762 research outputs found
Assessing the relative accuracy of coral heights reconstructed from drones and structure from motion photogrammetry on coral reefs
Low-altitude high-resolution aerial photographs allow for the reconstruction of structural properties of shallow coral reefs and the quantification of their topographic complexity. This study shows the scope and limitations of two-media (air/water) Structure from Motion—Multi-View Stereo reconstruction method using drone aerial photographs to reconstruct coral height. We apply this method in nine different sites covering a total area of about 7000 m2, and we examine the suitability of the method to obtain topographic complexity estimates (i.e., seafloor rugosity). A simple refraction correction and survey design allowed reaching a root mean square error of 0.1 m for the generated digital models of the seafloor (without the refraction correction the root mean square error was 0.2 m). We find that the complexity of the seafloor extracted from the drone digital models is slightly underestimated compared to the one measured with a traditional in situ survey method
Quantifier-Free Interpolation of a Theory of Arrays
The use of interpolants in model checking is becoming an enabling technology
to allow fast and robust verification of hardware and software. The application
of encodings based on the theory of arrays, however, is limited by the
impossibility of deriving quantifier- free interpolants in general. In this
paper, we show that it is possible to obtain quantifier-free interpolants for a
Skolemized version of the extensional theory of arrays. We prove this in two
ways: (1) non-constructively, by using the model theoretic notion of
amalgamation, which is known to be equivalent to admit quantifier-free
interpolation for universal theories; and (2) constructively, by designing an
interpolating procedure, based on solving equations between array updates.
(Interestingly, rewriting techniques are used in the key steps of the solver
and its proof of correctness.) To the best of our knowledge, this is the first
successful attempt of computing quantifier- free interpolants for a variant of
the theory of arrays with extensionality
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Altered dynamics of visual contextual interactions in Parkinson\u27s disease.
Over the last decades, psychophysical and electrophysiological studies in patients and animal models of Parkinson\u27s disease (PD), have consistently revealed a number of visual abnormalities. In particular, specific alterations of contrast sensitivity curves, electroretinogram (ERG), and visual-evoked potentials (VEP), have been attributed to dopaminergic retinal depletion. However, fundamental mechanisms of cortical visual processing, such as normalization or gain control computations, have not yet been examined in PD patients. Here, we measured electrophysiological indices of gain control in both space (surround suppression) and time (sensory adaptation) in PD patients based on steady-state VEP (ssVEP). Compared with controls, patients exhibited a significantly higher initial ssVEP amplitude that quickly decayed over time, and greater relative suppression of ssVEP amplitude as a function of surrounding stimulus contrast. Meanwhile, EEG frequency spectra were broadly elevated in patients relative to controls. Thus, contrary to what might be expected given the reduced contrast sensitivity often reported in PD, visual neural responses are not weaker; rather, they are initially larger but undergo an exaggerated degree of spatial and temporal gain control and are embedded within a greater background noise level. These differences may reflect cortical mechanisms that compensate for dysfunctional center-surround interactions at the retinal level
A megafauna pleisto-holocênica dos depósitos cavernícolas do Alto Vale do Ribeira (sul do Estado de São Paulo, Brasil)
A região do Alto Vale do Ribeira está situada no sul do Estado de São Paulo e abrange afloramentos de rochas carbonáticas pré-cambrianas com relevo cárstico bem desenvolvido, que compreendem um extenso sistema de grutas e cavernas. Os primeiros registros paleontológicos da região são do fim do século XIX e se devem a Ricardo Krone. O material fóssil descoberto por Krone só veio a ser descrito posteriormente por Ameghino, que também realizou atividades de prospecção espeleológica na região e acabou por encontrar diversas grutas e abismos com material paleontológico. Ameghino destacou o potencial da área e, desde então, novas localidades foram descobertas e projetos de exploração realizados para coleta e identificação de material fóssil. Destacam-se os trabalhos conduzidos no Abismo do Fóssil, no Abismo Ponta de Flecha, Iguatemi, entre outros. Ainda assim, no entanto, os estudos paleobiológicos realizados na região são considerados escassos. O objetivo do presente trabalho foi reunir o conhecimento existente sobre o registro de megafauna nas cavidades naturais da região e procurar mapear as localidades de ocorrência de fósseis tanto históricas como que ainda necessitam de investigação. Dessa forma pretende-se sintetizar e concentrar o conhecimento, além de disponibilizar de forma facilitada as referências das localidades para futuros estudos. A megafauna conhecida dos depósitos cavernícolas do Vale do Ribeira inclui Toxodon Owen, Eremotherium Spillmann, Catonyx (=Scelidodon) Ameghino, Hoplophorus (= Sclerocalyptus) Lund, Glyptodon Owen e Smilodon populator Lund. É discutido ainda um novo possível registro de Equidae. No mapa confeccionado com a pontuação das localidades fossilíferas, elas foram separadas em categorias entre "confirmadas" e "a confirmar", posto que foram considerados registros ainda sem verificação formal. As localidades históricas foram destacadas, assim como as localidades recém descobertas e ainda não exploradas paleontologicamente.Sesiones libresFacultad de Ciencias Naturales y Muse
Unexpected thymoma in a challenging case of hyperparathyroidism
We report the case of a woman with primary hyperparathyroidism suspected of mediastinal ectopic parathyroid adenoma revealed to be a thymoma. Our aim was to
focus on some possible criticisms in distinguishing between ectopic parathyroid and
thymus
Bioreactor With Electrically Deformable Curved Membranes for Mechanical Stimulation of Cell Cultures.
Physiologically relevant in vitro models of stretchable biological tissues, such as muscle, lung, cardiac and gastro-intestinal tissues, should mimic the mechanical cues which cells are exposed to in their dynamic microenvironment in vivo. In particular, in order to mimic the mechanical stimulation of tissues in a physiologically relevant manner, cell stretching is often desirable on surfaces with dynamically controllable curvature. Here, we present a device that can deform cell culture membranes without the current need for external pneumatic/fluidic or electrical motors, which typically make the systems bulky and difficult to operate. We describe a modular device that uses elastomeric membranes, which can intrinsically be deformed by electrical means, producing a dynamically tuneable curvature. This approach leads to compact, self-contained, lightweight and versatile bioreactors, not requiring any additional mechanical equipment. This was obtained via a special type of dielectric elastomer actuator. The structure, operation and performance of early prototypes are described, showing preliminary evidence on their ability to induce changes on the spatial arrangement of the cytoskeleton of fibroblasts dynamically stretched for 8 h
Morphometrics of teropodomorph isolated teeth material from Bauru Basin (Upper Cretaceous, Southeast Brazil)
The theropod material of the Bauru Basin consists mainly of isolated teeth, bone elements being rare, generally isolated and fragmented. The best known theropod of the unity is Pycnonemosaurus nevesi, an abelisaurid described based on some fragmented elements. An ungeal phalanx, which possesses features found in derived maniraptorans, and a scapula associated with non-avialan mariraptorans have also been recovered from this basin. The rest of the bone material collected does not show diagnostic features. Regarding the isolated teeth, many studies have been conducted to increase the taxonomic knowledge of the Bauru theropods. These works, however, have fundamentally considered qualitative (or non-measurable) characters, like general shape or presence/absence of structures. Under these circumstances the material showed affinities to Abelisauroidea, Carcharodontosauridae and Maniraptora.
Nevertheless, the evaluation of dental characters from theropod dinosaurs in terms of taxonomic identification remains controversial. Although the methodology is considered relatively efficient concerning small theropods, its effectiveness on other theropod groups is questionable. The dental morphology can vary by position in the mouth and some characters considered as diagnostic, could be, in fact, shared among taxa. The present work aimed, based on a combination of measures of the teeth (crown length, base length and width, density of denticles and derived variables like, squatness and apex location with respect to base), to obtain taxonomic sorting of the isolated material, according to a quantitative methodology. By means of multivariate analysis it was possible to recognize statistically distinct groups. We used measures of teeth associated with cranial material already been published of a variety of theropod groups, to compare with our data. In some cases, similarities could be found, while other morphotypes were completely different. We believe that this methodology offer a more reliable tool to ascertain taxonomic relationships of Bauru Basin isolated teeth material. It's an attempt to make its fossil record more informative; its interpretation better founded, and perhaps standardized.Sesiones libresFacultad de Ciencias Naturales y Muse
How to assess appearance distress and motivation in plastic surgery candidates: Italian validation of Derriford Appearance Scale 59 (DAS 59)
The Derriford Appearance Scale (DAS) 59 was specifically designed to measure psychosocial adjustment in patients with appearance problems. Previous studies using the DAS59 have proven it to be a reliable method of assessing the appearance-related quality of life after plastic surgery procedures. The aim of this study was to develop a valid and reliable Italian version of the DAS59
Registros de moluscos gastrópodes do Grupo Bauru (Bacia Bauru, Cretáceo Superior), nos estados de São Paulo e Minas Gerais, Brasil
Dentre os fósseis do Grupo Bauru (Cretáceo Superior, Bacia Bauru, Brasil), certamente os mais conhecidos são os répteis crocodilianos, quelônios e dinossaurídeos. Contudo, outros macrofósseis podem ser descritos para esses sedimentos como vegetais, ostrácodes, conchostráceos e restos de peixes. São os moluscos, entretanto, o táxon menos estudado do Grupo Bauru, sendo os poucos trabalhos existentes versando sobre a sistemática do grupo. Aqui se tenta fazer uma revisão de Gastropoda do Cretáceo da Bacia Bauru e descrição de novos locais de coleta dentro do estado de São Paulo. Para o estado de Minas Gerais são descritos táxons das ordens Mesogastropoda (Turritella sp.) e Caenogastropoda (Hydrobia sp.), ambos encontrados nas cercanias do município de Uberaba. Já para o estado de São Paulo encontram-se táxons das ordens Basommathophora (Physa aridi Mezzalira), no município de São José de Rio Preto, e Caenogastropoda (?Hydrobia prudentinensis Mezzalira), no município de Presidente Prudente. Recentes trabalhos de campo, entretanto, aumentaram a área de abrangência dos gastrópodes para o estado de São Paulo.
Duas novas espécies de Physidae são descritas para os municípios de Marília (22°20'2''S e 49º56'41''O) e Presidente Prudente (22°07'0''S e 51°26'30''O) além de uma nova espécie de Hydrobiidae no município de Presidente Prudente (22°19'88''S e 50°09'30''O). Todos os fósseis pertencem litologicamente a Formação Adamantina. A descoberta de novos pontos de coletas e de novas espécies de gastrópodes demonstra a falta e a necessidade de estudos realizados para esse grupo que apresenta um papel de indicador paleoambiental importante para o melhor entendimento das condições de deposição do Grupo Bauru.Sesiones libresFacultad de Ciencias Naturales y Muse
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