Search

Tyramides are produced in microgram quantities by males of species in the large Myrmicine ant sub-family (> 7000 species). Tyramides are transferred to female sexuals during mating where a specific female sexual evolved enzyme hydrolyzes the tyramides to the biogenic amine, tyramine. Tyramine is a ligand for receptors that rapidly activate reproductive development in the newly mated queen—previously reproductively inhibited by the mother queen. Without this elaborate biogenic amine precursor and co-evolved female sexual derived tyramide hydrolase, the defenseless newly mated queen's worker production would be delayed by up to 6 days, which could be lethal to the new queen. This is one of possibly several ant species separation mechanisms evolved to maintain species integrity. Here we report two methyl-branched tyramides from harvester ant, Pogonomyrmex badius, males, including one highly branched tyramide not previously reported. [ABSTRACT FROM AUTHOR]

Recently, we proved that it was possible to significantly increase the importance of the species separation for binary mixtures, under microgravity, using forced convection obtained by a uniform translational displacement of the horizontal isothermal walls of the cell maintained at $T_{h}$ and $T_{c}$ respectively, with $\Delta T = T_{h} -T_{c}$.The present work is an extension of the study performed by Mojtabi (2020) with various mixtures, from binary to $n$-component mixtures. An application with a ternary mixture was presented. The mixture of tetralin, isobutyl benzene, $n$-dodecane with respectively 0.8–0.1–0.1 mass fractions was studied experimentally in weightlessness.

The Ranque-Hilsch vortex tube (RHVT) is a compact thermo-fluidic device primarily used to split a highly pressurized gaseous fluid into two different temperature streams. Vortex tubes are mainly known for their energy separation characteristic. But the interesting fact is that the vortex tube can also separate constituents of the fluid mixture into various phases. In some instances, the highly swirling fluid inside the RHVT gets split into distinct species at the outlets. This paper reviews previous vortex tube studies on energy, phases, and species separation to analyze the mechanism and their influencing parameters. The paper also includes a brief CFD study conducted on five working gases to show the nature of thermal separation. The effect of nozzle number and nozzle geometry, L/D ratio and divergent angle of the main tube, and conical valve geometry are discussed for each separation behavior. Operating parameters such as inlet pressure, temperature, and thermo-physical properties of working fluids are discussed for the efficient and optimized operation of RHVT. Reviewing the previous literature supported exploring more novel ideas in optimizing separation techniques, such as the appropriate selection of tube material, cooling of the hot tube, and insulation near the cold end. The analysis presented a broad application of RHVT utilizing its energy and mass separation behavior in several mechanical processes. The study also led to an understanding of the utility of RHVT in trans-critical refrigeration systems, water droplet separation, and liquid oxygen collection systems. [Display omitted] • The literature reviewed the studies on energy, phase, and species separation. • The impact of geometrical, and thermophysical parameters are discussed. • The Applications in trans-critical refrigeration, water droplet separation, LOX collection are shown, etc. • Other potential uses of separation characteristics have been explored. [ABSTRACT FROM AUTHOR]

Ring nematodes are obligate ectoparasites on crops and natural herbaceous and woody plants, and some species are of economic importance and cause damage to roots of several crops. Recent integrative taxonomical analyses recognized the existence of two cryptic species within the Criconema annuliferum morphotype in Spain. In this study, we corroborated that morphometric, morphological and a multi-locus analysis (including the ribosomal markers D2-D3 expansion segments of 28S rRNA, ITS rRNA, 18S RNA, and the mitochondrial DNA cytochrome oxidase I gene) identified a new lineage clearly separated from C. annuliferum, C. paraannuliferum and C. plesioannuliferum. The new lineage was described herein as Criconema pseudoannuliferum sp. nov., confirming that C. annuliferum species complex species complex comprises a hyper-cryptic species complex. This research analysed soil samples from the rhizosphere of maritime pine (Pinus pinaster Ait.) forests in Bermeja-Crestellina Mountain, located at the western part of Málaga province, southern Spain. The integrative taxonomical analyses revealed the occurrence of a new cryptic species identified using females, males and juveniles with detailed morphology, morphometry and molecular markers, described herein as Criconema pseudoannuliferum sp. nov. All molecular markers (D2-D3, ITS, 18S and COI) were obtained from the same individual that was also used for morphological and morphometric analyses. This research demonstrated the hidden diversity within the C. annuliferum species complex species complex can reach to four lineages under ribosomal and mitochondrial gene markers for one morphospecies group, which includes four species, viz. C. annuliferum, C. paraannuliferum, C. plesioannuliferum, and C. pseudoannuliferum sp. nov. Criconema pseudoannuliferum sp. nov. was detected in moderate soil density in two maritime pine forests (5 and 25 nematodes/500 cm3 of soil) suggesting that does not cause damage to maritime pine. [ABSTRACT FROM AUTHOR]

The columns commonly used for the species separation of a binary fluid are very thin vertical parallelepipedic columns, filled with a porous medium (i.e. TGC columns). This species separation is due to the mass flux induces by the thermal gradient applied on walls of the cavity, namely the Soret effect, in the gravity field. In this paper, a new configuration used to study the species separation in a binary fluid was presented. The evolution of species separation in a binary fluid saturating a porous media, in a cavity between two concentric spheres, was studied analytically and numerically. The thickness of the cavity is e = R o - R i , where R i and R o are the internal and external radii, respectively. First, an analytical solution was developed using the parallel flow approximation considering e ≪ R i . The analytical results obtained are in a good agreement with the numerical ones performed with a spectral method or Comsol Multiphysics software. Thus, the results in the spherical configuration were compared with those obtained in a porous TGC column of same thickness, e, height, H = π R i , and depth, L = 2 R o .The numerical and analytical studies showed that the differences in mass fractions, C max - C min , and the time needed to obtain the stationary separation starting from a homogeneous binary solution were almost equal in the two configurations. The amount of species separated is greater in the spherical configuration than in the vertical column used. [ABSTRACT FROM AUTHOR]

In this paper, an analytical and numerical analysis of the species separation in a binary mixture is performed. The main objective is to study the influence of the thickness and the nature of the bounding plates of the thermogravitational column (TGC) on species separation. The theory of Furry, Jones and Onsager is extended to the cases where bounding conducting walls enclose the TGC. The governing 2-dimensional equations are solved numerically using COMSOL Multiphysics software. A good agreement is found between the analytical and the numerical results. It is shown that the determination of the thermal diffusion coefficient, DT, from the measurement of the vertical mass fraction gradient of binary solutions, does not depend on the temperature difference imposed on the vertical column either on the outer walls of the cavity or on the inner walls in contact with the binary solutions. However, it is found that this result is no longer valid in the case of a binary gas. To our knowledge, in all earlier studies, dealing with the measurement of Soret coefficients in binary fluids, the nature and the thickness of the bounding walls were not considered.

Punctoribates is one of few genera in Poronota (Acari: Oribatida) containing species with porose areas and species with saccules, the two types of the octotaxic system. These porose organs are the main difference between two morphologically similar species, P. punctum with porose areas and P. zachvatkini with saccules. As the octotaxic system can vary within species, species separation solely based on this trait might be insufficient. To assess the species status of P. zachvatkini, we investigated additional differences from P. punctum by comparing habitat preferences of the two species regarding nature reserves and agricultural landscapes during a field study in the German Eifel region, and by examining Punctoribates material from four large German natural history museums. We also performed scanning electron microscopy (SEM) and a genetic analysis using the D3 marker of the nuclear 28S rDNA gene. In the field study, P. zachvatkini had higher densities in the nature reserves and P. punctum in the agricultural landscapes. Evaluation of the museum material revealed P. punctum occurred more regularly in disturbed sites such as urban, agricultural and post-mining areas compared to P. zachvatkini. Pairwise distances of the 28S D3 genetic marker as well as an additional base pair in P. zachvatkini further support the separation of the two species, and SEM investigations revealed new details regarding the punctulation of P. zachvatkini. The review of the museum material showed that P. zachvatkini already occurred in Germany in 1967 and has a wider distribution than previously known. [ABSTRACT FROM AUTHOR]

In this paper, an analytical and numerical analysis of the species separation in a binary mixture is performed. The main objective is to study the influence of the thickness and the nature of the bounding plates of the thermogravitational column (TGC) on species separation. The theory of Furry, Jones and Onsager is extended to the cases where bounding conducting walls enclose the TGC. The governing 2-dimensional equations are solved numerically using COMSOL Multiphysics software. A good agreement is found between the analytical and the numerical results. It is shown that the determination of the thermal diffusion coefficient, DT, from the measurement of the vertical mass fraction gradient of binary solutions, does not depend on the temperature difference imposed on the vertical column either on the outer walls of the cavity or on the inner walls in contact with the binary solutions. However, it is found that this result is no longer valid in the case of a binary gas. To our knowledge, in all earlier studies, dealing with the measurement of Soret coefficients in binary fluids, the nature and the thickness of the bounding walls were not considered. [ABSTRACT FROM AUTHOR]

Ring nematodes are obligate ectoparasites on crops and natural herbaceous and woody plants, and some species are of economic importance and cause damage to roots of several crops. Recent integrative taxonomical analyses recognized the existence of two cryptic species within the Criconema annuliferum morphotype in Spain. In this study, we corroborated that morphometric, morphological and a multi-locus analysis (including the ribosomal markers D2-D3 expansion segments of 28S rRNA, ITS rRNA, 18S RNA, and the mitochondrial DNA cytochrome oxidase I gene) identified a new lineage clearly separated from C. annuliferum, C. paraannuliferum and C. plesioannuliferum. The new lineage was described herein as Criconema pseudoannuliferum sp. nov., confirming that C. annuliferum species complex species complex comprises a hyper-cryptic species complex. This research analysed soil samples from the rhizosphere of maritime pine (Pinus pinaster Ait.) forests in Bermeja-Crestellina Mountain, located at the western part of Málaga province, southern Spain. The integrative taxonomical analyses revealed the occurrence of a new cryptic species identified using females, males and juveniles with detailed morphology, morphometry and molecular markers, described herein as Criconema pseudoannuliferum sp. nov. All molecular markers (D2-D3, ITS, 18S and COI) were obtained from the same individual that was also used for morphological and morphometric analyses. This research demonstrated the hidden diversity within the C. annuliferum species complex species complex can reach to four lineages under ribosomal and mitochondrial gene markers for one morphospecies group, which includes four species, viz. C. annuliferum, C. paraannuliferum, C. plesioannuliferum, and C. pseudoannuliferum sp. nov. Criconema pseudoannuliferum sp. nov. was detected in moderate soil density in two maritime pine forests (5 and 25 nematodes/500 cm3 of soil) suggesting that does not cause damage to maritime pine.

Tyramides are produced in microgram quantities by males of species in the large Myrmicine ant sub-family (> 7000 species). Tyramides are transferred to female sexuals during mating where a specific female sexual evolved enzyme hydrolyzes the tyramides to the biogenic amine, tyramine. Tyramine is a ligand for receptors that rapidly activate reproductive development in the newly mated queen-previously reproductively inhibited by the mother queen. Without this elaborate biogenic amine precursor and co-evolved female sexual derived tyramide hydrolase, the defenseless newly mated queen's worker production would be delayed by up to 6 days, which could be lethal to the new queen. This is one of possibly several ant species separation mechanisms evolved to maintain species integrity. Here we report two methyl-branched tyramides from harvester ant, Pogonomyrmex badius, males, including one highly branched tyramide not previously reported., (© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

• A new process of species separation in a binary mixture, using mixed convection, is presented. • In a first part, an analytical solution was developed using the parallel flow approximation. 2D and 3D direct numerical simulations were performed in order to corroborate the analytical results. • The influence of the two horizontal walls velocities on the diffusive relaxation time was determined numerically. • The authors demonstrated that the optimum species separation was obtained when the two horizontal walls are moving at equal velocity but in opposite direction. The coupling between shear-driven convection and thermo-diffusion is a complex phenomenon due to the interactions between the different forces inside the fluid mixture. This paper studies the species separation that may appear in a parallelepipedic cell filled by a binary mixture. Dirichlet boundary conditions are imposed with differentially heated horizontal walls. Each wall can be animated with a uniform velocity. More precisely, two velocities U P e x → , a n d f U P e x → are applied at the upper and the lower horizontal walls respectively. An analytical solution, based on the parallel flow approximation in the core region of the cavity of large aspect ratio, is obtained as a function of the dimensionless parameters of the problem. The species separation is optimized according to the multiple control parameters of the problem. The velocity field obtained is the superposition of the flow generated by the velocity of the walls under weightless conditions and thermoconvective flow under gravity only. The combination of these two flows leads to a mixed convection flow with a single convective cell for f ∈ - 1 , 0 and two superposed cells for f ∈ 0 , 1 . Only unicellular flow leads to a notable species separation. This study shows that the effective species separation admits a partial optimum as a function of f and U p. As in the case of thermogravitational columns, there is no optimum species separation with respect to parameters Δ T and H but, for a fixed temperature difference Δ T , there is a thickness H that optimizes the separation and vice versa. 2 D and 3 D direct numerical simulations are performed using a finite element method in order to corroborate the analytical results. The influence of mass Péclet number on the diffusive relaxation time is determined numerically. Taking into account the confinement of the medium in the third dimension, perpendicular to a vertical plane, we show that the aspect ratio in the y-direction has an influence on the species separation. [ABSTRACT FROM AUTHOR]

Norwegian coastal cod (Gadus morhua) protection restricts the use of active fishing gears. Demersal seines, acknowledged as being efficient for targeting flatfish, are therefore largely excluded from the fjords. To exploit plaice (Pleuronectes platessa), a species-selective gear that avoids catching cod is needed. We therefore designed a low-rise demersal seine with a 0.6 m vertical opening and tested it on fishing grounds in Lofoten (Northern Norway), comparing it with a conventional seine that had a vertical opening of ∼3.5 m, and fished both during the day and at night. Six to nine hauls were taken with each of the four gear/time-of-day categories (32 hauls in total). The low-rise seine caught no fewer plaice during day-time fishing, but less at night. Cod and haddock (Melanogrammus aeglefinus) catches were reduced by 94% and 98%, respectively, while catches of sole (Solea solea) increased with the low-rise seine. No catch differences were found for halibut (Hippoglossus hippoglossus), common dab (Limanda limanda), or monkfish (Lophius piscatorius). The low-rise seine therefore enables targeting flatfish while avoiding gadoid catches, although loss of plaice during night-time fishing is to be expected. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Spatial separation of pyrrole and pyrrole(H 2 O) from other species in a molecular beam. • Our experimental findings are supported by simulations. • Pure sample of pyrrole(H 2 O) clusters. Abstract We demonstrate the spatial separation of pyrrole and pyrrole(H 2 O) clusters from the other atomic and molecular species in a supersonically-expanded beam of pyrrole and traces of water seeded in high-pressure helium gas. The experimental results are quantitatively supported by simulations. The obtained pyrrole(H 2 O) cluster beam has a purity of ∼ 100 %. The extracted rotational temperature of pyrrole and pyrrole(H 2 O) from the original supersonic expansion is T rot = 0.8 ± 0.2 K, whereas the temperature of the deflected, pure-pyrrole(H 2 O) part of the molecular beam corresponds to T rot ≈ 0.4 K. [ABSTRACT FROM AUTHOR]

The vortex tube uses energy separation technology to separate inlet gases into hotter and colder mixtures than the inlet state. In this research, a feasibility study is carried out on a vortex tube used to separate CO 2 gas from air-CO 2 gas mixture at atmospheric temperature. Prior to the feasibility experiment, transient response of vortex tube is investigated to determine the time needed to achieve steady state temperature of energy separation. The experimental parameters of gas separation are the pressures and concentrations of CO 2 that is mixed with air. Results show that CO 2 gas separation is proportional to operating pressure. The results also show that the cold mass fraction is a core parameter for gas separation. The percentage mass fraction of separated CO 2 gas at cold exit is 7.4% at 3  bar g and cold mass fraction of 0.6. [ABSTRACT FROM AUTHOR]

In this paper, an analytical and numerical study of species separation in binary mixtures taking account of the presence of bounding plates for the cell is presented. A rectangular horizontal porous cavity saturated by a binary mixture and heated from below is considered. This cavity is bounded by thin plates of uniform thickness, the outer surfaces of which are subjected to a constant heat flux. The transition from the equilibrium solution to the convective one, either stationary or oscillatory, was previously studied by Ouattara et al. (2012). Thus in the first part of this paper, the critical parameters associated with the onset of long wavelength disturbances, obtained analytically, are recalled. Then the hypothesis of parallel flow is used to determine an analytical solution which describes the unicellular flow which may appear in the case of a large aspect ratio cell for a given range of separation ratio, ψ , Rayleigh number, Ra , Lewis number, Le, the ratio of the plate to the porous layer thickness, δ, and their thermal conductivity ratio, d . The analytical results are corroborated by direct numerical simulations. We verify that if d goes to infinity, the walls become infinitely conductive and we find the results obtained by Charrier-Mojtabi et al. (2007). When d tends to 0, the walls become infinitely thin the results obtained by Yacine et al. (2016) are recovered. A linear stability analysis of the unicellular flow is also presented. The eigenvalue problem resulting from the temporal stability analysis is solved by a Tau spectral method. The optimal Rayleigh number leading to an optimal value of the separation horizontal gradient is determined for different values of physical parameters. We show that the species separation depends sensitively on the ratio of the plate to the porous layer thickness, and the ratio of their thermal conductivities. Furthermore, we have shown that in the stationary state and for a given value of the thermal conductivity ratio ( d  = 29), the maximum separation is almost equal for walls of the same thickness than the one of porous cavity or for the case of porous cell delimited by the infinitely thin walls. [ABSTRACT FROM AUTHOR]

We present an analytical and numerical stability analysis of Soret-driven convection in a porous cavity saturated by a binary fluid mixture and subjected to vertical high-frequency and small-amplitude vibrations. Two configurations have been considered and compared: an infinite horizontal layer and a bounded domain with a large aspect ratio. In both cases, the initial temperature gradient is produced by a constant uniform heat flux applied on the horizontal boundaries. A formulation using time-averaged equations is used. The linear stability of the equilibrium solution is carried out for various Soret separation ratios φ, vibrational Rayleigh numbers Rv, Lewis numbers Le and normalized porosity. For an infinite horizontal layer, the critical Rayleigh number Rac is determined analytically. For a steady bifurcation to a one-cell solution (the critical wavenumber is zero), we obtain Rac=12/(φ(Le+1)+1) for all Rv. When the bifurcation is a Hopf bifurcation or when the critical wavenumber is not zero, we use a Galerkin method to compute the critical values. Our study is completed by a nonlinear analysis of the bifurcation to one-cell solutions in an infinite horizontal layer that is compared to numerical simulations in bounded horizontal domains with large aspect ratio. [ABSTRACT FROM AUTHOR]

In management of fisheries, knowledge about the species is crucial due to differences in life history traits. The first step is therefore species identification. For many species this task is straightforward, however for some species e.g. the two species of Atlantic redfish Sebastes mentella and Sebastes norvegicus , it can be difficult for an untrained eye. With the goal to separate the two species, we analysed otolith shape variation of S. mentella and S. norvegicus caught on the continental slope of East Greenland using the R package “Shape R”. Results were evaluated against genetic analysis of the same fish, and compared to results of both a visual identification of the two species and a separation based on a linear discriminant analysis on standardised values of fish length, fish weight and otolith weight. It was concluded that the objective otolith shape analysis using the Shape R package analysis achieve a reasonable classification success, however with a clear bias towards S. mentella . Classification using the otolith weight achieved a slightly higher success than the shape analysis making it a promising method. Furthermore, the method is at the same time both objective, less time consuming than the otolith shape analysis and less expensive than genetic analysis. However, the visual classification method of the whole fish had the highest success rate of the three tested methods, which despite the need for trained technicians makes it the most successful method. [ABSTRACT FROM AUTHOR]

In the present study we applied a discriminant function analysis to distinguish two fairy shrimp species, Branchipus schaefferi and Tanymastix stagnalis (Anostraca), co-occurring in Lago dell'Orso in central Italy. Our aim was to obtain information on the pattern of coexistence of these two species to investigate their syntopy since early larval stages. To identify the larvae of the two species we used six discriminant functions, one for each larval stage considered (nauplius, four metanauplius stages and juvenis), and based on morphometric analyses and measurements of different traits (thoracic appendages, body length, length of first antenna, length of head, thorax length and length of furca). The pool was visited at weekly intervals during two time periods for a total of 4 years (1995-1996 and 2000-2001) and physical and chemical variables (water level, water and air temperature, pH and conductivity) were recorded. A total of 1067 specimens were collected, measured and morphometrically identified. B. schaefferi was more abundant and persistent than T. stagnalis. At any stage, T. stagnalis was bigger than B. schaefferi and this difference may justify niche differentiation between coexisting species. Difference in size might be linked to difference in life-span as B. schaefferi reproduced earlier and at a smaller size than T. stagnalis. When the hydroperiod is short, B. schaefferi might be the only species to produce resting eggs in time for reproduction. On the other hand, T. stagnalis may have an advantage in the longest hydroperiods. In an ephemeral seasonal pond such as Lago dell'Orso, coexistence can be fostered and competitive exclusion can be prevented as a result of seasonal environmental changes. [ABSTRACT FROM AUTHOR]

Copyright of Acta Scientiarum: Biological Sciences is the property of Universidade Estadual de Maringa and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Species separation can be produced by imposing a pressure gradient in gaseous mixtures, which induces different molecular velocities depending on the molar weight. Pressure gradients can be achieved by centrifugal forces brought about by the passage of the gas through a curved nozzle at supersonic velocity. The efficiency of this process depends on the geometry of the nozzle as well as the flow operating conditions. The numerical solver Fluent was used in order to produce a model of the aerodynamics and the oxygen diffusion of a steady-state flow of air in a curved nozzle. The development of the pressure and O 2 concentration profiles along the nozzle were analyzed for different pressure boundary conditions at the inlet and the exit, testing several nozzle sizes. Optimum values of the cut and the inlet pressure were found which maximize the separation efficiency. The effect of the exit pressure was associated with the axial pressure distribution along the inner wall of the nozzle. The results were compared with measurements showing good agreement. [ABSTRACT FROM AUTHOR]

An analytical and numerical study of Soret-driven convection in a horizontal porous layer saturated by a binary fluid and subjected to uniform cross heat fluxes is presented. The flow is driven by the combined buoyancy effect due to temperature and induced mass fraction variations through a binary water ethanol mixture. In the first part of the study, a closed-form analytical solution in the limit of a large aspect ratio of the cell ( A >> 1) is developed. We are mainly concerned with the determination of the mass fraction gradient of the component of interest along the horizontal direction, which determines the species separation. In the second part, numerous numerical simulations are carried out in order to validate the analytical results and extend heat and mass transfer to an area not covered by the analytical study. Good agreement is found between analytical and numerical results concerning the species separation obtained for a unicellular flow. In this configuration, the Soret separation process is improved by two control parameters: the heat flux density imposed on the horizontal walls of the cell and the ratio, a , of heat flux density imposed on vertical walls to that on horizontal walls. The influence of the heat flux density ratio, a , on the transient regime (relaxation time) is also investigated numerically. We observe that an increase in the parameter a leads to a decrease in the relaxation time. Thus, for a cell heated from below without lateral heating, the onset of convection from the mechanical equilibrium state is analyzed. The linear stability analysis shows that the equilibrium solution loses its stability via a stationary bifurcation or a Hopf bifurcation depending on the separation ratio and the normalized porosity of the medium. The linear stability results are widely corroborated by direct 2D numerical simulations. The thresholds of various multicellular solutions are determined in terms of the governing parameters of the problem using nonlinear direct numerical simulations. [ABSTRACT FROM AUTHOR]

Most demersal trawl fisheries are conducted in a multispecies setting, and the catch consists of several different species. An inherent challenge in such fisheries is to provide both biologically and economically sustainable exploitation of individually fluctuating stocks and vessel- or fleet-specific quotas. The topless trawl design was developed to improve species-specific selectivity in such fisheries. In a topless trawl, the foot rope is located more forward than the headline to allow fish to escape upwards, whereas the headline is located in front in traditional trawl designs. In this study we conducted twin trawls with a topless trawl towed parallel to a similar standard trawl; we tested a topless trawl design on a small trawl with a low headline height and on a larger trawl with a high headline height. We conducted the tows in the Nephrops ( Nephrops norvegicus ) directed mixed fisheries. For both the small and large trawls, we found a significant topless effect for haddock ( Melanogramus aeglefinus ) and no effect for Nephrops . For Atlantic cod ( Gadus morhua ) we found a significant topless effect for the low headline trawl but no effect for the high headline trawl. In both the eastern and western Atlantic, topless trawls have been introduced as legal cod-selective trawl designs. However, this study demonstrates that identical gear modifications made to similar trawls of different sizes and used in the same fishery can lead to different results. [ABSTRACT FROM AUTHOR]

Eastern Palearctic conifers are subject to frequent bark beetle outbreaks. However, neither the species responsible nor the semiochemicals guiding these attacks are well understood. Two high-mountain Ips species on Qinghai spruce, Picea crassifolia, I. shangrila and I. nitidus, are typical in this regard. Six synthetic candidate pheromone components that we earlier identified from hindguts of unmated males of these two Ips species were tested for field activity in Qinghai province, P. R. China. For I. nitidus, racemic ipsdienol ((±)-Id) could replace the naturally-produced blend of enantiomers containing 74 % (-)-( S)-Id (74:26 S: R), in attractive ternary or binary blends. In contrast, sympatric I. shangrila were attracted mainly to blends including Id of opposite chirality, 97 %-(+)-( R)-Id. Of the verbenols, (-)- trans-verbenol was inactive for I. nitidus or inhibitory for I. shangrila, but (-)- cis-verbenol (cV) was a key component of the pheromone in both species. Two fully factorial experiments demonstrated that (±)-Id, cV, and 2-methyl-3-buten-2-ol (MB) are components of the aggregation pheromone of I. nitidus, whereas only (+)-Id and cV are essential components of the aggregation pheromone of I. shangrila. While MB is not necessary for attraction of I. shangrila, it is an active antagonist and likely functions in species isolation. A review of the pheromone production and responses in Palearctic Ips and Pseudoips showed that cV is more common than methylbutenols, and both elicit qualitatively variable responses. Ipsdienol is the most common component with variable chirality, and is a necessary, but often not sufficient, factor for determining pheromone specificity. [ABSTRACT FROM AUTHOR]

Shape descriptors of sagittal otoliths were applied to the identification of four sympatric species of the genus Sebastes ( Sebastes schlegeli, S. hubbsi, S. nudus and S. thompsoni) inhabiting the coastal reefs of the Bohai Sea and the Yellow Sea, northwest Pacific. Canonical discriminate analysis of standard length-corrected otolith shape variables (a combination of shape indices and elliptic Fourier coefficients) was demonstrated to be a useful tool for species identification with a high overall classification success of 96.6 %. An otolith morphological tree based on hierarchical average linkage cluster analysis indicated the closest proximity was between S. hubbsi and S. nudus. The otolith morphological affinities coincide well with the phylogenetic relationships reported among these species, which indicates the potential to use otolith morphology to establish phylogenetic relationships in this genus. In addition, ecomorphological comparisons suggest that the otolith shapes might be influenced by several ecological and environmental components such as depth, body color and substrate type. Among the environmental factors, depth could be the most comprehensive factor associated with the inter-specific variations of otolith morphology. [ABSTRACT FROM AUTHOR]

Achieving effective size selectivity for different species within a fishing gear is a major challenge in mixed fisheries. Fish behaviour may be exploited to separate species into separate codends where different selective properties can then be applied. Within the Basque bottom trawl fishery such a set-up has never been tested despite species with different behaviours being present. In this study, we investigate if species separation can be achieved through the use of a horizontal grid, where species typically found close to the seabed are intended to pass through the horizontal grid into the lower codend, while maintaining other species in an upper codend. Furthermore, the effect of artificial light on grid passage probability was estimated. Results were obtained for five fish species of commercial interest in the Basque bottom trawl fishery. Less than 25% of the individuals of all species analysed passed through the grid and were retained in the lower codend, and no significant differences were found when the grid was illuminated. The specific conditions under which the Basque bottom trawl fishery is conducted, i.e., high turbidity levels, high towing speed, may have influenced the performance of the gear in this fishery. Consequently, the design was found to have limited potential to improve species and size selection in the Basque bottom trawl fishery. [ABSTRACT FROM AUTHOR]

• Mass transport by oscillatory electroosmotic flow in a microannulus is analyzed. • Oscillatory electroosmotic flow of a Maxwell fluid is considered. • Separation of electro neutral species is studied. • Conditions for better mixing and separation of species are found. In this work we develop a theoretical analysis for the mass transfer of an electroneutral solute in a concentric-annulus microchannel driven by an oscillatory electroosmotic flow (OEOF) of a fluid whose behavior follows the Maxwell model. The annular microchannel connects two reservoirs that have different concentrations of the solute. For the mathematical modeling of the OEOF, we assume the Debye-Hückel approximation and that the wall zeta potentials of the micro-annulus can be symmetric or asymmetric. The governing equations are nondimensionalized, from which the following dimensionless parameters appear: an angular Reynolds number, the ratio of the wall zeta potentials of the annular microchannel, the electrokinetic parameter, the dimensionless gap between the two cylinders, the Schmidt number and the elasticity number. The results indicate that the velocity and concentration distributions across the annular microchannel become non-uniform as the angular Reynolds number increases, and depend notably on the elasticity number. It is also revealed that with a suitable combination of values of the elasticity number and gap between the two cylinders, together with the angular Reynolds number, the total mass transport rate can be increased and the species separation can be controlled. [ABSTRACT FROM AUTHOR]

In the presence of a gravity field or under microgravity, pure thermo-diffusion leads to very weak species separation in binary mixtures. To increase the species separation in the presence of gravity, many authors use thermo-gravitational diffusion in vertical columns (TGC). For a given binary mixture, the species separation between the top and the bottom of these columns depends on the temperature difference, ΔT , imposed between the two vertical walls facing each other, and the thickness, H, between these two walls (annular or parallelepipedic column). These studies show that, for a fixed temperature difference, the species separation is optimal for a thickness, H o p t , much smaller than one millimetre. The species separation decreases sharply when the thickness H decreases with respect to this optimum value. It decreases progressively as H increases with respect to H o p t . In addition, for mixtures with a negative thermo-diffusion coefficient, the heaviest component migrates towards the upper part of the column and the lightest one towards the lower part. The loss of stability of the configuration thus obtained leads to a brutal homogeneity of the binary solution. The objective of this study in microgravity was to increase the optimum of species separation. For this purpose, the binary fluid motion was provided by uniform velocities imposed on the two walls of the cavity facing each other. This forced flow led to species separation between the two motionless walls of the cavity. In this case, the fluid motion generated in the cavity was not dependent on the imposed temperature difference, ΔT contrarily to the case of thermogravitational column. Under these conditions and for a given column of thickness H, there are three independent control parameters: ΔT and the two velocities of the walls facing each other. Using the parallel flow approximation for a cell of large aspect ratio, the velocity, temperature and mass fraction fields within the cavity were determined analytically. Thus the parameters leading to optimal species separation were calculated. The analytical results were corroborated by direct numerical simulations. The present paper thus proposes a new process for the determination of the Soret coefficient, the thermodiffusion coefficient and mass-diffusion coefficient. [ABSTRACT FROM AUTHOR]

Bottom-trawl fishing for crustaceans off the Portuguese south and southwest coasts is a very important segment of the Portuguese fishing fleet, where annual rates of discarding have ranged from approximately 38% to as much as 70% of the total catch. Past experiments to address this problem encompassed the testing of different codend mesh sizes and configurations, square mesh windows and rigid grids to enhance species and size-selectivity. While the use of a Nordmøre grid has proved quite efficient in separating out blue whiting (Micromesistius poutassou), it also led to some losses of the two main crustacean target species, Norway lobster (Nephrops norvegicus) and rose shrimp (Parapenaeus longirostris). The present study addresses that limitation by using a modified grid with 20 mm bar spacing and two open sections, designed with the purpose of separating fish and crustacean species into upper and lower codends. Good separation was achieved, with about 80% of the blue whiting (in number) directed towards the upper trawl section and caught in the upper codend, while a similar percentage of Norway lobster was caught in the lower codend. The grid bars had 50% retention for Norway lobster at 34.1 mm carapace length. The results herein will enable this gear configuration to be fine-tuned with regard to codend mesh sizes and bar spacing, so as to optimize both retention of Norway lobster and exclusion of blue whiting. For example, compared to using the minimum 70 mm diamond mesh size, using an 80 mm diamond mesh upper codend would reduce Norway lobster catch weight by just 1.6% but reduce the number of blue whiting caught by 42%. [ABSTRACT FROM AUTHOR]