Search results for "Theorem"

A Characterization of Quintic Helices

2005

A polynomial curve of degree 5, @a, is a helix if and only if both @[email protected]^'@? and @[email protected]^'@[email protected]^''@? are polynomial functions.

Population structure and reticulate evolution of Saccharomyces eubayanus and its lager-brewing hybrids

2014

Reticulate evolution can be a major driver of diversification into new niches, especially in disturbed habitats and at the edges of ranges. Industrial fermentation strains of yeast provide a window into these processes, but progress has been hampered by a limited understanding of the natural diversity and distribution of Saccharomyces species and populations. For example, lager beer is brewed with Saccharomyces pastorianus, an alloploid hybrid of S. cerevisiae and S. eubayanus, a species only recently discovered in Patagonia, Argentina. Here, we report that genetically diverse strains of S. eubayanus are readily isolated from Patagonia, demonstrating that the species is well established the…

Bifurcation phenomena for the positive solutions of semilinear elliptic problems with mixed boundary conditions

2016

We consider a parametric semilinear elliptic equation with a Cara-theodory reaction which exhibits competing nonlinearities. It is "concave" (sub-linear) near the origin and "convex" (superlinear) or linear near $+\infty$. Using variational methods based on the critical point theory, coupled with suitable truncation and comparison techniques, we prove a bifurcation-type theorem, describing the set of positive solutions as the parameter varies.

Design of a solar-battery-thermoelectric power converter prototype

2015

In this paper a multisource renewable energy system for high-current applications is proposed. The power architecture is based on a multi-input power converter including control and reconfiguration subsystems. Independently of the type of connected renewable sources, a proper control of the output DC voltage bus is provided as well as a proper control on the operating point of each renewable source to achieve the maximum power transfer. A 48V thermoelectric-photovoltaic-battery system in a three input configuration is designed. Three interacting feedback networks are implemented: the outer loop which controls the output voltage and as many inner loops as connected renewable sources to achie…

A rank theorem for analytic maps between power series spaces

1994

Phylogenetic relationship among genera of Polymorphidae (Acanthocephala), inferred from nuclear and mitochondrial gene sequences.

2013

Abstract Acanthocephalans of the family Polymorphidae Meyer, 1931 are obligate endoparasites with complex life cycles. These worms use vertebrates (marine mammals, fish-eating birds and waterfowl) as definitive hosts and invertebrates (amphipods, decapods and euphausiids) as intermediate hosts to complete their life cycle. Polymorphidae has a wordwide distribution, containing 12 genera, with approximately 127 species. The family is diagnosed by having a spinose trunk, bulbose proboscis, double-walled proboscis receptacle, and usually four to eight tubular cement glands. To conduct a phylogenetic analysis, in the current study sequences of the small (18S) and large-subunit (28S) ribosomal RN…

groups acting on the line and the circle with at most N fixed points

2022

A classical theme in dynamical systems is that the first fundamental information comes from the understanding of periodic orbits. When studying group actions, this means that we want to understand the fixed points of elements of the group, and a natural question that emerges from that is: Which groups of homeomorphisms can act on a 1-manifold having all non-trivial elements with at most N fixed points? Our main objective in this work is to approach that question and understand what properties can such dynamical hypothesis induces to the group.For the case N=0, a classical result from O. Hölder implies that such group of homeomorphisms acting on the line is always semi-conjugate to a subgrou…

CiliaCarta: An integrated and validated compendium of ciliary genes

2019

The cilium is an essential organelle at the surface of mammalian cells whose dysfunction causes a wide range of genetic diseases collectively called ciliopathies. The current rate at which new ciliopathy genes are identified suggests that many ciliary components remain undiscovered. We generated and rigorously analyzed genomic, proteomic, transcriptomic and evolutionary data and systematically integrated these using Bayesian statistics into a predictive score for ciliary function. This resulted in 285 candidate ciliary genes. We generated independent experimental evidence of ciliary associations for 24 out of 36 analyzed candidate proteins using multiple cell and animal model systems (mouse…

Study on the Effects of Pseudorandom Generation Quality on the Performance of Differential Evolution

2011

Experiences in the field of Monte Carlo methods indicate that the quality of a random number generator is exceedingly significant for obtaining good results. This result has not been demonstrated in the field of evolutionary optimization, and many practitioners of the field assume that the choice of the generator is superfluous and fail to document this aspect of their algorithm. In this paper, we demonstrate empirically that the requirement of high quality generator does not hold in the case of Differential Evolution.

Considerations on correlations in shift-register pseudorandom number generators and their removal

1997

Abstract We present a simple calculation quantitatively explaining the triplet correlations in the popular shift-register random number generator “R250”, which were recently observed numerically by Schmid and Wilding, and are known from general analysis of this type of generator. Starting from these considerations, we discuss various methods to remove these correlations by combining different shift-register generators. We implement and test a particularly simple and fast version, based on an XOR combination of two independent shift-register generators with different time lags. The results indicate that this generator has much better statistical properties than R250, while being only a facto…