1,592 research outputs found
Measurement of air and nitrogen fluorescence light yields induced by electron beam for UHECR experiments
Most of the Ultra High Energy Cosmic Ray (UHECR) experiments and projects
(HiRes, AUGER, TA, EUSO, TUS,...) use air fluorescence to detect and measure
extensive air showers (EAS). The precise knowledge of the Fluorescence Light
Yield (FLY) is of paramount importance for the reconstruction of UHECR. The
MACFLY - Measurement of Air Cherenkov and Fluorescence Light Yield - experiment
has been designed to perform such FLY measurements. In this paper we will
present the results of FLY in the 290-440 nm wavelength range for dry air and
pure nitrogen, both excited by electrons with energy of 1.5 MeV, 20 GeV and 50
GeV. The experiment uses a 90Sr radioactive source for low energy measurement
and a CERN SPS electron beam for high energy. We find that the FLY is
proportional to the deposited energy (E_d) in the gas and we show that the air
fluorescence properties remain constant independently of the electron energy.
At the reference point: atmospheric dry air at 1013 hPa and 23C, the ratio
FLY/E_d=17.6 photon/MeV with a systematic error of 13.2%.Comment: 19 pages, 8 figures. Accepted for publication in Astroparticle
Physic
Acting together: ensemble as a democratic process in art and life
Traditionally drama in schools has been seen either as a learning medium with a wide range of curricular uses or as a subject in its own right. This paper argues that the importance of drama in schools is in the processes of social and artistic engagement and experiencing of drama rather than in its outcomes. The paper contrasts the pro-social emphasis in the ensemble model of drama with the pro-technical and limited range of learning in subject-based approaches which foreground technical knowledge of periods, plays, styles and genres. The ensemble-based approach is positioned in the context of professional theatre understandings of ensemble artistry and in the context of revolutionary shifts from the pro-technical to the pro-social in educational and cultural policy making in England. Using ideas drawn from McGrath and Castoriadis, the paper claims that the ensemble approach provides young people with a model of democratic living
Millennial-Scale Climate Variability during the Last Glacial Period in the Tropical Andes
Millennial-scale climate variation during the Last Glacial period is evident in many locations worldwide, but it is unclear if such variation occurred in the interior of tropical South America, and, if so, how the low-latitude variation was related to its high-latitude counterpart. A high-resolution record, derived from the deep drilling of sediments on the floor of Lake Titicaca in the southern tropical Andes, is presented that shows clear evidence of millennial-scale climate variation between ~60 and 20 ka BP. This variation is manifested by alternations of two interbedded sedimentary units. The two units have distinctive sedimentary, geochemical, and paleobiotic properties that are controlled by the relative abundance of terrigenous or nearshore components versus pelagic components. The sediments of more terrigenous or nearshore nature likely were deposited during regionally wetter climates when river transport of water and sediment was higher, whereas the sediments of more pelagic character were deposited during somewhat drier climates regionally. The majority of the wet periods inferred from the Lake Titicaca sediment record are correlated with the cold events in the Greenland ice cores and North Atlantic sediment cores, indicating that increased intensity of the South American summer monsoon was part of near-global scale climate excursions
Global ocean cooling of 2.3°C during the Last Glacial Maximum
Quantitative constraints on past mean ocean temperature (MOT) critically inform our historical understanding of Earth's energy balance. A recently developed MOT proxy based on paleoatmospheric Xe, Kr, and N2 ratios in ice core air bubbles is a promising tool rooted in the temperature dependences of gas solubilities. However, these inert gases are systematically undersaturated in the modern ocean interior, and it remains unclear how air-sea disequilibrium may have changed in the past. Here, we carry out 30 tracer-enabled model simulations under varying circulation, sea ice cover, and wind stress regimes to evaluate air-sea disequilibrium in the Last Glacial Maximum (LGM) ocean. We find that undersaturation of all three gases was likely reduced, primarily due to strengthened high-latitude winds, biasing reconstructed MOT by −0.38 ± 0.37°C (1σ). Accounting for air-sea disequilibrium, paleoatmospheric inert gases indicate that LGM MOT was 2.27 ± 0.46°C (1σ) colder than the pre-industrial era
Operation of a 1-Liter-Volume Gaseous Argon Scintillation Counter
We have built a gas-phase argon ionization detector to measure small nuclear
recoil energies (< 10 keVee). In this paper, we describe the detector response
to X-ray and gamma calibration sources, including analysis of pulse shapes,
software triggers, optimization of gas content, and energy- and
position-dependence of the signal. We compare our experimental results against
simulation using a 5.9-keV X-ray source, as well as higher-energy gamma sources
up to 1332 keV. We conclude with a description of the detector, DAQ, and
software settings optimized for a measurement of the low-energy nuclear
quenching factor in gaseous argon. This work was performed under the auspices
of the U.S. Department of Energy by Lawrence Livermore National Laboratory in
part under Contract W-7405-Eng-48 and in part under Contract DE-AC52-07NA27344.
Funded by Lab-wide LDRD. LLNL-JRNL-415990-DRAFT.Comment: 29 pages, single-column, double-spaced, 21 figure
Maximizing the Benefit-Cost Ratio of Anthracyclines in Metastatic Breast Cancer: Case Report of a Patient with a Complete Response to High-Dose Doxorubicin
Despite the clinical efficacy of anthracycline agents such as doxorubicin, dose-limiting cardiac toxicities significantly limit their long-term use. Here, we present the case of a 33-year-old female patient with extensive metastatic ER+/PR+/HER2– mucinous adenocarcinoma of the breast, who was started on doxorubicin/cyclophosphamide therapy after progressing on paclitaxel and ovarian suppressor goserelin with aromatase inhibitor exemestane. The patient was comanaged by cardiology, who carefully monitored measures of cardiac function, including EKGs, serial echocardiograms, and profiling of lipids, troponin, and pro-BNP every 2 months. The patient was treated with the cardioprotective agent dexrazoxane, and changes in cardiac markers [e.g. decreases in ejection fraction (EF)] were immediately addressed by therapeutic intervention with the ACE inhibitor lisinopril and beta-blocker metoprolol. The patient had a complete response to doxorubicin therapy, with a cumulative dose of 1,350 mg/m2, which is significantly above the recommended limits, and to our knowledge, the highest dose reported in literature. Two and a half years after the last doxorubicin cycle, the patient is asymptomatic with no cardiotoxicity and an excellent quality of life. This case highlights the importance of careful monitoring and management of doxorubicin-mediated cardiotoxicity, and that higher cumulative doses of anthracyclines can be considered in patients with ongoing clinical benefit
Early Deglaciation in the Tropical Andes
Analysis of sediment records from lakes located beyond the glacial limit in the Andes has provided, for the first time, an independent assessment of effective moisture ( precipitation minus evaporation) and the timing of the last glaciation (1). Conditions were wet at the LGM and remained so until approximately 15,000 cal yr B.P. (2). However, deglaciation was under way from the LGM between 22,000 and 19,500 cal yr B.P., which reinforces the observation that deglaciation in the tropical Andes was primarily forced by an increase in mean annual temperature during a wet postglacial interval (3, 4)
Early Deglaciation in the Tropical Andes
Analysis of sediment records from lakes located beyond the glacial limit in the Andes has provided, for the first time, an independent assessment of effective moisture ( precipitation minus evaporation) and the timing of the last glaciation (1). Conditions were wet at the LGM and remained so until approximately 15,000 cal yr B.P. (2). However, deglaciation was under way from the LGM between 22,000 and 19,500 cal yr B.P., which reinforces the observation that deglaciation in the tropical Andes was primarily forced by an increase in mean annual temperature during a wet postglacial interval (3, 4)
Fertility, Living Arrangements, Care and Mobility
There are four main interconnecting themes around which the contributions in this book are based. This introductory chapter aims to establish the broad context for the chapters that follow by discussing each of the themes. It does so by setting these themes within the overarching demographic challenge of the twenty-first century – demographic ageing. Each chapter is introduced in the context of the specific theme to which it primarily relates and there is a summary of the data sets used by the contributors to illustrate the wide range of cross-sectional and longitudinal data analysed
Electron-based crystalline undulator
We discuss the features of a crystalline undulator of the novel type based on
the effect of a planar channeling of ultra-relativistic electrons in a
periodically bent crystals. It is demonstrated that an electron-based undulator
is feasible in the tens of GeV range of the beam energies, which is noticeably
higher than the energy interval allowed in a positron-based undulator.
Numerical analysis of the main parameters of the undulator as well as the
characteristics of the emitted undulator radiation is carried out for 20 and 50
GeV electrons channeling in diamond and silicon crystals along the (111)
crystallographic planes.Comment: 16 pages, 8 figures, Latex, IOP styl
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