We present and apply a novel scheme for studying photon– and pion–nucleon scattering beyond the threshold region. Partial-wave amplitudes for the
γN and
πN states are obtained by an analytic ...extrapolation of subthreshold reaction amplitudes computed in chiral perturbation theory, where the constraints set by electromagnetic-gauge invariance, causality and unitarity are used to stabilize the extrapolation. Based on the chiral Lagrangian we recover the empirical
s- and
p-wave amplitudes up to energies
s
≃
1300
MeV
in terms of the parameters relevant at order
Q
3
.
The extracellular matrix molecule agrin mediates the motor neuron induced accumulation of acetylcholine receptors (AChR) at the neuromuscular junction. Agrin is also present in the CNS. However, ...while its spatiotemporal pattern of expression is consistent with a function in neuron-neuron synapse formation, it also suggests a role for agrin in other aspects of neural tissue morphogenesis. Here we review the data supporting these synaptic and non-synaptic functions of agrin in the CNS. The results of studies aimed at identifying a neuronal receptor for agrin (NRA) and its associated signal transduction pathways are examined. Possible roles for agrin in the etiology of diseases affecting the brain are also discussed.
We study the chiral expansion of meson masses and decay constants using a chiral Lagrangian that was constructed previously based on the hadrogenesis conjecture. The one-loop self-energies of the ...Goldstone bosons and vector mesons are evaluated. It is illustrated that a order-by-order renormalizable effective field theory arises once specific conditions on the low-energy constants are imposed. For the case where the hadrogenesis mass gap scale ΛHG is substantially larger than the chiral symmetry breaking scale Λχ a partial summation scheme is required. All terms proportional to (M/Λχ)n can be summed by a suitable renormalization, where M is the chiral and large-Nc limit of the vector meson masses in QCD. The size of loop effects from vector meson degrees of freedom is illustrated for physical quark masses. Naturally sized effects are observed that have significant impact on the chiral structure of low-energy QCD with three light flavors.
•Acceptance factors were investigated with an extended technology acceptance model.•Social and individual factors, as well as system characteristics determine user acceptance.•User acceptance is an ...important driver for the widespread adoption of autonomous driving.
Autonomous driving is believed to provide numerous benefits for individuals and society, including increased road safety, reduced traffic congestion, and an improved ecological footprint. However, many barriers still hinder the widespread acceptance of autonomous vehicles. Research has proposed governmental policy strategies to accelerate the diffusion of autonomous driving, but less is known about end-user perceptions of this innovative technology. First, we employ a qualitative research design to identify the elements attributed to individual acceptance of autonomous driving. Furthermore, we organize a research model based on the technology acceptance model, validated with an online survey of 316 participants. The findings reveal how social influence, system characteristics, and individual factors determine individual acceptance of autonomous driving. The research helps to strengthen the existing body of knowledge by highlighting individual perceptions, with implications for practitioners.
We perform an analysis of Lattice QCD data on baryon octet and decuplet masses based on the chiral SU(3) Lagrangian. Low-energy constants (LEC) are adjusted to describe baryon masses from a large set ...of CLS ensembles, where finite-box and discretization effects are considered. The set is successfully compared against previous Lattice QCD data from ensembles generated with distinct QCD actions by the ETMC, QCDSF-UKQCD and HSC groups. Discretization effects are modelled by the use of action and lattice-scale dependent leading orders LEC, where uniform values are imposed in the limit of vanishing lattice scales. From the CLS data set we extract a pion-nucleon sigma term,
σ
π
N
=
58.7
(
1.2
)
MeV, compatible with its empirical value.
A possible direct effect of guanine nucleotide binding (G) proteins on calcium channels was examined in membrane patches excised from guinea pig cardiac myocytes and bovine cardiac sarcolemmal ...vesicles incorporated into planar lipid bilayers. The guanosine triphosphate analog, GTP$_{\gamma}$S, prolonged the survival of excised calcium channels independently of the presence of adenosine 3$^{\prime}$,5$^{\prime}$-monophosphate (cAMP), adenosine triphosphate, cAMP-activated protein kinase, and the protein kinase C activator tetradecanoyl phorbol acetate. A specific G protein, activated G$_{\text{s}}$, or its $\alpha $ subunit, purified from the plasma membranes of human erythrocytes, prolonged the survival of excised channels and stimulated the activity of incorporated channels. Thus, in addition to regulating calcium channels indirectly through activation of cytoplasmic kinases, G proteins can regulate calcium channels directly. Since they also directly regulate a subset of potassium channels, G proteins are now known to directly gate two classes of membrane ion channels.
Previous studies have found evidence that terrorism negatively impacted tourism in individual countries, but studies with larger number of countries have found less evidence for this negative ...linkage. The Caribbean tourist area provides an excellent region for a more nuanced analysis of the effects of terrorist on tourist visits. Evidence from analyses of selected Caribbean countries that rely on tourism indicated that terrorism did not affect tourist visits before the twenty-first century. After 9/11, however, there were indications that territories suffering from terrorism had reductions in visits by tourists. This significant event did influence tourist visits to the Western Hemisphere in the aftermath of this major terrorist event. There were also indications that foreign investment, which is linked to the tourism sector, was negatively affected after 9/11. In at least some cases there are regional effects on tourism from terrorist attacks.
ABSTRACT
We report on the determination of electron densities, and their impact on the outflow masses and rates, measured in the central few hundred parsecs of 11 local luminous active galaxies. We ...show that the peak of the integrated line emission in the active galactic nuclei (AGN) is significantly offset from the systemic velocity as traced by the stellar absorption features, indicating that the profiles are dominated by outflow. In contrast, matched inactive galaxies are characterized by a systemic peak and weaker outflow wing. We present three independent estimates of the electron density in these AGN, discussing the merits of the different methods. The electron density derived from the S ii doublet is significantly lower than that found with a method developed in the last decade using auroral and transauroral lines, as well as a recently introduced method based on the ionization parameter. The reason is that, for gas photoionized by an AGN, much of the S ii emission arises in an extended partially ionized zone where the implicit assumption that the electron density traces the hydrogen density is invalid. We propose ways to deal with this situation and we derive the associated outflow rates for ionized gas, which are in the range 0.001–0.5 M⊙ yr−1 for our AGN sample. We compare these outflow rates to the relation between $\dot{M}_{\rm out}$ and LAGN in the literature, and argue that it may need to be modified and rescaled towards lower mass outflow rates.
Bistability in Atomic-Scale Antiferromagnets Loth, Sebastian; Baumann, Susanne; Lutz, Christopher P. ...
Science (American Association for the Advancement of Science),
01/2012, Letnik:
335, Številka:
6065
Journal Article
Recenzirano
Control of magnetism on the atomic scale is becoming essential as data storage devices are miniaturized. We show that antiferromagnetic nanostructures, composed of just a few Fe atoms on a surface, ...exhibit two magnetic states, the Néel states, that are stable for hours at low temperature. For the smallest structures, we observed transitions between Néel states due to quantum tunneling of magnetization. We sensed the magnetic states of the designed structures using spin-polarized tunneling and switched between them electrically with nanosecond speed. Tailoring the properties of neighboring antiferromagnetic nanostructures enables a low-temperature demonstration of dense nonvolatile storage of information.
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