53,069 research outputs found
Cosmic Ray Physics with ACORDE at LHC
The use of large underground high-energy physics experiments, for comic ray
studies, have been used, in the past, at CERN, in order to measure, precisely,
the inclusive cosmic ray flux in the energy range from 2x10^10 - 2x10^12 eV.
ACORDE, ALICE Cosmic Rays DEtector, will act as Level 0 cosmic ray trigger and,
together with other ALICE apparatus, will provide precise information on cosmic
rays with primary energies around 10^15 - 10^17 eV. This paper reviews the main
detector features, the present status, commissioning and integration with other
apparatus. Finally, we discuss the ACORDE-ALICE cosmic ray physics program.Comment: Contribution to the 2007 Europhysics Conference on High Energy
Physics - Manchester, England 19-25 July 2007; 3 pages, 3 figure
Assessment of the worthwhileness of efficient driving in railway systems with high-receptivity power supplies
Eco-driving is one of the most important strategies for significantly reducing the energy consumption of railways with low investments. It consists of designing a way of driving a train to fulfil a target running time, consuming the minimum amount of energy. Most eco-driving energy savings come from the substitution of some braking periods with coasting periods. Nowadays, modern trains can use regenerative braking to recover the kinetic energy during deceleration phases. Therefore, if the receptivity of the railway system to regenerate energy is high, a question arises: is it worth designing eco-driving speed profiles? This paper assesses the energy benefits that eco-driving can provide in different scenarios to answer this question. Eco-driving is obtained by means of a multi-objective particle swarm optimization algorithm, combined with a detailed train simulator, to obtain realistic results. Eco-driving speed profiles are compared with a standard driving that performs the same running time. Real data from Spanish high-speed lines have been used to analyze the results in two case studies. Stretches fed by 1 Ă 25 kV and 2 Ă 25 kV AC power supply systems have been considered, as they present high receptivity to regenerate energy. Furthermore, the variations of the two most important factors that affect the regenerative energy usage have been studied: train motors efficiency ratio and catenary resistance. Results indicate that the greater the catenary resistance, the more advantageous eco-driving is. Similarly, the lower the motor efficiency, the greater the energy savings provided by efficient driving. Despite the differences observed in energy savings, the main conclusion is that eco-driving always provides significant energy savings, even in the case of the most receptive power supply network. Therefore, this paper has demonstrated that efforts in improving regenerated energy usage must not neglect the role of eco-driving in railway efficiency
Upper Energy Limit of Heavy Baryon Chiral Perturbation Theory in Neutral Pion Photoproduction
With the availability of the new neutral pion photoproduction from the proton
data from the A2 and CB-TAPS Collaborations at Mainz it is mandatory to revisit
Heavy Baryon Chiral Perturbation Theory (HBChPT) and address the extraction of
the partial waves as well as other issues such as the value of the low-energy
constants, the energy range where the calculation provides a good agreement
with the data and the impact of unitarity. We find that, within the current
experimental status, HBChPT with the fitted LECs gives a good agreement with
the existing neutral pion photoproduction data up to 170 MeV and that
imposing unitarity does not improve this picture. Above this energy the data
call for further improvement in the theory such as the explicit inclusion of
the \Delta (1232). We also find that data and multipoles can be well described
up to 185 MeV with Taylor expansions in the partial waves up to first
order in pion energy.Comment: 6 pages, 5 figures, version to be published in Physics Letters
Results on a pedagogic approach for tailoring public health interventions to minimise opportunistic infections.
We are performing curriculum modifications on the first year BSc (Hons) Biomedical Science module âBasic Microbiologyâ (De Montfort University, UK) to increase studentsâ knowledge of basic medical parasitology and infectious diseases, so these students can acquire the necessary skills to tackle their final degree module âMedical Microbiologyâ. Following student feedback on a novel short intervention in 2017/18 to promote awareness about human immunodeficiency virus (HIV), we have created an engaging workshop session to cover not only HIV but also the opportunistic infections that can affect HIV patients that have developed acquired immune deficiency syndrome (AIDS) and how to prevent them. The objective of this work was to evaluate the effectiveness of the improved workshop developed and to collect studentsâ impressions to perform further modifications if needed. Briefly, students were required to develop public health measures for HIV positive patients with two different degrees of immunosuppression (i.e. with CD4+ T cells in peripheral blood above and below 200 cells/ÎŒl) to prevent exposure and infection from opportunistic pathogens such as Cryptosporidium spp., Toxoplasma gondii or Pneumocystis jirovecii from: a) sexual exposures; b) intravenous drug use; b) environment and work; c) food and water; d) foreign travel. Students, following evidence-based public health methodology, tailored their measures or interventions using the most up-to-date information reported in the literature regarding HIV chemoprophylaxis and recent guidelines published by US Department of Health and Human Services on HIV/AIDS treatment and prevention. Interventions were critically analysed with all students in the last 20 min. of the workshop, which was repeated several times due to the number of students (n=203). The objectives of this workshop were evaluated by careful analysis of a specific feedback questionnaire (n=46 out of 203) voluntarily completed by students at the end of the workshop. The questionnaire showed the following feedback: 80.4% (65.2% agreed; 15.2% strongly agreed) indicated that they learnt how to identify public health interventions; and 95.7% (56.5% agreed; 39.1% strongly agreed) indicated that they would be able to establish measures to reduce HIV transmission and prevent opportunistic infections. Additionally, 95.7% (39.1% agreed; 56.5% strongly agreed) indicated that the workshop helped them to understand the relevance of local and global interventions. Finally, 97.8% of responders considered that the content (52.2% agreed; 45.7% strongly agreed) and duration (60.9% agreed; 37% strongly agreed) of the workshop was appropriate; and 89.1% (58.7% agreed; 30.4% strongly agreed) and 73.9% (41.3% agreed; 32.6% strongly agreed) enjoyed and were satisfied with the workshop provided, respectively. In conclusion, the improved workshop developed would seem to be effective for promoting sexual and public health education to minimise opportunistic pathogen infections in relevant patients when delivered to students with a basic knowledge of microbiology and parasitology
Neutrino flux predictions for known Galactic microquasars
It has been proposed recently that Galactic microquasars may be prodigious
emitters of TeV neutrinos that can be detected by upcoming km^2 neutrino
telescopes. In this paper we consider a sample of identified microquasars and
microquasar candiates, for which available data enables rough determination of
the jet parameters. By employing the parameters inferred from radio
observations of various jet ejection events, we determine the neutrino fluxes
that should have been produced during these events by photopion production in
the jet. Despite the large uncertainties in our analysis, we demonstrate that
in several of the sources considered, the neutrino flux at Earth, produced in
events similar to those observed, would exceed the detection threshold of a
km^2 neutrino detector. The class of microquasars may contain also sources with
bulk Lorentz factors larger than those characteristic of the sample considered
here, directed along our line of sight. Such sources, which may be very
difficult to resolve at radio wavelengths and hence may be difficult to
identify as microqusar candidates, may emit neutrinos with fluxes significantly
larger than typically obtained in the present analysis. These sources may
eventually be identified through their neutrino and gamma-ray emission.Comment: 17 pages. Submitted to Ap
Nonlinear supersymmetry: from classical to quantum mechanics
Quantization of the nonlinear supersymmetry faces a problem of a quantum
anomaly. For some classes of superpotentials, the integrals of motion admit the
corrections guaranteeing the preservation of the nonlinear supersymmetry at the
quantum level. With an example of the system realizing the nonlinear
superconformal symmetry, we discuss the nature of such corrections and
speculate on their possible general origin.Comment: 11 page
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