Finite-Size Scaling and Damage Spreading in Ising Systems with Multispin Interactions

We investigate two-dimensional Ising systems with multisping interactions of three- (m=3) and four-body terms (m=4). The application of a new type of finite-size algorithm of de Oliveira allow us to clearly distinguish a first-order transition (in the m=4 case) from a continuous one (in the m=3 one). We also study the damage spreading in these systems. In this study, a dynamical phenomenon is observed to occur at a critical point separating a chaotic phase from a frozen one. However, the width of the interval where this transition happens does not yield a conclusive evidence about the order of the phase transition.Comment: 18 pages, 6 figure

Which mechanism underlies the water-like anomalies in core-softened potentials?

Using molecular dynamics simulations we investigate the thermodynamic of particles interacting with a continuous and a discrete versions of a core-softened (CS) intermolecular potential composed by a repulsive shoulder. Dynamic and structural properties are also analyzed by the simulations. We show that in the continuous version of the CS potential the density at constant pressure has a maximum for a certain temperature. Similarly the diffusion constant, $D$, at a constant temperature has a maximum at a density $\rho_{\mathrm{max}}$ and a minimum at a density $\rho_{\mathrm{min}}<\rho_{\mathrm{max}}$, and structural properties are also anomalous. For the discrete CS potential none of these anomalies are observed. The absence of anomalies in the discrete case and its presence in the continuous CS potential are discussed in the framework of the excess entropy.Comment: 8 page

Historical biogeography of the Southeast Asian and Malesian tribe Dissochaeteae (Melastomataceae)

The region of Tropical Southeast Asia and the Malay Archipelago is a very appealing area for research due to its outstanding biodiversity, being one of the most species-rich areas in the world with high levels of endemism, and due to its complex geological history. The high number of species in tribe Dissochaeteae (Melastomataceae) and their tendency to narrow endemism make the tribe an ideal group for examining biogeographic patterns. We sampled 58 accessions spread over 42 accepted and two undescribed species of the Dissochaeteae. Two nuclear (ETS, ITS) and four chloroplast regions (ndhF, psbK-psbL, rbcL, rpl16) were used for divergence time estimation and ancestral area reconstruction. Results from the molecular dating analysis suggest that the diversity of Dissochaeteae in the Southeast Asian region resulted from a South American ancestor in the late Eocene. The ancestor of the Dissochaeteae might have migrated from South America to Southeast Asia via North America and then entered Eurasia over the North Atlantic land bridge during the Eocene. The origin and early diversification of the Dissochaeteae in Southeast Asia dates back to the middle Oligocene, and most of the genera originated during the Miocene. Indochina and Borneo are most likely the area of origin for the most recent common ancestor of the Dissochaeteae and for many of the early diverging clades of some genera within Southeast Asia.NaturalisPlant science

Nature of singularity formed by the gravitational collapse in Husain space-time with electromagnetic field and scalar field

In this work, we have investigated the outcome of gravitational collapse in Husain space-time in the presence of electro-magnetic and a scalar field with potential. In order to study the nature of the singularity, global behavior of radial null geodesics have been taken into account. The nature of singularities formed has been thoroughly studied for all possible variations of the parameters. These choices of parameters has been presented in tabular form in various dimensions. It is seen that irrespective of whatever values of the parameters chosen, the collapse always results in a naked singularity in all dimensions. There is less possibility of formation of a black hole. Hence this work is a significant counterexample of the cosmic censorship hypothesis.Comment: 9 pages, 19 figure

Inibidor Da Ação Do Etileno Na Conservação Pós-colheita De Chrysanthemum Morifolium Ramat Cv. Dragon [inhibitor Of Ethylene Action In Postharvest Conservation Of Chrysanthemum Morifolium Ramat Cv. Dragon]

The durability and postharvest quality of cut flowers are fundamental attributes in value along the production chain and in consumer satisfaction. The objective of this study was to evaluate the effect of chemical inhibitors of ethylene action on maintaining the postharvest quality of chrysanthemum stems (Chrysanthemum morifolium Ramat cv. Dragon). The experiment tested maintenance solutions with silver thiosulfate (STS) under five levels (distilled water, a 0.2 mM STS, the STS 0.2 mM + sucrose at 50 g L-1, STS at 0.4 mM; STS at 0.4 mM + sucrose at 50 g L-1), and date of sampling, for three levels (0, 3, 6 days). Three replications with two flower stems in each treatment were used in the experiment. Physical assessments were made: color, fresh mass and relative water content; chemical evaluations: reducing sugars and pigments, and qualitative assessments: turgidity, flower color, and number of buds, open flowers and partially open flowers. Treatment with 0.2 mM STS resulted in better maintenance of fresh mass of stems. The concentration of pigments and reducing sugar was higher in those treatments in which sucrose was associated. The color and relative water content were favored in treatments STS 0.2 mM and 0.4 mM. The concentration of 0.2 mM STS obtained the best results, prolonging the vase life the stems. The quality of these stems was higher, with the best assessments of water content, color and turgidity.34511841190Almeida, E.F.A., de Paiva, P.D.O., de Lima, L.C.O., Resende, M.L., Fonseca, J., Tavares, T.S., Póscolheita de copo-de-leite: Efeito de diferentes Póscolheita de copo-de-leite: Efeito de diferentes conservantes comerciais e armazenamento a frio (2008) Ciência e Agrotecnologia, 32 (4), pp. 1189-1194. , Lavras, Jul./agoLavrasBarbosa, J.G., Tavares, A.R.R., Finger, F.L., de Leite, R.A., Vida de prateleira de minicrisântemos em vaso tratados com tiossulfato de prata (2005) Bragantia, 4, p. 64. , CampinasBorochov, A., Mayak, S., Broun, R., The involvement of water stress and ethylene in senescence of cut carnations flowers (1982) Journal of Experimental Botany, 33 (137), pp. 1202-1209. , LondonBurzo, I., Dobrescu, A., The exchange of substances between some cut flowers and solutions during vase life (1995) Acta Horticulturae, 405, pp. 101-107. , AmsterdamChantrachit, T., (1999) Postharvest Physiology of Red Ginger Inflorescence (Alpinia Purpurata (VIEILL) K. Schum, , Doctor of Philosophy in Horticulturae-University of Hawaii, Hawaii, 1999Finger, F.L., Carneiro, T.F., Barbosa, J.G., Senescência pós-colheita de inflorescências de esporinha (Consolida ajacis (2004) Pesquisa Agropecuária Brasileira, 39, pp. 533-537. , BrasíliaFrancis, F.J., Analysis of anthocyanins (1982) Anthocyanins As Food Colors, pp. 182-205. , MARKAKIS,P.(Ed.),New York: AcademicHalevy, A.H., Treatments to improve water balance of cut flowers (1976) Acta Horticulturae, 64, pp. 223-230. , AmsterdamHalevy, A.H., Mayak, S., Improved of cut flower quality opening and longevity by pre-shipment treatments (1974) Acta Horticulturae, 43, pp. 335-347. , AmsterdamHassan, F., Schmidt, G., Postharvest characteristics of cut carnations as the result of chemical treatments (2005) Acta Agronomica Hungarica, 52 (2), pp. 125-132. , Akadémiai KiadóHonda, S., Nishimura, Y., Takahashi, M., Chiba, H., Kakehi, K., A manual method for spectrophotometric determination of reducing carbohydrates with 2-cyanoacetaminde (1982) Annals of Chemistry, 119, pp. 194-199. , New YorkKramer, P.J., (1983) Water Relations of Plants, p. 489. , New York: AcademicLiao, L.J., Postharvest life of cut rose flowers as affected by silver thiosulphate and sucrose (2000) Botanical Bulletin of Academic Sinica, 41, pp. 299-303. , LondonMayak, S., Senescence of cut flowers (1987) HortScience, 22 (5), pp. 863-868. , AmsterdamColor control from feeling to instrumentation (1994) Precise Color Communication, p. 49. , MINOLTA, TokyoMoraes, P.J., Cecon, P.R., Finger, F.L., Barbosa, J.G., Alvares, V.S., Efeito da refrigeração e do condicionamento com sacarose sobre a longevidade de inflorescências de Strelitzia reginae Ait (1999) Revista Brasileira De Horticultura Ornamental, 5 (2), pp. 151-156. , CampinasNowak, J., Goszczynska, M.D., Rudnicki, R.M., Storage of cut flowers and ornamental plants: Present status and future prospects (1991) Research Institute of Pomology and Floriculture, 2 (4), pp. 255-260. , Postharvest News and InformationPaulin, A., Influence of exogenous sugar on the evolution of some senescence petals (1986) Acta Horticulturae, 181, pp. 183-193. , AmsterdamVenn, H., Effects of silver salts on the ethylene production and respiration of cut carnations (1979) Acta Horticulturae, 91, pp. 99-103. , Amsterda

Gravitational Collapse in Higher Dimensional Husain Space-Time

We investigate exact solution in higher dimensional Husain model for a null fluid source with pressure $p$ and density $\rho$ are related by the following relations (i) $p=k\rho$, (ii) $p=k\rho-\frac{B(v)}{\rho^{\alpha}}$ (variable modified Chaplygin) and (iii) $p=k\rho^{\alpha}$ (polytropic). We have studied the nature of singularity in gravitational collapse for the above equations of state and also for different choices of the of the parameters $k$ and $B$ namely, (i) $k=0$, $B=$ constant (generalized Chaplygin), (ii) $B=$ constant (modified Chaplygin). It is found that the nature of singularity is independent of these choices of different equation of state except for variable Chaplygin model. Choices of various parameters are shown in tabular form. Finally, matching of Szekeres model with exterior Husain space-time is done.Comment: 12 latex pages, No figure, RevTex styl

Space-time inhomogeneity, anisotropy and gravitational collapse

We investigate the evolution of non-adiabatic collapse of a shear-free spherically symmetric stellar configuration with anisotropic stresses accompanied with radial heat flux. The collapse begins from a curvature singularity with infinite mass and size on an inhomogeneous space-time background. The collapse is found to proceed without formation of an even horizon to singularity when the collapsing configuration radiates all its mass energy. The impact of inhomogeneity on various parameters of the collapsing stellar configuration is examined in some specific space-time backgrounds.Comment: To appear in Gen. Relativ. Gra

Junction Conditions and Consequences of Quasi-Spherical Space-Time with Electro-Magnetic Field and Vaidya Matric

In this work the junction conditions between the exterior Reissner-Nordstrom-Vaidya space-time with the interior quasi-spherical Szekeres space-time have been studied for analyzing gravitational collapse in the presence of a magneto-hydrodynamic fluid undergoing dissipation in the form of heat flow. We have discussed about the apparent horizon and have evaluated the time difference between the formation of apparent horizon and central singularity.Comment: 8 latex pages, RevTex style, no figure