1,329 research outputs found
The Gluon Propagator in Momentum Space
We give preliminary numerical results for the gluon propagator evaluated both
in coordinate and momentum space on a 16^3X40 quenched lattice at beta=6.0. Our
findings are compared with earlier results in the literature at zero momentum.
In addition, by considering nonzero momenta we attempt to extract the form of
the propagator and compare it to continuum predictions formulated by Gribov and
others. latex, file espcrc2.sty needed (appended at the end: search for
espcrc2.sty).Comment: 4 page
The Behavioral Mechanisms Behind Feedback – A Preliminary Model for Quantifying Cause-Effect Relationships
The ubiquity of information technology makes it possible to provide individuals with personalized, context-specific, and timely feedback at low marginal cost. This allows for highly scalable behavioral interventions that can support behavior change even for frequent, habitual, and incidental behaviors. Despite the well-documented potential of feedback interventions in improving personal and societal outcomes, the associated theoretical insights – in particular for real-time feedback on everyday behaviors – are sparse. To this end, this research-in-progress paper proposes a conceptual model to formalize cause-effect relationships between feedback interventions, the antecedents of behavior, and resulting behavioral changes by integrating important concepts from feedback intervention theory and other behavioral theories. Moreover, this paper outlines the planned validation of the model and research hypotheses with an empirical field study. Ultimately, the results are expected to inform the development of (future) Information Systems for behavior change by holistically explaining behavioral mechanisms associated with feedback interventions
Three-Nucleon Force and the -Mechanism for Pion Production and Pion Absorption
The description of the three-nucleon system in terms of nucleon and
degrees of freedom is extended to allow for explicit pion production
(absorption) from single dynamic de-excitation (excitation) processes.
This mechanism yields an energy dependent effective three-body hamiltonean. The
Faddeev equations for the trinucleon bound state are solved with a force model
that has already been tested in the two-nucleon system above pion-production
threshold. The binding energy and other bound state properties are calculated.
The contribution to the effective three-nucleon force arising from the pionic
degrees of freedom is evaluated. The validity of previous coupled-channel
calculations with explicit but stable isobar components in the
wavefunction is studied.Comment: 23 pages in Revtex 3.0, 9 figures (not included, available as
postscript files upon request), CEBAF-TH-93-0
The pion-three-nucleon problem with two-cluster connected-kernel equations
It is found that the coupled piNNN-NNN system breaks into fragments in a
nontrivial way. Assuming the particles as distinguishable, there are indeed
four modes of fragmentation into two clusters, while in the standard three-body
problem there are three possible two-cluster partitions and conversely the
four-body problem has seven different possibilities. It is shown how to
formulate the pion-three-nucleon collision problem through the
integral-equation approach by taking into account the proper fragmentation of
the system. The final result does not depend on the assumption of separability
of the two-body t-matrices. Then, the quasiparticle method a' la
Grassberger-Sandhas is applied and effective two-cluster connected-kernel
equations are obtained. The corresponding bound-state problem is also
formulated, and the resulting homogeneous equation provides a new approach
which generalizes the commonly used techniques to describe the three-nucleon
bound-state problem, where the meson degrees of freedom are usually suppressed.Comment: 20 pages, REVTeX, with 3 COLOR figures (PostScript
Persistent detwinning of iron pnictides by small magnetic fields
Our comprehensive study on EuFeAs reveals a dramatic reduction of
magnetic detwinning fields compared to other AFeAs (A = Ba, Sr, Ca)
iron pnictides by indirect magneto-elastic coupling of the Eu ions. We
find that only 0.1T are sufficient for persistent detwinning below the local
Eu ordering; above = 19K, higher fields are necessary.
Even after the field is switched off, a significant imbalance of twin domains
remains constant up to the structural and electronic phase transition (190K).
This persistent detwinning provides the unique possibility to study the low
temperature electronic in-plane anisotropy of iron pnictides without applying
any symmetrybreaking external force.Comment: accepted by Physical Review Letter
Do biometric parameters improve the quality of optic nerve head measurements with spectral domain optical coherence tomography?
Funding Information: A part of the study data have been presented as a free paper oral presentation ‘ Clinical quality assessment of optic nerve head measurements with spectral domain optical coherence tomography—preliminary results’ in 118. Congress of the DOG (German Society of Ophthalmology) 2020. Publisher Copyright: © 2022, The Author(s).Background: Spectral domain optical coherence tomography (SD-OCT) is a widely applied non-invasive technique for evaluating optic nerve head parameters. The aim of this study was to evaluate the impact of biometric parameters such as the spherical equivalent (SE) and the anterior corneal curvature (ACC) on the peripapillary retinal nerve fiber layer (pRNFL), Bruch’s membrane opening (BMO), and the minimum rim width (MRW) measurements performed by spectral domain optical coherence tomography (SD-OCT) in glaucomatous and healthy eyes. Methods: In this cross-sectional, case–control prospective pilot study, the glaucoma group consisted of 50 patients with previously diagnosed and treated glaucoma and one healthy group of 50 subjects. Two consecutive examinations of pRNFL, BMO, and MRW with SD-OCT for every patient were performed without ACC and objective refraction (imaging 1) and with them (imaging 2). Results: The interclass correlation coefficient (ICC) reflected high agreement between imaging 1 and imaging 2 in both groups. The ICC in the glaucoma and healthy groups for pRNFL (0.99 vs. 0.98), BMO (0.95 vs. 0.97), and MRW (1.0 vs. 1.0) was comparable. Conclusions: Our preliminary data from a small number of eyes showed that the measurements of pRNFL, MRW, and BMO reflected high agreement between both imaging techniques with ACC and objective refraction and without these parameters in subjects with a refractive error up to ± 6.0 diopters. Further studies with participants with higher refractive error are necessary to evaluate the impact of biometric parameters such as SE and ACC on measurements with SD-OCT.publishersversionPeer reviewe
Reduction of Campylobacter jejuni in Broiler Chicken by Successive Application of Group II and Group III Phages
Background Bacteriophage treatment is a promising tool to reduce Campylobacter
in chickens. Several studies have been published where group II or group III
phages were successfully applied. However, these two groups of phages are
different regarding their host ranges and host cell receptors. Therefore, a
concerted activity of group II and group III phages might enhance the efficacy
of a treatment and decrease the number of resistant bacteria. Results In this
study we have compared the lytic properties of some group II and group III
phages and analysed the suitability of various phages for a reduction of C.
jejuni in broiler chickens. We show that group II and group III phages exhibit
different kinetics of infection. Two group III and one group II phage were
selected for animal experiments and administered in different combinations to
three groups of chickens, each containing ten birds. While group III phage
CP14 alone reduced Campylobacter counts by more than 1 log10 unit, the
concomitant administration of a second group III phage (CP81) did not yield
any reduction, probably due to the development of resistance induced by this
phage. One group of chickens received phage CP14 and, 24 hours later, group II
phage CP68. In this group of animals, Campylobacter counts were reduced by
more than 3 log10 units. Conclusion The experiments illustrated that
Campylobacter phage cocktails have to be carefully composed to achieve the
best results
Stem and progenitor cell division kinetics during postnatal mouse mammary gland development.
The cycling properties of mammary stem and progenitor cells is not well understood. To determine the division properties of these cells, we administered synthetic nucleosides for varying periods of time to mice at different stages of postnatal development and monitored the rate of uptake of these nucleosides in the different mammary cell compartments. Here we show that most cell division in the adult virgin gland is restricted to the oestrogen receptor-expressing luminal cell lineage. Our data also demonstrate that the oestrogen receptor-expressing, milk and basal cell subpopulations have telomere lengths and cell division kinetics that are not compatible with these cells being hierarchically organized; instead, our data indicate that in the adult homeostatic gland, each cell type is largely maintained by its own restricted progenitors. We also observe that transplantable stem cells are largely quiescent during oestrus, but are cycling during dioestrus when progesterone levels are high.We thank the members of Stingl lab, Doug Winton, Jason Carroll, Robert Clarke, Phil Jones and Hamid Raza Ali for scientific discussions. We thank the core facilities at the Cancer Research UK-CI for enabling experiments. In particular, Loic Tauzin, Nina Lane and Mateuz Strzelecki for assistance with cell sorting; the Biological Resources Unit for animal husbandry; and Histopathology staff, in particular Leigh-Anne McDuffus and Cara Walters. J. Stingl’s laboratory acknowledges the support of The University of Cambridge, Cancer Research UK (core grant number C14303/A17197) and Hutchison Whampoa Limited. M.A. Blasco’s laboratory is funded by the Spanish Ministry of Economy and Competitiveness Project SAF2013-45111RETOS, the European Union FP7 Project EUROBATS, the European Research Council (ERC) Project TEL STEM CELL (GA#232854), the Regional Government of Madrid project 2+2 ReCaRe, the AXA Research Fund and the Fundación Botín.This is the final version of the article. It was first available from Nature via http://dx.doi.org/10.1038/ncomms948
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