856 research outputs found
Computation of aircraft component flow fields at transonic Mach numbers using a three-dimensional Navier-Stokes algorithm
A computer analysis was developed for calculating steady (or unsteady) three-dimensional aircraft component flow fields. This algorithm, called ENS3D, can compute the flow field for the following configurations: diffuser duct/thrust nozzle, isolated wing, isolated fuselage, wing/fuselage with or without integrated inlet and exhaust, nacelle/inlet, nacelle (fuselage) afterbody/exhaust jet, complete transport engine installation, and multicomponent configurations using zonal grid generation technique. Solutions can be obtained for subsonic, transonic, or hypersonic freestream speeds. The algorithm can solve either the Euler equations for inviscid flow, the thin shear layer Navier-Stokes equations for viscous flow, or the full Navier-Stokes equations for viscous flow. The flow field solution is determined on a body-fitted computational grid. A fully-implicit alternating direction implicit method is employed for the solution of the finite difference equations. For viscous computations, either a two layer eddy-viscosity turbulence model or the k-epsilon two equation transport model can be used to achieve mathematical closure
Seeking Academic Redemption: The Reconstruction of Learner Identity Among “Underprepared” Adults
A desire to promote learning for personal development and change dominates much of research and practice in adult and higher education. Few studies, however, have attempted to describe how participating learners experience developmental programs, or how they make sense of these programs in the their particular life contexts. In this study, we describe the re-making of a “learner” identity, as narrated by underprepared adults enrolled in a developmentally-oriented community college program
A dominant mutation in β-AMYLASE1 disrupts nighttime control of starch degradation in Arabidopsis leaves
Arabidopsis (Arabidopsis thaliana) leaves possess a mechanism that couples the rate of nighttime starch degradation to
the anticipated time of dawn, thus preventing premature exhaustion of starch and nighttime starvation. To shed light on
the mechanism, we screened a mutagenized population of a starvation reporter line and isolated a mutant that starved
prior to dawn. The mutant had accelerated starch degradation, and the rate was not adjusted to time of dawn. The muta-
tion responsible led to a single amino acid change (S132N) in the starch degradation enzyme BETA-AMYLASE1 (BAM1;
mutant allele named bam1-2D), resulting in a dominant, gain-of-function phenotype. Complete loss of BAM1 (in bam1-1)
did not affect rates of starch degradation, while expression of BAM1(S132N) in bam1-1 recapitulated the accelerated starch
degradation phenotype of bam1-2D. In vitro analysis of recombinant BAM1 and BAM1(S132N) proteins revealed no differ-
ences in kinetic or stability properties, but in leaf extracts, BAM1(S132N) apparently had a higher affinity than BAM1 for
an established binding partner required for normal rates of starch degradation, LIKE SEX FOUR1 (LSF1). Genetic approaches
showed that BAM1(S132N) itself is likely responsible for accelerated starch degradation in bam1-2D and that this activity
requires LSF1. Analysis of plants expressing BAM1 with alanine or aspartate rather than serine at position 132 indicated
that the gain-of-function phenotype is not related to phosphorylation status at this position. Our results strengthen the
view that control of starch degradation in wild-type plants involves dynamic physical interactions of degradative enzymes
and related proteins with a central role for complexes containing LSF1
1,10-Phenanthrolin-1-ium hydrogen (S,S)-tartrate trihydrate and a correction
The title structure, C12H9N2
+·C4H5O6
−·3H2O, shows that one of the protons of d-tartaric acid has been transferred to 1,10-phenanthroline. The d-hydrogen tartrate anions are joined together in a head-to-tail fashion via a short hydrogen bond with donor–acceptor distance of 2.4554 (12) Å, unsymmetrical O—H distances of 1.01 (4) Å and 1.45 (4) Å, and a 174 (4)° O—H—O bond angle. The phenanthrolinium rings are π-stacked with an average separation of 3.58 (11) Å. The structural report corrects a previous report in the literature [Wang et al. (2006 ▶). Acta Cryst. E62, o2508–o2509] of the isostructural l-hydrogen tartrate enantiomer in which the proton transfer and short hydrogen bond were missed
Patterns of Methamphetamine Use During Pregnancy: Results from the Infant Development, Environment, and Lifestyle (IDEAL) Study
The objectives of this study are to characterize methamphetamine (MA) usage patterns during pregnancy, examine whether patterns of MA use are associated with sociodemographic characteristics and prenatal care, and test the hypothesis that persistent or increasing MA use during pregnancy is associated with greater use of other illicit drugs. The sample consisted of 191 MA-using mothers who participated in a large-scale multi-site study of prenatal MA exposure. Patterns of substance use were assessed by maternal self-report via the Substance Use Inventory (SUI), which included detailed information about MA use, including frequency, quantity, and maximum use during each trimester of pregnancy. The study demostrated that on average, the prevalence of MA use decreased over the three trimesters of pregnancy (84.3% vs. 56.0% vs. 42.4%), and decreased frequency was observed among users from the first trimester to the third (3.1 vs. 2.4 vs. 1.5 days/week). Closer examination of the individual patterns revealed that 29.3% of women maintained consistently high frequency, 9.4% increased frequency, 25.7% had a stable low/moderate pattern, and 35.6% decreased their frequency of MA over the course of pregnancy. These four groups did not differ in sociodemographic characteristics; women who decreased their use of MA had significantly more prenatal visits compared to the consistently high-use group, but were the most likely to use alcohol during their pregnancy. In conclusion, this article elucidated the different patterns of MA use in this community sample. Approximately, one third of MA-using mothers could be classified as consistently high users with a profile of use with the greatest risk to themselves and potentially to their infants including high levels of MA use throughout pregnancy and fewer prenatal care visits. Overall, we found that MA use declined across pregnancy; however, a substantial proportion of users had consistently high or increasing MA use, while those who decreased their MA frequency had a higher prevalence of polydrug use. Future research will investigate the association of these patterns with neonatal outcomes
“Re-Culturing” Teacher Education: Inquiry, Evidence, and Action
Currently the press to make policy and practice decisions on the basis of evidence is being coupled with recognition that real change requires shifts in organizational culture. Consequently, there are now many efforts to “re-culture” organizations by making evidence central to decision making. In this article, the authors problematize the notion of a “culture of evidence” in teacher education. Then the article identifies four key aspects involved in efforts to create a culture of evidence at one institution over a five-year period: (1) development of a portfolio of studies about processes and outcomes; (2) recognition that teacher education always poses values questions as well as empirical questions; (3) an exploratory, open-ended approach to evidence construction; and, (4) multiple structures that institutionalize evidence collection and use locally and beyond. The authors suggests that building cultures of evidence has the potential to be transformative in teacher education, but only if challenges related to sustainability, complexity, and balance are addressed
Systemic Infection and Limited Replication of SHIV Vaccine Virus in Brains of Macaques Inoculated Intracerebrally with Infectious Viral DNA
AbstractSHIV deleted in two accessory genes, ΔvpuΔnef SHIVPPC, functioned well as a vaccine against later challenge with highly pathogenic SHIVKU, and it was able to reach the brain after oral inoculation of live virus. In this study, the proviral genome cloned into a plasmid was inoculated as DNA intracerebrally and spread systemically. Few regions of the brain had detectable proviral DNA by real-time PCR. Two measures of virus replication, detection of viral mRNA expression and circular proviral DNA, were negative for those brain regions, with the exception of the infection site in the right parietal lobe, whereas lymphoid tissues were positive by both measures. Histopathological analyses of all the sampled brain and spinal cord regions did not reveal any abnormalities. Despite intracerebral inoculation of the viral DNA, the brain was not targeted for high levels of virus replication
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Factors Influencing Sleep Difficulty and Sleep Quantity in the Citizen Pscientist Psoriatic Cohort.
IntroductionSleep is essential for overall health and well-being, yet more than one-third of adults report inadequate sleep. The prevalence is higher among people with psoriasis, with up to 85.4% of the psoriatic population reporting sleep disruption. Poor sleep among psoriasis patients is particularly concerning because psoriasis is independently associated with many of the same comorbidities as sleep dysfunction, including cardiovascular disease, obesity, and depression. Given the high prevalence and serious consequences of disordered sleep in psoriasis, it is vital to understand the nature of sleep disturbance in this population. This study was designed to help meet this need by using survey data from Citizen Pscientist, an online patient portal developed by the National Psoriasis Foundation.MethodsOur analysis included 3118 participants who identified as having a diagnosis by a physician of psoriasis alone or psoriasis with psoriatic arthritis. Demographic information, psoriasis severity and duration, sleep apnea status, smoking and alcohol consumption, itch timing, and sleep characteristics were included. Two separate multivariate logistic regression models in STATA were used to determine whether the presence of psoriatic arthritis, age, gender, body mass index, comorbid sleep apnea, psoriasis severity, timing of worst itch, smoking status, or high-risk alcohol consumption were associated with sleep difficulty or low sleep quantity, defined by the American Academy of Sleep Medicine as less than 7 h of sleep per night on average.ResultsResults from the multivariate logistic regressions found that sleep difficulty was associated with psoriatic arthritis (OR 2.15, 95% CI [1.79-2.58]), female gender (2.03 [1.67-2.46]), obese body mass index (BMI ≥ 30) (1.25 [1.00-1.56]), sleep apnea (1.41 [1.07-1.86]), psoriasis severity of moderate (1.59 [1.30-1.94]) or severe (2.40 [1.87-3.08]), and smoking (1.60 [1.26-2.02]). Low sleep quantity was associated with obese BMI (1.62 [1.29-2.03]), sleep apnea (1.30 [1.01-1.68]), psoriasis severity of moderate (1.41 [1.16-1.72]) or severe (1.40 [1.11-1.76]), and smoking (1.62 [1.31-2.00]). Sleep difficulty and low sleep quantity were not associated with age, alcohol consumption, or timing of worst itch.ConclusionThese results are potentially meaningful in several aspects. We identify an important distinction between sleep difficulty and sleep quantity in psoriatic disease, whereby having psoriatic arthritis and being female are each associated with sleep difficulty despite no association with low sleep quantity. Furthermore, there is conflicting evidence from prior studies as to whether psoriasis severity is associated with sleep difficulty, but this well-powered, large study revealed a strong, graded relationship between psoriasis severity and both sleep difficulty and low sleep quantity. Overall, our results show that both sleep difficulty and low sleep quantity were associated with multiple factors in this analysis of a large psoriatic cohort. These findings suggest that dermatologists may gather clinically useful information by screening psoriatic patients for trouble sleeping and low sleep quantity to identify potential comorbidities and to more effectively guide disease management
Correlations between in situ denitrification activity and nir-gene abundances in pristine and impacted prairie streams
Denitrification is a process that reduces nitrogen levels in headwaters and other streams. We compared nirS and nirK abundances with the absolute rate of denitrification, the longitudinal coefficient of denitrification (i.e., Kden, which represents optimal denitrification rates at given environmental conditions), and water quality in seven prairie streams to determine if nir-gene abundances explain denitrification activity. Previous work showed that absolute rates of denitrification correlate with nitrate levels; however, no correlation has been found for denitrification efficiency, which we hypothesise might be related to gene abundances. Water-column nitrate and soluble-reactive phosphorus levels significantly correlated with absolute rates of denitrification, but nir-gene abundances did not. However, nirS and nirK abundances significantly correlated with Kden, as well as phosphorus, although no correlation was found between Kden and nitrate. These data confirm that absolute denitrification rates are controlled by nitrate load, but intrinsic denitrification efficiency is linked to nirS and nirK gene abundances
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