1,412 research outputs found
Discrete Abelian Gauge Theories for Quantum Simulations of QED
We study a lattice gauge theory in Wilson's Hamiltonian formalism. In view of
the realization of a quantum simulator for QED in one dimension, we introduce
an Abelian model with a discrete gauge symmetry , approximating
the theory for large . We analyze the role of the finiteness of the
gauge fields and the properties of physical states, that satisfy a generalized
Gauss's law. We finally discuss a possible implementation strategy, that
involves an effective dynamics in physical space.Comment: 13 pages, 3 figure
Nuclear Emulsion Film Detectors for Proton Radiography: Design and Test of the First Prototype
Proton therapy is nowadays becoming a wide spread clinical practice in cancer
therapy and sophisticated treatment planning systems are routinely used to
exploit at best the ballistic properties of charged particles. The information
on the quality of the beams and the range of the protons is a key issue for the
optimization of the treatment. For this purpose, proton radiography can be used
in proton therapy to obtain direct information on the range of the protons, on
the average density of the tissues for treatment planning optimization and to
perform imaging with negligible dose to the patient. We propose an innovative
method based on nuclear emulsion film detectors for proton radiography, a
technique in which images are obtained by measuring the position and the
residual range of protons passing through the patient's body. Nuclear emulsion
films interleaved with tissue equivalent absorbers can be fruitfully used to
reconstruct proton tracks with very high precision. The first prototype of a
nuclear emulsion based detector has been conceived, constructed and tested with
a therapeutic proton beam at PSI. The scanning of the emulsions has been
performed at LHEP in Bern, where a fully automated microscopic scanning
technology has been developed for the OPERA experiment on neutrino
oscillations. After track reconstruction, the first promising experimental
results have been obtained by imaging a simple phantom made of PMMA with a step
of 1 cm. A second phantom with five 5 x 5 mm^2 section aluminum rods located at
different distances and embedded in a PMMA structure has been also imaged.
Further investigations are in progress to improve the resolution and to image
more sophisticated phantoms.Comment: Presented at the 11th ICATPP Conference on Astroparticle, Particle,
Space Physics, Detectors and Medical Physics Applications, Como (Italy),
October 200
Dynamical versus static imperfections in quantum computers(6) Approaches from mathematical science and quantum information, Chaos and Nonlinear Dynamics in Quantum-Mechanical and Macroscopic Systems)
この論文は国立情報学研究所の電子図書館事業により電子化されました。We study the effects of imperfections in a spin model of a quantum computer. We identify different regimes, ranging from low-frequency fluctuations, where the imperfections can be considered static, to the high-frequency case, where the imperfections are purely dynamical and their effects are shown to be completely wiped out
Real-Life Assessment of the Ability of an Ultraviolet C Lamp (SanificaAria 200, Beghelli) to Inactivate Airborne Microorganisms in a Healthcare Environment
Airborne-mediated microbial diseases represent one of the major challenges to public health. Ultraviolet C radiation (UVC) is among the different sanitation techniques useful to reduce the risk of infection in healthcare facilities. Previous studies about the germicidal activity of UVC were mainly performed in artificial settings or in vitro models. This study aimed to assess the sanitizing effectiveness of a UVC device (SanificaAria 200, Beghelli, Valsamoggia, Bologna, Italy) in 'real-life' conditions by evaluating its ability to reduce microbial loads in several hospital settings during routine daily activities. The efficacy of the UVC lamp in reducing the bacterial component was evaluated by microbial culture through the collection of air samples in different healthcare settings at different times (30 min-24 h) after turning on the device. To assess the anti-viral activity, air samplings were carried out in a room where a SARS-CoV-2-positive subject was present. The UVC device showed good antibacterial properties against a wide range of microbial species after 6 h of activity. It was effective against possible multi-drug resistant microorganisms (e.g., Pseudomonas spp., Acinetobacter spp.) and spore-forming bacteria (e.g., Bacillus spp.). In addition, the UVC lamp was able to inactivate SARS-CoV-2 in just one hour. Thanks to its effectiveness and safety, SanificaAria 200 could be useful to inactivate airborne pathogens and reduce health risks
Infertility Worldwide: The Lack of Global Pediatric Andrologists and Prevention
Andrology is the medical specialty dealing with men’s health and reproductive system, including the genital, hormonal, reproductive, sexual, as well as psychological aspects, from birth to adulthood. Regular andrological checkups are essential both to reveal possible problems and to receive thorough advice and information so as to ensure that sexual and reproductive functions are well preserved. Estimates report that about one in three males suffers from andrological diseases, their rates varying according to the age: 27–30% of pediatric male subjects have reproductive and/or sexual conditions. In adulthood, 40% of men are affected by andrological diseases, in particular infertility and sexual problems. We studied medical literature about infertility, its prevention, and its treatment; our outcomes were to evaluate the role of research to prevent infertility especially in pediatric and adolescent age. The analysis of the data shows that in absolute numbers, the conditions directly associated with infertility are less studied than the treatment with medically assisted procreation. This research is intended as a warning to the countries worldwide: all those involved in the pediatric treatment area should be stimulated to act toward this goal, and each country should bear the responsibility of promoting and financing andrological screening campaigns
Data Flooding against Ransomware: Concepts and Implementations
Ransomware is one of the most infamous kinds of malware, particularly the “crypto” subclass, which encrypts users’ files, asking for some monetary ransom in exchange for the decryption key. Recently, crypto-ransomware grew into a scourge for enterprises and governmental institutions. The most recent and impactful cases include an oil company in the US, an international Danish shipping company, and many hospitals and health departments in Europe. Attacks result in production lockdowns, shipping delays, and even risks to human lives. To contrast ransomware attacks (crypto, in particular), we propose a family of solutions, called Data Flooding against Ransomware, tackling the main phases of detection, mitigation, and restoration, based on a mix of honeypots, resource contention, and moving target defence. These solutions hinge on detecting and contrasting the action of ransomware by flooding specific locations (e.g., the attack location, sensible folders, etc.) of the victim’s disk with files. Besides the abstract definition of this family of solutions, we present an open-source tool that implements the mitigation and restoration phases, called Ranflood. In particular, Ranflood supports three flooding strategies, apt for different attack scenarios. At its core, Ranflood buys time for the user to counteract the attack, e.g., to access an unresponsive, attacked server and shut it down manually. We benchmark the efficacy of Ranflood by performing a thorough evaluation over 6 crypto-ransomware (e.g., WannaCry, LockBit) for a total of 78 different attack scenarios, showing that Ranflood consistently lowers the amount of files lost to encryption
Local-spin-density functional for multideterminant density functional theory
Based on exact limits and quantum Monte Carlo simulations, we obtain, at any
density and spin polarization, an accurate estimate for the energy of a
modified homogeneous electron gas where electrons repel each other only with a
long-range coulombic tail. This allows us to construct an analytic
local-spin-density exchange-correlation functional appropriate to new,
multideterminantal versions of the density functional theory, where quantum
chemistry and approximate exchange-correlation functionals are combined to
optimally describe both long- and short-range electron correlations.Comment: revised version, ti appear in PR
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