Three-dimensional finite element analysis of acoustic instability of solid propellant rocket motors

A three dimensional finite element solution of the acoustic vibration problem in a solid propellant rocket motor is presented. The solution yields the natural circular frequencies of vibration and the corresponding acoustic pressure mode shapes, considering the coupled response of the propellant grain to the acoustic oscillations occurring in the motor cavity. The near incompressibility of the solid propellant is taken into account in the formulation. A relatively simple example problem is solved in order to illustrate the applicability of the analysis and the developed computer code

Determination of wind tunnel constraint effects by a unified pressure signature method. Part 1: Applications to winged configurations

A new, fast, non-iterative version of the "Wall Pressure Signature Method" is described and used to determine blockage and angle-of-attack wind tunnel corrections for highly-powered jet-flap models. The correction method is complemented by the application of tangential blowing at the tunnel floor to suppress flow breakdown there, using feedback from measured floor pressures. This tangential blowing technique was substantiated by subsequent flow investigations using an LV. The basic tests on an unswept, knee-blown, jet flapped wing were supplemented to include the effects of slat-removal, sweep and the addition of unflapped tips. C sub mu values were varied from 0 to 10 free-air C sub l's in excess of 18 were measured in some cases. Application of the new methods yielded corrected data which agreed with corresponding large tunnel "free air" resuls to within the limits of experimental accuracy in almost all cases. A program listing is provided, with sample cases

Determination of wind tunnel constraint effects by a unified pressure signature method. Part 2: Application to jet-in-crossflow

The development of an improved jet-in-crossflow model for estimating wind tunnel blockage and angle-of-attack interference is described. Experiments showed that the simpler existing models fall seriously short of representing far-field flows properly. A new, vortex-source-doublet (VSD) model was therefore developed which employs curved trajectories and experimentally-based singularity strengths. The new model is consistent with existing and new experimental data and it predicts tunnel wall (i.e. far-field) pressures properly. It is implemented as a preprocessor to the wall-pressure-signature-based tunnel interference predictor. The supporting experiments and theoretical studies revealed some new results. Comparative flow field measurements with 1-inch "free-air" and 3-inch impinging jets showed that vortex penetration into the flow, in diameters, was almost unaltered until 'hard' impingement occurred. In modeling impinging cases, a 'plume redirection' term was introduced which is apparently absent in previous models. The effects of this term were found to be very significant

Technology in Education

This comprehensive project examines how overexposure to technology impacts the learning styles of students, and how teaching strategies need to be adapted to meet the changing learning needs of this generation. David Jukes (2010) book, Understanding the Digital Generation (Teaching and Learning in the New Digital Landscape), discusses how students learning styles have evolved and changed over the years due to them being inundated with technology from a young age. This paper will examine Jukes claims, discuss how modern teachers need to adapt their teaching styles to reach students of the Digital Generation, and will offer practical lessons that teachers can use in their classrooms to help promote student engagement in class activities. There second part of the paper is a comprehensive unit on folktales. The unit consists of 11 lessons, and several of the lessons incorporate the technology strategies that have been discussed in the paper. Students will conduct several writing assignments: using word processors, online writing applications, and websites. Students will engage in collaborative group projects. The final assignment in the unit will ask students to compose an original folktale with illustrations. This final assignment will need to be turned in in a professional format. Students will either have their book bound, or it will be turned in in a binder or portfolio. These lessons will also adhere to the New York State Common Core English Language Arts Learning Standards

Experience of sleep disruption in primary Sjögren’s syndrome: A focus group study

Introduction: Primary Sjögren’s syndrome is the third most common systemic autoimmune rheumatic disease, following rheumatoid arthritis and systemic lupus erythematosus, and results in dryness, fatigue, discomfort and sleep disturbances. Sleep is relatively unexplored in primary Sjögren’s syndrome. We investigated the experiences of sleep disturbances from the viewpoint of primary Sjögren’s syndrome patients and their partners and explored the acceptability of cognitive behavioural therapy for insomnia. Method: We used focus groups to collect qualitative data from 10 patients with primary Sjögren’s syndrome and three partners of patients. The data were recorded, transcribed verbatim and analysed using thematic analysis. Results: Five themes emerged from the data: (a) Experience of sleep disturbances; (b) variation and inconsistency in sleep disturbances; (c) the domino effect of primary Sjögren’s syndrome symptoms; (d) strategies to manage sleep; (e) acceptability of evidence-based techniques. Sleep disturbances were problematic for all patients, but specific disturbances varied between participants. These included prolonged sleep onset time and frequent night awakenings and were aggravated by pain and discomfort. Patients deployed a range of strategies to try and self-manage. Cognitive behavioural therapy for insomnia was seen as an acceptable intervention, as long as a rationale for its use is given and it is tailored for primary Sjögren’s syndrome. Conclusion: Primary Sjögren’s syndrome patients described a range of sleep disturbances. Applying tailored, evidence-based sleep therapy interventions may improve sleep, severity of other primary Sjögren’s syndrome symptoms and functional ability

Predicting preferential DNA vector insertion sites: implications for functional genomics and gene therapy

Viral and transposon vectors have been employed in gene therapy as well as functional genomics studies. However, the goals of gene therapy and functional genomics are entirely different; gene therapists hope to avoid altering endogenous gene expression (especially the activation of oncogenes), whereas geneticists do want to alter expression of chromosomal genes. The odds of either outcome depend on a vector's preference to integrate into genes or control regions, and these preferences vary between vectors. Here we discuss the relative strengths of DNA vectors over viral vectors, and review methods to overcome barriers to delivery inherent to DNA vectors. We also review the tendencies of several classes of retroviral and transposon vectors to target DNA sequences, genes, and genetic elements with respect to the balance between insertion preferences and oncogenic selection. Theoretically, knowing the variables that affect integration for various vectors will allow researchers to choose the vector with the most utility for their specific purposes. The three principle benefits from elucidating factors that affect preferences in integration are as follows: in gene therapy, it allows assessment of the overall risks for activating an oncogene or inactivating a tumor suppressor gene that could lead to severe adverse effects years after treatment; in genomic studies, it allows one to discern random from selected integration events; and in gene therapy as well as functional genomics, it facilitates design of vectors that are better targeted to specific sequences, which would be a significant advance in the art of transgenesis

Deconstructing discourses in assessments of child neglect

This article presents the findings of a qualitative study exploring how child neglect is ‘performed’ in social work practice. Informed by Foucauldian and feminist theoretical positions, semi-structured interviews were conducted with ten local authority social workers, eight Children’s Centre professionals in England and eight parents who had received professional intervention due to concerns about child neglect. In addition, ten case files were analysed where child neglect was a substantive concern. This article explores the discourses that were produced in social workers’ assessments of child neglect. In a neo-liberal context in which cuts are being made to childcare services, professionals were preoccupied with the identification and management of neglectful families by risk. Professional debates surrounding contested thresholds into services and categorisation of neglectful families are explored. Judgements of ‘good enough’ mothering as well as bureaucratic and managerial constraints to holistic, analytical and quality assessments are identified. The article also explores the bureaucratic performance of children’s assessed identities through which children become the objects of the assessment rather than active subjects. The article concludes with recommendations for practice and future research

Establishing a Law and Psychiatry Clinic

Psychiatry and law are interdependent to an extent exceeded by few other pairs of professions. As a result, psychiatrists and other mental health professionals (“MHPs”) can wield tremendous power in legal settings. In their Law and Psychiatry Clinic, William Mitchell College of Law and the Department of Psychiatry of the University of Minnesota School of Medicine work at the boundaries of their fields. By adopting a centralized and integrated model for interdisciplinary clinical education, the clinic allows both professions to gain professional and cross-professional competence and understanding. Given the determinative role often played by psychiatry in law, the clinic hopes that its work will lead to more transparency and mindfulness in the use of psychiatric expertise, and therefrom, to an increase in the quality of justice. We begin with a brief description of the development of the clinic, describing its functioning and the particular structure we have adopted for it. We then turn to the educational objectives of the clinic, which leads to our discussion of implementation problems. After offering some evaluative comments about the clinic, we close by discussing the ways in which it might contribute to an increase in justice

Calcium Oxalate Urolithiasis in the Rat: Is it a Model for Human Stone Disease? A Review of Recent Literature

Calcium oxalate stone disease is the most common human urinary stone disease in the Western Hemisphere. To understand different aspects of the disease, calcium oxalate urolithiasis in the rat is used as a model. Spontaneous calcium oxalate urolithiasis is very rare in rats. Thus the disease is experimentally induced and the rats are generally made hyperoxaluric either by administration of excess oxalate, exposure to the toxin ethylene glycol, or various nutritional manipulations. All the experimental models show renal injury associated with crystal deposition. Calcium oxalate crystals are in most cases intraluminal in renal tubules and often attached to the basal lamina of the denuded epithelium. Rat renal papillary tips and fornices appear to be the preferential sites for the deposition of large calcium oxalate calculi. Where urinary supersaturation of calcium oxalate has been studied the crystal forming rat urines are shown to have higher urinary supersaturation of calcium oxalate than their controls. Oxalate metabolism in the rat is nearly identical to that in humans. Thus, in a number of respects, experimental calcium oxalate urolithiasis in the rat is similar to calcium oxalate stone disease in man

Particle Topology, Braids, and Braided Belts

Recent work suggests that topological features of certain quantum gravity theories can be interpreted as particles, matching the known fermions and bosons of the first generation in the Standard Model. This is achieved by identifying topological structures with elements of the framed Artin braid group on three strands, and demonstrating a correspondence between the invariants used to characterise these braids (a braid is a set of non-intersecting curves, that connect one set of $N$ points with another set of $N$ points), and quantities like electric charge, colour charge, and so on. In this paper we show how to manipulate a modified form of framed braids to yield an invariant standard form for sets of isomorphic braids, characterised by a vector of real numbers. This will serve as a basis for more complete discussions of quantum numbers in future work.Comment: 21 pages, 16 figure