Biblioteca Digital

The nature of the vasodilator endothelium-derived hyperpolarizing factor (EDHF) is controversial, putatively involving diffusible factors and/or electrotonic spread of hyperpolarization generated in the endothelium via myoendothelial gap junctions (MEGJs). In this study, we investigated the relationship between the existence of MEGJs, endothelial cell (EC) hyperpolarization, and EDHF-attributed smooth muscle cell (SMC) hyperpolarization in two different arteries: the rat mesenteric artery, where EDHF-mediated vasodilation is prominent, and the femoral artery, where there is no EDHF-dependent relaxation. In the rat mesenteric artery, stimulation of the endothelium with acetylcholine (ACh) evoked hyperpolarization of both ECs and SMCs, and characteristic pentalaminar MEGJs were found connecting the two cell layers. In contrast, in the femoral artery, ACh evoked hyperpolarization in only ECs but not in SMCs, and no MEGJs were present. Selective hyperpolarization of ECs or SMCs evoked hyperpolarization in the other cell type in the mesenteric artery but not in the femoral artery. Disruption of gap junctional coupling using the peptide Gap 27 markedly reduced the ACh-induced hyperpolarization in SMCs, but not in ECs, of the mesenteric artery. These results show that transfer of EC hyperpolarization or of a small molecule to SMCs through MEGJs is essential and sufficient to explain EDHF.

We report the fabrication of single crystal kinked ZnO [001] and [100] nanowires (NWs). From the detailed morphology and microstructure analyzed by transmission electron microscopy, we discuss the growth characteristics, including nucleation and kinking,

We have grown transition metal (Fe, Mn) doped GaN thin films on c-oriented sapphire by metal-organic chemical vapor deposition. By varying the flow of the metal precursor, a series of samples with different ion concentrations are synthesized. Microstructural properties are characterized by using a high-resolution transmission electron microscope. For Fe over-doped GaN samples, hexagonal Fe 3N clusters are observed with Fe 3N(0002) parallel to GaN (0002) while for Mn over-doped GaN, hexagonal Mn 6N 2.58 phases are observed with Mn 6N 2.58(0002) parallel to GaN(0002). In addition, with higher concentration ions doping into the lattice matrix, the partial lattice orientation is distorted, leading to the tilt of GaN(0002) planes. The magnetization of the Fe over-doped GaN sample is increased, which is ascribed to the participation of ferromagnetic iron and Fe 3N. The Mn over-doped sample displays very weak ferromagnetic behavior, which probably originates from the Mn 6N 2.58.

The paper presents a new approach for designing electromagnetic metamaterials which can be tuned by light. The results of experimental study of magnetic resonance behaviour of a tunable split-ring resonators loaded by a varactor diode and biased by a photodiode operated in photovoltaic mode are presented. The design and results of experimental investigation of light-controllable magnetic reflector array based on tunable split-ring resonators are also discussed.

We investigate nonlinear behavior of metamaterial element, where responses of a different nature are intrinsically coupled through its structure. We provide an experimental demonstration of the electromagnetically induced compression of the metamaterials

The shell model has been particularly successful in describing the structure of states near the doubly magic 208Pb core. In particular semi-empirical calculations are able to reproduce the yrast states in the three valence proton nucleus, 211At to a high

Absolute grand total, positronium formation, and grand total minus positronium formation cross sections for positron scattering from krypton and xenon have been measured with an energy resolution of ∼60 meV over the energy range 0.5-60 eV. Experimental

Objectives: Hypertension is accompanied by endothelial dysfunction. The present study has investigated endothelial cell morphology and connexin expression in the caudal artery of the rat during the development of hypertension. Methods: A significant increase in systolic blood pressure was detected from 9 weeks of age in spontaneously hypertensive male rats (SHR) compared to normotensive Wistar-Kyoto (WKY) rats, reaching a maximum by 11-12 weeks of age. Immunohistochemistry was used to quantify cell size and expression of connexins (Cxs) 37, 40 and 43 in the endothelium of prehypertensive (3-week-old) and hypertensive (12-week-old) rats. Results: At 12 weeks, the size of endothelial cells and the expression of all three Cxs per endothelial cell were significantly less in SHR than WKY rats. At 3 weeks, there was no significant difference in cell size nor in the expression of Cxs 37 or 43; however, expression of Cx40 was significantly lower in SHR than in WKY rats. Between 3 and 12 weeks in WKY rats, there was no change in endothelial cell size, nor in the expression of Cxs 37, 40 and 43. In SHR, both cell size and Cx expression per endothelial cell were significantly decreased during the same developmental period, with a significant decrease in the density of Cx40 plaques. Conclusion: The development of hypertension in the SHR is accompanied by significant decreases in endothelial cell size and expression of Cx40...

We present one of the most ultraviolet (UV) luminous Lyman break galaxies (LBGs; J1432+3358) at z = 2.78, discovered in the NOAO Deep Wide-Field Survey Boötes field. The R-band magnitude of J1432+3358 is 22.29AB, more than two magnitudes brighter than ty

Magnetic field-free measurements of the total cross sections for positron-neon and positron-argon scattering have been performed using an electrostatic high-brightness slow positron beam apparatus.

Objective - To determine the connexins (Cxs) involved in intercellular coupling within vascular muscle, the present study has quantified mRNA and protein expression for Cx37, Cx40, Cx43, and Cx45 in the caudal artery (CA) and thoracic aorta (ThA) of the rat. Methods and Results - Real-time polymerase chain reaction and immunohistochemistry identified Cx37 as the most abundantly expressed Cx in the CA, with fine punctate staining observed in the media. Conversely, mRNA for Cx43 was 40-fold greater in the ThA than in the CA, with punctate staining in the endothelium and media of the ThA but confined to the endothelium in the CA. Western blotting confirmed the differences in the relative amounts of Cx43 between the 2 vessels. For both arteries, Cx45 was expressed to a lesser degree in the media but not in the endothelium, whereas Cx40 was found only in the endothelium. Cx37, Cx40, and Cx43 were expressed in the endothelium of both vessels, although the density of Cx40 plaques was significantly greater in the CA. Conclusions - The demonstration of Cx37 as the dominant Cx in the media of the CA highlights the potential heterogeneity in Cx involvement in vascular smooth muscle.

Differential cross sections for electron impact excitation of the 5p state of silver have been measured in conjunction with relativistic distorted-wave calculations.

High-spin states have been populated in 176Ir using the 149Sm(31P,4n) reaction. Gamma-gamma coincidence techniques have allowed numerous bands up to a maximum spin of 32 to be identified. Configurations have been assigned based on spectroscopic properties such as B(M1)/B(E2) values and aligned angular momenta. Signature inversions are observed in bands based on the πh9/2⊗ vi13/2 and πi13/2⊗ vi13/2 configurations. These inversions are compared with particle-rotor model calculations and are qualitatively reproduced when a residual proton-neutron interaction is included. The shape evolution of the bands has been studied using diabatic potential energy surface calculations. A strong configuration dependence is predicted.

Spontaneous, rhythmical contractions, or vasomotion, can be recorded from cerebral vessels under both normal physiological and pathophysiological conditions. Using electrophysiology to study changes in membrane potential, the ratiometric calcium indicator Fura-2 AM to study changes in [Ca2+]i in both the arterial wall and in individual smooth muscle cells (SMCs), and video microscopy to study changes in vessel diameter, we have investigated the cellular mechanisms underlying vasomotion in the juvenile rat basilar artery. During vasomotion, rhythmical oscillations in both membrane potential and [Ca2+]i were found to precede rhythmical contractions. Nifedipine depolarized SMCs and abolished rhythmical contractions and depolarizations. [Ca2+]i oscillations in the arterial wall became reduced and irregular, while [Ca2+]i oscillations in adjacent SMCs were no longer synchronized. BAPTA-AM, thapsigargin and U73122 hyperpolarized SMCs, relaxed the vessel, decreased basal calcium levels and abolished vasomotion. Chloride substitution abolished rhythmical activity, depolarized SMCs, increased basal calcium levels and constricted the vessel, while niflumic acid and DIDS abolished vasomotion. Ryanodine, charybdotoxin and TRAM-34, but not iberiotoxin...

High-density, vertically aligned CrO2 nanowire arrays were obtained via atmospheric-pressure CVD assisted by AAO templates. The CrO 2 nanowire arrays show remarkably enhanced coercivity compared with CrO2 films or bulk. It was found that the length of the nanowires is greatly influenced by the pore diameter of the AAO template used. The growth mechanism and the pore size dependence of the CrO2 nanowire arrays are discussed. The present method provides a useful approach for the synthesis of CrO2 nanowire arrays. Such highly ordered nanowire arrays within an AAO template may have important applications in ultrahigh-density perpendicular magnetic recording devices and the mass production of spintronic nanodevices.

The topic of smart grids has received a lot of attention but from a scientific point of view it is a highly imprecise concept. This paper attempts to describe what could ultimately work as a control process to fulfill the aims usually stated for such grids without throwing away some important principles established by the pioneers in power system control. In modern terms, we need distributed (or multi-agent) learning control which is suggested to work with a certain consensus mechanism which appears to leave room for achieving cyber-physical security, robustness and performance goals.

We present the first spectroscopic measurements of the [O III] 5007 line in two z3.1 Lyα emitting galaxies (LAEs) using the new near-infrared instrument LUCIFER1 on the 8.4 m Large Binocular Telescope. We also describe the optical imaging and spectroscop