A Mathematical Model Supporting a Hyperpredation Effect in the Apparent Competition Between Invasive Eastern Cottontail and Native European Hare

AbstractIn this work a mathematical model is built in order to validate on theoretical grounds field study results on a three-species system made of two prey, of which one is native and another one invasive, together with a native predator. Specifically, our results mathematically describe the negative effect on the native European hare after the introduction of the invasive Eastern cottontail, mediated by an increased predation rate by foxes. Two nonexclusive assumptions can be made: an increase in cottontail abundance would lead to a larger fox population, magnifying their predatory impact (“hyperpredation”) on hares; alternatively, cottontails attract foxes in patches where they live, which are also important resting sites for hares and consequently the increased presence of foxes results in a higher predation rates on hares. The model results support hyperpredation of increasing fox populations on native hares.

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Consuming Parasitized Aphids Alters the Life History and Decreases Predation Rate of Aphid Predator

Insects ◽

10.3390/insects11120889 ◽

2020 ◽

Vol 11 (12) ◽

pp. 889

Author(s):

Jian-Feng Liu ◽

Xiu-Qin Wang ◽

Jacqueline R. Beggs ◽

Hou-Ding Ou ◽

Xiao-Fei Yu ◽

...

Keyword(s):

Biological Control ◽

Life Table ◽

Intraguild Predation ◽

Survival Rates ◽

Predation Rate ◽

Parasitoid Species ◽

Negative Effect ◽

Aphidius Gifuensis ◽

Practical Implications ◽

Predation Rates

Intraguild predation interactions have substantial theoretical and practical implications for the dynamics of natural competitor populations used for biological control. Intraguild predation on parasitized aphids not only has a direct, negative effect on the parasitoid species, but it may indirectly influence the predator’s development, survival, reproduction and predation rates. In this study, we used two-sex life table theory, life table parameters and predation rates of Aphidoletes aphidimyza (Rondani) to compare when its populations fed on aphids (Myzus persicae Sulzer) (Hemiptera: Aphididae) that were either unparasitized or parasitized by Aphidius gifuensis (Ashmead) (Hymenoptera: Braconidae). Our results showed that individuals of A. aphidimyza were capable of completing their development and attaining maturity when they fed on parasitized aphids. Although feeding on parasitized aphids did not influence the survival rates of immature A. aphidimyza, it did significantly slow their development and extended their longevity, thereby reducing the fecundity and predation rates of A. aphidimyza. These findings may be pivotal for better understanding the sustained coexistence of predators with parasitoids in the biological control of aphids.

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Validation of mathematical model of electrothermal calculation of DC catenary on the basis of scale model

Vestnik of the Railway Research Institute ◽

10.21780/2223-9731-2018-77-4-222-229 ◽

2018 ◽

Vol 77 (4) ◽

pp. 222-229 ◽

Cited By ~ 1

Author(s):

A. V. Paranin ◽

A. B. Batrashov

Keyword(s):

Mathematical Model ◽

Operating Conditions ◽

Scale Model ◽

Contact Network ◽

Scaled Model ◽

Cross Sectional ◽

Current Collection ◽

Topological Features ◽

Study Results ◽

Real Physical Process

The article compares the results of calculation of the finite element simulation of current and temperature distribution in the scale model of the DC catenary with the data of laboratory tests. Researches were carried on various versions of the structural design of catenary model, reflecting the topological features of the wire connection, characteristic of the DC contact network. The proportions of the cross-sectional area of the scaled model wires are comparable to each other with the corresponding values for real DC catenary. The article deals with the operating conditions of the catenary model in the modes of transit and current collection. When studying the operation of the scale catenary model in the transit mode, the effect of the structural elements on the current distribution and heating of the wires was obtained. Within the framework of the scale model, theoretical assumptions about the current overload of the supporting cable near the middle anchoring have been confirmed. In the current collection mode, the experimental dependences of the current in the transverse wires of the scale model are obtained from the coordinate of the current collection point. Using the model it was experimentally confirmed that in the section of the contact wire with local wear, not only the temperature rise occurs but also the current redistribution due to the smaller cross section. Thus, the current share in other longitudinal wires of the scale model increases and their temperature rises. Scale and mathematical models are constructed with allowance for laboratory clamps and supporting elements that participate in the removal of heat from the investigated wires. Obtained study results of the scale model allow to draw a conclusion about the adequacy of the mathematical model and its correspondence to the real physical process. These conclusions indicate the possibility of applying mathematical model for calculating real catenary, taking into account the uneven contact wear wire and the armature of the contact network.

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Does human influence on coastal grasslands habitats affect predation pressure on snakes?

Biota Neotropica ◽

10.1590/s1676-06032013000100039 ◽

2013 ◽

Vol 13 (1) ◽

pp. 366-370 ◽

Cited By ~ 3

Author(s):

Mauricio Beux dos Santos ◽

Mauro Cesar Lamim Martins de Oliveira ◽

Tatiane Penteado Gonçalves ◽

Francis de Mattos Almeida ◽

Daniel Loebmann ◽

...

Keyword(s):

South America ◽

Interspecific Interactions ◽

Predation Rate ◽

Predation Pressure ◽

Key Factors ◽

Human Influence ◽

Real Effect ◽

The Real ◽

Disturbed Areas ◽

Predation Rates

The loss and modification of habitats by humans have been considered key factors in the decline of diversity of species worldwide. However, the real effect caused by these disturbances on the biota is still poorly understood. The assessment of the changes in the network of interspecific interactions, such as predation rates on the native fauna, can be an important tool to diagnose the functionality of disturbed ecosystems. In this study we evaluate the predation rate on snakes in coastal grasslands in South America under human influence. Predation rate of artificial snakes, unlike that obtained in other studies, was lower in human-altered areas than preserved ones. Our findings may be due to a reduction in the abundance and/or richness of species of native predators in more disturbed areas.

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The possibilities of using group regression in the analysis of the diameter structure development in selection forests of Tara

Glasnik Sumarskog fakulteta ◽

10.2298/gsf0285079m ◽

2002 ◽

pp. 79-89 ◽

Cited By ~ 2

Author(s):

Slobodanka Mitrovic ◽

Stanisa Bankovic

Keyword(s):

Mathematical Model ◽

Future Development ◽

Functional Dependence ◽

Primary Objective ◽

Structure Development ◽

Study Results ◽

The Future ◽

Diameter Structure ◽

Group Regression ◽

Diameter Classes

Based on the presented study results, it can be concluded that the distribution of tree numbers per diameter degrees (diameter structure) in the four measurements of the compartments 51 and 75, did not change. It was also concluded that one functional dependence could be applied for both compartments N=e5,9?e?0,39*d The result of the above is that also in the following measurements, the diameter structure will remain unchanged, in cases of the same or similar selection cuttings both by the scope and by the distribution of felled trees per diameter classes The primary objective of this type of study is to predict, based on a mathematical model of diameter structure development, effect of the scope of selection cuttings and the number of recruitments on the diameter structure, and the simulation of growth, the distribution of trees per diameter classes in the following measurement or measurements, i.e. to foresee the future development of selection stands.

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PHYSIOLOGICAL STATE AND PRODUCTIVITY OF ANIMALS UNDER THERMAL STRESS

VESTNIK OF THE BASHKIR STATE AGRARIAN UNIVERSITY ◽

10.31563/1684-7628-2019-51-3-26-31 ◽

2019 ◽

Vol 51 (3) ◽

pp. 26-31

Author(s):

E.A. Azhmuldinov ◽

◽

Yu.N. Chernyshenko ◽

M.G. Titov ◽

◽

...

Keyword(s):

Hematological Parameters ◽

Physiological State ◽

Live Weight ◽

Blood Parameters ◽

Maximum Temperature ◽

Total Plasma ◽

Ambient Temperatures ◽

Study Results ◽

Total Plasma Protein ◽

Negative Effect

A study was conducted of the effect of heat stress on the clinical and physiological state of male rabbits at the age of 5 months with an average live weight of 1551 g. The maximum temperature the animals were exposed to during the experiment was +42 °C. The study results showed a decrease in feed intake and an increase in water consumption, which contributed to a decrease in live weight. Hematological parameters, including hemoglobin, erythrocytes, leukocytes, total plasma protein, globulins and cholesterol increased during the action of this stress factor. It was found that the effect of high ambient temperatures on rabbits negatively affected their physiological functions; the negative effect was reflected by the morphological and biochemical blood parameters.

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PECULIARITIES OF THE RADIATION PATTERN OF THE BRAIN AND INTERNAL ORGANS OF NEWBORNS WHO UNDERWENT SEVERE PERINATAL ASPHYXIA AND UNDERWENT GENERAL THERAPEUTIC HYPOTHERMIA, ACCORDING TO THE PILOT STUDY RESULTS

PEDIATRIA Journal named after G N SPERANSKY ◽

10.24110/0031-403x-2021-100-1-30-35 ◽

2021 ◽

Vol 100 (1) ◽

pp. 30-35

Author(s):

N.S. Vorotyntseva ◽

◽

V.V. Orlova ◽

A.N. Motina ◽

A.D. Novikova ◽

...

Keyword(s):

Therapeutic Hypothermia ◽

Perinatal Asphyxia ◽

Control Group ◽

Internal Organs ◽

X Ray ◽

Abdominal Organs ◽

Study Results ◽

Negative Effect ◽

Chest X Ray ◽

The Brain

Objective of the research: to study the features of the radiological picture of the brain and internal organs of newborns with severe perinatal asphyxia, who underwent general therapeutic hypothermia (GTH). Materials and methods: the study included 116 newborns with severe perinatal asphyxia. GTH was performed in 72 patients (group 1), 44 children did not receive hypothermia in the 2 (control) group. In the first 6 hours of life, children of groups 1 and 2 underwent ultrasound of the brain and abdominal organs and chest x-ray. The complex ultrasound scan was repeated at 3–5, 7–10, 14–16 and 21–28 days. Repeated chest x-ray was carried out strictly according to the indications. Results: GTH reduced the incidence of organic brain lesions by 18% in children with severe perinatal asphyxia (p0,05). The study revealed a number of undesirable consequences associated with GTH. Transient effusion into the abdominal and thoracic cavities was diagnosed by ultrasound in 8 (11%) patients after hypothermia, while there were no such changes in children in the control group (p<0,05). X-ray of the chest in newborns who received GTH during the first 14 days revealed edematous-hemorrhagic changes in the lungs more often than in patients of the control group – 55 (76%) and 24 (55%), respectively (p<0,05). Conclusions: GTH effectively prevented the development of severe post-hypoxic changes in the brain. The negative effect of hypothermia on microcirculation was manifested by the development of effusion into the serous cavities and edematous-hemorrhagic syndrome.

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Effects of Food Processing on In Vivo Antioxidant and Hepatoprotective Properties of Green Tea Extracts

Antioxidants ◽

10.3390/antiox8120572 ◽

2019 ◽

Vol 8 (12) ◽

pp. 572 ◽

Cited By ~ 2

Author(s):

Xiao-Yu Xu ◽

Jie Zheng ◽

Jin-Ming Meng ◽

Ren-You Gan ◽

Qian-Qian Mao ◽

...

Keyword(s):

Green Tea ◽

Food Processing ◽

Antioxidant Activities ◽

Ultrasound Treatment ◽

Positive Effects ◽

In Vivo Experiments ◽

Study Results ◽

Negative Effect

Food processing can affect the nutrition and safety of foods. A previous study showed that tannase and ultrasound treatment could significantly increase the antioxidant activities of green tea extracts according to in vitro evaluation methods. Since the results from in vitro and in vivo experiments may be inconsistent, the in vivo antioxidant activities of the extracts were studied using a mouse model of alcohol-induced acute liver injury in this study. Results showed that all the extracts decreased the levels of aspartate transaminase and alanine aminotransferase in serum, reduced the levels of malondialdehyde and triacylglycerol in the liver, and increased the levels of catalase and glutathione in the liver, which can alleviate hepatic oxidative injury. In addition, the differences between treated and original extracts were not significant in vivo. In some cases, the food processing can have a negative effect on in vivo antioxidant activities. That is, although tannase and ultrasound treatment can significantly increase the antioxidant activities of green tea extracts in vitro, it cannot improve the in vivo antioxidant activities, which indicates that some food processing might not always have positive effects on products for human benefits.

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Predation of the Buffy-fronted Seedeater Sporophila frontalis (Aves: Emberizidae) on Merostachys neesii (Poaceae: Babusoideae) seeds during a masting event in the Atlantic forest

Biota Neotropica ◽

10.1590/s1676-06032011000300033 ◽

2011 ◽

Vol 11 (3) ◽

pp. 407-411 ◽

Cited By ~ 5

Author(s):

César Cestari ◽

Cláudio João Bernardi

Keyword(s):

Atlantic Forest ◽

Predation Rate ◽

The Other ◽

Southeastern Brazil ◽

Forest Species ◽

Forest Reserve ◽

Point Counts ◽

Other Hand ◽

Predatory Impact

The Buffy-fronted Seedeater Sporophila frontalis (Verreaux, 1869) is frequently found foraging on seeds during ephemeral masting events of bamboos in the Atlantic forest. In the present study, we analyzed the predation activity of S. frontalis on seeds of Merostachys neesii Rupr. during a masting event in an Atlantic forest reserve on southeastern Brazil. We conducted point counts in spots with M. neesii and in spots without bamboos along trails to determine the presence of S. frontalis on M. neesii clumps. Additionally, focal observations on bamboo clumps and seed traps were used to verify the predatory impact of S. frontalis on M. neesii seeds. S. frontalis was present in 6 out 18 point counts in M. neesii clumps. The seedeater behaved territorially in bamboo clumps and presented a mean predation rate of 1.10 bamboo seeds/minute. Seed traps had up to 80% of the seeds predated. The large amount of seeds available during bamboo masting events probably contributes to the maintenance of wandering populations of S. frontalis in the Atlantic forest. On the other hand, the predation of seeds by S. frontalis may reduce the reproductive germination and the propagation of the bamboos whose growth may in turn negatively affect the establishment of other forest species.

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Habitat use of coexisting introduced eastern cottontail and native European hare

Mammalian Biology ◽

10.1016/j.mambio.2013.02.002 ◽

2013 ◽

Vol 78 (4) ◽

pp. 235-240 ◽

Cited By ~ 11

Author(s):

Sandro Bertolino ◽

Nicola Cordero di Montezemolo ◽

Aurelio Perrone

Keyword(s):

Habitat Use ◽

European Hare ◽

Eastern Cottontail

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Launch Bar Dynamics Character Analysis of Carrier-Based Aircraft Catapult Launch

Applied Sciences ◽

10.3390/app9153079 ◽

2019 ◽

Vol 9 (15) ◽

pp. 3079

Author(s):

Zhu ◽

Lu ◽

Yang ◽

Ji ◽

Han ◽

...

Keyword(s):

Mathematical Model ◽

Working Condition ◽

Center Of Gravity ◽

Obvious Effect ◽

Character Analysis ◽

Driving Mechanisms ◽

Study Results ◽

Flight Deck

The launch bar is a unique device of carrier-based aircraft, which is connected to the nose gear and shuttle. In order to avoid the launch bar striking the flight deck after the launch bar pops out of the shuttle, it is very important to research the dynamics performance of the launch bar. This paper establishes a staged mathematical model of catapult launch including the launch bar, a steam-powered catapult, a holdback bar, and a carrier-based aircraft. This article studied the effect of the mass of the launch bar, restoring moment of the launch bar, and center of gravity position of the launch bar on the dynamics performance of the launch bar. The results showed the following: (1) we could reduce the risk collision of the launch bar and deck by reducing the mass of the launch bar, increasing the restoring moment, and shifting the center of gravity position of the launch bar; (2) under the working condition of this article, we changed the center of gravity position of the launch bar to control the sink of the launch bar end, having the most obvious effect, and we reduced the mass of the launch bar, having the least effect on controlling the sink of the launch bar end; however, reducing the mass of the launch bar could also greatly reduce the risk collision of the launch bar and deck; (3) in order to avoid the launch bar striking the flight deck, the restoring moment of the launch bar must overcome the sum of other moments. The study results can give a theoretical reference for designing and testing the launch bars of carrier-based aircraft. It can also give a theoretical reference for designing and testing the launch bar’s driving mechanisms.

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