Nuclear collective motion with a coherent coupling interaction between quadrupole and octupole modes

A collective Hamiltonian for the rotation-vibration motion of nuclei is considered, in which the axial quadrupole and octupole degrees of freedom are coupled through the centrifugal interaction. The potential of the system depends on the two deformation variables $\beta_2$ and $\beta_3$. The system is considered to oscillate between positive and negative $\beta_3$-values, by rounding an infinite potential core in the $(\beta_2,\beta_3)$-plane with $\beta_2>0$. By assuming a coherent contribution of the quadrupole and octupole oscillation modes in the collective motion, the energy spectrum is derived in an explicit analytic form, providing specific parity shift effects. On this basis several possible ways in the evolution of quadrupole-octupole collectivity are outlined. A particular application of the model to the energy levels and electric transition probabilities in alternating parity spectra of the nuclei $^{150}$Nd, $^{152}$Sm, $^{154}$Gd and $^{156}$Dy is presented.Comment: 25 pages, 13 figures. Accepted in Phys. Rev.

Interaction potential between two axially symmetric nuclei

The simple approach for the evaluation of the interaction potential between two deformed axial-symmetric nuclei is proposed. The potential energy of deformed arbitrary-oriented nuclei is discussed in detail. Properties of entrancechannel potential for fusion reactions 22Ne + 248Cm and 26Mg + 248Cm leading to super-heavy elements are considered

Two-body Photodisintegration of 4^{4}He with Full Final State Interaction

The cross sections of the processes $^4$He($\gamma,p$)$^3$H and $^4$He($\gamma,n$)$^3$He are calculated taking into account the full final state interaction via the Lorentz integral transform (LIT) method. This is the first consistent microscopic calculation beyond the three--body breakup threshold. The results are obtained with a semirealistic central NN potential including also the Coulomb force. The cross sections show a pronounced dipole peak at 27 MeV which lies within the rather broad experimental band. At higher energies, where experimental uncertainties are considerably smaller, one finds a good agreement between theory and experiment. The calculated sum of three-- and four--body photodisintegration cross sections is also listed and is in fair agreement with the data.Comment: 18 pages, 6 figure

Magnetic relaxation in finite two-dimensional nanoparticle ensembles

We study the slow phase of thermally activated magnetic relaxation in finite two-dimensional ensembles of dipolar interacting ferromagnetic nanoparticles whose easy axes of magnetization are perpendicular to the distribution plane. We develop a method to numerically simulate the magnetic relaxation for the case that the smallest heights of the potential barriers between the equilibrium directions of the nanoparticle magnetic moments are much larger than the thermal energy. Within this framework, we analyze in detail the role that the correlations of the nanoparticle magnetic moments and the finite size of the nanoparticle ensemble play in magnetic relaxation.Comment: 21 pages, 4 figure

New limits on di-nucleons decay into invisible channels

Data of the radiochemical experiment [E.L.Fireman, 1978] with 1.7 t of KC_2H_3O_2, accumulated deep underground during ~1 yr, were reanalyzed to set limits on di-nucleons (nn and np) decays into invisible channels (disappearance, decay into neutrinos, etc.). The obtained lifetime bounds tau_np > 2.1 10^25 yr and tau_nn > 4.2 10^25 yr (at 90% C.L.) are better (or competitive) than those established in the recent experiments.Comment: 3 pages, accepted in JETP Letter

The quality assurance system of the trusted Microelectronic production

Trust (in reliable and safe operation) in a microelectronics product is mainly «laid down» at the stage of its development and is managed by guarantees of quality and reliability, the developer's qualifications and experience, a rational choice of key technical solutions that implement specified functional and operational characteristics, as well as parrying the main threats to its safety. Similarly, trust in products during their pilot and mass production is managed by the results of effective interaction and a rational combination of two systems: (1) managing the quality and protection of the manufacturer of products (i.e., using trusted processes) and (2) controlling production batches and samples of finished products (i.e., checking the reliability of a complex of technical means). This interaction implements a mutual «transfer of trust» to production processes and finished products – the possibility of spreading trust in production processes to trust in finished products and vice versa. At the stage of mass production, it is necessary first of all to ensure the stability of functional and operational characteristics, as well as acceptable technical and economic indicators of the product while maintaining the quality and protection levels inherent in its development. The article presents the results of an analysis of the critical stages of the microelectronics products production, typical threats arising at these stages, and methods of their parrying. There results allow us to build trust in such products (trust in their reliability and quality)

Big-Bang Nucleosynthesis and Hadronic Decay of Long-Lived Massive Particles

We study the big-bang nucleosynthesis (BBN) with the long-lived exotic particle, called X. If the lifetime of X is longer than \sim 0.1 sec, its decay may cause non-thermal nuclear reactions during or after the BBN, altering the predictions of the standard BBN scenario. We pay particular attention to its hadronic decay modes and calculate the primordial abundances of the light elements. Using the result, we derive constraints on the primordial abundance of X. Compared to the previous studies, we have improved the following points in our analysis: The JETSET 7.4 Monte Carlo event generator is used to calculate the spectrum of hadrons produced by the decay of X; The evolution of the hadronic shower is studied taking account of the details of the energy-loss processes of the nuclei in the thermal bath; We have used the most recent observational constraints on the primordial abundances of the light elements; In order to estimate the uncertainties, we have performed the Monte Carlo simulation which includes the experimental errors of the cross sections and transfered energies. We will see that the non-thermal productions of D, He3, He4 and Li6 provide stringent upper bounds on the primordial abundance of late-decaying particle, in particular when the hadronic branching ratio of X is sizable. We apply our results to the gravitino problem, and obtain upper bound on the reheating temperature after inflation.Comment: 94 pages, 49 figures, to appear in Phys. Rev. D. This is a full length paper of the preprint astro-ph/040249

Deuteron NN*(1440) components from a chiral quark model

We present a nonrelativistic coupled-channel calculation of the deuteron structure including Delta Delta and NN^*(1440) channels, besides the standard NN S and D-wave components. All the necessary building blocks to perform the calculation have been obtained from the same underlying quark model. The calculated NN^*(1440) probabilities find support in the explanation given to different deuteron reactions.Comment: 4 pages; revtex4, Accepted for publication in Phys. Rev. C (Brief Report

Single layer nickel disilicide on surface and as embedded layer

Single monolayers of various materials (e.g. graphene, silicene, bismuthene, plumbene, etc) have recently become fascinating and promising objects in modern condensed-matter physics and nanotechnology. However, growing a monolayer of non-layered material is still challenging. In the present report, it will be shown that single monolayer NiSi2 can be fabricated at Si(111) surface stabilized by either Tl, Pb or In monolayers. Nickel atoms were found to intercalate the stabilizing metal layers upon deposition and to reside in the interstitial sites inside the first silicon bilayer of bulk-like-terminated Si(111)1×1 surface. The interstitial positions almost coincide with the bulk NiSi2 atomic positions thus forming NiSi2 single layer. Atomic and electronic structure of formed systems is described in detail by means of a set of experimental techniques, including low-energy electron diffraction, scanning tunneling microscopy, angle-resolved photoemission spectroscopy and also first-principles density-functional-theory calculations. Quality of formed single monolayer NiSi2 was additionally confirmed by in situ four-probe transport measurements that show that single monolayer NiSi2 preserves a metallic-type conductivity down to 2.0 K. Moreover it was found that delta-type structure with atomic sheet of NiSi2 silicide embedded into a crystalline Si matrix can be fabricated using room-temperature overgrowth of a Si film onto the Tl stabilized NiSi2 surface layer. Confinement of the NiSi2 layer to a single atomic plane has been directly confirmed by high-resolution transmission electron microscopy

Cytokine profile in psoriatic arthritis: search for relationships with inflammation and blood rheological properties

Objective. To estimate the serum levels of interleukins (IL) 6 and 10, tumor necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) in patients with psoriatic arthritis (PSA) and their relationship with the clinical and laboratory parameters of inflammation and with erythrocyte aggregation (EA). Material and methods. The authors measured the serum levels of C-reactive protein (CRP) by immunonephelometry (BN, ProSPEC, Siemens) and those of TNF-α, IL-6 and IL-10, and VEGF by X-MAP technology using a BioPlex-200 system (Panel Human 27-Plex Bio-Rad, USA) in 80 patients with PSA [45 women and 35 men; mean age 41.7±10.5 years, mean duration of PSA and psoriasis was 5.0 (2.0; 12,5) and 15 (4; 26) years, respectively; DAS 3.9 (3.09; 5.16)]. The blood samples from 16 healthy donors matched to the examinees for gender and age served as a control. The parameters of EA [Т1(с); Кt (arb. units); β (с-1), I2,5 (%)] were estimated, by recording the rate of back light scattering. The median (Me) and interquartile range [Q25; Q75], and mean and standard deviations (M±σ) were calculated; the indicators were compared by the Mann-Whitney test and Student's t test. Correlation analysis was made using the Spearman rank correlation coefficient (R); p < 0.05 was considered statistically significant. Results. There were significantly higher serum levels of IL-6 and IL-10, TNF-α, and VEGF in patients with PSA than in the controls, and impaired blood rheological properties. There were significant correlations of the level of most cytokines (IL-6 and IL-10, VEGF) with both the values of the clinical and laboratory activity of PSA (self-rated pain, the number of swollen and tender joints, a physician's assessment of disease activity, DAS, erythrocyte sedimentation rate, and fibrinogen) and most parameters of EA (Т1, Kt и I2.5). No significant relationships were found between VEGF and CRP. Conclusion. The enhanced clinical and laboratory activity of PSA is attended by the systemic activation of immunological mediators of inflammation and neoangiogenesis and by impaired blood rheological properties, which supports the interaction of these factors in the immunopathogenesis of the diseases