Hyperon Polarization in the Constituent Quark Model

We consider mechanism for hyperon polarization in inclusive production. The main role belongs to the orbital angular momentum and polarization of the strange quark-antiquark pairs in the internal structure of the constituent quarks. We consider a nucleon as a core consisting of the constituent quarks embedded into quark condensate. The nonperturbative hadron structure is based on the results of chiral quark models.Comment: 14 pages, LaTeX, 2 Figures, References adde

Transverse Λ0\Lambda^0 polarization in inclusive quasi-real photoproduction at the current fragmentation

It is shown that the recent HERMES data on the transverse $\Lambda^0$ polarization in the inclusive quasi-real photoproduction at $x_F>0$ can be accommodated by the strange quark scattering model. Relations with the quark recombination approach are discussed.Comment: 5 pages, 3 figures, accepted by Eur. Phys. J.

Lambda polarization and single-spin left-right asymmetry in diffractive hadron-hadron collisions

We discuss Lambda polarization and single-spin left-right asymmetry in diffractive hadron-hadron scattering at high energies. We show that the physical picture proposed in a recent Letter is consistent with the experimental observation that $\Lambda$ polarization in the diffractive process, $pp\to \Lambda K^+p$, is much higher than that in the inclusive reaction, $pp\to \Lambda X$. We make predictions for the left-right asymmetry, A_N, and for the spin transfer, $D_{NN}^\Lambda$, in the single-spin process $p(\uparrow)p\to \Lambda K^+p$ and suggest further experimental tests of the proposed picture.Comment: 14 pages, 3 ps-figures. Phys. Rev. D (in press

Information transmission in oscillatory neural activity

Periodic neural activity not locked to the stimulus or to motor responses is usually ignored. Here, we present new tools for modeling and quantifying the information transmission based on periodic neural activity that occurs with quasi-random phase relative to the stimulus. We propose a model to reproduce characteristic features of oscillatory spike trains, such as histograms of inter-spike intervals and phase locking of spikes to an oscillatory influence. The proposed model is based on an inhomogeneous Gamma process governed by a density function that is a product of the usual stimulus-dependent rate and a quasi-periodic function. Further, we present an analysis method generalizing the direct method (Rieke et al, 1999; Brenner et al, 2000) to assess the information content in such data. We demonstrate these tools on recordings from relay cells in the lateral geniculate nucleus of the cat.Comment: 18 pages, 8 figures, to appear in Biological Cybernetic

Clinical, echocardiographic, and pacing parameters affecting atrial fibrillation burden in patients with tachycardia-bradycardia syndrome

Background: The influence of various factors on atrial fibrillation (AF) development in the population of tachycardia-bradycardia syndrome (TBS) patients remains unclear. There are no data on the impact of different right ventricular pacing percentage (RVp%) profiles. Aim: The purpose of the study was to evaluate the relationship between the AF burden (AFB) and various clinical, echocardiographic, and pacing parameters in TBS patients. Methods: We performed a prospective, one-year registry of TBS patients with documented AF referred for dual-chamber pacemaker (DDD) implantation. Results: The data of 65 patients were analysed. The median 12-month RVp% and AFB was 9.4% and 1.0%, respectively. During the follow-up 14% of patients had no AF (p = 0.003), and the withdrawal of AF symptoms was observed in 49% of patients (p < 0.0001). The AFB was related to the left atrium diameter (r = 0.31, p = 0.02), especially in the subjects with left ventricular ejection fraction < 60% (r = 0.44, p = 0.04). Based on the relative change of RVp%, three groups of various RVp% profile were established: stable, decreasing, and increasing RVp%. In the stable RVp% group (n = 21) there was a quadratic correlation between the 12-month RVp% and AFB (r = 0.71, p = 0.0003). In the stable RVp% > 20% subgroup there was a significant increase of AFB in comparison to the RVp% ≤ 20% subgroup (ΔAFB 1.8% vs. 0.0%, p = 0.03, respectively). In the increasing RVp% group (n = 28) the AFB increased whereas in the decreasing RVp% (n = 16) it remained stable (ΔAFB 0.67% vs. 0.0%, p = 0.034, respectively). Conclusions: DDD implantation in TBS patients is related to a significant reduction in AF symptoms, and left atrial diameter correlates with cumulative AFB in the mid-term observation. Stable RVp% > 20% is associated with AF progression whereas lower stable RVp% may stabilise AF development. Increasing RVp% may be associated with the AFB increase in comparison to the decreasing RVp% subgroup in which AFB remains stable.Background: The influence of various factors on atrial fibrillation (AF) development in the population of tachycardia-bradycardia syndrome (TBS) patients remains unclear. There are no data on the impact of different right ventricular pacing percentage (RVp%) profiles. Aim: The purpose of the study was to evaluate the relationship between the AF burden (AFB) and various clinical, echocardiographic, and pacing parameters in TBS patients. Methods: We performed a prospective, one-year registry of TBS patients with documented AF referred for dual-chamber pacemaker (DDD) implantation. Results: The data of 65 patients were analysed. The median 12-month RVp% and AFB was 9.4% and 1.0%, respectively. During the follow-up 14% of patients had no AF (p = 0.003), and the withdrawal of AF symptoms was observed in 49% of patients (p < 0.0001). The AFB was related to the left atrium diameter (r = 0.31, p = 0.02), especially in the subjects with left ventricular ejection fraction < 60% (r = 0.44, p = 0.04). Based on the relative change of RVp%, three groups of various RVp% profile were established: stable, decreasing, and increasing RVp%. In the stable RVp% group (n = 21) there was a quadratic correlation between the 12-month RVp% and AFB (r = 0.71, p = 0.0003). In the stable RVp% > 20% subgroup there was a significant increase of AFB in comparison to the RVp% ≤ 20% subgroup (ΔAFB 1.8% vs. 0.0%, p = 0.03, respectively). In the increasing RVp% group (n = 28) the AFB increased whereas in the decreasing RVp% (n = 16) it remained stable (ΔAFB 0.67% vs. 0.0%, p = 0.034, respectively). Conclusions: DDD implantation in TBS patients is related to a significant reduction in AF symptoms, and left atrial diameter correlates with cumulative AFB in the mid-term observation. Stable RVp% > 20% is associated with AF progression whereas lower stable RVp% may stabilise AF development. Increasing RVp% may be associated with the AFB increase in comparison to the decreasing RVp% subgroup in which AFB remains stable

Transverse Λ0\Lambda^0 polarization in inclusive quasi-real photoproduction: quark scattering model

The transverse polarization of $\Lambda^0$ hyperons produced in the inclusive $ep$ reaction at the 27.6 GeV beam energy is assumed to appear mostly via scattering of the strange quark in a color field. Results of application of such an idea to the preliminary data of HERMES are presented. Contributions of $\Sigma^0$, $\Xi$, and $\Sigma^*$ resonances to the polarization are taken into account.Comment: 5 pages, 5 figures, corrected according to version accepted by Physics of Atomic Nucle