620 research outputs found
A new species of Neotropical freshwater stingray of the genus Potamotrygon Garman, 1877 from the RĂo Madrede DĂos, Peru (Chondrichthyes: Potamotrygonidae)
Potamotrygon tatianae sp. nov., is described from RĂo Madre de DĂos, Peru, upper Rio Madeira basin. The new species is distinguished from all congeners by a unique combination of characters, including its dorsal color pattern formed by a relatively slender, highly convoluted, beige to dark brown vermicular pattern, a single row of dorsal tail spines, and a relatively longer tail posterior to caudal stings. Potamotrygon tatianae sp. nov., occurs sympatrically with other species of Potamotrygon (P. falkneri, P. orbignyi and P. motoro). From the similar species P. falkneri, P. tatianae sp. nov., is further distinguished by the absence of circular, reniform, and oval spots, by its proportionally much longer tail, by having dorsal tail spines in one irregular row, and by features of the ventral lateral-line canal, dermal denticles and neurocranium. From P. orbignyi, the new species is distinct by lacking a reticulate pattern on dorsal disc and by the presence of two angular cartilages. From P. motoro, P. tatianae sp. nov., is further separated by the lack of ocelli formed by strong black concentric rings, by the more flattened aspect of its head and disc, and by having smaller and more numerous teeth. The discovery of a new species that so closely resembles a congeneric form in color pattern, a feature highly variable within the latter, highlights the importance of examining large series of individuals and of detailed morphological analyses in revealing the potentially highly cryptic nature of the diversity within the family.Potamotrygon tatianae sp. nov., Ă© descrita do RĂo Madre de DĂos, Peru, alto da bacia do RĂo Madeira. Essa nova espĂ©cie Ă© distinta de todas as espĂ©cies congenĂ©ricas por uma combinação Ășnica de caracteres, incluindo sua coloração dorsal formada por um padrĂŁo vermicular de cor bege a marrom escuro, relativamente delgado e altamente convoluto, uma Ășnica fileira mediana dorsal de espinhos sobre a cauda e uma cauda relativamente longa posteriormente aos ferrĂ”es caudais. Potamotrygon tatianae sp. nov., ocorre em simpatria com outras espĂ©cies de Potamotrygon (P. falkneri, P. orbignyi and P. motoro). Da espĂ©cie similar P. falkneri, P.tatianae sp. nov., Ă© tambĂ©m distinguida pela ausĂȘncia de manchas circulares, reniformes e ovais, por sua cauda proporcionalmente mais longa, por apresentar espinhos caudais em uma Ășnica fileira irregular e por caracteres dos canais ventrais da linha lateral, dentĂculos dĂ©rmicos e neurocrĂąnio. De P. orbignyi, a nova espĂ©cie Ă© distinguida pela ausĂȘncia de um padrĂŁo reticulado no dorso do disco e pela presença de duas cartilagens angulares. De P. motoro, P. tatianae sp. nov., Ă© separada pela ausĂȘncia de ocelos formados por anĂ©is negros concĂȘntricos intensos, pelo aspecto mais achatado da cabeça e disco e pela presença de dentes menores e mais numerosos. A descoberta de uma espĂ©cie nova que Ă© semelhante a uma outra espĂ©cie congenĂ©rica que possui um padrĂŁo de colorido dorsal semelhante, um carĂĄter muito variĂĄvel nesta espĂ©cie, ressalta a importĂąncia de examinar sĂ©ries grandes de indivĂduos e de anĂĄlises morfolĂłgicas detalhadas para revelar a natureza potencialmente crĂptica da diversidade dentro da famĂlia
Third-order nonlinear optical properties of bismuth-borate glasses measured by conventional and thermally managed eclipse Z scan
Third-order nonlinearity one order of magnitude larger than silica is measured in bismuth-borate glasses presenting a fast response (<200 fs). The results for the sign and magnitude of the nonlinearity were obtained using a combination of the eclipse Z scan with thermal nonlinearity managed Z scan, whereas the Kerr shutter technique was employed to obtain the electronic time response of the nonlinearity, all performed with 76 MHz repetition rate 150 fs pulses at 800 nm. Conventional Z scans in the picosecond regime at 532 and 1064 nm were also independently performed, yielding the values of the third-order nonlinear susceptibilities at those wavelengths. The results obtained for the femtosecond response, enhanced third-order nonlinearity of this glass (with respect to silica), place this glass system as an important tool in the development of photonics devices. Electro-optical modulators, optical switches, and frequency converters are some of the applications using second-order nonlinear properties of the Bi-glass based on the rectification model
Lee-Yang zeroes and logarithmic corrections in the Ί44 theory
The leading mean-field critical behaviour of Ï 4 4-theory is modified by multiplicative logarithmic corrections. We analyse these corrections both analytically and numerically. In particular we present a finite-size scaling theory for the Lee-Yang zeroes and temperature zeroes, both of which exhibit logarithmic corrections. On lattices from size 8 4 to 24 4, Monte-Carlo cluster methods and multi-histogram techniques are used to determine the partition function zeroes closest to the critical point. Finite-size scaling behaviour is verified and the logarithmic corrections are found to be in good agreement with our analytical predictions. 1
Cardamonin, a schistosomicidal chalcone from Piper aduncum L. (Piperaceae) that inhibits Schistosoma mansoni ATP diphosphohydrolase
AbstractBackground: Schistosomiasis is one of the world's major public health problems, and praziquantel (PZQ) is the only available drug to treat this neglected disease with an urgent demand for new drugs. Recent studies indicated that extracts from Piper aduncum L. (Piperaceae) are active against adult worms of Schistosoma mansoni, the major etiological agent of human schistosomiasis.Purpose: We investigated the in vitro schistosomicidal activity of cardamonin, a chalcone isolated from the crude extract of P. aduncum. Also, this present work describes, for the first time, the S. mansoni ATP diphosphohydrolase inhibitory activity of cardamonin, as well as, its molecular docking with S. mansoni ATPDase1, in order to investigate its mode of inhibition.Methods: In vitro schistosomicidal assays and confocal laser scanning microscopy were used to evaluate the effects of cardamonin on adult schistosomes. Cell viability was measured by MTT assay, and the S. mansoni ATPase activity was determined spectrophotometrically. Identification of the cardamonin binding site and its interactions on S. mansoni ATPDase1 were made by molecular docking experiments.Results: A bioguided fractionation of the crude extract of P. aduncum was carried out, leading to identification of cardamonin as the active compound, along with pinocembrin and uvangoletin. Cardamonin (25, 50, and 100 ”M) caused 100% mortality, tegumental alterations, and reduction of oviposition and motor activity of all adult worms of S. mansoni, without affecting mammalian cells. Confocal laser scanning microscopy showed tegumental morphological alterations and changes on the numbers of tubercles of S. mansoni worms in a dose-dependent manner. Cardamonin also inhibited S. mansoni ATP diphosphohydrolase (IC50 of 23.54 ”M). Molecular docking studies revealed that cardamonin interacts with the Nucleotide-Binding of SmATPDase 1. The nature of SmATPDase 1âcardamonin interactions is mainly hydrophobic and hydrogen bonding.Conclusion: This report provides evidence for the in vitro schistosomicidal activity of cardamonin and demonstrated, for the first time, that this chalcone is highly effective in inhibiting S. mansoni ATP diphosphohydrolase, opening the route to further studies of chalcones as prototypes for new S. mansoni ATP diphosphohydrolase inhibitors
A computational method for the identification of dengue, zika and chikungunya virus species and genotypes
In recent years, an increasing number of outbreaks of Dengue, Chikungunya and Zika viruses have been reported in Asia and the Americas. Monitoring virus genotype diversity is crucial to understand the emergence and spread of outbreaks, both aspects that are vital to develop effective prevention and treatment strategies. Hence, we developed an efficient method to classify virus sequences with respect to their species and sub-species (i.e. serotype and/or genotype). This tool provides an easy-to-use software implementation of this new method and was validated on a large dataset assessing the classification performance with respect to whole-genome sequences and partial-genome sequences.publishersversionpublishe
Renormalization group analysis of finite-size scaling in the Ăž44 model
A finite-size scaling theory for the model is derived using
renormalization group methods. Particular attention is paid to the partition
function zeroes, in terms of which all thermodynamic observables can be
expressed. While the leading scaling behaviour is identical to that of mean
field theory, there exist multiplicative logarithmic corrections too. A
non-perturbative test of these formulae in the form of a high precision Monte
Carlo analysis reveals good quantitative agreement with the analytical
predictions.Comment: 25 p + 3 PS-figures, UNIGRAZ-UTP-07-10-92 (Revision 08-10-92: only
PS-figures, which originally had too long lines exceeding 80 characters
UMA ANĂLISE DA DESTINAĂĂO DOS RECURSOS PĂBLICOS, DIRETA OU INDIRETAMENTE, AO SETOR PRIVADO DE ENSINO NO BRASIL
Mapeamento de alunos surdos matriculados na rede de ensino pĂșblica de um municĂpio de mĂ©dio porte do Estado de SĂŁo Paulo: dissonĂąncias
Behaviors associated with cows more prone to produce milk with reduced stability to ethanol test due to feeding restriction
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