A sampling algorithm to estimate the effect of fluctuations in particle physics data

Background properties in experimental particle physics are typically estimated using large data sets. However, different events can exhibit different features because of the quantum mechanical nature of the underlying physics processes. While signal and background fractions in a given data set can be evaluated using a maximum likelihood estimator, the shapes of the corresponding distributions are traditionally obtained using high-statistics control samples, which normally neglects the effect of fluctuations. On the other hand, if it was possible to subtract background using templates that take fluctuations into account, this would be expected to improve the resolution of the observables of interest, and to reduce systematics depending on the analysis. This study is an initial step in this direction. We propose a novel algorithm inspired by the Gibbs sampler that makes it possible to estimate the shapes of signal and background probability density functions from a given collection of particles, using control sample templates as initial conditions and refining them to take into account the effect of fluctuations. Results on Monte Carlo data are presented, and the prospects for future development are discussed.Comment: 6 pages, 1 figure. Edited to improve readability in line with the published article. This is based on a condensed version for publication in the Proceedings of the International Conference on Mathematical Modelling in the Physical Sciences, IC-MSQUARE 2012, Budapest, Hungary. A more detailed discussion can be found in the preceding version of this arXiv recor

Toward particle-level filtering of individual collision events at the Large Hadron Collider and beyond

Low-energy strong interactions are a major source of background at hadron colliders, and methods of subtracting the associated energy flow are well established in the field. Traditional approaches treat the contamination as diffuse, and estimate background energy levels either by averaging over large data sets or by restricting to given kinematic regions inside individual collision events. On the other hand, more recent techniques take into account the discrete nature of background, most notably by exploiting the presence of substructure inside hard jets, i.e. inside collections of particles originating from scattered hard quarks and gluons. However, none of the existing methods subtract background at the level of individual particles inside events. We illustrate the use of an algorithm that will allow particle-by-particle background discrimination at the Large Hadron Collider, and we envisage this as the basis for a novel event filtering procedure upstream of the official reconstruction chains. Our hope is that this new technique will improve physics analysis when used in combination with state-of-the-art algorithms in high-luminosity hadron collider environments

Toward the estimation of background fluctuations under newly-observed signals in particle physics

When the number of events associated with a signal process is estimated in particle physics, it is common practice to extrapolate background distributions from control regions to a predefined signal window. This allows accurate estimation of the expected, or average, number of background events under the signal. However, in general, the actual number of background events can deviate from the average due to fluctuations in the data. Such a difference can be sizable when compared to the number of signal events in the early stages of data analysis following the observation of a new particle, as well as in the analysis of rare decay channels. We report on the development of a data-driven technique that aims to estimate the actual, as opposed to the expected, number of background events in a predefined signal window. We discuss results on toy Monte Carlo data and provide a preliminary estimate of systematic uncertainty

Unlocking the Power of Late-Evening Snacks: Practical Ready-to-Prescribe Chart Menu for Patients with Cirrhosis

: The efficacy of the late-evening snack (LES) has been extensively studied due to the impact of the longest intermeal duration occurring at night in patients with cirrhosis. While actual clinical guidelines on nutrition in chronic liver disease recommend an LES, no specific nutritional compositions have been reported by the European Association for the Study of the Liver (EASL) and the European Society for Clinical Nutrition and Metabolism (ESPEN). Late-evening snacks vary greatly among studies, including natural foods and/or nutritional supplements, yet oral supplements still need to fully meet the LES's nutritional composition. In addition, many hepatologists need to gain experience in nutritional approaches and have access to registered dieticians who can help them manage patients with liver disease. Therefore, this review study aims to summarise evidence regarding using LESs and the mechanisms behind long starvation in patients with cirrhosis. It also provides a practical nutritional guide with several LES options based on common natural foods tailored to special patients' nutritional requirements and geographical backgrounds. In preventing accelerated starvation and related protein malnutrition and sarcopenia in patients with cirrhosis, the nutritional composition of LESs is essential. The proper and straightforward application of the LES's rational nutrition is an advantage to cirrhotic patients and should be carried out by healthcare professionals to enhance the overall liver function and nutritional status of patients with cirrhosis

A population-based approach to background discrimination in particle physics

Background properties in experimental particle physics are typically estimated using control samples corresponding to large numbers of events. This can provide precise knowledge of average background distributions, but typically does not consider the effect of fluctuations in a data set of interest. A novel approach based on mixture model decomposition is presented as a way to estimate the effect of fluctuations on the shapes of probability distributions in a given data set, with a view to improving on the knowledge of background distributions obtained from control samples. Events are treated as heterogeneous populations comprising particles originating from different processes, and individual particles are mapped to a process of interest on a probabilistic basis. The proposed approach makes it possible to extract from the data information about the effect of fluctuations that would otherwise be lost using traditional methods based on high-statistics control samples. A feasibility study on Monte Carlo is presented, together with a comparison with existing techniques. Finally, the prospects for the development of tools for intensive offline analysis of individual events at the Large Hadron Collider are discussed.Comment: Updated according to the version published in J. Phys.: Conf. Ser. Minor changes have been made to the text with respect to the published article with a view to improving readabilit

Role of Vitamin D in Liver Disease and Complications of Advanced Chronic Liver Disease

Vitamin D is a crucial nutrient with many pleiotropic effects on health and various chronic diseases. The purpose of this review is to provide a detailed report on the pathophysiological mechanisms underlying vitamin D deficiency in patients with chronic liver disease, addressing the different liver etiologies and the condition of advanced chronic liver disease (cirrhosis) with related complications. To date, patients with liver disease, regardless of underlying etiology, have been shown to have reduced levels of vitamin D. There is also evidence of the predictive role of vitamin D values in complications and progression of advanced disease. However, specific indications of vitamin D supplementation are not conclusive concerning what is already recommended in the general population. Future studies should make an effort to unify and validate the role of vitamin D supplementation in chronic liver disease

H&E and OCT4/CD34 for the assessment of lympho-vascular invasion in seminoma and embryonal carcinoma

Background: Lymphovascular invasion (LVI) is a relevant prognostic factor in germ cell tumors of the testis (GCTT), and it is included in the pT stage. However, its detection on hematoxylin and eosin (H&E) slides is very challenging, and previous studies reported fair to moderate inter-observer agreement among dedicated uropathologists. In the present study, we tested H&E and a recently developed in-house double staining for OCT4/CD34 to detect LVI in GCTT. Methods: Nine authors [5 non-uropathologists and 4 uropathologists] independently evaluated 34 consecutive and retrospectively enrolled cases of GCTT. We assessed the inter-observer agreement (Fleiss's Kappa) with both H&E and OCT4/CD34. Besides, we compared the consensus diagnosis on both H&E and OCT4/CD34-stained sections with the original diagnosis to evaluate the pT re-staging (McNemar test) and identify the sources of disagreement. Results: The inter-observer agreement among uropathologists plus non-uropathologists was fair with both H&E (KF=0.398; p < 0.001) and OCT4/CD34 (KF=0.312; p < 0.001). OCT4/CD34 (KF=0.290; p < 0.001) slightly reduces the inter-observer agreement compared to H&E (KF=0.321; p < 0.001) for non-uropathologists; in contrast, OCT4/CD34 (KF=0.293; p < 0.001) significantly reduces the inter-observer agreement compared to H&E (KF=0.529; p < 0.001) for uropathologists, changing it from moderate to fair. Consensus diagnosis with H&E modified the LVI status of the original diagnosis in 8/34 (23.5 %) cases (p: 0.070), with pT re-staging in 2/34 (5.9 %) cases (p: 0.500). Consensus diagnosis with OCT4/CD34 modified the LVI status of the original diagnosis in 8/34 (23.5 %) cases (p: 0.289), with pT re-staging in 3/34 (8.8 %) cases (p: 0.250). The consensus diagnosis with OCT4/CD34 modified the consensus diagnosis with H&E in 8/34 (23.5 %) cases (p: 0.727), and these findings resulted in pT-restaging in 3/34 (8.8 %) cases (p: 0.500). The sources of disagreement among uropathologists were: H&E [artefactual clefts misinterpreted as LVI in 4/6 (66.7 %) cases and true foci of LVI misinterpreted as clusters of histiocytes within the vessels in 2/6 (33.3 %) cases], OCT4/CD34 [artefactual clefts misinterpreted as LVI in 2/8 (25 %) cases, true LVI misinterpreted as artefactual clefts in 2/8 (25 %) cases or floaters in 4/8 (50 %) cases]. Conclusions: OCT4/CD34 does not improve the inter-observer agreement for the assessment of LVI in OCT4(+) GCTT. Consensus diagnosis with H&E modifies the LVI status in a significant number of cases, resulting in changes of the pT stage in a relatively small subgroup. Consensus diagnosis with OCT4/CD34 provides little additional benefit since it cannot exclude mimickers of LVI such as floaters and artefactual clefts. These results argue against the adoption of this diagnostic tool for the routine assessment of OCT4(+) GCTT

Sarcopenia Predicts Major Complications after Resection for Primary Hepatocellular Carcinoma in Compensated Cirrhosis

The burden of post-operative complications of patients undergoing liver resection for hepatocellular carcinoma (HCC) is a cause of morbidity and mortality. Recently, sarcopenia has been reported to influence the outcome of patients with cirrhosis. We aimed to assess factors associated with sarcopenia and its prognostic role in liver surgery candidates. We included all patients with compensated advanced chronic liver disease (cACLD) undergoing liver resection for primary HCC consecutively referred to the University of Bologna from 2014 to 2019 with an available preoperative abdominal CT-scan performed within the previous three months. A total of 159 patients were included. The median age was 68 years, and 80.5% of the patients were male. Sarcopenia was present in 82 patients (51.6%). Age and body mass index (BMI) were associated with the presence of sarcopenia at multivariate analysis. Thirteen (8.2%) patients developed major complications and 14 (8.9%) presented PHLF grade B-C. The model for end-stage liver disease score was associated with the development of major complications, whereas cACLD presence, thrombocytopenia, portal hypertension (PH), Child-Pugh score and Albumin-Bilirubin score were found to be predictors of clinically significative PHLF. The rate of major complications was 11.8% in sarcopenic patients with cACLD compared with no complications (0%) in patients without sarcopenia and cACLD (p = 0.032). The rate of major complications was significantly higher in patients with (16.3%) vs. patients without (0%) sarcopenia (p = 0.012) in patients with PH. In conclusion, sarcopenia, which is associated with age and BMI, may improve the risk stratification of post-hepatectomy major complications in patients with cACLD and PH

Liver Stiffness Measurement Allows Early Diagnosis of Veno-Occlusive Disease/Sinusoidal Obstruction Syndrome in Adult Patients Who Undergo Hematopoietic Stem Cell Transplantation: Results from a Monocentric Prospective Study

ABSTRACT Veno-occlusive disease (VOD), also known as sinusoidal obstruction syndrome (SOS), is a life-threatening complication affecting patients undergoing hematopoietic stem cell transplantation (HSCT). The survival rate is higher when specific therapy is initiated early; thus, improving early, noninvasive diagnosis of VOD/SOS is an important need. In an adult population undergoing HSCT, we aimed to assess the role of liver stiffness measurement (LSM), evaluated by transient elastography (TE), for diagnosing VOD/SOS. Between April 2016 and March 2018, 78 consecutive adult patients with indications for allogeneic HSCT were prospectively included. LSM was performed before HSCT and at days +9/10, +15/17, and +22/24 post-HSCT. New European Society for Blood and Marrow Transplantation criteria were used to establish VOD/SOS diagnosis. Four patients developed VOD/SOS (5.1%) during the study period, with a median time of +17 days post-HSCT. A sudden increase in LSM compared with previously assessed values and pre-HSCT values, was seen in all patients who developed VOD/SOS. LSM increases occurred from 2 to 12 days before clinical SOS/VOD appearance. The VOD/SOS diagnostic performance of increased LSM over pre-HSCT assessment showed an area under the receiver operating characteristic curve of 0.997 (sensitivity 75%; specificity 98.7%). LSM gradually decreased following successful VOD/SOS-specific treatment. Interestingly, LSM values did not increase significantly in patients experiencing hepatobiliary complications (according to the Common Terminology Criteria) other than VOD/SOS. LSM by TE can be considered a promising method to perform an early, preclinical diagnosis and follow-up of VOD/SOS