258 research outputs found
Three dimensional multi-pass repair weld simulations
Full 3-dimensional (3-D) simulation of multi-pass weld repairs is now feasible and practical given the development of improved analysis tools and significantly greater computer power. This paper presents residual stress results from 3-D finite element (FE) analyses simulating a long (arc length of 62°) and a short (arc length of 20°) repair to a girth weld in a 19.6 mm thick, 432 mm outer diameter cylindrical test component. Sensitivity studies are used to illustrate the importance of weld bead inter-pass temperature assumptions and to show where model symmetry can be used to reduce the analysis size.
The predicted residual stress results are compared with measured axial, hoop and radial through-wall profiles in the heat affected zone of the test component repairs. A good overall agreement is achieved between neutron diffraction and deep hole drilling measurements and the prediction at the mid-length position of the short repair. These results demonstrate that a coarse 3-D FE model, using a ‘block-dumped’ weld bead deposition approach (rather than progressively depositing weld metal), can accurately capture the important components of a short repair weld residual stress field. However, comparisons of measured with predicted residual stress at mid-length and stop-end positions in the long repair are less satisfactory implying some shortcomings in the FE modelling approach that warrant further investigation
First-in-Human Segmental Esophageal Reconstruction Using a Bioengineered Mesenchymal Stromal Cell-Seeded Implant
INTRODUCTION: Resection and reconstruction of the esophagus remains fraught with morbidity and mortality. Recently, data from a porcine reconstruction model revealed that segmental esophageal reconstruction using an autologous mesenchymal stromal cell-seeded polyurethane graft (Cellspan esophageal implant [CEI]) can facilitate esophageal regrowth and regeneration. To this end, a patient requiring a full circumferential esophageal segmental reconstruction after a complex multiorgan tumor resection was approved for an investigational treatment under the Food and Drug Administration Expanded Access Use (Investigational New Drug 17402).
METHODS: Autologous adipose-derived mesenchymal stromal cells (Ad-MSCs) were isolated from the Emergency Investigational New Drug patient approximately 4 weeks before surgery from an adipose tissue biopsy specimen. The Ad-MSCs were grown and expanded under current Good Manufacturing Practice manufacturing conditions. The cells were then seeded onto a polyurethane fiber mesh scaffold (Cellspan scaffold) and cultured in a custom bioreactor to manufacture the final CEI graft. The cell-seeded scaffold was then shipped to the surgical site for surgical implantation. After removal of a tumor mass and a full circumferential 4 cm segment of the esophagus that was invaded by the tumor, the CEI was implanted by suturing the tubular CEI graft to both ends of the remaining native esophagus using end-to-end anastomosis.
RESULTS: In this case report, we found that a clinical-grade, tissue-engineered esophageal graft can be used for segmental esophageal reconstruction in a human patient. This report reveals that the graft supports regeneration of the esophageal conduit. Histologic analysis of the tissue postmortem, 7.5 months after the implantation procedure, revealed complete luminal epithelialization and partial esophageal tissue regeneration.
CONCLUSIONS: Autologous Ad-MSC seeded onto a tubular CEI tissue-engineered graft stimulates tissue regeneration following implantation after a full circumferential esophageal resection
Collaborative inhibition and semantic recall:improving collaboration through computer-mediated communication
Two experiments investigated the recall of nominal and collaborating groups to test the hypotheses that (a) semantic memory, as well as episodic memory, is disrupted by collaborative recall and (b) both episodic and semantic recall will be greater in groups collaborating via computer mediated communication (CMC) than groups collaborating face-to-face. Experiment 1 investigated different collaborative constellations (nominal, face-to-face and parallel CMC) in a series of episodic and semantic word recall tasks. In Experiment 2, collaborative groups (nominal, face-to-face, parallel CMC and cyclic CMC) completed a Scrabble task in which they were required to generate words from a set of 12 letters. Both experiments demonstrated that collaborative inhibition was present in semantic recall. Parallel CMC improved recall by comparison to face-to-face collaboration in both experiments, whereas cyclic CMC did not. The underlying causes of collaborative inhibitory effects and the potential for reducing them with CMC are discussed
Age-dependent white matter disruptions after military traumatic brain injury: Multivariate analysis results from ENIGMA brain injury
Mild Traumatic brain injury (mTBI) is a signature wound in military personnel, and repetitive mTBI has been linked to age-related neurogenerative disorders that affect white matter (WM) in the brain. However, findings of injury to specific WM tracts have been variable and inconsistent. This may be due to the heterogeneity of mechanisms, etiology, and comorbid disorders related to mTBI. Non-negative matrix factorization (NMF) is a data-driven approach that detects covarying patterns (components) within high-dimensional data. We applied NMF to diffusion imaging data from military Veterans with and without a self-reported TBI history. NMF identified 12 independent components derived from fractional anisotropy (FA) in a large dataset (n = 1,475) gathered through the ENIGMA (Enhancing Neuroimaging Genetics through Meta-Analysis) Military Brain Injury working group. Regressions were used to examine TBI- and mTBI-related associations in NMF-derived components while adjusting for age, sex, post-traumatic stress disorder, depression, and data acquisition site/scanner. We found significantly stronger age-dependent effects of lower FA in Veterans with TBI than Veterans without in four components (q \u3c 0.05), which are spatially unconstrained by traditionally defined WM tracts. One component, occupying the most peripheral location, exhibited significantly stronger age-dependent differences in Veterans with mTBI. We found NMF to be powerful and effective in detecting covarying patterns of FA associated with mTBI by applying standard parametric regression modeling. Our results highlight patterns of WM alteration that are differentially affected by TBI and mTBI in younger compared to older military Veterans
Grazing management in saltmarsh ecosystems drives invertebrate diversity, abundance and functional group structure
1. Saltmarsh conservation management often involves livestock grazing
to maximise plant diversity and provide suitable breeding habitat for over-wintering
coastal birds. The effect of grazing on invertebrates is rarely quantified, but results
from limited studies of terrestrial and coastal grasslands demonstrate greater abundance
and species richness in un-grazed grassland.
2. The impact of short sward (<8 cm) cattle grazing on the ground dwelling invertebrate
community was assessed on an English inter-tidal upper salt marsh using pitfall
traps. Abundance, species richness, functional group structure, abundance of
coastal specialists, environmental factors that influence invertebrate habitat choice
and food web composition were compared for grazed and un-grazed marsh.
3. In total, 90 000 invertebrates were sampled. Predatory, zoophagus and detritivorous
Coleoptera were significantly more abundant on the un-grazed marsh. In contrast,
predatory Hemiptera and Araneae were significantly more abundant on the
grazed marsh. Sheet weaver spiders were significantly more abundant on the grazed
marsh, foliage running hunters and space web builders more abundant on the ungrazed
marsh. Most inter-tidal coastal specialist species exhibited clear habitat preference
for the grazed marsh. Total species richness was not significantly different
between grazing treatments.
4. Linear direct gradient analysis showed that two environmental variables influenced
by grazing intensity, soil temperature and vegetation height, significantly
explained the composition of invertebrate functional groups. Larger bodied invertebrates
dominated the un-grazed food web.
5. We conclude that both short sward cattle grazed and un-grazed saltmarsh habitat
should be maintained to maximise invertebrate abundance and diversity and provide
suitable habitat for coastal specialists
Omics approaches to identify potential biomarkers of inflammatory diseases in the focal adhesion complex
Inflammatory diseases such as inflammatory bowel disease require recurrent invasive tests, including blood tests, radiology and endoscopic evaluation for diagnosis, assessment of disease activity and to determine optimal therapeutic strategies. ‘Bedside’ simple biomarkers could be used in all phases of patient management to avoid unnecessary investigation and guide further management. The focal adhesion complex has been implicated in the pathogenesis of multiple inflammatory diseases including inflammatory bowel disease, rheumatoid arthritis and multiple sclerosis. Utilising ‘omics approaches has proven to be an efficient method to identify biomarkers from within the focal adhesion complex in the field of cancer medicine and predictive biomarkers are paving the way for the success of precision medicine for cancer patients, but inflammatory diseases have lagged behind in this respect. This review explores the current status of biomarker prediction for inflammatory diseases from within the focal adhesion complex using ‘omics techniques and looks forward to future potential avenues for biomarker identification
Modulated expression of WFDC1 during carcinogenesis and cellular senescence
Fibroblasts located adjacent to the tumor [cancer-associated fibroblasts (CAFs)] that constitute a large proportion of the cancer-associated stroma facilitate the transformation process. In this study, we compared the biological behavior of CAFs that were isolated from a prostate tumor to their normal-associated fibroblast (NAF) counterparts. CAFs formed more colonies when seeded at low cell density, exhibited a higher proliferation rate and were less prone to contact inhibition. In contrast to the general notion that high levels of α-smooth muscle actin serve as a marker for CAFs, we found that prostate CAFs express it at a lower level compared with prostate NAFs. Microarray analysis revealed a set of 161 genes that were altered in CAFs compared with NAFs. We focused on whey acidic protein four-disulfide core domain 1 (WFDC1), a known secreted protease inhibitor, and found it to be downregulated in the CAFs. WFDC1 expression was also dramatically downregulated in highly prolific mesenchymal cells and in various cancers including fibrosarcomas and in tumors of the lung, bladder and brain. Overexpression of WFDC1 inhibited the growth rate of the fibrosarcoma HT1080 cell line. Furthermore, WFDC1 level was upregulated in senescent fibroblasts. Taken together, our data suggest an important role for WFDC1 in inhibiting proliferation of both tumors and senescent cells. Finally, we suggest that the downregulation of WFDC1 might serve as a biomarker for cellular transformation
Sport, genetics and the `natural athlete': The resurgence of racial science
This article explores the ethical implications of recent discussions that naturalize the relationship between race, the body and sport within the frame of genetic science. Many suggestions of a racially distributed genetic basis for athletic ability and performance are strategically posited as a resounding critique of the `politically correct' meta-narratives of established sociological and anthropological forms of explanation that emphasize the social and cultural construction of race. I argue that this use of genetic science in order to describe and explain common-sense impressions of racial physiology and sporting ability is founded on erroneous premises of objectivity and disinterest, and inflates the analytical efficacy of scientific truth claims. I suggest that assertions of a value-free science of racial athletic ability reify race as inherited permanent biological characteristics that produce social hierarchies and are more characteristic of a longer history of `racial science'
Efficacy of exposure versus cognitive therapy in anxiety disorders: systematic review and meta-analysis
<p>Abstract</p> <p>Background</p> <p>There is growing evidence of the effectiveness of Cognitive Behavioural Therapy (CBT) for a wide range of psychological disorders. There is a continued controversy about whether challenging maladaptive thoughts rather than use of behavioural interventions alone is associated with the greatest efficacy. However little is known about the relative efficacy of various components of CBT. This review aims to compare the relative efficacy of Cognitive Therapy (CT) versus Exposure (E) for a range of anxiety disorders using the most clinically relevant outcome measures and estimating the summary relative efficacy by combining the studies in a meta-analysis.</p> <p>Methods</p> <p>Psych INFO, MEDLINE and EMBASE were searched from the first available year to May 2010. All randomised controlled studies comparing the efficacy of exposure with cognitive therapy were included. Odds ratios (OR) or standardised means' differences (Hedges' g) for the most clinically relevant primary outcomes were calculated. Outcomes of the studies were grouped according to specific disorders and were combined in meta-analyses exploring short-term and long-term outcomes.</p> <p>Results</p> <p>20 Randomised Controlled Trials with (n = 1,308) directly comparing the efficacy of CT and E in anxiety disorders were included in the meta-analysis. No statistically significant difference in the relative efficacy of CT and E was revealed in Post Traumatic Stress Disorder (PTSD), in Obsessive Compulsive Disorder (OCD) and in Panic Disorder (PD). There was a statistically significant difference favouring CT versus E in Social Phobia both in the short-term (Z = 3.72, p = 0.0002) and the long-term (Z = 3.28, p = 0.001) outcomes.</p> <p>Conclusions</p> <p>On the basis of extant literature, there appears to be no evidence of differential efficacy between cognitive therapy and exposure in PD, PTSD and OCD and strong evidence of superior efficacy of cognitive therapy in social phobia</p
- …