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1
Wasef, Shaik, and Hossein Fariborzi. "Theoretical Study of Field-Free Switching in PMA-MTJ Using Combined Injection of STT and SOT Currents." Micromachines 12, no. 11 (October 31, 2021): 1345. http://dx.doi.org/10.3390/mi12111345.
Повний текст джерелаАнотація:
Field-free switching in perpendicular magnetic tunnel junctions (P-MTJs) can be achieved by combined injection of spin-transfer torque (STT) and spin-orbit torque (SOT) currents. In this paper, we derived the relationship between the STT and SOT critical current densities under combined injection. We included the damping–like torque (DLT) and field-like torque (FLT) components of both the STT and SOT. The results were derived when the ratio of the FLT to the DLT component of the SOT was positive. We observed that the relationship between the critical SOT and STT current densities depended on the damping constant and the magnitude of the FLT component of the STT and the SOT current. We also noted that, unlike the FLT component of SOT, the magnitude and sign of the FLT component of STT did not have a significant effect on the STT and SOT current densities required for switching. The derived results agreed well with micromagnetic simulations. The results of this work can serve as a guideline to model and develop spintronic devices using a combined injection of STT and SOT currents.
2
Liu, Hong Shun, Ting Ting Lv, Ming Ming Han, Liang Zou, Li Zhang, and Qing Quan Li. "Close-Operation Overvoltage of No-Load Transmission Line with Fault Current Limiter." Applied Mechanics and Materials 672-674 (October 2014): 1373–79. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.1373.
Повний текст джерелаАнотація:
The comprehensive impacts of series resonance type fault current limiter (FCL) on power system need further investigation and verification. With regard to switching on 500kV EHV no-load transmission line, the instantaneous peak value, the free component oscillation frequency, the fundamental component amplitude and free component amplitude of terminal overvoltage waveform are simulated with and without installation of FCL considering different switching times. The relationship curves of free component oscillation period, the fundamental component amplitude and free component amplitude are gotten respectively by simulation results. The law of the influence of different fault current limiting reactance on terminal voltage of switching on no-load line is also summarized. The analysis results show that the installation of FCL is benefit for switching on no-load line.
3
NWOGU, OKEY G. "Interaction of finite-amplitude waves with vertically sheared current fields." Journal of Fluid Mechanics 627 (May 25, 2009): 179–213. http://dx.doi.org/10.1017/s0022112009005850.
Повний текст джерелаАнотація:
A computationally efficient numerical method is developed to investigate nonlinear interactions between steep surface gravity waves and depth-varying ocean currents. The free-surface boundary conditions are used to derive a coupled set of equations that are integrated in time for the evolution of the free-surface elevation and tangential component of the fluid velocity at the free surface. The vector form of Green's second identity is used to close the system of equations. The closure relationship is consistent with Helmholtz's decomposition of the velocity field into rotational and irrotational components. The rotational component of the flow field is given by the Biot–Savart integral, while the irrotational component is obtained from an integral of a mixed distribution of sources and vortices over the free surface. Wave-induced changes to the vorticity field are modelled using the vorticity transport equation. For weak currents, an explicit expression is derived for the wave-induced vorticity field in Fourier space that negates the need to numerically solve the vorticity transport equation. The computational efficiency of the numerical scheme is further improved by expanding the kernels of the boundary and volume integrals in the closure relationship as a power series in a wave steepness parameter and using the fast Fourier transform method to evaluate the leading-order contribution to the convolution integrals. This reduces the number of operations at each time step from O(N2) to O(NlogN) for the boundary integrals and O[(NM)2] to O(NlogN) for the volume integrals, where N is the number of horizontal grid points and M is the number of vertical layers, making the model an order of magnitude faster than traditional boundary/volume integral methods. The numerical model is used to investigate nonlinear wave–current interaction in depth-uniform current fields and the modulational instability of gravity waves in an exponentially sheared current in deep water. The numerical results demonstrate that the mean flow vorticity can significantly affect the growth rate of extreme waves in narrowband sea states.
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Wickenden, A. D., T. J. Jegla, R. Kaprielian, and P. H. Backx. "Regional contributions of Kv1.4,Kv4.2, andKv4.3 to transient outward K+ current in rat ventricle." American Journal of Physiology-Heart and Circulatory Physiology 276, no. 5 (May 1, 1999): H1599—H1607. http://dx.doi.org/10.1152/ajpheart.1999.276.5.h1599.
Повний текст джерелаАнотація:
The aim of the present study was to assess differences in transient outward potassium current ( I to) between the right ventricular free wall and the interventricular septum of the adult rat ventricle and to evaluate the relative contributions of Kv4.2, Kv4.3, and Kv1.4 to I to in these regions. The results show that I to is composed of both rapidly and slowly recovering components in the right wall and septum. The fast component had a significantly higher density in the right free wall than in the septum, whereas the slow component did not differ between the two sites. Kv4.2mRNA and protein levels were also highest in the right wall and correlated with I to density, whereas Kv4.3 was expressed uniformly in these regions. The kinetics of the rapidly recovering component of I to in myocytes was similar to that recorded in tsa-201 cells expressing Kv4.2 and Kv4.3 channels. Kv1.4 mRNA and protein expression correlated well with the density of the slowly recovering I to, whereas the recovery kinetics of the slow component were identical to Kv1.4 expressed in tsa-201 cells. In conclusion, expression of Kv1.4, Kv4.2, and Kv4.3 differs between regions in rat hearts. Regionally specific differences in the genetic composition of I to can account for the region-specific properties of this current.
5
Weimer, Daniel, and Thom Edwards. "Testing the electrodynamic method to derive height-integrated ionospheric conductances." Annales Geophysicae 39, no. 1 (January 14, 2021): 31–51. http://dx.doi.org/10.5194/angeo-39-31-2021.
Повний текст джерелаАнотація:
Abstract. We have used empirical models for electric potentials and the magnetic fields both in space and on the ground to obtain maps of the height-integrated Pedersen and Hall ionospheric conductivities at high latitudes. This calculation required use of both “curl-free” and “divergence-free” components of the ionospheric currents, with the former obtained from magnetic fields that are used in a model of the field-aligned currents. The second component is from the equivalent current, usually associated with Hall currents, derived from the ground-level magnetic field. Conductances were calculated for varying combinations of the interplanetary magnetic field (IMF) magnitude and orientation angle, as well as the dipole tilt angle. The results show that reversing the sign of the Y component of the IMF produces substantially different conductivity patterns. The Hall conductivities are largest on the dawn side in the upward, Region 2 field-aligned currents. Low electric field strengths in the Harang discontinuity lead to inconclusive results near midnight. Calculations of the Joule heating, obtained from the electric field and both components of the ionospheric current, are compared with the Poynting flux in space. The maps show some differences, while their integrated totals match to within 1 %. Some of the Poynting flux that enters the polar cap is dissipated as Joule heating within the auroral ovals, where the conductivity is greater.
6
Syms, R. R. A. "Principles of free-space optical microelectromechanical systems." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 1 (January 1, 2008): 1–18. http://dx.doi.org/10.1243/09544062jmes662.
Повний текст джерелаАнотація:
Optical microelectromechanical systems (MEMS) combine miniature optical components with precision fixtures, elastic suspensions, and microactuators, and allow complex functionality at low cost. However, the effect of the bounded nature of the beams propagating through the system on design is profound. The current paper reviews the fundamental consequences. Using a Gaussian beam formulation, models of guided modes in gradient index media, bounded beams and imaging components are constructed. Propagation algorithms are described. The alignment tolerances for common component trains such as fibre-to-fibre and beam-to-fibre connections are derived, limits on the curvature of reflecting surfaces are established, the scaling laws of free-space optical MEMS are presented and the effect of beam size on filter performance is clarified. Examples such as variable optical attenuators, optical cross-connect switches, filters and tunable lasers are discussed.
7
David, J. A., and R. M. Pitman. "Calcium and potassium currents in the fast coxal depressor motor neuron of the cockroach Periplaneta americana." Journal of Neurophysiology 74, no. 5 (November 1, 1995): 2043–50. http://dx.doi.org/10.1152/jn.1995.74.5.2043.
Повний текст джерелаАнотація:
1. Membrane currents have been examined in the cell body of the fast coxal depressor motor neuron (Df) of the cockroach Periplaneta americana with the use of two-electrode voltage clamp. 2. Most of the outward current induced by membrane depolarizations to between -40 and +80 mV was carried by K+ because it was blocked by external tetraethylammonium+ (TEA+; 20 mM) and internal Cs+. 3. Over the potential range -20 to +80 mV, a large proportion of this TEA+/Cs(+)-sensitive K+ current consisted of two temporal components, a transient outward current (IKtrans) and a sustained outward current (IKsus). IKtrans and a large proportion of IKsus appeared to be calcium-activated potassium currents (IK,Ca,trans and IK,Ca,sus, respectively) because these were suppressed by injecting ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), removing Ca2+ from the saline or replacing Ca2+ with Ba2+. After suppression of IK,Ca by internal EGTA or Ca(2+)-free saline, membrane depolarizations positive to -40 mV induced voltage-dependent outward currents (IK,V), which consisted of single-component outward relaxations. 4. When outward currents were blocked by external TEA+/internal Cs+, a voltage-dependent inward current consisting of a transient and a sustained component was observed over the potential range -40 to +40 mV. Both components of this inward current appeared to be carried by Ca2+ because they were blocked by external Cd2+ (1 mM), verapamil (0.1 mM), nifedipine (0.1 mM), or diltiazem (0.1 mM). 5. Both the transient component of the calcium current (ICa,trans) and the sustained component (ICa,sus) were maximal at 0 mV and present when Ca2+ in the saline were replaced by Ba2+. The inactivation of ICa,trans is voltage dependent, the rate of inactivation increasing with membrane depolarization. 6. The current-voltage relationships of Ca2+ currents differed from those of calcium-activated K+ currents. It is proposed that the discrepancy between these current-voltage relationships arises from the rapidity with which IK,Ca is saturated by Ca2+ entering through voltage-dependent channels and because the apparent reversal potential for ICa is not at ECa. 7. Although the similarity in the shape of IK,Ca and ICa might suggest that the time course of IK,Ca is determined by the kinetics of ICa, this appears unlikely in view of the rapid saturation of IK,Ca by Ca2+, which considerably outlasts the period of Ca2+ influx.
8
Hume, J. R. "Component of whole cell Ca current due to electrogenic Na-Ca-exchange in cardiac myocytes." American Journal of Physiology-Heart and Circulatory Physiology 252, no. 3 (March 1, 1987): H666—H670. http://dx.doi.org/10.1152/ajpheart.1987.252.3.h666.
Повний текст джерелаАнотація:
A carrier mechanism that mediates an exchange of Na+ for Ca2+ across the cell membrane is believed to be an important regulator of intracellular Ca2+ and therefore the contractile strength of the heart. Considerable evidence indicates that there is an unequal transfer of electrical charge during this exchange which implies that the carrier may contribute substantially to the net flow of ionic current across the sarcolemmal membrane. To detect such a component of current, nondialyzed single frog atrial cells were transiently Ca2+-loaded by augmenting Ca2+ entry through membrane Ca2+ channels by exposure to either the beta-adrenergic agonist, isoproterenol, or to BAY K 8644, a Ca2+ channel agonist. A direct comparison of whole-cell Ca2+ currents during exposure to these compounds in Na+-containing and Na+-free solutions revealed the existence of an additional component of inward current in Na+-containing solutions which temporally overlaps with Ca2+ channel-mediated currents. The dependence of this component of inward current on intracellular Ca2+ and extracellular Na+ and its resemblance to previously characterized carrier-mediated currents (creep currents) in this preparation suggest that it is associated with electrogenic Na+-Ca2+-exchange activity. These experiments support earlier predictions that under some conditions a component of the slow inward current in the heart may actually represent Ca2+ efflux mediated by an electrogenic Na+-Ca2+-exchange carrier.
9
Tateishi, N., D. K. Kim, and N. Akaike. "Acetylcholine-activated ionic currents in parasympathetic neurons of bullfrog heart." Journal of Neurophysiology 63, no. 5 (May 1, 1990): 1052–59. http://dx.doi.org/10.1152/jn.1990.63.5.1052.
Повний текст джерелаАнотація:
1. The electrical and pharmacologic properties of acetylcholine (ACh)-induced current (IACh) were studied in the parasympathetic neurons isolated from bullfrog heart with the use of the concentration-clamp technique, which allows intracellular perfusion and rapid change of external solution within 2 ms under the single-electrode voltage-clamp condition. 2. The IACh consisted of an initial transient peak component and a successive steady-state plateau component. Both currents increased in a sigmoidal fashion with increasing ACh concentration. The dissociation constant (Kd value) and the Hill coefficient for each component were 2.2 X 10(-5) M and 1.6, respectively. 3. In the K(+)-free solution, the reversal potential (EACh) of IACh was close to the Na+ equilibrium potential (ENa). The current-voltage (I-V) relation showed inward rectification at positive potentials. 4. Nicotine mimicked only the peak component of IACh. However both peak and steady-state components were blocked nonselectively by the nicotinic blockers d-tubocurarine and hexamethonium. 5. Carbamylcholine (CCh) mimicked the steady-state component of IACh. The steady-state component was selectively inhibited by atropine at concentrations 1,000 times lower than that required for inhibition of the peak component. The steady state was blocked equally by either pirenzepine (M1 blocker) or AF-DX-116 (M2 blocker). 6. It was concluded that the IACh consisted of a peak component having double exponential activation and inactivation, mediated through the nicotinic actions, and a steady-state component having no inactivation, mediated through the muscarinic action.
10
Teles, Maria João, António Pires-Silva, and Michel Benoit. "THE INFLUENCE OF THE TURBULENCE CLOSURE MODEL ON WAVE-CURRENT INTERACTION MODELING AT A LOCAL SCALE AT A LOCAL SCALE." Coastal Engineering Proceedings 1, no. 33 (October 18, 2012): 64. http://dx.doi.org/10.9753/icce.v33.waves.64.
Повний текст джерелаАнотація:
An advanced CFD solver based on the RANS (Reynolds Averaged Navier-Stokes) equations is used to evaluate wave-current interactions through numerical simulations of combined wave-current free surface turbulent flows. The repercussions of various schemes for modeling turbulence effects is addressed with a special attention to the exchanges and fluxes of momentum and energy between the mean flow components and the wave (oscillatory) component. Numerical simulations are compared with experimental data from Klopman (1994).
11
Ridgway, C., E. R. Priest, and T. Amari. "Prominence sheets supported by constant-current force-free fields. II - Imposition of normal photospheric field component and prominence surface current." Astrophysical Journal 385 (February 1992): 718. http://dx.doi.org/10.1086/170978.
Повний текст джерела
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Honoré, E., M. M. Adamantidis, B. A. Dupuis, C. E. Challice, and P. Guilbault. "Calcium channels and excitation–contraction coupling in cardiac cells. II. A pharmacological study of the biphasic contraction in guinea-pig papillary muscle." Canadian Journal of Physiology and Pharmacology 65, no. 9 (September 1, 1987): 1832–39. http://dx.doi.org/10.1139/y87-285.
Повний текст джерелаАнотація:
Biphasic contractions were obtained in guinea-pig papillary muscle by inducing partial depolarization in K+-rich solution (17 mM) in the presence of 0.3 μM isoproterenol. Mn2+ ions inhibited the two components of contraction in a similar way. Nifedipine and particularly Cd2+ ions specifically inhibited the second component of contraction. Isoproterenol and BAY K 8644 markedly increased the amplitude of the second component (P2) of contraction. Nevertheless, a moderate positive inotropic effect of isoproterenol was found on the first component (P1) of contraction when excitability was restored by 0.2 mM Ba instead of isoproterenol. Acetylcholine and hypoxia decreased the amplitude of the second component of contraction to a greater extent. In the presence of digoxin or Na+-free solution, P1was strongly increased. When sarcoplasmic reticular function was hindered by 1 mM caffeine or in the presence of Ca2+-free Sr2+ solution, digoxin always induced a negative inotropic effect on P2. Inversely in these conditions the transient positive inotropic effect of Na+-free solution was strongly reduced. These results are consistent with the hypothesis that the late component of contraction is triggered by the slow inward Ca2+ current and that the early component is due to Ca2+ release from the sarcoplasmic reticulum.
13
He, Guo, Chao Jie Zhang, Guang Hui Chang, and Shu Hai Liang. "Testing Analog Circuits by PCA of Power Supply Current." Applied Mechanics and Materials 157-158 (February 2012): 641–45. http://dx.doi.org/10.4028/www.scientific.net/amm.157-158.641.
Повний текст джерелаАнотація:
A method using principal component analysis (PCA) of dynamic power supply current was proposed for testing of analog circuits in this paper. The basic model of the proposed method and the general rule for analog fault detection were described in detail. At first, the principal component model of fault-free circuits was constructed. Then the circuits-under-test was compared with the principal component model to calculate the statistic for fault detection. The features of power supply current in both time and frequency domain were combined by PCA, and it could overcome the difficulty to determine threshold by empirical knowledge. The proposed method was applied to detect faults of the signal filtering and amplifying circuit, which is used in the ultrasonic liquid-level sensor. The results show that the power supply current contains information about the circuit’s faults, and can be used for fault detection of analog circuits by analyzing this signal.
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Liu, Y., and E. M. Lasater. "Calcium currents in turtle retinal ganglion cells. I. The properties of T- and L-type currents." Journal of Neurophysiology 71, no. 2 (February 1, 1994): 733–42. http://dx.doi.org/10.1152/jn.1994.71.2.733.
Повний текст джерелаАнотація:
1. Voltage-activated calcium currents from single, isolated turtle retinal ganglion cells were characterized with standard whole cell patch clamp techniques. Calcium current amplitude was increased with the use of 10 mM extracellular Ca2+, whereas sodium and potassium currents were pharmacologically suppressed. 2. A transient component, expressed in approximately 39% of the cells recorded from, closely resembled the T-type calcium current described previously in other tissues. This component activated at low voltages (around -50 mV from a holding potential of -70 mV) and inactivated with a time constant 10-30 ms at -20 mV; the inactivation was strongly voltage dependent. Substitution of Ca2+ with Ba2+ reduced this current in most cases or had no effect in some instances. Surprisingly, the transient calcium current was potentiated by Bay-K 8644 and inhibited by nifedipine in some of the ganglion cells tested. 3. A sustained component, which activated at between -20 and -10 mV from a holding potential of -70 mV, was found in all ganglion cells from which we recorded. This component was substantially larger when equimolar Ba2+ replaced Ca2+ as the charge carrier, and was sensitive to the dihydropyridine agonist Bay-K 8644 and the antagonist nifedipine. Thus the sustained current in turtle retinal ganglion cells was similar to the L-type calcium current described in chick DRG neurons. However, unlike the typical L-type current, this component in turtle ganglion cells showed an inactivation that was highly dependent on the intracellular free Ca2+ concentration but not the membrane potential. 4. Synthetic omega-conotoxin MVIIC selectively blocked the sustained calcium current while sparing the transient component. It could completely block the sustained current that was resistant to nifedipine in some cells. Thus there may exist several different high voltage-activated calcium channels in turtle retinal ganglion cells.
15
Hollywood, M. A., K. D. McCloskey, N. G. McHale, and K. D. Thornbury. "Characterization of outward K+currents in isolated smooth muscle cells from sheep urethra." American Journal of Physiology-Cell Physiology 279, no. 2 (August 1, 2000): C420—C428. http://dx.doi.org/10.1152/ajpcell.2000.279.2.c420.
Повний текст джерелаАнотація:
The perforated-patch technique was used to measure membrane currents in smooth muscle cells from sheep urethra. Depolarizing pulses evoked large transient outward currents and several components of sustained current. The transient current and a component of sustained current were blocked by iberiotoxin, penitrem A, and nifedipine but were unaffected by apamin or 4-aminopyridine, suggesting that they were mediated by large-conductance Ca2+-activated K+ (BK) channels. When the BK current was blocked by exposure to penitrem A (100 nM) and Ca2+-free bath solution, there remained a voltage-sensitive K+ current that was moderately sensitive to blockade with tetraethylammonium (TEA; half-maximal effective dose = 3.0 ± 0.8 mM) but not 4-aminopyridine. Penitrem A (100 nM) increased the spike amplitude and plateau potential in slow waves evoked in single cells, whereas addition of TEA (10 mM) further increased the plateau potential and duration. In conclusion, both Ca2+-activated and voltage-dependent K+currents were found in urethral myocytes. Both of these currents are capable of contributing to the slow wave in these cells, suggesting that they are likely to influence urethral tone under certain conditions.
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Marques, Ana C., Helena Dias, Sandro Matos, Bruno Sargaço, Ricardo Simoes, Aster De Schrijver, and João C. Bordado. "Polyurethane one-component foam formulation optimization for low free isocianate monomer content." Journal of Cellular Plastics 53, no. 2 (July 28, 2016): 167–79. http://dx.doi.org/10.1177/0021955x16639230.
Повний текст джерелаАнотація:
Recent changes in legislation have forced one-component foam producers to drop the amount of free monomeric isocyanate in their polyurethane systems. Also, it is required that commercial polyurethane aerosol cans exhibit at least one year of shelf life and polyurethane foams must be classified as B2 on the fire testing following DIN 4102. This paper reports on a systematic optimization study of polyurethane formulations dedicated to address these current industry requirements. A one-component foam system exhibiting simultaneously all of these parameters was achieved by reacting conventional diols, a relatively low-molecular weight monol (2-ethylhexanol), a flame retardant high-molecular weight monol (tris(bromoneopentyl)alcohol), a methylene diphenyl diisocyanate-based prepolymer (GreenAdduct 13), and a small amount of 2,4′-toluene diisocyanate. The use of monols allows producing prepolymers with low free methylene diphenyl diisocyanate by preventing chain extension and, therefore, avoiding extreme viscosity build-up. Toluene diisocyanate also promotes a lower viscosity inside the aerosol can, which enables the use of high enough quantities of high-molecular weight flame retardant monol to achieve a B2 fire test classification.
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Nurmi, Antti, and Matti Vornanen. "Electrophysiological properties of rainbow trout cardiac myocytes in serum-free primary culture." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 282, no. 4 (April 1, 2002): R1200—R1209. http://dx.doi.org/10.1152/ajpregu.00350.2001.
Повний текст джерелаАнотація:
A low-density primary culture of trout ventricular myocytes in serum-free growth medium was established and maintained for up to 10 days at 17°C. The myocytes retained their normal rod shaped morphology, capacitive surface area of the sarcolemma (SL), and contractile quiescence. However, sarcolemmal cation currents changed significantly, some permanently, some transiently, after 8–10 days of culture. TTX-sensitive sodium current ( I Na) and Ba2+-sensitive background inward rectifier potassium current ( I K1) were permanently depressed to 24–28% of their control density measured in freshly isolated myocytes. In contrast, L-type calcium current ( I Ca) was only transiently downregulated; after 2–3 days in culture, the density of the current was 32% of the control and recovered to the control value after 8–10 days in culture. The changes in membrane currents were reflected in the shape of the action potential (AP). After 2–3 days in culture, maximal overshoot potential and resting potential were significantly reduced, and the durations of the AP at 50 and 90% repolarization were significantly increased. These changes became significantly more pronounced after 8–10 days of culture, with the exception of AP duration at 50% repolarization level. The shortening of the early plateau phase may reflect an additional change to an outward current, presumably the rapid component of the delayed rectifier ( I Kr). Although the present findings indicate that fish cardiac myocytes can be maintained in serum-free primary culture for at least 10 days at 17°C, some but not all of the electrophysiological characteristics of the myocytes change markedly during culture. The changes in ion currents were not due to loss of sarcolemmal membrane and therefore are likely to represent altered expression of cation currents as an adaptive response to culture conditions.
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Smith, J. Torquil. "Conservative modeling of 3-D electromagnetic fields, Part I: Properties and error analysis." GEOPHYSICS 61, no. 5 (September 1996): 1308–18. http://dx.doi.org/10.1190/1.1444054.
Повний текст джерелаАнотація:
Conservation of electric current and magnetic flux can be explicitly enforced by modeling Maxwell’s equations on a staggered grid, where the different field components are sampled at points offset relative to each other. A staggered finite‐difference (SFD) approximation gives divergence‐free magnetic fields and electric currents ensuring good behavior at all periods. Comparisons of SFD solutions with 2-D quasi‐analytic solutions are very good (∼1% rms error). When a modeled region can be subdivided into uniform subdomains, comparison of analytic solutions and SFD approximations show that the greatest differences occur near the Nyquist wavenumbers; the SFD solutions do not attenuate in space as rapidly as the analytic solutions. The accuracy of a computed SFD solution can be estimated from its wavenumber content. For test cases the accuracy estimates are surprisingly close to the actual accuracies. Grid requirements for modeling short horizontal wavelength components of a solution seem more demanding than for modeling the infinite wavelength (plane‐wave) component: for 2% accuracy 4π samples are required per horizontal wavelength compared to two samples per skin depth for the plane‐wave component.
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Sammarco, Paolo, Chiang C. Mei, and Karsten Trulsen. "Nonlinear resonance of free surface waves in a current over a sinusoidal bottom: a numerical study." Journal of Fluid Mechanics 279 (November 25, 1994): 377–405. http://dx.doi.org/10.1017/s0022112094003940.
Повний текст джерелаАнотація:
We examine the free surface flow over a fixed bed covered by rigid sinusoidal dunes. The mean current velocity is near the critical value at which the linearized theory predicts unbounded response. By allowing transients we examine the instability of the steady and nonlinear solution of Mei (1969) and the possibility of chaos when the current has a small oscillatory component.
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Miura, Akira, Masahito Kawatani, and William C. De Groat. "Excitatory Synaptic Currents in Lumbosacral Parasympathetic Preganglionic Neurons Evoked by Stimulation of the Dorsal Commissure." Journal of Neurophysiology 89, no. 1 (January 1, 2003): 382–89. http://dx.doi.org/10.1152/jn.00180.2002.
Повний текст джерелаАнотація:
Excitatory pathways from the dorsal commissure (DCM) to L6–S1 parasympathetic preganglionic neurons (PGN) were examined using whole-cell patch-clamp recording techniques in spinal cord slices from neonatal rats. PGN were identified by retrograde axonal transport of a fluorescent dye injected into the intraperitoneal space. Excitatory postsynaptic currents (EPSCs) were evoked in PGN by stimulation of DCM in the presence of bicuculline methiodide (10 μM) and strychnine (1 μM) to block inhibitory pathways. Electrical stimulation of DCM evoked two types of inward currents. In the majority of PGN ( n = 66), currents (mean amplitude, 47.9 ± 4.7 pA) occurred at a short and relatively constant latency (3.8 ± 0.1 ms) and presumably represent monosynaptic EPSCs (Type 1). However, in other neurons ( n = 20), a different type of EPSC (Type 2) was noted, consisting of a fast monosynaptic component followed by a prolonged inward current with superimposed fast transients presumably representing excitatory inputs mediated by polysynaptic pathways. Type 1 EPSCs were pharmacologically dissected into two components. A fast component was blocked by 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 5μM) and a slowly decaying component was blocked by 2-amino-5-phosphonovalerate (APV, 50 μM). The fast component of Type 1 EPSCs had a linear current-voltage relationship and reversed at a membrane potential of −7.6 ± 1.3 mV ( n = 5). The fast component of Type 2 EPSCs was also blocked by 5 μM CNQX and the remaining slower component was blocked by 50 μM APV. When the DCM was stimulated in the presence of 50 μM APV, the time to peak and decay time constant in Type 1 EPSCs were 1.9 ± 0.2 and 4.1 ± 0.8 ms, respectively. Examination of the NMDA receptor-mediated component of the EPSCs in the presence of 5 μM CNQX revealed a current-voltage relationship that had a region of negative slope conductance (from −20 to −80 mV), which was abolished in Mg2+-free external solution. The time to peak and decay time constant of this component were 14.2 ± 2.0 and 91.0 ± 12.4 ms, respectively. Type 1 EPSCs in some PGN responded in an all-or-none manner and presumably represented unitary synaptic responses; whereas Type 2 EPSCs always exhibited a graded stimulus intensity–response relationship. Paired-pulse facilitation (50-ms interstimulus intervals; 141 ± 5.6% increase, n = 8) of EPSCs was observed. These results indicate that PGN receive monosynaptic and polysynaptic glutamatergic excitatory inputs from neurons and/or axonal pathways in the DCM.
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Hinderdael, Michaël, Zoé Jardon, Julien Ertveldt, and Patrick Guillaume. "Structural health monitoring through surface acoustic wave inspection deployed on capillaries embedded in additively manufactured components." MATEC Web of Conferences 349 (2021): 03010. http://dx.doi.org/10.1051/matecconf/202134903010.
Повний текст джерелаАнотація:
Surface Acoustic Wave inspection is a well-known non-destructive testing technique that receives considerable attention to become implemented as a Structural Health Monitoring system. The current work presents a novel approach to embed Surface Acoustic Wave-based Structural Health Monitoring technology inside additively manufactured components. A capillary network is to be integrated inside the component and Surface Acoustic Wave inspection is then deployed on the free capillary surface during the component’s operation to warn upcoming failures.
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Tylavsky, Frances, Timothy Lohman, Barbara A. Blunt, Dale A. Schoeller, Thomas Fuerst, Jane A. Cauley, Michael C. Nevitt, Marjolein Visser, and Tamara B. Harris. "QDR 4500A DXA overestimates fat-free mass compared with criterion methods." Journal of Applied Physiology 94, no. 3 (March 1, 2003): 959–65. http://dx.doi.org/10.1152/japplphysiol.00732.2002.
Повний текст джерелаАнотація:
This study evaluated the accuracy with which the dual-energy X-ray absorptiometer (Hologic QDR 4500A) measured fat-free mass (FFM), fat mass (FM), and hydration of FFM. In a study of 58 men and women (ages 70–79 yr), the QDR 4500A was found to provide a systematically higher estimate of FFM and lower estimate of FM than a four-component model of body composition. A correction factor from this study was developed and applied to two other samples ( n = 13 and 37). We found mean corrected levels of FFM and FM to be equivalent to that obtained by the four-component model or total body water. In addition, the hydration of the corrected FFM was closer to the established hydration level in adult samples and that obtained from the four-component model. These findings suggest that the current calibration of the fan-beam system of the Hologic QDR 4500A provides an overestimate of FFM and underestimate of FM compared with reference methods.
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Stoica, Alexandra Elena, Alexandru Mihai Grumezescu, Anca Oana Hermenean, Ecaterina Andronescu, and Bogdan Stefan Vasile. "Scar-Free Healing: Current Concepts and Future Perspectives." Nanomaterials 10, no. 11 (October 31, 2020): 2179. http://dx.doi.org/10.3390/nano10112179.
Повний текст джерелаАнотація:
Every year, millions of people develop scars due to skin injuries after trauma, surgery, or skin burns. From the beginning of wound healing development, scar hyperplasia, and prolonged healing time in wound healing have been severe problems. Based on the difference between adult and fetal wound healing processes, many promising therapies have been developed to decrease scar formation in skin wounds. Currently, there is no good or reliable therapy to cure or prevent scar formation. This work briefly reviews the engineering methods of scarless wound healing, focusing on regenerative biomaterials and different cytokines, growth factors, and extracellular components in regenerative wound healing to minimize skin damage cell types, and scar formation.
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Lacaz-Vieira, F., and W. Van Driessche. "Effect of mucosal halides on Ca(2+)-blockable currents through the skin of Rana ridibunda." American Journal of Physiology-Cell Physiology 261, no. 4 (October 1, 1991): C650—C657. http://dx.doi.org/10.1152/ajpcell.1991.261.4.c650.
Повний текст джерелаАнотація:
The present study deals with the interaction of mucosal anions with apical Ca(2+)-blockable cation channels of the skin of Rana ridibunda. The intracellular potential was depolarized by exposing the basolateral membranes to K2SO4 Ringer solution. The apical bathing medium consisted of nominal Ca(2+)-free K+ or Na+ solutions with SO4(2-), Cl-, Br-, or I- as the major anion. The effects of mucosal anion substitutions were studied by analyzing 1) the fluctuation in K+ current across the apical membrane driven by imposed transepithelial clamping potentials and 2) alterations of the transepithelial current (It) and conductance (Gt) as well as the Lorentzian parameters in response to anion substitution in the mucosal bathing solution. It and current noise spectra were recorded at different transepithelial potentials (Vt). A Lorentzian component was present in the power density spectrum when Vt was clamped at mucosa-positive voltages. Such noise components were never observed with mucosa-negative potentials. These findings suggest a rectifying behavior of the transepithelial cation currents. The Lorentzian noise component and the inward-oriented cation currents were depressed by the addition of micromolar concentrations of Ca2+ to the apical solutions as well as by replacing mucosal K+ or Na+ by N-methyl-D-glucamine. The Ca(2+)-blockable current and Lorentzian noise plateau (So) were gradually increased by raising Vt. Both parameters, as well as the corner frequency (fc), depended strongly on the major anion species in the apical solution; replacing mucosal SO4(2-) by one of the halides tested reduced fc and elevated So, It, and Gt considerably.
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Rodríguez-Chaves, Daniela, Vanessa Bagnarello-Madrigal, Javier Alpizar-Cordero, Alonso Calvo-Vargas, Maribel Cordero-Villalobos, Misael Chinchilla-Carmona, Idalia Valerio-Campos та Ronald Sánchez Porras. "Actividad in vitro anti-Leishmania (Trypanosomatidae) del epóxido trans-Z-α-bisaboleno y del Safrol, en frutos de Piper auritum (Piperaceae)". Revista de Biología Tropical 66, № 2 (24 травня 2018): 826. http://dx.doi.org/10.15517/rbt.v66i2.33412.
Повний текст джерелаАнотація:
Anti-Leishmania (Trypanosomatidae) activity of trans-Z-α-bisabolene epoxide and isolation of safrole, in fruits of Piper auritum (Piperaceae). The leishmaniosis disease incidence is high in tropical regions, and its current treatment has shown severe secondary effects. Considering this problem, many studies have focused on plants, looking for chemical components that have anti-leishmanial activity, and are free of adverse effects for human beings. The purpose of this work was to find a chemical component with this kind of activity in Piper auritum. In a phytochemical screening of this plant, we found some cumarins, terpens, triterpens and reducing sugars; and later, we identified the components trans-Z-α-bisabolene epoxide and Safrol. The first component presented a CI50 of 50.0 µg/mL of anti-Leishmania activity. The Safrol, which is the major component of the essential oils of this plant, did not show antiparasitic activity. These results are discussed considering treatment of leishmaniasis. Rev. Biol. Trop. 66(2): 826-835. Epub 2018 June 01.
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Himmel, H. M., R. L. Rasmusson, and H. C. Strauss. "Agonist-induced changes of [Ca2+]i and membrane currents in single bovine aortic endothelial cells." American Journal of Physiology-Cell Physiology 267, no. 5 (November 1, 1994): C1338—C1350. http://dx.doi.org/10.1152/ajpcell.1994.267.5.c1338.
Повний текст джерелаАнотація:
Cultured bovine aortic endothelial cells (BAECs) possess an inward rectifier K+ current (IK1), a Ca(2+)-activated K+ current, a nonselective cation current (INS), and a Ca(2+)-activated Cl- current; however, their relative roles remain to be established. In single BAECs, cytosolic free Ca2+ concentration ([Ca2+]i) [K5-fura 2 (50 microM), ratio 340/380 nm] was measured simultaneously with whole cell currents at 22 degrees C. Bradykinin (BK, 2 microM), ATP (10 microM), ionomycin (100 nM), or 2,5-di-(tert-butyl)-1,4-benzohydroquinone (10 microM) were used as agonists. In physiological salt solution (PSS), agonist exposure caused a rapid [Ca2+]i increase, followed by an increase in outward current (greater than -50 mV) and a smaller increase in inward current (greater than -80 mV). Chelation of [Ca2+]i with 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetraacetic acid attenuated agonist-induced [Ca2+]i and current responses. Inactivation of the cyclooxygenase pathway by acetylsalicyclic acid and ibuprofen (50 microM each) did not affect the BK-induced [Ca2+]i transient but abolished the current response. In K(+)-free solution, agonist-stimulated outward currents (at +50 mV) were 10 times smaller than in PSS and were consistent with the activation of both INS and a Cl- current. In Cl(-)-free solution, the outward current response following agonist exposure was virtually abolished; at the same time, a linear inward current component with a reversal potential near the equilibrium potential for Na+ was activated. The maximal amplitude of the agonist-induced outward current decreased with decreasing symmetrical Cl- concentrations. Our results suggest that 1) IKI is the dominant current in resting BAECs; 2) K+, Cl-, and nonselective cation conductances contribute to the agonist-induced current response; and 3) most of the agonist-induced activation of currents depends on increased [Ca2+]i and is sensitive to cyclooxygenase inhibitors.
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Roux, Michel J., Riccardo Olcese, Ligia Toro, Francisco Bezanilla, and Enrico Stefani. "Fast Inactivation in Shaker K+ Channels." Journal of General Physiology 111, no. 5 (May 1, 1998): 625–38. http://dx.doi.org/10.1085/jgp.111.5.625.
Повний текст джерелаАнотація:
Fast inactivating Shaker H4 potassium channels and nonconducting pore mutant Shaker H4 W434F channels have been used to correlate the installation and recovery of the fast inactivation of ionic current with changes in the kinetics of gating current known as “charge immobilization” (Armstrong, C.M., and F. Bezanilla. 1977. J. Gen. Physiol. 70:567–590.). Shaker H4 W434F gating currents are very similar to those of the conducting clone recorded in potassium-free solutions. This mutant channel allows the recording of the total gating charge return, even when returning from potentials that would largely inactivate conducting channels. As the depolarizing potential increased, the OFF gating currents decay phase at −90 mV return potential changed from a single fast component to at least two components, the slower requiring ∼200 ms for a full charge return. The charge immobilization onset and the ionic current decay have an identical time course. The recoveries of gating current (Shaker H4 W434F) and ionic current (Shaker H4) in 2 mM external potassium have at least two components. Both recoveries are similar at −120 and −90 mV. In contrast, at higher potentials (−70 and −50 mV), the gating charge recovers significantly more slowly than the ionic current. A model with a single inactivated state cannot account for all our data, which strongly support the existence of “parallel” inactivated states. In this model, a fraction of the charge can be recovered upon repolarization while the channel pore is occupied by the NH2-terminus region.
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Song, Yihang, Songfan Li, Chong Zhang, Shengyu Li, and Li Lu. "Rethinking Power Efficiency for Next-Generation Processor-Free Sensing Devices." Sensors 22, no. 8 (April 16, 2022): 3074. http://dx.doi.org/10.3390/s22083074.
Повний текст джерелаАнотація:
The last decade has seen significant advances in power optimization for IoT sensors. The conventional wisdom considers that if we reduce the power consumption of each component (e.g., processor, radio) into μW-level of power, the IoT sensors could achieve overall ultra-low power consumption. However, we show that this conventional wisdom is overturned, as bus communication can take significant power for exchanging data between each component. In this paper, we analyze the power efficiency of bus communication and ask whether it is possible to reduce the power consumption for bus communication. We observe that existing bus architectures in mainstream IoT devices can be classified into either push-pull or open-drain architecture. push-pull only adapts to unidirectional communication, whereas open-drain inherently fits for bidirectional communication which benefits simplifying bus topology and reducing hardware costs. However, open-drain consumes more power than push-pull due to the high leakage current consumption while communicating on the bus. We present Turbo, a novel approach introducing low power to the open-drain based buses by reducing the leakage current created on the bus. We instantiate Turbo on I2C bus and evaluate it with commercial off-the-shelf (COTS) sensors. The results show a 76.9% improvement in power efficiency in I2C communication.
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Raksha, N., Ju Sokolovskaya, E. Manzhaliy, D. Dobryanskiy, and O. Savchuk. "Estimation of antioxidant properties of experimental poly-component complexes." Bulletin of Taras Shevchenko National University of Kyiv. Series: Biology 82, no. 3 (2020): 63–66. http://dx.doi.org/10.17721/1728_2748.2020.82.63-66.
Повний текст джерелаАнотація:
The involvement of free radicals appears to be the feature of most human diseases. The general mechanism of cell damage involves the excessive uncontrolled production of reactive oxygen species resulting in the intensification of lipid peroxidation processes and damaging of macromolecules. These processes are generally accompanied by a decrease in the concentration and/or activity of natural antioxidants. Moreover, the exhaustion of the antioxidant capacity of the organism is among the key reasons leading to the development of pathological states. The maintenance of the prooxidant-antioxidant balance by the systematic use of products or dietary supplements, the components of which exhibit antioxidant activity, can be considered as a part of a strategy for the prevention and control of diseases associated with oxidative stress. The current work aims to study the free radical scavenging activity of two experimental poly-component complexes. Antioxidant properties of complexes were determined in experiments in vitro. The estimation of total antioxidant activity, nitric oxide, hydrogen peroxide radical, and superoxide anion scavenging activity was performed. The results revealed that both complexes have the potentials to prevent the formation of free radicals and can be used as agents with antioxidant properties. It was established that the effect of complex 1 and 2 is complex and first of all aimed at the prevention of the formation of dangerous free radicals by reducing the level of hydrogen peroxide. The additional mechanism involves the chelating of metal ions, in particular ferrous iron. The antioxidant ability exhibited by complex 1 was found to be higher than the total antioxidant activity of complex 2. Complex 1 was more effective in the ability to neutralize superoxide anion-radicals while complex 2 showed a high percentage inhibition of Fe2+-induced lipid peroxidation.
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Yi, Ai Hua, Wen Fang Li, Jun Du, and Song Lin Mu. "Preparation and Properties of Chrome-Free Colored Na3AlF6 Conversion Coating on Aluminum Alloy." Advanced Materials Research 490-495 (March 2012): 3527–30. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.3527.
Повний текст джерелаАнотація:
By adding tannic acid and film-forming accelerator in the treatment solution containing titanium and zirconium ions, a golden conversion coating on the surface of aluminum alloy was prepared. The main component and corrosion resistance of the conversion coating were characterized by means of EDS, SEM, XRD and electrochemical workstation. The conversion coating was golden and showed as uniform cubical crystal. results also showed that the main component of the conversion coating was Na3AlF6. In potentiodynamic polarization test, the corrosion current density of the aluminum alloy decreases to 0.083 A•cm-2 from 5.894 A•cm-2, which indicated an obvious improvement of corrosion resistance.
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Hromisin, Scott M., Russell W. Powers, and Leighton M. Myers. "Unsteady velocity measurements of model-scale supersonic exhaust jets in military-relevant configurations." International Journal of Aeroacoustics 17, no. 1-2 (February 24, 2018): 184–215. http://dx.doi.org/10.1177/1475472x17743634.
Повний текст джерелаАнотація:
Of the utmost importance is the need to better understand the high temperature, high velocity flow fields generated by military tactical aircraft during “run up” and take-off that gives rise to extremely hazardous conditions for personnel and equipment within the vicinity of the aircraft. The present study aims to fill the need for high frequency, two velocity component measurements throughout the flow fields produced by university-scale supersonic jets exhausting from nozzles in configurations relevant to practical, full-scale application. Specifically, this work focuses on studying the supersonic jets operating in two basic configurations: horizontal, free jets and jets impinging normal to a ground plane reminiscent of current short-takeoff and vertical landing aircraft. Experiments are conducted at nozzle operating conditions similar to those of full-scale aircraft. Both mean velocities and turbulence components are measured in both flow fields using a laser Doppler velocimeter. Axial components of the mean flow and turbulence are measured in the free jet. In the single impinging jet flow field two-component mean velocity and turbulence components are measured in the jet plume, impingement region, and outwash flow. Free jet velocity measurements show good consistency with 50% increase in jet Reynolds number. Turbulence intensities up to 15% of the mean jet exit velocity are observed at the nozzle exit plane. Laser Doppler measurements in the outwash of an impinging jet show turbulent fluctuations produce unsteady velocities well above the mean value. Two-component impinging jet unsteady velocity spectra show a distinct peak at the same frequency as the impingement tone observed in prior impinging jet acoustic field measurements.
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Yuan, X. J., W. F. Goldman, M. L. Tod, L. J. Rubin, and M. P. Blaustein. "Ionic currents in rat pulmonary and mesenteric arterial myocytes in primary culture and subculture." American Journal of Physiology-Lung Cellular and Molecular Physiology 264, no. 2 (February 1, 1993): L107—L115. http://dx.doi.org/10.1152/ajplung.1993.264.2.l107.
Повний текст джерелаАнотація:
The electrophysiological properties of cultured single vascular smooth muscle (VSM) cells from rat pulmonary (PA) and mesenteric (MA) arteries were studied using the whole cell patch-clamp technique. Cells were studied at 3–7 days as primary cultures, or were replated after 10–20 days and subcultured for 2–5 days. In the standard physiological bath solution (containing 1.8 mM Ca2+), and with 125 mM K+ + 10 mM ethylene glycol-bis(beta-aminoethyl ether)- N,N,N',N'-tetraacetic acid (EGTA)-filled pipettes, both PA and MA primary cultured cells had high input resistances (mean = 2-3 G omega) and resting membrane potentials of about -40 mV. The cells were clamped at a holding potential of -70 mV. Depolarization to -20 mV or more evoked a transient inward current (Iin) that was eliminated in Ca(2+)-free bath solution; this indicates that Iin was carried by Ca2+. Iin was substantially smaller in subcultured cells from both PA and MA. Depolarization also activated three components of outward current (Iout) in primary cultured PA and MA cells: a rapidly inactivating transient component (Irt), a slowly inactivating transient component (Ist), and a steady-state (noninactivating) component (Iss). All three components of Iout were inhibited to varying degrees by 5 mM 4-aminopyridine and were eliminated by replacing intracellular K+ with Cs+, but were only minimally affected by removal of extracellular Ca2+. These results suggest that this Iout was carried by K+ and was voltage gated. Little external Ca(2+)-dependent Iout was observed under these conditions, but a substantial Ca(2+)-dependent component was seen when the EGTA concentration in the pipettes was reduced to 0.1 mM.(ABSTRACT TRUNCATED AT 250 WORDS)
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Jepsen, D. C., and B. L. N. Kennett. "Three-component analysis of regional seismograms." Bulletin of the Seismological Society of America 80, no. 6B (December 1, 1990): 2032–52. http://dx.doi.org/10.1785/bssa08006b2032.
Повний текст джерелаАнотація:
Abstract Both phased array techniques for single-component sensors and vectorial analysis of three-component recordings can provide estimates of the azimuth and slowness of seismic phases. However, a combination of these approaches provides a more powerful tool to estimate the propagation characteristics of different seismic phases at regional distances. Conventional approaches to the analysis of three-component seismic records endeavor to exploit the apparent angles of propagation in horizontal and vertical planes as well as the polarization of the waves. The basic assumption is that for a given time window there is a dominant wavetype (e.g., a P wave) traveling in a particular direction arriving at the seismic station. By testing a range of characteristics of the three-component records, a set of rules can be established for classifying much of the seismogram in terms of wavetype and direction. It is, however, difficult to recognize SH waves in the presence of other wavetypes. Problems also arise when more than one signal (in either wavetype or direction) arrive in the same window. The stability and robustness of the classification scheme is much improved when records from an array of three-component sensors are combined. For a set of three-component instruments forming part of a larger array, it is possible to estimate the slowness and azimuth of arrivals from the main array and then extract the relative proportions of the current P-, SV-, and SH-wave contributions to the seismogram. This form of wavetype decomposition depends on a model of near-surface propagation. A convenient choice for hard-rock sites is to include just the effect of the free surface, which generates a frequency-independent operation on the three-component seismograms and which is not very sensitive to surface velocities. This approach generates good estimates of the character of the S wavefield, because the phase distortion of SV induced by the free surface can be removed. The method has been successfully applied to regional seismograms recorded at the medium aperture Warramunga array in northern Australia, and the two small arrays NORESS and ARCESS in Norway, which were designed for studies of regional phases. The new wavefield decomposition scheme provides results in which the relative proportions of P, SV, and SH waves as a function of time can be compared without the distortion imposed by free surface amplification. Such information can provide a useful adjunct to existing measures of signal character used in source discrimination.
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Fernau, Henning, Lakshmanan Kuppusamy, and Indhumathi Raman. "On describing the regular closure of the linear languages with graph-controlled insertion-deletion systems." RAIRO - Theoretical Informatics and Applications 52, no. 1 (January 2018): 1–21. http://dx.doi.org/10.1051/ita/2018005.
Повний текст джерелаАнотація:
A graph-controlled insertion-deletion (GCID) system has several components and each component contains some insertion-deletion rules. A transition is performed by any applicable rule in the current component on a string and the resultant string is then moved to the target component specified in the rule. The language of the system is the set of all terminal strings collected in the final component. When resources are very limited (especially, when deletion is demanded to be context-free and insertion to be one-sided only), then GCID systems are not known to describe the class of recursively enumerable languages. Hence, it becomes interesting to explore the descriptional complexity of such GCID systems of small sizes with respect to language classes below RE and even below CF. To this end, we consider so-called closure classes of linear languages defined over the operations concatenation, Kleene star and union. We show that whenever GCID systems (with certain syntactical restrictions) describe all linear languages (LIN) with t components, we can extend this to GCID systems with just one more component to describe, for instance, the concatenation of two languages from the language family that can be described as the Kleene closure of linear languages. With further addition of one more component, we can extend the construction to GCID systems that describe the regular closure of LIN.
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Grover, Anita, Jeffrey Teigler, Emily Radomile, Shawn Rose, Ted Yednock, Sanjay Keswani, and Henk-Andre Kroon. "Safety, Tolerability, and Clinical Pharmacology of ANX009, an Inhibitory Antibody Fab Fragment Against C1q, Administered Subcutaneously to Healthy Volunteers." Blood 138, Supplement 1 (November 5, 2021): 3166. http://dx.doi.org/10.1182/blood-2021-153289.
Повний текст джерелаАнотація:
Abstract Certain autoantibodies that bind to tissue antigens or that deposit in tissues as a component of immune complexes can activate the classical complement cascade, leading to inflammation and tissue damage. As the initiating molecule of the classical complement cascade, C1q is an attractive target for preventing complement activation and its multiple tissue-damaging effects. ANX009 is an antigen binding fragment (Fab) of a humanized antibody against C1q that inhibits C1q substrate interactions and fully blocks activation of all downstream classical complement components. While inhibiting the classical cascade, ANX009 leaves the lectin and alternative complement pathways intact for their normal immune functions. ANX009 is formulated for subcutaneous (SC) administration and is designed for treatment of blood-based and vascular antibody-mediated autoimmune diseases, such as autoimmune hemolytic anemia (AIHA) and lupus nephritis, where complement activation is a key component of disease pathology. A phase 1 first-in-human single ascending dose (SAD) and multiple ascending dose (MAD) study of ANX009 with subcutaneous administration was conducted in 48 healthy volunteers (NCT04535752). Four SAD cohorts were enrolled followed by two MAD cohorts evaluating daily dosing for 7 days or twice weekly dosing x 4 doses. Each cohort had eight participants randomized in a 6:2 active:placebo ratio. Safety and tolerability were assessed, along with serum pharmacokinetics (unbound drug), pharmacodynamics (unbound C1q target), and an ex vivo measure of C1q activity (CH 50 hemolysis of antibody-sensitized sheep red blood cells). All dose levels were well-tolerated. No drug-related safety signals, dose-limiting toxicities, serious adverse events, or adverse events leading to discontinuations were observed. Mild, transient, local injection site reactions were observed. A clear dose-response relationship was observed in SAD cohorts. Negligible reduction in free C1q was observed in the two lowest dose cohorts. A maximum mean reduction in free C1q of 80% was observed at 48 hours post-dose at the third dose level, and full reduction of free C1q through 72 hours was observed at the highest dose level. Similarly, full reduction of free C1q was observed in the MAD cohort with daily dosing as well as in the second MAD cohort with twice weekly dosing. Full reduction of C1q was maintained for 4 days following the last dose in the second MAD cohort. Ex vivo functional activity of C1q was completely inhibited in close correspondence with free C1q levels. Combined safety, tolerability, and clinical pharmacology results from this phase 1 study support advancement of ANX009 to studies in patients with complement-mediated autoimmune disorders. Disclosures Grover: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Teigler: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Radomile: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Rose: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Yednock: Annexon Inc: Current Employment, Current equity holder in publicly-traded company. Keswani: Annexon Inc: Current Employment, Current equity holder in publicly-traded company.
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Kleene, S. J., and R. Y. Pun. "Persistence of the olfactory receptor current in a wide variety of extracellular environments." Journal of Neurophysiology 75, no. 4 (April 1, 1996): 1386–91. http://dx.doi.org/10.1152/jn.1996.75.4.1386.
Повний текст джерелаАнотація:
We measured the current activated by cytoplasmic adenosine 3':5'-cyclic monophosphate (cAMP) in olfactory cilia from the frog Rana pipiens. The odorant-induced current in frog olfactory receptor neurons was also measured for comparison. In both cases, recordings were performed near the neuronal resting potential in a variety of extracellular bath solutions. 2. In Ca(2+)-free baths, cAMP activated an inward current in excised olfactory cilia that was carried entirely by cations. As extracellular Ca2+ was increased, the cationic current decreased while a second current, carried by C1-, increased. Total cAMP-activated current decreased with increasing extracellular CA2+. When external Na+ but not Ca2+ was eliminated, only the C1- component of the current persisted. When external Na+ and Ca2+ were both removed, there was no cAMP-activated current. 3. In receptor neurons, the total odorant-induced receptor current varied in a similar way with the extracellular ionic environment. Under conditions favoring the anionic receptor current, the response amplitude decreased and the latency increased. 4. It is known that olfactory receptor currents persist in a wide variety of extracellular environments. This persistence can be sufficiently explained by the balance between cationic and anionic currents demonstrated here.
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Zhang, Xueyuan, Yuhuan Ji, Jinzhi Liu, Ji Liu, Chunlei Li, Laixin Wang, Min Meng, and Limei Zhao. "Regulated bioanalysis of liposomal amphotericin B to support pharmacokinetic studies of liposomal drugs." Bioanalysis 14, no. 7 (April 2022): 421–39. http://dx.doi.org/10.4155/bio-2021-0281.
Повний текст джерелаАнотація:
Background: Because of the delicate nature of liposomes, bioanalysis of free and liposomal-encapsulated drugs is among the most challenging assays to perform. Current regulatory guidance for bioanalysis is not sufficient to address the complexity of this particular formulation. Method & results: Three individual LC–MS/MS methods to quantify free amphotericin B (10–3000 ng/ml) and encapsulated amphotericin B (100–50,000 ng/ml) in pretreated human plasma and total amphotericin B (100–50,000 ng/ml) in human plasma were fully validated and applied to a bioequivalence study. The acceptance criteria and experimental design of additional validation tests using cross quality control were carefully deliberated a priori and included in the sample analysis as well. Discussion: Additional validation tests are necessary to demonstrate that the measured concentration of the intended component is accurate and free of interference from other coexisting components in the sample. These practices can be used as guidance for future liposomal drug method validation.
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Bestman, A. R. "Unsteady low Reynolds number flow in a heated tube of slowly varying section." Journal of the Australian Mathematical Society. Series B. Applied Mathematics 30, no. 2 (October 1988): 179–202. http://dx.doi.org/10.1017/s0334270000006147.
Повний текст джерелаАнотація:
AbstractFluid motion established by an oscillatory pressure gradient superimposed on a mean, in a tube of slowly varying section, is studied when the temperature of the tube wall varies with axial distance. Particular attention is focussed on the mean flow and steady streaming components of the oscillatory flow of higher approximation. For the velocity components, the axial component takes the pride of place, since this component is responsible for convection of nutrients to various parts of the body of a mammal in systematic circulation. A salient point in the paper concerns consequences of free convection currents at a constriction (stenosis).
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Shimizu, Takahiro, Takahiro Iehara, Kaori Sato, Takuto Fujii, Hideki Sakai, and Yasunobu Okada. "TMEM16F is a component of a Ca2+-activated Cl− channel but not a volume-sensitive outwardly rectifying Cl− channel." American Journal of Physiology-Cell Physiology 304, no. 8 (April 15, 2013): C748—C759. http://dx.doi.org/10.1152/ajpcell.00228.2012.
Повний текст джерелаАнотація:
TMEM16 (transmembrane protein 16) proteins, which possess eight putative transmembrane domains with intracellular NH2- and COOH-terminal tails, are thought to comprise a Cl− channel family. The function of TMEM16F, a member of the TMEM16 family, has been greatly controversial. In the present study, we performed whole cell patch-clamp recordings to investigate the function of human TMEM16F. In TMEM16F-transfected HEK293T cells but not TMEM16K- and mock-transfected cells, activation of membrane currents with strong outward rectification was found to be induced by application of a Ca2+ ionophore, ionomycin, or by an increase in the intracellular free Ca2+ concentration. The free Ca2+ concentration for half-maximal activation of TMEM16F currents was 9.6 μM, which is distinctly higher than that for TMEM16A/B currents. The outwardly rectifying current-voltage relationship for TMEM16F currents was not changed by an increase in the intracellular Ca2+ level, in contrast to TMEM16A/B currents. The Ca2+-activated TMEM16F currents were anion selective, because replacing Cl− with aspartate− in the bathing solution without changing cation concentrations caused a positive shift of the reversal potential. The anion selectivity sequence of the TMEM16F channel was I− > Br− > Cl− > F− > aspartate−. Niflumic acid, a Ca2+-activated Cl− channel blocker, inhibited the TMEM16F-dependent Cl− currents. Neither overexpression nor knockdown of TMEM16F affected volume-sensitive outwardly rectifying Cl− channel (VSOR) currents activated by osmotic swelling or apoptotic stimulation. These results demonstrate that human TMEM16F is an essential component of a Ca2+-activated Cl− channel with a Ca2+ sensitivity that is distinct from that of TMEM16A/B and that it is not related to VSOR activity.
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Peluffo, R. Daniel, José M. Argüello, Jerry B Lingrel, and Joshua R. Berlin. "Electrogenic Sodium–Sodium Exchange Carried Out by Na,k -Atpase Containing the Amino Acid Substitution Glu779ala." Journal of General Physiology 116, no. 1 (July 1, 2000): 61–74. http://dx.doi.org/10.1085/jgp.116.1.61.
Повний текст джерелаАнотація:
Na,K -ATPase containing the amino acid substitution glutamate to alanine at position 779 of the α subunit (Glu779Ala) supports a high level of Na-ATPase and electrogenic Na+–Na+ exchange activityin the absence of K +. In microsomal preparations of Glu779Ala enzyme, the Na+ concentration for half maximal activation of Na-ATPase activity was 161 ± 14 mM (n = 3). Furthermore, enzyme activity with 800 mM Na+ was found to be similar in the presence and absence of 20 mM K +. These results showed that Na+, with low affinity, could stimulate enzyme turnover as effectively as K +. To gain further insight into the mechanism of this enzyme activity, HeLa cells expressing Glu779Ala enzyme were voltage clamped with patch electrodes containing 115 mM Na+ during superfusion in K +-free solutions. Electrogenic Na+–Na+ exchange was observed as an ouabain-inhibitable outward current whose amplitude was proportional to extracellular Na+ (Na+o) concentration. At all Na+o concentrations tested (3–148 mM), exchange current was maximal at negative membrane potentials (VM), but decreased as VM became more positive. Analyzing this current at each VM with a Hill equation showed that Na+–Na+ exchange had a high-affinity, low-capacity component with an apparent Na+o affinity at 0 mV (K 00.5) of 13.4 ± 0.6 mM and a low-affinity, high-capacity component with a K 00.5 of 120 ± 13 mM (n = 17). Both high- and low-affinity exchange components were VM dependent, dissipating 30 ± 3% and 82 ± 6% (n = 17) of the membrane dielectric, respectively. The low-affinity, but not the high-affinity exchange component was inhibited with 2 mM free ADP in the patch electrode solution. These results suggest that the high-affinity component of electrogenic Na+–Na+ exchange could be explained by Na+o acting as a low-affinity K + congener; however, the low-affinity component of electrogenic exchange appeared to be due to forward enzyme cycling activated by Na+o binding at a Na+-specific site deep in the membrane dielectric. A pseudo six-state model for the Na,K -ATPase was developed to simulate these data and the results of the accompanying paper (Peluffo, R.D., J.M. Argüello, and J.R. Berlin. 2000. J. Gen. Physiol. 116:47–59). This model showed that alterations in the kinetics of extracellular ion-dependent reactions alone could explain the effects of Glu779Ala substitution on the Na,K -ATPase.
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Krupp, J., and P. Feltz. "Excitatory postsynaptic currents and glutamate receptors in neonatal rat sympathetic preganglionic neurons in vitro." Journal of Neurophysiology 73, no. 4 (April 1, 1995): 1503–12. http://dx.doi.org/10.1152/jn.1995.73.4.1503.
Повний текст джерелаАнотація:
1. We obtained whole cell patch-clamp recordings from visually identified sympathetic preganglionic neurons (SPNs) in thin (200-300 microns) transverse spinal cord slices of neonatal rats (1-14 days postnatal). Exogenous application of glutamate (100 microM), N-methyl-D-aspartate (NMDA; 100 microM), kainate (100 microM), quisqualate (1 microM), and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA; 50 microM) induced inward currents at a holding potential of -30 mV. 2. Excitatory postsynaptic currents (EPSCs) were evoked by electrical stimulation either in the dorsal horn or the lateral funiculus. They reversed at 1.2 +/- 4.6 (SD) mV and could in most cases (49 of 51) be separated into two components. 3. In the presence of DL-2-amino-5-phosphonovalerate (10-40 microM) the current-voltage (I-V) relationship of the remaining EPSC was linear. When stimulated in the lateral funiculus, its rise time (10-90%) and the time constant of the monoexponential decay were 1.6 +/- 1.0 and 5.5 +/- 2.7 ms, respectively. By contrast, when stimulated in the dorsal horn, this component had a rise time (10-90%) of 3.0 +/- 0.8 ms and a decay time constant of 13.7 +/- 7.6 ms. 4. We studied the NMDA receptor-mediated component of the EPSCs after superfusion of 6-cyano-7-nitroquinoxaline-2,3-dione (5 microM). The I-V relationship of this component had a region of negative slope conductance between -30 and -80 mV, which was abolished in Mg(2+)-free saline. The rise time (10-90%) ranged from 3.3 to 9.5 ms and the decay was biexponential. Both decay time constants increased with depolarization. Mg(2+)-free saline reduced this voltage sensitivity. 5. At a membrane potential of -80 mV and in 1 mM extracellular Mg2+, the NMDA receptor-mediated component represented 74.8 +/- 11.2% of the total charge carried by the EPSCs evoked by stimulation in the dorsal horn. In contrast, when stimulated from the lateral funiculus, 28.9 +/- 18.9% of the total charge carried during the EPSC was mediated by the NMDA receptor-mediated component. The contribution of the NMDA receptor-mediated component increased in both cases with depolarization. In addition, in 2 of 18 SPNs the EPSC evoked in the dorsal horn was exclusively carried by NMDA receptors. 6. We conclude that L-glutamate or a related substance mediates the fast excitatory input onto SPNs. Viscerosomatic and supraspinal inputs form synapses with different topographical locations on the SPN.(ABSTRACT TRUNCATED AT 400 WORDS)
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Marx, Axel, Franz Ebert, and Nicolas Hachez. "Dispute Settlement for Labour Provisions in EU Free Trade Agreements: Rethinking Current Approaches." Politics and Governance 5, no. 4 (December 14, 2017): 49–59. http://dx.doi.org/10.17645/pag.v5i4.1070.
Повний текст джерелаАнотація:
While labour provisions have been inserted in a number of EU free trade agreements (FTAs), extant clauses are widely perceived as ineffective. This article argues that there is a need to rethink the dispute settlement mechanisms related to labour provisions if their effectiveness is to be increased. It proceeds in three steps. First, we look at the current state of the art of labour provisions in EU FTAs in terms of legal design and practice and argue that the current arrangements are ill-equipped to foster compliance with labour standards. Second, we explore avenues to enhance the design of FTA labour provisions by reconsidering basic elements of the dispute settlement structure. Examining US FTA labour provisions, we highlight the importance of a formal complaint mechanism, on the one hand, and the availability of economic sanctions, on the other. Based on a review of existing practice, we contend, however, that these elements alone are not sufficient to effectively enforce FTA labour provisions. We argue that for FTA labour provisions to be effective, the current state-to-state model of dispute settlement needs to be complemented by a third-party-state dimension and that, additionally, there are good reasons to consider a third party–third party dispute settlement component. We ground these reflections in experiences with already existing instruments in other areas, namely investor-state dispute settlement and voluntary sustainability standards. Thirdly, we discuss options to better connect the dispute settlement mechanisms of FTA labour provisions to other international instruments for labour standards protection with a view to creating synergies and avoiding fragmentation between the different regimes. The focus here is on the International Labour Organization’s supervisory mechanism and the framework of the OECD Guidelines for Multinational Enterprises.
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Saghir, M. Ziad, Seshasai Srinivasan, and Stefan Van Vaerenbergh. "Soret Measurement for Multi-Component Hydrocarbon Mixtures from Space Experiment Conducted Onboard FOTON M3 Unmanned Satellite." Applied Mechanics and Materials 225 (November 2012): 470–74. http://dx.doi.org/10.4028/www.scientific.net/amm.225.470.
Повний текст джерелаАнотація:
In an unprecedented experimental investigation, a binary, a ternary and a four-component hydrocarbon mixture at different pressure have been studied in a nearly convection free environment to understand the thermodiffusion process. Experimental investigations of the mixtures have been conducted in space onboard the spacecraft FOTON-M3. The experiment objective was to measure the thermodiffusion coefficient for multi-component hydrocarbon mixtures. Then the experimental results have also been used to test a thermodiffusion model that has been calibrated based on the results of previous experimental investigations. Results showed a good agreement with current theoretical results except for the four-component system where discrepancies were found and discussed.
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Harvey, R. D., and J. R. Hume. "Isoproterenol activates a chloride current, not the transient outward current, in rabbit ventricular myocytes." American Journal of Physiology-Cell Physiology 257, no. 6 (December 1, 1989): C1177—C1181. http://dx.doi.org/10.1152/ajpcell.1989.257.6.c1177.
Повний текст джерелаАнотація:
The effects of beta-adrenergic stimulation on the Ca2(+)-insensitive transient outward current (Ito) in rabbit ventricular myocytes were examined. Exposure to isoproterenol (ISO; 1 microM) activated a time-dependent current at positive membrane potentials. To determine whether this ISO-induced current was associated with Ito, sensitivity to the K+ channel antagonist, 3,4-diaminopyridine (DAP; 200 microM) was compared before and after exposure to ISO. The DAP-sensitive current was not enhanced by ISO, suggesting that the ISO-induced current was not a component of Ito. Ito and the ISO-induced current could also be dissociated by changing the membrane holding potential. Positive holding potentials, which produced significant inactivation of Ito, had little effect on the ISO-induced membrane current. Furthermore, the ISO-induced current could be observed when K+ was replaced by Cs+. The reversal potential of the ISO-induced current agreed with the predicted Cl- equilibrium potential, and exposure to Cl(-)-free extracellular solutions eliminated the response to ISO. Therefore, we conclude that ISO does not directly activate Ito in rabbit ventricular myocytes, but instead, activates a time-independent chloride current (ICl) similar to that recently described in guinea pig ventricular myocytes and shown to be regulated by adenylate cyclase (R. D. Harvey and J. R. Hume. Science Wash. DC 244: 983-985, 1989).
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GOLDING, MADELEINE J., and HERBERT E. HUPPERT. "The effect of confining impermeable boundaries on gravity currents in a porous medium." Journal of Fluid Mechanics 649 (April 13, 2010): 1–17. http://dx.doi.org/10.1017/s0022112009993223.
Повний текст джерелаАнотація:
The effect of confining boundaries on gravity currents in porous media is investigated theoretically and experimentally. Similarity solutions are derived for currents when the volume increases as tα in horizontal channels of uniform cross-section with boundary height b satisfying b ~ a|y/a|n, where y is the cross-channel coordinate and a is a length scale of the channel width. Experiments were carried out in V-shaped and semicircular channels for the case of gravity currents with constant volume (α=0) and constant flux (α=1). These showed generally good agreement with the theory.Typically, we find that the propagation of the current is well described by L ~ tc for some scalar c. We study the dependence of c on the time exponent of the volume of fluid in the current, α, and the geometry of the channel, parameterized by n. For all channel shapes, there exists a critical value of α, αc = 1/2, above which increasing n causes an increase in c and below which increasing n causes a decrease in c, where increasing n corresponds to opening up the channel boundary to the horizontal. The current height increases or decreases with respect to time depending on whether α is greater or less than αc. It is this fact, along with global mass conservation, which explains why varying the channel shape n affects the propagation rate c in different ways depending on α.We also consider channels inclined at an angle θ to the horizontal. When the slope of the channel is much greater than the slope of the free surface of the current, the component of gravity parallel to the slope dominates, causing the current to move with a constant velocity, Vf say, regardless of channel shape n and flux parameter α, in agreement with results for a two-dimensional gravity current obtained by Huppert & Woods (1995) and some initially axisymmetric gravity currents presented by Vella & Huppert (2006). If the effect of the component of gravity perpendicular to the channel may not be neglected, i.e. if the slopes of the channel and free surface of the current are comparable, we find that, in a frame moving with speed Vf, the form of the governing equation for the height of a current in an equivalent horizontal channel is recovered. We calculate that the height of a constant flux gravity current down an inclined channel will tend to a fixed depth, which is determined by the channel shape, n, and the physical properties of the fluid and rock. Experimental and numerical results for inclined V-shaped channels agree very well with this theory.
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SanFilipo, William A., Perry A. Eaton, and Gerald W. Hohmann. "The effect of a conductive half‐space on the transient electromagnetic response of a three‐dimensional body." GEOPHYSICS 50, no. 7 (July 1985): 1144–62. http://dx.doi.org/10.1190/1.1441988.
Повний текст джерелаАнотація:
The transient electromagnetic (TEM) response of a three‐dimensional (3-D) prism in a conductive half‐space is not always approximated well by three‐dimensional free‐space or two‐dimensional (2-D) conductive host models. The 3-D conductive host model is characterized by a complex interaction between inductive and current channeling effects. We numerically computed 3-D TEM responses using a time‐domain integral‐equation solution. Models consist of a vertical or horizontal prismatic conductor in conductive half‐space, energized by a rapid linear turn‐off of current in a rectangular loop. Current channeling, characterized by currents that flow through the body, is produced by charges which accumulate on the surface of the 3-D body and results in response profiles that can be much different in amplitude and shape than the corresponding response for the same body in free space, even after subtracting the half‐space response. Responses characterized by inductive (vortex) currents circulating within the body are similar to the response of the body in free space after subtracting the half‐space contribution. The difference between responses dominated by either channeled or vortex currents is subtle for vertical bodies but dramatic for horizontal bodies. Changing the conductivity of the host effects the relative importance of current channeling, the velocity and rate of decay of the primary (half‐space) electric field, and the build‐up of eddy currents in the body. As host conductivity increases, current channeling enhances the amplitude of the response of a vertical body and broadens the anomaly along the profile. For a horizontal body the shape of the anomaly is distorted from the free‐space anomaly by current channeling and is highly sensitive to the resistivity of the host. In the latter case, a 2-D response is similar to the 3-D response only if current channeling effects dominate over inductive effects. For models that are not greatly elongated, TEM responses are more sensitive to the conductivity of the body than galvanic (dc) responses, which saturate at a moderate resistivity contrast. Multicomponent data are preferable to vertical component data because in some cases the presence and location of the target are more easily resolved in the horizontal response and because the horizontal half‐space response decays more quickly than does the corresponding vertical response.
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Tellis, Raymond, and C. Khisty. "Social Cost Component of an Efficient Toll." Transportation Research Record: Journal of the Transportation Research Board 1576, no. 1 (January 1997): 140–46. http://dx.doi.org/10.3141/1576-18.
Повний текст джерелаАнотація:
Efficient tolls are tolls that ensure that the price paid by the roadway user is equal to the increment of social and private costs resulting from the highway use. Setting these tolls accomplishes an important objective: to correct the current practice that allows driving to be subsidized by government and nonusers. Without restrictions on vehicle ownership and unlimited access to the nation’s cost-free roadways, drivers do not pay for the social costs they generate. If motorists were required to pay their fair share of these social costs, travel decisions would probably be altered. Unwarranted trips, especially during peak hours, would be reduced because roadway space would be priced to accurately reflect the actual cost of driving. Beyond private costs, society is burdened with paying for infrastructure construction and maintenance, highway services, wasted fuel, pollution, accidents, and congestion costs from travel delays. The cost to society of automobile travel is assessed so that a charge can be made for the social cost component in computing what an efficient toll should be. It is found that the social cost fee during nonpeak travel comes to 0.67¢/vehicle-km (1.08¢/vehicle-mi). Travel during peak periods is far more expensive with the addition of congestion costs. The value of time drives up these costs, and the charges amount to 5.68¢/vehicle-km (9.14¢/vehicle-mi) for peak-period travel.
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McManus, Donald P., and Alex Loukas. "Current Status of Vaccines for Schistosomiasis." Clinical Microbiology Reviews 21, no. 1 (January 2008): 225–42. http://dx.doi.org/10.1128/cmr.00046-07.
Повний текст джерелаАнотація:
SUMMARY Schistosomiasis, caused by trematode blood flukes of the genus Schistosoma, is recognized as the most important human helminth infection in terms of morbidity and mortality. Infection follows direct contact with freshwater harboring free-swimming larval (cercaria) forms of the parasite. Despite the existence of the highly effective antischistosome drug praziquantel (PZQ), schistosomiasis is spreading into new areas, and although it is the cornerstone of current control programs, PZQ chemotherapy does have limitations. In particular, mass treatment does not prevent reinfection. Furthermore, there is increasing concern about the development of parasite resistance to PZQ. Consequently, vaccine strategies represent an essential component for the future control of schistosomiasis as an adjunct to chemotherapy. An improved understanding of the immune response to schistosome infection, both in animal models and in humans, suggests that development of a vaccine may be possible. This review considers aspects of antischistosome protective immunity that are important in the context of vaccine development. The current status in the development of vaccines against the African (Schistosoma mansoni and S. haematobium) and Asian (S. japonicum) schistosomes is then discussed, as are new approaches that may improve the efficacy of available vaccines and aid in the identification of new targets for immune attack.
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Romeo, Carmelo, and Giuseppe Santoro. "Free Radicals in Adolescent Varicocele Testis." Oxidative Medicine and Cellular Longevity 2014 (2014): 1–6. http://dx.doi.org/10.1155/2014/912878.
Повний текст джерелаАнотація:
We examine the relationship between the structure and function of the testis and the oxidative and nitrosative stress, determined by an excessive production of free radicals and/or decreased availability of antioxidant defenses, which occur in the testis of adolescents affected by varicocele. Moreover, the effects of surgical treatment on oxidative stress were provided. We conducted a PubMed and Medline search between 1980 and 2014 using “adolescent,” “varicocele,” “free radicals,” “oxidative and nitrosative stress,” “testis,” and “seminiferous tubules” as keywords. Cross-references were checked in each of the studies, and relevant articles were retrieved. We conclude that increased concentration of free radicals, generated by conditions of hypoxia, hyperthermia, and hormonal dysfunction observed in adolescent affected by varicocele, can harm germ cells directly or indirectly by influencing nonspermatogenic cells and basal lamina. With regard to few available data in current literature, further clinical trials on the pre- and postoperative ROS and RNS levels together with morphological studies of the cellular component of the testis are fundamental for complete comprehension of the role played by free radicals in the pathogenesis of adolescent varicocele and could justify its pharmacological treatment with antioxidants.
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Ling, Xiao, Chenhao Zhou, Lianqiao Yang, and Jianhua Zhang. "Research on Influence of Switching Angle on the Vibration of Switched Reluctance Motor." Applied Sciences 12, no. 9 (May 9, 2022): 4793. http://dx.doi.org/10.3390/app12094793.
Повний текст джерелаАнотація:
Switched Reluctance Motors (SRMs) have emerged as a viable competitor to other established electrical machines. Although SRMs have many advantages, such as a rare earth free nature, simple structure, high fault tolerance capability and low cost, vibration problems due to radial force variations is still a major issue faced by SRMs. Hence, aimed at the problem of vibration suppression for SRMs, this paper proposes a method that focuses on the influence of the change of the turn-on angle and turn-off angle on the vibration of the SRM under the switching angle control (SAC) strategy. Firstly, the influence of the turn-on and turn-off angles on the harmonic components of the current is analyzed in detail. Then, the vibration caused by the frequency of the harmonic components of the current and the natural frequency of the motor is mainly studied. The results show that the harmonic order affecting vibration is related to the rotational speed, and by analyzing the value of this harmonic order, the variation law of vibration with the switching angle can be obtained. When the turn-off angle is constant, the amplitudes of the current harmonic component and vibration first decrease and then increase with the increase of the turn-on angle. Additionally, when the turn-on angle is constant, the current harmonic and vibration show the tendency of periodic oscillation with the variation of the turn-off angle, and the oscillation period is related to the harmonic order. The combination of switching angles that minimizes the certain current harmonic component also minimizes vibration. The effectiveness of the variation law was verified on a 12/8 poles and 1.5 KW SRM drive system test bench, which provide a new perspective on vibration suppression of SRMs.