3,221 research outputs found
On the quest for unification - simplicity and antisimplicity
The road towards unification of elementary interactions is thought to start
on the solid ground of a universal local gauge principle. I discuss the
different types of bosonic gauge symmetries in gravitational and
nongravitational (standard model) interactions and their extensions both
fermionic, bosonic and with respect to space-time dimensions. The apparently
paradoxical size and nature of the cosmological constant is sketched, which at
first sight does not readily yield a clue as to the envelopping symmetry
structure of a unified theory. Nevertheless a tentative outlook is given
encouraging to proceed on this road.Comment: 29 pages, 4 figure
Vascular Pathophysiology in Response to Increased Heart Rate
This review summarizes the current literature and the open questions regarding the physiology and pathophysiology of the mechanical effects of heart rate on the vessel wall and the associated molecular signaling that may have implications for patient care. Epidemiological evidence shows that resting heart rate is associated with cardiovascular morbidity and mortality in the general population and in patients with cardiovascular disease. As a consequence, increased resting heart rate has emerged as an independent risk factor both in primary prevention and in patients with hypertension, coronary artery disease, and myocardial infarction. Experimental and clinical data suggest that sustained elevation of heart rate—independent of the underlying trigger—contributes to the pathogenesis of vascular disease. In animal studies, accelerated heart rate is associated with cellular signaling events leading to vascular oxidative stress, endothelial dysfunction, and acceleration of atherogenesis. The underlying mechanisms are only partially understood and appear to involve alterations of mechanic properties such as reduction of vascular compliance. Clinical studies reported a positive correlation between increased resting heart rate and circulating markers of inflammation. In patients with coronary heart disease, increased resting heart rate may influence the clinical course of atherosclerotic disease by facilitation of plaque disruption and progression of coronary atherosclerosis. While a benefit of pharmacological or interventional heart rate reduction on different vascular outcomes was observed in experimental studies, prospective clinical data are limited, and prospective evidence determining whether modulation of heart rate can reduce cardiovascular events in different patient populations is needed
The 10th Biennial Hatter Cardiovascular Institute workshop: cellular protection—evaluating new directions in the setting of myocardial infarction, ischaemic stroke, and cardio-oncology
Due to its poor capacity for regeneration, the heart is particularly sensitive to the loss of contractile cardiomyocytes. The onslaught of damage caused by ischaemia and reperfusion, occurring during an acute myocardial infarction and the subsequent reperfusion therapy, can wipe out upwards of a billion cardiomyocytes. A similar program of cell death can cause the irreversible loss of neurons in ischaemic stroke. Similar pathways of lethal cell injury can contribute to other pathologies such as left ventricular dysfunction and heart failure caused by cancer therapy. Consequently, strategies designed to protect the heart from lethal cell injury have the potential to be applicable across all three pathologies. The investigators meeting at the 10th Hatter Cardiovascular Institute workshop examined the parallels between ST-segment elevation myocardial infarction (STEMI), ischaemic stroke, and other pathologies that cause the loss of cardiomyocytes including cancer therapeutic cardiotoxicity. They examined the prospects for protection by remote ischaemic conditioning (RIC) in each scenario, and evaluated impasses and novel opportunities for cellular protection, with the future landscape for RIC in the clinical setting to be determined by the outcome of the large ERIC-PPCI/CONDI2 study. It was agreed that the way forward must include measures to improve experimental methodologies, such that they better reflect the clinical scenario and to judiciously select combinations of therapies targeting specific pathways of cellular death and injury
Upper bound on the scale of Majorana-neutrino mass generation
We derive a model-independent upper bound on the scale of Majorana-neutrino
mass generation. The upper bound is , where GeV is the weak scale and is the Majorana neutrino mass. For
neutrino masses implied by neutrino oscillation experiments, all but one of
these bounds are less than the Planck scale, and they are all within a few
orders of magnitude of the grand-unification scale.Comment: 6 pages, 3 figures; REVTeX; published versio
New fermions and a vector-like third generation in models
We study two 3-3-1 models with i) five (four) charge 2/3 () quarks and,
ii) four (five) charge 2/3 () quarks and a vector-like third generation.
Possibilities beyond these models are also briefly considered.Comment: 32 pages, Revtex 3.0, no figure
One-loop chiral amplitudes of Moller scattering process
The high energy amplitudes of the large angles Moller scattering are
calculated in frame of chiral basis in Born and 1-loop QED level. Taking into
account as well the contribution from emission of soft real photons the compact
relations free from infrared divergences are obtained. The expressions for
separate chiral amplitudes contribution to the cross section are in agreement
with renormalization group predictions.Comment: 15 pages, 3 figure
Photo- and Electroproduction of Eta Mesons
Eta photo- and electroproduction off the nucleon is investigated in an
effective lagrangian approach that contains Born terms and both vector meson
and nucleon resonance contributions. In particular, we review and develop the
formalism for coincidence experiments with polarization degrees of freedom. The
different response functions appearing in single and double polarization
experiments have been studied. We will present calculations for structure
functions and kinematical conditions that are most sensitive to details of the
lagrangian, in particular with regard to contributions of nucleon resonances
beyond the dominant (1535) resonance.Comment: 24 pages RevTeX/LaTeX2.09, NFSS1, 13 figures (in separate file
(tar,gzip and uue)), accepted for publication in Z. Phys.
Selectron production at an e-e- linear collider with transversely polarized beams
We study selectron production at an e-e- linear collider. With the help of
transverse beam polarizations, we define CP sensitive observables in the
production process e- e- --> selectron_L selectron_R. This process proceeds via
t-channel and u-channel exchange of neutralinos, and is sensitive to CP
violation in the neutralino sector. We present numerical results and estimate
the significances to which the CP sensitive observables can be measured.Comment: 14 page
The Noncommutative Standard Model and Forbidden Decays
In this contribution we discuss the Noncommutative Standard Model and the
associated Standard Model-forbidden decays that can possibly serve as an
experimental signature of space-time noncommutativity.Comment: 15 pages, 1 figure, Invited talk at 9th Adriatic Meeting and Central
European Symposia on Particle Physics and The Universe, Dubrovnik, Croatia,
4-14 Sep 200
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