3,161 research outputs found
Development of a Detector Control System for the ATLAS Pixel Detector
The innermost part of the ATLAS experiment will be a pixel detector
containing around 1750 individual detector modules. A detector control system
(DCS) is required to handle thousands of I/O channels with varying
characteristics. The main building blocks of the pixel DCS are the cooling
system, the power supplies and the thermal interlock system, responsible for
the ultimate safety of the pixel sensors. The ATLAS Embedded Local Monitor
Board (ELMB), a multi purpose front end I/O system with a CAN interface, is
foreseen for several monitoring and control tasks. The Supervisory, Control And
Data Acquisition (SCADA) system will use PVSS, a commercial software product
chosen for the CERN LHC experiments. We report on the status of the different
building blocks of the ATLAS pixel DCS.Comment: 3 pages, 2 figures, ICALEPCS 200
The Optimal Single Copy Measurement for the Hidden Subgroup Problem
The optimization of measurements for the state distinction problem has
recently been applied to the theory of quantum algorithms with considerable
successes, including efficient new quantum algorithms for the non-abelian
hidden subgroup problem. Previous work has identified the optimal single copy
measurement for the hidden subgroup problem over abelian groups as well as for
the non-abelian problem in the setting where the subgroups are restricted to be
all conjugate to each other. Here we describe the optimal single copy
measurement for the hidden subgroup problem when all of the subgroups of the
group are given with equal a priori probability. The optimal measurement is
seen to be a hybrid of the two previously discovered single copy optimal
measurements for the hidden subgroup problem.Comment: 8 pages. Error in main proof fixe
Including Systematic Uncertainties in Confidence Interval Construction for Poisson Statistics
One way to incorporate systematic uncertainties into the calculation of
confidence intervals is by integrating over probability density functions
parametrizing the uncertainties. In this note we present a development of this
method which takes into account uncertainties in the prediction of background
processes, uncertainties in the signal detection efficiency and background
efficiency and allows for a correlation between the signal and background
detection efficiencies. We implement this method with the Feldman & Cousins
unified approach with and without conditioning. We present studies of coverage
for the Feldman & Cousins and Neyman ordering schemes. In particular, we
present two different types of coverage tests for the case where systematic
uncertainties are included. To illustrate the method we show the relative
effect of including systematic uncertainties the case of dark matter search as
performed by modern neutrino tel escopes.Comment: 23 pages, 10 figures, replaced to match published versio
An Introduction to Quantum Programming in Quipper
Quipper is a recently developed programming language for expressing quantum
computations. This paper gives a brief tutorial introduction to the language,
through a demonstration of how to make use of some of its key features. We
illustrate many of Quipper's language features by developing a few well known
examples of Quantum computation, including quantum teleportation, the quantum
Fourier transform, and a quantum circuit for addition.Comment: 15 pages, RC201
Climate impacts of a large-scale biofuels expansion
A global biofuels program will potentially lead to intense pressures on land supply and cause widespread transformations in land use. These transformations can alter the Earth climate system by increasing greenhouse gas (GHG) emissions from land use changes and by changing the reflective and energy exchange characteristics of land ecosystems. Using an integrated assessment model that links an economic model with climate, terrestrial biogeochemistry, and biogeophysics models, we examined the biogeochemical and biogeophysical effects of possible land use changes from an expanded global second-generation bioenergy program on surface temperatures over the first half of the 21st century. Our integrated assessment model shows that land clearing, especially forest clearing, has two concurrent effects—increased GHG emissions, resulting in surface air warming; and large changes in the land's reflective and energy exchange characteristics, resulting in surface air warming in the tropics but cooling in temperate and polar regions. Overall, these biogeochemical and biogeophysical effects will only have a small impact on global mean surface temperature. However, the model projects regional patterns of enhanced surface air warming in the Amazon Basin and the eastern part of the Congo Basin. Therefore, global land use strategies that protect tropical forests could dramatically reduce air warming projected in these regions.United States. Dept. of Energ
An efficient quantum algorithm for the hidden subgroup problem in extraspecial groups
Extraspecial groups form a remarkable subclass of p-groups. They are also
present in quantum information theory, in particular in quantum error
correction. We give here a polynomial time quantum algorithm for finding hidden
subgroups in extraspecial groups. Our approach is quite different from the
recent algorithms presented in [17] and [2] for the Heisenberg group, the
extraspecial p-group of size p3 and exponent p. Exploiting certain nice
automorphisms of the extraspecial groups we define specific group actions which
are used to reduce the problem to hidden subgroup instances in abelian groups
that can be dealt with directly.Comment: 10 page
ARIS-Campaign: intercomparison of three ground based 22 GHz radiometers for middle atmospheric water vapor at the Zugspitze in winter 2009
This paper presents the Alpine Radiometer Intercomparison at the Schneefernerhaus (ARIS), which took place in winter 2009 at the high altitude station at the Zugspitze, Germany (47.42° N, 10.98° E, 2650 m). This campaign was the first direct intercomparison between three new ground based 22 GHz water vapor radiometers for middle atmospheric profiling with the following instruments participating: MIRA 5 (Karlsruhe Institute of Technology), cWASPAM3 (Max Planck Institute for Solar System Research, Katlenburg-Lindau) and MIAWARA-C (Institute of Applied Physics, University of Bern). Even though the three radiometers all measure middle atmospheric water vapor using the same rotational transition line and similar fundamental set-ups, there are major differences between the front ends, the back ends, the calibration concepts and the profile retrieval. The spectrum comparison shows that all three radiometers measure spectra without severe baseline artifacts and that the measurements are in good general agreement. The measurement noise shows good agreement to the values theoretically expected from the radiometer noise formula. At the same time the comparison of the noise levels shows that there is room for instrumental and calibration improvement, emphasizing the importance of low elevation angles for the observation, a low receiver noise temperature and an efficient calibration scheme. <br><br> The comparisons of the retrieved profiles show that the agreement between the profiles of MIAWARA-C and cWASPAM3 with the ones of MLS is better than 0.3 ppmv (6%) at all altitudes. MIRA 5 has a dry bias of approximately 0.5 ppm (8%) below 0.1 hPa with respect to all other instruments. The profiles of cWASPAM3 and MIAWARA-C could not be directly compared because the vertical region of overlap was too small. The comparison of the time series at different altitude levels show a similar evolution of the H<sub>2</sub>O volume mixing ratio (VMR) for the ground based instruments as well as the space borne sensor MLS
Association between Diagnosed Anxiety and Depression and Exposure to Life Stressors during the COVID-19 Pandemic
Research suggests that mental health disorders heighten the risk of exposure to life stressors. Drawing on a sample of 754 adults from a survey distributed at six primary care clinics, we examine whether adults who reported ever being diagnosed with depression or anxiety were more likely to experience an employment disruption, a housing disruption, and/or report more COVID-19-related stressors during the COVID-19 pandemic. Individuals who reported ever being diagnosed with depression reported a greater burden (B=.75) of COVID-19-related stressors. Those who reported ever being diagnosed with anxiety had higher odds of experiencing an employment disruption (OR=1.90) and a housing disruption (OR=2.92) and reported about one (B=.97) additional COVID-19-related stressor. Our results suggest that the COVID-19 pandemic may have deepened existing mental health disparities by exposing those with a depression or anxiety diagnosis to additional life stressors
Random Oracles in a Quantum World
The interest in post-quantum cryptography - classical systems that remain
secure in the presence of a quantum adversary - has generated elegant proposals
for new cryptosystems. Some of these systems are set in the random oracle model
and are proven secure relative to adversaries that have classical access to the
random oracle. We argue that to prove post-quantum security one needs to prove
security in the quantum-accessible random oracle model where the adversary can
query the random oracle with quantum states.
We begin by separating the classical and quantum-accessible random oracle
models by presenting a scheme that is secure when the adversary is given
classical access to the random oracle, but is insecure when the adversary can
make quantum oracle queries. We then set out to develop generic conditions
under which a classical random oracle proof implies security in the
quantum-accessible random oracle model. We introduce the concept of a
history-free reduction which is a category of classical random oracle
reductions that basically determine oracle answers independently of the history
of previous queries, and we prove that such reductions imply security in the
quantum model. We then show that certain post-quantum proposals, including ones
based on lattices, can be proven secure using history-free reductions and are
therefore post-quantum secure. We conclude with a rich set of open problems in
this area.Comment: 38 pages, v2: many substantial changes and extensions, merged with a
related paper by Boneh and Zhandr
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