A General Multivariate Dose–Response Model

1986 ◽  
Vol 43 (9) ◽  
pp. 1684-1693 ◽  
Author(s):  
J. Schnute ◽  
J. O. T. Jensen
Keyword(s):  
Environmental Factors ◽  
General Model ◽  
Arbitrary Number ◽  
Biological Response ◽  
Critical Factor ◽  
Companion Paper ◽  
Community Response ◽  
Relative Importance ◽  
Response Model ◽  
Number Of Factors

This paper presents a general model for describing and predicting biological response to environmental factors. The theory embraces concepts and models used in earlier studies of the effects of toxicity on fish, and it extends these ideas in several directions. It can include an arbitrary number of factors, either detrimental or beneficial to the organism. Also, its statistical formulation allows (1) hypothesis testing to determine the relative importance of various factors and (2) calculation of critical factor levels that (with prescribed confidence) assure a community response no worse than a specified level. Our model is based on earlier work by Schnute and McKinnell, and, like theirs, its parameters have biologically meaningful interpretations. Our discussion includes an explanation of how the model relates specifically to toxicity studies. In a companion paper (Can. J. Fish. Aquat. Sci. 43: 1694–1709), we use our model to investigate salmonid response to gas supersaturation and ancillary factors.

scholarly journals Epigenetic Approach to PTSD: In the Aspects of Rat Models

2021 ◽  
Author(s):  
Asli Aykac ◽  
Rasime Kalkan
Keyword(s):  
Risk Factors ◽  
Environmental Factors ◽  
Animal Studies ◽  
Stress Disorder ◽  
Biological Response ◽  
Traumatic Experiences ◽  
Biochemical Processes ◽  
Life Threatening ◽  
Shed Light

AbstractPosttraumatic stress disorder (PTSD) is a stress-related mental disorder and develops after exposure to life-threatening traumatic experiences. The risk factors of PTSD included genetic factors; alterations in hypothalamic–pituitary–adrenal (HPA) axis; neurotrophic, serotonergic, dopaminergic, and catecholaminergic systems; and a variety of environmental factors, such as war, accident, natural disaster, pandemic, physical, or sexual abuse, that cause stress or trauma in individuals. To be able to understand the molecular background of PTSD, rodent animal models are widely used by researchers. When looking for a solution for PTSD, it is important to consider preexisting genetic risk factors and physiological, molecular, and biochemical processes caused by trauma that may cause susceptibility to this disorder. In studies, it is reported that epigenetic mechanisms play important roles in the biological response affected by environmental factors, as well as the task of programming cell identity. In this article, we provided an overview of the role of epigenetic modifications in understanding the biology of PTSD. We also summarized the data from animal studies and their importance during the investigation of PTSD. This study shed light on the epigenetic background of stress and PTSD.

City Children’s Nature Knowledge and Contact: It Is Not Just About Biodiversity Provision

2017 ◽  
Vol 50 (10) ◽  
pp. 1145-1171 ◽  
Author(s):  
Claire Freeman ◽  
Aviva Stein ◽  
Kathryn Hand ◽  
Yolanda van Heezik
Keyword(s):  
New Zealand ◽  
Environmental Factors ◽  
Ethnic Group ◽  
Social Factors ◽  
Green Spaces ◽  
Social Connections ◽  
Relative Importance ◽  
Linear Modeling ◽  
Generalized Linear Modeling ◽  
Nature Contact

Much attention has been directed at the perceived decline in city children’s contact with nature. We used a child-centric approach to assess neighborhood nature knowledge in 187 children aged 9 to 11 years, from different socioeconomic and ethnic groups in three New Zealand cities. We evaluated the relative importance of social (independence, gender, social connections, deprivation, age) and environmental factors (biodiversity) in explaining variation in knowledge at a scale relevant to each child’s independent movements. Our biodiversity evaluation reflected the natural dimensions of the habitats where children interacted with nature. Generalized linear modeling identified ethnicity as having the strongest association with nature knowledge. Within each ethnic group, social factors were most important (independence, social connections, deprivation) except for Pākehā/NZ European children, where local biodiversity was most important. Enhancing biodiversity values of private green spaces (yards) would be effective in facilitating opportunities to experience nature, which is fundamental to supporting nature contact.

scholarly journals Environmental Factors Modulating Antibiotic and Siderophore Biosynthesis by Pseudomonas fluorescensBiocontrol Strains

1999 ◽  
Vol 65 (6) ◽  
pp. 2429-2438 ◽  
Author(s):  
Brion K. Duffy ◽  
Geneviève Défago
Keyword(s):  
Salicylic Acid ◽  
Environmental Factors ◽  
Yeast Extract ◽  
Carbon Sources ◽  
Nutrient Broth ◽  
General Effect ◽  
Antimicrobial Compounds ◽  
Fermentation Time ◽  
Number Of Factors ◽  
Strain Dependent

ABSTRACT Understanding the environmental factors that regulate the biosynthesis of antimicrobial compounds by disease-suppressive strains of Pseudomonas fluorescens is an essential step toward improving the level and reliability of their biocontrol activity. We used liquid culture assays to identify several minerals and carbon sources which had a differential influence on the production of the antibiotics 2,4-diacetylphloroglucinol (PHL), pyoluteorin (PLT), and pyrrolnitrin and the siderophores salicylic acid and pyochelin by the model strain CHA0, which was isolated from a natural disease-suppressive soil in Switzerland. Production of PHL was stimulated by Zn2+, NH4Mo2+, and glucose; the precursor compound mono-acetylphloroglucinol was stimulated by the same factors as PHL. Production of PLT was stimulated by Zn2+, Co2+, and glycerol but was repressed by glucose. Pyrrolnitrin production was increased by fructose, mannitol, and a mixture of Zn2+ and NH4Mo2+. Pyochelin production was increased by Co2+, fructose, mannitol, and glucose. Interestingly, production of its precursor salicylic acid was increased by different factors, i.e., NH4Mo2+, glycerol, and glucose. The mixture of Zn2+ and NH4Mo2+with fructose, mannitol, or glycerol further enhanced the production of PHL and PLT compared with either the minerals or the carbon sources used alone, but it did not improve siderophore production. Extending fermentation time from 2 to 5 days increased the accumulation of PLT, pyrrolnitrin, and pyochelin but not of PHL. When findings with CHA0 were extended to an ecologically and genetically diverse collection of 41 P. fluorescens biocontrol strains, the effect of certain factors was strain dependent, while others had a general effect. Stimulation of PHL by Zn2+ and glucose was strain dependent, whereas PLT production by all strains that can produce this compound was stimulated by Zn2+ and transiently repressed by glucose. Inorganic phosphate reduced PHL production by CHA0 and seven other strains tested but to various degrees. Production of PLT but not pyrrolnitrin by CHA0 was also reduced by 100 mM phosphate. The use of 1/10-strength nutrient broth-yeast extract, compared with standard nutrient broth-yeast extract, amended with glucose and/or glycerol resulted in dramatically increased accumulations of PHL (but not PLT), pyochelin, and salicylic acid, indicating that the ratio of carbon source to nutrient concentration played a key role in the metabolic flow. The results of this study (i) provide insight into the biosynthetic regulation of antimicrobial compounds, (ii) limit the number of factors for intensive study in situ, and (iii) indicate factors that can be manipulated to improve bacterial inoculants.

scholarly journals Effectiveness of the Early Response to COVID-19: Data Analysis and Modelling

Systems ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 21 ◽  
Author(s):  
Edoardo Bertone ◽  
Martin Jason Luna Juncal ◽  
Rafaela Keiko Prado Umeno ◽  
Douglas Alves Peixoto ◽  
Khoi Nguyen ◽  
...  
Keyword(s):  
Network Models ◽  
High Volume ◽  
Early Response ◽  
Model Potential ◽  
Study Data ◽  
Community Response ◽  
Relative Importance ◽  
The World ◽  
Online Sources ◽  
Bayesian Network Models

Governments around the world have introduced a number of stringent policies to try to contain COVID-19 outbreaks, but the relative importance of such measures, in comparison to the community response to these restrictions, the amount of testing conducted, and the interconnections between them, is not well understood yet. In this study, data were collected from numerous online sources, pre-processed and analysed, and a number of Bayesian Network models were developed, in an attempt to unpack such complexity. Results show that early, high-volume testing was the most crucial factor in successfully monitoring and controlling the outbreaks; when testing was low, early government and community responses were found to be both critical in predicting how rapidly cases and deaths grew in the first weeks of the outbreak. Results also highlight that in countries with low early test numbers, the undiagnosed cases could have been up to five times higher than the officially diagnosed cases. The conducted analysis and developed models can be refined in the future with more data and variables, to understand/model potential second waves of contagions.

scholarly journals Structuring of Dragonfly Communities (Insecta: Odonata) in Eastern Amazon: Effects of Environmental and Spatial Factors in Preserved and Altered Streams

Insects ◽  
2019 ◽  
Vol 10 (10) ◽  
pp. 322 ◽  
Author(s):  
Oliveira-Junior ◽  
Juen
Keyword(s):  
Environmental Factors ◽  
Biotic Interactions ◽  
Environmental Variation ◽  
Relative Importance ◽  
Spatial Variables ◽  
Spatial Factors ◽  
The Past ◽  
Analytical Perspective ◽  
Physical Features ◽  
Natural Communities

The evaluation of the effects of environmental factors on natural communities has been one of the principal approaches in ecology; although, over the past decade, increasing importance has been given to spatial factors. In this context, we evaluated the relative importance of environmental and spatial factors for the structuring of the local odonate communities in preserved and altered streams. Adult Odonata were sampled in 98 streams in eastern Amazonia, Brazil. The physical features of each stream were evaluated and spatial variables were generated. Only environmental factors accounted for the variation in the Odonata community. The same pattern was observed in the suborder Zygoptera. For Anisoptera, environmental factors alone affect the variation in the community, considering all the environments together, and the altered areas on their own. As the two Odonata suborders presented distinct responses to environmental factors, this partitioning may contribute to an improvement in the precision of studies in biomonitoring. We thus suggest that studies would have a greater explanatory potential if additional variables are included, related to biotic interactions (e.g., competition). This will require further investigation on a finer scale of environmental variation to determine how the Odonata fauna of Amazonian streams behaves under this analytical perspective.

scholarly journals The theory of metallic corrosion in the light of quantitative measurements

1927 ◽  
Vol 116 (774) ◽  
pp. 425-467 ◽  
Keyword(s):  
Relative Importance ◽  
Improved Method ◽  
Salt Solutions ◽  
Present Communication ◽  
Technical Problems ◽  
The Third ◽  
Quantitative Measurements ◽  
Number Of Factors ◽  
Metallic Corrosion

The principal object of the present research is the discovery of a satisfactory way of measuring the corrosion of metals in water and dilute salt solutions, and the use of it to test the adequacy of the newer electrochemical theory of corrosion as applied to such media. The theory suggests that a large number of factors can influence the rate of corrosion, but does not indicate quantita­tively their relative importance in given conditions, in fact, the theory is based at present upon qualitative or only roughly quantitative measurements. It is desirable, therefore, that a determined attempt should be made to place it upon a sounder basis, on account, both of the inherent interest of the theory and of its importance in technical problems of steadily increasing insistence. The present communication is the first portion of an extensive research; it is divided into three sections, the first gives an outline of the theory as understood by the authors; the second, a brief review of the kind of measurement upon which it rests; the third an improved method of measuring corrosion as applied to the metal zinc, together with an interpretation of the results so far obtained.

Spatial Scale or Amplitude of Predictors as Determinants of the Relative Importance of Environmental Factors to Plant Community Structure

Biotropica ◽  
2012 ◽  
Vol 45 (3) ◽  
pp. 299-307 ◽  
Author(s):  
Marcelo P. Pansonato ◽  
Flávia R. C. Costa ◽  
Carolina V. de Castilho ◽  
Fernanda A. Carvalho ◽  
Gabriela Zuquim
Keyword(s):  
Community Structure ◽  
Environmental Factors ◽  
Spatial Scale ◽  
Plant Community ◽  
Plant Community Structure ◽  
Relative Importance

Anytime Reactive Planning with Decision Automation

2015 ◽  
Vol 1117 ◽  
pp. 245-248
Author(s):  
István Komlósi
Keyword(s):  
Path Planning ◽  
Decision Theory ◽  
Mobile Robots ◽  
Real Time ◽  
Arbitrary Number ◽  
Planning Process ◽  
Relative Importance ◽  
Neural Structure ◽  
Reactive Planning ◽  
Robotic Applications

In many outdoor robotic applications several factors have to be taken into account during a path planning process. In different situations the importance of these factors vary. This paper presents a path planning method for mobile robots that incorporates decision theory to guide the search. A neural structure is proposed to determine the relative importance of the objectives that makes the robot capable of planning in unfamiliar situations. The method is able to handle an arbitrary number of objectives simultaneously and also enables the incorporation of human logic into the planning process. All parts of the algorithm suit real-time implementation.

Sign in / Sign up

Export Citation Format

Share Document