scholarly journals Does Addition of Perch Larvae as Prey Affect the Growth, Development and Cannibalism Rate of Pikeperch Larvae?

Fishes ◽  
2019 ◽  
Vol 4 (1) ◽  
pp. 21 ◽  
Author(s):  
Aurore Cortay ◽  
Tatiana Colchen ◽  
Pascal Fontaine ◽  
Alain Pasquet
Keyword(s):  
Group Structure ◽  
Stocking Density ◽  
Perca Fluviatilis ◽  
Experimental Conditions ◽  
Live Prey ◽  
Cultured Fish ◽  
Cannibalism Rate ◽  
Two Parameters ◽  
Size Heterogeneity ◽  
Group Structures

Cannibalism occurs in many cultured fish species, especially at the larval and juvenile stages of piscivorous taxa. In farmed percid species, such as pikeperch (Sander lucioperca), intra-cohort cannibalism is a major issue inducing significant losses of the initial stocking density during the first weeks of rearing. Therefore, the present study was designed to investigate the effects of perch larvae (Perca fluviatilis) as live prey on growth, survival and cannibalism in pikeperch larvae under experimental conditions. Additionally, zootechnical and behavioural variables linked to aggressiveness (S postures, attacks, bites and ingestion), and group structures were considered. The survival rate was not different between the two groups (72% with prey vs. 69% without prey), but the cannibalism rate was higher in the group with the prey (28% vs. 10%). The means of final weight and length of pikeperch larvae were higher in the group fed with perch larvae, but size heterogeneity measured by the coefficients of variation for these two parameters did not differ. The specific growth rate was higher in the group fed with perch larvae, but there was no difference between the two groups concerning Fulton’s condition factor. Among all the behavioural variables (aggressiveness, group structure), none differed between the two groups.

scholarly journals Reaction of Ion Exchange Resins with Fenton’s Reagent

Environments ◽  
2018 ◽  
Vol 5 (11) ◽  
pp. 123 ◽  
Author(s):  
Leandro de Araujo ◽  
Júlio Marumo
Keyword(s):  
Ion Exchange ◽  
Catalyst Concentration ◽  
Setting Time ◽  
Ion Exchange Resins ◽  
Experimental Conditions ◽  
Final Volume ◽  
Different Temperatures ◽  
Axial Compressive Strength ◽  
Exchange Resins ◽  
Two Parameters

One of the most common treatment methods for spent ion exchange resins is their immobilization in cement, which reduces the release of radionuclides into the environment. Although this method is efficient, it considerably increases the final volume of the waste due to its low incorporation capacity. This work aims to evaluate the degradation of ion exchange resins by the Fenton process (H2O2/Fe2+). The resin evaluated was a mixture of cationic and anionic resins, both non-radioactive. The reactions were conducted by varying the catalyst concentration (25, 50, 100, and 150 mmol L−1) and the volume of hydrogen peroxide. Three different temperatures were evaluated by varying the flow of reactants, which were 50, 60, and 70 °C. Cement specimens were prepared from the treated solutions and two parameters were assessed—namely, final setting time and axial compressive strength. The results showed that the experimental conditions were suitable to dissolve the resins, and the Fe3+ produced as precipitate during the experiments increased the resistance of the final product. The immobilized product complied with the limits established by regulation.

scholarly journals Educating Anglicans: A case study investigating group work in the Church of England

2014 ◽  
Vol 48 (1) ◽  
Author(s):  
Roger Grainger
Keyword(s):  
Group Work ◽  
Church Of England ◽  
Group Structure ◽  
Dominant Role ◽  
Dominant Form ◽  
The North ◽  
Actual Learning ◽  
Group Structures ◽  
The Church

The dominant form of group work in the Church of England is educational and directive. An investigation was carried out to determine whether other forms of group work could be valuable for the Church in addition to this approach. The same group of nine members, members of two Church of England parishes in the North of England, were involved in 12 sessions of group work, four sessions of each of the three types of group structure, in order for them to report their individual reactions to each type. An Interpretive Phenomenological Analysis (IPA) showed that all three kinds of groups drew attention to four principle areas of comment. In all these kinds of groups, belonging, safety, enrichment and personalvalidation, with each one of the three groups scoring more highly than the other two on one or other of these dimensions. No group showed itself as more directly educational than the others, showing that, for church educational purposes, a range of group structures maybe used as actual learning comes from the experience of group membership itself. Using the qualitative research model of IPA, an investigation was carried out into the principal themes emerging from members’ self-reports concerning their experiences of the three different group structures, revealing four value constructs – belonging or alienation, safety or danger, enrichment or impoverishment and validation or rejection – which played a dominant role in all three kinds of groups. Taken together, each of the three group structures gave a different degree of prominence to each of the four evaluative constructs so that each of the three was shown to be particularly relevant for, and associated with, a particular area of experiential learning.Die onderrig van Anglikane – ’n ondersoek na groepwerk in die Kerk van Engeland: ’n gevallestudie. Die belangrikste vorm van groepwerk in die Kerk van Engeland is opvoedkundig en rigtinggewend van aard. ’n Ondersoek is gedoen na die waarde van bykomende metodes van groepwerk. Dieselfde groep van nege lede uit twee gemeentes in die Noorde van Engeland, was by die 12 groepwerksessies betrokke – vier sessies vir elk van die drie tipes groepstrukture – om hulle in staat te stel om hulle onderskeie reaksies op elkeen van die tipes groepstrukture te rapporteer. ’n Interpretiewe fenomenologiese analise het aangetoon dat al drie tipes groepstrukture die soeklig op vier hoofkenmerke laat val het, naamlik om te behoort, veiligheid, verryking en bevestigingvan eiewaarde. By elke groep het een of meer van hierdie kenmerke swaarder geweeg as by die ander twee groepe. Geeneen van die groepe het opvoedkundig meer as die ander uitgestaan nie, wat bewys dat ’n reeks groepstrukture vir kerklike opvoedkundige doeleindes gebruik kan word, aangesien leer in wese uit die ervaring van die groeplede self kom. Met behulp van die kwalitatiewe navorsingsmodel van die interpretiewe fenomenologiese analise is ondersoek ingestel na die hooftemas soos blyk uit die lede se individuele verslae ten opsigte van hulle ervaring van die drie verskillende groepstrukture. Die verslae het vier waardekonsepte openbaar wat ’n dominante rol in al drie tipes groepe gespeel het, naamlik om te behoort of te vervreem, veiligheid of gevaar, verryking of verarming, en bevestiging van eiewaarde of verwerping. Samevattend blyk dat die drie groepstrukture elkeen ’n ander graad van prominensie aan die vier verskillende waardekonsepte toeken sodat elke groep spesifiek relevant is vir en geassosieer word met ’n spesifieke area van ervaringsleer.

Quasi-linear Cycle Sets and the Retraction Problem for Set-theoretic Solutions of the Quantum Yang-Baxter Equation

2016 ◽  
Vol 23 (01) ◽  
pp. 149-166 ◽  
Author(s):  
Wolfgang Rump
Keyword(s):  
Abelian Group ◽  
Algebraic System ◽  
Binary Operation ◽  
Group Structure ◽  
Baxter Equation ◽  
Proper Extension ◽  
Group Structures ◽  
New Evidence

Cycle sets were introduced to reduce non-degenerate unitary Yang-Baxter maps to an algebraic system with a single binary operation. Every finite cycle set extends uniquely to a finite cycle set with a compatible abelian group structure. Etingof et al. introduced affine Yang-Baxter maps. These are equivalent to cycle sets with a specific abelian group structure. Abelian group structures have also been essential to get partial results for the still unsolved retraction problem. We introduce two new classes of cycle sets with an underlying abelian group structure and show that they can be transformed into each other while keeping the group structure fixed. This leads to a proper extension of the retractibility conjecture and new evidence for its truth.

Analysis of Major Group Structures Used for Nuclear Reactor Simulations

2018 ◽  
Author(s):  
Marco Di Filippo ◽  
Jiri Krepel ◽  
Konstantin Mikityuk ◽  
Horst-Michael Prasser
Keyword(s):  
Cross Sections ◽  
Nuclear Reactor ◽  
Group Structure ◽  
Major Group ◽  
Computational Time ◽  
Sensitivity Threshold ◽  
Energy Structure ◽  
Reactor Spectrum ◽  
Group Structures ◽  
The Impact

Nuclear reactor simulation is often based on multi-group cross-section libraries. The structure and resolution of these libraries have a strong influence on the accuracy and computational time; hence, number of groups and energy structure must be carefully considered. The relationship between group structures and how they impact generated cross-sections can be a critical parameter. Common energy boundaries shared among major group structures were identified and the relative kinship among those was reconstructed in an effort to build a family tree of major group structures. Stochastic code Serpent2 [1] was employed to generate cross-sections of selected isotopes at different reactor compositions and conditions, using the investigated energy group structures. The impact on their generation was quantified by spectral weighted deviation. The 35 major energy structures were divided into three basic families. The key parameters distinguishing them were their applicability to thermal or fast reactors and their applicability in neutronic or multiphysics investigations. A sensitivity threshold of the generated cross-sections over the group structure resolution was investigated. The aim was to identify a group structure with very low dependency on the actual reactor spectrum.

Application of experimental research methodology to the study of nitrification in mixed culture

1996 ◽  
Vol 34 (1-2) ◽  
pp. 245-252 ◽  
Author(s):  
M. Mauret ◽  
E. Paul ◽  
E. Puech-Costes ◽  
M. T. Maurette ◽  
P. Baptiste
Keyword(s):  
Experimental Research ◽  
Research Methodology ◽  
Ammonia Concentration ◽  
Ammonia Removal ◽  
Nitrite Accumulation ◽  
Experimental Conditions ◽  
Specific Effects ◽  
Consecutive Reactions ◽  
Two Parameters ◽  
Positive Effect

Nitrification is an aerobic process formed by two consecutive reactions: nitritation and nitratation. Using an experimental research methodology, we have studied the specific effects and the possible interactions between initial ammonia concentration, pH and temperature on these two reactions as well as on the experimental conditions leading to a nitrite build-up. In the experimental field studied (35 < [N-NH4+]O mg.l−1 < 90, 15 < T°C < 25 and 7 < pH < 8.5), the statistic interpretation of the results shows that only temperature and pH have a significant positive effect on ammonia removal. Moreover, the effect of these two parameters is linear. As for nitrite accumulation, the temperature effect is negligible and a strong interaction between [N-NH4]O and pH is revealed. When the values of these two variables are high, nitratation is inhibited and 50% of the nitrogen introduced at the beginning accumulates temporarily in the form of nitrites. The results clearly show that a high NH3 concentration inhibits Nitrobacter, starting from between 6.6 and 8.9 mg N-NH3.l−1. This research enables a better understanding of the nitrite build-up phenomena which can be thus minimized or maximized in the case of new process of nitrogen treatment.

The Basis For A Neurobiological-Associative Model of Personality and Group Cohesion: The Evolutionary And System Biological Origins Of Social Exclusion, Hierarchy, and Structure

2020 ◽  
Author(s):  
Michael Thomas
Keyword(s):  
Social Interaction ◽  
Social Exclusion ◽  
Feedback Loop ◽  
Group Structure ◽  
Social Systems ◽  
Group Cohesiveness ◽  
Associative Model ◽  
Environmental Conditioning ◽  
The Social ◽  
Group Structures

By using a systems biological perspective and available literature on human social interaction, grouping, and cohesiveness, a new coherent model is proposed that integrates existing social integration and neurobiological research into a theoretical neurobiological framework of personality and social interaction. This model allows for the coherent analysis of complex social systems and interactions within them, and proposes a framework for estimating group cohesiveness and evaluating group structures in order to build and organize optimized social groups. This „Neurobiological-Associative“ model proposes two primary feedback loops, with environmental conditioning (learning) being sorted into an associative model that modulates interaction with the social environment, and which impacts the second feedback loop involving the individuals' neurobiological capacity. In this paper, the concept of neurobiological capacity is developed and based upon contemporary research on intelligence, personality, and social behavior with a focus on the oxytocin, serotonin, and dopamine systems. The basis of social exclusion and group structure is thus, expressed in the very most simple terms, neurobiological compatibility and risk assessment modulated by an internal associative model.

A NEW MODEL OF THE LEARNING PROCESS FOR INNOVATION TEAMS: NETWORKED NOMINAL PAIRS

2009 ◽  
Vol 13 (04) ◽  
pp. 521-535 ◽  
Author(s):  
ROBERT DEW ◽  
GREG HEARN
Keyword(s):  
Group Structure ◽  
Past Research ◽  
Structural Type ◽  
Nominal Group ◽  
Management Approach ◽  
Business Managers ◽  
Significant Difference ◽  
Nominal Groups ◽  
Innovation Teams ◽  
Group Structures

This paper examines how to structure resource-constrained innovation teams in order to maximise learning and creativity within organisations. Past research suggest that nominal groups (based on independent operations by individuals) outperform interactive groups. The results of this study suggest hybrid group structures based on independent operating pairs can be as effective as nominal groups. The study segmented 672 business managers and university post-graduate students into nominal, hybrid and interactive groups of six members. Three groups (one of each structural type) were pitted against each other to solve 4 related puzzles as quickly as possible. The results of these 28 problem-solving task races were aggregated to determine which group structure was most productive. Overall, the results confirmed that nominal groups of six significantly outperform interactive groups of the same size. More importantly, however, the results showed no significant difference between the productivity of nominal groups of six and hybrid groups comprised of three interactive pairs, where each pair operated separately to complete the same puzzle in parallel with the rest of the group. This suggests that structuring innovation teams into networked, nominal pairs may be just as productive as purely nominal group structures. This significantly extends the existing research on nominal groups versus interactive groups as it suggests that completely eliminating interactivity is not the optimal management approach.

scholarly journals Some Spawning Performance Parameters of Cultured Nile Tilapia Oreochromis niloticus, under Brackish Water

2018 ◽  
Vol 7 (1) ◽  
pp. 8
Author(s):  
Nassrin Mashaii ◽  
Farhad Rajabipour ◽  
Mohamad Jafari ◽  
Mohammad Mohammadi ◽  
Habib Sarsangi ◽  
...  
Keyword(s):  
Sex Ratio ◽  
Oreochromis Niloticus ◽  
Stocking Density ◽  
Water Salinity ◽  
Performance Parameters ◽  
Nile Tilapia Oreochromis Niloticus ◽  
Cultured Fish ◽  
The World ◽  
Egg Diameter ◽  
The Impact

Tilapia is one of the most important cultured fish in the world. However, the gap between seed supplies and farmers' demand is one of the serious limitations for tilapia culturists. Notice about different effective agents on tilapia reproduction might be useful for increasing of production and better management of tilapia hatcheries. In the present study, higher efficiency of tilapia Oreochromis niloticus hatchery was considered based on the impact of sex ratio, stocking density, photoperiod, water salinity and replacement period on spawning performance. Sex ratios 1:1, 1:4 and 1:7 (Male: Female), stocking densities 2, 3.5 and 5 fish/m3, photoperiods 6:18, 12:12 and 18:6 (Light:Dark), water salinities  12, 8, 4 and 0 ppt, also10 and 15 days replacement of breeders were studied. Fecundity,breeder and egg per day,spawning intervals, egg diameter and weight were investigated. Results showed stocking density 5 fish/m3, photoperiod 12:12, 8 ppt water salinity and 10 days replacement had better performance. Sex ratio treatments had similar performance.

ACCUMULATION OF HEAVY METALS (CU, ZN, NI, CR, PB, CD) IN TISSUES OF PERCH (PERCA FLUVIATILIS L.) AND ROACH RUTILUS RUTILUS (L.) UNDER EXPERIMENTAL CONDITIONS/SUNKIŲJŲ METALŲ (CU, ZN, NI, CR, PB, CD) KAUPIMASIS EŠERIO PERCA FLUVIATILIS L. IR KUOJOS RUTILUS АККУМУЛЯЦИЯ ТЯЖЕЛЫХ МЕТАЛЛОВ (CU, ZN, NI, CR, PB, CD) В ТКАНЯХ ОКУНЯ PERCA FLUVIATILIS L. И ПЛОТВЫ RUTILLUS RUTILLUS L. В ЭКСПЕРИМЕНТАЛЬНЫХ УСЛОВИЯХ

2008 ◽  
Vol 16 (4) ◽  
pp. 205-212 ◽  
Author(s):  
Raimondas Leopoldas Idzelis ◽  
Vytautas Kesminas ◽  
Gintaras Svecevičius ◽  
Vaidas Misius
Keyword(s):  
Heavy Metals ◽  
Good Condition ◽  
Perca Fluviatilis ◽  
Rutilus Rutilus ◽  
Ecological Monitoring ◽  
Point Of View ◽  
Experimental Conditions ◽  
Roach Rutilus Rutilus ◽  
Perch Perca Fluviatilis

The paper analyses the effects of heavy metals on freshwater fishes. From the point of view of pollution caused by heavy metals, the condition of ecosystems in Lithuania is yet less affected by heavy metals compared to that the world over. Fishes accumulate heavy metals selectively. Fishes mostly accumulate Pb, Cr, Cd. Our experiments showed that MPC (Maximum Permitted Concentration) (0.2 mg/kg) of lead was exceeded 1.6 time in the muscles of perch, and 1.4 time ‐ in the muscles of roach. The MPC (0.05 mg/kg) of cadmium was exceeded 1.2 time in the muscles of perch and roach. It was determined that perch accumulate heavy metals more intensively than roach. Heavy metals accumulate in fishes: liver > muscle> gills. As heavy metals are considered to be one of the most harmful water pollutants, there is a great need for a constant ecological monitoring and reduction of their amounts released into the environment. According to long‐term research data, the MPC in fishes is exceeded only slightly. This confirms a good condition of aquatic ecosystems in Lithuania. Santrauka Įvertintas sunkiųjų metalų pasiskirstymas gėlavandenių žuvų audiniuose monitoringiniuose vandens telkiniuose, taip pat ir kuojų bei ešerių, paveiktų sunkiųjų metalų didžiausiomis leidžiamosiomis koncentracijomis (DLK), audiniuose. Eksperimentiniai tyrimai atlikti su Cu, Zn, Ni, Cr, Pb, Cd, kurių kiekvienas pasižymi kancerogeniniu mutageniniu poveikiu. Nustatyta, kad švino DLK (0,2 mg/kg) buvo viršyta ešerių raumenyse 1,6 karto, o kuojų – 1,4 karto. Kadmio DLK (0,05 mg/kg) ešerių ir kuojų raumenyse buvo viršyta apie 1,2 karto. Taip pat nustatyta, kad ešeriai sunkiuosius metalus kaupia intensyviau nei kuojos. Eksperimentiniai duomenys sutampa su sunkiųjų metalų tyrimų monitoringiniuose vandens telkiniuose duomenimis. Žuvų audiniuose Pb ir Cd koncentracijos yra didžiausios ir dažnai viršija Lietuvos higienos normoje nurodytąją DLK. Tokie rezultatai įpareigoja nuolat kontroliuoti sunkiųjų metalų kiekį žuvyse. Rezultatai pateikiami sunkiųjų metalų sklaidos pasiskirstymo grafikuose. Резюме Представлены данные по распределению тяжелых металлов в тканях пресноводных рыб в мониторинговых водоемах, а также результаты, полученные путем воздействия тяжелых металлов в предельно допустимых концентрациях (ПДК) на окуня и плотву. В экспериментальных исследованиях применялись металлы Cu, Zn, Ni, Cr, Pb, Cd, оказывающие на живые организмы воздействие мутагенного и канцерогенного характера. Установлено, что концентрация Cd в тканях окуня превышала ПДК (0,2 мг/кг) в 1,6 раза, а в тканях плотвы – в 1,4 раза. Концентрация Cd в тканях тех же рыб превышала ПДК (0,05 мг/кг) примерно в 1,2 раза. Также установлено, что окунь аккумулирует тяжелые металлы интенсивнее плотвы. Экспериментальные данные совпадают с данными, полученными в мониторинговых водоемах. Установлено также, что концентрация Pb и Cd в тканях рыб зачастую превышает ПДК. Полученные результаты обязывают постоянно контролировать уровень тяжелых металлов в тканях рыб.

Developing Empirical Relationships to Predict Porosity and Microhardness of Atmospheric Plasma-Sprayed Alumina Coatings on AZ31B Magnesium Alloy

2015 ◽  
Vol 15 (2) ◽  
pp. 169-181 ◽  
Author(s):  
D. Thirumalaikumarasamy ◽  
K. Shanmugam ◽  
V. Balasubramanian
Keyword(s):  
Barrier Properties ◽  
Input Power ◽  
Atmospheric Plasma ◽  
Operational Parameters ◽  
Empirical Relationships ◽  
Alumina Coatings ◽  
Experimental Conditions ◽  
Wear And Corrosion Resistance ◽  
Two Parameters ◽  
Plasma Sprayed

AbstractPlasma-sprayed alumina coatings find wide-ranging applications by virtue of their inherent wear and corrosion resistance and attractive dielectric and diffusion barrier properties. In this work, empirical relationships were developed to predict the porosity and microhardness of alumina coatings by incorporating independently controllable atmospheric plasma-sprayed operational parameters (input power, stand-off distance and powder feed rate) using response surface methodology (RSM). A central composite rotatable design with three factors and five levels was chosen to minimize the number of experimental conditions. Within the scope of the design space, the input power and the stand-off distance appeared to be the most significant two parameters affecting the responses among the three investigated process parameters. A linear regression relationship was also established between porosity and microhardness of the alumina coatings.

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