2,361 research outputs found

    Developments in perfect simulation of Gibbs measures through a new result for the extinction of Galton-Watson-like processes

    Full text link
    This paper deals with the problem of perfect sampling from a Gibbs measure with infinite range interactions. We present some sufficient conditions for the extinction of processes which are like supermartingales when large values are taken. This result has deep consequences on perfect simulation, showing that local modifications on the interactions of a model do not affect simulability. We also pose the question to optimize over a class of sequences of sets that influence the sufficient condition for the perfect simulation of the Gibbs measure. We completely solve this question both for the long range Ising models and for the spin models with finite range interactions.Comment: 28 page

    Splitting neutrino masses and showering into Sky

    Get PDF
    Neutrino masses might be as light as a few time the atmospheric neutrino mass splitting. High Energy ZeV cosmic neutrinos (in Z-Showering model) might hit relic ones at each mass in different resonance energies in our nearby Universe. This non-degenerated density and energy must split UHE Z-boson secondaries (in Z-Burst model) leading to multi injection of UHECR nucleons within future extreme AUGER energy. Secondaries of Z-Burst as neutral gamma, below a few tens EeV are better surviving local GZK cut-off and they might explain recent Hires BL-Lac UHECR correlations at small angles. A different high energy resonance must lead to Glashow's anti-neutrino showers while hitting electrons in matter. In air, Glashow's anti-neutrino showers lead to collimated and directional air-showers offering a new Neutrino Astronomy. At greater energy around PeV, Tau escaping mountains and Earth and decaying in flight are effectively showering in air sky. These Horizontal showering is splitting by geomagnetic field in forked shapes. Such air-showers secondaries release amplified and beamed gamma bursts (like observed TGF), made also by muon and electron pair bundles, with their accompanying rich Cherenkov flashes. Also planet' s largest (Saturn, Jupiter) atmosphere limbs offer an ideal screen for UHE GZK and Z-burst tau neutrino, because their largest sizes. Titan thick atmosphere and small radius are optimal for discovering up-going resonant Glashow resonant showers. Earth detection of Neutrino showering by twin Magic Telescopes on top mountains, or by balloons and satellites arrays facing the limbs are the simplest and cheapest way toward UHE Neutrino Astronomy .Comment: 4 pages, 7 figures; an author's name correction and Journal Referenc

    Comparison of the dietary fibre composition of old and modern durum wheat (Triticum turgidum spp. durum) genotypes

    Get PDF
    It has been suggested that intensive breeding has led to decreased contents of health-promoting components in modern wheats. We therefore compared the contents and compositions of the major dietary fibre components, arabinoxylan and β-glucan, in semolina and wholemeal flour of old and modern Italian durum wheats. No differences in total arabinoxylan content were observed but the modern varieties had higher proportions of soluble arabinoxylan in wholemeals and of β-glucan in semolina. The study therefore provides no evidence that intensive breeding has had negative effects on the contents of dietary fibre components in durum wheat. However, comparison of material grown over two years indicated that the content and composition of arabinoxylan and β-glucan were more stable in the older than in the modern genotypes. The identification of modern cultivars with high viscosity associated with a high content of β-glucan suggests that they are good sources of fibre for human health

    On the impossibility of entropy reversal, and its application to zero-knowledge proofs

    Get PDF
    Zero knowledge proof systems have been widely studied in cryptography. In the statistical setting, two classes of proof systems studied are Statistical Zero Knowledge (SZK) and Non-Interactive Statistical Zero Knowledge (NISZK), where the difference is that in NISZK only very limited communication is allowed between the verifier and the prover. It is an open problem whether these two classes are in fact equal. In this paper, we rule out efficient black box reductions between SZK and NISZK. We achieve this by studying algorithms which can reverse the entropy of a function. The problem of estimating the entropy of a circuit is complete for NISZK. Hence, reversing the entropy of a function is equivalent to a black box reduction of NISZK to its complement, which is known to be equivalent to a black box reduction of SZK to NISZK [Goldreich et al, CRYPTO 1999]. We show that any such black box algorithm incurs an exponential loss of parameters, and hence cannot be implemented efficiently

    Predictive value of clinical and laboratory features for the main febrile diseases in children living in Tanzania: A prospective observational study.

    Get PDF
    To construct evidence-based guidelines for management of febrile illness, it is essential to identify clinical predictors for the main causes of fever, either to diagnose the disease when no laboratory test is available or to better target testing when a test is available. The objective was to investigate clinical predictors of several diseases in a cohort of febrile children attending outpatient clinics in Tanzania, whose diagnoses have been established after extensive clinical and laboratory workup. From April to December 2008, 1005 consecutive children aged 2 months to 10 years with temperature ≥38°C attending two outpatient clinics in Dar es Salaam were included. Demographic characteristics, symptoms and signs, comorbidities, full blood count and liver enzyme level were investigated by bi- and multi-variate analyses (Chan, et al., 2008). To evaluate accuracy of combined predictors to construct algorithms, classification and regression tree (CART) analyses were also performed. 62 variables were studied. Between 4 and 15 significant predictors to rule in (aLR+>1) or rule out (aLR+<1) the disease were found in the multivariate analysis for the 7 more frequent outcomes. For malaria, the strongest predictor was temperature ≥40°C (aLR+8.4, 95%CI 4.7-15), for typhoid abdominal tenderness (5.9,2.5-11), for urinary tract infection (UTI) age ≥3 years (0.20,0-0.50), for radiological pneumonia abnormal chest auscultation (4.3,2.8-6.1), for acute HHV6 infection dehydration (0.18,0-0.75), for bacterial disease (any type) chest indrawing (19,8.2-60) and for viral disease (any type) jaundice (0.28,0.16-0.41). Other clinically relevant and easy to assess predictors were also found: malaria could be ruled in by recent travel, typhoid by jaundice, radiological pneumonia by very fast breathing and UTI by fever duration of ≥4 days. The CART model for malaria included temperature, travel, jaundice and hepatomegaly (sensitivity 80%, specificity 64%); typhoid: age ≥2 years, jaundice, abdominal tenderness and adenopathy (46%,93%); UTI: age <2 years, temperature ≥40°C, low weight and pale nails (20%,96%); radiological pneumonia: very fast breathing, chest indrawing and leukocytosis (38%,97%); acute HHV6 infection: less than 2 years old, (no) dehydration, (no) jaundice and (no) rash (86%,51%); bacterial disease: chest indrawing, chronic condition, temperature ≥39.7°c and fever duration >3 days (45%,83%); viral disease: runny nose, cough and age <2 years (68%,76%). A better understanding of the relative performance of these predictors might be of great help for clinicians to be able to better decide when to test, treat, refer or simply observe a sick child, in order to decrease morbidity and mortality, but also to avoid unnecessary antimicrobial prescription. These predictors have been used to construct a new algorithm for the management of childhood illnesses called ALMANACH
    corecore