Ecological Studies on Growth-Form in Bryophytes: II. Experimental Studies on Growth-Form in Mosses

1957 ◽  
Vol 45 (3) ◽  
pp. 721 ◽  
Author(s):  
Evelyn M. Birse
Keyword(s):  
Growth Form ◽  
Experimental Studies ◽  
Ecological Studies

Modeling and verification of selective sludge discharge as the controlling factor for aerobic granulation

2010 ◽  
Vol 62 (10) ◽  
pp. 2442-2449
Author(s):  
A. J. Li ◽  
T. Zhang ◽  
X. Y. Li
Keyword(s):  
Laboratory Experiments ◽  
Growth Form ◽  
Experimental Studies ◽  
Controlling Factor ◽  
Substrate Uptake ◽  
Granulation Process ◽  
Sludge Flocs ◽  
Dense Granules ◽  
Biomass Dynamics ◽  
Aerobic Sludge

Mathematical simulation and laboratory experiments were conducted to investigate the controlling factor for aerobic sludge granulation. A model was used to describe the biomass dynamics during the granulation process. The simulation results indicate that the selective discharge of small and loose sludge flocs is the key controlling factor for granulation. In the experimental studies, tests were conducted with four batch column reactors (BCR) that were seeded with both activated sludge flocs and mature granules. Three different sludge discharge methods were tested, including unselective discharge of mixed sludge, selective discharge of small and slow-settling flocs, and selective discharge of settled dense sludge. The results show that mixed sludge discharge and discharge of dense sludge resulted in disappearance of granules from the reactors. Only selective discharge of small and slow-settling sludge flocs led to complete granulation. Small and loose sludge flocs were found to have a clear advantage over large and dense granules in substrate uptake. It can be concluded that selective discharge of loose flocs removes these competitors in suspended-growth mode from the reactors and makes the substrate more available for uptake and utilization by the biomass in attached-growth form, leading to granulation.

Another route to broadening the scope of social psychology: Ecologically valid research

2004 ◽  
Vol 27 (3) ◽  
pp. 339-340 ◽  
Author(s):  
Samuel D. Gosling
Keyword(s):  
Social Psychology ◽  
Real World ◽  
Social Life ◽  
Laboratory Experiments ◽  
Experimental Studies ◽  
Ecological Studies ◽  
The Real ◽  
Existence Proofs ◽  
Mere Existence

An imbalance is identified in social psychology between controlled experimental studies (which are common) and real-world, ecologically valid studies (which are rare). The preponderance of experimental studies (which provide mere existence proofs and lack realism) helps fuel social psychology's fault-finding focus. Laboratory experiments and ecological studies should be pursued jointly to examine social life in the real world.

scholarly journals Genotypic variability enhances the reproducibility of an ecological study

2016 ◽  
Author(s):  
Alexandru Milcu ◽  
Ruben Puga-Freitas ◽  
Aaron M. Ellison ◽  
Manuel Blouin ◽  
Stefan Scheu ◽  
...  
Keyword(s):  
Environmental Conditions ◽  
Ecological Study ◽  
Experimental Studies ◽  
Ecological Studies ◽  
Scientific Disciplines ◽  
Microcosm Study ◽  
Laboratory Microcosm ◽  
Controlled Environments ◽  
Growth Chambers ◽  
Study Designs

Many scientific disciplines currently are experiencing a “reproducibility crisis” because numerous scientific findings cannot be repeated consistently. A novel but controversial hypothesis postulates that stringent levels of environmental and biotic standardization in experimental studies reduces reproducibility by amplifying impacts of lab-specific environmental factors not accounted for in study designs. A corollary to this hypothesis is that the deliberate introduction of controlled systematic variability (CSV) in experimental designs can increase reproducibility. We tested this hypothesis using a multi-laboratory microcosm study in which the same ecological experiment was repeated in 14 laboratories across Europe. Each laboratory introduced environmental and genotypic CSV within and among replicated microcosms established in either growth chambers (with stringent control of environmental conditions) or glasshouses (with more variable environmental conditions). The introduction of genotypic CSV led to lower among-laboratory variability in growth chambers, indicating increased reproducibility, but had no significant effect in glasshouses where reproducibility also was lower. Environmental CSV had little effect on reproducibility. Although there are multiple causes for the “reproducibility crisis”, deliberately including genetic variation may be a simple solution for increasing the reproducibility of ecological studies performed in controlled environments.

Understanding krill growth and aging: the contribution of experimental studies

2000 ◽  
Vol 57 (S3) ◽  
pp. 168-177 ◽  
Author(s):  
Stephen Nicol
Keyword(s):  
Population Biology ◽  
Experimental Studies ◽  
Euphausia Superba ◽  
Future Research ◽  
Ecological Studies ◽  
Experimental Approaches ◽  
Increasing Knowledge ◽  
Growth And Aging ◽  
Experimental Findings

Krill have been viewed as difficult animals to examine experimentally. Consequently, most information on growth and age of these pelagic crustaceans has come from demographic studies on preserved specimens. Only one species of krill, Euphausia superba, has been intensively studied in the laboratory, but the experimental findings on growth and age from these studies have fundamentally altered our perceptions of the population biology of this species. Most other species of krill remain in the preexperimental phase of understanding; thus, there remain considerable uncertainties regarding their growth and longevity. Unfortunately, these uncertainties are often ignored in ecological studies. In this paper, I have examined the role that experimental studies have played in increasing knowledge of the population biology of krill, particularly in the fields of growth and aging. I have indicated where discrepancies exist between field-based and experimental approaches and I outline some approaches for exploring these discrepancies and suggest some potentially fruitful areas for future research.

3-D reconstruction and analysis of mammalian mitotic spindle structure

1992 ◽  
Vol 50 (1) ◽  
pp. 578-579
Author(s):  
Kent McDonald ◽  
David Mastronarde ◽  
Rubai Ding ◽  
Eileen O'Toole ◽  
J. Richard McIntosh
Keyword(s):  
Cross Sections ◽  
Mitotic Spindle ◽  
Experimental Studies ◽  
Video Camera ◽  
Three Dimensions ◽  
Mitotic Spindles ◽  
Black And White ◽  
Reconstruction Methods ◽  
Spindle Structure ◽  
Tissue Culture Line

Mammalian spindles are generally large and may contain over a thousand microtubules (MTs). For this reason they are difficult to reconstruct in three dimensions and many researchers have chosen to study the smaller and simpler spindles of lower eukaryotes. Nevertheless, the mammalian spindle is used for many experimental studies and it would be useful to know its detailed structure.We have been using serial cross sections and computer reconstruction methods to analyze MT distributions in mitotic spindles of PtK cells, a mammalian tissue culture line. Images from EM negatives are digtized on a light box by a Dage MTI video camera containing a black and white Saticon tube. The signal is digitized by a Parallax 1280 graphics device in a MicroVax III computer. Microtubules are digitized at a magnification such that each is 10-12 pixels in diameter.

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