Toxicity of Glyphosate on Physalaemus albonotatus (Steindachner, 1864) from Western Brazil

Amphibian declines have been reported worldwide and pesticides can negatively impact this taxonomic group. Brazil is the world’s largest consumer of pesticides, and Mato Grosso is the leader in pesticide consumption among Brazilian states. However, the effects of these chemicals on the biota are still poorly explored. The main goals of this study were to determine the acute toxicity (CL50) of the herbicide glyphosate on Physalaemus albonotatus, and to assess survivorship rates when tadpoles are kept under sub-lethal concentrations. Three egg masses of P. albonotatus were collected in Cuiabá, Mato Grosso, Brazil. Tadpoles were exposed for 96 h to varying concentrations of glyphosate to determine the CL50 and survivorship. The CL50 was 5.38 mg L-1 and there were statistically significant differences in mortality rates and the number of days that P. albonotatus tadpoles survived when exposed in different sub-lethal concentrations of glyphosate. Different sensibilities among amphibian species may be related with their historical contact with pesticides and/or specific tolerances. Further studies are required to determine the degree to which this taxonomic group is threatened by chemical contaminants

A numerical study of the spectrum and eigenfunctions on a tubular arc

The Hamiltonian for a particle constrained to move on the surface of a curved nanotube is derived using the methods of differential forms. A two-dimensional Gram-Schmidt orthonormalization procedure is employed to calculate basis functions for determining the eigenvalues and eigenstates of a tubular arc (a nanotube in the shape of a hyperbolic cosine) with several hundred scattering centers. The curvature of the tube is shown to induce bound states that are dependent on the curvature parameters and bend location of the tube.Comment: 14 pages, 5 tables, 6 figure

Curvature induced toroidal bound states

Curvature induced bound state (E < 0) eigenvalues and eigenfunctions for a particle constrained to move on the surface of a torus are calculated. A limit on the number of bound states a torus with minor radius a and major radius R can support is obtained. A condition for mapping constrained particle wave functions on the torus into free particle wave functions is established.Comment: 6 pages, no figures, Late

Charge-transfer metal-insulator transitions in the spin-one-half Falicov-Kimball model

The spin-one-half Falicov-Kimball model is solved exactly on an infinite-coordination-number Bethe lattice in the thermodynamic limit. This model is a paradigm for a charge-transfer metal-insulator transition where the occupancy of localized and delocalized electronic orbitals rapidly changes at the metal-insulator transition (rather than the character of the electronic states changing from insulating to metallic as in a Mott-Hubbard transition). The exact solution displays both continuous and discontinuous (first-order) transitions.Comment: 22 pages including 4 figures(eps), RevTe

Taxonomic bias in amphibian research : Are researchers responding to conservation need?

Amphibians are very diverse, widely distributed, and the most endangered class of vertebrates. As with other taxa, effective conservation of amphibians needs to be supported by detailed scientific knowledge. However, species rich and broadly distributed taxa are typically characterized by high variability in research effort. Our objective was therefore to understand which factors (ecological and cultural) have led some amphibian species to be more researched than others. We used two proxies of research effort: i) the total number of articles on Web of Science (WoS) that mention the scientific name (or synonyms) of each species, and; ii) the number of conservation science articles on WoS that mention the scientific name (or synonyms) of each species. These measures were used as dependent variables in zero hurdle regression models with the aim of identifying the most important factors driving species-level knowledge production. Well researched species (generally, and for conservation) tend to have a longer history of scientific research, come from countries with high scientific capacity, have large body size, and to be present in man-made habitats. Endangered species tend to be less researched, generally and for conservation, possibly because they are often more difficult to study: many endangered amphibians are restricted to small, fragmented and remote habitats in countries with low scientific capacity. We conclude with a discussion of how taxonomic biases in research effort on amphibians can be addressed given the limited funds available for conservation research.Peer reviewe

Susceptibility profiles and correlation with pneumococcal serotypes soon after implementation of the 10-valent pneumococcal conjugate vaccine in Brazil

SummaryObjectivesTo evaluate the susceptibility patterns among Streptococcus pneumoniae recovered during the years 2010–2012 and to correlate these with serotypes.MethodsPneumococci from invasive sites were serotyped by sequential multiplex PCR and/or Quellung reaction. Etest strips were used to determine the minimal inhibitory concentrations, and the Clinical and Laboratory Standards Institute (CLSI) guidelines were used for interpretation. Genetic determinants of macrolide resistance were assessed by PCR, and the occurrence of the D phenotype was analyzed following the recommendations of the CLSI.ResultsOne hundred fifty-nine S. pneumoniae were studied; most were recovered from blood and were associated with serotypes 14, 3, 4, 23F, 20, 7F, 12F, 19A, and 19F. Pneumococcal conjugate vaccine PCV7, PCV10, and PCV13 and 23-valent polysaccharide vaccine serotypes represented 38.2%, 48.7%, 64.5%, and 85.5%, respectively. β-Lactam non-susceptibility (non-meningitis) was basically related to serotype 19A. For meningitis, it was observed in 21.4% (serotypes 14, 3, 9V, 23F, and 24F). Resistance to erythromycin occurred in 8.2% and mefA was the most common macrolide genetic determinant. One isolate was resistant to levofloxacin. Non-susceptibility to trimethoprim–sulfamethoxazole was 37.7% and to tetracycline was 22.0%.ConclusionsOur population of pneumococci represents a transition era, soon after the introduction of PCV10. Non-susceptible patterns were found to be associated with classical PCV serotypes (especially serotype 14), which is still highly prevalent, and non-PCV10 ones (19A), which may disseminate, occupying the biological niche left by the vaccine serotypes

The response of male zebu calves to creep feeding, castration, diethylstilbestrol and supplental feeding on pasture

Suplementos foram dados aos bezerros machos da raça Zebu, em pasto de capim Colonião, durante períodos anterior e posterior à desmama, para determinar seu efeito sobre o comportamento do animal e as características da carcaça. O efeito da castração e implantação do dietilestilbestrol foi também estudado. A média do ganho de peso durante o período anterior à desmama e no inverno após a desmama, foi aumentada pelos suplementos quando fornecidos na quantidade de 2 kg diários, por animal. Um suplemento com alto teor em proteína foi superior ao com baixo teor em proteína durante o inverno seco, quando o pasto encontrava-se em más condições, mas esta vantagem desapareceu durante o verão seguinte. Durante o período todo de 370 dias, os bezerros recebendo suplementos pesaram uma média de ganho de peso de 30 kg mais do que os animais que não receberam suplemento. A castração reduziu a média de ganho de peso 56 g diárias por animal e o estilbestrol aumentou a média de ganho de peso de 60 g diárias por animal, de forma que a resposta ao estilbestrol foi igual aos efeitos prejudiciais da castração. Com respeito às características da carcaça, os suplementos aumentaram os rendimentos de carne e o tamanho da região do "olho do lombo", mas não teve efeito sobre a percentagem da gordura de rim ou espessura da gordura superficial. As carcaças dos novilhos tiveram uma porcentagem mais alta de gordura de rim, mas uma região do "olho do lombo" menor do que a correspondente à carcaça do animal inteiro. A implantação de estilbestrol parece não ter tido efeito sobre essas características, embora ela tenha aumentado a porcentagem do rendimento de carne.Supplements were fed to male Zebu calves grazing Colonial Guineagrass pastures during pre and post-weaning periods to determine their effect upon animal performance and carcass characteristics. The effect of castration and implantation of diethylstilbestrol was also studied. The rate of gain during the pre-weaning period and post-weaning winter period was increased by the supplements when fed at 2kg per animal per day. A high-protein supplement was superior to a low-protein supplement during the winter-dry season when the pasture was of poor quality, but this advantage disappeared during the following summer season. During the total period of 370 days, the calves receiving the supplements weighed an average of over 30kg more than animals receiving no supplement. (See Table 5). Castration reduced the rate of gain by 56g per animal per day and stilbestrol increased the rate of gain by 60g per animal per day, so that the response to stilbestrol was equal to the detrimental effects of castration (Table 11). With respect to carcass characteristics, the supplements increased the dressing percentage (Tables 13 and 14) and the size of the rib-eye area, (Table 17) but had no effect upon the percentage of kidney fat (Table 15) or thickness of surface fat (Table 16). The steer carcasses had a higher percentage of kidney fat, a greater thickness of surface fat, but a smaller rib-eye area than the corresponding bull carcasses. The implantation of stilbestrol appeared to have no effect upon these characteristics, although it did increase the dressing percentage

Multi-component Transparent Conducting Oxides: Progress in Materials Modelling

Transparent conducting oxides (TCOs) play an essential role in modern optoelectronic devices through their combination of electrical conductivity and optical transparency. We review recent progress in our understanding of multi-component TCOs formed from solid-solutions of ZnO, In2O3, Ga2O3 and Al2O3, with a particular emphasis on the contributions of materials modelling, primarily based on Density Functional Theory. In particular, we highlight three major results from our work: (i) the fundamental principles governing the crystal structures of multi-component oxide structures including (In2O3)(ZnO)n, named IZO, and (In2O3)m(Ga2O3)l(ZnO)n, named IGZO; (ii) the relationship between elemental composition and optical and electrical behaviour, including valence band alignments; (iii) the high-performance of amorphous oxide semiconductors. From these advances, the challenge of the rational design of novel electroceramic materials is discussed.Comment: Part of a themed issue of Journal of Physics: Condensed Matter on "Semiconducting Oxides". In Press (2011

Efeito do dietilestilbestrol sobre o comportamento de novilhos da raça zebu, alimentados em pastagens

The results of ten comparisons of stilbestrol-treated steers and untreated steers are reported. All steers were on pasture during the trial period, and some steers received various kinds and amounte of supplemental feeds. In each experiment, a part of the steers in each pasture or treatment were implanted with stilbestrol, with the remainder left as untreated controls. A total of 1086 steers of Zebu breeds were included in the ten experiments, and the trials were from 224 to 364 days in length. Various kinds of supplements including ground ear corn, molasses, molasses-urea, and low-protein concentrates, and feed additives had no effect upon the response to stilbestrol (P>0.25) The implantation of stilbestrol increased the average daily gain by 111 g, which represented a 22% increase over the control steers. The increase in average daily gain for the winter-dry season was 100 g and for the summer-wet season 121 g, indicating that the response to stilbestrol with respect to increasing growth rate was not greatly different for the two seasons of the year. Even though the average daily gains of the steers during the severe winter-dry season of 1961 were very low, the increase for stilbestrol averaged 96 g per steer per day (Experiments 2, 4, 5, 0, 7, 8, 10). The production of liveweight gain per ha as influenced by stilbestrol was found to increase as the productivity and carrying capacity of the pasture increased. On a Colonial Guinea grass  pasture with a carrying capacity of 1.2 steers per ha, the increase in live weight gain per hectare was 33 kg for the stilbestrol-treated steers. On a similar pasture fertilized with 200 kg of nitrogen per ha with a carrying capacity of 3.0 steers, the increase for the stilbestrol-treated steers was 117 kg of liveweight increase per hectare. In Brazil, the widespread use of stilbestrol on steers could increase the production of beef by 20%, reduce the amount of feed required to produce a kilogram of beef, shorten the period required to produce a slaughter animal and reduce the cost of production. At present prices, less than the price of 2 kg of live weight of beef is required to pay for the stilbestrol which will give an additional 40 kg of liveweight increase.Em dez experimentos separados, num total de 1.086 novilhos, o estilbestrol produziu um aumento na média de ganho de peso diário de 111 g e um aumento de 22% sobre os animais-de-controle que não receberam tratamento. O aumento na média de ganho de peso diário, durante o inverno seco, foi de 100 g por novilho e por dia e durante o verão úmido, de 121 g por novilho. Isto indica que o estilbestrol é quase tão eficaz durante os períodos de carência nutricional, como nas ocasiões em que as pastagens apresentam-se em boas condições. Uma vez que a lotação das pastagens aumentou de 1,2 a 3,0 novilhos, por hectare, como resultado da adubação nitrogenada, os novilhos tratados com estilbestrol produziram um ganho de peso vivo adicional de 33 kg/ha, quando não foi feita nenhuma aplicação de nitrogênio às pastagens, apresentando os mesmos um ganho de 117 kg/ha quando 200 kg desse elemento foram aplicados. O uso difundido do estilbestrol em novilhos destinados ao abate, no Brasil, poderia aumentar a produção de carne bovina em cerca de 20%, reduziria a quantidade de alimento necessário para produzir um quilograma de carne, abreviaria o período exigido para o abate e diminuiria o custo a produção. Aos preços atuais, um valor menor que o de 2 kg de peso vivo cobriria as despesas com o estilbestrol, o qual proporcionaria um aumento adicional de 40 kg de peso vivo por novilho

Molasses as an energy supplement for zebu steers grazing nitrogen-fertilized and unfertilized colonial guineagrass pasture

A suplementação com melaço aumentou o ganho de peso por animal em 36 quilogramas num ensaio que teve a duração de 308 dias e em 29,7 quilogramas durante um período de 374 dias, num segundo experimento. Considerando-se apenas o aumento em ganho de peso vivo por animal, foram necessários 24,8 quilogramas de melaço para cada quilograma adicional de ganho de peso vivo. Quando se atribuiu ao melaço a diminuição do consumo de pasto, e como consequência o aumento da lotação das pastagens, foram necessários 9,5 a 14,0 quilogramas de melaço para produzir um quilograma adicional de ganho de peso vivo. Fornecendo-se melaço na dose de 2 quilogramas por novilho e por dia, houve redução no consumo de pasto e, como consequência, a lotação das pastagens foi aumentada em 20 por cento. Fornecendo-se 2 quilogramas de melaço, por novilho e por dia, houve um aumento no ganho de peso vivo, por hectare, de 246 para 364 quilogramas, significando um acréscimo de 118 quilogramas. O adubo nitrogenado, na dose de 100 quilogramas de N por hectare, aumentou o teor protéico do pasto de 2,5 para 3,0 por cento. Os novilhos que consumiam pasto adubado com nitrogênio tiveram um ganho adicional de peso de 20,5 quilogramas sobre as testemunhas durante as estações secas de inverno, mas grande parte dessa vantagem desapareceu durante os verões subsequentes, de modo que a vantagem devida ao nitrogênio, no fim dos verões, foi apenas de 6,9 quilogramas por novilho. O adubo nitrogenado aumentou a quantidade de forragem produzida por hectare, a quantidade de N.D.T. por hectare, a lotação das pastagens em termos de animais-dias/ha e o ganho de peso vivo por hectare. Um quilograma de nitrogênio deu uma resposta de 1,9 quilogramas de peso vivo, como média para o período de três anos. Os efeitos combinados do adubo nitrogenado e do suplemento de melaço foram aditivos para novilhos por hectare, e ganho de peso vivo por hectare, não houve então nenhuma interação entre os dois fatores. Aqui está sendo apresentada uma razão para o emprego do método de equilíbrio. Sua aplicação em experimentos de pastejo, que estudam os fatores que influenciam, a lotação das pastagens e o rendimento da produção animal por hectare, são cuidadosamente examinados e debatidos.Molasses supplement increased the gain per animal 36 kg in a 308-day trial (Table 1) and 29.7 kg during a 364-day period in a second trial [Figure 7(a)]. If only the increase in liveweight gain per animal is considered, 24.8 kg of molasses was required for each additional kilogram of liveweight gain. When the molasses was credited for decreasing the consumption of forage and as a consequence increasing the carrying capacity of the pastures, from 9.5 to 14.0 kg of molasses was required to produce an additional kilogram of liveweight gain. Feeding molasses at the rate of 2 kg per steer per day reduced the intake of forage (Figure 8) and as a consequence increased the carrying capacity of the pastures 20 percent [Figure 9 (a)]. Feeding 2 kg of molasses per steer per day increased the liveweight gain per hectare from 246 to 364 kg. [Figure 11(a)], an increase of 118 kilograms. Nitrogen fertilizer at the rate of 100 kg N per ha. increased the protein content of the pasture forage by 2.5 to 3.0 percent (Figure 10). Steers consuming nitrogen-fertilized grass gained an additional 20.5 kg. [Figure 7(b)] over the control animals during the winter-dry seasons, but much of this advantage was lost during the subsequent summer seasons so that the advantage for nitrogen by the end of the summer was only 6.9 kg per steer. The nitrogen fertilizer increased the amount of forage produced per hectare, the amount of T.D.N. per hectare, the carrying capacity of the pastures as measured by steer days per hectare, and the liveweight gain per hectare. A kilogram of nitrogen gave a return of 1.9 kg. of liveweight as an average for the three-year period (Table 10). The combined effects of nitrogens fertilizer and molasses supplement were additive for steers per hectare and liveweight gain per hectare, and there was no interaction between the two factors. A rationale for the put-and-take method is given. Its application to grazing experiments in which factors are being studied that influence the number of animals which the pastures will support and the output of animal product per hectare are carefully examined and discussed