Doppler and proper motions accompanying formation of an additional magnetic flux in the mature solar active region (NOAA 7216)

We document the evolution of an additional magnetic flux in the photosphere of a fully developed sunspot group, we measure longitudinal magnetic field, line-of-sight motions, and proper motions of sunspots in the group during this process. We demonstrate the close correlation of magnetic field, Doppler and proper motion singularities with the area in which additional magnetic flux appears and the new penumbrae and umbrae develop. We discuss the probable reasons for this fact and for the region's weak flare activity. There exist in the group about eight sunspots with the Evershed effect, differing in form, in dependence on the history of development of the spot in which it is observed

The 1991 southern hemisphere complex of activity

We have investigated the development of a complex of activity which took place in the southern hemisphere of the Sun between July 1991 and April 1992. The whole process culminated with the successive formation of two large active regions with sunspot groups NOAA 6850 (September/October) and NOAA 6891 (October/November 1991), both having complicated magnetic fields, but the former without heavy flare activity. We observed the appearance of the individual active regions as the consequence of the development stage of large-scale magnetic fields in the given area of the solar surface, in connection with their longitudinal and latitudinal distribution. We have studied the dynamics of this development on magnetic synoptic charts, as well as on spectroheliograms taken in the K-line of ionized calcium. Our new observations confirm the regularities found earlier and connection of global and local developments with convection. We think that they could become a tool for solar activity prediction and that they could be used for comparative studies of stellar complexes of activity

Dynamics of Anguillicola crassus (Nematoda: Dracunculoidea) infection in eels of lake Balaton, Hungary

Following the introduction of Anguillicola crassus into Lake Balaton, by 1991 the entire eel population became infected. At the same time, marked differences existed in the prevalence and intensity of infection between different areas of the lake. The highest prevalence values occurred in the eastern basin less densely populated with eels, while in the western basin a large proportion of the fish were free of infection. Helminth-free status accompanied by thickening of the swimbladder wall developed after intensive infections. In 1991, eel mortality could be observed only in the western basin. In 1992, the number of eels with swimbladders having a thickened wall but not containing helminths increased also in the central and eastern areas of the lake. Parallel to this, a mortality less expressed than the one in 1991 occurred in the central part of the lake. By 1993, a host-parasite equilibrium had become established in Lake Balaton

The power of wavelets in analysis of transit and phase curves in presence of stellar variability and instrumental noise III. Accuracy of transit parameters

Correlated noise in exoplanet light curves, such as noises from stellar activity, convection noise, and instrumental noises distorts the exoplanet transit light curves, and leads to biases in the best-fit transit parameters. An optimal fitting algorithm is stable against the presence of correlated noises and lead to statistically consistent results, i.e. the actual biases are usually within the error interval. This is not automatically satisfied by most of the algorithms in everyday use, and the testing of the algorithms is necessary. In this paper, we describe a bootstrapping-like test to handle with the general case, and apply this to the wavelet-based TLCM (Transit and Light Curve Modeller) algorithm, testing it for the stability against the correlated noise. We contrast the results to the FITSH algorithm that is based on a white noise assumption. We simulated transit light curves with previously known parameters in the presence of a correlated noise model generated by an ARIMA (Autoregressive Integretad Moving Average) process. Then we solved the simulated observations, and examined the resulting parameters and error intervals. We have found that the assumption of FITSH that only white noise is present led to inconsistencies in the results: the distribution of best-fit parameters is by a factor of 3--6 broader then the determined error intervals. On the other hand, the wavelet-based TLCM algorithm handles the correlated noise properly, leading to properly determined parameter and error intervals which are perfectly consistent with the actual biases.Comment: Submitted to A&A, favorable referee report received, 11 pages, 8 figure

Characteristics of Glial Reaction in the Perinatal Rat Cortex: Effect of Lesion Size in the ‘Critical Period’

In this study we investigate the capability of lesions, performed between embryonic day E18 and postnatal day P6, to provoke glial reaction. Two different lesion types were applied: ‘severe’ lesion (tissue defect) and ’light’ lesion (stab wound). The glial reaction was detected with immunostain[ng against glial fibrillary acidic protein. When performed as early as P0, severe lesions could result in reactive gliosis, which persisted even after a month. The glial reaction was detected at P6/P7 and became strong by P8, regardless of the age when the animals were lesioned between P0 and P5. Namely, a strict limit could be estimated for the age when reactive glia were already found rather than for the age when glial reaction-provoking lesions could occur. After prenatal lesions, no glial reaction developed, but the usual glia limitans covered the deformed brain, surface. Light lesions provoked glial reactions when performed at P6. In conclusion, three scenarios were found, depending on the age of the animal at injury: (i) healing without glial reaction, regardless of the remaining deformation; (ii) depending on the size of the lesion, either healing without residuum or with remaining tissue defect plus reactive gliosis; and (iii) healing always with reactive gliosis. The age limits between them were at P0 and P5. The glial reactivity seemingly appears after the end of the neuronal migration and just precedes the massive transformation of the radial glia into astrocytes. Estimating the position of the appearance of glial reactivity among the events of cortical maturation can help to adapt the experimental results to humans

Quantum rings with time dependent spin-orbit coupling: Rabi oscillations, spintronic Schrodinger-cat states, and conductance properties

The strength of the (Rashba-type) spin-orbit coupling in mesoscopic semiconductor rings can be tuned with external gate voltages. Here we consider the case of a periodically changing spin-orbit interaction strength as induced by sinusoidal voltages. In a closed one dimensional quantum ring with weak spin-orbit coupling, Rabi oscillations are shown to appear. We find that the time evolution of initially localized wave packets exhibits a series of collapse and revival phenomena. Partial revivals -- that are typical in nonlinear systems -- are shown to correspond to superpositions of states localized at different spatial positions along the ring. These "spintronic Schrodinger-cat sates" appear periodically, and similarly to their counterparts in other physical systems, they are found to be sensitive to environment induced disturbances. The time dependent spin transport problem, when leads are attached to the ring, is also solved. We show that the "sideband currents" induced by the oscillating spin-orbit interaction strength can become the dominant output channel, even in the presence of moderate thermal fluctuations and random scattering events.Comment: 11 pages, 9 figures, submitted to PR

Magnetoconductance properties of rectangular arrays of spintronic quantum rings

Electron transport through multi-terminal rectangular arrays of quantum rings is studied in the presence of Rashba-type spin-orbit interaction (SOI) and of a perpendicular magnetic field. Using the analytic expressions for the transmission and reflection coefficients for single rings we obtain the conductance through such arrays as a function of the SOI strength, the magnetic flux, and of the wave vector $k$ of the incident electron. Due to destructive or constructive spin interferences caused by the SOI, the array can be totally opaque for certain ranges of $k$, while there are parameter values where it is completely transparent. Spin resolved transmission probabilities show nontrivial spin transformations at the outputs of the arrays. When point-like random scattering centers are placed between the rings, the Aharonov-Bohm peaks split, and an oscillatory behavior of the conductance emerges as a function of the SOI strength.Comment: 10 pages, 10 figures, submitted to PR