639 research outputs found
Efeito do consórcio de braquiária com crotalária na multiplicação de Pratylenchus brachyurus.
Overlooked gall-inducing moths revisited, with the description of Andescecidium parrai gen. et sp. n. and Oliera saizi sp. n. from Chile (Lepidoptera, Cecidosidae)
There are still many gall systems associated with larvae of Lepidoptera in which the true gall-inducers have not been identified to species. Reports on misidentification of gall inducers have been recurrent for these galls, particularly in complex gall-systems that may include inquilines, kleptoparasites, and cecidophages, among other feeding guilds such as predators and parasitoid wasps. Here we describe and illustrate the adults, larvae, pupae and galls, based on light and scanning microscopy, of Andescecidium parrai gen. et sp. n. and Oliera saizi sp. n., two sympatric cecidosid moths that are associated with Schinus polygamus (Cav.) Cabrera (Anacardiaceae) in central Chile. Adults, immatures, and galls of the former did not conform to any known cecidosid genus. Galls of A. parrai are external, spherical, and conspicuous, being known for more than one century. However, their induction has been mistakenly associated with either unidentified Coleoptera (original description) or Oliera argentinana Br糨es (recently), a distinct cecidosid species with distribution restricted to the eastern Andes. Galls of O. saizi had been undetected, as they are inconspicuous. They occur under the bark within swollen stems, and may occur on the same plant, adjacent to those of A. parrai. We also propose a time-calibrated phylogeny using sequences from mitochondrial and nuclear loci, including specimens of the new proposed taxa. Thus in addition to clarifying the taxonomy of the Chilean cecidosid species we also tested their monophyly in comparison to congeneric species and putative specimens of all genera of Neotropical and African cecidosids.Fil: Silva, Gabriela T.. Universidade Federal do Rio Grande do Sul; BrasilFil: Moreira, Gilson R. P.. Universidade Federal do Rio Grande do Sul; BrasilFil: Vargas, Héctor A.. Universidad de Tarapacá de Arica; ChileFil: Gonçalves, Gislene L.. Universidade Federal do Rio Grande do Sul; Brasil. Universidad de Tarapacá de Arica; ChileFil: Mainardi, Marina D.. Universidade Federal do Rio Grande do Sul; BrasilFil: San Blas, Diego German. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Pampa; ArgentinaFil: Davis, Donald. National Museum of Natural History; Estados Unido
Uncoupled continuous-time random walks: Solution and limiting behavior of the master equation
A detailed study is presented for a large class of uncoupled continuous-time
random walks (CTRWs). The master equation is solved for the Mittag-Leffler
survival probability. The properly scaled diffusive limit of the master
equation is taken and its relation with the fractional diffusion equation is
discussed. Finally, some common objections found in the literature are
thoroughly reviewed.Comment: Preprint version of an already published paper. 8 page
A multivariate time-frequency method to characterize the influence of respiration over heart period and arterial pressure
Respiratory activity introduces oscillations both in arterial pressure and heart period, through mechanical and autonomic mechanisms. Respiration, arterial pressure, and heart period are, generally, non-stationary processes and the interactions between them are dynamic. In this study we present a methodology to robustly estimate the time course of cross spectral indices to characterize dynamic interactions between respiratory oscillations of heart period and blood pressure, as well as their interactions with respiratory activity. Time-frequency distributions belonging to Cohen's class are used to estimate time-frequency (TF) representations of coherence, partial coherence and phase difference. The characterization is based on the estimation of the time course of cross spectral indices estimated in specific TF regions around the respiratory frequency. We used this methodology to describe the interactions between respiration, heart period variability (HPV) and systolic arterial pressure variability (SAPV) during tilt table test with both spontaneous and controlled respiratory patterns. The effect of selective autonomic blockade was also studied. Results suggest the presence of common underling mechanisms of regulation between cardiovascular signals, whose interactions are time-varying. SAPV changes followed respiratory flow both in supine and standing positions and even after selective autonomic blockade. During head-up tilt, phase differences between respiration and SAPV increased. Phase differences between respiration and HPV were comparable to those between respiration and SAPV during supine position, and significantly increased during standing. As a result, respiratory oscillations in SAPV preceded respiratory oscillations in HPV during standing. Partial coherence was the most sensitive index to orthostatic stress. Phase difference estimates were consistent among spontaneous and controlled breathing patterns, whereas coherence was higher in spontaneous breathing. Parasympathetic blockade did not affect interactions between respiration and SAPV, reduced the coherence between SAPV and HPV and between respiration and HPV. Our results support the hypothesis that non-autonomic, possibly mechanically mediated, mechanisms also contributes to the respiratory oscillations in HPV. A small contribution of sympathetic activity on HPV-SAPV interactions around the respiratory frequency was also observed
Quantification of Spatial Repolarization Heterogeneity: Testing the Robustness of a New Technique
Abstract The V-index is a recently-proposed metric related to repolarization heterogeneity (RH) Introduction Spatial heterogeneity of ventricular repolarization is a key quantity for the development of arrhythmias. Despite many methods have been proposed and investigated in the past [1-3], a non-invasive quantification of Repolarization Heterogeneity (RH) is still an open issue We recently proposed an estimator of the standard deviation of RH, which was named "V-index" Although the performances of the method have been deeply investigated in the original paper Method An estimate of repolarization heterogeneity Let us suppose to subdivide the myocardium in "nodes", each node m sharing a common transmembrane potential (TMP), D(t), but having a specific repolarization time given by ρ m =ρ + Δρ m . At each node m, the repolarization delay Δρ m is the deviation from the average repolarization timeρ = 1 M M m=1 ρ m in the given heartbeat. We have recently [5] introduced a simple model to describe the distribution of these delays Δρ m (k) among beats, being k the beat index. In particular we set: where ϑ m models the spatial variability of the repolarization times for a given subject at a given HR, and ϕ m (k) describes difference in repolarization times which are observable among successive beats
On a initial value problem arising in mechanics
We study initial value problem for a system consisting of an integer order
and distributed-order fractional differential equation describing forced
oscillations of a body attached to a free end of a light viscoelastic rod.
Explicit form of a solution for a class of linear viscoelastic solids is given
in terms of a convolution integral. Restrictions on storage and loss moduli
following from the Second Law of Thermodynamics play the crucial role in
establishing the form of the solution. Some previous results are shown to be
special cases of the present analysis
Lebesgue regularity for differential difference equations with fractional damping
We provide necessary and sufficient conditions for the existence and unique-ness of solutions belonging to the vector-valued space of sequences �(Z, X) forequations that can be modeled in the formΔu(n)+Δu(n)=Au(n)+G(u)(n)+ (n), n ∈ Z,,>0,≥0,where X is a Banach space, ∈ �(Z, X), A is a closed linear operatorwith domain D(A) defined on X,andG is a nonlinear function. The oper-ator Δdenotes the fractional difference operator of order >0inthesense of Grünwald-Letnikov. Our class of models includes the discrete timeKlein-Gordon, telegraph, and Basset equations, among other differential differ-ence equations of interest. We prove a simple criterion that shows the existenceof solutions assuming that f is small and that G is a nonlinear term
Effect of Extra Lesions on AF Burden of Continuously Monitored Patients Undergoing Single-Procedure Catheter Ablation. Abstract
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