69,819 research outputs found
The space environment - 100 to 500 kilometers
Aeronomy study of nitrogen ultraviolet radiation from IBC 3 auror
Spin fluctuations and superconductivity in powders of Fe_1+xTe_0.7Se_0.3 as a function of interstitial iron concentration
Using neutron inelastic scattering, we investigate the role of interstitial
iron on the low-energy spin fluctuations in powder samples of
Fe_{1+x}Te_{0.7}Se_{0.3}. We demonstrate how combining the principle of
detailed balance along with measurements at several temperatures allows us to
subtract both temperature-independent and phonon backgrounds from S(Q,\omega)
to obtain purely magnetic scattering. For small values of interstitial iron
(x=0.009(3)), the sample is superconducting (T_{c}=14 K) and displays a spin
gap of 7 meV peaked in momentum at wave vector q_{0}=(\pi,\pi) consistent with
single crystal results. On populating the interstitial iron sites, the
superconducting volume fraction decreases and we observe a filling in of the
low-energy magnetic fluctuations and a decrease of the characteristic wave
vector of the magnetic fluctuations. For large concentrations of interstitial
iron (x=0.048(2)) where the superconducting volume fraction is minimal, we
observe the presence of gapless spin fluctuations at a wave vector of
q_{0}=(\pi,0). We estimate the absolute total moment for the various samples
and find that the amount of interstitial iron does not change the total
magnetic spectral weight significantly, but rather has the effect of shifting
the spectral weight in Q and energy. These results show that the
superconducting and magnetic properties can be tuned by doping small amounts of
iron and are suggestive that interstitial iron concentration is also a
controlling dopant in the Fe_{1+x}Te_{1-y}Se_{y} phase diagram in addition to
the Te/Se ratio.Comment: (10 pages, 8 figures, to be published in Phys. Rev. B
The low energy expansion of the one-loop type II superstring amplitude
The one-loop four-graviton amplitude in either of the type II superstring
theories is expanded in powers of the external momenta up to and including
terms of order s^4 log s R^4, where R^4 denotes a specific contraction of four
linearized Weyl tensors and s is a Mandelstam invariant. Terms in this series
are obtained by integrating powers of the two-dimensional scalar field theory
propagator over the toroidal world-sheet as well as the moduli of the torus.
The values of these coefficients match expectations based on duality relations
between string theory and eleven-dimensional supergravity.Comment: harvmac (b), 25 pages, 3 eps figures. v2: Factors of 2 corrected.
Conclusion unchange
A cross sectional study of the prevalence, risk factors and population attributable fractions for limb and body lesions in lactating sows on commercial farms in England
Background: Lesions on sows' limbs and bodies are an abnormality that might impact on their welfare. The prevalence of and risks for limb and body lesions on lactating sows on commercial English pig farms were investigated using direct observation of the sows and their housing.
Results: The prevalence of lesions on the limbs and body were 93% (260/279) and 20% (57/288) respectively. The prevalence of limb and body lesions was significantly lower in outdoor-housed sows compared with indoor-housed sows. Indoor-housed sows had an increased risk of wounds (OR 6.8), calluses (OR 8.8) and capped hock (OR 3.8) on their limbs when housed on fully slatted floors compared with solid concrete floors. In addition, there was an increased risk of bursitis (OR 2.7), capped hock (OR 2.3) and shoulder lesions (OR 4.8) in sows that were unwilling to rise to their feet. There was a decreased risk of shoulder lesions (OR 0.3) and lesions elsewhere on the body (OR 0.2) in sows with more than 20 cm between their tail and the back of the crate compared with sows with less than 10 cm.
Conclusion: The sample of outdoor housed sows in this study had the lowest prevalence of limb and body lesions. In lactating sows housed indoors there was a general trend for an increased risk of limb and body lesions in sows housed on slatted floors compared with those housed on solid concrete floors with bedding. Sows that were less responsive to human presence and sows that had the least space to move within their crates had an additional increased risk of lesions
Connection between the Loop Variable Formalism and the Old Covariant Formalsm for the Open Bosonic String
The gauge invariant loop variable formalism and old covariant formalism for
bosonic open string theory are compared in this paper. It is expected that for
the free theory, after gauge fixing, the loop variable fields can be mapped to
those of the old covariant formalism in bosonic string theory, level by level.
This is verified explicitly for the first two massive levels. It is shown that
(in the critical dimension) the fields, constraints and gauge transformations
can all be mapped from one to the other. Assuming this continues at all levels
one can give general arguments that the tree S-matrix (integrated correlation
functions for on-shell physical fields) is the same in both formalisms and
therefore they describe the same physical theory (at tree level).Comment: Latex file, 24 page
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Convergence between the Penn Alcohol Craving Scale and diagnostic interview for the assessment of alcohol craving.
IntroductionThe Penn Alcohol Craving Scale (PACS) is one of the most widely used instruments to measure craving for alcohol. Recent research has suggested that scores on the PACS can be used as a "stand in" for the diagnostic criterion of alcohol craving with a proposed cutoff of >20 on the PACS indicating a "positive" alcohol craving symptom. The present study examined the convergence between the PACS and face-to-face diagnostic interview for the assessment of alcohol craving.MethodA sample of non-treatment seeking heavy drinkers (N = 338) enrolled in experimental studies of AUD completed the PACS as well as a face-to-face diagnostic interview for AUD, which included the craving item from the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA).ResultsUsing the PACS cut-off score of >20, 12.9% (N = 43) of the sample met criteria for alcohol craving compared to 21% (N = 74) of the sample meeting criteria based on the diagnostic interview. Using the PACS cutoff of >20, sensitivity (i.e., true positive rate) was 41% and specificity (i.e., true negative rate) was 95%. Exploratory analyses suggested that a cut-off score of ≥15 achieved the optimal balance of sensitivity (67%) and specificity (81%) in our sample.ConclusionsAdvancing the assessment of alcohol craving and the conversion from DSM-IV to DSM-5 diagnostic criteria represents an important research direction. The present study recommends that a PACS score cut off of ≥15 should be used as an indicator of clinically significant alcohol craving in community samples of non-treatment seekers
The neutral gas in the environs of the Geminga gamma-ray pulsar
We present a high-resolution (24 arcsec) study of the HI interstellar gas
distribution around the radio-quiet neutron star Geminga. Based on Very Large
Array (VLA) and MPIfR Effelsberg telescope data, we analyzed a 40' x 40' field
around Geminga. These observations have revealed the presence of a neutral gas
shell, 0.4 pc in radius, with an associated HI mass of 0.8 Msun, which
surrounds Geminga at a radial velocity compatible with the kinematical distance
of the neutron star. In addition, morphological agreement is observed between
the internal face of the HI shell and the brightest structure of Geminga's tail
observed in X-rays.We explore the possibility that this morphological agreement
is the result of a physical association.Comment: One tarfile including a Latex file (7 pages) and two figures. Paper
accepted for publication in Advances in Space Research; typos corrected;
changes in section Results and Discussion after referee's suggestions. S.
Johnston's affilation correcte
Evaluating observer agreement of scoring systems for foot integrity and footrot lesions in sheep
Background:
A scoring scale with five ordinal categories is used for visual diagnosis of footrot in sheep and to study its epidemiology and control. More recently a 4 point ordinal scale has been used by researchers to score foot integrity (wall and sole horn damage) in sheep. There is no information on observer agreement using either of these scales. Observer agreement for ordinal scores is usually estimated by single measure values such as weighted kappa or Kendall’s coefficient of concordance which provide no information where the disagreement lies. Modeling techniques such as latent class models provide information on both observer bias and whether observers have different thresholds at which they change the score given. In this paper we use weighted kappa and located latent class modeling to explore observer agreement when scoring footrot lesions (using photographs and videos) and foot integrity (using post mortem specimens) in sheep. We used 3 observers and 80 photographs and videos and 80 feet respectively.
Results:
Both footrot and foot integrity scoring scales were more consistent within observers than between. The weighted kappa values between observers for both footrot and integrity scoring scales ranged from moderate to substantial. There was disagreement between observers with both observer bias and different thresholds between score values. The between observer thresholds were different for scores 1 and 2 for footrot (using photographs and videos) and for all scores for integrity (both walls and soles). The within observer agreement was higher with weighted kappa values ranging from substantial to almost perfect. Within observer thresholds were also more consistent than between observer thresholds. Scoring using photographs was less variable than scoring using video clips or feet.
Conclusions:
Latent class modeling is a useful method for exploring components of disagreement within and between observers and this information could be used when developing a scoring system to improve reliability
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