Multivariate L\'evy Models: Calibration and Pricing

The goal of this paper is to investigate how the marginal and dependence structures of a variety of multivariate L\'evy models affect calibration and pricing. To this aim, we study the approaches of Luciano and Semeraro (2010) and Ballotta and Bonfiglioli (2016) to construct multivariate processes. We explore several calibration methods that can be used to fine-tune the models, and that deal with the observed trade-off between marginal and correlation fit. We carry out a thorough empirical analysis to evaluate the ability of the models to fit market data, price exotic derivatives, and embed a rich dependence structure. By merging theoretical aspects with the results of the empirical test, we provide tools to make suitable decisions about the models and calibration techniques to employ in a real context

Inventory management of vertically differentiated perishable products with stock-out based substitution

The need for optimal inventory control strategies for perishable items is of the utmost importance to reduce the large share of food products that expire before consumption and to achieve responsible food stocking policies. Our study allows for a multi-item setting with substitution between similar goods, deterministic deterioration, delivery lead times and seasonality. Namely, we model demand by a linear discrete choice model to represent a vertical differentiation between products. The verticality assumption is further applied in a novel way within product categories. Specifically, the same product typology is vertically decomposed according to the age of the single stock-keeping unit in a quality-based manner. We compare two different policies to select the daily size of the orders for each product. On the one hand, we apply one of the most classical approaches in inventory management, relying on the Order-Up-To policy, modified to deal with the seasonality. On the other hand, we operate a state-of-the-art actor-critic technique: Soft Actor-Critic (SAC). Although similar in terms of performance, the two policies show diverse replenishment patterns, handling products differently

Data-driven control of a Pendulum Wave Energy Converter: A Gaussian Process Regression approach

The energy coming from the motion of the waves of seas and oceans could be an important component in the solution of the energy problem related to the pursuit of alternatives to fossil fuels. However, wave energy is still technologically immature and it has not reached the economic feasibility required for economy of scale. One of the major technological challenges for the achievement of this goal is the development of control strategies capable of maximizing the extracted energy, adapting to the conditions of the seas and oceans that surround the Wave Energy Converter (WEC) devices. To perform this task, control systems often adopt explicitly control-oriented models, that are by nature affected by uncertainties. On the contrary, to address the problem a data-driven solution is proposed here. The presented strategy applies an optimization approach based on a Gaussian Process Regression (GPR) metamodel to learn the control strategy to be applied. In order to accelerate the learning process, we present a novel method that exploits in the initial phase a previous knowledge given by simulations with the system model and based on the co-kriging concept. To test this approach the Pendulum Wave Energy Converter has been adopted as a case study. To differentiate the previous knowledge and the real system behaviour, a simplified linear model is used to obtain the prior knowledge, while a complex nonlinear one acts as the environment in which simulate the behaviour of the real system. A month-long simulation is used to validate the effectiveness of the proposed strategy, showing the ability of adapting to a real system different from the simplified model on the basis only of data, and overcoming the model-based strategy in terms of performance

Faecalibacterium prausnitzii is not decreased in symptomatic uncomplicated diverticular disease of the colon

In this letter, assessment of the amount of fecal Faecalibacterium prausnitzii in symptomatic uncomplicated diverticular disease (SUDD) is described. Among 44 consecutive patients, comprising 15 SUDD patients, 13 patients with asymptomatic diverticulosis (AD), and 16 healthy controls (HC), the fecal amount of Faecalibacterium prausnitzii was not found to be significantly different between HC, AD and SUDD subjects (p=0.871). Moreover, its count in the HC microbiota (-4.57 +/- 2.15) was lower compared with those in the AD (-4.11 +/- 1.03) and SUDD subjects (-4.03 +/- 1.299). This behavior seems to be different from that occurring in inflammatory bowel disease (IBD) and similar to that of other mucin-degrading species in a SUDD setting

A case of arrhythmogenic right ventricular cardiomyopathy with biventricular involvement

We reported a case of a young adult male aged 18 years admitted in our institution for syncope during a basketball match. No previous symptoms were reported. Electrocardiogram (ECG) showed T-wave inversion in the anterior leads and an incomplete right bundle branch block. Surprisingly, a complete echocardiographic evaluation demonstrated the presence of severe right ventricular enlargement with significant wall motion abnormalities, apical aneurysm and reduced systolic function. Cardiac Magnetic Resonance was pathognomonic for a fibro-fatty replacement of both ventricles. We decided for a subcutaneous defibrillator implantation and, after inducing a ventricular fibrillation to test the device status, epsilon wave appeared on the ECG. This clinical scenario depicted an advanced arrhythmogenic right ventricular cardiomyopathy at its first clinical manifestation

Discriminating radiation injury from recurrent tumor with [18F]PARPi and amino acid PET in mouse models

Background Radiation injury can be indistinguishable from recurrent tumor on standard imaging. Current protocols for this differential diagnosis require one or more follow-up imaging studies, long dynamic acquisitions, or complex image post-processing; despite much research, the inability to confidently distinguish between these two entities continues to pose a significant dilemma for the treating clinician. Using mouse models of both glioblastoma and radiation necrosis, we tested the potential of poly(ADP-ribose) polymerase (PARP)-targeted PET imaging with [18F]PARPi to better discriminate radiation injury from tumor. Results In mice with experimental radiation necrosis, lesion uptake on [18F]PARPi-PET was similar to contralateral uptake (1.02 ± 0.26 lesion/contralateral %IA/ccmax ratio), while [18F]FET-PET clearly delineated the contrast-enhancing region on MR (2.12 ± 0.16 lesion/contralateral %IA/ccmax ratio). In mice with focal intracranial U251 xenografts, tumor visualization on PARPi-PET was superior to FET-PET, and lesion-to-contralateral activity ratios (max/max, p = 0.034) were higher on PARPi-PET than on FET-PET. Conclusions A murine model of radiation necrosis does not demonstrate [18F]PARPi avidity, and [18F]PARPi-PET is better than [18F]FET-PET in distinguishing radiation injury from brain tumor. [18F]PARPi-PET can be used for discrimination between recurrent tumor and radiation injury within a single, static imaging session, which may be of value to resolve a common dilemma in neuro-oncology

The DICA Endoscopic Classification for Diverticular Disease of the Colon Shows a Significant Interobserver Agreement among Community Endoscopists: an International Study

Background & Aims: The Diverticular Inflammation and Complication Assessment (DICA) endoscopic classification of diverticulosis and diverticular disease (DD) is currently available. It scores severity of the disease as DICA 1, DICA 2 and DICA 3. Our aim was to assess the agreement on this classification in an international endoscopists community setting. Methods: A total of 96 doctors (82.9% endoscopists) independently scored a set of DD endoscopic videos. The percentages of overall agreement on DICA score and a free-marginal multirater kappa (kappa) coefficient were reported as statistical measures of interrater agreement. Results: Overall agreement in using DICA was 91.8% with a free-marginal kappa of 88% (95% CI 80-95). The overall agreement levels were: DICA 1, 85.2%; DICA 2, 96.5%; DICA 3, 99.5%. The free marginal. was: DICA 1 = 0.753, DICA 2 = 0.958, DICA 3 = 0.919. The agreement about the main endoscopic items was 83.4% (k 67%) for diverticular extension, 62.6% (k 65%) for number of diverticula for each district, 86.8% (k 82%) for presence of inflammation, and 98.5 (k 98%) for presence of complications. Conclusions: The overall interrater agreement in this study ranges from good to very good. DICA score is a simple and reproducible endoscopic scoring system for diverticulosis and DD

International Consensus on Diverticulosis and Diverticular Disease. Statements from the 3rd International Symposium on Diverticular Disease

The statements produced by the Chairmen and Speakers of the 3rd International Symposium on Diverticular Disease, held in Madrid on April 11th-13th 2019, are reported. Topics such as current and evolving concepts on the pathogenesis, the course of the disease, the news in diagnosing, hot topics in medical and surgical treatments, and finally, critical issues on the disease were reviewed by the Chairmen who proposed 39 statements graded according to level of evidence and strength of recommendation. Each topic was explored focusing on the more relevant clinical questions. The vote was conducted on a 6-point scale and consensus was defined a priori as 67% agreement of the participants. The voting group consisted of 124 physicians from 18 countries, and agreement with all statements was provided. Comments were added explaining some controversial areas

Treatment of Relapsing Mild-to-Moderate Ulcerative Colitis With the Probiotic VSL#3 as Adjunctive to a Standard Pharmaceutical Treatment: A Double-Blind, Randomized, Placebo-Controlled Study

OBJECTIVES: VSL#3 is a high-potency probiotic mixture that has been used successfully in the treatment of pouchitis. The primary end point of the study was to assess the effects of supplementation with VSL#3 in patients affected by relapsing ulcerative colitis (UC) who are already under treatment with 5-aminosalicylic acid (ASA) and/or immunosuppressants at stable doses. METHODS: A total of 144 consecutive patients were randomly treated for 8 weeks with VSL#3 at a dose of 3,600 billion CFU/day (71 patients) or with placebo (73 patients). RESULTS: In all, 65 patients in the VSL#3 group and 66 patients in the placebo group completed the study. The decrease in ulcerative colitis disease activity index (UCDAI) scores of 50% or more was higher in the VSL#3 group than in the placebo group (63.1 vs. 40.8; per protocol (PP) P=0.010, confidence interval (CI)\u2089\u2085(%) 0.51-0.74; intention to treat (ITT) P=0.031, CI\u2089\u2085(%) 0.47-0.69). Significant results with VSL#3 were recorded in an improvement of three points or more in the UCDAI score (60.5% vs. 41.4%; PP P=0.017, CI\u2089\u2085(%) 0.51-0.74; ITT P=0.046, CI\u2089\u2085(%) 0.47-0.69) and in rectal bleeding (PP P=0.014, CI\u2089\u2085(%) 0.46-0.70; ITT P=0.036, CI\u2089\u2085(%) 0.41-0.65), whereas stool frequency (PP P=0.202, CI\u2089\u2085(%) 0.39-0.63; ITT P=0.229, CI\u2089\u2085(%) 0.35-0.57), physician's rate of disease activity (PP P=0.088, CI\u2089\u2085(%) 0.34-0.58; ITT P=0.168, CI\u2089\u2085(%) 0.31-0.53), and endoscopic scores (PP P=0.086, CI\u2089\u2085(%) 0.74-0.92; ITT P=0.366, CI\u2089\u2085(%) 0.66-0.86) did not show statistical differences. Remission was higher in the VSL#3 group than in the placebo group (47.7% vs. 32.4%; PP P=0.069, CI\u2089\u2085(%) 0.36-0.60; ITT P=0.132, CI\u2089\u2085(%) 0.33-0.56). Eight patients on VSL#3 (11.2%) and nine patients on placebo (12.3%) reported mild side effects. CONCLUSIONS: VSL#3 supplementation is safe and able to reduce UCDAI scores in patients affected by relapsing mild-to-moderate UC who are under treatment with 5-ASA and/or immunosuppressants. Moreover, VSL#3 improves rectal bleeding and seems to reinduce remission in relapsing UC patients after 8 weeks of treatment, although these parameters do not reach statistical significance