Effect of sediment-organism interactions on hyporheic exchange in streams: role of sediment reworking time

2021 ◽  
Author(s):  
Shivansh Shrivastava ◽  
Michael Stewardson ◽  
Meenakshi Arora
Keyword(s):  
Flow Regime ◽  
Experimental Work ◽  
Laboratory Experiments ◽  
Hyporheic Exchange ◽  
Residence Times ◽  
Sediment Reworking ◽  
Hyporheic Flow ◽  
Mean Residence Times ◽  
Organism Interactions

<p>In-stream faunal organisms constantly interact with their habitat to modify its physical and hydraulic properties. However, little is known about how sediment-organism interactions could modify the hyporheic exchange. Previous experimental work investigating the effects of the activities of faunal organisms on exchange across the sediment-water interface has been largely conducted in small mesocosms or infiltration columns that do not represent the lotic environment adequately. Therefore, the experimental findings from these studies may not be transferable to flowing water environments (e.g., streams). Our previous experimental work demonstrated that sediment reworking by macroinvertebrates could significantly alter the hyporheic flux, mean residence times, and depth of exchange in streambeds. In this work, we explore how sediment-organism contact time influence the effect of the activities of model organisms, Lumbriculus variegatus, on the hyporheic flow regime. We conduct laboratory experiments in re-circulating flumes subject to different sediment reworking times (5 and 10 days). The hyporheic flow characteristics in these flumes were studied by conducting dye tracer tests after the bed sediments were reworked. Deposition of fecal pellets and holes/burrows dug by sample organisms were visible at the bed surface in both the experimental flumes. The flume reworked for a longer time exhibited higher hyporheic flux, longer median/mean residence times, and deeper depth of solute penetration compared to the flume reworked for a shorter period. The modification of hyporheic flow regime to different degrees depending on the sediment reworking times has direct relevance to the biogeochemistry in hyporheic zones, and thus on the overall quality of surface and sub-surface waters. We advocate that more intensive laboratory experiments and field investigations must be conducted to support the findings from our study and advance our understanding of the role of the activities of faunal organisms on fluvial ecosystem functioning.</p>

THE ROLE OF LITERACY METHODS IN MASTERING OF WRITTEN LANGUAGE BY STUDENTS WITH DEVELOPMENTAL DYSLEXIA

2019 ◽  
Vol 7 (1) ◽  
pp. 10-18
Author(s):  
Tsvetanka Tsenova
Keyword(s):  
Experimental Work ◽  
Developmental Dyslexia ◽  
Reading Skills ◽  
Writing Skills ◽  
Written Language ◽  
Reading And Writing ◽  
Empirical Verification ◽  
Literacy Methods ◽  
The Relationship

This article focuses on the relationship between literacy methods applied at school and the emergence of serious difficulties in mastering reading and writing skills that shape the developmental dyslexia. The problem was analyzed theoretically and subjected to empirical verification. Experimental work was presented which aims to study the phonological and global reading skills of 4- th grade students with and without dyslexia. Better global reading skills have been demonstrated in all tested children, and this is much more pronounced in those with dyslexia than their peers without disorders. Hence, the need to develop a special, corrective methodology for literacy of students with developmental dyslexia consistent with their psychopathological characteristics.

Observation and Experimentation

2018 ◽  
Author(s):  
Massimiliano Di Ventra
Keyword(s):  
Laboratory Experiments ◽  
The Difference

This chapter expands on the previous one on the role of experiments in Science. It explains the difference between observations of phenomena and controlled laboratory experiments.

Role of Reynolds and Archimedes numbers in particle-fluid flows

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Haim Kalman
Keyword(s):  
Flow Regime ◽  
Power Function ◽  
Fluid Flows ◽  
Limited Range ◽  
Operating Conditions ◽  
Pneumatic Conveying ◽  
Particulate Materials ◽  
Simple Power ◽  
Simple Power Function

AbstractAny scientific behavior is best represented by nondimensional numbers. However, in many cases, for pneumatic conveying systems, dimensional equations are developed and used. In some cases, many of the nondimensional equations include Reynolds (Re) and Froude (Fr) numbers; they are usually defined for a limited range of materials and operating conditions. This study demonstrates that most of the relevant flow types, whether in horizontal or vertical pipes, can be better described by Re and Archimedes (Ar) numbers. Ar can also be used in hydraulic conveying systems. This paper presents many threshold velocities that are accurately defined by Re as a simple power function of Ar. Many particulate materials are considered by Ar, thereby linking them to a common behavior. Using various threshold velocities, a flow regime chart for horizontal conveying is presented in this paper.

How much would you like to pay? Trust, reciprocity and prosocial motivations in El trato

2012 ◽  
Vol 51 (3) ◽  
pp. 389-417 ◽  
Author(s):  
Francisco J León ◽  
José A Noguera ◽  
Jordi Tena-Sánchez
Keyword(s):  
Social Science ◽  
External Validity ◽  
Laboratory Experiments ◽  
Social Science Research ◽  
Science Research ◽  
Trust Game ◽  
Sales Strategy ◽  
Pay What You Want ◽  
Natural Settings

Prosocial motivations and reciprocity are becoming increasingly important in social-science research. While laboratory experiments have challenged the assumption of universal selfishness, the external validity of these results has not been sufficiently tested in natural settings. In this article we examine the role of prosocial motivations and reciprocity in a Pay What You Want (PWYW) sales strategy, in which consumers voluntarily decide how much to pay for a product or service. This article empirically analyses the only PWYW example in Spain to date: the El trato (‘The deal’) campaign launched by the travel company Atrápalo, which offered different holiday packages under PWYW conditions in July 2009. Our analysis shows that, although the majority of the customers did not behave in a purely self-interested manner, they nonetheless did so in a much higher proportion than observed in similar studies. We present different hypotheses about the mechanisms that may explain these findings. Specifically, we highlight the role of two plausible explanations: the framing of the campaign and the attribution of ‘hidden’ preferences to Atrápalo by its customers, which undermined the interpretation of El trato as a trust game.

The Effect of Face Consciousness on Consumption of Counterfeit Luxury Goods

2014 ◽  
Vol 42 (6) ◽  
pp. 1007-1014 ◽  
Author(s):  
Yun-Qing Chen ◽  
Hong Zhu ◽  
Meng Le ◽  
Yi-Zhen Wu
Keyword(s):  
Purchase Intention ◽  
Laboratory Experiments ◽  
Positive Influence ◽  
Luxury Goods ◽  
Intention To Purchase ◽  
Luxury Item ◽  
Moderating Role ◽  
Chinese Undergraduates ◽  
Significant Positive Influence

We conducted 3 laboratory experiments to determine how face consciousness influences consumption of counterfeit luxury goods, along with the moderating roles of usage occasion and brand prominence. The participants in the first study were 138 Chinese undergraduates who were allocated to a 2 × 2 design to evaluate their intention to purchase a counterfeit luxury item that would be used either in public or in private. In Studies 2 and 3, using two 2 × 2 designs we evaluated the purchase intention of the participants (132 and 136, respectively) in order to investigate the moderating role of brand prominence. The results showed that participants' face consciousness had a significant positive influence on intention to purchase counterfeit luxury goods. In addition, the products' usage occasion and brand prominence positively moderated the influence that face consciousness had on counterfeit luxury item purchase intention of our participant groups.

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