2,026 research outputs found
On unitary convex decompositions of vectors in a -algebra
No full textsummary:By exploiting his recent results, the author further investigates the extent to which variation in the coefficients of a unitary convex decomposition of a vector in a unital -algebra permits the vector decomposable as convex combination of fewer unitaries; certain -algebra results due to M. Rørdam have been extended to the general setting of -algebras
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Control of intraflagellar transport : studies of the planar cell polarity effector Fuz, the small GTPase Rsg1, and the novel protein TTC29
No full texttextCilia are small microtubule based protrusions found on most cells of the vertebrate body. In humans, defects in the structure or function of cilia results in a large class of developmental and homeostatic diseases known collectively as the ciliopathies. Ciliogenesis is accomplished by the concerted action of a number of molecular pathways including the intraflagellar transport (IFT) system. IFT is a group of ~20 highly conserved proteins that assemble into large macromolecular complexes known as trains. These trains act to carry cargo bi-directionally between the cell body and ciliary tip, via interaction with the microtubule motors kinesin and dynein. IFT train dynamics are required for both cilia structure and function, however the controls on these dynamics are still incompletely understood. Here, I present the first platform for study of IFT dynamics within vertebrate multiciliated cells, an understudied population with critical functions in development and homeostasis. Using this platform, I demonstrate that the planar cell polarity effector protein Fuz is required for IFT dynamics via its control of the cytoplasmic localization of a subset of IFT proteins. Subsequently, I find that a Fuz binding partner, the putative small GTPase Rsg1, is also required for IFT protein localization and dynamics. Additionally, I describe a role for Rsg1 in basal body docking, one of the earliest events of ciliogenesis. Finally, I show that the poorly studied protein TTC29 is required for a specific subset of IFT dynamic behaviors. These data reveal novel regulatory motifs for ciliogenesis and demonstrate, specifically, the complexities of IFT regulation in the cytoplasm and within the cilium itself. Finally, they suggest that multiciliated cells provide a tractable platform for generating robust datasets for the investigation ciliary dynamics. Such studies are critical for informing our understanding of the molecular etiology of human ciliopathic diseases.Cellular and Molecular BiologyPortions of Chapter 2 were modified with permission from Brooks, ER and
Wallingford, JB. Control of Vertebrate Intraflagellar Transport by the Planar Cell
Polarity Effector Fuz. J Cell Biol. (2012) 198 (1) 37-45. Portions of Chapter 3 were modified with permission from Brooks, ER and
Wallingford, JB. The small GTPase Rsg1 is important for the cytoplasmic localization
and axonemal dynamics of Intraflagellar transport proteins. Cilia (2013) 2: 13
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Climate Driven Range Shifts Impact Communities Through Altered Species Interactions
No full textClimate change is likely the greatest threat to global biodiversity and ecosystem functioning, and it is becoming increasingly apparent that understanding the effects of climate change requires going beyond single species or limited spatial scales. Climate change will impact species and communities through both direct and indirect effects, as mediated by species interactions, and incorporating these indirect effects can increase the ability to track shifting species distributions. I used a space-for-time approach to test if incorporating indirect effects increases predictive ability through surveys of vertical distributions of predators (sea stars) and prey species (mussels) spanning a thermal gradient along the West Coast. Prey distributions were directly influenced by temperature, but there was also a significant indirect effect of temperature, as mediated by predator distributions. Under future climate change, mussel ranges may undergo vertical shifts towards subtidal habitats, allowing for localized persistence of mussels and their associated species. However, both local and broad scale range-shifts can displace other species or alter community and ecosystem processes. Despite inherent differences between introduced and range-shifting species, impacts can occur via analogous mechanisms, and the magnitude of impacts can be similar. Risk assessments developed for invasive species provide a useful tool for assessing potential impacts of range-shifting species. Altered species interactions and communities can be observed locally in southern California intertidal communities, where the whelk Mexacanthina lugubris is undergoing a northward range shift. I assessed the impacts of Mexacanthina on local species, through long-term field surveys, coupled with manipulative experiments to assess current and future impacts on competitors. Mexacanthina is now well established and utilizes analogous resources and habitats as native whelk species. Mexacanthina can also survive at warmer temperatures than native whelks, suggesting that range-shifters may have a competitive advantage in a warming climate. The persistence of some species at the expense of others underscores the complexities of conservation in the era of climate change. My thesis research explores this dichotomy by examining how species interactions can indirectly alter distributions (Ch. 1), which traits are indicative of problematic range-shifters (Ch. 2), and how a range-shifting species is altering southern California communities (Ch. 3)
Decoupling and prices: determinant of dairy farmers’ choices? A model to analyse impacts of the 2003 CAP reform
No full textThe reform of European Common Agricultural Policy (CAP) in 2003 has resulted in substantial changes to the attribution of subsidies to dairy farmers. Moreover, dairy farmers are in also facing an unprecedented situation on the markets with the soaring prices of agricultural raw materials: they sell their products at a higher price (milk, meat and cereals), but must also cope with the increasing prices of concentrates. In this paper1, we discuss cross effects, on the productive strategy of French dairy farms, of the Luxemburg Agreement and the prices variations. A model based on mathematical programming has been privileged to determine how dairy farmers might re-evaluate their systems to identify optimal production plan. While respecting the principle of agent rationality (maximization of profit), the model incorporates the economic risk related to the volatility of the inputs and outputs prices. Thus the model maximises the expected utility of the income while taking into account a set of constraints: regulatory, structural, zootechnical, agronomic and environmental. The model is applied to four types of dairy farms to cope with the diversity of production systems in the west of France (“grazier” type, “semi intensive” type, “milk + cereals” type and “milk + young bulls” type). The model is used to produce quantitative estimations and support reflection through the simulation of the setting up of the Single payment scheme. The sensitivity of the results is discussed by taking into account several options of prices for cereals and livestock products. These may have a strong influence on the structure of the diet and, therefore, on the level of intensification of the forage area. The results show that the implementation of the CAP reform encourages farmers to substitute a part of corn silage by grass in the diet. However, the rising price of agricultural production encourages, on the contrary, farmers to intensify their system in order to free up land for growing cereals. We also observe that a decrease of the young bulls fattening activity to develop cereal crops is also economically profitable.dairy farm, single payment, price variation, Agricultural and Food Policy, Livestock Production/Industries,
Erratum: Half-supersymmetric solutions in five-dimensional supergravity (Journal of High Energy Physics (2007) 12 (025))
No full text[No abstract available]Gutowski JB, 2007, J HIGH ENERGY PHYS11
Surjective isometries between unitary sets of unital JB∗-algebras
No full textWe would like to thank Prof. Lajos Molnár for encouraging us to explore this problem.
We are also indebted to the anonymous reviewer for several useful comments.
First and fifth authors partially supported by the Spanish Ministry of Science, Innovation and Universities (MICINN) and European Regional Development Fund project
no. PGC2018-093332-B-I00, Programa Operativo FEDER 2014-2020 and Consejería de
Economía y Conocimiento de la Junta de Andalucía grant numbers A-FQM-242-UGR18
and FQM375. First author partially supported by EPSRC (UK) project “Jordan Algebras, Finsler Geometry and Dynamics” ref. no. EP/R044228/1. Second author partially
supported by JSPS KAKENHI Grant Number JP 21J21512. Fourth author partially
supported by JSPS KAKENHI (Japan) Grant Number JP 20K03650.
* Funding for open access charge: Universidad de Granada / CBUAThis paper is, in a first stage, devoted to establishing a topological–algebraic characterization of the principal component, U0(M), of the set of unitary elements, U(M), in a unital JB⁎-algebra M. We arrive to the conclusion that, as in the case of unital C⁎-algebras, U0(M)=M1−1∩U(M)={Ue⋯Ue(1):n∈N,hj∈Msa∀1≤j≤n}={u∈U(M): there exists w∈U0(M) with ‖u−w‖<2} is analytically arcwise connected. Actually, U0(M) is the smallest quadratic subset of U(M) containing the set eiM. Our second goal is to provide a complete description of the surjective isometries between the principal components of two unital JB⁎-algebras M and N. Contrary to the case of unital C⁎-algebras, we shall deduce the existence of connected components in U(M) which are not isometric as metric spaces. We shall also establish necessary and sufficient conditions to guarantee that a surjective isometry Δ:U(M)→U(N) admits an extension to a surjective linear isometry between M and N, a conclusion which is not always true. Among the consequences it is proved that M and N are Jordan ⁎-isomorphic if, and only if, their principal components are isometric as metric spaces if, and only if, there exists a surjective isometry Δ:U(M)→U(N) mapping the unit of M to an element in U0(N). These results provide an extension to the setting of unital JB⁎-algebras of the results obtained by O. Hatori for unital C⁎-algebras.CBUAConsejería de Economía y Conocimiento de la Junta de Andalucía
A-FQM-242-UGR18, FQM375Ministerio de Ciencia, Innovación y UniversidadesEngineering and Physical Sciences Research Council
EP/R044228/1Universidad de GranadaMinisterio de Ciencia e InnovaciónJapan Society for the Promotion of Science JP 20K03650, JP 21J21512European Regional Development Fund
PGC2018-093332-B-I0
Flexible time–space network formulation and hybrid metaheuristic for conflict-free and energy-efficient path planning of automated guided vehicles
No full textOperations of Automated Guided Vehicles (AGVs) are desired to be more energy-efficient while maintaining high transport productivity, motivated by the green production requirements. This paper investigates a new energy-efficient planning problem for determining conflict-free paths of the AGVs in its transport roadmap. In this problem, the vehicle path and transport time in the roadmap are jointly optimized, based on a flexible time–space network (FTSN). We provide the mathematical problem formulation of the energy-efficient path planning problem. The resulting optimization problem is proved to be a non-convex mixed-integer nonlinear programming which is computationally intractable. We further propose a hybrid metaheuristic that integrates the genetic algorithm and estimation of the distribution algorithm to improve its computational efficiency. Numerical results show the effectiveness of the developed algorithm based on the FTSN framework, compared to the existing metaheuristics, the conventional path planning method, and a commercial solver. The proposed method has a wide application in improving energy use of material handling, providing a guiding significance on promoting cleaner production of flexible manufacturing systems.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic
Decoupling of genome size and sequence divergence in a symbiotic bacterium
No full textAuthor Posting. © American Society for Microbiology, 2000. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Journal of Bacteriology 182 (2000): 3867-3869, doi:10.1128/JB.182.13.3867-3869.2000.In contrast to genome size variation in most bacterial taxa, the small genome size of Buchnera sp. was shown to be highly conserved across genetically diverse isolates (630 to 643 kb). This exceptional size conservation may reflect the inability of this obligate mutualist to acquire foreign DNA and reduced selection for genetic novelty within a static intracellular environment.Financial support was provided by a National Institute of Health
postdoctoral training grant to J.J.W. (Center for Insect Science, University
of Arizona) and a National Science Foundation grant (DEB-
9815413) to N.A.M
Vertical transmission of biosynthetic plasmids in aphid endosymbionts (Buchnera)
No full textAuthor Posting. © American Society for Microbiology, 2001. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Journal of Bacteriology 183 (2001): 785-790, doi:10.1128/JB.183.2.785-790.2001.This study tested for horizontal transfer of plasmids among Buchnera aphidicola strains associated with
ecologically and phylogenetically related aphid hosts (Uroleucon species). Phylogenetic congruence of Buchnera
plasmid (trpEG and leuABC) and chromosomal (dnaN and trpB) genes supports strictly vertical long-term transmission
of plasmids, which persist due to their contributions to host nutrition rather than capacity for infectious
transfer. Synonymous divergences indicate elevated mutation on plasmids relative to chromosomal genes.This work was supported by a National Institutes of Health postdoctoral
training grant in Molecular Insect Science (Center for Insect
Science, University of Arizona) to J.J.W. and a National Science Foundation
grant (DEB-9815413) to N.A.M
Tn5 synaptic complex formation : role of transposase residue W450
No full textAuthor Posting. © American Society for Microbiology, 2008. This article is posted here by permission of American Society for Microbiology for personal use, not for redistribution. The definitive version was published in Journal of Bacteriology 190 (2008): 1484-1487, doi:10.1128/JB.01488-07.A series of Tn5 transposases (Tnp's) with mutations at the conserved amino acid position W450, which was structurally predicted to be important for synapsis, have been generated and characterized. This study demonstrates that W450 is involved in hydrophobic (and possibly aromatic) contacts within the Tnp monomer that negatively regulate synaptic complex formation.This work was supported by the NIH (grant no. GM50693) and the University of Wisconsin—Madison (grant no. WIS04792) and through the Evelyn Mercer Professorship in Biochemistry and Molecular Biology
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