2,100 research outputs found
Proto-Brown Dwarf Disks as Products of Protostellar Disk Encounters
The formation of brown dwarfs via encounters between proto-stars has been
confirmed with high-resolution numerical simulations with a restricted
treatment of the thermal conditions. The new results indicate that young brown
dwarfs (BDs) formed this way are disk-like and often reside in multiple
systems. The newly-formed proto-BDs disks are up to 18 AU in size and spin
rapidly making small-scale bipolar outflows, fragmentation and the possible
formation of planetary companions likely as have recently been observed for
BDs. The object masses range from 2 to 73 Jupiter masses, distributed in a
manner consistent with the observed sub-stellar initial mass function. The
simulations usually form multiple BDs on eccentric orbits about a star. One
such system was hierarchical, a BD binary in orbit around a star, which may
explain recently observed hierarchical systems. One third of the BDs were
unbound after a few thousand years and interactions among orbiting BDs may
eject more or add to the number of binaries. Improvements over prior work
include resolution down to a Jupiter mass, self-consistent models of the
vertical structure of the initial disks and careful attention to avoid
artificial fragmentation.Comment: 4 pages, 3 figures, accepted for publication in ApJ Letter
Gradient Photonic Materials Based on OneâDimensional Polymer Photonic Crystals
In nature, animals such as chameleons are wellâknown for the complex color patterns of their skin and the ability to adapt and change the color by manipulating sophisticated photonic crystal systems. Artificial gradient photonic materials are inspired by these color patterns. A concept for the preparation of such materials and their function as tunable mechanochromic materials is presented in this work. The system consists of a 1D polymer photonic crystal on a centimeter scale on top of an elastic poly(dimethylsiloxane) substrate with a gradient in stiffness. In the unstrained state, this system reveals a uniform red reflectance over the entire sample. Upon deformation, a gradient in local strain of the substrate is formed and transferred to the photonic crystal. Depending on the magnitude of this local strain, the thickness of the photonic crystal decreases continuously, resulting in a positionâdependent blue shift of the reflectance peak and hence the color in a rainbowâlike fashion. Using more sophisticated hardâsoftâhardâsoftâhard gradient elastomers enables the realization of stripeâlike reflectance patterns. Thus, this approach allows for the tunable formation of reflectance gradients and complex reflectance patterns. Envisioned applications are in the field of mechanochromic sensors, telemedicine, smart materials, and metamaterials
The role of ECL2 in CGRP receptor activation: a combined modelling and experimental approach
The calcitonin gene-related peptide (CGRP) receptor is a complex of a calcitonin receptor-like receptor (CLR), which is a family B G-protein-coupled receptor (GPCR) and receptor activity modifying protein 1. The role of the second extracellular loop (ECL2) of CLR in binding CGRP and coupling to Gs was investigated using a combination of mutagenesis and modelling. An alanine scan of residues 271â294 of CLR showed that the ability of CGRP to produce cAMP was impaired by point mutations at 13 residues; most of these also impaired the response to adrenomedullin (AM). These data were used to select probable ECL2-modelled conformations that are involved in agonist binding, allowing the identification of the likely contacts between the peptide and receptor. The implications of the most likely structures for receptor activation are discussed.</jats:p
Annular pancreas: endoscopic and pancreatographic findings from a tertiary referral ERCP center
Background and Aims
Annular pancreas is a congenital anomaly whereby pancreatic tissue encircles the duodenum. Current knowledge of endoscopic findings of annular pancreas is limited to small case series. The aim of this study was to describe the endoscopic and pancreatographic findings of patients with annular pancreas at a large tertiary care ERCP center.
Methods
This is a retrospective observational study. Our Institutional Review Boardâapproved, prospectively collected ERCP database was queried for cases of annular pancreas. The electronic medical records were searched for patient and procedure-related data.
Results
From January 1, 1994, to December 31, 2016, 46 patients with annular pancreas underwent ERCP at our institution. Index ERCP was technically successful in 42 patients (91.3%), and technical success was achieved in all 46 patients (100%) after 2 attempts, when required. A duodenal narrowing or ring was found in most patients (n = 39, 84.8%), yet only 2 (4.3%) had retained gastric contents. Pancreas divisum was found in 21 patients (45.7%), 18 of which were complete divisum. Pancreatobiliary neoplasia was the indication for ERCP in 7 patients (15.2%). Pancreatographic findings consistent with chronic pancreatitis were noted in 15 patients (32.6%) at the index ERCP.
Conclusion
This is the largest series describing the endoscopic and pancreatographic findings of patients with annular pancreas. We found that 45.7% of patients had concurrent pancreas divisum. Endoscopic therapy was successful in most patients at our institution after 1 ERCP, and in all patients after a second ERCP. Nearly one-third of patients had findings consistent with chronic pancreatitis at the time of index ERCP. It is unclear whether this may be a feature of the natural history of annular pancreas
EC03-1884 Wheat Disease Profiles I
This two-page, 4-color extension circular covers the disease and symptoms of wheat in Nebraska. The diseases listed are: barley yellow dwarf, soil-borne wheat mosaic, wheat streak mosaic, leaf rust, stem rust, stripe rust, tan spot, septoria leaf blotch, common root rot, crown rot, Fusarium head blight (scab)
EC02-1883 Corn Disease Profiles
This two-page, four-color extension circular covers the many diseases of corn in Nebraska. It list and describes corn diseases such as: anthracnose, common smut, bacterial stalk rot and top rot, holcus spot, Stewart\u27s Wilt, Goss\u27s bacterial wilt and blight, common rust, southern rust, and gray leaf rust
EC03-1884 Wheat Disease Profiles I
This two-page, 4-color extension circular covers the disease and symptoms of wheat in Nebraska. The diseases listed are: barley yellow dwarf, soil-borne wheat mosaic, wheat streak mosaic, leaf rust, stem rust, stripe rust, tan spot, septoria leaf blotch, common root rot, crown rot, Fusarium head blight (scab)
Nominal Logic Programming
Nominal logic is an extension of first-order logic which provides a simple
foundation for formalizing and reasoning about abstract syntax modulo
consistent renaming of bound names (that is, alpha-equivalence). This article
investigates logic programming based on nominal logic. We describe some typical
nominal logic programs, and develop the model-theoretic, proof-theoretic, and
operational semantics of such programs. Besides being of interest for ensuring
the correct behavior of implementations, these results provide a rigorous
foundation for techniques for analysis and reasoning about nominal logic
programs, as we illustrate via examples.Comment: 46 pages; 19 page appendix; 13 figures. Revised journal submission as
of July 23, 200
Compressed representation of brain genetic transcription
The architecture of the brain is too complex to be intuitively surveyable
without the use of compressed representations that project its variation into a
compact, navigable space. The task is especially challenging with
high-dimensional data, such as gene expression, where the joint complexity of
anatomical and transcriptional patterns demands maximum compression.
Established practice is to use standard principal component analysis (PCA),
whose computational felicity is offset by limited expressivity, especially at
great compression ratios. Employing whole-brain, voxel-wise Allen Brain Atlas
transcription data, here we systematically compare compressed representations
based on the most widely supported linear and non-linear methods-PCA, kernel
PCA, non-negative matrix factorization (NMF), t-stochastic neighbour embedding
(t-SNE), uniform manifold approximation and projection (UMAP), and deep
auto-encoding-quantifying reconstruction fidelity, anatomical coherence, and
predictive utility with respect to signalling, microstructural, and metabolic
targets. We show that deep auto-encoders yield superior representations across
all metrics of performance and target domains, supporting their use as the
reference standard for representing transcription patterns in the human brain.Comment: 21 pages, 5 main figures, 1 supplementary figur
Effects of Exercise and Sertraline on Measures of Coronary Heart Disease Risk in Patients With Major Depression: Results From the SMILE-II Randomized Clinical Trial
To assess the effects of supervised and home-based aerobic exercise training, and antidepressant pharmacotherapy (sertraline) on coronary heart disease (CHD) risk factors in a sample of participants with major depressive disorder (MDD)
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