53 research outputs found
Proton Decay from Excited States in Spherical Nuclei
Based on a single particle model which describes the time evolution of the
wave function during tunneling across a one dimensional potential barrier we
study the proton decay of Pb from excited states with non-vanishing
angular momentum . Several quantities of interest in this process like
the decay rate , the period of oscillation , the transient
time , the tunneling time and the average value of the proton
packet position are computed and compared with the WKB results.Comment: 12 pages, 4 figure
Decay Rate of Triaxially-Deformed Proton Emitters
The decay rate of a triaxially-deformed proton emitter is calculated in a
particle-rotor model, which is based on a deformed Woods-Saxon potential and
includes a deformed spin-orbit interaction. The wave function of the
ground state of the deformed proton emitter Ho is obtained
in the adiabatic limit, and a Green's function technique is used to calculate
the decay rate and branching ratio to the first excited 2 state of the
daughter nucleus. Only for values of the triaxial angle
is good agreement obtained for both the total decay rate and the 2
branching ratio.Comment: 19 pages, 4 figure
Time-dependent properties of proton decay from crossing single-particle metastable states in deformed nuclei
A dynamical study of the decay of a metastable state by quantum tunneling
through an anisotropic, non separable, two-dimensional potential barrier is
performed by the numerical solution of the time-dependent Schrodinger equation.
Initial quasi- stationary proton states are chosen in the framework of a
deformed Woods-Saxon single-particle model. The decay of two sets of states
corresponding to true and quasi levels-crossing is studied and the evolution of
their decay properties as a function of nuclear deformation is calculated
around the crossing point. The results show that the investigation of the
proton decay from metastable states in deformed nuclei can unambiguously
distinguish between the two types of crossing and determine the structure of
the nuclear states involved.Comment: 15 pages, 9 figures, submitted to Phys. Rev.
Role of dynamical particle-vibration coupling in reconciliation of the puzzle for spherical proton emitters
It has been observed that decay rate for proton emission from
single particle state is systematically quenched compared with the prediction
of a one dimensional potential model although the same model successfully
accounts for measured decay rates from and states. We
reconcile this discrepancy by solving coupled-channels equations, taking into
account couplings between the proton motion and vibrational excitations of a
daughter nucleus. We apply the formalism to proton emitting nuclei
Re to show that there is a certain range of parameter set of the
excitation energy and the dynamical deformation parameter for the quadrupole
phonon excitation which reproduces simultaneously the experimental decay rates
from the 2, 3 and 1 states in these nuclei.Comment: RevTex, 12 pages, 4 eps figure
Specific features of microheterogeneous plasma produced by irradiation of a polymer aerogel target with an intense 500-ps-long laser pulse
Effect of combination antihypertensive therapy, including renin-angiotensin-aldosterone system inhibitors, on oxidative stress and arterial remodeling in hypertensive patients with heart failure with preserved ejection fraction
Aim. To study the effect of triple combination therapy on oxidative stress and arterial remodeling in hypertensive patients with heart failure with preserved ejection fraction (HFpEF).Material and methods. The study involved 76 people with diagnosed HFpEF. After a comprehensive examination, patients were randomized into two equal groups: first group â patients who received perindopril 10 mg, indapamide 2,5mg and amlodipine 5 mg; second â patients who received losartan 100 mg, indapamide 2,5 mg, amlodipine 5 mg. Before and 16 weeks after the therapy initiation, cardiac ultrasound, assessment of endothelial function with estimating endothelium-dependent vasodilation, assessment of vascular stiffness by photoplethysmography and compression oscillometry were carried out. The plasma concentration of oxidative stress marker 8-isoprostane was studied.Results. During the follow-up period, a significant improvement in endothelial function was noted: in the first group â from 8,1% to 11,4% (p=0,001), in the second â from 5,8% to 8,3% (p=0,0007). In both groups, there was an improvement in microvessel elasticity: a significant decrease in specific peripheral vascular resistance, as well as a significant decrease in total peripheral resistance in the first group (p<0,002) and a tendency to decrease in the second one (p>0,05). There was a significant increase in the stiffness of the aorta and muscular arteries in both groupsŃ In the first group, a stiffness index decreased from 10,38 m/s to 8,33 m/s (p<0,0001), in the second â from 10,6 m/s to 9,3 m/s (p<0,01). In addition, resistance index in the first group decreased from 71,5% to 60% (p<0,0001), while in the second â from 68% to 60% (p=0,006). Also, both groups showed a significant decrease in the left atrial diastolic dimension and the left atrial volume index. A decrease in the 8-isoprostane plasma levels was noted, which indicates a decrease in oxidative stress.Conclusion. Oxidative stress, which develops due to chronic systemic inflammation, plays a key role in the pathogenesis of HFpEF. The results obtained show an improved endothelial function as a result of decrease in oxidative stress, which is accompanied by an improvement in vessel wall elasticity, thereby slowing down the heart failure progression
- âŠ