783 research outputs found
O crescimento de uma cidade francesa: Tolosa
(Primeiras linhas do texto)"O desenvolvimento das cidades francesas apresenta evidentemente ao geógrafo um quadro muito diferente da imagem que lhe oferecem as cidades do Novo Mundo. Elas são, na maioria das vêzes, muito antigas; muitas delas poderiam, como recentemente Paris, festejar seus bi-milenários. (...)
En France: une série d'histoires provinciales
 Nous avons gardé, ma Femme et moi, un souvenir trop vif ettrop ému des trois mois que nous avons passés à São Paulo d'août à novembre 1952, — une véritable saudade, — de l'accueil si généreuxet si délicat qui nous fut alors prodigué, de l'attention que reçut dela part des étudiants l'enseignement que je donnai dans la chaire demon Ami le professeur EurÃpedes Simões de Paula, pour que je neconsidère pas à la fois comme un devoir et un plaisir de participer à ce centième numéro de la Revista de História
Percolation and Magnetization in the Continuous Spin Ising Model
In the strong coupling limit the partition function of SU(2) gauge theory can
be reduced to that of the continuous spin Ising model with nearest neighbour
pair-interactions. The random cluster representation of the continuous spin
Ising model in two dimensions is derived through a Fortuin-Kasteleyn
transformation, and the properties of the corresponding cluster distribution
are analyzed. It is shown that for this model, the magnetic transition is
equivalent to the percolation transition of Fortuin-Kasteleyn clusters, using
local bond weights. These results are also illustrated by means of numerical
simulations
Cinquante ans de pratiques culturelles en France
Menée tout au long de l’année 2018 auprès d’un échantillon de plus de 9 200 personnes en France métropolitaine, l’enquête sur les pratiques culturelles est la sixième édition d’une série commencée au début des années 1970 et destinée à mesurer la participation de la population aux loisirs et à la vie culturelle. Cette sixième édition permet d’observer l’évolution des pratiques culturelles depuis la précédente édition réalisée en 2008 mais aussi depuis la décennie 1970, et offre ainsi un panorama de près d’un demi-siècle des dynamiques des pratiques culturelles de la population âgée de 15 ans et plus. Pour chaque activité, le taux de pénétration est analysé par générations afin de saisir les évolutions de long terme et les effets d’époque, puis étudié selon les caractéristiques sociodémographiques des individus
Predictive maintenance of an unreliable two-unit system
We consider a system composed of two independent and non-identical units. This system is under periodic inspection. Each unit is characterized by a variable whose value evolves from one inspection to the next one according to an exponential distribution. The parameters of this distribution can be different for the two units. The system breaks down if a least one of the two states exceeds a given value. These limits are referred to as breakdown limits. A preventive maintenance is applied on one unit if its state is less than the breakdown limit but exceeds a given threshold, called maintenance limit. The cost of a maintenance is much less than the cost of a repair. If a repair or a maintenance is applied on one unit, while the state of the second unit is less than the maintenance limit, a maintenance is performed on this second unit. The goal of this study is to adjust the maintenance limits to minimize the long-run average cost per unit of time. We study the probability density for the system to be in a given state. We then give the analytical expression of the cost function according to the maintenance limits. The values of these limits that minimize this function are then calculated using gradient estimation
Euler-Poincare' Characteristic and Phase Transition in the Potts Model
Recent results concerning the topological properties of random geometrical
sets have been successfully applied to the study of the morphology of clusters
in percolation theory. This approach provides an alternative way of inspecting
the critical behaviour of random systems in statistical mechanics. For the 2d
q-states Potts model with q <= 6, intensive and accurate numerics indicates
that the average of the Euler characteristic (taken with respect to the
Fortuin-Kasteleyn random cluster measure) is an order parameter of the phase
transition.Comment: 17 pages, 8 figures, 1 tabl
8-vinyl-deoxyadenosine, an alternative fluorescent nucleoside analog to 2′-deoxyribosyl-2-aminopurine with improved properties
We report here the synthesis and the spectroscopic characterization of 8-vinyl-deoxyadenosine (8vdA), a new fluorescent analog of deoxyadenosine. 8vdA was found to absorb and emit in the same wavelength range as 2′-deoxyribosyl-2-aminopurine (2AP), the most frequently used fluorescent nucleoside analog. Though the quantum yield of 8vdA is similar to that of 2AP, its molar absorption coefficient is about twice, enabling a more sensitive detection. Moreover, the fluorescence of 8vdA was found to be sensitive to temperature and solvent but not to pH (around neutrality) or coupling to phosphate groups. Though 8vdA is base sensitive and susceptible to depurination, the corresponding phosphoramidite was successfully prepared and incorporated in oligonucleotides of the type d(CGT TTT XNX TTT TGC) where N = 8vdA and X = A, T or C. The 8vdA-labeled oligonucleotides gave more stable duplexes than the corresponding 2AP-labeled sequences when X = A or T, indicating that 8vdA is less perturbing than 2AP and probably adopts an anti conformation to preserve the Watson–Crick H-bonding. In addition, the quantum yield of 8vdA is significantly higher than 2AP in all tested oligonucleotides in both their single strand and duplex states. The steady-state and time-resolved fluorescence parameters of 8vdA and 2AP were found to depend similarly on the nature of their flanking residues and on base pairing, suggesting that their photophysics are governed by similar mechanisms. Taken together, our data suggest that 8vdA is a non perturbing nucleoside analog that may be used with improved sensitivity for the same applications as 2AP
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