On wing disparity and morphological variation of the Santana Group pterosaurs

Pterosaurs were widely spread throughout the Mesozoic Era, populating the whole world. Among this great diversity, two groups are commonly found in Brazil: the Anhangueridae and Tapejaridae. These can be mainly identified by cranial synapomorphies. However, because of the fragility of the pterosaur skeleton and rarity of the fossilisation process, the fossils found are usually incomplete, which hampers a proper taxonomic identification of the specimens. The specific proportions of these two groups of pterosaurs were obtained from bibliographic data and measurements of specimens. Eight Anhangueridae-like and seven Tapejaridae were used: Anhanguera piscator, Anhanguera santanae, Anhanguera spielbergi, Araripesaurus castilhoi, Barbosania gracilisrostris and three Anhangueridae sp. indet.; Sinopterus dongi, Tapejara wellnhoferi and five Tapejaridae sp. indet. We find that proportions of the humerus, wing metacarpal, first phalanx of the wing digit, femur and tibia are sufficient to identify partial remains of Araripe pterosaurs. A principal component analysis shows that each clade has different, non-overlapping scores in the studied ratios and these can be used with precision. Specific bone ratios for fast identification of anhanguerids and tapejarids are given, opening a broader way to diagnostic fragmentary bones.

Efeito do estresse hídrico sobre a locomoção e morfologia de girinos de Leptodactylus fuscus e Physalaemus nattereri

Diversas espécies de anuros da família Leptodactylidae se reproduzem em corpos dágua sazonais, temporários e mantidos exclusivamente por chuvas. Em períodos de estiagem prolongada a poça pode secar completamente, ocasionando elevadas taxas de mortalidade de ovos e girinos dessas espécies, podendo exercer forte pressão seletiva na evolução de mecanismos de resistência e sobrevivência nas fases iniciais do desenvolvimento. Algumas espécies de girinos conseguem sobreviver cerca de cinco dias fora dágua o que pode proporcionar uma adaptação vantajosa, porque possibilita a sobrevivência dos girinos por um período que pode ser suficiente para a reincidência de novas chuvas e restabelecimento do corpo dágua. Apesar dessa capacidade de sobrevivência, pouco se sabe sobre as possíveis modificações que a desidratação pode causar na locomoção e na morfologia durante o desenvolvimento desses animais. O presente trabalho teve como objetivo avaliar o efeito do estresse hídrico: (1) no nível de sobrevivência e perda de massa corpórea; (2) no desempenho locomotor; (3) na morfologia externa (morfometria linear) e interna, analisando tanto o volume total quanto o volume visceral (estereologia); e (4) no tempo até metamorfose após o estresse. Utilizamos girinos de duas espécies de anuros, Leptodactylus fuscus (Leptodactylinae) e Physalaemus nattereri (Leiuperinae), ambas as espécies se reproduzem em corpos dágua temporários, em áreas com estação seca definida estando, portanto sujeitas as mesmas pressões seletivas. Além disso, as duas espécies apresentam modos reprodutivos diferentes, podendo apresentar diferentes graus de resistência ao estresse hídrico. Os girinos das duas espécies foram divididos em dois grupos, os que ficaram em água (grupo controle) e os que foram submetidos ao estresse hídrico (grupo tratamento), por três períodos de tempo (12, 24 e 72 horas). Houve diferenças significativas para valores de perda de massa entre os grupos controle e tratamento em ambas as espécies, sendo o grupo tratamento que mais perdeu massa corpórea em todos os períodos, além disso, quase metade dos girinos de P. nattereri morreram em 36 horas de estresse. Não houve diferenças significativas para os dados de desempenho locomotor e volume total entre os grupos testado para girinos de L. fuscus, mas houve diferenças morfometricas significantes nos componentes relacionados a cauda e no volume visceral, onde, o intestino do grupo tratamento foi menor que do controle. Já em P. nattereri, houve diferenças significativas entre os grupos testados para desempenho locomotor, volume total, morfometria da cauda e volume visceral, sendo o estomago e anexo do tratamento maior que do controle. Nossos resultados sugerem que a exposição ao estresse hídrico não afeta significativamente a morfologia e o desempenho locomotor dos girinos de L. fuscus. No entanto, girinos de P. nattereri apresentaram uma sensibilidade ao estresse hídrico prolongado, principalmente sobre o seu desempenho locomotor.

Fecundity, morphometry post embryonic growth and development of Caridina simoni Bouvier (Decapoda: Atyidae)

The fecundity, morphometry and the post embryonic development of Caridina simoni which is the commonest atyid shrimp in Sri Lanka were studied. The fecundity values ranged from 12-55. There was a linear relationship between the logarithmic values of fecundity and body length and the same relationship was obtained for body length and weight. It was seen that the developmental period of this species was less than six days and during development it passed through six zoeal stages.

Length-weight relationship, relative condition factor (Kn) and morphometry of Arius subrostratus (Valenciennes, 1840) from a coastal wetland in Kerala

The length – weight relationship and relative condition factor of the shovel nose catfish, Arius subrostratus (Valenciennes, 1840) from Champakkara backwater were studied by examination of 392 specimens collected during June to September 2008. These fishes ranged from 6 to 29 cm in total length and 5.6 to 218 g in weight. The relation between the total length and weight of Arius subrostratus is described as Log W = -1.530+2.6224 log L for males, Log W = - 2.131 + 3.0914 log L for females and Log W = - 1.742 + 2.8067 log L for sexes combined. The mean relative condition factor (Kn) values ranged from 0.75 to 1.07 for males, 0.944 to 1.407 for females and 0.96 to 1.196 for combined sexes. The length-weight relationship and relative condition factor showed that the well-being of A. subrostratus is good. The morphometric measurements of various body parts and meristic counts were recorded. The morphometric measurements were found to be non-linear and there is no significant difference observed between the two sexes. From the present investigation, the fin formula can be written as D: I, 7; P: I, 12; A: 17 – 20; C: 26 – 32. There is no change in meristic counts with the increase in body length.

Relationship Between Regional Brain Volumes and Cognitive Performance in the Healthy Aging: An MRI Study Using Voxel-Based Morphometry

The presence of cognitive impairment is a frequent complaint among elderly individuals in the general population. This study aimed to investigate the relationship between aging-related regional gray matter (rGM) volume changes and cognitive performance in healthy elderly adults. Morphometric magnetic resonance imaging (MRI) measures were acquired in a community-based sample of 170 cognitively-preserved subjects (66 to 75 years). This sample was drawn from the "Sao Paulo Ageing and Health" study, an epidemiological study aimed at investigating the prevalence and risk factors for Alzheimer's disease in a low income region of the city of Sao Paulo. All subjects underwent cognitive testing using a cross-culturally battery validated by the Research Group on Dementia 10/66 as well as the SKT (applied on the day of MRI scanning). Blood genotyping was performed to determine the frequency of the three apolipoprotein E allele variants (APOE epsilon 2/epsilon 3/epsilon 4) in the sample. Voxelwise linear correlation analyses between rGM volumes and cognitive test scores were performed using voxel-based morphometry, including chronological age as covariate. There were significant direct correlations between worse overall cognitive performance and rGM reductions in the right orbitofrontal cortex and parahippocampal gyrus, and also between verbal fluency scores and bilateral parahippocampal gyral volume (p < 0.05, familywise-error corrected for multiple comparisons using small volume correction). When analyses were repeated adding the presence of the APOE epsilon 4 allele as confounding covariate or excluding a minority of APOE epsilon 2 carriers, all findings retained significance. These results indicate that rGM volumes are relevant biomarkers of cognitive deficits in healthy aging individuals, most notably involving temporolimbic regions and the orbitofrontal cortex.

Cortical morphometry in narcolepsy with cataplexy

The sleep-wake disorder narcolepsy with cataplexy is associated with the loss of hypocretin-(orexin-) producing neurons in the lateral hypothalamus. Several studies have reported abnormal cerebral activation in patients with narcolepsy with cataplexy. It remains unclear, however, whether these functional changes are related to structural alterations, particularly at the cortical level. To quantify structural brain changes associated with narcolepsy with cataplexy, we used high-resolution T1-weighted magnetic resonance imaging (MRI) in 12 patients compared with 12 healthy participants matched for age and gender. Subcortical and regional cortical volumes were measured using a method unbiased by non-linear registration. Further whole-brain analyses were conducted, measuring cortical characteristics, such as cortical thickness and gyrification, at thousands of points across each hemisphere using validated algorithms. Statistical analyses accounted for an effect of age and gender. We observed decreased cortical volume in the left paracentral lobule and increased cortical volume in the left caudal part of the middle frontal gyrus in narcoleptic patients compared with controls. Cortical thickness in prefrontal areas was inversely correlated with the severity of narcolepsy. Further, we observed several clusters of cortical thinning in patients with childhood or adolescent onset of narcolepsy compared with patients with adult onset of the disease. Our results suggest that specific anatomical changes may differentiate subgroups of narcolepsy patients with different clinical profiles (such as varying symptom severity or different age at onset). Future studies with larger groups of sleepy patients are required to assess whether distinct patterns of anatomical changes may distinguish narcolepsy from non-hypocretin-deficient hypersomnia disorders.

The geomorphology and morphometry of the banded terrain in Hellas basin, Mars

Hellas basin is a large impact basin situated in the southern highlands of Mars. The north-western part of the basin has the lowest elevation (-7.5 km) on the planet and contains a possibly unique terrain type, which we informally call “banded terrain”. The banded terrain is made up of smooth-looking banded deposits that display signs of viscous behavior and a paucity of superimposed impact craters. In this study, we use newly acquired high spatial resolution images from the High Resolution Imaging Science Experiment (HiRISE) in addition to existing datasets to characterize the geomorphology, the morphometry and the architecture of the banded terrain. The banded terrain is generally confined to the NW edge of the Alpheus Colles plateau. The individual bands are ~3–15 km-long, ~0.3 km-wide and are separated by narrow inter-band depressions, which are ~65 m-wide and ~10 m-deep. The bands display several morphologies that vary from linear to concentric forms. Morphometric analysis reveals that the slopes along a given linear or lobate band ranges from 0.5° to 15° (average~6°), whereas the concentric bands are located on flatter terrain (average slope~2–3°). Crater-size frequency analysis yields an Amazonian-Hesperian boundary crater retention age for the terrain (~3 Gyr), which together, with the presence of very few degraded craters, either implies a recent emplacement, resurfacing, or intense erosion. The apparent sensitivity to local topography and preference for concentrating in localized depressions is compatible with deformation as a viscous fluid. In addition, the bands display clear signs of degradation and slumping at their margins along with a suite of other features that include fractured mounds, polygonal cracks at variable size-scales, and knobby/hummocky textures. Together, these features suggest an ice-rich composition for at least the upper layers of the terrain, which is currently being heavily modified through loss of ice and intense weathering, possibly by wind.

Components of learning and assessment in linear algebra

Linear algebra provides theory and technology that are the cornerstones of a range of cutting edge mathematical applications, from designing computer games to complex industrial problems, as well as more traditional applications in statistics and mathematical modelling. Once past introductions to matrices and vectors, the challenges of balancing theory, applications and computational work across mathematical and statistical topics and problems are considerable, particularly given the diversity of abilities and interests in typical cohorts. This paper considers two such cohorts in a second level linear algebra course in different years. The course objectives and materials were almost the same, but some changes were made in the assessment package. In addition to considering effects of these changes, the links with achievement in first year courses are analysed, together with achievement in a following computational mathematics course. Some results that may initially appear surprising provide insight into the components of student learning in linear algebra.