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Range searching in low-density environments

Otfried Schwarzkopf, Jules Vleugels
1996 Information Processing Letters  
We de ne a set of arbitrarily-shaped objects in R d to be a low-density environment if any axis-parallel hypercube intersects only few objects of comparable or larger size.  ...  range searching queries with query ranges of size comparable to the smallest object.  ...  Theorem 4.1 Let E be a k-low-density environment in R d .  ... 
doi:10.1016/s0020-0190(96)00154-8 fatcat:iywphkjlynfxfmmlmjumotlys4

Subspace Approach to Inversion by Genetic Algorithms Involving Multiple Frequencies

Purnima Ratilal, Peter Gerstoft, Joo Thiam Goh
1998 Journal of Computational Acoustics  
In each subspace Genetic Algorithms are used for the optimization, it provides exibility to search over a wide range of parameters and also helps in selecting data sets to be used in the inversion.  ...  At low frequencies it is mainly the bottom parameters that are most sensitive and at high frequencies the geometric parameters are the most sensitive.  ...  Here we use several low frequencies to probe the sediment and bottom. As shown in Sec. 3.2, the low frequencies are less sensitive to variations in the source range and depth.  ... 
doi:10.1142/s0218396x98000090 fatcat:j4wt45i3dzf5bfzsgsfhqsfnj4

The influence of the environment on Lévy random search efficiency: Fractality and memory effects

A.S. Ferreira, E.P. Raposo, G.M. Viswanathan, M.G.E. da Luz
2012 Physica A: Statistical Mechanics and its Applications  
An open problem in the field of random searches relates to optimizing the search efficiency in fractal environments.  ...  the rate of target findings in random searches.  ...  target sites in the low-density regime.  ... 
doi:10.1016/j.physa.2012.01.028 fatcat:siqicnwtpnd4zgaumnfmbdbblq

A search for LSB dwarf galaxies in various environments [article]

Sarah Roberts, Jonathan Davies, Sabina Sabatini
2003 arXiv   pre-print
In this paper we present results from a survey conducted in different environments to search for low surface brightness (LSB) dwarf galaxies.  ...  The varying dwarf galaxy populations in different environments poses a problem for Cold Dark Matter (CDM) hierarchical clustering models.  ...  Table 1 . 1 Summary of results for the three surveys, compared with predictions from CDM Environment Description DGR 1 MGS Passes through regions of high and low density 6:1 UMa Low density cluster  ... 
arXiv:astro-ph/0310547v1 fatcat:cdthajrtafabtihgjs6gaaekpq

Exploratory behaviour of colonizing rats in novel environments

James C. Russell, Angus J.C. McMorland, Jamie W.B. MacKay
2010 Animal Behaviour  
Random movement and increased ranges at low density have implications for understanding animal colonization dynamics and intercepting invasive species arriving at new locations. Ó  ...  We found that (1) individual movements are apparently random; (2) range size increases most rapidly in the first week after arrival; (3) range size is larger than for individuals at high density; (4) movement  ...  from high-to low-density populations and familiar to novel environments (Smith & Morrell 2007) .  ... 
doi:10.1016/j.anbehav.2009.10.020 fatcat:wxtrwsfqfffr5a3pnjvjl2exse

Changes in the home range sizes of terrestrial vertebrates in response to urban disturbance: a meta-analysis

Kate O'Donnell, Javier delBarco-Trillo
2020 Journal of Urban Ecology  
We calculated effect sizes as the difference in animal home range sizes between natural and urban environments.  ...  and density of resources.  ...  Species often occur in much higher densities in urban areas than in rural environments (Walton et al. 2017) .  ... 
doi:10.1093/jue/juaa014 fatcat:zr2jvzdyhfd4ncytc56o75owvi

Sensory Information and Encounter Rates of Interacting Species

Andrew M. Hein, Scott A. McKinley, Claus O. Wilke
2013 PLoS Computational Biology  
n is the dimension of the environment) when prey density is low.  ...  Thus, in both the high-information extreme of long-distance directional sensing, and the low-information extreme of noisy non-directional sensing, encounter rate kinetics differ qualitatively from those  ...  Casas, and the Biomath group in the Department of Mathematics at the University of Florida. Author Contributions Conceived and designed the experiments: AMH SAM. Performed the experiments: AMH.  ... 
doi:10.1371/journal.pcbi.1003178 pmid:23966847 pmcid:PMC3744405 fatcat:rxccyfz3gvdwjnzjogcpinpx3e

A search for LSB dwarf galaxies in various environments

Sarah Roberts, Jonathan Davies, Sabina Sabatini
2004 Symposium - International astronomical union  
environments to search for low surface brightness (LSB) dwarf galaxies.  ...  The varying dwarf galaxy populations in different environments pose a problem for Cold Dark Matter (CDM) hierarchical clustering models. in this paper we present results from a survey conducted in different  ...  Summary of results for the three surveys, compared with predictions from CDM Environment Description DGR MGS Passes through regions of high and low density 6:1 UMa Low density cluster - Virgo  ... 
doi:10.1017/s0074180900183603 fatcat:nxwcz3kgwzcb7a4ud6n2qurqt4

Do spatial models of growth rate potential reflect fish growth in a heterogeneous environment? A comparison of model results

J. A. Tyler, S. B. Brandt
2001 Ecology of Freshwater Fish  
The results from a simulation experiment show that changes in the model environment that caused changes in the average growth rate potential correlated extremely highly (r22=0.97) with changes in simulated  ...  Do spatial models of growth rate potential reflect fish growth in a heterogeneous environment? A comparison of model results.  ...  Sprules helped supply information on the zooplankton population and water temperatures of Lake Ontario used to describe the model environment.  ... 
doi:10.1034/j.1600-0633.2001.100106.x fatcat:uorfuwealbgqrbi3mlnha4bk7y

Toward understanding environmental effects in SDSS clusters

J. Einasto, E. Tago, M. Einasto, E. Saar, I. Suhhonenko, P. Heinämäki, G. Hütsi, D. L. Tucker
2005 Astronomy and Astrophysics  
We also study clusters and superclusters in numerical simulations. Simulated clusters in a high-density environment are also more massive than those in a low-density environment.  ...  We determine the luminosity function of clusters and find that clusters in a high-density environment have a luminosity a factor of ~5 higher than in a low-density environment.  ...  We are indebted to the SDSS team for their efforts in carrying the Survey and making its results available to the astronomical community. P.H. was supported by the Jenny and Antti Wihuri foundation.  ... 
doi:10.1051/0004-6361:20042347 fatcat:lgpvqnz7ozhlfm2i3yh6ozund4

The Effect of Exploration on the Use of Producer-Scrounger Tactics

Ralf H. J. M. Kurvers, Steven Hamblin, Luc-Alain Giraldeau, Sean A. Rands
2012 PLoS ONE  
In high predation environments fast exploring individuals were selected for but only at low to intermediate patch densities. Predation did not affect scrounging behavior.  ...  Our simulations show that under conditions of low patch densities slow exploring scroungers were favored whereas high patch density favored fast exploring individuals that either produced (at low patch  ...  In high predation environments slow exploring individuals were selected for but only at low to intermediate patch densities.  ... 
doi:10.1371/journal.pone.0049400 pmid:23185327 pmcid:PMC3503990 fatcat:zq6d5bpclzeuhevxhmsmp4pe2y

Local interactions between predators and prey call into question commonly used functional responses

Toshinori Okuyama
2009 Ecological Modelling  
In other other words, aN (a is the baseline encounter rate and N is prey density) describes the encounter rate.  ...  Predators were assumed to possess a spatial perception range that influenced their foraging behavior (e.g., if a prey is in the perception range, the predator moves towards the prey).  ...  Furthermore, when predators' perception range is high, even when prey density is low, there is already a high probability that a prey is in its perception range (i.e., weak spatial effect), and thus the  ... 
doi:10.1016/j.ecolmodel.2009.02.010 fatcat:tt7ufwxhazb43bpprrukx5zrvm

Page 16 of Astronomy and Astrophysics Vol. 178, Issue 1-2 [page]

1987 Astronomy and Astrophysics  
Also it seemed preferable to select a region with a known and narrow extension in redshift space, so that we could restrict the search range in velocity and make use of a more sensitive radiotelescope  ...  At least in these particular cases the limit can be set in the range 10° °-10~° times any reasonable value of the closure density (p, = 3H2/8G, hereafter H, = 75kms_ ' Mpc”).  ... 

Clusters and Superclusters in the Sloan Survey [article]

J. Einasto, E. Tago, M. Einasto, E. Saar
2004 arXiv   pre-print
We found that galaxies and clusters in a high-density environment have luminosities that are five to ten times higher than in a low-density environment.  ...  Density fields with smoothing lengthst of 10 and 0.8 Mpc/h are calculated.  ...  than the masses of most massive clusters in low-density environments.  ... 
arXiv:astro-ph/0408463v1 fatcat:o63kbtfsqreb7fuyjn7jv2kxmi

Approximate algorithms for static and continuous range queries in mobile navigation

Haidar AL-Khalidi, David Taniar, Maytham Safar
2012 Computing  
Finally, if the density of the objects is very high, the performance of the range search technique will dramatically decrease.  ...  One of the most frequently used queries in such applications is range search query (RSQ) [1].  ...  The source of our implementations can be downloaded from the following URL: http://users.monash.edu/~dtaniar/Approx-Range-Computing-Journal.  ... 
doi:10.1007/s00607-012-0219-7 fatcat:kwqc3wdghretjfaysjv2a3emfm
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