Permissive Modulation of Sphingosine-1-Phosphate-Enhanced Intracellular Calcium on BKCa Channel of Chromaffin Cells

Sphingosine-1-phosphate (S1P), is a signaling sphingolipid which acts as a bioactive lipid mediator. We assessed whether S1P had multiplex effects in regulating the large-conductance Ca²⁺-activated K⁺ channel (BK_Ca) in catecholamine-secreting chromaffin cells. Using multiple patch-clamp modes, Ca²⁺ imaging, and computational modeling, we evaluated the effects of S1P on the Ca²⁺-activated K⁺ currents (I_K(Ca)) in bovine adrenal chromaffin cells and in a pheochromocytoma cell line (PC12). In outside-out patches, the open probability of BK_Ca channel was reduced with a mean-closed time increment, but without a conductance change in response to a low-concentration S1P (1 µM). The intracellular Ca²⁺ concentration (Ca_i) was elevated in response to a high-dose (10 µM) but not low-dose of S1P. The single-channel activity of BK_Ca was also enhanced by S1P (10 µM) in the cell-attached recording of chromaffin cells. In the whole-cell voltage-clamp, a low-dose S1P (1 µM) suppressed I_K(Ca), whereas a high-dose S1P (10 µM) produced a biphasic response in the amplitude of I_K(Ca), i.e., an initial decrease followed by a sustained increase. The S1P-induced I_K(Ca) enhancement was abolished by BAPTA. Current-clamp studies showed that S1P (1 µM) increased the action potential (AP) firing. Simulation data revealed that the decreased BK_Ca conductance leads to increased AP firings in a modeling chromaffin cell. Over a similar dosage range, S1P (1 µM) inhibited I_K(Ca) and the permissive role of S1P on the BK_Ca activity was also effectively observed in the PC12 cell system. The S1P-mediated I_K(Ca) stimulation may result from the elevated Ca_i, whereas the inhibition of BK_Ca activity by S1P appears to be direct. By the differentiated tailoring BK_Ca channel function, S1P can modulate stimulus-secretion coupling in chromaffin cells.     

Homonuclear Decoupling of 1H Dipolar Interactions in Solids by means of Heteronuclear Recoupling

Line narrowing has been traditionally achieved in solid-state ¹H NMR spectroscopy by applying pulse sequences that combine multiple-pulse operations with magic-angle spinning (MAS), to effectively average out the dipole dipole homonuclear Hamiltonian. The present study explores a new alternative that departs from the usual concept of directly acting on the strongly coupled spins with radiofrequency pulses; instead, we seek to achieve a net homonuclear dipolar decoupling in solids by exploring the reintroduction of MAS-averaged heteronuclear dipolar couplings between the ¹H nuclei and directly bonded ¹³C or ¹⁵N nuclei. This recoupling anti-recoupling (RaR) scheme thus relies on the recoupling of the dipolar interaction with heteronuclear spins, which, under fast MAS, will exceed the strength and will not commute with the homonuclear ¹H ¹H coupling one is intending to average out. Subsequent removal (“antiRecoupling”) of these heteronuclear interactions can lead to narrowed ¹H resonances, without ever pulsing on the aforementioned channel. The line-narrowing properties of RaR are illustrated with numerical simulations and with experiments on model organic solids.     

Initial value problem for fuzzy differential equations under dissipative conditions

A new concept of inner product on the fuzzy space (Eⁿ,D) is introduced, studied and used to prove several theorems stating the existence, uniqueness and boundedness of solutions of fuzzy differential equations. A stability result is also proved in the same context.     

Modeling beach realignment using a neuro-fuzzy network optimized by a novel backtracking search algorithm

Neural Computing and Applications - Beach realignment is caused by sediment movement across and along the beach due to the ever-changing incident waves. Its driving mechanisms are highly nonlinear...     

VisiMat-Software for the Visualization of Multicomponent Diffusion in Two and Three Dimensions

VisiMat is a MATLAB code with a graphical user interface (GUI) that is intended to be used for instructional purposes. It is designed to facilitate understanding of the complex multicomponent diffusion phenomena that may occur in couples of three or more components with a special emphasis on the compositions and locations where maxima, minima, or zero-flux behavior may occur. VisiMat is an implementation of the square-root diffusivity method for predicting and visualizing the diffusion behavior of ternary and quaternary, single-phase, multicomponent diffusion couples with constant diffusivity. The program determines concentration profiles, fluxes including zero-flux conditions, and two- or three-dimensional representations of composition space and diffusion path. Although the code will accomodate any number of components, the three-dimensional visualizations are not possible for more than four components.     

The use of sustainable combined cycle technologies in Cyprus: a case study for the use of LOTHECO cycle

In this work, a cost–benefit analysis concerning the use of the low temperature heat combined cycle (LOTHECO cycle) in Cyprus is carried out. Also, the expected main emissions from the LOTHECO cycle are compared with existing commercial technologies. In particular, the future generation system of Cyprus power industry is simulated by the independent power producers optimization algorithm and by the long-term expansion software Wien Automatic System Planning. Various conventional generation options are examined and compared with LOTHECO cycle parametric studies. The economic analysis, based on the assumptions used and the candidate technologies examined, indicated that in the case of conventional technologies the least cost solution is the natural gas combined cycle. Additional computer runs with the various LOTHECO cycle parametric studies indicated that for efficiencies greater than 60% and capital cost between 700 and 900 €/kW, LOTHECO cycle is the least cost generation technology. Furthermore, the current state and future improvements of the environmental indicators of the power industry in Cyprus are presented. It is estimated that by the use of LOTHECO cycle instead of the business as usual scenario, the principal environmental indicators would be reduced by the year 2010 by approximately −23% instead of −8%. Further, the carbon dioxide environmental indicator will be reduced by +24% instead of +68%.     

The Cicero Clay Pits,Onondaga County,New York

For at least fifteen years, concretions in the old clay pits near the village of Cicero in central New York State produced micro-sized specimens of eight common minerals in exquisite crystals. The many habits of calcite and goethite are particularly noteworthy. Material from this locality is familiar to micromounters, and large quantities of specimens were produced. Beyond mention in a few mineral club bulletins, however, nothing about this locality has appeared in the literature. Beginning in 1983, the locality was obliterated by a subdivision of houses. Here we document this interesting locality before the information is lost forever.     

Femtosecond modification of electron localization and transfer of angular momentum in nickel

The rapidly increasing information density required of modern magnetic data storage devices raises the question of the fundamental limits in bit size and writing speed. At present, the magnetization reversal of a bit can occur as quickly as 200 ps (ref. 1). A fundamental limit has been explored by using intense magnetic-field pulses of 2 ps duration leading to a non-deterministic magnetization reversal. For this process, dissipation of spin angular momentum to other degrees of freedom on an ultrafast timescale is crucial. An even faster regime down to 100 fs or below might be reached by non-thermal control of magnetization with femtosecond laser radiation. Here, we show that an efficient novel channel for angular momentum dissipation to the lattice can be opened by femtosecond laser excitation of a ferromagnet. For the first time, the quenching of spin angular momentum and its transfer to the lattice with a time constant of 120+/-70 fs is determined unambiguously with X-ray magnetic circular dichroism. We report the first femtosecond time-resolved X-ray absorption spectroscopy data over an entire absorption edge, which are consistent with an unexpected increase in valence-electron localization during the first 120+/-50 fs, possibly providing the driving force behind femtosecond spin-lattice relaxation.