scholarly journals Movement analyses of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae)

2009 ◽  
Vol 100 (6) ◽  
pp. 623-634 ◽  
Author(s):  
N.C. Brouwers ◽  
A.C. Newton
Keyword(s):  
Random Walk ◽  
Leaf Litter ◽  
Ground Surface ◽  
Movement Pattern ◽  
Bare Soil ◽  
Dispersal Ability ◽  
Heterogeneous Environments ◽  
Population Spread ◽  
Over Time ◽  
Nemobius Sylvestris

AbstractInformation on the dispersal ability of invertebrate species associated with woodland habitats is severely lacking. Therefore, a study was conducted examining the movement patterns of wood cricket (Nemobius sylvestris) (Orthoptera: Gryllidae) on the Isle of Wight, UK. Juvenile (i.e. nymphs) and adult wood crickets were released and observed over time within different ground surface substrates. Their movement paths were recorded and subsequently analysed using random walk models. Nymphs were found to move more slowly than adults did; and, when given a choice, both nymphs and adults showed a preference for moving through or over leaf litter compared to bare soil or grass. A correlated random walk (CRW) model accurately described the movement pattern of adult wood crickets through leaf litter, indicating a level of directional persistence in their movements. The estimated population spread through leaf litter for adults was 17.9 cm min−1. Movements of nymphs through leaf litter could not accurately be described by a random walk model, showing a change in their movement pattern over time from directed to more random movements. The estimated population spread through leaf litter for nymphs was 10.1 cm min−1. The results indicate that wood cricket adults can be considered as more powerful dispersers than nymphs; however, further analysis of how the insects move through natural heterogeneous environments at a range of spatio-temporal scales needs to be performed to provide a complete understanding of the dispersal ability of the species.

A point-based Bayesian hierarchical model to predict the outcome of tennis matches

2019 ◽  
Vol 15 (4) ◽  
pp. 313-325 ◽  
Author(s):  
Martin Ingram
Keyword(s):  
Random Walk ◽  
Hierarchical Model ◽  
Bayesian Hierarchical Model ◽  
Bayesian Hierarchical ◽  
Gaussian Random Walk ◽  
Over Time ◽  
Modelling Approach ◽  
Independent And Identically Distributed

Abstract A well-established assumption in tennis is that point outcomes on each player’s serve in a match are independent and identically distributed (iid). With this assumption, it is enough to specify the serve probabilities for both players to derive a wide variety of event distributions, such as the expected winner and number of sets, and number of games. However, models using this assumption, which we will refer to as “point-based”, have typically performed worse than other models in the literature at predicting the match winner. This paper presents a point-based Bayesian hierarchical model for predicting the outcome of tennis matches. The model predicts the probability of winning a point on serve given surface, tournament and match date. Each player is given a serve and return skill which is assumed to follow a Gaussian random walk over time. In addition, each player’s skill varies by surface, and tournaments are given tournament-specific intercepts. When evaluated on the ATP’s 2014 season, the model outperforms other point-based models, predicting match outcomes with greater accuracy (68.8% vs. 66.3%) and lower log loss (0.592 vs. 0.641). The results are competitive with approaches modelling the match outcome directly, demonstrating the forecasting potential of the point-based modelling approach.

Foraging behaviour of Armadillidium vulgare (Isopoda: Oniscidea) in heterogeneous environments

Behaviour ◽  
2004 ◽  
Vol 141 (2) ◽  
pp. 233-244 ◽  
Author(s):  
Joanne Tuck ◽  
Mark Hassall
Keyword(s):  
Leaf Litter ◽  
Foraging Behaviour ◽  
Walking Speed ◽  
Optimal Foraging Theory ◽  
Heterogeneous Environments ◽  
Intake Rate ◽  
High Quality ◽  
Turning Angle ◽  
Quality Food ◽  
Armadillidium Vulgare

AbstractForaging behaviour of Armadillidium vulgare was observed in laboratory arenas in which the spatial distribution of patches of high quality food (powdered dicotyledonous leaf litter) was varied within a background of low quality food (powdered grass leaf litter). The hypotheses that the foraging behaviour and foraging path of A. vulgare would be influenced by food quality and the patchiness of high quality food resources were tested. More time was spent in high quality food patches than in low quality food backgrounds than expected by chance in all heterogeneity treatments, but an increasingly higher percentage of time was spent in low quality food as the high quality food became more clumped in space. More time was spent searching, but less time was spent feeding in low quality food backgrounds than in high quality food patches in all the treatments. Walking speed was found to be lower in high quality food patches than in low quality food backgrounds and this was not affected by treatment. Turning frequency and turning angle were found to be higher in high quality food patches than in low quality backgrounds. Turning frequency in low quality food backgrounds decreased as the high quality food became more clumped in space, whereas turning angle in high quality food patches significantly increased in the patchy, but then decreased again in the clumped treatment. The effects of varying the spatial heterogeneity of high quality foods on the trade-off between costs of searching and intake benefits for saprophages are discussed in relation to predictions from optimal foraging theory for circumstances when intake rate maximisation is affected by the constraint of limited nutrients.

scholarly journals Ecological relations between mangrove leaf litter and the spatial distribution of the gastropod Melampus coffeus in a fringe mangrove forest

2015 ◽  
Vol 105 (1) ◽  
pp. 35-40 ◽  
Author(s):  
Diva S. Tavares ◽  
Rafaela C. Maia ◽  
Cristina Rocha-Barreira ◽  
Helena Matthews-Cascon
Keyword(s):  
Spatial Distribution ◽  
Leaf Litter ◽  
Mangrove Forest ◽  
Atlantic Coast ◽  
Ground Surface ◽  
Mangrove Forests ◽  
Physical Presence ◽  
Ecological Relations ◽  
Melampus Coffeus ◽  
Pulmonate Gastropod

Leaf litter represents a food source to many organisms that may directly contribute to organic matter decomposition. In addition, the physical presence of these vegetal detritus contributes for the modification of some environmental areas and produce microhabitats that may act as a refuge against predators and desiccation for many animals. The pulmonate gastropod Melampus coffeus (Linnaeus, 1758) (Ellobiidae) is a very common specie in Atlantic Coast mangrove forests and feeds on fallen mangrove leaves. It was hypothesized that the spatial distribution of Melampus coffeus is directly affected by mangrove leaf litter biomass deposition. Thus, this research aimed at evaluating the spatial distribution of these gastropods in relation to the biomass of mangrove leaf litter through a twelve-month period. The study area was established in the middle estuary of Pacoti River, state of Ceará, Brazil where two adjacent zones with different topographic profiles were determined. Samples of Melampus coffeus and leaf litter were collected monthly, throughout a year, from the mangrove ground surface. The results indicated that the presence of twigs in mangrove litter favor the occupation by smaller individuals of M. coffeus, probably because smaller individuals are more susceptible to predator attacks and desiccation than larger ones, and twigs and branches may provide a safe microhabitat.

scholarly journals Emission of nitrous acid from soil and biological soil crusts represents an important source of HONO in the remote atmosphere in Cyprus

2018 ◽  
Vol 18 (2) ◽  
pp. 799-813 ◽  
Author(s):  
Hannah Meusel ◽  
Alexandra Tamm ◽  
Uwe Kuhn ◽  
Dianming Wu ◽  
Anna Lena Leifke ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Biological Soil Crust ◽  
Ground Surface ◽  
Field Studies ◽  
Bare Soil ◽  
Biological Soil Crusts ◽  
Soil Crusts ◽  
Wide Range ◽  
Mediterranean Island ◽  
Water Holding

Abstract. Soil and biological soil crusts can emit nitrous acid (HONO) and nitric oxide (NO). The terrestrial ground surface in arid and semiarid regions is anticipated to play an important role in the local atmospheric HONO budget, deemed to represent one of the unaccounted-for HONO sources frequently observed in field studies. In this study HONO and NO emissions from a representative variety of soil and biological soil crust samples from the Mediterranean island Cyprus were investigated under controlled laboratory conditions. A wide range of fluxes was observed, ranging from 0.6 to 264 ng m−2 s−1 HONO-N at optimal soil water content (20–30 % of water holding capacity, WHC). Maximum NO-N fluxes at this WHC were lower (0.8–121 ng m−2 s−1). The highest emissions of both reactive nitrogen species were found from bare soil, followed by light and dark cyanobacteria-dominated biological soil crusts (biocrusts), correlating well with the sample nutrient levels (nitrite and nitrate). Extrapolations of lab-based HONO emission studies agree well with the unaccounted-for HONO source derived previously for the extensive CYPHEX field campaign, i.e., emissions from soil and biocrusts may essentially close the Cyprus HONO budget.

scholarly journals Emission of nitrous acid from soil and biological soil crusts represents a dominant source of HONO in the remote atmosphere in Cyprus

2017 ◽  
Author(s):  
Hannah Meusel ◽  
Alexandra Tamm ◽  
Uwe Kuhn ◽  
Dianming Wu ◽  
Anna Lena Leifke ◽  
...  
Keyword(s):  
Nitrous Acid ◽  
Biological Soil Crust ◽  
Ground Surface ◽  
Field Studies ◽  
Bare Soil ◽  
Biological Soil Crusts ◽  
Soil Crusts ◽  
Wide Range ◽  
Mediterranean Island ◽  
Water Holding

Abstract. Soil and biological soil crusts can emit nitrous acid (HONO) and nitric oxide (NO). The terrestrial ground surface in arid and semi-arid regions is anticipated to play an important role in the local atmospheric HONO budget, deemed to represent one of the unaccounted HONO sources frequently observed in field studies. In this study HONO and NO emissions from a representative variety of soil and biological soil crust samples from the Mediterranean island Cyprus were investigated under controlled laboratory conditions. A wide range of fluxes was observed, ranging from 0.6 to 264 ng m−2 s−1 HONO-N at optimal soil water content (20–30 % of water holding capacity, WHC). Maximum NO-N at this WHC fluxes were lower (0.8–121 ng m−2 s−1). Highest emissions of both reactive nitrogen species were found from bare soil, followed by light and dark cyanobacteria-dominated biological soil crusts (biocrusts), correlating well with the sample nutrient levels (nitrite and nitrate). Extrapolations of lab-based HONO emission studies agree well with the unaccounted HONO source derived previously for the extensive CYPHEX field campaign, i.e., emissions from soil and biocrusts may essentially close the Cyprus HONO budget.

scholarly journals Investing and Stopping

2014 ◽  
Vol 51 (4) ◽  
pp. 898-909
Author(s):  
Moritz Duembgen ◽  
L. C. G. Rogers
Keyword(s):  
Brownian Motion ◽  
Random Walk ◽  
Optimal Stopping ◽  
Numerical Scheme ◽  
Optimization Problem ◽  
Hedge Fund ◽  
Optimal Stopping Problem ◽  
Over Time

In this paper we solve the hedge fund manager's optimization problem in a model that allows for investors to enter and leave the fund over time depending on its performance. The manager's payoff at the end of the year will then depend not just on the terminal value of the fund level, but also on the lowest and the highest value reached over that time. We establish equivalence to an optimal stopping problem for Brownian motion; by approximating this problem with the corresponding optimal stopping problem for a random walk we are led to a simple and efficient numerical scheme to find the solution, which we then illustrate with some examples.

scholarly journals A Distributed Approach to the Evasion Problem

Algorithms ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 149
Author(s):  
Denis Khryashchev ◽  
Jie Chu ◽  
Mikael Vejdemo-Johansson ◽  
Ping Ji
Keyword(s):  
Distributed Algorithm ◽  
Necessary Conditions ◽  
Sufficient Conditions ◽  
Movement Pattern ◽  
Sheaf Theory ◽  
Distributed Approach ◽  
Sufficient And Necessary Conditions ◽  
Evasion Problem ◽  
Over Time ◽  
Path Detection

The Evasion Problem is the question of whether—given a collection of sensors and a particular movement pattern over time—it is possible to stay undetected within the domain over the same stretch of time. It has been studied using topological techniques since 2006—with sufficient conditions for non-existence of an Evasion Path provided by de Silva and Ghrist; sufficient and necessary conditions with extended sensor capabilities provided by Adams and Carlsson; and sufficient and necessary conditions using sheaf theory by Krishnan and Ghrist. In this paper, we propose three algorithms for the Evasion Problem: one distributed algorithm extension of Adams’ approach for evasion path detection, and two different approaches to evasion path enumeration.

scholarly journals Dormancy and germination of the trimorphic achenes of a cold desert annual: spreading the risk over time

AoB Plants ◽  
2020 ◽  
Vol 12 (6) ◽  
Author(s):  
Juanjuan Lu ◽  
Wenjing Dong ◽  
Dunyan Tan ◽  
Carol C Baskin ◽  
Jerry M Baskin
Keyword(s):  
Seedling Emergence ◽  
Dispersal Ability ◽  
Dormancy Breaking ◽  
Cold Desert ◽  
Standard Procedures ◽  
Emergence Percentage ◽  
Desert Annual ◽  
The Relationship ◽  
Over Time ◽  
Temporal Dispersal

Abstract Many studies have been done on the relationship between variation in morphology, dispersal ability and degree of dormancy of heterocarpic species with dimorphic diaspores. However, there are far fewer such studies on species that produce trimorphic diaspores. Our aim was to compare dormancy and germination of achenes from peripheral, intermediate and central positions in the capitulum of the diaspore-trimorphic cold desert annual Asteraceae species Heteracia szovitsii, an important component of plant communities in the cold deserts of NW China. Dormancy breaking/germination responses of the three achene morphs and of seeds isolated from the pericarp were tested in the laboratory using standard procedures, and seedling emergence phenology of the achene morphs was monitored under natural cold desert temperature conditions in an experimental garden with and without supplemental watering. Depth of dormancy of the three achene morphs was peripheral > intermediate > central. Seedlings from the three morphs emerged in spring and in autumn. Cumulative seedling emergence percentage from achenes during 47 months of burial was central > intermediate > peripheral. Central achene morphs emerged over a period of ~12 months after sowing, while intermediate and peripheral achene morphs did so for ~40 and 47 months, respectively. Thus, H. szovitsii exhibits a temporal dispersal strategy. No viable central or intermediate achene morphs were present after 16 and 40 months, respectively, but ~60 % of the non-emerged peripheral achenes morphs were viable after 47 months. Based on our results on diaspore dormancy and those of a previous study of diaspore spatial dispersal of H. szovitsii, we conclude that this species has a high–intermediate–low risk diaspore dispersal/dormancy strategy that likely increases the chances for population persistence over time and space.

Gradual or pulsed evolution: when should punctuational explanations be preferred?

Paleobiology ◽  
2008 ◽  
Vol 34 (3) ◽  
pp. 360-377 ◽  
Author(s):  
Gene Hunt
Keyword(s):  
Random Walk ◽  
Evolutionary Dynamics ◽  
Evolutionary Model ◽  
Information Criterion ◽  
Evolutionary Change ◽  
Statistical Framework ◽  
Size Evolution ◽  
Uniform Model ◽  
Punctuated Evolution ◽  
Over Time

The problem of gradual versus punctuated change within phyletic lineages can be understood in terms of the homogeneity of evolutionary dynamics. Hypotheses of punctuated change imply that the rules governing evolutionary change shift over time such that the normal dynamics of stasis are temporarily suspended, permitting a period of net evolutionary change. Such explanations are members of a larger class of models in which evolutionary dynamics are in some way heterogeneous over time. In this paper, I develop a likelihood-based statistical framework to evaluate the support for this kind of evolutionary model. This approach divides evolutionary sequences into nonoverlapping segments, each of which is fit to a separate evolutionary model. Models with heterogeneous dynamics are generally more complex—they require more parameters to specify—than uniform evolutionary models such as random walks and stasis. The Akaike Information Criterion can be used to judge whether the greater complexity of punctuational models is offset by a sufficient gain in log-likelihood for these models to be preferred.I use this approach to analyze three case studies for which punctuational explanations have been proposed. In the first, a model of punctuated evolution best accounted for changes in pygidial morphology within a lineage of the trilobiteFlexicalymene, but the uniform model of an unbiased random walk remains a plausible alternative. Body size evolution in the radiolarianPseudocubus vemawas neither purely gradual nor completely pulsed. Instead, the best-supported explanation posited a single, pulsed increase, followed later by a shift to an unbiased random walk. Finally, for the much-analyzed claim of “punctuated gradualism“ in the foraminiferaGloborotalia, the best-supported model implied two periods of stasis separated by a period of elevated but not inherently directional evolution. Although the conclusions supported by these analyses generally refined rather than overturned previous views, the present approach differs from those prior in that all competing interpretations were formalized into explicit statistical models, allowing their relative support to be unambiguously compared.

scholarly journals Reassessment of the radiocesium resuspension flux from contaminated ground surfaces in East Japan

2021 ◽  
Author(s):  
Mizuo Kajino ◽  
Akira Watanabe ◽  
Masahide Ishizuka ◽  
Kazuyuki Kita ◽  
Yuji Zaizen ◽  
...  
Keyword(s):  
Land Surface ◽  
Heavy Traffic ◽  
Inhalation Exposure ◽  
Radioactive Decay ◽  
Ground Surface ◽  
Road Dust ◽  
Bare Soil ◽  
Air Concentration ◽  
Deposition Rates ◽  
Order Of Magnitude

Abstract. Resuspension of 137Cs from the contaminated ground surface to the atmosphere is essential for understanding the environmental behaviors of 137Cs and estimating external and inhalation exposure of residents. Kajino et al. (2016) assessed the 137Cs resuspension flux from bare soil and forest ecosystems in East Japan in 2013 using a numerical simulation constrained by surface air concentration measurements. However, the simulation was found to underestimate the observed deposition amounts by two orders of magnitude. The reason for this underestimation is that the simulation assumed that resuspended 137Cs is carried by submicron aerosols, which have low deposition rates. Based on the observational indications that soil dust and bioaerosols are the major carriers of resuspended 137Cs, a new simulation is performed with higher deposition rates constrained by both surface concentrations and deposition amounts. In the new estimation, the areal total annual resuspension of 137Cs in 2013 is 25.7 TBq, which is equivalent to 0.96 % of the initial deposition (2.68 PBq). Due to the rapid deposition rates, the annual redeposition amount is also large at 10.6 TBq, approximately 40 % of the resuspended 137Cs. The resuspension rate through the atmosphere (0.96 % y−1) seems slow, but it (2.6 × 10−5 d−1) may not be negligibly small compared to the actual decreasing trend of the ambient gamma dose rate obtained in Fukushima Prefecture after the radioactive decay of 137Cs plus 134Cs in 2013 is subtracted (1.0–7.9 × 10−4 d−1): Resuspension can account for 1–10 % of the decreasing rate due to decontamination and natural decay through land surface processes. The current simulation underestimated the 137Cs deposition in Fukushima city in winter by more than an order of magnitude, indicating the presence of additional resuspension sources. The site of Fukushima city is surrounded by major roads. Heavy traffic on wet and muddy roads after snow removal operations could generate superlarge (approximately 100 µm in diameter) road dust or road salt particles, which is not included in the model but might contribute to the observed 137Cs at the site.

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