WorldWideScience

Sample records for planetesimals contributed papers

  1. Abstracts of contributed papers

    Energy Technology Data Exchange (ETDEWEB)

    1994-08-01

    This volume contains 571 abstracts of contributed papers to be presented during the Twelfth US National Congress of Applied Mechanics. Abstracts are arranged in the order in which they fall in the program -- the main sessions are listed chronologically in the Table of Contents. The Author Index is in alphabetical order and lists each paper number (matching the schedule in the Final Program) with its corresponding page number in the book.

  2. Binary Formation in Planetesimal Disks II. Planetesimals with Mass Spectrum

    CERN Document Server

    Kominami, Junko D

    2014-01-01

    Many massive objects have been found in the outer region of the Solar system. How they were formed and evolved has not been well understood, although there have been intensive studies on accretion process of terrestrial planets. One of the mysteries is the existence of binary planetesimals with near-equal mass components and highly eccentric orbits. These binary planetesimals are quite different from the satellites observed in the asteroid belt region. The ratio of the Hill radius to the physical radius of the planetesimals is much larger for the outer region of the disk, compared to the inner region of the disk. The Hill radius increases with the semi major axis. Therefore, planetesimals in the outer region can form close and eccentric binaries, while those in the inner region would simply collide. In this paper, we carried out $N$-body simulations in different regions of the disk and studied if binaries form in the outer region of the disk. We found that large planetesimals tend to form binaries. A signific...

  3. Planetesimals in Debris Disks

    CERN Document Server

    Youdin, Andrew N

    2015-01-01

    Planetesimals form in gas-rich protoplanetary disks around young stars. However, protoplanetary disks fade in about 10 Myr. The planetesimals (and also many of the planets) left behind are too dim to study directly. Fortunately, collisions between planetesimals produce dusty debris disks. These debris disks trace the processes of terrestrial planet formation for 100 Myr and of exoplanetary system evolution out to 10 Gyr. This chapter begins with a summary of planetesimal formation as a prelude to the epoch of planetesimal destruction. Our review of debris disks covers the key issues, including dust production and dynamics, needed to understand the observations. Our discussion of extrasolar debris keeps an eye on similarities to and differences from Solar System dust.

  4. The multifaceted planetesimal formation process

    DEFF Research Database (Denmark)

    Johansen, Anders; Blum, Jürgen; Tanaka, Hidekazu

    2013-01-01

    Accumulation of dust and ice particles into planetesimals is an important step in the planet formation process. Planetesimals are the seeds of both terrestrial planets and the solid cores of gas and ice giants forming by core accretion. Left-over planetesimals in the form of asteroids, trans-Nept...

  5. Collisional evolution of eccentric planetesimal swarms

    CERN Document Server

    Wyatt, M C; Payne, M J; Churcher, L J

    2009-01-01

    Models for the steady state collisional evolution of low eccentricity planetesimal belts identify debris disks with hot dust at 1AU, like eta Corvi and HD69830, as anomalous since collisional processing should have removed most of the planetesimal mass over their >1 Gyr lifetimes. This paper looks at the effect of large planetesimal eccentricities (e>>0.3) on their collisional lifetime and the amount of mass that can remain at late times M_{late}. For an axisymmetric planetesimal disk with common pericentres and eccentricities e, we find that M_{late} \\propto e^{-5/3}(1+e)^{4/3}(1-e)^{-3}. For a scattered disk-like population (i.e., common pericentres), in the absence of dynamical evolution, the mass evolution at late times would be as if only planetesimals with the largest eccentricity were present. Despite the increased remaining mass, higher eccentricities do not increase the hot emission from the collisional cascade until e>0.99, partly because most collisions occur near pericentre thus increasing the dus...

  6. The multifaceted planetesimal formation process

    CERN Document Server

    Johansen, Anders; Tanaka, Hidekazu; Ormel, Chris; Bizzarro, Martin; Rickman, Hans

    2014-01-01

    Accumulation of dust and ice particles into planetesimals is an important step in the planet formation process. Planetesimals are the seeds of both terrestrial planets and the solid cores of gas and ice giants forming by core accretion. Left-over planetesimals in the form of asteroids, trans-Neptunian objects and comets provide a unique record of the physical conditions in the solar nebula. Debris from planetesimal collisions around other stars signposts that the planetesimal formation process, and hence planet formation, is ubiquitous in the Galaxy. The planetesimal formation stage extends from micrometer-sized dust and ice to bodies which can undergo run-away accretion. The latter ranges in size from 1 km to 1000 km, dependent on the planetesimal eccentricity excited by turbulent gas density fluctuations. Particles face many barriers during this growth, arising mainly from inefficient sticking, fragmentation and radial drift. Two promising growth pathways are mass transfer, where small aggregates transfer u...

  7. The multifaceted planetesimal formation process

    DEFF Research Database (Denmark)

    Johansen, Anders; Blum, Jürgen; Tanaka, Hidekazu

    2013-01-01

    Accumulation of dust and ice particles into planetesimals is an important step in the planet formation process. Planetesimals are the seeds of both terrestrial planets and the solid cores of gas and ice giants forming by core accretion. Left-over planetesimals in the form of asteroids, trans...... micrometer-sized dust and ice to bodies which can undergo run-away accretion. The latter ranges in size from 1 km to 1000 km, dependent on the planetesimal eccentricity excited by turbulent gas density fluctuations. Particles face many barriers during this growth, arising mainly from inefficient sticking...

  8. Evolution of planetesimal discs and planets migration

    CERN Document Server

    Popolo, A D; Ercan, E N

    2003-01-01

    In this paper, we further develop the model for the migration of planets introduced in Del Popolo, Gambera and Ercan, and extended to time-dependent planetesimal accretion disks in Del Popolo and Eksi. More precisely, the assumption of Del Popolo and Eksi that the surface density in planetesimals is proportional to that of gas is released. Indeed, the evolution of the radial distribution of solids is governed by many processes: gas-solid coupling, coagulation, sedimentation, evaporation/condensation, so that the distribution of planetesimals emerging from a turbulent disk does not necessarily reflect that of gas. In order to describe this evolution we use a method developed in Stepinski and Valageas which, using a series of simplifying assumptions, is able to simultaneously follow the evolution of gas and solid particles for up to $10^7 {\\rm yr}$. Then, the distribution of planetesimals obtained after $10^7 {\\rm yr}$ is used to study the migration rate of a giant planet through the migration model introduced ...

  9. Tidal disruption of inviscid planetesimals

    Science.gov (United States)

    Boss, A. P.; Cameron, A. G. W.; Benz, W.

    1991-01-01

    In view of previous efforts' demonstration that strongly dissipative planetesimals are immune to tidal disruption, an examination is presently conducted of the complementary case of inviscid planetesimals arising from collisions that are sufficiently energetic to entirely melt the resulting planetesimal and debris. The tidal disruption is numerically simulated by means of the smoothed particle hydrodynamics (SPH) code of Cameron and Benz (1991), concentrating on the tidal disruption of 0.01 earth-mass planetesimals passing by the earth with variations in the impact parameter at perigee and velocity at infinity. The SPH models show that tidal forces during a close encounter can efficiently convert orbital angular momentum into spin angular momentum, thereby initiating equatorial mass-shedding to inviscid planetesimals that have been spun up beyond the limit of rotational stability.

  10. From stellar nebula to planetesimals

    CERN Document Server

    Marboeuf, Ulysse; Alibert, Yann; Cabral, Nahuel; Benz, Willy

    2014-01-01

    Solar and extrasolar comets and extrasolar planets are the subject of numerous studies in order to determine their chemical composition and internal structure. In the case of planetesimals, their compositions are important as they govern in part the composition of future planets. The present works aims at determining the chemical composition of icy planetesimals, believed to be similar to present day comets, formed in stellar systems of solar chemical composition. The main objective of this work is to provide valuable theoretical data on chemical composition for models of planetesimals and comets, and models of planet formation and evolution. We have developed a model that calculates the composition of ices formed during the cooling of the stellar nebula. Coupled with a model of refractory element formation, it allows us to determine the chemical composition and mass ratio of ices to rocks in icy planetesimals throughout in the protoplanetary disc. We provide relationships for ice line positions (for differen...

  11. Planetesimal collisions as a chondrule forming event

    CERN Document Server

    Wakita, Shigeru; Oshino, Shoichi; Hasegawa, Yasuhiro

    2016-01-01

    Chondritic meteorites contain unique spherical materials named chondrules: sub-mm sized silicate grains once melted in a high temperature condition in the solar nebula. We numerically explore one of chondrule forming processes, planetesimal collisions. Previous studies found that impact jetting via protoplanet-planetesimal collisions make chondrules with an amount of 1 % of impactors' mass, when impact velocity exceeds 2.5 km s$^{-1}$. Based on the mineralogical data of chondrules, undifferentiated planetesimals would be more suitable for chondrule-forming collisions than potentially differentiated protoplanets. We examine planetesimal-planetesimal collisions using a shock physics code and find two things: one is that planetesimal-planetesimal collisions produce the nearly same amount of chondrules as protoplanet-planetesimal collisions ($\\sim$ 1 %). The other is that the amount of produced chondrules becomes larger as the impact velocity increases when two planetesimals collide with each other. We also find ...

  12. From Dust To Planetesimal: The Snowball Phase ?

    CERN Document Server

    Xie, Ji-Wei; Thebault, Philippe; Zhou, Ji-Lin; Ge, Jian

    2010-01-01

    The standard model of planet formation considers an initial phase in which planetesimals form from a dust disk, followed by a phase of mutual planetesimal-planetesimal collisions, leading eventually to the formation of planetary embryos. However, there is a potential transition phase (which we call the "snowball phase"), between the formation of the first planetesimals and the onset of mutual collisions amongst them, which has often been either ignored or underestimated in previous studies. In this snowball phase, isolated planetesimals move on Keplerian orbits and grow solely via the direct accretion of sub-cm sized dust entrained with the gas in the protoplanetary disk. Using a simplified model in which planetesimals are progressively produced from the dust, we consider the expected sizes to which the planetesimals can grow before mutual collisions commence and derive the dependence of this size on a number of critical parameters, including the degree of disk turbulence, the planetesimal size at birth and t...

  13. Xenon fractionation in porous planetesimals.

    Science.gov (United States)

    Zahnle, K; Pollack, J B; Kasting, J F

    1990-01-01

    The distinctively fractionated Xe on Mars and Earth may have its root in a common source from which both planets accreted. We begin with Ozima and Nakazawa's hypothesis that terrestrial Xe fractionation was caused by gravitational separation of adsorbed solar nebular gases inside large porous planetesimals. We point out that Xe would have been trapped as the planetesimal grew and pores were squeezed shut by lithostatic pressure. We show that enough fractionated Xe to supply the Earth could have been trapped this way. The degree of fractionation is controlled by the lithostatic pressure at the pore-closing front and so would have been roughly the same for all large planetesimals. The predicted degree of fractionation agrees well with that preserved in terrestrial and martian Xe. Relative to Xe, this source is strongly depleted in other noble gases. In contrast to the original Ozima and Nakazawa hypothesis, our hypothesis predicts the observed fractionation, and it allows planetary accretion to occur after the dissipation of the solar nebula. The required planetesimals are large, representing a class of object now extinct in the solar system.

  14. Planetesimal Compositions in Exoplanet Systems

    CERN Document Server

    Johnson, Torrence V; Lunine, Jonathan I; Madhusudhan, Nikku

    2012-01-01

    We have used recent surveys of the composition of exoplanet host stars to investigate the expected composition of condensed material in planetesimals formed beyond the snow line in the circumstellar nebulae of these systems. Of the major solid forming elements, we find that, as for the Sun, the C and O abundances (and particularly the C/O abundance ratio) have the most significant effect on the composition of icy planetesimals formed in these systems. The calculations use a self-consistent model for the condensation sequence of volatile ices from the nebula gas after refractory (silicate and metal) phases have condensed. The resultant proportions of refractory phases and ices were calculated for a range of nebular temperature structure and redox conditions. Planetesimals in systems with sub-solar C/O should be water ice-rich, with lower than solar mass fractions of refractory materials, while in super-solar C/O systems planetesimals should have significantly higher fractions of refractories, in some cases hav...

  15. The role of pebble fragmentation in planetesimal formation II. Numerical simulations

    CERN Document Server

    Jansson, Karl Wahlberg; Syed, Mohtashim Bukhari; Blum, Jürgen

    2016-01-01

    Some scenarios for planetesimal formation go through a phase of collapse of gravitationally bound clouds of mm-cm-sized pebbles. Such clouds can form for example through the streaming instability in protoplanetary disks. We model the collapse process with a statistical model to obtain the internal structure of planetesimals with solid radii between 10 and 1,000 km. In the collapse, pebbles collide and, depending on relative speed, collisions have different outcomes. A mixture of particle sizes inside a planetesimal leads to better packing capabilities and higher densities. In this paper we apply results from new laboratory experiments of dust aggregate collisions (presented in a companion paper) to model collision outcomes. We find that the internal structure of a planetesimal is strongly dependent on both its mass and the applied fragmentation model. Low-mass planetesimals have no/few fragmenting pebble collisions in the collapse phase and end up as porous pebble-piles. The amount of fragmenting collisions i...

  16. Planetesimal Collisions as a Chondrule Forming Event

    Science.gov (United States)

    Wakita, Shigeru; Matsumoto, Yuji; Oshino, Shoichi; Hasegawa, Yasuhiro

    2017-01-01

    Chondritic meteorites contain unique spherical materials named chondrules: sub-mm sized silicate grains once melted in a high temperature condition in the solar nebula. We numerically explore one of the chondrule forming processes—planetesimal collisions. Previous studies have found that impact jetting via protoplanet–planetesimal collisions can make chondrules with 1% of the impactors’ mass, when the impact velocity exceeds 2.5 km s‑1. Based on the mineralogical data of chondrules, undifferentiated planetesimals would be more suitable for chondrule-forming collisions than potentially differentiated protoplanets. We examine planetesimal–planetesimal collisions using a shock physics code and find two things: one is that planetesimal–planetesimal collisions produce nearly the same amount of chondrules as protoplanet–planetesimal collisions (∼1%). The other is that the amount of produced chondrules becomes larger as the impact velocity increases when two planetesimals collide with each other. We also find that progenitors of chondrules can originate from deeper regions of large targets (planetesimals or protoplanets) than small impactors (planetesimals). The composition of targets is therefore important, to fully account for the mineralogical data of currently sampled chondrules.

  17. The First-Generation Planetesimals

    Science.gov (United States)

    Chiang, Eugene

    The formation of super-km-sized planetesimals from mm-sized grains is a first-rank problem in planet formation. An attractive solution is to bind dust particles together by their collective self-gravity. This scenario requires that dust collect into regions of extraordinary density. We propose a comprehensive suite of numerical simulations using a 3D, fully compressible, multi-phase hydrodynamics code including self-gravity --- a first version of which we have recently assembled and tested successfully --- to help realize the promise of gravitational instability. We focus on the possibility that sub-cm particles collapse by self-gravity to form the first-generation planetesimals. Current particle-particle sticking models, which include fragmentation and bouncing, yield no larger than sub-cm particles -- even in gas disks that are not locally turbulent --- and thus there is a pressing need to develop planetesimal formation pathways that do not rely on the well-known streaming instability, whose relevance diminishes as particles sizes fall below ~1 meter. We will test for ourselves the limits of chemical adhesion using our own high-dynamic-range Monte Carlo coagulation code, applied for the first time to icy particles and augmented with new adaptive binning algorithms, in disks of varying turbulence. Armed with realistic estimates of particle stopping times, we will then deploy our new hydrodynamics code, working in both two-fluid and superparticle modes, to address critical issues in planetesimal formation. How much does turbulent concentration accelerate vertical settling? What are the threshold bulk metallicities required to reach Roche density? How much can drag-assisted gravitational instability enhance local metallicities? And most intriguingly, once dust achieves Roche density, how does the nonlinear development of gravitational instability play out? Our novel hydrodynamical simulations of self-gravitating flows will offer answers to these questions for the

  18. Contribution of Hydrogen Bonds to Paper Strength Properties.

    Directory of Open Access Journals (Sweden)

    Piotr Przybysz

    Full Text Available The objective of this work was to investigate the influence of hydrogen bonds between fibres on static and dynamic strength properties of paper. A commercial bleached pinewood kraft pulp was soaked in water, refined in a PFI, and used to form paper webs in different solvents, such as water, methanol, ethanol, n-propanol and n-butanol, to determine the effect of their dipole moment on static and dynamic strength properties of resulting paper sheets. Paper which was formed in water, being the solvent of the highest dipole moment among the tested ones, showed the highest breaking length and tear resistance. When paper webs were formed in n-butanol, which was the least polar among the solvents, these parameters were reduced by around 75%. These results provide evidence of the importance of water in paper web formation and strong impact of hydrogen bonds between fibres on strength properties of paper.

  19. Efficiency of Planetesimal Ablation in Giant Planetary Envelopes

    CERN Document Server

    Pinhas, Arazi; Clarke, Cathie

    2016-01-01

    Observations of exoplanetary spectra are leading to unprecedented constraints on their atmospheric elemental abundances, particularly O/H, C/H, and C/O ratios. Recent studies suggest that elemental ratios could provide important constraints on formation and migration mechanisms of giant exoplanets. A fundamental assumption in such studies is that the chemical composition of the planetary envelope represents the sum-total of compositions of the accreted gas and solids during the formation history of the planet. We investigate the efficiency with which accreted planetesimals ablate in a giant planetary envelope thereby contributing to its composition rather than sinking to the core. From considerations of aerodynamic drag causing `frictional ablation' and the envelope temperature structure causing `thermal ablation', we compute mass ablations for impacting planetesimals of radii 30 m to 1 km for different compositions (ice to iron) and a wide range of velocities and impact angles, assuming spherical symmetry. I...

  20. The role of planetesimal fragmentation on giant planet formation

    CERN Document Server

    Guilera, O M; Brunini, A; Santamaría, P J

    2014-01-01

    In the standard scenario of planet formation, terrestrial planets and the cores of the giant planets are formed by accretion of planetesimals. As planetary embryos grow the planetesimal velocity dispersion increases due to gravitational excitations produced by embryos. The increase of planetesimal relative velocities causes the fragmentation of them due to mutual collisions. We study the role of planetesimal fragmentation on giant planet formation. We analyze how planetesimal fragmentation modifies the growth of giant planet's cores for a wide range of planetesimal sizes and disk masses. We incorporate a model of planetesimal fragmentation into our model of in situ giant planet formation. We calculate the evolution of the solid surface density (planetesimals plus fragments) due to the accretion by the planet, migration and fragmentation. The incorporation of planetesimal fragmentation significantly modifies the process of planetary formation. If most of the mass loss in planetesimal collisions is distributed ...

  1. Symposium on quantum electronics. Extended abstracts of contributed papers

    Energy Technology Data Exchange (ETDEWEB)

    1981-02-01

    Extended abstracts are provided for papers presented in these subject areas: lasers; quantum optics; nonlinear optics; laser photochemistry; laser spectroscopy; laser scattering; laser produced plasma; and laser applications. (GHT)

  2. Water Fractions in Extrasolar Planetesimals

    CERN Document Server

    Jura, M

    2011-01-01

    With the goal of using externally-polluted white dwarfs to investigate the water fractions of extrasolar planetesimals, we assemble from the literature a sample that we estimate to be more than 60% complete of DB white dwarfs warmer than 13,000 K, more luminous than 3 ${\\times}$ 10$^{-3}$ L$_{\\odot}$ and within 80 pc of the Sun. When considering all the stars together, we find the summed mass accretion rate of heavy atoms exceeds that of hydrogen by over a factor of 1000. If so, this sub-population of extrasolar asteroids treated as an ensemble has little water and is at least a factor of 20 drier than CI chondrites, the most primitive meteorites. In contrast, while an apparent "excess" of oxygen in a single DB can be interpreted as evidence that the accreted material originated in a water-rich parent body, we show that at least in some cases, there can be sufficient uncertainties in the time history of the accretion rate that such an argument may be ambiguous. Regardless of the difficulty associated with int...

  3. Building massive compact planetesimal disks from the accretion of pebbles

    CERN Document Server

    Moriarty, John

    2015-01-01

    We present a model in which planetesimal disks are built from the combination of planetesimal formation and accretion of radially drifting pebbles onto existing planetesimals. In this model, the rate of accretion of pebbles onto planetesimals quickly outpaces the rate of direct planetesimal formation in the inner disk. This allows for the formation of a high mass inner disk without the need for enhanced planetesimal formation or a massive protoplanetary disk. Our proposed mechanism for planetesimal disk growth does not require any special conditions to operate. Consequently, we expect that high mass planetesimal disks form naturally in nearly all systems. The extent of this growth is controlled by the total mass in pebbles that drifts through the inner disk. Anything that reduces the rate or duration of pebble delivery will correspondingly reduce the final mass of the planetesimal disk. Therefore, we expect that low mass stars (with less massive protoplanetary disks), low metallicity stars and stars with gian...

  4. The Interstellar Medium in External Galaxies: Summaries of contributed papers

    Science.gov (United States)

    Hollenbach, David J. (Editor); Thronson, Harley A., Jr. (Editor)

    1990-01-01

    The Second Wyoming Conference entitled, The Interstellar Medium in External Galaxies, was held on July 3 to 7, 1989, to discuss the current understanding of the interstellar medium in external galaxies and to analyze the basic physical processes underlying interstellar phenomena. The papers covered a broad range of research on the gas and dust in external galaxies and focused on such topics as the distribution and morphology of the atomic, molecular, and dust components; the dynamics of the gas and the role of the magnetic field in the dynamics; elemental abundances and gas depletions in the atomic and ionized components; cooling flows; star formation; the correlation of the nonthermal radio continuum with the cool component of the interstellar medium; the origin and effect of hot galactic halos; the absorption line systems seen in distant quasars; and the effect of galactic collisions.

  5. Using asteroid families to test planetesimal differentiation hypotheses

    Science.gov (United States)

    Jacobson, S.; Campins, H.; Delbo', M.; Michel, P.; Tanga, P.; Hanuš, J.; Morbidelli, A.

    2014-07-01

    There have been a series of papers (e.g., Weiss et al. 2008, 2010, 2012; Carporzen et al. 2011; Elkins-Tanton et al. 2011) suggesting that large planetesimals should have metamorphic grading within their crusts and possibly fully-differentiated interiors with mantles and cores. This is a very attractive hypothesis consistent with ideas that planetesimals form as large bodies (Johansen et al. 2007, Cuzzi et al. 2008, Morbidelli et al. 2009) and form early in Solar System history when radioactive heating is still important. It is natural to look to the asteroid belt, our prime reservoir of terrestrial planet building blocks (i.e., left-over planetesimals), for confirmation of this idea. Asteroid families, long known to be the debris from catastrophic disruptions (Hirayama 1918, Michel et al. 2003) conveniently expose the interiors of these left-overs. From simulations of the catastrophic disruption process, we know that not all material is ejected equally. Material near the surface is given higher expulsion velocities and divided into smaller pieces (Michel et al. 2004). Furthermore, while catastrophic disruptions appear to be a messy process, the largest remnants, including those formed by re-accumulation of smaller fragments, come from coherent sections of the progenitor body, although the extent and depth of these sections within the progenitor depend on its internal structure (Michel et al. 2014). This suggests that the ejected material should also maintain a coherent compositional structure (Michel et al., 2004). Therefore, compositional gradients within planetesimals should expose themselves within asteroid families. While all asteroid families share a number of common features, there is a large diversity of membership numbers, progenitor masses, collision energy, formation times, and spectroscopic type and sub-type both between and within families (Zappala et al. 1995, Nesvorny 2012). This compositional diversity allows for a thorough exploration of the

  6. Application of Gas Dynamical Friction for Planetesimals: II. Evolution of Binary Planetesimals

    CERN Document Server

    Grishin, Evgeni

    2015-01-01

    One of first the stages of planet formation is the growth of small planetesimals and their accumulation into large planetesimals and planetary embryos. This early stage occurs much before the dispersal of most of the gas from the protoplanetary disk. At this stage gas-planetesimal interactions play a key role in the dynamical evolution of \\emph{single} intermediate-mass planetesimals ($m_{p}\\sim10^{21}-10^{25}g$) \\emph{through gas dynamical friction} (GDF). A significant fraction of all Solar system planetesimals (asteroids and Kuiper-belt objects) are known to be binary planetesimals (BPs). Here, we explore the effects of GDF on the evolution of \\emph{binary} planetesimals embedded in a gaseous disk using an N-body code with a fiducial external force accounting for GDF. We find that GDF can induce binary mergers on timescales shorter than the disk lifetime for masses above $m_{p}\\gtrsim10^{22}g$ at 1AU, independent of the binary initial separation and eccentricity. Such mergers can affect the structure of me...

  7. The Elemental Compositions of Extrasolar Planetesimals

    CERN Document Server

    Jura, M

    2013-01-01

    Evidence is now compelling that most externally-polluted white dwarfs derive their heavy atoms by accretion from asteroids - the building blocks of rocky planets. Optical and ultraviolet spectroscopy of a small sample of suitable white dwarf stars shows that to zeroth order, the accreted extrasolar parent bodies compositionally resemble bulk Earth. (1) Extrasolar planetesimals are at least 85% by mass composed of O, Mg, Si and Fe. (2) Compared to the Sun, C is often deficient, usually by at least a factor of 10 and therefore comprises less than 1% of an extrasolar planetesimal's mass. At least to-date, C has never been found to be enhanced as would be expected if carbon-rich planetesimals have formed. (3) While there may be individual exceptions, considered as a whole, the population of extrasolar asteroids accreted onto a well-defined sample of local white dwarf stars is less than 1% water by mass.

  8. The effects of ablation on the cross section of planetary envelopes at capturing planetesimals

    Science.gov (United States)

    Benvenuto, Omar G.; Brunini, Adrián

    2008-06-01

    We explore the cross section of giant planet envelopes at capturing planetesimals of different sizes. For this purpose we employ two sets of realistic planetary envelope models (computed assuming for the protoplanetary nebula masses of 10 and 5 times the mass of the minimum mass solar nebula), account for drag and ablation effects and study the trajectories along which planetesimals move. The core accretion of these models has been computed in the oligarchic growth regime [Fortier, A., Benvenuto, O.G., Brunini, A., 2007. Astron. Astrophys. 473, 311-322], which has also been considered for the velocities of the incoming planetesimals. This regime predicts velocities larger that those used in previous studies of this problem. As the rate of ablation is dependent on the third power of velocity, ablation is more important in the oligarchic growth regime. We compute energy and mass deposition, fractional ablated masses and the total cross section of planets for a wide range of values of the critical parameter of ablation. In computing the total cross section of the planet we have included the contributions due to mass deposited by planetesimals moving along unbound orbits. Our results indicate that, for the case of small planetary cores and low velocities for the incoming planetesimals, ablation has a negligible impact on the capture cross section in agreement with the results presented in Inaba and Ikoma [Inaba, S., Ikoma, M., 2003. Astron. Astrophys. 410, 711-723]. However for the case of larger cores and high velocities of the incoming planetesimals as predicted by the oligarchic growth regime, we find that ablation is important in determining the planetary cross section, being several times larger than the value corresponding ignoring ablation. This is so regardless of the size of the incoming planetesimals.

  9. Application of Gas Dynamical Friction for Planetesimals. II. Evolution of Binary Planetesimals

    Science.gov (United States)

    Grishin, Evgeni; Perets, Hagai B.

    2016-04-01

    One of the first stages of planet formation is the growth of small planetesimals and their accumulation into large planetesimals and planetary embryos. This early stage occurs long before the dispersal of most of the gas from the protoplanetary disk. At this stage gas-planetesimal interactions play a key role in the dynamical evolution of single intermediate-mass planetesimals (mp ˜ 1021-1025 g) through gas dynamical friction (GDF). A significant fraction of all solar system planetesimals (asteroids and Kuiper-belt objects) are known to be binary planetesimals (BPs). Here, we explore the effects of GDF on the evolution of BPs embedded in a gaseous disk using an N-body code with a fiducial external force accounting for GDF. We find that GDF can induce binary mergers on timescales shorter than the disk lifetime for masses above mp ≳ 1022 g at 1 au, independent of the binary initial separation and eccentricity. Such mergers can affect the structure of merger-formed planetesimals, and the GDF-induced binary inspiral can play a role in the evolution of the planetesimal disk. In addition, binaries on eccentric orbits around the star may evolve in the supersonic regime, where the torque reverses and the binary expands, which would enhance the cross section for planetesimal encounters with the binary. Highly inclined binaries with small mass ratios, evolve due to the combined effects of Kozai-Lidov (KL) cycles with GDF which lead to chaotic evolution. Prograde binaries go through semi-regular KL evolution, while retrograde binaries frequently flip their inclination and ˜50% of them are destroyed.

  10. APPLICATION OF GAS DYNAMICAL FRICTION FOR PLANETESIMALS. II. EVOLUTION OF BINARY PLANETESIMALS

    Energy Technology Data Exchange (ETDEWEB)

    Grishin, Evgeni; Perets, Hagai B. [Physics Department, Technion—Israel Institute of Technology, Haifa, 3200003 (Israel)

    2016-04-01

    One of the first stages of planet formation is the growth of small planetesimals and their accumulation into large planetesimals and planetary embryos. This early stage occurs long before the dispersal of most of the gas from the protoplanetary disk. At this stage gas–planetesimal interactions play a key role in the dynamical evolution of single intermediate-mass planetesimals (m{sub p} ∼ 10{sup 21}–10{sup 25} g) through gas dynamical friction (GDF). A significant fraction of all solar system planetesimals (asteroids and Kuiper-belt objects) are known to be binary planetesimals (BPs). Here, we explore the effects of GDF on the evolution of BPs embedded in a gaseous disk using an N-body code with a fiducial external force accounting for GDF. We find that GDF can induce binary mergers on timescales shorter than the disk lifetime for masses above m{sub p} ≳ 10{sup 22} g at 1 au, independent of the binary initial separation and eccentricity. Such mergers can affect the structure of merger-formed planetesimals, and the GDF-induced binary inspiral can play a role in the evolution of the planetesimal disk. In addition, binaries on eccentric orbits around the star may evolve in the supersonic regime, where the torque reverses and the binary expands, which would enhance the cross section for planetesimal encounters with the binary. Highly inclined binaries with small mass ratios, evolve due to the combined effects of Kozai–Lidov (KL) cycles with GDF which lead to chaotic evolution. Prograde binaries go through semi-regular KL evolution, while retrograde binaries frequently flip their inclination and ∼50% of them are destroyed.

  11. The Role of Pebble Fragmentation in Planetesimal Formation. II. Numerical Simulations

    Science.gov (United States)

    Wahlberg Jansson, Karl; Johansen, Anders; Bukhari Syed, Mohtashim; Blum, Jürgen

    2017-01-01

    Some scenarios for planetesimal formation go through a phase of collapse of gravitationally bound clouds of millimeter- to centimeter-size pebbles. Such clouds can form, for example, through the streaming instability in protoplanetary disks. We model the collapse process with a statistical model to obtain the internal structure of planetesimals with solid radii between 10 and 1000 km. During the collapse, pebbles collide, and depending on their relative speeds, collisions have different outcomes. A mixture of particle sizes inside a planetesimal leads to better packing capabilities and higher densities. In this paper we apply results from new laboratory experiments of dust aggregate collisions (presented in a companion paper) to model collision outcomes. We find that the internal structure of a planetesimal is strongly dependent on both its mass and the applied fragmentation model. Low-mass planetesimals have no/few fragmenting pebble collisions in the collapse phase and end up as porous pebble piles. The number of fragmenting collisions increases with increasing cloud mass, resulting in wider particle size distributions and higher density. The collapse is nevertheless “cold” in the sense that collision speeds are damped by the high collision frequency. This ensures that a significant fraction of large pebbles survive the collapse in all but the most massive clouds. Our results are in broad agreement with the observed increase in density of Kuiper Belt objects with increasing size, as exemplified by the recent characterization of the highly porous comet 67P/Churyumov–Gerasimenko.

  12. Planetesimals Born Big by Clustering Instability?

    Science.gov (United States)

    Cuzzi, Jeffrey N.; Hartlep, Thomas; Simon, Justin I.; Estrada, Paul R.

    2017-01-01

    Roughly 100km diameter primitive bodies (today's asteroids and TNOs; [1]) are thought to be the end product of so-called "primary accretion". They dominated the initial mass function of planetesimals, and precipitated the onset of a subsequent stage, characterized by runaway gravitational effects, which proceeded onwards to planetary mass objects, some of which accreted massive gas envelopes. Asteroids are the parents of primitive meteorites; meteorite data suggest that asteroids initially formed directly from freelyfloating nebula particles in the mm-size range. Unfortunately, the process by which these primary 100km diameter planetesimals formed remains problematic. We review the most diagnostic primitive parent body observations, highlight critical aspects of the nebula context, and describe the issues facing various primary accretion models. We suggest a path forward that combines current scenarios of "turbulent concentration" (TC) and "streaming instabilities" (SI) into a triggered formation process we call clustering instability (CI). Under expected conditions of nebula turbulence, the success of these processes at forming terrestrial region (mostly silicate) planetesimals requires growth by sticking into aggregates in the several cm size range, at least, which is orders of magnitude more massive than allowed by current growth-by-sticking models using current experimental sticking parameters [2-4]. The situation is not as dire in the ice-rich outer solar system; however, growth outside of the snowline has important effects on growth inside of it [4] and at least one aspect of outer solar system planetesimals (high binary fraction) supports some kind of clustering instability.

  13. Prompt planetesimal formation beyond the snow line

    CERN Document Server

    Armitage, Philip J; Simon, Jacob B

    2016-01-01

    We develop a simple model to predict the radial distribution of planetesimal formation. The model is based on the observed growth of dust to mm-sized particles, which drift radially, pile-up, and form planetesimals where the stopping time and dust-to-gas ratio intersect the allowed region for streaming instability-induced gravitational collapse. Using an approximate analytic treatment, we first show that drifting particles define a track in metallicity--stopping time space whose only substantial dependence is on the disk's angular momentum transport efficiency. Prompt planetesimal formation is feasible for high particle accretion rates (relative to the gas, $\\dot{M}_p / \\dot{M} > 3 \\times 10^{-2}$ for $\\alpha = 10^{-2}$), that could only be sustained for a limited period of time. If it is possible, it would lead to the deposition of a broad and massive belt of planetesimals with a sharp outer edge. Including turbulent diffusion and vapor condensation processes numerically, we find that a modest enhancement of...

  14. Thermal evolution and core formation of planetesimals

    Science.gov (United States)

    Suwa, Taichi; Nagahara, Hiroko

    2017-04-01

    Planetesimals did not get an adequate thermal energy by accretion to form large scale magma ocean because of smaller radii, masses, gravity and accretion energy, however, there are various evidences for the presence of core in planetesimals: 4-Vesta has a core and non-magmatic iron meteorites were segregated metal in bodies that did not experience silicate melting. It has been pointed out that accretion time of planetesimals controls melting and differentiation, because short lived nuclides are plausible heat source. Other factors such as radiative cooling from the surface and thermal conductivity, would also affect thermal evolution of planetesimals. Furthermore, percolation of Fe-S melt through silicate matrix is controlled by the porosity and grain size of silicates and dihedral angle between the melt and silicates. Therefore, the interior structure of planetesimals should be considered by taking the accretion, growth, and thermal evolution of the interior simultaneously. We make a numerical simulation with a spherical 1D model on the basis of the model by Neuman, which is a non-stationary heat conduction equation. We specifically pay attention to the process at temperatures between eutectic temperature Fe-FeS (1213K) and silicate solidus (1425K) and the surface tension of the melt that governs percolation. The model contains three free parameters, formation time, accretion duration, and final size of the planetesimals. The results show that the interior structure can be divided to four types: Type A is undifferentiated, Type B is differentiated to core and mantle of which core was formed by Fe-S melt percolation, Type C is partially differentiated to FeS core and mantle, where mantle retains residual Fe metal, and Type D is differentiated to core and mantle by metal separation in silicate magma. Type A would correspond to the parent bodies of chondrites, and Type B (and Type C?) core would be the source of non-magmatic iron meteorites. Type D would be parent

  15. GLOBAL HIGH-RESOLUTION N-BODY SIMULATION OF PLANET FORMATION. I. PLANETESIMAL-DRIVEN MIGRATION

    Energy Technology Data Exchange (ETDEWEB)

    Kominami, J. D. [Earth-Life Science Institute, Tokyo Institute of Technology, Meguro-Ku, Tokyo (Japan); Daisaka, H. [Hitotsubashi University, Kunitachi-shi, Tokyo (Japan); Makino, J. [RIKEN Advanced Institute for Computational Science, Chuo-ku, Kobe, Hyogo (Japan); Fujimoto, M., E-mail: kominami@mail.jmlab.jp, E-mail: daisaka@phys.science.hit-u.ac.jp, E-mail: makino@mail.jmlab.jp, E-mail: fujimoto.masaki@jaxa.jp [Japan Aerospace Exploration Agency, Sagamihara-shi, Kanagawa (Japan)

    2016-03-01

    We investigated whether outward planetesimal-driven migration (PDM) takes place or not in simulations when the self-gravity of planetesimals is included. We performed N-body simulations of planetesimal disks with a large width (0.7–4 au) that ranges over the ice line. The simulations consisted of two stages. The first-stage simulations were carried out to see the runaway growth phase using the planetesimals of initially the same mass. The runaway growth took place both at the inner edge of the disk and at the region just outside the ice line. This result was utilized for the initial setup of the second-stage simulations, in which the runaway bodies just outside the ice line were replaced by the protoplanets with about the isolation mass. In the second-stage simulations, the outward migration of the protoplanet was followed by the stopping of the migration due to the increase of the random velocity of the planetesimals. Owing to this increase of random velocities, one of the PDM criteria derived in Minton and Levison was broken. In the current simulations, the effect of the gas disk is not considered. It is likely that the gas disk plays an important role in PDM, and we plan to study its effect in future papers.

  16. Recycling of paper: Accounting of greenhouse gases and global warming contributions

    DEFF Research Database (Denmark)

    Merrild, Hanna Kristina; Damgaard, Anders; Christensen, Thomas Højlund

    2009-01-01

    that the GHG contributions from the upstream activities and operational activities, with global warming factors (GWFs) of respectively 1 to 29 and 3 to 9 kg CO2-eq. tonne— 1 paper waste, were small in comparison wih the downstream activities. The GHG contributions from the downstream reprocessing of the paper...

  17. Carbon to oxygen ratios in extrasolar planetesimals

    CERN Document Server

    Wilson, David J; Farihi, Jay; Koester, Detlev

    2016-01-01

    Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting onto white dwarfs, analogous to abundance studies of meteorites. We present measurements of the carbon and oxygen abundances in the debris of planetesimals at ten white dwarfs observed with the Hubble Space Telescope, along with C/O ratios of debris in six systems with previously reported abundances. We find no evidence for carbon-rich planetesimals, with C/O)=-0.92, and oxygen-rich objects with C/O less than or equal to that of the bulk Earth. The latter group may have a higher mass fraction of water than the Earth, increasing their relative oxygen abundance.

  18. EXTRASOLAR REFRACTORY-DOMINATED PLANETESIMALS: AN ASSESSMENT

    Energy Technology Data Exchange (ETDEWEB)

    Jura, M.; Xu, S., E-mail: jura@astro.ucla.edu, E-mail: sxu@astro.ucla.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1562 (United States)

    2013-02-01

    Previously published observations of 60 externally polluted white dwarfs show that none of the stars have accreted from intact refractory-dominated parent bodies composed mainly of Al, Ca, and O, although planetesimals with such a distinctive composition have been predicted to form. We propose that such remarkable objects are not detected by themselves because, unless they are scattered outward from their initial orbit, they are engulfed and destroyed during the star's asymptotic giant branch evolution. As yet, there is at most only weak evidence supporting a scenario where the composition of any extrasolar minor planet can be explained by blending of an outwardly scattered refractory-dominated planetesimal with an ambient asteroid.

  19. Exoplanet Habitability: Effects of Planetesimal Carbon Chemistry

    Science.gov (United States)

    Johnson, Torrence; Mousis, Olivier; Lunine, Jonathan; Madhusudhan, Nikku

    2014-05-01

    We explore the effects of reported differences in C/O values for exoplanet host stars on the composition of planetesimals formed beyond the snow line in these systems. Since the value of C/O in a planet forming nebula has a strong effect on amount of oxygen available for water ice in an oxidizing nebula, exoplanet systems for host stars with C/O greater than the solar value may have planetesimals with very little or no water ice. We have estimated the composition of volatile and refractory material in extrasolar planetesimals using a set of stars with a wide range of measured C/O abundances (Johnson et al. ApJ. 757(2), 192, 2012). The volatile ice content of planetesimals in these systems varies significantly with C/O, controlled primarily by the availability of O for H2O ice condensation. Systems with C/O less than the solar value (C/O = 0.55) should have very water ice rich planetesimals, while water ice mass fraction decreases rapidly with increasing C/O until only ices of CO and CO2 are left in significant proportions. If a significant fraction of C is in the form of refractory CHON particles, C and O are removed from the gas phase and the condensates for super-solar C/O values will be water-poor mixtures of silicates and metal, carbon, and carbon-bearing volatile ices, depending on temperature. For very carbon-rich systems, oxidizing conditions cannot be sustained beyond about C/O=1, due to the oxygen sequestered in solid silicates, oxides and CHON, for refractory C fractions within the Pollack et al. range of 0.4 - 0.7 (ApJ. 421, 615, 1994). These results have implications for assessing the habitability of exoplanets since they constrain the amount of water available beyond the snow line for dynamical delivery to inner planets, depending on the host star's C/O in the circumstellar nebula. Thus one the key chemical ingredients for habitability may be in short supply in carbon-rich, oxygen-poor systems even if planets exist in the 'habitable zone'. TVJ

  20. Meteorites and the RNA World: A Thermodynamic Model of Nucleobase Synthesis within Planetesimals.

    Science.gov (United States)

    Pearce, Ben K D; Pudritz, Ralph E

    2016-11-01

    The possible meteorite parent body origin of Earth's pregenetic nucleobases is substantiated by the guanine (G), adenine (A), and uracil (U) measured in various meteorites. Cytosine (C) and thymine (T), however, are absent in meteorites, making the emergence of an RNA and later RNA/DNA/protein world problematic. We investigated the meteorite parent body (planetesimal) origin of all nucleobases by computationally modeling 18 reactions that potentially contribute to nucleobase formation in such environments. Out of this list, we identified the two most important reactions for each nucleobase and found that these involve small molecules such as HCN, CO, NH3, and water that ultimately arise from the protoplanetary disks in which planetesimals are built. The primary result of this study is that cytosine is unlikely to persist within meteorite parent bodies due to aqueous deamination. Thymine has a thermodynamically favorable reaction pathway from uracil, formaldehyde, and formic acid but likely did not persist within planetesimals containing H2O2 due to an oxidation reaction with this molecule. Finally, while Fischer-Tropsch (FT) synthesis is found to be the dominant source of nucleobases within our model planetesimal, non-catalytic (NC) synthesis may still be significant under certain chemical conditions (e.g., within CR2 parent bodies). We discuss several major consequences of our results for the origin of the RNA world. Key Words: Astrobiology-Cosmochemistry-Meteorites-RNA world-Abiotic organic synthesis. Astrobiology 16, 853-872.

  1. Meteorites and the RNA World: A Thermodynamic Model of Nucleobase Synthesis within Planetesimals

    Science.gov (United States)

    Pearce, Ben K. D.; Pudritz, Ralph E.

    2016-11-01

    The possible meteorite parent body origin of Earth's pregenetic nucleobases is substantiated by the guanine (G), adenine (A), and uracil (U) measured in various meteorites. Cytosine (C) and thymine (T), however, are absent in meteorites, making the emergence of an RNA and later RNA/DNA/protein world problematic. We investigated the meteorite parent body (planetesimal) origin of all nucleobases by computationally modeling 18 reactions that potentially contribute to nucleobase formation in such environments. Out of this list, we identified the two most important reactions for each nucleobase and found that these involve small molecules such as HCN, CO, NH3, and water that ultimately arise from the protoplanetary disks in which planetesimals are built. The primary result of this study is that cytosine is unlikely to persist within meteorite parent bodies due to aqueous deamination. Thymine has a thermodynamically favorable reaction pathway from uracil, formaldehyde, and formic acid but likely did not persist within planetesimals containing H2O2 due to an oxidation reaction with this molecule. Finally, while Fischer-Tropsch (FT) synthesis is found to be the dominant source of nucleobases within our model planetesimal, non-catalytic (NC) synthesis may still be significant under certain chemical conditions (e.g., within CR2 parent bodies). We discuss several major consequences of our results for the origin of the RNA world.

  2. Planetesimal accretion in binary star systems

    CERN Document Server

    Marzari, Francesco; Scholl, Hans

    2007-01-01

    Numerical simulations of planetesimal accretion in circumprimary and circumbinary orbits are described. The secular perturbations by the com- panion star and gas drag are included in our models. We derive limits on the parameters of the binary system for which accretion and then planetary forma- tion are possible. In the circumbinary case we also outline the radial distance from the baricenter of the stars beyond which accumulation always occurs. Hy- drodynamical simulations are also presented to validate our N-body approach based on the axisymmetric approximation for the gas of the disk.

  3. Oligarchic planetesimal accretion and giant planet formation

    CERN Document Server

    Fortier, A; Brunini, A

    2007-01-01

    Aims. In the context of the core instability model, we present calculations of in situ giant planet formation. The oligarchic growth regime of solid protoplanets is the model adopted for the growth of the core. Methods. The full differential equations of giant planet formation were numerically solved with an adaptation of a Henyey-type code. The planetesimals accretion rate was coupled in a self-consistent way to the envelope's evolution. Results. We performed several simulations for the formation of a Jupiter-like object by assuming various surface densities for the protoplanetary disc and two different sizes for the accreted planetesimals. We find that the atmospheric gas drag gives rise to a major enhancement on the effective capture radius of the protoplanet, thus leading to an average timescale reduction of 30% -- 55% and ultimately to an increase by a factor of 2 of the final mass of solids accreted as compared to the situation in which drag effects are neglected. With regard to the size of accreted pla...

  4. Initial mass function of planetesimals formed by the streaming instability

    CERN Document Server

    Schäfer, Urs; Johansen, Anders

    2016-01-01

    The streaming instability is a mechanism to concentrate solid particles into overdense filaments that undergo gravitational collapse and form planetesimals. However, it remains unclear how the initial mass function of these planetesimals depends on the box dimensions of numerical simulations. To resolve this, we perform simulations of planetesimal formation with the largest box dimensions to date, allowing planetesimals to form simultaneously in multiple filaments that can only emerge within such large simulation boxes. In our simulations planetesimals with sizes between 80 km and several hundred kilometers form. We find that a power law with a rather shallow exponential cutoff at the high-mass end represents the cumulative birth mass function better than an integrated power law. The steepness of the exponential cutoff is largely independent of box dimensions and resolution, while the exponent of the power law is not constrained at the resolutions we employ. Moreover, we find that the characteristic mass scal...

  5. On the growth of pebble-accreting planetesimals

    CERN Document Server

    Visser, Rico G

    2015-01-01

    Pebble accretion is a new mechanism to quickly grow the cores of planets. In pebble accretion, gravity and gas drag conspire to yield large collisional cross sections for small particles in protoplanetary disks. However, before pebble accretion commences, aerodynamical deflection may act to prevent planetesimals from becoming large, because particles tend to follow gas streamlines. We derive the planetesimal radius where pebble accretion is initiated and determine the growth timescales of planetesimals by sweepup of small particles. We obtain the collision efficiency factor as the ratio of the numerically-obtained collisional cross section to the planetesimal surface area, from which we obtain the growth timescales. Integrations are conducted in the potential flow limit (steady, inviscid) and in the Stokes flow regime (steady, viscid). Only particles of stopping time $t_s \\ll t_X$ where $t_X\\approx10^3$ s experience aerodynamic deflection. Even in that case, the planetesimal's gravity always ensures positive ...

  6. Papers

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    The chapters in this Volume 7 of a series of PAPERS are based on papers published in the period 2004 - 2008 authored/co-authored by Palle Thoft-Christensen......The chapters in this Volume 7 of a series of PAPERS are based on papers published in the period 2004 - 2008 authored/co-authored by Palle Thoft-Christensen...

  7. Papers

    DEFF Research Database (Denmark)

    Thoft-Christensen, Palle

    The chapters in this Volume 7 of a series of PAPERS are based on papers published in the period 2004 - 2008 authored/co-authored by Palle Thoft-Christensen......The chapters in this Volume 7 of a series of PAPERS are based on papers published in the period 2004 - 2008 authored/co-authored by Palle Thoft-Christensen...

  8. Detectability of Planetesimal Impacts on Giant Exoplanets

    CERN Document Server

    Flagg, Laura; Matthews, Keith

    2015-01-01

    The detectability of planetesimal impacts on imaged exoplanets can be measured using Jupiter during the 1994 comet Shoemaker-Levy 9 events as a proxy. By integrating the whole planet flux with and without impact spots, the effect of the impacts at wavelengths from 2 - 4 microns is revealed. Jupiter's reflected light spectrum in the near-infrared is dominated by its methane opacity including a deep band at 2.3 microns. After the impact, sunlight that would have normally been absorbed by the large amount of methane in Jupiter's atmosphere was instead reflected by the cometary material from the impacts. As a result, at 2.3 microns, where the planet would normally have low reflectivity, it brightened substantially and stayed brighter for at least a month.

  9. Dust Evolution and the Formation of Planetesimals

    CERN Document Server

    Birnstiel, T; Johansen, A

    2016-01-01

    The solid content of circumstellar disks is inherited from the interstellar medium: dust particles of at most a micrometer in size. Protoplanetary disks are the environment where these dust grains need to grow at least 13 orders of magnitude in size. Our understanding of this growth process is far from complete, with different physics seemingly posing obstacles to this growth at various stages. Yet, the ubiquity of planets in our galaxy suggests that planet formation is a robust mechanism. This chapter focuses on the earliest stages of planet formation, the growth of small dust grains towards the gravitationally bound "planetesimals", the building blocks of planets. We will introduce some of the key physics involved in the growth processes and discuss how they are expected to shape the global behavior of the solid content of disks. We will consider possible pathways towards the formation of larger bodies and conclude by reviewing some of the recent observational advances in the field.

  10. Erosion and the limits to planetesimal growth

    CERN Document Server

    Krijt, Sebastiaan; Dominik, Carsten; Tielens, Alexander G G M

    2014-01-01

    The coagulation of microscopic dust into planetesimals is the first step towards planet formation. The size and shape of the growing aggregates determine the efficiency of this early growth. It has been proposed that fluffy ice aggregates can grow very efficiently, suffering less from the bouncing and radial drift barriers. While the collision velocity between icy aggregates of similar size is thought to stay below the fragmentation threshold, they may nonetheless lose mass from collisions with much smaller projectiles. We investigate the effect of these erosive collisions on the ability of porous ice aggregates to cross the radial drift barrier. We develop a Monte Carlo code that calculates the evolution of the growing aggregates, while resolving the entire mass distribution at all times. The aggregate's porosity is treated independently of its mass, and is determined by collisions, gas compaction, and eventually self-gravity compaction. For erosion threshold velocities of 20-40 m/s, high-velocity collisions...

  11. Fragmentation of colliding planetesimals with water content

    CERN Document Server

    Maindl, Thomas I; Schäfer, Christoph; Speith, Roland

    2014-01-01

    We investigate the outcome of collisions of Ceres-sized planetesimals composed of a rocky core and a shell of water ice. These collisions are not only relevant for explaining the formation of planetary embryos in early planetary systems, but also provide insight into the formation of asteroid families and possible water transport via colliding small bodies. Earlier studies show characteristic collision velocities exceeding the bodies' mutual escape velocity which - along with the distribution of the impact angles - cover the collision outcome regimes 'partial accretion', 'erosion', and 'hit-and-run' leading to different expected fragmentation scenarios. Existing collision simulations use bodies composed of strengthless material; we study the distribution of fragments and their water contents considering the full elasto-plastic continuum mechanics equations also including brittle failure and fragmentation.

  12. Rapid planetesimal formation in turbulent circumstellar discs

    CERN Document Server

    Johansen, Anders; Mac Low, Mordecai-Mark; Klahr, Hubert; Henning, Thomas; Youdin, Andrew

    2007-01-01

    The initial stages of planet formation in circumstellar gas discs proceed via dust grains that collide and build up larger and larger bodies (Safronov 1969). How this process continues from metre-sized boulders to kilometre-scale planetesimals is a major unsolved problem (Dominik et al. 2007): boulders stick together poorly (Benz 2000), and spiral into the protostar in a few hundred orbits due to a head wind from the slower rotating gas (Weidenschilling 1977). Gravitational collapse of the solid component has been suggested to overcome this barrier (Safronov 1969, Goldreich & Ward 1973, Youdin & Shu 2002). Even low levels of turbulence, however, inhibit sedimentation of solids to a sufficiently dense midplane layer (Weidenschilling & Cuzzi 1993, Dominik et al. 2007), but turbulence must be present to explain observed gas accretion in protostellar discs (Hartmann 1998). Here we report the discovery of efficient gravitational collapse of boulders in locally overdense regions in the midplane. The bou...

  13. Kozai effect on planetesimal accretion in highly inclined binaries

    Directory of Open Access Journals (Sweden)

    Zhou J.-L.

    2011-07-01

    Full Text Available Planet formation in highly inclined binaries is a complex issue. The Kozai mechanism plays an important role in this situation, since it will lead to high eccentricity and high relative impact velocity of planetesimals, thus hinder the planetesimal accretion. However, as we will show here, the presence of gas disk in some circumstance will suppress the Kozai effect by increasing the apsidal precession rate of the planetesimals, which increases the critical inclination. A criterion of the disk mass above which Kozai effect will not occur is given.

  14. Meteorites and the RNA World: A Thermodynamic Model of Nucleobase Synthesis within Planetesimals

    CERN Document Server

    Pearce, Ben K D

    2016-01-01

    The possible meteorite parent body origin of Earth's pregenetic nucleobases is substantiated by the guanine (G), adenine (A) and uracil (U) measured in various meteorites. Cytosine (C) and thymine (T) however are absent in meteorites, making the emergence of a RNA and later RNA/DNA/protein world problematic. We investigate the meteorite parent body (planetesimal) origin of all nucleobases by computationally modeling 18 reactions that potentially contribute to nucleobase formation in such environments. Out of this list, we identify the two most important reactions for each nucleobase and find that these involve small molecules such as HCN, CO, NH3, and water that ultimately arise from the protoplanetary disks in which planetesimals are built. The primary result of this study is that cytosine is unlikely to persist within meteorite parent bodies due to aqueous deamination. Thymine has a thermodynamically favourable reaction pathway from uracil, formaldehyde and formic acid, but likely did not persist within pla...

  15. Small Planetesimals in a Massive Disk Formed Mars

    CERN Document Server

    Kobayashi, Hiroshi

    2013-01-01

    Mars is likely to be a planetary embryo formed through collisions with planetesimals, which can explain its small mass and rapid formation timescale obtained from 182Hf-182$W chronometry. In the classical theory of planet formation, the final embryo mass is determined only by the solid surface density. However, embryos can stir surrounding planetesimals, leading to fragmentation through erosive (cratering) collisions. We find that radial drift of small fragments can drastically reduce the solid surface density. On the other hand, embryo growth is accelerated by fragment accretion. Since collisional fragmentation efficiency depends on the initial size of planetesimals, the final embryo mass and its growth time are determined by the initial planetesimal size and disk surface density. We have investigated the effect of these two parameters on the mass of Mars and the predicted radiogenic excess of 182W in the martian mantle. Two scenarios can explain the rapid formation of small Mars: (i) it formed by accretion ...

  16. A panoptic model for planetesimal formation and pebble delivery

    CERN Document Server

    Krijt, Sebastiaan; Dominik, Carsten; Tielens, Alexander G G M

    2016-01-01

    The journey from dust particle to planetesimal involves physical processes acting on scales ranging from micrometers (the sticking and restructuring of aggregates) to hundreds of astronomical units (the size of the turbulent protoplanetary nebula). Considering these processes simultaneously is essential when studying planetesimal formation. We develop a novel, global, semi-analytical model for the evolution of the mass-dominating dust particles in a turbulent protoplanetary disk that takes into account the evolution of the dust surface density while preserving the essential characteristics of the porous coagulation process. This panoptic model is used to study the growth from submicron to planetesimal sizes in disks around Sun-like stars. For highly porous ices, unaffected by collisional fragmentation and erosion, rapid growth to planetesimal sizes is possible in a zone stretching out to ${\\sim}10\\mathrm{~AU}$ for massive disks. When porous coagulation is limited by erosive collisions, the formation of planet...

  17. Accretion and destruction of planetesimals in turbulent disks

    CERN Document Server

    Ida, Shigeru; Morbidelli, Alessandro

    2008-01-01

    We study the conditions for collisions between planetesimals to be accretional or disruptive in turbulent disks, through analytical arguments based on fluid dynamical simulations and orbital integrations. In turbulent disks, the velocity dispersion of planetesimals is pumped up by random gravitational perturbations from density fluctuations of the disk gas. When the velocity dispersion is larger than the planetesimals' surface escape velocity, collisions between planetesimals do not result in accretion, and may even lead to their destruction. In disks with a surface density equal to that of the ``minimum mass solar nebula'' and with nominal MRI turbulence, we find that accretion proceeds only for planetesimals with sizes above $\\sim 300$ km at 1AU and $\\sim 1000$ km at 5AU. We find that accretion is facilitated in disks with smaller masses. However, at 5AU and for nominal turbulence strength, km-sized planetesimals are in a highly erosive regime even for a disk mass as small as a fraction of the mass of Jupit...

  18. Efficiency in Collisionless Growth of Planetesimals

    CERN Document Server

    Shannon, Andrew; Lithwick, Yoram

    2013-01-01

    We study the efficiency of growing large bodies, starting from a sea of equal-sized planetesimal seeds. This is likely one of the earlier steps of planet formation and is related to the origin of the asteroid belt, the Kuiper belt and extra-solar debris disks. Here we study the case that the seeds do not collide frequently enough for dynamical cooling to be important (the collisionless limit), using a newly constructed conglomeration code, and by carefully comparing numerical results with analytical scalings. We find that large bodies grow primarily by accreting small seeds (and not by accreting each other). As the velocity dispersion of the small bodies (u) is increasingly excited by the growing big bodies, growth passes from the well-known run-away stage (when u is higher than the big bodies' hill velocity) to the newly discovered trans-hill stage (when u and big bodies both grow, but u remains at the big bodies' hill velocity). We find, concurring with analytical understandings developed in Lithwick (2013)...

  19. Formation of planetesimals in the Solar Nebula

    Science.gov (United States)

    Hueso, R.; Guillot, T.

    2001-11-01

    We study the evolution of protoplanetary disks with gas and embedded particles using a classical alpha-disk model. Solid matter entrained in the gas is incorporated following the formalism of Stepinski and Valageas (A&A, 1996, 1997). Dust grains coagulate into larger particles until they eventually decouple from the gas. The coagulation process is modulated by the evaporation and condensation of dust in the disk. We simultaneously consider grains of ices and rock, which allows us to study the amount of different solid material available to form the different planets. In particular, we present consequences for the development of planetesimals in the Uranus and Neptune region. This is interesting in the light of interior models of these planets, which naturally tend to predict a low rock to ice ratio. We will also discuss the consequences of these results on the standard core-accretion formation scenario. Acknowledgements: This work has been supported by Programme National du Planetologie. R. Hueso acknowledges a post-doctoral fellowship from Gobierno Vasco.

  20. Two Beyond-Primitive Extrasolar Planetesimals

    CERN Document Server

    Xu, S; Klein, B; Koester, D; Zuckerman, B

    2013-01-01

    Using the Cosmic Origins Spectrograph onboard the Hubble Space Telescope, we have obtained high-resolution ultraviolet observations of GD 362 and PG 1225-079, two helium-dominated, externally-polluted white dwarfs. We determined or placed useful upper limits on the abundances of two key volatile elements, carbon and sulfur, in both stars; we also constrained the zinc abundance in PG 1225-079. In combination with previous optical data, we find strong evidence that each of these two white dwarfs has accreted a parent body that has evolved beyond primitive nebular condensation. The planetesimal accreted onto GD 362 had a bulk composition roughly similar to that of a mesosiderite meteorite based on a reduced chi-squared comparison with solar system objects; however, additional material is required to fully reproduce the observed mid-infrared spectrum for GD 362. No single meteorite can reproduce the unique abundance pattern observed in PG 1225-079; the best fit model requires a blend of ureilite and mesosiderite ...

  1. Atmospheric mass deposition by captured planetesimals

    Science.gov (United States)

    Iaroslavitz, Eyal; Podolak, Morris

    2007-04-01

    We examine the deposition of heavy elements in the envelope of a protoplanet growing according to the core accretion scenario of Pollack et al. [Pollack, J.B., Hubickyj, O., Bodenheimer, P., Lissauer, J.J., Podolak, M., Greenzweig, Y., 1996. Icarus 124, 62-85]. We use their atmospheric models and the deposition rates that they computed, and we calculate the amount of heavy elements that can be dissolved in the envelope. For planetesimals composed of a mixture of water, CHON, and rock, we find that almost all of the water is dissolved in the atmosphere. A substantial amount of CHON is also dissolved but it remains sequestered at high temperatures near the core. Some fraction of the rock is also dissolved in the very high temperature region near the core envelope boundary. If this dissolved material can be mixed upward later in the planet's evolution, the resulting structure would be much closer to that determined by matching the moments of Jupiter's gravitational field.

  2. Collisions of solid ice in planetesimal formation

    Science.gov (United States)

    Deckers, J.; Teiser, J.

    2016-03-01

    We present collision experiments of centimetre projectiles on to decimetre targets, both made up of solid ice, at velocities of 15-45 m s-1 at an average temperature of {T_{avg}}=255.8 ± 0.7 K. In these collisions, the centimetre body gets disrupted and part of it sticks to the target. This behaviour can be observed up to an upper threshold, that depends on the projectile size, beyond which there is no mass transfer. In collisions of small particles, as produced by the disruption of the centimetre projectiles, we also find mass transfer to the target. In this way, the larger body can gain mass, although the efficiency of the initial mass transfer is rather low. These collision results can be applied to planetesimal formation near the snowline, where evaporation and condensation is expected to produce solid ice. In free fall collisions at velocities up to about 7 m s-1, we investigated the threshold to fragmentation and coefficient of restitution of centimetre ice spheres.

  3. Collisions of solid ice in planetesimal formation

    CERN Document Server

    Deckers, J

    2016-01-01

    We present collision experiments of centimetre projectiles on to decimetre targets, both made up of solid ice, at velocities of $15\\,\\mathrm{m\\,s^{-1}}$ to $45\\,\\mathrm{m\\,s^{-1}}$ at an average temperature of $\\mathrm{T_{avg}}=255.8\\pm0.7\\,\\mathrm{K}$. In these collisions the centimetre body gets disrupted and part of it sticks to the target. This behaviour can be observed up to an upper threshold, that depends on the projectile size, beyond which there is no mass transfer. In collisions of small particles, as produced by the disruption of the centimetre projectiles, we also find mass transfer to the target. In this way the larger body can gain mass, although the efficiency of the initial mass transfer is rather low. These collision results can be applied to planetesimal formation near the snowline, where evaporation and condensation is expected to produce solid ice. In free fall collisions at velocities up to about $7\\,\\mathrm{m\\,s^{-1}}$, we investigated the threshold to fragmentation and coefficient of re...

  4. Chondrites as Samples of Differentiated Planetesimals

    Science.gov (United States)

    Elkins-Tanton, Linda; Weiss, B. P.; Zuber, M. T.

    2010-10-01

    Chondritic meteorites are unmelted, variably metamorphosed samples of the earliest solids of the solar system. The variety of metamorphic textures in ordinary chondrites motivated the "onion shell” model in which chondrites originated at varying depths within a parent body heated primarily by the short-lived radioisotope 26Al, with the highest metamorphic grade originating nearest the center (Jeffrey Taylor et al. 1987). Allende and a few other chondrites possess a unidirectional magnetization (Butler 1972, Weiss et al. 2010) that can be best explained by a core dynamo on their parent body (Funaki and Wasilewski 1999, Weiss et al. 2010), indicating internal melting and differentiation. Here we show that a parent body that accreted to > 200 km in radius by 1.7 Ma after the formation of calcium-aluminium inclusions (CAIs) could retain a solid undifferentiated crust overlying a differentiated interior, and would be consistent with formational and evolutionary constraints on the CV parent body. This body could have produced a magnetic field lasting more than 10 Ma. This hypothesis modifies the image of some chondrites as the least processed of early solar system materials, and presents them instead as the unprocessed crusts of internally melted early planetesimals. Further, the shapes and masses of the two largest asteroids, 1 Ceres and 2 Pallas, are consistent with differentiated interiors, conceivably with small iron cores with hydrated silicate or ice-silicate mantles. This research is funded by an NSF Astronomy CAREER award and a NASA/Dawn co-investigator grant.

  5. Supplementary Information for ``Rapid planetesimal formation in turbulent circumstellar discs''

    CERN Document Server

    Johansen, Anders; Mac Low, Mordecai-Mark; Klahr, Hubert; Henning, Thomas; Youdin, Andrew

    2007-01-01

    This document contains refereed supplementary information for the paper ``Rapid planetesimal formation in turbulent circumstellar discs''. It contains 15 sections (\\S1.1 -- \\S1.15) that address a number of subjects related to the main paper. We describe in detail the Poisson solver used to find the self-potential of the solid particles, including a linear and a non-linear test problem (\\S1.3). Dissipative collisions remove energy from the motion of the particles by collisional cooling (\\S1.4), an effect that allows gravitational collapse to occur in somewhat less massive discs (\\S1.7). A resolution study of the gravitational collapse of the boulders is presented in \\S1.6. We find that gravitational collapse can occur in progressively less massive discs as the grid resolution is increased, likely due to the decreased smoothing of the particle-mesh self-gravity solver with increasing resolution. In \\S1.10 we show that it is in good agreement with the Goldreich & Ward (1973) stability analysis to form severa...

  6. Hybrid methods in planetesimal dynamics: Formation of protoplanetary systems and the mill condition

    CERN Document Server

    Amaro-Seoane, Pau; Spurzem, Rainer

    2013-01-01

    The formation and evolution of protoplanetary discs remains a challenge from both a theoretical and numerical standpoint. In this work we first perform a series of tests of our new hybrid algorithm presented in Glaschke, Amaro-Seoane and Spurzem 2011 (henceforth Paper I) that combines the advantages of high accuracy of direct-summation N-body methods with a statistical description for the planetesimal disc based on Fokker-Planck techniques. We then address the formation of planets, with a focus on the formation of protoplanets out of planetesimals. We find that the evolution of the system is driven by encounters as well as direct collisions and requires a careful modelling of the evolution of the velocity dispersion and the size distribution over a large range of sizes. The simulations show no termination of the protoplanetary accretion due to gap formation, since the distribution of the planetesimals is only subjected to small fluctuations. We also show that these features are weakly correlated with the posi...

  7. A Review Paper: Contributions from the Gravity and the Kelvin Modes for the Vertical Motion Response.

    Directory of Open Access Journals (Sweden)

    Julio Buchmann

    2009-10-01

    Full Text Available In earlier papers of a series of real data integrations of the National Center for Atmospheric Research (NCAR Community Climate Model (CCM with tropical heat anomalies display regions of pronounced subsidence and drying located several thousand kilometers westward poleward of the heating for cases of tropical Atlantic heating and tropical east Pacific heating. This highly predictable sinking response is established within the first five days of these integrations. The normal-modes of a set of nonlinear primitive equations for an atmosphere: Adiabatic, hydrostatic, incompressible, dry, without friction and viscosity are linearized about a basic state at rest and used to partition model response into gravity-inertia and Rossby modes. The emphasis of this review is given upon the contributions of the gravity and Kelvin modes for the vertical motion response.

  8. On the filtering and processing of dust by planetesimals 1. Derivation of collision probabilities for non-drifting planetesimals

    CERN Document Server

    Guillot, Tristan; Ormel, Chris W

    2014-01-01

    Context. Circumstellar disks are known to contain a significant mass in dust ranging from micron to centimeter size. Meteorites are evidence that individual grains of those sizes were collected and assembled into planetesimals in the young Solar System. Aims. We assess the efficiency of dust collection of a swarm of planetesimals with radii ranging from 1 to 10^3 km and beyond. Methods. We derive analytical expressions of the probability for drifting dust to collide with planetesimals. Results. For standard turbulence conditions (i.e. a turbulence parameter {\\alpha} = 10^-2), filtering is found to be inefficient, meaning that when crossing a minimum-mass solar nebula belt of planetesimals extending between 0.1 and 35 AU most dust particles are eventually accreted by the central star. However, if the disk is weakly turbulent ({\\alpha} = 10^-4) filtering becomes efficient in two regimes: (i) For planetesimals smaller than about 10km in size and dust of all sizes and (ii) for planetary embryos larger than about ...

  9. Rocky Planetesimal Formation via Fluffy Aggregates of Nanograins

    CERN Document Server

    Arakawa, Sota

    2016-01-01

    Several pieces of evidence suggest that silicate grains in primitive meteorites are not interstellar grains but condensates formed in the early solar system. Moreover, the size distribution of matrix grains in chondrites implies that these condensates might be formed as nanometer-sized grains. Therefore, we propose a novel scenario for rocky planetesimal formation in which nanometer-sized silicate grains are produced by evaporation and recondensation events in early solar nebula, and rocky planetesimals are formed via aggregation of these nanograins. We reveal that silicate nanograins can grow into rocky planetesimals via direct aggregation without catastrophic fragmentation and serious radial drift, and our results provide a suitable condition for protoplanet formation in our solar system.

  10. From Planetesimals to Planets in Turbulent Protoplanetary Disks I. Onset of Runaway Growth

    CERN Document Server

    Kobayashi, Hiroshi; Okuzumi, Satoshi

    2015-01-01

    When planetesimals grow via collisions in a turbulent disk, stirring through density fluctuation caused by turbulence effectively increases the relative velocities between planetesimals, which suppresses the onset of runaway growth. We investigate the onset of runaway growth in a turbulent disk through simulations that calculate the mass and velocity evolution of planetesimals. When planetesimals are small, the average relative velocity between planetesimals, $v_{\\rm r}$, is much greater than their surface escape velocity, $v_{\\rm esc}$, so that runaway growth does not occur. As planetesimals become large via collisional growth, $v_{\\rm r}$ approaches $v_{\\rm esc}$. When $v_{\\rm r} \\approx 1.5 v_{\\rm esc}$, runaway growth of the planetesimals occurs. During the oligarchic growth subsequent to runaway growth, a small number of planetary embryos produced via runaway growth become massive through collisions with planetesimals with radii of that at the onset of runaway growth, $r_{\\rm p,run}$. We analytically der...

  11. Comets as collisional fragments of a primordial planetesimal disk

    CERN Document Server

    Morbidelli, Alessandro

    2015-01-01

    The Rosetta mission and its exquisite measurements have revived the debate on whether comets are pristine planetesimals or collisionally evolved objects. We investigate the collisional evolution experienced by the precursors of current comet nuclei during the early stages of the Solar System, in the context of the so-called "Nice Model". We consider two environments for the collisional evolution: (1) the trans-planetary planetesimal disk, from the time of gas removal until the disk was dispersed by the migration of the ice giants, and (2) the dispersing disk during the time that the scattered disk was formed. Simulations have been performed, using different methods in the two cases, to find the number of destructive collisions typically experienced by a comet nucleus of 2km radius. In the widely accepted scenario, where the dispersal of the planetesimal disk occurred at the time of the Late Heavy Bombardment about 4Gy ago, comet-sized planetesimals have a very small chance to survive against destructive colli...

  12. Capture and Evolution of Planetesimals in Circumjovian Disks

    CERN Document Server

    D'Angelo, Gennaro

    2015-01-01

    We study the evolution of planetesimals in evolved gaseous disks, which orbit a solar-mass star and harbor a Jupiter-mass planet at a_p~5AU. The gas dynamics is modeled with a three-dimensional hydrodynamics code that employes nested-grids and achieves a resolution of one Jupiter's radius in the circumplanetary disk. The code models solids as individual particles. Planetesimals are subjected to gravitational forces by the star and the planet, drag force by the gas, disruption via ram pressure, and mass loss through ablation. The mass evolution of solids is calculated self-consistently with their temperature, velocity, and position. We consider icy and icy/rocky bodies of radius 0.1-100km, initially deployed on orbits around the star within a few Hill radii (Rhill) of the planet's orbit. Planetesimals are scattered inward, outward, and toward disk regions of radius r>>a_p. Scattering can relocate significant amounts of solids, provided that regions |r-a_p|~ 3Rhill are replenished with planetesimals. Scattered ...

  13. Debris disks: seeing dust, thinking of planetesimals and planets

    Institute of Scientific and Technical Information of China (English)

    Alexander V.Krivov

    2010-01-01

    Debris disks are optically thin, almost gas-free dusty disks observed around a significant fraction of main-sequence stars older than about 10Myr. Since the circumstellar dust is short-lived, the very existence of these disks is considered as evidence that dust-producing planetesimals are still present in mature systems, in which planets have formed-or failed to form-a long time ago. It is inferred that these planetesimals orbit their host stars at asteroid to Kuiper-belt distances and continually supply fresh dust through mutual collisions. This review outlines observational techniques and results on debris disks, summarizes their essential physics and theoretical models, and then places them into the general context of planetary systems, uncovering interrelations between the disks, dust parent bodies, and planets. It is shown that debris disks can serve as tracers of planetesimals and planets and shed light on the planetesimal and planet formation processes that operated in these systems in the past.

  14. India's Information Technology Sector: What Contribution to Broader Economic Development? OECD Development Centre Working Paper, No. 207 (Formerly Technical Paper No. 207)

    Science.gov (United States)

    Singh, Nirvikar

    2003-01-01

    What contribution can information technology (IT) make to India's overall economic development? This paper provides an analytical framework centred around the concepts of comparative advantage, complementarities, and innovation. There is strong evidence that India has a strong and sustainable comparative advantage in software development and…

  15. The four-populations model: a new classification scheme for pre-planetesimal collisions

    CERN Document Server

    Geretshauser, Ralf J; Speith, Roland; Kley, WIlhelm

    2011-01-01

    Within the collision growth scenario for planetesimal formation, the growth step from centimetre sized pre-planetesimals to kilometre sized planetesimals is still unclear. The formation of larger objects from the highly porous pre-planetesimals may be halted by a combination of fragmentation in disruptive collisions and mutual rebound with compaction. However, the right amount of fragmentation is necessary to explain the observed dust features in late T Tauri discs. Therefore, detailed data on the outcome of pre-planetesimal collisions is required and has to be presented in a suitable and precise format. We propose and apply a new classification scheme for pre-planetesimal collisions based on the quantitative aspects of four fragment populations: the largest and second largest fragment, a power-law population, and a sub-resolution population. For the simulations of pre-planetesimal collisions, we adopt the SPH numerical scheme with extensions for the simulation of porous solid bodies. By means of laboratory b...

  16. Radial pressure in the solar nebula as affecting the motions of planetesimals. [toroidal particle concentration in planetary evolution

    Science.gov (United States)

    Whipple, F. L.

    1973-01-01

    Growing planetesimals and a range of drag laws depending on the Reynolds number and on the ratio of particle size to mean free path are considered. Particles spiral in the direction of positive gradient, thus being concentrated toward toroidal concentrations of gas. The effect increases with decreasing rates of particle growth, i.e., with increasing time scales of planet formation by accretion. In the outer regions, where evidence suggests that comets were formed and Uranus and Neptune were so accumulated, the effect of the pressure gradient is to clear the forming comets from those regions. The large mass of Neptune may have developed because of this effect, perhaps Neptune's solar distance was reduced from Bode's law, and perhaps no comet belt exists beyond Neptune. In the asteroid belt, on a slow time scale, the effect may have spiraled planetesimals toward Mars and Jupiter, thus contributing to the lack of planet formation in this region.

  17. Effects of Exoplanet Planetesimal Carbon Chemistry on Habitability

    Science.gov (United States)

    Johnson, T. V.; Mousis, O.; Lunine, J. I.; Madhusudhan, N.

    2013-12-01

    We explore the effects of reported differences in C/O values for exoplanet host stars on the composition of planetesimals formed beyond the snow line in these systems. Since the value of C/O in a planet forming nebula has a strong effect on amount of oxygen available for water ice in an oxidizing nebula, exoplanet systems for host stars with C/O greater than the solar value may have planetesimals with very little or no water ice. We have estimated the composition of volatile and refractory material in extrasolar planetesimals using a set of stars with a wide range of measured C/O abundances (Johnson et al. ApJ. 757(2), 192, 2012). The volatile ice content of planetesimals in these systems varies significantly with C/O, controlled primarily by the availability of O for H2O ice condensation. Systems with C/O less than the solar value (C/O = 0.55) should have very water ice rich planetesimals, while water ice mass fraction decreases rapidly with increasing C/O until only ices of CO and CO2 are left in significant proportions. If a significant fraction of C is in the form of refractory CHON particles, C and O are removed from the gas phase and the condensates for super-solar C/O values will be water-poor mixtures of silicates and metal, carbon, and carbon-bearing volatile ices, depending on temperature. For very carbon-rich systems, oxidizing conditions cannot be sustained beyond about C/O=1, due to the oxygen sequestered in solid silicates, oxides and CHON, for refractory C fractions within the Pollack et al. range of 0.4 - 0.7 (ApJ. 421, 615, 1994). These results have implications for assessing the habitability of exoplanets since they constrain the amount of water available beyond the snow line for dynamical delivery to inner planets, depending on the host star's C/O in the circumstellar nebula. Thus one the key chemical ingredients for habitability may be in short supply in carbon-rich, oxygen-poor systems even if planets exist in the ';habitable zone'. TVJ

  18. Does Furbearer Trapping Contribute to the Purpose or Mission? : Discussion Paper and Case Study

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — This discussion paper and case study discusses allowing economic uses of natural resources on National Wildlife Refuges in Compliance with 50 CFR 29.1

  19. Migration rates of planets due to scattering of planetesimals

    CERN Document Server

    Ormel, Chris; Tanaka, Hidekazu

    2012-01-01

    Planets migrate due to the recoil they experience from scattering solid (planetesimal) bodies. To first order, the torques exerted by the interior and exterior disks cancel, analogous to the cancellation of the torques from the gravitational interaction with the gas (type I migration). Assuming the dispersion-dominated regime and power-laws characterized by indices {\\alpha} and {\\beta} for the surface density and eccentricity profiles, we calculate the net torque on the planet. We consider both distant encounters and close (orbit-crossing) encounters. We find that the close and distant encounter torques have opposite signs with respect to their {\\alpha} and {\\beta} dependences; and that the torque is especially sensitive to the eccentricity gradient ({\\beta}). Compared to type-I migration due to excitation of density waves, the planetesimal-driven migration rate is generally lower due to the lower surface density of solids in gas-rich disk, although this may be partially or fully offset when their eccentricit...

  20. Contributed papers presented at the 24. EPS conference on controlled fusion and plasma physics

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-06-01

    In the report thirteen papers are compiled which were presented by members of the Centre de Recherches en Physique des Plasma, Lausanne, at the 24th EPS conference on controlled fusion and plasma physics. They mainly deal with problems of the confinement and are based on studies performed in the TCV tokamak. figs., tabs., refs.

  1. Initial sizes of planetesimals and accretion of the asteroids

    Science.gov (United States)

    Weidenschilling, S. J.

    2011-08-01

    The present size frequency distribution (SFD) of bodies in the asteroid belt appears to have preserved some record of the primordial population, with an excess of bodies of diameter D ˜ 100 km relative to a simple power law. The survival of Vesta's basaltic crust also implies that the early SFD had a shallow slope in the range ˜10-100 km. (Morbidelli, A., Bottke, W.F., Nesvorny, D., Levison, H.F. [2009]. Icarus 204, 558-573) were unable to produce these features by accretion from an initial population of km-sized planetesimals. They concluded that bodies with sizes in the range ˜100-1000 km and a SFD similar to the current population were produced directly from solid particles of sub-meter scale, without experiencing accretion through intermediate sizes. We present results of new accretion simulations in the primordial asteroid region. The requisite SFD can be produced from an initial population of planetesimals of sizes ≲0.1 km, smaller than the usual assumption of km-sized bodies. The bump at D ˜ 100 km is produced by a transition from dispersion-dominated runaway growth to a regime dominated by Keplerian shear, before the formation of large protoplanetary embryos. Thus, accretion of the asteroids from an initial population of small (sub-km) planetesimals cannot be ruled out.

  2. Orbital characteristics of planetesimals captured by circumplanetary gas disks

    CERN Document Server

    Suetsugu, Ryo; Fujita, Tetsuya

    2016-01-01

    Sufficiently massive growing giant planets have circumplanetary disks, and the capture of solid bodies by the disks would likely influence the growth of the planets and formation of satellite systems around them. In addition to dust particles that are supplied to the disk with inflowing gas, recent studies suggest the importance of capture of planetesimals whose motion is decoupled from the gas, but orbital evolution of captured bodies in circumplanetary gas disks has not been studied in detail. In the present work, using three-body orbital integration and analytic calculations, we examine orbital characteristics and subsequent dynamical evolution of planetesimals captured by gas drag from circumplanetary gas disks. We find that the semi-major axes of the planet-centered orbits of planetesimals at the time of permanent capture are smaller than about one third of the planet's Hill radius in most cases. Typically, captured bodies rapidly spiral into the planet, and the rate of the orbital decay is faster for th...

  3. Resolving the Planetesimal Belt of HR 8799 with ALMA

    CERN Document Server

    Booth, Mark; Casassus, Simon; Hales, Antonio S; Dent, William R F; Faramaz, Virginie; Matrà, Luca; Barkats, Denis; Brahm, Rafael; Cuadra, Jorge

    2016-01-01

    The star HR 8799 hosts one of the largest known debris discs and at least four giant planets. Previous observations have found evidence for a warm belt within the orbits of the planets, a cold planetesimal belt beyond their orbits and a halo of small grains. With the infrared data, it is hard to distinguish the planetesimal belt emission from that of the grains in the halo. With this in mind, the system has been observed with ALMA in band 6 (1.34 mm) using a compact array format. These observations allow the inner edge of the planetesimal belt to be resolved for the first time. A radial distribution of dust grains is fitted to the data using an MCMC method. The disc is best fit by a broad ring between $145^{+12}_{-12}$ AU and $429^{+37}_{-32}$ AU at an inclination of $40^{+5}_{-6}${\\deg} and a position angle of $51^{+8}_{-8}${\\deg}. A disc edge at ~145 AU is too far out to be explained simply by interactions with planet b, requiring either a more complicated dynamical history or an extra planet beyond the orb...

  4. Migration of giant planets in a time-dependent planetesimal accretion disc

    CERN Document Server

    Popolo, A D

    2002-01-01

    In this paper, we further develop the model for the migration of planets introduced in Del Popolo et al. (2001). We first model the protoplanetary nebula as a time-dependent accretion disc and find self-similar solutions to the equations of the accretion disc that give to us explicit formulas for the spatial structure and the temporal evolution of the nebula. These equations are then used to obtain the migration rate of the planet in the planetesimal disc and to study how the migration rate depends on the disc mass, on its time evolution and on some values of the dimensionless viscosity parameter alpha. We find that planets that are embedded in planetesimal discs, having total mass of 10^{-4}-0.1 M_{\\odot}, can migrate inward a large distance for low values of alpha (e.g., alpha \\simeq 10^{-3}-10^{-2}) and/or large disc mass and can survive only if the inner disc is truncated or because of tidal interaction with the star. Orbits with larger $a$ are obtained for smaller value of the disc mass and/or for larger...

  5. Migration of icy planetesimals to forming terrestrial planets

    Science.gov (United States)

    Ipatov, Sergei I.; Marov, Mikhail

    2016-07-01

    Our studies of migration of planetesimals from the feeding zone of Jupiter and Saturn to forming terrestrial planets were based on computer simulations of the orbital evolution of 10^4 planetesimals under the gravitational influence of planets. In series JN, all planets were considered in present orbits with present masses, and in series JS, Uranus and Neptune were excluded. Initial eccentricities and inclinations of planetesimals were 0.3 and 0.15 rad, respectively. Their initial semi-major axes were between 4.5 and 12 AU. Masses of planets moving in the orbits of the terrestrial planets were equal to present masses of the planets in series JS and JN, and were smaller by a factor of 10 in series JS_{01} and JN_{01}. The obtained results show that the ratio of the fraction of the planetesimals collided with an embryo of the Earth's embryo was about 2\\cdot10^{-6} and 4\\cdot10^{-7} for the mass of the embryo equal to the Earth mass and to 10% of the Earth mass, respectively. We concluded that during the growth of the mass of the Earth's embryo up to a half of the present mass of the Earth, the amount of water delivered to the embryo could be about 30% of all water delivered to the Earth from the feeding zone of Jupiter and Saturn. The total mass of water delivered to the Earth from the feeding zones of the giant planets and beyond these zones could be comparable with the mass of the Earth's oceans. A half of this water could come from the feeding zone of Jupiter and Saturn, and another half from more distant regions. Most of the water that was delivered from the distant regions to the Earth's embryo came when its mass was not small (e.g., was mainly greater than a half of the Earth mass). In series JS, the ratio of the mass of water delivered to a planet to the mass of the planet for the Earth was smaller by a factor of 2, 1.25, and 1.3 than for Mars, Venus and Mercury, respectively. For series JN, the above values of the factor were equal to 3.4, 0.7 i 0.8. For

  6. Poverty Reduction Strategy Papers and their contribution to health: An Analysis of Three Countries.

    Science.gov (United States)

    Bartlett, Sam

    2011-06-01

    Poverty Reduction Strategy Papers (PRSPs) represent the World Bank and the International Monetary Fund's (IMF) most recent initiative for reducing the plight of the poor. This paper examines whether the PRSPs for Liberia, Afghanistan and Haiti follow World Bank guidance on health. The health data, analysis and strategy content of the three PRSPs are assessed with respect to the 'Health, Nutrition and Population' chapter of the World Bank's PRSP Sourcebook. This guidance states that PRSPs should include: health data on the poor and a clear analysis showing the determinants of ill health and pro-poor health strategies. Unfortunately, none of the PRSPs analysed comply with the guidance and, consequently, do not adequately portray the health situation within their countries. Thus health is not given a high priority in the PRSP process and is seemingly low on the agenda of both poor country governments and the International Financial Institutions (IFIs). If the situation for the world's poorest people is to improve, health and the right to health need to be promoted within PRSPs.

  7. Habilitation papers, contribution to b quark physics; Memoire d'habilitation a diriger des recherches

    Energy Technology Data Exchange (ETDEWEB)

    Vasseur, G. [CEA Centre d' Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. d' Astrophysique, de la Physique des Particules, de la Physique Nucleaire et de l' Instrumentation Associee; Universite de Paris Sud, 91 - Orsay (France)

    1997-05-01

    The author reviews its contribution to particle physics through his work in different collaborations such as helios-2, OPAL and BABAR in order to get the authorization to monitor students preparing a thesis. The physics of b quark plays an important role in particle physics, no less than 5 out of 9 elements of the CKM matrix concerning quark mixing are bound to the b quark. The main part of author's scientific experience concerns b physics and its allied fields: particle detection and identification for instance. The diverse topics that are presented, are: backward-forward asymmetry of b quark, semi-leptonic branching ratio of B{sup 0}, B{sup +} mesons, CP invariance breaking in B {yields} {pi}{pi}, background noise in 4 fermions processes in the search for Higgs boson, inclusive production of protons, the OPAL detector and its trigger system, the reconstruction of photons and neutral pions in the framework of BABAR experiment, and the implications of a massive photon. (A.C.)

  8. Planetesimal Growth through the Accretion of Small Solids: Hydrodynamics Simulations with Gas-Particle Coupling

    Science.gov (United States)

    Hughes, Anna; Boley, Aaron C.

    2016-10-01

    The growth and migration of planetesimals in young protoplanetary disks are fundamental to the planet formation process. A number of mechanisms seemingly inhibit small grains from growing to sizes much larger than a centimeter, limiting planetesimal growth. In spite of this, the meteoritic record, abundance of exoplanets, and the lifetimes of disks considered altogether indicate that growth must be rapid and common. If a small number of 100-km sized planetesimals do form by some method such as the streaming instability, then gas drag effects could enable those objects to accrete small solids efficiently. In particular, accretion rates for such planetesimals could be higher or lower than rates based on the geometric cross-section and gravitational focusing alone. The local gas conditions and properties of accreting bodies select a locally optimal accretion size for the pebbles. As planetesimals accrete pebbles, they feel an additional angular momentum exchange - causing the planetesimal to slowly drift inward, which becomes significant at short orbital periods. We present self-consistent hydrodynamic simulations with direct particle integration and gas-drag coupling to evaluate the rate of planetesimal growth due to pebble accretion. We explore a range of particle sizes, planetesimal properties, and disk conditions using wind tunnel simulations. These results are followed by numerical analysis of planetesimal drift rates at a variety of stellar distances.

  9. PLANET FORMATION IN STELLAR BINARIES. I. PLANETESIMAL DYNAMICS IN MASSIVE PROTOPLANETARY DISKS

    Energy Technology Data Exchange (ETDEWEB)

    Rafikov, Roman R.; Silsbee, Kedron, E-mail: rrr@astro.princeton.edu [Department of Astrophysical Sciences, Princeton University, Ivy Lane, Princeton, NJ 08540 (United States)

    2015-01-10

    About 20% of exoplanets discovered by radial velocity surveys reside in stellar binaries. To clarify their origin one has to understand the dynamics of planetesimals in protoplanetary disks within binaries. The standard description, accounting for only gas drag and gravity of the companion star, has been challenged recently, as the gravity of the protoplanetary disk was shown to play a crucial role in planetesimal dynamics. An added complication is the tendency of protoplanetary disks in binaries to become eccentric, giving rise to additional excitation of planetesimal eccentricity. Here, for the first time, we analytically explore the secular dynamics of planetesimals in binaries such as α Cen and γ Cep under the combined action of (1) gravity of the eccentric protoplanetary disk, (2) perturbations due to the (coplanar) eccentric companion, and (3) gas drag. We derive explicit solutions for the behavior of planetesimal eccentricity e {sub p} in non-precessing disks (and in precessing disks in certain limits). We obtain the analytical form of the distribution of the relative velocities of planetesimals, which is a key input for understanding their collisional evolution. Disk gravity strongly influences relative velocities and tends to push the sizes of planetesimals colliding with comparable objects at the highest speed to small values, ∼1 km. We also find that planetesimals in eccentric protoplanetary disks apsidally aligned with the binary orbit collide at lower relative velocities than in misaligned disks. Our results highlight the decisive role that disk gravity plays in planetesimal dynamics in binaries.

  10. Commentary and contributions to green paper (alphabetical sort. Towards a European strategy for the security supply)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    major efforts in terms of Research and Development, investment aid and operational aid. Should co-financing of this aid include a contribution from sectors which received substantial initial development aid and which are now highly profitable? 8. Since nuclear energy is one of the factors in the debate on tackling climate change and energy self-sufficiency, how can the Community find a solution to the problem of nuclear waste, enhancing nuclear safety and expanding research into the reactors of the future, and in particular fusion technology? 9. Which policies should enable the European Union to meet its obligations under the Kyoto Protocol? What action could be taken in order fully to exploit potential energy savings which would help to reduce both our external dependence and CO{sub 2} emissions? 10. Can an ambitious programme to promote biofuels and other substitute fuels, including hydrogen, geared to 20% of total fuel consumption by 2020, continue to be implemented via national initiatives, or are co-ordinated decisions required on taxation, distribution and prospects for agricultural production? 11. Should energy saving in buildings, whether public or private, new or under renovation, be promoted through incentives such as tax breaks, or are regulatory measures required along the lines of those adopted for major industrial installations? 12. Energy saving in the transport sector depends on redressing the growing imbalance between road haulage and rail. Is this imbalance inevitable, or could corrective action be taken, however unpopular, notably to encourage lower use of cars in urban areas? How can the aims of opening up the sector to competition, investment in infrastructure to remove bottlenecks and inter-modality be reconciled? 13. How can we develop more collaborative visions and integrate the long-term dimension into deliberations and actions undertaken by public authorities and other involved parties in order to evolve a sustainable system of energy supply

  11. Differentiation of Planetesimals and the Thermal Consequences of Melt Migration

    CERN Document Server

    Moskovitz, Nicholas

    2011-01-01

    We model the heating of a primordial planetesimal by decay of the short-lived radionuclides Al-26 and Fe-60 to determine (i) the timescale on which melting will occur; (ii) the minimum size of a body that will produce silicate melt and differentiate; (iii) the migration rate of molten material within the interior; and (iv) the thermal consequences of the transport of Al-26 in partial melt. Our models incorporate results from previous studies of planetary differentiation and are constrained by petrologic (i.e. grain size distributions), isotopic (e.g. Pb-Pb and Hf-W ages) and mineralogical properties of differentiated achondrites. We show that formation of a basaltic crust via melt percolation was limited by the formation time of the body, matrix grain size and viscosity of the melt. We show that low viscosity (100 km in size. Differentiation would be mos t likely for planetesimals larger than 20 km in diameter that accreted within ~2.7 Myr of CAI formation.

  12. An alternative origin for debris rings of planetesimals

    CERN Document Server

    Nayakshin, Sergei

    2012-01-01

    Core Accretion, the most widely accepted scenario for planet formation, postulates existence of km-sized solid bodies, called planetesimals, arranged in a razor-thin disc in the earliest phases of planet formation. In the Tidal Downsizing hypothesis, an alternative scenario for formation of planets, grain growth, sedimentation and formation of planetary cores occur inside dense and massive gas clumps formed in the outer cold disc by gravitational instability. As a clump migrates inward, tidal forces of the star remove all or most of the gas from the clump, downsizing it to a planetary mass body. Here we argue that such a clump may form not only the planetary core but also numerous smaller bodies. As an example, we consider the simplest case of bodies on circular orbits around the planetary core in the centre of the gas clump. Bodies smaller than 1 km suffer a strong enough aerodynamic drag, spiral in and accrete onto the solid core rapidly; bodies in the planetesimal size range lose their centrifugal support ...

  13. The dust, planetesimals and planets of HD 38529

    CERN Document Server

    Moro-Martin, Amaya; Carpenter, John M; Hillenbrand, Lynne A; Wolf, Sebastian; Meyer, Michael R; Hollenbach, David J; Najita, Joan; Henning, Thomas

    2007-01-01

    HD 38529 is a post-main sequence G8III/IV star (3.5 Gyr old) with a planetary system consisting of at least two planets having Msin(i) of 0.8 MJup and 12.2 MJup, semimajor axes of 0.13 AU and 3.74 AU, and eccentricities of 0.25 and 0.35, respectively. Spitzer observations show that HD 38529 has an excess emission above the stellar photosphere, with a signal-to-noise ratio (S/N) at 70 micron of 4.7, a small excess at 33 micron (S/N=2.6) and no excess <30 micron. We discuss the distribution of the potential dust-producing planetesimals from the study of the dynamical perturbations of the two known planets, considering in particular the effect of secular resonances. We identify three dynamically stable niches at 0.4-0.8 AU, 20-50 AU and beyond 60 AU. We model the spectral energy distribution of HD 38529 to find out which of these niches show signs of harboring dust-producing plantesimals. The secular analysis, together with the SED modeling resuls, suggest that the planetesimals responsible for most of the du...

  14. Thermal Evolution And Core Formation In Planetesimals And Planetary Embryos

    Science.gov (United States)

    Sramek, O.; Labrosse, S.; Ricard, Y. R.; milelli, L.

    2011-12-01

    Recent dating of iron meteorites shows that they were formed almost as early as the oldest known objects of the solar system, the CAIs. Moreover, several meteorites show a magnetization that is thought to originate from the action of a dynamo at the early stages of the planetesimals evolution. Core formation requires melting of the metal which then can percolate toward the center, providing the solid matrix deforms and compacts. The energy source for melting of the metal comes from a combination of short lived radionuclides, mostly 26Al, and accretion energy for bodies larger than about 1000 km. We considered a suite of numerical calculations solving for the coupled problem of thermal evolution, melt percolation and matrix compaction, systematically exploring the different accretion histories, final body size and initial concentration in 26Al. Our model handles simultaneously metal and silicates in both solid and liquid states. Depending on the accretion rate, melting occurs from the center outward, in a shallow outer shell progressing inward, or in the two locations. Segregation of the protocore decreases the efficiency of radiogenic heating by confining the 26Al in the outer silicate shell. Various types of planetesimals partly differentiated and sometimes differentiated in multiple metal-silicate layers can be obtained. We discuss the thermal profiles of the accreted bodies in relation to possible early dynamo action as evidenced by remanent magnetization observed on some meteorite samples.

  15. Planetesimal fragmentation and giant planet formation: the role of planet migration

    CERN Document Server

    Guilera, O M; Alibert, Y; de Elía, G C; Santamaría, P J; Brunini, A

    2014-01-01

    In the standard model of core accretion, the cores of the giant planets form by the accretion of planetesimals. In this scenario, the evolution of the planetesimal population plays an important role in the formation of massive cores. Recently, we studied the role of planetesimal fragmentation in the in situ formation of a giant planet. However, the exchange of angular momentum between the planet and the gaseous disk causes the migration of the planet in the disk. In this new work, we incorporate the migration of the planet and globally study the role of planet migration in the formation of a massive core when the population of planetesimals evolves by planet accretion, migration due to the nebular drag, and fragmentation due to planetesimal collisions.

  16. Effect of oblique impact on impact strength of planetesimals

    Science.gov (United States)

    Yasui, Minami; Yoshida, Yusaku; Matsue, Kazuma; Takano, Shota; Arakawa, Masahiko; Ogawa, Kazunori; Okamoto, Chisato

    2016-10-01

    Collisional processes among planetesimals have played an important role for the formation and the evolution of the bodies in the solar system. Some researchers conducted impact experiments to examine the effects of target material, impact velocity, etc., on the impact strength. Planetesimals could collide with each other at various impact angles. Therefore, the effect of impact angle on the impact strength should be examined, but there are only a few studies about oblique impact experiments. In this study, we conducted oblique impact experiments of porous gypsum and glass spheres simulating planetesimals and examined the effect of the impact angle on the impact strength.We used a porous gypsum sphere and a glass sphere as a target. We carried out impact experiments by using two-stage H2 gas gun at Kobe University. A polycarbonate spherical projectile was accelerated at 2 to 7 km/s. The impact angle, θ, changed from 10° to 90° (90° at a head-on impact). The impact phenomena were observed by a high-speed camera to measure the fragment velocities.The impact strength Q* is defined as an energy density Q, which is the kinetic energy of impactor normalized by the target mass, when the largest fragment mass is half of the original target mass. In both cases of porous gypsum and glass targets, the Q* became larger as the θ decreased. We reanalyzed our results by using the effective energy density, Qc*, defined as Qsin2θ and we found that the results of oblique impacts matched with those of a head-on impact. Furthermore, the relationship between the Qc and the normalized largest fragment mass, ml/Mt, could be fitted by ml/Mt=A×Qc-p and the parameters, A and p, were 82.2 and 0.72 for a porous gypsum target and 1.1×106 and 2.12 for a glass target, respectively. We defined the impact strength Qc* by using the Qc, and the Qc* was about 1000 J/kg for both targets. The power p for a glass target was about 3 times larger than that for a porous gypsum target. This means

  17. Contribution of carbon fiber paper (CFP) to the capacitance of a CFP-supported manganese oxide supercapacitor

    Science.gov (United States)

    Chen, Dongchang; Song, Min-Kyu; Cheng, Shuang; Huang, Liang; Liu, Meilin

    2014-02-01

    While carbon fiber paper (CFP) has been widely used in batteries, fuel cells, and supercapacitors, its effect on device performance can be rather complicated. In this study, we examined the effect of CFP from different batches on the performance of a CFP-supported MnOx hybrid supercapacitor (CFP/MnOx). It is found that the contribution of the MnOx to the capacitance is dominating if the MnOx coating on CFP is dense and conformal, but becomes much less significant if the MnOx coating on CFP is porous or non-conformal. This is because annealing CFP/MnOx at 400 °C in air is necessary to obtain proper MnOx phases for high capacitance; the annealing process may increase the specific surface area of CFP if it is not fully covered by MnOx. Also, the etching of carbon surface weakens the attachment of MnOx to CFP and worsens the electrical connection of MnOx to CFP, further reducing the contribution of MnOx to capacitance. Finally, much to our surprise, it is found that the properties of the CFP varied from batches to batches, which critically influence the MnOx coating morphology/density. These factors in turn greatly affect the contribution of each component to the capacitance of the CFP/MnOx hybrid supercapacitors.

  18. Rocky Planetesimals as the Origin of Metals in DZ Stars

    CERN Document Server

    Farihi, J; Redfield, S; Dufour, P; Hambly, N C

    2010-01-01

    {Abridged}. An analysis of the calcium and hydrogen abundances, Galactic positions and kinematics of 146 DZ stars from the Sloan Digital Sky Survey demonstrates that interaction with the interstellar medium cannot account for their externally polluted atmospheres. The calcium-to-hydrogen ratios for the 37 DZA stars are dominated by super-solar values, as are the lower limits for the remaining 109 DZ stars. All together their metal-contaminated convective envelopes contain 10^{20+-2} g of calcium, commensurate with the masses of calcium inferred for large asteroids. It is probable that these stars are contaminated by circumstellar matter; the rocky remains of terrestrial planetary systems. In this picture, two predictions emerge: 1) at least 3.5% of all main sequence A- and F-type stars build terrestrial planets; and 2) the DZA stars are externally polluted by both metals and hydrogen, and hence constrain the frequency and mass of water-rich, extrasolar planetesimals.

  19. Evidence of Rocky Planetesimals Orbiting Two Hyades Stars

    CERN Document Server

    Farihi, J; Koester, D

    2013-01-01

    The Hyades is the nearest open cluster, relatively young and containing numerous A-type stars; its known age, distance, and metallicity make it an ideal site to study planetary systems around 2-3 Msun stars at an epoch similar to the late heavy bombardment. Hubble Space Telescope far-ultraviolet spectroscopy strongly suggests ongoing, external metal pollution in two remnant Hyads. For ongoing accretion in both stars, the polluting material has log[n(Si)/n(C)] > 0.2, is more carbon deficient than chondritic meteorites, and is thus rocky. These data are consistent with a picture where rocky planetesimals and small planets have formed in the Hyades around two main-sequence A-type stars, whose white dwarf descendants bear the scars. These detections via metal pollution are shown to be equivalent to infrared excesses of Lir/L* ~ 1e-6 in the terrestrial zone of the stars.

  20. Close-in planetesimal formation by pile-up of drifting pebbles

    CERN Document Server

    Drazkowska, Joanna; Moore, Ben

    2016-01-01

    The coherence of planet formation models suffers from the disconnection between the regime of small and large bodies. This is primarily caused by so-called growth barriers: the direct growth of larger bodies is halted at centimetre sized objects and particular conditions are required for the formation of larger, gravitationally bound planetesimals. We aim to connect models of dust evolution and planetesimal formation in order to identify regions of protoplanetary discs that are favourable for the formation of kilometre sized bodies and the first planetary embryos. We combine semi-analytical models of viscous protoplanetary disc evolution, dust growth and drift including backreaction of the dust particles on the gas, and planetesimal formation via the streaming instability into one numerical code. We investigate how planetesimal formation is affected by the mass of the protoplanetary disc, its initial dust content, and the stickiness of dust aggregates. We find that the dust growth and drift leads to a global ...

  1. Carbon Chemistry: Effects on Planetesimal Composition in Exoplanetary Systems

    Science.gov (United States)

    Johnson, Torrence; Lunine, Jonathan; Mousis, Olivier; Madhusudhan, Nikku

    2012-07-01

    Stellar abundances of exoplanet host stars exhibit significant variations from solar in solid forming elements, both refractory and volatile (e.g [1]). The C/O ratio is particularly important in determining the refractory (silicate and metal) to volatile ice ratio in material condensed beyond the snow line [2, 3]. Given the observed range in stellar C/O in exoplanet host stars, condensates might range from more water and volatile rich than solar system objects to volatile poor and silicate/metal rich [4]. In addition, for more carbon-rich stars (C/O > ˜0.8) refractory material in the inner part of the systems might be dominated by carbides rather than silicates [2, 5]. We have estimated the composition of volatile and refractory material in extrasolar planetesimals using a set of stars with a wide range of measured C/O abundances [6-9] and compare them with early solar system materials [10]. The volatile ice content of planetesimals in these systems varies significantly with C/O, controlled primarily by the availability of O for H_2O ice condensation. Systems with C/O less than the solar value (C/O = 0.55; [C/O] = 0 dex) should have very water ice rich planetesimals, while water ice mass fraction decreases rapidly with increasing C/O until only ices of CO and CO_2 are left in significant proportions. For larger C/O ratios, the system would become more reducing, with CH_4 becoming the major carbon-bearing gas and possibly including C as solid hydrocarbons in the condensates. If the refractory carbon phase is similar to CHON particles in comets, both carbon and oxygen are removed from the gas phase and the condensates will be water-poor mixtures of silicates and metal, carbon, and carbon-bearing volatile ices, depending on temperature. For the carbon-rich system HD4203 with (C/O > ˜1.5), condensates should range from ˜86 % mass fraction of silicate and metal for reducing conditions and no solid carbon phase to ˜70% mass fraction silicate and 30% mass fraction

  2. Silicon isotopes in angrites and volatile loss in planetesimals

    Science.gov (United States)

    Moynier, Frédéric; Savage, Paul S.; Badro, James; Barrat, Jean-Alix

    2014-01-01

    Inner solar system bodies, including the Earth, Moon, and asteroids, are depleted in volatile elements relative to chondrites. Hypotheses for this volatile element depletion include incomplete condensation from the solar nebula and volatile loss during energetic impacts. These processes are expected to each produce characteristic stable isotope signatures. However, processes of planetary differentiation may also modify the isotopic composition of geochemical reservoirs. Angrites are rare meteorites that crystallized only a few million years after calcium–aluminum-rich inclusions and exhibit extreme depletions in volatile elements relative to chondrites, making them ideal samples with which to study volatile element depletion in the early solar system. Here we present high-precision Si isotope data that show angrites are enriched in the heavy isotopes of Si relative to chondritic meteorites by 50–100 ppm/amu. Silicon is sufficiently volatile such that it may be isotopically fractionated during incomplete condensation or evaporative mass loss, but theoretical calculations and experimental results also predict isotope fractionation under specific conditions of metal–silicate differentiation. We show that the Si isotope composition of angrites cannot be explained by any plausible core formation scenario, but rather reflects isotope fractionation during impact-induced evaporation. Our results indicate planetesimals initially formed from volatile-rich material and were subsequently depleted in volatile elements during accretion. PMID:25404309

  3. Impact erosion model for gravity-dominated planetesimals

    Science.gov (United States)

    Genda, Hidenori; Fujita, Tomoaki; Kobayashi, Hiroshi; Tanaka, Hidekazu; Suetsugu, Ryo; Abe, Yutaka

    2017-09-01

    Disruptive collisions have been regarded as an important process for planet formation, while non-disruptive, small-scale collisions (hereafter called erosive collisions) have been underestimated or neglected by many studies. However, recent studies have suggested that erosive collisions are also important to the growth of planets, because they are much more frequent than disruptive collisions. Although the thresholds of the specific impact energy for disruptive collisions (QRD*) have been investigated well, there is no reliable model for erosive collisions. In this study, we systematically carried out impact simulations of gravity-dominated planetesimals for a wide range of specific impact energy (QR) from disruptive collisions (QR ∼ QRD*) to erosive ones (QR disruptive collisions (QR ∼ QRD*), the curvature of the target has a significant effect on Mej/Mtot. We also examined the angle-averaged value of Mej/Mtot and found that the numerically obtained relation between angle-averaged Mej/Mtot and QR/QRD* is very similar to the cases for θ = 45° impacts. We proposed a new erosion model based on our numerical simulations for future research on planet formation with collisional erosion.

  4. Constraints on Planetesimal Collision Models in Debris Disks

    CERN Document Server

    MacGregor, Meredith A; Chandler, Claire; Ricci, Luca; Maddison, Sarah T; Cranmer, Steven R; Andrews, Sean M; Hughes, A Meredith; Steele, Amy

    2016-01-01

    Observations of debris disks offer a window into the physical and dynamical properties of planetesimals in extrasolar systems through the size distribution of dust grains. In particular, the millimeter spectral index of thermal dust emission encodes information on the grain size distribution. We have made new VLA observations of a sample of seven nearby debris disks at 9 mm, with 3" resolution and $\\sim5$ $\\mu$Jy/beam rms. We combine these with archival ATCA observations of eight additional debris disks observed at 7 mm, together with up-to-date observations of all disks at (sub)millimeter wavelengths from the literature to place tight constraints on the millimeter spectral indices and thus grain size distributions. The analysis gives a weighted mean for the slope of the power law grain size distribution, $n(a)\\propto a^{-q}$, of $\\langle q \\rangle = 3.36\\pm0.02$, with a possible trend of decreasing $q$ for later spectral type stars. We compare our results to a range of theoretical models of collisional casca...

  5. Impact inducted surface heating by planetesimals on early Mars

    CERN Document Server

    Maindl, T I; Lammer, H; Güdel, M; Schäfer, C; Speith, R; Odert, P; Erkaev, N V; Kislyakova, K G; Pilat-Lohinger, E

    2014-01-01

    We investigate the influence of impacts of large planetesimals and small planetary embryos on the early Martian surface on the hydrodynamic escape of an early steam atmosphere that is exposed to the high soft X-ray and EUV flux of the young Sun. Impact statistics in terms of number, masses, velocities, and angles of asteroid impacts onto the early Mars are determined via n-body integrations. Based on these statistics, smoothed particle hydrodynamics (SPH) simulations result in estimates of energy transfer into the planetary surface material and according surface heating. For the estimation of the atmospheric escape rates we applied a soft X-ray and EUV absorption model and a 1-D upper atmosphere hydrodynamic model to a magma ocean-related catastrophically outgassed steam atmosphere with surface pressure values of 52 bar H2O and 11 bar CO2. The estimated impact rates and energy deposition onto an early Martian surface can account for substantial heating. The energy influx and conversion rate into internal ener...

  6. Silicon isotopes in angrites and volatile loss in planetesimals.

    Science.gov (United States)

    Pringle, Emily A; Moynier, Frédéric; Savage, Paul S; Badro, James; Barrat, Jean-Alix

    2014-12-02

    Inner solar system bodies, including the Earth, Moon, and asteroids, are depleted in volatile elements relative to chondrites. Hypotheses for this volatile element depletion include incomplete condensation from the solar nebula and volatile loss during energetic impacts. These processes are expected to each produce characteristic stable isotope signatures. However, processes of planetary differentiation may also modify the isotopic composition of geochemical reservoirs. Angrites are rare meteorites that crystallized only a few million years after calcium-aluminum-rich inclusions and exhibit extreme depletions in volatile elements relative to chondrites, making them ideal samples with which to study volatile element depletion in the early solar system. Here we present high-precision Si isotope data that show angrites are enriched in the heavy isotopes of Si relative to chondritic meteorites by 50-100 ppm/amu. Silicon is sufficiently volatile such that it may be isotopically fractionated during incomplete condensation or evaporative mass loss, but theoretical calculations and experimental results also predict isotope fractionation under specific conditions of metal-silicate differentiation. We show that the Si isotope composition of angrites cannot be explained by any plausible core formation scenario, but rather reflects isotope fractionation during impact-induced evaporation. Our results indicate planetesimals initially formed from volatile-rich material and were subsequently depleted in volatile elements during accretion.

  7. Invited and contributed papers presented by the theory group at the joint Varenna-Lausanne international workshop `theory of fusion plasmas`

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    In this report eight invited and contributed papers of the theory group are included which were presented at joint Varenna-Lausanne international workshop on `theory of fusion plasmas`. (author) figs., tabs., refs.

  8. Ohio Council on Family Relations. Proceedings of the Annual Convention (2nd, Columbus, OH, March 20, 1981). Contributed Papers.

    Science.gov (United States)

    Ohio Council on Family Relations, Columbus.

    This document contains the papers presented at the 1981 Ohio Council on Family Relations convention. The two papers from the first session on adolescent and student concerns discuss women students and the need for female role models and abortion attitudes among high school and college students. A paper in the second session on family and community…

  9. How to form planetesimals from mm-sized chondrules and chondrule aggregates

    CERN Document Server

    Carrera, Daniel; Davies, Melvyn B

    2015-01-01

    The size distribution of asteroids and Kuiper belt objects in the solar system is difficult to reconcile with a bottom-up formation scenario due to the observed scarcity of objects smaller than $\\sim$100 km in size. Instead, planetesimals appear to form top-down, with large 100-1000 km bodies forming from the rapid gravitational collapse of dense clumps of small solid particles. In this paper we investigate the conditions under which solid particles can form dense clumps in a protoplanetary disk. We use a hydrodynamic code to model the interaction between solid particles and the gas inside a shearing box inside the disk, considering particle sizes from sub-millimeter-sized chondrules to meter-sized rocks. We find that particles down to millimeter sizes can form dense particle clouds through the run-away convergence of radial drift known as the streaming instability. We make a map of the range of conditions (strength of turbulence, particle mass-loading, disk mass, and distance to the star) which are prone to ...

  10. Vega's hot dust from icy planetesimals scattered inward by an outward-migrating planetary system

    CERN Document Server

    Raymond, Sean N

    2014-01-01

    Vega has been shown to host multiple dust populations, including both hot exo-zodiacal dust at sub-AU radii and a cold debris disk extending beyond 100 AU. We use dynamical simulations to show how Vega's hot dust can be created by long-range gravitational scattering of planetesimals from its cold outer regions. Planetesimals are scattered progressively inward by a system of 5-7 planets from 30-60 AU to very close-in. In successful simulations the outermost planets are typically Neptune-mass. The back-reaction of planetesimal scattering causes these planets to migrate outward and continually interact with fresh planetesimals, replenishing the source of scattered bodies. The most favorable cases for producing Vega's exo-zodi have negative radial mass gradients, with sub-Saturn- to Jupiter-mass inner planets at 5-10 AU and outer planets of 2.5 to 20 Earth masses. The mechanism fails if a Jupiter-sized planet exists beyond ~15 AU because the planet preferentially ejects planetesimals before they can reach the inn...

  11. Global High-resolution $N$-body Simulation of Planet Formation I. Planetesimal Driven Migration

    CERN Document Server

    Kominami, Junko; Makino, Junichiro; Fujimoto, Masaki

    2016-01-01

    We investigated whether outward Planetesimal Driven Migration (PDM) takes place or not in simulations when the self gravity of planetesimals is included. We performed $N$-body simulations of planetesimal disks with large width (0.7 - 4AU) which ranges over the ice line. The simulations consisted of two stages. The first stage simulations were carried out to see the runaway growth phase using the planetesimals of initially the same mass. The runaway growth took place both at the inner edge of the disk and at the region just outside the ice line. This result was utilized for the initial setup of the second stage simulations in which the runaway bodies just outside the ice line were replaced by the protoplanets with about the isolation mass. In the second stage simulations, the outward migration of the protoplanet was followed by the stopping of the migration due to the increase of the random velocity of the planetesimals. Due to this increase of random velocities, one of the PDM criteria derived in Minton and L...

  12. Terrestrial Planets Formation around Circumbinary Habitable Zone: Inward Migration in the Planetesimal Swarm

    CERN Document Server

    Gong, Yan-Xiang; Xie, Ji-Wei

    2012-01-01

    According to the core accretion theory, circumbinary embryos can form only beyond a critical semimajor axis (CSMA). However, due to the relatively high density of solid materials in the inner disk, significant amount of small planetesimals must exist in the inner zone when embryos were forming outside this CSMA. So embryos migration induced by the planetesimal swarm is possible after the gas disk depletion. Through numerical simulations, we found (i) the scattering-driven inward migration of embryos is robust, planets can form in the habitable zone if we adopt a mass distribution of MMSN-like disk; (ii) the total mass of the planetesimals in the inner region and continuous embryo-embryo scattering are two key factors that cause significant embryo migrations; (iii) the scattering-driven migration of embryos is a natural water-deliver mechanism. We propose that planet detections should focus on the close binary with its habitable zone near CSMA.

  13. Identification of a primordial asteroid family constrains the original planetesimal population.

    Science.gov (United States)

    Delbo', Marco; Walsh, Kevin; Bolin, Bryce; Avdellidou, Chrysa; Morbidelli, Alessandro

    2017-09-08

    A quarter of known asteroids is associated with more than 100 distinct asteroid families, meaning that these asteroids originate as impact fragments from the family parent bodies. The determination of which asteroids of the remaining population are members of undiscovered families, or accreted as planetesimals from the protoplanetary disk, would constrain a critical phase of planetary formation by unveiling the unknown planetesimal size distribution. We discovered a 4-billion-year-old asteroid family extending across the entire inner part of the main belt whose members include most of the dark asteroids previously unlinked to families. This allows us to identify some original planetesimals, which are all larger than 35 kilometers, supporting the view of asteroids being born big. Their number matches the known distinct meteorite parent bodies. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  14. Formation of dust-rich planetesimals from sublimated pebbles inside of the snow line

    Science.gov (United States)

    Ida, S.; Guillot, T.

    2016-11-01

    Context. For up to a few millions of years, pebbles must provide a quasi-steady inflow of solids from the outer parts of protoplanetary disks to their inner regions. Aims: We wish to understand how a significant fraction of the pebbles grows into planetesimals instead of being lost to the host star. Methods: We examined analytically how the inward flow of pebbles is affected by the snow line and under which conditions dust-rich (rocky) planetesimals form. When calculating the inward drift of solids that is due to gas drag, we included the back-reaction of the gas to the motion of the solids. Results: We show that in low-viscosity protoplanetary disks (with a monotonous surface density similar to that of the minimum-mass solar nebula), the flow of pebbles does not usually reach the required surface density to form planetesimals by streaming instability. We show, however, that if the pebble-to-gas-mass flux exceeds a critical value, no steady solution can be found for the solid-to-gas ratio. This is particularly important for low-viscosity disks (αgrains ejected from sublimating pebbles can accumulate, eventually leading to the formation of dust-rich planetesimals directly by gravitational instability. Conclusions: This formation of dust-rich planetesimals may occur for extended periods of time, while the snow line sweeps from several au to inside of 1 au. The rock-to-ice ratio may thus be globally significantly higher in planetesimals and planets than in the central star.

  15. MAMA: An Algebraic Map for the Secular Dynamics of Planetesimals in Tight Binary Systems

    CERN Document Server

    Leiva, A M; Beaugé, C

    2013-01-01

    We present an algebraic map (MAMA) for the dynamical and collisional evolution of a planetesimal swarm orbiting the main star of a tight binary system (TBS). The orbital evolution of each planetesimal is dictated by the secular perturbations of the secondary star and gas drag due to interactions with a protoplanetary disk. The gas disk is assumed eccentric with a constant precession rate. Gravitational interactions between the planetesimals are ignored. All bodies are assumed coplanar. A comparison with full N-body simulations shows that the map is of the order of 100 times faster, while preserving all the main characteristics of the full system. In a second part of the work, we apply MAMA to the \\gamma-Cephei, searching for friendly scenarios that may explain the formation of the giant planet detected in this system. For low-mass protoplanetary disks, we find that a low-eccentricity static disk aligned with the binary yields impact velocities between planetesimals below the disruption threshold. All other sc...

  16. Collisional and Thermal Emission Models of Debris Disks: Towards Planetesimal Population Properties

    CERN Document Server

    Krivov, Alexander V; Löhne, Torsten; Mutschke, Harald

    2008-01-01

    Debris disks around main-sequence stars are believed to derive from planetesimal populations that have accreted at early epochs and survived possible planet formation processes. While debris disks must contain solids in a broad range of sizes - from big planetesimals down to tiny dust grains - debris disk observations are only sensitive to the dust end of the size distribution. Collisional models of debris disks are needed to "climb up" the ladder of the collisional cascade, from dust towards parent bodies, representing the main mass reservoir of the disks. We have used our collisional code to generate five disks around a sun-like star, assuming planetesimal belts at 3, 10, 30, 100, and 200 AU with 10 times the Edgeworth-Kuiper-belt mass density, and to evolve them for 10 Gyr. Along with an appropriate scaling rule, this effectively yields a three-parametric set of reference disks (initial mass, location of planetesimal belt, age). For all the disks, we have generated spectral energy distributions (SEDs), ass...

  17. Magnetite in CI carbonaceous meteorites - Origin by aqueous activity on a planetesimal surface

    Science.gov (United States)

    Kerridge, J. F.; Mackay, A. L.; Boynton, W. V.

    1979-01-01

    The composition and morphology of magnetite in CI carbonaceous meteorites appear incompatible with a nebular origin. Mineralization on the meteorite parent body is a more plausible mode of formation. The iodine-xenon age of this material therefore dates an episode of secondary mineralization on a planetesimal rather than the epoch of condensation in the primitive solar nebula.

  18. From Dust to Planetesimals: An Improved Model for Collisional Growth in Protoplanetary Disks

    Science.gov (United States)

    Garaud, Pascale; Meru, Farzana; Galvagni, Marina; Olczak, Christoph

    2013-02-01

    Planet formation occurs within the gas- and dust-rich environments of protoplanetary disks. Observations of these objects show that the growth of primordial submicron-sized particles into larger aggregates occurs at the earliest evolutionary stages of the disks. However, theoretical models of particle growth that use the Smoluchowski equation to describe collisional coagulation and fragmentation have so far failed to produce large particles while maintaining a significant population of small grains. This has generally been attributed to the existence of two barriers impeding growth due to bouncing and fragmentation of colliding particles. In this paper, we demonstrate that the importance of these barriers has been artificially inflated through the use of simplified models that do not take into account the stochastic nature of the particle motions within the gas disk. We present a new approach in which the relative velocities between two particles are described by a probability distribution function that models both deterministic motion (from the vertical settling, radial drift, and azimuthal drift) and stochastic motion (from Brownian motion and turbulence). Taking both into account can give quite different results to what has been considered recently in other studies. We demonstrate the vital effect of two "ingredients" for particle growth: the proper implementation of a velocity distribution function that overcomes the bouncing barrier and, in combination with mass transfer in high-mass-ratio collisions, boosts the growth of larger particles beyond the fragmentation barrier. A robust result of our simulations is the emergence of two particle populations (small and large), potentially explaining simultaneously a number of longstanding problems in protoplanetary disks, including planetesimal formation close to the central star, the presence of millimeter- to centimeter-sized particles far out in the disk, and the persistence of μm-sized grains for millions of

  19. Infall of planetesimals onto growing giant planets: onset of runaway gas accretion and metallicity of their gas envelopes

    CERN Document Server

    Shiraishi, Masakazu

    2008-01-01

    We have investigated the planetesimal accretion rate onto giant planets that are growing through gas accretion, using numerical simulations and analytical arguments. We derived the condition for gap opening in the planetesimal disk, which is determined by a competition between the expansion of the planet's Hill radius due to the planet growth and the damping of planetesimal eccentricity due to gas drag. We also derived the semi-analytical formula for the planetesimal accretion rate as a function of ratios of the rates of the Hill radius expansion, the damping, and planetesimal scattering by the planet. The predicted low planetesimal accretion rate due to gap opening in early gas accretion stages quantitatively shows that "phase 2," which is a long slow gas accretion phase before onset of runaway gas accretion, is not likely to occur. In late stages, rapid Hill radius expansion fills the gap, resulting in significant planetesimal accretion, which is as large as several $M_{\\oplus}$ for Jupiter and Saturn. The ...

  20. On the Formation of Planetesimals via Secular Gravitational Instabilities with Turbulent Stirring

    CERN Document Server

    Youdin, Andrew N

    2011-01-01

    We study the gravitational instability (GI) of small solids in a gas disk as a mechanism to form planetesimals. Dissipation from gas drag introduces secular GI, which proceeds even when standard GI criteria for a critical density or Toomre's $Q$ predict stability. We include the stabilizing effects of turbulent diffusion, which suppresses small scale GI. The radially wide rings that do collapse contain up to $\\sim 0.1$ Earth masses of solids. Subsequent fragmentation of the ring (not modeled here) would produce a clan of chemically homogenous planetesimals. Particle radial drift time scales (and, to a lesser extent, disk lifetimes and sizes) restrict the viability of secular GI to disks with weak turbulent diffusion, characterized by $\\alpha \\lesssim 10^{-4}$. Thus midplane dead zones are a preferred environment. Large solids with radii $\\gtrsim 10$ cm collapse most rapidly because they partially decouple from the gas disk. Smaller solids, even below $\\sim$ mm-sizes could collapse if particle-driven turbulenc...

  1. Planetesimal formation via sweep-up growth at the inner edge of dead zones

    CERN Document Server

    Drazkowska, J; Dullemond, C P

    2013-01-01

    The early stages of planet formation are still not well understood. Coagulation models have revealed numerous obstacles to the dust growth, such as the bouncing, fragmentation and radial drift barriers. We study the interplay between dust coagulation and drift in order to determine the conditions in protoplanetary disk that support the formation of planetesimals. We focus on planetesimal formation via sweep-up and investigate whether it can take place in a realistic protoplanetary disk. We have developed a new numerical model that resolves spatial distribution of dust in the radial and vertical dimension. The model uses representative particles approach to follow the dust evolution in protoplanetary disk. The coagulation and fragmentation of solids is taken into account using Monte Carlo method. A collision model adopting the mass transfer effect, that can occur for different-sized dust aggregate collisions, is implemented. We focus on a protoplanetary disk including a pressure bump caused by a steep decline ...

  2. Planetesimal formation by sweep-up: How the bouncing barrier can be beneficial to growth

    CERN Document Server

    Windmark, Fredrik; Güttler, Carsten; Blum, Jürgen; Dullemond, Cornelis P; Henning, Thomas

    2012-01-01

    The formation of planetesimals is often accredited to collisional sticking of dust grains. The exact process is unknown, as collisions between larger aggregates tend to lead to fragmentation or bouncing rather than sticking. Recent laboratory experiments have however made great progress in the understanding and mapping of the complex physics involved in dust collisions. We want to study the possibility of planetesimal formation using the results from the latest laboratory experiments, particularly by including the fragmentation with mass transfer effect, which might lead to growth even at high impact velocities. We present a new experimentally and physically motivated dust collision model capable of predicting the outcome of a collision between two particles of arbitrary masses and velocities. It is used together with a continuum dust-size evolution code that is both fast in terms of execution time and able to resolve the dust well at all sizes, allowing for all types of interactions to be studied without bia...

  3. The role of pebble fragmentation in planetesimal formation I. Experimental study

    CERN Document Server

    Syed, M Bukhari; Jansson, K Wahlberg; Johansen, A

    2016-01-01

    Previous work on protoplanetary dust growth shows halt at centimeter sizes owing to the occurrence of bouncing at velocities of $\\geq$ 0.1 $ms^{-1}$ and fragmentation at velocities $\\geq$ 1 $ms^{-1}$. To overcome these barriers, spatial concentration of cm-sized dust pebbles and subsequent gravitational collapse have been proposed. However, numerical investigations have shown that dust aggregates may undergo fragmentation during the gravitational collapse phase. This fragmentation in turn changes the size distribution of the solids and thus must be taken into account in order to understand the properties of the planetesimals that form. To explore the fate of dust pebbles undergoing fragmenting collisions, we conducted laboratory experiments on dust-aggregate collisions with a focus on establishing a collision model for this stage of planetesimal formation. In our experiments, we analysed collisions of dust aggregates with masses between 1.4 g and 180 g, mass ratios between target and projectile from 125 to 1 ...

  4. A New Mechanism for Chondrule Formation: Radiative Heating by Hot Planetesimals

    CERN Document Server

    Herbst, William

    2015-01-01

    We propose that chondrules are formed by radiative heating of pre-existing dust clumps during close fly-bys of planetesimals with incandescent lava at their surfaces. We show that the required temperatures and cooling rates are easily achieved in this scenario and discuss how it is consistent with bulk aspects of chondritic meteorites, including complementarity and the co-mingling of FeO-poor and FeO-rich chondrules.

  5. Planetesimal formation via sweep-up growth at the inner edge of dead zones

    Science.gov (United States)

    Drążkowska, J.; Windmark, F.; Dullemond, C. P.

    2013-08-01

    Context. The early stages of planet formation are still not well understood. Coagulation models have revealed numerous obstacles to the dust growth, such as the bouncing, fragmentation, and radial drift barriers. Gas drag causes rapid loss, and turbulence leads to generally destructive collisions between the dust aggregates. Aims: We study the interplay between dust coagulation and drift to determine the conditions in protoplanetary disk that support the formation of planetesimals. We focus on planetesimal formation via sweep-up and investigate whether it can take place in a realistic protoplanetary disk. Methods: We have developed a new numerical model that resolves the spatial distribution of dust in the radial and vertical dimensions. The model uses representative particles approach to follow the dust evolution in a protoplanetary disk. The coagulation and fragmentation of solids is taken into account in the Monte Carlo method. A collision model adopting the mass transfer effect, which can occur for different-sized dust aggregate collisions, is implemented. We focus on a protoplanetary disk that includes a pressure bump caused by a steep decline of turbulent viscosity around the snow line. Results: Our results show that high enough resolution of the vertical disk structure in dust coagulation codes is needed to obtain adequately short growth timescales, especially in the case of a low turbulence region. We find that a sharp radial variation in the turbulence strength at the inner edge of dead zone promotes planetesimal formation in several ways. It provides a pressure bump that efficiently prevents the dust from drifting inwards. It also causes a radial variation in the size of aggregates at which growth barriers occur, favoring the growth of large aggregates by sweeping up of small particles. In our model, by employing an ad hoc α viscosity change near the snow line, it is possible to grow planetesimals by incremental growth on timescales of approximately 105

  6. Comet 67P/Churyumov-Gerasimenko preserved the pebbles that formed planetesimals

    Science.gov (United States)

    Fulle, Marco; Della Corte, V.; Rotundi, A.; Rietmeijer, F. J. M.; Green, S. F.; Weissman, P.; Accolla, M.; Colangeli, L.; Ferrari, M.; Ivanovski, S.; Lopez-Moreno, J. J.; Epifani, E. Mazzotta; Morales, R.; Ortiz, J. L.; Palomba, E.; Palumbo, P.; Rodriguez, J.; Sordini, R.; Zakharov, V.

    2016-09-01

    Solar System formation models predict that the building-blocks of planetesimals were mm- to cm-sized pebbles, aggregates of ices and non-volatile materials, consistent with the compact particles ejected by comet 67P/Churyumov-Gerasimenko (67P hereafter) and detected by GIADA (Grain Impact Analyzer and Dust Accumulator) on-board the Rosetta spacecraft. Planetesimals were formed by the gentle gravitational accretion of pebbles, so that they have an internal macroporosity of 40%. We measure the average dust bulk density ρ _D = 795_{-65}^{+840} kg m-3 that, coupled to the 67P nucleus bulk density, provides the average dust-to-ices mass ratio δ = 8.5. We find that the measured densities of the 67P pebbles are consistent with a mixture of (15 ± 6)% of ices, (5 ± 2)% of Fe-sulfides, (28 ± 5)% of silicates, and (52 ± 12)% of hydrocarbons, in average volume abundances. This composition matches both the solar and CI-chondritic chemical abundances, thus showing that GIADA has sampled the typical non-volatile composition of the pebbles that formed all planetesimals. The GIADA data do not constrain the abundance of amorphous silicates vs. crystalline Mg,Fe-olivines and pyroxenes. We find that the pebbles have a microporosity of (52 ± 8)% (internal volume filling factor φP = 0.48 ± 0.08), implying an average porosity for the 67P nucleus of (71 ± 8)%, lower than previously estimated.

  7. Formation of dust-rich planetesimals from sublimated pebbles inside of the snow line

    CERN Document Server

    Ida, Shigeru

    2016-01-01

    Content: For up to a few millions of years, pebbles must provide a quasi-steady inflow of solids from the outer parts of protoplanetary disks to their inner regions. Aims: We want to understand how a significant fraction of the pebbles grow into planetesimals rather than being lost to the host star. Methods: We examine analytically how the inward flow of pebbles is affected by the presence of a snow line and under which conditions dust-rich (rocky) planetesimals form. When calculating the inward drift of solids due to gas drag, we include the back-reaction of the gas to the motion of the solids. Results: We show that in low-viscosity protoplanetary disks (with a monotonous surface density similar to that of the minimum-mass solar nebula), the flow of pebbles does not usually reach the required surface density to form planetesimals by streaming instability. We show however that if the pebble-to-gas mass flux exceeds a critical value, no steady solution can be found for the solid-to-gas ratio. Conclusions: This...

  8. Planetesimal Dynamics in Inclined Binary Systems: The Role of Gas-Disk Gravity

    CERN Document Server

    Zhao, Gang; Zhou, Ji-Lin; Lin, Douglas N C

    2012-01-01

    We investigate the effects of gas-disk gravity on the planetesimal dynamics in inclined binary systems, where the circumprimary disk plane is tilted by a significant angle ($i_B$) with respect to the binary disk plane. Our focus is on the Lidov-Kozai mechanism and the evolution of planetesimal eccentricity and inclination. Using both analytical and numerical methods, we find that, on one hand, the disk gravity generally narrows down the Kozai-on region, i.e., the Lidov-Kozai effect can be suppressed in certain parts of (or even the whole of) the disk, depending on various parameters. In the Kozai-off region, planetesimals would move on orbits close to the mid-plane of gas-disk, with the relative angle ($i^{'}$) following a small amplitude periodical oscillation. On the other hand, when we include the effects of disk gravity, we find that the Lidov-Kozai effect can operate even at arbitrarily low inclinations ($i_B$), although lower $i_B$ leads to a smaller Kozai-on region. Furthermore, in the Kozai-on region,...

  9. The Composition Of A Disrupted Extrasolar Planetesimal At SDSS J0845+2257 (Ton 345)

    CERN Document Server

    Wilson, David J; Koester, Detlev; Toloza, Odette; Pala, Anna F; Breedt, Elmé; Parsons, Steven G

    2015-01-01

    We present a detailed study of the metal-polluted DB white dwarf SDSS J0845+2257 (Ton 345). Using high-resolution HST/COS and VLT spectroscopy, we have detected hydrogen and eleven metals in the atmosphere of the white dwarf. The origin of these metals is almost certainly the circumstellar disc of dusty and gaseous debris from a tidally-disrupted planetesimal, accreting at a rate of 1.6E10 gs^-1. Studying the chemical abundances of the accreted material demonstrates that the planetesimal had a composition similar to the Earth, dominated by rocky silicates and metallic iron, with a low water content. The mass of metals within the convection zone of the white dwarf corresponds to an asteroid of at least ~130-170 km in diameter, although the presence of ongoing accretion from the debris disc implies that the planetesimal was probably larger than this. While a previous abundance study of the accreted material has shown an anomalously high mass fraction of carbon (15 percent) compared to the bulk Earth, our indepe...

  10. Impact vaporization of planetesimal cores in the late stages of planet formation

    Science.gov (United States)

    Kraus, Richard G.; Root, Seth; Lemke, Raymond W.; Stewart, Sarah T.; Jacobsen, Stein B.; Mattsson, Thomas R.

    2015-04-01

    Differentiated planetesimals delivered iron-rich material to the Earth and Moon in high-velocity collisions at the end stages of accretion. The physical process of accreting this late material has implications for the geochemical evolution of the Earth-Moon system and the timing of Earth’s core formation. However, the fraction of a planetesimal’s iron core that is vaporized by an impact is not well constrained as a result of iron’s poorly understood equation of state. Here we determine the entropy in the shock state of iron using a recently developed shock-and-release experimental technique implemented at the Sandia National Laboratory Z-Machine. We find that the shock pressure required to vaporize iron is 507 (+65, -85) GPa, which is lower than the previous theoretical estimate (887 GPa) and readily achieved by the high velocity impacts at the end stages of accretion. We suggest that impact vaporization of planetesimal cores dispersed iron over the surface of the growing Earth and enhanced chemical equilibration with the mantle. In addition, the comparatively low abundance of highly siderophile elements in the lunar mantle and crust can be explained by the retention of a smaller fraction of vaporized planetesimal iron on the Moon, as compared with Earth, due to the Moon’s lower escape velocity.

  11. Iron meteorites as remnants of planetesimals formed in the terrestrial planet region.

    Science.gov (United States)

    Bottke, William F; Nesvorný, David; Grimm, Robert E; Morbidelli, Alessandro; O'Brien, David P

    2006-02-16

    Iron meteorites are core fragments from differentiated and subsequently disrupted planetesimals. The parent bodies are usually assumed to have formed in the main asteroid belt, which is the source of most meteorites. Observational evidence, however, does not indicate that differentiated bodies or their fragments were ever common there. This view is also difficult to reconcile with the fact that the parent bodies of iron meteorites were as small as 20 km in diameter and that they formed 1-2 Myr earlier than the parent bodies of the ordinary chondrites. Here we show that the iron-meteorite parent bodies most probably formed in the terrestrial planet region. Fast accretion times there allowed small planetesimals to melt early in Solar System history by the decay of short-lived radionuclides (such as 26Al, 60Fe). The protoplanets emerging from this population not only induced collisional evolution among the remaining planetesimals but also scattered some of the survivors into the main belt, where they stayed for billions of years before escaping via a combination of collisions, Yarkovsky thermal forces, and resonances. We predict that some asteroids are main-belt interlopers (such as (4) Vesta). A select few may even be remnants of the long-lost precursor material that formed the Earth.

  12. Grain Retention and Formation of Planetesimals near the Snow Line in MRI-driven Turbulent Protoplanetary Disks

    CERN Document Server

    Kretke, Katherine A

    2007-01-01

    The first challenge in the formation of both terrestrial planets and the cores of gas giants is the retention of grains in protoplanetary disks. In most regions of these disks, gas attains sub-Keplerian speeds as a consequence of a negative pressure gradient. Hydrodynamic drag leads to orbital decay and depletion of the solid material in the disk, with characteristic timescales as short as only a few hundred years for meter-sized objects at 1 AU. In this paper, we suggest a particle retention mechanism which promotes the accumulation of grains and the formation of planetesimals near the water sublimation front or ``snow line.'' This model is based on the assumption that, in the regions most interesting for planet formation, the viscous evolution of the disk is due to turbulence driven by the magneto-rotational instability (MRI) in the surface layers of the disk. The depth to which MRI effectively generates turbulence is a strong function of the grain size and abundance. A sharp increase in the grain-to-gas de...

  13. Oligarchic planetesimal accretion and giant planet formation II

    CERN Document Server

    Fortier, A; Brunini, A

    2009-01-01

    The equation of state calculated by Saumon and collaborators has been adopted in most core--accretion simulations of giant--planet formation performed to date. Since some minor errors have been found in their original paper, we present revised simulations of giant--planet formation that considers a corrected equation of state. We employ the same code as Fortier and collaborators in repeating our previous simulations of the formation of Jupiter. Although the general conclusions of Fortier and collaborators remain valid, we obtain significantly lower core masses and shorter formation times in all cases considered. The minor errors in the previously published equation of state have been shown to affect directly the adiabatic gradient and the specific heat, causing an overestimation of both the core masses and formation times.

  14. Capture of Trans-Neptunian Planetesimals in the Main Asteroid Belt

    Science.gov (United States)

    Vokrouhlický, David; Bottke, William F.; Nesvorný, David

    2016-08-01

    The orbital evolution of the giant planets after nebular gas was eliminated from the Solar System but before the planets reached their final configuration was driven by interactions with a vast sea of leftover planetesimals. Several variants of planetary migration with this kind of system architecture have been proposed. Here, we focus on a highly successful case, which assumes that there were once five planets in the outer Solar System in a stable configuration: Jupiter, Saturn, Uranus, Neptune, and a Neptune-like body. Beyond these planets existed a primordial disk containing thousands of Pluto-sized bodies, ˜50 million D > 100 km bodies, and a multitude of smaller bodies. This system eventually went through a dynamical instability that scattered the planetesimals and allowed the planets to encounter one another. The extra Neptune-like body was ejected via a Jupiter encounter, but not before it helped to populate stable niches with disk planetesimals across the Solar System. Here, we investigate how interactions between the fifth giant planet, Jupiter, and disk planetesimals helped to capture disk planetesimals into both the asteroid belt and first-order mean-motion resonances with Jupiter. Using numerical simulations, we find that our model produces the right proportion of P- and D-type asteroids in the inner, central, and outer main belt, while also populating the Hilda and Thule regions in Jupiter’s 3/2 and 4/3 resonances. Moreover, the largest observed P/D types in each sub-population are an excellent fit to our captured population results (within uncertainties). The model produces a factor of ˜10 overabundance of diameter D > 10 km P/D types in the main belt, but this mismatch can likely be explained by various removal mechanisms (e.g., collision evolution over 4 Gyr, dynamical losses via Yarkovsky thermal forces over 4 Gyr, thermal destruction of the planetesimals en route to the inner solar system). Overall, our instability model provides a more

  15. Diffusion of Oxygen Isotopes in Thermally Evolving Planetesimals and Size Ranges of Presolar Silicate Grains

    Science.gov (United States)

    Wakita, Shigeru; Nozawa, Takaya; Hasegawa, Yasuhiro

    2017-02-01

    Presolar grains are small particles found in meteorites through their isotopic compositions, which are considerably different from those of materials in the solar system. If some isotopes in presolar grains diffused out beyond their grain sizes when they were embedded in parent bodies of meteorites, their isotopic compositions could be washed out, and hence the grains could no longer be identified as presolar grains. We explore this possibility for the first time by self-consistently simulating the thermal evolution of planetesimals and the diffusion length of 18O in presolar silicate grains. Our results show that presolar silicate grains smaller than ˜0.03 μm cannot keep their original isotopic compositions even if the host planetesimals experienced a maximum temperature as low as 600 °C. Since this temperature corresponds to that experienced by petrologic type 3 chondrites, isotopic diffusion can constrain the size of presolar silicate grains discovered in such chondrites to be larger than ˜0.03 μm. We also find that the diffusion length of 18O reaches ˜0.3-2 μm in planetesimals that were heated up to 700-800°C. This indicates that, if the original size of presolar grains spans a range from ˜0.001 μm to ˜0.3 μm like that in the interstellar medium, then the isotopic records of the presolar grains may be almost completely lost in such highly thermalized parent bodies. We propose that isotopic diffusion could be a key process to control the size distribution and abundance of presolar grains in some types of chondrites.

  16. Magnesium isotope evidence for single stage formation of CB chondrules by colliding planetesimals

    DEFF Research Database (Denmark)

    Olsen, M.B.; Schiller, Martin; Krot, A.N.

    2013-01-01

    to their stable Mg-isotope composition (μMg), indicating that the correlated variability was imparted by a volatility-controlled process (evaporation/condensation). The mass-independent Mg composition (μMg*) of chondrules is consistent with single stage formation from an initially homogeneous magnesium reservoir...... planetesimals. The inferred μMg* value of -3.87 ± 0.93 ppm for the CB parent body is significantly lower than the bulk solar system value of 4.5 ± 1.1 ppm inferred from CI chondrites, suggesting that CB chondrites accreted material comprising an early formed Al-free component. © 2013. The American Astronomical...

  17. MAGNESIUM ISOTOPE EVIDENCE FOR SINGLE STAGE FORMATION OF CB CHONDRULES BY COLLIDING PLANETESIMALS

    DEFF Research Database (Denmark)

    Olsen, Mia Bjørg Stolberg; Schiller, Martin; Krot, Alexander N.

    2013-01-01

    correlated to their stable Mg-isotope composition (μ25Mg), indicating that the correlated variability was imparted by a volatility-controlled process (evaporation/condensation). The mass-independent 26Mg composition (μ26Mg*) of chondrules is consistent with single stage formation from an initially...... in the impact-generated plume of colliding planetesimals. The inferred μ26Mg* value of –3.87 ± 0.93 ppm for the CB parent body is significantly lower than the bulk solar system value of 4.5 ± 1.1 ppm inferred from CI chondrites, suggesting that CB chondrites accreted material comprising an early formed 26Al...

  18. Planetesimal Formation by Gravitational Instability of a Porous-Dust Disk

    CERN Document Server

    Michikoshi, Shugo

    2016-01-01

    Recently it is proposed that porous icy dust aggregates are formed by pairwise accretion of dust aggregates beyond the snowline. We calculate the equilibrium random velocity of porous dust aggregates taking into account mutual gravitational scattering, collisions, gas drag, and turbulent stirring and scattering. We find that the disk of porous dust aggregates becomes gravitationally unstable as they evolve through gravitational compression in the minimum-mass solar nebula model for a reasonable range of turbulence strength, which leads to rapid formation of planetesimals.

  19. N-Body Simulation of Planetesimal Formation through Gravitational Instability of a Dust Layer in Laminar Gas Disk

    CERN Document Server

    Michikoshi, Shugo; Inutsuka, Shu-ichiro

    2010-01-01

    We investigate the formation process of planetesimals from the dust layer by the gravitational instability in the gas disk using local $N$-body simulations. The gas is modeled as a background laminar flow. We study the formation process of planetesimals and its dependence on the strength of the gas drag. Our simulation results show that the formation process is divided into three stages qualitatively: the formation of wake-like density structures, the creation of planetesimal seeds, and their collisional growth. The linear analysis of the dissipative gravitational instability shows that the dust layer is secularly unstable although Toomre's $Q$ value is larger than unity. However, in the initial stage, the growth time of the gravitational instability is longer than that of the dust sedimentation and the decrease in the velocity dispersion. Thus, the velocity dispersion decreases and the disk shrinks vertically. As the velocity dispersion becomes sufficiently small, the gravitational instability finally become...

  20. Ice Lines, Planetesimal Composition and Solid Surface Density in the Solar Nebula

    CERN Document Server

    Robinson, Sarah E; Bodenheimer, Peter; Laughlin, Gregory; Turner, Neal J; Beichman, C A

    2008-01-01

    To date, there is no core accretion simulation that can successfully account for the formation of Uranus or Neptune within the observed 2-3 Myr lifetimes of protoplanetary disks. Since solid accretion rate is directly proportional to the available planetesimal surface density, one way to speed up planet formation is to take a full accounting of all the planetesimal-forming solids present in the solar nebula. By combining a viscously evolving protostellar disk with a kinetic model of ice formation, we calculate the solid surface density in the solar nebula as a function of heliocentric distance and time. We find three effects that strongly favor giant planet formation: (1) a decretion flow that brings mass from the inner solar nebula to the giant planet-forming region, (2) recent lab results (Collings et al. 2004) showing that the ammonia and water ice lines should coincide, and (3) the presence of a substantial amount of methane ice in the trans-Saturnian region. Our results show higher solid surface densitie...

  1. Formation of Cosmic Crystals in Highly-Supersaturated Silicate Vapor Produced by Planetesimal Bow Shocks

    CERN Document Server

    Miura, H; Yamamoto, T; Nakamoto, T; Yamada, J; Tsukamoto, K; Nozawa, J

    2010-01-01

    Several lines of evidence suggest that fine silicate crystals observed in primitive meteorite and interplanetary dust particles (IDPs) nucleated in a supersaturated silicate vapor followed by crystalline growth. We investigated evaporation of $\\mu$m-sized silicate particles heated by a bow shock produced by a planetesimal orbiting in the gas in the early solar nebula and condensation of crystalline silicate from the vapor thus produced. Our numerical simulation of shock-wave heating showed that these {\\mu}m-sized particles evaporated almost completely when the bow shock is strong enough to cause melting of chondrule precursor dust particles. We found that the silicate vapor cools very rapidly with expansion into the ambient unshocked nebular region; the cooling rate is estimated, for instance, to be as high as 2000 K s$^{-1}$ for a vapor heated by a bow shock associated with a planetesimal of radius 1 km. The rapid cooling of the vapor leads to nonequilibrium gas-phase condensation of dust at temperatures muc...

  2. Multiwavelength Transit Observations of the Candidate Disintegrating Planetesimals Orbiting WD 1145+017

    CERN Document Server

    Croll, Bryce; Vanderburg, Andrew; Eastman, Jason; Rappaport, Saul; DeVore, John; Bieryla, Allyson; Muirhead, Philip S; Han, Eunkyu; Latham, David W; Beatty, Thomas G; Wittenmyer, Robert A; Wright, Jason T; Johnson, John Asher; McCrady, Nate

    2015-01-01

    We present multiwavelength, multi-telescope, ground-based follow-up photometry of the white dwarf WD 1145+017, that has recently been suggested to be orbited by up to six or more, short-period, low-mass, disintegrating planetesimals. We detect 9 significant dips in flux of between 10% and 30% of the stellar flux from our ground-based photometry. We observe transits deeper than 10% on average every ~3.6 hr in our photometry. This suggests that WD 1145+017 is indeed being orbited by multiple, short-period objects. Through fits to the multiple asymmetric transits that we observe, we confirm that the transit egress timescale is usually longer than the ingress timescale, and that the transit duration is longer than expected for a solid body at these short periods, all suggesting that these objects have cometary tails streaming behind them. The precise orbital periods of the planetesimals in this system are unclear from the transit-times, but at least one object, and likely more, have orbital periods of ~4.5 hours....

  3. What Children Tell Us about Their Parents: From Visible Dust to Invisible Planetesimals in Debris Disks

    Science.gov (United States)

    Mueller, Sebastian; Krivov, A. V.; Loehne, T.; Mutschke, H.

    2008-09-01

    Various small body families in the solar system, together with dust they produce through mutual collisions and cometary activity, exemplify a non-planetary component of a planetary system, usually referred to as a "debris disk". Debris disks have been found to be a common phenomenon for main-sequence stars and, similar to the solar system, are believed to comprise planetesimal populations that have accreted at early epochs and survived possible planet formation. However, in contrast to the solar system, observations of extrasolar debris disks only show their dusty portion, whereas the dust-producing planetesimals remain invisible. We show how collisional models of debris disks can be used to "climb up" the ladder of the collisional cascade, from dust towards parent bodies, representing the main mass reservoir of the disks. Applying our approach to five sun-like stars known to harbor dust, we find that the observed excess emission in far-IR to sub-mm is compatible with debris disks collisionally sustained by "large Kuiper belts" of 0.2-50 earth masses (in the bodies up to 100 km in size) with radii of 100-200 AU, larger than thought before. This research has been funded by the Deutsche Forschungsgemeinschaft (DFG), projects Kr 2164/5-1 and Mu 1164/6-1, by the Deutscher Akademischer Austauschdienst (DAAD), project D/0707543, and by the International Space Science Institute (Bern).

  4. Modelling circumbinary protoplanetary disks II. Gas disk feedback on planetesimal dynamical and collisional evolution in the circumbinary systems Kepler-16 and 34

    CERN Document Server

    Lines, S; Baruteau, C; Paardekooper, S -J; Carter, P J

    2016-01-01

    Aims. We investigate the feasibility of planetesimal growth in circumbinary protoplanetary disks around the observed systems Kepler- 16 and Kepler-34 under the gravitational influence of a precessing eccentric gas disk. Methods. We embed the results of our previous hydrodynamical simulations of protoplanetary disks around binaries into an N-body code to perform 3D, high-resolution, inter-particle gravity-enabled simulations of planetesimal growth and dynamics that include the gravitational force imparted by the gas. Results. Including the full, precessing asymmetric gas disk generates high eccentricity orbits for planetesimals orbiting at the edge of the circumbinary cavity, where the gas surface density and eccentricity have their largest values. The gas disk is able to efficiently align planetesimal pericenters in some regions leading to phased, non-interacting orbits. Outside of these areas eccentric planetesimal orbits become misaligned and overlap leading to crossing orbits and high relative velocities d...

  5. Planetesimal formation by sweep-up: how the bouncing barrier can be beneficial to growth

    Science.gov (United States)

    Windmark, F.; Birnstiel, T.; Güttler, C.; Blum, J.; Dullemond, C. P.; Henning, Th.

    2012-04-01

    Context. The formation of planetesimals is often accredited to the collisional sticking of dust grains. The exact process is unknown, as collisions between larger aggregates tend to lead to fragmentation or bouncing rather than sticking. Recent laboratory experiments have however made great progress in the understanding and mapping of the complex physics involved in dust collisions. Aims: We study the possibility of planetesimal formation using the results of the latest laboratory experiments, particularly by including the fragmentation with mass transfer effect, which might lead to growth even at high impact velocities. Methods: We present a new experimentally and physically motivated dust collision model capable of predicting the outcome of a collision between two particles of arbitrary mass and velocity. The new model includes a natural description of cratering and mass transfer, and provides a smooth transition from equal- to different-sized collisions. It is used together with a continuum dust-size evolution code, which is both fast in terms of execution time and able to resolve the dust at all sizes, allowing for all types of interactions to be studied without biases. Results: For the general dust population, we find that bouncing collisions prevent any growth above millimeter-sizes. However, if a small number of cm-sized particles are introduced, for example by either vertical mixing or radial drift, they can act as a catalyst and start to sweep up the smaller particles. At a distance of 3 AU, 100-m-sized bodies are formed on a timescale of 1 Myr. Conclusions: Direct growth of planetesimals might be a possibility thanks to a combination of the bouncing barrier and the fragmentation with mass transfer effect. The bouncing barrier is here even beneficial, as it prevents the growth of too many large particles that would otherwise only fragment among each other, and creates a reservoir of small particles that can be swept up by larger bodies. However, for this

  6. The Mass and Size Distribution of Planetesimals Formed by the Streaming Instability. I. The Role of Self-gravity

    Science.gov (United States)

    Simon, Jacob B.; Armitage, Philip J.; Li, Rixin; Youdin, Andrew N.

    2016-05-01

    We study the formation of planetesimals in protoplanetary disks from the gravitational collapse of solid over-densities generated via the streaming instability. To carry out these studies, we implement and test a particle-mesh self-gravity module for the Athena code that enables the simulation of aerodynamically coupled systems of gas and collisionless self-gravitating solid particles. Upon employment of our algorithm to planetesimal formation simulations, we find that (when a direct comparison is possible) the Athena simulations yield predicted planetesimal properties that agree well with those found in prior work using different numerical techniques. In particular, the gravitational collapse of streaming-initiated clumps leads to an initial planetesimal mass function that is well-represented by a power law, {dN}/{{dM}}p\\propto {M}p-p, with p≃ 1.6+/- 0.1, which equates to a differential size distribution of {dN}/{{dR}}p\\propto {R}p-q, with q≃ 2.8+/- 0.1. We find no significant trends with resolution from a convergence study of up to 5123 grid zones and {N}{{par}}≈ 1.5× {10}8 particles. Likewise, the power-law slope appears indifferent to changes in the relative strength of self-gravity and tidal shear, and to the time when (for reasons of numerical economy) self-gravity is turned on, though the strength of these claims is limited by small number statistics. For a typically assumed radial distribution of minimum mass solar nebula solids (assumed here to have dimensionless stopping time τ =0.3), our results support the hypothesis that bodies on the scale of large asteroids or Kuiper Belt Objects could have formed as the high-mass tail of a primordial planetesimal population.

  7. Thermal evolution and sintering of chondritic planetesimals II. Improved treatment of the compaction process

    CERN Document Server

    Gail, Hans-Peter; Trieloff, Mario

    2014-01-01

    Reconstruction of the thermal history of individual meteorites which can be assigned to the same parent body allows to derive general characteristics of the parent body, which hold important clues on the planetary formation process. This requires to construct models for the heating of such bodies by short lived radioactives, in particular by 26Al, and its cooling by heat conduction, which then are compared with the cooling histories of the meteorites. The heat conductivity of the planetesimal material depends critically on the porosity of the chondritic material and changes by sintering of the material at elevated temperatures and pressures. Compaction of a granular material is a key process for the thermal history of the parent bodies of meteorites. The modelling of the compaction process is improved by applying concepts originally developed for hot isostatic pressing in metallurgical processes. It is extended to a binary mixture of matrix and chondrules, as observed in chondrites. By comparison with publish...

  8. Synthesis of Amino Acid Precursors with Organic Solids in Planetesimals with Liquid Water

    Science.gov (United States)

    Kebukawa, Y; Misawa, S.; Matsukuma, J.; Chan, Q. H. S.; Kobayashi, J.; Tachibana, S.; Zolensky, M. E.

    2017-01-01

    Amino acids are important ingredients of life that would have been delivered to Earth by extraterrestrial sources, e.g., comets and meteorites. Amino acids are found in aqueously altered carbonaceous chondrites in good part in the form of precursors that release amino acids after acid hydrolysis. Meanwhile, most of the organic carbon (greater than 70 weight %) in carbonaceous chondrites exists in the form of solvent insoluble organic matter (IOM) with complex macromolecular structures. Complex macromolecular organic matter can be produced by either photolysis of interstellar ices or aqueous chemistry in planetesimals. We focused on the synthesis of amino acids during aqueous alteration, and demonstrated one-pot synthesis of a complex suite of amino acids simultaneously with IOM via hydrothermal experiments simulating the aqueous processing

  9. Planetesimal and Protoplanet Dynamics in a Turbulent Protoplanetary Disk: Ideal Stratified Disks

    CERN Document Server

    Yang, Chao-Chin; Menou, Kristen

    2011-01-01

    Due to the gravitational influence of density fluctuations driven by magneto-rotational instability in the gas disk, planetesimals and protoplanets undergo diffusive radial migration as well as changes in other orbital properties. The magnitude of the effect on particle orbits can have important consequences for planet formation scenarios. We use the local-shearing-box approximation to simulate an ideal, isothermal, magnetized gas disk with vertical density stratification and simultaneously evolve numerous massless particles moving under the gravitational field of the gas and the host star. We measure the evolution of the particle orbital properties, including mean radius, eccentricity, inclination, and velocity dispersion, and its dependence on the disk properties and the particle initial conditions. Although the results converge with resolution for fixed box dimensions, we find the response of the particles to the gravity of the turbulent gas correlates with the horizontal box size, up to 16 disk scale heig...

  10. Models of Angular Momentum Input to a Circumterrestrial Swarm from Encounters with Heliocentric Planetesimals

    Science.gov (United States)

    Davis, D. R.; Greenberg, R.; Hebert, F.

    1985-01-01

    Models of lunar origin in which the Moon accretes in orbit about the Earth from material approaching the Earth from heliocentric orbits must overcome a fundamental problem: the approach orbits of such material would be, in the simplest approximation, equally likely to be prograde or retrograde about the Earth, with the result that accretion of such material adds mass but not angular momentum to circumterrestrial satellites. Satellite orbits would then decay due to the resulting drag, ultimately impacting onto the Earth. One possibility for adding both material and angular momentum to Earth orbit is investigated: imbalance in the delivered angular momentum between pro and retrograde Earth passing orbits which arises from the three body dynamics of planetesimals approaching the Earth from heliocentric space. In order to study angular momentum delivery to circumterrestrial satellites, the near Earth velocities were numerically computed as a function of distance from the Earth for a large array of orbits systematically spanning heliocentric phase space.

  11. Early Thermal Evolution of Planetesimals and its Impact on Processing and Dating of Meteoritic Material

    CERN Document Server

    Gail, H -P; Breuer, D; Spohn, T

    2013-01-01

    Radioisotopic ages for meteorites and their components provide constraints on the evolution of small bodies: timescales of accretion, thermal and aqueous metamorphism, differentiation, cooling and impact metamorphism. Realising that the decay heat of short-lived nuclides (e.g. 26Al, 60Fe), was the main heat source driving differentiation and metamorphism, thermal modeling of small bodies is of utmost importance to set individual meteorite age data into the general context of the thermal evolution of their parent bodies, and to derive general conclusions about the nature of planetary building blocks in the early solar system. As a general result, modelling easily explains that iron meteorites are older than chondrites, as early formed planetesimals experienced a higher concentration of short-lived nuclides and more severe heating. However, core formation processes may also extend to 10 Ma after formation of Calcium-Aluminum-rich inclusions (CAIs). A general effect of the porous nature of the starting material ...

  12. Water transport to circumprimary habitable zones from icy planetesimal disks in binary star systems

    Science.gov (United States)

    Bancelin, D.; Pilat-Lohinger, E.; Maindl, T. I.; Bazsó, Á.

    2017-03-01

    So far, more than 130 extrasolar planets have been found in multiple stellar systems. Dynamical simulations show that the outcome of the planetary formation process can lead to different planetary architectures (i.e. location, size, mass, and water content) when the star system is single or double. In the late phase of planetary formation, when embryo-sized objects dominate the inner region of the system, asteroids are also present and can provide additional material for objects inside the habitable zone (HZ). In this study, we make a comparison of several binary star systems and aim to show how efficient they are at moving icy asteroids from beyond the snow line into orbits crossing the HZ. We also analyze the influence of secular and mean motion resonances on the water transport towards the HZ. Our study shows that small bodies also participate in bearing a non-negligible amount of water to the HZ. The proximity of a companion moving on an eccentric orbit increases the flux of asteroids to the HZ, which could result in a more efficient water transport on a short timescale, causing a heavy bombardment. In contrast to asteroids moving under the gravitational perturbations of one G-type star and a gas giant, we show that the presence of a companion star not only favors a faster depletion of our disk of planetesimals, but can also bring 4-5 times more water into the whole HZ. However, due to the secular resonance located either inside the HZ or inside the asteroid belt, impacts between icy planetesimals from the disk and big objects in the HZ can occur at high impact speed. Therefore, real collision modeling using a GPU 3D-SPH code show that in reality, the water content of the projectile is greatly reduced and therefore, also the water transported to planets or embryos initially inside the HZ.

  13. Contribution and influence of proceedings papers to citation impact in seven conference and journal-driven sub-fields of energy research 2005-11

    DEFF Research Database (Denmark)

    Ingwersen, Peter; Larsen, Birger; Garcia-Zorita, J. Carlos

    2013-01-01

    and Wave Energy, Geo-thermal, Bio-fuel and Bio-mass energy sub-fields. The analyses cover research and review articles as well as conference proceeding papers excluding meeting abstracts published 2005-09 and cited 2005-11 through Web of Science. Central findings are: The distribution across document types......This paper analyses the following seven sub-fields of Sustainable Energy Research with respect to the influence of conference paper dominance on citation patterns across citing and cited document types, overall sub-field and document type impacts and citedness: Wind Power, Renewable Energy, Solar...... and cited vs. citing documents is highly asymmetric. Predominantly proceeding papers cite research articles. With decreasing conference dominance the segment of proceeding papers citing proceeding papers decreases (from 22 % to 14 %). Simultaneously, the share of all publication types that actually...

  14. Poster papers

    Science.gov (United States)

    Schulz, Michael

    In many scientific societies, presentation by poster has become a popular alternative to oral delivery for contributed papers at major meetings. This has not been so in the AGU. My purpose in this 'editorial' is to acquaint the AGU membership with some of the advantages of the poster paper as an occasional alternative to the 10-minute talk.The main advantage for the author of a poster paper is the opportunity for interaction with an interested audience for a 3 hour period. Significant feedback from the audience is a bonus that gives the author a better understanding of his own work and how to explain it, both orally and in print. Those of us who have tried poster presentation have found it to be a very positive experience.

  15. Contribution and influence of proceedings papers to citation impact in seven conference and journal-driven sub-fields of energy research 2005-11

    DEFF Research Database (Denmark)

    Ingwersen, Peter; Larsen, Birger; Garcia-Zorita, J. Carlos;

    2013-01-01

    and Wave Energy, Geo-thermal, Bio-fuel and Bio-mass energy sub-fields. The analyses cover research and review articles as well as conference proceeding papers excluding meeting abstracts published 2005-09 and cited 2005-11 through Web of Science. Central findings are: The distribution across document types......This paper analyses the following seven sub-fields of Sustainable Energy Research with respect to the influence of conference paper dominance on citation patterns across citing and cited document types, overall sub-field and document type impacts and citedness: Wind Power, Renewable Energy, Solar...

  16. Azimuthal asymmetries in the debris disk around HD 61005. A massive collision of planetesimals?

    Science.gov (United States)

    Olofsson, J.; Samland, M.; Avenhaus, H.; Caceres, C.; Henning, Th.; Moór, A.; Milli, J.; Canovas, H.; Quanz, S. P.; Schreiber, M. R.; Augereau, J.-C.; Bayo, A.; Bazzon, A.; Beuzit, J.-L.; Boccaletti, A.; Buenzli, E.; Casassus, S.; Chauvin, G.; Dominik, C.; Desidera, S.; Feldt, M.; Gratton, R.; Janson, M.; Lagrange, A.-M.; Langlois, M.; Lannier, J.; Maire, A.-L.; Mesa, D.; Pinte, C.; Rouan, D.; Salter, G.; Thalmann, C.; Vigan, A.

    2016-06-01

    Context. Debris disks offer valuable insights into the latest stages of circumstellar disk evolution, and can possibly help us to trace the outcomes of planetary formation processes. In the age range 10 to 100 Myr, most of the gas is expected to have been removed from the system, giant planets (if any) must have already been formed, and the formation of terrestrial planets may be on-going. Pluto-sized planetesimals, and their debris released in a collisional cascade, are under their mutual gravitational influence, which may result into non-axisymmetric structures in the debris disk. Aims: High angular resolution observations are required to investigate these effects and constrain the dynamical evolution of debris disks. Furthermore, multi-wavelength observations can provide information about the dust dynamics by probing different grain sizes. Methods: Here we present new VLT/SPHERE and ALMA observations of the debris disk around the 40 Myr-old solar-type star HD 61005. We resolve the disk at unprecedented resolution both in the near-infrared (in scattered and polarized light) and at millimeter wavelengths. We perform a detailed modeling of these observations, including the spectral energy distribution. Results: Thanks to the new observations, we propose a solution for both the radial and azimuthal distribution of the dust grains in the debris disk. We find that the disk has a moderate eccentricity (e ~ 0.1) and that the dust density is two times larger at the pericenter compared to the apocenter. Conclusions: With no giant planets detected in our observations, we investigate alternative explanations besides planet-disk interactions to interpret the inferred disk morphology. We postulate that the morphology of the disk could be the consequence of a massive collision between ~1000 km-sized bodies at ~61 au. If this interpretation holds, it would put stringent constraints on the formation of massive planetesimals at large distances from the star. Based on observations

  17. Planetesimal Clearing and Size-dependent Asteroid Retention by Secular Resonance Sweeping during the Depletion of the Solar Nebula

    Science.gov (United States)

    Zheng, Xiaochen; Lin, Douglas N. C.; Kouwenhoven, M. B. N.

    2017-02-01

    The distribution of heavy elements is anomalously low in the asteroid main belt region compared with elsewhere in the solar system. Observational surveys also indicate a deficit in the number of small (≲50 km size) asteroids, which is two orders of magnitude lower than what is expected from the single power-law distribution that results from a collisional coagulation and fragmentation equilibrium. Here, we consider the possibility that a major fraction of the original asteroid population may have been cleared out by Jupiter’s secular resonance, as it swept through the main asteroid belt during the depletion of the solar nebula. This effect leads to the excitation of the asteroids’ orbital eccentricities. Concurrently, hydrodynamic drag and planet–disk tidal interaction effectively damp the eccentricities of sub-100 km-size and of super-lunar-size planetesimals, respectively. These combined effects lead to the asteroids’ orbital decay and clearing from the present-day main belt region (∼2.1–3.3 au). Eccentricity damping for the intermediate-size (50 to several hundreds of kilometers) planetesimals is less efficient than for small or large planetesimals. These objects therefore preferentially remain as main belt asteroids near their birthplaces, with modest asymptotic eccentricities. The smaller asteroids are the fragments of subsequent disruptive collisions at later times as suggested by the present-day asteroid families. This scenario provides a natural explanation for both the observed low surface density and the size distribution of asteroids in the main belt, without the need to invoke special planetesimal formation mechanisms. It also offers an explanation for the confined spatial extent of the terrestrial planet building blocks without the requirement of extensive migration of Jupiter, which is required in the grand-tack scenario.

  18. The effects of short-lived radionuclides and porosity on the early thermo-mechanical evolution of planetesimals

    CERN Document Server

    Lichtenberg, Tim; Gerya, Taras V; Meyer, Michael R

    2016-01-01

    The thermal history and internal structure of chondritic planetesimals, assembled before the giant impact phase of chaotic growth, potentially yield important implications for the final composition and evolution of terrestrial planets. These parameters critically depend on the internal balance of heating versus cooling, which is mostly determined by the presence of short-lived radionuclides (SLRs), such as aluminum-26 and iron-60, as well as the heat conductivity of the material. The heating by SLRs depends on their initial abundances, the formation time of the planetesimal and its size. It has been argued that the cooling history is determined by the porosity of the granular material, which undergoes dramatic changes via compaction processes and tends to decrease with time. In this study we assess the influence of these parameters on the thermo-mechanical evolution of young planetesimals with both 2D and 3D simulations. Using the code family I2ELVIS/I3ELVIS we have run numerous 2D and 3D numerical finite-dif...

  19. Planetesimal formation in self-gravitating discs -- dust trapping by vortices

    CERN Document Server

    Gibbons, P G; Rice, W K M

    2015-01-01

    The mechanism through which meter-sized boulders grow to km-sized planetesimals in protoplanetary discs is a subject of active research, since it is critical for planet formation. To avoid spiralling into the protostar due to aerodynamic drag, objects must rapidly grow from cm-sized pebbles, which are tightly coupled to the gas, to large boulders of 1-100m in diameter. It is already well known that over-densities in the gaseous component of the disc provide potential sites for the collection of solids, and that significant density structures in the gaseous component of the disc (e.g., spiral density waves) can trap solids efficiently enough for the solid component of the disc to undergo further gravitational collapse due to their own self-gravity. In this work, we employ the PENCIL CODE to conduct local shearing sheet simulations of massive self-gravitating protoplanetary discs, to study the effect of anticyclonic transient vortices, or eddies, on the evolution of solids in these discs. We find that these typ...

  20. Massive collision of planetesimals in the asymmetric disk around HD61005

    CERN Document Server

    Olofsson, J; Avenhaus, H; Caceres, C; Henning, Th; Moor, A; Milli, J; Canovas, H; Quanz, S; Schreiber, M R; Augereau, J -C; Bayo, A; Bazzon, A; Beuzit, J -L; Boccaletti, A; Buenzli, E; Casassus, S; Chauvin, G; Dominik, C; Desidera, S; Feldt, M; Gratton, R; Janson, M; Lagrange, A -M; Langlois, M; Lannier, J; Maire, A -L; Mesa, D; Pinte, C; Rouan, D; Salter, G; Thalmann, C; Vigan, A

    2016-01-01

    Debris disks offer valuable insights into the latest stages of circumstellar disk evolution, and can possibly trace the outcomes of planetary formation processes. In the age range 10 to 100 Myr, most of the gas is expected to have been removed from the system, giant planets (if any) must have already been formed, and the formation of terrestrial planets may be on-going. Pluto-sized planetesimals, and their debris released in a collisional cascade, are under their mutual gravitational influence, which may result into non-axisymmetric structures in the debris disk. High angular resolution observations are required to investigate these effects and constrain the dynamical evolution of debris disks. Furthermore, multi-wavelength observations can provide information about the dust dynamics by probing different grain sizes. Here we present new VLT/SPHERE and ALMA observations of the debris disk around the 40 Myr old solar-type star HD 61005. We resolve the disk at unprecedented resolution both in the near-infrared (...

  1. Updates to the dust-agglomerate collision model and implications for planetesimal formation

    Science.gov (United States)

    Blum, Jürgen; Brisset, Julie; Bukhari, Mohtashim; Kothe, Stefan; Landeck, Alexander; Schräpler, Rainer; Weidling, René

    2016-10-01

    Since the publication of our first dust-agglomerate collision model in 2010, several new laboratory experiments have been performed, which have led to a refinement of the model. Substantial improvement of the model has been achieved in the low-velocity regime (where we investigated the abrasion in bouncing collisions), in the high-velocity regime (where we have studied the fragmentation behavior of colliding dust aggregates), in the erosion regime (in which we extended the experiments to impacts of small projectile agglomerates into large target agglomerates), and in the very-low velocity collision regime (where we studied further sticking collisions). We also have applied the new dust-agglomerate collision model to the solar nebula conditions and can constrain the potential growth of planetesimals by mass transfer to a very small parameter space, which makes this growth path very unlikely. Experimental examples, an outline of the new collision model, and applications to dust agglomerate growth in the solar nebula will be presented.

  2. Close stellar encounters with planetesimal discs The dynamics of asymmetry in the Beta Pictoris system

    CERN Document Server

    Larwood, J D

    2000-01-01

    We numerically investigate the dynamics of how a close stellar fly-by encounter of a symmetrical circumstellar planetesimal disc can give rise to the many kinds of asymmetries and substructures attributed to the edge-on dusty disc of Beta Pic. In addition we present new optical coronagraphic observations of the outer parts of Beta Pic's disc, and report that the radial extent is significantly greater than was found in previous measurements. The northeasterly extension of the disc's midplane is now measured out to 1835au from the star; the southwesterly component is measured out to 1450au. Hence we use the length asymmetry induced in a distribution of simulation test particles as the principal diagnostic feature when modelling the disc response, in order to constrain fly-by parameters. In particular we favour a low inclination prograde and near-parabolic orbit perturber of mass approximately 0.5 Solar masses. These initial conditions suggest that the perturber could have been physically associated with Beta Pi...

  3. Sublimation of Icy Planetesimals Around Main Sequence Stars--Common Dust Temperatures & Multiple Components

    Science.gov (United States)

    Morales, Farisa Y.; Rieke, G.; Werner, M.; Su, K.; Bryden, G.; Stapelfeldt, K.

    2011-01-01

    We compare the properties of warm dust emission from main-sequence A-type stars to those of dust around solar-type sources with similar Spitzer Space Telescope IRS/MIPS data and similar ages. Both samples have spectral energy distributions which show evidence of multiple components. Over the range of stellar types considered, we obtain nearly the same characteristic dust temperatures ( 190 K & 55 K for the inner & outer dust components respectively)--just above the ice line for the inner belts. The inner-belt temperature is readily explained if populations of grains are being released by sublimation of ice from icy planetesimals. Evaporation of comets at 170 K transports particles into an inner/warmer belt, where the super thermal grains left behind are found with Tdust >=190 K. 27 of the 50 A-type sources with warm excess are detected with Spitzer/MIPS at 70 µm (S/N > 3); the 50% rate of detection is comparable to the solar-type star sample where 9 of the 19 objects are also seen at MIPS 70 µm. This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under NASA contract 1407. Development of MIPS was funded by NASA through the Jet Propulsion Laboratory, subcontract 960785. This work was also partially supported by contract 1255094 from Caltech/JPL to the University of Arizona.

  4. Thermal evolution and sintering of chondritic planetesimals III. Modelling the heat conductivity of porous chondrite material

    CERN Document Server

    Henke, Stephan; Trieloff, Mario

    2016-01-01

    The construction of models for the internal constitution and the temporal evolution of large planetesimals, the parent bodies of chondrites, requires information on the heat conductivity of the complex mixture of minerals and iron metal found in chondrites. It is attempted to evaluate the heat conductivity of a multi-component mineral mixture and granular medium from the heat conductivities of its mixture components. Random mixtures of solids with chondritic composition and packings of spheres are numerically generated. The heat conduction equation is solved in high spatial resolution for a test cube filled with such matter. From the heat flux through the cube the heat conductivity of the mixture is derived. The model results for porous material are consistent with data for compacted sandstone, but are at odds with measurements for H and L chondrites. The discrepancy is traced back to shock modification of the currently available meteoritic material by impacts on the parent body over the last 4.5 Ga. This cau...

  5. Constraints on planetesimal disk mass from the cratering record and equatorial ridge on Iapetus

    Energy Technology Data Exchange (ETDEWEB)

    Rivera-Valentin, E. G.; Barr, A. C.; Lopez Garcia, E. J. [Department of Earth, Environmental, and Planetary Sciences, Brown University, 324 Brook Street, Box 1846, Providence, RI 02912 (United States); Kirchoff, M. R. [Southwest Research Institute, 1050 Walnut Street, Suite 200, Boulder, CO 80302 (United States); Schenk, P. M., E-mail: ervalentin@usra.edu [Lunar and Planetary Institute, 3600 Bay Area Boulevard, Houston, TX 77058 (United States)

    2014-09-10

    Iapetus, the outermost regular satellite of Saturn, has a drastic albedo dichotomy and an equatorial circumferential ridge that reaches heights of 20 km and widths of 70 km. This moon is thought to have formed concurrently with Saturn, and so would have experienced an intense bombardment after its formation. The ridge, which has been inferred to be one of the most ancient features on Iapetus' surface, could reasonably be expected to have been eroded by impacts; however, it has retained long continuous sections and a nearly pristine triangular shape with ridge slopes reaching ∼40°. We use these observations, along with crater counts on Iapetus' surface, to constrain the total bombardment mass experienced by the satellite since its formation. The ridge morphology and the global crater population recorded on Iapetus both suggest similar bombardment masses, indicating the ridge is indeed ancient. We find that the inferred total bombardment mass incident on Iapetus is less than 20% of the bombardment predicted by the classic Nice model for early solar system evolution. Our results, though, support the recently proposed scenarios of planetesimal-driven migration of the young outer planets including more realistic disk conditions.

  6. ASAS centennial paper: Contributions in the Journal of Animal Science to the development of protocols for breeding management of cattle through synchronization of estrus and ovulation.

    Science.gov (United States)

    Lauderdale, J W

    2009-02-01

    American Society of Animal Science members, publishing in Journal of Animal Science (JAS), completed research that resulted in understanding the estrous cycle of cattle, which led to the ability to inseminate cattle on a given day with pregnancy rates similar to those achieved by 21-d breeding by a fertile and sound bull. Research published in JAS led to understanding estrus, ovulation, the estrous cycle, and postpartum interval for cattle (1930s through 1960s) and hormonal factors affecting corpus luteum lifespan of cattle (1950s through 1980s). Research during the 1940s to 1960s, using gonadotropins and progesterone to manage the estrous cycle of cattle, established the concepts for estrous synchronization and stimulated commercial research directed at developing cost-effective progestogen estrous synchronization products, leading to commercially available products from 1967 through today (Repromix, melengestrol acetate, Syncro-Mate-B, controlled internal drug release). Prostaglandin F(2alpha) products were approved for estrous synchronization (1970s, 1980s), and GnRH products were approved for use in cattle to treat ovarian follicular cysts (1970s, 1980s). Research published in JAS was essential for understanding the biology of and potential value of both PGF(2alpha) and GnRH and contributed both to new knowledge and scientific bases for future Food and Drug Administration Center for Veterinary Medicine approval of those products. Research during the1980s through 2000s led to understanding ovarian follicular waves and described the timing of follicular recruitment, selection, dominance, and atresia; this research was essential for the ability to effectively manage follicles to achieve success with timed AI. The knowledge gained through research published in JAS resulted in development of the numerous estrous synchronization and breeding management protocols that are cost-effective and meet the breeding management needs of most beef and dairy enterprises.

  7. Time to unravel the conceptual confusion of authenticity and fidelity and their contribution to learning within simulation-based nurse education. A discussion paper.

    Science.gov (United States)

    Bland, Andrew J; Topping, Annie; Tobbell, Jane

    2014-07-01

    High-fidelity patient simulation is a method of education increasingly utilised by educators of nursing to provide authentic learning experiences. Fidelity and authenticity, however, are not conceptually equivalent. Whilst fidelity is important when striving to replicate a life experience such as clinical practice, authenticity can be produced with low fidelity. A challenge for educators of undergraduate nursing is to ensure authentic representation of the clinical situation which is a core component for potential success. What is less clear is the relationship between fidelity and authenticity in the context of simulation based learning. Authenticity does not automatically follow fidelity and as a result, educators of nursing cannot assume that embracing the latest technology-based educational tools will in isolation provide a learning environment perceived authentic by the learner. As nursing education programmes increasingly adopt simulators that offer the possibility of representing authentic real world situations, there is an urgency to better articulate and understand the terms fidelity and authenticity. Without such understanding there is a real danger that simulation as a teaching and learning resource in nurse education will never reach its potential and be misunderstood, creating a potential barrier to learning. This paper examines current literature to promote discussion within nurse education, concluding that authenticity in the context of simulation-based learning is complex, relying on far more than engineered fidelity.

  8. MAGNESIUM ISOTOPE EVIDENCE FOR SINGLE STAGE FORMATION OF CB CHONDRULES BY COLLIDING PLANETESIMALS

    Energy Technology Data Exchange (ETDEWEB)

    Olsen, Mia B.; Schiller, Martin; Krot, Alexander N.; Bizzarro, Martin [Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Copenhagen DK-1350 (Denmark)

    2013-10-10

    Chondrules are igneous spherical objects preserved in chondritic meteorites and believed to have formed during transient heating events in the solar protoplanetary disk. Chondrules present in the metal-rich CB chondrites show unusual chemical and petrologic features not observed in other chondrite groups, implying a markedly distinct formation mechanism. Here, we report high-precision Mg-isotope data for 10 skeletal olivine chondrules from the Hammadah al Hamra 237 (HH237) chondrite to probe the formation history of CB chondrules. The {sup 27}Al/{sup 24}Mg ratios of individual chondrules are positively correlated to their stable Mg-isotope composition (μ{sup 25}Mg), indicating that the correlated variability was imparted by a volatility-controlled process (evaporation/condensation). The mass-independent {sup 26}Mg composition (μ{sup 26}Mg*) of chondrules is consistent with single stage formation from an initially homogeneous magnesium reservoir if the observed μ{sup 25}Mg variability was generated by non-ideal Rayleigh-type evaporative fractionation characterized by a β value of 0.5142, in agreement with experimental work. The magnitude of the mass-dependent fractionation (∼300 ppm) is significantly lower than that suggested by the increase in {sup 27}Al/{sup 24}Mg values, indicating substantial suppression of isotopic fractionation during evaporative loss of Mg, possibly due to evaporation at high Mg partial pressure. Thus, the Mg-isotope data of skeletal chondrules from HH237 are consistent with their origin as melts produced in the impact-generated plume of colliding planetesimals. The inferred μ{sup 26}Mg* value of –3.87 ± 0.93 ppm for the CB parent body is significantly lower than the bulk solar system value of 4.5 ± 1.1 ppm inferred from CI chondrites, suggesting that CB chondrites accreted material comprising an early formed {sup 26}Al-free component.

  9. Mixing of Impactor Liquid Cores and Planetesimals Constrained by Single Silicate Crystal Magnetism

    Science.gov (United States)

    Bono, R. K.; Tarduno, J. A.; Nimmo, F.; Scott, E.; Ferrière, L.

    2014-12-01

    been a common process influencing the formation of planetesimals and protoplanets.

  10. Late Chondritic Additions and Planet and Planetesimal Growth: Evaluation of Physical and Chemical Mechanisms

    Science.gov (United States)

    Righter, Kevin

    2013-01-01

    Studies of terrestrial peridotite and martian and achondritic meteorites have led to the conclusion that addition of chondritic material to growing planets or planetesimals, after core formation, occurred on Earth, Mars, asteroid 4 Vesta, and the parent body of the angritic meteorites [1-4]. One study even proposed that this was a common process in the final stages of growth [5]. These conclusions are based almost entirely on the highly siderophile elements (HSE; Re, Au, Pt, Pd, Rh, Ru, Ir, Os). The HSE are a group of eight elements that have been used to argue for late accretion of chondritic material to the Earth after core formation was complete (e.g., [6]). This idea was originally proposed because the D(metal/silicate) values for the HSE are so high, yet their concentration in the mantle is too high to be consistent with such high Ds. The HSE also are present in chondritic relative abundances and hence require similar Ds if this is the result of core-mantle equilibration. Since the work of [6] there has been a realization that core formation at high PT conditions can explain the abundances of many siderophile elements in the mantle (e.g., [7]), but such detailed high PT partitioning data are lacking for many of the HSE to evaluate whether such ideas are viable for all four bodies. Consideration of other chemical parameters reveals larger problems that are difficult to overcome, but must be addressed in any scenario which calls on the addition of chondritic material to a reduced mantle. Yet these problems are rarely discussed or emphasized, making the late chondritic (or late veneer) addition hypothesis suspect.

  11. Iron and Stony-iron Meteorites: Evidence for the Formation, Crystallization, and Early Impact Histories of Differentiated Planetesimals

    DEFF Research Database (Denmark)

    Ruzicka, Alex M.; Haack, Henning; Chabot, Nancy L.

    2017-01-01

    By far most of the melted and differentiated planetesimals that have been sampled as meteorites are metal-rich iron meteorites or stony iron meteorites. The parent asteroids of these meteorites accreted early and differentiated shortly after the solar system formed, producing some of the oldest...... dated materials. The main heat source responsible for the melting and differentiation of asteroids was 26Al (Chapter 6, This Volume). Unlike the parent bodies of chondrites, the differentiated bodies accreted while 26Al was sufficiently abundant to cause melting. In this review, we summarize properties...

  12. Exploring Paper.

    Science.gov (United States)

    Brand, Judith, Ed.

    1999-01-01

    Exploratorium Magazine communicates ideas that exhibits cannot easily demonstrate, extending the museum beyond its physical walls. This issue takes an in-depth look at the science and history of paper. Topics include: (1) Fascinating Facts about Paper; (2) A Closer Look at the Paper in This Magazine; (3) Handmade Paper; (4) Paper Airplanes; (5)…

  13. Efficient paper recycling

    OpenAIRE

    Gregor-Svetec, Diana; Možina, Klemen; Blaznik, Barbara; Urbas, Raša; Vrabič Brodnjak, Urška; Golob, Gorazd

    2013-01-01

    Used paper and paper products are important raw material for paper and board industry. Paper recycling increases the material lifespan and is a key strategy that contributes to savings of primary raw material, reduction of energy and chemicals consumption, reduction of the impact on fresh water and improvement of waste management strategies. The paper recycling rate is still highly inhomogeneous among the countries of Central Europe. Since recovered paper is not only recycled in the country w...

  14. Insights into planet formation from debris disks: I. The solar system as an archetype for planetesimal evolution

    CERN Document Server

    Matthews, Brenda C

    2016-01-01

    Circumstellar disks have long been regarded as windows into planetary systems. The advent of high sensitivity, high resolution imaging in the submillimetre where both the solid and gas components of disks can be detected opens up new possibilities for understanding the dynamical histories of these systems and therefore, a better ability to place our own solar system, which hosts a highly evolved debris disk, in context. Comparisons of dust masses from protoplanetary and debris disks have revealed a stark downturn in mass in millimetre-sized grains around a stellar age of 10 Myr, ostensibly in the "transition disk" phase, suggesting a period of rapid accretion of such grains onto planetesimals. This rapid formation phase is in keeping with radionucleide studies of Kuiper Belt Objects in the solar system. Importantly, this suggests that any thermal gradients in the gas of disks of this era will be "frozen in" to the planetesimals as they rapidly accrete from the solids and ices in their vicinity. Measurements o...

  15. Insights into Planet Formation from Debris Disks: I. The Solar System as an Archetype for Planetesimal Evolution

    Science.gov (United States)

    Matthews, Brenda C.; Kavelaars, JJ

    2016-12-01

    Circumstellar disks have long been regarded as windows into planetary systems. The advent of high sensitivity, high resolution imaging in the submillimeter where both the solid and gas components of disks can be detected opens up new possibilities for understanding the dynamical histories of these systems and therefore, a better ability to place our own solar system, which hosts a highly evolved debris disk, in context. Comparisons of dust masses from protoplanetary and debris disks have revealed a stark downturn in mass in millimeter-sized grains around a stellar age of 10 Myr, ostensibly in the "transition disk" phase, suggesting a period of rapid accretion of such grains onto planetesimals. This rapid formation phase is in keeping with radionucleide studies of Kuiper Belt Objects in the solar system. Importantly, this suggests that any thermal gradients in the gas of disks of this era will be "frozen in" to the planetesimals as they rapidly accrete from the solids and ices in their vicinity. Measurements of radial gradients in thermal tracers such as DHO, DCN and other tracers can therefore provide insight into the nascent solar system's abundances. In studies of dynamical evolution of the solar system, it is tacitly assumed that such abundances can reveal the location of formation for bodies now found in the asteroid belt and Kuiper belt. Similarly, evidence of gas detected from collisional evolution in young debris disks could potentially reveal how rapidly objects have dynamically evolved in those systems, most of which will be significantly younger than the solar system.

  16. Paper electronics.

    Science.gov (United States)

    Tobjörk, Daniel; Österbacka, Ronald

    2011-05-03

    Paper is ubiquitous in everyday life and a truly low-cost substrate. The use of paper substrates could be extended even further, if electronic applications would be applied next to or below the printed graphics. However, applying electronics on paper is challenging. The paper surface is not only very rough compared to plastics, but is also porous. While this is detrimental for most electronic devices manufactured directly onto paper substrates, there are also approaches that are compatible with the rough and absorptive paper surface. In this review, recent advances and possibilities of these approaches are evaluated and the limitations of paper electronics are discussed.

  17. The Initial Mass and Size Distribution of Planetesimals. I. The Effect of Resolution, Gravity, and Initial Conditions in Streaming Instability Calculations

    CERN Document Server

    Simon, Jacob B; Li, Rixin; Youdin, Andrew N

    2015-01-01

    We study the formation of planetesimals in protoplanetary disks from the gravitational collapse of solid over-densities generated via the streaming instability. To carry out these studies, we implement and test a particle-mesh self-gravity module for the Athena code that enables the simulation of aerodynamically coupled systems of gas and collisionless self-gravitating solid particles. Upon employment of our algorithm to planetesimal formation simulations, we find that (when a direct comparison is possible) the Athena simulations yield predicted planetesimal properties that agree well with those found in prior work using different numerical techniques. In particular, the gravitational collapse of streaming-initiated clumps leads to an initial planetesimal mass function that is well-represented by a power-law, dN/dM ~ M^(-p),with p = 1.6 +/- 0.1. We find no significant trends with resolution from a convergence study of up to 512^3 grid zones and N_par ~ 1.5x10^8 particles. Likewise, the power-law slope appears...

  18. Coagulation calculations of icy planet formation around 0.1-0.5 M {sub ☉} stars: Super-Earths from large planetesimals

    Energy Technology Data Exchange (ETDEWEB)

    Kenyon, Scott J. [Smithsonian Astrophysical Observatory, 60 Garden Street, Cambridge, MA 02138 (United States); Bromley, Benjamin C., E-mail: skenyon@cfa.harvard.edu, E-mail: bromley@physics.utah.edu [Department of Physics, University of Utah, 201 JFB, Salt Lake City, UT 84112 (United States)

    2014-01-01

    We investigate formation mechanisms for icy super-Earth-mass planets orbiting at 2-20 AU around 0.1-0.5 M {sub ☉} stars. A large ensemble of coagulation calculations demonstrates a new formation channel: disks composed of large planetesimals with radii of 30-300 km form super-Earths on timescales of ∼1 Gyr. In other gas-poor disks, a collisional cascade grinds planetesimals to dust before the largest planets reach super-Earth masses. Once icy Earth-mass planets form, they migrate through the leftover swarm of planetesimals at rates of 0.01-1 AU Myr{sup –1}. On timescales of 10 Myr to 1 Gyr, many of these planets migrate through the disk of leftover planetesimals from semimajor axes of 5-10 AU to 1-2 AU. A few percent of super-Earths might migrate to semimajor axes of 0.1-0.2 AU. When the disk has an initial mass comparable with the minimum-mass solar nebula, scaled to the mass of the central star, the predicted frequency of super-Earths matches the observed frequency.

  19. Rapid Coagulation of Porous Dust Aggregates Outside the Snow Line: A Pathway to Successful Icy Planetesimal Formation

    CERN Document Server

    Okuzumi, Satoshi; Kobayashi, Hiroshi; Wada, Koji

    2012-01-01

    Rapid orbital drift of macroscopic dust particles is one of the major obstacles against planetesimal formation in protoplanetary disks. We reexamine this problem by considering porosity evolution of dust aggregates. We apply a porosity model based on recent N-body simulations of aggregate collisions, which allows us to study the porosity change upon collision for a wide range of impact energies. As a first step, we neglect collisional fragmentation and instead focus on dust evolution outside the snow line, where the fragmentation has been suggested to be less significant than inside the snow line because of a high sticking efficiency of icy particles. We show that dust particles can evolve into highly porous aggregates (with internal densities of much less than 0.1 g/cm^3) even if collisional compression is taken into account. We also show that the high porosity triggers significant acceleration in collisional growth. This acceleration is a natural consequence of particles' aerodynamical property at low Knuds...

  20. Audio Papers

    DEFF Research Database (Denmark)

    Groth, Sanne Krogh; Samson, Kristine

    2016-01-01

    With this special issue of Seismograf we are happy to present a new format of articles: Audio Papers. Audio papers resemble the regular essay or the academic text in that they deal with a certain topic of interest, but presented in the form of an audio production. The audio paper is an extension...... of the written paper through its specific use of media, a sonic awareness of aesthetics and materiality, and creative approach towards communication. The audio paper is a performative format working together with an affective and elaborate understanding of language. It is an experiment embracing intellectual...... arguments and creative work, papers and performances, written scholarship and sonic aesthetics. For this special issue of Seismograf, the guidelines for authors and peer reviewers mainly focused on the format. Topic-wise we encouraged dealing with site-specificity and topics related to the island Amager...

  1. "Paper" airplanes

    National Research Council Canada - National Science Library

    2005-01-01

    ... the suggestion came from the custodian, who got his idea from an unlikely place. "You know how toilet paper always has holes in it?" he told the company president. "Well, I noticed that it never tears there. I figured if it works on toilet paper, it would work on a plane."...

  2. PAPER LANDSCAPES

    Institute of Scientific and Technical Information of China (English)

    Lorna Mansley

    2008-01-01

    <正>Take a sheet of paper, a pair of scissors or a knife, a vivid imagination and see what you can create. Synonymous with Chinese folkart, paper cutting no longer seems to be a flourishing craft amongst China’s younger generations of creatives, though its motifs can

  3. Selected papers

    CERN Document Server

    Tamm, I E; Frenkel, V Ya

    1991-01-01

    I.E. Tamm is one of the great figures of 20th-century physics and the mentor of the late A.D. Sakharov. Together with I.M. Frank, he received the Nobel Prize in 1958 for the explanation of the Cherenkov effect. This book contains an annotated selection of his most important contributions to physics literature and essays on his contemporaries - Mandelstam, Einstein, Landau and Bohr as well as his contributions to the Pugwash conferences. About a third of the selections originally appeared in Russian and are now available to Western readers. This volume includes a preface by Sir Rudolf Peierls, a biography compiled by Tamm's former students, V.Ya. Frenkel and B.M. Bolotovskii, and a complete bibliography. This monograph on quantum theory, science history, particles and fields and the Cherenkov effect is intended for students, researchers, mathematicians and natural scientists in general.

  4. 应用层次分析法研究生物医学论文作者的贡献%Apportionment of co-authors' contribution for a biomedical scientific paper: An analytical process approach

    Institute of Scientific and Technical Information of China (English)

    陈维进; 罗鹏程; 张杰

    2014-01-01

    Objective To determine co-author contribution for a biomedical scientific paper describing collaborative research by an analytical process model.Methods The important features of contribution were identified,categorized and organized into a logical hierarchy consisting of the main dimensions and sub-dimensions.A face-to-face survey was conducted to obtain data about their relative importance from co-authors.Analytical hierarchy process methodology was used to determine the relative important weights from main dimensions and sub-dimensions along with the consistency.Results Among the 5 main dimensions,all authors considered problem statement as the most important with a weight of 0.4355,and considered research design and data analysis taking the 2nd and 3rd positions.Among the 10 sub-dimensions,hypothesis construction,method development,result interpretation,and critical revision of manuscript were considered the most important contributions.Conclusion Analytical hierarchy process effectively supportto establish the co-authors' priorties for a biomedical scientific paper.%目的 应用层次分析法研究生物医学论文作者的贡献.方法 确定生物医学论文的贡献之处的重要指标,再将这些指标分类、整理成层级化的结构.应用层次分析法确定层级化结构一级指标和二级指标的贡献权重值,权重值通过一致性检验即是下次指标对上级指标的贡献值.结果 在5个初级维度指标,提出科学问题的贡献值最大,为0.4355,其次为设计方案和分析数据,贡献值分别是0.2873和0.1521.在10个次级维度指标中,建立假设、制定方案、解释数据和修订文稿的贡献值较大,分别为0.9、0.6667、0.8和0.833.结论 层次分析法可有效量化生物医学论文作者的贡献.

  5. Mathematical papers

    CERN Document Server

    Green, George

    2005-01-01

    An almost entirely self-taught mathematical genius, George Green (1793 -1841) is best known for Green's theorem, which is used in almost all computer codes that solve partial differential equations. He also published influential essays, or papers, in the fields of hydrodynamics, electricity, and magnetism. This collection comprises his most significant works.The first paper, ""An Essay on the Application of Mathematical Analysis to the Theories of Electricity and Magnetism,"" which is also the longest and perhaps the most Important, appeared In 1828. It introduced the term potential as desig

  6. Panama Papers

    DEFF Research Database (Denmark)

    Harrington, Brooke

    2016-01-01

    Mossack Fonseca kept its clients largely on the right side of the law. Indeed, that’s entirely the point. This article for The Atlantic draws on my wealth management research to explain why most of what is revealed in the Panama Papers leak will not result in criminal prosecution for anyone...

  7. Paper works

    DEFF Research Database (Denmark)

    Rasmussen, Mattias Borg

    2017-01-01

    of their land and natural resources, but also of labor and territorial sovereignty. This case shows how an Andean campesino community counters such movements by a wide repertoire of legal and social actions that works simultaneously in legal and extra-legal domains. Paper works mediate claims to territorial...

  8. Panama Papers

    DEFF Research Database (Denmark)

    Harrington, Brooke

    2016-01-01

    Mossack Fonseca kept its clients largely on the right side of the law. Indeed, that’s entirely the point. This article for The Atlantic draws on my wealth management research to explain why most of what is revealed in the Panama Papers leak will not result in criminal prosecution for anyone...

  9. Collected Papers

    CERN Document Server

    Kostant, Bertram; Kumar, Shrawan; Vergne, Michele

    2009-01-01

    The author has been one of the major architects of modern Lie theory. His interests span a tremendous range of Lie theory, from differential geometry to representation theory, abstract algebra, and mathematical physics. This title features commentaries and summaries of his papers in his own words.

  10. Panama Papers

    DEFF Research Database (Denmark)

    Harrington, Brooke

    2016-01-01

    Mossack Fonseca kept its clients largely on the right side of the law. Indeed, that’s entirely the point. This article for The Atlantic draws on my wealth management research to explain why most of what is revealed in the Panama Papers leak will not result in criminal prosecution for anyone......, and why government officials face nearly insurmountable obstacles to stopping the kind of financial games in which Mossack Fonseca and its counterparts engage....

  11. Immiscible silicate liquids and phosphoran olivine in Netschaëvo IIE silicate: Analogue for planetesimal core-mantle boundaries

    Science.gov (United States)

    Van Roosbroek, Nadia; Hamann, Christopher; McKibbin, Seann; Greshake, Ansgar; Wirth, Richard; Pittarello, Lidia; Hecht, Lutz; Claeys, Philippe; Debaille, Vinciane

    2017-01-01

    We have investigated a piece of the Netschaëvo IIE iron meteorite containing a silicate inclusion by means of electron microprobe analysis (EMPA) and transmission electron microscopy (TEM). Netschaëvo contains chondrule-bearing clasts and impact melt rock clasts were also recently found. The examined inclusion belongs to the latter and is characterized by a porphyritic texture dominated by clusters of coarse-grained olivine and pyroxene, set in a fine-grained groundmass that consists of new crystals of olivine and a hyaline matrix. This matrix material has a quasi-basaltic composition in the inner part of the inclusion, whereas the edge of the inclusion has a lower SiO2 concentration and is enriched in MgO, P2O5, CaO, and FeO. Close to the metal host, the inclusion also contains euhedral Mg-chromite crystals and small (olivine crystallites containing up to 14 wt% P2O5, amorphous material, and interstitial Cl-apatite crystals. The Si-rich silicate glass globules show a second population of Fe-rich silicate glass droplets, indicating they formed by silicate liquid immiscibility. Together with the presence of phosphoran olivine and quenched Cl-apatite, these textures suggest rapid cooling and quenching as a consequence of an impact event. Moreover, the enrichment of phosphorus in the silicate inclusion close to the metal host (phosphoran olivine and Cl-apatite) indicates that phosphorus re-partitioned from the metal into the silicate phase upon cooling. This probably also took place in pallasite meteorites that contain late-crystallizing phases rich in phosphorus. Accordingly, our findings suggest that oxidation of phosphorus might be a general process in core-mantle environments, bearing on our understanding of planetesimal evolution. Thus, the Netschaëvo sample serves as a natural planetesimal core-mantle boundary experiment and based on our temperature estimates, the following sequence of events takes place: (i) precipitation of olivine (1400-1360 °C), (ii) re

  12. Selected papers

    CERN Document Server

    Elgot, Calvin C

    1982-01-01

    Cal Elgot was a very serious and thoughtful researcher, who with great determi­ nation attempted to find basic explanations for certain mathematical phenomena­ as the selection of papers in this volume well illustrate. His approach was, for the most part, rather finitist and constructivist, and he was inevitably drawn to studies of the process of computation. It seems to me that his early work on decision problems relating automata and logic, starting with his thesis under Roger Lyndon and continuing with joint work with Biichi, Wright, Copi, Rutledge, Mezei, and then later with Rabin, set the stage for his attack on the theory of computation through the abstract treatment of the notion of a machine. This is also apparent in his joint work with A. Robinson reproduced here and in his joint papers with John Shepherdson. Of course in the light of subsequent work on decision problems by Biichi, Rabin, Shelah, and many, many others, the subject has been placed on a completely different plane from what it was whe...

  13. Paper justice.

    Science.gov (United States)

    Culler, T A

    2000-01-01

    This article relates the case of two young girls who became pregnant as a result of rape and their efforts to exercise their rights to terminate the pregnancy. The first victim was a 12-year-old girl from Bolivia and the second was Paulina, a 13-year-old resident of Baja California, Mexico. Though abortion is illegal in both countries, in the case of rape the procedure is "unpunishable" in Bolivia and legal in Mexico. Despite these laws, the girls, their families and their advocates contend repeatedly with local government and Catholic Church officials on the issue. Only the first victim successfully exercised her right to terminate her pregnancy through the efforts of her family and the decision of Penal Judge Luis Ledezma. This paper also highlights the need for reforms in the abortion law in both countries.

  14. From Planetesimals to Dust: Low Gravity Experiments on Recycling Solids at the Inner Edge of Protoplanetary Disks

    CERN Document Server

    De Beule, Caroline; Wurm, Gerhard; Teiser, Jens; Jankowski, Tim; 10.1088/0004-637X/763/1/11

    2013-01-01

    Transporting solids of different sizes is an essential process in the evolution of protoplanetary disks and planet formation. Large solids are supposed to drift inward; high-temperature minerals found in comets are assumed to have been transported outward. From low-gravity experiments on parabolic flights we studied the light-induced erosion of dusty bodies caused by a solid-state greenhouse effect and photophoresis within a dust bed's upper layers. The gravity levels studied were 0.16g, 0.38g, 1g, and 1.7g. The light flux during the experiments was 12 +/- 2 kW/m^2 and the ambient pressure was 6 +/- 0.9 mbar. Light-induced erosion is strongly gravity dependent, which is in agreement with a developed model. In particular for small dusty bodies ((sub)-planetesimals), efficient erosion is possible at the optically thin inner edges of protoplanetary disks. Light-induced erosion prevents significant parts of a larger body from moving too close to the host star and be being subsequently accreted. The small dust pro...

  15. Forming Planetesimals by Gravitational Instability: I. The Role of the Richardson Number in Triggering the Kelvin-Helmholtz Instability

    CERN Document Server

    Lee, Aaron T; Asay-Davis, Xylar; Barranco, Joseph

    2010-01-01

    Gravitational instability (GI) of a dust-rich layer at the midplane of a gaseous circumstellar disk is one proposed mechanism to form planetesimals, the building blocks of rocky planets and gas giant cores. Self-gravity competes against the Kelvin-Helmholtz instability (KHI): gradients in dust content drive a vertical shear which risks overturning the dusty subdisk and forestalling GI. To understand the conditions under which the disk can resist the KHI, we perform 3D simulations of stratified subdisks in the limit that dust particles are small and aerodynamically well coupled to gas. This limit screens out the streaming instability and isolates the KHI. Each subdisk is assumed to have a vertical density profile given by a spatially constant Richardson number Ri. We vary Ri and the midplane dust-to-gas ratio mu and find that the critical Richardson number dividing KH-unstable from KH-stable flows is not unique; rather Ri_crit grows nearly linearly with mu for mu=0.3-10. Only for disks of bulk solar metallicit...

  16. Planetesimal clearing and size-dependent asteroid retention by secular resonance sweeping during the depletion of the solar nebula

    CERN Document Server

    Zheng, Xiaochen; Kouwenhoven, M B N

    2016-01-01

    The distribution of heavy elements is anomalously low in the asteroid main belt region compared with elsewhere in the solar system. Observational surveys also indicate a deficit in the number of small ($ \\le 50$~km size) asteroids that is two orders of magnitude lower than what is expected from the single power-law distribution that results from a collisional coagulation and fragmentation equilibrium. Here, we consider the possibility that a major fraction of the original asteroid population may have been cleared out by Jupiter's secular resonance, as it swept through the main asteroid belt during the depletion of the solar nebula. This effect leads to the excitation of the asteroids' orbital eccentricities. Concurrently, hydrodynamic drag and planet-disk tidal interaction effectively damp the eccentricities of sub-100 km-size and of super-lunar-size planetesimals, respectively. These combined effects lead to the asteroids' orbital decay and clearing from the present-day main belt region ($\\sim 2.1-3.3$~AU). ...

  17. High-speed photometry of the disintegrating planetesimals at WD1145+017: evidence for rapid dynamical evolution

    CERN Document Server

    Gaensicke, B T; Marsh, T R; Dhillon, V S; Sahman, D I; Veras, Dimitri; Farihi, J; Chote, P; Ashley, R; Arjyotha, S; Rattanasoon, S; Pollacco, D; Burleigh, M R

    2016-01-01

    We obtained high-speed photometry of the disintegrating planetesimals orbiting the white dwarf WD1145+017, spanning a period of four weeks. The light curves show a dramatic evolution of the system since the first observations obtained about seven months ago. Multiple transit events are detected in every light curve, which have varying durations(~3-12min) and depths (~10-60%). The shortest-duration transits require that the occulting cloud of debris has a few times the size of the white dwarf, longer events are often resolved into the superposition of several individual transits. The transits evolve on time scales of days, both in shape and in depth, with most of them gradually appearing and disappearing over the course of the observing campaign. Several transits can be tracked across multiple nights, all of them recur on periods of ~4.49h, indicating multiple planetary debris fragments on nearly identical orbits. Identifying the specific origin of these bodies within this planetary system, and the evolution l...

  18. From dust to planetesimals: an improved model for collisional growth in protoplanetary disks

    CERN Document Server

    Garaud, Pascale; Galvagni, Marina; Olczak, Christoph

    2012-01-01

    Planet formation occurs within the gas and dust rich environments of protoplanetary disks. Observations of these objects show that the growth of primordial sub micron sized particles into larger aggregates occurs at the earliest stages of the disks. However, theoretical models of particle growth that use the Smoluchowski equation to describe collisional coagulation and fragmentation have so far failed to produce large particles while maintaining a significant populations of small grains. This has been generally attributed to the existence of two barriers impeding growth due to bouncing and fragmentation of colliding particles. In this paper, we demonstrate that the importance of these barriers has been artificially inflated through the use of simplified models that do not take into account the stochastic nature of the particle motions within the gas disk. We present a new approach in which the relative velocities between two particles is described by a probability distribution function that models both determ...

  19. Addenda to the Preceding Paper

    Science.gov (United States)

    Bhatnagar, Rajat; Finn, Robert

    2016-12-01

    This work contains largely afterthoughts, relating to the paper immediately preceding it. We correlate and interpret our contributions in that paper, relative to those of an earlier publication by Aspley, He and McCuan. We propose specific laboratory experiments, suggested by formal predictions of those two papers.

  20. Proceedings of the NATO-Advanced Study Institute on Computer Aided Analysis of Rigid and Flexible Mechanical Systems Held in Troia, Portugal on 27 Jun-9 Jul, 1993. Volume 2. Contributed Papers

    Science.gov (United States)

    1993-07-09

    inearized locally (compare Skelton, 1988. Hahn. 1986). The contro) concept investigated in this paper is based on exact linearization of the nonlinear...sutratiansed as follows- - Test of exact linearization conditions * Construction of a nonlinear state transformation (diffeomorphism) - Mapping of nonlinear...lineartzation) * pole placement of the exact linearized control plant via linear state feedback (stabilisation). 3.1 TEST OF EXACT LINEARIZATION CONDITIONS

  1. 26Al- 26Mg deficit dating ultramafic meteorites and silicate planetesimal differentiation in the early Solar System?

    Science.gov (United States)

    Baker, Joel A.; Schiller, Martin; Bizzarro, Martin

    2012-01-01

    =+0.0015±0.0020‰, which is identical to terrestrial olivine. Model ages from these deficits can be calculated by assuming that 26Al was homogeneously distributed in the planetesimal-forming regions of the proto-planetary disc at the same level as calcium-aluminium-rich inclusions (CAIs). The absence of 26Mg deficits in aubrites, means these can only be constrained to have formed relatively late >2.9 Myr after CAI formation. Model ages calculated from pallasite olivine deficits would suggest that pallasite olivine crystallised and was diffusively isolated on its parent body 1.24-0.28+0.40 Myr after formation of CAIs. Similarly, ureilites would have experienced silicate partial melting and lowering of their bulk Al/Mg ratios 1.9-0.7+2.2 Myr after CAI formation. The model ages for silicate differentiation on the main group pallasite parent body are intermediate between those for metal-silicate fractionation for core formation obtained from magmatic iron meteorites and those for asteroidal silicate magmatism obtained from basaltic meteorites.

  2. Study of cis- and trans-uranium elements by paper chromatography and electrophoresis; Contribution a l'etude des elements cis- et trans-uraniens par chromatographie sur papier et electrophorese

    Energy Technology Data Exchange (ETDEWEB)

    Clanet, F. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-01-01

    In this work, the field of application of paper chromatography and electrophoresis in inorganic chemistry has been extended to elements 90 to 96 in hydrochloric and nitric acid solution. Results obtained concern the following points: 1) - Characterization of the valency states of Np and of Pu using coloured reactions on chromatograms and electrophoregrams. The valency IV is characterized by alizarin, arsenazo-I and thorin-I, whilst diphenylcarbazide is used for the hexavalent state. 2) - Paper chromatography: by using as eluent, mixtures of equal parts of aqueous HCl and HNO{sub 3} solutions and of alcohols (methanol, ethanol and n-butanol), the R{sub f} values of elements 90 to 96 have been determined. It has been possible to deduce certain conclusions concerning the complexing of these elements by Cl{sup -} and NO{sub 3}{sup -} ions. 3) - We have developed an electrophoretic technique on cellulose acetate membranes in order to separate the charged species formed by the elements 90 to 96 in HCl and HNO{sub 3} solutions from 1 to 12 M. Mobility curves have been obtained. It appears from our results that the tendency for the elements considered to form anionic complexes follows the order of the ionic potentials when the valency state is four; this order is reversed for the valency three. The ions Cl{sup -} have a smaller tendency to form complexes than the NO{sub 3}{sup -} ions with respect to these elements in their oxidation state III or IV, but the reverse phenomenon is observed for U{sup VI} and Pu{sup VI}. Finally, the complexing of the cations Pu{sup 4+} and PuUO{sub 2}{sup 2+} by NO{sub 3}{sup -} follows the order of the ionic potentials but occurs in the reverse order for Cl{sup -} ions. 4) - Various analytical applications are considered: separation of the various elements from each other and separation of the valency states of Np and of Pu. (author) [French] Dans cette etude, le champ d'application de la chromatographie sur papier et de l

  3. Discussion on the paper entitled "Indian Contribution in the Field of Palaeo-oceanography (2006-2012)" by A K Gupta et al., 2012. Proc Indian Nat Sci Acad Vol. 78, No. 3 (IUGS Special Issue) pp. 313-319: Serious flaws in the status report on Indian palaeoceanography

    Digital Repository Service at National Institute of Oceanography (India)

    Banakar, V.K.

    published papers, which are based on sediment cores collected by several Indian researchers on-board the Indian research vessels”. The third paragraph of Banakar’s comments again raises the question of not incorporating some references. Also he has mentioned... Discussion Discussion on the paper entitled “Indian Contribution in the Field of Palaeo-oceanography (2006-2012)” by A K Gupta et al., 2012. Proc Indian Nat Sci Acad Vol. 78, No. 3 (IUGS Special Issue) pp. 313-319 Discussion: Serious Flaws in the Status...

  4. Robotic Arms. A Contribution to the Curriculum. An Occasional Paper.

    Science.gov (United States)

    Arnold, W. F.; Carpenter, C. J.

    This report examines ways of providing technician training in the operating principles of robotic devices. The terms "robotics" and "robotic arms" are first defined. Some background information on the principal features of robotic arms is given, including their geometric arrangement, type of actuator used, control method, and…

  5. Social Contributions in Romania

    Directory of Open Access Journals (Sweden)

    Attila Gyorgy

    2012-12-01

    Full Text Available Social contributions have an important impact on payroll policy. Also, social contributions represent a significant budgetary revenue item which can be viewed at the edge between taxation and insurance. Social contributions in Romania experienced many changes which ended in 2008. Nowadays, they are within a long transaction period towards partial externalization of the insurance activity to privately managed funds. The aim of this paper is to analyse the homogeneity of Romanian social security public scheme using annual data extracted from 2002-2009.The main findings reveal that social contributions reached the pinnacle of diversification, being too many, some of them with a small contribution rates; fiscal reforms which reduced contribution rates advantaged employers, and state will be interested to externalize this activity as far private sector will be able to assume this responsibility and the budgetary effects are acceptable for the public finance.

  6. INTRODUCTION Summary of Papers Summary of Papers

    Science.gov (United States)

    Gauthier, Serge; Abarzhi, Snezhana I.; Sreenivasan, Katepalli R.

    2010-12-01

    review various aspects of Turbulent Mixing that were discussed at the Second International Conference and Advanced School 'Turbulent Mixing and Beyond', TMB-2009, held in summer 2009 at the Abdus Salam International Centre for Theoretical Physics (ICTP), Trieste, Italy. The papers are arranged by TMB themes and within each theme they are ordered alphabetically by the last name of the first author, with tutorials following research contributions. Canonical turbulence and turbulent mixing. The theme of canonical turbulence and turbulent mixing is considered by several authors. Casciola et al investigate the dynamics of inertial particles dispersed in a turbulent jet and compare their numerical modeling results with the classical similarity theory of the jet far-field. Remarkable agreement is found between the theory and the direct numerical simulations (DNS), including decay of Stokes numbers with the distance from the origin, self-similarity of the mean axial particle velocity profile, etc. Nagata considers complex turbulent flows, which are known to exhibit no linear critical point for the laminar states, and which are linearly stable at finite Reynolds numbers. Square duct flow and sliding Couette flow in an annulus are considered and nonlinear traveling-wave states are found for the flows with the use of the homotopy approach developed by the author. These states may constitute a skeleton around which a time-dependent trajectory in the phase space is organized. Teitelbaum and Mininni study a decaying 3D incompressible turbulence, which mimicks turbulent mixing in geophysical flows, with rotation rendering the flow anisotropic at large scales. The authors analyze three DNS results (without and with rotation, and with helicity), observe a decoupling of the modes normal to the rotation axis, and show that the helicity decreases the decay rate of turbulence. Wang and Peters investigate the structure of turbulence by studying strain rates of various scalars, including a

  7. The Migrant Papers. Behavorial Science Working Paper.

    Science.gov (United States)

    Harrison, Ira E.

    Four papers pertaining to health services for East Coast migrant workers are included in this publication. These papers are: (1) "The Crew Leader as a Broker with Implications for Health Service Delivery," (2) "Migrant Health Project with Implications for Health Service Delivery," (3) "Planned Change in a Migrant Health…

  8. Rabi N. Bhattacharya selected papers

    CERN Document Server

    Waymire, Edward

    2016-01-01

    This volume presents some of the most influential papers published by Rabi N. Bhattacharya, along with commentaries from international experts, demonstrating his knowledge, insight, and influence in the field of probability and its applications. For more than three decades, Bhattacharya has made significant contributions in areas ranging from theoretical statistics via analytical probability theory, Markov processes, and random dynamics to applied topics in statistics, economics, and geophysics. Selected reprints of Bhattacharya’s papers are divided into three sections: Modes of Approximation, Large Times for Markov Processes, and Stochastic Foundations in Applied Sciences. The accompanying articles by the contributing authors not only help to position his work in the context of other achievements, but also provide a unique assessment of the state of their individual fields, both historically and for the next generation of researchers. Rabi N. Bhattacharya: Selected Papers will be a valuable resource for yo...

  9. The role of material strength in collisions -- Comparing solid body and hydrodynamic physics for simulating collisions of planetesimals with icy shells

    CERN Document Server

    Maindl, Thomas I; Speith, Roland; Schäfer, Christoph

    2014-01-01

    Context. We investigate the effects of including material strength in multi-material planetesimal collisions. Aims. The differences between strengthless material models and including the full elasto-plastic model for solid bodies with brittle failure and fragmentation when treating collisions of asteroid-sized bodies as they occur frequently in early planetary systems are demonstrated. Methods. We study impacts of bodies of Ceres-mass with a solid rock target and an impactor with 30 wt% water content. The initial impact velocities and impact parameters are varied between the escape velocity $v_\\mbox{esc}$ to about 6 $v_\\mbox{esc}$ and from head-on collisions to close fly-bys, respectively. We simulate the collisions using our own SPH code using both strengthless material and the full elasto-plastic material model including brittle failure. Results. The qualitative analysis results in significant differences depending on whether material strength is included or not. This may be an effect of the relatively low-...

  10. Paper on Designing Costless THz Paper Optics

    Directory of Open Access Journals (Sweden)

    A. Siemion

    2016-01-01

    Full Text Available Designing diffractive optical elements is crucial for efficient development of THz techniques. Here, we consider paper structures and we analyze their advantages and disadvantages in fast prototyping. The discussion about using material parameters like refractive index and absorption coefficient in designing diffractive optical elements is shown. We analyze the influence of phase step mismatch, of attenuation of real structure, and of nonuniform illumination on the efficiency of the structure. All these features result in worsening of the diffraction efficiency but they do not seem to have such significant influence as shadow effect introduced by fast varying zones. Diffractive elements can be designed with very good accordance with experimental results which makes them ideal for possible applications. Paper optics scan be used more for fast prototyping; nevertheless its performance can be increased by placing it inside water protecting foil.

  11. Audio Papers - A Manifesto

    DEFF Research Database (Denmark)

    Krogh Groth, Sanne; Samson, Kristine

    2016-01-01

    Audio papers resemble the regular essay or the academic text in that they deal with a certain topic of interest, but presented in the form of an audio production. The audio paper is an extension of the written paper through its specific use of media, a sonic awareness of aesthetics and materiality......, and creative approach towards communication. The audio paper is a performative format working together with an affective and elaborate understanding of language. It is an experiment embracing intellectual arguments and creative work, papers and performances, written scholarship and sonic aesthetics....

  12. The physics of paper

    Energy Technology Data Exchange (ETDEWEB)

    Alava, Mikko [Helsinki University of Technology, Laboratory of Physics, PO Box 1100, 02015 HUT (Finland); Niskanen, Kaarlo [KCL Science and Consulting, PO Box 70, 02150 Espoo (Finland)

    2006-03-01

    Paper is a material known to everybody. It has a network structure consisting of wood fibres that can be mimicked by cooking a portion of spaghetti and pouring it on a plate, to form a planar assembly of fibres that lie roughly horizontal. Real paper also contains other constituents added for technical purposes. This review has two main lines of thought. First, in the introductory part, we consider the physics that one encounters when 'using' paper, an everyday material that exhibits the presence of disorder. Questions arise, for instance, as to why some papers are opaque and others translucent, some are sturdy and others sloppy, some readily absorb drops of liquid while others resist the penetration of water. The mechanical and rheological properties of paper and paperboard are also interesting. They are inherently dependent on moisture content. In humid conditions paper is ductile and soft, in dry conditions brittle and hard. In the second part we explain in more detail research problems concerned with paper. We start with paper structure. Paper is made by dewatering a suspension of fibres starting from very low content of solids. The processes of aggregation, sedimentation and clustering are familiar from statistical mechanics. Statistical growth models or packing models can simulate paper formation well and teach a lot about its structure. The second research area that we consider is the elastic and viscoelastic properties and fracture of paper and paperboard. This has traditionally been the strongest area of paper physics. There are many similarities to, but also important differences from, composite materials. Paper has proved to be convenient test material for new theories in statistical fracture mechanics. Polymer physics and memory effects are encountered when studying creep and stress relaxation in paper. Water is a 'softener' of paper. In humid conditions, the creep rate of paper is much higher than in dry conditions. The third among

  13. Robotics Strategy White Paper

    Science.gov (United States)

    2009-03-19

    VIRGINIA 23651-1087 REPlY TO A1Tl!NTlON OF ATFC-DS 19 MEMORANDUM FOR SEE DISTRIBUTION SUBJECT: Robotics Strategy White Paper 1. The enclosed... Robotics Strategy White Paper is the result of a collaborative effort between the U.S. Anny Training and Doctrine Command (TRADOC) and the Tank-Automotive...Research, Development and Engineering Center (TARDEC). This paper builds on a confederated Anny robotics "strategy" that is described by senior leader

  14. Writing A Research Paper

    OpenAIRE

    Cennetkusu, Nazmiye Gürel

    2012-01-01

    Writing a research paper in English as a foreign language for the first time is a challenging task for many international doctoral students. This study explores the challenges experienced and strategies utilized during the academic socialization process through research paper writing and within the framework of sociocultural theory. The results indicate that limited experience in research paper writing and personal writing style with cultural influence are the most challenging aspects. The ut...

  15. Malaysia; Background Paper

    OpenAIRE

    International Monetary Fund

    1996-01-01

    This Background Paper on Malaysia examines developments and trends in the labor market since the mid-1980s. The paper describes the changes in the employment structure and the labor force. It reviews wages and productivity trends and their effects on unit labor cost. The paper highlights that Malaysia’s rapid growth, sustained since 1987, has had a major impact on the labor market. The paper outlines the major policy measures to address the labor constraints. It also analyzes Malaysia’s r...

  16. Paper based electronics platform

    KAUST Repository

    Nassar, Joanna Mohammad

    2017-07-20

    A flexible and non-functionalized low cost paper-based electronic system platform fabricated from common paper, such as paper based sensors, and methods of producing paper based sensors, and methods of sensing using the paper based sensors are provided. A method of producing a paper based sensor can include the steps of: a) providing a conventional paper product to serve as a substrate for the sensor or as an active material for the sensor or both, the paper product not further treated or functionalized; and b) applying a sensing element to the paper substrate, the sensing element selected from the group consisting of a conductive material, the conductive material providing contacts and interconnects, sensitive material film that exhibits sensitivity to pH levels, a compressible and/or porous material disposed between a pair of opposed conductive elements, or a combination of two of more said sensing elements. The method of sensing can further include measuring, using the sensing element, a change in resistance, a change in voltage, a change in current, a change in capacitance, or a combination of any two or more thereof.

  17. Fun with Paper Chromatography.

    Science.gov (United States)

    Coleman, Dava; Hounshell, Paul B.

    1982-01-01

    Discusses paper chromatographic techniques and provides examples of typical classroom activities. Includes description of retardation values obtained during chromatography exercises and suggests using them for math lessons. (JN)

  18. Protein crystallization with paper

    Science.gov (United States)

    Matsuoka, Miki; Kakinouchi, Keisuke; Adachi, Hiroaki; Maruyama, Mihoko; Sugiyama, Shigeru; Sano, Satoshi; Yoshikawa, Hiroshi Y.; Takahashi, Yoshinori; Yoshimura, Masashi; Matsumura, Hiroyoshi; Murakami, Satoshi; Inoue, Tsuyoshi; Mori, Yusuke; Takano, Kazufumi

    2016-05-01

    We developed a new protein crystallization method that incorporates paper. A small piece of paper, such as facial tissue or KimWipes, was added to a drop of protein solution in the traditional sitting drop vapor diffusion technique, and protein crystals grew by incorporating paper. By this method, we achieved the growth of protein crystals with reducing osmotic shock. Because the technique is very simple and the materials are easy to obtain, this method will come into wide use for protein crystallization. In the future, it could be applied to nanoliter-scale crystallization screening on a paper sheet such as in inkjet printing.

  19. Poster contributions; Contributions par affiches

    Energy Technology Data Exchange (ETDEWEB)

    Allegraud, K.; Gatilova, I.; Guaitella, O.; Ionikh, Y.; Roepcke, J.; Rousseau, A.; Aranchuk, L.E.; Larour, J.; Asad, S.; Tendero, C.; Tixier, C.; Jaoul, C.; Tristant, P.; Boisse-Laporte, C.; Leprince, P.; Leniniven, C.; Assouar, M.B.; Jimenez Rioboo, R.J.; Aubert, X.; Rousseau, A.; Sadeghi, N.; Bekstein, A.; Benhenni, M.; Yousfi, M.; Bousquet, A.; Granier, A.; Cartry, G.; Calafat, M.; Escaich, D.; Raynaud, P.; Clergereaux, R.; Cardoso, R.P.; Belmonte, T.; Henrion, G.; Sadeghi, N.; Cavarroc, M.; Mikikian, M.; Tessier, Y.; Boufendi, I.; Celestin, S.; Guaitella, O.; Bourdon, A.; Rousseau, A.; Cernogora, G.; Szopa, C.; Cavarroc, M.; Boufendi, I.; Commaux, N.; Geraud, A.; Pegourie, B.; Clairet, F.; Gil, C.; Gros, G.; Gunn, J.; Joffrin, E.; Hertout, P.; Costin, C.; Choimet, J.B.; Minea, T.; Couedel, L.; Mikikian, M.; Tessier, Y.; Boufendi, I.; Samarian, A.A.; Cousin, R.; Larour, J.; Gouard, P.; Raymond, P.; Curley, G.A.; Booth, J.P.; Corr, C.S.; Foldes, T.; Guillon, J.; Czarny, O.; Huysmans, G.; Daniel, A.; Belmonte, T.; Poucques, L. de; Imbert, J.C.; Teule-Gay, L.; Boisse-Laporte, C.; Devaux, S.; Manfredi, G.; Dif-Pradalier, G.; Grandgirard, V.; Sarazin, Y.; Garbet, X.; Ghendrih, Ph.; Dong, B.; Bauchire, J.M.; Pouvesle, J.M.; Magnier, P.; Hong, D.; Duluard, C.; Tillocher, T.; Mekkakia Maaza, N.; Dussart, R.; Mellhaoui, X.; Lefaucheux, P.; Puech, M.; Ranson, P.; Faudot, E.; Heuraux, S.; Colas, L.; Fubiani, G.; Boilson, D.; Hemsworth, R.S.; Gatilova, L.; Allegraud, K.; Ionikh, Y.; Roepcke, J.; Cartry, G.; Rousseau, A.; Gauthier, J.C.; Fourment, C.; Schurtz, G.; Nicolai, Ph.; Peyrusse, O.; Feugeas, J.L

    2006-07-01

    This document gathers the poster contributions among which 11 are relevant for fusion plasmas or particle acceleration: 1) the spectral study of a micro plasma from an X-pinch explosion; 2) experiments with a plasma density greater than the Greenwald value via the injection of icicles in Tore-Supra; 3) Bezier's surfaces and finite elements method for non-linear MHD; 4) 2-dimensional simulation of the RF casings before the ICRF antennas in tokamaks; 5) negative ion sources for ITER; 6) experimental characterization of electron heat transport on the laser integration line; 7) comparison of fluctuation measurement methods of plasma density via reflectometry in mode-o and mode-x in Tore-Supra; 8) water-bag model applied to kinetics equations of magnetic fusion plasmas; 9) computerized simulation of electron acceleration in plasma waves generated in a capillary pipe through laser wakefield; 10) the slowing-down of an alpha particle in a strongly magnetized dense plasma; and 11) stochastic processes of particle trapping by a wave in a magnetized plasma. (A.C.)

  20. DISSERTATION AS QUALIFICATION PAPER

    Directory of Open Access Journals (Sweden)

    A. P. Nesenchuk

    2008-01-01

    Full Text Available The paper considers problems pertaining to methodology and structure for dissertation preparation. All the problems have been solved on the basis of the analysis of questionnaire complexes. The paper presents concrete examples taken from the dissertations that have passed expertise of the Highest Certifying Commission.

  1. Transportation: Topic Paper E.

    Science.gov (United States)

    National Council on the Handicapped, Washington, DC.

    As one of a series of topic papers assessing federal laws and programs affecting persons with disabilities, this paper reviews the issue of transportation services. In the area of urban mass transit, four relevant pieces of legislation and public transportation accessibility regulations are cited, and cost issues are explored. Paratransit systems,…

  2. CATV Technical Papers.

    Science.gov (United States)

    National Cable Television Association, Inc., Washington, DC.

    Complete technical papers of the 1977 National Cable Television Association Convention are included in this report. Twenty-two of 32 papers and two abstracts cover the topics of advanced cable television techniques, human reactions to television picture impairment, special displays and services, protection from theft of service, everyday…

  3. Crepe Paper Colorimetry.

    Science.gov (United States)

    Pringle, David L.; And Others

    1995-01-01

    Uses crepe paper for the introduction of spectrophotometric concepts. Dyes used in the manufacturing of the crepe paper dissolve rapidly in water to produce solutions of colors. The variety of colors provides spectra in the visible spectrum that allow students to grasp concepts of absorption and transmission. (AIM)

  4. Paper Highlight — Site

    Science.gov (United States)

    In a recent paper published in Cancer Cell, ICBP investigators at the University of Texas Health Science Center, want to provide the potential mechanistic explanation how the known 20q13 and 17q23 amplicons transcriptionally control gene expression through long-range chromatin proximity. This paper describes how different large sets of data can be integrated for finding new biological mechanisms.

  5. Wrinkling of wet paper

    Science.gov (United States)

    Kim, Ho-Young; Kim, Jungchul; Mahadevan, L.

    2011-11-01

    It is a mundane experience that paper stained with water wrinkles. It is because a wetted portion of paper, which swells due to the hygroexpansive nature of the cellulose fiber network, deforms out of its original plane. Here we quantify the dynamics of wrinkling of wet paper coupled to the capillary imbibition of water into paper using a combination of experiment and theory. While supplying water from a capillary tube that touches the center of a paper strip, we measure the spreading rate of the wet area, wait time for the out-of-plane buckling, and temporal growth of a wrinkling magnitude. Using a theoretical model assuming a linear increase of the strain and an exponential decay of the elastic modulus with the water concentration, we construct scaling laws to predict the simultaneous capillary imbibition and wrinkling rates. This work was supported by the Wyss Institute of Harvard University.

  6. Paper Punch Tape

    CERN Multimedia

    Physicists coded and recorded their programs through series of holes on punch paper tape or on punched cards. It was popular in the 1970s due to its high throughput speed and low cost, paper tape was one of the original data storage methods for computers. Information was encoded in the distinct pattern of holes punched in the paper; the paper itself was oiled to facilitate being run through the reading mechanism and to prevent tears due to brittleness. Though the paper was cheap, it had low storage capacity (only a few dozen kilobytes per roll) and the machinery involved in punching the holes was quite expensive. Higher capacity alternatives, such as magnetic tape, has get developped.

  7. ESCO White Paper

    Science.gov (United States)

    EPA developed this white paper to explore energy performance contracting with Energy Service Companies (ESCOs) and its potential to be a best practice for installing solar thermal water heating systems in the commercial and industrial sector.

  8. Link to paper

    Data.gov (United States)

    U.S. Environmental Protection Agency — Link to the paper. This dataset is associated with the following publication: Naile, J., A.W. Garrison, J. Avants, and J. Washington. Isomers/enantiomers of...

  9. Nanotechnology in paper electronics

    Science.gov (United States)

    Demming, Anna; Österbacka, Professor Ronald; Han, Jin-Woo, Dr

    2014-03-01

    The ability to put cutting edge technology on paper—not in words but in a working physical form—has been attracting an increasing number of researchers over the past decade. Paper has many advantages that make it attractive for flexible electronics: it is relatively environmentally benign; it is renewable; it can be recycled; it is light weight; production processes for paper are well advanced; and it is inexpensive. This special issue, with guest editors Ronald Österbacka from Åbo Akademi University in Finland and Jin-Woo Han from the NASA AMES Research Center, features some of the latest in paper electronics research, including developments towards applications in displays, sensing and alternative energy sources, as well as fundamental studies to further our understanding of how paper can be most effectively used in electronics. As Andrew Steckl and colleagues in the US point out, 'Cellulose-based paper substrates were implemented as an electronic substrate as early as 1969, with most advancement occurring in the past decade largely due to technology improvements in thin film deposition and organic materials' [1, 2]. They report a detailed comparison between paper, standard liquid crystal display rigid glass and flexible glass for hosting pentacene organic thin film transistors, and obtain promising results for future paper-based devices. As most meaningful electronic devices rely on transistors to function, transistors feature quite prominently in this special issue. Rodrigo Martins and colleagues in France and Portugal study the effect of fibre type, structure and dimension on paper-based transistors and reveal further insights into how paper properties affect device performance [3]. Qing Wan and colleagues in China bring the state of the art in transistor technology to paper substrates [4], fabricating indium-zinc-oxide (IZO)-based protonic/electronic hybrid thin film transistors on paper and showing that they can be used as artificial synapses. Like the

  10. Paper Gains and Losses

    Institute of Scientific and Technical Information of China (English)

    ADAMMINTER

    2004-01-01

    Wet piles of old cardboard are stacked on both sides of a loading platform, leaving just enough room for a truck to stop between them. Zhang Guanan, the stocky general manager of the Liudian General Paper Mill Factory, stands in the middle of the space. Behind him is the roar of a paper mill and a long flatbed truck leaving a warehouse loaded with twenty-eight giant rolls of carton board destined for a box

  11. Developing a paper presentation.

    Science.gov (United States)

    Pierce, L L; Gregg, M M

    1994-01-01

    The purpose of this article is to provide suggestions for developing and presenting papers at an educational conference or other professional meeting. The authors offer suggestions on how to write an abstract, deal with rejection or success, develop an outline, construct a lecture, select audiovisual materials, and use public-speaking skills. The practical strategies described in this article are intended to enable rehabilitation nurses and other readers to develop and/or enhance their paper presentations.

  12. Online Paper Review Analysis

    Directory of Open Access Journals (Sweden)

    Doaa Mohey El-Din

    2015-09-01

    Full Text Available Sentiment analysis or opinion mining is used to automate the detection of subjective information such as opinions, attitudes, emotions, and feelings. Hundreds of thousands care about scientific research and take a long time to select suitable papers for their research. Online reviews on papers are the essential source to help them. The reviews save reading time and save papers cost. This paper proposes a new technique to analyze online reviews. It is called sentiment analysis of online papers (SAOOP. SAOOP is a new technique used for enhancing bag-of-words model, improving the accuracy and performance. SAOOP is useful in increasing the understanding rate of review's sentences through higher language coverage cases. SAOOP introduces solutions for some sentiment analysis challenges and uses them to achieve higher accuracy. This paper also presents a measure of topic domain attributes, which provides a ranking of total judging on each text review for assessing and comparing results across different sentiment techniques for a given text review. Finally, showing the efficiency of the proposed approach by comparing the proposed technique with two sentiment analysis techniques. The comparison terms are based on measuring accuracy, performance and understanding rate of sentences.

  13. CALL FOR PAPERS: Quantum control

    Science.gov (United States)

    Mancini, Stefano; Wiseman, Howard M.; Man'ko, Vladimir I.

    2004-10-01

    Over the last few decades, the achievements of highly precise technologies for manipulating systems at quantum scales have paved the way for the development of quantum control. Moreover, the proliferation of results in quantum information suggest that control theory might profitably be re-examined from this perspective. Journal of Optics B: Quantum and Semiclassical Optics will publish a topical issue devoted to quantum control. The Guest Editors invite contributions from researchers working in any area related to quantum control. Topics to be covered include: • Quantum Hamiltonian dynamics and programming control • Quantum decoherence control • Open loop control • Closed loop (feedback) control • Quantum measurement theory • Quantum noise and filtering • Estimation and decision theory • Quantum error correction • Group representation in quantum control • Coherent control in quantum optics and lasers • Coherent control in cavity QED and atom optics • Coherent control in molecular dynamics The topical issue is scheduled for publication in November 2005 and the DEADLINE for submission of contributions is 28 February 2005. All contributions will be peer-reviewed in accordance with the normal refereeing procedures and standards of Journal of Optics B: Quantum and Semiclassical Optics. Submissions should preferably be in either standard LaTeX form or Microsoft Word. Advice on publishing your work in the journal may be found at www.iop.org/journals/authors/jopb. Enquiries regarding this topical issue may be addressed to the Publisher, Dr Claire Bedrock (claire.bedrock@iop.org). There are no page charges for publication. The corresponding author of each paper published will receive a complimentary copy of the topical issue. Contributions to the topical issue should preferably be submitted electronically at www.iop.org/journals/authors/jopb or by e-mail to jopb@iop.org. Authors unable to submit online or by e-mail may send hard copy contributions

  14. Gas Mitigation in Paper Production

    Science.gov (United States)

    Santos, AS; Bittencourt, C.

    2017-07-01

    The Brazilian paper industry has competitive advantages offered by the favorable climate, which favors an increase in the yield of forest restoration, and consequently, in the productive process. On the other hand, following the greenhouse gases (GHG), we can see our constantly changing sun, causing the solar storms, allowing their prevention or mitigating measures. The objective of this work is to contribute to the construction of the understanding necessary for the reduction of GHG emission from a preliminary analysis of the pulp and paper sector. As a secondary objective, the text preliminarily analyzes a company’s behavior against the backdrop of the Paris Accord, which strengthens the global response to the threat of climate change and strengthens the capacity of countries to deal with the impacts of such changes. The identification of best practices in the pulp and paper industry is understood, focusing on environmental sustainability, such as the adoption of reforestation, obtaining significant results. In the case of the paper industry, the management of public forests for sustainable production, within the structure of the Ministry of the Environment, establishes the promotion of public awareness about the importance of conservation, recovery and sustainable management of forest resources.

  15. Recycling Paper Recycling

    Directory of Open Access Journals (Sweden)

    Martin A. Hubbe

    2014-02-01

    Full Text Available What do you do after a product has served its function and is no longer needed? Ideally, you recycle it. What do you do if people have neglected or forgotten so much of what has been learned in recent years about paper recycling? Well, one of the things that someone can do is to write a book. Very little of the contents of such a book may be new. But the book itself can be highly valuable, representing a lot of effort to select and organized material that will be helpful for the current and upcoming generations of papermaking technologists. This editorial describes a new book by Dr. Pratima Bajpai entitled Recycling and Deinking of Recovered Paper. Readers who deal with the recycling of paper will probably want to have a copy of it on a handy shelf.

  16. Call for Papers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>Internet Law Review is a scholarly monographic series focused on the research of internet law.It is sponsored by School of Intellectual Property,Peking University,and Internet Law Center of Peking University,edited by Professor Zhang Ping,and published twice a year. We are now preparing for the forthcoming issue of the Review,Volume 13,and prospective authors with new ideas,comprehensive and sound research methods and theories,and great creativity,are invited to submit your articles.Also,we strongly welcome excellent papers with high practicality and supported by detailed examples,and critical review papers to

  17. iPhone paper

    Science.gov (United States)

    2016-12-01

    Could you write a scientific manuscript using just your iPhone? Well, when Christoph Bartneck at the University of Canterbury in New Zealand was invited to submit a paper to the International Conference on Atomic and Nuclear Physics, in Atlanta, Georgia, in November, he decided to do just that.

  18. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National

  19. Two three pages papers

    NARCIS (Netherlands)

    Apt, K.R.; Constable, R.L.; Silva, A.

    2012-01-01

    Dexter was my manager during the first 8 months or so of my one year stay at the IBM Research Center at Yorktown Heights in the mid eighties. Our interaction in terms of scientific output was very slim — it consisted of just a single paper, titled "Limits for automatic verification of finite-state c

  20. Working Paper No.1

    Science.gov (United States)

    Graff, Harvey J.; Street, Brian V.; Jones, Stan

    1998-01-01

    This document is a collection of three parts: two extended papers and one shorter commentary on the International Adult Literacy Survey (IALS). These originally appeared in "Literacy Across the Curriculum" in response to an invitation for comment to several prominent international researchers. The first of these entitled "The…

  1. Pencil and paper

    DEFF Research Database (Denmark)

    Wong, Bang; Kjærgaard, Rikke Schmidt

    2012-01-01

    Creating pictures is integral to scientific thinking. In the visualization process, putting pencil to paper is an essential act of inward reflec- tion and outward expression. It is a constructive activity that makes our thinking specific and explicit. Compared to other constructive approaches...

  2. A Position Paper.

    Science.gov (United States)

    Hixson, Richard A.

    This position paper covers possible problems of collective bargaining. (1) The two sides should not bring prejudgments of good or bad to the negotiating table. (2) Neither side should exaggerate its strength or minimize its weakness. (3) Neither side should confuse intransigence with firmness. (4) The composition of each team must be carefully…

  3. Paper relief architecture

    NARCIS (Netherlands)

    Latka, J.F.

    2014-01-01

    The article presents two contemporary projects of paper structures relief architecture designed and built by Shigeru Ban Architects and Voluntary Architect Network. Author of the article took part in design and construction process of one of the projects. The project of Yaan Nursery School, which wa

  4. Abstracts of Selected Papers

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    The present inflation is compound inflation influenced by internal and external factors. The paper brings forward three stages of supply changes of working-age population: 1) Not until 2010, the first stage can be described as a buyer's market of labor, i

  5. Regional Activities Division. Papers.

    Science.gov (United States)

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on library network activities in Canada, the Third World, Japan, Malaysia, Brazil, and Sweden which were presented at the 1982 International Federation of Library Associations (IFLA) conference include: (1) "Canada: A Voluntary and Flexible Network," a review by Guy Sylvestre of the political, social, and economic structures…

  6. Regional Activities Division. Papers.

    Science.gov (United States)

    International Federation of Library Associations, The Hague (Netherlands).

    Papers on library network activities in Canada, the Third World, Japan, Malaysia, Brazil, and Sweden which were presented at the 1982 International Federation of Library Associations (IFLA) conference include: (1) "Canada: A Voluntary and Flexible Network," a review by Guy Sylvestre of the political, social, and economic structures affecting…

  7. Extending Paper Chromatography Inquiry

    Science.gov (United States)

    Finson, Kevin

    2004-01-01

    One of the "good old" standard activities middle school students seem to enjoy is paper chromatography. The procedures and materials needed are relatively simple and the results can be colorful. All too often, the activity ends just after these colorful results are obtained, cutting short the potential it holds for some further inquiry. With some…

  8. Writing on wet paper

    Science.gov (United States)

    Fridrich, Jessica; Goljan, Miroslav; Lisonek, Petr; Soukal, David

    2005-03-01

    In this paper, we show that the communication channel known as writing in memory with defective cells is a relevant information-theoretical model for a specific case of passive warden steganography when the sender embeds a secret message into a subset C of the cover object X without sharing the selection channel C with the recipient. The set C could be arbitrary, determined by the sender from the cover object using a deterministic, pseudo-random, or a truly random process. We call this steganography "writing on wet paper" and realize it using low-density random linear codes with the encoding step based on the LT process. The importance of writing on wet paper for covert communication is discussed within the context of adaptive steganography and perturbed quantization steganography. Heuristic arguments supported by tests using blind steganalysis indicate that the wet paper steganography provides improved steganographic security for embedding in JPEG images and is less vulnerable to attacks when compared to existing methods with shared selection channels.

  9. How Much Academic Contribution Do Chinese Graduate Students’Theses Make:An Empirical Analysis of References in Papers Published on Key Journals in 2013%我国硕士、博士学位论文的学术贡献有多大?--基于2013年核心期刊论文参考文献的实证分析

    Institute of Scientific and Technical Information of China (English)

    王传毅; 吴笛; 王兴咏

    2015-01-01

    The citation of a thesis is a measure of its academic contribution.According to the cita-tion type,a thesis’academic contribution can be divided into three categories:direct contribution,indi-rect contribution and total contribution.An analysis of the references of around 420,000 papers pub-lished on key journals indicates that Chinese graduate students'theses made a low academic contribu-tion,with a direct contribution of 1.59%,indirect contribution of 0.09%,and total contribution of 1. 68%.The contribution of doctoral dissertations is twice that of masters theses.%学术论文的被引情况是其学术贡献大小的标志之一。按照被引的不同类型,学术论文的学术贡献可分为直接贡献、间接贡献和总贡献。对2013年中文核心期刊近42万篇学术论文参考文献的分析显示:我国硕士、博士学位论文的学术贡献很低,直接贡献为1.59%,间接贡献为0.09%,总贡献为1.68%。其中博士学位论文的学术贡献约为硕士学位论文的两倍。

  10. Contributions to sampling statistics

    CERN Document Server

    Conti, Pier; Ranalli, Maria

    2014-01-01

    This book contains a selection of the papers presented at the ITACOSM 2013 Conference, held in Milan in June 2013. ITACOSM is the bi-annual meeting of the Survey Sampling Group S2G of the Italian Statistical Society, intended as an international  forum of scientific discussion on the developments of theory and application of survey sampling methodologies and applications in human and natural sciences. The book gathers research papers carefully selected from both invited and contributed sessions of the conference. The whole book appears to be a relevant contribution to various key aspects of sampling methodology and techniques; it deals with some hot topics in sampling theory, such as calibration, quantile-regression and multiple frame surveys, and with innovative methodologies in important topics of both sampling theory and applications. Contributions cut across current sampling methodologies such as interval estimation for complex samples, randomized responses, bootstrap, weighting, modeling, imputati...

  11. Abstracts of Selected Papers

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    On the Social Solidarity of Organization An Empirical Analysis Li Hanlin Abstract: Based on the 2002 survey data, this paper tries to measure solidarity in organization. The operationalization for this measurement goes from two points of view. One is from the degree of cohesion and another one is from the degree of vulnerability. To observe and measure the degree of cohesion three subscales like social support, vertical integration and organizational identity have been used. To observe and measure the degree of vulnerability other three subscales like dissatisfaction, relative deprivation and anomie have been used. The paper tries to explore finally under which condition the organization behavior and behavior orientation could go to the similarity or make some difference. Key words: Organization Cohesion Vulnerability Organization Behavior

  12. Outstanding student papers

    Science.gov (United States)

    Five presentations in the Hydrology Section were named Outstanding Student Papers at AGU's Spring Meeting in Baltimore, Md.Gwynn R. Johnson was honored for her presentation of “Solvent Rushing of an LNAPL Contaminated Soil.” She received her bachelor's degree in May 1993 and is now completing her master's degree (under the guidance of M.D. Annable, P.S.C. Rao, and K. Hatfield) in the Department of Environmental Engineering Sciences at the University of Florida.

  13. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in

  14. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in mainland China that has an international readership in mind.

  15. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in Mainland China that has an international

  16. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in mainland

  17. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in mainland

  18. Despre inovare. Working paper

    Directory of Open Access Journals (Sweden)

    Marina Mihăilă

    2013-03-01

    Full Text Available Innovation is at the heart of social and economic development. Although an important sector that generates products and services of high social and economic importance, construction sector is considered to be an underachiever in terms of innovation. This working paper briefly explores the state of innovation within construction sector, considering European tendencies, theoretical and practical developments and challenges raised by particular characteristic of construction products. Some preliminary conclusions are underlined as the basis for further extensive research.

  19. Pencil and paper

    DEFF Research Database (Denmark)

    Wong, Bang; Kjærgaard, Rikke Schmidt

    2012-01-01

    Creating pictures is integral to scientific thinking. In the visualization process, putting pencil to paper is an essential act of inward reflec- tion and outward expression. It is a constructive activity that makes our thinking specific and explicit. Compared to other constructive approaches suc...... such as writing or verbal explanations, visual representa- tion places distinct demands on our reasoning skills by forcing us to contextualize our understanding spatially....

  20. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in Mainland China that has an international readership in mind.This journal is aimed to establish a platform for LIS students,educators,researchers and library practitioners all over the world to engage in

  1. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in mainland China that has an international readership in mind.This journal is aimed to establish a platform for LIS students,educators,researchers and library practitioners all over the world to engage in

  2. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in mainland China that has an international readership in mind.This journal is aimed to establish a platform for LIS students,educators,researchers and library practitioners all over the world to engage in

  3. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    <正>Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in mainland China that has an international readership in mind.This journal is aimed to establish a platform for LIS students,educators,researchers and library practitioners

  4. Working Paper 88

    OpenAIRE

    Stix, Helmut; Knell, Markus

    2004-01-01

    By analyzing almost 1000 money demand estimations this paper attempts to summarize the disperse findings of this literature. Using both descriptive statistics and meta-regressions we derive several stylized facts about the two most prominent determinants of money demand–income and interest rate elasticities. In particular, we show that the size and signs of average elasticities are systematically related to the choice of included variables (e.g., M1 or M3, short-run or long-run interest rat...

  5. Call for Papers

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    Chinese Nursing Research is a nursing academic journal,CN 14-1375/R,ISSN 2095-7718.Size A4,48 pages,quarterly publication,color printing,public offerings at home and abroad which is in charge of the First Hospital of Shanxi Medical University,sponsored by Chinese Nursing Association Shanxi Branch and Shanxi Medical Periodical Press.Chinese Nursing Research is an important platform of nursing academic exchange.The mission is to carry out related guidelines,policies and regulations of journals publication,to publish academic papers,review articles of nursing domain experts

  6. From Paper to PDA

    DEFF Research Database (Denmark)

    Kanstrup, Anne Marie; Stage, Jan

    2009-01-01

    Mobile devices with small screens and minimal facilities for interaction are increasingly being used in complex human activities for accessing and processing information, while the user is moving. This paper presents a case study of the design and evaluation of a mobile system, which involved...... transformation of complex text and tables to digital format on a PDA. The application domain was an emergency medical ward, and the user group was junior registrars. We designed a PDA-based system for accessing information, focusing on the ward instruction, implemented a prototype and evaluated it for usability...

  7. MANAGING ON PAPER

    Institute of Scientific and Technical Information of China (English)

    1994-01-01

    Introduction Spoken instructions are often surprisingly ineffective, especially when in a foreign language and across cultures. With any course, and particularly on ATT courses, there always seems to be a daunting amount of information for trainees to absorb. This paper will outline how Chongqing University attempted to address the procedures and problems of organising a teacher-training course by using what we, rather inaccurately, called "memos". Memos were written by the project team and given to each trainee. They borrowed the style of a newsletter, but in content they resembled, what are called in China, "open letters". They were printed about three times a semester, and usually contained five or six points of information. We intended them to be both informal and businesslike. The word ’memo’ seemed to embody all this so ’memos’ they became. In practice they were longer and more structured than the kind of memo you would leave on somebody’s desk. To illustrate this paper we use both excerpts from memos and statistics and quotations from trainees.

  8. Contributing to Functionality

    DEFF Research Database (Denmark)

    Törpel, Bettina

    2006-01-01

    advocated in this paper, emerges in the specific dynamic interplay of actors, objectives, structures, practices and means. In this view, functionality is the result of creating, harnessing and inhabiting computer supported joint action spaces. The successful creation and further development of a computer......The objective of this paper is the design of computer supported joint action spaces. It is argued against a view of functionality as residing in computer applications. In such a view the creation of functionality is equivalent to the creation of computer applications. Functionality, in the view...... supported joint action space comprises a whole range of appropriate design contributions. The approach is illustrated by the example of the creation of the computer supported joint action space "exchange network of voluntary union educators". As part of the effort a group of participants created...

  9. DUSEL Theory White Paper

    CERN Document Server

    Raby, S; Babu, K S; Baer, H; Balantekin, A B; Barger, V; Berezhiani, Z; De Gouvêa, A; Dermisek, R; Dolgov, A; Perez, P Fileviez; Gabadadze, G; Gal, A; Gondolo, P; Haxton, W; Kamyshkov, Yu A; Kayser, B; Kearns, E; Kopeliovich, B; Lande, K; Marfatia, D; Mohapatra, R N; Nath, P; Nomura, Y; Olive, K A; Pati, J; Profumo, S; Shrock, R; Tavartkiladze, Z; Whisnant, K; Wolfenstein, L

    2008-01-01

    The NSF has chosen the site for the Deep Underground Science and Engineering Laboratory (DUSEL) to be in Lead, South Dakota. In fact, the state of South Dakota has already stepped up to the plate and contributed its own funding for the proposed lab, see http://www.sanfordlaboratoryathomestake.org/index.html. The final decision by NSF for funding the Initial Suite of Experiments for DUSEL will be made early in 2009. At that time the NSF Science Board must make a decision. Of order 200 experimentalists have already expressed an interest in performing experiments at DUSEL. In order to assess the interest of the theoretical community, the Center for Cosmology and Astro-Particle Physics (CCAPP) at The Ohio State University (OSU) organized a 3-day DUSEL Theory Workshop in Columbus, Ohio from April 4 - 6, 2008. The workshop focused on the scientific case for six proposed experiments for DUSEL: long baseline neutrino oscillations, proton decay, dark matter, astrophysical neutrinos, neutrinoless double beta decay and ...

  10. Call for papers

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Chinese Journal of Library and Information Science invites submission of academic papers from library and information science practitioners,educators and researchers.This peer-reviewed academic journal in the subject field of Library and Information Science(LIS)is published quarterly under the aegis of the National Science Library,Chinese Academy of Sciences.The Journal is the first English-language academic journal in LIS ever published in mainland China that has an international readership in mind.This journal is aimed to establish a platform for LIS students,educators,researchers and library practitioners all over the world to engage in intellectual dialogue so as to upgrade continuously library practice around the world in general and that of China in particular.

  11. ILC Higgs White Paper

    CERN Document Server

    Asner, D.M.; Calancha, C.; Fujii, K.; Graf, N.; Haber, H.E.; Ishikawa, A.; Kanemura, S.; Kawada, S.; Kurata, M.; Miyamoto, A.; Neal, H.; Ono, H.; Potter, C.; Strube, J.; Suehara, T.; Tanabe, T.; Tian, J.; Tsumura, J.; Watanuki, S.; Weiglein, G.; Yagyu, K.; Yokoya, H.

    2013-01-01

    The ILC Higgs White Paper is a review of Higgs Boson theory and experiment at the International Linear Collider (ILC). Theory topics include the Standard Model Higgs, the two-Higgs doublet model, alternative approaches to electroweak symmetry breaking, and precision goals for Higgs boson experiments. Experimental topics include the measurement of the Higgs cross section times branching ratio for various Higgs decay modes at ILC center of mass energies of 250, 500, and 1000 GeV, and the extraction of Higgs couplings and the total Higgs width from these measurements. Luminosity scenarios based on the ILC TDR machine design are used throughout. The gamma-gamma collider option at the ILC is also discussed.

  12. Conical instabilities on paper

    Energy Technology Data Exchange (ETDEWEB)

    Guven, Jemal; Vazquez-Montejo, Pablo [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, Apdo. Postal 70-543, 04510 Mexico, D.F. (Mexico); Mueller, Martin Michael, E-mail: jemal@nucleares.unam.mx [Equipe BioPhysStat, ICPMB-FR CNRS 2843, Universite Paul Verlaine-Metz, 1, boulevard Arago, 57070 Metz (France)

    2012-01-13

    The stability of the fundamental defects of an unstretchable flat sheet is examined. This involves expanding the bending energy to second order in deformations about the defect. The modes of deformation occur as eigenstates of a fourth-order linear differential operator. Unstretchability places a global linear constraint on these modes. Conical defects with a surplus angle exhibit an infinite number of states. If this angle is below a critical value, these states possess an n-fold symmetry labeled by an integer, n Greater-Than-Or-Slanted-Equal-To 2. A nonlinear stability analysis shows that the twofold ground state is stable, whereas excited states possess 2(n - 2) unstable modes which come in even and odd pairs. (paper)

  13. Position paper on mesotherapy

    Directory of Open Access Journals (Sweden)

    Rashmi Sarkar

    2011-01-01

    Full Text Available Mesotherapy is a controversial cosmetic procedure which has received publicity among the lay people, in the internet and in the media. It refers to minimally invasive techniques which consist of the use of intra- or subcutaneous injections containing liquid mixture of compounds (pharmaceutical and homeopathic medications, plant extracts, vitamins and other ingredients to treat local medical and cosmetic conditions. This position paper has examined the available evidence and finds that acceptable scientific evidence for its effectiveness and safety is lacking. IADVL taskforce, therefore would like to state that the use of this technique remains controversial at present. Further research and well-designed controlled scientific studies are required to substantiate the claims of benefit of this mode of therapy.

  14. From Paper to Electron

    Science.gov (United States)

    Anderson, Kent R.

    2000-01-01

    The Internet represents a different type of technology for publishers of scientific, technical, and medical journals. It is not a technology that sustains current markets and creates new efficiencies but is, rather, a disruptive technology that could radically alter market forces, profit expectations, and business models. This paper is a translation and amplification of the research done in this area, applied to a large-circulation new science journal, Pediatrics. The findings suggest that the journal of the future will be electronic, have a less volatile cost structure, be supported more by services than by content, be less able to rely on subscription revenues, and abandon certain elements of current value networks. It also provides a possible framework for other publishers to use to evaluate their own journals relative to this disruptive technology. PMID:10833160

  15. Outstanding student papers

    Science.gov (United States)

    Eight presentations were named Outstanding Student Papers in the Atmospheric Sciences Section at the 1995 Fall Meeting.Steve Davis, who presented “Reversal Effects in Wideband dE/dt from Lightning Measured at Multiple Ground Stations,” is currently attending the University of Florida pursuing a Ph.D. in electrical engineering. He graduated with high honors in 1990 with his bachelor's degree in electrical engineering from the University of Florida. He received his master's degree in 1992 from the University of Florida. The research for his master's degree was in the area of photonics with applications to laser and waveguide structures. His current research with Ewen Thomson involves measuring radiation from lightning at multiple ground stations. From these measurements, he hopes to determine lightning parameters such as velocities and currents and apply these to new and existing models.

  16. ILC Higgs White Paper

    CERN Document Server

    Asner, D M; Calancha, C; Fujii, K; Graf, N; Haber, H E; Ishikawa, A; Kanemura, S; Kawada, S; Kurata, M; Miyamoto, A; Neal, H; Ono, H; Potter, C; Strube, J; Suehara, T; Tanabe, T; Tian, J; Tsumura, J; Watanuki, S; Weiglein, G; Yagyu, K; Yokoya, H

    2013-01-01

    The ILC Higgs White Paper is a review of Higgs Boson theory and experiment at the International Linear Collider (ILC). Theory topics include the Standard Model Higgs, the two-Higgs doublet model, alternative approaches to electroweak symmetry breaking, and precision goals for Higgs boson experiments. Experimental topics include the measurement of the Higgs cross section times branching ratio for various Higgs decay modes at ILC center of mass energies of 250, 500, and 1000 GeV, and the extraction of Higgs couplings and the total Higgs width from these measurements. Luminosity scenarios based on the ILC TDR machine design are used throughout. The gamma-gamma collider option at the ILC is also discussed.

  17. The Roles of Conference Papers in IS

    DEFF Research Database (Denmark)

    Lanamäki, Arto; Persson, John Stouby

    2016-01-01

    understanding of conference papers in IS and the role they play for the authoring researchers. We present the first analysis of the papers published during the first six years (2010-2015) in the Scandinavian Conference on Information Systems (SCIS). We conducted interviews with ten SCIS authors. Following...... a framework adopted from Åkerlind [1], we identified how SCIS papers have the roles of fulfilling requirements, establishing oneself, developing personally, enabling change, and other roles. This article contributes to the reflection literature on the IS field by applying a practice lens to understand...... the role of conference papers in research....

  18. 40 CFR 247.10 - Paper and paper products.

    Science.gov (United States)

    2010-07-01

    ... 40 Protection of Environment 24 2010-07-01 2010-07-01 false Paper and paper products. 247.10... COMPREHENSIVE PROCUREMENT GUIDELINE FOR PRODUCTS CONTAINING RECOVERED MATERIALS Item Designations § 247.10 Paper and paper products. Paper and paper products, excluding building and construction paper grades. ...

  19. Uncapacitated facility location problems: contributions

    Directory of Open Access Journals (Sweden)

    Galvão Roberto Diéguez

    2004-01-01

    Full Text Available The objective of the present paper is to review my personal contributions in the field of uncapacitated facility location problems. These contributions took place throughout my academic career, from the time I was a Ph.D. student at Imperial College to the present day. They cover approximately 30 years, from 1973 to 2003; they address: algorithms developed for the p-median problem and for a general formulation of uncapacitated location problems; the study of dynamic location models; covering and hierarchical location problems; queuing-based probabilistic location models. The contributions encompass theoretical developments, computational algorithms and practical applications. All work took place in an academic environment, with the invaluable collaboration of colleagues (both in Brazil and abroad and research students at COPPE. Each section in the paper is dedicated to a topic that involves a personal contribution. Every one of them is placed within the context of the existing literature.

  20. Outstanding student paper awards

    Science.gov (United States)

    The Hydrology Section presented five outstanding student paper awards at the 1999 Spring Meeting in Boston, Massachusetts, last June.Maneesha Joshi presented a poster titled “Estimation of the Extent and Duration of Melt on the Greenland Ice Sheet using an Edge Detection Technique on Passive Microwave Data.” She received her B.Tech. in civil engineering from the Indian Institute of Technology, Bombay in 1991, and a M.S. in environmental engineering from State University of New York, Buffalo in 1994. Maneesha expects to complete her Ph.D. in civil engineering (remote sensing) in September 1999, under the supervision of Carolyn Merry (Department of Civil and Environmental Engineering & Geodetic Science), Ken Jezek, and John Bolzan (Byrd Polar Research Center) at the Ohio State University, Columbus, Ohio. Her thesis focuses on estimating the extent of melt, melt season, and duration, and absorbed radiation on the Greenland ice sheet from passive microwave and SAR data. Maneesha's other interests include image processing, issues related to global climate change, and photogrammetry.

  1. Outstanding student paper awards

    Science.gov (United States)

    The Atmospheric Sciences Section presented the following outstanding student paper awards at the AGU 1997 Fall Meeting in San Francisco, California, last December. James Corbett presented a poster on “Nitrogen and Sulfur Emissions From Oceangoing Ships.” James is a Ph.D. candidate in the Department of Engineering and Public Policy (EPP) at Carnegie Mellon University, Pittsburgh, Pa. He has been awarded a M.S. degree in EPP and recently completed the M.S. requirements in the Department of Mechanical Engineering. He graduated in 1985 with a degree in marine engineering technology from the California Maritime Academy and holds a California Professional Engineering License (Mechanical). He joined the doctoral program in engineering and public policy at Carnegie Mellon University in August 1995. In 1997, he was selected for a U.S. EPA STAR Fellowship. His research focuses on international maritime transportation and pollution issues, particularly air emissions from ship propulsion. James has developed the first global geographic characterization of air emissions from international maritime transport. As recently published in Science (Corbett and Fischbeck, 1997), his work estimates the global annual nitrogen and sulfur emissions from ships to be 3.08 terragrams (Tg) N and 4.24 Tg S, respectively.

  2. Classic papers in combinatorics

    CERN Document Server

    Rota, Gian-Carlo

    1987-01-01

    This volume surveys the development of combinatorics since 1930 by presenting in chronological order the fundamental results of the subject proved in over five decades of original papers by:.-T. van Aardenne-Ehrenfest.-R.L. Brooks.-N.G. de Bruijn.-G.F. Clements.-H.H. Crapo.-R.P. Dilworth.-J. Edmonds.-P.Erdös.-L.R. Ford, Jr.-D.R. Fulkerson.-D. Gale.-L. Geissinger.-I.J. Good.-R.L. Graham.-A.W. Hales.-P. Hall.-P.R. Halmos.-R.I. Jewett.-I. Kaplansky.-P.W. Kasteleyn.-G. Katona.-D.J. Kleitman.-K. Leeb.-B. Lindström.-L. Lovász.-D. Lubell.-C. St. J.A. Nash-Williams.-G. Pólya.-F.P. Ramsey.-G.C. Rota.-B.L. Rothschild.-H.J. Ryser.-C. Schensted.-M.P. Schützenberger.-R.P. Stanley.-G. Szekeres.-W.T. Tutte.-H.E. Vaughan.-H. Whitney.

  3. Darwin, Freud, Keynes et al.: Theory as Topic for Student Term Papers.

    Science.gov (United States)

    Dick, Florence; Dick, John R.

    1987-01-01

    Describes a research paper assignment which asks students to choose a significant contribution in any discipline, to detail what that contribution has been, to discover any controversy surrounding the contribution, and to assess the status of the contribution today. (MM)

  4. Internet access to scanned paper documents

    NARCIS (Netherlands)

    Worring, M.; Smeulders, A.W.M.; Witten, I.; Akscyn, R.; Shipman, F.M.

    1998-01-01

    In this contribution we identify the different structures to encounterin a hyperdocument. Methods are described for deriving those structures from scanned paper originals. The content and structure of the document is then made available in a form suited for an Internet browser. It provides convenien

  5. Feller's Contributions to Mathematical Biology

    OpenAIRE

    Baake, Ellen; Wakolbinger, Anton

    2015-01-01

    This is a review of William Feller's important contributions to mathematical biology. The seminal paper [Feller1951] "Diffusion processes in genetics" was particularly influential on the development of stochastic processes at the interface to evolutionary biology, and interesting ideas in this direction (including a first characterization of what is nowadays known as "Feller's branching diffusion") already shaped up in the paper [Feller 1939] (written in German) "The foundations of a probabis...

  6. Entropy Best Paper Award 2015

    Directory of Open Access Journals (Sweden)

    Kevin H. Knuth

    2015-02-01

    Full Text Available We are pleased to announce the “Entropy Best Paper Award” for 2015. Nominations were selected by the Editor-in-Chief and designated Editorial Board Members from all the papers published in 2011. Reviews and research papers were evaluated separately. We gladly announce that the following three papers have won the Entropy Best Paper Award in 2015:[...

  7. 公共关系定量研究中的理论贡献的方式对《PR Review》、《PR Research》中定量研究论文的内容分析%Methods of Theoretical Contribution of Quantitative Researches in Public Relations: A Content Analysis of Quantitative Papers in Public Relations Review and Journal of Public Relations Research

    Institute of Scientific and Technical Information of China (English)

    李贞芳; 陈先红; 江丛珍

    2012-01-01

    本研究从理论贡献的方式的角度,对《PR Review》、《PR Research》中采用社会科学定量研究方法的论文进行内容分析(N=214),发现在使用了某种理论或理论概念的161篇(75%)研究中,6%提供了概念的测量方案,12%检验了已有的理论或假设,30%提出了新的影响因素或适用范围,对关系理论,情景理论和卓越理论的验证和发展占主导地位。本文提供了一个公共关系定量研究中理论贡献方式的图谱,可成为公共关系定量研究理论创新的参照。%From the perspective of the methods of theoretical contribution, this paper analyses the quantitative papers (N= 214) in Public Relations Review and Journal of Public Relations Research with content analysis. It finds that among 161 theory-oriented articles, 6% provides the measurement of concept, 12% tests the existing theories or hypotheses, and 30% proposes new factors or new applications of theories. This paper provides a map of the methods of theoretical contribution made by quantitative papers in public relations.

  8. Community energy management : foundation paper

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-07-01

    This paper examined the potential for community energy management (CEM) to contribute to the reduction of greenhouse gas emissions in Canada. CEM is the integration of energy considerations into municipal planning and management processes so that the benefits of such planning exceed the impacts of individual initiatives. The goals of CEM may be to reduce public sector expenditures, job creation and improving the quality of life. The main initiative is to create more livable communities with affordable housing in attractive environments that enhance accessibility to services and employment, preserve green space, reduce pollution and noise and create a safer urban landscape. CEM typically encompasses land use planning, transportation management, influencing design, and fostering efficient and environmentally benign energy supply and delivery systems. Two particular aspects of CEM were examined in detail. The first was the relationship between land use and energy use and the second was the potential for district energy systems in Canadian communities. District heating has proven to make a significant difference in the overall energy intensity of urban settlements. It is a long accepted technology in Europe where entire district energy systems replace the furnaces of individual buildings. The advantage of district energy systems is the wide variety of fuels and energy sources that can be used to fire the boilers. They can also achiever higher levels of efficiency. District energy can be designed to provide for domestic hot water heating needs for both residential and business purposes, and as such, waste heat from industrial activities or power production is sufficient. District energy systems can also burn municipal solid waste, methane from landfill sites and sewage gas. There are currently 160 district energy systems in operation in Canada. 64 refs., 8 tabs., 2 figs.

  9. Selected papers on classical analysis

    CERN Document Server

    Nomizu, Katsumi

    2001-01-01

    This volume contains papers that originally appeared in Japanese in the journal Sūgaku. Ordinarily the papers would appear in the AMS translation of that journal, but to expedite publication, the Society has chosen to publish them as a volume of selected papers. The papers here are in the general area of mathematical analysis as it pertains to free probability theory.

  10. Paper Analogies Enhance Biology Teaching.

    Science.gov (United States)

    Stencel, John E.

    1997-01-01

    Describes how to use paper analogies as models to illustrate various concepts in biology, human anatomy, and physiology classes. Models include biochemical paper models, protein papergrams, a paper model of early brain development, and a 3-D paper model of a eukaryotic cell. (AIM)

  11. Papers on the nuclear regulatory dilemma

    Energy Technology Data Exchange (ETDEWEB)

    Barkenbus, J.N.; Freeman, S.D.; Weinberg, A.M.

    1985-10-01

    The four papers contained in this report are titled: (1) From Prescriptive to Performance-Based Regulation of Nuclear Power; (2) Nuclear Regulatory Reform: A Technology-Forcing Approach; (3) Improving the Regulation of Nuclear Power; and (4) Science and Its Limits: The Regulators' Dilemma. These four papers investigate issues relating to the long-term regulation of nuclear energy. They were prepared as part of the Institute for Energy Analysis' project on Nuclear Regulation funded by a grant from the Mellon Foundation and a smaller grant by the MacArthur Foundation. Originally this work was to be supplemented by contributions from the Nuclear Regulatory Commission and from the Department of Energy. These contributions were not forthcoming, and as a result the scope of our investigations was more restricted than we had originally planned.

  12. Review Paper on Flooding Attack in MANET

    Directory of Open Access Journals (Sweden)

    Ruchita Meher,

    2014-01-01

    Full Text Available Mobile ad-hoc network (MANET is widely applicable in various areas like military services, civilian environments and emergency operations. The issues in MANET are broadcasting, clustering, mobility management, bandwidth management and power management. Broadcasting becomes an important issue in MANET for route information discovery. The different routing attacks in MANET are flooding, black hole, link spoofing and wormhole attack. In this paper we are representing works proposed by various author on flooding attack. Our contribution in this paper is that we have presented details comparison of various counter based schemes.

  13. Abstracts of Major Papers in This Issue

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    The Linguistic Studies by Hu Zhuanglin, by YANG Xinzhang, p. 12 Based on the papers collected from CNKI, this paper attempts to examine the linguistic inquiries Prof. Zhuanglin Hu have made and describe his major fields of research and generalize his contributions to the development of linguistics in China. Apart from rhetoric, language planning, language testing, contrastive studies in English and Chinese, and lexicography, CNKI shows that Hu's major fields of research can be categorized into six types, including systemic functional linguistics, general linguistics, semiotics, discourse analysis, stylistics, language education, hypertext,

  14. Evolution of the scientific paper

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, J.E.

    1992-09-01

    The first papers reporting original research results in technical periodicals and proceedings appeared in the late 17th century. Since that time, the typical scientific paper has evolved from a fairly simple document, accessible to a general audience, to a much more complex one, aimed at a specialized audience. The purpose of this article is to give an overview of what the first scientific papers were like and how they evolved to their present form and style. To facilitate this discussion, the scientific paper`s development has arbitrarily been divided into four stages: the origin and formative years of the scientific paper (1665-1765), emergence of scientific papers written for specialized publications (1765-1865), development of the modem scientific paper (1865-1965), and hyperspecialization and computerization of the modem scientific paper (1965-?).

  15. Introduction to the Paper Symposium

    Science.gov (United States)

    Carpenter, D. K.

    1996-05-01

    authors emphasize the importance of "global variables" of a system. By this term they mean that the pressure and temperature of the surroundings are the values that determine the thermodynamic properties of the system (even if there might be variations of the pressure within the system). From their point of view, the pressure "of" a system is the pressure exerted on it by the surrounding fluid with which it is in thermal and mechanical equilibrium, and is therefore the pressure that is appropriate to such expressions as G= U + pV - TS. They believe that this takes care of the possibility that regions within a system may have different pressures, or even have pressures that are undefined; all that is required is that the pressures within the system are functions of the external pressure (that of the surroundings). As one of their main convictions, Schomaker and Waser hold that if the surroundings of a system are kept at fixed temperature and pressure, then any process that is isothermostatic and isobarostatic (in their sense) will conform to the condition deltaG is less than or equal to 0 in a quite general sense, even in the special case of a system confined to a fixed volume by an ideally rigid container. Schomaker and Waser have given considerable attention to the thermodynamic properties of systems that are exposed simultaneously to different pressures, such as is the case for the walls of a container for which the inner and outer pressures differ. To deal with this they applied elasticity theory to irregularly shaped solids. Although I requested that the details of such calculations be omitted from their manuscript, they did introduce the notion that the container walls may contribute significantly to the overall change in the Gibbs function. Although it is not a subject of controversy between the authors of the other papers, Schomaker and Waser also emphasize a distinction between the changes in the values of the energy, entropy, etc. and the changes in the

  16. Ergonomics Contribution in Maintainability

    Science.gov (United States)

    Teymourian, Kiumars; Seneviratne, Dammika; Galar, Diego

    2017-09-01

    The objective of this paper is to describe an ergonomics contribution in maintainability. The economical designs, inputs and training helps to increase the maintainability indicators for industrial devices. This analysis can be helpful, among other cases, to compare systems, to achieve a better design regarding maintainability requirements, to improve this maintainability under specific industrial environment and to foresee maintainability problems due to eventual changes in a device operation conditions. With this purpose, this work first introduces the notion of ergonomics and human factors, maintainability and the implementation of assessment of human postures, including some important postures to perform maintenance activities. A simulation approach is used to identify the critical posture of the maintenance personnel and implements the defined postures with minimal loads on the personnel who use the equipment in a practical scenario. The simulation inputs are given to the designers to improve the workplace/equipment in order to high level of maintainability. Finally, the work concludes summarizing the more significant aspects and suggesting future research.

  17. Evolution of the scientific paper

    Energy Technology Data Exchange (ETDEWEB)

    Harmon, J.E.

    1992-01-01

    The first papers reporting original research results in technical periodicals and proceedings appeared in the late 17th century. Since that time, the typical scientific paper has evolved from a fairly simple document, accessible to a general audience, to a much more complex one, aimed at a specialized audience. The purpose of this article is to give an overview of what the first scientific papers were like and how they evolved to their present form and style. To facilitate this discussion, the scientific paper's development has arbitrarily been divided into four stages: the origin and formative years of the scientific paper (1665-1765), emergence of scientific papers written for specialized publications (1765-1865), development of the modem scientific paper (1865-1965), and hyperspecialization and computerization of the modem scientific paper (1965- ).

  18. Recycling of Paper and Cardboard

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Damgaard, Anders

    2011-01-01

    Paper and cardboard are produced from pulp derived from plant fibers, primarily wood. Paper and cardboard is used for many different products, such as for packaging material, newsprint and advertisements. Most of these products have very short lifetimes and thus constitute a major fraction of most...... waste. Recycling of paper and cardboard production waste and postconsumer waste has a long history in the pulp and paper industry. The recycled material now makes up more than half of the raw material used in European pulp and paper industry (ERPC, 2004). This chapter describes briefly how paper...... and cardboard are produced and how waste paper is recycled in the industry. Quality requirements and use of recycled products are discussed, as are the resource and environmental issues of paper recycling....

  19. Recycling of Paper and Cardboard

    DEFF Research Database (Denmark)

    Christensen, Thomas Højlund; Damgaard, Anders

    2011-01-01

    waste. Recycling of paper and cardboard production waste and postconsumer waste has a long history in the pulp and paper industry. The recycled material now makes up more than half of the raw material used in European pulp and paper industry (ERPC, 2004). This chapter describes briefly how paper...... and cardboard are produced and how waste paper is recycled in the industry. Quality requirements and use of recycled products are discussed, as are the resource and environmental issues of paper recycling.......Paper and cardboard are produced from pulp derived from plant fibers, primarily wood. Paper and cardboard is used for many different products, such as for packaging material, newsprint and advertisements. Most of these products have very short lifetimes and thus constitute a major fraction of most...

  20. Business Plan: Paper Recycling Plant

    OpenAIRE

    Ali, Muhammad; Askari, Sana; Salman, Muhammad; Askari, Sheba

    2008-01-01

    This Business Plan was written for Business Plan competition organized by Ministry of Youth Affairs Government of Pakistan. It explains the paper recycling business, its pros and cons, cost of paper recycling, plant options and feasibility.

  1. Polymers Best Paper Award 2015

    Directory of Open Access Journals (Sweden)

    Alexander Böker

    2015-01-01

    Full Text Available Polymers is instituting an annual award to recognize the outstanding papers in the area of polymer science published in Polymers. We are pleased to announce the second “Polymers Best Paper Award” for 2015 [1]. Nominations were selected by the Editor-in-Chief and Editorial Board members of Polymers from all papers published in 2011. The awards are issued to reviews and articles respectively. We are pleased to announce that the following five papers were chosen:[...

  2. Entropy Best Paper Award 2014

    Directory of Open Access Journals (Sweden)

    Kevin H. Knuth

    2014-01-01

    Full Text Available In 2013, Entropy instituted the “Best Paper” award to recognize outstanding papers in the area of entropy and information studies published in Entropy [1]. We are pleased to announce the “Entropy Best Paper Award” for 2014. Nominations were selected by the Editor-in-Chief and designated Editorial Board Members from all the papers published in 2010.

  3. Molecules Best Paper Award 2013.

    Science.gov (United States)

    McPhee, Derek J

    2013-02-05

    Molecules has started to institute a "Best Paper" award to recognize the most outstanding papers in the area of natural products, medicinal chemistry and molecular diversity published in Molecules. We are pleased to announce the second "Molecules Best Paper Award" for 2013.

  4. Entropy Best Paper Award 2013

    Directory of Open Access Journals (Sweden)

    Kevin H. Knuth

    2013-02-01

    Full Text Available The journal Entropy is initiating a “Best Paper” award to recognize outstanding papers in the area of entropy and information studies published in Entropy. We are pleased to announce the first “Entropy Best Paper Award” for 2013. Nominations were selected by the Editor-in-Chief and selected Editorial Board Members from all the papers published in 2009 and evaluated by the Entropy Best Paper Award Committee. Reviews and articles were evaluated separately. A first prize is awarded to the selected review paper, and a first and second prize is awarded to the top two selected research articles.

  5. An unusual case of xylophagia (paper-eating

    Directory of Open Access Journals (Sweden)

    Mahesh Gowda

    2014-01-01

    Full Text Available Xylophagia is a condition involving the consumption of paper and form of eating disorder known as pica. Pica is an unusual craving for ingestion of either edible or inedible substances. Inhalants are volatile substances, which produce chemical vapors that can be inhaled to induce a psycho-active or mind altering effect. Although, pica is not linked to solvent abuse, here we report an adolescent case of paper-eating with solvent dependence.

  6. On Constructing Seminal Paper Genealogy.

    Science.gov (United States)

    Bae, Duck-Ho; Hwang, Se-Mi; Kim, Sang-Wook; Faloutsos, Christos

    2014-01-01

    Let us consider that someone is starting a research on a topic that is unfamiliar to them. Which seminal papers have influenced the topic the most? What is the genealogy of the seminal papers in this topic? These are the questions that they can raise, which we try to answer in this paper. First, we propose an algorithm that finds a set of seminal papers on a given topic. We also address the performance and scalability issues of this sophisticated algorithm. Next, we discuss the measures to decide how much a paper is influenced by another paper. Then, we propose an algorithm that constructs a genealogy of the seminal papers by using the influence measure and citation information. Finally, through extensive experiments with a large volume of a real-world academic literature data, we show the effectiveness and efficiency of our approach.

  7. Asian-Pacific Papers. Occasional Papers Number 10.

    Science.gov (United States)

    McCarthy, Brian, Ed.

    Sixteen papers are presented. Topics covered include language teaching, discourse analysis, code switching, phonetics, language and cultural identity, and descriptive and comparative studies. All presenters were from the Asia-Pacific area of the world. Papers include: "The Baba Malay Lexicon: Hokkien Loanwords in Baba Malay" (Anne…

  8. NIFS contributions to 19th IAEA fusion energy conference

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-11-01

    NIFS has presented 21 papers at the 19th IAEA Fusion Energy Conference (Lyon, France, 14-19 October 2002). The contributed papers are collected in this report. The 21 papers are indexed individually. (J.P.N.)

  9. Factors Contributing to Institutions Achieving Environmental Sustainability

    Science.gov (United States)

    James, Matthew; Card, Karen

    2012-01-01

    Purpose: The purpose of this paper is to determine what factors contributed to three universities achieving environmental sustainability. Design/methodology/approach: A case study methodology was used to determine how each factor contributed to the institutions' sustainability. Site visits, fieldwork, document reviews, and interviews with…

  10. Factors Contributing to Institutions Achieving Environmental Sustainability

    Science.gov (United States)

    James, Matthew; Card, Karen

    2012-01-01

    Purpose: The purpose of this paper is to determine what factors contributed to three universities achieving environmental sustainability. Design/methodology/approach: A case study methodology was used to determine how each factor contributed to the institutions' sustainability. Site visits, fieldwork, document reviews, and interviews with…

  11. Nineteen papers on algebraic semigroups

    CERN Document Server

    Aizenshtat, A Ya; Podran, N E; Ponizovskii, IS; Shain, BM

    1988-01-01

    This volume contains papers selected by leading specialists in algebraic semigroups in the U.S., the United Kingdom, and Australia. Many of the papers strongly influenced the development of algebraic semigroups, but most were virtually unavailable outside the U.S.S.R. Written by some of the most prominent Soviet researchers in the field, the papers have a particular emphasis on semigroups of transformations. Boris Schein of the University of Arkansas is the translator.

  12. Sensors Best Paper Award 2015

    Directory of Open Access Journals (Sweden)

    Vittorio M.N. Passaro

    2015-01-01

    Full Text Available Since 2011, an annual award system was instituted to recognize outstanding Sensors papers that are related to sensing technologies and applications and meet the aims, scope and high standards of this journal [1–4]. This year, the winners were chosen by the Section Editor-in-Chiefs of Sensors from among all the papers published in 2011 to track citations. Reviews and full research articles were considered separately. We gladly announce that the following eight papers were awarded the Sensors Best Paper Award in 2015.[...

  13. PaperBLAST: Text Mining Papers for Information about Homologs.

    Science.gov (United States)

    Price, Morgan N; Arkin, Adam P

    2017-01-01

    Large-scale genome sequencing has identified millions of protein-coding genes whose function is unknown. Many of these proteins are similar to characterized proteins from other organisms, but much of this information is missing from annotation databases and is hidden in the scientific literature. To make this information accessible, PaperBLAST uses EuropePMC to search the full text of scientific articles for references to genes. PaperBLAST also takes advantage of curated resources (Swiss-Prot, GeneRIF, and EcoCyc) that link protein sequences to scientific articles. PaperBLAST's database includes over 700,000 scientific articles that mention over 400,000 different proteins. Given a protein of interest, PaperBLAST quickly finds similar proteins that are discussed in the literature and presents snippets of text from relevant articles or from the curators. PaperBLAST is available at http://papers.genomics.lbl.gov/. IMPORTANCE With the recent explosion of genome sequencing data, there are now millions of uncharacterized proteins. If a scientist becomes interested in one of these proteins, it can be very difficult to find information as to its likely function. Often a protein whose sequence is similar, and which is likely to have a similar function, has been studied already, but this information is not available in any database. To help find articles about similar proteins, PaperBLAST searches the full text of scientific articles for protein identifiers or gene identifiers, and it links these articles to protein sequences. Then, given a protein of interest, it can quickly find similar proteins in its database by using standard software (BLAST), and it can show snippets of text from relevant papers. We hope that PaperBLAST will make it easier for biologists to predict proteins' functions.

  14. Some Contributions to Nonmonotonic Consequence

    Institute of Scientific and Technical Information of China (English)

    ZHU Zhaohui; ZHANG Dongmo; CHEN Shifu; ZHU Wujia

    2001-01-01

    This paper introduces a non-Horn rule WRM which is a weak form of rational monotony. We explore the effects of adding this non-Horn rule to the rules for the preferential inference. In this paper, a relation |~ is said to be P + WRM iff it is a preferential inference and satisfies the rule WRM. We establish the representation theorem for P+WRM, and compare the strength of WRM with some non-Horn rules appearing in literatures. Moreover, we explore the relation between P+WRM and conditional logic, and demonstrate that P+WRM is equivalent to ‘flat' fragment of conditional logic CS4.2. Another contribution of this paper is to explore the relation between two special kinds of preferential models, i.e., PRC model and quasi-linear model. Main result reveals that the latter is a special form of the former.

  15. End-of-waste criteria for waste paper: Technical proposals

    OpenAIRE

    VILLANUEVA KRZYZANIAK Alejandro; Eder, Peter

    2011-01-01

    This report presents proposals of end-of-waste (EoW) criteria for waste paper, defining the technical requirements that waste paper has to fulfil in order to cease to be waste in the EU. The report includes the background data and assessments used to support the proposals, including a comprehensive techno-economic analysis of waste paper recycling, and analyses of the potential economic, environmental and legal impacts when waste paper ceases to be waste. This report is a contribution to ...

  16. Summary of papers presented in the Theory and Modelling session

    OpenAIRE

    Lin-Liu Y.R.; Westerhof E.

    2012-01-01

    A total of 14 contributions were presented in the Theory and Modelling sessions at EC-17. One Theory and Modelling paper was included in the ITER ECRH and ECE sessions each. Three papers were in the area of nonlinear physics discussing parametric processes accompanying ECRH. Eight papers were based on the quasi-linear theory of wave heating and current drive. Three of these addressed the application of ECCD for NTM stabilization. Two papers considered scattering of EC waves by edge density fl...

  17. Working Paper on Social capital

    DEFF Research Database (Denmark)

    Lassen Hanan, Anne

    2013-01-01

    This paper outlines the major schools within social capital theory. Contemporary authors such as Coleman, Putnam and Bourdieu are elaborated on. The paper also presents a non-exhaustive review on studies of social capital. Furthermore, a criticial discussion on social capital is reviewed, before...

  18. Ten papers on complex analysis

    CERN Document Server

    Arakelyan, N U; Krushkal', S L; Gutlyanskii, V Ya; Kudyavin, V S

    1984-01-01

    The papers in this volume cover both one-variable and several-variable problems. An example of the former is a fifty-year-old classic on conformal mapping by M. A. Lavrent€´ev, while the latter is represented by a paper on the tangent complex of an analytic space by V. P. Palamodov.

  19. Seven papers in applied mathematics

    CERN Document Server

    Anosov, D V; Bogolyubov, N N; Bogoyavlenskii, O I; Bondarchuk, V S

    1985-01-01

    These papers in applied mathematics have been carefully selected by a joint committee of the AMS, the Association for Symbolic Logic (ASL), and the Institute of Mathematical Statistics (IMS) from publications not otherwise translated into English. The translated papers are carefully edited prior to publication.

  20. [Project Social Studies. Discipline Papers.

    Science.gov (United States)

    Minnesota Univ., Minneapolis. Project Social Studies Curriculum Center.

    The special papers provide a definition, delineate the scope, present a conceptual framework, and identify the method of inquiry and some techniques used for explaining the body of knowledge for each of six disciplines. The background papers to Project Social Studies are: 1) "Sociology" by Caroline Rose; 2) "The Study of Geography" by Fredrick R.…

  1. SQA specimen papers 2013, national 5, physics and model papers

    CERN Document Server

    SQA

    2013-01-01

    Practise for your exam on the official National 5 specimen paper from the Scottish Qualifications Authority . This book also includes additional model papers and extra revision guidance, making it an essential purchase for any student. - Discover how to get your best grade with answers checked by senior examiners. - Prepare for your exams with study skills guidance sections. - Gain vital extra marks and avoid common mistakes with examiner tips

  2. Selected papers in hydrologic sciences

    Science.gov (United States)

    A collection of short topical papers providing significant results of hydrologic studies by the U.S. Geological Survey, Department of the Interior, has been published as “Selected Papers in the Hydrologic Sciences, Volume 1” (Water-Supply Paper 2262). Edited by Eric L. Meyer, “Selected Papers in the Hydrologic Sciences“ is a new journal-type publication that will be a part of the existing U.S. Geological Survey Water-Supply Paper series. The “journal” is aimed at meeting the widespread public and professional interest of the hydrologic community in timely results from hydrologic studies derived from federal research programs, federal-state cooperative programs, and some work done on behalf of other federal agencies.This first volume, comprising eight papers, addresses a broad array of topics covering sediment chemistry, pesticides, toxic metals, and streamflow characteristics. Included are papers on a technique to measure oxygen in the root zone of saturated and unsaturated soils; measurement of surface runoff and collection of sediment samples from small areas; organic carbon in volcanic ash from Mount St. Helens, Washington; organochlorine pesticide and polychlorinated biphenyl in the Schuylkill River, Pennsylvania; interference of cadmium carbonate precipitation in the determination of cation exchange separation factors; confidence limtis for determining concentrations of tracer particles in sediment samples; determination of aquatic humic substances in natural water; and use of channel cross-section properties for estimating streamflow characteristics.

  3. Healthcare Engineering Defined: A White Paper.

    Science.gov (United States)

    Chyu, Ming-Chien; Austin, Tony; Calisir, Fethi; Chanjaplammootil, Samuel; Davis, Mark J; Favela, Jesus; Gan, Heng; Gefen, Amit; Haddas, Ram; Hahn-Goldberg, Shoshana; Hornero, Roberto; Huang, Yu-Li; Jensen, Øystein; Jiang, Zhongwei; Katsanis, J S; Lee, Jeong-A; Lewis, Gladius; Lovell, Nigel H; Luebbers, Heinz-Theo; Morales, George G; Matis, Timothy; Matthews, Judith T; Mazur, Lukasz; Ng, Eddie Yin-Kwee; Oommen, K J; Ormand, Kevin; Rohde, Tarald; Sánchez-Morillo, Daniel; Sanz-Calcedo, Justo García; Sawan, Mohamad; Shen, Chwan-Li; Shieh, Jiann-Shing; Su, Chao-Ton; Sun, Lilly; Sun, Mingui; Sun, Yi; Tewolde, Senay N; Williams, Eric A; Yan, Chongjun; Zhang, Jiajie; Zhang, Yuan-Ting

    2015-01-01

    Engineering has been playing an important role in serving and advancing healthcare. The term "Healthcare Engineering" has been used by professional societies, universities, scientific authors, and the healthcare industry for decades. However, the definition of "Healthcare Engineering" remains ambiguous. The purpose of this position paper is to present a definition of Healthcare Engineering as an academic discipline, an area of research, a field of specialty, and a profession. Healthcare Engineering is defined in terms of what it is, who performs it, where it is performed, and how it is performed, including its purpose, scope, topics, synergy, education/training, contributions, and prospects.

  4. Consensus Paper: Neuroimmune Mechanisms of Cerebellar Ataxias.

    Science.gov (United States)

    Mitoma, Hiroshi; Adhikari, Keya; Aeschlimann, Daniel; Chattopadhyay, Partha; Hadjivassiliou, Marios; Hampe, Christiane S; Honnorat, Jérôme; Joubert, Bastien; Kakei, Shinji; Lee, Jongho; Manto, Mario; Matsunaga, Akiko; Mizusawa, Hidehiro; Nanri, Kazunori; Shanmugarajah, Priya; Yoneda, Makoto; Yuki, Nobuhiro

    2016-04-01

    In the last few years, a lot of publications suggested that disabling cerebellar ataxias may develop through immune-mediated mechanisms. In this consensus paper, we discuss the clinical features of the main described immune-mediated cerebellar ataxias and address their presumed pathogenesis. Immune-mediated cerebellar ataxias include cerebellar ataxia associated with anti-GAD antibodies, the cerebellar type of Hashimoto's encephalopathy, primary autoimmune cerebellar ataxia, gluten ataxia, Miller Fisher syndrome, ataxia associated with systemic lupus erythematosus, and paraneoplastic cerebellar degeneration. Humoral mechanisms, cell-mediated immunity, inflammation, and vascular injuries contribute to the cerebellar deficits in immune-mediated cerebellar ataxias.

  5. Healthcare Engineering Defined: A White Paper

    Directory of Open Access Journals (Sweden)

    Ming-Chien Chyu

    2015-01-01

    Full Text Available Engineering has been playing an important role in serving and advancing healthcare. The term “Healthcare Engineering” has been used by professional societies, universities, scientific authors, and the healthcare industry for decades. However, the definition of “Healthcare Engineering” remains ambiguous. The purpose of this position paper is to present a definition of Healthcare Engineering as an academic discipline, an area of research, a field of specialty, and a profession. Healthcare Engineering is defined in terms of what it is, who performs it, where it is performed, and how it is performed, including its purpose, scope, topics, synergy, education/training, contributions, and prospects.

  6. Diffusive dynamics on paper matrix

    Science.gov (United States)

    Chaudhury, Kaustav; Kar, Shantimoy; Chakraborty, Suman

    2016-11-01

    Writing with ink on a paper and the rapid diagnostics of diseases using paper cartridge, despite their remarkable diversities from application perspective, both involve the motion of a liquid from a source on a porous hydrophilic substrate. Here we bring out a generalization in the pertinent dynamics by appealing to the concerned ensemble-averaged transport with reference to the underlying molecular picture. Our results reveal that notwithstanding the associated complexities and diversities, the resultant liquid transport characteristics on a paper matrix, in a wide variety of applications, resemble universal diffusive dynamics. Agreement with experimental results from diversified applications is generic and validates our unified theory.

  7. Quantum interaction. Revised selected papers

    Energy Technology Data Exchange (ETDEWEB)

    Song, Dawei; Zhang, Peng; Wang, Lei [Aberdeen Univ. (United Kingdom). School of Computing; Melucci, Massimo [Padua Univ., Padova (Italy). Dept. of Information Engineering; Frommholz, Ingo [Bedfordshire Univ. (United Kingdom); Arafat, Sachi (eds.) [Glasgow Univ. (United Kingdom). School of Computing Science

    2011-07-01

    This book constitutes the thoroughly refereed post-conference proceedings of the 5th International Symposium on Quantum Interaction, QI 2011, held in Aberdeen, UK, in June 2011. The 26 revised full papers and 6 revised poster papers, presented together with 1 tutorial and 1 invited talk were carefully reviewed and selected from numerous submissions during two rounds of reviewing and improvement. The papers show the cross-disciplinary nature of quantum interaction covering topics such as computation, cognition, mechanics, social interaction, semantic space and information representation and retrieval. (orig.)

  8. "Paper Cut Lady" Ku Shulan

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    WHEN the people in Xunyi County of Shaanxi Province talk about the traditional paper cut, they always speak of a "paper cut lady" Ku Shulan. Her works have been shown at the Xi’an Artists’ Gallery, Beijing China Art Gallery and Exhibition Hall of Central Academy of Fine Arts. Almost seventy years old, Ku Shulan is an ordinary country lady, and her artistic achievements were closely linked with her mother countryside. The traditional paper cut created and developed in Xunyi County, has a simple and bold style of Northern Shaanxi, and an exquisitely

  9. Another Day, Another White Paper

    Science.gov (United States)

    Tomlinson, Sally

    2006-01-01

    This article argues that the proposals in the 2005 White Paper can be largely explained by a New Labour emphasis on "meritocracy" merging with a right-wing belief in education as a means of creating an hierarchical society.

  10. Writing a clinical research paper

    Directory of Open Access Journals (Sweden)

    Ajao Oluwole

    1999-01-01

    Full Text Available A well-known unwritten law in institutions of higher learning is that of "Publish or perish". The duties of a University teacher, in order of priority are teaching, research and service. Reasons for writing clinical research papers are to get promoted, to get research grants and to make known, one′s findings in order to improve patients′ care. Writing papers is also a means of delivering continuous education, therefore publication is essential for any one pursuing an academic career. Research papers can be in the form of case reports, retrospective studies, prospective studies and laboratory or animal research. Two popular formats of writing papers are: The Vancouver Style and the Harvard System.

  11. All-printed paper memory

    KAUST Repository

    He, Jr-Hau

    2016-08-11

    All-printed paper-based substrate memory devices are described. In an embodiment, a paper-based memory device is prepared by coating one or more areas of a paper substrate with a conductor material such as a carbon paste, to form a first electrode of a memory, depositing a layer of insulator material, such as titanium dioxide, over one or more areas of the conductor material, and depositing a layer of metal over one or more areas of the insulator material to form a second electrode of the memory. In an embodiment, the device can further include diodes printed between the insulator material and the second electrode, and the first electrode and the second electrodes can be formed as a crossbar structure to provide a WORM memory. The various layers and the diodes can be printed onto the paper substrate by, for example, an ink jet printer.

  12. Genealogical Trees of Scientific Papers.

    Science.gov (United States)

    Waumans, Michaël Charles; Bersini, Hugues

    2016-01-01

    Many results have been obtained when studying scientific papers citations databases in a network perspective. Articles can be ranked according to their current in-degree and their future popularity or citation counts can even be predicted. The dynamical properties of such networks and the observation of the time evolution of their nodes started more recently. This work adopts an evolutionary perspective and proposes an original algorithm for the construction of genealogical trees of scientific papers on the basis of their citation count evolution in time. The fitness of a paper now amounts to its in-degree growing trend and a "dying" paper will suddenly see this trend declining in time. It will give birth and be taken over by some of its most prevalent citing "offspring". Practically, this might be used to trace the successive published milestones of a research field.

  13. Genealogical Trees of Scientific Papers.

    Directory of Open Access Journals (Sweden)

    Michaël Charles Waumans

    Full Text Available Many results have been obtained when studying scientific papers citations databases in a network perspective. Articles can be ranked according to their current in-degree and their future popularity or citation counts can even be predicted. The dynamical properties of such networks and the observation of the time evolution of their nodes started more recently. This work adopts an evolutionary perspective and proposes an original algorithm for the construction of genealogical trees of scientific papers on the basis of their citation count evolution in time. The fitness of a paper now amounts to its in-degree growing trend and a "dying" paper will suddenly see this trend declining in time. It will give birth and be taken over by some of its most prevalent citing "offspring". Practically, this might be used to trace the successive published milestones of a research field.

  14. Sensors Best Paper Award 2014

    Directory of Open Access Journals (Sweden)

    Vittorio M. N. Passaro

    2014-01-01

    Full Text Available In 2011, an annual award system was instituted to recognize outstanding Sensors papers that are related to sensing technologies and applications and meet the aims, scope and high standards of this journal [1–3]. This year, nominations were made by the Section Editor-in-Chiefs of Sensors from among all the papers published in 2010 to track citations. Reviews and full research articles were considered separately.

  15. Position Paper on Intelligent Supply Chains

    DEFF Research Database (Denmark)

    Møller, Charles

    This paper is intended to present and to analyze the concept of the Intelligent Supply Chain (ISC). The purpose of the paper is to: 1) Clarify the concept of the intelligent supply chain; 2) Identify emerging research opportunities; and 3) Specify a research engagement model for further exploration...... the concept of Intelligent Supply Chain and to establish an overall perspective based on information management. The claim made here is that the notion of the intelligent enterprise contributes with a new perspective on supply chain management that addresses the current challenges in an industrial supply...... chain. The argument is further that the existing information systems embodied in the standard enterprise information systems (EIS) have an important role in driving the development of modern supply chains though business processes. This is warranted by an analysis of the role of EIS on the development...

  16. A student's guide to Einstein's major papers

    CERN Document Server

    Kennedy, Robert E

    2012-01-01

    Our understanding of the physical universe underwent a revolution in the early twentieth century - evolving from the classical physics of Newton, Galileo, and Maxwell to the modern physics of relativity and quantum mechanics. The dominant figure in this revolutionary change was Albert Einstein. In a single year, 1905, Einstein produced breakthrough works in three areas of physics: on the size and the effects of atoms; on the quantization of the electromagnetic field; and on the special theory of relativity. In 1916 he produced a fourth breakthrough work, the general theory of relativity. A Student's Guide to Einstein's Major Papers focuses on Einstein's contributions, setting his major works into their historical context, and then takes the reader through the details of each paper, including the mathematics. This book helps the reader appreciate the simplicity and insightfulness of Einstein's ideas and how revolutionary his work was, and locate it in the evolution of scientific thought begun by the ancient...

  17. Intergenerational Practice: Contributing to a Conceptual Framework

    Science.gov (United States)

    Vieira, Sacha; Sousa, Liliana

    2016-01-01

    The ageing of the European population is creating a new demographic mix, increasing the relevance of intergenerational practice (IGP). To date, however, this field lacks an appropriate conceptual framework. This study aims to contribute to such a framework through an integrative review of peer-reviewed papers reporting on IGPs. Fifteen papers were…

  18. All-printed paper memory

    KAUST Repository

    Lien, Derhsien

    2014-08-26

    We report the memory device on paper by means of an all-printing approach. Using a sequence of inkjet and screen-printing techniques, a simple metal-insulator-metal device structure is fabricated on paper as a resistive random access memory with a potential to reach gigabyte capacities on an A4 paper. The printed-paper-based memory devices (PPMDs) exhibit reproducible switching endurance, reliable retention, tunable memory window, and the capability to operate under extreme bending conditions. In addition, the PBMD can be labeled on electronics or living objects for multifunctional, wearable, on-skin, and biocompatible applications. The disposability and the high-security data storage of the paper-based memory are also demonstrated to show the ease of data handling, which are not achievable for regular silicon-based electronic devices. We envision that the PPMDs manufactured by this cost-effective and time-efficient all-printing approach would be a key electronic component to fully activate a paper-based circuit and can be directly implemented in medical biosensors, multifunctional devices, and self-powered systems. © 2014 American Chemical Society.

  19. Papers in Phonology. Working Papers in Linguistics No. 41.

    Science.gov (United States)

    Hume, Elizabeth, Ed.

    Six working papers on phonology, primarily concerning less commonly taught languages, are presented are in this volume. Titles include: "Non-Uniqueness Condition and the Segmentation of the Chinese Syllable" (Benjamin Ao); "Theoretical Consequences of Metathesis in Maltese" (Elizabeth Hume); "Cs and Vs or Moras: The Case…

  20. Papers in Semantics. Working Papers in Linguistics No. 49.

    Science.gov (United States)

    Yoon, Jae-Hak, Ed.; Kathol, Andreas, Ed.

    1996-01-01

    Papers on semantic theory and research include: "Presupposition, Congruence, and Adverbs of Quantification" (Mike Calcagno); "A Unified Account of '(Ta)myen'-Conditionals in Korean" (Chan Chung); "Spanish 'imperfecto' and 'preterito': Truth Conditions and Aktionsart Effects in a Situation Semantics" (Alicia Cipria,…

  1. Contributions to industrial statistics

    OpenAIRE

    2015-01-01

    This thesis is about statistics' contributions to industry. It is an article compendium comprising four articles divided in two blocks: (i) two contributions for a water supply company, and (ii) significance of the effects in Design of Experiments. In the first block, great emphasis is placed on how the research design and statistics can be applied to various real problems that a water company raises and it aims to convince water management companies that statistics can be very useful to impr...

  2. The potential contribution of sinks to meeting Kyoto Protocol commitments

    DEFF Research Database (Denmark)

    Missfeldt, F.; Haites, E.

    2001-01-01

    The Kyoto Protocol to the climate convention makes provision for sink enhancement activities to contribute to meeting the greenhouse gas emissions limitation commitments of industrialised countries. This paper analyses the potential contribution of sink enhancement activities to meeting commitments...

  3. Active paper for active learning

    Directory of Open Access Journals (Sweden)

    Heather Brown

    1998-12-01

    Full Text Available Paper documents have great advantages in readability, portability and familiarity, but are necessarily static and slow to update. Much recent research has concentrated on the dynamic demonstrations, immediate feedback, and easy updating that can be provided by electronic teaching material. Although an increasing number of teaching packages make use of both paper and electronic documents, the two are typically accessed by completely separate interfaces. We have been taking a different approach and investigating the use of a DigitalDesk (Wellner, 1991; Wellner, 1993 as a means of integrating normal paper teaching material with electronic versions of the same material. Many printed books also exist in electronic form, and our goal is to allow these books to be used as natural interfaces to any additional information that may be present in the electronic version.

  4. Paper-based plasma sanitizers

    Science.gov (United States)

    Xie, Jingjin; Chen, Qiang; Suresh, Poornima; Roy, Subrata; White, James F.; Mazzeo, Aaron D.

    2017-05-01

    This work describes disposable plasma generators made from metallized paper. The fabricated plasma generators with layered and patterned sheets of paper provide a simple and flexible format for dielectric barrier discharge to create atmospheric plasma without an applied vacuum. The porosity of paper allows gas to permeate its bulk volume and fuel plasma, while plasma-induced forced convection cools the substrate. When electrically driven with oscillating peak-to-peak potentials of ±1 to ±10 kV, the paper-based devices produced both volume and surface plasmas capable of killing microbes. The plasma sanitizers deactivated greater than 99% of Saccharomyces cerevisiae and greater than 99.9% of Escherichia coli cells with 30 s of noncontact treatment. Characterization of plasma generated from the sanitizers revealed a detectable level of UV-C (1.9 nWṡcm-2ṡnm-1), modest surface temperature (60 °C with 60 s of activation), and a high level of ozone (13 ppm with 60 s of activation). These results deliver insights into the mechanisms and suitability of paper-based substrates for active antimicrobial sanitization with scalable, flexible sheets. In addition, this work shows how paper-based generators are conformable to curved surfaces, appropriate for kirigami-like “stretchy” structures, compatible with user interfaces, and suitable for sanitization of microbes aerosolized onto a surface. In general, these disposable plasma generators represent progress toward biodegradable devices based on flexible renewable materials, which may impact the future design of protective garments, skin-like sensors for robots or prosthetics, and user interfaces in contaminated environments.

  5. Selected papers on optomechanical design

    Science.gov (United States)

    O'Shea, Donald C.

    The papers included in this volume deal with a variety of topics in optical and optoelectronic science, engineering, and technology under the following headings: design, materials, tolerancing and specification, mounting, mechanical analysis, thermal analysis, stabilization, baffling, assembly and alignment, and scanning. Particular topics discussed include selection of materials and processes for metal optics, trends and limits in the production of optical elements and optical systems, aerospace mounts for down-to-earth optics, and thermal effects in optical systems. Papers are also presented on integrating Nd:YAG lasers into optical systems, line-of-sight steering and stabilization, and motors and control systems for rotating mirror deflectors.

  6. Selected papers from ESSDERC 2014

    Science.gov (United States)

    Bez, Roberto; Meneghesso, Gaudenzio; Pavan, Paolo; Zanoni, Enrico

    2015-11-01

    This special issue of Solid State Electronics includes 28 paper selected from the best presentations given at the 44th European Solid-State Device Research Conference (ESSDERC 2014, September 22-26, 2014 - Venice, Italy). These papers cover different topics in the research on solid-state devices. These topics are used also to organize the conference presentations in 7 tracks: Advanced CMOS: Devices, Process and Integration; Microwave, Opto and Power Solid-State Devices; Modeling and Simulation; Characterization, Reliability and Yield; Advanced and Emerging Memories; MEMS, NEMS, Bio-sensors and Display Technologies; Emerging non-CMOS Devices and Technologies.

  7. Street Papers, Work, and Begging

    DEFF Research Database (Denmark)

    Cockburn, Patrick Joseph

    2014-01-01

    Street papers are publications produced specifically for sale by the homeless and other vulnerable people in many countries around the world. Their social status is, however, often conspicuously unstable: ‘Get a job!’ has been reported as a common insult addressed to vendors, and street paper...... organisations have responded with their own rhetoric and strategies that aim at disrupting any analogy with begging. The present analysis frames these rhetorical confrontations as a struggle over economic legitimacy, highlighting some of the ways in which social actors build and sever the normatively...

  8. Deformable paper origami optoelectronic devices

    KAUST Repository

    He, Jr-Hau

    2017-01-19

    Deformable optoelectronic devices are provided, including photodetectors, photodiodes, and photovoltaic cells. The devices can be made on a variety of paper substrates, and can include a plurality of fold segments in the paper substrate creating a deformable pattern. Thin electrode layers and semiconductor nanowire layers can be attached to the substrate, creating the optoelectronic device. The devices can be highly deformable, e.g. capable of undergoing strains of 500% or more, bending angles of 25° or more, and/or twist angles of 270° or more. Methods of making the deformable optoelectronic devices and methods of using, e.g. as a photodetector, are also provided.

  9. Methane from waste containing paper

    Energy Technology Data Exchange (ETDEWEB)

    1981-12-24

    Waste solids containing paper are biologically treated in a system by: fermentation with lactobacilli, separation of the solids, ion exchange of the supernatant from the separation, anaerobic digestion of the ion-exchanged liquor, separation of a liquor from the fermentation, and digestion of the liquor. Thus, a municipal waste containing paper and water was inoculated with Aspergillus niger and lactobacilli for 2 days; the mixture was anaerobically treated and centrifuged; the clear liquor was ion exchanged; and the solid waste was filter pressed. The filter cake was treated with Trichoderma nigricaus and filtered. The filtrate and the ion-exchanged liquor were digested for CH/sub 4/ production.

  10. Paper mechanisms for sonic interaction

    DEFF Research Database (Denmark)

    Delle Monache, Stefano; Rocchesso, Davide; Qi, Ji

    2012-01-01

    Introducing continuous sonic interaction in augmented pop-up books enhances the expressive and performative qualities of movables, making the whole narrative experience more engaging and personal. The SaMPL Spring School on Sounding Popables explored the specific topic of paper-driven sonic...

  11. Overview paper on nuclear power

    Energy Technology Data Exchange (ETDEWEB)

    Spiewak, I.; Cope, D.F.

    1980-09-01

    This paper was prepared as an input to ORNL's Strategic Planning Activity, ORNL National Energy Perspective (ONEP). It is intended to provide historical background on nuclear power, an analysis of the mission of nuclear power, a discussion of the issues, the technology choices, and the suggestion of a strategy for encouraging further growth of nuclear power.

  12. Educational Choice. A Background Paper.

    Science.gov (United States)

    Quality Education for Minorities Network, Washington, DC.

    This paper addresses school choice, one proposal to address parental involvement concerns, focusing on historical background, definitions, rationale for advocating choice, implementation strategies, and implications for minorities and low-income families. In the past, transfer payment programs such as tuition tax credits and vouchers were…

  13. Getting rid of paper pushing.

    Science.gov (United States)

    Wyatt, C

    1994-04-01

    A hospital in Tacoma, Wash., is taking several steps toward streamlining its business office functions. For example, the hospital is transmitting 90% of its claims electronically and has automated the posting of remittance advice and the billing of Medicare secondary payers. "Eventually we'll have a paperless system; we won't push paper back and forth," the hospital's patient accounts manager says.

  14. Scientific papers: A new paradigm

    Science.gov (United States)

    Reid, George C.

    The problem of how to organize and write a scientific paper is a very basic one for most of us. A scientific paper is, after all, the only tangible product of a research scientist and, like all products, will be a failure if not marketed properly to reach its potential buyers. I think that a lack of attention to this “marketing and sales” aspect of research is a serious fault in our community, by which I mean those of us who publish in AGU journals.The potential audience for a scientific paper can be divided roughly into three distinct categories. The first group is usually rather small in number, consisting of fellow scientists working in a very closely related field, and to whom the details of the work are of major importance. The second group is also fellow scientists, but their interest is less sharply focused, and they are concerned with the broad outlines of the work and essential results. The third group is the sponsors and the people who actually pay for the work, whose interest in the details is minimal and they, sadly enough, are often concerned only with the fact that a paper has been published rather than its content.

  15. SUBMISSION OF PAPERS/POSTERS

    African Journals Online (AJOL)

    Serge Guiot

    2012-09-27

    Sep 27, 2012 ... up in sequencing batch mode, applying organic loading rates of 0.5 to 14 g ... reactor treating paper wastewater, and fed with brewery ... COD/l.d and then operated in continuous mode, with OLR ..... Influence of substrate feed.

  16. Fifteen papers on functional analysis

    CERN Document Server

    Allakhverdiev, B P; Fainshtein, A S; Khelemskii, AYa; Klenina, LI

    1984-01-01

    The papers in this volume cover topics on functional analysis. They have been selected, translated, and edited from publications not otherwise translated into English under the auspices of the AMS-ASL-IMS Committee on Translations from Russian and Other Foreign Languages.

  17. Eleven papers on differential equations

    CERN Document Server

    Akhmedov, S A; Berezanskii, Yu M; Bazalii, B V; Berezanskii, Yu M

    1985-01-01

    The papers in this volume, like those in the previous one, have been selected, translated, and edited from publications not otherwise translated into English under the auspices of the AMS-ASL-IMS Committee on Translations from Russian and Other Foreign Languages.

  18. Proceedings of the 1976 ISABELLE workshops. [Thirty papers

    Energy Technology Data Exchange (ETDEWEB)

    None

    1976-01-01

    Seven ISABELLE-sponsored workshops were held from May through August, 1976, each workshop dealing with a specific subject concerning the design of storage rings. Technical matters ranging from the confinement of high intensity beams of protons and antiprotons to the design of experimental apparatus were addressed. The summary papers for the workshops as well as a number of contributed papers are presented. A separate abstract was prepared for ERDA Energy Research Abstracts (ERA) for each of the thirty papers.

  19. Graphene-based antibacterial paper.

    Science.gov (United States)

    Hu, Wenbing; Peng, Cheng; Luo, Weijie; Lv, Min; Li, Xiaoming; Li, Di; Huang, Qing; Fan, Chunhai

    2010-07-27

    Graphene is a monolayer of tightly packed carbon atoms that possesses many interesting properties and has numerous exciting applications. In this work, we report the antibacterial activity of two water-dispersible graphene derivatives, graphene oxide (GO) and reduced graphene oxide (rGO) nanosheets. Such graphene-based nanomaterials can effectively inhibit the growth of E. coli bacteria while showing minimal cytotoxicity. We have also demonstrated that macroscopic freestanding GO and rGO paper can be conveniently fabricated from their suspension via simple vacuum filtration. Given the superior antibacterial effect of GO and the fact that GO can be mass-produced and easily processed to make freestanding and flexible paper with low cost, we expect this new carbon nanomaterial may find important environmental and clinical applications.

  20. Line Creep in Paper Peeling

    Directory of Open Access Journals (Sweden)

    Rosti J.

    2010-06-01

    Full Text Available We have studied experimentally the dynamics of the separation of a sheet of paper into two halves in a peeling configuration. The experimental setup consists of a peeling device, where a fracture front is driven along the plane of the paper, with a constant force. The theoretical picture is how an elastic line interacts with a random landscape of fracture toughness. We compare the results with theoretical simulations in several aspects. One recent finding concerns the autocorrelation function of the average front position. The data from the experiments produces so-called cusps or singularities in the correlation function, as predicted by the functional renormalization group theory for elastic lines. Comparisons with simulations with either a short range or a long range elastic kernel demonstrate that the latter agrees with the experimental observations, as expected.

  1. Paper mechanisms for sonic interaction

    DEFF Research Database (Denmark)

    Delle Monache, Stefano; Rocchesso, Davide; Qi, Ji

    2012-01-01

    Introducing continuous sonic interaction in augmented pop-up books enhances the expressive and performative qualities of movables, making the whole narrative experience more engaging and personal. The SaMPL Spring School on Sounding Popables explored the specific topic of paper-driven sonic narra...... narratives. Working groups produced several sketches of sonic interactions with movables. The most significant sketches of sounding popables are presented and analyzed.......Introducing continuous sonic interaction in augmented pop-up books enhances the expressive and performative qualities of movables, making the whole narrative experience more engaging and personal. The SaMPL Spring School on Sounding Popables explored the specific topic of paper-driven sonic...

  2. Paper Interfaces for Learning Geometry

    OpenAIRE

    Bonnard, Quentin; Verma, Himanshu; Kaplan, Frédéric; Dillenbourg, Pierre

    2012-01-01

    Paper interfaces offer tremendous possibilities for geometry education in primary schools. Existing computer interfaces designed to learn geometry do not consider the integration of conventional school tools, which form the part of the curriculum. Moreover, most of computer tools are designed specifically for individual learning, some propose group activities, but most disregard classroom-level learning, thus impeding their adoption. We present an augmented reality based tabletop system with ...

  3. Detection of landmines (Review Paper

    Directory of Open Access Journals (Sweden)

    A.K. Sinha

    2001-04-01

    Full Text Available Detection of landmines is a problem concerning both military and peacekeeping forces. This paper reviews literature on strategic minefield layouts, modern mine clearing, and mine countermeasure techniques based on mechanical methods. Discusses hydraulic and signal processing techniques, ion-trap mobility spectrometer, subsurface probing radar and few other novel methods employed for this purpose. The specialised directions that the landmine detection methods are taking are clearly pointed out.

  4. Construction-Paper Puzzle Masterpieces

    Science.gov (United States)

    Vance, Shelly

    2010-01-01

    Creating an appreciation of art history in her junior-high students has always been one of the author's greatest challenges as an art teacher. In this article, the author describes how her eighth-grade students re-created a famous work of art--piece by piece, like a puzzle or a stained-glass window--out of construction paper. (Contains 1 resource.)

  5. RESEARCH PAPER ON MULTILEVEL PARKING

    OpenAIRE

    Simran Karamchandani*, Sourabh Choudhary

    2016-01-01

    The internetworking of physical devices, vehicles buildings and other items—embedded with electronics, software, sensors, and network connectivity that enable these objects to collect and exchange data. The IoT allows objects to be sensed and controlled remotely across existing network infrastructure, creating opportunities for more direct integration of the physical world into computer-based systems, and resulting in improved efficiency. In this paper we are discussing the problems exist in ...

  6. Photoerasing paper and thermocoloring film

    Science.gov (United States)

    Kanakkanatt, Sebastian V.

    1997-08-01

    Thermal coloration of spiropyrans and spiroxazines at or above their melting point is well known to photochromists. The erasure of the color developed by exposure of photochromic paper by radiations of certain wavelengths in the visible region is little known. Six-nitrospirobenzopyran and 8- nitrospirobenzopyran, 8-methoxy-6-nitrospirobenzo-pyran, 6- methoxy-8-nitrospirobenzopyran, and 6,8-dinitrospirobenzopyran have been studied. The medium in which these photochromic dyes were dissolved or incorporated was limited to cellulose derivatives such as cellulose acetate, cellulose acetate- butyrate, and cellulose trinitrate. Paper coated with 6- nitrospirobenzopyran dissolved in an ethyl acetate solution of cellulose trinitrate readily colored on exposure to UV light or IR radiation and faded on exposure to light in the visible range. This unusual phenomenon, although not fully understood, is believed to be a selective light sensitizing ability of nitro groups. The applications of photoerasing paper and thermally colorable films are numerous, such as in polaroid type photography, in copy machines, and in thermally stable photochromic ophthalmic lenses.

  7. Geothermal hydrogen - a vision? Paper

    Energy Technology Data Exchange (ETDEWEB)

    Zittel, W.; Weindorf, W.; Wurster, R.; Bussmann, W.

    2001-07-01

    With the progresses in geothermal electricity production by means of the hot-dry-rock (HDR) method electricity might be produced at cost of between 0.07 - 0.09 ECU/kWh, depending on systems sizes of between 5 - 20 MW{sub e}. The electricity can be used to produce hydrogen from electrolysis and water. This method of electricity production offers high availability with operating hour of between 7,600 - 8,000 hours per year. The 40 GWh electricity production per year from one 5 MW{sub e} geothermal plant are sufficient to produce enough hydrogen for the operation of an average fueling station with about 400 refuelings per day at cost of about 20 - 30 percent higher than today's gasoline (including taxes). In this contribution some details of the analysis are presented as well as a general discussion of geothermal hydrogen production as a future energy vector. (orig.)

  8. School Contribution to Rural Communities: Leadership Issues. CRLRA Discussion Paper Series.

    Science.gov (United States)

    Johns, Susan; Kilpatrick, Sue; Falk, Ian; Mulford, Bill

    A case study exploring the relationship between local leadership and the school-community partnership was conducted in a small, isolated Australian mining town. Data were generated from written materials such as the local newspaper and interviews with 8 school staff members and 11 community members involved with the schools or representing…

  9. How sonochemistry contributes to green chemistry?

    Science.gov (United States)

    Chatel, Gregory

    2017-03-15

    Based on the analyses of papers from the literature, and especially those published in Ultrasonics Sonochemistry journal, the contribution of sonochemistry to green chemistry area has been discussed here. Important reminders and insights on the good practices and considerations have been made to understand and demonstrate how sonochemistry can continue to efficiently contribute to green chemistry area in the further studies. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Published papers on telepathology projects

    Directory of Open Access Journals (Sweden)

    Sadrieh Hajesmaeel-Gohari

    2015-10-01

    Full Text Available Introduction: Although many studies have been conducted in the telepathology field in recent years, a systematic review that examines studies in a comparative manner has not yet been undertaken. This paper aims to review the published papers on telepathology projects and compare them in several aspects such as telepathology method,telecommunication method, clinical outcome, etc. Method: This is a systematic review study. PubMed database was used to find the studies published in the past ten years (2004–2014. The 71 final related papers were evaluated. Data were extracted from these studies based on the following items: country, national (in country or international (between countries, frozen section or slide, body part, type of camera used, telecommunication method, telepathology method, clinical outcome, cost evaluation, satisfaction evaluation and the description of consultation providers and receivers. Data were analyzed using descriptive analysis. Results: Results showed that most of the studies were performed in developed countries on a national level, on slide and on a specific body part. In most studies, a Nikon camera was used to take images. Online methods were the most used telecommunication method in the studies, while store and forward was the most used telepathology method. Clinical outcome of many studies showed that telepathology is a reliable and accurate method for consultation. More than half of the studies considered the cost, and most of them showed that a telepathology system is cost effective. Few studies evaluated satisfaction of the participants. In most studies, the telepathology project was undertaken between pathologists. Conclusion: Although there is enough evidence to suggest that telepathology is an effective way of consultation between pathologists, there are still some areas that should be addressed and for which there is a lack of convincing evidence. For example, pathologist satisfaction, cost evaluation

  11. Westvaco Paper Mill - PSD Applicability

    Science.gov (United States)

    This document may be of assistance in applying the New Source Review (NSR) air permitting regulations including the Prevention of Significant Deterioration (PSD) requirements. This document is part of the NSR Policy and Guidance Database. Some documents in the database are a scanned or retyped version of a paper photocopy of the original. Although we have taken considerable effort to quality assure the documents, some may contain typographical errors. Contact the office that issued the document if you need a copy of the original.

  12. White Paper on Nuclear Astrophysics

    OpenAIRE

    Arcones, Almudena; Bardayan, Dan W.; Beers, Timothy C.; Berstein, Lee A.; Blackmon, Jeffrey C.; Messer, Bronson; Brown, B. Alex; Brown, Edward F; Brune, Carl R.; Champagne, Art E.; Chieffi, Alessandro; Couture, Aaron J.; Danielewicz, Pawel; Diehl, Roland; El-Eid, Mounib

    2016-01-01

    This white paper informs the nuclear astrophysics community and funding agencies about the scientific directions and priorities of the field and provides input from this community for the 2015 Nuclear Science Long Range Plan. It summarizes the outcome of the nuclear astrophysics town meeting that was held on August 21-23, 2014 in College Station at the campus of Texas A&M University in preparation of the NSAC Nuclear Science Long Range Plan. It also reflects the outcome of an earlier town mee...

  13. Relativity on Rotated Graph Paper

    CERN Document Server

    Salgado, Roberto B

    2011-01-01

    We present visual calculations in special relativity using spacetime diagrams drawn on graph paper that has been rotated by 45 degrees. The rotated lines represent lightlike directions in Minkowski spacetime, and the boxes in the grid (called "light-clock diamonds") represent units of measurement modeled on the ticks of an inertial observer's lightclock. We show that many quantitative results can be read off a spacetime diagram by counting boxes, using a minimal amount of algebra. We use the Doppler Effect, in the spirit of the Bondi k-calculus, to motivate the method.

  14. Summary of papers presented in the Theory and Modelling session

    Directory of Open Access Journals (Sweden)

    Lin-Liu Y.R.

    2012-09-01

    Full Text Available A total of 14 contributions were presented in the Theory and Modelling sessions at EC-17. One Theory and Modelling paper was included in the ITER ECRH and ECE sessions each. Three papers were in the area of nonlinear physics discussing parametric processes accompanying ECRH. Eight papers were based on the quasi-linear theory of wave heating and current drive. Three of these addressed the application of ECCD for NTM stabilization. Two papers considered scattering of EC waves by edge density fluctuations and related phenomena. In this summary, we briefly describe the highlights of these contributions. Finally, the three papers concerning modelling of various aspects of ECE are reported in the ECE session.

  15. Combinatorics Advances : Papers from a Conference

    CERN Document Server

    Mahmoodian, Ebadollah

    1995-01-01

    On March 28~31, 1994 (Farvardin 8~11, 1373 by Iranian calendar), the Twenty­ fifth Annual Iranian Mathematics Conference (AIMC25) was held at Sharif University of Technology in Tehran, Islamic Republic of Iran. Its sponsors in~ eluded the Iranian Mathematical Society, and the Department of Mathematical Sciences at Sharif University of Technology. Among the keynote speakers were Professor Dr. Andreas Dress and Professor Richard K. Guy. Their plenary lec~ tures on combinatorial themes were complemented by invited and contributed lectures in a Combinatorics Session. This book is a collection of refereed papers, submitted primarily by the participants after the conference. The topics covered are diverse, spanning a wide range of combinatorics and al~ lied areas in discrete mathematics. Perhaps the strength and variety of the pa~ pers here serve as the best indications that combinatorics is advancing quickly, and that the Iranian mathematics community contains very active contributors. We hope that you find the p...

  16. The Carbon Footprint of Conference Papers.

    Directory of Open Access Journals (Sweden)

    Diomidis Spinellis

    Full Text Available The action required to stem the environmental and social implications of climate change depends crucially on how humankind shapes technology, economy, lifestyle and policy. With transport CO2 emissions accounting for about a quarter of the total, we examine the contribution of CO2 output by scientific travel. Thankfully for the reputation of the scientific community, CO2 emissions associated with the trips required to present a paper at a scientific conference account for just 0.003% of the yearly total. However, with CO2 emissions for a single conference trip amounting to 7% of an average individual's total CO2 emissions, scientists should lead by example by demonstrating leadership in addressing the issue.

  17. The Blue Box White Paper

    CERN Document Server

    Tippett, Benjamin K

    2013-01-01

    This white paper is an explanation of Ben and Dave's TARDIS time machine, written for laypeople who are interested in time travel, but have no technical knowledge of Einstein's Theory of General Relativity. The first part of this paper is an introduction to the pertinent ideas from Einstein's theory of curved spacetime, followed by a review of other popular time machine spacetimes. We begin with an introduction to curvature and lightcones. We then explain the Alcubierre Warp Drive, the Morris-Thorne wormhole, and the Tipler cylinder. We then describe the Traversable Achronal Retrograde Domain in Spacetime (TARDIS), and explain some of its general properties. Our TARDIS is a bubble of spacetime curvature which travels along a closed loop in space and time. A person travelling within the bubble will feel a constant acceleration. A person outside of the TARDIS will see two bubbles: one which is evolving forwards in time, and one which is evolving backwards in time. We then discuss the physical limitations which ...

  18. White Paper on Nuclear Astrophysics

    CERN Document Server

    Arcones, Almudena; Beers, Timothy; Berstein, Lee; Blackmon, Jeff; Bronson, Messer; Brown, Alex; Brown, Edward; Brune, Carl; Champagne, Art; Chieffi, Alessandro; Couture, Aaron; Danielewicz, Pawel; Diehl, Roland; El-Eid, Mounib; Escher, Jutta; Fields, Brian; Frohlich, Carla; Herwig, Falk; Hix, William Raphael; Iliadis, Christian; Lynch, William; McLaughlin, Gail; Meyer, Bradley; Mezzacappa, Anthony; Nunes, Filomena; O'Shea, Brian; Prakash, Madappa; Pritychenko, Boris; Reddy, Sanjay; Rehm, Ernst; Rogachev, Grigory; Rutledge, Robert; Schatz, Hendrik; Smith, Michael; Stairs, Ingrid; Steiner, Andrew; Strohmayer, Tod; Timmes, Frank; Townsley, Dean; Wiescher, Michael; Zegers, Remco; Zingale, Michael

    2016-01-01

    This white paper informs the nuclear astrophysics community and funding agencies about the scientific directions and priorities of the field and provides input from this community for the 2015 Nuclear Science Long Range Plan. It summarizes the outcome of the nuclear astrophysics town meeting that was held on August 21-23, 2014 in College Station at the campus of Texas A&M University in preparation of the NSAC Nuclear Science Long Range Plan. It also reflects the outcome of an earlier town meeting of the nuclear astrophysics community organized by the Joint Institute for Nuclear Astrophysics (JINA) on October 9- 10, 2012 Detroit, Michigan, with the purpose of developing a vision for nuclear astrophysics in light of the recent NRC decadal surveys in nuclear physics (NP2010) and astronomy (ASTRO2010). The white paper is furthermore informed by the town meeting of the Association of Research at University Nuclear Accelerators (ARUNA) that took place at the University of Notre Dame on June 12-13, 2014. In summ...

  19. Collisions of planetesimals and formation of planets

    CERN Document Server

    Dvorak, Rudolf; Süli, Áron; Schäfer, Christoph M; Speith, Roland; Burger, Christoph

    2015-01-01

    We present preliminary results of terrestrial planet formation using on the one hand classical numerical integration of hundreds of small bodies on CPUs and on the other hand -- for comparison reasons -- the results of our GPU code with thousands of small bodies which then merge to larger ones. To be able to determine the outcome of collision events we use our smooth particle hydrodynamics (SPH) code which tracks how water is lost during such events.

  20. Collisions of Planetesimals and Formation of Planets

    Science.gov (United States)

    Dvorak, Rudolf; Maindl, Thomas I.; Süli, Áron; Schäfer, Christoph M.; Speith, Roland; Burger, Christoph

    2016-01-01

    We present preliminary results of models of terrestrial planet formation using on the one hand classical numerical integration of hundreds of small bodies on CPUs and on the other hand-for comparison-the results of our GPU code with thousands of small bodies which then merge to larger ones. To be able to determine the outcome of collision events we use our smooth particle hydrodynamics (SPH) code which tracks how water is lost during such events.

  1. Aggregates: The Fundamental Building Blocks of Planetesimals?

    Science.gov (United States)

    Cuzzi, J. N.; Hartlep, T.; Simon, J. I.; Cato, M. J.

    2017-01-01

    The initial accretion of primitive asteroids (meteorite parent bodies) from freely-floating nebula particles remains problematic. Traditional growth-by-sticking models in turbulent nebulae encounter a formidable "meter-size barrier" due to both drift and destruction, or even a mmtocmsize "bouncing" barrier. Even if growth by sticking could somehow breach these barriers (perhaps if the actual sticking or strength is larger than current estimates, which are based on pure ice or pure silicate), turbulent nebulae present further obstacles through the 1-10km size range. On the other hand, nonturbulent nebulae form large asteroids too quickly to explain long spreads in formation times, or the dearth of melted asteroids. Thus, the intensity of nebula turbulence (or "alpha ") is critical to the entire process. Theoretical understanding of nebula turbulence continues to evolve; while recent models of MRI (magneticallydriven) turbulence favor lowornoturbulence environments, purely hydrodynamic turbulence is making a comeback with three recently discovered mechanisms generating turbulence of moderate which do not rely on magnetic fields at all.

  2. Chondrites as samples of differentiated planetesimals

    Science.gov (United States)

    Elkins-Tanton, Linda; Weiss, Benjamin P.; Zuber, Maria T.

    2010-05-01

    Chondritic meteorites are unmelted, variably metamorphosed samples of the earliest solids of the solar system. A recent paleomagnetic study of CV chondrites suggests that their parent body was internally differentiated and produced a core magnetic dynamo (Carporzen et al., submitted, and this session). Here we show that a parent body that accreted to >250 km in radius by ~1.7 Ma after the formation of CAIs could retain a solid undifferentiated crust overlying a differentiated interior, and would be consistent with formational and evolutionary constraints on the CV parent body. Further, this body could have produced a magnetic field lasting more than 10 Ma. CV chondritic meteorites contain the oldest known solids: calcium-aluminum-rich inclusions (CAIs). The variety of metamorphic textures in ordinary chondrites motivated the "onion shell" model in which chondrites originated at varying depths within a parent body heated primarily by the short-lived radioisotope 26Al, with the highest metamorphic grade originating nearest the center. The large abundances and sizes of CAIs in CV chondrites have long suggested an early parent body accretion age. New Pb-Pb and Al-Mg ages of chondrules in CVs are consistent with the CV parent body having largely completed accretion by the youngest chondrule age of ~1.7-3 Ma. The CV chondrite parent body likely reached peak metamorphic temperatures around 7 to 10 Ma after CAIs, based on I-Xe chronometry for Allende and Mn-Cr chronometry for Mokoia. Bodies that accreted to more than >~20 km radius before ~1.3 to 3 Ma after the formation of CAIs likely contained sufficient 26Al to melt internally from the insulated cumulative effects of radiogenic heating. These early-accreting bodies will melt from the interior out, sometimes forming an interior magma ocean under a solid, conductive, undifferentiated shell. This shell would consist of the same chondritic material that made up the bulk accreting body before melting began. The presence of talc and the absence of serpentine indicate peak temperatures of ~300-350°C. Subsequent to the analysis of natural remanent magnetization in angrites, Carporzen et al. (2009, submitted, and this conference) have described how unidirectional magnetization in Allende is consistent with a long-lived internally generated field. The metamorphic, magnetic, and exposure age data collectively indicate a new model for the CV chondrite parent body in which interior melting is incomplete and the magma ocean remains capped by an undifferentiated chondritic shell. This conductive lid insulates the internal magma ocean, slowing its cooling and solidification by orders of magnitude while still allowing sufficient heat flux out of the core to produce a dynamo with intensities consistent with magnetization in Allende. Materials in the undifferentiated lid experienced varying metamorphic conditions. Bodies that are internally differentiated in the manner described here may well exist undetected in the asteroid belt. The shapes and masses of the two largest asteroids, 1 Ceres and 2 Pallas, can be consistent with differentiated interiors, conceivably with small iron cores with hydrated silicate or ice-silicate mantles. Other asteroids may have lost their hydrostatic shapes through later impacts, and their surfaces may never have been covered with erupted basalt; surfaces of these bodies may have remained chondritic throughout this process. Such surfaces will therefore be irregular, space-weathered primitive material, perhaps with highly altered or even differentiated material at the bottoms of the largest craters and in crater ejecta. This scenario can explain the mismatch between the enormous diversity (> 130) of parent bodies represented by achondrites and the paucity (< 10) of basaltic asteroids.

  3. From planetesimals to planets: volatile molecules

    CERN Document Server

    Marboeuf, Ulysse; Alibert, Yann; Cabral, Nahuel; Benz, Willy

    2014-01-01

    Solar and extrasolar planets are the subject of numerous studies aiming to determine their chemical composition and internal structure. In the case of extrasolar planets, the composition is important as it partly governs their potential habitability. Moreover, observational determination of chemical composition of planetary atmospheres are becoming available, especially for transiting planets. The present works aims at determining the chemical composition of planets formed in stellar systems of solar chemical composition. The main objective of this work is to provide valuable theoretical data for models of planet formation and evolution, and future interpretation of chemical composition of solar and extrasolar planets. We have developed a model that computes the composition of ices in planets in different stellar systems with the use of models of ice and planetary formation. We provide the chemical composition, ice/rock mass ratio and C:O molar ratio for planets in stellar systems of solar chemical compositio...

  4. Theory Uncertainty in Extracting the Proton's Weak Charge: White Paper

    CERN Document Server

    Gorchtein, Mikhail; Hurth, Tobias; Spiesberger, Hubert; Kumar, Krishna; Ramsey-Musolf, Michael J; Meyer, Harvey B

    2013-01-01

    We review the state-of-the-art and address open questions relative to the theory uncertainty of the $\\gamma-Z$ box contribution to the $A_{PV}$ measurement within the QWEAK experiment at Jefferson Lab. This white paper summarizes the contributions by participants and discussion sessions on this topic within the MITP Workshop on Precision Electroweak Physics held in Mainz, Germany, September 23 - October 11, 2013 \\url{http://indico.cern.ch/conferenceDisplay.py?confId=248072

  5. Contribution to contract theory

    Directory of Open Access Journals (Sweden)

    Pantelić Svetlana

    2016-01-01

    Full Text Available Oliver Hart and Bengt Holmstrom share the Nobel Prize in Economic Sciences for 2016, awarded to them by Sveriges Riksbank. They have been rewarded for their work in enhancing the design of contracts, i.e. arrangements connecting employers with employees or companies with clients, in other words, for their contribution to contract theory in the 1970s and 1980s. Their analysis of optimal contractual arrangements lays an intellectual foundation for designing policies and institutions in many areas, from bankruptcy legislation to political constitutions. Hart is an expert in contract theory, theory of the firm, corporate finance, and law and economics. His contribution to contract theory is exquisite when it comes to designing contracts which cover eventualities that cannot be precisely specified in advance.

  6. Contributions to statistics

    CERN Document Server

    Mahalanobis, P C

    1965-01-01

    Contributions to Statistics focuses on the processes, methodologies, and approaches involved in statistics. The book is presented to Professor P. C. Mahalanobis on the occasion of his 70th birthday. The selection first offers information on the recovery of ancillary information and combinatorial properties of partially balanced designs and association schemes. Discussions focus on combinatorial applications of the algebra of association matrices, sample size analogy, association matrices and the algebra of association schemes, and conceptual statistical experiments. The book then examines latt

  7. COINCO Strategy 2025 - Discussion Paper

    DEFF Research Database (Denmark)

    Jespersen, Per Homann; Jensen, Anne; Stroschein, Christoph

    companies in the corridor, attracting innovative international companies, and supporting the creation of new knowledge intensive businesses is thus at the core of the strategy. New areas of collaboration will have to be identified systematically. Cooperation among COINCO businesses have...... The regions and cities in the COINCO-corridor Oslo-Göteborg-Malmö-Copenhagen-Berlin have worked out a strategy proposal which is presented in this discussion paper. Behind the strategy is a political will to utilize mutual strengths and together become a leading player in a globalized world, based...... on common cultural, social and environmental values. The strategy comprises of a vision and more detailed aims and actions within three different areas: Corridor infrastructure, Innovation and Cooperation. In this way, the COINCO partners want to establish a political platform for transborder collaboration...

  8. Object technology: A white paper

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, S.R.; Arrowood, L.F.; Cain, W.D.; Stephens, W.M.; Vickers, B.D.

    1992-05-11

    Object-Oriented Technology (OOT), although not a new paradigm, has recently been prominently featured in the trade press and even general business publications. Indeed, the promises of object technology are alluring: the ability to handle complex design and engineering information through the full manufacturing production life cycle or to manipulate multimedia information, and the ability to improve programmer productivity in creating and maintaining high quality software. Groups at a number of the DOE facilities have been exploring the use of object technology for engineering, business, and other applications. In this white paper, the technology is explored thoroughly and compared with previous means of developing software and storing databases of information. Several specific projects within the DOE Complex are described, and the state of the commercial marketplace is indicated.

  9. Object technology: A white paper

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, S.R.; Arrowood, L.F.; Cain, W.D.; Stephens, W.M.; Vickers, B.D.

    1992-05-11

    Object-Oriented Technology (OOT), although not a new paradigm, has recently been prominently featured in the trade press and even general business publications. Indeed, the promises of object technology are alluring: the ability to handle complex design and engineering information through the full manufacturing production life cycle or to manipulate multimedia information, and the ability to improve programmer productivity in creating and maintaining high quality software. Groups at a number of the DOE facilities have been exploring the use of object technology for engineering, business, and other applications. In this white paper, the technology is explored thoroughly and compared with previous means of developing software and storing databases of information. Several specific projects within the DOE Complex are described, and the state of the commercial marketplace is indicated.

  10. Relativity on rotated graph paper

    Science.gov (United States)

    Salgado, Roberto B.

    2016-05-01

    We demonstrate a method for constructing spacetime diagrams for special relativity on graph paper that has been rotated by 45°. The diagonal grid lines represent light-flash worldlines in Minkowski spacetime, and the boxes in the grid (called "clock diamonds") represent units of measurement corresponding to the ticks of an inertial observer's light clock. We show that many quantitative results can be read off a spacetime diagram simply by counting boxes, with very little algebra. In particular, we show that the squared interval between two events is equal to the signed area of the parallelogram on the grid (called the "causal diamond") with opposite vertices corresponding to those events. We use the Doppler effect—without explicit use of the Doppler formula—to motivate the method.

  11. 29 CFR 570.63 - Occupations involved in the operation of paper-products machines, scrap paper balers, and paper...

    Science.gov (United States)

    2010-07-01

    ... machines, scrap paper balers, and paper box compactors (Order 12). 570.63 Section 570.63 Labor Regulations... involved in the operation of paper-products machines, scrap paper balers, and paper box compactors (Order..., scrap paper baler, paper box compactor, or vertical slotter. (ii) Platen die-cutting press,...

  12. Ecolabeled paper towels: consumer valuation and expenditure analysis.

    Science.gov (United States)

    Srinivasan, Arun K; Blomquist, Glenn C

    2009-01-01

    Ecolabeled paper towels are manufactured using post-consumer recycled material and sold in markets using a recycle logo. Environmentally conscious consumers purchase these paper towels and thereby contribute to improving environmental quality. In this paper, we estimate the implicit value placed by consumers on ecolabeled paper towels using a hedonic price function and conduct an expenditure analysis using Heckman's selection model. Using the data set from the Internet-based grocery stores called as Peapod we find that some consumers recognize ecolabels on paper towels and place a substantial, positive price premium on them. The expenditure analysis indicates that for the preferred functional form, the demand for ecolabeled paper towels is inelastic for environmentally conscious consumers. The simulated results from the selection model indicate that a small subsidy for ecolabeled paper towels will not substantially change consumers' purchase decisions.

  13. Recycling disposable cups into paper plastic composites.

    Science.gov (United States)

    Mitchell, Jonathan; Vandeperre, Luc; Dvorak, Rob; Kosior, Ed; Tarverdi, Karnik; Cheeseman, Christopher

    2014-11-01

    The majority of disposable cups are made from paper plastic laminates (PPL) which consist of high quality cellulose fibre with a thin internal polyethylene coating. There are limited recycling options for PPLs and this has contributed to disposable cups becoming a high profile, problematic waste. In this work disposable cups have been shredded to form PPL flakes and these have been used to reinforce polypropylene to form novel paper plastic composites (PPCs). The PPL flakes and polypropylene were mixed, extruded, pelletised and injection moulded at low temperatures to prevent degradation of the cellulose fibres. The level of PPL flake addition and the use of a maleated polyolefin coupling agent to enhance interfacial adhesion have been investigated. Samples have been characterised using tensile testing, dynamic mechanical analysis (DMA) and thermogravimetric analysis. Use of a coupling agent allows composites containing 40 wt.% of PPL flakes to increase tensile strength of PP by 50% to 30 MPa. The Young modulus also increases from 1 to 2.5 GPa and the work to fracture increases by a factor of 5. The work demonstrates that PPL disposable cups have potential to be beneficially reused as reinforcement in novel polypropylene composites.

  14. Factors contributing to adolescent obesity.

    Science.gov (United States)

    Al-Kloub, Manal I; Froelicher, Erika S

    2009-06-01

    Obesity in children is a significant public health concern. The prevalence of overweight and obesity in Jordanian children, and adolescents has increased in the last decade. The consequences of obesity to health in childhood and adulthood have both medical, and economic cost to individuals and society. This paper reviews the factors that contribute to adolescent obesity and emphasizes behavioral and environmental factors. An individual's behaviors such as increased consumption of high caloric foods, increased sedentary activity while decreasing physical activity has been identified as key issues in the development of obesity. Additionally, the current environment in homes, schools, and neighborhoods tend to discourage a healthy lifestyle. A comprehensive approach that involves the whole community is the best strategy for preventing adolescent obesity. Nurses are in a unique position to provide leadership in developing programs for healthier lifestyle choices for adolescents' and adoption of these goals into their daily lives.

  15. Replacing paper with digital recording.

    Science.gov (United States)

    Amin, Kawa

    2015-01-01

    Addressing the needs to achieve the highest standards at multidisciplinary team meetings at the Stroke Unit of Broomfield Hospital, an electronic version is applied instead of the traditional paper model. This is to ensure that patients within the unit are receiving appropriate care and their progress is monitored throughout their entire journey. This also enables the stroke team to retrieve old information anywhere in the hospital, electronically, from previous documentations to compare progress of rehabilitation. The electronic model also helps when assessing readmission or those who attend the stroke clinics to clarify new onset changes from residual weakness. The tool kit estimates Barthel Index score for activities of daily living and Rivermead Mobility Index for physical capacity assessment weekly as the team attending the meetings. The goals from all disciplines, physiotherapists, occupational therapists, speech and language therapists, and nurses are clearly documented along with patient cognition, emotion, and perception. This initiative commenced in late April 2013 and the first clinical outcome assessments performed at the beginning of September 2013, enabling the stroke team to assess rehabilitation activities and achievements. Front-line staff expressed satisfaction with the initiative model, which successfully managed to monitor and analyze the rehabilitation activities within the stroke unit.

  16. Challenge of Biotechnology (Review Paper

    Directory of Open Access Journals (Sweden)

    Malcolm R. Dando

    2001-10-01

    Full Text Available The unravelling of the human genetic code whose first draft was announced in June 2000 has rightly blood been hailed as a momentous achievement, opening thc book of life, certain to be the dominant technology of the 21st century, which will inform all about medicine and biology. and lead us to a total understanding of life. Simultaneously, concerns have been expressed about thc implications of this work. In the past, major new technologies have been used intensively for hostile purposes. What is thc challenge that biotechnology poses in this regard'? This review paper looks at the enormous changes in civil society that thc genomics revolution could bring. Against this background, thc growing concerns about its potential misuses have been reviewed. Thc strengths and weaknesses or the Biological and Toxin Weapons Convention (BTWC are then touched upon. The BTWC presently lacks an adequate verification mechanism. Although biotechnology has been used by human beings since prehistoric times (eg. making of bread. cheese. wines its scientific understanding came only in the latter part of the 19th century. Thc decisive turning point in the field came in the 1970s with the advent of genetic engineering. In the military context classical agents like anthrax and toxin remain the threat today. Although thc current level or sophistication for many biological agents is low, there is enormous potential for making more sophisticated weapons. It might be possible to specifically target the genetic makeup of different ethnic groups. The limited varieties of staple crops and the limited strains of modern animals make agriculture particularly open to attack. Another serious possibility is the impact of genomics in neuroscience. With a better understanding of cellular receptor systems and bioregulators, it is not inconceivable that new means would be evolved for disturbing the functions of the nervous system. Thc genomics revolution can be used for peaceful purposes

  17. CALL FOR PAPERS: Special issue on Spin Glasses

    Science.gov (United States)

    Coolen, Ton; Nishimori, Hidetoshi; Sourlas, Nicolas; Wong, Michael

    2007-10-01

    This is a call for contributions to a special issue of Journal of Physics A: Mathematical and Theoretical dedicated to the subject of the conference `Viewing The World Through Spin Glasses', in honour of David Sherrington on the occasion of his 65th birthday, 31 August-1 September 2007 (http://www.nottingham.ac.uk/\\verb.~.ppzjpg/DS2007/). Invited speakers and participants at that meeting and other researchers working in the field are invited to submit a research paper to this issue. The Editorial Board has invited Ton Coolen, Hidetoshi Nishimori, Nicolas Sourlas and Michael Wong to serve as Guest Editors for the special issue. Their criteria for acceptance of contributions are as follows: •The subject of the paper should relate to the subject of the conference (see the website of the conference http://www.nottingham.ac.uk/\\verb.~.ppzjpg/DS2007/). •Contributions will be refereed and processed according to the usual procedure of the journal. •Conference papers may be based on already published work but should either contain significant additional new results and/or insights or give a survey of the present state of the art, a critical assessment of the present understanding of a topic, and a discussion of open problems. •Papers submitted by non-participants should be original and contain substantial new results. The guidelines for the preparation of contributions are the following: •The DEADLINE for submission of contributions is 1 December 2007. This deadline will allow the special issue to appear in July 2008. •There is a nominal page limit of 16 printed pages per contribution. For papers exceeding this limit, the Guest Editors reserve the right to request a reduction in length. •Further advice on publishing your work in Journal of Physics A: Mathematical and Theoretical may be found at www.iop.org/Journals/jphysa. •Contributions to the special issue should, if possible, be submitted electronically by web upload at www.iop.org/Journals/jphysa or by

  18. Students' Oral Contributions to Classroom Verbal Interaction.

    Science.gov (United States)

    Dunkin, Michael J.

    This review of the literature related to research on oral communication in the classroom pursues two issues: the types of oral contributions students make and whether those types are related to school achievement. In considering research on oral communication in classrooms, the paper looks at information that considers whether the communication…

  19. Lattice QCD and the Balkan physicists contribution

    CERN Document Server

    Borici, Artan

    2015-01-01

    This is a paper based on the invited talk the author gave at the 9th Balkan Physical Union conference. It contains some of the main achievements of lattice QCD simulations followed by a list of Balkan physicists who have contributed to the project.

  20. The value contribution of strategic foresight

    DEFF Research Database (Denmark)

    Rohrbeck, René; Schwarz, Jan Oliver

    2013-01-01

    This paper focuses on exploring the potential and empirically observable value creation of strategic foresight activities in firms. We first review the literature on strategic foresight, innovation management and strategic management in order to identify the potential value contributions. We use...

  1. Do School Lunches Contribute to Childhood Obesity?

    Science.gov (United States)

    Schanzenbach, Diane Whitmore

    2009-01-01

    This paper assesses whether school lunches contribute to childhood obesity. I employ two methods to isolate the causal impact of school lunches on obesity. First, using panel data, I ?nd that children who consume school lunches are more likely to be obese than those who brown bag their lunches even though they enter kindergarten with the same…

  2. White Paper Social media literacy: Time for an update!

    OpenAIRE

    Donoso Navarrete, Veronica; Verdoodt, Valerie

    2014-01-01

    The EMSOC White Paper White Paper “Social Media Literacy: Time for an Update!” integrates the contributions of communication, legal, educational and user experience researchers who looked into current social media challenges from the perspective of their various disciplines. It also incorporates the views of practitioners and experts in the field, which were collected during a dedicated expert workshop in October 2014 in Brussels. Their ideas have been invaluable for the elaboration of practi...

  3. Mathematical foundation of geodesy selected papers of Torben Krarup

    CERN Document Server

    Borre, K

    2006-01-01

    This volume contains selected papers by Torben Krarup, one of the most important geodesists of the 20th century. The collection includes the famous booklet "A Contribution to the Mathematical Foundation of Physical Geodesy" from 1969, the unpublished "Molodenskij letters" from 1973, the final version of "Integrated Geodesy" from 1978, "Foundation of a Theory of Elasticity for Geodetic Networks" from 1974, as well as trend-setting papers on the theory of adjustment.

  4. 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.

  5. Seneca's contribution to astronomy

    Science.gov (United States)

    Pljakić, Branislava

    2002-04-01

    In this paper is shown the work of Lucius Anaeus Seneca "Natural Questiones", Book 7th relating to comets from 1st to 14th as well as 24th chapter. Although Seneca was not an astronomer he reached some very interesting conclusions. Besides that he introduces us in his work to the knowledge which had been gained before him as well as to the then obtained fallacies.

  6. Factors contributing to fossilization

    Institute of Scientific and Technical Information of China (English)

    徐菁

    2010-01-01

    As the most prominent feature of interlanguage, fossilization is a complex and essential topic in the field of SLA research. Various causes, in spite quantity of them are only theories, have been studied by different researchers from multiple points of view. Daiwei Dong(1990) has pointed out that virtually every inaccurate cause leads to language fossilization. This paper tries to conclude update causes of fossilization.

  7. Contributing from the margins

    DEFF Research Database (Denmark)

    Chimirri, Niklas Alexander

    /herself as a contributor to an investigated practice, as inextricably entangled with the conducts of life of the others in relation to the conditions in practice. Doing research in the kindergarten thus becomes a mutual and collective endeavor, to which pedagogues, parents, children, and the researcher contribute. Even...... empirical study, I focused on kindergarten children’s first-person perspectives on the electronic media technologies they deemed subjectively relevant for conducting everyday life in the practice of their kindergarten. The concept of the children’s perspectives opens possibilities for transcending...... the widespread, one-sided explanations of the relationship between a child and technology, which ascribe agency either to the child or to the technology. However, attempts to access these perspectives raises a number of epistemological and ethical-political challenges, most crucially regarding the concrete role...

  8. A Profile of Corporate Contributions.

    Science.gov (United States)

    Smith, Hayden W.

    The extent and distribution of charitable contributions by corporations were studied. In addition to a history of giving from 1936 to 1981, information is presented on corporate contributions in 1977 in terms of the distribution of companies (1) by size of contributions, (2) by contributions as percentage of net income, (3) by industry, and (4) by…

  9. Response to the National Career Development Strategy Green Paper

    Science.gov (United States)

    Australian Journal of Career Development, 2012

    2012-01-01

    The Career Development Association of Australia (CDAA) congratulates the Commonwealth Government on the development of the National Career Development Strategy Green Paper. This is a timely and important document that provides a framework to demonstrate the central contribution that career development services play in supporting individuals,…

  10. Assessment factors for human health risk assessment: A discussion paper

    NARCIS (Netherlands)

    Vermeire, T.; Stevenson, H.; Pieters, M.N.; Rennen, M.; Slob, W.; Hakkert, B.C.

    1999-01-01

    The general goal of this discussion paper is to contribute toward the further harmonization of human health risk assessment. It first discusses the development of a formal, harmonized set of assessment factors. The status quo with regard to assessment factors is reviewed, that is, the type of factor

  11. The 1989 JSC bibliography of scientific and technical papers

    Science.gov (United States)

    Hutchins, Nancy (Compiler)

    1991-01-01

    This document is a compilation of Lyndon B. Johnson Space Center contributions to the scientific and technical literature in aerospace and life sciences made during calendar year 1989. Citations include NASA formal series reports, journal articles, conference and symposium presentations, papers published in proceedings or other collective works, and seminar and workshop results.

  12. Response to the National Career Development Strategy Green Paper

    Science.gov (United States)

    Australian Journal of Career Development, 2012

    2012-01-01

    The Career Development Association of Australia (CDAA) congratulates the Commonwealth Government on the development of the National Career Development Strategy Green Paper. This is a timely and important document that provides a framework to demonstrate the central contribution that career development services play in supporting individuals,…

  13. Papers and Studies in Contrastive Linguistics. Volume Eighteen.

    Science.gov (United States)

    Fisiak, Jacek, Ed.; Drozdzial, Krystyna, Ed.

    A collection of 14 papers in contrastive linguistics includes: "Some Comments on Language Data in Contrastive Analysis" (Ruta Nagucka); "Contrastive Sociolinguistics Reconsidered" (Karol Janicki); "Variations in Polish Nasal /e/: A Contribution to the Development of Contrastive Sociolinguistic Methodology" (Jane Johnson); "Languages in Contact and…

  14. China issued First White Paper on Foreign Trade

    Institute of Scientific and Technical Information of China (English)

    Wanzy

    2012-01-01

    On Dec. 7th, 2011, on the occasion of the lOth anniversary of China's World Trade Organization (WTO) accession, the State Council of PRC issued its first white paper on foreign trade, highlighting its achievements in boosting foreign trade and its contribution to the world economy.

  15. From Paper to Internet: Academic Libraries in Transition

    Institute of Scientific and Technical Information of China (English)

    周欣平

    2006-01-01

    This paper examines the current trends, challenges, and issues facing all libraries, and discusses the strategies that academic libraries, in particular, are taking to transform their services, manage their organizations, and preserve their digital assets. It demonstrates how a network of distributed services, resource sharing, co-investment, and access integration contributes to sustainable library development.

  16. M and T in the paper and converting industries

    Energy Technology Data Exchange (ETDEWEB)

    Gotel, D.; Bateman, B.; Marriott, A.

    1987-12-01

    The application of a monitoring and targeting (M and T) system in about half of the paper mills in the UK has resulted in a significant improvement in energy efficiency. A standardized method of monitoring and reporting energy use has led to meaningful comparisons between individual businesses or sites and has contributed to the setting of realistic performance improvement targets. The potential for extending M and T energy management programmes to other paper mills and to the paper and board converting industry is considered.

  17. Development and Assessment of Collaboration, Teamwork, and Communication. TLTC Paper No. 4. CRLT Occasional Paper No. 35

    Science.gov (United States)

    Kusano, Stephanie M.; Conger, Amy J.; Wright, Mary C.

    2016-01-01

    This Occasional Paper focuses on fostering and assessing collaboration, teamwork, and communication. This involves encouraging students to appreciate and leverage diverse contributions to a task, developing their ability to cooperate with others towards common purposes, and increasing their capacity to communicate effectively with teammates,…

  18. Consensus Paper: Management of Degenerative Cerebellar Disorders

    Science.gov (United States)

    Ilg, W.; Bastian, A. J.; Boesch, S.; Burciu, R. G.; Celnik, P.; Claaßen, J.; Feil, K.; Kalla, R.; Miyai, I.; Nachbauer, W.; Schöls, L.; Strupp, M.; Synofzik, M.; Teufel, J.

    2015-01-01

    Treatment of motor symptoms of degenerative cerebellar ataxia remains difficult. Yet there are recent developments that are likely to lead to significant improvements in the future. Most desirable would be a causative treatment of the underlying cerebellar disease. This is currently available only for a very small subset of cerebellar ataxias with known metabolic dysfunction. However, increasing knowledge of the pathophysiology of hereditary ataxia should lead to an increasing number of medically sensible drug trials. In this paper, data from recent drug trials in patients with recessive and dominant cerebellar ataxias will be summarized. There is consensus that up to date, no medication has been proven effective. Aminopyridines and acetazolamide are the only exception, which are beneficial in patients with episodic ataxia type 2. Aminopyridines are also effective in a subset of patients presenting with downbeat nystagmus. As such, all authors agreed that the mainstays of treatment of degenerative cerebellar ataxia are currently physiotherapy, occupational therapy, and speech therapy. For many years, well-controlled rehabilitation studies in patients with cerebellar ataxia were lacking. Data of recently published studies show that coordinative training improves motor function in both adult and juvenile patients with cerebellar degeneration. Given the well-known contribution of the cerebellum to motor learning, possible mechanisms underlying improvement will be outlined. There is consensus that evidence-based guidelines for the physiotherapy of degenerative cerebellar ataxia need to be developed. Future developments in physiotherapeutical interventions will be discussed including application of non-invasive brain stimulation. PMID:24222635

  19. Contribution to postnonclassical psychopathology.

    Directory of Open Access Journals (Sweden)

    Quintino-Aires J.

    2014-09-01

    Full Text Available Any psychological paradigm needs a psychopathological system that helps professionals to describe and explain the behavioral expressions that deviate from “normal” (whether this term is used with the semantic property of statistical or ideal adaptations. In this work, I seek to present the system that I have been developing since 1998 among the psychologists at the Instituto Vegotsky de Lisboa (Vygotsky Institute of Lisbon, Portugal, to understand psychopathology with regard to the vygotskian approach. It was conceived and designed according to the work of Rita Mendes Leal and her contribution to socioemotional development theory, AR Luria’s systemic and dynamic theory of the human brain, the theory of Activity (dyatel’nost of AN Leont’ev, and the psychopathological German school of E Kraepelin, presented and disseminated in Portugal in the early twentieth century by Professor Sobral Cid. It is intended to be a proposal to colleagues who are interested in postnonclassical psychology and a request for arguments.

  20. DEDUCTIBILITY OF CONTRIBUTIONS TO VOLUNTARY PRIVATE PENSIONS

    Directory of Open Access Journals (Sweden)

    LILIANA MUNTEAN

    2011-01-01

    Full Text Available The present paper approaches the notion of public and private pension in Romania. Pension can be seen in terms of a replacement income to individuals whose age no longer affords to operate in the labour market. Pension reform in Romania has allowed besides the public pension system, called Pillar I, which is a distributive system based on solidarity between generations also a private pension system that records the contributions of participants in individual accounts, based on capitalization, investment and accumulation of these contributions.

  1. Canadian contributions studies for the WFIRST instruments

    Science.gov (United States)

    Lavigne, J.-F.; Rowlands, N.; Grandmont, F. J.; Lafrenière, D.; Marois, C.; Daigle, O.; Thibault, S.; Schade, D.; Artigau, É.; Brousseau, D.; Maire, J.; Cretot-Richert, G.; Ducharme, M.-È.; Levesque, L. E.; Laurin, D.; Dupuis, J.

    2016-07-01

    WFIRST-AFTA is the NASA's highest ranked astrophysics mission for the next decade that was identified in the New World, New Horizon survey. The mission scientific drivers correspond to some of the deep questions identified in the Canadian LRP2010, and are also of great interest for the Canadian scientists. Given that there is also a great interest in having an international collaboration in this mission, the Canadian Space Agency awarded two contracts to study a Canadian participation in the mission, one related to each instrument. This paper presents a summary of the technical contributions that were considered for a Canadian contribution to the coronagraph and wide field instruments.

  2. Contribution to encyclopedia of thermal stresses

    Science.gov (United States)

    Taler, Jan; Ocłoń, Pawel

    2015-06-01

    This paper lists the contribution in the international interdisciplinary reference - Encyclopedia of Thermal Stresses (ETS). The ETS, edited by the world famous expert in field of Thermal Stresses - Professor Richard Hetnarski from Rochester Institute of Technology, was published by Springer in 2014. This unique Encyclopedia, subdivided into 11 volumes is the most extensive and comprehensive work related to the Thermal Stresses topic. The entries were carefully prepared by specialists in the field of thermal stresses, elasticity, heat conduction, optimization among others. The Polish authors' contribution within this work is significant; over 70 entries were prepared by them.

  3. Analogies in science education: contributions and challenges

    Directory of Open Access Journals (Sweden)

    Maria da Conceição Duarte

    2005-03-01

    Full Text Available An analogy is a comparison between domains of knowledge that have similarities at the levels of characteristics and relationships. Several authors highlight the importance of this tool in the teaching and learning of difficult scientific concepts. Nevertheless, some problems associated to the use of analogies have been found. This paper aims at contributing to a better understanding of the use of analogies in science education, by means of a review of the state of art regarding this matter. It will take into account its contribution to science education as well as the challenges to further research

  4. CALL FOR PAPERS: Progress in Supersymmetric Quantum Mechanics

    Science.gov (United States)

    2003-12-01

    This is a call for contributions to a special issue of Journal of Physics A: Mathematical and General dedicated to the subject of Supersymmetric Quantum Mechanics as featured in the International Conference in Supersymmetric Quantum Mechanics (PSQM03), 15--19 July 2003, University of Valladolid, Spain (http://metodos.fam.cie.uva.es/~susy_qm_03/). Participants at that meeting, as well as other researchers working in this area or in related fields, are invited to submit a research paper to this issue. The Editorial Board has invited Irina Areféva, David J Fernández, Véronique Hussin, Javier Negro, Luis M Nieto and Boris F Samsonov to act as Guest Editors for the special issue. Their criteria for acceptance of contributions are as follows: bullet The subject of the paper should be in the general area covered by the PSQM03 conference. bullet Contributions will be refereed and processed according to the usual mechanisms of the journal. bullet Papers should present substantial new results (they should not be simply reviews of authors' own work that is already published elsewhere). The guidelines for the preparation of contributions are as follows: bullet DEADLINE for submission of contributions is 15 January 2004. This deadline will allow the special issue to appear in approximately September 2004. bullet There is a page limit of 15 pages per research contribution. Further advice on publishing your work in Journal of Physics A: Mathematical and General may be found at www.iop.org/Journals/jphysa. bullet Contributions to the special issue should if possible be submitted electronically at www.iop.org/Journals/jphysa or by e-mail to jphysa@iop.org, quoting `JPhysA special issue --- PSQM03'. Submissions should ideally be in either standard LaTeX form or Microsoft Word. Please see the web site for further information on electronic submissions. bullet Authors unable to submit by email may send hard copy contributions to: Journal of Physics A, Institute of Physics Publishing

  5. EMSL Contribution Plan

    Energy Technology Data Exchange (ETDEWEB)

    Campbell, Allison A.

    2008-12-01

    This Contribution Plan is EMSL’s template for achieving our vision of simultaneous excellence in all aspects of our mission as a national scientific user facility. It reflects our understanding of the long-term stewardship we must work toward to meet the scientific challenges faced by the Department of Energy (DOE) and the nation. During the next decade, we will implement the strategies contained in this Plan, working closely with the scientific community, our advisory committees, DOE’s Office of Biological and Environmental Research, and other key stakeholders. This Plan is fully aligned with the strategic plans of DOE, its Office of Science, and the Pacific Northwest National Laboratory (PNNL). We recognize that shifts in science and technology, national priorities, and resources made available through the Federal budget process create planning uncertainties and, ultimately, a highly dynamic planning environment. Accordingly, this Plan should be viewed as a living document and we continually evaluate the changing needs and opportunities posed by our stakeholders (i.e., DOE, users, staff, advisory committees), work closely with them to understand and respond to those changes, and align our strategy accordingly. This Plan is organized around two sections. Section 1 describes our vision and four strategic outcomes: 1) Scientific Innovation, 2) Capabilities that Transform Science, 3) Outstanding Management and Operations, and Engaged and Proactive Users. These outcomes provide the framework for seven critical actions we must take during the next 3 to 5 years: 1) Establishing leadership in EMSL science themes, 2) building and deploying transformational capabilities, 3) integrating computation with experiment, 4) ensuring EMSL’s workforce meets the scientific challenges of the future, 5) creating partnerships, 6) attracting and engaging users in EMSL’s long-term strategy, and 7) building a research infrastructure that meets emerging scientific needs. Section 2

  6. How to write English scientific paper easily

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyeong Sun

    2010-07-15

    This book covers definition of paper, how to write paper, as well as proofreading of paper and process of publication. It explains necessity and kinds of paper, organizations and form of paper, evaluation of paper, titles, abstracts, introductions, method of study, results, considerations, conclusions, acknowledgement and epilogue, reference, writers, pictures and tables, tense and analysis of sentences, submission of paper and ethics of publication, plagiarism, confirmation of items before writing paper, matters to be attended to drafting, and criteria and assessment of the examination of paper.

  7. Contributions from Women to the Radiation Sciences: A Brief History.

    Science.gov (United States)

    Martinez, Nicole E

    2017-04-01

    Contributions from men to radiation science are well known, particularly the early contributions from such luminaries as William Roentgen, James Chadwick, Niels Bohr, Robert Oppenheimer, and the like. Although not ignored per se, beyond Marie Curie and Lise Meitner, the contributions of female nuclear scientists are not as widely recognized. This paper provides a concise historical summary of contributions to radiation science from the discovery of radiation through the current status of international leadership within the radiation protection community. Beyond lead scientists and academics, this paper also considers support personnel as well as the role women have played in the advancement of radiation epidemiology.

  8. MAGIC contributions to the 32nd International Cosmic Ray Conference

    CERN Document Server

    Aleksić, J; Antonelli, L A; Antoranz, P; Asensio, M; Backes, M; Barrio, J A; Bastieri, D; González, J Becerra; Bednarek, W; Berdyugin, A; Berger, K; Bernardini, E; Biland, A; Blanch, O; Bock, R K; Boller, A; Bonnoli, G; Tridon, D Borla; Braun, I; Bretz, T; Cañellas, A; Carmona, E; Carosi, A; Colin, P; Colombo, E; Contreras, J L; Cortina, J; Cossio, L; Covino, S; Dazzi, F; De Angelis, A; De Caneva, G; del Pozo, E De Cea; De Lotto, B; Mendez, C Delgado; Ortega, A Diago; Doert, M; Domínguez, A; Prester, D Dominis; Dorner, D; Doro, M; Eisenacher, D; Elsaesser, D; Ferenc, D; Fonseca, M V; Font, L; Fruck, C; López, R J García; Garczarczyk, M; Garrido, D; Giavitto, G; Godinović, N; Hadasch, D; Häfner, D; Herrero, A; Hildebrand, D; Höhne-Mönch, D; Hose, J; Hrupec, D; Jogler, T; Kellermann, H; Klepser, S; Krähenbühl, T; Krause, J; Kushida, J; La Barbera, A; Lelas, D; Leonardo, E; Lindfors, E; Lombardi, S; López, M; López-Oramas, A; Lorenz, E; Makariev, M; Maneva, G; Mankuzhiyil, N; Mannheim, K; Maraschi, L; Marcote, B; Mariotti, M; Martínez, M; Mazin, D; Meucci, M; Miranda, J M; Mirzoyan, R; Moldón, J; Moralejo, A; Munar-Adrover, P; Nieto, D; Nilsson, K; Orito, R; Otte, N; Oya, I; Paneque, D; Paoletti, R; Pardo, S; Paredes, J M; Partini, S; Perez-Torres, M A; Persic, M; Peruzzo, L; Pilia, M; Pochon, J; Prada, F; Moroni, P G Prada; Prandini, E; Gimenez, I Puerto; Puljak, I; Reichardt, I; Reinthal, R; Rhode, W; Ribó, M; Rico, J; Rissi, M; Rügamer, S; Saggion, A; Saito, K; Saito, T Y; Salvati, M; Satalecka, K; Scalzotto, V; Scapin, V; Schultz, C; Schweizer, T; Shayduk, M; Shore, S N; Sillanpää, A; Sitarek, J; Snidaric, I; Sobczynska, D; Spanier, F; Spiro, S; Stamatescu, V; Stamerra, A; Steinke, B; Storz, J; Strah, N; Surić, T; Takalo, L; Takami, H; Tavecchio, F; Temnikov, P; Terzić, T; Tescaro, D; Teshima, M; Tibolla, O; Torres, D F; Treves, A; Uellenbeck, M; Vankov, H; Vogler, P; Wagner, R M; Weitzel, Q; Zabalza, V; Zandanel, F; Zanin, R

    2011-01-01

    Compilation of the papers contributed by the MAGIC collaboration to the 32nd International Cosmic Ray Conference, which took place between August 11 and 18, 2011 in Beijing, China. The papers are sorted in 6 categories: Overview and Highlight papers; Instrument, software and techniques; Galactic sources; Extragalactic sources; Multi-wavelength and joint campaigns; Fundamental physics, dark matter and cosmic rays.

  9. Contributions to Persistence Theory

    Directory of Open Access Journals (Sweden)

    Du Dong

    2014-12-01

    Full Text Available Persistence theory discussed in this paper is an application of algebraic topology (Morse Theory [29] to Data Analysis, precisely to qualitative understanding of point cloud data, or PCD for short. PCD can be geometrized as a filtration of simplicial complexes (Vietoris-Rips complex [25] [36] and the homology changes of these complexes provide qualitative information about the data. Bar codes describe the changes in homology with coefficients in a fixed field. When the coefficient field is ℤ2, the calculation of bar codes is done by ELZ algorithm (named after H. Edelsbrunner, D. Letscher, and A. Zomorodian [20]. When the coefficient field is ℝ, we propose an algorithm based on the Hodge decomposition [17]. With Dan Burghelea and Tamal K. Dey we developed a persistence theory which involves level sets discussed in Section 4. We introduce and discuss new computable invariants, the “relevant level persistence numbers” and the “positive and negative bar codes”, and explain how they are related to the bar codes for level persistence. We provide enhancements and modifications of ELZ algorithm to calculate such invariants and illustrate them by examples.

  10. Molecular contributions to conservation

    Science.gov (United States)

    Haig, Susan M.

    1998-01-01

    Recent advances in molecular technology have opened a new chapter in species conservation efforts, as well as population biology. DNA sequencing, MHC (major histocompatibility complex), minisatellite, microsatellite, and RAPD (random amplified polymorphic DNA) procedures allow for identification of parentage, more distant relatives, founders to new populations, unidentified individuals, population structure, effective population size, population-specific markers, etc. PCR (polymerase chain reaction) amplification of mitochondrial DNA, nuclear DNA, ribosomal DNA, chloroplast DNA, and other systems provide for more sophisticated analyses of metapopulation structure, hybridization events, and delineation of species, subspecies, and races, all of which aid in setting species recovery priorities. Each technique can be powerful in its own right but is most credible when used in conjunction with other molecular techniques and, most importantly, with ecological and demographic data collected from the field. Surprisingly few taxa of concern have been assayed with any molecular technique. Thus, rather than showcasing exhaustive details from a few well-known examples, this paper attempts to present a broad range of cases in which molecular techniques have been used to provide insight into conservation efforts.

  11. Contributions of the Evolutive Perspective for Gerontology

    Directory of Open Access Journals (Sweden)

    Briseida Dôgo de Resende

    2011-09-01

    Full Text Available This paper presents the contributions that researches from Ethology and Evolutive Psychology can bring to Gerontology. From this perspective, human behavior may be understood under the light of Natural Selection. Thus, it is extremely important to consider how society and environment during human evolution were. This comprehension may facilitate the knowledge about how the mind and human society work, and may help to build a modern environment more similar to that of our ancestors. This paper introduces examples of evolutionary researches related to important aspects for gerontology, such as bereavement, depression and the role of grandmothers for raising children.

  12. Reductions for Entrepreneurs in Health Insurance Contributions

    Directory of Open Access Journals (Sweden)

    Paweł Lenio

    2014-09-01

    Full Text Available This paper describes the reductions for entrepreneurs in health insurance contributions. Only entrepreneurs from specific social groups can take advantage of said reductions. They apply only to people retired, on pensions or handicapped. The reductions are also dependent on the potential recipient's income and revenue of the company. Handicapped entrepreneurs can benefit from some additional privileges as well. Author analyzes the legal regulations behind these reductions and exposes their shortcomings which cause the benefits to be rarely used.

  13. Reductions for Entrepreneurs in Health Insurance Contributions

    OpenAIRE

    Paweł Lenio

    2014-01-01

    This paper describes the reductions for entrepreneurs in health insurance contributions. Only entrepreneurs from specific social groups can take advantage of said reductions. They apply only to people retired, on pensions or handicapped. The reductions are also dependent on the potential recipient's income and revenue of the company. Handicapped entrepreneurs can benefit from some additional privileges as well. Author analyzes the legal regulations behind these reductions and exposes their sh...

  14. De Finetti's contribution to probability and statistics

    OpenAIRE

    Cifarelli, Donato Michele; Regazzini, Eugenio

    1996-01-01

    This paper summarizes the scientific activity of de Finetti in probability and statistics. It falls into three sections: Section 1 includes an essential biography of de Finetti and a survey of the basic features of the scientific milieu in which he took the first steps of his scientific career; Section 2 concerns de Finetti's work in probability: (a) foundations, (b) processes with independent increments, (c) sequences of exchangeable random variables, and (d) contributions which fall within ...

  15. 21 CFR 872.6140 - Articulation paper.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Articulation paper. 872.6140 Section 872.6140 Food... DEVICES DENTAL DEVICES Miscellaneous Devices § 872.6140 Articulation paper. (a) Identification. Articulation paper is a device composed of paper coated with an ink dye intended to be placed between the...

  16. 27 CFR 40.351 - Cigarette papers.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Cigarette papers. 40.351... OF THE TREASURY (CONTINUED) TOBACCO MANUFACTURE OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Manufacture of Cigarette Papers and Tubes Taxes § 40.351 Cigarette papers....

  17. 27 CFR 41.34 - Cigarette papers.

    Science.gov (United States)

    2010-04-01

    ... 27 Alcohol, Tobacco Products and Firearms 2 2010-04-01 2010-04-01 false Cigarette papers. 41.34... OF THE TREASURY (CONTINUED) TOBACCO IMPORTATION OF TOBACCO PRODUCTS, CIGARETTE PAPERS AND TUBES, AND PROCESSED TOBACCO Taxes Tax Rates § 41.34 Cigarette papers. Cigarette papers are taxed at the...

  18. Wind Speed Measurement by Paper Anemometer

    Science.gov (United States)

    Zhong, Juhua; Cheng, Zhongqi; Guan, Wenchuan

    2011-01-01

    A simple wind speed measurement device, a paper anemometer, is fabricated based on the theory of standing waves. In providing the working profile of the paper anemometer, an experimental device is established, which consists of an anemometer sensor, a sound sensor, a microphone, paper strips, a paper cup, and sonic acquisition software. It shows…

  19. Wind Speed Measurement by Paper Anemometer

    Science.gov (United States)

    Zhong, Juhua; Cheng, Zhongqi; Guan, Wenchuan

    2011-01-01

    A simple wind speed measurement device, a paper anemometer, is fabricated based on the theory of standing waves. In providing the working profile of the paper anemometer, an experimental device is established, which consists of an anemometer sensor, a sound sensor, a microphone, paper strips, a paper cup, and sonic acquisition software. It shows…

  20. Paper-based batteries: a review.

    Science.gov (United States)

    Nguyen, Thu H; Fraiwan, Arwa; Choi, Seokheun

    2014-04-15

    There is an extensively growing interest in using paper or paper-like substrates for batteries and other energy storage devices. Due to their intrinsic characteristics, paper (or paper-like) batteries show outstanding performance while retaining low cost, multifunctionality, versatility, flexibility and disposability. In this overview, we review recent achievements in paper (or paper-like) batteries as well as their applications. Various types of paper power devices are discussed including electrochemical batteries, biofuel cells, lithium-ion batteries, supercapacitors, and nanogenerators. Further scientific and technological challenges in this field are also discussed.

  1. Selected papers for global `95 concerning plutonium

    Energy Technology Data Exchange (ETDEWEB)

    Sutcliffe, W.G. [ed.

    1996-06-14

    This report contains selected papers from the Global `95 Conference ``Evaluation of Emerging Nuclear Fuel Cycle Systems,`` held in Versailles, Sept. 11-14, 1995. The 11 papers in Part I are from ``Benefits and Risks of Reprocessing`` sessions. The 7 papers in Part II are some of the more interesting poster papers that relate to the use of Pu for power generation. Finally, the 3 papers are on the topic of management and disposition of Pu from retired nuclear weapons.

  2. Contribution of Journals to Academic Disciplines

    Directory of Open Access Journals (Sweden)

    Lee, Hye-Young

    2015-03-01

    Full Text Available This research uses a new approach to analyze the extent of influence journal papers have on the progress of varied research fields by estimation of subject-based influence on research other than impact factor that relies on citation index. It is initiated with the hypothesis that earlier established citation relations between journal and citing paper, which reveals the research field that contains the highest citation index and hence has received the greatest contribution from a particular journal, would have inconsistent contribution to the research field over the year of journal publication. The target research is primarily 128 journal papers and 4,123 citing papers from Information Systems Research published in the years 2001, 2004, 2007, and 2010. The characteristics of citation history and hallmarks of research field of citing papers were studied and analysis on significant distinction between citing fields based on the year of publication was performed. The analysis results show the order of citation rate to be highest from Computer Science (2,221 cases, Business & Economics (2,191 cases, and Information Science & Library Science (1,901 cases. The citation history of the journal, nonetheless, indicates increase in citation during 2-3 years after the earliest publication till it achieves constant citation. The statistical analysis shows significant variation in citing fields in accordance with the publication year; especially in 2010, journal contribution has increased in the fields of Business & Economics, Operations Research & Management Science, and Health Care Sciences & Services but, however, is reduced in Education & Educational Research and Social Sciences - Other Topics.

  3. Balanced Contributions for Multi-Issue Allocation Situations

    NARCIS (Netherlands)

    Lorenzo-Freire, S.; Alonso-Meijide, J.M.; Casas-Mendez, B.; Hendrickx, R.L.P.

    2005-01-01

    In this paper we introduce a property of balanced contributions in the context of multi-issue allocation situations.Using this property, we characterise the run-to-thebank rule for multi-issue allocation situations.

  4. A new contribution to the conventional atmospheric neutrino flux

    CERN Document Server

    Gaisser, Thomas K

    2014-01-01

    Atmospheric neutrinos are an important background to astrophysical neutrino searches, and are also of considerable interest in their own right. This paper points out that the contribution to conventional atmospheric $\

  5. 100 top-cited scientific papers in limb prosthetics

    OpenAIRE

    Eshraghi, Arezoo; Osman, Noor Azuan Abu; Gholizadeh, Hossein; Ali, Sadeeq; Shadgan, Babak

    2013-01-01

    Research has tremendously contributed to the developments in both practical and fundamental aspects of limb prosthetics. These advancements are reflected in scientific articles, particularly in the most cited papers. This article aimed to identify the 100 top-cited articles in the field of limb prosthetics and to investigate their main characteristics. Articles related to the field of limb prosthetics and published in the Web of Knowledge database of the Institute for Scientific Information (...

  6. Contributions of Alan C. Lazer to mathematical population dynamics

    Directory of Open Access Journals (Sweden)

    Chris Cosner

    2000-10-01

    Full Text Available This paper is a survey of the contributions that Professor Alan C. Lazer has made to the mathematical theory of population dynamics. Specific areas where Professor Lazer has made important contributions include time periodic population models with diffusion and nonautonomous models for many competing species.

  7. Computer Aided Flowsheet Design using Group Contribution Methods

    DEFF Research Database (Denmark)

    Bommareddy, Susilpa; Eden, Mario R.; Gani, Rafiqul

    In this paper, a systematic group contribution based framework is presented for synthesis of process flowsheets from a given set of input and output specifications. Analogous to the group contribution methods developed for molecular design, the framework employs process groups to represent...

  8. Computer Aided Flowsheet Design using Group Contribution Methods

    DEFF Research Database (Denmark)

    Bommareddy, Susilpa; Eden, Mario R.; Gani, Rafiqul

    2011-01-01

    In this paper, a systematic group contribution based framework is presented for synthesis of process flowsheets from a given set of input and output specifications. Analogous to the group contribution methods developed for molecular design, the framework employs process groups to represent...

  9. The contribution of Ukrainian physicians to world medicine.

    Science.gov (United States)

    Hanitkevych, Yoroslav

    2009-06-01

    This paper gives information about fifty physicians, from the Middle Ages to the present, who have enriched world medicine. It describes the contribution made both by Ukrainian physicians and those of other nationalities, who worked in Ukrainian lands occupied by Russia, Poland, Austria-Hungary and Romania. The paper notes the contribution that these physicians have made to modern medical science, paying special attention to their achievements and published work.

  10. Position Paper on Intelligent Supply Chains

    DEFF Research Database (Denmark)

    Møller, Charles

    This paper is intended to present and to analyze the concept of the Intelligent Supply Chain (ISC). The purpose of the paper is to: 1) Clarify the concept of the intelligent supply chain; 2) Identify emerging research opportunities; and 3) Specify a research engagement model for further exploration...... of the concept. The ideas and notions integrated and presented in this paper have evolved over a period of one or two years and have partly been presented in other papers. This paper is a mash up from different sources and it is intended for communicating the ideas. Thus the aim in this paper is to frame...

  11. 2009 Annual Report of China's Paper Industry

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    @@ Ⅰ.Production and Consumption of Paper & Board 1.The General Situation of 2009According to the survey made by China Paper Association,in 2009,there were about 3,700 paper & board manufacturers; their total production of paper & board was86.40 million tons,increased by 8.27% compared to 79.80million tons in 2008; the total paper & board consumption was 85.69 million tons,increased by 7.99% compared to 79.35 million tons in 2008;paper & board per capita consumption was 64 kg,increased 4 kg.

  12. 2007 Annual Report of China's Paper Industry

    Institute of Scientific and Technical Information of China (English)

    China Paper Association

    2008-01-01

    @@ 1.Production and consumption of paper and board 1. According to the survey made by China Paper Association,CPA, in 2007, there were about 3500 paper mills of China'spaper industry; their total output of paper & board was 73.50 million tons, increased by 13.08% compared with 65.00 mil-lion tons in 2006; the total paper & board consumption was72.90 million tons, increased by 10.45% compared with 66.00 million tons in 2006; paper & board per capita consumption reached 55 kg from 50 kg in 2006.

  13. 75 FR 43799 - Employee Contribution Elections and Contribution Allocations

    Science.gov (United States)

    2010-07-27

    ... Part 1600 Employee Contribution Elections and Contribution Allocations AGENCY: Federal Retirement...), which was established by the Federal Employees' Retirement System Act of 1986 (FERSA), Public Law 99-335...-79. The TSP is a tax-deferred retirement savings plan for Federal civilian employees and members...

  14. New criteria for the characterization of traditional East Asian papers.

    Science.gov (United States)

    Avataneo, Chiara; Sablier, Michel

    2017-01-01

    We report a pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS) method capable of analyzing traditional East Asian papers. The method proposed is based on rapid and easy single step Py-GC/MS analysis that can be carried out with a minimum amount of matter, in the few microgram range. Three reference papers manufactured from kozo (Broussonetia kazinoki Siebold & Zucc.), mitsumata (Edgeworthia chrysantha Lindl.), and gampi (Wikstroemia sikokiana Franch. & Sav.) with the traditional hand paper making processes were examined. The method allows discrimination between terpenic and steroid compounds, which were revealed as chemical markers of origin of the plant fibers. Each paper investigated was found to have characteristic pyrolysis fingerprints that were unique to the traditional handmade paper, demonstrating the potential for differentiation of these biochemical components of fiber plants on East Asian papers towards identification and conservation of cultural heritage. The investigation on Py-GC/MS was extended to liquid extraction followed by GC/MS analysis to characterize the biochemical components of fiber plants. The main contribution of this study is to provide molecular criteria for discriminating plant species used for traditional East Asian hand papermaking. Py-GC/MS complements efficiently microscope identification especially for adverse cases. A case study of archaeological Chinese paper painting artefacts was thereafter successfully investigated to address informative potential and efficiency of the criteria of identification on ancient and degraded East Asian paperworks.

  15. BOOK REVIEW: A Student's Guide to Einstein's Major Papers A Student's Guide to Einstein's Major Papers

    Science.gov (United States)

    Janssen, Michel

    2013-12-01

    The core of this volume is formed by four chapters (2-5) with detailed reconstructions of the arguments and derivations in four of Einstein's most important papers, the three main papers of his annus mirabilis 1905 (on the light quantum, Brownian motion, and special relativity) and his first systematic exposition of general relativity of 1916. The derivations are given in sufficient detail and in sufficiently modernized notation (without any serious distortion of the originals) for an undergraduate physics major to read and understand them with far less effort than it would take him or her to understand (English translations of) Einstein's original papers. Each of these four papers is accompanied by a detailed introduction, which covers the conceptual development of the relevant field prior to Einstein's contribution to it and corrects some of the myths surrounding these papers that still have not been fully eradicated among physicists. (One quibble: though Kennedy correctly points out that the goal of the light quantum paper was not to explain the photoelectric effect, it is also not quite right to say that 'it was written to explain the Wien region of blackbody radiation' (p. xv). Einstein used this explanatory feat as the central argument for his light quantum hypothesis.) These four chapters then are the most valuable part of the volume. They could be used, independently of one another, but preferably in conjunction with Einstein's original texts, in courses on quantum mechanics, statistical mechanics, electrodynamics, and general relativity, respectively, to add a historical component to such courses. As a historian of science embedded in a physics department who is regularly called upon to give guest lectures in such courses on the history of their subjects, I can highly recommend the volume for this purpose. However, I would not adopt this volume as (one of) the central text(s) for a course on the history of modern physics. For one thing, chapter 1, which in

  16. Printability of Synthetic Papers by Electrophotography

    Directory of Open Access Journals (Sweden)

    Rozália Szentgyörgyvölgyi

    2010-04-01

    Full Text Available This paper deals with the printability of synthetic papers by the electrophotography technique. Prints of cmyk colour fields from 20% to 100% raster tone values were printed on three types of synthetic papers (one film synthetic paper and two fiber synthetic papers. The investigation of the appearance included densitometric measurement of the cmyk prints. The results have shown differences in the optical density and optical tone value between cmyk prints made on various synthetic papers. The highest optical density and the increase of the optical tone value were observed on the film synthetic paper, where cmyk prints were more saturated. The highest abrasion resistance of cmyk prints was obtained from the fibre synthetic paper.

  17. Selected papers on analysis and differential equations

    CERN Document Server

    Nomizu, Katsumi

    2003-01-01

    This volume contains translations of papers that originally appeared in the Japanese journal, Sugaku. The papers range over a variety of topics, including nonlinear partial differential equations, C^*-algebras, and Schrödinger operators.

  18. Open Education. Introduction to selected papers

    Directory of Open Access Journals (Sweden)

    Inés Gil-Jaurena

    2017-06-01

    Full Text Available This issue of Open Praxis compiles selected papers presented at the Open Education Consortium Global Conference, held in Cape Town (South Africa on March 8-10, 2017. Additionaly, the Innovative Practice section includes three papers.

  19. Paper based microfluidic devices for environmental diagnostics

    CSIR Research Space (South Africa)

    Govindasamy, K

    2012-09-01

    Full Text Available such as elevated temperatures and mechanical stresses. Paper based microfluidic chips are patterned with micron sized hydrophobic barriers which penetrate the paper?s cross section. These barriers guide the capillary movement of fluids through the cellulose... visual or electrochemical signal, indicating whether the analyte is present in the sample. Although based on a similar operational principal as lateral flow technologies (such as home pregnancy tests), paper based microfluidics seeks to offer a more...

  20. Mathematical modelling of paper degradation in books

    OpenAIRE

    Nimmo, A J

    2015-01-01

    Paper cannot be prevented from degrading and does not necessarily degrade uniformly across its volume. It has been established that as paper degrades, VOCs (Volatile Organic Compounds) are produced. This body of work studies paper degradation with respect to the role VOCs play. The thesis investigates how a VOC a ecting the paper's acidity can in turn a ect the degradation rate and through modelling the VOC concentration pro le, the degradation pro le is found. To create the model from a chem...

  1. Remote Sensing Best Paper Award 2013

    OpenAIRE

    Prasad Thenkabail

    2013-01-01

    Remote Sensing has started to institute a “Best Paper” award to recognize the most outstanding papers in the area of remote sensing techniques, design and applications published in Remote Sensing. We are pleased to announce the first “Remote Sensing Best Paper Award” for 2013. Nominations were selected by the Editor-in-Chief and selected editorial board members from among all the papers published in 2009. Reviews and research papers were evaluated separately.

  2. Visualization According To Research Paper Keywords

    OpenAIRE

    Isenberg, Petra; Isenberg, Tobias; Sedlmair, Michael; Chen, Jian; Möller, Torsten

    2014-01-01

    To appear; International audience; We analyzed visualization paper keywords supplied for 4366 papers accepted to three main visualization conferences. We describe main keywords, topic areas, and 10-year historic trends from author-chosen keywords for papers published in the IEEE Visualization conference series (now called IEEE VIS) since 2004. Furthermore, we present the KeyVis Web application that allows visualization researchers to easily browse the 2600+ keywords used for IEEE VIS papers o...

  3. Guinea-Bissau; Poverty Reduction Strategy Paper

    OpenAIRE

    International Monetary Fund

    2007-01-01

    This paper presents an overview of the National Poverty Reduction Strategy Paper (NPRSP) for Guinea-Bissau. The paper discusses the phenomenon of poverty, its dimensions, extent, and distribution by category and region. It provides a background analysis of developments in poverty based on the diagnostic of past economic policies. The paper presents the priority goals in the fight against poverty by articulating a long-term and medium-term vision as well as strategic actions. The operational s...

  4. Integrating Electronics and Microfluidics on Paper.

    Science.gov (United States)

    Hamedi, Mahiar M; Ainla, Alar; Güder, Firat; Christodouleas, Dionysios C; Fernández-Abedul, M Teresa; Whitesides, George M

    2016-07-01

    Paper microfluidics and printed electronics have developed independently, and are incompatible in many aspects. Monolithic integration of microfluidics and electronics on paper is demonstrated. This integration makes it possible to print 2D and 3D fluidic, electrofluidic, and electrical components on paper, and to fabricate devices using them.

  5. Computers & Chemical Engineering: Best paper of 2009

    DEFF Research Database (Denmark)

    Venkatasubramanian, Venkat; Gani, Rafiqul

    2011-01-01

    The Editorial Advisory Board of the Journal has assessed the papers published in Volume 33 by means of a three stage process of nomination and balloting. We are pleased to announce that the 2009 Best Paper of the Year Award goes to J.M. Harrold and R.S. Parker for their paper entitled “Clinically...

  6. Demonstrating Fluorescence with Neon Paper and Plastic

    Science.gov (United States)

    Birriel, Jennifer J.; Roe, Clarissa

    2015-01-01

    Several papers in this journal have dealt with the fluorescence in orange neon plastic, olive oil, and soda. In each case, the fluorescent emission was excited by either green or violet-blue laser light. In this paper, we examine the fluorescent emission spectra of so-called neon colored papers and plastic clipboards available in department and…

  7. Paper Sludge Reuse in Lightweight Aggregates Manufacturing.

    Science.gov (United States)

    Chen, How-Ji; Hsueh, Ying-Chih; Peng, Ching-Fang; Tang, Chao-Wei

    2016-10-27

    The lightweight aggregates used by the civil engineering market are sintered at a high temperature, about 1200 °C. In times of high energy prices and regulation of carbon dioxide emissions, lightweight aggregate products of the high-temperature process in sales marketing are not readily accepted. This study developed a sintered-type paper sludge lightweight aggregate. In order to reduce energy consumption, substitution of some reservoir sediment clay in paper sludge substitutes is to be expected. The study used two types of paper sludge (green clay paper sludge and paper pulp sludge). The sintering temperature was reduced effectively as the green clay paper sludge was substituted for some of the reservoir sediment clay, and the optimum substitute ranges of green clay paper sludge were 10%-50%. The optimum substitute ranges of the paper pulp sludge were 10%-40%. Test results show that the properties of aggregates have a particle density of 0.66-1.69 g/cm³, a water absorption of 5%-30%, and a loss on ignition of 10%-43%. The loss on ignition of aggregate became greater with the increase in paper sludge content. This means that the calorific value provided by the paper sludge will increase as paper sludge content increases. Paper sludge can therefore be considered a good material to provide heat energy for sintering lightweight aggregate.

  8. 76 FR 171 - Paper Clips From China

    Science.gov (United States)

    2011-01-03

    ... COMMISSION Paper Clips From China AGENCY: United States International Trade Commission. ACTION: Institution of a five-year review concerning the antidumping duty order on paper clips from China. SUMMARY: The... on paper clips from China would be likely to lead to continuation or recurrence of material...

  9. Constructing a Rhombus through Paper Folding

    Science.gov (United States)

    Duatepe-Paksu, Asuman

    2017-01-01

    This paper presents an example of how paper folding can be used in a geometry class to support conceptual understanding. Specifically, it explains an activity that constructs a rhombus and explores its attributes by using paper folding. The steps of constructing a rhombus are described and some discussion questions are given to consolidate…

  10. 12 CFR 541.5 - Commercial paper.

    Science.gov (United States)

    2010-01-01

    ... 12 Banks and Banking 5 2010-01-01 2010-01-01 false Commercial paper. 541.5 Section 541.5 Banks and Banking OFFICE OF THRIFT SUPERVISION, DEPARTMENT OF THE TREASURY DEFINITIONS FOR REGULATIONS AFFECTING FEDERAL SAVINGS ASSOCIATIONS § 541.5 Commercial paper. The term commercial paper means any note, draft, or...

  11. 7 CFR 51.1240 - Paper ends.

    Science.gov (United States)

    2010-01-01

    ... 7 Agriculture 2 2010-01-01 2010-01-01 false Paper ends. 51.1240 Section 51.1240 Agriculture Regulations of the Department of Agriculture AGRICULTURAL MARKETING SERVICE (Standards, Inspections, Marketing... Standards for Cleaned Virginia Type Peanuts in the Shell Definitions § 51.1240 Paper ends. Paper ends means...

  12. Common mistakes in writing a scientific paper

    Directory of Open Access Journals (Sweden)

    Militon Frentiu

    2010-12-01

    Full Text Available As editors of Studia UBB Informatica we have noticed that many papers contains some frequent errors. The best way to change this situation, to improve the quality of Studia papers, is to underline these frequent errors. And also, to offer a guide for writing papers for the Studia UBB Informatica journal, which we have done.

  13. Misery Needs Company: The Group Paper.

    Science.gov (United States)

    Pomper, Marlene M.

    Many students consider the writing of papers to be a lonely, difficult, and even painful process. To enable these students to improve their essays and research papers, a teacher has used a collaborative method of writing called the group paper. This method encompasses the various stages of writing, from freewriting of first drafts through multiple…

  14. 49 CFR 174.24 - Shipping papers.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Shipping papers. 174.24 Section 174.24... Requirements § 174.24 Shipping papers. (a) A person may not accept a hazardous material for transportation or transport a hazardous material by rail unless that person receives a shipping paper prepared in...

  15. 49 CFR 177.817 - Shipping papers.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Shipping papers. 177.817 Section 177.817... Information and Regulations § 177.817 Shipping papers. (a) General requirements. A person may not accept a... received a shipping paper prepared in accordance with part 172 of this subchapter or the material...

  16. 49 CFR 176.24 - Shipping papers.

    Science.gov (United States)

    2010-10-01

    ... 49 Transportation 2 2010-10-01 2010-10-01 false Shipping papers. 176.24 Section 176.24... Requirements § 176.24 Shipping papers. (a) A person may not accept a hazardous material for transportation or transport a hazardous material by vessel unless that person has received a shipping paper prepared...

  17. Accountability: Papers from master theses 2009

    NARCIS (Netherlands)

    C.D. Knoops (Chris); J. Noeverman (Jan)

    2010-01-01

    textabstractLast year, we presented the book “Accountability 2008: papers from master theses”. The book contained eleven papers. Each paper was based on a thesis in the field of Accounting, Auditing and Control, on which these students received a Master’s degree in Economics & Business from the Eras

  18. 76 FR 42730 - Paper Clips From China

    Science.gov (United States)

    2011-07-19

    ... COMMISSION Paper Clips From China Determination On the basis of the record \\1\\ developed in the subject five... order on paper clips from China would be likely to lead to continuation or recurrence of material injury... Publication 4242 (July 2011), entitled Paper Clips from China: Investigation No. 731-TA-663 (Third Review)....

  19. Selected papers on analysis and differential equations

    CERN Document Server

    Society, American Mathematical

    2010-01-01

    This volume contains translations of papers that originally appeared in the Japanese journal Sūgaku. These papers range over a variety of topics in ordinary and partial differential equations, and in analysis. Many of them are survey papers presenting new results obtained in the last few years. This volume is suitable for graduate students and research mathematicians interested in analysis and differential equations.

  20. Demonstrating Fluorescence with Neon Paper and Plastic

    Science.gov (United States)

    Birriel, Jennifer J.; Roe, Clarissa

    2015-01-01

    Several papers in this journal have dealt with the fluorescence in orange neon plastic, olive oil, and soda. In each case, the fluorescent emission was excited by either green or violet-blue laser light. In this paper, we examine the fluorescent emission spectra of so-called neon colored papers and plastic clipboards available in department and…

  1. Focus on China's Paper Industry

    Institute of Scientific and Technical Information of China (English)

    2012-01-01

    In the English section of this issue, 〈China Paper Newsletter〉 will introduce" the Twelfth Five-Year Plan of China's Paper Industry"," 2011 Annual Report of China's Paper Industry", and news of projects.

  2. 75 FR 32659 - Contributed Property

    Science.gov (United States)

    2010-06-09

    ... Internal Revenue Service 26 CFR Part 1 RIN 1545-BF28 Contributed Property AGENCY: Internal Revenue Service... property to the partnership. In that regard, the anti- abuse rule of Sec. 1.701-2(b) provides that, if a... contribution of property to a partnership should be recast to avoid results that are inconsistent...

  3. Electronic Paper:Concept and Expectations

    Institute of Scientific and Technical Information of China (English)

    Makoto Omodani

    2004-01-01

    The expectations for electronic paper can be summarized as flexibility, readability, and multi-functionality. It focuses on the goal of readability. Paper-like readability should be accepted as the most important target of electronic paper. A concept of readable electronic paper is proposed, and its expected properties, style variations, applications, and various candidate technologies are summarized. As an indication of the realization of readability, an evaluation of user comfort when conducting reading tasks on paper and an LCD shows that free handling of the medium is an important factor in achieving excellent readability.

  4. Persistent paper: the myth of "going paperless".

    Science.gov (United States)

    Dykstra, Richard H; Ash, Joan S; Campbell, Emily; Sittig, Dean F; Guappone, Ken; Carpenter, James; Richardson, Joshua; Wright, Adam; McMullen, Carmit

    2009-11-14

    How does paper usage change following the introduction of Computerized Physician Order Entry and the Electronic Medical Record (EMR/CPOE)? To answer that question we analyzed data collected from fourteen sites across the U.S. We found paper in widespread use in all institutions we studied. Analysis revealed psychological, ergonomic, technological, and regulatory reasons for the persistence of paper in an electronic environment. Paper has unique attributes allowing it to fill gaps in information timeliness, availability, and reliability in pursuit of improved patient care. Creative uses have led to "better paper."

  5. Pen-and-Paper User Interfaces

    CERN Document Server

    Steimle, Jurgen

    2012-01-01

    Even at the beginning of the 21st century, we are far from becoming paperless. Pen and paper is still the only truly ubiquitous information processing technology. Pen-and-paper user interfaces bridge the gap between paper and the digital world. Rather than replacing paper with electronic media, they seamlessly integrate both worlds in a hybrid user interface. Classical paper documents become interactive. This opens up a huge field of novel computer applications at our workplaces and in our homes. This book provides readers with a broad and extensive overview of the field, so as to provide a fu

  6. Bacteria-powered battery on paper.

    Science.gov (United States)

    Fraiwan, Arwa; Choi, Seokheun

    2014-12-21

    Paper-based devices have recently emerged as simple and low-cost paradigms for fluid manipulation and analytical/clinical testing. However, there are significant challenges in developing paper-based devices at the system level, which contain integrated paper-based power sources. Here, we report a microfabricated paper-based bacteria-powered battery that is capable of generating power from microbial metabolism. The battery on paper showed a very short start-up time relative to conventional microbial fuel cells (MFCs); paper substrates eliminated the time traditional MFCs required to accumulate and acclimate bacteria on the anode. Only four batteries connected in series provided desired values of current and potential to power an LED for more than 30 minutes. The battery featured (i) a low-cost paper-based proton exchange membrane directly patterned on commercially available parchment paper and (ii) paper reservoirs for holding the anolyte and the catholyte for an extended period of time. Based on this concept, we also demonstrate the use of paper-based test platforms for the rapid characterization of electricity-generating bacteria. This paper-based microbial screening tool does not require external pumps/tubings and represents the most rapid test platform (<50 min) compared with the time needed by using traditional screening tools (up to 103 days) and even recently proposed MEMS arrays (< 2 days).

  7. Hygroscopic behaviour of paper and books

    DEFF Research Database (Denmark)

    Derluyn, Hannelore; Janssen, Hans; Diepens, Jan

    2007-01-01

    This study presents experimental analysis and numerical modeling of hygroscopic moisture buffering by paper and books. First, a literature review of moisture transport properties of paper is presented. Experimental work on two paper types includes SEM analysis of the paper structure, determination...... and not on the relative humidity. Books consist of several paper sheets with air layers between the sheets. To take the air layers into account, a parallel transport model is proposed to determine the effective moisture transport properties of books taking into account the air layers. The dynamic hygroscopic behavior...... of small book samples was measured. It is shown that, although the water vapor permeability of different paper types can be quite different, the effusivity of a book highly depends on the presence of the air layers and can therefore remain comparable for different paper types....

  8. Pulsed Laser Processing of Paper Materials

    Science.gov (United States)

    Schechtel, Florian; Reg, Yvonne; Zimmermann, Maik; Stocker, Thomas; Knorr, Fabian; Mann, Vincent; Roth, Stephan; Schmidt, Michael

    At present the trends in paper and packaging industries are the personalization of products and the use of novel high-tech materials. Laser processes as non-contact and flexible techniques seem to be the obvious choice to address those developments. In this paper we present a basic understanding of the occurring mechanisms of laser based engraving of different paper and paperboard materials, using a picosecond laser source at 1064 nm. The influences on the beam-paper-interaction of grammage, the composition of the paper matrix, as well as the paper inherent cellulose fibers were investigated. Here the ablation threshold of commercially available paper was determined and a matrix ablation effect under the 1064 nm radiation observed. These results were characterized and qualified mainly by means of laser scanning microscope (LSM) micrographs in combination with color-space analytics.

  9. Processing and Structure of Carbon Nanofiber Paper

    Directory of Open Access Journals (Sweden)

    Zhongfu Zhao

    2009-01-01

    Full Text Available A unique concept of making nanocomposites from carbon nanofiber paper was explored in this study. The essential element of this method was to design and manufacture carbon nanofiber paper with well-controlled and optimized network structure of carbon nanofibers. In this study, carbon nanofiber paper was prepared under various processing conditions, including different types of carbon nanofibers, solvents, dispersants, and acid treatment. The morphologies of carbon nanofibers within the nanofiber paper were characterized with scanning electron microscopy (SEM. In addition, the bulk densities of carbon nanofiber papers were measured. It was found that the densities and network structures of carbon nanofiber paper correlated to the dispersion quality of carbon nanofibers within the paper, which was significantly affected by papermaking process conditions.

  10. Identification of milestone papers through time-balanced network centrality

    CERN Document Server

    Mariani, Manuel Sebastian; Zhang, Yi-Cheng

    2016-01-01

    Citations between scientific papers and related bibliometric indices, such as the $h$-index for authors and the impact factor for journals, are being increasingly used -- often in controversial ways -- as quantitative tools for research evaluation. Yet, a fundamental research question remains still open: to which extent do quantitative metrics capture the significance of scientific works? We analyze the network of citations among the $449,935$ papers published by the American Physical Society (APS) journals between $1893$ and $2009$, and focus on the comparison of metrics built on the citation count with network-based metrics. We contrast five article-level metrics with respect to the rankings that they assign to a set of fundamental papers, called Milestone Letters, carefully selected by the APS editors for "making long-lived contributions to physics, either by announcing significant discoveries, or by initiating new areas of research". A new metric, which combines PageRank centrality with the explicit requi...

  11. Biomolecule immobilization techniques for bioactive paper fabrication.

    Science.gov (United States)

    Kong, Fanzhi; Hu, Yim Fun

    2012-04-01

    Research into paper-based sensors or functional materials that can perform analytical functions with active recognition capabilities is rapidly expanding, and significant research effort has been made into the design and fabrication of bioactive paper at the biosensor level to detect potential health hazards. A key step in the fabrication of bioactive paper is the design of the experimental and operational procedures for the immobilization of biomolecules such as antibodies, enzymes, phages, cells, proteins, synthetic polymers and DNA aptamers on a suitably prepared paper membrane. The immobilization methods are concisely categorized into physical absorption, bioactive ink entrapment, bioaffinity attachment and covalent chemical bonding immobilization. Each method has individual immobilization characteristics. Although every biomolecule-paper combination has to be optimized before use, the bioactive ink entrapment method is the most commonly used approach owing to its general applicability and biocompatibility. Currently, there are four common applications of bioactive paper: (1) paper-based bioassay or paper-based analytical devices for sample conditioning; (2) counterfeiting and countertempering in the packaging and construction industries; (3) pathogen detection for food and water quality monitoring; and (4) deactivation of pathogenic bacteria using antimicrobial paper. This article reviews and compares the different biomolecule immobilization techniques and discusses current trends. Current, emerging and future applications of bioactive paper are also discussed.

  12. Papers presented by nurses at scientific events in Turkey

    Directory of Open Access Journals (Sweden)

    Ülkü Yapucu Güneş

    2008-11-01

    Full Text Available This study, which originated from the observation that the rate of participation in scientific events by nurses working in the field as well as that of academician nurses had gradually increased, was a definitive, record-scanning study made with the objective of examining the papers presented by nurses at scientific meetings between 1985 and 2003. Nursing research has become an increasingly important factor in the efforts devoted to making nursing an academic profession. The development of nursing research in different countries has been influenced by various factors. While there is a long tradition of nursing research in some other countries, the history of nursing research in Turkey is shorter. The environment of this research was formed from papers included in books and summary booklets of scientific meetings in which nurses participated between 1985 and 2003. 2,843 papers, contained in 80 scientific activity books and summary booklets, formed the sampling of the research. When the year-to-year distribution of authors who presented papers was examined, it was found that while there was an increase in the proportion of papers presented by nurses alone, by nurses and academician nurses, or by nurses and members of other disciplines, there was a decrease in the proportion of papers submitted by academician nurses. The results of this study show that nurses have contributed to the process of professionalizing nursing and are accepted by other members of the health team.

  13. Streamflow modelling by remote sensing: a contribution to digital earth

    NARCIS (Netherlands)

    Tan, M.L.; Latif, A.B.; Pohl, C.; Duan, Z.

    2014-01-01

    Remote sensing contributes valuable information to streamflow estimates. This paper discusses its relevance to the digital earth concept. The authors categorize the role of remote sensing in streamflow modelling and estimation. This paper emphasizes the applications and challenges of satellite-based

  14. Contribution factor of wood properties of three poplar clones to strength of laminated veneer lumber

    Science.gov (United States)

    Fucheng Bao; Feng Fu; Elvin Choong; Chung-Yun Hse

    2001-01-01

    The term "Contribution Factor" (c.) was introduced in this paper to indicate the contribution ratio of solid wood properties to laminated veneer lumber (LVL) strength. Three poplar (Populus sp.) clones were studied, and the results showed that poplar with good solid wood properties has high Contribution Factor. The average Contribution...

  15. Ethnographic Contributions to Method Development

    DEFF Research Database (Denmark)

    Leander, Anna

    2014-01-01

    Program paper title: The Reversal of Value Neutrality: Research Ethics in Critical Approaches to Security......Program paper title: The Reversal of Value Neutrality: Research Ethics in Critical Approaches to Security...

  16. Contribution of controlling to business efficiency

    Directory of Open Access Journals (Sweden)

    Todorović-Dudić Aleksandra

    2017-01-01

    Full Text Available The authors of the paper analyse the contribution of controlling to enterprise efficiency. Controlling is an approach that helps companies focus on creating value and driving value creation, quality increase and cost reduction. On the basis of a representative sample of industrial-sector companies in Serbia, the authors conducted a multivariate analysis of variance (MANOVA, discriminant analyses and other parametric procedures and methods. Univariate procedures applied are the Roy's test, Pearson's contingency coefficient (x and the multiple correlation coefficient (R. As a result, the difference in controlling among enterprises relating to identification of controlling contribution to enterprise efficiency is determined. The existence of a boundary is confirmed. As a clear boundary between controlling processes in enterprises is defined, their characteristics are also determined.

  17. Universal corner contributions to entanglement negativity

    CERN Document Server

    Kim, Keun-Young; Pang, Da-Wei

    2016-01-01

    It has been realised that corners in entangling surfaces can induce new universal contributions to the entanglement entropy and R\\'enyi entropy. In this paper we study universal corner contributions to entanglement negativity in three- and four-dimensional CFTs using both field theory and holographic techniques. We focus on the quantity $\\chi$ defined by the ratio of the universal part of the entanglement negativity over that of the entanglement entropy, which may characterise the amount of distillable entanglement. We find that for most of the examples $\\chi$ takes bigger values for singular entangling regions, which may suggest increase in distillable entanglement. However, there also exist counterexamples where distillable entanglement decreases for singular surfaces. We also explore the behaviour of $\\chi$ as the coupling varies and observe that for singular entangling surfaces, the amount of distillable entanglement is mostly largest for free theories, while counterexample exists for free Dirac fermion i...

  18. Contributions of Literature to Social Psychology

    Directory of Open Access Journals (Sweden)

    Anastasio Ovejero

    2012-11-01

    Full Text Available There are two main kind of psychology: a intuitive psychology, and an academic and professional psychology. These two psychologies are different, but they can make important reciprocals contributions. And the best of the intuitive psychology, that in my opinion is in the literature and overall in the romance, can be very useful for professional psychologists. The main end of this paper is to show how the social psychologists can learn from the intuitive psychology of the great romances. This contribution of the romance to the social psychology is, at least, at these two levels. At the level of construction of the subjectivity and the modern subject and the, therefore, of the psychology’s arise, and at the level of some concrete subjects studied by the psychologists (romantic love, jealousy, infidelity, compunction, emotions, vengeance, human relations…

  19. Contribution of Latin America to pharmacovigilance.

    Science.gov (United States)

    González, Juan Camilo; Arango, Victoria E; Einarson, Thomas R

    2006-01-01

    Pharmacovigilance activities have been ongoing for 4 decades. However, little is known (especially outside of the area) about the contribution of Latin America to this field. To review and quantify the published literature on pharmacovigilance in Latin American countries. We searched electronic databases including MEDLINE (1966-2004), EMBASE (1980-2004), International Pharmaceutical Abstracts (1970-2004), Toxline (1992-2004), Literatura Latino-Americana e do Caribe em Ciências da Saúde (1982-2004), Sistema de Información Esencial en Terapéutica y Salud (1980-2004), and the Pan American Health Organization Web site (1970-2004) for articles on pharmacovigilance or adverse drug reactions in any of the 19 major Latin American countries. Papers were retrieved and categorized according to content and country of origin by 2 independent reviewers. There were 195 usable articles from 13 countries. Fifty-one of the papers retrieved dealt with pharmacovigilance centers (15 national centers, 10 hospitals, 26 other), 55 covered pharmacovigilance itself (21 theoretical papers, 9 with description of models, 25 educational papers), and 89 were pharmacoepidemiologic studies of adverse drug reactions (69 case reports, 13 observational cohorts, 2 cohort studies, 1 randomized clinical trial, 4 clinical papers on adverse reaction management). Studies have increased exponentially since 1980. Five countries (Argentina, Brazil, Chile, Costa Rica, Venezuela) published reports from national centers. No studies were found from 6 countries: Dominican Republic, El Salvador, Honduras, Nicaragua, Paraguay, or Uruguay. Most studied categories were antiinfectives and drugs affecting the central nervous system, cardiovascular system, and musculoskeletal system. Contributions of Latin American countries to the field of pharmacovigilence have been remarkable, considering the constraints on these countries. A need exists for an increased number of formal pharmacovigilance studies and research

  20. WATER RESISTANCE OF RECYCLED PAPER PANEL

    Directory of Open Access Journals (Sweden)

    Alexander Rani Suryandono

    2017-06-01

    Alice Wisler (2015 Facts about Recycling Paper. http://greenliving.lovetoknow.com/Facts_About_Recycling_Paper. Accessed 2 April 2016 Clay Miller (2011 5 Benefits of Recycling Paper. http://www.ways2gogreenblog.com/2011/09/28/5-benefits-of-recycling-paper/. Accessed 10 May 2016 Hari Goyal (2015 Grades of Paper. http://www.paperonweb.com/grade.htm. Accessed 2 April 2016 Hari Goyal (2015 Properties of Paper. http://www.paperonweb.com/paperpro.htm. Accessed 2 April 2016 Kathryn Sukalich (2016 Everything You Need to Know about Paper Recycling. http://earth911.com/business-policy/business/paper-recycling-details-basics/. Accessed 15 July 2016 [U1] Larry West (2015 Why Recycle Paper. http://environment.about.com/od/recycling/a/The-Benefits-Of-Paper-Recycling-Why-Recycle-Paper.htm. Accesed 15 June 2016 Marie-Luise Blue (2008 The Advantages of Recycling Paper. http://education.seattlepi.com/advantages-recycling-paper-3440.html. Accessed 15 June 2016 Nina Spitzer (2009 http://www.sheknows.com/home-and-gardening/articles/810025/the-impact-of-disposable-coffee-cups-on-the-environment. Accessed 15 June 2016 Radio New Zealand (2010 Iwi not Giving Up Fight against Tasman Mill Discharges. http://www.radionz.co.nz/news/regional/64521/iwi-not-giving-up-fight-against-tasman-mill-discharges. Accessed 15 July 2016 Rick LeBlanc (2016 Paper Recycling Facts, Figures and Information Sources. https://www.thebalance.com/paper-recycling-facts-figures-and-information-sources-2877868?_ga=1.192832942.544061388.1477446686. Accesed 2 April 2016 Robinson Meyer (2016 Will More Newspapers Go Nonprofit? http://www.theatlantic.com/technology/archive/2016/01/newspapers-philadelphia-inquirer-daily-news-nonprofit-lol-taxes/423960/. Accessed 3 August 2016 School of Engineering at Darthmouth (2010 Forest and Paper Industry. http://engineering.dartmouth.edu/~d30345d/courses/engs171/Paper.pdf. Accessed 2 April 2016 T. Subramani, V. Angappan. (2015. Experimental Investigation of Papercrete Concrete