scholarly journals Development of a species-specific model of cerebral hemodynamics

2005 ◽  
Vol 20 (4) ◽  
pp. 385-386
Author(s):  
S. Daun ◽  
T. Tjardes
Keyword(s):  
Specific Model ◽  
Cerebral Hemodynamics ◽  
Species Specific

scholarly journals Development of a Species-Specific Model of Cerebral Hemodynamics

2005 ◽  
Vol 6 (3) ◽  
pp. 181-195
Author(s):  
Silvia Daun ◽  
Thorsten Tjardes
Keyword(s):  
Blood Pressure ◽  
Mathematical Model ◽  
Cardiac Output ◽  
Head Injuries ◽  
Cerebral Arteries ◽  
Specific Model ◽  
Cerebral Hemodynamics ◽  
Heart Frequency ◽  
Regulation Mechanisms ◽  
Species Specific

In this paper, a mathematical model for the description of cerebral hemodynamics is developed. This model is able to simulate the regulation mechanisms working on the small cerebral arteries and arterioles, and thus to adapt dynamically the blood flow in brain. Special interest is laid on the release of catecholamines and their effect on heart frequency, cardiac output and blood pressure. Therefore, this model is able to describe situations of severe head injuries in a very realistic way.

scholarly journals Relationships between fish and otolith dimensions of Pomatomus saltatrix (Linnaeus, 1766) (Perciformes: Pomatomidae) in southeastern Brazil

2019 ◽  
Vol 17 (1) ◽  
Author(s):  
Geysa M. de Souza ◽  
Rafael de A. Tubino ◽  
Cassiano Monteiro-Neto ◽  
Marcus R. da Costa
Keyword(s):  
Food Habits ◽  
Condition Factor ◽  
Specific Model ◽  
Southeastern Brazil ◽  
Length Frequency ◽  
Pomatomus Saltatrix ◽  
Relative Growth ◽  
Frequency Distributions ◽  
Growth Constants ◽  
Species Specific

ABSTRACT The bluefish, Pomatomus saltatrix (Linnaeus, 1766), was used as a species-specific model to study morphometric relationships between otolith size and relative growth variables. Length-weight relationships between Otolith (Length-OL, Height-OH, and Weight-OW) and fish measurements (Total Length-TL and Total Weight-TW) were determined for fishes captured monthly during the year 2015 off the southeastern coast of Brazil. The ANCOVA and Kruskal-Wallis analysis did not indicate significant differences in the relative growth constants between sexes and length frequency distributions (p > 0.05). The condition factor also did not present significant differences between sexes, and right and left otolith measurements (p > 0.05). A total of 398 specimens were sampled: TL = 43.6-67.0 cm, TW = 365-2400 g, OL = 9.65-15.25 mm, OH = 3.65 - 5.45 mm and OW = 0.03-0.11 g. The LWR for grouped sexes was TW = 0.050TL2.55 and otoliths OW = 6.17E-05OL2.59. The best adjustments were TL vs OL (r2 = 0.90); OL vs OW (r2 = 0.90); TW vs OW (r2 = 0.81); and TW vs OL (r2 = 0.80). These results showed that such relationships are helpful tools for predicting the fish size and weight from otoliths, which may be used in food habits and paleontology studies, and other fisheries management applications.

scholarly journals New 3D measurements of large redwood trees for biomass and structure

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Mathias Disney ◽  
Andrew Burt ◽  
Phil Wilkes ◽  
John Armston ◽  
Laura Duncanson
Keyword(s):  
Laser Scanning ◽  
3D Structure ◽  
Terrestrial Laser Scanning ◽  
Specific Model ◽  
Observation Data ◽  
Ecosystem Structure ◽  
Above Ground Biomass ◽  
Large Trees ◽  
Earth Observation Data ◽  
Species Specific

Abstract Large trees are disproportionately important in terms of their above ground biomass (AGB) and carbon storage, as well as their wider impact on ecosystem structure. They are also very hard to measure and so tend to be underrepresented in measurements and models of AGB. We show the first detailed 3D terrestrial laser scanning (TLS) estimates of the volume and AGB of large coastal redwood Sequoia sempervirens trees from three sites in Northern California, representing some of the highest biomass ecosystems on Earth. Our TLS estimates agree to within 2% AGB with a species-specific model based on detailed manual crown mapping of 3D tree structure. However TLS-derived AGB was more than 30% higher compared to widely-used general (non species-specific) allometries. We derive an allometry from TLS that spans a much greater range of tree size than previous models and so is potentially better-suited for use with new Earth Observation data for these exceptionally high biomass areas. We suggest that where possible, TLS and crown mapping should be used to provide complementary, independent 3D structure measurements of these very large trees.

scholarly journals Course of Infection with the Emergent Pathogen Brucella microti in Immunocompromised Mice

2011 ◽  
Vol 79 (10) ◽  
pp. 3934-3939 ◽  
Author(s):  
María P. Jiménez de Bagüés ◽  
Alba de Martino ◽  
Juan F. Quintana ◽  
Ana Alcaraz ◽  
Julián Pardo
Keyword(s):  
Nk Cell ◽  
Bacterial Load ◽  
Cell Activity ◽  
Specific Model ◽  
Wild Rodents ◽  
Content Type ◽  
Immunodeficient Mice ◽  
Emergent Pathogen ◽  
Immunocompromised Mice ◽  
Species Specific

ABSTRACTA newBrucellaspecies,Brucella microti, has been isolated from wild rodents and found to be pathogenic in mice. The biological relevance of this new mouse pathogen is clear, as it allows us to studyBrucellainfection in a species-specific model. The course of infection in wild-type (wt) and immunodeficient mice that lack B (Jh), T and B (SCID), or T, B, and NK (SCID.Beige) cells was analyzed over 3 weeks. wt mice completely cleared bacteria from the liver and spleen after that time. However, SCID mice showed a much higher bacterial load in the spleen and liver than wt and Jh mice after 1 week and maintained the same level during the next 2 weeks. All mice tested survived for the 3 weeks. In contrast, the bacterial levels in mice that lacked NK cell activity progressively increased and these mice succumbed to infection after 16 to 18 days. Histopathology analysis of infected mice showed extensive areas of necrotic tissue and thrombosis in liver after 1 week in all infected SCID.Beige mice but were not seen in either SCID or wt animals. These processes were dramatically increased after 21 days, corresponding with the death of SCID.Beige animals. Our results indicate that T and/or B cells are required for the control of infection with the mouse pathogenBrucella microtiin liver and spleen but that NK cells are crucial for survival in the absence of B and T cells. In addition, they suggest that controlled granuloma formation is critical to clear this type of infection in wt mice.

scholarly journals Examining the accuracy of trackways for predicting gait selection and speed of locomotion

2020 ◽  
Author(s):  
Andres Marmol-Guijarro ◽  
Robert Nudds ◽  
Lars Folkow ◽  
Jonathan Codd
Keyword(s):  
Stride Length ◽  
Specific Model ◽  
Walking Gait ◽  
Lack Of Information ◽  
Substrate Properties ◽  
Ground Truthing ◽  
Species Specific ◽  
Made In ◽  
Require Information ◽  
Bouncing Gaits

Abstract Background Using Froude numbers (Fr) and relative stride length (stride length: hip height), trackways have been widely used to determine the speed and gait of an animal. This approach, however, is limited by the ability to estimate hip height accurately and by the lack of information related to the substrate properties when the tracks were made, in particular for extinct fauna. By studying the Svalbard ptarmigan moving on snow, we assessed the accuracy of trackway predictions from a species-specific model and two additional Fr based models by ground truthing data extracted from videos as the tracks were being made. Results The species-specific model accounted for more than 60% of the variability in speed for walking and aerial running, but only accounted for 19% when grounded running, likely due to its stabilizing role while moving faster over a changing substrate. The error in speed estimated was 0-35% for all gaits when using the species-specific model, whereas Fr based estimates produced errors up to 55%. The highest errors were associated with the walking gait. The transition between pendular to bouncing gaits fell close to the estimates using relative stride length described for other extant vertebrates. Conversely, the transition from grounded to aerial running appears to be species specific and highly dependent on posture and substrate. Conclusion Altogether, this study highlights that using trackways to derive predictions on the locomotor speed and gait, using stride length as the only predictor, are problematic as accurate predictions require information from the animal in question.

scholarly journals Modeling the Red-shanked Douc (Pygathrix nemaeus) distribution in Vietnam using Maxent

2019 ◽  
Vol 35 (3) ◽  
Author(s):  
Nguyen Tuan Anh ◽  
Le Duc Minh ◽  
Pham Viet Hung ◽  
Vu Thi Duyen
Keyword(s):  
Species Distribution ◽  
Species Distribution Modeling ◽  
Specific Model ◽  
Fine Tuning ◽  
Model Parameters ◽  
The North ◽  
Distribution Modeling ◽  
Pygathrix Nemaeus ◽  
Species Specific ◽  
Occurrence Records

The Red-shanked Douc (Pygathrix nemaeus) is the only douc species recorded in all three countries of Indochina. It is classified as Endangered by IUCN, and is believed to have experienced a major drop of more than 50% of its population over the last 40 years. The known distribution of main P. nemaeus populations in Vietnam ranges from Pu Mat National Park, Nghe An Province in the North to the Kon Ha Nung, Gia Lai Province in the South. In this study, we used Maxent, a species distribution modeling approach that is shown to a have high predictive power even with low number of occurrence records, to predict the current distribution of the Red-shanked Douc in Vietnam based on published records. The results show that P. nemaeus inhabits a region from Nghe An to Kon Tum Province, with areas from Ha Tinh, Quang Binh, Quang Tri, Thua Thien – Hue, Da Nang – Quang Nam Provinces exhibiting the highest potential. With all model parameters already listed here, studies in the future may incorporate more occurrence records to develop better models, or other environmental variables to assess the influence of different factors on the species distribution. The results also suggest that species distribution modeling, coupled with a carefully checked and filtered occurrence dataset, as well as species-specific model fine-tuning and evaluating, can help address many conservation issues in Vietnam.      

scholarly journals Examining the accuracy of trackways for predicting gait selection and speed of locomotion

2020 ◽  
Author(s):  
Andres Marmol-Guijarro ◽  
Robert Nudds ◽  
Lars Folkow ◽  
Jonathan Codd
Keyword(s):  
Stride Length ◽  
Specific Model ◽  
Walking Gait ◽  
Lack Of Information ◽  
Substrate Properties ◽  
Ground Truthing ◽  
Species Specific ◽  
Made In ◽  
Require Information ◽  
Bouncing Gaits

Abstract Background Using Froude numbers (Fr) and relative stride length (stride length: hip height), trackways have been widely used to determine the speed and gait of an animal. This approach, however, is limited by the ability to estimate hip height accurately and by the lack of information related to the substrate properties when the tracks were made, in particular for extinct fauna. By studying the Svalbard ptarmigan moving on snow, we assessed the accuracy of trackway predictions from a species-specific model and two additional Fr based models by ground truthing data extracted from videos as the tracks were being made.Results The species-specific model accounted for more than 60% of the variability in speed for walking and aerial running, but only accounted for 19% when grounded running, likely due to its stabilizing role while moving faster over a changing substrate. The error in speed estimated was 0-35% for all gaits when using the species-specific model, whereas Fr based estimates produced errors up to 55%. The highest errors were associated with the walking gait. The transition between pendular to bouncing gaits fell close to the estimates using relative stride length described for other extant vertebrates. Conversely, the transition from grounded to aerial running appears to be species specific and highly dependent on posture and substrate.Conclusion Altogether, this study highlights that using trackways to derive predictions on the locomotor speed and gait, using stride length as the only predictor, are problematic as accurate predictions require information from the animal in question.

scholarly journals Self-organization of collective escape in pigeon flocks

2022 ◽  
Vol 18 (1) ◽  
pp. e1009772
Author(s):  
Marina Papadopoulou ◽  
Hanno Hildenbrandt ◽  
Daniel W. E. Sankey ◽  
Steven J. Portugal ◽  
Charlotte K. Hemelrijk
Keyword(s):  
Collective Behavior ◽  
Computational Models ◽  
Collective Motion ◽  
Specific Model ◽  
Self Organization ◽  
Behavioral Rules ◽  
Bearing Angle ◽  
Gps Trajectories ◽  
Group Members ◽  
Species Specific

Bird flocks under predation demonstrate complex patterns of collective escape. These patterns may emerge by self-organization from local interactions among group-members. Computational models have been shown to be valuable for identifying what behavioral rules may govern such interactions among individuals during collective motion. However, our knowledge of such rules for collective escape is limited by the lack of quantitative data on bird flocks under predation in the field. In the present study, we analyze the first GPS trajectories of pigeons in airborne flocks attacked by a robotic falcon in order to build a species-specific model of collective escape. We use our model to examine a recently identified distance-dependent pattern of collective behavior: the closer the prey is to the predator, the higher the frequency with which flock members turn away from it. We first extract from the empirical data of pigeon flocks the characteristics of their shape and internal structure (bearing angle and distance to nearest neighbors). Combining these with information on their coordination from the literature, we build an agent-based model adjusted to pigeons’ collective escape. We show that the pattern of turning away from the predator with increased frequency when the predator is closer arises without prey prioritizing escape when the predator is near. Instead, it emerges through self-organization from a behavioral rule to avoid the predator independently of their distance to it. During this self-organization process, we show how flock members increase their consensus over which direction to escape and turn collectively as the predator gets closer. Our results suggest that coordination among flock members, combined with simple escape rules, reduces the cognitive costs of tracking the predator while flocking. Such escape rules that are independent of the distance to the predator can now be investigated in other species. Our study showcases the important role of computational models in the interpretation of empirical findings of collective behavior.

scholarly journals Parameterizing and operationalizing zooplankton population dynamic and trophic interaction models

2014 ◽  
Vol 71 (2) ◽  
pp. 234-235
Author(s):  
Stéphane Plourde ◽  
Howard I. Browman
Keyword(s):  
Population Dynamic ◽  
Simulation Models ◽  
Specific Model ◽  
Trophic Interaction ◽  
Interaction Models ◽  
Research Fields ◽  
Physiological Processes ◽  
Model Parameterization ◽  
Zooplankton Population ◽  
Species Specific

Abstract Plourde, S., and Browman, H. I. 2014. Parameterizing and operationalizing zooplankton population dynamic and trophic interaction models. – ICES Journal of Marine Science, 71: 234–235. This themed set (TS) of articles was motivated by the need for modellers and biologists–ecologists to work more closely together to produce more realistic simulation models of zooplankton population dynamics and trophic interactions. The TS was intended to cover a broad range of subjects and potential approaches, including identifying crucial gaps in our knowledge and parameterization of biological/physiological processes, experimental/fieldwork aimed at quantifying the response of key physiological and behavioural processes to variations in the environment, identifying novel modelling approaches that would enable the development of simulation models that would minimize the need for species-specific (and stage-specific) model parameterization, etc. Five articles were accepted for inclusion in the TS. They cover the majority of these themes. TSs are intended to be instrumental in focusing attention, triggering opinions, and stimulating ideas, discussion and activity in specific research fields. We hope that this TS has achieved that.

scholarly journals Self-organization of collective escape in pigeon flocks

2021 ◽  
Author(s):  
Marina Papadopoulou ◽  
Hanno Hildenbrandt ◽  
Daniel W.E. Sankey ◽  
Steven J. Portugal ◽  
Charlotte K. Hemelrijk
Keyword(s):  
Collective Behavior ◽  
Computational Models ◽  
Collective Motion ◽  
Specific Model ◽  
Self Organization ◽  
Predator Prey ◽  
Behavioral Rules ◽  
Bearing Angle ◽  
Species Specific

Bird flocks under predation demonstrate complex patterns of collective escape. These patterns may emerge by self-organization from simple interactions among group-members. Computational models have been shown to be valuable for identifying the behavioral rules that may govern these interactions among individuals during collective motion. However, our knowledge of such rules for collective escape is limited by the lack of quantitative data on bird flocks under predation in the field. In the present study, we analyze the first dataset of GPS trajectories of pigeons in airborne flocks attacked by a robotic falcon in order to build a species-specific model of collective escape. We use our model to examine a recently identified distance-dependent pattern of collective behavior that shows an increase in the escape frequency of pigeons when the predator is closer. We first extract from the empirical data the characteristics of pigeon flocks regarding their shape and internal structure (bearing angle and distance to nearest neighbours). Combining these with information on their coordination from the literature, we build an agent-based model tuned to pigeons' collective escape. We show that the pattern of increased escape frequency closer to the predator arises without flock-members prioritizing escape when the predator is near. Instead, it emerges through self-organization from an individual rule of predator-avoidance that is independent of predator-prey distance. During this self-organization process, we uncover a role of hysteresis and show that flock members increase their consensus over the escape direction and turn collectively as the predator gets closer. Our results suggest that coordination among flock-members, combined with simple escape rules, reduces the cognitive costs of tracking the predator. Such rules that are independent of predator-prey distance can now be examined in other species. Finally, we emphasize on the important role of computational models in the interpretation of empirical findings of collective behavior.

Sign in / Sign up

Export Citation Format

Share Document