WorldWideScience

Sample records for range front light

  1. Light-Front QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, S.

    2004-11-30

    In these lectures, I survey a number of applications of light-front methods to hadron and nuclear physics phenomenology and dynamics, including light-front statistical physics. Light-front Fock-state wavefunctions provide a frame-independent representation of hadrons in terms of their fundamental quark and gluon degrees of freedom. Nonperturbative methods for computing LFWFs in QCD are discussed, including string/gauge duality which predicts the power-law fall-off at high momentum transfer of light-front Fock-state hadronic wavefunctions with an arbitrary number of constituents and orbital angular momentum. The AdS/CFT correspondence has important implications for hadron phenomenology in the conformal limit, including an all-orders derivation of counting rules for exclusive processes. One can also compute the hadronic spectrum of near-conformal QCD assuming a truncated AdS/CFT space. Given the LFWFs, one can compute form factors, heavy hadron decay amplitudes, hadron distribution amplitudes, and the generalized parton distributions underlying deeply virtual Compton scattering. The quantum fluctuations represented by the light-front Fock expansion leads to novel QCD phenomena such as color transparency, intrinsic heavy quark distributions, diffractive dissociation, and hidden-color components of nuclear wavefunctions. A new test of hidden color in deuteron photodisintegration is proposed. The origin of leading-twist phenomena such as the diffractive component of deep inelastic scattering, single-spin asymmetries, nuclear shadowing and antishadowing is also discussed; these phenomena cannot be described by light-front wavefunctions of the target computed in isolation. Part of the anomalous NuTeV results for the weak mixing angle {theta}{sub W} could be due to the non-universality of nuclear antishadowing for charged and neutral currents.

  2. Chiral symmetry in light-front QCD

    Science.gov (United States)

    Wu, Menh-Hsiu; Zhang, Wei-Min

    2004-04-01

    The definition of chiral transformations in light-front field theory is very different from the conventional form in equal-time formalism. We study the consistency of chiral transformations and chiral symmetry in light-front QCD and derive a complete new light-front axial-vector current for QCD. The breaking of chiral symmetry in light-front QCD is only associated with helicity flip interaction between quarks and gluons. Remarkably, the new axial-vector current does not contain the pion pole part so that the associate chiral charge smoothly describes pion transitions for various hadronic processes.

  3. Chiral Symmetry in Light-front QCD

    OpenAIRE

    Wu, Meng-Hsiu; Zhang, Wei-Min

    2003-01-01

    The definition of chiral transformations in light-front field theory is very different from the conventional form in equal-time formalism. We study the consistency of chiral transformations and chiral symmetry in light-front QCD and derive a complete new light-front axial-vector current for QCD. The breaking of chiral symmetry in light-front QCD is only associated with helicity flip interaction between quarks and gluons. Remarkably, the new axial-vector current does not contain the pion pole ...

  4. The light-front vacuum and dynamics

    OpenAIRE

    Polyzou, W. N.

    2004-01-01

    I give a quantum theoretical description of kinematically invariant vacuua on the algebra of free fields restricted to a light front and discuss the relation between the light-front Hamiltonian, P-, the vacuum, and Poincare invariance. This provides a quantum theoretical description of zero modes.

  5. Light front quantum chromodynamics: Towards phenomenology

    Indian Academy of Sciences (India)

    We briefly review the application of light front QCD to inclusive deep inelastic scattering. Keywords. Light front dynamics .... longitudinal gluon structure function and to a new sum rule. К. dmFД/m = 4M¾/Q¾. , which ... For the transversely polarized structure function g¾, if the twist three contributions are ignored, one gets an ...

  6. Light front distribution of the chiral condensate

    National Research Council Canada - National Science Library

    Chang, Lei; Roberts, Craig D; Schmidt, Sebastian M

    2013-01-01

    The pseudoscalar projection of the pionE1/4s Poincare-covariant Bethe-Salpeter amplitude onto the light-front may be understood to provide the probability distribution of the chiral condensate within the pion...

  7. QCD and Light-Front Dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; de Teramond, Guy F.; /SLAC /Southern Denmark U., CP3-Origins /Costa Rica U.

    2011-01-10

    AdS/QCD, the correspondence between theories in a dilaton-modified five-dimensional anti-de Sitter space and confining field theories in physical space-time, provides a remarkable semiclassical model for hadron physics. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The result is a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. The hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. Higher Fock states with extra quark-anti quark pairs also arise. The soft-wall model also predicts the form of the nonperturbative effective coupling and its {beta}-function. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method to systematically include QCD interaction terms. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.

  8. Light-Front Holography and the Light-Front Schrodinger Equation

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; de Teramond, Guy

    2012-08-15

    One of the most important nonperturbative methods for solving QCD is quantization at fixed light-front time {tau} = t+z=c - Dirac's 'Front Form'. The eigenvalues of the light-front QCD Hamiltonian predict the hadron spectrum and the eigensolutions provide the light-front wavefunctions which describe hadron structure. More generally, we show that the valence Fock-state wavefunctions of the light-front QCD Hamiltonian satisfy a single-variable relativistic equation of motion, analogous to the nonrelativistic radial Schrodinger equation, with an effective confining potential U which systematically incorporates the effects of higher quark and gluon Fock states. We outline a method for computing the required potential from first principles in QCD. The holographic mapping of gravity in AdS space to QCD, quantized at fixed light-front time, yields the same light front Schrodinger equation; in fact, the soft-wall AdS/QCD approach provides a model for the light-front potential which is color-confining and reproduces well the light-hadron spectrum. One also derives via light-front holography a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. The elastic and transition form factors of the pion and the nucleons are found to be well described in this framework. The light-front AdS/QCD holographic approach thus gives a frame-independent first approximation of the color-confining dynamics, spectroscopy, and excitation spectra of relativistic light-quark bound states in QCD.

  9. QCD Phenomenology and Light-Front Wavefunctions

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.

    2001-11-21

    A natural calculus for describing the bound-state structure of relativistic composite systems in quantum field theory is the light-front Fock expansion which encodes the properties of a hadrons in terms of a set of frame-independent n-particle wavefunctions. Light-front quantization in the doubly-transverse light-cone gauge has a number of remarkable advantages, including explicit unitarity, a physical Fock expansion, the absence of ghost degrees of freedom, and the decoupling properties needed to prove factorization theorems in high momentum transfer inclusive and exclusive reactions. A number of applications are discussed in these lectures, including semileptonic B decays, two-photon exclusive reactions, diffractive dissociation into jets, and deeply virtual Compton scattering. The relation of the intrinsic sea to the light-front wavefunctions is discussed. Light-front quantization can also be used in the Hamiltonian form to construct an event generator for high energy physics reactions at the amplitude level. The light-cone partition function, summed over exponentially weighted light-cone energies, has simple boost properties which may be useful for studies in heavy ion collisions. I also review recent work which shows that the structure functions measured in deep inelastic lepton scattering are affected by final-state rescattering, thus modifying their connection to light-front probability distributions. In particular, the shadowing of nuclear structure functions is due to destructive interference effects from leading-twist diffraction of the virtual photon, physics not included in the nuclear light-cone wavefunctions.

  10. Light Detection And Ranging

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — LiDAR (Light Detection and Ranging) discrete-return point cloud data are available in the American Society for Photogrammetry and Remote Sensing (ASPRS) LAS format....

  11. QCD and Light-Front Holography

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.

    2010-10-27

    The soft-wall AdS/QCD model, modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics. The model predicts a zero-mass pion for zero-mass quarks and a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number N. Light-Front Holography maps the amplitudes which are functions of the fifth dimension variable z of anti-de Sitter space to a corresponding hadron theory quantized on the light front. The resulting Lorentz-invariant relativistic light-front wave equations are functions of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. The result is to a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryon light-quark bound states, which in turn predict the behavior of the pion and nucleon form factors. The theory implements chiral symmetry in a novel way: the effects of chiral symmetry breaking increase as one goes toward large interquark separation, consistent with spectroscopic data, and the the hadron eigenstates generally have components with different orbital angular momentum; e.g., the proton eigenstate in AdS/QCD with massless quarks has L = 0 and L = 1 light-front Fock components with equal probability. The soft-wall model also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q) and its {beta}-function which agrees with the effective coupling {alpha}{sub g1} extracted from the Bjorken sum rule. The AdS/QCD model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms. A new perspective on quark and gluon condensates is also reviewed.

  12. Light-Front Dynamics in Hadron Physics

    NARCIS (Netherlands)

    Ji, C.R.; Bakker, B.L.G.; Choi, H.M.

    2013-01-01

    Light-front dynamics(LFD) plays an important role in the analyses of relativistic few-body systems. As evidenced from the recent studies of generalized parton distributions (GPDs) in hadron physics, a natural framework for a detailed study of hadron structures is LFD due to its direct application in

  13. 76 FR 63656 - Front Range Resource Advisory Council Meeting Cancellation

    Science.gov (United States)

    2011-10-13

    ...] Front Range Resource Advisory Council Meeting Cancellation AGENCY: Bureau of Land Management, Interior... Front Range Resource Advisory Council meeting scheduled for October 19, 2011 at the BLM Royal Gorge....m. to 4:30 p.m. FOR FURTHER INFORMATION CONTACT: Tina Brown, Front Range RAC Coordinator, BLM...

  14. Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena

    DEFF Research Database (Denmark)

    Brodsky, S. J.; de Teramond, G. F.

    2012-01-01

    -classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryons. The model predicts a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number n. The hadron eigensolutions...... the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate zeta which measures the separation of the constituents within a hadron at equal light-front time and determines...

  15. Desirable forest structures for a restored Front Range

    Science.gov (United States)

    Yvette L. Dickinson; Rob Addington; Greg Aplet; Mike Babler; Mike Battaglia; Peter Brown; Tony Cheng; Casey Cooley; Dick Edwards; Jonas Feinstein; Paula Fornwalt; Hal Gibbs; Megan Matonis; Kristen Pelz; Claudia Regan

    2014-01-01

    As part of the federal Collaborative Forest Landscape Restoration Program administered by the US Forest Service, the Colorado Front Range Collaborative Forest Landscape Restoration Project (FR-CFLRP, a collaborative effort of the Front Range Roundtable1 and the US Forest Service) is required to define desired conditions for lower montane ponderosa pine (Pinus ponderosa...

  16. Novel Perspectives from Light-Front QCD, Super-Conformal Algebra, and Light-Front Holography

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-12-01

    Light-Front Quantization – Dirac’s “Front Form” – provides a physical, frame-independent formalism for hadron dynamics and structure. Observables such as structure functions, transverse momentum distributions, and distribution amplitudes are defined from the hadronic LFWFs. One obtains new insights into the hadronic mass scale, the hadronic spectrum, and the functional form of the QCD running coupling in the nonperturbative domain using light-front holography. In addition, superconformal algebra leads to remarkable supersymmetric relations between mesons and baryons. I also discuss evidence that the antishadowing of nuclear structure functions is nonuniversal; i.e., flavor dependent, and why shadowing and antishadowing phenomena may be incompatible with the momentum and other sum rules for the nuclear parton distribution functions.

  17. Light-Front Holography, Light-Front Wavefunctions, and Novel QCD Phenomena

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; de Teramond, Guy F.; /Costa Rica U.

    2012-02-16

    Light-Front Holography is one of the most remarkable features of the AdS/CFT correspondence. In spite of its present limitations it provides important physical insights into the nonperturbative regime of QCD and its transition to the perturbative domain. This novel framework allows hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time. The model leads to an effective confining light-front QCD Hamiltonian and a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time and determines the off-shell dynamics of the bound-state wavefunctions, and thus the fall-off as a function of the invariant mass of the constituents. The soft-wall holographic model modified by a positive-sign dilaton metric, leads to a remarkable one-parameter description of nonperturbative hadron dynamics - a semi-classical frame-independent first approximation to the spectra and light-front wavefunctions of meson and baryons. The model predicts a Regge spectrum of linear trajectories with the same slope in the leading orbital angular momentum L of hadrons and the radial quantum number n. The hadron eigensolutions projected on the free Fock basis provides the complete set of valence and non-valence light-front Fock state wavefunctions {Psi}{sub n/H} (x{sub i}, k{sub {perpendicular}i}, {lambda}{sub i}) which describe the hadron's momentum and spin distributions needed to compute the direct measures of hadron structure at the quark and gluon level, such as elastic and transition form factors, distribution amplitudes, structure functions, generalized parton distributions and transverse

  18. Light-front holography: a first approximation to QCD.

    Science.gov (United States)

    de Téramond, Guy F; Brodsky, Stanley J

    2009-02-27

    Starting from the Hamiltonian equation of motion in QCD, we identify an invariant light-front coordinate zeta which allows the separation of the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single-variable light-front Schrödinger equation for QCD which determines the eigenspectrum and the light-front wave functions of hadrons for general spin and orbital angular momentum. This light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-J modes on anti-de Sitter (AdS) space.

  19. The Boulder Creek Batholith, Front Range, Colorado

    Science.gov (United States)

    Gable, Dolores J.

    1980-01-01

    The Boulder Creek batholith is the best known of several large Precambrian batholiths of similar rock composition that crop out across central Colorado. The rocks in the batholith belong to the calc-alkaline series and range in composition from granodiorite through quartz diorite (tonalite) to gneissic aplite. Two rock types dominate': the Boulder Creek Granodiorite, the major rock unit, and a more leucocratic and slightly younger unit herein named Twin Spruce Quartz Monzonite. Besides mafic inclusions, which occur mainly in hornblende-bearing phases of the Boulder Creek Granodiorite, there are cogenetic older and younger lenses, dikes, and small plutons of hornblende diorite, hornblendite, gabbro, and pyroxenite. Pyroxenite is not found in the batholith. The Boulder Creek Granodiorite in the batholith represents essentially two contemporaneous magmas, a northern body occurring in the Gold Hill and Boulder quadrangles and a larger southern body exposed in the Blackhawk and the greater parts of the Tungsten and Eldorado Springs quadrangles. The two bodies are chemically and mineralogically distinct. The northern body is richer in CaO and poorer in K2O, is more mafic, and has a larger percentage of plagioclase than the southern body. A crude sequence of rock types occurs from west to east in the batholith accompanied by a change in plagioclase composition from calcic plagioclase on the west to sodic on the east. Ore minerals tend to decrease, and the ratio potassium feldspar:plagioclase increases inward from the western contact of the batholith, indicating that the Boulder Creek batholith is similar to granodiorite batholiths the world over. Emplacement of the Boulder Creek batholith was contemporaneous with plastic deformation and high-grade regional metamorphism that folded the country rock and the batholith contact along west-northwest and north-northwest axes. Also, smaller satellitic granodiorite bodies tend to conform to the trends of foliation and fold axes in

  20. Light-Front Holography: A First Approximation to QCD

    Energy Technology Data Exchange (ETDEWEB)

    de Teramond, Guy F.; Brodsky, Stanley J.

    2008-10-03

    Starting from the Hamiltonian equation of motion in QCD, we identify an invariant light-front coordinate {zeta} which allows the separation of the dynamics of quark and gluon binding from the kinematics of constituent spin and internal orbital angular momentum. The result is a single variable light-front Schroedinger equation for QCD which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. This light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-J modes on anti-de Sitter (AdS) space. This allows us to establish formally a gauge/gravity correspondence between an effective gravity theory defined on AdS5 and light front QCD.

  1. Water chemistry of Rocky Mountain Front Range aquatic ecosystems

    Science.gov (United States)

    Robert C. Musselman; Laura Hudnell; Mark W. Williams; Richard A. Sommerfeld

    1996-01-01

    A study of the water chemistry of Colorado Rocky Mountain Front Range alpine/subalpine lakes and streams in wilderness ecosystems was conducted during the summer of 1995 by the USDA Forest Service Arapaho and Roosevelt National Forests and Rocky Mountain Forest and Range Experiment Station, and the University of Colorado Institute of Alpine and Arctic Research. Data...

  2. Front Range Forest Health Partnership Phase 1 feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Volkin, P

    1998-09-01

    The Front Range Forest Health Partnership is an alliance of individuals, citizen groups, federal, state, private, and nonprofit organizations that formed to promote forest health restoration and reduce fire risks on Colorado's Front Range. The partnership promotes selective thinning to restore forest health and supports economically feasible end uses for wood waste materials. The Phase I study was initiated to determine the environmental and economic feasibility of using wood wastes from forested and urban areas for the production of fuel-grade ethanol.

  3. Quarkonium as a relativistic bound state on the light front

    Science.gov (United States)

    Li, Yang; Maris, Pieter; Vary, James P.

    2017-07-01

    We study charmonium and bottomonium as relativistic bound states in a light-front quantized Hamiltonian formalism. The effective Hamiltonian is based on light-front holography. We use a recently proposed longitudinal confinement to complete the soft-wall holographic potential for the heavy flavors. The spin structure is generated from the one-gluon exchange interaction with a running coupling. The adoption of asymptotic freedom improves the spectroscopy compared with previous light-front results. Within this model, we compute the mass spectroscopy, decay constants and the r.m.s. radii. We also present a detailed study of the obtained light-front wave functions and use the wave functions to compute the light-cone distributions, specifically the distribution amplitudes and parton distribution functions. Overall, our model provides a reasonable description of the heavy quarkonia.

  4. Spin-1 particles with light-front approach

    Directory of Open Access Journals (Sweden)

    de Melo J.P.B.C.

    2014-06-01

    Full Text Available For the vector sector, i.e, mesons with spin-1, the electromagnetic form factors and anothers observables are calculated with the light-front approach. However, the light-front quantum field theory have some problems, for example, the rotational symmetry breaking. We solve that problem added the zero modes contribuition to the matrix elements of the electromagnetic current, besides the valence contribuition. We found that among the four independent matrix elements of the plus component in the light-front helicity basis only the 0 → 0 one carries zero mode contributions.

  5. Vehicle lighting within built-up areas : motor vehicle front lighting on roads with public lighting.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1976-01-01

    One of the questions confronting both the policy makers and scientific researchers concerns the most suitable lighting for vehicles on roads with (fixed) lighting systems. Especially when the lights at the front of the car are involved, this question proves to have many facets. The considerations

  6. Ambient-light-absorbing screen for front projection

    Science.gov (United States)

    Hilborn, E. H.

    1970-01-01

    Screen permits front surface projection of collimated light beam under conditions of high extraneous illumination. Screen has high reflective efficiency over any desired viewing area. Its optical properties are maintained when moisture droplets are present on the external front planar surface. Surface is easily cleaned and maintained.

  7. Nucleon parton distributions in a light-front quark model

    National Research Council Canada - National Science Library

    Gutsche, Thomas; Lyubovitskij, Valery E; Schmidt, Ivan

    2017-01-01

    Continuing our analysis of parton distributions in the nucleon, we extend our light-front quark model in order to obtain both the helicity-independent and the helicity-dependent parton distributions...

  8. Light-Front Holography and AdS/QCD Correspondence

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; de Teramond, Guy F.

    2008-04-23

    Light-Front Holography is a remarkable consequence of the correspondence between string theory in AdS space and conformal field theories in physical-space time. It allows string modes {Phi}(z) in the AdS fifth dimension to be precisely mapped to the light-front wavefunctions of hadrons in terms of a specific light-front impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron. This mapping was originally obtained by matching the exact expression for electromagnetic current matrix elements in AdS space with the corresponding exact expression for the current matrix element using light-front theory in physical space-time. More recently we have shown that one obtains the identical holographic mapping using matrix elements of the energy-momentum tensor, thus providing an important consistency test and verification of holographic mapping from AdS to physical observables defined on the light-front. The resulting light-front Schrodinger equations predicted from AdS/QCD give a good representation of the observed meson and baryon spectra and give excellent phenomenological predictions for amplitudes such as electromagnetic form factors and decay constants.

  9. Light-Front Holography and Non-Perturbative QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; de Teramond, Guy F.; /Costa Rica U.

    2009-12-09

    The combination of Anti-de Sitter space (AdS) methods with light-front holography leads to a semi-classical first approximation to the spectrum and wavefunctions of meson and baryon light-quark bound states. Starting from the bound-state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give the hadronic spectrum, and its eigenmodes represent the probability distribution of the hadronic constituents at a given scale. Applications to the light meson and baryon spectra are presented. The predicted meson spectrum has a string-theory Regge form M{sup 2} = 4{kappa}{sup 2}(n + L + S = 2); i.e., the square of the eigenmass is linear in both L and n, where n counts the number of nodes of the wavefunction in the radial variable {zeta}. The space-like pion form factor is also well reproduced. One thus obtains a remarkable connection between the description of hadronic modes in AdS space and the Hamiltonian formulation of QCD in physical space-time quantized on the light-front at fixed light-front time {tau}. The model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms.

  10. Suggestions for improving vehicle front lighting.

    NARCIS (Netherlands)

    Schreuder, D.A.

    1976-01-01

    Some conclusions: -In lit streets, low-beam headlights contribute little to the visibility of objects, cause glare and can obscure direction indicators. -Presently, it is feasible to adapt the existing vehicle lighting such that it will be characterised by a minimum of about 100 cd in a direction

  11. Quantifying methane emissions and sources in the Colorado Front Range

    Science.gov (United States)

    Hughes, S.; Townsend-Small, A.; Schroeder, J.; Blake, N. J.; Blake, D. R.

    2016-12-01

    Methane is a powerful greenhouse gas and is relatively constant throughout the atmosphere, at 1.8 ppmv. This value, however, is increasing primarily due to anthropogenic sources, including agriculture and natural gas extraction. Here we present atmospheric methane fluxes measured during the Front Range Air Pollution and Photochemistry Experiment (FRAPPE) in July - August 2014 in the Colorado Front Range on the NCAR C-130. During this campaign 775 advanced whole air samples (AWAS) were collected onboard the aircraft and 248 samples were collected on the ground in order to quantify and evaluate air pollution sources. Methane concentrations were measured continuously aboard the aircraft using cavity ringdown spectroscopy. Major sources of methane in this region are oil and natural gas extraction and distribution, landfills, and cattle feed lots. In order to assess the impact of methane emissions on this area, methane flux was evaluated by comparing upwind and downwind concentrations where significant enhancements were observed downwind. We also present information from other hydrocarbons measured in canisters to attribute methane emissions to urban, agricultural, and oil and gas sources. The state of Colorado recently enacted legislation to reduce emissions of hydrocarbons from oil and gas facilities and our measurements will provide a preliminary estimate of whether these regulations are effective.

  12. Wildfire risk transmission in the Colorado Front Range, USA.

    Science.gov (United States)

    Haas, Jessica R; Calkin, David E; Thompson, Matthew P

    2015-02-01

    Wildfires are a global phenomenon that in some circumstances can result in human casualties, economic loss, and ecosystem service degradation. In this article we spatially identify wildfire risk transmission pathways and locate the areas of highest exposure of human populations to wildland fires under severe, but not uncommon, weather events. We quantify varying levels of exposure in terms of population potentially affected and tie the exposure back to the spatial source of the risk for the Front Range of Colorado, USA. We use probabilistic fire simulation modeling to address where fire ignitions are most likely to cause the highest impact to human communities, and to explore the role that various landowners play in that transmission of risk. Our results indicated that, given an ignition and the right fire weather conditions, large areas along the Front Range in Colorado could be exposed to wildfires with high potential to impact human populations, and that overall private ignitions have the potential to impact more people than federal ignitions. These results can be used to identify high-priority areas for wildfire risk mitigation using various mitigation tools. © 2014 Society for Risk Analysis Published 2014. This article is a U.S. government work and is in the public domain for the USA.

  13. Fermions in light front transverse lattice quantum chromodynamics

    Indian Academy of Sciences (India)

    boost invariant wave functions. Furthermore, rotations in the transverse plane remains kinematical. Since vacuum processes receive contributions only from k· =0, Fock vacuum becomes an eigenstate of the light front Hamiltonian in the interacting theory (with the exception of theories with spontaneous symmetry breaking) ...

  14. Covariance of light-front models: pair current

    NARCIS (Netherlands)

    Melo, J.P.B.C. de; Frederico, T.; Naus, H.W.L.; Sauer, P.U.

    1999-01-01

    We compute the + component, i.e., j+ = j0 + j3, of the electromagnetic current of a composite spin-one two-fermion system for vanishing momentum transfer component q+ = q0 + q3. In particular, we extract the nonvanishing pair production amplitude on the light-front. It is a consequence of the

  15. Chiral Boson Theory on the Light-Front

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Prem P.

    1999-09-16

    The framework for describing the quantized theory of chiral boson is discussed. It avoids the conflict with the requirement of the principle of microcausality as is found in the conventional treatment. The discussion of the Floreanini-Jackiw model and its modified version for describing the chiral boson becomes very transparent on the light-front.

  16. Riparian ecosystem consequences of water redistribution along the Colorado Front Range

    Science.gov (United States)

    John D. Wiener; Kathleen A. Dwire; Susan K. Skagen; Robert R. Crifasi; David Yates

    2008-01-01

    Water has shaped the American West. Nowhere is this more evident than along the Front Range of Colorado. At the west end of the famous Great Plains rainfall gradient, the Front Range extends most of the length of Colorado and is one of the fastest growing metropolitan regions in the nation. Annual precipitation along the Front Range averages about 16 inches, and...

  17. Light Cone 2017 : Frontiers in Light Front Hadron Physics : Theory and Experiment.

    CERN Document Server

    2018-01-01

    LC2017 belongs to a series of Light-Cone conferences, which started in 1991. Light Cone conferences are held each year under the auspices of the International Light Cone Advisory Committee (ILCAC) (http://www.ilcacinc.org). The main objective of the Light Cone conference series is to provide a timely update of the progress in light-front theory and its phenomenological applications. Light-front theory provides a suitable framework to calculate observables such as scattering amplitudes, decay rates, spin effects, parton distributions, and other hadronic observables. One of the themes of the conference will be the interface between theory and experiment in hadron physics. The main topics of the program are: o Hadron Physics at present and future colliders o Light Front Field Theory in QED and QCD o AdS/QCD, D Branes and Strings o Hadron Structure : TMDs, GPDs and PDFs o Lattice QCD o QCD at high temperature and density o Higher order QCD corrections

  18. Nucleon parton distributions in a light-front quark model

    Energy Technology Data Exchange (ETDEWEB)

    Gutsche, Thomas [Universitaet Tuebingen, Institut fuer Theoretische Physik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Lyubovitskij, Valery E. [Universitaet Tuebingen, Institut fuer Theoretische Physik, Kepler Center for Astro and Particle Physics, Tuebingen (Germany); Tomsk State University, Department of Physics, Tomsk (Russian Federation); Tomsk Polytechnic University, Laboratory of Particle Physics, Mathematical Physics Department, Tomsk (Russian Federation); Universidad Tecnica Federico Santa Maria, Departamento de Fisica y Centro Cientifico Tecnologico de Valparaiso (CCTVal), Valparaiso (Chile); Schmidt, Ivan [Universidad Tecnica Federico Santa Maria, Departamento de Fisica y Centro Cientifico Tecnologico de Valparaiso (CCTVal), Valparaiso (Chile)

    2017-02-15

    Continuing our analysis of parton distributions in the nucleon, we extend our light-front quark model in order to obtain both the helicity-independent and the helicity-dependent parton distributions, analytically matching the results of global fits at the initial scale μ∝ 1 GeV; they also contain the correct Dokshitzer-Gribov-Lipatov-Altarelli-Parisi evolution. We also calculate the transverse parton, Wigner and Husimi distributions from a unified point of view, using our light-front wave functions and expressing them in terms of the parton distributions q{sub v}(x) and δq{sub v}(x). Our results are very relevant for the current and future program of the COMPASS experiment at SPS (CERN). (orig.)

  19. The 3He spectral function in light-front dynamics

    Directory of Open Access Journals (Sweden)

    Rinaldi Matteo

    2016-01-01

    Full Text Available A distorted spin-dependent spectral function for 3He is considered for the extraction of the transverse-momentum dependent parton distributions in the neutron from semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers, where final state interactions are taken into account. The generalization of the analysis to a Poincaré covariant framework within the light-front dynamics is outlined.

  20. Light-front interpretation of proton generalized polarizabilities.

    Science.gov (United States)

    Gorchtein, M; Lorcé, C; Pasquini, B; Vanderhaeghen, M

    2010-03-19

    We extend the recently developed formalism to extract light-front quark charge densities from nucleon form factor data to the deformations of these quark charge densities when applying an external electric field. We show that the resulting induced polarizations can be extracted from proton generalized polarizabilities. The available data for the generalized electric polarizability of the proton yield a pronounced structure in its induced polarization at large transverse distances, which will be pinned down by forthcoming high precision virtual Compton scattering experiments.

  1. Thermobarometry in a migmatitic terrane, northern Front Range, Colorado

    Energy Technology Data Exchange (ETDEWEB)

    Munn, B.J.; Tracy, R.J. (Virginia Polytechnic Inst. and State Univ., Blacksburg, VA (United States))

    1992-01-01

    Thermobarometric techniques were applied to migmatized rocks from the Cache La Poudre River Canyon. The dominant pelitic assemblage is grt-bt-sil-qz-pl-kfs; stromatic migmatites are abundant. The area was sampled for grt-bearing pelites and amphibolites suitable for grt-bt or grt-hb thermometry and grt-sil-pl-qz or gt-hb-pl-qz barometry. In these texturally complex rocks, garnets exhibit varying degrees of resorption with embayed edges and highly irregular crystal outlines. Garnet compositional maps show complex retrograde zoning with distinct Mn-enriched rims. Analytical points near the rims but inside the retrograde Mn-enriched zone represent compositions as close as possible to those formed at peak conditions, based on the premise that resorption of garnet during retrogression produces rims which are enriched in Mn and Fe. Compositional maps and detailed traverses were used to interpret prograde and retrograde zoning in each garnet to choose points most representative of the peak composition. The authors P-T calculations used these garnet points with matrix bt, hb and pl. Thermobarometeric calculations from outcrops in the eastern part of the canyon yield a peak T of 725 [+-] 50 C and a peak P of 7 [+-] 0.5 kbar. The higher temperature and pressure reported here are consistent with observed phase equilibria and the migmatized nature of the area, and reflect the complicated metamorphic history of the Front Range. Andalusite previously identified in this area is localized in occurrence and retrograde in origin, and is probably related to 1.4 Ga granitic plutonism or to an episode of post-peak deformation; cordierite is typically associated with andalusite in this area (Abbott, 1970). Thus far, neither cordierite nor andalusite has been observed in any of their samples from the Poudre canyon, providing evidence for higher peak P. Therefore, peak metamorphism occurred at about 7 kbar; retrograde metamorphism occurred at lower P during decompression.

  2. Meson Transition Form Factors in Light-Front Holographic QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; Cao, Fu-Guang; /Massey U.; de Teramond, Guy F.; /Costa Rica U.

    2011-06-22

    We study the photon-to-meson transition form factors (TFFs) F{sub M{gamma}}(Q{sup 2}) for {gamma}{gamma}* {yields} M using light-front holographic methods. The Chern-Simons action, which is a natural form in 5-dimensional anti-de Sitter (AdS) space, leads directly to an expression for the photon-to-pion TFF for a class of confining models. Remarkably, the predicted pion TFF is identical to the leading order QCD result where the distribution amplitude has asymptotic form. The Chern-Simons form is local in AdS space and is thus somewhat limited in its predictability. It only retains the q{bar q} component of the pion wavefunction, and further, it projects out only the asymptotic form of the meson distribution amplitude. It is found that in order to describe simultaneously the decay process {pi}{sup 0} {yields} {gamma}{gamma} and the pion TFF at the asymptotic limit, a probability for the q{bar q} component of the pion wavefunction P{sub q{bar q}} = 0.5 is required; thus giving indication that the contributions from higher Fock states in the pion light-front wavefunction need to be included in the analysis. The probability for the Fock state containing four quarks (anti-quarks) which follows from analyzing the hadron matrix elements, P{sub q{bar q}q{bar q}} {approx} 10%, agrees with the analysis of the pion elastic form factor using light-front holography including higher Fock components in the pion wavefunction. The results for the TFFs for the {eta} and {eta}{prime} mesons are also presented. The rapid growth of the pion TFF exhibited by the BABAR data at high Q{sup 2} is not compatible with the models discussed in this article, whereas the theoretical calculations are in agreement with the experimental data for the {eta} and {eta}{prime} TFFs.

  3. Theory and Experiment for Hadrons on the Light-Front

    CERN Document Server

    Salme, Giovanni

    2016-01-01

    LC2015 belongs to a Conference series that started in 1991 under the supervision of the International Light Cone Advisory Committee (ILCAC), with the aim of promoting the research towards a rigorous description of hadrons and nuclei, based on Light-Cone quantization methods. A strong relation with the experimental activity was always pursued and it will be emphasized in the next edition, in order to meet one of the main goals of the whole Light-Cone community "to assist in the development of crucial experimental tests of hadron facilities". The scientific program will feature invited as well as contributed talks, selected in collaboration with the Scientific Advisory Committee and the ILCAC. The main topics to be addressed are: * Hadron physics at present and future facilities; * Nonperturbative methods in quantum field theory * AdS/CFT: theory and applications * Light-front theories in QCD and QED * Relativistic methods for nuclear and hadronic structures * Few-body problems onto the Light cone * Lattice gau...

  4. High Dynamic Range Cognitive Radio Front Ends: Architecture to Evaluation

    Science.gov (United States)

    Ashok, Arun; Subbiah, Iyappan; Varga, Gabor; Schrey, Moritz; Heinen, Stefan

    2016-07-01

    Advent of TV white space digitization has released frequencies from 470 MHz to 790 MHz to be utilized opportunistically. The secondary user can utilize these so called TV spaces in the absence of primary users. The most important challenge for this coexistence is mutual interference. While the strong TV stations can completely saturate the receiver of the cognitive radio (CR), the cognitive radio spurious tones can disturb other primary users and white space devices. The aim of this paper is to address the challenges for enabling cognitive radio applications in WLAN and LTE. In this process, architectural considerations for the design of cognitive radio front ends are discussed. With high-IF converters, faster and flexible implementation of CR enabled WLAN and LTE are shown. The effectiveness of the architecture is shown by evaluating the CR front ends for compliance of standards namely 802.11b/g (WLAN) and 3GPP TS 36.101 (LTE).

  5. AdS/CFT and Light-Front QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; de Teramond, Guy F.

    2008-02-04

    The AdS/CFT correspondence between string theory in AdS space and conformal field theories in physical space-time leads to an analytic, semi-classical model for strongly-coupled QCD which has scale invariance and dimensional counting at short distances and color confinement at large distances. The AdS/CFT correspondence also provides insights into the inherently nonperturbative aspects of QCD such as the orbital and radial spectra of hadrons and the form of hadronic wavefunctions. In particular, we show that there is an exact correspondence between the fifth-dimensional coordinate of AdS space z and a specific impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron in ordinary space-time. This connection leads to AdS/CFT predictions for the analytic form of the frame-independent light-front wavefunctions (LFWFs) of mesons and baryons, the fundamental entities which encode hadron properties. The LFWFs in turn predict decay constants and spin correlations, as well as dynamical quantities such as form factors, structure functions, generalized parton distributions, and exclusive scattering amplitudes. Relativistic light-front equations in ordinary space-time are found which reproduce the results obtained using the fifth-dimensional theory and have remarkable algebraic structures and integrability properties. As specific examples we describe the behavior of the pion form factor in the space and time-like regions and determine the Dirac nucleon form factors in the space-like region. An extension to nonzero quark mass is used to determine hadronic distribution amplitudes of all mesons, heavy and light. We compare our results with the moments of the distribution amplitudes which have recently been computed from lattice gauge theory.

  6. The Colorado Front Range Ecosystem Management Research Project: Accomplishments to date

    Science.gov (United States)

    Brian Kent; Wayne D. Shepperd; Deborah J. Shields

    2000-01-01

    This article briefly describes the goals and objectives for the Colorado Front Range Ecosystem Management Project (FREM). Research under this project has addressed both biophysical and human dimensions problems relating to ecosystem management in the Colorado Front Range. Results of completed work are described, and the status of the ongoing demonstration project at...

  7. Enhanced light output power of quantum cascade lasers from a tilted front facet.

    Science.gov (United States)

    Ahn, Sangil; Schwarzer, Clemens; Zederbauer, Tobias; Detz, Hermann; Andrews, Aaron M; Schrenk, Werner; Strasser, Gottfried

    2013-07-01

    We present a technique for enhancing the light output power of quantum cascade lasers (QCLs) by tilting of the front facet, which leads to a change of the modal reflectivity, resulting in an asymmetric light intensity distribution along the laser cavity. This asymmetry provides most of the light being emitted through one facet of the laser. An experimental study of threshold current, slope efficiency and light output power as a function of the front facet angles were performed and compared to conventional QCLs. The lasers with a front facet angle of 8° shows a 20% improved power output from the front facet.

  8. Light-Front Holography and Gauge/Gravity Duality: The Light Meson and Baryon Spectra

    Energy Technology Data Exchange (ETDEWEB)

    de Teramond, Guy F.; /Costa Rica U.; Brodsky, Stanley J.; /SLAC

    2009-12-09

    Starting from the bound state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give the hadronic spectrum, and its eigenmodes represent the probability amplitudes of the hadronic constituents at a given scale. An effective classical gravity description in a positive-sign dilaton background exp(+{kappa}{sup 2}z{sup 2}) is given for the phenomenologically successful soft-wall model which naturally encodes the internal structure of hadrons and their orbital angular momentum. Applications to the light meson and baryon spectrum are presented.

  9. Facts up front versus traffic light food labels: a randomized controlled trial.

    Science.gov (United States)

    Roberto, Christina A; Bragg, Marie A; Schwartz, Marlene B; Seamans, Marissa J; Musicus, Aviva; Novak, Nicole; Brownell, Kelly D

    2012-08-01

    The U.S. food and beverage industry recently released a new front-of-package nutrition labeling system called Facts Up Front that will be used on thousands of food products. To test consumer understanding of the Facts Up Front system (Facts Up Front) compared to the Multiple Traffic Light system (Traffic Light). Facts Up Front displays grams/milligrams and percentage daily value information for various nutrients; Traffic Light uses an interpretive color-coded scheme to alert consumers to low, medium, and high levels of certain nutrients. Participants in an Internet-based study were randomized to one of five front-of-package label conditions: (1) no label; (2) Traffic Light; (3) Traffic Light plus information about protein and fiber (Traffic Light+); (4) Facts Up Front; or (5) Facts Up Front plus information about "nutrients to encourage" (Facts Up Front+). A total of 703 adults recruited through an online database in May 2011 participated in this study, and data were analyzed in June 2011. Total percentage correct quiz scores were generated reflecting participants' ability to compare two foods on nutrient levels, based on their labels, and to estimate amounts of saturated fat, sugar, sodium, fiber and protein in the foods. The front-of-package label groups outperformed the control group on nearly all of the nutrient quizzes (pFacts Up Front group on the saturated fat quiz, or from the Facts Up Front+ group on the sugars quiz. Those in the Traffic Light+ group had the best overall performance (>80% on all quizzes). Overall, those in the Traffic Light+ condition performed better than those in the Facts Up Front conditions on measures of nutrition knowledge and label perceptions. This study is registered at clinicaltrials.gov NCT01626729. Copyright © 2012 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.

  10. Double parton correlations in Light-Front constituent quark models

    Directory of Open Access Journals (Sweden)

    Rinaldi Matteo

    2015-01-01

    Full Text Available Double parton distribution functions (dPDF represent a tool to explore the 3D proton structure. They can be measured in high energy proton-proton and proton nucleus collisions and encode information on how partons inside a proton are correlated among each other. dPFDs are studied here in the valence quark region, by means of a constituent quark model, where two particle correlations are present without any additional prescription. This framework allows to understand the dynamical origin of the correlations and to clarify which, among the features of the results, are model independent. Use will be made of a relativistic light-front scheme, able to overcome some drawbacks of the previous calculation. Transverse momentum correlations, due to the exact treatment of the boosts, are predicted and analyzed. The role of spin correlations is also shown. Due to the covariance of the approach, some symmetries of the dPDFs are seen unambigously. For the valence sector, also the study of the QCD evolution of the model results, which can be performed safely thanks to the property of good support, has been also completed.

  11. Digital geospatial datasets in support of hydrologic investigations of the Colorado Front Range Infrastructure Resources Project

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The U.S. Geological Survey developed this dataset as part of the Colorado Front Range Infrastructure Resources Project (FRIRP). One goal of the FRIRP was to provide...

  12. Potential Areas of Future Oil and Gas Development, Greater Wattenberg Area, Front Range of Colorado (friogdevu)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The potential for oil and gas development in the greater Wattenberg area (GWA), which lies near the Front Range between Denver and Greeley, Colo., in the Denver...

  13. Photosensitivity control of an isotropic medium through polarization of light pulses with tilted intensity front.

    Science.gov (United States)

    Kazansky, Peter G; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Beresna, Martynas; Gecevičius, Mindaugas; Svirko, Yuri; Akturk, Selcuk; Qiu, Jianrong; Miura, Kiyotaka; Hirao, Kazuyuki

    2011-10-10

    We present the first experimental evidence of anisotropic photosensitivity of an isotropic homogeneous medium under uniform illumination. Our experiments reveal fundamentally new type of light induced anisotropy originated from the hidden asymmetry of pulsed light beam with a finite tilt of intensity front. We anticipate that the observed phenomenon, which enables employing mutual orientation of a light polarization plane and pulse front tilt to control interaction of matter with ultrashort light pulses, will open new opportunities in material processing.

  14. Electromagnetic form factors for spin-1 particles with the light-front

    Energy Technology Data Exchange (ETDEWEB)

    Mello, Clayton S. [Laboratório de Física Teórica e Computacional (LFTC), Universidade Cruzeiro do Sul, 01506-000, São Paulo (Brazil); Departamento de Física, Instituto Tecnológico de Aeronáutica, 12.228-900 São José dos Campos, São Paulo (Brazil); Nunes da Silva, Anacé; Melo, J.P.B.C. de [Laboratório de Física Teórica e Computacional (LFTC), Universidade Cruzeiro do Sul, 01506-000, São Paulo (Brazil); Frederico, T. [Departamento de Física, Instituto Tecnológico de Aeronáutica, 12.228-900 São José dos Campos, São Paulo (Brazil)

    2014-06-15

    This work is dedicate to investigate the spin-1 electromagnetic form factors with the light-front quantum field theory approach. All prescriptions with the light-front approach are contamined by the zero-modes contribuitions to the electromagnetic matrix elements of the electromagnetic current with the plus component of the current; however, the Inna Grach prescriptions it is immune for the zero modes contribuitions. We show numerically the contribution of zero-modes for the electromagnetic current in the case of the vector particles in the light-front quantum field theory. Also the electromagnetic observables, like electromagnetic form factors, radius and the decay constant are presented.

  15. Long Valley caldera and the UCERF depiction of Sierra Nevada range-front faults

    Science.gov (United States)

    Hill, David P.; Montgomery-Brown, Emily K.

    2015-01-01

    Long Valley caldera lies within a left-stepping offset in the north-northwest-striking Sierra Nevada range-front normal faults with the Hilton Creek fault to the south and Hartley Springs fault to the north. Both Uniform California Earthquake Rupture Forecast (UCERF) 2 and its update, UCERF3, depict slip on these major range-front normal faults as extending well into the caldera, with significant normal slip on overlapping, subparallel segments separated by ∼10  km. This depiction is countered by (1) geologic evidence that normal faulting within the caldera consists of a series of graben structures associated with postcaldera magmatism (intrusion and tumescence) and not systematic down-to-the-east displacements consistent with distributed range-front faulting and (2) the lack of kinematic evidence for an evolving, postcaldera relay ramp structure between overlapping strands of the two range-front normal faults. The modifications to the UCERF depiction described here reduce the predicted shaking intensity within the caldera, and they are in accord with the tectonic influence that underlapped offset range-front faults have on seismicity patterns within the caldera associated with ongoing volcanic unrest.

  16. High Dynamic Range RF Front End with Noise Cancellation and Linearization for WiMAX Receivers

    Directory of Open Access Journals (Sweden)

    J.-M. Wu

    2012-06-01

    Full Text Available This research deals with verification of the high dynamic range for a heterodyne radio frequency (RF front end. A 2.6 GHz RF front end is designed and implemented in a hybrid microwave integrated circuit (HMIC for worldwide interoperability for microwave access (WiMAX receivers. The heterodyne RF front end consists of a low-noise amplifier (LNA with noise cancellation, an RF bandpass filter (BPF, a downconverter with linearization, and an intermediate frequency (IF BPF. A noise canceling technique used in the low-noise amplifier eliminates a thermal noise and then reduces the noise figure (NF of the RF front end by 0.9 dB. Use of a downconverter with diode linearizer also compensates for gain compression, which increases the input-referred third-order intercept point (IIP3 of the RF front end by 4.3 dB. The proposed method substantially increases the spurious-free dynamic range (DRf of the RF front end by 3.5 dB.

  17. Disturbance impacts on understory plant communities of the Colorado Front Range

    Science.gov (United States)

    Paula J. Fornwalt

    2009-01-01

    Pinus ponderosa - Pseudotsuga menziesii (ponderosa pine - Douglas-fir) forests of the Colorado Front Range have experienced a range of disturbances since they were settled by European-Americans approximately 150 years ago, including settlement-era logging and domestic grazing, and more recently, wildfire. In this dissertation, I...

  18. Light-Front Quantization Approach to the Gauge Gravity Correspondence and Hadron Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    de Teramond, Guy F.; /Costa Rica U.; Brodsky, Stanley J.; /SLAC

    2010-05-26

    We find a correspondence between semiclassical QCD quantized on the light-front and a dual gravity model in anti-de Sitter (AdS) space, thus providing an initial approximation to QCD in its strongly coupled regime. This correspondence - light-front holography - leads to a light-front Hamiltonian and relativistic bound-state wave equations that are functions of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within hadrons at equal lightfront time. The eigenvalues of the resulting light-front Schrodinger and Dirac equations are consistent with the observed light meson and baryon spectrum, and the eigenmodes provide the light-front wavefunctions, the probability amplitudes describing the dynamics of the hadronic constituents. The light-front equations of motion, which are dual to an effective classical gravity theory, possess remarkable algebraic and integrability properties which are dictated by the underlying conformal properties of the theory. We extend the algebraic construction to include a confining potential while preserving the integrability of the mesonic and baryonic bound-state equations.

  19. Applications of AdS/QCD and Light-Front Holography to Baryon Physics

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; de Teramond, Guy F.; /Costa Rica U.

    2011-08-22

    The correspondence between theories in anti-de Sitter space and field theories in physical space-time leads to an analytic, semiclassical model for strongly-coupled QCD which has scale invariance at short distances and color confinement at large distances. These equations, for both mesons and baryons, give a very good representation of the observed hadronic spectrum, including a zero mass pion. Light-front holography allows hadronic amplitudes in the AdS fifth dimension to be mapped to frame-independent light-front wavefunctions of hadrons in physical space-time, thus providing a relativistic description of hadrons at the amplitude level. The meson and baryon wavefunctions derived from light-front holography and AdS/QCD also have remarkable phenomenological features, including predictions for the electromagnetic form factors and decay constants. The approach can be systematically improved using light-front Hamiltonian methods. Some novel features of QCD for baryon physics are also discussed.

  20. Optimal front light design for reflective displays under different ambient illumination

    Science.gov (United States)

    Wang, Sheng-Po; Chang, Ting-Ting; Li, Chien-Ju; Bai, Yi-Ho; Hu, Kuo-Jui

    2011-01-01

    The goal of this study is to find out the optimal luminance and color temperature of front light for reflective displays in different ambient illumination by conducting series of psychophysical experiments. A color and brightness tunable front light device with ten LED units was built and been calibrated to present 256 luminance levels and 13 different color temperature at fixed luminance of 200 cd/m2. The experiment results revealed the best luminance and color temperature settings for human observers under different ambient illuminant, which could also assist the e-paper manufacturers to design front light device, and present the best image quality on reflective displays. Furthermore, a similar experiment procedure was conducted by utilizing new flexible e-signage display developed by ITRI and an optimal front light device for the new display panel has been designed and utilized.

  1. Free Space Ranging Utilizing Chaotic Light

    Directory of Open Access Journals (Sweden)

    Tong Zhao

    2013-01-01

    Full Text Available We report our recent works on free space ranging with chaotic light. Using a laser diode with optical feedback as chaotic source, a prototype of chaotic lidar has been developed and it can achieve a range-independent resolution of 18 cm and measurable distance of 130 m at least. And its antijamming performance is presented experimentally and numerically. Finally, we, respectively, employ the wavelet denoising method and the correlation average discrete-component elimination algorithm to detect the chaotic signal in noisy environment and suppress the side-lobe noise of the correlation trace.

  2. Forest biomass and tree planting for fossil fuel offsets in the Colorado Front Range

    Science.gov (United States)

    Mike A. Battaglia; Kellen Nelson; Dan Kashian; Michael G. Ryan

    2010-01-01

    This study estimates the amount of carbon available for removal in fuel reduction and reforestation treatments in montane forests of the Colorado Front Range based on site productivity, pre-treatment basal area, and planting density. Thinning dense stands will yield the greatest offsets for biomass fuel. However, this will also yield the greatest carbon losses, if the...

  3. AdS/QCD and Applications of Light-Front Holography

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC /Southern Denmark U., CP3-Origins; Cao, Fu-Guang; /Massey U.; de Teramond, Guy F.; /Costa Rica U.

    2012-02-16

    Light-Front Holography leads to a rigorous connection between hadronic amplitudes in a higher dimensional anti-de Sitter (AdS) space and frame-independent light-front wavefunctions of hadrons in 3 + 1 physical space-time, thus providing a compelling physical interpretation of the AdS/CFT correspondence principle and AdS/QCD, a useful framework which describes the correspondence between theories in a modified AdS5 background and confining field theories in physical space-time. To a first semiclassical approximation, where quantum loops and quark masses are not included, this approach leads to a single-variable light-front Schroedinger equation which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. The coordinate z in AdS space is uniquely identified with a Lorentz-invariant coordinate {zeta} which measures the separation of the constituents within a hadron at equal light-front time. The internal structure of hadrons is explicitly introduced and the angular momentum of the constituents plays a key role. We give an overview of the light-front holographic approach to strongly coupled QCD. In particular, we study the photon-to-meson transition form factors (TFFs) F{sub M{gamma}}(Q{sup 2}) for {gamma}{gamma}* {yields} M using light-front holographic methods. The results for the TFFs for the {eta} and {eta}' mesons are also presented. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method for computing the hadronization of quark and gluon jets at the amplitude level is outlined.

  4. Ensemble-based analysis of Front Range severe convection on 6-7 June 2012: Forecast uncertainty and communication of weather information to Front Range decision-makers

    Science.gov (United States)

    Vincente, Vanessa

    The variation of topography in Colorado not only adds to the beauty of its landscape, but also tests our ability to predict warm season severe convection. Deficient radar coverage and limited observations make quantitative precipitation forecasting quite a challenge. Past studies have suggested that greater forecast skill of mesoscale convection initiation and precipitation characteristics are achievable considering an ensemble with explicitly predicted convection compared to one that has parameterized convection. The range of uncertainty and probabilities in these forecasts can help forecasters in their precipitation predictions and communication of weather information to emergency managers (EMs). EMs serve an integral role in informing and protecting communities in anticipation of hazardous weather. An example of such an event occurred on the evening of 6 June 2012, where areas to the lee of the Rocky Mountain Front Range were impacted by flash-flood-producing severe convection that included heavy rain and copious amounts of hail. Despite the discrepancy in the timing, location and evolution of convection, the convection-allowing ensemble forecasts generally outperformed those of the convection-parameterized ensemble in representing the mesoscale processes responsible for the 6-7 June severe convective event. Key features sufficiently reproduced by several of the convection-allowing ensemble members resembled the observations: 1) general location of a convergence boundary east of Denver, 2) convective initiation along the boundary, 3) general location of a weak cold front near the Wyoming/Nebraska border, and 4) cold pools and moist upslope characteristics that contributed to the backbuilding of convection. Members from the convection-parameterized ensemble that failed to reproduce these results displaced the convergence boundary, produced a cold front that moved southeast too quickly, and used the cold front for convective initiation. The convection

  5. Douglas-fir tussock moth- and Douglas-fir beetle-caused mortality in a ponderosa pine/Douglas-fir forest in the Colorado Front Range, USA

    Science.gov (United States)

    Jose F. Negron; Ann M. Lynch; Willis C. Schaupp; Vladimir Bocharnikov

    2014-01-01

    An outbreak of the Douglas-fir tussock moth, Orgyia pseudotsugata McDunnough, occurred in the South Platte River drainage on the Pike-San Isabel National Forest in the Colorado Front Range attacking Douglas-fir, Pseudotsuga menziesii (Mirb.) Franco. Stocking levels, species composition, and tree size in heavily and lightly defoliated stands were similar. Douglas-fir...

  6. AdS/QCD and Light Front Holography: A New Approximation to QCD

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; de Teramond, Guy

    2010-02-15

    The combination of Anti-de Sitter space (AdS) methods with light-front holography leads to a semi-classical first approximation to the spectrum and wavefunctions of meson and baryon light-quark bound states. Starting from the bound-state Hamiltonian equation of motion in QCD, we derive relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. Its eigenvalues give the hadronic spectrum, and its eigenmodes represent the probability distribution of the hadronic constituents at a given scale. Applications to the light meson and baryon spectra are presented. The predicted meson spectrum has a string-theory Regge form M{sup 2} = 4{kappa}{sup 2}(n+L+S/2); i.e., the square of the eigenmass is linear in both L and n, where n counts the number of nodes of the wavefunction in the radial variable {zeta}. The space-like pion form factor is also well reproduced. One thus obtains a remarkable connection between the description of hadronic modes in AdS space and the Hamiltonian formulation of QCD in physical space-time quantized on the light-front at fixed light-front time {tau}. The model can be systematically improved by using its complete orthonormal solutions to diagonalize the full QCD light-front Hamiltonian or by applying the Lippmann-Schwinger method in order to systematically include the QCD interaction terms.

  7. Angular momentum conservation law in light-front quantum field theory

    Energy Technology Data Exchange (ETDEWEB)

    Chiu, Kelly Yu-Ju; Brodsky, Stanley J.; /SLAC /Stanford U.

    2017-03-01

    We prove the Lorentz invariance of the angular momentum conservation law and the helicity sum rule for relativistic composite systems in the light-front formulation. We explicitly show that j 3 , the z -component of the angular momentum remains unchanged under Lorentz transformations generated by the light-front kinematical boost operators. The invariance of j 3 under Lorentz transformations is a feature unique to the front form. Applying the Lorentz invariance of the angular quantum number in the front form, we obtain a selection rule for the orbital angular momentum which can be used to eliminate certain interaction vertices in QED and QCD. We also generalize the selection rule to any renormalizable theory and show that there exists an upper bound on the change of orbital angular momentum in scattering processes at any fixed order in perturbation theory.

  8. Charmonium spectrum and diffractive production in a light-front Hamiltonian approach

    Science.gov (United States)

    Chen, Guangyao; Li, Yang; Maris, Pieter; Tuchin, Kirill; Vary, James P.

    2017-08-01

    We study exclusive charmonium production in diffractive deep inelastic scattering and ultra-peripheral heavy-ion collisions within the dipole picture. The mass spectrum and light-front wavefunctions of charmonium are obtained from the basis light-front quantization approach, using the one-gluon exchange interaction plus a confining potential inspired by light-front holography. We apply these light-front wavefunctions to exclusive charmonium production. The resulting cross sections are in reasonable agreement with electron-proton collision data at HERA and ultra-peripheral nucleus collision measurements at RHIC and LHC. The charmonium cross-section has model dependence on the dipole model. We observe that the cross-section ratio of excited states to the ground state has a weaker dependence than the cross-section itself. We suggest that measurements of excited states of heavy quarkonium production in future electron-ion collision experiments will impose rigorous constraints on heavy quarkonium light-front wave-functions, thus improving our understanding of meson structure, which eventually will help us develop a precise description of the gluon distribution function in the small-x regime.

  9. Light-front projection of spin-1 electromagnetic current and zero-modes

    Energy Technology Data Exchange (ETDEWEB)

    Melo, J.P.B.C. de [Laboratorio de Fisica Teorica e Computacao Cientifica - LFTC, Universidade Cruzeiro do Sul, 01506-000 Sao Paulo, SP (Brazil); Frederico, T., E-mail: tobias@ita.br [Instituto Tecnologico de Aeronautica, DCTA, 12.228-900 Sao Jose dos Campos, SP (Brazil)

    2012-02-14

    The issue of the contribution of zero-modes to the light-front projection of the electromagnetic current of phenomenological models of vector particles vertices is addressed in the Drell-Yan frame. Our analytical model of the Bethe-Salpeter amplitude of a spin-1 fermion-antifermion composite state gives a physically motivated light-front wave function symmetric by the exchange of the fermion and antifermion, as in the {rho}-meson case. We found that among the four independent matrix elements of the plus component in the light-front helicity basis only the 0{yields}0 one carries zero-mode contributions. Our derivation generalizes to symmetric models, important for applications, the above conclusion found for a simplified non-symmetrical form of the spin-1 Bethe-Salpeter amplitude with photon-fermion point-like coupling and also for a smeared fermion-photon vertex model.

  10. Principles and practices for the restoration of ponderosa pine and dry mixed-conifer forests of the Colorado Front Range

    Science.gov (United States)

    Robert N. Addington; Gregory H. Aplet; Mike A. Battaglia; Jennifer S. Briggs; Peter M. Brown; Antony S. Cheng; Yvette Dickinson; Jonas A. Feinstein; Kristen A. Pelz; Claudia M. Regan; Jim Thinnes; Rick Truex; Paula J. Fornwalt; Benjamin Gannon; Chad W. Julian; Jeffrey L. Underhill; Brett Wolk

    2018-01-01

    Wildfires have become larger and more severe over the past several decades on Colorado’s Front Range, catalyzing greater investments in forest management intended to mitigate wildfire risks. The complex ecological, social, and political context of the Front Range, however, makes forest management challenging, especially where multiple management goals including forest...

  11. Light-Front Quantization and AdS/QCD: An Overview

    Energy Technology Data Exchange (ETDEWEB)

    de Teramond, Guy F.; /Costa Rica U.; Brodsky, Stanley J.; /SLAC /Stanford U., Phys. Dept.

    2011-08-19

    We give an overview of the light-front holographic approach to strongly coupled QCD, whereby a confining gauge theory, quantized on the light front, is mapped to a higher-dimensional anti de Sitter (AdS) space. The framework is guided by the AdS/CFT correspondence incorporating a gravitational background asymptotic to AdS space which encodes the salient properties of QCD, such as the ultraviolet conformal limit at the AdS boundary at z {yields} 0, as well as modifications of the geometry in the large z infrared region to describe confinement and linear Regge behavior. There are two equivalent procedures for deriving the AdS/QCD equations of motion: one can start from the Hamiltonian equation of motion in physical space time by studying the off-shell dynamics of the bound state wavefunctions as a function of the invariant mass of the constituents. To a first semiclassical approximation, where quantum loops and quark masses are not included, this leads to a light-front Hamiltonian equation which describes the bound state dynamics of light hadrons in terms of an invariant impact variable {zeta} which measures the separation of the partons within the hadron at equal light-front time. Alternatively, one can start from the gravity side by studying the propagation of hadronic modes in a fixed effective gravitational background. Both approaches are equivalent in the semiclassical approximation. This allows us to identify the holographic variable z in AdS space with the impact variable {zeta}. Light-front holography thus allows a precise mapping of transition amplitudes from AdS to physical space-time. The internal structure of hadrons is explicitly introduced and the angular momentum of the constituents plays a key role.

  12. AdS/QCD, Light-Front Holography, and Sublimated Gluons

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; de Teramond, Guy F.; /Costa Rica U.

    2012-02-16

    The gauge/gravity duality leads to a simple analytical and phenomenologically compelling nonperturbative approximation to the full light-front QCD Hamiltonian - 'Light-Front Holography', which provides a Lorentz-invariant first-approximation to QCD, and successfully describes the spectroscopy of light-quark meson and baryons, their elastic and transition form factors, and other hadronic properties. The bound-state Schroedinger and Dirac equations of the soft-wall AdS/QCD model predict linear Regge trajectories which have the same slope in orbital angular momentum L and radial quantum number n for both mesons and baryons. Light-front holography connects the fifth-dimensional coordinate of AdS space z to an invariant impact separation variable {zeta} in 3+1 space at fixed light-front time. A key feature is the determination of the frame-independent light-front wavefunctions of hadrons - the relativistic analogs of the Schroedinger wavefunctions of atomic physics which allow one to compute form factors, transversity distributions, spin properties of the valence quarks, jet hadronization, and other hadronic observables. One thus obtains a one-parameter color-confining model for hadron physics at the amplitude level. AdS/QCD also predicts the form of the non-perturbative effective coupling {alpha}{sub s}{sup AdS} (Q) and its {beta}-function with an infrared fixed point which agrees with the effective coupling a{sub g1} (Q{sup 2}) extracted from measurements of the Bjorken sum rule below Q{sup 2} < 1 GeV{sup 2}. This is consistent with a flux-tube interpretation of QCD where soft gluons with virtualities Q{sup 2} < 1 GeV{sup 2} are sublimated into a color-confining potential for quarks. We discuss a number of phenomenological hadronic properties which support this picture.

  13. Nucleon-generalized parton distributions in the light-front quark model

    Indian Academy of Sciences (India)

    2016-01-12

    Jan 12, 2016 ... We calculate the generalized parton distributions (GPDs) for the up- and downquarks in nucleon using the effective light-front wavefunction. The results obtained for GPDs in momentum and impact parameter space are comparable with phenomenological parametrization methods.

  14. Factors controlling streambed coverage of Didymosphenia geminata in two regulated streams in the Colorado Front Range

    OpenAIRE

    Miller, Matthew P; McKnight, Diane M.; Cullis, James D.; Greene, Alicia; Vietti, Kristin; Liptzin, Daniel

    2009-01-01

    Didymosphenia geminata is a stalk-forming freshwater diatom which was historically found primarily in oligotrophic lakes and streams, but has recently become a nuisance species in many lotic systems worldwide. In the last 5–8 years, D. geminata has become established in Boulder Creek and South Boulder Creek, two regulated montane streams in the Front Range of the Colorado Rocky Mountains. Factors that may influence the growth of D. geminata were monitored during the summer of 2006. D. geminat...

  15. New insights into debris-flow hazards from an extraordinary event in the Colorado Front Range

    Science.gov (United States)

    Coe, Jeffrey A.; Kean, Jason W.; Godt, Jonathan W.; Baum, Rex L.; Jones, Eric S.; Gochis, David; Anderson, Gregory S

    2016-01-01

    Rainfall on 9–13 September 2013 triggered at least 1,138 debris flows in a 3430 km2 area of the Colorado Front Range. The historical record reveals that the occurrence of these flows over such a large area in the interior of North America is highly unusual. Rainfall that triggered the debris flows began after ~75 mm of antecedent rain had fallen, a relatively low amount compared to other parts of the United States. Most flows were triggered in response to two intense rainfall periods, one 12.5-hour-long period on 11–12 September, and one 8-hour-long period on 12 September. The maximum 10 min. intensities during these periods were 67 and 39 mm/hr. Ninety-five percent of flows initiated in canyons and on hogbacks at elevations lower than a widespread erosion surface of low slope and relief (25°), predominantly south- and east-facing slopes with upslope contributing areas 3300 m2. Areal concentrations of debris flows revealed that colluvial soils formed on sedimentary rocks were more susceptible to flows than soils on crystalline rocks. This event should serve as an alert to government authorities, emergency responders, and residents in the Front Range and other interior continental areas with steep slopes. Widespread debris flows in these areas occur infrequently but may pose a greater risk than in areas with shorter return periods, because the public is typically unprepared for them.

  16. Bayesian analysis of light-front models and the nucleon's charmed sigma term

    Science.gov (United States)

    Hobbs, T. J.; Alberg, Mary; Miller, Gerald A.

    2017-10-01

    We present the results of a recent analysis to study the nucleon's charm sigma term, σc c ¯. We construct a minimal model in terms of light-front variables and constrain the range of possibilities using extant knowledge from deeply inelastic scattering (DIS) and Bayesian parameter estimation, ultimately computing σc c ¯ in an explicitly covariant manner. We find a close correlation between a possible nonperturbative component of the charm structure function, F2,IC c c ¯ , and σc c ¯. Independent of the prescription for the covariant relativistic quark-nucleon vertex, we determine σc c ¯ under several different scenarios for the magnitude of intrinsic charm in DIS, namely ⟨x ⟩c+c ¯=0.1 %, 0.35%, and 1%, obtaining for these σc c ¯=4 ±4 , 12 ±13 , and 32 ±34 MeV , respectively. These results imply the existence of a reciprocity between the intrinsic charm parton distribution function and σc c ¯ such that new information from either DIS or improved determinations of σc c ¯ could significantly impact constraints to the charm sector of the proton wave function.

  17. The Potential for Long-Term Impacts of Extreme Events in the Front Range of Colorado

    Science.gov (United States)

    Losleben, M. V.; Caine, N.; Flanagan, C.; McKnight, D.; Monson, R.

    2005-12-01

    Extreme climatic events can trigger a cascade of events, or cause a step function change, in environmental systems that changes the balance of one or more environmental systems, such as bio-, geo-, hydro-, or chemical. They occur at all spatial, temporal, and intensity scales, some easily measurable, others more difficult. Moreover, not all extreme events have lasting environmental impacts. Whether they foreset the environmental clock or not is dependent on the particular system sensitivity in the geographic area of interest, as well as the type of event. Obviously, sufficient environmental data are necessary to detect and evaluate the potential of an extreme event to cause long-term change, and data scarcity is often a problem in the mountains of the western US. We look at the available data for five extreme events affecting the Front Range of the Colorado Rocky Mountains, and find a range of effects, suggesting that Front Range systems are more sensitive to drought than excessive moisture, and to events of longer duration. The events are defined by the surface climatic parameters of snow, rain, or temperature, and characterized by their synoptic atmospheric circulation pattern. Factors assessing the environmental impact include net ecosystem carbon dioxide exchange, alpine lake algal populations and hydrologic residence times, rock glacier temperatures, snowpack, and reservoir storage. The events are the April 15-16, 1921 record U.S. 24-hour snowfall at Silver Lake, CO, the 1981-86 upper elevation cold period in central Colorado and southern Wyoming, an anomalously high April and May 1995 snowfall, the 2002 drought, and the March 17-19, 2003 anomalously high snowfall in the South Platte and Arkansas River basins of Colorado.

  18. Light-Front Hamiltonian Approach to the Bound-State Problem in Quantum Electrodynamics

    Science.gov (United States)

    Jones, Billy D.

    1997-10-01

    Why is the study of the Lamb shift in hydrogen, which at the level of detail found in this paper was largely completed by Bethe in 1947, of any real interest today? While completing such a calculation using new techniques may be very interesting for formal and academic reasons, our primary motivation is to lay groundwork for precision bound-state calculations in QCD. The Lamb shift provides an excellent pedagogical tool for illustrating light-front Hamiltonian techniques, which are not widely known; but more importantly it presents three of the central dynamical and computational problems that we must face to make these techniques useful for solving QCD: How does a constituent picture emerge in a gauge field theory? How do bound-state energy scales emerge non-perturbatively? How does rotational symmetry emerge in a non-perturbative light-front calculation?

  19. Spectrum and structure of Bc mesons on the light-front

    Science.gov (United States)

    Tang, Shuo; Li, Yang; Maris, Pieter; Vary, James

    2017-09-01

    Recent measurements at LHC have renewed the theoretical interest in the production, spectrum and decay of charm-beauty (Bc) mesons. We solve for the low-lying (b c) states using a light-front Hamiltonian with a confining interaction based on AdS/QCD holography plus one-gluon exchange that gives a good description of charmonium and botomonium. Without adjusting any parameters we find good agreement for the ground state Bc mass compared to experiment. We also discuss the spectrum below threshold, and compare our results with quark model calculations. The corresponding light-front wave functions can be used to calculate other observables such as the decays constants, distribution amplitudes, and GPDs. DOE-FG02-87ER40371.

  20. In-medium pion valence distributions in a light-front model

    Energy Technology Data Exchange (ETDEWEB)

    Melo, J.P.B.C. de, E-mail: joao.mello@cruzeirodosul.edu.br [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Tsushima, K. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); Ahmed, I. [Laboratório de Física Teórica e Computacional – LFTC, Universidade Cruzeiro do Sul, 01506-000 São Paulo (Brazil); National Center for Physics, Quaidi-i-Azam University Campus, Islamabad 45320 (Pakistan)

    2017-03-10

    Pion valence distributions in nuclear medium and vacuum are studied in a light-front constituent quark model. The in-medium input for studying the pion properties is calculated by the quark-meson coupling model. We find that the in-medium pion valence distribution, as well as the in-medium pion valence wave function, are substantially modified at normal nuclear matter density, due to the reduction in the pion decay constant.

  1. Pesudoscalar transition form factors within the light-front quark model

    Science.gov (United States)

    Geng, Chao-Qiang; Lih, Chong-Chung

    2012-09-01

    We study the transition form factors of the pesudoscalar mesons (π,η, and η') as functions of the momentum transfer Q2 within the light-front quark model. We compare our results with the recent experimental data by CELLO, CLEO, BaBar and Belle collaborations. By considering the possible uncertainties from the quark masses, we illustrate that our predicted form factors can fit with all the data, including those at the large Q2 regions.

  2. Pauli-Villars regularization in nonperturbative Hamiltonian approach on the light front

    Energy Technology Data Exchange (ETDEWEB)

    Malyshev, M. Yu., E-mail: mimalysh@yandex.ru; Paston, S. A.; Prokhvatilov, E. V.; Zubov, R. A.; Franke, V. A. [Saint Petersburg State University, Saint Petersburg (Russian Federation)

    2016-01-22

    The advantage of Pauli-Villars regularization in quantum field theory quantized on the light front is explained. Simple examples of scalar λφ{sup 4} field theory and Yukawa-type model are used. We give also an example of nonperturbative calculation in the theory with Pauli-Villars fields, using for that a model of anharmonic oscillator modified by inclusion of ghost variables playing the role similar to Pauli-Villars fields.

  3. AdS/QCD and Applications of Light-Front Holography

    DEFF Research Database (Denmark)

    Brodsky, S. J.; Cao, F. G.; de Teramond, G. F.

    2012-01-01

    -to-meson transition form factors (TFFs) F-M gamma (Q(2)) for gamma* -> M using light-front holographic methods. The results for the TFFs for the eta and eta' mesons are also presented. Some novel features of QCD are discussed, including the consequences of confinement for quark and gluon condensates. A method...... for computing the hadronization of quark and gluon jets at the amplitude level is outlined....

  4. Electromagnetic structure and weak decay of meson K in a light-front QCD-inspired

    CERN Document Server

    Pereira, Fabiano P; Frederico, T; Tomio, Lauro

    2007-01-01

    The kaon electromagnetic (e.m.) form factor is reviewed considering a light-front constituent quark model. In this approach, it is discussed the relevance of the quark-antiquark pair terms for the full covariance of the e.m. current. It is also verified, by considering a QCD dynamical model, that a good agreement with experimental data can be obtained for the kaon weak decay constant once a probability of about 80% of the valence component is taken into account.

  5. A low-power high dynamic range front-end ASIC for imaging calorimeters

    CERN Document Server

    Bagliesi, M G; Marrocchesi, P S; Meucci, M; Millucci, V; Morsani, F; Paoletti, R; Pilo, F; Scribano, A; Turini, N; Valle, G D

    2002-01-01

    High granularity calorimeters with shower imaging capabilities require dedicated front-end electronics. The ICON 4CH and VA4 PMT chip-set is suitable for very high dynamic range systems with strict noise requirements. The ICON 4CH is a 4 channel input, 12 channel output ASIC designed for use in a multi-anode photomultiplier system with very large dynamic range and low-noise requirements. Each of the four input signals to the ASIC is split equally into three branches by a current conveyor. Each of the three branches is scaled differently: 1:1, 1:8 and 1:80. The signal is read out by a 12 channel low noise/low power high dynamic range charge sensitive preamplifier-shaper circuit (VA4-PMT chip), with simultaneous sample- and-hold, multiplexed analog read-out, calibration facilities. Tests performed in our lab with a PMT are reported in terms of linearity, dynamic range and cross-talk of the system. (5 refs).

  6. Vertical Profiles of Ammonia in the Colorado Front Range: Impacts of Source Region and Meteorology

    Science.gov (United States)

    Tevlin, A.; Kaushik, A.; Noone, D. C.; Ortega, J. V.; Smith, J. N.; Brophy, P.; Kirkland, J.; Link, M. F.; Farmer, D. K.; Wolfe, D. E.; Dube, W. P.; McDuffie, E. E.; Brown, S. S.; Zaragoza, J.; Fischer, E. V.; Murphy, J. G.

    2014-12-01

    Atmospheric ammonia plays an important role in aerosol particle formation and growth, as well as in nitrogen deposition to sensitive ecosystems. However, significant uncertainties are associated with the distribution and strength of emission sources, and many of the processes that control its atmospheric fate are not fully understood. The high density of agricultural and urban sources located in close proximity to more pristine mountainous areas to the west make the Colorado Front Range a unique area for studying atmospheric ammonia. The meteorology of the region, where heavy monsoon rains can be followed by rapid evaporation, can also impact surface-atmosphere partitioning of ammonia. As part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ), vertical profiles of ammonia were measured throughout the boundary layer aboard a moveable platform on the 300 m Boulder Atmospheric Observatory (BAO) tower. Changes in ammonia concentration and its vertical structure were driven not only by changes in wind direction and estimated source region, but also by fluctuations in surface and atmosphere water content. For example, large increases in atmospheric ammonia mixing ratios were observed following rain events. This may be explained by surface-atmosphere exchange of wet-deposited ammonia associated with rapid evaporation following the event, and likely impacts particle formation. This may also play a role in transport from ammonia-rich agricultural areas towards the mountainous regions to the west during periods of upslope flow. The vertical ammonia concentration gradients observed throughout the structured early morning boundary layer also provide insight into the possible causes of early morning spikes in ammonia - a phenomenon that has been well-documented in many other locations. A box model was used to assess the relative importance of surface emissions due to the evaporation of morning dew versus entrainment of ammonia-rich air from above the

  7. The occurrence of alpine permafrost in the Front Range of Colorado

    Science.gov (United States)

    Janke, Jason R.

    2005-04-01

    Permafrost distribution, or ground that remains frozen for at least 2 years, has been modeled using a combination of Geographic Information System (GIS) techniques, Digital Elevation Model (DEM) variables, and land cover in alpine regions of the world. In the Front Range, however, no such empirical models have been developed, and field data are restricted in spatial extent, but rock glaciers are in abundance. Here, I present a probabilistic logistic regression model that is based on topoclimatic information (elevation and aspect) for rock glaciers derived from U.S. Geological Survey (USGS) 10-m DEMs. Classes of land cover, obtained from an Enhanced Thematic Mapper Plus (ETM+) image classification, were assigned weights and were then multiplied by the regression results to refine estimates. The effectiveness of the model was evaluated by comparing mean probability scores with rock glacier activity categories, Mean Annual Air Temperature (MAAT) from climatic stations on Niwot Ridge, and Bottom Temperature of winter Snow (BTS) measurements, while a Monte Carlo simulation was used to detect uncertainty associated with the original DEM. Permafrost scores >50% covered about 8.9% (242 km 2) of the study area (2722 km 2) with the highest scores clustered around Longs and Rowe Peaks. Permafrost locations showed a strong correlation with rock glacier activity classes, the -1.0 °C MAAT isotherm, and BTS measurements less than -3.0 °C. The uncertainty analysis revealed that slight global differences exist between the original and error prone DEM; however, local variations in aspect caused the most uncertainty. These results indicate that the model accurately represents regional distribution of permafrost. Therefore, topoclimatic information from rock glaciers and land cover, when combined with an uncertainty analysis, can effectively be used to map the occurrence of Front Range permafrost, providing an imperative tool for cartographers, planners, and geocryologists.

  8. Ground water occurrence and contributions to streamflow in an alpine catchment, Colorado Front Range

    Science.gov (United States)

    Clow, D.W.; Schrott, L.; Webb, R.; Campbell, D.H.; Torizzo, A.O.; Dornblaser, M.

    2003-01-01

    Ground water occurrence, movement, and its contribution to streamflow were investigated in Loch Vale, an alpine catchment in the Front Range of the Colorado Rocky Mountains. Hydrogeomorphologic mapping, seismic refraction measurements, and porosity and permeability estimates indicate that talus slopes are the primary ground water reservoir, with a maximum storage capacity that is equal to, or greater than, total annual discharge from the basin (5.4 ± 0.8 × 106 m3). Although snowmelt and glacial melt provide the majority of annual water flux to the basin, tracer tests and gauging along a stream transect indicate that ground water flowing from talus can account for ≥75% of streamflow during storms and the winter base flow period. The discharge response of talus springs to storms and snowmelt reflects rapid transmittal of water through coarse debris at the talus surface and slower release of water from finer-grained sediments at depth.Ice stored in permafrost (including rock glaciers) is the second largest ground water reservoir in Loch Vale; it represents a significant, but seldom recognized, ground water reservoir in alpine terrain. Mean annual air temperatures are sufficiently cold to support permafrost above 3460 m; however, air temperatures have increased 1.1° to 1.4°C since the early 1990s, consistent with long-term (1976–2000) increases in air temperature measured at other high-elevation sites in the Front Range, European Alps, and Peruvian Andes. If other climatic factors remain constant, the increase in air temperatures at Loch Vale is sufficient to increase the lower elevational limit of permafrost by 150 to 190 m. Although this could cause a short-term increase in streamflow, it may ultimately result in decreased flow in the future.

  9. Aerosol optical extinction during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) 2014 summertime field campaign, Colorado, USA

    National Research Council Canada - National Science Library

    Justin H Dingle; Eric C Apel; Teresa L Campos; Alan J Hills; Rebecca S Hornbrook; Denise D Montzka; John B Nowak; Joseph R Roscioli

    2016-01-01

      Summertime aerosol optical extinction (βext) was measured in the Colorado Front Range and Denver metropolitan area as part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ...

  10. Stray light assessment and mitigation for the DESI front-end optical system

    Science.gov (United States)

    Miller, Timothy N.; Lampton, Michael; Besuner, Robert W.; Sholl, Michael J.; Liang, Ming; Ellis, Scott

    2016-08-01

    The Dark Energy Spectroscopic Instrument (DESI) is under construction to measure the expansion history of the Universe, using the Baryon Acoustic Oscillation technique and the growth of structure using redshift-space distortions (RSD). The spectra of 40 million galaxies over 14000 square degrees will be measured during the life of the experiment. A new prime focus corrector for the KPNO Mayall telescope will deliver light to 5000 fiber optic positioners. The fibers in turn feed ten broad-band spectrographs. We will describe modeling and mitigation of stray light within the front end of DESI, consisting of the Mayall telescope and the corrector assembly. This includes the creation of a stray light model, quantitative analysis of the unwanted light at the corrector focal surface, identification of the main scattering sources, and a description of mitigation strategies to remove the sources.

  11. Combined front and back diffraction gratings for broad band light trapping in thin film solar cell.

    Science.gov (United States)

    Meng, Xianqin; Drouard, Emmanuel; Gomard, Guillaume; Peretti, Romain; Fave, Alain; Seassal, Christian

    2012-09-10

    In this paper, we present the integration of combined front and back 1D and 2D diffraction gratings with different periods, within thin film photovoltaic solar cells based on crystalline silicon layers. The grating structures have been designed considering both the need for incident light absorption enhancement and the technological feasibility. Long wavelength absorption is increased thanks to the long period (750 nm) back grating, while the incident light reflection is reduced by using a short period (250 nm) front grating. The simulated short circuit current in a solar cell combining a front and a back grating structures with a 1.2 µm thick c-Si layer, together with the back electrode and TCO layers, is increased up to 30.3 mA/cm2, compared to 18.4 mA/cm2 for a reference stack, as simulated using the AM1.5G solar spectrum intensity distribution from 300 nm to 1100 nm, and under normal incidence.

  12. CMOS Receiver Front-ends for Gigabit Short-Range Optical Communications

    CERN Document Server

    Aznar, Francisco; Calvo Lopez, Belén

    2013-01-01

    This book describes optical receiver solutions integrated in standard CMOS technology, attaining high-speed short-range transmission within cost-effective constraints.  These techniques support short reach applications, such as local area networks, fiber-to-the-home and multimedia systems in cars and homes. The authors show how to implement the optical front-end in the same technology as the subsequent digital circuitry, leading to integration of the entire receiver system in the same chip.  The presentation focuses on CMOS receiver design targeting gigabit transmission along a low-cost, standardized plastic optical fiber up to 50m in length.  This book includes a detailed study of CMOS optical receiver design – from building blocks to the system level. Reviews optical communications, including long-haul transmission systems and emerging applications focused on short-range; Explains necessary fundamentals, such as characteristics of a data signal, system requirements affecting receiver design and key par...

  13. Gene expression under thermal stress varies across a geographical range expansion front.

    Science.gov (United States)

    Lancaster, Lesley T; Dudaniec, Rachael Y; Chauhan, Pallavi; Wellenreuther, Maren; Svensson, Erik I; Hansson, Bengt

    2016-03-01

    Many ectothermic species are currently expanding their distributions polewards due to anthropogenic global warming. Molecular genetic mechanisms facilitating range expansion under these conditions are largely unknown, but understanding these could help mitigate expanding pests and disease vectors, or help explain why some species fail to track changing climates. Here, using RNA-seq data, we examine genomewide changes in gene expression under heat and cold stress in the range-expanding damselfly Ischnura elegans in northern Europe. We find that both the number of genes involved and levels of gene expression under heat stress have become attenuated during the expansion, consistent with a previously reported release from selection on heat tolerances as species move polewards. Genes upregulated under cold stress differed between core and edge populations, corroborating previously reported rapid adaptation to cooler climates at the expansion front. Expression of sixty-nine genes exhibited a region x treatment effect; these were primarily upregulated in response to heat stress in core populations but in response to cold stress at the range edge, suggesting that some cellular responses originally adapted to heat stress may switch to cold-stress functionality upon encountering novel thermal selection regimes during range expansion. Transcriptional responses to thermal stress involving heat-shock and neural function genes were largely geographically conserved, while retrotransposon, regulatory, muscle function and defence gene expression patterns were more variable. Flexible mechanisms of cold-stress response and the ability of some genes to shift their function between heat and cold stress might be key mechanisms facilitating rapid poleward expansion in insects. © 2016 John Wiley & Sons Ltd.

  14. Recursion relations for multi-gluon off-shell amplitudes on the light-front and Wilson lines

    Directory of Open Access Journals (Sweden)

    C. Cruz-Santiago

    2015-06-01

    Full Text Available We analyze the off-shell scattering amplitudes in the framework of the light-front perturbation theory. It is shown that the previously derived recursion relation between tree level off-shell amplitudes in this formalism actually resums whole classes of graphs into a Wilson line. More precisely, we establish a correspondence between the light-front methods for the computation of the off-shell amplitudes and the approach which makes use of the matrix elements of straight infinite Wilson lines, which are manifestly gauge invariant objects. Furthermore, since it is needed to explicitly verify the gauge invariance of light-front amplitudes, it is demonstrated that the Ward identities in this framework need additional instantaneous terms in the light-front graphs.

  15. Sivers and cos 2 ϕ asymmetries in semi-inclusive deep inelastic scattering in light-front holographic model

    Science.gov (United States)

    Maji, Tanmay; Chakrabarti, Dipankar; Mukherjee, Asmita

    2018-01-01

    The spin asymmetries in SIDIS associated with T -odd TMDs are presented in a light-front quark-diquark model of a proton. To incorporate the effects of the final-state interaction, the light front wave functions are modified to have a phase factor which is essential to have Sivers or Boer-Mulders functions. The Sivers and Boer-Mulder asymmetries are compared with HERMES and COMPASS data.

  16. Integrating soils and geomorphology in mountains - An example from the Front Range of Colorado

    Science.gov (United States)

    Birkeland, P.W.; Shroba, R.R.; Burns, S.F.; Price, A.B.; Tonkin, P.J.

    2003-01-01

    Soil distribution in high mountains reflects the impact of several soil-forming factors. Soil geomorphologists use key pedological properties to estimate ages of Quaternary deposits of various depositional environments, estimate long-term stability and instability of landscapes, and make inferences on past climatic change. Once the influence of the soil-forming factors is known, soils can be used to help interpret some aspects of landscape evolution that otherwise might go undetected. The Front Range of Colorado rises from the plains of the Colorado Piedmont at about 1700 m past a widespread, dissected Tertiary erosion surface between 2300 and 2800 m up to an alpine Continental Divide at 3600 to over 4000 m. Pleistocene valley glaciers reached the western edge of the erosion surface. Parent rocks are broadly uniform (granitic and gneissic). Climate varies from 46 cm mean annual precipitation (MAP) and 11 ??C mean annual temperature (MAT) in the plains to 102 cm and -4 ??C, respectively, near the range crest. Vegetation follows climate with grassland in the plains, forest in the mountains, and tundra above 3450 m. Soils reflect the bioclimatic transect from plains to divide: A/Bw or Bt/Bk or K (grassland) to A/E/Bw or Bt/C (forest) to A/Bw/C (tundra). Corresponding soil pH values decrease from 8 to less than 5 with increasing elevation. The pedogenic clay minerals dominant in each major vegetation zone are: smectite (grassland), vermiculite (forest), and 1.0-1.8 nm mixed-layer clays (tundra). Within the lower forested zone, the topographic factor (aspect) results in more leached, colder soils, with relatively thin O horizons, well-expressed E horizons and Bt horizons (Alfisols) on N-facing slopes, whereas soils with thicker A horizons, less developed or no E horizons, and Bw or Bt horizons (Mollisols) are more common on S-facing slopes. The topographic factor in the tundra results in soil patterns as a consequence of wind-redistributed snow and the amount of time it

  17. Radiative Decays of Scalar Mesons in Light-Front Quark Model

    Science.gov (United States)

    Dewitt, Martin; Choi, Ho-Meoyng; Ji, Chueng-Ryong

    2003-04-01

    It is currently thought that the difficulty in experimentally identifying the light scalar glueball results from the fact that it tends to mix with nearby conventional scalar mesons. Therefore, the glueball's presence can only be inferred from the behavior of the experimentally observed (mixed) scalar states. Here, we present relativistic light-front quark model calculations of absolute widths for the radiative decay processes Scalar[0^++] → γγ, Scalar[0^++]→γ Vector[1^-], and Vector[1^-]→γ Scalar[0^++] which incorporate the effects of glueball-q barq mixing. The mixed physical states are assumed to be the f_0(1370), the f_0(1500), and the f_0(1710). The n barn, s bars, and gg content of each of the physical states is taken from the mass mixing matrix calculations of other works. These flavor/glue wavefunctions are then used in conjunction with light-front spin-space wavefunctions to compute transition form factors for the decay processes mentioned above. In the q^2→ 0 limit the form factors are used to determine the corresponding decay widths. Our results are compared with available experimental data as well as the results of a recent non-relativistic model calculation of the process Scalar[0^++]→γ Vector[1^-].

  18. Symmetric multivariate polynomials as a basis for three-boson light-front wave functions.

    Science.gov (United States)

    Chabysheva, Sophia S; Elliott, Blair; Hiller, John R

    2013-12-01

    We develop a polynomial basis to be used in numerical calculations of light-front Fock-space wave functions. Such wave functions typically depend on longitudinal momentum fractions that sum to unity. For three particles, this constraint limits the two remaining independent momentum fractions to a triangle, for which the three momentum fractions act as barycentric coordinates. For three identical bosons, the wave function must be symmetric with respect to all three momentum fractions. Therefore, as a basis, we construct polynomials in two variables on a triangle that are symmetric with respect to the interchange of any two barycentric coordinates. We find that, through the fifth order, the polynomial is unique at each order, and, in general, these polynomials can be constructed from products of powers of the second- and third-order polynomials. The use of such a basis is illustrated in a calculation of a light-front wave function in two-dimensional ϕ(4) theory; the polynomial basis performs much better than the plane-wave basis used in discrete light-cone quantization.

  19. Alpine debris flows triggered by a 28 July 1999 thunderstorm in the central Front Range, Colorado

    Science.gov (United States)

    Godt, Jonathan W.; Coe, Jeffrey A.

    2007-02-01

    On 28 July 1999, about 480 alpine debris flows were triggered by an afternoon thunderstorm along the Continental Divide in Clear Creek and Summit counties in the central Front Range of Colorado. The thunderstorm produced about 43 mm of rain in 4 h, 35 mm of which fell in the first 2 h. Several debris flows triggered by the storm impacted Interstate Highway 70, U.S. Highway 6, and the Arapahoe Basin ski area. We mapped the debris flows from color aerial photography and inspected many of them in the field. Three processes initiated debris flows. The first process initiated 11% of the debris flows and involved the mobilization of shallow landslides in thick, often well vegetated, colluvium. The second process, which was responsible for 79% of the flows, was the transport of material eroded from steep unvegetated hillslopes via a system of coalescing rills. The third, which has been termed the "firehose effect," initiated 10% of the debris flows and occurred where overland flow became concentrated in steep bedrock channels and scoured debris from talus deposits and the heads of debris fans. These three processes initiated high on steep hillsides (> 30°) in catchments with small contributing areas (material along their paths.

  20. Wildfire impacts on soil-water retention in the Colorado Front Range, United States

    Science.gov (United States)

    Ebel, Brian A.

    2012-01-01

    This work examined the plot-scale differences in soil-water retention caused by wildfire in the area of the 2010 Fourmile Canyon Fire in the Colorado Front Range, United States. We measured soil-water retention curves on intact cores and repacked samples, soil particle-size distributions, and organic matter content. Estimates were also made of plant-available water based on the soil-water retention curves. Parameters for use in soil-hydraulic property models were estimated; these parameters can be used in unsaturated flow modeling for comparing burned and unburned watersheds. The primary driver for measured differences in soil-water retention in burned and unburned soils was organic matter content and not soil-particle size distribution. The tendency for unburned south-facing soils to have greater organic matter content than unburned north-facing soils in this field area may explain why unburned south-facing soils had greater soil-water retention than unburned north-facing soils. Our results suggest that high-severity wildfire can “homogenize” soil-water retention across the landscape by erasing soil-water retention differences resulting from organic matter content, which for this site may be affected by slope aspect. This homogenization could have important implications for ecohydrology and plant succession/recovery in burned areas, which could be a factor in dictating the window of vulnerability of the landscape to flash floods and erosion that are a common consequence of wildfire.

  1. Metagenomic profiling of historic Colorado Front Range flood impact on distribution of riverine antibiotic resistance genes

    Science.gov (United States)

    Garner, Emily; Wallace, Joshua S.; Argoty, Gustavo Arango; Wilkinson, Caitlin; Fahrenfeld, Nicole; Heath, Lenwood S.; Zhang, Liqing; Arabi, Mazdak; Aga, Diana S.; Pruden, Amy

    2016-12-01

    Record-breaking floods in September 2013 caused massive damage to homes and infrastructure across the Colorado Front Range and heavily impacted the Cache La Poudre River watershed. Given the unique nature of this watershed as a test-bed for tracking environmental pathways of antibiotic resistance gene (ARG) dissemination, we sought to determine the impact of extreme flooding on ARG reservoirs in river water and sediment. We utilized high-throughput DNA sequencing to obtain metagenomic profiles of ARGs before and after flooding, and investigated 23 antibiotics and 14 metals as putative selective agents during post-flood recovery. With 277 ARG subtypes identified across samples, total bulk water ARGs decreased following the flood but recovered to near pre-flood abundances by ten months post-flood at both a pristine site and at a site historically heavily influenced by wastewater treatment plants and animal feeding operations. Network analysis of de novo assembled sequencing reads into 52,556 scaffolds identified ARGs likely located on mobile genetic elements, with up to 11 ARGs per plasmid-associated scaffold. Bulk water bacterial phylogeny correlated with ARG profiles while sediment phylogeny varied along the river’s anthropogenic gradient. This rare flood afforded the opportunity to gain deeper insight into factors influencing the spread of ARGs in watersheds.

  2. Unpolarized and polarized densities based on a light-front quark-diquark model

    Science.gov (United States)

    Nikkhoo, Negin Sattary; Shojaei, Mohammad Reza

    2017-06-01

    In this paper, we calculate the proton and neutron unpolarized and transversely polarized densities. We use the light-front wave function (LFWF), which at an initial scale is constrained by the soft-wall anti-de Sitter (AdS) QCD model, for calculating the Dirac and Pauli form factors which transverse densities are in terms of these form factors. Also, we use these form factors for calculating the flavor separated results for the proton and neutron electromagnetic form factors and calculate u and d quark unpolarized and transversely polarized densities. Finally, we compare our results with other previous parametrizations.

  3. Imaging dynamical chiral-symmetry breaking: pion wave function on the light front.

    Science.gov (United States)

    Chang, Lei; Cloët, I C; Cobos-Martinez, J J; Roberts, C D; Schmidt, S M; Tandy, P C

    2013-03-29

    We project onto the light front the pion's Poincaré-covariant Bethe-Salpeter wave function obtained using two different approximations to the kernels of quantum chromodynamics' Dyson-Schwinger equations. At an hadronic scale, both computed results are concave and significantly broader than the asymptotic distribution amplitude, φ(π)(asy)(x)=6x(1-x); e.g., the integral of φ(π)(x)/φ(π)(asy)(x) is 1.8 using the simplest kernel and 1.5 with the more sophisticated kernel. Independent of the kernels, the emergent phenomenon of dynamical chiral-symmetry breaking is responsible for hardening the amplitude.

  4. A high dynamic range programmable CMOS front-end filter with a tuning range from 1850 to 2400 MHz

    DEFF Research Database (Denmark)

    Christensen, Kåre Tais; Lee, Thomas H.; Bruun, Erik

    2005-01-01

    This paper presents a highly programmable front-end filter and amplifier intended to replace SAW filters and low noise amplifiers (LNA) in multi-mode direct conversion radio receivers. The filter has a 42 MHz bandwidth, is tunable from 1850 to 2400 MHz, achieves a 5.8 dB NF, -25 dBm in-band 1-d...

  5. Stream power framework for predicting geomorphic change: The 2013 Colorado Front Range flood

    Science.gov (United States)

    Yochum, Steven E.; Sholtes, Joel S.; Scott, Julian A.; Bledsoe, Brian P.

    2017-09-01

    The Colorado Front Range flood of September 2013 induced a diverse range of geomorphic changes along numerous stream corridors, providing an opportunity to assess responses to a large flood in a semiarid landscape. We defined six classes of geomorphic change related to peak unit stream power and valley confinement for 531 stream reaches over 226 km, spanning a gradient of channel scales and slope. Geomorphic change was generally driven by erosion of channel margins in confined reaches and by a combination of deposition and erosion in unconfined reaches. The magnitude of geomorphic change typically increased with unit stream power (ω), with greater responses observed in unconfined channels. Cumulative logit modeling indicated that total stream power or unit stream power, unit stream power gradient, and valley confinement are significant predictors of geomorphic response for this flood event. Based on this dataset, thresholds for geomorphic adjustment were defined. For channel slopes 230 W/m2 (16 lb/ft-s; at least 10% of the investigated sites experienced substantial channel widening) and a credible potential for avulsions, braiding, and loss of adjacent road embankments associated with ω > 480 W/m2 (33 lb/ft-s; at least 10% of the investigated sites experienced such geomorphic change). Infrequent to numerous eroded banks were very likely with ω > 700 W/m2 (48 lb/ft-s), with substantial channel widening or major geomorphic change shifting from credible to likely. Importantly, in reaches where there were large reductions in ω as the valley form shifted from confined to relatively unconfined, large amounts of deposition-induced, reach-scale geomorphic change occurred in some locations at relatively low ω. Additionally, alluvial channels with slopes > 3% had greater resistance to geomorphic change, likely caused by armoring by larger bed material and increased flow resistance from enhanced bedforms. Finally, we describe how these results can potentially be used by

  6. Influence of front light configuration on the visual conspicuity of motorcycles.

    Science.gov (United States)

    Pinto, Maria; Cavallo, Viola; Saint-Pierre, Guillaume

    2014-01-01

    A recent study (Cavallo and Pinto, 2012) showed that daytime running lights (DRLs) on cars create "visual noise" that interferes with the lighting of motorcycles and affects their visual conspicuity. In the present experiment, we tested three conspicuity enhancements designed to improve motorcycle detectability in a car-DRL environment: a triangle configuration (a central headlight plus two lights located on the rearview mirrors), a helmet configuration (a light located on the motorcyclist's helmet in addition to the central headlight), and a single central yellow headlight. These three front-light configurations were evaluated in comparison to the standard configuration (a single central white headlight). Photographs representing complex urban traffic scenes were presented briefly (for 250ms). The results revealed better motorcycle-detection performance for both the yellow headlight and the helmet configuration than for the standard configuration. The findings suggest some avenues for defining a new visual signature for motorcycles in car-DRL environments. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. WATER SPOTTERS: Water, energy, isotopes and experiential learning in the Colorado Front Range

    Science.gov (United States)

    Noone, D. C.; Berkelhammer, M. B.; Raudzens Bailey, A.; Buhr, S. M.; Smith, L. K.

    2011-12-01

    Providing students with tangible examples of the two-way interaction between human society and the climate system is a pressing challenge. Water is at the core of many issues in environmental change from local to global scales. In climate research, there are significant uncertainties in the role water plays in the climate system. "Water" can also act as a central theme that provides opportunities for science education at all levels. WATER SPOTTERS takes advantage of the prominent agricultural landscape of the region, which is a poignant example of how society influences the climate through irrigation, evaporation/transpiration and run-off and whose productivity is influenced by the climate system. Both natural grasslands and alpine ecosystems in the surrounding regions serve as examples of the native landscape. The centerpiece of this project is a 300m tower that is fully implemented with gas sampling lines and micrometeorological equipment to study the energy and water budgets of the region. Middle Schools that surround this site, many of which exist in visual contact with the tall tower, are provided with meteorological stations, which provide rainfall rates, temperature, humidity and radiation data. In coordination with the St Vrain Valley School District MESA (Math Engineering Science Achievement) program, students collect rain water samples that are analyzed and used as a core component of the research goals. The students use the weather stations as a way to directly explore their local climatology and provide data that is needed in research. We present an overview of the curriculum goals and associated physical infrastructure designed for middle school students in the Colorado Front Range to explore their local water cycle using water isotopes. The fixed infrastructure at the schools and tall tower are supplemented by mobile instruments such as an automated precipitation collector and snowflake photography system, which both fulfill science needs and provide

  8. PACE3 a large dynamic range analog memory front-end ASIC assembly for the charge readout of silicon sensors

    CERN Document Server

    Aspell, P; Bialas, W; Bloch, P; Dupanloup, M; Go A; Kloukinas, K; Manthos, N; Moraes, D; Morrissey, Q; Peisert, Anna; Reynaud, S; Sidiropoulos, G; Tcheremoukhine, A; Vichoudis, P

    2006-01-01

    This paper describes the architecture of PACE3 and the key design parameters for a large dynamic range front-end amplification and low noise analog memory. Measured results from PACE3 are presented characterizing the chip's performance in terms of gain, pulse shaping characteristics, noise, power consumption and radiation tolerance with respect to total ionizing dose and robustness to single event upsets (SEU).

  9. 75 FR 9893 - Adequacy Determination for the Denver Metro Area and North Front Range 8-Hour Ozone Attainment...

    Science.gov (United States)

    2010-03-04

    ... North Front Range Metropolitan Planning Organization (NFR MPO), the Colorado Department of... budgets for future transportation conformity determinations once this finding becomes effective. DATES: This finding is effective March 19, 2010. FOR FURTHER INFORMATION CONTACT: Tim Russ, Air Program (8P-AR...

  10. Light Detection and Ranging Point Cloud Data: 2000 - Present

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — LIDAR (Light Detection and Ranging) discrete-return point cloud data are available in the American Society for Photogrammetry and Remote Sensing (ASPRS) LAS format....

  11. Double parton scattering: A study of the effective cross section within a Light-Front quark model

    Directory of Open Access Journals (Sweden)

    Matteo Rinaldi

    2016-01-01

    Full Text Available We present a calculation of the effective cross section σeff, an important ingredient in the description of double parton scattering in proton–proton collisions. Our theoretical approach makes use of a Light-Front quark model as a framework to calculate the double parton distribution functions at low-resolution scale. QCD evolution is implemented to reach the experimental scale. The obtained values of σeff in the valence region are consistent with the present experimental scenario, in particular with the sets of data which include the same kinematical range. However the result of the complete calculation shows a dependence of σeff on xi, a feature not easily seen in the available data, probably because of their low accuracy. Measurements of σeff in restricted xi regions are addressed to obtain indications on double parton correlations, a novel and interesting aspect of the three dimensional structure of the nucleon.

  12. Higher measured than modeled ozone production at increased NOx levels in the Colorado Front Range

    Science.gov (United States)

    Baier, Bianca C.; Brune, William H.; Miller, David O.; Blake, Donald; Long, Russell; Wisthaler, Armin; Cantrell, Christopher; Fried, Alan; Heikes, Brian; Brown, Steven; McDuffie, Erin; Flocke, Frank; Apel, Eric; Kaser, Lisa; Weinheimer, Andrew

    2017-09-01

    Chemical models must correctly calculate the ozone formation rate, P(O3), to accurately predict ozone levels and to test mitigation strategies. However, air quality models can have large uncertainties in P(O3) calculations, which can create uncertainties in ozone forecasts, especially during the summertime when P(O3) is high. One way to test mechanisms is to compare modeled P(O3) to direct measurements. During summer 2014, the Measurement of Ozone Production Sensor (MOPS) directly measured net P(O3) in Golden, CO, approximately 25 km west of Denver along the Colorado Front Range. Net P(O3) was compared to rates calculated by a photochemical box model that was constrained by measurements of other chemical species and that used a lumped chemical mechanism and a more explicit one. Median observed P(O3) was up to a factor of 2 higher than that modeled during early morning hours when nitric oxide (NO) levels were high and was similar to modeled P(O3) for the rest of the day. While all interferences and offsets in this new method are not fully understood, simulations of these possible uncertainties cannot explain the observed P(O3) behavior. Modeled and measured P(O3) and peroxy radical (HO2 and RO2) discrepancies observed here are similar to those presented in prior studies. While a missing atmospheric organic peroxy radical source from volatile organic compounds co-emitted with NO could be one plausible solution to the P(O3) discrepancy, such a source has not been identified and does not fully explain the peroxy radical model-data mismatch. If the MOPS accurately depicts atmospheric P(O3), then these results would imply that P(O3) in Golden, CO, would be NOx-sensitive for more of the day than what is calculated by models, extending the NOx-sensitive P(O3) regime from the afternoon further into the morning. These results could affect ozone reduction strategies for the region surrounding Golden and possibly other areas that do not comply with national ozone regulations

  13. Higher measured than modeled ozone production at increased NOx levels in the Colorado Front Range

    Directory of Open Access Journals (Sweden)

    B. C. Baier

    2017-09-01

    Full Text Available Chemical models must correctly calculate the ozone formation rate, P(O3, to accurately predict ozone levels and to test mitigation strategies. However, air quality models can have large uncertainties in P(O3 calculations, which can create uncertainties in ozone forecasts, especially during the summertime when P(O3 is high. One way to test mechanisms is to compare modeled P(O3 to direct measurements. During summer 2014, the Measurement of Ozone Production Sensor (MOPS directly measured net P(O3 in Golden, CO, approximately 25 km west of Denver along the Colorado Front Range. Net P(O3 was compared to rates calculated by a photochemical box model that was constrained by measurements of other chemical species and that used a lumped chemical mechanism and a more explicit one. Median observed P(O3 was up to a factor of 2 higher than that modeled during early morning hours when nitric oxide (NO levels were high and was similar to modeled P(O3 for the rest of the day. While all interferences and offsets in this new method are not fully understood, simulations of these possible uncertainties cannot explain the observed P(O3 behavior. Modeled and measured P(O3 and peroxy radical (HO2 and RO2 discrepancies observed here are similar to those presented in prior studies. While a missing atmospheric organic peroxy radical source from volatile organic compounds co-emitted with NO could be one plausible solution to the P(O3 discrepancy, such a source has not been identified and does not fully explain the peroxy radical model–data mismatch. If the MOPS accurately depicts atmospheric P(O3, then these results would imply that P(O3 in Golden, CO, would be NOx-sensitive for more of the day than what is calculated by models, extending the NOx-sensitive P(O3 regime from the afternoon further into the morning. These results could affect ozone reduction strategies for the region surrounding Golden and possibly other areas that do not comply with national ozone

  14. Sources and Seasonality of Volatile Organic Compounds in the Northern Front Range Metropolitan Area

    Science.gov (United States)

    Abeleira, A.; Pollack, I. B.; Sive, B. C.; Zaragoza, J.; Lindaas, J.; Fischer, E. V.; Farmer, D.

    2016-12-01

    The Northern Front Range Metropolitan Area (NFRMA) of Colorado, with a growing population of over 3 million, was deemed an ozone (O3) nonattainment area (NAA) in 2008 despite continued work on NOx reductions. Ground-level O3 is produced from photochemical catalytic cycles initiated by the OH oxidation of volatile organic compounds (VOCs), and propagated through reactions involving peroxy (HO2+RO2) and NOx (NO + NO2) radicals. We measured a suite of speciated VOCs during two 8-week deployments (March-May 2015, July-September 2015) at the Boulder Atmospheric Observatory in Erie, CO. The spring deployment overlapped with the NOAA SONGNEX (Shale Oil and Natural Gas Nexus) campaign. The BAO site lies at an urban-rural interface in the NFRMA with multiple urban centers surrounding the site, a major interstate highway within 2 miles, local suburban development in Erie, agricultural operations in the surrounding counties, and recent rapid expansion of oil and gas development in adjacent Weld County. VOCs were measured hourly with a custom-built online gas chromatography system along with measurements of O3, NOx, PAN, CO, and CH4. VOC measurements included C2-C8 hydrocarbons (NMHCs), C1-C5 alkyl nitrates, C1-C2 halocarbons, and several oxygenated species (OVOCs: methyl ethyl ketone, acetone, acetaldehyde). Using Positive Matrix Factorization (PMF) we have identified four distinct VOC sources in the spring and five in the summer: 1) Oil and Natural Gas (ONG, e.g. C2 - C5 alkanes), 2) Traffic (e.g. ethyne & aromatics), 3) Background species (e.g. long-lived halogenated species), 4) Secondary production (e.g. C3-C5 alkyl nitrates & OVOCs), and for summer 5) Biogenic (e.g. isoprene). Using the source factors generated from the PMF analysis we calculated the VOC reactivity (VOCr) of each source. For both seasons, the ONG factor dominates VOCr in the mornings. In spring afternoons, a combination of background species and secondary products make up a large percentage of VOCr as

  15. ρ meson unpolarized generalized parton distributions with a light-front constituent quark model

    Science.gov (United States)

    Sun, Bao-Dong; Dong, Yu-Bing

    2017-08-01

    We study ρ meson unpolarized generalized parton distributions based on a light-front constituent quark model where the quark-antiquark-meson vertex is constructed under the symmetric loop momentum convention. The form factors and some other low-energy observables of the ρ meson are calculated. Moreover, the contributions to the form factors and generalized parton distributions from the valence and nonvalence regimes are discussed and analyzed in detail. In the forward limit, the usual structure functions are estimated as well. In addition, by evolving the moments of the obtained structure functions to the scale of the lattice calculation, we give the factorization scale of our quark model. It is found that the present phenomenological model is reasonable to describe the general properties of ρ meson.

  16. Basis of symmetric polynomials for many-boson light-front wave functions.

    Science.gov (United States)

    Chabysheva, Sophia S; Hiller, John R

    2014-12-01

    We provide an algorithm for the construction of orthonormal multivariate polynomials that are symmetric with respect to the interchange of any two coordinates on the unit hypercube and are constrained to the hyperplane where the sum of the coordinates is one. These polynomials form a basis for the expansion of bosonic light-front momentum-space wave functions, as functions of longitudinal momentum, where momentum conservation guarantees that the fractions are on the interval [0,1] and sum to one. This generalizes earlier work on three-boson wave functions to wave functions for arbitrarily many identical bosons. A simple application in two-dimensional ϕ(4) theory illustrates the use of these polynomials.

  17. The Light-Front Schrödinger Equation and Determination of the Perturbative QCD Scale from Color Confinement

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J. [SLAC National Accelerator Lab., Menlo Park, CA (United States); de Teramond, Guy F. [Univ. of Costa Rica, San Pedro (Costa Rica); Deur, Alexandre P. [Jefferson La.b, Newport News, VA (United States); Dosch, Hans G. [Institut fur Theoretische Physik, Heidelberg (Germany)

    2015-09-01

    The valence Fock-state wavefunctions of the light-front QCD Hamiltonian satisfy a relativistic equation of motion with an effective confining potential U which systematically incorporates the effects of higher quark and gluon Fock states. If one requires that the effective action which underlies the QCD Lagrangian remains conformally invariant and extends the formalism of de Alfaro, Fubini and Furlan to light front Hamiltonian theory, the potential U has a unique form of a harmonic oscillator potential, and a mass gap arises. The result is a nonperturbative relativistic light-front quantum mechanical wave equation which incorporates color confinement and other essential spectroscopic and dynamical features of hadron physics, including a massless pion for zero quark mass and linear Regge trajectories with the same slope in the radial quantum number n and orbital angular momentum L. Only one mass parameter κ appears. Light-front holography thus provides a precise relation between the bound-state amplitudes in the fifth dimension of AdS space and the boost-invariant light-front wavefunctions describing the internal structure of hadrons in physical space-time. We also show how the mass scale κ underlying confinement and hadron masses determines the scale Λ{ovr MS} controlling the evolution of the perturbative QCD coupling. The relation between scales is obtained by matching the nonperturbative dynamics, as described by an effective conformal theory mapped to the light-front and its embedding in AdS space, to the perturbative QCD regime computed to four-loop order. The result is an effective coupling defined at all momenta. The predicted value Λ{ovr MS}=0.328±0.034 GeV is in agreement with the world average 0.339±0.010 GeV. The analysis applies to any renormalization scheme.

  18. Merging long range transportation planning with public health: a case study from Utah's Wasatch Front.

    Science.gov (United States)

    Burbidge, Shaunna K

    2010-01-01

    US transportation systems have been identified as a problem for public health, as they often encourage automobile transportation and discourage physical activity. This paper provides a case study examination of the Public Health Component of the Wasatch Front Regional Council's Regional Transportation Plan. This plan provides an example of what transportation planners at Utah's largest metropolitan planning organization (MPO) are doing to encourage physical activity through transportation. Existing active living research was used to guide recommendations using a process that included a comprehensive literature review and a review of existing state programs, advisory group and stakeholder meetings, and policy recommendations based on existing local conditions. Stakeholders from a diversity of background and interests came together with one common goal: to improve public health. Based on this collaborative process, nine policy approaches were specifically recommended for approval and integration in the Wasatch Front Regional Transportation Plan. By using current research as a guide and integrating a variety of interests, the Wasatch Front Regional Council is setting a new standard for a collaborative multi-modal focus in transportation planning, which can be replicated nationwide.

  19. [Measurement of scotopic pupils comparing green light test and wave-front analyser WASCA].

    Science.gov (United States)

    Schulze, S; Sekundo, W

    2005-05-01

    The aim of this study was to compare the accuracy and the reproducibility of scotopic pupil measurements using 2 different methods. Scotopic pupil diameter was measured in 56 eyes of 28 volunteers and the results were compared between the green light test at the slit lamp (Haag-Streit, Switzerland) and the automatic measurements of the wave-front analyser WASCA (Carl-Zeiss-Meditec) by 2 independent examiners. Non-parametric sign test as well as All Pairwise Multiple Comparison Procedures (Student-Newman-Keuls method) were performed for the comparison of means for each individual eye as well as the results of both eyes tested by both examiners. Mean age of the subjects was 34.9 years. The colour of iris was green or blue in 22 cases and brown in 6 cases. REPRODUCIBILITY: For the green light test we found for the first investigator in the right eye a mean pupil diameter of 6.58 mm (SD 0.68). The measurement of the second investigator for the same eye was 6.64 mm (SD 0.61). The left eye values were as follows: 6.36 mm (SD 0.68) and 6.75 mm (SD 0.68). For WASCA we found for the first investigator in the right eye 6.33 mm (SD 0.64) vs. 6.30 mm (SD 0.64) for the second investigator, in the left eye 6.39 mm (SD 0.69) vs. 6.36 mm (SD 0.60). There was a statistically significant difference between the two investigators when the green light test was used (6.47 mm vs. 6.69 mm for both eyes). No difference was found using the WASCA integrated pupillometer (6.35 mm vs. 6.33 mm). There was a significant difference between the means of combined data for both measurement methods: 6.58 mm for the green light test (SD 0.57) vs. 6.34 mm for WASCA (SD 0.62). The integrated pupillometry of the WASCA analyser showed better reproducibility of measurements than the green light test. The green light test measures a slightly larger diameter (in the mean by 0.25 mm) than WASCA. Because of the fair and clinically sufficient reproducibility as well as virtually non-existing additional costs

  20. Quantifying the Contribution of Thermally Driven Recirculation to a High-Ozone Event Along the Colorado Front Range Using Lidar

    Science.gov (United States)

    Sullivan, John T.; McGee, Thomas J.; Langford, Andrew O.; Alvarez, Raul J., II; Senff, Christoph; Reddy, Patrick J.; Thompson, Anne M.; Twigg, Laurence W.; Sumnicht, Grant K.; Lee, Pius; hide

    2016-01-01

    A high-ozone (O3) pollution episode was observed on 22 July 2014 during the concurrent Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) and Front Range Air Pollution and Photochemistry Experiment (FRAPPE) campaigns in northern Colorado. Surface O3 monitors at three regulatory sites exceeded the Environmental Protection Agency (EPA) 2008 National Ambient Air Quality Standard (NAAQS) daily maximum 8h average (MDA8) of 75ppbv. To further characterize the polluted air mass and assess transport throughout the event, measurements are presented from O3 and wind profilers, O3-sondes, aircraft, and surface-monitoring sites. Observations indicate that thermally driven upslope flow was established throughout the Colorado Front Range during the pollution episode. As the thermally driven flow persisted throughout the day, O3 concentrations increased and affected high-elevation Rocky Mountain sites. These observations, coupled with modeling analyses, demonstrate a westerly return flow of polluted air aloft, indicating that the mountain-plains solenoid circulation was established and impacted surface conditions within the Front Range.

  1. Aerosol optical extinction during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) 2014 summertime field campaign, Colorado, USA

    Science.gov (United States)

    Dingle, Justin H.; Vu, Kennedy; Bahreini, Roya; Apel, Eric C.; Campos, Teresa L.; Flocke, Frank; Fried, Alan; Herndon, Scott; Hills, Alan J.; Hornbrook, Rebecca S.; Huey, Greg; Kaser, Lisa; Montzka, Denise D.; Nowak, John B.; Reeves, Mike; Richter, Dirk; Roscioli, Joseph R.; Shertz, Stephen; Stell, Meghan; Tanner, David; Tyndall, Geoff; Walega, James; Weibring, Petter; Weinheimer, Andrew

    2016-09-01

    Summertime aerosol optical extinction (βext) was measured in the Colorado Front Range and Denver metropolitan area as part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) campaign during July-August 2014. An Aerodyne cavity attenuated phase shift particle light extinction monitor (CAPS-PMex) was deployed to measure βext (at average relative humidity of 20 ± 7 %) of submicron aerosols at λ = 632 nm at 1 Hz. Data from a suite of gas-phase instrumentation were used to interpret βext behavior in various categories of air masses and sources. Extinction enhancement ratios relative to CO (Δβext / ΔCO) were higher in aged urban air masses compared to fresh air masses by ˜ 50 %. The resulting increase in Δβext / ΔCO for highly aged air masses was accompanied by formation of secondary organic aerosols (SOAs). In addition, the impacts of aerosol composition on βext in air masses under the influence of urban, natural oil and gas operations (O&G), and agriculture and livestock operations were evaluated. Estimated non-refractory mass extinction efficiency (MEE) values for different air mass types ranged from 1.51 to 2.27 m2 g-1, with the minimum and maximum values observed in urban and agriculture-influenced air masses, respectively. The mass distribution for organic, nitrate, and sulfate aerosols presented distinct profiles in different air mass types. During 11-12 August, regional influence of a biomass burning event was observed, increasing the background βext and estimated MEE values in the Front Range.

  2. Aerosol optical extinction during the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ 2014 summertime field campaign, Colorado, USA

    Directory of Open Access Journals (Sweden)

    J. H. Dingle

    2016-09-01

    Full Text Available Summertime aerosol optical extinction (βext was measured in the Colorado Front Range and Denver metropolitan area as part of the Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ campaign during July–August 2014. An Aerodyne cavity attenuated phase shift particle light extinction monitor (CAPS-PMex was deployed to measure βext (at average relative humidity of 20 ± 7 % of submicron aerosols at λ = 632 nm at 1 Hz. Data from a suite of gas-phase instrumentation were used to interpret βext behavior in various categories of air masses and sources. Extinction enhancement ratios relative to CO (Δβext ∕ ΔCO were higher in aged urban air masses compared to fresh air masses by  ∼  50 %. The resulting increase in Δβext ∕ ΔCO for highly aged air masses was accompanied by formation of secondary organic aerosols (SOAs. In addition, the impacts of aerosol composition on βext in air masses under the influence of urban, natural oil and gas operations (O&G, and agriculture and livestock operations were evaluated. Estimated non-refractory mass extinction efficiency (MEE values for different air mass types ranged from 1.51 to 2.27 m2 g−1, with the minimum and maximum values observed in urban and agriculture-influenced air masses, respectively. The mass distribution for organic, nitrate, and sulfate aerosols presented distinct profiles in different air mass types. During 11–12 August, regional influence of a biomass burning event was observed, increasing the background βext and estimated MEE values in the Front Range.

  3. Fronts, fish, and predators

    Science.gov (United States)

    Belkin, Igor M.; Hunt, George L.; Hazen, Elliott L.; Zamon, Jeannette E.; Schick, Robert S.; Prieto, Rui; Brodziak, Jon; Teo, Steven L. H.; Thorne, Lesley; Bailey, Helen; Itoh, Sachihiko; Munk, Peter; Musyl, Michael K.; Willis, Jay K.; Zhang, Wuchang

    2014-09-01

    Ocean fronts play a key role in marine ecosystems. Fronts shape oceanic landscapes and affect every trophic level across a wide range of spatio-temporal scales, from meters to thousands of kilometers, and from days to millions of years. At some fronts, there is an elevated rate of primary production, whereas at others, plankton is aggregated by advection and by the behavior of organisms moving against gradients in temperature, salinity, light irradiance, hydrostatic pressure and other physico-chemical and biological factors. Lower trophic level organisms - phytoplankton and zooplankton - that are aggregated in sufficient densities, attract organisms from higher trophic levels, from planktivorous schooling fish to squid, large piscivorous fish, seabirds and marine mammals. Many species have critical portions of their life stages or behaviors closely associated with fronts, including spawning, feeding, ontogenetic development, migrations, and other activities cued to frontal dynamics. At different life stages, an individual species or population might be linked to different fronts. The nature and strength of associations between fronts and biota depend on numerous factors such as the physical nature and spatio-temporal scales of the front and the species and their life stages in question. In other words, fronts support many different niches and micro/macro-habitats over a wide range of spatial and temporal scales.

  4. Perspectives of Light-Front Quantized Field Theory: Some New Results

    Energy Technology Data Exchange (ETDEWEB)

    Srivastava, Prem P.

    1999-08-13

    A review of some basic topics in the light-front (LF) quantization of relativistic field theory is made. It is argued that the LF quantization is equally appropriate as the conventional one and that they lead, assuming the microcausality principle, to the same physical content. This is confirmed in the studies on the LF of the spontaneous symmetry breaking (SSB), of the degenerate vacua in Schwinger model (SM) and Chiral SM (CSM), of the chiral boson theory, and of the QCD in covariant gauges among others. The discussion on the LF is more economical and more transparent than that found in the conventional equal-time quantized theory. The removal of the constraints on the LF phase space by following the Dirac method, in fact, results in a substantially reduced number of independent dynamical variables. Consequently, the descriptions of the physical Hilbert space and the vacuum structure, for example, become more tractable. In the context of the Dyson-Wick perturbation theory the relevant propagators in the front form theory are causal. The Wick rotation can then be performed to employ the Euclidean space integrals in momentum space. The lack of manifest covariance becomes tractable, and still more so if we employ, as discussed in the text, the Fourier transform of the fermionic field based on a special construction of the LF spinor. The fact that the hyperplanes x{sup {+-}} = 0 constitute characteristic surfaces of the hyperbolic partial differential equation is found irrelevant in the quantized theory; it seems sufficient to quantize the theory on one of the characteristic hyperplanes.

  5. Toward Realization of 2.4 GHz Balunless Narrowband Receiver Front-End for Short Range Wireless Applications

    Directory of Open Access Journals (Sweden)

    Munir M. El-Desouki

    2015-05-01

    Full Text Available The demand for radio frequency (RF transceivers operating at 2.4 GHz band has attracted considerable research interest due to the advancement in short range wireless technologies. The performance of RF transceivers depends heavily on the transmitter and receiver front-ends. The receiver front-end is comprised of a low-noise amplifier (LNA and a downconversion mixer. There are very few designs that focus on connecting the single-ended output LNA to a double-balanced mixer without the use of on-chip transformer, also known as a balun. The objective of designing such a receiver front-end is to achieve high integration and low power consumption. To meet these requirements, we present the design of fully-integrated 2.4 GHz receiver front-end, consisting of a narrow-band LNA and a double balanced mixer without using a balun. Here, the single-ended RF output signal of the LNA is translated into differential signal using an NMOS-PMOS (n-channel metal-oxide-semiconductor, p-channel metal-oxide-semiconductor transistor differential pair instead of the conventional NMOS-NMOS transistor configuration, for the RF amplification stage of the double-balanced mixer. The proposed receiver circuit fabricated using TSMC 0.18 µm CMOS technology operates at 2.4 GHz and produces an output signal at 300 MHz. The fabricated receiver achieves a gain of 16.3 dB and consumes only 6.74 mW operating at 1.5 V, while utilizing 2.08 mm2 of chip area. Measurement results demonstrate the effectiveness and suitability of the proposed receiver for short-range wireless applications, such as in wireless sensor network (WSN.

  6. Toward Realization of 2.4 GHz Balunless Narrowband Receiver Front-End for Short Range Wireless Applications.

    Science.gov (United States)

    El-Desouki, Munir M; Qasim, Syed Manzoor; BenSaleh, Mohammed S; Deen, M Jamal

    2015-05-07

    The demand for radio frequency (RF) transceivers operating at 2.4 GHz band has attracted considerable research interest due to the advancement in short range wireless technologies. The performance of RF transceivers depends heavily on the transmitter and receiver front-ends. The receiver front-end is comprised of a low-noise amplifier (LNA) and a downconversion mixer. There are very few designs that focus on connecting the single-ended output LNA to a double-balanced mixer without the use of on-chip transformer, also known as a balun. The objective of designing such a receiver front-end is to achieve high integration and low power consumption. To meet these requirements, we present the design of fully-integrated 2.4 GHz receiver front-end, consisting of a narrow-band LNA and a double balanced mixer without using a balun. Here, the single-ended RF output signal of the LNA is translated into differential signal using an NMOS-PMOS (n-channel metal-oxide-semiconductor, p-channel metal-oxide-semiconductor) transistor differential pair instead of the conventional NMOS-NMOS transistor configuration, for the RF amplification stage of the double-balanced mixer. The proposed receiver circuit fabricated using TSMC 0.18 µm CMOS technology operates at 2.4 GHz and produces an output signal at 300 MHz. The fabricated receiver achieves a gain of 16.3 dB and consumes only 6.74 mW operating at 1.5 V, while utilizing 2.08 mm2 of chip area. Measurement results demonstrate the effectiveness and suitability of the proposed receiver for short-range wireless applications, such as in wireless sensor network (WSN).

  7. Influence of front and back grating on light trapping in microcrystalline thin-film silicon solar cells.

    Science.gov (United States)

    Madzharov, Darin; Dewan, Rahul; Knipp, Dietmar

    2011-03-14

    The optics of microcrystalline thin-film silicon solar cells with textured interfaces was investigated. The surface textures lead to scattering and diffraction of the incident light, which increases the effective thickness of the solar cell and results in a higher short circuit current. The aim of this study was to investigate the influence of the frontside and the backside texture on the short circuit current of microcrystalline thin-film silicon solar cells. The interaction of the front and back textures plays a major role in optimizing the overall short circuit current of the solar cell. In this study the front and back textures were approximated by line gratings to simplify the analysis of the wave propagation in the textured solar cell. The influence of the grating period and height on the quantum efficiency and the short circuit current was investigated and optimal grating dimensions were derived. The height of the front and back grating can be used to control the propagation of different diffraction orders in the solar cell. The short circuit current for shorter wavelengths (300-500 nm) is almost independent of the grating dimensions. For intermediate wavelengths (500 nm - 700 nm) the short circuit current is mainly determined by the front grating. For longer wavelength (700 nm to 1100 nm) the short circuit current is a function of the interaction of the front and back grating. An independent adjustment of the grating height of the front and the back grating allows for an increased short circuit current.

  8. Beyond Colorado's Front Range - A new look at Laramide basin subsidence, sedimentation, and deformation in north-central Colorado

    Science.gov (United States)

    Cole, James C.; Trexler, James H.; Cashman, Patricia H.; Miller, Ian M.; Shroba, Ralph R.; Cosca, Michael A.; Workman, Jeremiah B.

    2010-01-01

    This field trip highlights recent research into the Laramide uplift, erosion, and sedimentation on the western side of the northern Colorado Front Range. The Laramide history of the North Park?Middle Park basin (designated the Colorado Headwaters Basin in this paper) is distinctly different from that of the Denver basin on the eastern flank of the range. The Denver basin stratigraphy records the transition from Late Cretaceous marine shale to recessional shoreline sandstones to continental, fluvial, marsh, and coal mires environments, followed by orogenic sediments that span the K-T boundary. Upper Cretaceous and Paleogene strata in the Denver basin consist of two mega-fan complexes that are separated by a 9 million-year interval of erosion/non-deposition between about 63 and 54 Ma. In contrast, the marine shale unit on the western flank of the Front Range was deeply eroded over most of the area of the Colorado Headwaters Basin (approximately one km removed) prior to any orogenic sediment accumulation. New 40Ar-39Ar ages indicate the oldest sediments on the western flank of the Front Range were as young as about 61 Ma. They comprise the Windy Gap Volcanic Member of the Middle Park Formation, which consists of coarse, immature volcanic conglomerates derived from nearby alkalic-mafic volcanic edifices that were forming at about 65?61 Ma. Clasts of Proterozoic granite, pegmatite, and gneiss (eroded from the uplifted core of the Front Range) seem to arrive in the Colorado Headwaters Basin at different times in different places, but they become dominant in arkosic sandstones and conglomerates about one km above the base of the Colorado Headwaters Basin section. Paleocurrent trends suggest the southern end of the Colorado Headwaters Basin was structurally closed because all fluvial deposits show a northward component of transport. Lacustrine depositional environments are indicated by various sedimentological features in several sections within the >3 km of sediment

  9. Reactive nitrogen in Rocky Mountain National Park during the Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ)

    Science.gov (United States)

    Prenni, A. J.; Benedict, K. B.; Evanoski-Cole, A. R.; Zhou, Y.; Sullivan, A.; Day, D.; Sive, B. C.; Zondlo, M. A.; Schichtel, B. A.; Vimont, J.; Collett, J. L., Jr.

    2014-12-01

    The Front Range Air Pollution and Photochemistry Éxperiment (FRAPPÉ) took place in July-August 2014. This collaborative study was aimed at characterizing those processes which control air quality along Colorado's Front Range. Although the study was largely focused on ozone, an additional goal of the study included characterizing contributions from Front Range sources and long-range transport to total reactive nitrogen in Rocky Mountain National Park (ROMO). Import of reactive nitrogen into ROMO and other pristine, high elevation areas has the potential to negatively impact terrestrial and aquatic ecosystems. We present measurements of reactive nitrogen species measured within ROMO during FRAPPÉ, and compare these data to measurements made in the surrounding areas. At our monitoring site in ROMO, co-located with IMPROVE and CASTNet monitoring, measurements of NO, NO2, NOx, NOy, NH3, and total reactive nitrogen (TNx) were made at high time resolution. Additional measurements of NH3, HNO3 and PM2.5 ions were made at hourly resolution using a MARGA and also at 24-hour time resolution using URG denuder-filter pack sampling. Precipitation samples also were collected to quantify wet deposition of ammonium, nitrate, and organic nitrogen. Finally, measurements of organic gases were made using online gas chromatography and proton transfer reaction-mass spectrometry. Preliminary results for ammonia show both a diel pattern, with concentrations increasing each morning, and a strong dependence on wind direction, implicating the importance of transport. Higher concentrations of NOx and NOy also were observed in the daytime, but in general these patterns differed from that of ammonia. Several upslope events were observed during the measurement period during which NOx, NH3, 2-propylnitrate, 2-butylnitrate, ethane, butane, and pentane were observed to increase in concentration along with ozone.

  10. Quantum Field Theory in Two Dimensions: Light-front Versus Space-like Solutions

    Science.gov (United States)

    Martinovic̆, L'ubomír

    2017-07-01

    A few non-perturbative topics of quantum field theory in D=1+1 are studied in both the conventional (SL) and light-front (LF) versions. First, we give a concise review of the recently proposed quantization of the two-dimensional massless LF fields. The LF version of bosonization follows in a simple and natural way including the bosonized form of the Thirring model. As a further application, we demonstrate the closeness of the 2D massless LF quantum fields to conformal field theory (CFT). We calculate several correlation functions including those between the components of the LF energy-momentum tensor and derive the LF version of the Virasoro algebra. Using the Euclidean time variable, we can immediately transform calculated quantities to the (anti)holomorphic form. The results found are in agreement with those from CFT. Finally, we show that the proposed framework provides us with the elements needed for an independent LF study of exactly solvable models. We compute the non-perturbative correlation functions from the exact operator solution of the LF Thirring model and compare it to the analogous results in the SL theory. While the vacuum effects are automatically taken into account in the LF case, the non-trivial vacuum structure has to be incorported by an explicit diagonalization of the SL Hamiltonians, to obtain the equivalently complete solution.

  11. Broadband photocurrent enhancement and light-trapping in thin film Si solar cells with periodic Al nanoparticle arrays on the front.

    Science.gov (United States)

    Uhrenfeldt, C; Villesen, T F; Têtu, A; Johansen, B; Larsen, A Nylandsted

    2015-06-01

    Plasmonic resonances in metal nanoparticles are considered candidates for improved thin film Si photovoltaics. In periodic arrays the influence of collective modes can enhance the resonant properties of such arrays. We have investigated the use of periodic arrays of Al nanoparticles placed on the front of a thin film Si test solar cell. It is demonstrated that the resonances from the Al nanoparticle array causes a broadband photocurrent enhancement ranging from the ultraviolet to the infrared with respect to a reference cell. From the experimental results as well as from numerical simulations it is shown that this broadband enhancement is due to single particle resonances that give rise to light-trapping in the infrared spectral range and to collective resonances that ensure an efficient in-coupling of light in the ultraviolet-blue spectral range.

  12. Diagnostic system to measure spatial and temporal profiles of shock front using compact two-stage light-gas gun and line reflection method.

    Science.gov (United States)

    Yokoo, Manabu; Kawai, Nobuaki; Hironaka, Yoichiro; Nakamura, Kazutaka G; Kondo, Ken-Ichi

    2007-04-01

    A diagnostic system has been developed to obtain spatial and temporal profiles of shock front. A two-stage light-gas gun is used to accelerate impactors in velocity range with 4-9 km/s. The system consists of the Faraday-type electromagnetic sensors to measure impactor velocity, optical system with high-speed streak camera to measure shock-wave velocities, and the delay trigger system with self-adjustable pre-event pulse generator. We describe the specifications and performance of this system and data-analysis technique on the tilt and distortion of the shock front. Finally, we obtained the Hugoniot data of copper for system demonstration.

  13. A wide dynamic range BF{sub 3} neutron monitor with front-end electronics based on a logarithmic amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Ferrarini, M., E-mail: michele.ferrarini@polimi.i [Politecnico di Milano, Dipartimento Energia, via G. Ponzio 34/3, I-20133 Milano (Italy); Fondazione CNAO, via Caminadella 16, 20123 Milano (Italy); Varoli, V. [Politecnico di Milano, Dipartimento Energia, via G. Ponzio 34/3, I-20133 Milano (Italy); Favalli, A. [European Commission, Joint Research Centre, Institute for the Protection and Security of Citizen, TP 800, Via E. Fermi, 21027 Ispra (Vatican City State, Holy See) (Italy); Caresana, M. [Politecnico di Milano, Dipartimento Energia, via G. Ponzio 34/3, I-20133 Milano (Italy); Pedersen, B. [European Commission, Joint Research Centre, Institute for the Protection and Security of Citizen, TP 800, Via E. Fermi, 21027 Ispra (Italy)

    2010-02-01

    This paper describes a wide dynamic range neutron monitor based on a BF{sub 3} neutron detector. The detector is used in current mode, and front-end electronics based on a logarithmic amplifier are used in order to have a measurement capability ranging over many orders of magnitude. The system has been calibrated at the Polytechnic of Milan, CESNEF, with an AmBe neutron source, and has been tested in a pulsed field at the PUNITA facility at JRC, Ispra. The detector has achieved a dynamic range of over 6 orders of magnitude, being able to measure single neutron pulses and showing saturation-free response for a reaction rate up to 10{sup 6} s{sup -1}. It has also proved effective in measuring the PUNITA facility pulse integral fluence.

  14. New Insights into Color Confinement, Hadron Dynamics, Spectroscopy, and Jet Hadronization from Light-Front Holography and Superconformal Algebra

    Science.gov (United States)

    Brodsky, S. J.

    2017-07-01

    A fundamental problem in hadron physics is to obtain a relativistic color-confining, first approximation to QCD which can predict both hadron spectroscopy and the frame-independent light-front (LF) wavefunctions underlying hadron dynamics. The QCD Lagrangian with zero quark mass has no explicit mass scale; the classical theory is conformally invariant. Thus, a fundamental problem is to understand how the mass gap and ratios of masses - such as m ρ/ m p - can arise in chiral QCD. De Alfaro, Fubini, and Furlan have made an important observation that a mass scale can appear in the equations of motion without affecting the conformal invariance of the action if one adds a term to the Hamiltonian proportional to the dilatation operator or the special conformal operator and rescales the time variable. If one applies the same procedure to the light-front Hamiltonian, it leads uniquely to a confinement potential κ 4 ζ 2 for mesons, where ζ 2 is the LF radial variable conjugate to the q\\overline{q} invariant mass squared. The same result, including spin terms, is obtained using light-front holography - the duality between light-front dynamics and AdS5, the space of isometries of the conformal group if one modifies the action of AdS5 by the dilaton {e}^{κ^2}{z}^2 in the fifth dimension z . When one generalizes this procedure using superconformal algebra, the resulting light-front eigensolutions predict unified Regge spectroscopy of meson, baryon, and tetraquarks, including remarkable supersymmetric relations between the masses of mesons and baryons of the same parity. One also predicts observables such as hadron structure functions, transverse momentum distributions, and the distribution amplitudes defined from the hadronic light-front wavefunctions. The mass scale κ underlying confinement and hadron masses can be connected to the parameter {Λ}_{\\overline{MS}} in the QCD running coupling by matching the nonperturbative dynamics to the perturbative QCD regime. The

  15. Range image registration using a photometric metric under unknown lighting.

    Science.gov (United States)

    Thomas, Diego; Sugimoto, Akihiro

    2013-09-01

    Based on the spherical harmonics representation of image formation, we derive a new photometric metric for evaluating the correctness of a given rigid transformation aligning two overlapping range images captured under unknown, distant, and general illumination. We estimate the surrounding illumination and albedo values of points of the two range images from the point correspondences induced by the input transformation. We then synthesize the color of both range images using albedo values transferred using the point correspondences to compute the photometric reprojection error. This way allows us to accurately register two range images by finding the transformation that minimizes the photometric reprojection error. We also propose a practical method using the proposed photometric metric to register pairs of range images devoid of salient geometric features, captured under unknown lighting. Our method uses a hypothesize-and-test strategy to search for the transformation that minimizes our photometric metric. Transformation candidates are efficiently generated by employing the spherical representation of each range image. Experimental results using both synthetic and real data demonstrate the usefulness of the proposed metric.

  16. Fuel and stand characteristics in p. pine infested with mountain pine beetle, Ips beetle, and southwestern dwarf mistletoe in Colorado's Northern Front Range

    Science.gov (United States)

    Jennifer G. Klutsch; Russell D. Beam; William R. Jacobi; Jose F. Negron

    2008-01-01

    In the ponderosa pine forests of the northern Front Range of Colorado, downed woody debris amounts, fuel arrangement, and stand characteristics were assessed in areas infested with southwestern dwarf mistletoe (Arceuthobium vaginatum subsp. cryptopodum), mountain pine beetle (Dendroctonus ponderosae) and

  17. Entomological studies along the Colorado Front Range during a period of intense West Nile virus activity.

    Science.gov (United States)

    Bolling, B G; Moore, C G; Anderson, S L; Blair, C D; Beaty, B J

    2007-03-01

    To better understand the ecology of West Nile virus transmission in Northern Colorado, field studies were conducted in Larimer and Weld counties from September 2003 through March 2005. During summer studies, 18,540 adult mosquitoes were collected using light traps and gravid traps. West Nile virus RNA was detected in 24 of the 2,140 mosquito pools tested throughout the study area in 2003 and 2004. Culex tarsalis had the highest minimum infection rate (MIR) in both 2003 (MIR = 34.48) and in 2004 (MIR = 8.74). During winter studies, 9,391 adult mosquitoes were collected by aspirator from various overwintering sites including bridges and storm drains. The most frequently collected species was Culex pipiens. West Nile virus was not detected in our overwintering collections. The relationship between spring adult emergence and temperature inside and outside overwintering sites is described. Species composition of collections as well as the spatial and temporal distribution of West Nile virus detections are presented.

  18. Offshore wind profiling using light detection and ranging measurements

    DEFF Research Database (Denmark)

    Pena Diaz, Alfredo; Hasager, Charlotte Bay; Gryning, Sven-Erik

    2009-01-01

    The advantages and limitations of the ZephlR (R), a continuous-wave, focused light detection and ranging (LiDAR) wind profiler, to observe offshore winds and turbulence characteristics were tested during a 6 month campaign at the tronsformer/platform of Hams Rev, the world's largest wind form......-derived friction velocities and roughness lengths were compared to Charnock's sea roughness model. These overage values were found to be close to the model, although the scatter of the individual estimations of sea roughness length was large. Copyright (C) 2008 John Wiley & Sons, Ltd....

  19. Light Detection and Ranging (LIDAR) From Space - Laser Altimeters

    Science.gov (United States)

    Sun, Xiaoli

    2016-01-01

    Light detection and ranging, or lidar, is like radar but atoptical wavelengths. The principle of operation and theirapplications in remote sensing are similar. Lidars havemany advantages over radars in instrument designs andapplications because of the much shorter laser wavelengthsand narrower beams. The lidar transmitters and receiveroptics are much smaller than radar antenna dishes. Thespatial resolution of lidar measurement is much finer thanthat of radar because of the much smaller footprint size onground. Lidar measurements usually give a better temporalresolution because the laser pulses can be much narrowerthan radio frequency (RF) signals. The major limitation oflidar is the ability to penetrate clouds and ground surfaces.

  20. Discrete Symmetries on the Light Front and a General Relation connecting Nucleon Electric Dipole and Anomalous Magnetic Moments

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; Gardner, Susan; /Kentucky U.; Hwang, Dae Sung; /Sejong U.

    2006-01-11

    We consider the electric dipole form factor, F{sub 3}(q{sup 2}), as well as the Dirac and Pauli form factors, F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}), of the nucleon in the light-front formalism. We derive an exact formula for F{sub 3}(q{sup 2}) to complement those known for F{sub 1}(q{sup 2}) and F{sub 2}(q{sup 2}). We derive the light-front representation of the discrete symmetry transformations and show that time-reversal- and parity-odd effects are captured by phases in the light-front wave functions. We thus determine that the contributions to F{sub 2}(q{sup 2}) and F{sub 3}(q{sup 2}), Fock-state by Fock-state, are related, independent of the fundamental mechanism through which CP violation is generated. Our relation is not specific to the nucleon, but, rather, is true of spin-1/2 systems in general, be they lepton or baryon. The empirical values of the anomalous magnetic moments, in concert with empirical bounds on the associated electric dipole moments, can better constrain theories of CP violation. In particular, we find that the neutron and proton electric dipole moments echo the isospin structure of the anomalous magnetic moments, {kappa}{sup n} {approx} -{kappa}{sup p}.

  1. 2.5 Gbit/s Optical Receiver Front-End Circuit with High Sensitivity and Wide Dynamic Range

    Science.gov (United States)

    Zhu, Tiezhu; Mo, Taishan; Ye, Tianchun

    2017-12-01

    An optical receiver front-end circuit is designed for passive optical network and fabricated in a 0.18 um CMOS technology. The whole circuit consists of a transimpedance amplifier (TIA), a single-ended to differential amplifier and an output driver. The TIA employs a cascode stage as the input stage and auxiliary amplifier to reduce the miller effect. Current injecting technique is employed to enlarge the input transistor's transconductance, optimize the noise performance and overcome the lack of voltage headroom. To achieve a wide dynamic range, an automatic gain control circuit with self-adaptive function is proposed. Experiment results show an optical sensitivity of -28 dBm for a bit error rate of 10-10 at 2.5 Gbit/s and a maxim input optical power of 2 dBm using an external photodiode. The chip occupies an area of 1×0.9 mm2 and consumes around 30 mW from single 1.8 V supply. The front-end circuit can be used in various optical receivers.

  2. Rock Geochemistry and Mineralogy from Fault Zones and Polymetallic Fault Veins of the Central Front Range, Colorado

    Science.gov (United States)

    Caine, Jonathan S.; Bove, Dana J.

    2010-01-01

    During the 2004 to 2008 field seasons, approximately 200 hand samples of fault and polymetallic vein-related rocks were collected for geochemical and mineralogical analyses. The samples were collected by the U.S. Geological Survey as part of the Evolution of Brittle Structures Task under the Central Colorado Assessment Project (CCAP) of the Mineral Resources Program (http://minerals.cr.usgs.gov/projects/colorado_assessment/index.html). The purpose of this work has been to characterize the relation between epithermal, polymetallic mineral deposits, paleostress, and the geological structures that hosted fluid flow and localization of the deposits. The data in this report will be used to document and better understand the processes that control epithermal mineral-deposit formation by attempting to relate the geochemistry of the primary structures that hosted hydrothermal fluid flow to their heat and fluid sources. This includes processes from the scale of the structures themselves to the far field scale, inclusive of the intrusive bodies that have been thought to be the sources for the hydrothermal fluid flow. The data presented in this report are part of a larger assessment effort on public lands. The larger study area spans the region of the southern Rocky Mountains in Colorado from the Wyoming to New Mexico borders and from the eastern boundary of the Front Range to approximately the longitude of Vail and Leadville, Colorado. Although the study area has had an extensive history of geological mapping, the mapping has resulted in a number of hypotheses that are still in their infancy of being tested. For example, the proximity of polymetallic veins to intrusive bodies has been thought to reflect a genetic relation between the two features; however, this idea has not been well tested with geochemical indicators. Recent knowledge regarding the coupled nature of stress, strain, fluid flow, and geochemistry warrant new investigations and approaches to test a variety of

  3. The Relative Importance of HNO3 and RONO2 as NOX Sinks in the Colorado Front Range

    Science.gov (United States)

    Sparks, T.; Ebben, C. J.; Wooldridge, P. J.; Cohen, R. C.

    2016-12-01

    NOX (NO + NO2) is a regulated pollutant, primarily emitted from combustion processes, that contributes to the formation of ground level ozone. The lifetime of NOX in the atmosphere, and therefore its contribution to ozone production, is controlled by the loss of NOX to various sinks, primarily HNO3 and RONO2. As NOX concentrations in urban areas decrease due to regulation, the relative importance of these NOX sinks shifts from HNO3 being the dominant sink to RONO2 becoming more significant. Using measurements from the DISCOVER-AQ and FRAPPE campaigns from the summer of 2014, we examine the relative importance of HNO3 and RONO2 as NOX sinks and their relation to NOX concentration in the Colorado Front Range.

  4. Climate Drives Episodic Conifer Establishment after Fire in Dry Ponderosa Pine Forests of the Colorado Front Range, USA

    Directory of Open Access Journals (Sweden)

    Monica T. Rother

    2017-05-01

    Full Text Available In recent years, warming climate and increased fire activity have raised concern about post-fire recovery of western U.S. forests. We assessed relationships between climate variability and tree establishment after fire in dry ponderosa pine forests of the Colorado Front Range. We harvested and aged over 400 post-fire juvenile ponderosa pine (Pinus ponderosa and Douglas-fir (Pseudotsuga menziesii trees using an improved tree-ring based approach that yielded annually-resolved dates and then assessed relationships between climate variability and pulses of tree establishment. We found that tree establishment was largely concentrated in years of above-average moisture availability in the growing season, including higher amounts of precipitation and more positive values of the Palmer Drought Severity Index. Under continued climate change, drier conditions associated with warming temperatures may limit forest recovery after fire, which could result in lower stand densities or shifts to non-forested vegetation in some areas.

  5. Links between N deposition and nitrate export from a high-elevation watershed in the Colorado Front Range

    Science.gov (United States)

    Mast, M. Alisa; Clow, David W.; Baron, Jill S.; Wetherbee, Gregory A.

    2014-01-01

    Long-term patterns of stream nitrate export and atmospheric N deposition were evaluated over three decades in Loch Vale, a high-elevation watershed in the Colorado Front Range. Stream nitrate concentrations increased in the early 1990s, peaked in the mid-2000s, and have since declined by over 40%, coincident with trends in nitrogen oxide emissions over the past decade. Similarities in the timing and magnitude of N deposition provide evidence that stream chemistry is responding to changes in atmospheric deposition. The response to deposition was complicated by a drought in the early 2000s that enhanced N export for several years. Other possible explanations, including forest disturbance, snow depth, or permafrost melting, could not explain patterns in N export. Our results show that stream chemistry responds rapidly to changes in N deposition in high-elevation watersheds, similar to the response observed to changes in sulfur deposition.

  6. Crash compatibility between cars and light trucks: benefits of lowering front-end energy-absorbing structure in SUVs and pickups.

    Science.gov (United States)

    Baker, Bryan C; Nolan, Joseph M; O'Neill, Brian; Genetos, Alexander P

    2008-01-01

    Passenger vehicles are designed to absorb crash energy in frontal crashes through deformation or crush of energy-absorbing structures forward of the occupant compartment. In collisions between cars and light trucks (i.e., pickups and SUVs), however, the capacity of energy-absorption structures may not be fully utilized because mismatches often exist between the heights of these structures in the colliding vehicles. In 2003 automakers voluntarily committed to new design standards aimed at reducing the height mismatches between cars and light trucks. By September 2009 all new light trucks will have either the primary front structure (typically the frame rails) or a secondary structure connected to the primary structure low enough to interact with the primary structures in cars, which for most cars is about the height of the front bumper. To estimate the overall benefit of the voluntary commitment, the real-world crash experience of light trucks already meeting the height-matching criteria was compared with that of light trucks not meeting the criteria for 2000-2003 model light trucks in collisions with passenger cars during calendar years 2001-2004. The estimated benefits of lower front energy-absorbing structure were a 19 percent reduction (pcar drivers in front-to-front crashes with light trucks and a 19 percent reduction (pcar drivers in front-to-driver-side crashes with light trucks.

  7. Imaging X-ray detector front-end with high dynamic range: IDeF-X HD

    Science.gov (United States)

    Gevin, O.; Lemaire, O.; Lugiez, F.; Michalowska, A.; Baron, P.; Limousin, O.; Delagnes, E.

    2012-12-01

    Presented circuit, IDeF-X HD (Imaging Detector Front-end) is a member of the IDeF-X ASICs family for space applications. It has been optimized for a half millimeter pitch CdTe or CdZnTe pixelated detector arranged in 16×16 array. It is aimed to operate in the hard X-ray range from few keV up to 250 keV or more. The ASIC has been realized in AMS 0.35 μm CMOS process. The IDeF-X HD is a 32 channel analog front-end with self-triggering capability. The architecture of the analog channel includes a chain of charge sensitive amplifier with continuous reset system and non-stationary noise suppressor, adjustable gain stage, pole-zero cancellation stage, adjustable shaping time low pass filter, baseline holder and peak detector with discriminator. The power consumption of the IDeF-X HD is 800 μW per channel. With the in-channel variable gain stage the nominal 250 keV dynamic range of the ASIC can be extended up to 1 MeV anticipating future applications using thick sensors. Measuring the noise performance without a detector at the input with minimized leakage current (programmable) at the input, we achieved ENC of 33 electrons rms at 10.7 μs peak time. Measurements with CdTe detector show good energy resolution FWHM of 1.1 keV at 60 keV and 4.3 keV at 662 keV with detection threshold below 4 keV. In addition, an absolute temperature sensor has been integrated with resolution of 1.5 °C.

  8. The effect of entrainment through atmospheric boundary layer growth on observed and modeled surface ozone in the Colorado Front Range

    Science.gov (United States)

    Kaser, L.; Patton, E. G.; Pfister, G. G.; Weinheimer, A. J.; Montzka, D. D.; Flocke, F.; Thompson, A. M.; Stauffer, R. M.; Halliday, H. S.

    2017-06-01

    Ozone concentrations at the Earth's surface are controlled by meteorological and chemical processes and are a function of advection, entrainment, deposition, and net chemical production/loss. The relative contributions of these processes vary in time and space. Understanding the relative importance of these processes controlling surface ozone concentrations is an essential component for designing effective regulatory strategies. Here we focus on the diurnal cycle of entrainment through atmospheric boundary layer (ABL) growth in the Colorado Front Range. Aircraft soundings and surface observations collected in July/August 2014 during the DISCOVER-AQ/FRAPPÉ (Deriving Information on Surface conditions from Column and Vertically Resolved Observations Relevant to Air Quality/Front Range Air Pollution and Photochemistry Éxperiment) campaigns and equivalent data simulated by a regional chemical transport model are analyzed. Entrainment through ABL growth is most important in the early morning, fumigating the surface at a rate of 5 ppbv/h. The fumigation effect weakens near noon and changes sign to become a small dilution effect in the afternoon on the order of -1 ppbv/h. The chemical transport model WRF-Chem (Weather Research and Forecasting Model with chemistry) underestimates ozone at all altitudes during this study on the order of 10-15 ppbv. The entrainment through ABL growth is overestimated by the model in the order of 0.6-0.8 ppbv/h. This results from differences in boundary layer growth in the morning and ozone concentration jump across the ABL top in the afternoon. This implicates stronger modeled fumigation in the morning and weaker modeled dilution after 11:00 LT.

  9. Elevation-Dependent Temperature Trends in the Rocky Mountain Front Range: Changes over a 56- and 20-Year Record

    Science.gov (United States)

    McGuire, Chris R.; Nufio, César R.; Bowers, M. Deane; Guralnick, Robert P.

    2012-01-01

    Determining the magnitude of climate change patterns across elevational gradients is essential for an improved understanding of broader climate change patterns and for predicting hydrologic and ecosystem changes. We present temperature trends from five long-term weather stations along a 2077-meter elevational transect in the Rocky Mountain Front Range of Colorado, USA. These trends were measured over two time periods: a full 56-year record (1953–2008) and a shorter 20-year (1989–2008) record representing a period of widely reported accelerating change. The rate of change of biological indicators, season length and accumulated growing-degree days, were also measured over the 56 and 20-year records. Finally, we compared how well interpolated Parameter-elevation Regression on Independent Slopes Model (PRISM) datasets match the quality controlled and weather data from each station. Our results show that warming signals were strongest at mid-elevations over both temporal scales. Over the 56-year record, most sites show warming occurring largely through increases in maximum temperatures, while the 20-year record documents warming associated with increases in maximum temperatures at lower elevations and increases in minimum temperatures at higher elevations. Recent decades have also shown a shift from warming during springtime to warming in July and November. Warming along the gradient has contributed to increases in growing-degree days, although to differing degrees, over both temporal scales. However, the length of the growing season has remained unchanged. Finally, the actual and the PRISM interpolated yearly rates rarely showed strong correlations and suggest different warming and cooling trends at most sites. Interpretation of climate trends and their seasonal biases in the Rocky Mountain Front Range are dependent on both elevation and the temporal scale of analysis. Given mismatches between interpolated data and the directly measured station data, we caution

  10. Elevation-dependent temperature trends in the Rocky Mountain Front Range: changes over a 56- and 20-year record.

    Directory of Open Access Journals (Sweden)

    Chris R McGuire

    Full Text Available Determining the magnitude of climate change patterns across elevational gradients is essential for an improved understanding of broader climate change patterns and for predicting hydrologic and ecosystem changes. We present temperature trends from five long-term weather stations along a 2077-meter elevational transect in the Rocky Mountain Front Range of Colorado, USA. These trends were measured over two time periods: a full 56-year record (1953-2008 and a shorter 20-year (1989-2008 record representing a period of widely reported accelerating change. The rate of change of biological indicators, season length and accumulated growing-degree days, were also measured over the 56 and 20-year records. Finally, we compared how well interpolated Parameter-elevation Regression on Independent Slopes Model (PRISM datasets match the quality controlled and weather data from each station. Our results show that warming signals were strongest at mid-elevations over both temporal scales. Over the 56-year record, most sites show warming occurring largely through increases in maximum temperatures, while the 20-year record documents warming associated with increases in maximum temperatures at lower elevations and increases in minimum temperatures at higher elevations. Recent decades have also shown a shift from warming during springtime to warming in July and November. Warming along the gradient has contributed to increases in growing-degree days, although to differing degrees, over both temporal scales. However, the length of the growing season has remained unchanged. Finally, the actual and the PRISM interpolated yearly rates rarely showed strong correlations and suggest different warming and cooling trends at most sites. Interpretation of climate trends and their seasonal biases in the Rocky Mountain Front Range are dependent on both elevation and the temporal scale of analysis. Given mismatches between interpolated data and the directly measured station data

  11. Spatial Variability in Ozone and CO2 Flux during the Front Range Air Pollution and Photochemistry Experiment

    Science.gov (United States)

    Almand-Hunter, B.; Piedrahita, R.; Kaushik, A.; Noone, D. C.; Walker, J. T.; Hannigan, M.

    2014-12-01

    Air quality problems persist in the Northern Front-Range Metropolitan Area (NFRMA) of Colorado despite efforts to reduce emissions, and summertime ozone concentrations frequently exceed the NAAQS. Atmospheric modeling in the NFRMA is challenging due to the complex topography of the area, as well as diversity of pollutant sources (urban NOx and VOCs, power plants, oil and gas, agricultural emissions, biogenic emissions, and wildfires). An improved understanding of the local atmospheric chemistry will enable researchers to advance atmospheric models, which will subsequently be used to develop and test more effective air quality management strategies. The Front Range Air Pollution and Photochemistry Experiment (FRAPPE) investigates this problem through detailed examination of atmospheric chemistry in the NFRMA. Our project specifically explores the spatial variability in ozone (O3) concentration and dry deposition within the FRAPPE study area. One source of uncertainty in atmospheric models is O3 flux, which varies spatially due to local meteorology and variation in ambient concentration and deposition velocity. Model grid cells typically range in size from 10-100 km and 100-500 km, for regional and global models, respectively, and accurate representations of an entire grid cell cannot always be achieved. Large spatial variability within a model grid cell can lead to poor estimates of trace-gas flux and concentration. Our research addresses this issue by measuring spatial variability in O3 flux using low-cost dry-deposition flux chambers. We are measuring O3 and CO2 flux with 5 low-cost flux chambers and one eddy-covariance tower. The eddy-covariance tower is located at the Boulder Atmospheric Observatory in Erie, CO. All 5 chambers are within a 8.3 x 6 km square, with one chamber collocated with the eddy-covariance tower, and the other 4 chambers at distances of 0.33, 1.14, 3.22, and 7.55 km from the tower. The largest distance between any two chambers is 8.5 km. All

  12. Douglas-Fir Tussock Moth- and Douglas-Fir Beetle-Caused Mortality in a Ponderosa Pine/Douglas-Fir Forest in the Colorado Front Range, USA

    Directory of Open Access Journals (Sweden)

    José F. Negrón

    2014-12-01

    Full Text Available An outbreak of the Douglas-fir tussock moth, Orgyia pseudotsugata McDunnough, occurred in the South Platte River drainage on the Pike-San Isabel National Forest in the Colorado Front Range attacking Douglas-fir, Pseudotsuga menziesii (Mirb. Franco. Stocking levels, species composition, and tree size in heavily and lightly defoliated stands were similar. Douglas-fir tussock moth defoliation resulted in significant Douglas-fir mortality in the heavily defoliated stands, leading to a change in dominance to ponderosa pine, Pinus ponderosa Lawson. Douglas-fir beetle, Dendroctonus pseudotsuqae Hopkins, populations increased following the defoliation event but caused less mortality, and did not differ between heavily and lightly defoliated stands. Douglas-fir tussock moth-related mortality was greatest in trees less than 15 cm dbh (diameter at 1.4 m above the ground that grew in suppressed and intermediate canopy positions. Douglas-fir beetle-related mortality was greatest in trees larger than 15 cm dbh that grew in the dominant and co-dominant crown positions. Although both insects utilize Douglas-fir as its primary host, stand response to infestation is different. The extensive outbreak of the Douglas-fir tussock moth followed by Douglas-fir beetle activity may be associated with a legacy of increased host type growing in overstocked conditions as a result of fire exclusion.

  13. Health evaluation of free-ranging and captive blue-fronted Amazon parrots (Amazona aestiva) in the Gran chaco, Bolivia.

    Science.gov (United States)

    Deem, Sharon L; Noss, Andrew J; Cuéllar, Rosa Leny; Karesh, William B

    2005-12-01

    Bolivia has a total of 47 species of Psittacidae, seven of which have been identified in our study site, the semiarid Gran Chaco of the Isoso. One species, the blue-fronted parrot (Amazona aestiva), is frequently captured by local Isoseño Guaraní Indians for exploitation on the national and international market. These birds are often temporarily housed in small villages under unhygienic conditions with poultry and other domestic species. On occasion, these parrots escape back to the wild. Additionally, many of these birds are kept as pets or are used to lure wild. parrots within slingshot range for subsequent capture. In this study, we evaluated the health status, including the level of exposure to selected infectious agents, in the wild-caught captive birds and free-ranging birds. Physical examinations were performed, and blood was collected, from 54 live birds (20 captive and 34 free-ranging). Feces were collected from 15 birds (seven captive and eight free-ranging). Necropsies were also performed on four recently dead wild-caught birds. On serologic testing, no birds were found to have antibodies to avian influenza virus, Chlamydophila psittaci, infectious bronchitis virus, infectious bursal disease virus, infectious laryngotracheitis virus, Marek's disease virus, paramyxovirus-1, paramyxovirus-2, paramyxovirus-3, polyomavirus, eastern equine encephalitis virus, western equine encephalitis virus, or Venezuelan equine encephalitis virus. Positive antibody titers were found for psittacine herpesvirus (8/44, 18.2%), Aspergillus spp. (3/51, 5.9%), and Salmonella pullorum (33/49, 67.3%). All three of the birds that tested antibody positive for Aspergillus spp. were captive, whereas six of the eight and 15 of the 33 birds that tested positive for psittacine herpesvirus and S. pullorum, respectively, were wild.

  14. Investigations into light-front interactions for massless fields (I): non-constructibility of higher spin quartic amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Bengtsson, Anders K.H. [Academy of Textiles, Engineering and Economics, University of Borås,Allégatan 1, SE-50190 Borås (Sweden)

    2016-12-27

    The dynamical commutators of the light-front Poincaré algebra yield first order differential equations in the p{sup +} momenta for the interaction vertex operators. The homogeneous solution to the equation for the quartic vertex is studied. Consequences as regards the constructibility assumption of quartic higher spin amplitudes from cubic amplitudes are discussed. The existence of quartic contact interactions unrelated to cubic interactions by Poincaré symmetry indicates that the higher spin S-matrix is not constructible. Thus quartic amplitude based no-go results derived by BCFW recursion for Minkowski higher spin massless fields may be circumvented.

  15. Light Cone 2016 : Challenges for Theory and Experiment in Hadron and Nuclear Physics on the Light Front

    CERN Document Server

    Pena, Teresa

    2018-01-01

    The Light-Cone 2016 conference, held in September 2016 in Lisbon, Portugal, belongs to a series of yearly Light-Cone meetings that started in 1991. As its predecessors, this conference was guided by the objectives defined by the International Light Cone Advisory Committee, namely to “advance research in quantum field theory, particularly light-cone quantization methods applicable to the solution of physical problems”. This volume compiles selected papers presented at the conference by experts from all over the world, which describe recent progress in theoretical research, and new results and planned activities at leading experimental facilities, with special emphasis on the physics of hadrons and nuclei.

  16. Analog Circuit Design Low Voltage Low Power; Short Range Wireless Front-Ends; Power Management and DC-DC

    CERN Document Server

    Roermund, Arthur; Baschirotto, Andrea

    2012-01-01

    The book contains the contribution of 18 tutorials of the 20th workshop on Advances in Analog Circuit Design.  Each part discusses a specific to-date topic on new and valuable design ideas in the area of analog circuit design. Each part is presented by six experts in that field and state of the art information is shared and overviewed. This book is number 20 in this successful series of Analog Circuit Design, providing valuable information and excellent overviews of Low-Voltage Low-Power Data Converters - Chaired by Prof. Anderea Baschirotto, University of Milan-Bicocca Short Range Wireless Front-Ends - Chaired by Prof. Arthur van Roermund, Eindhoven University of Technology Power management and DC-DC - Chaired by Prof. M. Steyaert, Katholieke University Leuven Analog Circuit Design is an essential reference source for analog circuit designers and researchers wishing to keep abreast with the latest development in the field. The tutorial coverage also makes it suitable for use in an advanced design.

  17. Source characterization of volatile organic compounds in the Colorado Northern Front Range Metropolitan Area during spring and summer 2015

    Science.gov (United States)

    Abeleira, A.; Pollack, I. B.; Sive, B.; Zhou, Y.; Fischer, E. V.; Farmer, D. K.

    2017-03-01

    Hourly measurements of 46 volatile organic compounds (VOCs) from the Boulder Atmospheric Observatory in Erie, CO, were collected over 16 weeks in spring and summer 2015. Average VOC reactivity (1.2 s-1 in spring and 2.4 s-1 in summer) was lower than most other U.S. urban sites. Positive matrix factorization analysis identified five VOC factors in the spring, corresponding to sources from (1) long-lived oil and natural gas (ONG-long lived), (2) short-lived oil and natural gas (ONG-short lived), (3) traffic, (4) background, and (5) secondary chemical production. In the summer, an additional biogenic factor was dominated by isoprene. While ONG-related VOCs were the single largest contributor (40-60%) to the calculated VOC reactivity with hydroxyl radicals (OH) throughout the morning in both spring and summer, the biogenic factor substantially enhanced afternoon and evening (2-10 P.M. local time) VOC reactivity (average of 21%; maxima of 49% of VOC reactivity) during summertime. These results contrast with a previous summer 2012 campaign which showed that biogenics contributed only 8% of VOC reactivity on average. The interannual differences suggest that the role of biogenic VOCs in the Colorado Northern Front Range Metropolitan Area (NFRMA) varies with environmental conditions such as drought stress. Overall, the NFRMA was more strongly influenced by ONG sources of VOCs than other urban and suburban regions in the U.S.

  18. The influence of vegetation cover on debris-flow density during an extreme rainfall in the northern Colorado Front Range

    Science.gov (United States)

    Rengers, Francis; McGuire, Luke; Coe, Jeffrey A.; Kean, Jason W.; Baum, Rex L.; Staley, Dennis M.; Godt, Jonathan W.

    2016-01-01

    We explored regional influences on debris-flow initiation throughout the Colorado Front Range (Colorado, USA) by exploiting a unique data set of more than 1100 debris flows that initiated during a 5 day rainstorm in 2013. Using geospatial data, we examined the influence of rain, hillslope angle, hillslope aspect, and vegetation density on debris-flow initiation. In particular we used a greenness index to differentiate areas of high tree density from grass and bare soil. The data demonstrated an overwhelming propensity for debris-flow initiation on south-facing hillslopes. However, when the debris-flow density was analyzed with respect to total rainfall and greenness we found that most debris flows occurred in areas of high rainfall and low tree density, regardless of hillslope aspect. These results indicate that present-day tree density exerts a stronger influence on debris-flow initiation locations than aspect-driven variations in soil and bedrock properties that developed over longer time scales.

  19. Long-Range Emergency Preemption of Traffic Lights

    Science.gov (United States)

    Bachelder, Aaron

    2005-01-01

    A forwarding system could prove beneficial as an addition to an electronic communication-and-control system that automatically modifies the switching of traffic lights to give priority to emergency vehicles. A system to which the forwarding system could be added could be any of a variety of emergency traffic-signal-preemption systems: these include systems now used in some municipalities as well as advanced developmental systems described in several NASA Tech Briefs articles in recent years. Because of a variety of physical and design limitations, emergency traffic-signal- preemption systems now in use are often limited in range to only one intersection at a time: in a typical system, only the next, closest intersection is preempted for an emergency vehicle. Simulations of gridlock have shown that such systems offer minimal advantages and can even cause additional delays. In analogy to what happens in fluid dynamics, the forwarding system insures that flow at a given location is sustained by guaranteeing downstream flow along the predicted route (typically a main artery) and intersecting routes (typically, side streets). In simplest terms, the forwarding system starts by taking note of any preemption issued by the preemption system to which it has been added. The forwarding system predicts which other intersections could be encountered by the emergency vehicle downstream of the newly preempted intersection. The system then forwards preemption triggers to those intersections. Beyond affording a right of way for the emergency vehicle at every intersection that lies ahead along any likely route from the current position of the vehicle, the forwarding system also affords the benefit of clearing congested roads far ahead of the vehicle. In a metropolitan environment with heavy road traffic, forwarding of preemption triggers could greatly enhance the performance of a pre-existing preemption system.

  20. Geometric design of a multisensor structured light range digitizer

    Science.gov (United States)

    Commean, Paul K.; Smith, Kirk E.; Bhatia, Gulab H.; Vannier, Michael W.

    1994-04-01

    An optical noncontact 3-D range digitizer based on projection of 2-D structured light patterns and multiplexed charge injection device (CID) camera sensors has been developed. The system acquires digitized data in 0.75 s and allows 360-deg examination of the subject's head and facial surface features in less than 1 s, making it suitable for digitizing children as well as adults. The resultant 3-D surface data is suitable for computer graphics display and manipulation, numerically controlled replication, and further processing such as surface measurement extraction. The digitizer uses a set of six stationary sensors positioned about the subject. A sensor consists of a pattern projector and a solid state video camera. This device allows quantitative volume measurements and employs no harmful ionizing radiation. The cost of a scan with this technology is substantially less than that of alternative means of collecting 3-D surface data sets, such as by stereometric, moiré fringe, and single-point digitization. This system was geometrically designed such that any surface of the head or facial area was independently digitized by a minimum of two sensors and to capture areas normally occluded with other techniques. The dimensions of the structure were derived to satisfy physical constraints placed on its overall size. The camera and projector orientations in space, the distance from the lens centers to the center of the digitizing volume, and the lens focal lengths were determined analytically. To reduce cost, a standard lens nearest the analytical value was used. Based on the standard size lens, the field of view was calculated.

  1. Cervical range of motion, cervical and shoulder strength in senior versus age-grade Rugby Union International front-row forwards.

    Science.gov (United States)

    Davies, Mark; Moore, Isabel S; Moran, Patrick; Mathema, Prabhat; Ranson, Craig A

    2016-05-01

    To provide normative values for cervical range of motion (CROM), isometric cervical and shoulder strength for; International Senior professional, and International Age-grade Rugby Union front-row forwards. Cross-sectional population study. All international level front-row players within a Rugby Union Tier 1 Nation. Nineteen Senior and 21 Age-grade front-row forwards underwent CROM, cervical and shoulder strength testing. CROM was measured using the CROM device and the Gatherer System was used to measure multi-directional isometric cervical and shoulder strength. The Age-grade players had significantly lower; cervical strength (26-57% deficits), cervical flexion to extension strength ratios (0.5 vs. 0.6), and shoulder strength (2-36% deficits) than the Senior players. However, there were no differences between front-row positions within each age group. Additionally, there were no differences between age groups or front-row positions in the CROM measurements. Senior Rugby Union front-row forwards have greater cervical and shoulder strength than Age-grade players, with the biggest differences being in cervical strength, highlighting the need for age specific normative values. Importantly, Age-grade players should be evaluated to ensure they have developed sufficient cervical strength prior to entering professional level Rugby Union. Copyright © 2015 Elsevier Ltd. All rights reserved.

  2. Engineering the phase front of light with phase-change material based planar lenses.

    Science.gov (United States)

    Chen, Yiguo; Li, Xiong; Sonnefraud, Yannick; Fernández-Domínguez, Antonio I; Luo, Xiangang; Hong, Minghui; Maier, Stefan A

    2015-03-02

    A novel hybrid planar lens is proposed to engineer the far-field focusing patterns. It consists of an array of slits which are filled with phase-change material Ge2Sb2Te5 (GST). By varying the crystallization level of GST from 0% to 90%, the Fabry-Pérot resonance supported inside each slit can be spectrally shifted across the working wavelength at 1.55 µm, which results in a transmitted electromagnetic phase modulation as large as 0.56π. Based on this geometrically fixed platform, different phase fronts can be constructed spatially on the lens plane by assigning the designed GST crystallization levels to the corresponding slits, achieving various far-field focusing patterns. The present work offers a promising route to realize tunable nanophotonic components, which can be used in optical circuits and imaging applications.

  3. ;Inverted; zircon and apatite (U-Th)/He dates from the Front Range, Colorado: High-damage zircon as a low-temperature (<50 °C) thermochronometer

    Science.gov (United States)

    Johnson, Joshua E.; Flowers, Rebecca M.; Baird, Graham B.; Mahan, Kevin H.

    2017-05-01

    Zircon (U-Th)/He (ZHe) data were acquired for 23 Proterozoic basement samples from an E-W transect through the Colorado Front Range to evaluate whether metamict zircons yield sensible (U-Th)/He data patterns and useful thermal history information. The 112 ZHe dates vary from 147 to 7 Ma, define positive and negative date-eU correlations, and are younger than titanite (U-Th)/He dates that range from 976 to 614 Ma. At moderate to high alpha dose of 1018-1019 α /g, zircons from the range core yield Laramide (52.5 ± 9.6 Ma) dates, whereas those within ∼15 km of the range front yield Miocene (21.6 ± 7.7 Ma) results. The He dates for the high alpha dose zircons are reproducible within each sample suite despite their visibly metamict character. The ∼20 Ma range front ZHe dates are younger than apatite (U-Th)/He (AHe) dates (66.5 ± 9.6 Ma) and published apatite fission-track data (65-45 Ma) for the same and nearby samples. Thermal history simulations can reproduce the first-order range front date-eU patterns and ZHe-AHe date inversion, but the high-damage zircons are more He retentive than predicted by the zircon damage He kinetic model. The ∼20 Ma ZHe dates may be explained by reheating from hydrothermal fluids along range front faults. The results demonstrate the promise of using He data for high-damage zircons to detect low-temperature (<50 °C) events within and below the temperature sensitivity of the AHe system.

  4. VOC Measurements in the Northern Colorado Front Range Metropolitan Area: Investigating the Impact of Oil and Natural Gas Emissions on O3 Production

    Science.gov (United States)

    Abeleira, A.; Farmer, D.; Fischer, E. V.; Pollack, I. B.; Zaragoza, J.

    2015-12-01

    Authors: Ilana Pollock1,2, Jake Zaragoza2, Emily V. Fischer2, Delphine K. Farmer11. Department of Chemistry, Colorado State University, Fort Collins, CO 2. Department of Atmospheric Science, Colorado State University, Fort Collins, CO During summer months, the Northern Front Range Metropolitan Area (NFRMA) of Colorado consistently violates the 75 ppbv 8-hour EPA National Ambient Air Quality Standard (NAAQS) for ambient ozone (O3), despite continued reduction in anthropogenic emissions. The region has been deemed an O3 non-attainment zone since 2008. Ground-level O3 is produced from photochemical catalytic cycles involving OH radicals, volatile organic compounds (VOCs), and NOx (NO + NO2). VOC emissions in the NFRMA are dominated by anthropogenic sources and influenced by biogenic and agricultural sources, while NOx emissions are mainly from automobile exhaust. A growing concern in the region is the role of oil and natural gas (ONG) on VOC concentrations and the potential for O3 production. Increases in local VOC emissions will likely cause subsequent increase in local O3 concentrations as PO3 increases in a region that is already affected by high O3episodes. As a part of the SONGNEX 2015 (Shale Oil and Natural Gas Nexus) campaign, we measured a broad suite of speciated VOCs during two 8-week deployments (March-May 2015, July-September 2015) at the Boulder Atmospheric Observatory in Erie, CO. VOC measurements were made with a custom-online multichannel gas chromatography system (50+ compounds hourly), along with measurements of O3, SO2, NOx, NOy, PAN, CO, CO2, and CH4. We use these data to investigate the role of different VOC sources, and ONG in particular, in contributing to VOC reactivity and thus instantaneous O3 production. Preliminary analysis of the Spring VOC data indicates that VOC reactivity is dominated by light alkanes typical of ONG emissions - specifically propane, consistent with previous winter-time studies. We will use the observed temperature

  5. Impact of front-of-pack 'traffic-light' nutrition labelling on consumer food purchases in the UK.

    Science.gov (United States)

    Sacks, Gary; Rayner, Mike; Swinburn, Boyd

    2009-12-01

    Front-of-pack 'traffic-light' nutrition labelling has been widely proposed as a tool to improve public health nutrition. This study examined changes to consumer food purchases after the introduction of traffic-light labels with the aim of assessing the impact of the labels on the 'healthiness' of foods purchased. The study examined sales data from a major UK retailer in 2007. We analysed products in two categories ('ready meals' and sandwiches), investigating the percentage change in sales 4 weeks before and after traffic-light labels were introduced, and taking into account seasonality, product promotions and product life-cycle. We investigated whether changes in sales were related to the healthiness of products. All products that were not new and not on promotion immediately before or after the introduction of traffic-light labels were selected for the analysis (n = 6 for ready meals and n = 12 for sandwiches). For the selected ready-meals, sales increased (by 2.4% of category sales) in the 4 weeks after the introduction of traffic-light labels, whereas sales of the selected sandwiches did not change significantly. Critically, there was no association between changes in product sales and the healthiness of the products. This short-term study based on a small number of ready meals and sandwiches found that the introduction of a system of four traffic-light labels had no discernable effect on the relative healthiness of consumer purchases. Further research on the influence of nutrition signposting will be needed before this labelling format can be considered a promising public health intervention.

  6. Structural and Geomorphic Controls in Altitudinal Treeline: a Case Study in the Front Ranges of the Canadian Rocky Mountains

    Science.gov (United States)

    Macias Fauria, M.; Johnson, E. A.

    2009-12-01

    Altitudinal treelines occur on mountain slopes. The geological history of mountain systems sets both the distribution of slope angles, aspects and lengths, and the physical characteristics of the bedrock and regolith on which trees have to establish and grow. We show that altitudinal treeline is largely controlled at an ecosystem level by structural and slope (i.e. gravitational) geomorphic processes operating at a range of temporal and spatial scales, which have direct influence on the hydrological properties of the substrate (affecting the trees’ water and energy budget), as well as on substrate stability, both of which affect recruitment and growth of trees. The study was conducted over a relatively large area of > 200 km2 in the Front Ranges of the Canadian Rocky Mountains, selected to contain the regional diversity of slopes and substrates, which is the result of hundreds of millions of years of sea deposition, subsequent mountain building, and deep erosion by glaciations. Very high-resolution remote sensing data (LiDAR), aerial orthophotos taken at several times since the late 1940s, and ground truthing were employed to classify the terrain into process-based geomorphic units. High resolution, landscape-scale treeline studies are able avoid potential biases in site selection (i.e. selection of sites that are not representative of the overall regional treeline), and consequently capture the coupling between trees and the environment at an ecosystem (regional) level. Moreover, explicitly accounting for slope and substrate-related processes occurring in the studied mountain region is paramount in order to understand the dynamics of trees at their altitudinal distribution limit. Presence of trees in each unit was found to be controlled by a set of parameters relevant to both hydrological and slope processes, such as contributing area, slope angle, regolith transmissivity, and aspect. Our results show no treeline advance over the last 60 years in the region, as

  7. Generalized parton distributions and transverse densities in a light-front quark-diquark model for the nucleons

    Energy Technology Data Exchange (ETDEWEB)

    Mondal, Chandan; Chakrabarti, Dipankar [Indian Institute of Technology Kanpur, Department of Physics, Kanpur (India)

    2015-06-15

    We present a study of the generalized parton distributions (GPDs) for the quarks in a proton in both momentum and position spaces using the light-front wave functions (LFWFs) of a quark-diquark model for the nucleon predicted by the soft-wall model of AdS/QCD. The results are compared with the soft-wall AdS/QCD model of proton GPDs for zero skewness. We also calculate the GPDs for nonzero skewness. We observe that the GPDs have a diffraction pattern in longitudinal position space, as seen before in other models. Then we present a comparative study of the nucleon charge and anomalous magnetization densities in the transverse plane. Flavor decompositions of the form factors and transverse densities are also discussed. (orig.)

  8. Branching fractions of semileptonic D and D_s decays from the covariant light-front quark model

    Science.gov (United States)

    Cheng, Hai-Yang; Kang, Xian-Wei

    2017-09-01

    Based on the predictions of the relevant form factors from the covariant light-front quark model, we show the branching fractions for the D (D_s) → (P, S, V, A) ℓ ν _ℓ (ℓ =e or μ ) decays, where P denotes the pseudoscalar meson, S the scalar meson with a mass above 1 GeV, V the vector meson and A the axial-vector one. Comparison with the available experimental results are made, and we find an excellent agreement. The predictions for other decay modes can be tested in a charm factory, e.g., the BESIII detector. The future measurements will definitely further enrich our knowledge of the hadronic transition form factors as well as the inner structure of the even-parity mesons ( S and A).

  9. Branching fractions of semileptonic D and D{sub s} decays from the covariant light-front quark model

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, Hai-Yang; Kang, Xian-Wei [Academia Sinica, Institute of Physics, Taipei (China)

    2017-09-15

    Based on the predictions of the relevant form factors from the covariant light-front quark model, we show the branching fractions for the D(D{sub s}) → (P, S, V, A) lν{sub l} (l = e or μ) decays, where P denotes the pseudoscalar meson, S the scalar meson with a mass above 1 GeV, V the vector meson and A the axial-vector one. Comparison with the available experimental results are made, and we find an excellent agreement. The predictions for other decay modes can be tested in a charm factory, e.g., the BESIII detector. The future measurements will definitely further enrich our knowledge of the hadronic transition form factors as well as the inner structure of the even-parity mesons (S and A). (orig.)

  10. Analytic parametrizations of the γ*N →N (1440 ) form factors inspired by light-front holography

    Science.gov (United States)

    Ramalho, G.

    2017-09-01

    We present analytic parametrizations for the γ*N →N (1440 ) form factors derived from light-front holography in leading twist approximation. The new parametrizations describe the electromagnetic form factors using analytic functions dependent on the masses of the ρ meson and respective radial excitations, as well as the masses of the nucleon and the resonance N (1440 ). The free parameters of the model, associated with three independent couplings, are interpreted as bare couplings, and are fixed by the nucleon data for large Q2. The proposed parametrizations compare remarkably well with the empirical data for Q2>2 GeV2 , corroborating the dominant role of the valence quark degrees of freedom in the γ*N →N (1440 ) transition.

  11. A Study of Bending Mode Algorithm of Adaptive Front-Lighting System Based on Driver Preview Behavior

    Directory of Open Access Journals (Sweden)

    Zhenhai Gao

    2014-01-01

    Full Text Available The function of adaptive front-lighting system is to improve the lighting condition of the road ahead and driving safety at night. The current system seldom considers characteristics of the driver’s preview behavior and eye movement. To solve this problem, an AFS algorithm modeling a driver’s preview behavior was proposed. According to the vehicle’s state, the driver’s manipulating input, and the vehicle’s future state change which resulted from the driver’s input, a dynamic predictive algorithm of the vehicle’s future track was established based on an optimal preview acceleration model. Then, an experiment on the change rule of the driver’s preview distance with different speeds and different road curvatures was implemented with the eye tracker and the calibration method of the driver’s preview time was established. On the basis of these above theories and experiments, the preview time was introduced to help predict the vehicle’s future track and an AFS algorithm modeling the driver’s preview behavior was built. Finally, a simulation analysis of the AFS algorithm was carried out. By analyzing the change process of the headlamp’s lighting region while bend turning which was controlled by the algorithm, its control effect was verified to be precise.

  12. Multi-Temporal Independent Component Analysis and Landsat 8 for Delineating Maximum Extent of the 2013 Colorado Front Range Flood

    Directory of Open Access Journals (Sweden)

    Stephen M. Chignell

    2015-07-01

    Full Text Available Maximum flood extent—a key data need for disaster response and mitigation—is rarely quantified due to storm-related cloud cover and the low temporal resolution of optical sensors. While change detection approaches can circumvent these issues through the identification of inundated land and soil from post-flood imagery, their accuracy can suffer in the narrow and complex channels of increasingly developed and heterogeneous floodplains. This study explored the utility of the Operational Land Imager (OLI and Independent Component Analysis (ICA for addressing these challenges in the unprecedented 2013 Flood along the Colorado Front Range, USA. Pre- and post-flood images were composited and transformed with an ICA to identify change classes. Flooded pixels were extracted using image segmentation, and the resulting flood layer was refined with cloud and irrigated agricultural masks derived from the ICA. Visual assessment against aerial orthophotography showed close agreement with high water marks and scoured riverbanks, and a pixel-to-pixel validation with WorldView-2 imagery captured near peak flow yielded an overall accuracy of 87% and Kappa of 0.73. Additional tests showed a twofold increase in flood class accuracy over the commonly used modified normalized water index. The approach was able to simultaneously distinguish flood-related water and soil moisture from pre-existing water bodies and other spectrally similar classes within the narrow and braided channels of the study site. This was accomplished without the use of post-processing smoothing operations, enabling the important preservation of nuanced inundation patterns. Although flooding beneath moderate and sparse riparian vegetation canopy was captured, dense vegetation cover and paved regions of the floodplain were main sources of omission error, and commission errors occurred primarily in pixels of mixed land use and along the flood edge. Nevertheless, the unsupervised nature of ICA

  13. Geology of Precambrian rocks and isotope geochemistry of shear zones in the Big Narrows area, northern Front Range, Colorado

    Science.gov (United States)

    Abbott, Jeffrey T.

    1970-01-01

    Rocks within the Big Narrows and Poudre Park quadrangles located in the northern Front Range of Colorado are Precambrian metasedimentary and metaigneous schists and gneisses and plutonic igneous rocks. These are locally mantled by extensive late Tertiary and Quaternary fluvial gravels. The southern boundary of the Log Cabin batholith lies within the area studied. A detailed chronology of polyphase deformation, metamorphism and plutonism has been established. Early isoclinal folding (F1) was followed by a major period of plastic deformation (F2), sillimanite-microcline grade regional metamorphism, migmatization and synkinematic Boulder Creek granodiorite plutonism (1.7 b.y.). Macroscopic doubly plunging antiformal and synformal structures were developed. P-T conditions at the peak of metamorphism were probably about 670?C and 4.5 Kb. Water pressures may locally have differed from load pressures. The 1.4 b.y. Silver Plume granite plutonism was post kinematic and on the basis of petrographic and field criteria can be divided into three facies. Emplacement was by forcible injection and assimilation. Microscopic and mesoscopic folds which postdate the formation of the characteristic mineral phases during the 1.7 b.y. metamorphism are correlated with the emplacement of the Silver Plume Log Cabin batholith. Extensive retrograde metamorphism was associated with this event. A major period of mylonitization postdates Silver Plume plutonism and produced large E-W and NE trending shear zones. A detailed study of the Rb/Sr isotope geochemistry of the layered mylonites demonstrated that the mylonitization and associated re- crystallization homogenized the Rb87/Sr 86 ratios. Whole-rock dating techniques applied to the layered mylonites indicate a probable age of 1.2 b.y. Petrographic studies suggest that the mylonitization-recrystallization process produced hornfels facies assemblages in the adjacent metasediments. Minor Laramide faulting, mineralization and igneous activity

  14. Light at the edge of the universe dispatches from the front lines of cosmology

    CERN Document Server

    Lemonick, Michael D

    2014-01-01

    Will the universe expand forever? Or will it collapse in a Big Crunch within the next few billion years? If the Big Bang theory is correct in presenting the origins of the universe as a smooth fireball, how did the universe come to contain structures as large as the recently discovered ""Great Wall"" of galaxies, which stretches hundreds of millions of light years? Such are the compelling questions that face cosmologists today, and it is the excitement and wonder of their research that Michael Lemonick shares in this lively tour of the current state of astrophysics and cosmology. Here we vis

  15. Universal Long-Range Nanometric Bending of Water by Light

    Science.gov (United States)

    Verma, Gopal; Singh, Kamal P.

    2015-10-01

    Resolving mechanical effects of light on fluids has fundamental importance with wide applications. Most experiments to date on optofluidic interface deformation exploited radiation forces exerted by normally incident lasers. However, the intriguing effects of photon momentum for any configuration, including the unique total internal reflection regime, where an evanescent wave leaks above the interface, remain largely unexplored. A major difficulty in resolving nanomechanical effects has been the lack of a sensitive detection technique. Here, we devise a simple setup whereby a probe laser produces high-contrast Newton-ring-like fringes from a sessile water drop. The mechanical action of the photon momentum of a pump beam modulates the fringes, thus allowing us to perform a direct noninvasive measurement of a nanometric bulge with sub-5-nm precision. Remarkably, a <10 nm difference in the height of the bulge due to different laser polarizations and nonlinear enhancement in the bulge near total internal reflection is isolated. In addition, the nanometric bulge is shown to extend far longer, 100 times beyond the pump spot. Our high precision data validate the century-old Minkowski theory for a general angle and offer potential for novel optofluidic devices and noncontact nanomanipulation strategies.

  16. Resonance excitation and light concentration in sets of dielectric nanocylinders in front of a subwavelength aperture. Effects on extraordinary transmission.

    Science.gov (United States)

    Valdivia-Valero, F J; Nieto-Vesperinas, M

    2010-03-29

    We study the excitation of whispering gallery modes (WGM) in dielectric nanocylinders by light transmitted through a subwavelength slit in a metallic slab. Calculations are done both by the finite elements method and using FDTD simulations. We discuss the effect of that excitation on extraordinary transmission by the slit. In this way, we show the dominant role of the WGMs over the aperture enhanced transmission as regards the resulting transmitted intensity and its concentration inside the cylinders. When sets of these particles are placed in front of the slit, like linear or bifurcated chains, with or without bends, the concentration of WGMs is controlled by designing the geometry parameters, so that these surface waves are coupled by both waveguiding of the nanocylinder eigenmodes and by scattered propagating waves. Also, the choice of the wavelength and polarization of the illumination, allows to select the excitation of either bonding or antibonding states of the field transmitted through the aperture into the particles. These resonances are further enhanced when a beam emerges from the slit due to adding a periodic corrugation in the slab.

  17. The range of attraction for light traps catching Culicoides biting midges (Diptera: Ceratopogonidae).

    Science.gov (United States)

    Kirkeby, Carsten; Græsbøll, Kaare; Stockmarr, Anders; Christiansen, Lasse E; Bødker, René

    2013-03-15

    Culicoides are vectors of e.g. bluetongue virus and Schmallenberg virus in northern Europe. Light trapping is an important tool for detecting the presence and quantifying the abundance of vectors in the field. Until now, few studies have investigated the range of attraction of light traps. Here we test a previously described mathematical model (Model I) and two novel models for the attraction of vectors to light traps (Model II and III). In Model I, Culicoides fly to the nearest trap from within a fixed range of attraction. In Model II Culicoides fly towards areas with greater light intensity, and in Model III Culicoides evaluate light sources in the field of view and fly towards the strongest. Model II and III incorporated the directionally dependent light field created around light traps with fluorescent light tubes. All three models were fitted to light trap collections obtained from two novel experimental setups in the field where traps were placed in different configurations. Results showed that overlapping ranges of attraction of neighboring traps extended the shared range of attraction. Model I did not fit data from any of the experimental setups. Model II could only fit data from one of the setups, while Model III fitted data from both experimental setups. The model with the best fit, Model III, indicates that Culicoides continuously evaluate the light source direction and intensity. The maximum range of attraction of a single 4W CDC light trap was estimated to be approximately 15.25 meters. The attraction towards light traps is different from the attraction to host animals and thus light trap catches may not represent the vector species and numbers attracted to hosts.

  18. The Relative Roles of RONO2 and HNO3 as Sinks of NOX in the Denver Metropolitan Region and Colorado's Front Range

    Science.gov (United States)

    Sparks, T.; Ebben, C. J.; Wooldridge, P. J.; Cohen, R. C.

    2015-12-01

    Measurements of HNO3, total RONO2, NOX, and other relevant species, acquired during the DISCOVER-AQ and FRAPPE field campaigns in the Northern Front Range of Colorado during July-August 2014, are used to assess our understanding of the relative roles of RONO2 and HNO3 formation as sinks of NOX. Although HNO3 production was dominant in the region, RONO2 production was often of order 1/3 of the NOX sink. As NOX emissions decrease, our results indicate RONO2­ chemistry will be increasingly important to descriptions of the chemistry in the region.

  19. Delta: a charge sensitive front-end amplifier with switched gain for low noise, large dynamic range silicon detector readout

    CERN Document Server

    Aspell, P; Bloch, P; Jarron, P; Löfstedt, B; Reynaud, S; Tabbers, P

    2001-01-01

    The design and results of a radiation hard switched gain charge amplifier optimised for a large dynamic range and large input capacitance are described. The peaking time is 25 ns, dynamic ranges are 0.1 - 50 minimum ionizing particles (MIPs) (high gain) and 1 - 400 MIPs (low gain), signal to noise (S/N) > 10 for Cin < 56pF and radiation tolerance to10 Mrads(Si) and 4x10**13 n/cm**2.

  20. The range of attraction for light traps catching Culicoides biting midges (Diptera: Ceratopogonidae)

    DEFF Research Database (Denmark)

    Kirkeby, Carsten; Græsbøll, Kaare; Stockmarr, Anders

    2013-01-01

    Background Culicoides are vectors of e.g. bluetongue virus and Schmallenberg virus in northern Europe. Light trapping is an important tool for detecting the presence and quantifying the abundance of vectors in the field. Until now, few studies have investigated the range of attraction of light...

  1. Watershed management problems and opportunities for the Colorado Front Range ponderosa pine zone: The status of our knowledge

    Science.gov (United States)

    Howard L. Gary

    1975-01-01

    The east flank of the Continental Divide consists largely of open timber stands and grasslands. Soils erode easily after abuse. Precipitation ranges from 15 to 20 inches, about two-thirds from high-intensity storms from April to September. Guidelines are provided for maintaining satisfactorv watershed conditions. The 3- to 5-inch water yields are comparatively small in...

  2. Stability analysis of a horizontal coalbed methane well in the Rocky Mountain Front Ranges of southeast British Columbia, Canada

    Energy Technology Data Exchange (ETDEWEB)

    Gentzis, Thomas [Petron Resources, L.P., Suite 400, 3000 Internet Boulevard, Frisco, TX 75034 (United States)

    2009-01-31

    This study describes a wellbore stability analysis undertaken for a horizontal coalbed methane well in the Mist Mountain Formation, SE British Columbia, Canada. Three triaxial compression tests, with ultrasonic velocities, were conducted on 38-mm-diameter core plugs taken from a large, fresh block of Seam 7. Due to the small size of the tested samples, the laboratory-derived strength values were reduced to reflect the in-situ stress conditions considered relevant for a 156-mm-diameter horizontal well. The vertical stress gradient was calculated by integrating a bulk density log from an offset well. Horizontal maximum and minimum stresses were estimated from regional stress data, whereas formation pressure was estimated on the basis of a local hydrological study. The 2D elastoplastic STABView trademark numerical modeling code was used to forecast horizontal wellbore stability. The sensitivity of the predicted yielded zone size was examined for varying linear and non-linear rock strength criteria, horizontal in-situ stresses, bottom-hole pressures, formation pressure, drilling depth, and wall-coating efficiency. Stability analysis was performed at bottom-hole pressures ranging from overbalanced to underbalanced in order to simulate the conditions expected during drilling and production. The effects of weak bedding planes and varying well trajectories were also investigated. When drilling at 650 m depth under underbalanced to slightly overbalanced conditions, a high probability of getting the drill pipe stuck was predicted. STABView trademark showed that, if the 38-mm-diameter core plug strengths were used directly for forecasting purposes, the predicted yielded zone would be almost 20% overgauge when drilling at balanced conditions. When peak cohesion of coal was reduced by 50% to reflect the conditions expected along weak intervals of a horizontal wellbore, the predicted enlarged borehole was almost 85% overgauge under the same drilling conditions. The most unstable

  3. Electroproduction of lightest nucleon resonances up to Q*2=12 GeV*2 in quark models at light front

    Directory of Open Access Journals (Sweden)

    Obukhovsky I.T.

    2017-01-01

    Full Text Available The lightest nucleon resonances are described at light front as mixed states of the 3q cluster (“quark core” possessing a definite value of the inner orbital momentum L = 0,1 and a hadron molecular state, N+σ or Λ+K. Helicity amplitudes of the resonance electroproduction off the proton are calculated at large Q2 up to 12 GeV2 and compared to the last CLAS data. At this basis we have estimated the probability of quark core in lightest nucleon resonances and predicted the high Q2 behaviour of the resonance electrocoupling.

  4. Breadboard testing of a phase-conjugate engine with an interferometric wave-front sensor and a microelectromechanical systems-based spatial light modulator.

    Science.gov (United States)

    Baker, Kevin L; Stappaerts, Eddy A; Gavel, Don; Wilks, Scott C; Tucker, Jack; Silva, Dennis A; Olsen, Jeff; Olivier, Scot S; Young, Peter E; Kartz, Mike W; Flath, Laurence M; Krulevitch, Peter; Crawford, Jackie; Azucena, Oscar

    2004-10-20

    Laboratory breadboard results of a high-speed adaptive-optics system are presented. The wave-front sensor for the adaptive-optics system is based on a quadrature interferometer, which directly measures the turbulence-induced phase aberrations. The spatial light modulator used in the phase-conjugate engine was a microelectromechanical systems-based piston-only correction device with 1024 actuators. Laboratory experiments were conducted with this system utilizing Kolmogorov phase screens to simulate atmospheric phase distortions. The adaptive-optics system achieved correction speeds in excess of 800 Hz and Strehl ratios greater than 0.5 with the Kolmogorov phase screens.

  5. Breadboard Testing of a Phase Conjugate Engine with an Interferometric Wave-Front Sensor and a MEMS-Based Spatial Light Modulator

    Energy Technology Data Exchange (ETDEWEB)

    Tucker, J; Olsen, J; Minden, M L; Gavel, D; Baker, K L; Stappaerts, E A; Wilks, S C; Silva, D A; Olivier, S S; Young, P E; Kartz, M W; Flath, L M; Azucena, O

    2003-12-08

    Laboratory breadboard results of a high-speed adaptive optics system are presented. The wave-front sensor for the adaptive optics system is based on a quadrature interferometer, which directly measures the turbulence induced phase aberrations. The laboratory experiments were conducted using Kolmogorov phase screens to simulate atmospheric phase distortions with the characterization of these plates presented below. The spatial light modulator used in the phase conjugate engine was a MEMS-based piston-only correction device with 1024 actuators. The overall system achieved correction speeds in excess of 800 hz and Strehl ratios greater than 0.5 with the Kolmogorov phase screens.

  6. Effect of spectral range in surface inactivation of Listeria innocua using broad-spectrum pulsed light.

    Science.gov (United States)

    Woodling, Sarah E; Moraru, Carmen I

    2007-04-01

    Pulsed light (PL) treatment is an alternative to traditional thermal treatment that has the potential to achieve several log-cycle reductions in the concentration of microorganisms. One issue that is still debated is related to what specifically causes cell death after PL treatments. The main objective of this work was to elucidate which portions of the PL range are responsible for bacterial inactivation. Stainless steel coupons with controlled surface properties were inoculated with a known concentration of Listeria innocua in the stationary growth phase and treated with 1 to 12 pulses of light at a pulse rate of 3 pulses per s and a pulse width of 360 micros. The effects of the full spectrum (lambda = 180 to 1,100 nm) were compared with the effects obtained when only certain regions of UV, visible, and near-infrared light were used. The effectiveness of the treatments was determined in parallel by the standard plate count and most-probable-number techniques. At a fluence of about 6 J/cm(2), the full-spectrum PL treatment resulted in a 4.08-log reduction of L. innocua on a Mill finish surface, the removal of lambda light resulted in no lethal effects on L. innocua. Overwhelmingly, the portions of the PL spectrum responsible for bacterial death are the UV-B and UV-C spectral ranges (X light (lambda > 400 nm). This work provides additional supporting evidence that cell death in PL treatment is due to exposure to UV light. Additionally, it was shown that even a minor modification of the light path or the UV light spectrum in PL treatments can have a significant negative impact on the treatment intensity and effectiveness.

  7. Model-assisted forest yield estimation with light detection and ranging

    Science.gov (United States)

    Jacob L. Strunk; Stephen E. Reutebuch; Hans-Erik Andersen; Peter J. Gould; Robert J. McGaughey

    2012-01-01

    Previous studies have demonstrated that light detection and ranging (LiDAR)-derived variables can be used to model forest yield variables, such as biomass, volume, and number of stems. However, the next step is underrepresented in the literature: estimation of forest yield with appropriate confidence intervals. It is of great importance that the procedures required for...

  8. Surface-exposure ages of Front Range moraines that may have formed during the Younger Dryas, 8.2 cal ka, and Little Ice Age events

    Science.gov (United States)

    Benson, L.; Madole, R.; Kubik, P.; McDonald, R.

    2007-01-01

    Surface-exposure (10Be) ages have been obtained on boulders from three post-Pinedale end-moraine complexes in the Front Range, Colorado. Boulder rounding appears related to the cirque-to-moraine transport distance at each site with subrounded boulders being typical of the 2-km-long Chicago Lakes Glacier, subangular boulders being typical of the 1-km-long Butler Gulch Glacier, and angular boulders being typical of the few-hundred-m-long Isabelle Glacier. Surface-exposure ages of angular boulders from the Isabelle Glacier moraine, which formed during the Little Ice Age (LIA) according to previous lichenometric dating, indicate cosmogenic inheritance values ranging from 0 to ???3.0 10Be ka.11Surface-exposure ages in this paper are labeled 10Be; radiocarbon ages are labeled 14C ka, calendar and calibrated radiocarbon ages are labeled cal ka, and layer-based ice-core ages are labeled ka. 14C ages, calibrated 14C ages, and ice core ages are given relative to AD 1950, whereas 10Be ages are given relative to the sampling date. Radiocarbon ages were calibrated using CALIB 5.01 and the INTCAL04 data base Stuiver et al. (2005). Ages estimated using CALIB 5.01 are shown in terms of their 1-sigma range. Subangular boulders from the Butler Gulch end moraine yielded surface-exposure ages ranging from 5 to 10.2 10Be ka. We suggest that this moraine was deposited during the 8.2 cal ka event, which has been associated with outburst floods from Lake Agassiz and Lake Ojibway, and that the large age range associated with the Butler Gulch end moraine is caused by cosmogenic shielding of and(or) spalling from boulders that have ages in the younger part of the range and by cosmogenic inheritance in boulders that have ages in the older part of the range. The surface-exposure ages of eight of nine subrounded boulders from the Chicago Lakes area fall within the 13.0-11.7 10Be ka age range, and appear to have been deposited during the Younger Dryas interval. The general lack of inheritance in

  9. Range and Richness of Vascular Land Plants: The Role of Variable Light

    Science.gov (United States)

    Schultz, Colin

    2010-12-01

    The observation that the number of species decreases—while at the same time the average range of local species increases—with increasing latitude is known within ecological circles as Rapoport's rule. In the AGU monograph Range and Richness of Vascular Land Plants: The Role of Variable Light, former AGU president Peter S. Eagleson seeks a cause for Rapoport's rule. Using a tightly focused analysis, Eagleson delves into the complex interactions that govern ecosystems to propose the primary importance to range and richness of one key variable, the locally incident shortwave radiation. In this interview, Eos talks with Eagleson.

  10. Investigation of the influence of transport from oil and natural gas regions on elevated ozone levels in the northern Colorado front range.

    Science.gov (United States)

    Evans, Jason M; Helmig, Detlev

    2017-02-01

    The Northern Colorado Front Range (NCFR) has been in exceedance of the ozone National Ambient Air Quality Standard (NAAQS) since 2004, which has led to much debate over the sources of ozone precursors to the region, as this area is home to both the Denver, CO, metropolitan area and the Denver-Julesburg Basin, which has experienced rapid growth of oil and natural gas (O&NG) operations and associated emissions. Several recent studies have reported elevated levels of atmospheric volatile organic compounds (VOCs) as a result of O&NG emissions and the potential for significant ozone production from these emissions, despite implementation of stricter O&NG VOC emissions regulations in 2008. Approximately 88% of 1-hr elevated ozone events (>75 ppbv) occur during June-August, indicating that elevated ozone levels are driven by regional photochemistry. Analyses of surface ozone and wind observations from two sites, namely, South Boulder and the Boulder Atmospheric Observatory, both near Boulder, CO, show a preponderance of elevated ozone events associated with east-to-west airflow from regions with O&NG operations in the N-ESE, and a relatively minor contribution of transport from the Denver Metropolitan area to the SE-S. Transport from upwind areas associated with abundant O&NG operations accounts for on the order of 65% (mean for both sites) of 1-hr averaged elevated ozone levels, while the Denver urban corridor accounts for 9%. These correlations contribute to mounting evidence that air transport from areas with O&NG operation has a significant impact on ozone and air quality in the NCFR. This article builds on several previous pieces of research that implied significant contributions from oil and natural gas emissions on ozone production in the Northern Colorado Front Range. By correlating increased ozone events with transport analyses we show that there is a high abundance of transport events with elevated ozone originating from the Denver-Julesburg oil and natural gas

  11. Design and evaluation of wide-range and low-power analog front-end enabling body-implanted devices to monitor charge injection properties

    Science.gov (United States)

    Ito, Keita; Uno, Shoma; Goto, Tatsuya; Takezawa, Yoshiki; Harashima, Takuya; Morikawa, Takumi; Nishino, Satoru; Kino, Hisashi; Kiyoyama, Koji; Tanaka, Tetsu

    2017-04-01

    For safe electrical stimulation with body-implanted devices, the degradation of stimulus electrodes must be considered because it causes the unexpected electrolysis of water and the destruction of tissues. To monitor the charge injection property (CIP) of stimulus electrodes while these devices are implanted, we have proposed a charge injection monitoring system (CIMS). CIMS can safely read out voltages produced by a biphasic current pulse to a stimulus electrode and CIP is calculated from waveforms of the acquired voltages. In this paper, we describe a wide-range and low-power analog front-end (AFE) for CIMS that has variable gain-frequency characteristics and low-power analog-to-digital (A/D) conversion to adjust to the degradation of stimulus electrodes. The designed AFE was fabricated with 0.18 µm CMOS technology and achieved a valuable gain of 20-60 dB, an upper cutoff frequency of 0.2-10 kHz, and low-power interleaving A/D conversion. In addition, we successfully measured the CIP of stimulus electrodes for body-implanted devices using CIMS.

  12. Tuning the Polarization State of Light over a Broad Frequency Range with Metasurfaces

    Science.gov (United States)

    Wang, Mu; Jiang, Shang-Chi; Wang, Zheng-Han; Xiong, Xiang; Peng, Ru-Wen; Nanjing University Team

    Controlling the polarization state, the transmission direction and the phase of light within a confined space is an important issue in optics. By integrating metallic metastructure and dielectric interlayer, it is possible to realize the dispersion-free broadband device on sub-wavelength scale, where the strong response of the metallic structures helps to decrease the device size while the dielectric interlayer helps to eliminate the dispersion simultaneously in both the amplitude and the phase difference of the reflected/transmitted light. As an examples to apply this concept, a broadband quarter-wave plate and a half-wave plate are experimentally demonstrated. By carefully selecting the structural parameters, the polarization state of light can be freely tuned across a broad frequency range, and all of the polarization states on the Poincaré sphere can be realized dispersion free. Some contents of this talk can be found in the following references: [1] S.-C. Jiang, et al., High-efficiency generation of circularly polarized light via symmetry-induced anomalous reflection,Physical Review B 91, 125421 (2015), [2] S.-C. Jiang, et al., Controlling the Polarization State of Light with a Dispersion-Free Metastructure, Physical Review X 4, 021026 (2014), [3] X. Xiong, et al., Metallic stereostructured layer: an approach for broadband polarization state manipulation,Applied Physics Letters 105, 201105 (2014).

  13. Broadband photocurrent enhancement and light-trapping in thin film Si solar cells with periodic Al nanoparticle arrays on the front

    DEFF Research Database (Denmark)

    Uhrenfeldt, C.; Villesen, T. F.; Tetu, A.

    2015-01-01

    Plasmonic resonances in metal nanoparticles are considered candidates for improved thin film Si photovoltaics. In periodic arrays the influence of collective modes can enhance the resonant properties of such arrays. We have investigated the use of periodic arrays of Al nanoparticles placed...... on the front of a thin film Si test solar cell. It is demonstrated that the resonances from the Al nanoparticle array cause a broadband photocurrent enhancement ranging from the ultraviolet to the infrared with respect to a reference cell. From the experimental results as well as from numerical simulations...

  14. Impact of front-of-pack nutrition information and label design on children's choice of two snack foods: Comparison of warnings and the traffic-light system.

    Science.gov (United States)

    Arrúa, Alejandra; Curutchet, María Rosa; Rey, Natalia; Barreto, Patricia; Golovchenko, Nadya; Sellanes, Andrea; Velazco, Guillermo; Winokur, Medy; Giménez, Ana; Ares, Gastón

    2017-09-01

    Research on the relative influence of package features on children's perception of food products is still necessary to aid policy design and development. The aim of the present work was to evaluate the relative influence of two front-of-pack (FOP) nutrition labelling schemes, the traffic light system and Chilean warning system, and label design on children's choice of two popular snack foods in Uruguay, wafer cookies and orange juice. A total of 442 children in grades 4 to 6 from 12 primary schools in Montevideo (Uruguay) participated in the study. They were asked to complete a choice-conjoint task with wafer cookies and orange juice labels, varying in label design and the inclusion of FOP nutrition information. Half of the children completed the task with labels featuring the traffic-light system (n = 217) and the other half with labels featuring the Chilean warning system (n = 225). Children's choices of wafer cookies and juice labels was significantly influenced by both label design and FOP nutritional labels. The relative impact of FOP nutritional labelling on children's choices was higher for the warning system compared to the traffic-light system. Results from the present work stress the need to regulate the design of packages and the inclusion of nutrient claims, and provide preliminary evidence of the potential of warnings to discourage children's choice of unhealthful products. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Does front-of-pack nutrition information improve consumer ability to make healthful choices? Performance of warnings and the traffic light system in a simulated shopping experiment.

    Science.gov (United States)

    Machín, Leandro; Aschemann-Witzel, Jessica; Curutchet, María Rosa; Giménez, Ana; Ares, Gastón

    2018-02-01

    The inclusion of more attention-grabbing and easily interpretable front-of-pack (FOP) nutrition information is one of the public policies that can be implemented to empower consumers to identify unhealthful food products and to make more informed food choices. The aim of the present work was to evaluate the influence of two FOP nutrition labelling schemes - the traffic light labelling and the warning scheme - on consumer food purchases when facing a health goal. The study was conducted with 1182 people from Montevideo (Uruguay), recruited using a Facebook advertisement. Participants were randomly allocated to one of three between-subjects experimental conditions: (i) a control condition with no FOP nutrition information, (ii) FOP nutrition information using a modified version of the traffic light system including information about calorie, saturated fat, sugars and sodium content per portion, and (iii) FOP nutrition information using the Chilean warning system including separate signs for high calorie, saturated fat, sugars and sodium content. Respondents were asked to imagine that they had to purchase food in order to prepare a healthy dinner for themselves and their family, using the website of an online grocery store. Results showed that FOP nutrition information effectively improved the average healthfulness of participants' choices compared to the control condition, both in terms of the average nutritional composition of the purchased products and expenditure in specific product categories. No relevant differences between the effect of the traffic light and the warning system were found. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Highly efficient full-color display based on blue LED backlight and electrochromic light-valve coupled with front-emitting phosphors.

    Science.gov (United States)

    Oh, Jeong Rok; Park, Hoo Keun; Oh, Ji Hye; Kouh, Taejoon; Do, Young Rag

    2011-08-15

    We report a novel full-color display based on the generation of full-color by blue light approach, so called color-by-blue display. This newly proposed color-by-blue light-valve display combines a blue backlight excitation source, a blue light-valve shutter, and front-emitting phosphor pixels. Careful evaluation shows that the detailed display characteristics as well as excellent cycling durability under a low operation voltage of 3 V easily satisfy the requirements for the current display application. Also, we would like to emphasize that the proposed method shows a conversion efficiency of 20%, surpassing the value (≈5%) seen in the typical liquid crystal displays. Although the switching response reported here is slower than in a commercial display module due to the solution-phase electrochromic nature of the shutter used, a response time close to that of a liquid crystal display is highly feasible, as we suggest. © 2011 Optical Society of America

  17. Surface ozone in the Colorado northern Front Range and the influence of oil and gas development during FRAPPE/DISCOVER-AQ in summer 2014

    Directory of Open Access Journals (Sweden)

    L. C. Cheadle

    2017-11-01

    Full Text Available High mixing ratios of ozone (O3 in the northern Front Range (NFR of Colorado are not limited to the urban Denver area but were also observed in rural areas where oil and gas activity is the primary source of O3 precursors. On individual days, oil and gas O3 precursors can contribute in excess of 30 ppb to O3 growth and can lead to exceedances of the EPA O3 National Ambient Air Quality Standard. Data used in this study were gathered from continuous surface O3 monitors for June–August 2013–2015 as well as additional flask measurements and mobile laboratories that were part of the FRAPPE/DISCOVER-AQ field campaign of July–August 2014. Overall observed O3 levels during the summer of 2014 were lower than in 2013, likely due to cooler and damper weather than an average summer. This study determined the median hourly surface O3 mixing ratio in the NFR on summer days with limited photochemical production to be approximately 45–55 ppb. Mobile laboratory and flask data collected on three days provide representative case studies of different O3 formation environments in and around Greeley, Colorado. Observations of several gases (including methane, ethane, CO, nitrous oxide along with O3 are used to identify sources of O3 precursor emissions. A July 23 survey demonstrated low O3 (45–60 ppb while August 3 and August 13 surveys recorded O3 levels of 75–80 ppb or more. August 3 exemplifies influence of moderate urban and high oil and gas O3 precursor emissions. August 13 demonstrates high oil and gas emissions, low agricultural emissions, and CO measurements that were well correlated with ethane from oil and gas, suggesting an oil and gas related activity as a NOx and O3 precursor source. Low isoprene levels indicated that they were not a significant contributor to O3 precursors measured during the case studies.

  18. Bortezomib/dexamethasone followed by autologous stem cell transplantation as front line treatment for light-chain deposition disease.

    Science.gov (United States)

    Tovar, Natalia; Cibeira, Ma Teresa; Rosiñol, Laura; Solé, Manel; de Larrea, Carlos Fernández; Escoda, Lourdes; Rovira, Montserrat; Bladé, Joan

    2012-10-01

    Limited data has been published on the treatment results in patients with light-chain deposition disease (LCDD). Whenever possible, high-dose melphalan followed by autologous stem cell transplantation (ASCT) has been the first treatment option, achieving somehow better results than conventional therapy. However, and based on the promising results obtained by treating patients with light-chain amyloidosis with bortezomib/dexamethasone, new treatment options appear in LCDD. Herein, we describe three patients with LCDD treated with bortezomib/dexamethasone followed by high-dose melphalan and autologous transplantation. We believe that this new approach should be the treatment of choice in this disease. In addition, those patients achieving hematologic complete response after ASCT could benefit from a kidney transplant if the renal impairment requiring dialysis persists. © 2012 John Wiley & Sons A/S.

  19. Modeling of a narrow band pass filter for Bathymetry light detection and ranging (LIDAR) system

    Science.gov (United States)

    Butt, M. A.; Fomchenkov, S. A.; Khonina, S. N.

    2017-11-01

    In this work, a narrow band pass Fabry-Perot filter is designed which can be used in an airborne light detection (ALB) and ranging bathymetry. LIDAR is done by reflecting a pulse laser beam from a target and detecting the round-trip propagation time between the source and the target. ALB systems consist of Nd: YAG laser that emits the pulses at two different wavelengths such as 1064 nm and 532 nm. Infrared pulses at 1064 nm are reflected from the water surface and the green pulses at 532 nm which penetrates the water surface and are reflected from the ground. Filters are desirable to suppress the ambient light that is reflected by the surface of the water or an atmosphere which always enter the detector as a noise. The designed filter shows a high quality with an average transmission of more than 95 % at 532 nm which is considered as practically ideal for water penetration in typical coastal waters.

  20. Frequency-swept Light Sources for Optical Coherence Tomography in the 1060nm range

    DEFF Research Database (Denmark)

    Marschall, Sebastian

    instrument in the biomedical eld, especially in ophthalmology, where it is used for diagnosing retinal diseases. Using light at 1060nm permits deep penetration into the retina and into the layers beneath, the choroid and the sclera. This wavelength range is also benecial for imaging in eyes affected...... by cataract. For the 1060nm band, rapidly tunable lasers|so-called swept sources|are available which enable ultra-high speed acquisition of large three-dimensional datasets. However, these light sources require further improvements: higher output power for sufficient signal quality and wider tuning bandwidth...... for better depth resolution in combination with high tuning speed. We investigate the performance of novel semiconductor laser gain media in fiber-based high-speed swept source prototypes. We demonstrate high output power using a tapered amplifier, and we achieve improved depth resolution with a broadband...

  1. Lunar Laser-Ranging Detection of Light-Speed Anisotropy and Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-04-01

    Full Text Available The Apache Point Lunar Laser-ranging Operation (APOLLO, in NM, can detect pho- ton bounces from retroreflectors on the moon surface to 0.1ns timing resolution. This facility enables not only the detection of light speed anisotropy, which defines a local preferred frame of reference — only in that frame is the speed of light isotropic, but also fluctuations / turbulence (gravitational waves in the flow of the dynamical 3-space rela- tive to local systems / observers. So the APOLLO facility can act as an e ective “gravi- tational wave” detector. A recently published small data set from November 5, 2007, is analysed to characterise both the average anisotropy velocity and the wave / turbulence effects. The results are consistent with some 13 previous detections, with the last and most accurate being from the spacecraft earth-flyby Doppler-shift NASA data.

  2. Lunar Laser-Ranging Detection of Light-Speed Anisotropy and Gravitational Waves

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2010-04-01

    Full Text Available The Apache Point Lunar Laser-ranging Operation (APOLLO, in NM, can detect photon bounces from retroreflectors on the moon surface to 0.1ns timing resolution. This facility enables not only the detection of light speed anisotropy, which defines a local preferred frame of reference - only in that frame is the speed of light isotropic, but also fluctuations/turbulence (gravitational waves in the flow of the dynamical 3-space relative to local systems/observers. So the APOLLO facility can act as an effective "gravitational wave" detector. A recently published small data set from November 5, 2007, is analysed to characterise both the average anisotropy velocity and the wave/turbulence effects. The results are consistent with some 13 previous detections, with the last and most accurate being from the spacecraft earth-flyby Doppler-shift NASA data.

  3. White noise analysis of Phycomyces light growth response system. I. Normal intensity range.

    Science.gov (United States)

    Lipson, E D

    1975-10-01

    The Wiener-Lee-Schetzen method for the identification of a nonlinear system through white gaussian noise stimulation was applied to the transient light growth response of the sporangiophore of Phycomyces. In order to cover a moderate dynamic range of light intensity I, the imput variable was defined to be log I. The experiments were performed in the normal range of light intensity, centered about I0 = 10(-6) W/cm2. The kernels of the Wierner functionals were computed up to second order. Within the range of a few decades the system is reasonably linear with log I. The main nonlinear feature of the second-order kernel corresponds to the property of rectification. Power spectral analysis reveals that the slow dynamics of the system are of at least fifth order. The system can be represented approximately by a linear transfer function, including a first-order high-pass (adaptation) filter with a 4 min time constant and an underdamped fourth-order low-pass filter. Accordingly a linear electronic circuit was constructed to simulate the small scale response characteristics. In terms of the adaptation model of Delbrück and Reichardt (1956, in Cellular Mechanisms in Differentiation and Growth, Princeton University Press), kernels were deduced for the dynamic dependence of the growth velocity (output) on the "subjective intensity", a presumed internal variable. Finally the linear electronic simulator above was generalized to accommodate the large scale nonlinearity of the adaptation model and to serve as a tool for deeper test of the model.

  4. Pulsed ion hall accelerator for investigation of reactions between light nuclei in the astrophysical energy range

    Science.gov (United States)

    Bystritsky, V. M.; Bystritsky, Vit. M.; Dudkin, G. N.; Nechaev, B. A.; Padalko, V. N.

    2017-07-01

    The factors defining the constraints on the current characteristics of the magnetically insulated ion diode (IDM) are considered. The specific current parameters close to the maximum possible ones are obtained for the particular IDM-40 design assigned for acceleration of light ions and investigation of nuclear reactions with small cross sections in the astrophysical energy range (2-40 keV) in the entrance channel. It is experimentally demonstrated that the chosen optimal operation conditions for IDM-40 units provide high stability of the parameters (energy distribution and composition of accelerated particle beams, degree of neutralization) of the accelerated particle flux, which increases during the working pulse.

  5. Warnings as a directive front-of-pack nutrition labelling scheme: comparison with the Guideline Daily Amount and traffic-light systems.

    Science.gov (United States)

    Arrúa, Alejandra; Machín, Leandro; Curutchet, María Rosa; Martínez, Joseline; Antúnez, Lucía; Alcaire, Florencia; Giménez, Ana; Ares, Gastón

    2017-09-01

    Warnings have recently been proposed as a new type of directive front-of-pack (FOP) nutrition labelling scheme to flag products with high content of key nutrients. In the present work, this system was compared with the two most common FOP nutrition labelling schemes (Guideline Daily Amounts (GDA) and traffic-light system) in terms of goal-directed attention, influence on perceived healthfulness and ability to differentiate between products. Design/Setting/Subjects Goal-directed attention to FOP labels was evaluated using a visual search task in which participants were presented with labels on a computer screen and were asked to indicate whether labels with high sodium content were present or absent. A survey with 387 participants was also carried out, in which the influence of FOP labels on perceived healthfulness and ability to identify the healthful alternative were evaluated. Warnings improved consumers' ability to correctly identify a product with high content of a key nutrient within a set of labels compared with GDA and received the highest goal-directed attention. In addition, products with high energy, saturated fat, sugar and/or sodium content that featured warnings on the label were perceived as less healthful than those featuring the GDA or traffic-light system. Warnings and the traffic-light system performed equally well in the identification of the most healthful product. Results from the present work suggest that warnings have potential as directive FOP nutrition labels to improve consumer ability to identify unhealthful products and highlight advantages compared with the traffic-light system.

  6. Gopher eskers, mounds, and stonelines: Evidence of the annual to centennial impacts of gophers in the montane meadows of Colorado's Front Range

    Science.gov (United States)

    Winchell, E. W.; Lombardi, E. M.; Marquez, J. A.; Doak, D. F.; Anderson, R. S.

    2014-12-01

    Within the critical zone on montane hillslopes of Colorado's Front Range, qualitative observations suggest that gophers not only dominate the modern meadow geomorphic rates, but are involved in a geomorphic-ecological feedback system that governs meadow migration on decadal-millennial time scales. Our observations suggest that gopher intensity and location is pertinent to forest/meadow (FM) dynamics. Field mapping of gopher activity as the snow melts in the spring revealed that subnivean tubes ("eskers") are tightly clustered at the FM boundary while mounds generated over the remainder of the summer are concentrated strictly in the meadows. This suggests that gophers spend the winter months at the FM interface and spend the warmer seasons within the meadows. We hypothesize that variations in snow depth drive this spatial-temporal pattern of gopher activity; deeper snow near the FM boundary provides greater insulation, as near-surface ground temperatures in the wind-scoured meadow centers are colder. This motivates our initiation of monitoring and modeling of near-surface temperature across a FM pair. Numerical modeling supports qualitative observations that the following geomorphic-ecological processes are active: seedling establishment and damage, gopher tunneling and resulting mound generation, mound material transport driven by ungulate trampling, vegetative lock-down of mound material, and resulting changes in the soil depth of the landscape. This year's observations suggest that we must add to this mix the annual cycle of the gopher activity. Finally, probing and soil pits within the meadows reveal that on longer timescales gopher activity leads to the development of a well-mixed upper soil layer that is sharply bounded below by high concentrations of large stones ("stone lines") within the glacial till substrate of the hillslopes. The mean diameter of mound surface grains is half that of clasts comprising the stone lines. This motivates documentation of soil

  7. Assessing the role of large wood entrained in the 2013 Colorado Front Range flood in ongoing channel response and reservoir management

    Science.gov (United States)

    Bennett, Georgina; Rathburn, Sara; Ryan, Sandra; Wohl, Ellen; Blair, Aaron

    2016-04-01

    Considerable quantities of large wood (LW) may be entrained during floods with long lasting impacts on channel morphology, sediment and LW export, and downstream reservoir management. Here we present an analysis of LW entrained by an extensive flood in Colorado, USA. Over a 5 day period commencing 9th September 2013, up to 450 mm of rain, or ~1000% of the monthly average, fell in catchments spanning a 100-km-wide swath of the Colorado Front Range resulting in major flooding. Catchment response was dramatic, with reports of 100s - 1000s of years of erosion, destruction of infrastructure and homes, and sediment and LW loading within reservoirs. One heavily impacted catchment is the North St Vrain, draining 250km2 of the South Platte drainage basin. In addition to widespread channel enlargement, remote imagery reveals hundreds of landslides that delivered sediment and LW to the channel and ultimately to Ralph Price Reservoir, which provides municipal water to Longmont. The City of Longmont facilitated the removal of ~1050 m3 of wood deposited at the reservoir inlet by the flood but the potential for continued movement of large wood in the catchment presents an on-going concern for reservoir management. In collaboration with the City of Longmont, our objectives are (1) to quantify the volume of wood entrained by the flood and still stored along the channel, (2) characterize the size and distribution of LW deposits and (3) determine their role in ongoing catchment flood response and recovery. We utilize freely available pre and post flood NAIP 4-band imagery to calculate a normalized differential vegetation index (NDVI) difference map with which we calculate the area of vegetation entrained by the flood. We combine this with field assessments and a map of vegetation type automatically classified from optical satellite imagery to estimate the total flood-entrained volume of wood. Preliminary testing of 'stream selfies' - structure from motion imaging of LW deposits using

  8. [Influence of human body target's spectral characteristics on visual range of low light level image intensifiers].

    Science.gov (United States)

    Zhang, Jun-Ju; Yang, Wen-Bin; Xu, Hui; Liu, Lei; Tao, Yuan-Yaun

    2013-11-01

    To study the effect of different human target's spectral reflective characteristic on low light level (LLL) image intensifier's distance, based on the spectral characteristics of the night-sky radiation and the spectral reflective coefficients of common clothes, we established a equation of human body target's spectral reflective distribution, and analyzed the spectral reflective characteristics of different human targets wearing the clothes of different color and different material, and from the actual detection equation of LLL image intensifier distance, discussed the detection capability of LLL image intensifier for different human target. The study shows that the effect of different human target's spectral reflective characteristic on LLL image intensifier distance is mainly reflected in the average reflectivity rho(-) and the initial contrast of the target and the background C0. Reflective coefficient and spectral reflection intensity of cotton clothes are higher than polyester clothes, and detection capability of LLL image intensifier is stronger for the human target wearing cotton clothes. Experimental results show that the LLL image intensifiers have longer visual ranges for targets who wear cotton clothes than targets who wear same color but polyester clothes, and have longer visual ranges for targets who wear light-colored clothes than targets who wear dark-colored clothes. And in the full moon illumination conditions, LLL image intensifiers are more sensitive to the clothes' material.

  9. Fluid circulation and diagenesis of carbonated and sandstone reservoirs in the fronts and fore-lands of folded chains: the Salt Range case - Poswar (Pakistan); Circulation des fluides et diagenese des reservoirs carbonates et greseux dans les fronts de chaines plissees et leur avant pays: le cas du Salt Range - Poswar (Pakistan)

    Energy Technology Data Exchange (ETDEWEB)

    Benchilla, L.

    2003-05-01

    The Salt Range-Poswar Province is located in the western foothills of the Himalayas, in northern Pakistan. It extends over 170 km from the Main Boundary Thrust (MBT) in the north to the Salt Range in the south. The Salt Range itself is dominantly an ENE-trending structure, but it comprises also a NNW-trending lateral ramp which connects to the west with the Surghar Range. The Salt Range constitutes the frontal part of a detached allochthonous thrust sheet. The sedimentary cover is indeed entirely detached from its substratum along Infracambrian salt horizons. Palaeozoic to Eocene platform series are well exposed in the hanging wall, whereas Neogene molasse has been extensively under-thrust in the footwall of this large over-thrust. The North Potwar Basin is bordered by the Khari-Murat Ridge and coeval back-thrusts in the south, by the northern flank of the Soan syncline in the southeast, and by the MBT in the north. In addition to Neogene outcrops, it also comprises a number of surface anticlines and thrust fronts along which the Eocene platform carbonates are exposed. The Datta Formation is the main Jurassic oil reservoir in the Potwar Basin. It is a fluvio-deltaic deposit which comprises large porous and permeable channels associated to many-calcareous interbeds. The formations crop out well in both the Nammal and Chichali Gorges. The oil field of Toot, located in the western part of the basin, is producing from this reservoir. The petrographic observations show that diagenesis occurred mainly early and was controlled by the fluvio-deltaic environment. (author)

  10. Front cover

    Directory of Open Access Journals (Sweden)

    Prof.Dr. Hasan KÜÇÜKBAY

    2017-06-01

    Full Text Available This is the front cover of JOTCSA 4(2, which contains numerous fruitful information. Kindly read the contents and if you need to ask questions, contact the managing editor (Dr. Akkurt at jotcsa@turchemsoc.org or the chief editor (Prof. Dr. Küçükbay. Let us see each other in the next issue...

  11. A new high dynamic range ROIC with smart light intensity control unit

    Science.gov (United States)

    Yazici, Melik; Ceylan, Omer; Shafique, Atia; Abbasi, Shahbaz; Galioglu, Arman; Gurbuz, Yasar

    2017-05-01

    This journal presents a new high dynamic range ROIC with smart pixel which consists of two pre-amplifiers that are controlled by a circuit inside the pixel. Each pixel automatically decides which pre-amplifier is used according to the incoming illumination level. Instead of using single pre-amplifier, two input pre-amplifiers, which are optimized for different signal levels, are placed inside each pixel. The smart circuit mechanism, which decides the best input circuit according to the incoming light level, is also designed for each pixel. In short, an individual pixel has the ability to select the best input amplifier circuit that performs the best/highest SNR for the incoming signal level. A 32 × 32 ROIC prototype chip is designed to demonstrate the concept in 0.18 μ m CMOS technology. The prototype is optimized for NIR and SWIR bands. Instead of a detector, process variation optimized current sources are placed inside the ROIC. The chip achieves minimum 8.6 e- input referred noise and 98.9 dB dynamic range. It has the highest dynamic range in the literature in terms of analog ROICs for SWIR band. It is operating in room temperature and power consumption is 2.8 μ W per pixel.

  12. Recent northward range expansion promotes song evolution in a passerine bird, the Light-vented Bulbul.

    Science.gov (United States)

    Xing, X Y; Alström, P; Yang, X J; Lei, F M

    2013-04-01

    In common with human speech, song is culturally inherited in oscine passerine birds ('songbirds'). Intraspecific divergence in birdsong, such as development of local dialects, might be an important early step in the speciation process. It is therefore vital to understand how songs diverge, especially in founding populations. The northward expansion of the Light-vented Bulbul Pycnonotus sinensis (J. F. Gmelin, 1789) into north China in the last 30 years provides an excellent opportunity to study birdsong evolution. We compared ~4400 songs from newly established northern populations with ~2900 songs from southern populations to evaluate song divergence after recent expansion. The total pool of syllables and especially song types was considerably smaller in the north than in the south, indicating 'founder effects' in the new population. The ancestral pattern of mosaic song dialects changed into a pattern of wide geographical sharing of a few song types and syllables, likely the result of fewer geographical barriers to 'meme flow', and the recent spread across a large area in the north. Our results suggest that song evolution and vocal trait shifts can arise rapidly after range expansion, and that in the Light-vented Bulbul 'founder effects', geographical isolation, and recent rapid expansions played important roles in the evolution of song dialects. © 2013 The Authors. Journal of Evolutionary Biology © 2013 European Society For Evolutionary Biology.

  13. Precision and shortcomings of yaw error estimation using spinner-based light detection and ranging

    DEFF Research Database (Denmark)

    Kragh, Knud Abildgaard; Hansen, Morten Hartvig; Mikkelsen, Torben

    2013-01-01

    When extracting energy from the wind using horizontal axis wind turbines, the ability to align the rotor axis with the mean wind direction is crucial. In previous work, a method for estimating the yaw error based on measurements from a spinner mounted light detection and ranging (LIDAR) device......, the shortcomings of using a spinner mounted LIDAR for yaw error estimation are discussed. The extended simulation study shows that with the applied method, the yaw error can be estimated with a precision of a few degrees, even in highly turbulent flows. Applying the method to experimental data reveals an average...... yaw error of approximately 9° during a period of 2 h, and good correlation is seen between LIDAR-based estimates and met-mast data. The final discussion suggests a number of challenges of the method when applied to measurements in complex flow. Copyright © 2012 John Wiley & Sons, Ltd....

  14. High Precision Stokes Polarimetry for Scattering Light using Wide Dynamic Range Intensity Detector

    Directory of Open Access Journals (Sweden)

    Shibata Shuhei

    2015-01-01

    Full Text Available This paper proposes a Stokes polarimetry for scattering light from a sample surface. To achieve a high accuracy measurement two approaches of an intensity detector and analysis algorism of a Stokes parameter were proposed. The dynamic range of this detector can achieve up to 1010 by combination of change of neutral-density (ND filters having different density and photon counting units. Stokes parameters can be measured by dual rotating of a retarder and an analyzer. The algorism of dual rotating polarimeter can be calibrated small linear diattenuation and linear retardance error of the retarder. This system can measured Stokes parameters from −20° to 70° of its scattering angle. It is possible to measure Stokes parameters of scattering of dust and scratch of optical device with high precision. This paper shows accuracy of this system, checking the polarization change of scattering angle and influence of beam size.

  15. Does light pollution alter daylength? A test using light loggers on free-ranging European blackbirds (Turdus merula).

    Science.gov (United States)

    Dominoni, Davide M; Partecke, Jesko

    2015-05-05

    Artificial light at night is one of the most apparent environmental changes accompanying anthropogenic habitat change. The global increase in light pollution poses new challenges to wild species, but we still have limited understanding of the temporal and spatial pattern of exposure to light at night. In particular, it has been suggested by several studies that animals exposed to light pollution, such as songbirds, perceive a longer daylength compared with conspecifics living in natural darker areas, but direct tests of such a hypothesis are still lacking. Here, we use a combination of light loggers deployed on individual European blackbirds, as well as automated radio-telemetry, to examine whether urban birds are exposed to a longer daylength than forest counterparts. We first used activity data from forest birds to determine the level of light intensity which defines the onset and offset of daily activity in rural areas. We then used this value as threshold to calculate the subjective perceived daylength of both forest and urban blackbirds. In March, when reproductive growth occurs, urban birds were exposed on average to a 49-min longer subjective perceived daylength than forest ones, which corresponds to a 19-day difference in photoperiod at this time of the year. In the field, urban blackbirds reached reproductive maturity 19 day earlier than rural birds, suggesting that light pollution could be responsible of most of the variation in reproductive timing found between urban and rural dwellers. We conclude that light at night is the most relevant change in ambient light affecting biological rhythms in avian urban-dwellers, most likely via a modification of the perceived photoperiod. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  16. Limited attractant range of the black-light suction trap for the capture of Culicoides biting midges (Dipetera: Ceratopogonidae)

    NARCIS (Netherlands)

    Elbers, A.R.W.; Meiswinkel, R.

    2016-01-01

    The suction light trap (LT) is a standard tool used to capture Culicoides biting midges, when estimating abundances, and mapping species ranges. The exact range of attraction of the LT is in dispute, however, with several studies indicating the range to vary widely, between 4 and 50 m. In this

  17. B_c→ B_{sJ} form factors and B_c decays into B_{sJ} in covariant light-front approach

    Science.gov (United States)

    Shi, Yu-Ji; Wang, Wei; Zhao, Zhen-Xing

    2016-10-01

    We suggest to study the Bs and its excitations B_{sJ} in the B_c decays. We calculate the B_c→ B_{sJ} and B_c→ BJ form factors within the covariant light-front quark model, where the B_{sJ} and BJ denote an s-wave or p-wave bar{b}s and bar{b}d meson, respectively. The form factors at q^2=0 are directly computed while their q^2-distributions are obtained by extrapolation. The derived form factors are then used to study semileptonic B_c→ (B_{sJ},BJ)bar{ℓ }ν decays, and nonleptonic B_c→ B_{sJ}π . Branching fractions and polarizations are predicted in the standard model. We find that the branching fractions are sizable and might be accessible at the LHC experiment and future high-energy e^+e^- colliders with a high luminosity at the Z-pole. The future experimental measurements are helpful to study the nonperturbative QCD dynamics in the presence of a heavy spectator and also of great value for the study of spectroscopy.

  18. Spacelike and timelike form factors for the (π0,η ,η')→γ*γ transitions in the light-front quark model

    Science.gov (United States)

    Choi, Ho-Meoyng; Ryu, Hui-Young; Ji, Chueng-Ryong

    2017-09-01

    We investigate the (π0,η ,η')→γ*γ transitions both for the spacelike region and the timelike region using the light-front quark model (LFQM). In particular, we present the new direct method to explore the timelike region without resorting to mere analytic continuation from the spacelike region to the timelike region. Our direct calculation in timelike region shows the complete agreement not only with the analytic continuation result from the spacelike region but also with the result from the dispersion relation between the real and imaginary parts of the form factor. For the low energy regime, we compare our LFQM results of the transition form factors (TFFs) for the low timelike momentum transfer region and the slope parameters at q2=0 with the recent experimental data from the Dalitz decays of (π0,η ,η'). For the high energy regime, we incorporate the QCD factorization in our LFQM to examine the asymptotic behavior of TFFs both for the spacelike region and the timelike region. We compare our results with the available experimental data.

  19. Pick-and-place guidance utilizing an integrated control method and structured light ranging

    Science.gov (United States)

    Riekki, Jukka P.; Roening, Juha; Silven, Olli; Pietikaeinen, Matti; Koivunen, Visa

    1992-02-01

    This paper presents a vision-guided control system for an industrial robot capable of picking up an object, moving it to a goal, and placing it there. Tasks given to the control system are based on imperfect knowledge about the environment. The control system corrects the task parameters by matching them against range information gained from the environment. The control system is part of a larger system, which includes a high-level goal-oriented planner. The planner consists of hierarchically organized planning-executing-monitoring triplets, which execute given tasks by dividing them into subtasks, by sending the subtasks either to other triplets or to the control system described in this paper, and by monitoring the execution of the subtasks. The planner sees the robot and the control system as an intelligent robot capable of executing pick-and-place tasks in a dynamic, partly unknown environment. This paper presents the results of the testing of the control system with an industrial 6-axis robot and a structured light-based range sensor. Also the principle of calibrating the robot and the sensor is presented.

  20. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    Science.gov (United States)

    Binetti, Enrico; Striccoli, Marinella; Sibillano, Teresa; Giannini, Cinzia; Brescia, Rosaria; Falqui, Andrea; Comparelli, Roberto; Corricelli, Michela; Tommasi, Raffaele; Agostiano, Angela; Curri, M. Lucia

    2015-10-01

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700-850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  1. Tuning light emission of PbS nanocrystals from infrared to visible range by cation exchange

    KAUST Repository

    Binetti, Enrico

    2015-10-27

    Colloidal semiconductor nanocrystals, with intense and sharp-line emission between red and near-infrared spectral regions, are of great interest for optoelectronic and bio-imaging applications. The growth of an inorganic passivation layer on nanocrystal surfaces is a common strategy to improve their chemical and optical stability and their photoluminescence quantum yield. In particular, cation exchange is a suitable approach for shell growth at the expense of the nanocrystal core size. Here, the cation exchange process is used to promote the formation of a CdS passivation layer on the surface of very small PbS nanocrystals (2.3 nm in diameter), blue shifting their optical spectra and yielding luminescent and stable nanostructures emitting in the range of 700–850 nm. Structural, morphological and compositional investigation confirms the nanocrystal size contraction after the cation-exchange process, while the PbS rock-salt crystalline phase is retained. Absorption and photoluminescence spectroscopy demonstrate the growth of a passivation layer with a decrease of the PbS core size, as inferred by the blue-shift of the excitonic peaks. The surface passivation strongly increases the photoluminescence intensity and the excited state lifetime. In addition, the nanocrystals reveal increased stability against oxidation over time. Thanks to their absorption and emission spectral range and the slow recombination dynamics, such highly luminescent nano-objects can find interesting applications in sensitized photovoltaic cells and light-emitting devices.

  2. Corals through the light : phylogenetics, functional diversity and adaptive strategies of coral-symbiont associations over a large depth range

    NARCIS (Netherlands)

    Rodrigues Frade, P.

    2009-01-01

    Light constitutes the main energy source in the coral reef ecosystem, with its intensity dramatically reduced with increasing depth over the reef slope. How do corals thrive across these acute light gradients that exist over large depth ranges? This and many more questions are addressed throughout

  3. Application of the light-front holographic wavefunction for heavy-light pseudoscalar meson in Bd,s → Dd,sP decays

    Science.gov (United States)

    Chang, Qin; Xu, Shuai; Chen, Lingxin

    2017-08-01

    In this paper we extend our analyses of the decay constant and distribution amplitude with an improved holographic wavefunction to the heavy-light pseudoscalar mesons. In the evaluations, the helicity-dependence of the holographic wavefunction is considered; and an independent mass scale parameter is employed to moderate the strong suppression induced by the heavy quark. Under the constraints from decay constants and masses of pseudoscalar mesons, the χ2-analyses for the holographic parameters exhibit a rough consistence with the results obtained by fitting the Regge trajectory. With the fitted parameters, the results for the decay constants and distribution amplitudes are presented. We then show their application in evaluating the Bd,s →Dd,s P decays, in which the power-suppressed spectator scattering and weak annihilation corrections are first estimated. Numerically, the spectator scattering and weak annihilation corrections present a negative shift of about 0.7% on the branching fractions; while, the predictions are still larger than the experimental data. Such small negative shift confirms the estimation based on the power counting rules.

  4. Lightness perception in high dynamic range images: local and remote luminance effects.

    Science.gov (United States)

    Allred, Sarah R; Radonjic, Ana; Gilchrist, Alan L; Brainard, David H

    2012-02-08

    We measured the perceived lightness of target patches embedded in high dynamic range checkerboards. We independently varied the luminance of checks immediately surrounding the test and those remote from it. The data establish context transfer functions (CTFs) that characterize perceptual matches across checkerboard contexts. Several features of the CTFs are broadly consistent with previous research: Matched luminance decreases when overall context luminance decreases; matched luminance increases when overall context luminance increases; manipulating context locations near the target has a greater effect than manipulating locations far from the target patch. The measured CTFs are not well described, however, by changes with context in multiplicative gain alone or by changes in both multiplicative and subtractive adaptation parameters. We were able to fit the data with a three-parameter model of adaptation. This allowed us to characterize the CTFs by specifying the luminances that appeared white, black, and gray (white point, black point, and gray point, respectively). The white and black points depended additively on the local and remote contrasts, but accounting for the gray point required an interaction term. Analysis of this effect suggests that the target patch itself must be included in a description of the visual context.

  5. Microcavity light emitting diodes in the visible red and near infrared wavelength range

    OpenAIRE

    Joray, Reto; Ilegems, Marc

    2005-01-01

    It was about 125 years ago that the light bulb was commercialized by Thomas Edison. No doubt a brilliant invention at the time, today its low power conversion efficiency is one of the reasons why lighting in the western world has such high energy consumption. Thus, the potential for saving energy is enormous in this area. The introduction of halogen, discharge and fluorescent lamps has lead to certain efficiency improvements, however more than half of the energy is still lost as heat. Light-e...

  6. Displacement Processes in Stable Drainage Fronts

    Science.gov (United States)

    Breen, S. J.; Pride, S. R.; Manga, M.

    2016-12-01

    Drainage fronts are stabilized at large bond number, when a low density nonwetting fluid displaces a high density wetting fluid from above. This is an ideal flow scenario for studying the correspondence between pore scale processes and continuum models because the front is a persistent macroscale feature that is propagated by discrete, multiplepore scale displacements. We present new observations of stable air/water drainage in thin, threedimensional, poured bead packs at varying capillary number. With backlighting and a high speed camera, we observe short range front velocities that are an order of magnitude larger than bulk pore velocity, consistent with previous studies in ordered 2D structures. We also quantify displacement lengths and front width. For comparison to continuum simulations, we measure saturation by light transmission continuously over a series of 1 cm length voxels. We focus on the critical nonwetting saturation (CNS, or "emergence point") at which voxels are percolated by air and continuum air permeability becomes nonzero. We find that mean CNS is capillary number dependent even at large bond number, with larger CNS at lower capillary number. Continuum simulations with an equivalent discretization demonstrate that CNS is a significant source of uncertainty for predictions of the time and saturation profile at chamber-length air breakthrough.

  7. Single-photon pulsed-light indirect time-of-flight 3D ranging.

    Science.gov (United States)

    Bellisai, S; Bronzi, D; Villa, F A; Tisa, S; Tosi, A; Zappa, F

    2013-02-25

    "Indirect" time-of-flight is one technique to obtain depth-resolved images through active illumination that is becoming more popular in the recent years. Several methods and light timing patterns are used nowadays, aimed at improving measurement precision with smarter algorithms, while using less and less light power. Purpose of this work is to present an indirect time-of-flight imaging camera based on pulsed-light active illumination and a 32 × 32 single-photon avalanche diode array with an improved illumination timing pattern, able to increase depth resolution and to reach single-photon level sensitivity.

  8. A framework for automatic feature extraction from airborne light detection and ranging data

    Science.gov (United States)

    Yan, Jianhua

    Recent advances in airborne Light Detection and Ranging (LIDAR) technology allow rapid and inexpensive measurements of topography over large areas. Airborne LIDAR systems usually return a 3-dimensional cloud of point measurements from reflective objects scanned by the laser beneath the flight path. This technology is becoming a primary method for extracting information of different kinds of geometrical objects, such as high-resolution digital terrain models (DTMs), buildings and trees, etc. In the past decade, LIDAR gets more and more interest from researchers in the field of remote sensing and GIS. Compared to the traditional data sources, such as aerial photography and satellite images, LIDAR measurements are not influenced by sun shadow and relief displacement. However, voluminous data pose a new challenge for automated extraction the geometrical information from LIDAR measurements because many raster image processing techniques cannot be directly applied to irregularly spaced LIDAR points. In this dissertation, a framework is proposed to filter out information about different kinds of geometrical objects, such as terrain and buildings from LIDAR automatically. They are essential to numerous applications such as flood modeling, landslide prediction and hurricane animation. The framework consists of several intuitive algorithms. Firstly, a progressive morphological filter was developed to detect non-ground LIDAR measurements. By gradually increasing the window size and elevation difference threshold of the filter, the measurements of vehicles, vegetation, and buildings are removed, while ground data are preserved. Then, building measurements are identified from no-ground measurements using a region growing algorithm based on the plane-fitting technique. Raw footprints for segmented building measurements are derived by connecting boundary points and are further simplified and adjusted by several proposed operations to remove noise, which is caused by irregularly

  9. Different Narrow-Band Light Ranges Alter Plant Secondary Metabolism and Plant Defense Response to Aphids.

    Science.gov (United States)

    Rechner, Ole; Neugart, Susanne; Schreiner, Monika; Wu, Sasa; Poehling, Hans-Michael

    2016-10-01

    Light of different wavelengths affects various physiological processes in plants. Short-wavelength radiation (like UV) can activate defense pathways in plants and enhance the biosynthesis of secondary metabolites (such as flavonoids and glucosinolates) responsible for resistance against certain herbivorous insects. The intensity of light-induced, metabolite-based resistance is plant- and insect species-specific and depends on herbivore feeding guild and specialization. In this study, broccoli (Brassica oleracea var. italica) plants were grown for 4 weeks in a climate chamber under conventional fluorescent tubes and were additionally treated with UV-B (310 nm), UV-A (365 or 385 nm), or violet (420 nm) light generated with UV-B tubes or light-emitting diodes (LEDs). The objective was to determine the influence of narrow bandwidths of light (from UV-B to violet) on plant secondary metabolism and on the performance of the cabbage aphid Brevicoryne brassicae (a specialist) and the green peach aphid Myzus persicae (a generalist). Among flavonol glycosides, specific quercetin and kaempferol glycosides increased markedly under UV-B, while among glucosinolates only 4-methoxy-3-indolylmethyl showed a 2-fold increase in plants exposed to UV-B and UV-A. The concentration of 3-indolylmethyl glucosinolate in broccoli plants increased with UV-B treatment. Brevicoryne brassicae adult weights and fecundity were lower on UV-B treated plants compared to UV-A or violet light-treated plants. Adult weights and fecundity of M. persicae were increased under UV-B and UV-A treatments. When specific light wavelengths are used to induce metabolic changes in plants, the specificity of the induced effects on herbivores should be considered.

  10. Applying inventory methods to estimate aboveground biomass from satellite light detection and ranging (LiDAR) forest height data

    Science.gov (United States)

    Sean P. Healey; Paul L. Patterson; Sassan Saatchi; Michael A. Lefsky; Andrew J. Lister; Elizabeth A. Freeman; Gretchen G. Moisen

    2012-01-01

    Light Detection and Ranging (LiDAR) returns from the spaceborne Geoscience Laser Altimeter (GLAS) sensor may offer an alternative to solely field-based forest biomass sampling. Such an approach would rely upon model-based inference, which can account for the uncertainty associated with using modeled, instead of field-collected, measurements. Model-based methods have...

  11. Mobility of Chromophores Absorbing Light in the 320-420 nm Range in Transparent and Cataract Lens Tissue

    Science.gov (United States)

    Halets-Bui, I. V.; Sukhodol, A. A.; Shcharbin, D. G.

    2014-11-01

    We have analyzed the spectral and kinetic characteristics of phosphorescence at room temperature on a millisecond time scale for transparent and cataract lens tissues. We have studied the nature of the change (with age and with cataract development in the lens tissues) in the molecular mobility of the products absorbing light in the 320-420 nm range.

  12. Delta a charge sensitive front-end amplifier with switched gain for low-noise, large dynamic range silicon detector readout

    CERN Document Server

    Aspell, P; Bloch, P; Jarron, Pierre; Löfstedt, B; Reynaud, S; Tabbers, P

    2001-01-01

    The design and results of a radiation hard switched gain charge amplifier optimised for a large dynamic range and large input capacitance are described. The peaking time is 25 ns, dynamic ranges are 0.1-50 minimum ionising particles (MIPs) (high gain) and 1-400 MIPs (low gain), signal to noise (S/N)>10 for C/sub m/<56 pF and radiation tolerance to 10 Mrads(Si) and 4*10/sup 13/ n cm/sup -2/. (5 refs).

  13. Long range excitonic transport in a biomimetic system inspired by the bacterial light-harvesting apparatus

    Science.gov (United States)

    Harel, Elad

    2012-05-01

    Photosynthesis, the process by which energy from sunlight drives cellular metabolism, relies on a unique organization of light-harvesting and reaction center complexes. Recently, the organization of light-harvesting LH2 complexes and dimeric reaction center-light-harvesting I-PufX core complexes in membranes of purple non-sulfur bacteria was revealed by atomic force microscopy [S. Bahatyrova et al., Nature (London) 430, 1058 (2004)]. Here, we discuss optimal exciton transfer in a biomimetic system closely modeled on the structure of LH2 and its organization within the membrane using a Markovian quantum model with dissipation and trapping added phenomenologically. In a deliberate manner, we neglect the high level detail of the bacterial light-harvesting complex and its interaction with the phonon bath in order to elucidate a set of design principles that may be incorporated in artificial pigment-scaffold constructs in a supramolecular assembly. We show that our scheme reproduces many of the most salient features found in their natural counterpart and may be largely explained by simple electrostatic considerations. Most importantly, we show that quantum effects act primarily to enforce robustness with respect to spatial and spectral disorder between and within complexes. The implications of such an arrangement are discussed in the context of biomimetic photosynthetic analogs capable of transferring energy efficiently across tens to hundreds of nanometers.

  14. Entrainment range of the suprachiasmatic nucleus affected by the difference in the neuronal amplitudes between the light-sensitive and light-insensitive regions

    Science.gov (United States)

    Gu, Changgui; Yang, Huijie; Ruan, Zhongyuan

    2017-04-01

    Mammals not only can be synchronized to the natural 24-h light-dark cycle, but also to a cycle with a non-24-h period. The range of the period of the external cycle, for which the animals can be entrained to, is called the entrainment range, which differs among species. The entrainment range as a characteristic of the animal is determined by the main circadian clock, i.e., the suprachiasmatic nucleus (SCN) in the brain. The SCN is composed of ˜10 000 heterogeneous neurons, which can be divided into two subgroups, i.e., the ventrolateral subgroup (VL) directly receiving the light information from the retina and relaying the information to the dorsomedial subgroup (DM). Among the SCN neurons, the amplitudes are different; however, it is unclear that the amplitude is related to the location of the neurons in experiments. In the present study, we examined the effect of the difference in the neuronal amplitude between the VL and the DM on the entrainment range of the SCN, based on a mathematical model, i.e., the Poincaré model, which is used to describe the circadian clock. We find that the maximal entrainment range is obtained when the difference is equal to a critical point. If the difference of the amplitudes of the VL neurons to the amplitudes of the DM neurons is smaller than a critical point, with the increase of the difference, the entrainment range of the SCN increases, while if the difference is larger than the critical point, the entrainment range decreases with the increase of the difference. Our finding may give a potential explanation for the diversity of the entrainment range among species.

  15. Range-energy relation, range straggling and response function of CsI(Tl), BGO and GSO(Ce) scintillators for light ions

    CERN Document Server

    Avdeichikov, V; Jakobsson, B; Rodin, A M; Ter-Akopian, G M

    2000-01-01

    Range-energy relations and range straggling of sup 1 sup , sup 2 sup , sup 3 H and sup 4 sup , sup 6 He isotopes with the energy approx 50A MeV are measured for the CsI(Tl), BGO and GSO(Ce) scintillators with an accuracy better than 0.2% and 5%, respectively. The Si-Sci/PD telescope was exposed to secondary beams from the mass separator ACCULINNA. The experimental technique is based on the registration of the 'jump' in the amplitude of the photodiode signal for ions passing through the scintillation crystal. Light response of the scintillators for ions 1<=Z<=4 is measured in energy range (5-50)A MeV, the results are in good agreement with calculations based on Birks model. The energy loss straggling for particles with DELTA E/E=0.01-0.50 and mass up to A=10 in 286 mu m DELTA E silicon detector is studied and compared with theoretical prescriptions. The results allow a precise absolute calibration of the scintillation crystal and to optimize the particle identification by the DELTA E-E(Sci/PD) method.

  16. The safety and efficacy of front-firing green-light laser endoscopic en bloc photoselective vapo-enucleation of non-muscle-invasive bladder cancer

    Science.gov (United States)

    Cheng, Bo; Qiu, Xiaofu; Li, Huanhui; Yang, Guosheng

    2017-01-01

    Purpose Laser therapy provides an alternative option for treating non-muscle-invasive bladder cancer (NMIBC). However, the clinical evidence for potassium-titanyl-phosphate (KTP) laser en bloc resection is still limited. Here, we investigated the efficacy and safety of the 120-W front-firing KTP laser for the treatment of NMIBC. Methods A total of 64 patients with NMIBC treated with either a 120-W front-firing KTP-photoselective vapo-enucleation of the bladder tumor (PVEBT, n=34) or transurethral resection of the bladder tumor (TURBT, n=30) were included. En bloc resection was applied to the patients in PVEBT group. Results There was no significant difference in rinsing time (P=0.292), indwelling catheter (P=0.080), pathologic type, and T stage (P=0.870) between the two groups. Compared with the TURBT group, patients treated with PVEBT had a shorter hospitalization stay (P=0.044), a shorter operation time (P=0.008), and a lower muscle miss rate (P=0.044). PVEBT is superior to TURBT in terms of the rate of 1-year recurrence (P=0.015) and tumor grade progression rate (P=0.019). Conclusion The 120-W front-firing KTP laser en bloc enucleation technique is a safe and feasible procedure for treating patients with NMIBC. Further external validation in larger cohorts with a long follow-up period is warranted. PMID:28860782

  17. The safety and efficacy of front-firing green-light laser endoscopic en bloc photoselective vapo-enucleation of non-muscle-invasive bladder cancer.

    Science.gov (United States)

    Cheng, Bo; Qiu, Xiaofu; Li, Huanhui; Yang, Guosheng

    2017-01-01

    Laser therapy provides an alternative option for treating non-muscle-invasive bladder cancer (NMIBC). However, the clinical evidence for potassium-titanyl-phosphate (KTP) laser en bloc resection is still limited. Here, we investigated the efficacy and safety of the 120-W front-firing KTP laser for the treatment of NMIBC. A total of 64 patients with NMIBC treated with either a 120-W front-firing KTP-photoselective vapo-enucleation of the bladder tumor (PVEBT, n=34) or transurethral resection of the bladder tumor (TURBT, n=30) were included. En bloc resection was applied to the patients in PVEBT group. There was no significant difference in rinsing time (P=0.292), indwelling catheter (P=0.080), pathologic type, and T stage (P=0.870) between the two groups. Compared with the TURBT group, patients treated with PVEBT had a shorter hospitalization stay (P=0.044), a shorter operation time (P=0.008), and a lower muscle miss rate (P=0.044). PVEBT is superior to TURBT in terms of the rate of 1-year recurrence (P=0.015) and tumor grade progression rate (P=0.019). The 120-W front-firing KTP laser en bloc enucleation technique is a safe and feasible procedure for treating patients with NMIBC. Further external validation in larger cohorts with a long follow-up period is warranted.

  18. Generation of shock fronts in the interaction of short pulses of intense laser light in supercritical plasma; Generacion de frentes de choque en la interaccion de pulsos cortos de luz laser intensa en plasmas supercriticos

    Energy Technology Data Exchange (ETDEWEB)

    Lopez V, V.E. [ITESST, 52650 Estado de Mexico (Mexico); Ondarza R, R. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    2004-07-01

    The investigation of the laser interaction with plasma has been carried out mainly in laboratories of Europe, Japan and United States during the last decades. This studies concern the propagation of intense light laser in a non homogeneous plasma, the radiation absorption and the generation of suprathermal electrons, among others. Numerical simulations made by Denavit, for radiation pulses for up of 10{sup 20} W/cm{sup 2} on solid targets, have allowed to observe the generation of ionic crash fronts with high propagation speeds. In this work it is expanded the study of this effect through algorithms of particles simulation. (Author)

  19. Activity patterns of Eurasian lynx are modulated by light regime and individual traits over a wide latitudinal range.

    Directory of Open Access Journals (Sweden)

    Marco Heurich

    Full Text Available The activity patterns of most terrestrial animals are regarded as being primarily influenced by light, although other factors, such as sexual cycle and climatic conditions, can modify the underlying patterns. However, most activity studies have been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network of studies conducted with identical methodology in different areas spanning latitudes from 49°7'N in central Europe to 70°00'N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day-night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPS-collars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most important prey.

  20. Activity patterns of Eurasian lynx are modulated by light regime and individual traits over a wide latitudinal range.

    Science.gov (United States)

    Heurich, Marco; Hilger, Anton; Küchenhoff, Helmut; Andrén, Henrik; Bufka, Luděk; Krofel, Miha; Mattisson, Jenny; Odden, John; Persson, Jens; Rauset, Geir R; Schmidt, Krzysztof; Linnell, John D C

    2014-01-01

    The activity patterns of most terrestrial animals are regarded as being primarily influenced by light, although other factors, such as sexual cycle and climatic conditions, can modify the underlying patterns. However, most activity studies have been limited to a single study area, which in turn limit the variability of light conditions and other factors. Here we considered a range of variables that might potentially influence the activity of a large carnivore, the Eurasian lynx, in a network of studies conducted with identical methodology in different areas spanning latitudes from 49°7'N in central Europe to 70°00'N in northern Scandinavia. The variables considered both light conditions, ranging from a day with a complete day-night cycle to polar night and polar day, as well as individual traits of the animals. We analysed activity data of 38 individual free-ranging lynx equipped with GPS-collars with acceleration sensors, covering more than 11,000 lynx days. Mixed linear additive models revealed that the lynx activity level was not influenced by the daily daylight duration and the activity pattern was bimodal, even during polar night and polar day. The duration of the active phase of the activity cycle varied with the widening and narrowing of the photoperiod. Activity varied significantly with moonlight. Among adults, males were more active than females, and subadult lynx were more active than adults. In polar regions, the amplitude of the lynx daily activity pattern was low, likely as a result of the polycyclic activity pattern of their main prey, reindeer. At lower latitudes, the basic lynx activity pattern peaked during twilight, corresponding to the crepuscular activity pattern of the main prey, roe deer. Our results indicated that the basic activity of lynx is independent of light conditions, but is modified by both individual traits and the activity pattern of the locally most important prey.

  1. Range and Richness of Vascular Land-Plants: The role of variable light (Invited)

    Science.gov (United States)

    Eagleson, P. S.

    2009-12-01

    Since the time of Darwin it has been recognized that with increasing latitude, the average continuous range of latitudes occupied by all the plant species found locally increases, while the number of different species found there (i.e. the local richness of species) decreases. General agreement has developed that climate is somehow responsible, but as recently as 1992 E.O. Wilson found the richness gradient still to be "...one of the great theoretical problems of evolutionary biology", and the 2006 Millenium Ecosystem Assessment found that "We lack a robust theoretical basis for linking ecological diversity to ecosystem dynamics...". In a "zeroth-order" approximation of reality, we posit here that incident SW radiation is the principal driver of these phenomena. We show that the species-specific intersection of the asymptotes of the photosynthetic-capacity curves of the C3 plants overwhelmingly predominant in the extra-tropics offer, at these latitudes, a unique state defining the Darwinian-optimum species (horizontal leaf-area index) for each local climate (average incident SW radiation). This provides a basis for a locally-linear transformation of the probability density function of observed local SW flux into the resulting probability density function of stable species and thence into the range of latitudes separating the same species when appearing in the extremes of this distribution. Further assuming the maximum number of stable local species to be the one-for-one result of separate germination-cum-species-supporting SW flux events, we model their local arrival as a stochastic process and count their annual number as an estimate of the local maximum richness. Range and richness are found here to be inversely related theoretically as was noted observationally by Rapoport (1975), and agreement of both theories with observations is found to be excellent at extra-tropical latitudes. [Currently in the publication process, this work will appear shortly as a

  2. The safety and efficacy of front-firing green-light laser endoscopic en bloc photoselective vapo-enucleation of non-muscle-invasive bladder cancer

    Directory of Open Access Journals (Sweden)

    Cheng B

    2017-08-01

    Full Text Available Bo Cheng,1,2 Xiaofu Qiu,1 Huanhui Li,1 Guosheng Yang1 1Department of Urology, Southern Medical University affiliated Guangdong Second Provincial General Hospital, Southern Medical University, Guangzhou, People’s Republic of China; 2Department of Urology, The Affiliated Hospital of Southwest Medical University, Luzhou, People’s Republic of China Purpose: Laser therapy provides an alternative option for treating non-muscle-invasive bladder cancer (NMIBC. However, the clinical evidence for potassium-titanyl-phosphate (KTP laser en bloc resection is still limited. Here, we investigated the efficacy and safety of the 120-W front-firing KTP laser for the treatment of NMIBC.Methods: A total of 64 patients with NMIBC treated with either a 120-W front-firing KTP-photoselective vapo-enucleation of the bladder tumor (PVEBT, n=34 or transurethral resection of the bladder tumor (TURBT, n=30 were included. En bloc resection was applied to the patients in PVEBT group.Results: There was no significant difference in rinsing time (P=0.292, indwelling catheter (P=0.080, pathologic type, and T stage (P=0.870 between the two groups. Compared with the TURBT group, patients treated with PVEBT had a shorter hospitalization stay (P=0.044, a shorter operation time (P=0.008, and a lower muscle miss rate (P=0.044. PVEBT is superior to TURBT in terms of the rate of 1-year recurrence (P=0.015 and tumor grade progression rate (P=0.019.Conclusion: The 120-W front-firing KTP laser en bloc enucleation technique is a safe and feasible procedure for treating patients with NMIBC. Further external validation in larger cohorts with a long follow-up period is warranted. Keywords: bladder cancer, transurethral resection, en bloc, laser surgery, recurrence

  3. Lighting

    Data.gov (United States)

    Federal Laboratory Consortium — Lighting Systems Test Facilities aid research that improves the energy efficiency of lighting systems. • Gonio-Photometer: Measures illuminance from each portion of...

  4. Light

    DEFF Research Database (Denmark)

    Prescott, N.B.; Kristensen, Helle Halkjær; Wathes, C.M.

    2004-01-01

    This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality......This chapter presents the effect of artificial light environments (light levels, colour, photoperiod and flicker) on the welfare of broilers in terms of vision, behaviour, lameness and mortality...

  5. Pulse front adaptive optics: a new method for control of ultrashort laser pulses.

    Science.gov (United States)

    Sun, Bangshan; Salter, Patrick S; Booth, Martin J

    2015-07-27

    Ultrafast lasers enable a wide range of physics research and the manipulation of short pulses is a critical part of the ultrafast tool kit. Current methods of laser pulse shaping are usually considered separately in either the spatial or the temporal domain, but laser pulses are complex entities existing in four dimensions, so full freedom of manipulation requires advanced forms of spatiotemporal control. We demonstrate through a combination of adaptable diffractive and reflective optical elements - a liquid crystal spatial light modulator (SLM) and a deformable mirror (DM) - decoupled spatial control over the pulse front (temporal group delay) and phase front of an ultra-short pulse was enabled. Pulse front modulation was confirmed through autocorrelation measurements. This new adaptive optics technique, for the first time enabling in principle arbitrary shaping of the pulse front, promises to offer a further level of control for ultrafast lasers.

  6. Absorbance detector for high-performance liquid chromatography based on light-emitting diodes for the deep-ultraviolet range.

    Science.gov (United States)

    Bomastyk, Benjamin; Petrovic, Igor; Hauser, Peter C

    2011-06-17

    A HPLC-detector has been designed which employs light-emitting diodes in the deep-UV-range below 300 nm as wavelength specific radiation sources and special UV-photodiodes for measuring the signal. A monochromator is therefore not needed. The design features a beam splitter and a reference photodiode, precision mechanics for adjustment of the light beams and electronics for stabilization of the LED-current. The processing of the photodiode currents is carried out with a high performance log-ratio amplifier which allows direct absorbance measurements. The optical and electronic performance of the detector was characterised and high precision over several absorbance units was obtained. Testing of analytical separation methods in isocratic as well as gradient modes employing UV-detection at 255 and 280 nm showed a very similar performance to a commercial photodiode-array detector used in the fixed wavelength mode in terms of linearity, precision and detection limits. The chief advantages of the new device are small size, low power consumption, and low cost. Copyright © 2011 Elsevier B.V. All rights reserved.

  7. A background light resistant TOF range finder with integrated PIN photodiode in 0.35μm CMOS

    Science.gov (United States)

    Davidovic, Milos; Seiter, Johannes; Hofbauer, Michael; Gaberl, Wolfgang; Zimmermann, Horst

    2013-04-01

    Within this work a single pixel Time-of-Flight (TOF) based range finder is presented. The sensor is fabricated in a 0.35 μm 1P4M CMOS process occupying an area of 45 × 60 μm2 at ~50% fill factor. It takes advantage of the integrated PIN photodiode, representing, to the best knowledge of the author, the first reported TOF device done in this technology with a PIN detector. The measurement results show a standard deviation of 1 cm for a total integration time of 2.2 ms and a received optical power of 10 nW. Furthermore, the maximal measured integration time per single phase step is slightly below 1 ms, being an improvement by the factor of 40 over the previous work using a similar approach. As proven with the measurements, the background light influence on the measured distance can be neglected even if the dc light is by the factor of 600 larger than the modulation signal.

  8. High efficiency AlGaInN-based light emitting diode in the 360-380 nm wavelength range

    Energy Technology Data Exchange (ETDEWEB)

    Sato, Hisao; Wang, Hong-Xing; Sato, Daisuke; Takaki, Ryohei; Wada, Naoki; Tanahashi, Tetsuya; Yamashita, Kenji; Kawano, Shunsuke; Mizobuchi, Takashi; Dempo, Akihiko; Morioka, Kenji; Kimura, Masahiro; Nohda, Suguru [Nitride Semiconductors Co., Ltd., 115-7 Itayajima, Akinokami, Seto-cho, Naruto, Tokushima 771-0360 (Japan); Sugahara, Tomoya [Satellite Venture Business Laboratory, The University of Tokushima (Japan); Sakai, Shiro [Department of Electrical and Electronic Engineering, The University of Tokushima, 2-1 Minami-josanjima, Tokushima 770-8506 (Japan)

    2003-11-01

    High performance LEDs emitting in the wavelength range 360-380 nm, are fabricated on sapphire substrates by one-time metalorganic chemical vapor deposition (MOCVD) without using epitaxial lateral overgrowth (ELO) or similar techniques. By improving layer structures and growth conditions, the output power of the LEDs was much improved. The light output power of the LEDs at an injection current of 20 mA is 3.2 mW, 2.5 mW and 1 mW at wavelengths of 378 nm, 373 nm and 363 nm, which correspond to an external quantum efficiency of 4.8%, 3.8% and 1.4%, respectively. (copyright 2003 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. MoonLIGHT: A USA-Italy lunar laser ranging retroreflector array for the 21st century

    Science.gov (United States)

    Martini, M.; Dell'Agnello, S.; Currie, D.; Delle Monache, G.; Vittori, R.; Chandler, J. F.; Cantone, C.; Boni, A.; Berardi, S.; Patrizi, G.; Maiello, M.; Garattini, M.; Lops, C.; March, R.; Bellettini, G.; Tauraso, R.; Intaglietta, N.; Tibuzzi, M.; Murphy, T. W.; Bianco, G.; Ciocci, E.

    2012-12-01

    Since the 1970s Lunar Laser Ranging (LLR) to the Apollo Cube Corner Retroreflector (CCR) arrays (developed by the University of Maryland, UMD) have supplied significant tests of General Relativity: possible changes in the gravitational constant, gravitational self-energy, weak equivalence principle, geodetic precession, inverse-square force-law. LLR has also provided significant information on the composition and origin of the Moon. This is the only Apollo experiment still in operation. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT (Moon Laser Instrumentation for General relativity High-accuracy Tests), in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single, large CCR (100 mm diameter) unaffected by librations. In particular, INFN-LNF built and is operating a new experimental apparatus (Satellite/lunar laser ranging Characterization Facility, SCF) and created a new industry-standard test procedure (SCF-Test) to characterize and model the detailed thermal behavior and the optical performance of CCRs in laboratory-simulated space conditions, for industrial and scientific applications. Our key experimental innovation is the concurrent measurement and modeling of the optical Far Field Diffraction Pattern (FFDP) and the temperature distribution of retroreflector payloads under thermal conditions produced with a solar simulator. The apparatus includes infrared cameras for non-invasive thermometry, thermal control and real-time payload movement to simulate satellite orientation on orbit with respect to solar illumination and laser interrogation beams. These capabilities provide: unique pre-launch performance validation of the space segment of LLR/SLR (Satellite Laser

  10. Front matter: Volume 10385

    Science.gov (United States)

    Assoufid, Lahsen; Ohashi, Haruhiko; Asundi, Anand K.

    2017-09-01

    This PDF file contains the front matter associated with SPIE Proceedings Volume 10385, including the Title Page, Copyright information, Table of Contents, Introduction, and Conference Committee listing.

  11. Shack-Hartmann wave front measurements in cortical tissue for deconvolution of large three-dimensional mosaic transmitted light brightfield micrographs.

    Science.gov (United States)

    Oberlaender, M; Broser, P J; Sakmann, B; Hippler, S

    2009-02-01

    We present a novel approach for deconvolution of 3D image stacks of cortical tissue taken by mosaic/optical-sectioning technology, using a transmitted light brightfield microscope. Mosaic/optical-sectioning offers the possibility of imaging large volumes (e.g. from cortical sections) on a millimetre scale at sub-micrometre resolution. However, a blurred contribution from out-of-focus light results in an image quality that usually prohibits 3D quantitative analysis. Such quantitative analysis is only possible after deblurring by deconvolution. The resulting image quality is strongly dependent on how accurate the point spread function used for deconvolution resembles the properties of the imaging system. Since direct measurement of the true point spread function is laborious and modelled point spread functions usually deviate from measured ones, we present a method of optimizing the microscope until it meets almost ideal imaging conditions. These conditions are validated by measuring the aberration function of the microscope and tissue using a Shack-Hartmann sensor. The analysis shows that cortical tissue from rat brains embedded in Mowiol and imaged by an oil-immersion objective can be regarded as having a homogeneous index of refraction. In addition, the amount of spherical aberration that is caused by the optics or the specimen is relatively low. Consequently the image formation is simplified to refraction between the embedding and immersion medium and to 3D diffraction at the finite entrance pupil of the objective. The resulting model point spread function is applied to the image stacks by linear or iterative deconvolution algorithms. For the presented dataset of large 3D images the linear approach proves to be superior. The linear deconvolution yields a significant improvement in signal-to-noise ratio and resolution. This novel approach allows a quantitative analysis of the cortical image stacks such as the reconstruction of biocytin-stained neuronal dendrites

  12. How Evapotranspiration And Deep Percolation Impact The Precipitation-Runoff Response, Aquifer Recharge, And Linked Nutrient-Water Cycling At The Subalpine Como Creek Drainage In The Colorado Front Range

    Science.gov (United States)

    Zeliff, M. M.; Williams, M. W.; Cowie, R. M.; Burns, S.

    2011-12-01

    Here we evaluate how evapotranspiration (ET) and deep percolation (DP) impact the precipitation-runoff response, aquifer recharge, and linked nutrient-water cycling at the 664-ha sub-alpine Como Creek drainage in the Colorado Front Range. ET is measured continuously using eddy covariance, soil moisture (SM) is measured using 2-m vertical sensor arrays, groundwater (GW) by a series of piezometers, and precipitation (P) is measured daily along with snow-water equivalent (SWE). From 2004 to 2009, annual P averaged 813 mm and ET averaged 590 mm, with ET thus representing 72.5% of annual P. Using multiple linear regression analysis, discharge (Q) was found to be modeled reasonably well with the independent variables of ET (p ground water system and subsequent precipitation does little to contribute to streamflow for the current year, but serves to offset ET, which may explain the decrease in Q with increasing P. Newly installed piezometers (12, at depths ranging from 5 to 30 m) provide evidence that this portion of the basin is largely a loosing reach during snowmelt, with GW in the piezometers increasing 5-7 m. After peak snowmelt however, the reach starts gaining again with piezometer levels dropping. Time series plots reveal a strong relationship between SWE and Q with larger SWE often resulting in larger Q. Thus, surface-groundwater interactions are tightly coupled during snowmelt, with snowmelt first replenishing the subsurface water deficit before contributing to discharge. The deepest two piezometers (18 and 29 m) were not showing any significant water level declines by early August 2011, suggesting that water loss to DP is a potential important component of the water balance in the Como Creek catchment. Wet precipitation chemistry from the National Atmospheric Deposition Program monitors in the basin show that atmospheric deposition of inorganic nitrogen has increased several-fold in the last 25 years. However, in contrast to higher-elevation catchments, which

  13. Absorbance detector for capillary electrophoresis based on light-emitting diodes and photodiodes for the deep-ultraviolet range.

    Science.gov (United States)

    Bui, Duy Anh; Hauser, Peter C

    2015-11-20

    A new absorbance detector for capillary electrophoresis featuring relatively high intensity light-emitting diodes as radiation sources and photodiodes for the deep-UV range was developed. The direct relationship of absorbance values and concentrations was obtained by emulating Lambert-Beer's law with the application of a beam splitter to obtain a reference signal and a log-ratio amplifier circuitry. The performance of the cell was investigated at 255 nm with the detection of sulfanilic, 4-nitrobenzoic, 4-hydroxybenzoic and 4-aminobenzoic acid and the indirect detection of acetate, propionate, butyrate and caproate using benzoate as the displacement dye molecule. Vanillic acid, L-tyrosine and DL-tryptophan as well as the sulfonamides sulfamerazine, sulfathiazole and sulfamethazine were determined at 280 nm. Good linearities over 3 orders of magnitude were obtained. The noise level recorded was as low as 50 μAU and the drift typically <200 μAU/5 min. Copyright © 2015 Elsevier B.V. All rights reserved.

  14. Light

    CERN Document Server

    Robertson, William C

    2003-01-01

    Why is left right and right left in the mirror? Baffled by the basics of reflection and refraction? Wondering just how the eye works? If you have trouble teaching concepts about light that you don t fully grasp yourself, get help from a book that s both scientifically accurate and entertaining with Light. By combining clear explanations, clever drawings, and activities that use easy-to-find materials, this book covers what science teachers and parents need to know to teach about light with confidence. It uses ray, wave, and particle models of light to explain the basics of reflection and refraction, optical instruments, polarization of light, and interference and diffraction. There s also an entire chapter on how the eye works. Each chapter ends with a Summary and Applications section that reinforces concepts with everyday examples. Whether you need a deeper understanding of how light bends or a good explanation of why the sky is blue, you ll find Light more illuminating and accessible than a college textbook...

  15. A wide area Bipolar Cascade Resonant Cavity Light Emitting Diode for a Hybrid Range-Intensity Sensor

    Science.gov (United States)

    Turner, Reginald J.

    Autonomous Ground Vehicles (AGV) will require high-speed, real-time three dimensional (3-D) image processing to navigate treacherous terrain in order to complete their assigned mission without a human in the loop. LIDAR scanners of the 3-D variety, provide the necessary area coverage for 3-D image processing, but lack the speed to deliver the collected data for real-time processing. A novel Hybrid Range-Intensity System (HRIS) has been proposed for imaging large swaths of area very rapidly. This system is comprised of two infrared cameras, an illumination source, a control and coordination system to position the cameras, and signal processing algorithms to extract the contour image of the scene. This dissertation focused on the development of an illuminator for the HRIS. This illuminator enables faster image rendering and reduces the potential of errors in return signal data, that could be generated from extremely rough terrain. Four major achievements resulted from this work, which advance the field of 3-D image acquisition. The first is that the TJ is an effective current spreading layer for LEDs with mesa width up to 140 mum and current densities of ˜ 1 x 106A/cm2. The TJ allows fabrication of an efficient illuminator, with required geometry for the HRIS to operate as a real-time 3-D imaging system. Secondly, a design for a Bipolar Cascade-Resonant Cavity Light Emitting Diode (BC-RCLED) has been accomplished, that will illuminate the FOV of the hybrid-ranged intensity system with a single sweep of the beam. This device is capable of producing ˜ 330 mW of output power. Additionally, from this work, key parameters for HRIS design were identified. Using a collection optic with a 15 cm diameter, an HRIS mounting height of 1.5 m, and a detector integration time of 330 msec, a SNR of 20 dB was achieved. Lastly, we demonstrated that the BC-RCLED designed for the HRIS can deliver sufficient energy to produce the required SNR. Also, through parametric analysis, we

  16. Perturbative High Harmonic Wave Front Control.

    Science.gov (United States)

    Li, Zhengyan; Brown, Graham; Ko, Dong Hyuk; Kong, Fanqi; Arissian, Ladan; Corkum, P B

    2017-01-20

    We pattern the wave front of a high harmonic beam by intersecting the intense driving laser pulse that generates the high harmonic with a weak control pulse. To illustrate the potential of wave-front control, we imprint a Fresnel zone plate pattern on a harmonic beam, causing the harmonics to focus and defocus. The quality of the focus that we achieve is measured using the spectral wave-front optical reconstruction by diffraction method. We will show that it is possible to enhance the peak intensity by orders of magnitude without a physical optical element in the path of the extreme ultraviolet (XUV) beam. Through perturbative wave-front control, XUV beams can be created with a flexibility approaching what technology allows for visible and infrared light.

  17. Airborne Light Detection and Ranging (LiDAR for Individual Tree Stem Location, Height, and Biomass Measurements

    Directory of Open Access Journals (Sweden)

    Michael G. Wing

    2011-11-01

    Full Text Available Light Detection and Ranging (LiDAR remote sensing has demonstrated potential in measuring forest biomass. We assessed the ability of LiDAR to accurately estimate forest total above ground biomass (TAGB on an individual stem basis in a conifer forest in the US Pacific Northwest region using three different computer software programs and compared results to field measurements. Software programs included FUSION, TreeVaW, and watershed segmentation. To assess the accuracy of LiDAR TAGB estimation, stem counts and heights were analyzed. Differences between actual tree locations and LiDAR-derived tree locations using FUSION, TreeVaW, and watershed segmentation were 2.05 m (SD 1.67, 2.19 m (SD 1.83, and 2.31 m (SD 1.94, respectively, in forested plots. Tree height differences from field measured heights for FUSION, TreeVaW, and watershed segmentation were −0.09 m (SD 2.43, 0.28 m (SD 1.86, and 0.22 m (2.45 in forested plots; and 0.56 m (SD 1.07 m, 0.28 m (SD 1.69 m, and 1.17 m (SD 0.68 m, respectively, in a plot containing young conifers. The TAGB comparisons included feature totals per plot, mean biomass per feature by plot, and total biomass by plot for each extraction method. Overall, LiDAR TAGB estimations resulted in FUSION and TreeVaW underestimating by 25 and 31% respectively, and watershed segmentation overestimating by approximately 10%. LiDAR TAGB underestimation occurred in 66% and overestimation occurred in 34% of the plot comparisons.

  18. Negative Ion Density Fronts

    Energy Technology Data Exchange (ETDEWEB)

    Igor Kaganovich

    2000-12-18

    Negative ions tend to stratify in electronegative plasmas with hot electrons (electron temperature Te much larger than ion temperature Ti, Te > Ti ). The boundary separating a plasma containing negative ions, and a plasma, without negative ions, is usually thin, so that the negative ion density falls rapidly to zero-forming a negative ion density front. We review theoretical, experimental and numerical results giving the spatio-temporal evolution of negative ion density fronts during plasma ignition, the steady state, and extinction (afterglow). During plasma ignition, negative ion fronts are the result of the break of smooth plasma density profiles during nonlinear convection. In a steady-state plasma, the fronts are boundary layers with steepening of ion density profiles due to nonlinear convection also. But during plasma extinction, the ion fronts are of a completely different nature. Negative ions diffuse freely in the plasma core (no convection), whereas the negative ion front propagates towards the chamber walls with a nearly constant velocity. The concept of fronts turns out to be very effective in analysis of plasma density profile evolution in strongly non-isothermal plasmas.

  19. Light

    CERN Document Server

    Ditchburn, R W

    1963-01-01

    This classic study, available for the first time in paperback, clearly demonstrates how quantum theory is a natural development of wave theory, and how these two theories, once thought to be irreconcilable, together comprise a single valid theory of light. Aimed at students with an intermediate-level knowledge of physics, the book first offers a historical introduction to the subject, then covers topics such as wave theory, interference, diffraction, Huygens' Principle, Fermat's Principle, and the accuracy of optical measurements. Additional topics include the velocity of light, relativistic o

  20. Lights illuminate surfaces superluminally

    Science.gov (United States)

    Nemiroff, Robert J.; Zhong, Qi; Lilleskov, Elias

    2016-07-01

    When a light bulb is turned on, light moves away from it at speed c, by definition. When light from this bulb illuminates a surface, however, this illumination front is not constrained to move at speed c. A simple proof is given that this illumination front always moves faster than c. Generalized, when any compact light source itself varies, this information spreads across all of the surfaces it illuminates at speeds faster than light.

  1. Realization of high-luminous-efficiency InGaN light-emitting diodes in the “green gap” range

    Science.gov (United States)

    Jiang, Yang; Li, Yangfeng; Li, Yueqiao; Deng, Zhen; Lu, Taiping; Ma, Ziguang; Zuo, Peng; Dai, Longgui; Wang, Lu; Jia, Haiqiang; Wang, Wenxin; Zhou, Junming; Liu, Wuming; Chen, Hong

    2015-01-01

    Light-emitting diodes (LEDs) in the wavelength region of 535–570 nm are still inefficient, which is known as the “green gap” problem. Light in this range causes maximum luminous sensation in the human eye and is therefore advantageous for many potential uses. Here, we demonstrate a high-brightness InGaN LED with a normal voltage in the “green gap” range based on hybrid multi-quantum wells (MQWs). A yellow-green LED device is successfully fabricated and has a dominant wavelength, light output power, luminous efficiency and forward voltage of 560 nm, 2.14 mW, 19.58 lm/W and 3.39 V, respectively. To investigate the light emitting mechanism, a comparative analysis of the hybrid MQW LED and a conventional LED is conducted. The results show a 2.4-fold enhancement of the 540-nm light output power at a 20-mA injection current by the new structure due to the stronger localization effect, and such enhancement becomes larger at longer wavelengths. Our experimental data suggest that the hybrid MQW structure can effectively push the efficient InGaN LED emission toward longer wavelengths, connecting to the lower limit of the AlGaInP LEDs’ spectral range, thus enabling completion of the LED product line covering the entire visible spectrum with sufficient luminous efficacy. PMID:26039353

  2. Topographic data of selected areas along the Alabama River near Montgomery, Alabama, collected using mobile terrestrial light detection and ranging (T-LiDAR) technology

    Science.gov (United States)

    Kimbrow, D.R.

    2014-01-01

    Topographic data at selected areas within the Alabama River flood plain near Montgomery, Alabama, were collected using a truck-mounted mobile terrestrial light detection and ranging system. These data were collected for inclusion in a flood inundation model developed by the National Weather Service in Birmingham, Alabama. Data are presented as ArcGIS point shapefiles with the extension .shp.

  3. Comparison of multialkali and GaAs photocathode detectors for Joint European Torus edge light detection and ranging Thomson scattering profiles

    NARCIS (Netherlands)

    Kempenaars, M.; Nielsen, P.; Pasqualotto, R.; Gowers, C.; Beurskens, M.

    2004-01-01

    The Joint European Torus (JET) tokamak has two light detection and ranging (LIDAR) Thomson scattering systems, one for the core and one dedicated to the edge T-e and n(e) profiles. The LIDAR scheme is unique to JET and is envisaged for use on ITER. The system's spatial resolution is defined by

  4. Could natural selection change the geographic range limits of light brown apple moth (Lepidoptera, Tortricidae) in North America?

    Science.gov (United States)

    Amy C. Morey; Robert C. Venette; William D. Hutchison

    2013-01-01

    We artificially selected for increased freeze tolerance in the invasive light brown apple moth. Our results suggest that, by not accounting for adaptation to cold, current models of potential geographic distributions could underestimate the areas at risk of exposure to this species.

  5. Photoinduced catalytic adsorption of model contaminants on Bi/Cu pillared montmorillonite in the visible light range

    Science.gov (United States)

    Montmorillonite K10 clay was pillared with BiCl3 and Cu(NO3)2 to extend its applicability as catalytic adsorbent to degrade aqueous solution of anionic azo-dye Methyl Orange (MO) in the presence of visible light irradiation. The preparation of Bi/Cu-montmorillonite utilized benig...

  6. Extension of the modal wave-front reconstruction algorithm to non-uniform illumination.

    Science.gov (United States)

    Ma, Xiaoyu; Mu, Jie; Rao, ChangHui; Yang, Jinsheng; Rao, XueJun; Tian, Yu

    2014-06-30

    Attempts are made to eliminate the effects of non-uniform illumination on the precision of wave-front measurement. To achieve this, the relationship between the wave-front slope at a single sub-aperture and the distributions of the phase and light intensity of the wave-front were first analyzed to obtain the relevant theoretical formulae. Then, based on the principle of modal wave-front reconstruction, the influence of the light intensity distribution on the wave-front slope is introduced into the calculation of the reconstruction matrix. Experiments were conducted to prove that the corrected modal wave-front reconstruction algorithm improved the accuracy of wave-front reconstruction. Moreover, the correction is conducive to high-precision wave-front measurement using a Hartmann wave-front sensor in the presence of non-uniform illumination.

  7. FRET-Mediated Long-Range Wavelength Transformation by Photoconvertible Fluorescent Proteins as an Efficient Mechanism to Generate Orange-Red Light in Symbiotic Deep Water Corals

    Science.gov (United States)

    Bollati, Elena; Plimmer, Daniel; D’Angelo, Cecilia; Wiedenmann, Jörg

    2017-01-01

    Photoconvertible fluorescent proteins (pcRFPs) are a group of fluorophores that undergo an irreversible green-to-red shift in emission colour upon irradiation with near-ultraviolet (near-UV) light. Despite their wide application in biotechnology, the high-level expression of pcRFPs in mesophotic and depth-generalist coral species currently lacks a biological explanation. Additionally, reduced penetration of near-UV wavelengths in water poses the question whether light-driven photoconversion is relevant in the mesophotic zone, or whether a different mechanism is involved in the post-translational pigment modification in vivo. Here, we show in a long-term mesocosm experiment that photoconversion in vivo is entirely dependent on near-UV wavelengths. However, a near-UV intensity equivalent to the mesophotic underwater light field at 80 m depth is sufficient to drive the process in vitro, suggesting that photoconversion can occur near the lower distribution limits of these corals. Furthermore, live coral colonies showed evidence of efficient Förster Resonance Energy Transfer (FRET). Our simulated mesophotic light field maintained the pcRFP pool in a partially photoconverted state in vivo, maximising intra-tetrameric FRET and creating a long-range wavelength conversion system with higher quantum yield than other native RFPs. We hypothesise that efficient conversion of blue wavelengths, abundant at depth, into orange-red light could constitute an adaptation of corals to life in light-limited environments. PMID:28677653

  8. FRET-Mediated Long-Range Wavelength Transformation by Photoconvertible Fluorescent Proteins as an Efficient Mechanism to Generate Orange-Red Light in Symbiotic Deep Water Corals.

    Science.gov (United States)

    Bollati, Elena; Plimmer, Daniel; D'Angelo, Cecilia; Wiedenmann, Jörg

    2017-07-04

    Photoconvertible fluorescent proteins (pcRFPs) are a group of fluorophores that undergo an irreversible green-to-red shift in emission colour upon irradiation with near-ultraviolet (near-UV) light. Despite their wide application in biotechnology, the high-level expression of pcRFPs in mesophotic and depth-generalist coral species currently lacks a biological explanation. Additionally, reduced penetration of near-UV wavelengths in water poses the question whether light-driven photoconversion is relevant in the mesophotic zone, or whether a different mechanism is involved in the post-translational pigment modification in vivo. Here, we show in a long-term mesocosm experiment that photoconversion in vivo is entirely dependent on near-UV wavelengths. However, a near-UV intensity equivalent to the mesophotic underwater light field at 80 m depth is sufficient to drive the process in vitro, suggesting that photoconversion can occur near the lower distribution limits of these corals. Furthermore, live coral colonies showed evidence of efficient Förster Resonance Energy Transfer (FRET). Our simulated mesophotic light field maintained the pcRFP pool in a partially photoconverted state in vivo, maximising intra-tetrameric FRET and creating a long-range wavelength conversion system with higher quantum yield than other native RFPs. We hypothesise that efficient conversion of blue wavelengths, abundant at depth, into orange-red light could constitute an adaptation of corals to life in light-limited environments.

  9. Optimal back-to-front airplane boarding.

    Science.gov (United States)

    Bachmat, Eitan; Khachaturov, Vassilii; Kuperman, Ran

    2013-06-01

    The problem of finding an optimal back-to-front airplane boarding policy is explored, using a mathematical model that is related to the 1+1 polynuclear growth model with concave boundary conditions and to causal sets in gravity. We study all airplane configurations and boarding group sizes. Optimal boarding policies for various airplane configurations are presented. Detailed calculations are provided along with simulations that support the main conclusions of the theory. We show that the effectiveness of back-to-front policies undergoes a phase transition when passing from lightly congested airplanes to heavily congested airplanes. The phase transition also affects the nature of the optimal or near-optimal policies. Under what we consider to be realistic conditions, optimal back-to-front policies lead to a modest 8-12% improvement in boarding time over random (no policy) boarding, using two boarding groups. Having more than two groups is not effective.

  10. Generalizing the flash technique in the front-face configuration to measure the thermal diffusivity of semitransparent solids

    Energy Technology Data Exchange (ETDEWEB)

    Pech-May, Nelson Wilbur [Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería, Universidad del País Vasco UPV/EHU, Alameda Urquijo s/n, 48013 Bilbao (Spain); Department of Applied Physics, CINVESTAV Unidad Mérida, carretera Antigua a Progreso km6, A.P. 73 Cordemex, Mérida Yucatán 97310, México (Mexico); Mendioroz, Arantza; Salazar, Agustín, E-mail: agustin.salazar@ehu.es [Departamento de Física Aplicada I, Escuela Técnica Superior de Ingeniería, Universidad del País Vasco UPV/EHU, Alameda Urquijo s/n, 48013 Bilbao (Spain)

    2014-10-15

    In this work, we have extended the front-face flash method to retrieve simultaneously the thermal diffusivity and the optical absorption coefficient of semitransparent plates. A complete theoretical model that allows calculating the front surface temperature rise of the sample has been developed. It takes into consideration additional effects, such as multiple reflections of the heating light beam inside the sample, heat losses by convection and radiation, transparency of the sample to infrared wavelengths, and heating pulse duration. Measurements performed on calibrated solids, covering a wide range of absorption coefficients (from transparent to opaque) and thermal diffusivities, validate the proposed method.

  11. Potential dynamic range in a scheme of the acousto-optical spectrometer providing light beam apodization for a large-aperture crystalline cell with linear acoustic losses

    Science.gov (United States)

    Shcherbakov, Alexandre S.; Luna Castellanos, Abraham; Tepichin Rodriguez, Eduardo; Balderas Mata, Sandra E.

    2008-02-01

    We develop our previous considerations for one of the most important problems related to optimizing the performance data of a new acousto-optical spectrometer for the analysis of radio-astronomical signals. The main attention is paid to estimating the side lobes of light distributions inherent in an individual resolvable spot in the output Fourier plane, governing the dynamic range of that spectrometer. At first, we analyze the Akhieser mechanism responsible for linear attenuation of both longitudinal and shear elastic waves in isotropic solid states. Similar analysis can be directly applied to crystalline materials as well in all the cases of passing elastic wave along the acoustic axis in crystals. Then, we estimate the influence of the acoustic attenuation along a large-aperture acousto-optical cells operating in a one- and two-phonon light scattering regimes. In so doing, the optimal operating points are discussed for both these regimes. Finally, the combined effect of the acoustic attenuation and the incident light beam apodization is studied from the points of view of optimizing the levels of side lobes and minima in light distribution of an individual resolvable spot in focal plane of the integrating lens and, consequently, estimating potential limitations of the dynamic range.

  12. Range-Gated LADAR Coherent Imaging Using Parametric Up-Conversion of IR and NIR Light for Imaging with a Visible-Range Fast-Shuttered Intensified Digital CCD Camera

    Energy Technology Data Exchange (ETDEWEB)

    YATES,GEORGE J.; MCDONALD,THOMAS E. JR.; BLISS,DAVID E.; CAMERON,STEWART M.; ZUTAVERN,FRED J.

    2000-12-20

    Research is presented on infrared (IR) and near infrared (NIR) sensitive sensor technologies for use in a high speed shuttered/intensified digital video camera system for range-gated imaging at ''eye-safe'' wavelengths in the region of 1.5 microns. The study is based upon nonlinear crystals used for second harmonic generation (SHG) in optical parametric oscillators (OPOS) for conversion of NIR and IR laser light to visible range light for detection with generic S-20 photocathodes. The intensifiers are ''stripline'' geometry 18-mm diameter microchannel plate intensifiers (MCPIIS), designed by Los Alamos National Laboratory and manufactured by Philips Photonics. The MCPIIS are designed for fast optical shattering with exposures in the 100-200 ps range, and are coupled to a fast readout CCD camera. Conversion efficiency and resolution for the wavelength conversion process are reported. Experimental set-ups for the wavelength shifting and the optical configurations for producing and transporting laser reflectance images are discussed.

  13. Erosion monitoring along the Coosa River below Logan Martin Dam near Vincent, Alabama, using terrestrial light detection and ranging (T-LiDAR) technology

    Science.gov (United States)

    Kimbrow, Dustin R.; Lee, Kathryn G.

    2013-01-01

    Alabama Power operates a series of dams on the Coosa River in east central Alabama. These dams form six reservoirs that provide power generation, flood control, recreation, economic opportunity, and fish and wildlife habitats to the region. The Logan Martin Reservoir is located approximately 45 kilometers east of Birmingham and borders Saint Clair and Talladega Counties. Discharges below the reservoir are controlled by power generation at Logan Martin Dam, and there has been an ongoing concern about the stability of the streambanks downstream of the dam. The U.S. Geological Survey, in cooperation with Alabama Power conducted a scientific investigation of the geomorphic conditions of a 115-meter length of streambank along the Coosa River by using tripod-mounted terrestrial light detection and ranging technology. Two surveys were conducted before and after the winter flood season of 2010 to determine the extent and magnitude of geomorphic change. A comparison of the terrestrial light detection and ranging datasets indicated that approximately 40 cubic meters of material had been eroded from the upstream section of the study area. The terrestrial light detection and ranging data included in this report consist of electronic point cloud files containing several million georeferenced data points, as well as a surface model measuring changes between scans.

  14. Tropical species at the northern limit of their range: composition and distribution in Bermuda's benthic habitats in relation to depth and light availability.

    Science.gov (United States)

    Manuel, Sarah A; Coates, Kathryn A; Kenworthy, W Judson; Fourqurean, James W

    2013-08-01

    Surveys were undertaken on the shallow Bermuda marine platform between 2006 and 2008 to provide a baseline of the distribution, condition and environmental characteristics of benthic communities. Bermuda is located in temperate latitudes but coral reefs, tropical seagrasses and calcareous green algae are common in the shallow waters of the platform. The dominant organisms of these communities are all living at or near their northern latitudinal range limits in the Atlantic Ocean. Among the major benthic autotrophs surveyed, seagrasses were most restricted by light availability. We found that the relatively slow-growing and long-lived seagrass Thalassia testudinum is restricted to habitats with much higher light availability than in the tropical locations where this species is commonly found. In contrast, the faster growing tropical seagrasses in Bermuda, Syringodium filiforme, Halodule sp. and Halophila decipiens, had similar ecological compensation depths (ECD) as in tropical locations. Increasing sea surface temperatures, concomitant with global climate change, may either drive or allow the poleward extensions of the ranges of such tropical species. However, due to latitudinal light limitations at least one abundant and common tropical autotroph, T. testudinum, is able to occupy only shallower depths at the more temperate latitudes of Bermuda. We hypothesize that the poleward shift of seagrass species ranges would be accompanied by restrictions to even shallower depths of T. testudinum and by very different seagrass community structures than in tropical locations. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Microstructure, a limiting parameter for determining the engineering range of compositions for light alloys: The Al-Cu-Si system

    Energy Technology Data Exchange (ETDEWEB)

    Plaza, D.; Pero-Sanz, J.A. [Univ. Politecnica, Madrid (Spain); Asensio, J.; Verdeja, J.I. [Univ. de Oviedo (Spain)

    1998-03-01

    Twelve as-cast alloys of the Al-Cu-Si ternary system were investigated. In all the cases, the microstructural phases observed were: {alpha} solid solution of Cu and Si in Al, CuAl{sub 2} ({theta} phase), and silicon crystals. The morphology and distribution of the {theta} and Si brittle constituents limit the percentages of Cu and Si added in the composition ranges of these commercial alloys.

  16. Dynamics of curved fronts

    CERN Document Server

    Pelce, Pierre

    1989-01-01

    In recent years, much progress has been made in the understanding of interface dynamics of various systems: hydrodynamics, crystal growth, chemical reactions, and combustion. Dynamics of Curved Fronts is an important contribution to this field and will be an indispensable reference work for researchers and graduate students in physics, applied mathematics, and chemical engineering. The book consist of a 100 page introduction by the editor and 33 seminal articles from various disciplines.

  17. Reduction of patulin in apple juice products by UV light of different wavelengths in the UVC range.

    Science.gov (United States)

    Zhu, Yan; Koutchma, Tatiana; Warriner, Keith; Zhou, Ting

    2014-06-01

    This study evaluated three UVC wavelengths (222, 254, and 282 nm) to degrade patulin introduced into apple juice or apple cider. The average UV fluences of 19.6, 84.3, 55.0, and 36.6 mJ·cm(-2) achieved through exposure to UV lamps at 222-, 254-, and 282-nm wavelengths and the combination of these wavelengths, respectively, resulted in 90% reduction of patulin in apple juice. Therefore, the order of efficiency of the three wavelength lamps was as follows: far UVC (222 nm) > far UVC plus (282 nm) > UVC (254 nm). In terms of color, treatment of apple juice with 222 nm resulted in an increase in the L* (lightness) value but decreases in a* (redness) and b* (yellowness) values, although the changes were insignificantly different from the values for nontreated controls based on a sensory evaluation. The ascorbic acid loss in juice treated at 222 nm to support 90% reduction of patulin was 36.5%, compared with ascorbic acid losses of 45.3 and 36.1% in samples treated at 254 and 282 nm, respectively. The current work demonstrated that the 222-nm wavelength possesses the highest efficiency for patulin reduction in apple juice when compared with the reductions by 254 and 282 nm, with no benefit gained from using a combination of wavelengths.

  18. Generation of shock fronts in the interaction of the short pulses of intense laser light in supercritical plasma; Generacion de frentes de choque en la interaccion de pulsos cortos de luz laser intensa en plasmas supercriticos

    Energy Technology Data Exchange (ETDEWEB)

    Lopez V, V.E

    2004-07-01

    The plasma is the state of the matter but diffused in the nature. The sun and the stars big heaps of hot plasma can be considered. The external surface of the terrestrial atmosphere this recovered by a layer of plasma. All gassy discharge (lightning spark arch etc.) this related with the formation of plasma. This way, 99 percent of our environment this formed almost of plasma. It is denominated plasma to the ionized gas in the one which all or most of the atoms have lost one or several of the electrons that belonged him, becoming positive ions and free electrons. In the plasma certain physical characteristics exist as for their behavior like they are the collective movements the quasi neutrality, the Debye length, the uncertainty etc. All these behaviors make that the study of the plasma is complex. For this they exist technical of numeric simulation joined to the technological advance of big computers of more capacity and prosecution speed. The simulation techniques of particles are those where a numeric code is built based on a model or theory of a system that it is wanted to investigate. This way through the simulation the results are compared with those theoretical predictions based on an analytic model. The applications of the physics of the plasma are multiple however we focus ourselves in the interaction laser-plasma. Both finish decades of investigation in the interaction of lasers with plasma they have been carried out in laboratories of Europe, Japan, United States. This studies concern the propagation of intense light laser in dense plasma homogeneous, the radiation absorption in cold plasma and problems related with the generation of suprathermal electrons among others. Other areas of the physics of the plasma-laser interaction that it has been considerable attention is the broadly well-known field as parametric uncertainties induced instabilities by the light and that they include the dispersions for example stimulated Raman and Brillouin being able to

  19. [The dangers of blue light: True story!].

    Science.gov (United States)

    Renard, G; Leid, J

    2016-05-01

    The dangers of the blue light are the object of numerous publications, for both the scientific community and the general public. The new prolific development of light sources emitting potentially toxic blue light (415-455nm) ranges from LED (Light Emitting Diodes) lamps for interior lighting to television screens, computers, digital tablets and smartphones using OLED (Organic Light Emitting Diode) or AMOLED (Active-Matrix Organic Light Emitting Diode) technology. First we will review some technical terms and the main characteristics of light perceived by the human eye. Then we will discuss scientific proof of the toxicity of blue light to the eye, which may cause cataract or macular degeneration. Analysis of the light spectra of several light sources, from natural light to LED lamps, will allow us to specify even better the dangers related to each light source. LED lamps, whether used as components for interior lighting or screens, are of concern if they are used for extended viewing times and at short distance. While we can protect ourselves from natural blue light by wearing colored glasses which filter out, on both front and back surfaces, the toxic wavelengths, it is more difficult to protect oneself from LED lamps in internal lighting, the use of which should be restricted to "white warmth" lamps (2700K). As far as OLED or AMOLED screens are concerned, the only effective protection consists of using them occasionally and only for a short period of time. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  20. Three-body bound states with zero-range interaction in the Bethe-Salpeter approach

    Science.gov (United States)

    Ydrefors, E.; Alvarenga Nogueira, J. H.; Gigante, V.; Frederico, T.; Karmanov, V. A.

    2017-07-01

    The Bethe-Salpeter equation for three bosons with zero-range interaction is solved for the first time. For comparison the light-front equation is also solved. The input is the two-body scattering length and the outputs are the three-body binding energies, Bethe-Salpeter amplitudes and light-front wave functions. Three different regimes are analyzed: (i) For weak enough two-body interaction the three-body system is unbound. (ii) For stronger two-body interaction a three-body bound state appears. It provides an interesting example of a deeply bound Borromean system. (iii) For even stronger two-body interaction this state becomes unphysical with a negative mass squared. However, another physical (excited) state appears, found previously in light-front calculations. The Bethe-Salpeter approach implicitly incorporates three-body forces of relativistic origin, which are attractive and increase the binding energy.

  1. On Front Slope Stability of Berm Breakwaters

    DEFF Research Database (Denmark)

    Burcharth, Hans F.

    2013-01-01

    The short communication presents application of the conventional Van der Meer stability formula for low-crested breakwaters for the prediction of front slope erosion of statically stable berm breakwaters with relatively high berms. The method is verified (Burcharth, 2008) by comparison...... test results including tests presented in Sigurdarson and Van der Meer (2011) are discussed. A proposal is presented for performance of new model tests with the purpose of developing more accurate formulae for the prediction of front slope erosion as a function of front slope, relative berm height......, relative berm width, method of armour stone placement, and hydraulic parameters. The formulae should cover the structure range from statically stable berm breakwaters to conventional double layer armoured breakwaters....

  2. Stationary flow near fronts

    Directory of Open Access Journals (Sweden)

    Reinhold Steinacker

    2016-12-01

    Full Text Available In 1906, the Austrian scientist Max Margules published a paper on temperature stratification in resting and non-accelerated moving air. The paper derives conditions for stationary slopes of air mass boundaries and was an important forerunner of frontal theories. Its formulation of relations between changes in density and geostrophic wind across the front is basically a discrete version of the thermal wind balance equation. The paper was highly influential and is still being cited to the present day. This paper accompanies an English translation of Margules’ seminal paper. We conclude here our “Classic Papers” series of the Meteorologische Zeitschrift.

  3. Nonvariational mechanism of front propagation: Theory and experiments.

    Science.gov (United States)

    Alvarez-Socorro, A J; Clerc, M G; González-Cortés, G; Wilson, M

    2017-01-01

    Multistable systems exhibit a rich front dynamics between equilibria. In one-dimensional scalar gradient systems, the spread of the fronts is proportional to the energy difference between equilibria. Fronts spreading proportionally to the energetic difference between equilibria is a characteristic of one-dimensional scalar gradient systems. Based on a simple nonvariational bistable model, we show analytically and numerically that the direction and speed of front propagation is led by nonvariational dynamics. We provide experimental evidence of nonvariational front propagation between different molecular orientations in a quasi-one-dimensional liquid-crystal light valve subjected to optical feedback. Free diffraction length allows us to control the variational or nonvariational nature of this system. Numerical simulations of the phenomenological model have quite good agreement with experimental observations.

  4. Climate change and Greenland White-fronted Geese Anser albifrons flavirostris: shifts in distribution and advancement in spring departure times at Wexford versus elsewhere in the winter range

    DEFF Research Database (Denmark)

    Fox, Anthony David; Merne, Oscar J; Walsh, Alyn J.

    2012-01-01

    in migration timing. The more rapid advancement of spring migration at Wexford compared to elsewhere in the range and the retention of wintering geese there in contrast to declining trends amongst the population as a whole suggest that local management of the food resource at Wexford may be responsible...

  5. Convection induced by thermal gradients on thin reaction fronts

    Science.gov (United States)

    Ruelas Paredes, David R. A.; Vasquez, Desiderio A.

    2017-09-01

    We present a thin front model for the propagation of chemical reaction fronts in liquids inside a Hele-Shaw cell or porous media. In this model we take into account density gradients due to thermal and compositional changes across a thin interface. The front separating reacted from unreacted fluids evolves following an eikonal relation between the normal speed and the curvature. We carry out a linear stability analysis of convectionless flat fronts confined in a two-dimensional rectangular domain. We find that all fronts are stable to perturbations of short wavelength, but they become unstable for some wavelengths depending on the values of compositional and thermal gradients. If the effects of these gradients oppose each other, we observe a range of wavelengths that make the flat front unstable. Numerical solutions of the nonlinear model show curved fronts of steady shape with convection propagating faster than flat fronts. Exothermic fronts increase the temperature of the fluid as they propagate through the domain. This increment in temperature decreases with increasing speed.

  6. Breaks in Pavement and Pipes as Indicators of Range-Front Faulting Resulting from the 1989 Loma Prieta Earthquake near the Southwest Margin of the Santa Clara Valley, California

    Science.gov (United States)

    Schmidt, Kevin M.; Ellen, Stephen D.; Haugerud, Ralph A.; Peterson, David M.; Phelps, Geoffery A.

    1995-01-01

    Damage to pavement and near-surface utility pipes, caused by the October 17, 1989, Loma Prieta earthquake, provide indicators for ground deformation in a 663 km2 area near the southwest margin of the Santa Clara Valley, California. The spatial distribution of 1284 sites of such damage documents the extent and distribution of detectable ground deformation. Damage was concentrated in four zones, three of which are near previously mapped faults. The zone through Los Gatos showed the highest concentration of damage, as well as evidence for pre- and post-earthquake deformation. Damage along the foot of the Santa Cruz Mountains reflected shortening that is consistent with movement along reverse faults in the region and with the hypothesis that tectonic strain is distributed widely across numerous faults in the California Coast Ranges.

  7. Direct Writing with Tilted-Front Femtosecond Pulses.

    Science.gov (United States)

    Patel, Aabid; Svirko, Yuri; Durfee, Charles; Kazansky, Peter G

    2017-10-10

    Shaping light fields in both space and time provides new degrees of freedom to manipulate light-matter interaction on the ultrafast timescale. Through this exploitation of the light field, a greater appreciation of spatio-temporal couplings in focusing has been gained, shedding light on previously unexplored parameters of the femtosecond light pulse, including pulse front tilt and wavefront rotation. Here, we directly investigate the effect of major spatio-temporal couplings on light-matter interaction and reveal unambiguously that in transparent media, pulse front tilt gives rise to the directional asymmetry of the ultrafast laser writing. We demonstrate that the laser pulse with a tilted intensity front deposits energy more efficiently when writing along the tilt than when writing against, producing either an isotropic damage-like or a birefringent nanograting structure. The directional asymmetry in the ultrafast laser writing is qualitatively described in terms of the interaction of a void trapped within the focal volume by the gradient force from the tilted intensity front and the thermocapillary force caused by the gradient of temperature. The observed instantaneous transition from the damage-like to nanograting modification after a finite writing length in a transparent dielectric is phenomenologically described in terms of the first-order phase transition.

  8. Probing ultra-fast processes with high dynamic range at 4th-generation light sources: Arrival time and intensity binning at unprecedented repetition rates

    Directory of Open Access Journals (Sweden)

    S. Kovalev

    2017-03-01

    Full Text Available Understanding dynamics on ultrafast timescales enables unique and new insights into important processes in the materials and life sciences. In this respect, the fundamental pump-probe approach based on ultra-short photon pulses aims at the creation of stroboscopic movies. Performing such experiments at one of the many recently established accelerator-based 4th-generation light sources such as free-electron lasers or superradiant THz sources allows an enormous widening of the accessible parameter space for the excitation and/or probing light pulses. Compared to table-top devices, critical issues of this type of experiment are fluctuations of the timing between the accelerator and external laser systems and intensity instabilities of the accelerator-based photon sources. Existing solutions have so far been only demonstrated at low repetition rates and/or achieved a limited dynamic range in comparison to table-top experiments, while the 4th generation of accelerator-based light sources is based on superconducting radio-frequency technology, which enables operation at MHz or even GHz repetition rates. In this article, we present the successful demonstration of ultra-fast accelerator-laser pump-probe experiments performed at an unprecedentedly high repetition rate in the few-hundred-kHz regime and with a currently achievable optimal time resolution of 13 fs (rms. Our scheme, based on the pulse-resolved detection of multiple beam parameters relevant for the experiment, allows us to achieve an excellent sensitivity in real-world ultra-fast experiments, as demonstrated for the example of THz-field-driven coherent spin precession.

  9. Long Range Surface Plasmon Resonance Based Taper Fiber Optic Sensor with Enhanced Sensitivity using Au Nano-Layer through Radially Polarized Light

    Science.gov (United States)

    Chaurasia, Deepak; Goswami, Nabamita; Saha, Ardhendu

    2017-08-01

    A new theoretical approach towards the sensitivity enhancement of tapered fiber optic sensor based on the long range surface plasmon (LRSP) resonance technique in Teflonmetal coated tapered fiber structure using radially polarized is proposed, designed and simulated within Kretschmann-Raether geometry. The configuration comprising a fiber core coated with 690 nm and 70 nm thin Teflon layer and Au layer respectively where the uniform taper waist having diameter 330 µm and 350 µm with taper ratio of 1.7 (NA: 0.25, 10 mm long waist region) and a sensing layer having varying refractive index from 1.333 to 1.353. With the increase in refractive index the observed results indicates a 1.7 times better sensitive tapered fiber sensor as compared to the existing LRSP based fibre optic sensors using intensity interrogation technique. To the best of our knowledge several articles have been devoted in the field of LRSP based fibre optic sensor with p-polarized light whereas no such article has yet been reported with Teflonused as a dielectric between metal coated taper fiber optic sensors using radially polarized light with better sensitivity. Here sensitivity also analysed w.r.t wavelength interrogation technique where the sensitivity enhancement is about 1.7 times than the existing fiber optic sensors.

  10. A novel wide range, real-time neutron fluence monitor based on commercial off the shelf gallium arsenide light emitting diodes

    Science.gov (United States)

    Mukherjee, B.; Hentschel, R.; Lambert, J.; Deya, W.; Farr, J.

    2011-10-01

    Displacement damage produced by high-energy neutrons in gallium arsenide (GaAs) light emitting diodes (LED) results in the reduction of light output. Based on this principle we have developed a simple, cost effective, neutron detector using commercial off the shelf (COTS) GaAs-LED for the assessment of neutron fluence and KERMA at critical locations in the vicinity of the 230 MeV proton therapy cyclotron operated by Westdeutsches Protonentherapiezentrum Essen (WPE). The LED detector response (mV) was found to be linear within the neutron fluence range of 3.0×10 8-1.0×10 11 neutron cm -2. The response of the LED detector was proportional to neutron induced displacement damage in LED; hence, by using the differential KERMA coefficient of neutrons in GaAs, we have rescaled the calibration curve for two mono-energetic sources, i.e. 1 MeV neutrons and 14 MeV neutrons generated by D+T fusion reaction. In this paper we present the principle of the real-time GaAs-LED based neutron fluence monitor as mentioned above. The device was calibrated using fast neutrons produced by bombarding a thick beryllium target with 14 MeV deuterons from a TCC CV 28 medical cyclotron of the Strahlenklinik University Hospital Essen.

  11. Forest canopy water fluxes can be estimated using canopy structure metrics derived from airborne light detection and ranging (LiDAR)

    DEFF Research Database (Denmark)

    Schumacher, Johannes; Christiansen, Jesper Riis

    2015-01-01

    Forests contribute to improve water quality, affect drinking water resources, and therefore influence water supply on a regional level. The forest canopy structure affects the retention of precipitation (Pr) in the canopy and hence the amount of water transferred to the forest floor termed canopy...... throughfall (TF). We investigated the possibilities of estimating TF based on bulk Pr and canopy structure estimated from airborne light detection and ranging (LiDAR) data. Bulk Pr and TF fluxes combined with airborne LiDAR data from 11 locations representing the most common forest types (mono......-species broadleaf/coniferous and mixed forests) in Denmark were used to develop empirical models to estimate TF on a monthly, seasonal, and annual basis. This new approach offers the opportunity to greatly improve predictions of TF on catchment wide scales. Overall, results show that TF can be estimated by Pr...

  12. QUENCH FRONT PROPAGATION IN THE ANNULAR CHANNEL

    Directory of Open Access Journals (Sweden)

    Jan Stepanek

    2016-12-01

    Full Text Available Understanding the quench front propagation during bottom core reflooding is crucial for the effective cooling during the LOCA accident. The results presented in this paper were obtained on an experimental loop with an annular test section. The test section consists of a vertical electrically heated stainless steel tube with outer diameter 9 mm and length of 1.7 m. The heated tube is placed inside a glass tube with the inner diameter 14.5 mm. Water mass flux during the reflooding is in the range from 100 kg.m−2.s−1 up to 140 kg.m−2.s−1 and the initial wall temperature of the stainless steel tube is in the range from 250 °C up to 800 °C. The presented results show the influence of the initial conditions on the quench front propagation and the complexity of the phenomenon.

  13. Active learning of Pareto fronts.

    Science.gov (United States)

    Campigotto, Paolo; Passerini, Andrea; Battiti, Roberto

    2014-03-01

    This paper introduces the active learning of Pareto fronts (ALP) algorithm, a novel approach to recover the Pareto front of a multiobjective optimization problem. ALP casts the identification of the Pareto front into a supervised machine learning task. This approach enables an analytical model of the Pareto front to be built. The computational effort in generating the supervised information is reduced by an active learning strategy. In particular, the model is learned from a set of informative training objective vectors. The training objective vectors are approximated Pareto-optimal vectors obtained by solving different scalarized problem instances. The experimental results show that ALP achieves an accurate Pareto front approximation with a lower computational effort than state-of-the-art estimation of distribution algorithms and widely known genetic techniques.

  14. Snowplow Injection Front Effects

    Science.gov (United States)

    Moore, T. E.; Chandler, M. O.; Buzulukova, N.; Collinson, G. A.; Kepko, E. L.; Garcia-Sage, K. S.; Henderson, M. G.; Sitnov, M. I.

    2013-01-01

    As the Polar spacecraft apogee precessed through the magnetic equator in 2001, Polar encountered numerous substorm events in the region between geosynchronous orbit and 10 RE geocentric distance; most of them in the plasma sheet boundary layers. Of these, a small number was recorded near the neutral sheet in the evening sector. Polar/Thermal Ion Dynamics Experiment provides a unique perspective on the lowest-energy ion plasma, showing that these events exhibited a damped wavelike character, initiated by a burst of radially outward flow transverse to the local magnetic field at approximately 80 km/s. They then exhibit strongly damped cycles of inward/outward flow with a period of several minutes. After one or two cycles, they culminated in a hot plasma electron and ion injection, quite similar to those observed at geosynchronous orbit. Cold plasmaspheric plasmas comprise the outward flow cycles, while the inward flow cycles contain counterstreaming field-parallel polar wind-like flows. The observed wavelike structure, preceding the arrival of an earthward moving substorm injection front, suggests an outward displacement driven by the inward motion at local times closer to midnight, that is, a "snowplow" effect. The damped in/out flows are consistent with interchange oscillations driven by the arrival at the observed local time by an injection originating at greater radius and local time.

  15. Novel RGO/α-FeOOH supported catalyst for Fenton oxidation of phenol at a wide pH range using solar-light-driven irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Ying, E-mail: yingwang@bnu.edu.cn [The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875 (China); Fang, Jiasheng, E-mail: fangfangcanfly@163.com [The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875 (China); School of Chemistry and Chemical Engineering, Southeast University, Jiangsu Optoelectronic Functional Materials and Engineering Laboratory, Nanjing 211189 (China); Crittenden, John C., E-mail: John.Crittenden@ce.gatech.edu [School of Civil and Environmental Engineering and the Brook Byers Institute for Sustainable Systems, Georgia Institute of Technology, Atlanta, GA 30332-0595 (United States); Shen, Chanchan [The Key Laboratory of Water and Sediment Sciences, Ministry of Education, School of Environment, Beijing Normal University, Beijing 100875 (China)

    2017-05-05

    Graphical abstract: Schematic of the preparation of RF supported catalysts and the reaction mechanism for SLD Fenton catalytic degradation of aqueous phenol. - Highlights: • Novel SLD Fenton catalyst was synthesized via in-situ induced self-assembly process. • RGO improved light-harvesting capacity and enhanced electro-transport performance. • Visible light irradiation accelerated reaction and extended operating pHs (4.0–8.0). • H{sub 2}O{sub 2} reduction and H{sub 2}O oxidation yielded ·OH in Fe{sup Ⅱ}/Fe{sup Ⅲ} and Fe{sup Ⅲ}/Fe{sup Ⅳ} cycling process. - Abstract: A novel solar-light-driven (SLD) Fenton catalyst was developed by reducing the ferrous-ion onto graphene oxide (GO) and forming reduced graphene oxide/α-FeOOH composites (RF) via in-situ induced self-assembly process. The RF was supported on several mesoporous supports (i.e., Al-MCM-41, MCM-41 and γ-Al{sub 2}O{sub 3}). The activity, stability and energy use for phenol oxidation were systematically studied for a wide pH range. Furthermore, the catalytic mechanism at acid and alkaline aqueous conditions was also elucidated. The results showed that Fe(II) was reduced onto GO nanosheets and α-FeOOH crystals were formed during the self-assembly process. Compared with Fenton reaction without SLD irradiation, the visible light irradiation not only dramatically accelerated the rate of Fenton-based reactions, but also extended the operating pH for the Fenton reaction (from 4.0 to 8.0). The phenol oxidation on RF supported catalysts was fitting well with the pseudo-first-order kinetics, and needed low initiating energy, insensitive to the reacting temperature changes (273–318 K). The Al-MCM-41 supported RF was a more highly energy-efficient catalyst with the prominent catalytic activity at wide operating pHs. During the reaction, ·OH radicals were generated by the SLD irradiation from H{sub 2}O{sub 2} reduction and H{sub 2}O oxidation in the Fe{sup Ⅱ}/Fe{sup Ⅲ} and Fe{sup Ⅲ}/Fe{sup

  16. Understanding charge transport in non-doped pristine and surface passivated hematite (Fe2O3) nanorods under front and backside illumination in the context of light induced water splitting.

    Science.gov (United States)

    Bassi, Prince Saurabh; Xianglin, Li; Fang, Yanan; Loo, Joachim Say Chye; Barber, James; Wong, Lydia Helena

    2016-11-09

    Hematite (Fe2O3) nanorods on FTO substrates have been proven to be promising photoanodes for solar fuel production but only with high temperature thermal activation which allows diffusion of tin (Sn) ions from FTO, eventually enhancing their conductivity. Hence, there is a trade-off between the conductivity of Fe2O3, and the degradation of FTO occurring at high annealing temperatures (>750 °C). Here, we present a comprehensive study on undoped Fe2O3 nanorods under front and back illumination to find the optimum annealing temperature. Bulk/surface charge transport efficiency analysis demonstrates minimum bulk recombination indicating overall high quality crystalline Fe2O3 and the preservation of FTO conductivity. Surface recombination is further improved by growing a TiOx overlayer, which improves the photocurrent density from 0.2 mA cm(-2) (backside) to 1.2 mA cm(-2) under front side and 0.8 mA cm(-2) under backside illumination. It is evident from this study that the performance of undoped and unpassivated hematite nanorods is limited by electron transport, whereas that of doped/passivated hematite nanorods is limited by hole transport.

  17. MoonLIGHT, a Lunar Laser Ranging Retroreflector Array for the 21st Century, and the ASI-INFN Etrusco-2 project

    Science.gov (United States)

    Delle Monache, Giovanni O.; Dell'Agnello, S.; Currie, D.; Martini, M.; Vittori, R.; Cantone, C.; Boni, A.; Berardi, S.; Patrizi, G.; Maiello, M.; Tibuzzi, M.; Garattini, M.; Lops, C.; Ciocci, E.; Graziosi, C.; Bianco, G.; Intaglietta, N.

    2012-05-01

    Since the 1970s Lunar Laser Ranging (LLR) to the Apollo Cube Corner Retroreflector (CCR) arrays supplied almost all significant tests of General Relativity and significant information on the composition and origin of the moon. In the 1970s Apollo LLR arrays contributed a negligible fraction of the ranging error budget. Since the ranging capabilities of ground stations improved by more than two orders of magnitude, now, because of the lunar librations, Apollo CCR arrays dominate the error budget. With the project MoonLIGHT in 2006 INFN-LNF joined UMD in the development and test of a new-generation LLR payload made by a single CCR unaffected by librations. In particular, INFN-LNF built and is operating a new experimental apparatus (SCF) and created a new industry-standard test procedure (SCF-Test) to characterize the thermal behavior and the optical performance of CCRs in simulated space conditions. Our key experimental innovation is the concurrent measurement and modeling of the optical FFDP and the temperature distribution of retroreflector payloads under thermal conditions produced with a close-match solar simulator. These capabilities provide: unique pre-launch performance validation of the space segment of LLR/SLR. Results of the SCF-Test of our CCR payload will be presented. Negotiations are underway to propose our payload and SCF-Test services for precision gravity and lunar science measurements with next robotic lunar landing missions. We will describe the addition of the CCR optical Wavefront Fizeau Interferogram (WFI) concurrently to FFDP/temperature measurements in the framework of an ASI-INFN project, ETRUSCO-2. The main goals of the latter are: development of a standard GNSS laser Retroreflector Array; a second SCF; SCF-Test of Galileo, GPS and other ‘as-built’ GNSS retroreflector payloads. Results on analysis of Apollo LLR data and search of new gravitational physics with LLR, Mercury Radar Ranging, SLR of LAGEOS (Laser GEOdynamics Satellite) will

  18. Fronts in Large Marine Ecosystems

    Science.gov (United States)

    Belkin, Igor M.; Cornillon, Peter C.; Sherman, Kenneth

    2009-04-01

    Oceanic fronts shape marine ecosystems; therefore front mapping and characterization are among the most important aspects of physical oceanography. Here we report on the first global remote sensing survey of fronts in the Large Marine Ecosystems (LME). This survey is based on a unique frontal data archive assembled at the University of Rhode Island. Thermal fronts were automatically derived with the edge detection algorithm of Cayula and Cornillon (1992, 1995, 1996) from 12 years of twice-daily, global, 9-km resolution satellite sea surface temperature (SST) fields to produce synoptic (nearly instantaneous) frontal maps, and to compute the long-term mean frequency of occurrence of SST fronts and their gradients. These synoptic and long-term maps were used to identify major quasi-stationary fronts and to derive provisional frontal distribution maps for all LMEs. Since SST fronts are typically collocated with fronts in other water properties such as salinity, density and chlorophyll, digital frontal paths from SST frontal maps can be used in studies of physical-biological correlations at fronts. Frontal patterns in several exemplary LMEs are described and compared, including those for: the East and West Bering Sea LMEs, Sea of Okhotsk LME, East China Sea LME, Yellow Sea LME, North Sea LME, East and West Greenland Shelf LMEs, Newfoundland-Labrador Shelf LME, Northeast and Southeast US Continental Shelf LMEs, Gulf of Mexico LME, and Patagonian Shelf LME. Seasonal evolution of frontal patterns in major upwelling zones reveals an order-of-magnitude growth of frontal scales from summer to winter. A classification of LMEs with regard to the origin and physics of their respective dominant fronts is presented. The proposed classification lends itself to comparative studies of frontal ecosystems.

  19. Depth enhancement of multi-layer light field display using polarization dependent internal reflection.

    Science.gov (United States)

    Jo, Na-Young; Lim, Hong-Gi; Lee, Sung-Keun; Kim, Yong-Soo; Park, Jae-Hyeung

    2013-12-02

    A technique to enhance the depth range of the multi-layer light field three-dimensional display is proposed. A set of the optical plates are stacked in front of the conventional multi-layer light field display, creating additional internal reflection for one polarization state. By switching between two orthogonal polarization states in synchronization with the displayed three-dimensional images, the depth range of the display can be doubled. The proposed method is verified experimentally, confirming its feasibility.

  20. Landslide-susceptibility analysis using light detection and ranging-derived digital elevation models and logistic regression models: a case study in Mizunami City, Japan

    Science.gov (United States)

    Wang, Liang-Jie; Sawada, Kazuhide; Moriguchi, Shuji

    2013-01-01

    To mitigate the damage caused by landslide disasters, different mathematical models have been applied to predict landslide spatial distribution characteristics. Although some researchers have achieved excellent results around the world, few studies take the spatial resolution of the database into account. Four types of digital elevation model (DEM) ranging from 2 to 20 m derived from light detection and ranging technology to analyze landslide susceptibility in Mizunami City, Gifu Prefecture, Japan, are presented. Fifteen landslide-causative factors are considered using a logistic-regression approach to create models for landslide potential analysis. Pre-existing landslide bodies are used to evaluate the performance of the four models. The results revealed that the 20-m model had the highest classification accuracy (71.9%), whereas the 2-m model had the lowest value (68.7%). In the 2-m model, 89.4% of the landslide bodies fit in the medium to very high categories. For the 20-m model, only 83.3% of the landslide bodies were concentrated in the medium to very high classes. When the cell size decreases from 20 to 2 m, the area under the relative operative characteristic increases from 0.68 to 0.77. Therefore, higher-resolution DEMs would provide better results for landslide-susceptibility mapping.

  1. Depth to Coal Mining in the Colorado Front Range (frimndpthu)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — This file is a digital polygon representation of the depth to (overburden above) abandoned underground coal mines in the Boulder-Weld coal field, Denver Basin,...

  2. Wildfire risk transmission in the Colorado Front Range, USA

    Science.gov (United States)

    Jessica R. Haas; David E. Calkin; Matthew P. Thompson

    2014-01-01

    Wildfires are a global phenomenon that in some circumstances can result in human casualties, economic loss, and ecosystem service degradation. In this article we spatially identify wildfire risk transmission pathways and locate the areas of highest exposure of human populations to wildland fires under severe, but not uncommon, weather events. We quantify varying levels...

  3. USGS Interactive Map of the Colorado Front Range Infrastructure Resources

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Infrastructure, such as roads, airports, water and energy transmission and distribution facilities, sewage treatment plants, and many other facilities, is vital to...

  4. Validity of Dynamic Light Scattering Method to Analyze a Range of Gold and Copper Nanoparticle Sizes Attained by Solids Laser Ablation in Liquid

    Directory of Open Access Journals (Sweden)

    Yu. V. Golubenko

    2014-01-01

    Full Text Available Nanoparticles of metals possess a whole series of features, concerned with it’s sizes, this leads to appearing or unusual electromagnetic and optical properties, which are untypical for particulates.An extended method of receiving nanoparticles by means of laser radiation is pulse laser ablation of hard targets in liquid medium.Varying the parameters of laser radiation, such as wavelength of laser radiation, energy density, etc., we can operate the size and shape of the resultant particles.The greatest trend of application in medicine have the nanoparticles of iron, copper, silver, silicon, magnesium, gold and zinc.The subject matter in this work is nanoparticles of copper and gold, received by means of laser ablation of hard targets in liquid medium.The aim of exploration, represented in the article, is the estimation of application of the dynamic light scattering method for determination of the range of nanoparticles sizes in the colloidal solution.For studying of the laser ablation process was chosen the second harmonic of Nd:YAG laser with the wavelength of 532 nm. Special attention was spared for the description of the experiment technique of receiving of nanoparticles.As the liquid medium ethanol and distillation water were used.For exploration of the received colloidal system have been used the next methods: DLS, transmission electron microscopy (TEM and scanning electron microscopy (SEM.The results of measuring by DLS method showed that colloidal solution of the copper in the ethanol is the steady system. Copper nanoparticle’s size reaches 200 nm and is staying in the same size for some time.Received system from the gold’s nanoparticles is polydisperse, unsteady and has a big range of the nanoparticle’s sizes. This fact was confirmed by means of photos, got from the TEM FEI Tecnai G2F20 + GIF and SEM Helios NanoLab 660. The range of the gold nanoparticle’s sizes is from 5 to 60 nm. So, it has been proved that the DLS method is

  5. "Front" hotshet izvinitsja / Aleksandr Ikonnikov

    Index Scriptorium Estoniae

    Ikonnikov, Aleksandr

    2003-01-01

    Põhiliselt vene rahvusest noori ühendava liikumise "Front" esindajad kavatsevad kohtuda USA suursaadikuga Eestis ja vabandada kevadel suursaatkonna ees vägivallatsemisega lõppenud meeleavalduse pärast

  6. Photovoltaic cells based on ternary P3HT:PCBM:polymethine dye active layer transparent in the visible range of light

    Energy Technology Data Exchange (ETDEWEB)

    Bliznyuk, Valery N., E-mail: vblizny@clemson.edu [Department of Materials Science and Engineering, Clemson University, Clemson, SC, 29634 (United States); Gasiorowski, Jacek [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Ishchenko, Alexander A.; Bulavko, Gennadiy V. [Institute of Organic Chemistry, National Academy of Sciences of Ukraine, 5 Murmanskaya str., Kiev 02660 (Ukraine); Rahaman, Mahfujur [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Hingerl, Kurt [Center for Interface and Nanoanalytics, Johannes Kepler University, Linz 4040 (Austria); Zahn, Dietrich R.T. [Semiconductor Physics, Technische Universität Chemnitz, D-09107 Chemnitz (Germany); Sariciftci, Niyazi S. [Linz Institute for Organic Solar Cells (LIOS), Physical Chemistry, Johannes Kepler University, Linz 4040 (Austria)

    2016-12-15

    Highlights: • Addition of a polymethine dye to P3HT:PCBM bulk-heterojunction (BHJ) films leads to a compositionally induced transparency in the system. • Variation of the complex refractive index in binary and ternary BHJ films has been studied with spectroscopic ellipsometry. • Power conversion efficiency of ternary BHJ solar cells is determined by the dye composition and photodoping. - Abstract: Optical and photovoltaic properties were studied for ternary photovoltaic cells containing a traditional donor-acceptor bulk-heterojunction (BHJ) active layer modified with polymethine dye molecules in a broad range of compositions and wavelengths. An effect of composition induced optical transparency, due to the strong modification of the density of states, was observed for symmetrical compositions with approximately equal amount of components. Based on our spectroscopic ellipsometry and atomic force microscopy (AFM) studies we can suggest that the variation of the refractive index, which is significantly reduced in the visible range for ternary systems, is involved in the physical mechanism of the phenomenon. Despite of an addition of the IR absorbing component (which allows broadening of the absorption band to up to 800 nm) no improvement in the power conversion efficiency (PCE) is observed in comparison to the binary BHJ system (P3HT:PCBM). Nevertheless, we believe that further advance of the efficiency will be possible if the energy levels will be chemically designed to avoid formation of charge traps at the BHJ interface during light excitation. Such fine adjustment of the system should become possible with a proper choice of polymer:dye composition due to a high versatility of the polymethine dyes demonstrated in previous studies.

  7. Parameterizing floodplain vegetation roughness using Airborne Light Detection and Ranging (LiDAR) on a 2D hydrodynamic model of the Lower Yuba River, CA

    Science.gov (United States)

    Abu-Aly, T. R.; Pasternack, G. B.; Wyrick, J. R.; Barker, R.; Massa, D.; Johnson, T.

    2011-12-01

    Riparian vegetation in lowland rivers has an important effect on hydrodynamics that needs to be accounted for in predictive hydrodynamic modeling. Present-day 2D hydrodynamic models can spatially distribute vegetation, and often do so using discrete polygons to characterize ostensibly uniform vegetative patches into a small set of different vegetation class types. Then roughness values are empirically assigned to each patch type. In order for 2D models to accurately capture the complex out-of-bank flow interactions, a new methodology is needed to bridge a physical connection between vegetation presence and flow resistance at the reach scale. Airborne Light Detection and Ranging enables mapping the 1-2 m resolution grid of vegetation presence and canopy height. In this study a next-generation algorithm was used to spatially distribute stage-dependent channel roughness at the 1-m scale over ~30-km of gravel-bed river corridor using equations from atmospheric boundary layer theory that reduce the data inputs to just estimated water depth and canopy height. Then 2D models were run for flows ranging from 0.2-20 times bankfull discharge both with and without spatially distributed vegetation. Results were analyzed to gain insight into the stage-dependent effects of vegetation on velocities, flow paths, and sediment transport capacity. At the flood flow of 21,100 cfs, adding vegetation caused an 8.0% increase in the wetted area, a 7.4% increase in the mean depth, and a 17.5% decrease in the mean velocity compared with the unvegetated model. The results showed that vegetation has a strong channelization effect on the flow, increasing mid-channel velocities and diverting flow away from densely vegetated areas. In the floodplain, vegetation stands caused preferential flow paths that were otherwise unaccounted for in the unvegetated model runs.

  8. Leaf Area Index (LAI Estimation in Boreal Mixedwood Forest of Ontario, Canada Using Light Detection and Ranging (LiDAR and WorldView-2 Imagery

    Directory of Open Access Journals (Sweden)

    Paul Treitz

    2013-10-01

    Full Text Available Leaf Area Index (LAI is an important input variable for forest ecosystem modeling as it is a factor in predicting productivity and biomass, two key aspects of forest health. Current in situ methods of determining LAI are sometimes destructive and generally very time consuming. Other LAI derivation methods, mainly satellite-based in nature, do not provide sufficient spatial resolution or the precision required by forest managers for tactical planning. This paper focuses on estimating LAI from: (i height and density metrics derived from Light Detection and Ranging (LiDAR; (ii spectral vegetation indices (SVIs, in particular the Normalized Difference Vegetation Index (NDVI; and (iii a combination of these methods. For the Hearst Forest of Northern Ontario, in situ measurements of LAI were derived from digital hemispherical photographs (DHPs while remote sensing variables were derived from low density LiDAR (i.e., 1 m−2 and high spatial resolution WorldView-2 data (2 m. Multiple Linear Regression (MLR models were generated using these variables. Results from these analyses demonstrate: (i moderate explanatory power (i.e., R2 = 0.53 for LiDAR height and density metrics that have proven to be related to canopy structure; (ii no relationship when using SVIs; and (iii no significant improvement of LiDAR models when combining them with SVI variables. The results suggest that LiDAR models in boreal forest environments provide satisfactory estimations of LAI, even with narrow ranges of LAI for model calibration. Models derived from low point density LiDAR in a mixedwood boreal environment seem to offer a reliable method of estimating LAI at high spatial resolution for decision makers in the forestry community. This method can be easily incorporated into simultaneous modeling efforts for forest inventory variables using LiDAR.

  9. Collective membrane motions in the mesoscopic range and their modulation by the binding of a monomolecular protein layer of streptavidin studied by dynamic light scattering

    Science.gov (United States)

    Hirn, Rainer; Benz, Roland; Bayerl, Thomas M.

    1999-05-01

    Using a dedicated dynamic light scattering setup, we have studied the angstrom-scale amplitude undulations of freely suspended planar lipid bilayers, so-called black lipid membranes (BLM's), over a previously not accessible spread of frequencies (relaxation times ranging from 10-2 to 10-6 s) and wave vectors (250 cm-1membrane modes, and the results obtained for a synthetic lecithin BLM are found to be in excellent agreement with the theoretical predictions. In particular, the transition of the transverse shear mode of a BLM between an oscillatory or propagating regime and an overdamped regime by passing through a bifurcation point was clearly observed. It is shown that the collective motions in the time- and wave-vector regime covered are dominated by the membrane tension, while membrane curvature does not contribute. The binding of the protein streptavidin to the BLM via membrane anchored specific binders (receptors) causes a drastic change in frequency and amplitude of the collective motions, resulting in a drastic increase of the membrane tension by a factor of 3. This effect is probably caused by a steric hindrance of the transverse shear motions of the lipid by the tightly bound proteins.

  10. Association of Sand Dust Particles with Pulmonary Function and Respiratory Symptoms in Adult Patients with Asthma in Western Japan Using Light Detection and Ranging: A Panel Study

    Directory of Open Access Journals (Sweden)

    Masanari Watanabe

    2015-10-01

    Full Text Available Light detection and ranging (LIDAR can estimate daily volumes of sand dust particles from the East Asian desert to Japan. The objective of this study was to investigate the relationship between sand dust particles and pulmonary function, and respiratory symptoms in adult patients with asthma. One hundred thirty-seven patients were included in the study. From March 2013 to May 2013, the patients measured their morning peak expiratory flow (PEF and kept daily lower respiratory symptom diaries. A linear mixed model was used to estimate the correlation of the median daily levels of sand dust particles, symptoms scores, and PEF. A heavy sand dust day was defined as an hourly concentration of sand dust particles of >0.1 km−1. By this criterion, there were 8 heavy sand dust days during the study period. Elevated sand dust particles levels were significantly associated with the symptom score (0.04; 95% confidence interval (CI; 0.03, 0.05, and this increase persisted for 5 days. There was no significant association between PEF and heavy dust exposure (0.01 L/min; 95% CI, −0.62, 0.11. The present study found that sand dust particles were significantly associated with worsened lower respiratory tract symptoms in adult patients with asthma, but not with pulmonary function.

  11. Association of Sand Dust Particles with Pulmonary Function and Respiratory Symptoms in Adult Patients with Asthma in Western Japan Using Light Detection and Ranging: A Panel Study

    Science.gov (United States)

    Watanabe, Masanari; Noma, Hisashi; Kurai, Jun; Shimizu, Atsushi; Sano, Hiroyuki; Kato, Kazuhiro; Mikami, Masaaki; Ueda, Yasuto; Tatsukawa, Toshiyuki; Ohga, Hideki; Yamasaki, Akira; Igishi, Tadashi; Kitano, Hiroya; Shimizu, Eiji

    2015-01-01

    Light detection and ranging (LIDAR) can estimate daily volumes of sand dust particles from the East Asian desert to Japan. The objective of this study was to investigate the relationship between sand dust particles and pulmonary function, and respiratory symptoms in adult patients with asthma. One hundred thirty-seven patients were included in the study. From March 2013 to May 2013, the patients measured their morning peak expiratory flow (PEF) and kept daily lower respiratory symptom diaries. A linear mixed model was used to estimate the correlation of the median daily levels of sand dust particles, symptoms scores, and PEF. A heavy sand dust day was defined as an hourly concentration of sand dust particles of >0.1 km−1. By this criterion, there were 8 heavy sand dust days during the study period. Elevated sand dust particles levels were significantly associated with the symptom score (0.04; 95% confidence interval (CI); 0.03, 0.05), and this increase persisted for 5 days. There was no significant association between PEF and heavy dust exposure (0.01 L/min; 95% CI, −0.62, 0.11). The present study found that sand dust particles were significantly associated with worsened lower respiratory tract symptoms in adult patients with asthma, but not with pulmonary function. PMID:26501307

  12. Consumer preferences for front-of-pack calories labelling

    NARCIS (Netherlands)

    Kleef, van E.; Trijp, van J.C.M.; Paeps, F.; Fernández-Celemín, L.

    2008-01-01

    Objective In light of the emerging obesity pandemic, front-of-pack calories labels may be an important tool to assist consumers in making informed healthier food choices. However, there is little prior research to guide key decisions on whether caloric content should be expressed in absolute terms

  13. The impact of interpretive and reductive front-of-pack labels on food choice and willingness to pay.

    Science.gov (United States)

    Talati, Zenobia; Norman, Richard; Pettigrew, Simone; Neal, Bruce; Kelly, Bridget; Dixon, Helen; Ball, Kylie; Miller, Caroline; Shilton, Trevor

    2017-12-19

    This study examined how front-of-pack labels and product healthfulness affect choice and willingness to pay across a range of foods. It was hypothesized that: (i) product choice and (ii) willingness to pay would be more aligned with product healthfulness when healthfulness was expressed through the Health Star Rating, followed by the Multiple Traffic Light, then the Daily Intake Guide, and (iii) the Nutrition Facts Panel would be viewed infrequently. Adults and children aged 10+ years (n = 2069) completed an online discrete choice task involving mock food packages. A 4 food type (cookies, corn flakes, pizza, yoghurt) × 2 front-of-pack label presence (present, absent) × 3 front-of-pack label type (Daily Intake Guide, Multiple Traffic Light, Health Star Rating) × 3 price (cheap, moderate, expensive) × 3 healthfulness (less healthy, moderately healthy, healthier) design was used. A 30 s time limit was imposed for each choice. Of the three front-of-pack labels tested, the Health Star Rating produced the largest differences in choices, with 40% (95% CIs: 38%-42%) of respondents selecting the healthier variant, 33% selecting the moderately healthy variant (95% CIs: 31%-35%), and 23% (95% CIs: 21%-24%) selecting the less healthy variant of the four products included in the study. The Multiple Traffic Light led to significant differences in choices between healthier (35%, 95% CIs: 33%-37%) and less healthy products (29%, 95% CIs: 27%-31%), but not moderately healthy products (32%, 95% CIs: 30%-34%). No significant differences in choices were observed by product healthfulness when the Daily Intake Guide was present. Only the Health Star Rating resulted in a significantly greater willingness to pay for healthier versus less healthy products. The Nutrition Facts Panel was viewed for only 7% of all mock packages. Front-of-pack labels that are more interpretive, such as the Health Star Rating, can be more effective at directing consumers towards healthier choices than

  14. Kinetics of a plasma streamer ionization front

    Science.gov (United States)

    Taccogna, Francesco; Pellegrini, Fabrizio

    2018-02-01

    A streamer is a non-linear and non-local gas breakdown mode. Its large-scale coherent structures, such as the ionization front, are the final results of a hierarchical cascade starting from the single particle dynamics. Therefore, this phenomenon covers, by definition, different space and time scales. In this study, we have reproduced the ionization front formation and development by means of a particle-based numerical methodology. The physical system investigated concerns of a high-voltage ns-pulsed surface dielectric barrier discharge. Different reduced electric field regimes ranging from 50 to 500 Td have been considered for two gases: pure atomic Ar and molecular N2. Results have shown the detailed structure of the negative streamer: the leading edge, the head, the interior and the tail. Its dynamical evolution and the front propagation velocity have been calculated for the different cases. Finally, the deviation of the electron energy distribution function from equilibrium behavior has been pointed out as a result of a fast and very localized phenomenon.

  15. Antarctic Ice-Shelf Front Dynamics from ICESat

    Science.gov (United States)

    Robbins, John W.; Zwally, H. Jay; Saba, Jack L.; Yi, Donghui

    2012-01-01

    Time variable elevation profiles from ICESat Laser Altimetry over the period 2003-2009 provide a means to quantitatively detect and track topographic features on polar ice surfaces. The results of this study provide a measure of the horizontal motion of ice-shelf fronts. We examine the time histories of elevation profiles crossing the ice fronts of the Ross, Ronne, Filchner, Riiser-Larson and Fimbul shelves. This provides a basis for estimating dynamics in two dimensions, i.e. in elevation and horizontally in the along-track direction. Ice front velocities, corrected for ground-track intersection angle, range from nearly static to 1.1 km/yr. In many examples, a decrease in elevation up to 1 m/yr near the shelf frontis also detectable. Examples of tabular calving along shelf fronts are seen in some elevation profiles and are confirmed by corresponding MODIS imagery.

  16. Can front-of-pack labelling schemes guide healthier food choices? Australian shoppers' responses to seven labelling formats.

    Science.gov (United States)

    Watson, Wendy L; Kelly, Bridget; Hector, Debra; Hughes, Clare; King, Lesley; Crawford, Jennifer; Sergeant, John; Chapman, Kathy

    2014-01-01

    There is evidence that easily accessible, comprehensible and consistent nutrient information on the front of packaged foods could assist shoppers to make healthier food choices. This study used an online questionnaire of 4357 grocery shoppers to examine Australian shoppers' ability to use a range of front-of-pack labels to identify healthier food products. Seven different front-of-pack labelling schemes comprising variants of the Traffic Light labelling scheme and the Percentage Daily Intake scheme, and a star rating scheme, were applied to nine pairs of commonly purchased food products. Participants could also access a nutrition information panel for each product. Participants were able to identify the healthier product in each comparison over 80% of the time using any of the five schemes that provided information on multiple nutrients. No individual scheme performed significantly better in terms of shoppers' ability to determine the healthier product, shopper reliance on the 'back-of-pack' nutrition information panel, and speed of use. The scheme that provided information about energy only and a scheme with limited numerical information of nutrient type or content performed poorly, as did the nutrition information panel alone (control). Further consumer testing is necessary to determine the optimal format and content of an interpretive front-of-pack nutrition labelling scheme. Copyright © 2013 Elsevier Ltd. All rights reserved.

  17. Cold Fronts in Clusters of Galaxies: Observations and Modeling

    Science.gov (United States)

    Markevitch, Maxim

    2012-01-01

    Mergers of galaxy clusters -- some of the most energetic events in the Universe -- produce disturbances in hot intracluster medium, such as shocks and cold fronts, that can be used as tools to study the physics of galaxy clusters. Cold fronts may constrain viscosity and the structure and strength of the cluster magnetic fields. Combined with radio data, these observations also shed light on the production of ultrarelativistic particles that are known to coexist with the cluster thermal plasma. This talk will summarize the current X-ray observations of cluster mergers, as well as some recent radio data and high resolution hydrodynamic simulations.

  18. Front dynamics in turbulent media

    CERN Document Server

    Martí, A C; Sancho, J M

    1997-01-01

    A study of a stable front propagating in a turbulent medium is presented. The front is generated through a reaction-diffusion equation, and the turbulent medium is statistically modeled using a Langevin equation. Numerical simulations indicate the presence of two different dynamical regimes. These regimes appear when the turbulent flow either wrinkles a still rather sharp propagating interfase or broadens it. Specific dependences of the propagating velocities on stirring intensities appropriate to each case are found and fitted when possible according to theoretically predicted laws. Different turbulent spectra are considered.

  19. The responses of guard and mesophyll cell photosynthesis to CO2, O2, light, and water stress in a range of species are similar

    National Research Council Canada - National Science Library

    Tracy Lawson; Kevin Oxborough; James I. L. Morison; Neil R. Baker

    2003-01-01

    .... As measurement light intensity was increased, guard cells from the lower leaf surfaces of C. communis and V. faba showed larger reductions in photosynthetic efficiency than those from the upper surfaces...

  20. FRET-Mediated Long-Range Wavelength Transformation by Photoconvertible Fluorescent Proteins as an Efficient Mechanism to Generate Orange-Red Light in Symbiotic Deep Water Corals

    OpenAIRE

    Bollati, Elena; Plimmer, Daniel; D'Angelo, Cecilia; Wiedenmann, J?rg

    2017-01-01

    Photoconvertible fluorescent proteins (pcRFPs) are a group of fluorophores that undergo an irreversible green-to-red shift in emission colour upon irradiation with near-ultraviolet (near-UV) light. Despite their wide application in biotechnology, the high-level expression of pcRFPs in mesophotic and depth-generalist coral species currently lacks a biological explanation. Additionally, reduced penetration of near-UV wavelengths in water poses the question whether light-driven photoconversion i...

  1. Topological defects govern crack front motion and facet formation on broken surfaces

    Science.gov (United States)

    Kolvin, Itamar; Cohen, Gil; Fineberg, Jay

    2018-02-01

    Cracks develop intricate patterns on the surfaces that they create. As faceted fracture surfaces are commonly formed by slow tensile cracks in both crystalline and amorphous materials, facet formation and structure cannot reflect microscopic order. Although fracture mechanics predict that slow crack fronts should be straight and form mirror-like surfaces, facet-forming fronts propagate simultaneously within different planes separated by steps. Here we show that these steps are topological defects of crack fronts and that crack front separation into disconnected overlapping segments provides the condition for step stability. Real-time imaging of propagating crack fronts combined with surface measurements shows that crack dynamics are governed by localized steps that drift at a constant angle to the local front propagation direction while their increased dissipation couples to long-ranged elasticity to determine front shapes. We study how three-dimensional topology couples to two-dimensional fracture dynamics to provide a fundamental picture of how patterned surfaces are generated.

  2. ATLAS LAr Phase upgrade of the Front End Electronics

    CERN Document Server

    Newcomer, Mitchel; The ATLAS collaboration

    2016-01-01

    The Phase II upgrade of the ATLAS Liquid Argon detector includes a 17 bit dynamic range front end amplifier with a two or three gain multi‐pole shaper employing CR‐(RC)n shaping. Each gain stage of the shaper will be followed by a 40Msps, 14b dynamic range, 12‐13b ENOB digitizer, serializer and fiber optic driver. A study is underway to see if a single technology (65nm or 130nm CMOS) will be suitable for all blocks up to the optical Link, enabling consideration of the development a Front End System On a Chip (FESOC).

  3. Biomechanics of front and back squat exercises

    Energy Technology Data Exchange (ETDEWEB)

    Braidot, A A [Laboratorio de Biomecanica FI-UNER. Ruta 11 Km 10 Oro Verde Entre Rios (Argentina); Brusa, M H [Laboratorio de Biomecanica FI-UNER. Ruta 11 Km 10 Oro Verde Entre Rios (Argentina); Lestussi, F E [Laboratorio de Biomecanica FI-UNER. Ruta 11 Km 10 Oro Verde Entre Rios (Argentina); Parera, G P [Licenciatura en KinesiologIa y FisiatrIa Universidad Abierta Interamericana. Sede Regional Rosario (Argentina)

    2007-11-15

    Squat constitutes one of the most popular exercises to strengthen the muscles of the lower limbs. It is considered one of the most widely spread exercises for muscle sport training and is part of the competition movements comprised within olympic weight-lifting. In physical rehabilitation, squats are used for muscular recovery after different injuries of the lower limbs, especially the knee. In previous anterior cruciate ligament injuries, the mini-squats are generally used, in a knee flexion motion range from 0 deg. to 50 deg. because in this range the shear forces, the tibiofemoral and patellofemoral compression forces decrease related to greater flexion angles. The aim of this work is to make a comparative bidimensional study of the kinematic and dynamic variables of the excecution of the parallel squat exercise with the front and back bar. It is observed in the knee a better development of energy with the front bar, allowing a better muscular exercise with the same load. The mean power absorbed by the hip with the back bar is considerably greater, associated to the speed of the gesture.

  4. Biomechanics of front and back squat exercises

    Science.gov (United States)

    Braidot, A. A.; Brusa, M. H.; Lestussi, F. E.; Parera, G. P.

    2007-11-01

    Squat constitutes one of the most popular exercises to strengthen the muscles of the lower limbs. It is considered one of the most widely spread exercises for muscle sport training and is part of the competition movements comprised within olympic weight-lifting. In physical rehabilitation, squats are used for muscular recovery after different injuries of the lower limbs, especially the knee. In previous anterior cruciate ligament injuries, the mini-squats are generally used, in a knee flexion motion range from 0° to 50° because in this range the shear forces, the tibiofemoral and patellofemoral compression forces decrease related to greater flexion angles. The aim of this work is to make a comparative bidimensional study of the kinematic and dynamic variables of the excecution of the parallel squat exercise with the front and back bar. It is observed in the knee a better development of energy with the front bar, allowing a better muscular exercise with the same load. The mean power absorbed by the hip with the back bar is considerably greater, associated to the speed of the gesture.

  5. Virulence evolution at the front line of spreading epidemics.

    Science.gov (United States)

    Griette, Quentin; Raoul, Gaël; Gandon, Sylvain

    2015-11-01

    Understanding and predicting the spatial spread of emerging pathogens is a major challenge for the public health management of infectious diseases. Theoretical epidemiology shows that the speed of an epidemic is governed by the life-history characteristics of the pathogen and its ability to disperse. Rapid evolution of these traits during the invasion may thus affect the speed of epidemics. Here we study the influence of virulence evolution on the spatial spread of an epidemic. At the edge of the invasion front, we show that more virulent and transmissible genotypes are expected to win the competition with other pathogens. Behind the front line, however, more prudent exploitation strategies outcompete virulent pathogens. Crucially, even when the presence of the virulent mutant is limited to the edge of the front, the invasion speed can be dramatically altered by pathogen evolution. We support our analysis with individual-based simulations and we discuss the additional effects of demographic stochasticity taking place at the front line on virulence evolution. We confirm that an increase of virulence can occur at the front, but only if the carrying capacity of the invading pathogen is large enough. These results are discussed in the light of recent empirical studies examining virulence evolution at the edge of spreading epidemics. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  6. Three-dimensional imaging, change detection, and stability assessment during the centerline trench levee seepage experiment using terrestrial light detection and ranging technology, Twitchell Island, California, 2012

    Science.gov (United States)

    Bawden, Gerald W.; Howle, James; Bond, Sandra; Shriro, Michelle; Buck, Peter

    2014-01-01

    A full scale field seepage test was conducted on a north-south trending levee segment of a now bypassed old meander belt on Twitchell Island, California, to understand the effects of live and decaying root systems on levee seepage and slope stability. The field test in May 2012 was centered on a north-south trench with two segments: a shorter control segment and a longer seepage test segment. The complete length of the trench area measured 40.4 meters (m) near the levee centerline with mature trees located on the waterside and landside of the levee flanks. The levee was instrumented with piezometers and tensiometers to measure positive and negative porewater pressures across the levee after the trench was flooded with water and held at a constant hydraulic head during the seepage test—the results from this component of the experiment are not discussed in this report. We collected more than one billion three-dimensional light detection and ranging (lidar) data points before, during, and after the centerline seepage test to assess centimeter-scale stability of the two trees and the levee crown. During the seepage test, the waterside tree toppled (rotated 20.7 degrees) into the water. The landside tree rotated away from the levee by 5 centimeters (cm) at a height of 2 m on the tree. The paved surface of the levee crown had three regions that showed subsidence on the waterside of the trench—discussed as the northern, central, and southern features. The northern feature is an elongate region that subsided 2.1 cm over an area with an average width of 1.35 m that extends 15.8 m parallel to the trench from the northern end of the trench to just north of the trench midpoint, and is associated with a crack 1 cm in height that formed during the seepage test on the trench wall. The central subsidence feature is a semicircular region on the waterside of the trench that subsided by as much as 6.2 cm over an area 3.4 m wide and 11.2 m long. The southern feature is an elongate

  7. Volume holographic storage and multiplexing in blends of PMMA and a block methacrylic azopolymer, using 488 nm light pulses in the range of 100 ms to 1 s

    DEFF Research Database (Denmark)

    Forcen, Patricia; Oriol, Luis; Sanchez, Carlos

    2008-01-01

    Blends of polymethylmethacrylate (PMMA) and diblock methacrylic azopolymers have been investigated for holographic storage with short light pulses. Transmission electron microscopy measurements show that the dilution of the block copolymer in PMMA changes the microstructure from a lamellar to a s...

  8. Correction of the spectral calibration of the Joint European Torus core light detecting and ranging Thomson scattering diagnostic using ray tracing

    NARCIS (Netherlands)

    Hawke, J.; Scannell, R.; Maslov, M.; Migozzi, J. B.

    2013-01-01

    This work isolated the cause of the observed discrepancy between the electron temperature (T-e) measurements before and after the JET Core LIDAR Thomson Scattering (TS) diagnostic was upgraded. In the upgrade process, stray light filters positioned just before the detectors were removed from the

  9. VERUCLAY – a new type of photo-adsorbent active in the visible light range: modification of montmorillonite surface with organic surfactant

    Science.gov (United States)

    Montmorillonite K10 was treated with VeruSOL-3, a biodegradable and food-grade surfactant mixture of coconut oil, castor oil and citrus extracts, to manufacture a benign catalytic adsorbent that is active in the visible light. Veruclay was characterized by SEM, XRD, TGA, UVDRS, a...

  10. White LEDs as broad spectrum light sources for spectrophotometry: demonstration in the visible spectrum range in a diode-array spectrophotometric detector.

    Science.gov (United States)

    Piasecki, Tomasz; Breadmore, Michael C; Macka, Mirek

    2010-11-01

    Although traditional lamps, such as deuterium lamps, are suitable for bench-top instrumentation, their compatibility with the requirements of modern miniaturized instrumentation is limited. This study investigates the option of utilizing solid-state light source technology, namely white LEDs, as a broad band spectrum source for spectrophotometry. Several white light LEDs of both RGB and white phosphorus have been characterized in terms of their emission spectra and energy output and a white phosphorus Luxeon LED was then chosen for demonstration as a light source for visible-spectrum spectrophotometry conducted in CE. The Luxeon LED was fixed onto the base of a dismounted deuterium (D(2) ) lamp so that the light-emitting spot was geometrically positioned exactly where the light-emitting spot of the original D(2) lamp is placed. In this manner, the detector of a commercial CE instrument equipped with a DAD was not modified in any way. As the detector hardware and electronics remained the same, the change of the deuterium lamp for the Luxeon white LED allowed a direct comparison of their performances. Several anionic dyes as model analytes with absorption maxima between 450 and 600 nm were separated by CE in an electrolyte of 0.01 mol/L sodium tetraborate. The absorbance baseline noise as the key parameter was 5 × lower for the white LED lamp, showing clearly superior performance to the deuterium lamp in the available, i.e. visible part of the spectrum. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Firing up the front line.

    Science.gov (United States)

    Katzenbach, J R; Santamaria, J A

    1999-01-01

    For many organizations, achieving competitive advantage means eliciting superior performance from employees on the front line--the burger flippers, hotel room cleaners, and baggage handlers whose work has an enormous effect on customers. That's no easy task. Front line workers are paid low wages, have scant hope of advancement, and--not surprisingly--often care little about the company's performance. But then how do some companies succeed in engaging the emotional energy of rank-and-file workers? A team of researchers at McKinsey & Company and the Conference Board recently explored that question and discovered that one highly effective route is demonstrated by the U.S. Marine Corps. The Marines' approach to motivation follows the "mission, values, and pride" path, which researchers say is practical and relevant for the business world. More specifically, the authors say the Marines follow five practices: they over-invest in cultivating core value; prepare every person to lead, including front line supervisors; learn when to create teams and when to create single-leader work groups; attend to all employees, not just the top half; and encourage self-discipline as a way of building pride. The authors admit there are critical differences between the Marines and most businesses. But using vivid examples from companies such as KFC and Marriott International, the authors illustrate how the Marines' approach can be translated for corporate use. Sometimes, the authors maintain, minor changes in a company's standard operating procedure can have a powerful effect on front line pride and can result in substantial payoffs in company performance.

  12. Laser filamentation in air via Mathieu modulation: ranging from trajectory-predesigned curved filament to quasi-soliton and ring light bullet.

    Science.gov (United States)

    Hu, Yuze; Nie, Jinsong

    2017-06-26

    We propose theoretically various kinds of filaments via the Mathieu modulation. Our results indicate curved filaments, in-phase and out-of-phase quasi-solitons and nonlinear light bullets can be formed successfully in air. Through calculated initial Mathieu accelerating beam (MAB), curved filament is able to propagate along a predesigned elliptical trajectory. By transforming the MAB into an axial symmetrical structure with in-phase and out-of-phase modulations, we obtain two kinds of quasi-solitons in air, respectively. The latter case can even propagate in a breathing fashion. With a ring structure of MAB, we successfully form a light bullet in air that generates a chain of intensity peaks over extended distances. These unique filaments can offer significant advantages for numerous applications, such as micro engineering of materials, THz radiation generation and attosecond physics.

  13. AIRS Storm Front Approaching California (animation)

    Science.gov (United States)

    2005-01-01

    [figure removed for brevity, see original site] Click on the image for the AIRS Storm Front Approaching California Animation NASA's Atmospheric Infrared Sounder instrument is able to peel back cloud cover to reveal 3-D structure of a storm's water vapor content, information that can be used to improve weather forecast models. In this animation the initial visible cloud image series shows a front moving toward the West Coast of the United States as a low pressure area moves into the Pacific Northwest. The 'Pineapple Express,' a stream of moisture that originates in the tropics South of Hawaii and usually crosses Mexico to enter New Mexico and Texas, has shifted Westward and is also visible moving into Baja California. The area preceding the front appears to be relatively clear in the visible images. As the view shifts from the visible to the infrared wavelengths which highlight water vapor, we see both cloud areas contain heavy burdens of moisture. The area which appears clear in the visible images is seen to contain water vapor near the coastline as well. The viewpoint then rotates so that we can see the vertical cross section of the fronts. The variability of the vertical extent of water vapor and the amount is now clearly visible. The storm moving in from the Gulf of Alaska is more heavily laden with water vapor than that moving in from the Southwest. The moisture is concentrated in the lower atmosphere. The colors indicate the amount of water vapor present. Blue areas denote low water vapor content; green areas are medium water vapor content; red areas signify high water vapor content. The vertical grid for the final frame ranges from 250 millibar pressure at the top to 1000 millibar pressure at the bottom. The top is about 10 km (6.2 miles) above the surface of the Earth. The Atmospheric Infrared Sounder Experiment, with its visible, infrared, and microwave detectors, provides a three-dimensional look at Earth's weather. Working in tandem, the three instruments

  14. Microstrip-Transmission-Line Shock-Front Sensor

    Science.gov (United States)

    Leiweke, Robert J.; Smith, William C.

    1993-01-01

    Microstrip-transmission-line sensor measures velocities of low-overpressure shock fronts and offers dynamic range needed for measurements both far from and near explosions. Fabricated easily, relatively inexpensive, and repaired in field. In addition, basic geometry modified easily, as needed.

  15. Inertial forces affect fluid front displacement dynamics in a pore-throat network model.

    Science.gov (United States)

    Moebius, Franziska; Or, Dani

    2014-08-01

    into the rich pore-scale dynamics of displacement fronts; these insights not only improve the basic understanding of these ubiquitous processes, but could shed light on solute dispersion and colloids mobilization at fronts and the mechanical consequences of passing fronts.

  16. Wide-band low-noise distributed front-end for multi-gigabit CPFSK receivers

    DEFF Research Database (Denmark)

    Petersen, Anders Kongstad; Ebskamp, F; Pedersen, Rune Johan Skullerud

    1994-01-01

    In this paper a distributed optical front-end amplifier for a coherent optical CPFSK receiver is presented. The measured average input noise current density is 20 pA/√(Hz) in a 3-13 GHz bandwidth. This is the lowest value reported for a distributed optical front-end in this frequency range...

  17. Experimental and numerical investigation on the motorcycle front frame flexibility and its effect on stability

    Science.gov (United States)

    Cossalter, V.; Doria, A.; Massaro, M.; Taraborrelli, L.

    2015-08-01

    It is well known that front fork flexibility may have a significant effect on motorcycle stability. This work addresses the problem of developing lumped element models of the front fork from experimental results. The front forks of an enduro motorcycle and of a super sport motorcycle are characterized performing static, dynamic and modal tests by means of specific testing equipment. The concept of wheel twisting axis is proposed to characterize static and dynamic deformability of the front fork. Modal analysis results show the presence of two important modes of vibration of the front assembly in the low frequency range: the lateral mode and the longitudinal mode. Different lumped models are discussed and a new model that takes into account information obtained from static and dynamic tests is proposed. Simulations are carried out by means of a multibody code and show the effect of the front assembly deformability on the weave and wobble vibration modes.

  18. The responses of guard and mesophyll cell photosynthesis to CO2, O2, light, and water stress in a range of species are similar.

    Science.gov (United States)

    Lawson, Tracy; Oxborough, Kevin; Morison, James I L; Baker, Neil R

    2003-07-01

    High resolution chlorophyll a fluorescence imaging was used to compare the photosynthetic efficiency of PSII electron transport (estimated by Fq'/Fm') in guard cell chloroplasts and the underlying mesophyll in intact leaves of six different species: Commelina communis, Vicia faba, Amaranthus caudatus, Polypodium vulgare, Nicotiana tabacum, and Tradescantia albifora. While photosynthetic efficiency varied between the species, the efficiencies of guard cells and mesophyll cells were always closely matched. As measurement light intensity was increased, guard cells from the lower leaf surfaces of C. communis and V. faba showed larger reductions in photosynthetic efficiency than those from the upper surfaces. In these two species, guard cell photosynthetic efficiency responded similarly to that of the mesophyll when either light intensity or CO2 concentration during either measurement or growth was changed. In all six species, reducing the O2 concentration from 21% to 2% reduced guard cell photosynthetic efficiency, even for the C4 species A. caudatus, although the mesophyll of the C4 species did not show any O2 modulation of photosynthetic efficiency. This suggests that Rubisco activity is significant in the guard cells of these six species. When C. communis plants were water-stressed, the guard cell photosynthetic efficiency declined in parallel with that of the mesophyll. It was concluded that the photosynthetic efficiency in guard cells is determined by the same factors that determine it in the mesophyll.

  19. Seabird diving behaviour reveals the functional significance of shelf-sea fronts as foraging hotspots

    Science.gov (United States)

    Cox, S. L.; Miller, P. I.; Embling, C. B.; Scales, K. L.; Bicknell, A. W. J.; Hosegood, P. J.; Morgan, G.; Ingram, S. N.; Votier, S. C.

    2016-09-01

    Oceanic fronts are key habitats for a diverse range of marine predators, yet how they influence fine-scale foraging behaviour is poorly understood. Here, we investigated the dive behaviour of northern gannets Morus bassanus in relation to shelf-sea fronts. We GPS (global positioning system) tracked 53 breeding birds and examined the relationship between 1901 foraging dives (from time-depth recorders) and thermal fronts (identified via Earth Observation composite front mapping) in the Celtic Sea, Northeast Atlantic. We (i) used a habitat-use availability analysis to determine whether gannets preferentially dived at fronts, and (ii) compared dive characteristics in relation to fronts to investigate the functional significance of these oceanographic features. We found that relationships between gannet dive probabilities and fronts varied by frontal metric and sex. While both sexes were more likely to dive in the presence of seasonally persistent fronts, links to more ephemeral features were less clear. Here, males were positively correlated with distance to front and cross-front gradient strength, with the reverse for females. Both sexes performed two dive strategies: shallow V-shaped plunge dives with little or no active swim phase (92% of dives) and deeper U-shaped dives with an active pursuit phase of at least 3 s (8% of dives). When foraging around fronts, gannets were half as likely to engage in U-shaped dives compared with V-shaped dives, independent of sex. Moreover, V-shaped dive durations were significantly shortened around fronts. These behavioural responses support the assertion that fronts are important foraging habitats for marine predators, and suggest a possible mechanistic link between the two in terms of dive behaviour. This research also emphasizes the importance of cross-disciplinary research when attempting to understand marine ecosystems.

  20. Front Propagation in Stochastic Neural Fields

    KAUST Repository

    Bressloff, Paul C.

    2012-01-01

    We analyze the effects of extrinsic multiplicative noise on front propagation in a scalar neural field with excitatory connections. Using a separation of time scales, we represent the fluctuating front in terms of a diffusive-like displacement (wandering) of the front from its uniformly translating position at long time scales, and fluctuations in the front profile around its instantaneous position at short time scales. One major result of our analysis is a comparison between freely propagating fronts and fronts locked to an externally moving stimulus. We show that the latter are much more robust to noise, since the stochastic wandering of the mean front profile is described by an Ornstein-Uhlenbeck process rather than a Wiener process, so that the variance in front position saturates in the long time limit rather than increasing linearly with time. Finally, we consider a stochastic neural field that supports a pulled front in the deterministic limit, and show that the wandering of such a front is now subdiffusive. © 2012 Society for Industrial and Applied Mathematics.

  1. The electron spectro-microscopy beamline at National Synchrotron Light Source II: a wide photon energy range, micro-focusing beamline for photoelectron spectro-microscopies.

    Science.gov (United States)

    Reininger, R; Hulbert, S L; Johnson, P D; Sadowski, J T; Starr, D E; Chubar, O; Valla, T; Vescovo, E

    2012-02-01

    A comprehensive optical design for a high-resolution, high-flux, wide-energy range, micro-focused beamline working in the vacuum ultraviolet and soft x-ray photon energy range is proposed. The beamline is to provide monochromatic radiation to three photoelectron microscopes: a full-field x-ray photoelectron emission microscope and two scanning instruments, one dedicated to angle resolved photoemission spectroscopy (μ-ARPES) and one for ambient pressure x-ray photoelectron spectroscopy and scanning photoelectron microscopy (AP-XPS/SPEM). Microfocusing is achieved with state of the art elliptical cylinders, obtaining a spot size of 1 μm for ARPES and 0.5 μm for AP-XPS/SPEM. A detailed ray tracing analysis quantitatively evaluates the overall beamline performances.

  2. Color light-emitting diode reflection topography: validation of keratometric repeatability in a large sample of wide cylindrical-range corneas

    OpenAIRE

    Kanellopoulos AJ; Asimellis G

    2015-01-01

    Anastasios John Kanellopoulos,1,2 George Asimellis11LaserVision.gr Clinical and Research Eye Institute, Athens, Greece; 2New York University Medical School, New York, NY, USAPurpose: To investigate repeatability of steep and flat keratometry measurements, as well as astigmatism axis in cohorts with normal range and regular astigmatic such as: eyes following laser-assisted in situ keratomileusis (LASIK) and normal population, as well as cohorts of high and irregular astigmati...

  3. Holographic Optical Receiver Front End for Wireless Infrared Indoor Communications

    Science.gov (United States)

    Jivkova, S.; Kavehrad, M.

    2001-06-01

    Multispot diffuse configuration (MSDC) for indoor wireless optical communications, utilizing multibeam transmitter and angle diversity detection, is one of the most promising ways of achieving high capacities for use in high-bandwidth islands such as classrooms, hotel lobbies, shopping malls, and train stations. Typically, the optical front end of the receiver consists of an optical concentrator to increase the received optical signal power and an optical bandpass filter to reject the ambient light. Using the unique properties of holographic optical elements (HOE), we propose a novel design for the receiver optical subsystem used in MSDC. With a holographic curved mirror as an optical front end, the receiver would achieve more than an 10-dB improvement in the electrical signal-to-noise ratio compared with a bare photodetector. Features such as multifunctionality of the HOE and the receiver s small size, light weight, and low cost make the receiver front end a promising candidate for a user s portable equipment in broadband indoor wireless multimedia access.

  4. Front propagation and rejuvenation in flipping processes

    Energy Technology Data Exchange (ETDEWEB)

    Ben-naim, Eli [Los Alamos National Laboratory; Krapivsky, P I [BOSTON UNIV; Antal, T [HARVARD UNIV; Ben - Avrahm, D [HARVARD UNIV

    2008-01-01

    We study a directed flipping process that underlies the performance of the random edge simplex algorithm. In this stochastic process, which takes place on a one-dimensional lattice whose sites may be either occupied or vacant, occupied sites become vacant at a constant rate and simultaneously cause all sites to the right to change their state. This random process exhibits rich phenomenology. First, there is a front, defined by the position of the leftmost occupied site, that propagates at a nontrivial velocity. Second, the front involves a depletion zone with an excess of vacant sites. The total excess {Delta}{sub k} increases logarithmically, {Delta}{sub k} {approx_equal}ln k, with the distance k from the front. Third, the front exhibits ageing -- young fronts are vigorous but old fronts are sluggish. We investigate these phenomena using a quasi-static approximation, direct solutions of small systems and numerical simulations.

  5. Reaction front formation in contaminant plumes.

    Science.gov (United States)

    Cribbin, Laura B; Winstanley, Henry F; Mitchell, Sarah L; Fowler, Andrew C; Sander, Graham C

    2014-12-15

    The formation of successive fronts in contaminated groundwater plumes by subsoil bacterial action is a commonly accepted feature of their propagation, but it is not obviously clear from a mathematical standpoint quite how such fronts are formed or propagate. In this paper we show that these can be explained by combining classical reaction-diffusion theory involving just two reactants (oxidant and reductant), and a secondary reaction in which a reactant on one side of such a front is (re-)formed on the other side of the front via diffusion of its product across the front. We give approximate asymptotic solutions for the reactant profiles, and the propagation rate of the front. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Lock-exchange experiments with an autocatalytic reaction front

    Science.gov (United States)

    Malham, I. Bou; Jarrige, N.; Martin, J.; Rakotomalala, N.; Talon, L.; Salin, D.

    2010-12-01

    A viscous lock-exchange gravity current corresponds to the reciprocal exchange of two fluids of different densities in a horizontal channel. The resulting front between the two fluids spreads as the square root of time, with a diffusion coefficient reflecting the buoyancy, viscosity, and geometrical configuration of the current. On the other hand, an autocatalytic reaction front between a reactant and a product may propagate as a solitary wave, namely, at a constant velocity and with a stationary concentration profile, resulting from the balance between molecular diffusion and chemical reaction. In most systems, the fluid left behind the front has a different density leading to a lock-exchange configuration. We revisit, with a chemical reaction, the classical situation of lock-exchange. We present an experimental analysis of buoyancy effects on the shape and the velocity of the iodate arsenous acid autocatalytic reaction fronts, propagating in horizontal rectangular channels and for a wide range of aspect ratios (1/3 to 20) and cylindrical tubes. We do observe stationary-shaped fronts, spanning the height of the cell and propagating along the cell axis. Our data support the contention that the front velocity and its extension are linked to each other and that their variations scale with a single variable involving the diffusion coefficient of the lock-exchange in the absence of chemical reaction. This analysis is supported by results obtained with lattice Bathnagar-Gross-Krook (BGK) simulations Jarrige et al. [Phys. Rev. E 81, 06631 (2010)], in other geometries (like in 2D simulations by Rongy et al. [J. Chem. Phys. 127, 114710 (2007)] and experiments in cylindrical tubes by Pojman et al. [J. Phys. Chem. 95, 1299 (1991)]), and for another chemical reaction Schuszter et al. [Phys. Rev. E 79, 016216 (2009)].

  7. Muon front end for the neutrino factory

    Directory of Open Access Journals (Sweden)

    C. T. Rogers

    2013-04-01

    Full Text Available In the neutrino factory, muons are produced by firing high-energy protons onto a target to produce pions. The pions decay to muons and pass through a capture channel known as the muon front end, before acceleration to 12.6 GeV. The muon front end comprises a variable frequency rf system for longitudinal capture and an ionization cooling channel. In this paper we detail recent improvements in the design of the muon front end.

  8. Atomic scale front propagation at the onset of frictional sliding.

    Science.gov (United States)

    Bonfanti, Silvia; Taloni, Alessandro; Negri, Carlotta; Sellerio, Alessandro; Manini, Nicola; Zapperi, Stefano

    2017-10-20

    Macroscopic frictional sliding emerges from atomic-scale interactions and processes at the contact interface, but bridging the gap between micro and macro scales still remains an unsolved challenge. Direct imaging of the contact surface and simultaneous measurement of stress fields during macroscopic frictional slip revealed the formation of crack precursors, questioning the traditional picture of frictional contacts described in terms of a single degree of freedom. Here we study the onset of frictional slip at atomic scale by simulating the motion of an aluminum block pushed by a slider on a copper substrate. We show the formation of dynamic slip front propagation and precursory activity that resemble macroscopic observations. The analysis of stress patterns during slip, however, reveals subtle effects due to the lattice structures which hinder a direct application of linear elastic fracture mechanics. Our results illustrate that dynamic front propagation arises already at the atomic scales and shed light on the connections between atomic-scale and macroscopic friction.

  9. Consumer preferences for front-of-pack calories labelling.

    Science.gov (United States)

    van Kleef, Ellen; van Trijp, Hans; Paeps, Frederic; Fernández-Celemín, Laura

    2008-02-01

    In light of the emerging obesity pandemic, front-of-pack calories labels may be an important tool to assist consumers in making informed healthier food choices. However, there is little prior research to guide key decisions on whether caloric content should be expressed in absolute terms or relative to recommended daily intake, whether it should be expressed in per serving or per 100 g and whether the information should be further brought alive for consumers in terms of what the extra calorie intake implies in relation to activity levels. The present study aimed at providing more insight into consumers' appreciation of front-of-pack labelling of caloric content of food products and their specific preferences for alternative execution formats for such information in Europe. For this purpose, eight executions of front-of-pack calorie flags were designed and their appeal and information value were extensively discussed with consumers through qualitative research in four different countries (Germany, The Netherlands, France and the UK). The results show that calories are well-understood and that participants were generally positive about front-of-pack flags, particularly when flags are uniform across products. The most liked flags are the simpler flags depicting only the number of calories per serving or per 100 g, while more complex flags including references to daily needs or exercise and the flag including a phrase referring to balanced lifestyle were least preferred. Some relevant differences between countries were observed. Although participants seem to be familiar with the notion of calories, they do not seem to fully understand how to apply them. From the results, managerial implications for the design and implementation of front-of-pack calorie labelling as well as important directions for future research are discussed.

  10. Consumer preferences for front-of-pack calories labelling

    Science.gov (United States)

    van Kleef, Ellen; van Trijp, Hans; Paeps, Frederic; Fernández-Celemín, Laura

    2008-01-01

    Objective In light of the emerging obesity pandemic, front-of-pack calories labels may be an important tool to assist consumers in making informed healthier food choices. However, there is little prior research to guide key decisions on whether caloric content should be expressed in absolute terms or relative to recommended daily intake, whether it should be expressed in per serving or per 100 g and whether the information should be further brought alive for consumers in terms of what the extra calorie intake implies in relation to activity levels. The present study aimed at providing more insight into consumers’ appreciation of front-of-pack labelling of caloric content of food products and their specific preferences for alternative execution formats for such information in Europe. Design For this purpose, eight executions of front-of-pack calorie flags were designed and their appeal and information value were extensively discussed with consumers through qualitative research in four different countries (Germany, The Netherlands, France and the UK). Results The results show that calories are well-understood and that participants were generally positive about front-of-pack flags, particularly when flags are uniform across products. The most liked flags are the simpler flags depicting only the number of calories per serving or per 100 g, while more complex flags including references to daily needs or exercise and the flag including a phrase referring to balanced lifestyle were least preferred. Some relevant differences between countries were observed. Although participants seem to be familiar with the notion of calories, they do not seem to fully understand how to apply them. Conclusion From the results, managerial implications for the design and implementation of front-of-pack calorie labelling as well as important directions for future research are discussed. PMID:17601362

  11. Front blind spot crashes in Hong Kong.

    Science.gov (United States)

    Cheng, Yuk Ki; Wong, Koon Hung; Tao, Chi Hang; Tam, Cheok Ning; Tam, Yiu Yan; Tsang, Cheuk Nam

    2016-09-01

    In 2012-2014, our laboratory had investigated a total of 9 suspected front blind spot crashes, in which the medium and heavy goods vehicles pulled away from rest and rolled over the pedestrians, who were crossing immediately in front of the vehicles. The drivers alleged that they did not see any pedestrians through the windscreens or the front blind spot mirrors. Forensic assessment of the goods vehicles revealed the existence of front blind spot zones in 3 out of these 9 accident vehicles, which were attributed to the poor mirror adjustments or even the absence of a front blind spot mirror altogether. In view of this, a small survey was devised involving 20 randomly selected volunteers and their goods vehicles and 5 out of these vehicles had blind spots at the front. Additionally, a short questionnaire was conducted on these 20 professional lorry drivers and it was shown that most of them were not aware of the hazards of blind spots immediately in front of their vehicles, and many did not use the front blind spot mirrors properly. A simple procedure for quick measurements of the coverage of front blind spot mirrors using a coloured plastic mat with dimensional grids was also introduced and described in this paper. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

  12. Analyzing luminescent solar concentrators with front-facing photovoltaic cells using weighted Monte Carlo ray tracing

    Science.gov (United States)

    Woei Leow, Shin; Corrado, Carley; Osborn, Melissa; Isaacson, Michael; Alers, Glenn; Carter, Sue A.

    2013-06-01

    Luminescent solar concentrators (LSC) collect ambient light from a broad range of angles and concentrate the captured light onto photovoltaic (PV) cells. LSCs with front-facing cells collect direct and indirect sunlight ensuring a gain factor greater than one. The flexible placement and percentage coverage of PV cells on the LSC panel allow for layout adjustments to be made in order to balance re-absorption losses and the level of light concentration desired. A weighted Monte Carlo ray tracing program was developed to study the transport of photons and loss mechanisms in the LSC to aid in design optimization. The program imports measured absorption/emission spectra of an organic luminescent dye (LR305), the transmission coefficient, and refractive index of acrylic as parameters that describe the system. Simulations suggest that for LR305, 8-10 cm of luminescent material surrounding the PV cell yields the highest increase in power gain per unit area of LSC added, thereby determining the ideal spacing between PV cells in the panel. For rectangular PV cells, results indicate that for each centimeter of PV cell width, an additional increase of 0.15 mm to the waveguide thickness is required to efficiently transport photon collected by the LSC to the PV cell with minimal loss.

  13. Traveling interface modulations and anisotropic front propagation in ammonia oxidation over Rh(110)

    Energy Technology Data Exchange (ETDEWEB)

    Rafti, Matías [Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Fac. Cs. Exactas, Universidad Nacional de La Plata, 64 y Diag. 113 (1900), La Plata (Argentina); Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstr. 3-3a, D-30167 Hannover (Germany); Borkenhagen, Benjamin; Lilienkamp, Gerhard [Institut für Energieforschung und Physikalische Technologien, Technische Universität Clausthal, Leibnizstr. 4, 38678 Clausthal-Zellerfeld (Germany); Lovis, Florian; Smolinsky, Tim; Imbihl, Ronald, E-mail: imbihl@pci.uni-hannvover.de [Institut für Physikalische Chemie und Elektrochemie, Leibniz-Universität Hannover, Callinstr. 3-3a, D-30167 Hannover (Germany)

    2015-11-14

    The bistable NH{sub 3} + O{sub 2} reaction over a Rh(110) surface was explored in the pressure range 10{sup −6}–10{sup −3} mbar and in the temperature range 300–900 K using photoemission electron microscopy and low energy electron microscopy as spatially resolving methods. We observed a history dependent anisotropy in front propagation, traveling interface modulations, transitions with secondary reaction fronts, and stationary island structures.

  14. Color light-emitting diode reflection topography: validation of keratometric repeatability in a large sample of wide cylindrical-range corneas.

    Science.gov (United States)

    Kanellopoulos, Anastasios John; Asimellis, George

    2015-01-01

    To investigate repeatability of steep and flat keratometry measurements, as well as astigmatism axis in cohorts with normal range and regular astigmatic such as: eyes following laser-assisted in situ keratomileusis (LASIK) and normal population, as well as cohorts of high and irregular astigmatism such as keratoconic eyes, and keratoconic eyes following corneal collagen cross-linking, employing a novel corneal reflection topography device. Steep and flat keratometry and astigmatism axis measurement repeatability was investigated employing a novel multicolored-spot reflection topographer (Cassini) in four study groups, namely a post myopic LASIK-treated Group A, a keratoconus Group B, a post-CXL keratoconus Group C, and a control Group D of routine healthy patients. Three separate, maps were obtained employing the Cassini, enabling investigation of the intra-individual repeatability by standard deviation. Additionally we investigated in all groups,the Klyce surface irregularity indices for keratoconus, the SAI (surface asymmetry index) and the SRI (surface regularity index). Flat keratometry repeatability was 0.74±0.89 (0.03 to 5.26) diopters (D) in the LASIK Group A, 0.88±1.45 (range minimum to maximum, 0.00 to 7.84) D in the keratoconic Group B, and 0.71±0.94 (0.02 to 6.23) D in the cross-linked Group C. The control Group D had flat keratometry repeatability 0.36±0.46 (0.00 to 2.71) D. Steep keratometry repeatability was 0.64±0.82 (0.01 to 4.81) D in the LASIK Group A, 0.89±1.22 (0.02 to 7.85) D in the keratoconic Group B, and 0.93±1.12 (0.04 to 5.93) D in the cross-linked Group C. The control Group D had steep keratometry repeatability 0.41±0.50 (0.00 to 3.51) D. Axis repeatability was 3.45±1.62° (0.38 to 7.78°) for the LASIK Group A, 4.12±3.17° (0.02 to 12.13°) for the keratoconic Group B, and 3.20±1.99° (0.17 to 8.61°) for the cross-linked Group C. The control Group D had axis repeatability 2.16±1.39° (0.05 to 5.86°). The SAI index

  15. The Front-End System For MARE In Milano

    Science.gov (United States)

    Arnaboldi, Claudio; Pessina, Gianluigi

    2009-12-01

    The first phase of MARE consists of 72 μ-bolometers composed each of a crystal of AgReO4 readout by Si thermistors. The spread in the thermistor characteristics and bolometer thermal coupling leads to different energy conversion gains and optimum operating points of the detectors. Detector biasing levels and voltage gains are completely remote-adjustable by the front end system developed, the subject of this paper, achieving the same signal range at the input of the DAQ system. The front end consists of a cold buffer stage, a second pseudo differential stage followed by a gain stage, an antialiasing filter, and a battery powered detector biasing set up. The DAQ system can be used to set all necessary parameters of the electronics remotely, by writing to a μ-controller located on each board. Fiber optics are used for the serial communication between the DAQ and the front end. To suppress interference noise during normal operation, the clocked devices of the front end are maintained in sleep-mode, except during the set-up phase of the experiment. An automatic DC detector characterization procedure is used to establish the optimum operating point of every detector of the array. A very low noise level has been achieved: about 3nV/□Hz at 1 Hz and 1 nV/□Hz for the white component, high frequencies.

  16. Propulsive force in front crawl swimming

    NARCIS (Netherlands)

    Berger, M.A.M.; de Groot, G.; Hollander, A.P.

    1999-01-01

    To evaluate the propulsive forces in front crawl arm swimming, derived from a three-dimensional kinematic analysis, these values were compared with mean drag forces. The propulsive forces during front crawl swimming using the arms only were calculated using three-dimensional kinematic analysis

  17. Through the EU's Back and Front Doors

    DEFF Research Database (Denmark)

    Adler-Nissen, Rebecca

    2015-01-01

    Through the EU's front- and backdoors: The selective Danish and Norwegian approaches in the Area of Freedom, Security and Justice Rebecca Adler-Nissen......Through the EU's front- and backdoors: The selective Danish and Norwegian approaches in the Area of Freedom, Security and Justice Rebecca Adler-Nissen...

  18. Coping on the Front-line

    DEFF Research Database (Denmark)

    Sanden, Guro Refsum; Lønsmann, Dorte

    This article investigates how front-line employees respond to English language policies implemented by the management of three multinational corporations (MNCs) headquartered in Scandinavia. Based on interview and document data the article examines the ways in which front-line employees cross lan...

  19. Thermal Fronts Atlas of Canadian Coastal Waters

    NARCIS (Netherlands)

    Cyr, F.; Larouche, P.

    2015-01-01

    Oceanic fronts are often associated with enhanced biological activity. Depending on their generation mechanism, they are often linked to specific geographical areas. Here we use 25 years of high-resolution satellite sea surface temperature (SST) daily images to generate maps of SST fronts over

  20. End-Users, Front Ends and Librarians.

    Science.gov (United States)

    Bourne, Donna E.

    1989-01-01

    The increase in end-user searching, the advantages and limitations of front ends, and the role of the librarian in end-user searching are discussed. It is argued that librarians need to recognize that front ends can be of benefit to themselves and patrons, and to assume the role of advisors and educators for end-users. (37 references) (CLB)

  1. Turbulence spectra measured during fire front passage

    Science.gov (United States)

    Daisuke Seto; Craig B. Clements; Warren E. Heilman

    2013-01-01

    Four field experiments were conducted over various fuel and terrain to investigate turbulence generation during the passage of wildland fire fronts. Our results indicate an increase in horizontal mean winds and friction velocity, horizontal and vertical velocity variances as well as a decreased degree of anisotropy in TKE during fire front passage (FFP) due to fire-...

  2. Color light-emitting diode reflection topography: validation of keratometric repeatability in a large sample of wide cylindrical-range corneas

    Directory of Open Access Journals (Sweden)

    Kanellopoulos AJ

    2015-02-01

    Full Text Available Anastasios John Kanellopoulos,1,2 George Asimellis11LaserVision.gr Clinical and Research Eye Institute, Athens, Greece; 2New York University Medical School, New York, NY, USAPurpose: To investigate repeatability of steep and flat keratometry measurements, as well as astigmatism axis in cohorts with normal range and regular astigmatic such as: eyes following laser-assisted in situ keratomileusis (LASIK and normal population, as well as cohorts of high and irregular astigmatism such as keratoconic eyes, and keratoconic eyes following corneal collagen cross-linking, employing a novel corneal reflection topography device.Methods: Steep and flat keratometry and astigmatism axis measurement repeatability was investigated employing a novel multicolored-spot reflection topographer (Cassini in four study groups, namely a post myopic LASIK-treated Group A, a keratoconus Group B, a post-CXL keratoconus Group C, and a control Group D of routine healthy patients. Three separate, maps were obtained employing the Cassini, enabling investigation of the intra-individual repeatability by standard deviation. Additionally we investigated in all groups,the Klyce surface irregularity indices for keratoconus, the SAI (surface asymmetry index and the SRI (surface regularity index.Results: Flat keratometry repeatability was 0.74±0.89 (0.03 to 5.26 diopters (D in the LASIK Group A, 0.88±1.45 (range minimum to maximum, 0.00 to 7.84 D in the keratoconic Group B, and 0.71±0.94 (0.02 to 6.23 D in the cross-linked Group C. The control Group D had flat keratometry repeatability 0.36±0.46 (0.00 to 2.71 D. Steep keratometry repeatability was 0.64±0.82 (0.01 to 4.81 D in the LASIK Group A, 0.89±1.22 (0.02 to 7.85 D in the keratoconic Group B, and 0.93±1.12 (0.04 to 5.93 D in the cross-linked Group C. The control Group D had steep keratometry repeatability 0.41±0.50 (0.00 to 3.51 D. Axis repeatability was 3.45±1.62° (0.38 to 7.78° for the LASIK Group A, 4.12±3.17

  3. Taxonomy of Greater White-fronted Geese (Aves: Anatidae)

    Science.gov (United States)

    Banks, Richard C.

    2011-01-01

    Five subspecies of the Greater White-fronted Goose, Anser albifrons (Scopoli, 1769), have been named, all on the basis of wintering birds, and up to six subspecies have been recognized. There has been confusion over the application of some names, particularly in North America, because of lack of knowledge of the breeding ranges and type localities, and incorrect taxonomic decisions. There is one clinally varying subspecies in Eurasia, one that breeds in Greenland, and three in North America, one newly named herein.

  4. Coherent structures for front propagation in fluids

    Science.gov (United States)

    Mitchell, Kevin; Mahoney, John

    2014-03-01

    Our goal is to characterize the nature of reacting flows by identifying important ``coherent'' structures. We follow the recent work by Haller, Beron-Vera, and Farazmand which formalized the notion of lagrangian coherent structures (LCSs) in fluid flows. In this theory, LCSs were derived from the Cauchy-Green strain tensor. We adapt this perspective to analogously define coherent structures in reacting flows. By this we mean a fluid flow with a reaction front propagating through it such that the propagation does not affect the underlying flow. A reaction front might be chemical (Belousov-Zhabotinsky, flame front, etc.) or some other type of front (electromagnetic, acoustic, etc.). While the recently developed theory of burning invariant manifolds (BIMs) describes barriers to front propagation in time-periodic flows, this current work provides an important complement by extending to the aperiodic setting. Funded by NSF Grant CMMI-1201236.

  5. Microscopic Mechanisms for Propagating Deformation Fronts

    Science.gov (United States)

    Franklin, Scott

    2001-03-01

    Alloys often deform through the propagation of slowly moving ( cm/s) fronts separating strained and unstrained regions. Theories for these Portevin-Le Chatelier (PLC) fronts are mostly on the macroscopic level, dealing with strains instead of dislocation populations. In these models diffusion, a possible mechanism for propagation, fails to produce front behavior consistent with experiments. Previous work* used a nonlocal strain-rate to successfully reproduce many different aspects of experimentally observed fronts. Ananthakrishna has proposed a set of equations that describe the evolution of different dislocation populations. These equations reproduce the temporal behavior of the PLC effect, serrated stress-strain curves accompanying smooth loading. It is natural to ask whether diffusive or other spatial coupling terms added to this model result in fronts. I will discuss simulations of these equations with added spatial terms and attempt to compare the results with experiments. *S. Franklin, F. Mertens, and M. Marder, Phys. Rev. E V. 62 (2000)

  6. Ultra-wideband wireless receiver front-end for high-speed indoor applications

    Directory of Open Access Journals (Sweden)

    Zhe-Yang Huang

    2014-12-01

    Full Text Available Low-noise, ultra-wideband (UWB wireless receiver front-end circuits were presented in this study. A two-stage common-source low-noise amplifier with wideband input impedance matching network, an active-balun and a double-balanced down-conversion mixer were adopted in the UWB wireless receiver front-end. The proposed wireless receiver front-end circuits were implemented in 0.18 μm radio-frequency-CMOS process. The maximum down-conversion power gain of the front-end is 25.8 dB; minimum single-sideband noise figure of the front-end is 4.9 dB over complete UWB band ranging from 3.1 to 10.6 GHz. Power consumption including buffers is 39.2 mW.

  7. Smart brake light system would provide more information to drivers

    OpenAIRE

    Trulove, Susan

    2008-01-01

    You are driving in heavy traffic. The brake lights on the car in front of you come on. Is the car slowing or is it going to stop? It slows to 25 mph and the lights go off. You drop back. The car in front of you stops suddenly! You stop just in time. The car behind you collects your rear bumper.

  8. Dependence of wave front refraction on pupil size due to the presence of higher order aberrations.

    Science.gov (United States)

    Iseli, H P; Bueeler, M; Hafezi, F; Seiler, T; Mrochen, M

    2005-01-01

    Propagation of light through the optical pathway within the eye can lead to a deformation of the wave front that might affect objective but also subjective refraction depending on pupil size. The aim of this study was to investigate the change in wave front refraction that is calculated on the basis of second order Zernike polynomials when varying the pupil size from 6 mm to 3 mm. The change was correlated with the amount of fourth and sixth order spherical aberration and fourth and sixth order astigmatism. Wave front aberrations were measured in 130 eyes by means of a Tscherning wave front sensor at a pupil size of 6 mm. Wave front aberrations in terms of Zernike coefficients up to sixth order were approximated for 6 mm and 3 mm pupil size. The wave front refraction was calculated based on the second order Zernike coefficients for both pupil diameters. Resulting differences in wave front refraction (sphere or cylinder) due to the change in pupil size were correlated with the initial higher order aberrations determined for the 6.0 mm pupil by means of a linear regression (Spearman rank correlation coefficient). The correlation between the change in sphere and cylinder on one hand and the spherical aberration and higher order astigmatism on the other hand was found to be highly significant (ppupil size should be established in the ophthalmic community.

  9. Mixed quantum/classical calculations of total and differential elastic and rotationally inelastic scattering cross sections for light and heavy reduced masses in a broad range of collision energies.

    Science.gov (United States)

    Semenov, Alexander; Babikov, Dmitri

    2014-01-28

    The mixed quantum/classical theory (MQCT) for rotationally inelastic scattering developed recently [A. Semenov and D. Babikov, J. Chem. Phys. 139, 174108 (2013)] is benchmarked against the full quantum calculations for two molecular systems: He + H2 and Na + N2. This allows testing new method in the cases of light and reasonably heavy reduced masses, for small and large rotational quanta, in a broad range of collision energies and rotational excitations. The resultant collision cross sections vary through ten-orders of magnitude range of values. Both inelastic and elastic channels are considered, as well as differential (over scattering angle) cross sections. In many cases results of the mixed quantum/classical method are hard to distinguish from the full quantum results. In less favorable cases (light masses, larger quanta, and small collision energies) some deviations are observed but, even in the worst cases, they are within 25% or so. The method is computationally cheap and particularly accurate at higher energies, heavier masses, and larger densities of states. At these conditions MQCT represents a useful alternative to the standard full-quantum scattering theory.

  10. Transmural anoxic wave front and regional dysfunction during early ischemia.

    Science.gov (United States)

    Kanaide, H; Taira, Y; Nakamura, M

    1987-08-01

    The relative time courses of early changes in myocardial metabolism and function during anoxia, global ischemia, and regional ischemia were compared in isolated rat hearts. Transmural anoxic wave front was determined with NADH fluorescence photography, and oxygen saturation of myoglobin and dynamic systolic wall thickening were measured with spectrophotometry of light transmitted through the left ventricular free wall. In all three treatments, anoxic wave front first appeared in the subendocardium and reached the epicardial half of the myocardium in 10 s, when oxygen saturation of myoglobin decreased by 50% and tissue ATP and creatine phosphate remained at aerobic levels. During this period, systolic wall thickening decreased gradually in anoxia and global ischemia, whereas a marked decrease in systolic wall thickening and appearance of dyskinesia (wall thinning) occurred in regional ischemia. Thus the early extension of anoxic wave front and metabolic changes are similar with all three treatments, and dyskinesia, observed only in case of regional ischemia, occurs when the inner half is ischemic or anoxic.

  11. Digital front-end module (DFEM) series; Digital front end module (DFEM) series

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    The digital front-end module (DFEM) is a module in which the processes ranging from the reception of digitally modulated radiofrequencies to the output of digital IF (Intermediate Frequency) signals or data streams are integrated. Beginning with a module for the MCNS (Multimedia Cable Network System) cable modem which was the first module in this business field approved by the Cable Labs, U.S., Toshiba has developed a series of DFEMs for various digital media for satellites, ground waves, and CATV (Cable Television) systems. The series is characterized by (1) the serialization of DFEMs compatible with various digital modulation techniques such as 8 PSK (Phase Shift Keying), OFDM (Orthogonal Frequency Division Multiplexing), and 256 QAM (Quadrature Amplitude Modulation), (2) easy connection with digital circuits thanks to the high shielding effect, and (3) the achievement of smaller size, higher performance, and lower power consumption. (translated by NEDO)

  12. Io in Front of Jupiter

    Science.gov (United States)

    2000-01-01

    Jupiter's four largest satellites, including Io, the golden ornament in front of Jupiter in this image from NASA's Cassini spacecraft, have fascinated Earthlings ever since Galileo Galilei discovered them in 1610 in one of his first astronomical uses of the telescope.Images from Cassini that will be released over the next several days capture each of the four Galilean satellites in their orbits around the giant planet.This true-color composite frame, made from narrow angle images taken on Dec. 12, 2000, captures Io and its shadow in transit against the disk of Jupiter. The distance of the spacecraft from Jupiter was 19.5 million kilometers (12.1 million miles). The image scale is 117 kilometers (73 miles) per pixel.The entire body of Io, about the size of Earth's Moon, is periodically flexed as it speeds around Jupiter and feels, as a result of its non-circular orbit, the periodically changing gravitational pull of the planet. The heat arising in Io's interior from this continual flexure makes it the most volcanically active body in the solar system, with more than 100 active volcanoes. The white and reddish colors on its surface are due to the presence of different sulfurous materials. The black areas are silicate rocks.Cassini is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the Cassini mission for NASA's Office of Space Science, Washington, D.C.

  13. Blocking-resistant communication through domain fronting

    Directory of Open Access Journals (Sweden)

    Fifield David

    2015-06-01

    Full Text Available We describe “domain fronting,” a versatile censorship circumvention technique that hides the remote endpoint of a communication. Domain fronting works at the application layer, using HTTPS, to communicate with a forbidden host while appearing to communicate with some other host, permitted by the censor. The key idea is the use of different domain names at different layers of communication. One domain appears on the “outside” of an HTTPS request—in the DNS request and TLS Server Name Indication—while another domain appears on the “inside”—in the HTTP Host header, invisible to the censor under HTTPS encryption. A censor, unable to distinguish fronted and nonfronted traffic to a domain, must choose between allowing circumvention traffic and blocking the domain entirely, which results in expensive collateral damage. Domain fronting is easy to deploy and use and does not require special cooperation by network intermediaries. We identify a number of hard-to-block web services, such as content delivery networks, that support domain-fronted connections and are useful for censorship circumvention. Domain fronting, in various forms, is now a circumvention workhorse. We describe several months of deployment experience in the Tor, Lantern, and Psiphon circumvention systems, whose domain-fronting transports now connect thousands of users daily and transfer many terabytes per month.

  14. Embodied Energy and Off-Grid Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Alstone, Peter; Mills, Evan; Jacobson, Arne

    2011-01-25

    The greenhouse gas (GHG) emissions from fuel-based lighting are substantial given the paltry levels of lighting service provided to users, leading to a great opportunity for GHG mitigation byencouraging the switch from fuel-based to rechargeable LED lighting. However, as with most new energy technology, switching to efficient lighting requires an up-front investment of energy(and GHGs) embedded in the manufacture of replacement components. We studied a population of off-grid lighting users in 2008-2009 in Kenya who were given the opportunity to adopt LEDlighting. Based on their use patterns with the LED lights and the levels of kerosene offset we observed, we found that the embodied energy of the LED lamp was"paid for" in only one month for grid charged products and two months for solar charged products. Furthermore, the energyreturn-on investment-ratio (energy produced or offset over the product's service life divided by energy embedded) for off-grid LED lighting ranges from 12 to 24, which is on par with on-gridsolar and large-scale wind energy. We also found that the energy embodied in the manufacture of a typical hurricane lantern is about one-half to one-sixth of that embodied in the particular LEDlights that we evaluated, indicating that the energy payback time would be moderately faster if LEDs ultimately displace the production of kerosene lanterns. As LED products improve, weanticipate longer service lives and more successful displacement of kerosene lighting, both of which will speed the already rapid recovery of embodied energy in these products. Our studyprovides a detailed appendix with embodied energy values for a variety of components used to construct off-grid LED lighting, which can be used to analyze other products.

  15. Ultrashort-pulse wave-front autocorrelation.

    Science.gov (United States)

    Grunwald, R; Neumann, U; Griebner, U; Reimann, K; Steinmeyer, G; Kebbel, V

    2003-12-01

    Combined spatially resolved collinear autocorrelation and Shack-Hartmann wave-front sensing of femtosecond laser pulses is demonstrated for the first time to our knowledge. The beam is divided into multiple nondiffracting subbeams by thin-film micro-optical arrays. With hybrid refractive-reflective silica/silver microaxicons, wave-front autocorrelation is performed in oblique-angle reflection. Simultaneous two-dimensional detection of local temporal structure and wave-front tilt of propagating few-cycle wave packets is demonstrated.

  16. Pressure transient method for front tracking

    Energy Technology Data Exchange (ETDEWEB)

    Benson, S.M.; Bodvarsson, G.S.

    1983-08-01

    A pressure transient technique for tracking the advance of cold water fronts during water flooding and goethermal injection operations has been developed. The technique is based on the concept that the steady state pressure buildup in the reservoir region inside the front can be calculated by a fluid skin factor. By analyzing successive pressure falloff tests, the advance of the front in the reservoir can be monitored. The validity of the methods is demonstrated by application to three numerically simulated data sets, a nonisothermal step-rate injection test, a series of pressure falloffs in a multilayered reservoir, and a series of pressure falloff tests in a water flooded oil reservoir.

  17. Frontón en Lezkairu

    OpenAIRE

    Legarra Arizaleta, Xabier

    2010-01-01

    El objetivo del proyecto es el diseño, cálculo y presupuestado de un frontón cubierto de 36 metros de longitud, con sus correspondientes gradas, instalaciones y aparcamientos en el nuevo barrio pamplonés de Lezkairu. El frontón propuesto está destinado a un uso público debido a la gran demanda que nace en relación a la pelota, y sus diferentes modalidades así como la carencia de más infraestructuras de este tipo. Cabe destacar que las características y medidas del frontón lo ...

  18. Automated reconstruction of neural trees using front re-initialization

    Science.gov (United States)

    Mukherjee, Amit; Stepanyants, Armen

    2012-02-01

    This paper proposes a greedy algorithm for automated reconstruction of neural arbors from light microscopy stacks of images. The algorithm is based on the minimum cost path method. While the minimum cost path, obtained using the Fast Marching Method, results in a trace with the least cumulative cost between the start and the end points, it is not sufficient for the reconstruction of neural trees. This is because sections of the minimum cost path can erroneously travel through the image background with undetectable detriment to the cumulative cost. To circumvent this problem we propose an algorithm that grows a neural tree from a specified root by iteratively re-initializing the Fast Marching fronts. The speed image used in the Fast Marching Method is generated by computing the average outward flux of the gradient vector flow field. Each iteration of the algorithm produces a candidate extension by allowing the front to travel a specified distance and then tracking from the farthest point of the front back to the tree. Robust likelihood ratio test is used to evaluate the quality of the candidate extension by comparing voxel intensities along the extension to those in the foreground and the background. The qualified extensions are appended to the current tree, the front is re-initialized, and Fast Marching is continued until the stopping criterion is met. To evaluate the performance of the algorithm we reconstructed 6 stacks of two-photon microscopy images and compared the results to the ground truth reconstructions by using the DIADEM metric. The average comparison score was 0.82 out of 1.0, which is on par with the performance achieved by expert manual tracers.

  19. Role of weighting in the dynamics of front propagation

    Energy Technology Data Exchange (ETDEWEB)

    Zekri, Nouredine, E-mail: zekri@univ-usto.dz [Université des Sciences et de la Technologie d' Oran Mohamed Boudiaf, Département de Physique, LEPM, BP 1505 El Mnaouer, Oran (Algeria); Khelloufi, Khadidja; Zekri, Lotfi [Université des Sciences et de la Technologie d' Oran Mohamed Boudiaf, Département de Physique, LEPM, BP 1505 El Mnaouer, Oran (Algeria); Porterie, Bernard; Kaiss, Ahmed; Clerc, Jean-Pierre [Aix-Marseille Université, CNRS, IUSTI UMR 7343, 13453, Marseille (France)

    2012-07-30

    Non-equilibrium front propagation in a two-dimensional network modelling wildfire propagation was studied. The model includes deterministic long-range interactions due to radiation and a time weighting procedure. Three weight-dependent propagation regimes were found: dynamical, static, and non-propagative. The dynamical regime shows saturation for small weight values and a percolation transition area depending on the weight and size of the interaction domain. From the scaling interface exponents, the model seems to belong to the dynamical percolation universality class. In the limit of static regime it belongs to the random deposition class. -- Highlights: ► Percolation model used includes the weighting procedure and long-range interactions (an interaction domain). The interaction strength is chosen to decrease inversely with the square distance. ► There is a weight threshold R{sub c} above which the front cannot propagate. ► At R{sub c} the percolation is static (usual percolation), and below this threshold it becomes dynamic. ► A generalized dependence of the percolation threshold on both the interaction size n{sub y} and the weight parameter R is proposed. ► A further study of the front dynamic scaling is added to this version and dynamic exponents determined.

  20. Building Blocks for a 24 GHz Phased-Array Front-End in CMOS Technology for Smart Streetlights

    OpenAIRE

    Ban Wang; Gabriele Tasselli; Cyril Botteron; Pierr-André Farine

    2014-01-01

    According to a recent European Union report lighting represents a significant share of electricity costs and the goal of reducing lighting power consumption by 20 demands the coupling of light emitting diode (LED) lights with smart sensors and communication networks. This paper proposes the integration of these three elements into a smart streetlight which is based on LEDs and a 24 GHz phased array (Ph A) front end (FE) designed in low cost 90nm complementary metal oxide semiconductor (CMOS) ...

  1. Front-end electronics for the CMS preshower detector

    CERN Document Server

    Go, A; Barney, D; Bloch, P; Peisert, Anna; Löfstedt, B; Reynaud, S; Borkar, S; Lalwani, S

    2002-01-01

    The front-end readout system PACE2 for the CMS preshower detector consists of two chips: Delta is a 32 channel preamplifier and shaper that provides low noise, charge to voltage readout for large capacitive silicon sensors over a large dynamic range (up to 400 MIPs); PACE-AM contains a 32-channel wide, 160-cell deep, analog memory with a 32 to 1 multiplexer for serial readout. These chips are designed in .8 mu m BiCMOS DMILL radiation tolerant technology. The performance in terms of dynamic range, linearity, noise, peaking time and memory uniformity are presented. (4 refs).

  2. Properties of Deflagration Fronts and Models for Type IA Supernovae

    Science.gov (United States)

    Domínguez, I.; Höflich, P.

    2000-01-01

    Detailed models of the explosion of a white dwarf that include self-consistent calculations of the light curve and spectra provide a link between observational quantities and the underlying explosion model. These calculations assume spherical geometry and are based on parameterized descriptions of the burning front. Recently, the first multidimensional calculations for nuclear burning fronts have been performed. Although a fully consistent treatment of the burning fronts is beyond the current state of the art, these calculations provide a new and better understanding of the physics. Several new descriptions for flame propagation have been proposed by Khokhlov et al. and Niemeyer et al. Using various descriptions for the propagation of a nuclear deflagration front, we have studied the influence on the results of previous analyses of Type Ia supernovae, namely, the nucleosynthesis and structure of the expanding envelope. Our calculations are based on a set of delayed detonation models with parameters that give a good account of the optical and infrared light curves and of the spectral evolution. In this scenario, the burning front first propagates in a deflagration mode and subsequently turns into a detonation. The explosions and light curves are calculated using a one-dimensional Lagrangian radiation-hydro code including a detailed nuclear network. We find that the results of the explosion are rather insensitive to details of the description of the deflagration front, even if its speed and the time from the transition to detonation differ almost by a factor of 2. For a given white dwarf (WD) and a fixed transition density, the total production of elements changes by less than 10%, and the distribution in the velocity space changes by less than 7%. Qualitatively, this insensitivity of the final outcome of the explosion to the details of the flame propagation during the (slow) deflagration phase can be understood as follows: for plausible variations in the speed of

  3. Metamaterial Huygens' surfaces: tailoring wave fronts with reflectionless sheets.

    Science.gov (United States)

    Pfeiffer, Carl; Grbic, Anthony

    2013-05-10

    Huygens' principle is a well-known concept in electromagnetics that dates back to 1690. Here, it is applied to develop designer surfaces that provide extreme control of electromagnetic wave fronts across electrically thin layers. These reflectionless surfaces, referred to as metamaterial Huygens' surfaces, provide new beam shaping, steering, and focusing capabilities. The metamaterial Huygens' surfaces are realized with two-dimensional arrays of polarizable particles that provide both electric and magnetic polarization currents to generate prescribed wave fronts. A straightforward design methodology is demonstrated and applied to develop a beam-refracting surface and a Gaussian-to-Bessel beam transformer. Metamaterial Huygens' surfaces could find a wide range of applications over the entire electromagnetic spectrum including single-surface lenses, polarization controlling devices, stealth technologies, and perfect absorbers.

  4. Flexible Frequency Discrimination Subsystems for Reconfigurable Radio Front Ends

    Directory of Open Access Journals (Sweden)

    Carey-Smith Bruce E.

    2005-01-01

    Full Text Available The required flexibility of the software-defined radio front end may currently be met with better overall performance by employing tunable narrowband circuits rather than pursuing a truly wideband approach. A key component of narrowband transceivers is appropriate filtering to reduce spurious spectral content in the transmitter and limit out-of-band interference in the receiver. In this paper, recent advances in flexible, frequency-selective, circuit components applicable to reconfigurable SDR front ends are reviewed. The paper contains discussion regarding the filtering requirements in the SDR context and the use of intelligent, adaptive control to provide environment-aware frequency discrimination. Wide tuning-range frequency-selective circuit elements are surveyed including bandpass and bandstop filters and narrowband tunable antennas. The suitability of these elements to the mobile wireless SDR environment is discussed.

  5. Front dynamics in fractional-order epidemic models.

    Science.gov (United States)

    Hanert, Emmanuel; Schumacher, Eva; Deleersnijder, Eric

    2011-06-21

    A number of recent studies suggest that human and animal mobility patterns exhibit scale-free, Lévy-flight dynamics. However, current reaction-diffusion epidemics models do not account for the superdiffusive spread of modern epidemics due to Lévy flights. We have developed a SIR model to simulate the spatial spread of a hypothetical epidemic driven by long-range displacements in the infective and susceptible populations. The model has been obtained by replacing the second-order diffusion operator by a fractional-order operator. Theoretical developments and numerical simulations show that fractional-order diffusion leads to an exponential acceleration of the epidemic's front and a power-law decay of the front's leading tail. Our results indicate the potential of fractional-order reaction-diffusion models to represent modern epidemics. Copyright © 2011 Elsevier Ltd. All rights reserved.

  6. A digital Front-End and Readout MIcrosystem for calorimetry at LHC

    CERN Multimedia

    2002-01-01

    % RD-16 A Digital Front-End and Readout Microsystem for Calorimetry at LHC \\\\ \\\\Front-end signal processing for calorimetric detectors is essential in order to achieve adequate selectivity in the trigger function of an LHC experiment, with data identification and compaction before readout being required in the harsh, high rate environment of a high luminosity hadron machine. Other crucial considerations are the extremely wide dynamic range and bandwidth requirements, as well as the volume of data to be transferred to following stages of the trigger and readout system. These requirements are best met by an early digitalization of the detector information, followed by integrated digital signal processing and buffering functions covering the trigger latencies.\\\\ \\\\The FERMI (Front-End Readout MIcrosystem) is a digital implementation of the front-end and readout electronic chain for calorimeters. It is based on dynamic range compression, high speed A to D converters, a fully programmable pipeline/digital filter c...

  7. LBNL delivers front end of SNS

    CERN Document Server

    Keller, R

    2002-01-01

    After four years of construction, the linear accelerator injector that will form the front end of the US SNS has been commissioned at LBNL. Fulfilling all its major design requirements and performing reliably, the system was shipped by July.

  8. Managing Controversies in the Fuzzy Front End

    DEFF Research Database (Denmark)

    Christiansen, John K.; Gasparin, Marta

    2016-01-01

    This research investigates the controversies that emerge in the fuzzy front end (FFE) and how they are closed so the innovation process can move on. The fuzzy front has been characterized in the literature as a very critical phase, but controversies in the FFE have not been studied before....... The analysis investigates the microprocesses around the controversies that emerge during the fuzzy front end of four products. Five different types of controversies are identified: profit, production, design, brand and customers/market. Each controversy represents a threat, but also an opportunity to search...... demonstrates how the fuzzy front requires managers to deal with controversies that emerge from many different places and involve both human and non-human actors. Closing the controversies requires managers to take account of the situation, identify the problem that needs to be addressed, and initiate a search...

  9. Calculating light & lighting

    NARCIS (Netherlands)

    Nederhoff, E.M.; Marcelis, L.F.M.

    2010-01-01

    Lighting in a greenhouse is surrounded by questions. How much light to supply and when?. What intensity and light sum to aim for? Is it radiation, light growlight, PAR, photons or quanta? How much is joule, watt, lux?. What does wavelength, nanometer, spectrum, UV, IR and NIR mean?

  10. Reaction-diffusion fronts under stochastic advection

    CERN Document Server

    Martí, A C; Sancho, J M

    1997-01-01

    We study front propagation in stirred media using a simplified modelization of the turbulent flow. Computer simulations reveal the existence of the two limiting propagation modes observed in recent experiments with liquid phase isothermal reactions. These two modes respectively correspond to a wrinkled although sharp propagating interface and to a broadened one. Specific laws relative to the enhancement of the front velocity in each regime are confirmed by our simulations.

  11. Evaluating the Efficiency of Dye Removal from Textile Industry Wastewater Using the Titanium Dioxide Photocatalytic Process under UV-LED Light Irradiation: A Case Study, Hamadan Nakh Rang Factory

    Directory of Open Access Journals (Sweden)

    Asgari G

    2017-09-01

    Full Text Available Introduction: Textile industries, due to a high volume of wastewater and harmful environmental factors such as a variety of dyes, are significant industries in industrial wastewaters treatment. So, the aim of this study was to examine the efficiency of dye removal from the textile industry wastewater using the titanium dioxide photocatalytic process under UV-LED light irradiation (UV-LED/TiO2 in the treatment of the Nakh Rang factory wastewater in Hamadan City, Iran. Methods: In this experimental study, in every experiment, 100 mL sample was placed inside the LED reactor to expose to the UV light and TiO2. The effects of some parameters such as contact time, pH and dosage of TiO2 were examined, and decomposition kinetics and the synergistic effects were also determined for each process. Results: The results of the experiments showed that the UV-LED/TiO2 process can remove the dye from textile wastewater with the efficiency of 80.23% and can also remove the chemical oxygen demand (COD with the efficiency of 64.75% under the optimum conditions and during 120 minutes. Also, the reaction of dye decomposition in this wastewater was a first-order kinetic function. Conclusion: The results of this study show that the UV-LED/TiO2 can be used effectively to remove the dye and reduce the COD of the textile industry wastewater under optimal operating conditions.

  12. Constraining calving front processes on W Greenland outlet glaciers using inertial-corrected laser scanning & swath-bathymetry

    Science.gov (United States)

    Bates, R.; Hubbard, A.; Neale, M.; Woodward, J.; Box, J. E.; Nick, F.

    2010-12-01

    Calving and submarine melt account for the majority of loss from the Antarctic and over 50% of that from the Greenland Ice Sheet. These ice-ocean processes are highly efficient mass-loss mechanisms, providing a rapid link between terrestrial ice (storage) and the oceanic sink (sea level/freshwater flux) which renders the ocean-outlet-ice sheet system potentially highly non-linear. Despite this, the controls on tidewater processes are poorly understood and a process based description of them is lacking from the present generation of coupled ice sheet models. We present details from an innovative study where two survey techniques are integrated to enable the construction of accurate, ~m resolution 3d digital terrain models (DTMs) of the aerial and submarine ice front of calving outlet glaciers. A 2km range terrestrial laser scanner was combined with a 416KHz swath-interferometric system and corrected via an inertial motion unit stabilized by RTK GPS and gyro-compass data. The system was mounted aboard a heavy displacement (20,000kg) yacht in addition to a light displacement (100kg) semi-autonomous boat and used to image the aerial and submarine calving fronts of two large outlet glaciers in W Greenland. Six daily surveys, each 2.5km long were repeated across Lille Glacier during which significant ice flow, melt and calving events were observed and captured from on-ice GPS stations and time-lapse sequences. A curtain of CTD and velocity casts were also conducted to constrain the fresh and oceanic mass and energy fluxes within the fjord. The residual of successive DTMs yield the spatial pattern of frontal change enabling the processes of aerial and submarine calving and melt to be quantified and constrained in unprecedented detail. These observed frontal changes are tentatively related to local dynamic, atmospheric and oceanographic processes that drive them. A partial survey of Store Glacier (~7km calving front & W Greenland 2nd largest outlet after Jakobshavn Isbrae

  13. Relating precipitation to fronts at a sub-daily basis

    Science.gov (United States)

    Hénin, Riccardo; Ramos, Alexandre M.; Liberato, Margarida L. R.; Gouveia, Célia

    2017-04-01

    High impact events over Western Iberia include precipitation extremes that are cause for concern as they lead to flooding, landslides, extensive property damage and human casualties. These events are usually associated with low pressure systems over the North Atlantic moving eastward towards the European western coasts (Liberato and Trigo, 2014). A method to detect fronts and to associate amounts of precipitation to each front is tested, distinguishing between warm and cold fronts. The 6-hourly ERA-interim 1979-2012 reanalysis with 1°x1° horizontal resolution is used for the purpose. An objective front identification method (the Thermal Method described in Shemm et al., 2014) is applied to locate fronts all over the Northern Hemisphere considering the equivalent potential temperature as thermal parameter to use in the model. On the other hand, we settled a squared search box of tuneable dimension (from 2 to 10 degrees long) to look for a front in the neighbourhood of a grid point affected by precipitation. A sensitivity analysis is performed and the optimal dimension of the box is assessed in order to avoid over(under) estimation of precipitation. This is performed in the light of the variability and typical dynamics of warm/cold frontal systems in the Western Europe region. Afterwards, using the extreme event ranking over Iberia proposed by Ramos et al. (2014) the first ranked extreme events are selected in order to validate the method with specific case studies. Finally, climatological and trend maps of frontal activity are produced both on annual and seasonal scales. Trend maps show a decrease of frontal precipitation over north-western Europe and a slight increase over south-western Europe, mainly due to warm fronts. REFERENCES Liberato M.L.R. and R.M. Trigo (2014) Extreme precipitation events and related impacts in Western Iberia. Hydrology in a Changing World: Environmental and Human Dimensions. IAHS Red Book No 363, 171-176. ISSN: 0144-7815. Ramos A.M., R

  14. Front-of-pack nutrition labelling: testing effectiveness of different nutrition labelling formats front-of-pack in four European countries.

    Science.gov (United States)

    Feunekes, Gerda I J; Gortemaker, Ilse A; Willems, Astrid A; Lion, René; van den Kommer, Marcelle

    2008-01-01

    In two studies, the impact of eight front-of-pack nutrition labelling formats that differed in complexity was investigated across four European countries. In total 1630 men and women (18-55 yrs) were recruited from Internet panels in the United Kingdom, Germany, Italy and the Netherlands for study 1 and 776 in Italy and the United Kingdom for study 2. Participants evaluated several products (healthier and less healthy variants of the same product category) with a front-of-pack nutrition labelling format. The first study evaluated different labelling formats on consumer friendliness (comprehension, liking and credibility) and the second study measured the effect of the different labelling formats on decision-making (usage intention and process time). The results indicated minor differences in consumer friendliness and usage intention between simpler (such as Healthier Choice Tick, Smileys and Stars) and more complex front-of-pack nutrition labelling formats (such as Multiple Traffic Light, Wheel of Health and GDA scores). Endorsement by national and international health organisations strongly increased the labelling formats' credibility. Participants needed significantly less time to evaluate simpler front-of-pack labelling compared to the more complex labelling format. Thus simpler front-of-pack labelling formats seem more appropriate in a shopping environment where quick decisions are made.

  15. Pareto fronts in clinical practice for pinnacle.

    Science.gov (United States)

    Janssen, Tomas; van Kesteren, Zdenko; Franssen, Gijs; Damen, Eugène; van Vliet, Corine

    2013-03-01

    Our aim was to develop a framework to objectively perform treatment planning studies using Pareto fronts. The Pareto front represents all optimal possible tradeoffs among several conflicting criteria and is an ideal tool with which to study the possibilities of a given treatment technique. The framework should require minimal user interaction and should resemble and be applicable to daily clinical practice. To generate the Pareto fronts, we used the native scripting language of Pinnacle(3) (Philips Healthcare, Andover, MA). The framework generates thousands of plans automatically from which the Pareto front is generated. As an example, the framework is applied to compare intensity modulated radiation therapy (IMRT) with volumetric modulated arc therapy (VMAT) for prostate cancer patients. For each patient and each technique, 3000 plans are generated, resulting in a total of 60,000 plans. The comparison is based on 5-dimensional Pareto fronts. Generating 3000 plans for 10 patients in parallel requires on average 96 h for IMRT and 483 hours for VMAT. Using VMAT, compared to IMRT, the maximum dose of the boost PTV was reduced by 0.4 Gy (P=.074), the mean dose in the anal sphincter by 1.6 Gy (P=.055), the conformity index of the 95% isodose (CI(95%)) by 0.02 (P=.005), and the rectal wall V(65 Gy) by 1.1% (P=.008). We showed the feasibility of automatically generating Pareto fronts with Pinnacle(3). Pareto fronts provide a valuable tool for performing objective comparative treatment planning studies. We compared VMAT with IMRT in prostate patients and found VMAT had a dosimetric advantage over IMRT. Copyright © 2013 Elsevier Inc. All rights reserved.

  16. Improved TPB-coated light guides for liquid argon TPC light detection systems

    OpenAIRE

    Moss, Z.; Bugel, L.; Collin, G.; Conrad, J. M.; Jones, B.J.P.; Moon, J.; Toups, M; Wongjirad, T1

    2015-01-01

    Scintillation light produced in liquid argon (LAr) must be shifted from 128 nm to visible wavelengths in light detection systems used for liquid argon time-projection chambers (LArTPCs). To date, LArTPC light collection systems have employed tetraphenyl butadiene (TPB) coatings on photomultiplier tubes (PMTs) or plates placed in front of the PMTs. Recently, a new approach using TPB-coated light guides was proposed. In this paper, we report on light guides with improved attenuation lengths abo...

  17. Biomechanics of competitive front crawl swimming.

    Science.gov (United States)

    Toussaint, H M; Beek, P J

    1992-01-01

    Essential performance-determining factors in front crawl swimming can be analysed within a biomechanical framework, in reference to the physiological basis of performance. These factors include: active drag forces, effective propulsive forces, propelling efficiency and power output. The success of a swimmer is determined by the ability to generate propulsive force, while reducing the resistance to forward motion. Although for a given competitive stroke a range of optimal stroking styles may be expected across a sample of swimmers, a common element of technique related to a high performance level is the use of complex sculling motions of the hands to generate especially lift forces. By changing the orientation of the hand the propulsive force acting on the hand is aimed successfully in the direction of motion. Furthermore, the swimming velocity (v) is related to drag (A), power input (Pi, the rate of energy liberation via the aerobic/anaerobic metabolism), the gross efficiency (eg), propelling efficiency (ep), and power output (Po) according to: [formula; see text] Based on the research available at present it is concluded that: (a) drag in groups of elite swimmers homogeneous with respect to swimming technique is determined by anthropometric dimensions; (b) total mechanical power output (Po) is important since improvement in performance is related to increased Po. Furthermore, it shows dramatic changes with training and possibly reflects the size of the 'swimming engine'; (c) propelling efficiency seems to be important since it is much higher in elite swimmers (61%) than in triathletes (44%); and (d) distance per stroke gives a fairly good indication of propelling efficiency and may be used to evaluate individual progress in technical ability.

  18. Using noble gases to investigate mountain-front recharge

    Science.gov (United States)

    Manning, A.H.; Solomon, D.K.

    2003-01-01

    Mountain-front recharge is a major component of recharge to inter-mountain basin-fill aquifers. The two components of mountain-front recharge are (1) subsurface inflow from the mountain block (subsurface inflow), and (2) infiltration from perennial and ephemeral streams near the mountain front (stream seepage). The magnitude of subsurface inflow is of central importance in source protection planning for basin-fill aquifers and in some water rights disputes, yet existing estimates carry large uncertainties. Stable isotope ratios can indicate the magnitude of mountain-front recharge relative to other components, but are generally incapable of distinguishing subsurface inflow from stream seepage. Noble gases provide an effective tool for determining the relative significance of subsurface inflow, specifically. Dissolved noble gas concentrations allow for the determination of recharge temperature, which is correlated with recharge elevation. The nature of this correlation cannot be assumed, however, and must be derived for the study area. The method is applied to the Salt Lake Valley Principal Aquifer in northern Utah to demonstrate its utility. Samples from 16 springs and mine tunnels in the adjacent Wasatch Mountains indicate that recharge temperature decreases with elevation at about the same rate as the mean annual air temperature, but is on average about 2??C cooler. Samples from 27 valley production wells yield recharge elevations ranging from the valley elevation (about 1500 m) to mid-mountain elevation (about 2500 m). Only six of the wells have recharge elevations less than 1800 m. Recharge elevations consistently greater than 2000 m in the southeastern part of the basin indicate that subsurface inflow constitutes most of the total recharge in this area. ?? 2003 Published by Elsevier Science B.V.

  19. Flame front imaging in an internal-combustion engine simulator by laser-induced fluorescence of acetaldehyde.

    Science.gov (United States)

    Arnold, A; Becker, H; Suntz, R; Monkhouse, P; Wolfrum, J; Maly, R; Pfister, W

    1990-08-01

    Acetaldehyde has been used as a fluorescent dopant for two-dimensional imaging of the flame front in an internalcombustion-engine simulator. The molecule was excited with a XeCl-laser-light sheet at 308 nm, and broadband fluorescence centered at 400 nm was detected. In this way, the flame front could be marked by mapping regions of unburned gas. Also, the intake process into the engine could be followed.

  20. Analytical and numerical modeling of front propagation and interaction of fronts in nonlinear thermoviscous

    DEFF Research Database (Denmark)

    Rasmussen, Anders Rønne; Sørensen, Mads Peter; Gaididei, Yuri Borisovich

    2008-01-01

    , the model equation considered here is capable to describe waves propagating in opposite directions. Owing to the Hamiltonian structure of the proposed model equation, the front solution is in agreement with the classical Rankine Hugoniot relations. The exact front solution propagates at supersonic speed...

  1. The high dynamic range pixel array detector (HDR-PAD): Concept and design

    Energy Technology Data Exchange (ETDEWEB)

    Shanks, Katherine S.; Philipp, Hugh T.; Weiss, Joel T.; Becker, Julian; Tate, Mark W. [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Gruner, Sol M., E-mail: smg26@cornell.edu [Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, NY 14853 (United States); Cornell High Energy Synchrotron Source (CHESS), Cornell University, Ithaca, NY 14853 (United States)

    2016-07-27

    Experiments at storage ring light sources as well as at next-generation light sources increasingly require detectors capable of high dynamic range operation, combining low-noise detection of single photons with large pixel well depth. XFEL sources in particular provide pulse intensities sufficiently high that a purely photon-counting approach is impractical. The High Dynamic Range Pixel Array Detector (HDR-PAD) project aims to provide a dynamic range extending from single-photon sensitivity to 10{sup 6} photons/pixel in a single XFEL pulse while maintaining the ability to tolerate a sustained flux of 10{sup 11} ph/s/pixel at a storage ring source. Achieving these goals involves the development of fast pixel front-end electronics as well as, in the XFEL case, leveraging the delayed charge collection due to plasma effects in the sensor. A first prototype of essential electronic components of the HDR-PAD readout ASIC, exploring different options for the pixel front-end, has been fabricated. Here, the HDR-PAD concept and preliminary design will be described.

  2. Thermal diagnostics front-end electronics for LISA Pathfinder.

    Science.gov (United States)

    Sanjuán, J; Lobo, A; Nofrarias, M; Ramos-Castro, J; Riu, P J

    2007-10-01

    Precision temperature measurements are required in the LTP, the LISA technology package, for various diagnostics objectives. In this article, we describe in detail the front-end electronics design and the associated temperature sensors to achieve the LTP requirements: noise equivalent temperature of 10 microK Hz(-12) in the frequency range from 1 to 30 mHz at room temperature. We designed an ac Wheatstone bridge and a subsequent digital demodulation to minimize 1/f noise. We show experimental results where the required sensitivity in the measurement bandwidth is fulfilled.

  3. TopN-Pareto Front Search

    Energy Technology Data Exchange (ETDEWEB)

    2016-12-21

    The JMP Add-In TopN-PFS provides an automated tool for finding layered Pareto front to identify the top N solutions from an enumerated list of candidates subject to optimizing multiple criteria. The approach constructs the N layers of Pareto fronts, and then provides a suite of graphical tools to explore the alternatives based on different prioritizations of the criteria. The tool is designed to provide a set of alternatives from which the decision-maker can select the best option for their study goals.

  4. Pole solutions for flame front propagation

    CERN Document Server

    Kupervasser, Oleg

    2015-01-01

    This book deals with solving mathematically the unsteady flame propagation equations. New original mathematical methods for solving complex non-linear equations and investigating their properties are presented. Pole solutions for flame front propagation are developed. Premixed flames and filtration combustion have remarkable properties: the complex nonlinear integro-differential equations for these problems have exact analytical solutions described by the motion of poles in a complex plane. Instead of complex equations, a finite set of ordinary differential equations is applied. These solutions help to investigate analytically and numerically properties of the flame front propagation equations.

  5. RF front-end world class designs

    CERN Document Server

    Love, Janine

    2009-01-01

    All the design and development inspiration and direction a harware engineer needs in one blockbuster book! Janine Love site editor for RF Design Line,columnist, and author has selected the very best RF design material from the Newnes portfolio and has compiled it into this volume. The result is a book covering the gamut of RF front end design from antenna and filter design fundamentals to optimized layout techniques with a strong pragmatic emphasis. In addition to specific design techniques and practices, this book also discusses various approaches to solving RF front end design problems and h

  6. New insights into 3D calving investigations: use of Terrestrial LiDAR for monitoring the Perito Moreno glacier front (Southern Patagonian Ice Fields, Argentina)

    Science.gov (United States)

    Abellan, Antonio; Penna, Ivanna; Daicz, Sergio; Carrea, Dario; Derron, Marc-Henri; Guerin, Antoine; Jaboyedoff, Michel

    2015-04-01

    There exists a great incertitude concerning the processes that control and lead to glaciers' fronts disintegration, including the laws and the processes governing ice calving phenomena. The record of surface processes occurring at glacier's front has proven problematic due to the highly dynamic nature of the calving phenomenon, creating a great uncertainty concerning the processes and forms controlling and leading to the occurrence of discrete calving events. For instance, some common observational errors for quantifying the sudden occurrence of the calving phenomena include the insufficient spatial and/or temporal resolution of the conventional photogrammetric techniques and satellites missions. Furthermore, a lack of high quality four dimensional data of failures is currently affecting our ability to straightforward analyse and predict the glaciers' dynamics. In order to overcome these limitations, we used a terrestrial LiDAR sensor (Optech Ilris 3D-LR) for intensively monitoring the changes occurred at one of the most impressive calving glacier fronts: the Perito Moreno glacier, located in the Southern Patagonian Ice Fields (Argentina). Using this system, we were able to capture at an unprecedented level of detail the three-dimensional geometry of the glacier's front during five days (from 10th to 14th of March 2014). Each data collection, which was acquired at a mean interval of 20 minutes each, consisted in the automatic acquisition of several million points at a mean density between 100-200 points per square meter. The maximum attainable range for the utilized wavelength of the Ilris-LR system (1064 nm) was around 500 meters over massive ice (showing no-significant loss of information), being this distance considerably reduced on crystalline or wet ice short after the occurrence of calving events. By comparing successive three-dimensional datasets, we have investigated not only the magnitude and frequency of several ice failures at the glacier's terminus, but

  7. Monte Carlo Simulations of Luminescent Solar Concentrators with Front-Facing Photovoltaic Cells for Building Integrated Photovoltaics

    Science.gov (United States)

    Leow, Shin; Corrado, Carley; Osborn, Melissa; Carter, Sue

    2013-03-01

    Luminescent solar concentrators (LSCs) have the ability to receive light from a wide range of angles and concentrate the captured light on to small photo active areas. This enables LSCs to be integrated more extensively into buildings as windows and wall claddings on top of roof installations. LSCs with front facing PV cells collect both direct and concentrated light ensuring a gain factor greater than one. It also allows for flexibility in determining the placement and percentage coverage of PV cells when designing panels to balance reabsorption losses, power output and the level of concentration desired. A Monte-Carlo ray tracing program was developed to study the transport of photons and loss mechanisms in LSC panels and aid in design optimization. The program imports measured absorption/emission spectra and transmission coefficients as simulation parameters. Interactions of photons with the LSC panel are determined by comparing calculated probabilities with random number generators. Simulation results reveal optimal panel dimensions and PV cell layouts to achieve maximum power output.

  8. Consumer acceptability and understanding of front-of-pack nutrition labels.

    Science.gov (United States)

    Mejean, C; Macouillard, P; Péneau, S; Hercberg, S; Castetbon, K

    2013-10-01

    Front-of-pack (FOP) nutrition labelling has been proposed as a tool for helping consumers make healthy choices. Before determining its effects on consumer behaviour, factors involved in its use must be elucidated, i.e. understanding and acceptability on the part of the consumer. Among five FOP labels, we sought to determine which formats were most easily understood and accepted by a large sample of adults. Among 39 370 adults who participated in the French Nutrinet-Santé cohort study, understanding and indicators of acceptability (attitude, liking, visual attractiveness and perceived cognitive workload) were measured for five FOP labels: The currently used 'multiple traffic lights' (MTL) and 'simple traffic lights' (STL), and the 'colour range' logo (CR), the 'green tick' and the PNNS logo. We investigated the contribution of the different elements to consumer perception of FOP labels using multiple correspondence analyses. Over half of the sample population showed a high level of understanding and perceived no discomfort in terms of the different logos. Label formats were positioned along an acceptability gradient ranging from acceptance to rejection, consisting of 'liking', 'attractiveness' and indicators of perceived cognitive workload. MTL was significantly more often liked and was viewed as reliable and informative. MTL, STL and the green tick performed better than the CR and PNNS logos in terms of ease of identification and comprehension. CR was clearly the least appreciated and it had the most complex format. Consumers prefer FOP labels which give complete, reliable and simplified information on the nutrient quality of foods. © 2013 The Authors Journal of Human Nutrition and Dietetics © 2013 The British Dietetic Association Ltd.

  9. Phenomena of insulin peak fronting in size exclusion chromatography and strategies to reduce fronting.

    Science.gov (United States)

    Yu, Chi-Ming; Mun, Sungyong; Wang, Nien-Hwa Linda

    2008-05-23

    Insulin peak fronting in size exclusion chromatography (SEC) results in more than 10% yield loss in the production of insulin. The goal of this study is to understand the mechanisms of peak fronting and to develop strategies to reduce fronting and increase insulin yield. Chromatography experiments ruled out pressure surge, viscous fingering, and adsorption as the cause for peak fronting. Theoretical analysis based on a general rate model indicated that reversible dimerization is the major cause for peak fronting and reducing the dimerization equilibrium constant is the most effective method for reducing fronting. Two strategies were developed and tested to reduce the degree of dimer formation. The first strategy was to use 0.1N acetic acid as the presaturant and eluent. The second strategy was to use 0.8 or 2.8N acetic acid in 20vol.% denatured ethanol as the mobile phase. The experimental results showed that both strategies can reduce insulin peak fronting in SEC, maintain desired product purity, and increase insulin yield to higher than 98%.

  10. Apparatus and method for phase fronts based on superluminal polarization current

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, John [Los Alamos, NM; Ardavan, Houshang [Cambridge, GB; Ardavan, Arzhang [Cambridge, GB

    2012-02-28

    An apparatus and method for a radiation source involving phase fronts emanating from an accelerated, oscillating polarization current whose distribution pattern moves superluminally (that is, faster than light in vacuo). Theoretical predictions and experimental measurements using an existing prototype superluminal source show that the phase fronts from such a source can be made to be very complex. Consequently, it will be very difficult for an aircraft imaged by such a radiation to detect where this radiation has come from. Moreover, the complexity of the phase fronts makes it almost impossible for electronics on an aircraft to synthesize a rogue reflection. A simple directional antenna and timing system should, on the other hand, be sufficient for the radar operators to locate the aircraft, given knowledge of their own source's speed and modulation pattern.

  11. Image system analysis of human eye wave-front aberration on the basis of HSS

    Science.gov (United States)

    Xu, Ancheng

    2017-07-01

    Hartmann-Shack sensor (HSS) has been used in objective measurement of human eye wave-front aberration, but the research on the effects of sampling point size on the accuracy of the result has not been reported. In this paper, point spread function (PSF) of the whole system mathematical model was obtained via measuring the optical imaging system structure of human eye wave-front aberration measurement. The impact of Airy spot size on the accuracy of system was analyzed. Statistics study show that the geometry of Airy spot size of the ideal light source sent from eye retina formed on the surface of HSS is far smaller than the size of the HSS sample point image used in the experiment. Therefore, the effect of Airy spot on the precision of the system can be ignored. This study theoretically and experimentally justifies the reliability and accuracy of human eye wave-front aberration measurement based on HSS.

  12. On Multiple Questions and Multiple WH Fronting.

    Science.gov (United States)

    Rudin, Catherine

    An analysis of languages with multiple fronting of WH words (who, what, whom, etc.) looks in detail at Polish, Serbo-Croatian, Czech, Bulgarian (Slavic languages), and Romanian (a Romance language). In spite of their superficial similarity, the Slavic and East European languages that normally put all WH words at the beginning of clauses fall into…

  13. "All Quiet on the Western Front."

    Science.gov (United States)

    Soderquist, Alisa

    Based on Erich Maria Remarque's novel "All Quiet on the Western Front" and other war literature, this lesson plan presents activities designed to help students understand that works of art about war can call up strong emotions in readers; and that the writing process can be applied to writing poems. The main activity of the lesson involves…

  14. Teaching Front Handsprings from a Developmental Approach

    Science.gov (United States)

    Stork, Steve

    2006-01-01

    The front handspring is an important gymnastics skill that serves as a transition from beginner-level rolling and static balances to more advanced tumbling. It is, therefore, a skill highly desired by beginners. Early learning requires a great deal of effort during which students experience many failed attempts. Unless they are highly motivated,…

  15. Discretionary Power on the Front-line

    DEFF Research Database (Denmark)

    Sanden, Guro Refsum; Lønsmann, Dorte

    and document data, our findings show that employees face a number of different language boundaries in their everyday work, and that ad hoc and informal solutions in many cases are vital for successful cross-language communication. We introduce the concept of ‘discretionary power’ to explain how and why front...

  16. Front-end conceptual platform modeling

    DEFF Research Database (Denmark)

    Guðlaugsson, Tómas Vignir; Ravn, Poul Martin; Mortensen, Niels Henrik

    2014-01-01

    Platform thinking has been the subject of investigation and deployment in many projects in both academia and industry. Most contributions involve the restructuring of product programs, and only a few support front-end development of a new platform in parallel with technology development. This con......Platform thinking has been the subject of investigation and deployment in many projects in both academia and industry. Most contributions involve the restructuring of product programs, and only a few support front-end development of a new platform in parallel with technology development....... This contribution deals with the development of product platforms in front-end projects and introduces a modeling tool: the Conceptual Product Platform model. State of the art within platform modeling forms the base of a modeling formalism for a Conceptual Product Platform model. The modeling formalism is explored...... through an example and applied in a case in which the Conceptual Product Platform model has supported the front-end development of a platform for an electro-active polymer technology. The case describes the contents of the model and how its application supported the development work in the project...

  17. Front-end electronics for imaging detectors

    CERN Document Server

    Geronimo, G D; Radeka, V; Yu, B

    2001-01-01

    Front-end electronics for imaging detectors with large numbers of pixels (10 sup 5 -10 sup 7) is reviewed. The noise limits as a function of detector capacitance and power dissipation are presented for CMOS technology. Active matrix flat panel imagers (AMFPIs) are discussed and their potential noise performance is illustrated.

  18. Geodetic Control Points - Range Monument Master Positions in Florida

    Data.gov (United States)

    NSGIC Local Govt | GIS Inventory — This coverage indicates a inventory of Florida's Range Monuments fronting on the Atlantic Ocean, Straits of Florida, Gulf of Mexico, and the roughly seventy coastal...

  19. The science on front-of-package food labels.

    Science.gov (United States)

    Hawley, Kristy L; Roberto, Christina A; Bragg, Marie A; Liu, Peggy J; Schwartz, Marlene B; Brownell, Kelly D

    2013-03-01

    The U.S. Food and Drug Administration and Institute of Medicine are currently investigating front-of-package (FOP) food labelling systems to provide science-based guidance to the food industry. The present paper reviews the literature on FOP labelling and supermarket shelf-labelling systems published or under review by February 2011 to inform current investigations and identify areas of future research. A structured search was undertaken of research studies on consumer use, understanding of, preference for, perception of and behaviours relating to FOP/shelf labelling published between January 2004 and February 2011. Twenty-eight studies from a structured search met inclusion criteria. Reviewed studies examined consumer preferences, understanding and use of different labelling systems as well as label impact on purchasing patterns and industry product reformulation. The findings indicate that the Multiple Traffic Light system has most consistently helped consumers identify healthier products; however, additional research on different labelling systems' abilities to influence consumer behaviour is needed.

  20. The types and aspects of front-of-pack food labelling schemes preferred by adults and children.

    Science.gov (United States)

    Pettigrew, Simone; Talati, Zenobia; Miller, Caroline; Dixon, Helen; Kelly, Bridget; Ball, Kylie

    2017-02-01

    There is strong interest in front-of-pack labels (FoPLs) as a potential mechanism for improving diets, and therefore health, at the population level. The present study examined Australian consumers' preferences for different types and attributes of FoPLs to provide additional insights into optimal methods of presenting nutrition information on the front of food packets. Much research to date has focused on two main types of FoPLs - those expressing daily intake values for specific nutrients and those utilising 'traffic light' colour coding. This study extends this work by: (i) including the new Health Star Rating system recently introduced in Australia and New Zealand; (ii) allowing a large sample of consumers to self-nominate the evaluation criteria they consider to be most important in choosing between FoPLs; (iii) oversampling consumers of lower socioeconomic status; and (iv) including children, who consume and purchase food in their own right and also influence their parents' food purchase decisions. A cross-sectional online survey of 2058 Australian consumers (1558 adults and 500 children) assessed preferences between a daily intake FoPL, a traffic light FoPL, and the Health Star Rating FoPL. Across the whole sample and among all respondent subgroups (males vs females; adults vs children; lower socioeconomic status vs medium-high socioeconomic status; normal weight vs overweight/obese), the Health Star Rating was the most preferred FoPL (44%) and the daily intake guide was the least preferred (20%). The reasons most commonly provided by respondents to explain their preference related to ease of use, interpretive content, and salience. The findings suggest that a simple to use, interpretive, star-based food label represents a population-based nutrition promotion strategy that is considered helpful by a broad range of consumers. Copyright © 2016 Elsevier Ltd. All rights reserved.

  1. High-linearity CMOS RF front-end circuits

    CERN Document Server

    Ding, Yongwang

    2005-01-01

    This monograph presents techniques to improve the performance of linear integrated circuits (IC) in CMOS at high frequencies. Those circuits are primarily used in radio-frequency (RF) front-ends of wireless communication systems, such as low noise amplifiers (LNA) and mixers in a receiver and power amplifiers (PA) in a transmitter. A novel linearization technique is presented. With a small trade-off of gain and power consumption this technique can improve the linearity of the majority of circuits by tens of dB. Particularly, for modern CMOS processes, most of which has device matching better than 1%, the distortion can be compressed by up to 40 dB at the output. A prototype LNA has been fabricated in a 0.25um CMOS process, with a measured +18 dBm IIP3. This technique improves the dynamic range of a receiver RF front-end by 12 dB. A new class of power amplifier (parallel class A&B) is also presented to extend the linear operation range and save the DC power consumption. It has been shown by both simulation...

  2. Design Optimization for Superconducting Bending Magnets using Pareto Front Curve

    Science.gov (United States)

    Murata, Yukihiro; Abe, Mitsushi; Ando, Ryuya

    2017-09-01

    A novel limit design method for superconducting magnets is presented. It is particularly suitable for ion core magnets such as those used in accelerator magnets. In general, a stochastic optimization whose objective functions consist of values, e.g., the magnetic field, experience field of superconducting coils, current density, and multipole field integral, is often used. However, it is well known that the obtained solution strongly depends on the initial one. Furthermore, once the calculation model is fixed, the range of solutions is also fixed, i.e., there are times when it may be impossible to find the global optimum solution even with a lot of parameter sweeps. In this study, we draw the Pareto front curve to obtain the range and infer whether the solution is an optimum one. In addition, the Pareto front curve indicates the neighborhood solution that is substituted for the initial one. After this process a stochastic optimization is implemented with its initial design parameters. To confirm the validity, we designed a superconducting bending magnet, and it showed that this method works well.

  3. Cosmic Pressure Fronts Mapped by Chandra

    Science.gov (United States)

    2000-03-01

    A colossal cosmic "weather system" produced by the collision of two giant clusters of galaxies has been imaged by NASA's Chandra X-ray Observatory. For the first time, the pressure fronts in the system can be traced in detail, and they show a bright, but relatively cool 50 million degree Celsius central region embedded in large elongated cloud of 70 million degree Celsius gas, all of which is roiling in a faint "atmosphere"of 100 million degree Celsius gas. "We can compare this to an intergalactic cold front," said Maxim Markevitch of the Harvard-Smithsonian Center for Astrophysics, Cambridge, Mass. and leader of the international team involved in the analysis of the observations. "A major difference is that in this case, cold means 70 million degree Celsius." The gas clouds are in the core of a galaxy cluster known as Abell 2142. The cluster is six million light years across and contains hundreds of galaxies and enough gas to make a thousand more. It is one of the most massive objects in the universe. Galaxy clusters grow to vast sizes as smaller clusters are pulled inward under the influence of gravity. They collide and merge over the course of billions of years, releasing tremendous amounts of energy that heats the cluster gas to 100 million degrees Celsius. The Chandra data provides the first detailed look at the late stages of this merger process. Previously, scientists had used the German-US Roentgensatellite to produce a broad brush picture of the cluster. The elongated shape of the bright cloud suggested that two clouds were in the process of coalescing into one, but the details remained unclear. Chandra is able to measure variations of temperature, density, and pressure with unprecedented resolution. "Now we can begin to understand the physics of these mergers, which are among the most energetic events in the universe," said Markevitch. "The pressure and density maps of the cluster show a sharp boundary that can only exist in the moving environment of a

  4. Front-loaded sputum microscopy in the diagnosis of pulmonary tuberculosis.

    Science.gov (United States)

    Ndubuisi, Nwachukwu O; Azuonye, Onyeagba R; Victor, Nwaugo O; Robert, Okonkwo C; Vivian, Obiekwe

    2016-12-01

    The objectives of this study are to describe the acid-fast bacilli (AFB) yield of a front-loaded scheme in which an additional on-the-spot specimen (Xspot [Xs]) was collected 1h after the first spot specimen and to compare the default rate between the front-loaded and standard schemes. The performance of the front-loaded sputum microscopy was also compared with the standard World Health Organization (WHO) method for the diagnosis of pulmonary tuberculosis (PTB) in Anambra State, Nigeria. A total of 1487 individuals with presumptive pulmonary TB participated. Participants' age ranged from 15years and above. Three sputum specimens were submitted as spot-early morning-spot. An additional specimen (Xs) was submitted 1h after the first spot. The sputum smears were stained using the Ziehl-Neelsen technique. A total of 183 (12.3%) patients were AFB positive. The front-loaded scheme identified 182 (99%) TB patients, whereas the standard scheme identified 183 (100%) TB patients. The difference was not statistically significant (p>.05). The first two specimens of each scheme (S-Xs vs. S-M) identified 176 (96.2%) and 181 (98.9%) of PTB patients, respectively. Neither difference was statistically significant (p>.05). Default during the diagnostic process was 11% in the standard but only 0.7% in the front-load scheme. The difference was significant (pFront-loaded smear microscopy has similar performance compared with the standard scheme. More presumptive PTB cases defaulted in the standard than in the front-loaded scheme. Front-loaded smear microscopy could therefore be used in the diagnosis in PTB in Anambra State. Copyright © 2016 Asian-African Society for Mycobacteriology. Published by Elsevier Ltd. All rights reserved.

  5. Front instability and energy of the free surface

    Science.gov (United States)

    Beltrame, Philippe

    2014-05-01

    In recent years, there has been a proliferation of research devoted to the formation of preferential flow paths occurring without macroscopic heterogeneity of the porous media. DiCarlo (2013) points out the connection between "overshoot" and the front instability. Extension of the standard Richards equation is required to capture this phenomenon. In most of the improvements, interfacial phenomena as the triple line at the front are considered. For instance, velocity dependent contact angle (Wang et al., 2013) or contact angle hysteresis (Rätz and Schweizer, 2012) allow to simulate successfully the instability. Another approach proposed by Cueto-Felgueroso and Juanes (2009) introduces a macroscopic surface tension related to the existence of the water/air interface. As previously, the simulation of an advancing front displays physical looking fingering displacements. The goal of this contribution is to better understand the role of the different surface energies in the emergence of the front instability. We propose a model involving both the macroscopic surface tension and the soil wettability. This latter allows to define a contact angle and possibly hysteresis using heterogeneous wettability (Beltrame et al., 2011). Therefore, we employ the phase field approach developed by Felgueroso and Juanes, 2009 to which we add a free energy term corresponding to the wettability: a disjoining or conjoining pressure resulting from effective molecular interactions between the substrate and the free surface (DeGennes, 1985). The difference with the classical suction pressure is the hydrophobic behavior for ultra-thin film (small water saturation). Such a water repellency was recently estimated in the soil (Diamantopoulos et al. 2013). Stability analysis of an advancing front in an uniform porous media shows that macroscopic surface tension and wettability may independently produce the instability growth. In contrast, for a front stopping when reaching the layers interface of

  6. Behavioural effects of directive cues on front-of-package nutrition information: the combination matters!

    Science.gov (United States)

    Koenigstorfer, Joerg; Wąsowicz-Kiryło, Grażyna; Styśko-Kunkowska, Małgorzata; Groeppel-Klein, Andrea

    2014-09-01

    Nutrition information aims to reduce information asymmetries between manufacturers and consumers. To date, however, it remains unclear how nutrition information that is shown on the front of the packaging should be designed in order to increase both visual attention and the tendency to make healthful food choices. The present study aimed to address this gap in research. An experimental laboratory study applying mobile eye-tracking technology manipulated the presence of two directive cues, i.e. health marks and traffic light colour-coding, as part of front-of-package nutrition information on actual food packages. Participants wore mobile eye-tracking glasses during a simulated shopping trip. After the ostensible study had finished, they chose one snack (from an assortment of fifteen snacks) as a thank you for participation. All products were labelled with nutrition information according to the experimental condition. Consumers (n 160) who were mainly responsible for grocery shopping in their household participated in the study. The results showed that, in the absence of traffic light colouring, health marks reduced attention to the snack food packaging. This effect did not occur when the colouring was present. The combination of the two directive cues (v. presenting traffic light colours only) made consumers choose more healthful snacks, according to the nutrient profile. Public policy makers may recommend retailers and manufacturers implement consistent front-of-pack nutrition labelling that contains both health marks and traffic light colouring as directive cues. The combination of the cues may increase the likelihood of healthful decision making.

  7. AdS/QCD, LIight-Front Holography, and the Non-perturbative Running Coupling

    Energy Technology Data Exchange (ETDEWEB)

    Brodsky, Stanley J.; /SLAC; de Teramond, Guy; /Costa Rica U.; Deur, Alexandre; /Jefferson Lab

    2010-04-29

    The combination of Anti-de Sitter space (AdS) methods with light-front (LF) holography provides a remarkably accurate first approximation for the spectra and wavefunctions of meson and baryon light-quark bound states. The resulting bound-state Hamiltonian equation of motion in QCD leads to relativistic light-front wave equations in terms of an invariant impact variable {zeta} which measures the separation of the quark and gluonic constituents within the hadron at equal light-front time. These equations of motion in physical space-time are equivalent to the equations of motion which describe the propagation of spin-J modes in anti-de Sitter (AdS) space. The eigenvalues give the hadronic spectrum, and the eigenmodes represent the probability distributions of the hadronic constituents at a given scale. A positive-sign confining dilaton background modifying AdS space gives a very good account of meson and baryon spectroscopy and form factors. The light-front holographic mapping of this model also leads to a non-perturbative effective coupling {alpha}{sub s}{sup Ads} (Q{sup 2}) which agrees with the effective charge defined by the Bjorken sum rule and lattice simulations. It displays a transition from perturbative to nonperturbative conformal regimes at a momentum scale {approx} 1 GeV. The resulting {beta}-function appears to capture the essential characteristics of the full {beta}-function of QCD, thus giving further support to the application of the gauge/gravity duality to the confining dynamics of strongly coupled QCD.

  8. Vertical profiles of pelagic communities in the vicinity of the Azores Front and their implications to deep ocean ecology

    Science.gov (United States)

    Angel, M. V.

    remaining quite high to depths of 800m during the summer. At night, the ratios tended to be lower as a result of diel vertical migration, but except in one or two of the deepest samples the planktonic biomass always exceeded that of the micronekton. The total biomass profiles were very similar in shape between the stations, although there were quite large differences in the depths of the quartiles. There were substantial differences between the day and the night profiles. These could be attributed mostly to the effects of diel vertical migrations, but must also have included unquantifiable effects as a result of variations in net avoidance. The subdivision of the catches into the major taxonomic groups showed that the degree of avoidance varied substantially between them; euphausiids were the most effective daytime avoiders, but decapod crustaceans and fish showed a suprisingly small tendency to avoid. The ranges and the numbers of each group undertaking vertical migrations varied markedly between the stations, and these differences were expressed in the biomass estimates. Attempts have been made to quantify the movement of biomass in and out of the surface 200m and 500m resulting from these migrations. There were substantial changes in migratory behaviour across the front, even though there were no detectable changes in the light profiles. The data also imply that the micronektonic migrants play an important role in the active transport of organic substances down from the euphotic zone to mesopelagic depths (>500m), either in their gut contents or directly as a result of predation at depth. In addition, migrating plankton seem likely to be important in redistributing nutrients about the nutricline in these oligotrophic regions where the water column stability limits physical vertical mixing processes. Preliminary estimates suggest that their influence may be sufficiently large to alter the ratio between “new” and “old” production.

  9. Supersymmetry across the light and heavy-light hadronic spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Dosch, Hans Gunter [Institut fur Theoretische Physik, Heidelberg (Germany); de Teramond, Guy F. [Univ. de Costa Rica, San Pedro de Montes de Oca (Costa Rica); Brodsky, Stanley J. [SLAC National Accelerator Lab., Menlo Park, CA (United States)

    2015-10-07

    Relativistic light-front bound-state equations for mesons and baryons can be constructed in the chiral limit from the supercharges of a superconformal algebra which connect baryon and meson spectra. Quark masses break the conformal invariance, but the basic underlying supersymmetric mechanism, which transforms meson and baryon wave functions into each other, still holds and gives remarkable connections across the entire spectrum of light and heavy-light hadrons. As a result, we also briefly examine the consequences of extending the supersymmetric relations to double-heavy mesons and baryons.

  10. Fine-scale recognition and use of mesoscale fronts by foraging Cape gannets in the Benguela upwelling region

    Science.gov (United States)

    Sabarros, Philippe S.; Grémillet, David; Demarcq, Hervé; Moseley, Christina; Pichegru, Lorien; Mullers, Ralf H. E.; Stenseth, Nils C.; Machu, Eric

    2014-09-01

    Oceanic structures such as mesoscale fronts may become hotspots of biological activity through concentration and enrichment processes. These fronts generally attract fish and may therefore be targeted by marine top-predators. In the southern Benguela upwelling system, such fronts might be used as environmental cues by foraging seabirds. In this study we analyzed high-frequency foraging tracks (GPS, 1 s sampling) of Cape gannets Morus capensis from two colonies located on the west and east coast of South Africa in relation to mesoscale fronts detected on daily high-resolution chlorophyll-a maps (MODIS, 1 km). We tested the association of (i) searching behavior and (ii) diving activity of foraging birds with mesoscale fronts. We found that Cape gannets shift from transiting to area-restricted search mode (ARS) at a distance from fronts ranging between 2 and 11 km (median is 6.7 km). This suggests that Cape gannets may be able to sense fronts (smell or vision) or other predators, and that such detection triggers an intensified investigation of their surroundings (i.e. ARS). Also we found that diving probability increases near fronts in 11 out of 20 tracks investigated (55%), suggesting that Cape gannets substantially use fronts for feeding; in the remaining cases (45%), birds may have used other cues for feeding including fishing vessels, particularly for gannets breeding on the west coast. We demonstrated in this study that oceanographic structures such as mesoscale fronts are important environmental cues used by a foraging seabird within the rich waters of an upwelling system. There is now need for further investigations on how Cape gannets actually detect these fronts.

  11. Assessment of a Low-Power 65 nm CMOS Technology for Analog Front-End Design

    Science.gov (United States)

    Manghisoni, Massimo; Gaioni, Luigi; Ratti, Lodovico; Re, Valerio; Traversi, Gianluca

    2014-02-01

    This work is concerned with the study of the analog properties of MOSFET devices belonging to a 65 nm CMOS technology with emphasis on intrinsic voltage gain and noise performance. This node appears to be a robust and promising solution to cope with the unprecedented requirements set by silicon vertex trackers in experiments upgrades and future colliders as well as by imaging detectors at light sources and free electron lasers. In this scaled-down technology, the impact of new dielectric materials and processing techniques on the analog behavior of MOSFETs has to be carefully evaluated. An inversion level design methodology has been adopted to analyze data obtained from device measurements and provide a powerful tool to establish design criteria for detector front-ends in this nanoscale CMOS process. A comparison with data coming from less scaled technologies, such as 90 nm and 130 nm nodes, is also provided and can be used to evaluate the resolution limits achievable for low-noise charge sensitive amplifiers in the 100 nm minimum feature size range.

  12. Photodetectors and front-end electronics for the LHCb RICH upgrade

    CERN Document Server

    INSPIRE-00399968

    2016-01-01

    The RICH detectors of the LHCb experiment provide identification of hadrons produced in high energy proton-proton collisions in the LHC at CERN over a wide momentum range (2 to 100 GeV/c). Cherenkov light is collected on photon detector planes sensitive to single photons. The RICH will be upgraded (in 2019) to read out every bunch crossing, at a rate of 40 MHz. The current hybrid photon detectors (HPD) will be replaced with multi-anode photomultiplier tubes (customisations of the Hamamatsu R11265 and the H12699 MaPMTs). These 8$\\times$8 pixel devices meet the experimental requirements thanks to their small pixel size, high gain, negligible dark count rate ($\\sim$50 Hz/cm$^2$) and moderate cross-talk. The measured performance of several tubes is reported, together with their long-term stability. A new 8-channel front-end chip, named CLARO, has been designed in 0.35 $\\mu$m CMOS AMS technology for the MaPMT readout. The CLARO chip operates in binary mode and combines low power consumption (\\hbox{$\\sim$1 mW/Ch}),...

  13. Real-time diameter measurement using diffuse light

    Science.gov (United States)

    Luo, Xiaohe; Hui, Mei; Zhu, Qiudong; Wang, Shanshan

    2016-09-01

    A method for on-line rapid determination of the diameter of metallic cylinder is introduced in this paper. Under the radiation of diffuse light, there is a bright area close to the margin of metallic cylinder, and the method of this paper is based on the intensity distribution of the bright area. In this paper, with the radiation by a diffuse plane light with special shape, we present the relation expression of the distance between the peak point and the real edge of the cylinder and the distance between the diffuse light and the pinhole aperture of the camera. With the expression, the diameter of the cylinder to be measured can be calculated. In the experiments, monochromatic LED uniting with ground glass forms the diffuse light source, then the light irradiates the tested cylinder. After the cylinder, we use a lens with a front pinhole stop to choose the light into CMOS, then a computer is used to analyze images and export the measurement results. The measuring system using this method is very easily implemented, so it can realize the on-line rapid measurement. Experimental results are presented for six metallic cylinders with the diameter in 5 18mm range and roughness in Ra- 0.02um, and the precision reaches 3um.

  14. Mineral replacement front propagation in deformed rocks

    Science.gov (United States)

    Beaudoin, Nicolas; Koehn, Daniel; Kelka, Ulrich

    2015-04-01

    Fluid migrations are a major agent of contaminant transport leading to mineral replacement in rocks, impacting their properties as porosity, permeability, and rheology. Understanding the physical and chemical mechanisms that govern mineralogical replacement during and after deformation is required to better understand complex interplays between fluid and rocks that are involved in faulting, seismic cycle, and resource distribution in the upper crust. Dolomitization process related to hydrothermal fluid flow is one of the most studied and debated replacement processes in earth sciences. Dolomitization of limestone is of economic importance as well, as it stands as unconventional oil reservoirs and is systematically observed in Mississippian-Valley Type ore deposit. Despite recent breakthrough about dolomitization processes at large-scale, the small-scale propagation of the reaction front remains unclear. It is poorly documented in the occurrence of stylolites and fractures in the medium while pressure-solution and fracture network development are the most efficient deformation accomodation mechanism in limestone from early compaction to layer-parallel shortening. Thus, the impact of such network on geometry of replaced bodies and on replacement front propagation deserves specific attention. This contribution illustrates the role of fracture and stylolites on the propagation of a reaction front. In a 2 dimensional numerical model we simulate the dolomitization front propagation in a heterogeneous porous medium. The propagation of the reaction front is governed by the competition between advection and diffusion processes, and takes into account reaction rates, disorder in the location of the potential replacement seeds, and permeability heterogeneities. We add stylolites and fractures that can act as barriers or drains to fluid flow according to their orientation and mineralogical content, which can or cannot react with the contaminant. The patterns produced from

  15. Lamps and lighting

    CERN Document Server

    Cayless, MA; Marsden, A M

    2012-01-01

    This book is a comprehensive guide to the theory and practice of lighting. Covering the physics of light production, light sources, circuits and a wide variety of lighting applications, it is both suitable as a detailed textbook and as thoroughly practical guide for practising lighting engineers. This fourth edition of Lamps and Lighting has been completely updated with new chapters on the latest lamp technology and applications. The editors ahve called upon a wide range of expertise and as a result many sections have been broadened to include both European and US practice.The book begins with

  16. Clinical-microbiological research of action ozone therapy and light-emetting diode radiation of red range (630 nanometers) on microflora of the hole extracted toothatalveolitis and limited osteomyelitis of jaws.

    Science.gov (United States)

    Chergeshtov, U I; Tsarev, V N; Volkov, A G; Nosik, A S; Dikopova, N J; Malanchuk, D A

    2016-01-01

    As a result of cliniko-microbiological research the data testifying to substantial improvement of efficiency of antimicrobictherape at inclusion in a complex of medical actions at alveolitis and the limited osteomyelitis of a jow ozone therapy in a combination with a light-emettinf diode irradiation of the hole extracted teeth red ( 630 nanometers) are obtained by light.

  17. Helical crack-front instability in mixed-mode fracture.

    Science.gov (United States)

    Pons, Antonio J; Karma, Alain

    2010-03-04

    Planar crack propagation under pure tension loading (mode I) is generally stable. However, it becomes universally unstable with the superposition of a shear stress parallel to the crack front (mode III). Under this mixed-mode (I + III) loading configuration, an initially flat parent crack segments into an array of daughter cracks that rotate towards a direction of maximum tensile stress. This segmentation produces stepped fracture surfaces with characteristic 'lance-shaped' markings observed in a wide range of engineering and geological materials. The origin of this instability remains poorly understood and a theory with which to predict the surface roughness scale is lacking. Here we perform large-scale simulations of mixed-mode I + III brittle fracture using a continuum phase-field method that describes the complete three-dimensional crack-front evolution. The simulations reveal that planar crack propagation is linearly unstable against helical deformations of the crack front, which evolve nonlinearly into a segmented array of finger-shaped daughter cracks. Furthermore, during their evolution, facets gradually coarsen owing to the growth competition of daughter cracks in striking analogy with the coarsening of finger patterns observed in nonequilibrium growth phenomena. We show that the dynamically preferred unstable wavelength is governed by the balance of the destabilizing effect of far-field stresses and the stabilizing effect of cohesive forces on the process zone scale, and we derive a theoretical estimate for this scale using a new propagation law for curved cracks in three dimensions. The rotation angles of coarsened facets are also compared to theoretical predictions and available experimental data.

  18. Multiclass gene selection using Pareto-fronts.

    Science.gov (United States)

    Rajapakse, Jagath C; Mundra, Piyushkumar A

    2013-01-01

    Filter methods are often used for selection of genes in multiclass sample classification by using microarray data. Such techniques usually tend to bias toward a few classes that are easily distinguishable from other classes due to imbalances of strong features and sample sizes of different classes. It could therefore lead to selection of redundant genes while missing the relevant genes, leading to poor classification of tissue samples. In this manuscript, we propose to decompose multiclass ranking statistics into class-specific statistics and then use Pareto-front analysis for selection of genes. This alleviates the bias induced by class intrinsic characteristics of dominating classes. The use of Pareto-front analysis is demonstrated on two filter criteria commonly used for gene selection: F-score and KW-score. A significant improvement in classification performance and reduction in redundancy among top-ranked genes were achieved in experiments with both synthetic and real-benchmark data sets.

  19. Front contact solar cell with formed emitter

    Science.gov (United States)

    Cousins, Peter John [Menlo Park, CA

    2012-07-17

    A bipolar solar cell includes a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell. An antireflection layer may be formed on a textured front surface of the silicon substrate. A negative polarity metal contact on the front side of the solar cell makes an electrical connection to the substrate, while a positive polarity metal contact on the backside of the solar cell makes an electrical connection to the polysilicon emitter. An external electrical circuit may be connected to the negative and positive metal contacts to be powered by the solar cell. The positive polarity metal contact may form an infrared reflecting layer with an underlying dielectric layer for increased solar radiation collection.

  20. Frontón en Aroztegia

    OpenAIRE

    Arraztoa Brust, Xabier

    2011-01-01

    El objetivo de este proyecto fin de carrera es el diseño global de un frontón cubierto con sus correspondientes gradas e instalaciones en el barrio Aroztegia de la localidad de Lekaroz, en el Valle de Baztán. Asimismo y respecto al cálculo estructural, se ha diseñado y calculado una estructura metálica, la cubierta y su cimentación de hormigón armado correspondiente. Cabe destacar que las características y medidas del frontón lo hacen apto para la alta competición de pelota a mano, paleta con...

  1. Laser modes with helical wave fronts

    Science.gov (United States)

    Harris, M.; Hill, C. A.; Tapster, P. R.; Vaughan, J. M.

    1994-04-01

    We report the operation of an argon-ion laser in pure (single-frequency) ``doughnut'' modes of order m=1, 2, and 3. The phase discontinuity at the center of these modes leads to striking two-beam interference patterns that clearly demonstrate the existence of a helical cophasal surface (wave front). The doughnut mode with m=1 (usually called TEM*01) displays a forking interference fringe pattern characteristic of a pure single helix. The m=2 mode shows a pattern with four extra prongs, establishing that the cophasal surface is a two-start or double helix; the m=3 mode is a triple helix with a six-extra-pronged pattern. Each pure doughnut mode is shown to have two possible states corresponding to output wave fronts of opposite helicity.

  2. Dispersion management of the SULF front end

    Science.gov (United States)

    Li, Shuai; Wang, Cheng; Liu, Yanqi; Xu, Yi; Liu, Zhengzheng; Lu, Jun; Li, Yanyan; Liu, Xingyan; Li, Zhaoyang; Leng, Yuxin; Li, Ruxin

    2017-04-01

    To manage dispersion of the front end in the Shanghai Superintense Ultrafast Laser Facility (SULF), which is a large-scale project aimed at delivering 10 PW laser pulses, a stretcher based on a combination of a grating and a prism (grism) pair is inserted between an Öffner-triplet-type stretcher and a regenerative amplifier to reduce high-order dispersion introduced by optical materials at the amplification stage. The alignment of the grism pair is implemented by controlling the far-field pattern of the output beam of the grism pair. The energy of the front end reaches up to 7 J at a 1-Hz repetition rate. Experimental results show that the pulse duration can be compressed to 22.4 fs and the spectral distortion over the spectrum is less than 2.25 rad.

  3. Lawfare: The Legal Front of the IDF

    OpenAIRE

    Avihai Mandelblit

    2012-01-01

    Lawfare is closely linked to the theme of this issue of Military and Strategic Affairs: the challenges facing the regular armies of law-abiding nations engaged in asymmetrical confrontations in densely populated civilian urban areas. Therefore, as part of its preparations for the challenges it may have to face in the future, particularly in this type of fighting, the IDF must give the proper weight to the legal front that is likely to develop as an integral part of the same confrontation.

  4. Front roughening of flames in discrete media

    Science.gov (United States)

    Lam, Fredric; Mi, XiaoCheng; Higgins, Andrew J.

    2017-07-01

    The morphology of flame fronts propagating in reactive systems composed of randomly positioned, pointlike sources is studied. The solution of the temperature field and the initiation of new sources is implemented using the superposition of the Green's function for the diffusion equation, eliminating the need to use finite-difference approximations. The heat released from triggered sources diffuses outward from each source, activating new sources and enabling a mechanism of flame propagation. Systems of 40 000 sources in a 200 ×200 two-dimensional domain were tracked using computer simulations, and statistical ensembles of 120 realizations of each system were averaged to determine the statistical properties of the flame fronts. The reactive system of sources is parameterized by two nondimensional values: the heat release time (normalized by interparticle diffusion time) and the ignition temperature (normalized by adiabatic flame temperature). These two parameters were systematically varied for different simulations to investigate their influence on front propagation. For sufficiently fast heat release and low ignition temperature, the front roughness [defined as the root mean square deviation of the ignition temperature contour from the average flame position] grew following a power-law dependence that was in excellent agreement with the Kardar-Parisi-Zhang (KPZ) universality class (β =1 /3 ). As the reaction time was increased, lower values of the roughening exponent were observed, and at a sufficiently great value of reaction time, reversion to a steady, constant-width thermal flame was observed that matched the solution from classical combustion theory. Deviation away from KPZ scaling was also observed as the ignition temperature was increased. The features of this system that permit it to exhibit both KPZ and non-KPZ scaling are discussed.

  5. Developing leadership skills at the front line.

    Science.gov (United States)

    Jeavons, Richard

    2011-10-01

    The health secretary announced in July plans to launch a NHS Leadership Academy. This article explains what progress has been made in setting up the body and enabling it to support nurses and other front line staff to develop the leadership skills needed to transform the NHS into a genuinely patient-centred service, one in which different services work together to provide integrated care.

  6. Chemical air mass differences near fronts

    OpenAIRE

    Bethan, S.; Vaughan, G.; Gerbig, C.; Volz-Thomas, A.; Richer, H; Tiddeman, D.

    1998-01-01

    Two case studies are presented of aircraft measurements (ozone, NOy, CO, and meteorological parameters) in the Vicinity of fronts located over the eastern side of the North Atlantic Ocean during spring 1994. The aim of these studies was twofold: (1) to investigate whether frontal circulations can transport ozone from the boundary layer to the free troposphere in well-defined layer; and (2) to ascertain whether or not conveyor belts associated with extratropical cyclones exhibit well-defined c...

  7. Trunk muscle activity during front crawl swimming

    OpenAIRE

    Martens, Jonas; Pellegrims, Ward; Einarsson, Ingi Thor; Fernandes, Ricardo; Staes, Filip; Daly, Daniel

    2013-01-01

    Introduction Core stability training is of increasing interest to both researchers and coaches. Sufficient core stability is needed to balance forces generated by the upper and lower extremities separately (Hibbs et al., 2008). In swimming the development of wireless EMG has created new possibilities to study underwater muscle activity with little hinder. The purpose here was to analyze lower trunk muscle activation during front crawl swimming and examine how trunk muscle activity is relat...

  8. Combustion Waves and Fronts in Flows

    Science.gov (United States)

    Clavin, Paul; Searby, Geoff

    2016-07-01

    Preface; Introduction; Part I. Physical Insights: 1. General considerations; 2. Laminar premixed flames; 3. Turbulent premixed flames; 4. Gaseous shocks and detonations; 5. Chemical kinetics of combustion; 6. Laser-driven ablation front in ICF; 7. Explosion of massive stars; Part II. Detailed Analytical Studies: 8. Planar flames; 9. Flame kernels and flame balls; 10. Wrinkled flames; 11. Ablative Rayleigh-Taylor instability; 12. Shock waves and detonations; Part III. Complements: 13. Statistical physics; 14. Chemistry; 15. Flows; References; Index.

  9. Prototype ALICE front-end card

    CERN Multimedia

    Maximilien Brice

    2004-01-01

    This circuit board is a prototype 48-channel front end digitizer card for the ALICE time projection chamber (TPC), which takes electrical signals from the wire sensors in the TPC and shapes the data before converting the analogue signal to digital data. A total of 4356 cards will be required to process the data from the ALICE TPC, the largest of this type of detector in the world.

  10. On the Front Lines of Rare Disease Research

    Science.gov (United States)

    ... turn JavaScript on. Feature: Rare Diseases On the Front Lines of Rare Disease Research Past Issues / Spring ... Diagnosis" Making the Invisible Patients Visible / On the Front Lines of Rare Disease Research Spring 2016 Issue: ...

  11. Consumer testing of the acceptability and effectiveness of front-of-pack food labelling systems for the Australian grocery market.

    Science.gov (United States)

    Kelly, Bridget; Hughes, Clare; Chapman, Kathy; Louie, Jimmy Chun-Yu; Dixon, Helen; Crawford, Jennifer; King, Lesley; Daube, Mike; Slevin, Terry

    2009-06-01

    The placement of nutrition information on the front of food packages has been proposed as a method of providing simplified and visible nutrition information. This study aimed to determine the most acceptable and effective front-of-pack food labelling system for Australian consumers. Consumers' preferences and ability to compare the healthiness of mock food products were assessed for different front-of-pack labelling systems. Four systems were tested, including two variations of the Percentage Daily Intake system (Monochrome %DI and Colour-Coded %DI), which displays the proportion of daily nutrient contribution that a serve of food provides; and two variations of the Traffic Light (TL) system (Traffic Light and Traffic Light + Overall Rating), which uses colour-coding to indicate nutrient levels. Intercept surveys with 790 consumers were conducted, where each participant was exposed to a single labelling system for performance testing. Participants indicated strong support for the inclusion of nutrient information on total fat, saturated fat, sugar and sodium on the front of packages, and a consistent labelling format across all products. Using the TL system, participants were five times more likely to identify healthier foods compared with the Monochrome %DI system [odds ratio (OR) = 5.18; p front-of-pack food labelling. The TL system was the most effective in assisting consumers to identify healthier foods. Mandatory TL labelling regulations are recommended to assist consumers in making healthy food choices.

  12. Silicon Photomultipliers and front-end electronics performance for Cherenkov Telescope Array camera development

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosi, G. [INFN – Sezione di Perugia, Perugia (Italy); Bissaldi, E.; Giglietto, N.; Giordano, F. [Dipartimento Interateneo di Fisica, Università e Politecnico di Bari, Bari (Italy); INFN – Sezione di Bari, Bari (Italy); Ionica, M. [INFN – Sezione di Perugia, Perugia (Italy); Paoletti, R. [Università di Siena, Siena (Italy); INFN – Sezione di Pisa, Pisa (Italy); Rando, R. [Università di Padova, Padova (Italy); INFN – Sezione di Padova, Padova (Italy); Simone, D., E-mail: daniela.simone@ba.infn.it [INFN – Sezione di Bari, Bari (Italy); Vagelli, V. [INFN – Sezione di Perugia, Perugia (Italy)

    2017-02-11

    In the last few years a number of efforts have been undertaken to develop new technology related to Silicon Photomultipliers (SiPMs). These photosensors consist of an array of identical Avalanche Photodiodes operating in Geiger mode and connected in parallel to a single output. The Italian Institute of Nuclear Physics (INFN) is involved in the R&D program Progetto Premiale Telescopi CHErenkov made in Italy (TECHE.it) to develop photosensors for a SiPM based camera that will be part of the Cherenkov Telescope Array (CTA) observatory. In this framework tests are ongoing on innovative devices suitable to detect Cherenkov light in the blue and near-UV wavelength region, the so-called Near Ultra-Violet Silicon Photomultipliers (NUV SiPMs). The tests on photosensors produced by Fondazione Bruno Kessler (FBK) are revealing promising performance: low operating voltage, capability to detect very low intensity light down to a single photon and high Photo Detection Efficiency (PDE) in the range 390–410 nm. In particular the developed device is a High Density NUV-SiPM (NUV-HD SiPM) based on a micro-cell of 30 μm×30 μm and 6 mm×6 mm area. Tests on this detector in single-cell configuration and in a matrix arrangement have been done. At the same time front-end electronics based on the waveform sampling technique optimized for the new NUV-HD SIPMs is under study and development.

  13. Association of perception of front-of-pack labels with dietary, lifestyle and health characteristics.

    Science.gov (United States)

    Méjean, Caroline; Macouillard, Pauline; Péneau, Sandrine; Lassale, Camille; Hercberg, Serge; Castetbon, Katia

    2014-01-01

    To identify patterns of perception of front-of-pack (FOP) nutrition labels and determine dietary, lifestyle and health profiles related to such patterns. Cross-sectional. 28,952 French adults participating in the web-based Nutrinet-Santé cohort. Perception was measured using indicators of understanding and acceptability for three simple FOP labels ("green tick", the logo of the French Nutrition and Health Program and "simple traffic lights" (STL)), and two detailed FOP formats ("multiple traffic lights" (MTL) and "color range" logo (CR)), placed on ready-to-eat soup packages. Dietary intake data were collected using three web-based 24 h records. Associations of perception patterns with individual characteristics, including diet, lifestyle and health status, were examined using analysis of covariance and logistic regression, adjusted for socio-demographic and economic factors. No clear trend emerged concerning differences in dietary intake between perception groups. Low physical activity and obesity were more frequent in the 'favorable to STL' group (respectively, 20.7% and 10.7%). The 'favorable to MTL' group included the highest percentage of individuals who declared type 2 diabetes (2.2%). Persons with hypertension were proportionally more numerous in the 'favorable to MTL' and the 'favorable to CR logo' groups (respectively, 9.5% and 9.3%). After adjustment for socio-demographic and economic factors, no FOP label stood out as being more suitable than another for reaching populations with poor diet. However, both STL and MTL may be most appropriate for increasing awareness of healthy eating among groups at higher risk of nutrition-related chronic diseases.

  14. Association of perception of front-of-pack labels with dietary, lifestyle and health characteristics.

    Directory of Open Access Journals (Sweden)

    Caroline Méjean

    Full Text Available OBJECTIVE: To identify patterns of perception of front-of-pack (FOP nutrition labels and determine dietary, lifestyle and health profiles related to such patterns. DESIGN: Cross-sectional. PARTICIPANTS/SETTING: 28,952 French adults participating in the web-based Nutrinet-Santé cohort. OUTCOME MEASURES: Perception was measured using indicators of understanding and acceptability for three simple FOP labels ("green tick", the logo of the French Nutrition and Health Program and "simple traffic lights" (STL, and two detailed FOP formats ("multiple traffic lights" (MTL and "color range" logo (CR, placed on ready-to-eat soup packages. Dietary intake data were collected using three web-based 24 h records. STATISTICAL ANALYSES: Associations of perception patterns with individual characteristics, including diet, lifestyle and health status, were examined using analysis of covariance and logistic regression, adjusted for socio-demographic and economic factors. RESULTS: No clear trend emerged concerning differences in dietary intake between perception groups. Low physical activity and obesity were more frequent in the 'favorable to STL' group (respectively, 20.7% and 10.7%. The 'favorable to MTL' group included the highest percentage of individuals who declared type 2 diabetes (2.2%. Persons with hypertension were proportionally more numerous in the 'favorable to MTL' and the 'favorable to CR logo' groups (respectively, 9.5% and 9.3%. CONCLUSIONS: After adjustment for socio-demographic and economic factors, no FOP label stood out as being more suitable than another for reaching populations with poor diet. However, both STL and MTL may be most appropriate for increasing awareness of healthy eating among groups at higher risk of nutrition-related chronic diseases.

  15. Front-to-rear crashes involving two vehicles with severe driver injury.

    Science.gov (United States)

    Viano, David C; Parenteau, Chantal S

    2012-01-01

    This study investigates the risk for severe-to-fatal injury (Maximum Abbreviated Injury Scale [MAIS] 4+F) to drivers in two-vehicle crashes involving front impacts into the rear of another vehicle. 1995-2009 National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) was analyzed for driver injuries in front-to-rear crashes without rear occupants in either vehicle. The study involved 13+-year-old front outboard occupants in model year (MY) 1995+ light vehicles. Injury severity was subdivided into MAIS 0+6 and MAIS 4+F to assess the risk of severe-to-fatal injury (MAIS 4+F/MAIS 0+6). Injury risks were determined using weighted data for the drivers by impact type. Standard errors were calculated in SAS to determine ±95 percent confidence intervals. An in-depth analysis was made of individual cases with severely injured drivers in the front and rear impacts. There were 215,163 drivers in the 15 years of NASS-CDS with known injuries in front-to-rear two-vehicle collisions; 624 were severely injured (MAIS 4+F) in the rear impacts and 124 in the front impacts. The risk for severe-to-fatal driver injury was 0.290 ± 0.241 percent in rear impacts and 0.058 ± 0.057 percent in front impacts. The difference was not statistically significant (P > .05). There were 13 unweighted cases with MAIS 4+F driver injury in rear impacts. Most (77%) involved intrusion in the vicinity of the driver's seating area with the seat supported upright or deformed forward. There were 5 unweighted cases with severely injured drivers in frontal impacts. Three (60%) involved intrusion due to offset frontal loading. There was only one crash where both drivers were severely injured. In front-to-rear crashes with two vehicles, typically one driver was severely injured, not both. The risk of severe injury was not significantly different for drivers in the front or rear impacts. The risk was higher in rear impacts due to intrusion into the driver's seating area that supported or pushed

  16. Topology optimization of front metallization patterns for solar cells

    NARCIS (Netherlands)

    Gupta, D.K.; Langelaar, M.; Barink, M.; Keulen, F. van

    2015-01-01

    This paper presents the application of topology optimization (TO) for designing the front electrode patterns for solar cells. Improving the front electrode design is one of the approaches to improve the performance of the solar cells. It serves to produce the voltage distribution for the front

  17. Kinematic analysis of three water polo front crawl styles.

    Science.gov (United States)

    De Jesus, Karla; Figueiredo, Pedro; De Jesus, Kelly; Pereira, Filipa; Vilas-Boas, J Paulo; Machado, Leandro; Fernandes, Ricardo J

    2012-01-01

    During water polo matches, players use different front crawl styles. The purpose of this study was to conduct a kinematic analysis of three water polo front crawl styles: front crawl with head under water, front crawl with head above water, and front crawl when leading the ball. Ten proficient water polo players performed 3 × 15 m sprints in each front crawl style, which were recorded three-dimensionally by two surface and four underwater cameras. The results showed no differences in performance and several kinematic characteristics among the water polo front crawl styles. However, front crawl when leading the ball showed shorter stroke length and greater stroke frequency. Front crawl with head underwater presented greater maximal finger depth and elbow angle at mid-stroke position. Front crawl with head above water and when leading the ball showed greater trunk obliquity and maximal depth of right and left foot, and shorter kick stroke frequency. The findings suggest that proficient players learn to master front crawl with head above water to achieve top velocity. Despite the common use of the front crawl with head underwater as the basis for water polo fast displacement, coaches should emphasize the use of the specific water polo styles to attain high performance.

  18. 49 CFR 393.44 - Front brake lines, protection.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 5 2010-10-01 2010-10-01 false Front brake lines, protection. 393.44 Section 393... ACCESSORIES NECESSARY FOR SAFE OPERATION Brakes § 393.44 Front brake lines, protection. On every bus, if... any of the front wheels is broken, the driver can apply the brakes on the rear wheels despite such...

  19. 16 CFR 1512.13 - Requirements for front fork.

    Science.gov (United States)

    2010-01-01

    ... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Requirements for front fork. 1512.13 Section 1512.13 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Regulations § 1512.13 Requirements for front fork. The front fork shall...

  20. Evolved hypabyssal rocks from Station 7, Apennine Front, Apollo 15

    Science.gov (United States)

    Ryder, G.; Martinez, R. R.

    1991-01-01

    Three 4-10-mm coarse fines cataclasized particles from Station 7 on the Apennine Front, Apollo 15, have mineral phases and compositions similar to those in the quartz monzodiorites in 15405, from Station 6a. The chemical analyses of the Station 7 particles have lower trace-element abundances and flatter rare earth element patterns, and there is considerable disagreement among and between mineral norms and modes. The zoning of pyroxenes and the nature of their exsolution strongly suggest a common origin of the three particles and 15405 quartz monzodiorites in a hypabyssal environment. The differences then are a result of short-range differences in igneous modes considerably exaggereted by unrepresentative sampling of coarse rocks in small fragments. The parent hypabyssal rocks crystallized (4.35 Ga ago?) by fractionation of a poorly defined KREEP basalt magma, before the residual liquid reached any field of immiscibility. An impact event, possibly that forming Aristillus, ejected the upper levels of the bypabyssal intrusion, some of the ejecta spraying the Apennine Front.

  1. Age-dependent mortality, fecundity and mobility effects on front speeds: theory and application to the Neolithic transition

    Science.gov (United States)

    Pérez-Losada, Joaquim; Fort, Joaquim

    2010-11-01

    We present a model that makes it possible to analyze the effect of the age dependences of mortality, fertility and dispersal persistence on the speed of propagating fronts in two spatial dimensions. Speeds derived analytically agree very well with those obtained from numerical simulations. Infant mortality and total fecundity are the most relevant parameters affecting the front speed, whereas the adult mortality rates and dispersal persistences are less important. We apply the model to the Neolithic transition in Europe. The predictions of the model are consistent with the archaeological data for the front speed, provided that the infant mortality lies within a relatively narrow range.

  2. Vehicle lighting within built-up areas : shortened version contribution to OECD- initiated Group on "Lighting, Visibility and Accidents".

    NARCIS (Netherlands)

    Schreuder, D.A.

    1976-01-01

    One of the questions confronting both the appropriate authorities and scientific researchers concerns the most suitable lighting for vehicles on roads with (fixed) lighting systems. Especially when the lights at the front of the car are involved, this question proves to have many facets. A

  3. Comparing five front-of-pack nutrition labels' influence on consumers' perceptions and purchase intentions.

    Science.gov (United States)

    Gorski Findling, Mary T; Werth, Paul M; Musicus, Aviva A; Bragg, Marie A; Graham, Dan J; Elbel, Brian; Roberto, Christina A

    2018-01-01

    In 2011, a National Academy of Medicine report recommended that packaged food in the U.S. display a uniform front-of-package nutrition label, using a system such as a 0-3 star ranking. Few studies have directly compared this to other labels to determine which best informs consumers and encourages healthier purchases. In 2013, we randomized adult participants (N=1247) in an Internet-based survey to one of six conditions: no label control; single traffic light; multiple traffic light; Facts Up Front; NuVal; or 0-3 star ranking. We compared groups on purchase intentions and accuracy of participants' interpretation of food labels. There were no differences in the nutritional quality of hypothetical shopping baskets across conditions (p=0.845). All labels improved consumers' abilities to judge the nutritional quality of foods relative to no label, but the best designs varied by outcomes. NuVal and multiple traffic light labels led to the greatest accuracy identifying the healthier of two products (pFront labels led to the most accurate calories per serving estimations (pfront-of-package labels helped participants more accurately assess products' nutrition information relative to no label, no conditions shifted adults' purchase intentions. Results did not point to a clearly superior label design, but they suggest that a 3-star label might not be best for educating consumers. Copyright © 2017 Elsevier Inc. All rights reserved.

  4. Modeling of light propagation in the human neck for diagnoses of thyroid cancers by diffuse optical tomography.

    Science.gov (United States)

    Fujii, H; Yamada, Y; Kobayashi, K; Watanabe, M; Hoshi, Y

    2017-05-01

    Diffuse optical tomography using near-infrared light in a wavelength range from 700 to 1000 nm has the potential to enable non-invasive diagnoses of thyroid cancers; some of which are difficult to detect by conventional methods such as ultrasound tomography. Diffuse optical tomography needs to be based on a physically accurate model of light propagation in the neck, because it reconstructs tomographic images of the optical properties in the human neck by inverse analysis. Our objective here was to investigate the effects of three factors on light propagation in the neck using the 2D time-dependent radiative transfer equation: (1) the presence of the trachea, (2) the refractive-index mismatch at the trachea-tissue interface, and (3) the effect of neck organs other than the trachea (spine, spinal cord, and blood vessels). There was a significant influence of reflection and refraction at the trachea-tissue interface on the light intensities in the region between the trachea and the front of the neck surface. Organs other than the trachea showed little effect on the light intensities measured at the front of the neck surface although these organs affected the light intensities locally. These results indicated the necessity of modeling the refractive-index mismatch at the trachea-tissue interface and the possibility of modeling other neck organs simply as a homogeneous medium when the source and detectors were far from large blood vessels. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Airborne Light Detection and Ranging (lidar) Derived Deformation from the MW 6.0 24 August, 2014 South Napa Earthquake Estimated by Two and Three Dimensional Point Cloud Change Detection Techniques

    Science.gov (United States)

    Lyda, A. W.; Zhang, X.; Glennie, C. L.; Hudnut, K.; Brooks, B. A.

    2016-06-01

    Remote sensing via LiDAR (Light Detection And Ranging) has proven extremely useful in both Earth science and hazard related studies. Surveys taken before and after an earthquake for example, can provide decimeter-level, 3D near-field estimates of land deformation that offer better spatial coverage of the near field rupture zone than other geodetic methods (e.g., InSAR, GNSS, or alignment array). In this study, we compare and contrast estimates of deformation obtained from different pre and post-event airborne laser scanning (ALS) data sets of the 2014 South Napa Earthquake using two change detection algorithms, Iterative Control Point (ICP) and Particle Image Velocimetry (PIV). The ICP algorithm is a closest point based registration algorithm that can iteratively acquire three dimensional deformations from airborne LiDAR data sets. By employing a newly proposed partition scheme, "moving window," to handle the large spatial scale point cloud over the earthquake rupture area, the ICP process applies a rigid registration of data sets within an overlapped window to enhance the change detection results of the local, spatially varying surface deformation near-fault. The other algorithm, PIV, is a well-established, two dimensional image co-registration and correlation technique developed in fluid mechanics research and later applied to geotechnical studies. Adapted here for an earthquake with little vertical movement, the 3D point cloud is interpolated into a 2D DTM image and horizontal deformation is determined by assessing the cross-correlation of interrogation areas within the images to find the most likely deformation between two areas. Both the PIV process and the ICP algorithm are further benefited by a presented, novel use of urban geodetic markers. Analogous to the persistent scatterer technique employed with differential radar observations, this new LiDAR application exploits a classified point cloud dataset to assist the change detection algorithms. Ground

  6. AIRBORNE LIGHT DETECTION AND RANGING (LIDAR DERIVED DEFORMATION FROM THE MW 6.0 24 AUGUST, 2014 SOUTH NAPA EARTHQUAKE ESTIMATED BY TWO AND THREE DIMENSIONAL POINT CLOUD CHANGE DETECTION TECHNIQUES

    Directory of Open Access Journals (Sweden)

    A. W. Lyda

    2016-06-01

    Full Text Available Remote sensing via LiDAR (Light Detection And Ranging has proven extremely useful in both Earth science and hazard related studies. Surveys taken before and after an earthquake for example, can provide decimeter-level, 3D near-field estimates of land deformation that offer better spatial coverage of the near field rupture zone than other geodetic methods (e.g., InSAR, GNSS, or alignment array. In this study, we compare and contrast estimates of deformation obtained from different pre and post-event airborne laser scanning (ALS data sets of the 2014 South Napa Earthquake using two change detection algorithms, Iterative Control Point (ICP and Particle Image Velocimetry (PIV. The ICP algorithm is a closest point based registration algorithm that can iteratively acquire three dimensional deformations from airborne LiDAR data sets. By employing a newly proposed partition scheme, “moving window,” to handle the large spatial scale point cloud over the earthquake rupture area, the ICP process applies a rigid registration of data sets within an overlapped window to enhance the change detection results of the local, spatially varying surface deformation near-fault. The other algorithm, PIV, is a well-established, two dimensional image co-registration and correlation technique developed in fluid mechanics research and later applied to geotechnical studies. Adapted here for an earthquake with little vertical movement, the 3D point cloud is interpolated into a 2D DTM image and horizontal deformation is determined by assessing the cross-correlation of interrogation areas within the images to find the most likely deformation between two areas. Both the PIV process and the ICP algorithm are further benefited by a presented, novel use of urban geodetic markers. Analogous to the persistent scatterer technique employed with differential radar observations, this new LiDAR application exploits a classified point cloud dataset to assist the change detection

  7. Multigrid preconditioned conjugate-gradient method for large-scale wave-front reconstruction.

    Science.gov (United States)

    Gilles, Luc; Vogel, Curtis R; Ellerbroek, Brent L

    2002-09-01

    We introduce a multigrid preconditioned conjugate-gradient (MGCG) iterative scheme for computing open-loop wave-front reconstructors for extreme adaptive optics systems. We present numerical simulations for a 17-m class telescope with n = 48756 sensor measurement grid points within the aperture, which indicate that our MGCG method has a rapid convergence rate for a wide range of subaperture average slope measurement signal-to-noise ratios. The total computational cost is of order n log n. Hence our scheme provides for fast wave-front simulation and control in large-scale adaptive optics systems.

  8. Implementation of Low-Cost UHF RFID Reader Front-Ends with Carrier Leakage Suppression Circuit

    Directory of Open Access Journals (Sweden)

    Bin You

    2013-01-01

    Full Text Available A new ultrahigh frequency radio frequency identification (UHF RFID reader’s front-end circuit which is based on zero-IF, single antenna structure and composed of discrete components has been designed. The proposed design brings a significant improvement of the reading performance by adopting a carrier leakage suppression (CLS circuit instead of a circulator which is utilized by most of the conventional RF front-end circuit. Experimental results show that the proposed design improves both the sensitivity and detection range compared to the conventional designs.

  9. Planar microlens with front-face angle: design, fabrication, and characterization

    Science.gov (United States)

    Al Hafiz, Md. Abdullah; Michael, Aron; Kwok, Chee-Yee

    2016-07-01

    This paper studies the effect of microlens front-face angle on the performance of an optical system consisting of a planar-graded refractive index (GRIN) lens pair facing each other separated by a free-space region. The planar silica microlens pairs are designed to facilitate low-loss optical signal propagation in the free-space region between the opposing optical waveguides. The planar lens is fabricated from a 38-μm-thick fluorine-doped silica layer on a silicon substrate. It has a parabolic refractive index profile in the vertical direction, which is achieved by controlled fluorine incorporation in the silica film to collimate the optical beam in the vertical direction. Horizontal beam collimation is achieved by incorporating a horizontal curvature at the front face of the lens defined by deep oxide etch. A generalized 3×3 ABCDGH transformation matrix method has been derived to compute the coupling efficiency of such microlens pairs to take front-face angles that may be present due to fabrication variations or limitations and possible input/output optical fiber offset/tilt into considerations. Pairs of such planar GRIN lens with various free-space propagation distances between them ranging from 75 to 2500 μm and with front-face angles of 1.5 deg, 2 deg, and 4 deg have been fabricated and characterized. Beam propagation method simulations have been carried out to substantiate the theoretical and experimental results. The results indicate that the optical loss is reasonably low up to 1.5 deg of front-face angles and increases significantly with further increase in the front-face angle. Analysis shows that for a given system with specific microlens front-face angle, the optical loss can be significantly reduced by properly compensating the vertical position of the input and output fibers.

  10. Planar microlens with front-face angle: design, fabrication, and characterization

    KAUST Repository

    Hafiz, Md Abdullah Al

    2016-07-08

    This paper studies the effect of microlens front-face angle on the performance of an optical system consisting of a planar-graded refractive index (GRIN) lens pair facing each other separated by a free-space region. The planar silica microlens pairs are designed to facilitate low-loss optical signal propagation in the free-space region between the opposing optical waveguides. The planar lens is fabricated from a 38-μm-thick fluorine-doped silica layer on a silicon substrate. It has a parabolic refractive index profile in the vertical direction, which is achieved by controlled fluorine incorporation in the silica film to collimate the optical beam in the vertical direction. Horizontal beam collimation is achieved by incorporating a horizontal curvature at the front face of the lens defined by deep oxide etch. A generalized 3×3ABCDGH transformation matrix method has been derived to compute the coupling efficiency of such microlens pairs to take front-face angles that may be present due to fabrication variations or limitations and possible input/output optical fiber offset/tilt into considerations. Pairs of such planar GRIN lens with various free-space propagation distances between them ranging from 75 to 2500  μm and with front-face angles of 1.5 deg, 2 deg, and 4 deg have been fabricated and characterized. Beam propagation method simulations have been carried out to substantiate the theoretical and experimental results. The results indicate that the optical loss is reasonably low up to 1.5 deg of front-face angles and increases significantly with further increase in the front-face angle. Analysis shows that for a given system with specific microlens front-face angle, the optical loss can be significantly reduced by properly compensating the vertical position of the input and output fibers.

  11. Building Blocks for a 24 GHz Phased-Array Front-End in CMOS Technology for Smart Streetlights

    OpenAIRE

    Wang, Ban; Tasselli, Gabriele; Botteron, Cyril; Farine, Pierre-André

    2014-01-01

    According to a recent European Union report, lighting represents a significant share of electricity costs and the goal of reducing lighting power consumption by 20% demands the coupling of light-emitting diode (LED) lights with smart sensors and communication networks. In this context, this paper proposes the integration of these three elements into a smart streetlight, incorporating a 24 GHz phased-array (Ph-A) front-end (FE). The main building blocks of this Ph-A FE integrated in a low cost...

  12. Standing out in the crowd: The effect of information clutter on consumer attention for front-of-pack nutrition labels

    NARCIS (Netherlands)

    Bialkova, S.E.; Grunert, K.G.; Trijp, van J.C.M.

    2013-01-01

    Whether and how information density on front-of-pack design affects consumers’ attention for nutrition labels is explored. The main manipulation concerned the number and type of nutrition labels (directive-, semi-, and non-directive), chromaticity (monochrome vs. traffic light color-coded scheme);

  13. Front-of-Pack Nutrition Labels: Their Effect on Attention and Choices when Consumers have Varying Goals and Time Constraints

    NARCIS (Netherlands)

    Herpen, van E.; Trijp, van J.C.M.

    2011-01-01

    Although front-of-pack nutrition labeling can help consumers make healthier food choices, lack of attention to these labels limits their effectiveness. This study examines consumer attention to and use of three different nutrition labeling schemes (logo, multiple traffic-light label, and nutrition

  14. The front-end desaturase: structure, function, evolution and biotechnological use.

    Science.gov (United States)

    Meesapyodsuk, Dauenpen; Qiu, Xiao

    2012-03-01

    Very long chain polyunsaturated fatty acids such as arachidonic acid (ARA, 20:4n-6), eicosapentaenoic acid (EPA, 20:5n-3), docosapentaenoic acid (DPA, 22:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) are essential components of cell membranes, and are precursors for a group of hormone-like bioactive compounds (eicosanoids and docosanoids) involved in regulation of various physiological activities in animals and humans. The biosynthesis of these fatty acids involves an alternating process of fatty acid desaturation and elongation. The desaturation is catalyzed by a unique class of oxygenases called front-end desaturases that introduce double bonds between the pre-existing double bond and the carboxyl end of polyunsaturated fatty acids. The first gene encoding a front-end desaturase was cloned in 1993 from cyanobacteria. Since then, front-end desaturases have been identified and characterized from a wide range of eukaryotic species including algae, protozoa, fungi, plants and animals including humans. Unlike front-end desaturases from bacteria, those from eukaryotes are structurally characterized by the presence of an N-terminal cytochrome b₅-like domain fused to the main desaturation domain. Understanding the structure, function and evolution of front-end desaturases, as well as their roles in the biosynthesis of very long chain polyunsaturated fatty acids offers the opportunity to engineer production of these fatty acids in transgenic oilseed plants for nutraceutical markets.

  15. Direct drive ablation front stability: numerical predictions against flame front model

    Energy Technology Data Exchange (ETDEWEB)

    Masse, L. [Phd Student at IRPHE St Jerome, 13 - Marseille (France)]|[CEA/DAM-Ile de France, 91 - Bruyeres Le Chatel (France); Hallo, L.; Tallot, C. [CEA/DAM-Ile de France, 91 - Bruyeres Le Chatel (France)

    2000-07-01

    We study the linear stability of flows resulting from constant heating of planar targets by a laser. In the coordinate system of the ablation front there is a flow from the cold to hot region, which is situated in a gravity field oriented from hot to cold region. Similar types of flow can be observed in combustion systems, which involve propagation of flame fronts. A spectral model which studies linear perturbation is directly taken from the combustion community. Here we present the results for state as well as perturbed flows. Growth rate determined from the models are compared to each other, and preliminary numerical results from FC12 simulations are shown. (authors)

  16. Kommuner i front - organisationsudvikling blandt kommunale socialforvaltninger

    DEFF Research Database (Denmark)

    Gregersen, Ole

    Det er næsten et princip, at Folketinget i udformningen af sociallovgivningen ikke blander sig i, hvordan kommunerne skal organisere arbejdet med at føre lovgivningen ud i livet. Det er midlertid oplagt, at der parallelt med den lovgivningsmæssige udvikling sker en organisatorisk udvikling blandt...... ideerne om organisationsforandring er her, at nye organisatoriske elementer spredes fra nogle få pionerer til resten (eller en stor andel af resten) af kommunerne. Et af de interessante spørgsmål i forlængelse af denne tankegang er, om det altid er de samme kommuner, der går i front med...

  17. Fact Sheet for KM200 Front-end Electronics

    Energy Technology Data Exchange (ETDEWEB)

    Ianakiev, Kiril Dimitrov [Los Alamos National Laboratory; Iliev, Metodi [Los Alamos National Laboratory; Swinhoe, Martyn Thomas [Los Alamos National Laboratory

    2015-07-08

    The KM200 device is a versatile, configurable front-end electronics boards that can be used as a functional replacement for Canberra’s JAB-01 boards based on the Amptek A-111 hybrid chip, which continues to be the preferred choice of electronics for large number of the boards in junction boxes of multiplicity counters that process the signal from an array of 3He detectors. Unlike the A-111 chip’s fixed time constants and sensitivity range, the shaping time and sensitivity of the new KM200 can be optimized for demanding applications such as spent fuel, and thus could improve the safeguards measurements of existing systems where the A-111 or PDT electronics does not perform well.

  18. Reaction-Transport Systems Mesoscopic Foundations, Fronts, and Spatial Instabilities

    CERN Document Server

    Horsthemke, Werner; Mendez, Vicenc

    2010-01-01

    This book is an introduction to the dynamics of reaction-diffusion systems, with a focus on fronts and stationary spatial patterns. Emphasis is on systems that are non-standard in the sense that either the transport is not simply classical diffusion (Brownian motion) or the system is not homogeneous. A important feature is the derivation of the basic phenomenological equations from the mesoscopic system properties. Topics addressed include transport with inertia, described by persistent random walks and hyperbolic reaction-transport equations and transport by anomalous diffusion, in particular subdiffusion, where the mean square displacement grows sublinearly with time. In particular reaction-diffusion systems are studied where the medium is in turn either spatially inhomogeneous, compositionally heterogeneous or spatially discrete. Applications span a vast range of interdisciplinary fields and the systems considered can be as different as human or animal groups migrating under external influences, population...

  19. Front end electronics for pixel detector of the PANDA MVD

    CERN Document Server

    Kugathasan, Thanushan; De Remigis, P; Mazza, G; Mignone, M; Rivetti, A; Wheadon, R

    2009-01-01

    ToPix 2.0 is a prototype in a CMOS 0.13 ¹m technology of the front-end chip for the hybrid pixel sensors that will equip the Micro-Vertex Detector of the PANDA experiment at GSI. The Time over Threshold (ToT) approach has been employed to provide a high charge dynamic range (up to 100 fC) with a low power dissipation (15 ¹W/cell). In an area of 100¹m£100¹m each cell incorporates the analog and digital electronics necessary to amplify the detector signal and to digitize the time and charge information. The ASIC includes 320 pixel readout cells organized in four columns and a simplified version of the end of column readout.

  20. Light Sources and Lighting Circuits

    Science.gov (United States)

    Honda, Hisashi; Suwa, Takumi; Yasuda, Takeo; Ohtani, Yoshihiko; Maehara, Akiyoshi; Okada, Atsunori; Komatsu, Naoki; Mannami, Tomoaki

    means of using filler gas with a higher atomic weight. Regarding fluorescent lamps, studies and developments for longer operating life and improvement in the lumen maintenance factor for the straight-type and circular-type fluorescent lamps were actively pursued. Regarding self-ballasted fluorescent lamps, the main stream of development was aimed at reducing lamp size and increasing energy conservation, and the development of new products that took advantage of these features proceeded. In regard to LED light sources, basic research and product development, including new application development, were vigorously implemented. In basic research, studies were reported, not only on efficacy improvements through optimization of the LED chips, phosphor layers, and packaging technology, but also on photometry, colorimetry, and visual psychology. In the field of application, applications were studied for general lighting sources and also for a wide range of fields, such as automotive headlights and visible light communication. Also, many academic conferences and exhibitions were held domestically and overseas, and the high level of interest suggests high expectations for this next-generation light source. Regarding HID lamps, there was much activity in research and development and in the commercialization of the ceramic metal halide lamp product, and products were commercialized with features such as higher efficiency (130 lm/W) and higher color rendering properties (R9 ≥ 90). In the high-pressure sodium lamps, there were many study reports concerning plant growth and insect pest control using its low insect-attracting characteristics. With high-pressure mercury lamps, there were many reports on reducing lamp size and increasing intensity for use as a light source for projectors.

  1. Negative Lens–Induced Myopia in Infant Monkeys: Effects of High Ambient Lighting

    Science.gov (United States)

    Smith, Earl L.; Hung, Li-Fang; Arumugam, Baskar; Huang, Juan

    2013-01-01

    Purpose. To determine whether high light levels, which have a protective effect against form-deprivation myopia, also retard the development of lens-induced myopia in primates. Methods. Hyperopic defocus was imposed on 27 monkeys by securing −3 diopter (D) lenses in front of one eye. The lens-rearing procedures were initiated at 24 days of age and continued for periods ranging from 50 to 123 days. Fifteen of the treated monkeys were exposed to normal laboratory light levels (∼350 lux). For the other 12 lens-reared monkeys, auxiliary lighting increased the illuminance to 25,000 lux for 6 hours during the middle of the daily 12 hour light cycle. Refractive development, corneal power, and axial dimensions were assessed by retinoscopy, keratometry, and ultrasonography, respectively. Data were also obtained from 37 control monkeys, four of which were exposed to high ambient lighting. Results. In normal- and high-light-reared monkeys, hyperopic defocus accelerated vitreous chamber elongation and produced myopic shifts in refractive error. The high light regimen did not alter the degree of myopia (high light: −1.69 ± 0.84 D versus normal light: −2.08 ± 1.12 D; P = 0.40) or the rate at which the treated eyes compensated for the imposed defocus. Following lens removal, the high light monkeys recovered from the induced myopia. The recovery process was not affected by the high lighting regimen. Conclusions. In contrast to the protective effects that high ambient lighting has against form-deprivation myopia, high artificial lighting did not alter the course of compensation to imposed defocus. These results indicate that the mechanisms responsible for form-deprivation myopia and lens-induced myopia are not identical. PMID:23557736

  2. Negative lens-induced myopia in infant monkeys: effects of high ambient lighting.

    Science.gov (United States)

    Smith, Earl L; Hung, Li-Fang; Arumugam, Baskar; Huang, Juan

    2013-04-26

    To determine whether high light levels, which have a protective effect against form-deprivation myopia, also retard the development of lens-induced myopia in primates. Hyperopic defocus was imposed on 27 monkeys by securing -3 diopter (D) lenses in front of one eye. The lens-rearing procedures were initiated at 24 days of age and continued for periods ranging from 50 to 123 days. Fifteen of the treated monkeys were exposed to normal laboratory light levels (∼350 lux). For the other 12 lens-reared monkeys, auxiliary lighting increased the illuminance to 25,000 lux for 6 hours during the middle of the daily 12 hour light cycle. Refractive development, corneal power, and axial dimensions were assessed by retinoscopy, keratometry, and ultrasonography, respectively. Data were also obtained from 37 control monkeys, four of which were exposed to high ambient lighting. in normal- and high-light-reared monkeys, hyperopic defocus accelerated vitreous chamber elongation and produced myopic shifts in refractive error. the high light regimen did not alter the degree of myopia (high light: -1.69 ± 0.84 D versus normal light: -2.08 ± 1.12 D; P = 0.40) or the rate at which the treated eyes compensated for the imposed defocus. Following lens removal, the high light monkeys recovered from the induced myopia. The recovery process was not affected by the high lighting regimen. In contrast to the protective effects that high ambient lighting has against form-deprivation myopia, high artificial lighting did not alter the course of compensation to imposed defocus. These results indicate that the mechanisms responsible for form-deprivation myopia and lens-induced myopia are not identical.

  3. Efficient nanorod-based amorphous silicon solar cells with advanced light trapping

    Science.gov (United States)

    Kuang, Y.; van Lare, M. C.; Veldhuizen, L. W.; Polman, A.; Rath, J. K.; Schropp, R. E. I.

    2015-11-01

    We present a simple, low-cost, and scalable approach for the fabrication of efficient nanorod-based solar cells. Templates with arrays of self-assembled ZnO nanorods with tunable morphology are synthesized by chemical bath deposition using a low process temperature at 80 °C. The nanorod templates are conformally coated with hydrogenated amorphous silicon light absorber layers of 100 nm and 200 nm thickness. An initial efficiency of up to 9.0% is achieved for the optimized design. External quantum efficiency measurements on the nanorod cells show a substantial photocurrent enhancement both in the red and the blue parts of the solar spectrum. Key insights in the light trapping mechanisms in these arrays are obtained via a combination of three-dimensional finite-difference time-domain simulations, optical absorption, and external quantum efficiency measurements. Front surface patterns enhance the light incoupling in the blue, while rear side patterns lead to enhanced light trapping in the red. The red response in the nanorod cells is limited by absorption in the patterned Ag back contact. With these findings, we develop and experimentally realize a further advanced design with patterned front and back sides while keeping the Ag reflector flat, showing significantly enhanced scattering from the back reflector with reduced parasitic absorption in the Ag and thus higher photocurrent generation. Many of the findings in this work can serve to provide insights for further optimization of nanostructures for thin-film solar cells in a broad range of materials.

  4. AFEII Analog Front End Board Design Specifications

    Energy Technology Data Exchange (ETDEWEB)

    Rubinov, Paul; /Fermilab

    2005-04-01

    This document describes the design of the 2nd iteration of the Analog Front End Board (AFEII), which has the function of receiving charge signals from the Central Fiber Tracker (CFT) and providing digital hit pattern and charge amplitude information from those charge signals. This second iteration is intended to address limitations of the current AFE (referred to as AFEI in this document). These limitations become increasingly deleterious to the performance of the Central Fiber Tracker as instantaneous luminosity increases. The limitations are inherent in the design of the key front end chips on the AFEI board (the SVXIIe and the SIFT) and the architecture of the board itself. The key limitations of the AFEI are: (1) SVX saturation; (2) Discriminator to analog readout cross talk; (3) Tick to tick pedestal variation; and (4) Channel to channel pedestal variation. The new version of the AFE board, AFEII, addresses these limitations by use of a new chip, the TriP-t and by architectural changes, while retaining the well understood and desirable features of the AFEI board.

  5. Internal waves and temperature fronts on slopes

    Directory of Open Access Journals (Sweden)

    S. A. Thorpe

    Full Text Available Time series measurements from an array of temperature miniloggers in a line at constant depth along the sloping boundary of a lake are used to describe the `internal surf zone' where internal waves interact with the sloping boundary. More small positive temperature time derivatives are recorded than negative, but there are more large negative values than positive, giving the overall distribution of temperature time derivatives a small negative skewness. This is consistent with the internal wave dynamics; fronts form during the up-slope phase of the motion, bringing cold water up the slope, and the return flow may become unstable, leading to small advecting billows and weak warm fronts. The data are analysed to detect `events', periods in which the temperature derivatives exceed a set threshold. The speed and distance travelled by `events' are described. The motion along the slope may be a consequence of (a instabilities advected by the flow (b internal waves propagating along-slope or (c internal waves approaching the slope from oblique directions. The propagation of several of the observed 'events' can only be explained by (c, evidence that the internal surf zone has some, but possibly not all, the characteristics of the conventional 'surface wave' surf zone, with waves steepening as they approach the slope at oblique angles.

    Key words. Oceanography: general (benthic boundary layers; limnology, Oceanography: physical (internal and inertial waves

  6. Universal Millimeter-Wave Radar Front End

    Science.gov (United States)

    Perez, Raul M.

    2010-01-01

    A quasi-optical front end allows any arbitrary polarization to be transmitted by controlling the timing, amplitude, and phase of the two input ports. The front end consists of two independent channels horizontal and vertical. Each channel has two ports transmit and receive. The transmit signal is linearly polarized so as to pass through a periodic wire grid. It is then propagated through a ferrite Faraday rotator, which rotates the polarization state 45deg. The received signal is propagated through the Faraday rotator in the opposite direction, undergoing a further 45 of polarization rotation due to the non-reciprocal action of the ferrite under magnetic bias. The received signal is now polarized at 90deg relative to the transmit signal. This signal is now reflected from the wire grid and propagated to the receive port. The horizontal and vertical channels are propagated through, or reflected from, another wire grid. This design is an improvement on the state of the art in that any transmit signal polarization can be chosen in whatever sequence desired. Prior systems require switching of the transmit signal from the amplifier, either mechanically or by using high-power millimeter-wave switches. This design can have higher reliability, lower mass, and more flexibility than mechanical switching systems, as well as higher reliability and lower losses than systems using high-power millimeter-wave switches.

  7. Travelling fronts in stochastic Stokes’ drifts

    KAUST Repository

    Blanchet, Adrien

    2008-10-01

    By analytical methods we study the large time properties of the solution of a simple one-dimensional model of stochastic Stokes\\' drift. Semi-explicit formulae allow us to characterize the behaviour of the solutions and compute global quantities such as the asymptotic speed of the center of mass or the effective diffusion coefficient. Using an equivalent tilted ratchet model, we observe that the speed of the center of mass converges exponentially to its limiting value. A diffuse, oscillating front attached to the center of mass appears. The description of the front is given using an asymptotic expansion. The asymptotic solution attracts all solutions at an algebraic rate which is determined by the effective diffusion coefficient. The proof relies on an entropy estimate based on homogenized logarithmic Sobolev inequalities. In the travelling frame, the macroscopic profile obeys to an isotropic diffusion. Compared with the original diffusion, diffusion is enhanced or reduced, depending on the regime. At least in the limit cases, the rate of convergence to the effective profile is always decreased. All these considerations allow us to define a notion of efficiency for coherent transport, characterized by a dimensionless number, which is illustrated on two simple examples of travelling potentials with a sinusoidal shape in the first case, and a sawtooth shape in the second case. © 2008 Elsevier B.V. All rights reserved.

  8. An island in front of Izola

    Directory of Open Access Journals (Sweden)

    Franci Steinman

    2002-01-01

    Full Text Available Maritime construction in front of Izola restitutes an enriched former state. The island is positioned in a place where there are no legal regimes enforced by the state or local community. Legal regimes that determine the exploitation of water rights and limitations (management, exploitation, use can actually limit all. Therefore their synthesis has to be the starting point for analysing the harmony of present uses and for planning future uses of the sea and coastal area. For example the aquatorium of the shellfish mariculture positioned in the Strunjan Bay without adequate analysis of the prevailing conditions is causing conflicts of uses, unacceptable limiting of general use of the sea and prohibitive limitations in neighbouring areas. The analysis done for the island in front of Izola shows that there are no such consequences. Only uses in the public interest were proposed, since when assessing suitability first public and then common interests where considered, possible specific (e.g. entrepreneurial uses were permitted only if the afore mentioned weren’t obstructed. Thus integral management of the coastal area was enabled, with respect to functional ties between the land and sea.

  9. The ALICE TPC front end electronics

    CERN Document Server

    Musa, L; Bialas, N; Bramm, R; Campagnolo, R; Engster, Claude; Formenti, F; Bonnes, U; Esteve-Bosch, R; Frankenfeld, Ulrich; Glässel, P; Gonzales, C; Gustafsson, Hans Åke; Jiménez, A; Junique, A; Lien, J; Lindenstruth, V; Mota, B; Braun-Munzinger, P; Oeschler, H; Österman, L; Renfordt, R E; Ruschmann, G; Röhrich, D; Schmidt, H R; Stachel, J; Soltveit, A K; Ullaland, K

    2004-01-01

    In this paper we present the front end electronics for the time projection chamber (TPC) of the ALICE experiment. The system, which consists of about 570000 channels, is based on two basic units: (a) an analogue ASIC (PASA) that incorporates the shaping-amplifier circuits for 16 channels; (b) a mixed-signal ASIC (ALTRO) that integrates 16 channels, each consisting of a 10-bit 25-MSPS ADC, the baseline subtraction, tail cancellation filter, zero suppression and multi-event buffer. The complete readout chain is contained in front end cards (FEC), with 128 channels each, connected to the detector by means of capton cables. A number of FECs (up to 25) are controlled by a readout control unit (RCU), which interfaces the FECs to the data acquisition (DAQ), the trigger, and the detector control system (DCS) . A function of the final electronics (1024 channels) has been characterized in a test that incorporates a prototype of the ALICE TPC as well as many other components of the final set-up. The tests show that the ...

  10. Non-invasive three-dimension control of light between turbid layers using a surface quasi-point light source for precorrection.

    Science.gov (United States)

    Qiao, Mu; Liu, Honglin; Pang, Guanghui; Han, Shensheng

    2017-08-29

    Manipulating light non-invasively through inhomogeneous media is an attractive goal in many disciplines. Wavefront shaping and optical phase conjugation can focus light to a point. Transmission matrix method can control light on multiple output modes simultaneously. Here we report a non-invasive approach which enables three-dimension (3D) light control between two turbid layers. A digital optical phase conjugation mirror measured and conjugated the diffused wavefront, which originated from a quasi-point source on the front turbid layer and passed through the back turbid layer. And then, because of memory effect, the phase-conjugated wavefront could be used as a carrier wave to transport a pre-calculated wavefront through the back turbid layer. The pre-calculated wavefront could project a desired 3D light field inside the sample, which, in our experiments, consisted of two 220-grid ground glass plates spaced by a 20 mm distance. The controllable range of light, according to the memory effect, was calculated to be 80 mrad in solid angle and 16 mm on z-axis. Due to the 3D light control ability, our approach may find applications in photodynamic therapy and optogenetics. Besides, our approach can also be combined with ghost imaging or compressed sensing to achieve 3D imaging between turbid layers.

  11. Performance evaluation of a computed radiography imaging device using a typical "front side" and novel "dual side" readout storage phosphors.

    Science.gov (United States)

    Fetterly, Kenneth A; Schueler, Beth A

    2006-02-01

    The Fourier-space modulation transfer function (MTF), normalized noise power spectrum (nNPS), and detective quantum efficiency (DQE) of a computed radiography (CR) x-ray imaging device were measured. Two different storage phosphor screens were used in conjunction with a single CR reader (Fuji, Clearview, CS). One of the storage phosphor plates (ST-BD) had a clear backing material which allowed "dual side read" of the latent image from both the "front" and "back" sides of the phosphor. The other phosphor plate had a light occluding backing material, limiting the readout to front side only (ST-VI). The standard RQA-5 beam quality was used. The MTF was measured using a 1 mm thick tungsten edge device. Compared to the ST-55BD phosphor, the ST-VI phosphor was found to have modestly higher MTF at all spatial frequencies. The nNPS(f) and DQE(f) were measured for nominal incident exposure levels ranging from 0.1 to 10 mR. The dual side read phosphor demonstrated superior DQE, especially at low spatial frequencies. At the frequency 0.5 cycles/mm, the DQE values for the 1 mR exposure were 0.36 and 0.21 for the ST-55BD and ST-VI phosphor plates, respectively. The differences between the spatial-frequency dependent DQE of the two plates can be attributed to the increased signal collection efficiency of the dual side read plates and differences in storage phosphor structure noise.

  12. Control of Surface Plasmon Resonance of Au/SnO2 by Modification with Ag and Cu for Photoinduced Reactions under Visible-Light Irradiation over a Wide Range.

    Science.gov (United States)

    Tanaka, Atsuhiro; Hashimoto, Keiji; Kominami, Hiroshi

    2016-03-18

    Gold particles supported on tin(IV) oxide (0.2 wt% Au/SnO2) were modified with copper and silver by the multistep photodeposition method. Absorption around λ=550 nm, attributed to surface plasmon resonance (SPR) of Au, gradually shifted to longer wavelengths on modification with Cu and finally reached λ=620 nm at 0.8 wt% Cu. On the other hand, the absorption shifted to shorter wavelength with increasing amount of Ag and reached λ=450 nm at 0.8 wt% Ag. These Cu- and Ag-modified 0.2 wt% Au/SnO2 materials (Cu-Au/SnO2 and Ag-Au/SnO2) and 1.0 wt% Au/SnO2 were used for mineralization of formic acid to carbon dioxide in aqueous suspension under irradiation with visible light from a xenon lamp and three kinds of light-emitting diodes with different wavelengths. The reaction rates for the mineralization of formic acid over these materials depend on the wavelength of light. Apparent quantum efficiencies of Cu-Au/SnO2, Au/SnO2, and Ag-Au/SnO2 reached 5.5% at 625 nm, 5.8% at 525 nm, and 5.1% at 450 nm, respectively. These photocatalysts can also be used for selective oxidation of alcohols to corresponding carbonyl compounds in aqueous solution under visible-light irradiation. Broad responses to visible light in formic acid mineralization and selective alcohol oxidation were achieved when the three materials were used simultaneously. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Light Pollution

    Science.gov (United States)

    Riegel, Kurt W.

    1973-01-01

    Outdoor lighting is light pollution which handicaps certain astronomical programs. Protective measures must be adopted by the government to aid observational astronomy without sacrificing legitimate outdoor lighting needs. (PS)

  14. Vegetation map of the greater Denver area, Front Range urban corridor, Colorado

    Science.gov (United States)

    Marr, J.W.; Boyd, W.S.

    1979-01-01

    Vegetation is one of our most valuable renewable resources; it is the primary producer of organic matter on which all nongreen organisms are dependent for energy, construction materials, aesthetic enjoyment, and other necessities of life. In order to secure the greatest possible returns from the utilization of the different types of vegetation, people need to know what species are present, the ecological processes in which they are involved, and the ways in which they are arranged in the landscape. This vegetation map is designed to help persons in a wide variety of activities to secure that information.

  15. Source Definition Issue for KN Power - Front Range Energy Associates, LLC/PSCo Generating Facility

    Science.gov (United States)

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  16. Natural hazard understanding in the middle schools of the Colorado Front Range

    Energy Technology Data Exchange (ETDEWEB)

    Grogger, P.K. [Univ. of Colorado, Colorado Springs, CO (United States). Dept. of Geology

    1995-12-01

    The best form of mitigation is not to put one`s self in a position that mitigation is required. For the last five years the University of Colorado`s Department of Geology has teamed with local school districts to implement an understanding of natural hazards. By working with middle school students the dangers and possible mitigation of North America are learned at an early age. Over the years, the knowledge gained by these communities citizens will hopefully help lessen the dangers from natural hazards society faces. Education of the general public about natural hazards needs to be addressed by the professional societies studying and developing answers to natural hazards problems. By working with school children this process of educating the general public starts early in the education system and will bear fruit many years in the future. This paper describes the course that is being given to students in Colorado.

  17. Rehabilitating slash pile burn scars in upper montane forests of the Colorado Front Range

    Science.gov (United States)

    Paula J. Fornwalt; Charles C. Rhoades

    2011-01-01

    Slash pile burning is widely conducted by land managers to dispose of unwanted woody fuels, yet this practice typically has undesirable ecological impacts. Simple rehabilitation treatments may be effective at ameliorating some of the negative impacts of pile burning on plants and soils. Here, we investigated: (1) the impacts of slash pile burning on soil nitrogen and...

  18. Recovery of small pile burn scars in conifer forests of the Colorado Front Range

    Science.gov (United States)

    Charles C. Rhoades; Paula J. Fornwalt; Mark W. Paschke; Amber Shanklin; Jayne L. Jonas

    2015-01-01

    The ecological consequences of slash pile burning are a concern for land managers charged with maintaining forest soil productivity and native plant diversity. Fuel reduction and forest health management projects have created nearly 150,000 slash piles scheduled for burning on US Forest Service land in northern Colorado. The vast majority of these are small piles (

  19. Hedonic valuation with translating amenities: Mountain Pine Beetles and host trees in the Colorado Front Range

    Science.gov (United States)

    Jed Cohen; Christine E. Blinn; Kevin J. Boyle; Tom Holmes; Klaus Moeltner

    2016-01-01

    In hedonic valuation studies the policy-relevant environmental quality attribute of interest is often costly to measure, especially under pronounced spatial and temporal variability. However, in many cases this attribute affects home prices and consumer preferences solely through its impact on a readily observable, spatially delineated, and time-invariant feature of...

  20. Hydrochemical responses to climate change in high-elevation catchments of the Colorado Front Range. (Invited)

    Science.gov (United States)

    Williams, M. W.

    2009-12-01

    Potential climate impacts on the hydrochemistry of two seasonally snow covered catchments is evaluated using 24 years of data from the Niwot Ridge Long Term Ecological Research Site, Colorado. At the larger (220 ha), higher elevation (3570 m) GL4 catchment annual discharge did not change significantly based on nonparametric trend testing. However, October streaflow volumes and groundwater storage did increase, despite drought conditions near the end of the record in 2000-2004. In contrast, at the smaller (8 ha), lower elevation (3400 m) MART catchment, annual discharge decreased significantly over the study period with the most substantial changes in July-September. The study period was separated into "wet", "normal", and "dry" years based on the 75th and 25th quartiles of annual precipitation. Results indicate that MART is particularly sensitive to changes in precipitation with dry years exhibiting decreased snowmelt peak flows, earlier snowmelt timing, decreased annual discharge, and reduced late-season flows. GL4 was less susceptible to changes in precipitation and surprisingly late-season flow volumes (Sept.-Oct.) were not significantly different between wet, normal, and dry conditions. Surprisingly, during dry years both the concentrations and annual fluxes of Ca2+ and SO42- increased in the outflow of GL4, but not at the Martinelli catchment. These changes in hydrochemistry were particularly pronounced during the low-flow period. Streamwater chemistry in GL4 during drought years resembled that of permafrost, suggesting augmented flow during the fall due to permafrost melt. This study shows that seasonally snow covered catchments are particularly sensitive to changes in climate, but the hydrochemical response may depend on landscape characteristics.