402 research outputs found

    The Catalytic Vapor Phase Alkylation of Phenol by Alcohols

    Get PDF
    The object of this research is to study the reactions between phenol and various alcohols, using an activated alumina catalyst, at a temperature of 325 degrees Celsius. The alcohols, which are studied, are methyl, ethyl, and benzyl alcohol, respectively

    Controlling induced coherence for quantum imaging

    Full text link
    Induced coherence in parametric down-conversion between two coherently pumped nonlinear crystals that share a common idler mode can be used as an imaging technique. Based on the interference between the two signal modes of the crystals, an image can be reconstructed. By obtaining an expression for the interference pattern that is valid in both the low- and the high-gain regimes of parametric down-conversion, we show how the coherence of the light emitted by the two crystals can be controlled. With our comprehensive analysis we provide deeper insight into recent discussions about the application of induced coherence to imaging in different regimes. Moreover, we propose a scheme for optimizing the visibility of the interference pattern so that it directly corresponds to the degree of coherence of the light generated in the two crystals. We find that this scheme leads in the high-gain regime to a visibility arbitrarily close to unity.Comment: 9 pages, 4 figure

    Comparative Advantage, Learning, and Sectoral Wage Determination

    Get PDF
    We develop a model in which a worker's skills determine the worker's current wage and sector. Both the market and the worker are initially uncertain about some of the worker's skills. Endogenous wage changes and sector mobility occur as labor-market participants learn about these unobserved skills. We show how the model can be estimated using non-linear instrumental-variables techniques. We then apply our methodology to study the wages and allocation of workers across occupations and across industries. For both occupations and industries, we find that high-wage sectors employ high-skill workers and offer high returns to workers' skills. Estimates of these sectoral wage differences that do not account for sector-specific returns are therefore misleading. We also suggest further applications of our theory and methodology.

    Comparative Advantage, Learning, and Sectoral Wage Determination

    Get PDF
    We develop a model in which a worker's skills determine the worker's current wage and sector. Both the market and the worker are initially uncertain about some of the worker's skills. Endogenous wage changes and sector mobility occur as labor-market participants learn about these unobserved skills. We show how the model can be estimated using non-linear instrumental-variables techniques. We then apply our methodology to study the wages and allocation of workers across occupations and across industries. For both occupations and industries, we find that high-wage sectors employ high-skill workers and offer high returns to workers' skills. Estimates of these sectoral wage differences that do not account for sector-specific returns are therefore misleading. We also suggest further applications of our theory and methodology. Dans cet article, nous cherchons à développer un modèle par lequel le salaire d'un travailleur est fonction de ses qualifications. Le marché ainsi que le travailleur sont au préalable dans l'incertitude quant à certaines de ces qualifications. L'endogénéité à la fois des changements de salaire et des décisions de changements du secteur d'affiliation résulte du processus d'apprentissage relié aux qualifications du travailleur. Nous montrons ensuite comment le modèle peut être estimé par les méthodes des variables instrumentales non-linéaires. Nous appliquons notre méthodologie à l'étude des salaires et de l'allocation des travailleurs aux différentes occupations et industries. Nous trouvons que les secteurs à salaires élevés emploient des travailleurs ayant davantage de qualifications et que ces secteurs rémunèrent ces qualifications à un taux supérieur relativement aux secteurs à faibles salaires. Les estimés des rendements associés aux qualifications qui ne tiennent pas compte du fait que les rendements diffèrent d'un secteur à un autre sont par conséquent erronés. Nous proposons enfin d'autres applications possibles de notre méthodologie.comparative advantage, learning, non-linear instrumental variables, avantages comparés, apprentissage, variables instrumentales

    Engineering the Frequency Spectrum of Bright Squeezed Vacuum via Group Velocity Dispersion in an SU(1,1) Interferometer

    Full text link
    Bright squeezed vacuum, a promising tool for quantum information, can be generated by high-gain parametric down-conversion. However, its frequency and angular spectra are typically quite broad, which is undesirable for applications requiring single-mode radiation. We tailor the frequency spectrum of high-gain parametric down-conversion using an SU(1,1) interferometer consisting of two nonlinear crystals with a dispersive medium separating them. The dispersive medium allows us to select a narrow band of the frequency spectrum to be exponentially amplified by high-gain parametric amplification. The frequency spectrum is thereby narrowed from (56.5 +- 0.1) to (1.22 +- 0.02) THz and, in doing so, the number of frequency modes is reduced from approximately 50 to 1.82 +- 0.02. Moreover, this method provides control and flexibility over the spectrum of the generated light through the timing of the pump.Comment: 6 pages, 5 figure

    Les Témoins de Jéhovah et le refus de certains traitements : problèmes de forme, de capacité et de constitutionnalité découlant du « Code civil du Québec »

    Get PDF
    Les auteurs examinent, à la lumière du droit québécois, la validité de la carte portée par les Témoins de Jéhovah, carte avisant les instances médicales qu’aucune transfusion de sang ne doit leur être administrée dans les cas où ils seraient autrement incapables d’exprimer leur refus. Cet examen vise tant le majeur que le mineur apte. Les auteurs se penchent également sur certains articles spécifiques du « Code civil du Québec » concernant l’âge requis pour consentir aux soins médicaux, afin de savoir s’ils respectent les principes enchâssés dans la « Charte canadienne des droits et libertés » ainsi que dans la « Charte des droits et libertés de la personne ».Abstract: The writers examine the validity under Quebec law, of cards carried by Jehovah’s Witnesses which instruct health-care providers that no blood transfusions or products be administered to them, should they be otherwise incapable of expressing their refusal of such treatment. The issue of validity is raised not only when the refusal is made by adults but also by mature minors. The writers also discuss whether certain restrictive provisions of the « Civil Code » concerning the age of consent to medical care respect principles enunciated in the « Canadian Charter of Rights and Freedoms » and in Quebec’s « Charter of Human Rights and Freedoms »

    Nouveau Code civil du Québec

    Get PDF
    Les auteurs proposent une analyse de la portée de l'article 1490 du Code civil du Québec, une disposition nouvelle traitant des droits et obligations des parties lorsque la gestion des affaires d'autrui a été entreprise inopportunément. La première partie du commentaire souligne la distinction entre les notions d'opportunité et d'utilité dans le cadre de la gestion d'affaires, tandis que la deuxième partie examine les conséquences juridiques d'une gestion inutile et celles d'une gestion inopportunément entreprise.Abstract: The writers seek to analyze article 1490 of the Civil Code of Québec, an innovative provision which deals with the rights and obligations of the parties when the management of the business of another has been inopportunely undertaken. The first part sets out the distinction between the notions of opportuneness and of usefulness as they relate to the management of the business of another, whereas the second part examines the legal consequences of a management which has not been useful for the principal or which was not opportune when it was undertaken

    Genome-wide profiling of chromosome interactions in Plasmodium falciparum characterizes nuclear architecture and reconfigurations associated with antigenic variation.

    Get PDF
    Spatial relationships within the eukaryotic nucleus are essential for proper nuclear function. In Plasmodium falciparum, the repositioning of chromosomes has been implicated in the regulation of the expression of genes responsible for antigenic variation, and the formation of a single, peri-nuclear nucleolus results in the clustering of rDNA. Nevertheless, the precise spatial relationships between chromosomes remain poorly understood, because, until recently, techniques with sufficient resolution have been lacking. Here we have used chromosome conformation capture and second-generation sequencing to study changes in chromosome folding and spatial positioning that occur during switches in var gene expression. We have generated maps of chromosomal spatial affinities within the P. falciparum nucleus at 25 Kb resolution, revealing a structured nucleolus, an absence of chromosome territories, and confirming previously identified clustering of heterochromatin foci. We show that switches in var gene expression do not appear to involve interaction with a distant enhancer, but do result in local changes at the active locus. These maps reveal the folding properties of malaria chromosomes, validate known physical associations, and characterize the global landscape of spatial interactions. Collectively, our data provide critical information for a better understanding of gene expression regulation and antigenic variation in malaria parasites

    Randomized controlled trial of physiotherapy for postpartum stress incontinence : 7-year follow-up

    Get PDF
    Objective To estimate the long-term effect of intensive, 6-week physiotherapy programs, with and without deep abdominal muscle (TrA) training, on persistent postpartum stress urinary incontinence (SUI). Methods The study was a single-blind randomized controlled trial. Fifty-seven postnatal women with clinically demonstrated persistent SUI 3 months after delivery participated in 8 weeks of either pelvic floor muscle training (PFMT) (28) or PFMT with deep abdominal muscle training (PFMT + TrA) (29). Seven years post-treatment, 35 (61.4%) participants agreed to the follow-up; they were asked to complete a 20-min pad test and three incontinence-specific questionnaires with an assessor blinded to each participant's group assignment. Results: Of the 35 (61.4%) who agreed to the follow-up: 26 (45.6%) took the 20-min pad test (12 PFMT and 14 PFMT + TrA) and 35 (61.4%) completed the questionnaires (18 PFMT and 17 PFMT + TrA). The baseline clinical characteristics of the follow-up and non-follow-up participants were not significantly different; nor did they differ between PFMT and PFMT + TrA participants enrolled in the follow-up study. At 7 years, the pad test scores for the PFMT group did not differ statistically from those of the PFMT + TrA group. When combining both treatment groups, a total of 14/26 (53%) follow-up participants were still continent according to the pad test. Conclusion The addition of deep abdominal training does not appear to further improve the outcome of PFM training in the long term. However, benefits of physiotherapy for postpartum SUI, although not as pronounced as immediately after the initial intervention, is still present 7 years post-treatment

    PIP3-dependent macropinocytosis is incompatible with chemotaxis

    Get PDF
    In eukaryotic chemotaxis, the mechanisms connecting external signals to the motile apparatus remain unclear. The role of the lipid phosphatidylinositol 3,4,5-trisphosphate (PIP3) has been particularly controversial. PIP3 has many cellular roles, notably in growth control and macropinocytosis as well as cell motility. Here we show that PIP3 is not only unnecessary for Dictyostelium discoideum to migrate toward folate, but actively inhibits chemotaxis. We find that macropinosomes, but not pseudopods, in growing cells are dependent on PIP3. PIP3 patches in these cells show no directional bias, and overall only PIP3-free pseudopods orient up-gradient. The pseudopod driver suppressor of cAR mutations (SCAR)/WASP and verprolin homologue (WAVE) is not recruited to the center of PIP3 patches, just the edges, where it causes macropinosome formation. Wild-type cells, unlike the widely used axenic mutants, show little macropinocytosis and few large PIP3 patches, but migrate more efficiently toward folate. Tellingly, folate chemotaxis in axenic cells is rescued by knocking out phosphatidylinositide 3-kinases (PI 3-kinases). Thus PIP3 promotes macropinocytosis and interferes with pseudopod orientation during chemotaxis of growing cells
    • …
    corecore