Notas sobre o comportamento de corte de Aplastodiscus arildae (Cruz & Peixoto, 1985) em um fragmento florestal urbano no sudeste do Brasil (Amphibia, Anura, Hylidae)

The courtship behavior, advertisement call, and courtship call of Aplastodiscus arildae are described based on observations realized at Parque das Mangabeiras, Belo Horizonte, Minas Gerais, Southeastern Brazil. Calling males were observed at leaves above the stream or on the litter near rivulet banks approximately all year. Female is attracted by the calling male and conducted to the subterranean nest, a different place from the calling site. The courtship event involves alternated mutual touches by the couple and calls with higher repetition rate emitted by the male. Aplastodiscus arildae presents reproductive mode with aquatic eggs deposited in subterranean nests. The advertisement call and courtship call consisted of a sequence of a unique no pulsed note, but the first presents larger interval among the calls and duration and higher dominant frequency than the last.O comportamento de corte e os cantos de anúncio e de corte de Aplastodiscus arildae são descritos com base em observações realizadas no Parque das Mangabeiras, Belo Horizonte, Minas Gerais, Sudeste do Brasil. Machos vocalizam praticamente por todo o ano, utilizando como sítios de vocalização a vegetação marginal ou o folhedo no barranco na margem de riachos. A fêmea é atraída pelo macho vocalizante, que a leva até o ninho (uma toca subterrânea), que se situa em local diferente do sítio de vocalização. No processo de condução ao ninho estão envolvidos toques mútuos entre os indivíduos e emissões de canto de corte emitidas pelo macho. Aplastodiscus arildae apresenta modo reprodutivo com ovos aquáticos depositados em ninhos subterrâneos. Os cantos de anúncio e de corte consistem de seqüências de uma única nota não pulsionada, sendo que o primeiro apresenta maior intervalo entre cantos e duração e freqüência dominante mais elevada que o segundo

Impact of Grazing Management on Productivity of Tropical Grasslands

Beef and dairy cattle enterprises from tropical pasture-based systems are notoriously of low productivity. The low soil fertility, the exploitation of native grasslands, the low genetic potential of the animals and the poor management of soil, pasture and animal components are all arguments used to explain these “low-productivity systems”. In fact, research has consistently indicated up to 50% increase in calving rate when animals grazing unfertilized pastures were supplemented with trace-mineralized salt (Table 1) but unfortunately less than 90% of Brazilian farmers use this management strategy (Tosi, 1997). However, a recent survey conducted by São Paulo State government showed that almost 90% of farmers in the State use mineralized salt as a supplement (São Paulo, 1997). Similarly, well-fertilized and managed tropical pastures frequently have enough phosphorus in plant tissues to meet mineral requirements of most grazing animal categories (Table 2) and this might represent a significant reduction in mineral supplementation costs. Nevertheless, farmers do not frequently adopt use of fertilizers. A 1997 survey revealed that only 663.000 tons of NPK fertilizers were annually applied to 90 million ha of introduced pastures in Brazil, e.g., ca. 7,4 kg of NPK fertilizer/ha of pasture per year (ANDA, 1996/1997, cited by Ferreira et al., 1999)

The solar, exoplanet and cosmological lithium problems

We review three Li problems. First, the Li problem in the Sun, for which some previous studies have argued that it may be Li-poor compared to other Suns. Second, we discuss the Li problem in planet hosting stars, which are claimed to be Li-poor when compared to field stars. Third, we discuss the cosmological Li problem, i.e. the discrepancy between the Li abundance in metal-poor stars (Spite plateau stars) and the predictions from standard Big Bang Nucleosynthesis. In all three cases we find that the "problems" are naturally explained by non-standard mixing in stars.Comment: Astrophysics and Space Science, in press. New version has one reference correcte

On the Coupling between Helium Settling and Rotation-Induced Mixing in Stellar Radiative Zones: II- Application to light elements in population I main-sequence stars

In the two previous papers of this series, we have discussed the importance of t he $\mu$-gradients due to helium settling on rotation-induced mixing, first in a n approximate analytical way, second in a 2D numerical simulation. We have found that, for slowly rotating low mass stars, a process of ``creeping paralysis" in which the circulation and the diffusion are nearly frozen may take place below the convective zone. Here we apply this theory to the case of lithium and beryll ium in galactic clusters and specially the Hyades. We take into account the rota tional braking with rotation velocities adjusted to the present observations. We find that two different cells of meridional circulation appear on the hot side of the "lithium dip" and that the "creeping paralysis" process occurs, not dir ectly below the convective zone, but deeper inside the radiative zone, at the to p of the second cell. As a consequence, the two cells are disconnected, which ma y be the basic reason for the lithium increase with effective temperature on thi s side of the dip. On the cool side, there is just one cell of circulation and t he paralysis has not yet set down at the age of the Hyades; the same modelisatio n accounts nicely for the beryllium observations as well as for the lithium ones .Comment: 13 printed pages, 10 figures. ApJ, in press (April 20, 2003

Tillering Dynamics of \u3ci\u3ePanicum maximum\u3c/i\u3e Jacq. cv. Tanzania-1 After Grazing

Tillering dynamics and tiller dry matter weight from Tanzania grass (Panicum maximum cv. Tanzania-1) were evaluated in two post-grazing stubbles (High Post-grazing Stubble – HPS-3.6 t of DM/ha and Low Post-grazing Stubble – LPS-2.3 t of DM/ha). There was no difference between post-grazing stubbles for decapitated axillary and basal remainder and new axillary tillers. The LPS presented greater number of new basal tillers. The rate of appearance of new basal and axillary tillers decreased with time after grazing. There were differences between the treatments on tiller dry matter weight, and greater values were found in the high post-graze stubble

C and N Abundances in Stars At the Base of the Red Giant Branch in M5

We present an analysis of a large sample of moderate resolution Keck LRIS spectra of subgiant (V \sim 17.2) and fainter stars in the Galactic globular cluster M5 (NGC 5904) with the goal of deriving C and N abundances. Star-to-star stochastic variations with significant range in both [C/Fe] and [N/Fe] are found at all luminosities extending to the bottom of the RGB at M_V \sim +3. Similar variations in CH appear to be present in the main sequence turnoff spectra. There is no sign of a change in the behavior of C and N with evolutionary stage over the full range in luminosity of the RGB and SGB. The C and N abundances appear strongly anti-correlated, as would be expected from the CN-cycle processing of stellar material. Yet the present stars are considerably fainter than the RGB bump, the point at which deep mixing is believed to set in. On this basis, while the observed abundance pattern is consistent with proton capture nucleosynthesis, we infer that the site of the reactions is likely not within the present sample, but rather in a population of more massive (2 -- 5 M(Sun)) now defunct stars. The range of variation of the N abundances is very large and the sum of C+N increases as C decreases. To reproduce this requires the incorporation not only of CN but also of ON-processed material. Furthermore, the existence of this correlation is quite difficult to reproduce with an external mechanism such as ``pollution'' with material processed in a more massive AGB star, which mechanism is fundamentally stochastic in nature. We therefore suggest that although the internal mixing hypothesis has serious flaws,new theoretical insights are needed and it should not be ruled out yet. (abridged)Comment: Slightly updated version to conform to that accepted by the A

Leaf Appearance and Elongation in Panicum maximum cv. Tanzania Tillers of Varying Ages

A sward may be considered as a tiller population of varying ages and sizes, and these different age groups are likely to present distinct behaviour in terms of growth and herbage production. However, there is very little information on how tiller age, in association with grazing management practices (e.g. frequency and intensity of grazing), alter morphogenetic characteristics and, therefore, herbage production. Against this background, the present experiment had the objective to evaluate leaf appearance and elongation in Panicum maximum cv. Tanzania tillers of different age groups when submitted to intermittent grazing regimes

Herbage Production of Tanzania Grass (\u3cem\u3ePanicum maximum\u3c/em\u3e cv. Tanzania) Submitted to Combinations of Frequencies and Intensities of Grazing by Cattle

Animal production from pastures is a complex process comprising three main stages: herbage growth, consumption by grazing animals and conversion into animal products (Hodgson, 1990). Utilisation is the stage where the grazier finds greater flexibility for management, probably because most processes related to harvest of the produced herbage by the grazing animals are very responsive to manipulation and control of defoliation practices. The objective of this study was to evaluate herbage production of a Panicum maximum cv. Tanzania pasture submitted to combinations of frequencies and intensities of grazing