scholarly journals An improved demand curve for analysis of food or drug consumption in animal experiments

2019 ◽  
Author(s):  
Mark Newman ◽  
Carrie R. Ferrario
Keyword(s):  
Demand Curve ◽  
Animal Experiments ◽  
Maximum Response ◽  
Mathematical Framework ◽  
Mathematical Form ◽  
Self Administration ◽  
Demand Curves ◽  
Consumption Data ◽  
Wide Range ◽  
Experimental Protocols

AbstractThe incorporation of microeconomics concepts into studies using preclinincal self-administration procedures has provided critical insights into the factors that influence consumption of a wide range of food and drug reinforcers. In particular, the fitting of demand curves to consumption data provides a powerful analytic tool for computing objective metrics of behavior that can be compared across a wide range of reward types and experimental settings. The results of these analyses depend crucially on the mathematical form used to fit the data. The most common choice is an exponential form proposed by Hursh and Silberberg, which is widely used and has provided fundamental insights into relationships between cost and consumption, but it also has some disadvantages. In this paper we first briefly review the use of demand curves to quantify the motivating effects of food and drugs, then we describe the current methodology and highlight some potential issues that arise in its application. To address these issues, we propose a new mathematical framework for the analysis of consumption data, including a new functional form for the demand curve. We show that this proposed form gives good fits to data on a range of reinforcers across different animals and different experimental protocols, while allowing for straightforward calculation of key metrics of demand, including preferred consumption level, maximum response, price at maximum response, and price elasticity of demand. We provide software implementing our entire analysis pipeline, including data fits, data visualization, and the calculation of demand metrics.

Animal Experiments and their Alternatives in Psychiatry

1988 ◽  
Vol 15 (4) ◽  
pp. 313-318
Author(s):  
Anthony Stevens
Keyword(s):  
Animal Models ◽  
Human Study ◽  
Animal Experiments ◽  
Experimental Production ◽  
Potential Utility ◽  
Pharmacological Agents ◽  
Wide Range ◽  
Influential Paper ◽  
Adequate Data ◽  
Human Primate

During the last twenty years, the most enthusiastic advocates of the use of animal models in the study of human psychiatric dysfunction have been Harlow and Suomi. In an influential paper, Induced Depression in Monkeys (1974), they argued that more extensive use of non-human primates “would have great potential utility since many manipulations and measurements presently prohibited in human study by ethical and practical considerations could be readily performed on non-human primate subjects in well-controlled experimental environments.” Harlow & Suomi concluded this paper with the following statement: “The results obtained to date on induced depression in monkeys show that proper and profound depressions can be produced relatively easily by a variety of techniques. These induced depressions either bear a close resemblance to human depression or have such similarity as to suggest that closely correlated human and animal depressive patterns may be achieved with refined techniques. The results to date also provide adequate data for the conduct of meaningful researches on the effects of pharmacological agents which either enhance, inhibit or preclude the experimental production of depression. Further, the existence of firm and fast monkey depression syndromes offers vast opportunities for testing a wide range of therapeutic techniques, either behavioural or biochemical.”

GIFFEN EFFECT MODEL

2020 ◽  
Vol 10 (7) ◽  
pp. 1228-1245
Author(s):  
V.I. Tsurikov ◽  
Keyword(s):  
Consumer Choice ◽  
Demand Curve ◽  
Aggregate Demand ◽  
Negative Slope ◽  
Individual Values ◽  
Effect Model ◽  
Demand Curves ◽  
Income Individual ◽  
The Mathematical Model

The mathematical model of the Giffen effect proposed in the article clearly demonstrates both the effect itself and the reasons for its manifestation. The main advantages of the model include its extreme simplicity, which opens up access to the widest circle of readers, the use of standard methods for solving the consumer choice problem, and the most important fundamental agreement with the results of the field experiment of Jensen and Miller. The model shows that any good for which there is a more expensive substitute can be of little value. This or that good is endowed with the appropriate property by a particular consumer due to his or her own preferences, income level and prevailing prices. Any good of little value, including those that can only be consumed by a high-income individual, may turn out to be Giffen’s goods. Therefore, the consumption of Giffen’s product cannot be considered as evidence of the low standard of living of the consumer. According to the model, an increase in demand for an increasingly expensive low-value good, which is the essence of the Giffen paradox, is the result of optimizing a set of goods, i.e. the result of rational consumer behavior. It is shown that for the manifestation of the Giffen effect, it is necessary that the amount of funds allocated by the consumer for the purchase of a low-value good and its more expensive substitute falls into a certain rather narrow range of values. The failures of numerous and long-term studies aimed at detecting empirical manifestations of Giffen behavior in various historical events are explained by the fact that the corresponding analysis was carried out on the basis of averaged rather than individual values of demand for all categories of consumers. As a result, the negative slope of the aggregate demand curve turned out to be dominant over the positive sections of certain individual demand curves.

scholarly journals Sesquiterpene emissions from vegetation: a review

2008 ◽  
Vol 5 (3) ◽  
pp. 761-777 ◽  
Author(s):  
T. R. Duhl ◽  
D. Helmig ◽  
A. Guenther
Keyword(s):  
Plant Species ◽  
Emission Rates ◽  
Sample Collection ◽  
Ambient Temperatures ◽  
Relative Contribution ◽  
Environmental Controls ◽  
Weather Events ◽  
Wide Range ◽  
Experimental Protocols ◽  
Selection Of Species

Abstract. This literature review summarizes the environmental controls governing biogenic sesquiterpene (SQT) emissions and presents a compendium of numerous SQT-emitting plant species as well as the quantities and ratios of SQT species they have been observed to emit. The results of many enclosure-based studies indicate that temporal SQT emission variations appear to be dominated mainly by ambient temperatures although other factors contribute (e.g., seasonal variations). This implies that SQT emissions have increased significance at certain times of the year, especially in late spring to mid-summer. The strong temperature dependency of SQT emissions also creates the distinct possibility of increasing SQT emissions in a warmer climate. Disturbances to vegetation (from herbivores and possibly violent weather events) are clearly also important in controlling short-term SQT emissions bursts, though the relative contribution of disturbance-induced emissions is not known. Based on the biogenic SQT emissions studies reviewed here, SQT emission rates among numerous species have been observed to cover a wide range of values, and exhibit substantial variability between individuals and across species, as well as at different environmental and phenological states. These emission rates span several orders of magnitude (10s–1000s of ng gDW-1 h−1). Many of the higher rates were reported by early SQT studies, which may have included artificially-elevated SQT emission rates due to higher-than-ambient enclosure temperatures and disturbances to enclosed vegetation prior to and during sample collection. When predicting landscape-level SQT fluxes, modelers must consider the numerous sources of variability driving observed SQT emissions. Characterizations of landscape and global SQT fluxes are highly uncertain given differences and uncertainties in experimental protocols and measurements, the high variability in observed emission rates from different species, the selection of species that have been studied so far, and ambiguities regarding controls over emissions. This underscores the need for standardized experimental protocols, better characterization of disturbance-induced emissions, screening of dominant plant species, and the collection of multiple replicates from several individuals within a given species or genus as well as a better understanding of seasonal dependencies of SQT emissions in order to improve the representation of SQT emission rates.

scholarly journals Detection of Mesoscale Seasonal and Interannual Variation in the Vegetation of the Amazon Basin

2005 ◽  
Vol 9 (25) ◽  
pp. 1-16
Author(s):  
Miles G. Logsdon ◽  
Robin Weeks ◽  
Milton Smith ◽  
Jeffery E. Richey ◽  
Victoria Ballester ◽  
...  
Keyword(s):  
Time Series ◽  
El Niño ◽  
Amazon Basin ◽  
El Nino ◽  
Southern Oscillation ◽  
Mathematical Framework ◽  
Spectral Change ◽  
Range Analysis ◽  
Local Variance ◽  
Wide Range

Abstract In the Amazon basin, seasonal and interannual spectral changes measured by satellites result from anthropogenic disturbance and from the interaction between climate variation and the surface cover. Measurements of spectral change, and the characterization of that change, provide information concerning the physical processes evident at this mesoscale. A 17-yr sequence of daily Advanced Very High Resolution Radiometer (AVHRR) global area coverage (GAC) images were analyzed to produce a monthly record of surface spectral change encompassing El Niño–Southern Oscillation (ENSO) cycles. Monthly cloud-free composite images from daily AVHRR data were produced by linear filters that minimized the finescale spatial variance and allowed for a wide range analysis within a consistent mathematical framework. Here the use of a minimized local variance (MLV) filter that produced spatially smooth images in which major land-cover boundaries and spatial gradients are clearly represented is discussed. Changes in the configuration of these boundaries and the composition of the landscape elements they defined are described in terms of quantitative changes in landscape pattern. The time series produced with the MLV filter revealed a marked seasonal difference in the pattern of the landscape and structural differences over the length of the time series. Strikingly, the response of the region to drier El Niño years appears to be delayed in the MLV series, the maximum response being in the year following El Niño with little or no change seen during El Niño.

scholarly journals Differential equation methods for simulation of GFP kinetics in non–steady state experiments

2018 ◽  
Vol 29 (6) ◽  
pp. 763-771 ◽  
Author(s):  
Robert D. Phair
Keyword(s):  
Differential Equation ◽  
Steady State ◽  
Fluorescence Microscopy ◽  
Cell Biology ◽  
Fluorescent Proteins ◽  
Quantitative Information ◽  
Tracer Kinetics ◽  
Mathematical Framework ◽  
Experimental Protocols ◽  
Tracer Kinetic

Genetically encoded fluorescent proteins, combined with fluorescence microscopy, are widely used in cell biology to collect kinetic data on intracellular trafficking. Methods for extraction of quantitative information from these data are based on the mathematics of diffusion and tracer kinetics. Current methods, although useful and powerful, depend on the assumption that the cellular system being studied is in a steady state, that is, the assumption that all the molecular concentrations and fluxes are constant for the duration of the experiment. Here, we derive new tracer kinetic analytical methods for non–steady state biological systems by constructing mechanistic nonlinear differential equation models of the underlying cell biological processes and linking them to a separate set of differential equations governing the kinetics of the fluorescent tracer. Linking the two sets of equations is based on a new application of the fundamental tracer principle of indistinguishability and, unlike current methods, supports correct dependence of tracer kinetics on cellular dynamics. This approach thus provides a general mathematical framework for applications of GFP fluorescence microscopy (including photobleaching [FRAP, FLIP] and photoactivation to frequently encountered experimental protocols involving physiological or pharmacological perturbations (e.g., growth factors, neurotransmitters, acute knockouts, inhibitors, hormones, cytokines, and metabolites) that initiate mechanistically informative intracellular transients. When a new steady state is achieved, these methods automatically reduce to classical steady state tracer kinetic analysis.

scholarly journals From Unpleasant to Unbearable—Why and How to Implement an Upper Limit to Pain And Other Forms of Suffering in Research with Animals

ILAR Journal ◽  
2020 ◽  
Author(s):  
I Anna S Olsson ◽  
Christine J Nicol ◽  
Steven M Niemi ◽  
Peter Sandøe
Keyword(s):  
Animal Experiments ◽  
The European Union ◽  
Animal Suffering ◽  
Social Functions ◽  
In Vivo Assays ◽  
Negative State ◽  
Wide Range ◽  
Potential Benefits ◽  
Degree Of Control

Abstract The focus of this paper is the requirement that the use of live animals in experiments and in vivo assays should never be allowed if those uses involve severe suffering. This requirement was first implemented in Danish legislation, was later adopted by the European Union, and has had limited uptake in North America. Animal suffering can arise from exposure to a wide range of different external and internal events that threaten biological or social functions, while the severity of suffering may be influenced by the animals’ perceptions of their own situation and the degree of control they are able to exert. Severe suffering is more than an incremental increase in negative state(s) but involves a qualitative shift whereby the normal mechanisms to contain or keep negative states at arm’s length no longer function. The result of severe suffering will be a loss of the ability of cope. The idea of putting a cap on severe suffering may be justified from multiple ethical perspectives. In most, if not all, cases it is possible to avoid imposing severe suffering on animals during experiments without giving up the potential benefits of finding new ways to cure, prevent, or alleviate serious human diseases and generate other important knowledge. From this it follows that there is a strong ethical case to favor a regulatory ban on animal experiments involving severe suffering.

scholarly journals EVOLUTION OF THE PRODUCTION AND PRICE OF FOREST BIOMASS FOR ENERGY

FLORESTA ◽  
2018 ◽  
Vol 49 (1) ◽  
pp. 011
Author(s):  
Thiago Manoel Sozinho ◽  
David Alexandre Buratto ◽  
Anadalvo Juazeiro Dos Santos ◽  
João Carlos Garzel Leodoro da Silva ◽  
José Roberto Frega
Keyword(s):  
Energy Production ◽  
Demand Curve ◽  
Supply And Demand ◽  
Forest Biomass ◽  
The State ◽  
Planted Forests ◽  
Native Forests ◽  
Demand Curves ◽  
The Right ◽  
Biomass For Energy

This study aimed to analyze the evolution of the production and price of biomass from native and planted forests of the state of Paraná (Brazil), between 1998 and 2015, based on the behavior of the prices of the products, according to variations of their supply or demand. The annual rates for growth of the price and quantity produced were calculated and related to the displacements of the supply and demand curves of the products. The results indicated a decrease in the quantity and an increase in the biomass price for native forests, which caused a shift in the supply curve to the left. For the biomass of planted forests, the demand curve shifted to the right due to the demand increase of this product for energy production. The behavior of both curves indicated a substitution of the biomass from native forests to biomass from planted forests due to factors related to the increase of environmental protection regarding the native forests located in the state of Paraná

The Characteristic Function, a Method-Specific Alternative to the Horwitz Function

2012 ◽  
Vol 95 (6) ◽  
pp. 1803-1806 ◽  
Author(s):  
Michael Thompson
Keyword(s):  
Detection Limit ◽  
Characteristic Function ◽  
Characteristic Functions ◽  
Mathematical Form ◽  
Essential Difference ◽  
Food Sector ◽  
Wide Range ◽  
Specific Alternative ◽  
Additional Role

Abstract The Horwitz function is compared with the characteristic function as a descriptor of the precision of individual analytical methods. The Horwitz function describes the trend of reproducibility SDs observed in collaborative trials in the food sector over a wide range of concentrations of the analyte. However, it is imperfectly adaptable for describing the precision of individual methods, which is the role of the characteristic function. An essential difference between the two functions is that the characteristic function can accommodate a detection limit. This makes it a useful alternative when the precision of a method down to a detection limit is of interest. Many characteristic functions have a simple mathematical form, the parameters of which can be estimated with the usual resources. The Horwitz function serves an additional role as a fitness-for-purpose criterion in the form of the Horwitz ratio (HorRat). This use also has some shortcomings. The functional form of the characteristic function (with suitable prescribed parameters) is better adapted to this task.

scholarly journals Two decades of research with the GreenLab model in agronomy

2020 ◽  
Author(s):  
Philippe de Reffye ◽  
Baogang Hu ◽  
Mengzhen Kang ◽  
Véronique Letort ◽  
Marc Jaeger
Keyword(s):  
Research Effort ◽  
Mathematical Formulation ◽  
Research Work ◽  
Current Status ◽  
Individual Plant ◽  
Mathematical Framework ◽  
Plant Structure ◽  
Experimental Protocols ◽  
The Individual

Abstract Background With up to 200 published contributions, the GreenLab mathematical model of plant growth, developed since 2000 under Sino-French co-operation for agronomic applications, is descended from the structural models developed in the AMAP unit that characterize the development of plants and encompass them in a conceptual mathematical framework. The model also incorporates widely recognized crop model concepts (thermal time, light use efficiency and light interception), adapting them to the level of the individual plant. Scope Such long-term research work calls for an overview at some point. That is the objective of this review paper, which retraces the main history of the model’s development and its current status, highlighting three aspects. (1) What are the key features of the GreenLab model? (2) How can the model be a guide for defining relevant measurement strategies and experimental protocols? (3) What kind of applications can such a model address? This last question is answered using case studies as illustrations, and through the Discussion. Conclusions The results obtained over several decades illustrate a key feature of the GreenLab model: owing to its concise mathematical formulation based on the factorization of plant structure, it comes along with dedicated methods and experimental protocols for its parameter estimation, in the deterministic or stochastic cases, at single-plant or population levels. Besides providing a reliable statistical framework, this intense and long-term research effort has provided new insights into the internal trophic regulations of many plant species and new guidelines for genetic improvement or optimization of crop systems.

Exchange of multiple indicators across renal-like epithelia: a modeling study of six physiological regimes

1986 ◽  
Vol 251 (6) ◽  
pp. F1073-F1089
Author(s):  
C. J. Lumsden ◽  
M. Silverman
Keyword(s):  
Epithelial Transport ◽  
Transport Processes ◽  
Indicator Dilution ◽  
Mathematical Form ◽  
Multiple Indicators ◽  
Multiple Indicator Dilution ◽  
Tracer Movement ◽  
Wide Range ◽  
Multiple Indicator

Multiple indicator dilution (MID) provides a means of quantifying the unidirectional steady-state fluxes of in vivo tracer movement within organs. In this report a MID model of tracer exchange across renal-like epithelia is developed in mathematical form. Six regimes of epithelial transport function are defined on the basis of the relative sizes of the tracer fluxes. Evidence for the existence of each regime has previously been obtained empirically. These are net secretion, net reabsorption, kinetic sink, antiluminal drive, antiluminal equilibration, and antiluminal trapping. By means of the mathematical model, the indicator dilution properties of the six regimes are compared. The principal similarities and differences among the regimes are documented and related to the physical basis of the transport processes. The findings suggest that over a wide range of physiologically meaningful flux magnitudes the functional regimes can be distinguished via existing empirical methods of MID. The model provides an improved basis for carrying out these distinctions in specific applications.

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