scholarly journals The Role of Harvesting in Population Control in Presence of Multiple Stochastic Noise Sources

2021 ◽  
Author(s):  
Saroj Kumar Mandal ◽  
Dipak Kumar Jana ◽  
Swarup Poria
Keyword(s):  
Stochastic Control ◽  
Population Control ◽  
Marine Ecosystem ◽  
Single Species ◽  
Stochastic Bifurcation ◽  
Deterministic Case ◽  
Steady State Probability ◽  
Constant Rate ◽  
Stochastic Case

Abstract In this paper, we compare the role of constant and Michaelis-Menten type harvesting in single species population control in presence of stochastic noises sources. Steady state probability distributions and stationary potentials of the population for the two types of harvesting are determined by Fokker-Planck equations. Stochastic bifurcation analysis and mean first passage times have been computed. Noise induced critical transitions are observed depending on the strength of the noises. The extinction possibility of population in stochastic control with Michaelis-Menten type harvesting is higher than the constant rate of harvesting. One of the findings is the transition of the population from bistable to tristable for weak noise and Michaelis-Menten type harvesting. Another finding is noise enhanced stability phenomenon for negatively correlated noises. In case of population control, constant rate of harvesting is better in deterministic case whereas Michaelis-Menten type harvesting is better in stochastic case. The stochastic control is more efficient than deterministic control as average population size in stochastic case is lower than the deterministic case. The results obtained in this study can throw light on toxic phytoplankton blooms and its control in marine ecosystem. Moreover, the study can be useful to explain wild prey population outbreak and its control in deep forest.

Population Control (Review Article)

1961 ◽  
Vol 1 (3) ◽  
pp. 89-98
Author(s):  
Karol J. Krotki
Keyword(s):  
Population Control ◽  
Review Article ◽  
Small Enterprise ◽  
Opportunity Costs ◽  
Relative Importance ◽  
Factual Information ◽  
Undue Influence ◽  
Clear Cut ◽  
Economic Considerations

Discussions about the role of small enterprise in economic development tend to remain inconclusive partly because of the difficulty of assessing the relative importance of economic and non-economic objectives and partly because of the dearth of factual information on which to base an economic calculus. It is probably true, moreover, that, because of a lack of general agreement as to the economic case for or against small enterprise, non-economic considerations, including some merely romantic attitudes toward smallness and bigness, tend to exert an undue influence on public policies. There may, of course, be no clear-cut economic case. And noneconomic considerations should and will inevitably weigh significantly in policy decisions. If, however, some of the economic questions could be settled by more and better knowledge, these decisions could more accurately reflect the opportunity costs of pursuing non-economic objectives.

scholarly journals The Effect of Perioperative Administration of Probiotics on Colorectal Cancer Surgery Outcomes

Nutrients ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1451
Author(s):  
Louise Pitsillides ◽  
Gianluca Pellino ◽  
Paris Tekkis ◽  
Christos Kontovounisios
Keyword(s):  
Colorectal Cancer ◽  
Perioperative Management ◽  
Single Species ◽  
Infectious Complications ◽  
Mucosal Permeability ◽  
Colorectal Cancer Surgery ◽  
Rate Analysis ◽  
Surgery Outcomes ◽  
Randomised Controlled

The perioperative care of colorectal cancer (CRC) patients includes antibiotics. Although antibiotics do provide a certain protection against infections, they do not eliminate them completely, and they do carry risks of microbial resistance and disruption of the microbiome. Probiotics can maintain the microbiome’s balance postoperatively by maintaining intestinal mucosal integrity and reducing bacterial translocation (BT). This review aims to assess the role of probiotics in the perioperative management of CRC patients. The outcomes were categorised into: postoperative infectious and non-infectious complications, BT rate analysis, and intestinal permeability assessment. Fifteen randomised controlled trials (RCTs) were included. There was a trend towards lower rates of postoperative infectious and non-infectious complications with probiotics versus placebo. Probiotics reduced BT, maintained intestinal mucosal permeability, and provided a better balance of beneficial to pathogenic microorganisms. Heterogeneity among RCTs was high. Factors that influence the effect of probiotics include the species used, using a combination vs. single species, the duration of administration, and the location of the bowel resection. Although this review provided evidence for how probiotics possibly operate and reported notable evidence that probiotics can lower rates of infections, heterogeneity was observed. In order to corroborate the findings, future RCTs should keep the aforementioned factors constant.

Regulation of free fatty acid metabolism by insulin in humans: role of lipolysis and reesterification

2006 ◽  
Vol 263 (6) ◽  
pp. E1063-E1069 ◽  
Author(s):  
P. J. Campbell ◽  
M. G. Carlson ◽  
J. O. Hill ◽  
N. Nurjhan
Keyword(s):  
Fatty Acid ◽  
Free Fatty Acid ◽  
Acid Metabolism ◽  
Insulin Dose ◽  
Healthy Humans ◽  
Constant Rate ◽  
Free Fatty Acid Metabolism ◽  
Plasma Ffa ◽  
Maximal Suppression

The regulation of lipolysis, free fatty acid appearance into plasma (FFA R(a)), an FFA reesterification and oxidation were examined in seven healthy humans infused intravenously with insulin at rates of 4, 8, 25, and 400 mU.m-2.min-1. Glycerol and FFA R(a) were determined by isotope dilution methods, and FFA oxidation was calculated by indirect calorimetry or by measurement of expired 14CO2 from infused [1-14C]palmitate. These measurements were used to calculate total FFA reesterification, primary FFA reesterification occurring within the adipocyte, and secondary reesterification of circulating FFA molecules. Lipolysis, FFA R(a), and secondary FFA reesterification were exquisitely insulin sensitive [the insulin concentrations that produced half-maximal suppression (EC50), 106 +/- 26, 91 +/- 20 vs. 80 +/- 16 pM, P = not significant] in contrast to insulin suppression of FFA oxidation (EC50, 324 +/- 60, all P < 0.01). The absolute rate of primary FFA reesterification was not affected by the increase in insulin concentration, but the proportion of FFA molecules undergoing primary reesterification doubled over the physiological portion of the insulin dose-response curve (from 0.23 +/- 0.06 to 0.44 +/- 0.07, P < 0.05). This served to magnify insulin suppression of FFA R(a) twofold. In conclusion, insulin regulates FFA R(a) by inhibition of lipolysis while maintaining a constant rate of primary FFA reesterification.

scholarly journals Plankton blooms in vortices: the role of biological and hydrodynamic timescales

2007 ◽  
Vol 14 (4) ◽  
pp. 443-454 ◽  
Author(s):  
M. Sandulescu ◽  
C. López ◽  
E. Hernández-García ◽  
U. Feudel
Keyword(s):  
Coastal Upwelling ◽  
Marine Ecosystem ◽  
Coupled System ◽  
Component Model ◽  
Residence Times ◽  
Key Factors ◽  
Mesoscale Structures

Abstract. We study the interplay of hydrodynamic mesoscale structures and the growth of plankton in the wake of an island, and its interaction with a coastal upwelling. Our focus is on a mechanism for the emergence of localized plankton blooms in vortices. Using a coupled system of a kinematic flow mimicking the mesoscale structures behind the island and a simple three component model for the marine ecosystem, we show that the long residence times of nutrients and plankton in the vicinity of the island and the confinement of plankton within vortices are key factors for the appearance of localized plankton blooms.

scholarly journals Role of non-traditional fodder crops in fodder production of upper Volga and the scientific basis for their cultivation in single-species and mixed sowing

2019 ◽  
Vol 2019 (2) ◽  
pp. 6-16 ◽  
Author(s):  
Сабир Эседуллаев ◽  
Sabir Esedullaev ◽  
Наталья Шмелева ◽  
Natalia Shmeleva
Keyword(s):  
Mineral Nutrition ◽  
Single Species ◽  
Scientific Basis ◽  
Forage Crops ◽  
Protein Ratio ◽  
Fodder Production ◽  
Fodder Crops ◽  
Crop Root ◽  
The Comparative Study

The results of many years of research on the comparative study of single-species and mixed crops of non-traditional forage crops, including festulolium used to create a sustainable forage base balanced in energy, protein and carbohydrates, are presented. The scientific basis for the cultivation of herbs in single and mixed sowing has been determined. It was established that the yield of green mass of festulolium is high-er than that of traditional cereal grasses and on control for an average of three years amounted to 19.8 t/ha, against the background of mineral nutrition — 29.9 t/ha. In mixed sowings, grass mixtures consisting of clover and festulolium and alfalfa and festulolium were distinguished in terms of productivi-ty and fodder value. They provided the harvest of fodder units of 7.95 and 8.65 thousand/ha, with the provision of the fodder unit with digestible protein at the level of the norm or much higher than it — 101–134 g, with an optimal (0.8–1.0) sugar-protein ratio on both backgrounds. The positive effect of grasses on soil fertility, expressed in the accumulation of a significant amount of crop-root residues and nitrogen, is shown. Single-species crops of clover and alfalfa have accumulated 9.83 and 14.8 t/ha of crop-root re-sidues at the control and 10.8 and 19.5 t/ha against the background of mineral nutrition, with which 154, 328 and 253, 431 kg, respectively, were supplied with nitrogen ha, of which symbiotic – 65, 140 and 85, 183 kg/ha.

scholarly journals Ecological interrelations of Rapana venosa (Gastropoda: Muricidae) with ichthyofauna in the Black Sea

2016 ◽  
Vol 1 (4) ◽  
pp. 76-77
Author(s):  
I. P. Bondarev
Keyword(s):  
Black Sea ◽  
Marine Ecosystem ◽  
Fish Fauna ◽  
The Black Sea ◽  
Sandy Bottom ◽  
Rapana Venosa ◽  
New Information ◽  
Bottom Zone

Systematic monitoring of ecologically significant species – predatory mollusc Rapana venosa Valenciennes, 1846 populations – is an important part of the Black Sea monitoring. The study of the role of R. venosa in contemporary marine ecosystem is of considerable interest. In June-September 2015-2016 the study of consorting relations of rapana was conducted in situ with a parallel sampling by diver. In the course of research new information about the interaction of R. venosa with the fish fauna has been obtained. Of particular importance for fishes is the presence of rapana in the sandy bottom zone, where there are no natural shelters, and food resources are limited. The most important for the fish is the presence on the rapana shells of algal fouling and epiphyton. The shells of invader – R. venosa – and its fouling create additional opportunities for the survival of some fish fauna representatives juveniles of the Black Sea. The data obtained extend the concepts of ecological role of mollusc – invader R. venosa, as well as the ecology and ethology of several fish species.

scholarly journals Local Governance Collaboration Model For Preserving Marine Ecosystem In The Coastal Area of Nusa Lembongan Island, Klungkung Regency, Bali

2019 ◽  
pp. 210
Author(s):  
Ida Ayu Putu Sri Widnyani ◽  
I Made Kusna Antara ◽  
Nyoman Diah Utari Dewi
Keyword(s):  
Local Governance ◽  
Local Level ◽  
Marine Ecosystem ◽  
Mangrove Forests ◽  
Local Policy ◽  
Tourist Attractions ◽  
Collaboration Model ◽  
Qualitative Descriptive ◽  
Traditional Institutions

The marine ecosystem on the coast of Nusa Lembongan is one of the tourist attractions such as coral reefs, mangrove forests and others. The high number of tourist visiting the island also impacts tourism facilities. Increased tourism also has the opportunity to damage the marine ecosystem. Therefore needs a collaboration among stakeholders in maintaining the sustainability of the marine ecosystem                . The purpose of this research is to find out and analyze also to find a collaborative model of stakeholders such as government, private sector, community and traditional institutions in preserving the marine ecosystem in Nusa Lembongan. The research is using a qualitative descriptive approach with determining informants technic is purposive sampling. Local government collaboration model in conserving marine ecosystems by strengthening the role of stakeholders at the local level such as: 1) signing memorandum of understanding for creating regional regulations as a policy of the Klungkung Regency; 2) writing in to a local wisdom (awig-awig) as a local policy of the local wisdom institutions (adat); 3) writing into the policy of the tour operator; 4) implement the Tri Hita Karana concept and creating a memorandum of understanding for all parties.

Marine ecosystem assessment in a fisheries management context

2002 ◽  
Vol 59 (9) ◽  
pp. 1429-1440 ◽  
Author(s):  
Jason S Link ◽  
Jon K.T Brodziak ◽  
Steve F Edwards ◽  
William J Overholtz ◽  
David Mountain ◽  
...  
Keyword(s):  
Fisheries Management ◽  
Marine Ecosystem ◽  
Single Species ◽  
Reference Points ◽  
System Level ◽  
Multivariate Statistical Methods ◽  
Multivariate Statistical ◽  
Management Context ◽  
Ecosystem Level ◽  
Ecosystem Based Fisheries Management

We examined a suite of abiotic, biotic, and human metrics for the northeast U.S. continental shelf ecosystem at the aggregate, community, and system level (>30 different metrics) over three decades. Our primary goals were to describe ecosystem status, to improve understanding of the relationships between key ecosystem processes, and to evaluate potential reference points for ecosystem-based fisheries management (EBFM). To this end, empirical indicators of ecosystem status were examined and standard multivariate statistical methods were applied to describe changes in the system. We found that (i) a suite of metrics is required to accurately characterize ecosystem status and, conversely, that focusing on a few metrics may be misleading; (ii) assessment of ecosystem status is feasible for marine ecosystems; (iii) multivariate points of reference can be determined for EBFM; and (iv) the concept of reference directions could provide an ecosystem level analog to single-species reference points.

Role of cardiac lymph and interstitial fluid in lipid metabolism of canine heart

1978 ◽  
Vol 56 (6) ◽  
pp. 1041-1046 ◽  
Author(s):  
Pierre Julien ◽  
Gilles R. Dagenais ◽  
Laimonis Gailis ◽  
Paul-E. Roy
Keyword(s):  
Fatty Acids ◽  
Femoral Vein ◽  
Canine Heart ◽  
Triglyceride Fraction ◽  
Constant Rate ◽  
Arterial Concentration ◽  
Anesthetized Dogs ◽  
Arterial Plasma ◽  
The Relationship

To determine whether cardiac interstitial spaces participate in cardiac fatty acid pool, the relationship between cardiac lymph and arterial plasma free palmitate and triglycerides was studied in anesthetized dogs. [14C]Sucrose, infused at a constant rate in a femoral vein, appeared in the lymph at 90% of its arterial concentration within 60 min. On the other hand, when [1-14C]palmitate was infused at the same rate and at the same site, the ratio of lymph to arterial plasma 14C-labelled free fatty acids (FFA) was only 21% at 60 min and 25% at 120 min, even though the concentrations of endogenous FFA in lymph and arterial plasma were the same. The ratio reached 90% only 24 h after a bolus injection of [3H]palmitate. [1-14C]Palmitate in the lymph triglyceride fraction was only 8% of that in plasma. Although the lymph composition may be influenced by the metabolism of heart muscle, cardiac adipose tissue, and serum lipoproteins, these results indicate the presence of a pool of myocardial fatty acids which may be partly located in the interstitial spaces.

Some clues as to the formation of protrusions by Fundulus deep cells

1977 ◽  
Vol 26 (1) ◽  
pp. 139-150
Author(s):  
C. Tickle ◽  
J.P. Trinkaus
Keyword(s):  
Cell Surface ◽  
Negative Pressure ◽  
Surface Flow ◽  
Contractile Properties ◽  
Cell Locomotion ◽  
Local Phenomenon ◽  
Constant Rate

One of the ways in which Fundulus deep cells move in vivo is by putting out long, fingerlike protrusions. This involves a change in the shape of the cell as a whole, with cytoplasmic flow, and is not just a local phenomenon. Moreover, particles on the cell surface move toward a protrusion as it is forming, suggesting surface flow. The role of surface flow is discussed both on a grown level and in respect to molecular fluidity. Long, stable protrusions can be pulled from cells by the application of negative pressure at a constant rate and these behave in a similar way to those formed during cell locomotion. Such long protrusions must be structured. The importance of contractile properties of the cytoplasm in the formation of protrusions was studied by treating cells with media that modify cellular contractility.

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