Effects of an Experimental Lake Acidification on Zooplankton Feeding Rates and Selectivity

1990 ◽  
Vol 47 (4) ◽  
pp. 772-779 ◽  
Author(s):  
Michael E. Sierszen ◽  
Thomas M. Frost
Keyword(s):  
Population Level ◽  
Plankton Community ◽  
Lake Acidification ◽  
System Level ◽  
Phytoplankton Species ◽  
Fine Scale ◽  
Important Process ◽  
Selective Feeding ◽  
Feeding Rates ◽  
Integrative System

Although the changes in plankton community composition that result from lake acidification have been documented, little is known about processes that accompany these changes. Here we report investigations on an important process, zooplankton herbivory, in an experimentally acidified lake. Acidification from pH 6.2 to 5.2 has not directly impaired the ability of several major taxa to gather food. Acidification may indirectly affect selective feeding behavior, through changes in the relative abundance of phytoplankton species. Dramatic shifts in population-level grazing were not reflected in overall community herbivory, because of complementary changes in populations in the reference and treatment lake basins. Hence, integrative system-level functions may be poorer indicators of perturbation than specific, fine-scale processes.

scholarly journals Exploring a Culture of Health in the Auto Industry

2021 ◽  
Vol 13 (7) ◽  
pp. 3924
Author(s):  
Wendy M. Purcell ◽  
Brian S. Feldman ◽  
Molly Finn ◽  
John D. Spengler
Keyword(s):  
Auto Industry ◽  
Population Level ◽  
Well Being ◽  
System Level ◽  
Senior Executives ◽  
Negative Impacts ◽  
Health Model ◽  
Business In Society ◽  
Corporate Actions ◽  
Societal Expectations

The Culture of Health framework includes four pillars of societal health and well-being influenced by business, namely: consumers; employees and workers in the supply chain; the community, and the environment. The Auto industry was an ideal crucible in which to explore the interface of public health with business given the confluence of the different domains in this sector. The substantial benefits of mobility, especially for the under-resourced, sit alongside negative impacts from emissions, accidents, products and services. Through interviews with 65 senior executives from seven major automakers, corporate actions reflecting health as a strategic agenda were mapped to the Culture of Health model. While most of the companies did not use the language of health explicitly in their strategy, key examples were present across all four pillars. Given the future of mobility relies on the interface of human experience with technology, it is a population-level challenge demanding system-level changes. Ostensibly, a framework for sustainability, the Culture of Health model could help the Auto industry navigate the disruption caused by the global megatrends and changing societal expectations of business in society and transition successfully to a new mobility economy.

Compressed sensorimotor-to-transmodal hierarchical organization in schizophrenia

2021 ◽  
pp. 1-14
Author(s):  
Debo Dong ◽  
Dezhong Yao ◽  
Yulin Wang ◽  
Seok-Jun Hong ◽  
Sarah Genon ◽  
...  
Keyword(s):  
Sensory Information ◽  
Resting State Fmri ◽  
Brain Regions ◽  
High Order ◽  
Hierarchical Organization ◽  
System Level ◽  
Integrative System ◽  
Sensorimotor Region ◽  
Cortical Hierarchy ◽  
High Level

Abstract Background Schizophrenia has been primarily conceptualized as a disorder of high-order cognitive functions with deficits in executive brain regions. Yet due to the increasing reports of early sensory processing deficit, recent models focus more on the developmental effects of impaired sensory process on high-order functions. The present study examined whether this pathological interaction relates to an overarching system-level imbalance, specifically a disruption in macroscale hierarchy affecting integration and segregation of unimodal and transmodal networks. Methods We applied a novel combination of connectome gradient and stepwise connectivity analysis to resting-state fMRI to characterize the sensorimotor-to-transmodal cortical hierarchy organization (96 patients v. 122 controls). Results We demonstrated compression of the cortical hierarchy organization in schizophrenia, with a prominent compression from the sensorimotor region and a less prominent compression from the frontal−parietal region, resulting in a diminished separation between sensory and fronto-parietal cognitive systems. Further analyses suggested reduced differentiation related to atypical functional connectome transition from unimodal to transmodal brain areas. Specifically, we found hypo-connectivity within unimodal regions and hyper-connectivity between unimodal regions and fronto-parietal and ventral attention regions along the classical sensation-to-cognition continuum (voxel-level corrected, p < 0.05). Conclusions The compression of cortical hierarchy organization represents a novel and integrative system-level substrate underlying the pathological interaction of early sensory and cognitive function in schizophrenia. This abnormal cortical hierarchy organization suggests cascading impairments from the disruption of the somatosensory−motor system and inefficient integration of bottom-up sensory information with attentional demands and executive control processes partially account for high-level cognitive deficits characteristic of schizophrenia.

scholarly journals Bridging fisheries management and biodiversity conservation norms: potential and challenges of balancing harvest in ecosystem-based frameworks

2015 ◽  
Vol 73 (6) ◽  
pp. 1659-1667 ◽  
Author(s):  
S. M. Garcia ◽  
J. Rice ◽  
A. Charles
Keyword(s):  
Decision Making ◽  
Fisheries Management ◽  
Biological Diversity ◽  
Population Level ◽  
System Level ◽  
Convention On Biological Diversity ◽  
Management Decision ◽  
Size Spectrum ◽  
Ecosystem Structure ◽  
Management Decision Making

Abstract Balanced harvesting has been proposed as a way for fisheries management to achieve the requirements of both the Law of the Sea Convention (LOSC)—to maintain stocks at the level at which they could produce MSY—and the Convention on Biological Diversity (CBD)—to maintain ecosystem structure and functioning. This paper examines these requirements and briefly presents four system-level relationships (spectra), representing ecosystem structures that might guide management decision-making aiming to meet both requirements. These spectra would fit in the widely accepted frameworks of the Ecosystem Approach enshrined in the CBD and adopted by FAO for Fisheries. A size spectrum, relating biomass to body length, is used as an example to illustrate its potential to support management decision-making—much like present stock-based harvest control rules—in more ecosystem-compliant fishing strategies at a sector or ecosystem level, as a complement to those currently used at a stock/population level.

Population Health as a Complex Adaptive System of Systems

2020 ◽  
pp. 33-44
Author(s):  
Scott E. Page ◽  
Jon Zelner
Keyword(s):  
Population Health ◽  
Systems Approach ◽  
Adaptive System ◽  
Complex Adaptive System ◽  
Disease Outbreaks ◽  
Population Level ◽  
System Of Systems ◽  
System Level ◽  
Multiple Systems ◽  
Complex Adaptive

This chapter advocates a complex adaptive system of systems approach to understanding population-level processes in population health. A complex adaptive system consists of diverse, interacting adaptive entities whose aggregated behaviors result in emergent, system-level patterns and functionalities. A complex adaptive system of systems consists of multiple, connected complex systems. The connections can be hierarchical, horizontal, or a mixture of the two. The authors provide basic definitions, describe common tools of analysis, and introduce illustrative cases. For example, increased obesity levels have no single cause, nor do they arise from a single system. Instead, they arise from the interactions of multiple systems that operate at various levels of scale. Genetics and epigenetics play roles, as do nutrition, general health, advertising, infrastructure, social norms, exercise levels, and, as recent evidence suggests, the ecology of colonies of gut bacteria. Each of these contributors can be modeled as a complex adaptive system and the whole as a system of systems. Similarly, population-level disease outbreaks can be decomposed into separate systems, each with unique dynamics.

The Impact of Consumer Preference Distributions on Dynamic Electricity Pricing for Residential Demand Response

2019 ◽  
Author(s):  
Samuel Dunbar ◽  
Scott Ferguson
Keyword(s):  
Demand Response ◽  
Dynamic Pricing ◽  
Consumer Preferences ◽  
Consumer Preference ◽  
Population Level ◽  
Economic Incentives ◽  
System Level ◽  
Renewable Energy Resources ◽  
Product Use ◽  
The Impact

Abstract Demand Response (DR) is the adjustment of consumer electricity demand through the deployment of one or more strategies, e.g. direct load control, policy implementation, dynamic pricing, or other economic incentives. Widespread implementation of DR is a promising solution for addressing energy challenges such as the integration of intermittent renewable energy resources, reducing capacity cost, and improving grid reliability. Understanding residential consumer preferences for shifting product usage and how these preferences are distributed amongst a population are key to predicting the effectiveness of different DR strategies. In addition, there is a need for a better understanding of how different DR programs, system level objectives, and preference distributions will impact different segments of consumers within a population. Specifically, the impacts on their product use behavior and electricity bill. To address this challenge, a product based approach to modeling consumer decisions about altering their electricity consumption is proposed, which links consumer value to their products, instead of directly to the amount of electricity they consume. This model is then used to demonstrate how population level preference distributions for altering product use impact system level objectives.

scholarly journals Theory and data for simulating fine-scale human movement in an urban environment

2014 ◽  
Vol 11 (99) ◽  
pp. 20140642 ◽  
Author(s):  
T. Alex Perkins ◽  
Andres J. Garcia ◽  
Valerie A. Paz-Soldán ◽  
Steven T. Stoddard ◽  
Robert C. Reiner ◽  
...  
Keyword(s):  
Time Allocation ◽  
Disease Transmission ◽  
Population Level ◽  
Human Movement ◽  
Developed Countries ◽  
Interview Data ◽  
Fine Scale ◽  
Alternative Models ◽  
Individual Based Models ◽  
Location Type

Individual-based models of infectious disease transmission depend on accurate quantification of fine-scale patterns of human movement. Existing models of movement either pertain to overly coarse scales, simulate some aspects of movement but not others, or were designed specifically for populations in developed countries. Here, we propose a generalizable framework for simulating the locations that an individual visits, time allocation across those locations, and population-level variation therein. As a case study, we fit alternative models for each of five aspects of movement (number, distance from home and types of locations visited; frequency and duration of visits) to interview data from 157 residents of the city of Iquitos, Peru. Comparison of alternative models showed that location type and distance from home were significant determinants of the locations that individuals visited and how much time they spent there. We also found that for most locations, residents of two neighbourhoods displayed indistinguishable preferences for visiting locations at various distances, despite differing distributions of locations around those neighbourhoods. Finally, simulated patterns of time allocation matched the interview data in a number of ways, suggesting that our framework constitutes a sound basis for simulating fine-scale movement and for investigating factors that influence it.

Experimental Analysis of the Direct and indirect Effects of an Omnivorous Filter-Feeding Clupeid on Plankton Community Structure

1986 ◽  
Vol 43 (10) ◽  
pp. 1935-1945 ◽  
Author(s):  
Ray W. Drenner ◽  
Stephen T. Threlkeld ◽  
Michael D. McCracken
Keyword(s):  
Particle Size ◽  
Indirect Effects ◽  
Zooplankton Biomass ◽  
Plankton Community ◽  
Direct And Indirect Effects ◽  
Dorosoma Cepedianum ◽  
Feeding Rates ◽  
Filter Feeding ◽  
Menidia Beryllina ◽  
Plankton Community Structure

In laboratory trials, feeding rates of an omnivorous filter-feeding clupeid, Dorosoma cepedianum, increased as a function of particle size, with maximal rates on microspheres, spherical algae, and Zooplankton >40 μm; it did not efficiently feed on filamentous Anabaena flos-aquae. To examine the community level impacts of Dorosoma, we conducted four seasonal outdoor tank experiments of cross-classified design involving two or three densities of Dorosoma and two densities of the zooplanktivorous atherinid fish, Menidia beryllina. We attempted to discriminate between the direct and indirect effects of Dorosoma on phytoplankton by using Menidia to produce indirect effects on phytoplankton by suppressing Zooplankton. Experiments began in November, March, June, and September and lasted for 45–53 d. Dorosoma suppressed most Zooplankton in at least one experiment and enhanced algal standing crops in all four experiments, as indicated by increased algal chlorophyll fluorescence, turbidity, Coulter counts and microscopic algal counts, and decreased Secchi depths. Because in three out of four experiments Menidia suppressed Zooplankton biomass to a greater extent than Dorosoma without enhancing phytoplankton, we reject the hypothesis that the enhancement of phytoplankton by Dorosoma was an indirect effect of Zooplankton biomass suppression.

A Concept Analysis of Transitions of Care for Population Health

2019 ◽  
Vol 33 (3) ◽  
pp. 257-274 ◽  
Author(s):  
Laura Caramanica ◽  
Toby Bressler ◽  
Cecily L. Betz ◽  
Margarete L. Zalon ◽  
Deborah Shelton ◽  
...  
Keyword(s):  
Population Level ◽  
Healthcare Services ◽  
Concept Analysis ◽  
Transitions Of Care ◽  
System Level ◽  
Knowledge Gap ◽  
Conceptual Clarity ◽  
Range Theory ◽  
Antecedents And Consequences ◽  
Number Of Publications

BackgroundCompelling evidence indicates that gaps in quality, safety, and experiences occur when patients encounter transitions across the care continuum. Differences in the organization of healthcare services as well as disparities in health across the globe, may have a unique impact on processes associated with transitions of care for client populations.PurposeIncreased attention to the concept of transitions of care has resulted in disparate meanings and lack of clarity about its nature. Therefore, the purpose of this manuscript is to address this knowledge gap by analyzing the concept of transitions of care at the population level.MethodologyTo address the knowledge gap of what constitutes transitions of care at the population level, a concept analysis was done guided by the methodology of Walker and Avant. A comprehensive search of the literature yielded a small but relevant number of publications.ResultsThis analysis identified four defining attributes, together with antecedents and consequences of transitions of care at the macro-system level of healthcare. A synthesized definition of transitions of care was developed.Implications for PracticeThis analysis provides conceptual clarity for the concept of transitions of care at the macro-system level of care. It can be used to guide the development of a middle-range theory to inform clinical practice and health policy.

Selective predation on cladocerans by common pond insects

1983 ◽  
Vol 61 (4) ◽  
pp. 879-886 ◽  
Author(s):  
Scott D. Cooper
Keyword(s):  
Light Conditions ◽  
Selective Feeding ◽  
Feeding Rates ◽  
Selective Predation ◽  
Anax Junius ◽  
First Instar ◽  
Chaoborus Americanus ◽  
Late Instar ◽  
Insect Predators ◽  
Predation Rates

A variety of common pond insects was presented with a mixture of different size classes of Daphnia magna or different sizes of Daphia pulex, Moina affinis, and Ceriodaphnia sp. in predation trials. Juvenile Belostoma flumineum and most instars of Notonecta undulata and Anax Junius fed at the highest rates on the largest available cladoceran prey, and late-instar Buenoa corfusa fed at the highest rates on prey between 0.8 and 2.0 mm in length. Predation rates of instar IV Chaoborus americanus larvae were highest on Daphnia < 1 mm in length, and lowest on Daphnia > 2 mm in length. First-instar Chaoborus larvae did not eat cladocerans in these trials. The size-selective feeding patterns exhibited by Notonecta adults and late-instar Anax were similar in the light and dark, although overall feeding rates were depressed in the dark. Buenoa, on the other hand, only exhibited size-selective feeding in the light. The results indicate, however, that all of these insect predators can feed in the dark. Predation rates for late-instar Chaoborus larvae were unaffected by light conditions or the presence of filamentous algae. Chaoborus larvae were readily eaten by late-instar Notonecta and Anax.

scholarly journals Integrated, systems metabolic picture of acetone-butanol-ethanol fermentation byClostridium acetobutylicum

2015 ◽  
Vol 112 (27) ◽  
pp. 8505-8510 ◽  
Author(s):  
Chen Liao ◽  
Seung-Oh Seo ◽  
Venhar Celik ◽  
Huaiwei Liu ◽  
Wentao Kong ◽  
...  
Keyword(s):  
Gene Regulation ◽  
Systems Engineering ◽  
Carbon Sources ◽  
Population Level ◽  
Abe Fermentation ◽  
Integrated System ◽  
System Level ◽  
Environmental Cues ◽  
Metabolic Reactions ◽  
Acetone Butanol Ethanol

Microbial metabolism involves complex, system-level processes implemented via the orchestration of metabolic reactions, gene regulation, and environmental cues. One canonical example of such processes is acetone-butanol-ethanol (ABE) fermentation byClostridium acetobutylicum, during which cells convert carbon sources to organic acids that are later reassimilated to produce solvents as a strategy for cellular survival. The complexity and systems nature of the process have been largely underappreciated, rendering challenges in understanding and optimizing solvent production. Here, we present a system-level computational framework for ABE fermentation that combines metabolic reactions, gene regulation, and environmental cues. We developed the framework by decomposing the entire system into three modules, building each module separately, and then assembling them back into an integrated system. During the model construction, a bottom-up approach was used to link molecular events at the single-cell level into the events at the population level. The integrated model was able to successfully reproduce ABE fermentations of the WTC. acetobutylicum(ATCC 824), as well as its mutants, using data obtained from our own experiments and from literature. Furthermore, the model confers successful predictions of the fermentations with various network perturbations across metabolic, genetic, and environmental aspects. From foundation to applications, the framework advances our understanding of complex clostridial metabolism and physiology and also facilitates the development of systems engineering strategies for the production of advanced biofuels.

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