2,007 research outputs found
On Quantity Competition and Transmission Constraints in Electricity Market
In this paper we characterize equilibria in a quantity game where symmetric firms face a local demand together with an export-constrained demand. Firms have unlimited access to a local demand but a restricted access to a second market, like in the electricity network where generators compete to satisfy demand but competition is restricted by transmission capacity. We show the existence of an effective demand that is continuous but not differentiable due to the transmission constraint. Three types of equilibria emerge in this context, parametrized by capacity. First, a symmetric equilibrium (unique) when the access to the second market is constrained. Second, a set of continuous and asymmetric equilibria with a fully used link but not constrained; and finally, a symmetric and unique equilibrium in which the link is not fully used. We also show how multiplicity of equilibria tends to disappear as the number of competitors increaseelectricity markets, Cournot games, capacity constraints
Can the Gains from Argentina's Utilities Reform Offset Credit Shocks?
Computable general equilibrium, Regulation
Are cost models useful for telecoms regulators in developing countries?
Worldwide privatization of the telecommunications industry, and the introduction of competition in the sector, together with the ever-increasing rate of technological advance in telecommunications, raise new and critical challenges for regulation. Fo matters of pricing, universal service obligations, and the like, one question to be answered is this: What is the efficient cost of providing the service to a certain area or type of customer? As developing countries build up their capacity to regulate their privatized infrastructure monopolies, cost models are likely to prove increasingly important in answering this question. Cost models deliver a number of benefits to a regulator willing to apply them, but they also ask for something in advance: information. Without information, the question cannot be answered. The authors introduce cost models and establish their applicability when different degrees of information are available to the regulator. They do no by running a cost model with different sets of actual data form Argentina's second largest city, and comparing results. Reliable, detailed information is generally scarce in developing countries. The authors establish the minimum information requirements for a regulator implementing a cost proxy model approach, showing that this data constraint need not be that binding.ICT Policy and Strategies,Decentralization,Environmental Economics&Policies,Economic Theory&Research,Business Environment,ICT Policy and Strategies,Environmental Economics&Policies,Geographical Information Systems,Economic Theory&Research,Educational Technology and Distance Education
Conformations of N-Heterocyclic Carbene Ligands in Ruthenium Complexes Relevant to Olefin Metathesis
The structure of ruthenium-based olefin metathesis catalyst 3 and model π-complex 5 in solution and in the solid state are reported. The N-tolyl ligands, due to their lower symmetry than the traditional N-mesityl substituents, complicate this analysis, but ultimately provide explanation for the enhanced reactivity of 3 relative to standard catalyst 2. The tilt of the N-tolyl ring provides additional space near the ruthenium center, which is consistent with the enhanced reactivity of 3 toward sterically demanding substrates. Due to this tilt, the more sterically accessible face bears the two methyl substituents of the N-aryl rings. These experimental studies are supported by computational studies of these complexes by DFT. The experimental data provides a means to validate the accuracy of the B3LYP and M06 functionals. B3LYP provides geometries that match X-ray crystal structural data more closely, though it leads to slightly less (0.5 kcal mol^(−1)) accuracy than M06 most likely because it underestimates attractive noncovalent interactions
Functional reduction of SK3-mediated currents precedes AMPA-receptor-mediated excitotoxicity in dopaminergic neurons
In primary cultures of mesencephalon small-conductance calcium-activated potassium channels (SK) are expressed in dopaminergic neurons. We characterized SK-mediated currents (ISK) in this system and evaluated their role on homeostasis against excitotoxicity. ISK amplitude was reduced by the glutamatergic agonist AMPA through a reduction in SK channel number in the membrane. Blockade of ISK for 12 h with apamin or NS8593 reduced the number of dopaminergic neurons in a concentration-dependent manner. The effect of apamin was not additive to AMPA toxicity. On the other hand, two ISK agonists,1-EBIO and CyPPA, caused a significant reduction of spontaneous loss of dopaminergic neurons. 1-EBIO reversed the effects of both AMPA and apamin as well. Thus, ISK influences survival and differentiation of dopaminergic neurons in vitro, and is part of protective homeostatic responses, participating in a rapidly acting negative feedback loop coupling calcium levels, neuron excitability and cellular defenses. Fil: Benitez, Bruno A.. Harvard Medical School; Estados UnidosFil: Belálcazar, Helen M.. Harvard Medical School; Estados UnidosFil: Anastasia Gonzalez, Agustin. Washington University in St. Louis; Estados Unidos. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Mamah, Daniel. Washington University in St. Louis; Estados UnidosFil: Zorumski, Charles. Washington University in St. Louis; Estados UnidosFil: Masco, Daniel Hugo. Washington University in St. Louis; Estados Unidos. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Centro de Biología Celular y Molecular; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones Biológicas y Tecnológicas. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas, Físicas y Naturales. Instituto de Investigaciones Biológicas y Tecnológicas; ArgentinaFil: Herrera, Daniel. Harvard Medical School; Estados UnidosFil: de Erausquin, Gabriel Alejandro. Harvard Medical School; Estados Unido
Improvements in attention and cardiac autonomic modulation after a 2-weeks sprint interval training program: a fidelity approach
This study aimed to: (1) investigate the influence of a 2-weeks sprint interval training (SIT) program on aerobic capacity, cardiac autonomic control, and components of attention in young healthy university students; and (2) to ascertain whether training fidelity would influence these adaptations. One hundred and nine participants were divided into an experimental (EG) and control (CG) groups. The EG performed a SIT program that consisted of 6 sessions of 4 x 30 s "all-out" efforts on a cycle ergometer, interspersed with active rests of 4 min. The criterion for fidelity was achieving >90% of estimated maximum heart rate (HR) during sprint bouts. After analyses, the EG was divided into HIGH (n = 26) and LOW(n = 46) fidelity groups. Components of attention were assessed using the Attention Network Test (ANT). Aerobic capacity (VO(2)max) was estimated while the sum of skinfolds was determined. Autonomic control of HR was assessed by means of HR variability (HRV) and HR complexity at rest and during ANT. Both HIGH and LOW significantly increased aerobic capacity, vagal modulation before and during ANT, and executive control, and decreased body fatness after SIT (p < 0.05). However, only participants from HIGH showed an increase in HR complexity and accuracy in ANT when compared to LOW (p < 0.05). Two weeks of SIT improved executive control, body fatness, aerobic fitness, and autonomic control in university students with better results reported in those individuals who exhibited high fidelity
First results on light readout from the 1-ton ArDM liquid argon detector for dark matter searches
ArDM-1t is the prototype for a next generation WIMP detector measuring both
the scintillation light and the ionization charge from nuclear recoils in a
1-ton liquid argon target. The goal is to reach a minimum recoil energy of
30\,keVr to detect recoiling nuclei. In this paper we describe the experimental
concept and present results on the light detection system, tested for the first
time in ArDM on the surface at CERN. With a preliminary and incomplete set of
PMTs, the light yield at zero electric field is found to be between 0.3-0.5
phe/keVee depending on the position within the detector volume, confirming our
expectations based on smaller detector setups.Comment: 14 pages, 10 figures, v2 accepted for publication in JINS
Data Deluge in Astrophysics: Photometric Redshifts as a Template Use Case
Astronomy has entered the big data era and Machine Learning based methods
have found widespread use in a large variety of astronomical applications. This
is demonstrated by the recent huge increase in the number of publications
making use of this new approach. The usage of machine learning methods, however
is still far from trivial and many problems still need to be solved. Using the
evaluation of photometric redshifts as a case study, we outline the main
problems and some ongoing efforts to solve them.Comment: 13 pages, 3 figures, Springer's Communications in Computer and
Information Science (CCIS), Vol. 82
Discovery of Two Distant Type Ia Supernovae in the Hubble Deep Field North with the Advanced Camera for Surveys
We present observations of the first two supernovae discovered with the
recently installed Advanced Camera for Surveys (ACS) on the Hubble Space
Telescope. The supernovae were found in Wide Field Camera images of the Hubble
Deep Field North taken with the F775W, F850LP, and G800L optical elements as
part of the ACS guaranteed time observation program. Spectra extracted from the
ACS G800L grism exposures confirm that the objects are Type Ia supernovae (SNe
Ia) at redshifts z=0.47 and z=0.95. Follow-up HST observations have been
conducted with ACS in F775W and F850LP and with NICMOS in the near-infrared
F110W bandpass, yielding a total of 9 flux measurements in the 3 bandpasses
over a period of 50 days in the observed frame. We discuss many of the
important issues in doing accurate photometry with the ACS. We analyze the
multi-band light curves using two different fitting methods to calibrate the
supernovae luminosities and place them on the SNe Ia Hubble diagram. The
resulting distances are consistent with the redshift-distance relation of the
accelerating universe model, although evolving intergalactic grey dust remains
as a less likely possibility. The relative ease with which these SNe Ia were
found, confirmed, and monitored demonstrates the potential ACS holds for
revolutionizing the field of high-redshift SNe Ia, and therefore of testing the
accelerating universe cosmology and constraining the "epoch of deceleration".Comment: 11 pages, 8 embedded figures. Accepted for publication in Ap
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