Language identification of multilingual posts from Twitter: a case study

This paper describes a method for handling multi-class and multi-label classification problems based on the support vector machine formalism. This method has been applied to the language identification problem in Twitter. The system evaluation was performed mainly on a Twitter data set developed in the TweetLID workshop. This data set contains bilingual tweets written in the most commonly used Iberian languages (i.e., Spanish, Portuguese, Catalan, Basque, and Galician) as well as the English language. We address the following problems: (1) social media texts. We propose a suitable tokenization that processes the peculiarities of Twitter; (2) multilingual tweets. Since a tweet can belong to more than one language, we need to use a multi-class and multi-label classifier; (3) similar languages. We study the main confusions among similar languages; and (4) unbalanced classes. We propose threshold-based strategy to favor classes with less data. We have also studied the use of Wikipedia and the addition of new tweets in order to increase the training data set. Additionally, we have tested our system on Bergsma corpus, a collection of tweets in nine languages, focusing on confusable languages using the Cyrillic, Arabic, and Devanagari alphabets. To our knowledge, we obtained the best results published on the TweetLID data set and results that are in line with the best results published on Bergsma data set.     

Genetic potential for N2O emissions from the sediment of a free water surface constructed wetland

Removal of nitrogen is a key aspect in the functioning of constructed wetlands. However, incomplete denitrification may result in the net emission of the greenhouse gas nitrous oxide (N₂O) resulting in an undesired effect of a system supposed to provide an ecosystem service. In this work we evaluated the genetic potential for N₂O emissions in relation to the presence or absence of Phragmites and Typha in a free water surface constructed wetland (FWS-CW), since vegetation, through the increase in organic matter due to litter degradation, may significantly affect the denitrification capacity in planted areas. Quantitative real-time PCR analyses of genes in the denitrification pathway indicating capacity to produce or reduce N₂O were conducted at periods of different water discharge. Genetic potential for N₂O emissions was estimated from the relative abundances of all denitrification genes and nitrous oxide reductase encoding genes (nosZ). nosZ abundance was invariably lower than the other denitrifying genes (down to 100 fold), and differences increased significantly during periods of high nitrate loads in the CW suggesting a higher genetic potential for N₂O emissions. This situation coincided with lower nitrogen removal efficiencies in the treatment cell. The presence and the type of vegetation, mainly due to changes in the sediment carbon and nitrogen content, correlated negatively to the ratio between nitrate and nitrite reducers and positively to the ratio between nitrite and nitrous oxide reducers. These results suggest that the potential for nitrous oxide emissions is higher in vegetated sediments.     

Single-shot color digital holography based on the fractional Talbot effect

We present a method for recording on-axis color digital holograms in a single shot. Our system performs parallel phase-shifting interferometry by using the fractional Talbot effect for every chromatic channel simultaneously. A two-dimensional binary amplitude grating is used to generate Talbot periodic phase distributions in the reference beam. The interference patterns corresponding to the three chromatic channels are captured at once at different axial distances. In this scheme, one-shot recording and digital reconstruction allow for real-time measurement. Computer simulations and experimental results confirm the validity of our method.     

Understanding pore rearrangement during mild to hard transition in bilayered porous anodic alumina membranes

We present a systematic study about the influence of the main anodization parameters (i.e., anodization voltage ramp and hard anodization voltage) on the pore rearrangement in nanoporous anodic alumina during mild to hard anodization regime transition. To cover the ranges between mild and hard regimes, the anodization parameters were each set to three levels (i.e., 0.5, 1.0, and 2.0 V s(-1) for the anodization voltage ramp and 80, 110, and 140 V for the hard anodization voltage). To the best of our knowledge, this is the first rigorous study about this phenomenon, which is quantified indirectly by means of a nickel electrodeposition. It is found that pore rearrangement takes place in a relatively random manner. Large areas of pores remain blocked when the anodization regime changes from mild to hard and, under certain anodization conditions, a pore branching takes place based on the self-ordering mechanism at work during anodization. Furthermore, it is statistically demonstrated by means of a design of experiments strategy that the effect of the anodization voltage ramp on the pore rearrangement is practically negligible in contrast to the hard anodization voltage effect. It is expected that this study gives a better understanding of structural changes in nanoporous anodic alumina when anodization is switched from mild to hard regime. Furthermore, the resulting nanostructures could be used to develop a wide range of nanodevices (e.g., waveguides, 1D photonic crystals, Fabry-Pe?rot interferometers, hybrid mosaic arrays of nanowires).     

Review of the efficacy of green tea, isoflavones and aloe vera supplements based on randomised controlled trials

We assess the evidence for health benefits of three commonly consumed plant food supplements (PFS), green tea, isoflavone and aloe vera, based on published systematic reviews of randomised controlled trials (RCTs). Whilst the potential benefits of green tea have been reported in a wide range of health areas, it is only in the area of the metabolic syndrome that the number of RCTs is approaching sufficient to judge such efficacy. Isoflavone supplements are widely used, and RCTs indicate that they affect bone resorption at lower doses in postmenopausal women undergoing estrogen-related bone loss, but this is only translated to attenuation of bone loss at higher doses of isoflavones. A systematic review on RCTs concluded that the effects of isoflavones on hot flashes in postmenopausal women were highly variable and no conclusions could be drawn. Despite the popularity of aloe vera as a PFS, the evaluation of its efficacy as a coadjuvant therapy for certain metabolic or digestive pathologies remains scarce; it constitutes a typical example of a naturally occurring ingredient whose efficacy in topical applications presupposes its efficacy in systemic applications. Nevertheless, its possible toxic effects on oral consumption call for caution in its utility as a PFS. Since 2007, efficacy evaluation of PFS in Europe has been covered by European Union Nutrition and Health Claims legislation. The European Food Safety Authority has adopted an approach relying on RCTs, while medicinal effects are accepted based on traditional use. In general, there are insufficient RCTs for claims to be made, and conclusive results on PFS should be obtained in the future by conducting studies with more homogeneous populations, by using supplements with optimised and measured bioavailability, and by conducting larger RCTs.     

Stochastic convergence in the industrial sector of the Mexican states

We investigate the convergence process experienced by the industrial sector of the Mexican states covering the period 1960–1998. Our analysis indicates that misleading conclusions can be obtained if the presence of structural breaks is not taken into account when testing for the presence of convergence. Thus, after allowing for structural breaks evidence in favour of industrial labour productivity convergence is found using unit root tests for some Mexican states. However, empirical evidence suggests that states with the smallest industrial share diverge from below. Besides, states with the major industrial share diverge from above. A great majority of states are involved in clear convergence process.     

Endogenous cholecystokinin enhances postprandial gastroesophageal reflux in humans through extrasphincteric receptors

Administration of either ammonia or glycine to both rats and mice results in an increased synthesis in the liver and urinary excretion of orotic acid. The two most relevant observations obtained are that carbamoyl phosphate synthesized inside the mitochondria is involved in the increased synthesis of orotic acid and that this latter process is almost completely abolished by cycloheximide and actinomycin D, inhibitors of protein and RNA synthesis. Orotic acid synthesis could be controlled by an induction-suppression mechanism. Inhibition of synthesis of excess orotic acid brought about by N-(phosphonacetyl)-L-aspartic acid but not by acivicin, suggests that glutamine-dependent cytosolic synthesis of carbamoyl phosphate, is not involved. Administration of ornithine together with glycine completely suppressed the synthesis of orotic acid, but promoted a twofold increase of urea excretion. The concentration of ornithine rather than that of carbamoyl phosphate or the activity of the enzymes involved, may represent a limiting factor controlling both the flux of ammonia in the urea cycle and the availability of mitochondrial carbamoyl phosphate for orotic acid synthesis. Two enzymes have been found to be induced by glycine: ornithine decarboxylase and aspartate transcarbamoylase (aspartate carbamoyltransferase). Both enzymes may contribute to the increase in orotic acid synthesis, aspartate transcarbamoylase more directly and ornithine decarboxylase by lowering the ornithine concentration. Ornithine decarboxylase activity was completely suppressed but that of aspartate transcarbamoylase was further increased by cycloheximide treatment. Inhibition of orotic acid biosynthesis by cycloheximide appears to be the result of a decreased availability in the cytosol of carbamoyl phosphate synthesized inside the mitochondria.     

文东油田解除近井地带盐堵技术

本文评述了近几年在文东油田近开地带解除盐堵的研究、应用成果,主要是化学解堵剂的筛选、评价及包括向地层挤化学药剂解堵、连续接水微渗透淡化解堵、过桥系结合化学药剂冲盐解堵等一套解堵技术。