Substructure and halo density profiles in a Warm Dark Matter Cosmology

We performed a series of high-resolution simulations designed to study the substructure of Milky Way-size galactic halos (host halos) and the density profiles of halos in a warm dark matter (WDM) scenario with a non-vanishing cosmological constant. The virial masses of the host halos range from 3.5 x 10^12 to 1.7 x 10^12 solar masses and they have more than 10^5 particles each. A key feature of the WDM power spectrum is the free-streaming length R_f which fixes an additional parameter for the model of structure formation. We analyze the substructure of host halos using three R_f values: 0.2, 0.1, and 0.05 Mpc and compare results to the predictions of the cold dark matter (CDM) model. We find that guest halos (satellites) do form in the WDM scenario but are more easily destroyed by dynamical friction and tidal disruption than their counterparts in a CDM model. The small number of guest halos that we find within the virial radii of host halos at z = 0 in the WDM models is the result of a less efficient halo accretion and a higher satellite destruction rate. Under the assumption that each guest halo hosts a luminous galaxy, we find that the observed circular velocity function of satellites around the Milky Way and Andromeda is well described by the R_f = 0.1 Mpc WDM model. In the R_f = 0.1-0.2 Mpc models, the surviving subhalos at z=0 have an average concentration parameter c_1/5 which is approximately twice smaller than that of the corresponding CDM subhalos. This difference, very likely, produces the higher satellite destruction rate found in the WDM models. The density profile of host halos is well described by the NFW fit whereas guest halos show a wide variety of density profiles (abridged).Comment: Uses emulateapj.sty: 10 pages, 4 figures, ApJ accepted. Some changes have been introduced as suggested by the referee: (1) the description of the numerical simulations was sligthly modified to make it clearer, (2) the ellipticities of the host halos are now measured, and (3) the discussion section was divided in two subsections and enlarge

Avaliação da relação entre soja e produção de biodiesel.

O objetivo deste estudo foi avaliar a importância da producão de soja para o desenvolvimento do biodiesel no Brasil e o que representa o biocombustível para o mercado da oleaginosa. A análise de oferta e demanda por biodiesel revelou que as empresas apresentam capacidade produtiva para atender ao B5 e que as usinas da região sul são as mais eficientes, em relação às vendas. O estudo da expansão da produção de soja revelou que o seu cultivo está imerso em um contexto cercado por grandes movimentos e pressões por sustentabilidade ambiental. Embora o Brasil seja um grande exportador de soja ?in natura?, a tendência aponta para a evolução do volume produzido de óleo, o que, em grande parte, se deve ao aumento na produção do grão. Verificou-se que a dispersão do cultivo da soja em diferentes regiões do país, com escala de produção suficiente para atender à produção de volumes significativos de biodiesel, possibilitou combater os crônicos problemas logísticos existentes no agronegócio nacional. Por fim, a análise do Programa Nacional de Produção e Uso do Biodiesel confirmou que o óleo de soja é a matéria-prima que supre quase 80% da produção de biodiesel no Brasil. O desenvolvimento de outras fontes para a diversificação de matéria-prima para a produção de biodiesel, tais como sebo bovino, gordura de frango, algodão e mamona, possibilitará diminuir a pressão sobre a soja e tornar o negócio mais competitivo. Evaluation of the relationship between soybean and biodiesel production. Abstract. The objective of this study was to evaluate the importance of soybean production for the biodiesel development in Brazil and what the biofuel represents to the oilseed market. The analysis of biodiesel?s supply and demand has shown that companies have production capacity to attend B5 and that the plants of the south region are the most efficient in terms of sales. The study about soybean production revealed that its cultivation is immersed in an environment surrounded by great changes and pressures for environmental sustainability. Although Brazil is a great soybean exporter, the trend points to the evolution of the volume of oil producing, what, in the most, occurs due to the increase in the production of grain. It was found that the spread of soybean cultivation in different regions of the country, with sufficient production scale to attend the significant volumes of biodiesel production, became possible to combat the chronic problems in national agribusiness logistics. Finally, the analysis of the National Production and Use of Biodiesel showed that soybean oil is the raw material that supplies almost 80% of biodiesel production in Brazil. The development of other sources for diversification of feedstock for biodiesel production, such as beef tallow, chicken fat, cotton and castor beans, will allow to reduce the pressure on soybeans and to make the business more competitive

Método para avaliar a uniformidade nas fases de cria e recria em lotes de frangas para produção de ovos.

bitstream/item/59417/1/CUsersPiazzonDocuments34.pdfProjeto n. 01.02.10.406-0

Structure and Subhalo Population of Halos in a Self-Interacting Dark Matter Cosmology

We study the structure of Milky Way (MW)- and cluster-sized halos in a Lambda Cold Dark Matter (CDM) cosmology with self-interacting (SI) dark particles. The cross section per unit of particle mass has the form sigma = sig_0(1/v_100)^alpha, where sig_0 is a constant in units of cm^2/gr and v_100 is the relative velocity in units of 100 km/s. Different values for sigma with alpha= 0 or 1 were used. For small values of sigma = const. (sig_0<0.5), the core density of the halos at z=0 is typically higher at a given mass for lower values of sig_0 or, at a given sig_0, for lower masses. For values of sig_0 as high as 3.0, the halos may undergo the gravothermal catastrophe before z=0. When alpha = 1, the core density of cluster- and MW-sized halos is similar. Using sigma = 0.5-1.0x(1/v_100), our predictions agree with the central densities and the core scaling laws of halos both inferred from the observations of dwarf and LSB galaxies and clusters of galaxies. The cumulative Vmax-functions of subhalos in MW-sized halos with (sig_0,alpha) = (0.1,0.0), (0.5,0.0) and (0.5,1.0) agree roughly with observations (luminous satellites) for Vmax > 30 km/s, while at Vmax = 20 km/s the functions are a factor 5-8 higher, similar to the CDM predictions. The halos with SI have slightly more specific angular momentum at a given mass shell and are rounder than their CDM counterparts. We conclude that the introduction of SI particles with sigma \propto 1/v_100 may remedy the cuspy core problem of the CDM cosmogony, while the subhalo population number remains similar to that of the CDM halos.Comment: To appear in ApJ, December 20, 2002. We added plots showing the evolution of the heat capacity profile for halos in the core expansion and gravothermal catastrophe phases. Minor changes in the text were introduce

BVRI Surface Photometry of Isolated Spiral Galaxies

A release of multicolor broad band (BVRI) photometry for a subsample of 44 isolated spirals drawn from the Catalogue of Isolated Galaxies (CIG) is presented. Total magnitudes and colors at various circular apertures, as well as some global structural/morphological parameters are estimated. Morphology is reevaluated through optical and sharp/filtered R band images, (B-I) color index maps, and archive near-IR JHK images from the Two-Micron Survey. The CAS structural parameters (Concentration, Asymmetry, and Clumpiness) were calculated from the images in each one of the bands. The fraction of galaxies with well identified optical/near-IR bars (SB) is 63%, while a 17% more shows evidence of weak or suspected bars (SAB). The sample average value of the maximum bar ellipticity is 0.4. Half of the galaxies in the sample shows rings. We identify two candidates for isolated galaxies with disturbed morphology. The structural CAS parameters change with the observed band, and the tendencies they follow with the morphological type and global color are more evident in the redder bands. In any band, the major difference between our isolated spirals and a sample of interacting spirals is revealed in the A-S plane. A deep and uniformly observed sample of isolated galaxies is intended for various purposes including (i) comparative studies of environmental effects, (ii) confronting model predictions of galaxy evolution and (iii) evaluating the change of galaxy properties with redshift.Comment: 44 pages, 9 figures and 7 tables included. To appear in The Astronomical Journal. For the 43 appendix figures 4.1-4.43 see http://www.astroscu.unam.mx/~avila/Figs4.1_4.43.tar.gz (7.2 Mb tar.gz file

Two summers of São Paulo drought: Origins in the western tropical Pacific

Two years of drought in Southeast Brazil have led to water shortages in São Paulo, the country's most populous city. We examine the observed drought during austral summers of 2013/2014 and 2014/2015 and the related large-scale dynamics. The 2013–2014 precipitation deficits were more concentrated in the state of São Paulo, while in 2014–2015 moderate deficits were seen throughout the region. We find that a persistent warm sea surface temperature (SST) anomaly in the western tropical Pacific Ocean was an important driver of drought via atmospheric teleconnection in the two December–February seasons. The warm SST and associated convective heating initiated a wave train across the South Pacific. The resulting anticyclonic geopotential height anomaly over the southwest Atlantic expanded the westward margin of the South Atlantic high and prevented low-pressure systems from entering southeast Brazil from midlatitudes. This mechanism suggests a hemispheric symmetry to that proposed for the recent California drought

Efficiency of use of alternative foods to inducing molt.

Projeto/Plano de Ação: 11.11.11.111