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

On the frequency distribution of neutral particles from low-energy strong interactions

Copyright © 2017 Federico Colecchia and Akram Khan. The rejection of the contamination, or background, from low-energy strong interactions at hadron collider experiments is a topic that has received significant attention in the field of particle physics. This article builds on a particle-level view of collision events, in line with recently-proposed subtraction methods. While conventional techniques in the field usually concentrate on probability distributions, our study is, to our knowledge, the first attempt at estimating the frequency distribution of background particles across the kinematic space inside individual collision events. In fact, while the probability distribution can generally be estimated given a model of low-energy strong interactions, the corresponding frequency distribution inside a single event typically deviates from the average and cannot be predicted a priori. We present preliminary results in this direction, and establish a connection between our technique and the particle weighting methods that have been the subject of recent investigation at the Large Hadron Collider

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

Fish oil-based emulsion for the treatment of parenteral nutrition associated liver disease in an adult patient

Background & aims: Reversal of parenteral nutrition associated liver disease with fish oil emulsion (FO) has been reported in infants. We report a similar case in an adult patient. Methods: A 58 year-old female on home parenteral nutrition for a short bowel syndrome due to Crohn's disease, showed a progressive worsening of liver steatosis, and a persistent increase of the plasma liver function tests (LFTs). LFTs, serum alpha-tochopherol, red blood cell membrane fatty acids and liver histology were evaluated before and after an 8 month treatment with FO. Results: The patient's LFT's improved. There was an increase of the n-3 and a decrease of the n-6 series of fatty acids in erythrocyte membrane. There was an approximate 30% increase in vitamin E status. Before FO, liver histology showed a non-alcoholic steatohepatitis with grade 2 steatosis and inflammation and stage 3 fibrosis. After the treatment, steatosis and inflammation were grade 1, whereas fibrosis remained at stage 3. Conclusions: Infusion of FO was associated with consistent changes of cell membrane fatty acid structure and with mild improvement of vitamin E status. A potential role of FO in decreasing liver steatosis and inflammation with no change of liver fibrosis might be suggested. © 2010 European Society for Clinical Nutrition and Metabolism

Predictive factors for hepatocellular carcinoma recurrence after curative treatments

Hepatocellular carcinoma (HCC) is the fifth most common neoplasm worldwide. Recurrence of HCC after resection or loco-regional therapies represents an important clinical issue as it affects up to 70% of patients. This can be divided into early or late, if it occurs within or after 24 months after treatment, respectively. While the predictive factors for early recurrence are mainly related to tumour biology (local invasion and intrahepatic metastases), late recurrences are mainly related to de novo tumour formation. Thus, it is important to recognize these factors prior to any treatment in each patient, in order to optimize the treatment strategy and follow-up after treatment. The aim of this review is to summarize the current evidence available regarding predictive factors for the recurrence of HCC, according to the different therapeutic strategies available. In particular, we will discuss the role of new ultrasound-based techniques and biological features, such as tumor-related and circulating biomarkers, in predicting HCC recurrence. Recent advances in imaging-related parameters in computed-tomography scans and magnetic resonance imaging will also be discussed

Clinical presentation of celiac disease and diagnosis accuracy in a single-center european pediatric cohort over 10 years

(1) Background: Changes in the clinical presentation of celiac disease (CD) in children have been reported. The guidelines of the European Society of Pediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) allow esophagogastroduodenoscopy (EGD) with biopsies to be avoided under specific circumstances. We aimed to assess the clinical picture of pediatric CD patients at diagnosis and to validate ESPGHAN non-biopsy criteria. (2) Methods: Patients with suspected CD or undergoing screening from 2004 to 2014 at the University Hospital in Modena, Italy were enrolled. The accuracy of ESPGHAN non-biopsy criteria and modified versions were assessed. (3) Results: In total, 410 patients were enrolled, of whom 403 were considered for analysis. Of the patients considered, 45 were asymptomatic and diagnosed with CD (11.2%) while 358 patients (88.2%) were symptomatic, of whom 295 were diagnosed with CD. Among symptomatic CD patients, 57 (19.3%) had gastrointestinal symptoms, 98 (33%) had atypical symptoms and 140 (47.4%) had both. No difference was found for the presence of gastrointestinal symptoms at different ages. The non-biopsy ESPGHAN criteria yielded an accuracy of 59.4% with a positive predictive value (PPV) of 100%; 173 out of 308 EGD (56.2%) could have been avoided. The modified 7× and 5× upper limit of normal cut-offs for IgA anti tissue-transglutaminase reached 60.7% and 64.3% of EGD avoided, respectively. (4) Conclusions: Over 10 years, late age at diagnosis and increased rates of atypical CD presentation were found. ESPGHAN non-biopsy criteria are accurate for CD diagnosis and allow half of unneeded EGD to be avoided. Modified versions allowed sparing a greater number of EGD

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

Are the Expanded Baveno VI Criteria really safe to screen compensated cirrhotic patients for high-risk varices?

The Expanded Baveno VI criteria [1] have been recently proposed as a new screening strategy for high-risk varices (HRV), able to increase the rate of spared upper endoscopies (EGDs) and improve upon the original Baveno VI Criteria [2]. To date, few studies have investigated the performance and safety of these criteria [3,4]. The recent work by Bae et al. [4] is the first one to report a high rate (>5%) of missed HRV by the expanded criteria, questioning their efficiency in safely ruling out HRV (sensitivity 81%, NPV 93%, LR- 0.30

Antibiotic prophylaxis in patients with cirrhosis: Current evidence for clinical practice

Patients with cirrhosis show an increased susceptibility to infection due to disease-related immune-dysfunction. Bacterial infection therefore represents a common, often detrimental event in patients with advanced liver disease, since it can worsen portal hypertension and impair the function of hepatic and extrahepatic organs. Among pharmacological strategies to prevent infection, antibiotic prophylaxis remains the first-choice, especially in high-risk groups, such as patients with acute variceal bleeding, low ascitic fluid proteins, and prior episodes of spontaneous bacterial peritonitis. Nevertheless, antibiotic prophylaxis has to deal with the changing bacterial epidemiology in cirrhosis, with increased rates of gram-positive bacteria and multidrug resistant rods, warnings about quinolones-related side effects, and low prescription adherence. Short-term antibiotic prophylaxis is applied in many other settings during hospitalization, such as before interventional or surgical procedures, but often without knowledge of local bacterial epidemiology and without strict adherence to antimicrobial stewardship. This paper offers a detailed overview on the application of antibiotic prophylaxis in cirrhosis, according to the current evidence

Creatine Supplementation to Improve Sarcopenia in Chronic Liver Disease: Facts and Perspectives

Creatine supplementation has been one of the most studied and useful ergogenic nutritional support for athletes to improve performance, strength, and muscular mass. Over time creatine has shown beneficial effects in several human disease conditions. This review aims to summarise the current evidence for creatine supplementation in advanced chronic liver disease and its complications, primarily in sarcopenic cirrhotic patients, because this condition is known to be associated with poor prognosis and outcomes. Although creatine supplementation in chronic liver disease seems to be barely investigated and not studied in human patients, its potential efficacy on chronic liver disease is indirectly highlighted in animal models of non-alcoholic fatty liver disease, bringing beneficial effects in the fatty liver. Similarly, encephalopathy and fatigue seem to have beneficial effects. Creatine supplementation has demonstrated effects in sarcopenia in the elderly with and without resistance training suggesting a potential role in improving this condition in patients with advanced chronic liver disease. Creatine supplementation could address several critical points of chronic liver disease and its complications. Further studies are needed to support the clinical burden of this hypothesis