC