7,112 research outputs found
Metastable Flux Configurations and de Sitter Spaces
We derive stability conditions for the critical points of the no-scale scalar
potential governing the dynamics of the complex structure moduli and the
axio-dilaton in compactifications of type IIB string theory on Calabi-Yau
three-folds. We discuss a concrete example of a T^6 orientifold. We then
consider the four-dimensional theory obtained from compactifications of type
IIB string theory on non-geometric backgrounds which are mirror to rigid
Calabi-Yau manifolds and show that the complex structure moduli fields can be
stabilized in terms of H_{RR} only, i.e. with no need of orientifold
projection. The stabilization of all the fields at weak coupling, including the
axio-dilaton, may require to break supersymmetry in the presence of H_{NS} flux
or corrections to the scalar potential.Comment: 24 page
Undergraduate Research: The Jetmore Food Center
The Jetmore Food Center aids the community by providing food to the citizens of Jetmore. In general, the majority of those that shop in the Jetmore Food Center are above the age of 40, but the store serves to customers of all ages. The store opens at 8 A.M and stays open until 8 P.M at night six days a week. In the past, stores in Jetmore closed at 6 P.M every day and closed on Sundays. This caused problems for many residents of Jetmore, as many work in Dodge City and did not return to Jetmore until the evening. Like most small townâs grocery stores, the Jetmore Food Center donates food and drinks to the school, the hospital, as well as clubs and organizations that hold special events in Jetmore. Once again, aiding and partaking in events in the community further strengthens townspeopleâs confidence in their local grocer, which in turn helps a store succeed. Also, unlike chain stores, the profit dollars made from a small-town grocery store circulate back into the community. Without a doubt, the Jetmore Food Center keeps Jetmore a successful small town in Kansas. From offering quality food at reasonable prices, to providing jobs for the youth and teaching them vital skills for adulthood, the Jetmore Food Center is the lifeblood of the community of Jetmore
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Low-level mediation of directionally specific motion after-effects: motion perception is not necessary
Previous psychophysical experiments with normal human observers have shown that adaptation to a moving dot stream causes directionally specific repulsion in the perceived angle of a subsequently viewed, moving probe. In this paper, we used a 2AFC task with roving pedestals to determine the conditions necessary and sufficient for producing directionally specific repulsion with compound adaptors, each ofwhich contains two oppositely moving, differently colored, component streams. Experiment 1 provides a demonstration of repulsion between single-component adaptors and probes moving at approximately 90° or 270°. In Experiment 2 oppositely moving dots in the adaptor were paired to preclude the appearance of motion. Nonetheless, repulsion remained strong when the angle betweeneach probe stream and one component was approximately 30°. In Experiment 3 adapting dot-pairs were kept stationary during their limited lifetimes. Their orientation content alone proved insufficient for producing repulsion. In Experiments 4-6 the angle between probe and both adapting components was approximately 90°or 270°. Directional repulsion was found when observers were asked to visually track one of the adapting components (Experiment 6), but not when observers were asked to attentionally track it (Experiment 5), nor while passively viewing the adaptor (Experiment 4). Our results are consistent with a low-level mechanism for motion adaptation. It is not selective for stimulus color and it is not susceptible to attentional modulation.The most likely cortical locus of adaptation is area V1
Major Element Chemical Heterogeneity in Geo2 Olivine Micro-Beam Reference Material: A Spatial Approach to Quantifying Heterogeneity in Primary Reference Materials
A 270 spot-analysis study was conducted across a large (ca. 1200 ÎŒm x 1200 ÎŒm) chip of Geo2 olivine from a commercially available GEO Mk2 block (P and H Developments 2016) which revealed a 8.7% relative range in FeO abundance. Interleaved and overlapping grids of different resolutions were measured sequentially to prove spatial patterns are not due to drift or other external sources of error. Results were mapped and interpolated using commercially available geographical information system software, such that composition could be predicted according to location with high accuracy. The simple, systematic zonation pattern observed demonstrates that useful-sized regions of acceptable homogeneity do exist for some elements. This knowledge allows a user to target individual regions of a characterised chip for use as distinct measurement standards. As analysis times decrease and datasets grow, this approach may maximise laboratory efficiency by characterising large chips and extending time between standard block re-polish and coating, particularly in those cases where the avoidance of prior beam damage is a key concern
Montmorency cherry supplementation improves 15-km cycling time-trial performance
This is the final version. Available on open access from Springer Verlag via the DOI in this recordAim: Montmorency cherries are rich in polyphenols that possess antioxidant, anti-inflammatory and vasoactive properties. We investigated whether 7 d Montmorency cherry powder supplementation improved cycling time-trial (TT) performance. Methods: 8 trained male cyclists (VÌO2peak: 62.3 ± 10.1 ml.kg-1.min-1) completed 10-min steady state (SS) cycling at ~65% VÌO2peak followed by a 15-km TT on two occasions. Participants consumed 6 pills per day (Montmorency cherry powder, MC; anthocyanin 257 mg·dâ1 or dextrose powder, PL) for a 7 d period, 3 pills in the morning and evening. Capillary blood [lactate] was measured at baseline, post SS and post TT. Pulmonary gas exchange and tissue oxygenation index (TOI) of m.vastus lateralis via near-infrared spectroscopy, were measured throughout. Results: TT completion time was 4.6 ± 2.9% faster following MC (1506 ± 86 s) supplementation compared to PL (1580 ± 102 s; P=0.004). Blood [lactate] was significantly higher in MC after SS (PL: 4.4 ± 2.1 vs. MC: 6.7 ± 3.3 mM, P=0.017) alongside an elevated baseline TOI (PL: 68.7 ± 2.1 vs. MC: 70.4 ± 2.3%, P=0.018). Discussion: Montmorency cherry supplementation improved 15-km cycling TT performance. This improvement in exercise performance was accompanied by enhanced muscle oxygenation suggesting that the vasoactive properties of the Montmorency cherry polyphenols may underpin the ergogenic effects
Genetic variants in ALDH1B1 and alcohol dependence risk in a British and Irish population: A bioinformatic and genetic study
Alcohol is metabolized in the liver via the enzymes alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Polymorphisms in the genes encoding these enzymes, which are common in East Asian populations, can alter enzyme kinetics and hence the risk of alcohol dependence and its sequelae. One of the most important genetic variants, in this regards, is the single nucleotide polymorphism (SNP) rs671 in ALDH2, the gene encoding the primary acetaldehyde metabolizing enzyme ALDH2. However, the protective allele of rs671 is absent in most Europeans although ALDH1B1, which shares significant sequence homology with ALDH2, contains several, potentially functional, missense SNPs that do occur in European populations. The aims of this study were: (i) to use bioinformatic techniques to characterize the possible effects of selected variants in ALDH1B1 on protein structure and function; and, (ii) to genotype three missense and one stop-gain, protein-altering, non-synonymous SNPs in 1478 alcohol dependent cases and 1254 controls of matched British and Irish ancestry. No significant allelic associations were observed between the three missense SNPs and alcohol dependence risk. The minor allele frequency of rs142427338 (Gln378Ter) was higher in alcohol dependent cases than in controls (allelic P = 0.19, OR = 2.98, [0.62-14.37]) but as this SNP is very rare the study was likely underpowered to detect an association with alcohol dependence risk. This potential association will needs to be further evaluated in other large, independent European populations
The identification of markers for Geoforensic HPLC profiling at close proximity sites
Soil is a highly transferable source of trace physical material that is both persistent in the environment and varied in composition. This inherent variability can provide useful information to determine the geographical origin of a questioned sample or when comparing and excluding samples, since the composition of soil is dependent on geographical factors such as climate, bedrock geology and land use. Previous studies have limited forensic relevance due to the requirement for large sample amounts and unrealistic differences between the land use and geographical location of the sample sites. In addition the philosophical differences between the disciplines of earth sciences, for which most analytical techniques have been designed, and forensic sciences, particularly with regard to sample preparation and data interpretation have not been fully considered. This study presents an enhanced technique for the analysis of organic components of geoforensic samples by improving the sample preparation and data analysis strategies used in previous research into the analysis of soil samples by high performance liquid chromatography (HPLC). This study provides two alternative sets of marker peaks to generate HPLC profiles which allow both easy visual comparison of samples and the correct assignment of 100% of the samples to their location of origin when discriminating between locations of interest in multivariate statistical analyses. This technique thereby offers an independent form of analysis that is complementary to inorganic geoforensic techniques and offers an easily accessible method for discriminating between close proximity forensically relevant locations
The determination of the mass of a Magellanic Cloud planetary nebula by speckle interferometry
We have resolved a Magellanic Cloud planetary nebula by speckle interferometry for the first time. Our observations of SMC N2 show it to have a double-ring structure, the rings having angular radii of 0.22 and 0.38 arcsec, corresponding to absolute radii of 0.06 and 0.10 pc. Our speckle observations of the galactic planetary nebula Vy 2â2 show a ring of angular diameter 0.4 arcsec, in agreement with previous VLA radio data. The radial hydrogen density profile for SMC N2 is determined and masses of 0.09Mâ and 0.27Mâ for the inner and outer shells respectively are derived, so that the total mass of this optically thin nebula is 0.36Mââ . The nebular expansion velocity of SMC N2 has been derived from a high-resolution spectrum of the [O III] 5007 Ă
line and expansion ages of between 5000 and 12 000 yr have been derived for the shells. A reanalysis of the available nebular data leads us to derive a central star effective temperature of 110 000 K and a luminosity of 4340Lââ , corresponding to a stellar mass of 0.59Mââ , from a comparison with published evolutionary tracks. The stellar evolutionary age since leaving the AGB is about 8000 yr, consistent with the nebublar expansion age
A validated severity score for haemorrhoids as an essential prerequisite for future haemorrhoid trials.
BACKGROUND: There is a lack of standardised outcomes for haemorrhoidal disease making comparison between trials difficult. A need for a very well validated severity score is essential to facilitate meta-analysis of comparative studies, enabling evidence-based clinical practice. METHODS: The Hubble trial provides a large cohort of patients with haemorrhoidal disease randomised to rubber band ligation (RBL) or haemorrhoidal artery ligation. The haemorrhoid severity score (HSS) was collected on each patient at baseline, 6Â weeks and 1Â year after intervention. This allows for the responsiveness of the HSS instrument to be examined and compared with a more specific instrument, the Vaizey incontinence score (also collected). Responsiveness was tested using four methods (effect size, standardised response means (SRM), significance of change, and responsiveness statistic). RESULTS: The four tests of responsiveness demonstrated that the HSS was more responsive to changes in the patient's health status following both of the interventions compared to the Vaizey questionnaire. For example, between baseline and 6Â weeks, the RBL intervention effect size scores and SRM calculations indicated a non-significant small amount of change (0.20 and 0.16 respectively). However, using the HSS, the effect size and SRM demonstrated a large magnitude of change (1.12 and 1.01, respectively) which was significant. Similar results were observed at 1Â year. Significance of change scores and the index of responsiveness were also higher for the HSS questionnaire than the Vaizey across both treatment modalities. CONCLUSIONS: The HSS is a highly responsive tool for the detection of changes in haemorrhoid symptoms. It should form an essential patient-reported outcome tool for future studies on haemorrhoidal disease
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