103 research outputs found
Evolution of solar granulation fields from THEMIS-IPM time series
The temporal evolution of solar granulation has been investigated using a time series of high spatial and spectral resolution images acquired at the THEMIS solar telescope (Observatorio del Teide, Tenerife) using the IPM observing mode. In order to investigate different physical properties of solar granulation (associated horizontal velocity fields, lifetimes, intensity and geometry evolution), we identify and track solar granules automatically. We discuss the obtained results and compare them with results reported inthe literature. In order to overcome problems of atmospheric distortions, we also implement a FORTRAN95 code for the application of the Phase Diversity technique that is planned to be used at the
THEMIS telescope
Parameterized complexity of DPLL search procedures
We study the performance of DPLL algorithms on parameterized problems. In particular, we investigate how difficult it is to decide whether small solutions exist for satisfiability and other combinatorial problems. For this purpose we develop a Prover-Delayer game which models the running time of DPLL procedures and we establish an information-theoretic method to obtain lower bounds to the running time of parameterized DPLL procedures. We illustrate this technique by showing lower bounds to the parameterized pigeonhole principle and to the ordering principle. As our main application we study the DPLL procedure for the problem of deciding whether a graph has a small clique. We show that proving the absence of a k-clique requires n steps for a non-trivial distribution of graphs close to the critical threshold. For the restricted case of tree-like Parameterized Resolution, this result answers a question asked in [11] of understanding the Resolution complexity of this family of formulas
Artritis séptica por streptococcus pneumoniae: reporte de un caso
La artritis neumocócica es infrecuente en adultos, predomina en pacientes pediátricos. La neumonía
y la bacteriemia son las manifestaciones más frecuentes, la afectación articular según series recientes tiene
una prevalencia menor al 1% en sujetos menores de 50 años. Se presenta el caso de una paciente de 60 años con
LES (Lupus Eritematoso Sistémico) la cual presentó monoartritis séptica de rodilla derecha causada por Streptococcus
pneumoniaePneumococcal arthritis is uncommon in adults, predominantly in pediatric patients. Pneumonia
and bacteremia are the most common manifestations; joint involvement according to recent series has a lower
prevalence of 1% in subjects under 50 years. We report the case of a patient of 60 years with SLE (systemic lupus
erythematosus) which presented septic monoarthritis right knee caused by Streptococcus pneumoniae
Comment bien produire en même temps des champignons et du bois dans les forêts de pin sylvestre ? Le cas pratique de la Catalogne
La production de champignons représente une des principales richesses de nos forêts. La combinaison de la production fongique et de la production de bois est un des défis les plus importants auxquels sont confrontés les gestionnaires et les propriétaires. Ceux-ci établissent des itinéraires sylvicoles qui maximisent les bénéfices que l’on peut tirer des bois, sans compromettre leur durabilité. Cet article apporte des données sur la production de champignons, et un itinéraire sylvicole multifonctionnel est proposé qui vise à maximiser les productions conjointes de bois et de champignons au sein des peuplements réguliers de Pinus sylvestris. Les résultats définis par le Centre de la Propietat Forestal de Catalunya, avec l’assistance du Centre Tecnològic Forestal de Catalunya, se basent sur le suivi des productions fongiques de parcelles permanentes au cours des quinze dernières années. Le modèle final proposé pour la production combinée de champignons et de bois avec structure régulière prévoit une période de rotation de la coupe de 120 ans (environ 50 cm de diamètre), un régime de deux éclaircies mixtes et une densité finale de 100 pieds/ha avec régénération par éclaircies successives en deux phases
Temporal dynamics of soil fungal communities after partial and total clear-cutting in a managed Pinus sylvestris stand
Forest management aimed to maximize timber production might impact soil fungi, especially those symbiotically associated to tree roots. In this study, we analyse the temporal dynamics of soil fungi along five sampling years after tree removal in a managed Pinus sylvestris stand in northern Spain, where timber production is combined with regular mushroom harvesting. Two management methods were tested: total and partial clear-cutting leaving retention trees for seedling regeneration. Undisturbed, uncut plots were also included in the experiment as a control treatment. The whole fungal community (phylotypes and ecological guilds) were analysed by high-throughput Illumina MiSeq sequencing of fungal ITS1 amplicons. We hypothesized that (1) ectomycorrhizal fungal communities will decrease after both clear-cutting treatments with a concurrent increase in the abundance of saprotrophs, (2) the abundance and diversity of the ectomycorrhizal guild will be more preserved in partially clear-cut than in total clear-cut plots, and (3) the overall fungal diversity will decrease in the cut plots leading to major losses of ectomycorrhizal species. Our results show that soil fungal composition changed across the five years after clear-cutting by decreasing ectomycorrhizal fungi and increasing saprotrophs. However, these changes did not significantly affect fungal diversity and there were taxa-specific responses to tree harvest treatments. Boletus edulis, the most abundant ectomycorrhizal species fruiting in the study area and a valuable local non-forest resource, was negatively affected by either clear-cutting treatments. Soil fungal community composition in partially clear-cut areas was not different from that of total clear-cut areas. Our results indicate a strong effect of tree harvest on the relative abundance of ectomycorrhizal fungi along the first years after clear-cutting. However, levels of fungal diversity were comparable to the undisturbed forest, thus suggesting a potential further recovery of ectomycorrhizal fungi through the colonization of the regenerated seedlings.info:eu-repo/semantics/acceptedVersio
Finite element simulation of three-dimensional free-surface flow problems
An adaptive finite element algorithm is described for the stable solution of three-dimensional free-surface-flow problems based primarily on the use of node movement. The algorithm also includes a discrete remeshing procedure which enhances its accuracy and robustness. The spatial discretisation allows an isoparametric piecewise-quadratic approximation of the domain geometry for accurate resolution of the curved free surface.
The technique is illustrated through an implementation for surface-tension-dominated viscous flows modelled in terms of the Stokes equations with suitable boundary conditions on the deforming free surface. Two three-dimensional test problems are used to demonstrate the performance of the method: a liquid bridge problem and the formation of a fluid droplet
Chaotic differential operators
We give sufficient conditions for chaos of (differential) operators on Hilbert spaces of entire functions. To this aim we establish conditions on the coefficients of a polynomial P(z) such that P(B) is chaotic on the space lp, where B is the backward shift operator. © 2011 Springer-Verlag.This work was partially supported by the MEC and FEDER Projects MTM2007-64222, MTM2010-14909, and by GVA Project GV/2010/091, and by UPV Project PAID-06-09-2932. The authors would like to thank A. Peris for helpful comments and ideas that produced a great improvement of the paper's presentation. We also thank the referees for their helpful comments and for reporting to us a gap in Theorem 1.Conejero Casares, JA.; Martínez Jiménez, F. (2011). Chaotic differential operators. Revista- Real Academia de Ciencias Exactas Fisicas Y Naturales Serie a Matematicas. 105(2):423-431. https://doi.org/10.1007/s13398-011-0026-6S4234311052Bayart, F., Matheron, É.: Dynamics of Linear Operators, Cambridge Tracts in Mathematics, vol. 179. Cambridge University Press, Cambridge (2009)Bermúdez T., Miller V.G.: On operators T such that f(T) is hypercyclic. Integr. Equ. Oper. Theory 37(3), 332–340 (2000)Bonet J., Martínez-Giménez F., Peris A.: Linear chaos on Fréchet spaces. Int. J. Bifur. Chaos Appl. Sci. Eng. 13(7), 1649–1655 (2003)Chan K.C., Shapiro J.H.: The cyclic behavior of translation operators on Hilbert spaces of entire functions. Indiana Univ. Math. J. 40(4), 1421–1449 (1991)Conejero J.A., Müller V.: On the universality of multipliers on . J. Approx. Theory. 162(5), 1025–1032 (2010)deLaubenfels R., Emamirad H.: Chaos for functions of discrete and continuous weighted shift operators. Ergodic Theory Dyn. Syst. 21(5), 1411–1427 (2001)Devaney, R.L.: An introduction to chaotic dynamical systems, 2nd edn. In: Addison-Wesley Studies in Nonlinearity. Addison-Wesley Publishing Company Advanced Book Program, Redwood City (1989)Godefroy G., Shapiro J.H.: Operators with dense, invariant, cyclic vector manifolds. J. Funct. Anal. 98(2), 229–269 (1991)Grosse-Erdmann K.-G.: Hypercyclic and chaotic weighted shifts. Stud. Math. 139(1), 47–68 (2000)Grosse-Erdmann, K.-G., Peris, A.,: Linear chaos. Universitext, Springer, New York (to appear, 2011)Herzog G., Schmoeger C.: On operators T such that f(T) is hypercyclic. Stud. Math. 108(3), 209–216 (1994)Kahane, J.-P.: Some random series of functions, 2nd edn. In: Cambridge Studies in Advanced Mathematics, vol. 5. Cambridge University Press, Cambridge (1985)Martínez-Giménez F., Peris A.: Chaos for backward shift operators. Int. J. Bifur. Chaos Appl. Sci. Eng. 12(8), 1703–1715 (2002)Martínez-Giménez F.: Chaos for power series of backward shift operators. Proc. Am. Math. Soc. 135, 1741–1752 (2007)Müller V.: On the Salas theorem and hypercyclicity of f(T). Integr. Equ. Oper. Theory 67(3), 439–448 (2010)Protopopescu V., Azmy Y.Y.: Topological chaos for a class of linear models. Math. Models Methods Appl. Sci. 2(1), 79–90 (1992)Rolewicz S.: On orbits of elements. Stud. Math. 32, 17–22 (1969)Salas H.N.: Hypercyclic weighted shifts. Trans. Am. Math. Soc. 347(3), 93–1004 (1995)Shapiro, J.H.: Simple connectivity and linear chaos. Rend. Circ. Mat. Palermo. (2) Suppl. 56, 27–48 (1998
Melatonin affects the motility and adhesiveness of in vitro capacitated boar spermatozoa via a mechanism that does not depend on intracellular ROS levels
This work sought to address the effects of melatonin during in vitro capacitation (IVC) and progesterone-induced acrosome exocytosis (IVAE) in boar spermatozoa. With this purpose, two different experiments were set. In the first one, IVC and IVAE were induced in the absence or presence of melatonin, which was added either at the start of IVC or upon triggering the IVAE with progesterone. Different parameters were evaluated, including intracellular levels of peroxides and superoxides, free cysteine radicals and distribution of specific lectins. While melatonin neither affected most capacitation-associated parameters nor IVAE, it dramatically decreased sperm motility, with a maximal effect at 5 µm. This effect was accompanied by a significant increase in the percentage of agglutinated spermatozoa, which was independent from noticeable changes in the distribution of lectins. Levels of free cysteine radicals were significantly lower in melatonin treatments than in the control after 4 h of incubation in capacitating medium. The second experiment evaluated the effects of melatonin on in vitro fertilising ability of boar spermatozoa. Spermatozoa previously subjected to IVC in the presence of 1 µm melatonin and used for in vitro fertilisation exhibited less ability to bind the zona pellucida (ZP) and higher percentages of monospermy. In conclusion, melatonin affects sperm motility and the stability of nucleoprotein structure and also modulates the ability of in vitro capacitated boar spermatozoa to bind the oocyte ZP. However, such effects do not seem to be related to either its antioxidant properties or changes in the sperm glycocalix
Hypercyclic algebras for convolution and composition operators
[EN] We provide an alternative proof to those by Shkarin and by Bayart and Matheron that the operator D of complex differentiation supports a hypercyclic algebra on the space of entire functions. In particular we obtain hypercyclic algebras for many convolution operators not induced by polynomials, such as , , or , where . In contrast, weighted composition operators on function algebras of analytic functions on a plane domain fail to support supercyclic algebras.This work is supported in part by MEC, Project MTM 2016-7963-P. We also thank Angeles Prieto for comments and suggestions.Bès, J.; Conejero, JA.; Papathanasiou, D. (2018). Hypercyclic algebras for convolution and composition operators. Journal of Functional Analysis. 274(10):2884-2905. https://doi.org/10.1016/j.jfa.2018.02.003S288429052741
Interaction between xylanase, glucose oxidase and ascorbic acid on the technological quality of whole wheat bread
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