948 resultados para Roseau commun exotique (Phragmites australis)


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Quantum field theories (QFT's) on noncommutative spacetimes are currently under intensive study. Usually such theories have world sheet noncommutativity. In the present work, instead, we study QFT's with commutative world sheet and noncommutative target space. Such noncommutativity can be interpreted in terms of twisted statistics and is related to earlier work of Oeckl [R. Oeckl, Commun. Math. Phys. 217, 451 (2001)], and others [A. P. Balachandran, G. Mangano, A. Pinzul, and S. Vaidya, Int. J. Mod. Phys. A 21, 3111 (2006); A. P. Balachandran, A. Pinzul, and B. A. Qureshi, Phys. Lett. B 634,434 (2006); A.P. Balachandran, A. Pinzul, B.A. Qureshi, and S. Vaidya, arXiv:hep-th/0608138; A.P. Balachandran, T. R. Govindarajan, G. Mangano, A. Pinzul, B.A. Qureshi, and S. Vaidya, Phys. Rev. D 75, 045009 (2007); A. Pinzul, Int. J. Mod. Phys. A 20, 6268 (2005); G. Fiore and J. Wess, Phys. Rev. D 75, 105022 (2007); Y. Sasai and N. Sasakura, Prog. Theor. Phys. 118, 785 (2007)]. The twisted spectra of their free Hamiltonians has been found earlier by Carmona et al. [J. M. Carmona, J. L. Cortes, J. Gamboa, and F. Mendez, Phys. Lett. B 565, 222 (2003); J. M. Carmona, J. L. Cortes, J. Gamboa, and F. Mendez, J. High Energy Phys. 03 (2003) 058]. We review their derivation and then compute the partition function of one such typical theory. It leads to a deformed blackbody spectrum, which is analyzed in detail. The difference between the usual and the deformed blackbody spectrum appears in the region of high frequencies. Therefore we expect that the deformed blackbody radiation may potentially be used to compute a Greisen-Zatsepin-Kuzmin cutoff which will depend on the noncommutative parameter theta.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

This paper describes four new species of the bryozoan genus Beania from the Brazilian coast. Two of them have been previously recorded in the western Atlantic as Beania hirtissima (Heller, 1867) and Beania mirabilis Johnston, 1840, respectively; they are redescribed here as Beania americana n. sp. and Beania mirabilissima n. sp. Two reticulate species, Beania correiae n. sp. and Beania metrii n. sp., are newly described. Descriptions of four other species of Beania from the region are also included: Beania australis Busk, 1852, Beania cupulariensis Osburn, 1914, Beania klugei Cook, 1968 and Beania maxilladentata Ramalho, Muricy & Taylor, 2010.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

(1Z,3Z)-Butyltelluro-o-4-methoxy-1,3-butadiene 2 was obtained by the hydrotelluration of(Z)-1-methoxy-but-1-en-3-ynes 1. The butadienyllithium 3 obtained by the Te/Li exchange reaction in the (1Z,3Z)-1-butyltelluro-4-methoxy-1.3-butadiene 2 reacted with aldehydes to form the corresponding alcohols 4a-d with total retention of configuration. The alcohols formed undergo hydrolysis, resulting in the alpha,beta,gamma,delta-unsaturated aldehydes of (E,E) configuration, which are precursors of trienes obtained from natural sources. The products of this reaction were employed in the synthesis of methyl-(2E,4E)-decadienoate 7, which is a component of the flavor principles of ripe Bartlett pears. Performing the Wittig reaction of the methyl triphenylphosphorane with the deca-(2E,4E)-dienal 5a, we were able to synthesize the undeca-(1,3E,5E)-triene 6a. This compound is a sex-pheromone component of the marine brown algae Fucus serratus, Dictyopteris plagiograma, and Dictyopteris australis. Performing the Wittig reaction of methyl triphenylphosphorane with the octa-(2E,4E)-dienal 5c, the nona-(1,3E,5E)-triene 6b was synthesized. The compound obtained is a sex-pheromone component of the marine brown alga Sargassum horneri. The octa-( 1,3E,5E)-triene 6c was easily obtained from hepta-(2E,4E)-dienal 5d by the Wittig reaction with methyl triphenylphophorane. This compound is a sex-pheromone component of the marine brown alga Fucus serratus. (C) 2010 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Objectives The first objective of this study was to evaluate the radiological impact on relatives and the environment because of outpatient treatment of differentiated thyroid carcinoma with 3.7 and 5.55 GBq of ((131)I)NaI. The second objective was to determine, analyze, and evaluate whole-body radiation dose to caregivers, the production of contaminated solid waste, and the potentiality of radiation dose and surface contamination existing inside patients` households. Methods Twenty patients were treated on an outpatient basis, taking into consideration their acceptable living conditions, interests, and willingness to comply with medical and radiation-safety guidelines. The caregivers themselves, as well as the potentiality of the radiation dose inside patients` residences, were monitored with a thermo-luminescence dosimeter. Surface contamination and contaminated solid wastes were identified and measured by using a Geiger-Muller detector. Results and discussion Twenty-six monitored individuals received accumulated effective radiation doses of less than 1.0 mSv, and only one 2.8 mSv, throughout the 7 days of measurement. The maximum registered value for the potential of radiation dose inside all living areas was 1.30 mSv. The monitored surface contamination inside patients` dwellings showed a mean value of 4.2 Bq/cm(2) for all surfaces found to be contaminated. A total of 2.5l of contaminated solid waste was generated by the patients with 3.33 MBq of all estimated activity. Conclusion This study revealed that the treatment of differentiated thyroid carcinoma with 3.7 and 5.55 GBq of ((131)I)NaI, on an outpatient basis, can be safe when overseen by qualified professionals and with an adapted radiation-protection guideline. Even considering the radioiodine activity level and the dosimetric methodology applied here, negligible human exposure and a nonmeasurable radiological impact to the human environment were found. Nucl Med Commun 30:533-541 (C) 2009 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Background: Versutoxin (delta-ACTX-Hv1) is the major component of the venom of the Australian Blue Mountains funnel web spider, Hadronyche versuta. delta-ACTX-Hv1 produces potentially fatal neurotoxic symptoms in primates by slowing the inactivation of voltage-gated sodium channels; delta-ACTX-Hv1 is therefore a useful tool for studying sodium channel function. We have determined the three-dimensional structure of delta ACTX-Hv1 as the first step towards understanding the molecular basis of its interaction with these channels. Results: The solution structure of delta-ACTX-Hv1, determined using NMR spectroscopy, comprises a core beta region containing a triple-stranded antiparallel beta sheet, a thumb-like extension protruding from the beta region and a C-terminal 3(10) helix that is appended to the beta domain by virtue of a disulphide bond. The beta region contains a cystine knot motif similar to that seen in other neurotoxic polypeptides. The structure shows homology with mu-agatoxin-l, a spider toxin that also modifies the inactivation kinetics of vertebrate voltage-gated sodium channels. More surprisingly, delta-ACTX-Hv1 shows both sequence and structural homology with gurmarin, a plant polypeptide. This similarity leads us to suggest that the sweet-taste suppression elicited by gurmarin may result from an interaction with one of the downstream ion channels involved in sweet-taste transduction. Conclusions: delta-ACTX-Hv1 shows no structural homology with either sea anemone or alpha-scorpion toxins, both of which also modify the inactivation kinetics of voltage-gated sodium channels by interacting with channel recognition site 3. However, we have shown that delta-ACTX-Hv1 contains charged residues that are topologically related to those implicated in the binding of sea anemone and alpha-scorpion toxins to mammalian voltage-gated sodium channels, suggesting similarities in their mode of interaction with these channels.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Adult and preadult Dissonus manteri attached to the gills of Plectropomus leopardus cause significant pathology in the form of large hyperplastic nodules on the afferent (leading), edges of gill filaments. Nodules result from the dual actions of parasite attachment and feeding. The host response is characterized by severe epithelial hyperplasia, supplemented by fibroplasia and inflammation. Parasites attach close to the gill arch near the base of filaments. They have little effect on gill vasculature as the maxillipeds penetrate the filament superficial to the efferent filament artery and do not interfere with the blood vessels of the secondary lamellae. Tissue proliferation is limited to the wide portion of filament 'edge' epithelium in the proximal third and also does not extend to the secondary lamellae. Nodules are most numerous towards the ends of hemibranchs and are generally absent from the central regions. Leading hemibranchs bear significantly more nodules than their trailing counterparts. Of the total number of nodules, 20.5% are located on the pseudobranchs. Distribution patterns are considered to be primarily the result of D. manteri avoiding strong water currents, although this cannot explain the difference between numbers on leading and trailing hemibranchs.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The sera of 271 pteropid bats (or flying foxes) collected from Queensland, New South Wales, Western Australia, and the Northern Territory were screened against it reference panel of 21 Leptospira spp. using the microscopic agglutination test (MAT). Sera were collected from December 1997 through August 1999. The MAT panel represented those serovars previously isolated in Australia. as well as exotic serovar found in neighboring countries. Leptospiral antibodies were detected in 75 (28%) of the sera and represented seven serovars, one of which. L. interrogans serovar cynopteri has been regarded as exotic to Australia. Sixty sera were reactive to one serovar, 12 sera were reactive to two serovars, and three sera were reactive to three serovars. The L. kirschneri serovar australis was most frequently identified (60.2%). The findings suggest a previously unrecognized role of pteropid bats in the natural history of leptospirosis. The potential exists for establishment of infection in new host species, the transmission of new serovars to known host species, and for changes in virulence of leptospires as a result of passage through these species.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Members of the flightless genus Apterotheca Gebien (Coleoptera : Tenebrionidae) are mostly restricted to the high elevation rainforests of the Wet Tropics World Heritage Area of north-eastern Australia. This region has been recognised as an 'epicentre of evolution for low vagility animals'. The genus Apterotheca is the most diverse low vagility insect taxon known in this region. Forty-four species are included here in a revision of the genus. Three of these species were previously included in Apterotheca (A. antaroides (Pascoe), A. besti (Blackburn) and A. punctipennis Carter), four were previously included in other genera (A. australis (Kulzer), comb. nov. and A. punctifrons (Gebien), comb. nov. in Apterophenus Gebien, A. costata (Buck), comb. nov. in Caxtonana Buck and A. pustulosa (Carter), comb. nov. in Austropeus Carter) and 37 are new. The monotypic genera Austropeus Carter, syn. nov. and Caxtonana Buck, syn. nov. are proposed as new synonyms of Apterotheca. A lectotype for A. punctipennis and A. besti are designated. A key to the species of Apterotheca and a phylogenetic analysis based on the morphological features of adults, as well as a discussion of character evolution, are also included. Data presented here represent the framework for future studies on the determinants of the patterns of diversity found in the Wet Tropics.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The habitat requirements of arboreal marsupials were investigated in the dry sclerophyll forests of southeast Queensland, Australia. Species richness and abundance of arboreal marsupials was correlated to the proportion of total stand basal area occupied by lemon-scented gum (Corymbia citriodora), the height of the tallest trees, and density of hollow-bearing trees. The first two factors suggested that the most productive forests were also the most suitable habitats for arboreal marsupials. Importantly, the number of hollow-bearing trees was a significant factor in determining species richness and abundance of arboreal marsupials in this study, with the maximum number of species reached at sites containing greater than or equal to4 hollow-bearing trees/ha, and maximum abundance occurring at sites with :6 hollow-bearingtrees/ha. The proportion of C. citriodora was significant for the presence of the common brushtail possum (Trichosurus vulpecula), greater glider (Petauroides volans), and the yellow-bellied glider (Petaurus australis), while understory Acacia sp. density was important for the presence of the sugar glider (Petaurus breviceps). The yellow-bellied glider was also affected by two other variables: the density of hollow-bearing trees >50 cm diameter at breast height (dbh), and the time since the last logging. Current Codes of Practice regulating the density of hollow-bearing trees and silvicultural practices in state-owned timber production forests appear to provide adequate protection for arboreal marsupials, but the recently introduced increase in timber extraction rates within state forests may be detrimental to the animals. Also, protective prescriptions do not apply to the privately owned and leasehold estates, which contain the majority of the dry sclerophyll forests in southeast Queensland.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

As a function of temperature, the layered compound K2Na[Ag(CN)213 displays dramatic variations in luminescence thermochromism with major trend changes occurring around 80 K. In order to understand these interesting optical properties, high-resolution neutron diffraction investigations were performed on a polycrystalline sample of this material in the temperature range from 1.5 to 300 K, and previous synchrotron X-ray data of Larochelle et al. (Solid State Commun. 114, 155 (2000)) were reinterpreted. The corresponding significant structural changes were found to be continuous with an anomalous increase of the monoclinic c-lattice parameter with decreasing temperature, associated with slight reorientations of two inequivalent, approximately linear N-C-Ag-C-N units. In the whole temperature range, the crystal structure is monoclinic with the space group C2/m. Based on the structural results, the major luminescence thermochromism changes around 80 K are attributed to the dominance of a back energy transfer process from low- to high-energy excitons at high temperatures. (E) 2002 Elsevier Science (USA).

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Accurate habitat mapping is critical to landscape ecological studies such as required for developing and testing Montreal Process indicator 1.1e, fragmentation of forest types. This task poses a major challenge to remote sensing, especially in mixedspecies, variable-age forests such as dry eucalypt forests of subtropical eastern Australia. In this paper, we apply an innovative approach that uses a small section of one-metre resolution airborne data to calibrate a moderate spatial resolution model (30 m resolution; scale 1:50 000) based on Landsat Thematic Mapper data to estimate canopy structural properties in St Marys State Forest, near Maryborough, south-eastern Queensland. The approach applies an image-processing model that assumes each image pixel is significantly larger than individual tree crowns and gaps to estimate crown-cover percentage, stem density and mean crown diameter. These parameters were classified into three discrete habitat classes to match the ecology of four exudivorous arboreal species (yellowbellied glider Petaurus australis, sugar glider P. breviceps, squirrel glider P. norfolcensis , and feathertail glider Acrobates pygmaeus), and one folivorous arboreal marsupial, the greater glider Petauroides volans. These species were targeted due to the known ecological preference for old trees with hollows, and differences in their home range requirements. The overall mapping accuracy, visually assessed against transects (n = 93) interpreted from a digital orthophoto and validated in the field, was 79% (KHAT statistic = 0.72). The KHAT statistic serves as an indicator of the extent that the percentage correct values of the error matrix are due to ‘true’ agreement verses ‘chance’ agreement. This means that we are able to reliably report on the effect of habitat loss on target species, especially those with a large home range size (e.g. yellow-bellied glider). However, the classified habitat map failed to accurately capture the spatial patterning (e.g. patch size and shape) of stands with a trace or sub-dominance of senescent trees. This outcome makes the reporting of the effects of habitat fragmentation more problematic, especially for species with a small home range size (e.g. feathertail glider). With further model refinement and validation, however, this moderateresolution approach offers an important, cost eff e c t i v e advancement in mapping the age of dry eucalypt forests in the region.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A continuous biostratigraphic sequence has been established, possibly from as low as the sedgwickii Biozone but certainly throughout the Telychian Stage (?sedgwickii, turriculatus, ?crispus, griestoniensis and crenulata biozones). Thirty-three taxa have been recorded, including the new genus Wandograptus wandovalensis sp. nov., the new species Pseudostreptograptus queenslandensis and the new subspecies Dictyonema paululum australis and Stimulograptus sedwickii loydelli. A number of species have been recorded from Australia for the first time: Dictyonema cf. geniculatum Bulman, Petalolithus kurcki (Rickards), Pristiograptus initialis (Kirste), Monoclimacis directa Zalasciewicz, Monograptus aff. distans (Portlock), Monograptus sartorius Törnquist, and Torquigraptus pragensis (Bouček). Nine forms have been left under open nomenclature. The type section for the Poley Cow Formation yields a griestoniensis biozone fauna close to the top, and this level can be correlated with a griestoniensis Biozone fauna in the Broken River crossing section, again just below the top of the formation. Further north, griestoniensis Biozone faunas have also been recognized, beyond Diggers Creek, and in the Quinton Formation at Top Hut, enabling a reliable time plane throughout the region. At Top Hut, the highest graptolitic strata yield a crenulata Biozone fauna; and stratigraphically lower sequences, referable to the ?sedgwickii, turriculatus and ?crispus biozones, have been established on the Broken River section. It is likely that a full Telychian (Upper Llandovery) sequence occurs in the Poley Cow and Quinton formations enabling accurate correlation with other parts of the world.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Landscape metrics are widely applied in landscape ecology to quantify landscape structure. However, many are poorly tested and require rigorous validation if they are to serve as reliable indicators of habitat loss and fragmentation, such as Montreal Process Indicator 1.1e. We apply a landscape ecology theory, supported by exploratory and confirmatory statistical techniques, to empirically test landscape metrics for reporting Montreal Process Indicator 1.1e in continuous dry eucalypt forests of sub-tropical Queensland, Australia. Target biota examined included: the Yellow-bellied Glider (Petaurus australis); the diversity of nectar and sap feeding glider species including P. australis, the Sugar Glider P. breviceps, the Squirrel Glider P. norfolcensis, and the Feathertail Glider Acrobates pygmaeus; six diurnal forest birds species; total diurnal bird species diversity; and the density of nectar-feeding diurnal bird species. Two scales of influence were considered: the stand-scale (2 ha), and a series of radial landscape extents (500 m - 2 km; 78 - 1250 ha) surrounding each fauna transect. For all biota, stand-scale structural and compositional attributes were found to be more influential than landscape metrics. For the Yellow-bellied Glider, the proportion of trace habitats with a residual element of old spotted-gum/ironbark eucalypt trees was a significant landscape metric at the 2 km landscape extent. This is a measure of habitat loss rather than habitat fragmentation. For the diversity of nectar and sap feeding glider species, the proportion of trace habitats with a high coefficient of variation in patch size at the 750 m extent was a significant landscape metric. None of the landscape metrics tested was important for diurnal forest birds. We conclude that no single landscape metric adequately captures the response of the region's forest biota per se. This poses a major challenge to regional reporting of Montreal Process Indicator 1.1e, fragmentation of forest types.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Recent laboratory studies have demonstrated that Prunus necrotic ringspot virus (PNRSV) (family Bromoviridae) can be readily transmitted when thrips and virus-bearing pollen are placed together on to test plants. For this transmission mechanism to result in stonefruit tree infection in the field, PNRSV-bearing pollen must be deposited onto surfaces of stonefruit trees on which thrips also occur. In a previous paper, we demonstrated that almost all pollen in a PNRSV-infected Japanese plum orchard in southeastern Queensland was deposited onto flowers, whereas few grains occurred on leaves and none on stems. Here, we present results of our investigation of thrips species composition, distribution and abundance on stonefruit trees in the same study area as our previous pollen deposition study. We collected a total of 2010 adult thrips from 13 orchards during the 1989, 1991 and 1992 flowering seasons of which all but 14 were in the suborder Terebrantia. Most (97.4%) terebrantian thrips were of three species, Thrips imaginis, Thrips australis and Thrips tabaci. Thrips tabaci as well as species mixtures that included T imaginis, T australis and T tabaci have been shown to transmit PNRSV via infected pollen in laboratory tests. Adult thrips were frequently collected from flowers but rarely from leaves and never from stems. Large and significant differences in numbers of T imaginis, T australis and T tabaci adults in flowers occurred among orchards and between seasons. No factor was conclusively related to thrips numbers but flowers of late-flowering stonefruit varieties tended to hold more thrips than those of early-flowering varieties. Our results indicate that the common thrips species present on stonefruit trees in the Granite Belt are also ones previously shown to transmit PNRSV via infected pollen in the laboratory and that these thrips are concentrated in stonefruit flowers where most stonefruit pollen is deposited. These results contribute to mounting circumstantial evidence that stonefruit flowers may be inoculated with PNRSV via an interaction of thrips with virus-bearing pollen and that this transmission mechanism may be an important cause of new tree infections in the field.