In experiments searching for neutrinoless double-beta decay, the possibility of identifying the two emitted electrons is a powerful tool in rejecting background events and therefore improving the overall sensitivity of the experiment. In this paper we present the first measurement of the efficiency of a cut based on the different event signatures of double and single electron tracks, using the data of the NEXT-White detector, the first detector of the NEXT experiment operating underground. Using a 228 Th calibration source to produce signal-like and background-like events with energies near 1.6 MeV, a signal efficiency of 71.6 ± 1.5 stat ± 0.3 sys % for a background acceptance of 20.6 ± 0.4 stat ± 0.3 sys % is found, in good agreement with Monte Carlo simulations. An extrapolation to the energy region of the neutrinoless double beta decay by means of Monte Carlo simulations is also carried out, and the results obtained show an improvement in background rejection over those obtained at lower energies.

Intestinal ganglioneuromatosis is a rare disorder of the enteric nervous system. It is often associated with neurofibromatosis type 1 and multiple endocrine neoplasia type 2b but, more rarely, it can present in a sporadic and isolated form. A 66-year-old man presented with a 14-year history of iron deficiency anaemia, with no visible bleeding, requiring occasional blood transfusions. Haematological causes of anaemia were thoroughly excluded, and conventional endoscopic and radiological examinations showed no lesions. Capsule enteroscopy identified an ulcerated stenosis in the small bowel, but the biopsies taken at balloon enteroscopy were inconclusive. The patient underwent a laparotomy, which revealed a stiff and ulcerated stenosis in the ileum. Histological analysis demonstrated the presence of diffuse intestinal ganglioneuromatosis. Three years after surgery, the patient is asymptomatic, with normal haemoglobin levels. This case demonstrates an isolated form of intestinal ganglioneuromatosis, with an atypical presentation, difficult to diagnose despite an exhaustive evaluation.

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Conceived to host 5 kg of xenon at a pressure of 15 bar in the fiducial volume, the NEXT-White (NEW) apparatus is currently the largest high pressure xenon gas TPC using electroluminescent amplification in the world. It is also a 1:2 scale model of the NEXT-100 detector scheduled to start searching for ββ0ν decays in 136 Xe in 2019. Both detectors measure the energy of the event using a plane of photomultipliers located behind a transparent cathode. They can also reconstruct the trajectories of charged tracks in the dense gas of the TPC with the help of a plane of silicon photomultipliers located behind the anode. A sophisticated gas system, common to both detectors, allows the high gas purity needed to guarantee a long electron lifetime. NEXT-White has been operating since October 2017 at the Canfranc Underground Laboratory (LSC), in Spain. This paper describes the detector and associated infrastructures.

IntroductionSinistral, or left-sided, portal hypertension (SPH) is a rare entity, with multiple potential causes. Gastrointestinal variceal bleeding and hypersplenism are its’ major clinical manifestations. The main aim of the present study is to summarize the clinical features of patients with SPH.Patients and methodsThis was a retrospective analysis of consecutive patients with present or previous diagnosis of SHP, observed in a Gastroenterology Department, in a period of 2 years. Patients with clinical, radiological or laboratory alterations suggestive of cirrhosis were excluded. Causes of SPH, clinical manifestations and outcomes were registered. Potential factors associated with gastrointestinal bleeding were analyzed.ResultsIn the study period a total of 22 patients (male – 17; mean age – 59.6 ± 10.6 years) with SHP were included. Clinical manifestations were: asymptomatic/unspecific abdominal pain (n = 14); gastrointestinal bleeding (n = 8). Eleven (50%) patients had increased aminotransferases, GGT and/or alkaline phosphatase although liver function was normal in all of them. Causes of SPH were chronic pancreatitis (n = 7), acute pancreatitis (n = 7), pancreatic cancer (n = 4), pancreatic surgery (n = 3) and arteriovenous malformation (n = 1). All patients had gastric and/or esophageal varices and seven had splenomegaly. Five (22.7%) had thrombocytopenia, associated with hypersplenism. Five patients (22.7%) were submitted to endoscopic treatment and eight were submitted to splenic artery embolization and/or splenectomy. There were no cases of variceal rebleeding and two patients died. Patients without liver enzymes elevation had a higher probability of gastrointestinal bleeding (87.5% vs. 28.6%; p = 0.024).ConclusionsAcute and chronic pancreatitis are the major causes of SHP. Gastrointestinal bleeding is the most important clinical manifestation and patients without liver enzyme elevation seem more prone to bleed. Specific treatment is seldom performed or needed.