6,278 research outputs found
The emergence of property rights enforcement in early trade : A behavioral model without reputational effects
Original article can be found at: http://www.sciencedirect.com/ Copyright ElsevierThe present article focuses on the conditions that allow governments to increase property rights protection because they expect enough income from such action. We develop a behavioral explanation, according to which the answer lies in the growth in the importance, size and wealth of merchant guilds in the medieval era in Western Europe as well as a somewhat surprising effect of volatile price structures. We add to prior research by showing that even uncoordinated embargo pressures among multiple guilds could get medieval rulers to offer high levels of property rights protection. © 2008 Elsevier B.V. All rights reserved.Peer reviewe
Dismantling Lamarckism: why descriptions of socio-economic evolution as Lamarckian are misleading
“The original publication is available at www.springerlink.com”. Copyright Springer.This paper addresses the widespread tendency to describe socio-economic evolution as Lamarckian. The difference between Lamarckian and Darwinian replication is clarified. It is shown that a phenotype-genotype distinction must first be established before we can identify Lamarckian transmission. To qualify as Lamarckian inheritance, acquired properties at the phenotypic level must be encoded in a genotype that is passed on to the next generation. Some possible social replicators (or genotypes) are identified, with a view to exploring possible distinctions between genotype and phenotype at the social level. It is concluded that the Lamarckian label does not readily transfer to socio-economic evolution, despite the fact that social genotypes (such as routines) may adapt within any given phenotype (such as an organisation). By contrast, no such problems exist with the description of socio-economic evolution as Darwinian.Peer reviewe
Integrating case-based reasoning and hypermedia documentation: an application for the diagnosis of a welding robot at Odense steel shipyard
Reliable and effective maintenance support is a vital consideration for the management within today's manufacturing environment. This paper discusses the development of a maintenance system for the world's largest robot welding facility. The development system combines a case-based reasoning approach for diagnosis with context information, as electronic on-line manuals, linked using open hypermedia technology. The work discussed in this paper delivers not only a maintenance system for the robot stations under consideration, but also a design framework for developing maintenance systems for other similar applications
Derating a single wind farm turbine for reducing its wake and fatigue
Derating of individual turbines is one of the options to implement wind farm performance optimization, although there are different ways to proceed with such derating at the turbine control level. The present paper develops an option based on the minimal thrust coefficient in accordance with the Cp and C t contour levels. This strategy is compared for the region below rated wind speed with two other strategies where either the pitch or the tip speed ratio are maintained at their maximum C p values from normal operation. The study concludes that maintaining the pitch at the optimal value from normal operation produces poorer performance from the thrust and the loads perspective. Practical implementation issues have also been detected
Detection of CO from SMM J16359+6612, The Multiply Imaged Submillimeter Galaxy Behind A2218
We report the detection of CO (=32) line emission from all three
multiple images (A,B and C) of the intrinsically faint ( 0.8 mJy)
submillimeter-selected galaxy SMM J16359+6612. The brightest source of the
submm continuum emission (B) also corresponds to the brightest CO emission,
which is centered at =2.5168, consistent with the pre-existing redshift
derived from \Ha. The observed CO flux in the A, B and C images is 1.2, 3.5 and
1.6 Jy \kms respectively, with a linewidth of \kms. After
correcting for the lensing amplification, the CO flux corresponds to a
molecular gas mass of \Msun, while the
extent of the CO emission indicates that the dynamical mass of the system
\Msun. Two velocity components are seen in the CO spectra;
these could arise from either a rotating compact ring or disk of gas, or
merging substructure. The star formation rate in this galaxy was previously
derived to be 100--500 \Msun \yr. If all the CO emission arises from the
inner few kpc of the galaxy and the galactic CO-to-H conversion factor
holds, then the gas consumption timescale is a relatively short 40 Myr, and so
the submm emission from SMM J16359+6612 may be produced by a powerful, but
short-lived circumnuclear starburst event in an otherwise normal and
representative high-redshift galaxy.Comment: Appearing in the 2004 October 10 issue of the Astrophysical Journal
Letters, Volume 614, L5-L
Does the Superior Colliculus Control Perceptual Sensitivity or Choice Bias during Attention? Evidence from a Multialternative Decision Framework
Distinct networks in the forebrain and the midbrain coordinate to control spatial attention. The critical involvement of the superior colliculus (SC)—the central structure in the midbrain network—in visuospatial attention has been shown by four seminal, published studies in monkeys (Macaca mulatta) performing multialternative tasks. However, due to the lack of a mechanistic framework for interpreting behavioral data in such tasks, the nature of the SC's contribution to attention remains unclear. Here we present and validate a novel decision framework for analyzing behavioral data in multialternative attention tasks. We apply this framework to re-examine the behavioral evidence from these published studies. Our model is a multidimensional extension to signal detection theory that distinguishes between two major classes of attentional mechanisms: those that alter the quality of sensory information or “sensitivity,” and those that alter the selective gating of sensory information or “choice bias.” Model-based simulations and model-based analyses of data from these published studies revealed a converging pattern of results that indicated that choice-bias changes, rather than sensitivity changes, were the primary outcome of SC manipulation. Our results suggest that the SC contributes to attentional performance predominantly by generating a spatial choice bias for stimuli at a selected location, and that this bias operates downstream of forebrain mechanisms that enhance sensitivity. The findings lead to a testable mechanistic framework of how the midbrain and forebrain networks interact to control spatial attention
Experimental investigation of the Landau-Pomeranchuk-Migdal effect in low-Z targets
In the CERN NA63 collaboration we have addressed the question of the
potential inadequacy of the commonly used Migdal formulation of the
Landau-Pomeranchuk-Migdal (LPM) effect by measuring the photon emission by 20
and 178 GeV electrons in the range 100 MeV - 4 GeV, in targets of
LowDensityPolyEthylene (LDPE), C, Al, Ti, Fe, Cu, Mo and, as a reference
target, Ta. For each target and energy, a comparison between simulated values
based on the LPM suppression of incoherent bremsstrahlung is shown, taking
multi-photon effects into account. For these targets and energies, we find that
Migdal's theoretical formulation is adequate to a precision of better than
about 5%, irrespective of the target substance.Comment: 8 pages, 13 figure
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