Vertical distribution of earthworms in grassland soils of the Colombian Llanos

The vertical distribution of native earthworm species from natural and disturbed savannas in the Oxisols of the Colombian Llanos was assessed in a native savanna and in a 17-year-old grazed grass-legume pasture during a period of 17 months. Different patterns of vertical stratification were observed for all species with a strong migration of populations to deeper layers in the dry season. The correlation between the size of the earthworms and the average depth at which they were found was not significant (P>0.05), despite the fact that bigger species are located deeper in the soil. The living habits and adaptive strategies of the smallest species, Ocnerodrilidae n. sp., found in both ecosystems studied are responsible for this pattern. This endogeic species is associated with organic pools generated by an anecic species and further studies should assess the role of this species in ecosystem functioning. Mature worms of one anecic species were located deeper than immature ones in the soil (P<0.01). Soil moisture had an important effect on the vertical distribution of earthworms, although differences between immature and mature worms of the anecic Martiodrilus carimaguensis are likely to be of biotic origin. New data on the biology and ecology of these Neotropical species are shown.This work was carried out within a research grant of the Macrofauna project (EC - STD2). We want to thank Professor Patrick Lavelle (IRD, France), and Drs. Richard J Thomas and Myles J Fisher (International Center for Tropical Agriculture, CIAT, Colombia) for their encouragement and enthusiasm to study the role of earthworms in the savannas and man-made pastures of Carimagua, in the Colombian “Llanos”. The first author would like to thank Jean Pierre Rossi (IRD, France) and two anonymous referees for helpful comments and their criticism on a first version draft of this paper.Peer reviewe

Is 6-Li in metal-poor halo stars produced in situ by solar-like flares ?

The high 6-Li abundances recently measured in metal-poor halo stars are far above the value predicted by Big Bang nucleosynthesis. They cannot be explained by galactic cosmic-ray interactions in the interstellar medium either. Various pre-galactic sources of 6-Li have been proposed in the literature. We study the possibility that the observed 6-Li was produced by repeated solar-like flares on the main sequence of these low-metallicity stars. The time-dependent flaring activity of these objects is estimated from the observed evolution of rotation-induced activity in Pop I dwarf stars. As in solar flares, 6-Li could be mainly created in interactions of flare-accelerated 3-He with stellar atmospheric 4-He, via the reaction 4-He(3-He,p)6-Li. Stellar dilution and destruction of flare-produced 6-Li are evaluated from the evolutionary models of metal-poor stars developed by Richard and co-workers. Stellar depletion should be less important for 6-Li atoms synthesized in flares than for those of protostellar origin. Theoretical frequency distributions of 6-Li/7-Li ratios are calculated using a Monte-Carlo method and compared with the observations. Excellent agreement is found with the measured 6-Li/7-Li distribution, when taking into account the contribution of protostellar 6-Li originating from galactic cosmic-ray nucleosynthesis. We propose as an observational test of the model to seek for a positive correlation between 6-Li/7-Li and stellar rotation velocity. We also show that the amounts of 7-Li, Be and B produced in flares of metal-poor halo stars are negligible as compared with the measured abundances of these species. 6-Li in low-metallicity stars may be a unique evidence of the nuclear processes occuring in stellar flares

A new genus of Hypogastruridae (Insecta: Collembola) in Amazonia

Description of a new genus of Collembola (Insecta), Hypogastruridae family, edaphic of Amazonian - Amazonas (Brazil), near the genus Willemia and Acherontides: Willemgastrura coeca. n.g., n. sp

Alternative Substrates and Fertilization Routine Relationships for Bedding Pot Plants: Impatiens wallerana

This study was carried out searching for alternative substrates to traditional peat based on river waste and Sphagnum and Carex peat from Argentinean peatlands and used to grow Impatiens wallerana bedding plant. The aim of this study was i) to characterize physical and chemical effects from seven growing media on I. wallerana plants grown under different fertilization rates and ii) to describe the physiological mechanisms in plants, involved in the use of such substrates. Particle stability was lower for the six alternative substrates compared to the Canadian peat-base control substrate. However, with a high fertilization dose it is possible to reach non significant differences in plant growth compared to the control substrate. It is suggested, for future research, that nitrogen signalling associated to cytokinin synthesis by roots is involved.Fil: Thibaud, J.. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Vegetal. Cátedra de Floricultura; ArgentinaFil: Loughlin, T. Mc.. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Vegetal. Cátedra de Floricultura; ArgentinaFil: Pagani, A.. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Vegetal. Cátedra de Floricultura; ArgentinaFil: Lavado, Raul Silvio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales. Universidad de Buenos Aires. Facultad de Agronomía. Instituto de Investigaciones en Biociencias Agrícolas y Ambientales; ArgentinaFil: Di Benedetto, Adalberto Hugo. Universidad Nacional de Mar del Plata. Facultad de Ciencias Agrarias; Argentina. Universidad de Buenos Aires. Facultad de Agronomia. Departamento de Producción Vegetal. Cátedra de Floricultura; Argentin

Being seen in your pyjamas : the relationship between fashion, class, gender and space

Over the last decade class has re-emerged as a significant concept within British sociology, with prominent academics calling for a more Bourdieuian approach which focuses on class distinctions in cultural practices and tastes. Within this discussion, several note the important role fashion plays as a means of class distinction, though few have fully explore just how the fashion-class relationship operates. Based on empirical research, carried out as part of qualitative study into fashion practices and fashion discourse, this article examines the fashion-class relationship, by considering its links to both gender and space. It argues that the way in which women judge visibility and public space differs with class status and that this in turn has significant implications for women's fashion choices, and more specifically, dressing up. Indeed, whilst middle class participants tend to view almost any space as public and one in which they are visible, for working class participants neighbourhood and local spaces are seen to constitute semi-private spaces, whose audiences' opinions and judgements do not matter. As a result, being dressed in your pyjamas is not deeply problematic for these working class women in the context of their everyday lives, while for their middle class counterparts being seen in your pyjamas is something which should be avoided, at all cost. Moreover, as the article demonstrate, the wearing of pyjamas is often considered by middle class respondents as indicative of working classness. And thus, being seen in your pyjamas is undesirable on two counts

Asymmetric Construction of Low-Latency and Length-Flexible Polar Codes

Polar codes are a class of capacity-achieving error correcting codes that have been selected for use in enhanced mobile broadband in the 3GPP 5th generation (5G) wireless standard. Most polar code research examines the original Arikan polar coding scheme, which is limited in block length to powers of two. This constraint presents a considerable obstacle since practical applications call for all code lengths to be readily available. Puncturing and shortening techniques allow for flexible polar codes, while multi-kernel polar codes produce native code lengths that are powers of two and/or three. In this work, we propose a new low complexity coding scheme called asymmetric polar coding that allows for any arbitrary block length. We present details on the generator matrix, frozen set design, and decoding schedule. Our scheme offers flexible polar code lengths with decoding complexity lower than equivalent state-of-the-art length-compatible approaches under successive cancellation decoding. Further, asymmetric decoding complexity is directly dependent on the codeword length rather than the nearest valid polar code length. We compare our scheme with other length matching techniques, and simulations are presented. Results show that asymmetric polar codes present similar error correction performance to the competing schemes, while dividing the number of SC decoding operations by up to a factor of 2 using the same codeword lengthComment: To appear in IEEE International Conference on Communications 2019 (Submitted October 12, 2018), 6 page