1,721,382 research outputs found
Tóth Kálmán válogatott kőlteményei /
No full text"Magyar művészek rajzaival."Includes indexes.Mode of access: Internet
Why is equity order flow so persistent?
No full textOrder flow in equity markets is remarkably persistent in the sense that order signs (to buy or sell) are positively autocorrelated out to time lags of tens of thousands of orders, corresponding to many days. Two possible explanations are herding, corresponding to positive correlation in the behavior of different investors, or order splitting, corresponding to positive autocorrelation in the behavior of single investors. We investigate this using order flow data from the London Stock Exchange for which we have membership identifiers. By formulating models for herding and order splitting, as well as models for brokerage choice, we are able to overcome the distortion introduced by brokerage. On timescales of less than a few hours the persistence of order flow is overwhelmingly due to splitting rather than herding. We also study the properties of brokerage order flow and show that it is remarkably consistent both cross-sectionally and longitudinally
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Water retention of salt affected soils: quantitative estimation using soil survey information
No full textSoil water retention (SWR) at -0.1, -33, -1500 and -150000 kPa matric potentials and available water content (AWC) were estimated from information available from 729 horizons of salt-affected soils in the Hungarian Detailed Soil Hydrophysical Database. Soil characteristics of the 1:10,000 scale Hungarian soil maps were used as input parameters. Ordinal and nominal (categorical) variables: texture, organic matter content, calcium carbonate content, soluble salt content, pH and soil subtype classes of the soil map were used to develop a new prediction method based on the CHAID classification tree. Results of the model development were compared with results using conventional prediction methods (CRT – classification tree and multiple linear regression). Four types of pedotransfer rules were established by classification tree methods. The first rule uses contiuous-type input parameters, the second uses soil taxonomical information in addition, the third and fourth one uses categorical-type input parameters. In addition, continuous pedotransfer functions (point estimations) were established as well. Results show that the root mean square error (RMSE) of the pedotransfer rules based on categorical-type soil information is between 1.25 vol% (at -150000 kPa) and 6.40 vol% (-33 kPa). Model performance of pedotransfer rules and pedotransfer functions was not significantly different, meaning that with the mentioned available input parameters, for salt-affected soils the prediction accuracy is similar with categorical and continuous-type information. The established methods can be readily used to prepare available water content maps for the topsoil of salt affected soils based on solely soil survey information.JRC.H.5 - Land Resources Managemen
Leaders Are More Attractive: Birds with Bigger Yellow Breast Patches Are Followed by More Group-Mates in Foraging Groups
Get PDFSocial network theory provides a perfect tool to better understand the population-level consequences of how individuals interact and make their decisions; however, this approach is generally overlooked among evolutionary biologists interested in social relationships. Here, we used social network analysis to examine the patterns of leader-follower interactions in relation to individual characteristics in foraging groups of free-living rock sparrows (Petronia petronia). We found that yellow feather ornamentation, a carotenoid-based trait, was the best predictor of leadership: birds with bigger ornaments exerted greater influence in the foraging groups and were followed by more group-mates than less elaborate individuals. An individual's tendency for eliciting followings was not influenced by sex, condition or the level of parental investment. None of the above individual characteristics had significant effect on the tendency of individuals to follow others. Our results indicate that a sexually selected trait can also play a significant role in group coordination and social organization of a species
Low-temperature storage of Exorista larvarum puparia as a tool for assisting parasitoid production
Get PDFTachinid parasitoids deserve to be better exploited as natural enemies of insect pests. The development of efficient mass-rearing techniques for these entomophagous insects may encourage their use in biological control programs. Exorista larvarum (L.) (Diptera: Tachinidae) is a Palearctic species, which has been introduced in northern America for the control of the gypsy moth, Lymantria dispar (L.). The potential use of this polyphagous parasitoid of Lepidoptera against other forest and agricultural pests encourages research aimed at the improvement of techniques for its rearing, including protocols for storage at low temperature. This technology allows a certain degree of control over the speed of development of the stored insects and assists mass-rearing facilities that have to match production with demand, especially during field outbreaks of pests. With the aim of developing storage protocols for E. larvarum, we investigated the effects of storage for 1–4 weeks of 1-day-old puparia at 15 °C. Lower temperatures (5 and 10 °C) and longer storage periods were excluded following the outcome of preliminary experiments. Parasitoid emergence and quality control parameters of the female flies obtained from the stored puparia were evaluated. In addition, female lipid body reserves were measured. The temperature of 15 °C proved to be suitable for all the durations tested, although some detrimental effects were observed following storage (e.g., lower longevity and fecundity). Our findings may prove useful to increase the flexibility of E. larvarum colony management
Optimal Design of Lattice Domes by Means of a Constrained Force Density Method
Get PDFIn this contribution the design of reticulated domes is dealt with, exploring the optimal
solutions that can be retrieved by a form-finding approach. To this goal a numerical
tool is implemented to address the design of reticulated shells through funicular
analysis. The force density method is implemented to cope with the equilibrium of
reticulated shells whose branches are required to behave as bars. Optimal networks
are sought by coupling the force density method with techniques of sequential convex
programming that were originally conceived to handle formulations of size optimization
for elastic structures. The Maxwell number, which is the sum of the force-timeslength
products for all the branches in the spatial network, is used as objective function
to be minimized, whereas constraints on the length of the branches are enforced. Funicular
networks that are fully feasible with respect to the set of local enforcements
are retrieved in a limited number of iterations, with no need to initialize the procedure
with a feasible starting guess. Optimal solutions are explored, considering different
types of grids, i.e. different types of lattices, while considering self-weight
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