34,038 research outputs found
MODELING COUPON VALUES FOR READY-TO-EAT BREAKFAST CEREALS
A theoretical framework is developed to highlight the significant determinants of coupon values. A fixed effects panel data model is fitted with data from the breakfast cereal industry. The explanatory variables include own retail price, brand loyalty, brand market share, rival coupon redemptions, and firm and product type indicators.coupons, ready-to-eat breakfast cereals, panel data model, Consumer/Household Economics, Research Methods/ Statistical Methods,
Total-dose radiation effects data for semiconductor devices. 1985 supplement. Volume 2, part A
Steady-state, total-dose radiation test data, are provided in graphic format for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. This volume provides data on integrated circuits. The data are presented in graphic, tabular, and/or narrative format, depending on the complexity of the integrated circuit. Most tests were done using the JPL or Boeing electron accelerator (Dynamitron) which provides a steady-state 2.5 MeV electron beam. However, some radiation exposures were made with a Cobalt-60 gamma ray source, the results of which should be regarded as only an approximate measure of the radiation damage that would be incurred by an equivalent electron dose
Total-dose radiation effects data for semiconductor devices: 1985 supplement, volume 1
Steady-state, total-dose radiation test data are provided, in graphic format, for use by electronic designers and other personnel using semiconductor devices in a radiation environment. The data were generated by JPL for various NASA space programs. The document is in two volumes: Volume 1 provides data on diodes, bipolar transistors, field effect transistors, and miscellaneous semiconductor types, and Volume 2 provides total-dose radiation test data on integrated circuits. Volume 1 of this 1985 Supplement contains new total-dose radiation test data generated since the August 1, 1981 release date of the original Volume 1. Publication of Volume 2 of the 1985 Supplement will follow that of Volume 1 by approximately three months
Multi-agent collaborative search : an agent-based memetic multi-objective optimization algorithm applied to space trajectory design
This article presents an algorithm for multi-objective optimization that blends together a number of heuristics. A population of agents combines heuristics that aim at exploring the search space both globally and in a neighbourhood of each agent. These heuristics are complemented with a combination of a local and global archive. The novel agent-based algorithm is tested at first on a set of standard problems and then on three specific problems in space trajectory design. Its performance is compared against a number of state-of-the-art multi-objective optimization algorithms that use the Pareto dominance as selection criterion: non-dominated sorting genetic algorithm (NSGA-II), Pareto archived evolution strategy (PAES), multiple objective particle swarm optimization (MOPSO), and multiple trajectory search (MTS). The results demonstrate that the agent-based search can identify parts of the Pareto set that the other algorithms were not able to capture. Furthermore, convergence is statistically better although the variance of the results is in some cases higher
Life, Death and Preferential Attachment
Scientific communities are characterized by strong stratification. The highly
skewed frequency distribution of citations of published scientific papers
suggests a relatively small number of active, cited papers embedded in a sea of
inactive and uncited papers. We propose an analytically soluble model which
allows for the death of nodes. This model provides an excellent description of
the citation distributions for live and dead papers in the SPIRES database.
Further, this model suggests a novel and general mechanism for the generation
of power law distributions in networks whenever the fraction of active nodes is
small.Comment: 5 pages, 2 figure
Conservation taxonomy of the Greater Antillean Oriole (Icterus dominicensis): diagnosable plumage variation among allopatric populations supports species status
Allopatric populations, such as those present on islands, pose special challenges to identifying taxonomic boundaries which can be practically addressed using diagnostic criteria. To assess the taxonomic and, hence, conservation status of the four island populations of the Greater Antillean Oriole (Icterus dominicensis), we examined 156 male specimens of I. dominicensis for six discrete and three continuous plumage characters. The four island populations proved to be 100% diagnosable. Icterus d. northropi differed from all other taxa by having the greatest extent of yellow on the venter (non-overlapping with other taxa). Icterus d. portoricensis was distinguished from all other taxa by the presence of a black upper rump (yellow in other taxa) and the least extent of yellow on the rump (non-overlapping with other taxa). Icterus d. melanopsis and I. d. dominicensis were fully discriminated from I. d. northropi and I. d. portoricensis by the aforementioned characters and from each other by upper-tail covert color (black and ≥ 50% yellow, respectively). Our findings support recent studies suggesting that the four island groups represent distinct allospecies consistent with interpretations of both the phylogenetic and evolutionary species concepts. With elevation to full species, conservation priorities need to be revisited, particularly for the critically endangered Bahamas taxon (I. d. northropi)
Adaptive intelligence applied to numerical optimisation
The article presents modification strategies theoretical comparison and experimental results achieved by adaptive heuristics applied to numerical optimisation of several non-constraint test functions. The aims of the study are to identify and compare how adaptive search heuristics behave within heterogeneous search space without retuning of the search parameters. The achieved results are summarised and analysed, which could be used for comparison to other methods and further investigation
Sediment-moss interactions on a temperate glacier: Falljökull, Iceland
Full text of this article can be found at: http://www.igsoc.org/annals/ Copyright IGS. DOI: 10.3189/172756408784700734We present the results of preliminary investigations of globular moss growth on the surface of Falljökull, a temperate outlet glacier of the Vatnajökull ice cap, southern Iceland. Supraglacial debris has provided a basis for moss colonization, and several large (>500 m2) patches of moss growth (Racomitrium spp.) are observed on the surface of the glacier. Each area of moss-colonized supraglacial debris shows a downslope increase in sphericity and moss cushion size and a decrease in percentage surface coverage of moss-colonized and bare clasts. It is suggested that moss growth on supraglacial debris allows preferential downslope movement of clasts through an associated increase in both overall mass and sphericity. Thermal insulation by moss cushions protects the underlying ice surface from melt, and the resulting ice pedestals assist in downslope sliding and toppling of moss cushions. The morphology and life cycle of supraglacial globular mosses is therefore not only closely linked to the presence and distribution of supraglacial debris, but also appears to assist in limited down-glacier transport of this debris. This research highlights both the dynamic nature of the interaction of mosses with supraglacial sedimentary systems and the need for a detailed consideration of their role within the wider glacial ecosystem.Peer reviewe
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An ECOOP web portal for visualising and comparing distributed coastal oceanography model and in situ data
As part of a large European coastal operational oceanography project (ECOOP), we have developed a web portal for the display and comparison of model and in situ marine data. The distributed model and in situ datasets are accessed via an Open Geospatial Consortium Web Map Service (WMS) and Web Feature Service (WFS) respectively. These services were developed independently and readily integrated for the purposes of the ECOOP project, illustrating the ease of interoperability resulting from adherence to international standards. The key feature of the portal is the ability to display co-plotted timeseries of the in situ and model data and the quantification of misfits between the two. By using standards-based web technology we allow the user to quickly and easily explore over twenty model data feeds and compare these with dozens of in situ data feeds without being concerned with the low level details of differing file formats or the physical location of the data. Scientific and operational benefits to this work include model validation, quality control of observations, data assimilation and decision support in near real time. In these areas it is essential to be able to bring different data streams together from often disparate locations
The resurrection of group selection as a theory of human cooperation
Two books edited by members of the MacArthur Norms and Preferences Network (an interdisciplinary group, mainly anthropologists and economists) are reviewed here. These books in large part reflect a renewed interest in group selection
that has occurred among these researchers: they promote the theory that human cooperative behavior evolved via selective processes which favored biological and/or cultural group-level adaptations as opposed to individual-level adaptations. In support of this theory, an impressive collection of cross-cultural data are presented which suggest that participants in experimental economic games often do not behave as self-interested income maximizers; this lack of self-interest is regarded as evidence of group selection. In this review, problems with these data and with the theory are discussed. On the data side, it is argued that even if a behavior seems individually-maladaptive in a game context, there is no reason to believe that it would have been that way in ancestral contexts, since the environments of experimental games do not at all resemble those in which ancestral humans would have interacted cooperatively. And on the theory side, it is argued that it is premature to invoke group selection in order to explain human cooperation, because more parsimonious individual-level theories have not yet been exhausted. In summary, these books represent ambitious interdisciplinary contributions on an important topic, and they include unique and useful data; however, they do not make a convincing case that the evolution of human cooperation required group selection
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