scholarly journals Numerical Model of Fish Exploitation – structure and application

2019 ◽  
Vol 27 (2) ◽  
pp. 86-101
Author(s):  
Paweł Buras ◽  
Wiesław Wiśniewolski
Keyword(s):  
Numerical Model ◽  
Simulation Models ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Recreational Fisheries ◽  
Fisheries Resources ◽  
Fish Exploitation ◽  
The Common ◽  
Common Bream ◽  
The Impact

Abstract Fisheries simulation models are tools used for forecasting the effects of exploitation and determining the directions of managing fisheries resources. The Numerical Model of Fish Exploitation (NMFE) and its capabilities were tested on a population of common bream, Abramis brama (L.) in a dam reservoir that is exploited by commercial and recreational fisheries. Based on the designated population parameters of N0, Fij, Mi, and ei and the size and structure of the common bream population in the reservoir, the model was used to examine hypothetical simulation variants of changes in fishing intensity E1 with nets and rods, changes in fishing intensity based on actual fishing effort with nets, changes in natural mortality, changes in the size of fish caught, and the impact of this on the size of the resources. Initial catches with nets and rods were calculated. Increasing fishing effort did not translate proportionally to increased catches, and the function was curvilinear. The results of simulations that reduced the intensity of fishing with nets and decreased catch sizes concurred with data from actual catches. Simulations of changes in natural mortality had various effects on the size of catches. Reducing parameter M did not impact the level of catches, while increasing parameter M reduced the size of catches significantly.

scholarly journals Effects of spatial heterogeneity in growth and fishing effort on yield-per-recruit models: an application to the US Atlantic sea scallop fishery

2015 ◽  
Vol 73 (4) ◽  
pp. 1062-1073 ◽  
Author(s):  
Samuel B. Truesdell ◽  
Deborah R. Hart ◽  
Yong Chen
Keyword(s):  
Spatial Heterogeneity ◽  
Spatial Data ◽  
Egg Production ◽  
Fishing Effort ◽  
Natural Mortality ◽  
Fishing Mortality ◽  
Sea Scallop ◽  
The Us ◽  
The Impact ◽  
Yield Per Recruit

Abstract Conventional yield-per-recruit (Y/R) and spawning-stock biomass-per-recruit (SSB/R) models make no allowance for spatial heterogeneity in fishing mortality, natural mortality, or growth across the stock area, although variability in these processes can affect model results. For example, areas with higher growth and/or lower natural mortality rates should be fished at a lower rate to maximize Y/R; however, these areas may be especially attractive to fishers and are often fished harder. Here, Y/R and SSB/R models are developed that simultaneously account for spatial heterogeneity in growth and fishing effort. These models are applied to the US Atlantic sea scallop (Placopecten magellanicus) fishery. The spatial variability in growth uses depth-integrated models from the literature and variability in effort is based on, alternatively, uniform, observed, and relative-optimal spatial harvesting distributions. The observed effort patterns are derived from vessel monitoring system positions, and illustrate one application for these widely collected but underutilized spatial data. In this example, the distribution of observed fishing effort reduces Y/R compared with the relative-optimal, or the uniform effort distribution implicitly assumed by conventional Y/R analysis. SSB/R was in some cases considerably higher under the relative-optimal distribution of effort than when calculated using observed or uniform effort patterns. Such more realistic spatially integrated Y/R and SSB/R models can help to evaluate the impact of effort patterns on fishery yield and stock egg production. These models demonstrate that the spatial distribution of effort can be as important as the overall average fishing mortality when managing fisheries to optimize Y/R, SSB/R, and yield.

The impact of applying the Common Customs Tariff on the armenian export of Cut and Polished Gems to Russia

2019 ◽  
pp. 33-41
Author(s):  
V. L. Harutyunyan ◽  
S. V. Dokholyan ◽  
A. R. Makaryan
Keyword(s):  
Manufacturing Sector ◽  
Practical Implication ◽  
Dominant Role ◽  
New Technology ◽  
Manufacturing Companies ◽  
Medium Term ◽  
Diamond Cutting ◽  
Global Trends ◽  
The Common ◽  
The Impact

The presented study discusses the issues of applying the Common Customs Tariff (CCT) rates of the Eurasian Economic Union (EAEU) on rough diamonds and the impact thereof on the exports of stones cut and polished inArmeniaand then exported toRussia.Aim. The study aims to identify the possible strategies Armenian diamond cutting and polishing companies could adopt as a response to the application of the CCT rates on rough diamonds and how it would affect exports to various destinations, namely to Russia.Tasks. The authors analyze the current state of the gems and jewelry sector and substantiate the need to either integrate it into the jewelry manufacturing sector or to apply various strategies to facilitate exports to either Russia or other destinations in the medium term in response to the application of the CCT rates.Methods. This study uses general scientific methods of cognition, including analytical and methodological approaches and elements of forecasting. Possible strategies the Armenian diamond cutting and polishing companies could adopt in the medium term in response to the application of the EAEU CCT rates are determined using the analytical research method, forecasts in the context of the developments in the Armenian gem processing and jewelry market and global trends, statistical data on the imports and exports of cut and polished gems and jewelry for 2014–2018 published by the UN Comtrade Statistics.Results. Statistics on the exports of processed diamonds from 2014 to 2018 highlights the issue associated with the loss of competitiveness suffered by Armenian companies (mainly in comparison with Indian diamond cutters). The major global trends in the diamond cutting and polishing business indicate that it could be virtually impossible for Armenian cutters and polishers to compete with Indian companies in the medium term if they do not comes to investing in new technology to achieve operational efficiency. For these companies, it is important not to lose the Russian market due to an increase in the tariff rate and concentrate on the processing of gems that are larger than 1 carat. Another strategy to avoid an increase in the customs tariff rates would depend on the Armenian government’s ability to negotiate with Russia in respect of direct imports of diamond stones from Russian manufactures. Two other options for Armenian cutters involve focusing on cutting and polishing of rubies, sapphires, emeralds, etc. or integrating into the jewelry sector either by being the primary supplier or by considering this business as a channel to sell processed diamond stones by setting up their own jewelry manufacturing companies.Conclusions. With CCT going into effect in January 2021 and India’s dominant role in the diamond cutting and polishing business, Armenia needs to carefully consider all of the strategies the Armenian companies could adopt, as discussed above. As a member state of the EAEU, Armenia freely exports to Russia, however, further exports to Russia would depend on Armenia’s ability to ensure that cost-effective operations are in place, or to concentrate on the processing of precious gems rather than diamonds, or to switch to the manufacturing of jewelry items as a major export item.Practical Implication. The findings of this study could be of interest to the Ministry of Economy of the Republic of Armenia and Business Armenia that could be used in elaborating the strategy for the development of Armenian gems and jewelry sector of the economy.

The Impact of Applying the Common Customs Tariff on Armenian Exports of Tobacco Products

2020 ◽  
Vol 26 (4) ◽  
pp. 358-365
Author(s):  
V. L. Harutyunyan ◽  
S. V. Dokholyan ◽  
A. R. Makaryan
Keyword(s):  
Tobacco Products ◽  
The Common ◽  
The Impact

Marine Quality Standards: Their Derivation and Application in the United Kingdom

1985 ◽  
Vol 17 (6-7) ◽  
pp. 1187-1198 ◽  
Author(s):  
G. Mance ◽  
A. R. O'Donnell
Keyword(s):  
Coastal Waters ◽  
Sublethal Effects ◽  
Quality Standards ◽  
Toxicity Data ◽  
Marine Life ◽  
Nickel Zinc ◽  
The United Kingdom ◽  
The Common ◽  
Lead Nickel ◽  
The Impact

This paper discusses the derivation of environmental quality standards for coastal waters and the difficulties of using such standards for controlling industrial discharges. Attention is focused on the common List II substances, copper, chromium, lead, nickel, zinc and arsenic - and their effects on marine life. The adequacy of existing toxicity data is discussed and it is concluded that long exposure tests are required to provide information on sublethal effects. Such data are currently limited. It is also important that consideration be given to the effects that reducing salinities and increasing temperatures have in increasing the toxicity of these substances. The complexity of interpreting the results of laboratory toxicity data to coastal waters is discussed with reference to a study of the impact of an industrial discharge.

Larvae of the blow fly Caiusa testacea (Diptera: Calliphoridae) as egg predators of Polypedates cruciger Blyth, 1852 (Amphibia: Anura: Rhacophoridae)

2020 ◽  
Vol 12 (17) ◽  
pp. 17374-17379
Author(s):  
W.G.D. Chathuranga ◽  
K. Kariyawasam ◽  
Anslem De Silva ◽  
W.A.Priyanka P. De Silva
Keyword(s):  
Sri Lanka ◽  
High Impact ◽  
Tree Frog ◽  
Blow Fly ◽  
Breeding Habitats ◽  
The Family ◽  
Water Container ◽  
The Common ◽  
Natural Breeding ◽  
The Impact

We investigated the impact of dipteran predators on eggs in foam nests of the Common Hour-glass Tree Frog Polypedates cruciger Blyth, 1852 (Anura: Rhacophoridae) in central Sri Lanka.  Foam nests (n=24) of P. cruciger were examined at their natural breeding habitats and infected (n=8) and uninfected spawns (n=16) were identified.  Emerging tadpoles were collected in a water container hung under each spawn and the average number of tadpoles (N) hatched from infected spawns (N=0) was compared with that of uninfected spawns (N=354 ± 67).  Three severely infected spawns were brought to the laboratory and the fly larvae were reared until they metamorphosed to adults.  Morphological and molecular identification of the flies confirmed them as belonging to Caiusa testacea Senior-White, 1923 of the family Calliphoridae.  The infected spawns were completely destroyed and an estimated average of 400 P. cruciger eggs per spawn were lost.  The results revealed a high impact of Caiusa testacea on egg and embryo mortality of P. cruciger.

Theory and Method and the Stakes of a Fragmented Discipline: Or, What Economics Taught Me About the Study of Religion

2020 ◽  
Author(s):  
Thomas A Lewis
Keyword(s):  
Religious Studies ◽  
The Public ◽  
Global Pandemic ◽  
Recent Developments ◽  
The Common ◽  
The Impact ◽  
Academic Study

Abstract As a discipline, the academic study of religion is strikingly fragmented, with little engagement or shared criteria of excellence across subfields. Although important recent developments have expanded the traditions and peoples studied as well as the methods used, the current extent of fragmentation limits the impact of this diversification and pluralization. At a moment when the global pandemic is catalyzing profound pressures on our universities and disciplines, this fragmentation makes it difficult to articulate to the public, to non-religious studies colleagues, and to students why the study of religion matters. We therefore too often fall back on platitudes. I argue for a revitalized methods and theories conversation that connects us even as it bears our arguments and disagreements about what we do and how. Courses in methods and theories in the study of religion represent the most viable basis we have for bringing the academic study of religion into the common conversation or argument that constitutes a discipline without sacrificing our pluralism.

scholarly journals A Model for the Thermal Behaviour of an Offshore Cable Installed in a J-Tube

Proceedings ◽  
2020 ◽  
Vol 58 (1) ◽  
pp. 31
Author(s):  
Jeremy Arancio ◽  
Ahmed Ould El Moctar ◽  
Minh Nguyen Tuan ◽  
Faradj Tayat ◽  
Jean-Philippe Roques
Keyword(s):  
Sensitivity Analysis ◽  
Numerical Model ◽  
Thermal Behaviour ◽  
Energy Production ◽  
Power Transmission ◽  
Temperature Fields ◽  
Sobol Indices ◽  
Lumped Element ◽  
Thermal Phenomena ◽  
The Impact

In the race for energy production, supplier companies are concerned by the thermal rating of offshore cables installed in a J-tube, not covered by IEC 60287 standards, and are now looking for solutions to optimize this type of system. This paper presents a numerical model capable of calculating temperature fields of a power transmission cable installed in a J-tube, based on the lumped element method. This model is validated against the existing literature. A sensitivity analysis performed using Sobol indices is then presented in order to understand the impact of the different parameters involved in the heating of the cable. This analysis provides an understanding of the thermal phenomena in the J-tube and paves the way for potential technical and economic solutions to increase the ampacity of offshore cables installed in a J-tube.

scholarly journals Roles of Microglial Ion Channel in Neurodegenerative Diseases

2021 ◽  
Vol 10 (6) ◽  
pp. 1239
Author(s):  
Alexandru Cojocaru ◽  
Emilia Burada ◽  
Adrian-Tudor Bălșeanu ◽  
Alexandru-Florian Deftu ◽  
Bogdan Cătălin ◽  
...  
Keyword(s):  
Ion Channels ◽  
Neurodegenerative Diseases ◽  
Excitable Cells ◽  
Proton Channels ◽  
Voltage Gated ◽  
Cellular Processes ◽  
Pathological Conditions ◽  
The Common ◽  
Transient Receptor ◽  
The Impact

As the average age and life expectancy increases, the incidence of both acute and chronic central nervous system (CNS) pathologies will increase. Understanding mechanisms underlying neuroinflammation as the common feature of any neurodegenerative pathology, we can exploit the pharmacology of cell specific ion channels to improve the outcome of many CNS diseases. As the main cellular player of neuroinflammation, microglia play a central role in this process. Although microglia are considered non-excitable cells, they express a variety of ion channels under both physiological and pathological conditions that seem to be involved in a plethora of cellular processes. Here, we discuss the impact of modulating microglia voltage-gated, potential transient receptor, chloride and proton channels on microglial proliferation, migration, and phagocytosis in neurodegenerative diseases.

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