7,599 research outputs found
The Determinants of Music Piracy in a Sample of College Students
Why do some individuals pirate digital music while others pay for it? Using data on a sample of undergraduate students, we study the determinants of music piracy by looking at whether a respondent’s last song was obtained illegally or not. In doing so, we incorporate (i) the individual-specific transactions costs that constitute the effective price of illegal music; and (ii) individual willingness to pay (WTP) for digital music, which we elicit using a simple field experiment and which we use to control for the unobserved heterogeneity of preferences between respondents. Our empirical results indicate that a respondent’s subjective probability of facing a lawsuit and her degree of morality both have a negative impact on the likelihood that her last song was obtained illegally. These results are robust whether WTP is estimated parametrically or nonparametrically. We conclude by discussing the practical implications of our findings.Music Piracy, Transactions Costs, Subjective Expectations
The Impact of Acid Deposition on Groundwater: A Review
Theoretical mechanisms and empirical evidence of the potential acidification of groundwater under forested soils in Europe have been reviewed in order to provide a starting point for an assessment of the acidification of groundwater in the scope of the Acid Rain study carried out at IIASA. Basic characteristics of forested soil-water systems are presented as a background to a discussion of the transport and the release and retention of elements. The report relates the impact of acid deposition of groundwater to the pedology, the climatic regime and the geohydrology of the region. Some approaches of modeling the problem are reviewed, including dynamic models and sensitivity analysis. A procedure for assessing the impact of various energy pathways on the potential for acidification of groundwater is outlined. The method proposed combines a regional ranking of the static sensitivity with a dynamic simulation of the impact of acid deposition on the chemistry of top soil
The Properties of Satellite Galaxies in External Systems. I. Morphology and Structural Parameters
We present the first results of an ongoing project to study the
morphological, kinematical, dynamical, and chemical properties of satellite
galaxies of external giant spiral galaxies. The sample of objects has been
selected from the catalogue by Zaritsky et al. (1997). The paper analyzes the
morphology and structural parameters of a subsample of 60 such objects. The
satellites span a great variety of morphologies and surface brightness
profiles. About two thirds of the sample are spirals and irregulars, the
remaining third being early-types. Some cases showing interaction between pairs
of satellites are presented and briefly discussed.Comment: Accepted for publication in Astrophys. Journal Supp. Se
Viking '75 spacecraft design and test summary. Volume 1: Lander design
The Viking Mars program is summarized. The design of the Viking lander spacecraft is described
Viking '75 spacecraft design and test summary. Volume 3: Engineering test summary
The engineering test program for the lander and the orbiter are presented. The engineering program was developed to achieve confidence that the design was adequate to survive the expected mission environments and to accomplish the mission objective
Completeness of case ascertainment and survival time error in English cancer registries: impact on 1-year survival estimates.
BACKGROUND: It has been suggested that cancer registries in England are too dependent on processing of information from death certificates, and consequently that cancer survival statistics reported for England are systematically biased and too low. METHODS: We have linked routine cancer registration records for colorectal, lung, and breast cancer patients with information from the Hospital Episode Statistics (HES) database for the period 2001-2007. Based on record linkage with the HES database, records missing in the cancer register were identified, and dates of diagnosis were revised. The effects of those revisions on the estimated survival time and proportion of patients surviving for 1 year or more were studied. Cases that were absent in the cancer register and present in the HES data with a relevant diagnosis code and a relevant surgery code were used to estimate (a) the completeness of the cancer register. Differences in survival times calculated from the two data sources were used to estimate (b) the possible extent of error in the recorded survival time in the cancer register. Finally, we combined (a) and (b) to estimate (c) the resulting differences in 1-year cumulative survival estimates. RESULTS: Completeness of case ascertainment in English cancer registries is high, around 98-99%. Using HES data added 1.9%, 0.4% and 2.0% to the number of colorectal, lung, and breast cancer registrations, respectively. Around 5-6% of rapidly fatal cancer registrations had survival time extended by more than a month, and almost 3% of rapidly fatal breast cancer records were extended by more than a year. The resulting impact on estimates of 1-year survival was small, amounting to 1.0, 0.8, and 0.4 percentage points for colorectal, lung, and breast cancer, respectively. INTERPRETATION: English cancer registration data cannot be dismissed as unfit for the purpose of cancer survival analysis. However, investigators should retain a critical attitude to data quality and sources of error in international cancer survival studies
Seeing Galaxies Through Thick & Thin. III. HST Imaging of the Dust in Backlit Spiral Galaxies
We present analysis of WFPC2 imaging of two spiral galaxies partially backlit
by E/S0 systems in the pairs AM1316-241 and AM0500-620, and the spiral
foreground system in NGC 1275. Images in B and I are used to determine the
reddening curve of in these systems. The spiral component of AM1316-241 shows
dust strongly concentrated in discrete arms, with a reddening law very close to
the Milky Way mean. The dust distribution is scale-free between about 100 pc
and the arm scale. The spiral in AM0500-620 shows dust concentrated in arms and
interarm spurs, with measurable interarm extinction as well. Although its dust
properties are less well-determined, we find evidence for a steeper extinction
law here. The shape of the reddening law suggests that, at least in AM1316-241,
we have resolved most of the dust structure. In AM0500-620, the slope of the
fractal perimeter-scale relation steepens systematically from low to high
extinction. In AM1316-241, we cannot determine a unique fractal dimension from
the defining area-perimeter relation, so the projected dust distribution is
best defined as fractal-like. In neither galaxy do we see regions even on
single-pixel scales in spiral arms with AB > 2.5. The measurements in NGC 1275
are compromised by our lack of independent knowledge of the foreground system's
light distribution, but masked sampling of the absorption suggests an effective
reddening curve much flatter than the Milky Way mean (perhaps indicating that
the foreground system has been affected by immersion in the hot intracluster
gas).Comment: Astronomical Journal, in press. 13 figures. Full-size PostScript
figures available at http://www.astr.ua.edu/preprints/kee
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Increase-Decrease Game under Imperfect Competition in Two-stage Zonal Power Markets Part II: Solution Algorithm
In part I of this paper, we proposed a Mixed-Integer Linear Program (MILP) to analyse imperfect competition of oligopoly producers in two-stage zonal power markets. In part II of this paper, we propose a solution algorithm which decomposes the proposed MILP model into several subproblems and solve them in parallel and iteratively. Our solution algorithm reduces the solution time of the MILP model and it allows us to analyze largescale examples. To tackle the multiple Subgame Perfect Nash Equilibria (SPNE) situation, we propose a SPNE-band approach. The SPNE band is split into several subintervals and the proposed solution algorithm finds a representative SPNE in each subinterval. Each subinterval is independent from each other, so this structure enables us to use parallel computing. We also design a pre-feasibility test to identify the subintervals without SPNE. Our proposed solution algorithm and our SPNE-band approach are demonstrated on the 6-node and the modified IEEE 30-node example systems. The computational tractability of our solution algorithm is illustrated for the IEEE 118-node and 300-node systems
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Increase-Decrease Game under Imperfect Competition in Two-stage Zonal Power Markets Part I: Concept Analysis
This paper is part I of a two-part paper. It proposes a two-stage game to analyze imperfect competition of producers in zonal power markets with a day-ahead and a real-time market. We consider strategic producers in both markets. They need to take both markets into account when deciding what to bid in each market. The demand shocks between these markets are modeled by several scenarios. The two-stage game is formulated as a Twostage Stochastic Equilibrium Problem with Equilibrium Constraints (TS-EPEC). Then it is further reformulated as a two-stage stochastic Mixed-Integer Linear Program (MILP). The solution of this MILP gives the Subgame Perfect Nash Equilibrium (SPNE). To tackle multiple SPNE, we design a procedure which _nds all SPNE with di_erent total dispatch costs. The proposed MILP model is solved using Benders decomposition embedded in the CPLEX solver. The proposed MILP model is demonstrated on the 6-node and the IEEE 30-node example systems
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Simulation and Evaluation of Zonal Electricity Market Designs
Zonal pricing with countertrading (a market-based redispatch) gives arbitrage opportunities to the power producers located in the export-constrained nodes. They can increase their profit by increasing the output in the day-ahead market and decrease it in the real-time market (the inc-dec game). We show that this leads to large inefficiencies in a standard zonal market. We also show how the inefficiencies can be significantly mitigated by changing the design of the real-time market. We consider a two-stage game with oligopoly producers, wind-power shocks and real-time shocks. The game is formulated as a two-stage stochastic equilibrium problem with equilibrium constraints (EPEC), which we recast into a two-stage stochastic Mixed-Integer Bilinear Program (MIBLP). We present numerical results for a six-node and the IEEE 24-node system
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