460 research outputs found
The Hedonic Experience of Enjoyment and Its Relationship to Informal Learning: A Study of Museum Websites
Online hedonic experiences are increasingly of interest in both research and practice. In particular, it has been proposed that ‘traditional usability approaches are too limited and must be extended to encompass enjoyment’ (Blythe and Wright 2003, p.xvi). The aim of this study was to investigate the relationships among: (i) website design features; (ii) user’s experience of enjoyment; and (iii) informal learning such as that occurring with a museum website. A cross-over experimental design was employed with web pages from the National Palace Museum, Taiwan. Results indicated that, as expected, a multimedia game-based ‘lesson’ led to both more enjoyment and more learning than a text-based ‘lesson’. With text-based pages more enjoyment also meant more learning. The situation was complicated, however, with the game-based pages, as results were not in the expected direction. The study points to the need for more research in this complex area
Observations on the safety of Cremaphor® ELP in rats following intravenous administration
Cremaphor® ELP (CrELP) has been used to emulsify and solubilize water-insoluble substances in the pharmaceutical industry for oral, topical and parenteral preparations, but its safety profile via the intravenous route is yet to be established. In the current report, a wide range of CrELP concentrations associated with different viscosities were formulated and administered intravenously to rats in order to evaluate the acute safety and tolerability. Doses of CrELP were administered once in a fixed volume (5 ml/kg) and
concentrations tested in mg/kg included 7.5, 75, 150, 375, 750, 1000, 1250, and 1500, with corresponding viscosites of 1,1, 1.08, 1.6, 3.6, 6, 18, 65 centiPoise (mPa.s), respectively. Mortality was observed within minutes of intravenous dosing with 1250 and 1500 mg/kg. Clinical signs of dyspnea, decreased activity, flat body posture, and rough hair coat were observed in rats given 750 or 1000 mg/kg. Plasma potassium (K+) levels were increased at 24 hours post dose compared to pre-dose values at all doses tested. Histopathologic
evaluations of the heart, kidney and lungs revealed myocardial necrosis and inflammation, renal tubular necrosis and pulmonary histiocytosis with hemorrhage. Collectively, the clinical signs, serum potassium levels and histopathogical findings in rats given 750 and 1000 mg/kg were consistent with compromised tissue perfusion. No adverse findings were observed in rats given 7.5, 75, 150 or 375 mg/kg CrELP and 375 mg/kg was considered the no adverse effect level (NOAEL) in this study
Consumption of recommended food groups among children from medically underserved communities
This cross-sectional study of 2 to 12 year olds living in medically underserved areas examined the proportion of children meeting the food group intake recommendations for fruits, vegetables, total grains, dairy, and meat/meat alternatives by age group and body weight status. Based on 24-hour recalls collected between July 2004 and March of 2005, mean food group intake and deviation from the recommended intake amount were determined (actual intake minus recommended intake). Measured weight and height were used to calculate body mass index z-scores using the Centers for Disease Control and Prevention (CDC) growth charts. Analyses were conducted for two age groups (2 to 5 and 6 to 12 year olds) (n=214), by weight status categories (underweight or healthy weight ( 95th percentile)), and repeated for the subset of children with biologically plausible reports. The majority of children lived in lowincome households. More 2 to 5 year olds met intake recommendations compared to 6 to 12 year olds. Overall, the proportion of children meeting the food group intake recommendations was low with the exception of the meat group, which was met by 52% to 93% of children. There was a positive association between the proportion of younger children meeting the fruits or total grains recommendation and increasing body weight. The data support the importance of community-level nutrition intervention programs to improve children's diet quality in low income, medically underserved areas and suggest that such interventions may help reduce the risk of obesity. Originally published Journal of the American Dietetic Association, Vol. 109, No. 4, Apr 200
Classical realization of a strongly driven two-level system
A classical two-level system has been realized by coupling two propagation or two polarization modes of an optical ring resonator. This system can be driven by periodic modulation of either the coupling or the bare mode frequencies, at sufficient strength to violate the rotating-wave approximation (RWA) on resonance. Landau-Zener transitions, Rabi oscillation with non-RWA signature, and Autler-Townes doublets have been observed
Design and Bolometer Characterization of the SPT-3G First-year Focal Plane
During the austral summer of 2016-17, the third-generation camera, SPT-3G,
was installed on the South Pole Telescope, increasing the detector count in the
focal plane by an order of magnitude relative to the previous generation.
Designed to map the polarization of the cosmic microwave background, SPT-3G
contains ten 6-in-hexagonal modules of detectors, each with 269 trichroic and
dual-polarization pixels, read out using 68x frequency-domain multiplexing.
Here we discuss design, assembly, and layout of the modules, as well as early
performance characterization of the first-year array, including yield and
detector properties.Comment: Conference proceeding for Low Temperature Detectors 2017. Accepted
for publication: 27 August 201
How natural forest conversion affects insect biodiversity in the Peruvian Amazon : can agroforestry help?
The Amazonian rainforest is a unique ecosystem that comprises habitat for thousands of animal species. Over the last decades, the ever-increasing human population has caused forest conversion to agricultural land with concomitant high biodiversity losses, mainly near a number of fast-growing cities in the Peruvian Amazon. In this research, we evaluated insect species richness and diversity in five ecosystems: natural forests, multistrata agroforests, cocoa agroforests, annual cropping monoculture and degraded grasslands. We determined the relationship between land use intensity and insect diversity changes. Collected insects were taxonomically determined to morphospecies and data evaluated using standardized biodiversity indices. The highest species richness and abundance were found in natural forests, followed by agroforestry systems. Conversely, monocultures and degraded grasslands were found to be biodiversity-poor ecosystems. Diversity indices were relatively high for all ecosystems assessed with decreasing values along the disturbance gradient. An increase in land use disturbance causes not only insect diversity decreases but also complete changes in species composition. As agroforests, especially those with cocoa, currently cover many hectares of tropical land and show a species composition similar to natural forest sites, we can consider them as biodiversity reservoirs for some of the rainforest insect species
Improved rubidium atomic beam clock based on lamp-pumping and fluorescence-detection scheme
Chromatin signature of embryonic pluripotency is established during genome activation
available in PMC 2011 April 8.After fertilization the embryonic genome is inactive until transcription is initiated during the maternal–zygotic transition. This transition coincides with the formation of pluripotent cells, which in mammals can be used to generate embryonic stem cells. To study the changes in chromatin structure that accompany pluripotency and genome activation, we mapped the genomic locations of histone H3 molecules bearing lysine trimethylation modifications before and after the maternal–zygotic transition in zebrafish. Histone H3 lysine 27 trimethylation (H3K27me3), which is repressive, and H3K4me3, which is activating, were not detected before the transition. After genome activation, more than 80% of genes were marked by H3K4me3, including many inactive developmental regulatory genes that were also marked by H3K27me3. Sequential chromatin immunoprecipitation demonstrated that the same promoter regions had both trimethylation marks. Such bivalent chromatin domains also exist in embryonic stem cells and are thought to poise genes for activation while keeping them repressed. Furthermore, we found many inactive genes that were uniquely marked by H3K4me3. Despite this activating modification, these monovalent genes were neither expressed nor stably bound by RNA polymerase II. Inspection of published data sets revealed similar monovalent domains in embryonic stem cells. Moreover, H3K4me3 marks could form in the absence of both sequence-specific transcriptional activators and stable association of RNA polymerase II, as indicated by the analysis of an inducible transgene. These results indicate that bivalent and monovalent domains might poise embryonic genes for activation and that the chromatin profile associated with pluripotency is established during the maternal–zygotic transition.National Institutes of Health (U.S.) (grant 1R01 HG004069)National Institutes of Health (U.S.) (grant 5R01 GM56211)Human Frontier Science Program (Strasbourg, France) (LT-00090/2007)European Molecular Biology Organization (fellowship
Evaluation of Glycine max mRNA clusters
BACKGROUND: Clustering the ESTs from a large dataset representing a single species is a convenient starting point for a number of investigations into gene discovery, genome evolution, expression patterns, and alternatively spliced transcripts. Several methods have been developed to accomplish this, the most widely available being UniGene, a public domain collection of gene-oriented clusters for over 45 different species created and maintained by NCBI. The goal is for each cluster to represent a unique gene, but currently it is not known how closely the overall results represent that reality. UniGene's build procedure begins with initial mRNA clusters before joining ESTs. UniGene's results for soybean indicate a significant amount of redundancy among some sequences reported to be unique mRNAs. To establish a valid non-redundant known gene set for Glycine max we applied our algorithm to the clustering of only mRNA sequences. The mRNA dataset was run through the algorithm using two different matching stringencies. The resulting cluster compositions were compared to each other and to UniGene. Clusters exhibiting differences among the three methods were analyzed by 1) nucleotide and amino acid alignment and 2) submitting authors conclusions to determine whether members of a single cluster represented the same gene or not. RESULTS: Of the 12 clusters that were examined closely most contained examples of sequences that did not belong in the same cluster. However, neither the two stringencies of PECT nor UniGene had a significantly greater record of accuracy in placing paralogs into separate clusters. CONCLUSION: Our results reveal that, although each method produces some errors, using multiple stringencies for matching or a sequential hierarchical method of increasing stringencies can provide more reliable results and therefore allow greater confidence in the vast majority of clusters that contain only ESTs and no mRNA sequences
- …