3,908 research outputs found
UNDERSTANDING TECHNOLOGY ADOPTION THROUGH SYSTEM DYNAMICS MODELING: IMPLICATIONS FOR AGRIBUSINESS MANAGEMENT
This work demonstrates the utility of sophisticated simulation tools in aiding agribusiness managers' decision making. The system dynamics model developed here provides insight into the use of such models to evaluate potential adoption rates and diffusion patterns of yield mapping and monitoring technologies. The model allows for comparative analyses of the possible effects of different profit assumptions on adoption and diffusion.Agribusiness, Research and Development/Tech Change/Emerging Technologies,
Ca2+-activated K+ Channels in Murine Endothelial Cells: Block by Intracellular Calcium and Magnesium
The intermediate (IKCa) and small (SKCa) conductance Ca2+-sensitive K+ channels in endothelial cells (ECs) modulate vascular diameter through regulation of EC membrane potential. However, contribution of IKCa and SKCa channels to membrane current and potential in native endothelial cells remains unclear. In freshly isolated endothelial cells from mouse aorta dialyzed with 3 Ī¼M free [Ca2+]i and 1 mM free [Mg2+]i, membrane currents reversed at the potassium equilibrium potential and exhibited an inward rectification at positive membrane potentials. Blockers of large-conductance, Ca2+-sensitive potassium (BKCa) and strong inward rectifier potassium (Kir) channels did not affect the membrane current. However, blockers of IKCa channels, charybdotoxin (ChTX), and of SKCa channels, apamin (Ap), significantly reduced the whole-cell current. Although IKCa and SKCa channels are intrinsically voltage independent, ChTX- and Ap-sensitive currents decreased steeply with membrane potential depolarization. Removal of intracellular Mg2+ significantly increased these currents. Moreover, concomitant reduction of the [Ca2+]i to 1 Ī¼M caused an additional increase in ChTX- and Ap-sensitive currents so that the currents exhibited theoretical outward rectification. Block of IKCa and SKCa channels caused a significant endothelial membrane potential depolarization (ā11 mV) and decrease in [Ca2+]i in mesenteric arteries in the absence of an agonist. These results indicate that [Ca2+]i can both activate and block IKCa and SKCa channels in endothelial cells, and that these channels regulate the resting membrane potential and intracellular calcium in native endothelium
Enabling I/O Automata Using Omniscient Archetypes
Many cyberinformaticians would agree that, had it not been for IPv6, the technical unification of digital-to-analog converters and Byzantine fault tolerance might never have occurred. Given the trends in constant-time theory, hackers worldwide famously note the study of randomized algorithms, which embodies the confirmed principles of cryptography. In our research we describe new game-theoretic archetypes (Sinner), showing that Byzantine fault toler- ance and the producer-consumer problem are mostly incompatible. Even though such a hypothesis might seem perverse, it fell in line with our expectations
On the Correlation of Torque and Luminosity in GX 1+4
Over five years of daily hard X-ray (>20 keV) monitoring of the 2-min
accretion-powered pulsar GX 1+4 with the Compton Gamma Ray Observatory/BATSE
large-area detectors has found nearly continuous rapid spin-down, interrupted
by a bright 200-d spin-up episode. During spin-down, the torque becomes more
negative as the luminosity increases (assuming that the 20-60 keV pulsed flux
traces bolometric luminosity), the opposite of what is predicted by standard
accretion torque theory. No changes in the shape of the 20-100 keV pulsed
energy spectrum were detected, so that a very drastic change in the spectrum
below 20 keV or the pulsed fraction would be required to make the 20-60 keV
pulsed flux a poor luminosity tracer. These are the first observations which
flatly contradict standard magnetic disk accretion theory, and they may have
important implications for understanding the spin evolution of X-ray binaries,
cataclysmic variables, and protostars. We briefly discuss the possibility that
GX 1+4 may be accreting from a retrograde disk during spin-down, as previously
suggested.Comment: 10 pages including 3 PS figures. To appear in ApJ Letter
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