A design method for entrance sections of transonic wind tunnels with rectangular cross sections

A mathematical technique developed to design entrance sections for transonic or high-speed subsonic wind tunnels with rectangular cross sections is discribed. The transition from a circular cross-section setting chamber to a rectangular test section is accomplished smoothly so as not to introduce secondary flows (vortices or boundary-layer separation) into a uniform test stream. The results of static-pressure measurements in the transition region and of static and total-pressure surveys in the test section of a pilot model for a new facility at the Ames Research Center are presented

Efficient markets: land and slave prices in Henrico County, Virginia, 1782-1863

Asset market efficiency fosters rational decisions on allocating resources, both individually and socially, and thus helps determine individuals' wealth accumulation and nations' economic growth. To date, however, there are little systematic data available for, and even less analysis of, US capital markets during the late eighteenth and mid-nineteenth centuries, a period of great transformation and growth. This paper is a preliminary exploration of market efficiency in two early US asset markets, looking at prices of land and slaves in Henrico County, Virginia, from the 1780s to the 1860s. Our hypothesis tests on both the price of and returns to Henrico County land and slaves provide evidence that land and slave markets in late eighteenth and early nineteenth century US were weak-form efficient, suggesting that available information was quickly and fully incorporated into prices in these early North American asset markets.efficient markets, random walk, Dickey-Fuller, KPSS test, slave prices, land prices

Simulation of turbulent transonic separated flow over an airfoil

A code developed for simulating high Reynolds number transonic flow fields of arbitrary configuration is described. This code, in conjunction with laboratory experiments, is used to devise and test turbulence transport models which may be suitable in the prediction of such flow fields, with particular emphasis on regions of flow separation. The solutions describe the flow field, including both the shock-induced and trailing-edge separation regions, in sufficient detail to provide the profile and friction drag

An experimental and computational investigation of the flow field about a transonic airfoil in supercritical flow with turbulent boundary-layer separation

A combined experimental and computational research program is described for testing and guiding turbulence modeling within regions of separation induced by shock waves incident in turbulent boundary layers. Specifically, studies are made of the separated flow the rear portion of an 18%-thick circular-arc airfoil at zero angle of attack in high Reynolds number supercritical flow. The measurements include distributions of surface static pressure and local skin friction. The instruments employed include highfrequency response pressure cells and a large array of surface hot-wire skin-friction gages. Computations at the experimental flow conditions are made using time-dependent solutions of ensemble-averaged Navier-Stokes equations, plus additional equations for the turbulence modeling

Relationship-Based Infant Care as a Framework for Authentic Practice: How Eun Mi Rediscovered her Teaching Soul

In this paper, we explore the complex nature of preparing diverse professionals for authentic, relationship-based care for infants and toddlers in child care. Looking through the eyes of one student caregiver, we travel with her through a semester-long course introducing her to infant care as an integral part of early childhood teacher preparation. We draw on her descriptions of her weekly experiences in an infant room focusing on a key child, her formal reflections in written assignments, and her responses to a series of interview questions once the course was completed to construct a theory of authentic practice through relationship-based teaching and caring. Bringing together the theoretical frames of funds of identity and use of self in authentic practice, we explore the ways that teacher identity unfolds and potentially changes through practice, feedback, and reflective engagement. Our analysis reveals the power of relationship-based learning as a framework for educating diverse teachers for quality infant care

Unraveling Universalist Perspectives on Teaching and Caring for Infants and Toddlers: Finding Authenticity in Diverse Funds of Knowledge

Although child-rearing beliefs and practices vary widely across cultures, a dominant discourse on how to teach and care for young children undergirds most early childhood teacher education programs. In this qualitative multicase study, the authors explored the ways that immigrant preservice teachers negotiated their emerging teacher identities across discontinuities between their own funds of knowledge and the theory and practice presented in their infant and toddler practicum course. Using a funds of identity framework, the authors drew on multiple data sources to examine how three immigrant students questioned, complicated, expanded on, connected, and/or denied their funds of knowledge as they redefined their professional sense of themselves as teachers. Findings indicate that creating a hybrid space within a teacher education practicum course allowed immigrant preservice teachers to comfortably bring their funds of knowledge, critically reflect on their own practice, and authentically develop their emerging teacher identities. Implications are discussed, focusing on the importance of understanding the impact and contribution of teachers’ personal knowledge, the fluidity of immigrant students’ thinking within a hybrid learning space, and the need for teacher education programs that openly invite and honor immigrant preservice teachers’ diverse funds of knowledge to help them find authenticity in teaching and learning

GENETIC CONTROL OF THE ANTIBODY RESPONSE IN INBRED MICE : TRANSFER OF RESPONSE BY SPLEEN CELLS AND LINKAGE TO THE MAJOR HISTOCOMPATIBILITY (H-2) LOCUS

The transfer of spleen cells from (C3H x C57Bl/6) F1 mice, capable of responding to (T,G)-A--L, into irradiated C3H parental recipients, normally incapable of responding to (T,G)-A--L, transfers the ability to make either a primary or secondary immune response to this synthetic polypeptide antigen. This localizes the genetic control of the ability to respond to the spleen cell population and indicates that the genetic control is exerted upon a process directly related to antibody formation. Studies with congenic strains of mice and linkage studies in segregating backcross populations show that the ability to respond to (T,G)-A--L and (H,G)-A--L is linked to the H-2 locus and can thus be localized to the IXth mouse linkage group. Note Added in Proof: Of the three possible recombinant animals noted in Tables IV and V, two were infertile. The third animal was not a recombinant, since progeny testing and reimmunization showed that this animal was an H-22/H-2k heterozygote capable of responding well to (T,G)-A--L

When good news leads to bad choices

Pigeons and other animals sometimes deviate from optimal choice behavior when given informative signals for delayed outcomes. For example, when pigeons are given a choice between an alternative that always leads to food after a delay and an alternative that leads to food only half of the time after a delay, preference changes dramatically depending on whether the stimuli during the delays are correlated with (signal) the outcomes or not. With signaled outcomes, pigeons show a much greater preference for the suboptimal alternative than with unsignaled outcomes. Key variables and research findings related to this phenomenon are reviewed, including the effects of durations of the choice and delay periods, probability of reinforcement, and gaps in the signal. We interpret the available evidence as reflecting a preference induced by signals for good news in a context of uncertainty. Other explanations are briefly summarized and compared

The Influence of Quadrature Errors on Isogeometric Mortar Methods

Mortar methods have recently been shown to be well suited for isogeometric analysis. We review the recent mathematical analysis and then investigate the variational crime introduced by quadrature formulas for the coupling integrals. Motivated by finite element observations, we consider a quadrature rule purely based on the slave mesh as well as a method using quadrature rules based on the slave mesh and on the master mesh, resulting in a non-symmetric saddle point problem. While in the first case reduced convergence rates can be observed, in the second case the influence of the variational crime is less significant

Zinc stress induces copper depletion in Acinetobacter baumannii

Background: The first row transition metal ions zinc and copper are essential to the survival of many organisms, although in excess these ions are associated with significant toxicity. Here, we examined the impact of zinc and copper stress on Acinetobacter baumannii, a common opportunistic pathogen. Results: We show that extracellular zinc stress induces a copper-specific depletion phenotype in A. baumannii ATCC 17978. Supplementation with copper not only fails to rescue this phenotype, but further exacerbates the copper depletion. Extensive analysis of the A. baumannii ATCC 17978 genome identified 13 putative zinc/copper resistance efflux pumps. Transcriptional analyses show that four of these transporters are responsive to zinc stress, five to copper stress and seven to the combination of zinc and copper stress, thereby revealing a likely foundation for the zinc-induced copper starvation in A. baumannii. In addition, we show that zinc and copper play crucial roles in management of oxidative stress and the membrane composition of A. baumannii. Further, we reveal that zinc and copper play distinct roles in macrophage-mediated killing of this pathogen. Conclusions: Collectively, this study supports the targeting of metal ion homeostatic mechanisms as an effective antimicrobial strategy against multi-drug resistant bacterial pathogens.Karl A. Hassan, Victoria G. Pederick, Liam D. H. Elbourne, Ian T. Paulsen, James C. Paton, Christopher A. McDevitt and Bart A. Eijkelkam