WorldWideScience

Sample records for void space created

  1. Redshift-space distortions around voids

    Science.gov (United States)

    Cai, Yan-Chuan; Taylor, Andy; Peacock, John A.; Padilla, Nelson

    2016-11-01

    We have derived estimators for the linear growth rate of density fluctuations using the cross-correlation function (CCF) of voids and haloes in redshift space. In linear theory, this CCF contains only monopole and quadrupole terms. At scales greater than the void radius, linear theory is a good match to voids traced out by haloes; small-scale random velocities are unimportant at these radii, only tending to cause small and often negligible elongation of the CCF near its origin. By extracting the monopole and quadrupole from the CCF, we measure the linear growth rate without prior knowledge of the void profile or velocity dispersion. We recover the linear growth parameter β to 9 per cent precision from an effective volume of 3( h-1Gpc)3 using voids with radius >25 h-1Mpc. Smaller voids are predominantly sub-voids, which may be more sensitive to the random velocity dispersion; they introduce noise and do not help to improve measurements. Adding velocity dispersion as a free parameter allows us to use information at radii as small as half of the void radius. The precision on β is reduced to 5 per cent. Voids show diverse shapes in redshift space, and can appear either elongated or flattened along the line of sight. This can be explained by the competing amplitudes of the local density contrast, plus the radial velocity profile and its gradient. The distortion pattern is therefore determined solely by the void profile and is different for void-in-cloud and void-in-void. This diversity of redshift-space void morphology complicates measurements of the Alcock-Paczynski effect using voids.

  2. Redshift-space distortions around voids

    CERN Document Server

    Cai, Yan-Chuan; Peacock, John A; Padilla, Nelson

    2016-01-01

    We have derived estimators for the linear growth rate of density fluctuations using the cross-correlation function of voids and haloes in redshift space, both directly and in Fourier form. In linear theory, this cross-correlation contains only monopole and quadrupole terms. At scales greater than the void radius, linear theory is a good match to voids traced out by haloes in N-body simulations; small-scale random velocities are unimportant at these radii, only tending to cause small and often negligible elongation of the redshift-space cross-correlation function near its origin. By extracting the monopole and quadrupole from the cross-correlation function, we measure the linear growth rate without prior knowledge of the void profile or velocity dispersion. We recover the linear growth parameter $\\beta$ to 9% precision from an effective volume of 3(Gpc/h)^3 using voids with radius greater than 25Mpc/h. Smaller voids are predominantly sub-voids, which may be more sensitive to the random velocity dispersion; the...

  3. 46 CFR 154.1210 - Hold space, void space, cofferdam, and spaces containing cargo piping.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Hold space, void space, cofferdam, and spaces containing... Design, Construction and Equipment Cargo Area: Mechanical Ventilation System § 154.1210 Hold space, void space, cofferdam, and spaces containing cargo piping. (a) Each hold space, void space, cofferdam,...

  4. Creating new market space.

    Science.gov (United States)

    Kim, W C; Mauborgne, R

    1999-01-01

    Most companies focus on matching and beating their rivals. As a result, their strategies tend to take on similar dimensions. What ensues is head-to-head competition based largely on incremental improvements in cost, quality, or both. The authors have studied how innovative companies break free from the competitive pack by staking out fundamentally new market space--that is, by creating products or services for which there are no direct competitors. This path to value innovation requires a different competitive mind-set and a systematic way of looking for opportunities. Instead of looking within the conventional boundaries that define how an industry competes, managers can look methodically across them. By so doing, they can find unoccupied territory that represents real value innovation. Rather than looking at competitors within their own industry, for example, managers can ask why customers make the trade-off between substitute products or services. Home Depot, for example, looked across the substitutes serving home improvement needs. Intuit looked across the substitutes available to individuals managing their personal finances. In both cases, powerful insights were derived from looking at familiar data from a new perspective. Similar insights can be gleaned by looking across strategic groups within an industry; across buyer groups; across complementary product and service offerings; across the functional-emotional orientation of an industry; and even across time. To help readers explore new market space systematically, the authors developed a tool, the value curve, that can be used to represent visually a range of value propositions.

  5. Linear redshift space distortions for cosmic voids based on galaxies in redshift space

    CERN Document Server

    Chuang, Chia-Hsun; Liang, Yu; Font-Ribera, Andreu; Zhao, Cheng; McDonald, Patrick; Tao, Charling

    2016-01-01

    Cosmic voids found in galaxy surveys are defined based on the galaxy distribution in redshift space. We show that the large scale distribution of voids in redshift space traces the fluctuations in the dark matter density field \\delta(k) (in Fourier space with \\mu being the line of sight projected k-vector): \\delta_v^s(k) = (1 + \\beta_v \\mu^2) b^s_v \\delta(k), with a beta factor that will be in general different than the one describing the distribution of galaxies. Only in case voids could be assumed to be quasi-local transformations of the linear (Gaussian) galaxy redshift space field, one gets equal beta factors \\beta_v=\\beta_g=f/b_g with f being the growth rate, and b_g, b^s_v being the galaxy and void bias on large scales defined in redshift space. Indeed, in our mock void catalogs we measure void beta factors being in good agreement with the galaxy one. Further work needs to be done to confirm the level of accuracy of the beta factor equality between voids and galaxies, but in general the void beta factor...

  6. Multipole analysis of redshift-space distortions around cosmic voids

    Science.gov (United States)

    Hamaus, Nico; Cousinou, Marie-Claude; Pisani, Alice; Aubert, Marie; Escoffier, Stéphanie; Weller, Jochen

    2017-07-01

    We perform a comprehensive redshift-space distortion analysis based on cosmic voids in the large-scale distribution of galaxies observed with the Sloan Digital Sky Survey. To this end, we measure multipoles of the void-galaxy cross-correlation function and compare them with standard model predictions in cosmology. Merely considering linear-order theory allows us to accurately describe the data on the entire available range of scales and to probe void-centric distances down to about 2 h-1Mpc. Common systematics, such as the Fingers-of-God effect, scale-dependent galaxy bias, and nonlinear clustering do not seem to play a significant role in our analysis. We constrain the growth rate of structure via the redshift-space distortion parameter β at two median redshifts, β(bar z=0.32)=0.599+0.134-0.124 and β(bar z=0.54)=0.457+0.056-0.054, with a precision that is competitive with state-of-the-art galaxy-clustering results. While the high-redshift constraint perfectly agrees with model expectations, we observe a mild 2σ deviation at bar z=0.32, which increases to 3σ when the data is restricted to the lowest available redshift range of 0.15

  7. Dynamical 3-Space: Cosmic Filaments, Sheets and Voids

    Directory of Open Access Journals (Sweden)

    Cahill R. T.

    2011-04-01

    Full Text Available Observations of weak gravitational lensing combined with statistical tomographic techniques have revealed that galaxies have formed along filaments, essentially one- dimensional lines or strings, which form sheets and voids. These have, in the main, been interpreted as “dark matter” effects. To the contrary here we report the discovery that the dynamical 3-space theory possesses such filamentary solutions. These solutions are purely space self-interaction effects, and are attractive to matter, and as well gener- ate electromagnetic lensing. This theory of space has explained bore hole anomalies, supermassive black hole masses in spherical galaxies and globular clusters, flat rota- tion curves of spiral galaxies, and other gravitational anomalies. The theory has two constants, G and , where the bore hole experiments show that 1 = 137 is the fine structure constant.

  8. Exploring light extraction efficiency of InGaN LED by creating structured voids in substrate with a femtosecond laser

    Science.gov (United States)

    Wu, Shih-jeh; Tseng, Chun-Lung; Lu, Tsung-Sheng; Chen, Ying-Chieh; Tseng, Pei-Hsiang

    2017-02-01

    The applications of laser in processing of light-emitting diodes (LEDs) have become popular and inevitable. In this paper, we reported a complete fabrication process of InGaN LED involving a small modification of substrate by ultrafast laser. We created structured voids within the pattern sapphire substrate (PSS) with distributed Bragg reflector (DBR) on the backside by a tightly focused femtosecond laser. One or two passes of voids were aligned in rectangular grid shape and a study of different grid spacing was conducted. The wafers were stealth-diced by the same laser and mechanically cleaved after the on-wafer light output powers (LOP) are measured at 120 mA nominal current. The splitted chips are then undergone complete packaging process and LOP is measured again along with the electrical and irradiation properties. A raise of 1.35% of average on-wafer LOP is achieved at the optimal condition: 0.2 W total laser power for two passes of voids (grid spacing 40 μm) at focal depths set at 32 μm and 64 μm respectively from the backside. Also, the illumination efficiency is further improved by 4.59% after epoxy molding compound (EMC) packaging. The voids serve successfully as scattering or diffractive sources to reverse the stray photons in useful directions. Apart from the enhancement from both PSS and DBR there is still room for light extraction efficiency (LEE) improvement. The L-I-V relationship and diffusion angle are also presented.

  9. Creating Space for Children's Literature

    Science.gov (United States)

    Serafini, Frank

    2011-01-01

    As teachers struggle to balance the needs of their students with the requirements of commercial reading materials, educators need to consider how teachers will create space for children's literature in today's classrooms. In this article, 10 practical recommendations for incorporating children's literature in the reading instructional framework…

  10. Glass composition and process for sealing void spaces in electrochemical devices

    Science.gov (United States)

    Meinhardt, Kerry D.; Kirby, Brent W.

    2012-05-01

    A glass foaming material and method are disclosed for filling void spaces in electrochemical devices. The glass material includes a reagent that foams at a temperature above the softening point of the glass. Expansion of the glass fills void spaces including by-pass and tolerance channels of electrochemical devices. In addition, cassette to cassette seals can also be formed while channels and other void spaces are filled, reducing the number of processing steps needed.

  11. Void Dynamics

    Science.gov (United States)

    Padilla, Nelson D.; Paz, Dante; Lares, Marcelo; Ceccarelli, Laura; Lambas, Diego Garcí A.; Cai, Yan-Chuan; Li, Baojiu

    2016-10-01

    Cosmic voids are becoming key players in testing the physics of our Universe.Here we concentrate on the abundances and the dynamics of voids as these are among the best candidatesto provide information on cosmological parameters. Cai, Padilla & Li (2014)use the abundance of voids to tell apart Hu & Sawicki f(R) models from General Relativity. An interestingresult is that even though, as expected, voids in the dark matter field are emptier in f(R) gravity due to the fifth force expellingaway from the void centres, this result is reversed when haloes are used to find voids. The abundance of voids in this casebecomes even lower in f(R) compared to GR for large voids. Still, the differences are significant and thisprovides a way to tell apart these models. The velocity field differences between f(R) and GR, on the other hand, arethe same for halo voids and for dark matter voids.Paz et al. (2013), concentrate on the velocity profiles around voids. First they show the necessityof four parameters to describe the density profiles around voids given two distinct voidpopulations, voids-in-voids and voids-in-clouds. This profile is used to predict peculiar velocities around voids,and the combination of the latter with void density profiles allows the construction of modelvoid-galaxy cross-correlation functions with redshift space distortions. When these modelsare tuned to fit the measured correlation functions for voids and galaxies in the SloanDigital Sky Survey, small voids are found to be of the void-in-cloud type, whereas largerones are consistent with being void-in-void. This is a novel result that is obtaineddirectly from redshift space data around voids. These profiles can be used toremove systematics on void-galaxy Alcock-Pacinsky tests coming from redshift-space distortions.

  12. Void space structure in carbonate deposits of the Voronezh Horizon in the Pripyat trough

    Energy Technology Data Exchange (ETDEWEB)

    Kazenkina, G.A.; Demidovich, L.A.

    1977-05-01

    Change characteristics in void space were identified by studying the void space of carbonate rock-collectors on model-counterparts and by petrographic studies. The rock in the anticline sections of local structures have the most complex structure. Mixed types of collectors predominate here. 1 table, 2 figures, 2 references.

  13. Probing cosmology and gravity with redshift-space distortions around voids

    CERN Document Server

    Hamaus, Nico; Lavaux, Guilhem; Wandelt, Benjamin D

    2015-01-01

    Cosmic voids in the large-scale structure of the Universe affect the peculiar motions of objects in their vicinity. Although these motions are difficult to observe directly, the clustering pattern of their surrounding tracers in redshift space is influenced in a unique way. This allows to investigate the interplay between densities and velocities around voids, which is solely dictated by the laws of gravity. With the help of N-body simulations and derived mock-galaxy catalogs we calculate the average density fluctuations inside and outside voids identified with a watershed algorithm in redshift space and compare the results with the expectation from general relativity and the LCDM model of cosmology. We find that simple linear-theory predictions work remarkably well in describing the dynamics of voids even on relatively small scales. Adopting a Bayesian inference framework, we determine the full posterior probability distribution of our model parameters and forecast the achievable accuracy on measurements of ...

  14. The Iconic Chora: A Space of Kenotic Presence and Void

    DEFF Research Database (Denmark)

    Isar, Nicoletta

    2000-01-01

    and a cognitive theory that have proved incapable of explaining the endurance of the Byzantine scheme of the icon and of its oxymoronic (paradoxical) definition, except through an appeal to primitivism. I will attempt to put forward an alternative reading of the iconic space and show how vision itself...... is transfigured through participation. My thesis is that the icon belongs to another order of cognitive apprehension. It resists Kantian logic or any other categories of modern cognition. The paradoxical play between presence and absence in the definition of the iconic space is founded on a theology of kenôsis...

  15. Creating Safe Spaces for Music Learning

    Science.gov (United States)

    Hendricks, Karin S.; Smith, Tawnya D.; Stanuch, Jennifer

    2014-01-01

    This article offers a practical model for fostering emotionally safe learning environments that instill in music students a positive sense of self-belief, freedom, and purpose. The authors examine the implications for music educators of creating effective learning environments and present recommendations for creating a safe space for learning,…

  16. The Iconic Chora: A Space of Kenotic Presence and Void

    DEFF Research Database (Denmark)

    Isar, Nicoletta

    2000-01-01

      The purpose of this essay is not exhaustive research concerning the iconic space and vision in Byzantium. Rather, the aim is to reshuffle the texts - from theological statements in defense of the image to liturgical, living ritual - to build up a polemical discourse with a tradition....... Presence and absence, emptiness and fullness, are both "foiled" and transfigured in the icon - a theological and a doctrinal statement in its essence....

  17. Influence of void space on microscopic behavior of fluid flow in rock joints

    Institute of Scientific and Technical Information of China (English)

    Zhang Zhenyu; Jan Nemcik; Ren Ting; Zhang Jun

    2014-01-01

    Advanced microfluidic technology was used to examine the microscopic viscous and inertial effects evo-lution of water flow in rock joints. The influence of void space on fluid flow behaviour in rock joints under different flow velocities was experimentally investigated at the micro scale. Using advanced fabrication technology of microfluidic device, micro flow channels of semicircular, triangular, rectangular and pentagonal cavities were fabricated to simulate different void space of rock joints, respectively. Using the fluorescence labelling approach, the trajectory of water flow was captured by the microscope digital camera when it passed over the cavity under different flow velocities. The flow tests show that the flow trajectory deviated towards the inside of the cavity at low flow velocities. With the increase in flow veloc-ity, this degree of flow trajectory deviation decreased until there was no trajectory deviation for flow in the straight parallel channel. The flow trajectory deviation initially reduced from the void corner near the entrance. At the same time, a small eddy appeared near the void corner of the entrance. The size and intensity of the eddy increased with the flow velocity until it occupied the whole cavity domain. The gradual reduction of flow trajectory near the straight parallel channel and the growth of eddy inside the cavity reflect the evolution of microscopic viscous and inertial forces under different flow velocities. The eddy formed inside the cavity does not contribute to the total flow flux, but the running of the eddy consumes flow energy. This amount of pressure loss due to voids could contribute to the nonlinear devi-ation of fracture fluid flow from Darcy’s law. This study contributes to the fundamental understanding of non-Darcy’s flow occurrence in rock joints at the micro scale.

  18. Creating Spaces to Support Transgender Youth

    Science.gov (United States)

    McGuire, Jenifer K.; Conover-Williams, Meredith

    2010-01-01

    This article explores the opportunity to create spaces within the family, school, and community that specifically promote the well-being of transgender adolescents and young adults. When social contexts are supportive, transgender youth report significantly less risk. Supportive home and school environments have been linked to better outcomes…

  19. Role of void space geometry in permeability evolution in crustal rocks at elevated pressure

    Science.gov (United States)

    Benson, Philip M.; Meredith, Philip G.; Schubnel, Alexandre

    2006-12-01

    A key consequence of the presence of void space within rock is their significant influence upon fluid transport properties. In this study, we measure changes in elastic wave velocities (P and S) contemporaneously with changes in permeability and porosity at elevated pressure for three rock types with widely different void space geometries: a high-porosity sandstone (Bentheim), a tight sandstone (Crab Orchard), and a microcracked granodiorite (Takidani). Laboratory data are then used with the permeability models of Guéguen and Dienes and Kozeny-Carman to investigate the characteristics that different void space geometries impart to measured permeabilities. Using the Kachanov effective medium theory, elastic wave velocities are inverted, permitting the recovery of crack density evolution with increasing effective pressure. The crack densities are then used as input to the microcrack permeability model of Guéguen and Dienes. The classic Kozeny-Carman approach of Walsh and Brace is also applied to the measured permeability data via a least squares fit in order to extract tortuosity data. We successfully predict the evolution of permeability with increasing effective pressure, as directly measured in experiments, and report the contrast between permeability changes observed in rock where microcracks or equant pores dominate the microstructure. Additionally, we show how these properties are affected by anisotropy of the rock types via the measured anisotropic fabrics in each rock. The combined experimental and modeling results illustrate the importance of understanding the details of how rock microstructure changes in response to an external stimulus in predicting the simultaneous evolution of different rock physical properties.

  20. Refractometric discrimination of void-space filling and swelling during vapour sorption in polymer films.

    Science.gov (United States)

    Cross, G H; Ren, Y; Swann, M J

    2000-12-01

    Thin polymeric films have been deposited as upper cladding layers on a new integrated optical interferometer fabricated from layers of silicon oxynitride on a silicon wafer. The evanescent field of the probing waveguide mode transduces refractive index changes in the polymer layer into the measured phase changes in the device. Real-time measurement of index change and its sign is obtained. Upon exposure to humid air, we record water sorption by films of poly(vinyl pyrrolidone) by a rapid positive index change for void-space filling followed by a slow negative index change for swelling. Sorption of water vapor into a thin film of the viscous liquid polymer polyethylenimine shows only swelling mode behaviour and a simple constitutive model can be applied to give the fractional water occupied volume.

  1. Institutional Ethics Resources: Creating Moral Spaces.

    Science.gov (United States)

    Hamric, Ann B; Wocial, Lucia D

    2016-09-01

    Since 1992, institutions accredited by The Joint Commission have been required to have a process in place that allows staff members, patients, and families to address ethical issues or issues prone to conflict. While the commission's expectations clearly have made ethics committees more common, simply having a committee in no way demonstrates its effectiveness in terms of the availability of the service to key constituents, the quality of the processes used, or the outcomes achieved. Beyond meeting baseline accreditation standards, effective ethics resources are requisite for quality care for another reason. The provision of care to the sick is a practice with profound moral dimensions. Clinicians need what Margaret Urban Walker has called "moral spaces," reflective spaces within institutions in which to explore and communicate values and ethical obligations as they undergird goals of care. Walker proposed that ethicists needed to be concerned with the design and maintenance of these moral spaces. Clearly, that concern needs to extend beyond ethicists to institutional leaders. This essay uses Walker's idea of moral space to describe individuals and groups who are actual and potential ethics resources in health care institutions. We focus on four requisite characteristics of effective resources and the challenges to achieving them, and we identify strategies to build them. In our view, such moral spaces are particularly important for nurses and their colleagues on interprofessional teams and need to be expanded and strengthened in most settings.

  2. Creating a sense of auditory space

    OpenAIRE

    McAlpine, D

    2005-01-01

    Determining the location of a sound source requires the use of binaural hearing - information about a sound at the two ears converges onto neurones in the auditory brainstem to create a binaural representation. The main binaural cue used by many mammals to locate a sound source is the interaural time difference, or ITD. For over 50 years a single model has dominated thinking on how ITDs are processed. The Jeffress model consists of an array of coincidence detectors binaural neurones that resp...

  3. Creating a sense of auditory space.

    Science.gov (United States)

    McAlpine, David

    2005-07-01

    Determining the location of a sound source requires the use of binaural hearing--information about a sound at the two ears converges onto neurones in the auditory brainstem to create a binaural representation. The main binaural cue used by many mammals to locate a sound source is the interaural time difference, or ITD. For over 50 years a single model has dominated thinking on how ITDs are processed. The Jeffress model consists of an array of coincidence detectors--binaural neurones that respond maximally to simultaneous input from each ear--innervated by a series of delay lines--axons of varying length from the two ears. The purpose of this arrangement is to create a topographic map of ITD, and hence spatial position in the horizontal plane, from the relative timing of a sound at the two ears. This model appears to be realized in the brain of the barn owl, an auditory specialist, and has been assumed to hold for mammals also. Recent investigations, however, indicate that both the means by which neural tuning for preferred ITD, and the coding strategy used by mammals to determine the location of a sound source, may be very different to barn owls and to the model proposed by Jeffress.

  4. Nuts and Bolts for Creating Space

    CERN Document Server

    Czech, Bartlomiej

    2014-01-01

    We discuss the way in which field theory quantities assemble the spatial geometry of three-dimensional anti-de Sitter space (AdS3). The field theory ingredients are the entanglement entropies of boundary intervals. A point in AdS3 corresponds to a collection of boundary intervals, which is selected by a variational principle we discuss. Coordinates in AdS3 are integration constants of the resulting equation of motion. We propose a distance function for this collection of points, which obeys the triangle inequality as a consequence of the strong subadditivity of entropy. Our construction correctly reproduces the static slice of AdS3 and the Ryu-Takayanagi relation between geodesics and entanglement entropies. We discuss how these results extend to quotients of AdS3 -- the conical defect and the BTZ geometries. In these cases, the set of entanglement entropies must be supplemented by other field theory quantities, which can carry the information about lengths of non-minimal geodesics.

  5. Modeling cosmic void statistics

    Science.gov (United States)

    Hamaus, Nico; Sutter, P. M.; Wandelt, Benjamin D.

    2016-10-01

    Understanding the internal structure and spatial distribution of cosmic voids is crucial when considering them as probes of cosmology. We present recent advances in modeling void density- and velocity-profiles in real space, as well as void two-point statistics in redshift space, by examining voids identified via the watershed transform in state-of-the-art ΛCDM n-body simulations and mock galaxy catalogs. The simple and universal characteristics that emerge from these statistics indicate the self-similarity of large-scale structure and suggest cosmic voids to be among the most pristine objects to consider for future studies on the nature of dark energy, dark matter and modified gravity.

  6. Experimental study of void space, permeability and elastic anisotropy in crustal rocks under ambient and hydrostatic pressure

    Science.gov (United States)

    Benson, Philip Michael

    Anisotropy in the physical and transport properties of crustal rocks is a key influence on crustal evolution and energy resource management. Data from deep seismic soundings, borehole logging and laboratory measurement all show that the physical properties of the earth are anisotropic. Such anisotropy generally results from the superposition of fabric development during diagenesis and/or petrogenesis, and the application of anisotropic tectonic stresses. This leads to an aligned crack and pore fabric in crustal rocks that, in turn, leads to seismic velocity anisotropy and permeability anisotropy. This thesis describes an experimental study which aims to investigate the relationships between pressure, pore fabric geometry and seismic and permeability anisotropy under hydrostatic pressures from room pressure to ~4km depth equivalence within the Earth's crust. Firstly, pore fabric analyses of three representative crustal rock types is presented. These rock types represent a range of crack and pore fabrics. The average void space shape and orientation is determined 3-D using the methods of anisotropy of magnetic susceptibility and velocity anisotropy. Scanning electron microscopy and fluorescent-dye crack imaging techniques further aid in the void space characterisation. Secondly, the development and application of an apparatus capable of contemporaneously measuring elastic wave velocity, porosity and permeability at effective pressures of up to 100 MPa is described. Results are analysed in terms of applied effective pressure and the rock pore fabric type and orientation. Finally, the laboratory data are used to test models that attempt to predict geophysical parameters such as permeability and elastic wave velocity from microstructural attributes. This multi-facetted analysis allows a number of conclusions to be drawn, expanding the state-of-the-art in how the pore fabric microstructure of crustal rock is represented by the methods of elastic wave velocity and

  7. Draining the Local Void

    CERN Document Server

    Rizzi, Luca; Shaya, Edward J; Kourkchi, Ehsan; Karachentsev, Igor D

    2016-01-01

    Two galaxies that lie deep within the Local Void provide a test of the expectation that voids expand. The modest (M_B~-14) HI bearing dwarf galaxies ALFAZOAJ1952+1428 and KK246 have been imaged with Hubble Space Telescope in order to study the stellar populations and determine distances from the luminosities of stars at the tip of the red giant branch. The mixed age systems have respective distances of 8.39 Mpc and 6.95 Mpc and inferred line-of-sight peculiar velocities of -114 km/s and -66 km/s toward us and away from the void center. These motions compound on the Milky Way motion of ~230 km/s away from the void. The orbits of the two galaxies are reasonably constrained by a numerical action model encompassing an extensive region that embraces the Local Void. It is unambiguously confirmed that these two void galaxies are moving away from the void center at several hundred km/s.

  8. On cavitation instabilities with interacting voids

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2012-01-01

    voids so far apart that the radius of the plastic zone around each void is less than 1% of the current spacing between the voids, can still affect each others at the occurrence of a cavitation instability such that one void stops growing while the other grows in an unstable manner. On the other hand...

  9. CREATING URBAN AND BUILDING SPACE FOR AGRICULTURAL SPACE TOWARDS SUSTAINABLE JAKARTA

    Directory of Open Access Journals (Sweden)

    Albertus Galih Prawata

    2013-11-01

    strategies that can help the city, so it can produce its own food and create sustainable lifestyle. This paper focuses on how to create Jakarta, one of the big cities in South East Asia, into a city based on agricultural system that can ensure food safety and make a sustainable urban lifestyle without damaging the environment. Also, it discusses the possibilities of converting the urban or building space into agricultural space, which can support the food production for the people of Jakarta.

  10. Creating Body Shapes From Verbal Descriptions by Linking Similarity Spaces.

    Science.gov (United States)

    Hill, Matthew Q; Streuber, Stephan; Hahn, Carina A; Black, Michael J; O'Toole, Alice J

    2016-11-01

    Brief verbal descriptions of people's bodies (e.g., "curvy," "long-legged") can elicit vivid mental images. The ease with which these mental images are created belies the complexity of three-dimensional body shapes. We explored the relationship between body shapes and body descriptions and showed that a small number of words can be used to generate categorically accurate representations of three-dimensional bodies. The dimensions of body-shape variation that emerged in a language-based similarity space were related to major dimensions of variation computed directly from three-dimensional laser scans of 2,094 bodies. This relationship allowed us to generate three-dimensional models of people in the shape space using only their coordinates on analogous dimensions in the language-based description space. Human descriptions of photographed bodies and their corresponding models matched closely. The natural mapping between the spaces illustrates the role of language as a concise code for body shape that captures perceptually salient global and local body features.

  11. Rogues of the Void : Design process of a space board game

    OpenAIRE

    Heino, Riku

    2014-01-01

    This thesis is about the design process of a space themed board game and board game design theory in general. The question is: do thematic games require some design sacrifices for the sake of gameplay and what are the ways of avoiding doing so. The purpose of this design project is to study these phenomena and prove if these problems are avoidable in general. Secondly, this thesis is meant to introduce board games and their functionalities to readers who are interested in board games and boar...

  12. Responsibility voids

    NARCIS (Netherlands)

    van Hees, M.V.B.P.M; Braham, Matthew

    We present evidence for the existence of 'responsibility voids' in committee decision-making, that is, the existence of situations where no member of a committee can individually be held morally responsible for the outcome. We analyse three types of reasons (causal, normative and epistemic) for the

  13. Generalized network modeling: Network extraction as a coarse-scale discretization of the void space of porous media

    Science.gov (United States)

    Raeini, Ali Q.; Bijeljic, Branko; Blunt, Martin J.

    2017-07-01

    A generalized network extraction workflow is developed for parameterizing three-dimensional (3D) images of porous media. The aim of this workflow is to reduce the uncertainties in conventional network modeling predictions introduced due to the oversimplification of complex pore geometries encountered in natural porous media. The generalized network serves as a coarse discretization of the surface generated from a medial-axis transformation of the 3D image. This discretization divides the void space into individual pores and then subdivides each pore into sub-elements called half-throat connections. Each half-throat connection is further segmented into corners by analyzing the medial axis curves of its axial plane. The parameters approximating each corner—corner angle, volume, and conductivity—are extracted at different discretization levels, corresponding to different wetting layer thickness and local capillary pressures during multiphase flow simulations. Conductivities are calculated using direct single-phase flow simulation so that the network can reproduce the single-phase flow permeability of the underlying image exactly. We first validate the algorithm by using it to discretize synthetic angular pore geometries and show that the network model reproduces the corner angles accurately. We then extract network models from micro-CT images of porous rocks and show that the network extraction preserves macroscopic properties, the permeability and formation factor, and the statistics of the micro-CT images.

  14. Comments on ``The Euclidean gravitational action as black hole entropy, singularities, and space-time voids'' [J. Math. Phys. 49, 042501 (2008)

    Science.gov (United States)

    Mitra, Abhas

    2009-04-01

    We point out that the space-time void inferred by Castro [J. Math. Phys. 49, 042501 (2008)] results from his choice of a discontinuous radial gauge. Further since the integration constant α0=2M0 (G =c=1) occurring in the vacuum Hilbert/Schwarzschild solution of a neutral "point mass" is zero [Arnowitt et al., in Gravitation: An Introduction to Current Research, edited by L. Witten (Wiley, New York, 1962), Chap. 7, p. 227; also Phys. Rev. Lett. 4, 375 (1960). A. Mitra, Adv. Space Res. 38, 2917 (2006); Proceedings of the XIth Marcel-Grossmann Conference on General Relativity (World Scientific, Singapore, 2008), Vol. 3, p. 1968], Castro's gauge reduces to the well behaved and physical Hilbert gauge. Physically this means that true Hilbert/Schwarzschild black holes have unique gravitational mass M =0. Accordingly, the unphysical space-time void inferred by Castro is actually nonexistent.

  15. Creating inter-cultural spaces for co-learning

    Directory of Open Access Journals (Sweden)

    Kristina Everett

    2013-01-01

    Full Text Available Among the many inhibitors to social inclusion and mobility faced by Indigenous peoples in Australia, under-representation of Indigenous students in Higher Education has long featured as a concern for government and human rights advocates. This is due to the attendant lower social indicators than those of the wider Australian society which characterise Indigenous peoples’ life experience. UNESCO’s guidelines on inter-cultural education published in 2007 provide some principles for groundwork to develop classrooms which are inclusive but not assimilationist. Models of how this might be done in practice, however, are scarce. In this paper we consider a model for inter-cultural education which uses joint analysis and dialogue surrounding self-representation of Indigenous peoples by Indigenous and non-Indigenous peers to then co-create a new, inter-cultural representation. The ‘Daruganora’ program involves Indigenous students leading dialogue with nonIndigenous peers and teachers to jointly interpret a purpose-built Indigenous art exhibition. We explain in this paper how spaces created by this dialogue can allow open, honest and respectful interaction between Indigenous and non-Indigenous people relating to Indigenous representations of identity. We argue that Daruganora provides a model for inter-cultural classrooms.

  16. CT measurements of SAP voids in concrete

    DEFF Research Database (Denmark)

    Laustsen, Sara; Bentz, Dale P.; Hasholt, Marianne Tange

    2010-01-01

    X-ray computed tomography (CT) scanning is used to determine the SAP void distribution in hardened concrete. Three different approaches are used to analyse a binary data set created from CT measurement. One approach classifies a cluster of connected, empty voxels (volumetric pixel of a 3D image......) as one void, whereas the other two approaches are able to classify a cluster of connected, empty voxels as a number of individual voids. Superabsorbent polymers (SAP) have been used to incorporate air into concrete. An advantage of using SAP is that it enables control of the amount and size...... of the created air voids. The results indicate the presence of void clusters. To identify the individual voids, special computational approaches are needed. The addition of SAP results in a dominant peak in two of the three air void distributions. Based on the position (void diameter) of the peak, it is possible...

  17. CT measurements of SAP voids in concrete

    DEFF Research Database (Denmark)

    Laustsen, Sara; Bentz, Dale P.; Hasholt, Marianne Tange;

    2010-01-01

    X-ray computed tomography (CT) scanning is used to determine the SAP void distribution in hardened concrete. Three different approaches are used to analyse a binary data set created from CT measurement. One approach classifies a cluster of connected, empty voxels (volumetric pixel of a 3D image......) as one void, whereas the other two approaches are able to classify a cluster of connected, empty voxels as a number of individual voids. Superabsorbent polymers (SAP) have been used to incorporate air into concrete. An advantage of using SAP is that it enables control of the amount and size...... of the created air voids. The results indicate the presence of void clusters. To identify the individual voids, special computational approaches are needed. The addition of SAP results in a dominant peak in two of the three air void distributions. Based on the position (void diameter) of the peak, it is possible...

  18. CU Prime Diversity Workshops: Creating Spaces for Growth Amongst Organizers

    Science.gov (United States)

    Hyater-Adams, Simone

    2016-03-01

    CU Prime is a graduate student run organization that was created as a way to promote community and inclusion amongst students in CU Physics Department. With a mission to improve the experiences of students, especially those underrepresented in the department and field, the core organizers developed three programs: a seminar series, a class, and a mentorship program. However, because this is strictly volunteer time for most organizers, there is little time for development and growth as a group. In response, we developed a series of diversity workshops for the group, in order to provide space and time for organizers to reflect on and grapple with difficult issues around diversity and inclusion that are important to think about when running these programs. With a structure based on readings, informal videos, and reflection, there have been 5 workshops around topics ranging from gender in physics to how to be an ally. We overview the structure and framing of these workshops, along with the challenges and successes throughout the process of developing them, along with plans for future development.

  19. The Beckoning Void in Moravagine

    Directory of Open Access Journals (Sweden)

    Stephen K. Bellstrom

    1979-01-01

    Full Text Available The Chapter «Mascha,» lying at the heart of Cendrars's Moravagine , contains within it a variety of images and themes suggestive of emptiness. The philosophy of nihilism is exemplified in the motivations and actions of the group of terrorists seeking to plunge Russia into revolutionary chaos. Mascha's anatomical orifice, symbolizing both a biological and a psychological fault, and the abortion of her child, paralleled by the abortion of the revolutionary ideal among her comrades, are also emblematic of the chapter's central void. Moreover, Cendrars builds the theme of hollowness by describing Moravagine with images of omission, such as «empan» (space or span, «absent,» and «étranger.» Moravagine's presence, in fact, characteristically causes an undercurrent of doubt and uncertainty about the nature of reality to become overt. It is this parodoxical presence which seems to cause the narrator (and consequently the narrative to «lose» a day at the most critical moment of the story. By plunging the reader into the narrator's lapsus memoriae , Cendrars aims at creating a feeling of the kind of mental and cosmic disorder for which Moravagine is the strategist and apologist. This technique of insufficiency is an active technique, even though it relies on the passive idea of removing explanation and connecting details. The reader is invited, or lured, into the central void of the novel and, faced with unresolvable dilemmas, becomes involved in the same disorder that was initially produced.

  20. A new geometrical approach to void statistics

    CERN Document Server

    Werner, M C

    2014-01-01

    Modelling cosmic voids as spheres in Euclidean space, the notion of a de-Sitter configuration space is introduced. It is shown that a uniform distribution over this configuration space yields a power-law approximating the void size distribution in an intermediate range of volumes, as well as an estimate for the fractal dimension of the large scale structure.

  1. Creating a Public Space through Service-Learning

    Science.gov (United States)

    Brigham, Erin

    2012-01-01

    In this paper, I suggest that community-based learning can act as a "public space" for the exchange of religious and non-religious identities. By providing a space for the collaboration between religiously-affiliated Universities and non-religiously affiliated community partners, community-based learning offers the opportunity for the negotiation…

  2. Children Creating Ways To Represent Changing Situations: On the Development of Homogeneous Spaces.

    Science.gov (United States)

    Nemirovsky, Ricardo; Tierney, Cornelia

    2001-01-01

    Focuses on children creating representations on paper for situations that change over time. Articulates the distinction between homogeneous and heterogeneous spaces and reflects on children's tendency to create hybrids between them. (Author/MM)

  3. Colombia an approach to create a national space agency

    Science.gov (United States)

    Arenales, O.

    Space exploration is a great human adventure: culturally, scientifically, technologically and industrially. Since the earliest of times, civilizations have been united in their awe of, and inspiration by, the cosmos, as testified in particularly by the peoples and cultures of the Central and South American continent in pre- Columbian times. Today, space systems have become an essential tool for the scientific disciplines related to the knowledge of the universe, including our own planet and its close or its remote environment. The main objective of this research is to explain the way in which Colombia, rich in myths and secular legends connecting mankind to the universe, must in the present tackle the issue of its development of space activities. The context in which it could be carried out is also described, along with a perspective of the current state of science and technology in the space sector on a global scale. Any modern nation is concerned with its independence, whether political, economic, or intellectual. That is why we support the concept of countries in the process of development becoming actively involved in the international space scene. Indeed, having limitations in industrial and technological exchange, we feel excluded today from key fields for our tomorrow. This paper thus proposes to demonstrate how in a time that can be regarded as one of the most serious crises in its history, Colombia could, in an atmosphere free from fratricidal conflicts, exploit its space matter capabilities. We do not limit our focus to the scientific field, but also consider the social, economic and cultural aspects. The results of this research delineate how Colombia could start a new optimistic phas e of its development, joining the international space programs within the framework of agreements among the regional governments in Latin America.

  4. Creating social spaces to tackle AIDS-related stigma

    DEFF Research Database (Denmark)

    Campbell, C.; Skovdal, Morten; Gibbs, A.

    2011-01-01

    An expanding body of literature explores the role of African church groups in facilitating or hindering the support of people living with AIDS and challenging or contributing to HIV/AIDS-related stigma. Treating church groups as social spaces in which HIV/AIDS-related stigma may potentially...... be challenged, we systematically review this literature, identifying five themes that highlight the complex and contradictory role of the church as a potential agent of health-enhancing social change. In many ways the church perpetuates HIV/AIDS-related stigma through (i) moralistic attitudes and (ii) its......) providing social spaces for challenging stigmatising ideas and practices. We conclude that church groups, including church leadership, can play a key role in facilitating or hindering the creation of supportive social spaces to challenge stigma. Much work remains to be done in developing deeper...

  5. Colombia: reasons to create a national space agency

    Science.gov (United States)

    Arenales-Vergara, Oscar A.

    2004-01-01

    All modern nations are concerned with their independence, whether political, economic, or intellectual. That is why we support countries which are in the process of development becoming actively involved in the international space scene. Indeed, having limitations in industrial and technological exchange, we feel excluded today from key fields which hold promise for our future. The present moment is one of serious crises in Colombia's history. This paper thus proposes to demonstrate how the nation could, in an atmosphere free from fratricidal conflicts, exploit its space capabilities. We do not limit our focus to the scientific field, but also consider the social, economic and cultural aspects. The results of this research delineate how Colombia could start a new optimistic phase of its development, joining the international space programs within the framework of agreements among the regional governments in Latin America.

  6. Innovating Customer Value : A study in creating uncontested market space

    OpenAIRE

    Mosseby, Per; Made, Björn Petter

    2005-01-01

    A number of new companies are rapidly becoming successful in established markets, or are creating new markets for themselves where there is little or no competition. Their services and products seem to knockout their competition by offering significantly higher value compared to older products. The main purpose of this thesis is to choose a few fast-growing consumer focused companies, and study their business models’ comparative customer value, value creation and viral marketing components in...

  7. Cultural Agents Creating Texts: A Collaborative Space Adventure

    Science.gov (United States)

    Daniels, Karen

    2014-01-01

    This paper discusses the ways in which young children collaboratively use narrative play and the available space and materials around them in order to exert cultural agency. The collaborative creation of texts is asserted as central to this expression of agency. By presenting an illustrative vignette of a group of 5-year-old boys as they engage in…

  8. Safe Zones: Creating LGBT Safe Space Ally Programs

    Science.gov (United States)

    Poynter, Kerry John; Tubbs, Nancy Jean

    2008-01-01

    This article discusses model LGBT Safe Space Ally programs. These programs, often called "Safe Zones," include self selected students, faculty, and employees who publicly show support by displaying stickers, signs, and other identifiable items. Issues covered in the article include history, development, training, membership, assessment, and…

  9. PRECISION COSMOGRAPHY WITH STACKED VOIDS

    Energy Technology Data Exchange (ETDEWEB)

    Lavaux, Guilhem [Department of Physics, University of Illinois at Urbana-Champaign, 1002 West Green Street, Urbana, IL 61801 (United States); Wandelt, Benjamin D. [UPMC Univ Paris 06, UMR 7095, Institut d' Astrophysique de Paris, 98 bis, boulevard Arago, 75014 Paris (France)

    2012-08-01

    We present a purely geometrical method for probing the expansion history of the universe from the observation of the shape of stacked voids in spectroscopic redshift surveys. Our method is an Alcock-Paczynski (AP) test based on the average sphericity of voids posited on the local isotropy of the universe. It works by comparing the temporal extent of cosmic voids along the line of sight with their angular, spatial extent. We describe the algorithm that we use to detect and stack voids in redshift shells on the light cone and test it on mock light cones produced from N-body simulations. We establish a robust statistical model for estimating the average stretching of voids in redshift space and quantify the contamination by peculiar velocities. Finally, assuming that the void statistics that we derive from N-body simulations is preserved when considering galaxy surveys, we assess the capability of this approach to constrain dark energy parameters. We report this assessment in terms of the figure of merit (FoM) of the dark energy task force and in particular of the proposed Euclid mission which is particularly suited for this technique since it is a spectroscopic survey. The FoM due to stacked voids from the Euclid wide survey may double that of all other dark energy probes derived from Euclid data alone (combined with Planck priors). In particular, voids seem to outperform baryon acoustic oscillations by an order of magnitude. This result is consistent with simple estimates based on mode counting. The AP test based on stacked voids may be a significant addition to the portfolio of major dark energy probes and its potentialities must be studied in detail.

  10. Effect of void cluster on ductile failure evolution

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2016-01-01

    The behavior of a non-uniform void distribution in a ductile material is investigated by using a cell model analysis to study a material with a periodic pattern of void clusters. The special clusters considered consist of a number of uniformly spaced voids located along a plane perpendicular...... to the maximum principal tensile stress. A plane strain approximation is used, where the voids are parallel cylindrical holes. Clusters with different numbers of voids are compared with the growth of a single void, such that the total initial volume of the voids, and thus also the void volume fractions...... understanding, different transverse stresses on the unit cell are considered to see the influence of different levels of stress triaxiality. Also considered are different initial ratios of the void spacing to the void radius inside the clusters. And results are shown for different levels of strain hardening...

  11. “Strange Ceremonies”: Creating Imaginative Spaces in Bizarre Magick

    OpenAIRE

    Taylor, Nik

    2016-01-01

    The Great God Pan (Raven, 1974) is a performance magic piece aimed at transporting the imagination of an audience out of the magician’s study (where the piece is set) and into fictional realms of fantasy and horror. This type of work is known as Bizarre Magick and is an underground form of performance magic. Many of the pieces in this genre borrow from popular horror fictions and seek to locate Fantastika in everyday physical locations through the creation of a charged sense of space where i...

  12. Creating new opportunities for communicating about space science

    Science.gov (United States)

    Treise, Debbie

    1996-01-01

    With the political and economic atmosphere changing so drastically, NASA has found it necessary to change its mission from one of exploration to that of accountability and application. These changes have made it difficult for NASA to access how its roles and constituency groups have changed in response. Specifically, at the MSFC Space Sciences Lab, management must now decide the most appropriate communication objectives, strategies and target market to direct messages reflecting these changes. Complicating the issue is that MSFC, must walk a fine line between looking as though it is spending too much money and 'marketing' themselves, which it is strictly prohibited from doing, and imparting the information in an exciting enough form to be picked up by the media.

  13. One-pot formation of SnO2 hollow nanospheres and α-Fe2O3@SnO2 nanorattles with large void space and their lithium storage properties

    KAUST Repository

    Chen, Jun Song

    2009-01-01

    In this work, uniform SnO2 hollow nanospheres with large void space have been synthesized by a modified facile method. The void space can be easily controlled by varying the reaction time. The formation of interior void space is based on an inside-out Ostwald ripening mechanism. More importantly, this facile one-pot process can be extended to fabricate rattle-type hollow structures using α-Fe2O3@SnO2 as an example. Furthermore, the electrochemical lithium storage properties have been investigated. It is found that α-Fe2O3@SnO 2 nanorattles manifest a much lower initial irreversible loss and higher reversible capacity compared to SnO2 hollow spheres. This interesting finding supports a general hypothesis that a synergistic effect between functional core and shell materials can lead to improved lithium storage capabilities. © The Royal Society of Chemistry 2009.

  14. Computerized voiding diary.

    Science.gov (United States)

    Rabin, J M; McNett, J; Badlani, G H

    1993-01-01

    An electronic, computerized voiding diary, "Compu-Void" (patent pending) was developed in order to simplify, augment, and automate patients' recording of bladder symptomatology. A voiding diary as a tool has the potential to provide essential information for a more complete diagnostic and therefore therapeutic picture for each patient. Two major problems with the standard written voiding diary have been a lack of patient compliance and the limited amount of information it garners. Twenty-five women with various types of voiding dysfunctions were compared to twenty-five age and parity-matched control women in order to determine patient preferences of the Compu-Void when compared to the standard written voiding diary, compliance with each method, and amount and quality of information obtained with each method. Over 90% of subjects and over 70% of control group patients preferred the Compu-Void over the written diary (P Compu-Void exceeded that obtained with the written method.

  15. Rational design of MnO/carbon nanopeapods with internal void space for high-rate and long-life li-ion batteries.

    Science.gov (United States)

    Jiang, Hao; Hu, Yanjie; Guo, Shaojun; Yan, Chaoyi; Lee, Pooi See; Li, Chunzhong

    2014-06-24

    Searching the long-life MnO-based materials for lithium ion batteries (LIBs) is still a great challenge because of the issue related to the volumetric expansion of MnO nanoparticles (NPs) or nanowires (NWs) during lithiation. Herein, we demonstrate an unexpected result that a peapod-like MnO/C heterostructure with internal void space can be facilely prepared by annealing the MnO precursor (MnO-P) NW/polydopamine core/shell nanostructure in an inert gas, which is very different from the preparation of typical MnO/C core/shell NWs through annealing MnO NW/C precursor nanostructure. Such peapod-like MnO/C heterostructure with internal void space is highly particular for high-performance LIBs, which can address all the issues related to MnO dissolution, conversion, aggregation and volumetric expansion during the Li(+) insertion/extraction. They are highly stable anode material for LIBs with a very high reversible capacity (as high as 1119 mAh g(-1) at even 500 mA g(-1)) and fast charge and discharge capability (463 mAh g(-1) at 5000 mA g(-1)), which is much better than MnO NWs (38 mAh g(-1) at 5000 mA g(-1)) and MnO/C core/shell NWs (289 mAh g(-1) at 5000 mA g(-1)). Such nanopeapods also show excellent rate capability (charged to 91.6% in 10.6 min using the constant current mode). Most importantly, we found that MnO/C nanopeapods show no capacity fading even after 1000 cycles at a high current density of 2000 mA g(-1), and no morphology change. The present MnO/C nanopeapods are the most efficient MnO-based anode materials ever reported for LIBs.

  16. Air void structure and frost resistance

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange

    2014-01-01

    is proportional to the product of total air content and specific surface. In all 4 cases, the conclusion is concurrent that the parameter of total surface area of air voids performs equally well or better than the spacing factor when linking air void characteristics to frost resistance (salt frost scaling...... will take place in the air void, being feed from the capillary, but without pressure build-up in the capillary. If the capillary is not connected to an air void, ice formation will take place in the capillary pore, where it can generate substantial pressure. Like this, frost resistance depends......This article compiles results from 4 independent laboratory studies. In each study, the same type of concrete is tested at least 10 times, the air void structure being the only variable. For each concrete mix both air void analysis of the hardened concrete and a salt frost scaling test...

  17. The Development of Voiding

    DEFF Research Database (Denmark)

    Olsen, Lars Henning

    2011-01-01

    The thesis addresses some new aspeccts in the development of voiding function from midgestation into early childhood.......The thesis addresses some new aspeccts in the development of voiding function from midgestation into early childhood....

  18. The Void Galaxy Survey

    CERN Document Server

    van de Weygaert, R; Platen, E; Beygu, B; van Gorkom, J H; van der Hulst, J M; Aragon-Calvo, M A; Peebles, P J E; Jarrett, T; Rhee, G; Kovac, K; Yip, C -W

    2011-01-01

    The Void Galaxy Survey (VGS) is a multi-wavelength program to study $\\sim$60 void galaxies. Each has been selected from the deepest interior regions of identified voids in the SDSS redshift survey on the basis of a unique geometric technique, with no a prior selection of intrinsic properties of the void galaxies. The project intends to study in detail the gas content, star formation history and stellar content, as well as kinematics and dynamics of void galaxies and their companions in a broad sample of void environments. It involves the HI imaging of the gas distribution in each of the VGS galaxies. Amongst its most tantalizing findings is the possible evidence for cold gas accretion in some of the most interesting objects, amongst which are a polar ring galaxy and a filamentary configuration of void galaxies. Here we shortly describe the scope of the VGS and the results of the full analysis of the pilot sample of 15 void galaxies.

  19. Supplemental topics on voids

    Energy Technology Data Exchange (ETDEWEB)

    Rood, H.J.

    1988-09-01

    Several topics concerning voids are presented, supplementing the report of Rood (1988). The discovery of the Coma supercluster and void and the recognition of the cosmological significance of superclusters and voids are reviewed. Galaxy redshift surveys and redshift surveys for the Abell clusters and very distant objects are discussed. Solar system and extragalactic dynamics are examined. Also, topics for future observational research on voids are recommended. 50 references.

  20. Atomistic modeling of shock-induced void collapse in copper

    Energy Technology Data Exchange (ETDEWEB)

    Davila, L P; Erhart, P; Bringa, E M; Meyers, M A; Lubarda, V A; Schneider, M S; Becker, R; Kumar, M

    2005-03-09

    Nonequilibrium molecular dynamics (MD) simulations show that shock-induced void collapse in copper occurs by emission of shear loops. These loops carry away the vacancies which comprise the void. The growth of the loops continues even after they collide and form sessile junctions, creating a hardened region around the collapsing void. The scenario seen in our simulations differs from current models that assume that prismatic loop emission is responsible for void collapse. We propose a new dislocation-based model that gives excellent agreement with the stress threshold found in the MD simulations for void collapse as a function of void radius.

  1. Precision cosmography with stacked voids

    CERN Document Server

    Lavaux, Guilhem

    2011-01-01

    We present a purely geometrical method for probing the expansion history of the Universe from the observation of the shape of stacked voids in spectroscopic re dshift surveys. Our method is an Alcock-Pasczinsky test based on the average sphericity of voids posited on the local isotropy of the Universe. It works by comparing the temporal extent of cosmic voids along the line of sight with their angular, spatial extent. We describe the algorithm that we use to detect and stack voids in redshift shells on the light cone and test it on mock light cones produced from N-body simulations. We establish a robust statistical model for estimating the average stretching of voids in redshift space and quantify the contamination by peculiar velocities. Finally, we assess the capability of this approach to constrain dark energy parameters in terms of the figure of merit (FoM) of the dark energy task force and in particular of the proposed Euclid mission which is particularly suited for this technique since it is a spectrosc...

  2. Repurposing With Purpose: Creating a Collaborative Learning Space to Support Institutional Interprofessional Initiatives.

    Science.gov (United States)

    Young, Lauren M; Machado, Connie K; Clark, Susan B

    2015-01-01

    When the University of Mississippi Medical Center embraced a didactic shift to patient-centered, interprofessional education of its medical, dental, nursing, pharmacy, and allied health students, the Rowland Medical Library repurposed space to support the cause and created a collaborative learning space designated for campus-wide utility.

  3. Three-Dimensional Computed Tomography as a Method for Finding Die Attach Voids in Diodes

    Science.gov (United States)

    Brahm, E. N.; Rolin, T. D.

    2010-01-01

    NASA analyzes electrical, electronic, and electromechanical (EEE) parts used in space vehicles to understand failure modes of these components. The diode is an EEE part critical to NASA missions that can fail due to excessive voiding in the die attach. Metallography, one established method for studying the die attach, is a time-intensive, destructive, and equivocal process whereby mechanical grinding of the diodes is performed to reveal voiding in the die attach. Problems such as die attach pull-out tend to complicate results and can lead to erroneous conclusions. The objective of this study is to determine if three-dimensional computed tomography (3DCT), a nondestructive technique, is a viable alternative to metallography for detecting die attach voiding. The die attach voiding in two- dimensional planes created from 3DCT scans was compared to several physical cross sections of the same diode to determine if the 3DCT scan accurately recreates die attach volumetric variability

  4. Non-conjugate potential-stepping phenothiazine and phenoxazine based polymer hole-transport material for dye-sensitized solar cells & increasing void space in porous titanium dioxide: To study diffusion properties of a cobalt mediator

    Science.gov (United States)

    Persson, Kristoffer

    -stacking interactions at the center of the helix, which allows electrons to tunnel through the DNA strand. A potential-stepping block co-polymer incorporating phenothiazine (PTZ) and phenoxazine (POZ) groups attached to the polymer backbone can π-stack like the base pairs in DNA. By creating a two-block co-polymer, with one composed of PTZ monomers and the other of POZ monomers, charge separation can be achieved by trapping the hole on the POZ groups due to their more negative oxidation potentials. This potential-stepping polymer charge separator is the focus of the first part of this thesis. The second section of this thesis is centered on diffusion issues in DSSCs where the I-/ I3- mediator is replaced with tris((2,2'-bipyridyl-4,4'-di-tert-butyl)cobalt(III) perchlorate, CoDTB+3 (ClO4-) 3 (DTB = 4,4‧-di-tert-butyl-2,2‧-bipyridine). The cobalt mediator has many advantages: it is non-corrosive, non-volatile, and it is able to be tuned to optimize the electron transfer process to the dye by simple structural modifications of the ligand. However, cobalt mediators have small diffusion coefficients on the order of 1x10-7 cm2 s-1 or less in TiO2 mesoporous thin films. It has been hypothesized that changing the structure of the TiO2 layer or increasing the void space in the films in the correct manner may dramatically increase the effective rate of diffusion. The introduction of appropriate void space will hypothetically create channels and allow faster diffusion of the mediator. The second half of this thesis explores the effects of introducing void space into TiO2 thin films using various nanoparticles.

  5. "Amazing Space": Creating Educational Resources from Current Scientific Research Results from the Hubble Space Telescope.

    Science.gov (United States)

    Christian, C. A.; Eisenhamer, B.; Eisenhamer, Jonathan; Teays, Terry

    2001-01-01

    Introduces the Amazing Space program which is designed to enhance student mathematics, science, and technology skills using recent data and results from the National Aeronautics and Space Administration's (NASA) Hubble Space Telescope mission. Explains the process of designing multi-media resources in a five-week summer workshop that partners…

  6. Green synthesis of Pt-doped TiO2 nanocrystals with exposed (001) facets and mesoscopic void space for photo-splitting of water under solar irradiation.

    Science.gov (United States)

    Banerjee, Biplab; Amoli, Vipin; Maurya, Abhayankar; Sinha, Anil Kumar; Bhaumik, Asim

    2015-06-21

    We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and N2 sorption studies. These Pt/TiO2 nanocrystals with (001) exposed facets are employed as efficient and benign catalysts for hydrogen production from pure water and methanol-water systems under one AM 1.5G sunlight illumination. The effect of platinum loading and methanol-water ratio on the photocatalytic activity of the faceted TiO2 nanocrystals are investigated and it is found that hydrogen evolution rates have been enhanced significantly upon Pt loading. Under optimized reaction conditions the highest photocatalytic activity of 11.2 mmol h(-1) g(-1) has been achieved over ca. 1.0 wt% Pt loaded Pt/TiO2 nanocrystals with (001) exposed facets, which is one of the highest hydrogen evolution rates over the noble metal/TiO2 system reported to date in the literature.

  7. Underground void filling by cemented mill tailings

    Institute of Scientific and Technical Information of China (English)

    Choudhary Bhanwar Singh; Kumar Santosh

    2013-01-01

    Underground mining always create voids. These voids can cause subsidence of surface. So it is always a demand to fill the void in such a manner that the effect of underground mining can be minimized. Void filling using mill tailings especially in metal mining is one of the best techniques. The tailings produced in milling process have traditionally been disposed in tailing ponds creating a waste disposal and environ-mental problems in terms of land degradation, air and water pollution, etc. This disposal practice is more acute in the metal milling industry where the fine grinding, required for value liberation, results in the production of very fine tailings in large percentage. This paper includes discussions on the effectiveness of different paste mixes with varying cement contents in paste backfilling operations. The results revealed that material composition and use of super plasticizer strongly influenced the strength of cemented backfill.

  8. Space Junk Norms: US Advantages in Creating a Debris Reducing Outer Space Norm

    Science.gov (United States)

    2011-05-01

    represented by the debate over space weaponization. Stephen Krasner defines norms as “standards of behavior defined in terms of rights and...designer of the 20 Stephen Clark, “Air Force Spaceplane is an Odd Bird with a Twisted Path...the Sea. New., rev. ed. Manchester: University Press, 1988. Clark, Stephen . “Air Force Spaceplane is an Odd Bird with a Twisted Path,” Space.com, 2

  9. Science Students Creating Hybrid Spaces When Engaging in an Expo Investigation Project

    Science.gov (United States)

    Ramnarain, Umesh; de Beer, Josef

    2013-01-01

    In this paper, we report on the experiences of three 9th-grade South African students (13-14 years) in doing open science investigation projects for a science expo. A particular focus of this study was the manner in which these students merge the world of school science with their social world to create a hybrid space by appropriating knowledge…

  10. Welcoming and Restoring, Dwelling and Sending: Creating a Space for Hospitality in Faculty Development

    Science.gov (United States)

    Larson, Marion H.

    2009-01-01

    Parker Palmer's (1983) often-quoted definition of teaching--"To teach is to create a space in which obedience to truth is practiced"--can be applied productively to work in faculty development. Exploring this notion is enhanced by the theological literature in hospitality, which can be viewed through Amy Oden's (2001) discussion of four movements…

  11. Finding a Third Space in Teacher Education: Creating an Urban Teacher Residency

    Science.gov (United States)

    Klein, Emily J.; Taylor, Monica; Onore, Cynthia; Strom, Kathryn; Abrams, Linda

    2013-01-01

    This paper describes an urban teacher residency program, the Newark Montclair Urban Teacher Residency, a collaborative endeavor between the Newark, New Jersey Public Schools and Montclair State University, built on a decades-long partnership. The authors see the conceptual work of developing this program as creating a "third space" in…

  12. Cultivating Research Pedagogies with Adolescents: Created Spaces, Engaged Participation, and Embodied Inquiry

    Science.gov (United States)

    Wissman, Kelly K.; Staples, Jeanine M.; Vasudevan, Lalitha; Nichols, Rachel E.

    2015-01-01

    This paper conceptualizes an approach to adolescent literacies research we call "research pedagogies." This approach recognizes the pedagogical features of the research process and includes three dimensions: created spaces, engaged participation, and embodied inquiry. By drawing upon and sometimes recasting foundational anthropological…

  13. Science Students Creating Hybrid Spaces When Engaging in an Expo Investigation Project

    Science.gov (United States)

    Ramnarain, Umesh; de Beer, Josef

    2013-01-01

    In this paper, we report on the experiences of three 9th-grade South African students (13-14 years) in doing open science investigation projects for a science expo. A particular focus of this study was the manner in which these students merge the world of school science with their social world to create a hybrid space by appropriating knowledge…

  14. Creating the Thermal Environment for Safely Testing the James Webb Space Telescope at the Johnson Space Center's Chamber A

    Science.gov (United States)

    Homan, Jonathan L.; Lauterbach, John; Garcia, Sam

    2016-01-01

    Chamber A is the largest thermal vacuum chamber at the Johnson Space Center and is one of the largest space environment chambers in the world. The chamber is 19.8 m (65 ft) in diameter and 36.6 m (120 ft) tall and is equipped with cryogenic liquid nitrogen panels (shrouds) and gaseous helium shrouds to create a simulated space environment. The chamber was originally built to support testing of the Apollo Service and Command Module for lunar missions, but underwent major modifications to be able to test the James Webb Space Telescope in a simulated deep space environment. To date seven tests have been performed in preparation of testing the flight optics for the James Webb Space Telescope (JWST). Each test has had a uniquie thermal profile and set of thermal requirements for cooling down and warming up, controlling contamination, and releasing condensed air. These range from temperatures from 335K to 15K, with tight uniformity and controllability for maintining thermal stability and pressure control. One unique requirement for two test was structurally proof loading hardware by creating thermal gradients at specific temperatures. This paper will discuss the thermal requirements and goals of the tests, the original requirements of the chamber thermal systems for planned operation, and how the new requirements were met by the team using the hardware, system flexiblilty, and engineering creativity. It will also discuss the mistakes and successes to meet the unique goals, especially when meeting the thermal proof load.

  15. Voiding dysfunction - A review

    Directory of Open Access Journals (Sweden)

    Sripathi V

    2005-01-01

    Full Text Available In a child who is toilet trained the sudden onset of daytime wetting with frequency or urgency is alarming to the parents. Initially this subject was subdivided into a number of descriptive clinical conditions which led to a lot of confusion in recognition and management. Subsequently, the term elimination dysfunction was coined by Stephen Koff to emphasise the association between recurrent urinary infection, wetting, constipation and bladder overactivity. From a urodynamic point of view, in voiding dysfunction, there is either detrusor overactivity during bladder filling or dyssynergic action between the detrusor and the external sphincter during voiding. Identifying a given condition as a ′filling phase dysfunction′ or ′voiding phase dysfunction′ helps to provide appropriate therapy. Objective clinical criteria should be used to define voiding dysfunction. These include bladder wall thickening, large capacity bladder and infrequent voiding, bladder trabeculation and spinning top deformity of the urethra and a clinically demonstrated Vincent′s curtsy. The recognition and treatment of constipation is central to the adequate treatment of voiding dysfunction. Transcutaneous electric nerve stimuation for the treatment of detrusor overactivity, biofeedback with uroflow EMG to correct dyssynergic voiding, and behavioral therapy all serve to correct voiding dysfunction in its early stages. In established neurogenic bladder disease the use of Botulinum Toxin A injections into the detrusor or the external sphincter may help in restoring continence especially in those refractory to drug therapy. However in those children in whom the upper tracts are threatened, augmentation of the bladder may still be needed.

  16. Green synthesis of Pt-doped TiO2 nanocrystals with exposed (001) facets and mesoscopic void space for photo-splitting of water under solar irradiation

    Science.gov (United States)

    Banerjee, Biplab; Amoli, Vipin; Maurya, Abhayankar; Sinha, Anil Kumar; Bhaumik, Asim

    2015-06-01

    We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and N2 sorption studies. These Pt/TiO2 nanocrystals with (001) exposed facets are employed as efficient and benign catalysts for hydrogen production from pure water and methanol-water systems under one AM 1.5G sunlight illumination. The effect of platinum loading and methanol-water ratio on the photocatalytic activity of the faceted TiO2 nanocrystals are investigated and it is found that hydrogen evolution rates have been enhanced significantly upon Pt loading. Under optimized reaction conditions the highest photocatalytic activity of 11.2 mmol h-1 g-1 has been achieved over ca. 1.0 wt% Pt loaded Pt/TiO2 nanocrystals with (001) exposed facets, which is one of the highest hydrogen evolution rates over the noble metal/TiO2 system reported to date in the literature.We report a non-trivial facile chemical approach using ionic liquid ([bmim][Cl]) as a porogen for the synthesis of (001) faceted TiO2 nanocrystals having mesoscopic void space. This faceted TiO2 nanomaterial has been doped with Pt nanoclusters through chemical impregnation. The resulting Pt-doped TiO2 nanomaterials are thoroughly characterized by powder X-ray diffraction (PXRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), ultra high resolution transmission electron microscopy (UHR-TEM), energy dispersive X-ray spectrometry (EDX), UV-vis diffuse reflection spectroscopy (DRS) and

  17. Creating and Exploring Huge Parameter Spaces: Interactive Evolution as a Tool for Sound Generation

    DEFF Research Database (Denmark)

    Dahlstedt, Palle

    2001-01-01

    of huge synthesis parameter spaces, and presents a possibility for the sound artist to create new sound engines customized for this kind of creation and exploration – sound engines too complex to control in any other way. Different sound engines are presented, together with a discussion of compositional......In this paper, a program is presented that applies interactive evolution to sound generation, i.e., preferred individuals are repeatedly selected from a population of genetically bred sound objects, created with various synthesis and pattern generation algorithms. This simplifies aural exploration...

  18. Dark matter in voids

    Science.gov (United States)

    Fong, Richard; Doroshkevich, Andrei G.; Turchaninov, Victor I.

    1995-07-01

    The theory of the formation of large-scale structure in the universe through the action of gravitational instability imply the existence of substantial amounts of baryonic dark matter, of the order of 50% of the total baryon content in the universe, in the ``voids'' or under-dense regions seen in the large-scale distribution of galaxies. We discuss also the large-scale structure of dark matter expected in voids and the present and future possibilities for the observation of this baryonic dark matter in ``voids.''

  19. Dark matter in voids

    Energy Technology Data Exchange (ETDEWEB)

    Fong, R. [Department of Physics, University of Durham, Durham, DH1 3LE (United Kingdom); Doroshkevich, A.G. [Keldysh Institute of Applied Mathematics, 125047 Moscow (Russian Federation)]|[Teoretical Astrophysics Centrum, Blegsdamsvej 17, Copenhagen DK 2100 (Denmark); Turchaninov, V.I. [Keldysh Institute of Applied Mathematics, 125047 Moscow (Russian Federation)

    1995-07-01

    The theory of the formation of large-scale structure in the universe through the action of gravitational instability imply the existence of substantial amounts of baryonic dark matter, of the order of 50% of the total baryon content in the universe, in the ``voids`` or under-dense regions seen in the large-scale distribution of galaxies. We discuss also the large-scale structure of dark matter expected in voids and the present and future possibilities for the observation of this baryonic dark matter in ``voids.`` {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  20. Tailored Synthesis of Porous TiO₂ Nanocubes and Nanoparallelepipeds with Exposed {111} Facets and Mesoscopic Void Space: A Superior Candidate for Efficient Dye-Sensitized Solar Cells.

    Science.gov (United States)

    Amoli, Vipin; Bhat, Shekha; Maurya, Abhayankar; Banerjee, Biplab; Bhaumik, Asim; Sinha, Anil Kumar

    2015-12-02

    Anatase TiO2 nanocubes and nanoparallelepipeds, with highly reactive {111} facets exposed, were developed for the first time through a modified one pot hydrothermal method, through the hydrolysis of tetrabutyltitanate in the presence of oleylamine as the morphology-controlling capping-agent and using ammonia/hydrofluoric acid for stabilizing the {111} faceted surfaces. These nanocubes/nanoparallelepipeds were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), high resolution transmission electron microscopy (HRTEM) and high angle annular dark-field scanning TEM (HAADF-STEM). Accordingly, a possible growth mechanism for the nanostructures is elucidated. The morphology, surface area and the pore size distribution of the TiO2 nanostructures can be tuned simply by altering the HF and ammonia dosage in the precursor solution. More importantly, optimization of the reaction system leads to the assembly of highly crystalline, high surface area, {111} faceted anatase TiO2 nanocubes/nanoparallelepipeds to form uniform mesoscopic void space. We report the development of a novel double layered photoanode for dye sensitized solar cells (DSSCs) made of highly crystalline, self-assembled faceted TiO2 nanocrystals as upper layer and commercial titania nanoparticles paste as under layer. The bilayered DSSC made from TiO2 nanostructures with exposed {111} facets as upper layer shows a much higher power conversion efficiency (9.60%), than DSSCs fabricated with commercial (P25) titania powder (4.67%) or with anatase TiO2 nanostructures having exposed {101} facets (7.59%) as the upper layer. The improved performance in bilayered DSSC made from TiO2 nanostructures with exposed {111} facets as the upper layer is attributed to high dye adsorption and fast electron transport dynamics owing to the unique structural features of the {111} facets in TiO2. Electrochemical impedance spectroscopy (EIS) measurements conducted on the cells supported these conclusions

  1. STRESS CONCENTRATION DUE TO A SPHERICAL VOID UNDER HERTZIAN CONTACT

    Directory of Open Access Journals (Sweden)

    Stelian ALACI,

    2010-06-01

    Full Text Available The present paper presents the method of estimating the stress concentrator effect of a spherical void from an elastic half-space. An essential part consists in estimation of FEM error by finding the contact pressure from half-plane using an analytical method. Next, the stress concentrator effect of the same void, except for placed into elastic space, is found.

  2. On de-Sitter Geometry in Cosmic Void Statistics

    CERN Document Server

    Gibbons, Gary W; Yoshida, Naoki; Chon, Sunmyon

    2013-01-01

    Starting from the geometrical concept of a 4-dimensional de-Sitter configuration of spheres in Euclidean 3-space and modelling voids in the Universe as spheres, we show that a uniform distribution over this configuration space implies a power-law for the void number density which is consistent with results from the excursion set formalism and from data, for an intermediate range of void volumes. We also discuss the effect of restricting the survey geometry on the void statistics. This work is a new application of de-Sitter geometry to cosmology and also provides a new geometrical perspective on self-similarity in cosmology.

  3. Interaction Design Beyond the Product : Creating Technology-Enhanced Activity Spaces

    DEFF Research Database (Denmark)

    Kaptelinin, Victor; Bannon, Liam J.

    2012-01-01

    The field of interaction design to date has been predominantly concerned with designing products, that is, devices, systems, and more recently services. A growing body of theoretical and empirical analyses suggests that the scope of interaction design needs to be expanded: An explicit concern...... of the field should include not only helping designers create better products but also helping people themselves create better environments for their work, learning, and leisure activities. In this article we argue that expanding the scope of interaction design beyond products requires a revision of some...... between intrinsic and extrinsic technology-enabled practice transformation, and foreground the need for interaction design research and practice to more directly deal with analysis and construction of technology-enhanced activity spaces. The implications of these notions for the research agenda...

  4. How space-number associations may be created in preliterate children: six distinct mechanisms

    Directory of Open Access Journals (Sweden)

    Hans-Christoph eNuerk

    2015-03-01

    Full Text Available The directionality of space-number association (SNA is shaped by cultural experiences. It usually follows the culturally dominant reading direction. Smaller numbers are generally associated with the starting side for reading (left side in Western cultures, while larger numbers are associated with the right endpoint side. However, SNAs consistent with cultural reading directions are present before children can actually read and write. Therefore, these SNAs cannot only be shaped by the direction of children’s own reading/writing behavior. We propose six distinct processes - one biological and five cultural/educational - underlying directional space-number associations before formal reading acquisition: (i Brain lateralization (ii Monitoring adult reading behavior, (iii Pretend reading and writing, and rudimentary reading and writing skills, (iv Dominant attentional directional preferences in a society, not directly related to reading direction, (v Direct spatial-numerical learning, (vi Other spatial-directional processes independent of reading direction. In this mini-review, we will differentiate between these processes, elaborate when in development they might emerge, discuss how they may create the space-number associations observed in preliterate children and propose how they can be studied in the future.

  5. Creating a public space and dialogue on sexuality and rights: a case study from Bangladesh.

    Science.gov (United States)

    Rashid, Sabina Faiz; Standing, Hilary; Mohiuddin, Mahrukh; Ahmed, Farah Mahjabeen

    2011-06-16

    This article describes and analyses a research based engagement by a university school of public health in Bangladesh aimed at raising public debate on sexuality and rights and making issues such as discrimination more visible to policy makers and other key stakeholders in a challenging context. The impetus for this work came from participation in an international research programme with a particular interest in bridging international and local understandings of sexual and reproductive rights. The research team worked to create a platform to broaden discussions on sexuality and rights by building on a number of research activities on rural and urban men's and women's sexual health concerns, and on changing concepts of sexuality and understandings of sexual rights among specific population groups in Dhaka city, including sexual minorities. Linked to this on-going process of improving the evidence base, there has been a series of learning and capacity building activities over the last four years consisting of training workshops, meetings, conferences and dialogues. These brought together different configurations of stakeholders - members of sexual minorities, academics, service providers, advocacy organisations, media and policy makers. This process contributed to developing more effective advocacy strategies through challenging representations of sexuality and rights in the public domain. Gradually, these efforts brought visibility to hidden or stigmatised sexuality and rights issues through interim outcomes that have created important steps towards changing attitudes and policies. These included creating safe spaces for sexual minorities to meet and strategise, development of learning materials for university students and engagement with legal rights groups on sexual rights. Through this process, it was found to be possible to create a public space and dialogue on sexuality and rights in a conservative and challenging environment like Bangladesh by bringing

  6. Void shape effects and voids starting from cracked inclusion

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2011-01-01

    Numerical, axisymmetric cell model analyses are used to study the growth of voids in ductile metals, until the mechanism of coalescence with neighbouring voids sets in. A special feature of the present analyses is that extremely small values of the initial void volume fraction are considered, dow...

  7. The Use of Epistemic Distancing to Create a Safe Space to Sensemake in Introductory Physics Tutorials

    CERN Document Server

    Conlin, Luke D

    2015-01-01

    In active engagement physics classrooms, students get opportunities to make sense of physics together through discussion. They do not always take up these opportunities, in part because of the risk of sharing their ideas and having them rejected by their classmates or the instructors. In this case study, I analyze videotaped discourse of a tutorial group's early discussions to investigate how students manage these risks in creating a safe space to sensemake. I find that the students and instructors alike rely on a common discursive resource - epistemic distancing - to share their ideas while protecting themselves affectively if others disagree. Epistemic distancing includes hedging, joking, deferring, and other discourse moves used to soften one's stance in conversation. I use video analysis to illustrate the effects of these moves on tutorial groups' sensemaking discussions, and discuss implications for instructors wishing to encourage sensemaking discussions in their physics classrooms.

  8. From Sanctuaries to Prefigurative Social Change: Creating Health-Enabling Spaces in East London Community Gardens

    Directory of Open Access Journals (Sweden)

    Madeleine A. Guerlain

    2016-05-01

    for effective community mobilization. AIDS Care, 22(Suppl. 2, 1569-1579; and a discussion of how creating these spaces is an act of prefigurative social change. Our findings suggest that in East London, participation in community gardens is not based on a common political intention or self-conscious motive to prefigure a new society, but instead on the shared practice of gardening. This results in unintended benefits that often address participants’ personal adversities in ways that contribute to the material, relational and symbolic deprivation of their daily lives – opening up new possibilities for being, seeing and doing. In this sense, community gardens in East London offer an alternative to traditional notions of prefigurative social action that are predicated on strategic intention. We argue for an understanding of prefiguration that better accounts for what participants themselves would like to achieve in their own lives, rather than in relation to externally imposed notions of what counts as political change.

  9. Creating a Discovery Platform for Confined-Space Chemistry and Materials: Metal-Organic Frameworks.

    Energy Technology Data Exchange (ETDEWEB)

    Allendorf, Mark D.; Greathouse, Jeffery A.; Simmons, Blake

    2008-09-01

    Metal organic frameworks (MOF) are a recently discovered class of nanoporous, defect-free crystalline materials that enable rational design and exploration of porous materials at the molecular level. MOFs have tunable monolithic pore sizes and cavity environments due to their crystalline nature, yielding properties exceeding those of most other porous materials. These include: the lowest known density (91% free space); highest surface area; tunable photoluminescence; selective molecular adsorption; and methane sorption rivaling gas cylinders. These properties are achieved by coupling inorganic metal complexes such as ZnO4 with tunable organic ligands that serve as struts, allowing facile manipulation of pore size and surface area through reactant selection. MOFs thus provide a discovery platform for generating both new understanding of chemistry in confined spaces and novel sensors and devices based on their unique properties. At the outset of this project in FY06, virtually nothing was known about how to couple MOFs to substrates and the science of MOF properties and how to tune them was in its infancy. An integrated approach was needed to establish the required knowledge base for nanoscale design and develop methodologies integrate MOFs with other materials. This report summarizes the key accomplishments of this project, which include creation of a new class of radiation detection materials based on MOFs, luminescent MOFs for chemical detection, use of MOFs as templates to create nanoparticles of hydrogen storage materials, MOF coatings for stress-based chemical detection using microcantilevers, and "flexible" force fields that account for structural changes in MOFs that occur upon molecular adsorption/desorption. Eight journal articles, twenty presentations at scientific conferences, and two patent applications resulted from the work. The project created a basis for continuing development of MOFs for many Sandia applications and succeeded in securing $2.75 M in

  10. Plasticity size effects in voided crystals

    DEFF Research Database (Denmark)

    Hussein, M. I.; Borg, Ulrik; Niordson, Christian Frithiof;

    The shear and equi-biaxial straining responses of periodic voided single crystals are analysed using discrete dislocation plasticity and a continuum strain gradient crystal plasticity theory. In the discrete dislocation formulation the dislocations are all of edge character and are modelled as line...... predictions of the two formulations for all crystal types and void volume fractions considered when the material length scale in the non-local plasticity model chosen to be $0.325\\mu m$ (around ten times the slip plane spacing in the discrete dislocation models)....

  11. Neurogenic voiding dysfunction.

    Science.gov (United States)

    Georgopoulos, Petros; Apostolidis, Apostolos

    2017-05-01

    This review aims to analyze and discuss all recently published articles associated with neurogenic voiding discussion providing readers with the most updated knowledge and trigger for further research. They include the proposal of a novel classification system for the pathophysiology of neurogenic lower urinary tract dysfunction (NLUTD) which combines neurological defect in a distinct anatomic location, and data on bowel dysfunction, autonomic dysreflexia and urine biomarkers; review of patient-reported outcome measures in NLUTD; review of the criteria for the diagnosis of clinically significant urinary infections; novel research findings on the pathophysiology of NLUTD; and review of data on minimally and more invasive treatments. Despite the extended evidence base on NLUTD, there is a paucity of high-quality new research concerning voiding dysfunction as opposed to storage problems. The update aims to inform clinicians about new developments in clinical practice, as well as ignite discussion for further clinical and basic research in the aforementioned areas of NLUTD.

  12. A computerized voiding diary.

    Science.gov (United States)

    Rabin, J M; McNett, J; Badlani, G H

    1996-11-01

    To examine a group of subject and control patient's preferences and compliance with regard to the Compu-Void (CV) electronic voiding diary as compared to the written diary (WD) and to compare the two methods with respect to the type of information obtained and whether the order of use of each method influenced results in the subject group. Thirty-six women between the ages of 20 and 84 with bladder symptoms were compared to a group of 36 age-matched women. In 100% of subjects and 95% of control patients, CV entries exceeded the number made with the WD in voiding events and, in subjects, in incontinence episodes recorded (P < .005 and P < .005, respectively). Over 98% of subjects and over 80% of controls preferred the CV (P < .0005). The order of use of each method in subjects made no significant difference with regard to the volume of information obtained (P < .407), number of leakage events recorded (P < .494) or fluid intake patterns (P < .410). Patients' compliance with each method was not affected by the order of use. Our results suggest an increased volume of data and greater patient compliance in reporting bladder symptoms and events using the CV and that the order of use is not important.

  13. Void structure of concrete with superabsorbent polymers and its relation to frost resistance of concrete

    DEFF Research Database (Denmark)

    Hasholt, Marianne Tange; Jensen, Ole Mejlhede; Laustsen, Sara

    2013-01-01

    the difference between poor and satisfactory frost-resistance. Furthermore, the results indicate that voids created directly by SAP protect concrete against frost deterioration just like other air voids; if the concrete contains enough SAP voids, these alone can provide sufficient frost resistance. © 2013 RILEM....

  14. Library Spaces for 21st-Century Learners: A Planning Guide for Creating New School Library Concepts

    Science.gov (United States)

    Sullivan, Margaret

    2013-01-01

    "Library Spaces for 21st-Century Learners: A Planning Guide for Creating New School Library Concepts" focuses on planning contemporary school library spaces with user-based design strategies. The book walks school librarians and administrators through the process of gathering information from students and other stakeholders involved in…

  15. Library Spaces for 21st-Century Learners: A Planning Guide for Creating New School Library Concepts

    Science.gov (United States)

    Sullivan, Margaret

    2013-01-01

    "Library Spaces for 21st-Century Learners: A Planning Guide for Creating New School Library Concepts" focuses on planning contemporary school library spaces with user-based design strategies. The book walks school librarians and administrators through the process of gathering information from students and other stakeholders involved in…

  16. Globalisation and health inequalities: can a human rights paradigm create space for civil society action?

    Science.gov (United States)

    London, Leslie; Schneider, Helen

    2012-01-01

    While neoliberal globalisation is associated with increasing inequalities, global integration has simultaneously strengthened the dissemination of human rights discourse across the world. This paper explores the seeming contradiction that globalisation is conceived as disempowering nations states' ability to act in their population's interests, yet implementation of human rights obligations requires effective states to deliver socio-economic entitlements, such as health. Central to the actions required of the state to build a health system based on a human rights approach is the notion of accountability. Two case studies are used to explore the constraints on states meeting their human rights obligations regarding health, the first drawing on data from interviews with parliamentarians responsible for health in East and Southern Africa, and the second reflecting on the response to the HIV/AIDS epidemic in South Africa. The case studies illustrate the importance of a human rights paradigm in strengthening parliamentary oversight over the executive in ways that prioritise pro-poor protections and in increasing leverage for resources for the health sector within parliamentary processes. Further, a rights framework creates the space for civil society action to engage with the legislature to hold public officials accountable and confirms the importance of rights as enabling civil society mobilization, reinforcing community agency to advance health rights for poor communities. In this context, critical assessment of state incapacity to meet claims to health rights raises questions as to the diffusion of accountability rife under modern international aid systems. Such diffusion of accountability opens the door to 'cunning' states to deflect rights claims of their populations. We argue that human rights, as both a normative framework for legal challenges and as a means to create room for active civil society engagement provide a means to contest both the real and the

  17. Quantifying Effects of Voids in Woven Ceramic Matrix Composites

    Science.gov (United States)

    Goldsmith, Marlana B.; Sankar, Bhavani V.; Haftka, Raphael T.; Goldberg, Robert K.

    2013-01-01

    Randomness in woven ceramic matrix composite architecture has been found to cause large variability in stiffness and strength. The inherent voids are an aspect of the architecture that may cause a significant portion of the variability. A study is undertaken to investigate the effects of many voids of random sizes and distributions. Response surface approximations were formulated based on void parameters such as area and length fractions to provide an estimate of the effective stiffness. Obtaining quantitative relationships between the properties of the voids and their effects on stiffness of ceramic matrix composites are of ultimate interest, but the exploratory study presented here starts by first modeling the effects of voids on an isotropic material. Several cases with varying void parameters were modeled which resulted in a large amount of variability of the transverse stiffness and out-of-plane shear stiffness. An investigation into a physical explanation for the stiffness degradation led to the observation that the voids need to be treated as an entity that reduces load bearing capabilities in a space larger than what the void directly occupies through a corrected length fraction or area fraction. This provides explanation as to why void volume fraction is not the only important factor to consider when computing loss of stiffness.

  18. Collaborating with Space-related Research Institutes, Government Agencies and an Artistic team to create a series of Space-themed public events in Ireland in 2014

    Science.gov (United States)

    Shaw, N.; McSweeney, C.; Smyth, N.; O'Neill, S.; Foley, C.; Phelan, R.; Crawley, J.; Henderson, C.; Cullinan, M.; Baxter, S.; Colley, D.; Macaulay, C. J.; Conroy, L.

    2015-10-01

    A suite of informal interactive public engagement initiatives was created, to promote the importance of Space exploration, to ignite curiosity and discover new and engaging platforms for science in the Arts & in STEM Education, and to increase awareness of careers in Ireland's Space science industries. These included: (1)'To Space'- A live multimedia theatre performance aimed at the general public & young adult, (2) an adaptation of 'To Space' for 13- 17 year old students entitled 'ToSpace for School leavers' and (3) 'My Place in Space', created for families. Blending humour, warmth and humanity and positioning science within story is a highly effective public engagement tool in igniting curiosity across many audience types. The nurturing and investment of artists working within these new cross-disciplinary relationships should be encouraged and supported to further broaden and develop new methodology in public engagement of the planetary sciences.

  19. Into the Void

    Science.gov (United States)

    2006-01-01

    17 May 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a portion of a chain of pits on a lava- and dust-covered plain northwest of Tharsis Tholus -- one of the many volcanic constructs in the Tharsis region of Mars. Pit chains, such as this one, are associated with the collapse of surface materials into subsurface voids formed by faulting and expansion -- or extension -- of the bedrock. Location near: 16.4oN, 92.6oW Image width: 3 km (1.9 mi) Illumination from: lower left Season: Northern Winter

  20. A space for mothers: grief as identity construction on memorial websites created by SIDS parents.

    Science.gov (United States)

    Finlay, Christopher J; Krueger, Guenther

    2011-01-01

    In this article we conduct a textual analysis of memorial websites created by mothers who have experienced a loss due to sudden infant death syndrome (SIDS). Using an online Internet ethnographic approach, we reviewed a series of 20 sites in an attempt to analyze the motivations of the site creators as manifested in their online projects. We spent time on the sites, moving through all facets of them, following links, and experiencing them the way a visitor would encounter them. In this virtual exploration we uncovered personal narratives, community building, religious imagery, and numerous examples of social networking. We also analyzed guest books in order to understand who visits these sites and their reasons for doing so. We conclude that development of these sites are a process that helps some mothers in their grief and gives them a focus and activity that is helpful and perhaps healing. More importantly perhaps is the potential for community building and networking that this type of activity allows. As an extension of a real-world memorial such as a gravesite, a virtual mourning space provides more in the way of these types of communications. Our work suggests that memorial websites constructed by SIDS parents help in meaning and identity reconstruction after loss.

  1. Irregularities Associated with Artificially Created Dusty Plasmas in the near Earth Space Environment

    Science.gov (United States)

    Bordikar, M. R.; Scales, W.; Mahmoudian, A.; Fu, H.

    2009-12-01

    A natural dust layer formed by tons of meteoric dust spans the altitude range between 80 and 100 kilometers of the earth’s upper mesosphere and lower thermosphere which forms Noctilucent Clouds NLCs. These dust layers are charged due to collection of electrons and ions from the earth’s ionosphere. Polar Mesospheric Summer Echoes are radar echoes which result from scattering from the irregularities in the electron density above the NLC altitude. An alternate approach to understanding natural dust layers is to perform active space experiments in which a dust cloud is artificially created in a controlled manner in the upper atmosphere. The goal of Charged Aerosol Release Experiment (CARE) is to investigate similarity in plasma irregularity associated with natural and artificial dust layers. This presentation will address some of the physical processes expected to be important during the early time phase after creation of an artificial dust cloud in the earth’s ionosphere. Of major importance will be the production of plasma irregularities which may lead to radar echoes and the possibility of their relationship to PMSEs observed from natural dusty space plasmas. The objective is to investigate the production of electron irregularities due to growth of plasma instabilities driven by inhomogeneities in the boundary between the background plasma and the expanding charged dust layer. First, a two dimensional plasma simulation model will be described that may be used for examining early time evolution after expansion of an artificial dust cloud across the magnetic field in the ionosphere. The model considers a three species system with fluid electrons and ions and Particle-In-Cell PIC charged dust grains in which the dust charge on the grains varies in time according to the standard charging model. The electrons are magnetized and the algorithm incorporates the parallel electron dynamics while the ions are assumed to be unmagnetized. Simulations runs were made to

  2. South Dakota NASA Space Grant Consortium Creating Bridges in Indian Country

    Science.gov (United States)

    Bolman, J. R.

    2004-12-01

    The South Dakota Space Grant Consortium (SDSGC) was established March 1, 1991 by a NASA Capability Enhancement Grant. Since that time SDSGC has worked to provide earth and space science educational outreach to all students across South Dakota. South Dakota has nine tribes and five tribal colleges. This has presented a tremendous opportunity to develop sustainable equitable partnerships and collaborations. SDSGC believes strongly in developing programs and activities that highlight the balance of indigenous science and ways of knowing with current findings in contemporary science. This blending of science and culture creates a learning community where individuals, especially students, can gain confidence and pride in their unique skills and abilities. Universities are also witnessing the accomplishments and achievements of students who are able to experience a tribal college environment and then carry that experience to a college/university/workplace and significantly increase the learning achievement of all. The presentation will highlight current Tribal College partnerships with Sinte Gleska University and Oglala Lakota College amongst others. Programs and activities to be explained during the presentation include: Native Connections, Scientific Knowledge for Indian Learning and Leadership (SKILL), Bridges to Success Summer Research Program, Fire Ecology Summer Experience, and dual enrolled/college bridge programs. The presentation will also cover the current initiatives underway through NASA Workforce Development. These include: partnering program with the Annual He Sapa Wacipi, American Indian Space Days 2005, NASA research/internship programs and NASA Fellow Summit. An overview of recent American Indian student success will conclude the presentation. The South Dakota School of Mines and Technology has struggled over many years to develop and implement sustainable successful initiatives with Tribal Colleges and Communities. The motivating philosophy is the

  3. CTF Void Drift Validation Study

    Energy Technology Data Exchange (ETDEWEB)

    Salko, Robert K. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gosdin, Chris [Pennsylvania State Univ., University Park, PA (United States); Avramova, Maria N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Gergar, Marcus [Pennsylvania State Univ., University Park, PA (United States)

    2015-10-26

    This milestone report is a summary of work performed in support of expansion of the validation and verification (V&V) matrix for the thermal-hydraulic subchannel code, CTF. The focus of this study is on validating the void drift modeling capabilities of CTF and verifying the supporting models that impact the void drift phenomenon. CTF uses a simple turbulent-diffusion approximation to model lateral cross-flow due to turbulent mixing and void drift. The void drift component of the model is based on the Lahey and Moody model. The models are a function of two-phase mass, momentum, and energy distribution in the system; therefore, it is necessary to correctly model the ow distribution in rod bundle geometry as a first step to correctly calculating the void distribution due to void drift.

  4. Creating "Invited" Spaces for Counter-Radicalization and Counter-Extremism Education

    Science.gov (United States)

    Arshad-Ayaz, Adeela; Naseem, M. Ayaz

    2017-01-01

    In this article we present an articulation of how "invited spaces" can foster inclusive and authentic participation and public discourse on issues related to extremism and radicalization. Conversations on these issues that are of crucial importance to the general public are usually held in closed spaces or in spaces that are set up by…

  5. Creating "Invited" Spaces for Counter-Radicalization and Counter-Extremism Education

    Science.gov (United States)

    Arshad-Ayaz, Adeela; Naseem, M. Ayaz

    2017-01-01

    In this article we present an articulation of how "invited spaces" can foster inclusive and authentic participation and public discourse on issues related to extremism and radicalization. Conversations on these issues that are of crucial importance to the general public are usually held in closed spaces or in spaces that are set up by…

  6. Getting beyond "I Like the Book": Creating Space for Critical Literacy in K-6 Classrooms. Second Edition

    Science.gov (United States)

    Vasquez, Vivian

    2010-01-01

    "Getting Beyond "I Like the Book": Creating Space for Critical Literacy in K-6 Classrooms" (second edition) draws you into life in classrooms where students and teachers together use critical literacy as a framework for taking on local and global issues like racism and gender using books and everyday texts such as school posters and…

  7. My Space- a collaboration between Arts & Science to create a suite of informal interactive public engagement initiatives.

    Science.gov (United States)

    Shaw, Niamh, , Dr.; McSweeney, Clair; Smith, Niall, , Dr.; O'Neill, Stephanie; Foley, Cathy; Crawley, Joanna; Phelan, Ronan; Colley, Dan; Henderson, Clare; Conroy, Lorraine

    2015-04-01

    A suite of informal interactive public engagement initiatives, entitled 'MySpace' was created, to promote the importance of Earth science and Space exploration, to ignite curiosity and discover new and engaging platforms for science in the Arts & in STEM Education, and to increase awareness of careers in Ireland's Space and Earth Science industries. Site visits to research centres in Ireland & abroad, interviews with scientists, engineers, and former astronauts were conducted over a 6 month period. A suite of performance pieces emerged from this development phase, based on Dr. Shaw's personal documented journey and the dissemination of her research. These included: 1. 'To Space'- A live multimedia theatre performance aimed at the general public & young adult. Initially presented as a 'Work In Progress' event at The Festival of Curiosity, the full theatre show 'To Space' premiered at Science Gallery, Dublin as part of Tiger Dublin Fringe Arts Festival. Response to the piece was very strong, indicated by audience response, box office sales and theatre reviews in national press and online. A national and international tour is in place for 2015. To Space was performed a total of 10 times and was seen by 680 audiences. 2. An adapted piece for 13-17 year old students -'ToSpace for Secondary Schools'- to increase awareness of Ireland's involvement in Space Exploration & to encourage school leavers to dream big. This show toured nationally as part of World Space week and Science week events in conjunction with ESERO Ireland, CIT Blackrock Castle Observatory, Cork, Armagh Planetarium & Dunsink Observatory. It was performed 12 times and was seen by 570 students. 3. 'My Place in Space', created for families from the very old (60 +) to the very young (3yrs +), this highly interactive workshop highlighted the appeal of science through the wonders of our planet and its place in Space. Presented at Festival of Curiosity, the Mallow Science Fair and at Science week 2014, this

  8. Urethane foam void filling. Innovative technology summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-12-01

    Under the decontamination and decommissioning (D and D) Implementation Plan of the United States Department of Energy`s (DOE`s) Fernald Environmental Management Project (FEMP), non-recyclable process components and debris that are removed from buildings undergoing D and D are disposed of in an on-site disposal facility (OSDF). Critical to the design and operation of the FEMP`s OSDF are provisions to protect against subsidence of the OSDF`s cap. Subsidence of the cap could occur if void spaces within the OSDF were to collapse under the overburden of debris and the OSDF cap. Subsidence may create depressions in the OSDF`s cap in which rainwater could collect and eventually seep into the OSDF. To minimize voids in the FEMP`s OSDF, large metallic components are cut into smaller segments that can be arranged more compactly when placed in the OSDF. Component segmentation using an oxy-acetylene torch was the baseline approach used by the FEMP`s D and D contractor on Plant 1, B and W Services, Inc., for the dismantlement and size-reduction of large metal components. Although this technology has performed satisfactorily, it is time-consuming, labor-intensive and costly. Use of the oxy-acetylene torch exposes workers to health and safety hazards including the risk of burns, carbon monoxide, and airborne contamination of residual lead-based paints and other contaminants on the surface of the components being segmented. In addition, solvents used to remove paint from the components before segmenting them emit flammable, noxious fumes. This demonstration investigated the feasibility of placing large vessels intact in the OSDF without segmenting them. To prevent the walls of the vessels from collapsing under the overburden or from degradation, an innovative approach was employed which involved filling the voids in the vessels with a fluid material that hardened on standing. The hardened filling would support the walls of the vessels, and prevent them from collapsing. This report

  9. Creating a "Third Space" in Student Teaching: Implications for the University Supervisor's Status as Outsider

    Science.gov (United States)

    Cuenca, Alexander; Schmeichel, Mardi; Butler, Brandon M.; Dinkelman, Todd; Nichols, Joseph R., Jr.

    2011-01-01

    The work of teacher education during student teaching typically takes place in two distinct "spaces": placement sites and college/university settings. The program featured in this article is structured in ways that clearly mark out those two spaces. Yet this configuration led our university supervisors, whose work primarily took place in the…

  10. Using Email Interviews in Qualitative Educational Research: Creating Space to Think and Time to Talk

    Science.gov (United States)

    James, Nalita

    2016-01-01

    The article explores how the Internet and email offer space for participants to think and make sense of their experiences in the qualitative research encounter. It draws on a research study that used email interviewing to generate online narratives to understand academic lives and identities through research encounters in virtual space. The…

  11. The Context of Creating Space: Assessing the Likelihood of College LGBT Center Presence

    Science.gov (United States)

    Fine, Leigh E.

    2012-01-01

    LGBT (lesbian, gay, bisexual, and transgender) resource centers are campus spaces dedicated to the success of sexual minority students. However, only a small handful of American colleges and universities have such spaces. Political opportunity and resource mobilization theory can provide a useful framework for understanding what contextual factors…

  12. The Context of Creating Space: Assessing the Likelihood of College LGBT Center Presence

    Science.gov (United States)

    Fine, Leigh E.

    2012-01-01

    LGBT (lesbian, gay, bisexual, and transgender) resource centers are campus spaces dedicated to the success of sexual minority students. However, only a small handful of American colleges and universities have such spaces. Political opportunity and resource mobilization theory can provide a useful framework for understanding what contextual factors…

  13. Using Email Interviews in Qualitative Educational Research: Creating Space to Think and Time to Talk

    Science.gov (United States)

    James, Nalita

    2016-01-01

    The article explores how the Internet and email offer space for participants to think and make sense of their experiences in the qualitative research encounter. It draws on a research study that used email interviewing to generate online narratives to understand academic lives and identities through research encounters in virtual space. The…

  14. Creating Interdisciplinary Space on Campus: Lessons from US Area Studies Centers

    Science.gov (United States)

    Friedman, Jonathan Z.; Worden, Elizabeth Anderson

    2016-01-01

    Recent calls for university administrators to advance interdisciplinary research and teaching have suggested that allocating campus space to such initiatives is key to their success. Yet questions remain concerning just what kinds of spaces are most conducive to this agenda. This article aims to shed light on this relationship by drawing on case…

  15. Testing Gravity using Void Profiles

    Science.gov (United States)

    Cai, Yan-Chuan; Padilla, Nelson; Li, Baojiu

    2016-10-01

    We investigate void properties in f(R) models using N-body simulations, focusing on their differences from General Relativity (GR) and their detectability. In the Hu-Sawicki f(R) modified gravity (MG) models, the halo number density profiles of voids are not distinguishable from GR. In contrast, the same f(R) voids are more empty of dark matter, and their profiles are steeper. This can in principle be observed by weak gravitational lensing of voids, for which the combination of a spectroscopic redshift and a lensing photometric redshift survey over the same sky is required. Neglecting the lensing shape noise, the f(R) model parameter amplitudes fR0=10-5 and 10-4 may be distinguished from GR using the lensing tangential shear signal around voids by 4 and 8 σ for a volume of 1 (Gpc/h)3. The line-of-sight projection of large-scale structure is the main systematics that limits the significance of this signal for the near future wide angle and deep lensing surveys. For this reason, it is challenging to distinguish fR0=10-6 from GR. We expect that this can be overcome with larger volume. The halo void abundance being smaller and the steepening of dark matter void profiles in f(R) models are unique features that can be combined to break the degeneracy between fR0 and σ8.

  16. The Void Galaxy Survey: Morphology and Star Formation Properties of Void Galaxies

    CERN Document Server

    Beygu, B; van der Hulst, J M; Peletier, R; Jarrett, T; van de Weygaert, R; van Gorkom, J H; Aragón-Calvo, M

    2015-01-01

    We present the structural and star formation properties of 59 void galaxies as part of the Void Galaxy Survey (VGS). Our aim is to study in detail the physical properties of these void galaxies and study the effect of the void environment on galaxy properties. We use Spitzer 3.6 $\\rm{\\mu m}$ and B-band imaging to study the morphology and color of the VGS galaxies. For their star formation properties, we use Halpha and GALEX near-UV imaging. We compare our results to a range of galaxies of different morphologies in higher density environments. We find that the VGS galaxies are in general disk dominated and star forming galaxies. Their star formation rates are, however, often less than 1 $\\rm{M_{\\odot}}$ $\\rm{yr^{-1}}$. There are two early-type galaxies in our sample as well. In $\\rm{r_{e}}$ versus $\\rm{M_{B}}$ parameter space, VGS galaxies occupy the same space as dwarf irregulars and spirals.

  17. Exploitation of Simple Classification and Space Created by the Tumor for the Treatment of Foramen Magnum Meningiomas.

    Science.gov (United States)

    Yamahata, Hitoshi; Yamaguchi, Satoshi; Takayasu, Masakazu; Takasaki, Koji; Osuka, Koji; Aoyama, Masahiro; Yasuda, Muneyoshi; Tokimura, Hiroshi; Kurisu, Kaoru; Arita, Kazunori

    2016-03-01

    The resection of foramen magnum meningiomas (FMMs) presents neurosurgical challenges. We propose a simple classification of the tumor location and the operating space created by the tumor to help treatment planning. We retrospectively analyzed 16 FMMs and divided them into 3 groups based on the tumor location--clival, foraminal, and atlantal tumors. The distance between the condyle and the neuraxis at the level of the foramen magnum was measured and defined as the available operative space (AOS). We also reviewed intraoperative video recordings to assess the surgical exposure of the tumor by the space created by the FMM and compared it with the AOS. There were 4 clival, 8 foraminal, and 4 atlantal tumors. The AOS of the clival tumors was 10 mm ± 1.7, the AOS of the foraminal tumors was 18 mm ± 3.7, and the AOS of the atlantal tumors was 12 mm ± 2.1. All foraminal and atlantal tumors could be detached without a brain retractor. Because a major portion of the clival tumors was covered by the spinomedullary junction, a brain spatula was needed to obtain the required surgical space. The difference in AOS between clival and foraminal/atlantal tumors was statistically significant (P = 0.044). Although 4 patients experienced postoperative complications, the average postoperative Karnofsky performance scale score improved. The surgical complication rate was significantly lower in foraminal and atlantal FMMs than in clival FMMs (P = 0.027). The simple classification of the tumor location helped to assess surgical difficulties. Knowledge of the space created by the FMMs between the condyle and the neuraxis is useful for planning the approach strategy, especially for estimating the available working space without resection of the occipital condyle. Copyright © 2016 Elsevier Inc. All rights reserved.

  18. When creating new learning spaces, the affordance is a key study aspect

    DEFF Research Database (Denmark)

    Dau, Susanne

    2013-01-01

    and individual knowledge development. Through analysis of empirical data, gained through a pragmatic mixed method approach, is the role of different face-to-face as well as online spaces investigated in the view of students, lectures and practitioners understanding. The major findings regards spaces contribution...... to sociality, identity, referential embodied experiences as having huge influence on students’ preferences and learning activity. The results are addressed to learning and knowledge development. It´s concluded, that individual as well as social constructed learning make influence, and are influenced......This research aims to highlight, how different places and spaces in undergraduate education afford students learning, and development of certain types of knowledge. The question, that this paper address is: What is the affordance of different learning spaces in flexible undergraduate education...

  19. Scaling of voids and fractality in the galaxy distribution

    CERN Document Server

    Gaite, J; Gaite, Jose; Manrubia, Susanna C.

    2002-01-01

    We study here, from first principles, what properties of voids are to be expected in a fractal point distribution and how the void distribution is related to its morphology. We show this relation in various examples and apply our results to the distribution of galaxies. If the distribution of galaxies forms a fractal set, then this property results in a number of scaling laws to be fulfilled by voids. Consider a fractal set of dimension $D$ and its set of voids. If voids are ordered according to decreasing sizes (largest void has rank R=1, second largest R=2 and so on), then a relation between size $\\Lambda$ and rank of the form $\\Lambda (R) \\propto R^{-z}$ must hold, with $z = d/D$, and where $d$ is the euclidean dimension of the space where the fractal is embedded. The physical restriction $D 1$ in a fractal set. The average size $\\bar \\Lambda$ of voids depends on the upper ($\\Lambda_u$) and the lower ($\\Lambda_l$) cut-off as ${\\bar \\Lambda} \\propto \\Lambda_u^{1-D/d} \\Lambda_l^{D/d}$. Current analysis of v...

  20. The Transformation of Ms. Corazon: Creating Humanizing Spaces for Mexican Immigrant Students in Secondary ESL Classrooms

    Science.gov (United States)

    Salazar, Maria del Carmen; Franquiz, Maria E.

    2008-01-01

    This article explores the journey of one English as a Second Language (ESL) teacher who held rigid boundaries that negatively impacted the academic resiliency of her Mexican immigrant students. As she transformed her pedagogical orientation, she created permeability in her curricular practices. With the elements of "respeto" (respect), "confianza"…

  1. What Stick Figures Tell Us about Irish Politics: Creating a Critical and Collaborative Learning Space

    Science.gov (United States)

    Feeney, Sharon; Hogan, John; Donnelly, Paul F.

    2015-01-01

    This paper focuses upon the interpretation of freehand drawings produced by a small sample of 220 first-year students taking an Irish politics introductory module in response to the question, "What is Irish Politics?" By sidestepping cognitive verbal-processing routes, through employing freehand drawing, we aim to create a critical and…

  2. The Transformation of Ms. Corazon: Creating Humanizing Spaces for Mexican Immigrant Students in Secondary ESL Classrooms

    Science.gov (United States)

    Salazar, Maria del Carmen; Franquiz, Maria E.

    2008-01-01

    This article explores the journey of one English as a Second Language (ESL) teacher who held rigid boundaries that negatively impacted the academic resiliency of her Mexican immigrant students. As she transformed her pedagogical orientation, she created permeability in her curricular practices. With the elements of "respeto" (respect), "confianza"…

  3. The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms.

    Directory of Open Access Journals (Sweden)

    Austin T Humphries

    Full Text Available Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and "predator-free space" to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio in the presence of a predator (wild red drum, Sciaenops ocellatus was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of "predator-free space" was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require "predator-free space" measures that also account for the available area within the structure itself (i.e., volume and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of "predator-free space" are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

  4. Geometry and scaling of cosmic voids

    CERN Document Server

    Gaite, Jose

    2008-01-01

    CONTEXT: Cosmic voids are observed in the distribution of galaxies and, to some extent, in the dark matter distribution. If these distributions have fractal geometry, it must be reflected in the geometry of voids; in particular, we expect scaling sizes of voids. However, this scaling is not well demonstrated in galaxy surveys yet. AIMS: Our objective is to understand the geometry of cosmic voids in relation to a fractal structure of matter. We intend to distinguish monofractal voids from multifractal voids, regarding their scaling properties. We plan to analyse voids in the distributions of mass concentrations (halos) in a multifractal and their relation to galaxy voids. METHODS: We make a statistical analysis of point distributions based on the void probability function and correlation functions. We assume that voids are spherical and devise a simple spherical void finder. For continuous mass distributions, we employ the methods of fractal geometry. We confirm the analytical predictions with numerical simula...

  5. When creating new learning spaces, the affordance is a key study aspect

    DEFF Research Database (Denmark)

    Dau, Susanne

    2013-01-01

    in learning spaces. The students embodied interaction is both in references to past experiences, as well as under development towards a fictive future, which is both a result of their preferences and of their engagement. On the basis of the concept of affordance, and the frame of social-cultural theory...

  6. Organic Activists: Undocumented Youth Creating Spaces of Acompañamiento

    Science.gov (United States)

    Nuñez-Janes, Mariela; Ovalle, Mario

    2016-01-01

    Our research brings attention to undocumented youth activism as a space controlled by marginalized youth. We discuss the case study of a youth-led grassroots group in Texas to explore how undocumented youth engage a pedagogy of acompañamiento through activism. We worked with undocumented youth activists as allies over the past seven years and…

  7. Does Digitized Virtual Space Allow for Effective Learning in Creating Environments for Theatrical Productions?

    Science.gov (United States)

    Magruder, Lewis

    2016-01-01

    Learning how to transform an empty space into one alive with dramatic possibilities is one of the challenges facing students in several disciplines--for example, graphic design, filmmaking, gaming, architecture, interior design, visual arts, and designing and directing for the theatre. The author, a professor of directing for the theatre,…

  8. Creating Inclusive Physical Activity Spaces: The Case of Body-Positive Yoga

    Science.gov (United States)

    Pickett, Andrew C.; Cunningham, George B.

    2017-01-01

    Purpose: Within the modern cultural climate, those in larger bodies face high levels of weight stigma, particularly in sport and physical activity spaces, which serves as a strong barrier to their participation. However, given the strong link between physical activity and general health and well-being for participants, it is important to explore…

  9. Does Digitized Virtual Space Allow for Effective Learning in Creating Environments for Theatrical Productions?

    Science.gov (United States)

    Magruder, Lewis

    2016-01-01

    Learning how to transform an empty space into one alive with dramatic possibilities is one of the challenges facing students in several disciplines--for example, graphic design, filmmaking, gaming, architecture, interior design, visual arts, and designing and directing for the theatre. The author, a professor of directing for the theatre,…

  10. Creating the Public Connection: Interactive Experiences with Real-Time Earth and Space Science Data

    Science.gov (United States)

    Reiff, Patricia H.; Ledley, Tamara S.; Sumners, Carolyn; Wyatt, Ryan

    1995-01-01

    The Houston Museum of Natural Sciences is less than two miles from Rice University, a major hub on the Internet. This project links these two institutions so that NASA real-time data and imagery can flow via Rice to the Museum where it reaches the public in the form of planetarium programs, computer based interactive kiosks, and space and Earth science problem solving simulation. Through this program at least 200,000 visitors annually (including every 4th and 7th grader in the Houston Independent School District) will have direct exposure to the Earth and space research being conducted by NASA and available over the Internet. Each information conduit established between Rice University and the Houston Museum of Natural Science will become a model for public information dissemination that can be replicated nationally in museums, planetariums, Challenger Centers, and schools.

  11. Creating State-based Alliances to Support Earth and Space Science Education Reform

    Science.gov (United States)

    Geary, E. E.; Manduca, C. A.; Barstow, D.

    2002-05-01

    Seven years after the publication of the National Science Education Standards and adoption of new state science education standards, Earth and space science remains outside the mainstream K-12 curriculum. Currently, less than ten percent of high school students in the United States of America take an Earth or space science course before graduation. This state of affairs is simply unacceptable. "All of us who live on this planet have the right and the obligation to understand Earth's unique history, its dynamic processes, its abundant resources, and its intriguing mysteries. As citizens of Earth, with the power to modify our climate and ecosystems, we also have a personal and collective responsibility to understand Earth so that we can make wise decisions about its and our future". As one step toward addressing this situation, we support the establishment of state-based alliances to promote Earth and space science education reform. "In many ways, states are the most vital locus of change in our nation's schools. State departments of education define curriculum frameworks, establish testing policies, support professional development and, in some cases, approve textbooks and materials for adoption". State alliance partners should include a broad spectrum of K-16 educators, scientists, policy makers, parents, and community leaders from academic institutions, businesses, museums, technology centers, and not-for profit organizations. The focus of these alliances should be on systemic and sustainable reform of K-16 Earth and space science education. Each state-based alliance should focus on specific educational needs within their state, but work together to share ideas, resources, and models for success. As we build these alliances we need to take a truly collaborative approach working with the other sciences, geography, and mathematics so that collectively we can improve the caliber and scope of science and mathematics education for all students.

  12. Creating Assemblies in Media Space: Recent Developments in Enhancing Access to Workspaces

    Science.gov (United States)

    Luff, Paul; Kuzuoka, Hideaki; Heath, Christian; Yamazaki, Keiichi; Yamashita, Jun

    In this chapter, we discuss a programme of social and technical research that we have undertaken over the last few years concerned with the design, assessment and development of systems to support real-time, distributed work; work that relies upon a participants' ability to access a range of tangible and digital resources. The programme of work has been informed by findings from a range of studies of work and collaboration in environments that include architectural practices, control centres, surgeries, hospitals, news rooms, and the like. These studies have a framework of considerations, criteria, and insights into the organization of everyday work and interaction that have enabled us to identify some of the limitations of con¬ventional media spaces, including systems which we have helped develop, and to pose a set of requirements and challenges, which we believe are fundamental to the creation of a media space that could support the flexible and contingent demands of seemingly simple forms of collaborative work. These studies, coupled with the development and assessment of a series of experimental systems, have enabled us to identify three key issues that we believe have to be addressed and resolved (in one way or another) if media space research is going to achieve its early potential.

  13. PREREQUISITES FOR CREATING THE IMAGE OF IRAQ IN THE NETWORK SPACE OF THE RUSSIAN METROPOLIS

    Directory of Open Access Journals (Sweden)

    G. N. TROFIMOVA

    2015-01-01

    Full Text Available One of the leading trends in modern mega-polis has become a strong preference of online media to the traditional format and the formation of the picture of the world with their help. The article focuses on the complex study of cultural, political and informational preconditions for the formation of the image of Iraq among the Internet audience in Russia. The author names the main publications that impact the formation of the image of Iraq in the Russian network space, notes special features of Russian Internet-audience and the impact of these features on the formation of the overall image of Iraq in the information space of Russian media. As an example, the author relies on the quotes from the leading Russian publications and online information resources and historical relationships of two countries. In addition, the authoranalyzes the key features of the formation of the image of a foreign country in the context of the Russian media and comes to the conclusion that the image of Iraq is formed mainly on network news resources, which often have political overtones, excluding the historical and cultural context. Results of the study suggest that the image of a foreign country is formed mainly in the network space.

  14. Alignment of voids in the cosmic web

    NARCIS (Netherlands)

    Platen, Erwin; van de Weygaert, Rien; Jones, Bernard J. T.

    2008-01-01

    We investigate the shapes and mutual alignment of voids in the large-scale matter distribution of a Lambda cold dark matter (Lambda CDM) cosmology simulation. The voids are identified using the novel watershed void finder (WVF) technique. The identified voids are quite non-spherical and slightly pro

  15. Alignment of voids in the cosmic web

    NARCIS (Netherlands)

    Platen, Erwin; van de Weygaert, Rien; Jones, Bernard J. T.

    2008-01-01

    We investigate the shapes and mutual alignment of voids in the large-scale matter distribution of a Lambda cold dark matter (Lambda CDM) cosmology simulation. The voids are identified using the novel watershed void finder (WVF) technique. The identified voids are quite non-spherical and slightly

  16. Plasticity size effects in voided crystals

    DEFF Research Database (Denmark)

    Hussein, M. I.; Borg, Ulrik; Niordson, Christian Frithiof

    singularities in an elastic material. The lattice resistance to dislocation motion, dislocation nucleation, dislocation interaction with obstacles and annihilation are incorporated through a set of constitutive rules. Over the range of length scales investigated, both the discrete dislocation and strain...... predictions of the two formulations for all crystal types and void volume fractions considered when the material length scale in the non-local plasticity model chosen to be $0.325\\mu m$ (around ten times the slip plane spacing in the discrete dislocation models)....

  17. Plasticity size effects in voided crystals

    DEFF Research Database (Denmark)

    Hussein, M.I.; Borg, Ulrik; Niordson, Christian Frithiof

    2008-01-01

    as line singularities in an elastic material. The lattice resistance to dislocation motion, dislocation nucleation, dislocation interaction with obstacles and annihilation are incorporated through a set of constitutive rules. Over the range of length scales investigated, both the discrete dislocation...... between predictions of the two formulations for all crystal types and void volume fractions considered when the material length scale in the non-local plasticity model is chosen to be 0.325 mu m (about 10 times the slip plane spacing in the discrete dislocation models)....

  18. Workplace learning from a socio-cultural perspective: creating developmental space during the general practice clerkship.

    Science.gov (United States)

    van der Zwet, J; Zwietering, P J; Teunissen, P W; van der Vleuten, C P M; Scherpbier, A J J A

    2011-08-01

    Workplace learning in undergraduate medical education has predominantly been studied from a cognitive perspective, despite its complex contextual characteristics, which influence medical students' learning experiences in such a way that explanation in terms of knowledge, skills, attitudes and single determinants of instructiveness is unlikely to suffice. There is also a paucity of research which, from a perspective other than the cognitive or descriptive one, investigates student learning in general practice settings, which are often characterised as powerful learning environments. In this study we took a socio-cultural perspective to clarify how students learn during a general practice clerkship and to construct a conceptual framework that captures this type of learning. Our analysis of group interviews with 44 fifth-year undergraduate medical students about their learning experiences in general practice showed that students needed developmental space to be able to learn and develop their professional identity. This space results from the intertwinement of workplace context, personal and professional interactions and emotions such as feeling respected and self-confident. These forces framed students' participation in patient consultations, conversations with supervisors about consultations and students' observation of supervisors, thereby determining the opportunities afforded to students to mind their learning. These findings resonate with other conceptual frameworks and learning theories. In order to refine our interpretation, we recommend that further research from a socio-cultural perspective should also explore other aspects of workplace learning in medical education.

  19. Three-dimensional investigation of grain orientation effects on void growth in commercially pure titanium

    Energy Technology Data Exchange (ETDEWEB)

    Pushkareva, Marina [Department of Mechanical Engineering, University of Ottawa, 150 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Adrien, Jérôme; Maire, Eric [Université de Lyon, INSA-Lyon, MATEIS CNRS UMR5510, 7 Avenue Jean Capelle, F-69621 Villeurbanne (France); Segurado, Javier; Llorca, Javier [IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Department of Materials Science, Polytechnic University of Madrid, E. T. S. de Ingenieros de Caminos, 28040 Madrid (Spain); Weck, Arnaud, E-mail: aweck@uottawa.ca [Department of Mechanical Engineering, University of Ottawa, 150 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); IMDEA Materials Institute, C/Eric Kandel 2, 28906 Getafe, Madrid (Spain); Department of Physics, University of Ottawa, 150 Louis Pasteur, Ottawa, ON, Canada K1N 6N5 (Canada); Centre for Research in Photonics at the University of Ottawa, 800 King Edward Ave., Ottawa, ON, Canada K1N 6N5 (Canada)

    2016-08-01

    The fracture process of commercially pure titanium was visualized in model materials containing artificial holes. These model materials were fabricated using a femtosecond laser coupled with a diffusion bonding technique to obtain voids in the interior of titanium samples. Changes in void dimensions during in-situ straining were recorded in three dimensions using x-ray computed tomography. Void growth obtained experimentally was compared with the Rice and Tracey model which predicted well the average void growth. A large scatter in void growth data was explained by differences in grain orientation which was confirmed by crystal plasticity simulations. It was also shown that grain orientation has a stronger effect on void growth than intervoid spacing and material strength. Intervoid spacing, however, appears to control whether the intervoid ligament failure is ductile or brittle.

  20. The role of public spaces in creating place attachment (example of Zacisze, Warsaw housing estate

    Directory of Open Access Journals (Sweden)

    Mantey Dorota

    2015-09-01

    Full Text Available This article raises the question of place attachment in the context of an increasingly important factor, that is the use of gathering and leisure places. The author publishes findings of a survey conducted among the residents of Zacisze, Warsaw, a detached housing estate with a very poor range of public places for gathering and leisure. The study has proved that the use of local public spaces, as a specific category of place, reinforces attachment to the whole housing estate. The study also confirms the important role that social factors have in building place attachment. Conditions already exist for considering social factors more important than physical ones in building a positive relationship with a territory.

  1. The School Bus Symposium: A Poetic Journey of Co-created Conference Space

    Directory of Open Access Journals (Sweden)

    Mitchell A McLarnon

    2016-07-01

    Full Text Available With the intention of disrupting and re-imagining traditional conference spaces, this article is a poetic compilation developed from a Curriculum Studies conference symposium that took place on a school bus. During the School Bus Symposium, in situ poetry writing and reading, song and storytelling occurred in response to open ended prompts and facilitation of creative activities. After the symposium, a call was issued to invite participants to submit any poetry or stories produced during, or inspired by the session. Consisting of 18 submissions including poetry, story, photography and creative essays, infused by curriculum theory and poetic inquiry, this collection offers an inclusive, reflective, participatory, and experiential rendering where participants are living and journeying poetically. Emphasizing creative engagement with personal memories, the authors collectively aimed to promote art education through imaginative approaches to curriculum studies, poetic inquiry and academic conferences.

  2. Vinyl by design: creating interior spaces that stand the test of time.

    Science.gov (United States)

    2002-01-01

    Managing design liability, avoiding risk and providing successful buildings are founded upon a conscious awareness of many important details. A key component of a designer's professionalism is understanding potential problems before they occur and proactively specifying the solutions to them. Familiarity with the inherent characteristics of any building material, along with the performance capabilities of specifiable products made with that material, aids in this process. Documenting the selection of a product in the project specifications should take this understanding into account. Knowing the important role of proper product installation--and, where necessary, calling upon the expertise of product manufacturers--should not be underestimated. Each part of the process has a major impact on whether the interior spaces delivered to a building owner provide lasting gratification, value, user satisfaction and recognition of the design professional's strategic importance to the project's overall success.

  3. Kennedy Space Center: Creating a Spaceport Reality from the Dreams of Many

    Science.gov (United States)

    Gray, James A.; Colloredo, Scott

    2012-01-01

    On December 17, 1903, Orville Wright piloted the first powered airplane only 20 feet above the ground near Kitty Hawk, North Carolina. The flight lasted 12 seconds and covered 120 feet. Who would have guessed that the bizarre looking contraption developed by brothers in the bicycle business would lay the ground work eventually resulting in over a million passengers moved daily in a sky filled with the contrails of jets flying at over 30,000 feet in elevation and over 500 miles per hour. Similarly, who would have guessed that the destructive nature of V-2 rockets of Germany would spark the genesis of spaceflight to explore our solar system and beyond? Yet the interest in using the Kennedy Space Center (KSC) continues to grow. Potential customers have expressed interest in KSC as a location for testing new rocket engines, servicing the world's largest airborne launching platform for drop-launch rockets, developing multi-use launch platforms that permit diverse customers to use the same launch platform, developing new spacecraft, and implementing advanced modifications for lifting 150 metric ton payloads to low earth orbit. The multitude of customers has grown and with this growth comes a need to provide a command, control, communication, and range infrastructure that maximizes flexibility and reconfigurability to address a much more frequent launch rate of diverse vehicles and spacecraft. The Ground Systems Development and Operations (GSDO) Program Office at KSC is embarking upon these developments to realize the dream of a robust spaceport. Many unique technical trade studies have been completed or are underway to successfully transition KSC into a multi-user customer focused spaceport. Like the evolution of the airplane, GSDO is working to transform KSC infrastructures that will turn once unthinkable space opportunities into a reality for today.

  4. Large-scale floor heater creating a comfortable space; Kaitekina kukan wo sozosuru daikibo yukadanbo

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-01

    Floor heater radiates at a low temperature from under, warming people from the feet upward and filling the chamber with warm air mildly and uniformly. Keeping one`s head cool and one`s feet warm is the key to one`s health, goes a Japanese adage. Not only residences but also school houses, welfare facilities, hospitals, retail shops, and offices have come to accept high-capability floor heating equipment. For Musashino Municipal Sakai Nursery School where infants play barefoot, a floor heater is the best choice. A floor heat creates an environment safe and healthy, ensuring sound sleep. It does not cause dust to rise because it does not produce air currents in the room, and does not pollute air or make noise because the heat source is installed outdoors. Tsunekiyo-no-Sato, which is a facility for senior citizens in general, serves chiefly as a special nursing home for the aged, and therefore is requested to be comfortable, safe, and clean. For the old people whose body temperature adjusting system has degraded in function, floor heaters are the best for warming because it does not involve abrupt temperature changes. The Hokkaido Branch of Asahi Breweries, Ltd., employs a floor warming system for its wine house to ensure proper storage, and the ambient temperature in winter is kept at 3degC or higher

  5. Creating New Spaces for Learning: Fostering Experiential and Service Learning, Journeys through the African American Past

    Directory of Open Access Journals (Sweden)

    Dolapo Adeniji-Neill

    2012-01-01

    Full Text Available Problem statement: Experiential education and service learning are interchangeable. They are defined as an approach to education that implicitly trusts the learner’s ability to learn through experience, rather than a movement for change that seeks to challenge mainstream education. While literature, research, communities and schools recognize the importnce of experiential education, controversies exit as to their efficacies in learning processes. Approach: Experiential education and service learning are complimentary to formal education. They create communities and enables learners to interact with the world beyond the classroom. It was upon such community building and the belief that students would gain useful knowledge that would be life fulfilling that the “Project Period” was built. It started in a small community of a 300-student 9-12 secondary school in a village in New Hampshire, United States. Results: The projects were designed to allow students to engage with community, foster curiosity, ignite critical thoughts and enable students to see the world in multi-faceted dimensions. Conclusion: Studies on experiential learning tend to focus on environmental education and outdoor programs. As indicated, experiential education can be a part of K-College curricula and can focus on the big philosophical question, such as “How do historical periods affect the past, the present and the future”?

  6. Impact on liquids : void collapse and jet formation

    NARCIS (Netherlands)

    Gekle, Stephan

    2009-01-01

    A spectacular example of free surface flow is the impact of a solid object on a liquid: At impact a “crown” splash is created and a surface cavity (void) emerges which immediately starts to collapse due to the hydrostatic pressure of the surrounding liquid. Eventually the cavity closes in a single

  7. Impact on liquids : void collapse and jet formation

    NARCIS (Netherlands)

    Gekle, Stephan

    2009-01-01

    A spectacular example of free surface flow is the impact of a solid object on a liquid: At impact a “crown” splash is created and a surface cavity (void) emerges which immediately starts to collapse due to the hydrostatic pressure of the surrounding liquid. Eventually the cavity closes in a single p

  8. Impact on liquids : void collapse and jet formation

    NARCIS (Netherlands)

    Gekle, Stephan

    2009-01-01

    A spectacular example of free surface flow is the impact of a solid object on a liquid: At impact a “crown” splash is created and a surface cavity (void) emerges which immediately starts to collapse due to the hydrostatic pressure of the surrounding liquid. Eventually the cavity closes in a single p

  9. Creating Welcoming Spaces for Lesbian, Gay, Bisexual, and Transgender (LGBT) Patients: An Evaluation of the Health Care Environment.

    Science.gov (United States)

    McClain, Zachary; Hawkins, Linda A; Yehia, Baligh R

    2016-01-01

    Health outcomes are affected by patient, provider, and environmental factors. Previous studies have evaluated patient-level factors; few focusing on environment. Safe clinical spaces are important for lesbian, gay, bisexual, and transgender (LGBT) communities. This study evaluates current models of LGBT health care delivery, identifies strengths and weaknesses, and makes recommendations for LGBT spaces. Models are divided into LGBT-specific and LGBT-embedded care delivery. Advantages to both models exist, and they provide LGBT patients different options of healthcare. Yet certain commonalities must be met: a clean and confidential system. Once met, LGBT-competent environments and providers can advocate for appropriate care for LGBT communities, creating environments where they would want to seek care.

  10. The Online Learning Environment: Creating a space for Mauritian women learners

    Directory of Open Access Journals (Sweden)

    Sushita Gokool-Ramdoo

    2005-11-01

    Full Text Available This paper examines how online distance education acts to democratize access to, and suit the ontologies of, Mauritian women who seek to empower themselves for development. Data from semi-structured interviews of 30 middle class couples are presented in this paper. Interviews and analyses are premised on a feminist perspective and conducted within the social relations analysis framework. The objective of this research was to understand what types of supportive environments (social spaces enable Mauritian women to engage in educational endeavours that promote their personal potentials and creativities which, in turn, advance democracy for all citizens of Mauritius. Husbands were also interviewed to provide ground for analysis and to decrease bias, which can be generated by women-only data. (1 Marriage/ family and (2 occupation, represent the ‘social spaces’ selected for this study. Discretion, degree of learner control, and the outreach capacity inherent in distance learning makes the online modality a natural choice to democratize women’s access to education. Based on interviewees’ experiences and perceptions, this study concludes that online learning can enhance and democratize women’s access to education for personal development – but only if the power relationships in the two ‘social spaces’ are well understood and well negotiated by these women. The findings in this paper shed light on the importance of understanding ‘learner spaces’ when establishing and setting-up open learning organisations.

  11. "Compu-Void II": the computerized voiding diary.

    Science.gov (United States)

    Rabin, J M; McNett, J; Badlani, G H

    1996-02-01

    We have previously described an electronic voiding diary, "Compu-Void" (Copyright, 1990) developed to automate recording of bladder symptoms (Rabin et al., 1993). Our objectives in this, the second phase of this study, were to examine a group of subject and control patients' preference and compliance with regard to the "Compu-Void" (CV) compared to the standard written voiding diary (WD), to compare the two methods with respect to the amount and type of information obtained and to determine whether or not the order of use of each recording method influenced results in the subject group. Thirty-six women between the ages of 20 and 84 with bladder symptomatology were compared to a group 36 age-matched women. In 100% of subjects and 95% of control patients, CV entries exceeded the number made with the WD in voiding events and in subjects, in incontinent episodes recorded (P < 0.0005 and P < 0.005, respectively). Over 98% of subjects and over 80% of control patients preferred CV over the WD (p < 0.0005). The order of use of each recording method in subjects made no significant difference with regard to the volume of information obtained (p < 0.407), number of urinary leakage events recorded (p < 0.494), and fluid intake patterns (p < 0.410). Patient impressions of, and compliance with each method were not affected by order of use. The only difference regarding order of use was that most subjects who used the CV first also found the WD to be tedious (61% vs 14%). Our results suggest increased volume of data and of patient compliance in reporting bladder symptoms and events using CV, and that order of use is not an important factor in determining patient impressions of the two methods. The majority of subject and control patients preferred CV over traditional methods. An updated version of the software and hardware is also included.

  12. Creating space for citizenship: The impact of group structure on validating the voices of people with dementia.

    Science.gov (United States)

    Wiersma, Elaine C; O'Connor, Deborah L; Loiselle, Lisa; Hickman, Kathy; Heibein, Bill; Hounam, Brenda; Mann, Jim

    2016-05-01

    Recently, there has been increasing attention given to finding ways to help people diagnosed with dementia 'live well' with their condition. Frequently however, the attention has been placed on the family care partner as the foundation for creating a context that supports the person with dementia to live well. A recent participatory action research (PAR) study highlighted the importance of beginning to challenge some of the assumptions around how best to include family, especially within a context of supporting citizenship. Three advisory groups consisting of 20 people with dementia, 13 care partners, and three service providers, were set up in three locations across Canada to help develop a self-management program for people with dementia. The hubs met monthly for up to two years. One of the topics that emerged as extremely important to consider in the structuring of the program revolved around whether or not these groups should be segregated to include only people with dementia. A thematic analysis of these ongoing discussions coalesced around four inter-related themes: creating safe spaces; maintaining voice and being heard; managing the balancing act; and the importance of solidarity Underpinning these discussions was the fifth theme, recognition that 'one size doesn't fit all'. Overall an important finding was that the presence of family care-partners could have unintended consequences in relation to creating the space for active citizenship to occur in small groups of people with dementia although it could also offer some opportunities. The involvement of care partners in groups with people with dementia is clearly one that is complex without an obvious answer and dependent on a variety of factors to inform a solution, which can and should be questioned and revisited.

  13. Coupling effects of void size and void shape on the growth of prolate ellipsoidal microvoid

    Institute of Scientific and Technical Information of China (English)

    Minsheng Huang; Zhenhuan Li; Cheng Wang

    2005-01-01

    The combined effects of void size and void shape on the void growth are studied by using the classical spectrum method. An infinite solid containing an isolated prolate spheroidal void is considered to depict the void shape effect and the Fleck-Hutchinson phenomenological strain gradient plasticity theory is employed to capture the size effects. It is found that the combined effects of void size and void shape are mainly controlled by the remote stress triaxiality. Based on this, a new size-dependent void growth model similar to the Rice-Tracey model is proposed and an important conclusion about the size-dependent void growth is drawn: the growth rate of the void with radius smaller than a critical radius rc may be ignored. It is interesting that rc is a material constant independent of the initial void shape and the remote stress triaxiality.

  14. Latin-American Regional Developments in Space Technology and International Cooperation - Columbian Space Policy: An Approach to Create a National Space Agency

    Science.gov (United States)

    Arenales-Vergara, Oscar A.

    2002-01-01

    Space exploration is a great human adventure: culturally, scientifically, technologically and industrially. Since the earliest of times, civilizations have been united in their awe of, and inspiration by, the cosmos, as testified in particularly by the peoples and cultures of the Central and South American continent in pre-Columbian times. Today, space systems have become an essential tool for the scientific disciplines related to the knowledge of the universe, including our own planet and its close or its remote environment. The main objective of this research is to explain the way in which Colombia, rich in myths and secular legends connecting mankind to the universe, must in the present tackle the issue of its development of space activities. The context in which it could be carried out is also described, along with a perspective of the current state of science and technology in the space sector on a global scale. Any modern nation is concerned with its independence, whether political, economic, or intellectual. That is why we support the concept of countries in the process of development becoming actively involved in the international space scene. Indeed, having limitations in industrial and technological exchange, we feel excluded today from key fields for our tomorrow. This research thus proposes to demonstrate how in a time that can be regarded as one of the most serious crises in its history, Colombia could, in an atmosphere free from fratricidal conflicts, exploit its space matter capabilities. We do not limit our focus to the scientific field, but also consider the social, economic and cultural aspects. The results of this research delineate how Colombia could start a new optimistic phase of its development, joining the international space programs within the framework of agreements among the regional governments in Latin America.

  15. Magnetic pattern at supergranulation scale: the Void Size Distribution

    CERN Document Server

    Berrilli, Francesco; Del Moro, Dario

    2014-01-01

    The large-scale magnetic pattern of the quiet sun is dominated by the magnetic network. This network, created by photospheric magnetic fields swept into convective downflows, delineates the boundaries of large scale cells of overturning plasma and exhibits voids in magnetic organization. Such voids include internetwork fields, a mixed-polarity sparse field that populate the inner part of network cells. To single out voids and to quantify their intrinsic pattern a fast circle packing based algorithm is applied to 511 SOHO/MDI high resolution magnetograms acquired during the outstanding solar activity minimum between 23 and 24 cycles. The computed Void Distribution Function shows a quasi-exponential decay behavior in the range 10-60 Mm. The lack of distinct flow scales in such a range corroborates the hypothesis of multi-scale motion flows at the solar surface. In addition to the quasi-exponential decay we have found that the voids reveal departure from a simple exponential decay around 35 Mm.

  16. Statistical geometry of lattice chain polymers with voids of defined shapes: Sampling with strong constraints

    Science.gov (United States)

    Lin, Ming; Chen, Rong; Liang, Jie

    2008-02-01

    Proteins contain many voids, which are unfilled spaces enclosed in the interior. A few of them have shapes compatible to ligands and substrates and are important for protein functions. An important general question is how the need for maintaining functional voids is influenced by, and affects other aspects of proteins structures and properties (e.g., protein folding stability, kinetic accessibility, and evolution selection pressure). In this paper, we examine in detail the effects of maintaining voids of different shapes and sizes using two-dimensional lattice models. We study the propensity for conformations to form a void of specific shape, which is related to the entropic cost of void maintenance. We also study the location that voids of a specific shape and size tend to form, and the influence of compactness on the formation of such voids. As enumeration is infeasible for long chain polymer, a key development in this work is the design of a novel sequential Monte Carlo strategy for generating large number of sample conformations under very constraining restrictions. Our method is validated by comparing results obtained from sampling and from enumeration for short polymer chains. We succeeded in accurate estimation of entropic cost of void maintenance, with and without an increasing number of restrictive conditions, such as loops forming the wall of void with fixed length, with additionally fixed starting position in the sequence. Additionally, we have identified the key structural properties of voids that are important in determining the entropic cost of void formation. We have further developed a parametric model to predict quantitatively void entropy. Our model is highly effective, and these results indicate that voids representing functional sites can be used as an improved model for studying the evolution of protein functions and how protein function relates to protein stability.

  17. Creating Space and Time

    DEFF Research Database (Denmark)

    Sandvik, Kjetil; Refslund Christensen, Dorthe

    (‘memories’) for their deceased loved ones and get personal, social support in their mourning processes through communication with other mourners, through mutual appreciation of each other’s postings and through emotional labor reflected on the individual sites. The main focus in this paper is how online...... and very young children) and suggest that the process of producing memories needs to be understood in the light of there having been very little actual time and life spend with the child (if any at all) and that this lack of time is met by narrative and performative strategies aiming at providing a common...... the spatial, materialized and medialized strategies for keeping the child socially alive within the social life of the family and point to the socio-cultural matrices of these practices: The extensive use of props such as pictures, written material (poems, letters) and – on the graves (along with e...

  18. Size-Effects in Void Growth

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2005-01-01

    The size-effect on ductile void growth in metals is investigated. The analysis is based on unit cell models both of arrays of cylindrical voids under plane strain deformation, as well as arrays of spherical voids using an axisymmetric model. A recent finite strain generalization of two higher order...

  19. Hoverfly preference for high honeydew amounts creates enemy-free space for aphids colonizing novel host plants.

    Science.gov (United States)

    Vosteen, Ilka; Gershenzon, Jonathan; Kunert, Grit

    2016-09-01

    The existence of an enemy-free space can play an important role in aphid host race formation processes, but little is known about the mechanisms that create an area of low predation pressure on particular host plants. In this paper, we identify a mechanism generating lower predation pressure that promotes the maintenance of the different host races of the pea aphid (Acyrthosiphon pisum) complex, a well-studied model for ecological speciation. The pea aphid consists of at least 15 genetically distinct host races which are native to specific host plants of the legume family, but can all develop on the universal host plant Vicia faba. Previous work showed that hoverfly (Episyrphus balteatus) oviposition preferences contribute to the enemy-free space that helps to maintain the different pea aphid host races, and that higher amounts of honeydew are more attractive to ovipositing hoverflies. Here we demonstrated that aphid honeydew is produced in large amounts when aphid reproduction rate was highest, and is an important oviposition cue for hoverflies under field conditions. However, on less suitable host plants, where honeydew production is reduced, pea aphids enjoy lower predation rates. A reduction in enemy pressure can mitigate the performance disadvantages of aphids colonizing a novel host and probably plays an important role in pea aphid host race formation.

  20. 3D Property Modeling of Void Ratio by Cokriging

    Institute of Scientific and Technical Information of China (English)

    Yao Lingqing; Pan Mao; Cheng Qiuming

    2008-01-01

    Void ratio measures compactness of ground soil in geotechnical engineering. When samples are collected in certain area for mapping void ratios, other relevant types of properties such as water content may be also analyzed. To map the spatial distribution of void ratio in the area based on these types of point, observation data interpolation is often needed. Owing to the variance of sampling density along the horizontal and vertical directions, special consideration is required to handle anisotropy of estimator. 3D property modeling aims at predicting the overall distribution of property values from limited samples, and geostatistical method can he employed naturally here because they help to minimize the mean square error of estimation. To construct 3D property model of void ratio, cokriging was used considering its mutual correlation with water content, which is another important soil parameter. Moreover, K-D tree was adopted to organize the samples to accelerate neighbor query in 3D space during the above modeling process. At last, spatial configuration of void ratio distribution in an engineering body was modeled through 3D visualization, which provides important information for civil engineering purpose.

  1. Electromigration of intergranular voids in metal films for microelectronic interconnects

    CERN Document Server

    Averbuch, A; Ravve, I

    2003-01-01

    Voids and cracks often occur in the interconnect lines of microelectronic devices. They increase the resistance of the circuits and may even lead to a fatal failure. Voids may occur inside a single grain, but often they appear on the boundary between two grains. In this work, we model and analyze numerically the migration and evolution of an intergranular void subjected to surface diffusion forces and external voltage applied to the interconnect. The grain-void interface is considered one-dimensional, and the physical formulation of the electromigration and diffusion model results in two coupled fourth-order one-dimensional time-dependent PDEs. The boundary conditions are specified at the triple points, which are common to both neighboring grains and the void. The solution of these equations uses a finite difference scheme in space and a Runge-Kutta integration scheme in time, and is also coupled to the solution of a static Laplace equation describing the voltage distribution throughout the grain. Since the v...

  2. Sodium voiding analysis in Kalimer

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Won-Pyo; Jeong, Kwan-Seong; Hahn, Dohee [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    2001-07-01

    A sodium boiling model has been developed for calculations of the void reactivity feedback as well as the fuel and cladding temperatures in the KALIMER core after onset of sodium boiling. The sodium boiling in liquid metal reactors using sodium as coolant should be modeled because of phenomenon difference observed from that in light water reactor systems. The developed model is a multiple -bubble slug ejection model. It allows a finite number of bubbles in a channel at any time. Voiding is assumed to result from formation of bubbles that fill the whole cross section of the coolant channel except for liquid film left on the cladding surface. The vapor pressure, currently, is assumed to be uniform within a bubble. The present study is focused on not only demonstration of the sodium voiding behavior predicted by the developed model, but also confirmation on qualitative acceptance for the model. In results, the model catches important phenomena for sodium boiling, while further effort should be made for the complete analysis. (author)

  3. The life and death of cosmic voids

    CERN Document Server

    Sutter, P M; Falck, Bridget; Onions, Julian; Hamaus, Nico; Knebe, Alexander; Srisawat, Chaichalit; Schneider, Aurel

    2014-01-01

    We investigate the formation, growth, merger history, movement, and destruction of cosmic voids detected via the watershed transform in a cosmological N-body dark matter {\\Lambda}CDM simulation. By adapting a method used to construct halo merger trees, we are able to trace individual voids back to their initial appearance and record the merging and evolution of their progenitors at high redshift. For the scales of void sizes captured in our simulation, we find that the void formation rate peaks at scale factor 0.3, which coincides with a growth in the void hierarchy and the emergence of dark energy. Voids of all sizes appear at all scale factors, though the median initial void size decreases with time. When voids become detectable they have nearly their present-day volumes. Almost all voids have relatively stable growth rates and suffer only infrequent minor mergers. Dissolution of a void via merging is very rare. Instead, most voids maintain their distinct identity as annexed subvoids of a larger parent. The...

  4. Size-Effects in Void Growth

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2005-01-01

    The size-effect on ductile void growth in metals is investigated. The analysis is based on unit cell models both of arrays of cylindrical voids under plane strain deformation, as well as arrays of spherical voids using an axisymmetric model. A recent finite strain generalization of two higher order...... strain gradient plasticity models is implemented in a finite element program, which is used to study void growth numerically. The results based on the two models are compared. It is shown how gradient effects suppress void growth on the micron scale when compared to predictions based on conventional...... models. This increased resistance to void growth, due to gradient hardening, is accompanied by an increase in the overall strength for the material. Furthermore, for increasing initial void volume fraction, it is shown that the effect of gradients becomes more important to the overall response but less...

  5. The star formation activity in cosmic voids

    CERN Document Server

    Ricciardelli, Elena; Varela, Jesus; Quilis, Vicent

    2014-01-01

    Using a sample of cosmic voids identified in the Sloan Digital Sky Survey Data Release 7, we study the star formation activity of void galaxies. The properties of galaxies living in voids are compared with those of galaxies living in the void shells and with a control sample, representing the general galaxy population. Void galaxies appear to form stars more efficiently than shell galaxies and the control sample. This result can not be interpreted as a consequence of the bias towards low masses in underdense regions, as void galaxy subsamples with the same mass distribution as the control sample also show statistically different specific star formation rates. This highlights the fact that galaxy evolution in voids is slower with respect to the evolution of the general population. Nevertheless, when only the star forming galaxies are considered, we find that the star formation rate is insensitive to the environment, as the main sequence is remarkably constant in the three samples under consideration. This fact...

  6. Systemic atherosclerosis and voiding symptom.

    Science.gov (United States)

    Yeniel, A Ozgur; Ergenoglu, A Mete; Meseri, Reci; Ari, Anıl; Sancar, Ceren; Itil, Ismail Mete

    2017-03-01

    To evaluate the effect of atherosclerosis on the storage and voiding symptoms of the bladder in women with overactive bladder (OAB). We retrospectively reviewed the charts of women with OAB who were evaluated between 2013 and 2015 in our urogynecology unit. Charts were assessed for history, examination findings, urinary diary, quality of life (QOL) questionnaires, urodynamic studies (UDSs), and four main risk factors for atherosclerosis: hypertension, diabetes mellitus, smoking, and hyperlipidemia. In a previous study, these were defined as vascular risk factors. Cases were excluded for insufficient data, diabetes mellitus with dysregulated blood glucose, or prolapse greater than 1cm to avoid confusing bladder outlet obstruction. We included 167 eligible cases in this study. We evaluated storage and voiding symptoms such as frequency, nocturia, residual urine volume, and voiding difficulties and UDS findings such as maximum bladder capacity, first desire, strong desire, detrusor overactivity, and bladder contractility index. The vascular risk score was categorized as "no risk" if the woman did not have any of the four risk factors and "at risk" if she had any of the factors. Independent sample t-test and chi-square tests were performed for analyses. Among the participants (n=167), 71.9% had at least one vascular risk factor. Those who were at risk were facing significantly more wet-type OAB (p=0.003) and nocturia (p=0.023). Moreover, mean age (p=0.008) and mean gravidity (p=0.020) were significantly higher in the at-risk group, whereas mean total nocturia QOL questionnaire scores (p=0.029) were significantly lower. Our findings suggest that aging and atherosclerosis may be associated with severe OAB and poorer QOL. Nocturia and related parameters of poor quality can be explained by impaired bladder neck perfusion. Future trials need to assess vascular and molecular changes in women with OAB. Copyright © 2017 Elsevier B.V. All rights reserved.

  7. Nocturia: The circadian voiding disorder

    Directory of Open Access Journals (Sweden)

    Jin Wook Kim

    2016-05-01

    Full Text Available Nocturia is a prevalent condition of waking to void during the night. The concept of nocturia has evolved from being a symptomatic aspect of disease associated with the prostate or bladder to a form of lower urinary tract disorder. However, recent advances in circadian biology and sleep science suggest that it might be important to consider nocturia as a form of circadian dysfunction. In the current review, nocturia is reexamined with an introduction to sleep disorders and recent findings in circadian biology in an attempt to highlight the importance of rediscovering nocturia as a problem of chronobiology.

  8. Large-scale clustering of cosmic voids

    Science.gov (United States)

    Chan, Kwan Chuen; Hamaus, Nico; Desjacques, Vincent

    2014-11-01

    We study the clustering of voids using N -body simulations and simple theoretical models. The excursion-set formalism describes fairly well the abundance of voids identified with the watershed algorithm, although the void formation threshold required is quite different from the spherical collapse value. The void cross bias bc is measured and its large-scale value is found to be consistent with the peak background split results. A simple fitting formula for bc is found. We model the void auto-power spectrum taking into account the void biasing and exclusion effect. A good fit to the simulation data is obtained for voids with radii ≳30 Mpc h-1 , especially when the void biasing model is extended to 1-loop order. However, the best-fit bias parameters do not agree well with the peak-background results. Being able to fit the void auto-power spectrum is particularly important not only because it is the direct observable in galaxy surveys, but also our method enables us to treat the bias parameters as nuisance parameters, which are sensitive to the techniques used to identify voids.

  9. The dark matter of galaxy voids

    CERN Document Server

    Sutter, P M; Wandelt, Benjamin D; Weinberg, David H; Warren, Michael S

    2013-01-01

    How do observed voids relate to the underlying dark matter distribution? To examine the spatial distribution of dark matter contained within voids identified in galaxy surveys, we apply Halo Occupation Distribution models representing sparsely and densely sampled galaxy surveys to a high-resolution N-body simulation. We compare these galaxy voids to voids found in the halo distribution, low-resolution dark matter, and high-resolution dark matter. We find that voids at all scales in densely sampled surveys - and medium- to large-scale voids in sparse surveys - trace the same underdensities as dark matter, but they are larger in radius by ~20%, they have somewhat shallower density profiles, and they have centers offset by ~0.4Rv rms. However, in void-to-void comparison we find that shape estimators are less robust to sampling, and the largest voids in sparsely sampled surveys suffer fragmentation at their edges. We find that voids in galaxy surveys always correspond to underdensities in the dark matter, though ...

  10. The dark matter of galaxy voids

    Science.gov (United States)

    Sutter, P. M.; Lavaux, Guilhem; Wandelt, Benjamin D.; Weinberg, David H.; Warren, Michael S.

    2014-03-01

    How do observed voids relate to the underlying dark matter distribution? To examine the spatial distribution of dark matter contained within voids identified in galaxy surveys, we apply Halo Occupation Distribution models representing sparsely and densely sampled galaxy surveys to a high-resolution N-body simulation. We compare these galaxy voids to voids found in the halo distribution, low-resolution dark matter and high-resolution dark matter. We find that voids at all scales in densely sampled surveys - and medium- to large-scale voids in sparse surveys - trace the same underdensities as dark matter, but they are larger in radius by ˜20 per cent, they have somewhat shallower density profiles and they have centres offset by ˜ 0.4Rv rms. However, in void-to-void comparison we find that shape estimators are less robust to sampling, and the largest voids in sparsely sampled surveys suffer fragmentation at their edges. We find that voids in galaxy surveys always correspond to underdensities in the dark matter, though the centres may be offset. When this offset is taken into account, we recover almost identical radial density profiles between galaxies and dark matter. All mock catalogues used in this work are available at http://www.cosmicvoids.net.

  11. THE MANIFESTO ON EUROPEAN CRIMINAL PROCEDURE LAW – FOUNDATION FOR CREATING A COMMON SPACE OF EUROPEAN CRIMINAL JUSTICE

    Directory of Open Access Journals (Sweden)

    Rodica PANAINTE

    2015-09-01

    Full Text Available In this article, we propose to analyze the content of the Manifesto on European Criminal Procedure Law of 2013, and how this document can represent a foundation for the legal cooperation of the European states, and also for creating a unique, common space of European criminal justice. Elaborated by the European Criminal Policy Initiative and launched on November 2013, the Manifesto on European Criminal Procedure Law contains the principles and the rules that should be followed by the European penal legislator when gives shape to the laws in the field of Criminal Procedure. This document represents a natural following of the first Manifesto, in the field of substantive criminal law of 2009. The Manifesto concerns mainly the rules and the principles of criminal procedure because, as its authors affirm, this kind of rules have increasingly been shaped lately in European regulations, and also because the regulations in this field must reflect and respect the highest standards of the rule of law, as they must continuously and without exception guarantee the fundamental rights. In this study, we propose to focus upon the legal solutions found out by the authors of the Manifesto in order to attain, during the criminal proceedings, an equilibrium between the interest of the state and even of the Union to realize an effective criminal proceedings, and the individual human rights that are affected, and also an equilibrium between the actual legal order and the traditions of the member states.

  12. Self(ie-esteem? – A manifestation of adolescent self-creating endeavours in the virtual space of Facebook

    Directory of Open Access Journals (Sweden)

    Lili Fejes-Vékássy

    2017-09-01

    Full Text Available In the centre of our interest stand the manifestations of adolescent self-creating endeavours in the virtual space of the social media portal called Facebook. Frequent self-photography (selfie making, as a pronounced cultural feature of contemporary youth, and regular activity on Facebook handled as tightly connected factors; we propose that youngsters, bearing these attributes, have a different self-esteem than those adolescents who rarely or never take any photographs of themselves. In the first, quantitative part of our research the participants (N=80 filled in the Rosenberg Self-Esteem Scale and a questionnaire containing questions in connection with Facebook-usage (compiled by us. In the qualitative part of the research the participants took part in a half-structured interview, containing questions in connection with selfie­-making (also compiled by us. Our hypothesis was not proven by the statistical analysis, no connection could be testified between frequent selfie-making and low self-esteem.

  13. Universal density profile for cosmic voids.

    Science.gov (United States)

    Hamaus, Nico; Sutter, P M; Wandelt, Benjamin D

    2014-06-27

    We present a simple empirical function for the average density profile of cosmic voids, identified via the watershed technique in ΛCDM N-body simulations. This function is universal across void size and redshift, accurately describing a large radial range of scales around void centers with only two free parameters. In analogy to halo density profiles, these parameters describe the scale radius and the central density of voids. While we initially start with a more general four-parameter model, we find two of its parameters to be redundant, as they follow linear trends with the scale radius in two distinct regimes of the void sample, separated by its compensation scale. Assuming linear theory, we derive an analytic formula for the velocity profile of voids and find an excellent agreement with the numerical data as well. In our companion paper [Sutter et al., arXiv:1309.5087 [Mon. Not. R. Astron. Soc. (to be published)

  14. Void Profile from Planck Lensing Potential Map

    Science.gov (United States)

    Chantavat, Teeraparb; Sawangwit, Utane; Wandelt, Benjamin D.

    2017-02-01

    We use the lensing potential map from Planck CMB lensing reconstruction analysis and the “Public Cosmic Void Catalog” to measure the stacked void lensing potential. We have made an attempt to fit the HSW void profile parameters from the stacked lensing potential. In this profile, four parameters are needed to describe the shape of voids with different characteristic radii R V . However, we have found that after reducing the background noise by subtracting the average background, there is a residue lensing power left in the data. The inclusion of the environment shifting parameter, {γ }V, is necessary to get a better fit to the data with the residue lensing power. We divide the voids into two redshift bins: cmass1 (0.45Digital Sky Survey voids reside in an underdense region.

  15. Cosmology with void-galaxy correlations.

    Science.gov (United States)

    Hamaus, Nico; Wandelt, Benjamin D; Sutter, P M; Lavaux, Guilhem; Warren, Michael S

    2014-01-31

    Galaxy bias, the unknown relationship between the clustering of galaxies and the underlying dark matter density field is a major hurdle for cosmological inference from large-scale structure. While traditional analyses focus on the absolute clustering amplitude of high-density regions mapped out by galaxy surveys, we propose a relative measurement that compares those to the underdense regions, cosmic voids. On the basis of realistic mock catalogs we demonstrate that cross correlating galaxies and voids opens up the possibility to calibrate galaxy bias and to define a static ruler thanks to the observable geometric nature of voids. We illustrate how the clustering of voids is related to mass compensation and show that volume-exclusion significantly reduces the degree of stochasticity in their spatial distribution. Extracting the spherically averaged distribution of galaxies inside voids from their cross correlations reveals a remarkable concordance with the mass-density profile of voids.

  16. Voids in cosmological simulations over cosmic time

    Science.gov (United States)

    Wojtak, Radosław; Powell, Devon; Abel, Tom

    2016-06-01

    We study evolution of voids in cosmological simulations using a new method for tracing voids over cosmic time. The method is based on tracking watershed basins (contiguous regions around density minima) of well-developed voids at low redshift, on a regular grid of density field. It enables us to construct a robust and continuous mapping between voids at different redshifts, from initial conditions to the present time. We discuss how the new approach eliminates strong spurious effects of numerical origin when voids' evolution is traced by matching voids between successive snapshots (by analogy to halo merger trees). We apply the new method to a cosmological simulation of a standard Λ-cold-dark-matter cosmological model and study evolution of basic properties of typical voids (with effective radii 6 h-1 Mpc < Rv < 20 h-1 Mpc at redshift z = 0) such as volumes, shapes, matter density distributions and relative alignments. The final voids at low redshifts appear to retain a significant part of the configuration acquired in initial conditions. Shapes of voids evolve in a collective way which barely modifies the overall distribution of the axial ratios. The evolution appears to have a weak impact on mutual alignments of voids implying that the present state is in large part set up by the primordial density field. We present evolution of dark matter density profiles computed on isodensity surfaces which comply with the actual shapes of voids. Unlike spherical density profiles, this approach enables us to demonstrate development of theoretically predicted bucket-like shape of the final density profiles indicating a wide flat core and a sharp transition to high-density void walls.

  17. Additional circular intercostal space created by bifurcation of the left 3rd rib and its costal cartilage: a case report.

    Science.gov (United States)

    Kumar, Naveen; Guru, Anitha; Patil, Jyothsna; Ravindra, Swamy; Badagabettu, Satheesha Nayak

    2013-01-08

    In the thorax there are normally 11 pairs of intercostal spaces: the spaces between adjacent ribs. The intercostal spaces contain intercostal muscles, intercostal nerves and vessels. During a routine dissection for undergraduate medical students, we observed a variation involving the left 3rd rib and 3rd costal cartilage in the cadaver of a man of Indian ethnicity aged about 65 years. The left 3rd rib and its costal cartilage were bifurcated at their costochondral junction enclosing a small circular additional intercostal space. Muscle tissue covered by deep fascia was present in this circular intercostal space. The muscle in the circular intercostal space received its nerve supply from a branch of the 2nd intercostal nerve. Knowledge of such variations is helpful to surgeons operating on the anterior thoracic wall involving ribs and intercostal spaces. Knowing the possibility of the presence of an additional space between normal intercostal spaces can guide a surgeon through to a successful surgery.

  18. Novel thick-foam ferroelectret with engineered voids for energy harvesting applications

    Science.gov (United States)

    Luo, Z.; Shi, J.; Beeby, S. P.

    2016-11-01

    This work reports a novel thick-foam ferroelectret which is designed and engineered for energy harvesting applications. We fabricated this ferroelectret foam by mixing a chemical blowing agent with a polymer solution, then used heat treatment to activate the agent and create voids in the polymer foam. The dimensions of the foam, the density and size of voids can be well controlled in the fabrication process. Therefore, this ferroelectret can be engineered into optimized structure for energy harvesting applications.

  19. Size effects on void growth in single crystals with distributed voids

    DEFF Research Database (Denmark)

    Borg, Ulrik; Niordson, Christian Frithiof; Kysar, J.W.

    2008-01-01

    The effect of void size on void growth in single crystals with uniformly distributed cylindrical voids is studied numerically using a finite deformation strain gradient crystal plasticity theory with an intrinsic length parameter. A plane strain cell model is analyzed for a single crystal...

  20. The darkness that shaped the void: dark energy and cosmic voids

    NARCIS (Netherlands)

    Bos, E. G. Patrick; van de Weygaert, Rien; Dolag, Klaus; Pettorino, Valeria

    2012-01-01

    We assess the sensitivity of void shapes to the nature of dark energy that was pointed out in recent studies and also investigate whether or not void shapes are useable as an observational probe in galaxy redshift surveys. Our focus is on the evolution of the mean void ellipticity and its underlying

  1. The darkness that shaped the void : Dark energy and cosmic voids

    NARCIS (Netherlands)

    Bos, E. G. Patrick; van de Weygaert, Rien; Dolag, Klaus; Pettorino, Valeria

    2012-01-01

    We assess the sensitivity of void shapes to the nature of dark energy that was pointed out in recent studies and also investigate whether or not void shapes are useable as an observational probe in galaxy redshift surveys. Our focus is on the evolution of the mean void ellipticity and its underlying

  2. Voids in cosmological simulations over cosmic time

    CERN Document Server

    Wojtak, Radosław; Abel, Tom

    2016-01-01

    We study evolution of voids in cosmological simulations using a new method for tracing voids over cosmic time. The method is based on tracking watershed basins (contiguous regions around density minima) of well developed voids at low redshift, on a regular grid of density field. It enables us to construct a robust and continuous mapping between voids at different redshifts, from initial conditions to the present time. We discuss how the new approach eliminates strong spurious effects of numerical origin when voids evolution is traced by matching voids between successive snapshots (by analogy to halo merger trees). We apply the new method to a cosmological simulation of a standard LambdaCDM cosmological model and study evolution of basic properties of typical voids (with effective radii between 6Mpc/h and 20Mpc/h at redshift z=0) such as volumes, shapes, matter density distributions and relative alignments. The final voids at low redshifts appear to retain a significant part of the configuration acquired in in...

  3. Tracing the gravitational potential using cosmic voids

    CERN Document Server

    Nadathur, Seshadri; Crittenden, Robert

    2016-01-01

    The properties of large underdensities in the distribution of galaxies in the Universe, known as cosmic voids, are potentially sensitive probes of fundamental physics. We use data from the MultiDark suite of N-body simulations and multiple halo occupation distribution mocks to study the relationship between galaxy voids and the gravitational potential $\\Phi$. We find that the majority of galaxy voids correspond to local density minima in larger-scale overdensities, and thus lie in potential wells. However, a subset of voids can be identified that closely trace maxima of the gravitational potential and thus stationary points of the velocity field. We identify a new void observable, $\\lambda_v$, which depends on a combination of the void size and the average galaxy density contrast within the void, and show that it provides a good proxy indicator of the potential at the void location. A simple linear scaling of $\\Phi$ as a function of $\\lambda_v$ is found to hold, independent of the redshift and properties of t...

  4. Simulation of dust voids in complex plasmas

    NARCIS (Netherlands)

    W. J. Goedheer,; Land, V.

    2008-01-01

    In dusty radio-frequency (RF) discharges under micro-gravity conditions often a void is observed, a dust free region in the discharge center. This void is generated by the drag of the positive ions pulled out of the discharge by the electric field. We have developed a hydrodynamic model for dusty RF

  5. Assembly of filamentary void galaxy configurations

    NARCIS (Netherlands)

    Rieder, Steven; van de Weijgaert, Rien; Cautun, Marius; Beygu, Burcu; Zwart, Simon Portegies

    2013-01-01

    We study the formation and evolution of filamentary configurations of dark matter haloes in voids. Our investigation uses the high-resolution Lambda cold dark matter simulation CosmoGrid to look for void systems resembling the VGS_31 elongated system of three interacting galaxies that was recently

  6. The Hierarchical Structure and Dynamics of Voids

    CERN Document Server

    Aragon-Calvo, M A

    2012-01-01

    Contrary to the common view voids have very complex internal structure and dynamics. Here we show how the hierarchy of structures in the density field inside voids is reflected by a similar hierarchy of structures in the velocity field. Voids defined by dense filaments and clusters can de described as simple expanding domains with coherent flows everywhere except at their boundaries. At scales smaller that the void radius the velocity field breaks into expanding sub-domains corresponding to sub- voids. These sub-domains break into even smaller sub-sub domains at smaller scales resulting in a nesting hierarchy of locally expanding domains. The ratio between the magnitude of the velocity field responsible for the expansion of the void and the velocity field defining the sub voids is approximately one order of magnitude. The small-scale components of the velocity field play a minor role in the shaping of the voids but they define the local dynamics directly affecting the processes of galaxy formation and evoluti...

  7. In search of empty places: Voids in the distribution of galaxies

    Science.gov (United States)

    Bucklein, Brian K.

    2010-12-01

    We investigate several techniques to identify voids in the galaxy distribution of matter in the universe. We utilize galaxy number counts as a function of apparent magnitude and Wolf plots to search a two- or three-dimensional data set in a pencil-beam fashion to locate voids within the field of view. The technique is able to distinguish between voids that represent simply a decrease in density as well as those that show a build up of galaxies on the front or back side of the void. This method turns out to be primarily useable only at relatively short range (out to about 200 Mpc). Beyond this distance, the characteristics indicating a void become increasingly difficult to separate from the statistical background noise. We apply the technique to a very simplified model as well as to the Millennium Run dark matter simulation. We then compare results with those obtained on the Sloan Digital Sky Survey. We also created the Watershed Void Examiner (WaVE) which treats densities in a fashion similar to elevation on a topographical map, and then we allow the "terrain" to flood. The flooded low-lying regions are identified as voids, which are allowed to grow and merge as the level of flooding becomes higher (the overdensity threshold increases). Void statistics can be calculated for each void. We also determine that within the Millennium Run semi-analytic galaxy catalog, the walls that separate the voids are permeable at a scale of 4 Mpc. For each resolution that we tested, there existed a characteristic density at which the walls could be penetrated, allowing a single void to grow to dominate the volume. With WaVE, we are able to get comparable results to those previously published, but often with fewer choices of parameters that could bias the results. We are also able to determine the the density at which the number of voids peaks for different resolutions as well as the expected number of void galaxies. The number of void galaxies is amazingly consistent at an

  8. VIDE: The Void IDentification and Examination toolkit

    CERN Document Server

    Sutter, P M; Hamaus, Nico; Pisani, Alice; Wandelt, Benjamin D; Warren, Michael S; Villaescusa-Navarro, Francisco; Zivick, Paul; Mao, Qingqing; Thompson, Benjamin B

    2014-01-01

    We present VIDE, the Void IDentification and Examination toolkit, an open-source Python/C++ code for finding cosmic voids in galaxy redshift surveys and N-body simulations, characterizing their properties, and providing a platform for more detailed analysis. At its core, VIDE uses a greatly enhanced version of ZOBOV (Neyinck 2008) to calculate a Voronoi tessellation for estimating the density field and a watershed transform to construct voids. The watershed levels are used to place voids in a hierarchical tree. VIDE provides significant additional functionality for both pre- and post-processing: for example, VIDE can work with volume- or magnitude-limited galaxy samples with arbitrary survey geometries, or dark matter particles or halo catalogs in a variety of common formats. It can also randomly subsample inputs and includes a Halo Occupation Distribution model for constructing mock galaxy populations. VIDE outputs a summary of void properties in plain ASCII, and provides a Python API to perform many analysi...

  9. Blocking effect of twin boundaries on partial dislocation emission from void surfaces.

    Science.gov (United States)

    Zhang, Lifeng; Zhou, Haofei; Qu, Shaoxing

    2012-03-02

    Recent discovery that nanoscale twin boundaries can be introduced in ultrafine-grained metals to improve strength and ductility has renewed interest in the mechanical behavior and deformation mechanisms of these nanostructured materials. By controlling twin boundary spacing, the effect of twin boundaries on void growth is investigated by using atomistic simulation method. The strength is significantly enhanced due to the discontinuous slip system associated with these coherent interfaces. Atomic-scale mechanisms underlying void growth, as well as the interaction between twin boundaries and the void, are revealed in details.

  10. Study of localization in a void-sheet under stress states near pure shear

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2015-01-01

    to the principal tensile stress. A number of previous investigations have shown that such imperfections can lead to plastic flow localization in a shear band and subsequently lead to void-sheet fracture inside the band. The present analyses confirm that the imperfection results in localization failure, even......-cracks. For the largest imperfection considered, i.e. a relatively large ratio of the void radius to void spacing, there is still a range of stress states in the vicinity of pure shear, where no localization is predicted, and for smaller imperfections this range is larger....

  11. Creating standards: Creating illusions?

    DEFF Research Database (Denmark)

    Linneberg, Mai Skjøtt

    written standards may open up for the creation of illusions. These are created when written standards' content is not in accordance with the perception standard adopters and standard users have of the specific practice phenomenon's content. This general theoretical argument is exemplified by the specific...

  12. Additional circular intercostal space created by bifurcation of the left 3rd rib and its costal cartilage: a case report

    Directory of Open Access Journals (Sweden)

    Kumar Naveen

    2013-01-01

    Full Text Available Abstract Introduction In the thorax there are normally 11 pairs of intercostal spaces: the spaces between adjacent ribs. The intercostal spaces contain intercostal muscles, intercostal nerves and vessels. Case presentation During a routine dissection for undergraduate medical students, we observed a variation involving the left 3rd rib and 3rd costal cartilage in the cadaver of a man of Indian ethnicity aged about 65 years. The left 3rd rib and its costal cartilage were bifurcated at their costochondral junction enclosing a small circular additional intercostal space. Muscle tissue covered by deep fascia was present in this circular intercostal space. The muscle in the circular intercostal space received its nerve supply from a branch of the 2nd intercostal nerve. Conclusions Knowledge of such variations is helpful to surgeons operating on the anterior thoracic wall involving ribs and intercostal spaces. Knowing the possibility of the presence of an additional space between normal intercostal spaces can guide a surgeon through to a successful surgery.

  13. Cosmic voids and void lensing in the Dark Energy Survey Science Verification data

    Energy Technology Data Exchange (ETDEWEB)

    Sánchez, C.; Clampitt, J.; Kovacs, A.; Jain, B.; García-Bellido, J.; Nadathur, S.; Gruen, D.; Hamaus, N.; Huterer, D.; Vielzeuf, P.; Amara, A.; Bonnett, C.; DeRose, J.; Hartley, W. G.; Jarvis, M.; Lahav, O.; Miquel, R.; Rozo, E.; Rykoff, E. S.; Sheldon, E.; Wechsler, R. H.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Benoit-Lévy, A.; Bernstein, G. M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D' Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Neto, A. Fausti; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Krause, E.; Kuehn, K.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Melchior, P.; Plazas, A. A.; Reil, K.; Romer, A. K.; Sanchez, E.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Thomas, D.; Walker, A. R.; Weller, J.

    2016-10-26

    Galaxies and their dark matter halos populate a complicated filamentary network around large, nearly empty regions known as cosmic voids. Cosmic voids are usually identified in spectroscopic galaxy surveys, where 3D information about the large-scale structure of the Universe is available. Although an increasing amount of photometric data is being produced, its potential for void studies is limited since photometric redshifts induce line-of-sight position errors of $\\sim50$ Mpc/$h$ or more that can render many voids undetectable. In this paper we present a new void finder designed for photometric surveys, validate it using simulations, and apply it to the high-quality photo-$z$ redMaGiC galaxy sample of the Dark Energy Survey Science Verification (DES-SV) data. The algorithm works by projecting galaxies into 2D slices and finding voids in the smoothed 2D galaxy density field of the slice. Fixing the line-of-sight size of the slices to be at least twice the photo-$z$ scatter, the number of voids found in these projected slices of simulated spectroscopic and photometric galaxy catalogs is within 20% for all transverse void sizes, and indistinguishable for the largest voids of radius $\\sim 70$ Mpc/$h$ and larger. The positions, radii, and projected galaxy profiles of photometric voids also accurately match the spectroscopic void sample. Applying the algorithm to the DES-SV data in the redshift range $0.2voids with comoving radii spanning the range 18-120 Mpc/$h$, and carry out a stacked weak lensing measurement. With a significance of $4.4\\sigma$, the lensing measurement confirms the voids are truly underdense in the matter field and hence not a product of Poisson noise, tracer density effects or systematics in the data. It also demonstrates, for the first time in real data, the viability of void lensing studies in photometric surveys.

  14. "Smart" Spaces Aren't Just for Classrooms Anymore: Intentional Design Creates Casual Learning Opportunities on Today's Campuses

    Science.gov (United States)

    James, Darren L.; Infanzon, Nestor

    2010-01-01

    Each educational environment exhibits a distinct personality that supports and influences the student body. As educational institutions develop new spaces and buildings for university and college campuses nationwide, the need increasingly arises to provide spaces that both help fulfill each school's educational mission and reinforce the vitality…

  15. Modelling Void Abundance in Modified Gravity

    CERN Document Server

    Voivodic, Rodrigo; Llinares, Claudio; Mota, David F

    2016-01-01

    We use a spherical model and an extended excursion set formalism with drifting diffusive barriers to predict the abundance of cosmic voids in the context of general relativity as well as f(R) and symmetron models of modified gravity. We detect spherical voids from a suite of N-body simulations of these gravity theories and compare the measured void abundance to theory predictions. We find that our model correctly describes the abundance of both dark matter and galaxy voids, providing a better fit than previous proposals in the literature based on static barriers. We use the simulation abundance results to fit for the abundance model free parameters as a function of modified gravity parameters, and show that counts of dark matter voids can provide interesting constraints on modified gravity. For galaxy voids, more closely related to optical observations, we find that constraining modified gravity from void abundance alone may be significantly more challenging. In the context of current and upcoming galaxy surv...

  16. Dislocation creation and void nucleation in FCC ductile metals under tensile loading: a general microscopic picture.

    Science.gov (United States)

    Pang, Wei-Wei; Zhang, Ping; Zhang, Guang-Cai; Xu, Ai-Guo; Zhao, Xian-Geng

    2014-11-10

    Numerous theoretical and experimental efforts have been paid to describe and understand the dislocation and void nucleation processes that are fundamental for dynamic fracture modeling of strained metals. To date an essential physical picture on the self-organized atomic collective motions during dislocation creation, as well as the essential mechanisms for the void nucleation obscured by the extreme diversity in structural configurations around the void nucleation core, is still severely lacking in literature. Here, we depict the origin of dislocation creation and void nucleation during uniaxial high strain rate tensile processes in face-centered-cubic (FCC) ductile metals. We find that the dislocations are created through three distinguished stages: (i) Flattened octahedral structures (FOSs) are randomly activated by thermal fluctuations; (ii) The double-layer defect clusters are formed by self-organized stacking of FOSs on the close-packed plane; (iii) The stacking faults are formed and the Shockley partial dislocations are created from the double-layer defect clusters. Whereas, the void nucleation is shown to follow a two-stage description. We demonstrate that our findings on the origin of dislocation creation and void nucleation are universal for a variety of FCC ductile metals with low stacking fault energies.

  17. Voids' System in the Woven Composite Structure

    Institute of Scientific and Technical Information of China (English)

    Pavla VOZKOVA

    2006-01-01

    Composites are common material constructions for high-tech use now. Mechanical properties of woven reinforced composites are influenced by voids inside the structure.Voids could be classified to the two sections. Long and thin cracks are more dangerous than pores. It is important to find relations between preparation and place of occurrence of voids. This paper classifies defects according to rise mechanism, point of occurrence, orientation, size and affect to the properties. Image analysis was used for observing samples. Future work would be oriented not only to observing real samples, but also to calculate mechanical properties from real and ideal structures in 3D woven reinforced composites.

  18. Practical Statistics for the Voids Between Galaxies

    Directory of Open Access Journals (Sweden)

    Zaninetti, L.

    2010-12-01

    Full Text Available The voids between galaxies are identified withthe volumes of the Poisson Voronoi tessellation.Two new survival functions for the apparent radii of voids are derived. The sectional normalized area ofthe Poisson Voronoi tessellation is modelledby the Kiang function and by the exponential function. Two new survival functions with equivalent sectional radius are therefore derived; they represent an alternative to the survival function of voids between galaxies as given by the self-similar distribution. The spatial appearance of slices of the 2dF Galaxy Redshift Survey is simulated.

  19. The darkness that shaped the void: dark energy and cosmic voids

    CERN Document Server

    Bos, E G Patrick; Dolag, Klaus; Pettorino, Valeria

    2012-01-01

    Aims: We assess the sensitivity of void shapes to the nature of dark energy that was pointed out in recent studies. We investigate whether or not void shapes are useable as an observational probe in galaxy redshift surveys. We focus on the evolution of the mean void ellipticity and its underlying physical cause. Methods: We analyse the morphological properties of voids in five sets of cosmological N-body simulations, each with a different nature of dark energy. Comparing voids in the dark matter distribution to those in the halo population, we address the question of whether galaxy redshift surveys yield sufficiently accurate void morphologies. Voids are identified using the parameter free Watershed Void Finder. The effect of redshift distortions is investigated as well. Results: We confirm the statistically significant sensitivity of voids in the dark matter distribution. We identify the level of clustering as measured by \\sigma_8(z) as the main cause of differences in mean void shape . We find that in the h...

  20. Creating a marketing channels strategy for European market entry: a case study for eloSpaces Oy

    OpenAIRE

    Babanina, Daria

    2016-01-01

    This thesis is produced as a case study for eloSpaces, Finnish-Chinese startup company based in Espoo, Finland. eloSpaces develops a unique capsule for people to do the focus work and enjoy privacy. The home market for eloSpaces is China and their current aim is to enter also European market in the nearest future. Therefore, the main objective for thesis was to identify the shortest and most efficient market entry strategy for the full product launch in Europe with highest impact on profits. ...

  1. Cosmic voids and void lensing in the Dark Energy Survey Science Verification data

    Science.gov (United States)

    Sánchez, C.; Clampitt, J.; Kovacs, A.; Jain, B.; García-Bellido, J.; Nadathur, S.; Gruen, D.; Hamaus, N.; Huterer, D.; Vielzeuf, P.; Amara, A.; Bonnett, C.; DeRose, J.; Hartley, W. G.; Jarvis, M.; Lahav, O.; Miquel, R.; Rozo, E.; Rykoff, E. S.; Sheldon, E.; Wechsler, R. H.; Zuntz, J.; Abbott, T. M. C.; Abdalla, F. B.; Annis, J.; Benoit-Lévy, A.; Bernstein, G. M.; Bernstein, R. A.; Bertin, E.; Brooks, D.; Buckley-Geer, E.; Rosell, A. Carnero; Kind, M. Carrasco; Carretero, J.; Crocce, M.; Cunha, C. E.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Diehl, H. T.; Dietrich, J. P.; Doel, P.; Evrard, A. E.; Neto, A. Fausti; Flaugher, B.; Fosalba, P.; Frieman, J.; Gaztanaga, E.; Gruendl, R. A.; Gutierrez, G.; Honscheid, K.; James, D. J.; Krause, E.; Kuehn, K.; Lima, M.; Maia, M. A. G.; Marshall, J. L.; Melchior, P.; Plazas, A. A.; Reil, K.; Romer, A. K.; Sanchez, E.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Sobreira, F.; Suchyta, E.; Tarle, G.; Thomas, D.; Walker, A. R.; Weller, J.; DES Collaboration

    2017-02-01

    Cosmic voids are usually identified in spectroscopic galaxy surveys, where 3D information about the large-scale structure of the Universe is available. Although an increasing amount of photometric data is being produced, its potential for void studies is limited since photometric redshifts induce line-of-sight position errors of ≥50 Mpc h-1which can render many voids undetectable. We present a new void finder designed for photometric surveys, validate it using simulations, and apply it to the high-quality photo-z redMaGiC galaxy sample of the DES Science Verification data. The algorithm works by projecting galaxies into 2D slices and finding voids in the smoothed 2D galaxy density field of the slice. Fixing the line-of-sight size of the slices to be at least twice the photo-z scatter, the number of voids found in simulated spectroscopic and photometric galaxy catalogues is within 20 per cent for all transverse void sizes, and indistinguishable for the largest voids (Rv ≥ 70 Mpc h-1). The positions, radii, and projected galaxy profiles of photometric voids also accurately match the spectroscopic void sample. Applying the algorithm to the DES-SV data in the redshift range 0.2 < z < 0.8, we identify 87 voids with comoving radii spanning the range 18-120 Mpc h-1, and carry out a stacked weak lensing measurement. With a significance of 4.4σ, the lensing measurement confirms that the voids are truly underdense in the matter field and hence not a product of Poisson noise, tracer density effects or systematics in the data. It also demonstrates, for the first time in real data, the viability of void lensing studies in photometric surveys.

  2. DIVE in the cosmic web: voids with Delaunay triangulation from discrete matter tracer distributions

    Science.gov (United States)

    Zhao, Cheng; Tao, Charling; Liang, Yu; Kitaura, Francisco-Shu; Chuang, Chia-Hsun

    2016-07-01

    We present a novel parameter-free cosmological void finder (DIVE, Delaunay TrIangulation Void findEr) based on Delaunay Triangulation (DT), which efficiently computes the empty spheres constrained by a discrete set of tracers. We define the spheres as DT voids, and describe their properties, including a universal density profile together with an intrinsic scatter. We apply this technique on 100 halo catalogues with volumes of 2.5 h-1Gpc side each, with a bias and number density similar to the Baryon Oscillation Spectroscopic Survey CMASS luminous red galaxies, performed with the PATCHY code. Our results show that there are two main species of DT voids, which can be characterized by the radius: they have different responses to halo redshift space distortions, to number density of tracers, and reside in different dark matter environments. Based on dynamical arguments using the tidal field tensor, we demonstrate that large DT voids are hosted in expanding regions, whereas the haloes used to construct them reside in collapsing ones. Our approach is therefore able to efficiently determine the troughs of the density field from galaxy surveys, and can be used to study their clustering. We further study the power spectra of DT voids, and find that the bias of the two populations are different, demonstrating that the small DT voids are essentially tracers of groups of haloes.

  3. Central African Republic Public Expenditure Review : Creating Fiscal Space to Transition Out of Fragility Through Growth and Poverty Reduction

    OpenAIRE

    World Bank

    2012-01-01

    This public expenditure review (PER) aims to assist the government in its efforts to achieve a transition out of fragility through growth and development. Higher and sustained per capita real gross domestic product (GDP) growth to raise the income of the population and create employment is needed to reduce poverty and lower the risk of reversion to conflict. Significant productive investme...

  4. Cosmic Voids in the SDSS DR12 BOSS Galaxy Sample: The Alcock-Paczynski Test

    Science.gov (United States)

    Mao, Qingqing; Berlind, Andreas A.; Scherrer, Robert J.; Neyrinck, Mark C.; Scoccimarro, Román; Tinker, Jeremy L.; McBride, Cameron K.; Schneider, Donald P.

    2017-02-01

    We apply the Alcock–Paczyński (AP) test to stacked voids identified using the final data release (DR12) of the Baryon Oscillation Spectroscopic Survey (BOSS). We also use 1000 mock galaxy catalogs that match the geometry, density, and clustering properties of the BOSS sample in order to characterize the statistical uncertainties of our measurements and take into account systematic errors such as redshift space distortions. For both BOSS data and mock catalogs, we use the ZOBOV algorithm to identify voids, we stack together all voids with effective radii of 30{--}100 {h}-1 {Mpc} in the redshift range of 0.43–0.7, and we accurately measure the shape of the stacked voids. Our tests with the mock catalogs show that we measure the stacked void ellipticity with a statistical precision of 2.6%. The stacked voids in redshift space are slightly squashed along the line of sight, consistent with previous studies. We repeat this measurement of stacked void shape in the BOSS data, assuming several values of {{{Ω }}}{{m}} within the flat {{Λ }}{CDM} model, and we compare this to the mock catalogs in redshift space to perform the AP test. We obtain a constraint of {{{Ω }}}{{m}}={0.38}-0.15+0.18 at the 68% confidence level from the AP test. We discuss the sources of statistical and systematic noise that affect the constraining power of this method. In particular, we find that the measured ellipticity of stacked voids changes more weakly with cosmology than the standard AP prediction, leading to significantly weaker constraints. We discuss how constraints will improve in future surveys with larger volumes and densities.

  5. Development of video-assisted breast cancer surgery: Initial experience with a novel method for creating working space without prior liposuction

    OpenAIRE

    Wu, Qian-Fu; Yu, Ying-Hua; Zhu, Xiao; Cui, Ying; Mo, Qin-Guo; WEI, CHANG-YUAN; Lin, Xue-Juan; Liu, Xue-Ying; Xie, Wei-Kang; Gan, Shui; Lei, Wei

    2017-01-01

    Endoscopic techniques are promising in breast surgery. In order to create working space, liposuction is widely used in video-assisted breast surgery (VABS). However, the use of liposuction is likely associated with side effects that may partly limit the application of VABS. Therefore, a new technique of endoscopic axillary lymphadenectomy without prior liposuction was developed by our group. A total of 106 female patients underwent VABS, with special adaptation of the video-assisted surgical ...

  6. Properties of Galaxies in and around Voids

    CERN Document Server

    Hopp, U

    1997-01-01

    Two surveys for intrinsically faint galaxies towards nearby voids have been conducted at the MPI für Astronomie, Heidelberg. One selected targets from a new diameter limited ($\\Phi \\ge 5''$) catalog with morphological criteria while the other used digitized objective prism Schmidt plates to select mainly HII dwarf galaxies. For some 450 galaxies, redshifts and other optical data were obtained. We studied the spatial distribution of the sample objects, their luminosity function, and their intrinsic properties. Most of the galaxies belong to already well known sheets and filaments. But we found about a dozen highly isolated galaxies in each sample (nearest neighborhood distance $\\ge 3 h_{75}^{-1} Mpc$). These tend to populate additional structures and are not distributed homogeneously throughout the voids. As our results on 'void galaxies' still suffer from small sample statistics, I also tried to combine similar existing surveys of nearby voids to get further hints on the larger structure and on the luminosit...

  7. Topology optimization with flexible void area

    DEFF Research Database (Denmark)

    Clausen, Anders; Aage, Niels; Sigmund, Ole

    2014-01-01

    This paper presents a methodology for including fixed-area flexible void domains into the minimum compliance topology optimization problem. As opposed to the standard passive elements approach of rigidly specifying void areas within the design domain, the suggested approach allows these areas...... to be flexibly reshaped and repositioned subject to penalization on their moments of inertia, the positions of their centers of mass, and their shapes. The flexible void areas are introduced through a second, discrete design variable field, using the same discretization as the standard field of continuous...... density variables. The formulation is based on a combined approach: The primary sub-problem is to minimize compliance, subject to a volume constraint, with a secondary sub-problem of minimizing the disturbance from the flexible void areas. The design update is performed iteratively between the two...

  8. Neutron Imaging Calibration to Measure Void Fraction

    Energy Technology Data Exchange (ETDEWEB)

    Geoghegan, Patrick J [ORNL; Bilheux, Hassina Z [ORNL; Sharma, Vishaldeep [ORNL; Fricke, Brian A [ORNL

    2015-01-01

    Void fraction is an intuitive parameter that describes the fraction of vapor in a two-phase flow. It appears as a key variable in most heat transfer and pressure drop correlations used to design evaporating and condensing heat exchangers, as well as determining charge inventory in refrigeration systems. Void fraction measurement is not straightforward, however, and assumptions on the invasiveness of the measuring technique must be made. Neutron radiography or neutron imaging has the potential to be a truly non-invasive void fraction measuring technique but has until recently only offered qualitative descriptions of two-phase flow, in terms of flow maldistributions, for example. This paper describes the calibration approach necessary to employ neutron imaging to measure steady-state void fraction. Experiments were conducted at the High Flux Isotope Reactor (HFIR) Cold Guide 1D neutron imaging facility at Oak Ridge National Laboratory (ORNL), Oak Ridge, TN, USA.

  9. Void growth in metals: Atomistic calculations

    Energy Technology Data Exchange (ETDEWEB)

    Traiviratana, Sirirat [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); Bringa, Eduardo M. [Materials Science Department, Lawrence Livermore National Laboratory, Livermore, CA 94550 (United States); Benson, David J. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); Meyers, Marc A. [Department of Mechanical and Aerospace Engineering, University of California, San Diego, La Jolla, CA 92093 (United States); NanoEngineering, University of California, San Diego, La Jolla, CA 92093 (United States)], E-mail: mameyers@ucsd.edu

    2008-09-15

    Molecular dynamics simulations in monocrystalline and bicrystalline copper were carried out with LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator) to reveal void growth mechanisms. The specimens were subjected to tensile uniaxial strains; the results confirm that the emission of (shear) loops is the primary mechanism of void growth. It is observed that many of these shear loops develop along two slip planes (and not one, as previously thought), in a heretofore unidentified mechanism of cooperative growth. The emission of dislocations from voids is the first stage, and their reaction and interaction is the second stage. These loops, forming initially on different {l_brace}1 1 1{r_brace} planes, join at the intersection, if the Burgers vector of the dislocations is parallel to the intersection of two {l_brace}1 1 1{r_brace} planes: a <1 1 0> direction. Thus, the two dislocations cancel at the intersection and a biplanar shear loop is formed. The expansion of the loops and their cross slip leads to the severely work-hardened region surrounding a growing void. Calculations were carried out on voids with different sizes, and a size dependence of the stress threshold to emit dislocations was obtained by MD, in disagreement with the Gurson model which is scale independent. This disagreement is most marked for the nanometer sized voids. The scale dependence of the stress required to grow voids is interpreted in terms of the decreasing availability of optimally oriented shear planes and increased stress required to nucleate shear loops as the void size is reduced. The growth of voids simulated by MD is compared with the Cocks-Ashby constitutive model and significant agreement is found. The density of geometrically necessary dislocations as a function of void size is calculated based on the emission of shear loops and their outward propagation. Calculations are also carried out for a void at the interface between two grains to simulate polycrystalline

  10. Zipf's law for fractal voids and a new void-finder

    CERN Document Server

    Gaite, J

    2005-01-01

    Voids are a prominent feature of fractal point distributions but there is no precise definition of what is a void (except in one dimension). Here we propose a definition of voids that uses methods of discrete stochastic geometry, in particular, Delaunay and Voronoi tessellations, and we construct a new algorithm to search for voids in a point set. We find and rank-order the voids of suitable examples of fractal point sets in one and two dimensions to test whether Zipf's power-law holds. We conclude affirmatively and, furthermore, that the rank-ordering of voids conveys similar information to the number-radius function, as regards the scaling regime and the transition to homogeneity. So it is an alternative tool in the analysis of fractal point distributions with crossover to homogeneity and, in particular, of the distribution of galaxies.

  11. Creating their own private and public: the male homosexual life space in a Nordic city during high modernity.

    Science.gov (United States)

    Nilsson, A

    1998-01-01

    In this article I describe the male homosexual life space in a Nordic city during the decades around the Second World War. It consisted almost entirely of outdoor places such as parks, public conveniencies, and streets. It included, in Delph's (1978) words, not only erotic, but also cultural and social oases, fostering an extensive and varied social life and a growing community. Most of this outdoor space was invisible to those other than the participants. It had its own differentiation of, and meanings for, "public" and "private." A poor economy, overcrowding, and the classical modern city helped shape the location and design of the male homosexual life space, as did the participation of many men who did not look upon themselves as "homosexual." During this period, and especially after the Second World War, this life space began to change in a direction pointing towards that of today, that is, towards less outdoor life and more life in homes and semipublic indoor spaces. Better economy, the rise of the welfare state, and diminished overcrowding furthered this movement. Among other things, these changes stimulated the withdrawal of men who did not see themselves as "homosexual." The transformation of the city into the spread out, suburbanized city, with segregation of various functions, contributed to the development, as did the obstruction of parks and toilets as meeting places by public authorities. The law reform of 1944, which decriminalized homosexual erotic acts between adults, was also of importance.

  12. The effect of structural complexity, prey density, and "predator-free space" on prey survivorship at created oyster reef mesocosms

    Science.gov (United States)

    Humphries, Austin T.; La Peyre, Megan K.; Decossas, Gary A.

    2011-01-01

    Interactions between predators and their prey are influenced by the habitat they occupy. Using created oyster (Crassostrea virginica) reef mesocosms, we conducted a series of laboratory experiments that created structure and manipulated complexity as well as prey density and “predator-free space” to examine the relationship between structural complexity and prey survivorship. Specifically, volume and spatial arrangement of oysters as well as prey density were manipulated, and the survivorship of prey (grass shrimp, Palaemonetes pugio) in the presence of a predator (wild red drum, Sciaenops ocellatus) was quantified. We found that the presence of structure increased prey survivorship, and that increasing complexity of this structure further increased survivorship, but only to a point. This agrees with the theory that structural complexity may influence predator-prey dynamics, but that a threshold exists with diminishing returns. These results held true even when prey density was scaled to structural complexity, or the amount of “predator-free space” was manipulated within our created reef mesocosms. The presence of structure and its complexity (oyster shell volume) were more important in facilitating prey survivorship than perceived refugia or density-dependent prey effects. A more accurate indicator of refugia might require “predator-free space” measures that also account for the available area within the structure itself (i.e., volume) and not just on the surface of a structure. Creating experiments that better mimic natural conditions and test a wider range of “predator-free space” are suggested to better understand the role of structural complexity in oyster reefs and other complex habitats.

  13. Void Statistics and Void Galaxies in the 2dFGRS

    CERN Document Server

    von Benda-Beckmann, Alexander M

    2007-01-01

    For the 2dFGRS we study the properties of voids and of fainter galaxies within voids that are defined by brighter galaxies. Our results are compared with simulated galaxy catalogues from the Millenium simulation coupled with a semianalytical galaxy formation recipe. We derive the void size distribution and discuss its dependence on the faint magnitude limit of the galaxies defining the voids. While voids among faint galaxies are typically smaller than those among bright galaxies, the ratio of the void sizes to the mean galaxy separation reaches larger values. This is well reproduced in the mock galaxy samples studied. We provide analytic fitting functions for the void size distribution. Furthermore, we study the galaxy population inside voids defined by objects with $B_J -5\\log{h}< -20$ and diameter larger than 10 \\hMpc. We find a clear bimodality of the void galaxies similar to the average comparison sample. We confirm the enhanced abundance of galaxies in the blue cloud and a depression of the number of ...

  14. Cluster-Void Degeneracy Breaking: Dark Energy, Planck and the Largest Cluster & Void

    CERN Document Server

    Sahlén, Martin; Silk, Joseph

    2015-01-01

    Combining galaxy cluster and void abundances breaks the degeneracy between mean matter density $\\Omega_{\\rm m}$ and power spectrum normalization $\\sigma_8$. In a first for voids, we constrain $\\Omega_{\\rm m} = 0.21 \\pm 0.10$ and $\\sigma_8 = 0.95 \\pm 0.21$ for a flat $\\Lambda$CDM universe, using extreme-value statistics on the claimed largest cluster and void. The Planck-consistent results detect dark energy with two objects, independently of other dark energy probes. Cluster-void studies also offer complementarity in scale, density, and non-linearity - of particular interest for testing modified-gravity models.

  15. Cosmic Voids in the SDSS DR12 BOSS Galaxy Sample: The Alcock-Paczynski Test

    CERN Document Server

    Mao, Qingqing; Scherrer, Robert J; Neyrinck, Mark C; Scoccimarro, Roman; Tinker, Jeremy L; McBride, Cameron K

    2016-01-01

    We apply the Alcock-Paczynski (AP) test to the stacked voids identified using the large-scale structure galaxy catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital Sky Survey (SDSS) Data Release 12 and is the final catalog of SDSS-III. We also use 1000 mock galaxy catalogs that match the geometry, density, and clustering properties of the BOSS sample in order to characterize the statistical uncertainties of our measurements and take into account systematic errors such as redshift space distortions. For both BOSS data and mock catalogs, we use the ZOBOV algorithm to identify voids, we stack together all voids with effective radii of 30-100Mpc/h in the redshift range 0.43-0.7, and we accurately measure the shape of the stacked voids. Our tests with the mock catalogs show that we measure the stacked void ellipticity with a statistical precision of 2.6%. We find that the stacked voids in redshift space are slightly squashed along the line of sight, whic...

  16. A Study of Fluctuations of Voids in Relativistic Ion-Ion Collisions

    CERN Document Server

    Ahmad, Shakeel; Khan, Shaista; Khatun, A; Irfan, M

    2015-01-01

    Event-by-event fluctuations (ebe) of hadronic patterns are investigated in terms of voids by analyzing the experimental data on 4.5, 14.5 and 60A GeV/c 16O-AgBr collisions. The findings are compared with the predictions of a multi-phase transport AMPT model. Dependence of voids on phase space bin width is examined in terms of two lowest moments of event-by-event fluctuations of voids, and Sq. The findings reveal that scaling exponent estimated from the observed power-law behavior of the voids may be used to characterize the various properties of hadronic phase transition. The results also rule out occurrence of 2nd order quark-hadron phase transition at the projectile energies considered.

  17. Influence of bulk dielectric polarization and void geometry upon PD transients

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Crichton, George C

    1999-01-01

    The induced charge arising from a partial discharge consists of a component associated with the actual space charge in the void, and one related to changes in the polarization of the bulk dielectric. These changes are brought about by the field produced by the space charge. The influence of the v...

  18. Influence of bulk dielectric polarization upon partial discharge transients: Effect of void geometry and orientation

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson; Crichton, G.C.

    2005-01-01

    The induced charge arising from a partial discharge consists of 2 components. One is associated with the actual space charge in the void. The other is related to changes in the polarization of the bulk dielectric. These changes are a direct consequence of the field produced by the space charge. T...

  19. Creating Spaces for Constructing Practice and Identity: Innovations of Teachers of English Language to Young Learners in Vietnam

    Science.gov (United States)

    Nguyen, Chinh Duc

    2017-01-01

    The discourse on construction of practice and identity in language teaching has been situated in transnational contexts. However, not all teachers are provided with access to transnational spaces for professional development. Drawing on the concept of "multimembership" in "multicommunities", this study explores how Vietnamese…

  20. Creating Spaces for Constructing Practice and Identity: Innovations of Teachers of English Language to Young Learners in Vietnam

    Science.gov (United States)

    Nguyen, Chinh Duc

    2017-01-01

    The discourse on construction of practice and identity in language teaching has been situated in transnational contexts. However, not all teachers are provided with access to transnational spaces for professional development. Drawing on the concept of "multimembership" in "multicommunities", this study explores how Vietnamese…

  1. Lavakujunduse nähtamatust olekust. Mängu esteetika lavaruumi loomisel / The Invisible Dimension of Scenography. Aesthetics of Play in Creating Stage Space

    Directory of Open Access Journals (Sweden)

    Liina Unt

    2014-12-01

    Full Text Available The comparison between theatre and playing has spread on many levels, from metaphors to sayings, aesthetic concepts to deterministic models. This paper examines scenography as an active play environment. Play, in the context of theatre space, is defined according to the classical characteristic features of playing: spatial and temporal limits, fictionality that runs in parallel with everyday reality, and direct involvement.  The paper focuses on the specific aspects of play environment as it appears in the Tartu New Theatre’s performances of „The Death of the Author“ and „The Beatles of Vanemuine“. Both productions are set in fictional locations with a visually static set design. Both are unique in that different locations are created without changing the physical space on stage – places appear and disappear through the performances, created by an odd textual allusion or two, or the audience’s imagination. The changes can be understood through the audience’s corporal perception, which this paper interprets using Merleau-Ponty’s phenomenological concept of corporeity.  Using Tartu New Theatre’s stage practice and Hans-Georg Gadamer’s hermeneutic aesthetics, the paper aims to answer the question: what is the aesthetic structure of such stage environments and how can an environmental experience be created, if the direct interference in space is minimal. Gadamer’s aesthetic concept revolves around play, interpreting works of art as a structure, a meaningful whole that can be presented and comprehended repeatedly. However, he qualifies that the structure, itself, is also a play as, despite a theoretic unity, it only exists when it is played. In this case, the scenography becomes an environment with open meanings, where attributing meaning and function happens through the agreements made during the act of playing, which don’t necessarily also imply physical changes to the environment. The environment is an agreed-upon space

  2. 38 CFR 3.207 - Void or annulled marriage.

    Science.gov (United States)

    2010-07-01

    ... 38 Pensions, Bonuses, and Veterans' Relief 1 2010-07-01 2010-07-01 false Void or annulled marriage... Void or annulled marriage. Proof that a marriage was void or has been annulled should consist of: (a... marriage void, together with such other evidence as may be required for a determination. (b) Annulled....

  3. Multiple void interaction of pipeline steel in triaxial stress fields

    Institute of Scientific and Technical Information of China (English)

    Bao-wen QIU; Ze-xi YUAN; Gui-feng ZHOU

    2008-01-01

    Three-dimensional unit cell models were developed to study the damage induced by void growth in ductile materials. Special emphasis is given to the influence of the void shape and random spatial void arrangements. The periodical void arrays of body cen-tered cubic are investigated by analyzing representative unit cells. The isotropic behavior of the matrix material is modeled using v. Mises plasticity. The cell models are analyzed by the large strain finite element method under monotonic loading while keeping the constant stress triaxiality. Results showed that when void density increased, effects of void aspects on void growth gradu-ally diminished.

  4. Universal void density profiles from simulation and SDSS

    CERN Document Server

    Nadathur, S; Diego, J M; Iliev, I T; Gottlöber, S; Watson, W A; Yepes, G

    2014-01-01

    We discuss the universality and self-similarity of void density profiles, for voids in realistic mock luminous red galaxy (LRG) catalogues from the Jubilee simulation, as well as in void catalogues constructed from the SDSS LRG and Main Galaxy samples. Voids are identified using a modified version of the ZOBOV watershed transform algorithm, with additional selection cuts. We find that voids in simulation are self-similar, meaning that their average rescaled profile does not depend on the void size, or -- within the range of the simulated catalogue -- on the redshift. Comparison of the profiles obtained from simulated and real voids shows an excellent match. The profiles of real voids also show a universal behaviour over a wide range of galaxy luminosities, number densities and redshifts. This points to a fundamental property of the voids found by the watershed algorithm, which can be exploited in future studies of voids.

  5. Universal void density profiles from simulation and SDSS

    Science.gov (United States)

    Nadathur, S.; Hotchkiss, S.; Diego, J. M.; Iliev, I. T.; Gottlöber, S.; Watson, W. A.; Yepes, G.

    2016-10-01

    We discuss the universality and self-similarity of void density profiles, for voids in realistic mock luminous red galaxy (LRG) catalogues from the Jubilee simulation, as well as in void catalogues constructed from the SDSS LRG and Main Galaxy samples. Voids are identified using a modified version of the ZOBOV watershed transform algorithm, with additional selection cuts. We find that voids in simulation are self-similar, meaning that their average rescaled profile does not depend on the void size, or - within the range of the simulated catalogue - on the redshift. Comparison of the profiles obtained from simulated and real voids shows an excellent match. The profiles of real voids also show a universal behaviour over a wide range of galaxy luminosities, number densities and redshifts. This points to a fundamental property of the voids found by the watershed algorithm, which can be exploited in future studies of voids.

  6. Post-void residual urine under 150 ml does not exclude voiding dysfunction in women

    DEFF Research Database (Denmark)

    Khayyami, Yasmine; Klarskov, Niels; Lose, Gunnar

    2016-01-01

    INTRODUCTION AND HYPOTHESIS: It has been claimed that post-void residual urine (PVR) below 150 ml rules out voiding dysfunction in women with stress urinary incontinence (SUI) and provides license to perform sling surgery. The cut-off of 150 ml seems arbitrary, not evidence-based, and so we sough...

  7. Autonomous selection of PDE inpainting techniques vs. exemplar inpainting techniques for void fill of high resolution digital surface models

    Science.gov (United States)

    Rahmes, Mark; Yates, J. Harlan; Allen, Josef DeVaughn; Kelley, Patrick

    2007-04-01

    High resolution Digital Surface Models (DSMs) may contain voids (missing data) due to the data collection process used to obtain the DSM, inclement weather conditions, low returns, system errors/malfunctions for various collection platforms, and other factors. DSM voids are also created during bare earth processing where culture and vegetation features have been extracted. The Harris LiteSite TM Toolkit handles these void regions in DSMs via two novel techniques. We use both partial differential equations (PDEs) and exemplar based inpainting techniques to accurately fill voids. The PDE technique has its origin in fluid dynamics and heat equations (a particular subset of partial differential equations). The exemplar technique has its origin in texture analysis and image processing. Each technique is optimally suited for different input conditions. The PDE technique works better where the area to be void filled does not have disproportionately high frequency data in the neighborhood of the boundary of the void. Conversely, the exemplar based technique is better suited for high frequency areas. Both are autonomous with respect to detecting and repairing void regions. We describe a cohesive autonomous solution that dynamically selects the best technique as each void is being repaired.

  8. Cosmic Voids: structure, dynamics and galaxies

    CERN Document Server

    van de Weygaert, Rien

    2009-01-01

    In this review we discuss several aspects of Cosmic Voids. Voids are a major component of the large scale distribution of matter and galaxies in the Universe. They are of instrumental importance for understanding the emergence of the Cosmic Web. Their relatively simple shape and structure makes them into useful tools for extracting the value of a variety cosmic parameters, possibly including even that of the influence of dark energy. Perhaps most promising and challenging is the issue of the galaxies found within their realm. Not only does the pristine environment of voids provide a promising testing ground for assessing the role of environment on the formation and evolution of galaxies, the dearth of dwarf galaxies may even represent a serious challenge to the standard view of cosmic structure formation.

  9. Void coalescence within periodic clusters of particles

    Science.gov (United States)

    Thomson, C. I. A.; Worswick, M. J.; Pilkey, A. K.; Lloyd, D. J.

    2003-01-01

    The effect of particle clustering on void damage rates in a ductile material under triaxial loading conditions is examined using three-dimensional finite element analysis. An infinite material containing a regular distribution of clustered particles is modelled using a unit cell approach. Three discrete particles are introduced into each unit cell while a secondary population of small particles within the surrounding matrix is represented using the Gurson-Tvergaard-Needleman (GTN) constitutive equations. Deformation strain states characteristic of sheet metal forming are considered; that is, deep drawing, plane strain and biaxial stretching. Uniaxial tensile stress states with varying levels of superimposed hydrostatic tension are also examined. The orientation of a particle cluster with respect to the direction of major principal loading is shown to significantly influence failure strains. Coalescence of voids within a first-order particle cluster (consisting of three particles) is a stable event while collapse of inter-cluster ligaments leads to imminent material collapse through void-sheeting.

  10. Effectiveness of tolterodine in nonneurogenic voiding dysfunction.

    Science.gov (United States)

    Babu, Ramesh

    2006-11-01

    The efficacy of tolterodine was analysed in children with non-neurogenic voiding dysfunction, using dysfunctional voiding symptom score (DVSS). Of 44 patients (mean age 9.3 yrs; M:F = 25:19), 36 received long acting tolterodine tartrate at a dose of 2mg OD and 8 at a dose of 4mg OD. The mean (SD) DVSS before and after the treatment was 17.1 (2.8) and 12.0 (2.4). There was a significant improvement in the mean DVSS score at the end of the treatment (Students t test P tolterodine is effective in children with voiding dysfunction. The single daily dose has good compliance and minimal side effect profile.

  11. ARDUSAT, an Arduino-Based CubeSat Providing Students with the Opportunity to Create their own Satellite Experiment and Collect Real-World Space Data

    Science.gov (United States)

    Geeroms, D.; Bertho, S.; De Roeve, M.; Lempens, R.; Ordies, M.; Prooth, J.

    2015-09-01

    Short for “Arduino Satellite”, ArduSat is an open-source Nanosatellite, based on the CubeSat standard. The extensive Arduino sensor suite on board gives students the opportunity to create their own satellite experiments and collect real-world space data using the Arduino open-source prototyping platform. From March until May 2014, two undergraduate physics students from Hasselt University used the downloadable ArduSat Software Development Kit which allowed them to design the command sequences they used to conduct their experiments.

  12. 'Black holes': escaping the void.

    Science.gov (United States)

    Waldron, Sharn

    2013-02-01

    The 'black hole' is a metaphor for a reality in the psyche of many individuals who have experienced complex trauma in infancy and early childhood. The 'black hole' has been created by an absence of the object, the (m)other, so there is no internalized object, no (m)other in the psyche. Rather, there is a 'black hole' where the object should be, but the infant is drawn to it, trapped by it because of an intrinsic, instinctive need for a 'real object', an internalized (m)other. Without this, the infant cannot develop. It is only the presence of a real object that can generate the essential gravity necessary to draw the core of the self that is still in an undeveloped state from deep within the abyss. It is the moving towards a real object, a (m)other, that relativizes the absolute power of the black hole and begins a reformation of its essence within the psyche.

  13. Thymic Nurse Cells Exhibit Epithelial Progenitor Phenotype and Create Unique Extra-Cytoplasmic Membrane Space for Thymocyte Selection

    Science.gov (United States)

    Hendrix, Tonya M.; Chilukuri, Rajendra V.E.; Martinez, Marcia; Olushoga, Zachariah; Blake, Andrew; Brohi, Moazzam; Walker, Christopher; Samms, Michael; Guyden, Jerry C.

    2010-01-01

    Thymic nurse cells (TNCs) are epithelial cells in the thymic cortex that contain as many as fifty thymocytes within specialized cytoplasmic vacuoles. The function of this cell-in-cell interaction has created controversy since their discovery in 1980. Further, some skepticism exists about the idea that apoptotic thymocytes within the TNC complex result from negative selection, a process believed to occur exclusively within the medulla. In this report, we have microscopic evidence that defines a unique membranous environment wherein lipid raft aggregates around the αβTCR expressed on captured thymocytes and class II MHC molecules expressed on TNCs. Further, immunohistological examination of thymic sections show TNCs located within the cortico-medullary junction to express cytokeratins five and eight (K5 and K8), and the transcription factor Trp-63, the phenotype defined elsewhere as the thymic epithelial progenitor subset. Our results suggest that the microenvironment provided by TNCs plays an important role in thymocyte selection as well as the potential for TNCs to be involved in the maintenance of thymic epithelia. PMID:20035931

  14. Malposition of catheters during voiding cystourethrography

    Energy Technology Data Exchange (ETDEWEB)

    Rathaus, V.; Konen, O.; Shapiro, M. [Dept. of Diagnostic Imaging Sapir Medical Center, Kfar-Saba and Sackler Medical School, Tel Aviv University (Israel); Grunebaum, M. [Veteran Pediatric Radiologist, Kfar Saba (Israel)

    2001-04-01

    The aim of this study was to report catheter malposition during voiding cystourethrography. Eight hundred forty-three voiding cystourethrography (265 males and 578 females, aged 1 week to 12 years, mean age 2 years) were performed during a period of 4 years. The conventional standard procedure was applied. In 3 cases with passed history of urinary tract infection the catheter entered directly into the ureter. In all these cases the uretero-vesical reflux was present on the same side where the catheter entered. It appears that insertion of a catheter into the ureter is possible only in the presence of an anomaly or pathology at the vesicoureteric junction. (orig.)

  15. Modification of SRIM-calculated dose and injected ion profiles due to sputtering, injected ion buildup and void swelling

    Science.gov (United States)

    Wang, Jing; Toloczko, Mychailo B.; Bailey, Nathan; Garner, Frank A.; Gigax, Jonathan; Shao, Lin

    2016-11-01

    In radiation effects on materials utilizing self-ion irradiations, it is necessary to calculate the local displacement damage level and ion injection profile because of the short distance that self-ions travel in a material and because of the strong variation of displacement rate with depth in a specimen. The most frequently used tool for this is the software package called Stopping and Range of Ions in Matter (SRIM). A SRIM-calculated depth-dependent dose level is usually determined under the implicit assumption that the target does not undergo any significant changes in volume during the process, in particular SRIM ignores the effect of sputtering, injected ions, and void swelling on the redistribution of the dose and injected ion profiles. This approach become increasingly invalid as the ion fluence reaches ever higher levels, especially for low energy ion irradiations. The original surface is not maintained due to sputter-induced erosion, while within the irradiated region of the specimen, injected ions are adding material, and if void swelling is occurring, it is creating empty space. An iterative mathematical treatment of SRIM outputs to produce corrected dose and injected ion profiles based on these phenomenon and without regard to diffusion is presented along with examples of differences between SRIM-calculated values and corrected values over a range of typical ion energies. The intent is to provide the reader with a convenient tool for more accurately calculating dose and injected ion profiles for heavy-ion irradiations.

  16. Modification of SRIM-calculated dose and injected ion profiles due to sputtering, injected ion buildup and void swelling

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Jing; Toloczko, Mychailo B.; Bailey, Nathan; Garner, Frank A.; Gigax, Jonathan; Shao, Lin

    2016-11-01

    In radiation effects on materials utilizing self-ion irradiations, it is necessary to calculate the local displacement damage level and ion injection profile because of the short distance that self-ions travel in a material and because of the strong variation of displacement rate with depth in a specimen. The most frequently used tool for this is the software package called Stopping and Range of Ions in Matter (SRIM). A SRIM-calculated depth-dependent dose level is usually determined under the implicit assumption that the target does not undergo any significant changes in volume during the process, in particular SRIM ignores the effect of sputtering, injected ions, and void swelling on the redistribution of the dose and injected atom profiles. This approach become increasingly invalid as the ion fluence reaches ever higher levels, especially for low energy ion irradiations. The original surface is not maintained due to sputter-induced erosion, while within the irradiated region of the specimen, injected ions are adding material, and if void swelling is occurring, it is creating empty space. An iterative mathematical treatment of SRIM outputs to produce corrected dose and injected atom profiles is presented along with examples differences between SRIM-calculated values and corrected values over a range of typical ion energies.

  17. Void Reactivity Coefficient Analysis during Void Fraction Changes in Innovative BWR Assemblies

    Directory of Open Access Journals (Sweden)

    Andrius Slavickas

    2015-01-01

    Full Text Available The study of the void reactivity variation in innovative BWR fuel assemblies is presented in this paper. The innovative assemblies are loaded with high enrichment fresh UO2 and MOX fuels. UO2 fuel enrichment is increased above existing design limitations for LWR fuels (>5%. MOX fuel enrichment with fissile Pu content is established to achieve the same burnup level as that of high enrichment UO2 fuel. For the numerical analysis, the TRITON functional module of SCALE 6.1 code with the 238-group ENDF/B-VI cross section data library was applied. The investigation of the void reactivity feedback is performed in the entire 0–100% void fraction range. Higher values of void reactivity coefficient for assembly loaded with MOX fuel are found in comparison with values for assembly loaded with UO2 fuel. Moreover, coefficient values for MOX fuel are positive over 75% void fraction. The variation of the void reactivity coefficient is explained by the results of the decomposition analysis based on four-factor formula and neutron absorption reactions for main isotopes. Additionally, the impact of the moderation enhancement on the void reactivity coefficient was investigated for the innovative assembly with MOX fuel.

  18. Cosmic Voids and Void Lensing in the Dark Energy Survey Science Verification Data

    CERN Document Server

    Sánchez, C; Kovacs, A; Jain, B; García-Bellido, J; Nadathur, S; Gruen, D; Hamaus, N; Huterer, D; Vielzeuf, P; Amara, A; Bonnett, C; DeRose, J; Hartley, W G; Jarvis, M; Lahav, O; Miquel, R; Rozo, E; Rykoff, E S; Sheldon, E; Wechsler, R H; Zuntz, J; Abbott, T M C; Abdalla, F B; Annis, J; Benoit-Lévy, A; Bernstein, G M; Bernstein, R A; Bertin, E; Brooks, D; Buckley-Geer, E; Rosell, A Carnero; Kind, M Carrasco; Carretero, J; Crocce, M; Cunha, C E; D'Andrea, C B; da Costa, L N; Desai, S; Diehl, H T; Dietrich, J P; Doel, P; Evrard, A E; Neto, A Fausti; Flaugher, B; Fosalba, P; Frieman, J; Gaztanaga, E; Gruendl, R A; Gutierrez, G; Honscheid, K; James, D J; Krause, E; Kuehn, K; Lima, M; Maia, M A G; Marshall, J L; Melchior, P; Plazas, A A; Reil, K; Romer, A K; Sanchez, E; Schubnell, M; Sevilla-Noarbe, I; Smith, R C; Soares-Santos, M; Sobreira, F; Suchyta, E; Tarle, G; Thomas, D; Walker, A R; Weller, J

    2016-01-01

    Galaxies and their dark matter halos populate a complicated filamentary network around large, nearly empty regions known as cosmic voids. Cosmic voids are usually identified in spectroscopic galaxy surveys, where 3D information about the large-scale structure of the Universe is available. Although an increasing amount of photometric data is being produced, its potential for void studies is limited since photometric redshifts induce line-of-sight position errors of $\\sim50$ Mpc/$h$ or more that can render many voids undetectable. In this paper we present a new void finder designed for photometric surveys, validate it using simulations, and apply it to the high-quality photo-$z$ redMaGiC galaxy sample of the Dark Energy Survey Science Verification (DES-SV) data. The algorithm works by projecting galaxies into 2D slices and finding voids in the smoothed 2D galaxy density field of the slice. Fixing the line-of-sight size of the slices to be at least twice the photo-$z$ scatter, the number of voids found in these ...

  19. The sparkling Universe: a scenario for cosmic void motions

    Science.gov (United States)

    Ceccarelli, Laura; Ruiz, Andrés N.; Lares, Marcelo; Paz, Dante J.; Maldonado, Victoria E.; Luparello, Heliana E.; Garcia Lambas, Diego

    2016-10-01

    Cosmic voids are prominent features of the Universe, encoding relevant information of the growth and evolution of structure through their dynamics. Here, we perform a statistical study of the global motion of cosmic voids using both a numerical simulation and observational data. Their relation to large-scale mass flows and the physical effects that drive those motions. We analyse the bulk motions of voids, finding void mean bulk velocities in the range 300-400 km s-1, depending on void size and the large-scale environment. Statistically, small voids move faster, and voids in relatively higher density environments have higher bulk velocities. Also, we find large-scale overdensities (underdensities) along (opposite to) the void motion direction, suggesting that void motions respond to a pull-push mechanism. Our analysis suggests that their relative motions are generated by large-scale density fluctuations. In agreement with linear theory, voids embedded in low (high) density regions mutually recede (attract) each other, providing the general mechanism to understand the bimodal behaviour of void motions. We have also inferred void motions in the Sloan Digital Sky Survey using linear theory, finding that their estimated motions are in qualitatively agreement with the results of the simulation. Our results suggest a scenario of galaxies and galaxy systems flowing away from void centres with the additional, and more relevant, contribution of the void bulk motion to the total velocity.

  20. Building Different Levels of Legitimacy in Internationalisation: Subsidiary – Civil Society Nexus in Institutional Void

    DEFF Research Database (Denmark)

    Rana, Mohammad Bakhtiar; Sørensen, Olav Jull

    2016-01-01

    .e. degree) of legitimacy- acceptance, image, endorsement, and synergy (acceptance + efficiency) subsidiaries earn, develop, or co-develop in collaboration with CS actors in internationalization. Our study brings a new insight on legitimacy theory in international management that isomorphism perspective...... of legitimacy cannot explain the complexity of subsidiary legitimization in institutional void. Because, subsidiaries not only earn acceptance in institutional context, they also create and co-create image, endorsement, and synergy. We thus combine institutional isomorphism and institutional innovation...

  1. Strong coupling in porphyrin J-aggregate excitons and plasmons in nano-void arrays

    Science.gov (United States)

    Ferdele, Stefano; Jose, Bincy; Foster, Robert; Keyes, Tia E.; Rice, James H.

    2017-10-01

    Active plasmonic nano-void arrays made through colloidal lithography (a cost effective and rapid process) potentially offers opportunities for scalable device design. In this work we demonstrate strong coupling between Bragg-like quadrupole surface plasmon modes in nano-void substrate designs with Frankel excitons in a molecular J-aggregate layer though angular tuning. The enhanced exciton-plasmon coupling creates a Fano like line shape in the differential reflection spectra associated with the formation of new hybrid states, leading to anti-crossing of the upper and lower polaritons with a Rabi frequency of 120 meV.

  2. Large Voids in the Universe are Really Empty

    Science.gov (United States)

    1996-07-01

    Motions of Nearby Galaxies Reveal No Invisible Matter Using telescopes in Chile, Europe, Australia and the USA, an international team of astronomers [1] has discovered large empty regions (`holes') in what they refer to as the `local Universe'. These regions, as well as others with excess mass density are revealed by a study of the motions in space of more than 2000 galaxies. They are among the largest structures ever seen in the Universe and have diameters of up to 100 million light years. Large empty regions in the nearby Universe Astronomers have known for a number of years that there are regions in the Universe where no galaxies, stars or gas can be seen by optical telescopes. In professional language, such `holes' are commonly referred to as `voids' . For some time, astronomers around the world have tried to detect at least some galaxies in these voids by using larger and more sensitive telescopes. Amazingly, only few such galaxies have ever been found, even by use of the best available equipment. The failure to detect anything in these voids has led to speculations about the nature of the matter in voids. Could it be that it is there, but not in the form astronomers are best familiar with, namely stars and galaxies which can be detected with modern telescopes? Is it perhaps in some kind of exotic, invisible state? The new study now gives a surprisingly simple answer to that question: There just is no matter in the voids! How to detect the `voids' Astronomers can easily detect normal galaxies at very large distances with the help of technologically advanced optical telescopes, like the ones operated by the European Southern Observatory at La Silla in Chile. It was during such investigations in the 1980's, at ESO and elsewhere, that some `voids' were first found as regions of space where few galaxies could be seen. However, it is very difficult to prove that there is `nothing', i.e. absence of visible as well as invisible matter, in some region of the Universe

  3. Measurement of post-void residual urine

    NARCIS (Netherlands)

    Asimakopoulos, Anastasios D.; De Nunzio, Cosimo; Kocjancic, Ervin; Tubaro, Andrea; Rosier, Peter F.; Finazzi-Agrò, Enrico

    2016-01-01

    Aims To present the teaching module "Measurement of Post-void residual urine." Methods This module has been prepared by a Working Group of the ICS Urodynamics Committee. The methodology used included comprehensive literature review, consensus formation by the members of the Working Group, and review

  4. Void fraction instrument acceptance test procedure

    Energy Technology Data Exchange (ETDEWEB)

    Pearce, K.L.

    1994-09-15

    This acceptance test procedure (ATP) was written to test the void fraction instrument (VFI) and verify that the unit is ready for field service. The procedure verifies that the mechanical and electrical features (not specifically addressed in the software ATP) and software alarms are operating as designed.

  5. Halo abundances and shear in void models

    DEFF Research Database (Denmark)

    Alonso, David; García-Bellido, Juan; Haugbølle, Troels

    2012-01-01

    We study the non-linear gravitational collapse of dark matter into halos through numerical N-body simulations of Lemaitre-Tolman-Bondi void models. We extend the halo mass function formalism to these models in a consistent way. This extension not only compares well with the simulated data at all ...

  6. Halo abundances and shear in void models

    DEFF Research Database (Denmark)

    Alonso, David; García-Bellido, Juan; Haugbølle, Troels;

    2012-01-01

    We study the non-linear gravitational collapse of dark matter into halos through numerical N-body simulations of Lemaitre-Tolman-Bondi void models. We extend the halo mass function formalism to these models in a consistent way. This extension not only compares well with the simulated data at all...

  7. Void fraction instrument acceptance test procedure

    Energy Technology Data Exchange (ETDEWEB)

    Pearce, K.L.

    1994-09-15

    This acceptance test procedure (ATP) was written to test the void fraction instrument (VFI) and verify that the unit is ready for field service. The procedure verifies that the mechanical and electrical features (not specifically addressed in the software ATP) and software alarms are operating as designed.

  8. "Dark energy" in the Local Void

    Science.gov (United States)

    Villata, M.

    2012-05-01

    The unexpected discovery of the accelerated cosmic expansion in 1998 has filled the Universe with the embarrassing presence of an unidentified "dark energy", or cosmological constant, devoid of any physical meaning. While this standard cosmology seems to work well at the global level, improved knowledge of the kinematics and other properties of our extragalactic neighborhood indicates the need for a better theory. We investigate whether the recently suggested repulsive-gravity scenario can account for some of the features that are unexplained by the standard model. Through simple dynamical considerations, we find that the Local Void could host an amount of antimatter (˜5×1015 M ⊙) roughly equivalent to the mass of a typical supercluster, thus restoring the matter-antimatter symmetry. The antigravity field produced by this "dark repulsor" can explain the anomalous motion of the Local Sheet away from the Local Void, as well as several other properties of nearby galaxies that seem to require void evacuation and structure formation much faster than expected from the standard model. At the global cosmological level, gravitational repulsion from antimatter hidden in voids can provide more than enough potential energy to drive both the cosmic expansion and its acceleration, with no need for an initial "explosion" and dark energy. Moreover, the discrete distribution of these dark repulsors, in contrast to the uniformly permeating dark energy, can also explain dark flows and other recently observed excessive inhomogeneities and anisotropies of the Universe.

  9. The Metallicity of Void Dwarf Galaxies

    NARCIS (Netherlands)

    Kreckel, K.; Croxall, K.; Groves, B.; van de Weygaert, R.; Pogge, R. W.

    2015-01-01

    The current ΛCDM cosmological model predicts that galaxy evolution proceeds more slowly in lower density environments, suggesting that voids are a prime location to search for relatively pristine galaxies that are representative of the building blocks of early massive galaxies. To test the assumptio

  10. Partial discharges in ellipsoidal and spheroidal voids

    DEFF Research Database (Denmark)

    Crichton, George C; Karlsson, P. W.; Pedersen, Aage

    1989-01-01

    Transients associated with partial discharges in voids can be described in terms of the charges induced on the terminal electrodes of the system. The relationship between the induced charge and the properties which are usually measured is discussed. The method is illustrated by applying it to a s...

  11. Space-Mass Relation And Gravity In A Geometrically Open Space Universe

    Directory of Open Access Journals (Sweden)

    Saravanan Govindaraj

    2015-04-01

    Full Text Available Abstract Gravity is a property of space-time fabric and not a universal force of attraction between two objects with mass. Considering that energy is distributed in space-time while mass replaces space-time from its place producing a denser or warped space-time around the mass problems regarding the nature of gravity can be addressed. This paper talks about understanding the nature of gravity as a virtual force created by warped space time and also explains what gives a particle its mass. Irrespective of mass gravity can exist anywhere in the universe but can be experienced only by the presence of mass or by distributing of energy through it. Mass is a void in space-time but in real world matter exists in their smallest form as sub-atomic particles separated with a space-time. If a particle is said to have a greater energy then it has created a relatively bigger void in space-time.

  12. Failure by void coalescence in metallic materials containing primary and secondary voids subject to intense shearing

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau; Tvergaard, Viggo

    2011-01-01

    , subject to shear dominated loading. To account for both length scales involved in this study, a continuum model that includes the softening effect of damage evolution in shear is used to represent the matrix material surrounding the primary voids. Here, a recently extended Gurson-type model is used, which......Failure under intense shearing at close to zero stress triaxiality is widely observed for ductile metallic materials, and is identified in experiments as smeared-out dimples on the fracture surface. Numerical cell-model studies of equal sized voids have revealed that the mechanism governing...... secondary damage that co-exists with or nucleation in the ligaments between larger voids that coalesce during intense shearing. A numerical cell-model study is carried out to gain a parametric understanding of the overall material response for different initial conditions of the two void populations...

  13. Discussion on the creating principle of primary school activity space%初探小学活动空间的营造原则

    Institute of Scientific and Technical Information of China (English)

    王栋

    2015-01-01

    Based on the current actual requirements,combining with two excellent design examples of Tsinghua University elementary school and Xiaoquan national primary school,from the convenience,diversity,size appropriate three aspects of space activities discussed the creating princi-ple of primary school activity space,made the design scheme to meet the space environment and atmosphere of learning and communication,pro-moted the healthy development of student’s body and mind.%立足于现阶段的现实需求,结合清华大学附小和孝泉民族小学两个优秀的设计实例,从活动空间的便捷性、多样性、尺度的适宜性三个方面探讨了小学活动空间的营造原则,使设计方案能满足学习和交往的空间环境和氛围,促进学生身心的健康发展。

  14. A Cosmic Watershed: the WVF Void Detection Technique

    CERN Document Server

    Platen, Erwin; Jones, Bernard J T

    2007-01-01

    On megaparsec scales the Universe is permeated by an intricate filigree of clusters, filaments, sheets and voids, the Cosmic Web. For the understanding of its dynamical and hierarchical history it is crucial to identify objectively its complex morphological components. One of the most characteristic aspects is that of the dominant underdense Voids, the product of a hierarchical process driven by the collapse of minor voids in addition to the merging of large ones. In this study we present an objective void finder technique which involves a minimum of assumptions about the scale, structure and shape of voids. Our void finding method, the Watershed Void Finder (WVF), is based upon the Watershed Transform, a well-known technique for the segmentation of images. Importantly, the technique has the potential to trace the existing manifestations of a void hierarchy. The basic watershed transform is augmented by a variety of correction procedures to remove spurious structure resulting from sampling noise. This study c...

  15. Void lattice formation in electron irradiated CaF{sub 2}: Statistical analysis of experimental data and cellular automata simulations

    Energy Technology Data Exchange (ETDEWEB)

    Zvejnieks, G., E-mail: guntars@latnet.lv; Merzlyakov, P.; Kuzovkov, V.N.; Kotomin, E.A.

    2016-02-01

    Calcium fluoride (CaF{sub 2}) is an important optical material widely used in both microlithography and deep UV windows. It is known that under certain conditions electron beam irradiation can create therein a superlattice consisting of vacancy clusters (called a void lattice). The goal of this paper is twofold. Firstly, to perform a quantitative analysis of experimental TEM images demonstrating void lattice formation, we developed two distinct image filters. As a result, we can easily calculate vacancy concentration, vacancy cluster distribution function as well as average distances between defect clusters. The results for two suggested filters are similar and demonstrate that experimental void cluster growth is accompanied by a slight increase of the void lattice constant. Secondly, we proposed a microscopic model that allows us to reproduce a macroscopic void ordering, in agreement with experimental data, and to resolve existing theoretical and experimental contradictions. Our computer simulations demonstrate that macroscopic void lattice self-organization can occur only in a narrow parameter range. Moreover, we studied the kinetics of a void lattice ordering, starting from an initial disordered stage, in a good agreement with the TEM experimental data.

  16. POLAR DISK GALAXY FOUND IN WALL BETWEEN VOIDS

    NARCIS (Netherlands)

    Stanonik, K.; Platen, E.; Aragon-Calvo, M. A.; van Gorkom, J. H.; van de Weygaert, R.; van der Hulst, J. M.; Peebles, P. J. E.

    2009-01-01

    We have found an isolated polar disk galaxy in what appears to be a cosmological wall situated between two voids. This void galaxy is unique as its polar disk was discovered serendipitously in an Hi survey of SDSS void galaxies, with no optical counterpart to the Hi polar disk. Yet the Hi mass in th

  17. Void Coalescence Processes Quantified Through Atomistic and Multiscale Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Rudd, R E; Seppala, E T; Dupuy, L M; Belak, J

    2007-01-12

    Simulation of ductile fracture at the atomic scale reveals many aspects of the fracture process including specific mechanisms associated with void nucleation and growth as a precursor to fracture and the plastic deformation of the material surrounding the voids and cracks. Recently we have studied void coalescence in ductile metals using large-scale atomistic and continuum simulations. Here we review that work and present some related investigations. The atomistic simulations involve three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. No pronounced shear flow is found in the coalescence process. We also discuss a technique for optimizing the calculation of fine-scale information on the fly for use in a coarse-scale simulation, and discuss the specific case of a fine-scale model that calculates void growth explicitly feeding into a coarse-scale mechanics model to study damage localization.

  18. POLAR DISK GALAXY FOUND IN WALL BETWEEN VOIDS

    NARCIS (Netherlands)

    Stanonik, K.; Platen, E.; Aragon-Calvo, M. A.; van Gorkom, J. H.; van de Weygaert, R.; van der Hulst, J. M.; Peebles, P. J. E.

    2009-01-01

    We have found an isolated polar disk galaxy in what appears to be a cosmological wall situated between two voids. This void galaxy is unique as its polar disk was discovered serendipitously in an Hi survey of SDSS void galaxies, with no optical counterpart to the Hi polar disk. Yet the Hi mass in th

  19. Vacancy Migration and Void Formation in gamma-irradiated Ice

    DEFF Research Database (Denmark)

    Eldrup, Morten Mostgaard

    1976-01-01

    are ascribed to Ps inhibition and conversion by radiation created OH radicals. Heating above −165°C makes both effects disappear in agreement with radiation chemistry results on OH. Heating also increases the longest lifetime up to 11 nsec at −130°C. This is explained as vacancy migration leading to void......Positron annihilation techniques (PAT) have been used to study the effects in ice of γ irradiation at −196°C and of subsequent heating, both in poly‐ and monocrystalline samples. The main effects of irradiation are (1) the appearance in positron lifetime spectra of two long‐lived components (1...... formation. A vacancy migration energy is obtained, Em=0.34±0.07 eV, around three times higher than the previously assumed value. The advantage in this kind of study of using PAT, which are specifically sensitive to vacancy type defects, is pointed out....

  20. "Dark energy" in the Local Void

    CERN Document Server

    Villata, M

    2012-01-01

    The unexpected discovery of the accelerated cosmic expansion in 1998 has filled the Universe with the embarrassing presence of an unidentified "dark energy", or cosmological constant, devoid of any physical meaning. While this standard cosmology seems to work well at the global level, improved knowledge of the kinematics and other properties of our extragalactic neighborhood indicates the need for a better theory. We investigate whether the recently suggested repulsive-gravity scenario can account for some of the features that are unexplained by the standard model. Through simple dynamical considerations, we find that the Local Void could host an amount of antimatter ($\\sim5\\times10^{15}\\,M_\\odot$) roughly equivalent to the mass of a typical supercluster, thus restoring the matter-antimatter symmetry. The antigravity field produced by this "dark repulsor" can explain the anomalous motion of the Local Sheet away from the Local Void, as well as several other properties of nearby galaxies that seem to require vo...

  1. DIVE in the cosmic web: voids with Delaunay Triangulation from discrete matter tracer distributions

    CERN Document Server

    Zhao, Cheng; Liang, Yu; Kitaura, Francisco-Shu; Chuang, Chia-Hsun

    2015-01-01

    We present a novel parameter-free cosmological void finder (\\textsc{dive}, Delaunay TrIangulation Void findEr) based on Delaunay Triangulation (DT), which efficiently computes the empty spheres constrained by a discrete set of tracers. We define the spheres as DT voids, and describe their properties, including an universal density profile together with an intrinsic scatter. We apply this technique on 100 halo catalogues with volumes of 2.5\\,$h^{-1}$Gpc side each, with a bias and number density similar to the BOSS CMASS Luminous Red Galaxies, performed with the \\textsc{patchy} code. Our results show that there are two main species of DT voids, which can be characterised by the radius: they have different responses to halo redshift space distortions, to number density of tracers, and reside in different dark matter environments. Based on dynamical arguments using the tidal field tensor, we demonstrate that large DT voids are hosted in expanding regions, whereas the haloes used to construct them reside in collap...

  2. Molecular Gas and Star Formation in Voids

    CERN Document Server

    Das, M; Iono, D; Honey, M; Ramya, S

    2014-01-01

    We present the detection of molecular gas using CO(1-0) line emission and follow up Halpha imaging observations of galaxies located in nearby voids. The CO(1-0) observations were done using the 45m telescope of the Nobeyama Radio Observatory (NRO) and the optical observations were done using the Himalayan Chandra Telescope (HCT). Although void galaxies lie in the most under dense parts of our universe, a significant fraction of them are gas rich, spiral galaxies that show signatures of ongoing star formation. Not much is known about their cold gas content or star formation properties. In this study we searched for molecular gas in five void galaxies using the NRO. The galaxies were selected based on their relatively higher IRAS fluxes or Halpha line luminosities. CO(1--0) emission was detected in four galaxies and the derived molecular gas masses lie between (1 - 8)E+9 Msun. The H$\\alpha$ imaging observations of three galaxies detected in CO emission indicates ongoing star formation and the derived star forma...

  3. A simplified post preparation technique after Thermafil obturation: evaluation of apical microleakage and presence of voids using methylene blue dye penetration

    Science.gov (United States)

    Pusinanti, Luca; Rubini, Riccardo; Pellati, Agnese; Zerman, Nicoletta

    2013-01-01

    Summary Aim To evaluate the apical microleakage of Thermafil obturations after three different post space preparation techniques. Materials and methods 33 root canals of mono-radiculated extracted teeth were prepared with M two and then obturated with Thermafil. Teeth so treated were then divided into three groups and the post space to middle root was prepared using three different techniques. In samples in group A the housing for the post was created using a Torpan bur, and the carrier was partially removed only in the coronal portion. In samples in group B the carrier was completely removed and gutta-percha was hand compacted, before canal preparation using a Torpan bur. In samples in group C the carrier was completely removed, without guttapercha compaction, before canal preparation using a Torpan bur. The roots were immersed for 72 hours in methylene blue dye solution and sectioned transversely at 1-3-5 mm from the apex for evaluation of dye penetration using a stereomicroscope. The data collected were processed using Win CAD software and subjected to statistical analysis using the Student t test for p<0.05. Results There were no significant differences between the three groups, except for the presence of voids in the intermediate section of teeth in groups B and C. Conclusions Post space preparation did not influence the apical seal, and gutta-percha without voids was always found in the last millimetre of the canal obturation. This study proposes a post preparation technique which provides for complete carrier removal using pliers, hand compaction of residual gutta-percha with a manual plugger and enlargement of the root canal, using appropriate post space burs, free of any interference from the carrier. Operating time is reduced, as is the risk of creating ledges or iatrogenic perforations. PMID:23991269

  4. Development of video-assisted breast cancer surgery: Initial experience with a novel method for creating working space without prior liposuction.

    Science.gov (United States)

    Wu, Qian-Fu; Yu, Ying-Hua; Zhu, Xiao; Cui, Ying; Mo, Qin-Guo; Wei, Chang-Yuan; Lin, Xue-Juan; Liu, Xue-Ying; Xie, Wei-Kang; Gan, Shui; Lei, Wei

    2017-07-01

    Endoscopic techniques are promising in breast surgery. In order to create working space, liposuction is widely used in video-assisted breast surgery (VABS). However, the use of liposuction is likely associated with side effects that may partly limit the application of VABS. Therefore, a new technique of endoscopic axillary lymphadenectomy without prior liposuction was developed by our group. A total of 106 female patients underwent VABS, with special adaptation of the video-assisted surgical procedures previously described. Differing from other endoscopic surgery techniques, our adaptations of VABS included the selection of the working instruments, trocar placement, creation of working space, order of axillary lymph node dissection and method of mastectomy. The operative time was 50-180 min (mean, 85.5 min). The intraoperative blood loss ranged from 20 to 100 ml (mean, 48 ml). The mean lymph node number harvested was 11.5 (range, 6-31). No serious intra- or postoperative complications were recorded. There was no axillary tumor relapse, trocar site tumor implantation or upper limb edema. Without prior liposuction, our new technique of VABS reduced the blood loss volume, endoscopic surgery time, total volume of drainage fluid and, most importantly, the risk of port-site metastases. This new technique appears to have great clinical potential and good prospects for future endoscopic breast surgery development.

  5. Effect of the Entrained Air Void on Strength and Interfacial Transition Zone of Air-Entrained Mortar

    Institute of Scientific and Technical Information of China (English)

    GAO Hui; ZHANG Xiong; ZHANG Yongjuan

    2015-01-01

    In order to facilitate the development and application of air entraining agents (AEA) in the high performance concrete, entrained air void structure parameters (air void size range from 10 to 1 600 μm) of 28 d sifted mortar were measured by image analysis method. The relationship between the air void size distribution and strength of mortar was studied by methods of grey connection analysis and multiple linear regression analysis. The multiple linear regression equation was established with a correlation coefifcient of 0.966. The weight of the affection of hierarchical porosity on the compressive strength ratio was also obtained. In addition, the effect of air voids on the paste-aggregate interfacial transition zone (ITZ) was analyzed by microhardness. The results show that the correlation between different pore size range and the compressive strength is negative. The effect of air void size distribution on 28 days compressive strength is different: under the condition of similar total porosity, with the increase of the porosity of the air void size, ranging from 10 to 200 μm, and the decrease of the porosity, ranging from 200 to 1 600 μm, the average air void diameter and mean free spacing are decreased; as well as the width of ITZ. On the contrary, the microhardness of the ITZ is increased while the compressive strength loss is decreased.

  6. Nonlocal plasticity effects on interaction of different size voids

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Niordson, Christian Frithiof

    2004-01-01

    A nonlocal elastic-plastic material model is used to show that the rate of void growth is significantly reduced when the voids are small enough to be comparable with a characteristic material length. For a very small void in the material between much larger voids the competition between...... an increased growth rate due to the stress concentrations around the larger voids and a reduced growth rate due to the nonlocal effects is studied. The analyses are based on an axisymmetric unit cell model with special boundary conditions, which allow for a relatively simple investigation of a full three...

  7. The Mechanism of Hydrogen-facilitating Initiation of Voids

    Institute of Scientific and Technical Information of China (English)

    褚武扬; 蒋兴钢; 肖纪美

    1994-01-01

    By combining the hydrogen-induced local plastic deformation theory with the decohesive theory and the hydrogen pressure theory, a new mechanism of hydrogen-facilitating initiation of voids has been proposed. Through facilitating the local plastic deformation and reducing the cohesive strength, hydrogen promotes both initiating a nanocrack and blunting the nanocrack into a void, resulting in hydrogen-promoting initiation of the void. On the other hand, hydrogen can enhance the stability of the void through reducing the cohesive strength and forming a hydrogen pressure in the void.

  8. The Void Galaxy Survey: Photometry, structure and identity of void galaxies

    CERN Document Server

    Beygu, B; van der Hulst, J M; Jarrett, T H; Kreckel, K; van de Weygaert, R; van Gorkom, J H; Aragon-Calvo, M A

    2016-01-01

    We analyze photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6$\\mu$m and 4.5$\\mu$m Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the SDSS DR7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from $\\rm{M_B=-15.5}$ to $\\rm{M_B=-20}$, while at the 3.6$\\mu$m band their magnitudes range from $\\rm{M_{3.6}=-18}$ to $\\rm{M_{3.6}=-24}$. Their B-[3.6] colour and structural parameters indicate these are star forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than $3 \\times 10^{10}$ M$_\\odot$. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-t...

  9. Void Coalescence Processes Quantified through Atomistic and Multiscale Simulation

    Energy Technology Data Exchange (ETDEWEB)

    Rudd, R E; Seppala, E T; Dupuy, L M; Belak, J

    2005-12-31

    Simulation of ductile fracture at the atomic scale reveals many aspects of the fracture process including specific mechanisms associated with void nucleation and growth as a precursor to fracture and the plastic deformation of the material surrounding the voids and cracks. Recently we have studied void coalescence in ductile metals using large-scale atomistic and continuum simulations. Here we review that work and present some related investigations. The atomistic simulations involve three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. No pronounced shear flow is found in the coalescence process.

  10. A Cosmic Void Catalog of SDSS DR12 BOSS Galaxies

    Science.gov (United States)

    Mao, Qingqing; Berlind, Andreas A.; Scherrer, Robert J.; Neyrinck, Mark C.; Scoccimarro, Román; Tinker, Jeremy L.; McBride, Cameron K.; Schneider, Donald P.; Pan, Kaike; Bizyaev, Dmitry; Malanushenko, Elena; Malanushenko, Viktor

    2017-02-01

    We present a cosmic void catalog using the large-scale structure galaxy catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital Sky Survey (SDSS) Data Release 12 and is the final catalog of SDSS-III. We take into account the survey boundaries, masks, and angular and radial selection functions, and apply the ZOBOV void finding algorithm to the Galaxy catalog. We identify a total of 10,643 voids. After making quality cuts to ensure that the voids represent real underdense regions, we obtain 1,228 voids with effective radii spanning the range 20–100 {h}-1 {Mpc} and with central densities that are, on average, 30% of the mean sample density. We release versions of the catalogs both with and without quality cuts. We discuss the basic statistics of voids, such as their size and redshift distributions, and measure the radial density profile of the voids via a stacking technique. In addition, we construct mock void catalogs from 1000 mock galaxy catalogs, and find that the properties of BOSS voids are in good agreement with those in the mock catalogs. We compare the stellar mass distribution of galaxies living inside and outside of the voids, and find no large difference. These BOSS and mock void catalogs are useful for a number of cosmological and galaxy environment studies.

  11. Voiding dysfunction in children aged five to 15 years

    Directory of Open Access Journals (Sweden)

    Karaklajić Dragana

    2004-01-01

    Full Text Available Voiding dysfunction in children was analyzed in 91 patients in a period from January 1st to October 1st 1998. Most of the patients had functional voiding disorder (92.31%, and only 7.69% manifested monosymptomatic night enuresis. The number of girls was bigger in the group of patients with voiding dysfunction while the boys were predominant in the group with mono-symptomatic nocturnal enuresis. More than a half of children with functional voiding disorder had repeated urinal infections (58.23%, incontinence (93.49%, need for urgent voiding (68.13%, and vesicoureteral reflux (47.61%. The most common type of voiding dysfunction was urge syndrome/urge incontinence. The incidence of dysfunctional voiding disorder was more often in children with scaring changes of kidney which were diagnosed by static scintigraphy.

  12. Hot Spots. Urban Voids in the Palestinian city of Nazareth

    Directory of Open Access Journals (Sweden)

    Els Verbakel

    2014-12-01

    Full Text Available In the Palestinian city of Nazareth, visitors, passers-by and inhabitants incessantly experience the city’s urban voids; left-over spaces in-between a multiplicity of urban patches, sites that have been under dispute, that belong to many or to none. Sites where construction has start- ed but was interrupted, and frozen in time, urban squares and plazas where global tension dominates the streetscape. Properties where the family owning the land has grown so big it becomes impossible to reach an agreement on future plans. Over designed simulacra of the Italian piazza as a foreign visitor in the urban fabric, side by side with fields of an uncultivated and uninhabited landscape interrupting a dense and vibrant urban context, sometimes re-claimed temporarily by informal construction, graffiti, or wild growth of local species.

  13. The void galaxy survey: photometry, structure and identity of void galaxies

    Science.gov (United States)

    Beygu, B.; Peletier, R. F.; van der Hulst, J. M.; Jarrett, T. H.; Kreckel, K.; van de Weygaert, R.; van Gorkom, J. H.; Aragon-Calvo, M. A.

    2017-01-01

    We analyse photometry from deep B-band images of 59 void galaxies in the Void Galaxy Survey (VGS), together with their near-infrared 3.6 μm and 4.5 μm Spitzer photometry. The VGS galaxies constitute a sample of void galaxies that were selected by a geometric-topological procedure from the Sloan Digital Sky Survey Data Release 7 data release, and which populate the deep interior of voids. Our void galaxies span a range of absolute B-magnitude from MB = -15.5 to -20, while at the 3.6 μm band their magnitudes range from M3.6 = -18 to -24. Their B-[3.6] colour and structural parameters indicate these are star-forming galaxies. A good reflection of the old stellar population, the near-infrared band photometry also provide a robust estimate of the stellar mass, which for the VGS galaxies we confirm to be smaller than 3 × 1010 M⊙. In terms of the structural parameters and morphology, our findings align with other studies in that our VGS galaxy sample consists mostly of small late-type galaxies. Most of them are similar to Sd-Sm galaxies, although a few are irregularly shaped galaxies. The sample even includes two early-type galaxies, one of which is an AGN. Their Sérsic indices are nearly all smaller than n = 2 in both bands and they also have small half-light radii. In all, we conclude that the principal impact of the void environment on the galaxies populating them mostly concerns their low stellar mass and small size.

  14. The Void Galaxy Survey: Galaxy Evolution and Gas Accretion in Voids

    Science.gov (United States)

    Kreckel, Kathryn; van Gorkom, Jacqueline H.; Beygu, Burcu; van de Weygaert, Rien; van der Hulst, J. M.; Aragon-Calvo, Miguel A.; Peletier, Reynier F.

    2016-10-01

    Voids represent a unique environment for the study of galaxy evolution, as the lower density environment is expected to result in shorter merger histories and slower evolution of galaxies. This provides an ideal opportunity to test theories of galaxy formation and evolution. Imaging of the neutral hydrogen, central in both driving and regulating star formation, directly traces the gas reservoir and can reveal interactions and signs of cold gas accretion. For a new Void Galaxy Survey (VGS), we have carefully selected a sample of 59 galaxies that reside in the deepest underdensities of geometrically identified voids within the SDSS at distances of ~100 Mpc, and pursued deep UV, optical, Hα, IR, and HI imaging to study in detail the morphology and kinematics of both the stellar and gaseous components. This sample allows us to not only examine the global statistical properties of void galaxies, but also to explore the details of the dynamical properties. We present an overview of the VGS, and highlight key results on the HI content and individually interesting systems. In general, we find that the void galaxies are gas rich, low luminosity, blue disk galaxies, with optical and HI properties that are not unusual for their luminosity and morphology. We see evidence of both ongoing assembly, through the gas dynamics between interacting systems, and significant gas accretion, seen in extended gas disks and kinematic misalignments. The VGS establishes a local reference sample to be used in future HI surveys (CHILES, DINGO, LADUMA) that will directly observe the HI evolution of void galaxies over cosmic time.

  15. Collapse of elongated voids in porous energetic materials: Effects of void orientation and aspect ratio on initiation

    Science.gov (United States)

    Rai, Nirmal Kumar; Schmidt, Martin J.; Udaykumar, H. S.

    2017-04-01

    The sensitivity of porous energetic materials depends on mesostructural heterogeneities such as voids, defects, cracks, and grain boundaries. The mesostructure of pressed explosives contains voids of arbitrary shapes including elongated voids of various orientations and aspect ratios. Mesoscale simulations to date have analyzed the effect of void morphology on the sensitivity of energetic materials for idealized shapes such as cylindrical, conical, and elliptical. This work analyzes the sensitivity behavior of elongated voids in an HMX matrix subject to shock loading. Simulations show that sensitivity of elongated voids depends strongly on orientation as well as aspect ratio. Ranges of orientations and aspects ratios are identified that enhance or inhibit initiation. Insights obtained from single elongated void analyses are used to identify sensitive locations in an imaged mesostructure of a pressed explosive sample.

  16. Void fraction prediction in saturated flow boiling

    Energy Technology Data Exchange (ETDEWEB)

    Francisco J Collado [Dpto de Ingenieria Mecanica-Motores Termicos, CPS-B, Universidad de Zaragoza, Maria de Luna 50018-Zaragoza (Spain)

    2005-07-01

    Full text of publication follows: An essential element in thermal-hydraulics is the accurate prediction of the vapor void fraction, or fraction of the flow cross-sectional area occupied by steam. Recently, the author has suggested to calculate void fraction working exclusively with thermodynamic properties. It is well known that the usual 'flow' quality, merely a mass flow rate ratio, is not at all a thermodynamic property because its expression in function of thermodynamic properties includes the slip ratio, which is a parameter of the process not a function of state. By the other hand, in the classic and well known expression of the void fraction - in function of the true mass fraction of vapor (also called 'static' quality), and the vapor and liquid densities - does not appear the slip ratio. Of course, this would suggest a direct procedure for calculating the void fraction, provided we had an accurate value of the true mass fraction of vapor, clearly from the heat balance. However the classic heat balance is usually stated in function of the 'flow' quality, what sounds really contradictory because this parameter, as we have noted above, is not at all a thermodynamic property. Then we should check against real data the actual relationship between the thermodynamic properties and the applied heat. For saturated flow boiling just from the inlet of the heated tube, and not having into account the kinetic and potential terms, the uniform applied heat per unit mass of inlet water and per unit length (in short, specific linear heat) should be closely related to a (constant) slope of the mixture enthalpy. In this work, we have checked the relation between the specific linear heat and the thermodynamic enthalpy of the liquid-vapor mixture using the actual mass fraction. This true mass fraction is calculated using the accurate measurements of the outlet void fraction taken during the Cambridge project by Knights and Thom in the sixties for

  17. Grain boundary void nucleation in astroloy produced by room temperature deformation and anneal

    Science.gov (United States)

    Saegusa, T.; Uemura, M.; Weertman, J. R.

    1980-08-01

    Dyson and co-workers have shown that the creep life of a nickel base superalloy can be greatly shortened if the material is strained at room temperature before the creep test is carried out. They found that a prestrain followed by a short annealing time produces small grain boundary cavities, and it is the presence of these prenucleated voids which so seriously degrades service life at elevated temperatures. The present work explores the relationship between microstructure and prestrain void nucleation. Samples of the nickel base superalloy astroloy were given various heat treatments which led to significantly different microstructures. It was found that voids resulting from a prestrain-anneal treatment form preferentially at the ends of carbides on grain boundaries oriented roughly parallel to the prestrain tensile axis or rolling direction. Void spacing in the various microstructures is proportional to (but larger than) carbide spacing. The growth of these cavities during annealing is attributed to the presence of tensile residual stresses arising from the difference in deformability between grain boundary regions and the relatively soft matrix.

  18. The view from the boundary: a new void stacking method

    CERN Document Server

    Cautun, Marius; Frenk, Carlos S

    2015-01-01

    We introduce a new method for stacking voids and deriving their profile that greatly increases the potential of voids as a tool for precision cosmology. Given that voids are highly non-spherical and have most of their mass at their edge, voids are better described relative to their boundary rather than relative to their centre, as in the conventional spherical stacking approach. The boundary profile is obtained by computing the distance of each volume element from the void boundary. Voids can then be stacked and their profiles computed as a function of this boundary distance. This approach enhances the weak lensing signal of voids, both shear and convergence, by a factor of two when compared to the spherical stacking method. It also results in steeper void density profiles that are characterised by a very slow rise inside the void and a pronounced density ridge at the void boundary, in qualitative agreement with theoretical models of expanding spherical underdensities. The resulting boundary density profile i...

  19. Voids in Ly{\\alpha} Forest Tomographic Maps

    CERN Document Server

    Stark, Casey W; White, Martin; Lee, Khee-Gan

    2015-01-01

    We present a new method of finding cosmic voids using tomographic maps of Ly{\\alpha} forest flux. We identify cosmological voids with radii of 2 - 12 $h^{-1}$Mpc in a large N-body simulation at $z = 2.5$, and characterize the signal of the high-redshift voids in density and Ly{\\alpha} forest flux. The void properties are similar to what has been found at lower redshifts, but they are smaller and have steeper radial density profiles. Similarly to what has been found for low-redshift voids, the radial velocity profiles have little scatter and agree very well with the linear theory prediction. We run the same void finder on an ideal Ly{\\alpha} flux field and tomographic reconstructions at various spatial samplings. We compare the tomographic map void catalogs to the density void catalog and find good agreement even with modest-sized voids ($r > 6 \\, h^{-1}$Mpc). Using our simple void-finding method, the configuration of the ongoing CLAMATO survey covering 1 deg$^2$ would provide a sample of about 100 high-redshi...

  20. The sparkling Universe: the coherent motions of cosmic voids

    CERN Document Server

    Lambas, Diego G; Ceccarelli, Laura; Ruiz, Andrés N; Paz, Dante J; Maldonado, Victoria E; Luparello, Heliana E

    2015-01-01

    We compute the bulk motions of cosmic voids, using a $\\Lambda$CDM numerical simulation considering the mean velocities of the dark matter inside the void itself and that of the haloes in the surrounding shell. We find coincident values of these two measures in the range $\\sim$ 300-400 km/s, not far from the expected mean peculiar velocities of groups and galaxy clusters. When analysing the distribution of the pairwise relative velocities of voids, we find a remarkable bimodal behaviour consistent with an excess of both systematically approaching and receding voids. We determine that the origin of this bimodality resides in the void large scale environment, since once voids are classified into void-in-void (R-type) or void-in-cloud (S-type), R-types are found mutually receding away, while S-types approach each other. The magnitude of these systematic relative velocities account for more than 100 km/s, reaching large coherence lengths of up to 200 h$^{-1}$ Mpc . We have used samples of voids from the Sloan Digi...

  1. Effects of Voids on Concrete Tensile Fracturing: A Mesoscale Study

    Directory of Open Access Journals (Sweden)

    Lei Xu

    2017-01-01

    Full Text Available A two-dimensional mesoscale modeling framework, which considers concrete as a four-phase material including voids, is developed for studying the effects of voids on concrete tensile fracturing under the plane stress condition. Aggregate is assumed to behave elastically, while a continuum damaged plasticity model is employed to describe the mechanical behaviors of mortar and ITZ. The effects of voids on the fracture mechanism of concrete under uniaxial tension are first detailed, followed by an extensive investigation of the effects of void volume fraction on concrete tensile fracturing. It is found that both the prepeak and postpeak mesoscale cracking in concrete are highly affected by voids, and there is not a straightforward relation between void volume fraction and the postpeak behavior due to the randomness of void distribution. The fracture pattern of concrete specimen with voids is controlled by both the aggregate arrangement and the distribution of voids, and two types of failure modes are identified for concrete specimens under uniaxial tension. It is suggested that voids should be explicitly modeled for the accurate fracturing simulation of concrete on the mesoscale.

  2. Baryon effects on void statistics in the EAGLE simulation

    Science.gov (United States)

    Paillas, Enrique; Lagos, Claudia D. P.; Padilla, Nelson; Tissera, Patricia; Helly, John; Schaller, Matthieu

    2017-10-01

    Cosmic voids are promising tools for cosmological tests due to their sensitivity to dark energy, modified gravity and alternative cosmological scenarios. Most previous studies in the literature of void properties use cosmological N-body simulations of dark matter (DM) particles that ignore the potential effect of baryonic physics. Using a spherical underdensity finder, we analyse voids using the mass field and subhalo tracers in the Evolution and Assembly of Galaxies and their Environment (EAGLE) simulations, which follow the evolution of galaxies in a Λ cold dark matter universe with state-of-the-art subgrid models for baryonic processes in a (100 cMpc)3 volume. We study the effect of baryons on void statistics by comparing results with DM-only simulations that use the same initial conditions as EAGLE. When identifying voids in the mass field, we find that a DM-only simulation produces 24 per cent more voids than a hydrodynamical one due to the action of galaxy feedback polluting void regions with hot gas, specially for small voids with rvoid ≤ 10 Mpc. We find that the way in which galaxy tracers are selected has a strong impact on the inferred void properties. Voids identified using galaxies selected by their stellar mass are larger and have cuspier density profiles than those identified by galaxies selected by their total mass. Overall, baryons have minimal effects on void statistics, as void properties are well captured by DM-only simulations, but it is important to account for how galaxies populate DM haloes to estimate the observational effect of different cosmological models on the statistics of voids.

  3. Void-induced dissolution in molecular dynamics simulations of NaCl and water.

    Science.gov (United States)

    Bahadur, Ranjit; Russell, Lynn M; Alavi, Saman; Martin, Scot T; Buseck, Peter R

    2006-04-21

    To gain a better understanding of the interaction of water and NaCl at the surface during dissolution, we have used molecular dynamics to simulate the interface with two equal-sized slabs of solid NaCl and liquid water in contact. The introduction of voids in the bulk of the salt, as well as steps or pits on the surface of the NaCl slab results in a qualitative change of system structure, as defined by radial distribution functions (RDFs). As an example, the characteristic Na-Na RDF for the system changes from regularly spaced narrow peaks (corresponding to an ordered crystalline structure), to a broad primary and smaller secondary peak (corresponding to a disordered structure). The change is observed at computationally short time scales of 100 ps, in contrast with a much longer time scale of 1 mus expected for complete mixing in the absence of defects. The void fraction (which combines both bulk and surface defects) required to trigger dissolution varies between 15%-20% at 300 K and 1 atm, and has distinct characteristics for the physical breakdown of the crystal lattice. The void fraction required decreases with temperature. Sensitivity studies show a strong dependence of the critical void fraction on the quantity and distribution of voids on the surface, with systems containing a balanced number of surface defects and a rough surface showing a maximum tendency to dissolve. There is a moderate dependence on temperature, with a 5% decrease in required void fraction with a 100 K increase in temperature, and a weak dependence on water potential model used, with the SPC, SPC/E, TIP4P, and RPOL models giving qualitatively identical results. The results were insensitive to the total quantity of water available for dissolution and the duration of the simulation.

  4. Void-induced dissolution in molecular dynamics simulations of NaCl and water

    Science.gov (United States)

    Bahadur, Ranjit; Russell, Lynn M.; Alavi, Saman; Martin, Scot T.; Buseck, Peter R.

    2006-04-01

    To gain a better understanding of the interaction of water and NaCl at the surface during dissolution, we have used molecular dynamics to simulate the interface with two equal-sized slabs of solid NaCl and liquid water in contact. The introduction of voids in the bulk of the salt, as well as steps or pits on the surface of the NaCl slab results in a qualitative change of system structure, as defined by radial distribution functions (RDFs). As an example, the characteristic Na-Na RDF for the system changes from regularly spaced narrow peaks (corresponding to an ordered crystalline structure), to a broad primary and smaller secondary peak (corresponding to a disordered structure). The change is observed at computationally short time scales of 100ps, in contrast with a much longer time scale of 1μs expected for complete mixing in the absence of defects. The void fraction (which combines both bulk and surface defects) required to trigger dissolution varies between 15%-20% at 300K and 1atm, and has distinct characteristics for the physical breakdown of the crystal lattice. The void fraction required decreases with temperature. Sensitivity studies show a strong dependence of the critical void fraction on the quantity and distribution of voids on the surface, with systems containing a balanced number of surface defects and a rough surface showing a maximum tendency to dissolve. There is a moderate dependence on temperature, with a 5% decrease in required void fraction with a 100K increase in temperature, and a weak dependance on water potential model used, with the SPC, SPC/E, TIP4P, and RPOL models giving qualitatively identical results. The results were insensitive to the total quantity of water available for dissolution and the duration of the simulation.

  5. Filling the void - enriching the feature space of successful stopping

    NARCIS (Netherlands)

    Huster, René J.; Schneider, Signe; Lavallee, Christina F.; Enriquez-Geppert, Stefanie; Herrmann, Christoph S.

    2017-01-01

    The ability to inhibit behavior is crucial for adaptation in a fast changing environment and is commonly studied with the stop signal task. Current EEG research mainly focuses on the N200 and P300 ERPs and corresponding activity in the theta and delta frequency range, thereby leaving us with a

  6. Budgeting Academic Space

    Science.gov (United States)

    Harris, Watson

    2011-01-01

    There are many articles about space management, including those that discuss space calculations, metrics, and categories. Fewer articles discuss the space budgeting processes used by administrators to allocate space. The author attempts to fill this void by discussing her administrative experiences with Middle Tennessee State University's (MTSU)…

  7. The Void Galaxy Survey: Galaxy Evolution and Gas Accretion in Voids

    NARCIS (Netherlands)

    Kreckel, Kathryn; van Gorkom, Jacqueline H.; Beygu, Burcu; van de Weijgaert, Marinus; van der Hulst, J. M.; Aragon-Calvo, Miguel A.; Peletier, Reynier F.

    2014-01-01

    Voids represent a unique environment for the study of galaxy evolution, as the lower density environment is expected to result in shorter merger histories and slower evolution of galaxies. This provides an ideal opportunity to test theories of galaxy formation and evolution. Imaging of the neutral h

  8. The Void Galaxy Survey: Galaxy Evolution and Gas Accretion in Voids

    CERN Document Server

    Kreckel, Kathryn; Beygu, Burcu; van de Weygaert, Rien; van der Hulst, J M; Aragon-Calvo, Miguel A; Peletier, Reynier F

    2014-01-01

    Voids represent a unique environment for the study of galaxy evolution, as the lower density environment is expected to result in shorter merger histories and slower evolution of galaxies. This provides an ideal opportunity to test theories of galaxy formation and evolution. Imaging of the neutral hydrogen, central in both driving and regulating star formation, directly traces the gas reservoir and can reveal interactions and signs of cold gas accretion. For a new Void Galaxy Survey (VGS), we have carefully selected a sample of 59 galaxies that reside in the deepest underdensities of geometrically identified voids within the SDSS at distances of ~100 Mpc, and pursued deep UV, optical, Halpha, IR, and HI imaging to study in detail the morphology and kinematics of both the stellar and gaseous components. This sample allows us to not only examine the global statistical properties of void galaxies, but also to explore the details of the dynamical properties. We present an overview of the VGS, and highlight key re...

  9. The Void Galaxy Survey: Star Formation Properties

    CERN Document Server

    Beygu, B; van der Hulst, J M; Jarrett, T H; Peletier, R; van de Weygaert, R; van Gorkom, J H; Aragon-Calvo, M A

    2016-01-01

    We study the star formation properties of 59 void galaxies as part of the Void Galaxy Survey (VGS). Current star formation rates are derived from $\\rm{H\\alpha}$ and recent star formation rates from near-UV imaging. In addition, infrared 3.4 $\\rm{\\mu m}$, 4.6 $\\rm{\\mu m}$, 12 $\\rm{\\mu m}$ and 22 $\\rm{\\mu m}$ WISE emission is used as star formation and mass indicator. Infrared and optical colours show that the VGS sample displays a wide range of dust and metallicity properties. We combine these measurements with stellar and HI masses to measure the specific SFRs ($\\rm{SFR/M_{*}}$) and star formation efficiencies ($\\rm{SFR/M_{HI}}$). We compare the star formation properties of our sample with galaxies in the more moderate density regions of the cosmic web, 'the field'. We find that specific SFRs of the VGS galaxies as a function of stellar and HI mass are similar to those of the galaxies in these field regions. Their $\\rm{SFR\\alpha}$ is slightly elevated than the galaxies in the field for a given total HI mass. ...

  10. Ductile damage of porous materials with two populations of voids

    Science.gov (United States)

    Vincent, Pierre-Guy; Monerie, Yann; Suquet, Pierre

    2008-01-01

    This study is devoted to the modelling of ductile damage in uranium dioxide. This polycrystalline material contains two populations of voids of well separated size. The problem addressed here is the prediction of the effective flow surface of a Gurson material containing randomly oriented oblate voids. The case of spherical voids is considered first and the variational approach of Gurson is generalized by adding a compressible component to his original velocity field. The case of aligned oblate voids is then considered and a suitable generalization of a velocity field due to Gologanu et al. (ASME J. Engrg. Mater. Technol. 116 (1994) 290-297) is proposed. The extension to randomly oriented voids is achieved by averaging over all orientations. In each case, rigorous upper bounds and approximate estimates are derived and compared (in the case of spherical voids) with Finite Element simulations. To cite this article: P.-G. Vincent et al., C. R. Mecanique 336 (2008).

  11. Voids and the Cosmic Web: cosmic depressions & spatial complexity

    CERN Document Server

    van de Weygaert, Rien

    2016-01-01

    Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do they represent a key constituent of the Cosmic Web, they also are one of the cleanest probes and measures of global cosmological parameters. The shape and evolution of voids are highly sensitive to the nature of dark energy, while their substructure and galaxy population provides a direct key to the nature of dark matter. Also, the pristine environment of void interiors is an important testing ground for our understanding of environmental influences on galaxy formation and evolution. In this paper, we review the key aspects of the structure and dynamics of voids, with a particular focus on the hierarchical evolution of the void population. We demonstrate how the rich structural pattern of the Cosmic Web is related to the complex evolution and buildup of voids.

  12. Void alignment and density profile applied to measuring cosmological parameters

    CERN Document Server

    Dai, De-Chang

    2015-01-01

    We study the orientation and density profiles of the cosmological voids with SDSS10 data. Using voids to test Alcock-Paczynski effect has been proposed and tested in both simulations and actual SDSS data. Previous observations imply that there exist an empirical stretching factor which plays an important role in the voids' orientation. Simulations indicate that this empirical stretching factor is caused by the void galaxies' peculiar velocities. Recently Hamaus et al. found that voids' density profiles are universal and their average velocities satisfy linear theory very well. In this article we first confirm that the stretching effect exists using independent analysis. We then apply the universal density profile to measure the cosmological parameters. We find that the void density profile can be a tool to measure the cosmological parameters.

  13. Stokes-Brinkman formulation for prediction of void formation in dual-scale fibrous reinforcements: a BEM/DR-BEM simulation

    Science.gov (United States)

    Patiño, Iván David; Power, Henry; Nieto-Londoño, César; Flórez, Whady Felipe

    2017-02-01

    A numerical study of voids formation in dual-scale fibrous reinforcements is presented. Flow fields in channels (Stokes) and tows (Brinkman) are solved via direct Boundary Element Method and Dual Reciprocity Boundary Element Method, respectively. The present approach uses only boundary discretization and Dual Reciprocity domain interpolation, which is advantageous in this type of moving boundary problems and leads to an accurate representation of the moving interfaces. A problem admitting analytical solution, previously solved by domain-meshing techniques, is used to assess the accuracy of the present approach, obtaining satisfactory results. Fillings of Representative Unitary Cells at constant pressure are considered to analyze the influence of capillary ratio, jump stress coefficient and two formulations (Stokes-Brinkman and Stokes-Darcy) on the filling process, void formation and void characterization. Filling times, fluid front shapes, void size and shape, time and space evolution of the saturation, are influenced by these parameters, but voids location is not.

  14. LHC Create

    CERN Document Server

    CERN. Geneva

    2017-01-01

    LHC Create is an upcoming 2-day workshop held at IdeaSquare in November. Participants from CERN and IPAC school of design will compete to design an exhibit that explains why CERN does what it does. The winner will have their exhibit fully realised and made available to experiments, institutes, and tourism agencies around the world.

  15. An observational detection of the bridge effect of void filaments

    CERN Document Server

    Shim, Junsup; Hoyle, Fiona

    2015-01-01

    The bridge effect of void filaments is a phrase coined by Park & Lee (2009b) to explain the correlations found in a numerical experiment between the luminosity of the void galaxies and the degree of the straightness of their host filaments. Their numerical finding implies that a straight void filament provides a narrow channel for the efficient transportation of gas and matter particles from the surroundings into the void galaxies. To observationally confirm the presence of the bridge effect of void filaments, we identify the filamentary structures from the Sloan void catalog and determine the specific size of each void filament as a measure of its straightness. Using both classical and Bayesian statistics, we indeed detect a strong tendency that the void galaxies located in the more straight filaments are on average more luminous, which is in agreement with the numerical prediction. It is also shown that the strength of correlation increases with the spatial extent of the void filaments, which can be phy...

  16. The sparkling Universe: a scenario for cosmic void motions

    CERN Document Server

    Ceccarelli, Laura; Lares, Marcelo; Paz, Dante J; Maldonado, Victoria E; Luparello, Heliana E; Lambas, Diego Garcia

    2015-01-01

    We perform a statistical study of the global motion of cosmic voids using both a numerical simulation and observational data. We analyse their relation to large--scale mass flows and the physical effects that drive those motions. We analyse the bulk motions of voids, defined by the mean velocity of haloes in the surrounding shells in the numerical simulation, and by galaxies in the Sloan Digital Sky Survey Data Release 7. We find void mean bulk velocities close to 400 km/s, comparable to those of haloes (~ 500-600 km/s), depending on void size and the large--scale environment. Statistically, small voids move faster than large ones, and voids in relatively higher density environments have higher bulk velocities than those placed in large underdense regions. Also, we analyze the mean mass density around voids finding, as expected, large--scale overdensities (underdensities) along (opposite to) the void motion direction, suggesting that void motions respond to a pull--push mechanism. This contrasts with massive ...

  17. New Statistical Perspective to The Cosmic Void Distribution

    CERN Document Server

    Pycke, Jean-Renaud

    2016-01-01

    In this study, we obtain the size distribution of voids as a 3-parameter redshift independent log-normal void probability function (VPF) directly from the Cosmic Void Catalog (CVC). Although many statistical models of void distributions are based on the counts in randomly placed cells, the log-normal VPF that we here obtain is independent of the shape of the voids due to the parameter-free void finder of the CVC. We use three void populations drawn from the CVC generated by the Halo Occupation Distribution (HOD) Mocks which are tuned to three mock SDSS samples to investigate the void distribution statistically and the effects of the environments on the size distribution. As a result, it is shown that void size distributions obtained from the HOD Mock samples are satisfied by the 3-parameter log-normal distribution. In addition, we find that there may be a relation between hierarchical formation, skewness and kurtosis of the log-normal distribution for each catalog. We also show that the shape of the 3-paramet...

  18. Propagation of Love waves in an elastic layer with void pores

    Indian Academy of Sciences (India)

    S Dey; S Gupta; A K Gupta

    2004-08-01

    The paper presents a study of propagation of Love waves in a poroelastic layer resting over a poro-elastic half-space. Pores contain nothing of mechanical or energetic significance. The study reveals that such a medium transmits two types of love waves. The first front depends upon the modulus of rigidity of the elastic matrix of the medium and is the same as the love wave in an elastic layer over an elastic half-space. The second front depends upon the change in volume fraction of the pores. As the first front is well-known, the second front has been investigated numerically for different values of void parameters. It is observed that the second front is many times faster than the shear wave in the void medium due to change in volume fraction of the pores and is significant.

  19. A study of process induced voids in resistance welding of thermoplastic composites

    OpenAIRE

    Shi, H.; Fernandez Villegas, I.; Bersee, H.E.N.

    2015-01-01

    Void formation in resistance welding of woven fabric reinforced thermoplastic composites was investigated. Void contents were measured using optical microscopy and digital image process. Un-even void distributions were observed in the joints, and more voids were found in the middle of the joints than the edges. A higher welding pressure was shown to help reduce the void generation. The mechanisms of void formation, in particular fibre de-compaction induced voids and residual moisture induced ...

  20. Behaviour of voids in a shear field

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2009-01-01

    to a plane connecting the ends of the micro-crack is used as an approximate representation of contact stresses during frictionless sliding. In a previous study of the same problem the author applied hydrostatic pressure inside the nearly closed micro-crack to approximate contact conditions. The transverse...... surface loads used in the present analyses avoid the tendency to unrealistically elongate the voids. It is found that even though the model applied here gives significantly later occurrence of a maximum overall shear stress than that found by using hydrostatic pressure, the present model does predict...... a maximum in all the cases analyzed and thus illustrates the micro-mechanism leading to failure of the material by localization of plastic flow....

  1. Formation of Voids from Negative Density Perturbations

    Science.gov (United States)

    de Araujo, J. C. N.; Opher, R.

    1990-11-01

    RESUMEN. Se estudia la formaci6n de huecos a partir de un espectro negativo de perturbaciones, tomando en cuenta la expansi6n del Universo, arrastre por fotones, enfriamiento por fotones, fotoionizaci6n, ioniza- ci6n colisional, enfriamiento Lyman a y la formaci6n y enfriamiento de moleculas H2. Nuestros resultados predicen la existencia de regiones 1/10 de Ia densidad promedio para regiones de masa lO - 1O10M . ABSTRACT. In the present paer we study the formation of voids from a negative spectrum of perturbations taking into account the expansion of the Universe, photon-drag, photon-cooling, photoionization, collisional ionization, Lyman a cooling and the formation and cooling of 112 molecules. Our results predict the existence of regions 1/10 the average density for regions of mass 1O - 1O10M@ : CLUSTERS-GALAXIES - COSMOLOGY

  2. The VIMOS Public Extragalactic Redshift Survey: Measuring the growth rate of structure around cosmic voids

    CERN Document Server

    Hawken, A J; Iovino, A; Guzzo, L; Peacock, J A; de la Torre, S; Garilli, B; Bolzonella, M; Scodeggio, M; Abbas, U; Adami, C; Bottini, D; Cappi, A; Cucciati, O; Davidzon, I; Fritz, A; Franzetti, P; Krywult, J; Brun, V Le; Fevre, O Le; Maccagni, D; Małek, K; Marulli, F; Polletta, M; Pollo, A; Tasca, L A M; Tojeiro, R; Vergani, D; Zanichelli, A; Arnouts, S; Bel, J; Branchini, E; De Lucia, G; Ilbert, O; Moscardini, L; Percival, W J

    2016-01-01

    We identified voids in the completed VIMOS Public Extragalactic Redshift Survey (VIPERS), using an algorithm based on searching for empty spheres. We measured the cross-correlation between the centres of voids and the complete galaxy catalogue. The cross-correlation function exhibits a clear anisotropy in both VIPERS fields (W1 and W4), which is characteristic of linear redshift space distortions. By measuring the projected cross-correlation and then deprojecting it we are able to estimate the undistorted cross-correlation function. We propose that given a sufficiently well measured cross-correlation function one should be able to measure the linear growth rate of structure by applying a simple linear Gaussian streaming model for the redshift space distortions (RSD). Our study of voids in 306 mock galaxy catalogues mimicking the VIPERS fields would suggest that VIPERS is capable of measuring $\\beta$ with an error of around $25\\%$. Applying our method to the VIPERS data, we find a value for the redshift space ...

  3. Measuring the growth rate of structure around cosmic voids

    Science.gov (United States)

    Hawken, A. J.; Michelett, D.; Granett, B.; Iovino, A.; Guzzo, L.

    2016-10-01

    Using an algorithm based on searching for empty spheres we identified 245 voids in the VIMOS Public Extragalactic Redshift Survey (VIPERS). We show how by modelling the anisotropic void-galaxy cross correlation function we can probe the growth rate of structure.

  4. An Interacting Galaxy System along a Filament in a Void

    NARCIS (Netherlands)

    Beygu, B.; Kreckel, K.; van de Weijgaert, R.; van der Hulst, J. M.; van Gorkom, J. H.

    2013-01-01

    Cosmological voids provide a unique environment for the study of galaxy formation and evolution. The galaxy population in their interiors has properties significantly different from average field galaxies. As part of our Void Galaxy Survey (VGS), we have found a system of three interacting galaxies

  5. A Cosmic Void Catalog of SDSS DR12 BOSS Galaxies

    CERN Document Server

    Mao, Qingqing; Scherrer, Robert J; Scoccimarro, Roman; Tinker, Jeremy L; McBride, Cameron K; Neyrinck, Mark C; Schneider, Donald P; Pan, Kaike; Bizyaev, Dmitry; Malanushenko, Elena; Malanushenko, Viktor

    2016-01-01

    We present a cosmic void catalog using the large-scale structure galaxy catalog from the Baryon Oscillation Spectroscopic Survey (BOSS). This galaxy catalog is part of the Sloan Digital Sky Survey (SDSS) Data Release 12 and is the final catalog of SDSS-III. We take into account the survey boundaries, masks, and angular and radial selection functions, and apply the ZOBOV void finding algorithm to the galaxy catalog. After making quality cuts to ensure that the voids represent real underdense regions, we identify 1228 voids with effective radii spanning the range 20-100Mpc/h and with central densities that are, on average, 30% of the mean sample density. We discuss the basic statistics of voids, such as their size and redshift distributions, and measure the radial density profile of the voids via a stacking technique. In addition, we construct mock void catalogs from 1000 mock galaxy catalogs, and find that the properties of BOSS voids are in good agreement with those in the mock catalogs. We compare the stella...

  6. Tensor anisotropy as a tracer of cosmic voids

    CERN Document Server

    Bustamante, Sebastian

    2015-01-01

    We present a new method to find voids in cosmological simulations based on the tidal and the velocity shear tensors definitions of the cosmic web. We use the fractional anisotropy (FA) computed from the eigenvalues of each web scheme as a void tracer. We identify voids using a watershed transform based on the local minima of the FA field without making any assumption on the shape or structure of the voids. We test the method on the Bolshoi simulation and report on the abundance and radial averaged profiles for the density, velocity and fractional anisotropy. We find that voids in the velocity shear web are smaller than voids in the tidal web, with a particular overabundance of very small voids in the inner region of filaments/sheets. We classify voids as subcompensated/overcompansated depending on the absence/presence of an overdense matter ridge in their density profile, finding that close to $65\\%$ and $35\\%$ of the total population are classified into each category, respectively. Finally, we find evidence ...

  7. The relationship between void waves and flow regime transition

    Energy Technology Data Exchange (ETDEWEB)

    Lahey, R.T. Jr.; Drew, D.A.; Kalkach-Navarro, S.; Park, J.W.

    1992-12-31

    The results of an extensive experimental and analytical study on the relationship between void waves and flow regime transition are presented, in particular, the bubbly/slug flow regime transition. It is shown that void wave instability signals a flow regime transition.

  8. Voided stain on paper method for analysis of mouse urination.

    Science.gov (United States)

    Sugino, Y; Kanematsu, A; Hayashi, Y; Haga, H; Yoshimura, N; Yoshimura, K; Ogawa, O

    2008-01-01

    To evaluate the usefulness of a quantification method using filter paper for analyzing minute voided urine of the mouse. Voided stain on paper (VSOP) method; the correlation between area of stained spot on a filter paper and amount of applied liquid was calculated. Voiding behavior of the mice was analyzed by placing the animal above the same filter paper and recording voided time and area over 2 hr. The usefulness of the VSOP method was tested in analysis of the voiding behavior of five female 7-week-old ddY mice treated with cyclophosphamide (CPM, 150 mg/kg, intraperitoneally) and five control ones, in comparison with the histology of CPM-induced cystitis. Further, the voided volume of male and female ddY mouse ranging from 2 to 13 weeks was assessed. There was a linear correlation between liquid volume and stained area on the filter paper (y = 16.472x - 22.411, R(2) = 0.9981). Between control mice and those with histologically proven CPM cystitis, there was a significant difference in voided volume (362.7 +/- 51.9 and 127.8 +/- 100.0 microl, VSOP method is a useful tool for evaluating voiding behavior of the mouse, including those with small bladder capacity.

  9. Voids and the Cosmic Web: cosmic depression & spatial complexity

    NARCIS (Netherlands)

    van de Weygaert, Rien; Shandarin, S.; Saar, E.; Einasto, J.

    2016-01-01

    Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do theyrepresent a key constituent of the Cosmic Web, they also are one of the cleanest probesand measures of global cosmological parameters. The shape and evolution of voids are highly sensitive tothe natu

  10. High gain durable anti-reflective coating with oblate voids

    Energy Technology Data Exchange (ETDEWEB)

    Maghsoodi, Sina; Brophy, Brenor L.; Colson, Thomas E.; Gonsalves, Peter R.; Abrams, Ze' ev

    2016-06-28

    Disclosed herein are single layer transparent coatings with an anti-reflective property, a hydrophobic property, and that are highly abrasion resistant. The single layer transparent coatings contain a plurality of oblate voids. At least 1% of the oblate voids are open to a surface of the single layer transparent coatings.

  11. The Aspen-Amsterdam void finder comparison project

    NARCIS (Netherlands)

    Colberg, Joerg M.; Pearce, Frazer; Foster, Caroline; Platen, Erwin; Brunino, Riccardo; Neyrinck, Mark; Basilakos, Spyros; Fairall, Anthony; Feldman, Hume; Gottloeber, Stefan; Hahn, Oliver; Hoyle, Fiona; Mueller, Volker; Nelson, Lorne; Plionis, Manolis; Porciani, Cristiano; Shandarin, Sergei; Vogeley, Michael S.; van de Weygaert, Rien

    2008-01-01

    Despite a history that dates back at least a quarter of a century, studies of voids in the large-scale structure of the Universe are bedevilled by a major problem: there exist a large number of quite different void-finding algorithms, a fact that has so far got in the way of groups comparing their

  12. Locating voids beneath pavement using pulsed electromagnetic waves

    Science.gov (United States)

    Steinway, W. J.; Echard, J. D.; Luke, C. M.

    1981-11-01

    The feasibility of using pulsed electromagnetic wave technology for locating and sizing voids beneath reinforced and nonreinforced portland cement concrete pavements is determined. The data processing techniques developed can be implemented to provide information for void depth and sizing to + or - 1/2 in. and spatial location within + or - 6 in. A very short pulse radar directly connected to a microcomputer was chosen as the equipment necessary to obtain measurements. This equipment has the required accuracy and reliability, and is a cost effective solution for the void locating problem. The radar provides a signal return from voids that has unique characteristics that can be examined to provide information regarding the location, depth, and shape of the void. The microcomputer provides a means of real time processing to extract the information from the radar signal return and record the results. Theoretical modeling of signal returns from voids led to suitable techniques for locating and sizing voids beneath the pavement. Analysis and application of these techniques to radar measurements verified the theoretical predictions that radar can be used to determine the location, size, and shape of actual voids.

  13. Warmth Elevating the Depths: Shallower Voids with Warm Dark Matter

    CERN Document Server

    Yang, Lin F; Aragon-Calvo, Miguel A; Silk, Joseph

    2014-01-01

    Warm dark matter (WDM) has been proposed as an alternative to cold dark matter (CDM), to resolve issues such as the apparent lack of satellites around the Milky Way. Even if WDM is not the answer to observational issues, it is essential to constrain the nature of the dark matter. The effect of WDM on haloes has been extensively studied, but the small-scale initial smoothing in WDM also affects the present-day cosmic web and voids. It suppresses the cosmic "sub-web" inside voids, and the formation of both void haloes and subvoids. In N-body simulations run with different assumed WDM masses, we identify voids with the zobov algorithm, and cosmic-web components with the origami algorithm. As dark-matter warmth increases, the initial-conditions smoothing increases, and the number of voids and subvoids is suppressed. Also, void density profiles change, their shapes become flatter inside the void radius, while edges of the voids remain unchanged. Also, filaments and walls become cleaner, as the sub-structures in be...

  14. Dislocation and void segregation in copper during neutron irradiation

    DEFF Research Database (Denmark)

    Singh, Bachu Narain; Leffers, Torben; Horsewell, Andy

    1986-01-01

    High-purity (99. 999%) and fully annealed copper specimens have been irradiated in the DR-3 reactor at Riso to doses of 1 multiplied by 10**2**2 and 5 multiplied by 10**2**2 neutrons (fast)m** minus **2(2 multiplied by 10** minus **3 dpa and 1 multiplied by 10** minus **2 dpa, respectively...... were distributed between these walls. The dislocation walls were practically free of voids and generally had a void-denuded zone along them. The density of dislocations (loops and segments) was very low in the region containing voids (i. e. between the dislocation walls). Even with this low dislocation...... density, the void swelling rate was very high (approximately 2. 5% per dpa). The implications of the segregated distribution of sinks for void formation and growth are briefly discussed....

  15. Alignment of galaxy spins in the vicinity of voids

    CERN Document Server

    Slosar, Anze

    2008-01-01

    We provide limits on the alignment of galaxy orientations with the direction to the void center for galaxies lying near the edges of voids. We locate spherical voids in volume limited samples of galaxies from the Sloan Digital Sky Survey using the HB inspired void finder and investigate the orientation of (color selected) spiral galaxies that are nearly edge-on or face-on. In contrast with previous literature, we find no statistical evidence for departure from random orientations. Expressed in terms of the parameter c, introduced by Lee & Pen to describe the strength of such an alignment, we find that c<0.11(0.13) at 95% (99.7%) confidence limit within a context of a toy model that assumes a perfectly spherical voids with sharp boundaries.

  16. Two new methods to detect cosmic voids without density measurements

    CERN Document Server

    Elyiv, Andrii; Pollina, Giorgia; Baldi, Marco; Branchini, Enzo; Cimatti, Andrea; Moscardini, Lauro

    2014-01-01

    Cosmic voids are effective cosmological probes to discriminate among competing world models. Their precise and unbiased identification is a prerequisite to perform accurate observational tests. The identification is generally based on density or geometry criteria that, because of their very nature, are prone to shot noise errors. In this work we propose two new void finders that are based on dynamical and clustering criteria to select voids in the Lagrangian coordinates and minimise the impact of sparse sampling. The first approach exploits the Zeldovich approximation to trace back in time the orbits of galaxies located in the voids and their surroundings, whereas the second uses the observed galaxy-galaxy correlation function to relax the objects' spatial distribution to homogeneity and isotropy. In both cases voids are defined as regions of the negative velocity divergence in Lagrangian coordinates, that can be regarded as sinks of the back-in-time streamlines of the mass tracers. To assess the performance ...

  17. The cosmic web in CosmoGrid void regions

    Science.gov (United States)

    Rieder, Steven; van de Weygaert, Rien; Cautun, Marius; Beygu, Burcu; Portegies Zwart, Simon

    2016-10-01

    We study the formation and evolution of the cosmic web, using the high-resolution CosmoGrid ΛCDM simulation. In particular, we investigate the evolution of the large-scale structure around void halo groups, and compare this to observations of the VGS-31 galaxy group, which consists of three interacting galaxies inside a large void. The structure around such haloes shows a great deal of tenuous structure, with most of such systems being embedded in intra-void filaments and walls. We use the Nexus+} algorithm to detect walls and filaments in CosmoGrid, and find them to be present and detectable at every scale. The void regions embed tenuous walls, which in turn embed tenuous filaments. We hypothesize that the void galaxy group of VGS-31 formed in such an environment.

  18. Voids and the Cosmic Web: cosmic depression & spatial complexity

    Science.gov (United States)

    van de Weygaert, Rien

    2016-10-01

    Voids form a prominent aspect of the Megaparsec distribution of galaxies and matter. Not only do theyrepresent a key constituent of the Cosmic Web, they also are one of the cleanest probesand measures of global cosmological parameters. The shape and evolution of voids are highly sensitive tothe nature of dark energy, while their substructure and galaxy population provides a direct key to thenature of dark matter. Also, the pristine environment of void interiors is an important testing groundfor our understanding of environmental influences on galaxy formation and evolution. In this paper, we reviewthe key aspects of the structure and dynamics ofvoids, with a particular focus on the hierarchical evolution of the void population. We demonstratehow the rich structural pattern of the Cosmic Web is related to the complex evolution and buildupof voids.

  19. Experimental Study on Voided Reinforced Concrete Beams with Polythene Balls

    Science.gov (United States)

    Sivaneshan, P.; Harishankar, S.

    2017-07-01

    The primary component in any structure is concrete, that exist in buildings and bridges. In present situation, a serious problems faced by construction industry is exhaustive use of raw materials. Recent times, various methods are being adopted to limit the use of concrete. In structural elements like beams, polythene balls can be induced to reduce the usage of concrete. A simply supported reinforced concrete beam has two zones, one above neutral axis and other below neutral axis. The region below neutral axis is in tension and above neutral axis is in compression. As concrete is weak in tension, steel reinforcements are provided in tension zone. The concrete below the neutral axis acts as a stress transfer medium between the compression zone and tension zone. The concrete above the neutral axis takes minimum stress so that we could partially replace the concrete above neutral axis by creating air voids using recycled polythene balls. Polythene balls of varying diameters of 75 mm, 65 mm and 35 mm were partially replaced in compression zone. Hence the usage of concrete in beams and self-weight of the beams got reduced considerably. The Load carrying capacity, Deflection of beams and crack patterns were studied and compared with conventional reinforced concrete beams.

  20. Properties of hydrogen induced voids in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Weber, J; Fischer, T; Hieckmann, E; Hiller, M; Lavrov, E V [Institute for Applied Physics/Semiconductor Physics, TU Dresden, 01062 Dresden (Germany)

    2005-06-08

    After heat treatment, silicon samples implanted with high doses of hydrogen exhibit blistering and defoliation of thin silicon layers. The process is used commercially in the fabrication of thin silicon-on-insulator layers (Smart Cut(registered)). In the present study we investigate the behaviour of hydrogen after different processing steps, which lead to thin Si layers bonded to glass substrates. A set of hydrogen implanted samples is studied by means of low temperature photoluminescence, Raman spectroscopy, x-ray diffraction and optical microscopy (visible and infrared). The formation of Si-H bonds is detected after implantation together with a build-up of internal strain. After annealing, the relaxation of the implanted layers is found to be connected with the formation of hydrogen saturated vacancies and the formation of H{sub 2} molecules filling up larger voids. A comparison is made with hydrogen plasma treated samples, where well defined platelets on {l_brace}111{r_brace} planes are found to trap hydrogen molecules. No direct evidence of the role of {l_brace}111{r_brace} and {l_brace}100{r_brace} platelets in the blistering process is found in the implanted layers from our study. We determine considerable compressive stresses in the bonded Si layers on glass substrates. The photoluminescence is strongly enhanced in these bonded layers but red-shifted due to a strain reduced band gap.

  1. Radionuclide voiding cystography in intrarenal reflux detection

    Energy Technology Data Exchange (ETDEWEB)

    Rizzoni, G.; Perale, R.; Bui, F.; Pitter, M.; Pavanello, L.; Boscolo, R.; Passerini Glazel, G.; Macri, C.

    1986-01-01

    In order to evaluate the possibility of detecting intra-renal reflux (IRR) with a more sensitive procedure, 48 children with recurrent urinary tract infections underwent intravenous urography (IVU) and voiding cystourethrogram (VCU) using a solution containing contrast medium and sup(99m)Tc-sulfur colloid particles which are known to persist in the renal parenchyma for a long time. Scintigraphic images were taken at 5 and 20 hours after VCU. 18 children had no vesico-ureteral reflux, 11 showed unilateral and 19 bilateral VUR, which was therefore present in 49 renal units. Among the 49 renal refluxing units (RRUs) IRR was detected radiologically in 8; of these isotopic activity in the renal area was present in all 6 RRUs who were examined at 20 hours. Of the remaining 41 RRUs with no radiologically detectable IRR 24 were evaluated at 20 hours and 5 (21%) showed renal radioactivity. Renal scars were significantly more frequent in kidneys with radioisotopic activity at 20 hours. The results of this study indicate that radionuclide cystography using sup(99m)Tc-sulfur colloid is a reliable procedure for demonstrating IRR, and to this end is more sensitive than X-ray VCU. Radionuclide cystography with sulfur colloid particles should therefore be considered a simple and useful complementary procedure, which is more sensitive than X-ray VCU in the diagnosis and follow-up of IRR.

  2. Towards a better understanding of dielectric barrier discharges in ferroelectrets: Paschen breakdown fields in micrometer sized voids

    Science.gov (United States)

    Harris, Scott; Mellinger, Axel

    2014-04-01

    Charged cellular polypropylene foams (i.e., ferro- or piezoelectrets) demonstrate high piezoelectric activity upon being electrically charged. When an external electric field is applied, dielectric barrier discharges (DBDs) occur, resulting in a separation of charges which are subsequently deposited on dielectric surfaces of internal micrometer sized voids. This deposited space charge is responsible for the piezoelectric activity of the material. Previous studies have indicated charging fields larger than predicted by Townsend's model of Paschen breakdown applied to a multilayered electromechanical model; a discrepancy which prompted the present study. The actual breakdown fields for micrometer sized voids were determined by constructing single cell voids using polypropylene spacers with heights ranging from 8 to 75 μm, "sandwiched" between two polypropylene dielectric barriers and glass slides with semi-transparent electrodes. Subsequently, a bipolar triangular charging waveform with a peak voltage of 6 kV was applied to the samples. The breakdown fields were determined by monitoring the emission of light due to the onset of DBDs using an electron multiplying CCD camera. The breakdown fields at absolute pressures from 101 to 251 kPa were found to be in good agreement with the standard Paschen curves. Additionally, the magnitude of the light emission was found to scale linearly with the amount of gas, i.e., the height of the voids. Emissions were homogeneous over the observed regions of the voids for voids with heights of 25 μm or less and increasingly inhomogeneous for void heights greater than 40 μm at high electric fields.

  3. Partial discharges within two spherical voids in an epoxy resin

    Science.gov (United States)

    Illias, H. A.; Chen, G.; Bakar, A. H. A.; Mokhlis, H.; Tunio, M. A.

    2013-08-01

    A void in a dielectric insulation material may exist due to imperfection in the insulation manufacturing or long term stressing. Voids have been identified as one of the common sources of partial discharge (PD) activity within an insulation system, such as in cable insulation and power transformers. Therefore, it is important to study PD phenomenon within void cavities in insulation. In this work, a model of PD activity within two spherical voids in a homogeneous dielectric material has been developed using finite element analysis software to study the parameters affecting PD behaviour. The parameters that have been taken into account are the void surface conductivity, electron generation rate and the inception and extinction fields. Measurements of PD activity within two spherical voids in an epoxy resin under ac sinusoidal applied voltage have also been performed. The simulation results have been compared with the measurement data to validate the model and to identify the parameters affecting PD behaviour. Comparison between measurements of PD activity within single and two voids in a dielectric material have also been made to observe the difference of the results under both conditions.

  4. Measuring Baryon Acoustic Oscillations from the clustering of voids

    CERN Document Server

    Liang, Yu; Chuang, Chia-Hsun; Kitaura, Francisco-Shu; Tao, Charling

    2015-01-01

    We investigate the necessary methodology to optimally measure the baryon acoustic oscillation (BAO) signal, from voids based on galaxy redshift catalogues. To this end, we study the dependency of the BAO signal on the population of voids classified by their sizes. We find for the first time the characteristic features of the correlation function of voids including the first robust detection of BAOs in mock galaxy catalogues. These show an anti-correlation around the scale corresponding to the smallest size of voids in the sample (the void exclusion effect), and dips at both sides of the BAO peak, which can be used to determine the significance of the BAO signal without any priori model. Furthermore, our analysis demonstrates that there is a scale dependent bias for different populations of voids depending on the radius, with the peculiar property that the void population with the largest BAO significance corresponds to tracers with approximately zero bias on the largest scales. We further investigate the meth...

  5. Baryon effects on void statistics in the EAGLE simulation

    CERN Document Server

    Paillas, Enrique; Padilla, Nelson; Tissera, Patricia; Helly, John; Schaller, Matthieu

    2016-01-01

    Cosmic voids are promising tools for cosmological tests due to their sensitivity to dark energy, modified gravity and alternative cosmological scenarios. Most previous studies in the literature of void properties use cosmological N-body simulations of dark matter (DM) particles that ignore the potential effect of baryonic physics. We analyse voids in the mass and subhalo density field in the EAGLE simulations, which follow the evolution of galaxies in a Lambda cold dark matter Universe with state-of-the-art subgrid models for baryonic processes. We study the effect of baryons on void statistics by comparing results with simulations that only follow the evolution of DM, but use the same initial conditions as EAGLE. When using the mass in the simulation, we find that a DM-only simulation produces 24 per cent more voids than a hydrodynamical one, but this difference comes mainly from voids with radii smaller than 5 Mpc. We do not find significant differences in the density profiles between voids in EAGLE and its...

  6. The catalytic diversity of zeolites: confinement and solvation effects within voids of molecular dimensions.

    Science.gov (United States)

    Gounder, Rajamani; Iglesia, Enrique

    2013-05-01

    chemical composition, thus enabling voids of a given size and shape to provide the "right fit" for a given elementary step, defined as that which minimizes Gibbs free energies of activation. Tighter confinement is preferred at low temperatures because enthalpic gains prevail over concomitant entropic losses, while looser fits are favored at high temperatures because entropy gains offset losses in enthalpic stabilization. Confinement and solvation by van der Waals forces are not directly involved in the making or breaking of strong chemical bonds; yet, they confer remarkable diversity to zeolites, in spite of their structural rigidity and their common aluminosilicate composition. A single zeolite can itself contain a range of local void environments, each with distinct reactivity and selectivity; as a result, varying the distribution of protons among these locations within a given framework or modifying a given location by partial occlusion of the void space can extend the range of catalytic opportunities for zeolites. Taken together with theoretical tools that accurately describe van der Waals interactions between zeolite voids and confined guests and with synthetic protocols that place protons or space-filling moieties at specific locations, these concepts promise to broaden the significant impact and catalytic diversity already shown by microporous solids.

  7. Decay of charge deposited on the wall of gaseous void

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1992-01-01

    After partial discharge activity within a gaseous void, charges accumulate on the wall of the void. The decay of such charges due to surface currents at the void wall is studied analytically, and the factors affecting this decay are indicated. The results show that in terms of the basic time...... constant, the decay can take a considerable amount of time. The decay rate is significantly reduced by an increase in the permittivity of the bulk medium. The dominating influence of this permittivity is likewise reflected in the increased duration and thereby prolonged inhomogeneity of the electric field...

  8. A variational void coalescence model for ductile metals

    KAUST Repository

    Siddiq, Amir

    2011-08-17

    We present a variational void coalescence model that includes all the essential ingredients of failure in ductile porous metals. The model is an extension of the variational void growth model by Weinberg et al. (Comput Mech 37:142-152, 2006). The extended model contains all the deformation phases in ductile porous materials, i.e. elastic deformation, plastic deformation including deviatoric and volumetric (void growth) plasticity followed by damage initiation and evolution due to void coalescence. Parametric studies have been performed to assess the model\\'s dependence on the different input parameters. The model is then validated against uniaxial loading experiments for different materials. We finally show the model\\'s ability to predict the damage mechanisms and fracture surface profile of a notched round bar under tension as observed in experiments. © Springer-Verlag 2011.

  9. Void formation in ODS EUROFER produced by hot isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Y. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)], E-mail: yanicet@fis.ucm.es; Monge, M.A. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain); Castro, V. de [Department of Materials, University of Oxford, Oxford OX1 3PH (United Kingdom); Munoz, A.; Leguey, T.; Pareja, R. [Departamento de Fisica, Universidad Carlos III de Madrid, 28911 Leganes (Spain)

    2009-04-30

    Positron annihilation experiments were performed on oxide dispersion strengthened (ODS) and non-ODS EUROFER prepared by mechanical alloying and hot isostatic pressing. The results revealed the presence of small voids in these materials in the as-HIPed conditions. Their evolution under isochronal annealing experiments was investigated. The coincidence Doppler broadening spectra of ODS EUROFER exhibited a characteristic signature attributed to positron annihilation in Ar-decorated voids at the oxide particle/matrix interfaces. The variation of the positron annihilation parameters with the annealing temperature showed three stages: up to 623 K, between 823 and 1323 K, and above 1323 K. In the temperature range 823-1323 K void coarsening had effect. Above 1323 K some voids annealed out, but others, associated to oxide particles and small precipitates, survived to annealing at 1523 K. Transmission electron microscopy observations were also performed to verify the characteristics of the surviving defects after annealing at 1523 K.

  10. Evolution of shock through a void in foam

    Science.gov (United States)

    Kim, Y.; Smidt, J. M.; Murphy, T. J.; Douglass, M. R.; Devolder, B. G.; Fincke, J. R.; Schmidt, D. W.; Cardenas, T.; Newman, S. G.; Hamilton, C. E.; Sedillo, T. J.; Los Alamos, NM 87544 Team

    2016-10-01

    Marble implosion is an experimental campaign intended to study the effects of heterogeneous mix on fusion burn. A spherical capsule is composed of deuterated plastic foam of controlled pore (or void) size with tritium fill in pores. As capsule implosion evolves, the initially separated deuterium and tritium will mix, producing DT yields. Void evolution during implosion is of interest for the Marble campaign. A shock tube, driven by the laser at Omega, was designed to study the evolution of a shock through a foam-filled ``void'' and subsequent void evolution. Targets were comprised of a 100 mg/cc CH foam tube containing a 200-µm diameter, lower density doped foam sphere. High-quality, radiographic images were obtained from both 2% iodine-doped in plastic foam and 15% tin-doped in aerogel foam. These experiments will be used to inform simulations.

  11. Measurement and Analysis of Sodium Void Reactivity Effect in CEFR

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The sodium void reactivity effect (SVRE) is one of the important parameters in the design and safety analysis of sodium-cooled fast reactors. In some serious accident conditions, for example the total instantaneous blockage (TIB) accident,

  12. Uroflowmetry in neurologically normal children with voiding disorders

    DEFF Research Database (Denmark)

    Jensen, K M; Nielsen, K.K.; Kristensen, E S

    1985-01-01

    of neurological deficits underwent a complete diagnostic program including intravenous urography, voiding cystography and cystoscopy as well as spontaneous uroflowmetry, cystometry-emg and pressure-flow-emg study. The incidence of dyssynergia was 22%. However, neither the flow curve pattern nor single flow...... variables were able to identify children with dyssynergia. Consequently uroflowmetry seems inefficient in the screening for dyssynergia in neurological normal children with voiding disorders in the absence of anatomical bladder outlet obstruction....

  13. Void Growth in Single and Bicrystalline Metals: Atomistic Calculations

    Science.gov (United States)

    Traiviratana, Sirirat; Bringa, Eduardo M.; Benson, David J.; Meyers, Marc A.

    2007-12-01

    MD simulations in monocrystalline and bicrystalline copper were carried out with LAMMPS to reveal void growth mechanisms. The specimens were subjected to both tensile uniaxial and hydrostatic strains; the results confirm that the emission of (shear) loops is the primary mechanism of void growth. However, these shear loops develop along two slip planes (and not one, as previously thought), in a heretofore unidentified mechanism of cooperative growth. The emission of dislocations from voids is the first stage, and their reaction and interaction is the second stage. These loops, forming initially on different {111} planes, join at the intersection, the Burgers vector of the dislocations being parallel to the intersection of two {111} planes: a direction. Thus, the two dislocations cancel at the intersection and a biplanar shear loop is formed. The expansion of the loops and their cross slip leads to the severely work hardened layer surrounding a growing void. Calculations were carried out on voids with different sizes, and a size dependence of the stress response to emitted dislocations was observed, in disagreement with the Gurson model[1] which is scale independent. Calculations were also carried out for a void at the interface between two grains.

  14. Low and High Surface Brightness Galaxies at Void Walls

    CERN Document Server

    Ceccarelli, L; Lambas, D G; Galaz, G; Padilla, N D

    2012-01-01

    We study the relative fraction of low and high surface brightness galaxies (LSBGs and HSBGs) at void walls in the SDSS DR7. We focus on galaxies in equal local density environments. We assume that the host dark-matter halo mass (for which we use SDSS group masses) is a good indicator of local density. This analysis allows to examine the behavior of the abundance of LSBG and HSBG galaxies at a fixed local density and distinguish the large-scale environment defined by the void geometry. We compare galaxies in the field, and in the void walls; the latter are defined as the volume of void shells of radius equal to that of the void. We find a significant decrement, a factor $\\sim 4$, of the relative fraction of blue, active star-forming LSBGs in equal mass groups at the void walls and the field. This decrement is consistent with an increase of the fraction of blue, active star-forming HSBGs. By contrast, red LSBGs and HSBGs show negligible changes. We argue that these results are consistent with a scenario where L...

  15. The Effect of Nearby Voids on Galaxy Number Counts

    CERN Document Server

    Bucklein, Brian K; Hintz, Eric G

    2016-01-01

    The size, shape and degree of emptiness of void interiors sheds light on the details of galaxy formation. A particularly interesting question is whether void interiors are completely empty or contain a dwarf population. However the nearby voids that are most conducive for dwarf searches have large angular diameters, on the order of a steradian, making it difficult to redshift-map a statistically significant portion of their volume to the magnitude limit of dwarf galaxies. As part of addressing this problem, we investigate here the usefulness of number counts in establishing the best locations to search inside nearby (d < 300 Mpc) galaxy voids, utilizing Wolf plots of log(n < m) vs. m as the basic diagnostic. To illustrate expected signatures, we consider the signature of three void profiles, "cut out", "built up", and "universal profile" carved into Monte-Carlo Schechter function models. We then investigate the signatures of voids in the Millennium Run dark matter simulation and the Sloan Digital Sky Su...

  16. ACK filling void first algorithm and performance for asynchronous OPS

    Science.gov (United States)

    Liu, Huanlin; Shi, Yonghe; Chen, Qianbin; Pan, Yingjun

    2007-11-01

    OPS with feedback shared FDL buffer produce large voids due to FDL buffers only supplying discrete step delay and causing FDL queue virtually occupation. By analyzing the TCP traffic and ACK packets feature, the ACK packet void filling first scheduling is presented to decrease packet loss rate and to reduce the FDL voids. When the FDL buffer void size is fit for the ACK packet, the ACK packet is scheduled to FDL immediately. An ACK and non-ACK packets difference and process flow is designed according the TCP packet frame structure. Compared with the conventional FIFO scheduling and smallest FDL void first scheduling, the algorithm reduces greatly the number of ACK occupying the FDL buffer and eliminates large numbers of ACK's bad influence on efficiency of IP data transmission under different FDL buffer depth and traffic load. The results of simulation show that the proposed scheduling makes use of ACK packets first void filling scheduling mechanism to reduce FDL excess load, increases output utilization and reduce packet loss ratio for asynchronous optical network. This approach is shown to minimize the FDL numbers with the feature of high stabilization and photonic integration and to improve real time TCP traffic performance for Internet network.

  17. Effects of void size and gas content on electrical breakdown in lightweight, mechanically compliant, void-filled dielectrics

    Science.gov (United States)

    Anderson, R. A.; Lagasse, R. R.; Russick, E. M.; Schroeder, J. L.

    2002-03-01

    Dielectric potting materials (encapsulants) are used to prevent air breakdown in high-voltage electrical devices. We report breakdown strengths in void-filled encapsulants, stressed with unipolar voltage pulses of the order of 10 μs duration. High strengths, on the order of 100 kV mm-1, are measured under these test conditions. The materials studied include low-density open celled gel-derived foams with cell sizes of 4 μm or less, closed celled CO2-blown polystyrene and urethane foams, and epoxies containing 48 vol % of hollow glass microballoon (GMB) fillers. These last specimens varied the void gas (N2 or SO2) and also the void diameters (tens to hundreds of μm). Our measurements are thought to be directly sensitive to the rate of field-induced ionization events in the void gas; however, the breakdown strengths of the materials tested appeared to vary in direct proportion with the conventional Paschen-law gas-discharge inception threshold, the electric stress at which gas-ionization avalanches become possible. The GMB-epoxy specimens displayed this type of dependence of breakdown strength on the void-gas density and void size, but the measurements were an order of magnitude above the conventional predictions. Small-celled foams also showed increased breakdown strengths with decreased cell size, although their irregular void geometry prevented a direct comparison with the more uniformly structured microballoon-filled encapsulants. The experimental observations are consistent with a breakdown mechanism in which the discharge of a few voids can launch a full breakdown in the composite material.

  18. Isolation and control of voids and void-hillocks during molecular beam epitaxial growth of HgCdTe

    Science.gov (United States)

    Chandra, D.; Aqariden, F.; Frazier, J.; Gutzler, S.; Orent, T.; Shih, H. D.

    2000-06-01

    Formation of small voids and defect complexes involving small voids during the molecular beam epitaxial growth of mercury cadmium telluride on cadmium zinc telluride was investigated. Some of these defects were demonstrated to form away from the substrate-epi interface. Other defects were demonstrated to close before reaching the top surface without leaving any perturbations on the surface, thus remaining completely hidden. The voids, which formed away from the substrate-epifilm fixed interface, nucleated on defects introduced into the film already grown, leading to the formation of defect complexes, unlike the voids which nucleated at the substrate-epifilm fixed interface. These defect complexes are decorated with high density dislocation nests. The voids which closed before reaching the film surface usually also nucleated slightly away from the film-substrate interface, continued to replicate for a while as the growth progressed, but then relatively rapidly closed off at a significant depth from the film surface. These voids also appeared to form defect complexes with other kinds of defects. Correlations between these materials defects and performance of individual vertically integrated photodiode (VIP) devices were demonstrated, where the relative location of these defects with respect to the junction boundary appears to be particularly important. Elimination or reduction of fluctuations in relative flux magnitudes or substrate temperature, more likely during multi-composition layer growth, yielded films with significantly lower defect concentrations.

  19. Breaking the vicious circle: Onabotulinum toxin A in children with therapy-refractory dysfunctional voiding

    NARCIS (Netherlands)

    L.A. 't Hoen (Lisette); J. van den Hoek (Joop); K.P. Wolffenbuttel (Katja); F. van der Toorn; J.R. Scheepe (Jeroen)

    2015-01-01

    textabstractIntroduction An increased activity of the external urethral sphincter or pelvic floor muscles during voluntary voiding leads to dysfunctional voiding. Frequently reported symptoms are urinary incontinence, urinary tract infections and high post-void residuals. Dysfunctional voiding is a

  20. Size-effects at a crack-tip interacting with a number of voids

    DEFF Research Database (Denmark)

    Tvergaard, Viggo; Niordson, Christian Frithiof

    2008-01-01

    of the characteristic material length relative to the initial void radius. For a case showing the multiple void mechanism, it is found that the effect of the material length can change the behaviour towards the void by void mechanism. A material model with three characteristic length scales is compared with a one...

  1. A study of process induced voids in resistance welding of thermoplastic composites

    NARCIS (Netherlands)

    Shi, H.; Fernandez Villegas, I.; Bersee, H.E.N.

    2015-01-01

    Void formation in resistance welding of woven fabric reinforced thermoplastic composites was investigated. Void contents were measured using optical microscopy and digital image process. Un-even void distributions were observed in the joints, and more voids were found in the middle of the joints tha

  2. Irradiation creep relaxation of void swelling-driven stresses

    Energy Technology Data Exchange (ETDEWEB)

    Hall, M.M., E-mail: hallmm63@comcast.net [MacRay Consulting, 1366 Hillsdale Drive, Monroeville, PA (United States)

    2013-01-15

    Highlights: Black-Right-Pointing-Pointer Irradiation void swelling can cause distortion of reactor core components. Black-Right-Pointing-Pointer Constrained swelling can drive stresses beyond acceptable levels. Black-Right-Pointing-Pointer Compressive stresses decrease irradiation swelling rates. Black-Right-Pointing-Pointer Irradiation creep relaxes swelling-driven stresses and core restraint forces. Black-Right-Pointing-Pointer Swelling-driven creep stresses are consistent with predictions of a proposed model. - Abstract: Swelling-driven-creep test specimens are used to measure the compressive stresses that develop due to constraint of irradiation void swelling. These specimens use a previously non-irradiated 20% CW Type 316 stainless steel holder to axially restrain two Type 304 stainless steel tubular specimens that were previously irradiated in the US Experimental Breeder Reactor (EBR-II) at 490 Degree-Sign C. One specimen was previously irradiated to fluence levels in the void nucleation regime (9 dpa) and the other in the quasi-steady void growth regime (28 dpa). A lift-off compliance measurement technique was used post-irradiation to determine compressive stresses developed during reirradiation of the two specimen assemblies in Row 7 of EBR-II at temperatures of 547 Degree-Sign C and 504 Degree-Sign C, respectively, to additional damage levels each of about 5 dpa. Results obtained on the higher fluence swelling-driven-creep specimen show that compressive stress due to constraint of swelling retards void swelling to a degree that is consistent with active load uniaxial compression specimens that were irradiated as part of a previously reported multiaxial in-reactor creep experiment. Swelling results obtained on the lower fluence swelling-driven creep specimen show a much larger effect of compressive stress in reducing swelling, demonstrating that the larger effect of stress on swelling is on void nucleation as compared to void growth. Test results are

  3. New models to support the professional education of health visitors: A qualitative study of the role of space and place in creating 'community of learning hubs'.

    Science.gov (United States)

    Donetto, Sara; Malone, Mary; Sayer, Lynn; Robert, Glenn

    2017-07-01

    In response to a policy-driven workforce expansion in England new models of preparing health visitors for practice have been implemented. 'Community of Learning hubs' (COLHs) are one such model, involving different possible approaches to student support in clinical practice placements (for example, 'long arm mentoring' or 'action learning set' sessions). Such models present opportunities for studying the possible effects of spatiality on the learning experiences of students and newly qualified health visitors, and on team relationships more broadly. To explore a 'community of learning hub' model in health visitor education and reflect on the role of space and place in the learning experience and professional identity development of student health visitors. Qualitative research conducted during first year of implementation. Three 'community of learning hub' projects based in two NHS community Trusts in London during the period 2013-2015. Managers and leads (n=7), practice teachers and mentors (n=6) and newly qualified and student health visitors (n=16). Semi-structured, audio-recorded interviews analysed thematically. Participants had differing views as to what constituted a 'hub' in their projects. Two themes emerged around the spaces that shape the learning experience of student and newly qualified health visitors. Firstly, a generalised need for a 'quiet place' which allows pause for reflection but also for sharing experiences and relieving common anxieties. Secondly, the role of physical arrangements in open-plan spaces to promote access to support from more experienced practitioners. Attention to spatiality can shed light on important aspects of teaching and learning practices, and on the professional identities these practices shape and support. New configurations of time and space as part of educational initiatives can surface new insights into existing practices and learning models. Copyright © 2017. Published by Elsevier Ltd.

  4. Cause Analysis on the Void under Slabs of Cement Concrete Pavement

    Science.gov (United States)

    Wen, Li; Zhu, Guo Xin; Baozhu

    2017-06-01

    This paper made a systematic analysis on the influence of the construction, environment, water and loads on the void beneath road slabs, and also introduced the formation process of structural void and pumping void, and summarizes the deep reasons for the bottom of the cement concrete pavement. Based on the analysis above, this paper has found out the evolution law of the void under slabs which claimed that the void usually appeared in the slab corners and then the cross joint, resulting void in the four sides with the void area under the front slab larger than the rear one.

  5. THE INSTABILITY OF THE DIFFUSION-CONTROLLED GRAIN-BOUNDARY VOID IN STRESSED SOLID

    Institute of Scientific and Technical Information of China (English)

    王华; 李中华

    2003-01-01

    As atoms migrate along a void surface and grain-boundary, driven by various thermodynamic forces, the grain-boundary void changes its shape and volume. When the void changes its configuration, the free energy of the system also changes. In this article, the free energy is calculated for an evolving grain-boundary void filled with gas in a stressed solid. Then the instability conditions and the equilibrium shape of the void are determined as a function of the grain-boundary and surface energies, the void volume, the externally applied stresses, as well as the internal pressure built up by the gas filled in the void.

  6. Autonomous robot for detecting subsurface voids and tunnels using microgravity

    Science.gov (United States)

    Wilson, Stacy S.; Crawford, Nicholas C.; Croft, Leigh Ann; Howard, Michael; Miller, Stephen; Rippy, Thomas

    2006-05-01

    Tunnels have been used to evade security of defensive positions both during times of war and peace for hundreds of years. Tunnels are presently being built under the Mexican Border by drug smugglers and possibly terrorists. Several have been discovered at the border crossing at Nogales near Tucson, Arizona, along with others at other border towns. During this war on terror, tunnels under the Mexican Border pose a significant threat for the security of the United States. It is also possible that terrorists will attempt to tunnel under strategic buildings and possibly discharge explosives. The Center for Cave and Karst Study (CCKS) at Western Kentucky University has a long and successful history of determining the location of caves and subsurface voids using microgravity technology. Currently, the CCKS is developing a remotely controlled robot which will be used to locate voids underground. The robot will be a remotely controlled vehicle that will use microgravity and GPS to accurately detect and measure voids below the surface. It is hoped that this robot will also be used in military applications to locate other types of voids underground such as tunnels and bunkers. It is anticipated that the robot will be able to function up to a mile from the operator. This paper will describe the construction of the robot and the use of microgravity technology to locate subsurface voids with the robot.

  7. The Aspen--Amsterdam Void Finder Comparison Project

    CERN Document Server

    Colberg, Joerg M; Foster, Caroline; Platen, Erwin; Brunino, Riccardo; Neyrinck, Mark; Basilakos, Spyros; Fairall, Anthony; Feldman, Hume; Gottloeber, Stefan; Hahn, Oliver; Hoyle, Fiona; Mueller, Volker; Nelson, Lorne; Plionis, Manolis; Porciaini, Cristiano; Shandarin, Sergei; Vogeley, Michael S; van de Weygaert, Rien

    2008-01-01

    Despite a history that dates back at least a quarter of a century studies of voids in the large--scale structure of the Universe are bedevilled by a major problem: there exist a large number of quite different void--finding algorithms, a fact that has so far got in the way of groups comparing their results without worrying about whether such a comparison in fact makes sense. Because of the recent increased interest in voids, both in very large galaxy surveys and in detailed simulations of cosmic structure formation, this situation is very unfortunate. We here present the first systematic comparison study of thirteen different void finders constructed using particles, haloes, and semi--analytical model galaxies extracted from a subvolume of the Millennium simulation. The study includes many groups that have studied voids over the past decade. We show their results and discuss their differences and agreements. As it turns out, the basic results of the various methods agree very well with each other in that they...

  8. An analytical model for porous single crystals with ellipsoidal voids

    Science.gov (United States)

    Mbiakop, A.; Constantinescu, A.; Danas, K.

    2015-11-01

    A rate-(in)dependent constitutive model for porous single crystals with arbitrary crystal anisotropy (e.g., FCC, BCC, HCP, etc.) containing general ellipsoidal voids is developed. The proposed model, denoted as modified variational model (MVAR), is based on the nonlinear variational homogenization method, which makes use of a linear comparison porous material to estimate the response of the nonlinear porous single crystal. Periodic multi-void finite element simulations are used in order to validate the MVAR for a large number of parameters including cubic (FCC, BCC) and hexagonal (HCP) crystal anisotropy, various creep exponents (i.e., nonlinearity), several stress triaxiality ratios, general void shapes and orientations and various porosity levels. The MVAR model, which involves a priori no calibration parameters, is found to be in good agreement with the finite element results for all cases considered in the rate-dependent context. The model is then used in a predictive manner to investigate the complex response of porous single crystals in several cases with strong coupling between the anisotropy of the crystal and the (morphological) anisotropy induced by the shape and orientation of the voids. Finally, a simple way of calibrating the MVAR with just two adjustable parameters is depicted in the rate-independent context so that an excellent agreement with the FE simulation results is obtained. In this last case, this proposed model can be thought as a generalization of the Gurson model in the context of porous single crystals and general ellipsoidal void shapes and orientations.

  9. Only the Lonely: H I Imaging of Void Galaxies

    CERN Document Server

    Kreckel, K; Aragón-Calvo, M A; van Gorkom, J H; van de Weygaert, R; van der Hulst, J M; Kovač, K; Yip, C -W; Peebles, P J E

    2010-01-01

    Void galaxies, residing within the deepest underdensities of the Cosmic Web, present an ideal population for the study of galaxy formation and evolution in an environment undisturbed by the complex processes modifying galaxies in clusters and groups, as well as provide an observational test for theories of cosmological structure formation. We have completed a pilot survey for the HI imaging aspects of a new Void Galaxy Survey (VGS), imaging 15 void galaxies in HI in local (d < 100 Mpc) voids. HI masses range from 3.5 x 10^8 to 3.8 x 10^9 M_sun, with one nondetection with an upper limit of 2.1 x 10^8 M_sun. Our galaxies were selected using a structural and geometric technique to produce a sample that is purely environmentally selected and uniformly represents the void galaxy population. In addition, we use a powerful new backend of the Westerbork Synthesis Radio Telescope that allows us to probe a large volume around each targeted galaxy, simultaneously providing an environmentally constrained sample of for...

  10. Constraints on Cosmology and Gravity from the Dynamics of Voids

    Science.gov (United States)

    Hamaus, Nico; Pisani, Alice; Sutter, P. M.; Lavaux, Guilhem; Escoffier, Stéphanie; Wandelt, Benjamin D.; Weller, Jochen

    2016-08-01

    The Universe is mostly composed of large and relatively empty domains known as cosmic voids, whereas its matter content is predominantly distributed along their boundaries. The remaining material inside them, either dark or luminous matter, is attracted to these boundaries and causes voids to expand faster and to grow emptier over time. Using the distribution of galaxies centered on voids identified in the Sloan Digital Sky Survey and adopting minimal assumptions on the statistical motion of these galaxies, we constrain the average matter content Ωm=0.281 ±0.031 in the Universe today, as well as the linear growth rate of structure f /b =0.417 ±0.089 at median redshift z ¯=0.57 , where b is the galaxy bias (68% C.L.). These values originate from a percent-level measurement of the anisotropic distortion in the void-galaxy cross-correlation function, ɛ =1.003 ±0.012 , and are robust to consistency tests with bootstraps of the data and simulated mock catalogs within an additional systematic uncertainty of half that size. They surpass (and are complementary to) existing constraints by unlocking cosmological information on smaller scales through an accurate model of nonlinear clustering and dynamics in void environments. As such, our analysis furnishes a powerful probe of deviations from Einstein's general relativity in the low-density regime which has largely remained untested so far. We find no evidence for such deviations in the data at hand.

  11. Evaluation of the Air Void Analyzer

    Science.gov (United States)

    2013-07-01

    sample of concrete. The pore space components are broken down as follows (Carlson 2005; Mindess et al. 2003; Mehta and Monteiro 2006; Taylor et al. 2007...air bubbles act as small, compressible ball bearings that reduce friction between aggregates in the mixture ( Mindess et al. 2003). Air also prevents...Monteiro. 2006. Concrete: Microstructure, properties and materials. 3rd ed. New York: McGraw-Hill. ERDC/GSL TR-13-31 84 Mindess , S., J. F

  12. [Development of remote wireless mobile voiding diary and a report of its objective voiding in 20 young people].

    Science.gov (United States)

    Guan, Zhi-chen; Wei, Ben-lin; Meng, Zuo-wei

    2010-08-18

    To find out the data of the micturitions in healthy young people with the remote & mobile voiding diary monitoring system. Twenty healthy young people were studied and ten of them were female. The ages ranged from 22 to 35 years (the mean age: 27.4 years). The females were 22-33 years old (the mean age: 26.4 years ) and the males 24-35 years old (the mean age: 28.4 years). With the remote & mobile voiding diary monitoring system, their voiding information was collected. Through bluetooth, the voiding information was sent to the patient's intelligent cell phone from the collector, then stored directly by intelligent cell phone and wirelessly transmitted to the workstation in the hospital. All of them completed the voiding diaries for 7 days and the data were analyzed. The average micturition of the young healthy people was 5.6 times (3.4-7.4) per 24 hours,in which 5.3 (3.4-7.3) times were in the daytime and 0.3 (0-1.3)times in the night. The functional voiding volume was 318 mL (66-642 mL). The mean voiding volume in 24 hours was 1 724 mL (1152-2 415 mL), in which 1 289 mL (786-2 039 mL) was in the daytime and 435 mL (292-805 mL) in the night. The mean drinking volume was 1 022 mL (453-1 721 mL) in the daytime and 7 mL (0-43 mL) in the night. The nocturia index (Ni) was 1.03, the nocturnal polyuria index (NPi) 26%, and the nocturnal bladder capacity index (NBCi) 0.27. The remote & mobile voiding diary monitoring system can help us get the objective voiding information from young health people for the first time. It is reliable, maneuverable and can be widely used in clinical diagnosis.

  13. Cosmological Black Holes as Seeds of Voids in Galaxy Distribution

    CERN Document Server

    Capozziello, S; Stornaiolo, C; Capozziello, Salvatore; Funaro, Maria; Stornaiolo, Cosimo

    2004-01-01

    Deep surveys indicate a bubbly structure of cosmological large scale which should be the result of evolution of primordial density perturbations. Several models have been proposed to explain origin and dynamics of such features but, till now, no exhaustive and fully consistent theory has been found. We discuss a model where cosmological black holes, deriving from primordial perturbations, are the seeds for large-scale-structure voids. We give details of dynamics and accretion of the system voids-cosmological black holes from the epochs $(z\\simeq10^{3})$ till now finding that void of $40h^{-1}Mpc$ of diameter and under-density of -0.9 will fits the observations without conflicting with the homogeneity and isotropy of cosmic microwave background radiation.

  14. Avoid a Void: The Eradication of Null Dereferencing

    Science.gov (United States)

    Meyer, Bertrand; Kogtenkov, Alexander; Stapf, Emmanuel

    All object-oriented programs, but also those in C or Pascal as soon as they use pointers, are subject to the risk of run-time crash due to "null pointer dereferencing". Until recently this was the case even in statically typed languages. Tony Hoare has called this problem his "billion-dollar mistake". In the type system of ISO-standard Eiffel, the risk no longer exists: void safety (the absence of null pointer dereferencing) has become a property guaranteed by the type system and enforced by the compiler. The mechanism is fully implemented and major libraries and applications have been made void-safe. This presentation describes the principles of Eiffel's void safety, their implementation and the lessons gained.

  15. Dwarf Galaxies in Voids: Dark Matter Halos and Gas Cooling

    CERN Document Server

    Hoeft, Matthias

    2010-01-01

    Galaxy surveys have shown that luminous galaxies are mainly distributed in large filaments and galaxy clusters. The remaining large volumes are virtually devoid of luminous galaxies. This is in concordance with the formation of the large-scale structure in Universe as derived from cosmological simulations. However, the numerical results indicate that cosmological voids are abundantly populated with dark matter haloes which may in principle host dwarf galaxies. Observational efforts have in contrast revealed, that voids are apparently devoid of dwarf galaxies. We investigate the formation of dwarf galaxies in voids by hydrodynamical cosmological simulations. Due to the cosmic ultra-violet background radiation low-mass haloes show generally are reduced baryon fraction. We determine the characteristic mass below which dwarf galaxies are baryon deficient. We show that the circular velocity below which the accretion of baryons is suppressed is approximately 40 km/s. The suppressed baryon accretion is caused by the...

  16. On the void explanations of the Cold Spot

    CERN Document Server

    Marcos-Caballero, A; Martínez-González, E; Vielva, P

    2015-01-01

    The integrated Sachs-Wolfe (ISW) contribution induced on the cosmic microwave background by the presence of a supervoid as the one detected by Szapudi et al. (2015) is reviewed in this letter in order to check whether it could explain the Cold Spot (CS) anomaly. Two different models, previously used for the same purpose, are considered to describe the matter density profile of the void: a top hat function and a compensated profile produced by a Gaussian potential. The analysis shows that, even enabling ellipticity changes or different values for the dark-energy equation of state parameter $\\omega$, the ISW contribution due to the presence of the void does not reproduce the properties of the CS. Finally, the probability of alignment between the void and the CS is also questioned as an argument in favor of a physical connection between these two phenomena.

  17. Study of void sizes and loading configurations effects on shock initiation due to void collapse in heterogeneous energetic materials

    Science.gov (United States)

    Roy, Sidhartha; Rai, Nirmal; Udaykumar, H. S.

    2015-06-01

    In heterogeneous energetic materials, presence of porosity has been seen to increase its sensitivity towards shock initiation and ignition. Under the application of shock load, the viscoplastic deformation of voids and its collapse leads to the formation of local high temperature regions known as hot spots. The chemical reaction triggers at the hot spot depending on the local temperature and grows eventually leading to ignition and formation of detonation waves in the material. The temperature of the hot spot depends on various factors such as shock strength, void size, void arrangements, loading configuration etc. Hence, to gain deeper understanding on shock initiation and ignition study due to void collapse, a parametric study involving various factors which can affect the hot spot temperature is desired. In the current work, effects of void sizes, shock strength and loading configurations has been studied for shock initiation in HMX using massively parallel Eulerian code, SCIMITAR3D. The chemical reaction and decomposition for HMX has been modeled using Henson-Smilowitz multi step mechanism. The effect of heat conduction has also been taken into consideration. Ignition threshold criterion has been established for various factors as mentioned. The critical hot spot temperature and its size which can lead to ignition has been obtained from numerical experiments.

  18. Void-Free Lid for Food Packaging

    Science.gov (United States)

    Watson, C. D.; Farris, W. P.

    1986-01-01

    Flexible cover eliminates air pockets in sealed container. Universal food-package lid formed from flexible plastic. Partially folded, lid unfolded by depressing center portion. Height of flat portion of lid above flange thereby reduced. Pressure of food against central oval depression pops it out, forming dome that provides finger grip for mixing contents with water or opening lid. Therefore food stays fresh, allows compact stacking of partially filled containers, and resists crushing. Originally developed for packaging dehydrated food for use in human consumption on Space Shuttle missions. Other uses include home canning and commercial food packaging.

  19. Voiding trial outcome following pelvic floor repair without incontinence procedures

    Science.gov (United States)

    Wang, Rui; Won, Sara; Haviland, Miriam J.; Bargen, Emily Von; Hacker, Michele R.; Li, Janet

    2016-01-01

    Introduction and hypothesis Our aim was to identify predictors of postoperative voiding trial failure among patients who had a pelvic floor repair without a concurrent incontinence procedure in order to identify low-risk patients in whom postoperative voiding trials may be modified. Methods We conducted a retrospective cohort study of women who underwent pelvic floor repair without concurrent incontinence procedures at two institutions from 1 November 2011 through 13 October 2013 after abstracting demographic and clinical data from medical records. The primary outcome was postoperative retrograde voiding trial failure. We used modified Poisson regression to calculate the risk ratio (RR) and 95 % confidence interval (CI). Results Of the 371 women who met eligibility criteria, 294 (79.2 %) had complete data on the variables of interest. Forty nine (16.7%) failed the trial, and those women were less likely to be white (p = 0.04), more likely to have had an anterior colporrhaphy (p = 0.001), and more likely to have had a preoperative postvoid residual (PVR) ≥150 ml (p = 0.001). After adjusting for race, women were more likely to fail their voiding trial if they had a preoperative PVR of ≥150 ml (RR: 1.9; 95 % CI: 1.1–3.2); institution also was associated with voiding trial failure (RR: 3.0; 95 % CI: 1.6–5.4). Conclusions Among our cohort, postoperative voiding trial failure was associated with a PVR of ≥150 ml and institution at which the surgery was performed. PMID:26886553

  20. Experimental and numerical investigation of voids distribution in VPI for ITER correction coil

    Energy Technology Data Exchange (ETDEWEB)

    Li, Juping, E-mail: ljping@ipp.ac.cn; Wu, Jiefeng; Yu, Xiaowu

    2015-06-15

    Highlights: • A sample of correction coil was treated by vacuum pressure impregnation. • The voids in sample were observed by computed tomography. • The voids distributions were simulated in 2-D and 3-D model. • The calculated voids locations had a good agreement with experiment. • The simulation was not accurate in calculating the voids content. - Abstract: The experimental and numerical investigations were conducted to study the voids distribution in VPI (Vacuum Pressure Impregnation) process for correction coil. A sample of correction coil was manufactured by VPI. The voids in sample were observed with computed tomography and the average voids content was tested. The voids content is closely related to infiltration velocity and fluid properties. In former researches, the parameters affecting voids content were combined into a single parameter, namely capillary number. By calculating the capillary numbers in different areas of the sample, the voids distribution could be acquired. The corresponding numerical analyses based on Darcy law were conducted in 2-D and 3-D models. The 2-D case was used to simulate the voids distribution on the section as a simplified model, while the 3-D case demonstrated the spatial distribution of voids. The voids locations were similar in 2-D and 3-D cases, but the voids contents were different. The numerical results were compared with the actual voids distribution in sample. It was found the voids locations were close in numerical and experimental results, but the voids content did not match. The numerical simulations are available for predicting the voids locations in VPI, but not accurate in calculating the voids content.

  1. Spaces

    Directory of Open Access Journals (Sweden)

    Maziar Nekovee

    2010-01-01

    Full Text Available Cognitive radio is being intensively researched as the enabling technology for license-exempt access to the so-called TV White Spaces (TVWS, large portions of spectrum in the UHF/VHF bands which become available on a geographical basis after digital switchover. Both in the US, and more recently, in the UK the regulators have given conditional endorsement to this new mode of access. This paper reviews the state-of-the-art in technology, regulation, and standardisation of cognitive access to TVWS. It examines the spectrum opportunity and commercial use cases associated with this form of secondary access.

  2. Voiding patterns in men evaluated by a questionnaire survey

    DEFF Research Database (Denmark)

    Sommer, P; Nielsen, K K; Bauer, T;

    1990-01-01

    A questionnaire on obstructive and irritative voiding symptoms was sent to 572 men aged between 20 and 79 years, selected at random from the National Register; 337 questionnaires were completed. None of the responders had consulted a doctor because of voiding symptoms. There was a significant...... had symptoms equal in severity to those found in men undergoing prostatectomy; 29% and 11% of men in the eighth decade [corrected] had nocturia twice and 3 times or more respectively; 19% complained of urge incontinence. More information on possible treatment is needed....

  3. Effects of Heterogeneous Sink Distribution on Void Swelling

    DEFF Research Database (Denmark)

    Leffers, Torben; Volobuyev, A. V.; Gann, V. V.

    1986-01-01

    Swelling rates are calculated for two types of material with heterogeneous distributions of dislocations and voids, namely copper irradiated with neutrons to low dose at 250 degree C and heavily cold-worked copper irradiated with 1 MeV electrons in a HVEM at 250 degree C. Both materials...... are considered to consist of non-interacting spherical components with a wall and an inner cell with different dislocation and/or void densities. We subdivide the sphere (wall plus cell) in a number of concentric shells and find a quasi-static solution for the interstitial and vacancy concentrations...

  4. The Quality Control Algorithms Used in the Process of Creating the NASA Kennedy Space Center Lightning Protection System Towers Meteorological Database

    Science.gov (United States)

    Orcutt, John M.; Brenton, James C.

    2016-01-01

    The methodology and the results of the quality control (QC) process of the meteorological data from the Lightning Protection System (LPS) towers located at Kennedy Space Center (KSC) launch complex 39B (LC-39B) are documented in this paper. Meteorological data are used to design a launch vehicle, determine operational constraints, and to apply defined constraints on day-of-launch (DOL). In order to properly accomplish these tasks, a representative climatological database of meteorological records is needed because the database needs to represent the climate the vehicle will encounter. Numerous meteorological measurement towers exist at KSC; however, the engineering tasks need measurements at specific heights, some of which can only be provided by a few towers. Other than the LPS towers, Tower 313 is the only tower that provides observations up to 150 m. This tower is located approximately 3.5 km from LC-39B. In addition, data need to be QC'ed to remove erroneous reports that could pollute the results of an engineering analysis, mislead the development of operational constraints, or provide a false image of the atmosphere at the tower's location.

  5. TRANSVERSELY ISOTROPIC HYPER-ELASTIC MATERIAL RECTANGULAR PLATE WITH VOIDS UNDER A UNIAXIAL EXTENSION

    Institute of Scientific and Technical Information of China (English)

    程昌钧; 任九生

    2003-01-01

    The finite deformation and stress analyses for a transversely isotropic rectangularplate with voids and made of hyper-elastic material with the generalized neo-Hookean strainenergy function under a uniaxial extension are studied. The deformation functions of plateswith voids that are symmetrically distributed in a certain manner are given and the functionsare expressed by two parameters by solving the differential equations. The solution may beapproximately obtained from the minimum potential energy principle. Thus, the analyticsolutions of the deformation and stress of the plate are obtained. The growth of the void.s andthe distribution of stresses along the voids are analyzed and the influences of the degree ofanisotropy, the size of the voids and the distance between the voids are discussed. Thecharacteristics of the growth of the voids and the distribution of stresses of the plates with onevoid, three or five voids are obtained and compared.

  6. Shapes and Sizes of Voids in the LCDM Universe: Excursion Set Approach

    CERN Document Server

    Shandarin, S; Heitmann, K; Habib, S; Shandarin, Sergei; Feldman, Hume A.; Heitmann, Katrin

    2006-01-01

    We study the global distribution and morphology of dark matter voids in a LCDM universe using density fields generated by N-body simulations. Voids are defined as isolated regions of the low-density excursion set specified via density thresholds, the density thresholds being quantified by the corresponding filling factors, i.e., the fraction of the total volume in the excursion set. Our work encompasses a systematic investigation of the void volume function, the volume fraction in voids, and the fitting of voids to corresponding ellipsoids and spheres. We emphasize the relevance of the percolation threshold to the void volume statistics of the density field both in the high redshift, Gaussian random field regime, as well as in the present epoch. By using measures such as the Inverse Porosity, we characterize the quality of ellipsoidal fits to voids, finding that such fits are a poor representation of the larger voids that dominate the volume of the void excursion set.

  7. SURFACE EFFECT ON NANOSIZED VOID GROWTH IN A RIGID-PERFECTLY PLASTIC MATERIAL

    Institute of Scientific and Technical Information of China (English)

    Tong Hui; Yiheng Chen

    2008-01-01

    The influence of the surface effect on the nanosized spherical void growth in a rigid-perfectly plastic material is analyzed and the mechanism of the nanosized void growth with high triaxiality is given. Based on the Rice and Tracey model for a macro void growth, the present model is proposed to account for the nanosized void growth under a uniform remote strain rate field with consideration on the surface effect. It is concluded that the surface effect yields an evident resistant influence on the nanosized void growth. That is, this influence decays as the void radius increases. With high triaxiality, the nanosized void growth is divided into two stages:the initial stage and the mature stage. At the first stage, the void grows slowly and the influence of surface effect is relatively weak, whereas at the second stage, the influene is significant and the void grows drastically.

  8. How to use the cosmological Schwinger principle for energy flux, entropy, and 'atoms of space-time' to create a thermodynamic space-time and multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Beckwith, Andrew, E-mail: beckwith@iibep.org [71 Lakewood court, apt 7, Moriches, New York, 11955 (United States)

    2011-07-08

    We make explicit an idea by Padmanabhan in DICE 2010, as to finding 'atoms of space-time' permitting a thermodynamic treatment of emergent structure similar to Gibbs treatment of statistical physics. That is, an ensemble of gravitons is used to give an 'atom' of space-time congruent with relic GW. The idea is to reduce the number of independent variables to get a simple emergent space-time structure of entropy. An electric field, based upon the cosmological Schwinger principle, is linked to relic heat flux, with entropy production tied in with candidates as to inflaton potentials. The effective electric field links with the Schwinger 1951s result of an E field leading to pairs of e{sup +}e{sup -} charges nucleated in space-time volume V {center_dot} t. Note that in most inflationary models, the assumption is for a magnetic field, not an electric field. An electric field permits a kink-anti-kink construction of an emergent structure, which includes Glinka's recent pioneering approach to a Multiverse. Also an E field allows for an emergent relic particle frequency range between one and 100 GHz. The novel contribution is a relic E field, instead of a B field, in relic space-time 'atom' formation and vacuum nucleation of the same.

  9. Density Enhancements and Voids following Patchy Reconnection

    CERN Document Server

    Guidoni, S E

    2011-01-01

    We show, through a simple patchy reconnection model, that retracting reconnected flux tubes may present elongated regions relatively devoid of plasma, as well as long lasting, dense central hot regions. Reconnection is assumed to happen in a small patch across a Syrovatski\\'i (non-uniform) current sheet (CS) with skewed magnetic fields. The background magnetic pressure has its maximum at the center of the CS plane, and decreases toward the edges of the plane. The reconnection patch creates two V-shaped reconnected tubes that shorten as they retract in opposite directions, due to magnetic tension. One of them moves upward toward the top edge of the CS, and the other one moves downward toward the top of the underlying arcade. Rotational discontinuities (RDs) propagate along the legs of the tubes and generate parallel super-sonic flows that collide at the center of the tube. There, gas dynamics shocks that compress and heat the plasma are launched outwardly. The descending tube moves through the bottom part of t...

  10. Image analysis of aggregate,mastic and air void phases for asphalt mixture%Image analysis of aggregate, mastic and air void phases for asphalt mixture

    Institute of Scientific and Technical Information of China (English)

    ADHIKARI Sanjeev; YOU Zhan-ping; HAO Pei-wen; WANG Hai-nian

    2013-01-01

    The shape characterization and spatial distribution of aggregate,mastic and air void phases for asphalt mixture were analyzed.Three air void percentage asphalt mixtures,4%,7% and 8%,respectively,were cut into cross sections and polished.X-ray scanning microscope was used to capture aggregate,mastic,air void phase by the image.The average of polygon diameter was chosen as a threshold to determine which aggregates would be retained on a given sieve.The aggregate morphological image from scanned image was utilized by digital image processing method to calculate the gradation of aggregate and simulate the real gradation.Analysis result shows that the air void of asphalt mixture has influence on the correlation between calculation gradation and actual gradation.When comparing 4.75 mm sieve size of 4%,7% and 8% air void asphalt mixtures,7% air void asphalt mixture has 55% higher than actual size gradation,8% air void asphalt mixture has 8% higher than actual size gradation,and 4% air void asphalt mixture has 3.71% lower than actual size gradation.4% air void asphalt mixture has the best correlation between calculation gradation and actual gradation comparing to other specimens.The air void percentage of asphalt mixture has no obvious influence on the air void orientation,and three asphalt mixtures show the similar air orientation along the same direction.4 tabs,7 figs,17 refs.

  11. Void growth to coalescence in a non-local material

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    The size-effect in metals containing distributed spherical voids is analyzed numerically using a finite strain generalization of a length scale dependent plasticity theory. Results are obtained for stress-triaxialities relevant in front of a crack tip in an elastic-plastic metal. The influence...

  12. Void growth to coalescence in a non-local material

    DEFF Research Database (Denmark)

    Niordson, Christian Frithiof

    2008-01-01

    The size-effect in metals containing distributed spherical voids is analyzed numerically using a finite strain generalization of a length scale dependent plasticity theory. Results are obtained for stress-triaxialities relevant in front of a crack tip in an elastic-plastic metal. The influence...

  13. Kinetic Monte Carlo simulations of void lattice formation during irradiation

    Science.gov (United States)

    Heinisch, H. L.; Singh, B. N.

    2003-11-01

    Over the last decade, molecular dynamics simulations of displacement cascades have revealed that glissile clusters of self-interstitial crowdions are formed directly in cascades and that they migrate one-dimensionally along close-packed directions with extremely low activation energies. Occasionally, under various conditions, a crowdion cluster can change its Burgers vector and glide along a different close-packed direction. The recently developed production bias model (PBM) of microstructure evolution under irradiation has been structured specifically to take into account the unique properties of the vacancy and interstitial clusters produced in the cascades. Atomic-scale kinetic Monte Carlo (KMC) simulations have played a useful role in understanding the defect reaction kinetics of one-dimensionally migrating crowdion clusters as a function of the frequency of direction changes. This has made it possible to incorporate the migration properties of crowdion clusters and changes in reaction kinetics into the PBM. In the present paper we utilize similar KMC simulations to investigate the significant role that crowdion clusters can play in the formation and stability of void lattices. The creation of stable void lattices, starting from a random distribution of voids, is simulated by a KMC model in which vacancies migrate three-dimensionally and self-interstitial atom (SIA) clusters migrate one-dimensionally, interrupted by directional changes. The necessity of both one-dimensional migration and Burgers vectors changes of SIA clusters for the production of stable void lattices is demonstrated, and the effects of the frequency of Burgers vector changes are described.

  14. A cosmic watershed : the WVF void detection technique

    NARCIS (Netherlands)

    Platen, Erwin; van de Weygaert, Rien; Jones, Bernard J. T.

    2007-01-01

    On megaparsec scales the Universe is permeated by an intricate filigree of clusters, filaments, sheets and voids, the cosmic web. For the understanding of its dynamical and hierarchical history it is crucial to identify objectively its complex morphological components. One of the most characteristic

  15. Structural control of void formation in dual phase steels

    DEFF Research Database (Denmark)

    Azuma, Masafumi

    measurements, tensile tests and hole-expansion tests. The initial microstructure and the deformed microstructure were characterized by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). In situ tensile tests in a SEM were applied for direct observation of the void formation...

  16. Experimental facility and void fraction calibration methods for impedance probes

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Fernando L. de; Rocha, Marcelo S., E-mail: floliveira@ipen.br, E-mail: msrocha@ipen.br [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    An experimental facility was designed and constructed with aims of to calibrate a capacitance probe for gas-liquid flow void fraction measurements. The facility is composed of a metallic hack with a vertical 2,300 mm high glass tube with 38 mm ID with stagnant water and compressed air bubbling system simulating the gas phase (vapor). At the lower part, a mixing section with a porous media element releases the air bubbles into the water, and the compressed air flow is measured by two calibrated rotameters. At the upper part a stagnant water tank separates the liquid and gas. Two pressure taps are located near the lower and upper sides of the glass tube for pressure difference measurement. The pressure difference is used for low void fraction values (0-15%) calibration methods, as described in the work. Two electrically controlled quick closing valves are installed between the porous media element and the upward separation tank for high void fraction values measurement (15-50%) used to calibrate the capacitance probe. The experimental facility design, construction, capacitance probe calibration methods and results, as well as flow pattern visualization, are presented. Finally, the capacitance probe will be installed on a natural circulation circuit mounted at the Nuclear Engineering Center (CEN/IPEN/CNEN-SP) for measurement of the instantaneous bulk void. Instantaneous signals generated by the capacitance probe will allow the determination of natural circulation loop global energy balance. (author)

  17. Predictive efficacy of radioisotope voiding cystography for renal outcome

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Seok Ki; Lee, Dong Soo; Kim, Kwang Myeung; Choi, Whang; Chung, June Key; Lee, Myung Chul [Seoul National Univ. College of Medicine, Seoul (Korea, Republic of)

    2000-04-01

    As vesicoureteral reflux (VUR) could lead to renal functional deterioration when combined with urinary tract infection, we need to decide whether operative anti-reflux treatment should be performed at the time of diagnosis of VUR. Predictive value of radioisotope voiding cystography (RIVCG) for renal outcome was tested. In 35 children (18 males, 17 females), radiologic voiding cystoure-thrography (VCU), RIVCG and DMSA scan were performed. Change in renal function was evaluated using the follow-up DMSA scan, ultrasonography, and clinical information. Discriminant analysis was performed using individual or integrated variables such as reflux amount and extent at each phase of voiding on RIVCG, in addition to age, gender and cortical defect on DMSA scan at the time of diagnosis. Discriminant function was composed and its performance was examined. Reflux extent at the filling phase and reflux amount and extent at postvoiding phase had a significant prognostic value. Total reflux amount was a composite variable to predict prognosis. Discriminant function composed of reflux extent at the filling phase and reflux amount and extent at postvoiding phase showed better positive predictive value and specificity than conventional reflux grading. RIVCG could predict renal outcome by disclosing characteristic reflux pattern during various voiding phases.

  18. Compensation for air voids in photoacoustic computed tomography image reconstruction

    Science.gov (United States)

    Matthews, Thomas P.; Li, Lei; Wang, Lihong V.; Anastasio, Mark A.

    2016-03-01

    Most image reconstruction methods in photoacoustic computed tomography (PACT) assume that the acoustic properties of the object and the surrounding medium are homogeneous. This can lead to strong artifacts in the reconstructed images when there are significant variations in sound speed or density. Air voids represent a particular challenge due to the severity of the differences between the acoustic properties of air and water. In whole-body small animal imaging, the presence of air voids in the lungs, stomach, and gastrointestinal system can limit image quality over large regions of the object. Iterative reconstruction methods based on the photoacoustic wave equation can account for these acoustic variations, leading to improved resolution, improved contrast, and a reduction in the number of imaging artifacts. However, the strong acoustic heterogeneities can lead to instability or errors in the numerical wave solver. Here, the impact of air voids on PACT image reconstruction is investigated, and procedures for their compensation are proposed. The contributions of sound speed and density variations to the numerical stability of the wave solver are considered, and a novel approach for mitigating the impact of air voids while reducing the computational burden of image reconstruction is identified. These results are verified by application to an experimental phantom.

  19. The Effect of Random Voids in the Modified Gurson Model

    Science.gov (United States)

    Fei, Huiyang; Yazzie, Kyle; Chawla, Nikhilesh; Jiang, Hanqing

    2012-02-01

    The porous plasticity model (usually referred to as the Gurson-Tvergaard-Needleman model or modified Gurson model) has been widely used in the study of microvoid-induced ductile fracture. In this paper, we studied the effects of random voids on the porous plasticity model. Finite-element simulations were conducted to study a copper/tin/copper joint bar under uniaxial tension using the commercial finite-element package ABAQUS. A randomly distributed initial void volume fraction with different types of distribution was introduced, and the effects of this randomness on the crack path and macroscopic stress-strain behavior were studied. It was found that consideration of the random voids is able to capture more detailed and localized deformation features, such as different crack paths and different ultimate tensile strengths, and meanwhile does not change the macroscopic stress-strain behavior. It seems that the random voids are able to qualitatively explain the scattered observations in experiments while keeping the macroscopic measurements consistent.

  20. A halo bias function measured deeply into voids without stochasticity

    CERN Document Server

    Neyrinck, Mark C; Jeong, Donghui; Wang, Xin

    2013-01-01

    We study the relationship between dark-matter haloes and matter in the MIP N-body simulation ensemble, which allows precision measurements of this relationship, even deeply into voids. What enables this is a lack of discreteness, stochasticity, and exclusion, achieved by averaging over hundreds of possible sets of initial small-scale modes, while holding fixed large-scale modes that give the cosmic web. We find (i) that dark-matter-halo formation is greatly suppressed in voids; there is an exponential downturn at low densities in the otherwise power-law matter-to-halo density bias function. Thus, the rarity of haloes in voids is akin to the rarity of the largest clusters, and their abundance is quite sensitive to cosmological parameters. The exponential downturn appears both in an excursion-set model, and in a new model in which fluctuations evolve in voids as in an open universe with an effective Omega_m proportional to a large-scale density. We also find that (ii) haloes typically populate the average halo-...

  1. Electric field theory and the fallacy of void capacitance

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1991-01-01

    The concept of the capacitance of a gaseous void is discussed as applied to electrical insulation science. The most pertinent aspect of the capacitance definition is that of reference to a single-valued potential difference between surfaces. This implies that these surfaces must be surfaces...

  2. Excursion Sets and Non-Gaussian Void Statistics

    CERN Document Server

    D'Amico, Guido; Noreña, Jorge; Paranjape, Aseem

    2010-01-01

    Primordial non-Gaussianity (NG) affects the large scale structure (LSS) of the universe by leaving an imprint on the distribution of matter at late times. Much attention has been focused on using the distribution of collapsed objects (i.e. dark matter halos and the galaxies and galaxy clusters that reside in them) to probe primordial NG. An equally interesting and complementary probe however is the abundance of extended underdense regions or voids in the LSS. The calculation of the abundance of voids using the excursion set formalism in the presence of primordial NG is subject to the same technical issues as the one for halos, which were discussed e.g. in arXiv:1005.1203. However, unlike the excursion set problem for halos which involved random walks in the presence of one barrier $\\delta_c$, the void excursion set problem involves two barriers $\\delta_v$ and $\\delta_c$. This leads to a new complication introduced by what is called the "void-in-cloud" effect discussed in the literature, which is unique to the...

  3. Effect of void structure of photocatalyst paper on VOC decomposition.

    Science.gov (United States)

    Fukahori, Shuji; Iguchi, Yumi; Ichiura, Hideaki; Kitaoka, Takuya; Tanaka, Hiroo; Wariishi, Hiroyuki

    2007-02-01

    TiO2 powder-containing paper composites, called TiO2 paper, were prepared by a papermaking technique, and their photocatalytic efficiency was investigated. The TiO2 paper has a porous structure originating from the layered pulp fiber network, with TiO2 powders scattered on the fiber matrix. Under UV irradiation, the TiO2 paper decomposed gaseous acetaldehyde more effectively than powdery TiO2 and a pulp/TiO2 mixture not in paper form. Scanning electron microscopy and mercury intrusion analysis revealed that the TiO2 paper had characteristic unique voids ca. 10 microm in diameter, which might have contributed to the improved photocatalytic performance. TiO2 paper composites having different void structures were prepared by using beaten pulp fibers with different degrees of freeness and/or ceramic fibers. The photodecomposition efficiency was affected by the void structure of the photocatalyst paper, and the initial degradation rate of acetaldehyde increased with an increase in the total pore volume of TiO2 paper. The paper voids presumably provided suitable conditions for TiO2 catalysis, resulting in higher photocatalytic performance by TiO2 paper than by TiO2 powder and a pulp/TiO2 mixture not in paper form.

  4. The cosmic web in CosmoGrid void regions

    NARCIS (Netherlands)

    Rieder, Steven; van de Weygaert, Rien; Cautun, Marius; Beygu, Burcu; Portegies Zwart, Simon

    2016-01-01

    We study the formation and evolution of the cosmic web, using the high-resolution CosmoGrid ΛCDM simulation. In particular, we investigate the evolution of the large-scale structure around void halo groups, and compare this to observations of the VGS-31 galaxy group, which consists of three interact

  5. Calculation of Void in the Fort Saint Vrain Material

    Energy Technology Data Exchange (ETDEWEB)

    Potter, David Charles [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Taylor, Craig Michael [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Coons, James Elmer [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-11

    The percent void of the Fort Saint Vrain (FSV) material is estimated to be 21.1% based on the volume of the gap at the top of the drums, the volume of the coolant channels in the FSV fuel element, and the volume of the fuel handling channel in the FSV fuel element.

  6. An HI survey of the bootes void; 2, the analysis

    CERN Document Server

    Szomoru, A; Gregg, M D; Strauss, M A

    1995-01-01

    We discuss the results of a VLA HI survey of the Bootes void and compare the distribution and HI properties of the void galaxies to those of galaxies found in a survey of regions of mean cosmic density. The Bootes survey covers 1100 Mpc^{3}, or \\sim 1\\% of the volume of the void and consists of 24 cubes of typically 2 Mpc * 2 Mpc * 1280 km/s, centered on optically known galaxies. Sixteen targets were detected in HI; 18 previously uncataloged objects were discovered directly in HI. The control sample consists of 12 cubes centered on IRAS selected galaxies with FIR luminosities similar to those of the Bootes targets and located in regions of 1 to 2 times the cosmic mean density. In addition to the 12 targets 29 companions were detected in HI. We find that the number of galaxies within 1 Mpc of the targets is the same to within a factor of two for void and control samples, and thus that the small scale clustering of galaxies is the same in regions that differ by a factor of \\sim 6 in density on larger scales. A ...

  7. The Aspen–Amsterdam Void Finder Comparison Project

    NARCIS (Netherlands)

    Colberg, J¨org M.; Pearce, Frazer; Foster, Caroline; Platen, Erwin; Brunino, Riccardo; Neyrinck, Mark; Basilakos, Spyros; Faira, Anthony; Feldman, Hume; Gottlöber, Stefan; Hahn, Oliver; Hoyle, Fiona; M¨uller, V.; Nelson, Lorne; Plionis, Manolis; Porciani, Cristiano; Shandarin, Sergei; Vogeley, Michael S.; Weygaert, Rien van de

    2008-01-01

    Despite a history that dates back at least a quarter of a century studies of voids in the large–scale structure of the Universe are bedevilled by a major problem: there exist a large number of quite different void–finding algorithms, a fact that has so far got in the way of groups comparing their

  8. Low-void polyimide resins for autoclave processing

    Science.gov (United States)

    Jones, R. J.; Vaughan, R. W.

    1972-01-01

    Development of an advanced A-type polyimide, which can be used to produce autoclave molded, low-void content composites suitable for use at temperatures up to 316 C is reported. It consists of a mixture of methyl nadic anhydride, an 80:20 molar ratio of methylene dianaline and thiodianilene, and pyromellitic dianhydride.

  9. Answers from the Void: VIDE and its Applications

    Science.gov (United States)

    Sutter, P. M.; Hamaus, N.; Pisani, A.; Lavaux, G.; Wandelt, B. D.

    2016-10-01

    We discuss various applications ofvide, the Void IDentification and Examination toolkit, anopen-source Python/C++ code for finding cosmic voids in galaxy redshift surveysand $N$-body simulations.Based on a substantially enhanced version of ZOBOV, vide not only finds voids, but alsosummarizes their properties, extracts statisticalinformation, and providesa Python-based platform for more detailed analysis, such asmanipulating void catalogs and particle members, filtering, plotting,computing clustering statistics, stacking, comparing catalogs, andfitting density profiles.vide also provides significant additional functionality forpre-processing inputs: for example, vide can work with volume- ormagnitude-limited galaxy samples with arbitrary survey geometries,or darkmatter particles or halo catalogs in a variety of common formats.It can also randomly subsample inputsand includes a Halo Occupation Distribution model forconstructing mock galaxy populations.vide has been used for a wide variety of applications, fromdiscovering a universal density profile to estimatingprimordial magnetic fields, andis publicly available athttp://bitbucket.org/cosmicvoids/vide\\_publicandhttp://www.cosmicvoids.net.

  10. The Instability of Void Fraction Waves in Vertical Gas—Liquid Two—Phase Flow

    Institute of Scientific and Technical Information of China (English)

    BaojiangSUN; DachunYAN; 等

    1999-01-01

    The measuring and analyzing results of void fraction waves in different flow regimes show that the propagating velocity of void fraction waves depends on flow regimes and mean void fraction.The disturbance at some frequencies can enhance the void fraction wave velocity.Non-linear analysis show that the instability process of bubble flow is a chaotic process.Before the bubbly flow transits to cap-bubbly flow the growth rate of void fraction waves becomes the maximum value when the disturbance frequency is around the main frequency of void fraction waves.

  11. Effects of Cure Pressure Induced Voids on the Mechanical Strength of Carbon/Epoxy Laminates

    Institute of Scientific and Technical Information of China (English)

    Ling LIU; Boming ZHANG; Zhanjun WU; Dianfu WANG

    2005-01-01

    This work aims at designing a set of curing pressure routes to produce laminates with various void contents. The effects of various consolidation pressures resulting in different void contents on mechanical strength of carbon/epoxy laminates have been examined. Characterization of the voids, in terms of void volume fraction, void distribution,size, and shape, was performed by standard test, ultrasonic inspection and metallographic analysis. The interlaminar shear strength was measured by the short-beam method. An empirical model was used to predict the strength vs porosity. The predicted strengths conform well with the experimental data and voids were found to be uniformly distributed throughout the laminate.

  12. On the linearity of tracer bias around voids

    Science.gov (United States)

    Pollina, Giorgia; Hamaus, Nico; Dolag, Klaus; Weller, Jochen; Baldi, Marco; Moscardini, Lauro

    2017-07-01

    The large-scale structure of the Universe can be observed only via luminous tracers of the dark matter. However, the clustering statistics of tracers are biased and depend on various properties, such as their host-halo mass and assembly history. On very large scales, this tracer bias results in a constant offset in the clustering amplitude, known as linear bias. Towards smaller non-linear scales, this is no longer the case and tracer bias becomes a complicated function of scale and time. We focus on tracer bias centred on cosmic voids, i.e. depressions of the density field that spatially dominate the Universe. We consider three types of tracers: galaxies, galaxy clusters and active galactic nuclei, extracted from the hydrodynamical simulation Magneticum Pathfinder. In contrast to common clustering statistics that focus on auto-correlations of tracers, we find that void-tracer cross-correlations are successfully described by a linear bias relation. The tracer-density profile of voids can thus be related to their matter-density profile by a single number. We show that it coincides with the linear tracer bias extracted from the large-scale auto-correlation function and expectations from theory, if sufficiently large voids are considered. For smaller voids we observe a shift towards higher values. This has important consequences on cosmological parameter inference, as the problem of unknown tracer bias is alleviated up to a constant number. The smallest scales in existing data sets become accessible to simpler models, providing numerous modes of the density field that have been disregarded so far, but may help to further reduce statistical errors in constraining cosmology.

  13. STM-Induced Void Formation at the Al{sub 2}O{sub 3}/Ni{sub 3}Al(111) Interface

    Energy Technology Data Exchange (ETDEWEB)

    Magtoto, N.P.; Niu, C.; Anzaldura, M.; Kelber, J.A.; Jennison, D.R.

    2000-09-21

    Under UHV conditions at 300 K, the applied electric field and/or resulting current from an STM tip creates nanoscale voids at the interface between an epitaxial, 7.0 {angstrom} thick Al{sub 2}O{sub 3} film and a Ni{sub 3}Al(111) substrate. This phenomenon is independent of tip polarity. Constant current (1 nA) images obtained at +0.1 V bias and +2.0 bias voltage (sample positive) reveal that voids are within the metal at the interface and, when small, are capped by the oxide film. Void size increases with time of exposure. The rate of void growth increases with applied bias/field and tunneling current, and increases significantly for field strengths >5 MV/cm, well below the dielectric breakdown threshold of 12 {+-} 1 MV/cm. Slower rates of void growth are, however, observed at lower applied field strengths. Continued growth of voids, to {approximately}30 {angstrom} deep and {approximately}500 {angstrom} wide, leads to the eventual failure of the oxide overlayer. Density Functional Theory calculations suggest a reduction-oxidation (REDOX) mechanism: interracial metal atoms are oxidized via transport into the oxide, while oxide surface Al cations are reduced to admetal species which rapidly diffuse away. This is found to be exothermic in model calculations, regardless of the details of the oxide film structure; thus, the barriers to void formation are kinetic rather than thermodynamic. We discuss our results in terms of mechanisms for the localized pitting corrosion of aluminum, as our results suggest nanovoid formation requires just electric field and current, which are ubiquitous in environmental conditions.

  14. A constitutive model for elastoplastic solids containing primary and secondary voids

    Science.gov (United States)

    Fabrègue, D.; Pardoen, T.

    In many ductile metallic alloys, the damage process controlled by the growth and coalescence of primary voids nucleated on particles with a size varying typically between 1 and 100 μm, is affected by the growth of much smaller secondary voids nucleated on inclusions with a size varying typically between 0.1 and 3 μm. The goal of this work is first to quantify the potential effect of the growth of these secondary voids on the coalescence of primary voids using finite element (FE) unit cell calculations and second to formulate a new constitutive model incorporating this effect. The nucleation and growth of secondary voids do essentially not affect the growth of the primary voids but mainly accelerate the void coalescence process. The drop of the ductility caused by the presence of secondary voids increases if the nucleation strain decreases and/or if their volume fraction increases and/or if the primary voids are flat. A strong coupling is indeed observed between the shape of the primary voids and the growth of the second population enhancing the anisotropy of the ductility induced by void shape effects. The new micromechanics-based coalescence condition for internal necking introduces the softening induced by secondary voids growing in the ligament between two primary voids. The FE cell calculations were used to guide and assess the development of this model. The use of the coalescence condition relies on a closed-form model for estimating the evolution of the secondary voids in the vicinity of a primary cavity. This coalescence criterion is connected to an extended Gurson model for the first population including the effect of the void aspect ratio. With respect to classical models for single void population, this new constitutive model improves the predictive potential of damage constitutive models devoted to ductile metal while requiring only two new parameters, i.e. the initial porosity of second population and a void nucleation stress, without any additional

  15. Three-Dimensional Molecular Dynamics Simulations of Void Coalescence during Dynamic Fracture of Ductile Metals

    Energy Technology Data Exchange (ETDEWEB)

    Seppala, E T; Belak, J; Rudd, R E

    2004-09-02

    Void coalescence and interaction in dynamic fracture of ductile metals have been investigated using three-dimensional strain-controlled multi-million atom molecular dynamics simulations of copper. The correlated growth of two voids during the coalescence process leading to fracture is investigated, both in terms of its onset and the ensuing dynamical interactions. Void interactions are quantified through the rate of reduction of the distance between the voids, through the correlated directional growth of the voids, and through correlated shape evolution of the voids. The critical inter-void ligament distance marking the onset of coalescence is shown to be approximately one void radius based on the quantification measurements used, independent of the initial separation distance between the voids and the strain-rate of the expansion of the system. The interaction of the voids is not reflected in the volumetric asymptotic growth rate of the voids, as demonstrated here. Finally, the practice of using a single void and periodic boundary conditions to study coalescence is examined critically and shown to produce results markedly different than the coalescence of a pair of isolated voids.

  16. Voids and superstructures: correlations and induced large-scale velocity flows

    Science.gov (United States)

    Lares, Marcelo; Luparello, Heliana E.; Maldonado, Victoria; Ruiz, Andrés N.; Paz, Dante J.; Ceccarelli, Laura; Garcia Lambas, Diego

    2017-09-01

    The expanding complex pattern of filaments, walls and voids build the evolving cosmic web with material flowing from underdense on to high density regions. Here, we explore the dynamical behaviour of voids and galaxies in void shells relative to neighbouring overdense superstructures, using the Millenium simulation and the main galaxy catalogue in Sloan Digital Sky Survey data. We define a correlation measure to estimate the tendency of voids to be located at a given distance from a superstructure. We find voids-in-clouds (S-types) preferentially located closer to superstructures than voids-in-voids (R-types) although we obtain that voids within ∼40 h-1 Mpc of superstructures are infalling in a similar fashion independently of void type. Galaxies residing in void shells show infall towards the closest superstructure, along with the void global motion, with a differential velocity component depending on their relative position in the shell with respect to the direction to the superstructure. This effect is produced by void expansion and therefore is stronger for R-types. We also find that galaxies in void shells facing the superstructure flow towards the overdensities faster than galaxies elsewhere at the same relative distance to the superstructure. The results obtained for the simulation are also reproduced for the Sky Survey Data Release data with a linearized velocity field implementation.

  17. Comparison of voiding cystourethrography and urosonography with second-generation contrast agents in simultaneous prospective study

    Science.gov (United States)

    Świętoń, Dominik; Rybczyńska, Dorota; Czarniak, Piotr; Szarmach, Arkadiusz; Kaszubowski, Mariusz; Szurowska, Edyta

    2016-01-01

    Background The invasiveness and exposure to radiation in voiding cystourethrography led to the introduction of alternative methods of diagnosis of vesicoureteral reflux, including contrast enhanced voiding urosonography. While there is a limited number of studies comparing these methods using new generation ultrasound contrast agents, none of them compared both methods simultaneously. This study is aimed at assessing agreement between contrast enhanced voiding urosonography with second-generation ultrasound contrast agents and voiding cystourethrography. Methods From April 2013 to May 2014, 83 children (37 female and 46 male), mean age 3.5 years, age range from 1 month to 17.5 years, underwent prospective simultaneous assessment by contrast enhanced voiding urosonography and voiding cystourethrography, with a total of 166 uretero-renal units evaluated. Results The sensitivity of voiding cystourethrography and contrast enhanced voiding urosonography were comparable, amounting to 88%, however, neither reached 100% for the entire studied population. The negative predictive value of voiding urosonography and voiding cystourethrography was 97%, and there was no difference between both methods. Conclusion Voiding cystourethrography and contrast enhanced voiding urosonography are comparable methods in diagnosis of vesicoureteral reflux, and can be performed alternatively. However, some limitations of contrast enhanced voiding urosonography must be remembered.

  18. In Situ Void Fraction and Gas Volume in Hanford Tank 241-SY-101 as Measured with the Void Fraction Instrument

    Energy Technology Data Exchange (ETDEWEB)

    CW Stewart; G Chen; JM Alzheimer; PA Meyer

    1998-11-10

    The void fraction instrument (WI) was deployed in Tank 241-SY-101 three times in 1998 to confm and locate the retained gas (void) postulated to be causing the accelerating waste level rise observed since 1995. The design, operation, and data reduction model of the WI are described along with validation testing and potential sources of uncertainty. The test plans, field observations and void measurements are described in detail, including the total gas volume calculations and the gas volume model. Based on 1998 data, the void fraction averaged 0.013 i 0.001 in the mixed slurry and 0.30 ~ 0.04 in the crust. This gives gas volumes (at standard pressure and temperature) of 87 t 9 scm in the slurry and 138 ~ 22 scm in the crust for a total retained gas volume of221 *25 scm. This represents an increase of about 74 scm in the crust and a decrease of about 34 scm in the slurry from 1994/95 results. The overall conclusion is that the gas retention is occurring mainly in the crust layer and there is very little gas in the mixed slurry and loosely settled layers below. New insights on crust behavior are also revealed.

  19. Core design and optimization of high performance low sodium void 1000 MWe heterogeneous oxide LMFBR cores

    Energy Technology Data Exchange (ETDEWEB)

    Barthold, W.P.; Orechwa, Y.; Su, S.F.; Beitel, J.C.; Turski, R.; Lam, P.S.K.; Fuller, E.L.

    1979-01-01

    Radially heterogeneous core configurations are effective means to reduce sodium void reactivity. In general, radially heterogeneous cores can be designed as tightly or loosely coupled cores with center core or center blanket arrangements. Core height, number of core regions and number of fuel pins per assembly are additional variables in an optimization of basic heterogeneous core configurations. An extensive study was carried out to optimize the core configurations for 1000 MWe LMFBRs. All cores were subject to a common set of nuclear, mechanical, and thermal-hydraulic design assumptions. They were restrained by an upper sodium void reactivity limit of $2.50 and a doubling time of approximately 15 to 18 years. The screening and optimization procedures employed lead to two core layouts which were both tightly coupled. A complete nuclear analysis of these two cores (derived from a loosely coupled configuration/derived from a tightly coupled configuration) determined the fissile inventories (4268.4/4213.4 kg at BOEC), burnups (83.90/100.7 MWd/t peak), reactivity swings (0.49/1.8% ..delta..k total), power and flux distributions for different control insertion patterns, the breeding performance (15.7/15.3 yrs CSDT), the safety parameters, such as sodium void reactivity ($2.38/$2.23 at EOEC), isothermal Doppler coefficients for both sodium-in (45.6/46.1 T dk/dT x 10/sup -4/ core at EOEC) and sodium-out conditions (28.6/28.2 T dk/dT x 10/sup -4/ core at EOEC), and the transient behavior which shows very little space-dependence during a 60 cent reactivity step insertion.

  20. US Pilot Study of Lumbar to Sacral Nerve Rerouting to Restore Voiding and Bowel Function in Spina Bifida: 3-Year Experience

    Directory of Open Access Journals (Sweden)

    Kenneth M. Peters

    2014-01-01

    Full Text Available Objective. To report our experience with creating a skin-central nervous system-bladder reflex arc with intradural lumbar to sacral motor root microanastomosis to restore bladder/bowel function in spina bifida patients. Methods. Urinary/bowel changes from baseline to three years were evaluated with questionnaires, voiding diaries, urodynamics (UDS, and renal function studies. Treatment response was defined as CIC ≤ once/day with stable renal function, voiding efficiency > 50%, and no worsening of motor function. Results. Of 13 subjects (9 female, median age 8 years, 3 voided small amounts at baseline, one voided 200 cc (voiding efficiency 32%, 4/13 reported normal bowels, and 2/13 were continent of stool. Postoperatively, all had transient lower extremity weakness; one developed permanent foot drop. Over three years, renal function remained stable and mean maximum cystometric capacity (MCC increased (P=0.0135. In the 10 that returned at 3 years, 7 were treatment responders and 9 had discontinued antimuscarinics, but most still leaked urine. Only 2/8 with baseline neurogenic detrusor overactivity (NDO still had NDO, all 3 with compliance <10 mL/cm H2O had normalized, 7/10 considered their bowels normal, 5/10 were continent of stool, and 8/10 would undergo the procedure again. Conclusion. Lumbar to sacral nerve rerouting can improve elimination in spina bifida patients. This trial is registered with ClinicalTrials.gov NCT00378664.

  1. Mechanical Stress Effects on Electromigration Voiding in a Meandering Test Stripe

    Science.gov (United States)

    Lowry, L. E.; Tai, B. H.; Mattila, J.; Walsh, L. H.

    1993-01-01

    Earlier experimental findings concluded that electromigratin voids in these meandering stripe test structures were not randomly distributed and that void nucleation frequenly occurred sub-surface at the metal/thermal oxide interface.

  2. Idiopathic detrusor sphincter dyssynergia in neurologically normal patients with voiding abnormalities

    DEFF Research Database (Denmark)

    Jørgensen, T M; Djurhuus, J C; Schrøder, H D

    1982-01-01

    Symptomatology and clinical manifestations of detrusor sphincter dyssynergia are described in 23 patients without neurological disease. Their cardinal symptoms were recurrent cystitis, enuresis, frequent voiding, back pain during voiding and anal discomfort. The major objective finding was vesico...

  3. Movements in the void:questions surrounding the assimilation of the Aristotelian plenuum theory in the cosmological vision of Thomas Aquinas

    Directory of Open Access Journals (Sweden)

    Ana María Minecan

    2016-05-01

    Full Text Available This article analizes the main points of the assimilation by Thomas Aquinas of the Aristotle's theory about the void, stressing the elements of agreement and discrd between both authors. It studies the treatment offered by Aquinas to the issue of the displacement in spaces without a resistance medium, the conctact transmission of the movement, the spherical shape of the cosmos, the problem of the supracelestial void and the introduction of a new type of movement attributable solely to the separate spiritual substances

  4. Movements in the void:questions surrounding the assimilation of the Aristotelian plenuum theory in the cosmological vision of Thomas Aquinas

    Directory of Open Access Journals (Sweden)

    Ana María Minecan

    2016-05-01

    Full Text Available This article analizes the main points of the assimilation by Thomas Aquinas of the Aristotle's theory about the void, stressing the elements of agreement and discrd between both authors. It studies the treatment offered by Aquinas to the issue of the displacement in spaces without a resistance medium, the conctact transmission of the movement, the spherical shape of the cosmos, the problem of the supracelestial void and the introduction of a new type of movement attributable solely to the separate spiritual substances

  5. Effect of nonlinear void reactivity on bifurcation characteristics of a lumped-parameter model of a BWR: A study relevant to RBMK

    Energy Technology Data Exchange (ETDEWEB)

    Verma, Dinkar, E-mail: dinkar@iitk.ac.in [Nuclear Engineering and Technology Program, Indian Institute of Technology Kanpur, Kanpur 208 016 (India); Kalra, Manjeet Singh, E-mail: drmanjeet.singh@dituniversity.edu.in [DIT University, Dehradun 248 009 (India); Wahi, Pankaj, E-mail: wahi@iitk.ac.in [Department of Mechanical Engineering, Indian Institute of Technology Kanpur, Kanpur 208 016 (India)

    2017-04-15

    Highlights: • A simplified model with nonlinear void reactivity feedback is studied. • Method of multiple scales for nonlinear analysis and oscillation characteristics. • Second order void reactivity dominates in determining system dynamics. • Opposing signs of linear and quadratic void reactivity enhances global safety. - Abstract: In the present work, the effect of nonlinear void reactivity on the dynamics of a simplified lumped-parameter model for a boiling water reactor (BWR) is investigated. A mathematical model of five differential equations comprising of neutronics and thermal-hydraulics encompassing the nonlinearities associated with both the reactivity feedbacks and the heat transfer process has been used. To this end, we have considered parameters relevant to RBMK for which the void reactivity is known to be nonlinear. A nonlinear analysis of the model exploiting the method of multiple time scales (MMTS) predicts the occurrence of the two types of Hopf bifurcation, namely subcritical and supercritical, leading to the evolution of limit cycles for a range of parameters. Numerical simulations have been performed to verify the analytical results obtained by MMTS. The study shows that the nonlinear reactivity has a significant influence on the system dynamics. A parametric study with varying nominal reactor power and operating conditions in coolant channel has also been performed which shows the effect of change in concerned parameter on the boundary between regions of sub- and super-critical Hopf bifurcations in the space constituted by the two coefficients of reactivities viz. the void and the Doppler coefficient of reactivities. In particular, we find that introduction of a negative quadratic term in the void reactivity feedback significantly increases the supercritical region and dominates in determining the system dynamics.

  6. Effect of initial void shape on ductile failure in a shear field

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2015-01-01

    For voids in a shear field unit cell model analyses have been used to show that ductile failure is predicted even though the stress triaxiality is low or perhaps negative, so that the void volume fraction does not grow during deformation. Here, the effect of the void shape is studied by analyzing...

  7. Elastic–plastic void expansion in near-self-similar shapes

    DEFF Research Database (Denmark)

    Tvergaard, Viggo

    2011-01-01

    For void growth in an elastic–plastic strain hardening material the preferred shape of the void is calculated, dependent on the macroscopic stress state. Axisymmetric cell model analyses are carried out with a very small initial void size relative to the cell dimensions. Large deformations of the...

  8. 42 CFR 457.216 - Treatment of uncashed or canceled (voided) CHIP checks.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 4 2010-10-01 2010-10-01 false Treatment of uncashed or canceled (voided) CHIP... canceled (voided) CHIP checks. (a) Purpose. This section provides rules to ensure that States refund the... section— Canceled (voided) check means an CHIP check issued by a State or fiscal agent that prior to...

  9. The Influence of the Presence of Multiple Voids on the Discharge Patterns in Solid Epoxy Insulation

    DEFF Research Database (Denmark)

    Holbøll, Joachim T.; Henriksen, Mogens; Larsen, Esben

    1996-01-01

    In this paper, partial discharge test results from initial long term testing on samples which contain more voids, when exposed to a high electric stress will be presented. The influence on the discharge patterns, phase- and height-analyses, of such parameter as the number of voids and the void di...

  10. Perineal surface electromyography does not typically demonstrate expected relaxation during normal voiding.

    Science.gov (United States)

    Kirby, Anna C; Nager, Charles W; Litman, Heather J; Fitzgerald, Mary P; Kraus, Stephen; Norton, Peggy; Sirls, Larry; Rickey, Leslie; Wilson, Tracey; Dandreo, Kimberly J; Shepherd, Jonathan; Zimmern, Philippe

    2011-11-01

    To describe perineal surface patch electromyography (EMG) activity during urodynamics (UDS) and compare activity between filling and voiding phases and to assess for a relationship between preoperative EMG activity and postoperative voiding symptoms. 655 women underwent standardized preoperative UDS that included perineal surface EMG prior to undergoing surgery for stress urinary incontinence. Pressure-flow studies were evaluated for abdominal straining and interrupted flow. Quantitative EMG values were extracted from 10 predetermined time-points and compared between fill and void. Qualitative EMG activity was assessed for the percent of time EMG was active during fill and void and for the average amplitude of EMG during fill compared to void. Postoperative voiding dysfunction was defined as surgical revision or catheterization more than 6 weeks after surgery. Fisher's exact test with a 5% two-sided significance level was used to assess differences in EMG activity and postoperative voiding dysfunction. 321 UDS had interpretable EMG studies, of which 131 (41%) had EMG values at all 10 predetermined and annotated time-points. Quantitative and qualitative EMG signals during flow were usually greater than during fill. The prevalence of postoperative voiding dysfunction in subjects with higher preoperative EMG activity during void was not significantly different. Results were similar in the 42 subjects who had neither abdominal straining during void nor interrupted flow. Perineal surface patch EMG did not measure expected pelvic floor and urethral sphincter relaxation during voiding. Preoperative EMG did not predict patients at risk for postoperative voiding dysfunction. Copyright © 2011 Wiley Periodicals, Inc.

  11. Constraining CMB-consistent primordial voids with cluster evolution

    CERN Document Server

    Mathis, H; Griffiths, L M; Kunz, M

    2004-01-01

    Using cosmological simulations, we make predictions for the distribution of clusters in a plausible non-gaussian model where primordial voids nucleated during inflation act together with scale-invariant adiabatic gaussian fluctuations as seeds for the formation of large-scale structure. This model agrees with most recent observations of the anisotropies of the cosmic microwave background (CMB) and can account for the excess of power measured on cluster scales by the Cosmic Background Imager (CBI), the large empty regions apparent in nearby galaxy redshift surveys and the number of giant arcs measured in deep cluster lensing surveys. We show that the z=0 cluster mass function differs from predictions for a standard LCDM cosmology with the same sigma_8. Moreover, as massive clusters also form much earlier in the "void" scenario, we show that integrated number counts of SZ sources and simple statistics of strong lensing can easily falsify this model.

  12. On the void explanation of the Cold Spot

    Science.gov (United States)

    Marcos-Caballero, A.; Fernández-Cobos, R.; Martínez-González, E.; Vielva, P.

    2016-07-01

    The integrated Sachs-Wolfe (ISW) contribution induced on the cosmic microwave background by the presence of a supervoid as the one detected by Szapudi et al. (2015) is reviewed in this letter in order to check whether it could explain the Cold Spot (CS) anomaly. Two different models, previously used for the same purpose, are considered to describe the matter density profile of the void: a top hat function and a compensated profile produced by a Gaussian potential. The analysis shows that, even enabling ellipticity changes or different values for the dark-energy equation of state parameter ω, the ISW contribution due to the presence of the void does not reproduce the properties of the CS.

  13. The ISW imprints of voids and superclusters on the CMB

    Science.gov (United States)

    Hotchkiss, S.; Nadathur, S.; Gottlöber, S.; Iliev, I. T.; Knebe, A.; Watson, W. A.; Yepes, G.

    2016-10-01

    We examine the stacked integrated Sachs-Wolfe (ISW) imprints on the CMB along the lines of sight of voids and superclusters in galaxy surveys, using the Jubilee ISW simulation and mock luminous red galaxy (LRG) catalogues. We show that the expected signal in the concordance \\Lam CDM model is much smaller than the primary anisotropies arising at the last scattering surface and therefore any currently claimed detections of such an imprint cannot be caused by the ISW effect in \\Lam CDM. We look for the existence of such a signal in the Planck CMB using a catalogue of voids and superclusters from the Sloan Digital Sky Survey (SDSS), but find a result completely consistent with \\Lam CDM - i.e., a null detection.

  14. Study on voids of epoxy matrix composites sandwich structure parts

    Science.gov (United States)

    He, Simin; Wen, Youyi; Yu, Wenjun; Liu, Hong; Yue, Cheng; Bao, Jing

    2017-03-01

    Void is the most common tiny defect of composite materials. Porosity is closely related to composite structure property. The voids forming behaviour in the composites sandwich structural parts with the carbon fiber reinforced epoxy resin skins was researched by adjusting the manufacturing process parameters. The composites laminate with different porosities were prepared with the different process parameter. The ultrasonic non-destructive measurement method for the porosity was developed and verified through microscopic examination. The analysis results show that compaction pressure during the manufacturing process had influence on the porosity in the laminate area. Increasing the compaction pressure and compaction time will reduce the porosity of the laminates. The bond-line between honeycomb core and carbon fiber reinforced epoxy resin skins were also analyzed through microscopic examination. The mechanical properties of sandwich structure composites were studied. The optimization process parameters and porosity ultrasonic measurement method for composites sandwich structure have been applied to the production of the composite parts.

  15. Create Your Plate

    Medline Plus

    Full Text Available ... A A A Listen En Español Create Your Plate Create Your Plate is a simple and effective ... and that your options are endless. Create Your Plate! Click on the plate sections below to add ...

  16. Creating Institutional Space for Business Model Innovation

    Science.gov (United States)

    Sheets, Robert; Crawford, Stephen

    2013-01-01

    From college campuses to the halls of Congress, there is broad agreement that higher education is experiencing a major wave of innovation. This article holds that the changes are significant, but that the resulting threats to existing institutions are manageable if key leaders understand them and if institutions adapt to the new environment. The…

  17. Creating a Common Space for Community Engagement

    Science.gov (United States)

    McRae, Heather

    2012-01-01

    The increased interest in community engagement within higher education provides new opportunities for examining the role of university continuing education (UCE) units in relation to their participation in community university partnerships. This article is based on findings from a qualitative study that used a social theory lens to examine the…

  18. Creating sustainable fiscal space for infrastructure

    OpenAIRE

    Ter-Minassian, Teresa; Hughes, Richard; Hajdenberg, Alejandro

    2015-01-01

    A common dilemma facing governments around the world is how to meet the sizeable fiscal costs of providing and maintaining infrastructure networks. Over the past decade, developed and developing countries have looked to fiscal rules, budgetary reforms, tax policy and administration measures, public-private partnerships and other innovative financial instruments to raise additional finance for infrastructure investment. This paper looks at the range of options for raising the financing to meet...

  19. Creating Space Plasma from the Ground

    Science.gov (United States)

    2016-05-12

    Excitation and ionization and calculation of mean free paths and to add conjugate pe flux for the net composite steady state flux (cm-2 s-1 eV-1 str-1), flux...constant typical for Arecibo HF heating experiments. We used an S-20 extended-red photocathode to feed our ASIP II. Key is to use an all sky ...determine the net fraction of energy which through some ensemble of processes will end up carried away as accelerated electrons. i.e. focus on the

  20. Validation uncertainty of MATRA code for subchannel void distributions

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Dae-Hyun; Kim, S. J.; Kwon, H.; Seo, K. W. [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2014-10-15

    To extend code capability to the whole core subchannel analysis, pre-conditioned Krylov matrix solvers such as BiCGSTAB and GMRES are implemented in MATRA code as well as parallel computing algorithms using MPI and OPENMP. It is coded by fortran 90, and has some user friendly features such as graphic user interface. MATRA code was approved by Korean regulation body for design calculation of integral-type PWR named SMART. The major role subchannel code is to evaluate core thermal margin through the hot channel analysis and uncertainty evaluation for CHF predictions. In addition, it is potentially used for the best estimation of core thermal hydraulic field by incorporating into multiphysics and/or multi-scale code systems. In this study we examined a validation process for the subchannel code MATRA specifically in the prediction of subchannel void distributions. The primary objective of validation is to estimate a range within which the simulation modeling error lies. The experimental data for subchannel void distributions at steady state and transient conditions was provided on the framework of OECD/NEA UAM benchmark program. The validation uncertainty of MATRA code was evaluated for a specific experimental condition by comparing the simulation result and experimental data. A validation process should be preceded by code and solution verification. However, quantification of verification uncertainty was not addressed in this study. The validation uncertainty of the MATRA code for predicting subchannel void distribution was evaluated for a single data point of void fraction measurement at a 5x5 PWR test bundle on the framework of OECD UAM benchmark program. The validation standard uncertainties were evaluated as 4.2%, 3.9%, and 2.8% with the Monte-Carlo approach at the axial levels of 2216 mm, 2669 mm, and 3177 mm, respectively. The sensitivity coefficient approach revealed similar results of uncertainties but did not account for the nonlinear effects on the

  1. Analytical Description of Voids in Majumdar-Papapetrou Spacetimes

    CERN Document Server

    Varela, V

    1999-01-01

    We discuss new Majumdar-Papapetrou solutions for the 3+1 Einstein-Maxwell equations, with charged dust acting as the external source of the fields. The solutions satisfy non-linear potential equations which are related to well-known wave equations of 1+1 soliton physics. Although the matter distributions are not localised, they present central structures which may be identified with voids.

  2. The Persistent Percolation of Single-Stream Voids

    CERN Document Server

    Falck, Bridget

    2014-01-01

    We study the nature of voids defined as single-stream regions that have not undergone shell-crossing. We use ORIGAMI to determine the cosmic web morphology of each dark matter particle in a suite of cosmological $N$-body simulations, which explicitly calculates whether a particle has crossed paths with others along multiple sets of axes and does not depend on a parameter or smoothing scale. The theoretical picture of voids is that of expanding underdensities with borders defined by shell-crossing. We find instead that locally underdense single-stream regions are not bounded on all sides by multi-stream regions, thus they percolate, filling the simulation volume; we show that the set of multi-stream particles also percolates. This percolation persists to high resolution, where the mass fraction of single-stream voids is low, because the volume fraction remains high; we speculate on the fraction of collapsed mass in the continuum limit of infinite resolution. By introducing a volume threshold parameter to defin...

  3. Piezoelectric performance of fluor polymer sandwiches with different void structures

    Science.gov (United States)

    Lou, Kexing; Zhang, Xiaoqing; Xia, Zhongfu

    2012-06-01

    Film sandwiches, consisting of two outer layers of fluoroethylenepropylene and one middle layer of patterned porous polytetrafluoroethylene, were prepared by patterning and fusion bonding. Contact charging was conducted to render the films piezoelectric. The critical voltage to trigger air breakdown in the inner voids in the fabricated films was investigated. The piezoelectric d 33 coefficients were measured employing the quasistatic method and dielectric resonance spectrum. The results show that the critical voltage for air breakdown in the inner voids is associated with the void microstructure of the films. For the films with patterning factors of 0%, 25% and 44%, the critical values are 300, 230 and 230 kV/cm, respectively. With an increase in the patterning factor, both the piezoelectric d 33 coefficients determined from the dielectric resonance spectra and those determined from quasistatic measurements increase, which might be due to a decrease in Young's modulus for the films. The nonlinearity of d 33 becomes increasingly obvious as the patterning factor increases.

  4. Pulsed electrical breakdown of a void-filled dielectric

    Science.gov (United States)

    Anderson, R. A.; Lagasse, R. R.; Schroeder, J. L.

    2002-05-01

    We report breakdown strengths in a void-filled dielectric material, epoxy containing 48 vol % hollow glass microballoon filler, which is stressed with unipolar voltage pulses of the order of 10 μs duration. The microballoon voids had mean diameters of approximately 40 μm and contained SO2 gas at roughly 30% atmospheric pressure. This void-filled material displays good dielectric strength (of the order of 100 kV mm-1) under these short-pulse test conditions. Results from a variety of electrode geometries are reported, including arrangements in which the electric stress is highly nonuniform. Conventional breakdown criteria based on mean or peak electric stress do not account for these data. A statistics-based predictive breakdown model is developed, in which the dielectric is divided into independent, microballoon-sized "discharge cells" and the spontaneous discharge of a single cell is presumed to launch full breakdown of the composite. We obtain two empirical parameters, the mean and standard deviation of the spontaneous discharge field, by fitting breakdown data from two electrode geometries having roughly uniform fields but with greatly differing volumes of electrically stressed material. This model accounts for many aspects of our data, including the inherent statistical scatter and the dependence on the stressed volume, and it provides informative predictions with electrode geometries giving highly nonuniform fields. Issues related to computational spatial resolution and cutoff distance are also discussed.

  5. Tomography of integrated circuit interconnect with an electromigration void

    Energy Technology Data Exchange (ETDEWEB)

    Levine, Zachary H. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8410 (United States); Rensselaer Polytechnic Institute, Troy, New York 12180-3590 (United States); Kalukin, Andrew R. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8410 (United States); Kuhn, Markus [Intel Corporation RA1-329, 5200 Northeast Elam Young Parkway, Hillsboro, Oregon 74124 (United States); Frigo, Sean P. [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); McNulty, Ian [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Retsch, Cornelia C. [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Wang, Yuxin [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Arp, Uwe [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8410 (United States); Lucatorto, Thomas B. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8410 (United States); Ravel, Bruce D. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8410 (United States)] (and others)

    2000-05-01

    An integrated circuit interconnect was subject to accelerated-life test conditions to induce an electromigration void. The silicon substrate was removed, leaving only the interconnect test structure encased in silica. We imaged the sample with 1750 eV photons using the 2-ID-B scanning transmission x-ray microscope at the Advanced Photon Source, a third-generation synchrotron facility. Fourteen views through the sample were obtained over a 170 degree sign range of angles (with a 40 degree sign gap) about a single rotation axis. Two sampled regions were selected for three-dimensional reconstruction: one of the ragged end of a wire depleted by the void, the other of the adjacent interlevel connection (or ''via''). We applied two reconstruction techniques: the simultaneous iterative reconstruction technique and a Bayesian reconstruction technique, the generalized Gaussian Markov random field method. The stated uncertainties are total, with one standard deviation, which resolved the sample to 200{+-}70 and 140{+-}30 nm, respectively. The tungsten via is distinguished from the aluminum wire by higher absorption. Within the void, the aluminum is entirely depleted from under the tungsten via. The reconstructed data show the applicability of this technique to three-dimensional imaging of buried defects in submicrometer structures relevant to the microelectronics industry. (c) 2000 American Institute of Physics.

  6. On the Star Formation Properties of Void Galaxies

    CERN Document Server

    Moorman, Crystal M; White, Amanda; Vogeley, Michael S; Hoyle, Fiona; Giovanelli, Riccardo; Haynes, Martha P

    2016-01-01

    We measure the star formation properties of two large samples of galaxies from the SDSS in large-scale cosmic voids on time scales of 10 Myr and 100 Myr, using H$\\alpha$ emission line strengths and GALEX FUV fluxes, respectively. The first sample consists of 109,818 optically selected galaxies. We find that void galaxies in this sample have higher specific star formation rates (SSFRs; star formation rates per unit stellar mass) than similar stellar mass galaxies in denser regions. The second sample is a subset of the optically selected sample containing 8070 galaxies with reliable HI detections from ALFALFA. For the full HI detected sample, SSFRs do not vary systematically with large-scale environment. However, investigating only the HI detected dwarf galaxies reveals a trend towards higher SSFRs in voids. Furthermore, we estimate the star formation rate per unit HI mass (known as the star formation efficiency; SFE) of a galaxy, as a function of environment. For the overall HI detected population, we notice n...

  7. Dwarf Galaxies in Voids: Dark Matter Halos and Gas Cooling

    Directory of Open Access Journals (Sweden)

    Matthias Hoeft

    2010-01-01

    Full Text Available Galaxy surveys have shown that luminous galaxies are mainly distributed in large filaments and galaxy clusters. The remaining large volumes are virtually devoid of luminous galaxies. This is in concordance with the formation of the large-scale structure in the universe as derived from cosmological simulations. However, the numerical results indicate that cosmological voids are abundantly populated with dark matter haloes which may in principle host dwarf galaxies. Observational efforts have in contrast revealed that voids are apparently devoid of dwarf galaxies. We investigate the formation of dwarf galaxies in voids by hydrodynamical cosmological simulations. Due to the cosmic ultraviolet background radiation low-mass haloes show generally a reduced baryon fraction. We determine the characteristic mass below which dwarf galaxies are baryon deficient. We show that the circular velocity below which the accretion of baryons is suppressed is approximately 40 kms−1. The suppressed baryon accretion is caused by the photo-heating due to the UV background. We set up a spherical halo model and show that the effective equation of the state of the gas in the periphery of dwarf galaxies determines the characteristic mass. This implies that any process which heats the gas around dwarf galaxies increases the characteristic mass and thus reduces the number of observable dwarf galaxies.

  8. VOID GROWTH AND CAVITATION IN NONLINEAR VISCOELASTIC SOLIDS

    Institute of Scientific and Technical Information of China (English)

    张赟; 黄筑平

    2003-01-01

    This paper discusses the growth of a pre-existing void in a nonlinear viscoelastic material subjected to remote hydrostatic tensions with different loading rates. The constitutive relation of this viscoelastic material is the one recently proposed by the present authors, which may be considered as a generalization of the non-Gaussian statistical theory in rubber elasticity. As the first order approximation, the above constitutive relation can be reduced to the "neo-Hookean" type viscoelastic one.Investigations of the influences of the material viscosity and the loading rate on the void growth, or on the cavitation are carried out. It is found that: (1) for generalized "inverse Langevin approximation"nonlinear viscoelastic materials, the cavitation limit does not exist, but there is a certain (remote)stress level at which the void will grow rapidly; (2) for generalized "Gaussian statistics" (neo-Hookean type) viscoelastic materials, the cavitation limit exists, and is an increasing function of the loading rate.The present discussions may be of importance in understanding the material failure process under high triaxial stress.

  9. Confirmation of sublunarean voids and thin layering in mare deposits

    Science.gov (United States)

    Robinson, M. S.; Ashley, J. W.; Boyd, A. K.; Wagner, R. V.; Speyerer, E. J.; Ray Hawke, B.; Hiesinger, H.; van der Bogert, C. H.

    2012-08-01

    Typical flow thicknesses of lunar mare basalts were not well constrained in the past, because as craters and rilles age, downslope movement of loose material tends to mix and bury stratigraphy, obscuring the three dimensional nature of the maria. New Lunar Reconnaissance Orbiter Camera high resolution images unambiguously reveal thicknesses of mare basalt layers exposed in impact craters, rilles, and steep-walled pits. Pits up to one hundred meters deep present relatively unmodified, near-vertical sections of mare in three cases, and many young impact craters also expose well preserved sections of mare. Oblique views of each pit and many of these craters reveal multiple layers, 3 to 14 m thick, indicating that eruptions typically produced a series of ˜10 m thick flows (or flow lobes) rather than flows many tens to hundreds of meters thick. Additionally, these images unambiguously show that the floors of two pits extend beneath the mare surfaces, thus revealing sublunarean voids of unknown lateral extent. We also document the occurrence of pits that may be expressions of collapse into subsurface voids in non-mare impact melt deposits. These voids are compelling targets for future human and robotic exploration, with potential as temporary shelters, habitations, or geologic museums.

  10. Enthalpy and void distributions in subchannels of PHWR fuel bundles

    Energy Technology Data Exchange (ETDEWEB)

    Park, J. W.; Choi, H.; Rhee, B. W. [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    Two different types of the CANDU fuel bundles have been modeled for the ASSERT-IV code subchannel analysis. From calculated values of mixture enthalpy and void fraction distribution in the fuel bundles, it is found that net buoyancy effect is pronounced in the central region of the DUPIC fuel bundle when compared with the standard CANDU fuel bundle. It is also found that the central region of the DUPIC fuel bundle can be cooled more efficiently than that of the standard fuel bundle. From the calculated mixture enthalpy distribution at the exit of the fuel channel, it is found that the mixture enthalpy and void fraction can be highest in the peripheral region of the DUPIC fuel bundle. On the other hand, the enthalpy and the void fraction were found to be highest in the central region of the standard CANDU fuel bundle at the exit of the fuel channel. This study shows that the subchannel analysis is very useful in assessing thermal behavior of the fuel bundle that could be used in CANDU reactors. 10 refs., 4 figs., 2 tabs. (Author)

  11. Histological and mechanical evaluation of self-setting calcium phosphate cements in a sheep vertebral bone void model.

    Science.gov (United States)

    Kobayashi, Naomi; Ong, Kevin; Villarraga, Marta; Schwardt, Jeffrey; Wenz, Robert; Togawa, Daisuke; Fujishiro, Takaaki; Turner, A Simon; Seim, Howard B; Bauer, Thomas W

    2007-06-15

    We investigated the histological and compressive properties of three different calcium phosphate cements (CPCs) using a sheep vertebral bone void model. One of the CPCs contained barium sulfate to enhance its radiopacity. Bone voids were surgically created in the lumbar region of 23 ovine spines - L3, L4, and L5 (n = 69 total vertebral bodies) - and the voids were filled with one of the three CPCs. A fourth group consisted of whole intact vertebrae. Histologic evaluation was performed for 30 of the 69 vertebrae 2 or 4 months after surgery along with radiographic evaluation. Compressive testing was performed on 39 vertebrae 4 months after surgery along with micro-CT analysis. All three CPCs were biocompatible and extremely osteoconductive. Osteoclasts associated with adjacent bone formation suggest that each cement can undergo slow resorption and replacement by bone and bone marrow. Compressive testing did not reveal a significant difference in the ultimate strength, ultimate strain, and structural modulus, among the three CPCs and intact whole vertebrae. Micro-CT analysis revealed good osseointegration between all three CPCs and adjacent bone. The barium sulfate did not affect the CPCs biocompatibility or mechanical properties. These results suggest that CPC might be a good alternative to polymethylmethacrylate for selected indications.

  12. Measurements of gas pressure in voids in epoxy castings for high voltage equipment

    DEFF Research Database (Denmark)

    Larsen, Esben; Henriksen, Mogens; Nielsen, E

    1988-01-01

    the partial-discharge inception voltage. Data show that gas pressure in voids in epoxy castings can be determined by use of an ultrasound test method. A relationship between the void gas pressure and the epoxy curing pressure is also found. This investigation is part of an effort to predict the inception......An investigation of samples of epoxy each containing one void, which were produced at different pressures, is reported. The samples were of the disk type with the void located in the center. The gas in the voids has a pressure somewhat related to the curing pressure, thereby directly influencing...

  13. Modelling the void deformation and closure by hot forging of ingot castings

    DEFF Research Database (Denmark)

    Christiansen, Peter; Hattel, Jesper Henri; Kotas, Petr;

    2012-01-01

    After solidification and cooling cast ingots contain voids due to improper feeding and volume shrinkage. Such voids are normally unwanted, so besides of forming the ingot to the desired shape, one of the purposes of the post processing of the ingot by hot forging is to close such voids by mechani......After solidification and cooling cast ingots contain voids due to improper feeding and volume shrinkage. Such voids are normally unwanted, so besides of forming the ingot to the desired shape, one of the purposes of the post processing of the ingot by hot forging is to close such voids...... and focuses on how the voids deform depending on their size and distribution in the ingot as well ashow the forging forces are applied....

  14. Effect of Temperature on the Void Growth in Pure Aluminium at High Strain-Rate Loading

    Institute of Scientific and Technical Information of China (English)

    QI Mei-Lan; HE Hong-Liang; YAN Shi-Lin

    2007-01-01

    @@ With the environment temperature varying from 273K to 773K, the dynamic process of void growth in pure aluminium at high strain-rate loading is calculated based on the dynamic growth equation of a void with internal pressure. The result shows that the effect of temperature on the growth of void should be emphasized. Because the initial pressure of void with gas will increase and the viscosity of materials will decrease with the rising of temperature, the growth of void is accelerated. Furthermore, material inertia restrains the growth of void evidently when the diameter exceeds 10μm. The effect of surface tension is very weak in the whole process of void growth.

  15. Self-similarity and universality of void density profiles in simulation and SDSS data

    CERN Document Server

    Nadathur, S; Diego, J M; Iliev, I T; Gottlöber, S; Watson, W A; Yepes, G

    2014-01-01

    The stacked density profile of cosmic voids in the galaxy distribution provides an important tool for the use of voids for precision cosmology. We study the density profiles of voids identified using the ZOBOV watershed transform algorithm in realistic mock luminous red galaxy (LRG) catalogues from the Jubilee simulation, as well as in void catalogues constructed from the SDSS LRG and Main Galaxy samples. We compare different methods for reconstructing density profiles scaled by the void radius and show that the most commonly used method based on counts in shells and simple averaging is statistically flawed as it underestimates the density in void interiors. We provide two alternative methods that do not suffer from this effect; one based on Voronoi tessellations is also easily able to account from artefacts due to finite survey boundaries and so is more suitable when comparing simulation data to observation. Using this method we show that voids in simulation are exactly self-similar, meaning that their avera...

  16. On the formation of voids in internal tin Nb3Sn superconductors

    CERN Document Server

    Scheuerlein, C; Haibel, A

    2007-01-01

    In this article we describe three void growth mechanisms in Nb3Sn strands of the internal tin design on the basis of combined synchrotron micro-tomography and x-ray diffraction measurements during in-situ heating cycles. Initially void growth is driven by a reduction of void surface area by void agglomeration. The main void volume increase is caused by density changes during the formation of Cu3Sn in the strand. Subsequent transformation of Cu-Sn intermetallics into the lower density a-bronze reduces the void volume again. Long lasting temperature ramps and isothermal holding steps can neither reduce the void volume nor improve the chemical strand homogeneity prior to the superconducting A15 phase nucleation and growth.

  17. Design of capacitance sensor system for void fraction measurement

    Institute of Scientific and Technical Information of China (English)

    LIU Yi-ping; NIU Gang; WANG Jing

    2005-01-01

    Simulation and optimization were applied to a capacitive sensor system based on electrical tomography technology.Sensors, consisting of Morgantown Energy Technology Center (METC) axial synchro driving guard electrodes and two sets of detecting electrodes, make it possible to obtain simultaneously two groups of signals of the void fraction in oil-gas two-phase flow.The computational and experimental results showed that available sensors, charactered by high resolution and fast real-time response can be used for real-time liquid-gas two-phase flow pattern determination.

  18. Void formation in ODS EUROFER produced by hot isostatic pressing

    Energy Technology Data Exchange (ETDEWEB)

    Ortega, Y.; Monge, M.A.; Munoz, A.; Leguey, T.; Pareja, R. [Madrid Univ. Carlos-3, Dept. de Fisica (Spain); Castro, V. de [Oxford Univ., Dept. of Materials (United Kingdom)

    2007-07-01

    for positrons trapped in voids. Unmilled EUROFER and the EUROFER plate did not show this behavior attributed to the formation of voids induced by annealing. The results indicate that the milling damage retained in the HIPed material has the capability to cluster into voids and growth by heating. These voids appear to be stable upon annealing 1323 K. (authors)

  19. Evaluation and Targeted Therapy of Voiding Dysfunction in Children.

    Science.gov (United States)

    Palmer, Lane S

    2016-06-01

    Significant strides have been made over the past two decades in more precisely evaluating and managing children with voiding complaints. A thorough history should offer insight into the possible causes for the presenting complaints and this should be supplemented by physical examination, urine studies, and select imaging. Uroflowmetry and external sphincter electromyography with measurement of postvoid residual urine should allow for accurate diagnosis using categories offered by the International Children's Continence Society. This ability to make an accurate diagnosis should naturally lead to the use of treatment options (urotherapy, pharmacotherapy, biofeedback, and neuromodulation) that specifically target the responsible cause of the complaints rather than simply their symptoms.

  20. Dependence on supernovae light-curve processing in void models

    Energy Technology Data Exchange (ETDEWEB)

    Bengochea, Gabriel R., E-mail: gabriel@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); De Rossi, Maria E., E-mail: derossi@iafe.uba.ar [Instituto de Astronomía y Física del Espacio (IAFE), UBA-CONICET, CC 67, Suc. 28, 1428 Buenos Aires (Argentina); Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

    2014-06-02

    In this work, we show that when supernova Ia (SN Ia) data sets are used to put constraints on the free parameters of inhomogeneous models, certain extra information regarding the light-curve fitter used in the supernovae Ia luminosity fluxes processing should be taken into account. We found that the size of the void as well as other parameters of these models might be suffering extra degenerations or additional systematic errors due to the fitter. A recent proposal to relieve the tension between the results from Planck satellite and SNe Ia is re-analyzed in the framework of these subjects.

  1. Resin flow and void formation in an autoclave cure cycle

    Science.gov (United States)

    Lionetto, Francesca; Lucia, Massimo; Dell'Anna, Riccardo; Maffezzoli, Alfonso

    2016-05-01

    A finite element (FE) model able to evaluate both the evolution of resin flow, degree of reaction and void formation during autoclave cure cycles was developed. The model was implemented using a commercial epoxy matrix widely used in aeronautic field. The FE model also included a kinetic and rheological model whose input parameters were experimentally determined by Differential Scanning Calorimetry and rheological analysis. The FE model was able to predict the evolution of degree of reaction with very good agreement with the experimental data. Moreover, the predicted resin losses were lower than 3% of the overall composite resin content.

  2. Creating Heliophysics Concept Maps

    Science.gov (United States)

    Ali, N. A.; Peticolas, L. M.; Paglierani, R.; Mendez, B. J.

    2011-12-01

    The Center for Science Education at University of California Berkeley's Space Sciences Laboratory is creating concept maps for Heliophysics and would like to get input from scientists. The purpose of this effort is to identify key concepts related to Heliophysics and map their progression to show how students' understanding of Heliophysics might develop from Kindergarten through higher education. These maps are meant to tie into the AAAS Project 2061 Benchmarks for Scientific Literacy and National Science Education Standards. It is hoped that the results of this effort will be useful for curriculum designers developing Heliophysics-related curriculum materials and classroom teachers using Heliophysics materials. The need for concept maps was identified as a result of product analysis undertaken by the NASA Heliophysics Forum Team. The NASA Science Education and Public Outreach Forums have as two of their goals to improve the characterization of the contents of the Science Mission Directorate and Public Outreach (SMD E/PO) portfolio (Objective 2.1) and assist SMD in addressing gaps in the portfolio of SMD E/PO products and project activities (Objective 2.2). An important part of this effort is receiving feedback from solar scientists regarding the inclusion of key concepts and their progression in the maps. This session will introduce the draft concept maps and elicit feedback from scientists.

  3. Testing the imprint of nonstandard cosmologies on void profiles using Monte Carlo random walks

    Science.gov (United States)

    Achitouv, Ixandra

    2016-11-01

    Using Monte Carlo random walks of a log-normal distribution, we show how to qualitatively study void properties for nonstandard cosmologies. We apply this method to an f (R ) modified gravity model and recover the N -body simulation results of [1 I. Achitouv, M. Baldi, E. Puchwein, and J. Weller, Phys. Rev. D 93, 103522 (2016).] for the void profiles and their deviation from GR. This method can potentially be extended to study other properties of the large scale structures such as the abundance of voids or overdense environments. We also introduce a new way to identify voids in the cosmic web, using only a few measurements of the density fluctuations around random positions. This algorithm allows us to select voids with specific profiles and radii. As a consequence, we can target classes of voids with higher differences between f (R ) and standard gravity void profiles. Finally, we apply our void criteria to galaxy mock catalogues and discuss how the flexibility of our void finder can be used to reduce systematic errors when probing the growth rate in the galaxy-void correlation function.

  4. Testing the imprint of non-standard cosmologies on void profiles using Monte Carlo random walks

    CERN Document Server

    Achitouv, Ixandra

    2016-01-01

    Using a Monte Carlo random walks of a log-normal distribution, we show how to qualitatively study void properties for non-standard cosmologies. We apply this method to an f(R) modified gravity model and recover the N-body simulation results of (Achitouv et al. 2016) for the void profiles and their deviation from GR. This method can potentially be extended to study other properties of the large scale structures such as the abundance of voids or overdense environments. We also introduce a new way to identify voids in the cosmic web, using only a few measurements of the density fluctuations around random positions. This algorithm allows to select voids with specific profiles and radii. As a consequence, we can target classes of voids with higher differences between f(R) and standard gravity void profiles. Finally we apply our void criteria to galaxy mock catalogues and discuss how the flexibility of our void finder can be used to reduce systematics errors when probing the growth rate in the galaxy-void correlati...

  5. Nanovoid growth in BCC α-Fe: influences of initial void geometry

    Science.gov (United States)

    Xu, Shuozhi; Su, Yanqing

    2016-12-01

    The growth of voids has a great impact on the mechanical properties of ductile materials by altering their microstructures. Exploring the process of void growth at the nanoscale helps in understanding the dynamic fracture of metals. While some very recent studies looked into the effects of the initial geometry of an elliptic void on the plastic deformation of face-centered cubic metals, a systematic study of the initial void ellipticity and orientation angle in body-centered cubic (BCC) metals is still lacking. In this paper, large scale molecular dynamics simulations with millions of atoms are conducted, investigating the void growth process during tensile loading of metallic thin films in BCC α-Fe. Our simulations elucidate the intertwined influences on void growth of the initial ellipticity and initial orientation angle of the void. It is shown that these two geometric parameters play an important role in the stress-strain response, the nucleation and evolution of defects, as well as the void size/outline evolution in α-Fe thin films. Results suggest that, together with void size, different initial void geometries should be taken into account if a continuum model is to be applied to nanoscale damage progression.

  6. Create Your Plate

    Medline Plus

    Full Text Available ... Planning Meals Diabetes Meal Plans Create Your Plate Gluten Free Diets Meal Planning for Vegetarian Diets Cook ... Create Your Plate Meal Planning for Vegetarian Diets Gluten Free Diets Holiday Meal Planning Cook with Heart- ...

  7. Create Your Plate

    Medline Plus

    Full Text Available ... Planning Meals Diabetes Meal Plans Create Your Plate Gluten Free Diets Meal Planning for Vegetarian Diets Cook ... Create Your Plate Meal Planning for Vegetarian Diets Gluten Free Diets Holiday Meal Planning Cook with Heart- ...

  8. Nuclear data sensitivity and uncertainty assessment of sodium voiding reactivity coefficients of an ASTRID-like sodium fast reactor

    Science.gov (United States)

    Nuria, García-Herranz; Anne-Laurène, Panadero; Ana, Martinez; Sandro, Pelloni; Konstantin, Mikityuk; Andreas, Pautz

    2017-09-01

    The EU 7th Framework ESNII+ project was launched in 2013 with the strategic orientation of preparing ESNII for Horizon 2020. ESNII stands for the European Industrial Initiative on Nuclear Energy, created by the European Commission in 2010 to promote the development of a new generation of nuclear systems in order to provide a sustainable solution to cope with Europe's growing energy needs while meeting the greenhouse gas emissions reduction target. The designs selected by the ESNII+ project are technological demonstrators of Generation-IV systems. The prototype for the sodium cooled fast reactor technology is ASTRID (standing for Advanced Sodium Technological Reactor for Industrial Demonstration), which detailed design phase is foreseen to be initiated in 2019. The ASTRID core has a peculiar design which was created in order to tackle the main neutronic challenge of sodium cooled fast reactors: the inherent overall positive reactivity feedback in case of sodium voiding occurring in the core. Indeed, the core is claimed by its designers to have an overall negative reactivity feedback in this scenario. This feature was demonstrated for an ASTRID-like core within the ESNII+ framework studies performed by nine European institutions. In order to shift the paradigm towards best-estimate plus uncertainties, the nuclear data sensitivity analysis and uncertainty propagation on reactivity coefficients has to be carried out. The goal of this work is to assess the impact of nuclear data uncertainties on sodium voiding reactivity feedback coefficients in order to get a more complete picture of the actual safety margins of the ASTRID low void-core design. The nuclear data sensitivity analysis is performed in parallel using SCALE TSUNAMI-3D and the newly developed GPT SERPENT 2 module. A comparison is carried out between the two methodologies. Uncertainty on the sodium reactivity feedbacks is then calculated using TSAR module of SCALE and the necessary safety margins conclusions

  9. One-Group Perturbation Theory Applied to Measurements with Void

    Energy Technology Data Exchange (ETDEWEB)

    Persson, Rolf

    1966-09-15

    Formulas suitable for evaluating progressive as well as single rod substitution measurements are derived by means of one-group perturbation theory. The diffusion coefficient may depend on direction and position. By using the buckling concept one can derive expressions which are quite simple and the perturbed flux can be taken into account in a comparatively simple way. By using an unconventional definition of cells a transition region is introduced quite logically. Experiments with voids around metal rods, diam. 3.05 cm, have been analysed. The agreement between extrapolated and directly measured buckling values is excellent, the buckling difference between lattices with water-filled and voided shrouds being 0. 263 {+-} 0.015/m{sup 2} and 0.267 {+-} 0.005/m{sup 2} resp. From single-rod experiments differences between diffusion coefficients are determined to {delta}D{sub r}/D = 0.083 {+-} 0.004 and {delta}D{sub z}/D = 0.120 {+-} 0.018. With air-filled shrouds there is consequently anisotropy in the neutron diffusion and we have (D{sub z}/D{sub r}){sub air} = 1.034 {+-} 0.020.

  10. Properties of galaxy halos in Clusters and Voids

    CERN Document Server

    Antonuccio-Delogu, V; Pagliaro, A; Van Kampen, E; Colafrancesco, Sergio; Germaná, A; Gambera, M

    2000-01-01

    We use the results of a high resolution N-body simulation to investigate the role of the environment on the formation and evolution of galaxy-sized halos. Starting from a set of constrained initial conditions, we have produced a final configuration hosting a double cluster in one octant and a large void extending over two octants of the simulation box. In this paper we concentrate on {\\em gravitationally bound} galaxy-sized halos extracted from the two regions. Exploiting the high mass resolution of our simulation ($m_{body} = 2.1\\times 10^{9} h^{-1} M_{\\odot}$), we focus on halos with a relatively small mass: $5\\times 10^{10} \\leq M \\leq 2\\times 10^{12} M_{\\odot}$. We present results for two statistics: the relationship between 1-D velocity dispersion and mass and the probability distribution of the spin parameter $P(\\lambda)$. We do find a clear difference between halos lying in overdense regions and in voids. The \\svm relationship is well described by the Truncated Isothermal Sphere (TIS) model introduced ...

  11. Modeling the Void H I Column Density Spectrum

    CERN Document Server

    Manning, C V

    2003-01-01

    The equivalent width distribution function (EWDF) of \\hone absorbers specific to the void environment has been recently derived (Manning 2002), revealing a large line density of clouds (dN/dz ~500 per unit z for Log (N_HI)> 12.4). I show that the void absorbers cannot be diffuse (or so-called filamentary) clouds, expanding with the Hubble flow, as suggested by N-body/hydro simulations. Absorbers are here modeled as the baryonic remnants of sub-galactic perturbations that have expanded away from their dark halos in response to reionization at z ~ 6.5. A 1-D Lagrangian hydro/gravity code is used to follow the dynamic evolution and ionization structure of the baryonic clouds for a range of halo circular velocities. The simulation products at z=0 can be combined according to various models of the halo velocity distribution function to form a column density spectrum that can be compared with the observed. I find that such clouds may explain the observed EWDF if the halo velocity distribution function is as steep a...

  12. On the linearity of tracer bias around voids

    CERN Document Server

    Pollina, Giorgia; Dolag, Klaus; Weller, Jochen; Baldi, Marco; Moscardini, Lauro

    2016-01-01

    The large-scale structure of the universe can only be observed directly via luminous tracers of the underlying distribution of dark matter. However, the clustering statistics of tracers are biased and depend on various properties of the tracers themselves, such as their host-halo mass and formation and assembly history. On very large scales, where density fluctuations are within the linear regime, this tracer bias results in a constant offset in the clustering amplitude, which is known as linear bias. Towards smaller non-linear scales, this is no longer the case and tracer bias becomes a complicated function of scale and time. We focus on tracer bias centered on cosmic voids, depressions of the density field that spatially dominate the universe. We consider three different types of tracers: galaxies, galaxy clusters and AGNs, extracted from the hydrodynamical simulation suite Magneticum Pathfinder. In contrast to common clustering statistics that focus on the auto-correlation of tracers, we find that void-tra...

  13. Are we living near the center of a local void?

    CERN Document Server

    Cusin, Giulia; Uzan, Jean-Philippe

    2016-01-01

    The properties of the cosmic microwave background (CMB) temperature and polarisation anisotropies measured by a static, off-centered observer located in a local spherically symmetric void, are described. In particular in this paper we compute, together with the standard 2- point angular correlation functions, the off-diagonal correlators, which are no more vanishing by symmetry. While the energy shift induced by the off-centered position of the observer can be suppressed by a proper choice of the observer velocity, a lensing-like effect on the CMB emission point remains. This latter effect is genuinely geometrical (e.g. non-degenerate with a boost) and reflects in the structure of the off-diagonal correlators. At lowest order in this effect, the temperature and polarisation correlation matrices have non-vanishing diagonal elements, as usual, and all the off-diagonal terms are excited. This particular signature of a local void model allows one, in principle, to disentangle geometrical effects from local kinema...

  14. Molecular dynamics study of void effect on nanoimprint of single crystal aluminum

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Ying [Center for Precision Engineering, Harbin Institute of Technology, Harbin (China); Sun Tao, E-mail: spm@hit.edu.cn [Center for Precision Engineering, Harbin Institute of Technology, Harbin (China); Zhang Junjie; Yan Yongda [Center for Precision Engineering, Harbin Institute of Technology, Harbin (China)

    2011-06-01

    Pre-existing defects can alter mechanical behavior of materials significantly under applied load. In current study molecular dynamics (MD) simulations are performed to reveal pre-existing void effect on nanoimprint of single crystal Al thin films, such as deformation mechanism and spring back phenomenon. Current simulation results show void acts as strong barrier to dislocation motion, although plastic deformation is dominantly controlled by dislocation activities. It indicates the void volume fraction has strong influence on nanoimprint: the larger the void volume fraction, the smaller the maximum force required for initial dislocation nucleation, and the stronger the interaction between extended dislocation and void. It also demonstrates that there is a critical void volume fraction for minimum spring back, which is resulted from competition between two roles affecting dislocation annihilation.

  15. Conversion of stacking fault tetrahedra to voids in electron irradiated Fe-Cr-Ni

    Science.gov (United States)

    Kojima, S.; Sano, Y.; Yoshiie, T.; Yoshida, N.; Kiritani, M.

    1986-11-01

    Electron irradiations of the austenitic Fe-13Cr-14Ni alloy were performed with a high voltage electron microscope at temperatures between room temperature and 650 K. Formation of stacking fault tetrahedra, voids and dislocation loops was observed as vacancy clusters. At the lower temperatures, the dominant vacancy clusters were tetrahedra and at the higher temperatures, voids were dominant. In the temperature range at which both tetrahedra and voids were coexistent, conversion of tetrahedra to voids were observed. These results are interpreted as the preferable nucleation of voids at the site of tetrahedra. Local effects of dilatation field at the corner of tetrahedra and the segregation of solute atoms are considered to enhance the nucleation. Clustered defects which are considered to be stacking fault tetrahedra that are formed with D-T fusion neutrons in SUS 316 stainless steel are suggested as the preferable site for void nucleation.

  16. Influence of void ratio on phase change of thermal energy storage for heat pipe receiver

    Directory of Open Access Journals (Sweden)

    Xiaohong Gui

    2015-01-01

    Full Text Available In this paper, influence of void ratio on phase change of thermal storage unit for heat pipe receiver under microgravity is numerically simulated. Accordingly, mathematical model is set up. A solidification-melting model upon the enthalpy-porosity method is specially provided to deal with phase changes. The liquid fraction distribution of thermal storage unit of heat pipe receiver is shown. The fluctuation of melting ratio in PCM canister is indicated. Numerical results are compared with experimental ones in Japan. The results show that void cavity prevents the process of phase change greatly. PCM melts slowly during sunlight periods and freezes slowly during eclipse periods as void ratio increases. The utility ratio of PCM during both sunlight periods and eclipse periods decreases obviously with the improvement of void ratio. The thermal resistance of void cavity is much higher than that of PCM canister wall. Void cavity prevents the heat transfer between PCM zone and canister wall.

  17. Voiding generation in copper interconnect under room temperature storage in 12 years

    Science.gov (United States)

    Matsuyama, Hideya; Suzuki, Takashi; Nakamura, Tomoji; Shiozu, Motoki; Ehara, Hideo; Oshima, Masao; Soeda, Takeshi; Hosoi, Hirokazu; Yamabe, Kikuo

    2017-07-01

    We measured the internal residual stress change of ULSI copper interconnects at room temperature for 12 years to confirm the stress migration phenomenon. The residual stress decreased and voids were generated. Furthermore, we investigated the stress change results and void features obtained through physical analyses. The voids had the same features as those in the high-temperature storage. The estimated volume shrinkage agreed with the total volume of the observed voids, suggesting that void generation causes the decrease in stress. From the obtained result, we conclude that the stress migration degradation phenomenon occurs even at room temperature in the long-term storage, and that the void feature is almost identical to that in the high-temperature acceleration test.

  18. Structure-dependent behavior of stress-induced voiding in Cu interconnects

    Energy Technology Data Exchange (ETDEWEB)

    Wu Zhenyu, E-mail: wuzhenyu@xidian.edu.c [Key Laboratory of Ministry of Education for Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China); Yang Yintang; Chai Changchun; Li Yuejin; Wang Jiayou; Li Bin; Liu Jing [Key Laboratory of Ministry of Education for Band-Gap Semiconductor Materials and Devices, School of Microelectronics, Xidian University, Xi' an 710071 (China)

    2010-05-03

    Stress modeling and cross-section failure analysis by focused-ion-beam have been used to investigate stress-induced voiding phenomena in Cu interconnects. The voiding mechanism and the effect of the interconnect structure on the stress migration have been studied. The results show that the most concentrated tensile stress appears and voids form at corners of vias on top surfaces of Cu M1 lines. A simple model of stress induced voiding in which vacancies arise due to the increase of the chemical potential under tensile stress and diffuse under the force of stress gradient along the main diffusing path indicates that stress gradient rather than stress itself determines the voiding rate. Cu interconnects with larger vias show less resistance to stress-induced voiding due to larger stress gradient at corners of vias.

  19. Shock-induced hotspot formation and chemical reaction initiation in PETN containing a spherical void

    Science.gov (United States)

    Shan, Tzu-Ray; Thompson, Aidan P.

    2014-05-01

    We present results of reactive molecular dynamics simulations of hotspot formation and chemical reaction initiation in shock-induced compression of pentaerythritol tetranitrate (PETN) with the ReaxFF reactive force field. A supported shockwave is driven through a PETN crystal containing a 20 nm spherical void at a sub-threshold impact velocity of 2 km/s. Formation of a hotspot due to shock-induced void collapse is observed. During void collapse, NO2 is the dominant species ejected from the upstream void surface. Once the ejecta collide with the downstream void surface and the hotspot develops, formation of final products such as N2 and H2O is observed. The simulation provides a detailed picture of how void collapse and hotspot formation leads to initiation at sub-threshold impact velocities.

  20. Benchmark of Subchannel Code VIPRE-W with PSBT Void and Temperature Test Data

    Directory of Open Access Journals (Sweden)

    Y. Sung

    2012-01-01

    Full Text Available This paper summarizes comparisons of VIPRE-W thermal-hydraulic subchannel code predictions with measurements of fluid temperature and void from pressurized water reactor subchannel and bundle tests. Using an existing turbulent mixing model, the empirical coefficient derived from code predictions in comparison to the fluid temperature measurement is similar to those from previous mixing tests of similar bundle configurations. The predicted steady-state axial void distributions and time-dependent void profiles based on the Lellouche and Zolotar model generally agree well with the test data. The void model tends to predict lower void at the upper elevation under bulk boiling. The void predictions are in closer agreement with the measurements from the power increase, temperature increase, and flow reduction transients than the depressurization transient. Additional model sensitivity studies showed no significant improvement in the code predictions as compared to the published test data.

  1. The Influence of the Presence of Multiple Voids on the Discharge Patterns in Solid Epoxy Insulation

    DEFF Research Database (Denmark)

    Holbøll, Joachim T.; Henriksen, Mogens; Larsen, Esben

    1996-01-01

    In this paper, partial discharge test results from initial long term testing on samples which contain more voids, when exposed to a high electric stress will be presented. The influence on the discharge patterns, phase- and height-analyses, of such parameter as the number of voids and the void di...... diameters will be given. A first evaluation/opinion of the impact this could have on the estimation of the insulation condition of electrical equipment, based on the identification of PD-patterns, will also be given.......In this paper, partial discharge test results from initial long term testing on samples which contain more voids, when exposed to a high electric stress will be presented. The influence on the discharge patterns, phase- and height-analyses, of such parameter as the number of voids and the void...

  2. Geometric and Chemical Composition Effects on Healing Kinetics of Voids in Mg-bearing Al Alloys

    Science.gov (United States)

    Song, Miao; Du, Kui; Wang, Chunyang; Wen, Shengping; Huang, Hui; Nie, Zuoren; Ye, Hengqiang

    2016-05-01

    The healing kinetics of nanometer-scale voids in Al-Mg-Er and Al-Mg-Zn-Er alloy systems were investigated with a combination of in situ transmission electron microscopy and electron tomography at different temperatures. Mg was observed completely healing the voids, which were then rejuvenated to the alloy composition with further aging, in the Al-Mg-Er alloy. On the contrary, Mg51Zn20 intermetallic compound was formed in voids in the Al-Mg-Zn-Er alloy, which leads to complete filling of the voids but not rejuvenation for the material. For voids with different geometrical aspects, different evolution processes were observed, which are related to the competition between bulk and surface diffusion of the alloys. For voids with a large size difference in their two ends, a viscous flow of surface atoms can be directly observed with in situ electron microscopy, when the size of one end becomes less than tens of nanometers.

  3. VIPRE-W benchmark with PSBT void and temperature test data

    Energy Technology Data Exchange (ETDEWEB)

    Sung, Y.; Oelrich, R.L.; Lee, C.C., E-mail: sungy@westinghouse.com, E-mail: oelricrl@westinghouse.com, E-mail: leecc@westinghouse.com [Westinghouse Electric Co. LLC, Pittsburgh, Pennsylvania (United States); Ruiz-Esquide, N.; Gambetta, M.; Mazufri, C.M., E-mail: nruiz@invap.com.ar, E-mail: gambetta@invap.com.ar, E-mail: mazufri@invap.com.ar [INVAP, San Carlos de Bariloche (Argentina)

    2011-07-01

    This paper summarizes comparisons of VIPRE-W thermal-hydraulic subchannel code predictions with measurements of fluid temperature and void from Pressurized Water Reactor subchannel and bundle tests. Using an existing turbulent mixing model, the empirical coefficient derived from code predictions in comparison to the fluid temperature measurement is similar to those from previous mixing tests of similar bundle configurations. The predicted steady state axial void distributions and time-dependent void profiles based on the Lellouche and Zolotar model generally agree well with the test data. The void model tends to predict lower void at the upper elevation under bulk boiling. The void predictions are in closer agreement with the measurements from the power increase, temperature increase and flow reduction transients than the depressurization transient. (author)

  4. Fuzzy Reasoning to More Accurately Determine Void Areas on Optical Micrographs of Composite Structures

    Science.gov (United States)

    Dominguez, Jesus A.; Tate, Lanetra C.; Wright, M. Clara; Caraccio, Anne

    2013-12-01

    Accomplishing the best-performing composite matrix (resin) requires that not only the processing method but also the cure cycle generate low-void-content structures. If voids are present, the performance of the composite matrix will be significantly reduced. This is usually noticed by significant reductions in matrix-dominated properties, such as compression and shear strength. Voids in composite materials are areas that are absent of the composite components: matrix and fibers. The characteristics of the voids and their accurate estimation are critical to determine for high performance composite structures. One widely used method of performing void analysis on a composite structure sample is acquiring optical micrographs or Scanning Electron Microscope (SEM) images of lateral sides of the sample and retrieving the void areas within the micrographs/images using an image analysis technique. Segmentation for the retrieval and subsequent computation of void areas within the micrographs/images is challenging as the gray-scaled values of the void areas are close to the gray-scaled values of the matrix leading to the need of manually performing the segmentation based on the histogram of the micrographs/images to retrieve the void areas. The use of an algorithm developed by NASA and based on Fuzzy Reasoning (FR) proved to overcome the difficulty of suitably differentiate void and matrix image areas with similar gray-scaled values leading not only to a more accurate estimation of void areas on composite matrix micrographs but also to a faster void analysis process as the algorithm is fully autonomous.

  5. Characterisation of Partial Discharge Pulses in Artificial Voids in Polypropylene Films Used in Capacitors

    OpenAIRE

    B. Ramachandra; Nema, RS

    1996-01-01

    Partial discharges in voids may cause deterioration of solid insulating materials. They often start in voids enclosed in insulation and or at the interface defects. A method of measuring fast discharge pulses with rise times below 1 ns is reported. Characterisation of partial discharge pulses in artificial voids in polypropylene films at atmospheric pressure is analysed that incorporates inception voltage, apparent and real charge, drift velocity and mobility of electrons.

  6. Risk Factors of Voiding Dysfunction and Patient Satisfaction After Tension-free Vaginal Tape Procedure

    OpenAIRE

    2005-01-01

    This study was undertaken to identify risk factors for postoperative voiding dysfunction and factors having impact on patient global satisfaction after a tension-free vaginal tape (TVT) procedure. Two hundred and eighty-five women who underwent the TVT procedure for stress urinary incontinence were analyzed to identify risk factors predictive of voiding dysfunction. Postoperative voiding dysfunction was defined as a peak urinary flow rate (PFR) 30% of bladder capacity (incomplete emptying, n=...

  7. Fuzzy Reasoning to More Accurately Determine Void Areas on Optical Micrographs of Composite Structures

    Science.gov (United States)

    Dominquez, Jesus A.; Tate, Lanetra C.; Wright, M. Clara; Caraccio, Anne

    2013-01-01

    Accomplishing the best-performing composite matrix (resin) requires that not only the processing method but also the cure cycle generate low-void-content structures. If voids are present, the performance of the composite matrix will be significantly reduced. This is usually noticed by significant reductions in matrix-dominated properties, such as compression and shear strength. Voids in composite materials are areas that are absent of the composite components: matrix and fibers. The characteristics of the voids and their accurate estimation are critical to determine for high performance composite structures. One widely used method of performing void analysis on a composite structure sample is acquiring optical micrographs or Scanning Electron Microscope (SEM) images of lateral sides of the sample and retrieving the void areas within the micrographs/images using an image analysis technique. Segmentation for the retrieval and subsequent computation of void areas within the micrographs/images is challenging as the gray-scaled values of the void areas are close to the gray-scaled values of the matrix leading to the need of manually performing the segmentation based on the histogram of the micrographs/images to retrieve the void areas. The use of an algorithm developed by NASA and based on Fuzzy Reasoning (FR) proved to overcome the difficulty of suitably differentiate void and matrix image areas with similar gray-scaled values leading not only to a more accurate estimation of void areas on composite matrix micrographs but also to a faster void analysis process as the algorithm is fully autonomous.

  8. 膨胀土增湿过程中吸力-孔隙比-含水率关系%Relationship among suction, void ratio and water content of expansive soils during wetting process

    Institute of Scientific and Technical Information of China (English)

    辛志宇; 谭晓慧; 王雪; 李芃; 汪贤恩

    2015-01-01

    turning point between saturation and unsaturation parts increases with the initial void ratio, while the suction at this point decreases on the contrary. In the suction−initial void ratio−gravimetric water content (or volumetric water content) coordinate, the soil water characteristic curves that correspond to the specific initial void ratios are plane curves with constant vertical coordinates. However, in the suction−void ratio−gravimetric water content (or volumetric water content) coordinate, the soil water characteristic curves that correspond to the specific initial void ratios are space curves with variable vertical coordinates, which can reflect the influences of both the initial void ratio and the variation of the void ratio during test process.

  9. The void-size effect on plastic flow localization in the Gurson model

    Science.gov (United States)

    Jie, Wen; Yonggang, Huang; Keh-Chih, Hwang

    2004-08-01

    Recent studies have shown that the size of microvoids has a significant effect on the void growth rate. The purpose of this paper is to explore whether the void size effect can influence the plastic flow localization in ductile materials. We have used the extended Gurson's dilatational plasticity theory, which accounts for the void size effect, to study the plastic flow localization in porous solids with long cylindrical voids. The localization model of Rice is adopted, in which the material inside the band may display a different response from that outside the band at the incipient plastic flow localization. The present study shows that it has little effect on the shear band angle.

  10. Extension of the gurson model accounting for the void size effect

    Institute of Scientific and Technical Information of China (English)

    Jie Wen; Keh-Chih Hwang; Yonggang Huang

    2005-01-01

    A continuum model of solids with cylindrical microvoids is proposed based on the Taylor dislocation model.The model is an extension of Gurson model in the sense that the void size effect is accounted for. Beside the void volume fraction f, the intrinsic material length l becomes a parameter representing voids since the void size comes into play in the Gurson model. Approximate yield functions in analytic forms are suggested for both solids with cylindrical microvoids and with spherical microvoids. The application to uniaxial tension curves shows a precise agreement between the approximate analytic yield function and the "exact" parametric form of integrals.

  11. Numerical Simulation of Dust Void Evolution in Complex Plasmas with Ionization Effect

    Institute of Scientific and Technical Information of China (English)

    LIU Yue; WANG Zheng-Xiong; WANG Xiao-Gang

    2006-01-01

    We develop the nonlinear theory of dust voids [Phys. Rev. Lett. 90 (2003) 075001], focusing particularly on effects of the ionization, to investigate numerically the void evolution under cylindrical coordinates [Phys. Plasmas 13(2006) 064502]. The ion velocity profile is solved by a more accurate ion motion equation with the ion convection and ionization terms. It is shown that the differences between the previous result and the one obtained with ionizations are significant for the distributions of the ion and dust velocities, the dust density, and etc., in the void formation process. Furthermore, the ionization can slow down the void formation process effectively.

  12. Influence of ageing, inclusions and voids on ductile fracture mechanism in commercial Al-alloys

    Indian Academy of Sciences (India)

    A Chennakesava Reddy; S Sundar Rajan

    2005-02-01

    The objective of the paper is to study the effect of ageing, inclusions and voids on the mechanism of fracture and resultant toughness. It has been found that the voids are initiated at only a fraction of the larger inclusions present. The initiation of voids at small particles in the ductile fracture process appears to have little effect on fracture toughness. The strain hardening capacity has a marked effect on void size, and is an indicator of fracture toughness in the commercial Al alloy.

  13. The effect of acute increase in urge to void on cognitive function in healthy adults.

    Science.gov (United States)

    Lewis, M S; Snyder, P J; Pietrzak, R H; Darby, D; Feldman, R A; Maruff, P

    2011-01-01

    In healthy adults, voluntary inhibition of micturition is associated with an increasing sensation in the urge to void and pain, and acute pain has been associated with transient deterioration in aspects of cognitive function. Eight healthy young adults consumed 250 ml of water every 15 min until they could no longer inhibit voiding. Performance on standardized measures of cognitive function was measured at hourly intervals which were classified as baseline, when individuals reported an increase in the urge to void, a strong increase in the urge to void, an extreme increase in the urge to void and postmicturition. Sensations of the urge to void and pain increased with time of inhibition of urge to void and with amount of water consumed. Having an extreme urge to void exerted a large negative effect on attentional and working memory functions (d>0.8). These cognitive functions returned to normal levels after micturition. The magnitude of decline in cognitive function associated with an extreme urge to void was as large and equivalent or greater than the cognitive deterioration observed for conditions known to be associated with increased accident risk. Copyright © 2010 Wiley-Liss, Inc.

  14. THE VOID-SIZE EFFECT ON PLASTIC FLOW LOCALIZATION IN THE GURSON MODEL

    Institute of Scientific and Technical Information of China (English)

    WEN Jie; HUANG Yonggang; HWANG Keh-Chih

    2004-01-01

    Recent studies have shown that the size of microvoids has a significant effect on the void growth rate. The purpose of this paper is to explore whether the void size effect can influence the plastic flow localization in ductile materials. We have used the extended Gurson's dilatational plasticity theory, which accounts for the void size effect, to study the plastic flow localization in porous solids with long cylindrical voids. The localization model of Rice is adopted, in which the material inside the band may display a different response from that outside the band at the incipient plastic flow localization. The present study shows that it has little effect on the shear band angle.

  15. The dipole moment of a wall-charged void in a bulk dielectric

    DEFF Research Database (Denmark)

    McAllister, Iain Wilson

    1993-01-01

    The dipole moment of a wall-charged void is examined with reference to the spatial extent of the surface charge density σ and the distribution of this charge. The salient factors influencing the void dipole moment are also examined. From a study of spherical voids, it is shown that, although the σ......-distribution influences the dipole moment, the spatial extent of σ has a greater influence. This behavior is not unexpected. For a void of fixed dimensions, the smaller the charged surface area, the greater is the charges, and thus the greater the dipole moment...

  16. Effect of Contact Conditions on Void Coalescence at Low Stress Triaxiality Shearing

    DEFF Research Database (Denmark)

    Dahl, Jonas; Nielsen, Kim Lau; Tvergaard, Viggo

    2012-01-01

    as contact comes into play during the void collapse. In the early studies of this shear failure mechanism, Tvergaard (2009, "Behaviour of Voids in a Shear Field," Int. J. Fract., 158, pp. 41-49) suggested a pseudo-contact algorithm, using an internal pressure inside the void to resemble frictionless contact......Recent numerical cell-model studies have revealed the ductile failure mechanism in shear to be governed by the interaction between neighboring voids, which collapse to micro-cracks and continuously rotate and elongate until coalescence occurs. Modeling this failure mechanism is by no means trivial...

  17. Constitutive description of casting aluminum alloy based on cylindrical void-cell model

    Institute of Scientific and Technical Information of China (English)

    CHEN Bin; PENG Xiang-he; ZENG Xiang-guo; WU Xin-yan; SUN Shi-tao

    2006-01-01

    Casting aluminum alloys are highly heterogeneous materials with different types of voids that affect the mechanical properties of the material. Through the analysis ora cylindrical void-cell model the evolution equation of the voids was obtained. The evolution equation was embedded into a nonclassical elastoplastic constitutive relation, and an elastoplastic constitutive relation involving void evolution was obtained. A corresponding finite element procedure was developed and applied to the analyses of the distributions of the axial stress and porosity of notched cylindrical specimens of casting aluminum alloy A101. The computed results show good agreement with experimental data.

  18. The effect of voids on the hardening of body-centered cubic Fe

    Science.gov (United States)

    Nakai, Ryosuke; Yabuuchi, Kiyohiro; Nogami, Shuhei; Hasegawa, Akira

    2016-04-01

    The mechanical properties of metals are affected by various types of defects. Hardening is usually described through the interaction between dislocations and obstacles, in the so-called line tension theory. The strength factor in the line tension theory represents the resistance of a defect against the dislocation motion. In order to understand hardening from the viewpoint of the microstructure, an accurate determination of the strength factor of different types of defects is essential. In the present study, the strength factor of voids in body-centered cubic (BCC) Fe was investigated by two different approaches: one based on the Orowan equation to link the measured hardness with the average size and density of voids, and the other involving direct observation of the interaction between dislocations and voids by transmission electron microscope (TEM). The strength factor of voids induced by ion irradiation estimated by the Orowan equation was 0.6, whereas the strength factor estimated by the direct TEM approach was 0.8. The difference in the strength factors measured by the two approaches is due to the positional relationship between dislocations and voids: the central region of a void is stronger than the tip. Moreover, the gliding plane and the direction of dislocation may also affect the strength factor of voids. This study determined the strength factor of voids in BCC Fe accurately, and suggested that the contribution of voids to the irradiation hardening is larger than that of dislocation loops and Cu-rich precipitates.

  19. A Tremella-Like Nanostructure of Silicon@void@graphene-Like Nanosheets Composite as an Anode for Lithium-Ion Batteries.

    Science.gov (United States)

    Mi, Hongwei; Li, Fang; Xu, Shuxian; Li, Ziang; Chai, Xiaoyan; He, Chuanxin; Li, Yongliang; Liu, Jianhong

    2016-12-01

    Graphene coating is receiving discernable attention to overcome the significant challenges associated with large volume changes and poor conductivity of silicon nanoparticles as anodes for lithium-ion batteries. In this work, a tremella-like nanostructure of silicon@void@graphene-like nanosheets (Si@void@G) composite was successfully synthesized and employed as a high-performance anode material with high capacity, cycling stability, and rate capacity. The Si nanoparticles were first coated with a sacrificial SiO2 layer; then, the nitrogen-doped (N-doped) graphene-like nanosheets were formed on the surface of Si@SiO2 through a one-step carbon-thermal method, and the SiO2 layer was removed subsequently to obtain the Si@void@G composite. The performance improvement is mainly attributed to the good conductivity of N-doped graphene-like nanosheets and the unique design of tremella nanostructure, which provides a void space to allow for the Si nanoparticles expanding upon lithiation. The resulting electrode delivers a capacity of 1497.3 mAh g(-1) at the current density of 0.2 A g(-1) after 100 cycles.

  20. Results and applications in thermoelasticity of materials with voids

    Directory of Open Access Journals (Sweden)

    Michele Ciarletta

    1991-05-01

    Full Text Available We consider the linear theory of a thermoelastic porous solid in which the skeletal or matrix is a thermoelastic material and the interstices are void of material. We assume that the initial body is free from stresses. The concept of a distributed body asserts that the mass density at time t has the decomposition γν, where γ is the density of the matrix material and ν (0 In the first part, in order to derive some applications of the reciprocity theorem, we recall some results established by same authors in [3]. Then we obtain integral representations of the solution and prove that the solving of the boundary-initial value problem can be reduced to the solving of an associated uncoupled problem and to an integral equation for the volume fraction field.

  1. A void coalescence model for combined tension and shear

    Science.gov (United States)

    Butcher, C.; Chen, Z. T.

    2009-03-01

    The influence of shear loading on damage development in Gurson-based models has long been neglected resulting in inadequate fracture strain predictions at low triaxiality where shear effects become significant. The plastic limit-load fracture criterion used in advanced Gurson models neglects the influence of shear loading and overestimates the fracture strain and porosity at low triaxiality. In this paper, we extend the recently proposed shear damage model of Xue [1] to provide a stronger physical foundation by removing the simplifying assumptions. Then we directly modify the plastic limit-load fracture criterion by coupling with the extended shear damage model to account for shear weakening and failure of the intervoid ligament in void coalescence. We apply the modified plastic limit-load criterion to predict the necking of sheet tensile specimens and find very good agreement with the available experimental results.

  2. Space-filling polyhedral sorbents

    Science.gov (United States)

    Haaland, Peter

    2016-06-21

    Solid sorbents, systems, and methods for pumping, storage, and purification of gases are disclosed. They derive from the dynamics of porous and free convection for specific gas/sorbent combinations and use space filling polyhedral microliths with facial aplanarities to produce sorbent arrays with interpenetrating interstitial manifolds of voids.

  3. Space space space

    CERN Document Server

    Trembach, Vera

    2014-01-01

    Space is an introduction to the mysteries of the Universe. Included are Task Cards for independent learning, Journal Word Cards for creative writing, and Hands-On Activities for reinforcing skills in Math and Language Arts. Space is a perfect introduction to further research of the Solar System.

  4. Create Your Plate

    Medline Plus

    Full Text Available ... Reset Plate Share Create Your Plate ! Share: Seven Simple Steps to Create Your Plate It's simple and effective for both managing diabetes and losing ... en.html Have Type 2 Diabetes? Our free program will help you live well. More from diabetes. ...

  5. Create Your Plate

    Medline Plus

    Full Text Available ... In Memory In Honor Become a Member En Español Type 1 Type 2 About Us Online Community ... Page Text Size: A A A Listen En Español Create Your Plate Create Your Plate is a ...

  6. Create Your Plate

    Medline Plus

    Full Text Available ... Diabetes Meal Plans Create Your Plate Gluten Free Diets Meal Planning for Vegetarian Diets Cook with Heart-Healthy Foods Holiday Meal Planning ... Planning Meals Diabetes Meal Plans and a Healthy Diet Create Your Plate Meal Planning for Vegetarian Diets ...

  7. Create Your Plate

    Medline Plus

    Full Text Available ... Planning Meals > Create Your Plate Share: Print Page Text Size: A A A Listen En Español Create ... somewhere in between, you have an easy portion control solution that works. Last Reviewed: October 8, 2015 Last Edited: ... Cost of Diabetes Advocate Toolkit Call to Congress Research & ...

  8. Water management issues in the underground gasification of coal and the subsequent use of the voids for long-term carbon dioxide storage

    Energy Technology Data Exchange (ETDEWEB)

    Younger, P.L. [Newcastle Univ., Newcastle Upon Tyne (United Kingdom). Newcastle Inst. for Research on Sustainability; Gonzalez, G. [Newcastle Univ., Newcastle Upon Tyne (United Kingdom). Sir Joseph Swan Inst. for Energy Research; Amezaga, J.M. [Newcastle Univ., Newcastle Upon Tyne (United Kingdom). School of Civil Engineering and Geosciences, Hydrogeochemical Engineering Research and Outreach

    2010-07-01

    A coupled underground coal gasification (UCG) and carbon capture and storage (CCS) technology was discussed. The technologies can be coupled so that voids created by mining can be uses as carbon dioxide (CO{sub 2}) storage sites. UCG involves the in-situ gasification of coal using directionally-drilled wells. The gasification is achieved by spontaneous combustion initiated by the injection of steam and oxygen. The rate of UCG is controlled by varying the availability of oxygen. The syngas produced during the process is drawn to the surface via neighbouring production boreholes where it can then be transported by pipeline for use in range of applications. Voids created by the UCG process will collapse, leaving high permeability zones isolated from the surface by low permeability superincumbent strata. The UCG goaf and relaxed roof strata will have permeabilities 1 to 3 orders of magnitude greater than the permeabilities of deep saline aquifers or hydrocarbon reservoirs. The void volume needed to store the CO{sub 2} produced from the syngas can be 4 or 5 times the volume occupied by the extracted coal. Risks for groundwater arising from UCG are groundwater depletion, contamination, and gas leakage. Prudent site selection and the use of an effective risk assessment framework are needed to ensure the successful implementation of UCG-CCS processes. 11 refs., 2 figs.

  9. Void probability as a function of the void's shape and scale-invariant models. [in studies of spacial galactic distribution

    Science.gov (United States)

    Elizalde, E.; Gaztanaga, E.

    1992-01-01

    The dependence of counts in cells on the shape of the cell for the large scale galaxy distribution is studied. A very concrete prediction can be done concerning the void distribution for scale invariant models. The prediction is tested on a sample of the CfA catalog, and good agreement is found. It is observed that the probability of a cell to be occupied is bigger for some elongated cells. A phenomenological scale invariant model for the observed distribution of the counts in cells, an extension of the negative binomial distribution, is presented in order to illustrate how this dependence can be quantitatively determined. An original, intuitive derivation of this model is presented.

  10. The Natural History and Predictive Factors of Voided Volume in Older Men : The Krimpen Study

    NARCIS (Netherlands)

    van Doorn, Boris; Kok, Esther T.; Blanker, Marco H.; Martens, Edwin P.; Bohnen, Arthur M.; Bosch, J. L. H. Ruud

    Purpose: Although functional bladder capacity, as expressed by maximum voided volume and other frequency-volume chart parameters, are important determinants of lower urinary tract symptoms, to our knowledge no population based data are available on changes in voided volume. We determined changes in

  11. Study of the effect of void surface coatings on radiation-induced swelling

    Energy Technology Data Exchange (ETDEWEB)

    Mansur, L.K.; Wolfer, W.G.

    1977-09-01

    A theoretical investigation has been conducted into the effects on point defect diffusion of the presence of a shell of segregated material about a spherical void. The elastic image interaction of the point defect with the void surrounded by a shell of material of elastic constants which differ from those on the matrix is first computed. The interaction, which depends on the properties of the shell and the dilatation of the defect, results in an energy barrier which must be overcome when the defect diffuses to the void surface. The capture efficiency of the void for the defect is computed for a range of parameters employing this interaction. This capture efficiency is then used directly to obtain predicted effects of segregation on void nucleation and growth under irradiation. It is found that the absorption of the interstitial is reaction controlled at the void. The principal implications are that void nucleation is strongly enhanced and that the kinetics of void growth are altered significantly. Detailed derivations supporting these results are given.

  12. Collapse and coalescence of spherical voids subject to intense shearing: studied in full 3D

    DEFF Research Database (Denmark)

    Nielsen, Kim Lau; Dahl, Jonas; Tvergaard, Viggo

    2012-01-01

    Micro-mechanical 2D cell model studies have revealed ductile failure during intense shearing to be governed by the interaction of neighbouring voids, which collapse to micro-cracks and continuously rotate and elongate until coalescence occurs. For a three-dimensional void structure, this implies...

  13. The lensing and temperature imprints of voids on the Cosmic Microwave Background

    CERN Document Server

    Cai, Yan-Chuan; Mao, Qingqing; Peacock, John A; Szapudi, Istvan; Berlind, Andreas A

    2016-01-01

    We have searched for the signature of cosmic voids in the CMB, in both the Planck temperature and lensing-convergence maps; voids should give decrements in both. We use zobov voids from the DR12 SDSS CMASS galaxy sample. We base our analysis on N-body simulations, to avoid a posteriori bias. For the first time, we detect the signature of voids in CMB lensing: the significance is $4.0\\sigma$, close to $\\Lambda$CDM in both amplitude and projected density-profile shape. A temperature dip is also seen, at modest significance ($1.6\\sigma$), with amplitude about 6 times the prediction. This temperature signal is induced mostly by voids with radius between 100 and 150 Mpc/h, while the lensing signal is mostly contributed by smaller voids -- as expected; lensing relates directly to density, while ISW depends on gravitational potential. The void abundance in observations and simulations agree, as well. We also repeated the analysis excluding lower-significance voids: no lensing signal is detected, with an upper limit ...

  14. On grain size dependent void swelling in pure copper irradiated with fission neutrons

    DEFF Research Database (Denmark)

    Singh, B.N.; Eldrup, Morten Mostgaard; Zinkle, S.J.

    2001-01-01

    in pure copper irradiated with fission neutrons at 623K to a dose level of approx0.3 dpa (displacement peratom). The post-irradiation defect microstructure including voids was investigated using transmission electron microscopy and positron annihilation spectroscopy. The evolution of void swelling...

  15. On grain-size-dependent void swelling in pure copper irradiated with fission neutrons

    DEFF Research Database (Denmark)

    Singh, Bachu Narain; Eldrup, Morten Mostgaard; Zinkle, S.J.

    2002-01-01

    in pure copper irradiated with fission neutrons at 623 K to a dose level of about 0.3 displacement per atom. The post-irradiation defect microstructure including voids was investigated using transmission electron microscopy and positron annihilation spectroscopy. The evolution of void swelling...

  16. The growth and coalescence of ellipsoidal voids in plane strain under combined shear and tension

    NARCIS (Netherlands)

    Scheyvaerts, F.; Onck, P. R.; Tekoglu, C.; Pardoen, T.

    2011-01-01

    New extensions of a model for the growth and coalescence of ellipsoidal voids based on the Gurson formalism are proposed in order to treat problems involving shear and/or voids axis not necessarily aligned with the main loading direction, under plane strain loading conditions. These extensions are m

  17. A molecular dynamics study of void initiation and growth in monocrystalline and nanocrystalline copper

    Science.gov (United States)

    Traiviratana, Sirirat

    MD simulations in monocrystalline and nanocrystalline copper were carried out with LAMMPS to reveal void growth mechanisms. The specimens were subjected to both tensile uniaxial and hydrostatic strains; the results confirm that the emission of (shear) loops is the primary mechanism of void growth. The expansion of the loops and their cross slip leads to the severely work hardened layer surrounding a growing void. Calculations were carried out on voids with different sizes, and a size dependence of the stress response to emitted dislocations was observed, in disagreement with the Gurson model [1] which is scale independent. The growth of voids simulated by MD is compared with the Cocks-Ashby constitutive model and significant agreement is found. The density of geometrically-necessary dislocations as a function of void size is calculated based on the emission of shear loops and their outward propagation. Calculations were also carried out for a void at the interface between two grains sharing a tilt boundary. The results show similar dislocation behaviors. A code that uses Voronoi tessellation for constructing nanocrystalline structures was developed and used to prepare the structures for simulations. Nanocrystal simulations reveal grain sliding and grain rotation as the nanocrystal deformed. Voids were nucleated at grain junctions and grew to coalescence as dislocations accommodated the material transfer. A code that can be used during post-processing to extract useful dislocation information from MD simulation data was partially developed and proved the feasibility of automatically analyzing dislocations.

  18. The Effects of Void on Natural Ventilation Performance in Multi-Storey Housing

    Directory of Open Access Journals (Sweden)

    Fakhriah Muhsin

    2016-08-01

    Full Text Available Enhancing natural ventilation performance in multi-storey housing is very important for the living environment in terms of health and thermal comfort purposes. One of the most important design strategies to enhance natural ventilation in multi-storey housing is through the provision of voids. A void is a passive architectural feature, which is located in the middle of deep plan buildings. It is very crucial to consider the configurations of voids in the buildings for enhancing natural ventilation, especially for multi-storey housing. In this study, Malaysian Medium Cost Multi-Storey Housing (MMCMSH, which is an example of multi-storey housing located in a suburban area, has been selected in this study. This study aims to investigate the potential of void for enhancing natural ventilation performance in multi-storey housing by the comparison of two different void configurations. Field measurement of MMCMSH has been conducted to validate Computational Fluid Dynamic (CFD model and Atmospheric Boundary Layer (ABL is an important parameter for setting up the CFD Model’s domain. Ventilation rate (Q, which is necessary for comfort and health reasons, is an important parameter for the comparison of the different void configurations. This study revealed that the provision of void can enhance natural ventilation performance in multi-storey housing with an increase in the value of Q, from 3.44% to 40.07%, by enlarging the void’s width by 50% compared to the existing void.

  19. A model for void-induced back reaction between radiolytic products in NaCl

    NARCIS (Netherlands)

    Turkin, A.A.; Dubinko, V.I.; Vainshtein, D.I.; Hartog, H.W. den

    2002-01-01

    A kinetic model is formulated for the chemical reaction between radiolytic sodium colloids and gas bubbles, which are brought into contact with each other during the exposure to ionising radiation by the growing voids. The reaction starts with the evaporation of Na atoms into the void due to the loc

  20. An H I survey of the Bootes void .2. The analysis

    NARCIS (Netherlands)

    Szomoru, A; vanGorkom, JH; Gregg, MD; Strauss, MA

    1996-01-01

    We discuss the results of a VLA(2) [Napier et al., Proc. IEEE 71, 1295 (1983)] H I survey of the Bootes void and compare the distribution and H I properties of the void galaxies to those of galaxies found in a survey of regions of mean cosmic density. The Bootes survey covers 1100 Mpc(3), or similar