Long-term feedback and differential feedback effects in nonmetric multiple-cue probability learning

1977 ◽  
Vol 22 (2) ◽  
pp. 116-128 ◽  
Author(s):  
N. John Castellan ◽  
Michael Swaine
Keyword(s):  
Probability Learning ◽  
Feedback Effects

Long-term probability learning with a random schedule of reinforcement.

1968 ◽  
Vol 78 (3, Pt.1) ◽  
pp. 442-455 ◽  
Author(s):  
Morton P. Friedman ◽  
Edward C. Carterette ◽  
Norman H. Anderson
Keyword(s):  
Probability Learning ◽  
Schedule Of Reinforcement ◽  
Random Schedule

Effects of corticosterone on the secretion of corticotrophin-releasing factor, arginine vasopressin and oxytocin into hypophysial portal blood in long-term hypophysectomized rats

1991 ◽  
Vol 129 (1) ◽  
pp. 91-98 ◽  
Author(s):  
W. J. Sheward ◽  
G. Fink
Keyword(s):  
Arginine Vasopressin ◽  
Portal Blood ◽  
Blood Collection ◽  
Continuous Administration ◽  
Feedback Effects ◽  
Corticotrophin Releasing Factor ◽  
Hypophysectomized Rats ◽  
Hypophysial Portal ◽  
Intact Rats

ABSTRACT To investigate the feedback effects of corticosterone on the secretion of corticotrophin-releasing factor-41 (CRF-41), oxytocin and arginine vasopressin (AVP), hypophysial portal vessel blood was collected from control (intact) and long-term (6–8 weeks) hypophysectomized rats. In preliminary experiments in rats anaesthetized with urethane, long-term hypophysectomy resulted in a significant increase in the secretion of oxytocin and AVP; the hypothalamic contents of oxytocin and AVP were also increased in comparison with pituitary-intact rats. In long-term hypophysectomized rats anaesthetized with sodium pentobarbitone, but not with urethane, the output of CRF-41 into portal blood was increased twofold in comparison with that in control rats. In long-term hypophysectomized rats anaesthetized with pentobarbitone, the i.v. infusion of corticosterone (7·2 nmol/min) for a 2 h period of portal blood collection did not alter the secretion of CRF-41, oxytocin or AVP into portal blood; however, the secretion of CRF-41 and, to a lesser extent, AVP was significantly reduced in hypophysectomized rats by continuous corticosterone replacement, by a pellet of corticosterone implanted s.c. for 5 days before portal blood collection. These results confirm that the secretion of CRF-41 is differently affected by the anaesthetics urethane and pentobarbitone, and in long-term hypophysectomized rats show (i) that there were no apparent feedback effects of corticosterone infusion over a 2 h period on the secretion of any of the peptides studied, (ii) that late delayed feedback effects of continuous administration of corticosterone are mediated by a reduction in CRF-41 and AVP output, and (iii) that corticosterone has no effects on oxytocin secretion into portal blood. Journal of Endocrinology (1991) 129, 91–98

scholarly journals Advancing catchment hydrology to deal with predictions under change

2014 ◽  
Vol 18 (2) ◽  
pp. 649-671 ◽  
Author(s):  
U. Ehret ◽  
H. V. Gupta ◽  
M. Sivapalan ◽  
S. V. Weijs ◽  
S. J. Schymanski ◽  
...  
Keyword(s):  
Earth Science ◽  
Large Error ◽  
Temporal Aggregation ◽  
Catchment Hydrology ◽  
Feedback Effects ◽  
Engineering Discipline ◽  
Time Invariance ◽  
Spatio Temporal ◽  
System Configurations

Abstract. Throughout its historical development, hydrology as an earth science, but especially as a problem-centred engineering discipline has largely relied (quite successfully) on the assumption of stationarity. This includes assuming time invariance of boundary conditions such as climate, system configurations such as land use, topography and morphology, and dynamics such as flow regimes and flood recurrence at different spatio-temporal aggregation scales. The justification for this assumption was often that when compared with the temporal, spatial, or topical extent of the questions posed to hydrology, such conditions could indeed be considered stationary, and therefore the neglect of certain long-term non-stationarities or feedback effects (even if they were known) would not introduce a large error.

scholarly journals The Interplay between Breeding and Thermal Feedback in a Molten Chlorine Fast Reactor

Energies ◽  
2020 ◽  
Vol 13 (7) ◽  
pp. 1609
Author(s):  
Bruno Merk ◽  
Anna Detkina ◽  
Dzianis Litskevich ◽  
Seddon Atkinson ◽  
Gregory Cartland-Glover
Keyword(s):  
Spent Nuclear Fuel ◽  
Self Control ◽  
Automated Control ◽  
Feedback Effects ◽  
Term Operation ◽  
Thermal Feedback ◽  
Load Following ◽  
Zero Carbon ◽  
Positive Outlook

The energy trilemma and UN SDG 7 form the key drivers for the future of all kinds of energy research. In nuclear technology, molten salt reactors are an interesting option, since they can offer a game-changing approach to deliver an attractive, highly sustainable option for a zero-carbon society by providing sufficient breeding for a self-sustained long-term operation based on spent nuclear fuel from existing reactors while being able to be controlled ideally by inherent processes. To achieve these goals, several basic challenges have already been identified and worked on; demonstration of sufficient breeding and development of a demand driven salt clean up system. This study follows up on the opportunity for reactor control based on inherent feedback mechanisms. It is demonstrated that the investigated sodium chloride-uranium chloride-based systems can feasibly deliver a thermal feedback effect, which is strong enough, to compensate for the critically change due to breeding and fission product accumulation for two different compositions. The achieved results provide a very positive outlook on the system inherent ability for reactor self-control and even for the feasibility of a load following operation based on inherent feedback effects instead of massive and costly manual/automated control system operation.

scholarly journals Biotic interactions, community assembly, and eco-evolutionary dynamics as drivers of long-term biodiversity–ecosystem functioning relationships

2019 ◽  
Vol 5 ◽  
Author(s):  
Nico Eisenhauer ◽  
Michael Bonkowski ◽  
Ulrich Brose ◽  
Francois Buscot ◽  
Walter Durka ◽  
...  
Keyword(s):  
Community Assembly ◽  
Ecosystem Functioning ◽  
Biotic Interactions ◽  
Research Unit ◽  
Ecosystem Functions ◽  
Feedback Effects ◽  
Biodiversity Change ◽  
Diversity Effects ◽  
The Jena Experiment

The functioning and service provisioning of ecosystems in the face of anthropogenic environmental and biodiversity change is a cornerstone of ecological research. The last three decades of biodiversity–ecosystem functioning (BEF) research have provided compelling evidence for the significant positive role of biodiversity in the functioning of many ecosystems. Despite broad consensus of this relationship, the underlying ecological and evolutionary mechanisms have not been well understood. This complicates the transition from a description of patterns to a predictive science. The proposed Research Unit aims at filling this gap of knowledge by applying novel experimental and analytical approaches in one of the longest-running biodiversity experiments in the world: the Jena Experiment. The central aim of the Research Unit is to uncover the mechanisms that determine BEF relationships in the short- and in the long-term. Increasing BEF relationships with time in long-term experiments do not only call for a paradigm shift in the appreciation of the relevance of biodiversity change, they likely are key to understanding the mechanisms of BEF relationships in general. The subprojects of the proposed Research Unit fall into two tightly linked main categories with two research areas each that aim at exploring variation in community assembly processes and resulting differences in biotic interactions as determinants of the long-term BEF relationship. Subprojects under “Microbial community assembly” and “Assembly and functions of animal communities” mostly focus on plant diversity effects on the assembly of communities and their feedback effects on biotic interactions and ecosystem functions. Subprojects under “Mediators of plant-biotic interactions” and “Intraspecific diversity and micro-evolutionary changes” mostly focus on plant diversity effects on plant trait expression and micro-evolutionary adaptation, and subsequent feedback effects on biotic interactions and ecosystem functions. This unification of evolutionary and ecosystem processes requires collaboration across the proposed subprojects in targeted plant and soil history experiments using cutting-edge technology and will produce significant synergies and novel mechanistic insights into BEF relationships. The Research Unit of the Jena Experiment is uniquely positioned in this context by taking an interdisciplinary and integrative approach to capture whole-ecosystem responses to changes in biodiversity and to advance a vibrant research field.

On the importance of including soil nutrient feedback effects for predicting ecosystem carbon exchange

2003 ◽  
Vol 30 (2) ◽  
pp. 223 ◽  
Author(s):  
Miko U. F. Kirschbaum ◽  
Guillaume Simioni ◽  
Belinda E. Medlyn ◽  
Ross E. McMurtrie
Keyword(s):  
Soil Nutrient ◽  
Nutrient Supply ◽  
Carbon Stocks ◽  
Carbon Gain ◽  
Feedback Effects ◽  
Ecosystem Carbon ◽  
Foliar Nutrient ◽  
And Storage ◽  
Ecosystem Carbon Exchange

To grow, plants need both carbon, which is fixed in photosynthesis, and inorganic nutrients, which are generally obtained from the soil. Much interest currently exists in trying to understand the uptake and storage of carbon by terrestrial ecosystems. This paper investigates to what extent carbon gain and storage are modified by soil nutrient availability. This issue is investigated in relation to both short-term carbon fluxes on the time scale of interannual variability and long-term ecosystem carbon stocks on time scales of several thousand years.We conclude from simulations with an ecosystem model (CenW) that interannual variations in carbon gain can be significantly affected by feedback effects through the nutrient cycle. This feedback effect operates principally through an imbalance between carbon and nutrient dynamics. In years that allow high carbon gain, nutrient supply typically does not match the increased carbon supply so that foliar nutrient concentrations are reduced. This lowers productivity below that which could be expected if foliar nutrient concentration remained the same. The importance of these feedback effects is shown to be greatest at intermediate levels of water availability and nutrient supply, and is relatively more important for net ecosystem carbon exchange than for net primary production.We conclude that the long-term build-up of carbon stocks in ecosystems is often controlled by the rate at which nutrients can be gained. This conclusion is based on data from published studies showing that the slow build-up of carbon matches the gain in nitrogen, phosphorus and sulfur, and on our simulations of system carbon stocks in response to fertiliser addition.The paper concludes with a discussion of the importance and feasibility of including these processes into models at different scales, including the broad continental scale. For modelling net ecosystem exchange for Australia, it is regarded as feasible and desirable to use models that are constrained by these system-internal feedback effects. Such models have already been used for large-scale simulations in Australia and other countries.

Prejudice and Progress in Baseball

2012 ◽  
pp. 2-20
Author(s):  
Stephen J. K. Walters
Keyword(s):  
Willingness To Pay ◽  
Labor Supply ◽  
Racial Bias ◽  
Economic Consequences ◽  
Empirical Literature ◽  
Ceteris Paribus ◽  
Feedback Effects ◽  
Integration Period ◽  
Short And Long Term

This article explores the organized baseball's racial record as far back as the 1880s, when segregation took root in baseball, through Branch Rickey's hiring of Jackie Robinson in 1947, up to the present day. It describes how baseball became segregated and segregation's feedback effects on black players' labor supply decisions. It presents data on black-white earning differences prior to reintegration of the sport. It addresses why reintegration took so long and how it ultimately occurred. Robinson's breakthrough and its immediate aftermath, and the empirical literature on the post-integration period are evaluated. The existence of an active market for baseball memorabilia has enabled researchers to test for fan bias in the form of a willingness to pay more for products featuring white (black) players, ceteris paribus. Baseball has taught a great deal about how complicated and persistent are racial bias' effects, and about the short- and long-term economic consequences of discrimination.

scholarly journals Choice and the Relationship between Identities and Behaviour for Mothers with Pre-School Children: Some Implications for Policy from a UK Study

2004 ◽  
Vol 33 (3) ◽  
pp. 455-478 ◽  
Author(s):  
SUSAN HIMMELWEIT ◽  
MARIA SIGALA
Keyword(s):  
School Children ◽  
Quantitative Methods ◽  
Child Poverty ◽  
Policy Implications ◽  
Feedback Effects ◽  
Qualitative And Quantitative Methods ◽  
The Social ◽  
The Individual ◽  
The Relationship

This article reports on the findings and policy implications of a UK study that used both qualitative and quantitative methods to investigate mothers' decision-making with respect to the interlinked issues of the care of their pre-school children and their own employment. Mothers were found to have both internal and external constraints on their decisions. In the three areas of finances, childcare and working time, both personal identities and external circumstances limited mothers' choices. However, neither external circumstances nor identities were fixed. Behaviour and identities were therefore adjusted to each other, giving rise to feedback effects at both the individual and the social level.While the constraints of identity limit the direct effectiveness of some policies, the long-term effectiveness of others may be enhanced by positive feedback arising from attitudes changing along with behaviour. A ‘policy multiplier’ is defined as the ratio of such indirect to direct effects. This is likely to be greater for enabling policies that lift existing constraints and enable choices that were previously not available, than for coercive policies that impose new constraints on behaviour. The article examines the implications of such feedback effects for developing policy that expands the choices available to mothers in the short term, reduces the costs of motherhood, and meets the government's long-term objectives of reducing child poverty and increasing employment.

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