263 research outputs found
Field-Induced Magnetization Steps in Intermetallic Compounds and Manganese Oxides: The Martensitic Scenario
Field-induced magnetization jumps with similar characteristics are observed
at low temperature for the intermetallic germanide Gd5Ge4and the mixed-valent
manganite Pr0.6Ca0.4Mn0.96Ga0.04O3. We report that the field location -and even
the existence- of these jumps depends critically on the magnetic field sweep
rate used to record the data. It is proposed that, for both compounds, the
martensitic character of their antiferromagnetic-to-ferromagnetic transitions
is at the origin of the magnetization steps.Comment: 4 pages,4 figure
A Gaussian distribution for refined DT invariants and 3D partitions
We show that the refined Donaldson-Thomas invariants of C3, suitably
normalized, have a Gaussian distribution as limit law. Combinatorially these
numbers are given by weighted counts of 3D partitions. Our technique is to use
the Hardy-Littlewood circle method to analyze the bivariate asymptotics of a
q-deformation of MacMahon's function. The proof is based on that of E.M. Wright
who explored the single variable case.Comment: 11 pages and 3 figure
A Characterization of Bispecial Sturmian Words
A finite Sturmian word w over the alphabet {a,b} is left special (resp. right
special) if aw and bw (resp. wa and wb) are both Sturmian words. A bispecial
Sturmian word is a Sturmian word that is both left and right special. We show
as a main result that bispecial Sturmian words are exactly the maximal internal
factors of Christoffel words, that are words coding the digital approximations
of segments in the Euclidean plane. This result is an extension of the known
relation between central words and primitive Christoffel words. Our
characterization allows us to give an enumerative formula for bispecial
Sturmian words. We also investigate the minimal forbidden words for the set of
Sturmian words.Comment: Accepted to MFCS 201
Integration of Tmc1/2 into the mechanotransduction complex in zebrafish hair cells is regulated by Transmembrane O-methyltransferase (Tomt).
Transmembrane O-methyltransferase (TOMT / LRTOMT) is responsible for non-syndromic deafness DFNB63. However, the specific defects that lead to hearing loss have not been described. Using a zebrafish model of DFNB63, we show that the auditory and vestibular phenotypes are due to a lack of mechanotransduction (MET) in Tomt-deficient hair cells. GFP-tagged Tomt is enriched in the Golgi of hair cells, suggesting that Tomt might regulate the trafficking of other MET components to the hair bundle. We found that Tmc1/2 proteins are specifically excluded from the hair bundle in tomt mutants, whereas other MET complex proteins can still localize to the bundle. Furthermore, mouse TOMT and TMC1 can directly interact in HEK 293 cells, and this interaction is modulated by His183 in TOMT. Thus, we propose a model of MET complex assembly where Tomt and the Tmcs interact within the secretory pathway to traffic Tmc proteins to the hair bundle
Structural resolvent estimates and derivative nonlinear Schrodinger equations
A refinement of uniform resolvent estimate is given and several smoothing
estimates for Schrodinger equations in the critical case are induced from it.
The relation between this resolvent estimate and radiation condition is
discussed. As an application of critical smoothing estimates, we show a global
existence results for derivative nonlinear Schrodinger equations.Comment: 21 page
Azokh caves excavations 2002-2006: Middle-Upper palaeolithic transition in Nagorno-Karabagh
Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEpu
AUTOMAÇÃO DOS OPERADORES DE AGREGAÇÃO E DESLOCAMENTO PARA GENERALIZAÇÃO CARTOGRÁFICA NA REPRESENTAÇÃO DE REDES SOCIAIS
A generalização cartográfica sempre teve um caráter subjetivo, o que implica que mapas de mesma escala derivados de um mesmo mapa fonte, por diferentes cartógrafos, resultem em diferentes representações. Além disso, com a evolução da informática surgiu a necessidade da padronização deste processo para que os produtos cartográficos gerados fossem sempre os mesmos. Nesta pesquisa aborda-se a aplicação da generalização na representação de redes sociais de assistência social. Os nós desta rede são os atores sociais - indivíduos, grupos ou instituições - que atuam em uma região e as ligações existentes entre os mesmos são os arcos, sendo que estas ligações não são físicas. O foco do estudo é a automação dos operadores geométricos de agregação e deslocamento agindo sobre as feições pontuais, que são os atores sociais. Quando há sobreposição entre os atores sociais, os que possuem mesma classificação são agregados gerando um novo símbolo. Já o deslocamento é utilizado para resolver a sobreposição entre atores sociais de classes diferentes. Para tanto, foi desenvolvido um programa para a execução da generalização cujos resultados são apresentados neste artigo
Organic Superconductors: when correlations and magnetism walk in
This survey provides a brief account for the start of organic
superconductivity motivated by the quest for high Tc superconductors and its
development since the eighties'. Besides superconductivity found in 1D organics
in 1980, progresses in this field of research have contributed to better
understand the physics of low dimensional conductors highlighted by the wealth
of new remarkable properties. Correlations conspire to govern the low
temperature properties of the metallic phase. The contribution of
antiferromagnetic fluctuations to the interchain Cooper pairing proposed by the
theory is borne out by experimental investigations and supports
supercondutivity emerging from a non Fermi liquid background. Quasi one
dimensional organic superconductors can therefore be considered as simple
prototype systems for the more complex high Tc materials.Comment: 41 pages, 21 figures to be published in Journal of Superconductivity
and Novel Magnetis
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