Lower Levels Of Organization Research Articles

Force Spectroscopy of Collagen Fibers to Investigate Their Mechanical Properties and Structural Organization

Tendons are composed of collagen and other molecules in a highly organized hierarchical assembly, leading to extraordinary mechanical properties. To probe the cross-links on the lower level of organization, we used a cantilever to pull substructures out of the assembly. Advanced force probe technology, using small cantilevers (length <20 μm), improved the force resolution into the sub-10 pN range. In the force versus extension curves, we found an exponential increase in force and two different periodic rupture events, one with strong bonds (jumps in force of several hundred pN) with a periodicity of 78 nm and one with weak bonds (jumps in force of <7 pN) with a periodicity of 22 nm. We demonstrate a good correlation between the measured mechanical behavior of collagen fibers and their appearance in the micrographs taken with the atomic force microscope.

Women, Protest, and Revolution: Soldiers' Wives in Russia During 1917

This study explores the role and political impact of soldiers' wives in three Volga provinces of Russia: Nizhnii Novgorod, Kazan, and Tambov between February and October 1917. Despite relatively low levels of formal organization, soldiers' wives made a significant mark on revolutionary politics at a local level. Common grievances, which centred on the inadequacy of state support in the context of rising food prices and shortages, were the defining feature of soldiers' wives as a group. Though they secured little direct representation in government, and did not affiliate with any political parties, they operated collectively to address their grievances, both in petitions and in public demonstrations. Their demands continued to escalate in 1917, and the government was unable to cushion them from Russia's profound economic crisis. Soldiers' wives rejected both Soviet and provisional government leadership as a result, and their alienation contributed to the sense of political crisis that pervaded 1917.

How Music Created a Public

The phrase sphere, originating as a tool for clarifying the nature of a diffuse but perfectly genuine phenomenon, has declined into a piece of slack intellectual shorthand. Its main usefulness today is to illustrate the problems that arise when a deductive formulation is mistakenly assumed to possess explanatory power. In fact it explains nothing at all. If we wish to understand the ways in which private persons learned how to communicate with each other in a public way during the Enlightenment, or the creation of institu tional foundations, independent of the state, for the critical use of reason, we need to descend, with Adrian Johns and David Zaret, to much lower levels of organization and the specific kinds of work it took to sustain them.1 We would also need to accept that different national cultures had very different notions of the public/private distinction and that they acquired these along very dif ferent timelines. My concern here is primarily with the Anglophone working through of this distinction, which is only one strand of a much more complex story, though one that is agreed to have exercised a formative influence. Our problems with the historical public sphere begin with the assumption that it originated from the discursive culture of the London coffeehouses and was enlarged by the freeing of journalism and pamphleteering from prepublica tion censorship. This seems intuitively plausible; yet it has never satisfactorily been explained how such inherently separatist institutions as coffeehouses and newspapers could have been responsible for the creation of a public. In the early seventeenth century, London and through it the nation had, indeed, possessed a single, vast clearinghouse for news and opinion in the form of Paul's walk— the central aisle of the cathedral—to which every Londoner with the itch for news would go in person every day to tap into what had been delivered by rumor, gossip, or personal witness; but this space and the secondary oral information hub of the Royal Exchange were destroyed by the great fire of 1666, and no par ticular venue was ever to recover their dominance. The retreat to the coffee

Analysis of the trophic network of a macrotidal ecosystem: the Bay of Somme (Eastern Channel)

A steady state mass-balance trophic model with Ecopath II was constructed to determine the flow of energy in the trophic network of the Bay of Somme. Parameters were taken or estimated from field and laboratory studies or from literature for fishes and birds. Particulate organic carbon flux has been described in relation to freshwater and tidal inputs. Results of Network Analysis indicate that only 1/8 of the input is from the benthic and pelagic primary production (589 gC m −2 yr −1) and that herbivores use only 6% of this production. An important part of this production is exported and recycled to detritus with a detritivory/herbivory ratio of 8.5. The trophic network of the Bay of Somme has a low level of recycling (FCI=12.2%) and a low level of organization as indicated by several indices like Ascendancy, Capacity, Redundancy and Ascendancy/Capacity. All of these results show an ecosystem with a low maturity, a great production of energy and a low diversity of resources. These results confirm that the Bay of Somme is an ecosystem where detrital flow appears to be the most important input of energy and which exports a significant part of energy (27.9%).

Interaction of granular maize starch with lysophosphatidylcholine evaluated by calorimetry, mechanical and microscopy analysis

In this study we evaluated the thermo-mechanical properties of maize starch pastes (80% wt/wt) under the effect of exogenous lysophosphatidylcholine (LPC) using differential scanning calorimetry (DSC), dynamic mechanical spectrometry (DMS), and scanning electron microscopy (SEM). Particular attention was paid to the development of the amylose-LPC inclusion complex. Results from SEM and DSC showed that with no exogenous LPC, granular maize starch developed the amylose network structure for starch gelling at 80 – 95 8C. In comparison, at 1.86 and 3.35% of LPC, heating up to 130 8C was needed to develop the three-dimensional network required for starch gelling. Results showed that at these LPC concentrations LPC interacted mainly with amylose within the starch granule. At concentrations $ 8.26% the LPC interacted with amylose both inside the granule and on the granule’s surface. At such LPC concentrations heating to 130 8C did not fully develop the starch network structure for gelling. These results suggested that a higher thermal stability was achieved by starch granules because of LPC inclusion complex formation. DSC or DMS did not detect the development of this complex, probably because its formation took place below the onset of gelatinization under conditions of limited molecular mobility. Subsequently, a lower level of organization (i.e. complex in form I) was achieved than in the complex developed at high temperature and water excess (i.e. complex in form II). On the other hand, the changes in the starch granule structure observed by SEM as a function of the time – temperature variable were well described by the phase shift angle ðdÞ rheograms for starch pastes with and without addition of LPC. q 2003 Elsevier Ltd. All rights reserved.

Improving performance: quality costs with a new name?

Juran defined the basic quality problem as “to strike the optimum balance between cost of quality and value of quality for each quality characteristic and to do so in the lower levels of organisation”, explaining that increased conformance reduces the losses which are due to defectives but “the cost of the controls needed for greater conformance rises geometrically as perfection is approached”. Various subsequent models and figures often report, in a dollar measure, the “value” of costs and cost savings. Despite the passing of time since Juran’s explanation that not only dollars can be balanced against dollars but sometimes other measures are just as important, there is often a concern that the real indicator of performance will be what affects the bottom line. This paper discusses different approaches to dealing with the cost of quality and how organisations are attempting to improve performance. The most interesting observation is that what we know as quality costs is clearly being applied successfully under different guises and different names.

Scale Transfer Modeling: Using Emergent Computation for Coupling an Ordinary Differential Equation System with a Reactive Agent Model

This article deals with the coupling of analytical models with individual based models design with the reactive agents paradigm. Such a coupling of models of different natures is motivated by the need to find a way to model scale transfer in large complex systems, i.e. to model how low level of organization can be made to influence upper level and vice versa. This is a fundamental issue, and more particularly in ecological modeling where models are a real scientific tool of investigation. Individuals and populations are not described at the same scale of time and space but it is known that they act on each others. Based on this example, we model individuals in their environment and the population dynamics. While behavior is best modeled using an algorithmic framework (the reactive agent paradigm), population dynamics (because of the number of interacting entities) is best modeled using numerical models. We propose the use of the concept of emergent computation as a framework for coupling heterogeneous formalisms. In the same time, it is crucial to be aware of the consequences of the simplifications and of the choices that are made in the reactive agent model, such as the topology of space and various parameters. In this article, we discuss these issues and our approach on a case study drawn from marine ecology and we show that it is possible to find classical mathematical functional responses with a reactive agent system. Then, we propose a methodology to deal with the coupling of heterogeneous formalism useful in any kind of system modeling.

Biomarkers and community indices as complementary tools for environmental safety

Research on biomarkers as early bioindicators of perturbation in populations and individuals has been gaining ground over the last decade. This ecotoxicological approach relies on the fact that changes occur at low levels of organization before the community is affected and thus they can be monitored to assess environmental safety. Changes may concern behavior, physiology, biochemistry, or genomic structure and functioning, and may impair population dynamics in the long-term. Ecotoxicity studies based on biomarkers allow us to measure the impact of environmental stressors and to easily follow the evolution of the systems towards degradation or restoration. Over and above their use as simple indices of exposure to specific pollutants, biomarkers can give an insight into ecosystem health. The results of our experience in field studies involving ecotoxicologists and ecologists will be presented in order to illustrate the relevance of such an integrating strategy for environmental quality assessment.

Organization structure and fairness perceptions: The moderating effects of organizational level

This research explores the relationship between organizational structure and fairness perceptions. We hypothesized that several dimensions of organizational structure (centralization, formalization, size, and vertical complexity) would influence perceptions of distributive, procedural, and interactional fairness. Further, drawing on social exchange theory, we predict that organizational level will moderate the relationships between structure and fairness perceptions. In particular, we predicted that the effects of structure on justice perceptions would be stronger for individuals at lower organizational levels and weaker for those at higher levels. Results from a sample of 212 participants from 45 departments across 35 work organizations generally supported our predictions. Organizational structure—in particular centralization and formalization—exerted main effects on perceptions of distributive, procedural, and interactional justice. Organizational level was negatively related to both distributive and procedural justice. Finally, as hypothesized, organizational level moderated several of the relationships between structural dimensions and the three types of justice.

Thermal plasticity of skeletal muscle phenotype in ectothermic vertebrates and its significance for locomotory behaviour.

Seasonal cooling can modify the thermal preferenda of ectothermic vertebrates and elicit a variety of physiological responses ranging from winter dormancy to an acclimation response that partially compensates for the effects of low temperature on activity. Partial compensation of activity levels is particularly common in aquatic species for which seasonal temperature changes provide a stable cue for initiating the response. Thermal plasticity of locomotory performance has evolved independently on numerous occasions, and there is considerable phylogenetic diversity with respect to the mechanisms at the physiological and molecular levels. In teleosts, neuromuscular variables that can be modified include the duration of motor nerve stimulation, muscle activation and relaxation times, maximum force and unloaded shortening velocity (V(max)), although not all are modified in every species. Thermal plasticity in V(max) has been associated with changes in myosin ATPase activity and myosin heavy chain (MyHC) composition and/or with a change in the ratio of myosin light chain isoforms. In common carp (Cyprinus carpio), there are continuous changes in phenotype with acclimation temperature at lower levels of organisation, such as MyHC composition and V(max), but a distinct threshold for an effect in terms of locomotory performance. Thus, there is no simple relationship between whole-animal performance and muscle phenotype. The nature and magnitude of temperature acclimation responses also vary during ontogeny. For example, common carp acquire the ability to modify MyHC composition with changes in acclimation temperature during the juvenile stage. In contrast, the thermal plasticity of swimming performance observed in tadpoles of the frog Limnodynastes peronii is lost in the terrestrial adult stage. Although it is often assumed that the adjustments in locomotory performance associated with temperature acclimation enhance fitness, this has rarely been tested experimentally. Truly integrative studies of temperature acclimation are scarce, and few studies have considered both sensory and motor function in evaluating behavioural responses. Developmental plasticity is a special case of a temperature acclimation response that can lead to temporary or permanent changes in morphology and/or physiological characteristics that affect locomotory performance.

Food security and land use deforestation in northern Guatemala

Petén, Guatemala is a lowland tropical frontier that has experienced substantial in-migration and deforestation in recent decades. Efforts to curb deforestation in Petén must be based on a better understanding of farmer strategies and the factors that drive them. This paper outlines some key findings that emerged through a detailed study of these strategies and factors. In particular it discusses the important influence of food security concerns on household strategies, as well as farmers’ growing interest in agricultural intensification, mainly in response to the reduction in the area of forest land available for swidden agriculture. The types of intensification strategies being turned to vary considerably, both among communities/sub-regions, and among households, due to differences in factors that influence the economic feasibility of particular activities. Petén farmers are more concerned about conserving forest than is commonly recognized. However, their ability to reduce pressure on forested areas through adoption of more intensive practices is constrained by weak market conditions and prices, poor agricultural services, low levels of farmer organization, and poverty.

The role of different levels of leadership in predicting self- and collective efficacy: evidence for discontinuity.

This study identified potential discontinuities in the antecedents of efficacy beliefs across levels of analysis, with a particular focus on the role of leadership climate at different organizational levels. Random coefficient modeling analyses conducted on data collected from 2,585 soldiers in 86 combat units confirmed that soldiers' experience, role clarity, and psychological strain predicted self-efficacy to a greater extent than did leadership climate. Also, leadership climate at a higher organizational level related to self-efficacy through role clarity, whereas leadership climate at a lower organizational level related to self-efficacy through psychological strain. Group-level analyses identified leadership climate at a higher organizational level as the strongest predictor of collective efficacy. Theoretical and practical implications and directions for future research are discussed.

Information sources: is there a gender issue?

This study examined gender differences in utilization of information sources within a single large professional services firm. Nine specific sources of information, falling under three broad categories (interpersonal, official company publications, informal) were considered. Respondents indicated how much information they received, their preference for information, and the value of information received, from each source. There were few gender differences at the highest organizational levels (partners, managers) but considerable gender differences at lower organizational levels (professional field staff, secretarial and support staff). Women at lower organizational levels had greater preference for information from all three sources and received more information from official company publications and informal sources.

Initial engagement in parent-centered preventive interventions: A family systems perspective

This article examines factors predicting participant engagement in a parent-centered, substance abuse preventive intervention. One hundred forty-three families assigned to the experimental condition were identified as either “initially engaged” (having attended at least one of the first three sessions) or “not initially engaged.” The groups were compared on demographics, family need for the intervention, barriers to participation, and family systems level variables. Results from hierarchical logistic regression analyses indicate that caregiver need for the intervention and family systems variables significantly predicted initial engagement in the intervention, while demographic variables, stressful life circumstances, and family stress failed to significantly influence engagement. Family systems variables were the strongest predictors of engagement within the full model. Furthermore, ethnic and racial background significantly moderated the effects of family systems variables on engagement in the intervention. For instance, African American families with low levels of family organization were less likely to be engaged than those with high levels of organization. This effect was not as strong for Hispanic caregivers. Implications for recruitment and engagement strategies are discussed.

How to evaluate and predict the ecologic impact of antibiotics: the pharmaceutical industry view from research and development

How to evaluate and predict the ecologic impact of antibiotics: the pharmaceutical industry view from research and development

Boundary Activities in `Boundaryless' Organizations: A Case Study of a Transformation to a Team-Based Structure

This paper reports a case study that analyzes changes in organizational boundary activities carried out in a bank during and after restructuring from a functional to a team-based structure. Results suggest that the need for spanning, buffering, and bringing up boundaries does not disappear as organizations become `boundaryless'. Rather, boundary activities increase in significance and migrate to lower organizational levels. Several propositions are generated for future research.

GENERALIST FEEDING BEHAVIORS OFAEDES SIERRENSISLARVAE AND THEIR EFFECTS ON PROTOZOAN POPULATIONS

The generalist feeding strategy of larvae of the western tree hole mosquito, Aedes sierrensis, is central to understanding the community-level effects of the tritrophic interactions among mosquito larvae, midsized organisms (such as protozoa), and lower-level organisms (such as bacteria and fungi) in west coast phytotelmata. Laboratory microcosm experiments were conducted to characterize the feeding strategies of Ae. sierrensis larvae in the presence of multiple resource types (free-swimming protozoa and substrate-bound particulate material). In our experiment, we quantified the effects of varying instar numbers and profile, resource type, and refuge size on predation of protozoa. Refugia were explicitly modeled in our microcosms, representing the interstitial spaces of leaf litter and the wood lining of natural tree holes. Results from these microcosm experiments suggested that: (1) Even in the absence of larvae, the majority of protozoa resided in the small-volume, resource-rich refugia. There was, however, a strong nonlinear and negative relationship between larval densities in the upper compartment and the protozoan densities in the refuge, suggesting that there was continual movement of protozoa between the two spaces. (2) Fourth instars harvested resources by filter-feeding at a higher rate than second instars. (3) As the level of substrate-bound particulate food was increased, the predation pressure by filter-feeding on the protozoa decreased. (4) As the refuge volume increased, the predation pressure on the protozoa decreased. We constructed a three-state-variable mathematical model describing the generalist feeding behavior of Ae. sierrensis larvae. The model system, with constant predator densities and two prey groups, exhibited full cooperativity; i.e., an increase in protozoa density resulted in a shift toward predation by filter feeding, while an increase in substrate-bound resources resulted in a shift toward predation by browsing. This indirect mutualism is mechanistically distinct from previously published systems and provides a potential mechanism for protozoan persistence in the presence of larval predation.

Evaluating Effects of Contaminants on Fish Health at Multiple Levels of Biological Organization: Extrapolating from Lower to Higher Levels

Effects of environmental stressors such as contaminants on the health of aquatic ecosystems usually involve a series of biological responses ranging from the biomolecular/biochemical to the population and community levels. To establish relationships and to determine the feasibility of extrapolating between higher and lower levels of biological organization, spatial patterns in fish responses to contaminant loading were investigated in a stream receiving point-source discharges of various contaminants near its headwaters. Relationships among fish responses at four major levels of biological organization (biochemical/physiological, individual, population, and community levels) were evaluated relative to patterns in contaminant loading along the spatial gradient of the stream. Both individual and integrated response analysis demonstrated that bioindicators at several levels of biological organization displayed similar downstream patterns in their response to contaminant loading within the stream. Some of the bioindicator responses at lower levels of organization appear to be useful for the ecological risk assessment process because of their sensitivity and apparent relationships to higher levels. By identifying and establishing relationships between levels of biological organization we should be better able to understand the mechanisms of stress responses in ecological systems that could ultimately result in improved predictive capability of ecological risk assessment and also allow for more informed decisions regarding remedial actions.

An examination of variable growth in the loliginid squid Sepioteuthis lessoniana:a whole animal and reductionist approach

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 193:135-141 (2000) - doi:10.3354/meps193135 An examination of variable growth in the loliginid squid Sepioteuthis lessoniana: a whole animal and reductionist approach Jayson M. Semmens1,*, Natalie A. Moltschaniwskyj1,2 1School of Marine Biology and Aquaculture, James Cook University, Townsville, Queensland 4811, Australia 2School of Aquaculture, University of Tasmania, PO Box 1214, Launceston, Tasmania 7250, Australia *E-mail: jayson.semmens@jcu.edu.au ABSTRACT: Squids typically demonstrate considerable plasticity in individual growth rates. However, it is not known if individuals growing at different rates also differ at lower levels of organisation. We wished to determine if Sepioteuthis lessoniana individuals that were larger than predicted for their age differed in their digestive gland and mantle muscle tissue proximal composition or mantle muscle structure, compared with individuals that were smaller for their age than predicted. The residual, the difference between the observed size-at-age and that predicted by the growth equation, was used as a measure of the difference in an individual's lifetime growth from the population average. Individual squid varied considerably in their size-at-age, with juveniles showing less variation than adults. Juveniles had greater concentrations of lipid in their muscle tissue, perhaps due to an emphasis on storing energy reserves in this critical period of their life. Differences in biochemical constituents in both the digestive gland and muscle tissue were not related to the size-at-age of individuals, despite biochemical make-up being the lowest organisational level of growth. This may be due to whole animal growth and changes in biochemical composition occurring on different time scales. There was no relationship between the size-at-age of individuals and average mantle muscle fibre size. A strong relationship, however, existed between the size of mantle muscle blocks and the size-at-age of individuals for both juvenile and adult individuals, suggesting that larger muscle blocks are related to both body size and faster individual growth rates. This study demonstrates a clear relationship between mantle muscle structure and growth and the size-at-age of S. lessoniana individuals. KEY WORDS: Squid · Size-at-age · Condition · Muscle tissue · Digestive gland Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 193. Publication date: February 28, 2000 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 2000 Inter-Research.

Integrating effects of contaminants across levels of biological organization: an overview

Effects of contaminants may occur at all levels oforganization, from molecular to ecosystem-levelresponses. While biochemical and physiologicalalterations in organisms may occur rapidly and areoften stressor-specific, the ecological relevance ofthese suborganismal indicators is uncertain.Alterations in populations and communities havegreater ecological relevance, but a firm mechanisticunderstanding of these responses is often lacking.Developing mechanistic linkages across levels ofbiological organization would greatly improve ourunderstanding of how organisms are affected bycontaminants in nature. The papers in this seriespresent several innovative approaches for integratingeffects of contaminants across levels of biologicalorganization. Authors were asked to describe theecological consequences of responses at lower levelsof organization (biochemical, physiological,individual) and to speculate on the underlyingmechanisms associated with population and communityalterations. The most consistent finding of the fivepapers in this series is that there is no singlespatiotemporal scale or level of biologicalorganization at which ecotoxicological investigationsshould be conducted.