No-horizon theorem for spacetimes with spacelike G1 isometry groups

We consider four-dimensional spacetimes $(M,{\mathbf g})$ which obey the Einstein equations ${\mathbf G}={\mathbf T}$, and admit a global spacelike $G_{1}={\mathbb R}$ isometry group. By means of dimensional reduction and local analyis on the reduced (2+1) spacetime, we obtain a sufficient condition on ${\mathbf T}$ which guarantees that $(M,{\mathbf g})$ cannot contain apparent horizons. Given any (3+1) spacetime with spacelike translational isometry, the no-horizon condition can be readily tested without the need for dimensional reduction. This provides thus a useful and encompassing apparent horizon test for $G_{1}$-symmetric spacetimes. We argue that this adds further evidence towards the validity of the hoop conjecture, and signals possible violations of strong cosmic censorship.Comment: 8 pages, LaTeX, uses IOP package; published in Class. Quantum Gra

Modeling the spectrum of gravitational waves in the primordial Universe

Recent observations from type Ia Supernovae and from cosmic microwave background (CMB) anisotropies have revealed that most of the matter of the Universe interacts in a repulsive manner, composing the so-called dark energy constituent of the Universe. The analysis of cosmic gravitational waves (GW) represents, besides the CMB temperature and polarization anisotropies, an additional approach in the determination of parameters that may constrain the dark energy models and their consistence. In recent work, a generalized Chaplygin gas model was considered in a flat universe and the corresponding spectrum of gravitational waves was obtained. The present work adds a massless gas component to that model and the new spectrum is compared to the previous one. The Chaplygin gas is also used to simulate a $\Lambda$-CDM model by means of a particular combination of parameters so that the Chaplygin gas and the $\Lambda$-CDM models can be easily distinguished in the theoretical scenarios here established. The lack of direct observational data is partialy solved when the signature of the GW on the CMB spectra is determined.Comment: Proc. of the Conference on Magnetic Fields in the Universe: from laboratories and stars to primordial structures, AIP(NY), eds. E. M. de Gouveia Dal Pino, G. Lugones & A. Lazarian (2005), in press. (8 pages, 11 figures

Phases of massive scalar field collapse

We study critical behavior in the collapse of massive spherically symmetric scalar fields. We observe two distinct types of phase transition at the threshold of black hole formation. Type II phase transitions occur when the radial extent $(\lambda)$ of the initial pulse is less than the Compton wavelength ($\mu^{-1}$) of the scalar field. The critical solution is that found by Choptuik in the collapse of massless scalar fields. Type I phase transitions, where the black hole formation turns on at finite mass, occur when $\lambda \mu \gg 1$. The critical solutions are unstable soliton stars with masses \alt 0.6 \mu^{-1}. Our results in combination with those obtained for the collapse of a Yang-Mills field~{[M.~W. Choptuik, T. Chmaj, and P. Bizon, Phys. Rev. Lett. 77, 424 (1996)]} suggest that unstable, confined solutions to the Einstein-matter equations may be relevant to the critical point of other matter models.Comment: 5 pages, RevTex, 4 postscript figures included using psfi

Aspectos técnicos da cultura da framboeseira.

bitstream/CPACT/9252/1/documento_120.pdf; bitstream/item/32425/1/documento-120.pd

Espécies frutíferas nativas do Sul do Brasil.

bitstream/item/33526/1/documento-129.pd

Effect of a nuclear polyhedrosis virus on Spodoptera frugiperda (Smith) (Lepidoptera:noctuidae) larvae, its damage and yield of maize crop.

The efficiency of Baculovirus in a wettable powder formulation to control the fall armyworm Spodoptera frugiperda (Smith) was evaluated using variations of the recommended dose of 50 grams per hectare (2.5 x 1011 polyhedron inclusion bodies - PIB ha-1): 50 or 100 g ha-1 applied once, and variations of two applications at seven-day intervals, of 25+25, 25 + 50, 50+25 and 50+50 g ha-1, compared to untreated plots. The treatments were arranged in a randomized complete block design with six replications. Each plant at 6-8 or 8-10-leaf growth stages, was artificially infested with 10 newly hatched larvae. The virus suspension (300 L ha-1) was applied 24 hours after larvae infestation using a back-pack-manual sprayer at 40 PSI (2.8 kg cm-2) and a regular flat fan nozzle. Larval mortality rate obtained from plots with the application of 50 g of Baculovirus wettable formulation ha-1, at once (96.2%), was significantly higher than that obtained with the application of 25+25 g ha-1 (85.3%) or 25 + 50 g ha-1 (87.8%). However, it was lower than that obtained from the other virus treatments, which had no significant difference among them (mean of 99.2%). The damage caused by S. frugiperda on the leaves of plants of untreated plots (average of 4.5 in an visual scale from 1 to 5) was significantly different from that observed in plots sprayed with virus (1.75 to 2.33). Plants protected with the virus produced significantly higher yield (mean of 7,577 kg ha-1) than plants unprotected (6,140 kg ha-1), that is, 23.4% higher

Adaptability and stability in rubber tree progenies under different environmental conditions.

The aim of this work was to select progenies with high adaptability and stability from the dry rubber yield (PBS), of genotypes from a three-year-old rubber tree population, installed in three different locations (Selvíria, MS, Votuporanga, SP and Colina, SP), by the MHPRVG (Harmonic mean of the relative performance of the genetic value) method predicted by BLUP. The progenies were installed in a randomized block design with 30 treatments (progenies), three replications and 10 plants per plot, with spacing of 3.00 x 3.00 m (Selvíria, MS) and 1.50 x 1.50 m (Colina, SP and Votuporanga, SP). The PBS presented considerable genetic coefficient variability, ranging from 23.03 to 27.82% and average heritability ranging from 0.47 to 0.99, indicating the high value of the progeny tests in rubber tree breeding programs. The MHPRVG method provided a genetic gain ranging from 11 to 38% in 10 progenies to the PBS and allowed the selection of progenies with high predicted yield potential