Heat transfer characteristics of hypersonic waveriders with an emphasis on the leading edge effects

The heat transfer characteristics in surface radiative equilibrium and the aerodynamic performance of blunted hypersonic waveriders are studied along two constant dynamic pressure trajectories for four different Mach numbers. The inviscid leading edge drag was found to be a small (4 to 8 percent) but not negligible fraction of the inviscid drag of the vehicle. Although the viscous drag at the leading edge can be neglected, the presence of the leading edge will influence the transition pattern of the upper and the lower surfaces and therefore affect the viscous drag of the entire vehicle. For an application similar to the National Aerospace Plane (NASP), the present study demonstrates that the waverider remains a valuable concept at high Mach numbers if a state-of-the-art active cooling device is used along the leading edge. At low Mach number (less than 5), the study shows the surface radiative cooling might be sufficient. In all cases, radiative cooling is sufficient for the upper and lower surfaces of the vehicle if ceramic composites are used as thermal protection

A Study of a Remedial Speech Program in Operation in Four Rural Schools in the State of Utah

Recent speech surveys conducted in Box Elder County showed that approximately 17% of the elementary school children there had speech defects of such seriousness that they needed clinical attention. A remedial speech program was organized and remedial speech training given at four schools in Box Elder County. The purpose of this project was to study this remedial speech program, as it was in operation, in an effort to determine the feasibility and value of such a program

Modeling the Development of Student Assessment

The study reported in this article was an attempt to investigate how teachers evaluate the achievement of their students. The study was based on a dataset created from portfolios containing achievement products such as written assignments and tests and background information for a simulated student in a grade 8 language arts class. The contents of the portfolio were controlled in terms of achievement level of products and the background of the student. As part of an undergraduate teacher education course in classroom assessment, 147 teacher candidates graded the components of an assigned portfolio over a 10-week period and reported a final grade. These scores and grades were the basis for an investigation of the structure underlying the evaluation of achievement by these teacher candidates. The model developed fitted the data well and had resonance with commonsense views on the kinds of factors that could be expected to affect the decisions teachers make about marking student assignments and tests.La recherche décrite dans le présent article constitue une tentative qui visait à étudier la façon dont les enseignants évaluent les réalisations de leurs élèves. L'étude repose sur une base de données créé à partir de dossiers renfermant diverses épreuves telles des travaux écrits et des examens, ainsi que des renseignements complémentaires sur un élève fictif en 8e année dans un cours des arts du langage. Le contenu des dossiers était contrôlé quant aux résultats obtenus aux épreuves et à l'information personnelle sur l'élève. Dans le cadre d'un cours de premier cycle sur l'évaluation en salle de classe, 147 étudiants en pédagogie ont évalué le contenu du dossier qu'on leur a remis. Le projet a duré 10 semaines et a pris fin quand les élèves ont accordé une note finale â l'élève fictif. Ces évaluations et ces notes finales forment la base d'une étude sur la structure sous-jacente à l'évaluation des réalisations telle qu'effectuée par des élèves en pédagogie. Le modèle développé convenait aux données et les résultats reflètent des conclusions de sens commun sur les facteurs qui pourraient influencer les enseignants dans leur évaluation des travaux et des examens

Does Complex Analysis (IRT) Pay Any Dividends in Achievement Testing?

The study was an exploratory investigation of the consequences of using a complex test-anditem analysis approach in a large-scale testing situation that historically has used a conventional approach of simple number-right scoring. In contemplating modifications to a complex, high-stakes testing program that has a long history of successful operation, any change in operations would have to be carefully evaluated to ensure that there is a high probability of improvement through change. So if a change from number-right-type scoring to item response theory (IRT) scoring is under consideration, the question arises: Does the increase in complexity and difficulty associated with the use of IRT pay significant dividends in better achievement estimates? In terms of consequences, it did not make much difference which domain score estimate was selected for use: any estimate gives approximately the same results in terms of mean, standard deviation, error of estimation, and correlation to other sources of estimation of student achievement.Cette recherche a étudié, à titre exploratoire, les conséquences d'employer une analyse complexe du test et des items dans un contexte d'évaluation à grande échelle où on avait l'habitude d'employer une approche traditionnelle selon laquelle le score représente le nombre de bonnes réponses fournies. Pendant le processus d'envisager des modifications à un programme d'évaluation complexe à enjeu considérable qui fonctionne bien depuis plusieurs années, il est important d'évaluer soigneusement tout changement pour se donner les meilleures chances possibles que l'adaptation mène à une amélioration. Ainsi, avant de substituer une évaluation qui reflète le nombre de bonnes réponses fournies par une qui repose sur la théorie de la réponse d'item (TRI), il faut se poser la question suivante: Est-ce que l'accroissement de complexité et de difficulté lié à l'emploi de la TRI mène à de meilleures estimations quant à l'évaluation? Pour les conséquences, il importait peu quel test de rendement on étudiait: toute estimation donne â-peu-près les mêmes résultats en ce qui concerne la moyenne, l'écart type, l'estimation de l'erreur et la corrélation avec les autres sources d'estimation du rendement des élèves

EVALUATION OF THE PROPOSED RULE FOR SETTING CLASS III AND CLASS IV MILK PRICES UNDER FEDERAL MILK MARKETING ORDERS

Marketing,

Effects of morphology on phonons of nanoscopic silver grains

The morphology of nanoscopic Ag grains significantly affects the phonons. Atomistic simulations show that realistic nanograin models display complex vibrational properties. (1) Single-crystalline grains. Nearly-pure torsional and radial phonons appear at low frequencies. For low-energy, faceted models, the breathing mode and acoustic gap (lowest frequency) are about 10% lower than predicted by elasticity theory (ET) for a continuum sphere of the same volume. The sharp edges and the atomic lattice split the ET-acoustic-gap quintet into a doublet and triplet. The surface protrusions associated with nearly spherical, high-energy models produce a smaller acoustic gap and a higher vibrational density of states (DOS) at frequencies \nu<2 THz. (2) Twined icosahedra. In contrast to the single-crystal case, the inherent strain produce a larger acoustic gap, while the core atoms yield a DOS tail extending beyond the highest frequency of single-crystalline grains. (3) Mark's decahedra, in contrast to (1) and (2), do not have a breathing mode; although twined and strained, do not exhibit a high-frequency tail in the DOS. (4) Irregular nanograins. Grain boundaries and surface disorder yield non-degenerate phonon frequencies, and significantly smaller acoustic gap. Only these nanograins exhibit a low-frequency \nu^2 DOS in the interval 1-2 THz.Comment: Version published in Phys. Rev.

Anomalous Excitation Spectra of Frustrated Quantum Antiferromagnets

We use series expansions to study the excitation spectra of spin-1/2 antiferromagnets on anisotropic triangular lattices. For the isotropic triangular lattice model (TLM) the high-energy spectra show several anomalous features that differ strongly from linear spin-wave theory (LSWT). Even in the Neel phase, the deviations from LSWT increase sharply with frustration, leading to roton-like minima at special wavevectors. We argue that these results can be interpreted naturally in a spinon language, and provide an explanation for the previously observed anomalous finite-temperature properties of the TLM. In the coupled-chains limit, quantum renormalizations strongly enhance the one-dimensionality of the spectra, in agreement with experiments on Cs_2CuCl_4.Comment: 4 pages, 5 figures. New Fig. 3 with higher-order series data, paper shortened, references updated, one added (Ref. 28), minor changes otherwise. Published versio

Neuregulin-1 attenuates mortality associated with experimental cerebral malaria.

BackgroundCerebral Malaria (CM) is a diffuse encephalopathy caused by Plasmodium falciparum infection. Despite availability of antimalarial drugs, CM-associated mortality remains high at approximately 30% and a subset of survivors develop neurological and cognitive disabilities. While antimalarials are effective at clearing Plasmodium parasites they do little to protect against CM pathophysiology and parasite-induced brain inflammation that leads to seizures, coma and long-term neurological sequelae in CM patients. Thus, there is urgent need to explore therapeutics that can reduce or prevent CM pathogenesis and associated brain inflammation to improve survival. Neuregulin-1 (NRG-1) is a neurotrophic growth factor shown to protect against brain injury associated with acute ischemic stroke (AIS) and neurotoxin exposure. However, this drug has not been tested against CM-associated brain injury. Since CM-associated brain injuries and AIS share similar pathophysiological features, we hypothesized that NRG-1 will reduce or prevent neuroinflammation and brain damage as well as improve survival in mice with late-stage experimental cerebral malaria (ECM).MethodsWe tested the effects of NRG-1 on ECM-associated brain inflammation and mortality in P. berghei ANKA (PbA)-infected mice and compared to artemether (ARM) treatment; an antimalarial currently used in various combination therapies against malaria.ResultsTreatment with ARM (25 mg/kg/day) effectively cleared parasites and reduced mortality in PbA-infected mice by 82%. Remarkably, NRG-1 therapy (1.25 ng/kg/day) significantly improved survival against ECM by 73% despite increase in parasite burden within NRG-1-treated mice. Additionally, NRG-1 therapy reduced systemic and brain pro-inflammatory factors TNFalpha, IL-6, IL-1alpha and CXCL10 and enhanced anti-inflammatory factors, IL-5 and IL-13 while decreasing leukocyte accumulation in brain microvessels.ConclusionsThis study suggests that NRG-1 attenuates ECM-associated brain inflammation and injuries and may represent a novel supportive therapy for the management of CM

Investigating Teachers' Assessment Practices: Exploratory, Non-Foundationalist, Mixed-Method Research

Audiences for educational research are rarely invited to review the decision-making processes that permeate systematic inquiry. This account of three researchers' efforts to make sense of preservice teachers' assessment practices reveals how methodologically diverse investigations emanated from the context of a single study. The developments, findings, and warrants that characterize this inquiry are presented, as well as arguments why in retrospect this study can be described as exploratory, mixed-method, non-foundationalist research. Consistent with the general themes of pragmatism, the reader is invited to subject the account of novice teachers' assessment practices to intense scrutiny and to judge the success of the researchers' efforts to build at least temporary certainty and primacy for claims about novice teachers' thinking and behavior. The same process can also be used with the suggested consequences for classroom assessment practice, which conclude both this article and the series.Il est rare que Von invite les publics de la recherche pédagogique à revoir le processus de prise de décisions qui imprègne les enquête systématiques. Cet article, qui explique les démarches qu'ont entreprises trois chercheurs pour comprendre les pratiques d'évaluation de stagiaires, révèle comment des enquêtes à méthodologies diverses sont sorties du contexte d'une seule étude. On présente les démarches, les résultats et les vérifications qui caractérisent cette enquête ainsi que des arguments qui affirment pourquoi, a postiori, cette étude peut se définir comme une recherche exploratoire, à méthodes mixtes et non-fondationaliste. Conformément aux thèmes généraux du pragmatisme, on invite le lecteur à examiner minutieusement le compte-rendu des pratiques d'évaluation des enseignants débutants et à juger si les chercheurs ont réussi à établir une certitude et une primauté - même temporaires - quant à leurs conclusions sur le comportement et les réflexions des enseignants débutants. La même approche peut servir pour la pratique d'évaluation en salles de classes. Cet article, ainsi que la série dont elle fait partie, termine par des suggestions quant aux implications des résultats