1,404 research outputs found

    Development of a parallel trigger framework for rare decay searches

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    L'esperimento NA62 rappresenta il programma attuale di test del Modello Standard mediante lo studio del mesone K al CERN di Ginevra e offre un approccio complementare rispetto agli esperimenti alla frontiera delle alte energie al Large Hadron Collider. L'obiettivo dell'esperimento NA62 Ăš misurare il rapporto di decadimento per il processo K + → π+ Îœ Îœ con una precisione del ∌10%. Essendo il valore previsto dal Modello Standard determinato con elevata precisione, la misura di questa quantitĂ  risulta essere un ottimo modo per investigare l'esistenza di nuova Fisica. In modo complementare a questo programma principale, la semplicitĂ  dei decadimenti del mesone K + (pochi canali di decadimento e bassa molteplicitĂ  nello stato finale), offre la possibilitĂ  di raggiungere ottime sensibilitĂ  nelle ricerche di decadimenti che violano la conservazione del sapore leptonico. Le caratteristiche sperimentali di decadimenti come K + → π- ÎŒ+ÎŒ+ sono molto chiare e permettono una efficace reiezione del fondo. Tuttavia, per misurare eventi di questo tipo Ăš necessario produrre un numero considerevole di decadimenti del mesone K + . La banda in scrittura su disco rigido o nastro magnetico disponibile attualmente non consente la memorizzazione di tutti gli eventi prodotti e risulta necessaria una selezione a piĂč stadi degli eventi potenzialmente interessanti (trigger). In NA62, una prima selezione viene effettuata in tempo reale (tempi di risposta inferiori ad 1ms) dal cosiddetto trigger di livello 0, basato su logica programmabile (FPGA), che non permette la stessa flessibilitĂ  dei processori utilizzati per i calcolatori programmabili utilizzando software. Le prestazioni delle architetture parallele come le CPU multi-core e le GPU (Graphics Processing Unit) presenti sulle schede grafiche dei calcolatori, sono promettenti per un eventuale utilizzo di queste piattaforme per il riconoscimento di patterns piĂč elaborati come ad esempio la ricostruzione di circonferenze, dovute a luce Čerenkov, all'interno del rivelatore RICH di NA62. Nella prima parte della mia tesi ho effettuato uno studio di fattibilitĂ  sulla possibilitĂ  di utilizzare le GPU in un contesto di alta banda di eventi e bassa latenza, quale quello del trigger in tempo reale. A NA62 questo studio ha richiesto lo sviluppo di algoritmi paralleli diversi e sempre piĂč complessi, per determinare le prestazioni e trovare i possibili colli di bottiglia di un sistema di questo tipo. Descrivo poi lo sviluppo di un framework software ad alte prestazioni, che utilizza tecniche di programmazione multithreaded e drivers di rete veloci per il trasporto delle primitive di trigger dall'elettronica di front end alla memoria della GPU per l'elaborazione e la selezione degli eventi. Infine, Ăš descritto l'utilizzo del sistema sviluppato per la selezione di decadimenti K + → π- ÎŒ+ÎŒ+ tramite l'impiego di un algoritmo per il riconoscimento di piĂč anelli nel rivelatore RICH. Al fine di determinare l'efficienza di selezione del decadimento ho studiato l'efficienza di reiezione del fondo e l'accettanza per gli eventi di segnale al variare di alcuni parametri di selezione, determinando i vantaggi di questo approccio innovativo

    Heterogeneous reconstruction of tracks and primary vertices with the CMS pixel tracker

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    The High-Luminosity upgrade of the LHC will see the accelerator reach an instantaneous luminosity of 7×1034cm−2s−17\times 10^{34} cm^{-2}s^{-1} with an average pileup of 200200 proton-proton collisions. These conditions will pose an unprecedented challenge to the online and offline reconstruction software developed by the experiments. The computational complexity will exceed by far the expected increase in processing power for conventional CPUs, demanding an alternative approach. Industry and High-Performance Computing (HPC) centres are successfully using heterogeneous computing platforms to achieve higher throughput and better energy efficiency by matching each job to the most appropriate architecture. In this paper we will describe the results of a heterogeneous implementation of pixel tracks and vertices reconstruction chain on Graphics Processing Units (GPUs). The framework has been designed and developed to be integrated in the CMS reconstruction software, CMSSW. The speed up achieved by leveraging GPUs allows for more complex algorithms to be executed, obtaining better physics output and a higher throughput

    NaNet:a low-latency NIC enabling GPU-based, real-time low level trigger systems

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    We implemented the NaNet FPGA-based PCI2 Gen2 GbE/APElink NIC, featuring GPUDirect RDMA capabilities and UDP protocol management offloading. NaNet is able to receive a UDP input data stream from its GbE interface and redirect it, without any intermediate buffering or CPU intervention, to the memory of a Fermi/Kepler GPU hosted on the same PCIe bus, provided that the two devices share the same upstream root complex. Synthetic benchmarks for latency and bandwidth are presented. We describe how NaNet can be employed in the prototype of the GPU-based RICH low-level trigger processor of the NA62 CERN experiment, to implement the data link between the TEL62 readout boards and the low level trigger processor. Results for the throughput and latency of the integrated system are presented and discussed.Comment: Proceedings for the 20th International Conference on Computing in High Energy and Nuclear Physics (CHEP

    Irreversible AE1 tyrosine phosphorylation leads to membrane vesiculation in G6PD deficient red cells

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    Background. While G6PD deficiency is one of the major causes of acute hemolytic anemia, the membrane changes leading to red cell lysis have not been extensively studied. New findings concerning the mechanisms of G6PD deficient red cell destruction may facilitate our understanding of the large individual variations in susceptibility to pro-oxidant compounds and aid the prediction of the hemolytic activity of new drugs. Methodology/Principal Findings. Our results show that treatment of G6PD deficient red cells with diamide (0.25 mM) or divicine (0.5 mM) causes: (1) an increase in the oxidation and tyrosine phosphorylation of AE1; (2) progressive recruitment of phosphorylated AE1 in large membrane complexes which also contain hemichromes; (3) parallel red cell lysis and a massive release of vesicles containing hemichromes. We have observed that inhibition of AE1 phosphorylation by Syk kinase inhibitors prevented its clustering and the membrane vesiculation while increases in AE1 phosphorylation by tyrosine phosphatase inhibitors increased both red cell lysis and vesiculation rates. In control RBCs we observed only transient AE1 phosphorylation. Conclusions/Significance. Collectively, our findings indicate that persistent tyrosine phosphorylation produces extensive membrane destabilization leading to the loss of vesicles which contain hemichromes. The proposed mechanism of hemolysis may be applied to other hemolytic diseases characterized by the accumulation of hemoglobin denaturation products

    Risk factors associated with adverse fetal outcomes in pregnancies affected by Coronavirus disease 2019 (COVID-19): a secondary analysis of the WAPM study on COVID-19.

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    Objectives To evaluate the strength of association between maternal and pregnancy characteristics and the risk of adverse perinatal outcomes in pregnancies with laboratory confirmed COVID-19. Methods Secondary analysis of a multinational, cohort study on all consecutive pregnant women with laboratory-confirmed COVID-19 from February 1, 2020 to April 30, 2020 from 73 centers from 22 different countries. A confirmed case of COVID-19 was defined as a positive result on real-time reverse-transcriptase-polymerase-chain-reaction (RT-PCR) assay of nasal and pharyngeal swab specimens. The primary outcome was a composite adverse fetal outcome, defined as the presence of either abortion (pregnancy loss before 22 weeks of gestations), stillbirth (intrauterine fetal death after 22 weeks of gestation), neonatal death (death of a live-born infant within the first 28 days of life), and perinatal death (either stillbirth or neonatal death). Logistic regression analysis was performed to evaluate parameters independently associated with the primary outcome. Logistic regression was reported as odds ratio (OR) with 95% confidence interval (CI). Results Mean gestational age at diagnosis was 30.6+/-9.5 weeks, with 8.0% of women being diagnosed in the first, 22.2% in the second and 69.8% in the third trimester of pregnancy. There were six miscarriage (2.3%), six intrauterine device (IUD) (2.3) and 5 (2.0%) neonatal deaths, with an overall rate of perinatal death of 4.2% (11/265), thus resulting into 17 cases experiencing and 226 not experiencing composite adverse fetal outcome. Neither stillbirths nor neonatal deaths had congenital anomalies found at antenatal or postnatal evaluation. Furthermore, none of the cases experiencing IUD had signs of impending demise at arterial or venous Doppler. Neonatal deaths were all considered as prematurity-related adverse events. Of the 250 live-born neonates, one (0.4%) was found positive at RT-PCR pharyngeal swabs performed after delivery. The mother was tested positive during the third trimester of pregnancy. The newborn was asymptomatic and had negative RT-PCR test after 14 days of life. At logistic regression analysis, gestational age at diagnosis (OR: 0.85, 95% CI 0.8-0.9 per week increase; pPeer reviewe

    Maternal and perinatal outcomes of pregnant women with SARS-CoV-2 infection

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    Objectives To evaluate the maternal and perinatal outcomes of pregnancies affected by SARS-CoV-2 infection. Methods This was a multinational retrospective cohort study including women with a singleton pregnancy and laboratory-confirmed SARS-CoV-2 infection, conducted in 72 centers in 22 different countries in Europe, the USA, South America, Asia and Australia, between 1 February 2020 and 30 April 2020. Confirmed SARS-CoV-2 infection was defined as a positive result on real-time reverse-transcription polymerase chain reaction (RT-PCR) assay of nasopharyngeal swab specimens. The primary outcome was a composite measure of maternal mortality and morbidity, including admission to the intensive care unit (ICU), use of mechanical ventilation and death. Results In total, 388 women with a singleton pregnancy tested positive for SARS-CoV-2 on RT-PCR of a nasopharyngeal swab and were included in the study. Composite adverse maternal outcome was observed in 47/388 (12.1%) women; 43 (11.1%) women were admitted to the ICU, 36 (9.3%) required mechanical ventilation and three (0.8%) died. Of the 388 women included in the study, 122 (31.4%) were still pregnant at the time of data analysis. Among the other 266 women, six (19.4% of the 31 women with first-trimester infection) had miscarriage, three (1.1%) had termination of pregnancy, six (2.3%) had stillbirth and 251 (94.4%) delivered a liveborn infant. The rate of preterm birth before 37 weeks' gestation was 26.3% (70/266). Of the 251 liveborn infants, 69/251(27.5%) were admitted to the neonatal ICU, and there were five (2.0%) neonatal deaths. The overall rate of perinatal death was 4.1% (11/266). Only one (1/251, 0.4%) infant, born to a mother who tested positive during the third trimester, was found to be positive for SARS-CoV-2 on RT-PCR. Conclusions SARS-CoV-2 infection in pregnant women is associated with a 0.8% rate of maternal mortality, but an 11.1% rate of admission to the ICU. The risk of vertical transmission seems to be negligible. (C) 2020 International Society of Ultrasound in Obstetrics and Gynecology.Peer reviewe

    Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

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    Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð„with constraintsð ð ð„ „ ðandðŽð„ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

    Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks