3,003 research outputs found
Commitment as investment under uncertainty
Irreversible investment and the techniques associated with pricing real options have led to significant advances many areas. We broaden this range of applications, showing how the techniques can apply to many policy problems in finance, macroeconomics, and trade policy. With small changes, standard techniques can handle a broad range of strategic problems related to policy. The decision to commit is like the decision to make an irreversible investment. Explicitly considering and correctly valuing the option to wait makes discretion relatively more attractive, implies that increased uncertainty increases the gain to discretion, and results in policy which displays hysteresis.Investments
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
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
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
Economic modeling of the combined effects of HIV-disease, cholesterol and lipoatrophy based on ACTG 5142 trial data
<p>Abstract</p> <p>Background</p> <p>This study examines the cost and consequences of initiating an ARV regimen including Lopinavir/ritonavir (LPV/r) or Efavirenz (EFV), using data from a recent clinical trial in a previously published model of HIV-disease.</p> <p>Methods</p> <p>We populated the Markov model of HIV-disease with data from ACTG 5142 study to estimate the economic outcomes of starting ARV therapy with a PI-containing regimen as compared to an NNRTI-containing regimen, given their virologic and immunologic efficacy and effects on cholesterol and lipoatrophy. CNS toxicities and GI tolerability were not included in the model because of their transient nature or low cost remedies, and therefore lack of economic impact. CD4+ T-cell counts and the HIV-1 RNA (viral load) values from the study were used to assign a specific health state (HS) to each patient for each quarter year. The resulting frequencies used as "raw" data directly into the model obviate the reliance on statistical tests, and allow the model to reflect actual patient behavior in the clinical trial. An HS just below the last observed HS was used to replace a missing value.</p> <p>Results</p> <p>The modeled estimates (undiscounted) for the LPV/r-based regimen resulted in 1.41 quality-adjusted life months (QALMs) gained over a lifetime compared to the EFV-based regimen. The LPV/r-based regimen incurred 88,829/QALY. Most of the higher costs accrue before the 7th year of treatment and were offset by subsequent savings. The estimates are highly sensitive to the effect of lipoatrophy on Health-related Quality of Life (HRQOL), but not to the effect of cholesterol levels.</p> <p>Conclusions</p> <p>The cost effectiveness of ARV regimens may be strongly affected by enduring AEs, such as lipoatrophy. It is important to consider specific AE effects from all drugs in a regimen when ARVs are compared.</p> <p>Trial registration</p> <p>(ClinicalTrials.gov number, <a href="http://www.clinicaltrials.gov/ct2/show/NCT00050895">NCT00050895</a><url>http://[ClinicalTrials.gov]</url>).</p
ΠΠΏΡΠ΅Π΄Π΅Π»Π΅Π½ΠΈΠ΅ ΠΏΠΎΠ³ΡΠ΅ΡΠ½ΠΎΡΡΠΈ ΠΌΠ°ΡΠ΅ΠΌΠ°ΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΠΌΠΎΠ΄Π΅Π»ΠΈ ΠΏΡΠΎΠ³ΡΠ°ΠΌΠΌΡ ΠΊΠ°Π»ΠΈΠ±ΡΠΎΠ²ΠΊΠΈ ΠΏΠΎ ΡΡΡΠ΅ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ LabSOCS
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
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