Analysis of the Solar Flare Index for Solar Cycles 18-24: Extremely Deep Gnevyshev Gap in the Chromosphere

We study the solar flare index (SFI) for the solar cycles 18\,--\,24. We find that SFI has deeper Gnevyshev gap (GG) in its first principal component than other atmospheric parameters. The GG is extremely clear especially in the even cycles. The GG of the SFI appears about a half year later as a drop in the interplanetary magnetic field near the Earth and in the geomagnetic Ap-index. The instantaneous response of the magnetic field to solar flares, however, shows about two to three days after the eruption as a high, sharp peak in the cross-correlation of the SFI and Ap-index and as a lower peak in SFI vs. IMF B cross-correlation. We confirm these rapid responses using superposed-epoch analysis. The most active flare cycles during 1944-2020 are the Cycles 19 and 21. The Cycle 18 has very strong SFI days as much as Cycle 22, but it has least nonzero SFI days in the whole interval. Interestingly Cycle 20 can be compared to the Cycles 23 and 24 in its low flare activity, although it locates between the most active SFI cycles.Comment: accepted to Solar Physics, 25 pages, 16 figure

Evaluation of the orientation distribution of fibers from reflection images of fibrous samples

Peer reviewe

Regulation of excitation-contraction coupling in mouse cardiac myocytes: integrative analysis with mathematical modelling

<p>Abstract</p> <p>Background</p> <p>The cardiomyocyte is a prime example of inherently complex biological system with inter- and cross-connected feedback loops in signalling, forming the basic properties of intracellular homeostasis. Functional properties of cells and tissues have been studied e.g. with powerful tools of genetic engineering, combined with extensive experimentation. While this approach provides accurate information about the physiology at the endpoint, complementary methods, such as mathematical modelling, can provide more detailed information about the processes that have lead to the endpoint phenotype.</p> <p>Results</p> <p>In order to gain novel mechanistic information of the excitation-contraction coupling in normal myocytes and to analyze sophisticated genetically engineered heart models, we have built a mathematical model of a mouse ventricular myocyte. In addition to the fundamental components of membrane excitation, calcium signalling and contraction, our integrated model includes the calcium-calmodulin-dependent enzyme cascade and the regulation it imposes on the proteins involved in excitation-contraction coupling. With the model, we investigate the effects of three genetic modifications that interfere with calcium signalling: 1) ablation of phospholamban, 2) disruption of the regulation of L-type calcium channels by calcium-calmodulin-dependent kinase II (CaMK) and 3) overexpression of CaMK. We show that the key features of the experimental phenotypes involve physiological compensatory and autoregulatory mechanisms that bring the system to a state closer to the original wild-type phenotype in all transgenic models. A drastic phenotype was found when the genetic modification disrupts the regulatory signalling system itself, i.e. the CaMK overexpression model.</p> <p>Conclusion</p> <p>The novel features of the presented cardiomyocyte model enable accurate description of excitation-contraction coupling. The model is thus an applicable tool for further studies of both normal and defective cellular physiology. We propose that integrative modelling as in the present work is a valuable complement to experiments in understanding the causality within complex biological systems such as cardiac myocytes.</p

Microsaccadic sampling of moving image information provides Drosophila hyperacute vision.

Small fly eyes should not see fine image details. Because flies exhibit saccadic visual behaviors and their compound eyes have relatively few ommatidia (sampling points), their photoreceptors would be expected to generate blurry and coarse retinal images of the world. Here we demonstrate that Drosophila see the world far better than predicted from the classic theories. By using electrophysiological, optical and behavioral assays, we found that R1-R6 photoreceptors' encoding capacity in time is maximized to fast high-contrast bursts, which resemble their light input during saccadic behaviors. Whilst over space, R1-R6s resolve moving objects at saccadic speeds beyond the predicted motion-blur-limit. Our results show how refractory phototransduction and rapid photomechanical photoreceptor contractions jointly sharpen retinal images of moving objects in space-time, enabling hyperacute vision, and explain how such microsaccadic information sampling exceeds the compound eyes' optical limits. These discoveries elucidate how acuity depends upon photoreceptor function and eye movements

Evaluation of structural irregularities based on architectural design considerations in Turkey

Purpose: The purpose of this research is to show significant points which can be used in the architectural design process by investigating the basic principles of earthquake resistant design (ERD) in a deductive format and to contribute to the architectural perception in ERD. Design/methodology/approach: First, the structural irregularity types are examined depending on the rules defined in the Turkish Earthquake Code, 2007 (TEC). Then, architectural design failures related to earthquake resistance of buildings under earthquake loading are visualized and solution suggestions in literature are described in detail by supported drawings. Findings: The problems causing structural irregularities are investigated deeply with given solutions in literature. It is obtained that the significant factors affecting the earthquake performance of structures are: architectural form, structural configuration, slenderness ratio, the location and rate of floor openings, projection rates and symmetry, rigidity and strength differences between floors, short columns, pounding effect. Social implications - The practical design decision rules can contribute to the phenomena of earthquake resistant architectural design and can encourage adoption of these rules in building industry. Originality/value: This study aims to gain an understanding of the problems in projects in terms of structural irregularities, and then manage to solve the problems using problem-oriented approaches. The suggested solutions can be adopted and applied to future projects for designing earthquake resistant buildings