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How do parties protect themselves from electoral manipulation? To answer this question, we study the drivers of polling station party representatives’ presence and their impact on electoral outcomes in an environment where electoral irregularities are common. Using election data from the Mexican Chamber of Deputies, we find a robust positive correlation between the presence of party representatives and that party’s vote share. The evidence suggests that this correlation can be attributed to party representatives influencing the electoral results. We also formulate a game theoretic model of the levels of representation chosen by parties in a given precinct and structurally estimate its parameters. We find that parties send their representatives where they expect their opponents to send their own. The finding suggests representatives play a primarily protective role, even when they are often involved in irregularities themselves.
Human milk oligosaccharides (HMO) are involved in many biological functions influencing infant health. Although HMO act locally at the intestine, recent evidence has demonstrated that HMO are partially incorporated into the systemic circulation of breast-fed infants. In the last few years, a large amount of research has been conducted using preclinical models to uncover new biological functions of HMO. The aim of this study was to evaluate the absorption and urine excretion of HMO in rats. We administered a single oral dose of the following HMO: 2'-fucosyllactose (2'-FL), 6'-sialyllactose and lacto-N-neotetraose at different concentrations to adult rats. The time course of absorption of HMO into the bloodstream and their appearance in urine was studied. Our results showed that rats, similar to human infants, are able to effectively absorb a portion of HMO from the intestine into plasma and to excrete them in urine. On the basis of this, we also conducted a specific kinetic absorption study with 2'-FL, the most predominant HMO in human milk, in 9–11-d-old rat pups. Our results confirmed that a significant amount of 2'-FL was absorbed into the systemic circulation and subsequently excreted in urine during lactation in rats in a dose-depended manner. We also found basal levels of these HMO in plasma and urine of adult rats as well as rat pups as a natural result of nursing. Our data suggest that the rat may be a useful preclinical model that provides new insights into the metabolism and functions of HMO.
The effect of conditioning on an additional covariate on confounding bias depends, in part, on covariates that are unobserved. We characterize the conditions under which the interaction between a covariate that is available for conditioning and one that is not can affect bias. When the confounding effects of two covariates, one of which is observed, are countervailing (in opposite directions), conditioning on the observed covariate can increase bias. We demonstrate this possibility analytically, and then show that these conditions are not rare in actual data. We also consider whether balance tests or sensitivity analysis can be used to justify the inclusion of an additional covariate. Our results indicate that neither provide protection against overadjustment.
The possibility to divide GRBs in different subclasses allow to understand better the
physics underlying their emission mechanisms and progenitors. The induced gravitational
collapse scenario proposes a binary progenitor to explain the time-sequence in GRBs-SNe.
We show the existence of a common behavior of the late decay of the X-ray afterglow
emission of this subclass of GRBs, pointing to a common physical mechanism of their late
emission, consistent with the IGC picture.
ZnO is a promising material for use in solar cell applications which require antireflective coatings and transparent conducting materials in front contacts. Its resistivity can be reduced by appropriate doping with different group III elements, which act as donors, without sacrificing optical transmission. Besides, it constitutes a non-toxic and cheap alternative to ITO (In2O3:SnO2), which is nowadays commonly used as transparent conducting oxide (TCO) in optoelectronic devices. Al(III) is one of the cheapest elements on nature, and has been therefore one of the first candidates to be used as a dopant. However recent studies demonstrate that for similar amounts of dopant the use of Ga largely improves both the optical and electrical properties of the films. The interface between Si (used as substrate) and the corresponding TCO is a critical part of Si-based solar cells, since the conversion efficiency may be profoundly altered by the presence of recombination centers formed at the interface. In this work we present a comparison of Si/ZnO, Si/ZnO:Ga and Si/ZnO:Al interfaces (with [dopant]/[Zn] = 2%) by using HRTEM and associated spectroscopies. Resistivity values of the films are: ρ(ZnO) = 4.4 × 10-2 Ω × cm; ρ(Ga:ZnO) = 6.3 × 10-4 Ω × cm; ρ(Al:ZnO) = 2.9 × 10-3 Ω × cm. and the films optical transmitance is larger than 80% along the visible spectrum.
Polypyrrole has been electrocleposited in the interior of the pores that form the Porous Silicon structure, and a very significant increase of the electrical conductivity of the samples has been observed. The degree of filling by the polymer has been found to be highly dependent on the electropolymerization conditions. Micro-Raman Spectroscopy experiments have allowed us to measure the amount of polymer as a function to the distance from the outer PS surface.
We have measured the Raman spectrum of porous silicon layers for different light polarizations. For the polarizations where the first-order Raman peak is forbidden in bulk silicon, porous silicon shows a band. This band is almost as intense as the one in the allowed polarizations but its lineshape is very different. The ‘forbidden’ band is usually wider and shifted to lower energies with respect to the allowed band. Both bands are analyzed in terms of sample characteristics, layer depth, and excitation wavelength.
We have measured micro-photoluminescence (PL) and micro-Raman spectra on the cross section of porous silicon multilayers to sample different layer depths. We find noticeable differences in the spectra of layers with different porosity, as expected from the quantum confinement of electrons and phonons in silicon nanocrystals with different average sizes. The PL emission band gets stronger, blue shifts, and narrows at the high porosity layers. The average size can be estimated from the shift. The Raman phonon band at 520 cm−1 weakens and broadens asymmetrically towards the low energy side. The line shape can be related quantitatively with the average size by the phonon confinement model. To get a good agreement with the model we add a band at around 480 cm−1, which has been attributed to amorphous silicon. We also have to leave as free parameters the bulk silicon phonon frequency and its line width, which depend on temperature and stress. We reduced laser power to eliminate heating effects. Then we use the change of frequency with depth to monitor the stress. At the interface with the substrate we find a compressive stress in excess of 10 kbar, which agrees with the reported lattice mismatch. Finally, average sizes are larger than those estimated from PL.
Sediment and plant-associated macroinvertebrates were sampled in six shallow water bodies along the central part of the coast
of Mediterranean Spain. The size of ponds, salinity and hydroperiod were highly variable. Seventy-one taxa were recorded, some
of them were endemic or uncommon species, evidencing the important contribution of these ponds to biodiversity. Crustaceans
and gastropods of biogeographical interest were found in the most primeval site. Correspondence analysis showed that macroinvertebrate
assemblages responded to environmental variables such as salinity, temporality and eutrophication. The brackish
water fauna was dominated by crustaceans, while oligochaeta and insect larvae were abundant in freshwater conditions.
Oligochaetes were abundant at localities with high trophic level, whereas localities with semi-permanent waters were dominated
by chironomids. The density of macroinvertebrates was clearly related with trophic state but we did not find significant relationships
between density and salinity or water permanence. For plant associated samples our results showed negative relationships
between species richness and temporality or salinity, contrary to sediment samples, where the Oligochaeta/Chironomidae
ratio in sediments and the percentage of sensitive taxa (Ephemeroptera, Odonata, Trichoptera) were useful indices, and were
dependent on pond typology. This study emphasizes the broad ecological variety of ponds found in these wetlands and their
importance for biodiversity. Some ponds act as permanent biodiversity reservoirs in fluctuant marshes with seasonal dryness,
calling for more attention on their ecological relevance for management strategies.
Fluorine doped tin oxide (FTO) thin films have been prepared by spray
pyrolysis technique with no further annealing. Films with 2.5% of fluorine grown at 400 °C present a single phase and exhibit a tetragonal structure with lattice parameters a = 4.687 Å and c = 3.160 Å. Scanning electron micrographs showed homogeneous surfaces with average grain size around 190 nm.
The films are transparent in the visible zone and exhibit a high reflectance in the near infrared region. The best electrical resistivity was 6.3 × 10-4 Ω cm for FTO with 2.5% of fluorine. The ratio of transmittance in the visible to the sheet resistance are in the 0.57 × 10-2–1.96 × 10-2 Ω-1 range.
DE CVn is a relatively unstudied eclipsing binary where one of the components is an M dwarf and the other is a white dwarf. Its brightness makes it an ideal system for a detailed study in the context of common-envelope evolution of a detached white dwarf – red dwarf binary with a relatively short orbital period (∼8.7 hours). We present a detailed study of the basic parameters (e.g. orbital period, components' masses and spectral types) for this system from photometric and spectroscopic studies. The eclipses observed during several photometric observing runs were used to derive the ephemeris. We have used spectroscopic data to derive the radial velocity variations of the emission lines and these are used to determine the components' masses and the orbital separation. The secondary component in DE CVn is an M3 main-sequence star and the primary star, which only contributes to the blue continuum, is a cool white dwarf with a temperature of ∼8000 K. From the photometry and spectroscopy together, we have set a limit on the binary inclination. This system is a post-common-envelope system where the progenitor of the present day white dwarf was a low-mass star (M≤2M⊙). The time before DE CVn becomes a semi-detached system is longer than the Hubble time.
Through a pooled cross-section time-series analysis of the determinants of wage inequality in sixteen OECD countries from 1973 to 1995, we explore how political-institutional variables affect the upper and lower halves of the wage distribution. Our regression results indicate that unionization, centralization of wage bargaining and public-sector employment primarily affect the distribution of wages by boosting the relative position of unskilled workers, while the egalitarian effects of Left government operate at the upper end of the wage hierarchy, holding back the wage growth of well-paid workers. Further analysis shows that the differential effects of government partisanship are contingent on wage-bargaining centralization: in decentralized bargaining systems, Left government is associated with compression of both halves of the wage distribution.
Nilaparvata lugens (Stål) biotype 1, 2 and 3 populations maintained as stock cultures for several years showed distinct morphological segregation based on multiple discriminant analysis using Wilk's Lambda method. Morphological characters of the rostrum, legs and antennae of both brachypterous and macropterous males and females provided a significant degree of certainty in classifying the three biotypes. The predicted biotype composition of the brown planthopper populations formed separate clusters.
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