542 research outputs found
Thermoplastic matrix composite processing model
The effects the processing parameters pressure, temperature, and time have on the quality of continuous graphite fiber reinforced thermoplastic matrix composites were quantitatively accessed by defining the extent to which intimate contact and bond formation has occurred at successive ply interfaces. Two models are presented predicting the extents to which the ply interfaces have achieved intimate contact and cohesive strength. The models are based on experimental observation of compression molded laminates and neat resin conditions, respectively. Identified as the mechanism explaining the phenomenon by which the plies bond to themselves is the theory of autohesion (or self diffusion). Theoretical predictions from the Reptation Theory between autohesive strength and contact time are used to explain the effects of the processing parameters on the observed experimental strengths. The application of a time-temperature relationship for autohesive strength predictions is evaluated. A viscoelastic compression molding model of a tow was developed to explain the phenomenon by which the prepreg ply interfaces develop intimate contact
A solar active region loop compared with a 2D MHD model
We analyzed a coronal loop observed with the Normal Incidence Spectrometer
(NIS), which is part of the Coronal Diagnostic Spectrometer (CDS) on board the
Solar and Heliospheric Observatory (SOHO). The measured Doppler shifts and
proper motions along the selected loop strongly indicate unidirectional flows.
Analysing the Emission Measure Curves of the observed spectral lines, we
estimated that the temperature along the loop was about 380000 K. We adapted a
solution of the ideal MHD steady equations to our set of measurements. The
derived energy balance along the loop, as well as the advantages/disadvantages
of this MHD model for understanding the characteristics of solar coronal loops
are discussed.Comment: A&A in press, 10 pages, 6 figure
Spectro-Polarimetric Observation of an Emerging Flux Region: Triggering Mechanism of Ellerman Bombs
High spatial resolution observation of an emerging flux region (EFR) was done
using a vector magnetograph and a H-alpha Lyot filtergraph with Domeless Solar
Telescope at Hida Observatory on October 22, 2006. In H-alpha wing images, we
could see many Ellerman bombs (EBs) in the EFR. Two observation modes, slit
scan and slit fixed, were performed with the vector magnetograph, along with
H-alpha filtergraph. Using H-alpha wing images, we detected 12 EBs during slit
scan observation period and 9 EBs during slit fixed observation period. With
slit scan observation, we found that all the EBs were distributed in the area
where the spatial gradient of vertical field intensity was large, which
indicates the possibility of rapid topological change in magnetic field in the
area of EBs. With slit fixed observation, we found that EBs were distributed in
the areas of undulatory magnetic fields, both in vertical and horizontal
components. This paper is the first to report the undulatory pattern in
horizontal components of magnetic field, which is also evidence for emerging
magnetic flux by Parker instability. These results allow us to confirm the
association between EBs and emerging flux tubes. Three triggering mechanism of
EBs is discussed with respect to emerging flux tubes: 9 out of 21 EBs occurred
at the footpoints of emerging flux tubes, 8 out of 21 EBs occurred at the top
of emerging flux tubes, and 4 out of 21 EBs occurred at unipolar region. Each
case can be explained by magnetic reconnection in the low chromosphere.Comment: 30 pages, 17 figure
Midgut pain due to an intussuscepting terminal ileal lipoma: a case report
<p>Abstract</p> <p>Introduction</p> <p>The occurrence of intussusception in adults is rare. The condition is found in 1 in 1300 abdominal operations and 1 in 100 patients operated for intestinal obstruction. The child to adult ratio is 20:1.</p> <p>Case presentation</p> <p>A 52-year-old Irish Caucasian woman was investigated for a 3-month history of intermittent episodes of colicky midgut pain and associated constipation. Ileocolonoscopy revealed a pedunculated lesion in the terminal ileum prolapsing into the caecum. Computed tomography confirmed a smooth-walled, nonobstructing, low density intramural lesion in the terminal ileum with secondary intussusception. A laparoscopic small bowel resection was performed. Histology revealed a large pedunculated polypoidal mass measuring 4 × 2.5 × 2 cm consistent with a submucosal lipoma. She had complete resolution of her symptoms and remained well at 12-month follow-up.</p> <p>Conclusion</p> <p>This case highlights an unusual cause of incomplete small bowel obstruction successfully treated through interdisciplinary cooperation. Ileal lipomas are not typically amenable to endoscopic removal and require resection. This can be successfully achieved via a laparoscopic approach with early restoration of premorbid functioning.</p
Recognizing Emotions in a Foreign Language
Expressions of basic emotions (joy, sadness, anger, fear, disgust) can be recognized pan-culturally from the face and it is assumed that these emotions can be recognized from a speaker's voice, regardless of an individual's culture or linguistic ability. Here, we compared how monolingual speakers of Argentine Spanish recognize basic emotions from pseudo-utterances ("nonsense speech") produced in their native language and in three foreign languages (English, German, Arabic). Results indicated that vocal expressions of basic emotions could be decoded in each language condition at accuracy levels exceeding chance, although Spanish listeners performed significantly better overall in their native language ("in-group advantage"). Our findings argue that the ability to understand vocally-expressed emotions in speech is partly independent of linguistic ability and involves universal principles, although this ability is also shaped by linguistic and cultural variables
Antiretroviral Strategies to Prevent Mother-to-Child Transmission of HIV: Striking a Balance between Efficacy, Feasibility, and Resistance
Dara Lehman and colleagues discuss a randomized trial that found that adding up to a week of twice-daily zidovudine+lamivudine to single-dose nevirapine reduces the risk of resistance in mothers and infants
Intrinsic Coating Morphology Modulates Acute Drug Transfer in Drug-Coated Balloon Therapy
The hallmark of drug-coated balloon (DCB) therapy for the treatment of peripheral vascular disease is that it allows for reopening of the narrowed lumen and local drug delivery without the need for a permanent indwelling metal implant such as a stent. Current DCB designs rely on transferring drugs such as paclitaxel to the arterial vessel using a variety of biocompatible excipients coated on the balloons. Inherent procedural challenges, along with limited understanding of the interactions between the coating and the artery, interactions between the coating and the balloon as well as site-specific differences, have led to DCB designs with poor drug delivery efficiency. Our study is focused on two clinically significant DCB excipients, urea and shellac, and uses uniaxial mechanical testing, scanning electron microscopy (SEM), and biophysical modeling based on classic Hertz theory to elucidate how coating microstructure governs the transmission of forces at the coating-artery interface. SEM revealed shellac-based coatings to contain spherical-shaped microstructural elements whereas urea-based coatings contained conical-shaped microstructural elements. Our model based on Hertz theory showed that the interactions between these intrinsic coating elements with the arterial wall were fundamentally different, even when the same external force was applied by the balloon on the arterial wall. Using two orthogonal cell-based assays, our study also found differential viability when endothelial cells were exposed to titrated concentrations of urea and shellac, further highlighting the need to maximize coating transfer efficiency in the context of DCB therapies. Our results underscore the significance of the excipient in DCB design and suggest that coating microstructure modulates acute drug transfer during device deployment
Magnetic Flux Cancellation in Ellerman Bombs
Ellerman Bombs (EBs) are often found to be co-spatial with bipolar photospheric magnetic fields. We use Hα
imaging spectroscopy along with Fe I 6302.5 Å spectropolarimetry from the Swedish 1 m Solar Telescope (SST),
combined with data from the Solar Dynamic Observatory, to study EBs and the evolution of the local magnetic
fields at EB locations. EBs are found via an EB detection and tracking algorithm. Using NICOLE inversions of the
spectropolarimetric data, we find that, on average, (3.43 ± 0.49) × 1024 erg of stored magnetic energy disappears
from the bipolar region during EB burning. The inversions also show flux cancellation rates of 1014–1015 Mx s−1
and temperature enhancements of 200 K at the detection footpoints. We investigate the near-simultaneous flaring
of EBs due to co-temporal flux emergence from a sunspot, which shows a decrease in transverse velocity when
interacting with an existing, stationary area of opposite polarity magnetic flux, resulting in the formation of the
EBs. We also show that these EBs can be fueled further by additional, faster moving, negative magnetic flux
regions
Decompressive hemicraniectomy followed by endovascular thrombosuction in a patient with cerebral venous thrombosis
Scientific Assessment and Innovation in Neurosurgical Treatment Strategie
Resequencing Candidate Genes Implicates Rare Variants in Asthma Susceptibility
Common variation in over 100 genes has been implicated in the risk of developing asthma, but the contribution of rare variants to asthma susceptibility remains largely unexplored. We selected nine genes that showed the strongest signatures of weak purifying selection from among 53 candidate asthma-associated genes, and we sequenced the coding exons and flanking noncoding regions in 450 asthmatic cases and 515 nonasthmatic controls. We observed an overall excess of p values <0.05 (p = 0.02), and rare variants in four genes (AGT, DPP10, IKBKAP, and IL12RB1) contributed to asthma susceptibility among African Americans. Rare variants in IL12RB1 were also associated with asthma susceptibility among European Americans, despite the fact that the majority of rare variants in IL12RB1 were specific to either one of the populations. The combined evidence of association with rare noncoding variants in IL12RB1 remained significant (p = 3.7 × 10−4) after correcting for multiple testing. Overall, the contribution of rare variants to asthma susceptibility was predominantly due to noncoding variants in sequences flanking the exons, although nonsynonymous rare variants in DPP10 and in IL12RB1 were associated with asthma in African Americans and European Americans, respectively. This study provides evidence that rare variants contribute to asthma susceptibility. Additional studies are required for testing whether prioritizing genes for resequencing on the basis of signatures of purifying selection is an efficient means of identifying novel rare variants that contribute to complex disease
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