scholarly journals The Prediction of Waste Water Dilution by a Long-Term Tracer Experiment

1976 ◽  
Vol 7 (4) ◽  
pp. 231-244 ◽  
Author(s):  
Risto Kuoppamäki ◽  
Arto Muurinen
Keyword(s):  
Waste Water ◽  
Pulp Mill ◽  
Complex Form ◽  
Tracer Experiment ◽  
Injection Time ◽  
Short Term ◽  
Tracer Injection ◽  
Long Term Experiment ◽  
Water Dilution

In general tracer experiments made for the evaluation of waste water dilution in recipients have been of short-term type, with the tracer having an injection time that is markedly less than the time scale of flowpattern changing. In typical Finnish lakes and coastal waters, with complicated topography and frequently varying winds, the results from short term experiments have proved to be of rather limited value. In view of this, a study has been made of the possibility of measuring the dilution under such circumstances, by means of a long-term experiment with a tracer injection time extending over several weeks. Indium was considered to be the most suitable tracer for such an experiment; the complex form of indium is preferable to ionic solution to ensure reliability in the results. The applicability of the method in the fields is illustrated by an example of a waste-water dilution study made for a pulp mill under construction. Two subsequent long-term experiments were conducted for measurement of the dilution of waste water from two alternative discharge points. The results obtained gave a very clear illustration of the local average dilution ratios, and allowed a reliable comparison being made between the two alternative discharge points.

scholarly journals Statistical concepts in the theory of bacterial mutation

1953 ◽  
Vol 51 (2) ◽  
pp. 162-184 ◽  
Author(s):  
P. Armitage
Keyword(s):  
Mutation Rate ◽  
Phenotypic Expression ◽  
Theoretical Distribution ◽  
Mutation Rates ◽  
Safe Procedure ◽  
Short Term ◽  
Mutant Type ◽  
Bacterial Populations ◽  
Long Term Experiment

This paper is a short exposition of the mathematical and statistical theory of the growth of bacterial populations subject to mutation.A mathematical model for the long-term development of a mixed population with two types of organism is proposed. The proportion of organisms which are of the mutant type eventually approaches an asymptotic value, which is independent of the initial composition of the population. A procedure is outlined for estimating the forward and backward mutation rates from a long-term experiment.The exact interpretation of the constants representing mutation rates requires some assumption about the point of time, during an individual life cycle, at which mutations occur. The usual assumption is that mutations can occur with equal frequency at all instants during the cycle.In short-term experiments, in which the proportion of mutants is at all times negligible, it is important to consider the variation between the numbers of mutants developing in replicate cultures. The theoretical distribution of Lea & Coulson may be disturbed by the failure of any one of a number of assumptions; the effects of such disturbances are considered in some detail.Various methods of estimating the mutation rate from an observed series of replicate cultures are examined. Two of the main sources of disturbance of the theoretical distribution may be delay of phenotypic expression, and the existence of multinucleate cells with dominant mutation. These factors affect particularly the lower tail of the distribution, and it is suggested that a fairly safe procedure may be to estimate the mutation rate from the upper quartile of the observed distribution. Tables 3 and 4 enable the estimate of the mutation rate, together with 95% confidence limits, to be readily calculated.

scholarly journals Long-term resource addition to a detrital food web yields a pattern of responses more complex than pervasive bottom-up control

2017 ◽  
Author(s):  
Kendra L. Lawrence ◽  
David H Wise
Keyword(s):  
Field Experiments ◽  
Abiotic Factors ◽  
Short Term ◽  
Bottom Up ◽  
Term Experiment ◽  
Two Factors ◽  
Long Term Experiment ◽  
Short Term Experiment ◽  
Univariate Analyses

Background. Theory predicts strong bottom-up control in detritus-based food webs, yet field experiments with detritus-based terrestrial systems have uncovered contradictory evidence regarding the strength and pervasiveness of bottom-up control processes. Two factors likely leading to contradictory results are experiment duration, which influences exposure to temporal variation in abiotic factors such as rainfall and affects the likelihood of detecting approach to a new equilibrium; and openness of the experimental units to immigration and migration. To investigate the contribution of these two factors, we conducted a long-term experiment with open and fenced plots in the forest that was the site of an earlier, short-term experiment (3.5 months) with open plots (Chen & Wise 1999) that produced evidence of strong bottom-up control for 14 taxonomic groupings of primary consumers of litter and fungi (microbi-detritivores) and their predators. Methods. We added artificial high-quality detritus to ten 2 x 2-m forest-floor plots at bi-weekly intervals from April through September in three consecutive years (Supplemented treatment). Ten comparable Ambient plots were controls. Half of the Supplemented and Ambient plots were enclosed by metal fencing. Results. Arthropod community structure (based upon 18 response variables) diverged over time between Supplemented and Ambient treatments, with no effect of Fencing on the multivariate response pattern. Fencing possibly influenced only ca. 20% of the subsequent univariate analyses. Multi- and univariate analyses revealed bottom-up control by fall of Year 1 of some, but not all, microbi-detritivores and predators. During the following two years the pattern of responses became more complex than that observed by Chen & Wise (1999). Some taxa showed consistent bottom-up control whereas many did not. Variation across years could not be explained completely by differences in rainfall because some taxa exhibited negative, not positive, responses to detrital supplementation. Discussion. Our 3-yr experiment did not confirm the conclusion of strong, pervasive bottom-up control of microbi-detritivores and predators reported by Chen and Wise (1999). Our longer-term experiment revealed a more complex pattern of responses, a pattern much closer to the range of outcomes reported in the literature for many short-term experiments. Much of the variation in responses across studies likely reflects variation in factors such as rainfall and the quality of added detritus. Nevertheless, it is also possible that long-term resource enhancement can drive a community towards a new equilibrium state that differs from what would have been predicted from the initial short-term responses exhibited by primary and secondary consumers.

scholarly journals Sulfur-Based Denitrification in Streambank Subsoils in a Headwater Catchment Underlain by Marine Sedimentary Rocks in Akita, Japan

2021 ◽  
Vol 9 ◽  
Author(s):  
Atsushi Hayakawa ◽  
Hitoshi Ota ◽  
Ryoki Asano ◽  
Hirotatsu Murano ◽  
Yuichi Ishikawa ◽  
...  
Keyword(s):  
Bacterial Flora ◽  
Terrestrial Ecosystems ◽  
Stoichiometric Ratio ◽  
Short Term ◽  
Incubation Experiments ◽  
Long Term Experiment ◽  
Sulfide Content ◽  
Sulfur Oxidizing ◽  
Headwater Catchment

Sulfur-based denitrification may be a key biogeochemical nitrate (NO3−) removal process in sulfide-rich regions, but it is still poorly understood in natural terrestrial ecosystems. We examined sulfur-driven NO3− reduction using streambank soils in a headwater catchment underlain by marine sedimentary rock in Akita, Japan. In a catchment exhibiting higher sulfide content in streambed sediment, we sampled two adjacent streambank soils of streambank I (two layers) and of streambank II (eight layers). Anaerobic long-term incubation experiments (40 days, using soils of streambank I) and short-term incubation experiments (5 days, using soils of streambank II) were conducted to evaluate variations of N solutes (NO3−, NO2−, and NH4+), N gases (NO, N2O), and the bacterial flora. In both experiments, two treatment solutions containing NO3− (N treatment), and NO3− and S2O32− (N + S treatment) were prepared. In the N + S treatment of the long-term experiment, NO3− concentrations gradually decreased by 98%, with increases in the SO42−, NO2−, NO, and N2O concentrations and with not increase in the NH4+, indicating denitrification had occurred with a high probability. Temporal accumulation of NO2− was observed in the N + S treatment. The stoichiometric ratio of SO42− production and NO3− depletion rates indicated that denitrification using reduced sulfur occurred even without additional S, indicating inherent S also served as an electron donor for denitrification. In the short-term incubation experiment, S addition was significantly decreased NO3− concentrations and increased NO2−, NO, and N2O concentrations, especially in some subsoils with higher sulfide contents. Many denitrifying sulfur-oxidizing bacteria (Thiobacillus denitrificans and Sulfuricella denitrificans) were detected in both streambank I and II, which dominated up to 5% of the entire microbial population, suggesting that these bacteria are widespread in sulfide-rich soil layers in the catchment. We concluded that the catchment with abundant sulfides in the subsoil possessed the potential for sulfur-driven NO3− reduction, which could widely influence N cycling in and NO3− export from the headwater catchment.

scholarly journals Evolutionary rescue of a green alga kept in the dark

2013 ◽  
Vol 9 (1) ◽  
pp. 20120823 ◽  
Author(s):  
Graham Bell
Keyword(s):  
Short Term ◽  
Term Experiment ◽  
Evolutionary Rescue ◽  
Extreme Phenotypes ◽  
Long Term Experiment ◽  
Sexual Histories ◽  
Dark Conditions ◽  
Set Up ◽  
Asexual Populations

Chlamydomonas (Chlorophyta) can grow as a heterotroph on medium supplemented with acetate in the dark. A long-term experiment to investigate adaptation to dark conditions was set up with hundreds of replicate lines. Growth was initially slow, and most lines became extinct when transferred every few weeks. Some lines survived through the expansion of lineages derived from cells with extreme phenotypes and exhibited a U-shaped curve of collapse and recovery. Two short-term experiments were set up to evaluate the effect of sex on the frequency of ‘evolutionary rescue’ by deriving replicate lines from ancestral populations with contrasting sexual histories that had been cultured in the light for hundreds of generations. When transferred to dark conditions of growth, lines derived from obligately sexual populations survived more often than lines derived from facultatively sexual or asexual populations. This reflected the higher initial frequency of cells able to grow in the dark, due to greater genetic diversity supported by sexual fusion and recombination. The greater probability of evolutionary rescue suggests a general reason for the prevalence of sexual species.

scholarly journals Long and short term changes in crop yield and soil properties induced by the reduction of soil tillage in a long term experiment in Switzerland

2017 ◽  
Vol 174 ◽  
pp. 120-129 ◽  
Author(s):  
Lucie Büchi ◽  
Marina Wendling ◽  
Camille Amossé ◽  
Bernard Jeangros ◽  
Sokrat Sinaj ◽  
...  
Keyword(s):  
Soil Properties ◽  
Crop Yield ◽  
Soil Tillage ◽  
Short Term ◽  
Term Experiment ◽  
Long Term Experiment

Within season variability of bicarbonate extractable phosphorus in wheat soils

Soil Research ◽  
1977 ◽  
Vol 15 (2) ◽  
pp. 167 ◽  
Author(s):  
RS Jessop ◽  
B Palmer ◽  
VF Mcclelland ◽  
R Jardine
Keyword(s):  
Environmental Conditions ◽  
Short Term ◽  
Weekly Basis ◽  
Term Experiment ◽  
Agricultural College ◽  
Long Term Experiment ◽  
Extractable Phosphorus ◽  
Over Time

Using a long-term experiment at Longerenong Agricultural College, Dooen, Vic., plots from a pasture-pasture-fallow-wheat rotation were sampled on a three-weekly basis for a year. Analysis of the samples by bicarbonate extraction for phosphorus indicated considerable short-term fluctuations in phosphorus which were only partially explained by environmental conditions. Bicarbonate extractable phosphorus was both lowest and less variable over time under a two-year pasture treatment than when under fallow.

Long / Short Term Experimental Study on Chloride Penetration in Cracked Concrete

2009 ◽  
Vol 417-418 ◽  
pp. 765-768 ◽  
Author(s):  
In Seok Yoon ◽  
Erik Schlangen
Keyword(s):  
Chloride Penetration ◽  
Crack Healing ◽  
Short Term ◽  
Cracked Concrete ◽  
Term Experiment ◽  
Long Term Experiment ◽  
Set Up ◽  
Short Term Experiment ◽  
Penetration Behaviour

This study is focused on examining the effect of cracks on chloride penetration into concrete. In order to get reliable results, short-term and long term experiments were set up and chloride penetration behaviour through cracks was examined. It was noticed that chloride penetration through cracks tends to decrease with time. One of the explanations is crack-healing. Especially, this trend was obvious in concrete samples with larger crack width. However, measuring the border between chloride contaminated zone and healthy zone was clear in concrete of short-term experiment, while it was ambiguous in long term experiment.

scholarly journals P0110DPP4- INHIBITOR LINAGLIPTIN ACCELERATES RESOLUTION OF CRESCENT FORMATION IN A RAT MODEL OF ANTI-GBM GLOMERULONEPHRITIS

2020 ◽  
Vol 35 (Supplement_3) ◽  
Author(s):  
Anna-Lena Mayer ◽  
Nadja Ebert ◽  
Thomas Klein ◽  
Kerstin Amann ◽  
Christoph Daniel
Keyword(s):  
Human Kidney ◽  
Term Treatment ◽  
Fibrosis Score ◽  
Short Term ◽  
Short Term Treatment ◽  
Crescent Formation ◽  
Term Experiment ◽  
Long Term Experiment ◽  
Glomerular Tuft

Abstract Background and Aims Crescent formation is a severe glomerular damage in the pathogenesis of different kidney diseases. However the exact pathomechanism of crescent formation is unclear up to now. In human kidney biopsies we observed high dipeptidyl peptidase 4 (DPP4) expression in early crescent formation. Therefore, we investigated the potential involvement of DPP4 in the pathogenesis of crescentic anti-GBM nephritis in a rat model using a DPP4- inhibitor independent of his present use in the treatment of type 2 diabetes. Method Anti-GBM nephritis was induced in Wistar Kyoto rats for investigation of short and long term effects of the DPP4- inhibitor linagliptin treatment (3 mg/kg bw). In the short term experiment (endpoint 2 weeks) linagliptin treatment was started either with model induction or one week later. In the long term experiment (endpoint 8 weeks) linagliptin treatment was started either on day 0 or on week 4. In both experiments we included an untreated healthy and anti-GBM nephritic group. All groups consisted of 11 animals. Kidney function was monitored on weeks 1, 2, 3, 5 and 8. Kidney tissue was used to determine DPP4 expression and activity, morphologic changes and mRNA expression. Results Similarly to our observation in human kidney biopsies the in situ DPP4 activity and DPP4 expression were both increased in nephritic glomeruli especially within the crescents. Linagliptin could almost completely inhibit all renal DPP4 activity without any effect on DPP4 expression. Short-term treatment had no significant effect on crescent formation. However, long-term preventive treatment resulted in reduced number of crescents (51±3% vs 65±3%), glomerulosclerosis (score 1.2±0.07 vs 1.6±0.1), tubulointerstitial injury (score 1.2±0.1 vs 1.8±0.2), renal fibrosis (score 1.3±0.13 vs 1.9±0.14) and proteinuria (265±29 vs 363±22 mg/24h) compared to untreated nephritic rats. Therapeutic intervention with linagliptin resulted in weaker amelioration of renal disease at week 8, but also significantly reduced renal fibrosis (score 1.4±0.13 vs. 1.9±0.14) and crescent formation (52±4% vs. 65±3%) compared with vehicle. About 20% of all glomeruli showed Pax8+ parietal epithelial cells (PECs) on the tuft in short term treatment, being significantly reduced by therapeutic linagliptin treatment on day 14. In the long term experiment the number of Pax8+ PECs on glomerular tuft was reduced by more than 50% in both treatment groups and confirmed by quantitative mRNA analysis using isolated glomeruli. Despite the number of Pax8-positive cells on glomerular tuft was reduced by linagliptin therapy, a subpopulation of PECs positive for the transcription factor SOX9 was significantly increased on glomerular tuft compared to healthy and non-treated rats on day 14. Conclusion DPP4- inhibition with linagliptin reduced Pax8+ cells on glomerular tuft, indicating accelerated resolution of formed crescents and improvement in renal injury. This DDP4 effect might be mediated by differential regulation of a subpopulation of PECs expressing the transcription factor SOX9.

scholarly journals Effects of NaCl-salinity on growth and inorganic solute accumulation in young cashew plants

2001 ◽  
Vol 5 (2) ◽  
pp. 216-222 ◽  
Author(s):  
Ricardo A. Viégas ◽  
Joaquim A. G. da Silveira ◽  
Adeildo R. de Lima Junior ◽  
José E. Queiroz ◽  
Maria J. M. Fausto
Keyword(s):  
Fresh Mass ◽  
Short Term ◽  
Tissue Concentrations ◽  
Term Experiment ◽  
Whole Plant ◽  
Solute Accumulation ◽  
Long Term Experiment ◽  
Short Term Experiment ◽  
Hydroponically Grown

The NaCl effects on the growth and inorganic solute accumulation were studied on 30-day-old cashew plants (Anacardium occidentale L.) hydroponically grown for 8 days (short term) and 40 days (long-term) with NaCl at different levels. The shoot fresh mass yielded after 40 days, in response to 50 and 100 mol m-3 NaCl, decreased by 25 and 75%, respectively. This decrease was markedly low in root fresh mass, which did not change under 50 mol m-3 NaCl and decreased nearly to 30% under 100 mol m-3 NaCl, as compared to control plants. In short-term experiment, salinity induced only slight changes of K+ tissue concentrations in the whole plant. In the long-term experiment, K+ tissue concentrations were substantially decreased, particularly in roots. In response to time and increasing levels of salinity, Na+ and Cl- ions concentrations reached toxic levels in leaves. Thus, cashew plants already from the 4th day of salinity stress exhibited earlier symptoms of ionic toxicity, and therefore they were not able to regulate metabolic and physiological functions under these harmful conditions.

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