565 research outputs found
Cold atoms at unitarity and inverse square interaction
Consider two identical atoms in a spherical harmonic oscillator interacting
with a zero-range interaction which is tuned to produce an s-wave zero-energy
bound state. The quantum spectrum of the system is known to be exactly
solvable. We note that the same partial wave quantum spectrum is obtained by
the one-dimensional scale-invariant inverse square potential. Long known as the
Calogero-Sutherland-Moser (CSM) model, it leads to Fractional Exclusion
Statistics (FES) of Haldane and Wu. The statistical parameter is deduced from
the analytically calculated second virial coefficient. When FES is applied to a
Fermi gas at unitarity, it gives good agreement with experimental data without
the use of any free parameter.Comment: 11 pages, 3 figures, To appear in J. Phys. B. Atomic, Molecular and
Optical Physic
Pulse-driven quantum dynamics beyond the impulsive regime
We review various unitary time-dependent perturbation theories and compare
them formally and numerically. We show that the Kolmogorov-Arnold-Moser
technique performs better owing to both the superexponential character of
correction terms and the possibility to optimize the accuracy of a given level
of approximation which is explored in details here. As an illustration, we
consider a two-level system driven by short pulses beyond the sudden limit.Comment: 15 pages, 5 color figure
Tribological properties of room temperature fluorinated graphite heat-treated under fluorine atmosphere
This work is concerned with the study of the tribologic properties of room temperature fluorinated graphite heat-treated under fluorine atmosphere. The fluorinated compounds all present good intrinsic friction properties (friction coefficient in the range 0.05â0.09). The tribologic performances are optimized if the materials present remaining graphitic domains (influenced by the presence of intercalated fluorinated species) whereas the perfluorinated compounds, where the fluorocarbon layers are corrugated (armchair configuration of the saturated carbon rings) present higher friction coefficients. Raman analyses reveal that the friction process induces severe changes in the materials structure especially the partial re-building of graphitic domains in the case of perfluorinated compounds which explains the improvement of ÎŒ during the friction tests for these last materials
Divergences in Real-Time Classical Field Theories at Non-Zero Temperature
The classical approximation provides a non-perturbative approach to
time-dependent problems in finite temperature field theory. We study the
divergences in hot classical field theory perturbatively. At one-loop, we show
that the linear divergences are completely determined by the classical
equivalent of the hard thermal loops in hot quantum field theories, and that
logarithmic divergences are absent. To deal with higher-loop diagrams, we
present a general argument that the superficial degree of divergence of
classical vertex functions decreases by one with each additional loop: one-loop
contributions are superficially linearly divergent, two-loop contributions are
superficially logarithmically divergent, and three- and higher-loop
contributions are superficially finite. We verify this for two-loop SU(N)
self-energy diagrams in Feynman and Coulomb gauges. We argue that hot,
classical scalar field theory may be completely renormalized by local (mass)
counterterms, and discuss renormalization of SU(N) gauge theories.Comment: 31 pages with 7 eps figure
Measurement and comparison of individual external doses of high-school students living in Japan, France, Poland and Belarus -- the "D-shuttle" project --
Twelve high schools in Japan (of which six are in Fukushima Prefecture), four
in France, eight in Poland and two in Belarus cooperated in the measurement and
comparison of individual external doses in 2014. In total 216 high-school
students and teachers participated in the study. Each participant wore an
electronic personal dosimeter "D-shuttle" for two weeks, and kept a journal of
his/her whereabouts and activities. The distributions of annual external doses
estimated for each region overlap with each other, demonstrating that the
personal external individual doses in locations where residence is currently
allowed in Fukushima Prefecture and in Belarus are well within the range of
estimated annual doses due to the background radiation level of other
regions/countries
Incorporation of calcium in glasses: a key to understand the vitrification of sewage sludge
The quantity of sewage sludge generated daily by wastewater treatment plants represents a major environmental problem and a financial burden for plant operators. Valorization strategies focusing on reusing sewage sludge as a raw material are currently developed. Vitrification can help us reduce the volume of waste and binds the components in the structure of chemically stable glasses and glassâceramics. In this study, the vitrification of sewage sludge inside a basaltic rock has been simulated by producing glasses and a glassâceramic from basalt enriched in calcium that lie between the stability fields of pyroxene and melilite in the system CaOâMgOâSiO2âAl2O3. CaO addition causes the oxidation of the melt at above the liquidus, increases the crystallization temperature, decreases the melting temperature and improves the microhardness of the glasses Glassâceramic processes improves the properties of the Caâdoped basalt glass. The microhardness of the glass (8.2 GPa) and the glassâceramic (8.6 GPa) and leaching tests (in the ppb range) place both the glass and the glassâceramics at the high end of the mechanical properties and chemical resistance of ceramic tiles for the building industry
International multicentre observational study to assess the efficacy and safety of a 0·5 mg kgâ1 per day starting dose of oral corticosteroids to treat bullous pemphigoid
BackgroundEuropean guidelines propose a 0 center dot 5 mg kg(-1) per day dose of oral prednisone as initial treatment for bullous pemphigoid (BP). We assessed the safety and efficacy of this regimen depending on BP extent and general condition of the patients.MethodsIn a prospective international study, we consecutively included all patients diagnosed with BP. Patients received a 0 center dot 5 mg kg(-1) per day dose of prednisone, which was then gradually tapered 15 days after disease control, with the aim of stopping prednisone or maintaining minimal treatment (0 center dot 1 mg kg(-1) per day) within 6 months after the start of treatment. The two coprimary endpoints were control of disease activity at day 21 and 1-year overall survival. Disease severity was assessed according to the Bullous Pemphigoid Disease Area Index (BPDAI) score.ResultsIn total, 198 patients were included between 2015 and 2017. The final analysis comprised 190 patients with a mean age of 80 center dot 9 (SD 9 center dot 1) years. Control of disease activity was achieved at day 21 in 119 patients [62 center dot 6%, 95% confidence interval (CI) 55 center dot 3-69.5]; 18 of 24 patients (75%, 95% CI 53 center dot 3-90 center dot 2), 75 of 110 patients (68 center dot 8%, 95% CI 59 center dot 2-77 center dot 3) and 26 of 56 patients (46.4%, 95% CI 33 center dot 0-60 center dot 3) had mild, moderate and severe BP, respectively (P = 0 center dot 0218). A total of 30 patients died during the study. The overall Kaplan-Meier 1-year survival was 82 center dot 6% (95% CI 76 center dot 3-87 center dot 4) corresponding to 90 center dot 9%, 83 center dot 0% and 80 center dot 0% rates in patients with mild, moderate and severe BP, respectively (P = 0 center dot 5). Thresholds of 49 points for BPDAI score and 70 points for Karnofsky score yielded maximal Youden index values with respect to disease control at day 21 and 1-year survival, respectively.ConclusionsA 0 center dot 5 mg kg(-1) per day dose of prednisone is a valuable therapeutic option in patients with mild or moderate BP whose general condition allows them to be autonomous.</p
On the Origin and Spread of the Scab Disease of Apple: Out of Central Asia
Background Venturia inaequalis is an ascomycete fungus responsible for apple scab, a disease that has invaded almost all apple growing regions worldwide, with the corresponding adverse effects on apple production. Monitoring and predicting the effectiveness of intervention strategies require knowledge of the origin, introduction pathways, and population biology of pathogen populations. Analysis of the variation of genetic markers using the inferential framework of population genetics offers the potential to retrieve this information. Methodology/Principal Findings Here, we present a population genetic analysis of microsatellite variation in 1,273 strains of V. inaequalis representing 28 orchard samples from seven regions in five continents. Analysis of molecular variance revealed that most of the variation (88%) was distributed within localities, which is consistent with extensive historical migrations of the fungus among and within regions. Despite this shallow population structure, clustering analyses partitioned the data set into separate groups corresponding roughly to geography, indicating that each region hosts a distinct population of the fungus. Comparison of the levels of variability among populations, along with coalescent analyses of migration models and estimates of genetic distances, was consistent with a scenario in which the fungus emerged in Central Asia, where apple was domesticated, before its introduction into Europe and, more recently, into other continents with the expansion of apple growing. Across the novel range, levels of variability pointed to multiple introductions and all populations displayed signatures of significant post-introduction increases in population size. Most populations exhibited high genotypic diversity and random association of alleles across loci, indicating recombination both in native and introduced areas. Conclusions/Significance Venturia inaequalis is a model of invasive phytopathogenic fungus that has now reached the ultimate stage of the invasion process with a broad geographic distribution and well-established populations displaying high genetic variability, regular sexual reproduction, and demographic expansion.Contexte Venturia inaequalis est un champignon ascomycete responsable de la tavelure du pommier, une maladie qui a envahi presque toutes les rĂ©gions du monde oĂč le pommier est cultivĂ© posant ainsi de graves problĂšmes en production. PrĂ©venir et enrayer efficacement la rĂ©ussite dâun tel succĂšs invasif nĂ©cessite des connaissances approfondies sur lâorigine, les voies dâintroduction, la biologie et la gĂ©nĂ©tique de ces populations invasives. En utilisant le potentiel dâinfĂ©rence de la gĂ©nĂ©tique des populations, lâanalyse de la variation de marqueurs gĂ©nĂ©tiques offre la possibilitĂ© dâaccĂ©der Ă ces informations. MĂ©thodologie et Principaux rĂ©sultats Ici nous prĂ©sentons lâanalyse de donnĂ©es microsatellites obtenues pour 1273 souches de V. inaequalis provenant de 28 vergers prĂ©levĂ©es dans 7 rĂ©gions sur les 5 continents. Lâanalyse de la variance molĂ©culaire rĂ©vĂšle que 88% de la variation se retrouve dans les vergers Ă©chantillonnĂ©s, ce qui est compatible avec dâimportantes migrations historiques du champignon entre et Ă lâintĂ©rieur mĂȘme des rĂ©gions. MalgrĂ© cette trĂšs faible structuration des populations, les diffĂ©rentes analyses de clustering mettent en Ă©vidence un partage des populations en groupes sĂ©parĂ©s correspondant Ă leur origine gĂ©ographique, montrant ainsi que chaque rĂ©gion hĂ©berge une population distincte du champignon. Ensemble, les rĂ©sultats obtenus sur la comparaison du niveau de variabilitĂ© entre populations, les analyses de coalescence et les modĂšles de migration testĂ©s plaident en faveur dâun scĂ©nario dans lequel le champignon aurait Ă©mergĂ© dâAsie Centrale, oĂč le pommier a Ă©tĂ© domestiquĂ©, avant dâĂȘtre introduit en Europe puis plus rĂ©cemment dans les autres continents suite Ă lâexpansion de la culture du pommier. Les niveaux de variabilitĂ© indiquent que ces territoires ont subi des introductions multiples et que les populations portent toutes des signatures rĂ©vĂ©lant de fortes expansions dĂ©mographiques aprĂšs leur introduction. Enfin, la forte diversitĂ© gĂ©notypique des populations et lâassociation alĂ©atoire des allĂšles entre loci suggĂšrent que le champignon prĂ©sente une reproduction sexuĂ©e rĂ©guliĂšre Ă la fois dans les rĂ©gions oĂč il a Ă©tĂ© introduit et dans sa rĂ©gion native. Conclusion et PortĂ©e. Venturia inaequalis est un modĂšle de champignons phytopathogĂšne invasif qui a maintenant atteint le stade ultime du processus invasif, câest Ă dire une trĂšs large distribution gĂ©ographique par des populations bien Ă©tablies montrant une grande diversitĂ© gĂ©nĂ©tique, une reproduction sexuĂ©e rĂ©guliĂšre et une histoire dâexpansion dĂ©mographique
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