102,729 research outputs found

    Holographic analysis of thin films

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    Technique for monitoring deposition of films on surfaces, in place on a real-time basis, reads both the thickness and the uniformity of the deposited film. Holograms are produced from both reflected and transmitted light on one plate

    Analysis of radar images of the active volcanic zone at Krafla, Iceland: The effects of look azimuth biasing

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    The geomorphic expression of Mid-Ocean-Ridge (MOR) volcanism in a subaerial setting occurs uniquely on Earth in Iceland, and the most recent MOR eruptive activity has been concentrated in the Northeastern Volcanic Zone in an area known as Krafla. Within the Krafla region are many of the key morphologic elements of MOR-related basaltic volcanism, as well as volcanic explosion craters, subglacial lava shields, tectonic fissure swarms known as gjar, and basaltic-andesite flows with well developed ogives (pressure-ridges). The objective was to quantify the degree to which the basic volcanic and structural features can be mapped from directional SAR imagery as a function of the look azimuth. To accomplish this, the current expression of volcanic and tectonic constructs was independently mapped within the Krafla region on the E, W, and N-looking SAR images, as well as from SPOT Panchromatic imagery acquired in 1987. The initial observations of the E, W, and N images indicates that fresh a'a lava surfaces are extremely radar bright (rough at 3 cm to meter scales) independent of look direction; this suggests that these flows do not have strong flow direction related structures at meter and cm scales, which is consistent with typical Icelandic a'a lava surfaces in general. The basic impression from a preliminary analysis of the effects of look azimuth biasing on interpretation of the geology of an active MOR volcanic zone is that up to 30 percent of the diagnostic features can be missed at any given look direction, but that having two orthogonal look direction images is probably sufficient to prevent gross misinterpretation

    Notes on a new mealybug (Hemiptera: Coccoidea: Pseudococcidae) pest in Florida and the Caribbean : the papaya mealybug, Paracoccus marginatus Williams and Granara de Willink

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    Paracoccus marginatus Williams and Granara de Willink, here called the papaya mealybug, was first detected in the United States in Hollywood, Florida in 1998. By the end of 1998 it was found in four localities in the state and has since spread to nine localities in five counties. This mealybug appears to have moved through the Caribbean area since its 1994 detection in the Dominican Republic. The pest is reported to cause serious damage to tropical fruit, especially papaya, and has been detected most frequently, in Florida, on hibiscus. It is now known from Antigua, Belize, the British Virgin Islands, Costa Rica, Guatemala, Mexico, Nevis, Puerto Rico, St. Barthelemy, St. Kitts, St. Martin, and the US Virgin Islands. Hosts include: Acacia sp.(Luguminosae), Acalypha sp.(Euphorbiaceae), Ambrosia cumanensis (Compositae), Annona squamosa (Annonaceae), Carica papaya (Caricaceae), Guazuma ulmifolia (Sterculiaccea), Hibiscus rosa-sinensis (Euphorbiaceae), Hibiscus sp. (Euphorbiaceae), Ipomoea sp. (Convolvulaceae), Manihot chloristica (Euphorbiaceae), Manihot esculenta (Euphorbiaceae), Mimosa pigra (Lugiminosae), Parthenium hysterophorus (Compositae), Persea americana (Lauraceae), Plumeria sp. (Apocynaceae), Sida sp. (Malvaceae), Solanum melongena (Solanaceae). The species is believed to be native to Mexico andlor Central America

    Advanced Extravehicular Protective Systems (AEPS) study

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    A description is given of life support subsystem concepts for advanced extravehicular protective systems (AEPS) intended for use on future orbital, lunar surface, and Mars surface missions in the late 1970's and 1980's. Primary interest was centered around the thermal control and carbon dioxide control subsystems because they offer the greatest potential for total weight savings. Emphasis was placed on the generation of regenerable subsystem concepts; however, partially regenerable and expendable concepts were also considered. Previously conceived and developed subsystem concepts were included in the study. Concepts were evaluated on the basis of subsystem weight and volume, and subsystem contribution to parent vehicle weight and volume, which included spares, regeneration equipment, expendables, expandables storage penalty, power penalty, and process heating or cooling penalty. Results are presented showing total weight and volume penalty as a function of total mission extravehicular activity (EVA) hours, and showing EVA weight and volume as a function of EVA duration. Subsystem concepts are recommended for each life support function, and secondary concepts which should be developed are also identified

    THE EFFECT OF STEREOTYPE ON COGNITIVE PERFORMANCE: AN EXPERIMENTAL STUDY OF FEMALE COGNITIVE PERFORMANCE

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    This study investigated the effect stereotypes have on cognitive performance. A between-subjects experimental design was utilized in the study. Forty participants from the senior secondary two (SS2) of Chapel Secondary School Ilorin took part in the study, and their cognitive performance in the light of exposure to a stereotype was measured. Four hypotheses were tested. Using the t-test for independent samples, the findings of the experiment showed that males performed better than females on a mathematics test when exposed to stereotype (t=2.688, df=l8, p<O.OS). The study also found that males who were exposed to stereotype performed better than males who were not exposed to stereotype (t=2.998, df=l8, p< 0.05). However, there was no significant difference in the performance of females who were exposed to stereotype and those who were not (t=2.740, df=l8, p>O.OS). Stereotypes have been identified to affect the way people see things and the way they interpret certain behaviours of other individuals or groups. Therefore understanding the nature of stereotypes, prejudice, and discrimination is the first step in combating these practices

    Regenerable thermal control and carbon dioxide control techniques for use in advanced extravehicular protective systems

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    The most promising closed CO2 control concept identified by this study is the solid pellet, Mg(OH2)2 system. Two promising approaches to closed thermal control were identified. The AHS system uses modular fusible heat sinks, with a contingency evaporative mode, to allow maximum EVA mobility. The AHS/refrigerator top-off subsystem requires an umbilical to minimize expendables, but less EVA time is used to operate the system, since there is no requirement to change modules. Both of these subsystems are thought to be practical solutions to the problem of providing closed heat rejection for an EVA system

    Choosing embryos: Ethical complexity and relational autonomy in staff accounts of PGD

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    Copyright @ 2008 the authors. This article is available in accordance with the Creative Commons Deed, Attribution 2.5, see http://creativecommons.org/licenses/by-nc-nd/2.5/deed.en_CA.The technique of preimplantation genetic diagnosis (PGD) is commonly explained as a way of checking the genes of embryos produced by IVF for serious genetic diseases. However, complex accounts of this technique emerged during ethics discussion groups held for PGD staff. These form part of a study exploring the social processes, meanings and institutions that frame and produce ‘ethical problems’ for practitioners, scientists and others working in the specialty of PGD in the UK. Two ‘grey areas’ raised by staff are discussed in terms of how far staff are, or in the future may be, able to support autonomous choices of women/couples: accepting ‘carrier’ embryos within the goal of creating a ‘healthy’ child; and sex selection of embryos for social reasons. These grey areas challenged the staff’s resolve to offer individual informed choice, in the face of their awareness of possible collective social effects that might ensue from individual choices. We therefore argue that these new forms of choice pose a challenge to conventional models of individual autonomy used in UK genetic and reproductive counselling, and that ‘relational autonomy’ may be a more suitable ethical model to describe the ethical principles being drawn on by staff working in this area.The Wellcome Trust Biomedical Ethics Programme, who funded the project ‘Facilitating choice, framing choice: the experience of staff workingin pre-implantation genetic diagnosis’ (no: 074935)

    Start-to-end modelling of a mode-locked optical klystron free electron laser amplifier

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    A free electron laser (FEL) in a mode-locked optical klystron (MLOK) configuration is modelled using start-to-end simulations that simulate realistic electron beam acceleration and transport before input into a full three-dimensional FEL simulation code. These simulations demonstrate that the MLOK scheme is compatible with the present generation of radiofrequency accelerator designs. A train of few-optical cycle pulses is predicted with peak powers similar to those of the equivalent conventional FEL amplifier. The role of electron beam energy modulation in these results is explained and the limitations of some simulation codes discussed. It is shown how seeding the FEL interaction using a High Harmonic seed laser can improve the coherence properties of the output

    How to do realistic political theory (and why you might want to)

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    In recent years, a number of realist thinkers have charged much contemporary political theory with being idealistic and moralistic. While the basic features of the realist counter-movement are reasonably well understood, realism is still considered a critical, primarily negative creed which fails to offer a positive, alternative way of thinking normatively about politics. Aiming to counteract this general perception, in this article I draw on Bernard Williams’s claims about how to construct a politically coherent conception of liberty from the non-political value of freedom. I do this because Williams’s argument provides an illuminating example of the distinctive nature of realist political thinking and its attractions. I argue that Williams’s account of realist political thinking challenges the orthodox moralist claim that normative political arguments must be guided by an ideal ethical theory. I then spell out the repercussions Williams’s claims about the significance of political opposition and non-moralised accounts of motivation have for our understanding of the role and purpose of political theory. I conclude by defending the realist claim that action-guiding political theory should accordingly take certain features of our politics as given, most centrally the reality of political opposition and the passions and experiences that motivate them. On this reading political realism offers a viable way of thinking about political values which cannot be understood in terms of the categories of intellectual separation – ideal/nonideal or fact-insensitive/fact-sensitive – that have marked political theory in recent years
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