New freshwater sponges from Amazonian waters

Four species of freshwater sponges have their first register of occurrence for Amazonian waters upon specimens collected from Culuene and Sete de Setembro Rivers (Xingú basin), Tapirapés River (Araguaia basin) and Cuieiras River. Trochospongilla pennsylvanica (POTTS 1882) and Trochospongilla variabilis BONETTO & EZCURRA DE DRAGO (1973) occurred as minute specimens inside large sponges of the genus Metania GRAY (1867) or of the genus Drulia GRAY (1867). T. pennsylvanica has its first register of occurrence for the Neotropical region. Spongilla spoliata n. sp. resembles Spongilla inarmata ANNADALE (1918) and Spongilla aspinosa POTTS (1880) but is readily separated from these two species on account of the characteristic spines on its microscleres. Radiospongilla amazonensis n. sp. differs from its congeners by the particular characteristics of its megascleres and gemmoscleres

The Electron Temperature Gradient in the Galactic Disk

We derive the electron temperature gradient in the Galactic disk using a sample of HII regions that spans Galactocentric distances 0--17 kpc. The electron temperature was calculated using high precision radio recombination line and continuum observations for more than 100 HII regions. Nebular Galactocentric distances were calculated in a consistent manner using the radial velocities measured by our radio recombination line survey. The large number of nebulae widely distributed over the Galactic disk together with the uniformity of our data provide a secure estimate of the present electron temperature gradient in the Milky Way. Because metals are the main coolants in the photoionized gas, the electron temperature along the Galactic disk should be directly related to the distribution of heavy elements in the Milky Way. Our best estimate of the electron temperature gradient is derived from a sample of 76 sources for which we have the highest quality data. The present gradient in electron temperature has a minimum at the Galactic Center and rises at a rate of 287 +/- 46 K/kpc. There are no significant variations in the value of the gradient as a function of Galactocentric radius or azimuth. The scatter we find in the HII region electron temperatures at a given Galactocentric radius is not due to observational error, but rather to intrinsic fluctuations in these temperatures which are almost certainly due to fluctuations in the nebular heavy element abundances. Comparing the HII region gradient with the much steeper gradient found for planetary nebulae suggests that the electron temperature gradient evolves with time, becoming flatter as a consequence of the chemical evolution of the Milky Way's disk.Comment: 43 pages, 9 figures (accepted for publication in the ApJ

Stellar parameters for stars of the CoRoT exoplanet field

Aims:To support the computation and evolutionary interpretation of periods associated with the rotational modulation, oscillations, and variability of stars located in the CoRoT fields, we are conducting a spectroscopic survey for stars located in the fields already observed by the satellite. These observations allow us to compute physical and chemical parameters for our stellar sample. Method: Using spectroscopic observations obtained with UVES/VLT and Hydra/Blanco, and based on standard analysis techniques, we computed physical and chemical parameters ($T_{\rm{eff}}$, $\log \,(g)$, $\rm{[Fe/H]}$, $v_{\rm{mic}}$, $v_{\rm{rad}}$, $v \sin \,(i)$, and $A(\rm{Li})$) for a large sample of CoRoT targets. Results: We provide physical and chemical parameters for a sample comprised of 138 CoRoT targets. Our analysis shows the stars in our sample are located in different evolutionary stages, ranging from the main sequence to the red giant branch, and range in spectral type from F to K. The physical and chemical properties for the stellar sample are in agreement with typical values reported for FGK stars. However, we report three stars presenting abnormal lithium behavior in the CoRoT fields. These parameters allow us to properly characterize the intrinsic properties of the stars in these fields. Our results reveal important differences in the distributions of metallicity, $T_{\rm eff}$, and evolutionary status for stars belonging to different CoRoT fields, in agreement with results obtained independently from ground-based photometric surveys. Conclusions: Our spectroscopic catalog, by providing much-needed spectroscopic information for a large sample of CoRoT targets, will be of key importance for the successful accomplishment of several different programs related to the CoRoT mission, thus it will help further boost the scientific return associated with this space mission.Comment: 43 pages, 17 figures, accepted for publication in A&

Carrier relaxation in GaAs v-groove quantum wires and the effects of localization

Carrier relaxation processes have been investigated in GaAs/AlGaAs v-groove quantum wires (QWRs) with a large subband separation (46 meV). Signatures of inhibited carrier relaxation mechanisms are seen in temperature-dependent photoluminescence (PL) and photoluminescence-excitation (PLE) measurements; we observe strong emission from the first excited state of the QWR below ~50 K. This is attributed to reduced inter-subband relaxation via phonon scattering between localized states. Theoretical calculations and experimental results indicate that the pinch-off regions, which provide additional two-dimensional confinement for the QWR structure, have a blocking effect on relaxation mechanisms for certain structures within the v-groove. Time-resolved PL measurements show that efficient carrier relaxation from excited QWR states into the ground state, occurs only at temperatures > 30 K. Values for the low temperature radiative lifetimes of the ground- and first excited-state excitons have been obtained (340 ps and 160 ps respectively), and their corresponding localization lengths along the wire estimated.Comment: 9 pages, 8 figures, submitted to Phys. Rev. B Attempted to correct corrupt figure

Efeito das auxinas 2,4-D e TDZ na indução da embriogênese somática em Uncaria tomentosa a partir de ápice caulinar.

O objetivo desse trabalho foi avaliar o efeito das auxinas 2,4-D e TDZ na indução da embriogênese somática utilizando ápice caulinar de U. tomentosa

AVALIAÇÃO DE IMPACTOS AMBIENTAIS NA COLHEITA MECANIZADA EM FOMENTOS FLORESTAIS

MACIEL, Cássio Maggi Salvia. Avaliação de impactos ambientais na colheita mecanizada em fomentos florestais. 2015. Dissertação (Mestrado em Ciências Florestais) Universidade Federal do Espírito Santo, Jerônimo Monteiro, ES. Orientador: Prof. Dr. Luciano José Minette. Coorientadores: Prof. Dr. Luís Carlos de Freitas e Nílton Cezar Fiedler. Paralelamente à crescente busca por tecnologias mais avançadas e eficientes no processo de colheita florestal, a conscientização pela preservação dos recursos naturais aumentou de forma significativa por todo o mundo. Com isso, este trabalho teve como objetivo identificar e avaliar quali-quantitativamente os principais impactos ambientais oriundos do processo de colheita florestal no subsistema harvester e forwarder realizado em propriedades fomentadas, buscando delinear possíveis medidas mitigadoras ou potencializadoras. Para tanto utilizou-se de uma escala de magnitude e um questionário que foi aplicado a funcionários experientes em fomentos florestais nos estados de Santa Catarina e Paraná. Através de um check-list descritivo os impactos foram discutidos e avaliados qualitativamente e por meio do cruzamento da reversibilidade do impacto com seu resultado de magnitude obteve-se o seu valor de importância. Os impactos no meio antrópico mostraram-se de maior relevância no estudo, pois apesar do número reduzido de impactos relacionados estes obtiveram os maiores valores de magnitude e importância. O meio físico apresentou elevada ocorrência de impactos de média importância, requerendo atenção também pelo fato de possuir impactos de controle estratégico que evitam a ocorrência de outros danos ambientais. O meio biótico mostrou-se menos preocupante, com a predominância de impactos de baixa magnitude, reversíveis e de pequena importância. A maioria dos impactos apresentaram-se negativos, de ordem direta, de abrangência territorial regional, que ocorrem em curto prazo, com duração permanente e/ou indefinida e que são reversíveis com a possibilidade de uso de medidas mitigadoras ou potencializadoras

Thermal instability of an expanding dusty plasma with equilibrium cooling

We present an analysis of radiation induced instabilities in an expanding plasma with considerable presence of dust particles and equilibrium cooling. We have shown that the equilibrium expansion and cooling destabilize the radiation condensation modes and the presence of dust particles enhances this effect. We have examined our results in the context of ionized, dusty-plasma environments such as those found in planetary nebulae (PNe). We show that due to the non-static equilibrium and finite equilibrium cooling, small-scale localized structures formed out of thermal instability, become transient, which agrees with the observational results. The dust-charge fluctuation is found to heavily suppress these instabilities, though in view of non-availability of convincing experimental data, a definitive conclusion could not be made.Comment: 23 pages, 14 figure

Embriogênese somática em Uncaria tomentosa a partir de folhas imaturas.

O objetivo desse trabalho foi induzir a embriogênese somática a partir de folhas imaturas de U. tomentosa de plântulas germinadas in vitro