1,058 research outputs found
Axions and their Relatives
A review of the status of axions and axion-like particles is given. Special
attention is devoted to the recent results of the PVLAS collaboration, which
are in conflict with the CAST data and with the astrophysical constraints.
Solutions to the puzzle and the implications for new physics are discussed. The
question of axion-like particles being dark matter is also addressed.Comment: Updated version of an invited talk at the Axion Training (CERN,
December 2005). To appear as a Lecture Notes in Physics (Springer-Verlag),
edited by B. Beltran, M. Kuster and G. Raffel
Hard Instances of the Constrained Discrete Logarithm Problem
The discrete logarithm problem (DLP) generalizes to the constrained DLP,
where the secret exponent belongs to a set known to the attacker. The
complexity of generic algorithms for solving the constrained DLP depends on the
choice of the set. Motivated by cryptographic applications, we study sets with
succinct representation for which the constrained DLP is hard. We draw on
earlier results due to Erd\"os et al. and Schnorr, develop geometric tools such
as generalized Menelaus' theorem for proving lower bounds on the complexity of
the constrained DLP, and construct sets with succinct representation with
provable non-trivial lower bounds
Reproductive and Appetite Hormones and Bulimic Symptoms during Midlife
Eating disorders and related symptoms occur during midlife; however, little is known about their aetiology. It has been hypothesised that perimenopause represents a window of vulnerability for the development or exacerbation of eating disorder symptomatology because, like puberty, perimenopause is a period of reproductive hormone change. We compared symptoms of bulimia nervosa (bulimic symptomatology) assessed via mean scores on a self-report questionnaire in premenopausal and perimenopausal women. We also examined the association between hormone concentrations (reproductive/appetite) and bulimic symptomatology. No mean differences in bulimic symptomatology were observed between premenopause and perimenopause. However, there was a significant positive association between leptin and binge eating. Although no significant associations between reproductive hormones and bulimic symptomatology were observed, additional research is needed to provide definitive information. It is essential to learn more about the aetiology of eating disorders and related symptomatology across the lifespan in order to develop age-relevant treatment and prevention programs
Consensus statement on future directions for the behavioral and social sciences in oral health
The behavioral and social sciences are central to understanding and addressing oral and craniofacial health, diseases, and conditions. With both basic and applied approaches, behavioral and social sciences are relevant to every discipline in dentistry and all dental, oral, and craniofacial sciences, as well as oral health promotion programs and health care delivery. Key to understanding multilevel, interacting influences on oral health behavior and outcomes, the behavioral and social sciences focus on individuals, families, groups, cultures, systems, societies, regions, and nations. Uniquely positioned to highlight the importance of racial, cultural, and other equity in oral health, the behavioral and social sciences necessitate a focus on both individuals and groups, societal reactions to them related to power, and environmental and other contextual factors. Presented here is a consensus statement that was produced through an iterative feedback process. The statement reflects the current state of knowledge in the behavioral and social oral health sciences and identifies future directions for the field, focusing on 4 key areas: behavioral and social theories and mechanisms related to oral health, use of multiple and novel methodologies in social and behavioral research and practice related to oral health, development and testing of behavioral and social interventions to promote oral health, and dissemination and implementation research for oral health. This statement was endorsed by over 400 individuals and groups from around the world and representing numerous disciplines in oral health and the behavioral and social sciences. Having reached consensus, action is needed to advance and further integrate and translate behavioral and social sciences into oral health research, oral health promotion and health care, and the training of those working to ensure oral health for all
Production of Lambda and Sigma^0 hyperons in proton-proton collisions
This paper reports results on simultaneous measurements of the reaction
channels pp -> pK+\Lambda and pp -> pK+\Sigma^0 at excess energies of 204, 239,
and 284 MeV (\Lambda) and 127, 162, and 207 MeV (\Sigma^0). Total and
differential cross sections are given for both reactions. It is concluded from
the measured total cross sections that the high energy limit of the cross
section ratio is almost reached at an excess energy of only about 200 MeV. From
the differential distributions observed in the overall CMS as well as in the
Jackson and helicity frames, a significant contribution of interfering nucleon
resonances to the \Lambda production mechanism is concluded while resonant
\Sigma^0-production seems to be of lesser importance and takes place only
through specific partial waves of the entrance channel. The data also indicate
that kaon exchange plays a minor role in the case of \Lambda- but an important
role for \Sigma^0-production. Thus the peculiar energy dependence of the
\Lambda-to-\Sigma^0 cross section ratio appears in a new light as its
explanation requires more than mere differences between the p\Lambda and the
p\Sigma^0 final state interaction. The data provide a benchmark for theoretical
models already available or yet to come.Comment: 18 pages, 10 figures; accepted by The European Physical Journal A
(EPJ A
Signatures of the slow solar wind streams from active regions in the inner corona
Some of local sources of the slow solar wind can be associated with
spectroscopically detected plasma outflows at edges of active regions
accompanied with specific signatures in the inner corona. The EUV telescopes
(e.g. SPIRIT/CORONAS-F, TESIS/CORONAS-Photon and SWAP/PROBA2) sometimes
observed extended ray-like structures seen at the limb above active regions in
1MK iron emission lines and described as "coronal rays". To verify the
relationship between coronal rays and plasma outflows, we analyze an isolated
active region (AR) adjacent to small coronal hole (CH) observed by different
EUV instruments in the end of July - beginning of August 2009. On August 1 EIS
revealed in the AR two compact outflows with the Doppler velocities V =10-30
km/s accompanied with fan loops diverging from their regions. At the limb the
ARCH interface region produced coronal rays observed by EUVI/STEREO-A on July
31 as well as by TESIS on August 7. The rays were co-aligned with open magnetic
field lines expanded to the streamer stalks. Using the DEM analysis, it was
found that the fan loops diverged from the outflow regions had the dominant
temperature of ~1 MK, which is similar to that of the outgoing plasma streams.
Parameters of the solar wind measured by STEREO-B, ACE, WIND, STEREO-A were
conformed with identification of the ARCH as a source region at the
Wang-Sheeley-Arge map of derived coronal holes for CR 2086. The results of the
study support the suggestion that coronal rays can represent signatures of
outflows from ARs propagating in the inner corona along open field lines into
the heliosphere.Comment: Accepted for publication in Solar Physics; 31 Pages; 13 Figure
4pi Models of CMEs and ICMEs
Coronal mass ejections (CMEs), which dynamically connect the solar surface to
the far reaches of interplanetary space, represent a major anifestation of
solar activity. They are not only of principal interest but also play a pivotal
role in the context of space weather predictions. The steady improvement of
both numerical methods and computational resources during recent years has
allowed for the creation of increasingly realistic models of interplanetary
CMEs (ICMEs), which can now be compared to high-quality observational data from
various space-bound missions. This review discusses existing models of CMEs,
characterizing them by scientific aim and scope, CME initiation method, and
physical effects included, thereby stressing the importance of fully 3-D
('4pi') spatial coverage.Comment: 14 pages plus references. Comments welcome. Accepted for publication
in Solar Physics (SUN-360 topical issue
Field-induced single-ion magnetic behaviour in a highly luminescent Er3+ complex
This work is licensed under a Creative Commons Attribution Non-Commercial No Derivatives License
A free and open source programming library for landscape metrics calculations
Landscape metrics are used in a wide range of environmental studies such as land use change and land degradation studies, soil erosion and run-off predictions, management of hunting communities, and strategic planning for environmental management, to name just a few. Due to their utility for a variety of applications, there are many indices and software packages that have been designed to provide calculations and analysis of landscape structure patterns in categorical maps. With the purpose of making a comparison between the most used tools (Fragstats, V-Late, PA4...), this paper examines their advantages and disadvantages in order to create a list of common features that need to be incorporated into this type of software. An Application Programming Interface (API) is produced without limitations on data input, that is capable of calculating vector or raster metrics and is extensible. This API should make it possible not only to build third party applications easily, but also make it possible to add new metrics and research into new paradigms related to traditional landscape metrics. Land-metrics DIY (DoIt Yourself) is the library presented in this paper. It can calculate almost 40 landscape metrics from geometry provided by an ESRI Shapefile. © 2011 Elsevier Ltd.We especially appreciate the comments and suggestions by A. Jakeman and three anonymous reviewers which led to substantial improvements of the manuscript. This paper is partially supported by the FPU - Doctoral Research Scholarship program of the "Ministerio de Educacion de Espana" (2007-2011). Moreover, we would like to thank all the FOSS community, and in particular to Diego Guidi (NTS main developer) for their interesting and important work. Of course, we also thank the OGC and all FOSS projects related to spatial information because they suppose a strategic support to the further development of our idea and other possible GIS projects.Zaragozi Zaragozi, BM.; Belda Antoli, A.; Linares Pellicer, JJ.; Martínez-Pérez, JE.; Navarro, JT.; Esparza Peidro, J. (2012). A free and open source programming library for landscape metrics calculations. Environmental Modelling and Software. 31:131-140. doi:10.1016/j.envsoft.2011.10.009S1311403
Thermodynamic Measurements in a Strongly Interacting Fermi Gas
We conduct a series of measurements on the thermodynamic properties of an
optically-trapped strongly interacting Fermi gas, including the energy ,
entropy , and sound velocity . Our model-independent measurements of
and enable a precision study of the finite temperature thermodynamics. The
data are directly compared to several recent predictions. The
temperature in both the superfluid and normal fluid regime is obtained from the
fundamental thermodynamic relation by parameterizing
the data. Our data are also used to experimentally calibrate the
endpoint temperatures obtained for adiabatic sweeps of the magnetic field
between the ideal and strongly interacting regimes. This enables the first
experimental calibration of the temperature scale used in experiments on
fermionic pair condensation. Our calibration shows that the ideal gas
temperature measured for the onset of pair condensation corresponds closely to
the critical temperature estimated in the strongly interacting regime from the
fits to our data. The results are in very good agreement with recent
predictions. Finally, using universal thermodynamic relations, we estimate the
chemical potential and heat capacity of the trapped gas from the data.Comment: 29 pages, 12 figures. To appear in JLTP online, and in the January,
2009 volum
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