Influence of human impacts on Albeluvisol analysed by X-ray microfluorescence: relative evolution of the transforming front at the tongue scale

In this paper we studied the nature and hierarchy of the processes responsible for soil evolution as a function of land use (forest and culture). Albeluvisols were chosen as a pedological model for this study. Iron, manganese, calcium, potassium and trace elements were used as indicators of the soil processes. Their spatial distribution was mapped along tongues of Albeluvisols at a pluri-centimetric scale, using X-ray microfluorescence. In both land use, Fe distribution was shown to be closely related to the soil colour variation along the tongues. Nickel and Cu followed the same distribution. Zinc was almost functioning as Fe with the difference that this element was not lost from the transition zone identified between the bleached tongues and the ochre volumes representative of the illuvial horizon. Under forest, the Fe and Mn redox fronts were closely associated that allows mapping them on the same thin section. Manganese disappeared from the neighbourhood of the iron redox front under agriculture. This was interpreted as a slow down of the iron redox process due to pH increase while Mn redox process was not modified. In addition, under forest, Ca seems totally leached. Liming causes an increase of Ca concentrations in the whole soil profile. This Ca is in an exchangeable form principally located at the interface between white and ochre volumes. We concluded that by liming, Man induced drastic changes in the kinetic of redox process in Albeluvisols over 200 years showing at the same time the extreme rapidity of these processes.     

802．11n将取代802．11g

9月17日,博通公司的无线连接集团高级总监Rahul Patel先生接受了本刊记者关于802．11n相关问题的采访。在采访中,Rahul Patel首先向记者介绍了Wi—Fi技术的发展情况以及Wi—Fi联盟目前的工作进展。他介绍说：“做为互联网世界的必然衍生产物,在过去4、5年中,Wi—Fi逐渐地集成到基于尖端通信半导体的消费类电子产品当中,其作用也开始显现。     

Study of the dynamic formation of transmission gratings recorded in photopolymers and holographic polymer-dispersed liquid crystals

Local and nonlocal models for the diffusion of photopolymers are applied to the dynamic formation of transmission gratings recorded in photopolymers and holographic polymer-dispersed liquid crystals (H-PDLCs). We retrieve the main parameters of H-PDLCs (refractive-index modulation and diffusion coefficient) by combining a solution of the one-dimensional diffusion equation and the rigorous coupled-wave theory applied to transmission gratings. The rigorous coupled-wave theory method provides us with information on higher harmonics of the refractive profile (not only on the first harmonic as when the classical Kogelnik theory is applied). Measurements concerning the second harmonic validate the modeling.     

First order random forests: Learning relational classifiers with complex aggregates

In relational learning, predictions for an individual are based not only on its own properties but also on the properties of a set of related individuals. Relational classifiers differ with respect to how they handle these sets: some use properties of the set as a whole (using aggregation), some refer to properties of specific individuals of the set, however, most classifiers do not combine both. This imposes an undesirable bias on these learners. This article describes a learning approach that avoids this bias, using first order random forests. Essentially, an ensemble of decision trees is constructed in which tests are first order logic queries. These queries may contain aggregate functions, the argument of which may again be a first order logic query. The introduction of aggregate functions in first order logic, as well as upgrading the forest’s uniform feature sampling procedure to the space of first order logic, generates a number of complications. We address these and propose a solution for them. The resulting first order random forest induction algorithm has been implemented and integrated in the ACE-ilProlog system, and experimentally evaluated on a variety of datasets. The results indicate that first order random forests with complex aggregates are an efficient and effective approach towards learning relational classifiers that involve aggregates over complex selections. Editor: Rui Camacho     

Dielectrophoretic segregation of different human cell types on microscope slides

A new method for preparing cells for microscopic examination is presented in which cell mixtures are fractionated by dielectrophoretic forces and simultaneously collected into characteristic zones on slides. The method traps cells directly from the suspending medium onto the slide, reducing cell loss. Furthermore, it exploits differences in the dielectric properties of the cells, which sensitively reflect their morphology. Because different cell types are trapped in characteristic zones on the slide, the technique represents an advance over existing methods for slide preparation, such as centrifugation and smears where cells are randomly distributed. In particular, the new method should aid in the detection of rare and anomalous cell subpopulations that might otherwise go unnoticed against a high background of normal cells. As well as being suitable for traditional microscopic examination and automated slide scanning approaches, it is compatible with histochemical and immunochemical techniques, as well as emerging molecular and proteomic methods. This paper describes the rationale and design of this so-called electrosmear instrumentation and shows experimental results that verify the theory and applicability of the method with model cell lines and normal peripheral blood subpopulations.     

The immunodetected yeast purine—cytosine permease is not N-linked glycosylated,nor are glycosylation sequences required to have a functional permease

The purine-cytosine permease (PCP) of the yeast Saccharomyces cerevisiae was detected by immunological methods. Using antibodies directed against synthetic peptides, whose sequences were derived from the primary structure of the PCP, immunoprecipitation of [³⁵S]methionine-labelled PCP was achieved either from cellular extracts or from in vitro translation mixtures. Non-labelled PCP was also detected on Western blots of membrane proteins. Similar migration rates were observed for PCP originating both from immunoprecipitated cellular extracts and from in vitro translation mixtures. Hence, post-translational processing, if any, only slightly affects the size of the protein. Also no evidence was found for N-linked core-glycosylation: identical migration rates were observed when immunoprecipitated PCP molecules were extracted from cells labelled for 10 min with [³⁵S]methionine, pretreated or not with tunicamycin. On the other hand, the suppresion of the two potential N-linked glycosylation sequences in the DNA did not lead to inactivation of the transport activity, confirming that N-linked glycosylation is not required for the permease activity.     

Diet and sterol biohydrogenation in the rat: Occurrence of epicoprostanol

The fecal sterols from rats fed several types of semipurified or commercial diets were analyzed by a combination of thin layer and gas liquid chromatography. In rats fed semipurified diets with lard, sucrose, and casein, increasing proportions of lard (0, 8, 20, 65%) enhanced the fecal coprostanol/coprostanol + cholesterol ratio (from 0.50 to 0.85). This ratio was reduced by replacing lard with triolein or a mixture of calcium oleate and linoleate (1∶1) and did not change when trierucin was substituted. No coprostanol formation was observed in rats fed a diet with tripalmitin or tristearin. The addition of sodium hyodeoxycholate (0.5%) or cholestyramine (2%) to the basal diet was without effect on the coprostanol/coprostanol + cholesterol ratio in the feces. The addition of sodium taurocholate (0.2, 0.75, and 4%) strongly reduced coprostanol formation, while a chronic bile duct ligation led to an enhancement. Cholesterol feeding (0.05, 0.2, and 0.5% in the diet) slightly increased (from 51 to 66%) coprostanol formation. Trace amounts of epicoprostanol were generally found in the feces. However, in some cases a very high proportion (up to 60%) of this sterol was observed. Possible relationships between the presence of epicoprostanol and the nature of the diet are discussed.     

Workshop on hydrogen effect in InP and related compounds

One of the primary technological interests in hydrogen in semiconductors concerns the ease with which it is introduced during crystal growth and processing. Hydrogen can move during device operations and hence alter device characteristics. It is thus necessary to understand how hydrogen is introduced in semiconductors and to be able to detect its presence. Thus, in order to give potential answers to these problems, several topics were discussed. They covered all the hydrogenation effects through : device-related applications, hydrogen-surface interaction, acceptors and donor passivation, unintentional hydrogénation, proton implantation and related problems. Finally, unsolved issues are reviewed in a final talk.