Measurement of the response of heat-and-ionization germanium detectors to nuclear recoils

The heat quenching factor Q' (the ratio of the heat signals produced by nuclear and electron recoils of equal energy) of the heat-and-ionization germanium bolometers used by the EDELWEISS collaboration has been measured. It is explained how this factor affects the energy scale and the effective quenching factor observed in calibrations with neutron sources. This effective quenching effect is found to be equal to Q/Q', where Q is the quenching factor of the ionization yield. To measure Q', a precise EDELWEISS measurement of Q/Q' is combined with values of Q obtained from a review of all available measurements of this quantity in tagged neutron beam experiments. The systematic uncertainties associated with this method to evaluate Q' are discussed in detail. For recoil energies between 20 and 100 keV, the resulting heat quenching factor is Q' = 0.91+-0.03+-0.04, where the two errors are the contributions from the Q and Q/Q' measurements, respectively. The present compilation of Q values and evaluation of Q' represent one of the most precise determinations of the absolute energy scale for any detector used in direct searches for dark matter.Comment: 28 pages, 7 figures. Submitted to Phys. Rev.

The scintillation and ionization yield of liquid xenon for nuclear recoils

XENON10 is an experiment designed to directly detect particle dark matter. It is a dual phase (liquid/gas) xenon time-projection chamber with 3D position imaging. Particle interactions generate a primary scintillation signal (S1) and ionization signal (S2), which are both functions of the deposited recoil energy and the incident particle type. We present a new precision measurement of the relative scintillation yield \leff and the absolute ionization yield Q_y, for nuclear recoils in xenon. A dark matter particle is expected to deposit energy by scattering from a xenon nucleus. Knowledge of \leff is therefore crucial for establishing the energy threshold of the experiment; this in turn determines the sensitivity to particle dark matter. Our \leff measurement is in agreement with recent theoretical predictions above 15 keV nuclear recoil energy, and the energy threshold of the measurement is 4 keV. A knowledge of the ionization yield \Qy is necessary to establish the trigger threshold of the experiment. The ionization yield \Qy is measured in two ways, both in agreement with previous measurements and with a factor of 10 lower energy threshold.Comment: 8 pages, 9 figures. To be published in Nucl. Instrum. Methods

Flying ad-hoc network application scenarios and mobility models

[EN] Flying ad-hoc networks are becoming a promising solution for different application scenarios involving unmanned aerial vehicles, like urban surveillance or search and rescue missions. However, such networks present various and very specific communication issues. As a consequence, there are several research studies focused on analyzing their performance via simulation. Correctly modeling mobility is crucial in this context and although many mobility models are already available to reproduce the behavior of mobile nodes in an ad-hoc network, most of these models cannot be used to reliably simulate the motion of unmanned aerial vehicles. In this article, we list the existing mobility models and provide guidance to understand whether they could be actually adopted depending on the specific flying ad-hoc network application scenarios, while discussing their advantages and disadvantages.Bujari, A.; Tavares De Araujo Cesariny Calafate, CM.; Cano, J.; Manzoni, P.; Palazzi, CE.; Ronzani, D. (2017). Flying ad-hoc network application scenarios and mobility models. International Journal of Distributed Sensor Networks. 13(10):1-17. doi:10.1177/1550147717738192S117131

Diagnostic value of biochemical markers (FibroTest-FibroSURE) for the prediction of liver fibrosis in patients with non-alcoholic fatty liver disease

BACKGROUND: Liver biopsy is considered as the gold standard for assessing non-alcoholic fatty liver disease (NAFLD) histologic lesions. The aim of this study was to determine the diagnostic utility of non-invasive markers of fibrosis, validated in chronic viral hepatitis and alcoholic liver disease (FibroTest, FT), in patients with NAFLD. METHODS: 170 patients with suspected NAFLD were prospectively included in a reference center (Group 1), 97 in a multicenter study (Group 2) and 954 blood donors as controls. Fibrosis was assessed on a 5 stage histological scale validated by Kleiner et al from F0 = none, F1 = perisinusoidal or periportal, F2 = perisinusoidal and portal/periportal, F3 = bridging and F4 = cirrhosis. Histology and the biochemical measurements were blinded to any other characteristics. The area under the ROC curves (AUROC), sensitivity (Se), specificity (Sp), positive and negative predictive values (PPV, NPV) were assessed. RESULTS: In both groups FT has elevated and not different AUROCs for the diagnosis of advanced fibrosis (F2F3F4): 0.86 (95%CI 0.77–0.91) versus 0.75 (95%CI 0.61–0.83; P = 0.10), and for F3F4: 0.92 (95%CI 0.83–0.96) versus 0.81 (95%CI 0.64–0.91; P = 0.12) in Group1 and Group 2 respectively. When the 2 groups were pooled together a FT cutoff of 0.30 had a 90% NPV for advanced fibrosis (Se 77%); a FT cutoff of 0.70 had a 73% PPV for advanced fibrosis (Sp 98%). CONCLUSION: In patients with NAFLD, FibroTest, a simple and non-invasive quantitative estimate of liver fibrosis reliably predicts advanced fibrosis

Applicability and precautions of use of liver injury biomarker FibroTest. A reappraisal at 7 years of age

<p>Abstract</p> <p>Background</p> <p>FibroTest (FT) is a validated biomarker of fibrosis. To assess the applicability rate and to reduce the risk of false positives/negatives (RFPN), security algorithms were developed. The aims were to estimate the prevalence of RFPN and of proven failures, and to identify factors associated with their occurrences.</p> <p>Methods</p> <p>Four populations were studied: 954 blood donors (P1), 7,494 healthy volunteers (P2), 345,695 consecutive worldwide sera (P3), including 24,872 sera analyzed in a tertiary care centre (GHPS) (P4). Analytical procedures of laboratories with RFPN > 5% and charts of P4 patients in with RFPN were reviewed.</p> <p>Results</p> <p>The prevalence of RFPN was 0.52% (5/954; 95%CI 0.17-1.22) in P1, 0.51% (38/7494; 0.36-0.70) in P2, and 0.97% (3349/345695; 0.94-1.00) in P3. Three a priori high-risk populations were confirmed: 1.97% in P4, 1.77% in HIV centre and 2.61% in Sub-Saharan origin subjects. RFPN was mostly associated with low haptoglobin (0.46%), and high apolipoproteinA1 (0.21%). A traceability study of a P3 laboratory with RFPFN > 5% permitted to correct analytical procedures.</p> <p>Conclusion</p> <p>The mean applicability rate of Fibrotest was 99.03%. Independent factors associated with the high risk of false positives/negatives were HIV center, subSaharan origin, and a tertiary care reference centre, although the applicability rate remained above 97%.</p

Diagnostic value of biochemical markers (NashTest) for the prediction of non alcoholo steato hepatitis in patients with non-alcoholic fatty liver disease

BACKGROUND: Liver biopsy is considered the gold standard for assessing histologic lesions of non-alcoholic fatty liver disease (NAFLD). The aim was to develop and validate a new biomarker of non alcoholic steato hepatitis (NASH) the NashTest (NT) in patients with NAFLD. METHODS: 160 patients with NAFLD were prospectively included in a training group, 97 were included in a multicenter validation group and 383 controls. Histological diagnoses used Kleiner et al's scoring system, with 3 classes for NASH: "Not NASH", "Borderline", "NASH"). The area under the ROC curves (AUROC), sensitivity (Se), specificity (Sp), and positive and negative predictive values (PPV, NPV) were assessed. RESULTS: NT was developed using patented algorithms combining 13 parameters: age, sex, height, weight, and serum levels of triglycerides, cholesterol, alpha2macroglobulin, apolipoprotein A1, haptoglobin, gamma-glutamyl-transpeptidase, transaminases ALT, AST, and total bilirubin. AUROCs of NT for the diagnosis of NASH in the training and validation groups were, respectively, 0.79 (95%CI 0.69–0.86) and 0.79 (95%CI 0.67–0.87; P = 0.94); for the diagnosis of borderline NASH they were: 0.69 (95%CI 0.60–0.77) and 0.69 (95%CI 0.57–0.78; P = 0.98) and for the diagnosis of no NASH, 0.77 (95%CI 0.68–0.84) and 0.83 (95%CI 0.67–0.90; P = 0.34). When the two groups were pooled together the NashTest Sp for NASH = 94% (PPV = 66%), and Se = 33% (NPV = 81%); for borderline NASH or NASH Sp = 50% (PPV = 74%) and Se = 88% (NPV = 72%). CONCLUSION: In patients with non-alcoholic fatty liver disease, NashTest, a simple and non-invasive biomarker reliably predicts the presence or absence of NASH

An Accurate Definition of the Status of Inactive Hepatitis B Virus Carrier by a Combination of Biomarkers (FibroTest-ActiTest) and Viral Load

BACKGROUND: The combination of transaminases (ALT), biopsy, HBeAg and viral load have classically defined the inactive status of carriers of chronic hepatitis B. The use of FibroTest (FT) and ActiTest (AT), biomarkers of fibrosis and necroinflammatory activity, has been previously validated as alternatives to biopsy. We compared the 4-year prognostic value of combining FT-AT and viral load for a better definition of the inactive carrier status. METHODS AND FINDINGS: 1,300 consecutive CHB patients who had been prospectively followed since 2001 were pre-included. The main endpoint was the absence of liver-related complications, transplantation or death. We used the manufacturers' definitions of normal FT (< = 0.27), normal AT (< = 0.29) and 3 standard classes for viral load. The adjustment factors were age, sex, HBeAg, ethnic origin, alcohol consumption, HIV-Delta-HCV co-infections and treatment. RESULTS: 1,074 patients with baseline FT-AT and viral load were included: 41 years old, 47% African, 27% Asian, 26% Caucasian. At 4 years follow-up, 50 complications occurred (survival without complications 93.4%), 36 deaths occurred (survival 95.0%), including 27 related to HBV (survival 96.1%). The prognostic value of FT was higher than those of viral load or ALT when compared using area under the ROC curves [0.89 (95%CI 0.84-0.93) vs 0.64 (0.55-0.71) vs 0.53 (0.46-0.60) all P<0.001], survival curves and multivariate Cox model [regression coefficient 5.2 (3.5-6.9; P<0.001) vs 0.53 (0.15-0.92; P = 0.007) vs -0.001 (-0.003-0.000;P = 0.052)] respectively. A new definition of inactive carriers was proposed with an algorithm combining "zero" scores for FT-AT (F0 and A0) and viral load classes. This new algorithm provides a 100% negative predictive value for the prediction of liver related complications or death. Among the 275 patients with the classic definition of inactive carrier, 62 (23%) had fibrosis presumed with FT, and 3 died or had complications at 4 year. CONCLUSION: In patients with chronic hepatitis B, a combination of FibroTest-ActiTest and viral load testing accurately defined the prognosis and the inactive carrier status

An improved energy-efficient routing protocol based on Minimum Spanning Tree for Wireless Sensor Network

International audienc