WorldWideScience

Sample records for lensing potential fluctuations

  1. 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.

  2. Small-scale fluctuations in the microwave background radiation and multiple gravitational lensing

    International Nuclear Information System (INIS)

    Kashlinsky, A.

    1988-01-01

    It is shown that multiple gravitational lensing of the microwave background radiation (MBR) by static compact objects significantly attenuates small-scale fluctuations in the MBR. Gravitational lensing, by altering trajectories of MBR photons reaching an observer, leads to (phase) mixing of photons from regions with different initial fluctuations. As a result of this diffusion process the original fluctuations are damped on scales up to several arcmin. An equation that describes this process and its general solution are given. It is concluded that the present upper limits on the amplitude of the MBR fluctuations on small scales cannot constrain theories of galaxy formation. 25 references

  3. Constraints on small-scale cosmological fluctuations from SNe lensing dispersion

    International Nuclear Information System (INIS)

    Ben-Dayan, Ido; Takahashi, Ryuichi

    2015-04-01

    We provide predictions on small-scale cosmological density power spectrum from supernova lensing dispersion. Parameterizing the primordial power spectrum with running α and running of running β of the spectral index, we exclude large positive α and β parameters which induce too large lensing dispersions over current observational upper bound. We ran cosmological N-body simulations of collisionless dark matter particles to investigate non-linear evolution of the primordial power spectrum with positive running parameters. The initial small-scale enhancement of the power spectrum is largely erased when entering into the non-linear regime. For example, even if the linear power spectrum at k>10 hMpc -1 is enhanced by 1-2 orders of magnitude, the enhancement much decreases to a factor of 2-3 at late time (z≤1.5). Therefore, the lensing dispersion induced by the dark matter fluctuations weakly constrains the running parameters. When including baryon-cooling effects (which strongly enhance the small-scale clustering), the constraint is comparable or tighter than the PLANCK constraint, depending on the UV cut-off. Further investigations of the non-linear matter spectrum with baryonic processes is needed to reach a firm constraint.

  4. Quantum tunnelling fluctuations in anharmonic potentials

    International Nuclear Information System (INIS)

    Papadopoulos, G.J.; Hadjiagapiou, I.A.

    1993-01-01

    A nonlinear perturbation theory is developed for the logarithm of the wavefunction. It is then used developing a long range time perturbation series for the wavefunction of the Schroedinger equation in the case of a cubic potential exhibiting a valley and a hump. Starting with a low energy Gaussian wavefunction centred at the bottom of the valley the profiles of the probability and current densities are obtained at different times, thus providing an idea of their evolution. While the probability density is slightly displaced the current density, starting from zero, fluctuates vividly. (author). 4 refs, 4 figs

  5. 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.

  6. Nonstandard primordial fluctuations from a polynomial inflation potential

    International Nuclear Information System (INIS)

    Hodges, H.M.; Kofman, L.A.; Primack, J.R.; California Univ., Santa Cruz, CA; California Univ., Berkeley, CA

    1990-01-01

    We examine in detail the properties of inflation determined from the most general renormalizable potential for a single real scalar field Φ: V(Φ)=AΦ 4 /4+BΦ 3 /3+CΦ 2 /2+V 0 . We find sets of parameters that can strongly break scale invariance, with a valley in the usual Zel'dovich spectrum. Such a valley can lead to earlier galaxy formation and more large scale structure in the Universe than in the usual scale-invariant cold dark matter scenario. We also find that the parameters of the potential can be many orders of magnitude larger than what would be allowed without the inclusion of the cubic term, which can lead to high reheat temperatures T reh ≅ 10 15 GeV. We have mapped out all regions of parameter space and have identified those regions that produce interesting behavior, as well as the entire region that leads to an acceptable inflationary scenario with small enough fluctuations. We further explore the possibility of generating interesting non-gaussian adiabatic density fluctuations from this potential, and find that it is unlikely for general single scalar field potentials that do not contain false vacua in the path of the inflaton, as significant non-gaussian behavior implies too large a fluctuation amplitude. (orig.)

  7. Stable isotopes in fish eye lenses as potential recorders of trophic and geographic history.

    Science.gov (United States)

    Wallace, Amy A; Hollander, David J; Peebles, Ernst B

    2014-01-01

    We evaluated eye lenses as potential recorders of stable isotope histories in fish because they consist of metabolically inert optical proteins that are deposited in successive, concentric circles (laminae) much like otolith circuli and tree rings. We conducted four different tests on lenses from red snapper, red grouper, gag, and white grunt. The first test was a low-resolution screening of multiple individuals (4-5 radial groups of laminae per lens, all species except white grunt). Along the radial axis, all individuals exhibited substantial isotopic variability. Red snapper individuals separated into two groups based on δ15N and gag separated into two groups based on δ13C. Two gag with the greatest variation were chosen for high-resolution temporal analysis using individual laminae from their second eye lenses. The first-order patterns from the high-resolution analysis generally mimicked patterns from the low-resolution screening of grouped laminae, yet the high-resolution plots revealed early-life details that were not apparent in the low-resolution screenings. For the third test, left- versus right-eye variation was compared using high-resolution methods. White grunt left- and right-eye radial isotopic patterns were almost identical for both δ13C and δ15N, suggesting the variations observed among individual fish were not artifacts. The final test evaluated intra-laminar variation; multiple samples were analyzed from different parts of the same lamina. Seven laminae from three individuals of two species were analyzed in this manner; variations among laminae were found to be much higher than variations within laminae. However, nominal intra-laminar variations were comparable to nominal differences between left and right lenses, suggesting intra-laminar variation established measurement precision. Eye lens isotopes appear to be useful for reconstructing the isotopic histories of individual fish; these histories can be compared with spatially-derived isoscapes

  8. Stable isotopes in fish eye lenses as potential recorders of trophic and geographic history.

    Directory of Open Access Journals (Sweden)

    Amy A Wallace

    Full Text Available We evaluated eye lenses as potential recorders of stable isotope histories in fish because they consist of metabolically inert optical proteins that are deposited in successive, concentric circles (laminae much like otolith circuli and tree rings. We conducted four different tests on lenses from red snapper, red grouper, gag, and white grunt. The first test was a low-resolution screening of multiple individuals (4-5 radial groups of laminae per lens, all species except white grunt. Along the radial axis, all individuals exhibited substantial isotopic variability. Red snapper individuals separated into two groups based on δ15N and gag separated into two groups based on δ13C. Two gag with the greatest variation were chosen for high-resolution temporal analysis using individual laminae from their second eye lenses. The first-order patterns from the high-resolution analysis generally mimicked patterns from the low-resolution screening of grouped laminae, yet the high-resolution plots revealed early-life details that were not apparent in the low-resolution screenings. For the third test, left- versus right-eye variation was compared using high-resolution methods. White grunt left- and right-eye radial isotopic patterns were almost identical for both δ13C and δ15N, suggesting the variations observed among individual fish were not artifacts. The final test evaluated intra-laminar variation; multiple samples were analyzed from different parts of the same lamina. Seven laminae from three individuals of two species were analyzed in this manner; variations among laminae were found to be much higher than variations within laminae. However, nominal intra-laminar variations were comparable to nominal differences between left and right lenses, suggesting intra-laminar variation established measurement precision. Eye lens isotopes appear to be useful for reconstructing the isotopic histories of individual fish; these histories can be compared with spatially

  9. 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.

  10. 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

  11. A MEASUREMENT OF THE COSMIC MICROWAVE BACKGROUND GRAVITATIONAL LENSING POTENTIAL FROM 100 SQUARE DEGREES OF SPTPOL DATA

    Energy Technology Data Exchange (ETDEWEB)

    Story, K. T.; Hanson, D.; Ade, P. A. R.; Aird, K. A.; Austermann, J. E.; J. A. Beall,; Bender, A. N.; Benson, B. A.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Chiang, H. C.; Cho, H-M.; Citron, R.; Crawford, T. M.; Crites, A. T.; Haan, T. de; Dobbs, M. A.; Everett, W.; Gallicchio, J.; Gao, J.; George, E. M.; Gilbert, A.; Halverson, N. W.; Harrington, N.; Henning, J. W.; Hilton, G. C.; Holder, G. P.; Holzapfel, W. L.; Hoover, S.; Hou, Z.; Hrubes, J. D.; Huang, N.; Hubmayr, J.; Irwin, K. D.; Keisler, R.; Knox, L.; Lee, A. T.; Leitch, E. M.; Li, D.; Liang, C.; Luong-Van, D.; McMahon, J. J.; Mehl, J.; Meyer, S. S.; Mocanu, L.; Montroy, T. E.; Natoli, T.; Nibarger, J. P.; Novosad, V.; Padin, S.; Pryke, C.; Reichardt, C. L.; Ruhl, J. E.; Saliwanchik, B. R.; Sayre, J. T.; Schaffer, K. K.; Smecher, G.; Stark, A. A.; Tucker, C.; Vanderlinde, K.; Vieira, J. D.; Wang, G.; Whitehorn, N.; Yefremenko, V.; Zahn, O.

    2015-08-28

    We present a measurement of the cosmic microwave background (CMB) gravitational lensing potential using data from the first two seasons of observations with SPTpol, the polarization-sensitive receiver currently installed on the South Pole Telescope. The observations used in this work cover 100 deg(2) of sky with arcminute resolution at 150 GHz. Using a quadratic estimator, we make maps of the CMB lensing potential from combinations of CMB temperature and polarization maps. We combine these lensing potential maps to form a minimum-variance (MV) map. The lensing potential is measured with a signal-to-noise ratio of greater than one for angular multipoles between $100\\lt L\\lt 250$. This is the highest signal-to-noise mass map made from the CMB to date and will be powerful in cross-correlation with other tracers of large-scale structure. We calculate the power spectrum of the lensing potential for each estimator, and we report the value of the MV power spectrum between $100\\lt L\\lt 2000$ as our primary result. We constrain the ratio of the spectrum to a fiducial ΛCDM model to be A(MV) = 0.92 ± 0.14 (Stat.) ± 0.08 (Sys.). Restricting ourselves to polarized data only, we find A(POL) = 0.92 ± 0.24 (Stat.) ± 0.11 (Sys.). This measurement rejects the hypothesis of no lensing at $5.9\\sigma $ using polarization data alone, and at $14\\sigma $ using both temperature and polarization data.

  12. Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential

    DEFF Research Database (Denmark)

    Loubet, Bastien; Lomholt, Michael Andersen; Khandelia, Himanshu

    2013-01-01

    We investigate the effect of an applied electric potential on the mechanics of a coarse grained POPC bilayer under tension. The size and duration of our simulations allow for a detailed and accurate study of the fluctuations. Effects on the fluctuation spectrum, tension, bending rigidity......, and bilayer thickness are investigated in detail. In particular, the least square fitting technique is used to calculate the fluctuation spectra. The simulations confirm a recently proposed theory that the effect of an applied electric potential on the membrane will be moderated by the elastic properties...... of the membrane. In agreement with the theory, we find that the larger the initial tension the larger the effect of the electric potential. Application of the electric potential increases the amplitude of the long wavelength part of the spectrum and the bending rigidity is deduced from the short wavelength...

  13. Tension moderation and fluctuation spectrum in simulated lipid membranes under an applied electric potential.

    Science.gov (United States)

    Loubet, Bastien; Lomholt, Michael Andersen; Khandelia, Himanshu

    2013-10-28

    We investigate the effect of an applied electric potential on the mechanics of a coarse grained POPC bilayer under tension. The size and duration of our simulations allow for a detailed and accurate study of the fluctuations. Effects on the fluctuation spectrum, tension, bending rigidity, and bilayer thickness are investigated in detail. In particular, the least square fitting technique is used to calculate the fluctuation spectra. The simulations confirm a recently proposed theory that the effect of an applied electric potential on the membrane will be moderated by the elastic properties of the membrane. In agreement with the theory, we find that the larger the initial tension the larger the effect of the electric potential. Application of the electric potential increases the amplitude of the long wavelength part of the spectrum and the bending rigidity is deduced from the short wavelength fluctuations. The effect of the applied electric potential on the bending rigidity is non-existent within error bars. However, when the membrane is stretched there is a point where the bending rigidity is lowered due to a decrease of the thickness of the membrane. All these effects should prove important for mechanosensitive channels and biomembrane mechanics in general.

  14. Charging a Capacitor from an External Fluctuating Potential using a Single Conical Nanopore

    Science.gov (United States)

    Gomez, Vicente; Ramirez, Patricio; Cervera, Javier; Nasir, Saima; Ali, Mubarak; Ensinger, Wolfgang; Mafe, Salvador

    2015-01-01

    We explore the electrical rectification of large amplitude fluctuating signals by an asymmetric nanostructure operating in aqueous solution. We show experimentally and theoretically that a load capacitor can be charged to voltages close to 1 V within a few minutes by converting zero time-average potentials of amplitudes in the range 0.5–3 V into average net currents using a single conical nanopore. This process suggests that significant energy conversion and storage from an electrically fluctuating environment is feasible with a nanoscale pore immersed in a liquid electrolyte solution, a system characteristic of bioelectronics interfaces, electrochemical cells, and nanoporous membranes. PMID:25830563

  15. Charging a capacitor from an external fluctuating potential using a single conical nanopore.

    Science.gov (United States)

    Gomez, Vicente; Ramirez, Patricio; Cervera, Javier; Nasir, Saima; Ali, Mubarak; Ensinger, Wolfgang; Mafe, Salvador

    2015-04-01

    We explore the electrical rectification of large amplitude fluctuating signals by an asymmetric nanostructure operating in aqueous solution. We show experimentally and theoretically that a load capacitor can be charged to voltages close to 1 V within a few minutes by converting zero time-average potentials of amplitudes in the range 0.5-3 V into average net currents using a single conical nanopore. This process suggests that significant energy conversion and storage from an electrically fluctuating environment is feasible with a nanoscale pore immersed in a liquid electrolyte solution, a system characteristic of bioelectronics interfaces, electrochemical cells, and nanoporous membranes.

  16. Exchange symmetry, fluctuation-compressibility relation, and thermodynamic potentials of quantum liquids.

    Science.gov (United States)

    Lim, Yu Rim; Park, Seong Jun; Song, Sanggeun; Yang, Gil-Suk; Yoon, Young-Gui; Kim, Ji-Hyun; Sung, Jaeyoung

    2014-06-01

    Liquid helium does not obey the Gibbs fluctuation-compressibility relation, which was noted more than six decades ago. However, still missing is a clear explanation of the reason for the deviation or the correct fluctuation-compressibility relation for the quantum liquid. Here we present the fluctuation-compressibility relation valid for any grand canonical system. Our result shows that the deviation from the Gibbs formula arises from a nonextensive part of thermodynamic potentials. The particle-exchange symmetry of many-body wave function of a strongly degenerate quantum gas is related to the thermodynamic extensivity of the system; a Bose gas does not always obey the Gibbs formula, while a Fermi gas does. Our fluctuation-compressibility relation works for classical systems as well as quantum systems. This work demonstrates that the application range of the Gibbs-Boltzmann statistical thermodynamics can be extended to encompass nonextensive open systems without introducing any postulate other than the principle of equal a priori probability.

  17. 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.

  18. Nematic fluctuations, fermiology and the pairing potential in iron-based superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kretzschmar, Florian

    2015-08-18

    The thesis comprises a systematic study on the doping, temperature and momentum dependent electron dynamics in iron-based superconductors using inelastic light scattering. The observation of Bardasis-Schrieffer modes in the excitation spectrum of superconducting Ba{sub 0.6}K{sub 0.4}Fe{sub 2}As{sub 2} is reported and the energy and symmetry dependence of the modes are analyzed. The analysis yields the identification of a strong subdominant component of the interaction potential V(k,k{sup '}). Strong nematic fluctuations are investigated in Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2}. The nature of the fluctuations and the origin of nematicity in Ba(Fe{sub 1-x}Co{sub x}){sub 2}As{sub 2} are identified.

  19. 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.

  20. Asymptotic behavior of correlation functions for electric potential and field fluctuations in a classical one-component plasma

    NARCIS (Netherlands)

    Suttorp, L.G.

    1992-01-01

    The correlations of the electric potential fluctuations in a classical one-component plasma are studied for large distances between the observation points. The two-point correlation function for these fluctuations is known to decay slowly for large distances, even if exponential clustering holds for

  1. Spectroscopic imaging of photopotentials and photoinduced potential fluctuations in a bulk heterojunction solar cell film.

    Science.gov (United States)

    Luria, Justin L; Hoepker, Nikolas; Bruce, Robert; Jacobs, Andrew R; Groves, Chris; Marohn, John A

    2012-11-27

    We present spatially resolved photovoltage spectra of a bulk heterojunction solar cell film composed of phase-separated poly(9,9'-dioctylfluorene-co-benzothiadiazole) (F8BT) and poly(9,9'-dioctylfluorene-co-bis-N,N'-(4-butylphenyl)-bis-N,N'-phenyl-1,4-phenylenediamine) (PFB) polymers prepared on ITO/PEDOT:PSS and aluminum substrates. Over both PFB- and F8BT-rich domains, the photopotential spectra were found to be proportional to a linear combination of the polymers' absorption spectra. Charge trapping in the film was studied using photopotential fluctuation spectroscopy, in which low-frequency photoinduced electrostatic potential fluctuations were measured by observing noise in the oscillation frequency of a nearby charged atomic force microscope cantilever. Over both F8BT- and PFB-rich regions, the magnitude, distance dependence, frequency dependence, and illumination wavelength dependence of the observed cantilever frequency noise are consistent with photopotential fluctuations arising from stochastic light-driven trapping and detrapping of charges in F8BT. Taken together, our findings suggest a microscopic mechanism by which intermixing of phases leads to charge trapping and thereby to suppressed open-circuit voltage and decreased efficiency in this prototypical bulk heterojunction solar cell film.

  2. 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

  3. Role of potential fluctuations in phase-change GST memory devices

    Energy Technology Data Exchange (ETDEWEB)

    Agarwal, Satish C. [Department of Physics, Indian Institute of Technology, Kanpur 208016 (India)

    2012-10-15

    The long range potential fluctuations (LRPFs) arising from the defects and heterogeneities in disordered semiconductors are important for understanding their atomic and electronic properties. Here, they are measured in Ge{sub X}Sb{sub Y}Te{sub 1-X-Y} (GST) chalcogenide glasses used in rewritable phase change memory (PCM) devices. It is found that the most commonly used composition Ge{sub 2}Sb{sub 2}Te{sub 5} has the smallest LRPF amongst its nearby compositions. This finding may be useful in the search for better PCM materials. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. A study of passivation/depassivation of carbon steel; electrochemical impedance spectrocopy vs. potential noise fluctuations

    International Nuclear Information System (INIS)

    Roberge, P.R.; Halliop, E.; Sastri, V.S.

    1992-01-01

    A technique based on recording corrosion potential fluctuations generated by corroding electrodes was used under open-circuit conditions to study passivation and depassivation of carbon steel. Quantification of the electrochemical signal in terms of the pitting corrosion rate has been attempted. The amplitude of electrochemical noise signals was analyzed under different pitting conditions and correlated to polarization resistance values obtained from the electrochemical impedance spectra. The automatic statistical data analysis of electrochemical impedance data points has been successfully applied to calculate polarization resistance values and other interesting characteristics of such measurements

  5. Lensing-induced morphology changes in CMB temperature maps in modified gravity theories

    Energy Technology Data Exchange (ETDEWEB)

    Munshi, D.; Coles, P. [Astronomy Centre, School of Mathematical and Physical Sciences, University of Sussex, Brighton BN1 9QH (United Kingdom); Hu, B. [Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona (IEEC-UB), Martí i Franquès 1, E08028 Barcelona (Spain); Matsubara, T. [Kobayashi-Maskawa Institute, Nagoya University, Chikusa, Nagoya 464-8602 (Japan); Heavens, A., E-mail: D.Munshi@sussex.ac.uk, E-mail: binhu@icc.ub.edu, E-mail: taka@kmi.nagoya-u.ac.jp, E-mail: P.Coles@sussex.ac.uk, E-mail: a.heavens@imperial.ac.uk [Imperial Centre for Inference and Cosmology, Blackett Laboratory, Prince Consort Road, London SW7 2AZ (United Kingdom)

    2016-04-01

    Lensing of the Cosmic Microwave Background (CMB) changes the morphology of pattern of temperature fluctuations, so topological descriptors such as Minkowski Functionals can probe the gravity model responsible for the lensing. We show how the recently introduced two-to-two and three-to-one kurt-spectra (and their associated correlation functions), which depend on the power spectrum of the lensing potential, can be used to probe modified gravity theories such as f ( R ) theories of gravity and quintessence models. We also investigate models based on effective field theory, which include the constant-Ω model, and low-energy Hořava theories. Estimates of the cumulative signal-to-noise for detection of lensing-induced morphology changes, reaches O(10{sup 3}) for the future planned CMB polarization mission COrE{sup +}. Assuming foreground removal is possible to ℓ{sub max}=3000, we show that many modified gravity theories can be rejected with a high level of significance, making this technique comparable in power to galaxy weak lensing or redshift surveys. These topological estimators are also useful in distinguishing lensing from other scattering secondaries at the level of the four-point function or trispectrum. Examples include the kinetic Sunyaev-Zel'dovich (kSZ) effect which shares, with lensing, a lack of spectral distortion. We also discuss the complication of foreground contamination from unsubtracted point sources.

  6. Conditional analysis of floating potential fluctuations at the edge of the Texas Experimental Tokamak Upgrade (TEXT-U)

    International Nuclear Information System (INIS)

    Filippas, A.V.; Bengston, R.D.; Li, G.; Meier, M.; Ritz, C.P.; Powers, E.J.

    1995-01-01

    Fluctuations in floating potential in the scrape-off layer and plasma edge were analyzed using a conditional statistical analysis technique. The floating potential fluctuations had a nearly Gaussian probability density function with the largest deviation from a Gaussian at the shear layer. The conditional averaging technique followed the statistical evolution of selected conditions in the floating potential signal. The decay rate of a conditional feature in time or space showed a small systematic variation with the amplitude of condition chosen. Either long-lived coherent structures are not present in statistically significant numbers, or the fluctuations are dominated by a large number of coherent structures with a nearly Gaussian distribution of fluctuation amplitudes, or conditional analysis using the amplitude of the floating potential as a condition is not a sensitive technique for identifying coherent structures

  7. Potential contact and intraocular lenses based on hydrophilic/hydrophobic sulfonated syndiotactic polystyrene membranes

    Directory of Open Access Journals (Sweden)

    Simona Zuppolini

    2017-10-01

    Full Text Available Crystalline films of syndiotactic polystyrene (s-PS, a commercially available thermoplastic polymer, having a highly hydrophilic amorphous phase, were achieved by using a mild solid-state sulfonation procedure. Despite the used mild process conditions, an easy and uniform sulfonation of the phenyl rings of the amorphous phase is obtained. The crystallinity of the polymer was not affect by the sulfonation degree (S, at least at S less than 20%, and the obtained polymer films show the nanoporous crystalline form of s-PS. As widely reported in literature, the nanoporous nature of the polymer crystalline phase gives to these materials the ability to absorb and release organic molecules of appropriate size and polarity. This property, coupled to transparency, makes these materials potentially useful intraocular lens (IOLs and contact lens applications. Sulfonation procedure and sulfonated film samples characterization by using wide-angle X-ray diffraction (WAXD, Fourier-transform infrared (FTIR and ultraviolet-visible (UV-vis spectroscopy techniques and water sorption tests were reported. Furthermore, the biocompatibility study demonstrated no cytotoxicity and appropriate cell interaction properties for the specific applications.

  8. Detection of the power spectrum of cosmic microwave background lensing by the Atacama Cosmology Telescope.

    Science.gov (United States)

    Das, Sudeep; Sherwin, Blake D; Aguirre, Paula; Appel, John W; Bond, J Richard; Carvalho, C Sofia; Devlin, Mark J; Dunkley, Joanna; Dünner, Rolando; Essinger-Hileman, Thomas; Fowler, Joseph W; Hajian, Amir; Halpern, Mark; Hasselfield, Matthew; Hincks, Adam D; Hlozek, Renée; Huffenberger, Kevin M; Hughes, John P; Irwin, Kent D; Klein, Jeff; Kosowsky, Arthur; Lupton, Robert H; Marriage, Tobias A; Marsden, Danica; Menanteau, Felipe; Moodley, Kavilan; Niemack, Michael D; Nolta, Michael R; Page, Lyman A; Parker, Lucas; Reese, Erik D; Schmitt, Benjamin L; Sehgal, Neelima; Sievers, Jon; Spergel, David N; Staggs, Suzanne T; Swetz, Daniel S; Switzer, Eric R; Thornton, Robert; Visnjic, Katerina; Wollack, Ed

    2011-07-08

    We report the first detection of the gravitational lensing of the cosmic microwave background through a measurement of the four-point correlation function in the temperature maps made by the Atacama Cosmology Telescope. We verify our detection by calculating the levels of potential contaminants and performing a number of null tests. The resulting convergence power spectrum at 2° angular scales measures the amplitude of matter density fluctuations on comoving length scales of around 100 Mpc at redshifts around 0.5 to 3. The measured amplitude of the signal agrees with Lambda cold dark matter cosmology predictions. Since the amplitude of the convergence power spectrum scales as the square of the amplitude of the density fluctuations, the 4σ detection of the lensing signal measures the amplitude of density fluctuations to 12%.

  9. 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 ...

  10. 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

  11. Phytoremediation of BTEX hydrocarbons: potential impacts of diurnal groundwater fluctuation on microbial degradation.

    Science.gov (United States)

    Weishaar, Jeff A; Tsao, David; Burken, Joel G

    2009-07-01

    Volatile hydrocarbons have multiple potential fates in phytoremediation. This research investigated the relationship between biodegradation and plant uptake of BTEX compounds in laboratory and field settings. At a phytoremediation site, preliminary studies revealed minimal uptake into trees and enhanced degradation potential in the rhizosphere and in the bulk soiL Increased oxygen transport to the vadose zone caused by diurnal rise and fall of the water table was hypothesized to enhance degradation in the bulk soil. A detailed greenhouse study was then conducted to investigate potential bioremediation impacts using field-site soil and DN34 hybrid poplar trees. In rhizosphere soils, the contaminated-planted reactor had significantly higher BTEX degrader populations versus the uncontaminated-planted reactor, as was anticipated. The bulk soil in the planted-contaminated reactor had increased degrader populations than the unplanted-contaminated soil or planted-uncontaminated soil, and planting increased degradation throughout the soil profile, not just in the limited volume of rhizosphere soils. Oxygen diffusive and advective transport into reactors was modeled and calculated. Oxygen input in planted reactors was at least 3 to 5 times higher than in unplanted reactors, and increasing oxygen input lead to increased degrader populations in a linear manner. These results combined with the knowledge that high-transpiration trees draw the contaminated groundwater to the capillary fringe and the rhizosphere indicate that phytoremediation can aid microbial degradation via multiple mechanisms: increasing degrader populations, increasing oxygen input via groundwater diurnal fluctuations, and transporting contaminants to the biologically-enriched soil profile.

  12. Potential effects of sea-level rise on the depth to saturated sediments of the Sagamore and Monomoy flow lenses on Cape Cod, Massachusetts

    Science.gov (United States)

    Walter, Donald A.; McCobb, Timothy D.; Masterson, John P.; Fienen, Michael N.

    2016-05-25

    In 2014, the U.S. Geological Survey, in cooperation with the Association to Preserve Cape Cod, the Cape Cod Commission, and the Massachusetts Environmental Trust, began an evaluation of the potential effects of sea-level rise on water table altitudes and depths to water on central and western Cape Cod, Massachusetts. Increases in atmospheric and oceanic temperatures arising, in part, from the release of greenhouse gases likely will result in higher sea levels globally. Increasing water table altitudes in shallow, unconfined coastal aquifer systems could adversely affect infrastructure—roads, utilities, basements, and septic systems—particularly in low-lying urbanized areas. The Sagamore and Monomoy flow lenses on Cape Cod are the largest and most populous of the six flow lenses that comprise the region’s aquifer system, the Cape Cod glacial aquifer. The potential effects of sea-level rise on water table altitude and depths to water were evaluated by use of numerical models of the region. The Sagamore and Monomoy flow lenses have a number of large surface water drainages that receive a substantial amount of groundwater discharge, 47 and 29 percent of the total, respectively. The median increase in the simulated water table altitude following a 6-foot sea-level rise across both flow lenses was 2.11 feet, or 35 percent when expressed as a percentage of the total sea-level rise. The response is nearly the same as the sea-level rise (6 feet) in some coastal areas and less than 0.1 foot near some large inland streams. Median water table responses differ substantially between the Sagamore and Monomoy flow lenses—at 29 and 49 percent, respectively—because larger surface water discharge on the Sagamore flow lens results in increased dampening of the water table response than in the Monomoy flow lens. Surface waters dampen water table altitude increases because streams are fixed-altitude boundaries that cause hydraulic gradients and streamflow to increase as sea

  13. Influence of temperature fluctuations during cryopreservation on vital parameters, differentiation potential, and transgene expression of placental multipotent stromal cells.

    Science.gov (United States)

    Pogozhykh, Denys; Pogozhykh, Olena; Prokopyuk, Volodymyr; Kuleshova, Larisa; Goltsev, Anatoliy; Blasczyk, Rainer; Mueller, Thomas

    2017-03-11

    Successful implementation of rapidly advancing regenerative medicine approaches has led to high demand for readily available cellular suspensions. In particular, multipotent stromal cells (MSCs) of placental origin have shown therapeutic efficiency in the treatment of numerous pathologies of varied etiology. Up to now, cryopreservation is the only effective way to preserve the viability and unique properties of such cells in the long term. However, practical biobanking is often associated with repeated temperature fluctuations or interruption of a cold chain due to various technical, transportation, and stocking events. While biochemical processes are expected to be suspended during cryopreservation, such temperature fluctuations may lead to accumulation of stress as well as to periodic release of water fractions in the samples, possibly leading to damage during long-term storage. In this study, we performed a comprehensive analysis of changes in cell survival, vital parameters, and differentiation potential, as well as transgene expression of placental MSCs after temperature fluctuations within the liquid nitrogen steam storage, mimicking long-term preservation in practical biobanking, transportation, and temporal storage. It was shown that viability and metabolic parameters of placental MSCs did not significantly differ after temperature fluctuations in the range from -196 °C to -100 °C in less than 20 cycles in comparison to constant temperature storage. However, increasing the temperature range to -80 °C as well as increasing the number of cycles leads to significant lowering of these parameters after thawing. The number of apoptotic changes increases depending on the number of cycles of temperature fluctuations. Besides, adhesive properties of the cells after thawing are significantly compromised in the samples subjected to temperature fluctuations during storage. Differentiation potential of placental MSCs was not compromised after cryopreservation

  14. Unbounded 1/f-spectrum from quantum fluctuations of the Coulomb potential at finite temperature

    International Nuclear Information System (INIS)

    Kazakov, Kirill A.

    2008-01-01

    Experimentally observed unboundedness of flicker noise spectrum is explained on the basis of a finite-temperature theory of quantum electromagnetic fluctuations produced by electrons in an external electric field. Account of the photon heat bath and external field effects results in a 1/f-contribution to the power spectrum of fluctuations, which is odd in frequency, and gives rise to a finite contribution to the voltage correlation function. The derived expression is shown to be in agreement with the experimental data on flicker noise measurements in metal films

  15. Dynamics of 2-D one electron quantum dots in periodically fluctuating confinement potential: Influence of size and anharmonicity

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Parikshit [Department of Chemistry, Physical Chemistry Section, Visva Bharati University, Santiniketan, Birbhum 731 235, West Bengal (India); Ghosh, Manas, E-mail: pcmg77@rediffmail.co [Department of Chemistry, Physical Chemistry Section, Visva Bharati University, Santiniketan, Birbhum 731 235, West Bengal (India)

    2009-11-15

    We explore the dynamics of harmonically confined single electron quantum dots as a function of dot size under periodically fluctuating confinement potential. The system of interest is a 2-D system in the presence of a perpendicular magnetic field. We show that for given strengths of the magnetic field and effective mass, a periodic variation in the strength of the confinement potential could invite interesting features in the dynamics of the system. Also, the pattern of time evolution of eigenstates of the unperturbed system reveals significant size-dependence. The fluctuation in the confinement potential from its initial value is found to modulate the dynamical aspects in a prominent way. The presence of cubic anharmonicity in the confining field brings in new features in the dot dynamics.

  16. Potential fluctuations due to randomly distributed charges at the semiconductor-insulator interface in MIS-structures

    CERN Document Server

    Yanchev, I

    2003-01-01

    A new expression for the Fourier transform of the binary correlation function of the random potential near the semiconductor-insulator interface is derived. The screening from the metal electrode in MIS-structure is taken into account introducing an effective insulator thickness. An essential advantage of this correlation function is the finite dispersion of the random potential to which it leads in distinction with the so far known correlation functions leading to a divergent dispersion. The dispersion, an important characteristic of the random potential distribution, determining the amplitude of the potential fluctuations is calculated.

  17. 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.

  18. Detrended fluctuation analysis of compound action potentials re-corded in the cutaneous nerves of diabetic rats

    International Nuclear Information System (INIS)

    Quiroz-González, Salvador; Rodríguez-Torres, Erika Elizabeth; Segura-Alegría, Bertha; Pereira-Venegas, Javier; Lopez-Gomez, Rosa Estela; Jiménez-Estrada, Ismael

    2016-01-01

    Highlights: • Fractal analysis of compound action potentials (CAP) evoked in diabetic nerves. • Diabetic rats showed an increment in the chaotic behavior of CAP responses. • Diabetes provokes impaired transmission of sensory information in rats. - Abstract: The electrophysiological alterations in nerves due to diabetes are classically studied in relation to their instantaneous frequency, conduction velocity and amplitude. However, analysis of amplitude variability may reflect the occurrence of feedback loop mechanisms that adjust the output as a function of its previous activity could indicate fractal dynamics. We assume that a peripheral neuropathy, such as that evoked by diabetes, the inability to maintain a steady flow of sensory information is reflected as a breakdown of the long range power-law correlation of CAP area fluctuation from cutaneous nerves. To test this, we first explored in normal rats whether fluctuations in the trial-to-trial CAP area showed a self-similar behavior or fractal structure by means of detrended fluctuations analysis (DFA), and Poincare plots. In addition, we determine whether such CAP fluctuations varied by diabetes induction. Results showed that CAP area fluctuation of SU nerves evoked in normal rats present a long term correlation and self-similar organization (fractal behavior) from trial to trial stimulation as evidenced by DFA of CAP areas. However, CAPs recorded in diabetic nerves exhibited significant reductions in area, larger duration and increased area variability and different Poincare plots than control nerves. The Hurst exponent value determined with the DFA method from a series of 2000 CAPs evoked in diabetic SU nerves was smaller than in control nerves. It is proposed that in cutaneous nerves of normal rats variability of the CAP area present a long term correlation and self-similar organization (fractal behavior), and reflect the ability to maintain a steady flow of sensory information through cutaneous nerves

  19. 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.

  20. 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

  1. Potential Fluctuations and Localization Effects in CZTS Single Crystals, as Revealed by Optical Spectroscopy

    Science.gov (United States)

    Bleuse, Joël; Ducroquet, Frédérique; Mariette, Henri

    2018-03-01

    Reports on Cu_2 ZnSn(S_x Se_{1-x} )_4 (CZTSSe) solar cell devices all show an open-circuit voltage lower than expected, especially when compared to CuIn_x Ga_{1-x} (S,Se)_2 devices, which reduces their power efficiency and delays their development. A high concentration of intrinsic defects in CZTSSe, and their stabilization through neutral complex formation, which induces some local fluctuations, are at the origin of local energy shifts in the conduction and valence band edges. The implied band tail in Cu_2 ZnSnS_4 is studied in this work by combining three types of optical spectroscopy data: emission spectra compared to photoluminescence excitation spectroscopy, emission spectra as a function of excitation power, and time-resolved photoluminescence spectra. All these data converge to show that both the bandgap and the band tail of localized states just below are dependent on the degree of order/disorder in the Cu/Zn cation sublattice of the quaternary structure: in the more ordered structures, the bandgap increases by about 50 meV, and the energy range of the band tail is decreased from about 110 to 70 meV.

  2. 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

  3. The nature of electrostatic potential fluctuations in Cu2ZnSnS4 and their role on photovoltaic device performance

    International Nuclear Information System (INIS)

    Mendis, B G; Goodman, M C J; Taylor, A A; Halliday, D P; Shannon, M D; Major, J D; Durose, K

    2013-01-01

    Aberration corrected STEM EELS is used to investigate point defects in Cu 2 ZnSnS 4 (CZTS). Nano-scale clusters of Zn Cu anti-site donors are observed with the donor concentration being sufficiently high to degenerately dope the semiconductor. Uncompensated donors and acceptors result in electrostatic potential fluctuations within the material. The effect of these potential fluctuations on the photovoltaic device properties is discussed

  4. An analysis of the fluctuation potential in the modified Poisson-Boltzmann theory for restricted primitive model electrolytes

    Directory of Open Access Journals (Sweden)

    E.O. Ulloa-Dávila

    2017-12-01

    Full Text Available An approximate analytical solution to the fluctuation potential problem in the modified Poisson-Boltzmann theory of electrolyte solutions in the restricted primitive model is presented. The solution is valid for all inter-ionic distances, including contact values. The fluctuation potential solution is implemented in the theory to describe the structure of the electrolyte in terms of the radial distribution functions, and to calculate some aspects of thermodynamics, viz., configurational reduced energies, and osmotic coefficients. The calculations have been made for symmetric valence 1:1 systems at the physical parameters of ionic diameter 4.25·10^{-10} m, relative permittivity 78.5, absolute temperature 298 K, and molar concentrations 0.1038, 0.425, 1.00, and 1.968. Radial distribution functions are compared with the corresponding results from the symmetric Poisson-Boltzmann, and the conventional and modified Poisson-Boltzmann theories. Comparisons have also been done for the contact values of the radial distributions, reduced configurational energies, and osmotic coefficients as functions of electrolyte concentration. Some Monte Carlo simulation data from the literature are also included in the assessment of the thermodynamic predictions. Results show a very good agreement with the Monte Carlo results and some improvement for osmotic coefficients and radial distribution functions contact values relative to these theories. The reduced energy curve shows excellent agreement with Monte Carlo data for molarities up to 1 mol/dm^3.

  5. 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…

  6. The inner mass power spectrum of galaxies using strong gravitational lensing: beyond linear approximation

    Science.gov (United States)

    Chatterjee, Saikat; Koopmans, Léon V. E.

    2018-02-01

    In the last decade, the detection of individual massive dark matter sub-haloes has been possible using potential correction formalism in strong gravitational lens imaging. Here, we propose a statistical formalism to relate strong gravitational lens surface brightness anomalies to the lens potential fluctuations arising from dark matter distribution in the lens galaxy. We consider these fluctuations as a Gaussian random field in addition to the unperturbed smooth lens model. This is very similar to weak lensing formalism and we show that in this way we can measure the power spectrum of these perturbations to the potential. We test the method by applying it to simulated mock lenses of different geometries and by performing an MCMC analysis of the theoretical power spectra. This method can measure density fluctuations in early type galaxies on scales of 1-10 kpc at typical rms levels of a per cent, using a single lens system observed with the Hubble Space Telescope with typical signal-to-noise ratios obtained in a single orbit.

  7. 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....

  8. Potential fluctuations in graphene due to correlated charged impurities in substrate

    OpenAIRE

    Anicic, Rastko; Miskovic, Zoran

    2013-01-01

    We evaluate the autocorrelation function of the electrostatic potential in doped graphene due to nearby charged impurities. The screening of those impurities is described by a combination of the polarization function for graphene in random phase approximation with the electrostatic Green's function of the surrounding dielectrics. Using the hard-disk model for a two-dimensional distribution of impurities, we show that large correlation lengths between impurities can give rise to anti-correlati...

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. 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.

  14. Synaptic inhibition and excitation estimated via the time constant of membrane potential fluctuations

    DEFF Research Database (Denmark)

    Berg, Rune W.; Ditlevsen, Susanne

    2013-01-01

    and excitation and their confidence limits from single sweep trials. The estimates are based on the mean membrane potential, (V) , and the membrane time constant,τ. The time constant provides the total conductance (G = capacitance/τ) and is extracted from the autocorrelation of V. The synaptic conductances can...... then be inferred from (V) when approximating the neuron as a single compartment. We further employ a stochastic model to establish limits of confidence. The method is verified on models and experimental data, where the synaptic input is manipulated pharmacologically or estimated by an alternative method....... The method gives best results if the synaptic input is large compared to other conductances, the intrinsic conductances have little or no time dependence or are comparably small, the ligand gated kinetics is faster than the membrane time constant, and the majority of synaptic contacts are electrotonically...

  15. Signature of a Nonharmonic Potential as Revealed from a Consistent Shape and Fluctuation Analysis of an Adherent Membrane

    Directory of Open Access Journals (Sweden)

    Daniel Schmidt

    2014-05-01

    Full Text Available The interaction of fluid membranes with a scaffold, which can be a planar surface or a more complex structure, is intrinsic to a number of systems from artificial supported bilayers and vesicles to cellular membranes. In principle, these interactions can be either discrete and protein mediated, or continuous. In the latter case, they emerge from ubiquitous intrinsic surface interaction potentials as well as nature-designed steric contributions of the fluctuating membrane or from the polymers of the glycocalyx. Despite the fact that these nonspecific potentials are omnipresent, their description has been a major challenge from experimental and theoretical points of view. Here, we show that a full understanding of the implications of the continuous interactions can be achieved only by expanding the standard superposition models commonly used to treat these types of systems, beyond the usual harmonic level of description. Supported by this expanded theoretical framework, we present three independent, yet mutually consistent, experimental approaches to measure the interaction potential strength and the membrane tension. Upon explicitly taking into account the nature of shot noise as well as the nature of finite experimental resolution, excellent agreement with the augmented theory is obtained, which finally provides a coherent view of the behavior of the membrane in the vicinity of a scaffold.

  16. Influence of chain topology and bond potential on the glass transition of polymer chains simulated with the bond fluctuation model

    Energy Technology Data Exchange (ETDEWEB)

    Freire, J J [Departamento de Ciencias y Tecnicas FisicoquImicas, Facultad de Ciencias, Universidad Nacional de Educacion a Distancia (UNED), Senda del Rey 9, 28040 Madrid (Spain)], E-mail: jfreire@invi.uned.es

    2008-07-16

    The bond fluctuation model with a bond potential has been applied to investigation of the glass transition of linear chains and chains with a regular disposition of small branches. Cooling and subsequent heating curves are obtained for the chain energies and also for the mean acceptance probability of a bead jump. In order to mimic different trends to vitrification, a factor B gauging the strength of the bond potential with respect to the long-range potential (i.e. the intramolecular or intermolecular potential between indirectly bonded beads) has been introduced. (A higher value of B leads to a preference for the highest bond lengths and a higher total energy, implying a greater tendency to vitrify.) Different cases have been considered for linear chains: no long-range potential, no bond potential and several choices for B. Furthermore, two distinct values of B have been considered for alternate bonds in linear chains. In the case of the branched chains, mixed models with different values of B for bonds in the main chain and in the branches have also been investigated. The possible presence of ordering or crystallization has been characterized by calculating the collective light scattering function of the different samples after annealing at a convenient temperature below the onset of the abrupt change in the curves associated with a thermodynamic transition. It is concluded that ordering is inherited more efficiently in the systems with branched chains and also for higher values of B. The branched molecules with the highest B values in the main chain bonds exhibit two distinct transitions in the heating curves, which may be associated with two glass transitions. This behavior has been detected experimentally for chains with relatively long flexible branches.

  17. 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

  18. 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...

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Fluctuations of estradiol during women's menstrual cycle: Influences on reactivity towards erotic stimuli in the late positive potential.

    Science.gov (United States)

    Munk, Aisha J L; Zoeller, Aaron C; Hennig, Juergen

    2018-05-01

    While several studies examined the reactivity towards negative emotional stimuli across women's menstrual cycle, only few investigated responses to positive emotional cues in association with sexual hormones on a neural level. Therefore, the aim of the current EEG-experiment was to study the differential reactivity towards positive (erotic) words during the menstrual cycle (i.e. with fluctuations in the steroids estradiol and progesterone) in the late positive potential (LPP). Regarding reactivity towards erotic stimuli, the LPP is seen as the most relevant ERP-component, as more positive amplitudes in the LPP reflect larger incentive salience and higher arousal. The LPP towards erotic words was expected to be more pronounced during fertile phases of the menstrual cycle (around ovulation). Furthermore, associations with hormonal concentrations of estradiol and progesterone were investigated. 19 young, free cycling women were tested in an Erotic Stroop paradigm during the follicular phase, ovulation, and the luteal phase in a balanced cross-over design, while electroencephalogram (EEG) was recorded. LPPs in reaction to erotic compared to neutral words were larger in every phase. During the follicular phase and ovulation, higher estradiol-concentrations were associated with more positive LPP-amplitudes towards erotic- than to neutral words. No effects of progesterone, as well as no effects of cycle phase, were evident. Results are being discussed regarding implications for further research. Copyright © 2018 Elsevier Ltd. All rights reserved.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Quantum fluctuations of the Coulomb potential as a source of flicker noise: the influence of external electric field

    International Nuclear Information System (INIS)

    Kazakov, Kirill A

    2006-01-01

    Fluctuations of the electromagnetic field produced by quantized matter in an external electric field are investigated. A general expression for the power spectrum of fluctuations is derived within the long-range expansion. It is found that in the whole measured frequency band, the power spectrum of fluctuations exhibits an inverse frequency dependence. A general argument is given showing that for all practically relevant values of the electric field, the power spectrum of induced fluctuations is proportional to the field strength squared. As an illustration, the power spectrum is calculated explicitly using a kinetic model with a relaxation-type collision term. Finally, it is shown that the magnitude of fluctuations produced by a sample generally has a Gaussian distribution around its mean value, and its dependence on the sample geometry is determined. In particular, it is demonstrated that for geometrically similar samples the power spectrum is inversely proportional to the sample volume. Application of the results obtained to the problem of flicker noise is discussed

  9. 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.

  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. 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 ...

  12. 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.

  13. 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.

  14. Energy Fluctuation of Ideal Fermi Gas Trapped under Generic Power Law Potential U=\\sum_{i=1}^{d} c_i\\vert x_{i}/a_{i}\\vert^{n_{i} } in d Dimensions

    Science.gov (United States)

    Mir, Mehedi Faruk; Muktadir Rahman, Md.; Dwaipayan, Debnath; Sakhawat Hossain Himel, Md.

    2016-04-01

    Energy fluctuation of ideal Fermi gas trapped under generic power law potential U=\\sumi=1d ci \\vertxi/ai \\vert n_i has been calculated in arbitrary dimensions. Energy fluctuation is scrutinized further in the degenerate limit μ ≫ KBT with the help of Sommerfeld expansion. The dependence of energy fluctuation on dimensionality and power law potential is studied in detail. Most importantly our general result can not only exactly reproduce the recently published result regarding free and harmonically trapped ideal Fermi gas in d = 3 but also can describe the outcome for any power law potential in arbitrary dimension.

  15. Quantum fluctuations

    International Nuclear Information System (INIS)

    Reynaud, S.; Giacobino, S.; Zinn-Justin, J.

    1997-01-01

    This course is dedicated to present in a pedagogical manner the recent developments in peculiar fields concerned by quantum fluctuations: quantum noise in optics, light propagation through dielectric media, sub-Poissonian light generated by lasers and masers, quantum non-demolition measurements, quantum electrodynamics applied to cavities and electrical circuits involving superconducting tunnel junctions. (A.C.)

  16. 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...

  17. Modification of defects and potential fluctuations in slow-cooled and quenched Cu2ZnSnSe4 single crystals

    Science.gov (United States)

    Bishop, Douglas M.; McCandless, Brian; Gershon, Talia; Lloyd, Michael A.; Haight, Richard; Birkmire, Robert

    2017-02-01

    Recent literature reports have shown the ability to manipulate Cu-Zn cation ordering for Cu2ZnSnSe4 (CZTSe) via low temperature treatments. Theoretical arguments suggest that one of the major roadblocks to higher VOC—significant band tailing—could be improved with increased cation order; however, few direct measurements have been reported and significant device improvements have not yet been realized. This report investigates electrical properties, defects, and devices from quenched and slow-cooled single crystals of CZTSe. The extent of disorder was characterized by Raman spectroscopy as well as x-ray diffraction, where the change in Cu-Zn order can be detected by a changing c/a ratio. Quenched samples show higher acceptor concentrations, lower hole mobilities, and a lower-energy photoluminescence (PL) peak than crystals cooled at slower rates, consistent with a reduction in the bandgap. In addition, samples quenched at the highest temperatures showed lower PL yield consistent with higher quantities of deep defects. Devices fabricated using slow-cooled CZTSe single crystals showed improved efficiencies, most notably with increased VOC; however, low temperature intensity-dependent photoluminescence measurements continue to indicate the existence of potential fluctuations. We discuss the possibility that potential fluctuations in slow-cooled samples may be related to the inability to achieve a long range order of the Cu-Zn sub-lattice resulting in local regions of high and low levels of cation order, and consequent local variations in the bandgap. The presence of significant potential fluctuations, even after the slow-cooling step, suggests the difficulty in eliminating band-tailing in this system, and thus, additional approaches may be needed for significant reduction of the VOC deficit.

  18. 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.

  19. 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)

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. Redox potential dynamics in a horizontal subsurface flow constructed wetland for wastewater treatment: Diel, seasonal ans spatial fluctuations

    Czech Academy of Sciences Publication Activity Database

    Dušek, Jiří; Picek, T.; Čížková, Hana

    2008-01-01

    Roč. 34, - (2008), s. 223-232 ISSN 0925-8574 Institutional research plan: CEZ:AV0Z60870520 Keywords : Redox potential * Redox prosesses * Phragmites australis * Wastewater treatment s * Constructed wetlands * Contunuous measurement Subject RIV: DJ - Water Pollution ; Quality Impact factor: 1.836, year: 2008

  5. 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.

  6. Magnetic fluctuations associated with density fluctuations in the tokamak edge

    International Nuclear Information System (INIS)

    Kim, Y.J.; Gentle, K.W.; Ritz, C.P.; Rhodes, T.L.; Bengtson, R.D.

    1989-01-01

    Electrostatic density and potential fluctuations occurring with high amplitude near the edge of a tokamak are correlated with components of the fluctuating magnetic field measured outside the limiter radius. It has been established that this turbulence is associated with fluctuations in current as well as density and potential. The correlation extends for substantial toroidal distances, but only if the probes are displaced approximately along field lines, consistent with the short coherence lengths poloidally but long coherence lengths parallel to the field which are characteristic for this turbulence. Furthermore, the correlation can be found only with density fluctuations measured inside the limiter radius; density fluctuations behind the limiter have no detectable magnetic concomitant for the toroidally spaced probes used here. (author). Letter-to-the-editor. 12 refs, 3 figs

  7. Noise Estimates for Measurements of Weak Lensing from the Lyman-alpha Forest

    Science.gov (United States)

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

    2018-03-01

    Lensing changes the apparent separation between pixels in the Lyman-α forest of separate quasars or high redshift objects by changing their observed positions on the sky. This changes the implied correlations in the absorption and in particular makes the Lyman-α forest correlation function, or power spectrum, locally anisotropic in the plane of the sky. We have proposed a method for measuring weak lensing using this effect. Here we estimate the noise expected in weak lensing maps and power spectra for different sets of observational parameters. We find that surveys of the size and quality of the ones being done today and ones planned for the future will be able to measure the lensing power spectrum at a source redshift of z ≃ 2.5 with high precision and even be able to image the distribution of foreground matter with high fidelity on degree scales. For example, we predict that Lyman-α forest lensing measurements from the DESI and WEAVE surveys should yield the mass fluctuation amplitude with a statistical error of ˜3%, eBOSS ˜6%. and the proposed MSE survey less than 1%. By dividing the redshift range into multiple bins some tomographic lensing information should be accessible as well. This would allow for cosmological lensing measurements at higher redshift than are accessible with galaxy shear surveys and correspondingly better constraints on the evolution of dark energy at relatively early times.

  8. Potential distribution of Podocnemis lewyana (Reptilia: Podocnemididae) and its possible fluctuation under different global climate change scenarios

    International Nuclear Information System (INIS)

    Ortiz Yusty, Carlos; Restrepo, Adriana; Paez, Vivian P

    2014-01-01

    We implemented a species distribution modelling approach to establish the potential distribution of Podocnemis lewyana, to explore the climatic factors that may influence the species' distribution and to evaluate possible changes in distribution under future climate scenarios. The distribution models predicted a continuous distribution from south to north along the Magdalena River, from Rivera and Palermo in the Department of Huila to the departments of Atlantico and Magdalena in the north. Temperature was the variable most influential in the distribution of P. lewyana; this species tends to be present in warm regions with low temperature variability. The distribution model predicted an increase in the geographic range of P. lewyana under climate change scenarios. However, taking into account the habitat preferences of this species and its strong association with water, this result should be treated with caution since the model considered only terrestrial climatic variables. Given the life history characteristics of this species (temperature dependent sex determination, high pivotal temperature and a very narrow transition range) and the negative effect of changes in hydrological regimes on embryo survival, expansion of the potential distribution of P. lewyana in the future does not mean that the species will not be affected by global climate change.

  9. 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.

  10. Fluctuation analysis

    International Nuclear Information System (INIS)

    Clarke, J.

    1980-01-01

    This paper briefly reviews sources of noise in Josephson junctions, and the limits they impose on the sensitivity of dc and rf SQUIDS. The results are strictly valid only for a resistively shunted junction (RSJ) with zero capacitance, but should be applicable to point contact junctions and microbridges in so far as these devices can be approximated by the RSJ model. Fluctuations arising from Nyquist noise in the resistive shunt of a single junction are discussed in the limit eI/sub o/R/k/sub B/T << 1 in which a classical treatment is appropriate, and then extend the treatment to the limit eI/sub o/R/k/sub B/T greater than or equal to 1 in which quantum effects become important. The Nyquist limit theory is used to calculate the noise in a dc SQUID, and the results are compared with a number of practical devices. The quantum limit is briefly considered. Results for the predicted sensitivity of rf SQUIDS are presented, and also compared with a number of practical devices. Finally, the importance of l/f noise (f is the frequency) in limiting the low frequency performance of SQUIDS is discussed

  11. 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.

  12. 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.

  13. 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.

  14. Terrestrial Gravity Fluctuations

    Directory of Open Access Journals (Sweden)

    Jan Harms

    2015-12-01

    Full Text Available Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10^–23 Hz^–1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our

  15. Terrestrial Gravity Fluctuations

    Science.gov (United States)

    Harms, Jan

    2015-12-01

    Different forms of fluctuations of the terrestrial gravity field are observed by gravity experiments. For example, atmospheric pressure fluctuations generate a gravity-noise foreground in measurements with super-conducting gravimeters. Gravity changes caused by high-magnitude earthquakes have been detected with the satellite gravity experiment GRACE, and we expect high-frequency terrestrial gravity fluctuations produced by ambient seismic fields to limit the sensitivity of ground-based gravitational-wave (GW) detectors. Accordingly, terrestrial gravity fluctuations are considered noise and signal depending on the experiment. Here, we will focus on ground-based gravimetry. This field is rapidly progressing through the development of GW detectors. The technology is pushed to its current limits in the advanced generation of the LIGO and Virgo detectors, targeting gravity strain sensitivities better than 10-23 Hz-1/2 above a few tens of a Hz. Alternative designs for GW detectors evolving from traditional gravity gradiometers such as torsion bars, atom interferometers, and superconducting gradiometers are currently being developed to extend the detection band to frequencies below 1 Hz. The goal of this article is to provide the analytical framework to describe terrestrial gravity perturbations in these experiments. Models of terrestrial gravity perturbations related to seismic fields, atmospheric disturbances, and vibrating, rotating or moving objects, are derived and analyzed. The models are then used to evaluate passive and active gravity noise mitigation strategies in GW detectors, or alternatively, to describe their potential use in geophysics. The article reviews the current state of the field, and also presents new analyses especially with respect to the impact of seismic scattering on gravity perturbations, active gravity noise cancellation, and time-domain models of gravity perturbations from atmospheric and seismic point sources. Our understanding of

  16. 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.

  17. 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.

  18. 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

  19. 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…

  20. 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.

  1. 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...

  2. 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

  3. Fluctuations in quantum chaos

    International Nuclear Information System (INIS)

    Casati, G.; Chirikov, B.V.

    1996-01-01

    Various fluctuations in quantum systems with discrete spectrum are discussed, including recent unpublished results. Open questions and unexplained peculiarities of quantum fluctuations are formulated [ru

  4. Fluctuations in Cerebral Hemodynamics

    National Research Council Canada - National Science Library

    Latka, Miroslaw

    2003-01-01

    We demonstrate that the scaling properties of intracranial pressure (ICP) fluctuations and fluctuations of blood flow velocity in middle cerebral arteries are characterized by two scaling exponents...

  5. Constraints on the dark matter and dark energy interactions from weak lensing bispectrum tomography

    Energy Technology Data Exchange (ETDEWEB)

    An, Rui [School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Feng, Chang [Department of Physics and Astronomy, University of California, Irvine, CA 92697 (United States); Wang, Bin, E-mail: an_rui@sjtu.edu.cn, E-mail: chang.feng@uci.edu, E-mail: wang_b@sjtu.edu.cn [Center for Gravitation and Cosmology, College of Physical Science and Technology, Yangzhou University, Yangzhou 225009 (China)

    2017-10-01

    We estimate uncertainties of cosmological parameters for phenomenological interacting dark energy models using weak lensing convergence power spectrum and bispectrum. We focus on the bispectrum tomography and examine how well the weak lensing bispectrum with tomography can constrain the interactions between dark sectors, as well as other cosmological parameters. Employing the Fisher matrix analysis, we forecast parameter uncertainties derived from weak lensing bispectra with a two-bin tomography and place upper bounds on strength of the interactions between the dark sectors. The cosmic shear will be measured from upcoming weak lensing surveys with high sensitivity, thus it enables us to use the higher order correlation functions of weak lensing to constrain the interaction between dark sectors and will potentially provide more stringent results with other observations combined.

  6. 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.

  7. 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

  8. 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...

  9. 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.

  10. Measuring vascular reactivity with resting-state blood oxygenation level-dependent (BOLD) signal fluctuations: A potential alternative to the breath-holding challenge?

    Science.gov (United States)

    Jahanian, Hesamoddin; Christen, Thomas; Moseley, Michael E; Pajewski, Nicholas M; Wright, Clinton B; Tamura, Manjula K; Zaharchuk, Greg

    2017-07-01

    Measurement of the ability of blood vessels to dilate and constrict, known as vascular reactivity, is often performed with breath-holding tasks that transiently raise arterial blood carbon dioxide (P a CO 2 ) levels. However, following the proper commands for a breath-holding experiment may be difficult or impossible for many patients. In this study, we evaluated two approaches for obtaining vascular reactivity information using blood oxygenation level-dependent signal fluctuations obtained from resting-state functional magnetic resonance imaging data: physiological fluctuation regression and coefficient of variation of the resting-state functional magnetic resonance imaging signal. We studied a cohort of 28 older adults (69 ± 7 years) and found that six of them (21%) could not perform the breath-holding protocol, based on an objective comparison with an idealized respiratory waveform. In the subjects that could comply, we found a strong linear correlation between data extracted from spontaneous resting-state functional magnetic resonance imaging signal fluctuations and the blood oxygenation level-dependent percentage signal change during breath-holding challenge ( R 2  = 0.57 and 0.61 for resting-state physiological fluctuation regression and resting-state coefficient of variation methods, respectively). This technique may eliminate the need for subject cooperation, thus allowing the evaluation of vascular reactivity in a wider range of clinical and research conditions in which it may otherwise be impractical.

  11. Lensed Density Perturbations in Braneworlds An Alternative to Perturbations from Inflation

    CERN Document Server

    Chung, D J H; Chung, Daniel J. H.; Freese, Katherine

    2003-01-01

    We consider a scenario in which our observable universe is a 3-dimensional surface (3-brane) living in extra dimensions with a warped geometry. We show that ``lensed'' density perturbations from other branes serve as possible seeds for structure formation on our observable brane (without inflation), and, in addition, provide constraints on braneworld scenarios with warped bulk geometry. Due to the warped bulk metric, any perturbation generated on one brane (or in the bulk matter) appears to an observer on a second brane to have a significantly different amplitude. We analyze lensed perturbations in the Randall-Sundrum type scenarios and the ``shortcut metric'' scenarios. For Lorentz violating metrics in the bulk, we find the attractive possibility that large density fluctuations that are causally produced elsewhere can lead to small density fluctuations on our brane on superhorizon (acausal) length scales, as required by structure formation. Our most interesting result is that the ``shortcut metrics'' in whic...

  12. Weak gravitational lensing as a method to constrain unstable dark matter

    International Nuclear Information System (INIS)

    Wang Meiyu; Zentner, Andrew R.

    2010-01-01

    The nature of the dark matter remains a mystery. The possibility of an unstable dark matter particle decaying to invisible daughter particles has been explored many times in the past few decades. Meanwhile, weak gravitational lensing shear has gained a lot of attention as a probe of dark energy, though it was previously considered a dark matter probe. Weak lensing is a useful tool for constraining the stability of the dark matter. In the coming decade a number of large galaxy imaging surveys will be undertaken and will measure the statistics of cosmological weak lensing with unprecedented precision. Weak lensing statistics are sensitive to unstable dark matter in at least two ways. Dark matter decays alter the matter power spectrum and change the angular diameter distance-redshift relation. We show how measurements of weak lensing shear correlations may provide the most restrictive, model-independent constraints on the lifetime of unstable dark matter. Our results rely on assumptions regarding nonlinear evolution of density fluctuations in scenarios of unstable dark matter and one of our aims is to stimulate interest in theoretical work on nonlinear structure growth in unstable dark matter models.

  13. 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)

  14. 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.

  15. Fluctuations in LC Oscillators

    Directory of Open Access Journals (Sweden)

    O. Ondracek

    1994-03-01

    Full Text Available An analysis of the phase and amplitude fluctuations in oscillators with simple resonant circuit is presented. Negative feedback is used to minimize effect of the inherent noise produced by bipolar transistor on fluctuation characteristics.

  16. In vitro adhesion of Acanthamoeba castellanii to soft contact lenses depends on water content and disinfection procedure.

    Science.gov (United States)

    Reverey, Julia F; Fromme, Roland; Leippe, Matthias; Selhuber-Unkel, Christine

    2014-08-01

    To compare the potential of different soft contact lenses to be contaminated with Acanthamoeba castellanii as a function of material parameters and cleaning procedures. Different unworn soft hydrogel and silicone hydrogel contact lenses were incubated with human pathogenic A. castellanii. The adhesion of the acanthamoebae was investigated on the contact lenses and put into relation to their material parameters. The efficacy of a recommended contact lens cleaning procedure in reducing A. castellanii adhesion was investigated. We found that material parameters such as elastic modulus, silicone content, ionic properties and swelling do not influence the adhesion of acanthamoebae to soft contact lenses. A material parameter that influenced adhesion significantly was the water content of the lens. With increasing water content, the adhesion of acanthamoebae increased. By following the cleaning instructions of the manufacturer the contamination of the lenses with A. castellanii could be reduced to a minimum, as shown both on contact lenses and in control experiments. With this study we show that for the tested lenses, the adhesion of A. castellanii to contact lenses is independent of the silicone content of the lens, but depends nonlinearly on the water content of the lens. Furthermore, we demonstrate that applying proper lens cleaning procedures minimizes the risk of acanthamoebae adhesion to contact lenses. Copyright © 2013 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  17. Ocular Drug Delivery through pHEMA-Hydrogel Contact Lenses Co-Loaded with Lipophilic Vitamins

    Science.gov (United States)

    Lee, Dasom; Cho, Seungkwon; Park, Hwa Sung; Kwon, Inchan

    2016-09-01

    Ocular drug delivery through hydrogel contact lenses has great potential for the treatment of ocular diseases. Previous studies showed that the loading of lipophilic vitamin E to silicone-hydrogel contact lenses was beneficial in ocular drug delivery. We hypothesized that vitamin E loading to another type of popular hydrogel contact lenses, pHEMA-hydrogel contact lenses, improves ocular drug delivery by increasing the drug loading or the duration of drug release. Loading of vitamin E to pHEMA-hydrogel contact lenses significantly increased the loading of a hydrophilic drug surrogate (Alexa Fluor 488 dye) and two hydrophilic glaucoma drugs (timolol and brimonidine) to the lenses by 37.5%, 19.1%, and 18.7%, respectively. However, the release duration time was not significantly altered. Next, we hypothesized that the lipophilic nature of vitamin E attributes to the enhanced drug loading. Therefore, we investigated the effects of co-loading of another lipophilic vitamin, vitamin A, on drug surrogate delivery. We found out that vitamin A loading also increased the loading of the drug surrogate to pHEMA-hydrogel contact lenses by 30.3%. Similar to vitamin E loading, vitamin A loading did not significantly alter the release duration time of the drug or drug surrogate.

  18. Microbiologic study of soft contact lenses after laser subepithelial keratectomy for myopia.

    Science.gov (United States)

    Hondur, Ahmet; Bilgihan, Kamil; Cirak, Meltem Yalinay; Dogan, Ozgur; Erdinc, Alper; Hasanreisoglu, Berati

    2008-01-01

    To evaluate the extent and agents of bacterial contamination of bandage disposable soft contact lenses after laser subepithelial keratectomy (LASEK) and to correlate the findings with clinical data. Disposable soft contact lenses were collected from 52 eyes of 26 consecutive patients treated with LASEK for myopia. The patients were treated with a fixed combination of tobramycin and diclofenac until epithelial closure. The lenses were removed on the fourth or fifth postoperative day with sterile forceps and immediately placed in sterile tubes containing culture media brain-heart infusion broth. The lenses were evaluated for microbial colonization. Of the 52 contact lenses analyzed, six (11.5%) had positive cultures. However, no clinical finding of infection was noted. Isolated microorganisms were coagulase-negative staphylococci (two lenses), Stenotrophomonas maltophilia (two lenses), Acinetobacter species (one lens), and Aeromonas hydrophila (one lens). Except for one case, the microorganisms were sensitive to the administered antibiotic. The risk of infectious keratitis after LASEK seems to be low. Except for staphylococci, the isolated microorganisms have not been previously reported to colonize the ocular surface or cause keratitis after refractive surgery. These findings may suggest a changing trend of potentially infectious agents after surface ablation.

  19. 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.

  20. 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

  1. 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

  2. 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 ...

  3. Microbial contamination of soft contact lenses & accessories in asymptomatic contact lens users

    OpenAIRE

    Deeksha V Thakur; Ujjwala N Gaikwad

    2014-01-01

    Background & objectives: With increasing use of soft contact lenses the incidence of contact lens induced infections is also increasing. This study was aimed to assess the knowledge of new and existing contact lens users about the risk of microbial contamination associated with improper use and maintenance of contact lenses, type of microbial flora involved and their potential to cause ophthalmic infections. Methods: Four samples each from 50 participants (n=200) were collected from the l...

  4. 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,...

  5. 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

  6. Defect inspection of actuator lenses using swept-source optical coherence tomography

    Science.gov (United States)

    Lee, Jaeyul; Shirazi, Muhammad Faizan; Park, Kibeom; Jeon, Mansik; Kim, Jeehyun

    2017-12-01

    Actuator lens industries have gained an enormous interest with the enhancement of various latest communication devices, such as mobile phone and notebooks. The quality of the aforementioned devices can be degraded due to the internal defects of actuator lenses. Therefore, in this study, we implemented swept-source optical coherence tomography (SS-OCT) system to inspect defects of actuator lenses. Owing to the high-resolution of the SS-OCT system, defected foreign substances between the actuator lenses, defective regions of lenses and surface stains were more clearly distinguished through three-dimensional (3D) and two-dimensional (2D) cross-sectional OCT images. Therefore, the implemented SS-OCT system can be considered as a potential application to defect inspection of actuator lens.

  7. 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.

  8. 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.

  9. Power Profiles and In Vitro Optical Quality of Scleral Contact Lenses: Effect of the Aperture and Power.

    Science.gov (United States)

    Domínguez-Vicent, Alberto; Esteve-Taboada, Jose Juan; Recchioni, Alberto; Brautaset, Rune

    2017-01-13

    To assess the power profile and in vitro optical quality of scleral contact lenses with different powers as a function of the optical aperture. The mini and semiscleral contact lenses (Procornea) were measured for five powers per design. The NIMO TR-1504 (Lambda-X) was used to assess the power profile and Zernike coefficients of each contact lens. Ten measurements per lens were taken at 3- and 6-mm apertures. Furthermore, the optical quality of each lens was described in Zernike coefficients, modulation transfer function, and point spread function (PSF). A convolution of each lens PSF with an eye-chart image was also computed. The optical power fluctuated less than 0.5 diopters (D) along the optical zone of each lens. However, the optical power obtained for some lenses did not match with its corresponding nominal one, the maximum difference being 0.5 D. In optical quality, small differences were obtained among all lenses within the same design. Although significant differences were obtained among lenses (Pscleral lens. Additionally, the optical quality of both lenses has showed to be independent of the lens power within the same aperture.

  10. 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.

  11. '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 ...

  12. 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

  13. 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

  14. 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.

  15. 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.

  16. 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

  17. 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

  18. Ultraviolet radiation-blocking characteristics of contact lenses: relevance to eye protection for psoralen-sensitised patients.

    Science.gov (United States)

    Anstey, A; Taylor, D; Chalmers, I; Ansari, E

    1999-10-01

    Nine brands of contact lens marketed as "UV protective" were tested for ultraviolet (UV) transmission in order to assess potential suitability for psoralen-sensitised patients. UV-transmission characteristics of hydrated lenses was tested with a Bentham monochromator spectro-radiometer system. All lenses showed minimal transmission loss in the visible band. The performance of the nine lenses was uniform for ultraviolet B radiation with negligible transmission, but showed variation in transmission for ultraviolet A radiation. None of the lenses complied with UV-transmission criteria used previously to assess UV-blocking spectacles. Only two lenses had UV-blocking characteristics which came close to the arbitrary criteria used. The performance of ordinary soft and hard lenses was very similar, with negligible blocking of UV radiation. None of the nine contact lenses marketed as "UV protective" excluded sufficient UVA to comply with criteria in current use to assess UV protection in spectacles for psoralen-sensitised patients. However, the improved UV-blocking characteristics of contact lenses identified in this paper compared to previous studies suggests that such a contact lens will soon become available. Meanwhile, contact lens-wearing systemically sensitised PUVA patients should continue to wear approved spectacles for eye protection whilst photosensitised with psoralen.

  19. 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...

  20. 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...

  1. 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.

  2. 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...

  3. 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...

  4. 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...

  5. 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.

  6. 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.

  7. Speed of Gravitational Waves from Strongly Lensed Gravitational Waves and Electromagnetic Signals.

    Science.gov (United States)

    Fan, Xi-Long; Liao, Kai; Biesiada, Marek; Piórkowska-Kurpas, Aleksandra; Zhu, Zong-Hong

    2017-03-03

    We propose a new model-independent measurement strategy for the propagation speed of gravitational waves (GWs) based on strongly lensed GWs and their electromagnetic (EM) counterparts. This can be done in two ways: by comparing arrival times of GWs and their EM counterparts and by comparing the time delays between images seen in GWs and their EM counterparts. The lensed GW-EM event is perhaps the best way to identify an EM counterpart. Conceptually, this method does not rely on any specific theory of massive gravitons or modified gravity. Its differential setting (i.e., measuring the difference between time delays in GW and EM domains) makes it robust against lens modeling details (photons and GWs travel in the same lensing potential) and against internal time delays between GW and EM emission acts. It requires, however, that the theory of gravity is metric and predicts gravitational lensing similar to general relativity. We expect that such a test will become possible in the era of third-generation gravitational-wave detectors, when about 10 lensed GW events would be observed each year. The power of this method is mainly limited by the timing accuracy of the EM counterpart, which for kilonovae is around 10^{4}  s. This uncertainty can be suppressed by a factor of ∼10^{10}, if strongly lensed transients of much shorter duration associated with the GW event can be identified. Candidates for such short transients include short γ-ray bursts and fast radio bursts.

  8. 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.

  9. 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.

  10. Universal fluctuations in orbital diamagnetism

    Science.gov (United States)

    Pal, P. S.; Saha, Arnab; Jayannavar, A. M.

    2018-03-01

    Bohr-van Leuween theorem has attracted the notice of physicists for more than 100 years. The theorem states about the absence of magnetisation in classical systems in thermal equilibrium. In this paper, we discuss about fluctuations of magnetic moment in classical systems. In recent years, this topic has been investigated intensively and it is not free from controversy. We have considered a system consisting of a single particle moving in a plane. A magnetic field is applied perpendicular to the plane. The system is in contact with a thermal bath. We have considered three cases: (a) particle moving in a homogeneous medium, (b) particle moving in a medium with space-dependent friction and (c) particle moving in a medium with space-dependent temperature. For all the three cases, the average magnetic moment and fluctuations in magnetic moment have been calculated. Average magnetic moment saturates to a finite value in the case of free particle but goes to zero when the particle is confined by a 2D harmonic potential. Fluctuations in magnetic moment shows universal features in the presence of arbitrary friction inhomogeneity. For this case, the system reaches equilibrium asymptotically. In the case of space-dependent temperature profile, the stationary distribution is non-Gibbsian and fluctuations deviate from universal value for the bounded system only.

  11. Molecular characterization of the cold- and heat-induced Arabidopsis PXL1 gene and its potential role in transduction pathways under temperature fluctuations.

    Science.gov (United States)

    Jung, Chang Gyo; Hwang, Sun-Goo; Park, Yong Chan; Park, Hyeon Mi; Kim, Dong Sub; Park, Duck Hwan; Jang, Cheol Seong

    2015-03-15

    LRR-RLK (Leucine-Rich Repeat Receptor-Like Kinase) proteins are believed to play essential roles in cell-to-cell communication during various cellular processes including development, hormone perception, and abiotic stress responses. We isolated an LRR-RLK gene previously named Arabidopsis PHLOEM INTERCALATED WITH XYLEM-LIKE 1 (AtPXL1) and examined its expression patterns. AtPXL1 was highly induced by cold and heat stress, but not by drought. The fluorescence signal of 35S::AtPXL1-EGFP was closely localized to the plasma membrane. A yeast two-hybrid and bimolecular fluorescence complementation assay exhibited that AtPXL1 interacts with both proteins, A. thaliana histidine-rich dehydrin1 (AtHIRD1) and A. thaliana light-harvesting protein complex I (AtLHCA1). We found that AtPXL1 possesses autophosphorylation activity and phosphorylates AtHIRD1 and AtLHCA1 in an in vitro assay. Subsequently, we found that the knockout line (atpxl1) showed hypersensitive phenotypes when subjected to cold and heat during the germination stage, while the AtPXL1 overexpressing line as well as wild type plants showed high germination rates compared to the knockout plants. These results provide an insight into the molecular function of AtPXL1 in the regulation of signal transduction pathways under temperature fluctuations. Copyright © 2015 Elsevier GmbH. All rights reserved.

  12. Pervasive gene expression responses to a fluctuating diet in Drosophila melanogaster: The importance of measuring multiple traits to decouple potential mediators of life span and reproduction.

    Science.gov (United States)

    Zandveld, Jelle; van den Heuvel, Joost; Mulder, Maarten; Brakefield, Paul M; Kirkwood, Thomas B L; Shanley, Daryl P; Zwaan, Bas J

    2017-11-01

    Phenotypic plasticity is an important concept in life-history evolution, and most organisms, including Drosophila melanogaster, show a plastic life-history response to diet. However, little is known about how these life-history responses are mediated. In this study, we compared adult female flies fed an alternating diet (yoyo flies) with flies fed a constant low (CL) or high (CH) diet and tested how whole genome expression was affected by these diet regimes and how the transcriptional responses related to different life-history traits. We showed that flies were able to respond quickly to diet fluctuations throughout life span by drastically changing their transcription. Importantly, by measuring the response of multiple life-history traits we were able to decouple groups of genes associated with life span or reproduction, life-history traits that often covary with a diet change. A coexpression network analysis uncovered which genes underpin the separate and shared regulation of these life-history traits. Our study provides essential insights to help unravel the genetic architecture mediating life-history responses to diet, and it shows that the flies' whole genome transcription response is highly plastic. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

  13. Quantum fluctuations and inflation

    International Nuclear Information System (INIS)

    Bardeen, J.M.; Bublik, G.J.

    1987-01-01

    The authors study the effect of quantum fluctuations on the roll-down rate of the inflation field in a semiclassical approximation; this is done by treating the inflation field as a classical random field. The quantum fluctuations are simulated by a noise term in the equation of motion. Two different inflationary scenarios (new and chaotic inflation) are considered and it is found that the roll-down rate of the median value of the inflation field is increased by the quantum fluctuations. Non-linear effects may become important in the later stages of the inflationary regime. (author)

  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. Fully Quantum Fluctuation Theorems

    Science.gov (United States)

    Åberg, Johan

    2018-02-01

    Systems that are driven out of thermal equilibrium typically dissipate random quantities of energy on microscopic scales. Crooks fluctuation theorem relates the distribution of these random work costs to the corresponding distribution for the reverse process. By an analysis that explicitly incorporates the energy reservoir that donates the energy and the control system that implements the dynamic, we obtain a quantum generalization of Crooks theorem that not only includes the energy changes in the reservoir but also the full description of its evolution, including coherences. Moreover, this approach opens up the possibility for generalizations of the concept of fluctuation relations. Here, we introduce "conditional" fluctuation relations that are applicable to nonequilibrium systems, as well as approximate fluctuation relations that allow for the analysis of autonomous evolution generated by global time-independent Hamiltonians. We furthermore extend these notions to Markovian master equations, implicitly modeling the influence of the heat bath.

  17. Fully Quantum Fluctuation Theorems

    Directory of Open Access Journals (Sweden)

    Johan Åberg

    2018-02-01

    Full Text Available Systems that are driven out of thermal equilibrium typically dissipate random quantities of energy on microscopic scales. Crooks fluctuation theorem relates the distribution of these random work costs to the corresponding distribution for the reverse process. By an analysis that explicitly incorporates the energy reservoir that donates the energy and the control system that implements the dynamic, we obtain a quantum generalization of Crooks theorem that not only includes the energy changes in the reservoir but also the full description of its evolution, including coherences. Moreover, this approach opens up the possibility for generalizations of the concept of fluctuation relations. Here, we introduce “conditional” fluctuation relations that are applicable to nonequilibrium systems, as well as approximate fluctuation relations that allow for the analysis of autonomous evolution generated by global time-independent Hamiltonians. We furthermore extend these notions to Markovian master equations, implicitly modeling the influence of the heat bath.

  18. Fishing and stock fluctuations

    National Research Council Canada - National Science Library

    Laevastu, Taivo; Favorite, F

    1988-01-01

    .... Scarcely publicized are the multitude of causes of fish stock fluctuations. This book attempts to summarize the available knowledge on the subject and includes original work of the authors on a matter vital to the fisheries industries of the world...

  19. 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.

  20. 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

  1. Polymer X-ray refractive nano-lenses fabricated by additive technology.

    Science.gov (United States)

    Petrov, A K; Bessonov, V O; Abrashitova, K A; Kokareva, N G; Safronov, K R; Barannikov, A A; Ershov, P A; Klimova, N B; Lyatun, I I; Yunkin, V A; Polikarpov, M; Snigireva, I; Fedyanin, A A; Snigirev, A

    2017-06-26

    The present work demonstrates the potential applicability of additive manufacturing to X-Ray refractive nano-lenses. A compound refractive lens with a radius of 5 µm was produced by the two-photon polymerization induced lithography. It was successfully tested at the X-ray microfocus laboratory source and a focal spot of 5 μm was measured. An amorphous nature of polymer material combined with the potential of additive technologies may result in a significantly enhanced focusing performance compared to the best examples of modern X-ray compound refractive lenses.

  2. Scaling metabolic rate fluctuations

    OpenAIRE

    Labra, Fabio A.; Marquet, Pablo A.; Bozinovic, Francisco

    2007-01-01

    Complex ecological and economic systems show fluctuations in macroscopic quantities such as exchange rates, size of companies or populations that follow non-Gaussian tent-shaped probability distributions of growth rates with power-law decay, which suggests that fluctuations in complex systems may be governed by universal mechanisms, independent of particular details and idiosyncrasies. We propose here that metabolic rate within individual organisms may be considered as an example of an emerge...

  3. 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

  4. Evidence for the potential influence of chemocline fluctuations on the Frasnian-Famennian Biotic Crisis in the Illinois and Appalachian Basins

    Science.gov (United States)

    Uveges, B. T.; Junium, C. K.; Boyer, D.; Cohen, P.; Day, J. E.

    2017-12-01

    the KWEs, and thus the FFBC, were the result of exacerbated chemocline fluctuations already inherent to the basin system. The resultant influx of low oxygen, high nutrient water would have not only placed stress on shallow water organisms, but may have also induced eutrophication through spurred primary productivity of organic matter, compounding the the severity of the event.

  5. The Protective Effect of Brown-, Gray-, and Blue-Tinted Lenses against Blue LED Light-Induced Cell Death in A2E-Laden Human Retinal Pigment Epithelial Cells.

    Science.gov (United States)

    Park, Sang-Il; Jang, Young Pyo

    2017-01-01

    A2E-laden ARPE-19 cells were exposed to a blue light to induce cytotoxicity, in order to investigate the protective effects of various tinted ophthalmic lenses against photo-induced cytotoxicity in human retinal pigment epithelial (RPE) cells laden with A2E, known to be among the etiologies of age-related macular degeneration (AMD). Different-colored tinted lenses with varying levels of tint and different filtering characteristics, such as polarized, blue-cut, and photochromatic lenses, were placed over the cells, and the protective efficacies thereof were evaluated by lactate dehydrogenase assay. When tinted lenses were placed over ARPE-19 cells, there were different reductions in cytotoxicity according to the colors and tint levels. The level of protection afforded by brown-tinted lenses was 6.9, 36.1, and 49% with a tint level of 15, 50, and 80%, respectively. For gray-tinted lenses, the protective effect was 16.3, 35, and 43.4% for the corresponding degree of tint, respectively. In the case of blue-tinted lenses, a protective effect of 20% was observed with 80% tinted lenses, but 15 and 50% tinted lenses provided no significant protection. In addition, photochromic lenses showed a protective effect but blue-cut lenses and polarized lenses provided no significant protection. Tinted lenses significantly reduced cytotoxicity in RPE cells irradiated with blue light. The protection was more efficient in lenses with a brown or gray tint than in blue-tinted lenses. Tinted glasses may provide significant protection against potential blue-light-induced photochemical and photo-oxidative damage in RPE cells. © 2016 S. Karger AG, Basel.

  6. 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.

  7. 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.

  8. 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...

  9. 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.

  10. Simulations for 21 cm radiation lensing at EoR redshifts

    Science.gov (United States)

    Romeo, Alessandro; Metcalf, Robert Benton; Pourtsidou, Alkistis

    2018-02-01

    We introduce simulations aimed at assessing how well weak gravitational lensing of 21cm radiation from the Epoch of Reionization (z ˜ 8) can be measured by a Square Kilometre Array (SKA)-like radio telescope. A simulation pipeline has been implemented to study the performance of lensing reconstruction techniques. We show how well the lensing signal can be reconstructed using the 3D quadratic lensing estimator in Fourier space assuming different survey strategies. The numerical code introduced in this work is capable of dealing with issues that cannot be treated analytically such as the discreteness of visibility measurements and the inclusion of a realistic model for the antennas distribution. This paves the way for future numerical studies implementing more realistic re-ionization models, foreground subtraction schemes, and testing the performance of lensing estimators that take into account the non-Gaussian distribution of HI after re-ionization. If multiple frequency channels covering z ˜ 7-11.6 are combined, Phase 1 of SKA-Low should be able to obtain good quality images of the lensing potential with a total resolution of ˜1.6 arcmin. The SKA-Low Phase 2 should be capable of providing images with high fidelity even using data from z ˜ 7.7 to 8.3. We perform tests aimed at evaluating the numerical implementation of the mapping reconstruction. We also discuss the possibility of measuring an accurate lensing power spectrum. Combining data from z ˜ 7 to 11.6 using the SKA2-Low telescope model, we find constraints comparable to sample variance in the range L < 1000, even for survey areas as small as 25 deg2.

  11. Temperature changes in contact lenses in connection with radiation from welding arcs.

    Science.gov (United States)

    Lövsund, P; Nilsson, S E; Lindh, H; Oberg, P A

    1979-09-01

    Because of reports of risks associated with the use of contact lenses during exposure to welding arcs, the temperature changes in soft contact lenses were recorded in connection with certain types of welding [manual metal arc (MMA) welding, tungsten inert-gas (TIG) welding, and metal inert-gas (MIG) welding], both with free-hanging lenses and lenses applied to the eyes of anesthetized rabbits. A great increase in temperature was noted, especially with MMA welding. At a distance of 0.4 m the temperature of a lens on a rabbit eye rose from about 35 to 50 degrees C within 6 min, whereas the air temperature only increased from 23 to 30 degrees C. The increase was the greatest at the beginning of the welding period. Most of the lenses completely dried out during the experiment, and there would seem to be a potential risk that the lens would adhere to the cornea. One safety glass screen (DIN 10 A) proved effective in preventing the rise in temperature in contact lenses during MMA welding. Even though it is impossible to direct the eyes at the arc for a prolonged period of time, the use of contact lenses in connection with at least certain types of welding is not to be recommended without the use of a suitable safety glass screen (or safety glasses). With regard to the large number of particles in the welding environment, also a risk factor for contact lens wearers, it is doubtful whether even safety glasses or screens are satisfactory unless they fit closely.

  12. Edge fluctuations in the MST [Madison Symmetric Torus] reversed field pinch

    International Nuclear Information System (INIS)

    Almagri, A.; Assadi, S.; Beckstead, J.; Chartas, G.; Crocker, N.; Den Hartog, D.; Dexter, R.; Hokin, S.; Holly, D.; Nilles, E.; Prager, S.; Rempel, T.; Sarff, J.; Scime, E.; Shen, W.; Spragins, C.; Sprott, J.; Starr, G.; Stoneking, M.; Watts, C.

    1990-10-01

    Edge magnetic and electrostatic fluctuations are measured in the Madison Symmetric Torus (MST) reversed field pinch. At low frequency ( e > p e /p e where φ and p e are the fluctuating potential and pressure, respectively). From measurements of the fluctuating density, temperature, and potential we infer that the electrostatic fluctuation induced transport of particles and energy can be substantial. 13 refs., 11 figs

  13. 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.

  14. 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.

  15. 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.

  16. 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...

  17. 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....

  18. Heat fluctuations and initial ensembles

    Science.gov (United States)

    Kim, Kwangmoo; Kwon, Chulan; Park, Hyunggyu

    2014-09-01

    Time-integrated quantities such as work and heat increase incessantly in time during nonequilibrium processes near steady states. In the long-time limit, the average values of work and heat become asymptotically equivalent to each other, since they only differ by a finite energy change in average. However, the fluctuation theorem (FT) for the heat is found not to hold with the equilibrium initial ensemble, while the FT for the work holds. This reveals an intriguing effect of everlasting initial memory stored in rare events. We revisit the problem of a Brownian particle in a harmonic potential dragged with a constant velocity, which is in contact with a thermal reservoir. The heat and work fluctuations are investigated with initial Boltzmann ensembles at temperatures generally different from the reservoir temperature. We find that, in the infinite-time limit, the FT for the work is fully recovered for arbitrary initial temperatures, while the heat fluctuations significantly deviate from the FT characteristics except for the infinite initial-temperature limit (a uniform initial ensemble). Furthermore, we succeed in calculating finite-time corrections to the heat and work distributions analytically, using the modified saddle point integral method recently developed by us. Interestingly, we find noncommutativity between the infinite-time limit and the infinite-initial-temperature limit for the probability distribution function (PDF) of the heat.

  19. Reconstruction of an Non-Monochromatically Illuminated Object Imaged through an Electron Microscope with a Fluctuating Electromagnetic Field

    NARCIS (Netherlands)

    Hoenders, B.J.

    1975-01-01

    It is shown that a weak phase object imaged by an electron microscope within the presence of instabilities of the lense currents and the acceleration voltage, fluctuating electromagnetic field, can be reconstructed from the intensity distribution in the image plane. Perfectly incoherent illumination

  20. A Robust Mass Estimator for Dark Matter Subhalo Perturbations in Strong Gravitational Lenses

    Energy Technology Data Exchange (ETDEWEB)

    Minor, Quinn E. [Department of Science, Borough of Manhattan Community College, City University of New York, New York, NY 10007 (United States); Kaplinghat, Manoj [Department of Physics and Astronomy, University of California, Irvine CA 92697 (United States); Li, Nan [Department of Astronomy and Astrophysics, The University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States)

    2017-08-20

    A few dark matter substructures have recently been detected in strong gravitational lenses through their perturbations of highly magnified images. We derive a characteristic scale for lensing perturbations and show that they are significantly larger than the perturber’s Einstein radius. We show that the perturber’s projected mass enclosed within this radius, scaled by the log-slope of the host galaxy’s density profile, can be robustly inferred even if the inferred density profile and tidal radius of the perturber are biased. We demonstrate the validity of our analytic derivation using several gravitational lens simulations where the tidal radii and the inner log-slopes of the density profile of the perturbing subhalo are allowed to vary. By modeling these simulated data, we find that our mass estimator, which we call the effective subhalo lensing mass, is accurate to within about 10% or smaller in each case, whereas the inferred total subhalo mass can potentially be biased by nearly an order of magnitude. We therefore recommend that the effective subhalo lensing mass be reported in future lensing reconstructions, as this will allow for a more accurate comparison with the results of dark matter simulations.

  1. Ultraviolet absorption by contact lenses and the significance on the ocular anterior segment.

    Science.gov (United States)

    Chandler, Heather

    2011-07-01

    It is well established that both acute and chronic ultraviolet (UV) exposure can lead to various ophthalmic pathologic conditions in the anterior segment. Several scientific studies have demonstrated that after UV exposure, the unprotected cornea is vulnerable to damage in the epithelial, stromal, and endothelial cellular layers. DNA damage, apoptosis, and altered protease expression are all examples of harmful changes that can occur within the cornea after irradiation. Beyond the cornea, damage associated with UV exposure, such as decreased antioxidant levels and increased reactive oxygen species production, has been noted in the aqueous humor and crystalline lens. Ultraviolet-blocking contact lenses have the potential to provide protection against such exposure to harmful UV radiation. Experimental use of UV-absorbing contact lenses prevented detrimental cellular changes to the cornea and maintained corneal clarity after UV exposure. Additionally, studies suggest that shielding the aqueous humor and crystalline lens from irradiation with UV-absorbing contact lenses aids in protection against precataractous changes. Despite ongoing research, to date, neither chronic nor clinical studies have been performed in humans to demonstrate that wearing UV-blocking contact lenses reduces the risk of developing cataracts or other ocular disorders within the anterior segment. This article will discuss the impact of UV exposure on ocular tissue and the need for adequate UV protection, with particular emphasis on UV-blocking contact lenses.

  2. 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.)

  3. 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.)

  4. MUSE spectroscopy and deep observations of a unique compact JWST target, lensing cluster CLIO

    Science.gov (United States)

    Griffiths, Alex; Conselice, Christopher J.; Alpaslan, Mehmet; Frye, Brenda L.; Diego, Jose M.; Zitrin, Adi; Yan, Haojing; Ma, Zhiyuan; Barone-Nugent, Robert; Bhatawdekar, Rachana; Driver, Simon P.; Robotham, Aaron S. G.; Windhorst, Rogier A.; Wyithe, J. Stuart B.

    2018-04-01

    We present the results of a VLT MUSE/FORS2 and Spitzer survey of a unique compact lensing cluster CLIO at z = 0.42, discovered through the GAMA survey using spectroscopic redshifts. Compact and massive clusters such as this are understudied, but provide a unique prospective on dark matter distributions and for finding background lensed high-z galaxies. The CLIO cluster was identified for follow-up observations due to its almost unique combination of high-mass and dark matter halo concentration, as well as having observed lensing arcs from ground-based images. Using dual band optical and infra-red imaging from FORS2 and Spitzer, in combination with MUSE optical spectroscopy we identify 89 cluster members and find background sources out to z = 6.49. We describe the physical state of this cluster, finding a strong correlation between environment and galaxy spectral type. Under the assumption of an NFW profile, we measure the total mass of CLIO to be M200 = (4.49 ± 0.25) × 1014 M⊙. We build and present an initial strong-lensing model for this cluster, and measure a relatively low intracluster light (ICL) fraction of 7.21 ± 1.53 per cent through galaxy profile fitting. Due to its strong potential for lensing background galaxies and its low ICL, the CLIO cluster will be a target for our 110 h James Webb Space Telescope `Webb Medium-Deep Field' (WMDF) GTO program.

  5. Universal mesoscopic conductance fluctuations

    International Nuclear Information System (INIS)

    Evangelou, S.N.

    1992-01-01

    The theory of conductance fluctuations in disordered metallic systems with size large compared to the mean free path of the electron but small compared to localization length is considered. It is demonstrates that fluctuations have an universal character and are due to repulsion between levels and spectral rigidity. The basic fluctuation measures for the energy spectrum in the mesoscopic regime of disordered systems are consistent with the Gaussian random matrix ensemble predictions. Although our disordered electron random matrix ensemble does not belong to the Gaussian ensemble the two ensembles turn out to be essentially similar. The level repulsion and the spectral rigidity found in nuclear spectra should also be observed in the metallic regime of Anderson localization. 7 refs. (orig.)

  6. Spin fluctuations and the

    Directory of Open Access Journals (Sweden)

    V.M. Loktev

    2008-09-01

    Full Text Available We analyze the spectral properties of a phenomenological model for a weakly doped two-dimensional antiferromagnet, in which the carriers move within one of the two sublattices where they were introduced. Such a constraint results in the free carrier spectra with the maxima at k=(± π/2 , ± π/2 observed in some cuprates. We consider the spectral properties of the model by taking into account fluctuations of the spins in the antiferromagnetic background. We show that such fluctuations lead to a non-pole-like structure of the single-hole Green's function and these fluctuations can be responsible for some anomalous "strange metal" properties of underdoped cuprates in the nonsuperconducting regime.

  7. The fluctuating gap model

    International Nuclear Information System (INIS)

    Cao, Xiaobin

    2011-01-01

    The quasi-one-dimensional systems exhibit some unusual phenomenon, such as the Peierls instability, the pseudogap phenomena and the absence of a Fermi-Dirac distribution function line shape in the photoemission spectroscopy. Ever since the discovery of materials with highly anisotropic properties, it has been recognized that fluctuations play an important role above the three-dimensional phase transition. This regime where the precursor fluctuations are presented can be described by the so called fluctuating gap model (FGM) which was derived from the Froehlich Hamiltonian to study the low energy physics of the one-dimensional electron-phonon system. Not only is the FGM of great interest in the context of quasi-one-dimensional materials, liquid metal and spin waves above T c in ferromagnets, but also in the semiclassical approximation of superconductivity, it is possible to replace the original three-dimensional problem by a directional average over effectively one-dimensional problem which in the weak coupling limit is described by the FGM. In this work, we investigate the FGM in a wide temperature range with different statistics of the order parameter fluctuations. We derive a formally exact solution to this problem and calculate the density of states, the spectral function and the optical conductivity. In our calculation, we show that a Dyson singularity appears in the low energy density of states for Gaussian fluctuations in the commensurate case. In the incommensurate case, there is no such kind of singularity, and the zero frequency density of states varies differently as a function of the correlation lengths for different statistics of the order parameter fluctuations. Using the density of states we calculated with non-Gaussian order parameter fluctuations, we are able to calculate the static spin susceptibility which agrees with the experimental data very well. In the calculation of the spectral functions, we show that as the correlation increases, the quasi

  8. The fluctuating gap model

    Energy Technology Data Exchange (ETDEWEB)

    Cao, Xiaobin

    2011-01-15

    The quasi-one-dimensional systems exhibit some unusual phenomenon, such as the Peierls instability, the pseudogap phenomena and the absence of a Fermi-Dirac distribution function line shape in the photoemission spectroscopy. Ever since the discovery of materials with highly anisotropic properties, it has been recognized that fluctuations play an important role above the three-dimensional phase transition. This regime where the precursor fluctuations are presented can be described by the so called fluctuating gap model (FGM) which was derived from the Froehlich Hamiltonian to study the low energy physics of the one-dimensional electron-phonon system. Not only is the FGM of great interest in the context of quasi-one-dimensional materials, liquid metal and spin waves above T{sub c} in ferromagnets, but also in the semiclassical approximation of superconductivity, it is possible to replace the original three-dimensional problem by a directional average over effectively one-dimensional problem which in the weak coupling limit is described by the FGM. In this work, we investigate the FGM in a wide temperature range with different statistics of the order parameter fluctuations. We derive a formally exact solution to this problem and calculate the density of states, the spectral function and the optical conductivity. In our calculation, we show that a Dyson singularity appears in the low energy density of states for Gaussian fluctuations in the commensurate case. In the incommensurate case, there is no such kind of singularity, and the zero frequency density of states varies differently as a function of the correlation lengths for different statistics of the order parameter fluctuations. Using the density of states we calculated with non-Gaussian order parameter fluctuations, we are able to calculate the static spin susceptibility which agrees with the experimental data very well. In the calculation of the spectral functions, we show that as the correlation increases, the

  9. 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

  10. 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

  11. 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...

  12. 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,

  13. 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

  14. 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

  15. 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.

  16. Effective wavefront aberration measurement of spectacle lenses in as-worn status

    Science.gov (United States)

    Jia, Zhigang; Xu, Kai; Fang, Fengzhou

    2018-04-01

    An effective wavefront aberration analysis method for measuring spectacle lenses in as-worn status was proposed and verified using an experimental apparatus based on an eye rotation model. Two strategies were employed to improve the accuracy of measurement of the effective wavefront aberrations on the corneal sphere. The influences of three as-worn parameters, the vertex distance, pantoscopic angle, and face form angle, together with the eye rotation and corresponding incident beams, were objectively and quantitatively obtained. The experimental measurements of spherical single vision and freeform progressive addition lenses demonstrate the accuracy and validity of the proposed method and experimental apparatus, which provide a potential means of achieving supernormal vision correction with customization and personalization in optimizing the as-worn status-based design of spectacle lenses and evaluating their manufacturing and imaging qualities.

  17. Mass Models and Environment of the New Quadruply Lensed Quasar SDSS J1330+1810

    Energy Technology Data Exchange (ETDEWEB)

    Oguri, Masamune; Inada, Naohisa; Blackburne, Jeffrey A.; Shin, Min-Su; Kayo, Issha; Strauss, Michael A.; Schneider, Donald P.; York, Donald G.

    2008-09-09

    We present the discovery of a new quadruply lensed quasar. The lens system, SDSS J1330+1810 at z{sub s} = 1.393, was identified as a lens candidate from the spectroscopic sample of the Sloan Digital Sky Survey. Optical and near-infrared images clearly show four quasar images with a maximum image separation of 1.76 inch, as well as a bright lensing galaxy. We measure a redshift of the lensing galaxy of z{sub 1} = 0.373 from absorption features in the spectrum. We find a foreground group of galaxies at z = 0.31 centred {approx} 120 inch southwest of the lens system. Simple mass models fit the data quite well, including the flux ratios between images, although the lens galaxy appears to be {approx} 1 mag brighter than expected by the Faber-Jackson relation. Our mass modeling suggests that shear from nearby structure is affecting the lens potential.

  18. 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

  19. 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.

  20. 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.

  1. Galaxy-galaxy weak gravitational lensing in f(R) gravity

    Science.gov (United States)

    Li, Baojiu; Shirasaki, Masato

    2018-03-01

    We present an analysis of galaxy-galaxy weak gravitational lensing (GGL) in chameleon f(R) gravity - a leading candidate of non-standard gravity models. For the analysis, we have created mock galaxy catalogues based on dark matter haloes from two sets of numerical simulations, using a halo occupation distribution (HOD) prescription which allows a redshift dependence of galaxy number density. To make a fairer comparison between the f(R) and Λ cold dark matter (ΛCDM) models, their HOD parameters are tuned so that the galaxy two-point correlation functions in real space (and therefore the projected two-point correlation functions) match. While the f(R) model predicts an enhancement of the convergence power spectrum by up to ˜ 30 per cent compared to the standard ΛCDM model with the same parameters, the maximum enhancement of GGL is only half as large and less than 5 per cent on separations above ˜1-2 h-1 Mpc, because the latter is a cross-correlation of shear (or matter, which is more strongly affected by modified gravity) and galaxy (which is weakly affected given the good match between galaxy autocorrelations in the two models) fields. We also study the possibility of reconstructing the matter power spectrum by combination of GGL and galaxy clustering in f(R) gravity. We find that the galaxy-matter cross-correlation coefficient remains at unity down to ˜2-3 h-1 Mpc at relevant redshifts even in f(R) gravity, indicating joint analysis of GGL and galaxy clustering can be a powerful probe of matter density fluctuations in chameleon gravity. The scale dependence of the model differences in their predictions of GGL can potentially allows us to break the degeneracy between f(R) gravity and other cosmological parameters such as Ωm and σ8.

  2. Dark Energy Survey Year 1 Results: Methodology and Projections for Joint Analysis of Galaxy Clustering, Galaxy Lensing, and CMB Lensing Two-point Functions

    Energy Technology Data Exchange (ETDEWEB)

    Giannantonio, T.; et al.

    2018-02-14

    Optical imaging surveys measure both the galaxy density and the gravitational lensing-induced shear fields across the sky. Recently, the Dark Energy Survey (DES) collaboration used a joint fit to two-point correlations between these observables to place tight constraints on cosmology (DES Collaboration et al. 2017). In this work, we develop the methodology to extend the DES Collaboration et al. (2017) analysis to include cross-correlations of the optical survey observables with gravitational lensing of the cosmic microwave background (CMB) as measured by the South Pole Telescope (SPT) and Planck. Using simulated analyses, we show how the resulting set of five two-point functions increases the robustness of the cosmological constraints to systematic errors in galaxy lensing shear calibration. Additionally, we show that contamination of the SPT+Planck CMB lensing map by the thermal Sunyaev-Zel'dovich effect is a potentially large source of systematic error for two-point function analyses, but show that it can be reduced to acceptable levels in our analysis by masking clusters of galaxies and imposing angular scale cuts on the two-point functions. The methodology developed here will be applied to the analysis of data from the DES, the SPT, and Planck in a companion work.

  3. Origin of density fluctuations in extended inflation

    International Nuclear Information System (INIS)

    Kolb, E.W.; Salopek, D.S.; Turner, M.S.

    1990-01-01

    We calculate both the curvature and isocurvature density fluctuations that arise due to quantum fluctuations in a simple model of extended inflation based upon the Jordan-Brans-Dicke theory. The curvature fluctuations that arise due to quantum fluctuations in the Brans-Dicke field in general have a non-scale-invariant spectrum and an amplitude that is cosmologically acceptable and interesting without having to tune any coupling constant to a very small value. The curvature perturbations that arise due to the Higgs field are subdominant. If there are other massless fields in the theory, e.g., an axion or an ilion, then isocurvature fluctuations arise in these fields too. Production of gravitational waves and the massless particles associated with excitations of the Brans-Dicke field are also discussed. Several attempts at more realistic models of extended inflation are also analyzed. The importance of the Einstein conformal frame in calculating curvature fluctuations is emphasized. When viewed in this frame, extended inflation closely resembles slow-rollover inflation with an exponential potential, and the usual formula for the amplitude of curvature perturbations applies directly

  4. Origin of density fluctuations in extended inflation

    International Nuclear Information System (INIS)

    Kolb, E.W.; Salopek, D.S.; Turner, M.S.

    1990-05-01

    The density fluctuations (both curvature and isocurvature) that arise due to quantum fluctuations in a simple model of extended inflation based upon the Jordan-Brans-Dicke theory are calculated. Curvature fluctuations arise due to quantum fluctuations in the Brans-Dicke field, in general have a nonscale-invariant spectrum, and can have an amplitude that is cosmologically acceptable and interesting without having to tune any coupling constant to a very small value. The density perturbations that arise due to the inflation field are subdominant. If there are other massless fields in the theory, e.g., an axion or an ilion, then isocurvature fluctuations arise in these fields too. Production of gravitational waves and the massless particles associated with excitations of the Brans-Dicke field are also discussed. Several attempts at more realistic models of extended inflation are also analyzed. The importance of the Einstein conformal frame in calculating curvature fluctuations is emphasized. When viewed in this frame, extended inflation closely resembles slow-rollover inflation with an exponential potential and the usual formula for the amplitude of curvature perturbations applies

  5. Fluctuations in quantum devices

    Directory of Open Access Journals (Sweden)

    H.Haken

    2004-01-01

    Full Text Available Logical gates can be formalized by Boolean algebra whose elementary operations can be realized by devices that employ the interactions of macroscopic numbers of elementary excitations such as electrons, holes, photons etc. With increasing miniaturization to the nano scale and below, quantum fluctuations become important and can no longer be ignored. Based on Heisenberg equations of motion for the creation and annihilation operators of elementary excitations, I determine the noise sources of composite quantum systems.

  6. Physics of fashion fluctuations

    Science.gov (United States)

    Donangelo, R.; Hansen, A.; Sneppen, K.; Souza, S. R.

    2000-12-01

    We consider a market where many agents trade different types of products with each other. We model development of collective modes in this market, and quantify these by fluctuations that scale with time with a Hurst exponent of about 0.7. We demonstrate that individual products in the model occasionally become globally accepted means of exchange, and simultaneously become very actively traded. Thus collective features similar to money spontaneously emerge, without any a priori reason.

  7. Simulation of imperfections in plastic lenses - transferring local refractive index changes into surface shape modifications

    Science.gov (United States)

    Arasa, Josep; Pizarro, Carles; Blanco, Patricia

    2016-06-01

    Injection molded plastic lenses have continuously improved their performance regarding optical quality and nowadays are as usual as glass lenses in image forming devices. However, during the manufacturing process unavoidable fluctuations in material density occur, resulting in local changes in the distribution of refractive index, which degrade the imaging properties of the polymer lens. Such material density fluctuations correlate to phase delays, which opens a path for their mapping. However, it is difficult to transfer the measured variations in refractive index into conventional optical simulation tool. Thus, we propose a method to convert the local variations in refractive index into local changes of one surface of the lens, which can then be described as a free-form surface, easy to introduce in conventional simulation tools. The proposed method was tested on a commercial gradient index (GRIN) lens for a set of six different object positions, using the MTF sagittal and tangential cuts to compare the differences between the real lens and a lens with homogenous refractive index, and the last surface converted into a free-form shape containing the internal refractive index changes. The same procedure was used to reproduce the local refractive index changes of an injected plastic lens with local index changes measured using an in-house built polariscopic arrangement, showing the capability of the method to provide successful results.

  8. 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

  9. 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.

  10. 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...

  11. 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.

  12. 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.

  13. 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.)

  14. 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)

  15. 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)

  16. 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...

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. Strain fluctuations and elastic constants

    Energy Technology Data Exchange (ETDEWEB)

    Parrinello, M.; Rahman, A.

    1982-03-01

    It is shown that the elastic strain fluctuations are a direct measure of elastic compliances in a general anisotropic medium; depending on the ensemble in which the fluctuation is measured either the isothermal or the adiabatic compliances are obtained. These fluctuations can now be calculated in a constant enthalpy and pressure, and hence, constant entropy, ensemble due to recent develpments in the molecular dynamics techniques. A calculation for a Ni single crystal under uniform uniaxial 100 tensile or compressive load is presented as an illustration of the relationships derived between various strain fluctuations and the elastic modulii. The Born stability criteria and the behavior of strain fluctuations are shown to be related.

  3. Gambling with Superconducting Fluctuations

    Science.gov (United States)

    Foltyn, Marek; Zgirski, Maciej

    2015-08-01

    Josephson junctions and superconducting nanowires, when biased close to superconducting critical current, can switch to a nonzero voltage state by thermal or quantum fluctuations. The process is understood as an escape of a Brownian particle from a metastable state. Since this effect is fully stochastic, we propose to use it for generating random numbers. We present protocol for obtaining random numbers and test the experimentally harvested data for their fidelity. Our work is prerequisite for using the Josephson junction as a tool for stochastic (probabilistic) determination of physical parameters such as magnetic flux, temperature, and current.

  4. [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.

  5. 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...

  6. 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.

  7. Universal conductance fluctuations in disordered metals

    International Nuclear Information System (INIS)

    Lee, P.A.

    1987-01-01

    The author argues that observed and theoretical fluctuations in the electrical conductance of disordered metals, induced by variations in the magnetic field or the chemical potential, are not time-dependent noise but that the conductance is a deterministic albeit fluctuating function for a given realization of the impurity configuration. A method is constructed for representing the sensitivity of the conductance of a given metal to a small change in the impurity configuration as a function of such variables as sample size, impurities per unit volume, and mean free path. The sensitivity helps explain the size of 1/f noise due to defect motion in disordered metals

  8. Edge plasma fluctuations measurements in fusion experiments

    International Nuclear Information System (INIS)

    Schrittwieser, R.; Ionitha, C.; Balan, P.C.; Varandas, C.A.F.; Figueiredo, H.F.C.; Silva, C.; Stoeckel, J.; Adamek, J.; Hron, M.; Tichy, M.; Hidalgo, C.; Pedrosa, M.A.; Calderon, E.; Martines, E.; Van Oost, G.; Rasmussen, J.J.; Naulin, V.

    2005-01-01

    We report on investigations on electrostatic fluctuations in the edge plasma region which have been carried out during the last few years at several European fusion experiments. Various methods and probe arrangements have been used to determine fluctuations of the plasma potential, the electric field and the electron temperature. Investigations were under-taken in ISTTOK (Instituto Superior Tecnico TOKamak), Lisbon, Portugal, in CASTOR (Czech Academy of Science TORus), Prague, Czech Republic, and the TJ-II Flexible Heliac at CIEMAT in Madrid, Spain. (author)

  9. 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.

  10. 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.

  11. Differential adherence of Acanthamoeba to contact lenses: effects of material characteristics.

    Science.gov (United States)

    Seal, D V; Bennett, E S; McFadyen, A K; Todd, E; Tomlinson, A

    1995-01-01

    Acanthamoeba-associated keratitis occurs most often in contact lens wearers. The contact lens material may affect its ability to act as a mechanical vector, permitting transfer of viable amoebae from the storage case to the corneal surface. The purpose of this study was to investigate the effects of ionicity and water content on the comparative quantitative adherence of Acanthamoeba trophozoites and cysts to new, unworn hydrogel contact lenses and rigid gas-permeable contact lens materials. Sixteen quarter segments of each of 8 types of unworn hydrogel lenses representative of FDA groups 1 to 4 were exposed to freshly prepared cultures of either trophozoites or cysts of A. castellanii or A. polyphaga for 1.5 h, and then washed. Three types of rigid lens button were similarly exposed to A. castellanii trophozoites or cysts. Adherent trophozoites and cysts were then enumerated. All hydrogel lenses showed binding of both trophozoites and cysts, with the former predominating in every case. It was primarily the ionic nature of a lens surface and secondly its water content that was associated with increased quantitative adherence of Acanthamoeba. Neither form of the amoebae bound to any of the hard lens buttons. Greater relative potential exists for contamination of ionic and high-water content hydrogels by Acanthamoeba. This combination may influence mechanical transmission of the protozoon to the corneal surface. Adherence to hard lenses (as buttons) did not occur if a postincubation wash step was performed.

  12. Diffusion-Based Design of Multi-Layered Ophthalmic Lenses for Controlled Drug Release.

    Science.gov (United States)

    Pimenta, Andreia F R; Serro, Ana Paula; Paradiso, Patrizia; Saramago, Benilde; Colaço, Rogério

    2016-01-01

    The study of ocular drug delivery systems has been one of the most covered topics in drug delivery research. One potential drug carrier solution is the use of materials that are already commercially available in ophthalmic lenses for the correction of refractive errors. In this study, we present a diffusion-based mathematical model in which the parameters can be adjusted based on experimental results obtained under controlled conditions. The model allows for the design of multi-layered therapeutic ophthalmic lenses for controlled drug delivery. We show that the proper combination of materials with adequate drug diffusion coefficients, thicknesses and interfacial transport characteristics allows for the control of the delivery of drugs from multi-layered ophthalmic lenses, such that drug bursts can be minimized, and the release time can be maximized. As far as we know, this combination of a mathematical modelling approach with experimental validation of non-constant activity source lamellar structures, made of layers of different materials, accounting for the interface resistance to the drug diffusion, is a novel approach to the design of drug loaded multi-layered contact lenses.

  13. The Atacama Cosmology Telescope: Cross-Correlation of Cosmic Microwave Background Lensing and Quasars

    Science.gov (United States)

    Sherwin, Blake D; Das, Sudeep; Haijian, Amir; Addison, Graeme; Bond, Richard; Crichton, Devin; Devlin, Mark J.; Dunkley, Joanna; Gralla, Megan B.; Halpern, Mark; hide

    2012-01-01

    We measure the cross-correlation of Atacama cosmology telescope cosmic microwave background (CMB) lensing convergence maps with quasar maps made from the Sloan Digital Sky Survey DR8 SDSS-XDQSO photometric catalog. The CMB lensing quasar cross-power spectrum is detected for the first time at a significance of 3.8 sigma, which directly confirms that the quasar distribution traces the mass distribution at high redshifts z > 1. Our detection passes a number of null tests and systematic checks. Using this cross-power spectrum, we measure the amplitude of the linear quasar bias assuming a template for its redshift dependence, and find the amplitude to be consistent with an earlier measurement from clustering; at redshift z ap 1.4, the peak of the distribution of quasars in our maps, our measurement corresponds to a bias of b = 2.5 +/- 0.6. With the signal-to-noise ratio on CMB lensing measurements likely to improve by an order of magnitude over the next few years, our results demonstrate the potential of CMB lensing crosscorrelations to probe astrophysics at high redshifts.

  14. Broadband unidirectional cloaks based on flat metasurface focusing lenses

    Science.gov (United States)

    Li, Yongfeng; Zhang, Jieqiu; Qu, Shaobo; Wang, Jiafu; Pang, Yongqiang; Xu, Zhuo; Zhang, Anxue

    2015-08-01

    Bandwidth extension and thickness reduction are now the two key issues of cloaks. In this paper, we propose to achieve broadband, thin uni-directional electromagnetic (EM) cloaks using metasurfaces. To this end, a wideband flat focusing lens is firstly devised based on high-efficiency transmissive metasurfaces. Due to the nearly dispersionless parabolic phase profile along the metasurface in the operating band, incident plane waves can be focused efficiently after passing through the metasurface. Broadband unidirectional EM cloaks were then designed by combining two identical flat lenses. Upon illumination, the incident plane waves are firstly focused by one lens and then are restored by the other lens, avoiding the cloaked region. Both simulation and experiment results verify the broadband unidirectional cloak. The broad bandwidth and small thickness of such cloaks have potential applications in achieving invisibility for electrically large objects.

  15. To calculation of electron-optical characteristics of crossed lenses

    International Nuclear Information System (INIS)

    Afanas'ev, V.P.; Gritsyuk, N.P.; Lachashvili, R.A.; Yavor, S.Ya.

    1979-01-01

    Two approaches are used for theoretical study of crossed lenses (CL), which are formed by plates with slits turned by 90 deg: 1) aberration determination according to axial determination of potential and 2) trajectory analysis of CL. While studying CL of definite configuration it is necessary to take into account aberrations of the highest order. The following conclusions are drawn: the classical method is applied for fast determination of the main characteristics, of CL by means of average power computers (the ''M-220'' or the ''Minsk-32'' computers); the trajectory analysis should be performed by means of power computer (the BESM-6) when it is necessary to obtain more detailed information of the CL, including the trajectory deflection along the system axis, the dimensions of the point source image taking into account the aberrations of the highest order

  16. Spontaneous emission of Alfvénic fluctuations

    Science.gov (United States)

    Yoon, P. H.; López, R. A.; Vafin, S.; Kim, S.; Schlickeiser, R.

    2017-09-01

    Low-frequency fluctuations are pervasively observed in the solar wind. The present paper theoretically calculates the steady state spectra of low-frequency electromagnetic (EM) fluctuations of the Alfvénic type for thermal equilibrium plasma. The analysis is based upon a recently formulated theory of spontaneously emitted EM fluctuations in magnetized thermal plasmas. It is found that the fluctuations in the magnetosonic mode branch is constant, while the kinetic Alfvénic mode spectrum is dependent on a form factor that is a function of perpendicular wave number. Potential applicability of the present work in the wider context of heliospheric research is also discussed.

  17. Effects of barrier fluctuation on the tunneling dynamics in the ...

    Indian Academy of Sciences (India)

    Abstract. We present a numerical investigation of the tunneling dynamics of a particle moving in a bistable potential with fluctuating barrier which is coupled to a non-integrable classical system and study the interplay between classical chaos and barrier fluctuation in the tunneling dynamics. We found that the coupling of the ...

  18. 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',

  19. 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.

  20. 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

  1. 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.

  2. Lenses generated by intermittent currents

    Science.gov (United States)

    Nof, Doron

    1991-03-01

    A nonlinear mechanism for the generation of anticyclonic lens-like eddies from boundary currents is proposed. In contrast to the familiar generation processes that rely on unstable long waves that grow and close upon themselves or vortex shedding due to the geometry of the boundary, the present mechanism is related to intermittency in the current's mass transport. The essence of the new mechanism is that intermittencies in the transport (such as those in the Denmark Strait or the Mediterranean outflow) lead to unbalanced patches of fluid which break up into a discrete sets of eddies that interact with the boundary. The process is highly nonlinear because both the amplitude and the Rossby number are of order unity. It is modeled as follows: we begin with a rectangular box containing the motionless (light) fluid near the boundary. At, say, t = 0, the conceptual box is removed the unbalanced fluid undergoes two main processes. The first involves the establishment of a set of eddies via breakup and geostrophic adjustment, whereas the second is associated with the interaction of the set with the wall. These two processes are examined independently even though in reality the processes are, obviously, taking place at the same time. To examine the first processes we consider the nonlinear collapse of a (light) rectangular box in the open ocean away from the boundary. The breakup processes involves, of course, some sort of instability (because the patch does not remain intact) but this is not necessarily related to the long wave instability that is usually associated with long gravity currents. The general structures of the resulting final chain of eddies can be computed analytically by using the usual connecting principles, the conservation of potential vorticity and mass. It turns out, however, that the number of eddies and their detailed structure cannot be computed unless one invokes an additional constraint. To resolve this closure difficulty, the integrated angular

  3. 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

  4. 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...

  5. 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.

  6. 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.

  7. 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

  8. 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

  9. Fluctuations in email size

    Science.gov (United States)

    Matsubara, Yoshitsugu; Musashi, Yasuo

    2017-12-01

    The purpose of this study is to explain fluctuations in email size. We have previously investigated the long-term correlations between email send requests and data flow in the system log of the primary staff email server at a university campus, finding that email size frequency follows a power-law distribution with two inflection points, and that the power-law property weakens the correlation of the data flow. However, the mechanism underlying this fluctuation is not completely understood. We collected new log data from both staff and students over six academic years and analyzed the frequency distribution thereof, focusing on the type of content contained in the emails. Furthermore, we obtained permission to collect "Content-Type" log data from the email headers. We therefore collected the staff log data from May 1, 2015 to July 31, 2015, creating two subdistributions. In this paper, we propose a model to explain these subdistributions, which follow log-normal-like distributions. In the log-normal-like model, email senders -consciously or unconsciously- regulate the size of new email sentences according to a normal distribution. The fitting of the model is acceptable for these subdistributions, and the model demonstrates power-law properties for large email sizes. An analysis of the length of new email sentences would be required for further discussion of our model; however, to protect user privacy at the participating organization, we left this analysis for future work. This study provides new knowledge on the properties of email sizes, and our model is expected to contribute to the decision on whether to establish upper size limits in the design of email services.

  10. 3C 220.3: A radio galaxy lensing a submillimeter galaxy

    International Nuclear Information System (INIS)

    Haas, Martin; Westhues, Christian; Chini, Rolf; Leipski, Christian; Klaas, Ulrich; Meisenheimer, Klaus; Barthel, Peter; Koopmans, Léon V. E.; Wilkes, Belinda J.; Bussmann, R. Shane; Willner, S. P.; Ashby, Matthew L. N.; Kuraszkiewicz, Joanna; Vegetti, Simona; Clements, David L.; Fassnacht, Christopher D.; Horesh, Assaf; Lagattuta, David J.; Stern, Daniel; Wylezalek, Dominika

    2014-01-01

    Herschel Space Observatory photometry and extensive multiwavelength follow-up have revealed that the powerful radio galaxy (PRG) 3C 220.3 at z = 0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z = 2.221. At an observed wavelength of 1 mm, the SMG is lensed into three distinct images. In the observed near infrared, these images are connected by an arc of ∼1''.8 radius forming an Einstein half-ring centered near the radio galaxy. In visible light, only the arc is apparent. 3C 220.3 is the only known instance of strong galaxy-scale lensing by a PRG not located in a galaxy cluster and therefore it offers the potential to probe the dark matter content of the radio galaxy host. Lens modeling rejects a single lens, but two lenses centered on the radio galaxy host A and a companion B, separated by 1''.5, provide a fit consistent with all data and reveal faint candidates for the predicted fourth and fifth images. The model does not require an extended common dark matter halo, consistent with the absence of extended bright X-ray emission on our Chandra image. The projected dark matter fractions within the Einstein radii of A (1''.02) and B (0''.61) are about 0.4 ± 0.3 and 0.55 ± 0.3. The mass to i-band light ratios of A and B, M/L i ∼8±4 M ⊙ L ⊙ −1 , appear comparable to those of radio-quiet lensing galaxies at the same redshift in the CfA-Arizona Space Telescope LEns Survey, Lenses Structure and Dynamics, and Strong Lenses in the Legacy Survey samples. The lensed SMG is extremely bright with observed f(250 μm) = 440 mJy owing to a magnification factor μ ∼ 10. The SMG spectrum shows luminous, narrow C IV λ1549 Å emission, revealing that the SMG houses a hidden quasar in addition to a violent starburst. Multicolor image reconstruction of the SMG indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive of cones through which UV light escapes a dust

  11. 3C 220.3: A radio galaxy lensing a submillimeter galaxy

    Energy Technology Data Exchange (ETDEWEB)

    Haas, Martin; Westhues, Christian; Chini, Rolf [Astronomisches Institut, Ruhr Universität, Bochum (Germany); Leipski, Christian; Klaas, Ulrich; Meisenheimer, Klaus [Max-Planck-Institut für Astronomie, Heidelberg (Germany); Barthel, Peter; Koopmans, Léon V. E. [Kapteyn Astronomical Institute, University of Groningen (Netherlands); Wilkes, Belinda J.; Bussmann, R. Shane; Willner, S. P.; Ashby, Matthew L. N.; Kuraszkiewicz, Joanna [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Vegetti, Simona [Max-Planck-Institut für Astrophysik, Garching (Germany); Clements, David L. [Imperial College, London (United Kingdom); Fassnacht, Christopher D. [University of California, Davis, CA (United States); Horesh, Assaf [Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA (United States); Lagattuta, David J. [Centre for Astrophysics and Supercomputing, Swinburne University of Technology, Hawthorn (Australia); Stern, Daniel; Wylezalek, Dominika, E-mail: haas@astro.rub.de [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States)

    2014-07-20

    Herschel Space Observatory photometry and extensive multiwavelength follow-up have revealed that the powerful radio galaxy (PRG) 3C 220.3 at z = 0.685 acts as a gravitational lens for a background submillimeter galaxy (SMG) at z = 2.221. At an observed wavelength of 1 mm, the SMG is lensed into three distinct images. In the observed near infrared, these images are connected by an arc of ∼1''.8 radius forming an Einstein half-ring centered near the radio galaxy. In visible light, only the arc is apparent. 3C 220.3 is the only known instance of strong galaxy-scale lensing by a PRG not located in a galaxy cluster and therefore it offers the potential to probe the dark matter content of the radio galaxy host. Lens modeling rejects a single lens, but two lenses centered on the radio galaxy host A and a companion B, separated by 1''.5, provide a fit consistent with all data and reveal faint candidates for the predicted fourth and fifth images. The model does not require an extended common dark matter halo, consistent with the absence of extended bright X-ray emission on our Chandra image. The projected dark matter fractions within the Einstein radii of A (1''.02) and B (0''.61) are about 0.4 ± 0.3 and 0.55 ± 0.3. The mass to i-band light ratios of A and B, M/L{sub i}∼8±4 M{sub ⊙} L{sub ⊙}{sup −1}, appear comparable to those of radio-quiet lensing galaxies at the same redshift in the CfA-Arizona Space Telescope LEns Survey, Lenses Structure and Dynamics, and Strong Lenses in the Legacy Survey samples. The lensed SMG is extremely bright with observed f(250 μm) = 440 mJy owing to a magnification factor μ ∼ 10. The SMG spectrum shows luminous, narrow C IV λ1549 Å emission, revealing that the SMG houses a hidden quasar in addition to a violent starburst. Multicolor image reconstruction of the SMG indicates a bipolar morphology of the emitted ultraviolet (UV) light suggestive of cones through which UV light escapes a

  12. 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.

  13. Gravitational corrections to light propagation in a perturbed FLRW-universe and corresponding weak lensing spectra

    Science.gov (United States)

    Cuesta-Lazaro, Carolina; Quera-Bofarull, Arnau; Reischke, Robert; Schäfer, Björn Malte

    2018-03-01

    When the gravitational lensing of the large-scale structure is calculated from a cosmological model a few assumptions enter: (i) one assumes that the photons follow unperturbed background geodesics, which is usually referred to as the Born-approximation, (ii) the lenses move slowly, (iii) the source-redshift distribution is evaluated relative to the background quantities and (iv) the lensing effect is linear in the gravitational potential. Even though these approximations are small individually they could sum up, especially since they include local effects such as the Sachs-Wolfe and peculiar motion, but also non-local ones like the Born-approximation and the integrated Sachs-Wolfe effect. In this work we will address all points mentioned and perturbatively calculate the effect on a tomographic cosmic shear power spectrum of each effect individually as well as all cross-correlations. Our findings show that each effect is at least 4 to 5 orders of magnitude below the leading order lensing signal. Finally we sum up all effects to estimate the overall impact on parameter estimation by a future cosmological weak lensing survey such as Euclid in a wCDM cosmology with parametrisation Ωm, σ8, ns, h, w0 and wa, using 5 tomographic bins. We consistently find a parameter bias of 10-5, which is therefore completely negligible for all practical purposes, confirming that other effects such as intrinsic alignments, magnification bias and uncertainties in the redshift distribution will be the dominant systematic source in future surveys.

  14. Big Bang or vacuum fluctuation

    International Nuclear Information System (INIS)

    Zel'dovich, Ya.B.

    1980-01-01

    Some general properties of vacuum fluctuations in quantum field theory are described. The connection between the ''energy dominance'' of the energy density of vacuum fluctuations in curved space-time and the presence of singularity is discussed. It is pointed out that a de-Sitter space-time (with the energy density of the vacuum fluctuations in the Einstein equations) that matches the expanding Friedman solution may describe the history of the Universe before the Big Bang. (P.L.)

  15. 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.

  16. 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

  17. 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

  18. 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

  19. 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...

  20. 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.

  1. 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

  2. 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.

  3. 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.

  4. 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.

  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. 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.

  7. 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

  8. 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.

  9. UV solid state laser ablation of intraocular lenses

    Science.gov (United States)

    Apostolopoulos, A.; Lagiou, D. P.; Evangelatos, Ch.; Spyratou, E.; Bacharis, C.; Makropoulou, M.; Serafetinides, A. A.

    2013-06-01

    Commercially available intraocular lenses (IOLs) are manufactured from silicone and acrylic, both rigid (e.g. PMMA) and foldable (hydrophobic or hydrophilic acrylic biomaterials), behaving different mechanical and optical properties. Recently, the use of apodizing technology to design new diffractive-refractive multifocals improved the refractive outcome of these intraocular lenses, providing good distant and near vision. There is also a major ongoing effort to refine laser refractive surgery to correct other defects besides conventional refractive errors. Using phakic IOLs to treat high myopia potentially provides better predictability and optical quality than corneal-based refractive surgery. The aim of this work was to investigate the effect of laser ablation on IOL surface shaping, by drilling circular arrays of holes, with a homemade motorized rotation stage, and scattered holes on the polymer surface. In material science, the most popular lasers used for polymer machining are the UV lasers, and, therefore, we tried in this work the 3rd and the 5th harmonic of a Q-switched Nd:YAG laser (λ=355 nm and λ=213 nm respectively). The morphology of the ablated IOL surface was examined with a scanning electron microscope (SEM, Fei - Innova Nanoscope) at various laser parameters. Quantitative measurements were performed with a contact profilometer (Dektak-150), in which a mechanical stylus scanned across the surface of gold-coated IOLs (after SEM imaging) to measure variations in surface height and, finally, the ablation rates were also mathematically simulated for depicting the possible laser ablation mechanism(s). The experimental results and the theoretical modelling of UV laser interaction with polymeric IOLs are discussed in relation with the physical (optical, mechanical and thermal) properties of the material, in addition to laser radiation parameters (laser energy fluence, number of pulses). The qualitative aspects of laser ablation at λ=213 nm reveal a

  10. 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.

  11. Fluctuations of pT from initial size fluctuations

    International Nuclear Information System (INIS)

    Chojnacki, M.; Broniowski, W.; Obara, L.

    2010-01-01

    We investigate the initial transverse size of the source, which comes directly from the Glauber treatment of the earliest stage of relativistic heavy-ion collisions. After the hydrodynamic evolution stage the fluctuations in the transverse velocity flow at the hadronic freeze-out are transformed into the even-by-event fluctuations of the average transverse momentum. The Glauber phase is simulated by GLISSANDO and followed by a realistic hydrodynamic evolution stage. The statistical hadronization is performed by the THERMINATOR. We describe the pT fluctuations at RHIC, in particular the magnitude of the effect, its centrality dependence, and the weak dependence on the incident energy. The results show that the observed event-by-event p T fluctuations are mainly caused by the initial source size fluctuations. (author)

  12. [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.

  13. Fabrication of miniature elastomer lenses with programmable liquid mold for smartphone microscopy: curing polydimethylsiloxane with in situ curvature control

    Science.gov (United States)

    Karunakaran, Bhuvaneshwari; Tharion, Joseph; Dhawangale, Arvind Ramrao; Paul, Debjani; Mukherji, Soumyo

    2018-02-01

    Miniature lenses can transform commercial imaging systems, e.g., smartphones and webcams, into powerful, low-cost, handheld microscopes. To date, the reproducible fabrication of polymer lenses is still a challenge as they require controlled dispensing of viscous liquid. This paper reports a reproducible lens fabrication technique using liquid mold with programmable curvature and off-the-shelf materials. The lens curvature is controlled during fabrication by tuning the curvature of an interface of two immiscible liquids [polydimethylsiloxane (PDMS) and glycerol]. The curvature control is implemented using a visual feedback system, which includes a software-based guiding system to produce lenses of desired curvature. The technique allows PDMS lens fabrication of a wide range of sizes and focal lengths, within 20 min. The fabrication of two lens diameters: 1 and 5 mm with focal lengths ranging between 1.2 and 11 mm are demonstrated. The lens surface and bulk quality check performed using X-ray microtomography and atomic force microscopy reveal that the lenses are suitable for optical imaging. Furthermore, a smartphone microscope with ˜1.4-μm resolution is developed using a self-assembly of a single high power fabricated lens and microaperture. The lenses have various potential applications, e.g., optofluidics, diagnostics, forensics, and surveillance.

  14. Biomolecules: Fluctuations and relaxations

    Science.gov (United States)

    Parak, F.; Ostermann, A.; Gassmann, A.; Scherk, C.; Chong, S.-H.; Kidera, A.; Go, N.

    1999-10-01

    The normal-mode refinement of X-ray crystallographic data opened a new possibility to analyze the mean-square displacements in a protein molecule. A comparison of the X-ray structure of myoglobin at several temperatures with Mössbauer data is performed. In the low-temperature regime below 180 K the iron mean-square displacements obtained by Mössbauer spectroscopy are in good agreement with a normal-mode analysis. The X-ray mean-square displacements at the position of the iron, after the motion originated from the external degrees of freedom are subtracted, have practically the same temperature dependence as those from Mössbauer spectroscopy. The difference between the X-ray mean-square displacements and those predicted by normal-mode analysis measures the distribution of molecules into conformational substates. Above 180 K the Mössbauer effect indicates fluctuations between conformational substates. The relaxation from a Fe(III) conformation to a Fe(II) conformation is shown for superoxide dismutase of Propionibacterium shermanii.

  15. 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.

  16. 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.

  17. 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...

  18. Nonequilibrium fluctuations in a resistor.

    Science.gov (United States)

    Garnier, N; Ciliberto, S

    2005-06-01

    In small systems where relevant energies are comparable to thermal agitation, fluctuations are of the order of average values. In systems in thermodynamical equilibrium, the variance of these fluctuations can be related to the dissipation constant in the system, exploiting the fluctuation-dissipation theorem. In nonequilibrium steady systems, fluctuations theorems (FT) additionally describe symmetry properties of the probability density functions (PDFs) of the fluctuations of injected and dissipated energies. We experimentally probe a model system: an electrical dipole driven out of equilibrium by a small constant current I, and show that FT are experimentally accessible and valid. Furthermore, we stress that FT can be used to measure the dissipated power P = R I2 in the system by just studying the PDFs' symmetries.

  19. Suppressing Quantum Fluctuations in Classicalization

    CERN Document Server

    Vikman, Alexander

    2013-01-01

    We study vacuum quantum fluctuations of simple Nambu-Goldstone bosons - derivatively coupled single scalar-field theories possessing shift-symmetry in field space. We argue that quantum fluctuations of the interacting field can be drastically suppressed with respect to the free-field case. Moreover, the power-spectrum of these fluctuations can soften to become red for sufficiently small scales. In quasiclassical approximation, we demonstrate that this suppression can only occur for those theories that admit such classical static backgrounds around which small perturbations propagate faster than light. Thus a quasiclassical softening of quantum fluctuations is only possible for theories which classicalize instead of having a usual Lorentz invariant and local Wilsonian UV- completion. We illustrate our analysis by estimating the quantum fluctuations for the DBI-like theories.

  20. Gravitons and light cone fluctuations

    International Nuclear Information System (INIS)

    Ford, L.H.

    1995-01-01

    Gravitons in a squeezed vacuum state, the natural result of quantum creation in the early Universe or by black holes, will introduce metric fluctuations. These metric fluctuations will introduce fluctuations of the light cone. It is shown that when the various two-point functions of a quantized field are averaged over the metric fluctuations, the light cone singularity disappears for distinct points. The metric-averaged functions remain singular in the limit of coincident points. The metric-averaged retarded Green's function for a massless field becomes a Gaussian which is nonzero both inside and outside of the classical light cone. This implies some photons propagate faster than the classical light speed, whereas others propagate slower. The possible effects of metric fluctuations upon one-loop quantum processes are discussed and illustrated by the calculation of the one-loop electron self-energy

  1. 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.

  2. CLASH: Extending galaxy strong lensing to small physical scales with distant sources highly magnified by galaxy cluster members

    International Nuclear Information System (INIS)

    Grillo, C.; Christensen, L.; Gobat, R.; Presotto, V.; Balestra, I.; Nonino, M.; Biviano, A.; Mercurio, A.; Rosati, P.; Vanzella, E.; Graves, G.; Lemze, D.; Ford, H.; Bartelmann, M.; Benitez, N.; Bouwens, R.; Bradley, L.; Coe, D.; Broadhurst, T.; Donahue, M.

    2014-01-01

    We present a complex strong lensing system in which a double source is imaged five times by two early-type galaxies. We take advantage in this target of the extraordinary multi-band photometric data set obtained as part of the Cluster Lensing And Supernova survey with Hubble (CLASH) program, complemented by the spectroscopic measurements of the VLT/VIMOS and FORS2 follow-up campaign. We use a photometric redshift value of 3.7 for the source and confirm spectroscopically the membership of the two lenses to the galaxy cluster MACS J1206.2–0847 at redshift 0.44. We exploit the excellent angular resolution of the HST/ACS images to model the two lenses in terms of singular isothermal sphere profiles and derive robust effective velocity dispersion values of 97 ± 3 and 240 ± 6 km s –1 . Interestingly, the total mass distribution of the cluster is also well characterized by using only the local information contained in this lensing system, which is located at a projected distance of more than 300 kpc from the cluster luminosity center. According to our best-fitting lensing and composite stellar population models, the source is magnified by a total factor of 50 and has a luminous mass of approximately (1.0 ± 0.5) × 10 9 M ☉ (assuming a Salpeter stellar initial mass function). By combining the total and luminous mass estimates of the two lenses, we measure luminous over total mass fractions projected within the effective radii of 0.51 ± 0.21 and 0.80 ± 0.32. Remarkably, with these lenses we can extend the analysis of the mass properties of lens early-type galaxies by factors that are approximately two and three times smaller than previously done with regard to, respectively, velocity dispersion and luminous mass. The comparison of the total and luminous quantities of our lenses with those of astrophysical objects with different physical scales, like massive early-type galaxies and dwarf spheroidals, reveals the potential of studies of this kind for improving our

  3. Thermal fluctuation problems encountered in LMFRs

    International Nuclear Information System (INIS)

    Gelineau, O.; Sperandio, M.; Martin, P.; Ricard, J.B.; Martin, L.; Bougault, A.

    1994-01-01

    One of the most significant problems of LMFBRs deals with thermal fluctuations. The main reason is that LMFBRs operate with sodium coolant at very different temperatures which leads to the existence of several areas of transition between hot and cold sodium. These transitions areas which are the critical points, maybe found in the reactor block as well as in the secondary and auxiliary loops. The characteristics of these thermal fluctuations are not easy to quantify because of their complex (random) behaviour, and often demand the use of thermalhydraulic mock-up tests. A good knowledge of these phenomena is essential because of the potential high level of damage they can induce on structures. Two typical thermal fluctuation problems encountered on operation reactors are described. They were not originally anticipated at the design stage of the former Phenix and the latter Superphenix reactors. Description and the analyses performed to describe the damaging process are explained. A well known thermal fluctuation problem is presented. It is pointed out how the feedback from the damages observed on operating reactors is used to prevent the components from any high cycle fatigue

  4. The use of contact lenses in low vision rehabilitation: optical and therapeutic applications.

    Science.gov (United States)

    Vincent, Stephen J

    2017-09-01

    Ocular pathology that manifests at an early age has the potential to alter the vision-dependent emmetropisation mechanism, which co-ordinates ocular growth throughout childhood. The disruption of this feedback mechanism in children with congenital or early-onset visual impairment often results in the development of significant ametropia, including high levels of spherical refractive error, astigmatism and anisometropia. This review examines the use of contact lenses as a refractive correction, low vision aid and therapeutic intervention in the rehabilitation of patients with bilateral, irreversible visual loss due to congenital ocular disease. The advantages and disadvantages of the use of contact lenses for increased magnification (telescopes and microscopes) or field expansion (reverse telescopes) are discussed, along with the benefits and practical considerations for the correction of pathological high myopia. The historical and present use of therapeutic tinted contact lenses to reduce photosensitivity and nystagmus in achromatopsia, albinism and aniridia are also presented, including clinical considerations for the contact lens practitioner. In addition to the known optical benefits in comparison to spectacles for high levels of ametropia (an improved field of view for myopes and fewer inherent oblique aberrations), contact lenses may be of significant psycho-social benefit for patients with low vision, due to enhanced cosmesis and reduced conspicuity and potential related effects of improved self-esteem and peer acceptance. The contact lens correction of patients with congenital vision impairment can be challenging for both practitioner and patient but should be considered as a potential optical or therapeutic solution in modern low vision rehabilitation. © 2017 Optometry Australia.

  5. Probing the Small-scale Structure in Strongly Lensed Systems via Transdimensional Inference

    Science.gov (United States)

    Daylan, Tansu; Cyr-Racine, Francis-Yan; Diaz Rivero, Ana; Dvorkin, Cora; Finkbeiner, Douglas P.

    2018-02-01

    Strong lensing is a sensitive probe of the small-scale density fluctuations in the Universe. We implement a pipeline to model strongly lensed systems using probabilistic cataloging, which is a transdimensional, hierarchical, and Bayesian framework to sample from a metamodel (union of models with different dimensionality) consistent with observed photon count maps. Probabilistic cataloging allows one to robustly characterize modeling covariances within and across lens models with different numbers of subhalos. Unlike traditional cataloging of subhalos, it does not require model subhalos to improve the goodness of fit above the detection threshold. Instead, it allows the exploitation of all information contained in the photon count maps—for instance, when constraining the subhalo mass function. We further show that, by not including these small subhalos in the lens model, fixed-dimensional inference methods can significantly mismodel the data. Using a simulated Hubble Space Telescope data set, we show that the subhalo mass function can be probed even when many subhalos in the sample catalogs are individually below the detection threshold and would be absent in a traditional catalog. The implemented software, Probabilistic Cataloger (PCAT) is made publicly available at https://github.com/tdaylan/pcat.

  6. A COSMIC MICROWAVE BACKGROUND LENSING MASS MAP AND ITS CORRELATION WITH THE COSMIC INFRARED BACKGROUND

    Energy Technology Data Exchange (ETDEWEB)

    Holder, G. P.; De Haan, T.; Dobbs, M. A.; Dudley, J. [Department of Physics, McGill University, Montreal, Quebec H3A 2T8 (Canada); Viero, M. P.; Bock, J. [California Institute of Technology, Pasadena, CA 91125 (United States); Zahn, O. [Berkeley Center for Cosmological Physics, Department of Physics, University of California, and Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Aird, K. A. [University of Chicago, Chicago, IL 60637 (United States); Benson, B. A.; Bhattacharya, S.; Bleem, L. E.; Carlstrom, J. E.; Chang, C. L.; Crawford, T. M.; Crites, A. T. [Kavli Institute for Cosmological Physics, University of Chicago, Chicago, IL 60637 (United States); Brodwin, M. [Department of Physics and Astronomy, University of Missouri, Kansas City, MO 64110 (United States); Cho, H-M. [NIST Quantum Devices Group, Boulder, CO 80305 (United States); Conley, A. [Center for Astrophysics and Space Astronomy, University of Colorado, Boulder, CO 80309 (United States); George, E. M. [Department of Physics, University of California, Berkeley, CA 94720 (United States); Halverson, N. W. [Department of Astrophysical and Planetary Sciences and Department of Physics, University of Colorado, Boulder, CO 80309 (United States); and others

    2013-07-01

    We use a temperature map of the cosmic microwave background (CMB) obtained using the South Pole Telescope at 150 GHz to construct a map of the gravitational convergence to z {approx} 1100, revealing the fluctuations in the projected mass density. This map shows individual features that are significant at the {approx}4{sigma} level, providing the first image of CMB lensing convergence. We cross-correlate this map with Herschel/SPIRE maps covering 90 deg{sup 2} at wavelengths of 500, 350, and 250 {mu}m. We show that these submillimeter (submm) wavelength maps are strongly correlated with the lensing convergence map, with detection significances in each of the three submm bands ranging from 6.7{sigma} to 8.8{sigma}. We fit the measurement of the cross power spectrum assuming a simple constant bias model and infer bias factors of b = 1.3-1.8, with a statistical uncertainty of 15%, depending on the assumed model for the redshift distribution of the dusty galaxies that are contributing to the Herschel/SPIRE maps.

  7. Quantum fluctuations from thermal fluctuations in Jacobson formalism

    Energy Technology Data Exchange (ETDEWEB)

    Faizal, Mir [University of British Columbia-Okanagan, Irving K. Barber School of Arts and Sciences, Kelowna, BC (Canada); University of Lethbridge, Department of Physics and Astronomy, Lethbridge, AB (Canada); Ashour, Amani; Alcheikh, Mohammad [Damascus University, Mathematics Department, Faculty of Science, Damascus (Syrian Arab Republic); Alasfar, Lina [Universite Clermont Auvergne, Laboratoire de Physique Corpusculaire de Clermont-Ferrand, Aubiere (France); Alsaleh, Salwa; Mahroussah, Ahmed [King Saud University, Department of Physics and Astronomy, Riyadh (Saudi Arabia)

    2017-09-15

    In the Jacobson formalism general relativity is obtained from thermodynamics. This is done by using the Bekenstein-Hawking entropy-area relation. However, as a black hole gets smaller, its temperature will increase. This will cause the thermal fluctuations to also increase, and these will in turn correct the Bekenstein-Hawking entropy-area relation. Furthermore, with the reduction in the size of the black hole, quantum effects will also start to dominate. Just as the general relativity can be obtained from thermodynamics in the Jacobson formalism, we propose that the quantum fluctuations to the geometry can be obtained from thermal fluctuations. (orig.)

  8. 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.

  9. 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.

  10. Effects of thermal fluctuations on thermal inflation

    OpenAIRE

    Hiramatsu, Takashi; Miyamoto, Yuhei; Yokoyama, Jun'ichi

    2014-01-01

    The mechanism of thermal inflation, a relatively short period of accelerated expansion after primordial inflation, is a desirable ingredient for a certain class of particle physics models if they are not to be in contention with the cosmology of the early Universe. Though thermal inflation is most simply described in terms of a thermal effective potential, a thermal environment also gives rise to thermal fluctuations that must be taken into account. We numerically study the effects of these ...

  11. 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.

  12. 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.

  13. 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.

  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. Spectral fluctuations and zeta functions

    International Nuclear Information System (INIS)

    Balazs, N.L.; Schmit, C.; Voros, A.

    1987-01-01

    The study theoretically and numerically the role of the fluctuations of eigenvalue spectra {μ/sub n} in a particular analytical continuation process applied to the (generalized) zeta function Z(s) = Σ/sub n/μ/sub n//sup -s/ for s large and positive. A particularly interesting example is the spectrum of the Laplacian on a triangular domain which tessellates a compact surface of constant negative curvature (of genus two). The authors indeed find that the fluctuations restrict the abscissa of convergence, and also affect the rate of convergence. This then initiates a new approach to the exploration of spectral fluctuations through the convergence of analytical continuation processes

  16. Fluctuation theorem: A critical review

    Science.gov (United States)

    Malek Mansour, M.; Baras, F.

    2017-10-01

    Fluctuation theorem for entropy production is revisited in the framework of stochastic processes. The applicability of the fluctuation theorem to physico-chemical systems and the resulting stochastic thermodynamics were analyzed. Some unexpected limitations are highlighted in the context of jump Markov processes. We have shown that these limitations handicap the ability of the resulting stochastic thermodynamics to correctly describe the state of non-equilibrium systems in terms of the thermodynamic properties of individual processes therein. Finally, we considered the case of diffusion processes and proved that the fluctuation theorem for entropy production becomes irrelevant at the stationary state in the case of one variable systems.

  17. 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.

  18. Edge transport and fluctuation induced turbulence characteristics in early SST-1 plasma

    Energy Technology Data Exchange (ETDEWEB)

    Kakati, B., E-mail: bharat.kakati@ipr.res.in; Pradhan, S., E-mail: pradhan@ipr.res.in; Dhongde, J.; Semwal, P.; Yohan, K.; Banaudha, M.

    2017-02-15

    Highlights: • Anomalous particle transport during the high MHD activity at SST-1. • Electrostatic turbulence is modulated by MHD activity at SST-1 tokamak. • Edge floating potential fluctuations shows poloidal long-range cross correlation. - Abstract: Plasma edge transport characteristics are known to be heavily influenced by the edge fluctuation induced turbulences. These characteristics play a critical role towards the confinement of plasma column in a Tokamak. The edge magnetic fluctuations and its subsequent effect on electrostatic fluctuations have been experimentally investigated for the first time at the edge of the SST-1 plasma column. This paper reports the correlations that exist and is experimentally been observed between the edge densities and floating potential fluctuations with the magnetic fluctuations. The edge density and floating potential fluctuations have been measured with the help of poloidally separated Langmuir probes, whereas the magnetic fluctuations have been measured with poloidally spaced Mirnov coils. Increase in magnetic fluctuations associated with enhanced MHD activities has been found to increase the floating potential and ion saturation current. These observations indicate electrostatic turbulence getting influenced with the MHD activities and reveal the edge anomalous particle transport during SST-1 tokamak discharge. Large-scale coherent structures have been observed in the floating potential fluctuations, indicating long-distance cross correlation in the poloidal directions. From bispectral analysis, a strong nonlinear coupling among the floating potential fluctuations is observed in the low-frequency range about 0–15 kHz.

  19. Precision cosmology with time delay lenses: high resolution imaging requirements

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Xiao-Lei; Liao, Kai [Department of Astronomy, Beijing Normal University, 19 Xinjiekouwai Street, Beijing, 100875 (China); Treu, Tommaso; Agnello, Adriano [Department of Physics, University of California, Broida Hall, Santa Barbara, CA 93106 (United States); Auger, Matthew W. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); Marshall, Philip J., E-mail: xlmeng919@gmail.com, E-mail: tt@astro.ucla.edu, E-mail: aagnello@physics.ucsb.edu, E-mail: mauger@ast.cam.ac.uk, E-mail: liaokai@mail.bnu.edu.cn, E-mail: dr.phil.marshall@gmail.com [Kavli Institute for Particle Astrophysics and Cosmology, Stanford University, 452 Lomita Mall, Stanford, CA 94305 (United States)

    2015-09-01

    Lens time delays are a powerful probe of cosmology, provided that the gravitational potential of the main deflector can be modeled with sufficient precision. Recent work has shown that this can be achieved by detailed modeling of the host galaxies of lensed quasars, which appear as ''Einstein Rings'' in high resolution images. The distortion of these arcs and counter-arcs, as measured over a large number of pixels, provides tight constraints on the difference between the gravitational potential between the quasar image positions, and thus on cosmology in combination with the measured time delay. We carry out a systematic exploration of the high resolution imaging required to exploit the thousands of lensed quasars that will be discovered by current and upcoming surveys with the next decade. Specifically, we simulate realistic lens systems as imaged by the Hubble Space Telescope (HST), James Webb Space Telescope (JWST), and ground based adaptive optics images taken with Keck or the Thirty Meter Telescope (TMT). We compare the performance of these pointed observations with that of images taken by the Euclid (VIS), Wide-Field Infrared Survey Telescope (WFIRST) and Large Synoptic Survey Telescope (LSST) surveys. We use as our metric the precision with which the slope γ' of the total mass density profile ρ{sub tot}∝ r{sup −γ'} for the main deflector can be measured. Ideally, we require that the statistical error on γ' be less than 0.02, such that it is subdominant to other sources of random and systematic uncertainties. We find that survey data will likely have sufficient depth and resolution to meet the target only for the brighter gravitational lens systems, comparable to those discovered by the SDSS survey. For fainter systems, that will be discovered by current and future surveys, targeted follow-up will be required. However, the exposure time required with upcoming facilitites such as JWST, the Keck Next Generation

  20. Precision cosmology with time delay lenses: High resolution imaging requirements

    Energy Technology Data Exchange (ETDEWEB)

    Meng, Xiao -Lei [Beijing Normal Univ., Beijing (China); Univ. of California, Santa Barbara, CA (United States); Treu, Tommaso [Univ. of California, Santa Barbara, CA (United States); Univ. of California, Los Angeles, CA (United States); Agnello, Adriano [Univ. of California, Santa Barbara, CA (United States); Univ. of California, Los Angeles, CA (United States); Auger, Matthew W. [Univ. of Cambridge, Cambridge (United Kingdom); Liao, Kai [Beijing Normal Univ., Beijing (China); Univ. of California, Santa Barbara, CA (United States); Univ. of California, Los Angeles, CA (United States); Marshall, Philip J. [Stanford Univ., Stanford, CA (United States)

    2015-09-28

    Lens time delays are a powerful probe of cosmology, provided that the gravitational potential of the main deflector can be modeled with sufficient precision. Recent work has shown that this can be achieved by detailed modeling of the host galaxies of lensed quasars, which appear as ``Einstein Rings'' in high resolution images. The distortion of these arcs and counter-arcs, as measured over a large number of pixels, provides tight constraints on the difference between the gravitational potential between the quasar image positions, and thus on cosmology in combination with the measured time delay. We carry out a systematic exploration of the high resolution imaging required to exploit the thousands of lensed quasars that will be discovered by current and upcoming surveys with the next decade. Specifically, we simulate realistic lens systems as imaged by the Hubble Space Telescope (HST), James Webb Space Telescope (JWST), and ground based adaptive optics images taken with Keck or the Thirty Meter Telescope (TMT). We compare the performance of these pointed observations with that of images taken by the Euclid (VIS), Wide-Field Infrared Survey Telescope (WFIRST) and Large Synoptic Survey Telescope (LSST) surveys. We use as our metric the precision with which the slope γ' of the total mass density profile ρtot∝ r–γ' for the main deflector can be measured. Ideally, we require that the statistical error on γ' be less than 0.02, such that it is subdominant to other sources of random and systematic uncertainties. We find that survey data will likely have sufficient depth and resolution to meet the target only for the brighter gravitational lens systems, comparable to those discovered by the SDSS survey. For fainter systems, that will be discovered by current and future surveys, targeted follow-up will be required. Furthermore, the exposure time required with upcoming facilitites such as JWST, the Keck Next Generation Adaptive

  1. 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...

  2. The Fluctuation Niche in Plants

    International Nuclear Information System (INIS)

    Terradas, J.; Penuelas, J.; Lloret, F.; Penuelas, J.

    2009-01-01

    Classical approaches to niche in coexisting plants have undervalued temporal fluctuations. We propose that fluctuation niche is an important dimension of the total niche and interacts with habitat and life-history niches to provide a better understanding of the multidimensional niche space where ecological interactions occur. To scale a fluctuation niche, it is necessary to relate environmental constrictions or species performance not only to the absolute values of the usual environmental and eco physiological variables but also to their variances or other measures of variability. We use Mediterranean plant communities as examples, because they present characteristic large seasonal and inter annual fluctuations in water and nutrient availabilities, along an episodic-constant gradient, and because the plant responses include a number of syndromes coupled to this gradient.

  3. The Fluctuation Niche in Plants

    Directory of Open Access Journals (Sweden)

    Jaume Terradas

    2009-01-01

    Full Text Available Classical approaches to niche in coexisting plants have undervalued temporal fluctuations. We propose that fluctuation niche is an important dimension of the total niche and interacts with habitat and life-history niches to provide a better understanding of the multidimensional niche space where ecological interactions occur. To scale a fluctuation niche, it is necessary to relate environmental constrictions or species performance not only to the absolute values of the usual environmental and ecophysiological variables but also to their variances or other measures of variability. We use Mediterranean plant communities as examples, because they present characteristic large seasonal and interannual fluctuations in water and nutrient availabilities, along an episodic-constant gradient, and because the plant responses include a number of syndromes coupled to this gradient.

  4. Molecular evolution under fitness fluctuations.

    Science.gov (United States)

    Mustonen, Ville; Lässig, Michael

    2008-03-14

    Molecular evolution is a stochastic process governed by fitness, mutations, and reproductive fluctuations in a population. Here, we study evolution where fitness itself is stochastic, with random switches in the direction of selection at individual genomic loci. As the correlation time of these fluctuations becomes larger than the diffusion time of mutations within the population, fitness changes from an annealed to a quenched random variable. We show that the rate of evolution has its maximum in the crossover regime, where both time scales are comparable. Adaptive evolution emerges in the quenched fitness regime (evidence for such fitness fluctuations has recently been found in genomic data). The joint statistical theory of reproductive and fitness fluctuations establishes a conceptual connection between evolutionary genetics and statistical physics of disordered systems.

  5. Fluctuating attention in Parkinson's disease

    DEFF Research Database (Denmark)

    Starrfelt, Randi; Aarsland, Dag; Janvin, Carmen

    2001-01-01

    great variability in performance in reactiontime tasks. Aiming to investigate fluctuation of attention in PD, we re- analysed data from a cue-target reactiontime task, specifically searching for differences in variability between patients and controls. The subjects included were a representative group...... a significant difference (pattention might be fluctuating on a moment to moment basis in PD. Some of the PD patients have also been tested with a choice reaction time...... task, shown by Walker et al. (2000) to be sensi- tive to fluctuation of cognition in DLB patients. Preliminary data-analysis indicate that PD patients also show considerable intra-individual variation in performance on this test. These findings suggest that fluctuating attention and cogni- tion...

  6. Fluctuations and Instability in Sedimentation

    KAUST Repository

    Guazzelli, Élisabeth

    2011-01-21

    This review concentrates on the fluctuations of the velocities of sedimenting spheres, and on the structural instability of a suspension of settling fibers. For many years, theoretical estimates and numerical simulations predicted the fluctuations of the velocities of spheres to increase with the size of the container, whereas experiments found no such variation. Two ideas have increased our understanding. First, the correlation length of the velocity fluctuations was found experimentally to be 20 interparticle separations. Second, in dilute suspensions, a vertical variation in the concentration due to the spreading of the front with the clear fluid can inhibit the velocity fluctuations. In a very dilute regime, a homogeneous suspension of fibers suffers a spontaneous instability in which fast descending fiber-rich columns are separated by rising fiber-sparse columns. In a semidilute regime, the settling is hindered, more so than for spheres. © 2011 by Annual Reviews. All rights reserved.

  7. Nonequilibrium quantum fluctuations of work.

    Science.gov (United States)

    Allahverdyan, A E

    2014-09-01

    The concept of work is basic for statistical thermodynamics. To gain a fuller understanding of work and its (quantum) features, it needs to be represented as an average of a fluctuating quantity. Here I focus on the work done between two moments of time for a thermally isolated quantum system driven by a time-dependent Hamiltonian. I formulate two natural conditions needed for the fluctuating work to be physically meaningful for a system that starts its evolution from a nonequilibrium state. The existing definitions do not satisfy these conditions due to issues that are traced back to noncommutativity. I propose a definition of fluctuating work that is free of previous drawbacks and that applies for a wide class of nonequilibrium initial states. It allows the deduction of a generalized work-fluctuation theorem that applies for an arbitrary (out-of-equilibrium) initial state.

  8. 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 ...

  9. 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.

  10. 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.

  11. [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.

  12. 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...

  13. 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 ...

  14. 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.

  15. 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.

  16. 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.

  17. Primordial fluctuations from nonlinear couplings

    International Nuclear Information System (INIS)

    Calzetta, E.A.; Gonorazky, S.

    1997-01-01

    We study the spectrum of primordial fluctuations in theories where the inflaton field is nonlinearly coupled to massless fields and/or to itself. Conformally invariant theories generically predict a scale-invariant spectrum. Scales entering the theory through infrared divergences cause logarithmic corrections to the spectrum, tilting it towards the blue. We discuss in some detail whether these fluctuations are quantum or classical in nature. copyright 1997 The American Physical Society

  18. 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

  19. Memory versus fluctuations in heavy ion fusion

    Science.gov (United States)

    Chushnyakova, M. V.; Gontchar, I. I.

    2013-09-01

    We model collisions of complex nuclei leading to capture using the Langevin equations, with white and colored noises and with instant and retarding friction, respectively. The friction force is supposed to be proportional to the squared derivative of the strong nucleus-nucleus interaction potential (SnnP). The SnnP is calculated within the framework of the double folding model with the density-dependent M3Y NN-forces possessing the finite range exchange term. Comparing results obtained in the presence and in the absence of fluctuations, we found that the fluctuations influence the capture cross sections weakly, typically within 5%. In contradistinction, the influence of the memory effects is found to be about 20%.

  20. 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.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. The reliability and validity of hand-held refractometry water content measures of hydrogel lenses.

    Science.gov (United States)

    Nichols, Jason J; Mitchell, G Lynn; Good, Gregory W

    2003-06-01

    To investigate within- and between-examiner reliability and validity of hand-held refractometry water content measures of hydrogel lenses. Nineteen lenses of various nominal water contents were examined by two examiners on two occasions separated by 1 hour. An Atago N2 hand-held refractometer was used for all water content measures. Lenses were presented in a random order to each examiner by a third party, and examiners were masked to any potential lens identifiers. Intraclass correlation coefficients (ICC), 95% limits of agreement, and Wilcoxon signed rank test were used to characterize the within- and between-examiner reliability and validity of lens water content measures. Within-examiner reliability was excellent (ICC, 0.97; 95% limits of agreement, -3.6% to +5.7%), and the inter-visit mean difference of 1.1 +/- 2.4% was not biased (p = 0.08). Between-examiner reliability was also excellent (ICC, 0.98; 95% limits of agreement, -4.1% to +3.9%). The mean difference between examiners was -0.1 +/- 2.1% (p = 0.83). The mean difference between the nominally reported water content and our water content measures was -2.1 +/- 1.7% (p refractometry and is material dependent. Therefore, investigators may need to account for bias when measuring hydrogel lens water content via hand-held refractometry.

  10. Caustics of 1/r{sup n} binary gravitational lenses: from galactic haloes to exotic matter

    Energy Technology Data Exchange (ETDEWEB)

    Bozza, V.; Melchiorre, C., E-mail: valboz@physics.unisa.it, E-mail: cmelchiorre@unisa.it [Dipartimento di Fisica ' E.R. Caianiello' , Università di Salerno, Via Giovanni Paolo II 132, I-84084 Fisciano (Italy)

    2016-03-01

    We investigate the caustic topologies for binary gravitational lenses made up of two objects whose gravitational potential declines as 1/r{sup n}. With n<1 this corresponds to power-law dust distributions like the singular isothermal sphere. The n>1 regime can be obtained with some violations of the energy conditions, one famous example being the Ellis wormhole. Gravitational lensing provides a natural arena to distinguish and identify such exotic objects in our Universe. We find that there are still three topologies for caustics as in the standard Schwarzschild binary lens, with the main novelty coming from the secondary caustics of the close topology, which become huge at higher n. After drawing caustics by numerical methods, we derive a large amount of analytical formulae in all limits that are useful to provide deeper insight in the mathematics of the problem. Our study is useful to better understand the phenomenology of galaxy lensing in clusters as well as the distinct signatures of exotic matter in complex systems.

  11. Microbial contamination of soft contact lenses & accessories in asymptomatic contact lens users.

    Science.gov (United States)

    Thakur, Deeksha V; Gaikwad, Ujjwala N

    2014-08-01

    With increasing use of soft contact lenses the incidence of contact lens induced infections is also increasing. This study was aimed to assess the knowledge of new and existing contact lens users about the risk of microbial contamination associated with improper use and maintenance of contact lenses, type of microbial flora involved and their potential to cause ophthalmic infections. Four samples each from 50 participants (n=200) were collected from the lenses, lens care solutions, lens care solution bottles and lens cases along with a questionnaire regarding their lens use. The samples were inoculated onto sheep blood agar, Mac Conkey's agar and Sabouraud's dextrose agar. Organisms were identified using standard laboratory protocols. Overall rate of microbial contamination among the total samples was 52 per cent. The most and the least contaminated samples were found to be lens cases (62%) and lens care solution (42%), respectively. The most frequently isolated contaminant was Staphylococcus aureus (21%) followed by Pseudomonas species (19.5%). Majority (64%) of the participants showed medium grade of compliance to lens cleaning practices. Rate of contamination was 100 and 93.75 per cent respectively in those participants who showed low and medium compliance to lens care practices as compared to those who had high level of compliance (43.75%) (PLens care practices amongst the participants were not optimum which resulted into high level contamination. Hence, creating awareness among the users about the lens care practices and regular cleaning and replacements of lens cases are required.

  12. 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.

  13. STRONG GRAVITATIONAL LENSING BY THE SUPER-MASSIVE cD GALAXY IN ABELL 3827

    International Nuclear Information System (INIS)

    Carrasco, E. R.; Gomez, P. L.; Lee, H.; Diaz, R.; Bergmann, M.; Turner, J. E. H.; Miller, B. W.; West, M. J.; Verdugo, T.

    2010-01-01

    We have discovered strong gravitational lensing features in the core of the nearby cluster Abell 3827 by analyzing Gemini South GMOS images. The most prominent strong lensing feature is a highly magnified, ring-shaped configuration of four images around the central cD galaxy. GMOS spectroscopic analysis puts this source at z ∼ 0.2. Located ∼20'' away from the central galaxy is a secondary tangential arc feature which has been identified as a background galaxy with z ∼ 0.4. We have modeled the gravitational potential of the cluster core, taking into account the mass from the cluster, the brightest cluster galaxy (BCG), and other galaxies. We derive a total mass of (2.7 ± 0.4) x 10 13 M sun within 37 h -1 kpc. This mass is an order of magnitude larger than that derived from X-ray observations. The total mass derived from lensing data suggests that the BCG in this cluster is perhaps the most massive galaxy in the nearby universe.

  14. NEARBY PLANETARY SYSTEMS AS LENSES DURING PREDICTED CLOSE PASSAGES TO BACKGROUND STARS

    Energy Technology Data Exchange (ETDEWEB)

    Di Stefano, Rosanne; Matthews, James [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Lepine, Sebastien [Department of Astrophysics, Division of Physical Sciences, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States)

    2013-07-10

    The Einstein rings and proper motions of nearby stars tend to be large. Thus, every year some foreground stars within a few hundred parsecs of Earth induce gravitational lensing events in background stars. In some of these cases, the events may exhibit evidence of planets orbiting the nearby star. In fact, planets can even be discovered during relatively distant passages. Here, we study the lensing signatures associated with planets orbiting nearby high-proper-motion stars. We find the following. (1) Wide-orbit planets can be detected for all distances of closest approach between the foreground and background stars, potentially producing independent events long before and/or after the closest approach. (2) Close-orbit planets can be detected for intermediate distances of closest approach, producing quasiperiodic signatures that may occur days or weeks before and after the stellar-lens event. (3) Planets in the so-called zone for resonant lensing can significantly increase the magnification when the distance of closest approach is small, making the stellar-lens event easier to detect, while simultaneously providing evidence for planets. Because approaches close enough to allow planets to be detected can be predicted, we can plan observing strategies to take advantage of the theoretical framework built in this paper, which describes the sequence of expected effects in terms of a sequence of detection regimes.

  15. Improved release of triamcinolone acetonide from medicated soft contact lenses loaded with drug nanosuspensions.

    Science.gov (United States)

    García-Millán, Eva; Quintáns-Carballo, Mónica; Otero-Espinar, Francisco Javier

    2017-06-15

    Drug nanosuspensions (NSs) show a significant potential to improve loading and release properties of the poorly water soluble drug triamcinolone acetonide (TA) from poly(hydroxyethyl methacrylate) (pHEMA) soft contact lenses. In this work, TA NSs were developed by a controlled precipitation method using a fractional factorial Plackett-Burmann design. Poloxamer 407 (PL) and polyvinyl alcohol (PVA) as stabilizing agents were selected. NSs were characterized in terms of their drug content, particle size and morphology. Results indicate that all studied factors, except homogenization speed and sonication, have significant influence on the drug incorporation yield into NSs. Drug nanoparticles showed an interesting size that may be suitable for their incorporation into topical ocular drug delivery systems, as hydrogels. pHEMA hydrogels and daily-wear Hilafilcon B commercial contact lenses (SCLs) were employed to study TA loading capacity and drug release properties using NSs as loading system. Hydrogels have been synthesised by copolymerization of 2-hydroxyethyl methacrylate (HEMA) with methacrylic acid (MA) in accordance with a previous work (García-Millán et al., 2015). Both synthesised hydrogels and SCLs were characterized in terms of their mechanical and physical properties and TA loading and release properties. Selected TA NS was further characterized by studying its physical-chemical stability during the loading process. Results show that the use of TA NSs as loading medium significantly increases drug loading capacity and release of soft contact lenses in comparison with drug saturated solution. Synthesised pHEMA hydrogels and SCLs lenses have good properties as ophthalmic drug delivery systems, but SCLs load higher quantities of drug and release TA in shorter time periods than synthesised pHEMA hydrogel. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. AUTOMATED DETECTION OF GALAXY-SCALE GRAVITATIONAL LENSES IN HIGH-RESOLUTION IMAGING DATA

    International Nuclear Information System (INIS)

    Marshall, Philip J.; Bradac, Marusa; Hogg, David W.; Moustakas, Leonidas A.; Fassnacht, Christopher D.; Schrabback, Tim; Blandford, Roger D.

    2009-01-01

    We expect direct lens modeling to be the key to successful and meaningful automated strong galaxy-scale gravitational lens detection. We have implemented a lens-modeling 'robot' that treats every bright red galaxy (BRG) in a large imaging survey as a potential gravitational lens system. Having optimized a simple model for 'typical' galaxy-scale gravitational lenses, we generate four assessments of model quality that are then used in an automated classification. The robot infers from these four data the lens classification parameter H that a human would have assigned; the inference is performed using a probability distribution generated from a human-classified training set of candidates, including realistic simulated lenses and known false positives drawn from the Hubble Space Telescope (HST) Extended Groth Strip (EGS) survey. We compute the expected purity, completeness, and rejection rate, and find that these statistics can be optimized for a particular application by changing the prior probability distribution for H; this is equivalent to defining the robot's 'character'. Adopting a realistic prior based on expectations for the abundance of lenses, we find that a lens sample may be generated that is ∼100% pure, but only ∼20% complete. This shortfall is due primarily to the oversimplicity of the model of both the lens light and mass. With a more optimistic robot, ∼90% completeness can be achieved while rejecting ∼90% of the candidate objects. The remaining candidates must be classified by human inspectors. Displaying the images used and produced by the robot on a custom 'one-click' web interface, we are able to inspect and classify lens candidates at a rate of a few seconds per system, suggesting that a future 1000 deg. 2 imaging survey containing 10 7 BRGs, and some 10 4 lenses, could be successfully, and reproducibly, searched in a modest amount of time. We have verified our projected survey statistics, albeit at low significance, using the HST EGS data

  17. 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.

  18. Experimental studies of the transient fluctuation theorem using liquid ...

    Indian Academy of Sciences (India)

    (kχ) of the harmonic potential associated with χ for a given applied voltage can be determined by measuring the thermal fluctuation of χ and by the application of the equipartition theorem kχ = kBT/σ2 χ where σ2 χ is the variance of χ. Equipartition theorem has been used extensively for the study of thermal fluctuations of the.

  19. 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.

  20. 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

  1. Contact lenses as drug controlled release systems: a narrative review

    Directory of Open Access Journals (Sweden)

    Helena Prior Filipe

    2016-06-01

    Full Text Available ABSTRACT Topically applied therapy is the most common way to treat ocular diseases, however given the anatomical and physiological constraints of the eye, frequent dosing is required with possible repercussions in terms of patient compliance. Beyond refractive error correction, contact lenses (CLs have, in the last few decades emerged as a potential ophthalmic drug controlled release system (DCRS. Extensive research is underway to understand how to best modify CLs to increase residence time and bioavailability of drugs within therapeutic levels on the ocular surface.These devices may simultaneously correct ametropia and have a role in managing ophthalmic disorders that can hinder CL wear such as dry eye, glaucoma, ocular allergy and cornea infection and injury. In this narrative review the authors explain how the ocular surface structures determine drug diffusion in the eye and summarize the strategies to enhance drug residence time and bioavailability. They synthesize findings and clinical applications of drug soaked CLs as DCRS combined with delivery diffusion barriers, incorporation of functional monomers, ion related controlled release, molecular imprinting, nanoparticles and layering. The authors draw conclusions about the impact of these novel ophthalmic agents delivery systems in improving drug transport in the target tissue and patient compliance, in reducing systemic absorption and undesired side effects, and discuss future perspectives.

  2. Second-order singular pertubative theory for gravitational lenses

    Science.gov (United States)

    Alard, C.

    2018-03-01

    The extension of the singular perturbative approach to the second order is presented in this paper. The general expansion to the second order is derived. The second-order expansion is considered as a small correction to the first-order expansion. Using this approach, it is demonstrated that in practice the second-order expansion is reducible to a first order expansion via a re-definition of the first-order pertubative fields. Even if in usual applications the second-order correction is small the reducibility of the second-order expansion to the first-order expansion indicates a potential degeneracy issue. In general, this degeneracy is hard to break. A useful and simple second-order approximation is the thin source approximation, which offers a direct estimation of the correction. The practical application of the corrections derived in this paper is illustrated by using an elliptical NFW lens model. The second-order pertubative expansion provides a noticeable improvement, even for the simplest case of thin source approximation. To conclude, it is clear that for accurate modelization of gravitational lenses using the perturbative method the second-order perturbative expansion should be considered. In particular, an evaluation of the degeneracy due to the second-order term should be performed, for which the thin source approximation is particularly useful.

  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. 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

  5. Modeling fluctuations in scattered waves

    CERN Document Server

    Jakeman, E

    2006-01-01

    Fluctuations in scattered waves limit the performance of imaging and remote sensing systems that operate on all wavelengths of the electromagnetic spectrum. To better understand these fluctuations, Modeling Fluctuations in Scattered Waves provides a practical guide to the phenomenology, mathematics, and simulation of non-Gaussian noise models and discusses how they can be used to characterize the statistics of scattered waves.Through their discussion of mathematical models, the authors demonstrate the development of new sensing techniques as well as offer intelligent choices that can be made for system analysis. Using experimental results and numerical simulation, the book illustrates the properties and applications of these models. The first two chapters introduce statistical tools and the properties of Gaussian noise, including results on phase statistics. The following chapters describe Gaussian processes and the random walk model, address multiple scattering effects and propagation through an extended med...

  6. Fluctuations in the multiparticle dynamics

    International Nuclear Information System (INIS)

    Bozek, P.; Ploszajczak, M.

    1993-01-01

    The appearance and properties of intermittent fluctuations in physical systems, in particular the formation of rare structures in transport phenomena are discussed. The distribution of fluctuations approaches a limiting log-normal statistical distribution. The log-normal distribution is introduced as a simple parametrization of the energy fluctuations leading to the subthreshold production of particles in nuclear collisions, and it is shown that it fits all available data both for total π 0 production cross section as well as the π 0 kinetic energy spectra for E/A < 90 MeV. It is suggested that the same universal distribution should also describe the subthreshold production of other hadrons like η and K. (author) 36 refs., 11 figs

  7. Herschel extreme lensing line observations: Dynamics of two strongly lensed star-forming galaxies near redshift z = 2

    International Nuclear Information System (INIS)

    Rhoads, James E.; Malhotra, Sangeeta; Allam, Sahar; Carilli, Chris; Combes, Françoise; Finkelstein, Keely; Finkelstein, Steven; Frye, Brenda; Gerin, Maryvonne; Guillard, Pierre; Nesvadba, Nicole; Rigby, Jane; Spaans, Marco; Strauss, Michael A.

    2014-01-01

    We report on two regularly rotating galaxies at redshift z ≈ 2, using high-resolution spectra of the bright [C II] 158 μm emission line from the HIFI instrument on the Herschel Space Observatory. Both SDSS090122.37+181432.3 ( S 0901 ) and SDSSJ120602.09+514229.5 ( t he Clone ) are strongly lensed and show the double-horned line profile that is typical of rotating gas disks. Using a parametric disk model to fit the emission line profiles, we find that S0901 has a rotation speed of vsin (i) ≈ 120 ± 7 km s –1 and a gas velocity dispersion of σ g < 23 km s –1 (1σ). The best-fitting model for the Clone is a rotationally supported disk having vsin (i) ≈ 79 ± 11 km s –1 and σ g ≲ 4 km s –1 (1σ). However, the Clone is also consistent with a family of dispersion-dominated models having σ g = 92 ± 20 km s –1 . Our results showcase the potential of the [C II] line as a kinematic probe of high-redshift galaxy dynamics: [C II] is bright, accessible to heterodyne receivers with exquisite velocity resolution, and traces dense star-forming interstellar gas. Future [C II] line observations with ALMA would offer the further advantage of spatial resolution, allowing a clearer separation between rotation and velocity dispersion.

  8. Origin of cosmological density fluctuations

    International Nuclear Information System (INIS)

    Carr, B.J.

    1984-11-01

    The density fluctuations required to explain the large-scale cosmological structure may have arisen spontaneously as a result of a phase transition in the early Universe. There are several ways in which such fluctuations may have ben produced, and they could have a variety of spectra, so one should not necessarily expect all features of the large-scale structure to derive from a simple power law spectrum. Some features may even result from astrophysical amplification mechanisms rather than gravitational instability. 128 references

  9. 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...

  10. A measurement of gravitational lensing of the cosmic microwave background by galaxy clusters using data from the south pole telescope

    Energy Technology Data Exchange (ETDEWEB)

    Baxter, E. J.; Keisler, R.; Dodelson, S.; Aird, K. A.; Allen, S. W.; Ashby, M. L. N.; Bautz, M.; Bayliss, M.; Benson, B. A.; Bleem, L. E.; Bocquet, S.; Brodwin, M.; Carlstrom, J. E.; Chang, C. L.; Chiu, I.; Cho, H-M.; Clocchiatti, A.; Crawford, T. M.; Crites, A. T.; Desai, S.; Dietrich, J. P.; de Haan, T.; Dobbs, M. A.; Foley, R. J.; Forman, W. R.; George, E. M.; Gladders, M. D.; Gonzalez, A. H.; Halverson, N. W.; Harrington, N. L.; Hennig, C.; Hoekstra, H.; Holder, G. P.; Holzapfel, W. L.; Hou, Z.; Hrubes, J. D.; Jones, C.; Knox, L.; Lee, A. T.; Leitch, E. M.; Liu, J.; Lueker, M.; Luong-Van, D.; Mantz, A.; Marrone, D. P.; McDonald, M.; McMahon, J. J.; Meyer, S. S.; Millea, M.; Mocanu, L. M.; Murray, S. S.; Padin, S.; Pryke, C.; Reichardt, C. L.; Rest, A.; Ruhl, J. E.; Saliwanchik, B. R.; Saro, A.; Sayre, J. T.; Schaffer, K. K.; Shirokoff, E.; Song, J.; Spieler, H. G.; Stalder, B.; Stanford, S. A.; Staniszewski, Z.; Stark, A. A.; Story, K. T.; van Engelen, A.; Vanderlinde, K.; Vieira, J. D.; Vikhlinin, A.; Williamson, R.; Zahn, O.; Zenteno, A.

    2015-06-20

    Clusters of galaxies are expected to gravitationally lens the cosmic microwave background (CMB) and thereby generate a distinct signal in the CMB on arcminute scales. Measurements of this effect can be used to constrain the masses of galaxy clusters with CMB data alone. Here we present a measurement of lensing of the CMB by galaxy clusters using data from the South Pole Telescope (SPT). We develop a maximum likelihood approach to extract the CMB cluster lensing signal and validate the method on mock data. We quantify the effects on our analysis of several potential sources of systematic error and find that they generally act to reduce the best-fit cluster mass. It is estimated that this bias to lower cluster mass is roughly 0.85σ in units of the statistical error bar, although this estimate should be viewed as an upper limit. We apply our maximum likelihood technique to 513 clusters selected via their Sunyaev–Zeldovich (SZ) signatures in SPT data, and rule out the null hypothesis of no lensing at 3.1σ. The lensing-derived mass estimate for the full cluster sample is consistent with that inferred from the SZ flux: ${M}_{200,\\mathrm{lens}}={0.83}_{-0.37}^{+0.38}\\;{M}_{200,\\mathrm{SZ}}$ (68% C.L., statistical error only).

  11. Scrape-off layer-induced beam density fluctuations and their effect on beam emission spectroscopy

    Science.gov (United States)

    Moulton, D.; Marandet, Y.; Tamain, P.; Dif-Pradalier, G.

    2015-07-01

    A statistical model is presented to calculate the magnitude of beam density fluctuations generated by a turbulent scrape-off layer (SOL). It is shown that the SOL can induce neutral beam density fluctuations of a similar magnitude to the plasma density fluctuations in the core, potentially corrupting beam emission spectroscopy measurements. The degree of corruption is quantified by combining simulations of beam and plasma density fluctuations inside a simulated measurement window. A change in pitch angle from the separatrix to the measurement window is found to reduce the effect of beam fluctuations, whose largest effect is to significantly reduce the measured correlation time.

  12. Accommodating intraocular lenses: a critical review of present and future concepts.

    Science.gov (United States)

    Menapace, R; Findl, O; Kriechbaum, K; Leydolt-Koeppl, Ch

    2007-04-01

    fibrosis by extensive capsule polishing did not enhance the functional performance. Dual optic lenses are under clinical investigation and are reported to provide a significant amount of accommodation. However, possible long-term formation of interlenticular opacifications remains to be excluded. Regarding magnet-driven active-shift lens systems, initial clinical experience has been promising. Prevention of fibrotic capsular contraction is crucial, and it has been effectively counteracted with a special capsular tension ring, or lens fixation technique, together with capsule polishing. Lens refilling has been extensively studied in the laboratory and in primates. Though it offers great potential for fully restoring accommodation, a variety of problems must be solved, such as achieving emmetropia in the relaxed state, adequate response to ciliary muscle contraction, satisfying image quality over the entire range of accommodation and sustained functioning. The key problem, however, is again after-cataract prevention. As opposed to psychophysical evaluation techniques, laser interferometry measures what shift lenses are designed to provide: axial shift on accommodative effort. While under pilocarpine some movement was recorded, no movement at all was found under near-point stimulation with any of the lenses currently marketed. In contrast, magnetic-driven active-shift lens systems carry the potential of sufficiently topping up apparent accommodation to provide for clinically useful accommodation while using conventional lens designs with proven after-cataract performance. Dual optic implants significantly increase the impact of axial optic shift. The main potential problem, however, is delayed formation of interlenticular regenerates. Lens refilling procedures offer the potential of fully restoring accommodation due to the great impact of increase in surface curvature on refractive lens power. However, various problems remain to be solved before clinical use can be envisaged

  13. 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

  14. Fluctuation Solution Theory Properties from Molecular Simulation

    DEFF Research Database (Denmark)

    Abildskov, Jens; Wedberg, R.; O’Connell, John P.

    2013-01-01

    The thermodynamic properties obtained in the Fluctuation Solution Theory are based on spatial integrals of molecular TCFs between component pairs in the mixture. Molecular simulation, via either MD or MC calculations, can yield these correlation functions for model inter- and intramolecular...... potential functions. However, system-size limitations and statistical noise cause uncertainties in the functions at long range, and thus uncertainties or errors in the integrals. A number of methods such as truncation, distance shifting, long-range modeling, transforms, DCF matching, finite-size scaling...

  15. Bi-stability resistant to fluctuations

    Science.gov (United States)

    Caruel, M.; Truskinovsky, L.

    2017-12-01

    We study a simple micro-mechanical device that does not lose its snap-through behavior in an environment dominated by fluctuations. The main idea is to have several degrees of freedom that can cooperatively resist the de-synchronizing effect of random perturbations. As an inspiration we use the power stroke machinery of skeletal muscles, which ensures at sub-micron scales and finite temperatures a swift recovery of an abruptly applied slack. In addition to hypersensitive response at finite temperatures, our prototypical Brownian snap spring also exhibits criticality at special values of parameters which is another potentially interesting property for micro-scale engineering applications.

  16. 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.

  17. 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.

  18. 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

  19. 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.

  20. Universal fluctuations in orbital diamagnetism

    Indian Academy of Sciences (India)

    P S Pal

    2018-01-31

    Jan 31, 2018 ... Indian Academy of Sciences https://doi.org/10.1007/s12043-018-1521-5. Universal fluctuations ... dissertation almost a century ago. They had shown that in the presence of constant magnetic field ..... Ph.D. Thesis (Indian Institute of Science, Bengaluru,. 1982). [7] N Kumar and K Vijay Kumar, Europhys. Lett.

  1. Fluctuating hydrodynamics for ionic liquids

    Energy Technology Data Exchange (ETDEWEB)

    Lazaridis, Konstantinos [Department of Mathematics and Statistics, Washington State University, Pullman, 99163 (United States); Wickham, Logan [Department of Computer Science, Washington State University, Richland, 99354 (United States); Voulgarakis, Nikolaos, E-mail: n.voulgarakis@wsu.edu [Department of Mathematics and Statistics, Washington State University, Pullman, 99163 (United States)

    2017-04-25

    We present a mean-field fluctuating hydrodynamics (FHD) method for studying the structural and transport properties of ionic liquids in bulk and near electrified surfaces. The free energy of the system consists of two competing terms: (1) a Landau–Lifshitz functional that models the spontaneous separation of the ionic groups, and (2) the standard mean-field electrostatic interaction between the ions in the liquid. The numerical approach used to solve the resulting FHD-Poisson equations is very efficient and models thermal fluctuations with remarkable accuracy. Such density fluctuations are sufficiently strong to excite the experimentally observed spontaneous formation of liquid nano-domains. Statistical analysis of our simulations provides quantitative information about the properties of ionic liquids, such as the mixing quality, stability, and the size of the nano-domains. Our model, thus, can be adequately parameterized by directly comparing our prediction with experimental measurements and all-atom simulations. Conclusively, this work can serve as a practical mathematical tool for testing various theories and designing more efficient mixtures of ionic liquids. - Highlights: • A new fluctuating hydrodynamics method for ionic liquids. • Description of ionic liquid morphology in bulk and near electrified surfaces. • Direct comparison with experimental measurements.

  2. Fluctuation relation for heat engines

    International Nuclear Information System (INIS)

    Sinitsyn, N A

    2011-01-01

    We derive the exact equality, referred to as the fluctuation relation for heat engines (FRHE), that relates statistics of heat extracted from one of the two heat baths and the work per one cycle of a heat engine operation. Carnot's inequality of classical thermodynamics follows as a direct consequence of the FRHE. (paper)

  3. Reaction rates when barriers fluctuate

    OpenAIRE

    Reimann, Peter

    1999-01-01

    Reaction rates when barriers fluctuate : a path integral approach / P. Hänggi and P. Reimann. - In: International Conference on Path Integrals from peV to TeV : Proceedings of the ... / eds.: R. Casalbuoni ... - Singapore u.a. : World Scientific, 1999. - S. 407-409

  4. Fluctuation conductivity in cuprate superconductors

    Indian Academy of Sciences (India)

    model to be inadequate to describe the fluctuation conductivity in these materials. The modification ... shown by various models which consider several conducting layers per unit cell, with ei- ther interlayer or ..... Pomer et al [6] have observed a large discrepancy of their data measured at 1 tesla from the prediction of eq. (1).

  5. Kondo effect and mesoscopic fluctuations

    Indian Academy of Sciences (India)

    Slave boson/fermion mean-field approach. A complete solution of this problem would presumably involve developing a Fermi liquid theory 'à la Nozières' [15] taking properly into account the mesoscopic fluctuations. A first step in this direction is to use a mean-field treatment based on the slave boson/fermion technique [1] ...

  6. Fluctuations in Hertz chains at equilibrium.

    Science.gov (United States)

    Przedborski, Michelle; Sen, Surajit; Harroun, Thad A

    2017-03-01

    We examine the long-term behavior of nonintegrable, energy-conserved, one-dimensional systems of macroscopic grains interacting via a contact-only generalized Hertz potential and held between stationary walls. Such systems can be set up to have no phononic background excitation and represent examples of a sonic vacuum. Existing dynamical studies showed the absence of energy equipartitioning in such systems, hence their long-term dynamics was described as quasiequilibrium. Here we show that these systems do in fact reach thermal equilibrium at sufficiently long times, as indicated by the calculated heat capacity. As a by-product, we show how fluctuations of system quantities, and thus the distribution functions, are influenced by the Hertz potential. In particular, the variance of the system's kinetic energy probability density function is reduced by a factor related to the contact potential.

  7. 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.

  8. 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.

  9. 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).

  10. 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.

  11. The detection of the imprint of filaments on cosmic microwave background lensing

    Science.gov (United States)

    He, Siyu; Alam, Shadab; Ferraro, Simone; Chen, Yen-Chi; Ho, Shirley

    2018-04-01

    Galaxy redshift surveys, such as the 2-Degree-Field Survey (2dF)1, Sloan Digital Sky Survey (SDSS)2, 6-Degree-Field Survey (6dF)3, Galaxy And Mass Assembly survey (GAMA)4 and VIMOS Public Extragalactic Redshift Survey (VIPERS)5, have shown that the spatial distribution of matter forms a rich web, known as the cosmic web6. Most galaxy survey analyses measure the amplitude of galaxy clustering as a function of scale, ignoring information beyond a small number of summary statistics. Because the matter density field becomes highly non-Gaussian as structure evolves under gravity, we expect other statistical descriptions of the field to provide us with additional information. One way to study the non-Gaussianity is to study filaments, which evolve non-linearly from the initial density fluctuations produced in the primordial Universe. In our study, we report the detection of lensing of the cosmic microwave background (CMB) by filaments, and we apply a null test to confirm our detection. Furthermore, we propose a phenomenological model to interpret the detected signal, and we measure how filaments trace the matter distribution on large scales through filament bias, which we measure to be around 1.5. Our study provides new scope to understand the environmental dependence of galaxy formation. In the future, the joint analysis of lensing and Sunyaev-Zel'dovich observations might reveal the properties of `missing baryons', the vast majority of the gas that resides in the intergalactic medium, which has so far evaded most observations.

  12. 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

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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

  18. 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]).

  19. 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.

  20. The effect of blue-light blocking spectacle lenses on visual performance, macular health and the sleep-wake cycle: a systematic review of the literature.

    Science.gov (United States)

    Lawrenson, John G; Hull, Christopher C; Downie, Laura E

    2017-11-01

    Blue-blocking (BB) spectacle lenses, which attenuate short-wavelength light, are being marketed to alleviate eyestrain and discomfort when using digital devices, improve sleep quality and potentially confer protection from retinal phototoxicity. The aim of this review was to investigate the relative benefits and potential harms of these lenses. We included randomised controlled trials (RCTs), recruiting adults from the general population, which investigated the effect of BB spectacle lenses on visual performance, symptoms of eyestrain or eye fatigue, changes to macular integrity and subjective sleep quality. We searched MEDLINE, EMBASE, the Cochrane Library and clinical trial registers, until 30 April 2017. Risk of bias was assessed using the Cochrane tool. Three studies (with 136 participants) met our inclusion criteria; these had limitations in study design and/or implementation. One study compared the effect of BB lenses with clear lenses on contrast sensitivity (CS) and colour vision (CV) using a pseudo-RCT crossover design; there was no observed difference between lens types (log CS; Mean Difference (MD) = -0.01 [-0.03, 0.01], CV total error score on 100-hue; MD = 1.30 [-7.84, 10.44]). Another study measured critical fusion frequency (CFF), as a proxy for eye fatigue, on wearers of low and high BB lenses, pre- and post- a two-hour computer task. There was no observed difference between low BB and standard lens groups, but there was a less negative change in CFF between the high and low BB groups (MD = 1.81 [0.57, 3.05]). Both studies compared eyestrain symptoms with Likert scales. There was no evidence of inter-group differences for either low BB (MD = 0.00 [-0.22, 0.22]) or high BB lenses (MD = -0.05 [-0.31, 0.21]), nor evidence of a difference in the proportion of participants showing an improvement in symptoms of eyestrain or eye fatigue. One study reported a small improvement in sleep quality in people with self-reported insomnia after wearing

  1. Radiation Doses in Patient Eye Lenses during Interventional Neuroradiology Procedures.

    Science.gov (United States)

    Sánchez, R M; Vañó, E; Fernández, J M; Rosati, S; López-Ibor, L

    2016-03-01

    Eye lenses are among the most sensitive organs to x-ray radiation and may be considered at risk during neurointerventional radiology procedures. The threshold dose to produce eye lens opacities has been recently reduced to 500 mGy by the International Commission on Radiologic Protection. In this article, the authors investigated the radiation doses delivered to patients' eyes during interventional neuroradiology procedures at a university hospital. Small optically stimulated luminescence dosimeters were located over patients' eyes during 5 diagnostic and 31 therapeutic procedures performed in a biplane x-ray system. Phantom measurements were also made to determine the level of radiation to the eye during imaging runs with conebeam CT. The left eye (located toward the lateral C-arm x-ray source) received a 4.5 times greater dose than the right one. The average dose during embolization in the left eye was 300 mGy, with a maximum of 2000 mGy in a single procedure. The patient who received this maximum eye dose needed 6 embolization procedures to treat his high-volume AVM. If one took into account those 6 embolizations, the eye dose could be 2-fold. Sixteen percent of the embolizations resulted in eye doses of >500 mGy. A relevant fraction of patients received eye doses exceeding the threshold of 500 mGy. A careful optimization of the procedures and follow-up of these patients to evaluate potential lens opacities should be considered. © 2016 by American Journal of Neuroradiology.

  2. 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)

  3. 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…

  4. Fluctuation conductivity in cuprate superconductors

    Indian Academy of Sciences (India)

    Abstract. We have measured the in-plane resistivity of Bi2Sr2CaCu2O8+δ and Tl2Ba2. CaCu2O8+δ single crystals in the temperature range 70–300 K. The thermodynamic fluctuations in the conductivity of both the samples start around ∼ 125 K. We find the Lawrence and Doniach [1] model to be inadequate to describe the ...

  5. Random numbers from vacuum fluctuations

    International Nuclear Information System (INIS)

    Shi, Yicheng; Kurtsiefer, Christian; Chng, Brenda

    2016-01-01

    We implement a quantum random number generator based on a balanced homodyne measurement of vacuum fluctuations of the electromagnetic field. The digitized signal is directly processed with a fast randomness extraction scheme based on a linear feedback shift register. The random bit stream is continuously read in a computer at a rate of about 480 Mbit/s and passes an extended test suite for random numbers.

  6. The Discovery and Properties of a Newly Discovered Compact Lensing Cluster CLIO at z=0.42: A unique JWST target

    Science.gov (United States)

    Conselice, Christopher; Griffiths, Alex; Alpaslan, Mehmet; Frye, Brenda; Zitrin, Adi; Diego, Jose; Yan, Haojing; Ma, Zhiyuan; Barone-Nugent, Robert; Bhatawdekar, Rachana; Driver, Simon; Robotham, Aaron; Windhorst, Rogier; Wyithe, Stuart

    2018-01-01

    We present the results of a new study of a unique compact lensing cluster we name CLIO at redshift z = 0.42, discovered through the GAMA survey using spectroscopic redshifts. Compact and massive clusters such as this are understudied, but provide a unique prospective on dark matter distributions and for finding background lensed high-z galaxies. The CLIO cluster was identied for follow up observations due to its almost unique combination of high mass and dark matter halo concentration, as well as having observed lensing arcs from ground based imaging. Using deep FORS2 and Spitzer imaging in combination with MUSE optical spectroscopy we identify 89 cluster members and background sources out to z = 5.79. We describe the physical state of this cluster, finding a strong correlation between environment and galaxy spectral type. We furthermore measure the total mass of CLIO to be 4$\\times 10^{14}$ solar masses . We build and present an initial strong-lensing model for this cluster, and measure a relatively low intracluster light (ICL) fraction of ~7%. Due to its strong potential for lensing background galaxies and its low ICL, the CLIO cluster will be a target for our 110 hour JWST `Webb Medium-Deep Field' (WMDF) GTO program.

  7. Fluctuating hydrodynamics for ionic liquids

    Science.gov (United States)

    Lazaridis, Konstantinos; Wickham, Logan; Voulgarakis, Nikolaos

    2017-04-01

    We present a mean-field fluctuating hydrodynamics (FHD) method for studying the structural and transport properties of ionic liquids in bulk and near electrified surfaces. The free energy of the system consists of two competing terms: (1) a Landau-Lifshitz functional that models the spontaneous separation of the ionic groups, and (2) the standard mean-field electrostatic interaction between the ions in the liquid. The numerical approach used to solve the resulting FHD-Poisson equations is very efficient and models thermal fluctuations with remarkable accuracy. Such density fluctuations are sufficiently strong to excite the experimentally observed spontaneous formation of liquid nano-domains. Statistical analysis of our simulations provides quantitative information about the properties of ionic liquids, such as the mixing quality, stability, and the size of the nano-domains. Our model, thus, can be adequately parameterized by directly comparing our prediction with experimental measurements and all-atom simulations. Conclusively, this work can serve as a practical mathematical tool for testing various theories and designing more efficient mixtures of ionic liquids.

  8. Primordial fluctuations without scalar fields

    Science.gov (United States)

    Magueijo, João; Noller, Johannes

    2010-02-01

    We revisit the question of whether fluctuations in hydrodynamical, adiabatical matter could explain the observed structures in our Universe. We consider matter with variable equation of state w=p0/ɛ0 and a concomitant (under the adiabatic assumption) density dependent speed of sound, cs. We find a limited range of possibilities for a setup when modes start inside the Hubble radius, then leaving it and freezing out. For expanding universes, power-law w(ɛ0) models are ruled out (except when cs2∝w≪1, requiring post-stretching the seeded fluctuations); but sharper profiles in cs do solve the horizon problem. Among these, a phase transition in cs is notable for leading to scale-invariant fluctuations if the initial conditions are thermal. For contracting universes all power-law w(ɛ0) solve the horizon problem, but only one leads to scale-invariance: w∝ɛ02 and cs∝ɛ0. This model bypasses a number of problems with single scalar field cyclic models (for which w is large but constant).

  9. Graviton fluctuations erase the cosmological constant

    Science.gov (United States)

    Wetterich, C.

    2017-10-01

    Graviton fluctuations induce strong non-perturbative infrared renormalization effects for the cosmological constant. The functional renormalization flow drives a positive cosmological constant towards zero, solving the cosmological constant problem without the need to tune parameters. We propose a simple computation of the graviton contribution to the flow of the effective potential for scalar fields. Within variable gravity, with effective Planck mass proportional to the scalar field, we find that the potential increases asymptotically at most quadratically with the scalar field. The solutions of the derived cosmological equations lead to an asymptotically vanishing cosmological ;constant; in the infinite future, providing for dynamical dark energy in the present cosmological epoch. Beyond a solution of the cosmological constant problem, our simplified computation also entails a sizeable positive graviton-induced anomalous dimension for the quartic Higgs coupling in the ultraviolet regime, substantiating the successful prediction of the Higgs boson mass within the asymptotic safety scenario for quantum gravity.

  10. 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.

  11. 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...

  12. 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

  13. 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.

  14. 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.

  15. 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...

  16. 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.

  17. 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.

  18. 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…

  19. 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:…

  20. 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.

  1. 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.

  2. 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.

  3. 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

  4. 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...

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. Measurement of magnetic fluctuation induced energy transport

    International Nuclear Information System (INIS)

    Fiksel, G.; Prager, S.C.; Shen, W.; Stoneking, M.

    1993-11-01

    The local electron energy flux produced by magnetic fluctuations has been measured directly in the MST reversed field pinch (over the radial range r/a > 0.75). The flux, produced by electrons traveling parallel to a fluctuating magnetic field, is obtained from correlation between the fluctuations in the parallel heat flux and the radial magnetic field. The fluctuation induced flux is large (100 kW/cm 2 ) in the ''core'' (r/a 2 ) in the edge

  13. 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

  14. Wall pressure fluctuations in rod bundles

    International Nuclear Information System (INIS)

    Moeller, S.V.

    1990-01-01

    Microphones and hot wires were applied for the measurement of wall pressure fluctuations and velocity fluctuations in rod bundles with several aspect ratios. By means of auto and cross spectral density functions their interdependence was investigated. Results show that the pressure fluctuations in rod bundles are mainly associated with the phenomenon of quasi-periodic flow pulsations between subchannels. (author)

  15. 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.

  16. Microbial contamination of soft contact lenses & accessories in asymptomatic contact lens users

    Directory of Open Access Journals (Sweden)

    Deeksha V Thakur

    2014-01-01

    Full Text Available Background & objectives: With increasing use of soft contact lenses the incidence of contact lens induced infections is also increasing. This study was aimed to assess the knowledge of new and existing contact lens users about the risk of microbial contamination associated with improper use and maintenance of contact lenses, type of microbial flora involved and their potential to cause ophthalmic infections. Methods: Four samples each from 50 participants (n=200 were collected from the lenses, lens care solutions, lens care solution bottles and lens cases along with a questionnaire regarding their lens use. The samples were inoculated onto sheep blood agar, Mac Conkey′s agar and Sabouraud′s dextrose agar. Organisms were identified using standard laboratory protocols. Results: Overall rate of microbial contamination among the total samples was 52 per cent. The most and the least contaminated samples were found to be lens cases (62% and lens care solution (42%, respectively. The most frequently isolated contaminant was Staphylococcus aureus (21% followed by Pseudomonas species (19.5%. Majority (64% of the participants showed medium grade of compliance to lens cleaning practices. Rate of contamination was 100 and 93.75 per cent respectively in those participants who showed low and medium compliance to lens care practices as compared to those who had high level of compliance (43.75% ( p0 <0.05. Interpretation & conclusions: Lens care practices amongst the participants were not optimum which resulted into high level contamination. Hence, creating awareness among the users about the lens care practices and regular cleaning and replacements of lens cases are required.

  17. 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.

  18. 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.

  19. 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

  20. 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.

  1. 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.

  2. Distinguishing f(R) theories from general relativity by gravitational lensing effect

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Hongguang [Beijing Normal University, Department of Physics, Beijing (China); Aix Marseille Universite et Universite de Toulon, Centre de Physique Theorique (UMR 7332), Marseille (France); Wang, Xin; Li, Haida; Ma, Yongge [Beijing Normal University, Department of Physics, Beijing (China)

    2017-11-15

    The post-Newtonian formulation of a general class of f(R) theories is set up in a third-order approximation. It turns out that the information of a specific form of f(R) gravity is encoded in the Yukawa potential, which is contained in the perturbative expansion of the metric components. Although the Yukawa potential is canceled in the second-order expression of the effective refraction index of light, detailed analysis shows that the difference of the lensing effect between the f(R) gravity and general relativity does appear at the third order when √(f''(0)/f{sup '}(0)) is larger than the distance d{sub 0} to the gravitational source. However, the difference between these two kinds of theories will disappear in the axially symmetric spacetime region. Therefore only in very rare case the f(R) theories are distinguishable from general relativity by gravitational lensing effect in a third-order post-Newtonian approximation. (orig.)

  3. 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

  4. 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.

  5. 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

  6. 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.

  7. Mean square number fluctuation for a fermion source and its ...

    Indian Academy of Sciences (India)

    Using the general formulation for obtaining chemical potential of an ideal Fermi gas of particles at temperature , with particle rest mass m 0 and average density ⟨ N ⟩ / V , the dependence of the mean square number fluctuation ⟨ N 2 ⟩ / V on the particle mass m 0 has been calculated explicitly. The numerical ...

  8. Single-shot fluctuations in waveguided high-harmonic generation

    NARCIS (Netherlands)

    Goh, S.J.; Tao, Y.; van der Slot, Petrus J.M.; Bastiaens, Hubertus M.J.; Herek, Jennifer Lynn; Biedron, S.G.; Danailov, M.B.; Milton, S.V.; Boller, Klaus J.

    2015-01-01

    For exploring the application potential of coherent soft x-ray (SXR) and extreme ultraviolet radiation (XUV) provided by high-harmonic generation, it is important to characterize the central output parameters. Of specific importance are pulse-to-pulse (shot-to-shot) fluctuations of the high-harmonic

  9. Fluctuation theorems and orbital magnetism in nonequilibrium state

    Indian Academy of Sciences (India)

    We study Langevin dynamics of a driven charged particle in the presence as well as in the absence of magnetic field. We discuss the validity of various work fluctuation theorems using different model potentials and external drives. We also show that one can generate an orbital magnetic moment in a nonequilibrium state ...

  10. A search for z= 7.3 Lyα emitters behind gravitationally lensing clusters

    Science.gov (United States)

    Ota, Kazuaki; Richard, Johan; Iye, Masanori; Shibuya, Takatoshi; Egami, Eiichi; Kashikawa, Nobunari

    2012-07-01

    We searched for z= 7.3 Lyα emitters (LAEs) behind two gravitationally lensing clusters, Abell 2390 and CL 0024, using the Subaru Telescope Suprime-Cam and a narrow-band filter NB1006 (λc˜ 1005 nm and full width at half-maximum of about 21 nm). The combination of the fully depleted CCDs of the Suprime-Cam, sensitive to z˜ 7 Lyα emission at ˜ 1 μm, and the magnification by the lensing clusters can be potentially a powerful tool to detect faint distant LAEs. Using the NB1006 and deep optical to mid-infrared images of the clusters taken with the Hubble Space Telescope and Spitzer Space Telescope, we investigated if there exist objects consistent with the colour of z= 7.3 LAEs behind the clusters. We could not detect any LAEs to the unlensed Lyα line flux limit of FLyα≃ 6.9 × 10-18 erg s-1 cm-2. Using several z=7 Lyα luminosity functions (LFs) from the literature, we estimated and compared the expected detection numbers of z˜ 7$ LAEs in lensing and blank field surveys in the case of using an 8-m class ground-based telescope. Given the steep bright-end slope of the LFs, when the detector field of view (FOV) is comparable to the angular extent of a massive lensing cluster, imaging cluster(s) is (are) more efficient in detecting z˜ 7 LAEs than imaging a blank field. However, the gain is expected to be modest, a factor of 2 at most and likely much less depending on the adopted LFs. The main advantage of lensing survey, therefore, remains the gain in depth and not necessarily in detection efficiency. For much larger detectors, the lensing effect becomes negligible and the efficiency of LAE detection is proportional to the instrumental FOV. We also investigated the NB1006 images of the three z˜ 7 z-dropout galaxy candidates previously detected in Abell 2390 and found that none of them is detected in NB1006. Two of them are consistent with the predictions from previous studies that they would be at lower redshifts. The other one has a photometric redshift of z

  11. Critical swelling of fluctuating capsules

    Science.gov (United States)

    Diamant, Haim; Haleva, Emir

    2009-03-01

    In many natural transport processes the solute molecules to be transported are encapsulated in semipermeable, flexible membrane vesicles of micron size. We study the swelling of such fluctuating capsules, as the number of encapsulated particles is increased, or the concentration of the outer solution is decreased. The approach to the maximum volume-to-area ratio and the associated buildup of membrane tension involve a continuous phase transition and follow universal scaling laws. The criticality and its features are model-independent, arising solely from the interplay between volume and surface degrees of freedom.ootnotetextE. Haleva and H. Diamant, Phys. Rev. Lett. 101, 078104 (2008).

  12. Noise and fluctuations an introduction

    CERN Document Server

    MacDonald, D K C

    2006-01-01

    An understanding of fluctuations and their role is both useful and fundamental to the study of physics. This concise study of random processes offers graduate students and research physicists a survey that encompasses both the relationship of Brownian Movement with statistical mechanics and the problem of irreversible processes. It outlines the basics of the physics involved, without the strictures of mathematical rigor.The three-part treatment starts with a general survey of Brownian Movement, including electrical Brownian Movement and ""shot-noise,"" Part two explores correlation, frequency

  13. Fluctuations in Overlapping Generations Economies

    DEFF Research Database (Denmark)

    Tvede, Mich

    In the present paper stationary pure-exchange overlapping generations economies with l  goods per date and m consumers per generation are considered. It is shown that for an open and dense set of utility functions there exist endowment vectors such that n-cycles exist for n = l +1 and l  = m....... The approach to existence of endogenous fluctuations is basic in the sense that the prime ingredients are the implicit function theorem and linear algebra. Moreover the approach is applied to show that for an open and dense set of utility functions there exist endowment vectors such that sunspot equilibria...

  14. An Objective Fluctuation Score for Parkinson's Disease

    Science.gov (United States)

    Horne, Malcolm K.; McGregor, Sarah; Bergquist, Filip

    2015-01-01

    Introduction Establishing the presence and severity of fluctuations is important in managing Parkinson’s Disease yet there is no reliable, objective means of doing this. In this study we have evaluated a Fluctuation Score derived from variations in dyskinesia and bradykinesia scores produced by an accelerometry based system. Methods The Fluctuation Score was produced by summing the interquartile range of bradykinesia scores and dyskinesia scores produced every 2 minutes between 0900-1800 for at least 6 days by the accelerometry based system and expressing it as an algorithm. Results This Score could distinguish between fluctuating and non-fluctuating patients with high sensitivity and selectivity and was significant lower following activation of deep brain stimulators. The scores following deep brain stimulation lay in a band just above the score separating fluctuators from non-fluctuators, suggesting a range representing adequate motor control. When compared with control subjects the score of newly diagnosed patients show a loss of fluctuation with onset of PD. The score was calculated in subjects whose duration of disease was known and this showed that newly diagnosed patients soon develop higher scores which either fall under or within the range representing adequate motor control or instead go on to develop more severe fluctuations. Conclusion The Fluctuation Score described here promises to be a useful tool for identifying patients whose fluctuations are progressing and may require therapeutic changes. It also shows promise as a useful research tool. Further studies are required to more accurately identify therapeutic targets and ranges. PMID:25928634

  15. Zero sound and spin fluctuations in liquid helium-3

    International Nuclear Information System (INIS)

    Aldrich, C.H. III; Pethick, C.J.; Pines, D.

    1976-01-01

    The density fluctuation spectrum of 3 He is calculated using a generalized polarization potential approach and shown to yield both zero sound and quasiparticle spectra in good agreement with the recent neutron scattering experiments. Landau Fermi-liquid theory is used to calculate the spin density fluctuation spectrum; and sum-rule arguments are presented which enable us to establish the qualitative nature of this spectrum at larger wave vectors with results in good qualitative agreement with the recent experiment of Skold et al

  16. Study of thermal - hydraulic sensors signal fluctuations in PWR

    International Nuclear Information System (INIS)

    Hennion, F.

    1987-10-01

    This thesis deals with signal fluctuations of thermal-hydraulic sensors in the main coolant primary of a pressurized water reactor. The aim of this work is to give a first response about the potentiality of use of these noise signals for the functionning monitoring. Two aspects have been studied: - the modelisation of temperature fluctuations of core thermocouples, by a Monte-Carlo method, gives the main characteristics of these signals and their domain of application. - the determination of eigenfrequency in the primary by an acoustic representation could permit the monitoring of local and global thermo-hydraulic conditions [fr

  17. Entropic fluctuations in DNA sequences

    Science.gov (United States)

    Thanos, Dimitrios; Li, Wentian; Provata, Astero

    2018-03-01

    The Local Shannon Entropy (LSE) in blocks is used as a complexity measure to study the information fluctuations along DNA sequences. The LSE of a DNA block maps the local base arrangement information to a single numerical value. It is shown that despite this reduction of information, LSE allows to extract meaningful information related to the detection of repetitive sequences in whole chromosomes and is useful in finding evolutionary differences between organisms. More specifically, large regions of tandem repeats, such as centromeres, can be detected based on their low LSE fluctuations along the chromosome. Furthermore, an empirical investigation of the appropriate block sizes is provided and the relationship of LSE properties with the structure of the underlying repetitive units is revealed by using both computational and mathematical methods. Sequence similarity between the genomic DNA of closely related species also leads to similar LSE values at the orthologous regions. As an application, the LSE covariance function is used to measure the evolutionary distance between several primate genomes.

  18. Solidity of viscous liquids. IV. Density fluctuations

    DEFF Research Database (Denmark)

    Dyre, J. C.

    2006-01-01

    This paper is the fourth in a series exploring the physical consequences of the solidity of highly viscous liquids. It is argued that the two basic characteristics of a flow event (a jump between two energy minima in configuration space) are the local density change and the sum of all particle...... with Debye behavior at low frequencies and an omega^{−1/2} decay of the loss at high frequencies. Finally, a general formalism for the description of viscous liquid dynamics, which supplements the density dynamics by including stress fields, a potential energy field, and molecular orientational fields...... displacements. Based on this it is proposed that density fluctuations are described by a time-dependent Ginzburg-Landau equation with rates in k space of the form C+Dk^2 with D>>C a^2 where a is the average intermolecular distance. The inequality expresses a long-wavelength dominance of the dynamics which...

  19. Voltage fluctuations in neurons: signal or noise?

    DEFF Research Database (Denmark)

    Yarom, Yosef; Hounsgaard, Jorn

    2011-01-01

    that allows and facilitates complex adaptive behavior in an unpredictable world. Here we review the growing experimental evidence that functional network activity is associated with intense fluctuations in membrane potential and spike timing. We trace origins and consequences of noise and variability. Finally......, we discuss noise-free neuronal signaling and detrimental and beneficial forms of noise in large-scale functional neural networks. Evidence that noise and variability in some cases go hand in hand with behavioral variability and increase behavioral choice, richness, and adaptability opens new avenues......Noise and variability are fundamental companions to ion channels and synapses and thus inescapable elements of brain function. The overriding unresolved issue is to what extent noise distorts and limits signaling on one hand and at the same time constitutes a crucial and fundamental enrichment...

  20. The origin of density fluctuations in the 'new inflationary universe'

    Science.gov (United States)

    Turner, M. S.

    1983-01-01

    Cosmological mysteries which are not explained by the Big Bang hypothesis but may be approached by a revamped inflationary universe model are discussed. Attention is focused on the isotropy, the large-scale homogeneity, small-scale inhomogeneity, the oldness/flatness of the universe, and the baryon asymmetry. The universe is assumed to start in the lowest energy state, be initially dominated by false vacuum energy, enter a de Sitter phase, and then cross a barrier which is followed by the formation of fluctuation regions that lead to structure. The scalar fields (perturbation regions) experience quantum fluctuations which produce spontaneous symmetry breaking on a large scale. The scalar field value would need to be much greater than the expansion rate during the de Sitter epoch. A supersymmetric (flat) potential which satisfies the requirement, yields fluctuations of the right magnitude, and allows inflation to occur is described.

  1. Effect of subthalamic deep brain stimulation on non-motor fluctuations in Parkinson's disease.

    Science.gov (United States)

    Azulay, Jean-Philippe; Witjas, Tatiana; Eusebio, Alexandre

    2013-04-01

    The non-motor consequences of subthalamic stimulation are largely questioned. Cognition, motivation, anxiety, depression and even occurrence of suicides have been considered as a potential consequence of the surgical intervention. Non-motor fluctuations are present in all the patients with motor fluctuations and may sometimes be even more invalidating. Interestingly, subthalamic deep brain stimulation alleviates non-motor fluctuations allowing strikingly successful effects on sensory, dysautonomic and cognitive fluctuations while psychic fluctuations respond less consistently to this treatment. Nevertheless, severe mood fluctuations, oscillating from Off dysphoria to ON hypomania, are frequently associated with addictive behaviors and improve dramatically after subthalamic stimulation. This may be a further argument to support the indication of surgery for these patients.

  2. Dark Energy Survey Year 1 Results: Curved-Sky Weak Lensing Mass Map

    Energy Technology Data Exchange (ETDEWEB)

    Chang, C.; et al.

    2017-08-04

    We construct the largest curved-sky galaxy weak lensing mass map to date from the DES first-year (DES Y1) data. The map, about 10 times larger than previous work, is constructed over a contiguous $\\approx1,500 $deg$^2$, covering a comoving volume of $\\approx10 $Gpc$^3$. The effects of masking, sampling, and noise are tested using simulations. We generate weak lensing maps from two DES Y1 shear catalogs, Metacalibration and Im3shape, with sources at redshift $0.2potential systematic contaminants. Finally, we demonstrate two applications of the mass maps: (1) cross-correlation with different foreground tracers of mass and (2) exploration of the largest peaks and voids in the maps.

  3. Ultraviolet radiation at Mediterranean latitudes and protection efficacy of intraocular lenses.

    Science.gov (United States)

    Artigas, J M; Felipe, A; Navea, A; Artigas, C; Menezo, J L

    2013-01-01

    After determining the mean intensity of ultraviolet radiation to which the human eye is exposed at Mediterranean latitudes, this data is used to evaluate the efficacy of the ultraviolet filters incorporated into various intraocular lenses. Ultraviolet radiation measured at Mediterranean latitudes was used as a reference for the theoretical calculation of the amount of radiation to which the human eye is exposed. The spectral transmission curve from 290 to 380 nm was measured for 10 IOLs using a UV/VIS Perkins-Elmer Lambda 800 spectrometer. At Mediterranean latitudes, at sea level, with a mean annual solar irradiation of 50 j/cm(2), the human eye receives a quantity of UVA and UVB that is lower than the threshold toxic dose for the rabbit crystalline lens (93 j/cm(2) for UVA and 6.45 j/cm(2) for UVB). However, at higher altitudes and with albedo approaching 0.9 (fresh snow), the amount of radiation increases, with duration of exposure potentially playing a significant role. The UV filters incorporated into the IOLs studied are, in general, protective against such levels of radiation. At Mediterranean latitudes, at sea level, the amount of UV radiation to which our eyes are exposed is insufficient to damage the crystalline lens; however, at higher altitudes, the risk of such damage exists. UV filters incorporated into intraocular lenses are generally effective, since they filter all radiation with wavelengths under 380 nm. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

  4. 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.

  5. Confirmation of general relativity on large scales from weak lensing and galaxy velocities.

    Science.gov (United States)

    Reyes, Reinabelle; Mandelbaum, Rachel; Seljak, Uros; Baldauf, Tobias; Gunn, James E; Lombriser, Lucas; Smith, Robert E

    2010-03-11

    Although general relativity underlies modern cosmology, its applicability on cosmological length scales has yet to be stringently tested. Such a test has recently been proposed, using a quantity, E(G), that combines measures of large-scale gravitational lensing, galaxy clustering and structure growth rate. The combination is insensitive to 'galaxy bias' (the difference between the clustering of visible galaxies and invisible dark matter) and is thus robust to the uncertainty in this parameter. Modified theories of gravity generally predict values of E(G) different from the general relativistic prediction because, in these theories, the 'gravitational slip' (the difference between the two potentials that describe perturbations in the gravitational metric) is non-zero, which leads to changes in the growth of structure and the strength of the gravitational lensing effect. Here we report that E(G) = 0.39 +/- 0.06 on length scales of tens of megaparsecs, in agreement with the general relativistic prediction of E(G) approximately 0.4. The measured value excludes a model within the tensor-vector-scalar gravity theory, which modifies both Newtonian and Einstein gravity. However, the relatively large uncertainty still permits models within f(R) theory, which is an extension of general relativity. A fivefold decrease in uncertainty is needed to rule out these models.

  6. Pulsed Neutron Scattering Studies of Strongly Fluctuating solids, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Collin Broholm

    2006-06-22

    The conventional description of a solid is based on a static atomic structure with small amplitude so-called harmonic fluctuations about it. This is a final technical report for a project that has explored materials where fluctuations are sufficiently strong to severely challenge this approach and lead to unexpected and potentially useful materials properties. Fluctuations are enhanced when a large number of configurations share the same energy. We used pulsed spallation source neutron scattering to obtain detailed microscopic information about structure and fluctuations in such materials. The results enhance our understanding of strongly fluctuating solids and their potential for technical applications. Because new materials require new experimental techniques, the project has also developed new techniques for probing strongly fluctuating solids. Examples of material that were studied are ZrW2O8 with large amplitude molecular motion that leads to negative thermal expansion, NiGa2S4 where competing interactions lead to an anomalous short range ordered magnet, Pr1- xBixRu2O7 where a partially filled electron shell (Pr) in a weakly disordered environment produces anomalous metallic properties, and TbMnO3 where competing interactions lead to a magneto-electric phase. The experiments on TbMnO3 exemplify the relationship between research funded by this project and future applications. Magneto-electric materials may produce a magnetic field when an electric field is applied or vise versa. Our experiments have clarified the reason why electric and magnetic polarization is coupled in TbMnO3. While this knowledge does not render TbMnO3 useful for applications it will focus the search for a practical room temperature magneto-electric for applications.

  7. 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

  8. Hydrodynamical fluctuations in smooth shear flows

    International Nuclear Information System (INIS)

    Chagelishvili, G.D.; Khujadze, G.R.; Lominadze, J.G.

    1999-11-01

    Background of hydrodynamical fluctuations in a intrinsically/stochastically forced, laminar, uniform shear flow is studied. The employment of so-called nonmodal mathematical analysis makes it possible to represent the background of fluctuations in a new light and to get more insight into the physics of its formation. The basic physical processes responsible for the formation of vortex and acoustic wave fluctuation backgrounds are analyzed. Interplay of the processes at low and moderate shear rates is described. Three-dimensional vortex fluctuations around a given macroscopic state are numerically calculated. The correlation functions of the fluctuations of physical quantities are analyzed. It is shown that there exists subspace D k in the wave-number space (k-space) that is limited externally by spherical surface with radius k ν ≡ A/ν (where A is the velocity shear parameter, ν - the kinematic viscosity) in the nonequilibrium open system under study. The spatial Fourier harmonics of vortex as well as acoustic wave fluctuations are strongly subjected by flow shear (by the open character of the system) at wave-numbers satisfying the condition k ν . Specifically it is shown that in D k : The fluctuations are non-Markovian; the spatial spectral density of energy of the vortex fluctuations by far exceeds the white-noise; the term of a new type associated to the hydrodynamical fluctuation of velocity appears in the correlation function of pressure; the fluctuation background of the acoustic waves is completely different at low and moderate shear rates (at low shear rates it is reduced in D k in comparison to the uniform (non-shear) flow; at moderate shear rates it it comparable to the background of the vortex fluctuations). The fluctuation background of both the vortex and the acoustic wave modes is anisotropic. The possible significance of the fluctuation background of vortices for the subcritical transition to turbulence and Brownian motion of small macroscopic

  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. 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

  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. 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.

  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. 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.

  19. 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

  20. 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...

  1. 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.

  2. 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.

  3. Bet Hedging against Demographic Fluctuations

    Science.gov (United States)

    Xue, BingKan; Leibler, Stanislas

    2017-09-01

    Biological organisms have to cope with stochastic variations in both the external environment and the internal population dynamics. Theoretical studies and laboratory experiments suggest that population diversification could be an effective bet-hedging strategy for adaptation to varying environments. Here we show that bet hedging can also be effective against demographic fluctuations that pose a trade-off between growth and survival for populations even in a constant environment. A species can maximize its overall abundance in the long term by diversifying into coexisting subpopulations of both "fast-growing" and "better-surviving" individuals. Our model generalizes statistical physics models of birth-death processes to incorporate dispersal, during which new populations are founded, and can further incorporate variations of local environments. In this way, we unify different bet-hedging strategies against demographic and environmental variations as a general means of adaptation to both types of uncertainties in population growth.

  4. Characterizing flow fluctuations with moments

    Directory of Open Access Journals (Sweden)

    Rajeev S. Bhalerao

    2015-03-01

    Full Text Available We present a complete set of multiparticle correlation observables for ultrarelativistic heavy-ion collisions. These include moments of the distribution of the anisotropic flow in a single harmonic and also mixed moments, which contain the information on correlations between event planes of different harmonics. We explain how all these moments can be measured using just two symmetric subevents separated by a rapidity gap. This presents a multi-pronged probe of the physics of flow fluctuations. For instance, it allows to test the hypothesis that event-plane correlations are generated by non-linear hydrodynamic response. We illustrate the method with simulations of events in A MultiPhase Transport (AMPT model.

  5. Fluctuating nonlinear hydrodynamics of flocking

    Science.gov (United States)

    Yadav, Sunil Kumar; Das, Shankar P.

    2018-03-01

    Starting from a microscopic model, the continuum field theoretic description of the dynamics of a system of active ingredients or "particles" is presented. The equations of motion for the respective collective densities of mass and momentum follow exactly from that of a single element in the flock. The single-particle dynamics has noise and anomalous momentum dependence in its frictional terms. The equations for the collective densities are averaged over a local equilibrium distribution to obtain the corresponding coarse grained equations of fluctuating nonlinear hydrodynamics (FNH). The latter are the equations used frequently for describing active systems on the basis of intuitive arguments. The transport coefficients which appear in the macroscopic FNH equations are determined in terms of the parameters of the microscopic dynamics.

  6. Discovery of two gravitationally lensed quasars with image separations of 3 arcseconds from the Sloan Digital Sky Survey

    Energy Technology Data Exchange (ETDEWEB)

    Oguri, Masamune; Inada, Naohisa; Hennawi, Joseph F.; Richards, Gordon T.; Johnston, David E.; Frieman, Joshua A.; Pindor, Bartosz; Strauss, Michael A.; Brunner, Robert; Becker, Robert H.; Castander, Francisco J.; Gregg, Michael D.; Hall, Patrick B.; Rix, Hans-Walter; Schneider, Donald P.; Bahcall, Neta A.; Brinkmann, Jonathan; York, Donald G.

    2004-11-01

    We report the discovery of two doubly-imaged quasars, SDSS J100128.61+502756.9 and SDSS J120629.65+433217.6, at redshifts of 1.838 and 1.789 and with image separations of 2.86'' and 2.90'', respectively. The objects were selected as lens candidates from the Sloan Digital Sky Survey (SDSS). Based on the identical nature of the spectra of the two quasars in each pair and the identification of the lens galaxies, we conclude that the objects are gravitational lenses. The lenses are complicated; in both systems there are several galaxies in the fields very close to the quasars, in addition to the lens galaxies themselves. The lens modeling implies that these nearby galaxies contribute significantly to the lens potentials. On larger scales, we have detected an enhancement in the galaxy density near SDSS J100128.61+502756.9. The number of lenses with image separation of {approx} 3'' in the SDSS already exceeds the prediction of simple theoretical models based on the standard Lambda-dominated cosmology and observed velocity function of galaxies.

  7. Testing dark matter halos using rotation curves and lensing: A warning on the determination of the halo mass

    International Nuclear Information System (INIS)

    Nunez, Dario; Gonzalez-Morales, Alma X.; Cervantes-Cota, Jorge L.; Matos, Tonatiuh

    2010-01-01

    There are two observations of galaxies that can offer some insight into the nature of dark matter (DM), namely, the rotation curves and the gravitational lensing. While the first one can be studied using the Newtonian limit, the second one is completely relativistic. Each one separately cannot determine the nature of DM, but both together give us key information about this open problem. In this work we use a static and spherically symmetric metric to model the DM halo in a galaxy or in a galaxy cluster. The metric contains two free functions, one associated with the distribution of mass and the other one with the gravitational potential. We use galactic, typical rotation curves to uniquely determine the kinematics of the halos. We compute separately the mass functions for a perfect fluid and a scalar field, and demonstrate that both models can be fitted to the observations, though with different masses. We then employ lensing to discriminate between these models. This procedure represents a test of models using two measurements: rotation curves and lensing.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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

  13. 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.

  14. 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

  15. 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.

  16. 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)

  17. The use of contact lenses among university students in Chengdu: Knowledge and practice of contact lens wearers.

    Science.gov (United States)

    Zhu, Qiurong; Yang, Bi; Deng, Nan; Li, Yifan; Wang, Tingwei; Qi, Huang; Liu, Longqian

    2018-04-01

    To assess the prevalence and general knowledge of contact lens wearers among college students in Chengdu, a metroplolitan of Chinaand find out the routine habits of use and hygienic conditions when wearing contact lenses. The questionnaire was distributed to 1,600 ametropic participants who were from 8 different universities. Data about demographics, general contact lens handling habits, personal attitudes, hygiene behaviors and eye health conditions were collected. We made the analysis ofthe demographics and wearing of contact lenses. Possible reasons for behaviors related to the care of contact lenses were analyzed. The prevalence of contact lens use was 19.80%. Most users (82.15%) were females. An aesthetic effect was cited as the first reason for using (57.91%). The comfort of eyes was the first consideration (75.76%) when buying. To keep clean and use safe, 86.20% subjects washed hands before handling and 83.50% cleaned the lens carefully after removing. There was significant difference between males and females regarding the replacement of the solution (p=0.014). 32.66% wears knew the removal of protein deposits. A total of 54.88% were not informed of the potential complications of contact lens. The incidence of ocular discomfort was 44.78%. Only 3.03% of the students paid regular visits to ophthalmic clinics. The prevalence of contact lenses was relatively low in Chengdu. The wears had limited knowledge about using and careof contact lens. More education on standard lens wear and care should be provided to wearers. Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.

  18. Interplanetary Alfvenic fluctuations: A stochastic model

    International Nuclear Information System (INIS)

    Barnes, A.

    1981-01-01

    The strong alignment of the average directions of minimum magnetic variance and mean magnetic field in interplanetary Alfvenic fluctuations is inconsistent with the usual wave-propagation models. We investigate the concept of minimum variance for nonplanar Alfvenic fluctuations in which the field direction varies stochastically. It is found that the tendency of the minimum variance and mean field directions to be aligned may be purely a consequence of the randomness of the field direction. In particular, a well-defined direction of minimum variance does not imply that the fluctuations are necessarily planar. The fluctuation power spectrum is a power law for frequencies much higher than the inverse of the correlation time. The probability distribution of directions a randomly fluctuating field of constant magnitude is calculated. A new approach for observational studies of interplanetary fluctuations is suggested

  19. Integral fluctuation theorems for stochastic resetting systems

    Science.gov (United States)

    Pal, Arnab; Rahav, Saar

    2017-12-01

    We study the stochastic thermodynamics of resetting systems. Violation of microreversibility means that the well-known derivations of fluctuations theorems break down for dynamics with resetting. Despite that we show that stochastic resetting systems satisfy two integral fluctuation theorems. The first is the Hatano-Sasa relation describing the transition between two steady states. The second integral fluctuation theorem involves a functional that includes both dynamical and thermodynamic contributions. We find that the second law-like inequality found by Fuchs et al. for resetting systems [Europhys. Lett. 113, 60009 (2016), 10.1209/0295-5075/113/60009] can be recovered from this integral fluctuation theorem with the help of Jensen's inequality.

  20. Fluctuations in percolation of sparse complex networks

    Science.gov (United States)

    Bianconi, Ginestra

    2017-07-01

    We study the role of fluctuations in percolation of sparse complex networks. To this end we consider two random correlated realizations of the initial damage of the nodes and we evaluate the fraction of nodes that are expected to remain in the giant component of the network in both cases or just in one case. Our framework includes a message-passing algorithm able to predict the fluctuations in a single network, and an analytic prediction of the expected fluctuations in ensembles of sparse networks. This approach is applied to real ecological and infrastructure networks and it is shown to characterize the expected fluctuations in their response to external damage.

  1. Neutrino propagation in a fluctuating sun

    International Nuclear Information System (INIS)

    Burgess, C.P.; Michaud, D.

    1997-01-01

    We adapt to neutrino physics a general formulation for particle propagation in fluctuating media, initially developed for applications to electromagnetism and neutron optics. In leading approximation this formalism leads to the usual MSW effective Hamiltonian governing neutrino propagation through a medium. Next-to-leading contributions describe deviations from this description, which arise due to neutrino interactions with fluctuations in the medium. We compute these corrections for two types of fluctuations: (i) microscopic thermal fluctuations and (ii) macroscopic fluctuations in the medium s density. While the first of these reproduces standard estimates, which are negligible for applications to solar neutrinos, we find that the second can be quite large, since it grows in size with the correlation length of the fluctuation. We consider two models in some detail. For fluctuations whose correlations extend only over a local region in space of length l, appreciable effects for MSW oscillations arise if (δn/n) 2 l approx-gt 100m or so. Alternatively, a crude model of helioseismic p-waves gives appreciable effects only when (δn/n)approx-gt 1%. In general the dominant effect is to diminish the quality of the resonance, making the suppression of the 7 Be neutrinos a good experimental probe of fluctuations deep within the sun. Fluctuations can also provide a new mechanism for reducing the solar neutrino flux, giving an energy-independent suppression factor of 1/2 away from the resonant region, even for small vacuum mixing angles. copyright 1997 Academic Press, Inc

  2. Quantum fluctuations within the fragmentation theory

    International Nuclear Information System (INIS)

    Maruhn, J.A.; Hahn, J.; Lustig, H.J.; Zeigenhain, K.H.; Greiner, W.

    1980-01-01

    The measured spread of the fragment mass distributions in heavy ion collisions may be due to two quite different physical mechanisms: the quantum-mechanical uncertainty associated with collective motion in the mass asymmetry degree of freedom, and the spread caused by thermal excitation of the nuclear system. The fluctuations in physical observables induced in these ways are referred to as quantum fluctuations and statistical fluctuations. In this lecture quantum fluctuations are studied within the fragmentation theory. Mass distributions for spontaneous fission and low energy heavy ion collisions are investigated. (author)

  3. 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

  4. 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

  5. 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

  6. 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

  7. 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.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. Short-term fluctuations in motivation to quit smoking in a sample of smokers in Hawaii.

    Science.gov (United States)

    Herzog, Thaddeus; Pokhrel, Pallav; Kawamoto, Crissy T

    2015-01-01

    Despite its potential for usefulness in informing the development of smoking cessation interventions, short-term fluctuations in motivation to quit is a relatively understudied topic. To assess the prevalence of smokers' day-to-day fluctuations in motivation to quit, and to assess associations of day-to-day fluctuations in motivation to quit with several established cessation-related variables. A cross-sectional survey was administered to smokers in Hawaii (N = 1,567). To assess short-term fluctuations in motivation to quit smoking, participants were asked to respond "True" or "False" to the statement: "My motivation to quit smoking changes from one day to the next." Other items measured desire to quit smoking, intention to quit, confidence in quitting, cigarette dependence, and other cessation-related variables. "My motivation to quit smoking changes from one day to the next" was endorsed as true by 64.7% of smokers, and false by 35.3%. Analyses revealed that smokers who indicated fluctuating motivation were significantly more interested in quitting as compared to smokers without fluctuations. Fluctuations in motivation to quit also were associated with greater confidence in quitting, lesser cigarette dependence, and more recent quitting activity (all p < .01). Day-to-day fluctuations in motivation to quit are common. Day-to-day fluctuations in motivation to quit are strongly associated with higher motivation to quit, greater confidence in future quitting, and other positive cessation-relevant trends.

  13. 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 ...

  14. 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 ...

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. Fluctuations of offshore wind generation: Statistical modelling

    DEFF Research Database (Denmark)

    Pinson, Pierre; Christensen, Lasse E.A.; Madsen, Henrik

    2007-01-01

    The magnitude of power fluctuations at large offshore wind farms has a significant impact on the control and management strategies of their power output. If focusing on the minute scale, one observes successive periods with smaller and larger power fluctuations. It seems that different regimes yi...

  20. Dynamical interplay between fluctuations, electric fields and ...

    Indian Academy of Sciences (India)

    interplay between fluctuation in gradients, turbulent transport and radial electric fields has shown that these parameters ... electric fields and density fluctuations, ΓE¢B(t) = ˜n(t) ˜Eθ (t)/B. The poloidal electric field has been .... transport increases and the system performs a relaxation which tends to drive the plasma back to the ...