Material flow and frictional heating in friction stir welding are investigated using a three-dimensional numerical model. Two mechanical boundary conditions are investigated, including a sticking ...constant velocity and a slipping variable shear stress model. For the constant velocity model, material in contact with the tool is set at a velocity equal to some fraction of the tool rotational speed. The variable shear stress model is formulated such that it degenerates to Coulomb friction under low forces, but as forces at the tool increase, shear stresses at the tool/material boundary are limited according to Tresca friction. The variable shear condition model permits areas of significant slip, while shear stresses at other regions approach the flow stress of the material. The boundary models are compared with experimental data from flow visualization experiments and thermocouple measurements from plasticine welds. Results show that the variable shear model is superior to a sticking condition. With the variable shear model, the peak temperature in the weld compares well with thermocouple measurements. The variable shear model predicts that material simply extrudes around the tool, while the constant velocity model shows a region of material that rotates with the tool. Maximum velocities with the variable shear stress model are only 9% of the rotational speed of the tool and agree well with experimental findings. Additionally, the variable shear model shows a region of diminishing shear stress, velocity, and pressure at the back advancing side of the pin, suggesting formation of an internal void. The limited deformation, low velocities, and suggestion of void formation agree well with flow visualization studies using plasticine under identical operating parameters.
Hypertension is associated with increased levels of circulating cytokines and recent studies have shown that innate immunity contributes to hypertension. The mechanisms which hypertension stimulates ...immune response remain unclear, but may involve formation of neo-antigens that activate the immune system. Toll like receptor 4 (TLR4) is an innate immune receptor that binds a wide spectrum of exogenous (lipopolysaccharide) and endogenous ligands. TLR4 signaling leads to activation of nuclear factor kappa B (NFκB) and transcription of genes involved in inflammatory response. We previously demonstrated that TLR4 blockade reduces blood pressure and the augmented vascular contractility in spontaneously hypertensive rats (SHR). Here we hypothesized that inhibition of TLR4 ameliorates the vascular inflammatory process by a NFκB signaling pathway.
SHR and Wistar rats were treated with anti-TLR4 antibody (1μg/day) or unspecific IgG for 15days (i.p.).
Anti-TLR4 treatment decreased production of reactive oxygen species and expression of IL-6 cytokine in mesenteric resistance arteries from SHR, when compared with IgG-treated SHR. Anti-TLR4 treatment also abolished the increased vascular reactivity to noradrenaline observed in IgG-treated SHR, as described before, and inhibition of NFκB decreased noradrenaline responses only in IgG-treated SHR. Mesenteric arteries from SHR treated with anti-TLR4 displayed decreased expression of MyD88, but not TRIF, key molecules in TLR4 signaling. Phosphorylation of p38 and NF-κB p65 were decreased in arteries from anti-TLR4-treated SHR versus IgG-treated SHR.
Together, these results suggest that TLR4 is a key player in hypertension and vascular inflammatory process by a NFκB signaling pathway.
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Background
Urgent red cell exchange (RBCx) is indicated for many complications of sickle cell disease (SCD), including acute chest syndrome, stroke, and hepatic/splenic sequestration. Many who ...receive RBCx remain hospitalized and develop further complications, including multiple organ dysfunction syndrome (MODS), a leading cause of death in intensive care units. Therapeutic plasma exchange (TPE) has been advocated as an effective treatment of MODS, but its role in SCD compared with RBCx alone is not well studied.
Methods
We identified all ICU encounters from 2013 to 2019 involving RBCx procedures for MODS or SCD crisis that progressed to MODS, a total of 12 encounters. Data regarding hospital length of stay (LOS), survival, number of TPE procedures following RBCx, and procedure characteristics were collected. Surrogate laboratory markers of end‐organ damage and disease severity scores were recorded at the time of admission, post‐RBCx, post‐TPE, and at discharge.
Results
Eight encounters involved RBCx followed by TPE (TPE group) while four involved RBCx alone (RBCx group). The TPE group had a higher SOFA score at ICU admission (9.5 vs. 7.0), greater predicted mortality, and a statistical trend toward higher disease severity scores following RBCx relative to the RBCx group (p = 0.10). The TPE group showed a significantly greater decrease in SOFA score between RBCx and discharge (p = 0.04). No significant difference in mortality or hospital LOS was observed between the groups.
Conclusion
The findings suggest TPE may be considered as an adjunct treatment for patients with acute complications of SCD that progress to MODS, especially in cases where there is no significant improvement following RBCx.
Concept Inventories (CIs) are assessments designed to measure student learning of core concepts. CIs have become well known for their major impact on pedagogical techniques in other sciences, ...especially physics. Presently, there are no widely used, validated CIs for computer science. However, considerable groundwork has been performed in the form of identifying core concepts, analyzing student misconceptions, and developing CI assessment questions. Although much of the work has been focused on CS1 and a CI has been developed for digital logic, some preliminary work on CIs is underway for other courses. This literature review examines CI work in other STEM disciplines, discusses the preliminary development of CIs in computer science, and outlines related research in computer science education that contributes to CI development.
Three-dimensional silicon integration Knickerbocker, J U; Andry, P S; Dang, B ...
IBM journal of research and development,
11/2008, Letnik:
52, Številka:
6
Journal Article
Recenzirano
Three-dimensional (3D) silicon integration of active devices with through-silicon vias (TSVs), thinned silicon, and silicon-to-silicon fine-pitch interconnections offers many product benefits. ...Advantages of these emerging 3D silicon integration technologies can include the following: power efficiency, performance enhancements, significant product miniaturization, cost reduction, and modular design for improved time to market. IBM research activities are aimed at providing design rules, structures, and processes that make 3D technology manufacturable for chips used in actual products on the basis of data from test-vehicle (i.e., prototype) design, fabrication, and characterization demonstrations. Three-dimensional integration can be applied to a wide range of interconnection densities (<10/cm^sup 2^ to 10^sup 8^/cm^sup 2^), requiring new architectures for product optimization and multiple options for fabrication. Demonstration test structures, which are designed, fabricated, and characterized, are used to generate experimental data, establish models and design guidelines, and help define processes for future product consideration. This paper 1) reviews technology integration from a historical perspective, 2) describes industry-wide progress in 3D technology with examples of TSV and silicon-silicon interconnection advancement over the last 10 years, 3) highlights 3D technology from IBM, including demonstration test vehicles used to develop ground rules, collect data, and evaluate reliability, and 4) provides examples of 3D emerging industry product applications that could create marketable systems. PUBLICATION ABSTRACT
Rapid-onset dystonia-parkinsonism (RDP) (also known as DYT12) is characterized by the abrupt onset of dystonia and parkinsonism and is caused by mutations in the ATP1A3 gene. We obtained clinical ...data and sequenced the ATP1A3 gene in 49 subjects from 21 families referred with 'possible' RDP, and performed a genotype-phenotype analysis. Of the new families referred for study only 3 of 14 families (21%) demonstrated a mutation in the ATP1A3 gene, but no new mutations were identified beyond our earlier report of 6. Adding these to previously reported families, we found mutations in 36 individuals from 10 families including 4 de novo mutations and excluded mutations in 13 individuals from 11 families. The phenotype in mutation positive patients included abrupt onset of dystonia with features of parkinsonism, a rostrocaudal gradient, and prominent bulbar findings. Other features found in some mutation carriers included common reports of triggers, minimal or no tremor at onset, occasional mild limb dystonia before the primary onset, lack of response to dopaminergic medications, rare abrupt worsening of symptoms later in life, stabilization of symptoms within a month and minimal improvement overall. In comparing ATP1A3 mutation positive and negative patients, we found that tremor at onset of symptoms, a reversed rostrocaudal gradient, and significant limb pain exclude a diagnosis of RDP. A positive family history is not required. Genetic testing for the ATP1A3 gene is recommended when abrupt onset, rostrocaudal gradient and prominent bulbar findings are present.
Background
Previous studies have identified hypoalbuminemia as a risk factor for negative outcome in dogs with chronic enteropathy (CE), but it has not been determined whether histopathology differs ...between CE dogs with and without hypoalbuminemia.
Objective
To compare histopathologic findings in dogs with biopsy‐diagnosed inflammatory CE with and without hypoalbuminemia.
Animals
83 dogs that had intestinal biopsy performed between January 2010–July 2015. Dogs had signs compatible with CE of at least 3‐weeks' duration and no evidence of clinically relevant extra‐gastrointestinal (GI) disease or potential non‐GI causes of hypoalbuminemia. Dogs had primary diagnosis of inflammatory enteritis based on histopathology.
Methods
Dogs were grouped into CE with normoalbuminemia (CEN; serum albumin concentration ≥3.0 g/dL, N = 46) or chronic enteropathy with hypoalbuminemia (CEH; serum albumin concentration <3.0 g/dL, N = 37). A pathologist (SLP) blinded to the groups reviewed biopsy samples and applied the World Small Animal Veterinary Association scoring system to all samples.
Results
Intestinal biopsy samples from dogs in the CEH group were significantly more likely to display villous stunting, epithelial injury, crypt distension, and lacteal dilatation, and were more likely to have intraepithelial lymphocytes and lamina propria neutrophils than biopsy samples from dogs in the CEN group. Additionally, higher scores for each of the above listed histopathologic criteria were associated with a lower serum albumin concentration.
Conclusions and Clinical Importance
Histopathologic features of chronic inflammatory enteropathy differ between dogs that are hypo‐ versus normoalbuminemic. Additional work is needed to elucidate the clinical relevance of these differences.
Asset, activity and income diversification lie at the heart of livelihood strategies in rural Africa. This paper introduces a special issue on the topic “Income Diversification and Livelihoods in ...Rural Africa: Cause and Consequence of Change.” We concentrate on core conceptual issues that bedevil the literature on rural income diversification and the policy implications of the empirical evidence presented in this special issue.
Persons discharged from inpatient psychiatric services are at greatly elevated risk of harming themselves or inflicting violence on others, but no studies have reported gender-specific absolute risks ...for these two outcomes across the spectrum of psychiatric diagnoses. We aimed to estimate absolute risks for self-harm and interpersonal violence post-discharge according to gender and diagnostic category.
Danish national registry data were utilized to investigate 62,922 discharged inpatients, born 1967-2000. An age and gender matched cohort study was conducted to examine risks for self-harm and interpersonal violence at 1 year and at 10 years post-discharge. Absolute risks were estimated as cumulative incidence percentage values.
Patients diagnosed with substance misuse disorders were at especially elevated risk, with the absolute risks for either self-harm or interpersonal violence being 15.6% (95% CI 14.9, 16.3%) of males and 16.8% (15.6, 18.1%) of females at 1 year post-discharge, rising to 45.7% (44.5, 46.8%) and 39.0% (37.1, 40.8%), respectively, within 10 years. Diagnoses of personality disorders and early onset behavioral and emotional disorders were also associated with particularly high absolute risks, whilst risks linked with schizophrenia and related disorders, mood disorders, and anxiety/somatoform disorders, were considerably lower.
Patients diagnosed with substance misuse disorders, personality disorders and early onset behavioral and emotional disorders are at especially high risk for internally and externally directed violence. It is crucial, however, that these already marginalized individuals are not further stigmatized. Enhanced care at discharge and during the challenging transition back to life in the community is needed.
Background: Histopathology is the gold standard for the diagnosis of pancreatic disease. Laparoscopy offers a minimally invasive route by which to obtain pancreatic biopsies.
Hypothesis: Laparoscopy ...is a safe and effective technique for evaluating the pancreas in small animal patients.
Animals: Medical records of 18 dogs and 13 cats examined between 1999 and 2007 that underwent laparoscopy during which observation or biopsy of the pancreas was recorded.
Methods: The database for the Laparoscopy Laboratory at Colorado State University was searched for records that contained “pancreatitis,”“pancreas,” or “pancreatic.” The presenting complaints, imaging studies, and histopathologic findings of animals were recorded. All hospital admissions were searched for animals with the same presenting complaints and of those it was determined which animals had exploratory surgery and their pancreas biopsied.
Results: Thirteen cats and 18 dogs underwent laparoscopy for presumptive pancreatic disease or had the appearance of the pancreas described, pancreatic biopsies obtained, or both. In 14 animals a laparoscopic biopsy of the pancreas resulted in a histopathologic diagnosis when the sonographic findings or the gross assessment failed to do so. In 35% of the animals a biopsy of the pancreas was not obtained despite findings consistent with pancreatic disease. Those animals examined for vomiting or anorexia were significantly more likely to have a biopsy of the pancreas obtained through laparoscopy versus surgery (P < .0001).
Conclusions and Clinical Importance: Laparoscopy and pancreatic biopsy is useful for evaluation of pancreatic disease.
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