Publisher's Note: "Solution processed multilayer polymer light-emitting diodes based on different molecular weight host" (vol 109, 074516, 2011)

Solution processed multilayer polymer light-emitting diodes (PLEDs) based on different molecular weight host have been investigated. A PLED based on high molecular weight poly (vinyl carbazole) PVKH and low molecular weight poly (vinyl carbazole) PVKL, doped with iridium, tris(2-phenylpyidine) Ir(ppy)3 as a host-guest emitting layer (EML), shows a dramatic increase in device efficiency. When the PVKH was used as a hole transport electron blocking layer (HT-EBL), effective electron blocking was achieved, which leads to an increase exciton population in the phosphorescent zone. The use of low molecular weight PVKL as a host material in the top layer prevents barrier formation for hole transport from the poly(3,4-ethylenedioxy-thiophene) (PEDOT)–EBL to the EML. External quantum efficiency of 11%, current efficiencies of 38 cd/A, power efficiency of 13 lm/W and brightness of 7000 cd/m2, were obtained. The effect of the PVKH layer on the electrical and optical device characteristics was investigated. Simulation of the optical outcoupling using SETFOS 3.1 software is in agreed with the observed results and allowed us to predict the emissive dipole location and distribution in the EML layer. The effect of the PVKH on the exciton quenching by the electrodes was also investigated using time resolved fluorescence photon counting, which indicates weak exciton quenching by the PEDOT layer and the device enhancement predominantly achieved by exciton confinement in the emissive layer

Structural optimization of 3D masonry buildings

In the design of buildings, structural analysis is traditionally performed after the aesthetic design has been determined and has little influence on the overall form. In contrast, this paper presents an approach to guide the form towards a shape that is more structurally sound. Our work is centered on the study of how variations of the geometry might improve structural stability. We define a new measure of structural soundness for masonry buildings as well as cables, and derive its closed-form derivative with respect to the displacement of all the vertices describing the geometry. We start with a gradient descent tool which displaces each vertex along the gradient. We then introduce displacement operators, imposing constraints such as the preservation of orientation or thickness; or setting additional objectives such as volume minimization.Shell Oil CompanyNatural Sciences and Engineering Research Council of Canada (PGS Program)Samsung Scholarship Foundatio

Composition corporelle de poulets cou nu ou normalement emplumés: résultats dans un croisement de type chair

International audienc

Réponse de poulets normaux et nains (gène dw) à une privation d'aliment en phase de croissance

Les effets d’une privation d’aliment (eau ad libitum) pendant 72 heures à 8 semaines d’âge ont été examinés sur des poulets nains (mâles dwdw, femelles dw) et de taille normale (mâles Dw+dw, femelles Dw+) de même origine : femelles en cages individuelles, oiseaux des deux sexes au sol. Dans ce dernier cas, un lot non soumis au jeûne servait de témoin pour la reprise de poids après la privation d’aliment. Sur un autre échantillon de femelles, à partir de 11 semaines, la composition corporelle était comparée entre génotypes avec ou sans jeûne et une semaine après. Dans l’ensemble, les effets du jeûne sur les poulets nains et sur ceux de taille normale diffèrent peu. Les « nains » perdent légèrement moins de poids en % pendant le jeûne que les normaux, mais au sol seulement. Les différences entre génotypes concernant la température corporelle, le glucose ou l’acide urique plasmatique ne sont pas accusées par le jeûne. La reprise de poids relative durant les deux semaines consécutives est au total inférieure pour les animaux nains ; elle est décalée dans le temps pour ce génotype et un peu supérieure la seconde semaine au sol. La première semaine en cages, l’indice de consommation n’est pas meilleur pour les poulettes normales que pour les naines ; la remontée du pourcentage de lipides abdominaux après le jeûne à 11 semaines est plus précoce pour ce dernier génotype. Une augmentation de l’hématocrite des femelles dw pendant et après la privation d’aliment solide suggère une modification du bilan hydrique.The effects of starvation (water ad libitum) for 72 hours at 8 weeks of age have been studied in dwarf chicks (dwdw males and dw females) and normal-sized chicks of the same origin (Dw+dw males, Dw+ females). Only females were put into individual cages ; both sexes were kept in floor pens. In the latter case, body weight gain after the starvation period was compared to that of a control group without starvation. In another sample of females, the body composition of the two genotypes was compared, with or without starvation, at 11 weeks of age and 1 week later. The effects of starvation were not very different in dwarf and normal birds. In floor pens only, relative body weight loss during starvation was slightly less in dwarfs than in normals. Genotypic differences in body temperature, plasma glucose and uric acid were not significantly altered by starvation. The recovery of relative body weight during the 11 days after starvation was less, on the whole, for dwarf birds ; they recovered body weight later and their recovery rate was higher during the second week in floor pens. During the first week after starvation in cages, the food efficiency of normal pullets was not better than that of the dwarfs ; the percentage of abdominal fat after the end of starvation at 11 weeks increased earlier in dw birds. An increase in the hematocrit of dw females during and after starvation suggested a modification in the water balance during that time

Towards More Effective Techniques for Automatic Query Expansion

Techniques for automatic query expansion from top retrieved documents have recently shown promise for improving retrieval effectiveness on large collections but there is still a lack of systematic evaluation and comparative studies. In this paper we focus on term-scoring methods based on the differences between the distribution of terms in (pseudo-)relevant documents and the distribution of terms in all documents, seen as a complement or an alternative to more conventional techniques. We show that when such distributional methods are used to select expansion terms within Rocchio's classical reweighting scheme, the overall performance is not likely to improve. However, we also show that when the same distributional methods are used to both select and weight expansion terms the retrieval effectiveness may considerably improve. We then argue, based on their variation in performance on individual queries, that the set of ranked terms suggested by individual distributional methods can be combined to further improve mean performance, by analogy with ensembling classifiers, and present experimental evidence supporting this view. Taken together, our experiments show that with automatic query expansion it is possible to achieve performance gains as high as 21.34% over non-expanded query (for non-interpolated average precision). We also discuss the effect that the main parameters involved in automatic query expansion, such as query difficulty, number of selected documents, and number of selected terms, have on retrieval effectiveness

Insight into the Properties of Heteroleptic Metal Dithiolenes: Multistimuli Responsive Luminescence, Chromism, and Nonlinear Optics

A comprehensive investigation of the functional properties of heteroleptic donor-M-acceptor dithiolene complexes Bu4N[MII(L1)(L2)] is presented (M = Pd, Pt). The acceptor L1 consists of the chiral (R)-(+)α-methylbenzyldithiooxamidate ((R)-α-MBAdto), the donor L2 is 2-thioxo-1,3-dithiole-4,5-dithiolato (dmit) in 1 (Pd) and 2 (Pt), 1,2-dicarbomethoxyethylenedithiolate (ddmet) in 3 (Pd) and 4 (Pt), or [4′,5′:5,6][1,4]dithiino[2,3-b]quinoxaline-1′,3′-dithiolato (quinoxdt) in 5 (Pd) and 6 (Pt). L1 is capable of undergoing proton exchange and promoting crystal formation in noncentrosymmetric space groups. L2 has different molecular structures while it maintains similar electron-donating capabilities. Thanks to the synergy of the ligands, 1-6 behave as H+ and Ag+ switchable linear chromophores. Moreover, the compounds exhibit a H+-switchable second-order NLO response in solution, which is maintained in the bulk for 1, 3, and 4 when they are embedded into a PMMA poled matrix. 5 and 6 show unique anti-Kasha H+ and Ag+ tunable colored emission originating from the quinoxdt ligand. A correlation between the electronic structure and properties is shown through density functional theory (DFT) and time-dependent DFT calculations