5,681 research outputs found
A possible contribution to CMB anisotropies at high l from primordial voids
We present preliminary results of an analysis into the effects of primordial
voids on the cosmic microwave background (CMB). We show that an inflationary
bubble model of void formation predicts excess power in the CMB angular power
spectrum that peaks between 2000 < l < 3000. Therefore, voids that exist on or
close to the last scattering surface at the epoch of decoupling can contribute
significantly to the apparent rise in power on these scales recently detected
by the Cosmic Background Imager (CBI).Comment: 5 pages, 3 figures. MNRAS accepted versio
A cross-cultural re-evaluation of the Exercise Addiction Inventory (EAI) in five countries
Research into the detrimental effects of excessive exercise has been conceptualized in a number of similar ways, including ‘exercise addiction’ , ‘exercise dependence’ , ‘obligatory exercising’, ‘exercise abuse’, and ‘compulsive exercise’. Among the most currently used (and psychometrically valid and reliable) instruments is the Exercise Addiction Inventory (EAI). The present study aimed to further explore the psychometric properties of the EAI by combining the datasets of a number of surveys carried out in five different countries (Denmark, Hungary, Spain, UK, and US) that have used the EAI with a total sample size of 6,031 participants. A series of multigroup confirmatory factor analyses (CFAs) were carried out examining configural invariance, metric invariance, and scalar invariance. The CFAs using the combined dataset supported the configural invariance and metric invariance but not scalar invariance. Therefore, EAI factor scores from five countries are not comparable because the use or interpretation of the scale was different in the five nations. However, the covariates of exercise addiction can be studied from a cross-cultural perspective because of the metric invariance of the scale. Gender differences among exercisers in the interpretation of the scale also emerged. The implications of the results are discussed, and it is concluded that the study’s findings will facilitate a more robust and reliable use of the EAI in future research
Response of Phytoplankton Photophysiology to Varying Environmental Conditions in the Sub-Antarctic and Polar Frontal Zone
Climate-driven changes are expected to alter the hydrography of the Sub-Antarctic Zone (SAZ) and Polar Frontal Zone (PFZ)
south of Australia, in which distinct regional environments are believed to be responsible for the differences in
phytoplankton biomass in these regions. Here, we report how the dynamic influences of light, iron and temperature, which
are responsible for the photophysiological differences between phytoplankton in the SAZ and PFZ, contribute to the
biomass differences in these regions. High effective photochemical efficiency of photosystem II (F
0
q/F
0
mw0.4), maximum
photosynthesis rate (PB
max), light-saturation intensity (Ek), maximum rate of photosynthetic electron transport (1/tPSII), and
low photoprotective pigment concentrations observed in the SAZ correspond to high chlorophyll a and iron
concentrations. In contrast, phytoplankton in the PFZ exhibits low F
0
q/F
0
m (* 0.2) and high concentrations of
photoprotective pigments under low light environment. Strong negative relationships between iron, temperature, and
photoprotective pigments demonstrate that cells were producing more photoprotective pigments under low temperature
and iron conditions, and are responsible for the low biomass and low productivity measured in the PFZ. As warming and
enhanced iron input is expected in this region, this could probably increase phytoplankton photosynthesis in this region.
However, complex interactions between the biogeochemical processes (e.g. stratification caused by warming could prevent
mixing of nutrients), which control phytoplankton biomass and productivity, remain uncertain
An Exploration of Deep-Learning Based Phenotypic Analysis to Detect Spike Regions in Field Conditions for UK Bread Wheat
Wheat is one of the major crops in the world, with a global demand expected to reach 850 million tons by 2050 that is clearly outpacing current supply. The continual pressure to sustain wheat yield due to the world’s growing population under fluctuating climate conditions requires breeders to increase yield and yield stability across environments. We are working to integrate deep learning into field-based phenotypic analysis to assist breeders in this endeavour. We have utilised wheat images collected by distributed CropQuant phenotyping workstations deployed for multiyear field experiments of UK bread wheat varieties. Based on these image series, we have developed a deep-learning based analysis pipeline to segment spike regions from complicated backgrounds. As a first step towards robust measurement of key yield traits in the field, we present a promising approach that employ Fully Convolutional Network (FCN) to perform semantic segmentation of images to segment wheat spike regions. We also demonstrate the benefits of transfer learning through the use of parameters obtained from other image datasets. We found that the FCN architecture had achieved a Mean classification Accuracy (MA) >82% on validation data and >76% on test data and Mean Intersection over Union value (MIoU) >73% on validation data and and >64% on test datasets. Through this phenomics research, we trust our attempt is likely to form a sound foundation for extracting key yield-related traits such as spikes per unit area and spikelet number per spike, which can be used to assist yield-focused wheat breeding objectives in near future
Implementation of classical communication in a quantum world
Observations of quantum systems carried out by finite observers who
subsequently communicate their results using classical data structures can be
described as "local operations, classical communication" (LOCC) observations.
The implementation of LOCC observations by the Hamiltonian dynamics prescribed
by minimal quantum mechanics is investigated. It is shown that LOCC
observations cannot be described using decoherence considerations alone, but
rather require the \textit{a priori} stipulation of a positive operator-valued
measure (POVM) about which communicating observers agree. It is also shown that
the transfer of classical information from system to observer can be described
in terms of system-observer entanglement, raising the possibility that an
apparatus implementing an appropriate POVM can reveal the entangled
system-observer states that implement LOCC observations.Comment: 17 pages, 2 figures; final versio
Galactic Magnetic Turbulence from Radio data
Fluctuations in the Galactic synchrotron emission can be traced by the
angular power spectrum of radio maps at low multipoles. At frequencies below
few GHz, large-scale anisotropies are mainly induced by magnetic field
turbulence. By performing an analysis of five radio maps, we extract
constraints on turbulence spectral index and halo scale. Results favour a power
spectrum significantly flatter than for 3D Kolmogorov-like turbulence, and a
thin halo. This can be interpreted as an indication supporting non-conventional
models of propagation of cosmic-ray particles in the Galaxy, or as a suggestion
of a spectral-index break in the observed magnetic turbulence power spectrum.Comment: 15 pages, 3 figures. v2: discussions and references improved, to
appear in Astropart.Phys.
Obsessive and harmonious passion in physically active Spanish and Hungarian men and women: a brief report on cultural and gender differences
Increased research on passion in physical activity calls for direct examination of possible mediating variables that could influence the research outcome. The present study using a two by-two (nation by gender) between-participants design, examined whether gender and/or cultural differences in obsessive- and harmonious passion were present in Spanish and Hungarian physically active individuals. Participants (n=1,002) completed the Passion Scale, reported their gender, age, and weekly hours of physical activity. Multivariate analysis of covariance revealed that the experiencing of physical activity-related obsessive- and harmonious passion differed between the two countries and Hungarian women scored significantly higher on harmonious and obsessive passion than Spanish women. However, Hungarian men only scored significantly higher on obsessive passion, but not harmonious passion compared to Spanish men. These results suggest that the moderating role of gender and cultural differences should be addressed more carefully in conducting and interpreting results of research concerned with passion in physical activity
Assessing Internet addiction using the parsimonious Internet addiction components model - a preliminary study [forthcoming]
Internet usage has grown exponentially over the last decade. Research indicates that excessive Internet use can lead to symptoms associated with addiction. To date, assessment of potential Internet addiction has varied regarding populations studied and instruments used, making reliable prevalence estimations difficult. To overcome the present problems a preliminary study was conducted testing a parsimonious Internet addiction components model based on Griffiths’ addiction components (2005), including salience, mood modification, tolerance, withdrawal, conflict, and relapse. Two validated measures of Internet addiction were used (Compulsive Internet Use Scale [CIUS], Meerkerk et al., 2009, and Assessment for Internet and Computer Game Addiction Scale [AICA-S], Beutel et al., 2010) in two independent samples (ns = 3,105 and 2,257). The fit of the model was analysed using Confirmatory Factor Analysis. Results indicate that the Internet addiction components model fits the data in both samples well. The two sample/two instrument approach provides converging evidence concerning the degree to which the components model can organize the self-reported behavioural components of Internet addiction. Recommendations for future research include a more detailed assessment of tolerance as addiction component
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