The oblique firehose instability in a bi-kappa magnetized plasma

In this work, we derive a dispersion equation that describes the excitation of the oblique (or Alfv\'en) firehose instability in a plasma that contains both electron and ion species modelled by bi-kappa velocity distribution functions. The equation is obtained with the assumptions of low-frequency waves and moderate to large values of the parallel (respective to the ambient magnetic field) plasma beta parameter, but it is valid for any direction of propagation and for any value of the particle gyroradius (or Larmor radius). Considering values for the physical parameters typical to those found in the solar wind, some solutions of the dispersion equation, corresponding to the unstable mode, are presented. In order to implement the dispersion solver, several new mathematical properties of the special functions occurring in a kappa plasma are derived and included. The results presented here suggest that the superthermal characteristic of the distribution functions leads to reductions to both the maximum growth rate of the instability and of the spectral range of its occurrence

Carbon stars in the X-shooter Spectral Library

We provide a new collection of spectra of 35 carbon stars obtained with the ESO/VLT X-shooter instrument as part of the X-shooter Spectral Library project. The spectra extend from 0.3$\mu$m to 2.4$\mu$m with a resolving power above $\sim$ 8000. The sample contains stars with a broad range of (J-K) color and pulsation properties located in the Milky Way and the Magellanic Clouds. We show that the distribution of spectral properties of carbon stars at a given (J-K) color becomes bimodal (in our sample) when (J-K) is larger than about 1.5. We describe the two families of spectra that emerge, characterized by the presence or absence of the absorption feature at 1.53$\mu$m, generally associated with HCN and C$_2$H$_2$. This feature appears essentially only in large-amplitude variables, though not in all observations. Associated spectral signatures that we interpret as the result of veiling by circumstellar matter, indicate that the 1.53$\mu$m feature might point to episodes of dust production in carbon-rich Miras.Comment: 29 pages, 21 figures, 9 tables, Accepted for publication in A&

Abelian subgroups of Garside groups

In this paper, we show that for every abelian subgroup $H$ of a Garside group, some conjugate $g^{-1}Hg$ consists of ultra summit elements and the centralizer of $H$ is a finite index subgroup of the normalizer of $H$. Combining with the results on translation numbers in Garside groups, we obtain an easy proof of the algebraic flat torus theorem for Garside groups and solve several algorithmic problems concerning abelian subgroups of Garside groups.Comment: This article replaces our earlier preprint "Stable super summit sets in Garside groups", arXiv:math.GT/060258

Bidirectional flow of action potentials in axons drives activity dynamics in neuronal cultures

Objective. Recent technological advances are revealing the complex physiology of the axon and challenging long-standing assumptions. Namely, while most action potential (AP) initiation occurs at the axon initial segment in central nervous system neurons, initiation in distal parts of the axon has been reported to occur in both physiological and pathological conditions. The functional role of these ectopic APs, if exists, is still not clear, nor its impact on network activity dynamics. Approach. Using an electrophysiology platform specifically designed for assessing axonal conduction we show here for the first time regular and effective bidirectional axonal conduction in hippocampal and dorsal root ganglia cultures. We investigate and characterize this bidirectional propagation both in physiological conditions and after distal axotomy. Main results. A significant fraction of APs are not coming from the canonical synapse-dendrite-soma signal flow, but instead from signals originating at the distal axon. Importantly, antidromic APs may carry information and can have a functional impact on the neuron, as they consistently depolarize the soma. Thus, plasticity or gene transduction mechanisms triggered by soma depolarization can also be affected by these antidromic APs. Conduction velocity is asymmetrical, with antidromic conduction being slower than orthodromic. Significance. Altogether these findings have important implications for the study of neuronal function in vitro, reshaping our understanding on how information flows in neuronal cultures.info:eu-repo/semantics/publishedVersio

Desenvolvimento de cebolinha sob diferentes doses de esterco de curral associado à adubação mineral.

O objetivo desse trabalho foi avaliar doses de esterco bovino associado à adubação mineral sobre o rendimento de cebolinha (Allium fistulosum L). O experimento foi conduzido no DTCS-UNEB, Juazeiro ? BA, por um período de 52 dias. Os tratamentos constaram de 05 doses de esterco bovino (0,0; 2,5; 5,0; 10,0 e 15,0 L m -2 ) na presença de adubo mineral ? uréia, superfosfato siples e cloreto de potássio, em quatro repetições. O delineamento estatístico utilizado foi o inteiramente casualizado. Os resultados obtidos demonstram que houve mudanças nas propriedades químicas do solo (aumento de pH, redução na acidez potencial, aumento da CTC) com a utilização de esterco bovino. Os tratamentos que receberam 2,5 e 5,0 L esterco m -2 apresentaram as melhores médias para as variáveis peso seco da parte aérea, número de folhas e número de perfilhos. As mudanças nas propriedades químicas do solo não foram suficientes para promover mudanças significativas nas variáveis agronômicas avaliadas.Edição dos resumos expandidos do 45. Congresso Brasileiro de Olericultura; 15 Congresso Brasileiro de Floricultura e Plantas Ornamentais; 2. Congresso Brasileiro de Cultura de Tecidos de Plantas, Fortaleza, ago. 2005. 1 CD-ROM

Proposta de um sistema hierárquico de classificação de cobertura da terra baseado na análise de imagens de satélite.

ABSTRACT -Land cover maps are essential to conduct programs of environmental monitoring, biodiversity conservation and land occupation. In Brazil, there are no specific rules to guide the development of such maps. Consequently, there is a tendency of each institution to create its own system to attend its specific needs. This study presents a new land cover classification system based on a single date, multispectral Landsat image and suitable for scales varying from 1.1,000,000 to 1:100,000. Visual image interpretation and field inspection allowed the identification of four spectral land cover classes at the 1:1,000,000 scale: water bodies, natural vegetation covers, planted vegetation covers, constructed surfaces and others. At the 1:500,000, 1:250,000 and 1:100,000 scales, these classes were splited into 10, 19 and 22 subclasses, respectively. Results showed that the Landsat imagery is useful for land cover mapping proposals in the exploratory, surveying and semidetailed level

Atlaspix3: A high voltage CMOS sensor chip designed for ATLAS Inner Tracker

ATLASpix3 is a 2 x 2 cm$^{2}$ high voltage CMOS sensor chip designed to meet the specifications of outer layers of ATLAS inner tracker. It is compatible with the hybrid pixel sensor ASIC RD53A in terms of electronic interface and geometry. ATLASpix3 is a depleted monolithic CMOS pixel detector which allows the construction of quad modules of the same size as that of hybrid sensors. The readout scheme can be externally configured as triggered or triggerless column drain readout. The hit information is transmitted through a 1.28 Gbit/s serial link. The interface is based on a single command input that is used for providing clock, trigger and configuration commands. This contribution summarizes the detector architecture with focus on the design of its readout circuitry. In addition, simulation results obtained using ReadOut Modelling Environment (ROME), that led to the design of the readout system are discussed