Inert Welding/Brazing Gas Filters and Dryers

The use of hybridized carbon/silicon carbide (C/SiC) fabric to reinforce ceramic matrix composite face sheets and the integration of such face sheets with a foam core creates a sandwich structure capable of withstanding high-heat-flux environments (150 W/sq cm) in which the core provides a temperature drop of 1,000 C between the surface and the back face without cracking or delamination of the structure. The composite face sheet exhibits a bilinear response, which results from the SiC matrix not being cracked on fabrication. In addition, the structure exhibits damage tolerance under impact with projectiles, showing no penetration to the back face sheet. These attributes make the composite ideal for leading-edge structures and control surfaces in aerospace vehicles, as well as for acreage thermal protection systems and in high-temperature, lightweight stiffened structures. By tailoring the coefficient of thermal expansion (CTE) of a carbon fiber containing ceramic matrix composite (CMC) face sheet to match that of a ceramic foam core, the face sheet and the core can be integrally fabricated without any delamination. Carbon and SiC are woven together in the reinforcing fabric. Integral densification of the CMC and the foam core is accomplished with chemical vapor deposition, eliminating the need for bond-line adhesive. This means there is no need to separately fabricate the core and the face sheet, or to bond the two elements together, risking edge delamination during use. Fibers of two or more types are woven together on a loom. The carbon and ceramic fibers are pulled into the same "pick" location during the weaving process. Tow spacing may be varied to accommodate the increased volume of the combined fiber tows while maintaining a target fiber volume fraction in the composite. Foam pore size, strut thickness, and ratio of face sheet to core thickness can be used to tailor thermal and mechanical properties. The anticipated CTE for the hybridized composite is managed by the choice of constituents, varying fiber tow sizes and constituent part ratios. This structural concept provides high strength and stiffness at low density 1.06 g/cu cm in panels tested. Varieties of face sheet constructions are possible, including variations in fiber type and weave geometry. The integrated structures possible with this composite could eliminate the need for non-load-bearing thermal protection systems on top of a structural component. The back sheet can readily be integrated to substructures through the incorporation of ribs. This would eliminate weight and cost for aerospace missions

Viking orbiter system primary mission

An overview of Viking Orbiter (VO) system and subsystem performances during the primary mission (the time period from VO-1 launch on August 20, 1975, through November 15, 1976) is presented. Brief descriptions, key design requirements, pertinent historical information, unique applications or situations, and predicted versus actual performances are included for all VO-1 and VO-2 subsystems, both individually and as an integrated system

From the Ouachitonian : Allyson Oliver

With the unknowns that carried into the summer, junior political science and psychology major Allyson Oliver from Conway wondered if the internship she had in place would carry through. She had the privilege to intern in the public affairs office of Arkansas Attorney General Leslie Rutledge. Fortunately, Oliver’s experience was only delayed a month due to the pandemic and was virtual only a portion of the time

Noncleft Velopharyngeal Insufficiency: Etiology and Need For Surgical Treatment

Objective. Velopharyngeal insufficiency (VPI) occurs frequently in cleft palate patients. VPI also occurs in patients without cleft palate, but little is known about this patient population and this presents a diagnostic dilemma. Our goal is to review the etiology of noncleft VPI and the surgical treatment involved. Design/Patients. A retrospective review of VPI patients from 1990 to 2005. Demographic, genetic, speech, and surgical data were collected. We compared the need for surgery and outcomes data between noncleft and cleft VPI patients using a Student's t-test. Results. We identified 43 patients with noncleft VPI, of which 24 were females and 19 were males. The average age at presentation of noncleft VPI was 9.6 years (range 4.5–21). The average patient age at the time of study was 13.4 years. The etiology of VPI in these noncleft patients was neurologic dysfunction 44%, syndrome-associated 35%, postadenotonsillectomy 7%, and multiple causes 14%. The need for surgical intervention in the noncleft VPI group was 37% (15/43) compared to the cleft palate controls, which was 27% (12/43). There was not a statistical difference between these two groups (P > 0.5). Conclusion. Noncleft VPI often occurs in patients who have underlying neurologic disorders or have syndromes. The rate of speech surgery to address VPI is similar to that of cleft palate patients. We propose that newly diagnosed noncleft VPI patients should undergo a thorough neurologic and genetic evaluation prior to surgery

The Cellular and Molecular Mechanisms of Immuno-Suppression by Human Type 1 Regulatory T Cells

The immuno-regulatory mechanisms of IL-10-producing type 1 regulatory T (Tr1) cells have been widely studied over the years. However, several recent discoveries have shed new light on the cellular and molecular mechanisms that human Tr1 cells use to control immune responses and induce tolerance. In this review we outline the well known and newly discovered regulatory properties of human Tr1 cells and provide an in-depth comparison of the known suppressor mechanisms of Tr1 cells with FOXP3+ Treg. We also highlight the role that Tr1 cells play in promoting and maintaining tolerance in autoimmunity, allergy, and transplantation

Free field calibration of accoustical devices

Call number: LD2668 .R4 1963 G68

Unsupervised fine-tuning data selection for ASR using self-supervised speech models

Self-supervised learning (SSL) has been able to leverage unlabeled data to boost the performance of automatic speech recognition (ASR) models when we have access to only a small amount of transcribed speech data. However, this raises the question of which subset of the available unlabeled data should be selected for transcription. Our work investigates different unsupervised data selection techniques for fine-tuning the HuBERT model under a limited transcription budget. We investigate the impact of speaker diversity, gender bias, and topic diversity on the downstream ASR performance. We also devise two novel techniques for unsupervised data selection: pre-training loss based data selection and the perplexity of byte pair encoded clustered units (PBPE) and we show how these techniques compare to pure data selection. Finally, we analyze the correlations between the inherent characteristics of the selected fine-tuning subsets as how these characteristics correlate with the resultant word error rate. We demonstrate the importance of token diversity, speaker diversity, and topic diversity in achieving the best performance in terms of WER.Computer Science

Characterization and Immunomodulation of Regulatory T cells in Type 1 Diabetes

Type 1 diabetes mellitus (T1D) is a chronic autoimmune disorder characterized by the complete destruction of the insulin-producing pancreatic β cells. The result of β cell loss leads to life-long insulin injections in order to maintain blood glucose levels, and is associated with both micro-vascular and macro-vascular diseases. Disease onset is related to a genetic predisposition, environmental factors, and a cell-mediated immunophenotype. Previous studies using the non-obese diabetic mouse (NOD) suggest that T1D can be prevented by the administration of immunoregulatory proteins that induce/expand both antigen specific and antigen non-specific regulatory cells. The aims of the studies described within are to; i.) test the hypothesis that antigen-specific therapies can prevent diabetes, and ii) to understand the cause(s) of immunoregulatory T cell deficiency in diabetes development. Results from our first study demonstrate that gene therapy with pDNA encoding the β cell protein gluatamic acid decarboxyasle 65 (GAD65) via gene gun significantly prevents diabetes onset in the NOD mouse. Diabetes protection was attributed to the induction of interleukin-4 secreting immunoregulatory T cells. We also discovered that delivery of the same construct via intra-muscularly injection exacerbated diabetes by the preferentially induction of pathogenic type 1 T effector cells. Therefore, our findings show that the route of delivery of pDNA encoding autoantigens is integral in shaping the type of effector cell response. Our second study illustrates that T1D can be regulated by the differential expression of the il2 gene located in the Idd3 locus of the NOD mouse genome. We found that reduced IL-2 production by NOD CD4+ T cells resulted in ~two-fold less induction of FoxP3-expressing regulatory T cells that are critical for regulating autoimmunity. Furthermore, we described a new role for IL-21 whereby IL-21 negatively regulates IL-2 production by CD4+ T cells, thus, perpetuating the inhibition of regulatory T cells. Most importantly, we successfully devised an IL-2 therapy regimen for NOD mice that overcomes the regulatory T cell deficiency which could lead to a new therapeutic approach to prevent and/or treat T1D in humans