scholarly journals Sperm competition and fertilization mode in fishes

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200074
Author(s):  
John L. Fitzpatrick
Keyword(s):  
Sperm Competition ◽  
Biological Diversity ◽  
Swimming Performance ◽  
Multiple Paternity ◽  
Mode Shapes ◽  
Internal Fertilization ◽  
Animal Evolution ◽  
Bony Fishes ◽  
Wide Range ◽  
Theoretical Predictions

Sperm competition is a powerful selective force that has shaped sexual traits throughout animal evolution. Yet, how fertilization mode (i.e. external versus internal fertilization) influences the scope and potential for sperm competition to act on ejaculates remains unclear. Here, I examine how fertilization mode shapes ejaculatory responses to sperm competition in fishes, a diverse group that constitute the majority of vertebrate biological diversity. Fishes are an ideal group for this examination because they exhibit a wide range of reproductive behaviours and an unparalleled number of transitions in fertilization mode compared to any other vertebrate group. Drawing on data from cartilaginous and bony fishes, I first show that rates of multiple paternity are higher in internally than externally fertilizing fishes, contrary to the prevailing expectation. I then summarize how sperm competition acts on sperm number and quality in internally and externally fertilizing fishes, highlighting where theoretical predictions differ between these groups. Differences in how ejaculates respond to sperm competition between fertilization modes are most apparent when considering sperm size and swimming performance. Clarifying how fertilization mode influences evolutionary responses in ejaculates will inform our understanding of ejaculate evolution across the animal tree of life. This article is part of the theme issue ‘Fifty years of sperm competition’.

scholarly journals Seminal fluid and accessory male investment in sperm competition

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200068
Author(s):  
Steven A. Ramm
Keyword(s):  
Sperm Competition ◽  
Seminal Fluid ◽  
Complex Mixture ◽  
Internal Fertilization ◽  
Animal Evolution ◽  
Male Investment ◽  
Trade Offs ◽  
Fluid Production ◽  
Alternative Routes ◽  
Paternity Success

Sperm production and allocation strategies have been a central concern of sperm competition research for the past 50 years. But during the ‘sexual cascade’ there may be strong selection for alternative routes to maximizing male fitness. Especially with the evolution of internal fertilization, a common and by now well-studied example is the accessory ejaculate investment represented by seminal fluid, the complex mixture of proteins, peptides and other components transferred to females together with sperm. How seminal fluid investment should covary with sperm investment probably depends on the mechanism of seminal fluid action. If seminal fluid components boost male paternity success by directly enhancing sperm function or use, we might often expect a positive correlation between the two forms of male investment, whereas trade-offs seem more likely if seminal fluid acts independently of sperm. This is largely borne out by a broad taxonomic survey to establish the prevailing patterns of seminal fluid production and allocation during animal evolution, in light of which I discuss the gaps that remain in our understanding of this key ejaculate component and its relationship to sperm investment, before outlining promising approaches for examining seminal fluid-mediated sperm competitiveness in the post-genomic era. This article is part of the theme issue ‘Fifty years of sperm competition’.

QCD at Fixed Order: Processes

2018 ◽  
Author(s):  
John Campbell ◽  
Joey Huston ◽  
Frank Krauss
Keyword(s):  
Hadron Collider ◽  
Detailed Comparison ◽  
Theoretical Description ◽  
Higgs Bosons ◽  
Final States ◽  
Collider Physics ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Fixed Order ◽  
The Subject

At the core of any theoretical description of hadron collider physics is a fixed-order perturbative treatment of a hard scattering process. This chapter is devoted to a survey of fixed-order predictions for a wide range of Standard Model processes. These range from high cross-section processes such as jet production to much more elusive reactions, such as the production of Higgs bosons. Process by process, these sections illustrate how the techniques developed in Chapter 3 are applied to more complex final states and provide a summary of the fixed-order state-of-the-art. In each case, key theoretical predictions and ideas are identified that will be the subject of a detailed comparison with data in Chapters 8 and 9.

SIMULATION OF AN AXISYMMETRIC RISING BUBBLE BY A MULTIPLE RELAXATION TIME LATTICE BOLTZMANN METHOD

2009 ◽  
Vol 23 (24) ◽  
pp. 4907-4932 ◽  
Author(s):  
ABBAS FAKHARI ◽  
MOHAMMAD HASSAN RAHIMIAN
Keyword(s):  
Free Surface ◽  
Lattice Boltzmann Method ◽  
Lattice Boltzmann ◽  
Rise Velocity ◽  
Rising Bubble ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Multiple Relaxation Time ◽  
Bubble Rising ◽  
Boltzmann Method

In this paper, the lattice Boltzmann method is employed to simulate buoyancy-driven motion of a single bubble. First, an axisymmetric bubble motion under buoyancy force in an enclosed duct is investigated for some range of Eötvös number and a wide range of Archimedes and Morton numbers. Numerical results are compared with experimental data and theoretical predictions, and satisfactory agreement is shown. It is seen that increase of Eötvös or Archimedes number increases the rate of deformation of the bubble. At a high enough Archimedes value and low Morton numbers breakup of the bubble is observed. Then, a bubble rising and finally bursting at a free surface is simulated. It is seen that at higher Archimedes numbers the rise velocity of the bubble is greater and the center of the free interface rises further. On the other hand, at high Eötvös values the bubble deforms more and becomes more stretched in the radial direction, which in turn results in lower rise velocity and, hence, lower elevations for the center of the free surface.

Interactive effects of salinity on metabolic rate, activity, growth and osmoregulation in the euryhaline milkfish (Chanos chanos)

1998 ◽  
Vol 201 (24) ◽  
pp. 3355-3366
Author(s):  
C Swanson
Keyword(s):  
Metabolic Rate ◽  
High Salinity ◽  
Swimming Performance ◽  
Interactive Effects ◽  
Routine Activity ◽  
Swimming Velocity ◽  
Activity Levels ◽  
Salinity Adaptation ◽  
Chanos Chanos ◽  
Wide Range

The euryhaline milkfish (Chanos chanos) is an excellent subject for studies of the physiological and behavioral processes involved in salinity adaptation. In this study, energy partitioning for metabolism, activity and growth, maximal activity performance and blood osmotic concentrations were assessed at two activity levels in juvenile milkfish fed equal rations and maintained at a relatively constant temperature (262 C) and at salinities(15, 35 and 55 ?) that represented a wide range of osmoregulatory challenges. Changes in the measured parameters were not consistently related to the magnitude of the trans-integumentary osmotic gradients. Routine oxygen consumption rates were high in 35 ? salinity (mean 1 s.e.m. 1678 mg O2 kg-1 h-1) and comparably low in 15 and 55 ? salinity (1336 and 1273 mg O2 kg-1 h-1, respectively). Routine activity levels (relative swimming velocity) were highest in 35 ? salinity (0. 960.04 L s-1), where L is standard length, intermediate in 15 ? salinity (0.770.03 L s-1) and lowest in 55 ? salinity (0.670.03 L s-1). Growth was significantly higher in 55 ? salinity (3.40.2 % increase in wet body mass per day) than in 35 ?salinity (2.40.2 % increase per day) and intermediate in 15 ? salinity(2.90.5 % increase per day). Maximum swimming velocities decreased with increases in salinity, from 9.90.7 L s-1 in 15 ? salinity to 6.60. 5 L s-1 in 55 ? salinity. Sustained swimming activity above routine levels for 2 h resulted in an increase in blood osmotic concentrations in milkfish in 55 ?salinity, but osmoregulation was re-established during the second 2 h of activity. Thus, patterns of variation in metabolic rate and growth were largely parallel to variations in routine activity although, comparing 15 and 55 ? salinity, elevated maintenance costs for osmoregulation at the high salinity were detectable. Reduced osmoregulatory abilities and reductions in maximal swimming performance suggest that high salinity may constrain activity. The results demonstrate that investigations of salinity adaptation in euryhaline fishes should take into account the interactive effects of salinity on physiology and behavior.

scholarly journals Triadic resonances in precessing rapidly rotating cylinder flows

2015 ◽  
Vol 778 ◽  
Author(s):  
T. Albrecht ◽  
H. M. Blackburn ◽  
J. M. Lopez ◽  
R. Manasseh ◽  
P. Meunier
Keyword(s):  
Rotating Cylinder ◽  
Direct Numerical Simulations ◽  
Mode Shapes ◽  
Resonance Model ◽  
Rapid Rotation ◽  
Nutation Angle ◽  
Resonant Instability ◽  
Theoretical Predictions ◽  
Long Time ◽  
Good Agreement

Direct numerical simulations of flows in cylinders subjected to both rapid rotation and axial precession are presented and analysed in the context of a stability theory based on the triadic resonance of Kelvin modes. For a case that was chosen to provide a finely tuned resonant instability with a small nutation angle, the simulations are in good agreement with the theory and previous experiments in terms of mode shapes and dynamics, including long-time-scale regularization of the flow and recurrent collapses. Cases not tuned to the most unstable triad, but with the nutation angle still small, are also in quite good agreement with theoretical predictions, showing that the presence of viscosity makes the physics of the triadic-resonance model robust to detuning. Finally, for a case with $45^{\circ }$ nutation angle for which it has been suggested that resonance does not occur, the simulations show that a slowly growing triadic resonance predicted by theory is in fact observed if sufficient evolution time is allowed.

scholarly journals A protocol for an intercomparison of biodiversity and ecosystem services models using harmonized land-use and climate scenarios

2018 ◽  
Vol 11 (11) ◽  
pp. 4537-4562 ◽  
Author(s):  
HyeJin Kim ◽  
Isabel M. D. Rosa ◽  
Rob Alkemade ◽  
Paul Leadley ◽  
George Hurtt ◽  
...  
Keyword(s):  
Climate Change ◽  
Land Use ◽  
Ecosystem Services ◽  
Biological Diversity ◽  
Multiple Scales ◽  
Convention On Biological Diversity ◽  
Second Phase ◽  
Intergovernmental Panel ◽  
Wide Range ◽  
Global Impacts

Abstract. To support the assessments of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES), the IPBES Expert Group on Scenarios and Models is carrying out an intercomparison of biodiversity and ecosystem services models using harmonized scenarios (BES-SIM). The goals of BES-SIM are (1) to project the global impacts of land-use and climate change on biodiversity and ecosystem services (i.e., nature's contributions to people) over the coming decades, compared to the 20th century, using a set of common metrics at multiple scales, and (2) to identify model uncertainties and research gaps through the comparisons of projected biodiversity and ecosystem services across models. BES-SIM uses three scenarios combining specific Shared Socio-economic Pathways (SSPs) and Representative Concentration Pathways (RCPs) – SSP1xRCP2.6, SSP3xRCP6.0, SSP5xRCP8.6 – to explore a wide range of land-use change and climate change futures. This paper describes the rationale for scenario selection, the process of harmonizing input data for land use, based on the second phase of the Land Use Harmonization Project (LUH2), and climate, the biodiversity and ecosystem services models used, the core simulations carried out, the harmonization of the model output metrics, and the treatment of uncertainty. The results of this collaborative modeling project will support the ongoing global assessment of IPBES, strengthen ties between IPBES and the Intergovernmental Panel on Climate Change (IPCC) scenarios and modeling processes, advise the Convention on Biological Diversity (CBD) on its development of a post-2020 strategic plans and conservation goals, and inform the development of a new generation of nature-centred scenarios.

scholarly journals An investigation into the free vibrations of carbon nanotubes using analytical and finite element methods

2021 ◽  
Author(s):  
Ishan Ali Khan
Keyword(s):  
Carbon Nanotubes ◽  
Finite Element ◽  
Eigenvalue Problem ◽  
Natural Frequencies ◽  
Nonlinear Eigenvalue Problem ◽  
Dynamic Stiffness ◽  
Free Vibrations ◽  
Mode Shapes ◽  
Wide Range ◽  
Walled Cnts

Since their discovery, immense attention has been given to carbon nanotubes (CNTs), due to their exceptional thermal, electronic and mechanical properties and, therefore, the wide range of applications in which they are, or can be potentially, employed. Hence, it is important that all the properties of carbon nanotubes are studied extensively. This thesis studies the vibrational frequencies of double-walled and triple-walled CNTs, with and without an elastic medium surrounding them, by using Finite Element Method (FEM) and Dynamic Stiffness Matrix (DSM) formulations, considering them as Euler-Bernoulli beams coupled with van der Waals interaction forces. For FEM modelling, the linear eigenvalue problem is obtained using Galerkin weighted residual approach. The natural frequencies and mode shapes are derived from eigenvalues and eigenvectors, respectively. For DSM formulation of double-walled CNTs, a nonlinear eigenvalue problem is obtained by enforcing displacement and load end conditions to the exact solution of single equation achieved by combining the coupled governing equations. The natural frequencies are obtained using Wittrick-Williams algorithm. FEM formulation is also applied to both double and triple-walled CNTs modelled as nonlocal Euler-Bernoulli beam. The natural frequencies obtained for all the cases, are in agreement with the values provided in literature.

Some Results on Axisymmetric Vibration of Spherical Shells of Variable Thickness

1990 ◽  
Vol 112 (4) ◽  
pp. 432-437 ◽  
Author(s):  
A. V. Singh ◽  
S. Mirza
Keyword(s):  
Variable Thickness ◽  
Natural Frequencies ◽  
Mode Shapes ◽  
Axisymmetric Vibration ◽  
Spherical Shells ◽  
Varying Thickness ◽  
Wide Range

Natural frequencies and mode shapes are presented for the free axisymmetric vibration of spherical shells with linearly varying thickness along the meridian. Clamped and hinged edges corresponding to opening angles 30, 45, 60 and 90 deg have been considered in this technical brief to cover a wide range from shallow to deep spherical shells. Variations in thickness are seen to have very pronounced effects on the frequencies and mode shapes.

Maximizing the Fundamental Natural Frequency of Triangular Composite Plates

1996 ◽  
Vol 118 (2) ◽  
pp. 141-146 ◽  
Author(s):  
S. Abrate
Keyword(s):  
Natural Frequency ◽  
Material Properties ◽  
Composite Structures ◽  
Natural Frequencies ◽  
Ritz Method ◽  
Laminated Composite ◽  
Composite Plates ◽  
Mode Shapes ◽  
Fundamental Natural Frequency ◽  
Wide Range

While many advances were made in the analysis of composite structures, it is generally recognized that the design of composite structures must be studied further in order to take full advantage of the mechanical properties of these materials. This study is concerned with maximizing the fundamental natural frequency of triangular, symmetrically laminated composite plates. The natural frequencies and mode shapes of composite plates of general triangular planform are determined using the Rayleigh-Ritz method. The plate constitutive equations are written in terms of stiffness invariants and nondimensional lamination parameters. Point supports are introduced in the formulation using the method of Lagrange multipliers. This formulation allows studying the free vibration of a wide range of triangular composite plates with any support condition along the edges and point supports. The boundary conditions are enforced at a number of points along the boundary. The effects of geometry, material properties and lamination on the natural frequencies of the plate are investigated. With this stiffness invariant formulation, the effects of lamination are described by a finite number of parameters regardless of the number of plies in the laminate. We then determine the lay-up that will maximize the fundamental natural frequency of the plate. It is shown that the optimum design is relatively insensitive to the material properties for the commonly used material systems. Results are presented for several cases.

When the Rainbows Bring the Crawfish

2021 ◽  
Vol 21 (2) ◽  
pp. 90-101
Author(s):  
V. Constanza Ocampo-Raeder
Keyword(s):  
Human Nature ◽  
Social Life ◽  
Biological Diversity ◽  
River Valley ◽  
Cultural Meanings ◽  
Liminal Space ◽  
The Social ◽  
Wide Range ◽  
The Relationship

In this article I present the social life of camarones, a Peruvian river crustacean used in some of the region’s favorite dishes, and the liminal space they occupy in the geography, minds, and ecosystem of Peru and its people. I situate the relationship between these crawfish and the folks who capture them, known as camaroneros, within insights of environmental anthropologists and food scholars who also explore the connections between cultural and biological diversity and the entangled socio-ecological histories that inform the manner in which nature is mediated and understood by local societies. In this article, however, I expand this understanding to reveal unexpected spaces of engagement, especially those that emerge while eating, which tend to be overlooked by bounded notions of culture and nature and limit the ways we can imagine human-nature relationships. Via the story of camarones and camaroneros of one river valley of Peru, I argue that eating is a socio-ecological act that is imbued with profound cultural meanings involving a wide range of participants—not just farmers or producers—each with their own ecological identities yet still implicitly linked to one another through the process of producing, preparing, and consuming food.

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