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ΠΠ½ΡΠΎΡΠΌΠ°ΡΠΈΠΎΠ½Π½Π°Ρ ΡΠΈΡΡΠ΅ΠΌΠ° ΡΠΏΡΠ°Π²Π»Π΅Π½ΠΈΡ ΡΠΊΠΎΠ»ΠΎΠ³ΠΎ-Π³Π΅ΠΎΠ±ΠΎΡΠ°Π½ΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΠΈ ΠΏΡΠΎΡΡΡΠ°Π½ΡΡΠ²Π΅Π½Π½ΡΠΌΠΈ Π΄Π°Π½Π½ΡΠΌΠΈ Ρ ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π½ΠΈΠ΅ΠΌ ΠΠΠ‘ Google Maps ΠΈ Google Earth
Parallel Quantum-Point-Contacts as High-Frequency-Mixers
We present the results of high-frequency mixing experiments performed upon
parallel quantum point-contacts defined in the two-dimensional electron gas of
an Al_{x}Ga_{1-x}As/GaAs-heterostructure. The parallel geometry, fabricated
using a novel double-resist technology, enables the point-contact device to be
impedance matched over a wide frequency range and, in addition, increases the
power levels of the mixing signal while simultaneously reducing the parasitic
source-drain capacitance. Here, we consider two parallel quantum point-contact
devices with 155 and 110 point-contacts respectively; both devices operated
successfully at liquid helium and liquid nitrogen temperatures with a minimal
conversion loss of 13 dB.Comment: 4 figures, RevTeX, to be published in the 16 June 1997 issue of
Applied Physic Letter
ΠΠ²ΡΠΎΠΌΠ°ΡΠΈΠ·Π°ΡΠΈΡ ΠΏΡΠΎΡΠ΅ΡΡΠ° ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°ΡΠ΅Π»ΡΠ½ΡΡ ΡΡΠ°Π΅ΠΊΡΠΎΡΠΈΠΉ
ΠΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ Π½Π°ΠΊΠΎΠΏΠ»Π΅Π½ΠΈΡ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π° Π² ΡΠΏΠ»Π°Π²Π΅ Π½ΠΈΠΊΠ΅Π»ΠΈΠ΄Π° ΡΠΈΡΠ°Π½Π° ΠΏΡΠΈ ΡΠ»Π΅ΠΊΡΡΠΎΠ»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠΌ Π½Π°Π²ΠΎΠ΄ΠΎΡΠΎΠΆΠΈΠ²Π°Π½ΠΈΠΈ
Π ΠΏΡΠΎΡΠ΅ΡΡΠ΅ ΡΠ°Π±ΠΎΡΡ ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΠΎΡΡ Π½Π°ΡΡΡΠ΅Π½ΠΈΠ΅ ΠΎΠ±ΡΠ°Π·ΡΠΎΠ² ΠΈΠ· ΡΠΏΠ»Π°Π²Π° Π½ΠΈΠΊΠ΅Π»ΠΈΠ΄Π° ΡΠΈΡΠ°Π½Π° ΡΠ»Π΅ΠΊΡΡΠΎΠ»ΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠΌ ΡΠΏΠΎΡΠΎΠ±ΠΎΠΌ ΠΏΡΠΈ ΡΠ°Π·Π½ΡΡ
ΡΠ΅ΠΌΠΏΠ΅ΡΠ°ΡΡΡΠ°Ρ
ΠΈ ΠΏΠ»ΠΎΡΠ½ΠΎΡΡΡΡ
ΡΠΎΠΊΠ° Ρ ΡΠ΅Π»ΡΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠ΅ ΡΠ°ΠΊΡΠΎΡΠΎΠ², ΠΊΠΎΡΠΎΡΡΠ΅ Π²Π»ΠΈΡΡΡ Π½Π° Π΅Π³ΠΎ ΠΏΠΎΠ³Π»ΠΎΡΠ΅Π½ΠΈΠ΅ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π°.
Π ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠ΅ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΠΉ Π±ΡΠ»ΠΎ ΠΎΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΎ, ΠΊΠ°ΠΊ ΡΡΠΈ ΡΠ°ΠΊΡΠΎΡΡ Π²Π»ΠΈΡΡΡ Π½Π° Π½Π°Π²ΠΎΠ΄ΠΎΡΠΎΠΆΠΈΠ²Π°Π½ΠΈΠ΅.The effects of solution temperature, current density, grain size and charging time on the hydrogen absorption of NiβTi superelastic alloy immersed in 0.9% NaCl solution have been investigated systematically by hydrogen analyzer RHEN602. For hydrogen cathodic charging under constant current density, upon increasing solution temperature and charging time, the hydrogen concentration increased. As current density increases, the hydrogen concentration initially increases rapidly, then slightly changes. The grain size of materials also has an influence on the hydrogen absorption
Coherent coupling of two quantum dots embedded in an Aharonov-Bohm ring
We define two laterally gated small quantum dots (~ 15 electrons) in an
Aharonov-Bohm geometry in which the coupling between the two dots can be
broadly changed. For weakly coupled quantum dots we find Aharonov-Bohm
oscillations. In an intermediate coupling regime we concentrate on the
molecular states of the double dot and extract the magnetic field dependence of
the coherent coupling.Comment: 6 pages, 4 figure
Investigation of DFIG with Fault RideThrough Capability
Abstract--In this paper, the ability of doubly fed induction generators to provide voltage stability support in weak transmission networks is investigated. Specifically, the response of wind turbines to voltage dips at the point of common coupling and its effects on system stability are analyzed. A control strategy for the operation of the grid and rotor side converters is developed in order to support the grid voltage by injecting reactive power during and after grid fault events. The performance of the strategy is analyzed for different voltage dips at the point of common coupling of a wind farm and compared with the case when the converters do not provide any voltage support. Simulations are performed using a simplified model of the Chilean transmission network. This system is considered to be a good example of weak power system, because of its radial configuration
Discovery and Kinetic Profiling of 7-Aryl-1,2,4-triazolo[4,3-a]pyridines: Positive Allosteric Modulators of the Metabotropic Glutamate Receptor 2
We report the synthesis and biological evaluation of a series of 7-aryl-1,2,4-triazolo[4,3-c]pyridines with mGlu(2) positive allosteric modulator (PAM) activity and affinity. Besides traditional in vitro parameters of potency and affinity, kinetic parameters k(on), k(off) and residence time (RT) were determined. The PAMs showed various kinetic profiles; k(on) values ranged over 2 orders of magnitude, whereas RT values were within a 10-fold range. Association rate constant k(on) was linearly correlated to affinity. Evaluation of a short, medium, and long RT compound in a label-free assay indicated a correlation between RT and functional effect. The effects of long RT compound 9 on sleep-wake states indicated long RT was translated into sustained inhibition of rapid eye movement (REM) in vivo. These results show that affinity-only driven selection would have resulted in mGlu(2) PAMs with high values for k(on) but not necessarily optimized RT, which is key to predicting optimal efficacy in vivo
Predictive Value of Pharmacokinetics-Adjusted Phenotypic Susceptibility on Response to Ritonavir-Enhanced Protease Inhibitors (PIs) in Human Immunodeficiency Virus-Infected Subjects Failing Prior PI Therapy
The activities of protease inhibitors in vivo may depend on plasma concentrations and viral susceptibility. This nonrandomized, open-label study evaluated the relationship of the inhibitory quotient (IQ [the ratio of drug exposure to viral phenotypic susceptibility]) to the human immunodeficiency virus type 1 (HIV-1) viral load (VL) change for ritonavir-enhanced protease inhibitors (PIs). Subjects on PI-based regimens replaced their PIs with ritonavir-enhanced indinavir (IDV/r) 800/200 mg, fosamprenavir (FPV/r) 700/100 mg, or lopinavir (LPV/r) 400/200 mg twice daily. Pharmacokinetics were assessed at day 14; follow-up lasted 24 weeks. Associations between IQ and VL changes were examined. Fifty-three subjects enrolled, 12 on IDV/r, 33 on FPV/r, and 8 on LPV/r. Median changes (n-fold) (FC) of 50% inhibitory concentrations (IC50s) to the study PI were high. Median 2-week VL changes were β0.7, β0.1, and β1.0 log10 for IDV/r, FPV/r, and LPV/r. With FPV/r, correlations between the IQ and the 2-week change in VL were significant (Spearman's r range, β0.39 to β0.50; P β€ 0.029). The strongest correlation with response to FPV/r was the IC50 FC (r = 0.57; P = 0.001), which improved when only adherent subjects were included (r = 0.68; P = 0.001). In multivariable analyses of the FPV/r arm that included FC, one measure of the drug concentration, corresponding IQ, baseline VL, and CD4, the FC to FPV was the only significant predictor of VL decline (P < 0.001). In exploratory analyses of all arms, the area under the concentration-time curve IQ was correlated with the week 2 VL change (r = β0.72; P < 0.001). In conclusion, in PI-experienced subjects with highly resistant HIV-1, short-term VL responses to RTV-enhanced FPV/r correlated best with baseline susceptibility. The IQ improved correlation in analyses of all arms where a greater range of virologic responses was observed
Phospholipids and sports performance
Phospholipids are essential components of all biological membranes. Phosphatidylcholine (PC) and Phosphatidylserine (PS) are Phosphatidyl-phospholipids that are required for normal cellular structure and function. The participation in physical activity often challenges a variety of physiological systems; consequently, the ability to maintain normal cellular function during activity can determine sporting performance. The participation in prolonged intense exercise has been shown to reduce circulatory choline concentrations in some individuals. As choline is a pre-cursor to the neurotransmitter Acetylcholine, this finding has encouraged researchers to investigate the hypothesis that supplementation with PC (or choline salts) could enhance sporting performance. Although the available data that evaluates the effects of PC supplementation on performance are equivocal, acute oral supplementation with PC (~0.2 g PC per kg body mass) has been demonstrated to improve performance in a variety of sporting activities where exercise has depleted circulatory choline concentrations. Short term oral supplementation with soy-derived PS (S-PS) has been reported to attenuate circulating cortisol concentrations, improve perceived well-being, and reduce perceived muscle soreness after exercise. More recently, short term oral supplementation (750 mg per day of S-PS for 10 days) has been demonstrated to improve exercise capacity during high intensity cycling and tended to increase performance during intermittent running. Although more research is warranted to determine minimum dietary Phospholipid requirements for optimal sporting performance, these findings suggest that some participants might benefit from dietary interventions that increase the intakes of PC and PS
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