WorldWideScience

Sample records for lenses important questions

  1. Fifty important research questions in microbial ecology.

    Science.gov (United States)

    Antwis, Rachael E; Griffiths, Sarah M; Harrison, Xavier A; Aranega-Bou, Paz; Arce, Andres; Bettridge, Aimee S; Brailsford, Francesca L; de Menezes, Alexandre; Devaynes, Andrew; Forbes, Kristian M; Fry, Ellen L; Goodhead, Ian; Haskell, Erin; Heys, Chloe; James, Chloe; Johnston, Sarah R; Lewis, Gillian R; Lewis, Zenobia; Macey, Michael C; McCarthy, Alan; McDonald, James E; Mejia-Florez, Nasmille L; O'Brien, David; Orland, Chloé; Pautasso, Marco; Reid, William D K; Robinson, Heather A; Wilson, Kenneth; Sutherland, William J

    2017-05-01

    Microbial ecology provides insights into the ecological and evolutionary dynamics of microbial communities underpinning every ecosystem on Earth. Microbial communities can now be investigated in unprecedented detail, although there is still a wealth of open questions to be tackled. Here we identify 50 research questions of fundamental importance to the science or application of microbial ecology, with the intention of summarising the field and bringing focus to new research avenues. Questions are categorised into seven themes: host-microbiome interactions; health and infectious diseases; human health and food security; microbial ecology in a changing world; environmental processes; functional diversity; and evolutionary processes. Many questions recognise that microbes provide an extraordinary array of functional diversity that can be harnessed to solve real-world problems. Our limited knowledge of spatial and temporal variation in microbial diversity and function is also reflected, as is the need to integrate micro- and macro-ecological concepts, and knowledge derived from studies with humans and other diverse organisms. Although not exhaustive, the questions presented are intended to stimulate discussion and provide focus for researchers, funders and policy makers, informing the future research agenda in microbial ecology. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. 75 FR 53971 - Guidance for Industry and Food and Drug Administration Staff; Impact-Resistant Lenses: Questions...

    Science.gov (United States)

    2010-09-02

    ... DEPARTMENT OF HEALTH AND HUMAN SERVICES Food and Drug Administration [Docket No. FDA-2007-D-0367] Guidance for Industry and Food and Drug Administration Staff; Impact-Resistant Lenses: Questions and Answers; Availability AGENCY: Food and Drug Administration, HHS. ACTION: Notice. SUMMARY: The Food and...

  3. [Importance of asferic treatment of intraocular lenses in contrast sensitivity of the human eye].

    Science.gov (United States)

    Calţaru, Dana Cristina; Pop, Mihai

    2014-01-01

    Clinical study which follows the influence of asphericity of intraocular lenses on an important parameter of quality of vision in operated cataract patients - contrast sensibility. This is a pilot, prospective study with 131 eyes of 124 patients, which had cataract surgery by phacoemulsification between 2011-2012. All operations were done by the same surgeon. EXCLUSION CRITERIAS WERE: VA ( 0.7; postop refraction >0.75 D sf. or 0.75 D cyl, corneal diseases, optic nerv or retinal pathologies, atypical surgery, pupil diameter 3 mm. Postoperative control was done at six weeks and included : AV, optical correction, contrast sensibility testing, intraocular pressure, posterior pol exam. Contrast sensibility testing was done using a LCD device, in fotopic condition, CC-100 TOPCON. Contrast sensibility graphics were compared between spheric and aspheric lenses for Zeiss, AMO, Bausch&Lomb, Alcon. There were no statistically significant differences between aspherical lenses. Also, there were no differences for the same manufacturer between spherical and aspherical lenses.

  4. Chemical Manufacturers, Importers, and Exporters: Frequent Questions

    Science.gov (United States)

    Chemical manufacturers, importers, and exporters are required to operate within a system of allowances. This information will help those in the chemical industry understand their role in the phaseout of HCFCs in the United States.

  5. Gravitational lensing of quasars

    CERN Document Server

    Eigenbrod, Alexander

    2013-01-01

    The universe, in all its richness, diversity and complexity, is populated by a myriad of intriguing celestial objects. Among the most exotic of them are gravitationally lensed quasars. A quasar is an extremely bright nucleus of a galaxy, and when such an object is gravitationally lensed, multiple images of the quasar are produced – this phenomenon of cosmic mirage can provide invaluable insights on burning questions, such as the nature of dark matter and dark energy. After presenting the basics of modern cosmology, the book describes active galactic nuclei, the theory of gravitational lensing, and presents a particular numerical technique to improve the resolution of astronomical data. The book then enters the heart of the subject with the description of important applications of gravitational lensing of quasars, such as the measurement of the famous Hubble constant, the determination of the dark matter distribution in galaxies, and the observation of the mysterious inner parts of quasars with much higher r...

  6. The Importance of Asking Questions – in Different Ways! Most ...

    Indian Academy of Sciences (India)

    IAS Admin

    Zare, Professor of Chemistry at Stanford University, USA. He said: “The question is a central aspect of both learning and knowledge creation. Yet students often seem to value more the answer than the question. I think quite the opposite. The quest to answer a question is where the learning takes place, not the answer itself”.

  7. The Importance of Asking Questions – in Different Ways! Most ...

    Indian Academy of Sciences (India)

    IAS Admin

    Did you learn anything today? But not my mother. “Izzy,” she would say, “did you ask a good question today?” That difference — asking good questions — made me become a scientist.” And what kind of scientist did he become? He was. Isidor Isaac Rabi, who worked in the Physics department in. Columbia University, USA.

  8. Importance of questionnaire context for a physical activity question

    DEFF Research Database (Denmark)

    Jørgensen, M. E.; Sørensen, Mette Rosenlund; Ekholm, O.

    2013-01-01

    Adequate information about physical activity habits is essential for surveillance, implementing, and evaluating public health initiatives in this area. Previous studies have shown that question order and differences in wording result in systematic differences in people's responses to questionnaires......; however, this has never been shown for physical activity questions. The aim was to study the influence of different formulations and question order on self-report physical activity in a population-based health interview survey. Four samples of each 1000 adults were drawn at random from the National Person...

  9. Key research questions of global importance for cetacean conservation

    Science.gov (United States)

    Parsons, E. C. M.

    2016-02-01

    Limited resources and increasing environmental concerns have prompted calls to identify the critical questions that most need to be answered to advance conservation, thereby providing an agenda for scientific research priorities. Cetaceans are often keystone indicator species but also high profile, charismatic flagship taxa that capture public and media attention as well as political interest. A dedicated workshop was held at the conference of the Society for Marine Mammalogy (December 2013, New Zealand) to identify where lack of data was hindering cetacean conservation and which questions need to be addressed most urgently. This paper summarizes 15 themes and component questions prioritized during the workshop. We hope this list will encourage cetacean conservation-orientated research and help agencies and policy makers to prioritize funding and future activities. This will ultimately remove some of the current obstacles to science-based cetacean conservation.

  10. How Pollination Ecology research can help answer important questions

    Directory of Open Access Journals (Sweden)

    Carvalheiro, Luisa G.

    2011-06-01

    Full Text Available Pollination Ecology is a dynamic field of scientific research constantly adopting novel methods and making progress in understanding the interactions between plants and their pollinators. A recent paper listed the main scientific questions in this field focussing on the ecological and biological system itself. Here, we follow up on that paper and present some ideas on how to broaden our perspective and explore the role that pollination research can play in answering both ecological and societal questions relevant to a range of different stakeholders. We hope this paper may be useful to researchers aiming at improving both the scientific and societal impact of their research.

  11. Secondary Data Analysis: An Important Tool for Addressing Developmental Questions

    Science.gov (United States)

    Greenhoot, Andrea Follmer; Dowsett, Chantelle J.

    2012-01-01

    Existing data sets can be an efficient, powerful, and readily available resource for addressing questions about developmental science. Many of the available databases contain hundreds of variables of interest to developmental psychologists, track participants longitudinally, and have representative samples. In this article, the authors discuss the…

  12. Gravitational lensing

    CERN Document Server

    Dodelson, Scott

    2017-01-01

    Gravitational lensing is a consequence of general relativity, where the gravitational force due to a massive object bends the paths of light originating from distant objects lying behind it. Using very little general relativity and no higher level mathematics, this text presents the basics of gravitational lensing, focusing on the equations needed to understand the phenomena. It then applies them to a diverse set of topics, including multiply imaged objects, time delays, extrasolar planets, microlensing, cluster masses, galaxy shape measurements, cosmic shear, and lensing of the cosmic microwave background. This approach allows undergraduate students and others to get quickly up to speed on the basics and the important issues. The text will be especially relevant as large surveys such as LSST and Euclid begin to dominate the astronomical landscape. Designed for a one semester course, it is accessible to anyone with two years of undergraduate physics background.

  13. Inverting Gravitational Lenses

    Science.gov (United States)

    Newbury, P. R.; Spiteri, R. J.

    2002-02-01

    Gravitational lensing provides a powerful tool to study a number of fundamental questions in astrophysics. Fortuitously, one can begin to explore some non-trivial issues associated with this phenomenon without a lot of very sophisticated mathematics, making an elementary treatment of this topic tractable even to senior undergraduates. In this paper, we give a relatively self-contained outline of the basic concepts and mathematics behind gravitational lensing as a recent and exciting topic for courses in mathematical modeling or scientific computing. To this end, we have designed and made available some interactive software to aid in the simulation and inversion of gravitational lenses in a classroom setting.

  14. [Implantation of intraocular lenses. Bullous keratopathy in pseudophakos].

    Science.gov (United States)

    Alberth, B

    1982-09-01

    The author presents his views on the implantation of intraocular lenses, in connection with two pseudophakic bullous keratopathy cases. There is no medical indication for implantation. The question is whether the most important function of the eye, object vision, may be risked in order to avoid aniseikonia or to restore binocular vision? Knowing that vision can be restored with glasses or contact lenses, is it ethical to induce more or less severe postoperative complications by means of intraocular lenses? In view of the considerable success often achieved immediately after the operation, complications which may not arise years later should also be taken into consideration.

  15. Divorce or Continue Marriage for Child? An Important Question about Psychological Adjustment of Child

    Directory of Open Access Journals (Sweden)

    Nilgun Ongider Gregory

    Full Text Available This study focused on finding answers about an important question that parents are recently asking psychological professionals. This question has become more relevant in the last couple of decades as there are increasing divorce rates in Turkey and the rest of the world. Because of this reason, parents are asking the important question: is it better for our child to divorce or continue our marriage? Researchers come up with very different results to this question. They need to not only focus on the effects of divorce itself but also need to examine the quality of the relationship between the parents. Parents need to remember this very important point that divorce is not the only thing that effects children's psychological adjustment by itself. So, the answer of the question to divorce or stay together is answered by the amount of parental conflict and the quality of the parent's relationship. As a result, the ideal environment for children's psychological development is living with both parents in the same household and having a low-conflict parents. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2016; 8(3.000: 275-289

  16. Frequent Questions about the Hazardous Waste Export-Import Revisions Final Rule

    Science.gov (United States)

    Answers questions such as: What new requirements did EPA finalize in the Hazardous Waste Export-Import Revisions Final Rule? Why did EPA implement these changes now? What are the benefits of the final rule? What are the compliance dates for the final rule?

  17. Questions of importance to the conservation of biological diversity: answers from the past

    Directory of Open Access Journals (Sweden)

    K. J. Willis

    2010-11-01

    Full Text Available Paleoecological records are replete with examples of biotic responses to past climate change and human impact, but how can we use these records in the conservation of current and future biodiversity? A recently published list of (One Hundred Questions of Importance to the Conservation of Global Biological Diversity (Sutherland et al., 2009 highlights a number of key research questions that need a temporal perspective. Many of these questions are related to the determination of ecological processes in order to assess ecosystem function and services, climate change-integrated conservation strategies, and ecosystem management and restoration. However, it is noticeable that not a single contributor to this list was from the paleo-research community and that extremely few paleo-records are ever used in the development of terrestrial conservation management plans. This lack of dialogue between conservationists and the paleo-community is partially driven by a perception that the data provided by paleoecological records are purely descriptive and not of relevance to the day-to-day management and conservation of biological diversity. This paper illustrates, through a series of case-studies, how long-term ecological records (>50 years can provide a test of predictions and assumptions of ecological processes that are directly relevant to management strategies necessary to retain biological diversity in a changing climate. This discussion paper includes information on diversity baselines, thresholds, resilience, and restoration of ecological processes.

  18. The 150 most important questions in cancer research and clinical oncology series: questions 15-24 : Edited by Chinese Journal of Cancer.

    Science.gov (United States)

    2017-04-05

    To accelerate our endeavors to overcome cancer, Chinese Journal of Cancer has launched a program of publishing 150 most important questions in cancer research and clinical oncology. In this article, 10 more questions are presented as follows. Question 15: Can tumor-induced erythrogenesis provide qualified red blood cells for carrying oxygen to distant organs? Question 16: Can we overcome tumor resistance to platinum-containing antineoplastic drugs by activating the sensitivity factors in the tumor? Question 17: How can a cancer cell stay dormant for years? Question 18: Why do cancer cells use distinct transcriptomic and proteomic programs to reach the same metastatic phenotype? Question 19: Why do some cancers regress spontaneously? Question 20: What are the regulatory mechanisms occurring in donor cells that determine selective sorting of biological content into vesicles and their biological consequences in recipient cells? Are the genetic transfer and exchange of biological messages between cells transient? Is the phenotypic manipulation of recipient cells temporary or prolonged and persistent? If extracellular vesicles possess immune-modulatory potential, how could they be exploited for immune interventions and cancer immunotherapy? Presumably the cargo of extracellular vesicles reflects the cells of their origin and can be used for cancer diagnosis, how could the uniform/stringent capture criteria be met universally for applying EVs in point-of-care diagnostics for cancer patients? Question 21: Can we use self-sampling technologies to monitor the tumor genetic alterations for more precise targeted therapy? Can we cure a heterogeneous tumor by sequentially targeting the driver molecules? Question 22: Can we postpone the onset of non-infection-related cancers? Question 23: How many types of cells can jointly form the tumor vasculature to provide blood supply for tumor progression? Question 24: How tumor cells transmit their epigenetic features to daughter cells

  19. Acoustic lenses

    International Nuclear Information System (INIS)

    Kittmer, C.A.

    1983-03-01

    Acoustic lenses focus ultrasound to produce pencil-like beams with reduced near fields. When fitted to conventional (flat-faced) transducers, such lenses greatly improve the ability to detect and size defects. This paper describes a program developed to design acoustic lenses for use in immersion or contact inspection, using normal or angle beam mode with flat or curved targets. Lens surfaces are circular in geometry to facilitate machining. For normal beam inspection of flat plate, spherical or cylindrical lenses are used. For angle beam or curved surface inspections, a compound lens is required to correct for the extra induced aberration. Such a lens is aspherical with one radius of curvature in the plane of incidence, and a different radius of curvature in the plane perpendicular to the incident plane. The resultant beam profile (i.e., location of the acoustic focus, beam diameter, 6 dB working range) depends on the degree of focusing and the transducer used. The operating frequency and bandwidth can be affected by the instrumentation used. Theoretical and measured beam profiles are in good agreement. Various applications, from zone focusing used for defect sizing in thick plate, to line focusing for pipe weld inspection, are discussed

  20. Seventy-One Important Questions for the Conservation of Marine Biodiversity

    Science.gov (United States)

    PARSONS, E C M; FAVARO, BRETT; AGUIRRE, A ALONSO; BAUER, AMY L; BLIGHT, LOUISE K; CIGLIANO, JOHN A; COLEMAN, MELINDA A; CÔTÉ, ISABELLE M; DRAHEIM, MEGAN; FLETCHER, STEPHEN; FOLEY, MELISSA M; JEFFERSON, REBECCA; JONES, MIRANDA C; KELAHER, BRENDAN P; LUNDQUIST, CAROLYN J; MCCARTHY, JULIE-BETH; NELSON, ANNE; PATTERSON, KATHERYN; WALSH, LESLIE; WRIGHT, ANDREW J; SUTHERLAND, WILLIAM J

    2014-01-01

    The ocean provides food, economic activity, and cultural value for a large proportion of humanity. Our knowledge of marine ecosystems lags behind that of terrestrial ecosystems, limiting effective protection of marine resources. We describe the outcome of 2 workshops in 2011 and 2012 to establish a list of important questions, which, if answered, would substantially improve our ability to conserve and manage the world’s marine resources. Participants included individuals from academia, government, and nongovernment organizations with broad experience across disciplines, marine ecosystems, and countries that vary in levels of development. Contributors from the fields of science, conservation, industry, and government submitted questions to our workshops, which we distilled into a list of priority research questions. Through this process, we identified 71 key questions. We grouped these into 8 subject categories, each pertaining to a broad component of marine conservation: fisheries, climate change, other anthropogenic threats, ecosystems, marine citizenship, policy, societal and cultural considerations, and scientific enterprise. Our questions address many issues that are specific to marine conservation, and will serve as a road map to funders and researchers to develop programs that can greatly benefit marine conservation. Setenta y Un Preguntas Importantes para la Conservación de la Biodiversidad Marina Resumen Los océanos proporcionan alimento, actividad económica y valor cultural para una gran porción de la humanidad. Nuestro conocimiento de los ecosistemas marinos está atrasado con respecto al que tenemos de los ecosistemas terrestres, lo que limita la protección efectiva de los recursos naturales. Describimos el resultado de dos talleres en 2011 y 2012 para establecer una lista de preguntas importantes, las cuales al ser respondidas, mejorarían sustancialmente nuestra habilidad de conservar y manejar los recursos marinos del mundo. Entre los

  1. Gravitational lenses and cosmological evolution

    International Nuclear Information System (INIS)

    Peacock, J.A.

    1982-01-01

    The effect of gravitational lensing on the apparent cosmological evolution of extragalactic radio sources is investigated. Models for a lens population consisting of galaxies and clusters of galaxies are constructed and used to calculate the distribution of amplification factors caused by lensing. Although many objects at high redshifts are predicted to have flux densities altered by 10 to 20 per cent relative to a homogeneous universe, flux conservation implies that de-amplification is as common as amplification. The effects on cosmological evolution as inferred from source counts and redshift data are thus relatively small; the slope of the counts is not large enough for intrinsically rare lensing events of high amplitude to corrupt observed samples. Lensing effects may be of greater importance for optically selected quasars, where lenses of mass as low as approximately 10 -4 solar mass can cause large amplifications. (author)

  2. Gravitational lenses and. cosmological evolution

    Science.gov (United States)

    Peacock, J. A.

    1982-06-01

    The effect of gravitational lensing on the apparent evolution of extragalactic radio sources is investigated. Models for a lens population consisting of galaxies and clusters of galaxies are constructed used to calculate the distribution of amplification factors caused by lensing ,. Although many objects at high redshifts are predicted to have flux densities altered by 10-20 per cent relative to a homogeneous universe, flux conservation implies that de-amplification is as common as amplification. The effect on cosmological evolution as inferred from source counts and redshift data are thus relatively small; the slope of the counts is not large enough for intrinsically rare lensing events of high amplitude to corrupt observed sample Lensing effects may be of greater importance for optically selected quasar where lenses of mass as low as ˜10-4 Msun can cause large amplifications.

  3. The nuclear question: rethinking species importance in multi-species animal groups.

    Science.gov (United States)

    Srinivasan, Umesh; Raza, Rashid Hasnain; Quader, Suhel

    2010-09-01

    shaping species importance. 5. Our view of nuclearity provides predictive power in examining species roles in a variety of situations (e.g. predicting leadership in differently composed communities), and can be applied to examine a broad range of ecological and evolutionary questions pertinent to multi-species groups in general.

  4. NAFTA Guidance on Data Requirements for Pesticide Import Tolerances: Questions & Answers

    Science.gov (United States)

    These Qs&As provide details of implementation related to a guidance document describing the data requirements for establishing pesticide import tolerances in Canada and the United States: NAFTA Guidance on Data Requirements for Pesticide Import Tolerances.

  5. The top 100 questions of importance to the future of global agriculture

    NARCIS (Netherlands)

    Pretly, J.; Sutherland, W.J.; Ashby, J.; Auburn, J.; Baulcombe, D.; Bell, M.; Bentley, J.; Bickersteth, S.; Brown, K.; Burke, J.; Campbell, H.; Chen, K.; Crowley, E.; Crute, I.; Dobbelaere, D.; Edwards-Jones, G.; Funes-Monzote, F.; Godfray, H.C.J.; Griffon, M.; Gypmantisiri, P.; Haddad, L.; Halavatau, S.; Herren, H.; Holderness, M.; Izac, A.M.; Jones, M.; Koohafkan, P.; Lal, R.; Lang, T.; McNeely, J.; Mueller, A.; Nisbett, N.; Noble, A.; Pingali, P.; Pinto, Y.; Rabbinge, R.; Ravindranath, N.H.; Rola, A.; Röling, N.G.; Sage, C.; Settle, W.; Sha, J.M.; Luo, S.M.; Simons, T.; Smith, P.; Strzepeck, K.; Swaine, H.; Terry, E.; Tomich, T.P.; Toulmin, C.; Trigo, E.; Twomlow, S.; Vis, J.K.; Wilson, J.; Pilgrim, S.

    2010-01-01

    Despite a significant growth in food production over the past half-century, one of the most important challenges facing society today is how to feed an expected population of some nine billion by the middle of the 20th century. To meet the expected demand for food without significant increases in

  6. Radiosensitivity of the developing central nervous system: an important question in radiation protection

    International Nuclear Information System (INIS)

    Perez, Maria del R.; Gisone, Pablo A.; Dubner, Diana L.; Robello, Elizabeth; Michelin, Severino C.

    2004-01-01

    The high radiosensitivity of the human developing brain has been demonstrated by epidemiological data . The maximal incidence of microcephaly and mental retardation in the Hiroshima and Nagasaki cohort was observed among survivors exposed between 8 and 15 weeks of gestation. Experimental studies indicate that this period corresponds to gestational days (g.d.) 14-18 in the rat. Apoptosis, the typical mode of radiation-induced cell death in developing Central Nervous System (CNS), is closely related with the oxidative status. Enhanced radiation-induced generation of reactive oxygen and nitrogen species (ROS/RNS) has been observed after low-dose radiation exposure, leading to the amplification of signal transduction and further molecular and cellular radiation-responses. This study is an attempt to address the participation of ROS/RNS in the early radiation-induced apoptosis of neural cortical precursors. Cortical cells obtained from Wistar rat fetuses at 17 g.d. were irradiated with a dose of 2 Gy at a dose-rate of 0.3 Gy/minute. Nitric oxide (NO) content estimated by measuring the stable products NO 2 and NO 3 released to the culture medium, has shown a time-dependent accumulation from 30 min post-irradiation (pi). ROS/RNS content was determined by luminol-dependent chemiluminescence. A significant decrease of chemiluminescence was evident 30 min pi, reaching basal levels at 120 min, followed by an important augmentation by 4 hs after irradiation. The early decrease in ROS/RNS was not observed in samples irradiated in the presence of L-NAME, an inhibitor of nitric oxide synthase. Incubations with superoxide dismutase (SOD) and catalase (CAT) decreased significantly the chemiluminescence in irradiated samples. Apoptotic cell death, already evident from 4 hs pi., was significantly increased in irradiated cells after incubation with L-NAME. We conclude that ROS/RNS play a pivotal role in the early signaling pathway leading to a radiation-induced cell death of cortical

  7. Importance of Broken Gauge Symmetry in Addressing Three, Key, Unanswered Questions Posed by Low Nuclear Reactions (LENR's)

    Science.gov (United States)

    Chubb, Scott

    2003-03-01

    Three, Key, Unanswered Questions posed by LENR's are: 1. How do we explain the lack of high energy particles (HEP's)? 2. Can we understand and prioritize the way coupling can occur between nuclear- and atomic- lengthscales, and 3. What are the roles of Surface-Like (SL), as opposed to Bulk-Like (BL), processes in triggering nuclear phenomena. One important source of confusion associated with each of these questions is the common perception that the quantum mechanical phases of different particles are not correlated with each other. When the momenta p of interacting particles is large, and reactions occur rapidly (between HEP's, for example), this is a valid assumption. But when the relative difference in p becomes vanishingly small, between one charge, and many others, as a result of implicit electromagnetic coupling, each charge can share a common phase, relative to the others, modulo 2nπ, where n is an integer, even when outside forces are introduced. The associated forms of broken gauge symmetry, distinguish BL from SL phenomena, at room temperature, also explain super- and normal- conductivity in solids, and can be used to address the Three, Key, Unanswered Questions posed by LENR's.

  8. Arcs from gravitational lensing

    Science.gov (United States)

    Grossman, Scott A.; Narayan, Ramesh

    1988-01-01

    The proposal made by Paczynski (1987) that the arcs of blue light found recently in two cluster cores are gravitationally lensed elongated images of background galaxies is investigated. It is shown that lenses that are circularly symmetric in projection produce pairs of arcs, in conflict with the observations. However, more realistic asymmetric lenses produce single arcs, which can become as elongated as the observed ones whenever the background galaxy is located on or close to a cusp caustic. Detailed computer simulations of lensing by clusters using a reasonable model of the mass distribution are presented. Elongated and curved lensed images longer than 10 arcsec occur in 12 percent of the simulated clusters. It is concluded that the lensing hypothesis must be taken seriously.

  9. Processes for manufacturing multifocal diffractive-refractive intraocular lenses

    Science.gov (United States)

    Iskakov, I. A.

    2017-09-01

    Manufacturing methods and design features of modern diffractive-refractive intraocular lenses are discussed. The implantation of multifocal intraocular lenses is the most optimal method of restoring the accommodative ability of the eye after removal of the natural lens. Diffractive-refractive intraocular lenses are the most widely used implantable multifocal lenses worldwide. Existing methods for manufacturing such lenses implement various design solutions to provide the best vision function after surgery. The wide variety of available diffractive-refractive intraocular lens designs reflects the demand for this method of vision correction in clinical practice and the importance of further applied research and development of new technologies for designing improved lens models.

  10. Gravitational lensing and microlensing

    CERN Document Server

    Mollerach, Silvia

    2002-01-01

    This book provides a comprehensive and self-contained exposition of gravitational lensing phenomena. It presents the up-to-date status of gravitational lensing and microlensing, covering the cosmological applications of the observed lensing by galaxies, clusters and the large scale structures, as well as the microlensing searches in the Local Group and its applications to unveil the nature of the galactic dark matter, the search for planetary objects and the distribution of faint stars in our galaxy. Gravitational Lensing and Microlensing is pitched at the level of the graduate student interes

  11. Weak lensing and cosmological investigation

    CERN Document Server

    Acquaviva, V

    2005-01-01

    In the last few years the scientific community has been dealing with the challenging issue of identifying the dark energy component. We regard weak gravitational lensing as a brand new, and extremely important, tool for cosmological investigation in this field. In fact, the features imprinted on the cosmic microwave background radiation by the lensing from the intervening distribution of matter represent a pretty unbiased estimator, and can thus be used for putting constraints on different dark energy models. This is true in particular for the magnetic-type B-modes of CMB polarization, whose unlensed spectrum at large multipoles (l approximately=1000) is very small even in presence of an amount of gravitational waves as large as currently allowed by the experiments: therefore, on these scales the lensing phenomenon is the only responsible for the observed power, and this signal turns out to be a faithful tracer of the dark energy dynamics. We first recall the formal apparatus of the weak lensing in extended t...

  12. Learning through Different Lenses

    Science.gov (United States)

    Jeweler, Sue; Barnes-Robinson, Linda

    2015-01-01

    When parents and teachers help gifted kids use the metaphor "learning through different lenses," amazing things happen: Horizons open up. Ideas are focused. Thoughts are magnified and clarified. They see the big picture. Metaphoric thinking offers new and exciting ways to see the world. Viewing the world through different lenses provides…

  13. Modern scleral lenses: Mini versus large.

    Science.gov (United States)

    Fadel, Daddi

    2017-08-01

    The evolution of scleral lenses has led to new formulations of scleral fitting concepts and designs. The diameters of modern scleral lenses have been overhauled too and they are smaller comparing to the original ones. Nowadays, prescription of mini-sclerals supposedly seems in major extension and it appears indeed the necessity of some practitioner to differentiate the smaller mini-scleral lenses from larger mini-scleral lenses empathizing that they are the "smaller" ones. Therefore, it is maybe, necessary a definition of mini-scleral lenses referring to the landing zone width in relation to the horizontal visible iris diameter (HVID) and the limbus extension. The choice of the total diameter is crucial for a successful fitting and it depends majorly on patient's topographic patterns and anatomic factors. However, there are other important criteria for the selection of the scleral lens diameter based on oxygen supply, bubbles formation, mechanical stress on a toric sclera, ocular surface disease protection, entity of the vault over the cornea and distribution of the lens weight on the sclera. The advantages of mini-scleral lenses are various nonetheless in some cases large lenses are necessary. This paper presents a review of the benefits and disadvantages of both mini and large scleral lenses analyzing the conditions in which it may be better to prefer one diameter to another. A suggestion may be that to start fitting the smallest lens as possible, depending on the dimension of HVID and limbus width and consider larger lenses only when issues occur. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  14. Thirty Meter Telescopes and Gravitational Lensing

    OpenAIRE

    Carlberg, R. G.

    2004-01-01

    Diffraction limited 30m class telescopes will play an important role in gravitational lensing studies, coming online in approximately 2015. As imaging telescopes they will complement the ~6m JWST, probing to smaller angular scales in greatly magnified objects near critical lines and for measuring shear of objects below the JWST angular scale, such as luminous super-star clusters at high redshift. The high source density will allow more detailed mass mapping in the weak lensing regime and will...

  15. EDITORIAL: Focus on Gravitational Lensing

    Science.gov (United States)

    Jain, Bhuvnesh

    2007-11-01

    Gravitational lensing emerged as an observational field following the 1979 discovery of a doubly imaged quasar lensed by a foreground galaxy. In the 1980s and '90s dozens of other multiply imaged systems were observed, as well as time delay measurements, weak and strong lensing by galaxies and galaxy clusters, and the discovery of microlensing in our galaxy. The rapid pace of advances has continued into the new century. Lensing is currently one of best techniques for finding and mapping dark matter over a wide range of scales, and also addresses broader cosmological questions such as understanding the nature of dark energy. This focus issue of New Journal of Physics presents a snapshot of current research in some of the exciting areas of lensing. It provides an occasion to look back at the advances of the last decade and ahead to the potential of the coming years. Just about a decade ago, microlensing was discovered through the magnification of stars in our galaxy by invisible objects with masses between that of Jupiter and a tenth the mass of the Sun. Thus a new component of the mass of our galaxy, dubbed MACHOs, was established (though a diffuse, cold dark matter-like component is still needed to make up most of the galaxy mass). More recently, microlensing led to another exciting discovery—of extra-solar planets with masses ranging from about five times that of Earth to that of Neptune. We can expect many more planets to be discovered through ongoing surveys. Microlensing is the best technique for finding Earth mass planets, though it is not as productive overall as other methods and does not allow for follow up observations. Beyond planet hunting, microlensing has enabled us to observe previously inaccessible systems, ranging from the surfaces of other stars to the accretion disks around the black holes powering distant quasars. Galaxies and galaxy clusters at cosmological distances can produce dramatic lensing effects: multiple images of background galaxies

  16. Nanofocusing refractive X-ray lenses

    International Nuclear Information System (INIS)

    Boye, Pit

    2010-01-01

    This thesis is concerned with the optimization and development of the production of nanofocusing refractive X-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution X-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high precision, high quality and high piece number. Furthermore a process for the production of diamond lenses is to be developed and established. In this work, the theoretical basics of X-rays and their interaction with matter are described. Especially, aspects of synchrotron radiation are emphasized. Important in X-ray microscopy are the different optics. The details, advantages and disadvantages, in particular those of refractive lenses are given. To achieve small X-ray beams well beyond the 100 nm range a small focal length is required. This is achieved in refractive lenses by moving to a compact lens design where several single lenses are stacked behind each other. The, so-called nanofocusing refractive lenses (NFLs) have a parabolic cylindrical shape with lateral structure sizes in the micrometer range. NFLs are produced by using micro-machining techniques. These micro-fabrication processes and technologies are introduced. The results of the optimization and the final fabrication process for silicon lenses are presented. Subsequently, two experiments that are exemplary for the use of NFLs, are introduced. The rst one employs a high-resolution scanning fluorescence mapping of a geological sample, and the second one is a coherent x-ray diffraction imaging (CXDI) experiment. CXDI is able to reconstruct the illuminated object from recorded coherent diffraction patterns. In a scanning mode, referred to as ptychography, this method is even able to reconstruct the illumination and the object simultaneously. Especially the reconstructed illumination and the possibility of computed propagation of the wave field along the

  17. Nanofocusing refractive X-ray lenses

    Energy Technology Data Exchange (ETDEWEB)

    Boye, Pit

    2010-02-05

    This thesis is concerned with the optimization and development of the production of nanofocusing refractive X-ray lenses. These optics made of either silicon or diamond are well-suited for high resolution X-ray microscopy. The goal of this work is the design of a reproducible manufacturing process which allows the production of silicon lenses with high precision, high quality and high piece number. Furthermore a process for the production of diamond lenses is to be developed and established. In this work, the theoretical basics of X-rays and their interaction with matter are described. Especially, aspects of synchrotron radiation are emphasized. Important in X-ray microscopy are the different optics. The details, advantages and disadvantages, in particular those of refractive lenses are given. To achieve small X-ray beams well beyond the 100 nm range a small focal length is required. This is achieved in refractive lenses by moving to a compact lens design where several single lenses are stacked behind each other. The, so-called nanofocusing refractive lenses (NFLs) have a parabolic cylindrical shape with lateral structure sizes in the micrometer range. NFLs are produced by using micro-machining techniques. These micro-fabrication processes and technologies are introduced. The results of the optimization and the final fabrication process for silicon lenses are presented. Subsequently, two experiments that are exemplary for the use of NFLs, are introduced. The rst one employs a high-resolution scanning fluorescence mapping of a geological sample, and the second one is a coherent x-ray diffraction imaging (CXDI) experiment. CXDI is able to reconstruct the illuminated object from recorded coherent diffraction patterns. In a scanning mode, referred to as ptychography, this method is even able to reconstruct the illumination and the object simultaneously. Especially the reconstructed illumination and the possibility of computed propagation of the wave field along the

  18. Stress-Detection Lenses

    Science.gov (United States)

    1996-01-01

    An Ames Research Center scientist invented an infrared lens used in sunglasses to filter out ultraviolet rays. This product finds its origins in research for military enemy detection. Through a Space Act Agreement, Optical Sales Corporation introduced the Hawkeye Lenses not only as sunglasses but as plant stress detection lenses. The lenses enhance the stressed part of the leaf, which has less chlorophyll than healthy leaves, through dyes that filter out certain wavelengths of light. Plant stress is visible earlier, at a stage when something can be done to save the plants.

  19. Contact lenses fitting after intracorneal ring segments implantation in keratoconus

    Directory of Open Access Journals (Sweden)

    Luciane Bugmann Moreira

    2013-08-01

    Full Text Available PURPOSE: Evaluate contact lenses fitting after intracorneal ring implantation for keratoconus, its visual acuity and comfort. METHODS: Retrospective study of patients undergoing contact lenses fitting, after intracorneal ring for keratoconus. The criterion for contact lens fitting was unsatisfactory visual acuity with spectacle correction as referred by the patients. All patients were intolerants to contact lenses prior to intracorneal implantation. Visual acuity analysis was done by conversion of Snellen to logMAR scales. The comfort was evaluated according subjective questioning of good, medium or poor comfort. RESULTS: Nineteen patients were included in the study. Two patients (10.5% did not achieved good comfort with contact lenses and underwent penetrating keratoplasties. All the others 17 patients showed good or medium comfort. Four rigid gas-permeable contact lenses were fitted, one piggyback approach, 3 toric soft contact lenses, 2 soft lenses specially design for keratoconus and 7 disposable soft lenses. The average visual acuity improved from 0.77 ± 0.37 to 0.19 ± 0.13 logMAR units after contact lenses fitting. CONCLUSION: Contact lens fitting after intracorneal ring is possible, provides good comfort, improves visual acuity, and therefore, may postpone the need for penetrating keratoplasty.

  20. Weakly oval electron lense

    International Nuclear Information System (INIS)

    Daumenov, T.D.; Alizarovskaya, I.M.; Khizirova, M.A.

    2001-01-01

    The method of the weakly oval electrical field getting generated by the axially-symmetrical field is shown. Such system may be designed with help of the cylindric form coaxial electrodes with the built-in quadrupole duplet. The singularity of the indicated weakly oval lense consists of that it provides the conducting both mechanical and electronic adjustment. Such lense can be useful for elimination of the near-axis astigmatism in the electron-optical system

  1. The Importance of Disclosure: Lesbian, Gay, Bisexual, Transgender/Transsexual, Queer/Questioning, Intersex (LGBTQI) Individuals and the Cancer Continuum

    Science.gov (United States)

    Quinn, Gwendolyn P.; Schabath, Matthew B.; Sanchez, Julian; Sutton, Steven K.; Green, B. Lee

    2015-01-01

    Precis The Lesbian, Gay, Bisexual, Transgender/Transsexual, Queer/Questioning, Intersex (LGBTQI) population experiences cancer health disparities due to lack of disclosure and knowledge about increased cancer risk. Oncology health care providers and institutions should create environments that encourage disclosure of sexual orientation and identity. PMID:25521303

  2. A importância de um questionário de avaliação de unidade curricular

    Directory of Open Access Journals (Sweden)

    Maristela Reis dos Santos

    Full Text Available O objetivo do estudo foi analisar a confiabilidade e validade interna de um questionário de satisfação aplicado prospectivamente a alunos do sexto ano médico que frequentaram o estágio de Neonatologia em uma universidade pública de 2000 a 2011. Responderam ao questionário 1.349 (97,4% alunos. O coeficiente de Cronbach foi 0,7. A análise fatorial determinou quatro domínios: atuação dos docentes, assistência na sala de parto, número de recém-nascidos assistidos e carga teórica, que explicaram, respectivamente, 18%, 16%, 14% e 9% da variância total. O escore de satisfação foi 89,3 ± 7,6% do escore máximo, o número de recém-nascidos recepcionados na sala de parto/aluno foi 4,7 ± 3,3, e as notas do pré-teste e pós-teste foram 5,3 ± 0,9 e 8,8 ± 0,5, respectivamente. A correlação de Pearson entre o escore total e a nota do pós-teste foi 0,7 (p = 0,010 . Houve correlação positiva entre escore de satisfação e qualidade das aulas, aproveitamento na sala de parto, atuação do plantonista e docente, atendimento ao recém-nascido e hospital com condições para o aprendizado. Concluiu-se que a confiabilidade e a validade interna do questionário foram adequadas, e o escore de satisfação do aluno foi elevado.

  3. Phosphorylcholine and phosphorylethanolamine in human and rhesus monkey lenses.

    Science.gov (United States)

    Jernigan, H M; Zigler, J S

    1989-11-01

    Phosphorylcholine (P-choline) and phosphorylethanolamine (P-ethanolamine) are important precursors of phospholipids. The metabolism and concentration of P-choline has been shown to change in animal models of cataract, especially in oxidatively or osmotically stressed rat lenses. The concentrations of P-choline and P-ethanolamine were determined in monkey lenses and in normal and cataractous human lenses, and the rate of synthesis of P-choline was determined in human and monkey lenses. The concentration of P-choline in 53 clear human lenses was 0.94 mM (+/- 0.31 S.D.) and was relatively unaffected by age, eye bank storage, or freezing. There was a 70% decrease in P-choline in brown cataracts but no significant change from normal in non-brown cataracts. The concentration of P-ethanolamine in human lenses was 0.45 mM (+/- 0.26 S.D.), and it appeared to decrease during frozen storage of lenses and in cataracts. The concentrations of P-choline and P-ethanolamine in 12 rhesus monkey lenses were 1.51 mM (+/- 0.27 S.D.) and 0.75 mM (+/- 0.14 S.D.), respectively. The rate of synthesis of P-choline in monkey lenses incubated with [3H]choline was 8 nmol hr-1 g-1 wet weight in 1 mM choline. Adult human lenses incubated in 1 mM choline synthesized P-choline at a rate of 23 nmol hr-1 g-1 (+/- 6 S.D.). This limited capacity for P-choline synthesis in primate lenses may contribute to the lower P-choline concentration relative to rat lenses, which contain 11 mM P-choline and can synthesize P-choline at an apparent maximum rate of 130 nmol hr-1 g-1.

  4. Blog-based applications and health information: two case studies that illustrate important questions for Consumer Health Informatics (CHI) research.

    Science.gov (United States)

    Adams, Samantha A

    2010-06-01

    Weblogs (blogs), together with podcasts and wikis are part of the larger body of next-generation communication applications dubbed "web 2.0." Within the specific area of health care, little attention has been devoted to understanding what applications are available to the lay public and how these are being used. In this study, a literature review on blogs and blogging practices was conducted, followed by case study analyses of two separate sites that use blogging tools to help patients and other lay web end-users record health-related experiences. This paper explores the diverse purposes for which blogging applications can be (or are being) used in relation to health and introduces the idea of "health goal-oriented" blogging. The discussion focuses on relevant informatics questions that arise with respect to the use of blogs and makes suggestions for subsequent research. Copyright 2008 Elsevier Ireland Ltd. All rights reserved.

  5. Weak Weak Lensing : How Accurately Can Small Shears be Measured?

    NARCIS (Netherlands)

    Kuijken, K.

    2006-01-01

    Abstract: Now that weak lensing signals on the order of a percent are actively being searched for (cosmic shear, galaxy-galaxy lensing, large radii in clusters...) it is important to investigate how accurately weak shears can be determined. Many systematic effects are present, and need to be

  6. How To Talk to Teens about Really Important Things: Specific Questions and Answers and Useful Things To Say.

    Science.gov (United States)

    Schaefer, Charles E.; DiGeronimo, Theresa Foy

    For parents of teenagers, talking about sex, drugs, lifestyle choices, AIDS, and divorce can be one of life's toughest challenges. This books serves as a guide for those who have found themselves ill prepared and ill at ease when discussing some of life's most important issues with teens. The book also helps to bridge the gap in parent-teen…

  7. Plasma lenses for focusing relativistic electron beams

    International Nuclear Information System (INIS)

    Govil, R.; Wheeler, S.; Leemans, W.

    1997-01-01

    The next generation of colliders require tightly focused beams with high luminosity. To focus charged particle beams for such applications, a plasma focusing scheme has been proposed. Plasma lenses can be overdense (plasma density, n p much greater than electron beam density, n b ) or underdense (n p less than 2 n b ). In overdense lenses the space-charge force of the electron beam is canceled by the plasma and the remaining magnetic force causes the electron beam to self-pinch. The focusing gradient is nonlinear, resulting in spherical aberrations. In underdense lenses, the self-forces of the electron beam cancel, allowing the plasma ions to focus the beam. Although for a given beam density, a uniform underdense lens produces smaller focusing gradients than an overdense lens, it produces better beam quality since the focusing is done by plasma ions. The underdense lens can be improved by tapering the density of the plasma for optimal focusing. The underdense lens performance can be enhanced further by producing adiabatic plasma lenses to avoid the Oide limit on spot size due to synchrotron radiation by the electron beam. The plasma lens experiment at the Beam Test Facility (BTF) is designed to study the properties of plasma lenses in both overdense and underdense regimes. In particular, important issues such as electron beam matching, time response of the lens, lens aberrations and shot-to-shot reproducibility are being investigated

  8. Biocompatibility of Intraocular Lenses.

    Science.gov (United States)

    Özyol, Pelin; Özyol, Erhan; Karel, Fatih

    2017-08-01

    The performance of an intraocular lens is determined by several factors such as the surgical technique, surgical complications, intraocular lens biomaterial and design, and host reaction to the lens. The factor indicating the biocompatibility of an intraocular lens is the behavior of inflammatory and lens epithelial cells. Hence, the biocompatibility of intraocular lens materials is assessed in terms of uveal biocompatibility, based on the inflammatory foreign-body reaction of the eye against the implant, and in terms of capsular biocompatibility, determined by the relationship of the intraocular lens with residual lens epithelial cells within the capsular bag. Insufficient biocompatibility of intraocular lens materials may result in different clinical entities such as anterior capsule opacification, posterior capsule opacification, and lens epithelial cell ongrowth. Intraocular lenses are increasingly implanted much earlier in life in cases such as refractive lens exchange or pediatric intraocular lens implantation after congenital cataract surgery, and these lenses are expected to exhibit maximum performance for many decades. The materials used in intraocular lens manufacture should, therefore, ensure long-term uveal and capsular biocompatibility. In this article, we review the currently available materials used in the manufacture of intraocular lenses, especially with regard to their uveal and capsular biocompatibility, and discuss efforts to improve the biocompatibility of intraocular lenses.

  9. Photovoltaic and economy. Answers to the 10 most important questions; Photovoltaik und Wirtschaftlichkeit. Antworten auf die 10 wichtigsten Fragen

    Energy Technology Data Exchange (ETDEWEB)

    Vogtmann, Michael [DGS LV Franken e.V., Nuernberg (Germany)

    2016-04-15

    An economic calculation of the planned PV plant is not an easy task due to various influencing factors. In most cases, the date or the year interested in which the plant is operating in the black. However if one wishes, at least roughly to estimate the efficiency of a PV system, so you have to deal with a whole range of factors that determine the profitability sustainably. Here are the 10 most important aspects are explained. [German] Eine Wirtschaftlichkeitsberechnung der geplanten PV-Anlage ist aufgrund verschiedener Einflussfaktoren keine einfache Aufgabe. In den meisten Faellen interessiert der Zeitpunkt bzw. das Jahr, ab dem der Anlagenbetrieb schwarze Zahlen schreibt. Will man allerdings wenigstens grob die Wirtschaftlichkeit einer PV-Anlage abschaetzen, so muss man sich mit einer ganzen Reihe von Faktoren auseinandersetzen, die die Wirtschaftlichkeit nachhaltig bestimmen. Nachstehend werden die 10 wichtigsten Aspekte erlaeutert.

  10. Learning unit: Thin lenses

    Science.gov (United States)

    Nita, L.-S.

    2012-04-01

    Learning unit: Thin lenses "Why objects seen through lenses are sometimes upright and sometimes reversed" Nita Laura Simona National College of Arts and Crafts "Constantin Brancusi", Craiova, Romania 1. GEOMETRIC OPTICS. 13 hours Introduction (models, axioms, principles, conventions) 1. Thin lenses (Types of lenses. Defining elements. Path of light rays through lenses. Image formation. Required physical quantities. Lens formulas). 2. Lens systems (Non-collated lenses. Focalless systems). 3. Human eye (Functioning as an optical system. Sight defects and their corrections). 4. Optical instruments (Characteristics exemplified by a magnifying glass. Paths of light rays through a simplified photo camera. Path of light rays through a classical microscope) (Physics curriculum for the IXth grade/ 2011). This scenario exposes a learning unit based on experimental sequences (defining specific competencies), as a succession of lessons started by noticing a problem whose solution assumes the setup of an experiment under laboratory conditions. Progressive learning of theme objectives are realised with sequential experimental steps. The central cognitive process is the induction or the generalization (development of new knowledge based on observation of examples or counterexamples of the concept to be learnt). Pupil interest in theme objectives is triggered by problem-situations, for example: "In order to better see small objects I need a magnifying glass. But when using a magnifier, small object images are sometimes seen upright and sometimes seen reversed!" Along the way, pupils' reasoning will converge to the idea: "The image of an object through a lens depends on the relative distances among object, lens, and observer". Associated learning model: EXPERIMENT Specific competencies: derived from the experiment model, in agreement with the following learning unit steps I. Evoking - Anticipation: Size of the problem, formulation of hypotheses and planning of experiment. II

  11. Additive manufacturing of tunable lenses

    Science.gov (United States)

    Schlichting, Katja; Novak, Tobias; Heinrich, Andreas

    2017-02-01

    Individual additive manufacturing of optical systems based on 3D Printing offers varied possibilities in design and usage. In addition to the additive manufacturing procedure, the usage of tunable lenses allows further advantages for intelligent optical systems. Our goal is to bring the advantages of additive manufacturing together with the huge potential of tunable lenses. We produced tunable lenses as a bundle without any further processing steps, like polishing. The lenses were designed and directly printed with a 3D Printer as a package. The design contains the membrane as an optical part as well as the mechanical parts of the lens, like the attachments for the sleeves which contain the oil. The dynamic optical lenses were filled with an oil. The focal length of the lenses changes due to a change of the radius of curvature. This change is caused by changing the pressure in the inside of the lens. In addition to that, we designed lenses with special structures to obtain different areas with an individual optical power. We want to discuss the huge potential of this technology for several applications. Further, an appropriate controlling system is needed. Wéll show the possibilities to control and regulate the optical power of the lenses. The lenses could be used for illumination tasks, and in the future, for individual measurement tasks. The main advantage is the individuality and the possibility to create an individual design which completely fulfills the requirements for any specific application.

  12. RHIC electron lenses upgrades

    Energy Technology Data Exchange (ETDEWEB)

    Gu, X. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Altinbas, Z. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Bruno, D. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Binello, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Costanzo, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Drees, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Fischer, W. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Gassner, D. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Hock, J. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Hock, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Harvey, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Luo, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Marusic, A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mi, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mernick, K. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Michnoff, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Miller, T. A. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Pikin, A. I. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Robert-Demolaize, G. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Samms, T. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Shrey, T. C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Schoefer, V. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Tan, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Than, R. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Thieberger, P. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; White, S. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2015-05-03

    In the Relativistic Heavy Ion Collider (RHIC) 100 GeV polarized proton run in 2015, two electron lenses were used to partially compensate for the head-on beam-beam effect for the first time. Here, we describe the design of the current electron lens, detailing the hardware modifications made after the 2014 commissioning run with heavy ions. A new electron gun with 15-mm diameter cathode is characterized. The electron beam transverse profile was measured using a YAG screen and fitted with a Gaussian distribution. During operation, the overlap of the electron and proton beams was achieved using the electron backscattering detector in conjunction with an automated orbit control program.

  13. Traveling questions

    DEFF Research Database (Denmark)

    Hoeyer, Klaus

    2016-01-01

    In this paper, I argue that uncertainty and nonknowledge, and not just research results, can be important vehicles of translation through which genetic research participation comes to affect the lives of research participants. Based on interviews with participants in a genetic research project, I....... Research questions, and not just results, may serve as a generative form of knowledge that can travel as fast as any answer....

  14. Magnetic electron lenses

    CERN Document Server

    1982-01-01

    No single volume has been entirely devoted to the properties of magnetic lenses, so far as I am aware, although of course all the numerous textbooks on electron optics devote space to them. The absence of such a volume, bringing together in­ formation about the theory and practical design of these lenses, is surprising, for their introduction some fifty years ago has created an entirely new family of commercial instruments, ranging from the now traditional transmission electron microscope, through the reflection and transmission scanning microscopes, to co­ lumns for micromachining and microlithography, not to mention the host of experi­ mental devices not available commercially. It therefore seemed useful to prepare an account of the various aspects of mag­ netic lens studies. These divide naturally into the five chapters of this book: the theoretical background, in which the optical behaviour is described and formu­ lae given for the various aberration coefficients; numerical methods for calculat­ ing...

  15. Halo-lensing or Self-lensing? Locating the MACHO Lenses

    Science.gov (United States)

    Nelson, C. A.; Cook, K. H.; Popowski, P.; Drake, A. J.; Marshall, S. L.; Griest, K.; Vandehei, T.; Alcock, C.; Allsman, R. A.; Axelrod, T. S.; Freeman, K. C.; Peterson, B. A.; Alves, D. R.; Becker, A. C.; Stubbs, C. W.; Tomaney, A. B.; Bennett, D. P.; Geha, M.; Lehner, M. J.; Minniti, D.; Pratt, M. R.; Quinn, P. J.; Sutherland, W.; Welch, D.; MACHO Collaboration

    2000-12-01

    There are two principle geometrical arrangements which may explain Large Magellanic Cloud (LMC) microlensing: a) halo-lensing, in which the lensed object is part of the Milky Way galactic halo and b) self-lensing, in which the lensed object is part of the LMC. Self-lensing in turn may be broken into two categories: LMC-LMC self-lensing, in which both the source and the lens reside in the LMC and background self-lensing, in which the lens is a star in the LMC and the source star is drawn from some population behind the LMC. Models suggest the contribution of LMC-LMC self-lensing is small, so the nature of LMC microlensing may be estimated from the location of the microlensing source stars. If the source stars are in the LMC then microlensing is dominated by halo-lensing; conversely if the source stars are located behind the LMC then microlensing is dominated by self-lensing. Since background populations reside behind the LMC, we expect them to be both redder and fainter then the average population of the LMC. We attempt to determine if the MACHO source stars come from such a background population by comparing the HST color-magnitude diagram (CMD) of source stars to the CMD of the average population of the LMC and looking for the effects of extra reddening and extinction. The microlensing source stars are identified by deriving accurate centroids in the ground-based MACHO images using difference image analysis (DIA) and then transforming the DIA coordinates to the HST frame. Preliminary results suggest that halo-lensing accounts for ≳ 40% of the observed microlensing results. Support provided by NASA, DOE, NSF and NPSC.

  16. Adherence of cysts and trophozoites of Acanthamoeba to unworn rigid gas permeable and soft contact lenses.

    Science.gov (United States)

    Sharma, S; Ramachandran, L; Rao, G N

    1995-10-01

    Contact lens related Acanthamoeba keratitis has been more often associated with the use of soft contact lenses than with the use of rigid gas permeable (RGP) contact lenses. We studied the adherence of Acanthamoeba cysts and trophozoites to unworn RGP (silicone acrylate and fluoropolymer) and low and high water content soft contact lenses marketed in India. A human corneal isolate of Acanthamoeba polyphaga suspended in saline (1 x 10(5) amoebae/mL) was used. Lens segments were exposed to A. polyphaga cysts or trophozoites with or without shaking. After exposure for zero to 7 hours, lenses were either washed or not washed and the adherence was determined using light microscopy and a hemocytometer (per square millimeter of the lens). Both cysts and trophozoites immediately adhered to all four types of lenses. Adhesion increased with an increase in exposure time. The number of adherent cysts and trophozoites was higher (P = 0.043-0.0003) in the unwashed group of lenses at all exposure times for all lenses. Among washed groups, adherence was greatest with RGP silicone acrylate and high water content soft lenses. Trophozoites of Acanthamoeba showed greater adherence to RGP lenses, whereas cysts showed greater adherence to high water content soft lenses. Shaking did not have a significant effect on adherence. Adhesion of Acanthamoeba to contact lenses may play an important role in the pathogenesis of Acanthamoeba keratitis.

  17. Subaru Weak Lensing Measurements of Four Strong Lensing Clusters: Are Lensing Clusters Over-Concentrated?

    Energy Technology Data Exchange (ETDEWEB)

    Oguri, Masamune; Hennawi, Joseph F.; Gladders, Michael D.; Dahle, Haakon; Natarajan, Priyamvada; Dalal, Neal; Koester, Benjamin P.; Sharon, Keren; Bayliss, Matthew

    2009-01-29

    We derive radial mass profiles of four strong lensing selected clusters which show prominent giant arcs (Abell 1703, SDSS J1446+3032, SDSS J1531+3414, and SDSS J2111-0115), by combining detailed strong lens modeling with weak lensing shear measured from deep Subaru Suprime-cam images. Weak lensing signals are detected at high significance for all four clusters, whose redshifts range from z = 0.28 to 0.64. We demonstrate that adding strong lensing information with known arc redshifts significantly improves constraints on the mass density profile, compared to those obtained from weak lensing alone. While the mass profiles are well fitted by the universal form predicted in N-body simulations of the {Lambda}-dominated cold dark matter model, all four clusters appear to be slightly more centrally concentrated (the concentration parameters c{sub vir} {approx} 8) than theoretical predictions, even after accounting for the bias toward higher concentrations inherent in lensing selected samples. Our results are consistent with previous studies which similarly detected a concentration excess, and increases the total number of clusters studied with the combined strong and weak lensing technique to ten. Combining our sample with previous work, we find that clusters with larger Einstein radii are more anomalously concentrated. We also present a detailed model of the lensing cluster Abell 1703 with constraints from multiple image families, and find the dark matter inner density profile to be cuspy with the slope consistent with -1, in agreement with expectations.

  18. Pulsar lensing geometry

    Science.gov (United States)

    Liu, Siqi; Pen, Ue-Li; Macquart, J.-P.; Brisken, Walter; Deller, Adam

    2016-05-01

    We test the inclined sheet pulsar scintillation model (Pen & Levin) against archival very long baseline interferometry (VLBI) data on PSR 0834+06 and show that its scintillation properties can be precisely reproduced by a model in which refraction occurs on two distinct lens planes. These data strongly favour a model in which grazing-incidence refraction instead of diffraction off turbulent structures is the primary source of pulsar scattering. This model can reproduce the parameters of the observed diffractive scintillation with an accuracy at the percent level. Comparison with new VLBI proper motion results in a direct measure of the ionized interstellar medium (ISM) screen transverse velocity. The results are consistent with ISM velocities local to the PSR 0834+06 sight-line (through the Galaxy). The simple 1-D structure of the lenses opens up the possibility of using interstellar lenses as precision probes for pulsar lens mapping, precision transverse motions in the ISM, and new opportunities for removing scattering to improve pulsar timing. We describe the parameters and observables of this double screen system. While relative screen distances can in principle be accurately determined, a global conformal distance degeneracy exists that allows a rescaling of the absolute distance scale. For PSR B0834+06, we present VLBI astrometry results that provide (for the first time) a direct measurement of the distance of the pulsar. For most of the recycled millisecond pulsars that are the targets of precision timing observations, the targets where independent distance measurements are not available. The degeneracy presented in the lens modelling could be broken if the pulsar resides in a binary system.

  19. The epidemiology of microbial keratitis with silicone hydrogel contact lenses.

    Science.gov (United States)

    Stapleton, Fiona; Keay, Lisa; Edwards, Katie; Holden, Brien

    2013-01-01

    It was widely anticipated that after the introduction of silicone hydrogel lenses, the risk of microbial keratitis would be lower than with hydrogel lenses because of the reduction in hypoxic effects on the corneal epithelium. Large-scale epidemiological studies have confirmed that the absolute and relative risk of microbial keratitis is unchanged with overnight use of silicone hydrogel materials. The key findings include the following: (1) The risk of infection with 30 nights of silicone hydrogel use is equivalent to 6 nights of hydrogel extended wear; (2) Occasional overnight lens use is associated with a greater risk than daily lens use; (3) The rate of vision loss due to corneal infection with silicone hydrogel contact lenses is similar to that seen in hydrogel lenses; (4) The spectrum of causative organisms is similar to that seen in hydrogel lenses, and the material type does not impact the corneal location of presumed microbial keratitis; and (5) Modifiable risk factors for infection include overnight lens use, the degree of exposure, failing to wash hands before lens handling, and storage case hygiene practice. The lack of change in the absolute risk of disease would suggest that exposure to large number of pathogenic organisms can overcome any advantages obtained from eliminating the hypoxic effects of contact lenses. Epidemiological studies remain important in the assessment of new materials and modalities. Consideration of an early adopter effect with studies involving new materials and modalities and further investigation of the impact of second-generation silicone hydrogel materials is warranted.

  20. Fitting gravitational lenses: truth or delusion

    Science.gov (United States)

    Evans, N. Wyn; Witt, Hans J.

    2003-11-01

    The observables in a strong gravitational lens are usually just the image positions and sometimes the flux ratios. We develop a new and simple algorithm which allows a set of models to be fitted exactly to the observations. Taking our cue from the strong body of evidence that early-type galaxies are close to isothermal, we assume that the lens is scale-free with a flat rotation curve. External shear can be easily included. Our algorithm allows full flexibility regarding the angular structure of the lensing potential. Importantly, all the free parameters enter linearly into the model and so the lens and flux ratio equations can always be solved by straightforward matrix inversion. The models are only restricted by the fact that the surface mass density must be positive. We use this new algorithm to examine some of the claims made for anomalous flux ratios. It has been argued that such anomalies betray the presence of substantial amounts of substructure in the lensing galaxy. We demonstrate by explicit construction that some of the lens systems for which substructure has been claimed can be well fitted by smooth lens models. This is especially the case when the systematic errors in the flux ratios (caused by microlensing or differential extinction) are taken into account. However, there is certainly one system (B1422+231) for which the existing smooth models are definitely inadequate and for which substructure may be implicated. Within a few tens of kpc of the lensing galaxy centre, dynamical friction and tidal disruption are known to be very efficient at dissolving any substructure. Very little substructure is projected within the Einstein radius. The numbers of strong lenses for which substructure is currently being claimed may be so large that this contradicts rather than supports cold dark matter theories.

  1. Cosmology with weak lensing surveys

    International Nuclear Information System (INIS)

    Munshi, Dipak; Valageas, Patrick; Waerbeke, Ludovic van; Heavens, Alan

    2008-01-01

    Weak gravitational lensing is responsible for the shearing and magnification of the images of high-redshift sources due to the presence of intervening matter. The distortions are due to fluctuations in the gravitational potential, and are directly related to the distribution of matter and to the geometry and dynamics of the Universe. As a consequence, weak gravitational lensing offers unique possibilities for probing the Dark Matter and Dark Energy in the Universe. In this review, we summarise the theoretical and observational state of the subject, focussing on the statistical aspects of weak lensing, and consider the prospects for weak lensing surveys in the future. Weak gravitational lensing surveys are complementary to both galaxy surveys and cosmic microwave background (CMB) observations as they probe the unbiased non-linear matter power spectrum at modest redshifts. Most of the cosmological parameters are accurately estimated from CMB and large-scale galaxy surveys, so the focus of attention is shifting to understanding the nature of Dark Matter and Dark Energy. On the theoretical side, recent advances in the use of 3D information of the sources from photometric redshifts promise greater statistical power, and these are further enhanced by the use of statistics beyond two-point quantities such as the power spectrum. The use of 3D information also alleviates difficulties arising from physical effects such as the intrinsic alignment of galaxies, which can mimic weak lensing to some extent. On the observational side, in the next few years weak lensing surveys such as CFHTLS, VST-KIDS and Pan-STARRS, and the planned Dark Energy Survey, will provide the first weak lensing surveys covering very large sky areas and depth. In the long run even more ambitious programmes such as DUNE, the Supernova Anisotropy Probe (SNAP) and Large-aperture Synoptic Survey Telescope (LSST) are planned. Weak lensing of diffuse components such as the CMB and 21 cm emission can also

  2. Use of Scleral Lenses and Miniscleral Lenses After Penetrating Keratoplasty.

    Science.gov (United States)

    Barnett, Melissa; Lien, Vivian; Li, Jennifer Y; Durbin-Johnson, Blythe; Mannis, Mark J

    2016-05-01

    To examine the clinical outcomes of scleral lenses for visual rehabilitation after penetrating keratoplasty (PK). A retrospective review was conducted for 34 patients (48 eyes) who had a history of prior PK and were fit with scleral lenses between October 2009 and December 2013 at the UC Davis Eye Center. The most common initial indication for PK was keratoconus in 27 eyes (56%). Thirty-three eyes (69%) had previously been fit with other types of contact lenses, with small-diameter rigid gas-permeable lenses being the most common. The improvement in best-corrected visual acuity with a scleral lens compared with prior spectacle refraction or other contact lens was a mean of two best-corrected visual acuity lines. Forty-four eyes (91.7%) achieved functional vision with best scleral lens-corrected visual acuities of 20/40 or better. Patients who continued wearing scleral lenses were significantly more likely to report "good" subjective vision compared with patients who abandoned scleral lens wear (P=0.009), although change in objective best-corrected visual acuity did not differ significantly. There were no cases of infectious keratitis. Six eyes (12.5%) developed graft rejection; 3 were able to resume scleral lens wear. Nineteen eyes (39.5%) discontinued scleral lens wear for various reasons, the most common reason for discontinuation of lens wear was difficulty with scleral lens insertion or removal (8 eyes, 42.1%). Scleral lenses are effective and safe in patients who have had PK. There was a mean gain in visual acuity, with the majority of patients achieving 20/40 vision or better. The patient's subjective perception of vision was a significant factor in determining whether scleral lens wear was continued or abandoned.

  3. Scleral lenses: a literature review.

    Science.gov (United States)

    Schornack, Muriel M

    2015-01-01

    To present a comprehensive review of current and historical literature on scleral lenses. A comprehensive search of several databases from each database's earliest inception to May 23, 2014 was conducted by an experienced librarian with input from the author to locate articles related to scleral lens design, fabrication, prescription, and management. A total of 899 references were identified, 184 of which were directly related to scleral lenses. References of interest were organized by date, topic, and study design. Most of articles published before 1983 presented lens design and fabrication techniques or indications for scleral lens therapy. Case reviews published after 1983 identified major indications for scleral lenses (corneal ectasia, ocular surface disease, and refractive error) and visual and functional outcomes of scleral lens wear. Statistically significant improvements in visual acuity, vision-related quality of life, and ocular surface integrity were reported. Reviews of ocular and systemic conditions suggested that comprehensive management strategies for these conditions could include scleral lenses. Early work investigating scleral lens fitting characteristics, optical qualities, and potential physiological impact on anterior ocular structures have been published in the past 5 years. Indications for scleral lens wear are well-established. Developing areas of research on the physiologic impact of scleral lens wear on the ocular surface, the use of technology to improve scleral lens vision and fit, and the impact of these devices on the quality of life should further enhance our understanding of scleral lenses in the future.

  4. Asking Questions in Academia

    DEFF Research Database (Denmark)

    Hansen, Annette Skovsted

    2014-01-01

    Motivation for the activity In academia the most important skill is to ask academically relevant and sound questions. This is not easy and students need to practice asking questions orally and in writing before they write research papers.......Motivation for the activity In academia the most important skill is to ask academically relevant and sound questions. This is not easy and students need to practice asking questions orally and in writing before they write research papers....

  5. The theory of stochastic cosmological lensing

    Energy Technology Data Exchange (ETDEWEB)

    Fleury, Pierre; Uzan, Jean-Philippe [Institut d' Astrophysique de Paris, UMR 7095 du CNRS, 98 bis Bd Arago, 75014 Paris (France); Larena, Julien, E-mail: fleury@iap.fr, E-mail: j.larena@ru.ac.za, E-mail: uzan@iap.fr [Department of Mathematics, Rhodes University, Grahamstown 6140 (South Africa)

    2015-11-01

    On the scale of the light beams subtended by small sources, e.g. supernovae, matter cannot be accurately described as a fluid, which questions the applicability of standard cosmic lensing to those cases. In this article, we propose a new formalism to deal with small-scale lensing as a diffusion process: the Sachs and Jacobi equations governing the propagation of narrow light beams are treated as Langevin equations. We derive the associated Fokker-Planck-Kolmogorov equations, and use them to deduce general analytical results on the mean and dispersion of the angular distance. This formalism is applied to random Einstein-Straus Swiss-cheese models, allowing us to: (1) show an explicit example of the involved calculations; (2) check the validity of the method against both ray-tracing simulations and direct numerical integration of the Langevin equation. As a byproduct, we obtain a post-Kantowski-Dyer-Roeder approximation, accounting for the effect of tidal distortions on the angular distance, in excellent agreement with numerical results. Besides, the dispersion of the angular distance is correctly reproduced in some regimes.

  6. Objective and subjective performance of scleral lenses and new advances in scleral lens technologies

    NARCIS (Netherlands)

    Visser, E.S.

    2015-01-01

    Scleral lenses are widely recognized for their ability to markedly improve quality of life and giving back patients their ability to perform daily activities, mainly as a result of restoring visual function and/or reduction of ocular discomfort and pain.Scleral lenses are an important front-line

  7. Aspheric lenses for terahertz imaging.

    Science.gov (United States)

    Lo, Yat Hei; Leonhardt, Rainer

    2008-09-29

    We present novel designs for aspheric lenses used in terahertz (THz) imaging. As different surfaces result in different beam shaping properties and in different losses from reflection and absorption, the resultant imaging resolution (i.e. the focal spot size) depends critically on the design approach. We evaluate the different lens designs using Kirchhoff's scalar diffraction theory, and test the predictions experimentally. We also show that our lenses can achieve sub-wavelength resolution. While our lens designs are tested with THz radiation, the design considerations are applicable also to other regions of the electro-magnetic spectrum.

  8. Gravitational lensing by exotic objects

    Science.gov (United States)

    Asada, Hideki

    2017-11-01

    This paper reviews a phenomenological approach to the gravitational lensing by exotic objects such as the Ellis wormhole lens, where the exotic lens objects may follow a non-standard form of the equation of state or may obey a modified gravity theory. A gravitational lens model is proposed in the inverse powers of the distance, such that the Schwarzschild lens and exotic lenses can be described in a unified manner as a one parameter family. As observational implications, the magnification, shear, photo-centroid motion and time delay in this lens model are discussed.

  9. A questioning environment for scaffolding learners' questioning ...

    African Journals Online (AJOL)

    Given that questioning is one of the most important learning-teaching tools available to both learner and educator, we have created a computer-based scaffolding environment in which students are required to generate questions to interrogate academic texts. Learners have been using this new scaffolding tool this year, and ...

  10. Gravitational Lensing of Supernova Neutrinos

    Energy Technology Data Exchange (ETDEWEB)

    Mena, Olga; /Fermilab /Rome U.; Mocioiu, Irina; /Penn State U.; Quigg, Chris; /Fermilab

    2006-10-01

    The black hole at the center of the galaxy is a powerful lens for supernova neutrinos. In the very special circumstance of a supernova near the extended line of sight from Earth to the galactic center, lensing could dramatically enhance the neutrino flux at Earth and stretch the neutrino pulse.

  11. The Optical Gravitational Lensing Experiment

    Science.gov (United States)

    Udalski, A.; Szymanski, M.; Kaluzny, J.; Kubiak, M.; Mateo, Mario

    1992-01-01

    The technical features are described of the Optical Gravitational Lensing Experiment, which aims to detect a statistically significant number of microlensing events toward the Galactic bulge. Clusters of galaxies observed during the 1992 season are listed and discussed and the reduction methods are described. Future plans are addressed.

  12. Scientific visualization of gravitational lenses

    International Nuclear Information System (INIS)

    Magallon, M.

    1999-01-01

    Concepts related to gravitational lenses are discussed and applied to develop an interactive visualization tool that allow us to investigate them. Optimization strategies were performed to elaborate the tool. Some results obtained from the application of the tool are shown [es

  13. Optics Demonstrations Using Cylindrical Lenses

    Science.gov (United States)

    Ivanov, Dragia; Nikolov, Stefan

    2015-01-01

    In this paper we consider the main properties of cylindrical lenses and propose several demonstrational experiments that can be performed with them. Specifically we use simple glasses full of water to demonstrate some basic geometrical optics principles and phenomena. We also present some less standard experiments that can be performed with such…

  14. Polarization optics of GRIN lenses

    Science.gov (United States)

    Camacho, Javier; Tentori, Diana

    2001-01-01

    In this paper we show that the matrix representation for a linear retarder, given by Jones calculus, can be successfully applied to describe the birefringence properties of GRIN lenses for meridional rays. The usefulness of this description is experimentally verified by comparing the output pattern of a GRIN lens obtained in a linear polariscope with the predicted conoscopic pattern.

  15. Weak lensing and dark energy

    International Nuclear Information System (INIS)

    Huterer, Dragan

    2002-01-01

    We study the power of upcoming weak lensing surveys to probe dark energy. Dark energy modifies the distance-redshift relation as well as the matter power spectrum, both of which affect the weak lensing convergence power spectrum. Some dark-energy models predict additional clustering on very large scales, but this probably cannot be detected by weak lensing alone due to cosmic variance. With reasonable prior information on other cosmological parameters, we find that a survey covering 1000 sq deg down to a limiting magnitude of R=27 can impose constraints comparable to those expected from upcoming type Ia supernova and number-count surveys. This result, however, is contingent on the control of both observational and theoretical systematics. Concentrating on the latter, we find that the nonlinear power spectrum of matter perturbations and the redshift distribution of source galaxies both need to be determined accurately in order for weak lensing to achieve its full potential. Finally, we discuss the sensitivity of the three-point statistics to dark energy

  16. Flat liquid crystal diffractive lenses with variable focus and magnification

    Science.gov (United States)

    Valley, Pouria

    Non-mechanical variable lenses are important for creating compact imaging devices. Various methods employing dielectrically actuated lenses, membrane lenses, and liquid crystal lenses were previously proposed [1-4]. In This dissertation the design, fabrication, and characterization of innovative flat tunable-focus liquid crystal diffractive lenses (LCDL) are presented. LCDL employ binary Fresnel zone electrodes fabricated on Indium-Tin-Oxide using conventional micro-photolithography. The light phase can be adjusted by varying the effective refractive index of a nematic liquid crystal sandwiched between the electrodes and a reference substrate. Using a proper voltage distribution across various electrodes the focal length can be changed between several discrete values. Electrodes are shunted such that the correct phase retardation step sequence is achieved. If the number of 2pi zone boundaries is increased by a factor of m the focal length is changed from f to f/m based on the digitized Fresnel zone equation: f = rm2/2mlambda, where r m is mth zone radius, and lambda is the wavelength. The chromatic aberration of the diffractive lens is addressed and corrected by adding a variable fluidic lens. These LCDL operate at very low voltage levels (+/-2.5V ac input), exhibit fast switching times (20-150 ms), can have large apertures (>10 mm), and small form factor, and are robust and insensitive to vibrations, gravity, and capillary effects that limit membrane and dielectrically actuated lenses. Several tests were performed on the LCDL including diffraction efficiency measurement, switching dynamics, and hybrid imaging with a refractive lens. Negative focal lengths are achieved by adjusting the voltages across electrodes. Using these lenses in combination, magnification can be changed and zoom lenses can be formed. These characteristics make LCDL a good candidate for a variety of applications including auto-focus and zoom lenses in compact imaging devices such as camera

  17. The cuticular nature of corneal lenses in Drosophila melanogaster.

    Science.gov (United States)

    Stahl, Aaron L; Charlton-Perkins, Mark; Buschbeck, Elke K; Cook, Tiffany A

    2017-07-01

    The dioptric visual system relies on precisely focusing lenses that project light onto a neural retina. While the proteins that constitute the lenses of many vertebrates are relatively well characterized, less is known about the proteins that constitute invertebrate lenses, especially the lens facets in insect compound eyes. To address this question, we used mass spectrophotometry to define the major proteins that comprise the corneal lenses from the adult Drosophila melanogaster compound eye. This led to the identification of four cuticular proteins: two previously identified lens proteins, drosocrystallin and retinin, and two newly identified proteins, Cpr66D and Cpr72Ec. To determine which ommatidial cells contribute each of these proteins to the lens, we conducted in situ hybridization at 50% pupal development, a key age for lens secretion. Our results confirm previous reports that drosocrystallin and retinin are expressed in the two primary corneagenous cells-cone cells and primary pigment cells. Cpr72Ec and Cpr66D, on the other hand, are more highly expressed in higher order interommatidial pigment cells. These data suggest that the complementary expression of cuticular proteins give rise to the center vs periphery of the corneal lens facet, possibly facilitating a refractive gradient that is known to reduce spherical aberration. Moreover, these studies provide a framework for future studies aimed at understanding the cuticular basis of corneal lens function in holometabolous insect eyes.

  18. Contact Lenses for Keratoconus- Current Practice

    Science.gov (United States)

    Moschos, Marilita M.; Nitoda, Eirini; Georgoudis, Panagiotis; Balidis, Miltos; Karageorgiadis, Eleftherios; Kozeis, Nikos

    2017-01-01

    Background: Keratoconus is a chronic, bilateral, usuallly asymmetrical, non-inflammatory, ectatic disorder, being characterized by progressive steepening, thinning and apical scarring of the cornea. Initially, the patient is asymptomatic, but the visual acuity gradually decreases, resulting in significant vision loss due to the development of irregular astigmatism, myopia, corneal thinning and scarring. The classic treatment of visual rehabilitation in keratoconus is based on spectacles and contact lenses (CLs). Objective: To summarize the types of CLs used in the treatment of keratoconus. This is literature review of several important published articles focusing on the visual rehabilitation in keratoconus with CLs. Method: Gas permeable (GP) CLs have been found to achieve better best corrected visual acuity than spectacles, eliminating 3rd-order coma root-mean-square (RMS) error, 3rd-order RMS, and higher-order RMS. However, they have implicated in reduction of corneal basal epithelial cell and anterior stromal keratocyte densities. Soft CLs seem to provide greater comfort and lower cost, but the low oxygen permeability (if the lens is not a silicone hydrogel), and the inability to mask moderate to severe irregular astigmatism are the main disadvantages of them. On the other hand, scleral CLs ensure stable platforms, which eliminate high-order aberrations and provide good centration and visual acuity. Their main disadvantages include the difficulties in application and removal of these lenses along with corneal flattening and swelling. Result: The modern hybrid CLs are indicated in cases of poor centration, poor stability or intolerance with GP lenses. Finally, piggyback CL systems effectively ameliorate visual acuity, but they have been related to corneal neovascularization and giant papillary conjunctivitis. Conclusion: CLs seem to rehabilitate visual performance, diminishing the power of the cylinder and the high-order aberrations. The final choice of CLs is

  19. Legacy question

    International Nuclear Information System (INIS)

    Healy, J.W.

    1977-01-01

    The legacy question discussed refers to the definition of appropriate actions in this generation to provide a world that will allow future generations to use the earth without excessive limitations caused by our use and disposal of potentially hazardous materials

  20. Gravitational lensing by rotating wormholes

    Science.gov (United States)

    Jusufi, Kimet; Ã-vgün, Ali

    2018-01-01

    In this paper the deflection angle of light by a rotating Teo wormhole spacetime is calculated in the weak limit approximation. We mainly focus on the weak deflection angle by revealing the gravitational lensing as a partially global topological effect. We apply the Gauss-Bonnet theorem (GBT) to the optical geometry osculating the Teo-Randers wormhole optical geometry to calculate the deflection angle. Furthermore we find the same result using the standard geodesic method. We have found that the deflection angle can be written as a sum of two terms, namely the first term is proportional to the throat of the wormhole and depends entirely on the geometry, while the second term is proportional to the spin angular momentum parameter of the wormhole. A direct observation using lensing can shed light and potentially test the nature of rotating wormholes by comparing with the black holes systems.

  1. A system of catoptric lenses

    International Nuclear Information System (INIS)

    McFarland, P.J.; Rambauske, W.R.

    1973-01-01

    Description is given of a system of catoptric lenses for combining energies provided by a certain number of sources, e.g. optical energies provided by a certain number of lasers. This system comprises sets of mirrors the reflecting surfaces of which have their focuses spaced from a common axis. The mirrors of all these sets are arranged on a common frame, which makes aperture-locking impossible. This can be applied to thermonuclear fusion [fr

  2. Thousand Questions

    DEFF Research Database (Denmark)

    2012-01-01

    (perhaps as an expanded Turing test) on its listeners. These questions are extracted in real-time from Twitter with the keyword search of the ‘?’ symbol to create a spatio-temporal experience. The computerized voice the audience hears is a collective one, an entanglement of humans and non...

  3. Cross-correlation of gravitational lensing from DES Science Verification data with SPT and Planck lensing

    Energy Technology Data Exchange (ETDEWEB)

    Kirk, D.; Omori, Y.; Benoit-Lévy, A.; Cawthon, R.; Chang, C.; Larsen, P.; Amara, A.; Bacon, D.; Crawford, T. M.; Dodelson, S.; Fosalba, P.; Giannantonio, T.; Holder, G.; Jain, B.; Kacprzak, T.; Lahav, O.; MacCrann, N.; Nicola, A.; Refregier, A.; Sheldon, E.; Story, K. T.; Troxel, M. A.; Vieira, J. D.; Vikram, V.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Becker, M. R.; Benson, B. A.; Bernstein, G. M.; Bernstein, R. A.; Bleem, L. E.; Bonnett, C.; Bridle, S. L.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carlstrom, J. E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D' Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D. J.; Jarvis, M.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lima, M.; March, M.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Nichol, R. C.; Ogando, R.; Plazas, A. A.; Reichardt, C. L.; Roodman, A.; Rozo, E.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Simard, G.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Wechsler, R. H.; Weller, J.

    2016-03-10

    We measure the cross-correlation between weak lensing of galaxy images and of the cosmic microwave background (CMB). The effects of gravitational lensing on different sources will be correlated if the lensing is caused by the same mass fluctuations. We use galaxy shape measurements from 139 deg(2) of the Dark Energy Survey (DES) Science Verification data and overlapping CMB lensing from the South Pole Telescope (SPT) and Planck. The DES source galaxies have a median redshift of z(med) similar to 0.7, while the CMB lensing kernel is broad and peaks at z similar to 2. The resulting cross-correlation is maximally sensitive to mass fluctuations at z similar to 0.44. Assuming the Planck 2015 best-fitting cosmology, the amplitude of the DESxSPT cross-power is found to be A(SPT) = 0.88 +/- 0.30 and that from DESxPlanck to be A(Planck) = 0.86 +/- 0.39, where A = 1 corresponds to the theoretical prediction. These are consistent with the expected signal and correspond to significances of 2.9 sigma and 2.2 sigma, respectively. We demonstrate that our results are robust to a number of important systematic effects including the shear measurement method, estimator choice, photo-z uncertainty and CMB lensing systematics. We calculate a value of A = 1.08 +/- 0.36 for DESxSPT when we correct the observations with a simple intrinsic alignment model. With three measurements of this cross-correlation now existing in the literature, there is not yet reliable evidence for any deviation from the expected LCDM level of cross-correlation. We provide forecasts for the expected signal-to-noise ratio of the combination of the five-year DES survey and SPT-3G.

  4. 30 CFR 18.30 - Windows and lenses.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Windows and lenses. 18.30 Section 18.30 Mineral... § 18.30 Windows and lenses. (a) MSHA may waive testing of materials for windows or lenses except headlight lenses. When tested, material for windows or lenses shall meet the test requirements prescribed in...

  5. Planck 2015 results. XV. Gravitational lensing

    CERN Document Server

    Ade, P.A.R.; Arnaud, M.; Ashdown, M.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Bartolo, N.; Basak, S.; Battaner, E.; Benabed, K.; Benoît, A.; Benoit-Lévy, A.; Bernard, J.-P.; Bersanelli, M.; Bielewicz, P.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Boulanger, F.; Bucher, M.; Burigana, C.; Butler, R.C.; Calabrese, E.; Cardoso, J.-F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Combet, C.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Désert, F.-X.; Diego, J.M.; Dole, H.; Donzelli, S.; Doré, O.; Douspis, M.; Ducout, A.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Elsner, F.; Enßlin, T.A.; Eriksen, H.K.; Fergusson, J.; Finelli, F.; Forni, O.; Frailis, M.; Fraisse, A.A.; Franceschi, E.; Frejsel, A.; Galeotta, S.; Galli, S.; Ganga, K.; Giard, M.; Giraud-Héraud, Y.; Gjerløw, E.; González-Nuevo, J.; Górski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.L.; Henrot-Versillé, S.; Hernández-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Hurier, G.; Jaffe, A.H.; Jaffe, T.R.; Jones, W.C.; Juvela, M.; Keihänen, E.; Keskitalo, R.; Kisner, T.S.; Kneissl, R.; Knoche, J.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lähteenmäki, A.; Lamarre, J.-M.; Lasenby, A.; Lattanzi, M.; Lawrence, C.R.; Leonardi, R.; Lesgourgues, J.; Levrier, F.; Lewis, A.; Liguori, M.; Lilje, P.B.; Linden-Vørnle, M.; López-Caniego, M.; Lubin, P.M.; Macías-Pérez, J.F.; Maggio, G.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Martin, P.G.; Martínez-González, E.; Masi, S.; Matarrese, S.; McGehee, P.; Meinhold, P.R.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschênes, M.-A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Murphy, J.A.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Nørgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Pettorino, V.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Popa, L.; Pratt, G.W.; Prézeau, G.; Prunet, S.; Puget, J.-L.; Rachen, J.P.; Reach, W.T.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Renzi, A.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Rossetti, M.; Roudier, G.; Rowan-Robinson, M.; Rubiño-Martín, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savelainen, M.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Spencer, L.D.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sutton, D.; Suur-Uski, A.-S.; Sygnet, J.-F.; Tauber, J.A.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Wade, L.A.; Wandelt, B.D.; Wehus, I.K.; White, M.; Yvon, D.; Zacchei, A.

    2016-01-01

    We present the most significant measurement of the cosmic microwave background (CMB) lensing potential to date (at a level of 40 sigma), using temperature and polarization data from the Planck 2015 full-mission release. Using a polarization-only estimator we detect lensing at a significance of 5 sigma. We cross-check the accuracy of our measurement using the wide frequency coverage and complementarity of the temperature and polarization measurements. Public products based on this measurement include an estimate of the lensing potential over approximately 70% of the sky, an estimate of the lensing potential power spectrum in bandpowers for the multipole range 40lensing potential power spectrum and that found in the best-fitting LCDM model based on the Planck temperature and polarization power spectra. Using the lensing likelihood alone we obtain a percent-level measurement of ...

  6. Scleral lenses in the management of keratoconus.

    Science.gov (United States)

    Schornack, Muriel M; Patel, Sanjay V

    2010-01-01

    To describe the use of Jupiter scleral lenses (Medlens Innovations, Front Royal, VA; and Essilor Contact Lenses, Inc., Dallas, TX) in the management of keratoconus. We performed a single-center retrospective chart review of our initial 32 patients with keratoconus evaluated for scleral lens wear. All patients were referred for scleral lens evaluation after exhausting other nonsurgical options for visual correction. Diagnostic lenses were used in the initial fitting process. If adequate fit could not be achieved with standard lenses, custom lenses were designed in consultation with the manufacturers' specialists. The following measures were evaluated for each patient: ability to tolerate and handle lenses, visual acuity with scleral lenses, number of lenses, and visits needed to complete the fitting process. Fifty-two eyes of 32 patients were evaluated for scleral lens wear. Of these, 12 patients (20 eyes) decided not to pursue scleral lens wear after initial evaluation. One patient (2 eyes) abandoned the fitting process after cataract surgery. The remaining 19 patients (30 eyes) were fit successfully. The average number of lenses ordered per eye was 1.5. The fitting process required an average of 2.8 visits. Standard lenses were prescribed for 23 eyes, and custom designs were needed for 7 eyes. Median best-corrected visual acuity improved from 20/40 (mean, 20/76) before scleral lens fitting to 20/20 (mean, 20/30) after fitting. Follow-up ranged from 3 to 32 months. Jupiter scleral lenses provide acceptable visual acuity and comfort in patients with keratoconus. The availability of diagnostic lenses facilitates the fitting process.

  7. Une question

    OpenAIRE

    Resweber, Jean-Paul

    2005-01-01

    Dans deux conférences consacrées à une analyse critique du discours de Freud, L. Althusser, pose, semble-t-il, la bonne question , quoique d’une manière quelque peu embarrassée et péremptoire. Le rapport de Freud à la philosophie, qu’il soit examiné au travers d’une confrontation problématique entre celle-ci et psychanalyse naissante, ou bien au travers d’un dialogue entre les postulats nouveaux et les thèses classiques défendues par Platon, Kant, Nietzsche, Schopenhauer ou Wittgenstein, ne s...

  8. Machinery Question

    OpenAIRE

    Meacci, Ferdinando

    2008-01-01

    The “machinery question” was developed by the economist David Ricardo (1772–1823) in the chapter “On Machinery” added to the third edition of his Principles of Political Economy and Taxation (1821). This question related, in his words, to the “influence of machinery on the interests of the different classes of society” and particularly to the “opinion entertained by the labouring class, that the employment of machinery is frequently detrimental to their interests”. Ricardo’s argument was pres...

  9. Braneworld Black Hole Gravitational Lensing

    International Nuclear Information System (INIS)

    Liang Jun

    2017-01-01

    A class of braneworld black holes, which I called as Bronnikov–Melnikov–Dehen (BMD) black holes, are studied as gravitational lenses. I obtain the deflection angle in the strong deflection limit, and further calculate the angular positions and magnifications of relativistic images as well as the time delay between different relativistic images. I also compare the results with those obtained for Schwarzschild and two braneworld black holes, i.e., the tidal Reissner-Nordström (R-N) and the Casadio–Fabbri–Mazzacurati (CFM) black holes. (paper)

  10. The Scales of Gravitational Lensing

    Directory of Open Access Journals (Sweden)

    Francesco De Paolis

    2016-03-01

    Full Text Available After exactly a century since the formulation of the general theory of relativity, the phenomenon of gravitational lensing is still an extremely powerful method for investigating in astrophysics and cosmology. Indeed, it is adopted to study the distribution of the stellar component in the Milky Way, to study dark matter and dark energy on very large scales and even to discover exoplanets. Moreover, thanks to technological developments, it will allow the measure of the physical parameters (mass, angular momentum and electric charge of supermassive black holes in the center of ours and nearby galaxies.

  11. The Origin of Gravitational Lensing: A Postscript to Einstein's 1936 Science Paper

    Science.gov (United States)

    Renn; Sauer; Stachel

    1997-01-10

    Gravitational lensing, now taken as an important astrophysical consequence of the general theory of relativity, was found even before this theory was formulated but was discarded as a speculative idea without any chance of empirical confirmation. Reconstruction of some of Einstein's research notes dating back to 1912 reveals that he explored the possibility of gravitational lensing 3 years before completing his general theory of relativity. On the basis of preliminary insights into this theory, Einstein had already derived the basic features of the lensing effect. When he finally published the very same results 24 years later, it was only in response to prodding by an amateur scientist.

  12. The kinematical structure of gravitationally lensed arcs

    NARCIS (Netherlands)

    Moller, O; Noordermeer, E

    2006-01-01

    In this paper, the expected properties of the velocity fields of strongly lensed arcs behind galaxy clusters are investigated. The velocity profile along typical lensed arcs is determined by ray-tracing light rays from a model source galaxy through parametric cluster toy models consisting of

  13. Modern scleral lenses part I: clinical features.

    NARCIS (Netherlands)

    Visser, E.S.; Visser, R.; Lier, H.J.J. van; Otten, H.M.

    2007-01-01

    PURPOSE: To evaluate the indications for modern scleral lenses and their clinical performance in patients who were fitted with scleral lenses at the authors' practices. METHODS: In this cross-sectional survey, all the necessary data were obtained at the first follow-up visit during the 5-month study

  14. Soft Lenses | Kuming | South African Medical Journal

    African Journals Online (AJOL)

    A series of cases fitted with Bionite soft lenses is described. Good results were obtained in bullous keratopathy, dry eyes, early and moderately advanced Stevens-Johnson syndrome and pemphigoid, and some cases of indolent corneal ulcers. The lenses appear to be a most effective replacement for tarsorrhaphy, haptic ...

  15. Investigating the shelf life of disposable soft contact lenses

    Directory of Open Access Journals (Sweden)

    E. Chetty

    2008-12-01

    Full Text Available Numerous studies have been done to scrutinize the sterility and/or efficacy of contact lens solutions1-3, contact lens storage cases4-6 and soft contact lenses (SCLs 7-10. To the best of our knowledge, a paucity of research regarding the sterility or efficacy of expired SCLs that are in sealed packages exists. One may question the need to investigate this facet of contact lens research. Many blogs and Q&A websites, such as the Optiboard website11, feature contact lens practitioners or contact lens patients who are curious about the repercussions of using expired SCLs. The purpose of this pilot study is not to offer all the answers regarding expired contact lenses, but rather to initiate curiosity about the quality and utility of expired SCLs. This study endeavors to investigate the sterility of sealed SCLs that are past their expiry date. Fifty-four SCLs were tested for the presence of fungal (27 samples and bacterial (27 samples contamination. These samples included both expired and unexpired SCLs that were either blister packed or vial packed. A small percentage of the lenses testedpositive for contamination.

  16. Question time.

    Science.gov (United States)

    Taylor, Jennifer

    Choosing to train as a nurse is a major decision, rife with different emotions and considerations. Regardless of what point you have reached in your studies, whether you are studying towards a degree or diploma, whatever your age and whether you are from the UK or overseas, you face common challenges. These include surviving financially, juggling study and clinical placements, learning new information and addressing patients' needs. While the profession certainly offers exciting opportunities, nursing students in 2006 face a range of uncertainties. There have been cuts and freezes to existing and vacant posts across NHS trusts, while students from overseas face the additional problem that band 5 and 6 nursing posts have been removed from the Home Office's shortage occupation list. Will there be enough mentors to teach students? Will there be jobs when they qualify? How can students survive financially? Will overseas students be able to stay once qualified? NT put students' key questions to a panel of experts and influential figures.

  17. Comparison of Occurrence of Free Volumes for Rigid Gas Permeable and Soft Contact Lenses.

    Science.gov (United States)

    Filipecka, Katarzyna; Budaj, Mariusz; Miskowiak, Bogdan; Makowska-Janusik, Małgorzata; Filipecki, Jacek

    2015-01-01

    The polymeric materials: hydrogel, silicone--hydrogel and methacrylic acid are used in ophthalmology for the manufacture of contact lenses. It is important to research the structure of these materials, mainly the prevalence of free volumes. The study has been conducted in order to comparison the presence of free volume gaps in the structure of the polymer soft contact lenses: Etafilcon A (hydrogel), Narafilcon A (silicone-hydrogel) and the polymer rigid gas permeable (RGP) contact lens (Fluor-Silicon-Methacrylat-Copolymer). In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses. Three types of polymer contact lenses were used as materials: Etafilcon A, Narafilcon A and Fluor-Silicon-Methacrylat-Copolymer. The study was done by means of positron annihilation lifetime spectroscopy (PALS). As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses. The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. There is a clear difference in the free volume sizes and their fractions between measured contact lenses are connected with oxygen permeability in these lenses. The results lead to the following connection: contact lenses of higher oxygen permeability coefficients and a water content of less, have more and larger free volumes than contact lenses of less oxygen permeability coefficient.

  18. Probing the dark side of the Universe with weak gravitational lensing effects

    International Nuclear Information System (INIS)

    Fu Li-Ping; Fan Zu-Hui

    2014-01-01

    Arising from gravitational deflections of light rays by large-scale structures in the Universe, weak-lensing effects have been recognized as one of the most important probes in cosmological studies. In this paper, we review the main progress in weak-lensing analyses, and discuss the challenges in future investigations aiming to understand the dark side of the Universe with unprecedented precisions. (invited reviews)

  19. Objective and subjective performance of scleral lenses and new advances in scleral lens technologies

    OpenAIRE

    Visser, E.S.

    2015-01-01

    Scleral lenses are widely recognized for their ability to markedly improve quality of life and giving back patients their ability to perform daily activities, mainly as a result of restoring visual function and/or reduction of ocular discomfort and pain.Scleral lenses are an important front-line tool for managing many corneal disorders refractory to other treatment measures and that otherwise would require keratoplasty. These disorders include conditions in which the cornea requires suitable ...

  20. Efficient simulation of autofluorescence effects in microscopic lenses

    DEFF Research Database (Denmark)

    Gross, Herbert; Rodenko, Olga; Esslinger, Moritz

    2015-01-01

    The use of fluorescence in microscopy is a well known technology today. Due to the autofluorescence of the materials of the optical system components, the contrast of the images is degraded. The calculation of autofluorescense usually is performed by brute force methods as volume scattering...... be performed properly. Some necessary approximations produce negligible errors. The improvement in run time is in the range of 104 . It is shown with some practical examples of microscopic lenses, that the results are comparable with conventional methods. The limitations and the consequences for questions...

  1. Scanning Miniature Microscopes without Lenses

    Science.gov (United States)

    Wang, Yu

    2009-01-01

    The figure schematically depicts some alternative designs of proposed compact, lightweight optoelectronic microscopes that would contain no lenses and would generate magnified video images of specimens. Microscopes of this type were described previously in Miniature Microscope Without Lenses (NPO - 20218), NASA Tech Briefs, Vol. 22, No. 8 (August 1998), page 43 and Reflective Variants of Miniature Microscope Without Lenses (NPO 20610), NASA Tech Briefs, Vol. 26, No. 9 (September 1999), page 6a. To recapitulate: In the design and construction of a microscope of this type, the focusing optics of a conventional microscope are replaced by a combination of a microchannel filter and a charge-coupled-device (CCD) image detector. Elimination of focusing optics reduces the size and weight of the instrument and eliminates the need for the time-consuming focusing operation. The microscopes described in the cited prior articles contained two-dimensional CCDs registered with two-dimensional arrays of microchannels and, as such, were designed to produce full two-dimensional images, without need for scanning. The microscopes of the present proposal would contain one-dimensional (line image) CCDs registered with linear arrays of microchannels. In the operation of such a microscope, one would scan a specimen along a line perpendicular to the array axis (in other words, one would scan in pushbroom fashion). One could then synthesize a full two-dimensional image of the specimen from the line-image data acquired at one-pixel increments of position along the scan. In one of the proposed microscopes, a beam of unpolarized light for illuminating the specimen would enter from the side. This light would be reflected down onto the specimen by a nonpolarizing beam splitter attached to the microchannels at their lower ends. A portion of the light incident on the specimen would be reflected upward, through the beam splitter and along the microchannels, to form an image on the CCD. If the

  2. Modern scleral lenses part I: clinical features.

    Science.gov (United States)

    Visser, Esther-Simone; Visser, Rients; van Lier, Henk J J; Otten, Henny M

    2007-01-01

    To evaluate the indications for modern scleral lenses and their clinical performance in patients who were fitted with scleral lenses at the authors' practices. In this cross-sectional survey, all the necessary data were obtained at the first follow-up visit during the 5-month study period. There were four types of scleral lenses: spherical, front-surface toric, back-surface toric, and bitoric. The preformed scleral lens fitting technique developed at Visser Contact Lens Practice was used in all patients. The lenses were cut by precise Sub Micron Lathing from a Boston Equalens II blank at Procornea. Visual acuity and slitlamp findings were recorded. A specially designed classification for scleral lens fitting was used to investigate clinical performance. The largest proportion of the 178 patients (284 eyes) were diagnosed with keratoconus (143 [50.4%] eyes) followed by postpenetrating keratoplasty (56 [19.7%] eyes). The remaining diagnoses were irregular astigmatism, keratitis sicca, corneal dystrophy, and multiple diagnoses. The ratio of spherical to back-surface toric designs was 1:1.1. Clinical examination showed sharp increases in visual acuity (median increase, 0.45) and safe physiologic responses of the anterior eye. All the patients could continue to wear scleral lenses, with 79.2% with the same lens parameters. Several types of corneal abnormality were managed successfully with modern scleral lenses. The main indication was optical correction of an irregular corneal surface. Satisfactory clinical performance meant that all the patients could continue to wear their scleral lenses.

  3. Investigations of Galaxy Clusters Using Gravitational Lensing

    Energy Technology Data Exchange (ETDEWEB)

    Wiesner, Matthew P. [Northern Illinois Univ., DeKalb, IL (United States)

    2014-08-01

    In this dissertation, we discuss the properties of galaxy clusters that have been determined using strong and weak gravitational lensing. A galaxy cluster is a collection of galaxies that are bound together by the force of gravity, while gravitational lensing is the bending of light by gravity. Strong lensing is the formation of arcs or rings of light surrounding clusters and weak lensing is a change in the apparent shapes of many galaxies. In this work we examine the properties of several samples of galaxy clusters using gravitational lensing. In Chapter 1 we introduce astrophysical theory of galaxy clusters and gravitational lensing. In Chapter 2 we examine evidence from our data that galaxy clusters are more concentrated than cosmology would predict. In Chapter 3 we investigate whether our assumptions about the number of galaxies in our clusters was valid by examining new data. In Chapter 4 we describe a determination of a relationship between mass and number of galaxies in a cluster at higher redshift than has been found before. In Chapter 5 we describe a model of the mass distribution in one of the ten lensing systems discovered by our group at Fermilab. Finally in Chapter 6 we summarize our conclusions.

  4. Triglycerides : Frequently Asked Questions

    Science.gov (United States)

    ... Questions Why are triglycerides important? The amount of triglycerides (or blood fats) in blood are one important barometer of metabolic health; high levels are associated with coronary heart disease, diabetes and fatty liver disease. Metabolism refers to the chemical process that converts the ...

  5. GEMINI/GMOS SPECTROSCOPY OF 26 STRONG-LENSING-SELECTED GALAXY CLUSTER CORES

    International Nuclear Information System (INIS)

    Bayliss, Matthew B.; Gladders, Michael D.; Koester, Benjamin P.; Hennawi, Joseph F.; Sharon, Keren; Dahle, Haakon; Oguri, Masamune

    2011-01-01

    We present results from a spectroscopic program targeting 26 strong-lensing cluster cores that were visually identified in the Sloan Digital Sky Survey (SDSS) and the Second Red-Sequence Cluster Survey (RCS-2). The 26 galaxy cluster lenses span a redshift range of 0.2 Vir = 7.84 x 10 14 M sun h -1 0.7 , which is somewhat higher than predictions for strong-lensing-selected clusters in simulations. The disagreement is not significant considering the large uncertainty in our dynamical data, systematic uncertainties in the velocity dispersion calibration, and limitations of the theoretical modeling. Nevertheless our study represents an important first step toward characterizing large samples of clusters that are identified in a systematic way as systems exhibiting dramatic strong-lensing features.

  6. 'Colored' and Decorative Contact Lenses: A Prescription Is a Must

    Science.gov (United States)

    ... these looks with decorative contact lenses (sometimes called “fashion,” “costume,” or “colored” contact lenses). These lenses don’ ... Wear Decorative or “Colored” Contact Lenses An entertainment industry artist from American Horror Story and the FDA ...

  7. Tevatron Electron Lenses: Design and Operation

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, Vladimir; /Fermilab; Bishofberger, Kip; /Los Alamos; Kamerdzhiev, Vsevolod; /Fermilab; Kozub, Sergei; /Serpukhov, IHEP; Kufer, Matthew; Kuznetsov, Gennady; Martinez, Alexander; Olson, Marvin; Pfeffer, Howard; Saewert, Greg; Scarpine, Vic; /Fermilab /SLAC /Fermilab /Serpukhov, IHEP /Novosibirsk, IYF /Serpukhov, IHEP /Fermilab

    2008-08-01

    The beam-beam effects have been the dominating sources of beam loss and lifetime limitations in the Tevatron proton-antiproton collider [1]. Electron lenses were originally proposed for compensation of electromagnetic long-range and head-on beam-beam interactions of proton and antiproton beams [2]. Results of successful employment of two electron lenses built and installed in the Tevatron are reported in [3,4,5]. In this paper we present design features of the Tevatron electron lenses (TELs), discuss the generation of electron beams, describe different modes of operation and outline the technical parameters of various subsystems.

  8. Thin Film Coating Technology For Ophthalmic Lenses

    Science.gov (United States)

    Guenther, K. H.

    1986-05-01

    Coating of ophthalmic lenses is an application of high-vacuum coating technology which must satisfy not only physical and technical requirements but also customer demands with respect to aesthetics, color fidelity, and exchangeability of coated ophthalmic lenses. Because this application caters specifically to the consumer market, ophthalmic lenses are subject to certain fashion trends which frequently require quick adaptation of the coating technique. The state-of-the-art of ophthalmic lens coating is reviewed in this paper, with particular emphasis on the durability requirements in daily use by untrained consumers as well as on the applicable testing methods.

  9. Energy questions

    International Nuclear Information System (INIS)

    1980-01-01

    This Working Paper is about the energy crisis. Its chief aim is to give a lot of information about the various sources of energy and the problems about the supply and the use of them. It is in five parts. Part One illustrates the importance of energy in the world economy and particularly in Britain. Part Two describes the various sources of energy; coal, oil, gas, electricity and nuclear, and discusses the renewable sources and energy conservation. Part Three gives arguments for and against a nuclear future. Part Four describes the debate in the Churches on the nuclear option and Part Five sets out some theological and ethical themes relevant to responsible decision making on these matters. (author)

  10. Questions and Questioning Techniques: A View of Indonesian Students’ Preferences

    Directory of Open Access Journals (Sweden)

    Debora Tri Ragawanti

    2009-01-01

    Full Text Available This study investigated students’ preference on teacher’s questions and questionings techniques and more importantly on how they could facilitate or impede their learning. The results on teacher’s questioning techniques showed that random nomination was more preferred than pre-arranged format nomination. In addition, techniques of nominating volunteering students and of giving wait-time were disliked by most student-respondents. As for types of question, the yes/no question was favored by most of the respondents. Different from the yes/no question, the number of respondents leaning forward to the analysis question, questions about fact of life, and questions to state opinion did not show a significant difference from the number of those leaning against the same questions.

  11. Stress-Strain Measurements of Semi-Aquatic Snake Lenses

    Science.gov (United States)

    Lama, Nisha; Norwood, David, , Dr.; Fontenot, Cliff, , Dr.; Wallace, Addison; Koduri, Mahitha; Allain, Rhett, , Dr.

    It is of interest to understand the mechanism by which semi-aquatic maintain visual acuity when moving from land to underwater. Toward that end, we are interested in the mechanical properties of snake lenses and how this might affect the ability of snakes to deform the lens and thus alter the lens power. In this presentation, we will present data taken with a force sensor and a rotary motion sensor to measure, in one shot, force versus displacement, from which we estimate mechanical properties of stress and strain of the eye lens of a water snake. We will compare the results from lenses freshly removed from snake to those that have been stored. More importantly though, we will compare results from one species of semi-aquatic snakes to the other species of interest

  12. Photometry of High-Redshift Gravitationally Lensed Type Ia Supernovae

    Science.gov (United States)

    Haynie, Annastasia

    2018-01-01

    Out of more than 1100 well-identified Type Ia Supernovae, only roughly 10 of them are at z> 1.5. High redshift supernovae are hard to detect but this is made easier by taking advantage of the effects of gravitational lensing, which magnifies objects in the background field of massive galaxy clusters. Supernova Nebra (z= ~1.8), among others, was discovered during observations taken as part of the RELICS survey, which focused on fields of view that experience strong gravitational lensing effects. SN Nebra, which sits behind galaxy cluster Abell 1763, is magnified and therefore appears closer and easier to see than with HST alone. Studying high-redshift supernovae like SN Nebra is an important step towards creating cosmological models that accurately describe the behavior of dark energy in the early Universe. Recent efforts have been focused on improving photometry and the building and fitting of preliminary light curves.

  13. Nuclear questions

    Energy Technology Data Exchange (ETDEWEB)

    Durrani, M. [Physics World (United Kingdom)

    2006-01-01

    The future of nuclear power has returned to centre stage. Freezing weather on both sides of the Atlantic and last month's climate-change talks in Montreal have helped to put energy and the future of nuclear power right back on the political agenda. The issue is particularly pressing for those countries where existing nuclear stations are reaching the end of their lives. In the UK, prime minister Tony Blair has commissioned a review of energy, with a view to deciding later this year whether to build new nuclear power plants. The review comes just four years after the Labour government published a White Paper on energy that said the country should keep the nuclear option open but did not follow this up with any concrete action. In Germany, new chancellor and former physicist Angela Merkel is a fan of nuclear energy and had said she would extend the lifetime of its nuclear plants beyond 2020, when they are due to close. However, that commitment has had to be abandoned, at least for the time being, following negotiations with her left-wing coalition partners. The arguments in favour of nuclear power will be familiar to all physicists - it emits almost no carbon dioxide and can play a vital role in maintaining a diverse energy supply. To over-rely on imported supplies of oil and gas can leave a nation hostage to fortune. The arguments against are equally easy to list - the public is scared of nuclear power, it generates dangerous waste with potentially huge clean-up costs, and it is not necessarily cheap. Nuclear plants could also be a target for terrorist attacks. Given political will, many of these problems can be resolved, or at least tackled. China certainly sees the benefits of nuclear power, as does Finland, which is building a new 1600 MW station - the world's most powerful - that is set to open in 2009. Physicists, of course, are essential to such developments. They play a vital role in ensuring the safety of such plants and developing new types of

  14. Cosmological applications of strong gravitational lensing

    DEFF Research Database (Denmark)

    Paraficz, Danuta

    value of the energy density of the two above components, together with measuring the Hubble constant that determines the age of the Universe, is a major goal of modern astrophysics. An interesting method for estimating these parameters is strong gravitational lensing of quasars (QSOs). As shown...... by Refsdal (1964), H0, !m and !! can be measured based on the time delay ("t) between multiply lensed images of QSOs, because "t depends on H0 and on the distances to lens and source, hence!m and !!. Determination of cosmological parameters using gravitational lensing suffers from some degeneracies......, but it is based on well understood physics and unlike distance ladder methods there are no calibration issues. Moreover, it has an advantage over some of the leading methods (such as Type Ia SNe) in that it is a purely cosmological approach. In this thesis, the property of strong gravitational lensing - time...

  15. Characterisation of adaptive fluidic silicone membrane lenses

    CSIR Research Space (South Africa)

    Schneider, F

    2009-09-01

    Full Text Available In this paper the auhtors compare the performance and optical quality of two types of adaptive fluidic silicone-membrane lenses. The membranes feature either a homogeneous thickness, or they are shaped resulting in an inhomogeneous cross...

  16. Disposable contact lenses in penetrating keratoplasty.

    Science.gov (United States)

    Arora, R; Gupta, S; Taneja, M; Raina, U K; Mehta, D K

    2000-07-01

    To evaluate the therapeutic efficacy of disposable contact lenses in management of complications after keratoplasty. Twenty-eight patients with various post keratoplasty complications were fit with disposable contact lenses (45% Vifilcon A and 55% water content). Indications for lens use included persistent epithelial defects, wound leak, graft edema, dry eye and protection of normal corneal epithelium. Success was obtained with the therapeutic use of disposable lenses in 20 of the 28 cases. The best results were seen in maintenance and restoration of healthy ocular surface and small wound leaks. Stromal graft edema with no epithelial involvement was the major area of therapeutic failure. Disposable contact lenses are an attractive low cost option in the management of complications after keratoplasty. They are particularly useful in maintaining a healthy ocular surface, providing symptomatic relief and avoiding resurgery in patients with small wound leaks.

  17. Gravitational Lensing Mass Mapping with Gaussian Processes

    Science.gov (United States)

    Schneider, Michael; Ng, Karen; Dawson, William; Marshall, Phil; Meyers, Joshua; Bard, Deborah

    2018-01-01

    We infer gravitational lensing shear and convergence fields from galaxy ellipticity catalogs under a Gaussian Process prior for the lensing potential. We demonstrate the performance of our algorithm with simulated Gaussian-distributed cosmological lensing shear maps and a reconstruction of the mass distribution of the merging galaxy cluster Abell 781 using galaxy ellipticities measured with the Deep Lens Survey. Given interim posterior samples of lensing shear or convergence fields on the sky, we describe an algorithm to infer cosmological parameters via lens field marginalization. In the most general formulation of our algorithm we make no assumptions about weak shear orGaussian-distributed shape noise or shears. Because we require solutions and matrix determinants of a linear system of dimension that scales with the number of galaxies, we present computational performance metrics with approximate algorithms that introduce sparsity in the Gaussian Process kernel.

  18. Comments on the Gravitational lensing Magnification

    OpenAIRE

    Takashi, HAMANA; Astronomical Institute, Tohoku University

    1998-01-01

    We rederive a relation between gravitational lensing magnification relative to the standard Friedmann distance and one relative to the Dyer-Roeder distance by investigating the null geodesic deviation equation. We show that the relation comes from a natural consequence of the definition of the lensing magnification matrices and is not based on the averaging of the magnifications, which has conventionally been used to derive it. We therefore conclude that the relation is true for each individu...

  19. Comments on the gravitational lensing magnification

    OpenAIRE

    Hamana, Takashi

    1998-01-01

    We rederive a relation between gravitational lensing magnification relative to the standard Friedmann distance and one relative to the Dyer-Roeder distance by investigating the null geodesic deviation equation. We show that the relation comes from a natural consequence of the definition of the lensing magnification matrices and is not based on the averaging of the magnifications, which has conventionally been used to derive it. We therefore conclude that the relation is true for each individu...

  20. Planck 2015 results: XV. Gravitational lensing

    DEFF Research Database (Denmark)

    Ade, P. A R; Aghanim, N.; Arnaud, M.

    2016-01-01

    We present the most significant measurement of the cosmic microwave background (CMB) lensing potential to date (at a level of 40σ), using temperature and polarization data from the Planck 2015 full-mission release. Using a polarization-only estimator, we detect lensing at a significance of 5σ. We......-scale temperature anisotropies, detecting a cross-correlation at the 3σ level, as expected because of dark energy in the concordance ΛCDM model....

  1. Electron Lenses for particle collimation in LHC

    CERN Document Server

    Shiltsev, V

    2008-01-01

    Electron Lenses built and installed in Tevatron have proven themselves as safe and very reliable instruments which can be effectively used in hadron collider operation for a number of applications, including compensation of beam-beam effects , DC beam removal from abort gaps , as a diagnostic tool. In this presentation we – following original proposal – consider in more detail a possibility of using electron lenses with hollow electron beam for ion and proton collimation in LHC.

  2. Revised Unfilling Procedure for Solid Lithium Lenses

    Energy Technology Data Exchange (ETDEWEB)

    Leveling, A.; /Fermilab

    2003-06-03

    A procedure for unfilling used lithium lenses to has been described in Pbar Note 664. To date, the procedure has been used to disassemble lenses 20, 21, 17, 18, and 16. As a result of this work, some parts of the original procedure were found to be time consuming and ineffective. Modifications to the original procedure have been made to streamline the process and are discussed in this note. The revised procedure is included in this note.

  3. Cross-correlation of gravitational lensing from DES Science Verification data with SPT and Planck lensing

    Energy Technology Data Exchange (ETDEWEB)

    Kirk, D.; Omori, Y.; Benoit-Lévy, A.; Cawthon, R.; Chang, C.; Larsen, P.; Amara, A.; Bacon, D.; Crawford, T. M.; Dodelson, S.; Fosalba, P.; Giannantonio, T.; Holder, G.; Jain, B.; Kacprzak, T.; Lahav, O.; MacCrann, N.; Nicola, A.; Refregier, A.; Sheldon, E.; Story, K. T.; Troxel, M. A.; Vieira, J. D.; Vikram, V.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Becker, M. R.; Benson, B. A.; Bernstein, G. M.; Bernstein, R. A.; Bleem, L. E.; Bonnett, C.; Bridle, S. L.; Brooks, D.; Buckley-Geer, E.; Burke, D. L.; Capozzi, D.; Carlstrom, J. E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D' Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Eifler, T. F.; Evrard, A. E.; Flaugher, B.; Frieman, J.; Gerdes, D. W.; Goldstein, D. A.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D. J.; Jarvis, M.; Kent, S.; Kuehn, K.; Kuropatkin, N.; Lima, M.; March, M.; Martini, P.; Melchior, P.; Miller, C. J.; Miquel, R.; Nichol, R. C.; Ogando, R.; Plazas, A. A.; Reichardt, C. L.; Roodman, A.; Rozo, E.; Rykoff, E. S.; Sako, M.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Simard, G.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Thomas, D.; Wechsler, R. H.; Weller, J.

    2016-03-10

    We measure the cross-correlation between weak lensing of galaxy images and of the cosmic microwave background (CMB). The effects of gravitational lensing on different sources will be correlated if the lensing is caused by the same mass fluctuations. We use galaxy shape measurements from 139 deg$^{2}$ of the Dark Energy Survey (DES) Science Verification data and overlapping CMB lensing from the South Pole Telescope (SPT) and Planck. The DES source galaxies have a median redshift of $z_{\\rm med} {\\sim} 0.7$, while the CMB lensing kernel is broad and peaks at $z{\\sim}2$. The resulting cross-correlation is maximally sensitive to mass fluctuations at $z{\\sim}0.44$. Assuming the Planck 2015 best-fit cosmology, the amplitude of the DES$\\times$SPT cross-power is found to be $A = 0.88 \\pm 0.30$ and that from DES$\\times$Planck to be $A = 0.86 \\pm 0.39$, where $A=1$ corresponds to the theoretical prediction. These are consistent with the expected signal and correspond to significances of $2.9 \\sigma$ and $2.2 \\sigma$ respectively. We demonstrate that our results are robust to a number of important systematic effects including the shear measurement method, estimator choice, photometric redshift uncertainty and CMB lensing systematics. Significant intrinsic alignment of galaxy shapes would increase the cross-correlation signal inferred from the data; we calculate a value of $A = 1.08 \\pm 0.36$ for DES$\\times$SPT when we correct the observations with a simple IA model. With three measurements of this cross-correlation now existing in the literature, there is not yet reliable evidence for any deviation from the expected LCDM level of cross-correlation, given the size of the statistical uncertainties and the significant impact of systematic errors, particularly IAs. We provide forecasts for the expected signal-to-noise of the combination of the five-year DES survey and SPT-3G.

  4. Predicting gravitational lensing by stellar remnants

    Science.gov (United States)

    Harding, Alexander J.; Stefano, R. Di; Lépine, S.; Urama, J.; Pham, D.; Baker, C.

    2018-03-01

    Gravitational lensing provides a means to measure mass that does not rely on detecting and analysing light from the lens itself. Compact objects are ideal gravitational lenses, because they have relatively large masses and are dim. In this paper, we describe the prospects for predicting lensing events generated by the local population of compact objects, consisting of 250 neutron stars, five black holes, and ≈35 000 white dwarfs. By focusing on a population of nearby compact objects with measured proper motions and known distances from us, we can measure their masses by studying the characteristics of any lensing event they generate. Here, we concentrate on shifts in the position of a background source due to lensing by a foreground compact object. With Hubble Space Telescope, JWST, and Gaia, measurable centroid shifts caused by lensing are relatively frequent occurrences. We find that 30-50 detectable events per decade are expected for white dwarfs. Because relatively few neutron stars and black holes have measured distances and proper motions, it is more difficult to compute realistic rates for them. However, we show that at least one isolated neutron star has likely produced detectable events during the past several decades. This work is particularly relevant to the upcoming data releases by the Gaia mission and also to data that will be collected by JWST. Monitoring predicted microlensing events will not only help to determine the masses of compact objects, but will also potentially discover dim companions to these stellar remnants, including orbiting exoplanets.

  5. Question Quality in Community Question Answering Forums : A survey

    NARCIS (Netherlands)

    Baltadzhieva, Antoaneta; Chrupala, Grzegorz

    2015-01-01

    Community Question Answering websites (CQA) offer a new opportunity for users to provide, search and share knowledge. Although the idea of receiving a direct, targeted response to a question sounds very attractive, the quality of the question itself can have an important effect on the likelihood of

  6. Soft contact lenses: Basic characteristics, advantages and complications associated with their use

    Directory of Open Access Journals (Sweden)

    Milosavljević Miloš

    2016-01-01

    Full Text Available Soft contact lenses have an important place in ophthalmology, both for the correction of refractive anomalies and tor the treatment of some eye diseases. From the moment when adequately biocompatible materials were found, for a very sensitive environment such as the human eye, from early 60s of the 20th century, starts irrepressible expansion of soft contact lenses. The reason for this expansion of soft contact lenses lies in advantages they undoubtedly have in comparison to glasses, but also in comparison to hard and semi-hard contact lenses. Unfortunately, in parallel with the increasing number of users of this type of optical aids, increases the incidence of complications that can arise. Complications can be very diverse in nature and severity, and they can be classified into three major groups: symptoms of eye dryness, infections and allergic-toxic complications. Symptoms of dry eye are very common for users of contact lenses, and their occurrence is especially provoked by certain factors, such as cigarette smoke or prolonged watching the computer screen or TV. These complications are usually not so dangerous and can easily be solved by applying artificial tears. Infections are not so common and occur as a result of inadequate maintenance of contact lenses. If the symptoms are recognized early, infections are mostly stopped at the level of conjunctivitis and are treated fairly quickly and easily. Otherwise, the infection can progress to ulcerative keratitis, the most severe complication of inadequate application of soft contact lenses, and in some cases it can even lead to blindness. Allergic-toxic complications generally occur in susceptible persons and their occurrence in most cases means contraindication for further wearing of soft contact lenses. This case report underlines possible role of rheumatoid factor in estimation of the patient's response to administered therapy.

  7. Ultraviolet (UV) transmittance characteristics of daily disposable and silicone hydrogel contact lenses.

    Science.gov (United States)

    Moore, Linda; Ferreira, Jannie T

    2006-07-01

    The ultraviolet (UV) transmittance spectra of daily wear hydrogel and disposable silicone hydrogel contact lenses were measured. Average transmittance percentages were calculated for each lens for the entire UV spectrum and individually for the UVC, UVB and UVA portions of the spectrum. The significance of the differences in transmittance spectra obtained for the lenses was analysed using a one-way ANOVA planned comparisons test (alpha=0.05). The transmittance data were then used to calculate a UV protection factor (PF) for each contact lens brand tested. The PFs for 1-DAY ACUVUE MOIST (6.22), ACUVUE ADVANCE (10.02) and ACUVUE OASYS (11.96) contact lenses show that these contact lenses have superior UV-blocking capabilities. The PFs for Focus DAILIES (1.79), SofLens 1-day disposables (1.72), NIGHT & DAY (1.84), O2 Optix (1.99) and Purevision (2.62) show that these contact lenses posses more modest UV-blocking characteristics. This paper reviews the importance of protection of the anterior ocular surface from UV damage and quantifies the protection afforded by selected commercially available disposable contact lenses.

  8. Effect of Unifocal versus Multifocal Lenses on Cervical Spine Posture in Patients with Presbyopia.

    Science.gov (United States)

    Abbas, Rami L; Houri, Mohamad T; Rayyan, Mohammad M; Hamada, Hamada Ahmad; Saab, Ibtissam M

    2018-04-04

    There are many environmental considerations which may or may not lead to the development of faulty cervical mechanics. The design of near vision lenses could contribute to the development of such cervical dysfunction and consequently neck pain. Decision making regarding proper type of lens prescription seems important for presbyopic individuals. To investigate the effect of unifocal and multifocal lenses on cervical posture. Thirty subjects (18 females and 12 males) participated in the study with an age range from 40 to 64 years. Each subject wore consequently both unifocal and multifocal lenses randomly while reading. Then lateral cervical spine X-ray films were taken for each subject during each lens wearing. X-ray films were analyzed with digital software (Autocad software, 2 D) to measure segmental angles of the cervical vertebrae (Occiput/C1, C1/C2, C2/C3, C3/C4, C4/C5, C5/C6, C6/C7, C3/C7, C0/C3, and occiput/C7). Higher significant extension angle in the segments C0/C7, C1/C2, C5/C6, C6/C7, and C3/C7 (p<0.05) during multifocal lenses wearing were observed in contrast with higher flexion angle between C3/C4 and C4/C5 (p<0.05) with unifocal lenses wear. Multifocal lens spectacles produces increased extension in the cervical vertebrae angles when compared with the use of unifocal lenses.

  9. Potentially pathogenic free-living amoebae in contact lenses of the asymptomatic contact lens wearers.

    Directory of Open Access Journals (Sweden)

    Maryam Niyyati

    2014-03-01

    Full Text Available Free-living amoebae (FLA including Acanthamoeba spp. and Hartmannella spp. are the causative agents of serious corneal infection especially within contact lens wearers. Thus contact lenses and their storage case could be a suitable niche for potentially pathogenic amoebae. The main objective of the present study was to evaluate the contamination of contact lenses to free living amoebae using morphological and sequencing based methods.Overall, 90 volunteers provided their contact lenses. All volunteers wore soft contact lenses. Both lenses were cultured in the same plate. Forty-eight of the volunteers were medical and dentistry student and 42 were ophthalmology attendees of hospitals in Tehran, Iran. All of the samples were inoculated to non-nutrient medium and monitored daily for the outgrowth of the amoebae. PCR and sequencing were performed using various primer pairs.Of the 90 volunteers, 9 (10% were positive for free-living amoebae outgrowth. Morphological analysis revealed that 3 isolates were belonged to Hartmannella genus according to small round cysts and 6 isolates were belonged to Acanthamoeba genus based on the star shape of endocysts. Sequencing revealed that Acanthamoeba belonged to T4, T3 and T5 genotype. Hartmannella were also belonged to vermiformis species.The presence of potentially pathogenic free living amoebae including Acanthamoeba and Hartmannella could be a high risk for people using soft contact lenses. These results revealed that improved clarification and professional recommendations for contact lens wearers is of utmost importance.

  10. Biological and Clinical Implications of Lysozyme Deposition on Soft Contact Lenses.

    Science.gov (United States)

    Omali, Negar Babaei; Subbaraman, Lakshman N; Coles-Brennan, Chantal; Fadli, Zohra; Jones, Lyndon W

    2015-07-01

    Within a few minutes of wear, contact lenses become rapidly coated with a variety of tear film components, including proteins, lipids, and mucins. Tears have a rich and complex composition, allowing a wide range of interactions and competitive processes, with the first event observed at the interface between a contact lens and tear fluid being protein adsorption. Protein adsorption on hydrogel contact lenses is a complex process involving a variety of factors relating to both the protein in question and the lens material. Among tear proteins, lysozyme is a major protein that has both antibacterial and anti-inflammatory functions. Contact lens materials that have high ionicity and high water content have an increased affinity to accumulate lysozyme during wear, when compared with other soft lens materials, notably silicone hydrogel lenses. This review provides an overview of tear film proteins, with a specific focus on lysozyme, and examines various factors that influence protein deposition on contact lenses. In addition, the impact of lysozyme deposition on various ocular physiological responses and bacterial adhesion to lenses and the interaction of lysozyme with other tear proteins are reviewed. This comprehensive review suggests that deposition of lysozyme on contact lens materials may provide a number of beneficial effects during contact lens wear.

  11. VQABQ: Visual Question Answering by Basic Questions

    KAUST Repository

    Huang, Jia-Hong

    2017-03-19

    Taking an image and question as the input of our method, it can output the text-based answer of the query question about the given image, so called Visual Question Answering (VQA). There are two main modules in our algorithm. Given a natural language question about an image, the first module takes the question as input and then outputs the basic questions of the main given question. The second module takes the main question, image and these basic questions as input and then outputs the text-based answer of the main question. We formulate the basic questions generation problem as a LASSO optimization problem, and also propose a criterion about how to exploit these basic questions to help answer main question. Our method is evaluated on the challenging VQA dataset and yields state-of-the-art accuracy, 60.34% in open-ended task.

  12. Precise LIGO lensing rate predictions for binary black holes

    Science.gov (United States)

    Ng, Ken K. Y.; Wong, Kaze W. K.; Broadhurst, Tom; Li, Tjonnie G. F.

    2018-01-01

    We show how LIGO is expected to detect coalescing binary black holes at z >1 that are lensed by the intervening galaxy population. Gravitational magnification, μ , strengthens gravitational-wave signals by √{μ } without altering their frequencies, which if unrecognized leads to an underestimate of the event redshift and hence an overestimate of the binary mass. High magnifications can be reached for coalescing binaries, because the region of intense gravitational-wave emission during coalescence is so small (˜100 km ), permitting very close projections between lensing caustics and gravitational-wave events. Our simulations use the current LIGO event-based mass function and incorporate accurate waveforms convolved with the LIGO power spectral density. Importantly, we include the detection dependence on sky position and orbital orientation, which for the LIGO configuration translates into a wide spread in observed redshifts and chirp masses. Currently, we estimate a detectable rate of lensed events 0. 06-0.02+0.02 yr-1 that rises to 5-3+5 yr-1 at LIGO design sensitivity limit, depending on the high redshift rate of black hole coalescence.

  13. Which Are Our Next Questions?

    Science.gov (United States)

    Costa, Manuel Joao

    2013-01-01

    The importance of posing the best questions in research studies in Biochemistry and Molecular Biology (BMB) is undisputed. Researchers may spend long hours reflecting and discussing with colleagues how to improve a certain question they have in mind. The best questions are always original,

  14. Gravitationally Lensed Quasars in Gaia: II. Discovery of 24 Lensed Quasars

    Science.gov (United States)

    Lemon, Cameron A.; Auger, Matthew W.; McMahon, Richard G.; Ostrovski, Fernanda

    2018-04-01

    We report the discovery, spectroscopic confirmation and preliminary characterisation of 24 gravitationally lensed quasars identified using Gaia observations. Candidates were selected in the Pan-STARRS footprint with quasar-like WISE colours or as photometric quasars from SDSS, requiring either multiple detections in Gaia or a single Gaia detection near a morphological galaxy. The Pan-STARRS grizY images were modelled for the most promising candidates and 60 candidate systems were followed up with the William Herschel Telescope. 13 of the lenses were discovered as Gaia multiples and 10 as single Gaia detections near galaxies. We also discover 1 lens identified through a quasar emission line in an SDSS galaxy spectrum. The lenses have median image separation 2.13″ and the source redshifts range from 1.06 to 3.36. 4 systems are quadruply-imaged and 20 are doubly-imaged. Deep CFHT data reveal an Einstein ring in one double system. We also report 12 quasar pairs, 10 of which have components at the same redshift and require further follow-up to rule out the lensing hypothesis. We compare the properties of these lenses and other known lenses recovered by our search method to a complete sample of simulated lenses to show the lenses we are missing are mainly those with small separations and higher source redshifts. The initial Gaia data release only catalogues all images of ˜ 30% of known bright lensed quasars, however the improved completeness of Gaia data release 2 will help find all bright lensed quasars on the sky.

  15. Relative radiosensitivity of rat lenses as a function of age

    International Nuclear Information System (INIS)

    Merriam, G.R. Jr.; Szechter, A.

    1975-01-01

    The effect of age on the development of radiation cataracts in rat lenses has been investigated using the Columbia--Sherman rat as an experiment model. A detailed pattern of age dependence was obtained at several different dose levels. In general at dose levels from 200 to 300 rads the lens changes occurred sooner and progressed faster in the adult lenses than in young lenses. In the dose range from 300 rads to 900 rads opacities developed sooner in the young lenses but progression was faster and severe opacities developed sooner in adult lenses. Above 900 rads opacities developed sooner and progressed faster in the young lenses. (U.S.)

  16. The social question revisited

    DEFF Research Database (Denmark)

    Kenneth, Petersson; Olsson, Ulf; Krejsler, John B.

    2015-01-01

    The focus of this chapter is the re-installation of the social question as a historical practice. The purpose is to investigate how historic figures return and are applied in contemporary political discourses, more precisely in the context of education, education policy and teacher education....... Contemporary as well as the 19th century debates about the social dimension and the social question deal with social integration. The recent London Communiqué of Ministers emphasizes the importance of the social dimension in higher education in terms of fostering social cohesion, reducing inequalities...... the diversity of relevant populations “without obstacles related to their social and economic background”. In the 19th century the social question was raised in a context of industrialization of societies. It dealt with suggestions about disintegration of predominant social structures and the management...

  17. DESIGN OF THE MULTIORDER INTRAOCULAR LENSES

    Directory of Open Access Journals (Sweden)

    V. G. Kolobrodov

    2015-01-01

    Full Text Available Intraocular lenses (IOLs are used to replace the natural crystalline lens of the eye. Just few basic designs of IOLs are used clinically. Multiorder diffractive lenses (MODL which operate simultaneously in several diffractive orders were proposed to decrease the chromatic aberration. Properties analysis of MODL showed a possibility to use them to develop new designs of IOLs. The purpose of this paper was to develop a new method of designing of multiorder intraocular lenses with decreased chromatic aberration. The theoretical research of the lens properties was carried out. The diffraction efficiency dependence with the change of wavelength was studied. A computer simulation of MODL in a schematic model of the human eye was carried out. It is found the capability of the multiorder diffractive lenses to focus polychromatic light into a segment on the optical axis with high diffraction efficiency. At each point of the segment is present each component of the spectral range, which will build a color image in combination. The paper describes the new design method of intraocular lenses with reduced chromaticism and with endless adaptation. An optical system of an eye with an intraocular lens that provides sharp vision of objects located at a distance of 700 mm to infinity is modeled.

  18. Modern scleral contact lenses: A review.

    Science.gov (United States)

    van der Worp, Eef; Bornman, Dina; Ferreira, Daniela Lopes; Faria-Ribeiro, Miguel; Garcia-Porta, Nery; González-Meijome, José M

    2014-08-01

    Scleral contact lenses (ScCL) have gained renewed interest during the last decade. Originally, they were primarily used for severely compromised eyes. Corneal ectasia and exposure conditions were the primary indications. However, the indication range of ScCL in contact lens practices seems to be expanding, and it now increasingly includes less severe and even non-compromised eyes, too. All lenses that partly or entirely rest on the sclera are included under the name ScCL in this paper; although the Scleral Lens Education Society recommends further classification. When a lens partly rests on the cornea (centrally or peripherally) and partly on the sclera, it is called a corneo-scleral lens. A lens that rests entirely on the sclera is classified as a scleral lens (up to 25 mm in diameter maximum). When there is full bearing on the sclera, further distinctions of the scleral lens group include mini-scleral and large-scleral lenses. This manuscript presents a review of the current applications of different ScCL (all types), their fitting methods, and their clinical outcomes including potential adverse events. Adverse events with these lenses are rare, but the clinician needs to be aware of them to avoid further damage in eyes that often are already compromised. The use of scleral lenses for non-pathological eyes is discussed in this paper. Copyright © 2014 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  19. CMB-lensing beyond the Born approximation

    International Nuclear Information System (INIS)

    Marozzi, Giovanni; Fanizza, Giuseppe; Durrer, Ruth; Dio, Enea Di

    2016-01-01

    We investigate the weak lensing corrections to the cosmic microwave background temperature anisotropies considering effects beyond the Born approximation. To this aim, we use the small deflection angle approximation, to connect the lensed and unlensed power spectra, via expressions for the deflection angles up to third order in the gravitational potential. While the small deflection angle approximation has the drawback to be reliable only for multipoles ℓ ∼< 2500, it allows us to consistently take into account the non-Gaussian nature of cosmological perturbation theory beyond the linear level. The contribution to the lensed temperature power spectrum coming from the non-Gaussian nature of the deflection angle at higher order is a new effect which has not been taken into account in the literature so far. It turns out to be the leading contribution among the post-Born lensing corrections. On the other hand, the effect is smaller than corrections coming from non-linearities in the matter power spectrum, and its imprint on CMB lensing is too small to be seen in present experiments.

  20. Strong lensing by fermionic dark matter in galaxies

    Science.gov (United States)

    Gómez, L. Gabriel; Argüelles, C. R.; Perlick, Volker; Rueda, J. A.; Ruffini, R.

    2016-12-01

    It has been shown that a self-gravitating system of massive keV fermions in thermodynamic equilibrium correctly describes the dark matter (DM) distribution in galactic halos (from dwarf to spiral and elliptical galaxies) and that, at the same time, it predicts a denser quantum core towards the center of the configuration. Such a quantum core, for a fermion mass in the range of 50 keV ≲m c2≲345 keV , can be an alternative interpretation of the central compact object in Sgr A*, traditionally assumed to be a black hole (BH). We present in this work the gravitational lensing properties of this novel DM configuration in nearby Milky-Way-like spiral galaxies. We describe the lensing effects of the pure DM component both on halo scales, where we compare them to the effects of the Navarro-Frenk-White and the nonsingular isothermal sphere DM models, and near the galaxy center, where we compare them with the effects of a Schwarzschild BH. For the particle mass leading to the most compact DM core, m c2≈1 02 keV , we draw the following conclusions. At distances r ≳20 pc from the center of the lens the effect of the central object on the lensing properties is negligible. However, we show that measurements of the deflection angle produced by the DM distribution in the outer region at a few kpc, together with rotation curve data, could help to discriminate between different DM models. In the inner regions 1 0-6≲r ≲20 pc , the lensing effects of a DM quantum core alternative to the BH scenario becomes a theme of an analysis of unprecedented precision which is challenging for current technological developments. We show that at distances ˜1 0-4 pc strong lensing effects, such as multiple images and Einstein rings, may occur. Large differences in the deflection angle produced by a DM central core and a central BH appear at distances r ≲1 0-6 pc ; in this regime the weak-field formalism is no longer applicable and the exact general-relativistic formula has to be used

  1. Gravitational Lensing from a Spacetime Perspective

    Directory of Open Access Journals (Sweden)

    Perlick Volker

    2004-09-01

    Full Text Available The theory of gravitational lensing is reviewed from a spacetime perspective, without quasi-Newtonian approximations. More precisely, the review covers all aspects of gravitational lensing where light propagation is described in terms of lightlike geodesics of a metric of Lorentzian signature. It includes the basic equations and the relevant techniques for calculating the position, the shape, and the brightness of images in an arbitrary general-relativistic spacetime. It also includes general theorems on the classification of caustics, on criteria for multiple imaging, and on the possible number of images. The general results are illustrated with examples of spacetimes where the lensing features can be explicitly calculated, including the Schwarzschild spacetime, the Kerr spacetime, the spacetime of a straight string, plane gravitational waves, and others.

  2. Cosmological applications of strong gravitational lensing

    DEFF Research Database (Denmark)

    Paraficz, Danuta

    value of the energy density of the two above components, together with measuring the Hubble constant that determines the age of the Universe, is a major goal of modern astrophysics. An interesting method for estimating these parameters is strong gravitational lensing of quasars (QSOs). As shown......One of the most intriguing recent results in physics is the growing evidence that an unknown energy field and an unknown kind of matter are the major components of the Universe (70% and 30%, respectively; see e.g. Riess et al. 1998, Spergel et al. 2007). Understanding and estimating the precise...... by Refsdal (1964), H0, !m and !! can be measured based on the time delay ("t) between multiply lensed images of QSOs, because "t depends on H0 and on the distances to lens and source, hence!m and !!. Determination of cosmological parameters using gravitational lensing suffers from some degeneracies...

  3. Electron lenses for super-colliders

    CERN Document Server

    Shiltsev, Vladimir D

    2016-01-01

    This book provides a comprehensive overview of the operating principles and technology of electron lenses in supercolliders.  Electron lenses are a novel instrument for high energy particle accelerators, particularly for the energy-frontier superconducting hadron colliders, including the Tevatron, RHIC, LHC and future very large hadron colliders.  After reviewing the issues surrounding beam dynamics in supercolliders, the book offers an introduction to the electron lens method and its application.  Further chapters describe the technology behind the electron lenses which have recently been proposed, built and employed for compensation of beam-beam effects and for collimation of high-energy high-intensity beams, for compensation of space-charge effects and several other applications in accelerators. The book will be an invaluable resource for those involved in the design, construction and operation of the next generation of hadron colliders.

  4. The effect of surface treatment of silicone hydrogel contact lenses on the attachment of Acanthamoeba castellanii trophozoites.

    Science.gov (United States)

    Beattie, Tara K; Tomlinson, Alan

    2009-11-01

    To determine if plasma surface treatment of Focus Night & Day silicone hydrogel contact lenses affects the attachment of Acanthamoeba. Unworn lotrafilcon A contact lenses with (Focus Night & Day) and without surface treatment and Acuvue, conventional hydrogel lenses, were quartered before 90-min incubation with Acanthamoeba castellanii trophozoites. After incubation and rinsing, the trophozoites attached to one surface of each quarter were counted by direct light microscopy. Sixteen replicates were observed for each lens type. Logarithmic transformation of data allowed the use of parametric analysis of variance. No significant difference in attachment was established between the untreated lotrafilcon A and the conventional hydrogel lenses (Ptreatment of the native Focus Night & Day material produced a significant increase in attachment (Ptreatment to reduce lens hydrophobicity; however, this procedure results in an enhanced acanthamoebal attachment. It is possible that the silicone hydrogel lens could be at a greater risk of promoting Acanthamoeba infection if exposed to the organism because of the enhanced attachment characteristic of this material. Eye care professionals should be aware of the enhanced affinity that Acanthamoeba show for this lens and accordingly emphasise to patients the significance of appropriate lens hygiene. This is particularly important where lenses are worn in a regime that could increase the chance of exposure to the organism, i.e., 6 nights/7 days extended wear or daily wear, where lenses will be stored in a lens case, or where lenses are worn when in contact with potentially contaminated water sources, i.e., swimming or showering.

  5. Gravitational Lensing Signatures of Long Cosmic Strings

    CERN Document Server

    De Laix, A A; Vachaspati, T; Laix, Andrew A. de; Krauss, Lawrence M.; Vachaspati, Tanmay

    1997-01-01

    The gravitational lensing by long, wiggly cosmic strings is shown to produce a large number of lensed images of a background source. In addition to pairs of images on either side of the string, a number of small images outline the string due to small-scale structure on the string. This image pattern could provide a highly distinctive signature of cosmic strings. Since the optical depth for multiple imaging of distant quasar sources by long strings may be comparable to that by galaxies, these image patterns should be clearly observable in the next generation of redshift surveys such as the Sloan Digital Sky Survey.

  6. Achromatic Cooling Channel with Li Lenses

    Energy Technology Data Exchange (ETDEWEB)

    Balbekov, V. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2002-04-29

    A linear cooling channel with Li lenses, solenoids, and 201 MHz RF cavities is considered. A special lattice design is used to minimize chromatic aberrations by suppression of several betatron resonances. Transverse emittance of muon beam decreases from 2 mm to 0.5 mm at the channel of about 110 m length. Longitudinal heating is modest, therefore transmission of the channel is rather high: 96% without decay and 90% with decay. Minimal beam emittance achievable by similar channel estimated as about 0.25 mm at surface field of Li lenses 10 T.

  7. Rigid gas permeable lenses and patient management.

    Science.gov (United States)

    Terry, R; Schnider, C; Holden, B A

    1989-01-01

    The introduction of new rigid gas permeable (RGP) contact lens materials provides the practitioner with a number of alternatives for patient management. But whatever the lens materials used, problems related to the lenses, care and maintenance solutions, and patients may arise. This paper examines concerns such as parameter instability, durability of lenses, compatibility of materials and solutions, patient education and compliance, 3 and 9 o'clock staining, corneal distortion, and lid changes. Suggestions are made on ways to avoid or minimize problems related to RGP lens wear.

  8. Modern scleral contact lenses : a review

    OpenAIRE

    van der Worp, Eef; Bornman, Dina; Ferreira, Daniela Lopes; Ribeiro, Miguel Faria; Garcia-Porta, Nery; González-Méijome, José Manuel

    2014-01-01

    Scleral contact lenses (ScCL) have gained renewed interest during the last decade. Originally, they wereprimarily used for severely compromised eyes. Corneal ectasia and exposure conditions were the primaryindications. However, the indication range of ScCL in contact lens practices seems to be expanding, andit now increasingly includes less severe and even non-compromised eyes, too.All lenses that partly or entirely rest on the sclera are included under the name ScCL in this paper;although th...

  9. High-speed optical signal processing using time lenses

    DEFF Research Database (Denmark)

    Galili, Michael; Hu, Hao; Guan, Pengyu

    2015-01-01

    This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle.......This paper will discuss time lenses and their broad range of applications. A number of recent demonstrations of complex high-speed optical signal processing using time lenses will be outlined with focus on the operating principle....

  10. Analysis of luminosity distributions of strong lensing galaxies: subtraction of diffuse lensed signal

    Science.gov (United States)

    Biernaux, J.; Magain, P.; Hauret, C.

    2017-08-01

    Context. Strong gravitational lensing gives access to the total mass distribution of galaxies. It can unveil a great deal of information about the lenses' dark matter content when combined with the study of the lenses' light profile. However, gravitational lensing galaxies, by definition, appear surrounded by lensed signal, both point-like and diffuse, that is irrelevant to the lens flux. Therefore, the observer is most often restricted to studying the innermost portions of the galaxy, where classical fitting methods show some instabilities. Aims: We aim at subtracting that lensed signal and at characterising some lenses' light profile by computing their shape parameters (half-light radius, ellipticity, and position angle). Our objective is to evaluate the total integrated flux in an aperture the size of the Einstein ring in order to obtain a robust estimate of the quantity of ordinary (luminous) matter in each system. Methods: We are expanding the work we started in a previous paper that consisted in subtracting point-like lensed images and in independently measuring each shape parameter. We improve it by designing a subtraction of the diffuse lensed signal, based only on one simple hypothesis of symmetry. We apply it to the cases where it proves to be necessary. This extra step improves our study of the shape parameters and we refine it even more by upgrading our half-light radius measurement method. We also calculate the impact of our specific image processing on the error bars. Results: The diffuse lensed signal subtraction makes it possible to study a larger portion of relevant galactic flux, as the radius of the fitting region increases by on average 17%. We retrieve new half-light radii values that are on average 11% smaller than in our previous work, although the uncertainties overlap in most cases. This shows that not taking the diffuse lensed signal into account may lead to a significant overestimate of the half-light radius. We are also able to measure

  11. Probing the dark matter issue in f(R)-gravity via gravitational lensing

    International Nuclear Information System (INIS)

    Lubini, M.; Tortora, C.; Naef, J.; Jetzer, P.; Capozziello, S.

    2011-01-01

    For a general class of analytic f(R)-gravity theories, we discuss the weak field limit in view of gravitational lensing. Though an additional Yukawa term in the gravitational potential modifies dynamics with respect to the standard Newtonian limit of General Relativity, the motion of massless particles results unaffected thanks to suitable cancellations in the post-Newtonian limit. Thus, all the lensing observables are equal to the ones known from General Relativity. Since f(R)-gravity is claimed, among other things, to be a possible solution to overcome for the need of dark matter in virialized systems, we discuss the impact of our results on the dynamical and gravitational lensing analyses. In this framework, dynamics could, in principle, be able to reproduce the astrophysical observations without recurring to dark matter, but in the case of gravitational lensing we find that dark matter is an unavoidable ingredient. Another important implication is that gravitational lensing, in the post-Newtonian limit, is not able to constrain these extended theories, since their predictions do not differ from General Relativity. (orig.)

  12. Probing the dark matter issue in f(R)-gravity via gravitational lensing

    Energy Technology Data Exchange (ETDEWEB)

    Lubini, M.; Tortora, C.; Naef, J.; Jetzer, P. [Universitaet Zuerich, Institut fuer Theoretische Physik, Zuerich (Switzerland); Capozziello, S. [Universita degli studi di Napoli ' ' Federico II' ' , Dipartimento di Scienze Fisiche, Napoli (Italy); Complesso Universitario di Monte S. Angelo, Napoli (Italy); INFN Sezione di Napoli, Napoli (Italy)

    2011-12-15

    For a general class of analytic f(R)-gravity theories, we discuss the weak field limit in view of gravitational lensing. Though an additional Yukawa term in the gravitational potential modifies dynamics with respect to the standard Newtonian limit of General Relativity, the motion of massless particles results unaffected thanks to suitable cancellations in the post-Newtonian limit. Thus, all the lensing observables are equal to the ones known from General Relativity. Since f(R)-gravity is claimed, among other things, to be a possible solution to overcome for the need of dark matter in virialized systems, we discuss the impact of our results on the dynamical and gravitational lensing analyses. In this framework, dynamics could, in principle, be able to reproduce the astrophysical observations without recurring to dark matter, but in the case of gravitational lensing we find that dark matter is an unavoidable ingredient. Another important implication is that gravitational lensing, in the post-Newtonian limit, is not able to constrain these extended theories, since their predictions do not differ from General Relativity. (orig.)

  13. Lensing convergence in galaxy clustering in ΛCDM and beyond

    Science.gov (United States)

    Villa, Eleonora; Di Dio, Enea; Lepori, Francesca

    2018-04-01

    We study the impact of neglecting lensing magnification in galaxy clustering analyses for future galaxy surveys, considering the ΛCDM model and two extensions: massive neutrinos and modifications of General Relativity. Our study focuses on the biases on the constraints and on the estimation of the cosmological parameters. We perform a comprehensive investigation of these two effects for the upcoming photometric and spectroscopic galaxy surveys Euclid and SKA for different redshift binning configurations. We also provide a fitting formula for the magnification bias of SKA. Our results show that the information present in the lensing contribution does improve the constraints on the modified gravity parameters whereas the lensing constraining power is negligible for the ΛCDM parameters. For photometric surveys the estimation is biased for all the parameters if lensing is not taken into account. This effect is particularly significant for the modified gravity parameters. Conversely for spectroscopic surveys the bias is below one sigma for all the parameters. Our findings show the importance of including lensing in galaxy clustering analyses for testing General Relativity and to constrain the parameters which describe its modifications.

  14. BIASED DARK ENERGY CONSTRAINTS FROM NEGLECTING REDUCED SHEAR IN WEAK-LENSING SURVEYS

    International Nuclear Information System (INIS)

    Shapiro, Charles

    2009-01-01

    The weak gravitational lensing of distant galaxies by a large-scale structure is expected to become a powerful probe of dark energy. By measuring the ellipticities of large number of background galaxies, the subtle gravitational distortion called 'cosmic shear' can be measured and used to constrain dark energy parameters. The observed galaxy ellipticities, however, are induced not by shear but by reduced shear, which also accounts for slight magnifications of the images. This distinction is negligible for present weak-lensing surveys, but it will become more important as we improve our ability to measure and understand small-angle cosmic shear modes. I calculate the discrepancy between shear and reduced shear in the context of power spectra and cross spectra, finding the difference could be as high as 10% on the smallest accessible angular scales. I estimate how this difference will bias dark energy parameters obtained from two weak-lensing methods: weak-lensing tomography and the shear ratio method known as offset-linear scaling. For weak-lensing tomography, ignoring the effects of reduced shear will cause future surveys considered by the Dark Energy Task Force to measure dark energy parameters that are biased by amounts comparable to their error bars. I advocate that reduced shear be properly accounted for in such surveys, and I provide a semi-analytic formula for doing so. Since reduced shear cross spectra do not follow an offset-linear scaling relation, the shear ratio method is similarly biased but with smaller significance.

  15. Coatings and Tints of Spectacle Lenses

    Directory of Open Access Journals (Sweden)

    H. Zeki Büyükyıldız

    2012-10-01

    Full Text Available Spectacle lenses are made of mineral or organic (plastic materials. Various coatings and tints are applied to the spectacle lenses according to the characteristic of the lens material, and for the personal needs and cosmetic purpose. The coatings may be classified in seven groups: 1 Anti-reflection coatings, 2 Hard coatings, 3 Clean coat, 4 Mirror coatings, 5 Color tint coating (one of coloring processes, 6 Photochromic coating (one of photochromic processes, and 7 Anti-fog coatings. Anti-reflection coatings reduce unwanted reflections from the lens surfaces and increase light transmission. Hard coatings are applied for preventing the plastic lens surface from scratches and abrasion. Hard coatings are not required for the mineral lenses due to their hardness. Clean coat makes the lens surface smooth and hydrophobic. Thus, it prevents the adherence of dust, tarnish, and dirt particles on the lens surface. Mirror coatings are applied onto the sunglasses for cosmetic purpose. Color tinted and photochromic lenses are used for sun protection and absorption of the harmful UV radiations. Anti-fog coatings make the lens surface hydrophilic and prevent the coalescence of tiny water droplets on the lens surface that reduces light transmission. (Turk J Ophthalmol 2012; 42: 359-69

  16. Optical aberrations in a gas lenses

    CSIR Research Space (South Africa)

    Mafusire, C

    2010-08-01

    Full Text Available Gas lenses work on the basis that aerodynamic media can be used to generate a graded refractive index distribution which can be used to focus a laser beam. Examples of these are the spinning pipe gas lens (SPGL) and the flame lens (FL). The SPGL...

  17. GRAVITATIONAL LENSES AND UNCONVENTIONAL GRAVITY THEORIES

    NARCIS (Netherlands)

    BEKENSTEIN, JD; SANDERS, RH

    1994-01-01

    We study gravitational lensing by clusters of galaxies in the context of the generic class of unconventional gravity theories which describe gravity in terms of a metric and one or more scalar fields (called here scalar-tensor theories). We conclude that, if the scalar fields have positive energy,

  18. Modern scleral lenses part II: patient satisfaction.

    NARCIS (Netherlands)

    Visser, E.S.; Visser, R.; Lier, H.J.J. van; Otten, H.M.

    2007-01-01

    PURPOSE: To evaluate the subjective performance of modern scleral lenses in patients of the clinics of Visser Contact Lens Practice. METHODS: In this cross-sectional survey, all the necessary data were collected at the first follow-up visit during the 5-month study period. In accordance with the

  19. Studying dark matter haloes with weak lensing

    NARCIS (Netherlands)

    Velander, Malin Barbro Margareta

    2012-01-01

    Our Universe is comprised not only of normal matter but also of unknown components: dark matter and dark energy. This Thesis recounts studies of dark matter haloes, using a technique known as weak gravitational lensing, in order to learn more about the nature of these dark components. The haloes

  20. Quantum Spin Lenses in Atomic Arrays

    Directory of Open Access Journals (Sweden)

    A. W. Glaetzle

    2017-09-01

    Full Text Available We propose and discuss quantum spin lenses, where quantum states of delocalized spin excitations in an atomic medium are focused in space in a coherent quantum process down to (essentially single atoms. These can be employed to create controlled interactions in a quantum light-matter interface, where photonic qubits stored in an atomic ensemble are mapped to a quantum register represented by single atoms. We propose Hamiltonians for quantum spin lenses as inhomogeneous spin models on lattices, which can be realized with Rydberg atoms in 1D, 2D, and 3D, and with strings of trapped ions. We discuss both linear and nonlinear quantum spin lenses: in a nonlinear lens, repulsive spin-spin interactions lead to focusing dynamics conditional to the number of spin excitations. This allows the mapping of quantum superpositions of delocalized spin excitations to superpositions of spatial spin patterns, which can be addressed by light fields and manipulated. Finally, we propose multifocal quantum spin lenses as a way to generate and distribute entanglement between distant atoms in an atomic lattice array.

  1. X-ray lenses with large aperture

    International Nuclear Information System (INIS)

    Simon, Markus

    2010-01-01

    Up to now, most X-ray imaging setups are based on absorption contrast imaging. There is a demand for focused X-rays in many X-ray analysis applications, either to increase the resolution of an imaging system, or, to reduce the time effort of an experiment through higher photon flux. For photon energies higher than 15 keV refractive X-ray optics are more efficient in comparison to non-refractive X-ray optics. The aim of this work was to develop X-ray lenses with large apertures and high transparency. By increasing the number of refracting surfaces while removing unnecessary lens material such lenses have been developed. Utilizing this approach the overall beam deflection angle is large with respect to the lens material it propagates through and so the transparency of the lens is increased. Within this work, X-ray lenses consisting of several thousands of prisms with an edge length in the range of micrometers have been developed and fabricated by deep X-ray lithography. Deep X-ray lithography enables high precision microstrucures with smooth sidewalls and large aspect ratios. The aperture of high-transparency X-ray lenses made this way is greater than 1 mm. They are suitable for photon energies in the range of 8 keV to 24 keV and offer a focal width of smaller than 10 μm at a transparency of around 40%. Furthermore, rolled X-ray lenses have been developed, that are made out of a microstructured polyimide film, which is cut according to the requirements regarding focal length and photon energy. The microstructured film is fabricated by molding, using an anisotropically etched silicon wafer as molding tool. Its mean roughness is in the range of nanometers. The film features prismatic structures, its surface topology is similar to an asparagus field. The measured diameter of the point focus was 18 μm to 31 μm, the calculated opticla efficiency was 37%. Future work will concentrate on increasing the aspect ratio of Prism Lenses and on increasing the rolling accuracy

  2. Microbial keratitis secondary to unintended poor compliance with scleral gas-permeable contact lenses.

    Science.gov (United States)

    Zimmerman, Aaron B; Marks, Amanda

    2014-01-01

    To report a case of neurotrophic keratitis in which scleral contact lenses improved vision from 20/100 to 20/20, however, due to poor lens care, an incident of microbial keratitis developed. A 64-year-old man with an ocular history of neurotrophic keratitis secondary to herpes simplex in each eye was successfully fit with scleral lenses. He subsequently developed microbial keratitis due to a number of risk factors. The lesion was culture negative, yet was very responsive to treatment with moxifloxacin. The lesion fully healed, and the patient did not suffer additional vision loss. This case demonstrates the ability of scleral lenses to correct visual impairments secondary to poor epithelial integrity and illustrates the importance of the practitioner providing detailed lens care instruction.

  3. Determination of refractive indices of biconvex lenses by use of a Michelson interferometer.

    Science.gov (United States)

    Chhaniwal, Vani K; Anand, Arun; Narayanamurthy, C S

    2006-06-10

    Measurements of lens parameters such as focal length, radius of curvature, and refractive index are important. We describe a measurement method that utilizes a Michelson interferometer to determine parameters of thin, convex lenses. The real fringe system formed by a Michelson interferometer is used to determine the focal lengths and the radii of curvature of the lenses. The refractive index of the lens material is determined from the thin-lens formula. We were able to determine the refractive indices to an accuracy as great as 99.97%. A detailed theoretical and experimental analysis is given.

  4. HOW TO FIND GRAVITATIONALLY LENSED TYPE Ia SUPERNOVAE

    Energy Technology Data Exchange (ETDEWEB)

    Goldstein, Daniel A.; Nugent, Peter E. [Department of Astronomy, University of California, Berkeley, CA 94720-3411 (United States)

    2017-01-01

    Type Ia supernovae (SNe Ia) that are multiply imaged by gravitational lensing can extend the SN Ia Hubble diagram to very high redshifts ( z ≳ 2), probe potential SN Ia evolution, and deliver high-precision constraints on H {sub 0}, w , and Ω{sub m} via time delays. However, only one, iPTF16geu, has been found to date, and many more are needed to achieve these goals. To increase the multiply imaged SN Ia discovery rate, we present a simple algorithm for identifying gravitationally lensed SN Ia candidates in cadenced, wide-field optical imaging surveys. The technique is to look for supernovae that appear to be hosted by elliptical galaxies, but that have absolute magnitudes implied by the apparent hosts’ photometric redshifts that are far brighter than the absolute magnitudes of normal SNe Ia (the brightest type of supernovae found in elliptical galaxies). Importantly, this purely photometric method does not require the ability to resolve the lensed images for discovery. Active galactic nuclei, the primary sources of contamination that affect the method, can be controlled using catalog cross-matches and color cuts. Highly magnified core-collapse SNe will also be discovered as a byproduct of the method. Using a Monte Carlo simulation, we forecast that the Large Synoptic Survey Telescope can discover up to 500 multiply imaged SNe Ia using this technique in a 10 year z -band search, more than an order of magnitude improvement over previous estimates. We also predict that the Zwicky Transient Facility should find up to 10 multiply imaged SNe Ia using this technique in a 3 year R -band search—despite the fact that this survey will not resolve a single system.

  5. Freshwater lenses as ecological and population sustenance, case study in the coastal wetland of Samborombón Bay (Argentina).

    Science.gov (United States)

    Tanjal, Carolina; Carol, Eleonora; Richiano, Sebastián; Santucci, Lucía

    2017-09-15

    Freshwater lenses associated to shell ridges and sand sheets exist on the coastal wetland of Samborombón Bay. As they constitute one of the most vulnerable aquifer systems, it is the aim of this study to determine the hydrogeochemical processes that condition the chemical quality of its groundwater and to assess their present and future capability as sustenance of native woods and local villagers. To achieve this, hydrogeomorphological field surveys were made and groundwater samples were taken. Results show that lenses have a mean thickness of 12m and its chemical quality depends on the dissolution of CO 2(g) and carbonates, weathering of silicates and ion exchange. Lenses can be affected by long-term climatic variability and mining. The study of morphology and geochemistry of the freshwater lenses bring lights into important information about the management of water resources and conservation of the environment. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Weak Lensing Calibrated M-T Scaling Relation of Galaxy Groups in the COSMOS Field

    NARCIS (Netherlands)

    Kettula, K.; Finoguenov, A.; Massey, R.; Rhodes, J.; Hoekstra, H.; Taylor, J.; Spinelli, P.; Tanaka, M.; Ilbert, O.; Capak, P.; McCracken, H.; Koekemoer, A.

    2013-01-01

    The scaling between X-ray observables and mass for galaxy clusters and groups is instrumental for cluster-based cosmology and an important probe for the thermodynamics of the intracluster gas. We calibrate a scaling relation between the weak lensing mass and X-ray spectroscopic temperature for 10

  7. Magic Lenses for RHIC: Compensating Beam-beam Interaction (488th Brookhaven Lecture)

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Yun [BNL Collider-Accelerator Department

    2013-07-17

    Scientists at Brookhaven Lab’s Relativistic Heavy Ion Collider (RHIC) smash atomic particles together to understand more about why the physical world works the way it does. Increasing rates of particle collisions, or luminosity, at RHIC is no small challenge, but the results—more data for better clues—are crucial for scientists trying answer big questions about the origins of matter and mass. When scientists at RHIC collide protons, they don’t hope for a head-on crash by focusing only two particles roaring toward each other from opposite directions. For all intents and purposes, that would be impossible. The scientists can smash protons because they significantly increase the likelihood of collisions by steering hundreds of billions clumped into bunches, which at RHIC are about 3.5 meters long and less than 1 millimeter tall. The particles of these bunches are all positively charged, so when they interact, they repel outwardly—think how magnets repel when their same poles are pushed together. Although this decreases the density of each bunch, reducing luminosity, scientists in Brookhaven Lab’s Collider-Accelerator Department (C-AD) have a solution. After more than seven years of development, the scientists have designed an electron-lens system that uses electrons’ negative charges to attract positively charged proton bunches and minimize their repelling tendencies. Combined with other upgrades to the RHIC accelerator complex, these lenses are important components in efforts towards the major task of doubling the luminosity for proton-proton collisions.

  8. Study of free volumes of polymer hydrogel and -silicone-hydrogel contact lenses by means of the positron annihilation lifetime spectroscopy method.

    Science.gov (United States)

    Filipecki, Jacek; Kocela, Agnieszka; Korzekwa, Witold

    2014-01-01

    Polymer materials based on hydrogel and silicone-hydrogel materials are commonly used in ophthalmology. It is important to research the structure of these materials, mainly the prevalence of free volumes. The study has been conducted in order to determine the presence of free volume gaps in the structure of polymer hydrogel and silicone-hydrogel contact lenses. In addition, to demonstrate differences in the occurrence of free volumes between types of represented contact lenses. Three different hydrogel and three different silicone-hydrogel polymer contact lenses were used as research material. The study was done by means of positron annihilation lifetime spectroscopy (PALS). As a result of the performed measurements, a graphical curve resulted which describes the relationship between the number of the annihilation acts in the time function. The study revealed the existence of three τ1, τ2 and τ3 components. Significant changes were observed in the ortho-positronium long life component τ3 and their intensities between the examined polymer contact lenses. The conducted study using the Tao-Eldrup model indicates the presence of free volume holes in all research materials. The results lead to the following connection: contact lenses of higher oxygen permeability coefficient (silicone-hydrogel contact lenses) have more and larger free volumes than contact lenses of less oxygen permeability coefficient (hydrogel contact lenses).

  9. Bacterial and fungal biofilm formation on contact lenses and their susceptibility to lens care solutions

    Directory of Open Access Journals (Sweden)

    Siddharth Kackar

    2017-01-01

    Full Text Available Background: Microbial biofilm formation on contact lenses and lens storage cases may be a risk factor for contact lens-associated corneal infections. Various types of contact lens care solutions are used to reduce microbial growths on lenses. Objectives: The present study aimed at comparing the growths of biofilms on the different contact lenses and lens cases. The study also aimed at determining the effect of lens care solutions and bacteriophage on these biofilms. Materials and Methods: One type of hard lens and two types of soft lenses were used for the study. The organisms used were Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 27853, Candida albicans ATCC 60193 and Escherichia coli ATCC 25922. Biofilm production was performed by modified O'Toole and Kolter method and effect of lens cleaning solutions and a crude coliphage on biofilms was also studied. Results were visualised using scanning electron microscopy and quantitated by colony counting method and spectrophotometric measurement of optical density (OD. Statistical analysis was done by SPSS 11.5, Kruskal–Wallis test and Chi-square test. Results: Soft lens cleaning solutions had a significant inhibitory effect (P = 0.020 on biofilm formation on soft lenses and also lens cases (P < 0.001. Soft lens cleaning solution 2 was more efficient than solution 1. However, no such inhibitory effect was observed with regard to hard lens cleaning solution, but for a significant reduction in the OD values (P < 0.001. There was no significant inhibitory effect by bacteriophages. Conclusion: This study showed the importance of selecting the appropriate lens cleaning solution to prevent biofilm production on contact lenses.

  10. Calibration of fisheye lenses for hemispherical photography

    International Nuclear Information System (INIS)

    Diaci, J.; Kolar, U.

    2000-01-01

    Hemispherical photography represents one of the most appropriate methods of estimating averages of solar radiation over extended periods of time. This method is based upon the use of extremely wide-angle fisheye lenses, which produce large projection distortion. To correctly interpret hemispherical photography we have to know the projection characteristics of the fisheye lens in combination with a camera body. This can be achieved through lens calibration. The first part of the article explains in detail the calibration method for fisheye lenses which are used to assess the solar radiation in forest ecology research. In the second part the results of calibration for fisheye lens Sigma 8 mm, f/4 (MF, N) are presented. The lens was used on a Nikon F50 camera body

  11. Astrophysical observations: lensing and eclipsing Einstein's theories.

    Science.gov (United States)

    Bennett, Charles L

    2005-02-11

    Albert Einstein postulated the equivalence of energy and mass, developed the theory of special relativity, explained the photoelectric effect, and described Brownian motion in five papers, all published in 1905, 100 years ago. With these papers, Einstein provided the framework for understanding modern astrophysical phenomena. Conversely, astrophysical observations provide one of the most effective means for testing Einstein's theories. Here, I review astrophysical advances precipitated by Einstein's insights, including gravitational redshifts, gravitational lensing, gravitational waves, the Lense-Thirring effect, and modern cosmology. A complete understanding of cosmology, from the earliest moments to the ultimate fate of the universe, will require developments in physics beyond Einstein, to a unified theory of gravity and quantum physics.

  12. Microfabrication of hard x-ray lenses

    DEFF Research Database (Denmark)

    Stöhr, Frederik

    This thesis deals with the development of silicon compound refractive lenses (Si-CRLs) for shaping hard x-ray beams. The CRLs are to be fabricated using state of the art microfabrication techniques. The primary goal of the thesis work is to produce Si-CRLs with considerably increased structure...... intense and wider line beams with narrower waists. The thesis starts with a review of alternative x-ray lenses. Si-CRLs are identified as valuable optical components that allow shaping hard x-rays efficiently and creating beam waists that are clearly in the nanometer range. They stand out...... and characterized with respect to their shape. Their optical performances were tested at the European Synchrotron Radiation Facility (ESRF). Two 1D-focusing Si-CRLs suitable as condensers in hard-XRM were developed utilizing the aforementioned two different strategies. The first Si-condenser showed focusing of a 56...

  13. Contact lenses for ophthalmic drug delivery.

    Science.gov (United States)

    Hui, Alex

    2017-09-01

    Contact lenses as a means to deliver pharmaceuticals to the eye have seen a significant increase in research interest in the past few years. This review will detail the in vitro experiments which have investigated use of these contact lenses in the context of the desired pharmacological treatment goals in the management of infectious, inflammatory, allergic and glaucomatous diseases of the eye. The techniques researchers have employed to modify and tailor drug release rates from these materials, including the use of vitamin E diffusion barriers, modified ionicity, molecular imprinting and incorporation of drug reservoirs, will be discussed, as well as their impact on drug release kinetics. Finally, the demonstration of the feasibility of these materials when applied in vivo in animal models as well as in humans with and without disease will be presented and their results discussed relating to their implications for the future of the field. © 2017 Optometry Australia.

  14. Design considerations for liquid crystal contact lenses

    Science.gov (United States)

    Bailey, J.; Kaur, S.; Morgan, P. B.; Gleeson, H. F.; Clamp, J. H.; Jones, J. C.

    2017-12-01

    Switchable liquid crystal contact lenses with electrically controllable focal powers have previously been investigated as an alternative to bifocal contact lenses and spectacles for the correction of presbyopia. The simplest lens design uses a meniscus shaped cavity within the lens to contain the liquid crystal. The design of such a lens is considered in detail, including the nematic alignment and electrodes materials. The organic transparent conductor PEDOT:PSS was used as both electrode and planar alignment. Four different configurations are considered, using both planar and homeotropic orientations with either homogenous or axial alignment. Controllable switching of the focal power was demonstrated for each mode and focal power changes of up to ΔP  =  3.3  ±  0.2 D achieved. Such lens designs offer significant potential for a novel form of correction for this common visual problem.

  15. Irregular Corneas: Improve Visual Function With Scleral Contact Lenses.

    Science.gov (United States)

    de Luis Eguileor, Beatriz; Etxebarria Ecenarro, Jaime; Santamaria Carro, Alaitz; Feijoo Lera, Raquel

    2016-10-20

    To assess visual function in patients with irregular cornea who do not tolerate gas permeable (GP) corneal contact lenses and are fitted with GP scleral contact lenses (Rose K2 XL). In this prospective study, we analyzed 15 eyes of 15 patients who did not tolerate GP corneal contact lenses and were fitted with scleral contact lenses (Rose K2 XL). We assessed visual function using visual acuity and the visual function index (VF-14); we used the VF-14 as an indicator of patient satisfaction. The measurements were taken with the optical correction used before and 1 month after the fitting of the Rose K2 XL contact lenses. We also recorded the number of hours lenses had been worn over the first month. Using Rose K2 XL contact lenses, visual acuity was 0.06±0.07 logMAR. In all cases, visual acuity had improved compared with the measurement before fitting the lenses (0.31±0.18 logMAR; P=0.001). VF-14 scores were 72.74±12.38 before fitting of the scleral lenses, and 89.31±10.87 after 1 month of lens use (P=0.003). Patients used these scleral lenses for 9.33±2.99 comfortable hours of wear. Both visual acuity and VF-14 may improve after fitting Rose K2 XL contact lenses in patients with irregular corneas. In addition, in our patients, these lenses can be worn for a longer period than GP corneal contact lenses.

  16. Gravitational lensing by a Horndeski black hole

    Energy Technology Data Exchange (ETDEWEB)

    Badia, Javier [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Eiroa, Ernesto F. [Instituto de Astronomia y Fisica del Espacio (IAFE, CONICET-UBA), Buenos Aires (Argentina); Universidad de Buenos Aires, Ciudad Universitaria Pabellon I, Departamento de Fisica, Facultad de Ciencias Exactas y Naturales, Buenos Aires (Argentina)

    2017-11-15

    In this article we study gravitational lensing by non-rotating and asymptotically flat black holes in Horndeski theory. By adopting the strong deflection limit, we calculate the deflection angle, from which we obtain the positions and the magnifications of the relativistic images. We compare our results with those corresponding to black holes in General Relativity. We analyze the astrophysical consequences in the case of the nearest supermassive black holes. (orig.)

  17. Gravitational lensing of the SNLS supernovae

    International Nuclear Information System (INIS)

    Kronborg, T.

    2011-01-01

    Type Ia supernovae have become an essential tool of modern observational cosmology. By studying the distance-redshift relation of a large number of supernovae, the nature of dark energy can be unveiled. Distances to Type Ia SNe are however affected by gravitational lensing which can induce systematic effects in the measurement of cosmology. The majority of the supernovae is slightly de-magnified whereas a small fraction is significantly magnified due to the mass distribution along the line of sight. This causes naturally an additional dispersion in the observed magnitudes. There are two different ways to estimate the magnification of a supernova. A first method consists in comparing the supernova luminosity, which is measured to about 15% precision, to the mean SN luminosity at the same redshift. Another estimate can be obtained from predicting the magnification induced by the foreground matter density modeled from the measurements of the luminosity of the galaxies with an initial prior on the mass-luminosity relation of the galaxies. A correlation between these 2 estimates will make it possible to tune the initially used mass-luminosity relation resulting in an independent measurement of the dark matter clustering based on the luminosity of SNe Ia. Evidently, this measurement depends crucially on the detection of this correlation also referred to as the lensing signal. This thesis is dedicated to the measurement of the lensing signal in the SNLS 3-year sample. (author)

  18. Personal radon dosimetry from eyeglass lenses

    Energy Technology Data Exchange (ETDEWEB)

    Fleischer, R.L.; Meyer, N.R.; Hadley, S.A.; MacDonald, J.; Cavallo, A

    2001-07-01

    Eyeglass lenses are commonly composed of allyl-diglycol carbonate (CR-39), an alpha-particle detecting plastic, thus making such lenses personal radon dosemeters. Samples of such lenses have been obtained, etched to reveal that radon and radon progeny alpha tracks can be seen in abundance, and sensitivities have been calibrated in radon chambers as a primary calibration, and with a uranium-based source of alpha particles as a convenient secondary standard. With one exception natural, environmental (fossil) track densities ranged from less than 3,000 to nearly 70,000 per cm{sup 2} for eyeglasses that had been worn for various times from one to nearly five years. Average radon concentrations to which those wearers were exposed are inferred to be in the range 14 to 130 Bq.m{sup -3} (0.4 to 3.5 pCi.l{sup -1}). A protocol for consistent, meaningful readout is derived and used. In the exceptional case the fossil track density was 1,780,000 cm{sup -2}, and the inferred (24 h) average radon concentration was 6500 Bq.m{sup -3} (175 pCi.l{sup -1}) for a worker at an inactive uranium mine that is used for therapy. (author)

  19. Electron lenses for the large hadron collider

    CERN Document Server

    Stancari†, G; Bruce, R; Redaelli, S; Rossi, A; Salvachua Ferrando, B

    2014-01-01

    Electron lenses are pulsed, magnetically confined electron beamswhose current-density profile is shaped to obtain the desired effect on the circulating beam. Electron lenses were used in the Fermilab Tevatron collider for bunch-bybunch compensation of long-range beam-beam tune shifts, for removal of uncaptured particles in the abort gap, for preliminary experiments on head-on beam-beamcompensation, and for the demonstration of halo scrapingwith hollow electron beams. Electron lenses for beam-beam compensation are being commissioned in RHIC at BNL. Within the US LHC Accelerator Research Program and the European HiLumi LHC Design Study, hollow electron beam collimation was studied as an option to complement the collimation system for the LHC upgrades. A conceptual design was recently completed, and the project is moving towards a technical design in 2014–2015 for construction in 2015–2017, if needed, after resuming LHC operations and re-assessing collimation needs and requirements at 6.5 TeV. Because of the...

  20. Automation Enhancement of Multilayer Laue Lenses

    Energy Technology Data Exchange (ETDEWEB)

    Lauer K. R.; Conley R.

    2010-12-01

    X-ray optics fabrication at Brookhaven National Laboratory has been facilitated by a new, state of the art magnetron sputtering physical deposition system. With its nine magnetron sputtering cathodes and substrate carrier that moves on a linear rail via a UHV brushless linear servo motor, the system is capable of accurately depositing the many thousands of layers necessary for multilayer Laue lenses. I have engineered a versatile and automated control program from scratch for the base system and many subsystems. Its main features include a custom scripting language, a fully customizable graphical user interface, wireless and remote control, and a terminal-based interface. This control system has already been successfully used in the creation of many types of x-ray optics, including several thousand layer multilayer Laue lenses.Before reaching the point at which a deposition can be run, stencil-like masks for the sputtering cathodes must be created to ensure the proper distribution of sputtered atoms. Quality of multilayer Laue lenses can also be difficult to measure, given the size of the thin film layers. I employ my knowledge of software and algorithms to further ease these previously painstaking processes with custom programs. Additionally, I will give an overview of an x-ray optic simulator package I helped develop during the summer of 2010. In the interest of keeping my software free and open, I have worked mostly with the multiplatform Python and the PyQt application framework, utilizing C and C++ where necessary.

  1. Bias to CMB lensing reconstruction from temperature anisotropies due to large-scale galaxy motions

    Science.gov (United States)

    Ferraro, Simone; Hill, J. Colin

    2018-01-01

    Gravitational lensing of the cosmic microwave background (CMB) is expected to be amongst the most powerful cosmological tools for ongoing and upcoming CMB experiments. In this work, we investigate a bias to CMB lensing reconstruction from temperature anisotropies due to the kinematic Sunyaev-Zel'dovich (kSZ) effect, that is, the Doppler shift of CMB photons induced by Compton scattering off moving electrons. The kSZ signal yields biases due to both its own intrinsic non-Gaussianity and its nonzero cross-correlation with the CMB lensing field (and other fields that trace the large-scale structure). This kSZ-induced bias affects both the CMB lensing autopower spectrum and its cross-correlation with low-redshift tracers. Furthermore, it cannot be removed by multifrequency foreground separation techniques because the kSZ effect preserves the blackbody spectrum of the CMB. While statistically negligible for current data sets, we show that it will be important for upcoming surveys, and failure to account for it can lead to large biases in constraints on neutrino masses or the properties of dark energy. For a stage 4 CMB experiment, the bias can be as large as ≈15 % or 12% in cross-correlation with LSST galaxy lensing convergence or galaxy overdensity maps, respectively, when the maximum temperature multipole used in the reconstruction is ℓmax=4000 , and about half of that when ℓmax=3000 . Similarly, we find that the CMB lensing autopower spectrum can be biased by up to several percent. These biases are many times larger than the expected statistical errors. We validate our analytical predictions with cosmological simulations and present the first complete estimate of secondary-induced CMB lensing biases. The predicted bias is sensitive to the small-scale gas distribution, which is affected by pressure and feedback mechanisms, thus making removal via "bias-hardened" estimators challenging. Reducing ℓmax can significantly mitigate the bias at the cost of a decrease

  2. Galaxy–Galaxy Weak-lensing Measurements from SDSS. I. Image Processing and Lensing Signals

    International Nuclear Information System (INIS)

    Luo, Wentao; Yang, Xiaohu; Zhang, Jun; Tweed, Dylan; Fu, Liping; Shu, Chenggang; Mo, H. J.; Bosch, Frank C. van den; Li, Ran; Li, Nan; Liu, Xiangkun; Pan, Chuzhong; Wang, Yiran; Radovich, Mario

    2017-01-01

    We present our image processing pipeline that corrects the systematics introduced by the point-spread function (PSF). Using this pipeline, we processed Sloan Digital Sky Survey (SDSS) DR7 imaging data in r band and generated a galaxy catalog containing the shape information. Based on our shape measurements of the galaxy images from SDSS DR7, we extract the galaxy–galaxy (GG) lensing signals around foreground spectroscopic galaxies binned in different luminosities and stellar masses. We estimated the systematics, e.g., selection bias, PSF reconstruction bias, PSF dilution bias, shear responsivity bias, and noise rectification bias, which in total is between −9.1% and 20.8% at 2 σ levels. The overall GG lensing signals we measured are in good agreement with Mandelbaum et al. The reduced χ 2 between the two measurements in different luminosity bins are from 0.43 to 0.83. Larger reduced χ 2 from 0.60 to 1.87 are seen for different stellar mass bins, which is mainly caused by the different stellar mass estimator. The results in this paper with higher signal-to-noise ratio are due to the larger survey area than SDSS DR4, confirming that more luminous/massive galaxies bear stronger GG lensing signals. We divide the foreground galaxies into red/blue and star-forming/quenched subsamples and measure their GG lensing signals. We find that, at a specific stellar mass/luminosity, the red/quenched galaxies have stronger GG lensing signals than their counterparts, especially at large radii. These GG lensing signals can be used to probe the galaxy–halo mass relations and their environmental dependences in the halo occupation or conditional luminosity function framework.

  3. Galaxy–Galaxy Weak-lensing Measurements from SDSS. I. Image Processing and Lensing Signals

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Wentao [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Nandan Road 80, Shanghai 200030 (China); Yang, Xiaohu; Zhang, Jun; Tweed, Dylan [Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213 (United States); Fu, Liping; Shu, Chenggang [Shanghai Key Lab for Astrophysics, Shanghai Normal University, 100 Guilin Road, 200234, Shanghai (China); Mo, H. J. [Department of Astronomy, University of Massachusetts, Amherst, MA 01003-9305 (United States); Bosch, Frank C. van den [Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520-8101 (United States); Li, Ran [Key Laboratory for Computational Astrophysics, Partner Group of the Max Planck Institute for Astrophysics, National Astronomical Observatories, Chinese Academy of Sciences, Beijing, 100012 (China); Li, Nan [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Liu, Xiangkun; Pan, Chuzhong [Department of Astronomy, Peking University, Beijing 100871 (China); Wang, Yiran [Department of Astronomy, University of Illinois at Urbana-Champaign, 1002 W. Green Street, Urbana, IL 61801 (United States); Radovich, Mario, E-mail: walt@shao.ac.cn, E-mail: xyang@sjtu.edu.cn [INAF-Osservatorio Astronomico di Napoli, via Moiariello 16, I-80131 Napoli (Italy)

    2017-02-10

    We present our image processing pipeline that corrects the systematics introduced by the point-spread function (PSF). Using this pipeline, we processed Sloan Digital Sky Survey (SDSS) DR7 imaging data in r band and generated a galaxy catalog containing the shape information. Based on our shape measurements of the galaxy images from SDSS DR7, we extract the galaxy–galaxy (GG) lensing signals around foreground spectroscopic galaxies binned in different luminosities and stellar masses. We estimated the systematics, e.g., selection bias, PSF reconstruction bias, PSF dilution bias, shear responsivity bias, and noise rectification bias, which in total is between −9.1% and 20.8% at 2 σ levels. The overall GG lensing signals we measured are in good agreement with Mandelbaum et al. The reduced χ {sup 2} between the two measurements in different luminosity bins are from 0.43 to 0.83. Larger reduced χ {sup 2} from 0.60 to 1.87 are seen for different stellar mass bins, which is mainly caused by the different stellar mass estimator. The results in this paper with higher signal-to-noise ratio are due to the larger survey area than SDSS DR4, confirming that more luminous/massive galaxies bear stronger GG lensing signals. We divide the foreground galaxies into red/blue and star-forming/quenched subsamples and measure their GG lensing signals. We find that, at a specific stellar mass/luminosity, the red/quenched galaxies have stronger GG lensing signals than their counterparts, especially at large radii. These GG lensing signals can be used to probe the galaxy–halo mass relations and their environmental dependences in the halo occupation or conditional luminosity function framework.

  4. Gravitationally lensed quasars in Gaia: I. Resolving small-separation lenses

    Science.gov (United States)

    Lemon, Cameron A.; Auger, Matthew W.; McMahon, Richard G.; Koposov, Sergey E.

    2017-12-01

    Gaia's exceptional resolution (FWHM ∼ 0.1 arcsec) allows identification and cataloguing of the multiple images of gravitationally lensed quasars. We investigate a sample of 49 known lensed quasars in the Sloan Digital Sky Survey (SDSS) footprint, with image separations less than 2 arcsec, and find that eight are detected with multiple components in the first Gaia data release. In the case of the 41 single Gaia detections, we generally are able to distinguish these lensed quasars from single quasars when comparing Gaia flux and position measurements to those of Pan-STARRS and SDSS. This is because the multiple images of these lensed quasars are typically blended in ground-based imaging and therefore the total flux and a flux-weighted centroid are measured, which can differ significantly from the fluxes and centroids of the individual components detected by Gaia. We compare the fluxes through an empirical fit of Pan-STARRS griz photometry to the wide optical Gaia bandpass values using a sample of isolated quasars. The positional offsets are calculated from a recalibrated astrometric SDSS catalogue. Applying flux and centroid difference criteria to spectroscopically confirmed quasars, we discover four new sub-arcsecond-separation lensed quasar candidates which have two distinct components of similar colour in archival Canada-France-Hawaii Telescope or Hyper Suprime Cam data. Our method based on single Gaia detections can be used to identify the ∼1400 lensed quasars with image separation above 0.5 arcsec, expected to have only one image bright enough to be detected by Gaia.

  5. GALAXY SCALE LENSES IN THE RCS2. I. FIRST CATALOG OF CANDIDATE STRONG LENSES

    International Nuclear Information System (INIS)

    Anguita, T.; Barrientos, L. F.; Gladders, M. D.; Faure, C.; Yee, H. K. C.; Gilbank, D. G.

    2012-01-01

    We present the first galaxy scale lens catalog from the second Red-Sequence Cluster Survey. The catalog contains 60 lensing system candidates comprised of Luminous Red Galaxy (LRG) lenses at 0.2 ∼ 11 [M ☉ h –1 ]) and rich in dark matter (M/L-bar∼ 14 [M ☉ /L ☉,B h]). Even though a slight increasing trend in the mass-to-light ratio is observed from z = 0.2 to z = 0.5, current redshift and light profile measurements do not allow stringent constraints on the mass-to-light ratio evolution of LRGs.

  6. [Current care and maintenance systems for contact lenses].

    Science.gov (United States)

    Lipener, César; Ray, Camila Baracat Mendina

    2008-01-01

    The proper maintenance of contact lenses is crucial for their success and to maintain the continuity of their use. Many patients abandon the use of their lenses due to problems that could be solved with relatively simple treatments. The misuse of lenses, coupled with poor adjustment, contamination, eye disease and environmental factors may increase the number of corneal infections through the proliferation of microorganisms. This article aims to provide contact lens care and maintenance updates.

  7. Plasma lenses for SLAC Final Focus Test facility

    International Nuclear Information System (INIS)

    Betz, D.; Cline, D.; Joshi, C.; Rajagopalan, S.; Rosenzweig, J.; Su, J.J.; Williams, R.; Chen, P.; Gundersen, M.; Katsouleas, T.; Norem, J.

    1991-01-01

    A collaborative group of accelerator and plasma physicists and engineers has formed with an interest in exploring the use of plasma lenses to meet the needs of future colliders. Analytic and computational models of plasma lenses are briefly reviewed and several design examples for the SLAC Final Focus Test Beam are presented. The examples include discrete, thick, and adiabatic lenses. A potential plasma source with desirable lens characteristics is presented

  8. Prospects for weak lensing studies with new radio telescopes

    OpenAIRE

    M. L. Brown

    2012-01-01

    I outline the prospects for performing weak lensing studies with the new generation of radio telescopes that are coming online now and in the future. I include a description of a proposed technique to use polarization observations in radio weak lensing analyses which could prove extremely useful for removing a contaminating signal from intrinsic alignments. Ultimately, the Square Kilometre Array promises to be an exceptional instrument for performing weak lensing studies due to the high resol...

  9. The Value Question in Metaphysics.

    Science.gov (United States)

    Kahane, Guy

    2012-07-01

    Much seems to be at stake in metaphysical questions about, for example, God, free will or morality. One thing that could be at stake is the value of the universe we inhabit-how good or bad it is. We can think of competing philosophical positions as describing possibilities, ways the world might turn out to be, and to which value can be assigned. When, for example, people hope that God exists, or fear that we do not possess free will, they express attitudes towards these possibilities, attitudes that presuppose answers to questions about their comparative value. My aim in this paper is to distinguish these evaluative questions from related questions with which they can be confused, to identify structural constraints on their proper pursuit, and to address objections to their very coherence. Answers to such evaluative questions offer one measure of the importance of philosophical disputes.

  10. The Value Question in Metaphysics

    Science.gov (United States)

    Kahane, Guy

    2012-01-01

    Much seems to be at stake in metaphysical questions about, for example, God, free will or morality. One thing that could be at stake is the value of the universe we inhabit—how good or bad it is. We can think of competing philosophical positions as describing possibilities, ways the world might turn out to be, and to which value can be assigned. When, for example, people hope that God exists, or fear that we do not possess free will, they express attitudes towards these possibilities, attitudes that presuppose answers to questions about their comparative value. My aim in this paper is to distinguish these evaluative questions from related questions with which they can be confused, to identify structural constraints on their proper pursuit, and to address objections to their very coherence. Answers to such evaluative questions offer one measure of the importance of philosophical disputes. PMID:23024399

  11. Weak lensing of the Lyman-alpha forest

    Science.gov (United States)

    Croft, Rupert A. C.; Romeo, Alessandro; Metcalf, R. Benton

    2018-03-01

    The angular positions of quasars are deflected by the gravitational lensing effect of foreground matter. The Lyα forest seen in the spectra of these quasars is therefore also lensed. We propose that the signature of weak gravitional lensing of the Lyα forest could be measured using similar techniques that have been applied to the lensed Cosmic Microwave Background, and which have also been proposed for application to spectral data from 21cm radio telescopes. As with 21cm data, the forest has the advantage of spectral information, potentially yielding many lensed "slices" at different redshifts. We perform an illustrative idealized test, generating a high resolution angular grid of quasars (of order arcminute separation), and lensing the Lyα forest spectra at redshifts z = 2 - 3 using a foreground density field. We find that standard quadratic estimators can be used to reconstruct images of the foreground mass distribution at z ˜ 1. There currently exists a wealth of Lyα forest data from quasar and galaxy spectral surveys, with smaller sightline separations expected in the future. Lyα forest lensing is sensitive to the foreground mass distribution at redshifts intermediate between CMB lensing and galaxy shear, and avoids the difficulties of shape measurement associated with the latter. With further refinement and application of mass reconstruction techniques, weak gravitational lensing of the high redshift Lyα forest may become a useful new cosmological probe.

  12. Using Strong Gravitational Lensing to Identify Fossil Group Progenitors

    Science.gov (United States)

    Johnson, Lucas E.; Irwin, Jimmy A.; White, Raymond E., III; Wong, Ka-Wah; Maksym, W. Peter; Dupke, Renato A.; Miller, Eric D.; Carrasco, Eleazar R.

    2018-04-01

    Fossil galaxy systems are classically thought to be the end result of galaxy group/cluster evolution, as galaxies experiencing dynamical friction sink to the center of the group potential and merge into a single, giant elliptical that dominates the rest of the members in both mass and luminosity. Most fossil systems discovered lie within z fossil criteria within the look forward time. Since strong gravitational lensing preferentially selects groups merging along the line of sight, or systems with a high mass concentration like fossil systems, we searched the CASSOWARY survey of strong-lensing events with the goal of determining whether lensing systems have any predisposition to being fossil systems or progenitors. We find that ∼13% of lensing groups are identified as traditional fossils while only ∼3% of nonlensing control groups are. We also find that ∼23% of lensing systems are traditional fossil progenitors compared to ∼17% for the control sample. Our findings show that strong-lensing systems are more likely to be fossil/pre-fossil systems than comparable nonlensing systems. Cumulative galaxy luminosity functions of the lensing and nonlensing groups also indicate a possible, fundamental difference between strong-lensing and nonlensing systems’ galaxy populations, with lensing systems housing a greater number of bright galaxies even in the outskirts of groups.

  13. Quantitative evaluation of performance of three-dimensional printed lenses

    Science.gov (United States)

    Gawedzinski, John; Pawlowski, Michal E.; Tkaczyk, Tomasz S.

    2017-08-01

    We present an analysis of the shape, surface quality, and imaging capabilities of custom three-dimensional (3-D) printed lenses. 3-D printing technology enables lens prototypes to be fabricated without restrictions on surface geometry. Thus, spherical, aspherical, and rotationally nonsymmetric lenses can be manufactured in an integrated production process. This technique serves as a noteworthy alternative to multistage, labor-intensive, abrasive processes, such as grinding, polishing, and diamond turning. Here, we evaluate the quality of lenses fabricated by Luxexcel using patented Printoptical©; technology that is based on an inkjet printing technique by comparing them to lenses made with traditional glass processing technologies (grinding, polishing, etc.). The surface geometry and roughness of the lenses were evaluated using white-light and Fizeau interferometers. We have compared peak-to-valley wavefront deviation, root mean square (RMS) wavefront error, radii of curvature, and the arithmetic roughness average (Ra) profile of plastic and glass lenses. In addition, the imaging performance of selected pairs of lenses was tested using 1951 USAF resolution target. The results indicate performance of 3-D printed optics that could be manufactured with surface roughness comparable to that of injection molded lenses (Ra<20 nm). The RMS wavefront error of 3-D printed prototypes was at a minimum 18.8 times larger than equivalent glass prototypes for a lens with a 12.7 mm clear aperture, but, when measured within 63% of its clear aperture, the 3-D printed components' RMS wavefront error was comparable to glass lenses.

  14. Reconstructing the lensing mass in the Universe from photometric catalogue data

    NARCIS (Netherlands)

    Collett, Thomas E.; Marshall, Philip J.; Auger, Matthew W.; Hilbert, Stefan; Suyu, Sherry H.; Greene, Zachary; Treu, Tommaso; Fassnacht, Christopher D.; Koopmans, Leon V. E.; Bradac, Marusa; Blandford, Roger D.

    2013-01-01

    High precision cosmological distance measurements towards individual objects such as time delay gravitational lenses or Type Ia supernovae are affected by weak lensing perturbations by galaxies and groups along the line of sight. In time delay gravitational lenses, 'external convergence',

  15. Burning Questions about Calories.

    Science.gov (United States)

    Keller, J. David; Berry, Kimberly A.

    2001-01-01

    Uses questioning techniques to teach about caloric consumption and weight gain. Starts with defining questions about calories and includes the stages of measuring calories, analyzing data, and conducting inquiry research. Includes directions for the experiment. (YDS)

  16. Tevatron Electron Lenses: Design and Operation

    Energy Technology Data Exchange (ETDEWEB)

    Shiltsev, Vladimir; /Fermilab; Bishofberger, Kip; /Los Alamos; Kamerdzhiev, Vsevolod; /Fermilab; Kozub, Sergei; /Serpukhov, IHEP; Kufer, Matthew; Kuznetsov, Gennady; Martinez, Alexander; Olson, Marvin; Pfeffer, Howard; Saewert, Greg; Scarpine, Vic; /Fermilab; Seryi, Andrei; /SLAC; Solyak, Nikolai; /Fermilab; Sytnik, Veniamin; /Serpukhov, IHEP; Tiunov, Mikhail; /Novosibirsk, IYF; Tkachenko, Leonid; /Serpukhov, IHEP; Wildman, David; Wolff, Daniel; Zhang, Xiao-Long; /Fermilab

    2011-09-12

    Fermilab's Tevatron is currently the world's highest energy accelerator in which tightly focused beams of 980 GeV protons and antiprotons collide at two dedicated interaction points (IPs). Both beams share the same beam pipe and magnet aperture and, in order to avoid multiple detrimental head-on collisions, the beams are placed on separated orbits everywhere except the main IPs by using high-voltage (HV) electrostatic separators. The electromagnetic beam-beam interaction at the main IPs together with the long-range interactions between separated beams adversely affect the collider performance, reducing the luminosity integral per store (period of continuous collisions) by 10-30%. Tuning the collider operation for optimal performance becomes more and more cumbersome as the beam intensities and luminosity increase. The long-range effects which (besides being nonlinear) vary from bunch to bunch are particularly hard to mitigate. A comprehensive review of the beam-beam effects in the Tevatron Collider Run II can be found in Ref. [1]. The beam-beam effects have been the dominating sources of beam loss and lifetime limitations in the Tevatron proton-antiproton collider [1]. Electron lenses were originally proposed for compensation of electromagnetic long-range and head-on beam-beam interactions of proton and antiproton beams [2]. Results of successful employment of two electron lenses built and installed in the Tevatron are reported in [3,4,5]. In this paper we present design features of the Tevatron electron lenses (TELs), discuss the generation of electron beams, describe different modes of operation and outline the technical parameters of various subsystems.

  17. Precision cluster mass determination from weak lensing

    Science.gov (United States)

    Mandelbaum, Rachel; Seljak, Uroš; Baldauf, Tobias; Smith, Robert E.

    2010-07-01

    Weak gravitational lensing has been used extensively in the past decade to constrain the masses of galaxy clusters, and is the most promising observational technique for providing the mass calibration necessary for precision cosmology with clusters. There are several challenges in estimating cluster masses, particularly (a) the sensitivity to astrophysical effects and observational systematics that modify the signal relative to the theoretical expectations, and (b) biases that can arise due to assumptions in the mass estimation method, such as the assumed radial profile of the cluster. All of these challenges are more problematic in the inner regions of the cluster, suggesting that their influence would ideally be suppressed for the purpose of mass estimation. However, at any given radius the differential surface density measured by lensing is sensitive to all mass within that radius, and the corrupted signal from the inner parts is spread out to all scales. We develop a new statistic Υ(RR0) that is ideal for estimation of cluster masses because it completely eliminates mass contributions below a chosen scale (which we suggest should be about 20 per cent of the virial radius), and thus reduces sensitivity to systematic and astrophysical effects. We use simulated and analytical profiles including shape noise to quantify systematic biases on the estimated masses for several standard methods of mass estimation, finding that these can lead to significant mass biases that range from 10 to over 50 per cent. The mass uncertainties when using the new statistic Υ(RR0) are reduced by up to a factor of 10 relative to the standard methods, while only moderately increasing the statistical errors. This new method of mass estimation will enable a higher level of precision in future science work with weak lensing mass estimates for galaxy clusters.

  18. The Questions of Curriculum

    Science.gov (United States)

    Dillon, J. T.

    2009-01-01

    What are the basic things that compose curriculum, and what are the questions that may be posed about these things? Joseph Schwab's conception of curriculum is used to introduce a scheme of questions concerning the nature, elements, and practice of curriculum. Formulations of questions by other curriculum theorists are reviewed and analysed in…

  19. Interfacing with questions

    DEFF Research Database (Denmark)

    Soon, Winnie

    2016-01-01

    This article discusses an artistic project entitled If I wrote you a love letter would you write back (and thousands of other questions): a piece of software that utilizes Twitter web API to query questions, drawing unpredictable questions in real-time from the distributed database of Twitter...

  20. Magnified Weak Lensing Cross Correlation Tomography

    Energy Technology Data Exchange (ETDEWEB)

    Ulmer, Melville P., Clowe, Douglas I.

    2010-11-30

    This project carried out a weak lensing tomography (WLT) measurement around rich clusters of galaxies. This project used ground based photometric redshift data combined with HST archived cluster images that provide the WLT and cluster mass modeling. The technique has already produced interesting results (Guennou et al, 2010,Astronomy & Astrophysics Vol 523, page 21, and Clowe et al, 2011 to be submitted). Guennou et al have validated that the necessary accuracy can be achieved with photometric redshifts for our purposes. Clowe et al titled "The DAFT/FADA survey. II. Tomographic weak lensing signal from 10 high redshift clusters," have shown that for the **first time** via this purely geometrical technique, which does not assume a standard rod or candle, that a cosmological constant is **required** for flat cosmologies. The intent of this project is not to produce the best constraint on the value of the dark energy equation of state, w. Rather, this project is to carry out a sustained effort of weak lensing tomography that will naturally feed into the near term Dark Energy Survey (DES) and to provide invaluable mass calibration for that project. These results will greatly advance a key cosmological method which will be applied to the top-rated ground-based project in the Astro2020 decadal survey, LSST. Weak lensing tomography is one of the key science drivers behind LSST. CO-I Clowe is on the weak lensing LSST committee, and senior scientist on this project, at FNAL James Annis, plays a leading role in the DES. This project has built on successful proposals to obtain ground-based imaging for the cluster sample. By 1 Jan, it is anticipated the project will have accumulated complete 5-color photometry on 30 (or about 1/3) of the targeted cluster sample (public webpage for the survey is available at http://cencos.oamp.fr/DAFT/ and has a current summary of the observational status of various clusters). In all, the project has now been awarded the equivalent of over 60

  1. The lensing properties of the Einasto profile

    OpenAIRE

    Retana-Montenegro, E.; Frutos-Alfaro, F.

    2011-01-01

    In recent high resolution N-body CDM simulations, it has been had found that nonsingular three-parameter models, e.g. the Einasto profile has a better performance better than the singular two-parameter models, e.g. the Navarro, Frenk and White in the fitting of a wide range of dark matter halos. A problem with this profile is that the surface mass density is non-analytical for general values of the Einasto index. Therefore, its other lensing properties have the same problem. We obtain an exac...

  2. Realizable planar gradient-index solar lenses.

    Science.gov (United States)

    Kotsidas, Panagiotis; Modi, Vijay; Gordon, Jeffrey M

    2012-04-01

    The design of single element planar hemispherical gradient-index solar lenses that can accommodate the constraints of realistic materials and fabrication techniques are presented, and simulated with an extended and polychromatic solar source for concentrator photovoltaics at flux concentration values exceeding 1000 suns. The planar hemispherical far-field lens is created from a near-field unit magnification spherical gradient-index design, and illustrated with an f/1.40 square solar lens that allows lossless packing within a concentrator module.

  3. Vibrational microspectroscopy analysis of human lenses

    Science.gov (United States)

    Paluszkiewicz, C.; Piergies, N.; Sozańska, A.; Chaniecki, P.; Rękas, M.; Miszczyk, J.; Gajda, M.; Kwiatek, W. M.

    2018-01-01

    In this study we present vibrational analysis of healthy (non-affected by cataract) and cataractous human lenses by means of Raman and FTIR spectroscopy methods. The performed analysis provides complex information about the secondary structure of the proteins and conformational changes of the amino acid residues due to the formation of opacification of human lens. Briefly, the changes in the conformation of the Tyr and Trp residues and the protein secondary structure between the healthy and cataractous samples, were recognized. Moreover, the observed spectral pattern suggests that the process of cataract development does not occur uniformly over the entire volume of the lens.

  4. Electron Beam Generation in Tevatron Electron Lenses

    International Nuclear Information System (INIS)

    Kamerdzhiev, V.; Kuznetsov, G.; Shiltsev, V.; Solyak, N.; Tiunov, M.

    2006-01-01

    New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices

  5. Electron beam generation in Tevatron electron lenses

    International Nuclear Information System (INIS)

    Kamerdzhiev, V.; Kuznetsov, G.; Shiltsev, V.; Solyak, N.; Tiunov, M.

    2006-01-01

    New type of high perveance electron guns with convex cathode has been developed. Three guns described in this article are built to provide transverse electron current density distributions needed for Electron Lenses for beam-beam compensation in the Tevatron collider. The current distribution can be controlled either by the gun geometry or by voltage on a special control electrode located near cathode. We present the designs of the guns and report results of beam measurements on the test bench. Because of their high current density and low transverse temperature of electrons, electron guns of this type can be used in electron cooling and beam-beam compensation devices

  6. From Spheric to Aspheric Solid Polymer Lenses: A Review

    Directory of Open Access Journals (Sweden)

    Kuo-Yung Hung

    2011-01-01

    Full Text Available This paper presents a new approach in the use of MEMS technology to fabricate micro-optofluidic polymer solid lenses in order to achieve the desired profile, focal length, numerical aperture, and spot size. The resulting polymer solid lenses can be applied in optical data storage systems, imaging systems, and automated optical inspection systems. In order to meet the various needs of different applications, polymer solid lenses may have a spherical or aspherical shape. The method of fabricating polymer solid lenses is different from methods used to fabricate tunable lenses with variable focal length or needing an external control system to change the lens geometry. The current trend in polymer solid lenses is toward the fabrication of microlenses with a high numerical aperture, small clear aperture (<2 mm, and high transmittance. In this paper we focus on the use of thermal energy and electrostatic force in shaping the lens profile, including both spherical and aspherical lenses. In addition, the paper discusses how to fabricate a lens with a high numerical aperture of 0.6 using MEMS and also compares the optical characteristics of polymer lens materials, including SU-8, Norland Optical Adhesive (NOA, and cyclic olefin copolymer (COC. Finally, new concepts and applications related to micro-optofluidic lenses and polymer materials are also discussed.

  7. Shallow rainwater lenses in deltaic areas with saline seepage

    NARCIS (Netherlands)

    De Louw, Perry G.B.; Eeman, Sara; Siemon, Bernhard; Voortman, Bernard R.; Gunnink, Jan; Van Baaren, Esther S.; Oude Essink, Gualbert

    2011-01-01

    In deltaic areas with saline seepage, fresh water availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence

  8. Shallow rainwater lenses in deltaic areas with saline seepage

    NARCIS (Netherlands)

    Louw, de P.G.B.; Eeman, S.; Siemon, B.; `Voortman, B.R.; Gunnink, J.; Baaren, E.S.; Oude Essink, G.H.P.

    2011-01-01

    In deltaic areas with saline seepage, freshwater availability is often limited to shallow rainwater lenses lying on top of saline groundwater. Here we describe the characteristics and spatial variability of such lenses in areas with saline seepage and the mechanisms that control their occurrence and

  9. A dearth of dark matter in strong gravitational lenses

    NARCIS (Netherlands)

    Sanders, R. H.

    I show that the lensing masses of the Sloan Lens Advanced Camera Surveys sample of strong gravitational lenses are consistent with the stellar masses determined from population synthesis models using the Salpeter initial mass function. This is true in the context of both General Relativity and

  10. 30 CFR 18.66 - Tests of windows and lenses.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Tests of windows and lenses. 18.66 Section 18... Tests § 18.66 Tests of windows and lenses. (a) Impact tests. A 4-pound cylindrical weight with a 1-inch-diameter hemispherical striking surface shall be dropped (free fall) to strike the window or lens in its...

  11. Gauge-invariant formalism of cosmological weak lensing

    Science.gov (United States)

    Yoo, Jaiyul; Grimm, Nastassia; Mitsou, Ermis; Amara, Adam; Refregier, Alexandre

    2018-04-01

    We present the gauge-invariant formalism of cosmological weak lensing, accounting for all the relativistic effects due to the scalar, vector, and tensor perturbations at the linear order. While the light propagation is fully described by the geodesic equation, the relation of the photon wavevector to the physical quantities requires the specification of the frames, where they are defined. By constructing the local tetrad bases at the observer and the source positions, we clarify the relation of the weak lensing observables such as the convergence, the shear, and the rotation to the physical size and shape defined in the source rest-frame and the observed angle and redshift measured in the observer rest-frame. Compared to the standard lensing formalism, additional relativistic effects contribute to all the lensing observables. We explicitly verify the gauge-invariance of the lensing observables and compare our results to previous work. In particular, we demonstrate that even in the presence of the vector and tensor perturbations, the physical rotation of the lensing observables vanishes at the linear order, while the tetrad basis rotates along the light propagation compared to a FRW coordinate. Though the latter is often used as a probe of primordial gravitational waves, the rotation of the tetrad basis is indeed not a physical observable. We further clarify its relation to the E-B decomposition in weak lensing. Our formalism provides a transparent and comprehensive perspective of cosmological weak lensing.

  12. Biochemical analyses of lipids deposited on silicone hydrogel lenses

    Directory of Open Access Journals (Sweden)

    Shin Hatou

    2010-07-01

    Conclusions: The quantity of total lipid and cholesterol deposited on the 3 silicone hydrogel lenses tested did not differ. However, there were significant differences in the amounts of phospholipid deposited among the 3 silicone hydrogel lenses, of which clinical significance should be explored in the future study.

  13. Hybrid Contact Lenses for Visual Management of Patients after ...

    African Journals Online (AJOL)

    2018-04-04

    Apr 4, 2018 ... contact lenses for visual rehabilitation of postkeratoplasty patients. Materials and Methods: Twenty eyes of ... UCVA was 1.00 logarithm of the minimum angle of resolution (logMAR) which improved to 0.40 logMAR after ..... time as a measure of success of scleral lenses for patients with irregular astigmatism.

  14. Compound Refractive Lenses for Thermal Neutron Applications

    Energy Technology Data Exchange (ETDEWEB)

    Gary, Charles K.

    2013-11-12

    This project designed and built compound refractive lenses (CRLs) that are able to focus, collimate and image using thermal neutrons. Neutrons are difficult to manipulate compared to visible light or even x rays; however, CRLs can provide a powerful tool for focusing, collimating and imaging neutrons. Previous neutron CRLs were limited to long focal lengths, small fields of view and poor resolution due to the materials available and manufacturing techniques. By demonstrating a fabrication method that can produce accurate, small features, we have already dramatically improved the focal length of thermal neutron CRLs, and the manufacture of Fresnel lens CRLs that greatly increases the collection area, and thus efficiency, of neutron CRLs. Unlike a single lens, a compound lens is a row of N lenslets that combine to produce an N-fold increase in the refraction of neutrons. While CRLs can be made from a variety of materials, we have chosen to mold Teflon lenses. Teflon has excellent neutron refraction, yet can be molded into nearly arbitrary shapes. We designed, fabricated and tested Teflon CRLs for neutrons. We demonstrated imaging at wavelengths as short as 1.26 ? with large fields of view and achieved resolution finer than 250 μm which is better than has been previously shown. We have also determined designs for Fresnel CRLs that will greatly improve performance.

  15. Engineering acoustic lenses with help from evolution

    Science.gov (United States)

    Ha˚Kansson, Andreas; Sánchez-Dehesa, José; Sánchis, Lorenzo

    2004-05-01

    Optimization engineering through evolutionary algorithms have proven to be very efficient, especially in hard problems containing a large set of optimization parameters. Like evolution this family of algorithms is able to tackle enormous complex problems with fairly simple means. Here, a simple genetic algorithm [J. H. Holland, Adaptation in Natural and Artificial Systems (Univ. of Michigan, Ann Arbor, 1975)] is used in conjunction with the multiple scattering theory [L. Sánchis et al., Phys. Rev. B 67, 035422 (2003)] to fabricate a new generation of acoustic devices based on a discrete number of cylindrical scatterers. In particular, acoustic lenses [F. Cervera et al., Phys. Rev. Lett. 88, 023902 (2002)] with flat surfaces have been designed to focus the sound in a fixed focal point for one or multiple frequencies. Each scatterer is carefully placed using the optimization method within the preset boundary conditions, to maximize the pressure contribution in the chosen focal spot. With this method acoustic lenses with very low f-numbers of the order 0.3 and with amplifications over 12 dB have been estimated using a reduced number of scatterers (~60). Preliminary results obtained from the experimental realization of the designed devices confirm our predictions.

  16. Probing neutrino masses with CMB lensing extraction

    International Nuclear Information System (INIS)

    Lesgourgues, Julien; Perotto, Laurence; Pastor, Sergio; Piat, Michel

    2006-01-01

    We evaluate the ability of future cosmic microwave background (CMB) experiments to measure the power spectrum of large scale structure using quadratic estimators of the weak lensing deflection field. We calculate the sensitivity of upcoming CMB experiments such as BICEP, QUaD, BRAIN, ClOVER and Planck to the nonzero total neutrino mass M ν indicated by current neutrino oscillation data. We find that these experiments greatly benefit from lensing extraction techniques, improving their one-sigma sensitivity to M ν by a factor of order four. The combination of data from Planck and the SAMPAN mini-satellite project would lead to σ(M ν )∼0.1 eV, while a value as small as σ(M ν )∼0.035 eV is within the reach of a space mission based on bolometers with a passively cooled 3-4 m aperture telescope, representative of the most ambitious projects currently under investigation. We show that our results are robust not only considering possible difficulties in subtracting astrophysical foregrounds from the primary CMB signal but also when the minimal cosmological model (Λ Mixed Dark Matter) is generalized in order to include a possible scalar tilt running, a constant equation-of-state parameter for the dark energy and/or extra relativistic degrees of freedom

  17. Multipolar moments of weak lensing signal around clusters. Weighing filaments in harmonic space

    Science.gov (United States)

    Gouin, C.; Gavazzi, R.; Codis, S.; Pichon, C.; Peirani, S.; Dubois, Y.

    2017-09-01

    Context. Upcoming weak lensing surveys such as Euclid will provide an unprecedented opportunity to quantify the geometry and topology of the cosmic web, in particular in the vicinity of lensing clusters. Aims: Understanding the connectivity of the cosmic web with unbiased mass tracers, such as weak lensing, is of prime importance to probe the underlying cosmology, seek dynamical signatures of dark matter, and quantify environmental effects on galaxy formation. Methods: Mock catalogues of galaxy clusters are extracted from the N-body PLUS simulation. For each cluster, the aperture multipolar moments of the convergence are calculated in two annuli (inside and outside the virial radius). By stacking their modulus, a statistical estimator is built to characterise the angular mass distribution around clusters. The moments are compared to predictions from perturbation theory and spherical collapse. Results: The main weakly chromatic excess of multipolar power on large scales is understood as arising from the contraction of the primordial cosmic web driven by the growing potential well of the cluster. Besides this boost, the quadrupole prevails in the cluster (ellipsoidal) core, while at the outskirts, harmonic distortions are spread on small angular modes, and trace the non-linear sharpening of the filamentary structures. Predictions for the signal amplitude as a function of the cluster-centric distance, mass, and redshift are presented. The prospects of measuring this signal are estimated for current and future lensing data sets. Conclusions: The Euclid mission should provide all the necessary information for studying the cosmic evolution of the connectivity of the cosmic web around lensing clusters using multipolar moments and probing unique signatures of, for example, baryons and warm dark matter.

  18. Natural and anthropogenic factors affecting freshwater lenses in coastal dunes of the Adriatic coast

    Science.gov (United States)

    Cozzolino, Davide; Greggio, Nicolas; Antonellini, Marco; Giambastiani, Beatrice Maria Sole

    2017-08-01

    This study characterizes the near-shore portion of the shallow coastal aquifer included in the Ravenna area (Northern Italy) with special attention to the roles of coastal dunes as freshwater reservoirs and their buffer on groundwater salinity. The paper focuses on the presence and evolution of freshwater lenses below coastal dunes and highlights the existing differences between preserved natural dunes and dunes strongly affected by human intervention. The influence that multiple natural and anthropogenic factors, such as land cover, local drainage network, and beach erosion have on the presence, size and evolution of the freshwater lenses in the aquifer is quantified and discussed. The methodology includes multiple seasonal monitoring and sampling campaigns of physical (water level, salinity, and temperature) and chemical (major cations and anions) groundwater parameters. Results indicate that freshwater lenses, where existing, are limited in thickness (about 1-2 m). Proximity to drainage ditches as well as limited dune elevation and size do not allow the formation and permanent storage of large freshwater lenses in the aquifer below the dunes. The pine forest land cover, that replaced the typical bush or sand cover, intensifies evapotranspiration reducing net infiltration and freshwater storage. The cation species distribution in the water shows that a freshening process is ongoing in preserved natural sites with stable or advancing beaches, whereas a salinization process is ongoing in anthropogenic-impacted areas with strongly-fragmented dune systems. Currently, the thin freshwater lenses in the shallow Ravenna coastal aquifer are limited in space and have no relevance for irrigation or any other human activity. The dune-beach system, however, is the recharge zone of the coastal aquifer and its protection is important to reduce water and soil salinization, which in turn control the health of the whole coastal ecosystem.

  19. Barriers, motivators and enablers for dispensing multifocal contact lenses in Mumbai, India.

    Science.gov (United States)

    Thite, Nilesh; Shah, Ukti; Mehta, Jasmin; Jurkus, Janice

    2015-01-01

    To understand the potential barriers, motivators and enablers in dispensing multifocal contact lenses (MFCL). Two focus group discussions were conducted to design questionnaires regarding the prescribing habits for multifocal contact lenses (MFCL). Questions on potential barriers and motivators were included. The questionnaires were distributed among 133 eye care practitioners across Mumbai, India. Practitioners fitting one or less patient per month with MFCL completed the survey describing potential barriers, while those who prescribed more MFCL's per month completed the survey describing enablers and motivators. Responses from 102 practitioners were received. Most common potential barriers in prescribing MFCL were increased chair time (75%), lack of readily available trials (69%) and limitation in power range (63%). Lack of awareness among patients (90%) was the most common barrier from patients' outlook. Professional satisfaction (88%) and better business proposition (82%) were observed as main motivators while availability of the trials (84%) and correct patient selection (82%) were the major enablers. Graduate Optometrists felt dispensing MFCL did not offer a good business proposition (p=0.02). Experienced practitioners were observed to be least motivated (p=0.01) and believed that their patients found these lenses expensive (p=0.02). To enhance the MFCL practice, barriers like lack of awareness and limitations in power range must be addressed. Trial lens availability may motivate practitioners to prescribe MFCL. Further probing is required to understand lack of motivation among experienced practitioners. Copyright © 2014 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  20. Gravitational lensing of gravitational waves from merging neutron star binaries

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yun; Stebbins, Albert; Turner, Edwin L.

    1996-05-01

    We discuss the gravitational lensing of gravitational waves from merging neutron star binaries, in the context of advanced LIGO type gravitational wave detectors. We consider properties of the expected observational data with cut on the signal-to-noise ratio \\rho, i.e., \\rho>\\rho_0. An advanced LIGO should see unlensed inspiral events with a redshift distribution with cut-off at a redshift z_{\\rm max} < 1 for h \\leq 0.8. Any inspiral events detected at z>z_{\\rm max} should be lensed. We compute the expected total number of events which are present due to gravitational lensing and their redshift distribution for an advanced LIGO in a flat Universe. If the matter fraction in compact lenses is close to 10\\%, an advanced LIGO should see a few strongly lensed events per year with \\rho >5.

  1. [Quality of life in patients wearing scleral lenses].

    Science.gov (United States)

    Picot, C; Gauthier, A-S; Campolmi, N; Delbosc, B

    2015-09-01

    To evaluate the contribution of scleral lenses in terms of improving the quality of life in the treatment of astigmatism after penetrating keratoplasty or in keratoconus. We conducted an observational retrospective study, evaluating quality of life (QOL) of patients who failed to adapt to RPG lenses, fitted with SPOT(®) scleral lenses between October 2007 and March 2011 in the University Hospital of Besançon Department of Ophthalmology. QOL was assessed before and after scleral lens adaptation with the French version of the National Eye Institute Visual Function Questionnaire 25 (NEI-VFQ 25). We included 47 patients (83 eyes) fitted with scleral lenses on one or both eyes: 56 eyes with keratoconus and 27 post-keratoplasty eyes. The average duration of wearing scleral lenses was 18±10months and the average wearing time was 14±3hours per day. The rate of participation in the survey was 86.5% (41 patients). Visual acuity in the better eye progressed from 0.68±0.46 to 0.15±0.17 logMAR at the 6th month after scleral lens adaptation (Pscleral lenses for at least 6 months were significantly higher than those without scleral lenses, with a global score of 80.2/100 with, versus 48.1/100 without, scleral lenses (P0.05). Scleral lenses showed a significant improvement in quality of life for patients who had failed or are intolerant to conventional rigid gas permeable contact lenses. In our two main optical indications, keratoconus and keratoplasty, they represent an alternative or a step prior to surgery. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

  2. Power spectrum of dark matter substructure in strong gravitational lenses

    Science.gov (United States)

    Diaz Rivero, Ana; Cyr-Racine, Francis-Yan; Dvorkin, Cora

    2018-01-01

    Studying the smallest self-bound dark matter structure in our Universe can yield important clues about the fundamental particle nature of dark matter. Galaxy-scale strong gravitational lensing provides a unique way to detect and characterize dark matter substructures at cosmological distances from the Milky Way. Within the cold dark matter (CDM) paradigm, the number of low-mass subhalos within lens galaxies is expected to be large, implying that their contribution to the lensing convergence field is approximately Gaussian and could thus be described by their power spectrum. We develop here a general formalism to compute from first principles the substructure convergence power spectrum for different populations of dark matter subhalos. As an example, we apply our framework to two distinct subhalo populations: a truncated Navarro-Frenk-White subhalo population motivated by standard CDM, and a truncated cored subhalo population motivated by self-interacting dark matter (SIDM). We study in detail how the subhalo abundance, mass function, internal density profile, and concentration affect the amplitude and shape of the substructure power spectrum. We determine that the power spectrum is mostly sensitive to a specific combination of the subhalo abundance and moments of the mass function, as well as to the average tidal truncation scale of the largest subhalos included in the analysis. Interestingly, we show that the asymptotic slope of the substructure power spectrum at large wave number reflects the internal density profile of the subhalos. In particular, the SIDM power spectrum exhibits a characteristic steepening at large wave number absent in the CDM power spectrum, opening the possibility of using this observable, if at all measurable, to discern between these two scenarios.

  3. Asking the Right Questions

    DEFF Research Database (Denmark)

    Richter, Line

    Based on fieldwork in Mali this paper discusses the role of anthropology (and the anthropologist) in a large public health research project on children's health. In the uncertainty and disquiet that comes with the battle to combat and avoid diseases in a setting where poverty and abysmal diseases......, is the ability to move beyond even the best hidden assumptions and question our own questions, thereby enabling us to ask the right questions....

  4. Live your questions now

    OpenAIRE

    Brownrigg, Jenny

    2016-01-01

    'Live Your Questions Now' is a case study for Cubitt Education's publication 'Aging in Public: creative practice in ageing and the public realm from across the UK', edited by Daniel Baker and published by Cubitt Gallery, Studios and Education, London in 2016. The publication was linked to Cubitt's programme 'Public Wisdom' (2011-2015). My case study is about 'Live your questions now', a group exhibition I curated in 2011 for Mackintosh Museum, The Glasgow School of Art. 'Live your questions n...

  5. Question Classification Taxonomies as Guides to Formulating Questions for Use in Chemistry Classrooms

    Science.gov (United States)

    Festo, Kayima

    2016-01-01

    Teacher questions play an important role in facilitating classroom discourse. Using appropriate question types and proper questioning techniques help to create reflective-active learners. Teacher questions can elicit students' explanations, elaboration of their ideas and thinking, and they can be used to disclose students' misconceptions. Despite…

  6. Investigation of the Degree of Disorder of the Structure of Polymer Soft Contact Lenses Using Positron Annihilation Lifetime Spectroscopy PALS.

    Science.gov (United States)

    Filipecki, Jacek; Kotynia, Katarzyna; Filipecka, Katarzyna

    2016-01-01

    Hydrogel and silicone-hydrogel polymeric materials are widely used in ophthalmology for the manufacture of contact lenses. An important aspect is the investigation of the structure of these materials. This study has been conducted in order to compare the degree of disorder and presence of free volumes in the internal structure of the polymeric soft contact lenses Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel). Differences in the occurrence of trapping centers for positrons and free volumes between the types of investigated contact lenses have been demonstrated. Two types of polymeric contact lenses were used as materials: Omafilcon A (hydrogel) and Comfilcon A (silicone-hydrogel). The study was performed using positron annihilation lifetime spectroscopy (PALS). When the results of the measurements has been obtained, a graphical curve has created to describe the relationship of the number of annihilation acts in time. Significant changes were observed between the contact lenses investigated in positron trapping in macropores (based on a two-state model) and the presence of free volumes (based on the Tao-Eldrup model). The use of the positron annihilation two-state model made it possible to demonstrate that a higher positron trapping rate in macropores occurs in the silicone-hydrogel contact lens. Additionally, calculations using the Tao-Eldrup model show the existence of free volumes in both types of materials. The size and fraction of free volumes is much larger in the silicone-hydrogel contact lens.

  7. A simple technique of intraocular lenses explantation for single-piece foldable lenses

    Directory of Open Access Journals (Sweden)

    Arup Bhaumik

    2017-01-01

    Full Text Available Foldable intraocular lenses (IOLs are most commonly used in modern-day cataract surgery. Explantation of these IOLs is not frequently encountered, but sometimes extreme situations may demand the same. Commonly explantation is achieved by bisecting the IOL inside the anterior chamber with a cutter and delivering the pieces out one by one. This may require corneal wound extension with associated damage and endothelial loss leading to visual deterioration. We devised a simple, innovative IOL explantation technique utilizing a modified Alcon A cartridge and snare. This can successfully refold the IOL to be explanted inside the eye and deliver it out through the same wound. The device has limitations with very thick optic lenses, multipiece, and silicon IOLs. In conclusion, we describe a simple, innovative, and reproducible technique to explant almost any single piece IOL without compromising the original surgery and yielding very satisfactory outcomes.

  8. Legal Philosophy - Five Questions

    DEFF Research Database (Denmark)

    This collection gathers together a host of the most eminent contemporary legal philosophers, who writes about their take on legal philosophy, its fundamental questions and potential.......This collection gathers together a host of the most eminent contemporary legal philosophers, who writes about their take on legal philosophy, its fundamental questions and potential....

  9. Epistemology: 5 Questions

    DEFF Research Database (Denmark)

    Epistemology: 5 Questions is a collection of short interviews based on 5 questions presented to some of the most influential and prominent scholars in epistemology. We hear their views on epistemology with particular emphasis on the intersection between mainstream and formal approaches to the field......; the aim, scope, the future direction of epistemology and how their work fits in these respects...

  10. Exam Question Exchange.

    Science.gov (United States)

    Alexander, John J., Ed.

    1988-01-01

    Describes three examination questions which could be used in college chemistry courses. Discusses each problem and gives acceptable solutions. Problems include: "A Multi-Topic Problem for General Chemistry"; "Consumption of Air by Biuret Reagent--a Question Involving Experimental Design"; and "An Instructive Problem in Heterogeneous Equilibrium."…

  11. Probation, 12 essential questions

    NARCIS (Netherlands)

    Fergus McNeill; Rene Butter; Ioan Durnescu

    2016-01-01

    This volume poses a series of key questions about the practice of probation as an integral part of the European criminal justice system. The contributors are established experts in their respective fields of study and together their questions address the legitimacy, and perhaps continued existence,

  12. GALAXY SCALE LENSES IN THE RCS2. I. FIRST CATALOG OF CANDIDATE STRONG LENSES

    Energy Technology Data Exchange (ETDEWEB)

    Anguita, T. [Centro de Astro-Ingenieria, Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago (Chile); Barrientos, L. F. [Departamento de Astronomia y Astrofisica, Pontificia Universidad Catolica de Chile, Casilla 306, Santiago (Chile); Gladders, M. D. [Department of Astronomy and Astrophysics, University of Chicago, 5640 S. Ellis Avenue, Chicago, IL 60637 (United States); Faure, C. [Laboratoire d' Astrophysique, Ecole Polytechnique Federale de Lausanne (EPFL), Obervatoire de Sauverny, CH-1290 Versoix (Switzerland); Yee, H. K. C.; Gilbank, D. G. [Department of Astronomy and Astrophysics, University of Toronto, 50 St George Street, Toronto, Ontario, M5S 3H4 (Canada)

    2012-04-01

    We present the first galaxy scale lens catalog from the second Red-Sequence Cluster Survey. The catalog contains 60 lensing system candidates comprised of Luminous Red Galaxy (LRG) lenses at 0.2 {approx}< z {approx}< 0.5 surrounded by blue arcs or apparent multiple images of background sources. The catalog is a valuable complement to previous galaxy-galaxy lens catalogs as it samples an intermediate lens redshift range and is composed of bright sources and lenses that allow easy follow-up for detailed analysis. Mass and mass-to-light ratio estimates reveal that the lens galaxies are massive ( M-bar {approx} 5.5 Multiplication-Sign 10{sup 11} [M{sub Sun} h{sup -1}]) and rich in dark matter (M/L-bar{approx} 14 [M{sub Sun }/L{sub Sun ,B} h]). Even though a slight increasing trend in the mass-to-light ratio is observed from z = 0.2 to z = 0.5, current redshift and light profile measurements do not allow stringent constraints on the mass-to-light ratio evolution of LRGs.

  13. Lensing and dynamics in two simple steps

    Science.gov (United States)

    Agnello, A.; Auger, M. W.; Evans, N. W.

    2013-02-01

    We present a ready-to-use method to constrain the density distribution in spherically symmetric early-type galaxy lenses. Assuming a power-law density profile, then joint use of the virial theorem and the lens equation yields simple formulae for the power-law index (or logarithmic density gradient). Any dependence on orbital anisotropy can be tightly constrained or even erased completely. Our results rely just on surface brightnesses and line-of-sight kinematics, making deprojection unnecessary. We revisit three systems that have already been examined in the literature (the Cosmic Horseshoe, the Jackpot and B1608+656) and provide our estimates. Finally, we show that the method yields a good approximation for the density profile even when the true profile is a broken power law, albeit with a mild bias towards isothermality.

  14. A study of chromium in human cataractous lenses and whole blood of diabetics, senile, and normal population.

    Science.gov (United States)

    Pineau, A; Guillard, O; Risse, J F

    1992-01-01

    Chromium (Cr) is of known biological importance, necessary for the maintenance of normal glucose metabolism. There is a lower level of blood Cr concentrations in cases of diabetes. Diabetes carries a risk of cataract development, so the potential effects of Cr on the eye may need to be studied in more depth. The presence of this trace element in both normal and cataractous human lenses has to our knowledge not been investigated so far. The concentration of total Cr in 61 human lenses and 38 blood samples was determined by electrothermal atomic absorption spectrometry with Zeeman effect (EAASZ). Analysis of the levels of Cr in human lenses shows a significant difference between normal and diabetic populations, and an absence of difference between senile and diabetic populations.

  15. Modeling spatial variability of sand-lenses in clay till settings using transition probability and multiple-point geostatistics

    DEFF Research Database (Denmark)

    Kessler, Timo Christian; Nilsson, Bertel; Klint, Knud Erik

    2010-01-01

    of sand-lenses in clay till. Sand-lenses mainly account for horizontal transport and are prioritised in this study. Based on field observations, the distribution has been modeled using two different geostatistical approaches. One method uses a Markov chain model calculating the transition probabilities......The construction of detailed geological models for heterogeneous settings such as clay till is important to describe transport processes, particularly with regard to potential contamination pathways. In low-permeability clay matrices transport is controlled by diffusion, but fractures and sand......-lenses facilitate local advective flow. In glacial settings these geological features occur at diverse extent, geometry, degree of deformation, and spatial distribution. The high level of heterogeneity requires extensive data collection, respectively detailed geological mapping. However, when characterising...

  16. Weak lensing galaxy cluster field reconstruction

    Science.gov (United States)

    Jullo, E.; Pires, S.; Jauzac, M.; Kneib, J.-P.

    2014-02-01

    In this paper, we compare three methods to reconstruct galaxy cluster density fields with weak lensing data. The first method called FLens integrates an inpainting concept to invert the shear field with possible gaps, and a multi-scale entropy denoising procedure to remove the noise contained in the final reconstruction, that arises mostly from the random intrinsic shape of the galaxies. The second and third methods are based on a model of the density field made of a multi-scale grid of radial basis functions. In one case, the model parameters are computed with a linear inversion involving a singular value decomposition (SVD). In the other case, the model parameters are estimated using a Bayesian Monte Carlo Markov Chain optimization implemented in the lensing software LENSTOOL. Methods are compared on simulated data with varying galaxy density fields. We pay particular attention to the errors estimated with resampling. We find the multi-scale grid model optimized with Monte Carlo Markov Chain to provide the best results, but at high computational cost, especially when considering resampling. The SVD method is much faster but yields noisy maps, although this can be mitigated with resampling. The FLens method is a good compromise with fast computation, high signal-to-noise ratio reconstruction, but lower resolution maps. All three methods are applied to the MACS J0717+3745 galaxy cluster field, and reveal the filamentary structure discovered in Jauzac et al. We conclude that sensitive priors can help to get high signal-to-noise ratio, and unbiased reconstructions.

  17. Fitting miniscleral contact lenses in Korean patients with keratoconus.

    Science.gov (United States)

    Kim, Sujin; Lee, Jong Soo; Park, Young Kee; Lee, Seung Uk; Park, Young Min; Lee, Jong Heon; Lee, Ji-Eun

    2017-07-01

    The aim was to evaluate the clinical results of fitting MSD miniscleral contact lenses (MSD; Happy Vision Corp, Anyang, Korea) in Korean patients with keratoconus. This report presents a retrospective case review of 38 keratoconic patients fitted with MSD lenses. Visual acuity, comfort, mean wear time, final lens parameters, relationships between sagittal depth and topographic indices, success rate with the first lens ordered and adverse events were documented. The mean logMAR visual acuity was improved from 0.85 ± 0.78 with glasses and 0.28 ± 0.29 with corneal rigid gas-permeable lenses to 0.10 ± 0.11 with miniscleral contact lenses. Ninety-seven per cent of patients found the miniscleral contact lenses to be comfortable and the mean daily wear time was 10.1 ± 2.3 hours. The mean sagittal depth was 4.70 ± 0.35 mm and there was no correlation between sagittal depth and topographic indices. An average of 3.4 trial lenses was needed to decide the ordered lens and 1.3 ordered lenses to achieve the optimal fitting. One patient discontinued the wear of the lenses after three months due to discomfort. The use of MSD miniscleral contact lenses is a good alternative for patients with keratoconus and for those who failed to respond to other types of lens rehabilitation that results in both successful visual outcome and comfort. © 2016 Optometry Australia.

  18. Effects of refrigeration on daily microbial bioburden of hydrogel lenses.

    Science.gov (United States)

    Lapple, W J; Snyder, A C; Tuovinen, O H

    1987-03-01

    Microbial bioburden of contact lenses was evaluated in connection with lens care by refrigeration. Subjects wore new hydrogel contact lenses for approximately 8 hours. The microbial bioburden initially and after an overnight refrigeration of the lens was evaluated with the use of viable counts on three different media. No major changes in viable counts were observed resulting from this method of storage. Scanning electron microscopy indicated the presence of foreign material on both new and worn lenses, presumed to be debris from lens manufacture and mucoid deposits from daily wear. Microbial colonization was not apparent and single bacterial cells could not be discerned on the micrographs.

  19. Role of mini-scleral gas-permeable lenses in the treatment of corneal disorders.

    Science.gov (United States)

    Ye, Ping; Sun, Amy; Weissman, Barry A

    2007-03-01

    Case report on the clinical implications of mini-scleral gas-permeable contact lenses in the treatment of corneal disorders. Three patients with different corneal disorders were fitted with Jupiter design mini-scleral gas-permeable contact lenses. All three patients achieved excellent vision and comfort. The contact lenses were tolerated well, and no complications were observed. Mini-scleral gas-permeable contact lenses provide a good option for patients who require gas-permeable contact lenses for optimal visual function but do not tolerate corneal contact lenses. Mini-scleral lenses are also an excellent therapeutic tool in the treatment of at least some forms of severe dry eyes.

  20. Therapeutic use of mini-scleral lenses in a patient with Graves’ ophthalmopathy

    Science.gov (United States)

    Harthan, Jennifer S.

    2013-01-01

    Patients with Graves’ ophthalmopathy can be very challenging to manage secondary to the complex nature of their disease presentation. Patients may present with a variety of ocular findings including: lid retraction, periorbital and lid swelling, chemosis, conjunctival hyperemia, proptosis, optic neuropathy, restrictive myopathy, exposure keratopathy and/or keratoconjunctivitis sicca. Mini-scleral and scleral lens designs have been important in the management of irregular and regular corneas, and in the therapy of ocular surface diseases. We present here the case of a 48-year-old Caucasian male who had been diagnosed with Graves’ ophthalmopathy 13 years earlier. With significant ocular surface staining and over ten diopters of astigmatism, the patient had never been able to wear contact lenses comfortably. After being fit with the Mini-Scleral Design™ lenses, his vision improved to 20/25 OU, his ocular surface improved, and overall quality of vision increased. PMID:24646903

  1. Cosmetic Procedure Questions

    Science.gov (United States)

    ... for Every Season How to Choose the Best Skin Care Products In This Section Dermatologic Surgery What is dermatologic ... for Every Season How to Choose the Best Skin Care Products Cosmetic Procedure Questions Want to look younger? Start ...

  2. CAT questions and answers

    International Nuclear Information System (INIS)

    1993-02-01

    This document, prepared in February 1993, addresses the most common questions asked by APS Collaborative Access Teams (CATs). The answers represent the best judgment on the part of the APS at this time. In some cases, details are provided in separate documents to be supplied by the APS. Some of the answers are brief because details are not yet available. The questions are separated into five categories representing different aspects of CAT interactions with the APS: (1) Memorandum of Understanding (MOU), (2) CAT Beamline Review and Construction, (3) CAT Beamline Safety, (4) CAT Beamline Operations, and (5) Miscellaneous. The APS plans to generate similar documents as needed to both address new questions and clarify answers to present questions

  3. Rabies: Questions and Answers

    Science.gov (United States)

    Rabies: Questions and Answers Information about the disease and vaccines What causes rabies? Rabies is caused by a virus. The virus invades ... nervous system and disrupts its functioning. How does rabies spread? The rabies virus is transmitted in the ...

  4. Tetanus: Questions and Answers

    Science.gov (United States)

    Tetanus: Questions and Answers Information about the disease and vaccines What causes tetanus? Tetanus is caused by a toxin (poison) produced by ... to heat and many chemical agents. How does tetanus spread? C. tetani spores can be found in ...

  5. Pertussis Frequently Asked Questions

    Science.gov (United States)

    ... IAC) Parents of Kids with Infectious Diseases (PKIDs) Pertussis Frequently Asked Questions Language: English (US) Español (Spanish) ... frecuentes sobre la tosferina Q: Can vaccines prevent pertussis? A: Yes. Vaccines can prevent pertussis, or whooping ...

  6. Repetitive Questioning II

    Directory of Open Access Journals (Sweden)

    R. C. Hamdy MD

    2018-02-01

    Full Text Available Repetitive questioning is a major problem for caregivers, particularly taxing if they are unable to recognize and understand the reasons why their loved one keeps asking the same question over and over again. Caregivers may be tempted to believe that the patient does not even try to remember the answer given or is just getting obnoxious. This is incorrect. Repetitive questioning is due to the underlying disease: The patient’s short term memory is impaired and he is unable to register, encode, retain and retrieve the answer. If he is concerned about a particular topic, he will keep asking the same question over and over again. To the patient each time she asks the question, it is as if she asked it for the first time. Just answering repetitive questioning by providing repeatedly the same answer is not sufficient. Caregivers should try to identify the underlying cause for this repetitive questioning. In an earlier case study, the patient was concerned about her and her family’s safety and kept asking whether the doors are locked. In this present case study, the patient does not know how to handle the awkward situation he finds himself in. He just does not know what to do. He is not able to adjust to the new unexpected situation. So he repeatedly wants to reassure himself that he is not intruding by asking the same question over and over again. We discuss how the patient’s son-in-law could have avoided this situation and averted the catastrophic ending.

  7. Interesting Questions in Freakonomics

    OpenAIRE

    John DiNardo

    2007-01-01

    Freakonomics is more about "entertainment" than it is a serious attempt at popularization. Consequently, rather than conduct a comprehensive fact check, I use the book as a springboard for a broader inquiry into social science research and take issue with the book's surprising premise that "Economics is a science with excellent tools for gaining answers but a serious shortage of interesting questions." Using examples from Freakonomics , I argue that some of the questions the book addresses ar...

  8. Panspermia asks new questions

    Science.gov (United States)

    Klyce, Brig

    2001-08-01

    There is a widespread sentiment that panspermia is uninteresting is because it does not answer fundamental questions about the origin of life. The strongest version of panspermia asks entirely new questions. While barriers to the acceptance of panspermia are falling and evidence supporting it is accumulating, the mere possibility of panspermia unhinges the Darwinian account of evolutionary progress. The new theory removes an issue dividing science and religion, but it requires an amendment to the big bang theory.

  9. Adjustable adaptive compact fluidic phoropter with no mechanical translation of lenses

    OpenAIRE

    Marks, Randall; Mathine, David L.; Peyman, Gholam; Schwiegerling, Jim; Peyghambarian, N.

    2010-01-01

    We demonstrate a compact optical phoroptor consisting of adjustable astigmatic and defocus lenses. The lenses are fluidically controlled and allow for an arbitrary refractive error to be corrected without mechanically moving lenses. Shack–Hartmann measurements were used to characterize the optical properties of the individual lenses. The lenses were then assembled into the phoropter and controlled with three separate fluid controls. The phoroptor was verified by correcting the vision of a mod...

  10. Sustaining anti-littering behavior within coastal and marine environments: Through the macro-micro level lenses.

    Science.gov (United States)

    Beeharry, Yashna Devi; Bekaroo, Girish; Bokhoree, Chandradeo; Phillips, Michael Robert; Jory, Neelakshi

    2017-06-30

    Being regarded as a problem of global dimensions, marine litter has been a growing concern that affects human beings, wildlife and the economic health of coastal communities to varying degrees. Due to its involvement with human behavior, marine littering has been regarded as a cultural matter encompassing macro and micro level aspects. At the micro or individual level, behavior and behavioral motivation of an individual are driven by perception of that person while at the macro or societal level, aspects including policies and legislations influence behavior. This paper investigates marine littering through the macro-micro level lenses in order to analyze and recommend how anti-littering behavior can be improved and sustained. Using Coleman's model of micro-macro relations, research questions are formulated and investigated through a social survey. Results showed important differences in perceptions among participating groups and to address key issues, potential actions are proposed along with a framework to sustain anti-littering behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. What To Know If Your Child Wants Contact Lenses

    Science.gov (United States)

    ... and wearing decorative lenses purchased from flea markets, beauty supply stores, the Internet and other sources. These ... State & Local Officials Consumers Health Professionals Science & Research Industry Scroll back to top Popular Content Home Latest ...

  12. Fluidic astigmatic and spherical lenses for ophthalmic applications

    Science.gov (United States)

    Marks, Randall Lee

    Fluidic lenses have been developed for ophthalmic applications. The lenses use a pressure differential to deform a membrane, which separates two fluids with different indexes of refraction. The change in membrane shape creates changes in the optical wavefront. By utilizing different boundary conditions on the membrane, the progression of the membrane shape can be controlled. Specifically, a circular restraint is used to produce optical power, whereas a rectangular restraint is used to produce a combination of power and astigmatism. These lenses are analyzed for dominant properties and wavefront quality. By combining 2 rectangular restraint lenses at 45° and a circular restraint lens, both orthogonal second order Zernike astigmatisms as well as second order power can be independently controlled. This combination can also be described as independent control of ophthalmic cylinder, cylinder axis, and power, which is required to create a basic phoropter. A fluidic phoropter is demonstrated and analyzed in this manuscript.

  13. Transparent nanostructured photochromic UV-blocking soft contact lenses.

    Science.gov (United States)

    Pek, Y Shona; Wu, Hong; Chow, Edwin Py; Ying, Jackie Y

    2016-06-01

    We aim to develop transparent UV-blocking photochromic soft contact lenses via polymerization of a bicontinuous nanoemulsion. Transparent nanostructured polymers were prepared by incorporating a polymerizable surfactant and thermal initiator together with water, monomers, UV blockers and photochromic dyes. The polymers were characterized using oxygen permeometer, tensile tester, electron microscope, UV spectrophotometer, corneal cell culture and testing in rabbits. The polymers have good oxygen permeability, water content, stiffness, strength and UV-blocking ability comparable to commercial UV-blocking soft contact lenses. Their response to UV light is comparable to photochromic spectacle lenses, particularly in reverse transition from colored to colorless state. They are nontoxic and nonleaching. Our photochromic UV-blocking contact lenses provide a novel alternative to photochromic spectacles.

  14. [Unusual complications after wearing hard and soft contact lenses].

    Science.gov (United States)

    Roth, H W; Teuchert, J

    1990-01-01

    In a clinical long-term study over a period of 10 years with 3850 patients wearing hard and soft contact lenses, unusual reactions of the cornea and perilimbal conjunctiva have been observed in 3% of all cases. Mainly corneal abrasions, cracks, clouds and mosaics have been observed, which were analyzed as being rare contact lens complications. The causes were lack of proper maintenance of the contact lenses, such as mistakes in cleaning and disinfecting the lenses, mishandling or toxic and allergic reactions due to cleaning and disinfection solutions. Only exact ophthalmological monitoring of the anterior parts of the eye and laboratory tests on the worn lenses permit differentiation between primary eye diseases and contact lens-induced complications.

  15. Adaptive silicone-membrane lenses: planar vs. shaped membrane

    CSIR Research Space (South Africa)

    Schneider, F

    2009-08-01

    Full Text Available In this paper the authors compare the performance and optical quality of two types of adaptive fluidic silicone-membrane lenses. The membranes feature either a homogeneous thickness, or it is shaped resulting in an inhomogeneous cross...

  16. Halloween Safety: Costumes, Candy, and Colored Contact Lenses

    Science.gov (United States)

    ... Products For Consumers Home For Consumers Consumer Updates Halloween Safety: Costumes, Candy, and Colored Contact Lenses Share ... can cause injuries that haunt you long after Halloween. Enjoy a safe and happy Halloween by following ...

  17. Gravitational lensing by a smoothly variable surface mass density

    Science.gov (United States)

    Paczynski, Bohdan; Wambsganss, Joachim

    1989-01-01

    The statistical properties of gravitational lensing due to smooth but nonuniform distributions of matter are considered. It is found that a majority of triple images had a parity characteristic for 'shear-induced' lensing. Almost all cases of triple or multiple imaging were associated with large surface density enhancements, and lensing objects were present between the images. Thus, the observed gravitational lens candidates for which no lensing object has been detected between the images are unlikely to be a result of asymmetric distribution of mass external to the image circle. In a model with smoothly variable surface mass density, moderately and highly amplified images tended to be single rather than multiple. An opposite trend was found in models which had singularities in the surface mass distribution.

  18. Lensing of 21-cm fluctuations by primordial gravitational waves.

    Science.gov (United States)

    Book, Laura; Kamionkowski, Marc; Schmidt, Fabian

    2012-05-25

    Weak-gravitational-lensing distortions to the intensity pattern of 21-cm radiation from the dark ages can be decomposed geometrically into curl and curl-free components. Lensing by primordial gravitational waves induces a curl component, while the contribution from lensing by density fluctuations is strongly suppressed. Angular fluctuations in the 21-cm background extend to very small angular scales, and measurements at different frequencies probe different shells in redshift space. There is thus a huge trove of information with which to reconstruct the curl component of the lensing field, allowing tensor-to-scalar ratios conceivably as small as r~10(-9)-far smaller than those currently accessible-to be probed.

  19. The Danger of Using Tap Water with Contact Lenses

    Science.gov (United States)

    Acanthamoeba is a microbe that is very common in tap water. It has two forms: the trophozoite and the cyst. These trophozoites and cysts can stick to the surface of your contact lenses and then infect your eye.

  20. Clinical Study of Focus NIGHT &DAY® contact lenses | Aldebasi ...

    African Journals Online (AJOL)

    wear contact lenses for up to 3 weeks without ocular complications. Visual acuity, tear functions or corneal structure are not altered. Keywords: optometry, silicone hydrogel materials, resolution, ocular. Sudan Journal of Medical Sciences Vol.

  1. Exploring cosmic origins with CORE: Gravitational lensing of the CMB

    Science.gov (United States)

    Challinor, A.; Allison, R.; Carron, J.; Errard, J.; Feeney, S.; Kitching, T.; Lesgourgues, J.; Lewis, A.; Zubeldía, Í.; Achucarro, A.; Ade, P.; Ashdown, M.; Ballardini, M.; Banday, A. J.; Banerji, R.; Bartlett, J.; Bartolo, N.; Basak, S.; Baumann, D.; Bersanelli, M.; Bonaldi, A.; Bonato, M.; Borrill, J.; Bouchet, F.; Boulanger, F.; Brinckmann, T.; Bucher, M.; Burigana, C.; Buzzelli, A.; Cai, Z.-Y.; Calvo, M.; Carvalho, C.-S.; Castellano, G.; Chluba, J.; Clesse, S.; Colantoni, I.; Coppolecchia, A.; Crook, M.; d'Alessandro, G.; de Bernardis, P.; de Gasperis, G.; De Zotti, G.; Delabrouille, J.; Di Valentino, E.; Diego, J.-M.; Fernandez-Cobos, R.; Ferraro, S.; Finelli, F.; Forastieri, F.; Galli, S.; Genova-Santos, R.; Gerbino, M.; González-Nuevo, J.; Grandis, S.; Greenslade, J.; Hagstotz, S.; Hanany, S.; Handley, W.; Hernandez-Monteagudo, C.; Hervías-Caimapo, C.; Hills, M.; Hivon, E.; Kiiveri, K.; Kisner, T.; Kunz, M.; Kurki-Suonio, H.; Lamagna, L.; Lasenby, A.; Lattanzi, M.; Liguori, M.; Lindholm, V.; López-Caniego, M.; Luzzi, G.; Maffei, B.; Martinez-González, E.; Martins, C. J. A. P.; Masi, S.; Matarrese, S.; McCarthy, D.; Melchiorri, A.; Melin, J.-B.; Molinari, D.; Monfardini, A.; Natoli, P.; Negrello, M.; Notari, A.; Paiella, A.; Paoletti, D.; Patanchon, G.; Piat, M.; Pisano, G.; Polastri, L.; Polenta, G.; Pollo, A.; Poulin, V.; Quartin, M.; Remazeilles, M.; Roman, M.; Rubino-Martin, J.-A.; Salvati, L.; Tartari, A.; Tomasi, M.; Tramonte, D.; Trappe, N.; Trombetti, T.; Tucker, C.; Valiviita, J.; Van de Weijgaert, R.; van Tent, B.; Vennin, V.; Vielva, P.; Vittorio, N.; Young, K.; Zannoni, M.

    2018-04-01

    Lensing of the cosmic microwave background (CMB) is now a well-developed probe of the clustering of the large-scale mass distribution over a broad range of redshifts. By exploiting the non-Gaussian imprints of lensing in the polarization of the CMB, the CORE mission will allow production of a clean map of the lensing deflections over nearly the full-sky. The number of high-S/N modes in this map will exceed current CMB lensing maps by a factor of 40, and the measurement will be sample-variance limited on all scales where linear theory is valid. Here, we summarise this mission product and discuss the science that will follow from its power spectrum and the cross-correlation with other clustering data. For example, the summed mass of neutrinos will be determined to an accuracy of 17 meV combining CORE lensing and CMB two-point information with contemporaneous measurements of the baryon acoustic oscillation feature in the clustering of galaxies, three times smaller than the minimum total mass allowed by neutrino oscillation measurements. Lensing has applications across many other science goals of CORE, including the search for B-mode polarization from primordial gravitational waves. Here, lens-induced B-modes will dominate over instrument noise, limiting constraints on the power spectrum amplitude of primordial gravitational waves. With lensing reconstructed by CORE, one can "delens" the observed polarization internally, reducing the lensing B-mode power by 60 %. This can be improved to 70 % by combining lensing and measurements of the cosmic infrared background from CORE, leading to an improvement of a factor of 2.5 in the error on the amplitude of primordial gravitational waves compared to no delensing (in the null hypothesis of no primordial B-modes). Lensing measurements from CORE will allow calibration of the halo masses of the tens of thousands of galaxy clusters that it will find, with constraints dominated by the clean polarization-based estimators. The 19

  2. Direct comparison of polymethylmetacrylate (PMMA) and silicone-on-glass (SOG) for Fresnel lenses in concentrating photovoltaics (CPV)

    Science.gov (United States)

    Annen, Hans Philipp; Fu, Ling; Leutz, Ralf; González, Luis; Mbakop, Jehu

    2011-09-01

    The CPV community is still undecided on one critical issue: what material to use best for Fresnel lens parquets. Reliability and longevity are the most important, but all other properties play roles as well. We have developed and manufactured Fresnel lenses with the two commonly used materials: PMMA (Polymethylmethacrylate) and silicone on glass (SOG). Both lenses are designed for the same optical train for best comparability. This allows for better understanding the pros and cons of the materials and making an informed choice for a specific CPV module. While PMMA lenses are embossed from pre-fab sheets in a hot-cold process, the silicone lenses are cast from a heat-curing silicone rubber at moderate temperatures, reducing the energy consumption. PMMA allows for the inclusion of custom low-profile 3D (2.5D) structures for module assembly and mechanical alignment, a feature not possible in silicone due to its low rigidity. Both lenses suffer from thermal expansion and refractive index change. While PMMA parquets expand isotropically, SOG prisms deform due to the difference of expansion coefficients between the glass and the silicone. SOG lenses are prone to delamination of the silicone film. The adhesive strength of the film to the glass can be measured using a modified blister test that we developed. The results show large difference with different materials and confirm the necessity of controlling this issue closely. While the small thermal expansion of the glass sheets allows for larger parquet sizes, the deformation of the prisms with temperature may cause a performance hit.

  3. Trend of digital camera and interchangeable zoom lenses with high ratio based on patent application over the past 10 years

    Science.gov (United States)

    Sensui, Takayuki

    2012-10-01

    Although digitalization has tripled consumer-class camera market scale, extreme reductions in prices of fixed-lens cameras has reduced profitability. As a result, a number of manufacturers have entered the market of the System DSC i.e. digital still camera with interchangeable lens, where large profit margins are possible, and many high ratio zoom lenses with image stabilization functions have been released. Quiet actuators are another indispensable component. Design with which there is little degradation in performance due to all types of errors is preferred for good balance in terms of size, lens performance, and the rate of quality to sub-standard products. Decentering, such as that caused by tilting, sensitivity of moving groups is especially important. In addition, image stabilization mechanisms actively shift lens groups. Development of high ratio zoom lenses with vibration reduction mechanism is confronted by the challenge of reduced performance due to decentering, making control over decentering sensitivity between lens groups everything. While there are a number of ways to align lenses (axial alignment), shock resistance and ability to stand up to environmental conditions must also be considered. Naturally, it is very difficult, if not impossible, to make lenses smaller and achieve a low decentering sensitivity at the same time. 4-group zoom construction is beneficial in making lenses smaller, but decentering sensitivity is greater. 5-group zoom configuration makes smaller lenses more difficult, but it enables lower decentering sensitivities. At Nikon, the most advantageous construction is selected for each lens based on specifications. The AF-S DX NIKKOR 18-200mm f/3.5-5.6G ED VR II and AF-S NIKKOR 28-300mm f/3.5-5.6G ED VR are excellent examples of this.

  4. What is Gravitational Lensing? (LBNL Summer Lecture Series)

    Energy Technology Data Exchange (ETDEWEB)

    Leauthaud, Alexie; Nakajima, Reiko [Berkeley Center for Cosmological Physics

    2009-07-28

    Summer Lecture Series 2009: Gravitational lensing is explained by Einstein's general theory of relativity: galaxies and clusters of galaxies, which are very massive objects, act on spacetime by causing it to become curved. Alexie Leauthaud and Reiko Nakajima, astrophysicists with the Berkeley Center for Cosmological Physics, will discuss how scientists use gravitational lensing to investigate the nature of dark energy and dark matter in the universe.

  5. Bilateral spontaneous subluxation of scleral-fixated intraocular lenses.

    Science.gov (United States)

    Assia, Ehud I; Nemet, Arie; Sachs, Dani

    2002-12-01

    Two young men with primary ectopic lenses had intracapsular cataract extraction and scleral fixation of posterior chamber intraocular lenses (PC IOLs) using 10-0 polypropylene sutures tied to the IOL eyelets. Three to 9 years after implantation, spontaneous IOL vertical subluxation occurred in all 4 eyes (5 IOL loops), probably because of suture breakage. Late subluxation of a sutured IOL may occur several years after implantation. Double fixation and thicker sutures should be considered, especially in young patients.

  6. Periodic self-lensing from accreting massive black hole binaries

    Science.gov (United States)

    D'Orazio, Daniel J.; Di Stefano, Rosanne

    2018-03-01

    Nearly 150 massive black hole binary (MBHB) candidates at sub-pc orbital separations have been reported in recent literature. Nevertheless, the definitive detection of even a single such object remains elusive. If at least one of the black holes is accreting, the light emitted from its accretion disc will be lensed by the other black hole for binary orbital inclinations near to the line of sight. This binary self-lensing could provide a unique signature of compact MBHB systems. We show that, for MBHBs with masses in the range 106-1010 M⊙ and with orbital periods less than ˜10 yr, strong lensing events should occur in one to 10s of per cent of MBHB systems that are monitored for an entire orbit. Lensing events will last from days for the less massive, shorter period MBHBs to a year for the most massive ˜10 year orbital period MBHBs. At small inclinations of the binary orbit to the line of sight, lensing must occur and will be accompanied by periodicity due to the relativistic Doppler boost. Flares at the same phase as the otherwise average flux of the Doppler modulation would be a smoking gun signature of self-lensing and can be used to constrain binary parameters. For MBHBs with separation ≳100 Schwarzschild radii, we show that finite-sized source effects could serve as a probe of MBH accretion disc structure. Finally, we stress that our lensing probability estimate implies that ˜10 of the known MBHB candidates identified through quasar periodicity should exhibit strong lensing flares.

  7. Optical and visual performance of aspheric soft contact lenses.

    Science.gov (United States)

    Efron, Suzanne; Efron, Nathan; Morgan, Philip B

    2008-03-01

    This study was conducted to investigate whether aspheric design soft contact lenses reduce ocular aberrations and result in better visual acuity and subjective appreciation of clinical performance compared with spherical soft contact lenses. A unilateral, double-masked, randomized and controlled study was undertaken in which ocular aberrations and high and low contrast logMAR visual acuity were measured on myopic subjects who wore aspheric design (Biomedics 55 Evolution, CooperVision) and spherical design (Biomedics 55, CooperVision) soft contact lenses. Ten subjects who had about -2.00 D myopia wore -2.00 D lenses and 10 subjects who had about -5.00 D myopia wore -5.00 D lenses. Measurements were made under photopic and mesopic lighting conditions. Subjects were invited to grade comfort, vision in photopic and mesopic conditions, and overall impression with the two lens types on 100 unit visual analogue scales. There was no significant difference in high contrast or low contrast visual acuity between the two lens designs of either power under photopic or mesopic conditions. Both lens designs displayed lower levels of spherical aberration compared with the "no lens" condition under photopic and mesopic light levels (p designs. There were no statistically significant differences in subjective appreciation of clinical performance between lens designs or lens powers. At least with respect to the brand of lenses tested, the fitting of aspheric design soft contact lenses does not result in superior visual acuity, aberration control, or subjective appreciation compared with equivalent spherical design soft contact lenses.

  8. Lensing bias to CMB polarization measurements of compensated isocurvature perturbations

    Science.gov (United States)

    Heinrich, Chen

    2018-01-01

    Compensated isocurvature perturbations (CIPs) are opposite spatial fluctuations in the baryon and dark matter (DM) densities. They arise in the curvaton model and some models of baryogenesis. While the gravitational effects of baryon fluctuations are compensated by those of DM, leaving no observable impacts on the cosmic microwave background (CMB) at first order, they modulate the sound horizon at recombination, thereby correlating CMB anisotropies at different multipoles. As a result, CIPs can be reconstructed using quadratic estimators similarly to CMB detection of gravitational lensing. Because of these similarities, however, the CIP estimators are biased with lensing contributions that must be subtracted. These lensing contributions for CMB polarization measurement of CIPs are found to roughly triple the noise power of the total CIP estimator on large scales. In addition, the cross power with temperature and E -mode polarization are contaminated by lensing-ISW (integrated Sachs-Wolfe) correlations and reionization-lensing correlations respectively. For a cosmic-variance-limited temperature and polarization experiment measuring out to multipoles lmax=2500 , the lensing noise raises the detection threshold by a factor of 1.5, leaving a 2.7 σ detection possible for the maximal CIP signal in the curvaton model.

  9. Cosmological constraints from weak lensing non-Gaussian statistics

    Science.gov (United States)

    Liu, Jia; Haiman, Zoltan; Petri, Andrea; Hill, James; Hui, Lam; Kratochvil, Jan Michael; May, Morgan

    2016-01-01

    Weak gravitational lensing is one of the most promising techniques to probe dark energy. Our work to date suggests that the information in the nonlinear regime exceeds that in the two-point functions. Using the publicly available data from the 154 deg^2 CFHTLenS survey and a large suite of ray-tracing N-body simulations on a grid of 91 cosmological models, we find that constraints from peak counts are comparable to those from the power spectrum, and somewhat tighter when different smoothing scales are combined.I will also introduce the utility of cross-correlating weak galaxy lensing maps with CMB lensing maps, a technique that will be useful to probe structures at an intermediate redshift of 0.9, as larger weak lensing surveys such as HSC, DES, KiDS, Euclid, and LSST come online. We cross-correlate the CFHTLenS galaxy lensing convergence maps with Planck CMB lensing maps. Our results show two sigma tension with the constraints obtained from the Planck temperature measurements. I will discuss possible sources of the tension, including intrinsic alignments, photo-z uncertainties, masking of tSZ in the CMB maps, and the multiplicative bias.

  10. Invited Review Article: Development of crystal lenses for energetic photons

    International Nuclear Information System (INIS)

    Smither, Robert K.

    2014-01-01

    This paper follows the development of crystal diffraction lenses designed to focus energetic photons. It begins with the search for a solution to the astrophysics problem of how to detect weak astrophysics sources of gamma rays and x-rays. This led to the basic designs for a lens and to the understanding of basic limitations of lens design. The discussion of the development of crystal diffraction lenses is divided into two parts: lenses using crystals with mosaic structure, and lenses that use crystals with curved crystal planes. This second group divides into two sub-groups: (1) Curved crystals that are used to increase the acceptance angle of the diffraction of a monochromatic beam and to increase the energy bandwidth of the diffraction. (2) Curved crystals used to focus gamma ray beams. The paper describes how these two types of crystals affect the design of the corresponding crystal lenses in different fields: astrophysics, medical imaging, detection of weak, distant, gamma-ray sources, etc. The designs of crystal lenses for these applications are given in enough detail to allow the reader to design a lens for his own application

  11. Scleral contact lenses for the management of complicated ptosis.

    Science.gov (United States)

    Katsoulos, Konstantinos; Rallatos, Gerasimos Livir; Mavrikakis, Ioannis

    2017-10-20

    To present the management of three patients suffering from ptosis of various etiologies, with scleral contact lenses. Three patients (five eyes) with ptosis resulting from levator dehiscence due to long-term rigid gas permeable contact lens wear for keratoconus, phthisis bulbi, and myopathy due to Kearns-Sayre syndrome were identified during a 2-year period. They were fitted with scleral contact lenses in order to provide cosmesis by lifting the upper eyelid with the bulk of the lens, and simultaneously provide vision correction where applicable. The scleral contact lenses provided comfortable wear, significantly improved cosmesis as both palpebral aperture and marginal reflex distance were increased, and visual acuity was also subjectively and objectively improved. Two of the patients opted for the scleral contact lenses, whereas the parents of the third patient, a 10-year-old girl with Kearns-Sayre syndrome, chose to undergo ptosis surgery due to handling issues of the scleral contact lenses. Scleral contact lenses can be a useful addition to the treatment option for patients with complicated ptosis.

  12. Chromatic confocal microscope using hybrid aspheric diffractive lenses

    Science.gov (United States)

    Rayer, Mathieu; Mansfield, Daniel

    2014-05-01

    A chromatic confocal microscope is a single point non-contact distance measurement sensor. For three decades the vast majority of the chromatic confocal microscope use refractive-based lenses to code the measurement axis chromatically. However, such an approach is limiting the range of applications. In this paper the performance of refractive, diffractive and Hybrid aspheric diffractive are compared. Hybrid aspheric diffractive lenses combine the low geometric aberration of a diffractive lens with the high optical power of an aspheric lens. Hybrid aspheric diffractive lenses can reduce the number of elements in an imaging system significantly or create large hyper- chromatic lenses for sensing applications. In addition, diffractive lenses can improve the resolution and the dynamic range of a chromatic confocal microscope. However, to be suitable for commercial applications, the diffractive optical power must be significant. Therefore, manufacturing such lenses is a challenge. We show in this paper how a theoretical manufacturing model can demonstrate that the hybrid aspheric diffractive configuration with the best performances is achieved by step diffractive surface. The high optical quality of step diffractive surface is then demonstrated experimentally. Publisher's Note: This paper, originally published on 5/10/14, was replaced with a corrected/revised version on 5/19/14. If you downloaded the original PDF but are unable to access the revision, please contact SPIE Digital Library Customer Service for assistance.

  13. Question Their Answers

    Science.gov (United States)

    Royce, Brenda

    2004-10-01

    Brenda Royce has been teaching high school chemistry and physics for nine years, and is currently science department chair at University High School in Fresno, CA, a college prep charter school on the CSU Fresno campus. She also enjoys coaching Science Olympiad, and working with science and math student teachers as a workshop leader and mentor teacher through the Science and Math Education Center at CSUF. Prior to teaching, she worked in analytical and environmental chemistry for several years. Brenda shares with us her strategy of answering students' questions by "questioning their answers."

  14. The Initial Mass Function in the Nearest Strong Lenses from SNELLS: Assessing the Consistency of Lensing, Dynamical, and Spectroscopic Constraints

    Energy Technology Data Exchange (ETDEWEB)

    Newman, Andrew B. [The Observatories of the Carnegie Institution for Science, Pasadena, CA (United States); Smith, Russell J. [Centre for Extragalactic Astronomy, University of Durham, South Road, Durham (United Kingdom); Conroy, Charlie [Department of Astronomy, Harvard University, Cambridge, MA (United States); Villaume, Alexa [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA (United States); Van Dokkum, Pieter, E-mail: anewman@obs.carnegiescience.edu [Department of Astrophysical Sciences, Yale University, New Haven, CT (United States)

    2017-08-20

    We present new observations of the three nearest early-type galaxy (ETG) strong lenses discovered in the SINFONI Nearby Elliptical Lens Locator Survey (SNELLS). Based on their lensing masses, these ETGs were inferred to have a stellar initial mass function (IMF) consistent with that of the Milky Way, not the bottom-heavy IMF that has been reported as typical for high- σ ETGs based on lensing, dynamical, and stellar population synthesis techniques. We use these unique systems to test the consistency of IMF estimates derived from different methods. We first estimate the stellar M {sub *}/ L using lensing and stellar dynamics. We then fit high-quality optical spectra of the lenses using an updated version of the stellar population synthesis models developed by Conroy and van Dokkum. When examined individually, we find good agreement among these methods for one galaxy. The other two galaxies show 2–3 σ tension with lensing estimates, depending on the dark matter contribution, when considering IMFs that extend to 0.08 M {sub ⊙}. Allowing a variable low-mass cutoff or a nonparametric form of the IMF reduces the tension among the IMF estimates to <2 σ . There is moderate evidence for a reduced number of low-mass stars in the SNELLS spectra, but no such evidence in a composite spectrum of matched- σ ETGs drawn from the SDSS. Such variation in the form of the IMF at low stellar masses ( m ≲ 0.3 M {sub ⊙}), if present, could reconcile lensing/dynamical and spectroscopic IMF estimates for the SNELLS lenses and account for their lighter M {sub *}/ L relative to the mean matched- σ ETG. We provide the spectra used in this study to facilitate future comparisons.

  15. Prosthetic soft contact lenses in Japan.

    Science.gov (United States)

    Kanemoto, Masumi; Toshida, Hiroshi; Takahiro, Itagaki; Murakami, Akira

    2007-11-01

    To investigate the use of the prosthetic iris-tinted soft contact lens, the SEED Opaque, during the past 5 years. The records of 42 outpatients (48 eyes) for whom the prosthetic soft contact lens was prescribed in the contact lens clinic of Juntendo University Hospital from July 2001 to June 2005 were investigated. An investigation was conducted in regard to the tint patterns of the prosthetic soft contact lens and the presence or absence of a transparent part in the middle, as a brown iris with a clear pupil or a solid pupil. The diagnosis, purpose of prescription, age when that lens was prescribed, complications, and changes in corrected visual acuities were analyzed retrospectively from the medical records. The mean age at the first prescription, total number of years of wearing prosthetic contact lenses, total number of prescriptions, and mean period to use each SEED Opaque lens were compared. The mean age at the first prescription of solid-pupil lens wearers was significantly younger than that for clear-pupil lens wearers (Ppossible to adjust the color and size of the cosmetic part and the pupil diameter. Further, corrected visual acuities could improve with the clear-pupil type for patients who had prescribed for improvement of visual function.

  16. Efficient lensing element for x-rays

    International Nuclear Information System (INIS)

    Ceglio, N.M.; Smith, H.I.

    1977-01-01

    An efficient x-ray lens with an effective speed of order less than approximately f/50 for lambda greater than approximately 10 A x-rays is described. Fabrication of this lensing element appears feasible using existing microfabrication technology. Diffraction and refraction are coupled in a single element to achieve efficient x-ray concentration into a single order focal spot. Diffraction is used to produce efficient ray bending (without absorption) while refraction is used only to provide appropriate phase adjustment among the various diffraction orders to insure what is essentially a single order output. The mechanism for ray bending (diffraction) is decoupled from the absorption mechanism. Refraction is used only to achieve small shifts in phase so that the associated attenuation need not be prohibitive. The x-ray lens might be described as a Blazed Fresnel Phase Plate (BFPP) with a spatially distributed phase shift within each Fresnel zone. The spatial distribution of the phase shifts is chosen to concentrate essentially all of the unabsorbed energy into a single focal spot. The BFPP transforms the incident plane wave into a converging spherical wave having an amplitude modulation which is periodic in r 2 . As a result of the periodic amplitude modulation, the BFPP will diffract energy into foci other than the first order real focus. In cases of small absorption such effects are negligible and practically all the unabsorbed energy is directed into the first order real focus

  17. Pathogenic Free-Living Amoebae Isolated From Contact Lenses of Keratitis Patients.

    Science.gov (United States)

    Hajialilo, Elham; Niyyati, Maryam; Solaymani, Mohammad; Rezaeian, Mostafa

    2015-01-01

    Free-living amoeba (FLA)-related keratitis is a progressive infection of the cornea with poor prognosis. The present study aimed to investigates the contact lenses of patients with keratitis for pathogenic free-living amoebae. Overall, 62 contact lenses and their paraphernalia of patients with keratitis cultured and tested for the presence of free-living amoebae using morphological criteria. Unusual plates including plates containing mix amoebae and Vermamoeba were submitted to molecular analysis. Out of 62 plates, 11 revealed the outgrowth of free living amoeba of which 9 were Acanthamoeba, one plates contained mix amoebae including Acanthamoeba and Vermamoeba and one showed the presence of Vermamoeba. These two latter plates belonged to patients suffered from unilateral keratitis due to the misused of soft contact lenses. One of the patients had mix infection of Acanthamoeba (T4) and V. vermiformis meanwhile the other patient was infected with the V. vermiformis. Amoebic keratitis continues to rise in Iran and worldwide. To date, various genera of free-living amoebae such as Vermamoeba could be the causative agent of keratitis. Soft contact lens wearers are the most affected patients in the country, thus awareness of high-risk people for preventing free-living amoebae related keratitis is of utmost importance.

  18. Accurate weak lensing of standard candles. II. Measuring σ8 with supernovae

    Science.gov (United States)

    Quartin, Miguel; Marra, Valerio; Amendola, Luca

    2014-01-01

    Soon the number of type Ia supernova (SN) measurements should exceed 100 000. Understanding the effect of weak lensing by matter structures on the supernova brightness will then be more important than ever. Although SN lensing is usually seen as a source of systematic noise, we will show that it can be in fact turned into signal. More precisely, the non-Gaussianity introduced by lensing in the SN Hubble diagram dispersion depends rather sensitively on the amplitude σ8 of the matter power spectrum. By exploiting this relation, we are able to predict constraints on σ8 of 7% (3%) for a catalog of 100 000 (500 000) SNe of average magnitude error 0.12, without having to assume that such intrinsic dispersion and its redshift evolution are known a priori. The intrinsic dispersion has been assumed to be Gaussian; possible intrinsic non-Gaussianities in the data set (due to the SN themselves and/or to other transients) could be potentially dealt with by means of additional nuisance parameters describing higher moments of the intrinsic dispersion distribution function. This method is independent of and complementary to the standard methods based on cosmic microwave background, cosmic shear, or cluster abundance observables.

  19. Testing the Speed of Gravitational Waves over Cosmological Distances with Strong Gravitational Lensing.

    Science.gov (United States)

    Collett, Thomas E; Bacon, David

    2017-03-03

    Probing the relative speeds of gravitational waves and light acts as an important test of general relativity and alternative theories of gravity. Measuring the arrival time of gravitational waves (GWs) and electromagnetic (EM) counterparts can be used to measure the relative speeds, but only if the intrinsic time lag between emission of the photons and gravitational waves is well understood. Here we suggest a method that does not make such an assumption, using future strongly lensed GW events and EM counterparts; Biesiada et al. [J. Cosmol. Astropart. Phys.10 (2014) 080JCAPBP1475-751610.1088/1475-7516/2014/10/080] forecast that 50-100 strongly lensed GW events will be observed each year with the Einstein Telescope. A single strongly lensed GW event would produce robust constraints on c_{GW}/c_{γ} at the 10^{-7} level, if a high-energy EM counterpart is observed within the field of view of an observing γ-ray burst monitor.

  20. Pathogenic Free-Living Amoebae Isolated From Contact Lenses of Keratitis Patients

    Directory of Open Access Journals (Sweden)

    Elham HAJIALILO

    2015-12-01

    Full Text Available Background: Free-living amoeba (FLA-related keratitis is a progressive infection of the cornea with poor prognosis. The present study aimed to investigates the con­tact lenses of patients with keratitis for pathogenic free-living amoebae.Methods: Overall, 62 contact lenses and their paraphernalia of patients with kerati­tis cultured and tested for the presence of free-living amoebae using morphological criteria. Unusual plates including plates containing mix amoebae and Vermamoeba were submitted to molecular analysis. Results: Out of 62 plates, 11 revealed the outgrowth of free living amoeba of which 9 were Acanthamoeba, one plates contained mix amoebae including Acan­thamoeba and Vermamoeba and one showed the presence of Vermamoeba. These two latter plates belonged to patients suffered from unilateral keratitis due to the mis­used of soft contact lenses. One of the patients had mix infection of Acanthamoeba (T4 and V. vermiformis meanwhile the other patient was infected with the V. vermiformis. Conclusion: Amoebic keratitis continues to rise in Iran and worldwide. To date, various genera of free-living amoebae such as Vermamoeba could be the causative agent of keratitis. Soft contact lens wearers are the most affected patients in the country, thus awareness of high-risk people for preventing free-living amoebae re­lated keratitis is of utmost importance.

  1. A 2500 deg 2 CMB Lensing Map from Combined South Pole Telescope and Planck Data

    Energy Technology Data Exchange (ETDEWEB)

    Omori, Y.; Chown, R.; Simard, G.; Story, K. T.; Aylor, K.; Baxter, E. J.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Cho, H-M.; Crawford, T. M.; Crites, A. T.; Haan, T. de; Dobbs, M. A.; Everett, W. B.; George, E. M.; Halverson, N. W.; Harrington, N. L.; Holder, G. P.; Hou, Z.; Holzapfel, W. L.; Hrubes, J. D.; Knox, L.; Lee, A. T.; Leitch, E. M.; Luong-Van, D.; Manzotti, A.; Marrone, D. P.; McMahon, J. J.; Meyer, S. S.; Mocanu, L. M.; Mohr, J. J.; Natoli, T.; Padin, S.; Pryke, C.; Reichardt, C. L.; Ruhl, J. E.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Staniszewski, Z.; Stark, A. A.; Vanderlinde, K.; Vieira, J. D.; Williamson, R.; Zahn, O.

    2017-11-07

    We present a cosmic microwave background (CMB) lensing map produced from a linear combination of South Pole Telescope (SPT) and \\emph{Planck} temperature data. The 150 GHz temperature data from the $2500\\ {\\rm deg}^{2}$ SPT-SZ survey is combined with the \\emph{Planck} 143 GHz data in harmonic space, to obtain a temperature map that has a broader $\\ell$ coverage and less noise than either individual map. Using a quadratic estimator technique on this combined temperature map, we produce a map of the gravitational lensing potential projected along the line of sight. We measure the auto-spectrum of the lensing potential $C_{L}^{\\phi\\phi}$, and compare it to the theoretical prediction for a $\\Lambda$CDM cosmology consistent with the \\emph{Planck} 2015 data set, finding a best-fit amplitude of $0.95_{-0.06}^{+0.06}({\\rm Stat.})\\! _{-0.01}^{+0.01}({\\rm Sys.})$. The null hypothesis of no lensing is rejected at a significance of $24\\,\\sigma$. One important use of such a lensing potential map is in cross-correlations with other dark matter tracers. We demonstrate this cross-correlation in practice by calculating the cross-spectrum, $C_{L}^{\\phi G}$, between the SPT+\\emph{Planck} lensing map and Wide-field Infrared Survey Explorer (\\emph{WISE}) galaxies. We fit $C_{L}^{\\phi G}$ to a power law of the form $p_{L}=a(L/L_{0})^{-b}$ with $a=2.15 \\times 10^{-8}$, $b=1.35$, $L_{0}=490$, and find $\\eta^{\\phi G}=0.94^{+0.04}_{-0.04}$, which is marginally lower, but in good agreement with $\\eta^{\\phi G}=1.00^{+0.02}_{-0.01}$, the best-fit amplitude for the cross-correlation of \\emph{Planck}-2015 CMB lensing and \\emph{WISE} galaxies over $\\sim67\\%$ of the sky. The lensing potential map presented here will be used for cross-correlation studies with the Dark Energy Survey (DES), whose footprint nearly completely covers the SPT $2500\\ {\\rm deg}^2$ field.

  2. Towards an understanding of dark matter: Precise gravitational lensing analysis complemented by robust photometric redshifts

    Science.gov (United States)

    Coe, Daniel Aaron

    The goal of thesis is to help scientists resolve one of the great mysteries of our time: the nature of Dark Matter. Dark Matter is currently believed to make up over 80% of the material in our universe, yet we have so far inferred but a few of its basic properties. Here we study the Dark Matter surrounding a galaxy cluster, Abell 1689, via the most direct method currently available--gravitational lensing. Abell 1689 is a "strong" gravitational lens, meaning it produces multiple images of more distant galaxies. The observed positions of these images can be measured very precisely and act as a blueprint allowing us to reconstruct the Dark Matter distribution of the lens. Until now, such mass models of Abell 1689 have reproduced the observed multiple images well but with significant positional offsets. Using a new method we develop here, we obtain a new mass model which perfectly reproduces the observed positions of 168 knots identified within 135 multiple images of 42 galaxies. An important ingredient to our mass model is the accurate measurement of distances to the lensed galaxies via their photometric redshifts. Here we develop tools which improve the accuracy of these measurements based on our study of the Hubble Ultra Deep Field, the only image yet taken to comparable depth as the magnified regions of Abell 1689. We present results both for objects in the Hubble Ultra Deep Field and for galaxies gravitationally lensed by Abell 1689. As part of this thesis, we also provide reviews of Dark Matter and Gravitational Lensing, including a chapter devoted to the mass profiles of Dark Matter halos realized in simulations. The original work presented here was performed primarily by myself under the guidance of Narciso Benítez and Holland Ford as a member of the Advanced Camera for Surveys GTO Science Team at Johns Hopkins University and the Instituto de Astrofisica de Andalucfa. My advisors served on my thesis committee along with Rick White, Gabor Domokos, and Steve

  3. Fluid Lensing and Applications to Remote Sensing of Aquatic Environments

    Science.gov (United States)

    Chirayath, Ved

    2017-01-01

    The use of fluid lensing technology on UAVs is presented as a novel means for 3D imaging of aquatic ecosystems from above the water's surface at the centimeter scale. Preliminary results are presented from airborne fluid lensing campaigns conducted over the coral reefs of Ofu Island, American Samoa (2013) and the stromatolite reefs of Shark Bay, Western Australia (2014), covering a combined area of 15km2. These reef ecosystems were revealed with centimetre-scale 2D resolution, and an accompanying 3D bathymetry model was derived using fluid lensing, Structure from Motion and UAV position data. Data products were validated from in-situ survey methods including underwater calibration targets, depth measurements and millimetre-scale high-dynamic range gigapixel photogrammetry. Fluid lensing is an experimental technology that uses water transmitting wavelengths to passively image underwater objects at high-resolution by exploiting time-varying optical lensing events caused by surface waves. Fluid lensing data are captured from low-altitude, cost-effective electric UAVs to achieve multispectral imagery and bathymetry models at the centimetre scale over regional areas. As a passive system, fluid lensing is presently limited by signal-to-noise ratio and water column inherent optical properties to approximately 10 m depth over visible wavelengths in clear waters. The datasets derived from fluid lensing present the first centimetre-scale images of a reef acquired from above the ocean surface, without wave distortion. The 3D multispectral data distinguish coral, fish and invertebrates in American Samoa, and reveal previously undocumented, morphologically distinct, stromatolite structures in Shark Bay. These findings suggest fluid lensing and multirotor electric drones represent a promising advance in the remote sensing of aquatic environments at the centimetre scale, or 'reef scale' relevant to the conservation of reef ecosystems. Pending further development and validation of

  4. A question of emphasis

    DEFF Research Database (Denmark)

    Almarsdóttir, Anna Birna; Morgall, Janine Marie; Björnsdóttir, I

    2000-01-01

    The reported results are part of the overall evaluation of the new drug distribution legislation that went into effect in March 1996, liberalising ownership of community pharmacies in Iceland. We addressed the following question: What impact did the legislation have on users' access to and costs...

  5. A freedom to question...

    Indian Academy of Sciences (India)

    Lawrence

    the family about things he had read and studied opened up the entire world of academia to me. Here, it seemed that one could as an adult pursue one's interests single-mindedly, without worries about earning a living! Until class ten, I also had very good teach- ers who encouraged questioning. I enjoyed listening to and re-.

  6. Transportation questions and answers

    International Nuclear Information System (INIS)

    1989-01-01

    This document summarizes the transport and handling of radioactive materials in a ''question'' and ''answer'' form. It explains what is radioactive material, how it is shipped, and in case there is a spill, who is responsible for it. It also provides safeguard measures for radioactive materials. (TC)

  7. Structured Attentions for Visual Question Answering

    OpenAIRE

    Zhu, Chen; Zhao, Yanpeng; Huang, Shuaiyi; Tu, Kewei; Ma, Yi

    2017-01-01

    Visual attention, which assigns weights to image regions according to their relevance to a question, is considered as an indispensable part by most Visual Question Answering models. Although the questions may involve complex relations among multiple regions, few attention models can effectively encode such cross-region relations. In this paper, we demonstrate the importance of encoding such relations by showing the limited effective receptive field of ResNet on two datasets, and propose to mo...

  8. Lense op spiritualiteit en kerkwees: Die pad vorentoe vir die Nederduitsch Hervormde Kerk van Afrika (NHKA

    Directory of Open Access Journals (Sweden)

    Jacobus C. van der Merwe

    2013-07-01

    Full Text Available Lenses on spirituality and being church; the road ahead for the Netherdutch Reformed Church of Africa (NRCA. At this point of time the Netherdutch Reformed Church of Africa (NRCA is facing the seemingly unsolvable dilemma of not being able to handle diversity in a positive manner. By applying three lenses to the current impasse with regards to the church’s struggle with diversity, this article aims at providing an answer to the question of how to proceed. The first lens addresses the challenge to maintain spiritual health and harmony in the midst of differences and tension in the church. The theory behind systems sensitive leadership as lens serves as the guideline to achieve the necessary spiritual health that the church needs in such challenging times. The second lens explores the inner Christian spiritual path in a both developmental and comprehensive way. Drawing on the work of Paul Smith this lens sets forth the developmental framework by which Christians grow inwardly in their understanding of Jesus and his teachings. The third lens is a view on a practice whereby the validity of intellectual positions, statements, or ideologies could be appraised as an innate quality in any subject. This lens opens a unique perspective which provides not only a new understanding of humanity’s journey in the universe, but also serves as a guide to were we and the whole cosmos are on our personal journeys to become who we could be. The vision that is provided by these three lenses has the capacity not only to serve as guidelines, but also to provide the tools to handle the challenges the church has to face on the road a head.

  9. Questions about elastic waves

    CERN Document Server

    Engelbrecht, Jüri

    2015-01-01

    This book addresses the modelling of mechanical waves by asking the right questions about them and trying to find suitable answers. The questions follow the analytical sequence from elementary understandings to complicated cases, following a step-by-step path towards increased knowledge. The focus is on waves in elastic solids, although some examples also concern non-conservative cases for the sake of completeness. Special attention is paid to the understanding of the influence of microstructure, nonlinearity and internal variables in continua. With the help of many mathematical models for describing waves, physical phenomena concerning wave dispersion, nonlinear effects, emergence of solitary waves, scales and hierarchies of waves as well as the governing physical parameters are analysed. Also, the energy balance in waves and non-conservative models with energy influx are discussed. Finally, all answers are interwoven into the canvas of complexity.

  10. After sympathy, a question

    DEFF Research Database (Denmark)

    Dalsgård, Anne Line

    2018-01-01

    in particular one young woman's telling of a likewise fictional romantic ending to Dalsgård's piece. The argument developed in the chapter leads to a definition of friendship, which is based on the mutual recognition of difference. It also leads to a question of responsi-bility, which transcends the framework......Within a discussion of fieldwork, friendship and ethics Dalsgård describes how a piece of fictional writing worked as a sympathetic experiment and both changed her understanding of a young woman's situation and deepened her relationship to her. She employs Adam Smith’s concept of sympathy...... excites it. The precondition for sympathy is thus a willingness to let oneself be moved by the situation of the other, which implies a thorough insight into all that this situation consists of. However, Dalsgård argues, sympathy may lead to a question about the proper response to the distress of another...

  11. Characterizing Lenses and Lensed Stars of High-magnification Single-lens Gravitational Microlensing Events with Lenses Passing over Source Stars

    DEFF Research Database (Denmark)

    Choi, J.-Y; Park, S.-Y; Han, C.

    2012-01-01

    -source effect. For seven events, we measure the Einstein radii and the lens-source relative proper motions. Among them, five events are found to have Einstein radii of less than 0.2 mas, making the lenses very low mass star or brown dwarf candidates. For MOA-2011-BLG-274, especially, the small Einstein radius...

  12. 501 reading comprehension questions

    CERN Document Server

    2014-01-01

    This updated edition offers the most extensive and varied practice for all types of questions students might face on standardized and in-class tests. With this guide, students will learn to develop expert reading strategies, understand how to read faster and with greater comprehension, overcome reading anxiety, and increase appreciation of reading for pleasure. This book's step-by-step approach provides graduated coverage that moves from the basics to more advanced reading.

  13. Eight Questions about Corruption

    OpenAIRE

    Jakob Svensson

    2005-01-01

    This paper will discuss eight frequently asked questions about public corruption: (1) What is corruption? (2) Which countries are the most corrupt? (3) What are the common characteristics of countries with high corruption? (4) What is the magnitude of corruption? (5) Do higher wages for bureaucrats reduce corruption? (6) Can competition reduce corruption? (7) Why have there been so few (recent) successful attempts to fight corruption? (8) Does corruption adversely affect growth?

  14. The Question Concerning Thinking

    DEFF Research Database (Denmark)

    Riis, Søren

    2008-01-01

    Martin Heidegger's thought-provoking essay "The Question Concerning Technology" (1977a) placed technology at the heart of philosophy. Heidegger tried to show that the essence of technology provokes humans to think about the world in a very dangerous way. Yet if we follow Heidegger's analysis of t...... concerning thinking reflects these consequences and finally strives to find another way to think about thinking - a way that brings us back to another of Heidegger's thoughts and that makes it possible to appreciate the work of thought......Martin Heidegger's thought-provoking essay "The Question Concerning Technology" (1977a) placed technology at the heart of philosophy. Heidegger tried to show that the essence of technology provokes humans to think about the world in a very dangerous way. Yet if we follow Heidegger's analysis...... of technology, what role does that ascribe to philosophy? To be able to understand the programmatic scope of Heidegger's question ‘concerning' technology, we need to see it as inseparable from his famous thesis about the end of philosophy (1977c) and what he considers to be the ideal kind of thinking. However...

  15. Comparison between liquid and solid tunable focus lenses

    Energy Technology Data Exchange (ETDEWEB)

    Santiago-Alvarado, A; Cruz-Martinez, V M [Universidad Tecnologica de la Mixteca, Carre. Acatlima Km 2.5 Huajuapan de Leon Oaxaca (Mexico); Vazquez-Montiel, S; Munoz-Lopez, J; Diaz-Gonzalez, G [Instituto Nacional de Astrofisica, Optica y Electronica Luis Enrique Erro 1, Tonantzintla Puebla (Mexico); Campos-Garcia, M, E-mail: santiago@mixteco.utm.mx [Centro de Ciencias Aplicadas y Desarrollo Tecnologico, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70-186, 04510, D.F. Mexico (Mexico)

    2011-01-01

    Nowadays more reports in the use of tunable lenses are reported, it is due to the benefits they offer in optical systems design. A tunable lens is an optical system that can focus on a range of positions by changing dynamically one of its geometric parameters. There are several types of tunable lenses, the most known types are the liquid, the solid elastic, with variable refractive index, and lenses that use a dielectric medium. This paper presents the analysis and opto-mechanical design of two tunable lenses, a liquid lens and another Solid Elastic Lens (SEL). Both lenses are made in mounting aluminium and polydimethylsiloxane (PDMS) as refractor medium, the liquid lens use two elastic membranes containing a liquid medium between them while the SEL only use PDMS material as body of the lens (medium refractor). We describe the opto-mechanical performance of both types of lens highlighting the main features of each. Finally, results of a opto-functional comparison between these prototypes are showed.

  16. Advances in scleral lenses for refractive surgery complications.

    Science.gov (United States)

    Parminder, Amy; Jacobs, Deborah S

    2015-07-01

    The last two decades have brought advances in materials and manufacturing of large diameter rigid gas-permeable contact lenses, and a greater appreciation of the role of scleral lenses for therapeutic indications. The purpose of this review is to provide an update on the use of rigid gas-permeable scleral lenses in the management of patients with complications after refractive surgery. There are recent reports on clinical experience with specific scleral lens designs from single institutions in cohorts that include patients who have undergone refractive surgery. Typically, these are patients with 'irregular corneas' after radial keratotomy or LASER assisted in-situ keratomileusis, but patients with keratectasia, dry eye syndrome, and corneal neuralgia are also reported. Visual outcomes and wearing success rates are high in these reports, although outcomes for refractive surgery patients are not reported separately. Clinicians who encounter patients with complications after corneal refractive surgery should be aware of advances in scleral lenses. Scleral lenses are an alternative to surgical intervention in patients who might otherwise be considered poor contact lens candidates.

  17. Bacterial adherence to extended wear soft contact lenses

    International Nuclear Information System (INIS)

    Aswad, M.I.; John, T.; Barza, M.; Kenyon, K.; Baum, J.

    1990-01-01

    The authors studied the adherence of Pseudomonas aeruginosa and Staphylococcus aureus to extended wear soft contact lenses (EWSCLs) with and without focal deposits using both a radiolabeling technique and electron microscopy. P. aeruginosa showed significant adherence to contact lenses in vitro. In contrast, S. aureus failed to show significant adherence to contact lenses in vitro (i.e., the radioactive uptake was not significantly above background). The extent of adherence of Pseudomonas was proportional to the number of focal deposits on the lenses. Results of electron microscopic examination showed the bacteria to be adherent primarily to large focal deposits (greater than or equal to 150 microns). There was no pseudomonal adherence to the small focal deposits (less than or equal to 50 microns) and little adherence to the areas in between the focal deposits. The authors hypothesize that worn lenses, especially those with large focal deposits, serve as a vehicle for the transport of P. aeruginosa to the cornea. This hypothesis could be a partial explanation for the high incidence of keratitis caused by P. aeruginosa in EWSCL patients

  18. Objective and subjective evaluation of the performance of medical contact lenses fitted using a contact lens selection algorithm.

    Science.gov (United States)

    Visser, Esther-Simone; Wisse, Robert P L; Soeters, Nienke; Imhof, Saskia M; Van der Lelij, Allegonda

    2016-08-01

    To evaluate the performance of medical contact lenses (CLs) for a wide range of clinical indications. Prospective cross-sectional study. A total of 281 eyes were evaluated in 281 consecutive patients (≥18 years of age; CL use ≥3 months) who visited the contact lens service in a tertiary academic clinic for a scheduled follow-up visit. The main outcome measured were clinical indications for CL wear; CL type; change in corrected distance visual acuity (CDVA) with CL use; CL wearing duration; CL wearing time; subjective performance measured using a visual analog scale (VAS) questionnaire (score range: 0-100); and effectiveness of the lens-selection algorithm. Wearing CLs significantly improved CDVA compared to wearing spectacles (median change: -0.15 logMAR, range: 1.00 to -2.10; Pscleral lens and soft lens groups. The medical CL fitting was found to be generally effective (the overall satisfaction rating was ≥70 for 81% of patients). Fitting CLs based on the lens-selection algorithm yielded positive clinical results, including improved visual acuity, satisfactory wearing time, and high overall subjective performance. Moreover, subjective performance was similar between users of scleral lenses and users of soft lenses. These results underscore the importance of prescribing scleral lenses and the need for tertiary eye clinics to offer patients a variety of CL types. Copyright © 2016 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  19. The beat-wave accelerator: Twenty questions

    International Nuclear Information System (INIS)

    Lawson, J.D.

    1985-01-01

    Many questions in the field of accelerator physics, plasma physics and laser technology need to be addressed if a useful accelerator based on the beat-wave principle is to be constructed. Many of these must be considered together rather than sequentially. An attempt has been made to set out a number of the more important questions in a logical manner. (orig.)

  20. Aldose reductase activity and glucose-related opacities in incubated lenses from dogs and cats.

    Science.gov (United States)

    Richter, Marianne; Guscetti, Franco; Spiess, Bernhard

    2002-11-01

    To determine responses of canine and feline lenses to incubation in a medium with a high glucose concentration. Lenses from 35 dogs and 26 cats. Glucose concentrations were measured in paired lenses from 25 dogs and 17 cats after incubation for 14 days in high-glucose (30 mmol of glucose/L) or control (6 mmol of glucose/L) medium. Aldose reductase activity was measured spectrophotometrically in the incubated lenses and in freshly frozen lenses from 10 dogs and 9 cats. Two lenses of each group were studied histologically. Canine and feline lenses in high-glucose medium developed glucose-specific opacities of variable localization and extent. Canine lenses developed equatorial vacuoles, but severity of the lesions was not associated with the age of the dog. Lenses from young cats (cats (> 4 years old) did not. Glucose concentrations were similar in all lenses incubated in high-glucose medium; however aldose reductase activity was significantly lower in lenses from older cats, compared with lenses from young cats and from dogs. High aldose reductase activity and glucose-related opacities suggest a central role for this enzyme in the pathogenesis of diabetic cataracts in dogs and cats. Because onset of diabetes mellitus usually occurs in cats > 7 years of age, low activity of aldose reductase in lenses of older cats may explain why diabetic cataracts are rare in this species despite hyperglycemia.

  1. Important Questions Of Comparative Studies In Asian Countries

    OpenAIRE

    Pazyura Natalia

    2015-01-01

    The issue of the “identity” of comparative education as a field of study or a discipline has been discussed for decades. Yet a kind of systematic structure that provides the basic principles for a coherent exposition of the field remains open. “Comparative education” is no longer conceived as an imaginary field’s coherence but, rather in terms of distinct branches of comparative and international studies in education and their underlying issues. Such an understanding is fostered through a dee...

  2. Developing a promotional strategy: important questions for social marketing.

    Science.gov (United States)

    Thackeray, Rosemary; Neiger, Brad L; Hanson, Carl L

    2007-10-01

    Health practitioners often use the terms marketing and promotion interchangeably. Yet, promotion is just one element of an overall marketing strategy. To realize the greatest impact there must be a combination of all the marketing components, including product, price, place, and promotion. The purpose of this article is to clarify the role of promotion and describe key elements of developing a promotional strategy within the broader context of a social marketing initiative.

  3. Signs of Bullying: Important Questions for Parents to Ask

    Science.gov (United States)

    ... size, age, political advantage, economic advantage or social advantage. Bullying is common, happening every seven seconds to a child in the U.S. It reaches victims in school and online via social media apps and programs like Instagram, SnapChat, WhatsApp, Burn Note, Whisper, Yik Yak and ...

  4. Important Questions Of Comparative Studies In Asian Countries

    Directory of Open Access Journals (Sweden)

    Pazyura Natalia

    2015-06-01

    Full Text Available The issue of the “identity” of comparative education as a field of study or a discipline has been discussed for decades. Yet a kind of systematic structure that provides the basic principles for a coherent exposition of the field remains open. “Comparative education” is no longer conceived as an imaginary field’s coherence but, rather in terms of distinct branches of comparative and international studies in education and their underlying issues. Such an understanding is fostered through a deepened awareness of the basic problems, and successive solutions, constitutive of the emergence and further conformations of the comparative approach in education and the social sciences. Thus, academic journal publications of the past decade to shape education policy research within an Asia-Pacific context have been analyzed. Facts of increasing research collaboration, growing policy evaluation research, and growing attention to higher education have been presented. Significant difference in research impact and diffusion between Asia-Pacific and American education policy studies has been shown. Perspectives for future research directions in education policy research in an Asia-Pacific context have been suggested.

  5. The question about paleoinformatics

    Science.gov (United States)

    Vartic, Andrei

    2006-12-01

    The author is treating questions about development of informatics in ancient Dacia during Y-th Century B.C. - 2-nd Century A.C. He is introducing a new terminology (paleoinformatics) in view of defining the interests of Daces in numbering, the elementary numbers theory and various aspects of numbers representation. A relation between elementary numbers theory and informatisation has been discussed. A particular interest has been given to calculation of the Circle length/Diameter ratio (number Pi), its calculation by Daces.

  6. Questioning Danish Cartoon Images

    DEFF Research Database (Denmark)

    Bojsen, Heidi

    2007-01-01

    The article discusses the language and satirical cartoons that describe African Danes in the Danish media. Starting with a brief historical overview of the social fonction of satirical cartoons in Denmark since the Reformation, it is discussed whether satire and satirical cartoons actually have s...... Danes today when it is considered demeaning and racist in most other countries. The conclusion does emphatically not plead in favour of law enforced limitations of the freedom of expression, but does question the prevalent "freedom of ignorance" concerning black identities which means...

  7. Generating ethnographic research questions

    DEFF Research Database (Denmark)

    Friberg, Torbjörn

    2015-01-01

    As part of recent complex transformations, it seems that higher educational organisations are being forced to reorganise, standardise and streamline in order to survive in the new political and economic context. How are ethnographers in general going to approach these contemporary phenomena......? By drawing on the conceptual history of anthropology, the aim of this article is to generate ethnographic-oriented research questions concerned with higher education. The first part of the article provides an ethnographic background, while the second part focuses on Paul Willis's reasoning on ethnographic...

  8. Gravitational lensing in a cold dark matter universe

    Science.gov (United States)

    Narayan, Ramesh; White, Simon D. M.

    1988-01-01

    Gravitational lensing due to mass condensations in a biased cold dark matter (CDM) universe is investigated using the Press-Schechter (1974) theory with density fluctuation amplitudes taken from previous N-body work. Under the critical assumption that CDM haloes have small core radii, a distribution of image angular separations for high-z lensed quasars with a peak at about 1 arcsec and a half-width of a factor of about 10. Allowing for selection effects at small angular separations, this is in good agreement with the observed separations. The estimated frequency of lensing is somewhat lower than that observed, but the discrepancy can be removed by invoking amplification bias and by making a small upward adjustment to the density fluctuation amplitudes assumed in the CDM model.

  9. Observations of Cluster Substructure using Weakly Lensed Sextupole Moments

    Energy Technology Data Exchange (ETDEWEB)

    Irwin, John

    2003-08-01

    Since dark matter clusters and groups may have substructure, we have examined the sextupole content of Hubble images looking for a curvature signature in background galaxies that would arise from galaxy-galaxy lensing. We describe techniques for extracting and analyzing sextupole and higher weakly lensed moments. Indications of substructure, via spatial clumping of curved background galaxies, were observed in the image of CL0024 and then surprisingly in both Hubble deep fields. We estimate the dark cluster masses in the deep field. Alternatives to a lensing hypothesis appear improbable, but better statistics will be required to exclude them conclusively. Observation of sextupole moments would then provide a means to measure dark matter structure on smaller length scales than heretofore.

  10. Improvements to the Root Finding Algorithm in VBBinaryLensing

    Science.gov (United States)

    Heintz, Tyler; Hoag, Ava; Bozza, Valerio; Oberst, Thomas

    2018-01-01

    VBBinaryLensing is the leading code for fitting magnification maps to microlensing events by binary lenses, most especially for exoplanet discoveries. The majority of the code’s runtime is devoted to finding roots of a fifth order complex polynomial arising from the binary lens equation. This is currently accomplished via the ZROOTS subroutine, which employs Laguerre’s method. Skowron and Gould’s (2012) algorithm, which employs a combination of Laguerre’s and Newton’s methods, presents the possibility of faster runtimes. We introduce a C++ translation of Skowron and Gould’s algorithm and test it as a replacement for ZROOTS in VBBinaryLensing. We find that this new implementation both reduces the time spent finding roots and makes the code more robust in extreme regimes.

  11. Strong lensing of gravitational waves as seen by LISA.

    Science.gov (United States)

    Sereno, M; Sesana, A; Bleuler, A; Jetzer, Ph; Volonteri, M; Begelman, M C

    2010-12-17

    We discuss strong gravitational lensing of gravitational waves from the merging of massive black hole binaries in the context of the LISA mission. Detection of multiple events would provide invaluable information on competing theories of gravity, evolution and formation of structures and, possibly, constraints on H0 and other cosmological parameters. Most of the optical depth for lensing is provided by intervening massive galactic halos, for which wave optics effects are negligible. Probabilities to observe multiple events are sizable for a broad range of formation histories. For the most optimistic models, up to ≲ 4 multiple events with a signal to noise ratio ≳ 8 are expected in a 5-year mission. Chances are significant even for conservative models with either light (≲ 60%) or heavy (≲ 40%) seeds. Because of lensing amplification, some intrinsically too faint signals are brought over threshold (≲ 2 per year).

  12. Feedback as the source of imperfection in lossy perfect lenses

    Science.gov (United States)

    Rosenblatt, Gilad; Bartal, Guy; Orenstein, Meir

    2016-02-01

    The major barrier to realizing a perfect lens with left-handed materials is perceived to be their intrinsic loss. Here we show that only specific designs of perfect lenses are limited by loss—those in which material loss is translated to internal feedback. The asymptotically uniform transmission required for perfect lensing is hindered by such feedback, which generates resonances that lead to a spatial cutoff in the lens transmission. Moreover, uniform transmission and its resonant deterioration stem from completely separate classes of modal excitations. A perfect lens made of lossy left-handed materials is therefore not forbidden in principle. Pursuing perfect lens designs that avoid internal feedback offers a path towards realization of practical perfect lenses.

  13. Computerized calculation scheme for toric intraocular lenses.

    Science.gov (United States)

    Langenbucher, Achim; Seitz, Berthold

    2004-06-01

    While a number of intraocular lens (IOL) power prediction formulae are well established for determination of spherical lenses, no common strategy has been published for the computation of toric IOLs. The purpose of this study is to describe a paraxial computing scheme for tracing an axial pencil of rays through the 'optical system eye' containing astigmatic refractive surfaces with their axes at random. The capabilities of this computing scheme are demonstrated with clinical examples. Based on a schematic model eye with spherocylindric surfaces, we use two alternative notations for description of vergences or prescriptions: (1) standard notation (refraction in both cardinal meridians and axis), and (2) component notation (spherical equivalent and cylindric component in 0 degrees and 45 degrees. Refractive surfaces are added to the vergence in component notation, whereas the transformation of the vergence through media is performed in the standard notation for both cardinal meridians. For calculation of the toric lens implant, a pencil of rays is traced through the spectacle and the cornea to the estimated lens position as well as backwards from the retina to the estimated lens position. For calculation of residual spectacle refraction, a pencil of rays is traced backwards from the retina through the toric lens implant and the cornea to the spectacle plane. In example 1 we calculate a 'thin toric lens' for compensation of a corneal astigmatism to achieve a spherical target refraction. In example 2 we compute a 'thick toric lens', which has to compensate for an oblique corneal astigmatism and rotate the spectacle cylinder to the against the rule position to enhance near vision. In example 3 we estimate the residual refraction at the corneal plane after implantation of a thick toric lens, when the cylinder of the lens implant is compensating the corneal cylinder in part and the axis of implantation is not fully aligned with the axis of the corneal astigmatism. This

  14. Inferring Domain Plans in Question-Answering

    National Research Council Canada - National Science Library

    Pollack, Martha E

    1986-01-01

    The importance of plan inference in models of conversation has been widely noted in the computational-linguistics literature, and its incorporation in question-answering systems has enabled a range...

  15. Trick questions: cosmopolitan hospitality

    Directory of Open Access Journals (Sweden)

    Eleanor Byrne

    2013-08-01

    Full Text Available Byrne’s paper consists of two parallel texts. The first explores the limits of cosmopolitanism in practice, taking as its subject the Life in the UK Citizenship Test, inaugurated under the Labour Government in 2005. It argues that the test exemplifies the predicament of all attempts at cosmopolitan hospitality as unconditional welcoming, through a discussion of the relation between questioning and welcoming the stranger. Establishing the relationship between cosmopolitanism and hospitality as envisaged in Derrida’s reading of Kant it asks what kind of cosmopolitan hospitality is either possible or desirable by exploring what Derrida calls the ‘perversions’ inherent in the structures of hospitality. It focuses on the concept of the ‘trick questions’ that the state asks the foreigner observed by Derrida in his reading of The Apology of Socrates; questions that seem to invite answers but foreclose the possibilities of a free response. The second text asks how this logic that Derrida identifies can be pushed or coaxed into new ways of addressing the perceived threats of ‘unconditional’ hospitality through a reading of ‘unconditional hospitality’ as queer in the work of Tove Jansson.

  16. Daily disposable contact lenses versus spectacles in teenagers.

    Science.gov (United States)

    Plowright, Andrew J; Maldonado-Codina, Carole; Howarth, Gillian F; Kern, Jami; Morgan, Philip B

    2015-01-01

    To compare clinical and subjective quality-of-life (QoL) data for teenagers wearing daily disposable contact lenses or spectacles. This open-label study randomized subjects (aged 13 to 19 years) with no previous contact lens wear experience to nelfilcon A (DAILIES AquaComfort Plus) contact lenses or spectacles for 6 months. A full clinical workup, as well as subjective QoL measures using the Pediatric Refractive Error Profile and Quality of Life Impact of Refractive Correction questionnaires, was conducted at baseline and at week 4 and months 3 and 6, with an additional study visit at week 2 for subjects randomized to wear contact lenses. A total of 110 teenagers were enrolled in the study; 13 discontinued before study completion, 10 (17.5%) from the contact lens group and 3 (5.7%) from the spectacle group (p = 0.04). Visual acuity was good for both groups at all study visits. Biomicroscopy assessments were similar at baseline for both groups. Significant differences in Pediatric Refractive Error Profile responses were noted between vision correction groups across visits for appearance (p teenagers had a more positive attitude toward comfort, vision, and safety with contact lenses. No serious adverse events were reported during the study. The daily disposable lenses used in this study are suitable for vision correction for teenagers, offering improvements in QoL measures during the first month of wear, including appearance, satisfaction, activities, and peer perceptions, without negatively impacting vision or eye health. Teenagers were able to handle contact lenses with the same amount of confidence as spectacles.

  17. Questions and Answers about Psychosis

    Science.gov (United States)

    ... Glossary RAISE Questions and Answers Questions & Answers about Psychosis What is psychosis? What causes psychosis? How common ... we learn from RAISE-IES? Questions & Answers About Psychosis Q: What is psychosis? A: The word psychosis ...

  18. Strong Lensing Science Results from the Hyper Suprime-Cam Survey

    Science.gov (United States)

    Wong, Kenneth; HSC SSP Strong Lens Working Group

    2018-01-01

    Strong gravitational lenses are valuable objects for studying galaxy structure and cosmology. Lensing is a unique probe of the dark matter structure of galaxies, groups, and clusters, as well as an independent tool for constraining cosmological parameters. Lensing also magnifies the background source population, allowing for detailed studies of their properties at high resolution. However, strong lenses are rare and difficult to find, requiring deep wide-area high-resolution imaging surveys. With data from the ongoing Hyper Suprime-Cam (HSC) Subaru Strategic Program, we have discovered over 100 new strong lenses at the galaxy and group scale to expand the sample of lensing systems, particularly at redshifts z > 0.5, where there have previously been relatively few known lenses. We present a summary of the latest strong lensing science results from the HSC survey data taken through the S17A semester.

  19. 21 CFR 801.410 - Use of impact-resistant lenses in eyeglasses and sunglasses.

    Science.gov (United States)

    2010-04-01

    ... frequency of eye injuries resulting from the shattering of ordinary crown glass lenses indicates that the... multifocal, bioconcave, myodisc and minus lenticular, custom laminate and cemented assembly lenses shall be...

  20. Shadows and strong gravitational lensing: a brief review

    Science.gov (United States)

    Cunha, Pedro V. P.; Herdeiro, Carlos A. R.

    2018-04-01

    For ultra compact objects, light rings and fundamental photon orbits (FPOs) play a pivotal role in the theoretical analysis of strong gravitational lensing effects, and of BH shadows in particular. In this short review, specific models are considered to illustrate how FPOs can be useful in order to understand some non-trivial gravitational lensing effects. This paper aims at briefly overviewing the theoretical foundations of these effects, touching also some of the related phenomenology, both in general relativity and alternative theories of gravity, hopefully providing some intuition and new insights for the underlying physics, which might be critical when testing the Kerr black hole hypothesis.

  1. Application and System Design of Elastomer Based Optofluidic Lenses

    Science.gov (United States)

    Savidis, Nickolaos

    Adaptive optic technology has revolutionized real time correction of wavefront aberrations. Optofluidic based applied optic devices have offered an opportunity to produce flexible refractive lenses in the correction of wavefronts. Fluidic lenses have superiority relative to their solid lens counterparts in their capabilities of producing tunable optical systems, that when synchronized, can produce real time variable systems with no moving parts. We have developed optofluidic fluidic lenses for applications of applied optical devices, as well as ophthalmic optic devices. The first half of this dissertation discusses the production of fluidic lenses as optical devices. In addition, the design and testing of various fluidic systems made with these components are evaluated. We begin with the creation of spherical or defocus singlet fluidic lenses. We then produced zoom optical systems with no moving parts by synchronizing combinations of these fluidic spherical lenses. The variable power zoom system incorporates two singlet fluidic lenses that are synchronized. The coupled device has no moving parts and has produced a magnification range of 0.1 x to 10 x or a 20 x magnification range. The chapter after fluidic zoom technology focuses on producing achromatic lens designs. We offer an analysis of a hybrid diffractive and refractive achromat that offers discrete achromatized variable focal lengths. In addition, we offer a design of a fully optofluidic based achromatic lens. By synchronizing the two membrane surfaces of the fluidic achromat we develop a design for a fluidic achromatic lens. The second half of this dissertation discusses the production of optofluidic technology in ophthalmic applications. We begin with an introduction to an optofluidic phoropter system. A fluidic phoropter is designed through the combination of a defocus lens with two cylindrical fluidic lenses that are orientated 45° relative to each other. Here we discuss the designs of the fluidic

  2. Gravitational Lensing in the metric theory proposed by Sobouti

    Science.gov (United States)

    Bernal, Tula; Mendoza, Sergio

    2008-12-01

    Recently, Y. Sobouti (2007) has provided a metric theory f(R) that can account for certain dynamical anomalies observed in spiral galaxies. Mendoza & Rosas-Guevara (2007) have shown that in this theory there is an extra-bending as compared to standard general relativity. In the present work we have developed in more specific detail this additional lensing effect and we have made evaluations of the α parameter used in the model adjusting the theory to observations in X-rays of 13 clusters of galaxies with gravitational lensing ([6]).

  3. Probing dark energy with lensing magnification in photometric surveys.

    Science.gov (United States)

    Schneider, Michael D

    2014-02-14

    I present an estimator for the angular cross correlation of two tracers of the cosmological large-scale structure that utilizes redshift information to isolate separate physical contributions. The estimator is derived by solving the Limber equation for a reweighting of the foreground tracer that nulls either clustering or lensing contributions to the cross correlation function. Applied to future photometric surveys, the estimator can enhance the measurement of gravitational lensing magnification effects to provide a competitive independent constraint on the dark energy equation of state.

  4. From Questions to Queries

    Directory of Open Access Journals (Sweden)

    M. Drlík

    2007-12-01

    Full Text Available The extension of (Internet databases forceseveryone to become more familiar with techniques of datastorage and retrieval because users’ success often dependson their ability to pose right questions and to be able tointerpret their answers. University programs pay moreattention to developing database programming skills than todata exploitation skills. To educate our students to become“database users”, the authors intensively exploit supportivetools simplifying the production of database elements astables, queries, forms, reports, web pages, and macros.Videosequences demonstrating “standard operations” forcompleting them have been prepared to enhance out-ofclassroomlearning. The use of SQL and other professionaltools is reduced to the cases when the wizards are unable togenerate the intended construct.

  5. 1. Methodological Questions

    Directory of Open Access Journals (Sweden)

    Luca Arcari (a cura di

    2015-06-01

    Full Text Available The first part of this monographic section aims at analysing some methodological questions concerning identities, ethnicities, collectivities and religions, starting from the academic debate occurred between historians and anthropologists since the last decades of Twentieth Century, considering its reception especially for the study of ethnicity and collective and/or (so-called religious identities in the cultural context of ancient Greece. Another aspect of such a methodological section deals with the innovative approach inaugurated by the so-called “School of Wien” in the study of ethnic identity-constructions, especially analysing the relationships with Biblical texts as well as their multiform receptions between late-antiquity and early medieval period.

  6. Biofuels - 5 disturbing questions

    International Nuclear Information System (INIS)

    Legalland, J.P.; Lemarchand, J.L.

    2008-01-01

    Initially considered as the supreme weapon against greenhouse gas emissions, biofuels are today hold responsible to all harms of the Earth: leap of agriculture products price, deforestation, food crisis. Considered some time ago as the perfect clean substitute to petroleum, biofuels are now suspected to have harmful effects on the environment. Should it be just an enormous technical, environmental and human swindle? Should we abandon immediately biofuels to protect the earth and fight the threatening again starvation? Should we wait for the second generation of efficient biofuels, made from non food-derived products and cultivation wastes? This book analyses this delicate debate through 5 main questions: do they starve the world? Are they a clean energy source? Do they contribute to deforestation? Are they economically practicable? Is the second generation ready? (J.S.)

  7. Cellular proliferation and regeneration following tissue damage. Progress report. [X radiation; rabbit lenses

    Energy Technology Data Exchange (ETDEWEB)

    Harding, C.V.

    1977-01-01

    Studies were conducted on the following research projects: effects of x radiation on rabbit lenses; DNA synthesis and mitosis in cultured lenses; serum dependency and actinomycin D sensitivity; changes in ultrastructure; injury-induced growth of vascular endothelium; corneal neovascularization following injury; and human cataractous lenses. (HLW)

  8. High Quality Liquid Crystal Tunable Lenses and Optimization with Floating Electrodes

    Science.gov (United States)

    Li, Liwei

    2013-01-01

    In addition to the display application, Liquid Crystals (LC) can be very useful in other applications such as beam steering, tunable lenses, etc. Electro-optical LC tunable lenses have been considered as an alternative to conventional glass lenses because of their ability to change their focal length with the application of a control voltage, as…

  9. Big questions about the universe

    Science.gov (United States)

    Stavinschi, Magda

    2011-06-01

    Astronomy is not only a branch of science but also an important part of the culture and civilisations of peoples. Starting with archeoastronomy to the present day, it has always contributed to a better understanding of life, of humanity. After 400 years of modern astronomy, it still addresses major problems such as: Why there is something rather than nothing? Why is nature comprehensible to humans? How is cosmos related to humanity? Do multiverses exist? Is there life on other planets? Are we alone in the universe? Does the universe have a beginning? If so, what does it mean? How did the universe originate? All these questions are a challenge for interdisciplinary and transdisciplinary investigations, for philosophers, physicists, cosmologists, mathematicians, theologians. The new insights gained by pursuing in depth these common investigations will shape the society we live in and have important consequences on the future we are creating.

  10. Formation of magmatic brine lenses via focussed fluid-flow beneath volcanoes

    Science.gov (United States)

    Afanasyev, Andrey; Blundy, Jon; Melnik, Oleg; Sparks, Steve

    2018-03-01

    Many active or dormant volcanoes show regions of high electrical conductivity at depths of a few kilometres beneath the edifice. We explore the possibility that these regions represent lenses of high-salinity brine separated from a single-phase magmatic fluid containing H2O and NaCl. Since chloride-bearing fluids are highly conductive and have an exceptional capacity to transport metals, these regions can be an indication of an active hydrothermal ore-formation beneath volcanoes. To investigate this possibility we have performed hydrodynamic simulations of magma degassing into permeable rock. In our models the magma source is located at 7 km depth and the fluid salinity approximates that expected for fluids released from typical arc magmas. Our model differs from previous models of a similar process because it is (a) axisymmetric and (b) includes a static high-permeability pathway that links the magma source to the surface. This pathway simulates the presence of a volcanic conduit and/or plexus of feeder dykes that are typical of most volcanic systems. The presence of the conduit leads to a number of important hydrodynamic consequences, not observed in previous models. Importantly, we show that an annular brine lens capped by crystallised halite is likely to form above an actively degassing sub-volcanic magma body and can persist for more than 250 kyr after degassing ceases. Parametric analysis shows that brine lenses are more prevalent when the fluid is released at temperatures above the wet granite solidus, when magmatic fluid salinity is high, and when the high-permeability pathway is narrow. The calculated depth, form and electrical conductivity of our modelled system shares many features with published magnetotelluric images of volcano subsurfaces. The formation and persistence of sub-volcanic brine lenses has implications for geothermal systems and hydrothermal ore formation, although these features are not explored in the presented model.

  11. OT2_smalhotr_3: Herschel Extreme Lensing Line Observations (HELLO)

    Science.gov (United States)

    Malhotra, S.

    2011-09-01

    We request 59.8 hours of Herschel time to observe 20 normal star-forming galaxies in the [CII] 158 micron and [OI] 63 micron lines. These galaxies lie at high redshift (1lensing, but have modest star formation rates. Therefore they represent our best chance of studying star formation and the interstellar medium in typical, common galaxies at this epoch. Redshift 1 to 3 spans the peak of both star formation activity and black hole accretion in active galactic nuclei-- a period that was crucial in shaping our modern universe. Most of this redshift range is inaccesible to ground-based observations of [CII], [OI], or both. Herschel offers the unique opportunity to study both lines with high sensitivity throughout this epoch (using HIFI for [CII] and PACS for [OI]). These two lines are the main cooling lines of the atomic medium. By measuring their fluxes, we will measure (1) the cooling efficiency of gas, (2) gas densities and temperatures near starforming regions, and (3) gas pressures, which are important to drive the winds that provide feedback to starformation processes. By combining the proposed observations with existing multiwavelength data on these objects, we will obtain as complete a picture of galaxy-scale star formation and ISM physical conditions at high redshifts as we have at z=0. Then perhaps we can understand why star formation and AGN activity peaked at this epoch. In Herschel cycle OT1, 49 high redshift IR luminous galaxies were approved for spectroscopy, but only two so-called normal galaxies were included. This is an imbalance that should be corrected, to balance Herschel's legacy.

  12. Assessing Question Quality Using NLP

    Science.gov (United States)

    Kopp, Kristopher J.; Johnson, Amy M.; Crossley, Scott A.; McNamara, Danielle S.

    2017-01-01

    An NLP algorithm was developed to assess question quality to inform feedback on questions generated by students within iSTART (an intelligent tutoring system that teaches reading strategies). A corpus of 4575 questions was coded using a four-level taxonomy. NLP indices were calculated for each question and machine learning was used to predict…

  13. Strong Gravitational Lensing in a Brane-World Black Hole

    Science.gov (United States)

    Li, GuoPing; Cao, Biao; Feng, Zhongwen; Zu, Xiaotao

    2015-09-01

    Adopting the strong field limit approach, we investigated the strong gravitational lensing in a Brane-World black hole, which means that the strong field limit coefficients and the deflection angle in this gravitational field are obtained. With this result, it can be said with certainly that the strong gravitational lensing is related to the metric of gravitational fields closely, the cosmology parameter α and the dark matter parameter β come from the Brane-World black hole exerts a great influence on it. Comparing with the Schwarzschild-AdS spacetime and the Schwarzschild-XCMD spacetime, the parameters α, β of black holes have the similar effects on the gravitational lensing. In some way, we infer that the real gravitational fields in our universe can be described by this metric, so the results of the strong gravitational lensing in this spacetime will be more reasonable for us to observe. Finally, it has to be noticed that the influence which the parameters α, β exerted on the main observable quantities of this gravitational field is discussed.

  14. Energy-Efficient Optical Signal Processing Using Optical Time Lenses

    DEFF Research Database (Denmark)

    Oxenløwe, Leif Katsuo; Galili, Michael; Mulvad, Hans Christian Hansen

    2015-01-01

    . Combining time lenses into telescopic arrangements allows for more advanced signal processing, such as temporal or spectral compression or magnification. A spectral telescope may for instance allow for conversion of OFDM signals to DWDM-like signals, which can be separated passively, i.e. without additional...

  15. The Perspective Effect of Wide-Angle Lenses in Laparoscopes

    NARCIS (Netherlands)

    Wentink, M.; Fischer, H.; Dankelman, J.; Stassen, L.P.S.; Wieringa, P.A.

    2002-01-01

    Purpose: To evaluate the effect of perspective distortion of wide-angle lenses in laparoscopes on hand-eye coordination during endoscopic manipulation. Methods: Sixteen subjects repeatedly performed a standardized positioning task in a pelvi-trainer under two conditions. The subjects had no prior

  16. How to Measure Dark Energy with LSST's Strong Gravitational Lenses

    Science.gov (United States)

    Marshall, Philip J.; Treu, T.; Brunner, R. J.; Strong Lensing, LSST; Dark Energy Science Collaborations

    2013-01-01

    Strong gravitational lensing is sensitive to dark energy (DE) via the combinations of angular diameter distances that appear in model predictions of the lens strength. Lenses with variable sources offer the most promise: the corresponding time delay distance has recently been shown to be measurable to 5% precision. Large samples of lensed quasars and supernovae will allow internal degeneracy-breaking and so enable the most direct access to the DE parameters, while multiple source-plane, compound lens systems may provide an alternative, complementary, H0-free probe. Its wide field survey and high cadence will enable LSST to provide a sample of several thousand measured time delays, two orders of magnitude larger than the current sample, and allow an independent, competitive Stage IV DE parameter measurement to be made. However, practical problems to be solved include: lens detection (which may be very sensitive to image quality and deblender performance); image and lightcurve modelling (which could be both CPU and manual labor-intensive); obtaining and analyzing high resolution spectro-imaging follow-up data; and interpreting the whole sample of lenses in the context of the well-studied subset.

  17. Single-molecule microscopy using silicone oil immersion objective lenses

    NARCIS (Netherlands)

    Hink, M.

    2012-01-01

    Microscopy techniques capable of detecting individual molecules and providing quantitative data have the potential to offer great biological insight; however, such approaches require the efficient capture of light. Here, Mark Hink explains how the use of new silicone oil immersion objective lenses

  18. Planck-Scale Dual-Curvature Lensing and Spacetime Noncommutativity

    Directory of Open Access Journals (Sweden)

    Giovanni Amelino-Camelia

    2017-01-01

    Full Text Available It was recently realized that Planck-scale momentum-space curvature, which is expected in some approaches to the quantum-gravity problem, can produce dual-curvature lensing, a feature which mainly affects the direction of observation of particles emitted by very distant sources. Several gray areas remain in our understanding of dual-curvature lensing, including the possibility that it might be just a coordinate artifact and the possibility that it might be in some sense a by-product of the better studied dual-curvature redshift. We stress that data reported by the IceCube neutrino telescope should motivate a more vigorous effort of investigation of dual-curvature lensing, and we observe that studies of the recently proposed “ρ-Minkowski noncommutative spacetime” could be valuable from this perspective. Through a dedicated ρ-Minkowski analysis, we show that dual-curvature lensing is not merely a coordinate artifact and that it can be present even in theories without dual-curvature redshift.

  19. Characterisation of adaptive fluidic silicone-membrane lenses

    CSIR Research Space (South Africa)

    Schneider, F

    2010-03-01

    Full Text Available The authors compare the performance and optical quality of two types of adaptive fluidic silicone-membrane lenses. The membranes feature either a homogeneous thickness, or they are shaped resulting in an inhomogeneous cross-section. The lens systems...

  20. Microbiological study of disposable soft contact lenses after photorefractive keratectomy.

    Science.gov (United States)

    Dantas, P E; Nishiwaki-Dantas, M C; Ojeda, V H; Holzchuh, N; Mimica, L J

    2000-01-01

    To evaluate the bacterial contamination of bandage disposable soft contact lenses used in patients following photorefractive keratectomy (PRK) and to correlate our findings with clinical data. Forty-six patients (81 eyes) underwent PRK. Immediately after each procedure, disposable soft contact lenses were positioned with sterile forceps. After 3 days, the lenses were removed in a sterile manner, placed in sterile Eppendorf pipettes containing 8 mL of enriched brain heart infusion broth, and analyzed for microbial contamination. Seven positive cultures were found: six gram positive cocci (7.4%) and one gram negative bacillus (1.2%). There was no clinical correlation with these findings. Isolated microorganisms were similar to those described in the literature as agents of bacterial keratitis and are components of the normal ocular flora. Klebsiela pneumoniae--considered an occasional or transient flora--was the exception. All isolated microorganisms but K. pneumoniae were sensitive to most of the antibiotics tested. Our findings suggest that the risk of infectious keratitis after PRK related to soft contact lens wear for 3 days seems to be low, which may be because lenses were not manipulated by the patient during the wearing period, and the postoperative antibiotic regimen was strictly followed by patients. However, care should be taken to instruct patients in proper lens care practices to reduce the risk of bacterial keratitis in contact lens wear following PRK.

  1. Cylindrical diffractive lenses recorded on PVA/AA photopolymers

    Science.gov (United States)

    Fernández, R.; Gallego, S.; Márquez, A.; Navarro-Fuster, V.; Francés, J.; Neipp, C.; Beléndez, A.; Pascual, I.

    2016-04-01

    Photopolymers are optical recording materials appealing for many different applications such as holography, data storage, interconnectors, solar concentrations, or wave-guides fabrication. Recently the capacity of photopolymers to record diffractive optical elements (DOE's) has been investigated. Different authors have reported proposes to record DOE like fork gratings, photonics structures, lenses, sinusoidal, blazed or fork gratings. In these experiments there are different experimental set-ups and different photopolymers. In this work due to the improvement in the spatial light modulation technology together with the photopolymer science we propose a recording experimental system of DOE using a Liquid Cristal based on Silicon (LCoS) display as a master to store complex DOE like cylindrical lenses. This technology permits us an accurate control of the phase and the amplitude of the recording beam, with a very small pixel size. The main advantage of this display is that permit us to modify the DOE automatically, we use the software of the LCoS to send the voltage to each pixel In this work we use a photopolymer composed by acrylamide (AA) as polymerizable monomer and polyvinyl alcohol (PVA). We use a coverplated and index matched photopolymer to avoid the influence of the thickness variation on the transmitted light. In order to reproduce the material behaviour during polymerization, we have designed our model to simulate cylindrical lenses and used Fresnel propagation to simulate the light propagation through the DOE and analyze the focal plane and the properties of the recorded lenses.

  2. Active Learning Environment with Lenses in Geometric Optics

    Science.gov (United States)

    Tural, Güner

    2015-01-01

    Geometric optics is one of the difficult topics for students within physics discipline. Students learn better via student-centered active learning environments than the teacher-centered learning environments. So this study aimed to present a guide for middle school teachers to teach lenses in geometric optics via active learning environment…

  3. UK Higher Education Viewed through the Marketization and Marketing Lenses

    Science.gov (United States)

    Nedbalová, Eva; Greenacre, Luke; Schulz, John

    2014-01-01

    This paper uses the Economic Market mechanisms and the 4P Marketing Mix as lenses to review the context of UK higher education (HE) and to explore the relationship between the market and marketing disciplines and practice. Four Economic Market mechanisms--autonomy, competition, price and information--are contrasted with the four Ps of marketing:…

  4. Disposable contact lenses vs. contact lens maintenance for extended wear.

    Science.gov (United States)

    Josephson, J E; Caffery, B E; Campbell, I; Slomovic, A R

    1990-01-01

    We compared a disposable extended wear contact lens modality with conventional extended wear over a 6-week period. To do so, we refit 31 patients who had successfully worn conventional extended wear contact lenses for more than 1 year. One eye was fit with the AcuvueR disposable contact lens, and a new extended wear lens of the type the patient had been wearing was placed on the other eye. At weekly intervals the disposable lens was discarded and a new disposable lens inserted. At the same time, the conventional lens on the fellow eye was cleaned, disinfected, and reinserted. After 6 weeks the ocular response, subjective impressions, and condition of the lenses in the two eyes were compared. Both lenses were then cultured. Three subjects had to discontinue disposable lens wear because of adverse reactions to trapped cellular debris and corneal microcysts. Although the results were not statistically significant, the Acuvue lens appeared to perform better than or equal to the conventional lens in biomicroscopic observation, visual acuity measurement, and subjective patient preference. Eighty-seven percent of patients preferred to continue with the disposable system. There were no differences found in the type or degree of microbial contamination of the lenses.

  5. Jupiter Scleral Lenses: the UC Davis Eye Center experience.

    Science.gov (United States)

    Pecego, Mariana; Barnett, Melissa; Mannis, Mark J; Durbin-Johnson, Blythe

    2012-05-01

    The aim of this study was to evaluate both the indications for and results of fitting the Jupiter Scleral Lens in patients with corneal abnormalities. This was a retrospective case review of 63 patients (107 eyes) fitted with scleral lenses between October 2009 and March 2011 at the UC Davis Eye Center. Sixty-three percent of 107 eyes were in patients with keratoconus. Other conditions included high postkeratoplasty astigmatism and corneal scarring. The improvement in best-corrected visual acuity compared with previous contact lens or glasses correction was a mean gain of 3.5 Snellen lines (SD=2.6). Seventy-eight percent of patients found the scleral lenses to be comfortable or comfortable. Twenty-five eyes discontinued the wear after at least 3 months. Jupiter Scleral lenses are a good alternative for patients with corneal abnormalities and for those who failed other types of lens rehabilitation. Seventy-seven percent of eyes fit with Jupiter Scleral Lenses were still wearing after a follow-up of 3 months.

  6. Galaxy-galaxy lensing estimators and their covariance properties

    Science.gov (United States)

    Singh, Sukhdeep; Mandelbaum, Rachel; Seljak, Uroš; Slosar, Anže; Vazquez Gonzalez, Jose

    2017-11-01

    We study the covariance properties of real space correlation function estimators - primarily galaxy-shear correlations, or galaxy-galaxy lensing - using SDSS data for both shear catalogues and lenses (specifically the BOSS LOWZ sample). Using mock catalogues of lenses and sources, we disentangle the various contributions to the covariance matrix and compare them with a simple analytical model. We show that not subtracting the lensing measurement around random points from the measurement around the lens sample is equivalent to performing the measurement using the lens density field instead of the lens overdensity field. While the measurement using the lens density field is unbiased (in the absence of systematics), its error is significantly larger due to an additional term in the covariance. Therefore, this subtraction should be performed regardless of its beneficial effects on systematics. Comparing the error estimates from data and mocks for estimators that involve the overdensity, we find that the errors are dominated by the shape noise and lens clustering, which empirically estimated covariances (jackknife and standard deviation across mocks) that are consistent with theoretical estimates, and that both the connected parts of the four-point function and the supersample covariance can be neglected for the current levels of noise. While the trade-off between different terms in the covariance depends on the survey configuration (area, source number density), the diagnostics that we use in this work should be useful for future works to test their empirically determined covariances.

  7. On an illusion of superluminal velocities produced by gravitational lenses

    International Nuclear Information System (INIS)

    Ingel, L.Kh.

    1981-01-01

    It is noted that gravitational lenses, by focusing the radiation of an object, increase the angle which it subtends. This in turn produces the illusion of an increase in velocities at right angles to the line of sight. Preliminary estimates are made which indicate a rather high probability of strong distortion of the observed velocities

  8. Thermal lensing measurement from the coefficient of defocus aberration

    CSIR Research Space (South Africa)

    Bell, Teboho

    2016-03-01

    Full Text Available geometrical method to alleviate irregularities. Figure 4: Unstable plano-parallel laser resonator used to determine thermally induced lensing. Figure 3: (a) The graph of the transmitted power against the input pump power. (b) Nd: YAG cystal pumped by a...

  9. Galaxy number counts and implications for strong lensing

    NARCIS (Netherlands)

    Fassnacht, C. D.; Koopmans, L. V. E.; Wong, K. C.

    We compare galaxy number counts in Advanced Camera for Surveys (ACS) fields containing moderate-redshift (0.2 lenses with those in two control samples: (1) the first square degree of the COSMOS survey, comprising 259 ACS fields and (2) 20 ‘pure-parallel’ fields randomly

  10. Ultraviolet radiation for the sterilization of contact lenses.

    Science.gov (United States)

    Gritz, D C; Lee, T Y; McDonnell, P J; Shih, K; Baron, N

    1990-01-01

    Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials were minimally affected by exposure to 300 hours of UV-B. Ultraviolet light is an effective germicidal agent but is injurious to soft lens polymers; its possible utility in the sterilization of RGP lenses and lens cases deserves further study.

  11. Comparison of objective lenses for multiphoton microscopy in turbid samples.

    Science.gov (United States)

    Singh, Avtar; McMullen, Jesse D; Doris, Eli A; Zipfel, Warren R

    2015-08-01

    Optimization of illumination and detection optics is pivotal for multiphoton imaging in highly scattering tissue and the objective lens is the central component in both of these pathways. To better understand how basic lens parameters (NA, magnification, field number) affect fluorescence collection and image quality, a two-detector setup was used with a specialized sample cell to separate measurement of total excitation from epifluorescence collection. Our data corroborate earlier findings that low-mag lenses can be superior at collecting scattered photons, and we compare a set of commonly used multiphoton objective lenses in terms of their ability to collect scattered fluorescence, providing guidance for the design of multiphoton imaging systems. For example, our measurements of epi-fluorescence beam divergence in the presence of scattering reveal minimal beam broadening, indicating that often-advocated over-sized collection optics are not as advantageous as previously thought. These experiments also provide a framework for choosing objective lenses for multiphoton imaging by relating the results of our measurements to various design parameters of the objectives lenses used.

  12. Weak Lensing by Galaxy Troughs in DES Science Verification Data

    Energy Technology Data Exchange (ETDEWEB)

    Gruen, D. [Ludwig Maximilian Univ., Munich (Germany); Max Planck Inst. for Extraterrestrial Physics, Garching (Germany). et al.

    2015-09-29

    We measure the weak lensing shear around galaxy troughs, i.e. the radial alignment of background galaxies relative to underdensities in projections of the foreground galaxy field over a wide range of redshift in Science Verification data from the Dark Energy Survey. Our detection of the shear signal is highly significant (10σ–15σ for the smallest angular scales) for troughs with the redshift range z ϵ [0.2, 0.5] of the projected galaxy field and angular diameters of 10 arcmin…1°. These measurements probe the connection between the galaxy, matter density, and convergence fields. By assuming galaxies are biased tracers of the matter density with Poissonian noise, we find agreement of our measurements with predictions in a fiducial Λ cold dark matter model. Furthermore, the prediction for the lensing signal on large trough scales is virtually independent of the details of the underlying model for the connection of galaxies and matter. Our comparison of the shear around troughs with that around cylinders with large galaxy counts is consistent with a symmetry between galaxy and matter over- and underdensities. In addition, we measure the two-point angular correlation of troughs with galaxies which, in contrast to the lensing signal, is sensitive to galaxy bias on all scales. Finally, the lensing signal of troughs and their clustering with galaxies is therefore a promising probe of the statistical properties of matter underdensities and their connection to the galaxy field.

  13. Ultraviolet radiation for the sterilization of contact lenses

    International Nuclear Information System (INIS)

    Gritz, D.C.; Lee, T.Y.; McDonnell, P.J.; Shih, K.; Baron, N.

    1990-01-01

    Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials were minimally affected by exposure to 300 hours of UV-B. Ultraviolet light is an effective germicidal agent but is injurious to soft lens polymers; its possible utility in the sterilization of RGP lenses and lens cases deserves further study

  14. Ultraviolet radiation for the sterilization of contact lenses

    Energy Technology Data Exchange (ETDEWEB)

    Gritz, D.C.; Lee, T.Y.; McDonnell, P.J.; Shih, K.; Baron, N. (Univ. of Southern California School of Medicine, Los Angeles (USA))

    1990-10-01

    Two sources of ultraviolet (UV) radiation with peak wavelengths in the UV-C or UV-B ranges were compared for their ability to sterilize contact lenses infected with Pseudomonas aeruginosa, Streptococcus pneumoniae, Acanthamoeba castellani, Candida albicans, and Aspergillus niger. Also examined was the effect of prolonged UV light exposure on soft and rigid gas permeable (RGP) contact lenses. The UV-C lamp (253.7 nm, 250 mW/cm2 at 1 cm) was germicidal for all organisms within 20 minutes but caused destruction of the soft lens polymers within 6 hours of cumulative exposure. UV-C caused damage to RGP lenses in less than 100 hours. The UV-B lamp (290-310 nm, 500 mW/cm2 at 1 cm) was germicidal for all organisms tested (except Aspergillus) with a 180-minute exposure and caused less severe changes in the soft lens polymers than did the UV-C lamp, although cumulative exposure of 300 hours did substantially weaken the soft lens material. RGP materials were minimally affected by exposure to 300 hours of UV-B. Ultraviolet light is an effective germicidal agent but is injurious to soft lens polymers; its possible utility in the sterilization of RGP lenses and lens cases deserves further study.

  15. 101 questions about energy

    International Nuclear Information System (INIS)

    Furfari, S.

    2009-01-01

    Today, energy in the center of the world events. People get swamped with information about energy, environment, energy saving or renewable energy sources. However, the solutions proposed are still in the centre of debates and no consensus exists which allows to define a clear policy: nuclear energy or wind power? Solar energy or biomass fuels? And what about the meaning of the expression 'clean coal'? And why oil prices go up and down while it is said that the resource is close to exhaustion? Mass media are trying to tell us that 'urgency is here', mainly because of the climatic threat of greenhouse gases and because of a world economy totally dependent of politically unstable areas, like Middle East, Africa or Caucasus, but with huge oil and gas resources. And what about Europe, and what about all this gas in Russia? It is hard for a non-specialist to find his way in this complex domain. This is the aim of this book which has opted for the non-politically correct attitude to answer 101 key-questions about the energy topic: Europe's security of supply, energy geopolitics, oil future, energy crises, sustainable development etc. (J.S.)

  16. Une question interdite

    Directory of Open Access Journals (Sweden)

    Pierre Legendre

    2003-01-01

    Full Text Available Is legal history a left-over or is it waiting for a takeover bid (just like a company in serious trouble which would allow the expression of new analyses and outlines for a better understanding of the contemporary western world? Its propositions of erudition, are they just interesting for small academic circles, or could they open a new pathway for fundamental reflections on the phenomenon of norms in general and the structure of its evolution in the special case of norm-production coming from Roman Christianity? And what is the significance of the idea of »legal tradition«, an idea forged in Western Europe, within the framework of a presumed global westernization without any counter-balance? The essay discusses the illegibility of legal history in today’s culture. Under the well reflected motto »The Forbidden Question« it concludes firmly: To renovate itself, this discipline has to perform its work in a new way, guided by a very precise and distinct vision on theory. The author examines the conditions for this.

  17. Cosmic questions: an introduction.

    Science.gov (United States)

    Primack, J R; Abrams, N E

    2001-12-01

    This introductory talk at the Cosmic Questions conference sponsored by the AAAS summarizes some earlier pictures of the universe and some pictures based on modern physics and cosmology. The uroboros (snake swallowing its tail) is an example of a traditional picture. The Biblical flat-earth picture was very different from the Greek spherical earth-centered picture, which was the standard view until the end of the Middle Ages. Many people incorrectly assume that the Newtonian picture of stars scattered through otherwise empty space is still the prevailing view. Seeing Earth from space shows the power of a new picture. The Hubble Space Telescope can see all the bright galaxies, all the way to the cosmic Dark Ages. We are at the center of cosmic spheres of time: looking outward is looking backward in time. All the matter and energy in the universe can be represented as a cosmic density pyramid. The laws of physics only allow the material objects in the universe to occupy a wedge-shaped region on a diagram of mass versus size. All sizes--from the smallest size scale, the Planck scale, to the entire visible universe--can be represented on the Cosmic Uroboros. There are interesting connections across this diagram, and the human scale lies in the middle.

  18. Nanodesign: some basic questions

    CERN Document Server

    Schommers, Wolfram

    2013-01-01

    There is no doubt that nanoscience will be the dominant direction for technology in this century, and that this science will influence our lives to a large extent as well as open completely new perspectives on all scientific and technological disciplines. To be able to produce optimal nanosystems with tailor-made properties, it is necessary to analyze and construct such systems in advance by adequate theoretical and computational methods. Since we work in nanoscience and nanotechnology at the ultimate level, we have to apply the basic laws of physics. What methods and tools are relevant here? The book gives an answer to this question. The background of the theoretical methods and tools is critically discussed, and also the world view on which these physical laws are based. Such a debate is not only of academic interest but is of highly general concern, and this is because we constantly move in nanoscience and nanotechnology between two extreme poles, between infinite life and total destruction . On the one ...

  19. CALCULATION AND RESEARCH OF CONTACT OPHTHALMIC DUAL APPLICATION LENSES

    Directory of Open Access Journals (Sweden)

    D. N. Cherkasova

    2015-05-01

    Full Text Available Subject of research. Algorithm for calculation of contact ophthalmic lenses for dual application has been suggested based on unified approach for their calculation. The algorithm has been tested on the composition of Goldmann ophthalmic lenses and Panfundoscope lens optical systems. Method. The condition of mutual unambiguous orientation of patient’s eye and instruments is performed at the initial calculation step by face mounting and movement of coordinate table with optical head. Then such type of patient's eye optical system model is selected that the lens would be combined with the front surface of eye cornea optical system. Pupil of patient eye is under anesthesia. At the final calculation step we determine the functions of optical lens image quality and their values based on medical and technical requirements for the components of the complex system. Main results. The algorithm for ophthalmic lenses calculation has been suggested and its correctness has been proved practically on the example of two basic models in the group of such type lenses being applied in practice as a part of complex system with ophthalmic laser coagulators. Optical calculation of Goldmann ophthalmic contact lenses and Panfundoscope is presented. The method of neutralization is optimal for Goldmann lenses. The first component in Panfundoscope operates the position of object planes whereas the second component operates the position of complex system with ophthalmocoagulator's pupils. Computer modeling of complex system "Computer model of eye-ophthalmic lens" in ZEMAX confirmed the correctness of calculation algorithm in which the criteria of diffraction image quality has been used. Application possibility of simplified computer eye model called "Reduced eye" by Verbitskiy has been demonstrated. Practical relevance. The general scientific approach to the problem of synthesis, calculation and research of complex system with contact ophthalmic lenses for diagnostics

  20. Cosmological tests with strong gravitational lenses using Gaussian processes

    Science.gov (United States)

    Yennapureddy, Manoj K.; Melia, Fulvio

    2018-03-01

    Strong gravitational lenses provide source/lens distance ratios D_{obs} useful in cosmological tests. Previously, a catalog of 69 such systems was used in a one-on-one comparison between the standard model, Λ CDM, and the Rh=ct universe, which has thus far been favored by the application of model selection tools to many other kinds of data. But in that work, the use of model parametric fits to the observations could not easily distinguish between these two cosmologies, in part due to the limited measurement precision. Here, we instead use recently developed methods based on Gaussian Processes (GP), in which D_{obs} may be reconstructed directly from the data without assuming any parametric form. This approach not only smooths out the reconstructed function representing the data, but also reduces the size of the 1σ confidence regions, thereby providing greater power to discern between different models. With the current sample size, we show that analyzing strong lenses with a GP approach can definitely improve the model comparisons, producing probability differences in the range ˜ 10-30%. These results are still marginal, however, given the relatively small sample. Nonetheless, we conclude that the probability of Rh=ct being the correct cosmology is somewhat higher than that of Λ CDM, with a degree of significance that grows with the number of sources in the subsamples we consider. Future surveys will significantly grow the catalog of strong lenses and will therefore benefit considerably from the GP method we describe here. In addition, we point out that if the Rh=ct universe is eventually shown to be the correct cosmology, the lack of free parameters in the study of strong lenses should provide a remarkably powerful tool for uncovering the mass structure in lensing galaxies.

  1. Class B0631+519: Last of the Class Lenses

    Energy Technology Data Exchange (ETDEWEB)

    York, Tom; Jackson, N.; Browne, I.W.A.; Koopmans, L.V.E.; McKean, J.P.; Norbury, M.A.; Biggs, A.D.; Blandford, R.D.; de Bruyn, A.G.; Fassnacht, C.D.; Myers, S.T.; Pearson, T.J.; Phillips, P.M.; Readhead, A.C.S.; Rusin, D.; Wilkinson, P.N.; /Jodrell Bank /Kapteyn Astron. Inst., Groningen /UC, Davis /JIVE, Dwingeloo /KIPAC, Menlo Park /NFRA,

    2005-05-31

    We report the discovery of the new gravitational lens system CLASS B0631+519. Imaging with the VLA, MERLIN and the VLBA reveals a doubly-imaged flat-spectrum radio core, a doubly-imaged steep-spectrum radio lobe and possible quadruply-imaged emission from a second lobe. The maximum separation between the lensed images is 1.16 arcsec. High resolution mapping with the VLBA at 5 GHz resolves the most magnified image of the radio core into a number of sub-components spread across approximately 20 mas. No emission from the lensing galaxy or an odd image is detected down to 0.31 mJy (5{sigma}) at 8.4 GHz. Optical and near-infrared imaging with the ACS and NICMOS cameras on the HST show that there are two galaxies along the line of sight to the lensed source, as previously discovered by optical spectroscopy. We find that the foreground galaxy at z=0.0896 is a small irregular, and that the other, at z=0.6196 is a massive elliptical which appears to contribute the majority of the lensing effect. The host galaxy of the lensed source is detected in the HST near-infrared imaging as a set of arcs, which form a nearly complete Einstein ring. Mass modeling using non-parametric techniques can reproduce the near-infrared observations and indicates that the small irregular galaxy has a (localized) effect on the flux density distribution in the Einstein ring at the 5-10% level.

  2. Bibliometric Study of Scientific Research on Scleral Lenses.

    Science.gov (United States)

    Povedano-Montero, Francisco Javier; Álvarez-Peregrina, Cristina; Hidalgo Santa Cruz, Fernando; Villa-Collar, César; Sánchez Valverde, José

    2018-01-25

    To analyze the state of scientific publications in the field of scleral lenses applying a bibliometric study. The database used in this bibliometric study was SCOPUS, the largest abstract and citation database of peer-reviewed literature: scientific journals, books, and conference proceedings. Using remote download techniques, articles published between 1962 (year of first registrations) and 2015 were selected by entering the main descriptors: "scleral contact lenses" and "scleral lenses," limiting the field for the article, keywords, and abstract, linked with the OR tab. We applied the following bibliometric indicators: Price index, doubling time and annual growth rate, Price transience index, Lotka law of scientific productivity, and Bradford zones. The authors recovered 361 contributions (articles, reviews, letters to the editor, etc.) for 1962 to 2016. The distribution for five-year periods shows a significant increase in 2012 to 2016, with a growth of 222.22% in comparison with the previous period 2012 to 2016. The countries with the highest production are the United states with 135 contributions, United Kingdom with 46, and India with 19. The most productive institutions are Harvard Medical school, Boston Foundation for Sight, and Moorfields Eye Hospital National Health Service Foundation Trust. Classification of authors based on productivity is strongly concentrated in small producers, with a transient index of 59.03. The total number of authors is 891, representing a coauthor index of 2.47 for the 361 documents retrieved. The authors with the highest productivity are Kenneth W. Pullum, Perry Rosenthal, and Deborah S. Jacobs, with an h-index between 12 and 19 documents. The number of documents published on scleral lenses shows a significant increase in the last 5 years, and currently, they represent only 1.44% of all publications on contact lenses. Bibliometric studies have become essential tools for evaluating scientific activity, allowing an overview of

  3. Gravitational lensing of gravitational waves: A statistical perspective

    Science.gov (United States)

    Li, Shun-Sheng; Mao, Shude; Zhao, Yuetong; Lu, Youjun

    2018-02-01

    In this paper we study the strong gravitational lensing of gravitational waves (GWs) from a statistical perspective, with particular focus on the high frequency GWs from stellar binary black hole coalescences. These are most promising targets for ground-based detectors such as aLIGO and the proposed Einstein Telescope (ET) and can be safely treated under the geometrical optics limit for GW propagation. We perform a thorough calculation of the lensing rate, by taking account of effects caused by the ellipticity of lensing galaxies, lens environments, and magnification bias. We find that in certain GW source rate scenarios, we should be able to observe strongly lensed GW events once per year (˜1 yr-1) in the aLIGO survey at its design sensitivity; for the proposed ET survey, the rate could be as high as ˜80 yr-1. These results depend on the estimate of GW source abundance, and hence can be correspondingly modified with an improvement in our understanding of the merger rate of stellar binary black holes. We also compute the fraction of four-image lens systems in each survey, predicting it to be ˜30 percent for the aLIGO survey and ˜6 percent for the ET survey. Finally, we evaluate the possibility of missing some images due to the finite survey duration, by presenting the probability distribution of lensing time delays. We predict that this selection bias will be insignificant in future GW surveys, as most of the lens systems (˜90%) will have time delays less than ˜1 month which will be far shorter than survey durations.

  4. Gravitational lensing of gravitational waves: a statistical perspective

    Science.gov (United States)

    Li, Shun-Sheng; Mao, Shude; Zhao, Yuetong; Lu, Youjun

    2018-05-01

    In this paper, we study the strong gravitational lensing of gravitational waves (GWs) from a statistical perspective, with particular focus on the high frequency GWs from stellar binary black hole coalescences. These are most promising targets for ground-based detectors such as Advanced Laser Interferometer Gravitational Wave Observatory (aLIGO) and the proposed Einstein Telescope (ET) and can be safely treated under the geometrical optics limit for GW propagation. We perform a thorough calculation of the lensing rate, by taking account of effects caused by the ellipticity of lensing galaxies, lens environments, and magnification bias. We find that in certain GW source rate scenarios, we should be able to observe strongly lensed GW events once per year (˜1 yr-1) in the aLIGO survey at its design sensitivity; for the proposed ET survey, the rate could be as high as ˜80 yr-1. These results depend on the estimate of GW source abundance, and hence can be correspondingly modified with an improvement in our understanding of the merger rate of stellar binary black holes. We also compute the fraction of four-image lens systems in each survey, predicting it to be ˜30 per cent for the aLIGO survey and ˜6 per cent for the ET survey. Finally, we evaluate the possibility of missing some images due to the finite survey duration, by presenting the probability distribution of lensing time delays. We predict that this selection bias will be insignificant in future GW surveys, as most of the lens systems ({˜ } 90{per cent}) will have time delays less than ˜1 month, which will be far shorter than survey durations.

  5. Predicting weak lensing statistics from halo mass reconstructions - Final Paper

    Energy Technology Data Exchange (ETDEWEB)

    Everett, Spencer [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-08-20

    As dark matter does not absorb or emit light, its distribution in the universe must be inferred through indirect effects such as the gravitational lensing of distant galaxies. While most sources are only weakly lensed, the systematic alignment of background galaxies around a foreground lens can constrain the mass of the lens which is largely in the form of dark matter. In this paper, I have implemented a framework to reconstruct all of the mass along lines of sight using a best-case dark matter halo model in which the halo mass is known. This framework is then used to make predictions of the weak lensing of 3,240 generated source galaxies through a 324 arcmin² field of the Millennium Simulation. The lensed source ellipticities are characterized by the ellipticity-ellipticity and galaxy-mass correlation functions and compared to the same statistic for the intrinsic and ray-traced ellipticities. In the ellipticity-ellipticity correlation function, I and that the framework systematically under predicts the shear power by an average factor of 2.2 and fails to capture correlation from dark matter structure at scales larger than 1 arcminute. The model predicted galaxy-mass correlation function is in agreement with the ray-traced statistic from scales 0.2 to 0.7 arcminutes, but systematically underpredicts shear power at scales larger than 0.7 arcminutes by an average factor of 1.2. Optimization of the framework code has reduced the mean CPU time per lensing prediction by 70% to 24 ± 5 ms. Physical and computational shortcomings of the framework are discussed, as well as potential improvements for upcoming work.

  6. Multipole lenses with implicit poles and with harmonic distribution of current density in a coil

    International Nuclear Information System (INIS)

    Skachkov, V.S.

    1984-01-01

    General theory of the multipole lense with implicit poles is presented. The thickness of lense coil is finite. Current density distribution in the coil cross section is harmonic in the azimuth direction and arbitrary in the radial one. The calculation of yoke contribution in the lence field is given. Two particular lense variants differing from each other in the method of current density radial distribution are considered and necessary calculated relations for the lense with and without yoke ar presented. A comparative analysis of physical and technological peculiarities of these lenses is performed

  7. Perchlorate Questions and Answers

    Science.gov (United States)

    ... 280 types of foods, including 40 types of baby food, every year from different parts of the country. ... perchlorate at the levels present in water and foods. However, you should discuss ... for a baby's normal brain development, so it is particularly important ...

  8. A question of authority

    Energy Technology Data Exchange (ETDEWEB)

    Morgan, Earl W.(BATTELLE (PACIFIC NW LAB))

    2003-10-15

    A Question of Authority. This article deals with a certain scenario and several reviewers are to give their opinion. This one is in regards to - Suspending an IACUC approved animal use activity is about the last thing a research institution wants to do. Consider the predicament that the Great Eastern University IACUC faced when Dr. Janet Jenkins, the Attending Veterinarian, suspended all animal use activity on an approved protocol of Dr. Roy Maslo. Jenkins had the IACUCs authority to temporarily suspend a protocol, subject to review by a quorum of the full committee. She alleged that Maslo used mice from his breeding colony, not purchased rats, to begin a new study. Jenkins saw Maslos technicians bringing mouse cages to a procedure room and setting up for a minor survival surgery. She asked them to wait until she clarified things as she felt confident that the protocol called for rats. She called Maslo and asked him if the study had been approved for mice, to which he responded affirmatively. Still not feeling quite assured, she went to her office, reviewed the protocol, and found only rat studies described. She also called the IACUC office to see if there were any approved amendments which she may not have received, and was told that there were none. By the time she returned, one procedure was completed. Understandably upset, she informed the technicians and Maslo that any further activity on the protocol was suspended until the issue was resolved. Jenkins informed the IACUC chairman who in turned called an emergency meeting of the committee.

  9. Questioning Questions: Elementary Teachers' Adaptations of Investigation Questions across the Inquiry Continuum

    Science.gov (United States)

    Biggers, Mandy

    2018-01-01

    Questioning is a central practice in science classrooms. However, not every question translates into a "good" science investigation. Questions that drive science investigations can be provided by many sources including the teacher, the curriculum, or the student. The variations in the source of investigation questions were explored in…

  10. Omni-focal refractive focus correction technology as a substitute for bi/multi-focal intraocular lenses, contact lenses, and spectacles

    Science.gov (United States)

    Ben Yaish, Shai; Zlotnik, Alex; Raveh, Ido; Yehezkel, Oren; Belkin, Michael; Lahav, Karen; Zalevsky, Zeev

    2009-02-01

    We present novel technology for extension in depth of focus of imaging lenses for use in ophthalmic lenses correcting myopia, hyperopia with regular/irregular astigmatism and presbyopia. This technology produces continuous focus without appreciable loss of energy. It is incorporated as a coating or engraving on the surface for spectacles, contact or intraocular lenses. It was fabricated and tested in simulations and in clinical trials. From the various testing this technology seems to provide a satisfactory single-lens solution. Obtained performance is apparently better than those of existing multi/bifocal lenses and it is modular enough to provide solution to various ophthalmic applications.

  11. A CFH12k lensing survey of X-ray luminous galaxy clusters - II. Weak lensing analysis and global correlations

    NARCIS (Netherlands)

    Bardeau, S.; Soucail, G.; Kneib, J.-P.; Czoske, O.; Ebeling, H.; Hudelot, P.; Smail, I.; Smith, G. P.

    Aims. We present a wide-field multi-color survey of a homogeneous sample of eleven clusters of galaxies for which we measure total masses and mass distributions from weak lensing. This sample, spanning a small range in both X-ray luminosity and redshift, is ideally suited to determining the

  12. The Splashback Feature around DES Galaxy Clusters: Galaxy Density and Weak Lensing Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chihway; et al.

    2017-10-18

    Splashback refers to the process of matter that is accreting onto a dark matter halo reaching its first orbital apocenter and turning around in its orbit. The cluster-centric radius at which this process occurs, r_sp, defines a halo boundary that is connected to the dynamics of the cluster, in contrast with other common halo boundary definitions such as R_200. A rapid decline in the matter density profile of the halo is expected near r_sp. We measure the galaxy number density and weak lensing mass profiles around RedMapper galaxy clusters in the first year Dark Energy Survey (DES) data. For a cluster sample with mean mass ~2.5 x 10^14 solar masses, we find strong evidence of a splashback-like steepening of the galaxy density profile and measure r_sp=1.16 +/- 0.08 Mpc/h, consistent with earlier SDSS measurements of More et al. (2016) and Baxter et al. (2017). Moreover, our weak lensing measurement demonstrates for the first time the existence of a splashback-like steepening of the matter profile of galaxy clusters. We measure r_sp=1.28 +/- 0.18 Mpc/h from the weak lensing data, in good agreement with our galaxy density measurements. Applying our analysis to different cluster and galaxy samples, we find that consistent with LambdaCDM simulations, r_sp scales with R_200m and does not evolve with redshift over the redshift range of 0.3--0.6. We also find that potential systematic effects associated with the RedMapper algorithm may impact the location of r_sp, in particular the choice of scale used to estimate cluster richness. We discuss progress needed to understand the systematic uncertainties and fully exploit forthcoming data from DES and future surveys, emphasizing the importance of more realistic mock catalogs and independent cluster samples.

  13. Algorithms and Programs for Strong Gravitational Lensing In Kerr Space-time Including Polarization

    Science.gov (United States)

    Chen, Bin; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie; Maddumage, Prasad

    2015-05-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python.

  14. ALGORITHMS AND PROGRAMS FOR STRONG GRAVITATIONAL LENSING IN KERR SPACE-TIME INCLUDING POLARIZATION

    International Nuclear Information System (INIS)

    Chen, Bin; Maddumage, Prasad; Kantowski, Ronald; Dai, Xinyu; Baron, Eddie

    2015-01-01

    Active galactic nuclei (AGNs) and quasars are important astrophysical objects to understand. Recently, microlensing observations have constrained the size of the quasar X-ray emission region to be of the order of 10 gravitational radii of the central supermassive black hole. For distances within a few gravitational radii, light paths are strongly bent by the strong gravity field of the central black hole. If the central black hole has nonzero angular momentum (spin), then a photon’s polarization plane will be rotated by the gravitational Faraday effect. The observed X-ray flux and polarization will then be influenced significantly by the strong gravity field near the source. Consequently, linear gravitational lensing theory is inadequate for such extreme circumstances. We present simple algorithms computing the strong lensing effects of Kerr black holes, including the effects on polarization. Our algorithms are realized in a program “KERTAP” in two versions: MATLAB and Python. The key ingredients of KERTAP are a graphic user interface, a backward ray-tracing algorithm, a polarization propagator dealing with gravitational Faraday rotation, and algorithms computing observables such as flux magnification and polarization angles. Our algorithms can be easily realized in other programming languages such as FORTRAN, C, and C++. The MATLAB version of KERTAP is parallelized using the MATLAB Parallel Computing Toolbox and the Distributed Computing Server. The Python code was sped up using Cython and supports full implementation of MPI using the “mpi4py” package. As an example, we investigate the inclination angle dependence of the observed polarization and the strong lensing magnification of AGN X-ray emission. We conclude that it is possible to perform complex numerical-relativity related computations using interpreted languages such as MATLAB and Python

  15. Les questions de migrations internationales

    Science.gov (United States)

    Samman, Mouna Liliane

    1993-03-01

    International migrations have growing implications for both countries of origin and countries of destination. In the latter, the presence of foreigners and of members of their families today creates problems of integration, causes argument and brings mounting xenophobia. Paralleling political, economic and social measures taken by public authorities to respond to these difficulties, education needs to assist in defusing the resulting social tensions by preparing the minds of learners and helping to develop new attitudes. In particular, when educational programmes address questions of international migration, these should be treated in the framework of historical evolution so that their real significance and their true temporal and spatial dimensions become apparent. It is also important that the growing interdependence between countries should be made plain, that national history should be placed in its international context, and that the true consequences of these developments should be made clear. In this context, learners need to be acquainted with Human Rights, thereby stressing universal moral values and the role of the individual. Lastly, questions relating to international migration are usually presented in the media in a selective and partial manner, and the young people who take in this information often accept the hasty judgments which are made of situations as proven facts. This is why all teaching about international migration needs to be considered or reconsidered in the light of the complementary or competing actions of the media.

  16. Are Quantum Theory Questions Epistemic?

    Directory of Open Access Journals (Sweden)

    Viviana Yaccuzzi Polisena

    2013-12-01

    Full Text Available How to displace-move quantum theory [Ǭ] questions-problems to philosophy? Seeing the collapse of our society’s cultural-intellectual-morals, the philosophy of the 21st century has to contribute to the formation of new principles-formalisms: the big task of the contemporary philosophy ©] is to innovate, to transform the building of the knowledge! Which is the role of the contemporary philosopher? (Noam Chomsky. Building science so that it is more human, out of the scientific mercantilism so that it does not continue transgressing that which is most precious: the thought-life. The ideas that I propose demand a deep cultural-epistemiologicscientific-philosophical-ethical rethinking that goes from quantum entities up to life in society. The starting idea is «the quantum [Ǭ], the paradigm of the contemporary science ©]» (Bernard D’Espagnat. I propose to displace-move questions of the quantum theory [Ǭ]: spin, measure, layering to the field of philosophy (φ to build generic symbols. Can the contemporary episteme model the collapse of the ? For a philosopher, can understanding the importance and the behaviour of the spin bring something new to philosophy ? Can information of the states of the spin be used to observe in a holographic way the pattern energy-information contained in the quantum entities? Is quantum [Ǭ] physics mechanical?

  17. Contact lenses purchased over the internet place individuals potentially at risk for harmful eye care practices.

    Science.gov (United States)

    Fogel, Joshua; Zidile, Chaya

    2008-01-01

    Individuals are increasingly purchasing contact lenses over the Internet. No studies exist regarding Internet purchase of contact lenses and eye care health practices. One hundred fifty-one college students were surveyed regarding contact lenses purchase category (doctor's office, store, Internet). Pearson chi-square analyses compared purchase category with responses regarding U.S. Food and Drug Administration (FDA) recommendations for purchasing contact lenses online. Analysis of variance compared contact lenses purchase category with the Time Pressure Scale (TPS). Also, correlation analyses compared the TPS with Internet eye-health statements. Contact lens purchase categories included doctor's office (43.0%), store (55.0%), and Internet (22.5%), with individuals purchasing at multiple venues. With regard to the FDA recommendations, those who purchased contact lenses at a doctor's office more often adhered to the recommendations, whereas those who purchased contact lenses at a store or the Internet did so less often. Those who purchased contact lenses over the Internet had significantly higher TPS scores. In addition, higher TPS scores were significantly correlated with various statements regarding the Internet. Those who purchase contact lenses via the Internet or store do not follow a number of FDA contact lenses recommendations. Also, those with higher TPS scores trust possible non-evidence-based contact lenses Internet information. Implications with regard to the Fairness to Contact Lens Consumers Act are discussed.

  18. Planck 2013 results. XVII. Gravitational lensing by large-scale structure

    CERN Document Server

    Ade, P.A.R.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Basak, S.; Battaner, E.; Benabed, K.; Benoit, A.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bielewicz, P.; Bobin, J.; Bock, J.J.; Bonaldi, A.; Bonavera, L.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R.C.; Cardoso, J.F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, L.Y.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; Davis, R.J.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Dechelette, T.; Delabrouille, J.; Delouis, J.M.; Desert, F.X.; Dickinson, C.; Diego, J.M.; Dole, H.; Donzelli, S.; Dore, O.; Douspis, M.; Dunkley, J.; Dupac, X.; Efstathiou, G.; Ensslin, T.A.; Eriksen, H.K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Heraud, Y.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Ho, S.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, T.R.; Jaffe, A.H.; Jones, W.C.; Juvela, M.; Keihanen, E.; Keskitalo, R.; Kisner, T.S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lagache, G.; Lahteenmaki, A.; Lamarre, J.M.; Lasenby, A.; Laureijs, R.J.; Lavabre, A.; Lawrence, C.R.; Leahy, J.P.; Leonardi, R.; Leon-Tavares, J.; Lesgourgues, J.; Lewis, A.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Maffei, B.; Maino, D.; Mandolesi, N.; Mangilli, A.; Maris, M.; Marshall, D.J.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Moss, A.; Munshi, D.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Partridge, B.; Pasian, F.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G.W.; Prezeau, G.; Prunet, S.; Puget, J.L.; Pullen, A.R.; Rachen, J.P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rubino-Martin, J.A.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M.D.; Shellard, E.P.S.; Spencer, L.D.; Starck, J.L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Umana, G.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L.A.; Wandelt, B.D.; White, M.; White, S.D.M.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-01-01

    On the arcminute angular scales probed by Planck, the CMB anisotropies are gently perturbed by gravitational lensing. Here we present a detailed study of this effect, detecting lensing independently in the 100, 143, and 217GHz frequency bands with an overall significance of greater than 25sigma. We use the temperature-gradient correlations induced by lensing to reconstruct a (noisy) map of the CMB lensing potential, which provides an integrated measure of the mass distribution back to the CMB last-scattering surface. Our lensing potential map is significantly correlated with other tracers of mass, a fact which we demonstrate using several representative tracers of large-scale structure. We estimate the power spectrum of the lensing potential, finding generally good agreement with expectations from the best-fitting LCDM model for the Planck temperature power spectrum, showing that this measurement at z=1100 correctly predicts the properties of the lower-redshift, later-time structures which source the lensing ...

  19. Business Education: Addressing the "What" Question

    Science.gov (United States)

    Almoharby, Darwish

    2008-01-01

    In an attempt to diversify the economy and stimulate private enterprise development, government agencies and private institutions in many countries have emphasized the importance of setting up and developing small and medium-size enterprises and promoting entrepreneurship. An important question confronting policy makers, however, is how they can…

  20. Seeing (and Doing) Conservation Through Cultural Lenses

    Science.gov (United States)

    Peterson, Richard B.; Russell, Diane; West, Paige; Brosius, J. Peter

    2010-01-01

    In this paper, we first discuss various vantage points gained through the authors’ experience of approaching conservation through a “cultural lens.” We then draw out more general concerns that many anthropologists hold with respect to conservation, summarizing and commenting on the work of the Conservation and Community Working Group within the Anthropology and Environment Section of the American Anthropological Association. Here we focus on both critiques and contributions the discipline of anthropology makes with regard to conservation, and show how anthropologists are moving beyond conservation critiques to engage actively with conservation practice and policy. We conclude with reflections on the possibilities for enhancing transdisciplinary dialogue and practice through reflexive questioning, the adoption of disciplinary humility, and the realization that “cross-border” collaboration among conservation scholars and practitioners can strengthen the political will necessary to stem the growing commoditization and ensuing degradation of the earth’s ecosystems.

  1. Ultraviolet or blue-filtering intraocular lenses: what is the evidence?

    Science.gov (United States)

    Downes, S M

    2016-01-01

    Cataract surgery was revolutionised by the introduction of modern intraocular lenses in the late 1940's. By the late 1960's to 1970's evidence had emerged that short-wavelength light caused phototoxicity at the retina and retinal pigment epithelium. By the early 1980's ultraviolet filters had been incorporated into intraocular lenses. This caused intense controversy, as there was concern that the UV-filtering chromophore might leach out into the eye causing toxicity. With the arrival of blue-filtering intraocular lenses (BFIOLs) in 1990's, a further debate was ignited as to their safety and potential disadvantages. Selecting the optimal performing intraocular lens to obtain the best visual performance with the fewest potential drawbacks has become complex and challenging for cataract surgeons and their patients with the wide choice of lenses available. Choosing a personalised lens to address astigmatism, presbyopia, spherical aberration, chromatic aberration, and potentially to shield the retina from short-wavelength light is now possible. The potential benefits and possible side effects of these different innovations emphasise the importance of assessing the evidence for their clinical utility, allowing the surgeon and the patient to weigh-up the risk benefit ratio and make an informed decision. The BFIOLs were developed to reduce cyanopsia, address chromatic aberration, and improve contrast sensitivity in different lighting conditions, as well as to prevent short-wavelength light reaching the retina thus potentially reducing the risk of developing age-related macular degeneration. Further design development of the BFIOLs was to mimic the natural crystalline lens absorption and transmittance properties in adulthood. Multiple publications have reported on the potential benefits and pitfalls of implanting a blue-filtering lens. The potential disadvantages raised in the literature over the last 25 years since their introduction, regarding compromise of visual

  2. Generic Drugs: Questions and Answers

    Science.gov (United States)

    ... Vaccines, Blood & Biologics Animal & Veterinary Cosmetics Tobacco Products Drugs Home Drugs Resources for You Information for Consumers (Drugs) Questions & Answers Generic Drugs: Questions & Answers Share Tweet Linkedin Pin it More ...

  3. Can we share questions? Performance of questions from different question banks in a single medical school.

    Science.gov (United States)

    Freeman, Adrian; Nicholls, Anthony; Ricketts, Chris; Coombes, Lee

    2010-01-01

    To use progress testing, a large bank of questions is required, particularly when planning to deliver tests over a long period of time. The questions need not only to be of good quality but also balanced in subject coverage across the curriculum to allow appropriate sampling. Hence as well as creating its own questions, an institution could share questions. Both methods allow ownership and structuring of the test appropriate to the educational requirements of the institution. Peninsula Medical School (PMS) has developed a mechanism to validate questions written in house. That mechanism can be adapted to utilise questions from an International question bank International Digital Electronic Access Library (IDEAL) and another UK-based question bank Universities Medical Assessment Partnership (UMAP). These questions have been used in our progress tests and analysed for relative performance. Data are presented to show that questions from differing sources can have comparable performance in a progress testing format. There are difficulties in transferring questions from one institution to another. These include problems of curricula and cultural differences. Whilst many of these difficulties exist, our experience suggests that it only requires a relatively small amount of work to adapt questions from external question banks for effective use. The longitudinal aspect of progress testing (albeit summatively) may allow more flexibility in question usage than single high stakes exams.

  4. Robustness Analysis of Visual Question Answering Models by Basic Questions

    KAUST Repository

    Huang, Jia-Hong

    2017-11-01

    Visual Question Answering (VQA) models should have both high robustness and accuracy. Unfortunately, most of the current VQA research only focuses on accuracy because there is a lack of proper methods to measure the robustness of VQA models. There are two main modules in our algorithm. Given a natural language question about an image, the first module takes the question as input and then outputs the ranked basic questions, with similarity scores, of the main given question. The second module takes the main question, image and these basic questions as input and then outputs the text-based answer of the main question about the given image. We claim that a robust VQA model is one, whose performance is not changed much when related basic questions as also made available to it as input. We formulate the basic questions generation problem as a LASSO optimization, and also propose a large scale Basic Question Dataset (BQD) and Rscore (novel robustness measure), for analyzing the robustness of VQA models. We hope our BQD will be used as a benchmark for to evaluate the robustness of VQA models, so as to help the community build more robust and accurate VQA models.

  5. Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances.

    Science.gov (United States)

    Leung, Tsz Wing; Li, Roger Wing-Hong; Kee, Chea-Su

    2017-01-01

    To evaluate the optical performance of blue-light filtering spectacle lenses and investigate whether a reduction in blue light transmission affects visual performance and sleep quality. Experiment 1: The relative changes in phototoxicity, scotopic sensitivity, and melatonin suppression of five blue-light filtering plano spectacle lenses were calculated based on their spectral transmittances measured by a spectrophotometer. Experiment 2: A pseudo-randomized controlled study was conducted to evaluate the clinical performance of two blue-light filtering spectacle lenses (BF: blue-filtering anti-reflection coating; BT: brown-tinted) with a regular clear lens (AR) serving as a control. A total of eighty computer users were recruited from two age cohorts (young adults: 18-30 yrs, middle-aged adults: 40-55 yrs). Contrast sensitivity under standard and glare conditions, and colour discrimination were measured using standard clinical tests. After one month of lens wear, subjective ratings of lens performance were collected by questionnaire. All tested blue-light filtering spectacle lenses theoretically reduced the calculated phototoxicity by 10.6% to 23.6%. Although use of the blue-light filters also decreased scotopic sensitivity by 2.4% to 9.6%, and melatonin suppression by 5.8% to 15.0%, over 70% of the participants could not detect these optical changes. Our clinical tests revealed no significant decrease in contrast sensitivity either with (95% confidence intervals [CI]: AR-BT [-0.05, 0.05]; AR-BF [-0.05, 0.06]; BT-BF [-0.06, 0.06]) or without glare (95% CI: AR-BT [-0.01, 0.03]; AR-BF [-0.01, 0.03]; BT-BF [-0.02, 0.02]) and colour discrimination (95% CI: AR-BT [-9.07, 1.02]; AR-BF [-7.06, 4.46]; BT-BF [-3.12, 8.57]). Blue-light filtering spectacle lenses can partially filter high-energy short-wavelength light without substantially degrading visual performance and sleep quality. These lenses may serve as a supplementary option for protecting the retina from potential

  6. Blue-Light Filtering Spectacle Lenses: Optical and Clinical Performances

    Science.gov (United States)

    2017-01-01

    Purposes To evaluate the optical performance of blue-light filtering spectacle lenses and investigate whether a reduction in blue light transmission affects visual performance and sleep quality. Methods Experiment 1: The relative changes in phototoxicity, scotopic sensitivity, and melatonin suppression of five blue-light filtering plano spectacle lenses were calculated based on their spectral transmittances measured by a spectrophotometer. Experiment 2: A pseudo-randomized controlled study was conducted to evaluate the clinical performance of two blue-light filtering spectacle lenses (BF: blue-filtering anti-reflection coating; BT: brown-tinted) with a regular clear lens (AR) serving as a control. A total of eighty computer users were recruited from two age cohorts (young adults: 18–30 yrs, middle-aged adults: 40–55 yrs). Contrast sensitivity under standard and glare conditions, and colour discrimination were measured using standard clinical tests. After one month of lens wear, subjective ratings of lens performance were collected by questionnaire. Results All tested blue-light filtering spectacle lenses theoretically reduced the calculated phototoxicity by 10.6% to 23.6%. Although use of the blue-light filters also decreased scotopic sensitivity by 2.4% to 9.6%, and melatonin suppression by 5.8% to 15.0%, over 70% of the participants could not detect these optical changes. Our clinical tests revealed no significant decrease in contrast sensitivity either with (95% confidence intervals [CI]: AR–BT [–0.05, 0.05]; AR–BF [–0.05, 0.06]; BT–BF [–0.06, 0.06]) or without glare (95% CI: AR–BT [–0.01, 0.03]; AR–BF [–0.01, 0.03]; BT–BF [–0.02, 0.02]) and colour discrimination (95% CI: AR–BT [–9.07, 1.02]; AR–BF [–7.06, 4.46]; BT–BF [–3.12, 8.57]). Conclusion Blue-light filtering spectacle lenses can partially filter high-energy short-wavelength light without substantially degrading visual performance and sleep quality. These lenses may

  7. Questioning as a teaching tool.

    Science.gov (United States)

    Long, Michele; Blankenburg, Rebecca; Butani, Lavjay

    2015-03-01

    The Dreyfus and Bloom frameworks can help the great clinical teacher craft questions that are learner-centric and appropriately challenging.Employing strategies to ask the right questions in the right way can further add to the effectiveness of using questions as a valuable teaching,learning, and assessment tool.

  8. [Genetic questions of hemophilia].

    Science.gov (United States)

    Weissbach, G; Lenk, H

    1981-06-01

    importance, for the search of female conductors the whole lineage must be worked up genealogically, at least over four generations and with the help of archives material. The genetic consultation of haemophils and female conductors should be performed early and directedly, for important reasons also repeatedly.

  9. The DES Science Verification Weak Lensing Shear Catalogs

    International Nuclear Information System (INIS)

    Jarvis, M.

    2016-01-01

    We present weak lensing shear catalogs for 139 square degrees of data taken during the Science Verification (SV) time for the new Dark Energy Camera (DECam) being used for the Dark Energy Survey (DES). We describe our object selection, point spread function estimation and shear measurement procedures using two independent shear pipelines, IM3SHAPE and NGMIX, which produce catalogs of 2.12 million and 3.44 million galaxies respectively. We also detail a set of null tests for the shear measurements and find that they pass the requirements for systematic errors at the level necessary for weak lensing science applications using the SV data. Furthermore, we discuss some of the planned algorithmic improvements that will be necessary to produce sufficiently accurate shear catalogs for the full 5-year DES, which is expected to cover 5000 square degrees

  10. Thermal lensing compensation for AIGO high optical power test facility

    International Nuclear Information System (INIS)

    Degallaix, Jerome; Zhao Chunnong; Ju Li; Blair, David

    2004-01-01

    We present finite element modelling of thermal lensing occurring in an interferometer test mass. Our simulations include the thermo-optic effect and mechanical expansion of the optics. For the High Optical Power Test Facility (HOPTF) operated by the Australian International Gravitational Observatory (AIGO), the optical path length measured across the laser beam radius is 45 nm for 1.2 W absorbed power for the input sapphire test mass. The AIGO thermal lens is much stronger than the one in Advanced LIGO and will degrade the interferometer performance. Direct thermal compensation and the use of an external compensation plate were investigated to minimize thermal lensing consequences in the interferometer. For the AIGO situation, a fused silica external plate is the most practical solution to correct thermally induced wavefront distortions. The compensation plate requires lower thermal power than direct compensation and does not increase the test mass temperature

  11. Users' and nonusers' evaluations of the CPF 550 lenses.

    Science.gov (United States)

    Morrissette, D L; Mehr, E B; Keswick, C W; Lee, P N

    1984-11-01

    Thirty-six subjects completed questionnaires on their experiences wearing the CPF 550 lenses. Twenty-six subjects [21 with retinitis pigmentosa (RP)] were users of the 550's and 10 subjects (6 with RP) were nonusers who had rejected the 550's after a trial period. Subjects were asked about such factors as effects on adaptation time, ocular comfort, visual functioning, acceptability of tint strength in various lighting conditions, cosmetic appearance, effects of weather, and replacement intent. Users reported reduced adaptation time in changes of illumination, increased ocular comfort, improved visual functioning with the exception of poor color discrimination, and cosmetic acceptability. Satisfaction with tint strength varied with degree of illumination; usefulness in different types of weather also varied depending on the condition. Nonusers' responses were mixed; they were less likely to report improvements with the CPF 550 lenses compared to the users' group.

  12. Weak gravitational lensing towards high-precision cosmology

    International Nuclear Information System (INIS)

    Berge, Joel

    2007-01-01

    This thesis aims at studying weak gravitational lensing as a tool for high-precision cosmology. We first present the development and validation of a precise and accurate tool for measuring gravitational shear, based on the shapelets formalism. We then use shapelets on real images for the first time, we analyze CFHTLS images, and combine them with XMM-LSS data. We measure the normalisation of the density fluctuations power spectrum σ 8 , and the one of the mass-temperature relation for galaxy clusters. The analysis of the Hubble space telescope COSMOS field confirms our σ 8 measurement and introduces tomography. Finally, aiming at optimizing future surveys, we compare the individual and combined merits of cluster counts and power spectrum tomography. Our results demonstrate that next generation surveys will allow weak lensing to yield its full potential in the high-precision cosmology era. (author) [fr

  13. Precision cosmology from future lensed gravitational wave and electromagnetic signals.

    Science.gov (United States)

    Liao, Kai; Fan, Xi-Long; Ding, Xuheng; Biesiada, Marek; Zhu, Zong-Hong

    2017-10-27

    The standard siren approach of gravitational wave cosmology appeals to the direct luminosity distance estimation through the waveform signals from inspiralling double compact binaries, especially those with electromagnetic counterparts providing redshifts. It is limited by the calibration uncertainties in strain amplitude and relies on the fine details of the waveform. The Einstein telescope is expected to produce 10 4 -10 5 gravitational wave detections per year, 50-100 of which will be lensed. Here, we report a waveform-independent strategy to achieve precise cosmography by combining the accurately measured time delays from strongly lensed gravitational wave signals with the images and redshifts observed in the electromagnetic domain. We demonstrate that just 10 such systems can provide a Hubble constant uncertainty of 0.68% for a flat lambda cold dark matter universe in the era of third-generation ground-based detectors.

  14. Gravitational Lensing as a Probe of Cold Dark Matter Subhalos

    Directory of Open Access Journals (Sweden)

    Erik Zackrisson

    2010-01-01

    Full Text Available In the cold dark matter scenario, dark matter halos are assembled hierarchically from smaller subunits. Some of these subunits are disrupted during the merging process, whereas others survive temporarily in the form of subhalos. A long-standing problem with this picture is that the number of subhalos predicted by simulations exceeds the number of luminous dwarf galaxies seen in the vicinity of large galaxies like the Milky Way. Many of the subhalos must therefore have remained dark or very faint. If cold dark matter subhalos are as common as predicted, gravitational lensing may in principle offer a promising route to detection. In this paper, we describe the many ways through which lensing by subhalos can manifest itself, and summarize the results from current efforts to constrain the properties of cold dark matter subhalos using such effects.

  15. Experimental studies of stable confined electron clouds using Gabor lenses

    CERN Document Server

    Meusel, O.; Glaeser, B.; Schulte, K.

    2013-04-22

    Based on the idea of D. Gabor [1] space charge lenses are under investigation to be a powerful focussing device for intense ion beams. A stable confined electron column is used to provide strong radially symmetric electrostatic focussing, e.g. for positively charged ion beams. The advantages of Gabor lenses are a mass independent focussing strength, space charge compensation of the ion beam and reduced magnetic or electric fields compared to conventional focussing devices. Collective phenomena of the electron cloud result in aberrations and emittance growth of the ion beam. The knowledge of the behaviour of the electron cloud prevents a decrease of the beam brilliance. Numerical models developed to describe the electron confinement and dynamics within a Gabor lens help to understand the interaction of the ion beam with the electron column and show the causes of non-neutral plasma instabilities. The diagnosis of the electron cloud properties helps to evaluate the numerical models and to investigate the influen...

  16. Children's questions: a mechanism for cognitive development.

    Science.gov (United States)

    Chouinard, Michael M

    2007-01-01

    Preschoolers' questions may play an important role in cognitive development. When children encounter a problem with their current knowledge state (a gap in their knowledge, some ambiguity they do not know how to resolve, some inconsistency they have detected), asking a question allows them to get targeted information exactly when they need it. This information is available to them when they are particularly receptive to it, and because it comes as the result of their own disequilibrium, it may have depth of processing benefits. In that questions allow children to get information they need to move their knowledge structures closer to adult-like states, the ability to ask questions to gather needed information constitutes an efficient mechanism for cognitive development (referred to in this paper as the Information Requesting Mechanism [IRM]; this term is used because it includes question-asking and other information recruiting behaviors such as gestures, expressions, and vocalizations). However, the role of children's questions in their cognitive development has been largely overlooked. If questions are a force in cognitive development, the following must be true: (1) children must actually ask questions that gather information; (2) children must receive informative answers to their questions if they are able to be of use to cognitive development; (3) children must be motivated to get the information they request, rather than asking questions for other purposes such as attention; (4) the questions children ask must be relevant and of potential use to their cognitive development; (5) we must see evidence that children's questions help them in some way-that is, that they can ask questions for a purpose, and use the information they receive purposefully to successfully achieve some change of knowledge state. This monograph reports data on these points. Study 1 analyzed questions taken from four children's transcripts in the CHILDES database (age 1;2-5;1). This

  17. Evaluation of antioxidants and argpyrimidine in normal and cataractous lenses in north Indian population

    Directory of Open Access Journals (Sweden)

    Bharani K Mynampati

    2017-07-01

    Full Text Available AIM: To assess the level of glutathione, thioltransferase, and argpyrimidine in nuclear and cortical cataractous lenses as well as in the clear lenses in the north Indian population. METHODS: Human cataractous lenses were collected from the patients who underwent extracapsular cataract extraction surgery; clear lenses were collected from the freshly donated eye bank eyes. Antioxidant molecules such as glutathione and thioltransferase enzyme activity were measured; simultaneously in these lenses a blue fluorophore argpyrimidine, an advanced glycation end (AGE product level was assessed using high performance liquid chromatography (HPLC. RESULTS: The protein concentration was found to be present at higher levels in the control lenses compared to cataract lenses. A significant decrease in the glutathione level was observed in the nuclear cataractous lenses compared to cortical cataractous (P=0.004 and clear lenses (P≤0.005, but no significant change in the level of antioxidant enzyme thioltransferase was observed. Further, argpyrimidine a blue fluorophore (AGE was found to be significantly higher in the nuclear cataract (P=0.013 compared to cortical cataract lenses. CONCLUSION: Antioxidants such as glutathione significantly decrease in age-related nuclear and cortical cataract and an AGE, argpyrimidine are present at significantly higher levels in nuclear cataract.

  18. Therapeutic use of mini-scleral lenses in a patient with Graves' ophthalmopathy.

    Science.gov (United States)

    Harthan, Jennifer S

    2014-01-01

    Patients with Graves' ophthalmopathy can be very challenging to manage secondary to the complex nature of their disease presentation. Patients may present with a variety of ocular findings including: lid retraction, periorbital and lid swelling, chemosis, conjunctival hyperemia, proptosis, optic neuropathy, restrictive myopathy, exposure keratopathy and/or keratoconjunctivitis sicca. Mini-scleral and scleral lens designs have been important in the management of irregular and regular corneas, and in the therapy of ocular surface diseases. We present here the case of a 48-year-old Caucasian male who had been diagnosed with Graves' ophthalmopathy 13 years earlier. With significant ocular surface staining and over ten diopters of astigmatism, the patient had never been able to wear contact lenses comfortably. After being fit with the Mini-Scleral Design™ lenses, his vision improved to 20/25 OU, his ocular surface improved, and overall quality of vision increased. Copyright © 2012 Spanish General Council of Optometry. Published by Elsevier Espana. All rights reserved.

  19. A gravitationally lensed starburst galaxy at z=1.03 detected by SOFIA/HAWC+

    Science.gov (United States)

    Brown, Arianna; Ma, Jingzhe; Cooray, Asantha; Nayyeri, Hooshang; Timmons, Nicholas

    2018-01-01

    We present a high S/N~20 detection at 89 micron (in 15 mins) of the Herschel-selected gravitationally lensed starburst galaxy HATLASJ1429-0028 with the High-resolution Airborne Wideband Camera-plus (HAWC+) onboard the Stratospheric Observatory for Infrared Astronomy (SOFIA). The spectacular lensing system consists of an edge-on foreground disk galaxy at z=0.22 and a nearly complete Einstein ring of an intrinsic ultra-luminous infrared galaxy at z=1.03. Is this high luminosity powered by pure star formation (SF) or an active galactic nucleus (AGN)? Previous nebular line diagnostics indicate that it is star-formation dominated. SOFIA/HAWC+ allows the broad-band spectral energy distribution of the galaxy to be studied between 20 - 100 micron, which is an important wavelength range for further constraining the fractional AGN contribution to the total IR luminosity. Multi-wavelength SED modeling constrains the AGN fraction to be SOFIA/HAWC+ for distant galaxy studies and the potential to decompose SF/AGN that cannot be obtained with other current facilities.

  20. NASA Fluid Lensing & MiDAR - Next-Generation Remote Sensing Technologies for Aquatic Remote Sensing

    Science.gov (United States)

    Chirayath, Ved

    2018-01-01

    Piti's Tepungan Bay and Tumon Bay, two of five marine preserves in Guam, have not been mapped to a level of detail sufficient to support proposed management strategies. This project addresses this gap by providing high resolution maps to promote sustainable, responsible use of the area while protecting natural resources. Dr. Chirayath, a research scientist at the NASA Ames Laboratory, developed a theoretical model and algorithm called 'Fluid Lensing'. Fluid lensing removes optical distortions caused by moving water, improving the clarity of the images taken of the corals below the surface. We will also be using MiDAR, a next-generation remote sensing instrument that provides real-time multispectral video using an array of LED emitters coupled with NASA's FluidCam Imaging System, which may assist Guam's coral reef response team in understanding the severity and magnitude of coral bleaching events. This project will produce a 3D orthorectified model of the shallow water coral reef ecosystems in Tumon Bay and Piti marine preserves. These 3D models may be printed, creating a tactile diorama and increasing understanding of coral reefs among various audiences, including key decision makers. More importantly, the final data products can enable accurate and quantitative health assessment capabilities for coral reef ecosystems.

  1. Singular lensing from the scattering on special space-time defects

    Science.gov (United States)

    Mavromatos, Nick E.; Papavassiliou, Joannis

    2018-01-01

    It is well known that certain special classes of self-gravitating point-like defects, such as global (non gauged) monopoles, give rise to non-asymptotically flat space-times characterized by solid angle deficits, whose size depends on the details of the underlying microscopic models. The scattering of electrically neutral particles on such space-times is described by amplitudes that exhibit resonant behaviour when thescattering and deficit angles coincide. This, in turn, leads to ring-like structures where the cross sections are formally divergent ("singular lensing"). In this work, we revisit this particular phenomenon, with the twofold purpose of placing it in a contemporary and more general context, in view of renewed interest in the theory and general phenomenology of such defects, and, more importantly, of addressing certain subtleties that appear in the particular computation that leads to the aforementioned effect. In particular, by adopting a specific regularization procedure for the formally infinite Legendre series encountered, we manage to ensure the recovery of the Minkowski space-time, and thus the disappearance of the lensing phenomenon, in the no-defect limit, and the validity of the optical theorem for the elastic total cross section. In addition, the singular nature of the phenomenon is confirmed by means of an alternative calculation, which, unlike the original approach, makes no use of the generating function of the Legendre polynomials, but rather exploits the asymptotic properties of the Fresnel integrals.

  2. Comparative Evaluation of Ultraviolet and Visible Light Transmittance through Prescriptive Ophthalmic Minus Lenses

    Directory of Open Access Journals (Sweden)

    Mohammadreza Nazari

    2014-06-01

    Full Text Available Background: Wearing spectacles is the most common approach in correcting the refractive errors worldwide. Due to harmful effects of overexposure to solar ultraviolet radiations, the usage of multi-layer coatings in ophthalmic lenses has recently been increased. These lenses can reduce the reflections and hence increase the transmission of visible light; they can also decrease the transmission of ultraviolet rays. This study aims to compare the transmission of ultraviolet (A and B and visible rays through coated and uncoated prescriptive ophthalmic plastic lenses.Materials and Methods: In this study, 39 minus non-photochromic multi-coated white plastic single-vision lenses; 9 similar lenses but without any coatings were assessed by spectral transmittancemeter for evaluation of the transmission of visible and ultraviolet rays.Results: The transmission of visible light was 97.9%±1.07% for coated lenses and 93.5%±0.54% for lenses without coating. Ultraviolet-A transmission was 12.15%±8.02% for coated lenses compared to 66.27%±23.92% in lenses without coating. The transmission of ultraviolet-B rays was 1.21%±0.4% and 23.0%±15.97% for lenses with and without coatings, respectively.Conclusion: The transmission of visible light was significantly higher in multi-coated lenses compared to uncoated samples; whereas the transmissions of ultraviolet rays in multi-coated lenses were significantly lower than uncoated ones. Therefore, it is recommended that, except for particular cases, prescribed lenses be equipped with this multi-layer coating.

  3. CMB Beam Systematics: Impact on Lensing Parameter Estimation

    OpenAIRE

    Miller, N. J.; Shimon, M.; Keating, B. G.

    2008-01-01

    The CMB's B-mode polarization provides a handle on several cosmological parameters most notably the tensor-to-scalar ratio, $r$, and is sensitive to parameters which govern the growth of large scale structure (LSS) and evolution of the gravitational potential. The primordial gravitational-wave- and secondary lensing-induced B-mode signals are very weak and therefore prone to various foregrounds and systematics. In this work we use Fisher-matrix-based estimations and apply, for the first time,...

  4. Some aspects of powerful lasers and aspheric lenses design

    International Nuclear Information System (INIS)

    Metz, Jean de

    1976-01-01

    Gigawatt power glass lasers are described. Geometrical, interferometric, coherence and focusing aspects of the beam are measured. Design of disc amplifier is shown with high gain glass. Aspheric lenses are designed and tested for focussing these beams. Experiments of multi-breakdown in gas are done. We get fusion in plasma made by second harmonic frequency of our 1.06 μ beam. Effect of self-focussing on laser beam quality is studied. (author) [fr

  5. Strategies to regulate myopia progression with contact lenses: a review

    OpenAIRE

    González-Méijome, José Manuel; Matos, Sofia Cláudia Peixoto; Ribeiro, Miguel António Faria; Ferreira, Daniela Patrícia Lopes; Jorge, Jorge; Legerton, Jerry; Queirós, A.

    2016-01-01

    Purpose: Higher myopic refractive errors are associated with serious ocular complications that can put visual function at risk. There is respective interest in slowing and if possible stopping myopia progression before it reaches a level associated with increased risk of secondary pathology. The purpose of this report was to review our understanding of the rationale(s) and success of contact lenses (CLs) used to reduce myopia progression. Methods: A review commenced by searc...

  6. 3D weak lensing with spin wavelets on the ball

    Science.gov (United States)

    Leistedt, Boris; McEwen, Jason D.; Kitching, Thomas D.; Peiris, Hiranya V.

    2015-12-01

    We construct the spin flaglet transform, a wavelet transform to analyze spin signals in three dimensions. Spin flaglets can probe signal content localized simultaneously in space and frequency and, moreover, are separable so that their angular and radial properties can be controlled independently. They are particularly suited to analyzing cosmological observations such as the weak gravitational lensing of galaxies. Such observations have a unique 3D geometrical setting since they are natively made on the sky, have spin angular symmetries, and are extended in the radial direction by additional distance or redshift information. Flaglets are constructed in the harmonic space defined by the Fourier-Laguerre transform, previously defined for scalar functions and extended here to signals with spin symmetries. Thanks to various sampling theorems, both the Fourier-Laguerre and flaglet transforms are theoretically exact when applied to bandlimited signals. In other words, in numerical computations the only loss of information is due to the finite representation of floating point numbers. We develop a 3D framework relating the weak lensing power spectrum to covariances of flaglet coefficients. We suggest that the resulting novel flaglet weak lensing estimator offers a powerful alternative to common 2D and 3D approaches to accurately capture cosmological information. While standard weak lensing analyses focus on either real- or harmonic-space representations (i.e., correlation functions or Fourier-Bessel power spectra, respectively), a wavelet approach inherits the advantages of both techniques, where both complicated sky coverage and uncertainties associated with the physical modeling of small scales can be handled effectively. Our codes to compute the Fourier-Laguerre and flaglet transforms are made publicly available.

  7. Moment aberrations in magneto-electrostatic plasma lenses (computer simulation)

    CERN Document Server

    Butenko, V I

    2001-01-01

    In this work moment aberrations in the plasma magneto-electrostatic lenses are considered in more detail with the use of the computer modeling. For solution of the problem we have developed a special computer code - the model of plasma optical focusing device, allowing to display the main parameters and operations of experimental sample of a lens, to simulate the moment and geometrical aberrations and give recommendations on their elimination.

  8. Weak gravitational lensing systematic errors in the dark energy survey

    Science.gov (United States)

    Plazas, Andres Alejandro

    Dark energy is one of the most important unsolved problems in modern Physics, and weak gravitational lensing (WL) by mass structures along the line of sight ("cosmic shear") is a promising technique to learn more about its nature. However, WL is subject to numerous systematic errors which induce biases in measured cosmological parameters and prevent the development of its full potential. In this thesis, we advance the understanding of WL systematics in the context of the Dark Energy Survey (DES). We develop a testing suite to assess the performance of the shapelet-based DES WL measurement pipeline. We determine that the measurement bias of the parameters of our Point Spread Function (PSF) model scales as (S/N )-2, implying that a PSF S/N > 75 is needed to satisfy DES requirements. PSF anisotropy suppression also satisfies the requirements for source galaxies with S/N ≳ 45. For low-noise, marginally-resolved exponential galaxies, the shear calibration errors are up to about 0.06% (for shear values ≲ 0.075). Galaxies with S/N ≳ 75 present about 1% errors, sufficient for first-year DES data. However, more work is needed to satisfy full-area DES requirements, especially in the high-noise regime. We then implement tests to validate the high accuracy of the map between pixel coordinates and sky coordinates (astrometric solution), which is crucial to detect the required number of galaxies for WL in stacked images. We also study the effect of atmospheric dispersion on cosmic shear experiments such as DES and the Large Synoptic Survey Telescope (LSST) in the four griz bands. For DES (LSST), we find systematics in the g and r (g, r, and i) bands that are larger than required. We find that a simple linear correction in galaxy color is accurate enough to reduce dispersion shear systematics to insignificant levels in the r ( i) band for DES (LSST). More complex corrections will likely reduce the systematic cosmic-shear errors below statistical errors for LSST r band

  9. Can multiple-choice questions simulate free-response questions?

    OpenAIRE

    Lin, Shih-Yin; Singh, Chandralekha

    2016-01-01

    We discuss a study to evaluate the extent to which free-response questions could be approximated by multiple-choice equivalents. Two carefully designed research-based multiple-choice questions were transformed into a free-response format and administered on the final exam in a calculus-based introductory physics course. The original multiple-choice questions were administered in another similar introductory physics course on final exam. Findings suggest that carefully designed multiple-choice...

  10. Combining Galaxy-Galaxy Lensing and Galaxy Clustering

    Energy Technology Data Exchange (ETDEWEB)

    Park, Youngsoo [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Krause, Elisabeth [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Dodelson, Scott [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Jain, Bhuvnesh [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Amara, Adam [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Becker, Matt [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Bridle, Sarah [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Clampitt, Joseph [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Crocce, Martin [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Honscheid, Klaus [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Gaztanaga, Enrique [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Sanchez, Carles [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Wechsler, Risa [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States)

    2015-01-01

    Combining galaxy-galaxy lensing and galaxy clustering is a promising method for inferring the growth rate of large scale structure, a quantity that will shed light on the mechanism driving the acceleration of the Universe. The Dark Energy Survey (DES) is a prime candidate for such an analysis, with its measurements of both the distribution of galaxies on the sky and the tangential shears of background galaxies induced by these foreground lenses. By constructing an end-to-end analysis that combines large-scale galaxy clustering and small-scale galaxy-galaxy lensing, we also forecast the potential of a combined probes analysis on DES datasets. In particular, we develop a practical approach to a DES combined probes analysis by jointly modeling the assumptions and systematics affecting the different components of the data vector, employing a shared halo model, HOD parametrization, photometric redshift errors, and shear measurement errors. Furthermore, we study the effect of external priors on different subsets of these parameters. We conclude that DES data will provide powerful constraints on the evolution of structure growth in the universe, conservatively/ optimistically constraining the growth function to 8%/4.9% with its first-year data covering 1000 square degrees, and to 4%/2.3% with its full five-year data covering 5000 square degrees.

  11. FISHEYE LENSES FOR 3D MODELING: EVALUATIONS AND CONSIDERATIONS

    Directory of Open Access Journals (Sweden)

    L. Barazzetti

    2017-02-01

    Full Text Available Fisheye lenses are becoming more popular in complete image-based modelling projects of small and narrow spaces. The growing interest in fisheye lenses is confirmed by the availability of different commercial software incorporating a fisheye camera model. Such software are now able to carry out the steps of the image processing pipeline in a fully automated way, from camera calibration and orientation to dense matching, surface generation, and orthophoto production. This paper highlights the advantages (and disadvantages of fisheye lenses when used for 3D modelling projects through different commercial software. The goal is not only a comparison of commercial software, but also an analysis of the additional issues that arise when a fisheye lens is used for 3D modelling. Results confirm that a fisheye lens is suitable for accurate metric documentation, especially when limited space is available. On the other hand, additional issues where found during the camera calibration/image orientation step as well as the texture generation and orthophoto production phases, for which particular attention is required.

  12. Electrically controllable ionic polymeric gels as adaptive optical lenses

    Science.gov (United States)

    Salehpoor, Karim; Shahinpoor, Mohsen; Mojarrad, Mehran

    1996-02-01

    Reversible change in optical properties of ionic polymeric gels, 2-acrylamido-2-methylpropane sulfonic acid (PAMPS) and polyacrylic acid plus sodium acrylate cross-linked with bisacrylamide (PAAM), under the effect of an electric field is reported. The shape of a cylindrical piece of the gel, with flat top and bottom surfaces, changed when affected by an electric field. The top surface became curved and the sense of the curvature (whether concave or convex) depended on the polarity of the applied electric field. The curvature of the surface changed from concave to convex and vice versa by changing the polarity of the electric field. By the use of an optical apparatus, focusing capability of the curved surface was verified and the focal length of the deformed gel was measured. The effect of the intensity of the applied electric field on the surface curvature and thus, on the focal length of the gel are tested. Different mechanisms are discussed; either of them or their combination may explain the surface deformation and curvature. Practical difficulties in the test procedure and the future potential of the electrically adaptive and active optical lenses are also discussed. These adaptive lenses may be considered as smart adaptive lenses for contact lens or other optical applications requiring focal point undulation.

  13. Acanthamoeba keratitis in patients wearing scleral contact lenses.

    Science.gov (United States)

    Sticca, Matheus Porto; Carrijo-Carvalho, Linda C; Silva, Isa M B; Vieira, Luiz A; Souza, Luciene B; Junior, Rubens Belfort; Carvalho, Fábio Ramos S; Freitas, Denise

    2017-12-05

    To report a series of cases of Acanthamoeba keratitis (AK) in scleral lens wearers with keratoconus to determine whether this type of contact lens presents a greater risk for development of infection. This study reports three patients who wore scleral contact lenses to correct keratoconus and developed AK. The diagnoses of AK were established based on cultures of the cornea, scleral contact lenses, and contact lens paraphernalia. This study investigated the risk factors for infections. The possible risks for AK in scleral contact lens wearers are hypoxic changes in the corneal epithelium because of the large diameter and minimal tear exchange, use of large amounts of saline solution necessary for scleral lens fitting, storing the scleral lens overnight in saline solution rather than contact lens multipurpose solutions, not rubbing the contact lens during cleaning, and the space between the cornea and the back surface of the scleral lens that might serve as a fluid reservoir and environment for Acanthamoeba multiplication. Two patients responded well to medical treatment of AK; one is still being treated. The recommendations for use and care of scleral contact lenses should be emphasized, especially regarding use of sterile saline (preferably single use), attention to rubbing the lens during cleaning, cleaning of the plunger, and overnight storage in fresh contact lens multipurpose solutions without topping off the lens solution in the case. Copyright © 2017. Published by Elsevier Ltd.

  14. THE THIRD GRAVITATIONAL LENSING ACCURACY TESTING (GREAT3) CHALLENGE HANDBOOK

    International Nuclear Information System (INIS)

    Mandelbaum, Rachel; Kannawadi, Arun; Simet, Melanie; Rowe, Barnaby; Kacprzak, Tomasz; Bosch, James; Miyatake, Hironao; Chang, Chihway; Gill, Mandeep; Courbin, Frederic; Jarvis, Mike; Armstrong, Bob; Lackner, Claire; Leauthaud, Alexie; Nakajima, Reiko; Rhodes, Jason; Zuntz, Joe; Bridle, Sarah; Coupon, Jean; Dietrich, Jörg P.

    2014-01-01

    The GRavitational lEnsing Accuracy Testing 3 (GREAT3) challenge is the third in a series of image analysis challenges, with a goal of testing and facilitating the development of methods for analyzing astronomical images that will be used to measure weak gravitational lensing. This measurement requires extremely precise estimation of very small galaxy shape distortions, in the presence of far larger intrinsic galaxy shapes and distortions due to the blurring kernel caused by the atmosphere, telescope optics, and instrumental effects. The GREAT3 challenge is posed to the astronomy, machine learning, and statistics communities, and includes tests of three specific effects that are of immediate relevance to upcoming weak lensing surveys, two of which have never been tested in a community challenge before. These effects include many novel aspects including realistically complex galaxy models based on high-resolution imaging from space; a spatially varying, physically motivated blurring kernel; and a combination of multiple different exposures. To facilitate entry by people new to the field, and for use as a diagnostic tool, the simulation software for the challenge is publicly available, though the exact parameters used for the challenge are blinded. Sample scripts to analyze the challenge data using existing methods will also be provided. See http://great3challenge.info and http://great3.projects.phys.ucl.ac.uk/leaderboard/ for more information

  15. An experimental study of nanoparticle focusing with aerodynamic lenses

    Science.gov (United States)

    Wang, Xiaoliang; McMurry, Peter H.

    2006-12-01

    High sampling efficiencies of analyte ions, molecules or particles are needed to maximize the sensitivity of mass spectrometers. "Ion funnels", which utilize electrodynamic focusing, have been shown to effectively focus ions with mass-to-charge ratio (m/z) ranging from ~100 to 5000. Focusing efficiencies of ion funnels drop for higher m/z values because very high voltages are needed to overcome the particle inertia. Conventional "aerodynamic lenses" utilize inertia to focus down to 25 nm in diameter (~5 MDa); to date, Brownian diffusion has prevented the effective focusing of particles smaller than this. We recently reported a design procedure that should, in principle, extend focusing with aerodynamic lenses to particles as small as 3 nm (~10 kDa), thereby bridging the gap between the ion funnel and the conventional aerodynamic lenses. In this paper, we report for the first time experimental results for the performance of these new "nanolenses". Measurements were done using spherical oil droplets, proteins, and sodium chloride particles ranging in size from 3 to 30 nm diameter. We found that particle transport efficiencies from atmospheric pressure to vacuum through the aerodynamic lens system were greater than 80% for 10-30 nm particles, and greater than 50% for a ~3.8 nm protein (Lysozyme from chicken egg white, molecular weight 14.3 kDa). Particle beam diameters were about a factor of two greater than predicted by our numerical simulations, but provide clear evidence that the nanolenses effectively focus all three particle types.

  16. Applications of Electronstatic Lenses to Electron Gun and Energy Analyzers

    International Nuclear Information System (INIS)

    Sise, O.

    2004-01-01

    Focal properties and geometries are given for several types of electrostatic lens systems commonly needed in electron impact studies. One type is an electron gun which focuses electrons over a wide range of energy onto a fixed point, such as target, and the other type is an analyzer system which focuses scattered electrons of variable energy onto a fixed position, such as the entrance plane of an analyzer. There are many different types and geometries of these lenses for controlling and focusing of the electron beams. In this presentation we discussed the criteria used for the design of the electrostatic lenses associated with the electron gun and energy analyzers and determined the fundamental relationships between the operation and behaviour of multi-element electrostatic lenses, containing five, six and seven elements. The focusing of the electron beam was achieved by applying suitable voltages to the series of these lens elements, Design of the lens system for electron gun was based on our requirements that the beam at the target had a small spot size and zero beam angle, that is, afocal mode. For energy analyzer systems we considered the entrance of the hemispherical analyzer which determines the energy of the electron beam and discussed the focusing condition of this lens systems

  17. Meso-Structure in Three Strong-lensing Systems

    Science.gov (United States)

    Saha, Prasenjit; Williams, Liliya L. R.; Ferreras, Ignacio

    2007-07-01

    We map substructure in three strong-lensing systems having particularly good image data: the galaxy lens MG J0414+053 and the clusters SDSS J1004+411 and ACO 1689. Our method is to first reconstruct the lens as a pixelated mass map and then subtract off the symmetric part (in the galaxy case) or a projected Navarro-Frenk-White profile (for the cluster lenses). In all three systems we find extended irregular structures, or meso-structures, having of order 10% of the total mass. In J0414+053, the meso-structure suggests a tidal tail connecting the main lens with a nearby galaxy; however, this interpretation is tentative. In the clusters, the identification of meso-structure is more secure, especially in ACO 1689, where two independent sets of lensed images imply very similar meso-structure. In all three cases, the meso-structures are correlated with galaxies but much more extended and massive than the stellar components of single galaxies. Such extended structures cannot plausibly persist in such high-density regions without being mixed; the crossing times are too short. The meso-structures therefore appear to be merging or otherwise dynamically evolving systems.

  18. Origami with negative refractive index to generate super-lenses

    International Nuclear Information System (INIS)

    Guenneau, Fanny; Chakrabarti, Sangeeta; Guenneau, Sebastien; Ramakrishna, S Anantha

    2014-01-01

    Negative refractive index materials (NRIM) enable unique effects including superlenses with a high degree of sub-wavelength image resolution, a capability that stems from the ability of NRIM to support a host of surface plasmon states. Using a generalized lens theorem and the powerful tools of transformational optics, a variety of focusing configurations involving complementary positive and negative refractive index media can be generated. A paradigm of such complementary media are checkerboards that consist of alternating cells of positive and negative refractive index, and are associated with very singular electromagnetics. We present here a variety of multi-scale checkerboard lenses that we call origami lenses and investigate their electromagnetic properties both theoretically and computationally. Some of these meta-structures in the plane display thin bridges of complementary media, and this highly enhances their plasmonic response. We demonstrate the design of three-dimensional checkerboard meta-structures of complementary media using transformational optics to map the checkerboard onto three-dimensional corner lenses, the only restriction being that the corresponding unfolded structures in the plane are constrained by the four color-map theorem. (paper)

  19. Consumer electronic optics: how small can a lens be: the case of panomorph lenses

    Science.gov (United States)

    Thibault, Simon; Parent, Jocelyn; Zhang, Hu; Du, Xiaojun; Roulet, Patrice

    2014-09-01

    In 2014, miniature camera modules are applied to a variety of applications such as webcam, mobile phone, automotive, endoscope, tablets, portable computers and many other products. Mobile phone cameras are probably one of the most challenging parts due to the need for smaller and smaller total track length (TTL) and optimized embedded image processing algorithms. As the technology is developing, higher resolution and higher image quality, new capabilities are required to fulfil the market needs. Consequently, the lens system becomes more complex and requires more optical elements and/or new optical elements. What is the limit? How small an injection molded lens can be? We will discuss those questions by comparing two wide angle lenses for consumer electronic market. The first lens is a 6.56 mm (TTL) panoramic (180° FOV) lens built in 2012. The second is a more recent (2014) panoramic lens (180° FOV) with a TTL of 3.80 mm for mobile phone camera. Both optics are panomorph lenses used with megapixel sensors. Between 2012 and 2014, the development in design and plastic injection molding allowed a reduction of the TTL by more than 40%. This TTL reduction has been achieved by pushing the lens design to the extreme (edge/central air and material thicknesses as well as lens shape). This was also possible due to a better control of the injection molding process and material (low birefringence, haze and thermal stability). These aspects will be presented and discussed. During the next few years, we don't know if new material will come or new process but we will still need innovative people and industries to push again the limits.

  20. Angular spectra of the intrinsic galaxy ellipticity field, their observability and their impact on lensing in tomographic surveys

    Science.gov (United States)

    Schäfer, Björn Malte; Merkel, Philipp M.

    2017-09-01

    This paper describes intrinsic ellipticity correlations between galaxies, their statistical properties, their observability with future surveys and their interference with weak gravitational lensing measurements. Using an angular-momentum-based, quadratic intrinsic alignment model we derive correlation functions of the ellipticity components and project them to yield the four non-zero angular ellipticity spectra C^ɛ _E(ℓ), C^ɛ _B(ℓ), C^ɛ _C(ℓ) and C^ɛ _S(ℓ) in their generalization to tomographic surveys. For a Euclid-like survey, these spectra would have amplitudes smaller than the weak lensing effect on non-linear structures, but would constitute an important systematics. Computing estimation biases for cosmological parameters derived from an alignment-contaminated survey suggests biases of +5σw for the dark energy equation of state parameter w, -20σ _{Ω _m} for the matter density Ωm and -12σ _{σ _8} for the spectrum normalization σ8. Intrinsic alignments yield a signal that is easily observable with a survey similar to Euclid: while not independent, significances for estimates of each of the four spectra reach values of tens of σ if weak lensing and shape noise are considered as noise sources, which suggests relative uncertainties on alignment parameters at the percent level, implying that galaxy alignment mechanisms can be investigated by future surveys.

  1. LoCuSS: THE SUNYAEV–ZEL'DOVICH EFFECT AND WEAK-LENSING MASS SCALING RELATION

    International Nuclear Information System (INIS)

    Marrone, Daniel P.; Carlstrom, John E.; Gralla, Megan; Greer, Christopher H.; Hennessy, Ryan; Leitch, Erik M.; Plagge, Thomas; Smith, Graham P.; Okabe, Nobuhiro; Bonamente, Massimiliano; Hasler, Nicole; Culverhouse, Thomas L.; Hawkins, David; Lamb, James W.; Muchovej, Stephen; Joy, Marshall; Martino, Rossella; Mazzotta, Pasquale; Miller, Amber; Mroczkowski, Tony

    2012-01-01

    We present the first weak-lensing-based scaling relation between galaxy cluster mass, M WL , and integrated Compton parameter Y sph . Observations of 18 galaxy clusters at z ≅ 0.2 were obtained with the Subaru 8.2 m telescope and the Sunyaev-Zel'dovich Array. The M WL -Y sph scaling relations, measured at Δ = 500, 1000, and 2500 ρ c , are consistent in slope and normalization with previous results derived under the assumption of hydrostatic equilibrium (HSE). We find an intrinsic scatter in M WL at fixed Y sph of 20%, larger than both previous measurements of M HSE -Y sph scatter as well as the scatter in true mass at fixed Y sph found in simulations. Moreover, the scatter in our lensing-based scaling relations is morphology dependent, with 30%-40% larger M WL for undisturbed compared to disturbed clusters at the same Y sph at r 500 . Further examination suggests that the segregation may be explained by the inability of our spherical lens models to faithfully describe the three-dimensional structure of the clusters, in particular, the structure along the line of sight. We find that the ellipticity of the brightest cluster galaxy, a proxy for halo orientation, correlates well with the offset in mass from the mean scaling relation, which supports this picture. This provides empirical evidence that line-of-sight projection effects are an important systematic uncertainty in lensing-based scaling relations.

  2. Relationship Stability through Lenses of Complexity

    OpenAIRE

    Karakurt, Gunnur

    2012-01-01

    Research on relationship stability usually considers the effect of couple outcomes and individual differences on relationship stability in isolation from each other. These separate bodies of research often lead to inconsistent results. In order to better understand relationship stability and explain inconsistencies in the literature, it is important to investigate more complex models that integrate couple outcomes and behaviors with individual differences. Motivated by these considerations, w...

  3. Thermal lensing and spherical aberration in high-power transversally pumped laser rods

    International Nuclear Information System (INIS)

    Montmerle Bonnefois, A.; Gilbert, M.; Thro, P.Y.; Weulersse, J.M.

    2006-01-01

    A precise knowledge of the thermal effects in laser crystals is very important for high-power laser design, but some relevant parameters are most often neglected in their calculation. In this paper, with the example of transversally pumped, high-power Nd:YAG lasers, we show the importance of the thermal dependence of the gain medium's physical properties such as the thermal conductivity, the dn/dT and the expansion coefficient on the thermal aberration and thermal lensing values; we also prove that the choice of the resonator can influence the amount of spherical aberration. Finally, analytically calculated values are confronted to experimental values, and show a very good agreement. (authors)

  4. Seawater intrusion vulnerability indicators for freshwater lenses in strip islands

    Science.gov (United States)

    Morgan, L.; Werner, A. D.

    2014-12-01

    Freshwater lenses on small islands have been described as some of the most vulnerable aquifer systems in the world. Yet, little guidance is available regarding methods for rapidly assessing the vulnerability of freshwater lenses to the potential effects of climate change. To address this gap we employ a steady-state analytic modelling approach to develop seawater intrusion (SWI) vulnerability indicator equations. The vulnerability indicator equations quantify the propensity for SWI to occur in strip islands due to both recharge change and sea-level rise (SLR) (incorporating the effect of land surface inundation (LSI)). This work extends that of Werner et al. (2012) who developed SWI vulnerability indicator equations for unconfined and confined continental aquifers, and did not consider LSI. Flux-controlled and head-controlled conceptualisations of freshwater lenses are adopted. Under flux-controlled conditions the water table is able to rise unencumbered by land surface effects. Under head-controlled conditions the head is fixed at the centre of the lens due to, for example, centrally located topographic controls, surface water features or pumping. A number of inferences about SWI vulnerability in freshwater lenses can be made from the analysis: (1) SWI vulnerability indicators for SLR (under flux-controlled conditions) are proportional to lens thickness (or volume) and the rate of LSI and inversely proportional to island width; (2) SWI vulnerability indicators for recharge change (under flux-controlled conditions) are proportional to lens thickness (or volume) and inversely proportional to recharge; (3) SLR has greater impact under head-controlled conditions rather than flux-controlled conditions, whereas the opposite is the case for LSI and recharge change. Example applications to several case studies illustrate use of the method for rapidly ranking lenses according to vulnerability, thereby allowing for prioritisation of areas where further and more detailed SWI

  5. Data transfer through beam steering using agile lensing

    Science.gov (United States)

    Arshad, Muhammad Assad; Reza, Syed Azer; Muhammad, Ahsan

    2016-04-01

    This paper presents a data transfer scheme using multi-focus tunable lenses. The design involves the use of a standard laser source and a variable focus agile lens to steer to the laser beam that passes through the lens. In our proposed system, the beam steer angle depends on an input electrical signal which drives the tunable lens. Therefore the beam steer angle is made to follow the variations in the input electrical drive signal. This is extremely interesting for data transfer applications as the data signal can be used as the input drive signal to the lens. The laser beam is steered according to the input data voltage levels and when the beam is incident on a photo-detector of a finite size, only a fraction of its total incident optical power is received by the photo-detector. This power contribution is proportional to the fraction of the total number of photons per unit area which are incident on the active area of the detector. The remaining photons which are not incident on the photo-detector do not contribute to the received power at the photo-detector. We present the theory of beam steering through a tunable lens and present a theoretical framework which governs data transfer through the proposed method. We also present the transfer function of the proposed system which helps us to calculate its essential theoretical performance parameters such as modulation depth and bit error rates. We also present experimental results to demonstrate efficient data transfer through the proposed method. As tunable lenses are primarily deployed in motion-free multi-focus cameras hence most of the modern portable devices such as cellphones and tablets use these lenses to operate the in-built variable focus cameras that are part of these devices. Because tunable lenses are commonly present in several different portable devices, the proposed method of data transfer between two devices is highly promising as it expands the use of the already deployed tunable lenses with

  6. Static Linear Fresnel Lenses as LCPV System in a Greenhouse

    Science.gov (United States)

    Sonneveld, P. J.; Swinkels, G. L. A. M.; van Tuijl, B. A. J.; Janssen, H. J. J.; de Zwart, H. F.

    2011-12-01

    A low concentrating PV system with water cooling (LCPVT system) will result in electrical and thermal energy output from the solar energy excess entering a building or greenhouse. All the direct radiation could be converted, which corresponds to 75% of the incoming solar energy. This will significantly reduce the demand of cooling of the building. For an optimal performance it is beneficial to construct asymmetric roof elements with a steep inclination at the north side (the exact angle of course depends on the latitude of the building site). The Fresnel lens structure is oriented in upwards direction. In the current design, two of them are placed between an AR-coated double glass structure to prevent pollution and condensation on the lenses. Compared with a previous system, the number of lenses is reduced from 3 to 2 lenses, which reduces the costs of the system by limiting the number of receivers. By the upward facing of the lens structure, the focus quality is preserved over a much broader range of angles of incidence compared to a lens with downward facing structures. Each PMMA lens with a size of 1.20 m×1.60 m is composed of 12 `tiles' for easy production. The focal distance of the lens is 1,875 m and the concentration factor 50x. In most cases the focus line is thinner than 3 cm and the transmission is above 80%. The performance of these lenses with respect of the shape of the focal area and the position of the focal line has been analyzed with ray tracing techniques. From this analyses it was concluded that tracking of the receiver module is possible with two motors. One motor controls the distance between lens and receiver and one motor controls the translocation of the receivers parallel to the lens. The second conclusion was that the positions of the focal line are within the bounds of the greenhouse construction for almost the whole year. Only in winter, the focal line will be unreachable from time to time. A 480 m2 greenhouse with the LCPVT system

  7. Lense-Thirring precession around neutron stars with known spin

    Science.gov (United States)

    Van Doesburgh, Marieke; van der Klis, Michiel

    2016-07-01

    Quasi periodic oscillations (QPOs) between 300 and 1200 Hz in the X-ray emission from low mass X-ray binaries have been linked to Keplerian orbital motion at the inner edge of accretion disks. Lense-Thirring precession is precession of the line of nodes of inclined orbits with respect to the equatorial plane of a rotating object due to the general relativistic effect of frame dragging. The Lense-Thirring model of Stella and Vietri (1998) explains QPOs observed in neutron star low mass X-ray binaries at frequencies of a few tens of Hz by the nodal precession of the orbits at the inner disk edge at a precession frequency, ν_{LT} , identical to the Lense-Thirring precession of a test particle orbit. A quadratic relation between ν_{LT} and the Keplerian orbital frequency, and a linear dependence on spin frequency are predicted. In early work (van Straaten et al., 2003) this quadratic relation was confirmed to remarkable precision in three objects of uncertain spin. Since the initial work, many neutron star spin frequencies have been measured in X-ray sources that show QPOs at both low and high frequency. Using archival data from the Rossi X-ray Timing Explorer, we compare the Lense-Thirring prediction to the properties of quasi periodic oscillations measured in a sample of 14 low mass X-ray binaries of which the neutron star spin frequencies can be inferred from their bursting behaviour. We find that in the range predicted for the precession frequency, we can distinguish two different oscillations that often occur simultaneously. In previous works, these two oscillations have often been confused. For both frequencies, we find correlations with inferred Keplerian frequency characterized by power laws with indices that differ significantly from the prediction of 2.0 and therefore inconsistent with the Lense-Thirring model. Also, the specific moment of inertia of the neutron star required by the observed frequencies exceeds values predicted for realistic equations of

  8. Instance-Based Question Answering

    Science.gov (United States)

    2006-12-01

    included factoid questions grouped around a set of target entities. For example, for the target entity “ Franz Kafka ”, associated questions included: “Where...from Franz Schubert. A year later he did on Dec 5th.”). Depending on the task, an answer extractor may identify very small, factoid candidates which...IWP): Paraphrase Ac- quisition and Applications, 2003. [55] A. Ittycheriah, M. Franz , and S. Roukos. Ibm’s statistical question answering system - trec

  9. Surface interactions on hydrogel extended wear contact lenses: microflora and microfauna.

    Science.gov (United States)

    Hart, D E; Shih, K L

    1987-10-01

    The microbial flora and fauna of 25 high water content nonionic "soft" contact lenses worn by patients on an extended wear basis, 4 hand-cleaned patient-worn lenses, and 4 improperly maintained lenses were compared. Almost all the patient-worn lenses (24 of 25) were free of viable microorganisms, whereas all the hand-cleaned lenses (4 of 4) were contaminated with different microorganisms. This study showed that hand contact is a major source of microbial contamination of a lens and that usually the hand-transported microorganisms do not survive permanently on the lens in a healthy, normal eye. Improperly maintained lenses demonstrated pathogenic microbial associations. Proof of the eye's potent antimicrobial environment was demonstrated. Thus, microorganism-lens associations are largely due to lens handling and inappropriate maintenance regimens. Typically there are few microorganisms on an extended wear soft lens while it is being worn.

  10. A novel method of fitting scleral lenses using high resolution optical coherence tomography.

    Science.gov (United States)

    Gemoules, Greg

    2008-03-01

    Case report study of a novel method of fitting large rigid gas-permeable lenses (cornea-scleral, mini-scleral, scleral). Nine patients with different corneal and refractive conditions were fitted with scleral-type rigid gas-permeable lenses using high resolution ocular coherence tomography. All patients achieved excellent visual acuity and comfort. Lenses were well tolerated without significant complications. Three cases are discussed in detail. Two of the 3 patients had previously undergone fitting with trial lenses so that the different methods could be compared with respect to number of lenses used to achieve a final fit. High resolution biometry proved to be a highly useful fitting tool and seems to offer a more accurate and efficient alternative to fitting scleral-type lenses compared with the trial lens method.

  11. Efficacy of progressive addition lenses in the treatment of ametropia after the single eye's IOL implantation.

    Science.gov (United States)

    Chen, Lin Xing; Zeng, Ying Yu; Zeng, Jun Wen; He, Ming Guang

    2012-09-01

    To investigate the efficacy of progressive addition lenses on the treatment of ametropia and loss of accomodation after the single eye's IOL implantation. Eighty four patients undergoing IOL implantation in single eyes were prescribed with progressive addition lenses for ametropia correction and regularly followed up to observe subsequent correction effect. Among these 84 patients, 72 could comfortably adapt to the use of progressive addition lenses to improve visual acuity and accomondation, while the remaining 12 patients failed to accomodate the usage of progressive addition lenses. Wearing progressive addition lenses acts as a relatively feasible approach to improve visual acuity and alleviate disorders of accomodation for patients who underwent IOL implantation in single eyes. The patients should be prescribed with progressive lenses under professional instructions and guidance.

  12. Interpreting the Strongly Lensed Supernova iPTF16geu: Time Delay Predictions, Microlensing, and Lensing Rates

    Energy Technology Data Exchange (ETDEWEB)

    More, Anupreeta; Oguri, Masamune; More, Surhud [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), University of Tokyo, Chiba 277-8583 (Japan); Suyu, Sherry H. [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild-Str. 1, D-85748 Garching (Germany); Lee, Chien-Hsiu, E-mail: anupreeta.more@ipmu.jp [Subaru Telescope, National Astronomical Observatory of Japan, 650 North Aohoku Place, Hilo, HI 96720 (United States)

    2017-02-01

    We present predictions for time delays between multiple images of the gravitationally lensed supernova, iPTF16geu, which was recently discovered from the intermediate Palomar Transient Factory (iPTF). As the supernova is of Type Ia where the intrinsic luminosity is usually well known, accurately measured time delays of the multiple images could provide tight constraints on the Hubble constant. According to our lens mass models constrained by the Hubble Space Telescope F814W image, we expect the maximum relative time delay to be less than a day, which is consistent with the maximum of 100 hr reported by Goobar et al. but places a stringent upper limit. Furthermore, the fluxes of most of the supernova images depart from expected values suggesting that they are affected by microlensing. The microlensing timescales are small enough that they may pose significant problems to measure the time delays reliably. Our lensing rate calculation indicates that the occurrence of a lensed SN in iPTF is likely. However, the observed total magnification of iPTF16geu is larger than expected, given its redshift. This may be a further indication of ongoing microlensing in this system.

  13. Bayesian galaxy shape measurement for weak lensing surveys - III. Application to the Canada-France-Hawaii Telescope Lensing Survey

    Science.gov (United States)

    Miller, L.; Heymans, C.; Kitching, T. D.; van Waerbeke, L.; Erben, T.; Hildebrandt, H.; Hoekstra, H.; Mellier, Y.; Rowe, B. T. P.; Coupon, J.; Dietrich, J. P.; Fu, L.; Harnois-Déraps, J.; Hudson, M. J.; Kilbinger, M.; Kuijken, K.; Schrabback, T.; Semboloni, E.; Vafaei, S.; Velander, M.

    2013-03-01

    A likelihood-based method for measuring weak gravitational lensing shear in deep galaxy surveys is described and applied to the Canada-France-Hawaii Telescope (CFHT) Lensing Survey (CFHTLenS). CFHTLenS comprises 154 deg2 of multi-colour optical data from the CFHT Legacy Survey, with lensing measurements being made in the i' band to a depth i'AB noise ratio νSN ≳ 10. The method is based on the lensfit algorithm described in earlier papers, but here we describe a full analysis pipeline that takes into account the properties of real surveys. The method creates pixel-based models of the varying point spread function (PSF) in individual image exposures. It fits PSF-convolved two-component (disc plus bulge) models to measure the ellipticity of each galaxy, with Bayesian marginalization over model nuisance parameters of galaxy position, size, brightness and bulge fraction. The method allows optimal joint measurement of multiple, dithered image exposures, taking into account imaging distortion and the alignment of the multiple measurements. We discuss the effects of noise bias on the likelihood distribution of galaxy ellipticity. Two sets of image simulations that mirror the observed properties of CFHTLenS have been created to establish the method's accuracy and to derive an empirical correction for the effects of noise bias.

  14. Commonly Asked Questions in Thermodynamics

    CERN Document Server

    Assael, Marc J

    2011-01-01

    Have you ever had a question that keeps persisting and for which you cannot find a clear answer? Is the question seemingly so "simple" that the problem is glossed over in most resources, or skipped entirely? CRC Press/Taylor and Francis is pleased to introduce Commonly Asked Questions in Thermodynamics, the first in a new series of books that address the questions that frequently arise in today's major scientific and technical disciplines. Designed for a wide audience, from students and researchers to practicing professionals in related areas, the books are organized in a user friend

  15. Questioning Questions: Elementary Teachers' Adaptations of Investigation Questions Across the Inquiry Continuum

    Science.gov (United States)

    Biggers, Mandy

    2018-02-01

    Questioning is a central practice in science classrooms. However, not every question translates into a "good" science investigation. Questions that drive science investigations can be provided by many sources including the teacher, the curriculum, or the student. The variations in the source of investigation questions were explored in this study. A dataset of 120 elementary science classroom videos and associated lesson plans from 40 elementary teachers (K-5) across 21 elementary school campuses were scored on an instrument measuring the amount of teacher-direction or student-direction of the lessons' investigation questions. Results indicated that the investigation questions were overwhelmingly teacher directed in nature, with no opportunities for students to develop their own questions for investigation. This study has implications for researchers and practitioners alike, calling attention to the teacher-directed nature of investigation questions in existing science curriculum materials, and the need for teacher training in instructional strategies to adapt their existing curriculum materials across the continuum of teacher-directed and student-directed investigation questions. Teachers need strategies for adapting the teacher-directed questions provided in their existing curriculum materials in order to allow students the opportunity to engage in this essential scientific practice.

  16. Ability of silver-impregnated contact lenses to control microbial growth and colonisation

    OpenAIRE

    Mark D.P. Willcox; Emma B.H. Hume; Ajay K. Vijay; Robert Petcavich

    2010-01-01

    Purpose: To examine the ability of silver nano-particles to prevent the growth of Pseudomonas aeruginosa and Staphylococcus aureus in solution or when adsorbed into contact lenses. To examine the ability of silver nano-particles to prevent the growth of Acanthamoeba castellanii. Methods: Etafilcon A lenses were soaked in various concentrations of silver nano-particles. Bacterial cells were then exposed to these lenses, and numbers of viable cells on lens surface or in solution compared to ...

  17. Mapping the distribution of luminous and dark matter in strong lensing galaxies

    OpenAIRE

    Ferreras, I.; Saha, P.; Williams, L. L. R.; Burles, S.

    2007-01-01

    We present the distribution of luminous and dark matter in a set of strong lensing (early-type) galaxies. By combining two independent techniques – stellar population synthesis and gravitational lensing – we can compare the baryonic and dark matter content in these galaxies within the regions that can be probed using the images of the lensed background source. Two samples were studied, extracted from the CASTLES and SLACS surveys. The former probes a wider range of redshifts and allows us to ...

  18. Questions

    DEFF Research Database (Denmark)

    Larsen, Steen Nepper

    2012-01-01

    Bidrag til festskrift til Jesper Hoffmeyer i anledning af hans 70 års dag i Don Favineau, Paul Cobley & Kalevi Kull (eds.): "A More Developed Sign. Interpreting the Work of Jesper Hoffmeyer". Antologien udg. som særnummer af Tartu Semiotics Library Nr. 10 og mit bidrag forefindes på p. 217-220....

  19. Dog Bite Reflections--Socratic Questioning Revisited

    Science.gov (United States)

    Toledo, Cheri A.

    2015-01-01

    In the online environment, the asynchronous discussion is an important tool for creating community, developing critical thinking skills, and checking for understanding. As students learn how to use Socratic questions for effective interactions, the discussion boards can become the most exciting part of the course. This sequel to the article…

  20. Transnational aspects of the Kurdish question

    NARCIS (Netherlands)

    Bruinessen, M.M. van

    2000-01-01

    Simplifying a complex question, one may observe that the objectives of all Kurdish political movements of the past century have concerned two central issues, culture and territory. The Kurdish language and the region historically known as Kurdistan are the Kurds’ most important national symbols.

  1. The Miracle Question & Therapy with College Students.

    Science.gov (United States)

    Santa Rita, Emilio

    Solution-focused therapy is based on the premise that client goals and solutions are more important than problems the client depicts in sessions. The miracle question technique is used in the first session to help the client construct and consider a future without the problem: "Suppose that one night, while you were asleep, there was a…

  2. Children Ask Questions about West African Art.

    Science.gov (United States)

    Abercrombie, Denice; Cochran, Mathilda; Mims, Margaret

    1997-01-01

    Presents a collection of questions that fifth-grade students asked about African artwork and answers provided by staff from the Museum of Fine Arts in Houston, Texas. Observes that students' interest in important visual aspects of the art creates lead-ins to more detailed discussions of West African art and culture. (DSK)

  3. Teaching Children with Autism to Ask Questions

    Science.gov (United States)

    Squires, Katie E.; Bickel, Alyssa

    2015-01-01

    Children with autism have impairments in communication that make it difficult for them to acquire the ability to ask appropriate wh- questions. This is a very important skill, and one that clinicians often do not know how to target. Search terms were entered into several databases to locate studies published in peer-reviewed journals. The studies…

  4. Effect of adhered bacteria on the binding of Acanthamoeba to hydrogel lenses.

    Science.gov (United States)

    Gorlin, A I; Gabriel, M M; Wilson, L A; Ahearn, D G

    1996-05-01

    To determine the effect of Pseudomonas aeruginosa and Staphylococcus epidermidis on the binding of Acanthamoeba species to hydrogel lenses. Cells of amebae and bacteria were incubated with different types of hydrogel lenses. Densities of amebae that were bound to the lenses after rinsing were determined from direct counts with a cell detachment procedure and from scintillation counts of cells, which were radiolabeled with tritiated leucine. With both methods, amebae showed significantly increased binding to hydrogel lenses with attached P aeruginosa. The numbers of amebae that were retained on lenses with attached S epidermidis were not significantly different from those that were retained on lenses without bacteria. The binding of amebae to unworn hydrogel lenses, in contrast to the irreversible adherence of P aeruginosa, was tenuous. The binding of Acanthamoeba species to unworn hydrogel lenses was tenuous and appeared to be related to water content, surface tensions, and ionic charge. The presence of adhered P aeruginosa on the hydrogel lenses facilitated the binding of Acanthamoeba species. The cocontamination of lens systems with bacteria (eg, P aeruginosa) may be a prime factor in the development of amebic keratitis.

  5. Fabricating low cost and high performance elastomer lenses using hanging droplets.

    Science.gov (United States)

    Lee, W M; Upadhya, A; Reece, P J; Phan, Tri Giang

    2014-05-01

    Existing methods for low cost lenses using parallel mold stamping and high temperature reflow requires complex engineering controls to produce high quality lenses. These manufacturing techniques rely on expensive equipment. In this paper, we propose a low cost (technique heralds a new paradigm in the manufacture of low cost, high performance optical lenses for the masses. Using these lenses, we were able to transform an ordinary commercial smartphone camera into a low-cost digital dermascope (60x magnification) that can readily visualize microscopic structures on skin such as sweat pores.

  6. Scleral Lenses in the Management of Corneal Irregularity and Ocular Surface Disease.

    Science.gov (United States)

    Shorter, Ellen; Harthan, Jennifer; Nau, Cherie B; Nau, Amy; Barr, Joseph T; Hodge, David O; Schornack, Muriel M

    2017-09-29

    To describe current practice patterns regarding the use of scleral lens therapy in the management of corneal irregularity and ocular surface disease among eye care providers who fit scleral lenses. The Scleral Lenses in Current Ophthalmic Practice: an Evaluation (SCOPE) study group conducted an electronic survey of eye care providers from January 15 to March 31, 2015. Respondents ranked management options for corneal irregularity in the order in which they would generally consider their use. Respondents also ranked options for the management of ocular surface disease in the order in which they would use each of the treatments. Results for each option were analyzed as percentage first-place ranking; percentage first-, second-, or third-place ranking; and mean rank score. Survey responses were obtained from 723 providers who had fit 5 or more scleral lenses. Of these respondents, 629 ranked options for management of corneal irregularity and 612 ranked options for management of ocular surface disease. Corneal rigid gas-permeable lenses were the first option for management of corneal irregularity for 44% of respondents, and scleral lenses were the first option for 34% of respondents. Lubricant drops were the first therapeutic recommendation for ocular surface disease for 84% of respondents, and scleral lenses were ranked first by 6% of respondents. Scleral lenses rank second only to corneal rigid gas-permeable lenses for management of corneal irregularity. Scleral lenses are generally considered after other medical intervention and before surgery for the management of ocular surface disease.

  7. Influence of Tear Protein Deposition on the Oxygen Permeability of Soft Contact Lenses

    Directory of Open Access Journals (Sweden)

    Se Eun Lee

    2017-01-01

    Full Text Available Purpose. To investigate the effect of tear protein deposition on the change in oxygen permeability (Dk of soft contact lenses (SCL. Methods. Three hydrogel lenses (polymacon, nelfilcon A, and etafilcon A and two silicon hydrogel lenses (lotrafilcon A and balafilcon A were investigated. Etafilcon A lenses were incubated in artificial tear solution for 1, 6, 12, and 48 h, whereas the other SCL were incubated for 1, 3, 7, and 14 days. Oxygen permeability was measured using the polarographic method, and lenses were stacked in four layers to correct the boundary effect. Results. The Dk of all investigated SCL was decreased by the protein deposition. Silicone hydrogel lenses showed a smaller deposition of artificial tear proteins than conventional hydrogel lenses. However, their Dk was reduced twofold than those of 3 conventional hydrogel lenses when compared at the same level of protein deposition. Despite a large amount of total deposited protein in etafilcon A lenses, their Dk was more stable than other SCL. Conclusions. From the results, it was revealed that the Dk of SCL is different from the value provided by manufacturers because of the tear protein deposition on surface and/or in pore of SCL; however, the degree of Dk change in SCL was not simply correlated with the amount of tear protein deposition. Thus, it is considered that the correlation between tear protein deposition and properties of lens materials affects Dk change.

  8. Questions of Representations in Architecture

    DEFF Research Database (Denmark)

    2015-01-01

    Questions of Representations in Architecture is the first major Danish contribution to the current international discussion on architects' use of representations and the significance of visual media for architecture.......Questions of Representations in Architecture is the first major Danish contribution to the current international discussion on architects' use of representations and the significance of visual media for architecture....

  9. Some of the unanswered questions in finance

    Directory of Open Access Journals (Sweden)

    Đurić Dragana M.

    2006-01-01

    Full Text Available A very dynamic development of finance in the last 50 years is inter alia probably due to experiments and innovations in this field. Previously theoretical base could not explain and predict movements especially in volatile times. "The new finance" appeared 50 years ago (portfolio theory CAPM, the efficient market theory, M&M theorem and made substantial progress in understanding movements in globalized and internationalized financial markets. However, many questions remain open. The author tries to put emphasis on some of these questions, perfectly aware that these are not the only ones. Unresolved questions are related to company's aims, project's risks, degree of portfolio optimization, importance of liquidity, dividend policy, as well as factors that determine M&A. As the "new finance" is not able to predict and explain volatile movements, a question that should be posed is whether it is appropriate to add some non-economic factors as the behaviorist theory suggests. Although the behaviorist theory is an important part of "new finance", it is unfortunately the only theory able to explain movements in volatile times. In conclusion, many questions still remain unanswered and wait for appropriate theoretical explanations.

  10. Key questions and challenges in angiosperm macroevolution.

    Science.gov (United States)

    Sauquet, Hervé; Magallón, Susana

    2018-03-25

    Contents Summary I. Introduction II. Six key questions III. Three key challenges IV. Conclusions Acknowledgements References SUMMARY: The origin and rapid diversification of angiosperms (flowering plants) represent one of the most intriguing topics in evolutionary biology. Despite considerable progress made in complementary fields over the last two decades (paleobotany, phylogenetics, ecology, evo-devo, genomics), many important questions remain. For instance, what has been the impact of mass extinctions on angiosperm diversification? Are the angiosperms an adaptive radiation? Has morphological evolution in angiosperms been gradual or pulsed? We propose that the recent and ongoing revolution in macroevolutionary methods provides an unprecedented opportunity to explore long-standing questions that probably hold important clues to understand present-day biodiversity. We present six key questions that explore the origin and diversification of angiosperms. We also identify three key challenges to address these questions: (1) the development of new integrative models that include diversification, multiple intrinsic and environmental traits, biogeography and the fossil record all at once, whilst accounting for sampling bias and heterogeneity of macroevolutionary processes through time and among lineages; (2) the need for large and standardized synthetic databases of morphological variation; and (3) continuous effort on sampling the fossil record, but with a revolution in current paleobotanical practice. © 2018 Royal Botanic Gardens and Domain Trust New Phytologist © 2018 New Phytologist Trust.

  11. Importance measures

    International Nuclear Information System (INIS)

    Gomez Cobo, A.

    1997-01-01

    The presentation discusses the following: general concepts of importance measures; example fault tree, used to illustrate importance measures; Birnbaum's structural importance; criticality importance; Fussel-Vesely importance; upgrading function; risk achievement worth; risk reduction worth

  12. FluidCam 1&2 - UAV-based Fluid Lensing Instruments for High-Resolution 3D Subaqueous Imaging and Automated Remote Biosphere Assessment of Reef Ecosystems

    Science.gov (United States)

    Chirayath, V.; Instrella, R.

    2016-02-01

    We present NASA ESTO FluidCam 1 & 2, Visible and NIR Fluid-Lensing-enabled imaging payloads for Unmanned Aerial Vehicles (UAVs). Developed as part of a focused 2014 earth science technology grant, FluidCam 1&2 are Fluid-Lensing-based computational optical imagers designed for automated 3D mapping and remote sensing of underwater coastal targets from airborne platforms. Fluid Lensing has been used to map underwater reefs in 3D in American Samoa and Hamelin Pool, Australia from UAV platforms at sub-cm scale, which has proven a valuable tool in modern marine research for marine biosphere assessment and conservation. We share FluidCam 1&2 instrument validation and testing results as well as preliminary processed data from field campaigns. Petabyte-scale aerial survey efforts using Fluid Lensing to image at-risk reefs demonstrate broad applicability to large-scale automated species identification, morphology studies and reef ecosystem characterization for shallow marine environments and terrestrial biospheres, of crucial importance to improving bathymetry data for physical oceanographic models and understanding climate change's impact on coastal zones, global oxygen production, carbon sequestration.

  13. Fluid Lensing, Applications to High-Resolution 3D Subaqueous Imaging & Automated Remote Biosphere Assessment from Airborne and Space-borne Platforms

    Science.gov (United States)

    Chirayath, V.

    2014-12-01

    Fluid Lensing is a theoretical model and algorithm I present for fluid-optical interactions in turbulent flows as well as two-fluid surface boundaries that, when coupled with an unique computer vision and image-processing pipeline, may be used to significantly enhance the angular resolution of a remote sensing optical system with applicability to high-resolution 3D imaging of subaqueous regions and through turbulent fluid flows. This novel remote sensing technology has recently been implemented on a quadcopter-based UAS for imaging shallow benthic systems to create the first dataset of a biosphere with unprecedented sub-cm-level imagery in 3D over areas as large as 15 square kilometers. Perturbed two-fluid boundaries with different refractive indices, such as the surface between the ocean and air, may be exploited for use as lensing elements for imaging targets on either side of the interface with enhanced angular resolution. I present theoretical developments behind Fluid Lensing and experimental results from its recent implementation for the Reactive Reefs project to image shallow reef ecosystems at cm scales. Preliminary results from petabyte-scale aerial survey efforts using Fluid Lensing to image at-risk coral reefs in American Samoa (August, 2013) show broad applicability to large-scale automated species identification, morphology studies and reef ecosystem characterization for shallow marine environments and terrestrial biospheres, of crucial importance to understanding climate change's impact on coastal zones, global oxygen production and carbon sequestration.

  14. The question of caution in professional medium

    International Nuclear Information System (INIS)

    Godard, O.

    2006-01-01

    Contrived in Europe to tackle the environment protection policies and management of natural resources, the principle of caution has seen since 1990 its interest developed towards the fields of food safety and public health. The importance and the relevance of questions have lead the national institute of research and safety to constitute a working group to explore the problems and the potentialities that could be linked to the explicit introduction of this principle and this in the field of the prevention of professional risks. This work tackles several aspects of the question of caution in professional medium such history, concepts, evolution...as well as cases judged exemplary ones. (N.C.)

  15. Multifocal versus monofocal intraocular lenses after cataract extraction

    Directory of Open Access Journals (Sweden)

    Daniel Calladine

    Full Text Available BACKGROUND: Good unaided distance visual acuity is now a realistic expectation following cataract surgery and intraocular lens (IOL implantation. Near vision, however, still requires additional refractive power, usually in the form of reading glasses. Multiple optic (multifocal IOLs are available which claim to allow good vision at a range of distances. It is unclear whether this benefit outweighs the optical compromises inherent in multifocal IOLs. OBJECTIVES: The objective of this review was to assess the effects of multifocal IOLs, including effects on visual acuity, subjective visual satisfaction, spectacle dependence, glare and contrast sensitivity, compared to standard monofocal lenses in people undergoing cataract surgery. METHODS: Search methods: We searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register, The Cochrane Library 2012, Issue 2, MEDLINE (January 1946 to March 2012, EMBASE (January 1980 to March 2012, the metaRegister of Controlled Trials (mRCT (www.controlled-trials.com, ClinicalTrials.gov (www.clinicaltrials.gov and the WHO International Clinical Trials Registry Platform (ICTRP (www.who.int/ictrp/search/en. We did not use any date or language restrictions in the electronic searches for trials. The electronic databases were last searched on 6 March 2012. We searched the reference lists of relevant articles and contacted investigators of included studies and manufacturers of multifocal IOLs for information about additional published and unpublished studies. Selection criteria: All randomised controlled trials comparing a multifocal IOL of any type with a monofocal IOL as control were included. Both unilateral and bilateral implantation trials were included. Data collection and analysis: Two authors collected data and assessed trial quality. Where possible, we pooled data from the individual studies using a random-effects model, otherwise we tabulated data. MAIN RESULTS: Sixteen completed trials

  16. Experimental study of the fabrication of chalcogenide glass lenses by using precision glass molding

    International Nuclear Information System (INIS)

    Cha, Du Hwan; Kim, Jeong Ho; Kim, Hye Jeong

    2014-01-01

    Although the development of small formats (640 x 480 pixel arrays) and amorphous silicon microbolometers has greatly decreased detector cost, another important component of a thermal camera, the optics, still prohibit a breakthrough for high-volume commercial systems. The aspheric lenses used in thermal imaging are typically made using the costly single-point diamond turning (SPDT) process with expensive single-crystal materials (Ge, ZnS, etc.). As a potential solution to reduce cost, the compression molding method using chalcogenide glass has become attractive for fabricating IR optics. The present paper reports the fabrication of a mold and a molded chalcogenide glass lens for a thermal security camera. In addition, the molded chalcogenide glass lens was evaluated using the form error, roughness and decentration for each surface of the molded lens. From the evaluation results, we verified that the molded lens was capable of being used for thermal imaging applications.

  17. Modelling the line-of-sight contribution in substructure lensing

    Science.gov (United States)

    Despali, Giulia; Vegetti, Simona; White, Simon D. M.; Giocoli, Carlo; van den Bosch, Frank C.

    2018-04-01

    We investigate how Einstein rings and magnified arcs are affected by small-mass dark-matter haloes placed along the line of sight to gravitational lens systems. By comparing the gravitational signature of line-of-sight haloes with that of substructures within the lensing galaxy, we derive a mass-redshift relation that allows us to rescale the detection threshold (i.e. lowest detectable mass) for substructures to a detection threshold for line-of-sight haloes at any redshift. We then quantify the line-of-sight contribution to the total number density of low-mass objects that can be detected through strong gravitational lensing. Finally, we assess the degeneracy between substructures and line-of-sight haloes of different mass and redshift to provide a statistical interpretation of current and future detections, with the aim of distinguishing between cold dark matter and warm dark matter. We find that line-of-sight haloes statistically dominate with respect to substructures, by an amount that strongly depends on the source and lens redshifts, and on the chosen dark-matter model. Substructures represent about 30 percent of the total number of perturbers for low lens and source redshifts (as for the SLACS lenses), but less than 10 per cent for high-redshift systems. We also find that for data with high enough signal-to-noise ratio and angular resolution, the non-linear effects arising from a double-lens-plane configuration are such that one is able to observationally recover the line-of-sight halo redshift with an absolute error precision of 0.15 at the 68 per cent confidence level.

  18. Predicting estimates of oxygen transmissibility for scleral lenses.

    Science.gov (United States)

    Michaud, Langis; van der Worp, Eef; Brazeau, Daniel; Warde, Richard; Giasson, Claude J

    2012-12-01

    Although scleral contact lenses are prescribed with increasing frequency, little is known about their long-term effects on ocular physiology. The main goal of this paper is to predict values of oxygen transmissibility of scleral lens systems by applying the concept of resistors in series to parameters characteristic of current scleral lenses. A second aim is to find the maximal lens and post-lens tear layer thickness combinations above which hypoxia-induced corneal swelling would be found. Theoretical calculations were used to predict the oxygen transmissibility of scleral lens systems, considering several material permeabilities (Dks 100-170), varying lens thicknesses (250-500 μm), the known tear permeability (Dk of 80) and expected post-lens tear layer thicknesses (100-400 μm). The Holden-Mertz Dk/t criteria of 24 Fatt units for the central cornea and the Harvitt-Bonanno criteria of 35 Fatt units for the limbal area were used as reference points. Our calculations of oxygen transmissibility, with varying tear layer and lens thicknesses, ranged from 10 to 36.7 at the scleral lens centers and from 17.4 to 62.6 at the peripheries. Our calculations of maximum central lens thicknesses show a practical range of 250-495 μm, in conjunction with a post-lens tear layer thickness of 100-250 μm. Our computations show that most modern scleral lenses, with recommended fitting techniques, should lead to some level of hypoxia-induced corneal swelling. Recommendations are made to minimize hypoxia-induced corneal swelling: highest Dk available (>150) lens with a maximal central thickness of 250 μm and fitted with a clearance that does not exceed 200 μm. Copyright © 2012 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  19. Effect of time and washing on the adhesion of Acanthamoeba to extended wear disposable hydrogel contact lenses.

    Science.gov (United States)

    Ramachandran, L; Janakiraman, D; Sharma, S; Rao, G N

    1997-04-01

    This study was undertaken to determine the extent of adhesion of cysts and trophozoites of Acanthamoeba to worn disposable hydrogel lenses and to study the effect of time, lens material, and washing on the adhesion. Etafilcon A (58% water content) and Polymacon (38% water content) lenses worn on a 6 night extended wear basis and collected aseptically in PBS pH 7.2, were used for the study. Unworn lenses of the same materials were used as controls. Segments of lenses were incubated in Acanthamoeba suspension (cysts and trophozoites) and examined at 0, 5, and 24 hours, either washed or unwashed, for adherent Acanthamoeba. The amoebae adherent per square mm surface of the lens were enumerated. Levels of adhesion in various groups were compared using Wilcoxon sign rank test. At 0 hours, unwashed worn Polymacon lenses showed significantly greater adherence than Etafilcon A lenses compared to the controls (P = 0.0469). However, there was no difference at 5 and 24 hours exposure time between the lenses. At 24 hours the adhesion of Acanthamoeba was greater for washed worn lenses of both types compared to washed lenses of controls (P = 0.002, 0.012). Amoebae adhered with equal affinity to both types of lenses but adhered with greater affinity to worn lenses than unworn lenses. Adhesion of Acanthamoeba to worn disposable lenses may be a factor in the pathogenesis of Acanthamoeba keratitis in disposable lens wearers.

  20. Effect of yellow-tinted lenses on visual attributes related to sports activities.

    Science.gov (United States)

    Kohmura, Yoshimitsu; Murakami, Shigeki; Aoki, Kazuhiro

    2013-03-01

    The purpose of this study was to clarify the effect of colored lenses on visual attributes related to sports activities. The subjects were 24 students (11 females, 13 males; average age 21.0 ±1.2 years) attending a sports university. Lenses of 5 colors were used: colorless, light yellow, dark yellow, light gray, and dark gray. For each lens, measurements were performed in a fixed order: contrast sensitivity, dynamic visual acuity, depth perception, hand-eye coordination and visual acuity and low-contrast visual acuity. The conditions for the measurements of visual acuity and low-contrast visual acuity were in the order of Evening, Evening+Glare, Day, and Day+Glare. There were no significant differences among lenses in dynamic visual acuity and depth perception. For hand-eye coordination, time was significantly shorter with colorless than dark gray lenses. Contrast sensitivity was significantly higher with colorless, light yellow, and light gray lenses than with dark yellow and dark gray lenses. The low-contrast visual acuity test in the Day+Glare condition showed no significant difference among the lenses. In the Evening condition, low-contrast visual acuity was significantly higher with colorless and light yellow lenses than with dark gray lenses, and in the Evening+Glare condition, low-contrast visual acuity was significantly higher with colorless lenses than with the other colors except light yellow. Under early evening conditions and during sports activities, light yellow lenses do not appear to have an adverse effect on visual attributes.

  1. Effect of xylose on the synthesis of phosphorylcholine and phosphorylethanolamine in rat lenses.

    Science.gov (United States)

    Jernigan, H M; Ekambaram, M C; Blum, P S; Blanchard, M S

    1993-03-01

    Choline, an essential phospholipid precursor, enters the lens by a facilitated transport system and is phosphorylated to form phosphorylcholine (P-choline). Intact lenses incubated with [3H]choline accumulate both [3H]choline and P-[3H]choline. The rate and extent of this accumulation have been used to study the effects of osmotic or oxidative cataractogenic stress, and also to test the ability of compounds to protect lenses from stress-related damage. The initial effect of oxidative stress on choline metabolism is decreased choline transport, but the mechanism by which osmotic stress affects the accumulation of [3H]choline is not understood. The effects of osmotic and oxidative stress on choline influx and metabolism were compared in rat lenses incubated in TC-199 medium. After osmotic stress by incubation with 30 mM xylose for up to 24 hr, lenses accumulated the same amount of radiolabel as controls during a 30 min pulse with [3H]choline. However, if the lenses were exposed to [3H]choline for 6 hr so that accumulation of radiolabel in the lenses was limited by the rate of P-choline synthesis, xylose treated lenses accumulated less choline than controls. Separation of the lenticular radiolabel into [3H]choline and P-[3H]choline confirmed that xylose decreased synthesis of P-choline, although adequate unphosphorylated [3H]choline was available in the lenses. A decrease in P-[3H]ethanolamine synthesis was also seen in xylose-treated lenses incubated with [3H]ethanolamine. Ethanolamine can enter lenses by a non-saturable process which is not dependent upon a transporter. Although xylose decreased P-choline synthesis in intact lenses, neither xylose nor xylitol inhibited choline kinase in lens homogenates.(ABSTRACT TRUNCATED AT 250 WORDS)

  2. [Scheimpflug photography for the examination of phakic intraocular lenses].

    Science.gov (United States)

    Baumeister, M

    2014-10-01

    High myopia phakic intraocular lenses (IOL) have become an established means of surgical correction for high ametropia. Scheimpflug photography is one of the methods which are frequently applied for postoperative examination of the implants. Results from published studies employing Scheimpflug photography for examination of anterior chamber angle-fixated, iris-fixated and sulcus-fixated phakic IOLs were evaluated. In several published studies Scheimpflug photography was used to examine the position of the implant and opacification of the crystalline lens. The results provided valuable evidence for the improvement of phakic IOL design. Scheimpflug photography offers an easy to use, rapid non-contact examination of phakic IOLs.

  3. A Conceptual and Cultural History of Gravitational Lensing

    Science.gov (United States)

    Valls-Gabaud, D.

    2009-08-01

    By analysing the early ideas on the bending of light due to a gravitational attraction, which led to the concept of gravitational lenses, we attempt to present an undistorted historical and cultural perspective of the subject. We show that, contrary to a widespread belief, Newton did not ponder on this topic, and that the earliest thoughts possibly come from Marat and Cavendish. We briefly review the contributions by Soldner, Chwolson and Einstein and focus on the rôle of F. Link, who was undoubtedly the pioneer of the subject.

  4. Planck 2013 results. XVIII. Gravitational lensing-infrared background correlation

    CERN Document Server

    Ade, P.A.R.; Armitage-Caplan, C.; Arnaud, M.; Ashdown, M.; Atrio-Barandela, F.; Aumont, J.; Baccigalupi, C.; Banday, A.J.; Barreiro, R.B.; Bartlett, J.G.; Basak, S.; Battaner, E.; Benabed, K.; Benoit, A.; Benoit-Levy, A.; Bernard, J.P.; Bersanelli, M.; Bethermin, M.; Bielewicz, P.; Bobin, J.; Bock, J.J.; Bonaldi, A.; Bond, J.R.; Borrill, J.; Bouchet, F.R.; Boulanger, F.; Bridges, M.; Bucher, M.; Burigana, C.; Butler, R.C.; Cardoso, J.F.; Catalano, A.; Challinor, A.; Chamballu, A.; Chiang, L.Y.; Chiang, H.C.; Christensen, P.R.; Church, S.; Clements, D.L.; Colombi, S.; Colombo, L.P.L.; Couchot, F.; Coulais, A.; Crill, B.P.; Curto, A.; Cuttaia, F.; Danese, L.; Davies, R.D.; de Bernardis, P.; de Rosa, A.; de Zotti, G.; Delabrouille, J.; Delouis, J.M.; Desert, F.X.; Diego, J.M.; Dole, H.; Donzelli, S.; Dore, O.; Douspis, M.; Dupac, X.; Efstathiou, G.; Ensslin, T.A.; Eriksen, H.K.; Finelli, F.; Forni, O.; Frailis, M.; Franceschi, E.; Galeotta, S.; Ganga, K.; Giard, M.; Giardino, G.; Giraud-Heraud, Y.; Gonzalez-Nuevo, J.; Gorski, K.M.; Gratton, S.; Gregorio, A.; Gruppuso, A.; Gudmundsson, J.E.; Hansen, F.K.; Hanson, D.; Harrison, D.; Henrot-Versille, S.; Hernandez-Monteagudo, C.; Herranz, D.; Hildebrandt, S.R.; Hivon, E.; Hobson, M.; Holmes, W.A.; Hornstrup, A.; Hovest, W.; Huffenberger, K.M.; Jaffe, T.R.; Jaffe, A.H.; Jones, W.C.; Juvela, M.; Keihanen, E.; Keskitalo, R.; Kisner, T.S.; Kneissl, R.; Knoche, J.; Knox, L.; Kunz, M.; Kurki-Suonio, H.; Lacasa, F.; Lagache, G.; Lahteenmaki, A.; Lamarre, J.M.; Lasenby, A.; Laureijs, R.J.; Lawrence, C.R.; Leonardi, R.; Leon-Tavares, J.; Lesgourgues, J.; Liguori, M.; Lilje, P.B.; Linden-Vornle, M.; Lopez-Caniego, M.; Lubin, P.M.; Macias-Perez, J.F.; Maffei, B.; Maino, D.; Mandolesi, N.; Maris, M.; Marshall, D.J.; Martin, P.G.; Martinez-Gonzalez, E.; Masi, S.; Matarrese, S.; Matthai, F.; Mazzotta, P.; Melchiorri, A.; Mendes, L.; Mennella, A.; Migliaccio, M.; Mitra, S.; Miville-Deschenes, M.A.; Moneti, A.; Montier, L.; Morgante, G.; Mortlock, D.; Munshi, D.; Naselsky, P.; Nati, F.; Natoli, P.; Netterfield, C.B.; Norgaard-Nielsen, H.U.; Noviello, F.; Novikov, D.; Novikov, I.; Osborne, S.; Oxborrow, C.A.; Paci, F.; Pagano, L.; Pajot, F.; Paoletti, D.; Patanchon, G.; Perdereau, O.; Perotto, L.; Perrotta, F.; Piacentini, F.; Piat, M.; Pierpaoli, E.; Pietrobon, D.; Plaszczynski, S.; Pointecouteau, E.; Polenta, G.; Ponthieu, N.; Popa, L.; Poutanen, T.; Pratt, G.W.; Prezeau, G.; Prunet, S.; Puget, J.L.; Rachen, J.P.; Rebolo, R.; Reinecke, M.; Remazeilles, M.; Renault, C.; Ricciardi, S.; Riller, T.; Ristorcelli, I.; Rocha, G.; Rosset, C.; Roudier, G.; Rowan-Robinson, M.; Rusholme, B.; Sandri, M.; Santos, D.; Savini, G.; Scott, D.; Seiffert, M.D.; Serra, P.; Shellard, E.P.S.; Spencer, L.D.; Starck, J.L.; Stolyarov, V.; Stompor, R.; Sudiwala, R.; Sunyaev, R.; Sureau, F.; Sutton, D.; Suur-Uski, A.S.; Sygnet, J.F.; Tauber, J.A.; Tavagnacco, D.; Terenzi, L.; Toffolatti, L.; Tomasi, M.; Tristram, M.; Tucci, M.; Tuovinen, J.; Valenziano, L.; Valiviita, J.; Van Tent, B.; Vielva, P.; Villa, F.; Vittorio, N.; Wade, L.A.; Wandelt, B.D.; White, S.D.M.; Yvon, D.; Zacchei, A.; Zonca, A.

    2014-01-01

    The multi-frequency capability of the Planck satellite provides information both on the integrated history of star formation (via the cosmic infrared background, or CIB) and on the distribution of dark matter (via the lensing effect on the cosmic microwave background, or CMB). The conjunction of these two unique probes allows us to measure directly the connection between dark and luminous matter in the high redshift (1 1. We measure directly the SFR density with around 2 sigma significance for three redshift bins between z=1 and 7, thus opening a new window into the study of the formation of stars at early times.

  5. Material properties of various intraocular lenses in an experimental study.

    Science.gov (United States)

    Tehrani, Mana; Dick, H Burkhard; Wolters, Beate; Pakula, Tadeusz; Wolf, Evan

    2004-01-01

    With the recent introduction of small-incision cataract surgery, requirements for intraocular lens (IOL) flexibility, strength and hydrophilicity have rapidly evolved. The IOL surface, however, remains a critical factor influencing uveal biocompatibility. To objectively quantify factors of material properties of various IOLs using contact angle measurements, differential scanning calorimetry, dynamic-mechanical measurements and scanning electron microscopy. In our study, 17 currently available IOLs were investigated using contact angle measurements to assess hydrophilicity and biocompatibility, as well as differential scanning calorimetry for the estimation of glass transition temperature. Mechanical capacity and flexibility were investigated using dynamic-mechanical measurements. Additional analysis of the IOL surface was performed using scanning electron microscopy. The contact angle measurements of the studied IOLs revealed similar values within each group. The silicone IOLs had values between 106 and 119 degrees. The PMMA IOLs were found to have a narrower range of values, between 73.2 and 75.5 degrees. Lenses made of hydrogel had values between 59.2 and 69.1 degrees. The heparin-modified surface showed the lowest contact angle of 56.5 degrees. The glass transition temperature was determined by dynamic differential scanning calorimetry. The resulting values were between 118.8 and 113.5 degrees C for PMMA IOLs, 15.5 and 14.0 degrees C for acrylic IOLs, and -91.7 and -119.6 degrees C for silicone IOLs. The dynamic-mechanical measurements revealed that PMMA lenses manifested characteristics similar to glass, whereas silicone lenses had characteristics similar to rubber. Acrylic lenses were between rubber and glass. Scanning electron microscopy revealed smooth dispersion of fibrin on hydrophobic IOLs and a relative lack of fibrin adhesion on hydrophilic materials. These results demonstrate that material properties of various IOL materials are consistent within

  6. Optical loss due to diffraction by concentrator Fresnel lenses

    International Nuclear Information System (INIS)

    Hornung, Thorsten; Nitz, Peter

    2014-01-01

    Fresnel lenses are widely used in concentrating photovoltaic (CPV) systems as a primary optical element. They focus sunlight on small solar cells or on the entrance apertures of secondary optical elements. A Fresnel lens consists of several prism rings and diffraction by these prism rings is unavoidable. Some of the light that would reach a designated target area according to geometric optics will miss it due to diffraction. This diffraction loss may be of relevant magnitude for CPV applications. The results of published analytical calculations are evaluated, discussed, and compared to computer simulations and measurements

  7. Lenses on Reading An Introduction to Theories and Models

    CERN Document Server

    Tracey, Diane H

    2012-01-01

    This widely adopted text explores key theories and models that frame reading instruction and research. Readers learn why theory matters in designing and implementing high-quality instruction and research; how to critically evaluate the assumptions and beliefs that guide their own work; and what can be gained by looking at reading through multiple theoretical lenses. For each theoretical model, classroom applications are brought to life with engaging vignettes and teacher reflections. Research applications are discussed and illustrated with descriptions of exemplary studies. New to This Edition

  8. [Cataract extraction with intraocular lenses in a teaching hospital].

    Science.gov (United States)

    Jara, R; Charlín, R; Schweikart, A; Stoppel, J; Maul, E

    1991-07-01

    One hundred and twelve primary posterior chamber intraocular lens implants from a series of 560 eyes operated on at the Eye Service of Hospital Salvador in Santiago, Chile, were analyzed to determine the postoperative visual acuity. The follow up time varied between 3 and 26 months. Lenses were implanted by experienced ophthalmologists and residents in training. Visual acuity was 0.5 or better in 79.5% of cases. The postoperative visual acuity varied with age, being worse in patients over 70 years old.

  9. Three growing questions about Masonry

    Directory of Open Access Journals (Sweden)

    Davide Crimi

    2017-07-01

    Full Text Available Through three capital questions, this short essay tries to offer a general panorama and a better understanding of the proteiform complex body or Masonry. Through by a multi-level hermeneutic, this study get the ambition to be comprehensible both to Readers who are not used to this kind of literature and to the ones advanced and skilled in symbolic thought. The main important conclusion owes the quality of the symbolic level, which is the property to refuse a single interpretation: notwithstanding, this does not prevent from a clear historical and political evaluation of the phenomena under analysis, according the methodologies of social sciences. This political evaluability drives to the main valuable output of the essay, which concerns the anthropological statement that the logical label of Masonry, with this name or many others, it exists since always. Under the category of initiatory institution, we may consider the step between individual and society, and a society inside a larger one. Evolving from the needs of the individuals to the ones of social groups, the matter joins to the land of political sciences. The sociological meaning can be posed under analytic view in reason of the functionalist meaning emerging from the alternative couples status-quo/emancipation and conservatism/progressivism. Through by this perspective, anyway the theme seems not to reveal much more, because this “proteiform complex body” manifest itself as something too much complex in its inner core to be considered in a way or in another. What remains is strictly symbolic, with some theological and eschatological points that refuse to be posed under restrain.

  10. HPV Vaccine - Questions and Answers

    Science.gov (United States)

    ... Immunization Partners Sexually Transmitted Diseases HPV-Associated Cancers Gynecologic Cancers Questions and Answers Recommend on Facebook Tweet ... Immunization Partners Sexually Transmitted Diseases HPV-Associated Cancers Gynecologic Cancers File Formats Help: How do I view ...

  11. Question Inventory on Tobacco (QIT)

    Data.gov (United States)

    U.S. Department of Health & Human Services — 1965, 1966, 1970, 1974-2017. Centers for Disease Control and Prevention (CDC). Office on Smoking and Health (OSH). Tobacco-Related Survey Questions. The QIT is a...

  12. Climate Leadership Awards Frequent Questions

    Science.gov (United States)

    Provides answers to frequently asked questions regarding the Climate Leadership Awards, sponsored by EPA's Center for Corporate Climate Leadership with co-sponsorship from the Center for Climate and Energy Solutions and The Climate Registry.

  13. Frequently Asked Questions about Rotavirus

    Science.gov (United States)

    ... Herpes Zoster) Tetanus (Lockjaw) Frequently Asked Questions About Rotavirus What is Rotavirus? Why can dehydration be serious ... I find information about the vaccine? What is Rotavirus? Rotavirus is a highly contagious virus that infects ...

  14. LGBT Caregiving: Frequently Asked Questions

    Science.gov (United States)

    ... FCA - A A + A You are here Home LGBT Caregiving: Frequently Asked Questions Order this publication Printer- ... service or organization is open to working with LGBT families? Kudos to you for managing to “go ...

  15. Effect of patient wear and extent of protein deposition on adsorption of Acanthamoeba to five types of hydrogel contact lenses.

    Science.gov (United States)

    Simmons, P A; Tomlinson, A; Connor, R; Hay, J; Seal, D V

    1996-06-01

    Attachment of Acanthamoeba species to hydrogel contact lenses is a possible route of infection in Acanthamoeba keratitis. In this study, Acanthamoeba adsorption was compared with extent of lens deposition in worn lenses of different hydrogel polymers. After wear, lenses (80 lenses of 5 different types) were analyzed for total protein, surface area of deposition, and Acanthamoeba castellani trophozoite and cyst adsorption. Adsorption of Acanthamoeba trophozoites to worn lenses was greater than adsorption to unworn lenses for four of the five lens polymers (p 0.05). Adsorption was affected by both the water content and ionicity of the lens polymer. These results show that adsorption of Acanthamoeba to worn hydrogel contact lenses is greater than or equal to adsorption to unworn lenses.

  16. Comparison between Two Assessment Methods; Modified Essay Questions and Multiple Choice Questions

    Directory of Open Access Journals (Sweden)

    Assadi S.N.* MD

    2015-09-01

    Full Text Available Aims Using the best assessment methods is an important factor in educational development of health students. Modified essay questions and multiple choice questions are two prevalent methods of assessing the students. The aim of this study was to compare two methods of modified essay questions and multiple choice questions in occupational health engineering and work laws courses. Materials & Methods This semi-experimental study was performed during 2013 to 2014 on occupational health students of Mashhad University of Medical Sciences. The class of occupational health and work laws course in 2013 was considered as group A and the class of 2014 as group B. Each group had 50 students.The group A students were assessed by modified essay questions method and the group B by multiple choice questions method.Data were analyzed in SPSS 16 software by paired T test and odd’s ratio. Findings The mean grade of occupational health and work laws course was 18.68±0.91 in group A (modified essay questions and was 18.78±0.86 in group B (multiple choice questions which was not significantly different (t=-0.41; p=0.684. The mean grade of chemical chapter (p<0.001 in occupational health engineering and harmful work law (p<0.001 and other (p=0.015 chapters in work laws were significantly different between two groups. Conclusion Modified essay questions and multiple choice questions methods have nearly the same student assessing value for the occupational health engineering and work laws course.

  17. A gravitationally lensed quasar with quadruple images separated by 14.62 arcseconds.

    Science.gov (United States)

    Inada, Naohisa; Oguri, Masamune; Pindor, Bartosz; Hennawi, Joseph F; Chiu, Kuenley; Zheng, Wei; Ichikawa, Shin-Ichi; Gregg, Michael D; Becker, Robert H; Suto, Yasushi; Strauss, Michael A; Turner, Edwin L; Keeton, Charles R; Annis, James; Castander, Francisco J; Eisenstein, Daniel J; Frieman, Joshua A; Fukugita, Masataka; Gunn, James E; Johnston, David E; Kent, Stephen M; Nichol, Robert C; Richards, Gordon T; Rix, Hans-Walter; Sheldon, Erin Scott; Bahcall, Neta A; Brinkmann, J; Ivezić, Zeljko; Lamb, Don Q; McKay, Timothy A; Schneider, Donald P; York, Donald G

    2003-12-18

    Gravitational lensing is a powerful tool for the study of the distribution of dark matter in the Universe. The cold-dark-matter model of the formation of large-scale structures (that is, clusters of galaxies and even larger assemblies) predicts the existence of quasars gravitationally lensed by concentrations of dark matter so massive that the quasar images would be split by over 7 arcsec. Numerous searches for large-separation lensed quasars have, however, been unsuccessful. All of the roughly 70 lensed quasars known, including the first lensed quasar discovered, have smaller separations that can be explained in terms of galaxy-scale concentrations of baryonic matter. Although gravitationally lensed galaxies with large separations are known, quasars are more useful cosmological probes because of the simplicity of the resulting lens systems. Here we report the discovery of a lensed quasar, SDSS J1004 + 4112, which has a maximum separation between the components of 14.62 arcsec. Such a large separation means that the lensing object must be dominated by dark matter. Our results are fully consistent with theoretical expectations based on the cold-dark-matter model.

  18. Dioptrics of the facet lenses in the dorsal rim area of the cricket Gryllus bimaculatus

    NARCIS (Netherlands)

    Ukhanov, KY; Leertouwer, HL; Gribakin, FG; Stavenga, DG

    1996-01-01

    1. The optics of the corneal facet lenses from the dorsal rim area (DRA) and from the dorso-lateral areas (DA) of the compound eye of the cricket Gryllus bimaculatus were studied. 2. The DRA of the cricket eye contains quite normally shaped facet lenses. The diameter of the facet lens in the DA is

  19. The measurement of intraocular pressure over positive soft contact lenses by rebound tonometry

    Directory of Open Access Journals (Sweden)

    Fabrizio Zeri

    2016-07-01

    Conclusions: Rebound tonometry over positive hydrogel CLs leads to a certain degree of IOP underestimation. This result did not change for the two positive lenses used in the experiment, despite their large difference in power and therefore in lens thickness. Optometrists should bear this in mind when measuring IOP with the rebound tonometer over plus power contact lenses.

  20. Characterization of sand lenses and their role for subsurface transport in low-permeability clay tills

    DEFF Research Database (Denmark)

    Kessler, Timo Christian; Klint, K. E.; Nilsson, B.

    2011-01-01

    Glacial sediments dominate large parts of the geological topology in Denmark. They predominantly consist of lowpermeability tills, but fractures and sand-lenses constitute zones of enhanced permeability facilitating preferential flow. This study focuses on characterization of sand deposits with r...... the sand lenses in hydro-geological models to successfully characterize subsurface flow and transport, e.g. for remediation activities....

  1. Cosmetic Cleansing Oil Absorption by Soft Contact Lenses in Dry and Wet Conditions.

    Science.gov (United States)

    Tsukiyama, Junko; Miyamoto, Yuko; Kodama, Aya; Fukuda, Masahiko; Shimomura, Yoshikazu

    2017-09-01

    Previous reports showed that cosmetic cleansing oil for removing makeup, which contains mineral oil and surfactant, can deform some silicone hydrogel contact lenses (SHCLs) when applied directly to the lenses, although plasma-coated SHCLs (lotrafilcon A and B) were not affected. In the present study, we investigated hydrogel lenses and SHCLs in both wet and dry conditions. Several brands of hydrogel and SHCLs were immersed in a cleansing oil solution containing Sudan Black B for 5 min under wet and dry conditions. The lenses under the wet condition were simply picked up from the saline, whereas those under the dry condition were blotted with paper wipes. After immersing, the excess solution remaining on the lenses was removed by finger rubbing with a multipurpose solution. The lenses were then examined using a stereomicroscope, and their mean brightness was measured and compared. The cosmetic cleansing oil was not absorbed by the hydrogel lenses under wet or dry conditions. However, four of seven brands of SHCLs absorbed the cosmetic cleansing oil under both conditions (dry and wet), whereas asmofilcon A absorbed it only under the dry condition. Lotrafilcon B and delefilcon A did not absorb cleansing oil even under the dry condition. Hydrogel lenses resist cosmetic cleansing oil. However, SHCLs have different degrees of resistance depending on the lens material. Some SHCLs absorbed cosmetic cleansing oil more under dry conditions than under wet conditions.

  2. Planck 2013 results. XVII. Gravitational lensing by large-scale structure

    DEFF Research Database (Denmark)

    Ade, P. A. R.; Aghanim, N.; Armitage-Caplan, C.

    2013-01-01

    On the arcminute angular scales probed by Planck, the cosmic microwave background (CMB) anisotropies are gently perturbed by gravitational lensing. Here we present a detailed study of this eect, detecting lensing independently in the 100, 143, and 217 GHz frequency bands with an overall significa...

  3. Recovery of the water content of hydrogel contact lenses after use.

    Science.gov (United States)

    Cabrera, Josefa Velasco; Velasco, María José García

    2005-09-01

    The aim of the present study is to determine the amount and time of water-content recovery of ionic contact lenses (Surevue and Acuvue) and non-ionic contact lenses (Soflens 38, Soflens 66 and Optima 38) when submerged in maintenance solution for 9 h. Using a hand-held refractometer, we measured the water content of the lenses upon removal from the eye, and after 15, 30, 45 min, 1, 2 and 9 h in soaking solution. Both ionic lenses presented pre-wear water content of 58%, while two of the non-ionic ones (Soflens 38 and Optima 38) registered 38.6% and the third (Soflens 66) had 66%. We found a significant increase (p 0.05) between ionic and non-ionic lenses, although the non-ionic lenses reached slightly higher water-content values at all the times studied. These results indicate that when the refractometer technique is used to measure water content, the lens types used in this study regain their initial water-content values after 9 h in soaking solution. These data indicate the time needed for hydrogel contact lenses to reach their maximum water content after removal from the eye and submersion in maintenance solution. By ensuring maximum water content and minimum reduction of oxygen for the cornea, the specialist can help avoid clinical signs and symptoms related to low water content in the lenses.

  4. UVB-protective properties of contact lenses with intended use in photoresponsive eyelid dermatoses.

    Science.gov (United States)

    Depry, Jennifer; Golding, Robert; Szczotka-Flynn, Loretta; Dao, Harry; Baron, Elma; Cooper, Kevin

    2013-10-01

    UV-blocking contact lenses were evaluated to determine if they could provide adequate ocular protection during narrowband UVB phototherapy treatment. Theoretical safe exposure durations for the crystalline lens, cornea and conjunctiva were determined. A Cary 500 spectrophometer generated transmittance data for six UV-blocking and two non-UV-blocking contact lenses. An IL-1700 radiometer measured the lenses' radiation transmittance within the NB-UVB phototherapy unit. The lenses were exposed to a 1500-mJ/cm(2) dose of radiation from a 308-nm excimer laser to determine if the radiation would alter their protective properties. Theoretical safe exposure durations for eye structures were calculated using previous human and animal study data. All UV-blocking contact lenses showed less than 1E-7 W/cm(2) of radiation transmittance within the narrowband phototherapy unit. The excimer laser did not significantly alter the lenses' UV-blocking capabilities. The safe exposure durations for the cornea and crystalline lens were greater than 11 min with UV-blocking lenses, and that for the unprotected conjunctiva was approximately 11 s. Some UV-blocking contact lenses potentially provide sufficient ocular protection during narrowband UVB phototherapy treatment, as the crystalline lens and cornea are adequately protected should a patient open his or her eyes for a short time. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  5. Technology of Manufacture of the Negative Matrices for Linear Fresnel Lenses

    Science.gov (United States)

    Lapshin, V. V.; Zakharevich, E. M.; Grubyy, S. V.

    2016-04-01

    This article describes the main structural features of negative matrices which are intended for the production of positive copies of linear Fresnel lenses. Linear lenses are used in a space solar energy industry as solar concentrators in the photovoltaic modules. The article covers the essential requirements which are placed on the equipment and technology for the production of such matrices.

  6. Identification of Microorganisms Isolated From Counterfeit and Unapproved Decorative Contact Lenses.

    Science.gov (United States)

    Land, Adrian D; Penno, Katie L; Brzezinski, Jennifer L

    2018-03-01

    All contact lenses (corrective/noncorrective) are considered Class II or Class III medical devices under the Federal Food, Drug, and Cosmetic Act, which also states that contact lenses can only be obtained with a prescription. The Forensic Chemistry Center of the US Food & Drug Administration has examined over 300 decorative, noncorrective contact lenses obtained without a prescription. Our observations indicate that 60% of the counterfeit lenses and 27% of the unapproved lenses examined were positive for microbial contamination. Twenty-nine different brands of noncorrective contact lenses were examined, and 48% of them had at least one sample positive for microbial contamination. Each microorganism was further identified using DNA sequencing. Contaminated contact lenses are associated with numerous health risks, including ocular infections and conjunctivitis leading to permanent visual impairment or blindness. These results support the contention that acquiring contact lenses without a prescription is a considerable threat to consumer health and safety. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

  7. Adhesion of Pseudomonas aeruginosa to contact lenses after exposure to multi-purpose lens care solutions

    NARCIS (Netherlands)

    Bruinsma, GM; Van der Mei, HC; Busscher, HJ; de Vries, Jacob

    2001-01-01

    Elemental surface compositions of contact lenses were measured after exposure to different lens care solutions (LCS) using X-ray photoelectron spectroscopy and were related to adhesion and detachment of Pseudomonas aeruginosa. Etafilcon A and polymacon contact lenses, prior to and after exposure to

  8. Observations and analytical modeling of freshwater and rainwater lenses in coastal dune systems

    NARCIS (Netherlands)

    Stuijfzand, Pieter

    2016-01-01

    Observations are reported on (i) groundwater recharge rates under various types of vegetation as measured with megalysimeters in the dunes, (ii) freshwater lenses along the Dutch North Sea coast in the early 1900s, and (iii) rainwater lenses that develop on top of laterally migrating,

  9. Electromagnetic methods for mapping freshwater lenses on Micronesian atoll islands

    Science.gov (United States)

    Anthony, S.S.

    1992-01-01

    The overall shape of freshwater lenses can be determined by applying electromagnetic methods and inverse layered-earth modeling to the mapping of atoll island freshwater lenses. Conductivity profiles were run across the width of the inhabited islands at Mwoakilloa, Pingelap, and Sapwuahfik atolls of the Pohnpei State, Federated States of Micronesia using a dual-loop, frequency-domain, electromagnetic profiling system. Six values of apparent conductivity were recorded at each sounding station and were used to interpret layer conductivities and/or thicknesses. A three-layer model that includes the unsaturated, freshwater, and saltwater zones was used to simulate apparent-conductivity data measured in the field. Interpreted results were compared with chloride-concentration data from monitoring wells and indicate that the interface between freshwater and saltwater layers, defined from electromagnetic data, is located in the upper part of the transition zone, where the chloride-concentration profile shows a rapid increase with depth. The electromagnetic method can be used to interpret the thickness of the freshwater between monitoring wells, but can not be used to interpret the thickness of freshwater from monitoring wells to the margin of an island. ?? 1992.

  10. Constraining unified dark matter models with weak lensing

    Energy Technology Data Exchange (ETDEWEB)

    Camera, S. [Dipartimento di Fisica Generale Amedeo Avogadro, Universita degli Studi di Torino, Torino (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Torino, Torino (Italy)

    2010-04-15

    Unified Dark Matter (UDM) models provide an intriguing alternative to Dark Matter (DM) and Dark Energy (DE) through only one exotic component, i.e. a classical scalar field {phi}(t,x). Thanks to a non-canonical kinetic term, this scalar field can mimic both the behaviour of the matter-dominated era at earlier times, as DM do, and the outcoming late-time acceleration, as a cosmological constant DE. Thus, it has been shown that these models can reproduce the same expansion history of the {lambda}CDM concordance model. In this work I review the first prediction of a physical observable, the power spectrum of the weak lensing cosmic convergence (shear). I present the weak lensing signal as predicted by the standard {lambda}CDM model and by a family of viable UDM models parameterized by the late-time sound speed c{sub {infinity}} of the scalar field.last-scattering surface and a series of background galaxies peaked at different redshifts and spread over different redshifts as described by a functional form of their distribution of sources. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  11. Cusp-core problem and strong gravitational lensing

    International Nuclear Information System (INIS)

    Li Nan; Chen Daming

    2009-01-01

    Cosmological numerical simulations of galaxy formation have led to the cuspy density profile of a pure cold dark matter halo toward the center, which is in sharp contradiction with the observations of the rotation curves of cold dark matter-dominated dwarf and low surface brightness disk galaxies, with the latter tending to favor mass profiles with a flat central core. Many efforts have been devoted to resolving this cusp-core problem in recent years, among them, baryon-cold dark matter interactions are considered to be the main physical mechanisms erasing the cold dark matter (CDM) cusp into a flat core in the centers of all CDM halos. Clearly, baryon-cold dark matter interactions are not customized only for CDM-dominated disk galaxies, but for all types, including giant ellipticals. We first fit the most recent high resolution observations of rotation curves with the Burkert profile, then use the constrained core size-halo mass relation to calculate the lensing frequency, and compare the predicted results with strong lensing observations. Unfortunately, it turns out that the core size constrained from rotation curves of disk galaxies cannot be extrapolated to giant ellipticals. We conclude that, in the standard cosmological paradigm, baryon-cold dark matter interactions are not universal mechanisms for galaxy formation, and therefore, they cannot be true solutions to the cusp-core problem.

  12. The Weak Lensing Masses of Filaments between Luminous Red Galaxies

    Science.gov (United States)

    Epps, Seth D.; Hudson, Michael J.

    2017-07-01

    In the standard model of non-linear structure formation, a cosmic web of dark-matter-dominated filaments connects dark matter haloes. In this paper, we stack the weak lensing signal of an ensemble of filaments between groups and clusters of galaxies. Specifically, we detect the weak lensing signal, using CFHTLenS galaxy ellipticities, from stacked filaments between Sloan Digital Sky Survey (SDSS)-III/Baryon Oscillation Spectroscopic Survey luminous red galaxies (LRGs). As a control, we compare the physical LRG pairs with projected LRG pairs that are more widely separated in redshift space. We detect the excess filament mass density in the projected pairs at the 5σ level, finding a mass of (1.6 ± 0.3) × 1013 M⊙ for a stacked filament region 7.1 h-1 Mpc long and 2.5 h-1 Mpc wide. This filament signal is compared with a model based on the three-point galaxy-galaxy-convergence correlation function, as developed in Clampitt et al., yielding reasonable agreement.

  13. Low-energy beam transport using space-charge lenses

    International Nuclear Information System (INIS)

    Meusel, O.; Bechtold, A.; Pozimski, J.; Ratzinger, U.; Schempp, A.; Klein, H.

    2005-01-01

    Space-charge lenses (SCL) of the Gabor type provide strong cylinder symmetric focusing for low-energy ion beams using a confined nonneutral plasma. They need modest magnetic and electrostatic field strength and provide a short installation length when compared to conventional LEBT-lenses like quadrupoles and magnetic solenoids. The density distribution of the enclosed space charge within the Gabor lens is given by the confinement in transverse and longitudinal directions. In the case of a positive ion beam, the space charge of the confined electron cloud may cause an overcompensation of the ion beam space-charge force and consequently focuses the beam. To investigate the capabilities of an SCL double-lens system for ion beam into an RFQ, a test injector was installed at IAP and put into operation successfully. Furthermore, to study the focusing capabilities of this lens at beam energies up to 500 keV, a high-field Gabor lens was built and installed downstream of the RFQ. Experimental results of the beam injection into the RFQ are presented as well as those of these first bunched beam-focusing tests with the 110 A keV He + beam

  14. Simulation-based marginal likelihood for cluster strong lensing cosmology

    Science.gov (United States)

    Killedar, M.; Borgani, S.; Fabjan, D.; Dolag, K.; Granato, G.; Meneghetti, M.; Planelles, S.; Ragone-Figueroa, C.

    2018-01-01

    Comparisons between observed and predicted strong lensing properties of galaxy clusters have been routinely used to claim either tension or consistency with Λ cold dark matter cosmology. However, standard approaches to such cosmological tests are unable to quantify the preference for one cosmology over another. We advocate approximating the relevant Bayes factor using a marginal likelihood that is based on the following summary statistic: the posterior probability distribution function for the parameters of the scaling relation between Einstein radii and cluster mass, α and β. We demonstrate, for the first time, a method of estimating the marginal likelihood using the X-ray selected z > 0.5 Massive Cluster Survey clusters as a case in point and employing both N-body and hydrodynamic simulations of clusters. We investigate the uncertainty in this estimate and consequential ability to compare competing cosmologies, which arises from incomplete descriptions of baryonic processes, discrepancies in cluster selection criteria, redshift distribution and dynamical state. The relation between triaxial cluster masses at various overdensities provides a promising alternative to the strong lensing test.

  15. Probing the cosmic distance duality relation using time delay lenses

    Energy Technology Data Exchange (ETDEWEB)

    Rana, Akshay; Mahajan, Shobhit; Mukherjee, Amitabha [Department of Physics and Astrophysics, University of Delhi, Delhi 110007 (India); Jain, Deepak [Deen Dayal Upadhyaya College, University of Delhi, Sector-3, Dwarka, New Delhi 110078 (India); Holanda, R.F.L., E-mail: montirana1992@gmail.com, E-mail: djain@ddu.du.ac.in, E-mail: shobhit.mahajan@gmail.com, E-mail: amimukh@gmail.com, E-mail: holanda@uepb.edu.br [Departamento de Física, Universidade Federal de Sergipe, 49100-000, Aracaju—SE (Brazil)

    2017-07-01

    The construction of the cosmic distance-duality relation (CDDR) has been widely studied. However, its consistency with various new observables remains a topic of interest. We present a new way to constrain the CDDR η( z ) using different dynamic and geometric properties of strong gravitational lenses (SGL) along with SNe Ia observations. We use a sample of 102 SGL with the measurement of corresponding velocity dispersion σ{sub 0} and Einstein radius θ {sub E} . In addition, we also use a dataset of 12 two image lensing systems containing the measure of time delay Δ t between source images. Jointly these two datasets give us the angular diameter distance D {sub A} {sub ol} of the lens. Further, for luminosity distance, we use the 740 observations from JLA compilation of SNe Ia. To study the combined behavior of these datasets we use a model independent method, Gaussian Process (GP). We also check the efficiency of GP by applying it on simulated datasets, which are generated in a phenomenological way by using realistic cosmological error bars. Finally, we conclude that the combined bounds from the SGL and SNe Ia observation do not favor any deviation of CDDR and are in concordance with the standard value (η=1) within 2σ confidence region, which further strengthens the theoretical acceptance of CDDR.

  16. Polymer-interaction driven diffusionof eyeshadow in soft contact lenses.

    Science.gov (United States)

    Tavazzi, Silvia; Rossi, Alessandra; Picarazzi, Sara; Ascagni, Miriam; Farris, Stefano; Borghesi, Alessandro

    2017-10-01

    Soft contact lenses used for the correction of ametropia are often made of hydrogel and silicone-hydrogel materials. Since they are placed directly on the surface of the eye and they are hydrated by tears, eye cosmetics can compromise the lens performance and, even worse, can be transported from an external environment to the ocular surface through the contact lens. The diffusion of the dye component of a purple eyeshadow in soft contact lenses of different materials is here evaluated. Diffusivity is found to be typically higher in silicone-hydrogels than in hydrogels. In hydrogels, diffusivity is greater in the case of lower oxygen transmissibility. Despite differences between materials, absorbed mass of dye is much larger (10-100 times) than the expected mass by simple hydration and swelling of the contact lens. The most contaminated materials are also resistant to cleaning solutions. The results indicate that, notwithstanding the complexity of contact lens networks, diffusion of dye is found to follow Fick's law and it is driven by polymer-dye interaction, which governs lens hydration and swelling. Copyright © 2017 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  17. An Electrically Tunable Zoom System Using Liquid Lenses.

    Science.gov (United States)

    Li, Heng; Cheng, Xuemin; Hao, Qun

    2015-12-31

    A four-group stabilized zoom system using two liquid lenses and two fixed lens groups is proposed. We describe the design principle, realization, and the testing of a 5.06:1 zoom system. The realized effective focal length (EFL) range is 6.93 mm to 35.06 mm, and the field of view (FOV) range is 8° to 40°. The system can zoom fast when liquid lens 1's (L₁'s) optical power take the value from 0.0087 mm(-1) to 0.0192 mm(-1) and liquid lens 2's (L₂'s) optical power take the value from 0.0185 mm(-1) to -0.01 mm(-1). Response time of the realized zoom system was less than 2.5 ms, and the settling time was less than 15 ms.The analysis of elements' parameters and the measurement of lens performance not only verify the design principle further, but also show the zooming process by the use of two liquid lenses. The system is useful for motion carriers e.g., robot, ground vehicle, and unmanned aerial vehicles considering that it is fast, reliable, and miniature.

  18. Weak Lensing by Galaxy Clusters: from Pixels to Cosmology

    International Nuclear Information System (INIS)

    Gruen, Daniel

    2015-01-01

    The story of the origin and evolution of our Universe is told, equivalently, by space-time itself and by the structures that grow inside of it. Clusters of galaxies are the frontier of bottom-up structure formation. They are the most massive objects to have collapsed at the present epoch. By that virtue, their abundance and structural parameters are highly sensitive to the composition and evolution of the Universe. The most common probe of cluster cosmology, abundance, uses samples of clusters selected by some observable. Applying a mass-observable relation (MOR), cosmological parameters can be constrained by comparing the sample to predicted cluster abundances as a function of observable and redshift. Arguably, however, cluster probes have not yet entered the era of per cent level precision cosmology. The primary reason for this is our imperfect understanding of the MORs. The overall normalization, the slope of mass vs. observable, the redshift evolution, and the degree and correlation of intrinsic scatters of observables at fixed mass have to be constrained for interpreting abundances correctly. Mass measurement of clusters by means of the differential deflection of light from background sources in their gravitational field, i.e. weak lensing, is a powerful approach for achieving this. This thesis presents new methods for and scientific results of weak lensing measurements of clusters of galaxies. The former include, on the data reduction side, (i) the correction of CCD images for non-linear effects due to the electric fields of accumulated charges and (ii) a method for masking artifact features in sets of overlapping images of the sky by comparison to the median image. Also, (iii) I develop a method for the selection of background galaxy samples based on their color and apparent magnitude that includes a new correction for contamination with cluster member galaxies. The main scientific results are the following. (i) For the Hubble Frontier Field cluster RXC J

  19. Weak Lensing by Galaxy Clusters: from Pixels to Cosmology

    Energy Technology Data Exchange (ETDEWEB)

    Gruen, Daniel [Ludwig Maximilian Univ., Munich (Germany)

    2015-03-11

    The story of the origin and evolution of our Universe is told, equivalently, by space-time itself and by the structures that grow inside of it. Clusters of galaxies are the frontier of bottom-up structure formation. They are the most massive objects to have collapsed at the present epoch. By that virtue, their abundance and structural parameters are highly sensitive to the composition and evolution of the Universe. The most common probe of cluster cosmology, abundance, uses samples of clusters selected by some observable. Applying a mass-observable relation (MOR), cosmological parameters can be constrained by comparing the sample to predicted cluster abundances as a function of observable and redshift. Arguably, however, cluster probes have not yet entered the era of per cent level precision cosmology. The primary reason for this is our imperfect understanding of the MORs. The overall normalization, the slope of mass vs. observable, the redshift evolution, and the degree and correlation of intrinsic scatters of observables at fixed mass have to be constrained for interpreting abundances correctly. Mass measurement of clusters by means of the differential deflection of light from background sources in their gravitational field, i.e. weak lensing, is a powerful approach for achieving this. This thesis presents new methods for and scientific results of weak lensing measurements of clusters of galaxies. The former include, on the data reduction side, (i) the correction of CCD images for non-linear effects due to the electric fields of accumulated charges and (ii) a method for masking artifact features in sets of overlapping images of the sky by comparison to the median image. Also, (iii) I develop a method for the selection of background galaxy samples based on their color and apparent magnitude that includes a new correction for contamination with cluster member galaxies. The main scientific results are the following. (i) For the Hubble Frontier Field cluster RXC J

  20. Optical quality and vision with iris-coloring soft contact lenses.

    Science.gov (United States)

    Ortiz, Carolina; Jiménez, Raimundo

    2014-05-01

    To study the influence of iris-coloring soft contact lenses, designed for changing apparent iris color, on optical quality and vision. Eighty subjects were included in this study. All participants were classified as emmetropic, with monocular best-corrected visual acuity of 20/20 or better. For 40 subjects, we measured the optical quality (aberrations, the Strehl ratio, and the objective scattering index) and visual performance before and after wearing the cosmetic soft contact lenses. We also measured the optical quality and visual performance for the other 40 subjects but with a different kind of lens (fantasy soft contact lenses). Iris-coloring soft contact lenses significantly increased coma-like and total higher-order aberrations and objective scattering index (p Iris-coloring soft contact lenses deteriorate the optical quality and worsen the contrast sensitivity function. Iris-coloring soft contact lens wearers should be informed about the effects on optical quality and visual function.