7,529 research outputs found
Notas sobre a biologia de Centrolabrus caeruleus Azevedo, 1999 (Teleostei: Labridae)
Centrolabrus caeruleus is a recently described littoral fish whose biology is poorly known, despite the fact that it is very abundant in the Azores. This paper presents general information about the age and growth, food and reproduction of this species. Males grow to larger sizes than females, and there are sexual differences in colour and behaviour. Preliminary von Bertalanffy growth curves are given for both sexes, based on modal analysis of the monthly length-frequency distributions. The length-weight relationship is also given. Food is dominated by small phytal invertebrates. Reproduction occurs mainly between March and June. Young of the year are seen from July on. Territorial males build algal nests where females spawn. Details of nest building, and of the courtship and spawning behaviours are given
Damage tolerance assessment by bend and shear tests of two multilayer composites: Glass fibre reinforced metal laminate and aluminium roll-bonded laminate
The damage tolerance of an aluminium roll-bonded laminate (ALH19) and a
glass fibre reinforced laminate (GLARE) (both based in Al 2024-T3) has been studied.
The composite laminates have been tested under 3-point bend and shear tests on the
interfaces to analyze their fracture behaviour. During the bend tests different fracture
mechanisms were activated for both laminates, which depend on the constituent
materials and their interfaces. The high intrinsic toughness of the pure Al 1050 layers
present in the aluminium roll-bonded laminate (ALH19), together with extrinsic
toughening mechanisms such as crack bridging and interface delamination were
responsible for the enhanced toughness of this composite laminate. On the other hand,
crack deflection by debonding between the glass fibres and the plastic resin in GLARE,
was the main extrinsic toughening mechanism present in this composite laminateFinancial support from CICYT (Project MAT2003-01172) is gratefully
acknowledged. C.M. Cepeda-Jiménez thanks the Spanish Ministry of Education and
Science for a Juan de la Cierva contract. Authors also thank Delft University of
Technology for providing the GLARE.Peer reviewe
Dopamine D 4 Receptor-Deficient Mice Display Cortical Hyperexcitability
The dopamine D(4) receptor (D(4)R) is predominantly expressed in the frontal cortex (FC), a brain region that receives dense input from midbrain dopamine (DA) neurons and is associated with cognitive and emotional processes. However, the physiological significance of this dopamine receptor subtype has been difficult to explore because of the slow development of D(4)R agonists and antagonists the selectivity and efficacy of which have been rigorously demonstrated in vivo. We have attempted to overcome this limitation by taking a multidimensional approach to the characterization of mice completely deficient in this receptor subtype. Electrophysiological current and voltage-clamp recordings were performed in cortical pyramidal neurons from wild-type and D(4)R-deficient mice. The frequency of spontaneous synaptic activity and the frequency and duration of paroxysmal discharges induced by epileptogenic agents were increased in mutant mice. Enhanced synaptic activity was also observed in brain slices of wild-type mice incubated in the presence of the selective D(4)R antagonist PNU-101387G. Consistent with greater electrophysiological activity, nerve terminal glutamate density associated with asymmetrical synaptic contacts within layer VI of the motor cortex was reduced in mutant neurons. Taken together, these results suggest that the D(4)R can function as an inhibitory modulator of glutamate activity in the FC.Fil: Rubinstein, Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; ArgentinaFil: Cepeda, Carlos. University of California at Los Angeles; Estados UnidosFil: Hurst, Raymond S.. University of California at Los Angeles; Estados UnidosFil: Flores Hernandez, Jorge. University of California at Los Angeles; Estados UnidosFil: Ariano, Marjorie A.. The Chicago Medical School; Estados UnidosFil: Falzone, Tomas Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; ArgentinaFil: Kozell, Laura B.. Oregon Health Sciences University; Estados UnidosFil: Meshul, Charles K.. Oregon Health Sciences University; Estados UnidosFil: Bunzow, James R.. Oregon Health Sciences University; Estados UnidosFil: Low, Malcolm J.. Oregon Health Sciences University; Estados UnidosFil: Levine, Michael S.. University of California at Los Angeles; Estados UnidosFil: Grandy, David K.. Oregon Health Sciences University; Estados Unido
Locais de reprodução são fator limitante para o sapo-de-barrigavermelha de Tandil (Bufonidae) nas serras dos Pampas?
The selection of breeding sites in response to temporary pond characteristics has been frequently documented in several anuran species. Small and shallow temporary ponds are usually preferred. The Tandilean red-belly toad, Melanophryniscus aff. montevidensis, is an endemic species that breeds in temporary ponds of remnants of highland grasslands in Tandilia mountain system, Buenos Aires Province, Argentina. The goals of this work are to characterize breeding sites of Tandilean red-belly toad, and to assess the availability of potential breeding sites at remnants of highland grasslands. Tandilean red-belly toad was observed using ponds and temporary creeks in valleys and slopes of mountains. The median of dimensions for the breeding sites was 8m length, 4m wide and 10cm depth (n = 40). The majority of the breeding sites were circular and of natural origin. The dominant breeding site substrates were mud and vegetation. We found 115 potential breeding sites in grassland remnants of surroundings of Tandil city, giving a density of 7.1 potential breeding sites/km2. The density of potential breeding sites in highland grasslands of Tandilia Mountains was similar in most surveyed remnants. Therefore, our results suggest that size of remnant is not affecting the breeding habitat availability.Facultad de Ciencias Naturales y Muse
Geological framework of potentialities and malfunctions in land use planning of Estorãos River Valley (Ponte de Lima – NW Portugal)
O Vale do rio Estorãos apresenta uma diversidade geológica singular, materializada em vários fulcros de interesse geológico - patrimonial e potencial ou económico. Antevêem-se possíveis óbices à valorização destes locais o que suscita a necessidade de elaboração de um quadro de ordenamento sustentável a nível municipal e regional capaz de evitar a sua depreciação e também implica a discussão da apetência potencial/patrimonial de cada fulcro previamente detectado em busca de um balanço integrado para a sustentabilidade do usufruto da unidade territorial.The Estorãos river Valley presents a singular geological diversity, materialized in many targets of geological interest – heritage interest and economic potential. Possible blockages to its adequate valorization impose the inclusion of these occurrences in a framework of municipal and regional land use, to prevent its depreciation, balancing the territorial land use with natural preservation and studying for each case the possible dichotomy between sustainable development and the preservation of environmental quality
Search for gravitational waves associated with the August 2006 timing glitch of the Vela pulsar
The physical mechanisms responsible for pulsar timing glitches are thought to excite quasinormal mode oscillations in their parent neutron star that couple to gravitational-wave emission. In August 2006, a timing glitch was observed in the radio emission of PSR B0833-45, the Vela pulsar. At the time of the glitch, the two colocated Hanford gravitational-wave detectors of the Laser Interferometer Gravitational wave observatory (LIGO) were operational and taking data as part of the fifth LIGO science run (S5). We present the first direct search for the gravitational-wave emission associated with oscillations of the fundamental quadrupole mode excited by a pulsar timing glitch. No gravitational-wave detection
candidate was found. We place Bayesian 90% confidence upper limits of 6.3 x 10^(-21) to 1.4 x 10^(-20) on the peak intrinsic strain amplitude of gravitational-wave ring-down signals, depending on which spherical harmonic mode is excited. The corresponding range of energy upper limits is 5.0 x 10^(-44) to 1.3 x 10^(-45) erg
Comparative study of the microbial diversity of bulk paddy soil of two rice fields subjected to organic and conventional farming
Two adjacent paddies of an experimental rice field, subjected to organic and conventional farming, were characterized aiming the comparative assessment of microbiological variations occurring in the bulk paddy soil over the rice cycle. This study comprehended the simultaneous characterization of general physicochemical soil properties [total carbon and nitrogen, pH (H2O and KCl), C:N ratio and water content], biochemical properties [enzymatic activities and Community Level Physiological Profiles (CLPP)], the estimation of cultivable organisms (enumeration of fast growing heterotrophic bacteria, actinomycetes and fungi) and the assessment of bacterial diversity using a culture-independent method (PCR-DGGE fingerprinting). The linkage of the parameters measured was analysed by canonical correspondence analysis (CCA). CCA ordination plots of the CLPP showed a similar pattern of microbial functional activity in both agronomic management systems, except in June. Enzymatic activity, water content and fungi counts were the main factors affecting the observed CLPP time variation. Such a variation was not expressed by the Shannon and evenness indices, which did not evidence significant differences in the bacterial and functional diversity between or within farming type over the analysed period. The cluster and CCA analyses of the DGGE profiles allowed the distinction of the bacterial communities of both paddies, with temporal variations being observed in the organically managed field but not in the conventional paddy. Enzymatic activity, pH and molinate content were the factors which most contributed to the observed variations. Altogether these results underline the functional redundancy of the rice paddy soil and evidence the temporal variations on the metabolic activity of soil, irrespective of farming type.info:eu-repo/semantics/acceptedVersio
Ameliorative effects of salt resistance on physiological parameters in the halophyte Salicornia bigelovii torr. with plant growth-promoting rhizobacteria
Salicornia bigelovii is a promising resource to cultivate under extreme climatic conditions of arid-desert regions. However, the production of Salicornia depends on the appropriate supplementation of nitrogen rich synthetic fertilizers. Application of specific halotolerant nitrogen-fixing bacteria associated with S. bigelovii could be an important practice for crop production in salt-affected regions. Seedlings of S. bigelovii were inoculated and developed with plant growth promoting rhizobacteria (Klebsiella pnseumoniae) at different salinities (0 and 0.25 M NaCl) grown under in vitro conditions. The inoculation increased growth and physiological activity at a high salinity. The major benefits of inoculation were observed on total seedlings biomass (320 and 175 g at 0 and 0.25 M NaCl, respectively) and adjacent branches of stem biomass (150 and 85 g at 0 and 0.25 M NaCl, respectively). The inoculation with Klebsiella pneumoniae also significantly improved seedlings salinity tolerance compared to the noninoculated controls. In non-salinity conditions, the inoculated seedlings enhanced the CO2 fixation and O2 evolution. The non-inoculated controls were more sensitive to salinity than inoculated seedlings exposed to salinity, as indicated by several measured parameters. Moreover, inoculated seedlings had significantly increase on proline, phenolics content, but not significant in starch compared to noninoculated controls. In conclusion, K. pneumoniae inoculation mitigates the salinity effects and promotes the Salicornia growth.Keywords: Salicornia bigelovii, Klebsiella pneumoniae, halophyte, ecotype, stress salinity. African Journal of Biotechnology Vol. 12(34), pp. 5278-528
Expression of a MHC class II transgene determines both superantigenicity and susceptibility to mammary tumor virus infection.
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