10,892 research outputs found

    Signal amplification and control in optical cavities with off-axis feedback

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    We consider a large class of optical cavities and gain media with an off-axis external feedback which introduces a two-point nonlocality. This nonlocality moves the lasing threshold and opens large windows of control parameters where weak light spots can be strongly amplified while the background radiation remains very low. Furthermore, transverse phase and group velocities of a signal can be independently tuned and this enables to steer it non mechanically, to control its spatial chirping and to split it into two counter-propagating ones.Comment: 4 pages, 4 picture

    Shock effects in plagioclase feldspar from the Mistastin Lake impact structure, Canada

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    Shock metamorphism, caused by hypervelocity impact, is a poorly understood process in feldspar due to the complexity of the crystal structure, the relative ease of weathering, and chemical variations, making optical studies of shocked feldspars challenging. Understanding shock metamorphism in feldspars, and plagioclase in particular, is vital for understanding the history of Earth's moon, Mars, and many other planetary bodies. We present here a comprehensive study of shock effects in andesine and labradorite from the Mistastin Lake impact structure, Labrador, Canada. Samples from a range of different settings were studied, from in situ central uplift materials to clasts from various breccias and impact melt rocks. Evidence of shock metamorphism includes undulose extinction, offset twins, kinked twins, alternate twin deformation, and partial to complete transformation to diaplectic plagioclase glass. In some cases, isotropization of alternating twin lamellae was observed. Planar deformation features (PDFs) are notably absent in the plagioclase, even when present in neighboring quartz grains. It is notable that various microlites, twin planes, and compositionally different lamellae could easily be mistaken for PDFs and so care must be taken. A pseudomorphous zeolite phase (levyne-Ca) was identified as a replacement mineral of diaplectic feldspar glass in some samples, which could, in some instances, also be potentially mistaken for PDFs. We suggest that the lack of PDFs in plagioclase could be due to a combination of structural controls relating to the crystal structure of different feldspars and/or the presence of existing planes of weakness in the form of twin and cleavage planes

    Toward quantification of strain-related mosaicity in shocked lunar and terrestrial plagioclase by in situ micro-X-ray diffraction

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    Studies of shock metamorphism of feldspar typically rely on qualitative petrographic observations, which, while providing invaluable information, can be difficult to interpret. Shocked feldspars, therefore, are now being studied in greater detail by various groups using a variety of modern techniques. We apply in situ micro-X-ray diffraction (μXRD) to shocked lunar and terrestrial plagioclase feldspar to contribute to the development of a quantitative scale of shock deformation for the feldspar group. Andesine and labradorite from the Mistastin Lake impact structure, Labrador, Canada, and anorthite from Earth's Moon, returned during the Apollo program, were examined using optical petrography and assigned to subgroups of the optical shock level classification system of Stöffler (1971). Two-dimensional μXRD patterns from the same samples revealed increased peak broadening in the chi dimension (χ), due to strain-related mosaicity, with increased optical signs of deformation. Measurement of the full width at half maximum along χ (FWHMχ) of these peaks provides a quantitative way to measure strain-related mosaicity in plagioclase feldspar as a proxy for shock level

    Direct introduction of cloned DNA into the sea urchin zygote nucleus, and fate of injected DNA

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    A method is described for microinjection of cloned DNA into the zygote nucleus of Lytechinus variegatus. Eggs of this species are unusually transparent, facilitating visual monitoring of the injection process. The initial fate of injected DNA fragments appears similar to that observed earlier for exogenous DNA injected into unfertilized egg cytoplasm. Thus after end-to-end ligation, it is replicated after a lag of several hours to an extent indicating that it probably participates in most of the later rounds of DNA synthesis undergone by the host cell genomes during cleavage. The different consequences of nuclear versus cytoplasmic injection are evident at advanced larval stages. Larvae descendant from eggs in which exogenous DNA was injected into the nuclei are four times more likely (32% versus 8%) to retain this DNA in cell lineages that replicate very extensively during larval growth, i.e. the lineages contributing to the imaginal rudiment, and thus to display greatly enhanced contents of the exogenous DNA. Similarly, 36% of postmetamorphic juveniles from a nuclear injection sample retained the exogenous DNA sequences, compared to 12% of juveniles from a cytoplasmic injection sample. However, the number of copies of the exogenous DNA sequences retained per average genome in postmetamorphic juveniles was usually less than 0.1 (range 0.05-50), and genome blot hybridizations indicate that these sequences are organized as integrated, randomly oriented, end-to-end molecular concatenates. It follows that only a small fraction of the cells of the average juvenile usually retains the exogenous sequences. Thus, even when introduced by nuclear microinjection, the stable incorporation of exogenous DNA in the embryo occurs in a mosaic fashion, although in many recipients the DNA enters a wider range of cell lineages than is typical after cytoplasmic injection. Nuclear injection would probably be the route of choice for studies of exogenous DNA function in the postembryonic larval rudiment

    Use of pharmacological treatments by a sample of Italian patients affected by alcohol use disorders

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    Title: USE OF PHARMACOLOGICAL TREATMENTS BY A SAMPLE OF ITALIAN PATIENTS AFFECTED BY ALCOHOL USE DISORDERS Author name(s): R. Agabio; E.M. Diana; D. Grazzini; R. Pirastu; G.L. Gessa Institution: Department of Biochemical Sciences, Section of Neuroscience, Preclinical and Clinical Pharmacology, University of Cagliari, Italy Text Background: It has often been reported that the majority of patients affected by Alcohol Use Disorders (AUDs) do not receive any pharmacological treatment. This study was aimed at investigating the use of the medications available in Italy (disulfiram, naltrexone, acamprosate, and γ-hydroxybutyric acid) by a sample of outpatients affected by AUDs. Methods: Four trained psychologists interviewed outpatients affected by AUDs in an area of Sardinia, Italy, of approximately 550.000 adult inhabitants. Results: A total sample of 208 outpatients affected by AUDs was interviewed (~1/3 of total outpatients affected by AUDs of that area). Their main features were: 166 males (79.5%); mean age=48.6±0.6 year; duration of AUDs=15.8±0.7 years; number of drinks per drinking days=19.4±1.3; number of criteria of DSM-IV-Tr=5.8±0.1. Before the admission into specific services, 13 patients (6.2%) had already received medication for AUDs; 7 patients (3.4%) had received disulfiram and 6 patients (2.9%) γ-hydroxybutyric acid. Over the same period, 22 patients (10.6%) had already attended self-help groups and 4 patients (1.9%) had received thiamine (Vitamine B1). After the admission into specific medical settings for the treatment of AUDs, 113 patients (54.3%) received medication for AUDs: 58 patients (27.9%) received disulfiram, 65 patients (31.2%) γ-hydroxybutyric acid, 2 patients (1.0%) naltrexone, and 6 patients (2.9%) acamprosate. In the same period, 54 patients (26.0%) frequented self-help associations, and 21 patients (10.1%) received thiamine. Conclusions: The results of this study confirm that the number of patients who receive a treatment for AUDs continues to be surprisingly low. Despite the long duration and the high level of severity of the AUDs, the majority of patients affected by AUDs did not receive any treatment before their admission in specific medical settings for the treatment of AUDs (10% of patients frequented self-help groups, 6% received a medication for AUDs, and 2% thiamine). After the admission into specific medical settings, the number of patients who received a treatment increased: 26% frequented self-help associations, 54% received a specific medication, and 10% received thiamine. However, approximately half of the patients did not receive any pharmacological treatment even if they frequented medical settings for the treatment of AUDs. Additional work is needed to understand the reasons of such a scarce use of treatments. Acknowledgements: This study was supported by a grant from Regione Autonoma della Sardegna

    Calderón y el refranero

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    En la contribución se analiza la presencia del refranero en las comedias de Calderón de la Barca. Lo que llama inmediatamente la atención es el hecho de que muchas de las piezas de don Pedro llevan como título un refrán; es evidente, además, que partiendo del título el dramaturgo elabora la intriga, usando repetidas veces el refrán-título en los versos. La finalidad del estudio no estriba sólo en la localización de las paremias en entramado léxico, sino también en analizar las modalidades de inserción y en averiguar si el proverbio se cita como tal o si se reelabora dentro del texto. This paper aims at analysing the corpus of proverbs in Calderónde la Barca’s plays. As a matter of fact, many of don Pedro’s plays are entitled according to one of the corpus proverbs. Furthermore, the plot is always elaborated starting from the title and the title proverb is continuosly inserted in the text. This essay aims not only at finding proverbial quotations into the lexical structure, but especially at discovering how they have been inserted as well as the level of awareness in every quotation

    Review of Dan Zuberi, \u3cem\u3eDifferences That Matter: Social Policy and the Working Poor in the United States and Canada\u3c/em\u3e

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    My chief regret is that Mettler\u27s messages may fall between two chairs. In striving to reach a wider readership through simple and schematic language, her book does not give serious students of public policy enough empirical and theoretical meat to chew on. (One might call the book a tasting menu. ) At the same time, to Mettler\u27s credit, the book is just not sufficiently folksy and anecdotal to make it a likely candidate for The New York Times\u27s best-seller list. But read it anyway. You will still learn a lot
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