Linear orderings of random geometric graphs (extended abstract)

In random geometric graphs, vertices are randomly distributed on [0,1]^2 and pairs of vertices are connected by edges whenever they are sufficiently close together. Layout problems seek a linear ordering of the vertices of a graph such that a certain measure is minimized. In this paper, we study several layout problems on random geometric graphs: Bandwidth, Minimum Linear Arrangement, Minimum Cut, Minimum Sum Cut, Vertex Separation and Bisection. We first prove that some of these problems remain \NP-complete even for geometric graphs. Afterwards, we compute lower bounds that hold with high probability on random geometric graphs. Finally, we characterize the probabilistic behavior of the lexicographic ordering for our layout problems on the class of random geometric graphs.Postprint (published version

Convergence theorems for some layout measures on random lattice and random geometric graphs

This work deals with convergence theorems and bounds on the cost of several layout measures for lattice graphs, random lattice graphs and sparse random geometric graphs. For full square lattices, we give optimal layouts for the problems still open. Our convergence theorems can be viewed as an analogue of the Beardwood, Halton and Hammersley theorem for the Euclidian TSP on random points in the $d$-dimensional cube. As the considered layout measures are non-subadditive, we use percolation theory to obtain our results on random lattices and random geometric graphs. In particular, we deal with the subcritical regimes on these class of graphs.Postprint (published version

Bound States of Heavy Flavor Hyperons

Several realistic phenomenological nucleon-nucleon interaction models are employed to investigate the possibility of bound deuteron-like states of such heavy flavor hyperons and nucleons, for which the interaction between the light flavor quark components is expected to be the most significant interaction. The results indicate that deuteron-like bound states are likely to form between nucleons and the $\Xi_c^{'}$ and $\Xi_{cc}$ charm hyperons as well as between $\Xi$ hyperons and double-charm hyperons. Bound states between two $\Sigma_c$ hyperons are also likely. In the case of beauty hyperons the corresponding states are likely to be deeply bound.Comment: 25 pages, 3 figures. Accepted Nucl. Phys.

Communication tree problems

In this paper, we consider random communication requirements and several cost measures for a particular model of tree routing on a complete network. First we show that a random tree does not give any approximation. Then give approximation algorithms for the case for two random models of requirements.Postprint (published version

Nuclei of Double-Charm Hyperons

The ground states of double-charm hyperons form a spin 1/2 isospin 1/2 multiplet analogous to that of nucleons. Their main strong interaction may be inferred directly from the corresponding nucleon-nucleon interaction by multiplication of the interaction components by the appropriate fractional difference between interaction strengths for pairs of light flavor quarks and pairs of triplets, e.g. nucleons, of light flavor quarks. By construction of the interaction between the recently discovered double-charm hyperons by this method from several realistic nucleon-nucleon interaction models it is shown that double-charm hyperons are likely to form bound (or possibly meta-stable) states akin to the deuteron in the spin triplet state. Double beauty baryons would form corresponding deeply bound states. Nucleons and double charm (beauty) hyperons will also form bound states. The existence of hypernuclei with double-charm and double-beauty hyperons, which are stable against the strong decay, is very likely.Comment: Revised version. Conclusions unchange

Tetraquarks in a chiral constituent quark model

We analyze the possibility of heavy-light tetraquark bound states by means of a chiral constituent quark model. The study is done in a variational approach. Special attention is paid to the contribution given by the different terms of the interacting potential and also to the role played by the different color channels. We find a stable state for both $qq\bar{c}\bar{c}$ and $qq\bar{b}\bar{b}$ configurations. Possible decay modes of these structures are analyzed.Comment: 13 pages, no figures. Accepted for publication in European Journal of Physics

Characterization of Carbon Molecular Sieve Membranes Supported on Ceramic Tubes

Carbon molecular sieve membranes have been analyzed in supported and unsupported configurations in this experimental study. The membranes were used to adsorb CO2, N2 and CH4, and their adsorption data were analyzed to establish differences in rate and capacity of adsorption between the two types of samples (supported and unsupported). Experimental results show an important effect of the support, which can be considered as an additional parameter to tailor pore size on these carbon membranes. Immersion calorimetry values were measured by immersing the membranes into liquids of different molecular dimensions (dichloromethane, benzene, n-hexane, 2,2-dimethylbutane). Similarities were found between adsorption and calorimetric analysis. The pore volume of the samples analyzed ranged from 0.016 to 0.263 cm3/g. The effect of the pyrolysis temperature, either 550 or 700 °C, under N2 atmosphere was also analyzed. Quantification of the pore-size distribution of the support was done by liquid-liquid displacement porosimetry. The composite membrane was used for CO2/CH4 separation before and after pore plugging was done. The ideal selectivity factors value (4.47) was over the Knudsen theoretical factor (0.60) for membrane pyrolyzed at 600 °C, which indicates the potential application of these membranes for the separation of low-molecular weight gases.The authors are indebted to the Spanish Government for financial support (Project CTQ2008-02491, partially funded by the FEDER program of the European Union) and to the commission of European Communities Specific OpenTok Project MTKD-LT-2005-030040

Análisis de la aplicación de la NIC 2 inventarios en la estación de servicio Grupo VCV Gas S.A.C., Ate, 2021

El presente estudio, tiene por objetivo central analizar la aplicación de la NIC 2 Inventarios en la estación de servicio, pues se ha observado la falta de veracidad de la información contable en cuanto a la valuación de sus inventarios. La investigación es de tipo básico de enfoque mixto, de diseño no experimental, transversal y de alcance descriptivo, la población está conformada por los cuadros de costos, kardex y estados financieros del 2017 hasta 2021, y la muestra es enero 2021. Como técnica de recolección de datos, se utilizó la entrevista y el análisis documental. Se obtuvo como resultado que no se contabilizaron como costos de adquisición todos los conceptos detallados en la norma, como son los fletes por el importe de S/32,286.00 y las mermas normales por importe de S/6,784.00; lo cual género que el costo de ventas calculado mediante el método promedio ponderado sea inexacto, asimismo el costo de distribución por el importe de S/7,200.00, no fue revelado en el estado de resultados, el mismo que tampoco se detalla en las notas. Finalmente, se concluyó que en la empresa no se aplica correctamente la norma, esto género que la información financiera reflejada en los estados financieros esté distorsionada

Building resilience to water scarcity in Southern Spain: A case study of rice farming in Doñana protected wetlands

Agricultural water management needs to evolve in view of increased water scarcity, especially when farming and natural protected areas are closely linked. In the study site of Don?ana (southern Spain), water is shared by rice producers and a world heritage biodiversity ecosystem. Our aim is to contribute to defining adaptation strategies that may build resilience to increasing water scarcity and minimize water conflicts among agricultural and natural systems. The analytical framework links a participatory process with quantitative methods to prioritize the adaptation options. Bottom-up proposed adaptation measures are evaluated by a multi-criteria analysis (MCA) that includes both socioeconomic criteria and criteria of the ecosystem services affected by the adaptation options. Criteria weights are estimated by three different methods?analytic hierarchy process, Likert scale and equal weights?that are then compared. Finally, scores from an MCA are input into an optimization model used to determine the optimal land-use distribution in order to maximize utility and land-use diversification according to different scenarios of funds and water availability. While our results show a spectrum of perceptions of priorities among stakeholders, there is one overriding theme that is to define a way to restore part of the rice fields to natural wetlands. These results hold true under the current climate scenario and evenmore so under an increased water scarcity scenario

Prevalence and co-infection of haemotropic mycoplasmas in Portuguese cats by real-time polymerase chain reaction

The diagnosis of feline haemoplasmosis has improved over the years, with several techniques enabling a clear and specific diagnosis, and where polymerase chain reaction (PCR) is considered as the 'gold standard'. The aim of this study was to survey the prevalence of feline haemoplasmas in 320 cats from the north-central region of Portugal by the use of real-time PCR, as well as to evaluate any associations between infection, clinical presentation and risk factors. The overall prevalence of infection by feline haemoplasmas was 43.43% (139/320), where 41.56% (133/320) corresponded to Candidatus Mycoplasma haemominutum (CMhm), 12.81% (41/320) to Mycoplasma haemofelis (Mhf), 4.38% (14/320) to Candidatus Mycoplasma haematoparvum and 1.25% (4/320) to Candidatus Mycoplasma turicensis. Almost 13% (47/320) of the samples were co-infected, with the most common co-infection being CMhm and Mhf (23.74%). Infection was found statistically significant with feline immunodeficiency/feline leukaemia virus status (P = 0.034), but no significant association was found for breed, sex, fertility status (neutered/spayed/entire), age, clinical status, living conditions (in/outdoor), anaemia status, or the presence/absence of ticks or fleas. Cats from north-central Portugal are infected with all the known feline haemoplasma species, with CMhm being the most common one. Prevalence of all feline haemoplasmas was higher than that reported previously in cats from other European countries, but similar to that described in Portugal for dogs. These data provide a better perspective regarding Mycoplasma species infection in Europe, and new information that helps us better understand feline haemoplasmosis