Structure of sunspot light bridges in the chromosphere and transition region

Light bridges (LBs) are elongated structures with enhanced intensity embedded in sunspot umbra and pores. We studied the properties of a sample of 60 LBs observed with the Interface Region Imaging Spectrograph (IRIS). Using IRIS near- and far-ultraviolet spectra, we measured the line intensity, width, and Doppler shift; followed traces of LBs in the chromosphere and transition region (TR); and compared LB parameters with umbra and quiet Sun. There is a systematic emission enhancement in LBs compared to nearby umbra from the photosphere up to the TR. Light bridges are systematically displaced toward the solar limb at higher layers: the amount of the displacement at one solar radius compares well with the typical height of the chromosphere and TR. The intensity of the LB sample compared to the umbra sample peaks at the middle/upper chromosphere where they are almost permanently bright. Spectral lines emerging from the LBs are broader than the nearby umbra. The systematic redshift of the Si IV line in the LB sample is reduced compared to the quiet Sun sample. We found a significant correlation between the line width of ions arising at temperatures from 3x10^4 to 1.5x10^5 K as there is also a strong spatial correlation among the line and continuum intensities. In addition, the intensity-line width relation holds for all spectral lines in this study. The correlations indicate that the cool and hot plasma in LBs are coupled. Light bridges comprise multi-temperature and multi-disciplinary structures extending up to the TR. Diverse heating sources supply the energy and momentum to different layers, resulting in distinct dynamics in the photosphere, chromosphere, and TR.Comment: 12 pages, 9 figures, accepted in A&

Nutritional and Regulatory Roles for Branched-Chain Amino Acids in Milk Production by Lactating Sows

Both feeding and cell culture studies were conducted to test the hypothesis that branched-chain amino acids (BCAA) can enhance milk synthesis by porcine mammary epithelial cells (PMEC). In the first in vivo feeding trial, ten multiparous lactating sows were fed corn-soybean meal-based diets supplemented with 0%, 1.535%, or 3.07% BCAA for 29 d. The number of piglets was standardized to 9 per sow. On d 3,15 and 29 of lactation, body weights of sows and their piglets, as well as milk consumption of piglets were determined. Blood samples were obtained from sows and piglets at 2 and 1 h after feeding, respectively. The second feeding experiment was conducted with dietary supplements containing 0%, 1% or 2% monosodium glutamate (MSG). Data were analyzed by two-way ANOVA. In both feeding trials, plasma concentrations of aspartate, glutamine, citrulline, arginine, and BCAA were higher, compared to the control. Dietary supplementation with 1.535% and 3.07% BCAA increased: 1) concentrations of free and protein-bound glutamate plus glutamine in milk; 2) milk intake of piglets by 14% and 21%; and 3) daily weight gains of piglets by 19% and 28%. Dietary supplementation with 1% and 2% MSG increased: 1) concentrations of free and protein-bound glutamate plus glutamine in milk; 2) milk intake of piglets by 14% and 25%; and 3) daily weight gains of piglets by 23% and 44%. These results indicated that dietary supplementation with up to 3.07% BCAA or 2% MSG was safe and enhanced lactation in sows. To elucidate the mechanisms responsible for the effects of BCAA on milk production, PMEC were cultured in customized medium containing 0.1, 0.25, 0.5, 1 or 2 mM L- leucine, L-isoleucine, or L-valine, or a mixture of those three BCAA. Elevating extracellular concentrations of BCAA from 0.1 to 2 mM increased the phosphorylation of proteins in the mechanistic target of rapamycin pathway, the rate of protein synthesis and cell proliferation, while decreasing the abundance of proteasome and ubiquitinated protein, and the rate of protein degradation in PMEC. The findings not only advance understanding of nutritional regulation of lactation but also provide a new strategy to improve milk production by livestock, women, and other mammals

Viscous interfacial layer formation causes electroosmotic mobility reversal in monovalent electrolytes

We study the ion density, shear viscosity and electroosmotic mobility of an aqueous monovalent electrolyte at a charged solid surface using molecular dynamics simulations. Upon increasing the surface charge density, ions are displaced first from the diffuse layer to the outer Helmholtz layer, increasing its viscosity, and subsequently to the hydrodynamically stagnant inner Helmholtz layer. The ion redistribution causes both charge inversion and reversal of the electroosmotic mobility. Because of the surface-charge dependent interfacial hydrodynamic properties, however, the charge density of mobility reversal differs from the charge density of charge inversion, depending on the salt concentration and the chemical details of the ions and the surface. Mobility reversal cannot be described by an effective slip boundary condition alone – the spatial dependence of the viscosity is essential

Chromospheric impact of an exploding solar granule

Observations of multi-wavelength and therefore height-dependent information following events throughout the solar atmosphere and unambiguously assigning a relation between these rapidly evolving layers are rare and difficult to obtain. Yet, they are crucial for our understanding of the physical processes that couple the different regimes in the solar atmosphere. We characterize the exploding granule event with simultaneous observations of Hinode spectroplarimetric data in the solar photosphere and Hinode broadband CaIIH images combined with Interface Region Imaging Spectrograph (IRIS) slit spectra. We follow the evolution of an exploding granule and its connectivity throughout the atmosphere and analyze the dynamics of a magnetic element that has been affected by the abnormal granule. In addition to magnetic flux maps we use a local correlation tracking method to infer the horizontal velocity flows in the photosphere and apply a wavelet analysis on several IRIS chromospheric emission features such as MgIIk2v and MgIIk3 to detect oscillatory phenomena indicating wave propagation. During the vigorous expansion of the abnormal granule we detect radially outward horizontal flows, causing, together with the horizontal flows from the surrounding granules, the magnetic elements in the bordering intergranular lanes to be squeezed and elongated. In reaction to the squeezing, we detect a chromospheric intensity and velocity oscillation pulse which we identify as an upward traveling hot shock front propagating clearly through the IRIS spectral line diagnostics of MgIIh&k. Conclusion: Exploding granules can trigger upward-propagating shock fronts that dissipate in the chromosphere.Comment: 5 pages (3 figures)+1 page movie snapshots(2 figures), accepted in A&A letters, movies can be found at http://www.science-media.org/216 and http://www.science-media.org/21

Evaluation of Rotation Effects in Steel Structures with Irregular Plan Under Earthquake in Project Management

Abstract. Because of lacking specific relationships and criteria for steel structures with bending frames and braces along with the uneven bearing system in Iranian regulations, the need to study the behavior of such structures has been considered by researchers. In this paper, with three-dimensional modeling of steel structures with six types of plans, each of which indicates a degree of asymmetry of the load-bearing system, a total of 18 models of structures under two types of linear dynamic loading and overload were studied. It is indicated that with increasing unevenness of the load-bearing system, the rotation of the structures also increases. This increase is up to 18 times more for short-term structures and up to five times more than for parallel structures than parallel structures. The discrepancy causes unexpected results. Increasing the height of the structure reduces the rotation in the diaphragm. There is no difference between the rotation of the diaphragms in terms of elastic and inelastic, while the load in the other direction of these changes for the inelastic state is sometimes up to more than 50 times the elastic state

A distinct magnetic property of the inner penumbral boundary

A sunspot emanates from a growing pore or protospot. In order to trigger the formation of a penumbra, large inclinations at the outskirts of the protospot are necessary. The penumbra develops and establishes by colonising both umbral areas and granulation. Evidence for a unique stable boundary value for the vertical component of the magnetic field strength, $B^{\rm stable}_{\rm ver}$, was found along the umbra-penumbra boundary of developed sunspots. We use broadband G-band images and spectropolarimetric GFPI/VTT data to study the evolution of and the vertical component of the magnetic field on a forming umbra-penumbra boundary. For comparison with stable sunspots, we also analyse the two maps observed by Hinode/SP on the same spot after the penumbra formed. The vertical component of the magnetic field, $B_{\rm ver}$, at the umbra-penumbra boundary increases during penumbra formation owing to the incursion of the penumbra into umbral areas. After 2.5 hours, the penumbra reaches a stable state as shown by the GFPI data. At this stable stage, the simultaneous Hinode/SP observations show a $B_{\rm ver}$ value comparable to that of umbra-penumbra boundaries of fully fledged sunspots. We confirm that the umbra-penumbra boundary, traditionally defined by an intensity threshold, is also characterised by a distinct canonical magnetic property, namely by $B^{\rm stable}_{\rm ver}$. During the penumbra formation process, the inner penumbra extends into regions where the umbra previously prevailed. Hence, in areas where $B_{\rm ver} < B^{\rm stable}_{\rm ver}$, the magneto-convection mode operating in the umbra turns into a penumbral mode. Eventually, the inner penumbra boundary settles at $B^{\rm stable}_{\rm ver}$, which hints toward the role of $B_{\rm ver}^{\rm stable}$ as inhibitor of the penumbral mode of magneto-convection.Comment: Accepted as a Letter to A&A. Reproduced with permission from Astronomy & Astrophysics, \copyright ES

Multisensor Data Fusion Strategies for Advanced Driver Assistance Systems

Multisensor data fusion and integration is a rapidly evolving research area that requires interdisciplinary knowledge in control theory, signal processing, artificial intelligence, probability and statistics, etc. Multisensor data fusion refers to the synergistic combination of sensory data from multiple sensors and related information to provide more reliable and accurate information than could be achieved using a single, independent sensor (Luo et al., 2007). Actually Multisensor data fusion is a multilevel, multifaceted process dealing with automatic detection, association, correlation, estimation, and combination of data from single and multiple information sources. The results of data fusion process help users make decisions in complicated scenarios. Integration of multiple sensor data was originally needed for military applications in ocean surveillance, air-to air and surface-to-air defence, or battlefield intelligence. More recently, multisensor data fusion has also included the nonmilitary fields of remote environmental sensing, medical diagnosis, automated monitoring of equipment, robotics, and automotive systems (Macci et al., 2008). The potential advantages of multisensor fusion and integration are redundancy, complementarity, timeliness, and cost of the information. The integration or fusion of redundant information can reduce overall uncertainty and thus serve to increase the accuracy with which the features are perceived by the system. Multiple sensors providing redundant information can also serve to increase reliability in the case of sensor error or failure. Complementary information from multiple sensors allows features in the environment to be perceived that are impossible to perceive using just the information from each individual sensor operating separately. (Luo et al., 2007) Besides, driving as one of our daily activities is a complex task involving a great amount of interaction between driver and vehicle. Drivers regularly share their attention among operating the vehicle, monitoring traffic and nearby obstacles, and performing secondary tasks such as conversing, adjusting comfort settings (e.g. temperature, radio.) The complexity of the task and uncertainty of the driving environment make driving a very dangerous task, as according to a study in the European member states, there are more than 1,200,000 traffic accidents a year with over 40,000 fatalities. This fact points up the growing demand for automotive safety systems, which aim for a significant contribution to the overall road safety (Tatschke et al., 2006). Therefore, recently, there are an increased number of research activities focusing on the Driver Assistance System (DAS) development in order O pe n A cc es s D at ab as e w w w .in te ch w eb .o r