1,959 research outputs found
An interacting quark-diquark model of baryons
A simple quark-diquark model of baryons with direct and exchange interactions
is constructed. Spectrum and form factors are calculated and compared with
experimental data. Advantages and disadvantages of the model are discussed.Comment: 13 pages, 3 eps-figures, accepted by Phys.Rev. C Rapid Communication
Die wese van godsdienssin - ân empiriese studie
In this article the following issues concerning the essence of religiosity are considered: faith, trust, decision making, knowledge of principles, commitment, direction, hope, peace, meaning and security. The respondents used in this study were politicians, businessmen and teacher educators from all sectors and regions of South Africa. Higher order factor analysis and item analysis were used to evaluate the validity and reliability of the questionnaire. Subsequently differential differences were investigated by applying Hotelling's T-square test followed by the Student t-test as well as Multivariate Analysis of Variance (ANOVA) and Scheffe. Significant differences in the degree of religiosity were found between language and religious groups, as well as between respondents with different educational qualifications and between those living in urban and rural areas. Ministers of religion should note that it is essential to guide believers to a greater commitment and to the religious seeking of meaning and peace. The correct knowledge of and insight into the essence of religiosity will lead to attaining this goal
Soft-core meson-baryon interactions. II. and scattering
The potential includes the t-channel exchanges of the scalar-mesons
and f_0, vector-meson , tensor-mesons f_2 and f_2' and the
Pomeron as well as the s- and u-channel exchanges of the nucleon N and the
resonances , Roper and S_{11}. These resonances are not generated
dynamically. We consider them as, at least partially, genuine three-quark
states and we treat them in the same way as the nucleon. The latter two
resonances were needed to find the proper behavior of the phase shifts at
higher energies in the corresponding partial waves. The soft-core -model
gives an excellent fit to the empirical S- and P-wave phase shifts up
to T_{lab}=600 MeV. Also the scattering lengths have been reproduced well and
the soft-pion theorems for low-energy scattering are satisfied. The
soft-core model for the interaction is an SU_f(3)-extension of the
soft-core -model. The potential includes the t-channel exchanges
of the scalar-mesons a_0, and f_0, vector-mesons , and
, tensor-mesons a_2, f_2 and f_2' and the Pomeron as well as u-channel
exchanges of the hyperons and . The fit to the empirical S-, P- and D-wave phase shifts up to T_{lab}=600 MeV is reasonable and
certainly reflects the present state of the art. Since the various
phase shift analyses are not very consistent, also scattering observables are
compared with the soft-core -model. A good agreement for the total and
differential cross sections as well as the polarizations is found.Comment: 24 pages, 20 PostScript figures, revtex4, submitted to Phys. Rev.
Nucleon-Nucleon interaction, charge symmetry breaking and renormalization
We study the interplay between charge symmetry breaking and renormalization
in the NN system for s-waves. We find a set of universality relations which
disentangle explicitly the known long distance dynamics from low energy
parameters and extend them to the Coulomb case. We analyze within such an
approach the One-Boson-Exchange potential and the theoretical conditions which
allow to relate the proton-neutron, proton-proton and neutron-neutron
scattering observables without the introduction of extra new parameters and
providing good phenomenological success.Comment: 15 pages, 6 figure
Masculine generic pronouns as a gender cue in generic statements
An eye-tracking experiment was conducted with speakers of Dutch (N = 84, 36 male), a language that falls between grammatical and natural-gender languages. We tested whether a masculine generic pronoun causes a male bias when used in generic statementsâthat is, in the absence of a specific referent. We tested two types of generic statements by varying conceptual number, hypothesizing that the pronoun zijn âhisâ was more likely to cause a male bias with a conceptually singular than a conceptually plural ante-cedent (e.g., Someone (conceptually singular)/Everyone (conceptually plural) with perfect pitch can tune his instrument quickly). We found male participants to exhibit a male bias but with the conceptually singular antecedent only. Female participants showed no signs of a male bias. The results show that the generically intended masculine pronoun zijn âhisâ leads to a male bias in conceptually singular generic contexts but that this further depends on participant gender
Pertinent Dirac structure for QCD sum rules of meson-baryon coupling constants
Using general baryon interpolating fields for
without derivative, we study QCD sum rules for meson-baryon couplings and their
dependence on Dirac structures for the two-point correlation function with a
meson i\int d^4x e^{iqx} \bra 0|{\rm T}[J_B(x)\bar{J}_B(0)] |{\cal M}(p)\ket.
Three distinct Dirac structures are compared: ,
i\gamma_5\fslash{p}, and structures.
From the dependence of the OPE on general baryon interpolating fields, we
propose criteria for choosing an appropriate Dirac structure for the coupling
sum rules. The sum rules satisfy the
criteria while the sum rules beyond the chiral limit do not. For
the i\gamma_5\fslash{p} sum rules, the large continuum contributions prohibit
reliable prediction for the couplings. Thus, the structure seems pertinent for realistic predictions. In the SU(3) limit,
we identify the OPE terms responsible for the ratio. We then study the
dependence of the ratio on the baryon interpolating fields. We conclude the
ratio for appropriate choice of the interpolating fields.Comment: To be published in Phys.Rev.C ; 21 pages,8 figures, revtex ;
references are adde
Contaminant-related suppression of delayed-type hypersensitivity and antibody responses in harbor seals fed herring from the Baltic Sea.
Recent mass mortalities among several marine mammal populations have led to speculation about increased susceptibility to viral infections as a result of contaminant-induced immunosuppression. In a 2.5-year study, we fed herring from either the relatively uncontaminated Atlantic Ocean or the contaminated Baltic Sea to two groups of captive harbor seals and monitored immune function in the seals. Seals fed the contaminated fish were less able to mount a specific immunological response to ovalbumin, as measured by in vivo delayed-type hypersensitivity (DTH) reactions and antibody responses. The skin reaction to this protein antigen was characterized by the appearance of mononuclear cells which peaked at 24 hr after intradermal administration, characteristic of DTH reactions in other animals studied. These DTH responses correlated well with in vitro tests of T-lymphocyte function, implicating this cell type in the reaction. Aryl-hydrocarbon (Ah) receptor-dependent toxic equivalent (TEQ) profiles in blubber biopsies taken from the seals implicated polychlorinated biphenyls rather than dioxins or furans in the observed immunosuppression. Marine mammal populations currently inhabiting polluted coastal environments in Europe and North America may therefore have an increased susceptibility to infections, and pollution may have played a role in recent virus-induced mass mortalities
Quantification of ferritin-bound iron in murine samples for Alzheimer's disease studies using species-specific isotope dilution mass spectrometry
Acknowledgments The project ReMiND 15HLT02 has received funding from the EMPIR programme co-financed by the Participating States and from the European Union's Horizon 2020 research and innovation programme. The authors gratefully thank Christoph Baumgartinger for his support with sample preparation as well as one independent referee for highly constructive comments.Peer reviewedPublisher PD
Soft two-meson-exchange nucleon-nucleon potentials. II. One-pair and two-pair diagrams
Two-meson-exchange nucleon-nucleon potentials are derived where either one or
both nucleons contains a pair vertex. Physically, the meson-pair vertices are
meant to describe in an effective way (part of) the effects of heavy-meson
exchange and meson-nucleon resonances. {}From the point of view of ``duality,''
these two kinds of contribution are roughly equivalent. The various
possibilities for meson pairs coupling to the nucleon are inspired by the
chiral-invariant phenomenological Lagrangians that have appeared in the
literature. The coupling constants are fixed using the linear model.
We show that the inclusion of these two-meson exchanges gives a significant
improvement over a potential model including only the standard one-boson
exchanges.Comment: 21 pages RevTeX, 7 postscript figures; revised version as to appear
in Phys. Rev.
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