8,163 research outputs found
Unclassified autoimmune pancreatitis mimicking pancreatic cancer
A 24-year-old black male presented with a 1-week obstructive jaundice and intermittent abdominal pain, with no significant weight loss and an unsuspicious abdominal exam. Blood chemistry showed a cholestatic pattern but a complete immunological and tumoral panel (anti-smooth muscle antibody, anti-mitochondrial antibody, anti-nuclear antibody, anti-neutrophil cytoplasmic antibody, anti-Smith, anti-double-stranded-DNA antibody (anti-dsDNA), complement C3/C4, carcinoembryonic antigen, CA 19-9 and IgG4) were all within normal limits. Abdominal ultrasound revealed dilatation of the intra and extra-hepatic bile ducts. CT scan showed an abnormal dilatation of the distal bile duct but no focal enlargement of the head of the pancreas. Endoscopic ultrasound suggested an inflammatory process but the magnetic resonance cholangio-pancreatography favored a neoplastic obstruction of the distal common bile duct. Fine-needle aspiration cytology was insufficient for definitive diagnosis and the patient underwent major surgery. Follow-up with mild exocrine pancreatic insufficiency treated with enzyme replacement.info:eu-repo/semantics/publishedVersio
Scaling Behavior of Driven Interfaces Above the Depinning Transition
We study the depinning transition for models representative of each of the
two universality classes of interface roughening with quenched disorder. For
one of the universality classes, the roughness exponent changes value at the
transition, while the dynamical exponent remains unchanged. We also find that
the prefactor of the width scales with the driving force. We propose several
scaling relations connecting the values of the exponents on both sides of the
transition, and discuss some experimental results in light of these findings.Comment: Revtex 3.0, 4 pages in PRL format + 5 figures (available at
ftp://jhilad.bu.edu/pub/abbhhss/ma-figures.tar.Z ) submitted to Phys Rev Let
Synthesis and properties of Co-doped titanate nanotubes and their optical sensitization with methylene blue
Here we report on a novel chemical route to synthesize homogenous cobalt
doped titanate nanotubes (CoTNT), using an amorphous Co-doped precursor. The
influence of the synthesis temperature, autoclave dwell time and metal doping
on the structural and microstructural as well as on the optical properties of
the synthesized titanate nanotubes is studied and discussed. The optical band
gaps of the CoTNT samples are red shifted in comparison with the values
determined for the undoped samples, such red shifts bringing the absorption
edge of the CoTNT samples into the visible region. CoTNT materials also
demonstrate particular high adsorption ability for methylene blue, the amount
of the adsorbed dye being higher than the one predictable for a monolayer
formation. This suggests the possibility of intercalation of the dye molecule
between the TiO6 layers of the TNT structure. It is also shown that the
methylene blue sensitized Co-doped nanostructures are highly stable under UV
radiation and present a strong and broad absorption in the visible region.Comment: 31 pages, 3 tables, 7 figure
Dynamical demixing of a binary mixture under sedimentation
We investigate the sedimentation dynamics of a binary mixture, the species of
which differ by their Stokes coefficients but are identical otherwise. We
analyze the sedimentation dynamics and the morphology of the final deposits
using Brownian dynamics simulations for mixtures with a range of sedimentation
velocities of both species. We found a threshold in the sedimentation
velocities difference above which the species in the final deposit are
segregated. The degree of segregation increases with the difference in the
Stokes coefficients or the sedimentation velocities above the threshold. We
propose a simple mean-field model that captures the main features of the
simulated deposits
Differential temporal beta‐diversity patterns of native and non‐native arthropod species in a fragmented native forest landscape
An important factor that hinders the management of non‐native species is a general lack of information regarding the biogeography of non‐natives, and, in particular, their rates of turnover. Here, we address this research gap by analysing differences in temporal beta‐diversity (using both pairwise and multiple‐time dissimilarity metrics) between native and non‐native species, using a novel time‐series dataset of arthropods sampled in native forest fragments in the Azores. We use a null model approach to determine whether temporal beta‐diversity was due to deterministic processes or stochastic colonisation and extinction events, and linear modelling selection to assess the factors driving variation in temporal beta‐diversity between plots. In accordance with our predictions, we found that the temporal beta‐diversity was much greater for non‐native species than for native species, and the null model analyses indicated that the turnover of non‐native species was due to stochastic events. No predictor variables were found to explain the turnover of native or non‐native species. We attribute the greater turnover of non‐native species to source‐sink processes and the close proximity of anthropogenic habitats to the fragmented native forest plots sampled in our study. Thus, our findings point to ways in which the study of turnover can be adapted for future applications in habitat island systems. The implications of this for biodiversity conservation and management are significant. The high rate of stochastic turnover of non‐native species indicates that attempts to simply reduce the populations of non‐native species in situ within native habitats may not be successful. A more efficient management strategy would be to interrupt source‐sink dynamics by improving the harsh boundaries between native and adjacent anthropogenic habitats.Portuguese FCT‐NETBIOME – ISLANDBIODIV grant 0003/2011.info:eu-repo/semantics/publishedVersio
Reheating induced by competing decay modes
We address the problem of studying the decay of the inflaton field to
another scalar field through parametric resonance in the case of a
coupling that involves several decay modes. This amounts to the presence of
extra harmonic terms in the perturbation of the field dynamics. For the
case of two frequencies we compute the geometry of the resonance regions, which
is significantly altered due to the presence of non-cuspidal resonance regions
associated to higher harmonics and to the emergence of instability `pockets'.
We discuss the effect of this change in the efficiency of the energy transfer
process for the simplest case of a coupling given by a combination of the two
interaction terms of homogeneous degree usually considered in the literature.
We find that the presence of higher harmonics has limited cosmological
implications.Comment: 14 pages, 4 figures Added references. Corrected typo
Meloboris insularis
JUSTIFICATION: Meloboris insularis is an endemic ichneumonid wasp species of the Azores (Portugal), having been recorded from Faial island. From the historical data, this species could have a very small Extent of Occurrence (16 km²) and Area of Occupancy (16 km²). Despite the location of its description being currently a Nature Reserve (Caldeira do Faial), it is possible that this species has declined in the past as a result of human activity. However, the present situation of this species needs to be further assessed, further research is needed into its population, distribution, threats, ecology, life history and indigenous host species. Conservation/restoration of native habitats, as well as invasive plant species control, could potentially also aid this species' conservation. Based upon the lack of recent data regarding this species population, distribution, threats, ecology and hosts, this species is assessed as Data Deficient (DD).info:eu-repo/semantics/publishedVersio
Orthonychiurus azoricus
JUSTIFICATION: Orthonychiurus azoricus is an Azorean-endemic species described from S. Miguel island (Azores, Portugal) (Jacquemart, 1974), at an unknown location. Possibly it has a very small Extent of Occurrence (EOO = 4 km²) and Area of Occupancy (AOO = 4 km²); but the present situation of this species needs to be further assessed, and further research is needed into its population, distribution, threats, ecology and life history. Conservation of native habitats and streams could potentially aid this species' conservation. Based upon the lack of data regarding this species population, distribution, threats and ecology, this species is assessed as Data Deficient (DD).info:eu-repo/semantics/publishedVersio
Atrometoides nigerrimus
JUSTIFICATION: Atrometoides nigerrimus is an endemic ichneumonid wasp species of the Azores (Portugal), being present historically (at least) on S. Miguel island. From the historical data, this species may have had a very small Extent of Occurrence (8 km²) and Area of Occupancy (8 km²), and it is possible that this species has declined in the past as a result of human activity. However, the present situation of this species needs to be further assessed, and further research is needed into its population, distribution, threats, ecology, life history and indigenous host species. Conservation/restoration of native habitats, as well as invasive plant species control, could potentially aid this species' conservation. Based upon the lack of recent data regarding this species population, distribution, threats, ecology and hosts, this species is assessed as Data Deficient (DD).info:eu-repo/semantics/publishedVersio
Chirothrips azoricus
JUSTIFICATION: Chirothrips azoricus is endemic to São Miguel (Azores, Portugal). It has a very small Extent of Occurrence (EOO = 8 km²) and Area of Occupancy (AOO = 8 km²). There is a continuing decline in the EOO, AOO, extent and quality of habitat as well as the number of mature individuals as a result of the invasions of non-native plants; and, based on this threat, the species occurs only at one location. Therefore, the species is assessed as Critically Endangered (CR). We suggest as future conservation measures: (1) regular monitoring of the species; and (2) control of invasive species, namely Hedychium gardnerianum and Clethra arborea.info:eu-repo/semantics/publishedVersio
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