Spatially Fourier-encoded photoacoustic microscopy using a digital micromirror device

PubMed Central

Liang, Jinyang; Gao, Liang; Li, Chiye; Wang, Lihong V.

2014-01-01

We have developed spatially Fourier-encoded photoacoustic microscopy using a digital micromirror device. The spatial intensity distribution of laser pulses is Fourier-encoded, and a series of such encoded photoacoustic measurements allows one to decode the spatial distribution of optical absorption. The throughput and Fellgett advantages were demonstrated by imaging a chromium target. By using 63 spatial elements, the signal-to-noise ratio in the recovered photoacoustic signal was enhanced by ~4×. The system was used to image two biological targets, a monolayer of red blood cells and melanoma cells. PMID:24487832

Sodium Atoms in the Lunar Exotail: Observed Velocity and Spatial Distributions

NASA Technical Reports Server (NTRS)

Line, Michael R.; Mierkiewicz, E. J.; Oliversen, R. J.; Wilson, J. K.; Haffner, L. M.; Roesler, F. L.

2011-01-01

The lunar sodium tail extends long distances due to radiation pressure on sodium atoms in the lunar exosphere. Our earlier observations determined the average radial velocity of sodium atoms moving down the lunar tail beyond Earth along the Sun-Moon-Earth line (i.e., the anti-lunar point) to be 12.4 km/s. Here we use the Wisconsin H-alpha Mapper to obtain the first kinematically resolved maps of the intensity and velocity distribution of this emission over a 15 x times 15 deg region on the sky near the anti-lunar point. We present both spatially and spectrally resolved observations obtained over four nights around new moon in October 2007. The spatial distribution of the sodium atoms is elongated along the ecliptic with the location of the peak intensity drifting 3 degrees east along the ecliptic per night. Preliminary modeling results suggest that the spatial and velocity distributions in the sodium exotail are sensitive to the near surface lunar sodium velocity distribution and that observations of this sort along with detailed modeling offer new opportunities to describe the time history of lunar surface sputtering over several days.

Gaussian theory for spatially distributed self-propelled particles

NASA Astrophysics Data System (ADS)

Seyed-Allaei, Hamid; Schimansky-Geier, Lutz; Ejtehadi, Mohammad Reza

2016-12-01

Obtaining a reduced description with particle and momentum flux densities outgoing from the microscopic equations of motion of the particles requires approximations. The usual method, we refer to as truncation method, is to zero Fourier modes of the orientation distribution starting from a given number. Here we propose another method to derive continuum equations for interacting self-propelled particles. The derivation is based on a Gaussian approximation (GA) of the distribution of the direction of particles. First, by means of simulation of the microscopic model, we justify that the distribution of individual directions fits well to a wrapped Gaussian distribution. Second, we numerically integrate the continuum equations derived in the GA in order to compare with results of simulations. We obtain that the global polarization in the GA exhibits a hysteresis in dependence on the noise intensity. It shows qualitatively the same behavior as we find in particles simulations. Moreover, both global polarizations agree perfectly for low noise intensities. The spatiotemporal structures of the GA are also in agreement with simulations. We conclude that the GA shows qualitative agreement for a wide range of noise intensities. In particular, for low noise intensities the agreement with simulations is better as other approximations, making the GA to an acceptable candidates of describing spatially distributed self-propelled particles.

A simple method for correcting spatially resolved solar intensity oscillation observations for variations in scattered light

NASA Technical Reports Server (NTRS)

Jefferies, S. M.; Duvall, T. L., Jr.

1991-01-01

A measurement of the intensity distribution in an image of the solar disk will be corrupted by a spatial redistribution of the light that is caused by the earth's atmosphere and the observing instrument. A simple correction method is introduced here that is applicable for solar p-mode intensity observations obtained over a period of time in which there is a significant change in the scattering component of the point spread function. The method circumvents the problems incurred with an accurate determination of the spatial point spread function and its subsequent deconvolution from the observations. The method only corrects the spherical harmonic coefficients that represent the spatial frequencies present in the image and does not correct the image itself.

Exploratory study and application of the angular wavelet analysis for assessing the spatial distribution of breakdown spots in Pt/HfO2/Pt structures

NASA Astrophysics Data System (ADS)

Muñoz-Gorriz, J.; Monaghan, S.; Cherkaoui, K.; Suñé, J.; Hurley, P. K.; Miranda, E.

2017-12-01

The angular wavelet analysis is applied for assessing the spatial distribution of breakdown spots in Pt/HfO2/Pt capacitors with areas ranging from 104 to 105 μm2. The breakdown spot lateral sizes are in the range from 1 to 3 μm, and they appear distributed on the top metal electrode as a point pattern. The spots are generated by ramped and constant voltage stresses and are the consequence of microexplosions caused by the formation of shorts spanning the dielectric film. This kind of pattern was analyzed in the past using the conventional spatial analysis tools such as intensity plots, distance histograms, pair correlation function, and nearest neighbours. Here, we show that the wavelet analysis offers an alternative and complementary method for testing whether or not the failure site distribution departs from a complete spatial randomness process in the angular domain. The effect of using different wavelet functions, such as the Haar, Sine, French top hat, Mexican hat, and Morlet, as well as the roles played by the process intensity, the location of the voltage probe, and the aspect ratio of the device, are all discussed.

A simple optode based method for imaging O2 distribution and dynamics in tap water biofilms.

PubMed

Staal, M; Prest, E I; Vrouwenvelder, J S; Rickelt, L F; Kühl, M

2011-10-15

A ratiometric luminescence intensity imaging approach is presented, which enables spatial O2 measurements in biofilm reactors with transparent planar O2 optodes. Optodes consist of an O2 sensitive luminescent dye immobilized in a 1-10 μm thick polymeric layer on a transparent carrier, e.g. a glass window. The method is based on sequential imaging of the O2 dependent luminescence intensity, which are subsequently normalized with luminescent intensity images recorded under anoxic conditions. We present 2-dimensional O2 distribution images at the base of a tap water biofilm measured with the new ratiometric method and compare the results with O2 distribution images obtained in the same biofilm reactor with luminescence lifetime imaging. Using conventional digital cameras, such simple normalized luminescence intensity imaging can yield images of 2-dimensional O2 distributions with a high signal-to-noise ratio and spatial resolution comparable or even surpassing those obtained with expensive and complex luminescence lifetime imaging systems. The method can be applied to biofilm growth incubators allowing intermittent experimental shifts to anoxic conditions or in systems, in which the O2 concentration is depleted during incubation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Modeling evolution of spatially distributed bacterial communities: a simulation with the haploid evolutionary constructor

PubMed Central

2015-01-01

Background Multiscale approaches for integrating submodels of various levels of biological organization into a single model became the major tool of systems biology. In this paper, we have constructed and simulated a set of multiscale models of spatially distributed microbial communities and study an influence of unevenly distributed environmental factors on the genetic diversity and evolution of the community members. Results Haploid Evolutionary Constructor software http://evol-constructor.bionet.nsc.ru/ was expanded by adding the tool for the spatial modeling of a microbial community (1D, 2D and 3D versions). A set of the models of spatially distributed communities was built to demonstrate that the spatial distribution of cells affects both intensity of selection and evolution rate. Conclusion In spatially heterogeneous communities, the change in the direction of the environmental flow might be reflected in local irregular population dynamics, while the genetic structure of populations (frequencies of the alleles) remains stable. Furthermore, in spatially heterogeneous communities, the chemotaxis might dramatically affect the evolution of community members. PMID:25708911

BATSE analysis techniques for probing the GRB spatial and luminosity distributions

NASA Technical Reports Server (NTRS)

Hakkila, Jon; Meegan, Charles A.

1992-01-01

The Burst And Transient Source Experiment (BATSE) has measured homogeneity and isotropy parameters from an increasingly large sample of observed gamma-ray bursts (GRBs), while also maintaining a summary of the way in which the sky has been sampled. Measurement of both of these are necessary for any study of the BATSE data statistically, as they take into account the most serious observational selection effects known in the study of GRBs: beam-smearing and inhomogeneous, anisotropic sky sampling. Knowledge of these effects is important to analysis of GRB angular and intensity distributions. In addition to determining that the bursts are local, it is hoped that analysis of such distributions will allow boundaries to be placed on the true GRB spatial distribution and luminosity function. The technique for studying GRB spatial and luminosity distributions is direct. Results of BATSE analyses are compared to Monte Carlo models parameterized by a variety of spatial and luminosity characteristics.

Storm Identification and Tracking for Hydrologic Modeling Using Hourly Accumulated NEXRAD Precipitation Data

NASA Astrophysics Data System (ADS)

Olivera, F.; Choi, J.; Socolofsky, S.

2006-12-01

Watershed responses to storm events are strongly affected by the spatial and temporal patterns of rainfall; that is, the spatial distribution of the precipitation intensity and its evolution over time. Although real storms are moving entities with non-uniform intensities in both space and time, hydrological applications often synthesize these attributes by assuming storms that are uniformly distributed and have variable intensity according to a pre-defined hyetograph shape. As one considers watersheds of greater size, the non-uniformity of rainfall becomes more important, because a storm may not cover the watershed's entire area and may not stay in the watershed for its full duration. In order to incorporate parameters such as storm area, propagation velocity and direction, and intensity distribution in the definition of synthetic storms, it is necessary to determine these storm characteristics from spatially distributed precipitation data. To date, most algorithms for identifying and tracking storms have been applied to short time-step radar reflectivity data (i.e., 15 minutes or less), where storm features are captured in an effectively synoptic manner. For the entire United States, however, the most reliable distributed precipitation data are the one-hour accumulated 4 km × 4 km gridded NEXRAD data of the U.S. National Weather Service (NWS) (NWS 2005. The one-hour aggregation level of the data, though, makes it more difficult to identify and track storms than when using sequences of synoptic radar reflectivity data, because storms can traverse over a number of NEXRAD cells and change size and shape appreciably between consecutive data maps. In this paper, we present a methodology to overcome the identification and tracking difficulties and to extract the characteristics of moving storms (e.g. size, propagation velocity and direction, and intensity distribution) from one-hour accumulated distributed rainfall data. The algorithm uses Gaussian Mixture Models (GMM) for storm identification and image processing for storm tracking. The method has been successfully applied to Brazos County in Texas using the 2003 Multi-sensor Precipitation Estimator (MPE) NEXRAD rainfall data.

Spatial distribution of motor units recruited during electrical stimulation of the quadriceps muscle versus the femoral nerve.

PubMed

Rodriguez-Falces, Javier; Maffiuletti, Nicola A; Place, Nicolas

2013-11-01

In this study we investigated differences in the spatial recruitment of motor units (MUs) in the quadriceps when electrical stimulation is applied over the quadriceps belly versus the femoral nerve. M-waves and mechanical twitches were evoked using over-the-quadriceps and femoral nerve stimulation of gradually increasing intensity from 22 young, healthy subjects. Spatial recruitment was investigated using recruitment curves of M-waves recorded from the vastus medialis (VM) and vastus lateralis (VL) and of twitches recorded from the quadriceps. At maximal stimulation intensity (Imax), no differences were found between nerve and over-the-quadriceps stimulation. At submaximal intensities, VL M-wave amplitude was higher for over-the-quadriceps stimulation at 40% Imax, and peak twitch force was greater for nerve stimulation at 60% and 80% Imax. For the VM, MU spatial recruitment during nerve and over-the-quadriceps stimulation of increasing intensity occurred in a similar manner, whereas significant differences were observed for the VL. Copyright © 2013 Wiley Periodicals, Inc.

Revealing the Sub-Barrier Phase using a Spatiotemporal Interferometer with Orthogonal Two-Color Laser Fields of Comparable Intensity

NASA Astrophysics Data System (ADS)

Han, Meng; Ge, Peipei; Shao, Yun; Liu, Ming-Ming; Deng, Yongkai; Wu, Chengyin; Gong, Qihuang; Liu, Yunquan

2017-08-01

We measure photoelectron momentum distributions of Ar atoms in orthogonally polarized two-color laser fields with comparable intensities. The synthesized laser field is used to manipulate the oscillating tunneling barrier and the subsequent motion of electrons onto two spatial dimensions. The subcycle structures associated with the temporal double-slit interference are spatially separated and enhanced. We use such a spatiotemporal interferometer to reveal sub-barrier phase of strong-field tunneling ionization. This study shows that the tunneling process transfers the initial phase onto momentum distribution. Our work has the implication that the sub-barrier phase plays an indispensable role in photoelectron interference processes.

Magneto-optical visualization of three spatial components of inhomogeneous stray fields

NASA Astrophysics Data System (ADS)

Ivanov, V. E.

2012-08-01

The article deals with the physical principles of magneto-optical visualization (MO) of three spatial components of inhomogeneous stray fields with the help of FeCo metal indicator films in the longitudinal Kerr effect geometry. The inhomogeneous field is created by permanent magnets. Both p- and s-polarization light is used for obtaining MO images with their subsequent summing, subtracting and digitizing. As a result, the MO images and corresponding intensity coordinate dependences reflecting the distributions of the horizontal and vertical magnetization components in pure form have been obtained. Modeling of both the magnetization distribution in the indicator film and the corresponding MO images shows that corresponding to polar sensitivity the intensity is proportional to the normal field component, which permits normal field component mapping. Corresponding to longitudinal sensitivity, the intensity of the MO images reflects the angular distribution of the planar field component. MO images have singular points in which the planar component is zero and their movement under an externally homogeneous planar field permits obtaining of additional information on the two planar components of the field under study. The intensity distribution character in the vicinity of sources and sinks (singular points) remains the same under different orientations of the light incidence plane. The change of incident plane orientation by π/2 alters the distribution pattern in the vicinity of the saddle points.

Intra-pulse transition between ion acceleration mechanisms in intense laser-foil interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Padda, H.; King, M.; Gray, R. J.

Multiple ion acceleration mechanisms can occur when an ultrathin foil is irradiated with an intense laser pulse, with the dominant mechanism changing over the course of the interaction. Measurement of the spatial-intensity distribution of the beam of energetic protons is used to investigate the transition from radiation pressure acceleration to transparency-driven processes. It is shown numerically that radiation pressure drives an increased expansion of the target ions within the spatial extent of the laser focal spot, which induces a radial deflection of relatively low energy sheath-accelerated protons to form an annular distribution. Through variation of the target foil thickness, themore » opening angle of the ring is shown to be correlated to the point in time transparency occurs during the interaction and is maximized when it occurs at the peak of the laser intensity profile. Corresponding experimental measurements of the ring size variation with target thickness exhibit the same trends and provide insight into the intra-pulse laser-plasma evolution.« less

Inferring controls on the epidemiology of beech bark disease from spatial patterning of disease organisms

Treesearch

Jeffrey R. Garnas; David R. Houston; Mark J. Twery; Matthew P. Ayres; Celia Evans

2013-01-01

Spatial pattern in the distribution and abundance of organisms is an emergent property of collective rates of reproduction, survival and movement of individuals in a heterogeneous environment. The form, intensity and scale of spatial patterning can be used to test hypotheses regarding the relative importance of candidate processes to population dynamics. Using 84 plots...

Spatial Analysis of PAHs in Soils along an Urban-Suburban-Rural Gradient: scale effect, distribution patterns, diffusion and influencing factors

NASA Astrophysics Data System (ADS)

Peng, Chi; Wang, Meie; Chen, Weiping

2016-11-01

Spatial statistical methods including Cokriging interpolation, Morans I analysis, and geographically weighted regression (GWR) were used for studying the spatial characteristics of polycyclic aromatic hydrocarbon (PAH) accumulation in urban, suburban, and rural soils of Beijing. The concentrations of PAHs decreased spatially as the level of urbanization decreased. Generally, PAHs in soil showed two spatial patterns on the regional scale: (1) regional baseline depositions with a radius of 16.5 km related to the level of urbanization and (2) isolated pockets of soil contaminated with PAHs were found up to around 3.5 km from industrial point sources. In the urban areas, soil PAHs showed high spatial heterogeneity on the block scale, which was probably related to vegetation cover, land use, and physical soil disturbance. The distribution of total PAHs in urban blocks was unrelated to the indicators of the intensity of anthropogenic activity, namely population density, light intensity at night, and road density, but was significantly related to the same indicators in the suburban and rural areas. The moving averages of molecular ratios suggested that PAHs in the suburban and rural soils were a mix of local emissions and diffusion from urban areas.

Intensity-dependent atomic-phase effects in high-order harmonic generation

NASA Astrophysics Data System (ADS)

Peatross, J.; Meyerhofer, D. D.

1995-11-01

The far-field angular distributions of high-order harmonics of a 1054-nm laser, with orders ranging from the lower teens to the upper thirties, have been measured in thin, low-density Ar, Kr, and Xe targets. The 1.25-times-diffraction-limited, 1.4-ps-duration, Gaussian laser pulses were focused to intensities ranging from 3×1013 to 3×1014 W/cm2, using f/70 optics. A gas target localized the gas distribution near the laser focus to a thickness of about 1 mm at pressures as low as 0.3 Torr. The weak focusing geometry and the low gas pressures created experimental conditions for which the harmonics could be thought of as emerging from a plane at the laser focus rather than a three-dimensional volume. The far-field distributions of nearly all of the harmonics exhibit narrow central peaks surrounded by broad wings of about the same angular divergence as the emerging laser beam. The spatial wings are due to an intensity-dependent phase variation among the dipole moments of the individual target atoms. This phase variation gives rise to broad spatial interferences in the scattered light due to the radial and temporal variation of the laser intensity.

Analysis of security of optical encryption with spatially incoherent illumination technique

NASA Astrophysics Data System (ADS)

Cheremkhin, Pavel A.; Evtikhiev, Nikolay N.; Krasnov, Vitaly V.; Rodin, Vladislav G.; Shifrina, Anna V.

2017-03-01

Applications of optical methods for encryption purposes have been attracting interest of researchers for decades. The first and the most popular is double random phase encoding (DRPE) technique. There are many optical encryption techniques based on DRPE. Main advantage of DRPE based techniques is high security due to transformation of spectrum of image to be encrypted into white spectrum via use of first phase random mask which allows for encrypted images with white spectra. Downsides are necessity of using holographic registration scheme in order to register not only light intensity distribution but also its phase distribution, and speckle noise occurring due to coherent illumination. Elimination of these disadvantages is possible via usage of incoherent illumination instead of coherent one. In this case, phase registration no longer matters, which means that there is no need for holographic setup, and speckle noise is gone. This technique does not have drawbacks inherent to coherent methods, however, as only light intensity distribution is considered, mean value of image to be encrypted is always above zero which leads to intensive zero spatial frequency peak in image spectrum. Consequently, in case of spatially incoherent illumination, image spectrum, as well as encryption key spectrum, cannot be white. This might be used to crack encryption system. If encryption key is very sparse, encrypted image might contain parts or even whole unhidden original image. Therefore, in this paper analysis of security of optical encryption with spatially incoherent illumination depending on encryption key size and density is conducted.

Spatial distribution and implications to sources of halogenated flame retardants in riverine sediments of Taizhou, an intense e-waste recycling area in eastern China.

PubMed

Zhou, Shanshan; Fu, Jie; He, Huan; Fu, Jianjie; Tang, Qiaozhi; Dong, Minfeng; Pan, Yongqiang; Li, An; Liu, Weiping; Zhang, Limin

2017-10-01

Concentrations and spatial distribution pattern of organohalogen flame retardants were investigated in the riverine surface sediments from Taizhou, an intensive e-waste recycling region in China. The analytes were syn- and anti- Dechlorane Plus (DP), Dechloranes 602, 603, and 604, a DP monoadduct, two dechlorinated DPs and 8 congeners of polybrominated diphenyl ethers (PBDEs). The concentrations of Σ 8 PBDEs, ΣDP, ΣDec600s, and ΣDP-degradates ranged from <100 to 172,000, 100 to 55,000, not detectable (nd) to 1600, and nd to 2800 pg/g dry weight, respectively. BDE-209 and DP, both have been manufactured in China, had similar spatial distribution patterns in the study area, featured by distinctly recognizable hotspots some of which are in proximity to known e-waste dumping or metal recycling facilities. Such patterns were largely shared by Dec602 and dechlorinated DP, although their concentration levels were much lower. These major flame retardants significantly correlate with each other, and cluster together in the loading plot of principle component analysis. In contrast, most non-deca PBDE congeners do not correlate with DPs. Dec604 stood out having distinctly different spatial distribution pattern, which could be linked to historical use of mirex. Organic matter content of the sediment was not the dominant factor in determining the spatial pattern of pollution by halogenated flame retardants in the rivers of this study. Copyright © 2017 Elsevier Ltd. All rights reserved.

The spatial coherence function in scanning transmission electron microscopy and spectroscopy.

PubMed

Nguyen, D T; Findlay, S D; Etheridge, J

2014-11-01

We investigate the implications of the form of the spatial coherence function, also referred to as the effective source distribution, for quantitative analysis in scanning transmission electron microscopy, and in particular for interpreting the spatial origin of imaging and spectroscopy signals. These questions are explored using three different source distribution models applied to a GaAs crystal case study. The shape of the effective source distribution was found to have a strong influence not only on the scanning transmission electron microscopy (STEM) image contrast, but also on the distribution of the scattered electron wavefield and hence on the spatial origin of the detected electron intensities. The implications this has for measuring structure, composition and bonding at atomic resolution via annular dark field, X-ray and electron energy loss STEM imaging are discussed. Copyright © 2014 Elsevier B.V. All rights reserved.

Automated aberration compensation in high numerical aperture systems for arbitrary laser modes (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hering, Julian; Waller, Erik H.; von Freymann, Georg

2017-02-01

Since a large number of optical systems and devices are based on differently shaped focal intensity distributions (point-spread-functions, PSF), the PSF's quality is crucial for the application's performance. E.g., optical tweezers, optical potentials for trapping of ultracold atoms as well as stimulated-emission-depletion (STED) based microscopy and lithography rely on precisely controlled intensity distributions. However, especially in high numerical aperture (NA) systems, such complex laser modes are easily distorted by aberrations leading to performance losses. Although different approaches addressing phase retrieval algorithms have been recently presented[1-3], fast and automated aberration compensation for a broad variety of complex shaped PSFs in high NA systems is still missing. Here, we report on a Gerchberg-Saxton[4] based algorithm (GSA) for automated aberration correction of arbitrary PSFs, especially for high NA systems. Deviations between the desired target intensity distribution and the three-dimensionally (3D) scanned experimental focal intensity distribution are used to calculate a correction phase pattern. The target phase distribution plus the correction pattern are displayed on a phase-only spatial-light-modulator (SLM). Focused by a high NA objective, experimental 3D scans of several intensity distributions allow for characterization of the algorithms performance: aberrations are reliably identified and compensated within less than 10 iterations. References 1. B. M. Hanser, M. G. L. Gustafsson, D. A. Agard, and J. W. Sedat, "Phase-retrieved pupil functions in wide-field fluorescence microscopy," J. of Microscopy 216(1), 32-48 (2004). 2. A. Jesacher, A. Schwaighofer, S. Frhapter, C. Maurer, S. Bernet, and M. Ritsch-Marte, "Wavefront correction of spatial light modulators using an optical vortex image," Opt. Express 15(9), 5801-5808 (2007). 3. A. Jesacher and M. J. Booth, "Parallel direct laser writing in three dimensions with spatially dependent aberration correction," Opt. Express 18(20), 21090-21099 (2010). 4. R. W. Gerchberg and W. O. Saxton, "A practical algorithm for the determination of the phase from image and diffraction plane pictures," Optik 35(2), 237-246 (1972).

Numerical Study of the Role of Microphysical Latent Heating and Surface Heat Fluxes in a Severe Precipitation Event in the Warm Sector over Southern China

NASA Astrophysics Data System (ADS)

Yin, Jin-Fang; Wang, Dong-Hai; Liang, Zhao-Ming; Liu, Chong-Jian; Zhai, Guo-Qing; Wang, Hong

2018-02-01

Simulations of the severe precipitation event that occurred in the warm sector over southern China on 08 May 2014 are conducted using the Advanced Weather Research and Forecasting (WRF-ARWv3.5.1) model to investigate the roles of microphysical latent heating and surface heat fluxes during the severe precipitation processes. At first, observations from surface rain gauges and ground-based weather radars are used to evaluate the model outputs. Results show that the spatial distribution of 24-h accumulated precipitation is well reproduced, and the temporal and spatial distributions of the simulated radar reflectivity agree well with the observations. Then, several sensitive simulations are performed with the identical model configurations, except for different options in microphysical latent heating and surface heat fluxes. From the results, one of the significant findings is that the latent heating from warm rain microphysical processes heats the atmosphere in the initial phase of the precipitation and thus convective systems start by self-triggering and self-organizing, despite the fact that the environmental conditions are not favorable to the occurrence of precipitation event at the initial phase. In the case of the severe precipitation event over the warm sector, both warm and ice microphysical processes are active with the ice microphysics processes activated almost two hours later. According to the sensitive results, there is a very weak precipitation without heavy rainfall belt when microphysical latent heating is turned off. In terms of this precipitation event, the warm microphysics processes play significant roles on precipitation intensity, while the ice microphysics processes have effects on the spatial distribution of precipitation. Both surface sensible and latent heating have effects on the precipitation intensity and spatial distribution. By comparison, the surface sensible heating has a strong influence on the spatial distribution of precipitation, and the surface latent heating has only a slight impact on the precipitation intensity. The results indicate that microphysical latent heating might be an important factor for severe precipitation forecast in the warm sector over southern China. Surface sensible heating can have considerable influence on the precipitation spatial distribution and should not be neglected in the case of weak large-scale conditions with abundant water vapor in the warm sector.

Nonmydriatic fluorescence-based quantitative imaging of human macular pigment distributions

NASA Astrophysics Data System (ADS)

Sharifzadeh, Mohsen; Bernstein, Paul S.; Gellermann, Werner

2006-10-01

We have developed a CCD-camera-based nonmydriatic instrument that detects fluorescence from retinal lipofuscin chromophores ("autofluorescence") as a means to indirectly quantify and spatially image the distribution of macular pigment (MP). The lipofuscin fluorescence intensity is reduced at all retinal locations containing MP, since MP has a competing absorption in the blue-green wavelength region. Projecting a large diameter, 488 nm excitation spot onto the retina, centered on the fovea, but extending into the macular periphery, and comparing lipofuscin fluorescence intensities outside and inside the foveal area, it is possible to spatially map out the distribution of MP. Spectrally selective detection of the lipofuscin fluorescence reveals an important wavelength dependence of the obtainable image contrast and deduced MP optical density levels, showing that it is important to block out interfering fluorescence contributions in the detection setup originating from ocular media such as the lens. Measuring 70 healthy human volunteer subjects with no ocular pathologies, we find widely varying spatial extent of MP, distinctly differing distribution patterns of MP, and strongly differing absolute MP levels among individuals. Our population study suggests that MP imaging based on lipofuscin fluorescence is useful as a relatively simple, objective, and quantitative noninvasive optical technique suitable to rapidly screen MP levels and distributions in healthy humans with undilated pupils.

Nonlinear Reduced-Order Analysis with Time-Varying Spatial Loading Distributions

NASA Technical Reports Server (NTRS)

Prezekop, Adam

2008-01-01

Oscillating shocks acting in combination with high-intensity acoustic loadings present a challenge to the design of resilient hypersonic flight vehicle structures. This paper addresses some features of this loading condition and certain aspects of a nonlinear reduced-order analysis with emphasis on system identification leading to formation of a robust modal basis. The nonlinear dynamic response of a composite structure subject to the simultaneous action of locally strong oscillating pressure gradients and high-intensity acoustic loadings is considered. The reduced-order analysis used in this work has been previously demonstrated to be both computationally efficient and accurate for time-invariant spatial loading distributions, provided that an appropriate modal basis is used. The challenge of the present study is to identify a suitable basis for loadings with time-varying spatial distributions. Using a proper orthogonal decomposition and modal expansion, it is shown that such a basis can be developed. The basis is made more robust by incrementally expanding it to account for changes in the location, frequency and span of the oscillating pressure gradient.

Experimental observation of spatially resolved photo-luminescence intensity distribution in dual mode upconverting nanorod bundles

PubMed Central

Kumar, Pawan; Singh, Satbir; Singh, V. N.; Singh, Nidhi; Gupta, R. K.; Gupta, Bipin Kumar

2017-01-01

A novel method for demonstration of photoluminescence intensity distribution in upconverting nanorod bundles using confocal microscopy is reported. Herein, a strategy for the synthesis of highly luminescent dual mode upconverting/downshift Y1.94O3:Ho3+0.02/Yb3+0.04 nanorod bundles by a facile hydrothermal route has been introduced. These luminescent nanorod bundles exhibit strong green emission at 549 nm upon excitations at 449 nm and 980 nm with quantum efficiencies of ~6.3% and ~1.1%, respectively. The TEM/HRTEM results confirm that these bundles are composed of several individual nanorods with diameter of ~100 nm and length in the range of 1–3 μm. Furthermore, two dimensional spatially resolved photoluminescence intensity distribution study has been carried out using confocal photoluminescence microscope throughout the nanorod bundles. This study provides a new direction for the potential use of such emerging dual mode nanorod bundles as photon sources for next generation flat panel optical display devices, bio-medical applications, luminescent security ink and enhanced energy harvesting in photovoltaic applications. PMID:28211891

High-latitude distributions of plasma waves and spatial irregularities from DE 2 alternating current electric field observations

NASA Technical Reports Server (NTRS)

Heppner, J. P.; Liebrecht, M. C.; Maynard, N. C.; Pfaff, R. F.

1993-01-01

The high-latitude spatial distributions of average signal intensities in 12 frequency channels between 4 Hz and 512 kHz as measured by the ac electric field spectrometers on the DE-2 spacecraft are analyzed for 18 mo of measurements. In MLT-INL (magnetic local time-invariant latitude) there are three distinct distributions that can be identified with 4-512 Hz signals from spatial irregularities and Alfven waves, 256-Hz to 4.1-kHz signals from ELF hiss, and 4.1-64 kHz signals from VLF auroral hiss, respectively. Overlap between ELF hiss and spatial irregularity signals occurs in the 256-512 Hz band. VLF hiss signals extend downward in frequency into the 1.0-4.1 kHz band and upward into the frequency range 128-512 kHz. The distinctly different spatial distribution patterns for the three bands, 4-256 Hz, 512-1204 Hz, and 4.1-64 kHz, indicate a lack of any causal relationships between VLF hiss, ELF hiss, and lower-frequency signals from spatial irregularities and Alfven waves.

Phonon transport in a curved aluminum thin film due to laser short pulse irradiation

NASA Astrophysics Data System (ADS)

Mansoor, Saad Bin; Yilbas, Bekir Sami

2018-05-01

Laser short-pulse heating of a curved aluminum thin film is investigated. The Boltzmann transport equation is incorporated to formulate the heating situation. A Gaussian laser intensity distribution is considered along the film arc and time exponentially decaying of pulse intensity is incorporated in the analysis. The governing equations of energy transport in the electron and lattice sub-systems are coupled through the electron-phonon coupling parameter. To quantify the phonon intensity distribution in the thin film, equivalent equilibrium temperature is introduced, which is associated with the average energy of all phonons around a local point when the phonon energies are redistributed adiabatically to an equilibrium state. It is found the numerical simulations that electron temperature follows similar trend to the spatial distribution of the laser pulse intensity at the film edge. Temporal variation of electron temperature does not follow the laser pulse intensity distribution. The rise of temperature in the electron sub-system is fast while it remains slow in the lattice sub-system.

Raccoon spatial requirements and multi-scale habitat selection within an intensively managed central Appalachian forest

USGS Publications Warehouse

Owen, Sheldon F.; Berl, Jacob L.; Edwards, John W.; Ford, W. Mark; Wood, Petra Bohall

2015-01-01

We studied a raccoon (Procyon lotor) population within a managed central Appalachian hardwood forest in West Virginia to investigate the effects of intensive forest management on raccoon spatial requirements and habitat selection. Raccoon home-range (95% utilization distribution) and core-area (50% utilization distribution) size differed between sexes with males maintaining larger (2×) home ranges and core areas than females. Home-range and core-area size did not differ between seasons for either sex. We used compositional analysis to quantify raccoon selection of six different habitat types at multiple spatial scales. Raccoons selected riparian corridors (riparian management zones [RMZ]) and intact forests (> 70 y old) at the core-area spatial scale. RMZs likely were used by raccoons because they provided abundant denning resources (i.e., large-diameter trees) as well as access to water. Habitat composition associated with raccoon foraging locations indicated selection for intact forests, riparian areas, and regenerating harvest (stands <10 y old). Although raccoons were able to utilize multiple habitat types for foraging resources, a selection of intact forest and RMZs at multiple spatial scales indicates the need of mature forest (with large-diameter trees) for this species in managed forests in the central Appalachians.

Fine-scale spatial distribution of the common lugworm Arenicola marina, and effects of intertidal clam fishing

NASA Astrophysics Data System (ADS)

Boldina, Inna; Beninger, Peter G.

2014-04-01

Despite its ubiquity and its role as an ecosystem engineer on temperate intertidal mudflats, little is known of the spatial ecology of the lugworm Arenicola marina. We estimated lugworm densities and analyzed the spatial distribution of A. marina on a French Atlantic mudflat subjected to long-term clam digging activities, and compared these to a nearby pristine reference mudflat, using a combination of geostatistical techniques: point-pattern analysis, autocorrelation, and wavelet analysis. Lugworm densities were an order of magnitude greater at the reference site. Although A. marina showed an aggregative spatial distribution at both sites, the characteristics and intensity of aggregation differed markedly between sites. The reference site showed an inhibition process (regular distribution) at distances <7.5 cm, whereas the impacted site showed a random distribution at this scale. At distances from 15 cm to several tens of meters, the spatial distribution of A. marina was clearly aggregated at both sites; however, the autocorrelation strength was much weaker at the impacted site. In addition, the non-impacted site presented multi-scale spatial distribution, which was not evident at the impacted site. The differences observed between the spatial distributions of the fishing-impacted vs. the non-impacted site reflect similar findings for other components of these two mudflat ecosystems, suggesting common community-level responses to prolonged mechanical perturbation: a decrease in naturally-occurring aggregation. This change may have consequences for basic biological characteristics such as reproduction, recruitment, growth, and feeding.

Geostatistical Evaluation of Natural Tree Regeneration of a Disturbed Forest

Treesearch

José Germán Flores Garnica; David Arturo Moreno Gonzalez; Juan de Dios Benavides Solorio

2006-01-01

The implementation of silvicultural strategies in a forest management has to guaranty forest sustainability, which is supported by an adequate regeneration. Therefore, quality and intensity of silvicultural practices is based on an accurate knowledge of the current spatial distribution of regeneration. At the same time, this regeneration is determined by the spatial...

3D radiation belt diffusion model results using new empirical models of whistler chorus and hiss

NASA Astrophysics Data System (ADS)

Cunningham, G.; Chen, Y.; Henderson, M. G.; Reeves, G. D.; Tu, W.

2012-12-01

3D diffusion codes model the energization, radial transport, and pitch angle scattering due to wave-particle interactions. Diffusion codes are powerful but are limited by the lack of knowledge of the spatial & temporal distribution of waves that drive the interactions for a specific event. We present results from the 3D DREAM model using diffusion coefficients driven by new, activity-dependent, statistical models of chorus and hiss waves. Most 3D codes parameterize the diffusion coefficients or wave amplitudes as functions of magnetic activity indices like Kp, AE, or Dst. These functional representations produce the average value of the wave intensities for a given level of magnetic activity; however, the variability of the wave population at a given activity level is lost with such a representation. Our 3D code makes use of the full sample distributions contained in a set of empirical wave databases (one database for each wave type, including plasmaspheric hiss, lower and upper hand chorus) that were recently produced by our team using CRRES and THEMIS observations. The wave databases store the full probability distribution of observed wave intensity binned by AE, MLT, MLAT and L*. In this presentation, we show results that make use of the wave intensity sample probability distributions for lower-band and upper-band chorus by sampling the distributions stochastically during a representative CRRES-era storm. The sampling of the wave intensity probability distributions produces a collection of possible evolutions of the phase space density, which quantifies the uncertainty in the model predictions caused by the uncertainty of the chorus wave amplitudes for a specific event. A significant issue is the determination of an appropriate model for the spatio-temporal correlations of the wave intensities, since the diffusion coefficients are computed as spatio-temporal averages of the waves over MLT, MLAT and L*. The spatiotemporal correlations cannot be inferred from the wave databases. In this study we use a temporal correlation of ~1 hour for the sampled wave intensities that is informed by the observed autocorrelation in the AE index, a spatial correlation length of ~100 km in the two directions perpendicular to the magnetic field, and a spatial correlation length of 5000 km in the direction parallel to the magnetic field, according to the work of Santolik et al (2003), who used multi-spacecraft measurements from Cluster to quantify the correlation length scales for equatorial chorus . We find that, despite the small correlation length scale for chorus, there remains significant variability in the model outcomes driven by variability in the chorus wave intensities.

Regular and Chaotic Spatial Distribution of Bose-Einstein Condensed Atoms in a Ratchet Potential

NASA Astrophysics Data System (ADS)

Li, Fei; Xu, Lan; Li, Wenwu

2018-02-01

We study the regular and chaotic spatial distribution of Bose-Einstein condensed atoms with a space-dependent nonlinear interaction in a ratchet potential. There exists in the system a space-dependent atomic current that can be tuned via Feshbach resonance technique. In the presence of the space-dependent atomic current and a weak ratchet potential, the Smale-horseshoe chaos is studied and the Melnikov chaotic criterion is obtained. Numerical simulations show that the ratio between the intensities of optical potentials forming the ratchet potential, the wave vector of the laser producing the ratchet potential or the wave vector of the modulating laser can be chosen as the controlling parameters to result in or avoid chaotic spatial distributional states.

Study on Urban Heat Island Intensity Level Identification Based on an Improved Restricted Boltzmann Machine.

PubMed

Zhang, Yang; Jiang, Ping; Zhang, Hongyan; Cheng, Peng

2018-01-23

Thermal infrared remote sensing has become one of the main technology methods used for urban heat island research. When applying urban land surface temperature inversion of the thermal infrared band, problems with intensity level division arise because the method is subjective. However, this method is one of the few that performs heat island intensity level identification. This paper will build an intensity level identifier for an urban heat island, by using weak supervision and thought-based learning in an improved, restricted Boltzmann machine (RBM) model. The identifier automatically initializes the annotation and optimizes the model parameters sequentially until the target identifier is completed. The algorithm needs very little information about the weak labeling of the target training sample and generates an urban heat island intensity spatial distribution map. This study can provide reliable decision-making support for urban ecological planning and effective protection of urban ecological security. The experimental results showed the following: (1) The heat island effect in Wuhan is existent and intense. Heat island areas are widely distributed. The largest heat island area is in Wuhan, followed by the sub-green island. The total area encompassed by heat island and strong island levels accounts for 54.16% of the land in Wuhan. (2) Partially based on improved RBM identification, this method meets the research demands of determining the spatial distribution characteristics of the internal heat island effect; its identification accuracy is superior to that of comparable methods.

Study on Urban Heat Island Intensity Level Identification Based on an Improved Restricted Boltzmann Machine

PubMed Central

Jiang, Ping; Zhang, Hongyan; Cheng, Peng

2018-01-01

Thermal infrared remote sensing has become one of the main technology methods used for urban heat island research. When applying urban land surface temperature inversion of the thermal infrared band, problems with intensity level division arise because the method is subjective. However, this method is one of the few that performs heat island intensity level identification. This paper will build an intensity level identifier for an urban heat island, by using weak supervision and thought-based learning in an improved, restricted Boltzmann machine (RBM) model. The identifier automatically initializes the annotation and optimizes the model parameters sequentially until the target identifier is completed. The algorithm needs very little information about the weak labeling of the target training sample and generates an urban heat island intensity spatial distribution map. This study can provide reliable decision-making support for urban ecological planning and effective protection of urban ecological security. The experimental results showed the following: (1) The heat island effect in Wuhan is existent and intense. Heat island areas are widely distributed. The largest heat island area is in Wuhan, followed by the sub-green island. The total area encompassed by heat island and strong island levels accounts for 54.16% of the land in Wuhan. (2) Partially based on improved RBM identification, this method meets the research demands of determining the spatial distribution characteristics of the internal heat island effect; its identification accuracy is superior to that of comparable methods. PMID:29360786

Estimating the spatial distribution of field-applied mushroom compost in the Brandywine-Christina River Basin using multispectral remote sensing

NASA Astrophysics Data System (ADS)

Moxey, Kelsey A.

The world's greatest concentration of mushroom farms is settled within the Brandywine-Christina River Basin in Chester County in southeastern Pennsylvania. This industry produces a nutrient-rich byproduct known as spent mushroom compost, which has been traditionally applied to local farm fields as an organic fertilizer and soil amendment. While mushroom compost has beneficial properties, the possible over-application to farm fields could potentially degrade stream water quality. The goal of this study was to estimate the spatial extent and intensity of field-applied mushroom compost. We applied a remote sensing approach using Landsat multispectral imagery. We utilized the soil line technique, using the red and near-infrared bands, to estimate differences in soil wetness as a result of increased soil organic matter content from mushroom compost. We validated soil wetness estimates by examining the spectral response of references sites. We performed a second independent validation analysis using expert knowledge from agricultural extension agents. Our results showed that the soil line based wetness index worked well. The spectral validation illustrated that compost changes the spectral response of soil because of changes in wetness. The independent expert validation analysis produced a strong significant correlation between our remotely-sensed wetness estimates and the empirical ratings of compost application intensities. Overall, the methodology produced realistic spatial distributions of field-applied compost application intensities across the study area. These spatial distributions will be used for follow-up studies to assess the effect of spent mushroom compost on stream water quality.

Spatial distribution, sampling precision and survey design optimisation with non-normal variables: The case of anchovy (Engraulis encrasicolus) recruitment in Spanish Mediterranean waters

NASA Astrophysics Data System (ADS)

Tugores, M. Pilar; Iglesias, Magdalena; Oñate, Dolores; Miquel, Joan

2016-02-01

In the Mediterranean Sea, the European anchovy (Engraulis encrasicolus) displays a key role in ecological and economical terms. Ensuring stock sustainability requires the provision of crucial information, such as species spatial distribution or unbiased abundance and precision estimates, so that management strategies can be defined (e.g. fishing quotas, temporal closure areas or marine protected areas MPA). Furthermore, the estimation of the precision of global abundance at different sampling intensities can be used for survey design optimisation. Geostatistics provide a priori unbiased estimations of the spatial structure, global abundance and precision for autocorrelated data. However, their application to non-Gaussian data introduces difficulties in the analysis in conjunction with low robustness or unbiasedness. The present study applied intrinsic geostatistics in two dimensions in order to (i) analyse the spatial distribution of anchovy in Spanish Western Mediterranean waters during the species' recruitment season, (ii) produce distribution maps, (iii) estimate global abundance and its precision, (iv) analyse the effect of changing the sampling intensity on the precision of global abundance estimates and, (v) evaluate the effects of several methodological options on the robustness of all the analysed parameters. The results suggested that while the spatial structure was usually non-robust to the tested methodological options when working with the original dataset, it became more robust for the transformed datasets (especially for the log-backtransformed dataset). The global abundance was always highly robust and the global precision was highly or moderately robust to most of the methodological options, except for data transformation.

Intensity distribution of the x ray source for the AXAF VETA-I mirror test

NASA Technical Reports Server (NTRS)

Zhao, Ping; Kellogg, Edwin M.; Schwartz, Daniel A.; Shao, Yibo; Fulton, M. Ann

1992-01-01

The X-ray generator for the AXAF VETA-I mirror test is an electron impact X-ray source with various anode materials. The source sizes of different anodes and their intensity distributions were measured with a pinhole camera before the VETA-I test. The pinhole camera consists of a 30 micrometers diameter pinhole for imaging the source and a Microchannel Plate Imaging Detector with 25 micrometers FWHM spatial resolution for detecting and recording the image. The camera has a magnification factor of 8.79, which enables measuring the detailed spatial structure of the source. The spot size, the intensity distribution, and the flux level of each source were measured with different operating parameters. During the VETA-I test, microscope pictures were taken for each used anode immediately after it was brought out of the source chamber. The source sizes and the intensity distribution structures are clearly shown in the pictures. They are compared and agree with the results from the pinhole camera measurements. This paper presents the results of the above measurements. The results show that under operating conditions characteristic of the VETA-I test, all the source sizes have a FWHM of less than 0.45 mm. For a source of this size at 528 meters away, the angular size to VETA is less than 0.17 arcsec which is small compared to the on ground VETA angular resolution (0.5 arcsec, required and 0.22 arcsec, measured). Even so, the results show the intensity distributions of the sources have complicated structures. These results were crucial for the VETA data analysis and for obtaining the on ground and predicted in orbit VETA Point Response Function.

Small-angle x-ray scattering in amorphous silicon: A computational study

NASA Astrophysics Data System (ADS)

Paudel, Durga; Atta-Fynn, Raymond; Drabold, David A.; Elliott, Stephen R.; Biswas, Parthapratim

2018-05-01

We present a computational study of small-angle x-ray scattering (SAXS) in amorphous silicon (a -Si) with particular emphasis on the morphology and microstructure of voids. The relationship between the scattering intensity in SAXS and the three-dimensional structure of nanoscale inhomogeneities or voids is addressed by generating large high-quality a -Si networks with 0.1%-0.3% volume concentration of voids, as observed in experiments using SAXS and positron annihilation spectroscopy. A systematic study of the variation of the scattering intensity in the small-angle scattering region with the size, shape, number density, and the spatial distribution of the voids in the networks is presented. Our results suggest that the scattering intensity in the small-angle region is particularly sensitive to the size and the total volume fraction of the voids, but the effect of the geometry or shape of the voids is less pronounced in the intensity profiles. A comparison of the average size of the voids obtained from the simulated values of the intensity, using the Guinier approximation and Kratky plots, with that of the same from the spatial distribution of the atoms in the vicinity of void surfaces is presented.

Simulation study on electric field intensity above train roof

NASA Astrophysics Data System (ADS)

Fan, Yizhe; Li, Huawei; Yang, Shasha

2018-04-01

In order to understand the distribution of electric field in the space above the train roof accurately and select the installation position of the detection device reasonably, in this paper, the 3D model of pantograph-catenary is established by using SolidWorks software, and the spatial electric field distribution of pantograph-catenary model is simulated based on Comsol software. According to the electric field intensity analysis within the 0.4m space above train roof, we give a reasonable installation of the detection device.

Using kernel density estimates to investigate lymphatic filariasis in northeast Brazil

PubMed Central

Medeiros, Zulma; Bonfim, Cristine; Brandão, Eduardo; Netto, Maria José Evangelista; Vasconcellos, Lucia; Ribeiro, Liany; Portugal, José Luiz

2012-01-01

After more than 10 years of the Global Program to Eliminate Lymphatic Filariasis (GPELF) in Brazil, advances have been seen, but the endemic disease persists as a public health problem. The aim of this study was to describe the spatial distribution of lymphatic filariasis in the municipality of Jaboatão dos Guararapes, Pernambuco, Brazil. An epidemiological survey was conducted in the municipality, and positive filariasis cases identified in this survey were georeferenced in point form, using the GPS. A kernel intensity estimator was applied to identify clusters with greater intensity of cases. We examined 23 673 individuals and 323 individuals with microfilaremia were identified, representing a mean prevalence rate of 1.4%. Around 88% of the districts surveyed presented cases of filarial infection, with prevalences of 0–5.6%. The male population was more affected by the infection, with 63.8% of the cases (P<0.005). Positive cases were found in all age groups examined. The kernel intensity estimator identified the areas of greatest intensity and least intensity of filarial infection cases. The case distribution was heterogeneous across the municipality. The kernel estimator identified spatial clusters of cases, thus indicating locations with greater intensity of transmission. The main advantage of this type of analysis lies in its ability to rapidly and easily show areas with the highest concentration of cases, thereby contributing towards planning, monitoring, and surveillance of filariasis elimination actions. Incorporation of geoprocessing and spatial analysis techniques constitutes an important tool for use within the GPELF. PMID:22943547

Time-dependent spatial intensity profiles of near-infrared idler pulses from nanosecond optical parametric oscillators

NASA Astrophysics Data System (ADS)

Olafsen, L. J.; Olafsen, J. S.; Eaves, I. K.

2018-06-01

We report on an experimental investigation of the time-dependent spatial intensity distribution of near-infrared idler pulses from an optical parametric oscillator measured using an infrared (IR) camera, in contrast to beam profiles obtained using traditional knife-edge techniques. Comparisons show the information gained by utilizing the thermal camera provides more detail than the spatially- or time-averaged measurements from a knife-edge profile. Synchronization, averaging, and thresholding techniques are applied to enhance the images acquired. The additional information obtained can improve the process by which semiconductor devices and other IR lasers are characterized for their beam quality and output response and thereby result in IR devices with higher performance.

Single-beam, dark toroidal optical traps for cold atoms

NASA Astrophysics Data System (ADS)

Fatemi, Fredrik K.; Olson, Spencer E.; Bashkansky, Mark; Dutton, Zachary; Terraciano, Matthew

2007-02-01

We demonstrate the generation of single-beam dark toroidal optical intensity distributions, which are of interest for neutral atom storage and atom interferometry. We demonstrate experimentally and numerically optical potentials that contain a ring-shaped intensity minimum, bounded in all directions by higher intensity. We use a spatial light modulator to alter the phase of an incident laser beam, and analyze the resulting optical propagation characteristics. For small toroidal traps (< 50 μm diameter), we find an optimal superposition of Laguerre-Gaussian modes that allows the formation of single-beam toroidal traps. We generate larger toroidal bottle traps by focusing hollow beams with toroidal lenses imprinted onto the spatial light modulator.

Spatial and temporal assessment of cumulative disturbance impacts due to military training, burning, haying, and their interactions on land condition of Fort Riley.

PubMed

Wang, Guangxing; Murphy, Dana; Oller, Adam; Howard, Heidi R; Anderson, Alan B; Rijal, Santosh; Myers, Natalie R; Woodford, Philip

2014-07-01

The effects of military training activities on the land condition of Army installations vary spatially and temporally. Training activities observably degrade land condition while also increasing biodiversity and stabilizing ecosystems. Moreover, other anthropogenic activities regularly occur on military lands such as prescribed burns and agricultural haying-adding to the dynamics of land condition. Thus, spatially and temporally assessing the impacts of military training, prescribed burning, agricultural haying, and their interactions is critical to the management of military lands. In this study, the spatial distributions and patterns of military training-induced disturbance frequency were derived using plot observation and point observation-based method, at Fort Riley, Kansas from 1989 to 2001. Moreover, spatial and variance analysis of cumulative impacts due to military training, burning, haying, and their interactions on the land condition of Fort Riley were conducted. The results showed that: (1) low disturbance intensity dominated the majority of the study area with exception of concentrated training within centralized areas; (2) high and low values of disturbance frequency were spatially clustered and had spatial patterns that differed significantly from a random distribution; and (3) interactions between prescribed burning and agricultural haying were not significant in terms of either soil erosion or disturbance intensity although their means and variances differed significantly between the burned and non-burned areas and between the hayed and non-hayed areas.

[Spatial point patterns of Antarctic krill fishery in the northern Antarctic Peninsula].

PubMed

Yang, Xiao Ming; Li, Yi Xin; Zhu, Guo Ping

2016-12-01

As a key species in the Antarctic ecosystem, the spatial distribution of Antarctic krill (thereafter krill) often tends to present aggregation characteristics, which therefore reflects the spatial patterns of krill fishing operation. Based on the fishing data collected from Chinese krill fishing vessels, of which vessel A was professional krill fishing vessel and Vessel B was a fishing vessel which shifted between Chilean jack mackerel (Trachurus murphyi) fishing ground and krill fishing ground. In order to explore the characteristics of spatial distribution pattern and their ecological effects of two obvious different fishing fleets under a high and low nominal catch per unit effort (CPUE), from the viewpoint of spatial point pattern, the present study analyzed the spatial distribution characteristics of krill fishery in the northern Antarctic Peninsula from three aspects: (1) the two vessels' point pattern characteristics of higher CPUEs and lower CPUEs at different scales; (2) correlation of the bivariate point patterns between these points of higher CPUE and lower CPUE; and (3) correlation patterns of CPUE. Under the analysis derived from the Ripley's L function and mark correlation function, the results showed that the point patterns of the higher/lo-wer catch available were similar, both showing an aggregation distribution in this study windows at all scale levels. The aggregation intensity of krill fishing was nearly maximum at 15 km spatial scale, and kept stably higher values at the scale of 15-50 km. The aggregation intensity of krill fishery point patterns could be described in order as higher CPUE of vessel A > lower CPUE of vessel B >higher CPUE of vessel B > higher CPUE of vessel B. The relationship of the higher and lo-wer CPUEs of vessel A showed positive correlation at the spatial scale of 0-75 km, and presented stochastic relationship after 75 km scale, whereas vessel B showed positive correlation at all spatial scales. The point events of higher and lower CPUEs were synchronized, showing significant correlations at most of spatial scales because of the dynamics nature and complex of krill aggregation patterns. The distribution of vessel A's CPUEs was positively correlated at scales of 0-44 km, but negatively correlated at the scales of 44-80 km. The distribution of vessel B's CPUEs was negatively correlated at the scales of 50-70 km, but no significant correlations were found at other scales. The CPUE mark point patterns showed a negative correlation, which indicated that intraspecific competition for space and prey was significant. There were significant differences in spatial point pattern distribution between vessel A with higher fishing capacity and vessel B with lower fishing capacity. The results showed that the professional krill fishing vessel is suitable to conduct the analysis of spatial point pattern and scientific fishery survey.

Map of distribution of six forest ownership types in the conterminous United States

Treesearch

Jaketon H. Hewes; Brett J. Butler; Greg C. Liknes; Mark D. Nelson; Stephanie A. Snyder

2014-01-01

This map depicts the spatial distribution of ownership types across forest land in the conterminous United States circa 2009. The distribution is derived, in part, from Forest Inventory and Analysis (FIA) data that are collected at a sample intensity of approximately one plot per 2400 ha across the United States (U.S. Forest Service 2012). Ownership categories were...

Exploration of Urban Spatial Planning Evaluation Based on Humanland Harmony

NASA Astrophysics Data System (ADS)

Hu, X. S.; Ma, Q. R.; Liang, W. Q.; Wang, C. X.; Xiong, X. Q.; Han, X. H.

2017-09-01

This study puts forward a new concept, "population urbanization level forecast - driving factor analysis - urban spatial planning analysis" for achieving efficient and intensive development of urbanization considering human-land harmony. We analyzed big data for national economic and social development, studied the development trends of population urbanization and its influencing factors using the grey system model in Chengmai county of Hainan province, China. In turn, we calculated the population of Chengmai coming years based on the forecasting urbanization rate and the corresponding amount of urban construction land, and evaluated the urban spatial planning with GIS spatial analysis method in the study area. The result shows that the proposed concept is feasible for evaluation of urban spatial planning, and is meaningful for guiding the rational distribution of urban space, controlling the scale of development, improving the quality of urbanization and thus promoting highly-efficient and intensive use of limited land resource.

Spatial Distribution of Resonance in the Velocity Field for Transonic Flow over a Rectangular Cavity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beresh, Steven J.; Wagner, Justin L.; Casper, Katya M.

Pulse-burst particle image velocimetry (PIV) has been used to acquire time-resolved data at 37.5 kHz of the flow over a finite-width rectangular cavity at Mach 0.8. Power spectra of the PIV data reveal four resonance modes that match the frequencies detected simultaneously using high-frequency wall pressure sensors but whose magnitudes exhibit spatial dependence throughout the cavity. Spatio-temporal cross-correlations of velocity to pressure were calculated after bandpass filtering for specific resonance frequencies. Cross-correlation magnitudes express the distribution of resonance energy, revealing local maxima and minima at the edges of the shear layer attributable to wave interference between downstream- and upstream-propagating disturbances.more » Turbulence intensities were calculated using a triple decomposition and are greatest in the core of the shear layer for higher modes, where resonant energies ordinarily are lower. Most of the energy for the lowest mode lies in the recirculation region and results principally from turbulence rather than resonance. Together, the velocity-pressure cross-correlations and the triple-decomposition turbulence intensities explain the sources of energy identified in the spatial distributions of power spectra amplitudes.« less

Spatial Distribution of Resonance in the Velocity Field for Transonic Flow over a Rectangular Cavity

DOE PAGES

Beresh, Steven J.; Wagner, Justin L.; Casper, Katya M.; ...

2017-07-27

Pulse-burst particle image velocimetry (PIV) has been used to acquire time-resolved data at 37.5 kHz of the flow over a finite-width rectangular cavity at Mach 0.8. Power spectra of the PIV data reveal four resonance modes that match the frequencies detected simultaneously using high-frequency wall pressure sensors but whose magnitudes exhibit spatial dependence throughout the cavity. Spatio-temporal cross-correlations of velocity to pressure were calculated after bandpass filtering for specific resonance frequencies. Cross-correlation magnitudes express the distribution of resonance energy, revealing local maxima and minima at the edges of the shear layer attributable to wave interference between downstream- and upstream-propagating disturbances.more » Turbulence intensities were calculated using a triple decomposition and are greatest in the core of the shear layer for higher modes, where resonant energies ordinarily are lower. Most of the energy for the lowest mode lies in the recirculation region and results principally from turbulence rather than resonance. Together, the velocity-pressure cross-correlations and the triple-decomposition turbulence intensities explain the sources of energy identified in the spatial distributions of power spectra amplitudes.« less

Spatial variability of "Did You Feel It?" intensity data: insights into sampling biases in historical earthquake intensity distributions

USGS Publications Warehouse

Hough, Susan E.

2013-01-01

Recent parallel development of improved quantitative methods to analyze intensity distributions for historical earthquakes and of web‐based systems for collecting intensity data for modern earthquakes provides an opportunity to reconsider not only important individual historical earthquakes but also the overall characterization of intensity distributions for historical events. The focus of this study is a comparison between intensity distributions of historical earthquakes with those from modern earthquakes for which intensities have been determined by the U.S. Geological Survey “Did You Feel It?” (DYFI) website (see Data and Resources). As an example of a historical earthquake, I focus initially on the 1843 Marked Tree, Arkansas, event. Its magnitude has been previously estimated as 6.0–6.2. I first reevaluate the macroseismic effects of this earthquake, assigning intensities using a traditional approach, and estimate a preferred magnitude of 5.4. Modified Mercalli intensity (MMI) values for the Marked Tree earthquake are higher, on average, than those from the 2011 >Mw 5.8 Mineral, Virginia, earthquake for distances ≤500  km but comparable or lower on average at larger distances, with a smaller overall felt extent. Intensity distributions for other moderate historical earthquakes reveal similar discrepancies; the discrepancy is also even more pronounced using earlier published intensities for the 1843 earthquake. I discuss several hypotheses to explain the discrepancies, including the possibility that intensity values associated with historical earthquakes are commonly inflated due to reporting/sampling biases. A detailed consideration of the DYFI intensity distribution for the Mineral earthquake illustrates how reporting and sampling biases can account for historical earthquake intensity biases as high as two intensity units and for the qualitative difference in intensity distance decays for modern versus historical events. Thus, intensity maps for historical earthquakes tend to imply more widespread damage patterns than are revealed by intensity distributions of modern earthquakes of comparable magnitude. However, intensity accounts of historical earthquakes often include fragmentary accounts suggesting long‐period shaking effects that will likely not be captured fully in historical intensity distributions.

Dynamic Analysis of Soil Erosion in Songhua River Watershed

NASA Astrophysics Data System (ADS)

Zhang, Yujuan; Li, Xiuhai; Wang, Qiang; Liu, Jiang; Liang, Xin; Li, Dan; Ni, Chundi; Liu, Yan

2018-01-01

In this paper, based on RS and GIS technology and Revised Universal Soil Loss Equation (RUSLE), the soil erosion dynamic changes during the two periods of 1990 and 2010 in Bin County was analyzed by using the Landsat TM data of the two periods, so as to reveal the soil erosion spatial distribution pattern and spatial and temporal dynamic evolution rule in the region. The results showed that: the overall patterns of soil erosion were basically the same in both periods, mainly featuring slight erosion and mild erosion, with the area proportions of 80.68% and 74.71% respectively. The slight and extremely intensive erosion changing rates showed a narrowing trend; mild, moderate and intensive erosion was increasing, with a trend of increased soil erosion; mild and intensive erosion were developing towards moderate erosion and moderate and extremely intensive erosion were progressing towards intensive erosion.

Statistics of Optical Coherence Tomography Data From Human Retina

PubMed Central

de Juan, Joaquín; Ferrone, Claudia; Giannini, Daniela; Huang, David; Koch, Giorgio; Russo, Valentina; Tan, Ou; Bruni, Carlo

2010-01-01

Optical coherence tomography (OCT) has recently become one of the primary methods for noninvasive probing of the human retina. The pseudoimage formed by OCT (the so-called B-scan) varies probabilistically across pixels due to complexities in the measurement technique. Hence, sensitive automatic procedures of diagnosis using OCT may exploit statistical analysis of the spatial distribution of reflectance. In this paper, we perform a statistical study of retinal OCT data. We find that the stretched exponential probability density function can model well the distribution of intensities in OCT pseudoimages. Moreover, we show a small, but significant correlation between neighbor pixels when measuring OCT intensities with pixels of about 5 µm. We then develop a simple joint probability model for the OCT data consistent with known retinal features. This model fits well the stretched exponential distribution of intensities and their spatial correlation. In normal retinas, fit parameters of this model are relatively constant along retinal layers, but varies across layers. However, in retinas with diabetic retinopathy, large spikes of parameter modulation interrupt the constancy within layers, exactly where pathologies are visible. We argue that these results give hope for improvement in statistical pathology-detection methods even when the disease is in its early stages. PMID:20304733

Dispersal leads to spatial autocorrelation in species distributions: A simulation model

USGS Publications Warehouse

Bahn, V.; Krohn, W.B.; O'Connor, R.J.

2008-01-01

Compared to population growth regulated by local conditions, dispersal has been underappreciated as a central process shaping the spatial distribution of populations. This paper asks: (a) which conditions increase the importance of dispersers relative to local recruits in determining population sizes? and (b) how does dispersal influence the spatial distribution patterns of abundances among connected populations? We approached these questions with a simulation model of populations on a coupled lattice with cells of continuously varying habitat quality expressed as carrying capacities. Each cell contained a population with the basic dynamics of density-regulated growth, and was connected to other populations by immigration and emigration. The degree to which dispersal influenced the distribution of population sizes depended most strongly on the absolute amount of dispersal, and then on the potential population growth rate. Dispersal decaying in intensity with distance left close neighbours more alike in population size than distant populations, leading to an increase in spatial autocorrelation. The spatial distribution of species with low potential growth rates is more dependent on dispersal than that of species with high growth rates; therefore, distribution modelling for species with low growth rates requires particular attention to autocorrelation, and conservation management of these species requires attention to factors curtailing dispersal, such as fragmentation and dispersal barriers. ?? 2007 Elsevier B.V. All rights reserved.

The concept for realization of quantum-cascade lasers emitting at 7.5 μm wavelength

NASA Astrophysics Data System (ADS)

Novikov, I. I.; Babichev, A. V.; Bugrov, V. E.; Gladyshev, A. G.; Karachinsky, L. Ya; Kolodeznyi, E. S.; Kurochkin, A. S.; Savelyev, A. V.; Sokolovskii, G. S.; Egorov, A. Yu

2017-11-01

We consider the advantages and disadvantages of various designs of waveguide for heterostructures of quantum cascade lasers (QCL) in a spectral region of 7.5 μm. Based on a numerical calculation we make a comparison of light wave distribution in QCL waveguides with different designs. We demonstrate the benefits of practical QCL realization with an extended five-layered waveguide formed by introducing extra layers of InGaAs, which allows to modify the spatial distribution of the light wave and get the rectangular shape of the spatial distribution of light wave intensity in the laser active area.

Spatiotemporal variability of wildland fuels in US Northern Rocky Mountain forests

Treesearch

Robert E. Keane

2016-01-01

Fire regimes are ultimately controlled by wildland fuel dynamics over space and time; spatial distributions of fuel influence the size, spread, and intensity of individual fires, while the temporal distribution of fuel deposition influences fire's frequency and controls fire size. These "shifting fuel mosaics" are both a cause and a consequence...

Distribution of energetic oxygen and hydrogen in the near-Earth plasma sheet

NASA Astrophysics Data System (ADS)

Kronberg, E. A.; Grigorenko, E. E.; Haaland, S. E.; Daly, P. W.; Delcourt, D. C.; Luo, H.; Kistler, L. M.; Dandouras, I.

2015-05-01

The spatial distributions of different ion species are useful indicators for plasma sheet dynamics. In this statistical study based on 7 years of Cluster observations, we establish the spatial distributions of oxygen ions and protons at energies from 274 to 955 keV, depending on geomagnetic and solar wind (SW) conditions. Compared with protons, the distribution of energetic oxygen has stronger dawn-dusk asymmetry in response to changes in the geomagnetic activity. When the interplanetary magnetic field (IMF) is directed southward, the oxygen ions show significant acceleration in the tail plasma sheet. Changes in the SW dynamic pressure (Pdyn) affect the oxygen and proton intensities in the same way. The energetic protons show significant intensity increases at the near-Earth duskside during disturbed geomagnetic conditions, enhanced SW Pdyn, and southward IMF, implying there location of effective inductive acceleration mechanisms and a strong duskward drift due to the increase of the magnetic field gradient in the near-Earth tail. Higher losses of energetic ions are observed in the dayside plasma sheet under disturbed geomagnetic conditions and enhanced SW Pdyn. These observations are in agreement with theoretical models.

Hollow Gaussian beam generated by beam shaping with phase-only liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Nie, Yongming; Li, Xiujian; Qi, Junli; Ma, Haotong; Liao, Jiali; Yang, Jiankun; Hu, Wenhua

2012-03-01

Based on the refractive beam shaping system, the transformation of a quasi-Gaussian beam into a dark hollow Gaussian beam by a phase-only liquid crystal spatial light modulator (LC-SLM) is proposed. According to the energy conservation and constant optical path principle, the phase distribution of the aspheric lens and the phase-only LC-SLM can modulate the wave-front properly to generate the hollow beam. The numerical simulation results indicate that, the dark hollow intensity distribution of the output shaped beam can be maintained well for a certain propagation distance during which the dark region will not decrease whereas the ideal hollow Gaussian beam will do. By designing the phase modulation profile, which loaded into the LC-SLM carefully, the experimental results indicate that the dark hollow intensity distribution of the output shaped beam can be maintained well even at a distance much more than 550 mm from the LC-SLM, which agree with the numerical simulation results.

Regulation of Oligomeric Organization of the Serotonin 5-Hydroxytryptamine 2C (5-HT2C) Receptor Observed by Spatial Intensity Distribution Analysis*

PubMed Central

Ward, Richard J.; Pediani, John D.; Godin, Antoine G.; Milligan, Graeme

2015-01-01

The questions of whether G protein-coupled receptors exist as monomers, dimers, and/or oligomers and if these species interconvert in a ligand-dependent manner are among the most contentious current issues in biology. When employing spatial intensity distribution analysis to laser scanning confocal microscope images of cells stably expressing either a plasma membrane-associated form of monomeric enhanced green fluorescent protein (eGFP) or a tandem version of this fluorophore, the eGFP tandem was identified as a dimer. Similar studies on cells stably expressing an eGFP-tagged form of the epidermal growth factor receptor demonstrated that, although largely a monomer in the basal state, this receptor rapidly became predominantly dimeric upon the addition of its ligand epidermal growth factor. In cells induced to express an eGFP-tagged form of the serotonin 5-hydroxytryptamine 2C (5-HT2C) receptor, global analysis of construct quantal brightness was consistent with the predominant form of the receptor being dimeric. However, detailed spatial intensity distribution analysis demonstrated the presence of multiple forms ranging from monomers to higher-order oligomers. Furthermore, treatment with chemically distinct 5-HT2C receptor antagonists resulted in a time-dependent change in the quaternary organization to one in which there was a preponderance of receptor monomers. This antagonist-mediated effect was reversible, because washout of the ligand resulted in the regeneration of many of the oligomeric forms of the receptor. PMID:25825490

Initial assessment of the intensity distribution of the 2011 Mw5.8 Mineral, Virginia, earthquake

USGS Publications Warehouse

Hough, Susan E.

2012-01-01

The intensity data collected by the U.S. Geological Survey (USGS) "Did You Feel It?" (DYFI) Website (USGS, DYFI; http://earthquake.usgs.gov/earthquakes/dyfi/events/se/082311a/us/index.html, last accessed Sept 2011) for the Mw5.8 Mineral, Virginia, earthquake, are unprecedented in their spatial richness and geographical extent. More than 133,000 responses were received during the first week following the earthquake. Although intensity data have traditionally been regarded as imprecise and generally suspect (e.g., Hough 2000), there is a growing appreciation for the potential utility of spatially rich, systematically determined DYFI data to address key questions in earthquake ground-motions science (Atkinson and Wald, 2007; Hauksson et al., 2008).

Impact of temporal, spatial and cascaded effects on the pulse formation in ultra-broadband parametric amplifiers.

PubMed

Lang, T; Harth, A; Matyschok, J; Binhammer, T; Schultze, M; Morgner, U

2013-01-14

A 2 + 1 dimensional nonlinear pulse propagation model is presented, illustrating the weighting of different effects for the parametric amplification of ultra-broadband spectra in different regimes of energy scaling. Typical features in the distribution of intensity and phase of state-of-the-art OPA-systems can be understood by cascaded spatial and temporal effects.

Brain MR image segmentation based on an improved active contour model

PubMed Central

Meng, Xiangrui; Gu, Wenya; Zhang, Jianwei

2017-01-01

It is often a difficult task to accurately segment brain magnetic resonance (MR) images with intensity in-homogeneity and noise. This paper introduces a novel level set method for simultaneous brain MR image segmentation and intensity inhomogeneity correction. To reduce the effect of noise, novel anisotropic spatial information, which can preserve more details of edges and corners, is proposed by incorporating the inner relationships among the neighbor pixels. Then the proposed energy function uses the multivariate Student's t-distribution to fit the distribution of the intensities of each tissue. Furthermore, the proposed model utilizes Hidden Markov random fields to model the spatial correlation between neigh-boring pixels/voxels. The means of the multivariate Student's t-distribution can be adaptively estimated by multiplying a bias field to reduce the effect of intensity inhomogeneity. In the end, we reconstructed the energy function to be convex and calculated it by using the Split Bregman method, which allows our framework for random initialization, thereby allowing fully automated applications. Our method can obtain the final result in less than 1 second for 2D image with size 256 × 256 and less than 300 seconds for 3D image with size 256 × 256 × 171. The proposed method was compared to other state-of-the-art segmentation methods using both synthetic and clinical brain MR images and increased the accuracies of the results more than 3%. PMID:28854235

Development and relationship of monogenetic and polygenetic volcanic fields in time and space.

NASA Astrophysics Data System (ADS)

Germa, Aurelie; Connor, Chuck; Connor, Laura; Malservisi, Rocco

2013-04-01

The classification of volcanic systems, developed by G. P. L. Walker and colleagues, relates volcano morphology to magma transport and eruption processes. In general, distributed monogenetic volcanic fields are characterized by infrequent eruptions, low average output rate, and a low spatial intensity of the eruptive vents. In contrast, central-vent-dominated systems, such as stratovolcanoes, central volcanoes and lava shields are characterized by frequent eruptions, higher average flux rates, and higher spatial intensity of eruptive vents. However, it has been observed that a stratovolcano is often associated to parasitic monogenetic vents on its flanks, related to the central silicic systems, and surrounded by an apron of monogenetic edifices that are part of the volcanic field but independent from the principal central system. It appears from spatial distribution and time-volume relationships that surface area of monogenetic fields reflects the lateral extent of the magma source region and the lack of magma focusing mechanisms. In contrast, magma is focused through a unique conduit system for polygenetic volcanoes, provided by a thermally and mechanically favorable pathway toward the surface that is maintained by frequent and favorable stress conditions. We plan to relate surface observations of spatio-temporal location of eruptive vents and evolution of the field area through time to processes that control magma focusing during ascent and storage in the crust. We choose to study fields that range from dispersed to central-vent dominated, through transitional fields (central felsic system with peripheral field of monogenetic vents independent from the rhyolitic system). We investigate different well-studied volcanic fields in the Western US and Western Europe in order to assess influence of the geodynamic setting and tectonic stress on the spatial distribution of magmatism. In summary, incremental spatial intensity maps should reveal how fast a central conduit is created during the development of a volcanic field, and how this could influence the outbreak of dispersed monogenetic volcanoes that are not geochemically linked to the central system.

Multistage Spatial Property Based Segmentation for Quantification of Fluorescence Distribution in Cells

NASA Astrophysics Data System (ADS)

Zhang, Guangyun; Jia, Xiuping; Pham, Tuan D.; Crane, Denis I.

2010-01-01

The interpretation of the distribution of fluorescence in cells is often by simple visualization of microscope-derived images for qualitative studies. In other cases, however, it is desirable to be able to quantify the distribution of fluorescence using digital image processing techniques. In this paper, the challenges of fluorescence segmentation due to the noise present in the data are addressed. We report that intensity measurements alone do not allow separation of overlapping data between target and background. Consequently, spatial properties derived from neighborhood profile were included. Mathematical Morphological operations were implemented for cell boundary extraction and a window based contrast measure was developed for fluorescence puncta identification. All of these operations were applied in the proposed multistage processing scheme. The testing results show that the spatial measures effectively enhance the target separability.

Continuous rainfall simulation for regional flood risk assessment - application in the Austrian Alps

NASA Astrophysics Data System (ADS)

Salinas, Jose Luis; Nester, Thomas; Komma, Jürgen; Blöschl, Günter

2017-04-01

Generation of realistic synthetic spatial rainfall is of pivotal importance for assessing regional hydroclimatic hazard as the input for long term rainfall-runoff simulations. The correct reproduction of the observed rainfall characteristics, such as regional intensity-duration-frequency curves, is necessary to adequately model the magnitude and frequency of the flood peaks. Furthermore, the replication of the observed rainfall spatial and temporal correlations allows to model important other hydrological features like antecedent soil moisture conditions before extreme rainfall events. In this work, we present an application in the Tirol region (Austrian alps) of a modification of the model presented by Bardossy and Platte (1992), where precipitation is modeled on a station basis as a mutivariate autoregressive model (mAr) in a Normal space, and then transformed to a Gamma-distributed space. For the sake of simplicity, the parameters of the Gamma distributions are assumed to vary monthly according to a sinusoidal function, and are calibrated trying to simultaneously reproduce i) mean annual rainfall, ii) mean daily rainfall amounts, iii) standard deviations of daily rainfall amounts, and iv) 24-hours intensity duration frequency curve. The calibration of the spatial and temporal correlation parameters is performed in a way that the intensity-duration-frequency curves aggregated at different spatial and temporal scales reproduce the measured ones. Bardossy, A., and E. J. Plate (1992), Space-time model for daily rainfall using atmospheric circulation patterns, Water Resour. Res., 28(5), 1247-1259, doi:10.1029/91WR02589.

Spatial and temporal variations of aerosols around Beijing in summer 2006: Model evaluation and source apportionment

NASA Astrophysics Data System (ADS)

Matsui, H.; Koike, M.; Kondo, Y.; Takegawa, N.; Kita, K.; Miyazaki, Y.; Hu, M.; Chang, S.; Blake, D. R.; Fast, J. D.; Zaveri, R. A.; Streets, D. G.; Zhang, Q.; Zhu, T.

2009-12-01

Regional aerosol model calculations were made using the WRF-CMAQ and WRF-chem models to study spatial and temporal variations of aerosols around Beijing, China, in the summer of 2006, when the CAREBEIJING-2006 intensive campaign was conducted. Model calculations captured temporal variations of primary (such as elemental carbon, EC) and secondary (such as sulfate) aerosols observed in and around Beijing. The spatial distributions of aerosol optical depth observed by the MODIS satellite sensors were also reproduced over northeast China. Model calculations showed distinct differences in spatial distributions between primary and secondary aerosols in association with synoptic-scale meteorology. Secondary aerosols increased in air around Beijing on a scale of about 1000 x 1000 km2 under an anticyclonic pressure system. This airmass was transported northward from the high anthropogenic emission area extending south of Beijing with continuous photochemical production. Subsequent cold front passage brought clean air from the north, and polluted air around Beijing was swept to the south of Beijing. This cycle was repeated about once a week and was found to be responsible for observed enhancements/reductions of aerosols at the intensive measurement sites. In contrast to secondary aerosols, the spatial distributions of primary aerosols (EC) reflected those of emissions, resulting in only slight variability despite the changes in synoptic-scale meteorology. In accordance with these results, source apportionment simulations revealed that primary aerosols around Beijing were controlled by emissions within 100 km around Beijing within the preceding 24 hours, while emissions as far as 500 km and within the preceding 3 days were found to affect secondary aerosols.

Spatial and seasonal dynamics of brook trout populations inhabiting a central Appalachian watershed

USGS Publications Warehouse

Petty, J.T.; Lamothe, P.J.; Mazik, P.M.

2005-01-01

We quantified the watershed-scale spatial population dynamics of brook trout Salvelinus fontinalis in the Second Fork, a third-order tributary of Shavers Fork in eastern West Virginia. We used visual surveys, electrofishing, and mark-recapture techniques to quantify brook trout spawning intensity, population density, size structure, and demographic rates (apparent survival and immigration) throughout the watershed. Our analyses produced the following results. Spawning by brook trout was concentrated in streams with small basin areas (i.e., segments draining less than 3 km2), relatively high alkalinity (>10 mg CaCO3/L), and high amounts of instream cover. The spatial distribution of juvenile and small-adult brook trout within the watershed was relatively stable and was significantly correlated with spawning intensity. However, no such relationship was observed for large adults, which exhibited highly variable distribution patterns related to seasonally important habitat features, including instream cover, stream depth and width, and riparian canopy cover. Brook trout survival and immigration rates varied seasonally, spatially, and among size-classes. Differential survival and immigration tended to concentrate juveniles and small adults in small, alkaline streams, whereas dispersal tended to redistribute large adults at the watershed scale. Our results suggest that spatial and temporal variations in spawning, survival, and movement interact to determine the distribution, abundance, and size structure of brook trout populations at a watershed scale. These results underscore the importance of small tributaries for the persistence of brook trout in this watershed and the need to consider watershed-scale processes when designing management plans for Appalachian brook trout populations. ?? Copyright by the American Fisheries Society 2005.

Using pixel intensity as a self-regulating threshold for deterministic image sampling in Milano Retinex: the T-Rex algorithm

NASA Astrophysics Data System (ADS)

Lecca, Michela; Modena, Carla Maria; Rizzi, Alessandro

2018-01-01

Milano Retinexes are spatial color algorithms, part of the Retinex family, usually employed for image enhancement. They modify the color of each pixel taking into account the surrounding colors and their position, catching in this way the local spatial color distribution relevant to image enhancement. We present T-Rex (from the words threshold and Retinex), an implementation of Milano Retinex, whose main novelty is the use of the pixel intensity as a self-regulating threshold to deterministically sample local color information. The experiments, carried out on real-world pictures, show that T-Rex image enhancement performance are in line with those of the Milano Retinex family: T-Rex increases the brightness, the contrast, and the flatness of the channel distributions of the input image, making more intelligible the content of pictures acquired under difficult light conditions.

Synchronous characterization of semiconductor microcavity laser beam.

PubMed

Wang, T; Lippi, G L

2015-06-01

We report on a high-resolution double-channel imaging method used to synchronously map the intensity- and optical-frequency-distribution of a laser beam in the plane orthogonal to the propagation direction. The synchronous measurement allows us to show that the laser frequency is an inhomogeneous distribution below threshold, but that it becomes homogeneous across the fundamental Gaussian mode above threshold. The beam's tails deviations from the Gaussian shape, however, are accompanied by sizeable fluctuations in the laser wavelength, possibly deriving from manufacturing details and from the influence of spontaneous emission in the very low intensity wings. In addition to the synchronous spatial characterization, a temporal analysis at any given point in the beam cross section is carried out. Using this method, the beam homogeneity and spatial shape, energy density, energy center, and the defects-related spectrum can also be extracted from these high-resolution pictures.

Estimation of the vortex length scale and intensity from two-dimensional samples

NASA Technical Reports Server (NTRS)

Reuss, D. L.; Cheng, W. P.

1992-01-01

A method is proposed for estimating flow features that influence flame wrinkling in reciprocating internal combustion engines, where traditional statistical measures of turbulence are suspect. Candidate methods were tested in a computed channel flow where traditional turbulence measures are valid and performance can be rationally evaluated. Two concepts are tested. First, spatial filtering is applied to the two-dimensional velocity distribution and found to reveal structures corresponding to the vorticity field. Decreasing the spatial-frequency cutoff of the filter locally changes the character and size of the flow structures that are revealed by the filter. Second, vortex length scale and intensity is estimated by computing the ensemble-average velocity distribution conditionally sampled on the vorticity peaks. The resulting conditionally sampled 'average vortex' has a peak velocity less than half the rms velocity and a size approximately equal to the two-point-correlation integral-length scale.

High spatial resolution distributed fiber system for multi-parameter sensing based on modulated pulses.

PubMed

Zhang, Jingdong; Zhu, Tao; Zhou, Huan; Huang, Shihong; Liu, Min; Huang, Wei

2016-11-28

We demonstrate a cost-effective distributed fiber sensing system for the multi-parameter detection of the vibration, the temperature, and the strain by integrating phase-sensitive optical time domain reflectometry (φ-OTDR) and Brillouin optical time domain reflectometry (B-OTDR). Taking advantage of the fast changing property of the vibration and the static properties of the temperature and the strain, both the width and intensity of the laser pulses are modulated and injected into the single-mode sensing fiber proportionally, so that three concerned parameters can be extracted simultaneously by only one photo-detector and one data acquisition channel. A data processing method based on Gaussian window short time Fourier transform (G-STFT) is capable of achieving high spatial resolution in B-OTDR. The experimental results show that up to 4.8kHz vibration sensing with 3m spatial resolution at 10km standard single-mode fiber can be realized, as well as the distributed temperature and stress profiles along the same fiber with 80cm spatial resolution.

GIS-based evaluation and spatial distribution characteristics of land degradation in Bijiang watershed.

PubMed

Zhao, Xiaoqing; Dai, Jinhua; Wang, Jianping

2013-01-01

Land degradation is one of the significant issues the human beings are confronted with, which has become a bottleneck of restricting the sustainable development of the regional society and economy. In order to ascertain the root causes contributed to the land degradation and characteristics of land degradation, Bijiang watershed, the most important Lead-Zinc mine area of Lanping county of Yunnan Province, was selected as the study area. One evaluation index system for land degradation that consists of 5 single factors(water-soil erosion intensity, geological disaster risk, cultivation intensity of arable land, pollution of heavy metals in soil and biodiversity deterioration) was established and 13 indicators were chosen, and the entropy method was adopted to assign weights to each single factor. By using the tools of Geographic Information System (GIS), the land degradation degree was evaluated and one spatial distribution map for land degradation was accomplished. In this study, the land of the whole watershed was divided into 4 types, including extremely-severe degradation area, severely-degraded area, moderately-degraded area and slightly-degraded area, and some solutions for ecological restoration and rehabilitation were also put forward in this study. The study results indicated that: (1) Water-soil erosion intension and pollution of heavy metals in soil have made greater contribution to the comprehensive land degradation in Bijiang watershed; (2) There is an apparent difference regarding land degradation degree in Bijiang watershed. The moderately-degraded area accounts for the most part in the region, which covers 79.66% of the whole watershed. The severely-degraded area accounts for 15.98% and the slightly-degraded regions and extremely severe degradation area accounts for 1.08% and 3.28% respectively; (3) There is an evident regularity of spatial distribution in land degradation in Bijiang watershed. The moderately-degraded areas mainly distribute in the most part of the mid-stream and down-stream, the slightly-degraded areas distribute in the mid-stream, the severely-degraded areas distribute in the upstream and south-west part of down-stream, the extremely severe degradation areas distribute in the east and middle part of the upstream; (4)From the administrative division viewpoint, the slightly-degraded areas primarily distribute in Jiancao township, Baishi town and Nuodeng town. The moderately-degraded areas distribute in Changxin township, Baofeng township, Jiancao township, Baishi town and Nuodeng town. The severely-degraded areas distribute in Jinding town, Baofeng township and Lajing town. The extremely severe degradation areas distribute in Jinding town. By connecting the spatial distribution mode for land degradation with other natural, economical elements, we drew a conclusion that the pollution in heavy metals in soil, serious water erosion and geological disasters are the main causes of the land degradation in Bijiang watershed.

Imaging optical fields below metal films and metal-dielectric waveguides by a scanning microscope

NASA Astrophysics Data System (ADS)

Zhu, Liangfu; Wang, Yong; Zhang, Douguo; Wang, Ruxue; Qiu, Dong; Wang, Pei; Ming, Hai; Badugu, Ramachandram; Rosenfeld, Mary; Lakowicz, Joseph R.

2017-09-01

Laser scanning confocal fluorescence microscopy (LSCM) is now an important method for tissue and cell imaging when the samples are located on the surfaces of glass slides. In the past decade, there has been extensive development of nano-optical structures that display unique effects on incident and transmitted light, which will be used with novel configurations for medical and consumer products. For these applications, it is necessary to characterize the light distribution within short distances from the structures for efficient detection and elimination of bulky optical components. These devices will minimize or possibly eliminate the need for free-space light propagation outside of the device itself. We describe the use of the scanning function of a LSCM to obtain 3D images of the light intensities below the surface of nano-optical structures. More specifically, we image the spatial distributions inside the substrate of fluorescence emission coupled to waveguide modes after it leaks through thin metal films or dielectric-coated metal films. The observed spatial distribution were in general agreement with far-field calculations, but the scanning images also revealed light intensities at angles not observed with classical back focal plane imaging. Knowledge of the subsurface optical intensities will be crucial in the combination of nano-optical structures with rapidly evolving imaging detectors.

Three-dimensional characterization of tightly focused fields for various polarization incident beams

NASA Astrophysics Data System (ADS)

Cai, Yanan; Liang, Yansheng; Lei, Ming; Yan, Shaohui; Wang, Zhaojun; Yu, Xianghua; Li, Manman; Dan, Dan; Qian, Jia; Yao, Baoli

2017-06-01

Tightly focused vectorial optical beams have found extensive applications in variety of technical fields like single-molecule detection, optical tweezers, and super-resolution optical microscopy. Such applications require an accurate measurement and manipulation of focal optical fields. We have developed a compact instrument (with dimensions of 35 × 35 × 30 cm3) to rapidly measure the intensity distribution in three dimensions of the focused fields of vectorial beams and any other incident beams. This instrument employs a fluorescent nanoparticle as a probe to scan the focal region to obtain a high spatial resolution of intensity distribution. It integrates a liquid-crystal spatial light modulator to allow for tailoring the point spread function of the optical system, making it a useful tool for multi-purpose and flexible research. The robust applicability of the instrument is verified by measuring the 3D intensity distributions of focal fields of various polarization and wavefront modulated incident beams focused by a high NA (=1.25) objective lens. The minimal data acquisition time achievable in the experiment is about 8 s for a scanning region of 3.2 × 3.2 μm2 (512 × 512 pixels). The measured results are in good agreement with those predicted by the vectorial diffraction theory.

Using spatial principles to optimize distributed computing for enabling the physical science discoveries

PubMed Central

Yang, Chaowei; Wu, Huayi; Huang, Qunying; Li, Zhenlong; Li, Jing

2011-01-01

Contemporary physical science studies rely on the effective analyses of geographically dispersed spatial data and simulations of physical phenomena. Single computers and generic high-end computing are not sufficient to process the data for complex physical science analysis and simulations, which can be successfully supported only through distributed computing, best optimized through the application of spatial principles. Spatial computing, the computing aspect of a spatial cyberinfrastructure, refers to a computing paradigm that utilizes spatial principles to optimize distributed computers to catalyze advancements in the physical sciences. Spatial principles govern the interactions between scientific parameters across space and time by providing the spatial connections and constraints to drive the progression of the phenomena. Therefore, spatial computing studies could better position us to leverage spatial principles in simulating physical phenomena and, by extension, advance the physical sciences. Using geospatial science as an example, this paper illustrates through three research examples how spatial computing could (i) enable data intensive science with efficient data/services search, access, and utilization, (ii) facilitate physical science studies with enabling high-performance computing capabilities, and (iii) empower scientists with multidimensional visualization tools to understand observations and simulations. The research examples demonstrate that spatial computing is of critical importance to design computing methods to catalyze physical science studies with better data access, phenomena simulation, and analytical visualization. We envision that spatial computing will become a core technology that drives fundamental physical science advancements in the 21st century. PMID:21444779

Using spatial principles to optimize distributed computing for enabling the physical science discoveries.

PubMed

Yang, Chaowei; Wu, Huayi; Huang, Qunying; Li, Zhenlong; Li, Jing

2011-04-05

Contemporary physical science studies rely on the effective analyses of geographically dispersed spatial data and simulations of physical phenomena. Single computers and generic high-end computing are not sufficient to process the data for complex physical science analysis and simulations, which can be successfully supported only through distributed computing, best optimized through the application of spatial principles. Spatial computing, the computing aspect of a spatial cyberinfrastructure, refers to a computing paradigm that utilizes spatial principles to optimize distributed computers to catalyze advancements in the physical sciences. Spatial principles govern the interactions between scientific parameters across space and time by providing the spatial connections and constraints to drive the progression of the phenomena. Therefore, spatial computing studies could better position us to leverage spatial principles in simulating physical phenomena and, by extension, advance the physical sciences. Using geospatial science as an example, this paper illustrates through three research examples how spatial computing could (i) enable data intensive science with efficient data/services search, access, and utilization, (ii) facilitate physical science studies with enabling high-performance computing capabilities, and (iii) empower scientists with multidimensional visualization tools to understand observations and simulations. The research examples demonstrate that spatial computing is of critical importance to design computing methods to catalyze physical science studies with better data access, phenomena simulation, and analytical visualization. We envision that spatial computing will become a core technology that drives fundamental physical science advancements in the 21st century.

Community- Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance

PubMed Central

Jeltsch, Florian; Wurst, Susanne

2015-01-01

Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae) larvae (43%) in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height), and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio). Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of insect root herbivores with large, fast growing plants may counteract dominance of those species, thus promoting plant diversity. PMID:26517119

Fisheye camera method for spatial non-uniformity corrections in luminous flux measurements with integrating spheres

NASA Astrophysics Data System (ADS)

Kokka, Alexander; Pulli, Tomi; Poikonen, Tuomas; Askola, Janne; Ikonen, Erkki

2017-08-01

This paper presents a fisheye camera method for determining spatial non-uniformity corrections in luminous flux measurements with integrating spheres. Using a fisheye camera installed into a port of an integrating sphere, the relative angular intensity distribution of the lamp under test is determined. This angular distribution is used for calculating the spatial non-uniformity correction for the lamp when combined with the spatial responsivity data of the sphere. The method was validated by comparing it to a traditional goniophotometric approach when determining spatial correction factors for 13 LED lamps with different angular spreads. The deviations between the spatial correction factors obtained using the two methods ranged from -0.15 % to 0.15%. The mean magnitude of the deviations was 0.06%. For a typical LED lamp, the expanded uncertainty (k = 2 ) for the spatial non-uniformity correction factor was evaluated to be 0.28%. The fisheye camera method removes the need for goniophotometric measurements in determining spatial non-uniformity corrections, thus resulting in considerable system simplification. Generally, no permanent modifications to existing integrating spheres are required.

Fractional Fourier transform of Lorentz-Gauss vortex beams

NASA Astrophysics Data System (ADS)

Zhou, GuoQuan; Wang, XiaoGang; Chu, XiuXiang

2013-08-01

An analytical expression for a Lorentz-Gauss vortex beam passing through a fractional Fourier transform (FRFT) system is derived. The influences of the order of the FRFT and the topological charge on the normalized intensity distribution, the phase distribution, and the orbital angular momentum density of a Lorentz-Gauss vortex beam in the FRFT plane are examined. The order of the FRFT controls the beam spot size, the orientation of the beam spot, the spiral direction of the phase distribution, the spatial orientation of the two peaks in the orbital angular momentum density distribution, and the magnitude of the orbital angular momentum density. The increase of the topological charge not only results in the dark-hollow region becoming large, but also brings about detail changes in the beam profile. The spatial orientation of the two peaks in the orbital angular momentum density distribution and the phase distribution also depend on the topological charge.

Spatial distribution on high-order-harmonic generation of an H2+ molecule in intense laser fields

NASA Astrophysics Data System (ADS)

Zhang, Jun; Ge, Xin-Lei; Wang, Tian; Xu, Tong-Tong; Guo, Jing; Liu, Xue-Shen

2015-07-01

High-order-harmonic generation (HHG) for the H2 + molecule in a 3-fs, 800-nm few-cycle Gaussian laser pulse combined with a static field is investigated by solving the one-dimensional electronic and one-dimensional nuclear time-dependent Schrödinger equation within the non-Born-Oppenheimer approximation. The spatial distribution in HHG is demonstrated and the results present the recombination process of the electron with the two nuclei, respectively. The spatial distribution of the HHG spectra shows that there is little possibility of the recombination of the electron with the nuclei around the origin z =0 a.u. and equilibrium internuclear positions z =±1.3 a.u. This characteristic is irrelevant to laser parameters and is only attributed to the molecular structure. Furthermore, we investigate the time-dependent electron-nuclear wave packet and ionization probability to further explain the underlying physical mechanism.

Generation of dark hollow femtosecond pulsed beam by phase-only liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Nie, Yongming; Ma, Haotong; Li, Xiujian; Hu, Wenhua; Yang, Jiankun

2011-07-01

Based on the refractive laser beam shaping system, the dark hollow femtosecond pulse beam shaping technique with a phase-only liquid crystal spatial light modulator (LC-SLM) is demonstrated. The phase distribution of the LC-SLM is derived by the energy conservation and constant optical path principle. The effects of the shaping system on the temporal properties, including spectral phase distribution and bandwidth of the femtosecond pulse, are analyzed in detail. Experimental results show that the hollow intensity distribution of the output pulsed beam can be maintained much at more than 1200mm. The spectral phase of the pulse is changed, and the pulse width is expanded from 199 to 230fs, which is caused by the spatial--temporal coupling effect. The coupling effect mainly depends on the phase-only LC-SLM itself, not on its loaded phase distribution. The experimental results indicate that the proposed shaping setup can generate a dark hollow femtosecond pulsed beam effectively, because the temporal Gaussian waveform is unchanged.

Effects of spatial transport and ambient wave intensity on the generation of MHD waves by interstellar pickup protons

NASA Technical Reports Server (NTRS)

Isenberg, P. A.

1995-01-01

Intense MHD waves generated by the isotropization of interstellar pickup protons were predicted by Lee and Ip (1987) to appear in the solar wind whenever pickup proton fluxes were high enough. However, in reality these waves have proved surprisingly difficult to identify, even in the presence of observed pickup protons. We investigate the wave excitation by isotropization from an initially broad pitch-angle distribution instead of the narrow ring-beam assumed by Lee and Ip. The pitch angle of a newly-ionized proton is given by theta(sub o), the angle between the magnetic field (averaged over a pickup proton gyroradius) and the solar wind flow at the time of ionization. Then, a broadened distribution results from spatial transport of pickup protons prior to isotropization from regions upstream along the field containing different values of theta(sub o). The value of theta(sub o) will vary as a result of the ambient long-wavelength fluctuations in the solar wind. Thus, the range of initial pitch-angles is directly related to the amplitude of these fluctuations within a length-scale determined by the isotropization time. We show that a broad initial pitch-angle distribution can significantly modify the intensity and shape of the pickup-proton-generated wave spectrum, and we derive a criterion for the presence of observable pickup-proton generated waves given the intensity of the ambient long wavelength fluctuations.

Diffraction of cosine-Gaussian-correlated Schell-model beams.

PubMed

Pan, Liuzhan; Ding, Chaoliang; Wang, Haixia

2014-05-19

The expression of spectral density of cosine-Gaussian-correlated Schell-model (CGSM) beams diffracted by an aperture is derived, and used to study the changes in the spectral density distribution of CGSM beams upon propagation, where the effect of aperture diffraction is emphasized. It is shown that, comparing with that of GSM beams, the spectral density distribution of CGSM beams diffracted by an aperture has dip and shows dark hollow intensity distribution when the order-parameter n is big enough. The central intensity increases with increasing truncation parameter of aperture. The comparative study of spectral density distributions of CGSM beams with aperture and that of without aperture is performed. Furthermore, the effect of order-parameter n and spatial coherence of CGSM beams on the spectral density distribution is discussed in detail. The results obtained may be useful in optical particulate manipulation.

[Emission Characteristics of Vehicle Exhaust in Beijing Based on Actual Traffic Flow Information].

PubMed

Fan, Shou-bin; Tian, Ling-di; Zhang, Dong-xu; Qu, Song

2015-08-01

The basic data of traffic volume, vehicle type constitute and speed on road networks in Beijing was obtained fly modei simulation and field survey. Based on actual traffic flow information and. emission factors data with temporal and spatial distribution features, emission inventory of motor vehicle exhaust in Beijing was built on the ArcGIS platform, meanwhile, the actual road emission characteristics and spatial distribution of the pollutant emissions were analyzed. The results showed that the proportion of passenger car was higher than 89% on each type of road in the urban, and the proportion of passenger car was the highest in suburban roads as well while the pickup truck, medium truck, heavy truck, motorbus, tractor and motorcycle also occupied a certain proportion. There was a positive correlation between the pollutant emission intensity and traffic volume, and the emission intensity was generally higher in daytime than nighttime, but the diurnal variation trend of PM emission was not clear for suburban roads and the emission intensity was higher in nighttime than daytime for highway. The emission intensities in urban area, south, southeast and northeast areas near urban were higher than those in the western and northern mountainous areas with lower density of road network. The ring roads in urban and highways in suburban had higher emission intensity because of the heavy traffic volume.

Spatial distribution of total phenolic content, enzymatic activities and browning in white yam (Dioscorea rotundata) tubers.

PubMed

Graham-Acquaah, Seth; Ayernor, George Sodah; Bediako-Amoa, Betty; Saalia, Firibu Kwesi; Afoakwa, Emmanuel Ohene

2014-10-01

Browning in raw and processed yams resulting from enzymes, polyphenol oxidase (PPO) and peroxidase (POD), activities is a major limitation to the industrial utilization of Dioscorea varieties of yams. Two elite cultivars of D. rotundata species were selected to study the spatial distribution of total phenols and enzymes (PPO and POD) activities. The intensities of tissue darkening in fresh yam chips prepared from the tuber sections of cultivars during frozen storage were also studied. Total phenolic content was observed to be highest in the head and mid sections of the cultivars than at the tail end. PPO activity did not have any specific distribution pattern whereas POD activity was found to be more concentrated in the head than in the middle and tail regions. Browning was found to be most intense in the head regions of the two cultivars studied; and was observed to correlate with total phenol and dry matter contents of tubers. Between the two enzymes, POD activity appeared to be more related to browning than PPO.

Effects of air-exposure gradients on spatial infection patterns of Perkinsus marinus in the eastern oyster Crassostrea virginica.

PubMed

Malek, Jennafer C; Breitburg, Denise L

2016-02-25

Spatial distributions of species can be shaped by factors such as parasites, mortality, and reproduction, all of which may be influenced by differences in physical factors along environmental gradients. In nearshore tidal waters, an elevational gradient in aerial exposure during low tide can shape the spatial distributions of benthic marine organisms. The eastern oyster Crassostrea virginica is an ecologically and economically important species that can dominate both subtidal and intertidal habitats along the east coast of the USA. Our goal was to determine whether prevalence and intensity of Perkinsus marinus (the causative agent of Dermo disease) infections vary along intertidal to subtidal gradients during summer. We used (1) field experiments conducted at 4 sites in the Chesapeake Bay and a Virginia coastal bay, (2) a controlled air-exposure experiment, and (3) field surveys from 7 sites ranging from Maine to North Carolina to test for effects of tidal exposure on infection. Results from our field surveys suggested that high intertidal oysters tend to have higher infection prevalence than subtidal oysters, but there was no effect on infection intensity. Field experiments rarely yielded significant effects of tidal exposure on infection prevalence and intensity. Overall, our study shows that exposure to air may not be a strong driver of infection patterns in this host-parasite system.

Impacts of Non-Stationarity in Climate on Flood Intensity-Duration-Frequency: Case Studies in Mountainous Areas with Snowmelt

NASA Astrophysics Data System (ADS)

Hou, Z.; Ren, H.; Sun, N.; Leung, L. R.; Liu, Y.; Coleman, A. M.; Skaggs, R.; Wigmosta, M. S.

2017-12-01

Hydrologic engineering design usually involves intensity-duration-frequency (IDF) analysis for calculating runoff from a design storm of specified precipitation frequency and duration using event-based hydrologic rainfall-runoff models. Traditionally, the procedure assumes climate stationarity and neglects snowmelt-driven runoff contribution to floods. In this study, we used high resolution climate simulations to provide inputs to the physics-based Distributed Hydrology Soil and Vegetation Model (DHSVM) to determine the spatially distributed precipitation and snowmelt available for runoff. Climate model outputs were extracted around different mountainous field sites in Colorado and California. IDF curves were generated at each numerical grid of DHSVM based on the simulated precipitation, temperature, and available water for runoff. Quantitative evaluation of trending and stationarity tests were conducted to identify (quasi-)stationary time periods for reliable IDF analysis. The impact of stationarity was evaluated by comparing the derived IDF attributes with respect to time windows of different length and level of stationarity. Spatial mapping of event return-period was performed for various design storms, and spatial mapping of event intensity was performed for given duration and return periods. IDF characteristics were systematically compared (historical vs RCP4.5 vs RCP8.5) using annual maximum series vs partial duration series data with the goal of providing reliable IDF analyses to support hydrologic engineering design.

Temporal and spatial distribution characteristics in the natural plague foci of Chinese Mongolian gerbils based on spatial autocorrelation.

PubMed

Du, Hai-Wen; Wang, Yong; Zhuang, Da-Fang; Jiang, Xiao-San

2017-08-07

The nest flea index of Meriones unguiculatus is a critical indicator for the prevention and control of plague, which can be used not only to detect the spatial and temporal distributions of Meriones unguiculatus, but also to reveal its cluster rule. This research detected the temporal and spatial distribution characteristics of the plague natural foci of Mongolian gerbils by body flea index from 2005 to 2014, in order to predict plague outbreaks. Global spatial autocorrelation was used to describe the entire spatial distribution pattern of the body flea index in the natural plague foci of typical Chinese Mongolian gerbils. Cluster and outlier analysis and hot spot analysis were also used to detect the intensity of clusters based on geographic information system methods. The quantity of M. unguiculatus nest fleas in the sentinel surveillance sites from 2005 to 2014 and host density data of the study area from 2005 to 2010 used in this study were provided by Chinese Center for Disease Control and Prevention. The epidemic focus regions of the Mongolian gerbils remain the same as the hot spot regions relating to the body flea index. High clustering areas possess a similar pattern as the distribution pattern of the body flea index indicating that the transmission risk of plague is relatively high. In terms of time series, the area of the epidemic focus gradually increased from 2005 to 2007, declined rapidly in 2008 and 2009, and then decreased slowly and began trending towards stability from 2009 to 2014. For the spatial change, the epidemic focus regions began moving northward from the southwest epidemic focus of the Mongolian gerbils from 2005 to 2007, and then moved from north to south in 2007 and 2008. The body flea index of Chinese gerbil foci reveals significant spatial and temporal aggregation characteristics through the employing of spatial autocorrelation. The diversity of temporary and spatial distribution is mainly affected by seasonal variation, the human activity and natural factors.

The relationship between extreme precipitation events and landslides distributions in 2009 in Lower Austria

NASA Astrophysics Data System (ADS)

Katzensteiner, H.; Bell, R.; Petschko, H.; Glade, T.

2012-04-01

The prediction and forecast of widespread landsliding for a given triggering event is an open research question. Numerous studies tried to link spatial rainfall and landslide distributions. This study focuses on analysing the relationship between intensive precipitation and rainfall-triggered shallow landslides in the year 2009 in Lower Austria. Landslide distributions were gained from the building ground register, which is maintained by the Geological Survey of Lower Austria. It contains detailed information of landslides, which were registered due to damage reports. Spatially distributed rainfall estimates were extracted from INCA (Integrated Nowcasting through Comprehensive Analysis) precipitation analysis, which is a combination of station data interpolation and radar data in a spatial resolution of 1km developed by the Central Institute for Meteorology and Geodynamics (ZAMG), Vienna, Austria. The importance of the data source is shown by comparing rainfall data based on reference gauges, spatial interpolation and INCA-analysis for a certain storm period. INCA precipitation data can detect precipitating cells that do not hit a station but might trigger a landslide, which is an advantage over the application of reference stations for the definition of rainfall thresholds. Empirical thresholds at regional scale were determined based on rainfall-intensity and duration in the year 2009 and landslide information. These thresholds are dependent on the criteria which separate the landslide triggering and non-triggering precipitation events from each other. Different approaches for defining thresholds alter the shape of the threshold as well. A temporarily threshold I=8,8263*D^(-0.672) for extreme rainfall events in summer in Lower Austria was defined. A verification of the threshold with similar events of other years as well as following analyses based on a larger landslide database are in progress.

Managing focal fields of vector beams with multiple polarization singularities.

PubMed

Han, Lei; Liu, Sheng; Li, Peng; Zhang, Yi; Cheng, Huachao; Gan, Xuetao; Zhao, Jianlin

2016-11-10

We explore the tight focusing behavior of vector beams with multiple polarization singularities, and analyze the influences of the number, position, and topological charge of the singularities on the focal fields. It is found that the ellipticity of the local polarization states at the focal plane could be determined by the spatial distribution of the polarization singularities of the vector beam. When the spatial location and topological charge of singularities have even-fold rotation symmetry, the transverse fields at the focal plane are locally linearly polarized. Otherwise, the polarization state becomes a locally hybrid one. By appropriately arranging the distribution of the polarization singularities in the vector beam, the polarization distributions of the focal fields could be altered while the intensity maintains unchanged.

Spatial and temporal variations of aerosols around Beijing in summer 2006: Model evaluation and source apportionment

NASA Astrophysics Data System (ADS)

Matsui, H.; Koike, M.; Kondo, Y.; Takegawa, N.; Kita, K.; Miyazaki, Y.; Hu, M.; Chang, S.-Y.; Blake, D. R.; Fast, J. D.; Zaveri, R. A.; Streets, D. G.; Zhang, Q.; Zhu, T.

2009-01-01

Regional aerosol model calculations were made using the Weather Research and Forecasting (WRF)-Community Multiscale Air Quality (CMAQ) and WRF-chem models to study spatial and temporal variations of aerosols around Beijing, China, in the summer of 2006, when the Campaigns of Air Quality Research in Beijing and Surrounding Region 2006 (CAREBeijing) intensive campaign was conducted. Model calculations captured temporal variations of primary (such as elemental carbon (EC)) and secondary (such as sulfate) aerosols observed in and around Beijing. The spatial distributions of aerosol optical depth observed by the MODIS satellite sensors were also reproduced over northeast China. Model calculations showed distinct differences in spatial distributions between primary and secondary aerosols in association with synoptic-scale meteorology. Secondary aerosols increased in air around Beijing on a scale of about 1000 × 1000 km2 under an anticyclonic pressure system. This air mass was transported northward from the high anthropogenic emission area extending south of Beijing with continuous photochemical production. Subsequent cold front passage brought clean air from the north, and polluted air around Beijing was swept to the south of Beijing. This cycle was repeated about once a week and was found to be responsible for observed enhancements/reductions of aerosols at the intensive measurement sites. In contrast to secondary aerosols, the spatial distributions of primary aerosols (EC) reflected those of emissions, resulting in only slight variability despite the changes in synoptic-scale meteorology. In accordance with these results, source apportionment simulations revealed that primary aerosols around Beijing were controlled by emissions within 100 km around Beijing within the preceding 24 h, while emissions as far as 500 km and within the preceding 3 days were found to affect secondary aerosols.

Spatial temperature distribution in human hairy and glabrous skin after infrared CO2 laser radiation

PubMed Central

2010-01-01

Background CO2 lasers have been used for several decades as an experimental non-touching pain stimulator. The laser energy is absorbed by the water content in the most superficial layers of the skin. The deeper located nociceptors are activated by passive conduction of heat from superficial to deeper skin layers. Methods In the current study, a 2D axial finite element model was developed and validated to describe the spatial temperature distribution in the skin after infrared CO2 laser stimulation. The geometry of the model was based on high resolution ultrasound scans. The simulations were compared to the subjective pain intensity ratings from 16 subjects and to the surface skin temperature distributions measured by an infrared camera. Results The stimulations were sensed significantly slower and less intense in glabrous skin than they were in hairy skin (MANOVA, p < 0.001). The model simulations of superficial temperature correlated with the measured skin surface temperature (r > 0.90, p < 0.001). Of the 16 subjects tested; eight subjects reported pricking pain in the hairy skin following a stimulus of 0.6 J/cm2 (5 W, 0.12 s, d1/e2 = 11.4 mm) only two reported pain to glabrous skin stimulation using the same stimulus intensity. The temperature at the epidermal-dermal junction (depth 50 μm in hairy and depth 133 μm in glabrous skin) was estimated to 46°C for hairy skin stimulation and 39°C for glabrous skin stimulation. Conclusions As compared to previous one dimensional heat distribution models, the current two dimensional model provides new possibilities for detailed studies regarding CO2 laser stimulation intensity, temperature levels and nociceptor activation. PMID:21059226

Distribution of the anticancer drugs doxorubicin, mitoxantrone and topotecan in tumors and normal tissues.

PubMed

Patel, Krupa J; Trédan, Olivier; Tannock, Ian F

2013-07-01

Pharmacokinetic analyses estimate the mean concentration of drug within a given tissue as a function of time, but do not give information about the spatial distribution of drugs within that tissue. Here, we compare the time-dependent spatial distribution of three anticancer drugs within tumors, heart, kidney, liver and brain. Mice bearing various xenografts were treated with doxorubicin, mitoxantrone or topotecan. At various times after injection, tumors and samples of heart, kidney, liver and brain were excised. Within solid tumors, the distribution of doxorubicin, mitoxantrone and topotecan was limited to perivascular regions at 10 min after administration and the distance from blood vessels at which drug intensity fell to half was ~25-75 μm. Although drug distribution improved after 3 and 24 h, there remained a significant decrease in drug fluorescence with increasing distance from tumor blood vessels. Drug distribution was relatively uniform in the heart, kidney and liver with substantially greater perivascular drug uptake than in tumors. There was significantly higher total drug fluorescence in the liver than in tumors after 10 min, 3 and 24 h. Little to no drug fluorescence was observed in the brain. There are marked differences in the spatial distributions of three anticancer drugs within tumor tissue and normal tissues over time, with greater exposure to most normal tissues and limited drug distribution to many cells in tumors. Studies of the spatial distribution of drugs are required to complement pharmacokinetic data in order to better understand and predict drug effects and toxicities.

Spatial heterogeneity distribution of soil total nitrogen and total phosphorus in the Yaoxiang watershed in a hilly area of northern China based on geographic information system and geostatistics.

PubMed

Liu, Yu; Gao, Peng; Zhang, Liyong; Niu, Xiang; Wang, Bing

2016-10-01

Soil total nitrogen (STN) and total phosphorus (STP) are important indicators of soil nutrients and the important indexes of soil fertility and soil quality evaluation. Using geographic information system (GIS) and geostatistics, the spatial heterogeneity distribution of STN and STP in the Yaoxiang watershed in a hilly area of northern China was studied. The results showed that: (1) The STN and STP contents showed a declining trend with the increase in soil depth; the variation coefficients ( C v ) of STN and STP in the 0- to 10-cm soil layer (42.25% and 14.77%, respectively) were higher than in the 10- to 30-cm soil layer (28.77% and 11.60%, respectively). Moreover, the C v of STN was higher than that of STP. (2) The maximum C 0 /( C 0  +  C 1 ) of STN and STP in the soil layers was less than 25%, this indicated that a strong spatial distribution autocorrelation existed for STN and STP; and the STP showed higher intensity and more stable variation than the STN. (3) From the correlation analysis, we concluded that the topographic indexes such as elevation and slope direction all influenced the spatial distribution of STN and STP (correlation coefficients were 0.688 and 0.518, respectively). (4) The overall distribution of STN and STP in the Yaoxiang watershed decreased from the northwest to the southeast. This variation trend was similar to the watershed DEM trend and was significantly influenced by vegetation and topographic factors. These results revealed the spatial heterogeneity distribution of STN and STP, and addressed the influences of forest vegetation coverage, elevation, and other topographic factors on the spatial distribution of STN and STP at the watershed scale.

Proton Energy Optimization and Spatial Distribution Analysis from a Thickness Study Using Liquid Crystal Targets

NASA Astrophysics Data System (ADS)

Willis, Christopher; Poole, Patrick; Schumacher, Douglas; Freeman, Richard; van Woerkom, Linn

2016-10-01

Laser-accelerated ions from thin targets have been widely studied for applications including secondary radiation sources and cancer therapy, with recent studies trending towards thinner targets which can provide improved ion energies and yields. Here we discuss results from an experiment on the Scarlet laser at OSU using variable thickness liquid crystal targets. On this experiment, the spatial and spectral distributions of accelerated ions were measured along target normal and laser axes at varying thicknesses from 150nm to 2000nm at a laser intensity of 1 ×1020W /cm2 . Maximum ion energy was observed for targets in the 600 - 800nm thickness range, with proton energies reaching 24MeV . The ions were further characterized using radiochromic film, revealing an unusual spatial distribution on many laser shots. Here, the peak ion yield falls in an annular ring surrounding the target normal, with an increasing divergence angle as a function of ion energy. Details of these spatial and spectral ion distributions will be presented, including spectral deconvolution of the RCF data, revealing additional trends in the accelerated ion distributions. Supported by the DARPA PULSE program through a Grant from AMRDEC, and by the NNSA under contract DE-NA0001976.

Conditional sampling technique to test the applicability of the Taylor hypothesis for the large-scale coherent structures

NASA Technical Reports Server (NTRS)

Hussain, A. K. M. F.

1980-01-01

Comparisons of the distributions of large scale structures in turbulent flow with distributions based on time dependent signals from stationary probes and the Taylor hypothesis are presented. The study investigated an area in the near field of a 7.62 cm circular air jet at a Re of 32,000, specifically having coherent structures through small-amplitude controlled excitation and stable vortex pairing in the jet column mode. Hot-wire and X-wire anemometry were employed to establish phase averaged spatial distributions of longitudinal and lateral velocities, coherent Reynolds stress and vorticity, background turbulent intensities, streamlines and pseudo-stream functions. The Taylor hypothesis was used to calculate spatial distributions of the phase-averaged properties, with results indicating that the usage of the local time-average velocity or streamwise velocity produces large distortions.

Photon event distribution sampling: an image formation technique for scanning microscopes that permits tracking of sub-diffraction particles with high spatial and temporal resolutions.

PubMed

Larkin, J D; Publicover, N G; Sutko, J L

2011-01-01

In photon event distribution sampling, an image formation technique for scanning microscopes, the maximum likelihood position of origin of each detected photon is acquired as a data set rather than binning photons in pixels. Subsequently, an intensity-related probability density function describing the uncertainty associated with the photon position measurement is applied to each position and individual photon intensity distributions are summed to form an image. Compared to pixel-based images, photon event distribution sampling images exhibit increased signal-to-noise and comparable spatial resolution. Photon event distribution sampling is superior to pixel-based image formation in recognizing the presence of structured (non-random) photon distributions at low photon counts and permits use of non-raster scanning patterns. A photon event distribution sampling based method for localizing single particles derived from a multi-variate normal distribution is more precise than statistical (Gaussian) fitting to pixel-based images. Using the multi-variate normal distribution method, non-raster scanning and a typical confocal microscope, localizations with 8 nm precision were achieved at 10 ms sampling rates with acquisition of ~200 photons per frame. Single nanometre precision was obtained with a greater number of photons per frame. In summary, photon event distribution sampling provides an efficient way to form images when low numbers of photons are involved and permits particle tracking with confocal point-scanning microscopes with nanometre precision deep within specimens. © 2010 The Authors Journal of Microscopy © 2010 The Royal Microscopical Society.

Temporal and spatial characteristics of extreme precipitation events in the Midwest of Jilin Province based on multifractal detrended fluctuation analysis method and copula functions

NASA Astrophysics Data System (ADS)

Guo, Enliang; Zhang, Jiquan; Si, Ha; Dong, Zhenhua; Cao, Tiehua; Lan, Wu

2017-10-01

Environmental changes have brought about significant changes and challenges to water resources and management in the world; these include increasing climate variability, land use change, intensive agriculture, and rapid urbanization and industrial development, especially much more frequency extreme precipitation events. All of which greatly affect water resource and the development of social economy. In this study, we take extreme precipitation events in the Midwest of Jilin Province as an example; daily precipitation data during 1960-2014 are used. The threshold of extreme precipitation events is defined by multifractal detrended fluctuation analysis (MF-DFA) method. Extreme precipitation (EP), extreme precipitation ratio (EPR), and intensity of extreme precipitation (EPI) are selected as the extreme precipitation indicators, and then the Kolmogorov-Smirnov (K-S) test is employed to determine the optimal probability distribution function of extreme precipitation indicators. On this basis, copulas connect nonparametric estimation method and the Akaike Information Criterion (AIC) method is adopted to determine the bivariate copula function. Finally, we analyze the characteristics of single variable extremum and bivariate joint probability distribution of the extreme precipitation events. The results show that the threshold of extreme precipitation events in semi-arid areas is far less than that in subhumid areas. The extreme precipitation frequency shows a significant decline while the extreme precipitation intensity shows a trend of growth; there are significant differences in spatiotemporal of extreme precipitation events. The spatial variation trend of the joint return period gets shorter from the west to the east. The spatial distribution of co-occurrence return period takes on contrary changes and it is longer than the joint return period.

An approach to estimate spatial distribution of analyte within cells using spectrally-resolved fluorescence microscopy.

PubMed

Sharma, Dharmendar Kumar; Irfanullah, Mir; Basu, Santanu Kumar; Madhu, Sheri; De, Suman; Jadhav, Sameer; Ravikanth, Mangalampalli; Chowdhury, Arindam

2017-01-18

While fluorescence microscopy has become an essential tool amongst chemists and biologists for the detection of various analyte within cellular environments, non-uniform spatial distribution of sensors within cells often restricts extraction of reliable information on relative abundance of analytes in different subcellular regions. As an alternative to existing sensing methodologies such as ratiometric or FRET imaging, where relative proportion of analyte with respect to the sensor can be obtained within cells, we propose a methodology using spectrally-resolved fluorescence microscopy, via which both the relative abundance of sensor as well as their relative proportion with respect to the analyte can be simultaneously extracted for local subcellular regions. This method is exemplified using a BODIPY sensor, capable of detecting mercury ions within cellular environments, characterized by spectral blue-shift and concurrent enhancement of emission intensity. Spectral emission envelopes collected from sub-microscopic regions allowed us to compare the shift in transition energies as well as integrated emission intensities within various intracellular regions. Construction of a 2D scatter plot using spectral shifts and emission intensities, which depend on the relative amount of analyte with respect to sensor and the approximate local amounts of the probe, respectively, enabled qualitative extraction of relative abundance of analyte in various local regions within a single cell as well as amongst different cells. Although the comparisons remain semi-quantitative, this approach involving analysis of multiple spectral parameters opens up an alternative way to extract spatial distribution of analyte in heterogeneous systems. The proposed method would be especially relevant for fluorescent probes that undergo relatively nominal shift in transition energies compared to their emission bandwidths, which often restricts their usage for quantitative ratiometric imaging in cellular media due to strong cross-talk between energetically separated detection channels.

An approach to estimate spatial distribution of analyte within cells using spectrally-resolved fluorescence microscopy

NASA Astrophysics Data System (ADS)

Sharma, Dharmendar Kumar; Irfanullah, Mir; Basu, Santanu Kumar; Madhu, Sheri; De, Suman; Jadhav, Sameer; Ravikanth, Mangalampalli; Chowdhury, Arindam

2017-03-01

While fluorescence microscopy has become an essential tool amongst chemists and biologists for the detection of various analyte within cellular environments, non-uniform spatial distribution of sensors within cells often restricts extraction of reliable information on relative abundance of analytes in different subcellular regions. As an alternative to existing sensing methodologies such as ratiometric or FRET imaging, where relative proportion of analyte with respect to the sensor can be obtained within cells, we propose a methodology using spectrally-resolved fluorescence microscopy, via which both the relative abundance of sensor as well as their relative proportion with respect to the analyte can be simultaneously extracted for local subcellular regions. This method is exemplified using a BODIPY sensor, capable of detecting mercury ions within cellular environments, characterized by spectral blue-shift and concurrent enhancement of emission intensity. Spectral emission envelopes collected from sub-microscopic regions allowed us to compare the shift in transition energies as well as integrated emission intensities within various intracellular regions. Construction of a 2D scatter plot using spectral shifts and emission intensities, which depend on the relative amount of analyte with respect to sensor and the approximate local amounts of the probe, respectively, enabled qualitative extraction of relative abundance of analyte in various local regions within a single cell as well as amongst different cells. Although the comparisons remain semi-quantitative, this approach involving analysis of multiple spectral parameters opens up an alternative way to extract spatial distribution of analyte in heterogeneous systems. The proposed method would be especially relevant for fluorescent probes that undergo relatively nominal shift in transition energies compared to their emission bandwidths, which often restricts their usage for quantitative ratiometric imaging in cellular media due to strong cross-talk between energetically separated detection channels. Dedicated to Professor Kankan Bhattacharyya.

Sonochemiluminescence observation of lipid- and polymer-shelled ultrasound contrast agents in 1.2 MHz focused ultrasound field.

PubMed

Qiao, Yangzi; Cao, Hua; Zhang, Shusheng; Yin, Hui; Wan, Mingxi

2013-01-01

Ultrasound contrast agents (UCAs) are frequently added into the focused ultrasound field as cavitation nuclei to enhance the therapeutic efficiency. Since their presence will distort the pressure field and make the process unpredictable, comprehension of their behaviors especially the active zone spatial distribution is an important part of better monitoring and using of UCAs. As shell materials can strongly alter the acoustic behavior of UCAs, two different shells coated UCAs, lipid-shelled and polymer-shelled UCAs, in a 1.2 MHz focused ultrasound field were studied by the Sonochemiluminescence (SCL) method and compared. The SCL spatial distribution of lipid-shelled group differed from that of polymer-shelled group. The shell material and the character of focused ultrasound field work together to the SCL distribution, causing the lipid-shelled group to have a maximum SCL intensity in pre-focal region at lower input power than that of polymer-shelled group, and a brighter SCL intensity in post-focal region at high input power. The SCL inactive area of these two groups both increased with the input power. The general behavior of the UCAs can be studied by both the average SCL intensity and the backscatter signals. As polymer-shelled UCAs are more resistant to acoustic pressure, they had a higher destruction power and showed less reactivation than lipid-shelled ones. Copyright © 2012 Elsevier B.V. All rights reserved.

System for obtaining smooth laser beams where intensity variations are reduced by spectral dispersion of the laser light (SSD)

DOEpatents

Skupsky, S.; Kessler, T.J.; Short, R.W.; Craxton, S.; Letzring, S.A.; Soures, J.

1991-09-10

In an SSD (smoothing by spectral dispersion) system which reduces the time-averaged spatial variations in intensity of the laser light to provide uniform illumination of a laser fusion target, an electro-optic phase modulator through which a laser beam passes produces a broadband output beam by imposing a frequency modulated bandwidth on the laser beam. A grating provides spatial and angular spectral dispersion of the beam. Due to the phase modulation, the frequencies (''colors'') cycle across the beam. The dispersed beam may be amplified and frequency converted (e.g., tripled) in a plurality of beam lines. A distributed phase plate (DPP) in each line is irradiated by the spectrally dispersed beam and the beam is focused on the target where a smooth (uniform intensity) pattern is produced. The color cycling enhances smoothing and the use of a frequency modulated laser pulse prevents the formation of high intensity spikes which could damage the laser medium in the power amplifiers. 8 figures.

System for obtaining smooth laser beams where intensity variations are reduced by spectral dispersion of the laser light (SSD)

DOEpatents

Skupsky, Stanley; Kessler, Terrance J.; Short, Robert W.; Craxton, Stephen; Letzring, Samuel A.; Soures, John

1991-01-01

In an SSD (smoothing by spectral dispersion) system which reduces the time-averaged spatial variations in intensity of the laser light to provide uniform illumination of a laser fusion target, an electro-optic phase modulator through which a laser beam passes produces a broadband output beam by imposing a frequency modulated bandwidth on the laser beam. A grating provides spatial and angular spectral dispersion of the beam. Due to the phase modulation, the frequencies ("colors") cycle across the beam. The dispersed beam may be amplified and frequency converted (e.g., tripled) in a plurality of beam lines. A distributed phase plate (DPP) in each line is irradiated by the spectrally dispersed beam and the beam is focused on the target where a smooth (uniform intensity) pattern is produced. The color cycling enhances smoothing and the use of a frequency modulated laser pulse prevents the formation of high intensity spikes which could damage the laser medium in the power amplifiers.

Separating twin images and locating the center of a microparticle in dense suspensions using correlations among reconstructed fields of two parallel holograms.

PubMed

Ling, Hangjian; Katz, Joseph

2014-09-20

This paper deals with two issues affecting the application of digital holographic microscopy (DHM) for measuring the spatial distribution of particles in a dense suspension, namely discriminating between real and virtual images and accurate detection of the particle center. Previous methods to separate real and virtual fields have involved applications of multiple phase-shifted holograms, combining reconstructed fields of multiple axially displaced holograms, and analysis of intensity distributions of weakly scattering objects. Here, we introduce a simple approach based on simultaneously recording two in-line holograms, whose planes are separated by a short distance from each other. This distance is chosen to be longer than the elongated trace of the particle. During reconstruction, the real images overlap, whereas the virtual images are displaced by twice the distance between hologram planes. Data analysis is based on correlating the spatial intensity distributions of the two reconstructed fields to measure displacement between traces. This method has been implemented for both synthetic particles and a dense suspension of 2 μm particles. The correlation analysis readily discriminates between real and virtual images of a sample containing more than 1300 particles. Consequently, we can now implement DHM for three-dimensional tracking of particles when the hologram plane is located inside the sample volume. Spatial correlations within the same reconstructed field are also used to improve the detection of the axial location of the particle center, extending previously introduced procedures to suspensions of microscopic particles. For each cross section within a particle trace, we sum the correlations among intensity distributions in all planes located symmetrically on both sides of the section. This cumulative correlation has a sharp peak at the particle center. Using both synthetic and recorded particle fields, we show that the uncertainty in localizing the axial location of the center is reduced to about one particle's diameter.

Epistemic uncertainty in the location and magnitude of earthquakes in Italy from Macroseismic data

USGS Publications Warehouse

Bakun, W.H.; Gomez, Capera A.; Stucchi, M.

2011-01-01

Three independent techniques (Bakun and Wentworth, 1997; Boxer from Gasperini et al., 1999; and Macroseismic Estimation of Earthquake Parameters [MEEP; see Data and Resources section, deliverable D3] from R.M.W. Musson and M.J. Jimenez) have been proposed for estimating an earthquake location and magnitude from intensity data alone. The locations and magnitudes obtained for a given set of intensity data are almost always different, and no one technique is consistently best at matching instrumental locations and magnitudes of recent well-recorded earthquakes in Italy. Rather than attempting to select one of the three solutions as best, we use all three techniques to estimate the location and the magnitude and the epistemic uncertainties among them. The estimates are calculated using bootstrap resampled data sets with Monte Carlo sampling of a decision tree. The decision-tree branch weights are based on goodness-of-fit measures of location and magnitude for recent earthquakes. The location estimates are based on the spatial distribution of locations calculated from the bootstrap resampled data. The preferred source location is the locus of the maximum bootstrap location spatial density. The location uncertainty is obtained from contours of the bootstrap spatial density: 68% of the bootstrap locations are within the 68% confidence region, and so on. For large earthquakes, our preferred location is not associated with the epicenter but with a location on the extended rupture surface. For small earthquakes, the epicenters are generally consistent with the location uncertainties inferred from the intensity data if an epicenter inaccuracy of 2-3 km is allowed. The preferred magnitude is the median of the distribution of bootstrap magnitudes. As with location uncertainties, the uncertainties in magnitude are obtained from the distribution of bootstrap magnitudes: the bounds of the 68% uncertainty range enclose 68% of the bootstrap magnitudes, and so on. The instrumental magnitudes for large and small earthquakes are generally consistent with the confidence intervals inferred from the distribution of bootstrap resampled magnitudes.

Extreme flood event analysis in Indonesia based on rainfall intensity and recharge capacity

NASA Astrophysics Data System (ADS)

Narulita, Ida; Ningrum, Widya

2018-02-01

Indonesia is very vulnerable to flood disaster because it has high rainfall events throughout the year. Flood is categorized as the most important hazard disaster because it is causing social, economic and human losses. The purpose of this study is to analyze extreme flood event based on satellite rainfall dataset to understand the rainfall characteristic (rainfall intensity, rainfall pattern, etc.) that happened before flood disaster in the area for monsoonal, equatorial and local rainfall types. Recharge capacity will be analyzed using land cover and soil distribution. The data used in this study are CHIRPS rainfall satellite data on 0.05 ° spatial resolution and daily temporal resolution, and GSMap satellite rainfall dataset operated by JAXA on 1-hour temporal resolution and 0.1 ° spatial resolution, land use and soil distribution map for recharge capacity analysis. The rainfall characteristic before flooding, and recharge capacity analysis are expected to become the important information for flood mitigation in Indonesia.

The use of distributed temperature sensing technology for monitoring wildland fire intensity and distribution.

NASA Astrophysics Data System (ADS)

Ochoa, C. G.; Cram, D.; Hatch, C. E.; Tyler, S. W.

2014-12-01

Distributed temperature sensing (DTS) technology offers a viable alternative for accurately measuring wildland fire intensity and distribution in real time applications. We conducted an experiment to test the use of DTS as an alternative technology to monitor prescribed fire temperatures in real time and across a broad spatial scale. The custom fiber-optic cable consisted of three fiber optic lines buffered by polyamide, copper, and polyvinyl chloride, respectively, each armored in a stainless steel tube backfilled with Nitrogen gas. The 150 m long cable was deployed in three different 20 by 26 m experimental plots of short-grass rangeland in central New Mexico. Cable was arranged to maximize coverage of the experimental plots and allow cross-comparison between two main parallel straight-line sections approximately 8 m apart. A DTS system recorded fire temperatures every three seconds and integrated every one meter. A series of five thermocouples attached to a datalogger were placed at selected locations along the cable and also recorded temperature data every three seconds on each fiber. Results indicate that in general there is good agreement between thermocouple-measured and DTS-measured temperatures. A close match in temperature between DTS and thermocouples was particularly observed during the rising limb but not so much during the decline. The metal armoring of the fiber-optic cable remained hot longer than the thermocouples after the flames had passed. The relatively short-duration, high-intensity, prescribed burn fire in each plot resulted in temperatures reaching up to 450 degrees Celsius. In addition, DTS data allow for illustration of the irregular nature of flame speed and travel path across the rangeland grasses, a phenomenon that was impossible to quantify without the use of this tool. This study adds to the understanding of using DTS as a new alternative tool for better characterizing wildland fire intensity, distribution and travel patterns, and establishes the baseline for expanding these test plot results to larger spatial scales.

Frequency Distribution of Seismic Intensity in Japan between 1950 and 2009

NASA Astrophysics Data System (ADS)

Kato, M.; Kohayakawa, Y.

2012-12-01

JMA Seismic Intensity is an index of seismic ground motion which is frequently used and reported in the media. While it is always difficult to represent complex ground motion with one index, the fact that it is widely accepted in the society makes the use of JMA Seismic Intensity preferable when seismologists communicate with the public and discuss hazard assessment and risk management. With the introduction on JMA Instrumental Intensity in 1996, the number of seismic intensity observation sites has substantially increased and the spatial coverage has improved vastly. Together with a long history of non-instrumental intensity records, the intensity data represent some aspects of the seismic ground motion in Japan. We investigate characteristics of seismic ground motion between 1950 and 2009 utilizing JMA Seismic Intensity Database. Specifically we are interested in the frequency distribution of intensity recordings. Observations of large intensity is rare compared to those of small intensity, and previous studies such as Ikegami [1961] demonstrated that frequency distribution of observed intensity obeys an exponential law, which is equivalent to the Ishimoto-Iida law [Ishimoto & Iida, 1939]. Such behavior could be used to empirically construct probabilistic seismic hazard maps [e.g., Kawasumi, 1951]. For the recent instrumental intensity data as well as pre-instrumental data, we are able to confirm that Ishimoto-Iida law explains the observation. Exponents of the Ishimoto-Iida law, or slope of the exponential law in the semi-log plot, is approximately 0.5. At stations with long recordings, there is no apparent difference between pre-instrumental and instrumental intensities when Ishimoto-Iida law is used as a measure. Numbers of average intensity reports per year and exponents of the frequency distribution curve vary regionally and local seismicity is apparently the controlling factor. The observed numbers of large intensity is slightly less than extrapolated and predicted from those of small intensity assuming the exponential relation.

Very exceptional cases of VLF/LF ionospheric perturbations for deep oceanic earthquakes offshore the Japan island

NASA Astrophysics Data System (ADS)

Yamaguchi, Hiroki; Hayakawa, Masashi

2015-12-01

It is so far believed that ionospheric perturbations as detected by subionospheric VLF/LF (very low frequency/low frequency) propagation, are generated above and around the earthquake (EQ) epicenter. This paper presents very rare cases, which are in complete contrast to the above fact. We have found that in extremely rare cases when EQs happened (i) in the Pacific Ocean or (ii) offshore the Soya cape (Hokkaido) both with very large depths (300-400 km), corresponding ionospheric perturbations take place far away from the EQ epicenter and above the regions with considerable seismic intensity at the time of each EQ. Two EQs happened in the Torishima area of Izu islands (magnitude ∼7 and depth ∼400 km), and corresponding seismic intensity was observed in the Tokyo and Ibaraki districts. Our VLF data have indicated that the ionospheric perturbation takes place over such regions with high seismic intensity. Another group is two EQs (magnitude ∼5) offshore the Soya cape of Hokkaido, and the spatial distribution of seismic intensity at the time of each EQ is just around Aomori prefecture. VLF data have indicated the ionospheric perturbations taken place over the same Aomori area, which is in complete coincidence with the spatial distribution of seismic intensity. As a conclusion, these exceptional examples are, in principle, very similar to the concept of 'selectivity' (or sensitive zone) of geoelectric measurement by the Greek group, and we try to interpret these cases in the context of lithosphere-atmosphere-ionosphere coupling.

Spatial characterization of innervation zones under electrically elicited M-wave.

PubMed

Zhang, C; Peng, Y; Li, S; Zhou, P; Munoz, A; Tang, D; Zhang, Y

2016-08-01

The three dimensional (3D) innervation zone (IZ) imaging approach (3DIZI) has been developed in our group to localize the IZ of a particular motor unit (MU) from its motor unit action potentials decomposed from high-density surface electromyography (EMG) recordings. In this study, the developed 3DIZI approach was combined with electrical stimulation to investigate global distributions of IZs in muscles from electrically elicited M-wave recordings. Electrical stimulations were applied to the musculocutaneous nerve to activate supramaximal muscle response of the biceps brachii in one healthy subject, and high-density (128 channels) surface EMG signals of the biceps brachii muscles were recorded. The 3DIZI approach was then employed to image the IZ distribution of IZs in the 3D space of the biceps brachii. The performance of the M-wave based 3DIZI approach was evaluated with different stimulation intensities. Results show that the reconstructed IZs under supramaximal stimulation are spatially distributed in the center region of muscle belly which is consistent with previous studies. With sub-maximal stimulation intensity, the imaged IZ centers became more proximally and deeply located. The proposed M-wave based 3DIZI approach demonstrated its capability of imaging global distribution of IZs in muscles, which provide valuable information for clinical applications such as guiding botulinum toxin injection in treating muscle spasticity.

Spatial distribution of Dactylogyrus wunderi Bychowsky on gills of Abramis brama orientalis Berg (Leuciscinae) in Irtysh River, China

NASA Astrophysics Data System (ADS)

Hao, Cuilan; Yue, Cheng; Yao, Weijian; Yin, Jianguo; Jiao, Li; Zhu, Mengying; Jia, Shu'an; Wang, Na; Wang, Xin

2013-09-01

The spatial distribution of the monogenean Dactylogyrus wunderi Bychowsky, 1931 on the gill filaments of the bream Abramis brama orientalis Berg (Leuciscinae) inhabiting the Irtysh River of Xinjiang, China was investigated from June to July 2012. D. wunderi was identified by sequencing a fragment of its ITS rDNA region. Sixty-five fish were examined, with 55% testing positive for monogenean infection. The prevalence of the parasite in the left and right gill arches was 46% and 48%, respectively. In fish with a large body length, the prevalence of the parasite and the infection intensity did not significantly differ between the right and left gill arches but both were slightly higher in the former. Among the three size groups of fish (small, medium and large) the prevalence and the intensity of infection were lowest in fish with small body lengths. The distribution of the monogenean population in the host gills showed an aggregate distribution, with little change in the degree of aggregation, suggesting that most hosts were either not or only slightly infected by D. wunderi and that the parasite infected only a few hosts. In addition, differences in D. wunderi infections between gill arches of A. brama orientalis were not significant ( P>0.05).

The effects of spatial sampling choices on MR temperature measurements.

PubMed

Todd, Nick; Vyas, Urvi; de Bever, Josh; Payne, Allison; Parker, Dennis L

2011-02-01

The purpose of this article is to quantify the effects that spatial sampling parameters have on the accuracy of magnetic resonance temperature measurements during high intensity focused ultrasound treatments. Spatial resolution and position of the sampling grid were considered using experimental and simulated data for two different types of high intensity focused ultrasound heating trajectories (a single point and a 4-mm circle) with maximum measured temperature and thermal dose volume as the metrics. It is demonstrated that measurement accuracy is related to the curvature of the temperature distribution, where regions with larger spatial second derivatives require higher resolution. The location of the sampling grid relative temperature distribution has a significant effect on the measured values. When imaging at 1.0 × 1.0 × 3.0 mm(3) resolution, the measured values for maximum temperature and volume dosed to 240 cumulative equivalent minutes (CEM) or greater varied by 17% and 33%, respectively, for the single-point heating case, and by 5% and 18%, respectively, for the 4-mm circle heating case. Accurate measurement of the maximum temperature required imaging at 1.0 × 1.0 × 3.0 mm(3) resolution for the single-point heating case and 2.0 × 2.0 × 5.0 mm(3) resolution for the 4-mm circle heating case. Copyright © 2010 Wiley-Liss, Inc.

A tesselation-based model for intensity estimation and laser plasma interactions calculations in three dimensions

NASA Astrophysics Data System (ADS)

Colaïtis, A.; Chapman, T.; Strozzi, D.; Divol, L.; Michel, P.

2018-03-01

A three-dimensional laser propagation model for computation of laser-plasma interactions is presented. It is focused on indirect drive geometries in inertial confinement fusion and formulated for use at large temporal and spatial scales. A modified tesselation-based estimator and a relaxation scheme are used to estimate the intensity distribution in plasma from geometrical optics rays. Comparisons with reference solutions show that this approach is well-suited to reproduce realistic 3D intensity field distributions of beams smoothed by phase plates. It is shown that the method requires a reduced number of rays compared to traditional rigid-scale intensity estimation. Using this field estimator, we have implemented laser refraction, inverse-bremsstrahlung absorption, and steady-state crossed-beam energy transfer with a linear kinetic model in the numerical code Vampire. Probe beam amplification and laser spot shapes are compared with experimental results and pf3d paraxial simulations. These results are promising for the efficient and accurate computation of laser intensity distributions in holhraums, which is of importance for determining the capsule implosion shape and risks of laser-plasma instabilities such as hot electron generation and backscatter in multi-beam configurations.

Monitoring Method of Cow Anthrax Based on Gis and Spatial Statistical Analysis

NASA Astrophysics Data System (ADS)

Li, Lin; Yang, Yong; Wang, Hongbin; Dong, Jing; Zhao, Yujun; He, Jianbin; Fan, Honggang

Geographic information system (GIS) is a computer application system, which possesses the ability of manipulating spatial information and has been used in many fields related with the spatial information management. Many methods and models have been established for analyzing animal diseases distribution models and temporal-spatial transmission models. Great benefits have been gained from the application of GIS in animal disease epidemiology. GIS is now a very important tool in animal disease epidemiological research. Spatial analysis function of GIS can be widened and strengthened by using spatial statistical analysis, allowing for the deeper exploration, analysis, manipulation and interpretation of spatial pattern and spatial correlation of the animal disease. In this paper, we analyzed the cow anthrax spatial distribution characteristics in the target district A (due to the secret of epidemic data we call it district A) based on the established GIS of the cow anthrax in this district in combination of spatial statistical analysis and GIS. The Cow anthrax is biogeochemical disease, and its geographical distribution is related closely to the environmental factors of habitats and has some spatial characteristics, and therefore the correct analysis of the spatial distribution of anthrax cow for monitoring and the prevention and control of anthrax has a very important role. However, the application of classic statistical methods in some areas is very difficult because of the pastoral nomadic context. The high mobility of livestock and the lack of enough suitable sampling for the some of the difficulties in monitoring currently make it nearly impossible to apply rigorous random sampling methods. It is thus necessary to develop an alternative sampling method, which could overcome the lack of sampling and meet the requirements for randomness. The GIS computer application software ArcGIS9.1 was used to overcome the lack of data of sampling sites.Using ArcGIS 9.1 and GEODA to analyze the cow anthrax spatial distribution of district A. we gained some conclusions about cow anthrax' density: (1) there is a spatial clustering model. (2) there is an intensely spatial autocorrelation. We established a prediction model to estimate the anthrax distribution based on the spatial characteristic of the density of cow anthrax. Comparing with the true distribution, the prediction model has a well coincidence and is feasible to the application. The method using a GIS tool facilitates can be implemented significantly in the cow anthrax monitoring and investigation, and the space statistics - related prediction model provides a fundamental use for other study on space-related animal diseases.

Calculation of x-ray scattering patterns from nanocrystals at high x-ray intensity

PubMed Central

Abdullah, Malik Muhammad; Jurek, Zoltan; Son, Sang-Kil; Santra, Robin

2016-01-01

We present a generalized method to describe the x-ray scattering intensity of the Bragg spots in a diffraction pattern from nanocrystals exposed to intense x-ray pulses. Our method involves the subdivision of a crystal into smaller units. In order to calculate the dynamics within every unit, we employ a Monte-Carlo-molecular dynamics-ab-initio hybrid framework using real space periodic boundary conditions. By combining all the units, we simulate the diffraction pattern of a crystal larger than the transverse x-ray beam profile, a situation commonly encountered in femtosecond nanocrystallography experiments with focused x-ray free-electron laser radiation. Radiation damage is not spatially uniform and depends on the fluence associated with each specific region inside the crystal. To investigate the effects of uniform and non-uniform fluence distribution, we have used two different spatial beam profiles, Gaussian and flattop. PMID:27478859

Generation of dark hollow femtosecond pulsed beam by phase-only liquid crystal spatial light modulator.

PubMed

Nie, Yongming; Ma, Haotong; Li, Xiujian; Hu, Wenhua; Yang, Jiankun

2011-07-20

Based on the refractive laser beam shaping system, the dark hollow femtosecond pulse beam shaping technique with a phase-only liquid crystal spatial light modulator (LC-SLM) is demonstrated. The phase distribution of the LC-SLM is derived by the energy conservation and constant optical path principle. The effects of the shaping system on the temporal properties, including spectral phase distribution and bandwidth of the femtosecond pulse, are analyzed in detail. Experimental results show that the hollow intensity distribution of the output pulsed beam can be maintained much at more than 1200 mm. The spectral phase of the pulse is changed, and the pulse width is expanded from 199 to 230 fs, which is caused by the spatial-temporal coupling effect. The coupling effect mainly depends on the phase-only LC-SLM itself, not on its loaded phase distribution. The experimental results indicate that the proposed shaping setup can generate a dark hollow femtosecond pulsed beam effectively, because the temporal Gaussian waveform is unchanged. © 2011 Optical Society of America

Multiscale responses of soil stability and invasive plants to removal of non-native grazers from an arid conservation reserve

USGS Publications Warehouse

Beever, E.A.; Huso, M.; Pyke, D.A.

2006-01-01

Disturbances and ecosystem recovery from disturbance both involve numerous processes that operate on multiple spatial and temporal scales. Few studies have investigated how gradients of disturbance intensity and ecosystem responses are distributed across multiple spatial resolutions and also how this relationship changes through time during recovery. We investigated how cover of non-native species and soil-aggregate stability (a measure of vulnerability to erosion by water) in surface and subsurface soils varied spatially during grazing by burros and cattle and whether patterns in these variables changed after grazer removal from Mojave National Preserve, California, USA. We compared distance from water and number of ungulate defecations - metrics of longer-term and recent grazing intensity, respectively, - as predictors of our response variables. We used information-theoretic analyses to compare hierarchical linear models that accounted for important covariates and allowed for interannual variation in the disturbance-response relationship at local and landscape scales. Soil stability was greater under perennial vegetation than in bare interspaces, and surface soil stability decreased with increasing numbers of ungulate defecations. Stability of surface samples was more affected by time since removal of grazers than was stability of subsurface samples, and subsurface soil stability in bare spaces was not related to grazing intensity, time since removal, or any of our other predictors. In the high rainfall year (2003) after cattle had been removed for 1-2 years, cover of all non-native plants averaged nine times higher than in the low-rainfall year (2002). Given the heterogeneity in distribution of large-herbivore impacts that we observed at several resolutions, hierarchical analyses provided a more complete understanding of the spatial and temporal complexities of disturbance and recovery processes in arid ecosystems. ?? 2006 Blackwell Publishing Ltd.

Multi-scale responses of soil stability and invasive plants to removal of non-native grazers from an arid conservation reserve

USGS Publications Warehouse

Beever, Erik A.; Huso, Manuela M. P.; Pyke, David A.

2006-01-01

Disturbances and ecosystem recovery from disturbance both involve numerous processes that operate on multiple spatial and temporal scales. Few studies have investigated how gradients of disturbance intensity and ecosystem responses are distributed across multiple spatial resolutions and also how this relationship changes through time during recovery. We investigated how cover of non-native species and soil-aggregate stability (a measure of vulnerability to erosion by water) in surface and subsurface soils varied spatially during grazing by burros and cattle and whether patterns in these variables changed after grazer removal from Mojave National Preserve, California, USA. We compared distance from water and number of ungulate defecations — metrics of longer-term and recent grazing intensity, respectively, — as predictors of our response variables. We used information-theoretic analyses to compare hierarchical linear models that accounted for important covariates and allowed for interannual variation in the disturbance–response relationship at local and landscape scales. Soil stability was greater under perennial vegetation than in bare interspaces, and surface soil stability decreased with increasing numbers of ungulate defecations. Stability of surface samples was more affected by time since removal of grazers than was stability of subsurface samples, and subsurface soil stability in bare spaces was not related to grazing intensity, time since removal, or any of our other predictors. In the high rainfall year (2003) after cattle had been removed for 1–2 years, cover of all non-native plants averaged nine times higher than in the low-rainfall year (2002). Given the heterogeneity in distribution of large-herbivore impacts that we observed at several resolutions, hierarchical analyses provided a more complete understanding of the spatial and temporal complexities of disturbance and recovery processes in arid ecosystems.

Imaging of spatial distributions of the millimeter wave intensity by using visible continuum radiation from a discharge in a Cs–Xe mixture. Part I: Review of the method and its fundamentals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gitlin, M. S., E-mail: gitlin@appl.sci-nnov.ru

The first part of the review is presented which is dedicated to the time-resolved method of imaging and measuring the spatial distribution of the intensity of millimeter waves by using visible continuum (VC) emitted by the positive column (PC) of a dc discharge in a mixture of cesium vapor with xenon. The review focuses on the operating principles, fundamentals, and applications of this new technique. The design of the discharge tube and experimental setup used to create a wide homogeneous plasma slab with the help of the Cs–Xe discharge at a gas pressure of 45 Torr are described. The millimeter-wavemore » effects on the plasma slab are studied experimentally. The mechanism of microwave-induced variations in the VC brightness and the causes of violation of the local relation between the VC brightness and the intensity of millimeter waves are discussed. Experiments on the imaging of the field patterns of horn antennas and quasi-optical beams demonstrate that this technique can be used for good-quality imaging of millimeter-wave beams in the entire millimeter-wavelength band. The method has a microsecond temporal resolution and a spatial resolution of about 2 mm. Energy sensitivities of about 10 μJ/cm{sup 2} in the Ka-band and about 200 μJ/cm{sup 2} in the D-band have been demonstrated.« less

Mapping and determinism of soil microbial community distribution across an agricultural landscape

PubMed Central

Constancias, Florentin; Terrat, Sébastien; Saby, Nicolas P A; Horrigue, Walid; Villerd, Jean; Guillemin, Jean-Philippe; Biju-Duval, Luc; Nowak, Virginie; Dequiedt, Samuel; Ranjard, Lionel; Chemidlin Prévost-Bouré, Nicolas

2015-01-01

Despite the relevance of landscape, regarding the spatial patterning of microbial communities and the relative influence of environmental parameters versus human activities, few investigations have been conducted at this scale. Here, we used a systematic grid to characterize the distribution of soil microbial communities at 278 sites across a monitored agricultural landscape of 13 km². Molecular microbial biomass was estimated by soil DNA recovery and bacterial diversity by 16S rRNA gene pyrosequencing. Geostatistics provided the first maps of microbial community at this scale and revealed a heterogeneous but spatially structured distribution of microbial biomass and diversity with patches of several hundreds of meters. Variance partitioning revealed that both microbial abundance and bacterial diversity distribution were highly dependent of soil properties and land use (total variance explained ranged between 55% and 78%). Microbial biomass and bacterial richness distributions were mainly explained by soil pH and texture whereas bacterial evenness distribution was mainly related to land management. Bacterial diversity (richness, evenness, and Shannon index) was positively influenced by cropping intensity and especially by soil tillage, resulting in spots of low microbial diversity in soils under forest management. Spatial descriptors also explained a small but significant portion of the microbial distribution suggesting that landscape configuration also shapes microbial biomass and bacterial diversity. PMID:25833770

Apodization of two-dimensional pupils with aberrations

NASA Astrophysics Data System (ADS)

Reddy, Andra Naresh Kumar; Hashemi, Mahdieh; Khonina, Svetlana Nikolaevna

2018-06-01

The technique proposed to enhance the resolution of the point spread function (PSF) of an optical system underneath defocussing and spherical aberrations. The method of approach is based on the amplitude and phase masking in a ring aperture for modifying the light intensity distribution in the Gaussian focal plane (YD = 0) and in the defocussed planes (YD= π and YD= 2π ). The width of the annulus modifies the distribution of the light intensity in the side lobes of the resultant PSF. In the presence of an asymmetry in the phase of the annulus, the Hanning amplitude apodizer [cos(π β ρ )] employed in the pupil function can modify the spatial distribution of light in the maximum defocussed plane ({Y}D = 2π ), results in PSF with improved resolution.

Research and development on the construction of 2D light-driven droplet manipulation platform based on light modulation of TiOPc impedance

NASA Astrophysics Data System (ADS)

Chen, Yi-Chen; Chen, Ho-Tsung; Lee, Chih-Kung

2014-03-01

The newly developed configuration included adopting the photosensitive electrode material TiOPc (titanyl phthalocyanine) to create electrowetting on dielectric (EWOD) mechanism. With this new development, the electric potential on the surface of TiOPc could be on-line real-time changed and defined spatially by illuminating spatially distributed light beam patterns. We tried to control the polarized droplets in our EWOD devices by using different light intensities. The experimental results clearly demonstrated that the relationship of light intensity and electrowetting phenomena can provide us with a feasible platform to construct optofluidic chip with potential autonomous manipulation of samples for point-of-care home medical detection applications.

Influence of sea-land breezes on the tempospatial distribution of atmospheric aerosols over coastal region.

PubMed

Tsai, Hsieh-Hung; Yuan, Chung-Shin; Hung, Chung-Hsuang; Lin, Chitsan; Lin, Yuan-Chung

2011-04-01

The influence of sea-land breezes (SLBs) on the spatial distribution and temporal variation of particulate matter (PM) in the atmosphere was investigated over coastal Taiwan. PM was simultaneously sampled at inland and offshore locations during three intensive sampling periods. The intensive PM sampling protocol was continuously conducted over a 48-hr period. During this time, PM2.5 and PM(2.5-10) (PM with aerodynamic diameters < 2.5 microm and between 2.5 and 10 microm, respectively) were simultaneously measured with dichotomous samplers at four sites (two inland and two offshore sites) and PM10 (PM with aerodynamic diameters < or =10 microm) was measured with beta-ray monitors at these same 4 sites and at 10 sites of the Taiwan Air Quality Monitoring Network. PM sampling on a mobile air quality monitoring boat was further conducted along the coastline to collect offshore PM using a beta-ray monitor and a dichotomous sampler. Data obtained from the inland sites (n=12) and offshore sites (n=2) were applied to plot the PM10 concentration contour using Surfer software. This study also used a three-dimensional meteorological model (Pennsylvania State University/National Center for Atmospheric Research Meteorological Model 5) and the Comprehensive Air Quality Model with Extensions to simulate surface wind fields and spatial distribution of PM10 over the coastal region during the intensive sampling periods. Spatial distribution of PM10 concentration was further used in investigating the influence of SLBs on the transport of PM10 over the coastal region. Field measurement and model simulation results showed that PM10 was transported back and forth across the coastline. In particular, a high PM10 concentration was observed at the inland sites during the day because of sea breezes, whereas a high PM10 concentration was detected offshore at night because of land breezes. This study revealed that the accumulation of PM in the near-ocean region because of SLBs influenced the tempospatial distribution of PM10 over the coastal region.

Spatial mismatch analysis among hotspots of alien plant species, road and railway networks in Germany and Austria

PubMed Central

Morelli, Federico

2017-01-01

Road and railway networks are pervasive elements of all environments, which have expanded intensively over the last century in all European countries. These transportation infrastructures have major impacts on the surrounding landscape, representing a threat to biodiversity. Roadsides and railways may function as corridors for dispersal of alien species in fragmented landscapes. However, only few studies have explored the spread of invasive species in relationship to transport network at large spatial scales. We performed a spatial mismatch analysis, based on a spatially explicit correlation test, to investigate whether alien plant species hotspots in Germany and Austria correspond to areas of high density of roads and railways. We tested this independently of the effects of dominant environments in each spatial unit, in order to focus just on the correlation between occurrence of alien species and density of linear transportation infrastructures. We found a significant spatial association between alien plant species hotspots distribution and roads and railways density in both countries. As expected, anthropogenic landscapes, such as urban areas, harbored more alien plant species, followed by water bodies. However, our findings suggested that the distribution of neobiota is strongest correlated to road/railways density than to land use composition. This study provides new evidence, from a transnational scale, that alien plants can use roadsides and rail networks as colonization corridors. Furthermore, our approach contributes to the understanding on alien plant species distribution at large spatial scale by the combination with spatial modeling procedures. PMID:28829818

PROBING THE IONIZATION STATES OF POLYCYCLIC AROMATIC HYDROCARBONS VIA THE 15–20 μm EMISSION BANDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shannon, M. J.; Stock, D. J.; Peeters, E., E-mail: mshann3@uwo.ca

2015-10-01

We report new correlations between ratios of band intensities of the 15–20 μm emission bands of polycyclic aromatic hydrocarbons (PAHs) in a sample of 57 sources observed with the Spitzer/Infrared Spectrograph. This sample includes Large Magellanic Cloud point sources from the SAGE-Spec survey, nearby galaxies from the Spitzer Infrared Nearby Galaxies Survey survey, two Galactic interstellar medium cirrus sources, and the spectral maps of the Galactic reflection nebulae NGC 2023 and NGC 7023. We find that the 16.4, 17.4, and 17.8 μm band intensities are inter-correlated in all environments. In NGC 2023 and NGC 7023 these bands also correlate withmore » the 11.0 and 12.7 μm band intensities. The 15.8 μm band correlates only with the 15–18 μm plateau and the 11.2 μm emission. We examine the spatial morphology of these bands and introduce radial cuts. We find that these bands can be spatially organized into three sets: the 12.7, 16.4, and 17.8 μm bands; the 11.2, 15.8 μm bands and the 15–18 μm plateau; and the 11.0 and 17.4 μm bands. We also find that the spatial distribution of the 12.7, 16.4, and 17.8 μm bands can be reconstructed by averaging the spatial distributions of the cationic 11.0 μm and neutral 11.2 μm bands. We conclude that the 17.4 μm band is dominated by cations, the 15.8 μm band by neutral species, and the 12.7, 16.4, and 17.8 μm bands by a combination of the two. These results highlight the importance of PAH ionization for spatially differentiating sub-populations by their 15–20 μm emission variability.« less

Interpolating Non-Parametric Distributions of Hourly Rainfall Intensities Using Random Mixing

NASA Astrophysics Data System (ADS)

Mosthaf, Tobias; Bárdossy, András; Hörning, Sebastian

2015-04-01

The correct spatial interpolation of hourly rainfall intensity distributions is of great importance for stochastical rainfall models. Poorly interpolated distributions may lead to over- or underestimation of rainfall and consequently to wrong estimates of following applications, like hydrological or hydraulic models. By analyzing the spatial relation of empirical rainfall distribution functions, a persistent order of the quantile values over a wide range of non-exceedance probabilities is observed. As the order remains similar, the interpolation weights of quantile values for one certain non-exceedance probability can be applied to the other probabilities. This assumption enables the use of kernel smoothed distribution functions for interpolation purposes. Comparing the order of hourly quantile values over different gauges with the order of their daily quantile values for equal probabilities, results in high correlations. The hourly quantile values also show high correlations with elevation. The incorporation of these two covariates into the interpolation is therefore tested. As only positive interpolation weights for the quantile values assure a monotonically increasing distribution function, the use of geostatistical methods like kriging is problematic. Employing kriging with external drift to incorporate secondary information is not applicable. Nonetheless, it would be fruitful to make use of covariates. To overcome this shortcoming, a new random mixing approach of spatial random fields is applied. Within the mixing process hourly quantile values are considered as equality constraints and correlations with elevation values are included as relationship constraints. To profit from the dependence of daily quantile values, distribution functions of daily gauges are used to set up lower equal and greater equal constraints at their locations. In this way the denser daily gauge network can be included in the interpolation of the hourly distribution functions. The applicability of this new interpolation procedure will be shown for around 250 hourly rainfall gauges in the German federal state of Baden-Württemberg. The performance of the random mixing technique within the interpolation is compared to applicable kriging methods. Additionally, the interpolation of kernel smoothed distribution functions is compared with the interpolation of fitted parametric distributions.

Spectral and Spatial UV Sky Radiance Measurements at a Seaside Resort Under Clear Sky and Slightly Overcast Conditions.

PubMed

Sandmann, Henner; Stick, Carsten

2014-01-01

Spatial measurements of the diffusely scattered sky radiance at a seaside resort under clear sky and slightly overcast conditions have been used to calculate the sky radiance distribution across the upper hemisphere. The measurements were done in the summer season when solar UV radiation is highest. The selected wavelengths were 307, 350 and 550 nm representing the UVB, UVA and VIS band. Absolute values of radiance differ considerably between the wavelengths. Normalizing the measured values by use of direct solar radiance made the spatial distributions of unequal sky radiance comparable. The results convey a spatial impression of the different distributions of the radiance at the three wavelengths. Relative scattered radiance intensity is one order of magnitude greater in UVB than in VIS, whereas in UVA lies roughly in between. Under slightly overcast conditions scattered radiance is increased at all three wavelengths by about one order of magnitude. These measurements taken at the seaside underline the importance of diffuse scattered radiance. The effect of shading parts of the sky can be estimated from the distribution of sky radiance. This knowledge might be useful for sun seekers and in the treatment of people staying at the seaside for therapeutic purposes. © 2013 The American Society of Photobiology.

Spatial Distribution and Trends of Waterborne Diseases in Tashkent Province

PubMed Central

Subramanian, Veluswami Saravanan; Cho, Min Jung; Tan, Siwei Zoe; Fayzieva, Dilorom; Sebaly, Christian

2017-01-01

Introduction: The cumulative effect of limited investment in public water systems, inadequate public health infrastructure, and gaps in infectious disease prevention increased the incidence of waterborne diseases in Uzbekistan. The objectives of this study were: (1) to spatially analyze the distribution of the diseases in Tashkent Province, (2) to identify the intensity of spatial trends in the province, (3) to identify urban-rural characteristics of the disease distribution, and (4) to identify the differences in disease incidence between pediatric and adult populations of the province. Methods: Data on four major waterborne diseases and socio-demographics factors were collected in Tashkent Province from 2011 to 2014. Descriptive epidemiological methods and spatial-temporal methods were used to investigate the distribution and trends, and to identify waterborne diseases hotspots and vulnerable population groups in the province. Results: Hepatitis A and enterobiasis had a high incidence in most of Tashkent Province, with higher incidences in the eastern and western districts. Residents of rural areas, including children, were found to be more vulnerable to the waterborne diseases compared to other populations living in the province. Conclusions: This pilot study calls for more scientific investigations of waterborne diseases and their effect on public health in the region, which could facilitate targeted public health interventions in vulnerable regions of Uzbekistan. PMID:29138738

Spatial Distribution and Trends of Waterborne Diseases in Tashkent Province.

PubMed

Subramanian, Veluswami Saravanan; Cho, Min Jung; Tan, Siwei Zoe; Fayzieva, Dilorom; Sebaly, Christian

2017-01-01

The cumulative effect of limited investment in public water systems, inadequate public health infrastructure, and gaps in infectious disease prevention increased the incidence of waterborne diseases in Uzbekistan. The objectives of this study were: (1) to spatially analyze the distribution of the diseases in Tashkent Province, (2) to identify the intensity of spatial trends in the province, (3) to identify urban-rural characteristics of the disease distribution, and (4) to identify the differences in disease incidence between pediatric and adult populations of the province. Data on four major waterborne diseases and socio-demographics factors were collected in Tashkent Province from 2011 to 2014. Descriptive epidemiological methods and spatial-temporal methods were used to investigate the distribution and trends, and to identify waterborne diseases hotspots and vulnerable population groups in the province. Hepatitis A and enterobiasis had a high incidence in most of Tashkent Province, with higher incidences in the eastern and western districts. Residents of rural areas, including children, were found to be more vulnerable to the waterborne diseases compared to other populations living in the province. This pilot study calls for more scientific investigations of waterborne diseases and their effect on public health in the region, which could facilitate targeted public health interventions in vulnerable regions of Uzbekistan.

Efficient multi-objective calibration of a computationally intensive hydrologic model with parallel computing software in Python

USDA-ARS?s Scientific Manuscript database

With enhanced data availability, distributed watershed models for large areas with high spatial and temporal resolution are increasingly used to understand water budgets and examine effects of human activities and climate change/variability on water resources. Developing parallel computing software...

Using VELMA to Quantify and Visualize the Effectiveness of Green Infrastructure Options for Protecting Water Quality

EPA Science Inventory

This webinar describes the use of VELMA, a spatially-distributed ecohydrological model, to identify green infrastructure (GI) best management practices for protecting water quality in intensively managed watersheds. The seminar will include a brief description of VELMA and an ex...

Monitoring of concentrated radiation beam for photovoltaic and thermal solar energy conversion applications.

PubMed

Parretta, Antonio; Privato, Carlo; Nenna, Giuseppe; Antonini, Andrea; Stefancich, Marco

2006-10-20

Methods for evaluating the light intensity distribution on receivers of concentrated solar radiation systems are described. They are based on the use of Lambertian diffusers in place of the illuminated receiver and on the acquisition of the scattered light, in reflection or transmission mode, by a CCD camera. The spatial distribution of intensity radiation is then numerically derived from the recorded images via a proprietary code. The details of the method are presented and a short survey of the main applications of the method in the photovoltaic and thermal solar energy conversion field is proposed. Methods for investigating the Lambertian character of commercial diffusers are also discussed.

Spatial and Temporal Distribution of Multiple Cropping Indices in the North China Plain Using a Long Remote Sensing Data Time Series.

PubMed

Zhao, Yan; Bai, Linyan; Feng, Jianzhong; Lin, Xiaosong; Wang, Li; Xu, Lijun; Ran, Qiyun; Wang, Kui

2016-04-19

Multiple cropping provides China with a very important system of intensive cultivation, and can effectively enhance the efficiency of farmland use while improving regional food production and security. A multiple cropping index (MCI), which represents the intensity of multiple cropping and reflects the effects of climate change on agricultural production and cropping systems, often serves as a useful parameter. Therefore, monitoring the dynamic changes in the MCI of farmland over a large area using remote sensing data is essential. For this purpose, nearly 30 years of MCIs related to dry land in the North China Plain (NCP) were efficiently extracted from remotely sensed leaf area index (LAI) data from the Global LAnd Surface Satellite (GLASS). Next, the characteristics of the spatial-temporal change in MCI were analyzed. First, 2162 typical arable sample sites were selected based on a gridded spatial sampling strategy, and then the LAI information was extracted from the samples. Second, the Savizky-Golay filter was used to smooth the LAI time-series data of the samples, and then the MCIs of the samples were obtained using a second-order difference algorithm. Finally, the geo-statistical Kriging method was employed to map the spatial distribution of the MCIs and to obtain a time-series dataset of the MCIs of dry land over the NCP. The results showed that all of the MCIs in the NCP showed an increasing trend over the entire study period and increased most rapidly from 1982 to 2002. Spatially, MCIs decreased from south to north; also, high MCIs were mainly concentrated in the relatively flat areas. In addition, the partial spatial changes of MCIs had clear geographical characteristics, with the largest change in Henan Province.

Spatial and Temporal Distribution of Multiple Cropping Indices in the North China Plain Using a Long Remote Sensing Data Time Series

PubMed Central

Zhao, Yan; Bai, Linyan; Feng, Jianzhong; Lin, Xiaosong; Wang, Li; Xu, Lijun; Ran, Qiyun; Wang, Kui

2016-01-01

Multiple cropping provides China with a very important system of intensive cultivation, and can effectively enhance the efficiency of farmland use while improving regional food production and security. A multiple cropping index (MCI), which represents the intensity of multiple cropping and reflects the effects of climate change on agricultural production and cropping systems, often serves as a useful parameter. Therefore, monitoring the dynamic changes in the MCI of farmland over a large area using remote sensing data is essential. For this purpose, nearly 30 years of MCIs related to dry land in the North China Plain (NCP) were efficiently extracted from remotely sensed leaf area index (LAI) data from the Global LAnd Surface Satellite (GLASS). Next, the characteristics of the spatial-temporal change in MCI were analyzed. First, 2162 typical arable sample sites were selected based on a gridded spatial sampling strategy, and then the LAI information was extracted from the samples. Second, the Savizky-Golay filter was used to smooth the LAI time-series data of the samples, and then the MCIs of the samples were obtained using a second-order difference algorithm. Finally, the geo-statistical Kriging method was employed to map the spatial distribution of the MCIs and to obtain a time-series dataset of the MCIs of dry land over the NCP. The results showed that all of the MCIs in the NCP showed an increasing trend over the entire study period and increased most rapidly from 1982 to 2002. Spatially, MCIs decreased from south to north; also, high MCIs were mainly concentrated in the relatively flat areas. In addition, the partial spatial changes of MCIs had clear geographical characteristics, with the largest change in Henan Province. PMID:27104536

Understanding the spectral hardenings and radial distribution of Galactic cosmic rays and Fermi diffuse γ rays with spatially-dependent propagation

NASA Astrophysics Data System (ADS)

Guo, Yi-Qing; Yuan, Qiang

2018-03-01

Recent direct measurements of Galactic cosmic ray spectra by balloon/space-borne detectors reveal spectral hardenings of all major nucleus species at rigidities of a few hundred GV. The all-sky diffuse γ -ray emissions measured by the Fermi Large Area Telescope also show spatial variations of the intensities and spectral indices of cosmic rays. These new observations challenge the traditional simple acceleration and/or propagation scenario of Galactic cosmic rays. In this work, we propose a spatially dependent diffusion scenario to explain all these phenomena. The diffusion coefficient is assumed to be anticorrelated with the source distribution, which is a natural expectation from the charged particle transportation in a turbulent magnetic field. The spatially dependent diffusion model also gives a lower level of anisotropies of cosmic rays, which are consistent with observations by underground muons and air shower experiments. The spectral variations of cosmic rays across the Galaxy can be properly reproduced by this model.

Estimating spatially distributed soil texture using time series of thermal remote sensing - a case study in central Europe

NASA Astrophysics Data System (ADS)

Müller, Benjamin; Bernhardt, Matthias; Jackisch, Conrad; Schulz, Karsten

2016-09-01

For understanding water and solute transport processes, knowledge about the respective hydraulic properties is necessary. Commonly, hydraulic parameters are estimated via pedo-transfer functions using soil texture data to avoid cost-intensive measurements of hydraulic parameters in the laboratory. Therefore, current soil texture information is only available at a coarse spatial resolution of 250 to 1000 m. Here, a method is presented to derive high-resolution (15 m) spatial topsoil texture patterns for the meso-scale Attert catchment (Luxembourg, 288 km2) from 28 images of ASTER (advanced spaceborne thermal emission and reflection radiometer) thermal remote sensing. A principle component analysis of the images reveals the most dominant thermal patterns (principle components, PCs) that are related to 212 fractional soil texture samples. Within a multiple linear regression framework, distributed soil texture information is estimated and related uncertainties are assessed. An overall root mean squared error (RMSE) of 12.7 percentage points (pp) lies well within and even below the range of recent studies on soil texture estimation, while requiring sparser sample setups and a less diverse set of basic spatial input. This approach will improve the generation of spatially distributed topsoil maps, particularly for hydrologic modeling purposes, and will expand the usage of thermal remote sensing products.

Analysis of temporal decay of diffuse broadband sound fields in enclosures by decomposition in powers of an absorption parameter

NASA Astrophysics Data System (ADS)

Bliss, Donald; Franzoni, Linda; Rouse, Jerry; Manning, Ben

2005-09-01

An analysis method for time-dependent broadband diffuse sound fields in enclosures is described. Beginning with a formulation utilizing time-dependent broadband intensity boundary sources, the strength of these wall sources is expanded in a series in powers of an absorption parameter, thereby giving a separate boundary integral problem for each power. The temporal behavior is characterized by a Taylor expansion in the delay time for a source to influence an evaluation point. The lowest-order problem has a uniform interior field proportional to the reciprocal of the absorption parameter, as expected, and exhibits relatively slow exponential decay. The next-order problem gives a mean-square pressure distribution that is independent of the absorption parameter and is primarily responsible for the spatial variation of the reverberant field. This problem, which is driven by input sources and the lowest-order reverberant field, depends on source location and the spatial distribution of absorption. Additional problems proceed at integer powers of the absorption parameter, but are essentially higher-order corrections to the spatial variation. Temporal behavior is expressed in terms of an eigenvalue problem, with boundary source strength distributions expressed as eigenmodes. Solutions exhibit rapid short-time spatial redistribution followed by long-time decay of a predominant spatial mode.

Temporal acceleration of spatially distributed kinetic Monte Carlo simulations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatterjee, Abhijit; Vlachos, Dionisios G.

The computational intensity of kinetic Monte Carlo (KMC) simulation is a major impediment in simulating large length and time scales. In recent work, an approximate method for KMC simulation of spatially uniform systems, termed the binomial {tau}-leap method, was introduced [A. Chatterjee, D.G. Vlachos, M.A. Katsoulakis, Binomial distribution based {tau}-leap accelerated stochastic simulation, J. Chem. Phys. 122 (2005) 024112], where molecular bundles instead of individual processes are executed over coarse-grained time increments. This temporal coarse-graining can lead to significant computational savings but its generalization to spatially lattice KMC simulation has not been realized yet. Here we extend the binomial {tau}-leapmore » method to lattice KMC simulations by combining it with spatially adaptive coarse-graining. Absolute stability and computational speed-up analyses for spatial systems along with simulations provide insights into the conditions where accuracy and substantial acceleration of the new spatio-temporal coarse-graining method are ensured. Model systems demonstrate that the r-time increment criterion of Chatterjee et al. obeys the absolute stability limit for values of r up to near 1.« less

Graffiti for science - erosion painting reveals spatially variable erosivity of sediment-laden flows

NASA Astrophysics Data System (ADS)

Beer, Alexander R.; Kirchner, James W.; Turowski, Jens M.

2016-12-01

Spatially distributed detection of bedrock erosion is a long-standing challenge. Here we show how the spatial distribution of surface erosion can be visualized and analysed by observing the erosion of paint from natural bedrock surfaces. If the paint is evenly applied, it creates a surface with relatively uniform erodibility, such that spatial variability in the erosion of the paint reflects variations in the erosivity of the flow and its entrained sediment. In a proof-of-concept study, this approach provided direct visual verification that sediment impacts were focused on upstream-facing surfaces in a natural bedrock gorge. Further, erosion painting demonstrated strong cross-stream variations in bedrock erosion, even in the relatively narrow (5 m wide) gorge that we studied. The left side of the gorge experienced high sediment throughput with abundant lateral erosion on the painted wall up to 80 cm above the bed, but the right side of the gorge only showed a narrow erosion band 15-40 cm above the bed, likely due to deposited sediment shielding the lower part of the wall. This erosion pattern therefore reveals spatial stream bed aggradation that occurs during flood events in this channel. The erosion painting method provides a simple technique for mapping sediment impact intensities and qualitatively observing spatially distributed erosion in bedrock stream reaches. It can potentially find wide application in both laboratory and field studies.

Spatial distribution and output characteristics of nonpoint source pollution in the Dongjiang River basin in south China

NASA Astrophysics Data System (ADS)

Rong, Q. Q.; Su, M. R.; Yang, Z. F.; Cai, Y. P.; Yue, W. C.; Dang, Z.

2018-02-01

In this research, the Dongjiang River basin was taken as the study area to analyze the spatial distribution and output characteristics of nonpoint source pollution, based on the export coefficient model. The results showed that the annual total nitrogen and phosphorus (i.e. TN and TP) loads from the Dongjiang River basin were 67916114.6 and 7215279.707 kg, respectively. Residents, forestland and pig were the main contributors for the TN load in the Dongjiang River basin, while residents, forestland and rainfed croplands were the three largest contributors for the TP load. The NPS pollution had a significant spatial variation in this area. The pollution loads overall decreased from the northeast to the southwest part of the basin. Also, the pollution loads from the gentle slope area were larger than those from steep slope areas. Among the ten tributary watersheds in the Dongjiang River basin, the TN and TP loads from the Hanxi River watershed were the largest. On the contrary, the Gongzhuang River watershed contributed least to the total pollution loads of the Dongjiang River basin. For the average pollution load intensities, Hanxi River watershed was still the largest. However, the smallest average TN and TP load intensities were in the Xinfeng River watershed.

Combined point and distributed techniques for multidimensional estimation of spatial groundwater-stream water exchange in a heterogeneous sand bed-stream.

NASA Astrophysics Data System (ADS)

Gaona Garcia, J.; Lewandowski, J.; Bellin, A.

2017-12-01

Groundwater-stream water interactions in rivers determine water balances, but also chemical and biological processes in the streambed at different spatial and temporal scales. Due to the difficult identification and quantification of gaining, neutral and losing conditions, it is necessary to combine techniques with complementary capabilities and scale ranges. We applied this concept to a study site at the River Schlaube, East Brandenburg-Germany, a sand bed stream with intense sediment heterogeneity and complex environmental conditions. In our approach, point techniques such as temperature profiles of the streambed together with vertical hydraulic gradients provide data for the estimation of fluxes between groundwater and surface water with the numerical model 1DTempPro. On behalf of distributed techniques, fiber optic distributed temperature sensing identifies the spatial patterns of neutral, down- and up-welling areas by analysis of the changes in the thermal patterns at the streambed interface under certain flow. The study finally links point and surface temperatures to provide a method for upscaling of fluxes. Point techniques provide point flux estimates with essential depth detail to infer streambed structures while the results hardly represent the spatial distribution of fluxes caused by the heterogeneity of streambed properties. Fiber optics proved capable of providing spatial thermal patterns with enough resolution to observe distinct hyporheic thermal footprints at multiple scales. The relation of thermal footprint patterns and temporal behavior with flux results from point techniques enabled the use of methods for spatial flux estimates. The lack of detailed information of the physical driver's spatial distribution restricts the spatial flux estimation to the application of the T-proxy method, whose highly uncertain results mainly provide coarse spatial flux estimates. The study concludes that the upscaling of groundwater-stream water interactions using thermal measurements with combined point and distributed techniques requires the integration of physical drivers because of the heterogeneity of the flux patterns. Combined experimental and modeling approaches may help to obtain more reliable understanding of groundwater-surface water interactions at multiple scales.

Rasdaman for Big Spatial Raster Data

NASA Astrophysics Data System (ADS)

Hu, F.; Huang, Q.; Scheele, C. J.; Yang, C. P.; Yu, M.; Liu, K.

2015-12-01

Spatial raster data have grown exponentially over the past decade. Recent advancements on data acquisition technology, such as remote sensing, have allowed us to collect massive observation data of various spatial resolution and domain coverage. The volume, velocity, and variety of such spatial data, along with the computational intensive nature of spatial queries, pose grand challenge to the storage technologies for effective big data management. While high performance computing platforms (e.g., cloud computing) can be used to solve the computing-intensive issues in big data analysis, data has to be managed in a way that is suitable for distributed parallel processing. Recently, rasdaman (raster data manager) has emerged as a scalable and cost-effective database solution to store and retrieve massive multi-dimensional arrays, such as sensor, image, and statistics data. Within this paper, the pros and cons of using rasdaman to manage and query spatial raster data will be examined and compared with other common approaches, including file-based systems, relational databases (e.g., PostgreSQL/PostGIS), and NoSQL databases (e.g., MongoDB and Hive). Earth Observing System (EOS) data collected from NASA's Atmospheric Scientific Data Center (ASDC) will be used and stored in these selected database systems, and a set of spatial and non-spatial queries will be designed to benchmark their performance on retrieving large-scale, multi-dimensional arrays of EOS data. Lessons learnt from using rasdaman will be discussed as well.

Optimal condition for employing an axicon-generated Bessel beam to fabricate cylindrical microlens arrays

NASA Astrophysics Data System (ADS)

Luo, Zhi; Yin, Kai; Dong, Xinran; Duan, Ji’an

2018-05-01

A numerical algorithm, modelling the transformation from a Gaussian beam to a Bessel beam, is presented for the purpose to study the optimal condition for employing an axicon-generated Bessel beam to fabricate cylindrical microlens arrays (CMLAs). By applying the numerical algorithm to simulate the spatial intensity distribution behind the axicon under different defects of a rotund-apex and different diameter ratios of an incident beam to the axicon, we find that the diffraction effects formed by the axicon edge can be almost eliminated when the diameter ratio is less than 1:2, but the spatial intensity distribution is disturbed dramatically even a few tens of microns deviation of the apex, especially for the front part of the axicon-generated Bessel beam. Fortunately, the lateral intensity profile in the rear part still maintains a desirable Bessel curve. Therefore, the rear part of the Bessel area and the less than 1:2 diameter ratio are the optimal choice for employing an axicon-generated Bessel beam to implement surface microstructures fabrication. Furthermore, by applying the optimal conditions to direct writing microstructures on fused silica with a femtosecond (fs) laser, a large area close-packed CMLA is fabricated. The CMLA presents high quality and uniformity and its optical performance is also demonstrated.

Spatial distribution and risk factors of Schistosoma haematobium and hookworm infections among schoolchildren in Kwale, Kenya

PubMed Central

Chadeka, Evans Asena; Nagi, Sachiyo; Sunahara, Toshihiko; Cheruiyot, Ngetich Benard; Bahati, Felix; Ozeki, Yuriko; Inoue, Manabu; Osada-Oka, Mayuko; Okabe, Mayuko; Hirayama, Yukio; Changoma, Mwatasa; Adachi, Keishi; Mwende, Faith; Kikuchi, Mihoko; Nakamura, Risa; Kalenda, Yombo Dan Justin; Kaneko, Satoshi; Hirayama, Kenji; Shimada, Masaaki; Ichinose, Yoshio; Njenga, Sammy M.; Matsumoto, Sohkichi

2017-01-01

Background Large-scale schistosomiasis control programs are implemented in regions with diverse social and economic environments. A key epidemiological feature of schistosomiasis is its small-scale heterogeneity. Locally profiling disease dynamics including risk factors associated with its transmission is essential for designing appropriate control programs. To determine spatial distribution of schistosomiasis and its drivers, we examined schoolchildren in Kwale, Kenya. Methodology/Principal findings We conducted a cross-sectional study of 368 schoolchildren from six primary schools. Soil-transmitted helminths and Schistosoma mansoni eggs in stool were evaluated by the Kato-Katz method. We measured the intensity of Schistosoma haematobium infection by urine filtration. The geometrical mean intensity of S. haematobium was 3.1 eggs/10 ml urine (school range, 1.4–9.2). The hookworm geometric mean intensity was 3.2 eggs/g feces (school range, 0–17.4). Heterogeneity in the intensity of S. haematobium and hookworm infections was evident in the study area. To identify factors associated with the intensity of helminth infections, we utilized negative binomial generalized linear mixed models. The intensity of S. haematobium infection was associated with religion and socioeconomic status (SES), while that of hookworm infection was related to SES, sex, distance to river and history of anthelmintic treatment. Conclusions/Significance Both S. haematobium and hookworm infections showed micro-geographical heterogeneities in this Kwale community. To confirm and explain our observation of high S. haematobium risk among Muslims, further extensive investigations are necessary. The observed small scale clustering of the S. haematobium and hookworm infections might imply less uniform strategies even at finer scale for efficient utilization of limited resources. PMID:28863133

[Micro-simulation of firms' heterogeneity on pollution intensity and regional characteristics].

PubMed

Zhao, Nan; Liu, Yi; Chen, Ji-Ning

2009-11-01

In the same industrial sector, heterogeneity of pollution intensity exists among firms. There are some errors if using sector's average pollution intensity, which are calculated by limited number of firms in environmental statistic database to represent the sector's regional economic-environmental status. Based on the production function which includes environmental depletion as input, a micro-simulation model on firms' operational decision making is proposed. Then the heterogeneity of firms' pollution intensity can be mechanically described. Taking the mechanical manufacturing sector in Deyang city, 2005 as the case, the model's parameters were estimated. And the actual COD emission intensities of environmental statistic firms can be properly matched by the simulation. The model's results also show that the regional average COD emission intensity calculated by the environmental statistic firms (0.002 6 t per 10 000 yuan fixed asset, 0.001 5 t per 10 000 yuan production value) is lower than the regional average intensity calculated by all the firms in the region (0.003 0 t per 10 000 yuan fixed asset, 0.002 3 t per 10 000 yuan production value). The difference among average intensities in the six counties is significant as well. These regional characteristics of pollution intensity attribute to the sector's inner-structure (firms' scale distribution, technology distribution) and its spatial deviation.

Automatic recognition of seismic intensity based on RS and GIS: a case study in Wenchuan Ms8.0 earthquake of China.

PubMed

Zhang, Qiuwen; Zhang, Yan; Yang, Xiaohong; Su, Bin

2014-01-01

In recent years, earthquakes have frequently occurred all over the world, which caused huge casualties and economic losses. It is very necessary and urgent to obtain the seismic intensity map timely so as to master the distribution of the disaster and provide supports for quick earthquake relief. Compared with traditional methods of drawing seismic intensity map, which require many investigations in the field of earthquake area or are too dependent on the empirical formulas, spatial information technologies such as Remote Sensing (RS) and Geographical Information System (GIS) can provide fast and economical way to automatically recognize the seismic intensity. With the integrated application of RS and GIS, this paper proposes a RS/GIS-based approach for automatic recognition of seismic intensity, in which RS is used to retrieve and extract the information on damages caused by earthquake, and GIS is applied to manage and display the data of seismic intensity. The case study in Wenchuan Ms8.0 earthquake in China shows that the information on seismic intensity can be automatically extracted from remotely sensed images as quickly as possible after earthquake occurrence, and the Digital Intensity Model (DIM) can be used to visually query and display the distribution of seismic intensity.

Cerebral hypoxia during cardiopulmonary bypass: a magnetic resonance imaging study.

PubMed

Mutch, W A; Ryner, L N; Kozlowski, P; Scarth, G; Warrian, R K; Lefevre, G R; Wong, T G; Thiessen, D B; Girling, L G; Doiron, L; McCudden, C; Saunders, J K

1997-09-01

Neurocognitive deficits after open heart operations have been correlated to jugular venous oxygen desaturation on rewarming from hypothermic cardiopulmonary bypass (CPB). Using a porcine model, we looked for evidence of cerebral hypoxia by magnetic resonance imaging during CPB. Brain oxygenation was assessed by T2*-weighted imaging, based on the blood oxygenation level-dependent effect (decreased T2*-weighted signal intensity with increased tissue concentrations of deoxyhemoglobin). Pigs were placed on normothermic CPB, then cooled to 28 degrees C for 2 hours of hypothermic CPB, then rewarmed to baseline temperature. T2*-weighted, imaging was undertaken before CPB, during normothermic CPB, at 30-minute intervals during hypothermic CPB, after rewarming, and then 15 minutes after death. Imaging was with a Bruker 7.0 Tesla, 40-cm bore magnetic resonance scanner with actively shielded gradient coils. Regions of interest from the magnetic resonance images were analyzed to identify parenchymal hypoxia and correlated with jugular venous oxygen saturation. Post-hoc fuzzy clustering analysis was used to examine spatially distributed regions of interest whose pixels followed similar time courses. Attention was paid to pixels showing decreased T2* signal intensity over time. T2* signal intensity decreased with rewarming and in five of seven experiments correlated with the decrease in jugular venous oxygen saturation. T2* imaging with fuzzy clustering analysis revealed two diffusely distributed pixel groups during CPB. One large group of pixels (50% +/- 13% of total pixel count) showed increased T2* signal intensity (well-oxygenated tissue) during hypothermia, with decreased intensity on rewarming. Changes in a second group of pixels (34% +/- 8% of total pixel count) showed a progressive decrease in T2* signal intensity, independent of temperature, suggestive of increased brain hypoxia during CPB. Decreased T2* signal intensity in a diffuse spatial distribution indicates that a large proportion of cerebral parenchyma is hypoxic (evidenced by an increased proportion of tissue deoxyhemoglobin) during CPB in this porcine model. Neuronal damage secondary to parenchymal hypoxia may explain the postoperative neuropsychological dysfunction after cardiac operations.

Spatial heterogeneity of mobilization processes and input pathways of herbicides into a brook in a small agricultural catchment

NASA Astrophysics Data System (ADS)

Doppler, Tobias; Lück, Alfred; Popow, Gabriel; Strahm, Ivo; Winiger, Luca; Gaj, Marcel; Singer, Heinz; Stamm, Christian

2010-05-01

Soil applied herbicides can be transported from their point of application (agricultural field) to surface waters during rain events. There they can have harmful effects on aquatic species. Since the spatial distribution of mobilization and transport processes is very heterogeneous, the contributions of different fields to the total load in a surface water body may differ considerably. The localization of especially critical areas (contributing areas) can help to efficiently minimize herbicide inputs to surface waters. An agricultural field becomes a contributing area when three conditions are met: 1) herbicides are applied, 2) herbicides are mobilized on the field and 3) the mobilized herbicides are transported rapidly to the surface water. In spring 2009, a controlled herbicide application was performed on corn fields in a small (ca 1 km2) catchment with intensive crop production in the Swiss plateau. Subsequently water samples were taken at different locations in the catchment with a high temporal resolution during rain events. We observed both saturation excess and hortonian overland flow during the field campaign. Both can be important mobilization processes depending on the intensity and quantity of the rain. This can lead to different contributing areas during different types of rain events. We will show data on the spatial distribution of herbicide loads during different types of rain events. Also the connectivity of the fields with the brook is spatially heterogeneous. Most of the fields are disconnected from the brook by internal sinks in the catchment, which prevents surface runoff from entering the brook directly. Surface runoff from these disconnected areas can only enter the brook rapidly via macropore-flow into tile drains beneath the internal sinks or via direct shortcuts to the drainage system (maintenance manholes, farmyard or road drains). We will show spatially distributed data on herbicide concentration in purely subsurface systems which shows how important such input pathways can be.

Characterization of traffic-related PM concentration distribution and fluctuation patterns in near-highway urban residential street canyons.

PubMed

Hahn, Intaek; Brixey, Laurie A; Wiener, Russell W; Henkle, Stacy W; Baldauf, Richard

2009-12-01

Analyses of outdoor traffic-related particulate matter (PM) concentration distribution and fluctuation patterns in urban street canyons within a microscale distance of less than 500 m from a highway source are presented as part of the results from the Brooklyn Traffic Real-Time Ambient Pollutant Penetration and Environmental Dispersion (B-TRAPPED) study. Various patterns of spatial and temporal changes in the street canyon PM concentrations were investigated using time-series data of real-time PM concentrations measured during multiple monitoring periods. Concurrent time-series data of local street canyon wind conditions and wind data from the John F. Kennedy (JFK) International Airport National Weather Service (NWS) were used to characterize the effects of various wind conditions on the behavior of street canyon PM concentrations.Our results suggest that wind direction may strongly influence time-averaged mean PM concentration distribution patterns in near-highway urban street canyons. The rooftop-level wind speeds were found to be strongly correlated with the PM concentration fluctuation intensities in the middle sections of the street blocks. The ambient turbulence generated by shifting local wind directions (angles) showed a good correlation with the PM concentration fluctuation intensities along the entire distance of the first and second street blocks only when the wind angle standard deviations were larger than 30 degrees. Within-canyon turbulent shearing, caused by fluctuating local street canyon wind speeds, showed no correlation with PM concentration fluctuation intensities. The time-averaged mean PM concentration distribution along the longitudinal distances of the street blocks when wind direction was mostly constantly parallel to the street was found to be similar to the distribution pattern for the entire monitoring period when wind direction fluctuated wildly. Finally, we showed that two different PM concentration metrics-time-averaged mean concentration and number of concentration peaks above a certain threshold level-can possibly lead to different assessments of spatial concentration distribution patterns.

Spatial luminescence imaging of dopant incorporation in CdTe Films

DOE PAGES

Guthrey, Harvey; Moseley, John; Colegrove, Eric; ...

2017-01-25

State-of-the-art cathodoluminescence (CL) spectrum imaging with spectrum-per-pixel CL emission mapping is applied to spatially profile how dopant elements are incorporated into Cadmium telluride (CdTe). Emission spectra and intensity monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on computational modeling. Our results show that grain boundaries play a role in incorporating dopants in CdTe exposed to copper, phosphorus, and intrinsic point defects in CdTe. Furthermore, the image analysis provides critical, unique feedback to understand dopant incorporation and activation in the inhomogeneous CdTe material, which has struggled to reach high levels of hole density.

The soft X-ray diffuse background

NASA Technical Reports Server (NTRS)

Mccammon, D.; Burrows, D. N.; Sanders, W. T.; Kraushaar, W. L.

1982-01-01

Maps of the diffuse X-ray background intensity covering essentially the entire sky with approx. 7 deg spatial resolution are presented for seven energy bands. The data were obtained on a series of ten sounding rocket flights conducted over a seven-year period. The different nature of the spatial distributions in different bands implies at least three distinct origins for the diffuse X-rays, none of which is well-understood. At energies or approx. 2000 eV, an isotropic and presumably extraglalactic 500 and 1000 eV, an origin which is at least partially galactic seems called for. At energies 284 eV, the observed intensity is anticorrelated with neutral hydrogen column density, but we find it unlikely that this anticorrelation is simply due to absorption of an extragalactic or halo source.

Spatial properties of odd and even low order harmonics generated in gas.

PubMed

Lambert, G; Andreev, A; Gautier, J; Giannessi, L; Malka, V; Petralia, A; Sebban, S; Stremoukhov, S; Tissandier, F; Vodungbo, B; Zeitoun, Ph

2015-01-14

High harmonic generation in gases is developing rapidly as a soft X-ray femtosecond light-source for applications. This requires control over all the harmonics characteristics and in particular, spatial properties have to be kept very good. In previous literature, measurements have always included several harmonics contrary to applications, especially spectroscopic applications, which usually require a single harmonic. To fill this gap, we present here for the first time a detailed study of completely isolated harmonics. The contribution of the surrounding harmonics has been totally suppressed using interferential filtering which is available for low harmonic orders. In addition, this allows to clearly identify behaviors of standard odd orders from even orders obtained by frequency-mixing of a fundamental laser and of its second harmonic. Comparisons of the spatial intensity profiles, of the spatial coherence and of the wavefront aberration level of 5ω at 160 nm and 6ω at 135 nm have then been performed. We have established that the fundamental laser beam aberrations can cause the appearance of a non-homogenous donut-shape in the 6ω spatial intensity distribution. This undesirable effect can be easily controlled. We finally conclude that the spatial quality of an even harmonic can be as excellent as in standard generation.

Coupling biophysical processes and water rights to simulate spatially distributed water use in an intensively managed hydrologic system

NASA Astrophysics Data System (ADS)

Han, Bangshuai; Benner, Shawn G.; Bolte, John P.; Vache, Kellie B.; Flores, Alejandro N.

2017-07-01

Humans have significantly altered the redistribution of water in intensively managed hydrologic systems, shifting the spatiotemporal patterns of surface water. Evaluating water availability requires integration of hydrologic processes and associated human influences. In this study, we summarize the development and evaluation of an extensible hydrologic model that explicitly integrates water rights to spatially distribute irrigation waters in a semi-arid agricultural region in the western US, using the Envision integrated modeling platform. The model captures both human and biophysical systems, particularly the diversion of water from the Boise River, which is the main water source that supports irrigated agriculture in this region. In agricultural areas, water demand is estimated as a function of crop type and local environmental conditions. Surface water to meet crop demand is diverted from the stream reaches, constrained by the amount of water available in the stream, the water-rights-appropriated amount, and the priority dates associated with particular places of use. Results, measured by flow rates at gaged stream and canal locations within the study area, suggest that the impacts of irrigation activities on the magnitude and timing of flows through this intensively managed system are well captured. The multi-year averaged diverted water from the Boise River matches observations well, reflecting the appropriation of water according to the water rights database. Because of the spatially explicit implementation of surface water diversion, the model can help diagnose places and times where water resources are likely insufficient to meet agricultural water demands, and inform future water management decisions.

A new indicator framework for quantifying the intensity of the terrestrial water cycle

NASA Astrophysics Data System (ADS)

Huntington, Thomas G.; Weiskel, Peter K.; Wolock, David M.; McCabe, Gregory J.

2018-04-01

A quantitative framework for characterizing the intensity of the water cycle over land is presented, and illustrated using a spatially distributed water-balance model of the conterminous United States (CONUS). We approach water cycle intensity (WCI) from a landscape perspective; WCI is defined as the sum of precipitation (P) and actual evapotranspiration (AET) over a spatially explicit landscape unit of interest, averaged over a specified time period (step) of interest. The time step may be of any length for which data or simulation results are available (e.g., sub-daily to multi-decadal). We define the storage-adjusted runoff (Q‧) as the sum of actual runoff (Q) and the rate of change in soil moisture storage (ΔS/Δt, positive or negative) during the time step of interest. The Q‧ indicator is demonstrated to be mathematically complementary to WCI, in a manner that allows graphical interpretation of their relationship. For the purposes of this study, the indicators were demonstrated using long-term, spatially distributed model simulations with an annual time step. WCI was found to increase over most of the CONUS between the 1945 to 1974 and 1985 to 2014 periods, driven primarily by increases in P. In portions of the western and southeastern CONUS, Q‧ decreased because of decreases in Q and soil moisture storage. Analysis of WCI and Q‧ at temporal scales ranging from sub-daily to multi-decadal could improve understanding of the wide spectrum of hydrologic responses that have been attributed to water cycle intensification, as well as trends in those responses.

Mapping and determinism of soil microbial community distribution across an agricultural landscape.

PubMed

Constancias, Florentin; Terrat, Sébastien; Saby, Nicolas P A; Horrigue, Walid; Villerd, Jean; Guillemin, Jean-Philippe; Biju-Duval, Luc; Nowak, Virginie; Dequiedt, Samuel; Ranjard, Lionel; Chemidlin Prévost-Bouré, Nicolas

2015-06-01

Despite the relevance of landscape, regarding the spatial patterning of microbial communities and the relative influence of environmental parameters versus human activities, few investigations have been conducted at this scale. Here, we used a systematic grid to characterize the distribution of soil microbial communities at 278 sites across a monitored agricultural landscape of 13 km². Molecular microbial biomass was estimated by soil DNA recovery and bacterial diversity by 16S rRNA gene pyrosequencing. Geostatistics provided the first maps of microbial community at this scale and revealed a heterogeneous but spatially structured distribution of microbial biomass and diversity with patches of several hundreds of meters. Variance partitioning revealed that both microbial abundance and bacterial diversity distribution were highly dependent of soil properties and land use (total variance explained ranged between 55% and 78%). Microbial biomass and bacterial richness distributions were mainly explained by soil pH and texture whereas bacterial evenness distribution was mainly related to land management. Bacterial diversity (richness, evenness, and Shannon index) was positively influenced by cropping intensity and especially by soil tillage, resulting in spots of low microbial diversity in soils under forest management. Spatial descriptors also explained a small but significant portion of the microbial distribution suggesting that landscape configuration also shapes microbial biomass and bacterial diversity. © 2015 The Authors. MicrobiologyOpen published by John Wiley & Sons Ltd.

Compensation for the phase-type spatial periodic modulation of the near-field beam at 1053 nm

NASA Astrophysics Data System (ADS)

Gao, Yaru; Liu, Dean; Yang, Aihua; Tang, Ruyu; Zhu, Jianqiang

2017-10-01

A phase-only spatial light modulator is used to provide and compensate for the spatial periodic modulation (SPM) of the near-field beam at the near infrared at 1053nm wavelength with an improved iterative weight-based method. The transmission characteristics of the incident beam has been changed by a spatial light modulator (SLM) to shape the spatial intensity of the output beam. The propagation and reverse propagation of the light in free space are two important processes in the iterative process. The based theory is the beam angular spectrum transmit formula (ASTF) and the principle of the iterative weight-based method. We have made two improvements to the originally proposed iterative weight-based method. We select the appropriate parameter by choosing the minimum value of the output beam contrast degree and use the MATLAB built-in angle function to acquire the corresponding phase of the light wave function. The required phase that compensates for the intensity distribution of the incident SPM beam is iterated by this algorithm, which can decrease the magnitude of the SPM of the intensity on the observation plane. The experimental results show that the phase-type SPM of the near-field beam is subject to a certain restriction. We have also analyzed some factors that make the results imperfect. The experiment results verifies the possible applicability of this iterative weight-based method to compensate for the SPM of the near-field beam.

Selecting a sampling method to aid in vegetation management decisions in loblolly pine plantations

Treesearch

David R. Weise; Glenn R. Glover

1993-01-01

Objective methods to evaluate hardwood competition in young loblolly pine (Pinustaeda L.) plantations are not widely used in the southeastern United States. Ability of common sampling rules to accurately estimate hardwood rootstock attributes at low sampling intensities and across varying rootstock spatial distributions is unknown. Fixed area plot...

Test Section Turbulence in the AEDC/VKF Supersonic/Hypersonic Wind Tunnels

DTIC Science & Technology

1981-07-01

8 4.3 Ins t rumen ta t ion ....................................................... 18...Pressure Fluctuation Spectral Content in AEDC Tunnels A and B (Based on FY79 Pitot Probe), Af = 200 Hz...intensity, spatial distribution, and spectral content , has become increasingly important in the analysis of test data. The sector- supported model in the

National FIA plot intensification procedure report

Treesearch

Jock A. Blackard; Paul L. Patterson

2014-01-01

The Forest Inventory and Analysis (FIA) program of the U.S. Forest Service (USFS) measures a spatially distributed base grid of forest inventory plots across the United States. The sampling intensity of plots may be increased in some regions when warranted by specific inventory objectives. Several intensification methods have been developed within FIA and USFS National...

Detection of rheumatoid arthritis in humans by fluorescence imaging

NASA Astrophysics Data System (ADS)

Ebert, Bernd; Dziekan, Thomas; Weissbach, Carmen; Mahler, Marianne; Schirner, Michael; Berliner, Birgitt; Bauer, Daniel; Voigt, Jan; Berliner, Michael; Bahner, Malte L.; Macdonald, Rainer

2010-02-01

The blood pool agent indo-cyanine green (ICG) has been investigated in a prospective clinical study for detection of rheumatoid arthritis using fluorescence imaging. Temporal behavior as well as spatial distribution of fluorescence intensity are suited to differentiate healthy and inflamed finger joints after i.v. injection of an ICG bolus.

Spatial and spectral interpolation of ground-motion intensity measure observations

USGS Publications Warehouse

Worden, Charles; Thompson, Eric M.; Baker, Jack W.; Bradley, Brendon A.; Luco, Nicolas; Wilson, David

2018-01-01

Following a significant earthquake, ground‐motion observations are available for a limited set of locations and intensity measures (IMs). Typically, however, it is desirable to know the ground motions for additional IMs and at locations where observations are unavailable. Various interpolation methods are available, but because IMs or their logarithms are normally distributed, spatially correlated, and correlated with each other at a given location, it is possible to apply the conditional multivariate normal (MVN) distribution to the problem of estimating unobserved IMs. In this article, we review the MVN and its application to general estimation problems, and then apply the MVN to the specific problem of ground‐motion IM interpolation. In particular, we present (1) a formulation of the MVN for the simultaneous interpolation of IMs across space and IM type (most commonly, spectral response at different oscillator periods) and (2) the inclusion of uncertain observation data in the MVN formulation. These techniques, in combination with modern empirical ground‐motion models and correlation functions, provide a flexible framework for estimating a variety of IMs at arbitrary locations.

Uncertainty of High Intensity Therapeutic Ultrasound (HITU) Field Characterization with Hydrophones: Effects of Nonlinearity, Spatial Averaging, and Complex Sensitivity

PubMed Central

Liu, Yunbo; Wear, Keith A.; Harris, Gerald R.

2017-01-01

Reliable acoustic characterization is fundamental for patient safety and clinical efficacy during high intensity therapeutic ultrasound (HITU) treatment. Technical challenges, such as measurement uncertainty and signal analysis still exist for HITU exposimetry using ultrasound hydrophones. In this work, four hydrophones were compared for pressure measurement: a robust needle hydrophone, a small PVDF capsule hydrophone and two different fiber-optic hydrophones. The focal waveform and beam distribution of a single element HITU transducer (1.05 MHz and 3.3 MHz) were evaluated. Complex deconvolution between the hydrophone voltage signal and frequency-dependent complex sensitivity was performed to obtain pressure waveform. Compressional pressure, rarefactional pressure, and focal beam distribution were compared up to 10.6/−6.0 MPa (p+ and p−) (1.05 MHz) and 20.65/−7.20 MPa (3.3 MHz). In particular, the effects of spatial averaging, local nonlinear distortion, complex deconvolution and hydrophone damage thresholds were investigated. This study showed an uncertainty of no better than 10–15% on hydrophone-based HITU pressure characterization. PMID:28735734

Variation of High-Intensity Therapeutic Ultrasound (HITU) Pressure Field Characterization: Effects of Hydrophone Choice, Nonlinearity, Spatial Averaging and Complex Deconvolution.

PubMed

Liu, Yunbo; Wear, Keith A; Harris, Gerald R

2017-10-01

Reliable acoustic characterization is fundamental for patient safety and clinical efficacy during high-intensity therapeutic ultrasound (HITU) treatment. Technical challenges, such as measurement variation and signal analysis, still exist for HITU exposimetry using ultrasound hydrophones. In this work, four hydrophones were compared for pressure measurement: a robust needle hydrophone, a small polyvinylidene fluoride capsule hydrophone and two fiberoptic hydrophones. The focal waveform and beam distribution of a single-element HITU transducer (1.05 MHz and 3.3 MHz) were evaluated. Complex deconvolution between the hydrophone voltage signal and frequency-dependent complex sensitivity was performed to obtain pressure waveforms. Compressional pressure (p + ), rarefactional pressure (p - ) and focal beam distribution were compared up to 10.6/-6.0 MPa (p + /p - ) (1.05 MHz) and 20.65/-7.20 MPa (3.3 MHz). The effects of spatial averaging, local non-linear distortion, complex deconvolution and hydrophone damage thresholds were investigated. This study showed a variation of no better than 10%-15% among hydrophones during HITU pressure characterization. Published by Elsevier Inc.

THE TIME EVOLUTION OF HH 1 FROM FOUR EPOCHS OF HST IMAGES

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raga, A. C.; Esquivel, A.; Reipurth, B.

We present an analysis of four epochs of Hα and [S ii] λλ 6716/6731 Hubble Space Telescope (HST) images of HH 1. For determining proper motions, we explore a new method based on the analysis of spatially degraded images obtained convolving the images with wavelet functions of chosen widths. With this procedure, we are able to generate maps of proper motion velocities along and across the outflow axis, as well as (angularly integrated) proper motion velocity distributions. From the four available epochs, we find the time evolution of the velocities, intensities, and spatial distribution of the line emission. We find that overmore » the last two decades HH 1 shows a clear acceleration. Also, the Hα and [S ii] intensities first dropped and then recovered in the more recent (2014) images. Finally, we show a comparison between the two available HST epochs of [O iii] λ 5007 (1994 and 2014), in which we see a clear drop in the value of the [O iii]/Hα ratio.« less

A succinct method to generate multi-type HCV beams with a spatial spiral varying retardation-plate

NASA Astrophysics Data System (ADS)

Qi, Junli; Zhang, Hui; Pan, Baoguo; Deng, Haifei; Yang, Jinhong; Shi, Bo; Wang, Hui; Du, Ang; Wang, Weihua; Li, Xiujian

2018-03-01

A simple novel and practical scheme is presented to generate high-power cylindrical vector (HCV) beams with a 36-segment spiral varying retardation-plate sandwiched between two quarter-wave plates (QWPs). Four kinds of HCV beams, such as radially polarized beam and azimuthally polarized beam, are formed by simply rotating two QWPs. A segmented spiral varying phase-plate with isotropy is used to modulate spatial phase distribution to generate in-phase HCV beams. The intensity distributions and polarizing properties of HCV beams are investigated and analyzed in detail. It is demonstrated experimentally that the system can effectively generate multi-type HCV beams with high purity up to 99%, and it can be manufactured as cylindrical vector beam converter commercially.

Spatial effect of conical angle on optical-thermal distribution for circumferential photocoagulation

PubMed Central

Truong, Van Gia; Park, Suhyun; Tran, Van Nam; Kang, Hyun Wook

2017-01-01

A uniformly diffusing applicator can be advantageous for laser treatment of tubular tissue. The current study investigated various conical angles for diffuser tips as a critical factor for achieving radially uniform light emission. A customized goniometer was employed to characterize the spatial uniformity of the light propagation. An ex vivo model was developed to quantitatively compare the temperature development and irreversible tissue coagulation. The 10-mm diffuser tip with angle at 25° achieved a uniform longitudinal intensity profile (i.e., 0.90 ± 0.07) as well as a consistent thermal denaturation on the tissue. The proposed conical angle can be instrumental in determining the uniformity of light distribution for the photothermal treatment of tubular tissue. PMID:29296495

Exploring the Influence of Impervious Surface Density and Shape on Urban Heat Islands in the Northeast USA Using MODIS and Landsat

NASA Technical Reports Server (NTRS)

Zhang, Ping; Imhoff, Marc L.; Bounoua, Lahouri; Wolfe, Robert E.

2011-01-01

Impervious surface area (ISA) from the National Land Cover Database (NLCD) 2001 and land surface temperature (LST) from MODIS averaged over three annual cycles (2003-2005) are used in a spatial analysis to assess the urban heat island (UHI) signature and its relationship to settlement size and shape, development intensity distribution, and land cover composition for 42 urban settlements embedded in forest biomes in the Northeastern United States. Development intensity zones, based on percent ISA, are defined for each urban area emanating outward from the urban core to nearby rural areas and are used to stratify land surface temperature. The stratification is further constrained by biome type and elevation to insure objective intercomparisons between urban zones within an urban settlement and between settlements. Stratification based on ISA allows the definition of hierarchically ordered urban zones that are consistent across urban settlements and scales. In addition to the surrounding ecological context, we find that the settlement size and shape as well as the development intensity distribution significantly influence the amplitude of summer daytime UHI. Within the Northeastern US temperate broadleaf mixed forest, UHI magnitude is positively related to the logarithm of the urban area size. Our study indicates that for similar urban area sizes, the development intensity distribution is one of the major drivers of UHI. In addition to urban area size and development intensity distribution, this analysis shows that both the shape of the urban area and the land cover composition in the surrounding rural area play an important role in modulating the UHI magnitude in different urban settlements. Our results indicate that remotely sensed urban area size and shape as well as the development intensity distribution influence UHI amplitude across regional scales.

Network of Spaces and Interaction-Related Behaviors in Adult Intensive Care Units

PubMed Central

Rashid, Mahbub; Boyle, Diane K.; Crosser, Michael

2014-01-01

Using three spatial network measures of “space syntax”, this correlational study describes four interaction-related behaviors among three groups of users in relation to visibility and accessibility of spaces in four adult intensive care units (ICUs) of different size, geometry, and specialty. Systematic field observations of interaction-related behaviors show significant differences in spatial distribution of interaction-related behaviors in the ICUs. Despite differences in unit characteristics and interaction-related behaviors, the study finds that when nurses and physicians “interact while sitting” they prefer spaces that help maintain a high level of environmental awareness; that when nurses “walk” and “interact while walking” they avoid spaces with better global access and visibility; and that everyone in ICUs “walk” more in spaces with higher control over neighboring spaces. It is argued that such consistent behavioral patterns occur due to the structural similarities of spatial networks over and above the more general functional similarities of ICUs. PMID:25469838

Extracting spatial information from networks with low-order eigenvectors

NASA Astrophysics Data System (ADS)

Cucuringu, Mihai; Blondel, Vincent D.; Van Dooren, Paul

2013-03-01

We consider the problem of inferring meaningful spatial information in networks from incomplete information on the connection intensity between the nodes of the network. We consider two spatially distributed networks: a population migration flow network within the US, and a network of mobile phone calls between cities in Belgium. For both networks we use the eigenvectors of the Laplacian matrix constructed from the link intensities to obtain informative visualizations and capture natural geographical subdivisions. We observe that some low-order eigenvectors localize very well and seem to reveal small geographically cohesive regions that match remarkably well with political and administrative boundaries. We discuss possible explanations for this observation by describing diffusion maps and localized eigenfunctions. In addition, we discuss a possible connection with the weighted graph cut problem, and provide numerical evidence supporting the idea that lower-order eigenvectors point out local cuts in the network. However, we do not provide a formal and rigorous justification for our observations.

The Evolution of Galaxies Through the Spatial Distribution of Their Globular Clusters: the Brightest Galaxies in Fornax

NASA Astrophysics Data System (ADS)

Zegeye, David W.

2018-01-01

We present a study of the evolution of the 10 brightest galaxies in the Fornax Cluster, as reconstructed through their Globular Cluster (GC) populations. GCs can be characterized by their projected two-dimensional (2D) spatial distribution. Over- or under-densities in the GC distribution, can be linked to events in the host galaxy assembly history, and used to constrain the properties of their progenitors. With HST/ACS imaging, we identified significant structures in the GC distribution of the 10 galaxies investigated, with some of the galaxies possessing structures with >10-sigma significance. GC over-densities have been found within the galaxies, with significant differences between the red and blue GC population. For elongated galaxies, structures are preferentially to be aligned along the major axis. Fornax Cluster galaxies appear to be more dynamically relaxed than the Virgo Cluster galaxies previously investigated with the same methodology by D'Abrusco et al. (2016). However, from these observations, the evident imprints left in the spatial distribution of GCs in these galaxies suggest a similarly intense history of interactions.The SAO REU program is funded by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant AST-1659473, and by the Smithsonian Institution.

Spatial distribution of cloud droplets in a turbulent cloud-chamber flow

NASA Astrophysics Data System (ADS)

Jaczewski, A.; Malinowski, S. P.

2005-07-01

We present the results of a laboratory study of the spatial distribution of cloud droplets in a turbulent environment. An artificial, weakly turbulent cloud, consisting of droplets of diameter around 14 m, is observed in a laboratory chamber. Droplets on a vertical cross-section through the cloud interior are imaged using laser sheet photography. Images are digitized and numerically processed in order to retrieve droplet positions in a vertical plane. The spatial distribution of droplets in the range of scales, l, from 4 to 80 mm is characterized by: the clustering index CI(l), the volume averaged pair correlation function eta;(l) and a local density defined on a basis of correlation analysis. The results indicate that, even in weak turbulence in the chamber that is less intense and less intermittent than turbulence observed in clouds, droplets are not spread according to the Poisson distribution. The importance of this deviation from the Poisson distribution is unclear when looking at CI(l) and (l). The local density indicates that in small scales each droplet has, on average, more neighbours than expected from the average droplet concentration and gives a qualitative and intuitive measure of clustering.

Bisphenol analogues in surface water and sediment from the shallow Chinese freshwater lakes: Occurrence, distribution, source apportionment, and ecological and human health risk.

PubMed

Yan, Zhengyu; Liu, Yanhua; Yan, Kun; Wu, Shengmin; Han, Zhihua; Guo, Ruixin; Chen, Meihong; Yang, Qiulian; Zhang, Shenghu; Chen, Jianqiu

2017-10-01

Compared to Bisphenol A (BPA), current knowledge on the spatial distribution, potential sources and environmental risk assessment of other bisphenol analogues (BPs) remains limited. The occurrence, distribution and sources of seven BPs were investigated in the surface water and sediment from Taihu Lake and Luoma Lake, which are the Chinese shallow freshwater lakes. Because there are many industries and living areas around Taihu Lake, the total concentrations of ∑BPs were much higher than that in Luoma Lake, which is away from the industry-intensive areas. For the two lakes, BPA was still the dominant BPs in both surface water and sediment, followed by BPF and BPS. The spatial distribution and principal component analysis showed that BPs in Luoma Lake was relatively homogeneous and the potential sources were relatively simple than that in Taihu Lake. The spatial distribution of BPs in sediment of Taihu Lake indicated that ∑BPs positively correlated with the TOC content. For both Taihu Lake and Luoma Lake, the risk assessment at the sampling sites showed that no high risk in surface water and sediment (RQ t  < 1.0, and EEQ t  < 1.0 ng E 2 /L). Copyright © 2017 Elsevier Ltd. All rights reserved.

Experimental Profiling of a Non-truncated Focused Gaussian Beam and Fine-tuning of the Quadratic Phase in the Fresnel Gaussian Shape Invariant

DOE Office of Scientific and Technical Information (OSTI.GOV)

S., Juan Manuel Franco; Cywiak, Moises; Cywiak, David

2015-06-24

A homodyne profiler is used for recording the intensity distribution of focused non-truncated Gaussian beams. The spatial distributions are obtained at planes in the vicinity of the back-focal plane of a focusing lens placed at different distances from a He–Ne laser beam with a Gaussian intensity profile. Comparisons of the experimental data with those obtained from the analytical equations for an ideal focusing lens allow us to propose formulae to fine-tune the quadratic term in the Fresnel Gaussian shape invariant at each interface of the propagated field. Furthermore, we give analytical expressions to calculate adequately the propagation of the fieldmore » through an optical system.« less

GREAT: a gradient-based color-sampling scheme for Retinex.

PubMed

Lecca, Michela; Rizzi, Alessandro; Serapioni, Raul Paolo

2017-04-01

Modeling the local color spatial distribution is a crucial step for the algorithms of the Milano Retinex family. Here we present GREAT, a novel, noise-free Milano Retinex implementation based on an image-aware spatial color sampling. For each channel of a color input image, GREAT computes a 2D set of edges whose magnitude exceeds a pre-defined threshold. Then GREAT re-scales the channel intensity of each image pixel, called target, by the average of the intensities of the selected edges weighted by a function of their positions, gradient magnitudes, and intensities relative to the target. In this way, GREAT enhances the input image, adjusting its brightness, contrast and dynamic range. The use of the edges as pixels relevant to color filtering is justified by the importance that edges play in human color sensation. The name GREAT comes from the expression "Gradient RElevAnce for ReTinex," which refers to the threshold-based definition of a gradient relevance map for edge selection and thus for image color filtering.

Study on the generation of a vortex laser beam by using phase-only liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Ma, Haotong; Hu, Haojun; Xie, Wenke; Xu, Xiaojun

2013-09-01

The generation of vortex laser beam by using phase-only liquid crystal spatial light modulator (LC-SLM) combined with the spiral phase screen is experimentally and theoretically studied. Results show that Gaussian and dark hollow vortex laser beams can be generated by using this method successfully. Differing with the Gaussian and dark hollow beams, far field intensities of the generated vortex laser beams still exhibit dark hollow distributions. The comparisons between the ideal generation and experimental generation of vortex laser beams with different optical topological charges by using phase only LC-SLM is investigated in detail. Compared with the ideal generated vortex laser beam, phase distribution of the experimental generated vortex laser beam contains many phase singularities, the number of which is the same as that of the optical topological charges. The corresponding near field and far field dark hollow intensity distributions of the generated vortex laser beams exhibit discontinuous in rotational direction. Detailed theoretical analysis show that the main reason for the physical phenomenon mentioned above is the response error of phase only LC-SLM. These studies can provide effective guide for the generation of vortex laser beam by using phase only LC-SLM for optical tweezers and free space optical communication.

Microscopic Distributions of Defect Luminescence From Subgrain Boundaries in Multicrystalline Silicon Wafers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nguyen, Hieu T.; Jensen, Mallory A.; Li, Li

We investigate the microscopic distributions of sub-band-gap luminescence emission (the so-called D-lines D1/D2/D3/D4) and the band-to-band luminescence intensity, near recombination-active sub-grain boundaries in multicrystalline silicon wafers for solar cells. We find that the sub-band-gap luminescence from decorating defects/impurities (D1/D2) and from intrinsic dislocations (D3/D4) have distinctly different spatial distributions, and are asymmetric across the sub-grain boundaries. The presence of D1/D2 is correlated with a strong reduction in the band-to-band luminescence, indicating a higher recombination activity. In contrast, D3/D4 emissions are not strongly correlated with the band-to-band intensity. Based on spatially-resolved, synchrotron-based micro-X-ray fluorescence measurements of metal impurities, we confirm thatmore » high densities of metal impurities are present at locations with strong D1/D2 emission but low D3/D4 emission. Finally, we show that the observed asymmetry of the sub-band-gap luminescence across the sub-grain boundaries is due to their inclination below the wafer surface. Based on the luminescence asymmetries, the sub-grain boundaries are shown to share a common inclination locally, rather than be orientated randomly.« less

Temporal and spatial distribution of gentamicin in the peripheral vestibular system after transtympanic administration in guinea pigs

PubMed Central

Zhang, Ru; Zhang, Yi-Bo; Dai, Chun-Fu; Steyger, Peter S.

2013-01-01

Background and objective Transtympanic administration of gentamicin is effective for treating patients with intractable vertigo. This study explored the spatial and temporal distribution of gentamicin in vestibular end-organs after transtympanic administration. Methods Thirty guinea pigs were transtympanically injected with gentamicin conjugated to Texas Red (GTTR) and their vestibular end-organs examined after various survival periods. Another 9 guinea pigs received GTTR at different doses. Nine animals received Texas Red only and served as controls. We used confocal microscopy to determine the cellular distribution of GTTR in semicircular canal cristae, as well as the utricular and saccular maculae. Results The most intense GTTR labeling was present in the saccule compared to other vestibular end-organs. GTTR fluorescence was detected predominantly in type I hair cells, type II hair cells and transitional cells after a single transtympanic dose of GTTR (0.1 mg/ml, 0.05 ml), while only weak fluorescence was observed in non-sensory cells such as supporting cells, dark cells and lumenal epithelial cells. Transitional cells displayed intense GTTR fluorescence in the supra-nuclear regions 24 h after transtympanic injection that was retained for at least 4 weeks. A decreasing spatial gradient of GTTR fluorescence was observed sensory epithelial regions containing central type I to peripheral type I and then type II hair cells in the crista ampullaris, and from striolar to extra-striolar hair cells within the vestibular macula. GTTR fluorescence extended from being restricted to the apical cytoplasm at lower doses to the entire cell body of type I hair cells with increasing dose. GTTR fluorescence reached peak intensities for individual regions of interest within the cristae and maculae between 3 and 7 days after transtympanic injection. Conclusion The saccular uptake of GTTR is greater than other vestibular end-organs after transtympanic injection in the semicircular canals. PMID:23380663

Combining spray nozzle simulators with meshes: characterization of rainfall intensity and drop properties

NASA Astrophysics Data System (ADS)

Carvalho, Sílvia C. P.; de Lima, João L. M. P.; de Lima, M. Isabel P.

2013-04-01

Rainfall simulators can be a powerful tool to increase our understanding of hydrological and geomorphological processes. Nevertheless, rainfall simulators' design and operation might be rather demanding, for achieving specific rainfall intensity distributions and drop characteristics. The pressurized simulators have some advantages over the non-pressurized simulators: drops do not rely on gravity to reach terminal velocity, but are sprayed out under pressure; pressurized simulators also yield a broad range of drop sizes in comparison with drop-formers simulators. The main purpose of this study was to explore in the laboratory the potential of combining spray nozzle simulators with meshes in order to change rainfall characteristics (rainfall intensity and diameters and fall speed of drops). Different types of spray nozzles were tested, such as single full-cone and multiple full-cone nozzles. The impact of the meshes on the simulated rain was studied by testing different materials (i.e. plastic and steel meshes), square apertures and wire thicknesses, and different vertical distances between the nozzle and the meshes underneath. The diameter and fall speed of the rain drops were measured using a Laser Precipitation Monitor (Thies Clima). The rainfall intensity range and coefficients of uniformity of the sprays and the drop size distribution, fall speed and kinetic energy were analysed. Results show that when meshes intercept drop trajectories the spatial distribution of rainfall intensity and the drop size distribution are affected. As the spray nozzles generate typically small drop sizes and narrow drop size distributions, meshes can be used to promote the formation of bigger drops and random their landing positions.

Estimating recharge rates with analytic element models and parameter estimation

USGS Publications Warehouse

Dripps, W.R.; Hunt, R.J.; Anderson, M.P.

2006-01-01

Quantifying the spatial and temporal distribution of recharge is usually a prerequisite for effective ground water flow modeling. In this study, an analytic element (AE) code (GFLOW) was used with a nonlinear parameter estimation code (UCODE) to quantify the spatial and temporal distribution of recharge using measured base flows as calibration targets. The ease and flexibility of AE model construction and evaluation make this approach well suited for recharge estimation. An AE flow model of an undeveloped watershed in northern Wisconsin was optimized to match median annual base flows at four stream gages for 1996 to 2000 to demonstrate the approach. Initial optimizations that assumed a constant distributed recharge rate provided good matches (within 5%) to most of the annual base flow estimates, but discrepancies of >12% at certain gages suggested that a single value of recharge for the entire watershed is inappropriate. Subsequent optimizations that allowed for spatially distributed recharge zones based on the distribution of vegetation types improved the fit and confirmed that vegetation can influence spatial recharge variability in this watershed. Temporally, the annual recharge values varied >2.5-fold between 1996 and 2000 during which there was an observed 1.7-fold difference in annual precipitation, underscoring the influence of nonclimatic factors on interannual recharge variability for regional flow modeling. The final recharge values compared favorably with more labor-intensive field measurements of recharge and results from studies, supporting the utility of using linked AE-parameter estimation codes for recharge estimation. Copyright ?? 2005 The Author(s).

Development of an Asset Value Map for Disaster Risk Assessment in China by Spatial Disaggregation Using Ancillary Remote Sensing Data.

PubMed

Wu, Jidong; Li, Ying; Li, Ning; Shi, Peijun

2018-01-01

The extent of economic losses due to a natural hazard and disaster depends largely on the spatial distribution of asset values in relation to the hazard intensity distribution within the affected area. Given that statistical data on asset value are collected by administrative units in China, generating spatially explicit asset exposure maps remains a key challenge for rapid postdisaster economic loss assessment. The goal of this study is to introduce a top-down (or downscaling) approach to disaggregate administrative-unit level asset value to grid-cell level. To do so, finding the highly correlated "surrogate" indicators is the key. A combination of three data sets-nighttime light grid, LandScan population grid, and road density grid, is used as ancillary asset density distribution information for spatializing the asset value. As a result, a high spatial resolution asset value map of China for 2015 is generated. The spatial data set contains aggregated economic value at risk at 30 arc-second spatial resolution. Accuracy of the spatial disaggregation reflects redistribution errors introduced by the disaggregation process as well as errors from the original ancillary data sets. The overall accuracy of the results proves to be promising. The example of using the developed disaggregated asset value map in exposure assessment of watersheds demonstrates that the data set offers immense analytical flexibility for overlay analysis according to the hazard extent. This product will help current efforts to analyze spatial characteristics of exposure and to uncover the contributions of both physical and social drivers of natural hazard and disaster across space and time. © 2017 Society for Risk Analysis.

Inhomogeneity Based Characterization of Distribution Patterns on the Plasma Membrane

PubMed Central

Paparelli, Laura; Corthout, Nikky; Wakefield, Devin L.; Sannerud, Ragna; Jovanovic-Talisman, Tijana; Annaert, Wim; Munck, Sebastian

2016-01-01

Cell surface protein and lipid molecules are organized in various patterns: randomly, along gradients, or clustered when segregated into discrete micro- and nano-domains. Their distribution is tightly coupled to events such as polarization, endocytosis, and intracellular signaling, but challenging to quantify using traditional techniques. Here we present a novel approach to quantify the distribution of plasma membrane proteins and lipids. This approach describes spatial patterns in degrees of inhomogeneity and incorporates an intensity-based correction to analyze images with a wide range of resolutions; we have termed it Quantitative Analysis of the Spatial distributions in Images using Mosaic segmentation and Dual parameter Optimization in Histograms (QuASIMoDOH). We tested its applicability using simulated microscopy images and images acquired by widefield microscopy, total internal reflection microscopy, structured illumination microscopy, and photoactivated localization microscopy. We validated QuASIMoDOH, successfully quantifying the distribution of protein and lipid molecules detected with several labeling techniques, in different cell model systems. We also used this method to characterize the reorganization of cell surface lipids in response to disrupted endosomal trafficking and to detect dynamic changes in the global and local organization of epidermal growth factor receptors across the cell surface. Our findings demonstrate that QuASIMoDOH can be used to assess protein and lipid patterns, quantifying distribution changes and spatial reorganization at the cell surface. An ImageJ/Fiji plugin of this analysis tool is provided. PMID:27603951

Spatially distributed effects of mental exhaustion on resting-state FMRI networks.

PubMed

Esposito, Fabrizio; Otto, Tobias; Zijlstra, Fred R H; Goebel, Rainer

2014-01-01

Brain activity during rest is spatially coherent over functional connectivity networks called resting-state networks. In resting-state functional magnetic resonance imaging, independent component analysis yields spatially distributed network representations reflecting distinct mental processes, such as intrinsic (default) or extrinsic (executive) attention, and sensory inhibition or excitation. These aspects can be related to different treatments or subjective experiences. Among these, exhaustion is a common psychological state induced by prolonged mental performance. Using repeated functional magnetic resonance imaging sessions and spatial independent component analysis, we explored the effect of several hours of sustained cognitive performances on the resting human brain. Resting-state functional magnetic resonance imaging was performed on the same healthy volunteers in two days, with and without, and before, during and after, an intensive psychological treatment (skill training and sustained practice with a flight simulator). After each scan, subjects rated their level of exhaustion and performed an N-back task to evaluate eventual decrease in cognitive performance. Spatial maps of selected resting-state network components were statistically evaluated across time points to detect possible changes induced by the sustained mental performance. The intensive treatment had a significant effect on exhaustion and effort ratings, but no effects on N-back performances. Significant changes in the most exhausted state were observed in the early visual processing and the anterior default mode networks (enhancement) and in the fronto-parietal executive networks (suppression), suggesting that mental exhaustion is associated with a more idling brain state and that internal attention processes are facilitated to the detriment of more extrinsic processes. The described application may inspire future indicators of the level of fatigue in the neural attention system.

Specific features of waveguide recombination in laser structures with asymmetric barrier layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Polubavkina, Yu. S., E-mail: polubavkina@mail.ru; Zubov, F. I.; Moiseev, E. I.

2017-02-15

The spatial distribution of the intensity of the emission caused by recombination appearing at a high injection level (up to 30 kA/cm{sup 2}) in the waveguide layer of a GaAs/AlGaAs laser structure with GaInP and AlGaInAs asymmetric barrier layers is studied by means of near-field scanning optical microscopy. It is found that the waveguide luminescence in such a laser, which is on the whole less intense as compared to that observed in a similar laser without asymmetric barriers, is non-uniformly distributed in the waveguide, so that the distribution maximum is shifted closer to the p-type cladding layer. This can bemore » attributed to the ability of the GaInP barrier adjoining the quantum well on the side of the n-type cladding layer to suppress the hole transport.« less

Development of an algorithm for corneal reshaping with a scanning laser beam

NASA Astrophysics Data System (ADS)

Shen, Jin-Hui; Söderberg, Per; Matsui, Takaaki; Manns, Fabrice; Parel, Jean-Marie

1995-07-01

The corneal-ablation rate, the beam-intensity distribution, and the initial and the desired corneal topographies are used to calculate a spatial distribution map of laser pulses. The optimal values of the parameters are determined with a computer model, for a system that produces 213-nm radiation with a Gaussian beam-intensity distribution and a peak radiant exposure of 400 mJ/cm2. The model shows that with a beam diameter of 0.5 mm, an overlap of 80%, and a 5-mm treatment zone, the roughness is less than 6% of the central ablation depth, the refractive error after correction is less than 0.1 D for corrections of myopia of 1, 3, and 6 D and less than 0.4 D for a correction of myopia of 10 D, and the number of pulses per diopter of

Visualization of drug distribution of topical minocycline in human facial skin with fluorescence microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Hermsmeier, Maiko; Sawant, Tanvee; Lac, Diana; Yamamoto, Akira; Chen, Xin; Nagavarapu, Usha; Evans, Conor L.; Chan, Kin Foong

2017-02-01

Minocycline is an antibiotic regularly prescribed to treat acne vulgaris. The only commercially available minocycline comes in an oral dosage form, which often results in systemic adverse effects. A topical minocycline composition (BPX-01) was developed to provide localized and targeted delivery to the epidermis and pilosebaceous unit where acne-related bacteria, Propionibacterium acnes (P. acnes), reside. As minocycline is a known fluorophore, fluorescence microscopy was performed to investigate its potential use in visualizing minocycline distribution within tissues. BPX-01 with various concentrations of minocycline, was applied topically to freshly excised human facial skin specimens. Spatial distribution of minocycline and its fluorescence intensity within the stratum corneum, epidermis, dermis, and pilosebaceous unit were assessed. The resulting fluorescence intensity data as a function of minocycline concentration may indicate clinically relevant therapeutic doses of topical BPX-01 needed to kill P. acnes and reduce inflammation for successful clinical outcomes.

Investigating distribution pattern of species in a warm-temperate conifer-broadleaved-mixed forest in China for sustainably utilizing forest and soils.

PubMed

Song, Houjuan; Xu, Yudan; Hao, Jing; Zhao, Bingqing; Guo, Donggang; Shao, Hongbo

2017-02-01

The maintaining mechanisms and potential ecological processes of species diversity in warm temperate- conifer-broadleaved-mixed forest are far from clear understanding. In this paper, the relative neighborhood density Ω was used to analyze the spatial distribution patterns of 34 species with ≥11 individuals in a warm- temperate-conifer-broadleaved-mixed forest, northern China. Then we used canonical correspondence analysis (CCA) and Torus-translation test (TTT) to explain the distribution of observed species. Our results show that aggregated distribution is the dominant pattern in warm-temperate natural forest and four species regular distribution at the spatial scale >30m. The aggregated percentage and intensity decline with spatial scale, abundance and size classes increasing. Rare species are aggregated more than intermediate and abundant species. These results prove sufficiently the effects existence of scale separation, self-thinning and Janzen-Connell hypothesis. In addition, functional traits (dispersal modes and shade tolerance) also have a significant influence on distribution of species. The results of CCA confirm that slope and convexity are the most important factors affecting the distribution of tree species distribution, elevation and slope of shrub species though the combination of topographic variables only explained 1% of distribution of tree species and 2% of shrub species. Most species don't have habitat preference; however 47.1% (16/34) species including absolutely dominant tree (Pinus tabulaeformis and Quercus wutaishanica) and shrub species (Rosa xanthina) and most other species with important value in the front, are strongly positively or negatively associated with at least one habitat. The valley and ridge are most distinct habitat with association of 12 species in the plot. However, high elevation slope with 257 quadrats is the most extensive habitat with only four species. Therefore, there is obvious evidence that habitat heterogeneity play an important role on shaping spatial distribution of species in warm temperate forest. Our research results provide significant evidence that dispersal limitation and habitat heterogeneity have a contribution jointly to regulating the spatial distribution pattern of species in warm-temperate-forest in China. Copyright © 2016 Elsevier B.V. All rights reserved.

Local influence of south-east France topography and land cover on the distribution and characteristics of intense rainfall cells

NASA Astrophysics Data System (ADS)

Renard, Florent

2017-04-01

The Greater Lyon area is strongly built up, grouping 58 communes and a population of 1.3 million in approximately 500 km2. The flood risk is high as the territory is crossed by two large watercourses and by streams with torrential flow. Floods may also occur in case of runoff after heavy rain or because of a rise in the groundwater level. The whole territory can therefore be affected, and it is necessary to possess in-depth knowledge of the depths, causes and consequences of rainfall to achieve better management of precipitation in urban areas and to reduce flood risk. This study is thus focused on the effects of topography and land cover on the occurrence, intensity and area of intense rainfall cells. They are identified by local radar meteorology (C-band) combined with a processing algorithm running in a geographic information system (GIS) which identified 109,979 weighted mean centres of them in a sample composed of the five most intense rainfall events from 2001 to 2005. First, analysis of spatial distribution at an overall scale is performed, completed by study at a more detailed scale. The results show that the distribution of high-intensity rainfall cells is spread in cluster form. Subsequently, comparison of intense rainfall cells with the topography shows that cell density is closely linked with land slope but that, above all, urbanised zones feature nearly twice as many rainfall cells as farm land or forest, with more intense intensity.

A Heavy Tailed Expectation Maximization Hidden Markov Random Field Model with Applications to Segmentation of MRI

PubMed Central

Castillo-Barnes, Diego; Peis, Ignacio; Martínez-Murcia, Francisco J.; Segovia, Fermín; Illán, Ignacio A.; Górriz, Juan M.; Ramírez, Javier; Salas-Gonzalez, Diego

2017-01-01

A wide range of segmentation approaches assumes that intensity histograms extracted from magnetic resonance images (MRI) have a distribution for each brain tissue that can be modeled by a Gaussian distribution or a mixture of them. Nevertheless, intensity histograms of White Matter and Gray Matter are not symmetric and they exhibit heavy tails. In this work, we present a hidden Markov random field model with expectation maximization (EM-HMRF) modeling the components using the α-stable distribution. The proposed model is a generalization of the widely used EM-HMRF algorithm with Gaussian distributions. We test the α-stable EM-HMRF model in synthetic data and brain MRI data. The proposed methodology presents two main advantages: Firstly, it is more robust to outliers. Secondly, we obtain similar results than using Gaussian when the Gaussian assumption holds. This approach is able to model the spatial dependence between neighboring voxels in tomographic brain MRI. PMID:29209194

Thermal equilibrium and statistical thermometers in special relativity.

PubMed

Cubero, David; Casado-Pascual, Jesús; Dunkel, Jörn; Talkner, Peter; Hänggi, Peter

2007-10-26

There is an intense debate in the recent literature about the correct generalization of Maxwell's velocity distribution in special relativity. The most frequently discussed candidate distributions include the Jüttner function as well as modifications thereof. Here we report results from fully relativistic one-dimensional molecular dynamics simulations that resolve the ambiguity. The numerical evidence unequivocally favors the Jüttner distribution. Moreover, our simulations illustrate that the concept of "thermal equilibrium" extends naturally to special relativity only if a many-particle system is spatially confined. They make evident that "temperature" can be statistically defined and measured in an observer frame independent way.

Analysis of suicide mortality in Brazil: spatial distribution and socioeconomic context.

PubMed

Dantas, Ana P; Azevedo, Ulicélia N de; Nunes, Aryelly D; Amador, Ana E; Marques, Marilane V; Barbosa, Isabelle R

2018-01-01

To perform a spatial analysis of suicide mortality and its correlation with socioeconomic indicators in Brazilian municipalities. This is an ecological study with Brazilian municipalities as a unit of analysis. Data on deaths from suicide and contextual variables were analyzed. The spatial distribution, intensity and significance of the clusters were analyzed with the global Moran index, MoranMap and local indicators of spatial association (LISA), seeking to identify patterns through geostatistical analysis. A total of 50,664 deaths from suicide were registered in Brazil between 2010 and 2014. The average suicide mortality rate in Brazil was 5.23/100,000 population. The Brazilian municipalities presenting the highest rates were Taipas do Tocantins, state of Tocantins (79.68 deaths per 100,000 population), Itaporã, state of Mato Grosso do Sul (75.15 deaths per 100,000 population), Mampituba, state of Rio Grande do Sul (52.98 deaths per 100,000 population), Paranhos, state of Mato Grosso do Sul (52.41 deaths per 100,000 population), and Monjolos, state of Minas Gerais (52.08 deaths per 100,000 population). Although weak spatial autocorrelation was observed for suicide mortality (I = 0.2608), there was a formation of clusters in the South. In the bivariate spatial and classical analysis, no correlation was observed between suicide mortality and contextual variables. Suicide mortality in Brazil presents a weak spatial correlation and low or no spatial relationship with socioeconomic factors.

[Effect of thinning intensities on fruiting regularities of Quercus liaotungensis forests in Huang-long and Qiaoshan mountains.

PubMed

Huang, Cai Zhi; Zhang, Wen Hui; Li, Gang; Yu, Shi Chuan; You, Jian Jian

2016-11-18

In order to clarify the impact of thinning intensities on fruiting regularity of Quercus liaotungensis forests, we took the Q. liaotungensis half-mature forests in Huanglong and Qiaoshan mountains on south of the Loess Plateau as the object of study, which were under close-to-natural management of different thinning intensities (CK, 10%, 20% and 30%). An analysis was made on stand density and percent of seed trees, seed number of sample tree and unit area, seed spatial distributions, seed characteristics of the Q. liaotungensis forests after 5 years of thinning. The results showed that, percent of seed trees, seed number per sample tree and percent of developed seeds of Q. liaotungensis forests increased with the increasing intensity, and showed a pattern of 30%>20%>10%>CK. Seed number per area reached the maximum number under 20% thinning, and showed a pattern of 20%>30%>CK>10%. From the seed spatial distribution in the canopy, the upper accounted for 73.6%, while the lower had 26.4%. The sunny side of canopy layer set relatively the most fruits of 65.8%, shady side only had 34.2%. Under thinning, further improving was geater under lower canopy than under upper canopy and so was on shady side than on sunny side. The seed long diameter, seed short diameter and 1000-seed mass of Q. liaotungensis forests increased with the increasing intensity, which reached the maximum under 30% thinning. 10% thinning did not significantly impact Q. liaotungensis fruiting, the thinning intensity of 20% was most conducive to the seed quantity and quality improvement of Q. liaotungensis, while the thinning intensity of 30% did not improve the fruiting, and lowered the total number of seeds. It was proposed that 20% thinning should be chosen (canopy density of 0.7) to effectively improve fruiting and quality of Q. liaotungensis.

Development effects on private forest management: a critical look at the evidence.

Treesearch

J.D. Kline

2007-01-01

The timber production and ecological effects of forest land development are influenced by both the rate and spatial distribution of forest land development, and how remaining undeveloped forest lands are managed. Regarding effects on management, research conducted in the U.S. South and in Oregon suggests that development can reduce the intensity with which landowners...

Visualization of Nanoplasmonic Coupling to Molecular Orbital in Light Emission Induced by Tunneling Electrons.

PubMed

Yu, Arthur; Li, Shaowei; Wang, Hui; Chen, Siyu; Wu, Ruqian; Ho, W

2018-05-09

The coupling between localized plasmon and molecular orbital in the light emission from a metallic nanocavity has been directly detected and imaged with sub-0.1 nm resolution. The light emission intensity was enhanced when the energy difference between the tunneling electrons and the lowest unoccupied molecular orbital (LUMO) of an azulene molecule matches the energy of a plasmon mode of the nanocavity defined by the Ag-tip and Ag (110) substrate of a scanning tunneling microscope (STM). The spatially resolved image of the light emission intensity matches the spatial distribution of the LUMO obtained by scanning tunneling spectroscopy (STS) and density functional theory (DFT) calculations. Our results highlight the near-field coupling of a molecular orbital to the radiative decay of a plasmonic excitation in a confined nanoscale junction.

Temporal and spatial structure in a daily wildfire-start data set from the western United States (198696)

USGS Publications Warehouse

Bartlein, P.J.; Hostetler, S.W.; Shafer, S.L.; Holman, J.O.; Solomon, A.M.

2008-01-01

The temporal and spatial structure of 332 404 daily fire-start records from the western United States for the period 1986 through 1996 is illustrated using several complimentary visualisation techniques. We supplement maps and time series plots with Hovmo??ller diagrams that reduce the spatial dimensionality of the daily data in order to reveal the underlying space?time structure. The mapped distributions of all lightning- and human-started fires during the 11-year interval show similar first-order patterns that reflect the broad-scale distribution of vegetation across the West and the annual cycle of climate. Lightning-started fires are concentrated in the summer half-year and occur in widespread outbreaks that last a few days and reflect coherent weather-related controls. In contrast, fires started by humans occur throughout the year and tend to be concentrated in regions surrounding large-population centres or intensive-agricultural areas. Although the primary controls of human-started fires are their location relative to burnable fuel and the level of human activity, spatially coherent, weather-related variations in their incidence can also be noted. ?? IAWF 2008.

Spatially Resolved Observations of the Galactic Center Source IRS 21

NASA Astrophysics Data System (ADS)

Tanner, A.; Ghez, A. M.; Morris, M.; Becklin, E. E.; Cotera, A.; Ressler, M.; Werner, M.; Wizinowich, P.

2002-08-01

We present diffraction-limited 2-25 μm images obtained with the W. M. Keck 10 m telescopes that spatially resolve the cool source IRS 21, one of a small group of enigmatic objects in the central parsec of our Galaxy that have eluded classification. Modeled as a Gaussian, the azimuthally averaged intensity profile of IRS 21 has a half-width at half-maximum (HWHM) size of 650+/-80 AU at 2.2 μm and an average HWHM size of 1600+/-200 AU at mid-infrared wavelengths. These large apparent sizes imply an extended distribution of dust. The mid-infrared color map indicates that IRS 21 is a self-luminous source rather than an externally heated dust clump as originally suggested. The spectral energy distribution has distinct near- and mid-infrared components. A simple radiative transfer code, which simultaneously fits the near- and mid-infrared photometry and intensity profiles, supports a model in which the near-infrared radiation is scattered and extincted light from an embedded central source, while the mid-infrared emission is from thermally reradiating silicate dust. We argue that IRS 21 (and by analogy, the other luminous sources along the Northern Arm) is a massive star experiencing rapid mass loss and plowing through the Northern Arm, thereby generating a bow shock, which is spatially resolved in our observations.

What a drag: Quantifying the global impact of chronic bottom trawling on continental shelf sediment

USGS Publications Warehouse

Oberle, Ferdinand K.J.; Storlazzi, Curt; Hanebuth, Till J.J.

2016-01-01

Continental shelves worldwide are subject to intense bottom trawling that causes sediment to be resuspended. The widely used traditional concepts of modern sedimentary transport systems on the shelf rely only on estimates for naturally driven sediment resuspension such as through storm waves, bottom currents, and gravity-driven flows but they overlook a critical anthropogenic factor. The strong influence of bottom trawling on a source-to-sink sediment budget is explored on the NW Iberian shelf. Use of Automated Information System vessel tracking data provides for a high-resolution vessel track reconstruction and the accurate calculation of the spatial distribution of bottom trawling intensity and associated resuspended sediment load. The mean bottom trawling-induced resuspended sediment mass for the NW Iberian shelf is 13.50 Mt yr− 1, which leads to a six-fold increase in off-shelf sediment transport when compared to natural resuspension mechanisms. The source-to-sink budget analysis provides evidence that bottom trawling causes a rapid erosion of the fine sediment on human time scales. Combining global soft sediment distribution data of the shelves with worldwide bottom trawling intensity estimates we show that the bottom trawling-induced resuspended sediment mass amounts to approximately the same mass of all sediment entering the shelves through rivers. Spatial delineations between natural and anthropogenic sediment resuspension areas are presented to aid in marine management questions.

Spatial Distribution of Dopant Incorporation in CdTe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guthrey, Harvey; Moseley, John; Colegrove, Eric

2016-11-21

In this work we use state-of-the-art cathodoluminescence (CL) spectrum imaging that provides spectrum-per-pixel mapping of the CL emission to examine how dopant elements are incorporated into CdTe. Emission spectra and intensity are used to monitor the spatial distribution of additional charge carriers through characteristic variations in the CL emission based on theoretical modeling. Our results show that grain boundaries play a role in the incorporation of dopants in CdTe, whether intrinsic or extrinsic. This type of analysis is crucial for providing feedback to design different processing schedules that optimize dopant incorporation in CdTe photovoltaic material, which has struggled to reachmore » high carrier concentration values. Here, we present results on CdTe films exposed to copper, phosphorus, and intrinsic doping treatments.« less

Proton beam spatial distribution and Bragg peak imaging by photoluminescence of color centers in lithium fluoride crystals at the TOP-IMPLART linear accelerator

NASA Astrophysics Data System (ADS)

Piccinini, M.; Ronsivalle, C.; Ampollini, A.; Bazzano, G.; Picardi, L.; Nenzi, P.; Trinca, E.; Vadrucci, M.; Bonfigli, F.; Nichelatti, E.; Vincenti, M. A.; Montereali, R. M.

2017-11-01

Solid-state radiation detectors based on the photoluminescence of stable point defects in lithium fluoride crystals have been used for advanced diagnostics during the commissioning of the segment up to 27 MeV of the TOP-IMPLART proton linear accelerator for proton therapy applications, under development at ENEA C.R. Frascati, Italy. The LiF detectors high intrinsic spatial resolution and wide dynamic range allow obtaining two-dimensional images of the beam transverse intensity distribution and also identifying the Bragg peak position with micrometric precision by using a conventional optical fluorescence microscope. Results of the proton beam characterization, among which, the estimation of beam energy components and dynamics, are reported and discussed for different operating conditions of the accelerator.

Distribution of photon absorption rates across the rat retina.

PubMed

Williams, T P; Webbers, J P; Giordano, L; Henderson, R P

1998-04-15

1. An investigation into the distribution of light intensity across the rat retina was carried out on excised, intact rat eyes exposed to Ganzfeld illumination from a helium-neon laser (543 nm). 2. Some of the light entering the eyes exits through the sclera where its intensity can be monitored with an optical 'pick-up' that samples the intensity coming from a small region of external sclera and underlying retina. The spatial resolution of the pick-up is such that it samples light that has passed through ca 2 % of the rods in the rat eye. 3. Some of the laser light is absorbed by the rod pigment, rhodopsin, which gradually bleaches. Bleaching in the retina, in turn, causes an exponential increase in intensity emanating from the sclera. By monitoring this intensity increase, we are able to measure two important parameters in a single bleaching run: the local rhodopsin concentration and the local intensity falling on the rods. 4. With an ocular transmission photometer, we have measured both the local intensity and the local rhodopsin concentration across wide regions of rat retina. Both pigmented and albino rats were studied. 5. The distributions of rhodopsin and intensity were both nearly uniform; consequently, the product, (rhodopsin concentration) x (intensity), was similarly nearly equal across the retina. This means that the initial rate of photon absorption is about the same at all retinal locations. 6. Interpreted in terms of photostasis (the regulation of daily photon catch), this means that the rate of photon absorption is about the same in each rod, viz. 14 400 photons absorbed per rod per second. Since this rate of absorption is sufficient to saturate the rod, one possible purpose of photostasis is to maintain the rod system in a saturated state during daylight hours.

Topographic variations of water supply and plant hydraulics in a mountainous forest

NASA Astrophysics Data System (ADS)

Tai, X.; Mackay, D. S.; Ewers, B. E.; Parsekian, A.; Sperry, J.; Beverly, D.; Speckman, H. N.; Ohara, N.; Fantello, N.; Kelleners, T.; Fullhart, A. T.

2017-12-01

How plants respond to variable local water supply in complex soil-topography systems is not clear although critical. This has been attributed to a lack of integrated models that can resolve relevant hydrological and physiological mechanisms and intensive field monitoring to inform/evaluate such a model. This research addresses these knowledge gaps by leveraging a newly developed distributed plant hydraulics model, ParFlow-TREES, and detailed geophysical and physiological measurements. Observations of sap flow, leaf water potentials, micrometeorology, and electrical resistivity tomography (ERT) are combined with the model to examine the key mechanisms affecting the spatial distribution of soil water and tree water stress. Modeling results showed higher soil water condition at bottom of the hillslope on average, corroborating the ERT-derived soil moisture observations. Hydraulic traits are critical to capture the sap flux dynamics of species with contrasting leaf water potential regulation strategies and heterogeneous soil drying at different hillslope positions. These results suggested the integrated effect of topography and plants on the evolvement of soil moisture distribution. Furthermore, sensitivity analysis demonstrated the importance of using distributed observations to validate/calibrate distributed models. Focusing on lumped variables or only one particular variable might give misleading conclusions. Co-located observations improve the characterization of plant traits and local living environment, providing key information needed as a first step in resolving the form and function of the critical zone from bedrock to atmosphere. We will discuss the broader implications and potential applications of this intensive data-model comparison at other sites and greater spatial extent.

Measuring topology of low-intensity DNA methylation sites for high-throughput assessment of epigenetic drug-induced effects in cancer cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gertych, Arkadiusz, E-mail: gertycha@cshs.org; Bioinformatics, Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA; Farkas, Daniel L., E-mail: dlfarkas@gmail.com

2010-11-15

Epigenetic anti-cancer drugs with demethylating effects have shown to alter genome organization in mammalian cell nuclei. The interest in the development of novel epigenetic drugs has increased the demand for cell-based assays to evaluate drug performance in pre-clinical studies. An imaging-based cytometrical approach that can measure demethylation effects as changes in the spatial nuclear distributions of methylated cytosine and global DNA in cancer cells is introduced in this paper. The cells were studied by immunofluorescence with a specific antibody against 5-methylcytosine (MeC), and 4,6-diamidino-2-phenylindole (DAPI) for delineation of methylated sites and global DNA in nuclei. In the preprocessing step themore » segmentation of nuclei in three-dimensional images (3-D) is followed by an automated assessment of nuclear DAPI/MeC patterns to exclude dissimilar entities. Next, low-intensity MeC (LIM) and low-intensity DNA (LID) sites of similar nuclei are localized and processed to obtain specific nuclear density profiles. These profiles sampled at half of the total nuclear volume yielded two parameters: LIM{sub 0.5} and LID{sub 0.5}. The analysis shows that zebularine and 5-azacytidine-the two tested epigenetic drugs introduce changes in the spatial distribution of low-intensity DNA and MeC signals. LIM{sub 0.5} and LID{sub 0.5} were significantly different (p < 0.001) in 5-azacytidine treated (n = 660) and zebularine treated (n = 496) vs. untreated (n = 649) DU145 human prostate cancer cells. In the latter case the LIM sites were predominantly found at the nuclear border, whereas treated populations showed different degrees of increase in LIMs towards the interior nuclear space, in which a large portion of heterochromatin is located. The cell-by-cell evaluation of changes in the spatial reorganization of MeC/DAPI signals revealed that zebularine is a more gentle demethylating agent than 5-azacytidine. Measuring changes in the topology of low-intensity sites can potentially be a valuable component in the high-throughput assessment of demethylation and risk of chromatin reorganization in epigenetic-drug screening tasks.« less

Solution of multi-element LED light sources development automation problem

NASA Astrophysics Data System (ADS)

Chertov, Aleksandr N.; Gorbunova, Elena V.; Korotaev, Valery V.; Peretyagin, Vladimir S.

2014-09-01

The intensive development of LED technologies resulted in the creation of multicomponent light sources in the form of controlled illumination devices based on usage of mentioned LED technologies. These light sources are used in different areas of production (for example, in the food industry for sorting products or in the textile industry for quality control, etc.). The use of LED lighting products in the devices used in specialized lighting, became possible due to wide range of colors of light, LED structures (which determines the direction of radiation, the spatial distribution and intensity of the radiation, electrical, heat, power and other characteristics), and of course, the possibility of obtaining any shade in a wide dynamic range of brightness values. LED-based lighting devices are notable for the diversity of parameters and characteristics, such as color radiation, location and number of emitters, etc. Although LED technologies have several advantages, however, they require more attention if you need to ensure a certain character of illumination distribution and/or distribution of the color picture at a predetermined distance (for example, at flat surface, work zone, area of analysis or observation). This paper presents software designed for the development of the multicomponent LED light sources. The possibility of obtaining the desired color and energy distribution at the zone of analysis by specifying the spatial parameters of the created multicomponent light source and using of real power, spectral and color parameters and characteristics of the LEDs is shown as well.

Robust generative asymmetric GMM for brain MR image segmentation.

PubMed

Ji, Zexuan; Xia, Yong; Zheng, Yuhui

2017-11-01

Accurate segmentation of brain tissues from magnetic resonance (MR) images based on the unsupervised statistical models such as Gaussian mixture model (GMM) has been widely studied during last decades. However, most GMM based segmentation methods suffer from limited accuracy due to the influences of noise and intensity inhomogeneity in brain MR images. To further improve the accuracy for brain MR image segmentation, this paper presents a Robust Generative Asymmetric GMM (RGAGMM) for simultaneous brain MR image segmentation and intensity inhomogeneity correction. First, we develop an asymmetric distribution to fit the data shapes, and thus construct a spatial constrained asymmetric model. Then, we incorporate two pseudo-likelihood quantities and bias field estimation into the model's log-likelihood, aiming to exploit the neighboring priors of within-cluster and between-cluster and to alleviate the impact of intensity inhomogeneity, respectively. Finally, an expectation maximization algorithm is derived to iteratively maximize the approximation of the data log-likelihood function to overcome the intensity inhomogeneity in the image and segment the brain MR images simultaneously. To demonstrate the performances of the proposed algorithm, we first applied the proposed algorithm to a synthetic brain MR image to show the intermediate illustrations and the estimated distribution of the proposed algorithm. The next group of experiments is carried out in clinical 3T-weighted brain MR images which contain quite serious intensity inhomogeneity and noise. Then we quantitatively compare our algorithm to state-of-the-art segmentation approaches by using Dice coefficient (DC) on benchmark images obtained from IBSR and BrainWeb with different level of noise and intensity inhomogeneity. The comparison results on various brain MR images demonstrate the superior performances of the proposed algorithm in dealing with the noise and intensity inhomogeneity. In this paper, the RGAGMM algorithm is proposed which can simply and efficiently incorporate spatial constraints into an EM framework to simultaneously segment brain MR images and estimate the intensity inhomogeneity. The proposed algorithm is flexible to fit the data shapes, and can simultaneously overcome the influence of noise and intensity inhomogeneity, and hence is capable of improving over 5% segmentation accuracy comparing with several state-of-the-art algorithms. Copyright © 2017 Elsevier B.V. All rights reserved.

Spectroscopic Imaging of NIR to Visible Upconversion from NaYF4:Yb3+, Er3+ Nanoparticles on Au Nano-cavity Arrays

NASA Astrophysics Data System (ADS)

Fisher, Jon; Zhao, Bo; Lin, Cuikun; Berry, Mary; May, P. Stanley; Smith, Steve

2015-03-01

We use spectroscopic imaging to assess the spatial variations in upconversion luminescence from NaYF4:Er3+,Yb3+ nanoparticles embedded in PMMA on Au nano-cavity arrays. The nano-cavity arrays support a surface plasmon (SP) resonance at 980nm, coincident with the peak absorption of the Yb3+ sensitizer. Spatially-resolved upconversion spectra show a 30X to 3X luminescence intensity enhancement on the nano-cavity array compared to the nearby smooth Au surface, corresponding to excitation intensities from 1 W/cm2 to 300kW/cm2. Our analysis shows the power dependent enhancement in upconversion luminescence can be almost entirely accounted for by a constant shift in the effective excitation intensity, which is maintained over five orders of magnitude variation in excitation intensity. The variations in upconversion luminescence enhancement with power are modeled by a 3-level-system near the saturation limit, and by simultaneous solution of a system of coupled nonlinear differential equations, both analyses agree well with the experiments. Analysis of the statistical distribution of emission intensities in the spectroscopic images on and off the nano-cavity arrays provides an estimate of the average enhancement factor independent of fluctuations in nano-particle density. Funding provided by NSF Award # 0903685 (IGERT).

Diagnosis of warm dense conditions in foil targets heated by intense femtosecond laser pulses using Kα imaging spectroscopy

DOE PAGES

Bae, L. J.; Zastrau, U.; Chung, H. -K.; ...

2018-03-01

Warm dense conditions in titanium foils irradiated with intense femtosecond laser pulses are diagnosed using an x-ray imaging spectroscopy technique. The line shapes of radially resolved titanium Kα spectra are measured with a toroidally bent GaAs crystal and an x-ray charge-coupled device. Measured spectra are compared with the K-shell emissions modeled using an atomic kinetics – spectroscopy simulation code. Kα line shapes are strongly affected by warm (5-40 eV) bulk electron temperatures and imply multiple temperature distributions in the targets. Finally, the spatial distribution of temperature is dependent on the target thickness, and a thin target shows an advantage tomore » generate uniform warm dense conditions in a large area.« less

Diagnosis of warm dense conditions in foil targets heated by intense femtosecond laser pulses using Kα imaging spectroscopy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bae, L. J.; Zastrau, U.; Chung, H. -K.

Warm dense conditions in titanium foils irradiated with intense femtosecond laser pulses are diagnosed using an x-ray imaging spectroscopy technique. The line shapes of radially resolved titanium Kα spectra are measured with a toroidally bent GaAs crystal and an x-ray charge-coupled device. Measured spectra are compared with the K-shell emissions modeled using an atomic kinetics – spectroscopy simulation code. Kα line shapes are strongly affected by warm (5-40 eV) bulk electron temperatures and imply multiple temperature distributions in the targets. Finally, the spatial distribution of temperature is dependent on the target thickness, and a thin target shows an advantage tomore » generate uniform warm dense conditions in a large area.« less

Generalized Kapchinskij-Vladimirskij Distribution and Beam Matrix for Phase-Space Manipulations of High-Intensity Beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chung, Moses; Qin, Hong; Davidson, Ronald C.

In an uncoupled linear lattice system, the Kapchinskij-Vladimirskij (KV) distribution formulated on the basis of the single-particle Courant-Snyder invariants has served as a fundamental theoretical basis for the analyses of the equilibrium, stability, and transport properties of high-intensity beams for the past several decades. Recent applications of high-intensity beams, however, require beam phase-space manipulations by intentionally introducing strong coupling. Here in this Letter, we report the full generalization of the KV model by including all of the linear (both external and space-charge) coupling forces, beam energy variations, and arbitrary emittance partition, which all form essential elements for phase-space manipulations. Themore » new generalized KV model yields spatially uniform density profiles and corresponding linear self-field forces as desired. Finally, the corresponding matrix envelope equations and beam matrix for the generalized KV model provide important new theoretical tools for the detailed design and analysis of high-intensity beam manipulations, for which previous theoretical models are not easily applicable.« less

Intensity dependence of focused ultrasound lesion position

NASA Astrophysics Data System (ADS)

Meaney, Paul M.; Cahill, Mark D.; ter Haar, Gail R.

1998-04-01

Knowledge of the spatial distribution of intensity loss from an ultrasonic beam is critical to predicting lesion formation in focused ultrasound surgery. To date most models have used linear propagation models to predict the intensity profiles needed to compute the temporally varying temperature distributions. These can be used to compute thermal dose contours that can in turn be used to predict the extent of thermal damage. However, these simulations fail to adequately describe the abnormal lesion formation behavior observed for in vitro experiments in cases where the transducer drive levels are varied over a wide range. For these experiments, the extent of thermal damage has been observed to move significantly closer to the transducer with increasing transducer drive levels than would be predicted using linear propagation models. The simulations described herein, utilize the KZK (Khokhlov-Zabolotskaya-Kuznetsov) nonlinear propagation model with the parabolic approximation for highly focused ultrasound waves, to demonstrate that the positions of the peak intensity and the lesion do indeed move closer to the transducer. This illustrates that for accurate modeling of heating during FUS, nonlinear effects must be considered.

Intense ion beam diagnostics for ICF

NASA Astrophysics Data System (ADS)

Yasuike, K.; Cuneo, M. E.; Wenger, D. F.; Bailey, J. E.; Hanson, D. L.; Mehlhorn, T. A.; Imasaki, K.; Nakai, S.; Mima, K.

1998-11-01

Development of diagnostic methods for high intensity ion beams for ICF is crucial for understanding the ion diode physics. At Osaka University, an arrayed pinhole camera (APC) diagnostic method had been developed to measure the proton beams with an energy of 1 MeV and a J_i. of 100 A/cm^2. on Reiden-SHVS. The APC measures spatial distributions of the beam divergence in r and θ drection and the intensity distribution. An ion image detector capable to acquire a whole temporal evolution within a shot is necessary to measure the higher intensity beams. A fast scintillator with photo-multiplier tubes has been chosen as the image detector. The detector is being tested on a single pinhole camera using a Lithium beam with a particle energy of 5 MeV, a J_i. of 0.5-1 kA/cm^2. and duration of 50 ns, which are very close to the parameters required from ICF, on the SABRE at Sandia National Labs. We will present the diagnostic design and preliminary experiments from SABRE and also present the experimental results from Reiden-SHVS.

Generalized Kapchinskij-Vladimirskij Distribution and Beam Matrix for Phase-Space Manipulations of High-Intensity Beams

DOE PAGES

Chung, Moses; Qin, Hong; Davidson, Ronald C.; ...

2016-11-23

In an uncoupled linear lattice system, the Kapchinskij-Vladimirskij (KV) distribution formulated on the basis of the single-particle Courant-Snyder invariants has served as a fundamental theoretical basis for the analyses of the equilibrium, stability, and transport properties of high-intensity beams for the past several decades. Recent applications of high-intensity beams, however, require beam phase-space manipulations by intentionally introducing strong coupling. Here in this Letter, we report the full generalization of the KV model by including all of the linear (both external and space-charge) coupling forces, beam energy variations, and arbitrary emittance partition, which all form essential elements for phase-space manipulations. Themore » new generalized KV model yields spatially uniform density profiles and corresponding linear self-field forces as desired. Finally, the corresponding matrix envelope equations and beam matrix for the generalized KV model provide important new theoretical tools for the detailed design and analysis of high-intensity beam manipulations, for which previous theoretical models are not easily applicable.« less

Spectral characterization of Dictyostelium autofluorescence.

PubMed

Engel, Ruchira; Van Haastert, Peter J M; Visser, Antonie J W G

2006-03-01

Dictyostelium discoideum is used extensively as a model organism for the study of chemotaxis. In recent years, an increasing number of studies of Dictyostelium chemotaxis have made use of fluorescence-based techniques. One of the major factors that can interfere with the application of these techniques in cells is the cellular autofluorescence. In this study, the spectral properties of Dictyostelium autofluorescence have been characterized using fluorescence microscopy. Whole cell autofluorescence spectra obtained using spectral imaging microscopy show that Dictyostelium autofluorescence covers a wavelength range from approximately 500 to 650 nm with a maximum at approximately 510 nm, and thus, potentially interferes with measurements of green fluorescent protein (GFP) fusion proteins with fluorescence microscopy techniques. Further characterization of the spatial distribution, intensity, and brightness of the autofluorescence was performed with fluorescence confocal microscopy and fluorescence fluctuation spectroscopy (FFS). The autofluorescence in both chemotaxing and nonchemotaxing cells is localized in discrete areas. The high intensity seen in cells incubated in the growth medium HG5 reduces by around 50% when incubated in buffer, and can be further reduced by around 85% by photobleaching cells for 5-7 s. The average intensity and spatial distribution of the autofluorescence do not change with long incubations in the buffer. The cellular autofluorescence has a seven times lower molecular brightness than eGFP. The influence of autofluorescence in FFS measurements can be minimized by incubating cells in buffer during the measurements, pre-bleaching, and making use of low excitation intensities. The results obtained in this study thus offer guidelines to the design of future fluorescence studies of Dictyostelium. Microsc. Res. Tech. 69:168-174, 2006. (c) 2006 Wiley-Liss, Inc.

Spatial Interpolation of Rain-field Dynamic Time-Space Evolution in Hong Kong

NASA Astrophysics Data System (ADS)

Liu, P.; Tung, Y. K.

2017-12-01

Accurate and reliable measurement and prediction of spatial and temporal distribution of rain-field over a wide range of scales are important topics in hydrologic investigations. In this study, geostatistical treatment of precipitation field is adopted. To estimate the rainfall intensity over a study domain with the sample values and the spatial structure from the radar data, the cumulative distribution functions (CDFs) at all unsampled locations were estimated. Indicator Kriging (IK) was used to estimate the exceedance probabilities for different pre-selected cutoff levels and a procedure was implemented for interpolating CDF values between the thresholds that were derived from the IK. Different interpolation schemes of the CDF were proposed and their influences on the performance were also investigated. The performance measures and visual comparison between the observed rain-field and the IK-based estimation suggested that the proposed method can provide fine results of estimation of indicator variables and is capable of producing realistic image.

A 64-pixel NbTiN superconducting nanowire single-photon detector array for spatially resolved photon detection.

PubMed

Miki, Shigehito; Yamashita, Taro; Wang, Zhen; Terai, Hirotaka

2014-04-07

We present the characterization of two-dimensionally arranged 64-pixel NbTiN superconducting nanowire single-photon detector (SSPD) array for spatially resolved photon detection. NbTiN films deposited on thermally oxidized Si substrates enabled the high-yield production of high-quality SSPD pixels, and all 64 SSPD pixels showed uniform superconducting characteristics within the small range of 7.19-7.23 K of superconducting transition temperature and 15.8-17.8 μA of superconducting switching current. Furthermore, all of the pixels showed single-photon sensitivity, and 60 of the 64 pixels showed a pulse generation probability higher than 90% after photon absorption. As a result of light irradiation from the single-mode optical fiber at different distances between the fiber tip and the active area, the variations of system detection efficiency (SDE) in each pixel showed reasonable Gaussian distribution to represent the spatial distributions of photon flux intensity.

Research on spatial difference in the effecting factors of the urban flow

NASA Astrophysics Data System (ADS)

Liang, Jian; Li, Feixue; Xu, Jiangang; Li, Manchun

2007-06-01

Urban flow is a phenomenon of the interaction and relation between the cities in the region based on the transport network and urban synthetic strength. And, because of the difference in traffic conditions and the level of economic development in different city, the intensity of the urban flow of each city is different and the primary effecting factor is dissimilar. The traditional analysis on the effecting factors of urban flow concerns the background of the entire region as a whole entity, which would be too vague and ignore the difference in the effecting factors of different cities as well as the micro differences and spatial non-stationarity in the dominant factor. The research on spatial difference in the effecting factors of the urban flow in this paper focused on the analysis of the diverse effecting factors of urban flow caused by the regional disparity; found out the primary factors; and analyzed the spatial characteristics of effecting factors using GIS. We established a mathematical model, which was applied to the urban agglomeration of the Yangtze River Delta, the intensity of the urban flow of every city in this district was figured and the regression model was constructed. The principal effecting factor of the urban flow of every city and its characteristic of the spatial distribution was analyzed. we summarized the effecting factors of the urban flow is an indication of the persistence of spatial difference among Yangtze River Delta, and the spatial pattern of it was investigated.

A simple daily soil-water balance model for estimating the spatial and temporal distribution of groundwater recharge in temperate humid areas

USGS Publications Warehouse

Dripps, W.R.; Bradbury, K.R.

2007-01-01

Quantifying the spatial and temporal distribution of natural groundwater recharge is usually a prerequisite for effective groundwater modeling and management. As flow models become increasingly utilized for management decisions, there is an increased need for simple, practical methods to delineate recharge zones and quantify recharge rates. Existing models for estimating recharge distributions are data intensive, require extensive parameterization, and take a significant investment of time in order to establish. The Wisconsin Geological and Natural History Survey (WGNHS) has developed a simple daily soil-water balance (SWB) model that uses readily available soil, land cover, topographic, and climatic data in conjunction with a geographic information system (GIS) to estimate the temporal and spatial distribution of groundwater recharge at the watershed scale for temperate humid areas. To demonstrate the methodology and the applicability and performance of the model, two case studies are presented: one for the forested Trout Lake watershed of north central Wisconsin, USA and the other for the urban-agricultural Pheasant Branch Creek watershed of south central Wisconsin, USA. Overall, the SWB model performs well and presents modelers and planners with a practical tool for providing recharge estimates for modeling and water resource planning purposes in humid areas. ?? Springer-Verlag 2007.

Grain-size analysis and sediment dynamics of hurricane-induced event beds in a coastal New England pond

NASA Astrophysics Data System (ADS)

Castagno, K. A.; Ruehr, S. A.; Donnelly, J. P.; Woodruff, J. D.

2017-12-01

Coastal populations have grown increasingly susceptible to the impacts of tropical cyclone events as they grow in size, wealth, and infrastructure. Changes in tropical cyclone frequency and intensity, augmented by a changing climate, pose an increasing threat of property damage and loss of life. Reconstructions of intense-hurricane landfalls from a series of southeastern New England sediment cores identify a series of events spanning the past 2,000 years. Though the frequency of these landfalls is well constrained, the intensity of these storms, particularly those for which no historical record exists, is not. This study analyzes the grain-size distribution of major storm event beds along a transect of sediment cores from a kettle pond in Falmouth, MA. The grain-size distribution of each event is determined using an image processing, size, and shape analyzer. The depositional patterns and changes in grain-size distribution in these fine-grained systems may both spatially and temporally reveal characteristics of both storm intensity and the nature of sediment deposition. An inverse-modeling technique using this kind of grain-size analysis to determine past storm intensity has been explored in back-barrier lagoon systems in the Caribbean, but limited research has assessed its utility to assess deposits from back-barrier ponds in the northeastern United States. Increases in hurricane intensity may be closely tied to increases in sea surface temperature. As such, research into these prehistoric intervals of increased frequency and/or intensity provides important insight into the current and future hurricane risks facing coastal communities in New England.

The spatial distribution of threats to plant species with extremely small populations

NASA Astrophysics Data System (ADS)

Wang, Chunjing; Zhang, Jing; Wan, Jizhong; Qu, Hong; Mu, Xianyun; Zhang, Zhixiang

2017-03-01

Many biological conservationists take actions to conserve plant species with extremely small populations (PSESP) in China; however, there have been few studies on the spatial distribution of threats to PSESP. Hence, we selected distribution data of PSESP and made a map of the spatial distribution of threats to PSESP in China. First, we used the weight assignment method to evaluate the threat risk to PSESP at both country and county scales. Second, we used a geographic information system to map the spatial distribution of threats to PSESP, and explored the threat factors based on linear regression analysis. Finally, we suggested some effective conservation options. We found that the PSESP with high values of protection, such as the plants with high scientific research values and ornamental plants, were threatened by over-exploitation and utilization, habitat fragmentation, and a small sized wild population in broad-leaved forests and bush fallows. We also identified some risk hotspots for PSESP in China. Regions with low elevation should be given priority for ex- and in-situ conservation. Moreover, climate change should be considered for conservation of PSESP. To avoid intensive over-exploitation or utilization and habitat fragmentation, in-situ conservation should be practiced in regions with high temperatures and low temperature seasonality, particularly in the high risk hotspots for PSESP that we proposed. Ex-situ conservation should be applied in these same regions, and over-exploitation and utilization of natural resources should be prevented. It is our goal to apply the concept of PSESP to the global scale in the future.

Environmental determinants of the spatial distribution of Echinococcus multilocularis in Hungary.

PubMed

Tolnai, Z; Széll, Z; Sréter, T

2013-12-06

Human alveolar echinococcosis, caused by the metacestode stage of Echinococcus multilocularis, is one of the most pathogenic zoonoses in the temperate and arctic region of the Northern Hemisphere. To investigate the spatial distribution of E. multilocularis and the factors influencing this distribution in the recently identified endemic area of Hungary, 1612 red fox (Vulpes vulpes) carcasses were randomly collected from the whole Hungarian territory from November 2008 to February 2009 and from November 2012 to February 2013. The topographic positions of foxes were recorded in geographic information system database. The digitized home ranges and the vector data were used to calculate the altitude, mean annual temperature, annual precipitation, soil water retention, soil permeability, areas of land cover types and the presence and buffer zone of permanent water bodies within the fox territories. The intestinal mucosa from all the foxes was tested by sedimentation and counting technique. Multiple regression analysis was performed with environmental parameter values and E. multilocularis counts. The spatial distribution of the parasite was clumped. Based on statistical analysis, mean annual temperature and annual precipitation were the major determinants of the spatial distribution of E. multilocularis in Hungary. It can be attributed to the sensitivity of E. multilocularis eggs to high temperatures and desiccation. Although spreading and emergence of the parasite was observed in Hungary before 2009, the prevalence and intensity of infection did not change significantly between the two collection periods. It can be explained by the considerably lower annual precipitation before the second collection period. Copyright © 2013 Elsevier B.V. All rights reserved.

Combining binary decision tree and geostatistical methods to estimate snow distribution in a mountain watershed

USGS Publications Warehouse

Balk, Benjamin; Elder, Kelly

2000-01-01

We model the spatial distribution of snow across a mountain basin using an approach that combines binary decision tree and geostatistical techniques. In April 1997 and 1998, intensive snow surveys were conducted in the 6.9‐km2 Loch Vale watershed (LVWS), Rocky Mountain National Park, Colorado. Binary decision trees were used to model the large‐scale variations in snow depth, while the small‐scale variations were modeled through kriging interpolation methods. Binary decision trees related depth to the physically based independent variables of net solar radiation, elevation, slope, and vegetation cover type. These decision tree models explained 54–65% of the observed variance in the depth measurements. The tree‐based modeled depths were then subtracted from the measured depths, and the resulting residuals were spatially distributed across LVWS through kriging techniques. The kriged estimates of the residuals were added to the tree‐based modeled depths to produce a combined depth model. The combined depth estimates explained 60–85% of the variance in the measured depths. Snow densities were mapped across LVWS using regression analysis. Snow‐covered area was determined from high‐resolution aerial photographs. Combining the modeled depths and densities with a snow cover map produced estimates of the spatial distribution of snow water equivalence (SWE). This modeling approach offers improvement over previous methods of estimating SWE distribution in mountain basins.

Linking Spatial Structure and Community-Level Biotic Interactions through Cooccurrence and Time Series Modeling of the Human Intestinal Microbiota.

PubMed

de Muinck, Eric J; Lundin, Knut E A; Trosvik, Pål

2017-01-01

The gastrointestinal (GI) microbiome is a densely populated ecosystem where dynamics are determined by interactions between microbial community members, as well as host factors. The spatial organization of this system is thought to be important in human health, yet this aspect of our resident microbiome is still poorly understood. In this study, we report significant spatial structure of the GI microbiota, and we identify general categories of spatial patterning in the distribution of microbial taxa along a healthy human GI tract. We further estimate the biotic interaction structure in the GI microbiota, both through time series and cooccurrence modeling of microbial community data derived from a large number of sequentially collected fecal samples. Comparison of these two approaches showed that species pairs involved in significant negative interactions had strong positive contemporaneous correlations and vice versa, while for species pairs without significant interactions, contemporaneous correlations were distributed around zero. We observed similar patterns when comparing these models to the spatial correlations between taxa identified in the adherent microbiota. This suggests that colocalization of microbial taxon pairs, and thus the spatial organization of the GI microbiota, is driven, at least in part, by direct or indirect biotic interactions. Thus, our study can provide a basis for an ecological interpretation of the biogeography of the human gut. IMPORTANCE The human gut microbiome is the subject of intense study due to its importance in health and disease. The majority of these studies have been based on the analysis of feces. However, little is known about how the microbial composition in fecal samples relates to the spatial distribution of microbial taxa along the gastrointestinal tract. By characterizing the microbial content both in intestinal tissue samples and in fecal samples obtained daily, we provide a conceptual framework for how the spatial structure relates to biotic interactions on the community level. We further describe general categories of spatial distribution patterns and identify taxa conforming to these categories. To our knowledge, this is the first study combining spatial and temporal analyses of the human gut microbiome. This type of analysis can be used for identifying candidate probiotics and designing strategies for clinical intervention.

Edge-Preserving Image Smoothing Constraint in Multivariate Curve Resolution-Alternating Least Squares (MCR-ALS) of Hyperspectral Data.

PubMed

Hugelier, Siewert; Vitale, Raffaele; Ruckebusch, Cyril

2018-03-01

This article explores smoothing with edge-preserving properties as a spatial constraint for the resolution of hyperspectral images with multivariate curve resolution-alternating least squares (MCR-ALS). For each constrained component image (distribution map), irrelevant spatial details and noise are smoothed applying an L 1 - or L 0 -norm penalized least squares regression, highlighting in this way big changes in intensity of adjacent pixels. The feasibility of the constraint is demonstrated on three different case studies, in which the objects under investigation are spatially clearly defined, but have significant spectral overlap. This spectral overlap is detrimental for obtaining a good resolution and additional spatial information should be provided. The final results show that the spatial constraint enables better image (map) abstraction, artifact removal, and better interpretation of the results obtained, compared to a classical MCR-ALS analysis of hyperspectral images.

Mapping the spatial patterns of field traffic and traffic intensity to predict soil compaction risks at the field scale

NASA Astrophysics Data System (ADS)

Duttmann, Rainer; Kuhwald, Michael; Nolde, Michael

2015-04-01

Soil compaction is one of the main threats to cropland soils in present days. In contrast to easily visible phenomena of soil degradation, soil compaction, however, is obscured by other signals such as reduced crop yield, delayed crop growth, and the ponding of water, which makes it difficult to recognize and locate areas impacted by soil compaction directly. Although it is known that trafficking intensity is a key factor for soil compaction, until today only modest work has been concerned with the mapping of the spatially distributed patterns of field traffic and with the visual representation of the loads and pressures applied by farm traffic within single fields. A promising method for for spatial detection and mapping of soil compaction risks of individual fields is to process dGPS data, collected from vehicle-mounted GPS receivers and to compare the soil stress induced by farm machinery to the load bearing capacity derived from given soil map data. The application of position-based machinery data enables the mapping of vehicle movements over time as well as the assessment of trafficking intensity. It also facilitates the calculation of the trafficked area and the modeling of the loads and pressures applied to soil by individual vehicles. This paper focuses on the modeling and mapping of the spatial patterns of traffic intensity in silage maize fields during harvest, considering the spatio-temporal changes in wheel load and ground contact pressure along the loading sections. In addition to scenarios calculated for varying mechanical soil strengths, an example for visualizing the three-dimensional stress propagation inside the soil will be given, using the Visualization Toolkit (VTK) to construct 2D or 3D maps supporting to decision making due to sustainable field traffic management.

Spatial relationship with the grazing pressure and alpine grassland degradation base on the GPS tracing experiment: a case study in the source region of Yellow River

NASA Astrophysics Data System (ADS)

Liu, L.; Zhang, Y.

2014-12-01

It is hard to distinguish the affects from the human activities and climate change on the grassland degradation, especially to quantification the human activities. Grazing is the main kind of human activities on the alpine grassland. To investigate the relationship of the grazing activities and grassland degradation will help the understanding of the effects of human impacts. A GPS tracing experiment was designed to tracing the activities of the Yaks. The spatial distribution of the grazing pressure was simulated under Geographic Information System. The biomass distribution and grazing pressure was compared to judge the distribution of overgrazing. The main research results are: (1) The tracing experiment could record the track of the Yaks very well, and it could be a good tool for the quantification research of grazing pressure. (2) The grazing activities have good relationship with vegetation, residents and landform. The worse vegetation is, the grazing time is longer and the radius is bigger. The closer to the residents, the grazing intensive is higher. The grazing route is influenced by the landform. Usually the herds would like to choose the least cost way. And the grazing intensive is higher in sunny slope. (3) The grazing probability is higher while the elevation is lower and the vegetation is better. The numbers of livestock of different villages determine the spatial distribution of the grazing pressure but it has very big heterogeneity in the same village. It seems the forage is enough in the research area since the available biomass is about 1190058t and the total demand is only 603700t. But because of the heterogeneity of the grazing pressure, there are still overgrazing in some villages. The area of overgrazing is 6 percent in the winter rangeland and 11 percent in summer rangeland. It is important to take care of the spatial heterogeneity of the grazing pressure and grass production in the management of the grassland ecosystem. It should improve the calculation method of the stock capacity to avoid the overrating of it. To arrange the livestock reasonably is the guarantee of the sustainable development in this region.

A Bayesian kriging approach for blending satellite and ground precipitation observations

USGS Publications Warehouse

Verdin, Andrew P.; Rajagopalan, Balaji; Kleiber, William; Funk, Christopher C.

2015-01-01

Drought and flood management practices require accurate estimates of precipitation. Gauge observations, however, are often sparse in regions with complicated terrain, clustered in valleys, and of poor quality. Consequently, the spatial extent of wet events is poorly represented. Satellite-derived precipitation data are an attractive alternative, though they tend to underestimate the magnitude of wet events due to their dependency on retrieval algorithms and the indirect relationship between satellite infrared observations and precipitation intensities. Here we offer a Bayesian kriging approach for blending precipitation gauge data and the Climate Hazards Group Infrared Precipitation satellite-derived precipitation estimates for Central America, Colombia, and Venezuela. First, the gauge observations are modeled as a linear function of satellite-derived estimates and any number of other variables—for this research we include elevation. Prior distributions are defined for all model parameters and the posterior distributions are obtained simultaneously via Markov chain Monte Carlo sampling. The posterior distributions of these parameters are required for spatial estimation, and thus are obtained prior to implementing the spatial kriging model. This functional framework is applied to model parameters obtained by sampling from the posterior distributions, and the residuals of the linear model are subject to a spatial kriging model. Consequently, the posterior distributions and uncertainties of the blended precipitation estimates are obtained. We demonstrate this method by applying it to pentadal and monthly total precipitation fields during 2009. The model's performance and its inherent ability to capture wet events are investigated. We show that this blending method significantly improves upon the satellite-derived estimates and is also competitive in its ability to represent wet events. This procedure also provides a means to estimate a full conditional distribution of the “true” observed precipitation value at each grid cell.

Variations in optical coherence tomography resolution and uniformity: a multi-system performance comparison

PubMed Central

Fouad, Anthony; Pfefer, T. Joshua; Chen, Chao-Wei; Gong, Wei; Agrawal, Anant; Tomlins, Peter H.; Woolliams, Peter D.; Drezek, Rebekah A.; Chen, Yu

2014-01-01

Point spread function (PSF) phantoms based on unstructured distributions of sub-resolution particles in a transparent matrix have been demonstrated as a useful tool for evaluating resolution and its spatial variation across image volumes in optical coherence tomography (OCT) systems. Measurements based on PSF phantoms have the potential to become a standard test method for consistent, objective and quantitative inter-comparison of OCT system performance. Towards this end, we have evaluated three PSF phantoms and investigated their ability to compare the performance of four OCT systems. The phantoms are based on 260-nm-diameter gold nanoshells, 400-nm-diameter iron oxide particles and 1.5-micron-diameter silica particles. The OCT systems included spectral-domain and swept source systems in free-beam geometries as well as a time-domain system in both free-beam and fiberoptic probe geometries. Results indicated that iron oxide particles and gold nanoshells were most effective for measuring spatial variations in the magnitude and shape of PSFs across the image volume. The intensity of individual particles was also used to evaluate spatial variations in signal intensity uniformity. Significant system-to-system differences in resolution and signal intensity and their spatial variation were readily quantified. The phantoms proved useful for identification and characterization of irregularities such as astigmatism. Our multi-system results provide evidence of the practical utility of PSF-phantom-based test methods for quantitative inter-comparison of OCT system resolution and signal uniformity. PMID:25071949

Influence of alternative silvicultural treatments on spatial variability in light in central hardwood stands on the Cumberland Plateau

Treesearch

Stephen F. Grayson; David S. Buckley; Jason G. Henning; Callie J. Schweitzer; Stacy L. Clark

2011-01-01

Effective oak silvicultural treatments allow light to reach the forest floor with sufficient intensity and duration to enable establishment, growth, and development of preferred species. Although it is intuitive that increases in light will accompany various levels of canopy removal, specific amounts and the distribution of light resulting from different silvicultural...

Spatially resolved density and ionization measurements of shocked foams using x-ray fluorescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacDonald, M. J.; Keiter, P. A.; Montgomery, D. S.

2016-09-28

We present experiments at the Trident laser facility demonstrating the use of x-ray fluorescence (XRF) to simultaneously measure density, ionization state populations, and electron temperature in shocked foams. An imaging x-ray spectrometer obtained spatially resolved measurements of Ti K-α emission. Density profiles were measured from K-α intensity. Ti ionization state distributions and electron temperatures were inferred by fitting K-α spectra to spectra from CRETIN simulations. This work shows that XRF provides a powerful tool to complement other diagnostics to make equation of state measurements of shocked materials containing a suitable tracer element.

Parallel phase-shifting self-interference digital holography with faithful reconstruction using compressive sensing

NASA Astrophysics Data System (ADS)

Wan, Yuhong; Man, Tianlong; Wu, Fan; Kim, Myung K.; Wang, Dayong

2016-11-01

We present a new self-interference digital holographic approach that allows single-shot capturing three-dimensional intensity distribution of the spatially incoherent objects. The Fresnel incoherent correlation holographic microscopy is combined with parallel phase-shifting technique to instantaneously obtain spatially multiplexed phase-shifting holograms. The compressive-sensing-based reconstruction algorithm is implemented to reconstruct the original object from the under sampled demultiplexed holograms. The scheme is verified with simulations. The validity of the proposed method is experimentally demonstrated in an indirectly way by simulating the use of specific parallel phase-shifting recording device.

Micron-scale mapping of megagauss magnetic fields using optical polarimetry to probe hot electron transport in petawatt-class laser-solid interactions.

PubMed

Chatterjee, Gourab; Singh, Prashant Kumar; Robinson, A P L; Blackman, D; Booth, N; Culfa, O; Dance, R J; Gizzi, L A; Gray, R J; Green, J S; Koester, P; Kumar, G Ravindra; Labate, L; Lad, Amit D; Lancaster, K L; Pasley, J; Woolsey, N C; Rajeev, P P

2017-08-21

The transport of hot, relativistic electrons produced by the interaction of an intense petawatt laser pulse with a solid has garnered interest due to its potential application in the development of innovative x-ray sources and ion-acceleration schemes. We report on spatially and temporally resolved measurements of megagauss magnetic fields at the rear of a 50-μm thick plastic target, irradiated by a multi-picosecond petawatt laser pulse at an incident intensity of ~10 20 W/cm 2 . The pump-probe polarimetric measurements with micron-scale spatial resolution reveal the dynamics of the magnetic fields generated by the hot electron distribution at the target rear. An annular magnetic field profile was observed ~5 ps after the interaction, indicating a relatively smooth hot electron distribution at the rear-side of the plastic target. This is contrary to previous time-integrated measurements, which infer that such targets will produce highly structured hot electron transport. We measured large-scale filamentation of the hot electron distribution at the target rear only at later time-scales of ~10 ps, resulting in a commensurate large-scale filamentation of the magnetic field profile. Three-dimensional hybrid simulations corroborate our experimental observations and demonstrate a beam-like hot electron transport at initial time-scales that may be attributed to the local resistivity profile at the target rear.

Impact of the spectral and spatial properties of natural light on indoor gas-phase chemistry: Experimental and modeling study.

PubMed

Blocquet, M; Guo, F; Mendez, M; Ward, M; Coudert, S; Batut, S; Hecquet, C; Blond, N; Fittschen, C; Schoemaecker, C

2018-05-01

The characteristics of indoor light (intensity, spectral, spatial distribution) originating from outdoors have been studied using experimental and modeling tools. They are influenced by many parameters such as building location, meteorological conditions, and the type of window. They have a direct impact on indoor air quality through a change in chemical processes by varying the photolysis rates of indoor pollutants. Transmittances of different windows have been measured and exhibit different wavelength cutoffs, thus influencing the potential of different species to be photolysed. The spectral distribution of light entering indoors through the windows was measured under different conditions and was found to be weakly dependent on the time of day for indirect cloudy, direct sunshine, partly cloudy conditions contrary to the light intensity, in agreement with calculations of the transmittance as a function of the zenithal angle and the calculated outdoor spectral distribution. The same conclusion can be drawn concerning the position within the room. The impact of these light characteristics on the indoor chemistry has been studied using the INCA-Indoor model by considering the variation in the photolysis rates of key indoor species. Depending on the conditions, photolysis processes can lead to a significant production of radicals and secondary species. © 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Observation of coherent backscattering of light in ultracold ^85Rb

NASA Astrophysics Data System (ADS)

Kulatunga, P.; Sukenik, C. I.; Havey, M. D.; Kupriyanov, D. V.; Sokolov, I. M.

2002-05-01

We report investigation of multiple coherent light scattering from ^85Rb atoms confined in a magneto-optic trap. In experimental studies, measurements are made of coherent backscattering of a low-intensity probe beam tuned near the F = 3 - F' = 4 transition in ^85Rb atoms. Polarization of backscattered light is determined by a backscattering polarimeter; the spatial distribution of light intensity is measured by a liquid-nitrogen cooled CCD camera set in the focal plane of the analyzing optics. The instrument has angular resolution of about 100 micro-radians, and a polarization analyzing power of roughly 1000. In this paper we describe the instrument details, including calibration procedures, and our measurements of atomic coherent backscattering. In a theoretical study of intensity enhancement of near-resonant backscattered light from cold ^85,87Rb atoms, we consider scattering orders up to 8 and a Gaussian atom distribution in the MOT. Enhancement factors are calculated for all D1 and D2 hyperfine components and for both isotopes.

Spatio-temporal variations in bloom of the red-tide dinoflagellate Karenia mikimotoi in Imari Bay, Japan, in 2014: Factors controlling horizontal and vertical distribution.

PubMed

Aoki, Kazuhiro; Kameda, Takahiko; Yamatogi, Toshifumi; Ishida, Naoya; Hirae, Sou; Kawaguchi, Mayumi; Syutou, Toshio

2017-11-15

A massive bloom of the dinoflagellate Karenia mikimotoi appeared in 2014 in Imari Bay, Japan. Bloom dynamics and hydrographical conditions were examined by field survey. The bloom initially developed in the eastern area of Imari Bay, subsequently after rainfall during the neap tides, cell density exceeded over 10,000cellsml. Vertical distribution of K. mikimotoi was primarily controlled by the light intensity and secondarily by the water quality during the daytime. Almost all cell-density maxima occurred in depths with weak daytime light intensities of <300μmolm -2 s -1 . In some cases of weak light intensity, cell-density maxima occurred in depths with favorable hydrodynamic conditions for the growth. Spatially classified areas were identified by cluster analysis using the growth rate calculated from seawater temperature and salinity. This study quantitatively evaluated the environmental factors of the eastern area, where the bloom initially occurred, during the development of the bloom. Copyright © 2017 Elsevier Ltd. All rights reserved.

Determination of Spatial Distribution of Air Pollution by Dye Laser Measurement of Differential Absorption of Elastic Backscatter

NASA Technical Reports Server (NTRS)

Ahmed, S. A.; Gergely, J. S.

1973-01-01

This paper presents the results of an analytical study of a lidar system which uses tunable organic dye lasers to accurately determine spatial distribution of molecular air pollutants. Also described will be experimental work to date on simultaneous multiwavelength output dye laser sources for this system. Basically the scheme determines the concentration of air pollutants by measuring the differential absorption of an (at least) two wavelength lidar signal elastically backscattered by the atmosphere. Only relative measurements of the backscattered intensity at each of the two wavelengths, one on and one off the resonance absorption of the pollutant in question, are required. The various parameters of the scheme are examined and the component elements required for a system of this type discussed, with emphasis on the dye laser source. Potential advantages of simultaneous multiwavelength outputs are described. The use of correlation spectroscopy in this context is examined. Comparisons are also made for the use of infrared probing wavelengths and sources instead of dye lasers. Estimates of the sensitivity and accuracy of a practical dye laser system of this type, made for specific pollutants, snow it to have inherent advantages over other schemes for determining pollutant spatial distribution.

Global biomass production potentials exceed expected future demand without the need for cropland expansion

PubMed Central

Mauser, Wolfram; Klepper, Gernot; Zabel, Florian; Delzeit, Ruth; Hank, Tobias; Putzenlechner, Birgitta; Calzadilla, Alvaro

2015-01-01

Global biomass demand is expected to roughly double between 2005 and 2050. Current studies suggest that agricultural intensification through optimally managed crops on today's cropland alone is insufficient to satisfy future demand. In practice though, improving crop growth management through better technology and knowledge almost inevitably goes along with (1) improving farm management with increased cropping intensity and more annual harvests where feasible and (2) an economically more efficient spatial allocation of crops which maximizes farmers' profit. By explicitly considering these two factors we show that, without expansion of cropland, today's global biomass potentials substantially exceed previous estimates and even 2050s' demands. We attribute 39% increase in estimated global production potentials to increasing cropping intensities and 30% to the spatial reallocation of crops to their profit-maximizing locations. The additional potentials would make cropland expansion redundant. Their geographic distribution points at possible hotspots for future intensification. PMID:26558436

Global biomass production potentials exceed expected future demand without the need for cropland expansion.

PubMed

Mauser, Wolfram; Klepper, Gernot; Zabel, Florian; Delzeit, Ruth; Hank, Tobias; Putzenlechner, Birgitta; Calzadilla, Alvaro

2015-11-12

Global biomass demand is expected to roughly double between 2005 and 2050. Current studies suggest that agricultural intensification through optimally managed crops on today's cropland alone is insufficient to satisfy future demand. In practice though, improving crop growth management through better technology and knowledge almost inevitably goes along with (1) improving farm management with increased cropping intensity and more annual harvests where feasible and (2) an economically more efficient spatial allocation of crops which maximizes farmers' profit. By explicitly considering these two factors we show that, without expansion of cropland, today's global biomass potentials substantially exceed previous estimates and even 2050s' demands. We attribute 39% increase in estimated global production potentials to increasing cropping intensities and 30% to the spatial reallocation of crops to their profit-maximizing locations. The additional potentials would make cropland expansion redundant. Their geographic distribution points at possible hotspots for future intensification.

Enhancement factor in low-coherence enhanced backscattering and its applications for characterizing experimental skin carcinogenesis

NASA Astrophysics Data System (ADS)

Liu, Jingjing; Xu, Zhengbin; Song, Qinghai; Konger, Raymond L.; Kim, Young L.

2010-05-01

We experimentally study potential mechanisms by which the enhancement factor in low-coherence enhanced backscattering (LEBS) can probe subtle variations in radial intensity distribution in weakly scattering media. We use enhanced backscattering of light by implementing either (1) low spatial coherence illumination or (2) multiple spatially independent detections using a microlens array under spatially coherent illumination. We show that the enhancement factor in these configurations is a measure of the integrated intensity within the localized coherence or detection area, which can exhibit strong dependence on small perturbations in scattering properties. To further evaluate the utility of the LEBS enhancement factor, we use a well-established animal model of cutaneous two-stage chemical carcinogenesis. In this pilot study, we demonstrate that the LEBS enhancement factor can be substantially altered at a stage of preneoplasia. Our animal result supports the idea that early carcinogenesis can cause subtle alterations in the scattering properties that can be captured by the LEBS enhancement factor. Thus, the LEBS enhancement factor has the potential as an easily measurable biomarker in skin carcinogenesis.

Lightning characteristics of derecho producing mesoscale convective systems

NASA Astrophysics Data System (ADS)

Bentley, Mace L.; Franks, John R.; Suranovic, Katelyn R.; Barbachem, Brent; Cannon, Declan; Cooper, Stonie R.

2016-06-01

Derechos, or widespread, convectively induced wind storms, are a common warm season phenomenon in the Central and Eastern United States. These damaging and severe weather events are known to sweep quickly across large spatial regions of more than 400 km and produce wind speeds exceeding 121 km h-1. Although extensive research concerning derechos and their parent mesoscale convective systems already exists, there have been few investigations of the spatial and temporal distribution of associated cloud-to-ground lightning with these events. This study analyzes twenty warm season (May through August) derecho events between 2003 and 2013 in an effort to discern their lightning characteristics. Data used in the study included cloud-to-ground flash data derived from the National Lightning Detection Network, WSR-88D imagery from the University Corporation for Atmospheric Research, and damaging wind report data obtained from the Storm Prediction Center. A spatial and temporal analysis was conducted by incorporating these data into a geographic information system to determine the distribution and lightning characteristics of the environments of derecho producing mesoscale convective systems. Primary foci of this research include: (1) finding the approximate size of the lightning activity region for individual and combined event(s); (2) determining the intensity of each event by examining the density and polarity of lightning flashes; (3) locating areas of highest lightning flash density; and (4) to provide a lightning spatial analysis that outlines the temporal and spatial distribution of flash activity for particularly strong derecho producing thunderstorm episodes.

Small-scale spatial variability of soil microbial community composition and functional diversity in a mixed forest

NASA Astrophysics Data System (ADS)

Wang, Qiufeng; Tian, Jing; Yu, Guirui

2014-05-01

Patterns in the spatial distribution of organisms provide important information about mechanisms that regulate the diversity and complexity of soil ecosystems. Therefore, information on spatial distribution of microbial community composition and functional diversity is urgently necessary. The spatial variability on a 26×36 m plot and vertical distribution (0-10 cm and 10-20 cm) of soil microbial community composition and functional diversity were studied in a natural broad-leaved Korean pine (Pinus koraiensis) mixed forest soil in Changbai Mountain. The phospholipid fatty acid (PLFA) pattern was used to characterize the soil microbial community composition and was compared with the community substrate utilization pattern using Biolog. Bacterial biomass dominated and showed higher variability than fungal biomass at all scales examined. The microbial biomass decreased with soil depths increased and showed less variability in lower 10-20 cm soil layer. The Shannon-Weaver index value for microbial functional diversity showed higher variability in upper 0-10 cm than lower 10-20 cm soil layer. Carbohydrates, carboxylic acids, polymers and amino acids are the main carbon sources possessing higher utilization efficiency or utilization intensity. At the same time, the four carbon source types contributed to the differentiation of soil microbial communities. This study suggests the higher diversity and complexity for this mix forest ecosystem. To determine the driving factors that affect this spatial variability of microorganism is the next step for our study.

[Ecological risk assessment of land use based on exploratory spatial data analysis (ESDA): a case study of Haitan Island, Fujian Province].

PubMed

Wu, Jian; Chen, Peng; Wen, Chao-Xiang; Fu, Shi-Feng; Chen, Qing-Hui

2014-07-01

As a novel environment management tool, ecological risk assessment has provided a new perspective for the quantitative evaluation of ecological effects of land-use change. In this study, Haitan Island in Fujian Province was taken as a case. Based on the Landsat TM obtained in 1990, SPOT5 RS images obtained in 2010, general layout planning map of Pingtan Comprehensive Experimental Zone in 2030, as well as the field investigation data, we established an ecological risk index to measure ecological endpoints. By using spatial autocorrelation and semivariance analysis of Exploratory Spatial Data Analysis (ESDA), the ecological risk of Haitan Island under different land-use situations was assessed, including the past (1990), present (2010) and future (2030), and the potential risk and its changing trend were analyzed. The results revealed that the ecological risk index showed obvious scale effect, with strong positive correlation within 3000 meters. High-high (HH) and low-low (LL) aggregations were predominant types in spatial distribution of ecological risk index. The ecological risk index showed significant isotropic characteristics, and its spatial distribution was consistent with Anselin Local Moran I (LISA) distribution during the same period. Dramatic spatial distribution change of each ecological risk area was found among 1990, 2010 and 2030, and the fluctuation trend and amplitude of different ecological risk areas were diverse. The low ecological risk area showed a rise-to-fall trend while the medium and high ecological risk areas showed a fall-to-rise trend. In the planning period, due to intensive anthropogenic disturbance, the high ecological risk area spread throughout the whole region. To reduce the ecological risk in land-use and maintain the regional ecological security, the following ecological risk control strategies could be adopted, i.e., optimizing the spatial pattern of land resources, protecting the key ecoregions and controlling the scale of construction land use.

Generation of flower high-order Poincaré sphere laser beams from a spatial light modulator

NASA Astrophysics Data System (ADS)

Lu, T. H.; Huang, T. D.; Wang, J. G.; Wang, L. W.; Alfano, R. R.

2016-12-01

We propose and experimentally demonstrate a new complex laser beam with inhomogeneous polarization distributions mapping onto high-order Poincaré spheres (HOPSs). The complex laser mode is achieved by superposition of Laguerre-Gaussian modes and manifests exotic flower-like localization on intensity and phase profiles. A simple optical system is used to generate a polarization-variant distribution on the complex laser mode by superposition of orthogonal circular polarizations with opposite topological charges. Numerical analyses of the polarization distribution are consistent with the experimental results. The novel flower HOPS beams can act as a new light source for photonic applications.

The substrate matters in the Raman spectroscopy analysis of cells

PubMed Central

Mikoliunaite, Lina; Rodriguez, Raul D.; Sheremet, Evgeniya; Kolchuzhin, Vladimir; Mehner, Jan; Ramanavicius, Arunas; Zahn, Dietrich R.T.

2015-01-01

Raman spectroscopy is a powerful analytical method that allows deposited and/or immobilized cells to be evaluated without complex sample preparation or labeling. However, a main limitation of Raman spectroscopy in cell analysis is the extremely weak Raman intensity that results in low signal to noise ratios. Therefore, it is important to seize any opportunity that increases the intensity of the Raman signal and to understand whether and how the signal enhancement changes with respect to the substrate used. Our experimental results show clear differences in the spectroscopic response from cells on different surfaces. This result is partly due to the difference in spatial distribution of electric field at the substrate/cell interface as shown by numerical simulations. We found that the substrate also changes the spatial location of maximum field enhancement around the cells. Moreover, beyond conventional flat surfaces, we introduce an efficient nanostructured silver substrate that largely enhances the Raman signal intensity from a single yeast cell. This work contributes to the field of vibrational spectroscopy analysis by providing a fresh look at the significance of the substrate for Raman investigations in cell research. PMID:26310910

The substrate matters in the Raman spectroscopy analysis of cells

NASA Astrophysics Data System (ADS)

Mikoliunaite, Lina; Rodriguez, Raul D.; Sheremet, Evgeniya; Kolchuzhin, Vladimir; Mehner, Jan; Ramanavicius, Arunas; Zahn, Dietrich R. T.

2015-08-01

Raman spectroscopy is a powerful analytical method that allows deposited and/or immobilized cells to be evaluated without complex sample preparation or labeling. However, a main limitation of Raman spectroscopy in cell analysis is the extremely weak Raman intensity that results in low signal to noise ratios. Therefore, it is important to seize any opportunity that increases the intensity of the Raman signal and to understand whether and how the signal enhancement changes with respect to the substrate used. Our experimental results show clear differences in the spectroscopic response from cells on different surfaces. This result is partly due to the difference in spatial distribution of electric field at the substrate/cell interface as shown by numerical simulations. We found that the substrate also changes the spatial location of maximum field enhancement around the cells. Moreover, beyond conventional flat surfaces, we introduce an efficient nanostructured silver substrate that largely enhances the Raman signal intensity from a single yeast cell. This work contributes to the field of vibrational spectroscopy analysis by providing a fresh look at the significance of the substrate for Raman investigations in cell research.

Mean intensity of the vortex Bessel-Gaussian beam in turbulent atmosphere

NASA Astrophysics Data System (ADS)

Lukin, Igor P.

2017-11-01

In this work the question of stability of the vortex Bessel-Gaussian optical beams formed in turbulent atmosphere is theoretically considered. The detailed analysis of features of spatial structure of distribution of mean intensity of vortex Bessel-Gaussian optical beams in turbulent atmosphere are analyzed. The quantitative criterion of possibility of formation of vortex Bessel-Gaussian optical beams in turbulent atmosphere is derived. It is shown that stability of the form of a vortex Bessel-Gaussian optical beam during propagation in turbulent atmosphere increases with increase of value of a topological charge of this optical beam.

Climate change and natural disasters: integrating science and practice to protect health.

PubMed

Sauerborn, Rainer; Ebi, Kristie

2012-12-17

Hydro-meteorological disasters are the focus of this paper. The authors examine, to which extent climate change increases their frequency and intensity. Review of IPCC-projections of climate-change related extreme weather events and related literature on health effects. Projections show that climate change is likely to increase the frequency, intensity, duration, and spatial distribution of a range of extreme weather events over coming decades. There is a need for strengthened collaboration between climate scientists, the health researchers and policy-makers as well as the disaster community to jointly develop adaptation strategies to protect human.

Functional resilience of microbial ecosystems in soil: How important is a spatial analysis?

NASA Astrophysics Data System (ADS)

König, Sara; Banitz, Thomas; Centler, Florian; Frank, Karin; Thullner, Martin

2015-04-01

Microbial life in soil is exposed to fluctuating environmental conditions influencing the performance of microbially mediated ecosystem services such as biodegradation of contaminants. However, as this environment is typically very heterogeneous, spatial aspects can be expected to play a major role for the ability to recover from a stress event. To determine key processes for functional resilience, simple scenarios with varying stress intensities were simulated within a microbial simulation model and the biodegradation rate in the recovery phase monitored. Parameters including microbial growth and dispersal rates were varied over a typical range to consider microorganisms with varying properties. Besides an aggregated temporal monitoring, the explicit observation of the spatio-temporal dynamics proved essential to understand the recovery process. For a mechanistic understanding of the model system, scenarios were also simulated with selected processes being switched-off. Results of the mechanistic and the spatial view show that the key factors for functional recovery with respect to biodegradation after a simple stress event depend on the location of the observed habitats. The limiting factors near unstressed areas are spatial processes - the mobility of the bacteria as well as substrate diffusion - the longer the distance to the unstressed region the more important becomes the process growth. Furthermore, recovery depends on the stress intensity - after a low stress event the spatial configuration has no influence on the key factors for functional resilience. To confirm these results, we repeated the stress scenarios but this time including an additional dispersal network representing a fungal network in soil. The system benefits from an increased spatial performance due to the higher mobility of the degrading microorganisms. However, this effect appears only in scenarios where the spatial distribution of the stressed area plays a role. With these simulations we show that spatial aspects play a main role for recovering after a severe stress event in a highly heterogeneous environment such as soil, and thus the relevance of the exact distribution of the stressed area. In consequence a spatial-mechanistic view is necessary for examining the functional resilience as the aggregated temporal view alone could not have led to these conclusions. Further research should explore the importance of a spatial view for quantifying the recovery of the ecosystem service also after more complex stress regimes.

Automated platform for determination of LEDs spatial radiation pattern

NASA Astrophysics Data System (ADS)

Vladescu, Marian; Vuza, Dan Tudor

2015-02-01

Nowadays technologies lead to remarkable properties of the light-emitting diodes (LEDs), making them attractive for more and more applications, such as: interior and exterior lighting, outdoor LED panels, traffic signals, automotive (tail and brake lights, backlighting in dashboard and switches), backlighting of display panels, LCD displays, symbols on switches, keyboards, graphic boards and measuring scales. Usually, LEDs are small light sources consisting of a chip placed into a package, which may bring additional optics to this encapsulated ensemble, resulting in a less or more complex spatial distribution of the light intensity, with particular radiation patterns. This paper presents an automated platform designed to allow a quick and accurate determination of the spatial radiation patterns of LEDs encapsulated in various packages. Keywords: LED, luminous

Characterization of multifocal T2*-weighted MRI hypointensities in the basal ganglia of elderly, community-dwelling subjects☆

PubMed Central

Glatz, Andreas; Valdés Hernández, Maria C.; Kiker, Alexander J.; Bastin, Mark E.; Deary, Ian J.; Wardlaw, Joanna M.

2013-01-01

Multifocal T2*-weighted (T2*w) hypointensities in the basal ganglia, which are believed to arise predominantly from mineralized small vessels and perivascular spaces, have been proposed as a biomarker for cerebral small vessel disease. This study provides baseline data on their appearance on conventional structural MRI for improving and automating current manual segmentation methods. Using a published thresholding method, multifocal T2*w hypointensities were manually segmented from whole brain T2*w volumes acquired from 98 community-dwelling subjects in their early 70s. Connected component analysis was used to derive the average T2*w hypointensity count and load per basal ganglia nucleus, as well as the morphology of their connected components, while nonlinear spatial probability mapping yielded their spatial distribution. T1-weighted (T1w), T2-weighted (T2w) and T2*w intensity distributions of basal ganglia T2*w hypointensities and their appearance on T1w and T2w MRI were investigated to gain further insights into the underlying tissue composition. In 75/98 subjects, on average, 3 T2*w hypointensities with a median total volume per intracranial volume of 50.3 ppm were located in and around the globus pallidus. Individual hypointensities appeared smooth and spherical with a median volume of 12 mm3 and median in-plane area of 4 mm2. Spatial probability maps suggested an association between T2*w hypointensities and the point of entry of lenticulostriate arterioles into the brain parenchyma. T1w and T2w and especially the T2*w intensity distributions of these hypointensities, which were negatively skewed, were generally not normally distributed indicating an underlying inhomogeneous tissue structure. Globus pallidus T2*w hypointensities tended to appear hypo- and isointense on T1w and T2w MRI, whereas those from other structures appeared iso- and hypointense. This pattern could be explained by an increased mineralization of the globus pallidus. In conclusion, the characteristic spatial distribution and appearance of multifocal basal ganglia T2*w hypointensities in our elderly cohort on structural MRI appear to support the suggested association with mineralized proximal lenticulostriate arterioles and perivascular spaces. PMID:23769704

A new macroseismic intensity prediction equation and magnitude estimates of the 1811-1812 New Madrid and 1886 Charleston, South Carolina, earthquakes

NASA Astrophysics Data System (ADS)

Boyd, O. S.; Cramer, C. H.

2013-12-01

We develop an intensity prediction equation (IPE) for the Central and Eastern United States, explore differences between modified Mercalli intensities (MMI) and community internet intensities (CII) and the propensity for reporting, and estimate the moment magnitudes of the 1811-1812 New Madrid, MO, and 1886 Charleston, SC, earthquakes. We constrain the study with North American census data, the National Oceanic and Atmospheric Administration MMI dataset (responses between 1924 and 1985), and the USGS ';Did You Feel It?' CII dataset (responses between June, 2000 and August, 2012). The combined intensity dataset has more than 500,000 felt reports for 517 earthquakes with magnitudes between 2.5 and 7.2. The IPE has the basic form, MMI=c1+c2M+c3exp(λ)+c4λ. where M is moment magnitude and λ is mean log hypocentral distance. Previous IPEs use a limited dataset of MMI, do not differentiate between MMI and CII data in the CEUS, nor account for spatial variations in population. These factors can have an impact at all magnitudes, especially the last factor at large magnitudes and small intensities where the population drops to zero in the Atlantic Ocean and Gulf of Mexico. We assume that the number of reports of a given intensity have hypocentral distances that are log-normally distributed, the distribution of which is modulated by population and the propensity for individuals to report their experience. We do not account for variations in stress drop, regional variations in Q, or distance-dependent geometrical spreading. We simulate the distribution of reports of a given intensity accounting for population and use a grid search method to solve for the fraction of population to report the intensity, the standard deviation of the log-normal distribution and the mean log hypocentral distance, which appears in the above equation. We find that lower intensities, both CII and MMI, are less likely to be reported than greater intensities. Further, there are strong spatial variations in the level of CII reporting. For example, large metropolitan areas appear to have a lower level of reporting relative to rural areas. In general, we find that intensities decrease with increasing distance and decreasing magnitude, as expected. Coefficients for the IPE are c1=1.98×0.13 c2=1.76×0.02 c3=-0.0027×0.0004, and c4=-1.26×0.03. We find significant differences in mean log hypocentral distance between MMI- and CII-based reporting, particularly at smaller mean log distance and higher intensity. Values of mean log distance for CII at high intensity tend to be smaller than for MMI at the same value of intensity. The new IPE leads to magnitude estimates for the 1811-1812 New Madrid earthquakes that are within the broad range of those determined previously. Using three MMI datasets for the New Madrid mainshocks, the new relation results in estimates for the moment magnitudes of the December 16th, 1811, January 23rd, 1812, and February 7th, 1812 mainshocks and December 16th dawn aftershock of 7.1¬¬-7.4, 7.2, 7.5-7.7, and 6.7-7.2, respectively, with a magnitude uncertainty of about ×0.4 units. We estimate a magnitude of 7.0×0.3 for the 1886 Charleston, SC earthquake.

Beam shaping with vortex beam generated by liquid crystal spatial light modulator

NASA Astrophysics Data System (ADS)

Gao, Yue; Liu, Ke; Sun, Zeng-yu; Guo, Lei; Gan, Yu

2015-02-01

An optical vortex is a beam of light with phase varying in a corkscrew-like manner along its direction of propagation and so has a helical wavefront. When such a vectorial vortex beam and the Gaussian beam with orthogonal polarization are focused by low NA lens, the Gaussian component causes a focal intensity distribution with a solid center and the vortex component causes a donut distribution with hollow dark center. The shape of the focus can be continuously varied by continuously adjusting the relative weight of the two components. Flat top focusing can be obtained under appropriate conditions. It is demonstrated through experiments with a liquid crystal spatial light modulator in such a beam, that flattop focus can be obtained by vectorial vortex beams with topological charge of +1 to achieve beam shaping vortex.

SU-E-I-44: Some Preliminary Analysis of Angular Distribution of X-Ray Scattered On Soft Tissues

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ganezer, K; Krmar, M; Cvejic, Z

2015-06-15

Purpose: The angular distribution of x-radiation scattered at small angles (up to 16 degrees) from several different animal soft tissue (skin, fat, muscle, retina, etc) were measured using standard equipment devoted to study of crystal structure which provides excellent geometry conditions of measurements. showed measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Methods: An x-ray scattering profilemore » usually consists of sharp diffraction peak; however some properties of the spatial profiles of scattered radiation as intensity, the peak position, height, area, FWHM, the ratio of peak heights, etc. Results: The data contained measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Measurements of different samples in the very preliminary phase showed that simple biological material used in study showed slightly different scattering pattern, especially at higher angles (around 10degrees). Intensity of radiation scattered from same tissue type is very dependent on water content and several more parameters. Conclusion: This preliminary study using animal soft tissues on the angular distributions of scattered x-rays suggests that angular distributions of X-rays scattered off of soft tissues might be useful in distinguishing healthy tissue from malignant soft tissue.« less

A semi-analytical study of positive corona discharge in wire-plane electrode configuration

NASA Astrophysics Data System (ADS)

Yanallah, K.; Pontiga, F.; Chen, J. H.

2013-08-01

Wire-to-plane positive corona discharge in air has been studied using an analytical model of two species (electrons and positive ions). The spatial distributions of electric field and charged species are obtained by integrating Gauss's law and the continuity equations of species along the Laplacian field lines. The experimental values of corona current intensity and applied voltage, together with Warburg's law, have been used to formulate the boundary condition for the electron density on the corona wire. To test the accuracy of the model, the approximate electric field distribution has been compared with the exact numerical solution obtained from a finite element analysis. A parametrical study of wire-to-plane corona discharge has then been undertaken using the approximate semi-analytical solutions. Thus, the spatial distributions of electric field and charged particles have been computed for different values of the gas pressure, wire radius and electrode separation. Also, the two dimensional distribution of ozone density has been obtained using a simplified plasma chemistry model. The approximate semi-analytical solutions can be evaluated in a negligible computational time, yet provide precise estimates of corona discharge variables.

Quantitative imaging of single-shot liquid distributions in sprays using broadband flash x-ray radiography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halls, B. R.; Roy, S.; Gord, J. R.

Flash x-ray radiography is used to capture quantitative, two-dimensional line-of-sight averaged, single-shot liquid distribution measurements in impinging jet sprays. The accuracy of utilizing broadband x-ray radiation from compact flash tube sources is investigated for a range of conditions by comparing the data with radiographic high-speed measurements from a narrowband, high-intensity synchrotron x-ray facility at the Advanced Photon Source (APS) of Argonne National Laboratory. The path length of the liquid jets is varied to evaluate the effects of energy dependent x-ray attenuation, also known as spectral beam hardening. The spatial liquid distributions from flash x-ray and synchrotron-based radiography are compared, alongmore » with spectral characteristics using Taylor’s hypothesis. The results indicate that quantitative, single-shot imaging of liquid distributions can be achieved using broadband x-ray sources with nanosecond temporal resolution. Practical considerations for optimizing the imaging system performance are discussed, including the coupled effects of x-ray bandwidth, contrast, sensitivity, spatial resolution, temporal resolution, and spectral beam hardening.« less

Accounting for heterogeneity of nutrient dynamics in riverscapes through spatially distributed models

NASA Astrophysics Data System (ADS)

Wollheim, W. M.; Stewart, R. J.

2011-12-01

Numerous types of heterogeneity exist within river systems, leading to hotspots of nutrient sources, sinks, and impacts embedded within an underlying gradient defined by river size. This heterogeneity influences the downstream propagation of anthropogenic impacts across flow conditions. We applied a river network model to explore how nitrogen saturation at river network scales is influenced by the abundance and distribution of potential nutrient processing hotspots (lakes, beaver ponds, tributary junctions, hyporheic zones) under different flow conditions. We determined that under low flow conditions, whole network nutrient removal is relatively insensitive to the number of hotspots because the underlying river network structure has sufficient nutrient processing capacity. However, hotspots become more important at higher flows and greatly influence the spatial distribution of removal within the network at all flows, suggesting that identification of heterogeneity is critical to develop predictive understanding of nutrient removal processes under changing loading and climate conditions. New temporally intensive data from in situ sensors can potentially help to better understand and constrain these dynamics.

Determinants of the geographical distribution of endemic giardiasis in Ontario, Canada: a spatial modelling approach.

PubMed

Odoi, A; Martin, S W; Michel, P; Holt, J; Middleton, D; Wilson, J

2004-10-01

Giardiasis surveillance data as well as drinking water, socioeconomic and land-use data were used in spatial regression models to investigate determinants of the geographic distribution of endemic giardiasis in southern Ontario. Higher giardiasis rates were observed in areas using surface water [rate ratio (RR) 2.36, 95 % CI 1.38-4.05] and in rural areas (RR 1.79, 95 % CI 1.32-2.37). Lower rates were observed in areas using filtered water (RR 0.55, 95 % CI 0.42-0.94) and in those with high median income (RR 0.62, 95 % CI 0.42-0.92). Chlorination of drinking water, cattle density and intensity of manure application on farmland were not significant determinants. The study shows that waterborne transmission plays an important role in giardiasis distribution in southern Ontario and that well-collected routine surveillance data could be useful for investigation of disease determinants and identification of high-risk communities. This information is useful in guiding decisions on control strategies.

A probabilistic tornado wind hazard model for the continental United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hossain, Q; Kimball, J; Mensing, R

A probabilistic tornado wind hazard model for the continental United States (CONUS) is described. The model incorporates both aleatory (random) and epistemic uncertainties associated with quantifying the tornado wind hazard parameters. The temporal occurrences of tornadoes within the continental United States (CONUS) is assumed to be a Poisson process. A spatial distribution of tornado touchdown locations is developed empirically based on the observed historical events within the CONUS. The hazard model is an aerial probability model that takes into consideration the size and orientation of the facility, the length and width of the tornado damage area (idealized as a rectanglemore » and dependent on the tornado intensity scale), wind speed variation within the damage area, tornado intensity classification errors (i.e.,errors in assigning a Fujita intensity scale based on surveyed damage), and the tornado path direction. Epistemic uncertainties in describing the distributions of the aleatory variables are accounted for by using more than one distribution model to describe aleatory variations. The epistemic uncertainties are based on inputs from a panel of experts. A computer program, TORNADO, has been developed incorporating this model; features of this program are also presented.« less

Microparticles controllable accumulation, arrangement, and spatial shaping performed by tapered-fiber-based laser-induced convection flow.

PubMed

Zhang, Yu; Lei, Jiaojie; Zhang, Yaxun; Liu, Zhihai; Zhang, Jianzhong; Yang, Xinghua; Yang, Jun; Yuan, Libo

2017-10-30

The ability to arrange cells and/or microparticles into the desired pattern is critical in biological, chemical, and metamaterial studies and other applications. Researchers have developed a variety of patterning techniques, which either have a limited capacity to simultaneously trap massive particles or lack the spatial resolution necessary to manipulate individual particle. Several approaches have been proposed that combine both high spatial selectivity and high throughput simultaneously. However, those methods are complex and difficult to fabricate. In this article, we propose and demonstrate a simple method that combines the laser-induced convection flow and fiber-based optical trapping methods to perform both regular and special spatial shaping arrangement. Essentially, we combine a light field with a large optical intensity gradient distribution and a thermal field with a large temperature gradient distribution to perform the microparticles shaping arrangement. The tapered-fiber-based laser-induced convection flow provides not only the batch manipulation of massive particles, but also the finer manipulation of special one or several particles, which break out the limit of single-fiber-based massive/individual particles photothermal manipulation. The combination technique allows for microparticles quick accumulation, single-layer and multilayer arrangement; special spatial shaping arrangement/adjustment, and microparticles sorting.

Impact of East Asian Summer Monsoon on Surface Ozone Pattern in China

NASA Astrophysics Data System (ADS)

Li, Shu; Wang, Tijian; Huang, Xing; Pu, Xi; Li, Mengmeng; Chen, Pulong; Yang, Xiu-Qun; Wang, Minghuai

2018-01-01

Tropospheric ozone plays a key role in regional and global atmospheric and climate systems. In East Asia, ozone can be affected both in concentration level and spatial pattern by typical monsoon climate. This paper uses three different indices to identify the strength of East Asian summer monsoon (EASM) and explores the possible impact of EASM intensity on the ozone pattern through synthetic and process analysis. The difference in ozone between three strong and three weak monsoon years was analyzed using the simulations from regional climate model RegCM4-Chem. It was found that EASM intensity can significantly influence the spatial distribution of ozone in the lower troposphere. When EASM is strong, ozone in the eastern part of China (28°N - 42° N) is reduced, but the inverse is detected in the north and south. The surface ozone difference ranges from -7 to 7 ppbv during the 3 months (June to August) of the EASM, with the most obvious difference in August. Difference of the 3 months' average ozone ranges from -3.5 to 4 ppbv. Process analysis shows that the uppermost factor controlling ozone level during summer monsoon seasons is the chemistry process. Interannual variability of EASM can impact the spatial distribution of ozone through wind in the lower troposphere, cloud cover, and downward shortwave radiation, which affect the transport and chemical formation of ozone. The phenomenon should be addressed when considering the interaction between ozone and the climate in East Asia region.

Geographic variations of ecosystem service intensity in Fuzhou City, China.

PubMed

Hu, Xisheng; Hong, Wei; Qiu, Rongzu; Hong, Tao; Chen, Can; Wu, Chengzhen

2015-04-15

Ecosystem services are strongly influenced by the landscape configuration of natural and human systems. So they are heterogeneous across landscapes. However lack of the knowledge of spatial variations of ecosystem services constrains the effective management and conservation of ecosystems. We presented a spatially explicit and quantitative assessment of the geographic variations in ecosystem services for the Fuzhou City in 2009 using exploratory spatial data analysis (ESDA) and semivariance analysis. Results confirmed a significant and positive spatial autocorrelation, and revealed several hot-spots and cold-spots for the spatial distribution of ecosystem service intensity (ESI) in the study area. Also the trend surface analysis indicated that the level of ESI tended to be reduced gradually from north to south and from west to east, with a trough in the urban central area, which was quite in accordance with land-use structure. A more precise cluster map was then developed using the range of lag distance, deriving from semivariance analysis, as neighborhood size instead of default value in the software of ESRI ArcGIS 10.0, and geographical clusters where population growth and land-use pressure varied significantly and positively with ESI across the city were also created by geographically weighted regression (GWR). This study has good policy implications applicable to prioritize areas for conservation or construction, and design ecological corridor to improve ecosystem service delivery to benefiting areas. Copyright © 2015 Elsevier B.V. All rights reserved.

Development and Characterization of a Laser-Induced Acoustic Desorption Source.

PubMed

Huang, Zhipeng; Ossenbrüggen, Tim; Rubinsky, Igor; Schust, Matthias; Horke, Daniel A; Küpper, Jochen

2018-03-20

A laser-induced acoustic desorption source, developed for use at central facilities, such as free-electron lasers, is presented. It features prolonged measurement times and a fixed interaction point. A novel sample deposition method using aerosol spraying provides a uniform sample coverage and hence stable signal intensity. Utilizing strong-field ionization as a universal detection scheme, the produced molecular plume is characterized in terms of number density, spatial extend, fragmentation, temporal distribution, translational velocity, and translational temperature. The effect of desorption laser intensity on these plume properties is evaluated. While translational velocity is invariant for different desorption laser intensities, pointing to a nonthermal desorption mechanism, the translational temperature increases significantly and higher fragmentation is observed with increased desorption laser fluence.

Novel Image Processing Interface to Relate DSB Spatial Distribution from Immunofluorescence Foci Experiments to the State-of-the-Art Models of DNA Breakage

NASA Technical Reports Server (NTRS)

Ponomarev, A. L.; Cucinotta, F. A.

2004-01-01

A recently developed software (NASARadiationTrackImage) allows a quick and automatic segmentation of foci that indicate spatial localization of specific proteins that are visualized by immunofluorescence. Of interest are the spatial and temporal distribution of foci such as gammaH2AX, a signal of the phosphorylation of a variant of the histone H2A that has been shown to correspond to DSBs, or proteins involved in DSB processing, such as ATM, Rad51, and p53, following exposures of human cells to high charge and energy (HZE) ion irradiation. Experimental data are recorded as sets of two-dimensional images in color with cells and foci of gammaH2AX, ATM, Rad51 or others shown. Different cells, levels of radiation and timing after radiation were recorded. The software allows us to calculate the number of foci per cell, overall intensity of light in foci and their spatial organization. A simple statistical model allows for testing of foci overlap (eclipse). A more complex statistical model previously known as DNAbreak simulates track structure and random chromosome geometry. It has one adjustable parameter corresponding to an average intensity of DSB creation in cubic micrometers of DNA volume per particle track or unit dose. Its limitation is the low-resolution limit both in physical space and DSB's along DNA. It works adequately on the scale of a cell and provides further insights on how the geometry of tracks and DNA affects genomic damage of the cell and subsequent repair. Future developments of the model for the description of the time evolution of DNA damage response proteins, and more robust track structure models will be discussed.

A General-purpose Framework for Parallel Processing of Large-scale LiDAR Data

NASA Astrophysics Data System (ADS)

Li, Z.; Hodgson, M.; Li, W.

2016-12-01

Light detection and ranging (LiDAR) technologies have proven efficiency to quickly obtain very detailed Earth surface data for a large spatial extent. Such data is important for scientific discoveries such as Earth and ecological sciences and natural disasters and environmental applications. However, handling LiDAR data poses grand geoprocessing challenges due to data intensity and computational intensity. Previous studies received notable success on parallel processing of LiDAR data to these challenges. However, these studies either relied on high performance computers and specialized hardware (GPUs) or focused mostly on finding customized solutions for some specific algorithms. We developed a general-purpose scalable framework coupled with sophisticated data decomposition and parallelization strategy to efficiently handle big LiDAR data. Specifically, 1) a tile-based spatial index is proposed to manage big LiDAR data in the scalable and fault-tolerable Hadoop distributed file system, 2) two spatial decomposition techniques are developed to enable efficient parallelization of different types of LiDAR processing tasks, and 3) by coupling existing LiDAR processing tools with Hadoop, this framework is able to conduct a variety of LiDAR data processing tasks in parallel in a highly scalable distributed computing environment. The performance and scalability of the framework is evaluated with a series of experiments conducted on a real LiDAR dataset using a proof-of-concept prototype system. The results show that the proposed framework 1) is able to handle massive LiDAR data more efficiently than standalone tools; and 2) provides almost linear scalability in terms of either increased workload (data volume) or increased computing nodes with both spatial decomposition strategies. We believe that the proposed framework provides valuable references on developing a collaborative cyberinfrastructure for processing big earth science data in a highly scalable environment.

Projecting future impacts of hurricanes on the carbon balance of eastern U.S. forests

NASA Astrophysics Data System (ADS)

Fisk, J. P.; Hurtt, G. C.; Chambers, J. Q.; Zeng, H.; Dolan, K.; Flanagan, S.; Rourke, O.; Negron Juarez, R. I.

2011-12-01

In U.S. Atlantic coastal areas, hurricanes are a principal agent of catastrophic wind damage, with dramatic impacts on the structure and functioning of forests. Substantial recent progress has been made to estimate the biomass loss and resulting carbon emissions caused by hurricanes impacting the U.S. Additionally, efforts to evaluate the net effects of hurricanes on the regional carbon balance have demonstrated the importance of viewing large disturbance events in the broader context of recovery from a mosaic of past events. Viewed over sufficiently long time scales and large spatial scales, regrowth from previous storms may largely offset new emissions; however, changes in number, strength or spatial distribution of extreme disturbance events will result in changes to the equilibrium state of the ecosystem and have the potential to result in a lasting carbon source or sink. Many recent studies have linked climate change to changes in the frequency and intensity of hurricanes. In this study, we use a mechanistic ecosystem model, the Ecosystem Demography (ED) model, driven by scenarios of future hurricane activity based on historic activity and future climate projections, to evaluate how changes in hurricane frequency, intensity and spatial distribution could affect regional carbon storage and flux over the coming century. We find a non-linear response where increased storm activity reduces standing biomass stocks reducing the impacts of future events. This effect is highly dependent on the spatial pattern and repeat interval of future hurricane activity. Developing this kind of predictive modeling capability that tracks disturbance events and recovery is key to our understanding and ability to predict the carbon balance of forests.

Kinetic energy distribution of multiply charged ions in Coulomb explosion of Xe clusters.

PubMed

Heidenreich, Andreas; Jortner, Joshua

2011-02-21

We report on the calculations of kinetic energy distribution (KED) functions of multiply charged, high-energy ions in Coulomb explosion (CE) of an assembly of elemental Xe(n) clusters (average size (n) = 200-2171) driven by ultra-intense, near-infrared, Gaussian laser fields (peak intensities 10(15) - 4 × 10(16) W cm(-2), pulse lengths 65-230 fs). In this cluster size and pulse parameter domain, outer ionization is incomplete∕vertical, incomplete∕nonvertical, or complete∕nonvertical, with CE occurring in the presence of nanoplasma electrons. The KEDs were obtained from double averaging of single-trajectory molecular dynamics simulation ion kinetic energies. The KEDs were doubly averaged over a log-normal cluster size distribution and over the laser intensity distribution of a spatial Gaussian beam, which constitutes either a two-dimensional (2D) or a three-dimensional (3D) profile, with the 3D profile (when the cluster beam radius is larger than the Rayleigh length) usually being experimentally realized. The general features of the doubly averaged KEDs manifest the smearing out of the structure corresponding to the distribution of ion charges, a marked increase of the KEDs at very low energies due to the contribution from the persistent nanoplasma, a distortion of the KEDs and of the average energies toward lower energy values, and the appearance of long low-intensity high-energy tails caused by the admixture of contributions from large clusters by size averaging. The doubly averaged simulation results account reasonably well (within 30%) for the experimental data for the cluster-size dependence of the CE energetics and for its dependence on the laser pulse parameters, as well as for the anisotropy in the angular distribution of the energies of the Xe(q+) ions. Possible applications of this computational study include a control of the ion kinetic energies by the choice of the laser intensity profile (2D∕3D) in the laser-cluster interaction volume.

Assessing the relationship between groundwater nitrate and animal feeding operations in Iowa (USA)

USGS Publications Warehouse

Zirkle, Keith W.; Nolan, Bernard T.; Jones, Rena R.; Weyer, Peter J.; Ward, Mary H.; Wheeler, David C.

2016-01-01

Nitrate-nitrogen is a common contaminant of drinking water in many agricultural areas of the United States of America (USA). Ingested nitrate from contaminated drinking water has been linked to an increased risk of several cancers, specific birth defects, and other diseases. In this research, we assessed the relationship between animal feeding operations (AFOs) and groundwater nitrate in private wells in Iowa. We characterized AFOs by swine and total animal units and type (open, confined, or mixed), and we evaluated the number and spatial intensities of AFOs in proximity to private wells. The types of AFO indicate the extent to which a facility is enclosed by a roof. Using linear regression models, we found significant positive associations between the total number of AFOs within 2 km of a well (p trend < 0.001), number of open AFOs within 5 km of a well (p trend < 0.001), and number of mixed AFOs within 30 km of a well (p trend < 0.001) and the log nitrate concentration. Additionally, we found significant increases in log nitrate in the top quartiles for AFO spatial intensity, open AFO spatial intensity, and mixed AFO spatial intensity compared to the bottom quartile (0.171 log(mg/L), 0.319 log(mg/L), and 0.541 log(mg/L), respectively; all p < 0.001). We also explored the spatial distribution of nitrate-nitrogen in drinking wells and found significant spatial clustering of high-nitrate wells (> 5 mg/L) compared with low-nitrate (≤ 5 mg/L) wells (p = 0.001). A generalized additive model for high-nitrate status identified statistically significant areas of risk for high levels of nitrate. Adjustment for some AFO predictor variables explained a portion of the elevated nitrate risk. These results support a relationship between animal feeding operations and groundwater nitrate concentrations and differences in nitrate loss from confined AFOs vs. open or mixed types.

Three dimensional characterization of GaN-based light emitting diode grown on patterned sapphire substrate by confocal Raman and photoluminescence spectromicroscopy.

PubMed

Li, Heng; Cheng, Hui-Yu; Chen, Wei-Liang; Huang, Yi-Hsin; Li, Chi-Kang; Chang, Chiao-Yun; Wu, Yuh-Renn; Lu, Tien-Chang; Chang, Yu-Ming

2017-03-30

We performed depth-resolved PL and Raman spectral mappings of a GaN-based LED structure grown on a patterned sapphire substrate (PSS). Our results showed that the Raman mapping in the PSS-GaN heterointerface and the PL mapping in the In x Ga 1-x N/GaN MQWs active layer are spatially correlated. Based on the 3D construction of E 2 (high) Raman peak intensity and frequency shift, V-shaped pits in the MQWs can be traced down to the dislocations originated in the cone tip area of PSS. Detail analysis of the PL peak distribution further revealed that the indium composition in the MQWs is related to the residual strain propagating from the PSS-GaN heterointerface toward the LED surface. Numerical simulation based on the indium composition distribution also led to a radiative recombination rate distribution that shows agreement with the experimental PL intensity distribution in the In x Ga 1-x N/GaN MQWs active layer.

Three dimensional characterization of GaN-based light emitting diode grown on patterned sapphire substrate by confocal Raman and photoluminescence spectromicroscopy

PubMed Central

Li, Heng; Cheng, Hui-Yu; Chen, Wei-Liang; Huang, Yi-Hsin; Li, Chi-Kang; Chang, Chiao-Yun; Wu, Yuh-Renn; Lu, Tien-Chang; Chang, Yu-Ming

2017-01-01

We performed depth-resolved PL and Raman spectral mappings of a GaN-based LED structure grown on a patterned sapphire substrate (PSS). Our results showed that the Raman mapping in the PSS-GaN heterointerface and the PL mapping in the InxGa1−xN/GaN MQWs active layer are spatially correlated. Based on the 3D construction of E2(high) Raman peak intensity and frequency shift, V-shaped pits in the MQWs can be traced down to the dislocations originated in the cone tip area of PSS. Detail analysis of the PL peak distribution further revealed that the indium composition in the MQWs is related to the residual strain propagating from the PSS-GaN heterointerface toward the LED surface. Numerical simulation based on the indium composition distribution also led to a radiative recombination rate distribution that shows agreement with the experimental PL intensity distribution in the InxGa1−xN/GaN MQWs active layer. PMID:28358119

GSHR-Tree: a spatial index tree based on dynamic spatial slot and hash table in grid environments

NASA Astrophysics Data System (ADS)

Chen, Zhanlong; Wu, Xin-cai; Wu, Liang

2008-12-01

Computation Grids enable the coordinated sharing of large-scale distributed heterogeneous computing resources that can be used to solve computationally intensive problems in science, engineering, and commerce. Grid spatial applications are made possible by high-speed networks and a new generation of Grid middleware that resides between networks and traditional GIS applications. The integration of the multi-sources and heterogeneous spatial information and the management of the distributed spatial resources and the sharing and cooperative of the spatial data and Grid services are the key problems to resolve in the development of the Grid GIS. The performance of the spatial index mechanism is the key technology of the Grid GIS and spatial database affects the holistic performance of the GIS in Grid Environments. In order to improve the efficiency of parallel processing of a spatial mass data under the distributed parallel computing grid environment, this paper presents a new grid slot hash parallel spatial index GSHR-Tree structure established in the parallel spatial indexing mechanism. Based on the hash table and dynamic spatial slot, this paper has improved the structure of the classical parallel R tree index. The GSHR-Tree index makes full use of the good qualities of R-Tree and hash data structure. This paper has constructed a new parallel spatial index that can meet the needs of parallel grid computing about the magnanimous spatial data in the distributed network. This arithmetic splits space in to multi-slots by multiplying and reverting and maps these slots to sites in distributed and parallel system. Each sites constructs the spatial objects in its spatial slot into an R tree. On the basis of this tree structure, the index data was distributed among multiple nodes in the grid networks by using large node R-tree method. The unbalance during process can be quickly adjusted by means of a dynamical adjusting algorithm. This tree structure has considered the distributed operation, reduplication operation transfer operation of spatial index in the grid environment. The design of GSHR-Tree has ensured the performance of the load balance in the parallel computation. This tree structure is fit for the parallel process of the spatial information in the distributed network environments. Instead of spatial object's recursive comparison where original R tree has been used, the algorithm builds the spatial index by applying binary code operation in which computer runs more efficiently, and extended dynamic hash code for bit comparison. In GSHR-Tree, a new server is assigned to the network whenever a split of a full node is required. We describe a more flexible allocation protocol which copes with a temporary shortage of storage resources. It uses a distributed balanced binary spatial tree that scales with insertions to potentially any number of storage servers through splits of the overloaded ones. The application manipulates the GSHR-Tree structure from a node in the grid environment. The node addresses the tree through its image that the splits can make outdated. This may generate addressing errors, solved by the forwarding among the servers. In this paper, a spatial index data distribution algorithm that limits the number of servers has been proposed. We improve the storage utilization at the cost of additional messages. The structure of GSHR-Tree is believed that the scheme of this grid spatial index should fit the needs of new applications using endlessly larger sets of spatial data. Our proposal constitutes a flexible storage allocation method for a distributed spatial index. The insertion policy can be tuned dynamically to cope with periods of storage shortage. In such cases storage balancing should be favored for better space utilization, at the price of extra message exchanges between servers. This structure makes a compromise in the updating of the duplicated index and the transformation of the spatial index data. Meeting the needs of the grid computing, GSHRTree has a flexible structure in order to satisfy new needs in the future. The GSHR-Tree provides the R-tree capabilities for large spatial datasets stored over interconnected servers. The analysis, including the experiments, confirmed the efficiency of our design choices. The scheme should fit the needs of new applications of spatial data, using endlessly larger datasets. Using the system response time of the parallel processing of spatial scope query algorithm as the performance evaluation factor, According to the result of the simulated the experiments, GSHR-Tree is performed to prove the reasonable design and the high performance of the indexing structure that the paper presented.

The Response of Farmland Bird Communities to Agricultural Intensity as Influenced by Its Spatial Aggregation

PubMed Central

Teillard, Félix; Jiguet, Frédéric; Tichit, Muriel

2015-01-01

The shape of the relationship between biodiversity and agricultural intensity determines the range of intensities that should be targeted by conservation policies to obtain the greatest environmental benefits. Although preliminary evidence of this relationship exists, the influence of the spatial arrangement of intensity on biodiversity remains untested. We conducted a nationwide study linking agricultural intensity and its spatial arrangement to a farmland bird community of 22 species. Intensity was described with a continuous indicator based on Input Cost per hectare, which was relevant for both livestock and crop production. We used the French Breeding Bird Survey to compute several descriptors of the farmland bird community along the intensity gradient and tested for the significance of an interaction effect between intensity and its spatial aggregation on these descriptors. We found that the bird community was comprised of both winner and loser species with regard to intensity. The community composition descriptors (trophic level, specialisation, and specialisation for grassland indices) displayed non-linear relationships to intensity, with steeper slopes in the lower intensity range. We found a significant interaction effect between intensity and its spatial aggregation on the grassland specialisation index of the bird community; the effect of agricultural intensity was strengthened by its spatial aggregation. We suggest that an opportunity to improve the effectiveness of conservation policies exists by targeting measures in areas where intensity is moderate to low and aggregated. The effect of the aggregation of agricultural intensity on biodiversity should be considered in other scales and taxa when developing optimal policy targeting and intensity allocation strategies. PMID:25799552

Inverse analysis of non-uniform temperature distributions using multispectral pyrometry

NASA Astrophysics Data System (ADS)

Fu, Tairan; Duan, Minghao; Tian, Jibin; Shi, Congling

2016-05-01

Optical diagnostics can be used to obtain sub-pixel temperature information in remote sensing. A multispectral pyrometry method was developed using multiple spectral radiation intensities to deduce the temperature area distribution in the measurement region. The method transforms a spot multispectral pyrometer with a fixed field of view into a pyrometer with enhanced spatial resolution that can give sub-pixel temperature information from a "one pixel" measurement region. A temperature area fraction function was defined to represent the spatial temperature distribution in the measurement region. The method is illustrated by simulations of a multispectral pyrometer with a spectral range of 8.0-13.0 μm measuring a non-isothermal region with a temperature range of 500-800 K in the spot pyrometer field of view. The inverse algorithm for the sub-pixel temperature distribution (temperature area fractions) in the "one pixel" verifies this multispectral pyrometry method. The results show that an improved Levenberg-Marquardt algorithm is effective for this ill-posed inverse problem with relative errors in the temperature area fractions of (-3%, 3%) for most of the temperatures. The analysis provides a valuable reference for the use of spot multispectral pyrometers for sub-pixel temperature distributions in remote sensing measurements.

Using kernel density estimation to understand the influence of neighbourhood destinations on BMI

PubMed Central

King, Tania L; Bentley, Rebecca J; Thornton, Lukar E; Kavanagh, Anne M

2016-01-01

Objectives Little is known about how the distribution of destinations in the local neighbourhood is related to body mass index (BMI). Kernel density estimation (KDE) is a spatial analysis technique that accounts for the location of features relative to each other. Using KDE, this study investigated whether individuals living near destinations (shops and service facilities) that are more intensely distributed rather than dispersed, have lower BMIs. Study design and setting A cross-sectional study of 2349 residents of 50 urban areas in metropolitan Melbourne, Australia. Methods Destinations were geocoded, and kernel density estimates of destination intensity were created using kernels of 400, 800 and 1200 m. Using multilevel linear regression, the association between destination intensity (classified in quintiles Q1(least)–Q5(most)) and BMI was estimated in models that adjusted for the following confounders: age, sex, country of birth, education, dominant household occupation, household type, disability/injury and area disadvantage. Separate models included a physical activity variable. Results For kernels of 800 and 1200 m, there was an inverse relationship between BMI and more intensely distributed destinations (compared to areas with least destination intensity). Effects were significant at 1200 m: Q4, β −0.86, 95% CI −1.58 to −0.13, p=0.022; Q5, β −1.03 95% CI −1.65 to −0.41, p=0.001. Inclusion of physical activity in the models attenuated effects, although effects remained marginally significant for Q5 at 1200 m: β −0.77 95% CI −1.52, −0.02, p=0.045. Conclusions This study conducted within urban Melbourne, Australia, found that participants living in areas of greater destination intensity within 1200 m of home had lower BMIs. Effects were partly explained by physical activity. The results suggest that increasing the intensity of destination distribution could reduce BMI levels by encouraging higher levels of physical activity. PMID:26883235

Technical characterization of an ultrasound source for noninvasive thermoablation by high-intensity focused ultrasound.

PubMed

Köhrmann, K U; Michel, M S; Steidler, A; Marlinghaus, E; Kraut, O; Alken, P

2002-08-01

To develop a generator for high-intensity focused ultrasound (HIFU, a method of delivering ultrasonic energy with resultant heat and tissue destruction to a tight focus at a selected depth within the body), designed for extracorporeal coupling to allow various parenchymal organs to be treated. The ultrasound generated by a cylindrical piezo-ceramic element is focused at a depth of 10 cm using a parabolic reflector with a diameter of 10 cm. A diagnostic B-mode ultrasonographic transducer is integrated into the source to allow the focus to be located in the target area. The field distribution of the sound pressure was measured in degassed water using a needle hydrophone. An ultrasound-force balance was used to determine the acoustic power. These measurements allowed the spatially averaged sound intensity to be calculated. The morphology and extent of tissue necrosis induced by HIFU was examined on an ex-vivo kidney model. The two-dimensional field distribution resulted in an approximately ellipsoidal focus of 32 x 4 mm (- 6 dB). The spatially maximum averaged sound intensity was 8591 W/cm2 at an electrical power of 400 W. The lesion caused to the ex-vivo kidney at this maximum generator power with a pulse duration of 2 s was a clearly delineated ellipsoidal coagulation necrosis up to 8.8 x 2.3 mm (length x width) and with central liquefied necrosis of 7.9 x 1.9 mm. This newly developed ultrasound generator with a focal length of 10 cm can induce clear necrosis in parenchymal tissue. Because of its specific configuration and the available power range of the ultrasound generator, there is potential for therapeutic noninvasive ablation of tissue deep within a patient's body.

Radial and azimuthal distribution of Io's oxygen neutral cloud observed by Hisaki/EXCEED

NASA Astrophysics Data System (ADS)

Koga, R.; Tsuchiya, F.; Kagitani, M.; Sakanoi, T.; Yoneda, M.; Yoshikawa, I.; Yoshioka, K.; Murakami, G.; Yamazaki, A.; Kimura, T.; Smith, H. T.

2017-12-01

We report the spatial distributions of oxygen neural cloud surrounding Jupiter's moon Io and along Io's orbit observed by the HISAKI satellite. Atomic oxygen and sulfur in Io's atmosphere escape from the exobase and move to corona (< 5.8 Io radii, the boundary where Jupiter's gravity begins to dominate) and neutral clouds (> 5.8 Io radii) mainly due to atmospheric sputtering. Io plasma torus is formed by ionization of these atoms by electron impact and charge exchange processes. It is essential to examine the dominant source of Io plasma torus, particularly in the vicinity of Io (<5.8 Io radii; atmosphere and corona) or the region away from Io (>5.8 Io radii; extended neutral clouds). The spatial distribution of oxygen and sulfur neutral clouds is important to understand the source. The extreme ultraviolet spectrometer called EXCEED (Extreme Ultraviolet Spectroscope for Exospheric Dynamics) installed on the Hisaki satellite observed Io plasma torus continuously in 2014-2015, and we carried out the monitoring of the distribution of atomic oxygen emission at 130.4 nm. The emission averaged over the distance range of 4.5-6.5 Jovian radii on the dawn and dusk sides strongly depends on the Io phase angle (IPA), and has a emission peak between IPA of 60-90 degrees on the dawn side, and between 240-270 degrees on the dusk side, respectively. It also shows the asymmetry with respect to Io's position: the intensity averaged for IPA 60-90 degrees (13.3 Rayleighs (R)) is 1.2 times greater than that for IPA 90-120 degrees (11.1 R) on the dawn side. The similar tendency is found on the dusk side. Weak atomic oxygen emission (4 R) uniformly distributes in every IPA. We also examined the radial distribution of the oxygen neutral cloud during the same period and found the emission peak near Io's orbit with decreasing the intensity toward 8.0 Jupiter radii. The results show the high density component of the oxygen neutral cloud is concentrated around Io and extends mainly toward leading side of Io. In addition, the low density neutrals uniformly exist along Io's orbit. Both components extend radially outward up to 8 Jovian radii with decreasing the density. In the presentation, we give the estimation of spatial distribution of oxygen neutral density and the oxygen ion source rate in the Io plasma torus.

Quantification of ultrasonic texture intra-heterogeneity via volumetric stochastic modeling for tissue characterization.

PubMed

Al-Kadi, Omar S; Chung, Daniel Y F; Carlisle, Robert C; Coussios, Constantin C; Noble, J Alison

2015-04-01

Intensity variations in image texture can provide powerful quantitative information about physical properties of biological tissue. However, tissue patterns can vary according to the utilized imaging system and are intrinsically correlated to the scale of analysis. In the case of ultrasound, the Nakagami distribution is a general model of the ultrasonic backscattering envelope under various scattering conditions and densities where it can be employed for characterizing image texture, but the subtle intra-heterogeneities within a given mass are difficult to capture via this model as it works at a single spatial scale. This paper proposes a locally adaptive 3D multi-resolution Nakagami-based fractal feature descriptor that extends Nakagami-based texture analysis to accommodate subtle speckle spatial frequency tissue intensity variability in volumetric scans. Local textural fractal descriptors - which are invariant to affine intensity changes - are extracted from volumetric patches at different spatial resolutions from voxel lattice-based generated shape and scale Nakagami parameters. Using ultrasound radio-frequency datasets we found that after applying an adaptive fractal decomposition label transfer approach on top of the generated Nakagami voxels, tissue characterization results were superior to the state of art. Experimental results on real 3D ultrasonic pre-clinical and clinical datasets suggest that describing tumor intra-heterogeneity via this descriptor may facilitate improved prediction of therapy response and disease characterization. Copyright © 2014 The Authors. Published by Elsevier B.V. All rights reserved.

Understanding the spatial distribution of subtidal reef assemblages in the southern Baltic Sea using towed camera platform imagery

NASA Astrophysics Data System (ADS)

Beisiegel, Kolja; Darr, Alexander; Zettler, Michael L.; Friedland, René; Gräwe, Ulf; Gogina, Mayya

2018-07-01

Quantitative sampling of sessile assemblages on temperate subtidal rocky reefs is expensive and severely time-limited by logistics. However, knowledge about distribution patterns of critical and endangered species and habitats at different spatial scales is needed for effective marine management strategies. To gain information of sessile community distribution on broader spatial scales (>1 km), visual imaging was employed for the first time on a reef complex in the south-western Baltic Sea. Analysis of 3000 images along 6 transects (in total 18 km long) from 10 to 40 m depth revealed high natural variation in reef physical structure, with well-defined changes in sessile species richness, cover and composition. Overall 14 morphological groups could be distinguished by imaging and 4 distinct community groups associated with specific habitat requirements were identified. Depth remained the best descriptor. However, data indicate that light intensity, concentration of organic carbon and suspended particulate matter have an effect on reef community distribution. Compared to fully marine conditions, the study revealed a unique zonation pattern in the circalittoral zone of the Fehmarnbelt brackish transition area, with an unexpected reef habitat in the trench. We conclude that towed camera platform imagery might help to close the information gap regarding rocky reefs in the temperate subtidal. It provides a valuable tool to assess the main distribution patterns of sessile assemblages on rough terrain, potentially applicable for management and conservation planning.

PHYSICAL PROPERTIES OF LARGE AND SMALL GRANULES IN SOLAR QUIET REGIONS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yu Daren; Xie Zongxia; Hu Qinghua

The normal mode observations of seven quiet regions obtained by the Hinode spacecraft are analyzed to study the physical properties of granules. An artificial intelligence technique is introduced to automatically find the spatial distribution of granules in feature spaces. In this work, we investigate the dependence of granular continuum intensity, mean Doppler velocity, and magnetic fields on granular diameter. We recognized 71,538 granules by an automatic segmentation technique and then extracted five properties: diameter, continuum intensity, Doppler velocity, and longitudinal and transverse magnetic flux density to describe the granules. To automatically explore the intrinsic structures of the granules in themore » five-dimensional parameter space, the X-means clustering algorithm and one-rule classifier are introduced to define the rules for classifying the granules. It is found that diameter is a dominating parameter in classifying the granules and two families of granules are derived: small granules with diameters smaller than 1.''44, and large granules with diameters larger than 1.''44. Based on statistical analysis of the detected granules, the following results are derived: (1) the averages of diameter, continuum intensity, and Doppler velocity in the upward direction of large granules are larger than those of small granules; (2) the averages of absolute longitudinal, transverse, and unsigned flux density of large granules are smaller than those of small granules; (3) for small granules, the average of continuum intensity increases with their diameters, while the averages of Doppler velocity, transverse, absolute longitudinal, and unsigned magnetic flux density decrease with their diameters. However, the mean properties of large granules are stable; (4) the intensity distributions of all granules and small granules do not satisfy Gaussian distribution, while that of large granules almost agrees with normal distribution with a peak at 1.04 I{sub 0}.« less

Influence of air-sea coupling on Indian Ocean tropical cyclones

NASA Astrophysics Data System (ADS)

Lengaigne, Matthieu; Neetu, S.; Samson, Guillaume; Vialard, Jérôme; Krishnamohan, K. S.; Masson, Sébastien; Jullien, Swen; Suresh, I.; Menkes, Christophe E.

2018-02-01

This paper assesses the impact of air-sea coupling on Indian Ocean tropical cyclones (TCs) by comparing a 20-year long simulation of a ¼° regional coupled ocean-atmosphere model with a twin experiment, where the atmospheric component is forced by sea surface temperature from the coupled simulation. The coupled simulation reproduces the observed spatio-temporal TCs distribution and TC-induced surface cooling reasonably well, but overestimates the number of TCs. Air-sea coupling does not affect the cyclogenesis spatial distribution but reduces the number of TCs by 20% and yields a better-resolved bimodal seasonal distribution in the northern hemisphere. Coupling also affects intensity distribution, inducing a four-fold decrease in the proportion of intense TCs (Cat-2 and stronger). Air-sea coupling damps TCs growth through a reduction of inner-core upward enthalpy fluxes due to the TC-induced cooling. This reduction is particularly large for the most intense TCs of the northern Indian Ocean (up to 250 W m-2), due to higher ambient surface temperatures and larger TC-induced cooling there. The negative feedback of air-sea coupling on strongest TCs is mainly associated with slow-moving storms, which spend more time over the cold wake they induce. Sensitivity experiments using a different convective parameterization yield qualitatively similar results, with a larger ( 65%) reduction in the number of TCs. Because of their relatively coarse resolution (¼°), both set of experiments however fail to reproduce the most intense observed TCs. Further studies with finer resolution models in the Bay of Bengal will be needed to assess the expectedly large impact of air-sea coupling on those intense and deadly TCs.

Failure-probability driven dose painting

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vogelius, Ivan R.; Håkansson, Katrin; Due, Anne K.

Purpose: To demonstrate a data-driven dose-painting strategy based on the spatial distribution of recurrences in previously treated patients. The result is a quantitative way to define a dose prescription function, optimizing the predicted local control at constant treatment intensity. A dose planning study using the optimized dose prescription in 20 patients is performed.Methods: Patients treated at our center have five tumor subvolumes from the center of the tumor (PET positive volume) and out delineated. The spatial distribution of 48 failures in patients with complete clinical response after (chemo)radiation is used to derive a model for tumor control probability (TCP). Themore » total TCP is fixed to the clinically observed 70% actuarial TCP at five years. Additionally, the authors match the distribution of failures between the five subvolumes to the observed distribution. The steepness of the dose–response is extracted from the literature and the authors assume 30% and 20% risk of subclinical involvement in the elective volumes. The result is a five-compartment dose response model matching the observed distribution of failures. The model is used to optimize the distribution of dose in individual patients, while keeping the treatment intensity constant and the maximum prescribed dose below 85 Gy.Results: The vast majority of failures occur centrally despite the small volumes of the central regions. Thus, optimizing the dose prescription yields higher doses to the central target volumes and lower doses to the elective volumes. The dose planning study shows that the modified prescription is clinically feasible. The optimized TCP is 89% (range: 82%–91%) as compared to the observed TCP of 70%.Conclusions: The observed distribution of locoregional failures was used to derive an objective, data-driven dose prescription function. The optimized dose is predicted to result in a substantial increase in local control without increasing the predicted risk of toxicity.« less

Spatial patterns, ecological niches, and interspecific competition of avian brood parasites: inferring from a case study of Korea.

PubMed

Lee, Jin-Won; Noh, Hee-Jin; Lee, Yunkyoung; Kwon, Young-Soo; Kim, Chang-Hoe; Yoo, Jeong-Chil

2014-09-01

Since obligate avian brood parasites depend completely on the effort of other host species for rearing their progeny, the availability of hosts will be a critical resource for their life history. Circumstantial evidence suggests that intense competition for host species may exist not only within but also between species. So far, however, few studies have demonstrated whether the interspecific competition really occurs in the system of avian brood parasitism and how the nature of brood parasitism is related to their niche evolution. Using the occurrence data of five avian brood parasites from two sources of nationwide bird surveys in South Korea and publically available environmental/climatic data, we identified their distribution patterns and ecological niches, and applied species distribution modeling to infer the effect of interspecific competition on their spatial distribution. We found that the distribution patterns of five avian brood parasites could be characterized by altitude and climatic conditions, but overall their spatial ranges and ecological niches extensively overlapped with each other. We also found that the predicted distribution areas of each species were generally comparable to the realized distribution areas, and the numbers of individuals in areas where multiple species were predicted to coexist showed positive relationships among species. In conclusion, despite following different coevolutionary trajectories to adapt to their respect host species, five species of avian brood parasites breeding in South Korea occupied broadly similar ecological niches, implying that they tend to conserve ancestral preferences for ecological conditions. Furthermore, our results indicated that contrary to expectation interspecific competition for host availability between avian brood parasites seemed to be trivial, and thus, play little role in shaping their spatial distributions and ecological niches. Future studies, including the complete ranges of avian brood parasites and ecological niches of host species, will be worthwhile to further elucidate these issues.

Evaluating the intensity of fire at the Acheulian site of Gesher Benot Ya'aqov-Spatial and thermoluminescence analyses.

PubMed

Alperson-Afil, Nira; Richter, Daniel; Goren-Inbar, Naama

2017-01-01

This manuscript presents an attempt to evaluate the intensity of fire through spatial patterning and thermoluminescence methodology. Previous studies of Layer II-6 Level 2 at the Acheulian site of Gesher Benot Ya'aqov suggested that hominins differentiated their activities across space, including multiple activities around a hearth reconstructed on the basis of the distribution of burned flint artifacts. A transect of ~4 m was extended from the center of the reconstructed hearth of Level 2 to its periphery in order to examine the intensity of fire. Burned and unburned flint microartifacts were sampled along this transect. The results of earlier and current thermoluminescence (TL) analysis demonstrate a general agreement with the macroscopic determination of burning, indicating that the possibility of misinterpretation based on macroscopic observations is negligible. The TL signal from flint microartifacts close to the hearth's center shows unambiguous signs of strong heating, whereas with increasing distance from the hearth the TL signal can be interpreted as a result of decreasing temperatures and/or shorter durations of exposure to fire in addition to a decreasing number of flints showing fire damage. Our study shows that TL analysis can identify some variation in fire intensity, which allows a more precise classification of burned flint microartifacts with respect to their heating history.

Randomly displaced phase distribution design and its advantage in page-data recording of Fourier transform holograms.

PubMed

Emoto, Akira; Fukuda, Takashi

2013-02-20

For Fourier transform holography, an effective random phase distribution with randomly displaced phase segments is proposed for obtaining a smooth finite optical intensity distribution in the Fourier transform plane. Since unitary phase segments are randomly distributed in-plane, the blanks give various spatial frequency components to an image, and thus smooth the spectrum. Moreover, by randomly changing the phase segment size, spike generation from the unitary phase segment size in the spectrum can be reduced significantly. As a result, a smooth spectrum including sidebands can be formed at a relatively narrow extent. The proposed phase distribution sustains the primary functions of a random phase mask for holographic-data recording and reconstruction. Therefore, this distribution is expected to find applications in high-density holographic memory systems, replacing conventional random phase mask patterns.

Electromagnetic Design of a Magnetically Coupled Spatial Power Combiner

NASA Astrophysics Data System (ADS)

Bulcha, B. T.; Cataldo, G.; Stevenson, T. R.; U-Yen, K.; Moseley, S. H.; Wollack, E. J.

2018-04-01

The design of a two-dimensional spatial beam-combining network employing a parallel-plate superconducting waveguide filled with a monocrystalline silicon dielectric substrate is presented. This component uses arrays of magnetically coupled antenna elements to achieve high coupling efficiency and full sampling of the intensity distribution while avoiding diffractive losses in the multimode waveguide region. These attributes enable the structure's use in realizing compact far-infrared spectrometers for astrophysical and instrumentation applications. If unterminated, reflections within a finite-sized spatial beam combiner can potentially lead to spurious couplings between elements. A planar meta-material electromagnetic absorber is implemented to control this response within the device. This broadband termination absorbs greater than 0.99 of the power over the 1.7:1 operational band at angles ranging from normal to near-parallel incidence. The design approach, simulations and applications of the spatial power combiner and meta-material termination structure are presented.

Creation of diffraction-limited non-Airy multifocal arrays using a spatially shifted vortex beam

NASA Astrophysics Data System (ADS)

Lin, Han; Gu, Min

2013-02-01

Diffraction-limited non-Airy multifocal arrays are created by focusing a phase-modulated vortex beam through a high numerical-aperture objective. The modulated phase at the back aperture of the objective resulting from the superposition of two concentric phase-modulated vortex beams allows for the generation of a multifocal array of cylindrically polarized non-Airy patterns. Furthermore, we shift the spatial positions of the phase vortices to manipulate the intensity distribution at each focal spot, leading to the creation of a multifocal array of split-ring patterns. Our method is experimentally validated by generating the predicted phase modulation through a spatial light modulator. Consequently, the spatially shifted circularly polarized vortex beam adopted in a dynamic laser direct writing system facilitates the fabrication of a split-ring microstructure array in a polymer material by a single exposure of a femtosecond laser beam.

Intensification and spatial homogenization of coastal upwelling under climate change.

PubMed

Wang, Daiwei; Gouhier, Tarik C; Menge, Bruce A; Ganguly, Auroop R

2015-02-19

The timing and strength of wind-driven coastal upwelling along the eastern margins of major ocean basins regulate the productivity of critical fisheries and marine ecosystems by bringing deep and nutrient-rich waters to the sunlit surface, where photosynthesis can occur. How coastal upwelling regimes might change in a warming climate is therefore a question of vital importance. Although enhanced land-ocean differential heating due to greenhouse warming has been proposed to intensify coastal upwelling by strengthening alongshore winds, analyses of observations and previous climate models have provided little consensus on historical and projected trends in coastal upwelling. Here we show that there are strong and consistent changes in the timing, intensity and spatial heterogeneity of coastal upwelling in response to future warming in most Eastern Boundary Upwelling Systems (EBUSs). An ensemble of climate models shows that by the end of the twenty-first century the upwelling season will start earlier, end later and become more intense at high but not low latitudes. This projected increase in upwelling intensity and duration at high latitudes will result in a substantial reduction of the existing latitudinal variation in coastal upwelling. These patterns are consistent across three of the four EBUSs (Canary, Benguela and Humboldt, but not California). The lack of upwelling intensification and greater uncertainty associated with the California EBUS may reflect regional controls associated with the atmospheric response to climate change. Given the strong linkages between upwelling and marine ecosystems, the projected changes in the intensity, timing and spatial structure of coastal upwelling may influence the geographical distribution of marine biodiversity.

Dynamics of low- and high-Z metal ions emitted during nanosecond laser-produced plasmas

NASA Astrophysics Data System (ADS)

Elsied, Ahmed M.; Diwakar, Prasoon K.; Polek, Mathew; Hassanein, Ahmed

2016-11-01

Dynamics of metal ions during laser-produced plasmas was studied. A 1064 nm, Nd: YAG laser pulse was used to ablate pure Al, Fe, Co, Mo, and Sn samples. Ion flux and velocity were measured using Faraday cup ion collector. Time-of-flight measurements showed decreasing ion flux and ion velocity with increasing atomic weight, and heavy metal ion flux profile exhibited multiple peaks that was not observed in lighter metals. Slow peak was found to follow shifted Maxwell Boltzmann distribution, while the fast peak was found to follow Gaussian distribution. Ion flux angular distribution that was carried out on Mo and Al using fixed laser intensity 2.5 × 1010 W/cm2 revealed that the slow ion flux peaks at small angles, that is, close to normal to the target ˜0° independent of target's atomic weight, and fast ion flux for Mo peaks at large angles ˜40° measured from the target normal, while it completely absents for Al. This difference in spatial and temporal distribution reveals that the emission mechanism of the fast and slow ions is different. From the slow ion flux angular distribution, the measured plume expansion ratio (plume forward peaking) was 1.90 and 2.10 for Al and Mo, respectively. Moreover, the effect of incident laser intensity on the ion flux emission as well as the emitted ion velocity were investigated using laser intensities varying from 2.5 × 1010 W/cm2 to 1.0 × 1011 W/cm2. Linear increase of fast ion flux and velocity, and quadratic increase of slow ion flux and velocity were observed. For further understanding of plume dynamics, laser optical emission spectroscopy was used to characterize Sn plasma by measuring the temporal and spatial evolution of plasma electron density Ne and electron temperature Te. At 3.5 mm away from the target, plasma density showed slow decrease with time, however electron temperature was observed to decrease dramatically. The maximum plasma density and temperature occurred at 0.5 mm away from target and were measured to be 8.0 × 1017 cm-3 and 1.3 eV, respectively.

Spatially resolved density and ionization measurements of shocked foams using x-ray fluorescence

DOE Office of Scientific and Technical Information (OSTI.GOV)

MacDonald, M. J.; Keiter, P. A.; Montgomery, D. S.

2016-09-22

We present experiments at the Trident laser facility demonstrating the use of x-ray fluorescence (XRF) to simultaneously measure density, ionization state populations, and electron temperature in shocked foams. An imaging x-ray spectrometer was used to obtain spatially-resolved measurements of Ti K-more » $$\\alpha$$ emission. Density profiles were measured from K-$$\\alpha$$ intensity. Ti ionization state distributions and electron temperatures were inferred by fitting K-$$\\alpha$$ spectra to spectra from CRETIN simulations. This study shows that XRF provides a powerful tool to complement other diagnostics to make equation of state measurements of shocked materials containing a suitable tracer element.« less

Epicentral Determination from Macroseismic Data: Insights from Four Centuries of Observations (Invited)

NASA Astrophysics Data System (ADS)

Szeliga, W. M.; Martin, S.; Hough, S.; Bilham, R.

2009-12-01

A new compilation of more than 8300 newly interpreted intensity observations from 570 earthquakes on the Indian subcontinent between 1636 and 2009 provides a rich data base for examining the utility of recently developed methods for deriving magnitude and location from macroseismic data. Instrumentally determined locations and magnitudes are available for 144 of these earthquakes since 1900, and for a subset of these earthquakes we can calculate differences between instrumental- and intensity-derived parameters. Using a modification of the Bakun and Wentworth (1997) algorithm we find that epicenters determined from well-conditioned intensity distributions are typically within one fault length of those determined from instrumental data. This encouraging result, however, applies to fewer than one third of the events. For a larger number of earthquakes, intensity-derived epicenters are poorly constrained, due to scatter in intensity amplitude and/or to poor spatial coverage. This raises concerns about the accuracy of rupture parameters determined for pre-instrumental earthquakes in India and elsewhere. We find moreover, that where dense spatial intensity values are available, location is recovered reasonably well (e.g. Bhuj 2001, Kashmir 2005), but magnitude is over-estimated by as much as one magnitude unit. This suggests that epicentral locations for well-documented M>7 historical earthquakes might be relatively reliable, but their magnitude might be significantly inflated. The cause for these erroneous locations and magnitudes are examined and we outline the results of our search for numerical rules to determine whether a given set of intensities will provide accurate or misleading results.

Comparison of spatially and temporally resolved diffuse transillumination measurement systems for extraction of optical properties of scattering media.

PubMed

Ortiz-Rascón, E; Bruce, N C; Garduño-Mejía, J; Carrillo-Torres, R; Hernández-Paredes, J; Álvarez-Ramos, M E

2017-11-20

This paper discusses the main differences between two different methods for determining the optical properties of tissue optical phantoms by fitting the spatial and temporal intensity distribution functions to the diffusion approximation theory. The consistency in the values of the optical properties is verified by changing the width of the recipient containing the turbid medium; as the optical properties are an intrinsic value of the scattering medium, independently of the recipient width, the stability in these values for different widths implies a better measurement system for the acquisition of the optical properties. It is shown that the temporal fitting method presents higher stability than the spatial fitting method; this is probably due to the addition of the time of flight parameter into the diffusion theory.

Coulomb-driven energy boost of heavy ions for laser-plasma acceleration.

PubMed

Braenzel, J; Andreev, A A; Platonov, K; Klingsporn, M; Ehrentraut, L; Sandner, W; Schnürer, M

2015-03-27

An unprecedented increase of kinetic energy of laser accelerated heavy ions is demonstrated. Ultrathin gold foils have been irradiated by an ultrashort laser pulse at a peak intensity of 8×10^{19}  W/  cm^{2}. Highly charged gold ions with kinetic energies up to >200  MeV and a bandwidth limited energy distribution have been reached by using 1.3 J laser energy on target. 1D and 2D particle in cell simulations show how a spatial dependence on the ion's ionization leads to an enhancement of the accelerating electrical field. Our theoretical model considers a spatial distribution of the ionization inside the thin target, leading to a field enhancement for the heavy ions by Coulomb explosion. It is capable of explaining the energy boost of highly charged ions, enabling a higher efficiency for the laser-driven heavy ion acceleration.

A parallel-processing approach to computing for the geographic sciences

USGS Publications Warehouse

Crane, Michael; Steinwand, Dan; Beckmann, Tim; Krpan, Greg; Haga, Jim; Maddox, Brian; Feller, Mark

2001-01-01

The overarching goal of this project is to build a spatially distributed infrastructure for information science research by forming a team of information science researchers and providing them with similar hardware and software tools to perform collaborative research. Four geographically distributed Centers of the U.S. Geological Survey (USGS) are developing their own clusters of low-cost personal computers into parallel computing environments that provide a costeffective way for the USGS to increase participation in the high-performance computing community. Referred to as Beowulf clusters, these hybrid systems provide the robust computing power required for conducting research into various areas, such as advanced computer architecture, algorithms to meet the processing needs for real-time image and data processing, the creation of custom datasets from seamless source data, rapid turn-around of products for emergency response, and support for computationally intense spatial and temporal modeling.

High throughput dual-wavelength temperature distribution imaging via compressive imaging

NASA Astrophysics Data System (ADS)

Yao, Xu-Ri; Lan, Ruo-Ming; Liu, Xue-Feng; Zhu, Ge; Zheng, Fu; Yu, Wen-Kai; Zhai, Guang-Jie

2018-03-01

Thermal imaging is an essential tool in a wide variety of research areas. In this work we demonstrate high-throughput double-wavelength temperature distribution imaging using a modified single-pixel camera without the requirement of a beam splitter (BS). A digital micro-mirror device (DMD) is utilized to display binary masks and split the incident radiation, which eliminates the necessity of a BS. Because the spatial resolution is dictated by the DMD, this thermal imaging system has the advantage of perfect spatial registration between the two images, which limits the need for the pixel registration and fine adjustments. Two bucket detectors, which measures the total light intensity reflected from the DMD, are employed in this system and yield an improvement in the detection efficiency of the narrow-band radiation. A compressive imaging algorithm is utilized to achieve under-sampling recovery. A proof-of-principle experiment was presented to demonstrate the feasibility of this structure.

Dark field photoelectron emission microscopy of micron scale few layer graphene

NASA Astrophysics Data System (ADS)

Barrett, N.; Conrad, E.; Winkler, K.; Krömker, B.

2012-08-01

We demonstrate dark field imaging in photoelectron emission microscopy (PEEM) of heterogeneous few layer graphene (FLG) furnace grown on SiC(000-1). Energy-filtered, threshold PEEM is used to locate distinct zones of FLG graphene. In each region, selected by a field aperture, the k-space information is imaged using appropriate transfer optics. By selecting the photoelectron intensity at a given wave vector and using the inverse transfer optics, dark field PEEM gives a spatial distribution of the angular photoelectron emission. In the results presented here, the wave vector coordinates of the Dirac cones characteristic of commensurate rotations of FLG on SiC(000-1) are selected providing a map of the commensurate rotations across the surface. This special type of contrast is therefore a method to map the spatial distribution of the local band structure and offers a new laboratory tool for the characterisation of technically relevant, microscopically structured matter.

Double-Referential Holography and Spatial Quadrature Amplitude Modulation

NASA Astrophysics Data System (ADS)

Zukeran, Keisuke; Okamoto, Atsushi; Takabayashi, Masanori; Shibukawa, Atsushi; Sato, Kunihiro; Tomita, Akihisa

2013-09-01

We proposed a double-referential holography (DRH) that allows phase-detection without external additional beams. In the DRH, phantom beams, prepared in the same optical path as signal beams and preliminary multiplexed in a recording medium along with the signal, are used to produce interference fringes on an imager for converting a phase into an intensity distribution. The DRH enables stable and high-accuracy phase detection independent of the fluctuations and vibrations of the optical system owing to medium shift and temperature variation. Besides, the collinear arrangement of the signal and phantom beams leads to the compactness of the optical data storage system. We conducted an experiment using binary phase modulation signals for verifying the DRH operation. In addition, 38-level spatial quadrature amplitude modulation signals were successfully reproduced with the DRH by numerical simulation. Furthermore, we verified that the distributed phase-shifting method moderates the dynamic range consumption for the exposure of phantom beams.

Generation of spiral optical beams using a spatial light modulator

NASA Astrophysics Data System (ADS)

Rodrigo, Peter J.; Alonzo, Carlo A.; Gluckstad, Jesper

2005-08-01

Recently, a new type of beam termed "spiral optical beam" has been introduced [Alonzo, et al., Opt. Express 13, 1749 (2005)]. Spiral beams are created from multiplicative mixtures of helical and conical phase distributions. Helico-conical phase fronts that generate these novel beams are not achieved with a sequence of a corkscrew wave-plate and an axicon (as this sequence gives a sum of helical and conical phase terms). Nevertheless, the availability of phase-only spatial light modulators (SLM) allows one to directly imprint helico-conical phase functions on an incident plane wave and provides an easy way to modify the profile of the encoded phase. Focusing the phase-modified field results in spiral intensity distributions that may find use for optical manipulation of mesoscopic particles. In this paper, we have extended the discussion to translation and rotation (as well as chirality switching) of the spiral beams using SLM control.

Engineered surface scatterers in edge-lit slab waveguides to improve light delivery in algae cultivation.

PubMed

Ahsan, Syed Saad; Pereyra, Brandon; Jung, Erica E; Erickson, David

2014-10-20

Most existing photobioreactors do a poor job of distributing light uniformly due to shading effects. One method by which this could be improved is through the use of internal wave-guiding structures incorporating engineered light scattering schemes. By varying the density of these scatterers, one can control the spatial distribution of light inside the reactor enabling better uniformity of illumination. Here, we compare a number of light scattering schemes and evaluate their ability to enhance biomass accumulation. We demonstrate a design for a gradient distribution of surface scatterers with uniform lateral scattering intensity that is superior for algal biomass accumulation, resulting in a 40% increase in the growth rate.

The Use of Convolutional Neural Network in Relating Precipitation to Circulation

NASA Astrophysics Data System (ADS)

Pan, B.; Hsu, K. L.; AghaKouchak, A.; Sorooshian, S.

2017-12-01

Precipitation prediction in dynamical weather and climate models depends on 1) the predictability of pressure or geopotential height for the forecasting period and 2) the successive work of interpreting the pressure field in terms of precipitation events. The later task is represented as parameterization schemes in numerical models, where detailed computing inevitably blurs the hidden cause-and-effect relationship in precipitation generation. The "big data" provided by numerical simulation, reanalysis and observation networks requires better causation analysis for people to digest and realize their use. While classic synoptical analysis methods are very-often insufficient for spatially distributed high dimensional data, a Convolutional Neural Network(CNN) is developed here to directly relate precipitation with circulation. Case study carried over west coast United States during boreal winter showed that CNN can locate and capture key pressure zones of different structures to project precipitation spatial distribution with high accuracy across hourly to monthly scales. This direct connection between atmospheric circulation and precipitation offers a probe for attributing precipitation to the coverage, location, intensity and spatial structure of characteristic pressure zones, which can be used for model diagnosis and improvement.

[Multiple time scales analysis of spatial differentiation characteristics of non-point source nitrogen loss within watershed].

PubMed

Liu, Mei-bing; Chen, Xing-wei; Chen, Ying

2015-07-01

Identification of the critical source areas of non-point source pollution is an important means to control the non-point source pollution within the watershed. In order to further reveal the impact of multiple time scales on the spatial differentiation characteristics of non-point source nitrogen loss, a SWAT model of Shanmei Reservoir watershed was developed. Based on the simulation of total nitrogen (TN) loss intensity of all 38 subbasins, spatial distribution characteristics of nitrogen loss and critical source areas were analyzed at three time scales of yearly average, monthly average and rainstorms flood process, respectively. Furthermore, multiple linear correlation analysis was conducted to analyze the contribution of natural environment and anthropogenic disturbance on nitrogen loss. The results showed that there were significant spatial differences of TN loss in Shanmei Reservoir watershed at different time scales, and the spatial differentiation degree of nitrogen loss was in the order of monthly average > yearly average > rainstorms flood process. TN loss load mainly came from upland Taoxi subbasin, which was identified as the critical source area. At different time scales, land use types (such as farmland and forest) were always the dominant factor affecting the spatial distribution of nitrogen loss, while the effect of precipitation and runoff on the nitrogen loss was only taken in no fertilization month and several processes of storm flood at no fertilization date. This was mainly due to the significant spatial variation of land use and fertilization, as well as the low spatial variability of precipitation and runoff.

Using Moran's I and GIS to study spatial pattern of forest litter carbon density in typical subtropical region, China

NASA Astrophysics Data System (ADS)

Fu, W. J.; Jiang, P. K.; Zhou, G. M.; Zhao, K. L.

2013-12-01

The spatial variation of forest litter carbon (FLC) density in the typical subtropical forests in southeast China was investigated using Moran's I, geostatistics and a geographical information system (GIS). A total of 839 forest litter samples were collected based on a 12 km (South-North) × 6 km (East-West) grid system in Zhejiang Province. Forest litter carbon density values were very variable, ranging from 10.2 kg ha-1 to 8841.3 kg ha-1, with an average of 1786.7 kg ha-1. The aboveground biomass had the strongest positive correlation with FLC density, followed by forest age and elevation. Global Moran's I revealed that FLC density had significant positive spatial autocorrelation. Clear spatial patterns were observed using Local Moran's I. A spherical model was chosen to fit the experimental semivariogram. The moderate "nugget-to-sill" (0.536) value revealed that both natural and anthropogenic factors played a key role in spatial heterogeneity of FLC density. High FLC density values were mainly distributed in northwestern and western part of Zhejiang province, which were related to adopting long-term policy of forest conservation in these areas. While Hang-Jia-Hu (HJH) Plain, Jin-Qu (JQ) basin and coastal areas had low FLC density due to low forest coverage and intensive management of economic forests. These spatial patterns in distribution map were in line with the spatial-cluster map described by local Moran's I. Therefore, Moran's I, combined with geostatistics and GIS could be used to study spatial patterns of environmental variables related to forest ecosystem.

Theoretical studies to elucidate the influence of magnetic dipolar interactions occurring in the magnetic nanoparticle systems, for biomedical applications

NASA Astrophysics Data System (ADS)

Osaci, M.; Cacciola, M.

2016-02-01

In recent years, the study of magnetic nanoparticles has been intensively developed not only for their fundamental theoretical interest, but also for their many technological applications, especially biomedical applications, ranging from contrast agents for magnetic resonance imaging to the deterioration of cancer cells via hyperthermia treatment. The theoretical and experimental research has shown until now that the magnetic dipolar interactions between nanoparticles can have a significant influence on the magnetic behaviour of the system. But, this influence is not well understood. It is clear that the magnetic dipolar interaction intensity is correlated with the nanoparticle concentration, volume fraction and magnetic moment orientations. In this paper, we try to understand the influence of magnetic dipolar interactions on the behaviour of magnetic nanoparticle systems, for biomedical applications. For the model, we considered spherical nanoparticles with uniaxial anisotropy and lognormal distribution of the sizes. The model involves a simulation stage of the spatial distribution and orientation of the nanoparticles and their easy axes of magnetic anisotropy, and an evaluation stage of the Néel relaxation time. To assess the Néel relaxation time, we are going to discretise and adapt, to the local magnetic field, the Coffey analytical solution for the equation Fokker-Planck describing the dynamics of magnetic moments of nanoparticles in oblique external magnetic field. There are three fundamental aspects of interest in our studies on the magnetic nanoparticles: their spatial & orientational distributions, concentrations and sizes.

Monitoring of fluid motion in a micromixer by dynamic NMR microscopy.

PubMed

Ahola, Susanna; Casanova, Federico; Perlo, Juan; Münnemann, Kerstin; Blümich, Bernhard; Stapf, Siegfried

2006-01-01

The velocity distribution of liquid flowing in a commercial micromixer has been determined directly by using pulsed-field gradient NMR. Velocity maps with a spatial resolution of 29 microm x 43 microm were obtained by combining standard imaging gradient units with a homebuilt rectangular surface coil matching the mixer geometry. The technique provides access to mixers and reactors of arbitrary shape regardless of optical transparency. Local heterogeneities in the signal intensity and the velocity pattern were found and serve to investigate the quality and functionality of a micromixer, revealing clogging and inhomogeneous flow distributions.

Multicomponent 'dark' cnoidal waves: stability and soliton asymptotes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vysloukh, Victor A; Petnikova, V M; Rudenko, K V

1999-07-31

The problem of steady-state propagation of several mutually incoherent optical waves - components of 'dark' multicomponent solitons and cnoidal waves - through a photorefractive crystal with a drift nonlinearity of the defocusing type is considered and solved. Analytical expressions are obtained for the distributions of the optical field between the components of the resulting solutions, containing up to three self-consistent components inclusive. It is shown that these solutions are stable and that their spatial structure is retained in mutual collisions and after stochastic perturbations of the intensity distributions. (this issue is dedicated to the memory of s a akhmanov)

Distributed dynamic large strain optical fiber sensor based on the detection of spontaneous Brillouin scattering.

PubMed

Masoudi, Ali; Belal, Mohammad; Newson, Trevor P

2013-09-01

A Brillouin-based distributed optical fiber dynamic strain sensor is described which converts strain-induced Brillouin frequency shift into optical intensity variations by using an imbalanced Mach-Zhender interferometer. A 3×3 coupler is used at the output of this interferometer to permit differentiate and cross multiply demodulation. The demonstrated sensor is capable of probing dynamic strain disturbances over 2 km of sensing length every 0.5 s up to a strain of 10 mε with an accuracy of ±50 με and spatial resolution of 1.3 m.

Distributed optical fiber dynamic magnetic field sensor based on magnetostriction.

PubMed

Masoudi, Ali; Newson, Trevor P

2014-05-01

A distributed optical fiber sensor is introduced which is capable of quantifying multiple magnetic fields along a 1 km sensing fiber with a spatial resolution of 1 m. The operation of the proposed sensor is based on measuring the magnetorestrictive induced strain of a nickel wire attached to an optical fiber. The strain coupled to the optical fiber was detected by measuring the strain-induced phase variation between the backscattered Rayleigh light from two segments of the sensing fiber. A magnetic field intensity resolution of 0.3 G over a bandwidth of 50-5000 Hz was demonstrated.

Experimental studies of a continuous-wave HF(DF) confocal unstable resonator. Interim report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chodzko, R.A.; Cross, E.F.; Durran, D.A.

1976-05-03

A series of experiments were performed on a continuous-wave HF(DF) multiline edge-coupled confocal unstable resonator at The Aerospace Corporation MESA facility. Experimental techniques were developed to measure remotely (from a blockhouse) the output power, the near-field intensity distribution, the spatially resolved spectral content of the near field, and the far-field power distribution. A new technique in which a variable aperture calorimeter absorbing scraper (VACAS) was used for measuring the continuous-wave output power from an unstable resonator with variable-mode geometry and without the use of an output coupling mirror was developed. (GRA)

The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire

NASA Astrophysics Data System (ADS)

Murphy, Sheila F.; Writer, Jeffrey H.; Blaine McCleskey, R.; Martin, Deborah A.

2015-08-01

Storms following wildfires are known to impair drinking water supplies in the southwestern United States, yet our understanding of the role of precipitation in post-wildfire water quality is far from complete. We quantitatively assessed water-quality impacts of different hydrologic events in the Colorado Front Range and found that for a three-year period, substantial hydrologic and geochemical responses downstream of a burned area were primarily driven by convective storms with a 30 min rainfall intensity >10 mm h-1. These storms, which typically occur several times each year in July-September, are often small in area, short-lived, and highly variable in intensity and geographic distribution. Thus, a rain gage network with high temporal resolution and spatial density, together with high-resolution stream sampling, are required to adequately characterize post-wildfire responses. We measured total suspended sediment, dissolved organic carbon (DOC), nitrate, and manganese concentrations that were 10-156 times higher downstream of a burned area compared to upstream during relatively common (50% annual exceedance probability) rainstorms, and water quality was sufficiently impaired to pose water-treatment concerns. Short-term water-quality impairment was driven primarily by increased surface runoff during higher intensity convective storms that caused erosion in the burned area and transport of sediment and chemical constituents to streams. Annual sediment yields downstream of the burned area were controlled by storm events and subsequent remobilization, whereas DOC yields were closely linked to annual runoff and thus were more dependent on interannual variation in spring runoff. Nitrate yields were highest in the third year post-wildfire. Results from this study quantitatively demonstrate that water quality can be altered for several years after wildfire. Because the southwestern US is prone to wildfires and high-intensity rain storms, the role of storms in post-wildfire water-quality impacts must be considered when assessing water-quality vulnerability.

The role of precipitation type, intensity, and spatial distribution in source water quality after wildfire

USGS Publications Warehouse

Murphy, Sheila F.; Writer, Jeffrey H.; McCleskey, R. Blaine; Martin, Deborah A.

2015-01-01

Storms following wildfires are known to impair drinking water supplies in the southwestern United States, yet our understanding of the role of precipitation in post-wildfire water quality is far from complete. We quantitatively assessed water-quality impacts of different hydrologic events in the Colorado Front Range and found that for a three-year period, substantial hydrologic and geochemical responses downstream of a burned area were primarily driven by convective storms with a 30 min rainfall intensity >10 mm h−1. These storms, which typically occur several times each year in July–September, are often small in area, short-lived, and highly variable in intensity and geographic distribution. Thus, a rain gage network with high temporal resolution and spatial density, together with high-resolution stream sampling, are required to adequately characterize post-wildfire responses. We measured total suspended sediment, dissolved organic carbon (DOC), nitrate, and manganese concentrations that were 10–156 times higher downstream of a burned area compared to upstream during relatively common (50% annual exceedance probability) rainstorms, and water quality was sufficiently impaired to pose water-treatment concerns. Short-term water-quality impairment was driven primarily by increased surface runoff during higher intensity convective storms that caused erosion in the burned area and transport of sediment and chemical constituents to streams. Annual sediment yields downstream of the burned area were controlled by storm events and subsequent remobilization, whereas DOC yields were closely linked to annual runoff and thus were more dependent on interannual variation in spring runoff. Nitrate yields were highest in the third year post-wildfire. Results from this study quantitatively demonstrate that water quality can be altered for several years after wildfire. Because the southwestern US is prone to wildfires and high-intensity rain storms, the role of storms in post-wildfire water-quality impacts must be considered when assessing water-quality vulnerability.

Climate change and natural disasters – integrating science and practice to protect health

PubMed Central

Sauerborn, Rainer; Ebi, Kristie

2012-01-01

Background Hydro-meteorological disasters are the focus of this paper. The authors examine, to which extent climate change increases their frequency and intensity. Methods Review of IPCC-projections of climate-change related extreme weather events and related literature on health effects. Results Projections show that climate change is likely to increase the frequency, intensity, duration, and spatial distribution of a range of extreme weather events over coming decades. Conclusions There is a need for strengthened collaboration between climate scientists, the health researchers and policy-makers as well as the disaster community to jointly develop adaptation strategies to protect human. PMID:23273248

Insights into metals in individual fine particles from municipal solid waste using synchrotron radiation-based micro-analytical techniques.

PubMed

Zhu, Yumin; Zhang, Hua; Shao, Liming; He, Pinjing

2015-01-01

Excessive inter-contamination with heavy metals hampers the application of biological treatment products derived from mixed or mechanically-sorted municipal solid waste (MSW). In this study, we investigated fine particles of <2mm, which are small fractions in MSW but constitute a significant component of the total heavy metal content, using bulk detection techniques. A total of 17 individual fine particles were evaluated using synchrotron radiation-based micro-X-ray fluorescence and micro-X-ray diffraction. We also discussed the association, speciation and source apportionment of heavy metals. Metals were found to exist in a diffuse distribution with heterogeneous intensities and intense hot-spots of <10 μm within the fine particles. Zn-Cu, Pb-Fe and Fe-Mn-Cr had significant correlations in terms of spatial distribution. The overlapped enrichment, spatial association, and the mineral phases of metals revealed the potential sources of fine particles from size-reduced waste fractions (such as scraps of organic wastes or ceramics) or from the importation of other particles. The diverse sources of heavy metal pollutants within the fine particles suggested that separate collection and treatment of the biodegradable waste fraction (such as food waste) is a preferable means of facilitating the beneficial utilization of the stabilized products. Copyright © 2014. Published by Elsevier B.V.

Simultaneous measurements of the hydrogen airglow emissions of Lyman alpha, Lyman beta, and Balmer alpha.

NASA Technical Reports Server (NTRS)

Weller, C. S.; Meier, R. R.; Tinsley, B. A.

1971-01-01

Comparison of Lyman-alpha, 740- to 1050-A, and Balmer-alpha airglow measurements made at 134 deg solar-zenith angle on Oct. 13, 1969, with resonance-scattering models of solar radiation. Model comparison with Lyman-alpha data fixes the hydrogen column abundance over 215 km to 2 x 10 to the 13th per cu cm within a factor of 2. Differences between the Lyman-alpha model and data indicate a polar-equatorial departure from spherical symmetry in the hydrogen distribution. A Lyman-beta model based on the hydrogen distribution found to fit the Lyman-alpha data fits the spatial variation of the 740- to 1050-A data well from 100 to 130 km, but it does not fit the data well at higher altitudes; thus the presence of more rapidly absorbed shorter-wavelength radiation is indicated. This same resonance-scattering model yields Balmer-alpha intensities that result in good spatial agreement with the Balmer-alpha measurements, but a fivefold increase in the measured solar line center Lyman-beta flux is required (as required for the Lyman-beta measurement). The intensity ratio of Lyman-beta and Balmer-alpha at night is found to be a simple measure of the hydrogen optical depth if measurements with good accuracy can be made in the visible and ultraviolet spectrum.

Temporal and spatial evolution of nanosecond microwave-driven plasma

NASA Astrophysics Data System (ADS)

Chang, C.; Chen, X. Q.; Zhu, M.; Pu, Y. K.

2018-06-01

In this paper, a method for simultaneously acquiring the temporal and spatial evolution of characteristic plasma spectra in a single microwave pulse is proposed and studied. By using multi-sub-beam fiber bundles coupled with a spectrometer and EMICCD (Electron-multiplying intensified charge-coupled device), the spatial distribution and time evolution of characteristic spectra of desorbed gases at the dielectric/vacuum interface during nanosecond microwave-driven plasma discharge are observed. Arrays of small align tubes punctured with metal walls of feed horn are filled with separate fibers of matched sizes and equal lengths. The output ends of fibers arranged in a single longitudinal column are connected to the entrance slit of a spectrometer, where the optical spectrum inputs to a high-speed EMICCD, to detect the rapid-varying time and space spectra of nanosecond giga-watt microwave discharges. The evolution of spectral clusters of N2 (C-B), N2+ (B-X), and the hydrogen atoms is discovered and monitored. The whole duration of light emission is much longer than the microwave pulse, and the intensities of ion N2+ (B-X) spectra increase after microwave pulses with rise times of 25-50 ns. The brightness distribution of plasma spectra in different space is observed and approximately consistent with the simulated E-field distribution.

Considerations in the use of fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy to characterize rumen methanogens and define their spatial distributions.

PubMed

Valle, Edith R; Henderson, Gemma; Janssen, Peter H; Cox, Faith; Alexander, Trevor W; McAllister, Tim A

2015-06-01

In this study, methanogen-specific coenzyme F420 autofluorescence and confocal laser scanning microscopy were used to identify rumen methanogens and define their spatial distribution in free-living, biofilm-, and protozoa-associated microenvironments. Fluorescence in situ hybridization (FISH) with temperature-controlled hybridization was used in an attempt to describe methanogen diversity. A heat pretreatment (65 °C, 1 h) was found to be a noninvasive method to increase probe access to methanogen RNA targets. Despite efforts to optimize FISH, 16S rRNA methanogen-specific probes, including Arch915, bound to some cells that lacked F420, possibly identifying uncharacterized Methanomassiliicoccales or reflecting nonspecific binding to other members of the rumen bacterial community. A probe targeting RNA from the methanogenesis-specific methyl coenzyme M reductase (mcr) gene was shown to detect cultured Methanosarcina cells with signal intensities comparable to those of 16S rRNA probes. However, the probe failed to hybridize with the majority of F420-emitting rumen methanogens, possibly because of differences in cell wall permeability among methanogen species. Methanogens were shown to integrate into microbial biofilms and to exist as ecto- and endosymbionts with rumen protozoa. Characterizing rumen methanogens and defining their spatial distribution may provide insight into mitigation strategies for ruminal methanogenesis.

Lung Parenchymal Signal Intensity in MRI: A Technical Review with Educational Aspirations Regarding Reversible Versus Irreversible Transverse Relaxation Effects in Common Pulse Sequences.

PubMed

Mulkern, Robert; Haker, Steven; Mamata, Hatsuho; Lee, Edward; Mitsouras, Dimitrios; Oshio, Koichi; Balasubramanian, Mukund; Hatabu, Hiroto

2014-03-01

Lung parenchyma is challenging to image with proton MRI. The large air space results in ~l/5th as many signal-generating protons compared to other organs. Air/tissue magnetic susceptibility differences lead to strong magnetic field gradients throughout the lungs and to broad frequency distributions, much broader than within other organs. Such distributions have been the subject of experimental and theoretical analyses which may reveal aspects of lung microarchitecture useful for diagnosis. Their most immediate relevance to current imaging practice is to cause rapid signal decays, commonly discussed in terms of short T 2 * values of 1 ms or lower at typical imaging field strengths. Herein we provide a brief review of previous studies describing and interpreting proton lung spectra. We then link these broad frequency distributions to rapid signal decays, though not necessarily the exponential decays generally used to define T 2 * values. We examine how these decays influence observed signal intensities and spatial mapping features associated with the most prominent torso imaging sequences, including spoiled gradient and spin echo sequences. Effects of imperfect refocusing pulses on the multiple echo signal decays in single shot fast spin echo (SSFSE) sequences and effects of broad frequency distributions on balanced steady state free precession (bSSFP) sequence signal intensities are also provided. The theoretical analyses are based on the concept of explicitly separating the effects of reversible and irreversible transverse relaxation processes, thus providing a somewhat novel and more general framework from which to estimate lung signal intensity behavior in modern imaging practice.

Lung Parenchymal Signal Intensity in MRI: A Technical Review with Educational Aspirations Regarding Reversible Versus Irreversible Transverse Relaxation Effects in Common Pulse Sequences

PubMed Central

MULKERN, ROBERT; HAKER, STEVEN; MAMATA, HATSUHO; LEE, EDWARD; MITSOURAS, DIMITRIOS; OSHIO, KOICHI; BALASUBRAMANIAN, MUKUND; HATABU, HIROTO

2014-01-01

Lung parenchyma is challenging to image with proton MRI. The large air space results in ~l/5th as many signal-generating protons compared to other organs. Air/tissue magnetic susceptibility differences lead to strong magnetic field gradients throughout the lungs and to broad frequency distributions, much broader than within other organs. Such distributions have been the subject of experimental and theoretical analyses which may reveal aspects of lung microarchitecture useful for diagnosis. Their most immediate relevance to current imaging practice is to cause rapid signal decays, commonly discussed in terms of short T2* values of 1 ms or lower at typical imaging field strengths. Herein we provide a brief review of previous studies describing and interpreting proton lung spectra. We then link these broad frequency distributions to rapid signal decays, though not necessarily the exponential decays generally used to define T2* values. We examine how these decays influence observed signal intensities and spatial mapping features associated with the most prominent torso imaging sequences, including spoiled gradient and spin echo sequences. Effects of imperfect refocusing pulses on the multiple echo signal decays in single shot fast spin echo (SSFSE) sequences and effects of broad frequency distributions on balanced steady state free precession (bSSFP) sequence signal intensities are also provided. The theoretical analyses are based on the concept of explicitly separating the effects of reversible and irreversible transverse relaxation processes, thus providing a somewhat novel and more general framework from which to estimate lung signal intensity behavior in modern imaging practice. PMID:25228852

The spatial distribution and temporal variation of desert riparian forests and their influencing factors in the downstream Heihe River basin, China

NASA Astrophysics Data System (ADS)

Ding, Jingyi; Zhao, Wenwu; Daryanto, Stefani; Wang, Lixin; Fan, Hao; Feng, Qiang; Wang, Yaping

2017-05-01

Desert riparian forests are the main restored vegetation community in Heihe River basin. They provide critical habitats and a variety of ecosystem services in this arid environment. Since desert riparian forests are also sensitive to disturbance, examining the spatial distribution and temporal variation of these forests and their influencing factors is important to determine the limiting factors of vegetation recovery after long-term restoration. In this study, field experiment and remote sensing data were used to determine the spatial distribution and temporal variation of desert riparian forests and their relationship with the environmental factors. We classified five types of vegetation communities at different distances from the river channel. Community coverage and diversity formed a bimodal pattern, peaking at the distances of 1000 and 3000 m from the river channel. In general, the temporal normalized difference vegetation index (NDVI) trend from 2000 to 2014 was positive at different distances from the river channel, except for the region closest to the river bank (i.e. within 500 m from the river channel), which had been undergoing degradation since 2011. The spatial distribution of desert riparian forests was mainly influenced by the spatial heterogeneity of soil properties (e.g. soil moisture, bulk density and soil particle composition). Meanwhile, while the temporal variation of vegetation was affected by both the spatial heterogeneity of soil properties (e.g. soil moisture and soil particle composition) and to a lesser extent, the temporal variation of water availability (e.g. annual average and variability of groundwater, soil moisture and runoff). Since surface (0-30 cm) and deep (100-200 cm) soil moisture, bulk density and the annual average of soil moisture at 100 cm obtained from the remote sensing data were regarded as major determining factors of community distribution and temporal variation, conservation measures that protect the soil structure and prevent soil moisture depletion (e.g. artificial soil cover and water conveyance channels) were suggested to better protect desert riparian forests under climate change and intensive human disturbance.

Spatial Interpolation of Historical Seasonal Rainfall Indices over Peninsular Malaysia

NASA Astrophysics Data System (ADS)

Hassan, Zulkarnain; Haidir, Ahmad; Saad, Farah Naemah Mohd; Ayob, Afizah; Rahim, Mustaqqim Abdul; Ghazaly, Zuhayr Md.

2018-03-01

The inconsistency in inter-seasonal rainfall due to climate change will cause a different pattern in the rainfall characteristics and distribution. Peninsular Malaysia is not an exception for this inconsistency, in which it is resulting extreme events such as flood and water scarcity. This study evaluates the seasonal patterns in rainfall indices such as total amount of rainfall, the frequency of wet days, rainfall intensity, extreme frequency, and extreme intensity in Peninsular Malaysia. 40 years (1975-2015) data records have been interpolated using Inverse Distance Weighted method. The results show that the formation of rainfall characteristics are significance during the Northeast monsoon (NEM), as compared to Southwest monsoon (SWM). Also, there is a high rainfall intensity and frequency related to extreme over eastern coasts of Peninsula during the NEM season.

Effects of Anisotropic Excitation in Laser-Induced Fluorescence Spectroscopy (LIFS)

NASA Astrophysics Data System (ADS)

Fujimoto, Takashi; Goto, Chiaki; Uetani, Yasunori; Fukuda, Kuniya

1985-07-01

Various features of the effect of alignment in the upper-level population on the observed emission-line intensity, i.e., the spatially-anisotropic intensity distribution and polarization, are demonstrated using laser-induced fluorescence spectroscopy on the neon 2p53s-2p53p transitions in a plasma. Disalignment by atomic collision is observed on the 2p2 level, and its rate coefficient is determined as (1.70± 0.03)× 10-10 cm3s-1. The case of hyperfine-structure lines is discussed. Polarization is observed in the hydrogen Balmer α line fluorescence following the laser excitation of the same transition. Conditions are given under which the alignment effect is eliminated or can be neglected. Cases of unpolarized-light excitation and high-intensity excitation are discussed.

Localization of rainfall and determination its intensity in the lower layers of the troposphere from the measurements of local RF transmitter characteristics

NASA Astrophysics Data System (ADS)

Podhorský, Dušan; Fabo, Peter

2016-12-01

The article deals with a method of acquiring the temporal and spatial distribution of local precipitation from measurement of performance characteristics of local sources of high frequency electromagnetic radiation in the 1-3GHz frequency range in the lower layers of the troposphere up to 100 m. The method was experimentally proven by monitoring the GSM G2 base stations of cell phone providers in the frequency range of 920-960MHz using methods of frequential and spatial diversity reception. Modification of the SART method for localization of precipitation was also proposed. The achieved results allow us to obtain the timeframe of the intensity of local precipitation in the observed area with a temporal resolution of 10 sec. A spatial accuracy of 100m in localization of precipitation is expected, after a network of receivers is built. The acquired data can be used as one of the inputs for meteorological forecasting models, in agriculture, hydrology as a supplementary method to ombrograph stations and measurements for the weather radar network, in transportation as part of a warning system and in many other areas.

Characterization of an Optical Device with an Array of Blue Light Emitting Diodes LEDS for Treatment of Neonatal Jaundice.

NASA Astrophysics Data System (ADS)

Sebbe, Priscilla Fróes; Villaverde, Antonio G. J. Balbin; Nicolau, Renata Amadei; Barbosa, Ana Maria; Veissid, Nelson

2008-04-01

Phototherapy is a treatment that consists in irradiating a patient with light of high intensity, which promotes beneficial photochemical transformations in the irradiated area. The phototherapy for neonates is applied to break down the bilirubin, an organic pigment that is a sub product of the erythrocytes degradation, and to increase its excretion by the organism. Neonates should be irradiated with light of wavelength that the bilirubin can absorb, and with spectral irradiances between 4 and 16 μW/cm2/nm. The efficiency of the treatment depends on the irradiance and the area of the body that is irradiated. A convenient source of light for treatment of neonatal jaundice is the blue Light Emitter Diode (LED), emitting in the range of 400 to 500 nm, with power of the order of 10-150 mW. Some of the advantages for using LEDS are: low cost, operating long lifetime (over 100,000 hours), narrow emission linewith, low voltage power supply requirement and low heating. The aim of this work was to build and characterize a device for phototherapy treatment of neonatal jaundice. This consists of a blanket with 88 blue LEDs (emission peak at 472 nm), arranged in an 8×11 matrix, all connected in parallel and powered by a 5V-2A power supply. The device was characterized by using a spectroradiometer USB2000 (Ocean Optics Inc, USA), with a sensitivity range of 339-1019 nm. For determination of light spatial uniformity was used a calibrated photovoltaic sensor for measuring light intensity and mapping of the light intensity spatial distribution. Results indicate that our device shows a uniform spatial distribution for distances from the blanket larger than 10 cm, with a maximum of irradiance at such a distance. This device presenting a large and uniform area of irradiation, efficient wavelength emission and high irradiance seems to be promising for neonates' phototherapy treatment.

Simulations of transient membrane behavior in cells subjected to a high-intensity ultrashort electric pulse.

PubMed

Hu, Q; Viswanadham, S; Joshi, R P; Schoenbach, K H; Beebe, S J; Blackmore, P F

2005-03-01

A molecular dynamics (MD) scheme is combined with a distributed circuit model for a self-consistent analysis of the transient membrane response for cells subjected to an ultrashort (nanosecond) high-intensity (approximately 0.01-V/nm spatially averaged field) voltage pulse. The dynamical, stochastic, many-body aspects are treated at the molecular level by resorting to a course-grained representation of the membrane lipid molecules. Coupling the Smoluchowski equation to the distributed electrical model for current flow provides the time-dependent transmembrane fields for the MD simulations. A good match between the simulation results and available experimental data is obtained. Predictions include pore formation times of about 5-6 ns. It is also shown that the pore formation process would tend to begin from the anodic side of an electrically stressed membrane. Furthermore, the present simulations demonstrate that ions could facilitate pore formation. This could be of practical importance and have direct relevance to the recent observations of calcium release from the endoplasmic reticulum in cells subjected to such ultrashort, high-intensity pulses.

On the relationship between acoustic energy density flux near the jet axis and far field acoustic intensity

NASA Technical Reports Server (NTRS)

Maestrello, L.

1973-01-01

By measurement and analysis, the relationship between the distribution of the outflow of acoustic energy over the jet boundary and the far-field intensity is considered. The physical quantity used is the gradient of the pressure evaluated on a geometrical plane at the smallest possible radial distance from the jet axis, but outside the vortical region, in the area where the homogeneous wave equation is reasonably well satisfied. The numerical and experimental procedures involved have been checked out by using a known source. Results indicate that the acoustic power output per unit length of the jet, in the region from which the sound emanates, peaks at approximately 9 diameters downstream. The acoustic emission for a jet Strouhal number of about 0.3 exceeds the emission for all other Strouhal numbers nearly everywhere along the measurement plane. However, the far-field peak intensity distribution obtained from the contribution of each station was found to depend on the spatial extent of the region where sound emanates from the jet, which, in turn, depends more on the far-field angle than on the Strouhal number.

Correlation of spatial intensity distribution of light reaching the retina and restoration of vision by optogenetic stimulation

NASA Astrophysics Data System (ADS)

Shivalingaiah, Shivaranjani; Gu, Ling; Mohanty, Samarendra K.

2011-03-01

Stimulation of retinal neuronal cells using optogenetics via use of chanelrhodopsin-2 (ChR2) and blue light has opened up a new direction for restoration of vision with respect to treatment of Retinitis pigmentosa (RP). In addition to delivery of ChR2 to specific retinal layer using genetic engineering, threshold level of blue light needs to be delivered onto the retina for generating action potential and successful behavioral outcome. We report measurement of intensity distribution of light reaching the retina of Retinitis pigmentosa (RP) mouse models and compared those results with theoretical simulations of light propagation in eye. The parameters for the stimulating source positioning in front of eye was determined for optimal light delivery to the retina. In contrast to earlier viral method based delivery of ChR2 onto retinal ganglion cells, in-vivo electroporation method was employed for retina-transfection of RP mice. The behavioral improvement in mice with Thy1-ChR2-YFP transfected retina, expressing ChR2 in retinal ganglion cells, was found to correlate with stimulation intensity.

A simple stochastic rainstorm generator for simulating spatially and temporally varying rainfall

NASA Astrophysics Data System (ADS)

Singer, M. B.; Michaelides, K.; Nichols, M.; Nearing, M. A.

2016-12-01

In semi-arid to arid drainage basins, rainstorms often control both water supply and flood risk to marginal communities of people. They also govern the availability of water to vegetation and other ecological communities, as well as spatial patterns of sediment, nutrient, and contaminant transport and deposition on local to basin scales. All of these landscape responses are sensitive to changes in climate that are projected to occur throughout western North America. Thus, it is important to improve characterization of rainstorms in a manner that enables statistical assessment of rainfall at spatial scales below that of existing gauging networks and the prediction of plausible manifestations of climate change. Here we present a simple, stochastic rainstorm generator that was created using data from a rich and dense network of rain gauges at the Walnut Gulch Experimental Watershed (WGEW) in SE Arizona, but which is applicable anywhere. We describe our methods for assembling pdfs of relevant rainstorm characteristics including total annual rainfall, storm area, storm center location, and storm duration. We also generate five fitted intensity-duration curves and apply a spatial rainfall gradient to generate precipitation at spatial scales below gauge spacing. The model then runs by Monte Carlo simulation in which a total annual rainfall is selected before we generate rainstorms until the annual precipitation total is reached. The procedure continues for decadal simulations. Thus, we keep track of the hydrologic impact of individual storms and the integral of precipitation over multiple decades. We first test the model using ensemble predictions until we reach statistical similarity to the input data from WGEW. We then employ the model to assess decadal precipitation under simulations of climate change in which we separately vary the distribution of total annual rainfall (trend in moisture) and the intensity-duration curves used for simulation (trends in storminess). We demonstrate the model output through spatial maps of rainfall and through statistical comparisons of relevant parameters and distributions. Finally, discuss how the model can be used to understand basin-scale hydrology in terms of soil moisture, runoff, and erosion.

Efficient Simulation of Tropical Cyclone Pathways with Stochastic Perturbations

NASA Astrophysics Data System (ADS)

Webber, R.; Plotkin, D. A.; Abbot, D. S.; Weare, J.

2017-12-01

Global Climate Models (GCMs) are known to statistically underpredict intense tropical cyclones (TCs) because they fail to capture the rapid intensification and high wind speeds characteristic of the most destructive TCs. Stochastic parametrization schemes have the potential to improve the accuracy of GCMs. However, current analysis of these schemes through direct sampling is limited by the computational expense of simulating a rare weather event at fine spatial gridding. The present work introduces a stochastically perturbed parametrization tendency (SPPT) scheme to increase simulated intensity of TCs. We adapt the Weighted Ensemble algorithm to simulate the distribution of TCs at a fraction of the computational effort required in direct sampling. We illustrate the efficiency of the SPPT scheme by comparing simulations at different spatial resolutions and stochastic parameter regimes. Stochastic parametrization and rare event sampling strategies have great potential to improve TC prediction and aid understanding of tropical cyclogenesis. Since rising sea surface temperatures are postulated to increase the intensity of TCs, these strategies can also improve predictions about climate change-related weather patterns. The rare event sampling strategies used in the current work are not only a novel tool for studying TCs, but they may also be applied to sampling any range of extreme weather events.

High-order nonuniformly correlated beams

NASA Astrophysics Data System (ADS)

Wu, Dan; Wang, Fei; Cai, Yangjian

2018-02-01

We have introduced a class of partially coherent beams with spatially varying correlations named high-order nonuniformly correlated (HNUC) beams, as an extension of conventional nonuniformly correlated (NUC) beams. Such beams bring a new parameter (mode order) which is used to tailor the spatial coherence properties. The behavior of the spectral density of the HNUC beams on propagation has been investigated through numerical examples with the help of discrete model decomposition and fast Fourier transform (FFT) algorithm. Our results reveal that by selecting the mode order appropriately, the more sharpened intensity maxima can be achieved at a certain propagation distance compared to that of the NUC beams, and the lateral shift of the intensity maxima on propagation is closed related to the mode order. Furthermore, analytical expressions for the r.m.s width and the propagation factor of the HNUC beams on free-space propagation are derived by means of Wigner distribution function. The influence of initial beam parameters on the evolution of the r.m.s width and the propagation factor, and the relation between the r.m.s width and the occurring of the sharpened intensity maxima on propagation have been studied and discussed in detail.

Longterm and spatial variability of Aerosol optical properties measured by sky radiometer in Japan sites

NASA Astrophysics Data System (ADS)

Aoki, K.

2016-12-01

Aerosols and cloud play an important role in the climate change. We started the long-term monitoring of aerosol and cloud optical properties since 1990's by using sky radiometer (POM-01, 02; Prede Co. Ltd., Japan). We provide the information, in this presentation, on the aerosol optical properties with respect to their temporal and spatial variability in Japan site (ex. Sapporo, Toyama, Kasuga and etc). The global distributions of aerosols have been derived from earth observation satellite and have been simulated in numerical models, which assume optical parameters. However, these distributions are difficult to derive because of variability in time and space. Therefore, Aerosol optical properties were investigated using the measurements from ground-based and ship-borne sky radiometer. The sky radiometer is an automatic instrument that takes observations only in daytime under the clear sky conditions. Observation of diffuse solar intensity interval was made every ten or five minutes by once. The aerosol optical properties were computed using the SKYRAD.pack version 4.2. The obtained Aerosol optical properties (Aerosol optical thickness, Ångström exponent, Single scattering albedo, and etc.) and size distribution volume clearly showed spatial and temporal variability in Japan area. In this study, we present the temporal and spatial variability of Aerosol optical properties at several Japan sites, applied to validation of satellite and numerical models. This project is validation satellite of GCOM-C, JAXA. The GCOM-C satellite scheduled to be launched in early 2017.

Distributed watershed modeling of design storms to identify nonpoint source loading areas

DOE Office of Scientific and Technical Information (OSTI.GOV)

Endreny, T.A.; Wood, E.F.

1999-03-01

Watershed areas that generate nonpoint source (NPS) polluted runoff need to be identified prior to the design of basin-wide water quality projects. Current watershed-scale NPS models lack a variable source area (VSA) hydrology routine, and are therefore unable to identify spatially dynamic runoff zones. The TOPLATS model used a watertable-driven VSA hydrology routine to identify runoff zones in a 17.5 km{sup 2} agricultural watershed in central Oklahoma. Runoff areas were identified in a static modeling framework as a function of prestorm watertable depth and also in a dynamic modeling framework by simulating basin response to 2, 10, and 25 yrmore » return period 6 h design storms. Variable source area expansion occurred throughout the duration of each 6 h storm and total runoff area increased with design storm intensity. Basin-average runoff rates of 1 mm h{sup {minus}1} provided little insight into runoff extremes while the spatially distributed analysis identified saturation excess zones with runoff rates equaling effective precipitation. The intersection of agricultural landcover areas with these saturation excess runoff zones targeted the priority potential NPS runoff zones that should be validated with field visits. These intersected areas, labeled as potential NPS runoff zones, were mapped within the watershed to demonstrate spatial analysis options available in TOPLATS for managing complex distributions of watershed runoff. TOPLATS concepts in spatial saturation excess runoff modelling should be incorporated into NPS management models.« less

Internal noise sources limiting contrast sensitivity.

PubMed

Silvestre, Daphné; Arleo, Angelo; Allard, Rémy

2018-02-07

Contrast sensitivity varies substantially as a function of spatial frequency and luminance intensity. The variation as a function of luminance intensity is well known and characterized by three laws that can be attributed to the impact of three internal noise sources: early spontaneous neural activity limiting contrast sensitivity at low luminance intensities (i.e. early noise responsible for the linear law), probabilistic photon absorption at intermediate luminance intensities (i.e. photon noise responsible for de Vries-Rose law) and late spontaneous neural activity at high luminance intensities (i.e. late noise responsible for Weber's law). The aim of this study was to characterize how the impact of these three internal noise sources vary with spatial frequency and determine which one is limiting contrast sensitivity as a function of luminance intensity and spatial frequency. To estimate the impact of the different internal noise sources, the current study used an external noise paradigm to factorize contrast sensitivity into equivalent input noise and calculation efficiency over a wide range of luminance intensities and spatial frequencies. The impact of early and late noise was found to drop linearly with spatial frequency, whereas the impact of photon noise rose with spatial frequency due to ocular factors.

Deforestation and rainfall recycling in Brazil: Is decreased forest cover connectivity associated with decreased rainfall connectivity?

NASA Astrophysics Data System (ADS)

Adera, S.; Larsen, L.; Levy, M. C.; Thompson, S. E.

2017-12-01

In the Brazilian rainforest-savanna transition zone, deforestation has the potential to significantly affect rainfall by disrupting rainfall recycling, the process by which regional evapotranspiration contributes to regional rainfall. Understanding rainfall recycling in this region is important not only for sustaining Amazon and Cerrado ecosystems, but also for cattle ranching, agriculture, hydropower generation, and drinking water management. Simulations in previous studies suggest complex, scale-dependent interactions between forest cover connectivity and rainfall. For example, the size and distribution of deforested patches has been found to affect rainfall quantity and spatial distribution. Here we take an empirical approach, using the spatial connectivity of rainfall as an indicator of rainfall recycling, to ask: as forest cover connectivity decreased from 1981 - 2015, how did the spatial connectivity of rainfall change in the Brazilian rainforest-savanna transition zone? We use satellite forest cover and rainfall data covering this period of intensive forest cover loss in the region (forest cover from the Hansen Global Forest Change dataset; rainfall from the Climate Hazards Infrared Precipitation with Stations dataset). Rainfall spatial connectivity is quantified using transfer entropy, a metric from information theory, and summarized using network statistics. Networks of connectivity are quantified for paired deforested and non-deforested regions before deforestation (1981-1995) and during/after deforestation (2001-2015). Analyses reveal a decline in spatial connectivity networks of rainfall following deforestation.

Characterization of fracture aperture for groundwater flow and transport

NASA Astrophysics Data System (ADS)

Sawada, A.; Sato, H.; Tetsu, K.; Sakamoto, K.

2007-12-01

This paper presents experiments and numerical analyses of flow and transport carried out on natural fractures and transparent replica of fractures. The purpose of this study was to improve the understanding of the role of heterogeneous aperture patterns on channelization of groundwater flow and dispersion in solute transport. The research proceeded as follows: First, a precision plane grinder was applied perpendicular to the fracture plane to characterize the aperture distribution on a natural fracture with 1 mm of increment size. Although both time and labor were intensive, this approach provided a detailed, three dimensional picture of the pattern of fracture aperture. This information was analyzed to provide quantitative measures for the fracture aperture distribution, including JRC (Joint Roughness Coefficient) and fracture contact area ratio. These parameters were used to develop numerical models with corresponding synthetic aperture patterns. The transparent fracture replica and numerical models were then used to study how transport is affected by the aperture spatial pattern. In the transparent replica, transmitted light intensity measured by a CCD camera was used to image channeling and dispersion due to the fracture aperture spatial pattern. The CCD image data was analyzed to obtain the quantitative fracture aperture and tracer concentration data according to Lambert-Beer's law. The experimental results were analyzed using the numerical models. Comparison of the numerical models to the transparent replica provided information about the nature of channeling and dispersion due to aperture spatial patterns. These results support to develop a methodology for defining representative fracture aperture of a simplified parallel fracture model for flow and transport in heterogeneous fractures for contaminant transport analysis.

Spatial distributing characteristics of land use in the southern slope of mid-Himalaya Mountains

NASA Astrophysics Data System (ADS)

Lu, Chen

2014-12-01

The southern slope of mid-Himalayan Mountains located in China's Qomolangma National Natural Reserve in Tibet Autonomous Region, is made up of several non-continuous valleys. The study collected the data including DEM(SRTM90m), 1/250,000 land use map(year 2000), 1/100 million vegetation types map ,satellite images of 4 typical valleys on Google Earth Planet Map. Made use of ArcGIS9.3 spatial analysis technology, analyzed into the 2 aspects— Mountain altitudinal belts and slope gradient of soil types of Qinghai-Tibet Plateau, so as to abtain the spatial distributing characteristics of farmland and grassland in the research areas. The conclusions indicates that: (1)no farmland below 2200m altitude, land use is influenced intensively by slope gradient factor in the altitude range of < 2500m; (2)it is in 2500m-3800m altitude range meanwhile on the 2 farming suitable slope gradient belts(<5°, 5-15°) that the very focus zone has got the relatively larger potential, suitability and yield of farming utilization; (3)on the 3 grazing suitable slope gradient belts(<5°,5-15°,15-35°), the respective fodder quantities of the 4 valleys has low differences. land use of the 4 valleys are intensively restricted by altitude and slope gradient factors so that cultivating and grazing activities take place widely on the farming unsuitable slope gradient belts(15-35°,>35°) and grazing unsuitable slope gradient belt(>35°), which is disadvantaged to ecological environmental protection and rational utilization of land resources.

Lévy noise improves the electrical activity in a neuron under electromagnetic radiation.

PubMed

Wu, Juan; Xu, Yong; Ma, Jun

2017-01-01

As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected.

Lévy noise improves the electrical activity in a neuron under electromagnetic radiation

PubMed Central

Wu, Juan; Ma, Jun

2017-01-01

As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected. PMID:28358824

Patterns of infestation by the trombiculid mite Eutrombicula alfreddugesi in four sympatric lizard species (genus Tropidurus) in northeastern Brazil.

PubMed

Rocha, C F D; Cunha-Barros, M; Menezes, V A; Fontes, A f; Vrcibradic, D; Van Sluys, M

2008-06-01

We studied the parasitism by the chigger mite Eutrombicula alfreddugesi on four sympatric lizard species of the genus Tropidurus in Morro do Chapéu, Bahia state, Brazil: T. hispidus, T. cocorobensis, T. semitaeniatus and T. erythrocephalus. For each species, we investigated the patterns of infestation and analyzed to which extent they varied among the hosts. We calculated the spatial niche breadth of the chigger mite on the body of each host species and the distribution of mites along the hosts' bodies for each Tropidurus species. All four species of Tropidurus at Morro do Chapéu were parasited by the chigger mite, with high (97-100%) prevalences. Host body size significantly explained the intensity of mite infestation for all species, except T. erythrocephalus. The body regions with highest intensity of infestation in the four lizard species were the mite pockets. The spacial niche width of the chigger varied consistently among the four lizards species studied being highest for T. erytrocephalus and lowest for T. cocorobensis. We conclude that the distribution and intensity with which lizards of the genus Tropidurus are infested by Eutrombicula alfreddugesi larvae results from the interaction between aspects of host morphology (such as body size and the occurrence and distribution of mite pockets) and ecology (especially microhabitat use).

The use of distributed hydrological models for the Gard 2002 flash flood event: Analysis of associated hydrological processes

NASA Astrophysics Data System (ADS)

Braud, Isabelle; Roux, Hélène; Anquetin, Sandrine; Maubourguet, Marie-Madeleine; Manus, Claire; Viallet, Pierre; Dartus, Denis

2010-11-01

SummaryThis paper presents a detailed analysis of the September 8-9, 2002 flash flood event in the Gard region (southern France) using two distributed hydrological models: CVN built within the LIQUID® hydrological platform and MARINE. The models differ in terms of spatial discretization, infiltration and water redistribution representation, and river flow transfer. MARINE can also account for subsurface lateral flow. Both models are set up using the same available information, namely a DEM and a pedology map. They are forced with high resolution radar rainfall data over a set of 18 sub-catchments ranging from 2.5 to 99 km2 and are run without calibration. To begin with, models simulations are assessed against post field estimates of the time of peak and the maximum peak discharge showing a fair agreement for both models. The results are then discussed in terms of flow dynamics, runoff coefficients and soil saturation dynamics. The contribution of the subsurface lateral flow is also quantified using the MARINE model. This analysis highlights that rainfall remains the first controlling factor of flash flood dynamics. High rainfall peak intensities are very influential of the maximum peak discharge for both models, but especially for the CVN model which has a simplified overland flow transfer. The river bed roughness also influences the peak intensity and time. Soil spatial representation is shown to have a significant role on runoff coefficients and on the spatial variability of saturation dynamics. Simulated soil saturation is found to be strongly related with soil depth and initial storage deficit maps, due to a full saturation of most of the area at the end of the event. When activated, the signature of subsurface lateral flow is also visible in the spatial patterns of soil saturation with higher values concentrating along the river network. However, the data currently available do not allow the assessment of both patterns. The paper concludes with a set of recommendations for enhancing field observations in order to progress in process understanding and gather a larger set of data to improve the realism of distributed models.

Spatially and temporally resolved measurements of a dense copper plasma heated by intense relativistic electrons

NASA Astrophysics Data System (ADS)

Coleman, J. E.; Colgan, J.

2017-08-01

A 100-μm-thick Cu foil is isochorically heated by a ˜100-ns-long electron bunch with an energy of 19.8 MeV and current of 1.7 kA to Te > 1 eV. After 100 ns of heating and 20 ns of expansion, the plasma exhibits a stable, quiescent temperature and density distribution for >200 ns. Several intense Cu-I emission lines are observed after ˜20 J of electron beam energy is deposited. These lines have well known Stark widths providing a direct measurement of ne. The Los Alamos ATOMIC code [Magee et al., AIP Conf. Proc. 2004, 168-179 and Hakel et al., J. Quant. Spectrosc. Radiat. Transfer 99, 265 (2006)] was run in local-thermodynamic-equilibrium mode to estimate Te and ne. Spatially and temporally resolved measurements are presented in both the vertical and horizontal directions adjacent to the foil indicating temperatures >1 eV and densities ranging from 1-3 × 1017 cm-3 after expansion and cooling.

Infrared observations of Jovian aurora from Juno's first orbits: Main oval and satellite footprints

NASA Astrophysics Data System (ADS)

Mura, A.; Adriani, A.; Altieri, F.; Connerney, J. E. P.; Bolton, S. J.; Moriconi, M. L.; Gérard, J.-C.; Kurth, W. S.; Dinelli, B. M.; Fabiano, F.; Tosi, F.; Atreya, S. K.; Bagenal, F.; Gladstone, G. R.; Hansen, C.; Levin, S. M.; Mauk, B. H.; McComas, D. J.; Sindoni, G.; Filacchione, G.; Migliorini, A.; Grassi, D.; Piccioni, G.; Noschese, R.; Cicchetti, A.; Turrini, D.; Stefani, S.; Amoroso, M.; Olivieri, A.

2017-06-01

The Jovian Infrared Auroral Mapper (JIRAM) is an imager/spectrometer on board NASA/Juno mission for the study of the Jovian aurorae. The first results of JIRAM's imager channel observations of the H3+ infrared emission, collected around the first Juno perijove, provide excellent spatial and temporal distribution of the Jovian aurorae, and show the morphology of the main ovals, the polar regions, and the footprints of Io, Europa and Ganymede. The extended Io "tail" persists for 3 h after the passage of the satellite flux tube. Multi-arc structures of varied spatial extent appear in both main auroral ovals. Inside the main ovals, intense, localized emissions are observed. In the southern aurora, an evident circular region of strong depletion of H3+ emissions is partially surrounded by an intense emission arc. The southern aurora is brighter than the north one in these observations. Similar, probably conjugate emission patterns are distinguishable in both polar regions.

Optical properties of m-plane GaN grown on patterned Si(112) substrates by MOCVD using a two-step approach

NASA Astrophysics Data System (ADS)

Izyumskaya, N.; Okur, S.; Zhang, F.; Monavarian, M.; Avrutin, V.; Özgür, Ü.; Metzner, S.; Karbaum, C.; Bertram, F.; Christen, J.; Morkoç, H.

2014-03-01

Nonpolar m-plane GaN layers were grown on patterned Si (112) substrates by metal-organic chemical vapor deposition (MOCVD). A two-step growth procedure involving a low-pressure (30 Torr) first step to ensure formation of the m-plane facet and a high-pressure step (200 Torr) for improvement of optical quality was employed. The layers grown in two steps show improvement of the optical quality: the near-bandedge photoluminescence (PL) intensity is about 3 times higher than that for the layers grown at low pressure, and deep emission is considerably weaker. However, emission intensity from m-GaN is still lower than that of polar and semipolar (1 100 ) reference samples grown under the same conditions. To shed light on this problem, spatial distribution of optical emission over the c+ and c- wings of the nonpolar GaN/Si was studied by spatially resolved cathodoluminescence and near-field scanning optical microscopy.

Statistical Maps of Ground Magnetic Disturbance Derived from Global Geospace Models

NASA Astrophysics Data System (ADS)

Rigler, E. J.; Wiltberger, M. J.; Love, J. J.

2017-12-01

Electric currents in space are the principal driver of magnetic variations measured at Earth's surface. These in turn induce geoelectric fields that present a natural hazard for technological systems like high-voltage power distribution networks. Modern global geospace models can reasonably simulate large-scale geomagnetic response to solar wind variations, but they are less successful at deterministic predictions of intense localized geomagnetic activity that most impacts technological systems on the ground. Still, recent studies have shown that these models can accurately reproduce the spatial statistical distributions of geomagnetic activity, suggesting that their physics are largely correct. Since the magnetosphere is a largely externally driven system, most model-measurement discrepancies probably arise from uncertain boundary conditions. So, with realistic distributions of solar wind parameters to establish its boundary conditions, we use the Lyon-Fedder-Mobarry (LFM) geospace model to build a synthetic multivariate statistical model of gridded ground magnetic disturbance. From this, we analyze the spatial modes of geomagnetic response, regress on available measurements to fill in unsampled locations on the grid, and estimate the global probability distribution of extreme magnetic disturbance. The latter offers a prototype geomagnetic "hazard map", similar to those used to characterize better-known geophysical hazards like earthquakes and floods.

Recent warming leads to a rapid borealization of fish communities in the Arctic

NASA Astrophysics Data System (ADS)

Fossheim, Maria; Primicerio, Raul; Johannesen, Edda; Ingvaldsen, Randi B.; Aschan, Michaela M.; Dolgov, Andrey V.

2015-07-01

Arctic marine ecosystems are warming twice as fast as the global average. As a consequence of warming, many incoming species experience increasing abundances and expanding distribution ranges in the Arctic. The Arctic is expected to have the largest species turnover with regard to invading and locally extinct species, with a modelled invasion intensity of five times the global average. Studies in this region might therefore give valuable insights into community-wide shifts of species driven by climate warming. We found that the recent warming in the Barents Sea has led to a change in spatial distribution of fish communities, with boreal communities expanding northwards at a pace reflecting the local climate velocities. Increased abundance and distribution areas of large, migratory fish predators explain the observed community-wide distributional shifts. These shifts change the ecological interactions experienced by Arctic fish species. The Arctic shelf fish community retracted northwards to deeper areas bordering the deep polar basin. Depth might limit further retraction of some of the fish species in the Arctic shelf community. We conclude that climate warming is inducing structural change over large spatial scales at high latitudes, leading to a borealization of fish communities in the Arctic.

Modulation of chorus intensity by ULF waves deep in the inner magnetosphere

DOE PAGES

Xia, Zhiyang; Chen, Lunjin; Dai, Lei; ...

2016-09-05

Previous studies have shown that chorus wave intensity can be modulated by Pc4-Pc5 compressional ULF waves. In this paper, we present Van Allen Probes observation of ULF wave modulating chorus wave intensity, which occurred deep in the magnetosphere. The ULF wave shows fundamental poloidal mode signature and mirror mode compressional nature. The observed ULF wave can modulate not only the chorus wave intensity but also the distribution of both protons and electrons. Linear growth rate analysis shows consistence with observed chorus intensity variation at low frequency (f <~ 0.3f ce), but cannot account for the observed higher-frequency chorus waves, includingmore » the upper band chorus waves. This suggests the chorus waves at higher-frequency ranges require nonlinear mechanisms. Finally, in addition, we use combined observations of Radiation Belt Storm Probes (RBSP) A and B to verify that the ULF wave event is spatially local and does not last long.« less

Estimation of marine mineral resources abundance using back-scattering intensity of Deep-tow Side Scan Sonar

NASA Astrophysics Data System (ADS)

Yoo, C. M.; Joo, J.; Hyeong, K.; Chi, S. B.

2016-12-01

Manganese nodule, also known as polymetallic nodule, contains precious elements in high contents and is regarded as one of the most important future mineral resources. It occurs throughout the world oceans, but economically feasible deposits show limited distribution only in several deepsea basins including Clarion-Clipperton Fracture Zone (CCFZ) in northeast equatorial Pacific. Estimation of resources potential is one of the key factors prerequisite for economic feasibility study. Nodule abundance is commonly estimated from direct nodule sampling, however it is difficult to obtain statistically robust data because of highly variable spatial distribution and high cost of direct sampling. Variogram analysis indicates 3.5×3.5km sampling resolution to obtain indicated category of resources data, which requires over 1,000 sampling operations to cover the potential exploitation area with mining life of 20-30 years. High-resolution acoustic survey, bathymetry and back-scattered intensity, can provide high-resolution resources data with the definition of obstacles, such as faults and scarps, for operation of nodule collecting robots. We operated 120 kHz deep-tow side scan sonar (DTSSS) with spatial resolution of 1×1m in a representative area. Sea floor images were also taken continuously by deep-tow camera from selected tracks, converted to nodule abundance using image analysis program and conversion equation, and compared with acoustic data. Back-scattering intensity values could be divided into several group and translated into nodule abundance with high confidence level. Our result indicates that high resolution acoustic survey is appropriate tool for reliable assessment of manganese nodule abundance and definition of minable area.

Modulation of the pupil function of microscope objective lens for multifocal multi-photon microscopy using a spatial light modulator

NASA Astrophysics Data System (ADS)

Matsumoto, Naoya; Okazaki, Shigetoshi; Takamoto, Hisayoshi; Inoue, Takashi; Terakawa, Susumu

2014-02-01

We propose a method for high precision modulation of the pupil function of a microscope objective lens to improve the performance of multifocal multi-photon microscopy (MMM). To modulate the pupil function, we adopt a spatial light modulator (SLM) and place it at the conjugate position of the objective lens. The SLM can generate an arbitrary number of spots to excite the multiple fluorescence spots (MFS) at the desired positions and intensities by applying an appropriate computer-generated hologram (CGH). This flexibility allows us to control the MFS according to the photobleaching level of a fluorescent protein and phototoxicity of a specimen. However, when a large number of excitation spots are generated, the intensity distribution of the MFS is significantly different from the one originally designed due to misalignment of the optical setup and characteristics of the SLM. As a result, the image of a specimen obtained using laser scanning for the MFS has block noise segments because the SLM could not generate a uniform MFS. To improve the intensity distribution of the MFS, we adaptively redesigned the CGH based on the observed MFS. We experimentally demonstrate an improvement in the uniformity of a 10 × 10 MFS grid using a dye solution. The simplicity of the proposed method will allow it to be applied for calibration of MMM before observing living tissue. After the MMM calibration, we performed laser scanning with two-photon excitation to observe a real specimen without detecting block noise segments.

Simulation of future groundwater recharge using a climate model ensemble and SAR-image based soil parameter distributions - A case study in an intensively-used Mediterranean catchment.

PubMed

Herrmann, Frank; Baghdadi, Nicolas; Blaschek, Michael; Deidda, Roberto; Duttmann, Rainer; La Jeunesse, Isabelle; Sellami, Haykel; Vereecken, Harry; Wendland, Frank

2016-02-01

We used observed climate data, an ensemble of four GCM-RCM combinations (global and regional climate models) and the water balance model mGROWA to estimate present and future groundwater recharge for the intensively-used Thau lagoon catchment in southern France. In addition to a highly resolved soil map, soil moisture distributions obtained from SAR-images (Synthetic Aperture Radar) were used to derive the spatial distribution of soil parameters covering the full simulation domain. Doing so helped us to assess the impact of different soil parameter sources on the modelled groundwater recharge levels. Groundwater recharge was simulated in monthly time steps using the ensemble approach and analysed in its spatial and temporal variability. The soil parameters originating from both sources led to very similar groundwater recharge rates, proving that soil parameters derived from SAR images may replace traditionally used soil maps in regions where soil maps are sparse or missing. Additionally, we showed that the variance in different GCM-RCMs influences the projected magnitude of future groundwater recharge change significantly more than the variance in the soil parameter distributions derived from the two different sources. For the period between 1950 and 2100, climate change impacts based on the climate model ensemble indicated that overall groundwater recharge will possibly show a low to moderate decrease in the Thau catchment. However, as no clear trend resulted from the ensemble simulations, reliable recommendations for adapting the regional groundwater management to changed available groundwater volumes could not be derived. Copyright © 2015 Elsevier B.V. All rights reserved.

Into the environment of mosquito-borne disease: A spatial analysis of vector distribution using traditional and remotely sensed methods

NASA Astrophysics Data System (ADS)

Brown, Heidi E.

Spatially explicit information is increasingly available for infectious disease modeling. However, such information is reluctantly or inappropriately incorporated. My dissertation research uses spatially explicit data to assess relationships between landscape and mosquito species distribution and discusses challenges regarding accurate predictive risk modeling. The goal of my research is to use remotely sensed environmental information and spatial statistical methods to better understand mosquito-borne disease epidemiology for improvement of public health responses. In addition to reviewing the progress of spatial infectious disease modeling, I present four research projects. I begin by evaluating the biases in surveillance data and build up to predictive modeling of mosquito species presence. In the first study I explore how mosquito surveillance trap types influence estimations of mosquito populations. Then. I use county-based human surveillance data and landscape variables to identify risk factors for West Nile virus disease. The third study uses satellite-based vegetation indices to identify spatial variation among West Nile virus vectors in an urban area and relates the variability to virus transmission dynamics. Finally, I explore how information from three satellite sensors of differing spatial and spectral resolution can be used to identify and distinguish mosquito habitat across central Connecticut wetlands. Analyses presented here constitute improvements to the prediction of mosquito distribution and therefore identification of disease risk factors. Current methods for mosquito surveillance data collection are labor intensive and provide an extremely limited, incomplete picture of the species composition and abundance. Human surveillance data offers additional challenges with respect to reporting bias and resolution, but is nonetheless informative in identifying environmental risk factors and disease transmission dynamics. Remotely sensed imagery supports mosquito and human disease surveillance data by providing spatially explicit, line resolution information about environmental factors relevant to vector-borne disease processes. Together, surveillance and remotely sensed environmental data facilitate improved description and modeling of disease transmission. Remote sensing can be used to develop predictive maps of mosquito distribution in relation to disease risk. This has implications for increased accuracy of mosquito control efforts. The projects presented in this dissertation enhance current public health capacities by examining the applications of spatial modeling with respect to mosquito-borne disease.

Spatial regression between soil surface elevation, water storage in root zone and biomass productivity of alfalfa within an irrigated field

NASA Astrophysics Data System (ADS)

Zeyliger, Anatoly; Ermolaeva, Olga

2014-05-01

Efficiency of water use for the irrigation purposes is connected to the variety of circumstances, factors and processes appearing along the transportation path of water from its sources to the root zone of the plant. Water efficiency of agricultural irrigation is connected with variety of circumstances, the impacts and the processes occurring during the transportation of water from water sources to plant root zone. Agrohydrological processes occur directly at the irrigated field, these processes linked to the infiltration of the applied water subsequent redistribution of the infiltrated water within the root zone. One of them are agrohydrological processes occurring directly on an irrigated field, connected with infiltration of water applied for irrigation to the soil, and the subsequent redistribution of infiltrated water in the root zone. These processes have the strongly pronounced spatial character depending on the one hand from a spatial variation of some hydrological characteristics of soils, and from other hand with distribution of volume of irrigation water on a surface of the area of an irrigated field closely linked with irrigation technology used. The combination of water application parameters with agrohydrological characteristics of soils and agricultural vegetation in each point at the surface of an irrigated field leads to formation of a vector field of intensity of irrigation water. In an ideal situation, such velocity field on a soil surface should represent uniform set of vertically directed collinear vectors. Thus values of these vectors should be equal to infiltration intensities of water inflows on a soil surface. In soil profile the field of formed intensities of a water flow should lead to formation in it of a water storage accessible to root system of irrigated crops. In practice this ideal scheme undergoes a lot of changes. These changes have the different nature, the reasons of occurrence and degree of influence on the processes connected with formation of water flow and water storage. The major changes are formed as a result of imposing of the intensity fields on a soil surface and its field capillary infiltration rate. Excess of the first intensity over the second in each point of soil surface leads to formation of a layer of intensity of water not infiltrated in soil. Thus generate the new field of vectors of intensity which can consist of vertically directed vector of speed of evaporation, a quasi horizontal vector of intensity of a surface water flow and quasi vertical vector of intensity of a preferential flow directed downwards. Principal cause of excess of irrigation water application intensity over capillary infiltration rate can be on the one hand spatial non-uniformity of irrigation water application, and with other spatial variability of capillary infiltration rate, connected with spatial variability of water storage in the top layers of soil. As a result the spatial redistribution of irrigation water over irrigated filed forms distortions of ideal model of irrigation water storage in root zone of soil profile. The major differences consist in increasing of water storage in the depressions of a relief of an irrigated field and accordingly in their reduction on elevated zones of a relief, as well as losses of irrigation water outside of boundaries of a root zone of an irrigated field, in vertical, and horizontal directions. One of key parameters characterizing interaction between irrigation technology and soil state an irrigated field are intensity of water application, intensity and volume of a capillary infiltration, the water storage in root zone at the moment of infiltration starting and a topography of an irrigated field. Fnalyzing of spatial links between these characteristics a special research had been carried out on irrigated by sprinkler machine called Fregate at alfalfa field during the summer of 2012. This research carried out at experimental farm of the research institute VolgNIIGiM situated at a left bank of Volga River of Saratov Region of Russia (N51.384650°, E46.055890°). The digital elevation model of soil surface has been created, as well as monitoring of spatial water storage with EM 38 device and of a biomass were carried out. Layers of corresponding spatial data have been created and analyzed. The carried out analysis of spatial regresses has shown presence of links between productivity of a biomass of a alfalfa, water storage and topography. The obtained results shows the significance to include spatial characteristics of the topography and water storage to the irrigation models, as well as adaptation of sprinkler technology to allow differentiate the volume and rate of the applied water within the field. Special attention should be done to quantify relationships between uniform technology of water application by sprinkler and spatial nonuniformity of moisture storage (zoning of high soil moisture in depressions) in soil and as consequence of infiltration capacity.

Variability in rainfall at monitoring stations and derivation of a long-term rainfall intensity record in the Grand Canyon Region, Arizona, USA

USGS Publications Warehouse

Caster, Joshua J.; Sankey, Joel B.

2016-04-11

In this study, we examine rainfall datasets of varying temporal length, resolution, and spatial distribution to characterize rainfall depth, intensity, and seasonality for monitoring stations along the Colorado River within Marble and Grand Canyons. We identify maximum separation distances between stations at which rainfall measurements might be most useful for inferring rainfall characteristics at other locations. We demonstrate a method for applying relations between daily rainfall depth and intensity, from short-term high-resolution data to lower-resolution longer-term data, to synthesize a long-term record of daily rainfall intensity from 1950–2012. We consider the implications of our spatio-temporal characterization of rainfall for understanding local landscape change in sedimentary deposits and archaeological sites, and for better characterizing past and present rainfall and its potential role in overland flow erosion within the canyons. We find that rainfall measured at stations within the river corridor is spatially correlated at separation distances of tens of kilometers, and is not correlated at the large elevation differences that separate stations along the Colorado River from stations above the canyon rim. These results provide guidance for reasonable separation distances at which rainfall measurements at stations within the Grand Canyon region might be used to infer rainfall at other nearby locations along the river. Like other rugged landscapes, spatial variability between rainfall measured at monitoring stations appears to be influenced by canyon and rim physiography and elevation, with preliminary results suggesting the highest elevation landform in the region, the Kaibab Plateau, may function as an important orographic influence. Stations at specific locations within the canyons and along the river, such as in southern (lower) Marble Canyon and eastern (upper) Grand Canyon, appear to have strong potential to receive high-intensity rainfall that can generate runoff which may erode alluvium. The characterization of past and present rainfall variability in this study will be useful for future studies that evaluate more spatially continuous datasets in order to better understand the rainfall dynamics within this, and potentially other, deep canyons.

Spatial analysis for the identification of risk areas for schistosomiasis mansoni in the State of Sergipe, Brazil, 2005-2014.

PubMed

Santos, Allan Dantas Dos; Lima, Ana Caroline Rodrigues; Santos, Márcio Bezerra; Alves, José Antônio Barreto; Góes, Marco Aurélio de Oliveira; Nunes, Marco Antônio Prado; Sá, Sidney Lourdes César Souza; Araújo, Karina Conceição Gomes Machado de

2016-01-01

Schistosomiasis is a parasitic infectious disease with a worldwide prevalence. The objective of this work is to identify risk areas for schistosomiasis mansoni transmission in the State of Sergipe, Brazil, during the period from 2005 to 2014. We conducted an epidemiological study with secondary data from the Information System Control Program of Schistosomiasis [Sistema de Informação do Programa de Controle da Esquistossomose (SISPCE)]. Temporal trends were analyzed to obtain the annual percentage change (APC) in the rates of annual prevalence. In addition to the description of general indicators of the disease, the spatial analysis was descriptive, by means of the estimator of intensity kernel, and showed spatial dependence by indicators of global Moran (I) and Local Index of Spatial Association (LISA). Thematic maps of spatial distribution were made, identifying priority intervention areas in need of healthcare. There were 78,663 cases of schistosomiasis, with an average of 8.7% positivity recorded; 79.8% of the cases were treated, and Sergipe showed a decreasing positive trend (APC: -2.78). There was the presence of spatial autocorrelation and a significant global Moran index (I = 0.19; p-value = 0.03). We identified clusters of high-risk areas, mainly located in the northeast and southcentral of the state, which each had equally high infection rates. There was a decreasing positive trend of schistosomiasis in Sergipe. Spatial analysis identified the geographic distribution of risk and allowed the definition of priority areas for the maintenance and intensification of control interventions.

Volume moiré tomography based on projection extraction by spatial phase shifting of double crossed gratings

NASA Astrophysics Data System (ADS)

Wang, Jia; Guo, Zhenyan; Song, Yang; Han, Jun

2018-01-01

To realize volume moiré tomography (VMT) for the real three-dimensional (3D) diagnosis of combustion fields, according to 3D filtered back projection (FBP) reconstruction algorithm, the radial derivatives of the projected phase should be measured firstly. In this paper, a simple spatial phase-shifting moiré deflectometry with double cross gratings is presented to measure the radial first-order derivative of the projected phase. Based on scalar diffraction theory, the explicit analytical intensity distributions of moiré patterns on different diffracted orders are derived, and the spatial shifting characteristics are analyzed. The results indicate that the first-order derivatives of the projected phase in two mutually perpendicular directions are involved in moiré patterns, which can be combined to compute the radial first-order derivative. And multiple spatial phase-shifted moiré patterns can be simultaneously obtained; the phase-shifted values are determined by the parameters of the system. A four-step phase-shifting algorithm is proposed for phase extraction, and its accuracy is proved by numerical simulations. Finally, the moiré deflectometry is used to measure the radial first-order derivative of projected phase of a propane flame with plane incident wave, and the 3D temperature distribution is reconstructed.

Visualization of spatial patterns and temporal trends for aerial surveillance of illegal oil discharges in western Canadian marine waters.

PubMed

Serra-Sogas, Norma; O'Hara, Patrick D; Canessa, Rosaline; Keller, Peter; Pelot, Ronald

2008-05-01

This paper examines the use of exploratory spatial analysis for identifying hotspots of shipping-based oil pollution in the Pacific Region of Canada's Exclusive Economic Zone. It makes use of data collected from fiscal years 1997/1998 to 2005/2006 by the National Aerial Surveillance Program, the primary tool for monitoring and enforcing the provisions imposed by MARPOL 73/78. First, we present oil spill data as points in a "dot map" relative to coastlines, harbors and the aerial surveillance distribution. Then, we explore the intensity of oil spill events using the Quadrat Count method, and the Kernel Density Estimation methods with both fixed and adaptive bandwidths. We found that oil spill hotspots where more clearly defined using Kernel Density Estimation with an adaptive bandwidth, probably because of the "clustered" distribution of oil spill occurrences. Finally, we discuss the importance of standardizing oil spill data by controlling for surveillance effort to provide a better understanding of the distribution of illegal oil spills, and how these results can ultimately benefit a monitoring program.

Aggregating land use quantity and intensity to link water quality in upper catchment of Miyun Reservoir

NASA Astrophysics Data System (ADS)

Xu, E.

2015-12-01

Land use is closely related to hydrological and biochemical processes influencing the water quality. Quantifying relationship between both of them can help effectively manage land use to improve water quality. Previous studies majorly utilized land use quantity as an indicator to link water quality parameters, which lacked an insight to the influence of land use intensity. Taking upper catchment of Miyun Reservoir as a case study, we proposed a method of aggregating land use quantity and intensity to build a new land use indicator and investigated its explanation empower on water quality. Six nutrient concentrations from 52 sub-watersheds covering the whole catchment were used to characterize spatial distributions of water eutrophication. Based on spatial techniques and empirical conversion coefficients, combined remote sensing with socio-economic statistical data, land use intensity was measured and mapped visually. Then the new land use indicator was calculated and linked to nutrient concentrations by Pearson correlation coefficients. Results demonstrated that our new land use indicator incorporating intensity information can quantify the potential different nutrients exporting abilities from land uses. Comparing to traditional indicators only characterized by land use quantity, most Pearson correlation coefficients between new indicator and water nutrient concentrations increased. New information enhanced the explanatory power of land use on water nutrient concentrations. Then it can help better understand the impact of land use on water quality and guide land use management for supporting decision making.

Changes in the Intensity and Frequency of Atmospheric Blocking and Associated Heat Waves During Northern Summer Over Eurasia in the CMIP5 Model Simulations

NASA Technical Reports Server (NTRS)

Kim, Kyu-Myong; Lau, K. M.; Wu, H. T.; Kim, Maeng-Ki; Cho, Chunho

2012-01-01

The Russia heat wave and wild fires of the summer of 2010 was the most extreme weather event in the history of the country. Studies show that the root cause of the 2010 Russia heat wave/wild fires was an atmospheric blocking event which started to develop at the end of June and peaked around late July and early August. Atmospheric blocking in the summer of 2010 was anomalous in terms of the size, duration, and the location, which shifted to the east from the normal location. This and other similar continental scale severe summertime heat waves and blocking events in recent years have raised the question of whether such events are occurring more frequently and with higher intensity in a warmer climate induced by greenhouse gases. We studied the spatial and temporal distributions of the occurrence and intensity of atmospheric blocking and associated heat waves for northern summer over Eurasia based on CMIPS model simulations. To examine the global warming induced change of atmospheric blocking and heat waves, experiments for a high emissions scenario (RCP8.S) and a medium mitigation scenario (RCP4.S) are compared to the 20th century simulations (historical). Most models simulate the mean distributions of blockings reasonably well, including major blocking centers over Eurasia, northern Pacific, and northern Atlantic. However, the models tend to underestimate the number of blockings compared to MERRA and NCEPIDOE reanalysis, especially in western Siberia. Models also reproduced associated heat waves in terms of the shifting in the probability distribution function of near surface temperature. Seven out of eight models used in this study show that the frequency of atmospheric blocking over the Europe will likely decrease in a warmer climate, but slightly increase over the western Siberia. This spatial pattern resembles the blocking in the summer of 2010, indicating the possibility of more frequent occurrences of heat waves in western Siberia. In this talk, we will also discuss the potential effect of atmosphere-land feedback, particularly how the wetter spring affects the frequency and intensity of atmospheric blocking and heat wave during summer.

[Study on the risk assessment method of regional groundwater pollution].

PubMed

Yang, Yan; Yu, Yun-Jiang; Wang, Zong-Qing; Li, Ding-Long; Sun, Hong-Wei

2013-02-01

Based on the boundary elements of system risk assessment, the regional groundwater pollution risk assessment index system was preliminarily established, which included: regional groundwater specific vulnerability assessment, the regional pollution sources characteristics assessment and the health risk assessment of regional featured pollutants. The three sub-evaluation systems were coupled with the multi-index comprehensive method, the risk was characterized with the Spatial Analysis of ArcMap, and a new method to evaluate regional groundwater pollution risk that suitable for different parts of natural conditions, different types of pollution was established. Take Changzhou as an example, the risk of shallow groundwater pollution was studied with the new method, and found that the vulnerability index of groundwater in Changzhou is high and distributes unevenly; The distribution of pollution sources is concentrated and has a great impact on groundwater pollution risks; Influenced by the pollutants and pollution sources, the values of health risks are high in the urban area of Changzhou. The pollution risk of shallow groundwater is high and distributes unevenly, and distributes in the north of the line of Anjia-Xuejia-Zhenglu, the center of the city and the southeast, where the human activities are more intense and the pollution sources are intensive.

High resolution imaging of intracellular oxygen concentration by phosphorescence lifetime

PubMed Central

Kurokawa, Hiromi; Ito, Hidehiro; Inoue, Mai; Tabata, Kenji; Sato, Yoshifumi; Yamagata, Kazuya; Kizaka-Kondoh, Shinae; Kadonosono, Tetsuya; Yano, Shigenobu; Inoue, Masahiro; Kamachi, Toshiaki

2015-01-01

Optical methods using phosphorescence quenching by oxygen are suitable for sequential monitoring and non-invasive measurements for oxygen concentration (OC) imaging within cells. Phosphorescence intensity measurement is widely used with phosphorescent dyes. These dyes are ubiquitously but heterogeneously distributed inside the whole cell. The distribution of phosphorescent dye is a major disadvantage in phosphorescence intensity measurement. We established OC imaging system for a single cell using phosphorescence lifetime and a laser scanning confocal microscope. This system had improved spatial resolution and reduced the measurement time with the high repetition rate of the laser. By the combination of ubiquitously distributed phosphorescent dye with this lifetime imaging microscope, we can visualize the OC inside the whole cell and spheroid. This system uses reversible phosphorescence quenching by oxygen, so it can measure successive OC changes from normoxia to anoxia. Lower regions of OC inside the cell colocalized with mitochondria. The time-dependent OC change in an insulin-producing cell line MIN6 by the glucose stimulation was successfully visualized. Assessing the detailed distribution and dynamics of OC inside cells achieved by the presented system will be useful to understanding a physiological and pathological oxygen metabolism. PMID:26065366

Ten Years of Gamma-Ray Bursts Observations with BATSE

NASA Technical Reports Server (NTRS)

Fishman, Gerald J.; Rose, M. Franklin (Technical Monitor)

2000-01-01

The observed gamma-ray temporal, spectral, intensity and spatial distribution characteristics of GRBs from data obtained from BATSE/Compton Observatory, will be described. The talk will concentrate on recent studies of burst properties, correlations of GRB parameters and other statistical studies that have only recently come to light with the unprecedented sample of over 2700 GRBS. Recent studies of possible observational biases, un-triggered GRBs and threshold calculations for BATSE will also be described.

Joint Discussion/Mini-Workshop: Gamma-Ray Bursts and their Hosts

NASA Technical Reports Server (NTRS)

Fishman, Gerald J.

2000-01-01

The observed gamma-ray temporal, spectral, intensity and spatial distribution characteristics of GRBs, primarily from data obtained from the Compton Observatory, will be described. The talk will concentrate on recent studies of burst properties, correlations of GRB parameters and other statistical studies that have only recently come to light with the unprecedented sample of over two thousand GRBs, along with some mention of studies in progress by members of the BATSE team.

Mapping snow depth distribution in forested terrain using unmanned aerial vehicles and structure-from-motion

NASA Astrophysics Data System (ADS)

Webster, C.; Bühler, Y.; Schirmer, M.; Stoffel, A.; Giulia, M.; Jonas, T.

2017-12-01

Snow depth distribution in forests exhibits strong spatial heterogeneity compared to adjacent open sites. Measurement of snow depths in forests is currently limited to a) manual point measurements, which are sparse and time-intensive, b) ground-penetrating radar surveys, which have limited spatial coverage, or c) airborne LiDAR acquisition, which are expensive and may deteriorate in denser forests. We present the application of unmanned aerial vehicles in combination with structure-from-motion (SfM) methods to photogrammetrically map snow depth distribution in forested terrain. Two separate flights were carried out 10 days apart across a heterogeneous forested area of 900 x 500 m. Corresponding snow depth maps were derived using both, LiDAR-based and SfM-based DTM data, obtained during snow-off conditions. Manual measurements collected following each flight were used to validate the snow depth maps. Snow depths were resolved at 5cm resolution and forest snow depth distribution structures such as tree wells and other areas of preferential melt were represented well. Differential snow depth maps showed maximum ablation in the exposed south sides of trees and smaller differences in the centre of gaps and on the north side of trees. This new application of SfM to map snow depth distribution in forests demonstrates a straightforward method for obtaining information that was previously only available through manual spatially limited ground-based measurements. These methods could therefore be extended to more frequent observation of snow depths in forests as well as estimating snow accumulation and depletion rates.

The intensity dependence of lesion position shift during focused ultrasound surgery.

PubMed

Meaney, P M; Cahill, M D; ter Haar, G R

2000-03-01

Knowledge of the spatial distribution of intensity loss from an ultrasonic beam is critical for predicting lesion formation in focused ultrasound (US) surgery (FUS). To date, most models have used linear propagation models to predict intensity profiles required to compute the temporally varying temperature distributions used to compute thermal dose contours. These are used to predict the extent of thermal damage. However, these simulations fail to describe adequately the abnormal lesion formation behaviour observed during ex vivo experiments in cases for which the transducer drive levels are varied over a wide range. In such experiments, the extent of thermal damage has been observed to move significantly closer to the transducer with increased transducer drive levels than would be predicted using linear-propagation models. The first set of simulations described herein use the KZK (Khokhlov-Zabolotskaya-Kuznetsov) nonlinear propagation model with the parabolic approximation for highly focused US waves to demonstrate that both the peak intensity and the lesion positions do, indeed, move closer to the transducer. This illustrates that, for accurate modelling of heating during FUS, nonlinear effects should be considered. Additionally, a first order approximation has been employed that attempts to account for the abnormal heat deposition distributions that accompany high transducer drive level FUS exposures where cavitation and boiling may be present. The results of these simulations are presented. It is suggested that this type of approach may be a useful tool in understanding thermal damage mechanisms.

3D magnetic sources' framework estimation using Genetic Algorithm (GA)

NASA Astrophysics Data System (ADS)

Ponte-Neto, C. F.; Barbosa, V. C.

2008-05-01

We present a method for inverting total-field anomaly for determining simple 3D magnetic sources' framework such as: batholiths, dikes, sills, geological contacts, kimberlite and lamproite pipes. We use GA to obtain magnetic sources' frameworks and their magnetic features simultaneously. Specifically, we estimate the magnetization direction (inclination and declination) and the total dipole moment intensity, and the horizontal and vertical positions, in Cartesian coordinates , of a finite set of elementary magnetic dipoles. The spatial distribution of these magnetic dipoles composes the skeletal outlines of the geologic sources. We assume that the geologic sources have a homogeneous magnetization distribution and, thus all dipoles have the same magnetization direction and dipole moment intensity. To implement the GA, we use real-valued encoding with crossover, mutation, and elitism. To obtain a unique and stable solution, we set upper and lower bounds on declination and inclination of [0,360°] and [-90°, 90°], respectively. We also set the criterion of minimum scattering of the dipole-position coordinates, to guarantee that spatial distribution of the dipoles (defining the source skeleton) be as close as possible to continuous distribution. To this end, we fix the upper and lower bounds of the dipole moment intensity and we evaluate the dipole-position estimates. If the dipole scattering is greater than a value expected by the interpreter, the upper bound of the dipole moment intensity is reduced by 10 % of the latter. We repeat this procedure until the dipole scattering and the data fitting are acceptable. We apply our method to noise-corrupted magnetic data from simulated 3D magnetic sources with simple geometries and located at different depths. In tests simulating sources such as sphere and cube, all estimates of the dipole coordinates are agreeing with center of mass of these sources. To elongated-prismatic sources in an arbitrary direction, we estimate dipole-position coordinates coincident with principal axis of sources. In tests with synthetic data, simulating the magnetic anomaly yielded by intrusive 2D structures such as dikes and sills, the estimates of the dipole coordinates are coincident with the principal plane of these 2D sources. We also inverted the aeromagnetic data from Serra do Cabral, in southeastern, Brazil, and we estimated dipoles distributed on a horizontal plane at depth of 30 km, with inclination and declination of 59.1° and -48.0°, respectively. The results showed close agreement with previous interpretation.

Detection of infarct lesions from single MRI modality using inconsistency between voxel intensity and spatial location--a 3-D automatic approach.

PubMed

Shen, Shan; Szameitat, André J; Sterr, Annette

2008-07-01

Detection of infarct lesions using traditional segmentation methods is always problematic due to intensity similarity between lesions and normal tissues, so that multispectral MRI modalities were often employed for this purpose. However, the high costs of MRI scan and the severity of patient conditions restrict the collection of multiple images. Therefore, in this paper, a new 3-D automatic lesion detection approach was proposed, which required only a single type of anatomical MRI scan. It was developed on a theory that, when lesions were present, the voxel-intensity-based segmentation and the spatial-location-based tissue distribution should be inconsistent in the regions of lesions. The degree of this inconsistency was calculated, which indicated the likelihood of tissue abnormality. Lesions were identified when the inconsistency exceeded a defined threshold. In this approach, the intensity-based segmentation was implemented by the conventional fuzzy c-mean (FCM) algorithm, while the spatial location of tissues was provided by prior tissue probability maps. The use of simulated MRI lesions allowed us to quantitatively evaluate the performance of the proposed method, as the size and location of lesions were prespecified. The results showed that our method effectively detected lesions with 40-80% signal reduction compared to normal tissues (similarity index > 0.7). The capability of the proposed method in practice was also demonstrated on real infarct lesions from 15 stroke patients, where the lesions detected were in broad agreement with true lesions. Furthermore, a comparison to a statistical segmentation approach presented in the literature suggested that our 3-D lesion detection approach was more reliable. Future work will focus on adapting the current method to multiple sclerosis lesion detection.

Spatial patterns of cutaneous vibration during whole-hand haptic interactions

PubMed Central

Hayward, Vincent; Visell, Yon

2016-01-01

We investigated the propagation patterns of cutaneous vibration in the hand during interactions with touched objects. Prior research has highlighted the importance of vibrotactile signals during haptic interactions, but little is known of how vibrations propagate throughout the hand. Furthermore, the extent to which the patterns of vibrations reflect the nature of the objects that are touched, and how they are touched, is unknown. Using an apparatus comprised of an array of accelerometers, we mapped and analyzed spatial distributions of vibrations propagating in the skin of the dorsal region of the hand during active touch, grasping, and manipulation tasks. We found these spatial patterns of vibration to vary systematically with touch interactions and determined that it is possible to use these data to decode the modes of interaction with touched objects. The observed vibration patterns evolved rapidly in time, peaking in intensity within a few milliseconds, fading within 20–30 ms, and yielding interaction-dependent distributions of energy in frequency bands that span the range of vibrotactile sensitivity. These results are consistent with findings in perception research that indicate that vibrotactile information distributed throughout the hand can transmit information regarding explored and manipulated objects. The results may further clarify the role of distributed sensory resources in the perceptual recovery of object attributes during active touch, may guide the development of approaches to robotic sensing, and could have implications for the rehabilitation of the upper extremity. PMID:27035957

Distribution, abundance and habitat use of deep diving cetaceans in the North-East Atlantic

NASA Astrophysics Data System (ADS)

Rogan, Emer; Cañadas, Ana; Macleod, Kelly; Santos, M. Begoña; Mikkelsen, Bjarni; Uriarte, Ainhize; Van Canneyt, Olivier; Vázquez, José Antonio; Hammond, Philip S.

2017-07-01

In spite of their oceanic habitat, deep diving cetacean species have been found to be affected by anthropogenic activities, with potential population impacts of high intensity sounds generated by naval research and oil prospecting receiving the most attention. Improving the knowledge of the distribution and abundance of this poorly known group is an essential prerequisite to inform mitigation strategies seeking to minimize their spatial and temporal overlap with human activities. We provide for the first time abundance estimates for five deep diving cetacean species (sperm whale, long-finned pilot whale, northern bottlenose whale, Cuvier's beaked whale and Sowerby's beaked whale) using data from three dedicated cetacean sighting surveys that covered the oceanic and shelf waters of the North-East Atlantic. Density surface modelling was used to obtain model-based estimates of abundance and to explore the physical and biological characteristics of the habitat used by these species. Distribution of all species was found to be significantly related to depth, distance from the 2000m depth contour, the contour index (a measure of variability in the seabed) and sea surface temperature. Predicted distribution maps also suggest that there is little spatial overlap between these species. Our results represent the best abundance estimates for deep-diving whales in the North-East Atlantic, predict areas of high density during summer and constitute important baseline information to guide future risk assessments of human activities on these species, evaluate potential spatial and temporal trends and inform EU Directives and future conservation efforts.

Phase-image-based content-addressable holographic data storage

NASA Astrophysics Data System (ADS)

John, Renu; Joseph, Joby; Singh, Kehar

2004-03-01

We propose and demonstrate the use of phase images for content-addressable holographic data storage. Use of binary phase-based data pages with 0 and π phase changes, produces uniform spectral distribution at the Fourier plane. The absence of strong DC component at the Fourier plane and more intensity of higher order spatial frequencies facilitate better recording of higher spatial frequencies, and improves the discrimination capability of the content-addressable memory. This improves the results of the associative recall in a holographic memory system, and can give low number of false hits even for small search arguments. The phase-modulated pixels also provide an opportunity of subtraction among data pixels leading to better discrimination between similar data pages.

Application of a liquid crystal spatial light modulator to laser marking.

PubMed

Parry, Jonathan P; Beck, Rainer J; Shephard, Jonathan D; Hand, Duncan P

2011-04-20

Laser marking is demonstrated using a nanosecond (ns) pulse duration laser in combination with a liquid crystal spatial light modulator to generate two-dimensional patterns directly onto thin films and bulk metal surfaces. Previous demonstrations of laser marking with such devices have been limited to low average power lasers. Application in the ns regime enables more complex, larger scale marks to be generated with more widely available and industrially proven laser systems. The dynamic nature of the device is utilized to improve mark quality by reducing the impact of the inherently speckled intensity distribution across the generated image and reduce thermal effects in the marked surface. © 2011 Optical Society of America

Distribution of Aboveground Live Biomass in the Amazon Basin

NASA Technical Reports Server (NTRS)

Saatchi, S. S.; Houghton, R. A.; DosSantos Alvala, R. C.; Soares, J. V.; Yu, Y.

2007-01-01

The amount and spatial distribution of forest biomass in the Amazon basin is a major source of uncertainty in estimating the flux of carbon released from land-cover and land-use change. Direct measurements of aboveground live biomass (AGLB) are limited to small areas of forest inventory plots and site-specific allometric equations that cannot be readily generalized for the entire basin. Furthermore, there is no spaceborne remote sensing instrument that can measure tropical forest biomass directly. To determine the spatial distribution of forest biomass of the Amazon basin, we report a method based on remote sensing metrics representing various forest structural parameters and environmental variables, and more than 500 plot measurements of forest biomass distributed over the basin. A decision tree approach was used to develop the spatial distribution of AGLB for seven distinct biomass classes of lowland old-growth forests with more than 80% accuracy. AGLB for other vegetation types, such as the woody and herbaceous savanna and secondary forests, was directly estimated with a regression based on satellite data. Results show that AGLB is highest in Central Amazonia and in regions to the east and north, including the Guyanas. Biomass is generally above 300Mgha(sup 1) here except in areas of intense logging or open floodplains. In Western Amazonia, from the lowlands of Peru, Ecuador, and Colombia to the Andean mountains, biomass ranges from 150 to 300Mgha(sup 1). Most transitional and seasonal forests at the southern and northwestern edges of the basin have biomass ranging from 100 to 200Mgha(sup 1). The AGLB distribution has a significant correlation with the length of the dry season. We estimate that the total carbon in forest biomass of the Amazon basin, including the dead and below ground biomass, is 86 PgC with +/- 20% uncertainty.

Multivariate hydrological frequency analysis for extreme events using Archimedean copula. Case study: Lower Tunjuelo River basin (Colombia)

NASA Astrophysics Data System (ADS)

Gómez, Wilmar

2017-04-01

By analyzing the spatial and temporal variability of extreme precipitation events we can prevent or reduce the threat and risk. Many water resources projects require joint probability distributions of random variables such as precipitation intensity and duration, which can not be independent with each other. The problem of defining a probability model for observations of several dependent variables is greatly simplified by the joint distribution in terms of their marginal by taking copulas. This document presents a general framework set frequency analysis bivariate and multivariate using Archimedean copulas for extreme events of hydroclimatological nature such as severe storms. This analysis was conducted in the lower Tunjuelo River basin in Colombia for precipitation events. The results obtained show that for a joint study of the intensity-duration-frequency, IDF curves can be obtained through copulas and thus establish more accurate and reliable information from design storms and associated risks. It shows how the use of copulas greatly simplifies the study of multivariate distributions that introduce the concept of joint return period used to represent the needs of hydrological designs properly in frequency analysis.

Evolution of arbitrary moments of radiant intensity distribution for partially coherent general beams in atmospheric turbulence

NASA Astrophysics Data System (ADS)

Dan, Youquan; Xu, Yonggen

2018-04-01

The evolution law of arbitrary order moments of the Wigner distribution function, which can be applied to the different spatial power spectra, is obtained for partially coherent general beams propagating in atmospheric turbulence using the extended Huygens-Fresnel principle. A coupling coefficient of radiant intensity distribution (RID) in turbulence is introduced. Analytical expressions of the evolution of the first five-order moments, kurtosis parameter, coupling coefficient of RID for general beams in turbulence are derived, and the formulas are applied to Airy beams. Results show that there exist two types for general beams in turbulence. A larger value of kurtosis parameter for Airy beams also reveals that coupling effect due to turbulence is stronger. Both theoretical analysis and numerical results show that the maximum value of kurtosis parameter for an Airy beam in turbulence is independent of turbulence strength parameter and is only determined by inner scale of turbulence. Relative angular spread, kurtosis and coupling coefficient are less influenced by turbulence for Airy beams with a smaller decay factor and a smaller initial width of the first lobe.

Development of monitoring method of spatial neutron distribution in neutrons-gamma rays mixed field using imaging plate for NCT--depression of the field.

PubMed

Tanaka, Kenichi; Endo, Satoru; Hoshi, Masaharu; Takada, Jun

2011-12-01

The degree of depression in the neutron field caused by neutron absorption in the materials of an imaging plate (IP) was investigated using MCNP-4C. Consequently, the IP doped with Gd, which reproduced the distribution of (157)Gd(n,γ)(158)Gd reaction rate in the previous study, depresses the relative distribution by about 50%. The depression for the IP in which Gd is replaced with similar amount of B atoms was estimated to be about 10%. The signal intensity for this IP is estimated to be at a similar level with that for Gd-doped IP. Copyright © 2011 Elsevier Ltd. All rights reserved.

Spatial Intensity Duration Frequency Relationships Using Hierarchical Bayesian Analysis for Urban Areas

NASA Astrophysics Data System (ADS)

Rupa, Chandra; Mujumdar, Pradeep

2016-04-01

In urban areas, quantification of extreme precipitation is important in the design of storm water drains and other infrastructure. Intensity Duration Frequency (IDF) relationships are generally used to obtain design return level for a given duration and return period. Due to lack of availability of extreme precipitation data for sufficiently large number of years, estimating the probability of extreme events is difficult. Typically, a single station data is used to obtain the design return levels for various durations and return periods, which are used in the design of urban infrastructure for the entire city. In an urban setting, the spatial variation of precipitation can be high; the precipitation amounts and patterns often vary within short distances of less than 5 km. Therefore it is crucial to study the uncertainties in the spatial variation of return levels for various durations. In this work, the extreme precipitation is modeled spatially using the Bayesian hierarchical analysis and the spatial variation of return levels is studied. The analysis is carried out with Block Maxima approach for defining the extreme precipitation, using Generalized Extreme Value (GEV) distribution for Bangalore city, Karnataka state, India. Daily data for nineteen stations in and around Bangalore city is considered in the study. The analysis is carried out for summer maxima (March - May), monsoon maxima (June - September) and the annual maxima rainfall. In the hierarchical analysis, the statistical model is specified in three layers. The data layer models the block maxima, pooling the extreme precipitation from all the stations. In the process layer, the latent spatial process characterized by geographical and climatological covariates (lat-lon, elevation, mean temperature etc.) which drives the extreme precipitation is modeled and in the prior level, the prior distributions that govern the latent process are modeled. Markov Chain Monte Carlo (MCMC) algorithm (Metropolis Hastings algorithm within a Gibbs sampler) is used to obtain the samples of parameters from the posterior distribution of parameters. The spatial maps of return levels for specified return periods, along with the associated uncertainties, are obtained for the summer, monsoon and annual maxima rainfall. Considering various covariates, the best fit model is selected using Deviance Information Criteria. It is observed that the geographical covariates outweigh the climatological covariates for the monsoon maxima rainfall (latitude and longitude). The best covariates for summer maxima and annual maxima rainfall are mean summer precipitation and mean monsoon precipitation respectively, including elevation for both the cases. The scale invariance theory, which states that statistical properties of a process observed at various scales are governed by the same relationship, is used to disaggregate the daily rainfall to hourly scales. The spatial maps of the scale are obtained for the study area. The spatial maps of IDF relationships thus generated are useful in storm water designs, adequacy analysis and identifying the vulnerable flooding areas.

Esophageal wall dose-surface maps do not improve the predictive performance of a multivariable NTCP model for acute esophageal toxicity in advanced stage NSCLC patients treated with intensity-modulated (chemo-)radiotherapy.

PubMed

Dankers, Frank; Wijsman, Robin; Troost, Esther G C; Monshouwer, René; Bussink, Johan; Hoffmann, Aswin L

2017-05-07

In our previous work, a multivariable normal-tissue complication probability (NTCP) model for acute esophageal toxicity (AET) Grade  ⩾2 after highly conformal (chemo-)radiotherapy for non-small cell lung cancer (NSCLC) was developed using multivariable logistic regression analysis incorporating clinical parameters and mean esophageal dose (MED). Since the esophagus is a tubular organ, spatial information of the esophageal wall dose distribution may be important in predicting AET. We investigated whether the incorporation of esophageal wall dose-surface data with spatial information improves the predictive power of our established NTCP model. For 149 NSCLC patients treated with highly conformal radiation therapy esophageal wall dose-surface histograms (DSHs) and polar dose-surface maps (DSMs) were generated. DSMs were used to generate new DSHs and dose-length-histograms that incorporate spatial information of the dose-surface distribution. From these histograms dose parameters were derived and univariate logistic regression analysis showed that they correlated significantly with AET. Following our previous work, new multivariable NTCP models were developed using the most significant dose histogram parameters based on univariate analysis (19 in total). However, the 19 new models incorporating esophageal wall dose-surface data with spatial information did not show improved predictive performance (area under the curve, AUC range 0.79-0.84) over the established multivariable NTCP model based on conventional dose-volume data (AUC  =  0.84). For prediction of AET, based on the proposed multivariable statistical approach, spatial information of the esophageal wall dose distribution is of no added value and it is sufficient to only consider MED as a predictive dosimetric parameter.

Esophageal wall dose-surface maps do not improve the predictive performance of a multivariable NTCP model for acute esophageal toxicity in advanced stage NSCLC patients treated with intensity-modulated (chemo-)radiotherapy

NASA Astrophysics Data System (ADS)

Dankers, Frank; Wijsman, Robin; Troost, Esther G. C.; Monshouwer, René; Bussink, Johan; Hoffmann, Aswin L.

2017-05-01

In our previous work, a multivariable normal-tissue complication probability (NTCP) model for acute esophageal toxicity (AET) Grade  ⩾2 after highly conformal (chemo-)radiotherapy for non-small cell lung cancer (NSCLC) was developed using multivariable logistic regression analysis incorporating clinical parameters and mean esophageal dose (MED). Since the esophagus is a tubular organ, spatial information of the esophageal wall dose distribution may be important in predicting AET. We investigated whether the incorporation of esophageal wall dose-surface data with spatial information improves the predictive power of our established NTCP model. For 149 NSCLC patients treated with highly conformal radiation therapy esophageal wall dose-surface histograms (DSHs) and polar dose-surface maps (DSMs) were generated. DSMs were used to generate new DSHs and dose-length-histograms that incorporate spatial information of the dose-surface distribution. From these histograms dose parameters were derived and univariate logistic regression analysis showed that they correlated significantly with AET. Following our previous work, new multivariable NTCP models were developed using the most significant dose histogram parameters based on univariate analysis (19 in total). However, the 19 new models incorporating esophageal wall dose-surface data with spatial information did not show improved predictive performance (area under the curve, AUC range 0.79-0.84) over the established multivariable NTCP model based on conventional dose-volume data (AUC  =  0.84). For prediction of AET, based on the proposed multivariable statistical approach, spatial information of the esophageal wall dose distribution is of no added value and it is sufficient to only consider MED as a predictive dosimetric parameter.

[Distribution pattern of riparian invasive plants in Luanhe Basin, North China and its relationship with environment].

PubMed

Ren, Ying; He, Ping; Xu, Jie; Jia, Jiao

2017-06-18

In this study, the invasive plant species from the riparian vegetation in 56 sampling sites of Luanhe Basin were identified, and the correlations between their composition, spatial distribution and environmental factors were explored. In the basin, a total of 26 invasive species were registered, which belonged to 19 genera and 12 families, and 73.1% of them were annual plants. Asteraceae and Amaranthaceae were the two dominant families with the most invasive species, attributing to 50% of the total invasive species. Amaranthus retroflexus, Bidens frondosa and Chenopodium serotinum appeared with the highest frequencies. The number of invasive species and the invasive intensity at each site were significantly negatively correlated with the altitude. The distribution of invasive plants was significantly influenced by the intensity of human activities. The invasive plants were mainly distributed in the plain area, shallow mountainous area with many reservoirs, and the mountainous area with developed tourism around Chengde City, meanwhile, only few species with broad ecological amplitude existed in the plateau area. In general, species with higher invasive grades were mainly distributed in low and medium altitude areas below 400 m. Except for A. retroflexus, no high-grade invasive plants were discovered in high altitude area so far.

Three-dimensional modeling and quantitative analysis of gap junction distributions in cardiac tissue.

PubMed

Lackey, Daniel P; Carruth, Eric D; Lasher, Richard A; Boenisch, Jan; Sachse, Frank B; Hitchcock, Robert W

2011-11-01

Gap junctions play a fundamental role in intercellular communication in cardiac tissue. Various types of heart disease including hypertrophy and ischemia are associated with alterations of the spatial arrangement of gap junctions. Previous studies applied two-dimensional optical and electron-microscopy to visualize gap junction arrangements. In normal cardiomyocytes, gap junctions were primarily found at cell ends, but can be found also in more central regions. In this study, we extended these approaches toward three-dimensional reconstruction of gap junction distributions based on high-resolution scanning confocal microscopy and image processing. We developed methods for quantitative characterization of gap junction distributions based on analysis of intensity profiles along the principal axes of myocytes. The analyses characterized gap junction polarization at cell ends and higher-order statistical image moments of intensity profiles. The methodology was tested in rat ventricular myocardium. Our analysis yielded novel quantitative data on gap junction distributions. In particular, the analysis demonstrated that the distributions exhibit significant variability with respect to polarization, skewness, and kurtosis. We suggest that this methodology provides a quantitative alternative to current approaches based on visual inspection, with applications in particular in characterization of engineered and diseased myocardium. Furthermore, we propose that these data provide improved input for computational modeling of cardiac conduction.

Implications of the SPEAR FUV Maps on Our Understanding of the ISM

NASA Astrophysics Data System (ADS)

Korpela, Eric J.; Sirk, Martin; Edelstein, Jerry; Seon, Kwangil; Min, Kyoung-Wook; Han, Wonyong

2009-08-01

The distribution of a low-density transition temperature (104.5-105.5 K) gas in the interstellar medium conveys the character and evolution of diffuse matter in the Galaxy. This difficult to observe component of the ISM emits mainly in the far-ultraviolet (FUV) (912-1800 A˚) band. We describe spectral maps of FUV emission lines from the highly ionized species CIV and OVI likely to be the dominant cooling mechanisms of transition temperature gas in the ISM. The maps were obtained using an orbital spectrometer, SPEAR, that was launched in 2003 and has observed the FUV sky with a spectral resolution of ~550 and an angular resolution of 10'. We compare distribution of flux in these maps with three basic models of the distribution of transition temperature gas. We find that the median distribution of CIV and OVI emission is consistent with the spatial distribution and line ratios expected from a McKee-Ostriker (MO) type model of evaporative interfaces. However, the intensities are a factor of three higher than would be expected at the MO preferred parameters. Some high intensity regions are clearly associated with supernova remnants and superbubble structures. Others may indicate regions where gas is cooling through the transition temperature.

Computer Generated Holography with Intensity-Graded Patterns

PubMed Central

Conti, Rossella; Assayag, Osnath; de Sars, Vincent; Guillon, Marc; Emiliani, Valentina

2016-01-01

Computer Generated Holography achieves patterned illumination at the sample plane through phase modulation of the laser beam at the objective back aperture. This is obtained by using liquid crystal-based spatial light modulators (LC-SLMs), which modulate the spatial phase of the incident laser beam. A variety of algorithms is employed to calculate the phase modulation masks addressed to the LC-SLM. These algorithms range from simple gratings-and-lenses to generate multiple diffraction-limited spots, to iterative Fourier-transform algorithms capable of generating arbitrary illumination shapes perfectly tailored on the base of the target contour. Applications for holographic light patterning include multi-trap optical tweezers, patterned voltage imaging and optical control of neuronal excitation using uncaging or optogenetics. These past implementations of computer generated holography used binary input profile to generate binary light distribution at the sample plane. Here we demonstrate that using graded input sources, enables generating intensity graded light patterns and extend the range of application of holographic light illumination. At first, we use intensity-graded holograms to compensate for LC-SLM position dependent diffraction efficiency or sample fluorescence inhomogeneity. Finally we show that intensity-graded holography can be used to equalize photo evoked currents from cells expressing different levels of chanelrhodopsin2 (ChR2), one of the most commonly used optogenetics light gated channels, taking into account the non-linear dependence of channel opening on incident light. PMID:27799896

Evaluating the intensity of fire at the Acheulian site of Gesher Benot Ya'aqov—Spatial and thermoluminescence analyses

PubMed Central

Richter, Daniel; Goren-Inbar, Naama

2017-01-01

This manuscript presents an attempt to evaluate the intensity of fire through spatial patterning and thermoluminescence methodology. Previous studies of Layer II-6 Level 2 at the Acheulian site of Gesher Benot Ya‘aqov suggested that hominins differentiated their activities across space, including multiple activities around a hearth reconstructed on the basis of the distribution of burned flint artifacts. A transect of ~4 m was extended from the center of the reconstructed hearth of Level 2 to its periphery in order to examine the intensity of fire. Burned and unburned flint microartifacts were sampled along this transect. The results of earlier and current thermoluminescence (TL) analysis demonstrate a general agreement with the macroscopic determination of burning, indicating that the possibility of misinterpretation based on macroscopic observations is negligible. The TL signal from flint microartifacts close to the hearth’s center shows unambiguous signs of strong heating, whereas with increasing distance from the hearth the TL signal can be interpreted as a result of decreasing temperatures and/or shorter durations of exposure to fire in addition to a decreasing number of flints showing fire damage. Our study shows that TL analysis can identify some variation in fire intensity, which allows a more precise classification of burned flint microartifacts with respect to their heating history. PMID:29145432

A spatial panel ordered-response model with application to the analysis of urban land-use development intensity patterns

NASA Astrophysics Data System (ADS)

Ferdous, Nazneen; Bhat, Chandra R.

2013-01-01

This paper proposes and estimates a spatial panel ordered-response probit model with temporal autoregressive error terms to analyze changes in urban land development intensity levels over time. Such a model structure maintains a close linkage between the land owner's decision (unobserved to the analyst) and the land development intensity level (observed by the analyst) and accommodates spatial interactions between land owners that lead to spatial spillover effects. In addition, the model structure incorporates spatial heterogeneity as well as spatial heteroscedasticity. The resulting model is estimated using a composite marginal likelihood (CML) approach that does not require any simulation machinery and that can be applied to data sets of any size. A simulation exercise indicates that the CML approach recovers the model parameters very well, even in the presence of high spatial and temporal dependence. In addition, the simulation results demonstrate that ignoring spatial dependency and spatial heterogeneity when both are actually present will lead to bias in parameter estimation. A demonstration exercise applies the proposed model to examine urban land development intensity levels using parcel-level data from Austin, Texas.

Computing Pathways for Urban Decarbonization.

NASA Astrophysics Data System (ADS)

Cremades, R.; Sommer, P.

2016-12-01

Urban areas emit roughly three quarters of global carbon emissions. Cities are crucial elements for a decarbonized society. Urban expansion and related transportation needs lead to increased energy use, and to carbon-intensive lock-ins that create barriers for climate change mitigation globally. The authors present the Integrated Urban Complexity (IUC) model, based on self-organizing Cellular Automata (CA), and use it to produce a new kind of spatially explicit Transformation Pathways for Urban Decarbonization (TPUD). IUC is based on statistical evidence relating the energy needed for transportation with the spatial distribution of population, specifically IUC incorporates variables from complexity science related to urban form, like the slope of the rank-size rule or spatial entropy, which brings IUC a step beyond existing models. The CA starts its evolution with real-world urban land use and population distribution data from the Global Human Settlement Layer. Thus, the IUC model runs over existing urban settlements, transforming the spatial distribution of population so the energy consumption for transportation is minimized. The statistical evidence that governs the evolution of the CA departs from the database of the International Association of Public Transport. A selected case is presented using Stuttgart (Germany) as an example. The results show how IUC varies urban density in those places where it improves the performance of crucial parameters related to urban form, producing a TPUD that shows where the spatial distribution of population should be modified with a degree of detail of 250 meters of cell size. The TPUD shows how the urban complex system evolves over time to minimize energy consumption for transportation. The resulting dynamics or urban decarbonization show decreased energy per capita, although total energy increases for increasing population. The results provide innovative insights: by checking current urban planning against a TPUD, urban planners could understand where existing plans contradict the Agenda 2030, primarily the Sustainable Development Goals (SDGs) Climate Action (SDG 13), and Sustainable Cities and Communities (SDG 11). For the first time, evidence-based transformation pathways are produced to decarbonize cities.

Can animal habitat use patterns influence their vulnerability to extreme climate events? An estuarine sportfish case study.

PubMed

Boucek, Ross E; Heithaus, Michael R; Santos, Rolando; Stevens, Philip; Rehage, Jennifer S

2017-10-01

Global climate forecasts predict changes in the frequency and intensity of extreme climate events (ECEs). The capacity for specific habitat patches within a landscape to modulate stressors from extreme climate events, and animal distribution throughout habitat matrices during events, could influence the degree of population level effects following the passage of ECEs. Here, we ask (i) does the intensity of stressors of an ECE vary across a landscape? And (ii) Do habitat use patterns of a mobile species influence their vulnerability to ECEs? Specifically, we measured how extreme cold spells might interact with temporal variability in habitat use to affect populations of a tropical, estuarine-dependent large-bodied fish Common Snook, within Everglades National Park estuaries (FL US). We examined temperature variation across the estuary during cold disturbances with different degrees of severity, including an extreme cold spell. Second, we quantified Snook distribution patterns when the passage of ECEs is most likely to occur from 2012 to 2016 using passive acoustic tracking. Our results revealed spatial heterogeneity in the intensity of temperature declines during cold disturbances, with some habitats being consistently 3-5°C colder than others. Surprisingly, Snook distributions during periods of greatest risk to experience an extreme cold event varied among years. During the winters of 2013-2014 and 2014-2015 a greater proportion of Snook occurred in the colder habitats, while the winters of 2012-2013 and 2015-2016 featured more Snook observed in the warmest habitats. This study shows that Snook habitat use patterns could influence vulnerability to extreme cold events, however, whether Snook habitat use increases or decreases their vulnerability to disturbance depends on the year, creating temporally dynamic vulnerability. Faunal global change research should address the spatially explicit nature of extreme climate events and animal habitat use patterns to identify potential mechanisms that may influence population effects following these disturbances. Published 2017. This article is a U.S. Government work and is in the public domain in the USA.

Spatial Distribution Patterns in the Very Rare and Species-Rich Picea chihuahuana Tree Community (Mexico).

PubMed

Wehenkel, Christian; Brazão-Protázio, João Marcelo; Carrillo-Parra, Artemio; Martínez-Guerrero, José Hugo; Crecente-Campo, Felipe

2015-01-01

The very rare Mexican Picea chihuahuana tree community covers an area of no more than 300 ha in the Sierra Madre Occidental. This special tree community has been the subject of several studies aimed at learning more about the genetic structure and ecology of the species and the potential effects of climate change. The spatial distribution of trees is a result of many ecological processes and can affect the degree of competition between neighbouring trees, tree density, variability in size and distribution, regeneration, survival, growth, mortality, crown formation and the biological diversity within forest communities. Numerous scale-dependent measures have been established in order to describe spatial forest structure. The overall aim of most of these studies has been to obtain data to help design preservation and conservation strategies. In this study, we examined the spatial distribution pattern of trees in the P. chihuahuana tree community in 12 localities, in relation to i) tree stand density, ii) diameter distribution (vertical structure), iii) tree species diversity, iv) geographical latitude and v) tree dominance at a fine scale (in 0.25 ha plots), with the aim of obtaining a better understanding of the complex ecosystem processes and biological diversity. Because of the strongly mixed nature of this tree community, which often produces low population densities of each tree species and random tree fall gaps caused by tree death, we expect aggregated patterns in individual Picea chihuahuana trees and in the P. chihuahuana tree community, repulsive Picea patterns to other tree species and repulsive patterns of young to adult trees. Each location was represented by one plot of 50 x 50 m (0.25 ha) established in the centre of the tree community. The findings demonstrate that the hypothesis of aggregated tree pattern is not applicable to the mean pattern measured by Clark-Evans index, Uniform Angle index and Mean Directional index of the uneven-aged P. chihuahuana trees and P. chihuahuana tree community and but to specific spatial scales measured by the univariate L-function. The spatial distribution pattern of P. chihuahuana trees was found to be independent of patches of other tree species measured by the bivariate L-function. The spatial distribution was not significantly related to tree density, diameter distribution or tree species diversity. The index of Clark and Evans decreased significantly from the southern to northern plots containing all tree species. Self-thinning due to intra and inter-specific competition-induced mortality is probably the main cause of the decrease in aggregation intensity during the course of population development in this tree community. We recommend the use of larger sampling plots (> 0.25 ha) in uneven-aged and species-rich forest ecosystems to detect less obvious, but important, relationships between spatial tree pattern and functioning and diversity in these forests.

Spatial Distribution Patterns in the Very Rare and Species-Rich Picea chihuahuana Tree Community (Mexico)

PubMed Central

Wehenkel, Christian; Brazão-Protázio, João Marcelo; Carrillo-Parra, Artemio; Martínez-Guerrero, José Hugo; Crecente-Campo, Felipe

2015-01-01

The very rare Mexican Picea chihuahuana tree community covers an area of no more than 300 ha in the Sierra Madre Occidental. This special tree community has been the subject of several studies aimed at learning more about the genetic structure and ecology of the species and the potential effects of climate change. The spatial distribution of trees is a result of many ecological processes and can affect the degree of competition between neighbouring trees, tree density, variability in size and distribution, regeneration, survival, growth, mortality, crown formation and the biological diversity within forest communities. Numerous scale-dependent measures have been established in order to describe spatial forest structure. The overall aim of most of these studies has been to obtain data to help design preservation and conservation strategies. In this study, we examined the spatial distribution pattern of trees in the P. chihuahuana tree community in 12 localities, in relation to i) tree stand density, ii) diameter distribution (vertical structure), iii) tree species diversity, iv) geographical latitude and v) tree dominance at a fine scale (in 0.25 ha plots), with the aim of obtaining a better understanding of the complex ecosystem processes and biological diversity. Because of the strongly mixed nature of this tree community, which often produces low population densities of each tree species and random tree fall gaps caused by tree death, we expect aggregated patterns in individual Picea chihuahuana trees and in the P. chihuahuana tree community, repulsive Picea patterns to other tree species and repulsive patterns of young to adult trees. Each location was represented by one plot of 50 x 50 m (0.25 ha) established in the centre of the tree community. The findings demonstrate that the hypothesis of aggregated tree pattern is not applicable to the mean pattern measured by Clark-Evans index, Uniform Angle index and Mean Directional index of the uneven-aged P. chihuahuana trees and P. chihuahuana tree community and but to specific spatial scales measured by the univariate L-function. The spatial distribution pattern of P. chihuahuana trees was found to be independent of patches of other tree species measured by the bivariate L-function. The spatial distribution was not significantly related to tree density, diameter distribution or tree species diversity. The index of Clark and Evans decreased significantly from the southern to northern plots containing all tree species. Self-thinning due to intra and inter-specific competition-induced mortality is probably the main cause of the decrease in aggregation intensity during the course of population development in this tree community. We recommend the use of larger sampling plots (> 0.25 ha) in uneven-aged and species-rich forest ecosystems to detect less obvious, but important, relationships between spatial tree pattern and functioning and diversity in these forests. PMID:26496189

Imaging three-dimensional light propagation through periodic nanohole arrays using scanning aperture microscopy

PubMed Central

Chowdhury, Mustafa H.; Catchmark, Jeffrey M.; Lakowicz, Joseph R.

2009-01-01

The authors introduce a technique for three-dimensional (3D) imaging of the light transmitted through periodic nanoapertures using a scanning probe to perform optical sectioning microscopy. For a 4×4 nanohole array, the transmitted light displays intensity modulations along the propagation axis, with the maximum intensity occurring at 450 μm above the surface. The propagating fields show low divergence, suggesting a beaming effect induced by the array. At distances within 25 μm from the surface, they observe subwavelength confinement of light propagating from the individual nanoholes. Hence, this technique can potentially be used to map the 3D distribution of propagating light, with high spatial resolution. PMID:19696912

Electron beam dispersion measurements in nitrogen using two-dimensional imaging of N2(+) fluorescence

NASA Technical Reports Server (NTRS)

Clapp, L. H.; Twiss, R. G.; Cattolica, R. J.

1991-01-01

Experimental results are presented related to the radial spread of fluorescence excited by 10 and 20 KeV electron beams passing through nonflowing rarefied nitrogen at 293 K. An imaging technique for obtaining species distributions from measured beam-excited fluorescence is described, based on a signal inversion scheme mathematically equivalent to the inversion of the Abel integral equation. From fluorescence image data, measurements of beam radius, integrated signal intensity, and spatially resolved distributions of N2(+) first-negative-band fluorescence-emitting species have been made. Data are compared with earlier measurements and with an heuristic beam spread model.

[94 km Brillouin distributed optical fiber sensors based on ultra-long fiber ring laser pumping].

PubMed

Yuan, Cheng-Xu; Wang, Zi-Nan; Jia, Xin-Hong; Li, Jin; Yan, Xiao-Dong; Cui, An-Bin

2014-05-01

A novel optical amplification configuration based on ultra-long fiber laser with a ring cavity was proposed and applied to Brillouin optical time-domain analysis (BOTDA) sensing system, in order to extend the measurement distance significantly. The parameters used in the experiment were optimized, considering the main limitations of the setup, such as depletion, self-phase modulation (SPM) and pump-signal relative intensity noise (RIN) transfer. Through analyzing Brillouin gain spectrum, we demonstrated distributed sensing over 94 km of standard single-mode fiber with 3 meter spatial resolution and strain/temperature accuracy of 28 /1. 4 degree C.

Experimental Retrieval of Target Structure Information from Laser-Induced Rescattered Photoelectron Momentum Distributions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okunishi, M.; Pruemper, G.; Shimada, K.

We have measured two-dimensional photoelectron momentum spectra of Ne, Ar, and Xe generated by 800-nm, 100-fs laser pulses and succeeded in identifying the spectral ridge region (back-rescattered ridges) which marks the location of the returning electrons that have been backscattered at their maximum kinetic energies. We demonstrate that the structural information, in particular the differential elastic scattering cross sections of the target ion by free electrons, can be accurately extracted from the intensity distributions of photoelectrons on the ridges, thus effecting a first step toward laser-induced self-imaging of the target, with unprecedented spatial and temporal resolutions.

Collimated Propagation of Fast Electron Beams Accelerated by High-Contrast Laser Pulses in Highly Resistive Shocked Carbon.

PubMed

Vaisseau, X; Morace, A; Touati, M; Nakatsutsumi, M; Baton, S D; Hulin, S; Nicolaï, Ph; Nuter, R; Batani, D; Beg, F N; Breil, J; Fedosejevs, R; Feugeas, J-L; Forestier-Colleoni, P; Fourment, C; Fujioka, S; Giuffrida, L; Kerr, S; McLean, H S; Sawada, H; Tikhonchuk, V T; Santos, J J

2017-05-19

Collimated transport of ultrahigh intensity electron current was observed in cold and in laser-shocked vitreous carbon, in agreement with simulation predictions. The fast electron beams were created by coupling high-intensity and high-contrast laser pulses onto copper-coated cones drilled into the carbon samples. The guiding mechanism-observed only for times before the shock breakout at the inner cone tip-is due to self-generated resistive magnetic fields of ∼0.5-1  kT arising from the intense currents of fast electrons in vitreous carbon, by virtue of its specific high resistivity over the range of explored background temperatures. The spatial distribution of the electron beams, injected through the samples at different stages of compression, was characterized by side-on imaging of hard x-ray fluorescence.

Colocalization of outflow segmentation and pores along the inner wall of Schlemm's canal.

PubMed

Braakman, Sietse T; Read, A Thomas; Chan, Darren W-H; Ethier, C Ross; Overby, Darryl R

2015-01-01

All aqueous humor draining through the conventional outflow pathway must cross the endothelium of Schlemm's canal (SC), likely by passing through micron-sized transendothelial pores. SC pores are non-uniformly distributed along the inner wall endothelium, but it is unclear how the distribution of pores relates to the non-uniform or segmental distribution of aqueous humor outflow through the trabecular meshwork. It is hypothesized that regions in the juxtacanalicular tissue (JCT) with higher local outflow should coincide with regions of greater inner wall pore density compared to JCT regions with lower outflow. Three pairs of non-glaucomatous human donor eyes were perfused at 8 mmHg with fluorescent tracer nanospheres to decorate local patterns of outflow segmentation through the JCT. The inner wall was stained for CD31 and/or vimentin and imaged en face using confocal and scanning electron microscopy (SEM). Confocal and SEM images were spatially registered to examine the spatial relationship between inner wall pore density and tracer intensity in the underlying JCT. For each eye, tracer intensity, pore density (n) and pore diameter (D) (for both transcellular "I" and paracellular "B" pores) were measured in 4-7 regions of interest (ROIs; 50 × 150 μm each). Analysis of covariance was used to examine the relationship between tracer intensity and pore density, as well as the relationship between tracer intensity and three pore metrics (nD, nD(2) and nD(3)) that represent the local hydraulic conductivity of the outflow pathway as predicted by various hydrodynamic models. Tracer intensity in the JCT correlated positively with local pore density when considering total pores (p = 0.044) and paracellular B pores on their own (p = 0.016), but not transcellular I-pores on their own (p = 0.54). Local hydraulic conductivity as predicted by the three hydrodynamic models all showed a significant positive correlation with tracer intensity when considering total pores and B-pores (p < 0.0015 and p < 10(-4)) but not I-pores (p > 0.38). These data suggest that aqueous humor passes through micron-sized pores in the inner wall endothelium of SC. Paracellular B-pores appear to have a dominant contribution towards transendothelial filtration across the inner wall relative to transcellular I-pores. Impaired pore formation, as previously described in glaucomatous SC cells, may thereby contribute to greater outflow heterogeneity, outflow obstruction, and IOP elevation in glaucoma. Copyright © 2014 Elsevier Ltd. All rights reserved.

Colocalization of Outflow Segmentation and Pores Along the Inner Wall of Schlemm’s Canal

PubMed Central

Braakman, Sietse T.; Read, A. Thomas; Chan, Darren W.-H.; Ethier, C. Ross; Overby, Darryl R.

2014-01-01

All aqueous humor draining through the conventional outflow pathway must cross the endothelium of Schlemm’s canal (SC), likely by passing through micron-sized transendothelial pores. SC pores are non-uniformly distributed along the inner wall endothelium, but it is unclear how the distribution of pores relates to the non-uniform or segmental distribution of aqueous humor outflow through the trabecular meshwork. It is hypothesized that regions in the juxtacanalicular tissue (JCT) with higher local outflow should coincide with regions of greater inner wall pore density compared to JCT regions with lower outflow. Three pairs of non-glaucomatous human donor eyes were perfused at 8 mmHg with fluorescent tracer nanospheres to decorate local patterns of outflow segmentation through the JCT. The inner wall was stained for CD31 and/or vimentin and imaged en face using confocal and scanning electron microscopy (SEM). Confocal and SEM images were spatially registered to examine the spatial relationship between inner wall pore density and tracer intensity in the underlying JCT. For each eye, tracer intensity, pore density (n) and pore diameter (D) (for both transcellular “I” and paracellular “B” pores) were measured in 4-7 regions of interest (ROIs; 50 × 150 μm each). Analysis of covariance was used to examine the relationship between tracer intensity and pore density, as well as the relationship between tracer intensity and three pore metrics (nD, nD2 and nD3) that represent the local hydraulic conductivity of the outflow pathway as predicted by various hydrodynamic models. Tracer intensity in the JCT correlated positively with local pore density when considering total pores (p = 0.044) and paracellular B pores on their own (p = 0.016), but not transcellular I-pores on their own (p = 0.54). Local hydraulic conductivity as predicted by the three hydrodynamic models all showed a significant positive correlation with tracer intensity when considering total pores and B-pores (p < 0.0015 and p < 10−4) but not I-pores (p > 0.38). These data suggest that aqueous humor passes through micron-sized pores in the inner wall endothelium of SC. Paracellular B-pores appear to have a dominant contribution towards transendothelial filtration across the inner wall relative to transcellular I-pores. Impaired pore formation, as previously described in glaucomatous SC cells, may thereby contribute to greater outflow heterogeneity, outflow obstruction, and IOP elevation in glaucoma. PMID:25450060

Modeling of light distribution in the brain for topographical imaging

NASA Astrophysics Data System (ADS)

Okada, Eiji; Hayashi, Toshiyuki; Kawaguchi, Hiroshi

2004-07-01

Multi-channel optical imaging system can obtain a topographical distribution of the activated region in the brain cortex by a simple mapping algorithm. Near-infrared light is strongly scattered in the head and the volume of tissue that contributes to the change in the optical signal detected with source-detector pair on the head surface is broadly distributed in the brain. This scattering effect results in poor resolution and contrast in the topographic image of the brain activity. We report theoretical investigations on the spatial resolution of the topographic imaging of the brain activity. The head model for the theoretical study consists of five layers that imitate the scalp, skull, subarachnoid space, gray matter and white matter. The light propagation in the head model is predicted by Monte Carlo simulation to obtain the spatial sensitivity profile for a source-detector pair. The source-detector pairs are one dimensionally arranged on the surface of the model and the distance between the adjoining source-detector pairs are varied from 4 mm to 32 mm. The change in detected intensity caused by the absorption change is obtained by Monte Carlo simulation. The position of absorption change is reconstructed by the conventional mapping algorithm and the reconstruction algorithm using the spatial sensitivity profiles. We discuss the effective interval between the source-detector pairs and the choice of reconstruction algorithms to improve the topographic images of brain activity.

The Spatial and Temporal Distribution of SST in the Yellow Sea and the Evolution of the Yellow Sea Warm Current During the Holocene

NASA Astrophysics Data System (ADS)

Jia, Y.; Xiao, X.; Yu, M.; Yuan, Z. N.; Zhang, H.; Zhao, M.

2017-12-01

The Yellow Sea (YS) environment is influenced by both continental and oceanic forcing. The Yellow Sea Warm Current (YSWC) is the most significantly hydrological characteristics of the YS in winter, which is a conduit by which the deep Pacific Ocean influences the YS. Paleo-environmental records are essential for understanding the evolution of the YS environment, especially the spatial distribution of the sea surface temperature (SST) records which can be used to interpret the controlling factors of the YSWC. Previous studies mostly focused on the temporal variation but studies on both temporal and spatial environmental evolution are rather sparse. We used Uk37 temperature records in 9 cores located the north of 35°N in YS to reconstruct the spatial/temporal variations of the SST during the Holocene and further to understand the main natural factors that influenced the evolution of the YS environment and current system. All the SST records in 9 sediment cores displayed the similar trend during the Holocene, showing a regional response to marine environmental variability in the east China Seas influenced by the YSWC. To reconstruct the historical westward shift of the YSWC relative to the bathymetric trough of the YS, we compared SST records of the cores located in the west and east side of the axis of the modern YSWC. The obvious westward shift of the YSWC was observed during the periods of 4500-5000aBP, 2800-3400aBP and 1600-0aBP, especially 1000-0aBP, indicating by the distinctly gradual temperature gradients. The comparison of the East Asian Winter Monsoon(EAWM) and the Kuroshio current intensity records with the SST records revealed that the westward shift of the YSWC might be controlled by the Kuroshio intensity. Our findings have important implications for understanding the mechanisms of the variability of the YSWC.

Intensity-Duration-Frequency curves from remote sensing datasets: direct comparison of weather radar and CMORPH over the Eastern Mediterranean

NASA Astrophysics Data System (ADS)

Morin, Efrat; Marra, Francesco; Peleg, Nadav; Mei, Yiwen; Anagnostou, Emmanouil N.

2017-04-01

Rainfall frequency analysis is used to quantify the probability of occurrence of extreme rainfall and is traditionally based on rain gauge records. The limited spatial coverage of rain gauges is insufficient to sample the spatiotemporal variability of extreme rainfall and to provide the areal information required by management and design applications. Conversely, remote sensing instruments, even if quantitative uncertain, offer coverage and spatiotemporal detail that allow overcoming these issues. In recent years, remote sensing datasets began to be used for frequency analyses, taking advantage of increased record lengths and quantitative adjustments of the data. However, the studies so far made use of concepts and techniques developed for rain gauge (i.e. point or multiple-point) data and have been validated by comparison with gauge-derived analyses. These procedures add further sources of uncertainty and prevent from isolating between data and methodological uncertainties and from fully exploiting the available information. In this study, we step out of the gauge-centered concept presenting a direct comparison between at-site Intensity-Duration-Frequency (IDF) curves derived from different remote sensing datasets on corresponding spatial scales, temporal resolutions and records. We analyzed 16 years of homogeneously corrected and gauge-adjusted C-Band weather radar estimates, high-resolution CMORPH and gauge-adjusted high-resolution CMORPH over the Eastern Mediterranean. Results of this study include: (a) good spatial correlation between radar and satellite IDFs ( 0.7 for 2-5 years return period); (b) consistent correlation and dispersion in the raw and gauge adjusted CMORPH; (c) bias is almost uniform with return period for 12-24 h durations; (d) radar identifies thicker tail distributions than CMORPH and the tail of the distributions depends on the spatial and temporal scales. These results demonstrate the potential of remote sensing datasets for rainfall frequency analysis for management (e.g. warning and early-warning systems) and design (e.g. sewer design, large scale drainage planning)

A Biophysical Modeling Framework for Assessing the Environmental Impact of Biofuel Production

NASA Astrophysics Data System (ADS)

Zhang, X.; Izaurradle, C.; Manowitz, D.; West, T. O.; Post, W. M.; Thomson, A. M.; Nichols, J.; Bandaru, V.; Williams, J. R.

2009-12-01

Long-term sustainability of a biofuel economy necessitates environmentally friendly biofuel production systems. We describe a biophysical modeling framework developed to understand and quantify the environmental value and impact (e.g. water balance, nutrients balance, carbon balance, and soil quality) of different biomass cropping systems. This modeling framework consists of three major components: 1) a Geographic Information System (GIS) based data processing system, 2) a spatially-explicit biophysical modeling approach, and 3) a user friendly information distribution system. First, we developed a GIS to manage the large amount of geospatial data (e.g. climate, land use, soil, and hydrograhy) and extract input information for the biophysical model. Second, the Environmental Policy Integrated Climate (EPIC) biophysical model is used to predict the impact of various cropping systems and management intensities on productivity, water balance, and biogeochemical variables. Finally, a geo-database is developed to distribute the results of ecosystem service variables (e.g. net primary productivity, soil carbon balance, soil erosion, nitrogen and phosphorus losses, and N2O fluxes) simulated by EPIC for each spatial modeling unit online using PostgreSQL. We applied this framework in a Regional Intensive Management Area (RIMA) of 9 counties in Michigan. A total of 4,833 spatial units with relatively homogeneous biophysical properties were derived using SSURGO, Crop Data Layer, County, and 10-digit watershed boundaries. For each unit, EPIC was executed from 1980 to 2003 under 54 cropping scenarios (eg. corn, switchgrass, and hybrid poplar). The simulation results were compared with historical crop yields from USDA NASS. Spatial mapping of the results show high variability among different cropping scenarios in terms of the simulated ecosystem services variables. Overall, the framework developed in this study enables the incorporation of environmental factors into economic and life-cycle analysis in order to optimize biomass cropping production scenarios.

Partitioning the factors of spatial variation in regeneration density of shade-tolerant tree species.

PubMed

Gravel, Dominique; Beaudet, Marilou; Messier, Christian

2008-10-01

Understanding coexistence of highly shade-tolerant tree species is a longstanding challenge for forest ecologists. A conceptual model for the coexistence of sugar maple (Acer saccharum) and American beech (Fagus grandibfolia) has been proposed, based on a low-light survival/high-light growth trade-off, which interacts with soil fertility and small-scale spatiotemporal variation in the environment. In this study, we first tested whether the spatial distribution of seedlings and saplings can be predicted by the spatiotemporal variability of light availability and soil fertility, and second, the manner in which the process of environmental filtering changes with regeneration size. We evaluate the support for this hypothesis relative to the one for a neutral model, i.e., for seed rain density predicted from the distribution of adult trees. To do so, we performed intensive sampling over 86 quadrats (5 x 5 m) in a 0.24-ha plot in a mature maple-beech community in Quebec, Canada. Maple and beech abundance, soil characteristics, light availability, and growth history (used as a proxy for spatiotemporal variation in light availability) were finely measured to model variation in sapling composition across different size classes. Results indicate that the variables selected to model species distribution do effectively change with size, but not as predicted by the conceptual model. Our results show that variability in the environment is not sufficient to differentiate these species' distributions in space. Although species differ in their spatial distribution in the small size classes, they tend to correlate at the larger size class in which recruitment occurs. Overall, the results are not supportive of a model of coexistence based on small-scale variations in the environment. We propose that, at the scale of a local stand, the lack of fit of the model could result from the high similarity of species in the range of environmental conditions encountered, and we suggest that coexistence would be stable only at larger spatial scales at which variability in the environment is greater.

Contrasting spatial patterns and ecological attributes of soil bacterial and archaeal taxa across a landscape

PubMed Central

Constancias, Florentin; Saby, Nicolas P A; Terrat, Sébastien; Dequiedt, Samuel; Horrigue, Wallid; Nowak, Virginie; Guillemin, Jean-Philippe; Biju-Duval, Luc; Chemidlin Prévost-Bouré, Nicolas; Ranjard, Lionel

2015-01-01

Even though recent studies have clarified the influence and hierarchy of environmental filters on bacterial community structure, those constraining bacterial populations variations remain unclear. In consequence, our ability to understand to ecological attributes of soil bacteria and to predict microbial community response to environmental stress is therefore limited. Here, we characterized the bacterial community composition and the various bacterial taxonomic groups constituting the community across an agricultural landscape of 12 km2, by using a 215 × 215 m systematic grid representing 278 sites to precisely decipher their spatial distribution and drivers at this scale. The bacterial and Archaeal community composition was characterized by applying 16S rRNA gene pyrosequencing directly to soil DNA from samples. Geostatistics tools were used to reveal the heterogeneous distribution of bacterial composition at this scale. Soil physical parameters and land management explained a significant amount of variation, suggesting that environmental selection is the major process shaping bacterial composition. All taxa systematically displayed also a heterogeneous and particular distribution patterns. Different relative influences of soil characteristics, land use and space were observed, depending on the taxa, implying that selection and spatial processes might be differentially but not exclusively involved for each bacterial phylum. Soil pH was a major factor determining the distribution of most of the bacterial taxa and especially the most important factor explaining the spatial patterns of α-Proteobacteria and Planctomycetes. Soil texture, organic carbon content and quality were more specific to a few number of taxa (e.g., β-Proteobacteria and Chlorobi). Land management also influenced the distribution of bacterial taxa across the landscape and revealed different type of response to cropping intensity (positive, negative, neutral or hump-backed relationships) according to phyla. Altogether, this study provided valuable clues about the ecological behavior of soil bacterial and archaeal taxa at an agricultural landscape scale and could be useful for developing sustainable strategies of land management. PMID:25922908

Analysis of Spatial Distribution And Statistical Characteristics of Typhoon In The Western Pacific Based On Spatial Point Model

NASA Astrophysics Data System (ADS)

Wang, Jingmei; Gong, Adu; Li, Jing; Chen, Yanling

2017-04-01

Typhoon is a kind of strong weather system formed in tropical or subtropical oceans. China, located on the west side of the Pacific Ocean, is the country affected by the typhoon most frequently and seriously. To provide theoretical support for effectively reducing the damage caused by typhoon, the variation law of typhoon frequency is explored by analyzing the distribution of typhoon path and landing sites, sphere of influence, and the statistical characteristics of typhoon for every 5 years. In this study, the typhoon point data set was formed using the Best Path Data Set (0.1 ° × 0.1 °) compiled by China Meteorological Administration from 1950 to 2014. By using the tool of Point to Line in software ArgGIS, the typhoon paths are produced from the point data set. The influence sphere of typhoon is calculated from Euclidean distance of typhoon, whose threshold is set to 1°.The typhoon landing site was extracted by using the Chinese vector layer provided by the research group. By counting the frequency of typhoons, the landing sites, and the sphere of influence, some conclusions can be drawn as follows. In recent years, the number of typhoons generated has been reduced, typhoon intensity is relatively stable, but the impact of typhoon area has increased. Specific performance can be seen from the typhoon statistical and spatial distribution characteristics in China. In terms of frequency of typhoon landing, the number of typhoons landing in China has increased while the total number of typhoons is reduced. In terms of distribution of landing sites, the range of typhoon landing fluctuates. However, during the process of fluctuation, the range is gradually expanding. For example, in south of China, Hainan Island is affected by typhoon more frequently meanwhile China's northeast region is also gradually affected, which is extremely unusual before. Key words: spatial point model, distribution of typhoon, frequency of typhoon

Environmental determinants of the spatial distribution of Alaria alata in Hungary.

PubMed

Széll, Z; Tolnai, Z; Sréter, T

2013-11-15

Alaria alata is a potential zoonotic parasite, which is widely distributed in Eurasia. To assess the risk of human infection, it is important to know the spatial distribution pattern of the parasite and factors influencing this pattern. To investigate these relationships, 1612 red fox (Vulpes vulpes) carcasses were randomly collected from the whole Hungarian territory, and the intestines were examined by sedimentation and counting technique. The spatial distribution of the parasite was highly clumped. The topographic positions where the foxes had been shot and the intensity of infections were recorded in geographic information system database. Digitized home ranges of infected and uninfected foxes were analysed on the background of geographic vector data of altitude, land cover types, permanent waters, mean annual temperature, annual precipitation and soil permeability. Multiple regression analysis was performed with environmental parameter values and A. alata scores. Based on the statistical analysis, lack of permanent waters, mean annual temperature, annual precipitation and soil permeability were the major determinants of the spatial distribution of A. alata. It can be explained by the use of biotopes by the intermediate hosts. The lack of permanent waters results in the use of temporary waters by the second intermediate hosts, frogs. The higher temperature, the lower precipitation and the higher soil permeability lead to earlier desiccation of temporary waters, and tadpoles and frogs infected with mesocercariae can be more easily predated by the final hosts (e.g., red foxes). Moreover, temporary waters are more easily contaminated with the faeces of the final hosts containing eggs than permanent waters. Therefore, high infection rate with A. alata can be expected mainly in lowland areas, where the hydrogeography of permanent waters is less complex, the precipitation is lower, the mean temperature and the soil permeability are higher than in highland areas. Copyright © 2013 Elsevier B.V. All rights reserved.

Spatial distribution of heterocyclic organic matter compounds at macropore surfaces in Bt-horizons

NASA Astrophysics Data System (ADS)

Leue, Martin; Eckhardt, Kai-Uwe; Gerke, Horst H.; Ellerbrock, Ruth H.; Leinweber, Peter

2017-04-01

The illuvial Bt-horizon of Luvisols is characterized by coatings of clay and organic matter (OM) at the surfaces of cracks, biopores and inter-aggregate spaces. The OM composition of the coatings that originate from preferential transport of suspended matter in macropores determines the physico-chemical properties of the macropore surfaces. The analysis of the spatial distribution of specific OM components such as heterocyclic N-compounds (NCOMP) and benzonitrile and naphthalene (BN+NA) could enlighten the effect of macropore coatings on the transport of colloids and reactive solutes during preferential flow and on OM turnover processes in subsoils. The objective was to characterize the mm-to-cm scale spatial distribution of NCOMP and BN+NA at intact macropore surfaces from the Bt-horizons of two Luvisols developed on loess and glacial till. In material manually separated from macropore surfaces the proportions of NCOMP and BN+NA were determined by pyrolysis-field ionization mass spectrometry (Py-FIMS). These OM compounds, likely originating from combustion residues, were found increased in crack coatings and pinhole fillings but decreased in biopore walls (worm burrows and root channels). The Py-FIMS data were correlated with signals from C=O and C=C groups and with signals from O-H groups of clay minerals as determined by Fourier transform infrared spectroscopy in diffuse reflectance mode (DRIFT). Intensive signals of C15 to C17 alkanes from long-chain alkenes as main components of diesel and diesel exhaust particulates substantiated the assumption that burning residues were prominent in the subsoil OM. The spatial distribution of NCOMP and BN+NA along the macropores was predicted by partial least squares regression (PLSR) using DRIFT mapping spectra from intact surfaces and was found closely related to the distribution of crack coatings and pinholes. The results emphasize the importance of clay coatings in the subsoil to OM sorption and stabilization. Differences between biopores and cracks suggest differences in the mass transport and OM turnover between these macropore types in Luvisols.

Method of targeted delivery of laser beam to isolated retinal rods by fiber optics.

PubMed

Sim, Nigel; Bessarab, Dmitri; Jones, C Michael; Krivitsky, Leonid

2011-11-01

A method of controllable light delivery to retinal rod cells using an optical fiber is described. Photo-induced current of the living rod cells was measured with the suction electrode technique. The approach was tested with measurements relating the spatial distribution of the light intensity to photo-induced current. In addition, the ion current responses of rod cells to polarized light at two different orientation geometries of the cells were studied.

Spatial and temporal variations in infrared emissions of the upper atmosphere. 2. 15-μm carbon dioxide emission

NASA Astrophysics Data System (ADS)

Semenov, A. I.; Medvedeva, I. V.; Perminov, V. I.; Zheleznov, Yu. A.

2017-09-01

The results of rocket and satellite measurements of carbon dioxide emissions at a wavelength of 15 μm in the upper atmosphere have been systematized and analyzed. Analytical expressions describing the dependence of the altitude distribution of 15-μm CO2 emission intensity and its variation in the altitude range from 100 to 130 km on the season, latitude, and solar activity have been obtained.

Modified fundamental Airy wave.

PubMed

Seshadri, S R

2014-01-01

The propagation characteristics of the fundamental Airy wave are obtained; the intensity distribution is the same as that for a point electric dipole situated at the origin and oriented normal to the propagation direction. The propagation characteristics of the modified fundamental Airy wave are determined. These characteristics are the same as those for the fundamental Gaussian wave provided that an equivalent waist is identified for the Airy wave. In general, the waves are localized spatially with the peak in the propagation direction.

Relative Contribution of Matrix Structure, Patch Resources and Management to the Local Densities of Two Large Blue Butterfly Species

PubMed Central

Skórka, Piotr; Nowicki, Piotr; Bonk, Maciej; Król, Wiesław; Szpiłyk, Damian; Woyciechowski, Michal

2016-01-01

The type of matrix, the landscape surrounding habitat patches, may determine the distribution and function of local populations. However, the matrix is often heterogeneous, and its various components may differentially contribute to metapopulation processes at different spatial scales, a phenomenon that has rarely been investigated. The aim of this study was to estimate the relative importance of matrix composition and spatial scale, habitat quality, and management intensity on the occurrence and density of local populations of two endangered large blue butterflies: Phengaris teleius and P. nausithous. Presence and abundance data were assessed over two years, 2011–12, in 100 local patches within two heterogeneous regions (near Kraków and Tarnów, southern Poland). The matrix composition was analyzed at eight spatial scales. We observed high occupancy rates in both species, regions and years. With the exception of area and isolation, almost all of the matrix components contributed to Phengaris sp. densities. The different matrix components acted at different spatial scales (grassland cover within 4 and 3 km, field cover within 0.4 and 0.3 km and water cover within 4 km radii for P. teleius and P. nausithous, respectively) and provided the highest independent contribution to the butterfly densities. Additionally, the effects of a 0.4 km radius of forest cover and a food plant cover on P. teleius, and a 1 km radius of settlement cover and management intensity on P. nausithous densities were observed. Contrary to former studies we conclude that the matrix heterogeneity and spatial scale rather than general matrix type are of relevance for densities of butterflies. Conservation strategies for these umbrella species should concentrate on maintaining habitat quality and managing matrix composition at the most appropriate spatial scales. PMID:28005942

Extraction of spatial-temporal rules from mesoscale eddies in the South China Sea Based on rough set theory

NASA Astrophysics Data System (ADS)

Du, Y.; Fan, X.; He, Z.; Su, F.; Zhou, C.; Mao, H.; Wang, D.

2011-06-01

In this paper, a rough set theory is introduced to represent spatial-temporal relationships and extract the corresponding rules from typical mesoscale-eddy states in the South China Sea (SCS). Three decision attributes are adopted in this study, which make the approach flexible in retrieving spatial-temporal rules with different features. Spatial-temporal rules of typical states in the SCS are extracted as three decision attributes, which then are confirmed by the previous works. The results demonstrate that this approach is effective in extracting spatial-temporal rules from typical mesoscale-eddy states, and therefore provides a powerful approach to forecasts in the future. Spatial-temporal rules in the SCS indicate that warm eddies following the rules are generally in the southeastern and central SCS around 2000 m isobaths in winter. Their intensity and vorticity are weaker than those of cold eddies. They usually move a shorter distance. By contrast, cold eddies are in 2000 m-deeper regions of the southwestern and northeastern SCS in spring and fall. Their intensity and vorticity are strong. Usually they move a long distance. In winter, a few rules are followed by cold eddies in the northern tip of the basin and southwest of Taiwan Island rather than warm eddies, indicating cold eddies may be well-regulated in the region. Several warm-eddy rules are achieved west of Luzon Island, indicating warm eddies may be well-regulated in the region as well. Otherwise, warm and cold eddies are distributed not only in the jet flow off southern Vietnam induced by intraseasonal wind stress in summer-fall, but also in the northern shallow water, which should be a focus of future study.

Relative Contribution of Matrix Structure, Patch Resources and Management to the Local Densities of Two Large Blue Butterfly Species.

PubMed

Kajzer-Bonk, Joanna; Skórka, Piotr; Nowicki, Piotr; Bonk, Maciej; Król, Wiesław; Szpiłyk, Damian; Woyciechowski, Michal

2016-01-01

The type of matrix, the landscape surrounding habitat patches, may determine the distribution and function of local populations. However, the matrix is often heterogeneous, and its various components may differentially contribute to metapopulation processes at different spatial scales, a phenomenon that has rarely been investigated. The aim of this study was to estimate the relative importance of matrix composition and spatial scale, habitat quality, and management intensity on the occurrence and density of local populations of two endangered large blue butterflies: Phengaris teleius and P. nausithous. Presence and abundance data were assessed over two years, 2011-12, in 100 local patches within two heterogeneous regions (near Kraków and Tarnów, southern Poland). The matrix composition was analyzed at eight spatial scales. We observed high occupancy rates in both species, regions and years. With the exception of area and isolation, almost all of the matrix components contributed to Phengaris sp. densities. The different matrix components acted at different spatial scales (grassland cover within 4 and 3 km, field cover within 0.4 and 0.3 km and water cover within 4 km radii for P. teleius and P. nausithous, respectively) and provided the highest independent contribution to the butterfly densities. Additionally, the effects of a 0.4 km radius of forest cover and a food plant cover on P. teleius, and a 1 km radius of settlement cover and management intensity on P. nausithous densities were observed. Contrary to former studies we conclude that the matrix heterogeneity and spatial scale rather than general matrix type are of relevance for densities of butterflies. Conservation strategies for these umbrella species should concentrate on maintaining habitat quality and managing matrix composition at the most appropriate spatial scales.

Transient deterministic shallow landslide modeling: Requirements for susceptibility and hazard assessments in a GIS framework

USGS Publications Warehouse

Godt, J.W.; Baum, R.L.; Savage, W.Z.; Salciarini, D.; Schulz, W.H.; Harp, E.L.

2008-01-01

Application of transient deterministic shallow landslide models over broad regions for hazard and susceptibility assessments requires information on rainfall, topography and the distribution and properties of hillside materials. We survey techniques for generating the spatial and temporal input data for such models and present an example using a transient deterministic model that combines an analytic solution to assess the pore-pressure response to rainfall infiltration with an infinite-slope stability calculation. Pore-pressures and factors of safety are computed on a cell-by-cell basis and can be displayed or manipulated in a grid-based GIS. Input data are high-resolution (1.8??m) topographic information derived from LiDAR data and simple descriptions of initial pore-pressure distribution and boundary conditions for a study area north of Seattle, Washington. Rainfall information is taken from a previously defined empirical rainfall intensity-duration threshold and material strength and hydraulic properties were measured both in the field and laboratory. Results are tested by comparison with a shallow landslide inventory. Comparison of results with those from static infinite-slope stability analyses assuming fixed water-table heights shows that the spatial prediction of shallow landslide susceptibility is improved using the transient analyses; moreover, results can be depicted in terms of the rainfall intensity and duration known to trigger shallow landslides in the study area.

MRI intensity nonuniformity correction using simultaneously spatial and gray-level histogram information.

PubMed

Milles, Julien; Zhu, Yue Min; Gimenez, Gérard; Guttmann, Charles R G; Magnin, Isabelle E

2007-03-01

A novel approach for correcting intensity nonuniformity in magnetic resonance imaging (MRI) is presented. This approach is based on the simultaneous use of spatial and gray-level histogram information. Spatial information about intensity nonuniformity is obtained using cubic B-spline smoothing. Gray-level histogram information of the image corrupted by intensity nonuniformity is exploited from a frequential point of view. The proposed correction method is illustrated using both physical phantom and human brain images. The results are consistent with theoretical prediction, and demonstrate a new way of dealing with intensity nonuniformity problems. They are all the more significant as the ground truth on intensity nonuniformity is unknown in clinical images.

Effect of precursor solutions stirring on deep level defects concentration and spatial distribution in low temperature aqueous chemical synthesis of zinc oxide nanorods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Alnoor, Hatim, E-mail: hatim.alnoor@liu.se; Chey, Chan Oeurn; Pozina, Galia

Hexagonal c-axis oriented zinc oxide (ZnO) nanorods (NRs) with 120-300 nm diameters are synthesized via the low temperature aqueous chemical route at 80 °C on silver-coated glass substrates. The influence of varying the precursor solutions stirring durations on the concentration and spatial distributions of deep level defects in ZnO NRs is investigated. Room temperature micro-photoluminesnce (μ-PL) spectra were collected for all samples. Cathodoluminescence (CL) spectra of the as-synthesized NRs reveal a significant change in the intensity ratio of the near band edge emission (NBE) to the deep-level emission (DLE) peaks with increasing stirring durations. This is attributed to the variation inmore » the concentration of the oxygen-deficiency with increasing stirring durations as suggested from the X-ray photoelectron spectroscopy analysis. Spatially resolved CL spectra taken along individual NRs revealed that stirring the precursor solutions for relatively short duration (1-3 h), which likely induced high super saturation under thermodynamic equilibrium during the synthesis process, is observed to favor the formation of point defects moving towards the tip of the NRs. In contrary, stirring for longer duration (5-15 h) will induce low super saturation favoring the formation of point defects located at the bottom of the NRs. These findings demonstrate that it is possible to control the concentration and spatial distribution of deep level defects in ZnO NRs by varying the stirring durations of the precursor solutions.« less

Detection of forest stand-level spatial structure in ectomycorrhizal fungal communities.

PubMed

Lilleskov, Erik A; Bruns, Thomas D; Horton, Thomas R; Taylor, D; Grogan, Paul

2004-08-01

Ectomycorrhizal fungal (EMF) communities are highly diverse at the stand level. To begin to understand what might lead to such diversity, and to improve sampling designs, we investigated the spatial structure of these communities. We used EMF community data from a number of studies carried out in seven mature and one recently fire-initiated forest stand. We applied various measures of spatial pattern to characterize distributions at EMF community and species levels: Mantel tests, Mantel correlograms, variance/mean and standardized variograms. Mantel tests indicated that in four of eight sites community similarity decreased with distance, whereas Mantel correlograms also found spatial autocorrelation in those four plus two additional sites. In all but one of these sites elevated similarity was evident only at relatively small spatial scales (< 2.6 m), whereas one exhibited a larger scale pattern ( approximately 25 m). Evenness of biomass distribution among cores varied widely among taxa. Standardized variograms indicated that most of the dominant taxa showed patchiness at a scale of less than 3 m, with a range from 0 to < or =17 m. These results have implications for both sampling scale and intensity to achieve maximum efficiency of community sampling. In the systems we examined, cores should be at least 3 m apart to achieve the greatest sampling efficiency for stand-level community analysis. In some cases even this spacing may result in reduced sampling efficiency arising from patterns of spatial autocorrelation. Interpretation of the causes and significance of these patterns requires information on the genetic identity of individuals in the communities.

An application to model traffic intensity of agricultural machinery at field scale

NASA Astrophysics Data System (ADS)

Augustin, Katja; Kuhwald, Michael; Duttmann, Rainer

2017-04-01

Several soil-pressure-models deal with the impact of agricultural machines on soils. In many cases, these models were used for single spots and consider a static machine configuration. Therefore, a statement about the spatial distribution of soil compaction risk for entire working processes is limited. The aim of the study is the development of an application for the spatial modelling of traffic lanes from agricultural vehicles including wheel load, ground pressure and wheel passages at the field scale. The application is based on Open Source software, application and data formats, using python programming language. Minimum input parameters are GPS-positions, vehicles and tires (producer and model) and the tire inflation pressure. Five working processes were distinguished: soil tillage, manuring, plant protection, sowing and harvest. Currently, two different models (Diserens 2009, Rücknagel et al. 2015) were implemented to calculate the soil pressure. The application was tested at a study site in Lower Saxony, Germany. Since 2015, field traffic were recorded by RTK-GPS and used machine set ups were noted. Using these input information the traffic lanes, wheel load and soil pressure were calculated for all working processes. For instance, the maize harvest in 2016 with a crop chopper and one transport vehicle crossed about 55 % of the total field area. At some places the machines rolled over up to 46 times. Approximately 35 % of the total area was affected by wheel loads over 7 tons and soil pressures between 163 and 193 kPa. With the information about the spatial distribution of wheel passages, wheel load and soil pressure it is possible to identify hot spots of intensive field traffic. Additionally, the use of the application enables the analysis of soil compaction risk induced by agricultural machines for long- and short-term periods.

Flood and Landslide Applications of High Time Resolution Satellite Rain Products

NASA Technical Reports Server (NTRS)

Adler, Robert F.; Hong, Yang; Huffman, George J.

2006-01-01

Experimental, potentially real-time systems to detect floods and landslides related to heavy rain events are described. A key basis for these applications is high time resolution satellite rainfall analyses. Rainfall is the primary cause for devastating floods across the world. However, in many countries, satellite-based precipitation estimation may be the best source of rainfall data due to insufficient ground networks and absence of data sharing along many trans-boundary river basins. Remotely sensed precipitation from the NASA's TRMM Multi-satellite Precipitation Analysis (TMPA) operational system (near real-time precipitation at a spatial-temporal resolution of 3 hours and 0.25deg x 0.25deg) is used to monitor extreme precipitation events. Then these data are ingested into a macro-scale hydrological model which is parameterized using spatially distributed elevation, soil and land cover datasets available globally from satellite remote sensing. Preliminary flood results appear reasonable in terms of location and frequency of events, with implementation on a quasi-global basis underway. With the availability of satellite rainfall analyses at fine time resolution, it has also become possible to assess landslide risk on a near-global basis. Early results show that landslide occurrence is closely associated with the spatial patterns and temporal distribution of TRMM rainfall characteristics. Particularly, the number of landslides triggered by rainfall is related to rainfall climatology, antecedent rainfall accumulation, and intensity-duration of rainstorms. For the purpose of prediction, an empirical TMPA-based rainfall intensity-duration threshold is developed and shown to have skill in determining potential areas of landslides. These experimental findings, in combination with landslide surface susceptibility information based on satellite-based land surface information, form a starting point towards a potential operational landslide monitoring/warning system around the globe.

Monitoring proteins using in vivo near-infrared time-domain optical imaging after 2-O-hexyldiglycerol-mediated transfer to the brain.

PubMed

Hülper, Petra; Dullin, Christian; Kugler, Wilfried; Lakomek, Max; Erdlenbruch, Bernhard

2011-04-01

The aim of the present study was to gain insight into the penetration, biodistribution, and fate of globulins in the brain after 2-O-hexyldiglycerol-induced blood-brain barrier opening. The spatial distribution of fluorescence probes was investigated after blood-brain barrier opening with intracarotid 2-O-hexyldiglycerol injection. Fluorescence intensity was visualized by microscopy (mice and rats) and by in vivo time-domain optical imaging. There was an increased 2-O-hexyldiglycerol-mediated transfer of fluorescence-labeled globulins into the ipsilateral hemisphere. Sequential in vivo measurements revealed that the increase in protein concentration lasted at least 96 h after administration. Ex vivo detection of tissue fluorescence confirmed the results obtained in vivo. Globulins enter the healthy brain in conjunction with 2-O-hexyldiglycerol. Sequential in vivo near-infrared fluorescence measurements enable the visualization of the spatial distribution of antibodies in the brain of living small animals.

[Heat island effect and human body comfortable degree in Zhengzhou city].

PubMed

Zheng, Jinggang; Zhang, Jingguang; Li, You

2005-10-01

In this paper, the key factors of heat island effect in Zhengzhou city were monitored by grid method to study the diurnal and seasonal changes and the spatial distribution of the effect, and to evaluate the comfortable degree of human bodies at different sites of the city. The results showed that on the whole, the heat island effect had a unimodal diurnal change, while its intensity was distinctly different among seasons, being decreased in order of winter > spring > autumn > summer. The spatial distribution of heat island center was significantly related to its nearby industrial heat resources. As for the comfortable degree of human bodies, the People's Park was the best site because of its arbor virescence, while in the Xiliu Lake Park with lawn as its main greening type, its capability of improving microclimate was weaker. The railway station square still had 16% frequency of most comfortable degree, because of its open space and better air fluidity.

Classification of Earthquake-triggered Landslide Events - Review of Classical and Particular Cases

NASA Astrophysics Data System (ADS)

Braun, A.; Havenith, H. B.; Schlögel, R.

2016-12-01

Seismically induced landslides often contribute to a significant degree to the losses related to earthquakes. The identification of possible extends of landslide affected areas can help to target emergency measures when an earthquake occurs or improve the resilience of inhabited areas and critical infrastructure in zones of high seismic hazard. Moreover, landslide event sizes are an important proxy for the estimation of the intensity and magnitude of past earthquakes in paleoseismic studies, allowing us to improve seismic hazard assessment over longer terms. Not only earthquake intensity, but also factors such as the fault characteristics, topography, climatic conditions and the geological environment have a major impact on the intensity and spatial distribution of earthquake induced landslides. Inspired by classical reviews of earthquake induced landslides, e.g. by Keefer or Jibson, we present here a review of factors contributing to earthquake triggered slope failures based on an `event-by-event' classification approach. The objective of this analysis is to enable the short-term prediction of earthquake triggered landslide event sizes in terms of numbers and size of the affected area right after an earthquake event occurred. Five main factors, `Intensity', `Fault', `Topographic energy', `Climatic conditions' and `Surface geology' were used to establish a relationship to the number and spatial extend of landslides triggered by an earthquake. Based on well-documented recent earthquakes (e.g. Haiti 2010, Wenchuan 2008) and on older events for which reliable extensive information was available (e.g. Northridge 1994, Loma Prieta 1989, Guatemala 1976, Peru 1970) the combination and relative weight of the factors was calibrated. The calibrated factor combination was then applied to more than 20 earthquake events for which landslide distribution characteristics could be crosschecked. We present cases where our prediction model performs well and discuss particular cases where it does not. These are e.g. cases of far distant, delayed or ancient earthquake induced landslides.

A Probabilistic Analysis of Surface Water Flood Risk in London.

PubMed

Jenkins, Katie; Hall, Jim; Glenis, Vassilis; Kilsby, Chris

2018-06-01

Flooding in urban areas during heavy rainfall, often characterized by short duration and high-intensity events, is known as "surface water flooding." Analyzing surface water flood risk is complex as it requires understanding of biophysical and human factors, such as the localized scale and nature of heavy precipitation events, characteristics of the urban area affected (including detailed topography and drainage networks), and the spatial distribution of economic and social vulnerability. Climate change is recognized as having the potential to enhance the intensity and frequency of heavy rainfall events. This study develops a methodology to link high spatial resolution probabilistic projections of hourly precipitation with detailed surface water flood depth maps and characterization of urban vulnerability to estimate surface water flood risk. It incorporates probabilistic information on the range of uncertainties in future precipitation in a changing climate. The method is applied to a case study of Greater London and highlights that both the frequency and spatial extent of surface water flood events are set to increase under future climate change. The expected annual damage from surface water flooding is estimated to be to be £171 million, £343 million, and £390 million/year under the baseline, 2030 high, and 2050 high climate change scenarios, respectively. © 2017 Society for Risk Analysis.

Integrating population dynamics into mapping human exposure to seismic hazard

NASA Astrophysics Data System (ADS)

Freire, S.; Aubrecht, C.

2012-11-01

Disaster risk is not fully characterized without taking into account vulnerability and population exposure. Assessment of earthquake risk in urban areas would benefit from considering the variation of population distribution at more detailed spatial and temporal scales, and from a more explicit integration of this improved demographic data with existing seismic hazard maps. In the present work, "intelligent" dasymetric mapping is used to model population dynamics at high spatial resolution in order to benefit the analysis of spatio-temporal exposure to earthquake hazard in a metropolitan area. These night- and daytime-specific population densities are then classified and combined with seismic intensity levels to derive new spatially-explicit four-class-composite maps of human exposure. The presented approach enables a more thorough assessment of population exposure to earthquake hazard. Results show that there are significantly more people potentially at risk in the daytime period, demonstrating the shifting nature of population exposure in the daily cycle and the need to move beyond conventional residence-based demographic data sources to improve risk analyses. The proposed fine-scale maps of human exposure to seismic intensity are mainly aimed at benefiting visualization and communication of earthquake risk, but can be valuable in all phases of the disaster management process where knowledge of population densities is relevant for decision-making.

Geometry and scaling laws of excursion and iso-sets of enstrophy and dissipation in isotropic turbulence

NASA Astrophysics Data System (ADS)

Elsas, José Hugo; Szalay, Alexander S.; Meneveau, Charles

2018-04-01

Motivated by interest in the geometry of high intensity events of turbulent flows, we examine the spatial correlation functions of sets where turbulent events are particularly intense. These sets are defined using indicator functions on excursion and iso-value sets. Their geometric scaling properties are analysed by examining possible power-law decay of their radial correlation function. We apply the analysis to enstrophy, dissipation and velocity gradient invariants Q and R and their joint spatial distributions, using data from a direct numerical simulation of isotropic turbulence at Reλ ≈ 430. While no fractal scaling is found in the inertial range using box-counting in the finite Reynolds number flow considered here, power-law scaling in the inertial range is found in the radial correlation functions. Thus, a geometric characterisation in terms of these sets' correlation dimension is possible. Strong dependence on the enstrophy and dissipation threshold is found, consistent with multifractal behaviour. Nevertheless, the lack of scaling of the box-counting analysis precludes direct quantitative comparisons with earlier work based on multifractal formalism. Surprising trends, such as a lower correlation dimension for strong dissipation events compared to strong enstrophy events, are observed and interpreted in terms of spatial coherence of vortices in the flow.

GIS and agent based spatial-temporal simulation modeling for assessing tourism social carrying capacity: a study on Mount Emei scenic area, China

NASA Astrophysics Data System (ADS)

Zhang, Renjun

2007-06-01

Each scenic area can sustain a specific level of acceptance of tourist development and use, beyond which further development can result in socio-cultural deterioration or a decline in the quality of the experience gained by visitors. This specific level is called carrying capacity. Social carrying capacity can be defined as the maximum level of use (in terms of numbers and activities) that can be absorbed by an area without an unacceptable decline in the quality of experience of visitors and without an unacceptable adverse impact on the society of the area. It is difficult to assess the carrying capacity, because the carrying capacity is determined by not only the number of visitors, but also the time, the type of the recreation, the characters of each individual and the physical environment. The objective of this study is to build a spatial-temporal simulation model to simulate the spatial-temporal distribution of tourists. This model is a tourist spatial behaviors simulator (TSBS). Based on TSBS, the changes of each visitor's travel patterns such as location, cost, and other states data are recoded in a state table. By analyzing this table, the intensity of the tourist use in any area can be calculated; the changes of the quality of tourism experience can be quantized and analyzed. So based on this micro simulation method the social carrying capacity can be assessed more accurately, can be monitored proactively and managed adaptively. In this paper, the carrying capacity of Mount Emei scenic area is analyzed as followed: The author selected the intensity of the crowd as the monitoring Indicators. it is regarded that longer waiting time means more crowded. TSBS was used to simulate the spatial-temporal distribution of tourists. the average of waiting time all the visitors is calculated. And then the author assessed the social carrying capacity of Mount Emei scenic area, found the key factors have impacted on social carrying capacity. The results show that the TSBS-aided method for assessing carrying capacity is dynamic, quantifiable and more accurate.

[Spatial distribution pattern and fractal analysis of Larix chinensis populations in Qinling Mountain].

PubMed

Guo, Hua; Wang, Xiaoan; Xiao, Yaping

2005-02-01

In this paper, the fractal characters of Larix chinensis populations in Qinling Mountain were studied by contiguous grid quadrate sampling method and by boxing-counting dimension and information dimension. The results showed that the high boxing-counting dimension (1.8087) and information dimension (1.7931) reflected a higher spatial occupational degree of L. chinensis populations. Judged by the dispersal index and Morisita's pattern index, L. chinensis populations clumped at three different age stages (0-25, 25-50 and over 50 years). From Greig-Smiths' mean variance analysis, the figure of pattern scale showed that L. chinensis populations clumped in 128 m2 and 512 m2, and the different age groups clumped in different scales. The pattern intensities decreased with increasing age, and tended to reduce with increasing area when detected by Kershaw's PI index. The spatial pattern characters of L. chinensis populations may be their responses to environmental factors.

Electrically and spatially controllable PDLC phase gratings for diffraction and modulation of laser beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hadjichristov, Georgi B., E-mail: georgibh@issp.bas.bg; Marinov, Yordan G.; Petrov, Alexander G.

2016-03-25

We present a study on electrically- and spatially-controllable laser beam diffraction, electrooptic (EO) phase modulation, as well as amplitude-frequency EO modulation by single-layer microscale polymer-dispersed liquid crystal (PDLC) phase gratings (PDLC SLPGs) of interest for device applications. PDLC SLPGs were produced from nematic liquid crystal (LC) E7 in photo-curable NOA65 polymer. The wedge-formed PDLC SLPGs have a continuously variable thickness (2–25 µm). They contain LC droplets of diameters twice as the layer thickness, with a linear-gradient size distribution along the wedge. By applying alternating-current (AC) electric field, the PDLC SLPGs produce efficient: (i) diffraction splitting of transmitted laser beams; (ii)more » spatial redistribution of diffracted light intensity; (iii) optical phase modulation; (iv) amplitude-frequency modulation, all controllable by the driven AC field and the droplet size gradient.« less

Spatial and temporal variability of microgeographic genetic structure in white-tailed deer

USGS Publications Warehouse

Scribner, Kim T.; Smith, Michael H.; Chesser, Ronald K.

1997-01-01

Techniques are described that define contiguous genetic subpopulations of white-tailed deer (Odocoileus virginianus) based on the spatial dispersion of 4,749 individuals that possessed discrete character values (alleles or genotypes) during each of 6 years (1974-1979). White-tailed deer were not uniformly distributed in space, but exhibited considerable spatial genetic structuring. Significant non-random clusters of individuals were documented during each year based on specific alleles and genotypes at the Sdh locus. Considerable temporal variation was observed in the position and genetic composition of specific clusters, which reflected changes in allele frequency in small geographic areas. The position of clusters did not consistently correspond with traditional management boundaries based on major discontinuities in habitat (swamp versus upland) and hunt compartments that were defined by roads and streams. Spatio-temporal stability of observed genetic contiguous clusters was interpreted relative to method and intensity of harvest, movements, and breeding ecology.

Study of Earthquake Disaster Prediction System of Langfang city Based on GIS

NASA Astrophysics Data System (ADS)

Huang, Meng; Zhang, Dian; Li, Pan; Zhang, YunHui; Zhang, RuoFei

2017-07-01

In this paper, according to the status of China’s need to improve the ability of earthquake disaster prevention, this paper puts forward the implementation plan of earthquake disaster prediction system of Langfang city based on GIS. Based on the GIS spatial database, coordinate transformation technology, GIS spatial analysis technology and PHP development technology, the seismic damage factor algorithm is used to predict the damage of the city under different intensity earthquake disaster conditions. The earthquake disaster prediction system of Langfang city is based on the B / S system architecture. Degree and spatial distribution and two-dimensional visualization display, comprehensive query analysis and efficient auxiliary decision-making function to determine the weak earthquake in the city and rapid warning. The system has realized the transformation of the city’s earthquake disaster reduction work from static planning to dynamic management, and improved the city’s earthquake and disaster prevention capability.

Single laser beam of spatial coherence from an array of GaAs lasers - Free-running mode

NASA Technical Reports Server (NTRS)

Philipp-Rutz, E. M.

1975-01-01

Spatially coherent radiation from a monolithic array of three GaAs lasers in a free-running mode is reported. The lasers, with their mirror faces antireflection coated, are operated in an external optical cavity built of spherical lenses and plane mirrors. The spatially coherent-beam formation makes use of the Fourier-transformation property of the internal lenses. Transverse mode control is accomplished by a spatial filter. The optical cavity is similar to that used for the phase-controlled mode of spatially coherent-beam formation; only the spatial filters are different. In the far field (when restored by an external lens), the intensities of the lasers in the array are concentrated in a single laser beam of spatial coherence, without any grating lobes. The far-field distribution of the laser array in the free-running mode differs significantly from the interference pattern of the phase-controlled mode. The modulation characteristics of the optical waveforms of the two modes are also quite different because modulation is related to the interaction of the spatial filter with the longitudinal modes of the laser array within the optical cavity. The modulation of the optical waveform of the free-running mode is nonperiodic, confirming that the fluctuations of the optical fields of the lasers are random.

Characteristics of VLF wave propagation in the Earth's magnetosphere in the presence of an artificial density duct

NASA Astrophysics Data System (ADS)

Pasmanik, Dmitry; Demekhov, Andrei

We study the propagation of VLF waves in the Earth's ionosphere and magnetosphere in the presence of large-scale artificial plasma inhomogeneities which can be created by HF heating facilities like HAARP and ``Sura''. A region with enhanced cold plasma density can be formed due to the action of HF heating. This region is extended along geomagnetic field (up to altitudes of several thousand km) and has rather small size across magnetic field (about 1 degree). The geometric-optical approximation is used to study wave propagation. The plasma density and ion composition are calculated with the use of SAMI2 model, which was modified to take the effect of HF heating into account. We calculate ray trajectories of waves with different initial frequency and wave-normal angles and originating at altitudes of about 100 km in the region near the heating area. The source of such waves could be the lightning discharges, modulated HF heating of the ionosphere, or VLF transmitters. Variation of the wave amplitude along the ray trajectories due to refraction is considered and spatial distribution of wave intensity in the magnetosphere is analyzed. We show that the presence of such a density disturbances can lead to significant changes of wave propagation trajectories, in particular, to efficient guiding of VLF waves in this region. This can result in a drastic increase of the VLF-wave intensity in the density duct. The dependence of wave propagation properties on parameters of heating facility operation regime is considered. We study the variation of the spatial distribution of VLF wave intensity related to the slow evolution of the artificial inhomogeneity during the heating.

A quick earthquake disaster loss assessment method supported by dasymetric data for emergency response in China

NASA Astrophysics Data System (ADS)

Xu, Jinghai; An, Jiwen; Nie, Gaozong

2016-04-01

Improving earthquake disaster loss estimation speed and accuracy is one of the key factors in effective earthquake response and rescue. The presentation of exposure data by applying a dasymetric map approach has good potential for addressing this issue. With the support of 30'' × 30'' areal exposure data (population and building data in China), this paper presents a new earthquake disaster loss estimation method for emergency response situations. This method has two phases: a pre-earthquake phase and a co-earthquake phase. In the pre-earthquake phase, we pre-calculate the earthquake loss related to different seismic intensities and store them in a 30'' × 30'' grid format, which has several stages: determining the earthquake loss calculation factor, gridding damage probability matrices, calculating building damage and calculating human losses. Then, in the co-earthquake phase, there are two stages of estimating loss: generating a theoretical isoseismal map to depict the spatial distribution of the seismic intensity field; then, using the seismic intensity field to extract statistics of losses from the pre-calculated estimation data. Thus, the final loss estimation results are obtained. The method is validated by four actual earthquakes that occurred in China. The method not only significantly improves the speed and accuracy of loss estimation but also provides the spatial distribution of the losses, which will be effective in aiding earthquake emergency response and rescue. Additionally, related pre-calculated earthquake loss estimation data in China could serve to provide disaster risk analysis before earthquakes occur. Currently, the pre-calculated loss estimation data and the two-phase estimation method are used by the China Earthquake Administration.

Supervised variational model with statistical inference and its application in medical image segmentation.

PubMed

Li, Changyang; Wang, Xiuying; Eberl, Stefan; Fulham, Michael; Yin, Yong; Dagan Feng, David

2015-01-01

Automated and general medical image segmentation can be challenging because the foreground and the background may have complicated and overlapping density distributions in medical imaging. Conventional region-based level set algorithms often assume piecewise constant or piecewise smooth for segments, which are implausible for general medical image segmentation. Furthermore, low contrast and noise make identification of the boundaries between foreground and background difficult for edge-based level set algorithms. Thus, to address these problems, we suggest a supervised variational level set segmentation model to harness the statistical region energy functional with a weighted probability approximation. Our approach models the region density distributions by using the mixture-of-mixtures Gaussian model to better approximate real intensity distributions and distinguish statistical intensity differences between foreground and background. The region-based statistical model in our algorithm can intuitively provide better performance on noisy images. We constructed a weighted probability map on graphs to incorporate spatial indications from user input with a contextual constraint based on the minimization of contextual graphs energy functional. We measured the performance of our approach on ten noisy synthetic images and 58 medical datasets with heterogeneous intensities and ill-defined boundaries and compared our technique to the Chan-Vese region-based level set model, the geodesic active contour model with distance regularization, and the random walker model. Our method consistently achieved the highest Dice similarity coefficient when compared to the other methods.

Downscaling Satellite Precipitation with Emphasis on Extremes: A Variational ℓ1-Norm Regularization in the Derivative Domain

NASA Astrophysics Data System (ADS)

Foufoula-Georgiou, E.; Ebtehaj, A. M.; Zhang, S. Q.; Hou, A. Y.

2014-05-01

The increasing availability of precipitation observations from space, e.g., from the Tropical Rainfall Measuring Mission (TRMM) and the forthcoming Global Precipitation Measuring (GPM) Mission, has fueled renewed interest in developing frameworks for downscaling and multi-sensor data fusion that can handle large data sets in computationally efficient ways while optimally reproducing desired properties of the underlying rainfall fields. Of special interest is the reproduction of extreme precipitation intensities and gradients, as these are directly relevant to hazard prediction. In this paper, we present a new formalism for downscaling satellite precipitation observations, which explicitly allows for the preservation of some key geometrical and statistical properties of spatial precipitation. These include sharp intensity gradients (due to high-intensity regions embedded within lower-intensity areas), coherent spatial structures (due to regions of slowly varying rainfall), and thicker-than-Gaussian tails of precipitation gradients and intensities. Specifically, we pose the downscaling problem as a discrete inverse problem and solve it via a regularized variational approach (variational downscaling) where the regularization term is selected to impose the desired smoothness in the solution while allowing for some steep gradients (called ℓ1-norm or total variation regularization). We demonstrate the duality between this geometrically inspired solution and its Bayesian statistical interpretation, which is equivalent to assuming a Laplace prior distribution for the precipitation intensities in the derivative (wavelet) space. When the observation operator is not known, we discuss the effect of its misspecification and explore a previously proposed dictionary-based sparse inverse downscaling methodology to indirectly learn the observation operator from a data base of coincidental high- and low-resolution observations. The proposed method and ideas are illustrated in case studies featuring the downscaling of a hurricane precipitation field.

Downscaling Satellite Precipitation with Emphasis on Extremes: A Variational 1-Norm Regularization in the Derivative Domain

NASA Technical Reports Server (NTRS)

Foufoula-Georgiou, E.; Ebtehaj, A. M.; Zhang, S. Q.; Hou, A. Y.

2013-01-01

The increasing availability of precipitation observations from space, e.g., from the Tropical Rainfall Measuring Mission (TRMM) and the forthcoming Global Precipitation Measuring (GPM) Mission, has fueled renewed interest in developing frameworks for downscaling and multi-sensor data fusion that can handle large data sets in computationally efficient ways while optimally reproducing desired properties of the underlying rainfall fields. Of special interest is the reproduction of extreme precipitation intensities and gradients, as these are directly relevant to hazard prediction. In this paper, we present a new formalism for downscaling satellite precipitation observations, which explicitly allows for the preservation of some key geometrical and statistical properties of spatial precipitation. These include sharp intensity gradients (due to high-intensity regions embedded within lower-intensity areas), coherent spatial structures (due to regions of slowly varying rainfall),and thicker-than-Gaussian tails of precipitation gradients and intensities. Specifically, we pose the downscaling problem as a discrete inverse problem and solve it via a regularized variational approach (variational downscaling) where the regularization term is selected to impose the desired smoothness in the solution while allowing for some steep gradients(called 1-norm or total variation regularization). We demonstrate the duality between this geometrically inspired solution and its Bayesian statistical interpretation, which is equivalent to assuming a Laplace prior distribution for the precipitation intensities in the derivative (wavelet) space. When the observation operator is not known, we discuss the effect of its misspecification and explore a previously proposed dictionary-based sparse inverse downscaling methodology to indirectly learn the observation operator from a database of coincidental high- and low-resolution observations. The proposed method and ideas are illustrated in case studies featuring the downscaling of a hurricane precipitation field.

Simulations and measurements of hot-electron generation driven by the multibeam two-plasmon-decay instability

NASA Astrophysics Data System (ADS)

Follett, R. K.; Myatt, J. F.; Shaw, J. G.; Michel, D. T.; Solodov, A. A.; Edgell, D. H.; Yaakobi, B.; Froula, D. H.

2017-10-01

Multibeam experiments relevant to direct-drive inertial confinement fusion show the importance of nonlinear saturation mechanisms in the common-wave two-plasmon-decay (TPD) instability. Planar-target experiments on the OMEGA laser used hard x-ray measurements to study the influence of the linear common-wave growth rate on TPD-driven hot-electron production in two drive-beam configurations and over a range of overlapped laser intensities from 3.6 to 15.2 × 1014 W/cm2. The beam configuration with the larger linear common-wave growth rate had a lower intensity threshold for the onset of hot-electron production, but the linear growth rate made no significant impact on hot-electron production at high intensities. The experiments were modeled in 3-D using a hybrid code LPSE (laser plasma simulation environment) that combines a wave solver with a particle tracker to self-consistently calculate the electron velocity distribution and evolve electron Landau damping. Good quantitative agreement was obtained between the simulated and measured hot-electron distributions using a novel technique to account for macroscopic spatial and temporal variations that were present in the experiments.

Simulations and measurements of hot-electron generation driven by the multibeam two-plasmon-decay instability

DOE PAGES

Follett, R. K.; Myatt, J. F.; Shaw, J. G.; ...

2017-10-30

We report that multiple-beam experiments relevant to direct-drive inertial confinement fusion show the importance of nonlinear saturation mechanisms in the common-wave two-plasmon-decay (TPD) instability. Planar target experiments on the OMEGA laser used hard-x-ray measurements to study the influence of the linear common-wave growth rate on TPD driven hot-electron production in two drive beam configurations and over a range of overlapped laser intensities from 3.6 to 15.2 x 10 14 W/cm 2. The beam configuration with the larger linear common-wave growth rate had a lower intensity threshold for the onset of hot-electron production, but the linear growth rate did not havemore » a significant impact on hot-electron production at high intensities. The experiments were modeled in 3-D using a hybrid code (LPSE) that combines a wave solver with a particle tracker to self-consistently calculate the electron velocity distribution and evolve electron Landau damping. Finally, good quantitative agreement was obtained between the simulated and measured hotel-electron distributions using a novel technique to account for macroscopic spatial and temporal variations that are present in the experiments.« less

Absolute Soft X-ray Emission Measurements at the Nike Laser

NASA Astrophysics Data System (ADS)

Weaver, J.; Atkin, R.; Boyer, C.; Colombant, D.; Feldman, U.; Fielding, D.; Gardner, J.; Holland, G.; Klapisch, M.; Mostovych, A. N.; Obenscain, S.; Seely, J. F.

2002-11-01

Recent experiments at the Nike laser facility have demonstrated that, when a low intensity prepulse ( 2main laser intensity) is used to heat a thin Au or Pd coating on a planar CH target, the growth of non-uniformities due to laser imprint can be reduced from the growth observed for an uncoated CH target. The absolute radiation intensity in the soft x-ray region (0.1-1 keV) has a important role in the energy balance for layered targets. There is an ongoing effort to characterize the soft x-ray emission using an absolutely calibrated transmission grating spectrometer and filtered diode modules. Measurements of the angular distribution of the emission from unlayered solid targets (Au, Pd, CH) have recently been made using an array of moveable filtered diode modules. The data from the angular distribution studies will be presented. A new absolutely calibrated, time-resolving transmission grating spectrometer has been installed at the Nike. The new version has improved spectral resolution, selectable transmission filters, and the potential for simultaneous temporal, spatial, and spectral resolution. Preliminary data from the new spectrometer will be presented and future experiments will be briefly discussed. *Work was supported by DoE

Simulations and measurements of hot-electron generation driven by the multibeam two-plasmon-decay instability

DOE Office of Scientific and Technical Information (OSTI.GOV)

Follett, R. K.; Myatt, J. F.; Shaw, J. G.

We report that multiple-beam experiments relevant to direct-drive inertial confinement fusion show the importance of nonlinear saturation mechanisms in the common-wave two-plasmon-decay (TPD) instability. Planar target experiments on the OMEGA laser used hard-x-ray measurements to study the influence of the linear common-wave growth rate on TPD driven hot-electron production in two drive beam configurations and over a range of overlapped laser intensities from 3.6 to 15.2 x 10 14 W/cm 2. The beam configuration with the larger linear common-wave growth rate had a lower intensity threshold for the onset of hot-electron production, but the linear growth rate did not havemore » a significant impact on hot-electron production at high intensities. The experiments were modeled in 3-D using a hybrid code (LPSE) that combines a wave solver with a particle tracker to self-consistently calculate the electron velocity distribution and evolve electron Landau damping. Finally, good quantitative agreement was obtained between the simulated and measured hotel-electron distributions using a novel technique to account for macroscopic spatial and temporal variations that are present in the experiments.« less

Intensity-enhanced MART for tomographic PIV

NASA Astrophysics Data System (ADS)

Wang, HongPing; Gao, Qi; Wei, RunJie; Wang, JinJun

2016-05-01

A novel technique to shrink the elongated particles and suppress the ghost particles in particle reconstruction of tomographic particle image velocimetry is presented. This method, named as intensity-enhanced multiplicative algebraic reconstruction technique (IntE-MART), utilizes an inverse diffusion function and an intensity suppressing factor to improve the quality of particle reconstruction and consequently the precision of velocimetry. A numerical assessment about vortex ring motion with and without image noise is performed to evaluate the new algorithm in terms of reconstruction, particle elongation and velocimetry. The simulation is performed at seven different seeding densities. The comparison of spatial filter MART and IntE-MART on the probability density function of particle peak intensity suggests that one of the local minima of the distribution can be used to separate the ghosts and actual particles. Thus, ghost removal based on IntE-MART is also introduced. To verify the application of IntE-MART, a real plate turbulent boundary layer experiment is performed. The result indicates that ghost reduction can increase the accuracy of RMS of velocity field.

Changes of the time-varying percentiles of daily extreme temperature in China

NASA Astrophysics Data System (ADS)

Li, Bin; Chen, Fang; Xu, Feng; Wang, Xinrui

2017-11-01

Identifying the air temperature frequency distributions and evaluating the trends in time-varying percentiles are very important for climate change studies. In order to get a better understanding of the recent temporal and spatial pattern of the temperature changes in China, we have calculated the trends in temporal-varying percentiles of the daily extreme air temperature firstly. Then we divide all the stations to get the spatial patterns for the percentile trends using the average linkage cluster analysis method. To make a comparison, the shifts of trends percentile frequency distribution from 1961-1985 to 1986-2010 are also examined. Important results in three aspects have been achieved: (1) In terms of the trends in temporal-varying percentiles of the daily extreme air temperature, the most intense warming for daily maximum air temperature (Tmax) was detected in the upper percentiles with a significant increasing tendency magnitude (>2.5 °C/50year), and the greatest warming for daily minimum air temperature (Tmin) occurred with very strong trends exceeding 4 °C/50year. (2) The relative coherent spatial patterns for the percentile trends were found, and stations for the whole country had been divided into three clusters. The three primary clusters were distributed regularly to some extent from north to south, indicating the possible large influence of the latitude. (3) The most significant shifts of trends percentile frequency distribution from 1961-1985 to 1986-2010 was found in Tmax. More than half part of the frequency distribution show negative trends less than -0.5 °C/50year in 1961-1985, while showing trends less than 2.5 °C/50year in 1986-2010.

Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

DOEpatents

Skupsky, S.; Craxton, R.S.; Soures, J.

1990-10-02

In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temporal oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation. 16 figs.

Systems for controlling the intensity variations in a laser beam and for frequency conversion thereof

DOEpatents

Skupsky, Stanley; Craxton, R. Stephen; Soures, John

1990-01-01

In order to control the intensity of a laser beam so that its intensity varies uniformly and provides uniform illumination of a target, such as a laser fusion target, a broad bandwidth laser pulse is spectrally dispersed spatially so that the frequency components thereof are spread apart. A disperser (grating) provides an output beam which varies spatially in wavelength in at least one direction transverse to the direction of propagation of the beam. Temporal spread (time delay) across the beam is corrected by using a phase delay device (a time delay compensation echelon). The dispersed beam may be amplified with laser amplifiers and frequency converted (doubled, tripled or quadrupled in frequency) with nonlinear optical elements (birefringent crystals). The spectral variation across the beam is compensated by varying the angle of incidence on one of the crystals with respect to the crystal optical axis utilizing a lens which diverges the beam. Another lens after the frequency converter may be used to recollimate the beam. The frequency converted beam is recombined so that portions of different frequency interfere and, unlike interference between waves of the same wavelength, there results an intensity pattern with rapid temoral oscillations which average out rapidly in time thereby producing uniform illumination on target. A distributed phase plate (also known as a random phase mask), through which the spectrally dispersed beam is passed and then focused on a target, is used to provide the interference pattern which becomes nearly modulation free and uniform in intensity in the direction of the spectral variation.

Three-dimensional hydrogeological modelling application to the Alverà mudslide (Cortina d'Ampezzo, Italy)

NASA Astrophysics Data System (ADS)

Bonomi, Tullia; Cavallin, Angelo

1999-10-01

Within the framework of Geographic Information System (GIS), the distributed three-dimensional groundwater model MODFLOW has been applied to evaluate the groundwater processes of the hydrogeological system in the Alverà mudslide (Cortina d'Ampezzo, Italy; test site in the TESLEC Project of the European Union). The application of this model has permitted an analysis of the spatial distribution of the structure (DTM and landslide bottom) and the mass transfer elements of the hydrogeological system. The field survey suggested zoning the area on the basis of the recharge, groundwater fluctuation and drainage system. For each zone, a hydraulic conductivity value to simulate the different recharge and the drainage responses has been assigned. The effect of rainfall infiltration into the ground and its effect on the groundwater table, with different intensity related to different time periods, have been simulated to reproduce the real condition of the area. The applied model can simulate the positive fluctuations of the water table on the whole landslide, with a different response of the hydrogeological system in each zone. The spatial simulated water level distribution is in accordance with the real one, with very small difference between them. The application of distributed three-dimensional models, within the framework of GIS, is an approach which permits data to be continually updated, standardised and integrated.

Spatial distribution of aquatic marine fungi across the western Arctic and sub-arctic.

PubMed

Hassett, Brandon T; Ducluzeau, Anne-Lise L; Collins, Roy E; Gradinger, Rolf

2017-02-01

Fungi are important parasites of primary producers and nutrient cyclers in aquatic ecosystems. In the Pacific-Arctic domain, fungal parasitism is linked to light intensities and algal stress that can elevate disease incidence on algae and reduce diatom concentrations. Fungi are vastly understudied in the marine realm and knowledge of their function is constrained by the current understanding of fungal distribution and drivers on global scales. To investigate the spatial distribution of fungi in the western Arctic and sub-Arctic, we used high throughput methods to sequence 18S rRNA, cloned and sequenced 28S rRNA and microscopically counted chytrid-infected diatoms. We identified a broad distribution of fungal taxa predominated by Chytridiomycota and Dikarya. Phylogenetic analysis of our Chytridiomycota clones placed Arctic marine fungi sister to the order Lobulomycetales. This clade of fungi predominated in fungal communities under ice with low snowpack. Microscopic examination of fixed seawater and sea ice samples revealed chytrids parasitizing diatoms collected across the Arctic that notably infected 25% of a single diatom species in the Bering Sea. The Pezizomycotina comprised > 95% of eukaryotic sequence reads in Greenland, providing preliminary evidence for osmotrophs being a substitute for algae as the base of food webs. © 2016 Society for Applied Microbiology and John Wiley & Sons Ltd.

Monitoring air quality in mountains: Designing an effective network

USGS Publications Warehouse

Peterson, D.L.

2000-01-01

A quantitatively robust yet parsimonious air-quality monitoring network in mountainous regions requires special attention to relevant spatial and temporal scales of measurement and inference. The design of monitoring networks should focus on the objectives required by public agencies, namely: 1) determine if some threshold has been exceeded (e.g., for regulatory purposes), and 2) identify spatial patterns and temporal trends (e.g., to protect natural resources). A short-term, multi-scale assessment to quantify spatial variability in air quality is a valuable asset in designing a network, in conjunction with an evaluation of existing data and simulation-model output. A recent assessment in Washington state (USA) quantified spatial variability in tropospheric ozone distribution ranging from a single watershed to the western third of the state. Spatial and temporal coherence in ozone exposure modified by predictable elevational relationships ( 1.3 ppbv ozone per 100 m elevation gain) extends from urban areas to the crest of the Cascade Range. This suggests that a sparse network of permanent analyzers is sufficient at all spatial scales, with the option of periodic intensive measurements to validate network design. It is imperative that agencies cooperate in the design of monitoring networks in mountainous regions to optimize data collection and financial efficiencies.

High spatial resolution fiber optical sensors for simultaneous temperature and chemical sensing for energy industries

NASA Astrophysics Data System (ADS)

Yan, Aidong; Huang, Sheng; Li, Shuo; Zaghloul, Mohamed; Ohodnicki, Paul; Buric, Michael; Chen, Kevin P.

2017-05-01

This paper demonstrates optical fibers as high-temperature sensor platforms. Through engineering and onfiber integration of functional metal oxide sensory materials, we report the development of an integrated sensor solution to perform temperature and chemical measurements for high-temperature energy applications. Using the Rayleigh optical frequency domain reflectometry (OFDR) distributed sensing scheme, the temperature and hydrogen concentration were measured along the fiber. To overcome the weak Rayleighbackscattering intensity exhibited by conventional optical fibers, an ultrafast laser was used to enhance the Rayleigh scattering by a direct laser writing method. Using the Rayleigh-enhanced fiber as sensor platform, both temperature and hydrogen reaction were monitored at high temperature up to 750°C with 4-mm spatial resolution.

Phase-space analysis of the Schwinger effect in inhomogeneous electromagnetic fields

NASA Astrophysics Data System (ADS)

Kohlfürst, Christian

2018-05-01

Schwinger pair production in spatially and temporally inhomogeneous electric and magnetic fields is studied. The focus is on the particle phase-space distribution within a high-intensity few-cycle pulse. Accurate numerical solutions of a quantum kinetic theory (DHW formalism) are presented in momentum space and, with the aid of coarse-graining techniques, in a mixed spatial-momentum representation. Additionally, signatures of the carrier-envelope phase as well as spin-field interactions are discussed on the basis of a trajectory-based model taking into account instantaneous pair production and relativistic single-particle dynamics. Although our simple semi-classical single-particle model cannot describe every aspect of the particle production process (quantum interferences), essential features such as spin-field interactions are captured.

A statistical evaluation of non-ergodic variogram estimators

USGS Publications Warehouse

Curriero, F.C.; Hohn, M.E.; Liebhold, A.M.; Lele, S.R.

2002-01-01

Geostatistics is a set of statistical techniques that is increasingly used to characterize spatial dependence in spatially referenced ecological data. A common feature of geostatistics is predicting values at unsampled locations from nearby samples using the kriging algorithm. Modeling spatial dependence in sampled data is necessary before kriging and is usually accomplished with the variogram and its traditional estimator. Other types of estimators, known as non-ergodic estimators, have been used in ecological applications. Non-ergodic estimators were originally suggested as a method of choice when sampled data are preferentially located and exhibit a skewed frequency distribution. Preferentially located samples can occur, for example, when areas with high values are sampled more intensely than other areas. In earlier studies the visual appearance of variograms from traditional and non-ergodic estimators were compared. Here we evaluate the estimators' relative performance in prediction. We also show algebraically that a non-ergodic version of the variogram is equivalent to the traditional variogram estimator. Simulations, designed to investigate the effects of data skewness and preferential sampling on variogram estimation and kriging, showed the traditional variogram estimator outperforms the non-ergodic estimators under these conditions. We also analyzed data on carabid beetle abundance, which exhibited large-scale spatial variability (trend) and a skewed frequency distribution. Detrending data followed by robust estimation of the residual variogram is demonstrated to be a successful alternative to the non-ergodic approach.

Multiple coherent light scattering in ultracold rubidium

NASA Astrophysics Data System (ADS)

Kulatunga, P.; Sukenik, C. I.; Havey, M. D.; Kupriyanov, D. V.; Sokolov, I. M.

2001-11-01

We report investigation of multiple coherent light scattering from ^85Rb atoms confined in a magneto-optic trap. In a theoretical study of intensity enhancement of near-resonant backscattered light from cold ^85,87Rb atoms, we consider the dominant mode of double scattering only. Enhancement factors are calculated for all D1 and D2 hyperfine components and for both isotopes. In experimental studies, measurements are made of coherent backscattering of a low-intensity probe beam tuned near the F = 3 - F' = 4 transition in ^85Rb atoms. Polarization of backscattered light is determined by a backscattering polarimeter; the spatial distribution of light intensity is measured by a liquid-nitrogen cooled CCD camera set in the focal plane of the analyzing optics. The instrument has angular resolution of about 100 micro-radians, and a polarization analyzing power of roughly 1000. In this paper we describe the instrument details, including calibration procedures, and progress towards observation of atomic coherent backscattering.

Multiple coherent light scattering in ultracold rubidium

NASA Astrophysics Data System (ADS)

Havey, M. D.; Sukenik, C. I.; Kulatunga, P.; Kupriyanov, D. V.; Sokolov, I. M.

2001-05-01

We report investigation of multiple coherent light scattering from ^85Rb atoms confined in a magneto-optic trap. In a theoretical study of intensity enhancement of near-resonant backscattered light from cold ^85,87Rb atoms, we consider the dominant mode of double scattering only. Enhancement factors are calculated for all D1 and D2 hyperfine components and for both isotopes. In experimental studies, measurements are made of coherent backscattering of a low-intensity probe beam tuned near the F = 3 - F' = 4 transition in ^85Rb atoms. Polarization of backscattered light is determined by a backscattering polarimeter; the spatial distribution of light intensity is measured by a liquid-nitrogen cooled CCD camera set in the focal plane of the analyzing optics. The instrument has angular resolution of about 100 micro-radians, and a polarization analyzing power of roughly 1000. In this paper we describe the instrument details, including calibration procedures, and progress towards observation of atomic coherent backscattering.

Normal incidence X-ray telescope power spectra of X-ray emission from solar active regions. I - Observations. II - Theory

NASA Technical Reports Server (NTRS)

Gomez, Daniel O.; Martens, Petrus C. H.; Golub, Leon

1993-01-01

Fourier analysis is applied to very high resolution image of coronal active regions obtained by the Normal Incidence X-Ray Telescope is used to find a broad isotropic power-law spectrum of the spatial distribution of soft X-ray intensities. Magnetic structures of all sizes are present down to the resolution limit of the instrument. Power spectra for the X-ray intensities of a sample of topologically different active regions are found which fall off with increasing wavenumber as 1/k-cubed. A model is presented that relates the basic features of coronal magnetic fluctuations to the subphotospheric hydrodynamic turbulence that generates them. The model is used to find a theoretical power spectrum for the X-ray intensity which falls off with increasing wavenumber as 1/k-cubed. The implications of a turbulent regime in active regions are discussed.

Recent results of PADReS, the Photon Analysis Delivery and REduction System, from the FERMI FEL commissioning and user operations.

PubMed

Zangrando, Marco; Cocco, Daniele; Fava, Claudio; Gerusina, Simone; Gobessi, Riccardo; Mahne, Nicola; Mazzucco, Eric; Raimondi, Lorenzo; Rumiz, Luca; Svetina, Cristian

2015-05-01

The Photon Analysis Delivery and REduction System of FERMI (PADReS) has been routinely used during the machine commissioning and operations of FERMI since 2011. It has also served the needs of several user runs at the facility from late 2012. The system is endowed with online and shot-to-shot diagnostics giving information about intensity, spatial-angular distribution, spectral content, as well as other diagnostics to determine coherence, pulse length etc. Moreover, PADReS is capable of manipulating the beam in terms of intensity and optical parameters. Regarding the optics, besides a standard refocusing system based on an ellipsoidal mirror, the Kirkpatrick-Baez active optics systems are key elements and have been used intensively to meet users' requirements. A general description of the system is given, together with some selected results from the commissioning/operations/user beam time.

Epidemiology and risk factors analysis of elaphostrongylosis in red deer (Cervus elaphus) from Spain.

PubMed

Vicente, Joaquín; Fernández de Mera, Isabel G; Gortazar, Christian

2006-01-01

We studied the distribution and faecal shedding pattern of the first-stage larvae (L1) of Elaphostrongylus cervi (Nematoda: Protostrongylidae) in the red deer (Cervus elaphus) across Spain, where excretion was widespread. We evaluated the effects of individual, population and environmental factors on E. cervi L1 counts in 18 free-ranging red deer populations in South Central Spain. In this area, prevalence was 71.42+/-2.14% (n = 448) and mean intensity (n = 320) was 74.50+/-10.35. Aggregation of deer at water-holes was positively associated with E. cervi L1 prevalence, possibly due to spatial and temporal odds of infected gastropods, red deer and infective E. cervi L1 larvae being encountered. Prevalence increased with age, and there was also a trend towards males having higher intensities than females. A slightly decreasing age-intensity profile was identified for females, which may suggest a role of acquired immunity.

Geographic Information System and Remote Sensing Approach with Hydrologic Rational Model for Flood Event Analysis in Jakarta

NASA Astrophysics Data System (ADS)

Aditya, M. R.; Hernina, R.; Rokhmatuloh

2017-12-01

Rapid development in Jakarta which generates more impervious surface has reduced the amount of rainfall infiltration into soil layer and increases run-off. In some events, continuous high rainfall intensity could create sudden flood in Jakarta City. This article used rainfall data of Jakarta during 10 February 2015 to compute rainfall intensity and then interpolate it with ordinary kriging technique. Spatial distribution of rainfall intensity then overlaid with run-off coefficient based on certain land use type of the study area. Peak run-off within each cell resulted from hydrologic rational model then summed for the whole study area to generate total peak run-off. For this study area, land use types consisted of 51.9 % industrial, 37.57% parks, and 10.54% residential with estimated total peak run-off 6.04 m3/sec, 0.39 m3/sec, and 0.31 m3/sec, respectively.

Evaluating influence of active tectonics on spatial distribution pattern of floods along eastern Tamil Nadu, India

NASA Astrophysics Data System (ADS)

Selvakumar, R.; Ramasamy, SM.

2014-12-01

Flooding is a naturally recurrent phenomenon that causes severe damage to lives and property. Predictions on flood-prone zones are made based on intensity-duration of rainfall, carrying capacity of drainage, and natural or man-made obstructions. Particularly, the lower part of the drainage system and its adjacent geomorphic landforms like floodplains and deltaic plains are considered for analysis, but stagnation in parts of basins that are far away from major riverine systems is less unveiled. Similarly, uncharacteristic flooding in the upper and middle parts of drainage, especially in zones of an anomalous drainage pattern, is also least understood. Even though topographic differences are attributed for such anomalous spatial occurrence of floods, its genetic cause has to be identified for effective management practice. Added to structural and lithological variations, tectonic movements too impart micro-scale terrain undulations. Because active tectonic movements are slow-occurring, long-term geological processes, its resultant topographical variations and drainage anomalies are least correlated with floods. The recent floods of Tamil Nadu also exhibit a unique distribution pattern emphasizing the role of tectonics over it. Hence a detailed geoinformatics-based analysis was carried out to envisage the relationship between spatial distribution of flood and active tectonic elements such as regional arches and deeps, block faults, and graben and drainage anomalies such as deflected drainage, compressed meander, and eyed drainages. The analysis reveals that micro-scale topographic highs and lows imparted by active tectonic movements and its further induced drainage anomalies have substantially controlled the distribution pattern of flood.

Model-based aberration correction in a closed-loop wavefront-sensor-less adaptive optics system.

PubMed

Song, H; Fraanje, R; Schitter, G; Kroese, H; Vdovin, G; Verhaegen, M

2010-11-08

In many scientific and medical applications, such as laser systems and microscopes, wavefront-sensor-less (WFSless) adaptive optics (AO) systems are used to improve the laser beam quality or the image resolution by correcting the wavefront aberration in the optical path. The lack of direct wavefront measurement in WFSless AO systems imposes a challenge to achieve efficient aberration correction. This paper presents an aberration correction approach for WFSlss AO systems based on the model of the WFSless AO system and a small number of intensity measurements, where the model is identified from the input-output data of the WFSless AO system by black-box identification. This approach is validated in an experimental setup with 20 static aberrations having Kolmogorov spatial distributions. By correcting N=9 Zernike modes (N is the number of aberration modes), an intensity improvement from 49% of the maximum value to 89% has been achieved in average based on N+5=14 intensity measurements. With the worst initial intensity, an improvement from 17% of the maximum value to 86% has been achieved based on N+4=13 intensity measurements.

Focused ultrasound transducer spatial peak intensity estimation: a comparison of methods

NASA Astrophysics Data System (ADS)

Civale, John; Rivens, Ian; Shaw, Adam; ter Haar, Gail

2018-03-01

Characterisation of the spatial peak intensity at the focus of high intensity focused ultrasound transducers is difficult because of the risk of damage to hydrophone sensors at the high focal pressures generated. Hill et al (1994 Ultrasound Med. Biol. 20 259-69) provided a simple equation for estimating spatial-peak intensity for solid spherical bowl transducers using measured acoustic power and focal beamwidth. This paper demonstrates theoretically and experimentally that this expression is only strictly valid for spherical bowl transducers without a central (imaging) aperture. A hole in the centre of the transducer results in over-estimation of the peak intensity. Improved strategies for determining focal peak intensity from a measurement of total acoustic power are proposed. Four methods are compared: (i) a solid spherical bowl approximation (after Hill et al 1994 Ultrasound Med. Biol. 20 259-69), (ii) a numerical method derived from theory, (iii) a method using measured sidelobe to focal peak pressure ratio, and (iv) a method for measuring the focal power fraction (FPF) experimentally. Spatial-peak intensities were estimated for 8 transducers at three drive powers levels: low (approximately 1 W), moderate (~10 W) and high (20-70 W). The calculated intensities were compared with those derived from focal peak pressure measurements made using a calibrated hydrophone. The FPF measurement method was found to provide focal peak intensity estimates that agreed most closely (within 15%) with the hydrophone measurements, followed by the pressure ratio method (within 20%). The numerical method was found to consistently over-estimate focal peak intensity (+40% on average), however, for transducers with a central hole it was more accurate than using the solid bowl assumption (+70% over-estimation). In conclusion, the ability to make use of an automated beam plotting system, and a hydrophone with good spatial resolution, greatly facilitates characterisation of the FPF, and consequently gives improved confidence in estimating spatial peak intensity from measurement of acoustic power.

Decision algorithm for data center vortex beam receiver

NASA Astrophysics Data System (ADS)

Kupferman, Judy; Arnon, Shlomi

2017-12-01

We present a new scheme for a vortex beam communications system which exploits the radial component p of Laguerre-Gauss modes in addition to the azimuthal component l generally used. We derive a new encoding algorithm which makes use of the spatial distribution of intensity to create an alphabet dictionary for communication. We suggest an application of the scheme as part of an optical wireless link for intra data center communication. We investigate the probability of error in decoding, for several detector options.

Spatial Distribution of Amorphization Intensity in B4C during Rate-Dependent Indentation and Ballistic Impact Processes [1.2 Solid Mechanics

DTIC Science & Technology

2017-11-17

SECURITY CLASSIFICATION OF: At high pressures, such as those encountered in ballistic impact, boron carbide (B4C) suffers from loss of crystallinity...ELEMENT NUMBER 5b. GRANT NUMBER 5a. CONTRACT NUMBER Form Approved OMB NO . 0704-0188 3. DATES COVERED (From - To) - Approved for public release...Highway, Suite 1204, Arlington VA, 22202-4302. Respondents should be aware that notwithstanding any other provision of law, no person shall be subject

Absolute Bunch Length Measurements at the ALS by Incoherent Synchrotron Radiation Fluctuation Analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Filippetto, D.; /Frascati; Sannibale, F.

2008-01-24

By analyzing the pulse to pulse intensity fluctuations of the radiation emitted by a charge particle in the incoherent part of the spectrum, it is possible to extract information about the spatial distribution of the beam. At the Advanced Light Source (ALS) of the Lawrence Berkeley National Laboratory, we have developed and tested a simple scheme based on this principle that allows for the absolute measurement of the bunch length. A description of the method and the experimental results are presented.

Spatial and Temporal Variations of Infrared Emissions in the Upper Atmosphere. 3. 5.3-μm Nitric Oxide Emission

NASA Astrophysics Data System (ADS)

Semenov, A. I.; Medvedeva, I. V.; Perminov, V. I.

2018-03-01

The results of rocket and satellite measurements available in the literature of 5.3-μm nitric oxide emission in the upper atmosphere have been systematized and analyzed. Analytical dependences describing the height distribution of volumetric intensity of 5.3-μm emission of the NO molecule and its variations in a range of heights from 100 to 130 km as a function of the time of year, day, latitude, and solar activity have been obtained.

Evaluation of True Power Luminous Efficiency from Experimental Luminance Values

NASA Astrophysics Data System (ADS)

Tsutsui, Tetsuo; Yamamato, Kounosuke

1999-05-01

A method for obtaining true external power luminous efficiencyfrom experimentally obtained luminance in organic light-emittingdiodes (LEDs) wasdemonstrated. Conventional two-layer organic LEDs with different electron-transport layer thicknesses wereprepared. Spatial distributions of emission intensities wereobserved. The large deviation in both emission spectra and spatialemission patterns were observed when the electron-transport layerthickness was varied. The deviation of emission patterns from thestandard Lambertian pattern was found to cause overestimations ofpower luminous efficiencies as large as 30%. A method for evaluatingcorrection factors was proposed.

Relief diffracted elements recorded on absorbent photopolymers.

PubMed

Gallego, S; Márquez, A; Ortuño, M; Francés, J; Pascual, I; Beléndez, A

2012-05-07

Relief surface changes provide interesting possibilities for storing diffractive optical elements on photopolymers and are an important source of information for characterizing and understanding the material behavior. In this paper we use a 3-dimensional model, based on direct parameter measurements, for predicting the relief structures generated on without-coverplate photopolymers. We have analyzed different spatial frequency and recording intensity distributions such as binary and blazed periodic patterns. This model was successfully applied to different photopolymers with different values of monomer diffusion.

Extracting conformational structure information of benzene molecules via laser-induced electron diffraction

DOE PAGES

Ito, Yuta; Wang, Chuncheng; Le, Anh-Thu; ...

2016-05-01

Here, we have measured the angular distributions of high energy photoelectrons of benzene molecules generated by intense infrared femtosecond laser pulses. These electrons arise from the elastic collisions between the benzene ions with the previously tunnel-ionized electrons that have been driven back by the laser field. Theory shows that laser-free elastic differential cross sections (DCSs) can be extracted from these photoelectrons, and the DCS can be used to retrieve the bond lengths of gas-phase molecules similar to the conventional electron diffraction method. From our experimental results, we have obtained the C-C and C-H bond lengths of benzene with a spatialmore » resolution of about 10 pm. Our results demonstrate that laser induced electron diffraction (LIED) experiments can be carried out with the present-day ultrafast intense lasers already. Looking ahead, with aligned or oriented molecules, more complete spatial information of the molecule can be obtained from LIED, and applying LIED to probe photo-excited molecules, a “molecular movie” of the dynamic system may be created with sub-A°ngstrom spatial and few-ten femtosecond temporal resolutions.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ito, Yuta; Wang, Chuncheng; Le, Anh-Thu

Here, we have measured the angular distributions of high energy photoelectrons of benzene molecules generated by intense infrared femtosecond laser pulses. These electrons arise from the elastic collisions between the benzene ions with the previously tunnel-ionized electrons that have been driven back by the laser field. Theory shows that laser-free elastic differential cross sections (DCSs) can be extracted from these photoelectrons, and the DCS can be used to retrieve the bond lengths of gas-phase molecules similar to the conventional electron diffraction method. From our experimental results, we have obtained the C-C and C-H bond lengths of benzene with a spatialmore » resolution of about 10 pm. Our results demonstrate that laser induced electron diffraction (LIED) experiments can be carried out with the present-day ultrafast intense lasers already. Looking ahead, with aligned or oriented molecules, more complete spatial information of the molecule can be obtained from LIED, and applying LIED to probe photo-excited molecules, a “molecular movie” of the dynamic system may be created with sub-A°ngstrom spatial and few-ten femtosecond temporal resolutions.« less

Modeling of a historical earthquake in Erzincan, Turkey (Ms 7.8, in 1939) using regional seismological information obtained from a recent event

NASA Astrophysics Data System (ADS)

Karimzadeh, Shaghayegh; Askan, Aysegul

2018-04-01

Located within a basin structure, at the conjunction of North East Anatolian, North Anatolian and Ovacik Faults, Erzincan city center (Turkey) is one of the most hazardous regions in the world. Combination of the seismotectonic and geological settings of the region has resulted in series of significant seismic activities including the 1939 (Ms 7.8) as well as the 1992 (Mw = 6.6) earthquakes. The devastative 1939 earthquake occurred in the pre-instrumental era in the region with no available local seismograms. Thus, a limited number of studies exist on that earthquake. However, the 1992 event, despite the sparse local network at that time, has been studied extensively. This study aims to simulate the 1939 Erzincan earthquake using available regional seismic and geological parameters. Despite several uncertainties involved, such an effort to quantitatively model the 1939 earthquake is promising, given the historical reports of extensive damage and fatalities in the area. The results of this study are expressed in terms of anticipated acceleration time histories at certain locations, spatial distribution of selected ground motion parameters and felt intensity maps in the region. Simulated motions are first compared against empirical ground motion prediction equations derived with both local and global datasets. Next, anticipated intensity maps of the 1939 earthquake are obtained using local correlations between peak ground motion parameters and felt intensity values. Comparisons of the estimated intensity distributions with the corresponding observed intensities indicate a reasonable modeling of the 1939 earthquake.

Latitudinal variability of large-scale coronal temperature and its association with the density and the global magnetic field

NASA Technical Reports Server (NTRS)

Guhathakurta, M.; Fisher, R. R.

1994-01-01

In this paper we utilize the latitiude distribution of the coronal temperature during the period 1984-1992 that was derived in a paper by Guhathakurta et al, 1993, utilizing ground-based intensity observations of the green (5303 A Fe XIV) and red (6374 A Fe X) coronal forbidden lines from the National Solar Observatory at Sacramento Peak, and establish it association with the global magnetic field and the density distributions in the corona. A determination of plasma temperature, T, was estimated from the intensity ratio Fe X/Fe XIV (where T is inversely proportional to the ratio), since both emission lines come from ionized states of Fe, and the ratio is only weakly dependent on density. We observe that there is a large-scale organization of the inferred coronal temperature distribution that is associated with the large-scale, weak magnetic field structures and bright coronal features; this organization tends to persist through most of the magnetic activity cycle. These high-temperature structures exhibit time-space characteristics which are similar to those of the polar crown filaments. This distribution differs in spatial and temporal characterization from the traditional picture of sunspot and active region evolution over the range of the sunspot cycle, which are manifestations of the small-scale, strong magnetic field regions.

Femtosecond noncollinear SFG dynamics in autocorrelator setup at low level of photons

NASA Astrophysics Data System (ADS)

Tenishev, Vladimir P.; Persson, A.; Larsson, J.

2004-06-01

We report here the characteristics of noncollinear sum frequency generation in nonlinear KDP crystals by ultrashort (80 fsec) IR pulses irradiated by the intense Ti:Sapphire laser and their behavior in single shot auto-crosscorrelator (ACC) configuration. In particular we study the case where one of the beams is very weak. Our aim is to develop a procedure to provide delay time signal between light pulses for time resolved pump probe experiments based on the extraction of the phase-matched SHG spatial distribution by means of pulse shape analysis technique. We intend to apply these results to synchronize a weak short-pulse source and an intense Ti:Sapphire laser and to measure the pulse time jitter between them.

Numerical simulation of laser ion acceleration at ultra high intensity

NASA Astrophysics Data System (ADS)

Tatomirescu, Dragos; Popescu, Alexandra; d'Humières, Emmanuel; Vizman, Daniel

2017-01-01

With the latest advances in attainable laser intensity, the need to obtain better quality ion and electron beams has been a major field of research. This paper studies the effects of different target density profiles on the spatial distribution of the accelerated particles, the maximum energies achieved, and the characteristics of the electromagnetic fields using the same laser pulse parameters. The study starts by describing a baseline for a flat target which presents a proton-rich microdot on its backside. The effects of introducing a target curvature and, further on, a cone laser focusing structure are compared with the flat target baseline results. The maximum energy obtained increases when using complex structures, and also a smaller divergence of the ion beam is observed.

Multiple ionization of neon by soft x-rays at ultrahigh intensity

NASA Astrophysics Data System (ADS)

Guichard, R.; Richter, M.; Rost, J.-M.; Saalmann, U.; Sorokin, A. A.; Tiedtke, K.

2013-08-01

At the free-electron laser FLASH, multiple ionization of neon atoms was quantitatively investigated at photon energies of 93.0 and 90.5 eV. For ion charge states up to 6+, we compare the respective absolute photoionization yields with results from a minimal model and an elaborate description including standard sequential and direct photoionization channels. Both approaches are based on rate equations and take into account a Gaussian spatial intensity distribution of the laser beam. From the comparison we conclude that photoionization up to a charge of 5+ can be described by the minimal model which we interpret as sequential photoionization assisted by electron shake-up processes. For higher charges, the experimental ionization yields systematically exceed the elaborate rate-based prediction.

Neural Correlates of Temporal-Order Judgments versus Those of Spatial-Location: Deactivation of Hippocampus May Facilitate Spatial Performance

ERIC Educational Resources Information Center

Rekkas, P. V.; Westerveld, M.; Skudlarski, P.; Zumer, J.; Pugh, K.; Spencer, D. D.; Constable, R. T.

2005-01-01

The retrieval of temporal-order versus spatial-location information was investigated using fMRI. The primary finding in the hippocampus proper, seen in region of interest analyses, was an increase in BOLD signal intensity for temporal retrieval, and a decrease in signal intensity for spatial retrieval, relative to baseline. The negative BOLD…

Fluorescence labeling of carbonylated lipids and proteins in cells using coumarin-hydrazide

PubMed Central

Vemula, Venukumar; Ni, Zhixu; Fedorova, Maria

2015-01-01

Carbonylation is a generic term which refers to reactive carbonyl groups present in biomolecules due to oxidative reactions induced by reactive oxygen species. Carbonylated proteins, lipids and nucleic acids have been intensively studied and often associated with onset or progression of oxidative stress related disorders. In order to reveal underlying carbonylation pathways and biological relevance, it is crucial to study their intracellular formation and spatial distribution. Carbonylated species are usually identified and quantified in cell lysates and body fluids after derivatization using specific chemical probes. However, spatial cellular and tissue distribution have been less often investigated. Here, we report coumarin-hydrazide, a fluorescent chemical probe for time- and cost-efficient labeling of cellular carbonyls followed by fluorescence microscopy to evaluate their intracellular formation both in time and space. The specificity of coumarin-hydrazide was confirmed in time- and dose-dependent experiments using human primary fibroblasts stressed with paraquat and compared with conventional DNPH-based immunocytochemistry. Both techniques stained carbonylated species accumulated in cytoplasm with strong perinuclear clustering. Using a complimentary array of analytical methods specificity of coumarin-hydrazide probe towards both protein- and lipid-bound carbonyls has been shown. Additionally, co-distribution of carbonylated species and oxidized phospholipids was demonstrated. PMID:25974625

Spatial distribution of soil radon as a tool to recognize active faulting on an active volcano: the example of Mt. Etna (Italy).

PubMed

Neri, Marco; Giammanco, Salvatore; Ferrera, Elisabetta; Patanè, Giuseppe; Zanon, Vittorio

2011-09-01

This study concerns measurements of radon and thoron emissions from soil carried out in 2004 on the eastern flank of Mt. Etna, in a zone characterized by the presence of numerous seismogenic and aseismic faults. The statistical treatment of the geochemical data allowed recognizing anomaly thresholds for both parameters and producing distribution maps that highlighted a significant spatial correlation between soil gas anomalies and tectonic lineaments. The seismic activity occurring in and around the study area during 2004 was analyzed, producing maps of hypocentral depth and released seismic energy. Both radon and thoron anomalies were located in areas affected by relatively deep (5-10 km depth) seismic activity, while less evident correlation was found between soil gas anomalies and the released seismic energy. This study confirms that mapping the distribution of radon and thoron in soil gas can reveal hidden faults buried by recent soil cover or faults that are not clearly visible at the surface. The correlation between soil gas data and earthquakes depth and intensity can give some hints on the source of gas and/or on fault dynamics. Copyright © 2011 Elsevier Ltd. All rights reserved.

Accuracy improvement in laser stripe extraction for large-scale triangulation scanning measurement system

NASA Astrophysics Data System (ADS)

Zhang, Yang; Liu, Wei; Li, Xiaodong; Yang, Fan; Gao, Peng; Jia, Zhenyuan

2015-10-01

Large-scale triangulation scanning measurement systems are widely used to measure the three-dimensional profile of large-scale components and parts. The accuracy and speed of the laser stripe center extraction are essential for guaranteeing the accuracy and efficiency of the measuring system. However, in the process of large-scale measurement, multiple factors can cause deviation of the laser stripe center, including the spatial light intensity distribution, material reflectivity characteristics, and spatial transmission characteristics. A center extraction method is proposed for improving the accuracy of the laser stripe center extraction based on image evaluation of Gaussian fitting structural similarity and analysis of the multiple source factors. First, according to the features of the gray distribution of the laser stripe, evaluation of the Gaussian fitting structural similarity is estimated to provide a threshold value for center compensation. Then using the relationships between the gray distribution of the laser stripe and the multiple source factors, a compensation method of center extraction is presented. Finally, measurement experiments for a large-scale aviation composite component are carried out. The experimental results for this specific implementation verify the feasibility of the proposed center extraction method and the improved accuracy for large-scale triangulation scanning measurements.

Assessing the spatial distribution of glyphosate-AMPA in an Argentinian farm field using a pedometric technique

NASA Astrophysics Data System (ADS)

Barbera, Agustin; Zamora, Martin; Domenech, Marisa; Vega-Becerra, Andres; Castro-Franco, Mauricio

2017-04-01

The cultivation of transgenic glyphosate-resistant crops has been the most rapidly adopted crop technology in Argentina since 1997. Thus, more than 180 million liters of the broad-spectrum herbicide glyphosate (N - phosphonomethylglicine) are applied every year. The intensive use of glyphosate combined with geomorphometrical characteristics of the Pampa region is a matter of environmental concern. An integral component of assessing the risk of soil contamination in farm fields is to describe the spatial distribution of the levels of contaminant agent. Application of pedometric techniques for this purpose has been scarcely demonstrated. These techniques could provide an estimate of the concentration at a given unsampled location, as well as the probability that concentration will exceed the critical threshold concentration. In this work, a pedometric technique for assessing the spatial distribution of glyphosate in farm fields was developed. A field located at INTA Barrow, Argentina (Lat: -38.322844, Lon: -60.25572) which has a great soil spatial variability, was divided by soil-specific zones using a pedometric technique. This was developed integrating INTA Soil Survey information and a digital elevation model (DEM) obtained from a DGPS. Firstly, 10 topographic indices derived from a DEM were computed in a Random Forest algorithm to obtain a classification model for soil map units (SMU). Secondly, a classification model was applied to those topographic indices but at a scale higher than 1:1000. Finally, a spatial principal component analysis and a clustering using Fuzzy K-means were used into each SMU. From this clustering, three soil-specific zones were determined which were also validated through apparent electrical conductivity (CEa) measurements. Three soil sample points were determined by zone. In each one, samples from 0-10, 10-20 and 20-40cm depth were taken. Glyphosate content and AMPA in each soil sample were analyzed using de UPLC-MS/MS ESI (+/-). Only AMPA at 10-20 cm depth had significant difference among soil-specific zones. However, marked trends for glyphosate content and AMPA were clearly shown among zones. These results suggest that (i) the presence of glyphosate and AMPA has spatial patterns distribution related to soil properties at field scale; and (ii) the proposed technique allowed to determine soil-specific zones related to the spatial distribution of glyphosate and AMPA fast, cost-effective and accurately. In further works, we would suggest adding new soil information sources to improve soil-specific zone delimitation.

Techniques for detecting the Cherenkov light from cascade showers in water

NASA Astrophysics Data System (ADS)

Khomyakov, V. A.; Bogdanov, A. G.; Kindin, V. V.; Kokoulin, R. P.; Petrukhin, A. A.; Khokhlov, S. S.; Shutenko, V. V.; Yashin, I. I.

2018-01-01

The NEVOD Cherenkov water detector (CWD) features a denser lattice of sensitive elements than the existing large-scale CWDs, whereby the spatial distribution of Cherenkov light from cascade showers is sampled with a superior resolution of 0.5 m, which is close to one radiation length for water (36 cm). The experimental techniques for investigating the Cherenkov light generated by particle cascades in water is proposed. The dependence of light intensity on the depth of shower development is for the first time measured at different distances from the shower axis. The results are compared with the Cherenkov light distributions predicted by various model descriptions for the scattering of cascade particles.

Factors Impacting Spatial Patterns of Snow Distribution in a Small Catchment near Nome, AK

NASA Astrophysics Data System (ADS)

Chen, M.; Wilson, C. J.; Charsley-Groffman, L.; Busey, R.; Bolton, W. R.

2017-12-01

Snow cover plays an important role in the climate, hydrology and ecological systems of the Arctic due to its influence on the water balance, thermal regimes, vegetation and carbon flux. Thus, snow depth and coverage have been key components in all the earth system models but are often poorly represented for arctic regions, where fine scale snow distribution data is sparse. The snow data currently used in the models is at coarse resolution, which in turn leads to high uncertainty in model predictions. Through the DOE Office of Science Next Generation Ecosystem Experiment, NGEE-Arctic, high resolution snow distribution data is being developed and applied in catchment scale models to ultimately improve representation of snow and its interactions with other model components in the earth system models . To improve these models, it is important to identify key factors that control snow distribution and quantify the impacts of those factors on snow distribution. In this study, two intensive snow depth surveys (1 to 10 meters scale) were conducted for a 2.3 km2 catchment on the Teller road, near Nome, AK in the winter of 2016 and 2017. We used a statistical model to quantify the impacts of vegetation types, macro-topography, micro-topography, and meteorological parameters on measured snow depth. The results show that snow spatial distribution was similar between 2016 and 2017, snow depth was spatially auto correlated over small distance (2-5 meters), but not spatially auto correlated over larger distance (more than 2-5 meters). The coefficients of variation of snow depth was above 0.3 for all the snow survey transects (500-800 meters long). Variation of snow depth is governed by vegetation height, aspect, slope, surface curvature, elevation and wind speed and direction. We expect that this empirical statistical model can be used to estimate end of winter snow depth for the whole watershed and will further develop the model using data from other arctic regions to estimate seasonally dynamic snow coverage and properties for use in catchment scale to pan-Arctic models.

Coastal zone color scanner pigment concentrations in the southern ocean and relationships to geophysical surface features

NASA Technical Reports Server (NTRS)

Comiso, J. C.; Mcclain, C. R.; Sullivan, C. W.; Ryan, J. P.; Leonard, C. L.

1993-01-01

Climatological data on the distribution of surface pigment fields in the entire southern ocean over a seasonal cycle are examined. The occurrence of intense phytoplankton blooms during austral summer months and during other seasons in different regions is identified and analyzed. The highest pigment concentrations are observed at high latitudes and over regions with water depths usually less than 600 m. Basin-scale pigment distribution shows a slightly asymmetric pattern of enhanced pigment concentrations about Antarctica, with enhanced concentrations extending to lower latitudes in the Atlantic and Indian sectors than in the Pacific sector. A general increase in pigment concentrations is evident from the low latitudes toward the Antarctic circumpolar region. Spatial relationships between pigment and archived geophysical data reveal significant correlation between pigment distributions and both bathymetry and wind stress, while general hemispheric scale patterns of pigment distributions are most coherent with the geostrophic flow of the Antarctic Circumpolar Current.

Beam shaping in high-power laser systems with using refractive beam shapers

NASA Astrophysics Data System (ADS)

Laskin, Alexander; Laskin, Vadim

2012-06-01

Beam Shaping of the spatial (transverse) profile of laser beams is highly desirable by building optical systems of high-power lasers as well in various applications with these lasers. Pumping of the crystals of Ti:Sapphire lasers by the laser radiation with uniform (flattop) intensity profile improves performance of these ultrashort pulse high-power lasers in terms of achievable efficiency, peak-power and stability, output beam profile. Specifications of the solid-state lasers built according to MOPA configuration can be also improved when radiation of the master oscillator is homogenized and then is amplified by the power amplifier. Features of building these high power lasers require that a beam shaping solution should be capable to work with single mode and multimode beams, provide flattop and super-Gauss intensity distributions, the consistency and divergence of a beam after the intensity re-distribution should be conserved and low absorption provided. These specific conditions are perfectly fulfilled by the refractive field mapping beam shapers due to their unique features: almost lossless intensity profile transformation, low output divergence, high transmittance and flatness of output beam profile, extended depth of field, adaptability to real intensity profiles of TEM00 and multimode laser sources. Combining of the refractive field mapping beam shapers with other optical components, like beam-expanders, relay imaging lenses, anamorphic optics makes it possible to generate the laser spots of necessary shape, size and intensity distribution. There are plenty of applications of high-power lasers where beam shaping bring benefits: irradiating photocathode of Free Electron Lasers (FEL), material ablation, micromachining, annealing in display making techniques, cladding, heat treating and others. This paper will describe some design basics of refractive beam shapers of the field mapping type, with emphasis on the features important for building and applications of high-power laser sources. There will be presented results of applying the refractive beam shapers in real installations.

What Do They Have in Common? Drivers of Streamflow Spatial Correlation and Prediction of Flow Regimes in Ungauged Locations

NASA Astrophysics Data System (ADS)

Betterle, A.; Radny, D.; Schirmer, M.; Botter, G.

2017-12-01

The spatial correlation of daily streamflows represents a statistical index encapsulating the similarity between hydrographs at two arbitrary catchment outlets. In this work, a process-based analytical framework is utilized to investigate the hydrological drivers of streamflow spatial correlation through an extensive application to 78 pairs of stream gauges belonging to 13 unregulated catchments in the eastern United States. The analysis provides insight on how the observed heterogeneity of the physical processes that control flow dynamics ultimately affect streamflow correlation and spatial patterns of flow regimes. Despite the variability of recession properties across the study catchments, the impact of heterogeneous drainage rates on the streamflow spatial correlation is overwhelmed by the spatial variability of frequency and intensity of effective rainfall events. Overall, model performances are satisfactory, with root mean square errors between modeled and observed streamflow spatial correlation below 10% in most cases. We also propose a method for estimating streamflow correlation in the absence of discharge data, which proves useful to predict streamflow regimes in ungauged areas. The method consists in setting a minimum threshold on the modeled flow correlation to individuate hydrologically similar sites. Catchment outlets that are most correlated (ρ>0.9) are found to be characterized by analogous streamflow distributions across a broad range of flow regimes.

Microscale soil structure development after glacial retreat - using machine-learning based segmentation of elemental distributions obtained by NanoSIMS

NASA Astrophysics Data System (ADS)

Schweizer, Steffen; Schlueter, Steffen; Hoeschen, Carmen; Koegel-Knabner, Ingrid; Mueller, Carsten W.

2017-04-01

Soil organic matter (SOM) is distributed on mineral surfaces depending on physicochemical soil properties that vary at the submicron scale. Nanoscale secondary ion mass spectrometry (NanoSIMS) can be used to visualize the spatial distribution of up to seven elements simultaneously at a lateral resolution of approximately 100 nm from which patterns of SOM coatings can be derived. Existing computational methods are mostly confined to visualization and lack spatial quantification measures of coverage and connectivity of organic matter coatings. This study proposes a methodology for the spatial analysis of SOM coatings based on supervised pixel classification and automatic image analysis of the 12C, 12C14N (indicative for SOM) and 16O (indicative for mineral surfaces) secondary ion distributions. The image segmentation of the secondary ion distributions into mineral particle surface and organic coating was done with a machine learning algorithm, which accounts for multiple features like size, color, intensity, edge and texture in all three ion distributions simultaneously. Our workflow allowed the spatial analysis of differences in the SOM coverage during soil development in the Damma glacier forefield (Switzerland) based on NanoSIMS measurements (n=121; containing ca. 4000 particles). The Damma chronosequence comprises several stages of soil development with increasing ice-free period (from ca. 15 to >700 years). To investigate mineral-associated SOM in the developing soil we obtained clay fractions (<2 μm) from two density fractions: light mineral (1.6 to 2.2 g cm3) and heavy mineral (>2.2 g cm3). We found increased coverage and a simultaneous development from patchy-distributed organic coatings to more connected coatings with increasing time after glacial retreat. The normalized N:C ratio (12C14N: (12C14N + 12C)) on the organic matter coatings was higher in the medium-aged soils than in the young and mature ones in both heavy and light mineral fraction. This reflects the sequential accumulation of proteinaceous SOM in the medium-aged soils and C-rich compounds in the mature soils. The results of our microscale image analysis correlated well with the SOM concentration of the fractions measured by elemental analyzer. Image analysis in combination with secondary ion distributions provides a powerful tool at the required microscale and enhances our mechanistic understanding of SOM stabilization in soil.

Beam shaping with vectorial vortex beams under low numerical aperture illumination condition

NASA Astrophysics Data System (ADS)

Dai, Jianning; Zhan, Qiwen

2008-08-01

In this paper we propose and demonstrate a novel beam shaping method using vectorial vortex beam. A vectorial vortex beam is laser beam with polarization singularity in the beam cross section. This type of beams can be decomposed into two orthogonally polarized components. Each of the polarized components could have different vortex characteristics, and consequently, different intensity distribution when focused by lens. Beam shaping in the far field can be achieved by adjusting the relative weighing of these two components. As one example, we study the vectorial vortex that consists of a linearly polarized Gaussian component and a vortex component polarized orthogonally. When such a vectorial vortex beam is focus by low NA lens, the Gaussian component gives rise to a focal intensity distribution with a solid centre while the vortex component gives rise to a donut distribution with hollow dark center. The shape of the focus can be continuously varied by continuously adjusting the relative weight of the two components. Under appropriate conditions, flat top focusing can be obtained. We experimentally demonstrate the creation of such beams with a liquid crystal spatial light modulator. Flattop focus obtained by vectorial vortex beams with topological charge of +1 has been obtained.

Three Radial Gaps in the Disk of TW Hydrae Imaged with SPHERE

NASA Astrophysics Data System (ADS)

van Boekel, R.; Henning, Th.; Menu, J.; de Boer, J.; Langlois, M.; Müller, A.; Avenhaus, H.; Boccaletti, A.; Schmid, H. M.; Thalmann, Ch.; Benisty, M.; Dominik, C.; Ginski, Ch.; Girard, J. H.; Gisler, D.; Lobo Gomes, A.; Menard, F.; Min, M.; Pavlov, A.; Pohl, A.; Quanz, S. P.; Rabou, P.; Roelfsema, R.; Sauvage, J.-F.; Teague, R.; Wildi, F.; Zurlo, A.

2017-03-01

We present scattered light images of the TW Hya disk performed with the Spectro-Polarimetric High-contrast Exoplanet REsearch instrument in Polarimetric Differential Imaging mode at 0.63, 0.79, 1.24, and 1.62 μm. We also present H2/H3-band angular differential imaging (ADI) observations. Three distinct radial depressions in the polarized intensity distribution are seen, around ≈85, ≈21, and ≲6 au.21 The overall intensity distribution has a high degree of azimuthal symmetry; the disk is somewhat brighter than average toward the south and darker toward the north-west. The ADI observations yielded no signifiant detection of point sources in the disk. Our observations have a linear spatial resolution of 1-2 au, similar to that of recent ALMA dust continuum observations. The sub-micron-sized dust grains that dominate the light scattering in the disk surface are strongly coupled to the gas. We created a radiative transfer disk model with self-consistent temperature and vertical structure iteration and including grain size-dependent dust settling. This method may provide independent constraints on the gas distribution at higher spatial resolution than is feasible with ALMA gas line observations. We find that the gas surface density in the “gaps” is reduced by ≈50% to ≈80% relative to an unperturbed model. Should embedded planets be responsible for carving the gaps then their masses are at most a few 10 {{{M}}}\\oplus . The observed gaps are wider, with shallower flanks, than expected for planet-disk interaction with such low-mass planets. If forming planetary bodies have undergone collapse and are in the “detached phase,” then they may be directly observable with future facilities such as the Mid-Infrared E-ELT Imager and Spectrograph at the E-ELT.

Direct optical measurement of the on-shot incoherent focal spot and intensity contrast on the OMEGA EP laser

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorrer, C.; Consentino, A.; Irwin, D.

Characterizing the prepulse temporal contrast of optical pulses is required to understand their interaction with matter. Light with relatively low intensity can interact with the target before the main high-intensity pulse. Estimating the intensity contrast, instead of the spatially averaged power contrast, is important to understand intensity-dependent laser–matter interactions. A direct optical approach to determining the on-shot intensity of the incoherent pedestal on an aberrated high-intensity laser system is presented. The spatially resolved focal spot of the incoherent pedestal preceding the main coherent pulse and the intensity contrast are calculated using experimental data. Furthermore, this technique is experimentally validated onmore » one of the chirped pulse amplification beamlines of the OMEGA EP Laser System. The intensity contrast of a 1-kJ, 10-ps laser pulse is shown to be ~10× higher than the power contrast because of the larger spatial extent of the incoherent focal spot relative to the coherent focal spot.« less

Direct optical measurement of the on-shot incoherent focal spot and intensity contrast on the OMEGA EP laser

DOE PAGES

Dorrer, C.; Consentino, A.; Irwin, D.

2016-05-18

Characterizing the prepulse temporal contrast of optical pulses is required to understand their interaction with matter. Light with relatively low intensity can interact with the target before the main high-intensity pulse. Estimating the intensity contrast, instead of the spatially averaged power contrast, is important to understand intensity-dependent laser–matter interactions. A direct optical approach to determining the on-shot intensity of the incoherent pedestal on an aberrated high-intensity laser system is presented. The spatially resolved focal spot of the incoherent pedestal preceding the main coherent pulse and the intensity contrast are calculated using experimental data. Furthermore, this technique is experimentally validated onmore » one of the chirped pulse amplification beamlines of the OMEGA EP Laser System. The intensity contrast of a 1-kJ, 10-ps laser pulse is shown to be ~10× higher than the power contrast because of the larger spatial extent of the incoherent focal spot relative to the coherent focal spot.« less

The distribution of atomic hydrogen and oxygen in the magnetosphere of Saturn

NASA Astrophysics Data System (ADS)

Melin, Henrik; Shemansky, Don E.; Liu, Xianming

2009-12-01

The intensity of H Ly α1216A˚ ( 2P- 1S) and OI 1304A˚ ( 2p33s3S-2p4P) is mapped in the magnetosphere of Saturn using the ultraviolet imaging spectrograph (UVIS) [Esposito, L.W., Barth, C.A., Colwell, J.E., Lawrence, G.M., McClintock, W.E., Stewart, A.I.F., Keller, H.U., Korth, A., Lauche, H., Festou, M.C., Lane, A.L., Hansen, C.J., Maki, J.N., West, R.A., Jahn, H., Reulke, R., Warlich, K., Shemansky, D.E., Yung, Y.L., 2004. The Cassini ultraviolet imaging spectrograph investigation. Space Science Reviews 115, 299-361] onboard Cassini. Spatial coverage is built up by stepping the slit sequentially across the system (system scan). Data are obtained at a large range of space-craft-Saturn distances. The observed atomic hydrogen distribution is very broad, extending beyond 40RS in the equatorial plane, with the intensity increasing with decreasing distances to Saturn. The distribution displays persistent local-time asymmetries, and is seen connecting continuously to the upper atmosphere of the planet at sub-solar latitudes located well outside of the equatorial (ring) plane. This is consistent with the source of the atomic hydrogen being located at the top of the atmosphere on the sun-lit side of the planet on the southern hemisphere. In addition there are a number of temporally persistent features in the intensity distribution, indicating a complex hydrogen energy distribution. The emission from OI 1304A˚ is generally distributed as a broad torus centered around ˜4RS although the position of the peak intensity can vary by as much as ±1RS. There is significant intensity present out to ±10RS. HST observations of hydroxyl (OH) are re-analyzed and display a distribution half as broad as that of oxygen, also centered at 4RS. The observed atomic oxygen distribution requires a sourcing of 1.3×1028atomss-1 against loss due to charge capture with the plasma. Using the ion partitioning of Schippers et al. [2008. Multi-instrument analysis of electron populations in Saturn's magnetosphere. Journal of Geophysical Research (Space Physics) 113 (A12) 7208-+] then recombination of H2O+ and H3O+ will account for about a quarter of the mass-loss in the inner magnetosphere, with charge capture of O+ accounting for the rest. The oxygen loss rate is seen to vary by 2×1027atomss-1 over periods of weeks.

Skin dose mapping for non-uniform x-ray fields using a backscatter point spread function

NASA Astrophysics Data System (ADS)

Vijayan, Sarath; Xiong, Zhenyu; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

2017-03-01

Beam shaping devices like ROI attenuators and compensation filters modulate the intensity distribution of the xray beam incident on the patient. This results in a spatial variation of skin dose due to the variation of primary radiation and also a variation in backscattered radiation from the patient. To determine the backscatter component, backscatter point spread functions (PSF) are generated using EGS Monte-Carlo software. For this study, PSF's were determined by simulating a 1 mm beam incident on the lateral surface of an anthropomorphic head phantom and a 20 cm thick PMMA block phantom. The backscatter PSF's for the head phantom and PMMA phantom are curve fit with a Lorentzian function after being normalized to the primary dose intensity (PSFn). PSFn is convolved with the primary dose distribution to generate the scatter dose distribution, which is added to the primary to obtain the total dose distribution. The backscatter convolution technique is incorporated in the dose tracking system (DTS), which tracks skin dose during fluoroscopic procedures and provides a color map of the dose distribution on a 3D patient graphic model. A convolution technique is developed for the backscatter dose determination for the nonuniformly spaced graphic-model surface vertices. A Gafchromic film validation was performed for shaped x-ray beams generated with an ROI attenuator and with two compensation filters inserted into the field. The total dose distribution calculated by the backscatter convolution technique closely agreed with that measured with the film.

The contribution of reserves and anthropogenic habitat for functional connectivity and resilience of ephemeral wetland networks

NASA Astrophysics Data System (ADS)

Allen, C. R.; Uden, D.; Angeler, D.; Hellman, M.

2015-12-01

Functional connectivity of reserves and other suitable habitat patches is crucial for persistence of spatially structured populations, and therefore for resilience. To maintain or increase connectivity at spatial scales larger than individual patches, conservation actions may focus on creating and maintaining reserves or influencing management actions taken on non-reserves. We assess functional connectivity of isolated wetlands within an intensively managed agricultural matrix. Using a graph-theoretic approach, we assessed the functional connectivity and spatial distribution of wetlands in the Rainwater Basins, Nebraska, U.S.A. at four assumed anuran dispersal distances. We compare the contemporary wetlands landscape to the historical landscape and putative future landscapes and evaluate the importance of individual and aggregated reserve and non-reserve wetlands for maintaining connectivity. Connectivity was greatest in the historical landscape, where wetlands were also the most densely distributed. The construction of irrigation reuse pits for water storage has substantially increased connectivity in the current landscape, but because their distribution is more uniform than historical wetlands, larger and longer-dispersing species may be favored over smaller, shorter-dispersing species. Because of their relatively low number, wetland reserves did not affect connectivity as greatly as non-reserve wetlands or irrigation reuse pits; however, they provide the highest-quality anuran habitat. Future levels of connectivity in the region will be directly impacted by the planned removal of irrigation reuse pits, and on non-reserve wetlands. Multi-scale spatial and temporal assessments of the effects of landuse change and conservation actions on landscape connectivity may be used to direct and prioritize conservation actions, and should also be useful for reserve network and landscape resilience assessments.

A Spatial Allocation Procedure to Downscale Regional Crop Production Estimates from an Integrated Assessment Model

NASA Astrophysics Data System (ADS)

Moulds, S.; Djordjevic, S.; Savic, D.

2017-12-01

The Global Change Assessment Model (GCAM), an integrated assessment model, provides insight into the interactions and feedbacks between physical and human systems. The land system component of GCAM, which simulates land use activities and the production of major crops, produces output at the subregional level which must be spatially downscaled in order to use with gridded impact assessment models. However, existing downscaling routines typically consider cropland as a homogeneous class and do not provide information about land use intensity or specific management practices such as irrigation and multiple cropping. This paper presents a spatial allocation procedure to downscale crop production data from GCAM to a spatial grid, producing a time series of maps which show the spatial distribution of specific crops (e.g. rice, wheat, maize) at four input levels (subsistence, low input rainfed, high input rainfed and high input irrigated). The model algorithm is constrained by available cropland at each time point and therefore implicitly balances extensification and intensification processes in order to meet global food demand. It utilises a stochastic approach such that an increase in production of a particular crop is more likely to occur in grid cells with a high biophysical suitability and neighbourhood influence, while a fall in production will occur more often in cells with lower suitability. User-supplied rules define the order in which specific crops are downscaled as well as allowable transitions. A regional case study demonstrates the ability of the model to reproduce historical trends in India by comparing the model output with district-level agricultural inventory data. Lastly, the model is used to predict the spatial distribution of crops globally under various GCAM scenarios.

Modeling pluvial flooding damage in urban environments: spatial relationships between citizens' complaints and overland catchment areas

NASA Astrophysics Data System (ADS)

Gaitan, Santiago; ten Veldhuis, Marie-Claire; van de Giesen, Nick

2013-04-01

Extreme weather events such as floods and storms are expected to cause severe economic losses in The Netherlands. Cumulative damage due to pluvial flooding can be considerable, especially in lowland areas where this type of floods occurs relatively frequently. Currently, in The Netherlands, water-related damages to property and contents are covered through private insurance. As pluvial flooding is becoming heavier and more likely to occur, sound modelling of damages is required to ensure that insurance systems are able to stand as an adaptation measure. Current damage models based on rainfall intensity, registries of insurance claims, and classifications of building types are unable to fully explain damage variability. Further developments assessing additional explanatory factors and reducing uncertainties, are required in order to significantly explain damage. In this study, urban topography is used as an explanatory factor for modelling of urban pluvial flooding. Flood damage is evaluated based on complaints data, a valuable resource for assessing vulnerability to urban pluvial flooding. Though previous research has shown coincidences between the localization of high complaint counts and large size catchments areas in Rotterdam, additional research is needed to establish the precise spatial relationship of those two variables. This additional task is the focus of the presented work. To that end a data base of complaints, that was made available by the Municipality Administration of the City, will be analysed. It comprises close to 36800 complaints from 2004 to 2011. The geographical position of the registries is aggregated into 4 to 6-digit Postal Code zones, which represents entire streets or relative positions along a street, respectively. The Municipality also provided the DEM, characterized by a spatial resolution of 0.5 m × 0.5 m, a vertical precision of 5 cm, and an accuracy better than two standard deviations of 15 cm. First the localization of complaints will be tested for spatial randomness: the distribution of Global Moran's I will be used as a measure of spatial aggregation of complaints. We expect high values of spatial aggregation, that would confirm the existence of a spatial structure in the distribution of complaints. Then we will probe how much does the extent of catchment areas influence such distribution of complaints. That will be done through both an ordinary least squares regression and a geographically weighted regression. By contrasting the results from these two regressions, the relationship between complaints and size of catchment area across the urban environment will be evaluated. The results will confirm whether complaints have a spatial distribution pattern. Furthermore, the results will provide insight into the importance of the size of catchment areas as a significant factor for complaints distribution, and for the assessment of urban vulnerability to pluvial flooding in the City of Rotterdam.

Partitioning into hazard subregions for regional peaks-over-threshold modeling of heavy precipitation

NASA Astrophysics Data System (ADS)

Carreau, J.; Naveau, P.; Neppel, L.

2017-05-01

The French Mediterranean is subject to intense precipitation events occurring mostly in autumn. These can potentially cause flash floods, the main natural danger in the area. The distribution of these events follows specific spatial patterns, i.e., some sites are more likely to be affected than others. The peaks-over-threshold approach consists in modeling extremes, such as heavy precipitation, by the generalized Pareto (GP) distribution. The shape parameter of the GP controls the probability of extreme events and can be related to the hazard level of a given site. When interpolating across a region, the shape parameter should reproduce the observed spatial patterns of the probability of heavy precipitation. However, the shape parameter estimators have high uncertainty which might hide the underlying spatial variability. As a compromise, we choose to let the shape parameter vary in a moderate fashion. More precisely, we assume that the region of interest can be partitioned into subregions with constant hazard level. We formalize the model as a conditional mixture of GP distributions. We develop a two-step inference strategy based on probability weighted moments and put forward a cross-validation procedure to select the number of subregions. A synthetic data study reveals that the inference strategy is consistent and not very sensitive to the selected number of subregions. An application on daily precipitation data from the French Mediterranean shows that the conditional mixture of GPs outperforms two interpolation approaches (with constant or smoothly varying shape parameter).

A Centimeter-Scale Investigation of Geochemical Hotspots in a Soil Lysimeter

NASA Astrophysics Data System (ADS)

Umanzor, M.; Wang, Y.; Dontsova, K.; Chorover, J.; Troch, P. A. A.

2016-12-01

Studying the co-evolution of hydrological and biogeochemical processes in the subsurface of natural landscapes can enhance the understanding of coupled Earth-system processes. Such knowledge is imperative for improving predictions of hydro-biogeochemical cycles, especially under climate change scenarios. Hotspots may form in porous media that is undergoing biogeochemical weathering at locations where reactants accumulate to threshold values along hydrologic flow paths. This is expected to occur in weatherable silicate media, like granular basalt. To examine such processes during incipient soil formation, we constructed a sloping weighing lysimeter 2-m in length, 0.5-m in width and 1-m in depth. Mini-LEO was filled with crushed granular basalt rock with a known initial chemical composition. After 18 months of irrigation and intensive hydrological study, the model "landscape" was divided into a 3D matrix of 324 voxels and excavated. Collected samples were subjected to detailed hydro-bio-geochemical analysis to assess the formation of geochemical heterogeneity. A five-step sequential extraction was employed to characterize incongruent mineral weathering, and its relation to the spatial distribution of microbial composition (in a related study). The changes in Fe and Mn concentration and speciation along the lysimeter length and depth (as measured by each step of the sequential extraction) was quantified to characterize spatial distribution of weathering processes. Results are being used to assist in understanding not only spatial and temporal distribution of basalt weathering on the slope, but also, connections between hydrological and biogeochemical cycles that lead to formation of hotspots.

Effects of Spatial Patch Arrangement and Scale of Covarying Resources on Growth and Intraspecific Competition of a Clonal Plant

PubMed Central

Wang, Yong-Jian; Shi, Xue-Ping; Meng, Xue-Feng; Wu, Xiao-Jing; Luo, Fang-Li; Yu, Fei-Hai

2016-01-01

Spatial heterogeneity in two co-variable resources such as light and water availability is common and can affect the growth of clonal plants. Several studies have tested effects of spatial heterogeneity in the supply of a single resource on competitive interactions of plants, but none has examined those of heterogeneous distribution of two co-variable resources. In a greenhouse experiment, we grew one (without intraspecific competition) or nine isolated ramets (with competition) of a rhizomatous herb Iris japonica under a homogeneous environment and four heterogeneous environments differing in patch arrangement (reciprocal and parallel patchiness of light and soil water) and patch scale (large and small patches of light and water). Intraspecific competition significantly decreased the growth of I. japonica, but at the whole container level there were no significant interaction effects of competition by spatial heterogeneity or significant effect of heterogeneity on competitive intensity. Irrespective of competition, the growth of I. japonica in the high and the low water patches did not differ significantly in the homogeneous treatments, but it was significantly larger in the high than in the low water patches in the heterogeneous treatments with large patches. For the heterogeneous treatments with small patches, the growth of I. japonica was significantly larger in the high than in the low water patches in the presence of competition, but such an effect was not significant in the absence of competition. Furthermore, patch arrangement and patch scale significantly affected competitive intensity at the patch level. Therefore, spatial heterogeneity in light and water supply can alter intraspecific competition at the patch level and such effects depend on patch arrangement and patch scale. PMID:27375630