230 research outputs found
Collins effect and single spin azimuthal asymmetries in the HERMES and COMPASS experiments
Predictions are made for single spin azimuthal asymmetries due to the Collins
effect in pion production from semi-inclusive deeply inelastic scattering off
transversely and longitudinally polarized targets for the HERMES and COMPASS
experiments. The x-dependence of the asymmetries is evaluated using the parton
distribution functions from the chiral quark-soliton model. The overall
normalization of the predicted asymmetries is determined by the information on
the Collins fragmentation function extracted from previous HERMES data on
azimuthal asymmetries from a longitudinally polarized target. The single spin
asymmetries from the transversely polarized proton target are found to be about
20% for positive and neutral pions both at HERMES and COMPASS. For a
longitudinally polarized target we obtain for COMPASS a sin(phi) asymmetry of
1% and a sin(2phi) asymmetry of about 3%.Comment: 10 pages, 9 figures, Ref.[29] adde
Measurement of the LT-asymmetry in \pi^0 electroproduction at the energy of the \Delta (1232) resonance
The reaction p(e,e'p)pi^0 has been studied at Q^2=0.2 (GeV/c)^2 in the region
of W=1232 MeV. From measurements left and right of q, cross section asymmetries
\rho_LT have been obtained in forward kinematics \rho_LT(\theta_\pi^0=20deg) =
(-11.68 +/- 2.36_stat +/- 2.36_sys)$ and backward kinematics
\rho_LT(\theta_\pi^0=160deg) =(12.18 +/- 0.27_stat +/- 0.82_sys). Multipole
ratios \Re(S_1+^* M_1+)/|M_1+|^2 and \Re(S_0+^* M_1+)/|M_1+|^2 were determined
in the framework of the MAID2003 model. The results are in agreement with older
data. The unusally strong negative \Re(S_0+^* M_1+)/|M_1+|^2 required to bring
also the result of Kalleicher et al. in accordance with the rest of the data is
almost excluded.Comment: 7 pages, 7 figures, 4 tables. Changed content. Accepted for
publication in EPJ
Generalized parton distributions from nucleon form factor data
We present a simple empirical parameterization of the x- and t-dependence of
generalized parton distributions at zero skewness, using forward parton
distributions as input. A fit to experimental data for the Dirac, Pauli and
axial form factors of the nucleon allows us to discuss quantitatively the
interplay between longitudinal and transverse partonic degrees of freedom in
the nucleon ("nucleon tomography"). In particular we obtain the transverse
distribution of valence quarks at given momentum fraction x. We calculate
various moments of the distributions, including the form factors that appear in
the handbag approximation to wide-angle Compton scattering. This allows us to
estimate the minimal momentum transfer required for reliable predictions in
that approach to be around |t|~3 GeV^2. We also evaluate the valence
contributions to the energy-momentum form factors entering Ji's sum rule.Comment: 69 pages, 36 figures. v2: small improvements in text and figures;
references adde
Economic assessment of use of pond ash in pavements
The paper introduces a new type of industrial waste-based subbase material which can replace conventional subbase material (CSM) in pavement construction. Utilisation of this industrial waste, namely pond coal ash produced from a thermal power plant in road construction will help to reduce the disposal problem of this waste and also will help to reduce the problem of scarcity of CSM. Lime and fibre were also added to the pond ash at various percentages to improve the suitability of this type of mix as subbase material. The optimum service life of pavement is studied with the help of numerical modelling and the cost benefit is also presented in the current study. The study reveals that stabilisation of the coal ash with 2% lime may produce an optimal material and, even though a greater thickness may be required to deliver the same pavement performance, direct cost savings of around 10% may be achieved in addition to less easily quantifiable environmental benefits. Design charts are provided to exploit the findings
Vote buying or (political) business (cycles) as usual?
We study the short-run effect of elections on monetary aggregates in a sample of 85 low and middle income democracies (1975-2009). We find an increase in the growth rate of M1 during election months of about one tenth of a standard deviation. A similar effect can neither be detected in established OECD democracies nor in other months. The effect is larger in democracies with many poor and uneducated voters, and in Sub-Saharan Africa, Latin America, and in East-Asia and the Pacific. We argue that the election month monetary expansion is related to systemic vote buying which requires significant amounts of cash to be disbursed right before elections. The finely timed increase in M1 is consistent with this; is inconsistent with a monetary cycle aimed at creating an election time boom; and it cannot be, fully, accounted for by alternative explanations
Planck intermediate results I : Further validation of new Planck clusters with XMM-Newton
Peer reviewe
Genome-wide autozygosity is associated with lower general cognitive ability
Inbreeding depression refers to lower fitness among offspring of genetic relatives. This reduced fitness is caused by the inheritance of two identical chromosomal segments (autozygosity) across the genome, which may expose the effects of (partially) recessive deleterious mutations. Even among outbred populations, autozygosity can occur to varying degrees due to cryptic relatedness between parents. Using dense genome-wide single-nucleotide polymorphism (SNP) data, we examined the degree to which autozygosity associated with measured cognitive ability in an unselected sample of 4854 participants of European ancestry. We used runs of homozygosity-multiple homozygous SNPs in a row-to estimate autozygous tracts across the genome. We found that increased levels of autozygosity predicted lower general cognitive ability, and estimate a drop of 0.6 s.d. among the offspring of first cousins (P=0.003-0.02 depending on the model). This effect came predominantly from long and rare autozygous tracts, which theory predicts as more likely to be deleterious than short and common tracts. Association mapping of autozygous tracts did not reveal any specific regions that were predictive beyond chance after correcting for multiple testing genome wide. The observed effect size is consistent with studies of cognitive decline among offspring of known consanguineous relationships. These findings suggest a role for multiple recessive or partially recessive alleles in general cognitive ability, and that alleles decreasing general cognitive ability have been selected against over evolutionary time.Molecular Psychiatry advance online publication, 22 September 2015; doi:10.1038/mp.2015.120
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