18 research outputs found
{\phi}^4 Solitary Waves in a Parabolic Potential: Existence, Stability, and Collisional Dynamics
We explore a {\phi}^4 model with an added external parabolic potential term.
This term dramatically alters the spectral properties of the system. We
identify single and multiple kink solutions and examine their stability
features; importantly, all of the stationary structures turn out to be
unstable. We complement these with a dynamical study of the evolution of a
single kink in the trap, as well as of the scattering of kink and anti-kink
solutions of the model. We see that some of the key characteristics of
kink-antikink collisions, such as the critical velocity and the multi-bounce
windows, are sensitively dependent on the trap strength parameter, as well as
the initial displacement of the kink and antikink
Stringy instanton effects in N=2 gauge theories
We study the non-perturbative effects induced by stringy instantons on N=2
SU}(N) gauge theories in four dimensions, realized on fractional D3 branes in a
C^3/Z_3 orientifold. The stringy instantons, corresponding to D(-1) branes that
occupy a node of the orientifold quiver diagram where no D3 brane is present,
have the right content of zero-modes to produce non-perturbative terms in the
four-dimensional effective action. In the SU(2) theory these terms have the
same structure for all instanton numbers and yield a series of non-perturbative
corrections to the prepotential. We explicitly compute these corrections up to
instanton number k=5 using localization methods.Comment: 31 pages, 1 figure, PdfLaTe
Ocean acidification and temperature rise: effects on calcification during early development of the cuttlefish Sepia officinalis
This study investigated the effects of seawater pH (i.e., 8.10, 7.85 and 7.60) and temperature (16 and 19 °C) on (a) the abiotic conditions in the fluid surrounding the embryo (viz. the perivitelline fluid), (b) growth, development and (c) cuttlebone calcification of embryonic and juvenile stages of the cephalopod Sepia officinalis. Egg swelling increased in response to acidification or warming, leading to an increase in egg surface while the interactive effects suggested a limited plasticity of the swelling modulation. Embryos experienced elevated pCO2 conditions in the perivitelline fluid (>3-fold higher pCO2 than that of ambient seawater), rendering the medium under-saturated even under ambient conditions. The growth of both embryos and juveniles was unaffected by pH, whereas 45Ca incorporation in cuttlebone increased significantly with decreasing pH at both temperatures. This phenomenon of hypercalcification is limited to only a number of animals but does not guarantee functional performance and calls for better mechanistic understanding of calcification processes
Semiclassical description of soliton-antisoliton pair production in particle collisions
Role of antioxidant enzymes and small molecular weight antioxidants in the pathogenesis of age-related macular degeneration (AMD)
Current Status and Future Challenges in Cephalopod Culture
11 pagesThis chapter presents an overall perspective on the current status of cephalopod culture, its bottlenecks and future challenges. It focuses on the species that have received more research effort and consequently accumulated more scientific literature during the present century, namely Sepia officinalis, Sepioteuthis lessoniana, Octopus maya and Octopus vulgaris. Knowledge regarding physiology, metabolism and nutrition of different species is still lacking. Two main challenges are identified: the development of a sustainable artificial diet and the control of reproduction. Understanding cephalopod physiology and nutrition will probably be the biggest challenge in developing the large-scale culture of this group of molluscs on a medium to long term. In addition, zootechnical parameters need future research and improvement. The performance of an ethical experimentation with cephalopods is strongly encouraged and any zootechnical development should be performed and adapted accordingly. The potential of cephalopod culture extends far beyond its use for research and human consumption and probably it will be translated in a remarkable production in the coming yearsThis chapter presents an overall perspective on the current status of cephalopod culture, its bottlenecks and future challenges. It focuses on the species that have received more research effort and consequently accumulated more scientific literature during the present century, namely Sepia officinalis, Sepioteuthis lessoniana, Octopus maya and Octopus vulgaris. Knowledge regarding physiology, metabolism and nutrition of different species is still lacking. Two main challenges are identified: the development of a sustainable artificial diet and the control of reproduction. Understanding cephalopod physiology and nutrition will probably be the biggest challenge in developing the large-scale culture of this group of molluscs on a medium to long term. In addition, zootechnical parameters need future research and improvement. The performance of an ethical experimentation with cephalopods is strongly encouraged and any zootechnical development should be performed and adapted accordingly. The potential of cephalopod culture extends far beyond its use for research and human consumption and probably it will be translated in a remarkable production in the coming yearsPeer reviewe