Robust leakage-based distributed precoder for cooperative multicell systems

Coordinated multipoint (CoMP) from long term evolution (LTE)-advanced is a promising technique to enhance the system spectral efficiency. Among the CoMP techniques, joint transmission has high communication requirements, because of the data sharing phase through the backhaul network, and coordinated scheduling and beamforming reduces the backhaul requirements, since no data sharing is necessary. Most of the available CoMP techniques consider perfect channel knowledge at the transmitters. Nevertheless for practical systems this is unrealistic. Therefore in this study the authors address this limitation by proposing a robust precoder for a multicell-based systems, where each base station (BS) has only access to an imperfect local channel estimate. They consider both the case with and without data sharing. The proposed precoder is designed in a distributed manner at each BS by maximising the signal-to-leakage-and-noise ratio of all jointly processed users. By considering the channel estimation error in the design of the precoder, they are able to reduce considerably the impact of these errors in the system's performance. The results show that the proposed scheme has improved performance especially for the high signal-to-noise ratio regime, where the impact of the channel estimation error may be more pronounced

Discovery of an ultramassive pulsating white dwarf

We announce the discovery of the most massive pulsating hydrogen-atmosphere (DA) white dwarf (WD) ever discovered, GD 518. Model atmosphere fits to the optical spectrum of this star show it is a 12,030 +/- 210 K WD with a log(g) = 9.08 +/- 0.06, which corresponds to a mass of 1.20 +/- 0.03 Msun. Stellar evolution models indicate that the progenitor of such a high-mass WD endured a stable carbon-burning phase, producing an oxygen-neon-core WD. The discovery of pulsations in GD 518 thus offers the first opportunity to probe the interior of a WD with a possible oxygen-neon core. Such a massive WD should also be significantly crystallized at this temperature. The star exhibits multi-periodic luminosity variations at timescales ranging from roughly 425-595 s and amplitudes up to 0.7%, consistent in period and amplitude with the observed variability of typical ZZ Ceti stars, which exhibit non-radial g-mode pulsations driven by a hydrogen partial ionization zone. Successfully unraveling both the total mass and core composition of GD 518 provides a unique opportunity to investigate intermediate-mass stellar evolution, and can possibly place an upper limit to the mass of a carbon-oxygen-core WD, which in turn constrains SNe Ia progenitor systems.Comment: 5 pages, 3 figures, Astrophysical Journal Letters, 771, L2 (2013

Study of cationic N-isopropylacrylamide-styrene copolymer latex particles using fluorescent probes

Monodisperse cationically charged core-shell poly[styrene/N-isopropylacrylamide] latexes, differing in their shell structure, were studied at temperatures around the lower critical solution temperature (LCST) of poly[N-isopropylacrylamide]. Near the LCST, a transition on the latex dimensions was observed by quasi-elastic light scattering measurements. The same transition could also be detected using the intensity ratio of the pyrene fluorescence vibronic bands, I1/I3, and the excimer to monomer fluorescence intensity ratio of 1,10-bis(1-pyrenyl)decane. The fluorescence spectra and decay curve measurements of 1,10-bis-(1-pyrenyl)decane provided a better understanding of both the hydrophilic-hydrophobic variation and the conformational changes occurring in the poly[N-isopropylacrylamide] shell of the latex particles upon temperature variation.J. M. G. Martinho is grateful for the support of this work from FCT. E. M. S. Castanheira acknowledges FCT for a grant (PRAXIS XXI/BPD/9968/96)

Sucrose in detoxification of coffee plants with glyphosate drift.

The weed control in coffee plants has great importance, as they compete for light, water and nutrients. The chemical control is the most used, emphasizing the glyphosate, however, when applied, drift can occur and consequently cause injuries to coffee. Many farmers use the sucrose application with the objective to reverse the damage caused by the herbicide drift, even without scientific basis to justify such action. The objective of this study was to evaluate the effect of the sucrose application on the detoxification of coffee plants in the implantation phase with glyphosate drift. The experiment was carried out in a greenhouse, using a randomized block design, arranged in a 3 x 3 factorial scheme with 2 additional treatments, using 3 sucrose doses (2, 4 and 8%) with 3 application times (1, 24 and 168 hours after intoxication with 10% of the commercial glyphosate dose) with an additional one in which the plants were not intoxicated and not treated with sucrose and another only with plants intoxicated by glyphosate. After 75 days performing the experiment, growth, physiological and anatomical characteristics were evaluated. The application of sucrose in the reversal of intoxication of growth variables (height, leaf area number of leaves, shoot dry weight and dry weight of the root system) was not efficient. The objective of this study was to evaluate the effect of the sucrose application on the detoxification of coffee plants in the implantation phase with glyphosate drift. For the physiological variables the application of 2% sucrose, one hour after glyphosate intoxication was the most efficient treatment

Interaction of a potential antitumoral benzothieno[3,2-b]pyrrole with lipid membranes and salmon sperm DNA

This work was funded by FCT and FEDER through CQ-UM and CFUM, project POCI/QUI/59407/2004 and post-Doc grant (SFRH/BPD/24548/2005) of A.S.A

Fluorescence studies on potential antitumoral heteroaryl and heteroannulated indoles in solution and in lipid membranes

Fluorescence properties of three potential antitumoral compounds, a 3-(dibenzothien-4-yl)indole 1, a phenylbenzothienoindole 2 and a 3-(dibenzofur-4-yl)indole 3, were studied in solution and in lipid aggregates of dipalmitoyl phosphatidylcholine (DPPC), dioleoyl phosphatidylethanolamine (DOPE) and egg yolk phosphatidylcholine (Egg-PC). The 3-(dibenzofur-4-yl)indole 3 exhibits the higher fluorescence quantum yields in all solvents studied (0.32 ≤ ΦF ≤ 0.51). All the compounds present a solvent sensitive emission, with significant red shifts in alcohols. The results point to an ICT character of the excited state, more pronounced for compound 1. Fluorescence (steady-state) anisotropy measurements of the compounds incorporated in lipid aggregates of DPPC, DOPE and Egg-PC indicate that the three compounds are deeply located in the lipid bilayer, feeling the difference between the rigid gel phase and fluid phases.Fundação para a Ciência e a Tecnologia (FCT) - Projecto POCI/QUI/59407/2004, bolsa doutoramento SFRH/BPD/24548/2005Fundo Europeu de Desenvolvimento Regional (FEDER

Fluorescence studies of new potential antitumoral indole derivatives in lipid membranes

This work was funded by FCT and FEDER through CFUM and CQ-UM, project POCI/QUI/59407/2004 and post-Doc grant (SFRH/BPD/24548/2005) of A.S.

Agronomic techniques for mitigating the effects of water restriction on coffee crops.

Water restriction significantly affects coffee (Coffea arabica L.) production. The study of a few agronomic techniques that optimizes water use can generate technologies for mitigating the effects of climatic variations on coffee crops. The aim in this study was to indicate agronomic techniques that mitigate the effects of water restriction on coffee crops. For this end, we analyzed the morphophysiological changes in coffee plants cultivated in a greenhouse with different types of fertilizers and soil conditioners and under two levels of irrigation. The evaluations were performed 130 days after planting, assessing the morphological and physiological characteristics of the plants. We also quantified soil moisture in the different treatments. The water restriction expressively hindered plant growth. The use of controlled release fertilizers and soil conditioners, especially coffee husk, is indicated for mitigating water restriction in coffee crops.Projeto 109 (Concafé)

New tetracyclic heteroaromatic compounds based on dehydroamino acids : photophysical and electrochemical studies of interaction with DNA

A benzothienoindole (BTIN) and a benzofuroindole (BFIN) were synthesized in high yields, as potential new target DNA compounds, using a metal-assisted intramolecular C-N cyclization, developed by us, of the methyl esters of N-(t-butoxycarbonyl)-b,b-bis(dibenzothien-4-yl or dibenzofuro-4-yl)dehydroalanines. The latter were obtained by a bis-Suzuki coupling of a b,b-dibromodehydroalanine with the corresponding heteroarylboronic acids. The absorption and fluorescence properties of the novel tetracyclic heteroaromatic compounds were studied in different solvents and in the presence of natural double-stranded (ds) salmon sperm DNA. The results in several solvents show that either BTIN or BFIN can be used as fluorescence solvent sensitive probes. Spectroscopic studies of the interaction of both compounds with dsDNA allowed to determine binding constant (Ki) values and binding site sizes (n). Fluorescence quenching experiments using iodide ion allowed the determination of the accessibilities to the quencher, showing that intercalation is the preferred mode of binding of these molecules to DNA. From the results obtained BTIN is the more intercalative compound and has a higher affinity to DNA. The interaction of this more promising compound with DNA was also studied electrochemically, by using differential pulse voltammetry (DPV) in connection with disposable pencil graphite electrode (PGE). These studies are based on the differences in the BTIN and adenine oxidation signals. After the interaction of BTIN with DNA, the oxidation signals of BTIN and adenine strongly decreased. The latter was attributed to the binding of the BTIN to DNA and the former points to a possible damage of the oxidizable groups of the compound after intercalation into DNA. Several concentrations of BTIN were tested and 50 μg/mL was found to be the optimum concentration in order to detect its interaction with DNA. In addition, the detection limit and the reproducibility were determined by using a disposable electrochemical transducer. The results of spectroscopic and electrochemical detection of BTIN interaction with DNA are in good agreement.Academy of Pharmacists and Turkish Pharmacists Association (TEB)Turkish Academy of Sciences - Young Scientist Award Program (KAE/TUBA-GEBIP/2001-2-8)FEDERFundação para a Ciência e a Tecnologia (FCT) - Projecto POCI/QUI/59407/2004. A.S.A. acknowledges a post-doc. grant SFRH/BPD/24548/2005, Bolsa SFRH/BPD/24548/2005.Scientific and Technical Research Council of Turkey (TUBITAK)

Precision asteroseismology of the pulsating white dwarf GD 1212 using a two-wheel-controlled Kepler spacecraft

We present a preliminary analysis of the cool pulsating white dwarf GD 1212, enabled by more than 11.5 days of space-based photometry obtained during an engineering test of the two-reaction-wheel-controlled Kepler spacecraft. We detect at least 19 independent pulsation modes, ranging from 828.2-1220.8 s, and at least 17 nonlinear combination frequencies of those independent pulsations. Our longest uninterrupted light curve, 9.0 days in length, evidences coherent difference frequencies at periods inaccessible from the ground, up to 14.5 hr, the longest-period signals ever detected in a pulsating white dwarf. These results mark some of the first science to come from a two-wheel-controlled Kepler spacecraft, proving the capability for unprecedented discoveries afforded by extending Kepler observations to the ecliptic.Comment: 8 pages, 4 figures, accepted for publication in The Astrophysical Journa