289 research outputs found
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Sleep Problems and Gambling Disorder: Cross-Sectional Relationships in a Young Cohort
Aims: To investigate the potential association between gambling disorder and symptoms of sleep problems (including insomnia and excessive daytime sleepiness). It was hypothesised that, compared to controls, individuals with gambling disorder would have significantly greater disturbance of sleep, as indicated by increased scores in: (1) sleep items on the Hamilton Anxiety Rating Scale (HAM-A) and Hamilton Rating Scale for Depression (HAM-D); (2) total score on the HAM-A and HAM-D; and (3) the Epworth Sleepiness Scale (ESS). Methods: Secondary analysis of previously published data from 152 young adults, aged 18-29 years. Individuals were stratified into three groups: controls, those at risk of gambling disorder, and those with gambling disorder. One-way ANOVAs with post-hoc tests were conducted to determine whether groups differed significantly in sleep item scores and total scores of the HAM-A and HAM-D, and the ESS. Results: HAM-D scale insomnia item scores were significantly higher in the disorder group, when compared to controls, this being particularly marked for middle and late insomnia. The HAM-A item score indicated significantly worse sleep quality in the disorder group, compared to at risk and control groups. Total HAM-A and HAM-D scores were significantly higher in the disorder group, but ESS scores did not differ significantly. Conclusion: Measures of disruptions in sleep were significantly higher in gambling disorder than controls. Anxiety and depressive symptom severity was also significantly higher in the gambling disorder group. Further research could have implications for identification and treatment of sleep disorders and psychiatric comorbidities in gambling disorder.</p
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From Business Model to Business Modelling: Modularity and Manipulation
The concept of modularity has gained considerable traction in technology studies as a way to conceive, describe and innovate complex systems, such as product design or organizational structures. In the recent literature, technological modularity has often been intertwined with business model innovation, and scholarship has started investigating how modularity in technology affects changes in business models, both at the cognitive and activity system levels. Yet we still lack a theoretical definition of what modularity is in the business model domain. Business model innovation also encompasses different possibilities of modeling businesses, which are not clearly understood nor classified. We ask when, how and if modularity theory can be extended to business models in order to enable effective and efficient modeling. We distinguish theoretically between modularity for technology and for business models, and investigate the key processes of modularization and manipulation. We introduce the basic operations of business modeling via modular operators adapted from the technological modularity domain, using iconic examples to develop an analogical reasoning between modularity in technology and in business models. Finally, we discuss opportunities for using modularity theory to foster the understanding of business models and modeling, and develop a challenging research agenda for future investigations
Electron Capture Strength for {60,62}Ni and {58,60,62,64}Ni(p,n){58,60,62,64}Cu reactions at 134.3 MeV
Background: The strength of electron capture for medium mass nuclei has a
significant effect on the evolution of supernovae. There is insufficient
knowledge of these strengths and very little data for important radioactive
nuclei. Purpose: Determine whether it is feasible to obtain EC strength from
studies of T_o+1 excitations in (p,n) reactions, and whether this might yield
information for radioactive nuclei. Methods: Cross sections for the
{58,60,62,64}Ni(p,n){58,60,62,64}Cu reactions were measured over the angular
range of 0.3 deg to 11.6 deg at 134.3 MeV using the IUCF neutron time-of-flight
facility. esults: The T_o+1 excitations in {60,62}Ni were identified by
comparison with inelastic proton scattering spectra, their B(GT) were
extracted, and the corresponding electron capture rates in supernovae were
calculated. Data from the TRIUMF (n,p) experiments at 198 MeV were reanalyzed;
the electron capture rates for the reanalyzed data are in moderately good
agreement with the higher resolution (p,n) results, but differ in detail. The
possibility of future measurements with radioactive nuclei was considered.
Conclusions: It is possible to determine electron capturestrength from (p,n)
experiments. This approach may make it possible to obtain electron capture
strength for radioactive nuclei by studying (p,n) reactions in inverse
kinematics.Comment: Submitted to Physical Review
Storm-induced inner-continental shelf circulation and sediment transport : Long Bay, South Carolina
This paper is not subject to U.S. copyright. The definitive version was published in Continental Shelf Research 42 (2012): 51â63, doi:10.1016/j.csr.2012.05.001.Long Bay is a sediment-starved, arcuate embayment located along the US East Coast connecting both South and North Carolina. In this region the rates and pathways of sediment transport are important because they determine the availability of sediments for beach nourishment, seafloor habitat, and navigation. The impact of storms on sediment transport magnitude and direction were investigated during the period October 2003âApril 2004 using bottom mounted flow meters, acoustic backscatter sensors and rotary sonars deployed at eight sites offshore of Myrtle Beach, SC, to measure currents, water levels, surface waves, salinity, temperature, suspended sediment concentrations, and bedform morphology. Measurements identify that sediment mobility is caused by waves and wind driven currents from three predominant types of storm patterns that pass through this region: (1) cold fronts, (2) warm fronts and (3) low-pressure storms. The passage of a cold front is accompanied by a rapid change in wind direction from primarily northeastward to southwestward. The passage of a warm front is accompanied by an opposite change in wind direction from mainly southwestward to northeastward. Low-pressure systems passing offshore are accompanied by a change in wind direction from southwestward to southeastward as the offshore storm moves from south to north.
During the passage of cold fronts more sediment is transported when winds are northeastward and directed onshore than when the winds are directed offshore, creating a net sediment flux to the northâeast. Likewise, even though the warm front has an opposite wind pattern, net sediment flux is typically to the northâeast due to the larger fetch when the winds are northeastward and directed onshore. During the passage of low-pressure systems strong winds, waves, and currents to the south are sustained creating a net sediment flux southwestward. During the 3-month deployment a total of 8 cold fronts, 10 warm fronts, and 10 low-pressure systems drove a net sediment flux southwestward. Analysis of a 12-year data record from a local buoy shows an average of 41 cold fronts, 32 warm fronts, and 26 low-pressure systems per year. The culmination of these events would yield a cumulative net inner-continental shelf transport to the southâwest, a trend that is further verified by sediment textural analysis and bedform morphology on the inner-continental shelf.This research was funded by the South Carolina Coastal
Erosion Project(http://pubs.usgs.gov/fs/2005/3041/), a cooperative study supported by the US Geological Survey and the South
Carolina Sea Grant Consortium(Sea Grant Project no:R/CP-11)
Multimodel climate and variability of the stratosphere
The stratospheric climate and variability from simulations of sixteen chemistryâclimate models is evaluated. On average the polar night jet is well reproduced though its variability is less well reproduced with a large spread between models. Polar temperature biases are less than 5 K except in the Southern Hemisphere (SH) lower stratosphere in spring. The accumulated area of low temperatures responsible for polar stratospheric cloud formation is accurately reproduced for the Antarctic but underestimated for the Arctic. The shape and position of the polar vortex is well simulated, as is the tropical upwelling in the lower stratosphere. There is a wide model spread in the frequency of major sudden stratospheric warnings (SSWs), late biases in the breakup of the SH vortex, and a weak annual cycle in the zonal wind in the tropical upper stratosphere. Quantitatively, âmetricsâ indicate a wide spread in model performance for most diagnostics with systematic biases in many, and poorer performance in the SH than in the Northern Hemisphere (NH). Correlations were found in the SH between errors in the final warming, polar temperatures, the leading mode of variability, and jet strength, and in the NH between errors in polar temperatures, frequency of major SSWs, and jet strength. Models with a stronger QBO have stronger tropical upwelling and a colder NH vortex. Both the qualitative and quantitative analysis indicate a number of common and longâstanding model problems, particularly related to the simulation of the SH and stratospheric variability
The Impact of the C-Terminal Domain on the Interaction of Human DNA Topoisomerase II α and ÎČ with DNA
<b>Background</b>
Type II DNA topoisomerases are essential, ubiquitous enzymes that act to relieve topological problems arising in DNA from normal cellular activity. Their mechanism of action involves the ATP-dependent transport of one DNA duplex through a transient break in a second DNA duplex; metal ions are essential for strand passage. Humans have two isoforms, topoisomerase IIα and topoisomerase IIÎČ, that have distinct roles in the cell. The C-terminal domain has been linked to isoform specific differences in activity and DNA interaction.
<b>Methodology/Principal Findings</b>
We have investigated the role of the C-terminal domain in the binding of human topoisomerase IIα and topoisomerase IIÎČ to DNA in fluorescence anisotropy assays using full length and C-terminally truncated enzymes. We find that the C-terminal domain of topoisomerase IIÎČ but not topoisomerase IIα affects the binding of the enzyme to the DNA. The presence of metal ions has no effect on DNA binding. Additionally, we have examined strand passage of the full length and truncated enzymes in the presence of a number of supporting metal ions and find that there is no difference in relative decatenation between isoforms. We find that calcium and manganese, in addition to magnesium, can support strand passage by the human topoisomerase II enzymes.
<b>Conclusions/Significance</b>
The C-terminal domain of topoisomerase IIÎČ, but not that of topoisomerase IIα, alters the enzyme's KD for DNA binding. This is consistent with previous data and may be related to the differential modes of action of the two isoforms in vivo. We also show strand passage with different supporting metal ions for human topoisomerase IIα or topoisomerase IIÎČ, either full length or C-terminally truncated. They all show the same preferences, whereby Mg > Ca > Mn
Evaluation of the inter-annual variability of stratospheric chemical composition in chemistry-climate models using ground-based multi species time series
The variability of stratospheric chemical composition occurs on a broad spectrum of timescales, ranging from day to decades. A large part of the variability appears to be driven by external forcings such as volcanic aerosols, solar activity, halogen loading, levels of greenhouse gases (GHG), and modes of climate variability (quasi-biennial oscillation (QBO), El Niño-Southern Oscillation (ENSO)). We estimate the contributions of different external forcings to the interannual variability of stratospheric chemical composition and evaluate how well 3-D chemistry-climate models (CCMs) can reproduce the observed response-forcing relationships. We carry out multivariate regression analyses on long time series of observed and simulated time series of several traces gases in order to estimate the contributions of individual forcings and unforced variability to their internannual variability. The observations are typically decadal time series of ground-based data from the international Network for the Detection of Atmospheric Composition Change (NDACC) and the CCM simulations are taken from the CCMVal-2 REF-B1 simulations database. The chemical species considered are column O3, HCl, NO2, and N2O. We check the consistency between observations and model simulations in terms of the forced and internal components of the total interannual variability (externally forced variability and internal variability) and identify the driving factors in the interannual variations of stratospheric chemical composition over NDACC measurement sites. Overall, there is a reasonably good agreement between regression results from models and observations regarding the externally forced interannual variability. A much larger fraction of the observed and modelled interannual variability is explained by external forcings in the tropics than in the extratropics, notably in polar regions. CCMs are able to reproduce the amplitudes of responses in chemical composition to specific external forcings. However, CCMs tend to underestimate very substantially the internal variability and hence the total interannual variability for almost all species considered. This lack of internal variability in CCMs might partly originate from the surface forcing of these CCMs by analysed SSTs. The results illustrate the potential of NDACC ground-based observations for evaluating CCMs
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