3,567 research outputs found

    Temporal frequency of radio emissions for the April 25, 1984 flare

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    The National Geophysical Data Center archives data of the solar-terrestrial environment. The USAF Radio Solar Telescope Network (RSTN) data allow performance of time series analysis to determine temporal oscillations as low as three seconds. The X13/3B flare which erupted in region 4474 (S12E43) on the 24 to 25 of April 1984, was selected. The soft X-rays, 1 to 8 A, remained above X-levels for 50 minutes and the radio emissions measured at Learmonth Solar Observatory reached a maximum of 3.15 x 10 to the 5th power SFUs at 410 MHz at 0000UT. A power spectral analysis of the fixed frequency RSTN data from Learmonth shows possible quasi-periodic fluctuations in the range two to ten seconds. Repetition rates or quasi-periodicities, in the case of the power spectral analysis, generally showed the same trends as the average solar radio flux at 245 and 8800 MHz. The quasi-periodicities at 1415 MHz showed no such trends

    Air Pollution and Lost Work

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    A Poisson specification of the relationship between atmospheric pollution and lost work days is estimated.An important feature of the procedure is control for city-specific effects. A major source of ambiguity in interpreting the results of observational data on pollution versus health status or death rates is that pollution in a city may be correlated with other characteristics ofthat city that affect these outcomes but are not controlled for in the analysis. Or, individual attributes of residents may be correlated with pollution levels but notaccounted for in the analysis. Our results suggest a statistically significantand quantitatively important effect of total suspended particulates on work days lost. A standard deviation increase in total suspended particulates is associated with approximately a ten percent increase in work days lost. As a concomitant of our analysis, we also find a substantial relationship between smoking by others in the individual's household and work days lost by non-smokers.

    Active flutter control for flexible vehicles, volume 1

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    An active flutter control methodology based on linear quadratic gaussian theory and its application to the control of a super critical wing is presented. Results of control surface and sensor position optimization are discussed. Both frequency response matching and residualization used to obtain practical flutter controllers are examined. The development of algorithms and computer programs for flutter modeling and active control design procedures is reported

    Preference purification and the inner rational agent:A critique of the conventional wisdom of behavioural welfare economics

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    Neoclassical economics assumes that individuals have stable and context-independent preferences, and uses preference-satisfaction as a normative criterion. By calling this assumption into question, behavioural findings cause fundamental problems for normative economics. A common response to these problems is to treat deviations from conventional rational-choice theory as mistakes, and to try to reconstruct the preferences that individuals would have acted on, had they reasoned correctly. We argue that this preference purification approach implicitly uses a dualistic model of the human being, in which an inner rational agent is trapped in an outer psychological shell. This model is psychologically and philosophically problematic

    Entry in the ADHD drugs market: Welfare impact of generics and me-toos

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    Recent decades have seen a growth in treatments for attention deficit hyperactivity disorder (ADHD) including many branded and generic drugs. In the early 2000's, new drug entry dramatically altered market shares. We estimate a demand system for ADHD drugs and assess the welfare impact of new drugs. We find that entry induced large welfare gains by reducing prices of substitute drugs, and by providing alternative delivery mechanisms for existing molecules. Our results suggest that the success of follow-on patented drugs may come from unanticipated innovations like delivery mechanisms, a factor ignored by proposals to retard new follow-on drug approvals

    Energy Dissipation in Interstellar Cloud Collisions

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    We present a study of the kinetic energy dissipation in interstellar cloud collisions. The main aim is to understand the dependence of the elasticity (defined as the ratio of the final to the initial kinetic energy of the clouds) on the velocity and mass ratio of the colliding clouds, magnetic field strength, and gas metallicity for head-on collisions. The problem has been studied both analytically and via numerical simulations. We have derived handy analytical relationships that well approximate the analogous numerical results. The main findings of this work are: (i) the kinetic energy dissipation in cloud collisions is minimum (i.e. the collision elasticity is maximum) for a cloud relative velocity vr30kms1v_r \simeq 30 km s^{-1}; (ii) the above minimum value is proportional ZLc2Z L_c^2, where ZZ is the metallicity and LcL_c is the cloud size: the larger is ZLc2Z L_c^2 the more dissipative (i.e. inelastic) the collision will be; (iii) in general, we find that the energy dissipation decreases when the magnetic field strength, and mass ratio of the clouds are increased and the metallicity is decreased, respectively. We briefly discuss the relevance of this study to the global structure of the interstellar medium and to galaxy formation and evolution.Comment: 16 pages, aasms LaTeX, 7 figures. ApJ, accepte

    Why the Realist-Instrumentalist Debate about Rational Choice Rests on a Mistake

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    Within the social sciences, much controversy exists about which status should be ascribed to the rationality assumption that forms the core of rational choice theories. Whilst realists argue that the rationality assumption is an empirical claim which describes real processes that cause individual action, instrumentalists maintain that it amounts to nothing more than an analytically set axiom or ‘as if’ hypothesis which helps in the generation of accurate predictions. In this paper, I argue that this realist-instrumentalist debate about rational choice theory can be overcome once it is realised that the rationality assumption is neither an empirical description nor an ‘as if’ hypothesis, but a normative claim

    License prices for financially constrained firms

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    It is often alleged that high auction prices inhibit service deployment. We investigate this claim under the extreme case of financially constrained bidders. If demand is just slightly elastic, auctions maximize consumer surplus if consumer surplus is a convex function of quantity (a common assumption), or if consumer surplus is concave and the proportion of expenditure spent on deployment is greater than one over the elasticity of demand. The latter condition appears to be true for most of the large telecom auctions in the US and Europe. Thus, even if high auction prices inhibit service deployment, auctions appear to be optimal from the consumers’ point of view

    Assessment of Connections Between Knowledge- Based Economy Characteristics and Selected Macroeconomic Categories in the European Union's Countries by Means of Panel Models

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    The aim of the article is to analyze the impact of knowledge-based economy variables on the selected macroeconomic categories - the share of total investments in GDP and the employment rate- in European Union's countries in the years 2000-2007, conducted with application of panel models.Celem artykułu jest analiza wpływu zmiennych opisujących gospodarkę opartą na wiedzy na podstawowe kategorie makroekonomiczne - udział całkowitych inwestycji w PKB i stopę zatrudnienia - w krajach Unii Europejskiej (z podziałem na kraje UE-15 i nowe kraje członkowskie UE) w latach 2000-2007, przeprowadzona w oparciu o modele panelowe

    Common Causes and The Direction of Causation

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    Is the common cause principle merely one of a set of useful heuristics for discovering causal relations, or is it rather a piece of heavy duty metaphysics, capable of grounding the direction of causation itself? Since the principle was introduced in Reichenbach’s groundbreaking work The Direction of Time (1956), there have been a series of attempts to pursue the latter program—to take the probabilistic relationships constitutive of the principle of the common cause and use them to ground the direction of causation. These attempts have not all explicitly appealed to the principle as originally formulated; it has also appeared in the guise of independence conditions, counterfactual overdetermination, and, in the causal modelling literature, as the causal markov condition. In this paper, I identify a set of difficulties for grounding the asymmetry of causation on the principle and its descendents. The first difficulty, concerning what I call the vertical placement of causation, consists of a tension between considerations that drive towards the macroscopic scale, and considerations that drive towards the microscopic scale—the worry is that these considerations cannot both be comfortably accommodated. The second difficulty consists of a novel potential counterexample to the principle based on the familiar Einstein Podolsky Rosen (EPR) cases in quantum mechanics
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