6,894 research outputs found
NASA technology utilization program: The small business market
Technology transfer programs were studied to determine how they might be more useful to the small business community. The status, needs, and technology use patterns of small firms are reported. Small business problems and failures are considered. Innovation, capitalization, R and D, and market share problems are discussed. Pocket, captive, and new markets are summarized. Small manufacturers and technology acquisition are discussed, covering external and internal sources, and NASA technology. Small business and the technology utilization program are discussed, covering publications and industrial applications centers. Observations and recommendations include small business market development and contracting, and NASA management technology
Choline Supplementation and Dna Methylation in the Hippocampus and Prefrontal Cortex of Rats Exposed to Alcohol During Development
Fetal Alcohol Spectrum Disorders (FASD) refers to the effects of alcohol exposure during development on individuals. Some of the most frequent deficits seen in children with FASD and in animal models of FASD are spatial memory impairments and impaired executive functioning, which are likely related to alcohol-induced alterations of the hippocampus and medial prefrontal cortex (mPFC), respectively. Choline, a nutrient supplement, has been shown in a rat model to ameliorate some of alcohol‟s teratogenic effects and this effect may be mediated through choline‟ effects on DNA methylation. This study used a rat model of FASD to investigate the underlying mechanisms of alcohol-induced deficits and the impact of choline on these deficits by examining changes in DNA methylation in the PFC and hippocampal areas. Alcohol was given by intragastric intubation to rat pups during the neonatal period (postnatal days 2-10) (ET group), which is equivalent to the third trimester in humans and a period of heightened vulnerability of the brain to alcohol exposure. Control groups included an intubated control group given the intubation procedure without alcohol (IC) and a non-treated control group (NC). Choline or saline was administered subcutaneously to each subject from postnatal day 2 to 20. On postnatal day 21, the brains of the subjects were removed and processed for relative optical density (ROD) of immunohistochemical staining for neuronal-specific enolase (NSE) and global DNA methylation as measured by chemiluminescence using the cpGlobal assay. In the mPFC, choline supplementation led to significant increases in ROD of staining for NSE, regardless of treatment or sex. No differences in NSE staining were found in the CA1 region of the hippocampus. Alcohol exposure caused hypermethylation in the hippocampus and mPFC, which was significantly reduced after choline supplementation. In contrast, control animals showed increases in DNA methylation in both regions after choline supplementation, suggesting that choline supplementation has different effects depending upon the initial state of the brain. This study is the first to show in a rat model of FASD changes in global DNA methylation of the hippocampus CA1 region and mPFC after neonatal alcohol exposure with and without choline supplementation. Molecular mechanisms of alcohol‟s teratogenesis leading to a state of hypermethylation are proposed based on alcohol‟s and choline‟s effects in the folate/choline path to DNA methylation
International student mobility and labour market outcomes: an investigation of the role of level of study, type of mobility, and international prestige hierarchies
Over the last decades, there has been increasing interest in the topic of international student mobility (ISM). However, there is surprisingly little analysis of the ways in which different characteristics and types of short-term ISM or the importance of host education systems and labour markets may affect early career outcomes of formerly mobile graduates. Therefore, in this study we explore, first, the relationship between participation in ISM at the Bachelor and Master level and graduates’ wages and the duration of education-to-work transitions. Second, we investigate variations in ISM’s labour market outcomes according to the type of mobility: study, internships, or combinations of both. Third, we examine the relationship between labour market outcomes of formerly mobile students and the country of destination’s position in higher education international prestige hierarchies and labour market competitiveness. We use the Dutch National Alumni Survey 2015, a representative survey of higher education graduates in the Netherlands, conducted 1.5 years after graduation. Before controlling for selection into ISM, the results suggest the existence of labour market returns to ISM and that the heterogeneity of ISM experiences matters, as labour market outcomes vary according to the level of study, the type of mobility and the positioning of the country of destination in international prestige hierarchies. However, after controlling for selection into ISM through propensity score matching, the differences in early career outcomes between formerly mobile and non-mobile graduates disappear, suggesting that they cannot be causally attributed to their ISM-experience. We explain these results with reference to the characteristics of the Dutch education system and labour market, where restricted possibilities for upward vertical mobility limit returns to ISM in the local labour market
Looking for mangroves: detection of the northernmost West-African mangroves in a non-mangrove dominated landscape using remote sensing
An R- and I-Band Photometric Variability Survey of the Cygnus OB2 Association
We present a catalog of photometrically variable stars discovered within two
21'.3 X 21'.3 fields centered on the Cygnus OB2 association. There have
hitherto been no deep optical variability studies of Cyg OB2 despite it being
replete with early-type massive stars, perhaps due to the high and variable
extinction (up to A_V ~ 20) that permeates much of the region. Here we provide
results of the first variability study with this combination of spatial
coverage (~ 0.5 deg) and photometric depth (R ~ 21 mag). We find 121 stars to
be variable in both R- and I-band, 116 of them newly discovered. Of the 121
variables, we identify 27 eclipsing binaries (EBs) and eclipsing binary
candidates, 20 potential Herbig Ae/Be stars, and 52 pulsating variables.
Confirming both the status and the cluster membership of the Herbig Ae/Be stars
would address the uncertainty regarding the age and star formation history of
Cyg OB2. We match our catalog to known variables and binaries in the region,
2MASS near-IR (NIR) data, and Chandra X-ray observations to find counterparts
to new variables in other wavelengths.Comment: 34 pages, 12 figures, submitted to Ap
Interfacial States in Donor–Acceptor Organic Heterojunctions: Computational Insights into Thiophene-Oligomer/Fullerene Junctions
Donor–acceptor heterojunctions composed of thiophene oligomers and C60 fullerene were investigated with computational methods. Benchmark calculations were performed with time-dependent density functional theory. The effects of varying the density functional, the number of oligomers, the intermolecular distance, the medium polarization, and the chemical functionalization of the monomers were analyzed. The results are presented in terms of diagrams where the electronic states are classified as locally excited states, charge-transfer states, and delocalized states. The effects of each option for computational simulations of realistic heterojunctions employed in photovoltaic devices are evaluated and discussed
Recommended from our members
Synthesis of iso-C-nucleoside analogues from 1-(methyl 2-O-benzyl-4,6-O- benzylidene-3-deoxy-α-D-altropyranosid-3-yl)but-3-yn-2-ones
1-(Methyl 2-O-benzyl-4,6-O-benzylidene-3-deoxy-α-D-altropyranosid-3- yl)but-3-yn-2-one (3a) reacted with 3-amino-1H-1,2,4-triazole and 5-aminopyrazole-4-carboxylic acid derivatives in the presence of base to furnish the triazolo[1,5-a]pyrimidine (5) and the pyrazolo[1,5-a]pyrimidines (8a-d), respectively. Treatment of 1-(methyl 2-O-benzyl-4,6-O-benzylidene-3-deoxy- α-D-altropyranosid-3-yl)-4-phenyl-but-3-yn-2-one (3b) with cyanacetamide, 2-cyano-N-(4-methoxyphenyl)acetamide und N-aryl-3-oxo-butyramides afforded the substituted nicotinonitriles (11a-d). Furthermore, reaction of 3b with 2-benzimidazolyl-acetonitrile yielded the benz[4,5]imidazo[1,2-a]pyridine-4- carbonitrile (13). Deprotection of 8d in two steps afforded the 2-amino-N-benzyl-5-(methyl 3-deoxy-α-D-altropyranosid-3-yl-methyl) pyrazolo[1,5-a]pyrimidine-3-carboxamide (10). Compounds 5 and 11d were treated with AcOH/H2O to furnish the 5-(methyl 2-O-benzyl-3-deoxy-α-D- altropyranosid-3-yl-methyl)[1,2,4]triazolo[1,5-a]pyrimidine (6) and the 3-acetyl-1,2-dihydro-1-(4-methoxyphenyl)-6-(methyl 2-O-benzyl-3-deoxy-α-D- altropyranosid-3-yl-methyl)-4-phenylpyridin-2-one (12), respectively
Sustaining Educational Reforms in Introductory Physics
While it is well known which curricular practices can improve student
performance on measures of conceptual understanding, the sustaining of these
practices and the role of faculty members in implementing these practices are
less well understood. We present a study of the hand-off of Tutorials in
Introductory Physics from initial adopters to other instructors at the
University of Colorado, including traditional faculty not involved in physics
education research. The study examines the impact of implementation of
Tutorials on student conceptual learning across eight first-semester, and seven
second-semester courses, for fifteen faculty over twelve semesters, and
includes roughly 4000 students. It is possible to demonstrate consistently
high, and statistically indistinguishable, student learning gains for different
faculty members; however, such results are not the norm, and appear to rely on
a variety of factors. Student performance varies by faculty background -
faculty involved in, or informed by physics education research, consistently
post higher student learning gains than less-informed faculty. Student
performance in these courses also varies by curricula used - all semesters in
which the research-based Tutorials and Learning Assistants are used have higher
student learning gains than those semesters that rely on non-research based
materials and do not employ Learning Assistants.Comment: 21 pages, 4 figures, and other essential inf
Choline Supplementation and DNA Methylation in the Hippocampus and Prefrontal Cortex of Rats Exposed to Alcohol During Development
BACKGROUND:
Some of the most frequent deficits seen in children with fetal alcohol spectrum disorders (FASD) and in animal models of FASD are spatial memory impairments and impaired executive functioning, which are likely related to alcohol-induced alterations of the hippocampus and prefrontal cortex (PFC), respectively. Choline, a nutrient supplement, has been shown in a rat model to ameliorate some of alcohol\u27s teratogenic effects, and this effect may be mediated through choline\u27s effects on DNA methylation. METHODS:
Alcohol was given by intragastric intubation to rat pups during the neonatal period (postnatal days 2 to 10) (ET group), which is equivalent to the third trimester in humans and a period of heightened vulnerability of the brain to alcohol exposure. Control groups included an intubated control group given the intubation procedure without alcohol (IC) and a nontreated control group (NC). Choline or saline was administered subcutaneously to each subject from postnatal days 2 to 20. On postnatal day 21, the brains of the subjects were removed and assayed for global DNA methylation patterning as measured by chemiluminescence using the cpGlobal assay in both the hippocampal region and PFC. RESULTS:
Alcohol exposure caused hypermethylation in the hippocampus and PFC, which was significantly reduced after choline supplementation. In contrast, control animals showed increases in DNA methylation in both regions after choline supplementation, suggesting that choline supplementation has different effects depending upon the initial state of the brain. CONCLUSIONS:
This study is the first to show changes in global DNA methylation of the hippocampal region and PFC after neonatal alcohol exposure. Choline supplementation impacts global DNA methylation in these 2 brain regions in alcohol-exposed and control animals in a differential manner. The current findings suggest that both alcohol and choline have substantial impact on the epigenome in the PFC and hippocampus, and future studies will be needed to describe which gene families are impacted in such a way that function of the nervous system is changed
- …