Metastabilnost α-stabilnih jezgri bogatih neutroni!vla

Cluster radioactivities of nuclei far from beta-stability line in the neutron-rich region, where a-decay is not allowed, have been systematically studied within analytical superasymmetric fission model. Input mass tables calculated by various authors were used to determine the released energy. Half-lives shorter than 1030 seconds have been estimated for very neutron-rich parent nuclei with atomic numbers form 57 to 86. The emitted clusters are also proton-deficient nuclei, as for example 22O, 46S, 50Ar, 76Fe, 78Ni, etc.Sistematski je istraživana radioaktivnost atomskih jezgri s emisijom nukleonskih grozdova u području bogatom neutronima izvan linije beta stabilnosti, koristeći analitički supersimetrijski fisijski model. U određivanju oslobođene energije upotrebljavane su masene tablice različitih autora. Za jezgre bogate neutronima s atomskim brojevima između 57 i 86 procijenjena su vremena poluraspada na manje od 10 30 s. Emitirani grozdovi su također jezgre siromašne protonima, kao na primjer 2 20, 4 6S, 50Ar, 7 6Fe, 7 8Ni itd

Metastabilnost α-stabilnih jezgri bogatih neutroni!vla

Cluster radioactivities of nuclei far from beta-stability line in the neutron-rich region, where a-decay is not allowed, have been systematically studied within analytical superasymmetric fission model. Input mass tables calculated by various authors were used to determine the released energy. Half-lives shorter than 1030 seconds have been estimated for very neutron-rich parent nuclei with atomic numbers form 57 to 86. The emitted clusters are also proton-deficient nuclei, as for example 22O, 46S, 50Ar, 76Fe, 78Ni, etc.Sistematski je istraživana radioaktivnost atomskih jezgri s emisijom nukleonskih grozdova u području bogatom neutronima izvan linije beta stabilnosti, koristeći analitički supersimetrijski fisijski model. U određivanju oslobođene energije upotrebljavane su masene tablice različitih autora. Za jezgre bogate neutronima s atomskim brojevima između 57 i 86 procijenjena su vremena poluraspada na manje od 10 30 s. Emitirani grozdovi su također jezgre siromašne protonima, kao na primjer 2 20, 4 6S, 50Ar, 7 6Fe, 7 8Ni itd

Stable spatiotemporal solitons in Bessel optical lattices

We investigate the existence and stability of three-dimensional (3D) solitons supported by cylindrical Bessel lattices (BLs) in self-focusing media. If the lattice strength exceeds a threshold value, we show numerically, and using the variational approximation, that the solitons are stable within one or two intervals of values of their norm. In the latter case, the Hamiltonian-vs.-norm diagram has a "swallowtail" shape, with three cuspidal points. The model applies to Bose-Einstein condensates (BECs) and to optical media with saturable nonlinearity, suggesting new ways of making stable 3D BEC solitons and "light bullets" of an arbitrary size.Comment: 9 pages, 4 figures, Phys. Rev. Lett., in pres

Stable topological modes in two-dimensional Ginzburg-Landau models with trapping potentials

Complex Ginzburg-Landau (CGL) models of laser media (with the cubic-quintic nonlinearity) do not contain an effective diffusion term, which makes all vortex solitons unstable in these models. Recently, it has been demonstrated that the addition of a two-dimensional periodic potential, which may be induced by a transverse grating in the laser cavity, to the CGL equation stabilizes compound (four-peak) vortices, but the most fundamental "crater-shaped" vortices (CSVs), alias vortex rings, which are, essentially, squeezed into a single cell of the potential, have not been found before in a stable form. In this work we report families of stable compact CSVs with vorticity S=1 in the CGL model with the external potential of two different types: an axisymmetric parabolic trap, and the periodic potential. In both cases, we identify stability region for the CSVs and for the fundamental solitons (S=0). Those CSVs which are unstable in the axisymmetric potential break up into robust dipoles. All the vortices with S=2 are unstable, splitting into tripoles. Stability regions for the dipoles and tripoles are identified too. The periodic potential cannot stabilize CSVs with S>=2 either; instead, families of stable compact square-shaped quadrupoles are found

Evidence for LineLike Vortex Liquid Phase in Tl2_2Ba2_2CaCu2_2O8_8 Probed by the Josephson Plasma Resonance

We measured the Josephson plasma resonance (JPR) in optimally doped Tl$_2$Ba$_2$CaCu$_2$O$_{8+\delta}$ thin films using terahertz time-domain spectroscopy in transmission. The temperature and magnetic field dependence of the JPR frequency shows that the c-axis correlations of pancake vortices remain intact at the transition from the vortex solid to the liquid phase. In this respect Tl$_2$Ba$_2$CaCu$_2$O$_{8+\delta}$ films, withanisotropy parameter $\gamma\approx 150$, are similar to the less anisotropic YBa$_2$Cu$_3$O$_{7-\delta}$ $(\gamma\approx 8)$ rather than to the most anisotropic Bi$_2$Sr$_2$CaCu$_2$O$_{8+\delta}$ single crystals $\gamma\geq 500$).Comment: Submitted to Physical Review Letter

Stable spinning optical solitons in three dimensions

We introduce spatiotemporal spinning solitons (vortex tori) of the three-dimensional nonlinear Schrodinger equation with focusing cubic and defocusing quintic nonlinearities. The first ever found completely stable spatiotemporal vortex solitons are demonstrated. A general conclusion is that stable spinning solitons are possible as a result of competition between focusing and defocusing nonlinearities.Comment: 4 pages, 6 figures, accepted to Phys. Rev. Let

A new class of glycomimetic drugs to prevent free fatty acid-induced endothelial dysfunction

Background: Carbohydrates play a major role in cell signaling in many biological processes. We have developed a set of glycomimetic drugs that mimic the structure of carbohydrates and represent a novel source of therapeutics for endothelial dysfunction, a key initiating factor in cardiovascular complications. Purpose: Our objective was to determine the protective effects of small molecule glycomimetics against free fatty acid­induced endothelial dysfunction, focusing on nitric oxide (NO) and oxidative stress pathways. Methods: Four glycomimetics were synthesized by the stepwise transformation of 2,5­dihydroxybenzoic acid to a range of 2,5­substituted benzoic acid derivatives, incorporating the key sulfate groups to mimic the interactions of heparan sulfate. Endothelial function was assessed using acetylcholine­induced, endotheliumdependent relaxation in mouse thoracic aortic rings using wire myography. Human umbilical vein endothelial cell (HUVEC) behavior was evaluated in the presence or absence of the free fatty acid, palmitate, with or without glycomimetics (1µM). DAF­2 and H2DCF­DA assays were used to determine nitric oxide (NO) and reactive oxygen species (ROS) production, respectively. Lipid peroxidation colorimetric and antioxidant enzyme activity assays were also carried out. RT­PCR and western blotting were utilized to measure Akt, eNOS, Nrf­2, NQO­1 and HO­1 expression. Results: Ex vivo endothelium­dependent relaxation was significantly improved by the glycomimetics under palmitate­induced oxidative stress. In vitro studies showed that the glycomimetics protected HUVECs against the palmitate­induced oxidative stress and enhanced NO production. We demonstrate that the protective effects of pre­incubation with glycomimetics occurred via upregulation of Akt/eNOS signaling, activation of the Nrf2/ARE pathway, and suppression of ROS­induced lipid peroxidation. Conclusion: We have developed a novel set of small molecule glycomimetics that protect against free fatty acidinduced endothelial dysfunction and thus, represent a new category of therapeutic drugs to target endothelial damage, the first line of defense against cardiovascular disease