3,945 research outputs found

    Inefficiency

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    We introduce an ordinal model of efficiency measurement. Our primitive is a notion of efficiency that is comparative, but not cardinal or absolute. In this framework, we postulate axioms that we believe an ordinal efficiency measure should satisfy. Primary among these are choice consistency and planning consistency, which guide the measurement of efficiency in a firm with access to multiple technologies. Other axioms include symmetry, which states that the names of commodities do not matter, scale-invariance, which says that units of measurement of commodities does not matter, and strong monotonicity, which states that efficiency should decrease if the inputs and outputs remain static when the technology becomes unambiguously more efficient. These axioms characterize a unique ordinal efficiency measure which is represented by the coefficient of resource utilization. By replacing symmetry (the weakest of our axioms) with a very mild continuity condition, we obtain a family of path-based measures.Efficiency Measurement, Coefficient of Resource Utilization, Ordinal, Choice Consistency, Planning Consistency, Path-based

    Separation of Decisions in Group Identification

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    We study a model of group identification in which individuals’ opinions as to the membership of a group are aggregated to form a list of the group’s members. Potential aggregation rules are studied through the axiomatic approach. We introduce two axioms, meet separability and join separability, each of which requires the list of members generated by the aggregation rule to be independent of whether the question of membership in a group is separated into questions of membership in two other groups. We use these axioms to characterize a class of “one vote” rules, in which one opinion determines whether an individual is considered to be a member of a group. We then use this characterization to provide new axiomatizations of the liberal rule, in which each individual determines for himself whether he is a member of the group, as the only non-degenerate anonymous rule satisfying the meet separability and join separability axioms

    A Group’s a Group, No Matter How Small: An Economic Analysis of Defamation

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    Consider the following: A Jews-for-Jesus bulletin reports, falsely, that a Jewish woman became “a believer in the tenets, the actions, and the philosophy of Jews for Jesus.” Does this publication constitute defamation? Should defamatoriness be determined in accordance with the views of the general non- Jewish community, with those of the Jewish minority, or with a normative ethical commitment? Our Article aims to provide the answers. Part I demonstrates that the de finition of defamatoriness in common law jurisdictions is essentially empirical and distinguishes between the two leading tests—the English test and the American test. Part II.A describes the English, or general community test, whereby a statemen t is defamatory if considered so by the “right thinking members of the public at large.” Part II.B details the American, or sectorial test, whereby a statement is defamatory if considered so by a substantial and respectable minority. A third possible empirical test, whereby the defamatory potential of a statement may be tested within a small group, has not been adopted in any jurisdiction. Part III, however, demonstrates that the small group test is an economically preferable option to both the English and American tests. Part III conducts two separate economic analyses of the alternative empirical tests for defamation. First, we study the relationship between the view of the community and the views of the individuals who comprise the community. We show that the defamation cases should be decided according to the unanimity rule: A statement may be conside red defamatory only when all individuals in the relevant community consider it so. Because this rule is implausible except in the case of the small group test, it suggests that both the English and American tests lack a solid theoretical foundation. Second, we study the costs and benefits associated with the various tests and find that the American sectorial test is no longer optimal. As a result, we argue that it is preferable to adopt the small group test when deciding cases of defamation

    Ultrafast electroabsorption dynamics in an InAs quantum dot saturable absorber at 1.3 mu m

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    The authors report a direct measurement of the absorption dynamics in an InAs p-i-n ridge waveguide quantum dot modulator. The carrier escape mechanisms are investigated via subpicosecond pump-probe measurements at room temperature, under reverse bias conditions. The optical pulses employed are degenerate in wavelength with the quantum dot ground state transition at 1.28 mu m. The absorption change recovers with characteristic times ranging from 62 ps (0 V) to similar to 700 fs (-10 V), showing a decrease of nearly two orders of magnitude. The authors show that at low applied fields, this recovery is attributed to thermionic emission while for higher applied fields, tunneling becomes the dominant mechanism. (c) 2006 American Institute of Physics.</p

    Decreasing Impatience

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    Decreasing impatience, a common behavioral phenomenon in intertemporal choice, and a property with certain normative support in the literature on project evaluation, is characterized in several different ways. Discount factors that display decreasing impatience are characterized through a convexity axiom for investments at fixed interest rates. Then we show that they are equivalent to a geometric average of generalized quasi-hyperbolic discount rates. Finally, they emerge as prices in parimutuel betting markets, that is as the outcome of parimutuel aggregation

    Improving Resolution and Understanding Controls on GPR Response in Carbonate Strata: Implications for Attribute Analysis

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    This is the publisher's version, also available electronically from "http://mr.crossref.org".For more than a decade, environmental, engineering, groundwater, and shallow stratigraphic studies have demonstrated and advanced the usefulness of ground-penetrating radar (GPR) in lithified and unconsolidated sedimentary deposits (e.g., see Neal, 2004 and references therein). Despite the advances, important questions still remain on factors that control the actual appearance and characteristics of GPR reflections and diffractions in any given setting. ?? 2007 Society of Exploration Geophysicists

    Observation of the Cabibbo-suppressed charmed baryon decay Λ_c^+→pφ

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    We report the observation of the Cabibbo-suppressed decays Λ_c^+→pK^-K^+ and Λ_c^+→pφ using data collected with the CLEO II detector at CESR. The latter mode, observed for the first time with significant statistics, is of interest as a test of color suppression in charm decays. We have determined the branching ratios for these modes relative to Λ_c^+→pK^-π^+ and compared our results with theory

    An X-Ray View of the Jet-Cycle in the Radio Loud AGN 3C120

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    We present a study of the central engine in the broad-line radio galaxy 3C120 using a multi-epoch analysis of a deep XMM-Newton observation and two deep Suzaku pointings (in 2012). In order to place our spectral data into the context of the disk-disruption/jet-ejection cycles displayed by this object, we monitor the source in the UV/X-ray bands, and in the radio band. We find three statistically acceptable spectral models, a disk-reflection model, a jet-model and a jet+disk model. Despite being good descriptions of the data, the disk-reflection model violates the radio constraints on the inclination, and the jet-model has a fine-tuning problem, requiring a jet contribution exceeding that expected. Thus, we argue for a composite jet+disk model. Within the context of this model, we verify the basic predictions of the jet-cycle paradigm, finding a truncated/refilling disk during the Suzaku observations and a complete disk extending down to the innermost stable circular orbit (ISCO) during the XMM-Newton observation. The idea of a refilling disk is further supported by the detection of the ejection of a new jet knot approximately one month after the Suzaku pointings. We also discover a step-like event in one of the Suzaku pointings in which the soft band lags the hard band. We suggest that we are witnessing the propagation of a disturbance from the disk into the jet on a timescale set by the magnetic field.Comment: 14 pages, 10 figures, accepted for publication in Ap

    Toxicity of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in the developing male Wistar(Han) rat II: chronic dosing causes developmental delay

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    We have investigated whether fetal exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) causes defects in the male reproductive system of the rat, using chronically exposed rats to ensure continuous exposure of the fetus. 5-6 week old rats were exposed to control diet, or diet containing TCDD, to attain an average dose of 2.4, 8 and 46 ng TCDD kg-1 day-1 for twelve weeks, whereupon the rats were mated, and allowed to litter; rats were switched to control diet after parturition. Male offspring were allowed to develop until kills on PND70 (25 per group), or PND120 (all remaining animals). Offspring from the high dose group showed an increase in total litter loss, and the number of animals alive on post-natal day (PND) 4 in the high dose group was ~26% less than control. The high and medium dose offspring showed decreased weights at various ages. Balano-preputial separation was significantly delayed in all three dose groups, compared to control. There were no significant effects of maternal treatment when the offspring were subjected to a functional observational battery, or learning tests, with the exception that the high dose group showed a deficit in motor activity. 20 rats per group were mated to females, and there were no significant effects of maternal treatment on the fertility of these rats, nor on the F1 or F2 sex ratio. Sperm parameters at PND70 and 120 showed no significant effect of maternal treatment, with the exception that there was an increase in the proportion of abnormal sperm in the high dose group at PND70; this is associated with the developmental delay in puberty in this dose group. There were no remarkable findings of maternal treatment on organ weights, with the exception that testis weights were reduced by ~10% at PND70 (but not PND120), and although the experiment was sufficiently powered to detect small changes, ventral prostate weight was not reduced. There were no significant effects of maternal treatment upon histopathological comparison of high dose and control group organs. These data confirm that developmental exposure to TCDD shows no potent effect on adult sperm parameters or accessory sexual organs, but show that delay in BPS occurs after exposure to low doses of TCDD, and this is dependent upon whether TCDD is administered acutely or chronically

    Extended X-Ray Emission from QSOs

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    We report Chandra ACIS observations of the fields of 4 QSOs showing strong extended optical emission-line regions. Two of these show no evidence for significant extended X-ray emission. The remaining two fields, those of 3C 249.1 and 4C 37.43, show discrete (but resolved) X-ray sources at distances ranging from ~10 to ~40 kpc from the nucleus. In addition, 4C 37.43 also may show a region of diffuse X-ray emission extending out to ~65 kpc and centered on the QSO. It has been suggested that extended emission-line regions such as these may originate in the cooling of a hot intragroup medium. We do not detect a general extended medium in any of our fields, and the upper limits we can place on its presence indicate cooling times of at least a few 10^9 years. The discrete X-ray emission sources we detect cannot be explained as the X-ray jets frequently seen associated with radio-loud quasars, nor can they be due to electron scattering of nuclear emission. The most plausible explanation is that they result from high-speed shocks from galactic superwinds resulting either from a starburst in the QSO host galaxy or from the activation of the QSO itself. Evidence from densities and velocities found from studies of the extended optical emission around QSOs also supports this interpretation.Comment: Accepted by ApJ. 9 pages including 5 figure
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