First-order transitions and triple point on a random p-spin interaction model

The effects of competing quadrupolar- and spin-glass orderings are investigated on a spin-1 Ising model with infinite-range random $p$-spin interactions. The model is studied through the replica approach and a phase diagram is obtained in the limit $p\to\infty$. The phase diagram, obtained within replica-symmetry breaking, exhibits a very unusual feature in magnetic models: three first-order transition lines meeting at a commom triple point, where all phases of the model coexist.Comment: 9 pages, 2 ps figures include

Critical boron-doping levels for generation of dislocations in synthetic diamond

Defects induced by boron doping in diamond layers were studied by transmission electron microscopy. The existence of a critical boron doping level above which defects are generated is reported. This level is found to be dependent on the CH4 /H2 molar ratios and on growth directions. The critical boron concentration lied in the 6.5–17.0 X 10 20 at/cm3 range in the direction and at 3.2 X 1021 at/cm 3 for the one. Strain related effects induced by the doping are shown not to be responsible. From the location of dislocations and their Burger vectors, a model is proposed, together with their generation mechanism.6 page

Micro-simulation of the impact of different speeds on safety road travel and urban travel time: case study in the city of Guimarães

In recent days, the use of micro-simulation as an additional tool for the study of the network makes this management faster and more efficient, avoiding in situ studies. However, although it is a useful tool, it is necessary that the model under study is the best represented possible in order to obtain results that best fit the reality of the road, and a poor calibration of the model can provide results that do not fit the good management of the road under study. In this sense, using micro-simulation, more precisely to the VISSIM PTV software, a road network at the microscopic level will be evaluated as well as the parameters that most influence the route of the users within that network. The parameters will be modified according to the modeler so as to obtain a model as close to reality as possible. The most appropriate criteria for the calibration and validation of the model will also be chosen. The road safety of the network will also be analyzed using the SSAM software. Here the network's points of conflict will be analyzed, characterizing them as to the type and its severity. Subsequently, a sensitivity analysis will be introduced, where some parameters will be modified individually or together, in order to assess their influence on the network, thus assessing the importance of each in the vehicles.(undefined

Temperature oscillations of magnetization observed in nanofluid ferromagnetic graphite

We report on unusual magnetic properties observed in the nanofluid room-temperature ferromagnetic graphite (with an average particle size of l=10nm). More precisely, the measured magnetization exhibits a low-temperature anomaly (attributed to manifestation of finite size effects below the quantum temperature) as well as pronounced temperature oscillations above T=50K (attributed to manifestation of the hard-sphere type pair correlations between ferromagnetic particles in the nanofluid)

Avaliação do valor de cultivo e uso de cultivares e linhagens de algodão herbáceo no Ceará - 2003.

Linhagens de algodãobitstream/CNPA/19624/1/COMTEC203.PD