ERIC Educational Resources Information Center
Landy, David; Silbert, Noah; Goldin, Aleah
2013-01-01
Despite their importance in public discourse, numbers in the range of 1 million to 1 trillion are notoriously difficult to understand. We examine magnitude estimation by adult Americans when placing large numbers on a number line and when qualitatively evaluating descriptions of imaginary geopolitical scenarios. Prior theoretical conceptions…
Numbers Defy the Law of Large Numbers
ERIC Educational Resources Information Center
Falk, Ruma; Lann, Avital Lavie
2015-01-01
As the number of independent tosses of a fair coin grows, the rates of heads and tails tend to equality. This is misinterpreted by many students as being true also for the absolute numbers of the two outcomes, which, conversely, depart unboundedly from each other in the process. Eradicating that misconception, as by coin-tossing experiments,…
Insights into Our Understandings of Large Numbers
ERIC Educational Resources Information Center
Kastberg, Signe E.; Walker, Vicki
2008-01-01
This article explores prospective teachers' understandings of one million to gain insights into the development of adult understanding of large numbers. Themes in the prospective teachers' work included number associated with a quantity of objects, number as an abstraction, and additive and multiplicative approaches. The authors suggest that the…
Reading the World through Very Large Numbers
ERIC Educational Resources Information Center
Greer, Brian; Mukhopadhyay, Swapna
2010-01-01
One original, and continuing, source of interest in large numbers is observation of the natural world, such as trying to count the stars on a clear night or contemplation of the number of grains of sand on the seashore. Indeed, a search of the internet quickly reveals many discussions of the relative numbers of stars and grains of sand. Big…
Small and large number discrimination in guppies.
Piffer, Laura; Agrillo, Christian; Hyde, Daniel C
2012-03-01
Non-verbal numerical behavior in human infants, human adults, and non-human primates appears to be rooted in two distinct mechanisms: a precise system for tracking and comparing small numbers of items simultaneously (up to 3 or 4 items) and an approximate system for estimating numerical magnitude of a group of objects. The most striking evidence that these two mechanisms are distinct comes from the apparent inability of young human infants and non-human primates to compare quantites across the small (<3 or 4)/large (>4) number boundary. We ask whether this distinction is present in lower animal species more distantly related to humans, guppies (Poecilia reticulata). We found that, like human infants and non-human primates, fish succeed at comparisons between large numbers only (5 vs. 10), succeed at comparisons between small numbers only (3 vs. 4), but systematically fail at comparisons that closely span the small/large boundary (3 vs. 5). Furthermore, increasing the distance between the small and large number resulted in successful discriminations (3 vs. 6, 3 vs. 7, and 3 vs. 9). This pattern of successes and failures is similar to those observed in human infants and non-human primates to suggest that the two systems are present and functionally distinct across a wide variety of animal species. PMID:21909934
Tutoring Large Numbers: An Unmet Challenge
ERIC Educational Resources Information Center
Lentell, Helen; O'Rourke, Jennifer
2004-01-01
Open and distance learning (ODL) is increasingly being regarded as a viable policy option for developing countries with limited educational resources for buildings, books and trained teachers, seeking to increase accessibility for large numbers of learners in education and training opportunities. Advocates of ODL as an appropriate solution to…
Thermocapillary bubble migration for large Marangoni Numbers
NASA Technical Reports Server (NTRS)
Balasubramaniam, R.
1987-01-01
The thermocapillary motion of spherical bubbles present in an unbounded liquid with a linear temperature distribution, when the Reynolds number and the Marangoni number are large is analyzed. Previous calculations of the terminal velocity performed for this parametric range did not take into complete consideration the thermal boundary layer present near the surface of the bubble. A scaling analysis is presented for this problem. The thermal boundary layer is analyzed by an integral method. The resulting terminal velocity is lower than the one previously calculated, though it is of the same order of magnitude.
Large numbers hypothesis. I - Classical formalism
NASA Technical Reports Server (NTRS)
Adams, P. J.
1982-01-01
A self-consistent formulation of physics at the classical level embodying Dirac's large numbers hypothesis (LNH) is developed based on units covariance. A scalar 'field' phi(x) is introduced and some fundamental results are derived from the resultant equations. Some unusual properties of phi are noted such as the fact that phi cannot be the correspondence limit of a normal quantum scalar field.
Large numbers hypothesis. II - Electromagnetic radiation
NASA Technical Reports Server (NTRS)
Adams, P. J.
1983-01-01
This paper develops the theory of electromagnetic radiation in the units covariant formalism incorporating Dirac's large numbers hypothesis (LNH). A direct field-to-particle technique is used to obtain the photon propagation equation which explicitly involves the photon replication rate. This replication rate is fixed uniquely by requiring that the form of a free-photon distribution function be preserved, as required by the 2.7 K cosmic radiation. One finds that with this particular photon replication rate the units covariant formalism developed in Paper I actually predicts that the ratio of photon number to proton number in the universe varies as t to the 1/4, precisely in accord with LNH. The cosmological red-shift law is also derived and it is shown to differ considerably from the standard form of (nu)(R) - const.
Forecasting distribution of numbers of large fires
Eidenshink, Jeffery C.; Preisler, Haiganoush K.; Howard, Stephen; Burgan, Robert E.
2014-01-01
Systems to estimate forest fire potential commonly utilize one or more indexes that relate to expected fire behavior; however they indicate neither the chance that a large fire will occur, nor the expected number of large fires. That is, they do not quantify the probabilistic nature of fire danger. In this work we use large fire occurrence information from the Monitoring Trends in Burn Severity project, and satellite and surface observations of fuel conditions in the form of the Fire Potential Index, to estimate two aspects of fire danger: 1) the probability that a 1 acre ignition will result in a 100+ acre fire, and 2) the probabilities of having at least 1, 2, 3, or 4 large fires within a Predictive Services Area in the forthcoming week. These statistical processes are the main thrust of the paper and are used to produce two daily national forecasts that are available from the U.S. Geological Survey, Earth Resources Observation and Science Center and via the Wildland Fire Assessment System. A validation study of our forecasts for the 2013 fire season demonstrated good agreement between observed and forecasted values.
Modified large number theory with constant G
Recami, E.
1983-03-01
The inspiring ''numerology'' uncovered by Dirac, Eddington, Weyl, et al. can be explained and derived when it is slightly modified so to connect the ''gravitational world'' (cosmos) with the ''strong world'' (hadron), rather than with the electromagnetic one. The aim of this note is to show the following. In the present approach to the ''Large Number Theory,'' cosmos and hadrons are considered to be (finite) similar systems, so that the ratio R-bar/r-bar of the cosmos typical length R-bar to the hadron typical length r-bar is constant in time (for instance, if both cosmos and hadrons undergo an expansion/contraction cycle: according to the ''cyclical big-bang'' hypothesis: then R-bar and r-bar can be chosen to be the maximum radii, or the average radii). As a consequence, then gravitational constant G results to be independent of time. The present note is based on work done in collaboration with P.Caldirola, G. D. Maccarrone, and M. Pavsic.
Large Rossby number flows in Cozumel Channel
NASA Astrophysics Data System (ADS)
Ochoa, J.; Candela, J.; Sheinbaum, J.; Badan, A.
2003-04-01
The Caribbean Current flows to the west impinging the Yucatan coast south of Cozumel Island, then, most of its flow turns north, surrounds the island and continues towards the Yucatan Straits. About 4 Sv in the mean pass between the Yucatan coast and the Cozumel Island; through the Cozumel Channel, where subinertial currents exhibit large ageostrophic fluctuations [Chavez et. al. (2003)]. This channel is about 18 km wide, 50 km long, 400 m deep, and 70 km southwest of the Yucatan Straits. The curvature and latitude of the Caribbean Current on its approach to the Yucatan coast vary significantly. Observations with two upward-looking ADCPs, 8.6 km from each other, closely aligned with the mean current at the channel's axis and entrance, allow robust estimations of the current speed (U), direction and curvature (|R|-1). A signed Rossby number (Uf-1R-1), where f is the Coriolis parameter, is readily available as a function of time. The positive/negative curvature is defined by the cyclonic/anticyclonic turn. The currents observations along with pressure measurements at both sides of the channel produce evidence that favor the bend of the current as the cause of the ageostrophic fluctuations. Another possible cause for the ageostrophic fluctuations is the passage of eddies within the channel. We test the gradient wind balance between the currents and pressure observations. A very low frequency component on the seasonal time scale and high frequency fluctuations (superinercial) do not adjust to this balance, only the intermediate frequency variations show a clear equilibrium of centripetal (i.e. due to curvature) plus Coriolis accelerations against the pressure gradient perpendicular to the velocity. The conjecture is that the ageostrophic fluctuations occur when the bend and approach of the Caribbean Current is just south of Cozumel Island, thus influencing all its entrance. When the current impinges the coast further south, the flow, with a longer path to transit
Applications of species accumulation curves in large-scale biological data analysis
Deng, Chao; Daley, Timothy; Smith, Andrew D
2016-01-01
The species accumulation curve, or collector’s curve, of a population gives the expected number of observed species or distinct classes as a function of sampling effort. Species accumulation curves allow researchers to assess and compare diversity across populations or to evaluate the benefits of additional sampling. Traditional applications have focused on ecological populations but emerging large-scale applications, for example in DNA sequencing, are orders of magnitude larger and present new challenges. We developed a method to estimate accumulation curves for predicting the complexity of DNA sequencing libraries. This method uses rational function approximations to a classical non-parametric empirical Bayes estimator due to Good and Toulmin [Biometrika, 1956, 43, 45–63]. Here we demonstrate how the same approach can be highly effective in other large-scale applications involving biological data sets. These include estimating microbial species richness, immune repertoire size, and k-mer diversity for genome assembly applications. We show how the method can be modified to address populations containing an effectively infinite number of species where saturation cannot practically be attained. We also introduce a flexible suite of tools implemented as an R package that make these methods broadly accessible. PMID:27252899
Accumulation-rate history at Siple Dome, West Antarctica, using bubble number-density
NASA Astrophysics Data System (ADS)
Spencer, M.; Dennison, A.; Alley, R. B.; Fitzpatrick, J. J.; Fegyveresi, J. M.
2012-12-01
Past allowable accumulation rate/temperature combinations at Siple Dome, West Antarctica, are estimated from the measured number-density of bubbles in ice core samples. Mass density increase and grain growth in polar firn both are controlled by temperature and accumulation rate, and their integrated effects are recorded in the number-density of bubbles as the firn changes to ice [1]. Accumulation-rate estimates from measured bubble number-density and additional constraints from numerical modeling of firn densification at Siple Dome are consistent with 1-D ice-flow model results that have little change in the thickness of the ice sheet in the central Ross Embayment of West Antarctica since the last glacial maximum [2]. Using methods developed to analyze late-Holocene bubble number-density samples from the West Antarctic Ice Sheet Divide Ice Core Project [3], Siple Dome bubble number-densities show an early-Holocene high in accumulation rate followed by an approximately 10% reduction in accumulation rate between 11.33 ka and 1.863 ka. [1] Spencer, M.K., R.B. Alley and J.J. Fitzpatrick. Developing a bubble number-density paleoclimatic indicator for glacier ice, J. Glaciol. 52(178), 358-364 (2006). [2] E.D. Waddington et al., Decoding the dipstick: thickness of Siple Dome, West Antarctica, at the last glacial maximum, Geology 33(4), 281-284 (2005). [3] J.M. Fegyveresi, et al., Late-Holocene climate evolution at the WAIS Divide site, West Antarctica: bubble number-density estimates, J. Glaciol., 57(204) , 629 - 638 (2011).
The Intuitiveness of the Law of Large Numbers
ERIC Educational Resources Information Center
Lem, Stephanie
2015-01-01
In this paper two studies are reported in which two contrasting claims concerning the intuitiveness of the law of large numbers are investigated. While Sedlmeier and Gigerenzer ("J Behav Decis Mak" 10:33-51, 1997) claim that people have an intuition that conforms to the law of large numbers, but that they can only employ this intuition…
Thermocapillary Bubble Migration: Thermal Boundary Layers for Large Marangoni Numbers
NASA Technical Reports Server (NTRS)
Balasubramaniam, R.; Subramanian, R. S.
1996-01-01
The migration of an isolated gas bubble in an immiscible liquid possessing a temperature gradient is analyzed in the absence of gravity. The driving force for the bubble motion is the shear stress at the interface which is a consequence of the temperature dependence of the surface tension. The analysis is performed under conditions for which the Marangoni number is large, i.e. energy is transferred predominantly by convection. Velocity fields in the limit of both small and large Reynolds numbers are used. The thermal problem is treated by standard boundary layer theory. The outer temperature field is obtained in the vicinity of the bubble. A similarity solution is obtained for the inner temperature field. For both small and large Reynolds numbers, the asymptotic values of the scaled migration velocity of the bubble in the limit of large Marangoni numbers are calculated. The results show that the migration velocity has the same scaling for both low and large Reynolds numbers, but with a different coefficient. Higher order thermal boundary layers are analyzed for the large Reynolds number flow field and the higher order corrections to the migration velocity are obtained. Results are also presented for the momentum boundary layer and the thermal wake behind the bubble, for large Reynolds number conditions.
Hyde, Daniel C; Spelke, Elizabeth S
2009-06-01
Behavioral and brain imaging research indicates that human infants, humans adults, and many nonhuman animals represent large nonsymbolic numbers approximately, discriminating between sets with a ratio limit on accuracy. Some behavioral evidence, especially with human infants, suggests that these representations differ from representations of small numbers of objects. To investigate neural signatures of this distinction, event-related potentials were recorded as adult humans passively viewed the sequential presentation of dot arrays in an adaptation paradigm. In two studies, subjects viewed successive arrays of a single number of dots interspersed with test arrays presenting the same or a different number; numerical range (small numerical quantities 1-3 vs. large numerical quantities 8-24) and ratio difference varied across blocks as continuous variables were controlled. An early-evoked component (N1), observed over widespread posterior scalp locations, was modulated by absolute number with small, but not large, number arrays. In contrast, a later component (P2p), observed over the same scalp locations, was modulated by the ratio difference between arrays for large, but not small, numbers. Despite many years of experience with symbolic systems that apply equally to all numbers, adults spontaneously process small and large numbers differently. They appear to treat small-number arrays as individual objects to be tracked through space and time, and large-number arrays as cardinal values to be compared and manipulated. PMID:18752403
Towards large-Chern-number topological phases by periodic quenching
NASA Astrophysics Data System (ADS)
Xiong, Tian-Shi; Gong, Jiangbin; An, Jun-Hong
2016-05-01
Topological phases with large Chern numbers have important implications. They were previously predicted to exist by considering fabricated long-range interactions or multilayered materials. Stimulated by recent wide interests in Floquet topological phases, here we propose a scheme to engineer large-Chern-number phases with ease by periodic quenching. Using a two-band system as an example, we theoretically show how a variety of topological phases with widely tunable Chern numbers can be generated by periodic quenching between two simple Hamiltonians that otherwise give low Chern numbers. The obtained large Chern numbers are explained through the emergence of multiple Dirac cones in the Floquet spectra. The transition lines between different topological phases in the two-band model are also explicitly found, thus establishing a class of easily solvable but very rich systems useful for further understandings and applications of topological phases in periodically driven systems.
NASA Astrophysics Data System (ADS)
Kupavskii, A. B.
2014-02-01
We study distance graphs with exponentially large chromatic numbers and without k-cliques, that is, complete subgraphs of size k. Explicit constructions of such graphs use vectors in the integer lattice. For a large class of graphs we find a sharp threshold for containing a k-clique. This enables us to improve the lower bounds for the maximum of the chromatic numbers of such graphs. We give a new probabilistic approach to the construction of distance graphs without k-cliques, and this yields better lower bounds for the maximum of the chromatic numbers for large k.
Experimental Observation of Large Chern Numbers in Photonic Crystals.
Skirlo, Scott A; Lu, Ling; Igarashi, Yuichi; Yan, Qinghui; Joannopoulos, John; Soljačić, Marin
2015-12-18
Despite great interest in the quantum anomalous Hall phase and its analogs, all experimental studies in electronic and bosonic systems have been limited to a Chern number of one. Here, we perform microwave transmission measurements in the bulk and at the edge of ferrimagnetic photonic crystals. Band gaps with large Chern numbers of 2, 3, and 4 are present in the experimental results, which show excellent agreement with theory. We measure the mode profiles and Fourier transform them to produce dispersion relations of the edge modes, whose number and direction match our Chern number calculations. PMID:26722920
Large eddy breakup devices as low Reynolds number airfoils
NASA Technical Reports Server (NTRS)
Anders, John B.
1986-01-01
Turbulent drag reduction downstream of large-eddy breakup (LEBU) devices is analyzed from the viewpoint of low-Reynolds number airfoil aerodynamics. It is argued that the variability of results between different research labs is primarily due to low Reynolds number 'phenomena' associated with unsteady separation/transition of the LEBU device boundary layer. LEBU drag reduction is shown to be an extremely sensitive function of device microgeometry at the low Reynolds numbers of all current investigations, and by analogy with conventional low-Reynolds number airfoil testing, the conclusion is drawn that the full potential for LEBU drag reduction must be explored at chord Reynolds numbers of 300,000 and above.
The factorization of large composite numbers on the MPP
NASA Technical Reports Server (NTRS)
Mckurdy, Kathy J.; Wunderlich, Marvin C.
1987-01-01
The continued fraction method for factoring large integers (CFRAC) was an ideal algorithm to be implemented on a massively parallel computer such as the Massively Parallel Processor (MPP). After much effort, the first 60 digit number was factored on the MPP using about 6 1/2 hours of array time. Although this result added about 10 digits to the size number that could be factored using CFRAC on a serial machine, it was already badly beaten by the implementation of Davis and Holdridge on the CRAY-1 using the quadratic sieve, an algorithm which is clearly superior to CFRAC for large numbers. An algorithm is illustrated which is ideally suited to the single instruction multiple data (SIMD) massively parallel architecture and some of the modifications which were needed in order to make the parallel implementation effective and efficient are described.
Complex networks with large numbers of labelable attractors
NASA Astrophysics Data System (ADS)
Mi, Yuanyuan; Zhang, Lisheng; Huang, Xiaodong; Qian, Yu; Hu, Gang; Liao, Xuhong
2011-09-01
Information storage in many functional subsystems of the brain is regarded by theoretical neuroscientists to be related to attractors of neural networks. The number of attractors is large and each attractor can be temporarily represented or suppressed easily by corresponding external stimulus. In this letter, we discover that complex networks consisting of excitable nodes have similar fascinating properties of coexistence of large numbers of oscillatory attractors, most of which can be labeled with a few nodes. According to a simple labeling rule, different attractors can be identified and the number of labelable attractors can be predicted from the analysis of network topology. With the cues of the labeling association, these attractors can be conveniently retrieved or suppressed on purpose.
Multimode one-way waveguides of large Chern numbers.
Skirlo, Scott A; Lu, Ling; Soljačić, Marin
2014-09-12
Current experimental realizations of the quantum anomalous Hall phase in both electronic and photonic systems have been limited to a Chern number of one. In photonics, this corresponds to a single-mode one-way edge waveguide. Here, we predict quantum anomalous Hall phases in photonic crystals with large Chern numbers of 2, 3, and 4. These new topological phases were found by simultaneously gapping multiple Dirac and quadratic points. We demonstrate a continuously tunable power splitter as a possible application of multimode one-way waveguides. All our findings are readily realizable at microwave frequencies. PMID:25259982
ERIC Educational Resources Information Center
Hyde, Daniel C.; Spelke, Elizabeth S.
2009-01-01
Behavioral and brain imaging research indicates that human infants, humans adults, and many nonhuman animals represent large nonsymbolic numbers approximately, discriminating between sets with a ratio limit on accuracy. Some behavioral evidence, especially with human infants, suggests that these representations differ from representations of small…
Nonlinear instability of elementary stratified flows at large Richardson number.
Majda, Andrew J.; Shefter, Michael G.
2000-03-01
Elementary stably stratified flows with linear instability at all large Richardson numbers have been introduced recently by the authors [J. Fluid Mech. 376, 319-350 (1998)]. These elementary stratified flows have spatially constant but time varying gradients for velocity and density. Here the nonlinear stability of such flows in two space dimensions is studied through a combination of numerical simulations and theory. The elementary flows that are linearly unstable at large Richardson numbers are purely vortical flows; here it is established that from random initial data, linearized instability spontaneously generates local shears on buoyancy time scales near a specific angle of inclination that nonlinearly saturates into localized regions of strong mixing with density overturning resembling Kelvin-Helmholtz instability. It is also established here that the phase of these unstable waves does not satisfy the dispersion relation of linear gravity waves. The vortical flows are one family of stably stratified flows with uniform shear layers at the other extreme and elementary stably stratified flows with a mixture of vorticity and strain exhibiting behavior between these two extremes. The concept of effective shear is introduced for these general elementary flows; for each large Richardson number there is a critical effective shear with strong nonlinear instability, density overturning, and mixing for elementary flows with effective shear below this critical value. The analysis is facilitated by rewriting the equations for nonlinear perturbations in vorticity-stream form in a mean Lagrangian reference frame. (c) 2000 American Institute of Physics. PMID:12779359
Lepton number violation in theories with a large number of standard model copies
Kovalenko, Sergey; Schmidt, Ivan; Paes, Heinrich
2011-03-01
We examine lepton number violation (LNV) in theories with a saturated black hole bound on a large number of species. Such theories have been advocated recently as a possible solution to the hierarchy problem and an explanation of the smallness of neutrino masses. On the other hand, the violation of the lepton number can be a potential phenomenological problem of this N-copy extension of the standard model as due to the low quantum gravity scale black holes may induce TeV scale LNV operators generating unacceptably large rates of LNV processes. We show, however, that this issue can be avoided by introducing a spontaneously broken U{sub 1(B-L)}. Then, due to the existence of a specific compensation mechanism between contributions of different Majorana neutrino states, LNV processes in the standard model copy become extremely suppressed with rates far beyond experimental reach.
Dirac cosmology. [large dimensionless numbers relation to universe age
NASA Technical Reports Server (NTRS)
Canuto, V.; Lodenquai, J.
1977-01-01
The large numbers hypothesis (LNH) linking the magnitude of large dimensionless ratios in physics (on the order of 10 to the 40th power) to cosmic time is examined. The LNH is checked against evidence on 3K background radiation of the universe and the (log N, log S)-relation for radio galaxies. Earlier criticisms of LNH by Gamow and Teller are examined, and alternative hypotheses put forth by Dicke and Carter (1974) are discussed. The discussion covers: continuous (additive or multiplicative) creation of matter, the Einstein metric and the atomic metric, and general cosmological and local astronomical implications of LNH. LNH is also viewed in relation to solar evolution and pulsar physics.
Improving CASINO performance for models with large number of electrons
Anton, L; Alfe, D; Hood, R Q; Tanqueray, D
2009-05-13
Quantum Monte Carlo calculations have at their core algorithms based on statistical ensembles of multidimensional random walkers which are straightforward to use on parallel computers. Nevertheless some computations have reached the limit of the memory resources for models with more than 1000 electrons because of the need to store a large amount of electronic orbitals related data. Besides that, for systems with large number of electrons, it is interesting to study if the evolution of one configuration of random walkers can be done faster in parallel. We present a comparative study of two ways to solve these problems: (1) distributed orbital data done with MPI or Unix inter-process communication tools, (2) second level parallelism for configuration computation.
From the Law of Large Numbers to Large Deviation Theory in Statistical Physics: An Introduction
NASA Astrophysics Data System (ADS)
Cecconi, Fabio; Cencini, Massimo; Puglisi, Andrea; Vergni, Davide; Vulpiani, Angelo
This contribution aims at introducing the topics of this book. We start with a brief historical excursion on the developments from the law of large numbers to the central limit theorem and large deviations theory. The same topics are then presented using the language of probability theory. Finally, some applications of large deviations theory in physics are briefly discussed through examples taken from statistical mechanics, dynamical and disordered systems.
Automatic trajectory measurement of large numbers of crowded objects
NASA Astrophysics Data System (ADS)
Li, Hui; Liu, Ye; Chen, Yan Qiu
2013-06-01
Complex motion patterns of natural systems, such as fish schools, bird flocks, and cell groups, have attracted great attention from scientists for years. Trajectory measurement of individuals is vital for quantitative and high-throughput study of their collective behaviors. However, such data are rare mainly due to the challenges of detection and tracking of large numbers of objects with similar visual features and frequent occlusions. We present an automatic and effective framework to measure trajectories of large numbers of crowded oval-shaped objects, such as fish and cells. We first use a novel dual ellipse locator to detect the coarse position of each individual and then propose a variance minimization active contour method to obtain the optimal segmentation results. For tracking, cost matrix of assignment between consecutive frames is trainable via a random forest classifier with many spatial, texture, and shape features. The optimal trajectories are found for the whole image sequence by solving two linear assignment problems. We evaluate the proposed method on many challenging data sets.
Electrohydrodynamic deformation of drops and bubbles at large Reynolds numbers
NASA Astrophysics Data System (ADS)
Schnitzer, Ory
2015-11-01
In Taylor's theory of electrohydrodynamic drop deformation by a uniform electric field, inertia is neglected at the outset, resulting in fluid velocities that scale with E2, E being the applied-field magnitude. When considering strong fields and low viscosity fluids, the Reynolds number predicted by this scaling may actually become large, suggesting the need for a complementary large-Reynolds-number analysis. Balancing viscous and electrical stresses reveals that the velocity scales with E 4 / 3. Considering a gas bubble, the external flow is essentially confined to two boundary layers propagating from the poles to the equator, where they collide to form a radial jet. Remarkably, at leading order in the Capillary number the unique scaling allows through application of integral mass and momentum balances to obtain a closed-form expression for the O (E2) bubble deformation. Owing to a concentrated pressure load at the vicinity of the collision region, the deformed profile features an equatorial dimple which is non-smooth on the bubble scale. The dynamical importance of internal circulation in the case of a liquid drop leads to an essentially different deformation mechanism. This is because the external boundary layer velocity attenuates at a short distance from the interface, while the internal boundary-layer matches with a Prandtl-Batchelor (PB) rotational core. The dynamic pressure associated with the internal circulation dominates the interfacial stress profile, leading to an O (E 8 / 3) deformation. The leading-order deformation can be readily determined, up to the PB constant, without solving the circulating boundary-layer problem. To encourage attempts to verify this new scaling, we shall suggest a favourable experimental setup in which inertia is dominant, while finite-deformation, surface-charge advection, and gravity effects are negligible.
Large spin accumulation near a resistive interface due to spin-charge coupling
Chen, Shuhan; Zou, Han; Chui, Siu-Tat; Ji, Yi
2013-12-14
We experimentally and theoretically investigate large spin signals in special nonlocal spin valves, where a vacuum break-junction is formed between the ferromagnetic spin detector and the nonmagnetic channel. The spin signals are clearly nonlocal and can be either non-inverted (meaning high nonlocal resistance for parallel states and low resistance for antiparallel states) or inverted. The magnitudes are significantly larger than those of standard metallic nonlocal devices with similar dimensions. The magnitudes and the signs can be understood by a theory of spin-charge coupling. The coupling between spin accumulation and charge accumulation across a resistive break junction leads to a large interfacial spin accumulation and thereby large spin signals. By analyzing the profiles of electrochemical potentials near the interface, we show that the sign of the spin signal depends on the values of spin-dependent conductivities, diffusion constants, and densities of states. The magnitude of the spin accumulation in the ferromagnetic spin detector can be higher than that in the nonmagnetic channel, enabling a rare amplification effect for spin accumulation.
Saturation of the Magnetorotational Instability at Large Elssaser Number
NASA Astrophysics Data System (ADS)
Julien, Keith; Jamroz, Benjamin; Knobloch, Edgar
2009-11-01
The MRI is believed to play an important role in accretion disk physics in extracting angular momentum from the disk and allowing accretion to take place. The instability is investigated within the shearing box approximation under conditions of fundamental importance to astrophysical accretion disk theory. The shear is taken to be the dominant source of energy, but the instability itself requires the presence of a weaker vertical magnetic field. Dissipative effects are suffiently weak that the Elsasser number is large. Thus dissipative forces do not play a role in the leading order linear instability mechanism. However, they are sufficiently large to permit a nonlinear feedback mechanism whereby the turbulent stresses generated by the MRI act on and modify the local background shear in the angular velocity profile. To date this response has been omitted in shearing box simulations and is captured by a reduced pde model derived from the global MHD fluid equations using multiscale asymptotic perturbation theory. Results from simulations of the model indicate a linear phase of exponential growth followed by a nonlinear adjustment to algebraic growth and decay in the fluctuating quantities. Remarkably, the velocity and magnetic field correlations associated with these growth and decay laws conspire to achieve saturation of angular momentum transport.
Saturation of the magnetorotational instability at large Elsasser number
NASA Astrophysics Data System (ADS)
Jamroz, B.; Julien, K.; Knobloch, E.
2008-09-01
The magnetorotational instability is investigated within the shearing box approximation in the large Elsasser number regime. In this regime, which is of fundamental importance to astrophysical accretion disk theory, shear is the dominant source of energy, but the instability itself requires the presence of a weaker vertical magnetic field. Dissipative effects are weaker still but not negligible. The regime explored retains the condition that (viscous and ohmic) dissipative forces do not play a role in the leading order linear instability mechanism. However, they are sufficiently large to permit a nonlinear feedback mechanism whereby the turbulent stresses generated by the MRI act on and modify the local background shear in the angular velocity profile. To date this response has been omitted in shearing box simulations and is captured by a reduced pde model derived here from the global MHD fluid equations using multiscale asymptotic perturbation theory. Results from numerical simulations of the reduced pde model indicate a linear phase of exponential growth followed by a nonlinear adjustment to algebraic growth and decay in the fluctuating quantities. Remarkably, the velocity and magnetic field correlations associated with these algebraic growth and decay laws conspire to achieve saturation of the angular momentum transport. The inclusion of subdominant ohmic dissipation arrests the algebraic growth of the fluctuations on a longer, dissipative time scale.
Gravity Wave Driven Instabilities at Large Richardson Numbers
NASA Astrophysics Data System (ADS)
Walterscheid, R. L.; Hecht, J. H.; Gelinas, L. J.
2011-12-01
The formalism that addresses rigorously the instability of waves on a basic state modulated by a primary wave is Floquet theory. However, the commonly used criteria for shear and convective instabilities were developed for steady horizontally uniform background flows. The prototypical shear instability is the Kelvin-Helmholtz instability. The flow is stable if the local Richardson number Ri =N2/{\\vert{∂ /∂ z}\\vert}2 > 1/4 everywhere, where N is the Brunt-Väisälä frequency and u is the horizontal wind. The prototypical convective instability is the Rayleigh-Taylor instability. Ignoring wind effects and dissipation, the flow is unstable if N2 < 0 (i.e., Ri <0) somewhere. These instability structures drift with the wind. In Floquet theory the linear system of equations is transformed so that the basic wave is stationary and the vertical coordinate points along the wavenumber vector of the basic wave. A Floquet system supports instabilities when conventional Richardson number criteria indicate that the system is stable. Indeed, finite amplitude waves are unstable no matter how large the Richardson number might be. An essential instability mechanism in Floquet systems is a resonant interaction between a forced primary oscillation and a free oscillation of the time-averaged system. These are parametric instabilities. They can have a significant influence on shaping the spectrum by transferring energy from one scale to another. Hecht et al. [2005] in a study of small scale instability structures during the Maui MALT campaign noted that there were occurrences of ripple (instability) structure when the conventional criteria indicated stable conditions. We have followed up this work with a detailed survey of the occurrence of ripple structure over Maui during periods that were stable and unstable according to conventional criteria. Values of Ri were calculated from meteor radar and lidar data. We have found frequent occurrence of ripple structure when Ri > 1/4 and
Unusually Large Number of Mutations in Asexually Reproducing Clonal Planarian Dugesia japonica.
Nishimura, Osamu; Hosoda, Kazutaka; Kawaguchi, Eri; Yazawa, Shigenobu; Hayashi, Tetsutaro; Inoue, Takeshi; Umesono, Yoshihiko; Agata, Kiyokazu
2015-01-01
We established a laboratory clonal strain of freshwater planarian (Dugesia japonica) that was derived from a single individual and that continued to undergo autotomous asexual reproduction for more than 20 years, and we performed large-scale genome sequencing and transcriptome analysis on it. Despite the fact that a completely clonal strain of the planarian was used, an unusually large number of mutations were detected. To enable quantitative genetic analysis of such a unique organism, we developed a new model called the Reference Gene Model, and used it to conduct large-scale transcriptome analysis. The results revealed large numbers of mutations not only outside but also inside gene-coding regions. Non-synonymous SNPs were detected in 74% of the genes for which valid ORFs were predicted. Interestingly, the high-mutation genes, such as metabolism- and defense-related genes, were correlated with genes that were previously identified as diverse genes among different planarian species. Although a large number of amino acid substitutions were apparently accumulated during asexual reproduction over this long period of time, the planarian maintained normal body-shape, behaviors, and physiological functions. The results of the present study reveal a unique aspect of asexual reproduction. PMID:26588467
Unusually Large Number of Mutations in Asexually Reproducing Clonal Planarian Dugesia japonica
Nishimura, Osamu; Hosoda, Kazutaka; Kawaguchi, Eri; Yazawa, Shigenobu; Hayashi, Tetsutaro; Inoue, Takeshi; Umesono, Yoshihiko; Agata, Kiyokazu
2015-01-01
We established a laboratory clonal strain of freshwater planarian (Dugesia japonica) that was derived from a single individual and that continued to undergo autotomous asexual reproduction for more than 20 years, and we performed large-scale genome sequencing and transcriptome analysis on it. Despite the fact that a completely clonal strain of the planarian was used, an unusually large number of mutations were detected. To enable quantitative genetic analysis of such a unique organism, we developed a new model called the Reference Gene Model, and used it to conduct large-scale transcriptome analysis. The results revealed large numbers of mutations not only outside but also inside gene-coding regions. Non-synonymous SNPs were detected in 74% of the genes for which valid ORFs were predicted. Interestingly, the high-mutation genes, such as metabolism- and defense-related genes, were correlated with genes that were previously identified as diverse genes among different planarian species. Although a large number of amino acid substitutions were apparently accumulated during asexual reproduction over this long period of time, the planarian maintained normal body-shape, behaviors, and physiological functions. The results of the present study reveal a unique aspect of asexual reproduction. PMID:26588467
First Contact with Astronomy for a Large Number of Pupils
NASA Astrophysics Data System (ADS)
Ros, Rosa M.
The Spanish Royal Society of Physics (RSEF) co-operates with several European institutions to promote Physics and Astronomy in schools through the project ""Fisica en Acción"". This project started in 2000 integrated with the project ""Physics on Stage"" created by CERN ESA and ESO. ""Fisica en Accion"" is a Spanish competition bringing together a group of teachers in a common endeavour: * showing ""physics demonstrations"" to general audiences * engaging pedagogical presentations to introduce science into the classroom. The national final event of this competition takes place annually in a science museum during one weekend (entrance is free). The Science Fair is especially well received by visitors who can ask the demonstrators-teachers questions. Younger visitors enjoy experimenting for themselves. After the first year the RSEF introduced special prizes to encourage schools to participate in astronomical categories. The ""Centro de Astrobiologia de Madrid"" gave a cash prize and a visit to their headquarters to the winners. The ""Instituto Astrofísico de Canarias"" offered a prize of a trip to its observatories. In summary the astronomical elements of ""Fisica en Acción"" stimulate the teachers and students' interest in international activities and has been the first contact with Astronomy for a large number of pupils.
A modified large number theory with constant G
NASA Astrophysics Data System (ADS)
Recami, Erasmo
1983-03-01
The inspiring “numerology” uncovered by Dirac, Eddington, Weyl, et al. can be explained and derived when it is slightly modified so to connect the “gravitational world” (cosmos) with the “strong world” (hadron), rather than with the electromagnetic one. The aim of this note is to show the following. In the present approach to the “Large Number Theory,” cosmos and hadrons are considered to be (finite) similar systems, so that the ratio{{bar R} / {{bar R} {bar r}} of the cosmos typical lengthbar R to the hadron typical lengthbar r is constant in time (for instance, if both cosmos and hadrons undergo an expansion/contraction cycle—according to the “cyclical bigbang” hypothesis—thenbar R andbar r can be chosen to be the maximum radii, or the average radii). As a consequence, then gravitational constant G results to be independent of time. The present note is based on work done in collaboration with P. Caldirola, G. D. Maccarrone, and M. Pavšič.
Embury, J.D. |; Han, K.
1999-04-01
The usual method of introducing engineers to the concept of dislocations and their role in plastic flow is to compare an estimate of the theoretical strength of solid (of order {micro}/30 where {micro} is the shear modulus) and the observed strength of either single crystals ({mu}/10{sup 4}) or practical engineering material such as structural steels where the yield stress in shear is of order {mu}/10{sup 3}. However, if one considers the problem in reverse, one can consider the accumulation of dislocations as an important mechanism by which one can produce engineering materials in which the strength level approaches the theoretical strength. If one assumes that the flow stress can be expressed in terms of te mean free path between stored dislocations or as the square root of the global dislocation density, then one can see the influence of dislocation density in a diagrammatic form. It is clear that the strengthening by dislocation accumulation due to large imposed plastic strains represents an important approach both to the development of new, potentially valuable, engineering materials and an important area of basic understanding in terms of the mechanical response of materials close to their theoretical strength. Thus, this article will survey some of the factors which influence dislocation accumulation at large strains and the consequences of such accumulation processes.
A large-scale genetic screen for mutants with altered salicylic acid accumulation in Arabidopsis
Ding, Yezhang; Shaholli, Danjela; Mou, Zhonglin
2014-01-01
Salicylic acid (SA) is a key defense signal molecule against biotrophic and hemibiotrophic pathogens in plants, but how SA is synthesized in plant cells still remains elusive. Identification of new components involved in pathogen-induced SA accumulation would help address this question. To this end, we performed a large-scale genetic screen for mutants with altered SA accumulation during pathogen infection in Arabidopsis using a bacterial biosensor Acinetobacter sp. ADPWH_lux-based SA quantification method. A total of 35,000 M2 plants in the npr1-3 mutant background have been individually analyzed for the bacterial pathogen Pseudomonas syringae pv. maculicola (Psm) ES4326-induced SA accumulation. Among the mutants isolated, 19 had SA levels lower than npr1 (sln) and two exhibited increased SA accumulation in npr1 (isn). Complementation tests revealed that seven of the sln mutants are new alleles of eds5/sid1, two are sid2/eds16 alleles, one is allelic to pad4, and the remaining seven sln and two isn mutants are new non-allelic SA accumulation mutants. Interestingly, a large group of mutants (in the npr1-3 background), in which Psm ES4326-induced SA levels were similar to those in the wild-type Columbia plants, were identified, suggesting that the signaling network fine-tuning pathogen-induced SA accumulation is complex. We further characterized the sln1 single mutant and found that Psm ES4326-induced defense responses were compromised in this mutant. These defense response defects could be rescued by exogenous SA, suggesting that SLN1 functions upstream of SA. The sln1 mutation was mapped to a region on the north arm of chromosome I, which contains no known genes regulating pathogen-induced SA accumulation, indicating that SLN1 likely encodes a new regulator of SA biosynthesis. Thus, the new sln and isn mutants identified in this genetic screen are valuable for dissecting the molecular mechanisms underlying pathogen-induced SA accumulation in plants. PMID:25610446
Steady bimodal convection in a cylinder at large Prandtl numbers
NASA Technical Reports Server (NTRS)
Buell, Jeffrey C.; Catton, Ivan
1987-01-01
Steady bimodal convection of an infinite Prandtl-number Boussinesq fluid in a cylinder is considered. An asymptotic analysis similar to the one used by Buell and Catton (1986) for axisymmetric convection yields a solvability condition that determines the radial wavenumber. The analysis is valid for convection far away from the origin, the lateral boundary, and any pattern dislocations. The azimuthal wave number is treated as a parameter, although in real systems it is dependent on the initial and boundary conditions. Results are presented for Rayleigh numbers between 14,000 and 60,000, and for azimuthal wave numbers between 5 and 7. It is shown that for increasing Rayleigh numbers, the selected radial wave number and the heat transfer tend to become independent of the azimuthal wave number. No quantitative experimental data are available, but one qualitative comparison is good.
Generation of large prime numbers from a sequence of previous prime numbers
NASA Astrophysics Data System (ADS)
Samir, Brahim Belhaouari; Rezk, Youssef A. Y.
2012-09-01
A prime number is co-prime with all the primes as well. This paper utilizes this fact by generating larger prime numbers based on a set of smaller prime numbers. The prime numbers are ordered and each two consecutive primes are coupled to generate their co-prime number formula extending this process larger prime sequence is established. Will the process help us produce larger prime numbers faster and more efficiently? This paper investigates the described process.
27% Probable: Estimating Whether or Not Large Numbers Are Prime.
ERIC Educational Resources Information Center
Bosse, Michael J.
2001-01-01
This brief investigation exemplifies such considerations by relating concepts from number theory, set theory, probability, logic, and calculus. Satisfying the call for students to acquire skills in estimation, the following technique allows one to "immediately estimate" whether or not a number is prime. (MM)
Exploring the Potential of Large Scale Distributed Modeling of Snow Accumulation and Melt on GPUs
NASA Astrophysics Data System (ADS)
Bisht, G.; Kumar, M.
2010-12-01
Water from snow melt is a critical resource in watersheds of the western US, Canada, and other similar regions of the world. The distribution of snow and melt-water controls the temporal and spatial distributions of soil moisture, evapo-transpiration (ET), recharge, stream-aquifer interaction and other hydrologic processes within the watershed. It also influences the quantity and timing of water availability in downstream areas. In spite of the serious impacts on the water resources at multiple scales, the knowledge base for prediction of snow accumulation and melt in mountainous watersheds is notably weak. Physics-based, distributed snow models such as UEB, SNTHERM, SHAW and ISNOBAL, have positioned themselves as an appropriate tool for understanding of snow-process interactions and prediction of melt, and have been applied in numerous watersheds to varying degrees of success. In spite of the significant advances in hardware speed and programming efficiency, the application of the above-mentioned snow models has mostly been limited to small watersheds. Application of these models at finer spatio-temporal resolution, in large domains, and for longer time periods, to address problems such as quantifying the response of snow-dominated watersheds to climate change scenarios, is restrictive due to the large computational cost involved. Additionally, the computational requirement of current generation snow models is expected to rise as improved snow-depth characterization and a tighter coupling with hydrologic processes are incorporated. This poses considerable challenge to their application in feasible time. We suggest alleviating this problem by taking advantage of high performance computing (HPC) systems based on Graphics Processing Unit (GPU) processors. High performance GPUs work like SIMD processors, but can take advantage of larger number of cores thus providing higher throughput. As of June 2010, the second fastest supercomputer in the world uses NVidia Tesla
A MODEL OF NONBELIEF IN THE LAW OF LARGE NUMBERS
Benjamin, Daniel J.; Rabin, Matthew; Raymond, Collin
2015-01-01
People believe that, even in very large samples, proportions of binary signals might depart significantly from the population mean. We model this “non-belief in the Law of Large Numbers” by assuming that a person believes that proportions in any given sample might be determined by a rate different than the true rate. In prediction, a non-believer expects the distribution of signals will have fat tails. In inference, a non-believer remains uncertain and influenced by priors even after observing an arbitrarily large sample. We explore implications for beliefs and behavior in a variety of economic settings. PMID:27087795
Physical mechanisms that lead to large-scale gas accumulation in a volcanic conduit
NASA Astrophysics Data System (ADS)
Collombet, Marielle; Burgisser, Alain
2016-04-01
The eruption of viscous magma at the Earth's surface often gives rise to abrupt regime changes. The transition from the gentle effusion of a lava dome to brief but powerful explosions is a common regime change. This transition is often preceded by the sealing of the shallow part of the volcanic conduit and the accumulation of volatile-rich magma underneath, a situation that collects the energy to be brutally released during the subsequent explosion. While conduit sealing is well-documented, volatile accumulation has proven harder to characterize. We use a 2D conduit flow model including gas loss within the magma and into the wallrock to find steady-state magma flow configurations in the effusive regime. Model outputs yield a strongly heterogeneous distribution of the gas volume fraction underneath a dense, impermeable magma cap. Gas accumulates in inclined structures hundredths of meters long and several meters thick. These structures probably constitute the gas pockets that accumulate explosive energy and that were intuited by previous studies. We tested the numerical robustness of our results by simulating the fragmented state of the magma contained within the pockets, by testing various fragmentation criteria, and by varying computational gird size. These gas pockets are robust features that occur regardless of wallrock permeability (from very permeable at 10-12 m2 to quasi impermeable at 10-16 m2) but that are sensitive to the volume to surface ratio of the volcanic conduit. One implication is that the formation of these large degassing structures probably plays an essential role in the triggering of violent explosions. Such large scale outgassing feature may also bring a partial answer to the long standing issue of the observed gas transfer across entire magmatic systems despite high magma viscosity and no obvious physical mechanism of transfer.
Large atom number Bose-Einstein condensate machines
Streed, Erik W.; Chikkatur, Ananth P.; Gustavson, Todd L.; Boyd, Micah; Torii, Yoshio; Schneble, Dominik; Campbell, Gretchen K.; Pritchard, David E.; Ketterle, Wolfgang
2006-02-15
We describe experimental setups for producing large Bose-Einstein condensates of {sup 23}Na and {sup 87}Rb. In both, a high-flux thermal atomic beam is decelerated by a Zeeman slower and is then captured and cooled in a magneto-optical trap. The atoms are then transferred into a cloverleaf-style Ioffe-Pritchard magnetic trap and cooled to quantum degeneracy with radio-frequency-induced forced evaporation. Typical condensates contain 20x10{sup 6} atoms. We discuss the similarities and differences between the techniques used for producing large {sup 87}Rb and {sup 23}Na condensates in the context of nearly identical setups.
Confinement at large-N. [N = number of colors
Klinkhamer, F.R.
1985-06-01
Recent numerical results indicate that QCD in the limit of an infinite number (N) of colors also has confinement and moreover that it looks rather similar to normal QCD with N = 3 colors. This imposes severe restrictions on what the mechanism of confinement can be.
Volcanism on Venus: Large shields and major accumulations of small domes
NASA Technical Reports Server (NTRS)
Schaber, Gerald G.; Kozak, Richard C.
1989-01-01
The outer layers of the Venusian lithosphere appear to dissipate heat from the interior through mantle-driven thermal anomalies (hot spots, swells). As a result, Venus exhibits diverse forms of thin-skin tectonism and magmatic transfer to and extrusion from countless numbers of volcanic centers (e.g., shields, paterae, domes) and volcano-tectonic complexes (e.g., coronae, arachnoids). What is known about the distribution and morphologies of major Venusian shields is summarized, and the evidence for possible structural control of major accumulations as long as 5000 km of small volcanic domes is described.
Volcanism on Venus: Large shields and major accumulations of small domes
NASA Astrophysics Data System (ADS)
Schaber, Gerald G.; Kozak, Richard C.
The outer layers of the Venusian lithosphere appear to dissipate heat from the interior through mantle-driven thermal anomalies (hot spots, swells). As a result, Venus exhibits diverse forms of thin-skin tectonism and magmatic transfer to and extrusion from countless numbers of volcanic centers (e.g., shields, paterae, domes) and volcano-tectonic complexes (e.g., coronae, arachnoids). What is known about the distribution and morphologies of major Venusian shields is summarized, and the evidence for possible structural control of major accumulations as long as 5000 km of small volcanic domes is described.
Planing-surface Tests at Large Froude Numbers - Airfoil Comparison
NASA Technical Reports Server (NTRS)
Sambraus, A
1938-01-01
The take-off capacity of a flying boat depends upon the design of the hull bottom ahead as well as aft of the step. Systematic tests - largely made by industry itself - had proved the benefit accruing from a well designed hull bottom long before theoretical insight into the flow phenomena involved had been obtained. The theoretical framing of the problem was beset with serious difficulties and, though restricted to the processes within range of the planing bottom ahead of the step, the solutions do not yet afford a comprehensive survey.
Calcite-accumulating large sulfur bacteria of the genus Achromatium in Sippewissett Salt Marsh.
Salman, Verena; Yang, Tingting; Berben, Tom; Klein, Frieder; Angert, Esther; Teske, Andreas
2015-11-01
Large sulfur bacteria of the genus Achromatium are exceptional among Bacteria and Archaea as they can accumulate high amounts of internal calcite. Although known for more than 100 years, they remain uncultured, and only freshwater populations have been studied so far. Here we investigate a marine population of calcite-accumulating bacteria that is primarily found at the sediment surface of tide pools in a salt marsh, where high sulfide concentrations meet oversaturated oxygen concentrations during the day. Dynamic sulfur cycling by phototrophic sulfide-oxidizing and heterotrophic sulfate-reducing bacteria co-occurring in these sediments creates a highly sulfidic environment that we propose induces behavioral differences in the Achromatium population compared with reported migration patterns in a low-sulfide environment. Fluctuating intracellular calcium/sulfur ratios at different depths and times of day indicate a biochemical reaction of the salt marsh Achromatium to diurnal changes in sedimentary redox conditions. We correlate this calcite dynamic with new evidence regarding its formation/mobilization and suggest general implications as well as a possible biological function of calcite accumulation in large bacteria in the sediment environment that is governed by gradients. Finally, we propose a new taxonomic classification of the salt marsh Achromatium based on their adaptation to a significantly different habitat than their freshwater relatives, as indicated by their differential behavior as well as phylogenetic distance on 16S ribosomal RNA gene level. In future studies, whole-genome characterization and additional ecophysiological factors could further support the distinctive position of salt marsh Achromatium. PMID:25909974
Bose-Einstein Condensates with Large Number of Vortices
Ho, Tin-Lun
2001-08-06
We show that as the number of vortices in a three dimensional Bose-Einstein condensate increases, the system reaches a ''quantum Hall'' regime where the density profile is a Gaussian in the xy plane and an inverted parabolic profile along z . The angular momentum of the system increases as the vortex lattice shrinks. However, Coriolis force prevents the unit cell of the vortex lattice from shrinking beyond a minimum size. Although the recent MIT experiment is not exactly in the quantum Hall regime, it is close enough for the present results to be used as a guide. The quantum Hall regime can be easily reached by moderate changes of the current experimental parameters.
The Number of Accumulated Photons and the Quality of Stimulated Emission Depletion Lifetime Images
Syed, Aleem; Lesoine, Michael D; Bhattacharjee, Ujjal; Petrich, Jacob W; Smith, Emily A
2014-03-03
Time binning is used to increase the number of photon counts in the peak channel of stimulated emission depletion (STED) fluorescence lifetime decay curves to determine how it affects the resulting lifetime image. The fluorescence lifetime of the fluorophore, Alexa Fluor 594 phalloidin, bound to F-actin is probed in cultured S2 cells at a spatial resolution of ~40 nm. This corresponds to a tenfold smaller probe volume compared to confocal imaging, and a reduced number of photons contributing to the signal. Pixel-by-pixel fluorescence lifetime measurements and error analysis show that an average of 40 ± 30 photon counts in the peak channel with a signal-to-noise ratio of 20 is enough to calculate a reliable fluorescence lifetime from a single exponential fluorescence decay. No heterogeneity in the actin cytoskeleton in different regions of the cultured cells was measured in the 40- to 400-nm spatial regime.
NASA Astrophysics Data System (ADS)
Macka, Zdenek; Krejci, Lukas
2010-05-01
Large woody debris (LWD) in the form of logs, branches and their fragments play an important geomorphic and ecological role in forested watersheds. Especially when organized in accumulations and jams, LWD have been found to change hydraulic, morphological, sedimentary and biological characteristics of fluvial ecosystems. Our study focuses on LWD jams distribution and properties within the 44 km long forested reach of the Dyje River in south-eastern Czech Republic. The study reach is located between two large water reservoirs and the flow is regulated showing significant daily fluctuation of discharges due to water releases for power generation. River flows in the deeply incised meandering valley with the narrow and patchy floodplain. In 2002, and especially 2006 large volumes of LWD have been transported by river and the water reservoir downstream was congested with wood. Peak discharge of 2006 flood equalled 306 m3.s-1 which was estimated as 500 year flood. The flood caused significant mobility and redistribution of woody debris as in aquatic, so in riparian segment of the river corridor. The high rate of LWD transport is favoured by large bankfull channel width which exceeds the average tree height. LWD jams were defined as aggregations of three or more wood pieces with diameter ≥ 0.1 m and length ≥ 1 m. We surveyed LWD jams in 62 river reaches, which have been located at meander apexes, inflections and intermediate positions; the length of the reaches was 200 m. The overall number of registered LWD jams was 200. Majority of jams consist of solely allochthonous (transported) wood pieces (65 %), some jams are combination of large key trees and trapped transported pieces (29%), and only small proportion are jams formed by locally uprooted trees (12,6%). Number of wood pieces varies greatly from 3 to 98, the most common being the interval 5 - 10 pieces per jam. Spatial distribution of jams is longitudinally and transversally irregular within the river corridor
Maricq, M Matti; Szente, Joseph J; Adams, Jack; Tennison, Paul; Rumpsa, Todd
2013-10-15
Gasoline direct injection (GDI) is a new engine technology intended to improve fuel economy and greenhouse gas emissions as required by recently enacted legislative and environmental regulations. The development of this technology must also ensure that these vehicles meet new LEV III and Tier 3 emissions standards as they phase in between 2017 and 2021. The aim of the present paper is to examine, at least for a small set, how the PM emissions from GDI vehicles change over their lifetime. The paper reports particle mass and number emissions of two GDI vehicles as a function of mileage up to 150K miles. These vehicles exhibit PM emissions that are near or below the upcoming 3 mg/mi FTP and 10 mg/mi US06 mass standards with little, if any, deterioration over 150K miles. Particle number emissions roughly follow the previously observed 2 × 10(12) particles/mg correlation between solid particle number and PM mass. They remained between the interim and final EU stage 6 solid particle count standard for gasoline vehicles throughout the mileage accumulation study. These examples demonstrate feasibility to meet near-term 3 mg/mi and interim EU solid particle number standards, but continued development is needed to ensure that this continues as further fuel economy improvements are made. PMID:24040936
NASA Astrophysics Data System (ADS)
Xu, S.; Fukuyama, E.; Yamashita, F.; Mizoguchi, K.; Takizawa, S.; Kawakata, H.
2014-12-01
We report results with Indian Gabbro (Vs=3.62km/s) that are obtained from a series of large-scale biaxial friction experiments conducted at NIED. We focus on strain gage array data of stick-slip events loaded with 0.01mm/s and under 6.7MPa normal stress, and find the following: (1) During early stage when the contact surface is relatively intact, ruptures mainly behave as slow-slip events, with a transition from extremely slow slip (~ 10 m/s) to normal slow slip (~ 100 m/s). (2) With the accumulation of total fault displacement, grooves indicative of locally high normal-stress patches (i.e. asperities) are generated along the sliding surface, which are primarily elongated along the loading direction and are associated with gouge formation. On the other hand, the rest part of the surface continues being polished, indicated by a contrast in light reflectivity with respect to the initial level. At this stage, rupture speeds start to increase but are still well below the shear wave speed (~ 1/4Vs). (3) After long enough total fault displacement (> 500mm), grooves and gouges of a sufficient amount are generated. The following ruptures then show a classic behavior as documented by Ohnaka (2000), which composes of a quasi-static phase, an accelerating phase, and an unstable propagation phase. Although the terminal propagation speed usually reaches a level comparable to the shear wave speed, there is a significant variability for the earlier phases among different events, suggesting that those earlier phases are more sensitive to the evolving local fault structure and/or stress heterogeneity. Further investigation reveals that fault properties (e.g. grooves and gouges) as a function of the accumulated displacement can influence both the macroscopic and the local strain drop, which are most-likely responsible for the evolution of rupture behavior under the same macroscopic loading conditions. We aim to quantify this relation in a continued study.
NASA Astrophysics Data System (ADS)
Tahara, Takayuki; Ando, Yuichiro; Kameno, Makoto; Koike, Hayato; Tanaka, Kazuhito; Miwa, Shinji; Suzuki, Yoshishige; Sasaki, Tomoyuki; Oikawa, Tohru; Shiraishi, Masashi
2016-06-01
A large spin accumulation voltage of more than 1.5 mV at 1 mA, i.e., a magnetoresistance of 1.5 Ω, was measured by means of the local three-terminal magnetoresistance in nondegenerate Si-based lateral spin valves (LSVs) at room temperature. This is the largest spin accumulation voltage measured in semiconductor-based LSVs. The modified spin drift-diffusion model, which successfully accounts for the spin drift effect, explains the large spin accumulation voltage and significant bias-current-polarity dependence. The model also shows that the spin drift effect enhances the spin-dependent magnetoresistance in the electric two-terminal scheme. This finding provides a useful guiding principle for spin metal-oxide-semiconductor field-effect transistor operations.
Gardiol, Alejandra; St Johnston, Daniel
2014-01-01
The post-synaptic translation of localised mRNAs has been postulated to underlie several forms of plasticity at vertebrate synapses, but the mechanisms that target mRNAs to these postsynaptic sites are not well understood. Here we show that the evolutionary conserved dsRNA binding protein, Staufen, localises to the postsynaptic side of the Drosophila neuromuscular junction (NMJ), where it is required for the localisation of coracle mRNA and protein. Staufen plays a well-characterised role in the localisation of oskar mRNA to the oocyte posterior, where Staufen dsRNA-binding domain 5 is specifically required for its translation. Removal of Staufen dsRNA-binding domain 5, disrupts the postsynaptic accumulation of Coracle protein without affecting the localisation of cora mRNA, suggesting that Staufen similarly regulates Coracle translation. Tropomyosin II, which functions with Staufen in oskar mRNA localisation, is also required for coracle mRNA localisation, suggesting that similar mechanisms target mRNAs to the NMJ and the oocyte posterior. Coracle, the orthologue of vertebrate band 4.1, functions in the anchoring of the glutamate receptor IIA subunit (GluRIIA) at the synapse. Consistent with this, staufen mutant larvae show reduced accumulation of GluRIIA at synapses. The NMJs of staufen mutant larvae have also a reduced number of synaptic boutons. Altogether, this suggests that this novel Staufen-dependent mRNA localisation and local translation pathway may play a role in the developmentally regulated growth of the NMJ. PMID:24951879
Gardiol, Alejandra; St Johnston, Daniel
2014-08-15
The post-synaptic translation of localised mRNAs has been postulated to underlie several forms of plasticity at vertebrate synapses, but the mechanisms that target mRNAs to these postsynaptic sites are not well understood. Here we show that the evolutionary conserved dsRNA binding protein, Staufen, localises to the postsynaptic side of the Drosophila neuromuscular junction (NMJ), where it is required for the localisation of coracle mRNA and protein. Staufen plays a well-characterised role in the localisation of oskar mRNA to the oocyte posterior, where Staufen dsRNA-binding domain 5 is specifically required for its translation. Removal of Staufen dsRNA-binding domain 5, disrupts the postsynaptic accumulation of Coracle protein without affecting the localisation of cora mRNA, suggesting that Staufen similarly regulates Coracle translation. Tropomyosin II, which functions with Staufen in oskar mRNA localisation, is also required for coracle mRNA localisation, suggesting that similar mechanisms target mRNAs to the NMJ and the oocyte posterior. Coracle, the orthologue of vertebrate band 4.1, functions in the anchoring of the glutamate receptor IIA subunit (GluRIIA) at the synapse. Consistent with this, staufen mutant larvae show reduced accumulation of GluRIIA at synapses. The NMJs of staufen mutant larvae have also a reduced number of synaptic boutons. Altogether, this suggests that this novel Staufen-dependent mRNA localisation and local translation pathway may play a role in the developmentally regulated growth of the NMJ. PMID:24951879
Polyfunctional T cells accumulate in large human cytomegalovirus-specific T cell responses.
Lachmann, Raskit; Bajwa, Martha; Vita, Serena; Smith, Helen; Cheek, Elizabeth; Akbar, Arne; Kern, Florian
2012-01-01
Large cytomegalovirus (CMV)-specific CD8 T-cell responses are observed in both young and, somewhat more often, old people. Frequent CMV reactivation is thought to exhaust these cells and render them dysfunctional so that larger numbers of them are needed to control CMV. Expansions of CMV-specific CD4 T cells are also seen but are less well studied. In this study, we examined the T-cell response to the dominant CMV pp65 and IE-1 antigens in healthy CMV-infected people across a wide age range (20 to 84 years) by using multicolor flow cytometry. CMV-specific T cells were characterized by the activation markers CD40 ligand (CD40L), interleukin-2 (IL-2), tumor necrosis factor alpha (TNF-α), and gamma interferon (IFN-γ) and the memory markers CD27 and CD45RA. The proportions of effector memory T cells increased in large responses, as did the proportions of polyfunctional CD8 (IFN-γ(+) IL-2(+/-) TNF-α(+)) and CD4 (CD40L(+/-) IFN-γ(+) IL-2(+) TNF-α(+)) T-cell subsets, while the proportion of naïve T cells decreased. The bigger the CD4 or CD8 T-cell response to pp65, the larger was the proportion of T cells with an advanced memory phenotype in the entire (including non-CMV-specific) T-cell compartment. In addition, the number of activation markers per cell correlated with the degree of T-cell receptor downregulation, suggesting increased antigen sensitivity in polyfunctional cells. In summary, our findings show that polyfunctional CMV-specific T cells were not superseded by dysfunctional cells, even in very large responses. At the same time, however, the memory subset composition of the entire T-cell compartment correlated with the size of the T-cell response to CMV pp65, confirming a strong effect of CMV infection on the immune systems of some, but not all, infected people. PMID:22072753
Gomez, T; Sagaut, P; Schilling, O; Zhou, Y
2006-07-05
A spectral subggrid-scale eddy viscosity and magnetic resisitivity model based on the eddy-damped quasi-normal Markovian (EDQNM) spectral kinetic and magnetic energy transfer presented in [12] is used in large-eddy simulation (LES) of large kinetic and magnetic Reynold number magneto-hydrodynamic (MHD) turbulence. The proposed model is assessed via a posteri tests on three-dimensional, incompressible, isotropic, non-helical, freely-decaying MHD turbulence at asymptotically large Reynolds numbers. Using LES with an initial condition characterized by an Alfv{acute e}n ratio of kinetic to magnetic energy {tau}{sub A} equal to unity, it is shown that at the kinetic energy spectrum E{sub K}(k) and magnetic energy spectrum E{sub M}(k) exhibit Kolmogorov -5/3 inertial subrange scalings in the LES, consistent with the EDQNM model.
How and why does tomato accumulate a large amount of GABA in the fruit?
Takayama, Mariko; Ezura, Hiroshi
2015-01-01
Gamma-aminobutyric acid (GABA) has received much attention as a health-promoting functional compound, and several GABA-enriched foods have been commercialized. In higher plants, GABA is primarily metabolized via a short pathway called the GABA shunt. The GABA shunt bypasses two steps (the oxidation of α-ketoglutarate to succinate) of the tricarboxylic acid (TCA) cycle via reactions catalyzed by three enzymes: glutamate decarboxylase, GABA transaminase, and succinic semialdehyde dehydrogenase. The GABA shunt plays a major role in primary carbon and nitrogen metabolism and is an integral part of the TCA cycle under stress and non-stress conditions. Tomato is one of the major crops that accumulate a relatively high level of GABA in its fruits. The GABA levels in tomato fruits dramatically change during fruit development; the GABA levels increase from flowering to the mature green stage and then rapidly decrease during the ripening stage. Although GABA constitutes up to 50% of the free amino acids at the mature green stage, the molecular mechanism of GABA accumulation and the physiological function of GABA during tomato fruit development remain unclear. In this review, we summarize recent studies of GABA accumulation in tomato fruits and discuss the potential biological roles of GABA in tomato fruit development. PMID:26322056
ERIC Educational Resources Information Center
Slaughter, Virginia; Kamppi, Dorian; Paynter, Jessica
2006-01-01
Two experiments were conducted to test the hypothesis that toddlers have access to an analog-magnitude number representation that supports numerical reasoning about relatively large numbers. Three-year-olds were presented with subtraction problems in which initial set size and proportions subtracted were systematically varied. Two sets of cookies…
Rhesus Monkeys ("Macaca Mulatta") Spontaneously Compute Addition Operations Over Large Numbers
ERIC Educational Resources Information Center
Flombaum, Jonathan I.; Junge, Justin A.; Hauser, Marc D.
2005-01-01
Mathematics is a uniquely human capacity. Studies of animals and human infants reveal, however, that this capacity builds on language-independent mechanisms for quantifying small numbers ([less than] 4) precisely and large numbers approximately. It is unclear whether animals and human infants can spontaneously tap mechanisms for quantifying large…
NASA Astrophysics Data System (ADS)
Kunz, Manuel J.; Anselmetti, Flavio S.; Wüest, Alfred; Wehrli, Bernhard; Vollenweider, Adrian; Thüring, Silvan; Senn, David B.
2011-09-01
Large dams affect the aquatic continuum from land to ocean by accumulating particles and nutrients in their reservoirs. We examined sediment cores to quantify sediment, organic carbon (OC), nitrogen (N), and phosphorous (P) accumulation, and to examine historic changes and spatial variability in the sedimentation pattern in Lake Kariba, the largest hydropower reservoir in the Zambezi River Basin (ZRB). Sediment characteristics (concentrations of OC, N, P; δ13C and δ15N; wet bulk density) showed large variability both with sediment depth and between cores. While organic matter (OM) in river deltas was primarily allochthonous in origin, OM characteristics (δ13C, C:N) in lacustrine sediments suggest that autochthonous sources account for >45% of the OM that accumulates over large areas of the lake. At the same time, the relative contribution of allochthonous material within individual layers of lacustrine cores varied considerably with depth due to discrete flood deposits. The overall sediment accumulation rate in Lake Kariba is on the order of 4 × 106 t yr-1, and the estimated OC accumulation of 120 × 103 t C yr-1 accounts for ˜1‰ of globally buried OC in reservoirs. In addition, mass balance calculations revealed that approximately 70% and 90% of incoming total N and P, respectively, are eliminated from the water column by sedimentation (N, P) and denitrification (N). Since Lake Kariba attenuates flow from ˜50% of the ZRB, these OC, N, and P removals represent a drastic reduction in nutrient loadings to downstream riparian ecosystems and to the coastal Indian Ocean.
Very Large Data Volumes Analysis of Collaborative Systems with Finite Number of States
ERIC Educational Resources Information Center
Ivan, Ion; Ciurea, Cristian; Pavel, Sorin
2010-01-01
The collaborative system with finite number of states is defined. A very large database is structured. Operations on large databases are identified. Repetitive procedures for collaborative systems operations are derived. The efficiency of such procedures is analyzed. (Contains 6 tables, 5 footnotes and 3 figures.)
Lessons learned in preparing to receive large numbers of contaminated individuals.
Miller, Ken; Groff, Lee; Erdman, Mike; King, Steve
2005-08-01
Traditionally, medical radiation emergency plans have provided for the receipt and care of a limited number of individuals, usually no more than two or three at any given time. Large numbers of contaminated, uninjured individuals cannot be effectively handled in the emergency departments (EDs) of hospitals as they present a risk of forcing the ED to close because of contamination and they divert ED personnel away from patients needing medical attention. Alternative locations and plans for handling large numbers of contaminated but otherwise uninjured patients must be considered. Such plans developed at the Penn State Hershey Medical Center (HMC) during the 1979 accident at the Three Mile Island Nuclear Power Plant (TMI) were resurrected post 9/11 and used there in developing and upgrading plans and capabilities for handling large numbers of contaminated, uninjured individuals. PMID:16010120
Solar concentration properties of flat fresnel lenses with large F-numbers
NASA Technical Reports Server (NTRS)
Cosby, R. M.
1978-01-01
The solar concentration performances of flat, line-focusing sun-tracking Fresnel lenses with selected f-numbers between 0.9 and 2.0 were analyzed. Lens transmittance was found to have a weak dependence on f-number, with a 2% increase occuring as the f-number is increased from 0.9 to 2.0. The geometric concentration ratio for perfectly tracking lenses peaked for an f-number near 1.35. Intensity profiles were more uniform over the image extent for large f-number lenses when compared to the f/0.9 lens results. Substantial decreases in geometri concentration ratios were observed for transverse tracking errors equal to or below 1 degree for all f-number lenses. With respect to tracking errors, the solar performance is optimum for f-numbers between 1.25 and 1.5.
Large Eddy Simulations of Kelvin Helmholtz instabilities at high Reynolds number stratified flows
NASA Astrophysics Data System (ADS)
Brown, Dana; Goodman, Lou; Raessi, Mehdi
2015-11-01
Simulations of Kelvin Helmholtz Instabilities (KHI) at high Reynolds numbers are performed using the Large Eddy Simulation technique. Reynolds numbers up to 100,000 are achieved using our model. The resulting data set is used to examine the effect of Reynolds number on various statistics, including dissipation flux coefficient, turbulent kinetic energy budget, and Thorpe length scale. It is shown that KHI are qualitatively different at high Re, up to and including the onset of vortex pairing and billow collapse and quantitatively different afterward. The effect of Richardson number is also examined. The results are discussed as they apply to ocean experiments.
On the architecture for the X part of a very large FX correlator using two-accumulator CMACs
NASA Astrophysics Data System (ADS)
Lapshev, Stepan; Rezaul Hasan, S. M.
2016-02-01
This paper presents an improved input-buffer architecture for the X part of a very large FX correlator that optimizes memory use to both increase performance and reduce the overall power consumption. The architecture uses an array of two-accumulator CMACs that are reused for different pairs of correlated signals. Using two accumulators in every CMAC allows the processing array to alternately correlate two sets of signal pairs selected in such a way so that they share some or all of the processed data samples. This leads to increased processing bandwidth and a significant reduction of the memory read rate due to not having to update some or all of the processing buffers in every second processing cycle. The overall memory access rate is at most 75 % of that of the single-accumulator CMAC array. This architecture is intended for correlators of very large multi-element radio telescopes such as the Square Kilometre Array (SKA), and is suitable for an ASIC implementation.
On large-scale dynamo action at high magnetic Reynolds number
Cattaneo, F.; Tobias, S. M.
2014-07-01
We consider the generation of magnetic activity—dynamo waves—in the astrophysical limit of very large magnetic Reynolds number. We consider kinematic dynamo action for a system consisting of helical flow and large-scale shear. We demonstrate that large-scale dynamo waves persist at high Rm if the helical flow is characterized by a narrow band of spatial scales and the shear is large enough. However, for a wide band of scales the dynamo becomes small scale with a further increase of Rm, with dynamo waves re-emerging only if the shear is then increased. We show that at high Rm, the key effect of the shear is to suppress small-scale dynamo action, allowing large-scale dynamo action to be observed. We conjecture that this supports a general 'suppression principle'—large-scale dynamo action can only be observed if there is a mechanism that suppresses the small-scale fluctuations.
Central Limit Theorems and Uniform Laws of Large Numbers for Arrays of Random Fields
Jenish, Nazgul; Prucha, Ingmar R.
2009-01-01
Over the last decades, spatial-interaction models have been increasingly used in economics. However, the development of a sufficiently general asymptotic theory for nonlinear spatial models has been hampered by a lack of relevant central limit theorems (CLTs), uniform laws of large numbers (ULLNs) and pointwise laws of large numbers (LLNs). These limit theorems form the essential building blocks towards developing the asymptotic theory of M-estimators, including maximum likelihood and generalized method of moments estimators. The paper establishes a CLT, ULLN, and LLN for spatial processes or random fields that should be applicable to a broad range of data processes. PMID:20161289
Multiple paternity: determining the minimum number of sires of a large brood.
Eriksson, A; Mehlig, B; Panova, M; Andre, C; Johannesson, K
2010-03-01
We describe an efficient algorithm for determining exactly the minimum number of sires consistent with the multi-locus genotypes of a mother and her progeny. We consider cases where a simple exhaustive search through all possible sets of sires is impossible in practice because it would take too long to complete. Our algorithm for solving this combinatorial optimization problem avoids visiting large parts of search space that would not result in a solution with fewer sires. This improvement is of particular importance when the number of allelic types in the progeny array is large and when the minimum number of sires is expected to be large. Precisely in such cases, it is important to know the minimum number of sires: this number gives an exact bound on the most likely number of sires estimated by a random search algorithm in a parameter region where it may be difficult to determine whether it has converged. We apply our algorithm to data from the marine snail, Littorina saxatilis. PMID:21565023
NASA Astrophysics Data System (ADS)
Fox, Rodney O.; Vie, Aymeric; Laurent, Frederique; Chalons, Christophe; Massot, Marc
2012-11-01
Numerous applications involve a disperse phase carried by a gaseous flow. To simulate such flows, one can resort to a number density function (NDF) governed a kinetic equation. Traditionally, Lagrangian Monte-Carlo methods are used to solve for the NDF, but are expensive as the number of numerical particles needed must be large to control statistical errors. Moreover, such methods are not well adapted to high-performance computing because of the intrinsic inhomogeneity of the NDF. To overcome these issues, Eulerian methods can be used to solve for the moments of the NDF resulting in an unclosed Eulerian system of hyperbolic conservation laws. To obtain closure, in this work a multivariate bi-Gaussian quadrature is used, which can account for particle trajectory crossing (PTC) over a large range of Stokes numbers. This closure uses up to four quadrature points in 2-D velocity phase space to capture large-scale PTC, and an anisotropic Gaussian distribution around each quadrature point to model small-scale PTC. Simulations of 2-D particle-laden isotropic turbulence at different Stokes numbers are employed to validate the Eulerian models against results from the Lagrangian approach. Good agreement is found for the number density fields over the entire range of Stokes numbers tested. Research carried out at the Center for Turbulence Research 2012 Summer Program.
NASA Astrophysics Data System (ADS)
Monod, R.; Brillant, G.; Toutant, A.; Bataille, F.
2012-11-01
Thermal striping is one of the possible initiator of pipe rupture. In this framework, thermal fluctuations in a heated periodic channel have been calculated using Large Eddy Simulation (LES). The fluid Prandtl number is set to 0.01 and the friction Reynolds number to 395. The Werner and Wengle Wall Function is used with the Navier-Stokes equations to reduce the computational cost. Satisfactory results can be noticed on the temperature fluctuations for low Prandtl number fluids. Several boundary conditions are considered, namely isothermal, isoflux, and conjugate heat transfer. The impacts of the wall properties on the temperature statistics for conjugated heat transfer boundary conditions are deeply analysed.
Structure of Wall-Eddies at Very Large Reynolds Number--A Large-Scale PIV Study
NASA Astrophysics Data System (ADS)
Hommema, S. E.; Adrian, R. J.
2000-11-01
The results of an experiment performed in the first 5 m of the neutral atmospheric boundary layer are presented. Large-scale PIV measurements (up to 2 m × 2 m field-of-view) were obtained in the streamwise / wall-normal plane of a very-large Reynolds number (Re_θ > 10^6, based on momentum thickness and freestream velocity), flat-plate, zero-pressure-gradient boundary layer. Measurements were obtained at the SLTEST facility in the U.S. Army's Dugway Proving Grounds. Coherent packets of ramp-like structures with downstream inclination are observed and show a remarkable resemblance to those observed in typical laboratory-scale experiments at far lower Reynolds number. The results are interpreted in terms of a vortex packet paradigm(Adrian, R.J., C.D. Meinhart, and C.D. Tomkins, Vortex organization in the outer region of the turbulent boundary layer, to appear in J. Fluid Mech., 2000.) and begin to extend the model to high Reynolds numbers of technological importance. Additional results obtained during periods of non-neutral atmospheric stability are contrasted with those of the canonical neutral boundary layer. Sample smoke visualization images (3 m × 15 m field-of-view) are available online from the author.
Large-magnitude transient strain accumulation on the Blackwater fault, Eastern California shear zone
NASA Astrophysics Data System (ADS)
Oskin, Michael; Iriondo, Alex
2004-04-01
We investigate the Quaternary slip rate for the Blackwater fault, Eastern California shear zone, through mapping and geochronology of offset volcanic rocks. Basalt flows of the Black Mountains support the presence of faulting at 3.77 ± 0.11 Ma, 1.8 ± 0.1 km of subsequent slip, and a well-constrained long-term slip rate of 0.49 ± 0.04 mm/yr. Total slip diminishes northward, evidenced by a 0.3 1.8 km offset of a 7.23 ± 1.07 Ma dacite flow in the Black Hills and fault termination in the Lava Mountains, 5 km short of the Garlock fault. Slow long-term slip rate together with sparse evidence for Holocene rupture contradict predictions of rapid slip rate from tectonic geodesy. These results support the conclusion that as much as 95% of geodetic strain accumulation across the Blackwater fault, and thus from 1 to 6 mm/yr of geodetic strain measured across the Eastern California shear zone, is a transitory phenomenon. Discrepant geologic and geodetic results may indicate an increased near-term seismic hazard, but merit caution for interpretation of fault slip rates from geodesy alone.
NASA Astrophysics Data System (ADS)
Gonnermann, H. M.; Jellinek, M. A.; Richards, M. A.; Manga, M.
2001-12-01
We present results from a boundary-layer analysis and laboratory experiments aimed at understanding the effects of an imposed large-scale circulation on thermal convection at high-Rayleigh number (106 <= Ra <= 109) in a fluid with a strongly temperature-dependent viscosity. The ultimate goal of this work is to better understand the effect of plate-scale mantle flow on heat flux from the core-mantle boundary (CMB) and on the dynamics of plume formation at the CMB. We have developed a boundary-layer analysis that predicts heat flux from a hot surface as a function of imposed large-scale velocity, horizontal position along the surface, and viscosity ratio between the hot boundary-layer fluid and cold ambient fluid. In addition, we have examined how the large-scale flow modulates the formation and ascent of plume instabilities from the hot thermal boundary layer. Our theoretical analysis was complemented by lab experiments. In these experiments a layer of corn syrup was heated from below, while a large-scale flow was induced in the fluid above the hot boundary. Our results show that at low velocities, the imposed flow has a negligible effect on heat flux and development of the thermal boundary layer. At intermediate imposed velocities, boundary-layer instabilities, as well as ascending plumes are advected laterally by the imposed flow. In this case both large-scale flow and plumes carry heat from the hot boundary. At large imposed velocities a significant part of the hot boundary-layer fluid is advected laterally. As a consequence, the boundary layer becomes thinned and instabilities that generate plumes are suppressed. At this point the heat flux from the boundary is carried predominantly by the imposed flow. Thermal boundary layer thickness and heat flux from the hot boundary depend on the viscosity ratio between hot boundary layer fluid and ambient fluid, the Rayleigh number and the Peclet number of the flow. For a given Rayleigh number and viscosity ratio, boundary
Lu, T H; Lin, Y C; Liang, H C; Huang, Y J; Chen, Y F; Huang, K F
2010-02-01
We investigate the lasing modes in large-Fresnel-number laser systems with astigmatism effects. Experimental results reveal that numerous lasing modes are concentrated on exotic patterns corresponding to intriguing geometries. We theoretically use the quantum operator algebra to construct the wave representation for manifesting the origin of the localized wave patterns. PMID:20125716
Technology Transfer Automated Retrieval System (TEKTRAN)
Canopy reflectance indices have been used to monitor plant growth and estimate yields in many field crops. Little is known if canopy reflectance of sugarcane (a complex hybrid of Saccharum spp.) can be used to estimate growth and yield potential across large numbers of genotypes (clones) in the earl...
Infants Use Different Mechanisms to Make Small and Large Number Ordinal Judgments
ERIC Educational Resources Information Center
vanMarle, Kristy
2013-01-01
Previous research has shown indirectly that infants may use two different mechanisms-an object tracking system and an analog magnitude mechanism--to represent small (less than 4) and large (greater than or equal to 4) numbers of objects, respectively. The current study directly tested this hypothesis in an ordinal choice task by presenting 10- to…
Coherent large-scale structures in high Reynolds number supersonic jets
NASA Technical Reports Server (NTRS)
Lepicovsky, J.; Ahuja, K. K.; Brown, W. H.; Burrin, R. H.
1985-01-01
The flow structure of a 50.8 mm (2 in) diameter jet operated at a full expanded Mach number of 1.37, with Reynolds numbers in the range 1.7 to 2.35 million, was examined for the first 20 jet diameters. To facilitate the study of the large scale structure, and determine any coherence, a discrete tone acoustic excitation method was used. Phase locked flow visualization as well as laser velocimeter quantitative measurements were made. The main conclusions derived from this study are: (1) large scale coherent like turbulence structures do exist in large Reynolds number supersonic jets, and they prevail even beyond the potential core; (2) the most preferential Strouhal number for these structures is in the vicinity of 0.4; and (3) quantitatively, the peak amplitudes of these structures are rather low, and are about 1% of the jet exit velocity. Finally, since a number of unique problems related to LV measurements in supersonic jets were encountered, a summary of these problems and lessons learned therefrom are also reported.
Similarities between 2D and 3D convection for large Prandtl number
NASA Astrophysics Data System (ADS)
Pandey, Ambrish; Verma, Mahendra K.; Chatterjee, Anando G.; Dutta, Biplab
2016-06-01
Using direct numerical simulations of Rayleigh-B\\'{e}nard convection (RBC), we perform a comparative study of the spectra and fluxes of energy and entropy, and the scaling of large-scale quantities for large and infinite Prandtl numbers in two (2D) and three (3D) dimensions. We observe close similarities between the 2D and 3D RBC, in particular the kinetic energy spectrum $E_u(k) \\sim k^{-13/3}$, and the entropy spectrum exhibits a dual branch with a dominant $k^{-2}$ spectrum. We showed that the dominant Fourier modes in the 2D and 3D flows are very close. Consequently, the 3D RBC is quasi two-dimensional, which is the reason for the similarities between the 2D and 3D RBC for large- and infinite Prandtl numbers.
Wall-modeling for large-eddy simulation of high Reynolds number supersonic flows
NASA Astrophysics Data System (ADS)
Kawai, Soshi; Larsson, Johan; Lele, Sanjiva
2010-11-01
We present an idea of approximate wall-boundary-condition approach with dynamic procedure for large-eddy simulation of Mach 3 supersonic turbulent boundary layer at various Reynolds numbers (Reδ=2 x10^4, 10^5 and 10^6) on a flat plate. This wall-model is the extension of previous work by Wang and Moin [Phys. Fluid, 14, 2043 (2002)] for incompressible flows to compressible flows. We note that the present study is both the first extension of the dynamic concept to compressible flows and also the first test at high Reynolds number flows. The present study also revisits the issue of numerical errors near wall-region on outer-layer coarse LES mesh. The numerical results are compared with wall-resolved LES data (at low Reynolds number case) and available experimental data (at high Reynolds number case).
LEBU drag reduction in high Reynolds number boundary layers. [Large Eddy Break-Up
NASA Technical Reports Server (NTRS)
Anders, J. B.
1989-01-01
Conventional and inverted, outer-layer leading-edge breakup devices (LEBUs) were water tunnel tested on an axisymmetric body over the Re number range from 380,000 to 3.8 million. Test results indicate a sharp degradation of the LEBUs' drag-reduction mechanism with increasing Re number. The most likely result of this degradation is a decoupling of the inner and outer scales at higher Re numbers; due to this decoupling, the breakup of the large structures by outer-layer devices has minimal influence on the near-wall, shear-producing scales. This suggests that smaller devices, closer to the walls, may be required for operation at elevated Re numbers.
Indirect interband transition induced by optical near fields with large wave numbers
NASA Astrophysics Data System (ADS)
Yamaguchi, Maiku; Nobusada, Katsuyuki
2016-05-01
Optical near fields (ONFs) have Fourier components with large wave numbers that are two or three orders of magnitude larger than those of far-field propagating light owing to their nonuniformity in space. By utilizing these large wave numbers, the ONF is expected to induce an indirect interband transition between Bloch states having different wave numbers and directly generate an electron-hole pair without electron-phonon coupling. We perform time-dependent dynamics calculations of a one-dimensional periodic potential with an indirect band-gap structure and demonstrate that the ONF definitely induces an indirect interband transition. Instead of using the general Bloch boundary condition, which is usually imposed in conventional band structure calculations, we adopt an alternative boundary condition, the Born-von Kármán boundary condition, to appropriately treat indirect interband transitions. The calculated absorption spectra for the far-field and ONF excitations show different absorption edges and spectral patterns. We argue that this difference can be experimentally measured as evidence of the effects of the large wave numbers of the ONF.
Large-scale magnetic fields at high Reynolds numbers in magnetohydrodynamic simulations
NASA Astrophysics Data System (ADS)
Hotta, H.; Rempel, M.; Yokoyama, T.
2016-03-01
The 11-year solar magnetic cycle shows a high degree of coherence in spite of the turbulent nature of the solar convection zone. It has been found in recent high-resolution magnetohydrodynamics simulations that the maintenance of a large-scale coherent magnetic field is difficult with small viscosity and magnetic diffusivity (≲1012square centimenters per second). We reproduced previous findings that indicate a reduction of the energy in the large-scale magnetic field for lower diffusivities and demonstrate the recovery of the global-scale magnetic field using unprecedentedly high resolution. We found an efficient small-scale dynamo that suppresses small-scale flows, which mimics the properties of large diffusivity. As a result, the global-scale magnetic field is maintained even in the regime of small diffusivities—that is, large Reynolds numbers.
Large-scale magnetic fields at high Reynolds numbers in magnetohydrodynamic simulations.
Hotta, H; Rempel, M; Yokoyama, T
2016-03-25
The 11-year solar magnetic cycle shows a high degree of coherence in spite of the turbulent nature of the solar convection zone. It has been found in recent high-resolution magnetohydrodynamics simulations that the maintenance of a large-scale coherent magnetic field is difficult with small viscosity and magnetic diffusivity (≲10 (12) square centimenters per second). We reproduced previous findings that indicate a reduction of the energy in the large-scale magnetic field for lower diffusivities and demonstrate the recovery of the global-scale magnetic field using unprecedentedly high resolution. We found an efficient small-scale dynamo that suppresses small-scale flows, which mimics the properties of large diffusivity. As a result, the global-scale magnetic field is maintained even in the regime of small diffusivities-that is, large Reynolds numbers. PMID:27013727
Large deviations of the shifted index number in the Gaussian ensemble
NASA Astrophysics Data System (ADS)
Pérez Castillo, Isaac
2016-06-01
We show that, using the Coulomb fluid approach, we are able to derive a rate function \\Psi(c,x) of two variables that captures: (i) the large deviations of bulk eigenvalues; (ii) the large deviations of extreme eigenvalues (both left and right large deviations); (iii) the statistics of the fraction c of eigenvalues to the left of a position x. Thus, \\Psi(c,x) explains the full order statistics of the eigenvalues of large random Gaussian matrices as well as the statistics of the shifted index number. All our analytical findings are thoroughly compared with Monte Carlo simulations, obtaining excellent agreement. A summary of preliminary results has already been presented in Pérez Castillo (2014 Phys. Rev. E 90 040102) in the context of one-dimensional trapped spinless fermions in a harmonic potential.
Confined rotating convection with large Prandtl number: centrifugal effects on wall modes.
Curbelo, Jezabel; Lopez, Juan M; Mancho, Ana M; Marques, Francisco
2014-01-01
Thermal convection in a rotating cylinder with a radius-to-height aspect ratio of Γ=4 for fluids with large Prandtl number is studied numerically. Centrifugal buoyancy effects are investigated in a regime where the Coriolis force is relatively large and the onset of thermal convection is in the so-called wall modes regime, where pairs of hot and cold thermal plumes ascend and descend in the cylinder sidewall boundary layer, forming an essentially one-dimensional pattern characterized by the number of hot and cold plume pairs. In our numerical study, we use the physical parameters corresponding to aqueous mixtures of glycerine with mass concentration in the range of 60%-90% glycerine and a Rayleigh number range that extends from the threshold for wall modes up to values where the bulk fluid region is also convecting. The study shows that for the range of Rayleigh numbers considered, the local variations in viscosity due to temperature variation in the flow are negligible. However, the mean viscosity, which varies faster than exponentially with variations in the percentage of glycerine, leads to a faster than exponential increase in the Froude number for a fixed Coriolis force, and hence an enhancement of the centrifugal buoyancy effects with significant dynamical consequences, which are detailed. PMID:24580332
Large Cellular Inclusions Accumulate in Arabidopsis Roots Exposed to Low-Sulfur Conditions1[OPEN
Jackson, Terry L.; Baker, Ginger W.; Wilks, Floyd R.; Popov, Vladimir A.; Mathur, Jaideep; Benfey, Philip N.
2015-01-01
Sulfur is vital for primary and secondary metabolism in plant roots. To understand the molecular and morphogenetic changes associated with loss of this key macronutrient, we grew Arabidopsis (Arabidopsis thaliana) seedlings in low-sulfur conditions. These conditions induced a cascade of cellular events that converged to produce a profound intracellular phenotype defined by large cytoplasmic inclusions. The inclusions, termed low-sulfur Pox, show cell type- and developmental zone-specific localization. Transcriptome analysis suggested that low sulfur causes dysfunction of the glutathione/ascorbate cycle, which reduces flavonoids. Genetic and biochemical evidence indicated that low-sulfur Pox are the result of peroxidase-catalyzed oxidation of quercetin in roots grown under sulfur-depleted conditions. PMID:26099270
NASA Astrophysics Data System (ADS)
Nejadmalayeri, Alireza; Vezolainen, Alexei; Vasilyev, Oleg V.
2013-11-01
In view of the ongoing longtime pursuit of numerical approaches that can capture important flow physics of high Reynolds number flows with fewest degrees of freedom, two important wavelet-based multi-resolution schemes are thoroughly examined, namely, the Coherent Vortex Simulation (CVS) and the Stochastic Coherent Adaptive Large Eddy Simulation (SCALES) with constant and spatially/temporarily variable thresholding. Reynolds number scaling of active spatial modes for CVS and SCALES of linearly forced homogeneous turbulence at high Reynolds numbers is investigated in dynamic study for the first time. This dynamic computational complexity study demonstrates that wavelet-based methods can capture flow-physics while using substantially fewer degrees of freedom than both direct numerical simulation and marginally resolved LES with the same level of fidelity or turbulence resolution, defined as ratio of subgrid scale and the total dissipations. The study provides four important observations: (1) the linear Reynolds number scaling of energy containing structures at a fixed level of kinetic energy, (2) small, close to unity, fractal dimension for constant-threshold CVS and SCALES simulations, (3) constant, close to two, fractal dimension for constant-dissipation SCALES that is insensitive to the level of fidelity, and (4) faster than quadratic decay of the compression ratio as a function of turbulence resolution. The very promising slope for Reynolds number scaling of CVS and SCALES demonstrates the potential of the wavelet-based methodologies for hierarchical multiscale space/time adaptive variable fidelity simulations of high Reynolds number turbulent flows.
Investigation of Rossby-number similarity in the neutral boundary layer using large-eddy simulation
Ohmstede, W.D.; Cederwall, R.T.; Meyers, R.E.
1988-01-01
One special case of particular interest, especially to theoreticians, is the steady-state, horizontally homogeneous, autobarotropic (PLB), hereafter referred to as the neutral boundary layer (NBL). The NBL is in fact a 'rare' atmospheric phenomenon, generally associated with high-wind situations. Nevertheless, there is a disproportionate interest in this problem because Rossby-number similarity theory provides a sound approach for addressing this issue. Rossby-number similarity theory has rather wide acceptance, but because of the rarity of the 'true' NBL state, there remains an inadequate experimental database for quantifying constants associated with the Rossby-number similarity concept. Although it remains a controversial issue, it has been proposed that large-eddy simulation (LES) is an alternative to physical experimentation for obtaining basic atmospherc 'data'. The objective of the study reported here is to investigate Rossby-number similarity in the NBL using LES. Previous studies have not addressed Rossby-number similarity explicitly, although they made use of it in the interpretation of their results. The intent is to calculate several sets of NBL solutions that are ambiguous relative to the their respective Rossby numbers and compare the results for similarity, or the lack of it. 14 refs., 1 fig.
An autostereoscopic display with high resolution and large number of view zones
NASA Astrophysics Data System (ADS)
Chen, Wu-Li; Hsu, Wei-Liang; Tsai, Chao-Hsu; Wang, Chy-Lin; Wu, Chang-Shuo; Yang, Jinn-Cherng; Cheng, Shu-Chuan
2008-02-01
For a spatial-multiplexed 3D display, trade-off between resolution and number of view-zones are usually unavoidable due to the limited number of pixels on the screen. In this paper, we present a new autostereoscopic system, named as "integrated-screen system," to substantially increase the total number of pixels on the screen, which in turn increase both the resolution and number of view-zones. In the integrated-screen system, a large number of mini-projectors are arrayed and the images are tiled together without seams in between. For displaying 3D images, the lenticular screen with predesigned tilted angle is used for distributing different viewing zones. In order to achieve good performance, we design a brand-new projector with special lens set to meet the low-distortion requirement because the distortion of the image will induce serious crosstalk between view-zones. The proposed system has two advantages. One is the extensibility of the screen size. The size of the display can be chosen based on the applications we deal with, including the size of the projected pixel and the number of viewing zones. The other advantage is that the integrated-screen system provides projected pixels in great density to solve the major problem of the poor resolution that a lenticular-type 3D display has.
Viscous instabilities in the q-vortex at large swirl numbers
NASA Astrophysics Data System (ADS)
Fabre, David; Jacquin, Laurent
2002-11-01
This comunication deals with the temporal stability of the q-vortex trailing line vortex model. We describe a family of viscous instabilities existing in a range of parameters which is usually assumed to be stable, namely large swirl parameters (q>1.5) and large Reynolds numbers. These instabilities affect negative azimuthal wavenumbers (m < 0) and take the form of centre-modes (i.e. with a structure concentrated along the vortex centerline). They are related to a family of viscous modes described by Stewartson, Ng & Brown (1988) in swirling Poiseuille flow, and are the temporal counterparts of weakly amplified spatial modes recently computed by Olendraru & Sellier (2002). These instabilities are studied numerically using an original and highly accurate Chebyshev collocation method, which allows a mapping of the unstable regions up to Rey 10^6 and q 7. Our results indicate that in the limit of very large Reynolds numbers, trailing vortices are affected by this kind of instabilities whatever the value of the swirl number.
Effect of a large number of parties on the monogamy of quantum correlations
NASA Astrophysics Data System (ADS)
Kumar, Asutosh; Prabhu, R.; SenDe, Aditi; Sen, Ujjwal
2015-01-01
Monogamy is a nonclassical property that restricts the sharability of quantum correlation among the constituents of a multipartite quantum system. Quantum correlations may satisfy or violate monogamy for quantum states, which was tested mainly for three-qubit states. Here we establish a sufficient condition for monogamy of arbitrary quantum correlation measures of states of an arbitrary number of parties, using which and further numerical results, we obtain evidence for monogamy of measures such as distillable entanglement and relative entropy of entanglement, which are physically important but mathematically intractable, for almost all quantum states of a moderate number of parties. The result is generic and holds for a large class of quantum correlation measures. Nonetheless, we identify important zero Haar measure classes of pure states that remain nonmonogamous with respect to quantum discord and quantum work deficit, irrespective of the number of qubits.
Estimation of parameters in large offspring number models and ratios of coalescence times.
Eldon, Bjarki
2011-08-01
The ratio of singletons to the total number of segregating sites is used to estimate a reproduction parameter in a population model of large offspring numbers without having to jointly estimate the mutation rate. For neutral genetic variation, the ratio of singletons to the total number of segregating sites is equivalent to the ratio of total length of external branches to the total length of the gene genealogy. A multinomial maximum likelihood method that takes into account more frequency classes than just the singletons is developed to estimate the parameter of another large offspring number model. The performance of these methods with regard to sample size, mutation rate, and bias, is investigated by simulation. The expected value of the ratio of the total length of external branches to the total length of the whole tree is, using simulation, shown to decrease for the Kingman coalescent as sample size increases, but can increase or decrease, depending on parameter values, for Λ coalescents. Considering ratios of tree statistics, as opposed to considering lengths of various subtrees separately, can yield better insight into the dynamics of gene genealogies. PMID:21570995
Population Analysis of Large Copy Number Variants and Hotspots of Human Genetic Disease
Itsara, Andy; Cooper, Gregory M.; Baker, Carl; Girirajan, Santhosh; Li, Jun; Absher, Devin; Krauss, Ronald M.; Myers, Richard M.; Ridker, Paul M.; Chasman, Daniel I.; Mefford, Heather; Ying, Phyllis; Nickerson, Deborah A.; Eichler, Evan E.
2009-01-01
Copy number variants (CNVs) contribute to human genetic and phenotypic diversity. However, the distribution of larger CNVs in the general population remains largely unexplored. We identify large variants in ∼2500 individuals by using Illumina SNP data, with an emphasis on “hotspots” prone to recurrent mutations. We find variants larger than 500 kb in 5%–10% of individuals and variants greater than 1 Mb in 1%–2%. In contrast to previous studies, we find limited evidence for stratification of CNVs in geographically distinct human populations. Importantly, our sample size permits a robust distinction between truly rare and polymorphic but low-frequency copy number variation. We find that a significant fraction of individual CNVs larger than 100 kb are rare and that both gene density and size are strongly anticorrelated with allele frequency. Thus, although large CNVs commonly exist in normal individuals, which suggests that size alone can not be used as a predictor of pathogenicity, such variation is generally deleterious. Considering these observations, we combine our data with published CNVs from more than 12,000 individuals contrasting control and neurological disease collections. This analysis identifies known disease loci and highlights additional CNVs (e.g., 3q29, 16p12, and 15q25.2) for further investigation. This study provides one of the first analyses of large, rare (0.1%–1%) CNVs in the general population, with insights relevant to future analyses of genetic disease. PMID:19166990
A Simple Method for Estimating Interactions between a Treatment and a Large Number of Covariates
Tian, Lu; Alizadeh, Ash A; Gentles, Andrew J
2015-01-01
We consider a setting in which we have a treatment and a potentially large number of covariates for a set of observations, and wish to model their relationship with an outcome of interest. We propose a simple method for modeling interactions between the treatment and covariates. The idea is to modify the covariate in a simple way, and then fit a standard model using the modified covariates and no main effects. We show that coupled with an efficiency augmentation procedure, this method produces clinically meaningful estimators in a variety of settings. It can be useful for practicing personalized medicine: determining from a large set of biomarkers the subset of patients that can potentially benefit from a treatment. We apply the method to both simulated datasets and real trial data. The modified covariates idea can be used for other purposes, for example, large scale hypothesis testing for determining which of a set of covariates interact with a treatment variable. PMID:25729117
0{sup +} states in the large boson number limit of the Interacting Boson Approximation model
Bonatsos, Dennis; McCutchan, E. A.; Casten, R. F.
2008-11-11
Studies of the Interacting Boson Approximation (IBA) model for large boson numbers have been triggered by the discovery of shape/phase transitions between different limiting symmetries of the model. These transitions become sharper in the large boson number limit, revealing previously unnoticed regularities, which also survive to a large extent for finite boson numbers, corresponding to valence nucleon pairs in collective nuclei. It is shown that energies of 0{sub n}{sup +} states grow linearly with their ordinal number n in all three limiting symmetries of IBA [U(5), SU(3), and O(6)]. Furthermore, it is proved that the narrow transition region separating the symmetry triangle of the IBA into a spherical and a deformed region is described quite well by the degeneracies E(0{sub 2}{sup +}) = E(6{sub 1}{sup +}, E(0{sub 3}{sup +}) = E(10{sub 1}{sup +}), E(0{sub 4}{sup +}) = E(14{sub 1}{sup +}, while the energy ratio E(6{sub 1}{sup +})/E(0{sub 2}{sup +} turns out to be a simple, empirical, easy-to-measure effective order parameter, distinguishing between first- and second-order transitions. The energies of 0{sub n}{sup +} states near the point of the first order shape/phase transition between U(5) and SU(3) are shown to grow as n(n+3), in agreement with the rule dictated by the relevant critical point symmetries resulting in the framework of special solutions of the Bohr Hamiltonian. The underlying partial dynamical symmetries and quasi-dynamical symmetries are also discussed.
Large scale dynamics in a turbulent compressible rotor/stator cavity flow at high Reynolds number
NASA Astrophysics Data System (ADS)
Lachize, C.; Verhille, G.; Le Gal, P.
2016-08-01
This paper reports an experimental investigation of a turbulent flow confined within a rotor/stator cavity of aspect ratio close to unity at high Reynolds number. The experiments have been driven by changing both the rotation rate of the disk and the thermodynamical properties of the working fluid. This fluid is sulfur hexafluoride (SF6) whose physical properties are adjusted by imposing the operating temperature and the absolute pressure in a pressurized vessel, especially near the critical point of SF6 reached for T c = 45.58 ◦C, P c = 37.55 bar. This original set-up allows to obtain Reynolds numbers as high as 2 × 107 together with compressibility effects as the Mach number can reach 0.5. Pressure measurements reveal that the resulting fully turbulent flow shows both a direct and an inverse cascade as observed in rotating turbulence and in accordance with Kraichnan conjecture for 2D-turbulence. The spectra are however dominated by low-frequency peaks, which are subharmonics of the rotating disk frequency, involving large scale structures at small azimuthal wavenumbers. These modes appear for a Reynolds number around 105 and experience a transition at a critical Reynolds number Re c ≈ 106. Moreover they show an unexpected nonlinear behavior that we understand with the help of a low dimensional amplitude equations.
Estimating the effective Reynolds number in implicit large-eddy simulation.
Zhou, Ye; Grinstein, Fernando F; Wachtor, Adam J; Haines, Brian M
2014-01-01
In implicit large-eddy simulation (ILES), energy-containing large scales are resolved, and physics capturing numerics are used to spatially filter out unresolved scales and to implicitly model subgrid scale effects. From an applied perspective, it is highly desirable to estimate a characteristic Reynolds number (Re)-and therefore a relevant effective viscosity-so that the impact of resolution on predicted flow quantities and their macroscopic convergence can usefully be characterized. We argue in favor of obtaining robust Re estimates away from the smallest scales of the simulated flow-where numerically controlled dissipation takes place and propose a theoretical basis and framework to determine such measures. ILES examples include forced turbulence as a steady flow case, the Taylor-Green vortex to address transition and decaying turbulence, and simulations of a laser-driven reshock experiment illustrating a fairly complex turbulence problem of current practical interest. PMID:24580356
Impact factors for Reggeon-gluon transition in N=4 SYM with large number of colours
NASA Astrophysics Data System (ADS)
Fadin, V. S.; Fiore, R.
2014-06-01
We calculate impact factors for Reggeon-gluon transition in supersymmetric Yang-Mills theory with four supercharges at large number of colours Nc. In the next-to-leading order impact factors are not uniquely defined and must accord with BFKL kernels and energy scales. We obtain the impact factor corresponding to the kernel and the energy evolution parameter, which is invariant under Möbius transformation in momentum space, and show that it is also Möbius invariant up to terms taken into account in the BDS ansatz.
Diffractive imaging at large Fresnel number: Challenge of dynamic mesoscale imaging with hard x rays
NASA Astrophysics Data System (ADS)
Barber, John L.; Barnes, Cris W.; Sandberg, Richard L.; Sheffield, Richard L.
2014-05-01
Real materials have structure at both the atomic or crystalline scale as well as at interfaces and defects at the larger scale of grains. There is a need for the study of materials at the "mesoscale," the scale at which subgranular physical processes and intergranular organization couple to determine microstructure, crucially impacting constitutive response at the engineering macroscale. Diffractive imaging using photons that can penetrate multiple grains of material would be a transformative technique for the study of the performance of materials in dynamic extremes. Thicker samples imply higher energy photons of shorter wavelength, and imaging of multiple grains implies bigger spot sizes. Such imaging requires the use of future planned and proposed hard x-ray free electron lasers (such as the European XFEL) to provide both the spatial coherence transverse to the large spots and the peak brilliance to provide the short illumination times. The result is that the Fresnel number of the system becomes large and is no longer in the Fraunhofer far-field limit. The interrelated issues of diffractive imaging at large Fresnel number are analyzed, including proof that diffractive imaging is possible in this limit and estimates of the signal-to-noise possible. In addition, derivation of the heating rates for brilliant pulses of x rays are presented. The potential and limitations on multiple dynamic images are derived. This paper will present a study of x-ray interactions with materials in this new regime of spatially coherent but relatively large mesoscale spots at very hard energies. It should provide the theory and design background for the experiments and facilities required to control materials in extreme environments, in particular for the next generation of very-hard-x-ray free electron lasers.
Superposition of elliptic functions as solutions for a large number of nonlinear equations
Khare, Avinash; Saxena, Avadh
2014-03-15
For a large number of nonlinear equations, both discrete and continuum, we demonstrate a kind of linear superposition. We show that whenever a nonlinear equation admits solutions in terms of both Jacobi elliptic functions cn(x, m) and dn(x, m) with modulus m, then it also admits solutions in terms of their sum as well as difference. We have checked this in the case of several nonlinear equations such as the nonlinear Schrödinger equation, MKdV, a mixed KdV-MKdV system, a mixed quadratic-cubic nonlinear Schrödinger equation, the Ablowitz-Ladik equation, the saturable nonlinear Schrödinger equation, λϕ{sup 4}, the discrete MKdV as well as for several coupled field equations. Further, for a large number of nonlinear equations, we show that whenever a nonlinear equation admits a periodic solution in terms of dn{sup 2}(x, m), it also admits solutions in terms of dn {sup 2}(x,m)±√(m) cn (x,m) dn (x,m), even though cn(x, m)dn(x, m) is not a solution of these nonlinear equations. Finally, we also obtain superposed solutions of various forms for several coupled nonlinear equations.
Law of Large Numbers: the Theory, Applications and Technology-based Education
Dinov, Ivo D.; Christou, Nicolas; Gould, Robert
2011-01-01
Modern approaches for technology-based blended education utilize a variety of recently developed novel pedagogical, computational and network resources. Such attempts employ technology to deliver integrated, dynamically-linked, interactive-content and heterogeneous learning environments, which may improve student comprehension and information retention. In this paper, we describe one such innovative effort of using technological tools to expose students in probability and statistics courses to the theory, practice and usability of the Law of Large Numbers (LLN). We base our approach on integrating pedagogical instruments with the computational libraries developed by the Statistics Online Computational Resource (www.SOCR.ucla.edu). To achieve this merger we designed a new interactive Java applet and a corresponding demonstration activity that illustrate the concept and the applications of the LLN. The LLN applet and activity have common goals – to provide graphical representation of the LLN principle, build lasting student intuition and present the common misconceptions about the law of large numbers. Both the SOCR LLN applet and activity are freely available online to the community to test, validate and extend (Applet: http://socr.ucla.edu/htmls/exp/Coin_Toss_LLN_Experiment.html, and Activity: http://wiki.stat.ucla.edu/socr/index.php/SOCR_EduMaterials_Activities_LLN). PMID:21603584
Molecular replacement with a large number of molecules in the asymmetric unit
Jobichen, Chacko; Swaminathan, Kunchithapadam
2014-01-01
The exponential increase in protein structures deposited in the Protein Data Bank (PDB) has resulted in the elucidation of most, if not all, protein folds, thus making molecular replacement (MR) the most frequently used method for structure determination. A survey of the PDB shows that most of the structures determined by molecular replacement contain less than ten molecules in the asymmetric unit and that it is predominantly virus and ribosome structures that contain more than 20 molecules in the asymmetric unit. While the success of the MR method depends on several factors, such as the homology and the size of an input model, it is also a well known fact that this method can become significantly difficult in cases with a large number of molecules in the asymmetric unit, higher crystallographic symmetry and tight packing. In this paper, five representative structures containing 16–18 homomeric molecules in the asymmetric unit and the strategies that have been used to solve these structures are described. The difficulties faced and the lessons learned from these structure-determination efforts will be useful for selected and similar future situations with a large number of molecules in the asymmetric unit. PMID:25195913
Automated 3D trajectory measuring of large numbers of moving particles.
Wu, Hai Shan; Zhao, Qi; Zou, Danping; Chen, Yan Qiu
2011-04-11
Complex dynamics of natural particle systems, such as insect swarms, bird flocks, fish schools, has attracted great attention of scientists for years. Measuring 3D trajectory of each individual in a group is vital for quantitative study of their dynamic properties, yet such empirical data is rare mainly due to the challenges of maintaining the identities of large numbers of individuals with similar visual features and frequent occlusions. We here present an automatic and efficient algorithm to track 3D motion trajectories of large numbers of moving particles using two video cameras. Our method solves this problem by formulating it as three linear assignment problems (LAP). For each video sequence, the first LAP obtains 2D tracks of moving targets and is able to maintain target identities in the presence of occlusions; the second one matches the visually similar targets across two views via a novel technique named maximum epipolar co-motion length (MECL), which is not only able to effectively reduce matching ambiguity but also further diminish the influence of frequent occlusions; the last one links 3D track segments into complete trajectories via computing a globally optimal assignment based on temporal and kinematic cues. Experiment results on simulated particle swarms with various particle densities validated the accuracy and robustness of the proposed method. As real-world case, our method successfully acquired 3D flight paths of fruit fly (Drosophila melanogaster) group comprising hundreds of freely flying individuals. PMID:21503074
Fritz, H.; Barr, B.; Packham, A.; Melli, A.; Conrad, P.A.
2012-01-01
Two major obstacles to conducting studies with Toxoplasma gondii oocysts are the difficulty in reliably producing large numbers of this life stage and safety concerns because the oocyst is the most environmentally resistant stage of this zoonotic organism. Oocyst production requires oral infection of the definitive feline host with adequate numbers of T. gondii organisms to obtain unsporulated oocysts that are shed in the feces for 3-10 days after infection. Since the most successful and common mode of experimental infection of kittens with T. gondii is by ingestion of bradyzoite tissue cysts, the first step in successful oocyst production is to ensure a high bradyzoite tissue cyst burden in the brains of mice that can be used for the oral inoculum. We compared two methods for producing bradyzoite brain cysts in mice, by infecting them either orally or subcutaneously with oocysts. In both cases, oocysts derived from a low passage T. gondii Type II strain (M4) were used to infect eight-ten week-old Swiss Webster mice. First the number of bradyzoite cysts that were purified from infected mouse brains was compared. Then to evaluate the effect of the route of oocyst inoculation on tissue cyst distribution in mice, a second group of mice was infected with oocysts by one of each route and tissues were examined by histology. In separate experiments, brains from infected mice were used to infect kittens for oocyst production. Greater than 1.3 billion oocysts were isolated from the feces of two infected kittens in the first production and greater than 1.8 billion oocysts from three kittens in the second production. Our results demonstrate that oral delivery of oocysts to mice results in both higher cyst loads in the brain and greater cyst burdens in other tissues examined as compared to those of mice that received the same number of oocysts subcutaneously. The ultimate goal in producing large numbers of oocysts in kittens is to generate adequate amounts of starting material
Laws of Large Numbers and Langevin Approximations for Stochastic Neural Field Equations
2013-01-01
In this study, we consider limit theorems for microscopic stochastic models of neural fields. We show that the Wilson–Cowan equation can be obtained as the limit in uniform convergence on compacts in probability for a sequence of microscopic models when the number of neuron populations distributed in space and the number of neurons per population tend to infinity. This result also allows to obtain limits for qualitatively different stochastic convergence concepts, e.g., convergence in the mean. Further, we present a central limit theorem for the martingale part of the microscopic models which, suitably re-scaled, converges to a centred Gaussian process with independent increments. These two results provide the basis for presenting the neural field Langevin equation, a stochastic differential equation taking values in a Hilbert space, which is the infinite-dimensional analogue of the chemical Langevin equation in the present setting. On a technical level, we apply recently developed law of large numbers and central limit theorems for piecewise deterministic processes taking values in Hilbert spaces to a master equation formulation of stochastic neuronal network models. These theorems are valid for processes taking values in Hilbert spaces, and by this are able to incorporate spatial structures of the underlying model. Mathematics Subject Classification (2000): 60F05, 60J25, 60J75, 92C20. PMID:23343328
Large-eddy simulations of impinging jets at high Reynolds numbers
NASA Astrophysics Data System (ADS)
Wu, Wen; Piomelli, Ugo
2013-11-01
We have performed large-eddy simulations of an impinging jet with embedded azimuthal vortices. We used a hybrid approach in which the near-wall layer is modelled using the RANS equations with the Spalart-Allmaras model, while away from the wall Lagrangian-averaged dynamic eddy-viscosity modelled LES is used. This method allowed us to reach Reynolds numbers that would be prohibitively expensive for wall-resolving LES. First, we compared the results of the hybrid calculation with a wall-resolved one at moderate Reynolds number, Re = 66 , 000 (based on jet diameter and velocity). The mean velocity and Reynolds stresses were in good agreement between the simulations, and, in particular, the generation of secondary vorticity at the wall and its liftup were captured well. The simulation cost was reduced by 86%. We then carried out simulations at Re = 266 , 000 and 1.3 million. The effect of Reynolds number on vortex development will be discussed. Canada Research Chair in Computational Turbulence, HPCVL-Sun Microsystems Chair in Computational Science and Engineering.
Large Autosomal Copy-Number Differences within Unselected Monozygotic Twin Pairs are Rare.
McRae, Allan F; Visscher, Peter M; Montgomery, Grant W; Martin, Nicholas G
2015-02-01
Monozygotic (MZ) twins form an important system for the study of biological plasticity in humans. While MZ twins are generally considered to be genetically identical, a number of studies have emerged that have demonstrated copy-number differences within a twin pair, particularly in those discordant for disease. The rate of autosomal copy-number variation (CNV) discordance within MZ twin pairs was investigated using a population sample of 376 twin pairs genotyped on Illumina Human610-Quad arrays. After CNV calling using both QuantiSNP and PennCNV followed by manual annotation, only a single CNV difference was observed within the MZ twin pairs, being a 130 KB duplication of chromosome 5. Five other potential discordant CNV were called by the software, but excluded based on manual annotation of the regions. It is concluded that large CNV discordance is rare within MZ twin pairs, indicating that any CNV difference found within phenotypically discordant MZ twin pairs has a high probability of containing the causal gene(s) involved. PMID:25578400
The power of sensitivity analysis and thoughts on models with large numbers of parameters
Havlacek, William
2008-01-01
The regulatory systems that allow cells to adapt to their environments are exceedingly complex, and although we know a great deal about the intricate mechanistic details of many of these systems, our ability to make accurate predictions about their system-level behaviors is severely limited. We would like to make such predictions for a number of reasons. How can we reverse dysfunctional molecular changes of these systems that cause disease? More generally, how can we harness and direct cellular activities for beneficial purposes? Our ability to make accurate predictions about a system is also a measure ofour fundamental understanding of that system. As evidenced by our mastery of technological systems, a useful understanding ofa complex system can often be obtained through the development and analysis ofa mathematical model, but predictive modeling of cellular regulatory systems, which necessarily relies on quantitative experimentation, is still in its infancy. There is much that we need to learn before modeling for practical applications becomes routine. In particular, we need to address a number of issues surrounding the large number of parameters that are typically found in a model for a cellular regulatory system.
Support for the involvement of large copy number variants in the pathogenesis of schizophrenia
Kirov, George; Grozeva, Detelina; Norton, Nadine; Ivanov, Dobril; Mantripragada, Kiran K.; Holmans, Peter; Craddock, Nick; Owen, Michael J.; O'Donovan, Michael C.
2009-01-01
We investigated the involvement of rare (<1%) copy number variants (CNVs) in 471 cases of schizophrenia and 2792 controls that had been genotyped using the Affymetrix GeneChip® 500K Mapping Array. Large CNVs >1 Mb were 2.26 times more common in cases (P = 0.00027), with the effect coming mostly from deletions (odds ratio, OR = 4.53, P = 0.00013) although duplications were also more common (OR = 1.71, P = 0.04). Two large deletions were found in two cases each, but in no controls: a deletion at 22q11.2 known to be a susceptibility factor for schizophrenia and a deletion on 17p12, at 14.0–15.4 Mb. The latter is known to cause hereditary neuropathy with liability to pressure palsies. The same deletion was found in 6 of 4618 (0.13%) cases and 6 of 36 092 (0.017%) controls in the re-analysed data of two recent large CNV studies of schizophrenia (OR = 7.82, P = 0.001), with the combined significance level for all three studies achieving P = 5 × 10−5. One large duplication on 16p13.1, which has been previously implicated as a susceptibility factor for autism, was found in three cases and six controls (0.6% versus 0.2%, OR = 2.98, P = 0.13). We also provide the first support for a recently reported association between deletions at 15q11.2 and schizophrenia (P = 0.026). This study confirms the involvement of rare CNVs in the pathogenesis of schizophrenia and contributes to the growing list of specific CNVs that are implicated. PMID:19181681
Optimization of evaporative cooling towards a large number of Bose-Einstein-condensed atoms
Yamashita, Makoto; Mukai, Tetsuya; Mukai, Takaaki; Koashi, Masato; Mitsunaga, Masaharu; Imoto, Nobuyuki
2003-02-01
We study the optimization of evaporative cooling in trapped bosonic atoms on the basis of quantum kinetic theory of a Bose gas. The optimized cooling trajectory for {sup 87}Rb atoms indicates that the acceleration of evaporative cooling around the transition point of Bose-Einstein condensation is very effective against loss of trapped atoms caused by three-body recombination. The number of condensed atoms is largely enhanced by the optimization, more than two orders of magnitude in our present calculation using relevant experimental parameters, as compared with the typical value given by the conventional evaporative cooling where the frequency of radio-frequency magnetic field is swept exponentially. In addition to this optimized cooling, it is also shown that highly efficient evaporative cooling can be achieved by an initial exponential and then a rapid linear sweep of frequency.
Variation of froude number with discharge for large-gradient steams
Wahl, Kenneth L.
1993-01-01
Under chemical-control conditions, the Froude number (f) for a cross-section can be approximated as a function of the ratio R2/ 3/d 1/2 , where R is the hydraulic radius and d is the average depth. For cross sections where the ratio increases with increasing depth, F can also increase with depth Current-meter measurement data for 433 streamflow gaging stations in Colorado were reviewed, and 62 stations were identified at which F increases with depth of flow. Data for four streamflow gaging stations are presented. In some cases, F approaches 1 as the discharge approaches the magnitude of the median annual peak discharge. The data also indicate that few actual current meter measurement have been made at the large discharges where velocities can be supercritical.
NASA Technical Reports Server (NTRS)
Spyropoulos, Evangelos T.; Holmes, Bayard S.
1997-01-01
The dynamic subgrid-scale model is employed in large-eddy simulations of flow over a cylinder at a Reynolds number, based on the diameter of the cylinder, of 90,000. The Centric SPECTRUM(trademark) finite element solver is used for the analysis. The far field sound pressure is calculated from Lighthill-Curle's equation using the computed fluctuating pressure at the surface of the cylinder. The sound pressure level at a location 35 diameters away from the cylinder and at an angle of 90 deg with respect to the wake's downstream axis was found to have a peak value of approximately 110 db. Slightly smaller peak values were predicted at the 60 deg and 120 deg locations. A grid refinement study suggests that the dynamic model demands mesh refinement beyond that used here.
STARE Observations of a Pc 5 pulsation with large azimuthal wave number
Allan, W.; Poulter, E.M.; Nielsen, E.
1982-08-01
In recent years the STARE system has been used to analyze Pc5 pulsations of several different types. In this paper a detailed description of a new type of pulsation is given. The event described occurred during local magnetic afternoon; it had small amplitude (Vertical BarEVertical Bar< or approx. =5mV m/sup -1/ in the ionosphere), a period which varied from 220 to 385 s during the event, and a large azimuthal wave number (mapprox.35) which varied such as to keep the azimuthal phase velocity approximately constant for a given geomagnetic latitude; propagation was geomagnetic westward. When maped into the equatorial plane, the properties of the wave strongly suggest that the wave phase velocity was determined by hot proton drift motions near the equatorial plane. The observational results are compared with theoretical properties of the drift mirror instability. While the results do not contradict the predicted properties, it is felt that further theoretical development is required.
NASA Astrophysics Data System (ADS)
Ye, Peng-Cheng; Pan, Guang
2015-06-01
Due to the high speed of underwater vehicles, cavitation is generated inevitably along with the sound attenuation when the sound signal traverses through the cavity region around the underwater vehicle. The linear wave propagation is studied to obtain the influence of bubbly liquid on the acoustic wave propagation in the cavity region. The sound attenuation coefficient and the sound speed formula of the bubbly liquid are presented. Based on the sound attenuation coefficients with various vapor volume fractions, the attenuation of sound intensity is calculated under large cavitation number conditions. The result shows that the sound intensity attenuation is fairly small in a certain condition. Consequently, the intensity attenuation can be neglected in engineering. Project supported by the National Natural Science Foundation of China (Grant Nos. 51279165 and 51479170) and the National Defense Basic Scientific Research Program of China (Grant No. B2720133014).
Tail probabilities of extinction time in a large number of experimental populations.
Drake, John M
2014-05-01
Determining the distribution of population extinction times is a fundamental problem in theoretical population biology. In particular, the tail properties, patterns in the probability of long-term persistence, have not been studied. Further, until now there have been no experimental or observational data sets with which to empirically test the "rare event" predictions of the standard stochastic theory of extinction, which holds that extinction times should be exponentially distributed. I performed an experimental study of extinction in a large number of replicate (n = 1076) laboratory populations of the waterflea Daphnia pulicaria. Observed extinction time ranged from 1 to 1239 days. Statistical models supported the hypothesis of a power-law distribution over the exponential distribution and other alternatives. This pattern contradicts the notion that population extinction time has an exponential tail, questioning its ubiquitous use in theoretical ecology. It is also a rare instance of a data set that exhibits power-law scaling under appropriate statistical criteria. PMID:25000743
Allem, Jon-Patrick; Soto, Daniel; Baezconde-Garbanati, Lourdes; Unger, Jennifer
2014-01-01
Emerging adults (ages 18 to 25) who experience multiple role transitions in a short period of time may engage in hard drug use as a maladaptive coping strategy to avoid negative emotions from stress. Given the collectivistic values Hispanics encounter growing up, they may experience additional role transitions due to their group oriented cultural paradigm. This study examined whether those who experience many role transitions are at greater risk for hard drug use compared to those who experience few transitions among Hispanic emerging adults. Participants completed surveys indicating their hard drug use in emerging adulthood, role transitions in the past year of emerging adulthood, age, gender, and hard drug use in high school. Simulation analyses indicated that an increase in the number of role transitions, from 0 to 13, was associated with a 14% (95% CI, 4 to 29) higher probability of hard drug use. Specific role transitions were found to be associated with hard drug use, such as starting to date or experiencing a breakup. Intervention/prevention programs may benefit from acknowledging individual reactions to transitions in emerging adulthood, as these processes may be catalysts for personal growth where identities are consolidated, and decisions regarding hard drug use are formed. PMID:25715073
Large number of endemic equilibria for disease transmission models in patchy environment.
Knipl, D H; Röst, G
2014-12-01
We show that disease transmission models in a spatially heterogeneous environment can have a large number of coexisting endemic equilibria. A general compartmental model is considered to describe the spread of an infectious disease in a population distributed over several patches. For disconnected regions, many boundary equilibria may exist with mixed disease free and endemic components, but these steady states usually disappear in the presence of spatial dispersal. However, if backward bifurcations can occur in the regions, some partially endemic equilibria of the disconnected system move into the interior of the nonnegative cone and persist with the introduction of mobility between the patches. We provide a mathematical procedure that precisely describes in terms of the local reproduction numbers and the connectivity network of the patches, whether a steady state of the disconnected system is preserved or ceases to exist for low volumes of travel. Our results are illustrated on a patchy HIV transmission model with subthreshold endemic equilibria and backward bifurcation. We demonstrate the rich dynamical behavior (i.e., creation and destruction of steady states) and the presence of multiple stable endemic equilibria for various connection networks. PMID:25223233
Norris, Susan L.; Holmer, Haley K.; Burda, Brittany U.; Ogden, Lauren A.; Fu, Rongwei
2012-01-01
Background Conflict of interest (COI) of clinical practice guideline (CPG) sponsors and authors is an important potential source of bias in CPG development. The objectives of this study were to describe the COI policies for organizations currently producing a significant number of CPGs, and to determine if these policies meet 2011 Institute of Medicine (IOM) standards. Methodology/Principal Findings We identified organizations with five or more guidelines listed in the National Guideline Clearinghouse between January 1, 2009 and November 5, 2010. We obtained the COI policy for each organization from publicly accessible sources, most often the organization's website, and compared those polices to IOM standards related to COI. 37 organizations fulfilled our inclusion criteria, of which 17 (46%) had a COI policy directly related to CPGs. These COI policies varied widely with respect to types of COI addressed, from whom disclosures were collected, monetary thresholds for disclosure, approaches to management, and updating requirements. Not one organization's policy adhered to all seven of the IOM standards that were examined, and nine organizations did not meet a single one of the standards. Conclusions/Significance COI policies among organizations producing a large number of CPGs currently do not measure up to IOM standards related to COI disclosure and management. CPG developers need to make significant improvements in these policies and their implementation in order to optimize the quality and credibility of their guidelines. PMID:22629391
A New Approach to Reduce Number of Split Fields in Large Field IMRT
Lee, Chen-Chiao; Wu, Andrew; Garg, Madhur; Mutyala, Subhakar; Kalnicki, Shalom; Sayed, Gary; Mah, Dennis
2011-04-01
Intensity-modulated radiation therapy (IMRT) has been applied for treatments of primary head with neck nodes, lung with supraclavicular nodes, and high-risk prostate cancer with pelvis wall nodes, all of which require large fields. However, the design of the Varian multileaf collimator requires fields >14 cm in width to be split into 2 or more carriage movements. With the split-field technique, both the number of monitor units (MUs) and total treatment time are significantly increased. Although many different approaches have been investigated to reduce the MU, including introducing new leaf segmentation algorithms, none have resulted in widespread success. In addition, for most clinics, writing such algorithms is not a feasible solution, particularly with commercial treatment planning systems. We introduce a new approach that can minimize the number of split fields and reduce the total MUs, thereby reducing treatment time. The technique is demonstrated on the Eclipse planning system V7.3, but could be generalized to any other system.
Cosmonumerology, Cosmophysics, and the Large Numbers Hypothesis: British Cosmology in the 1930s
NASA Astrophysics Data System (ADS)
Durham, Ian
2001-04-01
A number of unorthodox cosmological models were developed in the 1930s, many by British theoreticians. Three of the most notable of these theories included Eddington's cosmonumerology, Milne's cosmophysics, and Dirac's large numbers hypothesis (LNH). Dirac's LNH was based partly on the other two and it has been argued that modern steady-state theories are based partly on Milne's cosmophysics. But what influenced Eddington and Milne? Both were products of the late Victorian education system in Britain and could conceivably have been influenced by Victorian thought which, in addition to its strict (though technically unoffical) social caste system, had a flair for the unusual. Victorianism was filled with a fascination for the occult and the supernatural, and science was not insulated from this trend (witness the Henry Slade trial in 1877). It is conceivable that the normally strict mentality of the scientific process in the minds of Eddington and Milne was affected, indirectly, by this trend for the unusual, possibly pushing them into thinking "outside the box" as it were. In addition, cosmonumerology and the LNH exhibit signs of Pythagorean and Aristotelian thought. It is the aim of this ongoing project at St. Andrews to determine the influences and characterize the relations existing in and within these and related theories.
Bichromatic Cooling used to Achieve a Large Number of Cold Atoms in a Compact Volume
NASA Astrophysics Data System (ADS)
Cubel Liebisch, Tara; Donley, Elizabeth; Blanshan, Eric; Kitching, John
2010-03-01
For cold atomic samples to be used in emerging technologies such as compact atomic clocks and sensors it is necessary to achieve small sample sizes with a large number of cold atoms. This is a challenge because in a magneto-optical trap (MOT) the number of cooled and trapped atoms scales as d^4, where d is the diameter of the laser beams (Gibble et.al.OL17, 526 (1992)). In a MOT the maximum radiation force is limited by spontaneous emission to hkγ/2. Bichromatic cooling first studied by Söding et.al. (PRL78,1420(1997)), takes advantage of stimulated emission and driven Rabi oscillations to cool atoms over a broad velocity range with forces >> hkγ/2. With the faster cooling rates, larger atom numbers can be obtained in very small cooling volumes. We report on preliminary results of cooling a thermal beam down to MOT capture velocities over distances of <1cm, our experimental set up, and theoretical results using our experimental parameters. We expect to be able to load a MOT with 1mm diameter beams with a factor of 100 more atoms than if loaded from a background vapor. With this atom sample we estimate we could achieve a clock stability of 1E-12 @ 1s with a Ramsey time of 4ms, a cycle time of 10ms, and a clock transition frequency of 6.8GHz. [0pt] We would like to acknowledge funding from NIST, DARPA, and NRC.
NASA Astrophysics Data System (ADS)
Figueroa, Aldo; Meunier, Patrice; Cuevas, Sergio; Villermaux, Emmanuel; Ramos, Eduardo
2014-01-01
We present a combination of experiment, theory, and modelling on laminar mixing at large Péclet number. The flow is produced by oscillating electromagnetic forces in a thin electrolytic fluid layer, leading to oscillating dipoles, quadrupoles, octopoles, and disordered flows. The numerical simulations are based on the Diffusive Strip Method (DSM) which was recently introduced (P. Meunier and E. Villermaux, "The diffusive strip method for scalar mixing in two-dimensions," J. Fluid Mech. 662, 134-172 (2010)) to solve the advection-diffusion problem by combining Lagrangian techniques and theoretical modelling of the diffusion. Numerical simulations obtained with the DSM are in reasonable agreement with quantitative dye visualization experiments of the scalar fields. A theoretical model based on log-normal Probability Density Functions (PDFs) of stretching factors, characteristic of homogeneous turbulence in the Batchelor regime, allows to predict the PDFs of scalar in agreement with numerical and experimental results. This model also indicates that the PDFs of scalar are asymptotically close to log-normal at late stages, except for the large concentration levels which correspond to low stretching factors.
Large eddy simulation of the FDA benchmark nozzle for a Reynolds number of 6500.
Janiga, Gábor
2014-04-01
This work investigates the flow in a benchmark nozzle model of an idealized medical device proposed by the FDA using computational fluid dynamics (CFD). It was in particular shown that a proper modeling of the transitional flow features is particularly challenging, leading to large discrepancies and inaccurate predictions from the different research groups using Reynolds-averaged Navier-Stokes (RANS) modeling. In spite of the relatively simple, axisymmetric computational geometry, the resulting turbulent flow is fairly complex and non-axisymmetric, in particular due to the sudden expansion. The resulting flow cannot be well predicted with simple modeling approaches. Due to the varying diameters and flow velocities encountered in the nozzle, different typical flow regions and regimes can be distinguished, from laminar to transitional and to weakly turbulent. The purpose of the present work is to re-examine the FDA-CFD benchmark nozzle model at a Reynolds number of 6500 using large eddy simulation (LES). The LES results are compared with published experimental data obtained by Particle Image Velocimetry (PIV) and an excellent agreement can be observed considering the temporally averaged flow velocities. Different flow regimes are characterized by computing the temporal energy spectra at different locations along the main axis. PMID:24561349
Two-position IR zoom lens with low f-number and large format
NASA Astrophysics Data System (ADS)
Howard, James W.; Garner, Michael S.; Freniere, Edward R.; Stern, Ronald D.; Armstrong, Karen L.
1992-09-01
We describe the optical, mechanical and servo designs for a motorized, two-FOV (field of view) IR objective lens for use in the 8 - 12 micrometers spectral band. The FOV is changed by moving lenses axially instead of the more traditional approach which is to add and remove lenses. The advantages of this approach include: simple mechanics, since a single mechanism can be used for both adjusting focus and changing FOV; only one lens group need be moved; no stow space is needed for removed lenses; and fewer total lenses are needed (four elements). The lens is used with a low-cost, uncooled focal plane array. This dictates relatively fast F- number, large image format (F/1.1, 7.8 degree(s) narrow FOV, 155-mm narrow-field focal length), and low cost. This combination of wide field and large collecting aperture pose a difficult optical design challenge. The lens meets a range of military environmental requirements including immersion in one meter of water. We describe how the requirements were met. We have fabricated and tested five lenses and we describe the assembly and testing process and present a summary of test results.
Optimum Guidance Law and Information Management for a Large Number of Formation Flying Spacecrafts
NASA Astrophysics Data System (ADS)
Tsuda, Yuichi; Nakasuka, Shinichi
In recent years, formation flying technique is recognized as one of the most important technologies for deep space and orbital missions that involve multiple spacecraft operations. Formation flying mission improves simultaneous observability over a wide area, redundancy and reconfigurability of the system with relatively small and low cost spacecrafts compared with the conventional single spacecraft mission. From the viewpoint of guidance and control, realizing formation flying mission usually requires tight maintenance and control of the relative distances, speeds and orientations between the member satellites. This paper studies a practical architecture for formation flight missions focusing mainly on guidance and control, and describes a new guidance algorithm for changing and keeping the relative positions and speeds of the satellites in formation. The resulting algorithm is suitable for onboard processing and gives the optimum impulsive trajectory for satellites flying closely around a certain reference orbit, that can be elliptic, parabolic or hyperbolic. Based on this guidance algorithm, this study introduces an information management methodology between the member spacecrafts which is suitable for a large formation flight architecture. Routing and multicast communication based on the wireless local area network technology are introduced. Some mathematical analyses and computer simulations will be shown in the presentation to reveal the feasibility of the proposed formation flight architecture, especially when a very large number of satellites join the formation.
Figueroa, Aldo; Meunier, Patrice; Villermaux, Emmanuel; Cuevas, Sergio; Ramos, Eduardo
2014-01-15
We present a combination of experiment, theory, and modelling on laminar mixing at large Péclet number. The flow is produced by oscillating electromagnetic forces in a thin electrolytic fluid layer, leading to oscillating dipoles, quadrupoles, octopoles, and disordered flows. The numerical simulations are based on the Diffusive Strip Method (DSM) which was recently introduced (P. Meunier and E. Villermaux, “The diffusive strip method for scalar mixing in two-dimensions,” J. Fluid Mech. 662, 134–172 (2010)) to solve the advection-diffusion problem by combining Lagrangian techniques and theoretical modelling of the diffusion. Numerical simulations obtained with the DSM are in reasonable agreement with quantitative dye visualization experiments of the scalar fields. A theoretical model based on log-normal Probability Density Functions (PDFs) of stretching factors, characteristic of homogeneous turbulence in the Batchelor regime, allows to predict the PDFs of scalar in agreement with numerical and experimental results. This model also indicates that the PDFs of scalar are asymptotically close to log-normal at late stages, except for the large concentration levels which correspond to low stretching factors.
MHC variability supports dog domestication from a large number of wolves: high diversity in Asia
Niskanen, A K; Hagström, E; Lohi, H; Ruokonen, M; Esparza-Salas, R; Aspi, J; Savolainen, P
2013-01-01
The process of dog domestication is still somewhat unresolved. Earlier studies indicate that domestic dogs from all over the world have a common origin in Asia. So far, major histocompatibility complex (MHC) diversity has not been studied in detail in Asian dogs, although high levels of genetic diversity are expected at the domestication locality. We sequenced the second exon of the canine MHC gene DLA–DRB1 from 128 Asian dogs and compared our data with a previously published large data set of MHC alleles, mostly from European dogs. Our results show that Asian dogs have a higher MHC diversity than European dogs. We also estimated that there is only a small probability that new alleles have arisen by mutation since domestication. Based on the assumption that all of the currently known 102 DLA–DRB1 alleles come from the founding wolf population, we simulated the number of founding wolf individuals. Our simulations indicate an effective population size of at least 500 founding wolves, suggesting that the founding wolf population was large or that backcrossing has taken place. PMID:23073392
Moreno-De-Luca, D; Sanders, S J; Willsey, A J; Mulle, J G; Lowe, J K; Geschwind, D H; State, M W; Martin, C L; Ledbetter, D H
2013-01-01
Copy number variants (CNVs) have a major role in the etiology of autism spectrum disorders (ASD), and several of these have reached statistical significance in case–control analyses. Nevertheless, current ASD cohorts are not large enough to detect very rare CNVs that may be causative or contributory (that is, risk alleles). Here, we use a tiered approach, in which clinically significant CNVs are first identified in large clinical cohorts of neurodevelopmental disorders (including but not specific to ASD), after which these CNVs are then systematically identified within well-characterized ASD cohorts. We focused our initial analysis on 48 recurrent CNVs (segmental duplication-mediated ‘hotspots') from 24 loci in 31 516 published clinical cases with neurodevelopmental disorders and 13 696 published controls, which yielded a total of 19 deletion CNVs and 11 duplication CNVs that reached statistical significance. We then investigated the overlap of these 30 CNVs in a combined sample of 3955 well-characterized ASD cases from three published studies. We identified 73 deleterious recurrent CNVs, including 36 deletions from 11 loci and 37 duplications from seven loci, for a frequency of 1 in 54; had we considered the ASD cohorts alone, only 58 CNVs from eight loci (24 deletions from three loci and 34 duplications from five loci) would have reached statistical significance. In conclusion, until there are sufficiently large ASD research cohorts with enough power to detect very rare causative or contributory CNVs, data from larger clinical cohorts can be used to infer the likely clinical significance of CNVs in ASD. PMID:23044707
Tang, Xiao-Jie; Peng, Cheng; Zhang, Jie; Cai, Yue; You, Xiao-Man; Kong, Fei; Yan, Hai-Gang; Wang, Guo-Xiang; Wang, Liang; Jin, Jie; Chen, Wei-Wei; Chen, Xin-Gang; Ma, Jing; Wang, Peng; Jiang, Ling; Zhang, Wen-Wei; Wan, Jian-Min
2016-08-01
ADP-glucose pyrophosphorylase (AGPase) controls a rate-limiting step in the starch biosynthetic pathway in higher plants. Here we isolated a shrunken rice mutant w24. Map-based cloning identified OsAGPL2, a large subunit of the cytosolic AGPase in rice endosperm, as the gene responsible for the w24 mutation. In addition to severe inhibition of starch synthesis and significant accumulation of sugar, the w24 endosperm showed obvious defects in compound granule formation and storage protein synthesis. The defect in OsAGPL2 enhanced the expression levels of the AGPase family. Meanwhile, the elevated activities of starch phosphorylase 1 and sucrose synthase in the w24 endosperm might possibly partly account for the residual starch content in the mutant seeds. Moreover, the expression of OsAGPL2 and its counterpart, OsAGPS2b, was highly coordinated in rice endosperm. Yeast two-hybrid and BiFC assays verified direct interactions between OsAGPL2 and OsAGPS2b as well as OsAGPL1 and OsAGPS1, supporting the model for spatiotemporal complex formation of AGPase isoforms in rice endosperm. Besides, our data provided no evidence for the self-binding of OsAGPS2b, implying that OsAGPS2b might not interact to form higher molecular mass aggregates in the absence of OsAGPL2. Therefore, the molecular mechanism of rice AGPase assembly might differ from that of Arabidopsis. PMID:27297991
NASA Astrophysics Data System (ADS)
Wen, Baole
Buoyancy-driven convection in fluid-saturated porous media is a key environmental and technological process, with applications ranging from carbon dioxide storage in terrestrial aquifers to the design of compact heat exchangers. Porous medium convection is also a paradigm for forced-dissipative infinite-dimensional dynamical systems, exhibiting spatiotemporally chaotic dynamics if not "true" turbulence. The objective of this dissertation research is to quantitatively characterize the dynamics and heat transport in two-dimensional horizontal and inclined porous medium convection between isothermal plane parallel boundaries at asymptotically large values of the Rayleigh number Ra by investigating the emergent, quasi-coherent flow. This investigation employs a complement of direct numerical simulations (DNS), secondary stability and dynamical systems theory, and variational analysis. The DNS confirm the remarkable tendency for the interior flow to self-organize into closely-spaced columnar plumes at sufficiently large Ra (up to Ra ≃ 105), with more complex spatiotemporal features being confined to boundary layers near the heated and cooled walls. The relatively simple form of the interior flow motivates investigation of unstable steady and time-periodic convective states at large Ra as a function of the domain aspect ratio L. To gain insight into the development of spatiotemporally chaotic convection, the (secondary) stability of these fully nonlinear states to small-amplitude disturbances is investigated using a spatial Floquet analysis. The results indicate that there exist two distinct modes of instability at large Ra: a bulk instability mode and a wall instability mode. The former usually is excited by long-wavelength disturbances and is generally much weaker than the latter. DNS, strategically initialized to investigate the fully nonlinear evolution of the most dangerous secondary instability modes, suggest that the (long time) mean inter-plume spacing in
HPC-Colony: Services and Interfaces to Aupport Systems With Very Large Numbers of Processors
Jones, T; Kale, L; Moreira, J; Mendes, C; Chakravorty, S; Tauferner, A; Inglett, T
2007-01-31
The HPC-Colony Project, a collaboration with Lawrence Livermore National Laboratory, the University of Illinois at Urbana-Champaign and IBM, is focused on services and interfaces for very large numbers of processors. Advances in parallel systems in the last decade have delivered phenomenal progress in the overall capability available to a single parallel application. Several systems with peak capability of over 100TF are already available and systems are expected to exceed 1PF within a few years. Despite these impressive advances in peak performance capability, the sustained performance of these systems continues to fall as a percentage of the peak capability. Initial analysis suggests that key architectural bottlenecks (in hardware and software) are responsible for the lower sustained performance and some architectural change of direction may be necessary to address the declining sustained performance. In this proposal we focus on addressing software architectural bottlenecks, in the areas of operating system and runtime systems. While the trend towards larger processor counts benefits application developers through more processing power, it also challenges application developers to harness ever-increasing numbers of processors for productive work. Much of the burden falls to operating systems and runtime systems that were originally designed for much smaller processor counts. Under the Colony project, we are researching and developing system software to enable general purpose operating and runtime systems for tens of thousands of processors. Difficulties in achieving a balanced partitioning and dynamically scheduling workloads can limit scaling for complex problems on large machines. Scientific simulations that span components of large machines require common operating system services, such as process scheduling, event notification, and job management to scale to large machines. Today, application programmers must explicitly manage these resources. We address
Generation of Large Numbers of Antigen-Expressing Human Dendritic Cells Using CD14-ML Technology
Imamura, Yuya; Haruta, Miwa; Tomita, Yusuke; Matsumura, Keiko; Ikeda, Tokunori; Yuno, Akira; Hirayama, Masatoshi; Nakayama, Hideki; Mizuta, Hiroshi; Nishimura, Yasuharu; Senju, Satoru
2016-01-01
We previously reported a method to expand human monocytes through lentivirus-mediated introduction of cMYC and BMI1, and we named the monocyte-derived proliferating cells, CD14-ML. CD14-ML differentiated into functional DC (CD14-ML-DC) upon addition of IL-4, resulting in the generation of a large number of DC. One drawback of this method was the extensive donor-dependent variation in proliferation efficiency. In the current study, we found that introduction of BCL2 or LYL1 along with cMYC and BMI1 was beneficial. Using the improved method, we obtained CD14-ML from all samples, regardless of whether the donors were healthy individuals or cancer patients. In vitro stimulation of peripheral blood T cells with CD14-ML-DC that were loaded with cancer antigen-derived peptides led to the establishment of CD4+ and CD8+ T cell lines that recognized the peptides. Since CD14-ML was propagated for more than 1 month, we could readily conduct genetic modification experiments. To generate CD14-ML-DC that expressed antigenic proteins, we introduced lentiviral antigen-expression vectors and subjected the cells to 2 weeks of culture for drug-selection and expansion. The resulting antigen-expressing CD14-ML-DC successfully induced CD8+ T cell lines that were reactive to CMVpp65 or MART1/MelanA, suggesting an application in vaccination therapy. Thus, this improved method enables the generation of a sufficient number of DC for vaccination therapy from a small amount of peripheral blood from cancer patients. Information on T cell epitopes is not necessary in vaccination with cancer antigen-expressing CD14-ML-DC; therefore, all patients, irrespective of HLA type, will benefit from anti-cancer therapy based on this technology. PMID:27050553
Baker, K L; Stappaerts, E A; Gavel, D; Tucker, J; Silva, D A; Wilks, S C; Olivier, S S; Olsen, J
2004-08-25
An adaptive optical system used to correct horizontal beam propagation paths has been demonstrated. This system utilizes an interferometric wave-front sensor and a large-actuator-number MEMS-based spatial light modulator to correct the aberrations incurred by the beam after propagation along the path. Horizontal path correction presents a severe challenge to adaptive optics systems due to the short atmospheric transverse coherence length and the high degree of scintillation incurred by laser propagation along these paths. Unlike wave-front sensors that detect phase gradients, however, the interferometric wave-front sensor measures the wrapped phase directly. Because the system operates with nearly monochromatic light and uses a segmented spatial light modulator, it does not require that the phase be unwrapped to provide a correction and it also does not require a global reconstruction of the wave-front to determine the phase as required by gradient detecting wave-front sensors. As a result, issues with branch points are eliminated. Because the atmospheric probe beam is mixed with a large amplitude reference beam, it can be made to operate in a photon noise limited regime making its performance relatively unaffected by scintillation. The MEMS-based spatial light modulator in the system contains 1024 pixels and is controlled to speeds in excess of 800 Hz, enabling its use for correction of horizontal path beam propagation. In this article results are shown of both atmospheric characterization with the system and open loop horizontal path correction of a 1.53 micron laser by the system. To date Strehl ratios of greater than 0.5 have been achieved.
Historical changes in the annual number of large floods in North America and Europe
NASA Astrophysics Data System (ADS)
Hodgkins, G. A.; Whitfield, P. H.; Hannaford, J.; Burn, D. H.; Renard, B.; Stahl, K.; Fleig, A.; Madsen, H.; Mediero, L.; Korhonen, J.; Murphy, C.; Crochet, P.; Wilson, D.
2013-12-01
Many studies have analyzed historical changes in low magnitude floods, such as the annual peak flow, at a national or regional scale. However, the river basins used have often been influenced by human alterations such as reservoir regulation or urbanization. No known studies have analyzed changes in large floods (greater than 25-year return period) at a continental scale for minimally impacted basins. To fill this research gap, this study analyzed flood flows from reference hydrologic networks (RHNs) or RHN-like gauges in North America (United States and Canada) and Europe (United Kingdom, Ireland, France, Spain, Germany, Switzerland, Austria, Iceland, Norway, Denmark, Sweden, and Finland). RHNs are formally defined networks in several countries that comprise gauging stations with a natural or near-natural flow regime and provide good quality data. Selected RHN-like gauges were included following a major effort to ensure RHN-like status through consultation with local experts. Peak flows with recurrence intervals of 25, 50, and 100 years were estimated using consistent methods for over 1200 study gauges, and peak flows at each gauge that exceeded these flood thresholds in the last 40-100 years were compiled. Continental and regional trends over time in the annual number of large floods, with regions differentiated by type of hydrological regime (pluvial, nival, mixed), are being computed and will be presented at AGU. The unique dataset used for this study is an example of successful international collaboration on hydro-climatic data exchange, which is potentially a step towards establishing RHN or RHN-like networks on a global scale. Analysis of flows from such networks would make a valuable contribution to the understanding of historical global hydrological change and would help inform expected future hydrologic changes.
Technical note: Computing options for genetic evaluation with a large number of genetic markers.
Tsuruta, S; Misztal, I
2008-07-01
Two simulated data sets and one commercial data set were used to evaluate computing options for models in which the effects attributable to QTL were fit as covariables. The simulated data sets included records on 24,000 animals for 10 traits. Data sets 1 and 2 were simulated with low and high correlations among traits, respectively. The model included an overall mean, 160 covariables as effects attributable to QTL, the random animal genetic effect, and the random residual effect. A commercial data set included records on approximately 110,000 animals for 11 growth, reproduction, and other traits. The model included the effects usually fitted for these traits as well as 116 covariables as effects attributable to QTL; models including the number of covariables varied by trait. Initial computing was by the BLUP90IOD program, which applies iterations on data by using a preconditioned conjugate gradient algorithm with a diagonal preconditioner. Modifications included adding block preconditioners for effects attributable to QTL (BQ) and for traits (BT). With the simulated data sets and the original program, one-trait analyses without the covariables took 7 s, whereas the 10-trait analyses with the covariables took 15 min for a data set with low correlations and 1 h 40 m for a data set with high correlations. The BQ improved the convergence rate but increased the computing time. The BT decreased the computing time from 1.5 times (low correlations) to 7 times (high correlation) at a cost of greater memory requirements. For the commercial data and the complete model, computing took 10.3 h with the unmodified program and was reduced to 6 h with BT. Relative changes in computing time and convergence rate with the commercial data set were close to those of the simulated data set, with low correlations among the traits. The BQ decreased the number of rounds by less than expected. Genetic evaluation with a large number of effects attributable to QTL fit as covariables is
Space Situational Awareness of Large Numbers of Payloads From a Single Deployment
NASA Astrophysics Data System (ADS)
Segerman, A.; Byers, J.; Emmert, J.; Nicholas, A.
2014-09-01
The nearly simultaneous deployment of a large number of payloads from a single vehicle presents a new challenge for space object catalog maintenance and space situational awareness (SSA). Following two cubesat deployments last November, it took five weeks to catalog the resulting 64 orbits. The upcoming Kicksat mission will present an even greater SSA challenge, with its deployment of 128 chip-sized picosats. Although all of these deployments are in short-lived orbits, future deployments will inevitably occur at higher altitudes, with a longer term threat of collision with active spacecraft. With such deployments, individual scientific payload operators require rapid precise knowledge of their satellites' locations. Following the first November launch, the cataloguing did not initially associate a payload with each orbit, leaving this to the satellite operators. For short duration missions, the time required to identify an experiment's specific orbit may easily be a large fraction of the spacecraft's lifetime. For a Kicksat-type deployment, present tracking cannot collect enough observations to catalog each small object. The current approach is to treat the chip cloud as a single catalog object. However, the cloud dissipates into multiple subclouds and, ultimately, tiny groups of untrackable chips. One response to this challenge may be to mandate installation of a transponder on each spacecraft. Directional transponder transmission detections could be used as angle observations for orbit cataloguing. Of course, such an approach would only be employable with cooperative spacecraft. In other cases, a probabilistic association approach may be useful, with the goal being to establish the probability of an element being at a given point in space. This would permit more reliable assessment of the probability of collision of active spacecraft with any cloud element. This paper surveys the cataloguing challenges presented by large scale deployments of small spacecraft
A New Dynamic Accumulator for Batch Updates
NASA Astrophysics Data System (ADS)
Wang, Peishun; Wang, Huaxiong; Pieprzyk, Josef
A dynamic accumulator is an algorithm, which gathers together a large set of elements into a constant-size value such that for a given element accumulated, there is a witness confirming that the element was indeed included into the value, with a property that accumulated elements can be dynamically added and deleted into/from the original set such that the cost of an addition or deletion operation is independent of the number of accumulated elements. Although the first accumulator was presented ten years ago, there is still no standard formal definition of accumulators. In this paper, we generalize formal definitions for accumulators, formulate a security game for dynamic accumulators so-called Chosen Element Attack (CEA), and propose a new dynamic accumulator for batch updates based on the Paillier cryptosystem. Our construction makes a batch of update operations at unit cost. We prove its security under the extended strong RSA (es-RSA) assumption.
An evidential approach to problem solving when a large number of knowledge systems is available
NASA Technical Reports Server (NTRS)
Dekorvin, Andre
1989-01-01
Some recent problems are no longer formulated in terms of imprecise facts, missing data or inadequate measuring devices. Instead, questions pertaining to knowledge and information itself arise and can be phrased independently of any particular area of knowledge. The problem considered in the present work is how to model a problem solver that is trying to find the answer to some query. The problem solver has access to a large number of knowledge systems that specialize in diverse features. In this context, feature means an indicator of what the possibilities for the answer are. The knowledge systems should not be accessed more than once, in order to have truly independent sources of information. Moreover, these systems are allowed to run in parallel. Since access might be expensive, it is necessary to construct a management policy for accessing these knowledge systems. To help in the access policy, some control knowledge systems are available. Control knowledge systems have knowledge about the performance parameters status of the knowledge systems. In order to carry out the double goal of estimating what units to access and to answer the given query, diverse pieces of evidence must be fused. The Dempster-Shafer Theory of Evidence is used to pool the knowledge bases.
Dynamic non-equilibrium wall-modeling for large eddy simulation at high Reynolds numbers
NASA Astrophysics Data System (ADS)
Kawai, Soshi; Larsson, Johan
2013-01-01
A dynamic non-equilibrium wall-model for large-eddy simulation at arbitrarily high Reynolds numbers is proposed and validated on equilibrium boundary layers and a non-equilibrium shock/boundary-layer interaction problem. The proposed method builds on the prior non-equilibrium wall-models of Balaras et al. [AIAA J. 34, 1111-1119 (1996)], 10.2514/3.13200 and Wang and Moin [Phys. Fluids 14, 2043-2051 (2002)], 10.1063/1.1476668: the failure of these wall-models to accurately predict the skin friction in equilibrium boundary layers is shown and analyzed, and an improved wall-model that solves this issue is proposed. The improvement stems directly from reasoning about how the turbulence length scale changes with wall distance in the inertial sublayer, the grid resolution, and the resolution-characteristics of numerical methods. The proposed model yields accurate resolved turbulence, both in terms of structure and statistics for both the equilibrium and non-equilibrium flows without the use of ad hoc corrections. Crucially, the model accurately predicts the skin friction, something that existing non-equilibrium wall-models fail to do robustly.
Porous capsules with a large number of active sites: nucleation/growth under confined conditions.
Garai, Somenath; Rubčić, Mirta; Bögge, Hartmut; Gouzerh, Pierre; Müller, Achim
2015-03-01
This work deals with the generation of large numbers of active sites and with ensuing nucleation/ growth processes on the inside wall of the cavity of porous nanocapsules of the type (pentagon)12(linker)30≡{(Mo(VI))Mo(VI)5}12{Mo(V)2(ligand)}30. A first example refers to sulfur dioxide capture through displacement of acetate ligands, while the grafted sulfite ligands are able to trap {MoO3H}(+) units thereby forming unusual {(O2SO)3MoO3H}(5-) assemblies. A second example relates to the generation of open coordination sites through release of carbon dioxide upon mild acidification of a carbonate-type capsule. When the reaction is performed in the presence of heptamolybdate ions, MoO4(2-) ions enter the cavity where they bind to the inside wall while forming new types of polyoxomolybdate architectures, thereby extending the molybdenum oxide skeleton of the capsule. Parallels can be drawn with Mo-storage proteins and supported MoO3 catalysts, making the results relevant to molybdenum biochemistry and to catalysis. PMID:25653204
An automated search of O'Connell effect for Large Numbers of Eclipsing Binaries
NASA Astrophysics Data System (ADS)
Papageorgiou, A.; Kleftogiannis, G.; Christopoulou, P. E.
2013-09-01
The O'Connell effect in eclipsing binary systems (unequally high maxima) has stood for many decades as one of the most perplexing challenges in binary studies. So far, this simple asymmetry has not been convincingly explained, but most theories attribute the effect to dynamic phenomena such as migrating star-spots or swirling circumstellar gas and dust. Nevertheless there has been no clear demonstration of a correlation between the assumptions of any one theory and the morphology of physical parameters of binary systems that exhibit O'Connell effect. We have developed an automated program that characterizes the morphology of light curves by depth of both minima, height of both maxima and curvature outside the eclipses. In terms of programming it is being developed in FORTRAN and PYTHON. This project results from realization of two needs, both related to recent discoveries of large number of contact binaries. Thus the first need is of a simple method to obtain essential parameters for these systems, without the necessity of full light-curve synthesis solution. The second is a statistical one: we would like to extract information from light curves with the use of coefficients that describe the asymmetry in the light curve maxima and the overall shape in the growing observational data of eclipsing binaries (OGLE, ASAS, KEPLER, GAIA). Before applying the automated program several complications must be addressed, as eccentricity, quality of data with many outlying points, limitations to the classification method already applied.
Left-right symmetry and lepton number violation at the Large Hadron electron Collider
NASA Astrophysics Data System (ADS)
Lindner, Manfred; Queiroz, Farinaldo S.; Rodejohann, Werner; Yaguna, Carlos E.
2016-06-01
We show that the proposed Large Hadron electron Collider (LHeC) will provide an opportunity to search for left-right symmetry and establish lepton number violation, complementing current and planned searches based on LHC data and neutrinoless double beta decay. We consider several plausible configurations for the LHeC — including different electron energies and polarizations, as well as distinct values for the charge misidentification rate. Within left-right symmetric theories we determine the values of right-handed neutrino and gauge boson masses that could be tested at the LHeC after one, five and ten years of operation. Our results indicate that this collider might probe, via the Δ L = 2 signal e - p → e + jjj, Majorana neutrino masses up to 1 TeV and W R masses up to ˜ 6 .5 TeV. Interestingly, part of this parameter space is beyond the expected reach of the LHC and of future neutrinoless double beta decay experiments.
NASA Astrophysics Data System (ADS)
Nam, Y. S.; Blümel, R.
2015-10-01
Removing a single logical gate from a classical information processor renders this processor useless. This is not so for a quantum information processor. A large number of quantum gates may be removed without significantly affecting the processor's performance. In this paper, focusing on the quantum Fourier transform (QFT) and quantum adder, we show even more: Even if most of its gates are eliminated and the remaining gates are selected from a randomly generated set, the QFT, one of the most useful quantum processors, and the quantum adder, one of the most basic building blocks of a universal quantum computer, still operate with satisfactory success probability, comparable to that of a quantum computer constructed with perfect gates. We support these conclusions by first laying out a general analytical framework and then deriving analytical scaling relations, which are in excellent agreement with our numerical simulations. The demonstrated robustness of the QFT and quantum adder, to the point where randomly generated quantum gates take the place of the exact gates, is an important boon for the construction of quantum computers, since it shows that stringent gate error tolerances do not have to be met to obtain satisfactory performance of the corresponding quantum processors. Our analytical techniques are powerful enough to generate asymptotic scaling laws for any gate defect model of quantum information processors and we illustrate this point by explicitly computing asymptotic analytical scaling formulas for several other defect models as well.
UGT2B17 copy number gain in a large ankylosing spondylitis multiplex family
2013-01-01
Background The primary objective of this study is to identify novel copy number variations (CNVs) associated with familial ankylosing spondylitis (AS). A customized genome-wide microarray was designed to detect CNVs and applied to a multiplex AS family with six (6) affected family members. CNVs were detected using the built-in DNA analytics aberration detection method-2 (ADM-2) algorithm. Gene enrichment analysis was performed to observe the segregation. Subsequent validation was performed using real time quantitative fluorescence polymerase reaction (QF-PCR). The frequency of copy number variation for the UGT2B17 gene was then performed on two well-defined AS cohorts. Fisher exact test was performed to quantify the association. Results Our family-based analysis revealed ten gene-enriched CNVs that segregate with all six family members affected with AS. Based on the proposed function and the polymorphic nature of the UGT2B17 gene, the UGT2B17 gene CNV was selected for validation using real time QF-PCR with full concordance. The frequency of two copies of the UGT2B17 gene CNV was 0.41 in the Newfoundland AS cases and 0.35 in the Newfoundland controls (OR = 1.26(0.99-1.59); p < 0.05)), whereas the frequency of two (2) copies of the UGT2B17 gene CNV was 0.40 in the Alberta AS cases and 0.39 in the Alberta controls (OR = 1.05(95% CI: 0.83-1.33); p < 0.71)). Conclusions A genome-wide microarray interrogation of a large multiplex AS family revealed segregation of the UGT2B17 gene CNV among all affected family members. The association of the UGT2B17 CNV with AS is particularly interesting given the recent association of this CNV with osteoporosis and the proposed function as it encodes a key enzyme that inhibits androgens. However, two copies of the UGT2B17 gene CNV were only marginally significant in a uniplex AS cohort from Newfoundland but not in a uniplex AS cohort from Alberta. PMID:23927372
Large-scale fluctuations in the number density of galaxies in independent surveys of deep fields
NASA Astrophysics Data System (ADS)
Shirokov, S. I.; Lovyagin, N. Yu.; Baryshev, Yu. V.; Gorokhov, V. L.
2016-06-01
New arguments supporting the reality of large-scale fluctuations in the density of the visible matter in deep galaxy surveys are presented. A statistical analysis of the radial distributions of galaxies in the COSMOS and HDF-N deep fields is presented. Independent spectral and photometric surveys exist for each field, carried out in different wavelength ranges and using different observing methods. Catalogs of photometric redshifts in the optical (COSMOS-Zphot) and infrared (UltraVISTA) were used for the COSMOS field in the redshift interval 0.1 < z < 3.5, as well as the zCOSMOS (10kZ) spectroscopic survey and the XMM-COSMOS and ALHAMBRA-F4 photometric redshift surveys. The HDFN-Zphot and ALHAMBRA-F5 catalogs of photometric redshifts were used for the HDF-N field. The Pearson correlation coefficient for the fluctuations in the numbers of galaxies obtained for independent surveys of the same deep field reaches R = 0.70 ± 0.16. The presence of this positive correlation supports the reality of fluctuations in the density of visible matter with sizes of up to 1000 Mpc and amplitudes of up to 20% at redshifts z ~ 2. The absence of correlations between the fluctuations in different fields (the correlation coefficient between COSMOS and HDF-N is R = -0.20 ± 0.31) testifies to the independence of structures visible in different directions on the celestial sphere. This also indicates an absence of any influence from universal systematic errors (such as "spectral voids"), which could imitate the detection of correlated structures.
Investigating the evolution of Shared Socioeconomic Pathways with a large number of scenarios
NASA Astrophysics Data System (ADS)
Schweizer, V. J.; Guivarch, C.; Rozenberg, J.
2013-12-01
The new scenario framework for climate change research includes alternative possible trends for socioeconomic development called Shared Socioeconomic Pathways (SSPs). The SSPs bear some similarities to other scenarios used for global change research, but they also have important differences. Like the IPCC Special Report on Emissions Scenarios or the Millennium Ecosystem Assessment, SSPs are defined by a scenario logic consisting of two axes. However, these axes define SSPs with respect to their location in an outcome space for challenges to mitigation and to adaptation rather than by their drivers. Open questions for the SSPs include what their drivers are and how the time dimension could be interpreted with the outcomes space. We present a new analytical approach for addressing both questions by studying large numbers of scenarios produced by an integrated assessment model, IMACLIM-R. We systematically generated 432 scenarios and used the SSP framework to classify them by typology. We then analyzed them dynamically, tracing their evolution through the SSP challenges space at annual time steps over the period 2010-2090. Through this approach, we found that many scenarios do not remain fixed to a particular SSP domain; they drift from one domain to another. In papers describing the framework for new scenarios, SSPs are envisioned as hypothetical (counter-factual) reference scenarios that remain fixed in one domain over some time period of interest. However, we conclude that it may be important to also research scenarios that shift across SSP domains. This is relevant for another open question, which is what scenarios are important to explore given their consequences. Through a data mining technique, we uncovered prominent drivers for scenarios that shift across SSP domains. Scenarios with different challenges for adaptation and mitigation (that is, mitigation and adaptation challenges that are not co-varying) were found to be the least stable, and the following
Nonclassical light from a large number of independent single-photon emitters
Lachman, Lukáš; Slodička, Lukáš; Filip, Radim
2016-01-01
Nonclassical quantum effects gradually reach domains of physics of large systems previously considered as purely classical. We derive a hierarchy of operational criteria suitable for a reliable detection of nonclassicality of light from an arbitrarily large ensemble of independent single-photon emitters. We show, that such large ensemble can always emit nonclassical light without any phase reference and under realistic experimental conditions including incoherent background noise. The nonclassical light from the large ensemble of the emitters can be witnessed much better than light coming from a single or a few emitters. PMID:26813774
Nonclassical light from a large number of independent single-photon emitters.
Lachman, Lukáš; Slodička, Lukáš; Filip, Radim
2016-01-01
Nonclassical quantum effects gradually reach domains of physics of large systems previously considered as purely classical. We derive a hierarchy of operational criteria suitable for a reliable detection of nonclassicality of light from an arbitrarily large ensemble of independent single-photon emitters. We show, that such large ensemble can always emit nonclassical light without any phase reference and under realistic experimental conditions including incoherent background noise. The nonclassical light from the large ensemble of the emitters can be witnessed much better than light coming from a single or a few emitters. PMID:26813774
Kenneth Martin, Andrew; Robinson, Gail; Reutens, David; Mowry, Bryan
2014-12-30
Large (>500 Kb), rare (frequency <1%) deletions are associated with risk for schizophrenia. The aim of the study was to characterise patients with these deletions using measures of cognition, grey-matter volume and white-matter integrity. Patients with schizophrenia and large, rare deletions (SZ-del) (n=17) were assessed on a test of intelligence, the Wechsler Abbreviated Scale of Intelligence (WASI), and compared with age- and sex-matched schizophrenia patients without large, rare deletions (SZ-nodel) (n=65), and healthy controls (HCs) (n=50). Regional grey-matter differences were investigated using voxel-based morphometry (SZ-del=9; SZ-nodel=26; HC=19). White-matter integrity was assessed using fractional anisotropy (SZ-del=9; SZ-nodel=24; HC=15). Compared with schizophrenia patients without large, rare deletions, those with large, rare deletions had lower IQ; greater grey-matter volume in clusters with peaks in the left and right cerebellum, left hippocampus, and right rectal gyrus; and increased white-matter anisotropy in the body and genu of the corpus callosum. Compared with healthy controls, patients with large, rare deletions had reduced grey matter volume in the right calcarine gyrus. In sum, patients with large, rare deletions had structural profiles intermediate to those observed in healthy controls and schizophrenia patients without large, rare deletions, but had greater impairment in intelligence. PMID:25453991
Investigation of the Turbulent Bursting Period over a Very Large Reynolds Number Range
NASA Astrophysics Data System (ADS)
Arce-Larreta, Enrique; Metzger, Meredith
2008-11-01
The present study examines Reynolds number scaling of the average bursting period, Tb, over a Reynolds number range spanning three orders of magnitude, using hot-wire anemometry measurements from combined wind tunnel and field experiments. Wind tunnel data were obtained from the study of Klewicki and Falco (1990) at Reynolds numbers based on momentum thickness of Reθ=1010, 2870, 4850; while the field data were acquired at the Surface Layer Turbulence and Environmental Test (SLTEST) facility at Reθ=5x10^6. Ejection events were detected from streamwise velocity time series using the U-Level algorithm of Lu and Wilmarth (1973). Events appearing in close succession were grouped into multiple event bursts using a statistical iterative approach based on pattern clustering. Four different Reynolds number scalings of Tb were investigated, namely: inner, outer, mixed, and intermediate. Data reveal that, of these four types of scalings, the Taylor microscale performs the best in removing Reynolds number dependencies in Tb. In addition, the present data reveal that outer scaled values of Tb decrease by two orders of magnitude over the range of Reynolds numbers; while inner scaled values of Tb increase by one order of magnitude.
NASA Astrophysics Data System (ADS)
Miroshnichenko, E.; Kit, E.; Gelfgat, A. Yu.
2016-03-01
A parametric experimental study of the cold plume instability that appears in the large-Prandtl-number Czochralski melt flows is reported. The critical temperature difference (the critical Grashof number) and the frequency of appearing oscillations were measured for varying Prandtl numbers, aspect ratios of the melt, and crystal/crucible radii ratio. The measurements were carried out by two independent and fully non-intrusive experimental techniques. The results are reported as dimensional and dimensionless parametric dependences, and then are joined into relatively simple empirical relations showing how the critical Grashof number and the frequency of emerging oscillations depend on other parameters.
NASA Technical Reports Server (NTRS)
Groesbeck, D. E.; Huff, R. G.; Vonglahn, U. H.
1977-01-01
Small-scale circular, noncircular, single- and multi-element nozzles with flow areas as large as 122 sq cm were tested with cold airflow at exit Mach numbers from 0.28 to 1.15. The effects of multi-element nozzle shape and element spacing on jet Mach number decay were studied in an effort to reduce the noise caused by jet impingement on externally blown flap (EBF) STOL aircraft. The jet Mach number decay data are well represented by empirical relations. Jet spreading and Mach number decay contours are presented for all configurations tested.
Accumulate repeat accumulate codes
NASA Technical Reports Server (NTRS)
Abbasfar, Aliazam; Divsalar, Dariush; Yao, Kung
2004-01-01
In this paper we propose an innovative channel coding scheme called 'Accumulate Repeat Accumulate codes' (ARA). This class of codes can be viewed as serial turbo-like codes, or as a subclass of Low Density Parity Check (LDPC) codes, thus belief propagation can be used for iterative decoding of ARA codes on a graph. The structure of encoder for this class can be viewed as precoded Repeat Accumulate (RA) code or as precoded Irregular Repeat Accumulate (IRA) code, where simply an accumulator is chosen as a precoder. Thus ARA codes have simple, and very fast encoder structure when they representing LDPC codes. Based on density evolution for LDPC codes through some examples for ARA codes, we show that for maximum variable node degree 5 a minimum bit SNR as low as 0.08 dB from channel capacity for rate 1/2 can be achieved as the block size goes to infinity. Thus based on fixed low maximum variable node degree, its threshold outperforms not only the RA and IRA codes but also the best known LDPC codes with the dame maximum node degree. Furthermore by puncturing the accumulators any desired high rate codes close to code rate 1 can be obtained with thresholds that stay close to the channel capacity thresholds uniformly. Iterative decoding simulation results are provided. The ARA codes also have projected graph or protograph representation that allows for high speed decoder implementation.
Practical quantum metrology with large precision gains in the low-photon-number regime
NASA Astrophysics Data System (ADS)
Knott, P. A.; Proctor, T. J.; Hayes, A. J.; Cooling, J. P.; Dunningham, J. A.
2016-03-01
Quantum metrology exploits quantum correlations to make precise measurements with limited particle numbers. By utilizing inter- and intramode correlations in an optical interferometer, we find a state that combines entanglement and squeezing to give a sevenfold enhancement in the quantum Fisher information (QFI)—a metric related to the precision—over the shot-noise limit, for low photon numbers. Motivated by practicality we then look at the squeezed cat state, which has recently been made experimentally, and shows further precision gains over the shot-noise limit and a threefold improvement in the QFI over the optimal Gaussian state. We present a conceptually simple measurement scheme that saturates the QFI, and we demonstrate a robustness to loss for small photon numbers. The squeezed cat state can therefore give a significant precision enhancement in optical quantum metrology in practical and realistic conditions.
NASA Astrophysics Data System (ADS)
Xue, Qingju; Su, Xiaomei; Steinman, Alan D.; Cai, Yongjiu; Zhao, Yanyan; Xie, Liqiang
2016-08-01
Although there have been numerous studies on microcystin (MC) accumulation in aquatic organisms recently, the bioaccumulation of MCs in relatively small sized organisms, as well as potential influencing factors, has been rarely studied. Thus, in this study, we investigated the bioaccumulation of three MC congeners (-LR, -RR and -YR) in the chironomid larvae of Tanypus chinensis (an excellent food source for certain fishes), the potential sources of these MCs, and potentially relevant environmental parameters over the course of one year in Lake Taihu, China. MC concentrations in T. chinensis varied temporally with highest concentrations during the warmest months (except August 2013) and very low concentrations during the remaining months. Among the three potential MC sources, only intracellular MCs were significantly and positively correlated with MCs in T. chinensis. Although MC concentrations in T. chinensis significantly correlated with a series of physicochemical parameters of water column, cyanobacteria species explained the most variability of MC accumulation, with the rest primarily explained by extraMC-LR. These results indicated that ingestion of MC-producing algae of cyanobacteria accounted for most of the MC that accumulated in T. chinensis. The high MC concentrations in T. chinensis may pose a potential health threat to humans through trophic transfer.
Xue, Qingju; Su, Xiaomei; Steinman, Alan D; Cai, Yongjiu; Zhao, Yanyan; Xie, Liqiang
2016-01-01
Although there have been numerous studies on microcystin (MC) accumulation in aquatic organisms recently, the bioaccumulation of MCs in relatively small sized organisms, as well as potential influencing factors, has been rarely studied. Thus, in this study, we investigated the bioaccumulation of three MC congeners (-LR, -RR and -YR) in the chironomid larvae of Tanypus chinensis (an excellent food source for certain fishes), the potential sources of these MCs, and potentially relevant environmental parameters over the course of one year in Lake Taihu, China. MC concentrations in T. chinensis varied temporally with highest concentrations during the warmest months (except August 2013) and very low concentrations during the remaining months. Among the three potential MC sources, only intracellular MCs were significantly and positively correlated with MCs in T. chinensis. Although MC concentrations in T. chinensis significantly correlated with a series of physicochemical parameters of water column, cyanobacteria species explained the most variability of MC accumulation, with the rest primarily explained by extraMC-LR. These results indicated that ingestion of MC-producing algae of cyanobacteria accounted for most of the MC that accumulated in T. chinensis. The high MC concentrations in T. chinensis may pose a potential health threat to humans through trophic transfer. PMID:27499175
Xue, Qingju; Su, Xiaomei; Steinman, Alan D.; Cai, Yongjiu; Zhao, Yanyan; Xie, Liqiang
2016-01-01
Although there have been numerous studies on microcystin (MC) accumulation in aquatic organisms recently, the bioaccumulation of MCs in relatively small sized organisms, as well as potential influencing factors, has been rarely studied. Thus, in this study, we investigated the bioaccumulation of three MC congeners (-LR, -RR and -YR) in the chironomid larvae of Tanypus chinensis (an excellent food source for certain fishes), the potential sources of these MCs, and potentially relevant environmental parameters over the course of one year in Lake Taihu, China. MC concentrations in T. chinensis varied temporally with highest concentrations during the warmest months (except August 2013) and very low concentrations during the remaining months. Among the three potential MC sources, only intracellular MCs were significantly and positively correlated with MCs in T. chinensis. Although MC concentrations in T. chinensis significantly correlated with a series of physicochemical parameters of water column, cyanobacteria species explained the most variability of MC accumulation, with the rest primarily explained by extraMC-LR. These results indicated that ingestion of MC-producing algae of cyanobacteria accounted for most of the MC that accumulated in T. chinensis. The high MC concentrations in T. chinensis may pose a potential health threat to humans through trophic transfer. PMID:27499175
Large-Chern-number quantum anomalous Hall effect in thin-film topological crystalline insulators.
Fang, Chen; Gilbert, Matthew J; Bernevig, B Andrei
2014-01-31
We theoretically predict that thin-film topological crystalline insulators can host various quantum anomalous Hall phases when doped by ferromagnetically ordered dopants. Any Chern number between ±4 can, in principle, be reached as a result of the interplay between (a) the induced Zeeman field, depending on the magnetic doping concentration, (b) the structural distortion, either intrinsic or induced by a piezoelectric material through the proximity effect, and (c) the thickness of the thin film. We propose a heterostructure to realize quantum anomalous Hall phases with Chern numbers that can be tuned by electric fields. PMID:24580476
Distance graphs having large chromatic numbers and containing no cliques or cycles of a given size
Demekhin, Evgenii E; Raigorodskii, Andrei M; Rubanov, Oleg I
2013-04-30
It is established that there exist sequences of distance graphs G{sub n} subset of R{sup n}, with chromatic numbers which grow exponentially, but, at the same time, without cliques or cycles of a given size. Bibliography: 42 titles.
ERIC Educational Resources Information Center
Richardson, William H., Jr.
2006-01-01
Computational precision is sometimes given short shrift in a first programming course. Treating this topic requires discussing integer and floating-point number representations and inaccuracies that may result from their use. An example of a moderately simple programming problem from elementary statistics was examined. It forced students to…
Accelerated Modular Multiplication Algorithm of Large Word Length Numbers with a Fixed Module
NASA Astrophysics Data System (ADS)
Bardis, Nikolaos; Drigas, Athanasios; Markovskyy, Alexander; Vrettaros, John
A new algorithm is proposed for the software implementation of modular multiplication, which uses pre-computations with a constant module. The developed modular multiplication algorithm provides high performance in comparison with the already known algorithms, and is oriented at the variable value of the module, especially with the software implementation on micro controllers and smart cards with a small number of bits.
Characteristics of Turbulent Flow Past Passive Rectangular Cavity at Large Reynolds Numbers
NASA Astrophysics Data System (ADS)
Ezhil Kumar, Perumal Kumaresan; Mishra, Debi Prasad
2016-06-01
In the present investigation, turbulent flow past passive rectangular cavity is investigated numerically for four mainstream Reynolds numbers namely Re ms = 20,000-50,000. Validation study reveals that the numerical models used in the present investigation predicts the data close to the existing experimental results. Further attempts are made to bring out the flow structure in terms of velocity profile, velocity gradients, shear layer growth rate, and turbulence characteristics. Numerical results are analyzed to bring out the variation in the velocity profile at different axial locations within the cavity. Also, the velocity gradient, turbulence level at the shear layer and the reverse flow velocity in the cavity are found to be sensitive to the mainstream Reynolds number. Finally, the cavity drag is estimated and its relation to the pressure drop across the cavity is brought out. These results reveal the nature of interaction between the passive cavity flow and mainstream flow.
A comment on "bats killed in large numbers at United States wind energy facilities"
Huso, Manuela M.P.; Dalthorp, Dan
2014-01-01
Widespread reports of bat fatalities caused by wind turbines have raised concerns about the impacts of wind power development. Reliable estimates of the total number killed and the potential effects on populations are needed, but it is crucial that they be based on sound data. In a recent BioScience article, Hayes (2013) estimated that over 600,000 bats were killed at wind turbines in the United States in 2012. The scientific errors in the analysis are numerous, with the two most serious being that the included sites constituted a convenience sample, not a representative sample, and that the individual site estimates are derived from such different methodologies that they are inherently not comparable. This estimate is almost certainly inaccurate, but whether the actual number is much smaller, much larger, or about the same is uncertain. An accurate estimate of total bat fatality is not currently possible, given the shortcomings of the available data.
Production of large numbers of size-controlled tumor spheroids using microwell plates.
Razian, Golsa; Yu, Yang; Ungrin, Mark
2013-01-01
Tumor spheroids are increasingly recognized as an important in vitro model for the behavior of tumor cells in three dimensions. More physiologically relevant than conventional adherent-sheet cultures, they more accurately recapitulate the complexity and interactions present in real tumors. In order to harness this model to better assess tumor biology, or the efficacy of novel therapeutic agents, it is necessary to be able to generate spheroids reproducibly, in a controlled manner and in significant numbers. The AggreWell system consists of a high-density array of pyramid-shaped microwells, into which a suspension of single cells is centrifuged. The numbers of cells clustering at the bottom of each microwell, and the number and ratio of distinct cell types involved depend only on the properties of the suspension introduced by the experimenter. Thus, we are able to generate tumor spheroids of arbitrary size and composition without needing to modify the underlying platform technology. The hundreds of microwells per square centimeter of culture surface area in turn ensure that extremely high production levels may be attained via a straightforward, nonlabor-intensive process. We therefore expect that this protocol will be broadly useful to researchers in the tumor spheroid field. PMID:24300192
Sequencing-based large-scale genomics approaches with small numbers of isolated maize meiocytes
Dukowic-Schulze, Stefanie; Sundararajan, Anitha; Ramaraj, Thiruvarangan; Mudge, Joann; Chen, Changbin
2014-01-01
High-throughput sequencing has become the large-scale approach of choice to study global gene expression and the distribution of specific chromatin marks and features. However, the limited availability of large amounts of purified cells made it very challenging to apply sequencing-based techniques in plant meiosis research in the past. In this paper, we describe a method to isolate meiocytes from maize anthers and detailed protocols to successfully perform RNA-seq, smRNA-seq, H3K4me3-ChIP-seq, and DNA bisulfite conversion sequencing with 5000–30,000 isolated maize male meiotic cells. These methods can be adjusted for other flowering plant species as well. PMID:24611068
Optimized arrays for 2-D resistivity survey lines with a large number of electrodes
NASA Astrophysics Data System (ADS)
Loke, M. H.; Wilkinson, P. B.; Chambers, J. E.; Uhlemann, S. S.; Sorensen, J. P. R.
2015-01-01
Previous studies show that optimized arrays generated using the 'Compare R' method have significantly better resolution than conventional arrays. This method determines the optimum set of arrays by selecting those that give the maximum model resolution. The number of possible arrays (the comprehensive data set) increases with the fourth power of the number of electrodes. The optimization method faces practical limitations for 2-D survey lines with more than 60 electrodes where the number of possible arrays exceeds a million. Several techniques are proposed to reduce the calculation time for such survey lines. A single-precision version of the 'Compare R' algorithm using a new ranking function reduces the calculation time by two to eight times while providing results similar to the double-precision version. Recent improvements in computer GPU technology can reduce the calculation time by about seven times. The calculation time is reduced by half by using the fact that arrays that are symmetrical about the center of the line produce identical changes in the model resolution values. It is further reduced by more than thirty times by calculating the Sherman-Morrison update for all the possible two-electrode combinations, which are then used to calculate the model resolution values for the four-electrode arrays. The calculation time is reduced by more then ten times by using a subset of the comprehensive data set consisting of only symmetrical arrays. Tests with a synthetic model and field data set show that optimized arrays derived from this subset produce inversion models with differences of less than 10% from those derived using the full comprehensive data set. The optimized data sets produced models that are more accurate than the Wenner-Schlumberger array data sets in all the tests.
Large-Eddy Simulation of Conductive Flows at Low Magnetic Reynolds Number
NASA Technical Reports Server (NTRS)
Knaepen, B.; Moin, P.
2003-01-01
In this paper we study the LES method with dynamic procedure in the context of conductive flows subject to an applied external magnetic field at low magnetic Reynolds number R(sub m). These kind of flows are encountered in many industrial applications. For example, in the steel industry, applied magnetic fields can be used to damp turbulence in the casting process. In nuclear fusion devices (Tokamaks), liquid-lithium flows are used as coolant blankets and interact with the surrounding magnetic field that drives and confines the fusion plasma. Also, in experimental facilities investigating the dynamo effect, the flow consists of liquid-sodium for which the Prandtl number and, as a consequence, the magnetic Reynolds number is low. Our attention is focused here on the case of homogeneous (initially isotropic) decaying turbulence. The numerical simulations performed mimic the thought experiment described in Moffatt in which an initially homogeneous isotropic conductive flow is suddenly subjected to an applied magnetic field and freely decays without any forcing. Note that this flow was first studied numerically by Schumann. It is well known that in that case, extra damping of turbulence occurs due to the Joule effect and that the flow tends to become progressively independent of the coordinate along the direction of the magnetic field. Our comparison of filtered direct numerical simulation (DNS) predictions and LES predictions show that the dynamic Smagorinsky model enables one to capture successfully the flow with LES, and that it automatically incorporates the effect of the magnetic field on the turbulence. Our paper is organized as follows. In the next section we summarize the LES approach in the case of MHD turbulence at low R(sub m) and recall the definition of the dynamic Smagorinsky model. In Sec. 3 we describe the parameters of the numerical experiments performed and the code used. Section 4 is devoted to the comparison of filtered DNS results and LES results
NASA Technical Reports Server (NTRS)
Ji, H.; Burin, M.; Schartman, E.; Goodman, J.; Liu, W.
2006-01-01
Two plausible mechanisms have been proposed to explain rapid angular momentum transport during accretion processes in astrophysical disks: nonlinear hydrodynamic instabilities and magnetorotational instability (MRI). A laboratory experiment in a short Taylor-Couette flow geometry has been constructed in Princeton to study both mechanisms, with novel features for better controls of the boundary-driven secondary flows (Ekman circulation). Initial results on hydrodynamic stability have shown negligible angular momentum transport in Keplerian-like flows with Reynolds numbers approaching one million, casting strong doubt on the viability of nonlinear hydrodynamic instability as a source for accretion disk turbulence.
NASA Technical Reports Server (NTRS)
Eckert, E R G; Diaguila, A J
1955-01-01
Report presents the results of an investigation conducted to study free-convection heat transfer in a stationary vertical tube closed at the bottom. The walls of the tube were heated, and heated air in the tube was continuously replaced by fresh cool air at the top. The tube was designed to provide a gravitational field with Grashof numbers of a magnitude comparable with those generated by the centrifugal field in rotating-blade coolant passages (10(8) to 10(13)). Local heat-transfer coefficients in the turbulent-flow range and the temperature field within the fluid were obtained.
Using addition to solve large subtractions in the number domain up to 20.
Peters, Greet; De Smedt, Bert; Torbeyns, Joke; Ghesquière, Pol; Verschaffel, Lieven
2010-02-01
This study examined 25 university students' use of addition to solve large single-digit subtractions by contrasting performance in the standard subtraction format (12-9=.) and in the addition format (9+.=12). In particular, we investigated the effect of the relative size of the subtrahend on performance in both formats. We found a significant interaction between format, the magnitude of the subtrahend (S) compared to the difference (D) (S>D vs. S
Large Eddy Simulation of Airfoil Self-Noise at High Reynolds Number
NASA Astrophysics Data System (ADS)
Kocheemoolayil, Joseph; Lele, Sanjiva
2015-11-01
The trailing edge noise section (Category 1) of the Benchmark Problems for Airframe Noise Computations (BANC) workshop features five canonical problems. No first-principles based approach free of empiricism and tunable coefficients has successfully predicted trailing edge noise for the five configurations to date. Our simulations predict trailing edge noise accurately for all five configurations. The simulation database is described in detail, highlighting efforts undertaken to validate the results through systematic comparison with dedicated experiments and establish insensitivity to grid resolution, domain size, alleatory uncertainties such as the tripping mechanism used to force transition to turbulence and epistemic uncertainties such as models for unresolved near-wall turbulence. Ongoing efforts to extend the predictive capability to non-canonical configurations featuring flow separation are summarized. A novel, large-span calculation that predicts the flow past a wind turbine airfoil in deep stall with unprecedented accuracy is presented. The simulations predict airfoil noise in the near-stall regime accurately. While the post-stall noise predictions leave room for improvement, significant uncertainties in the experiment might preclude a fair comparison in this regime. We thank Cascade Technologies Inc. for providing access to the CharLES toolkit - a massively-parallel, unstructured large eddy simulation framework.
Ecological specialization and rarity indices estimated for a large number of plant species in France
Mobaied, Samira; Machon, Nathalie; Porcher, Emmanuelle
2015-01-01
The biological diversity of the Earth is being rapidly depleted due to the direct and indirect consequences of human activities. Specialist or rare species are generally thought to be more extinction prone than generalist or common species. Testing this assumption however requires that the rarity and ecological specialization of the species are quantified. Many indices have been developed to classify species as generalists vs. specialists or as rare vs. common, but large data sets are needed to calculate these indices. Here, we present a list of specialization and rarity values for more than 2800 plant species of continental France, which were computed from the large botanical and ecological dataset SOPHY. Three specialization indices were calculated using species co-occurrence data. All three indices are based on (dis)similarity among plant communities containing a focal species, quantified either as beta diversity in an additive (Fridley et al., 2007 [6]) or multiplicative (Zeleny, 2008 [15]) partitioning of diversity or as the multiple site similarity of Baselga et al. (2007) [1]. Species rarity was calculated as the inverse of a species occurrence. PMID:26217738
Electrically driving large magnetic Reynolds number flows on the Madison plasma dynamo experiment
NASA Astrophysics Data System (ADS)
Weisberg, David; Wallace, John; Peterson, Ethan; Endrezzi, Douglass; Forest, Cary B.; Desangles, Victor
2015-11-01
Electrically-driven plasma flows, predicted to excite a large-scale dynamo instability, have been generated in the Madison plasma dynamo experiment (MPDX), at the Wisconsin Plasma Astrophysics Laboratory. Numerical simulations show that certain topologies of these simply-connected flows may be optimal for creating a plasma dynamo and predict critical thresholds as low as Rmcrit =μ0 σLV = 250 . MPDX plasmas are shown to exceed this critical Rm , generating large (L = 1 . 4 m), warm (Te > 10 eV), unmagnetized (MA > 1) plasmas where Rm < 600 . Plasma flow is driven using ten thermally emissive LaB6 cathodes which generate a J × B torque in Helium plasmas. Detailed Mach probe measurements of plasma velocity for two flow topologies will be presented: edge-localized drive using the multi-cusp boundary field, and volumetric drive using an axial Helmholtz field. Radial velocity profiles show that edge-driven flow is established via ion viscosity but is limited by a volumetric neutral drag force (χ ~ 1 / (ντin)), and measurements of velocity shear compare favorably to Braginskii transport theory. Volumetric flow drive is shown to produce stronger velocity shear, and is characterized by the radial potential gradient as determined by global charge balance.
Large numbers of genetic variants considered to be pathogenic are common in asymptomatic individuals
Cassa, Christopher A.; Tong, Mark Y.; Jordan, Daniel M.
2013-01-01
It is now affordable to order clinically interpreted whole genome sequence reports from clinical laboratories. One major component of these reports is derived from the knowledge base of previously identified pathogenic variants, including research articles, locus specific and other databases. While over 150,000 such pathogenic variants have been identified, many of these were originally discovered in small cohort studies of affected individuals, so their applicability to asymptomatic populations is unclear. We analyzed the prevalence of a large set of pathogenic variants from the medical and scientific literature in a large set of asymptomatic individuals (N=1,092) and found 8.5% of these pathogenic variants in at least one individual. In the average individual in the 1000 Genomes Project, previously identified pathogenic variants occur on average 294 times (σ= 25.5) in homozygous form and 942 times (σ = 68.2) in heterozygous form. We also find that many of these pathogenic variants are frequently occurring: there are 3,744 variants with MAF >= 0.01 (4.6%) and 2,837 variants with MAF >= 0.05 (3.5%). This indicates that many of these variants may be erroneous findings or have lower penetrance than previously expected. PMID:23818451
Double large field stereoscopic PIV in a high Reynolds number turbulent boundary layer
NASA Astrophysics Data System (ADS)
Coudert, S.; Foucaut, J. M.; Kostas, J.; Stanislas, M.; Braud, P.; Fourment, C.; Delville, J.; Tutkun, M.; Mehdi, F.; Johansson, P.; George, W. K.
2011-01-01
An experiment on a flat plate turbulent boundary layer at high Reynolds number has been carried out in the Laboratoire de Mecanique de Lille (LML, UMR CNRS 8107) wind tunnel. This experiment was performed jointly with LEA (UMR CNRS 6609) in Poitiers (France) and Chalmers University of Technology (Sweden), in the frame of the WALLTURB European project. The simultaneous recording of 143 hot wires in one transverse plane and of two perpendicular stereoscopic PIV fields was performed successfully. The first SPIV plane is 1 cm upstream of the hot wire rake and the second is both orthogonal to the first one and to the wall. The first PIV results show a blockage effect which based on both statistical results (i.e. mean, RMS and spatial correlation) and a potential model does not seem to affect the turbulence organization.
Technology Transfer Automated Retrieval System (TEKTRAN)
Copy number variants (CNV) are large scale duplications or deletions of genomic sequence that are caused by a diverse set of molecular phenomena that are distinct from single nucleotide polymorphism (SNP) formation. Due to their different mechanisms of formation, CNVs are often difficult to track us...
Soya, Ryoko; Taguchi, Jyunichi; Nagakawa, Yuichi; Takahashi, Osamu; Sandoh, Norimasa; Hosokawa, Yuichi; Kasuya, Kazuhiko; Umeda, Naoki; Okamoto, Masato; Tsujitani, Shunichi; Tsuchida, Akihiko
2015-09-01
We hypothesized that a large number of circulating tumor cells(CTCs)may be isolated from samples obtained by using the leukapheresis procedures that are utilized to collect peripheral blood mononuclear cells for dendritic cell vaccine therapy. We utilized the CellSearch System to determine the number of CTCs in samples obtained by using leukapheresis in 7 patients with colorectal cancer, 5 patients with breast cancer, and 3 patients with gastric cancer. In all patients, a large number of CTCs were isolated. The mean number of CTCs per tumor was 17.1(range 10-34)in colorectal cancer, 10.0(range 2-27)in breast cancer, and 24.0(range 2-42)in gastric cancer. We succeeded in culturing the isolated CTCs from 7 patients with colorectal cancer, 5 patients with breast cancer, and 3 patients with gastric cancer. In conclusion, compared to conventional methods, a large number of CTCs can be obtained by using leukapheresis procedures. The molecular analyses of the CTCs isolated by using this method should be promising in the development of personalized cancer treatments. PMID:26469161
Unexpectedly large number of conserved noncoding regions within the ancestral chordate Hox cluster.
Pascual-Anaya, Juan; D'Aniello, Salvatore; Garcia-Fernàndez, Jordi
2008-12-01
The single amphioxus Hox cluster contains 15 genes and may well resemble the ancestral chordate Hox cluster. We have sequenced the Hox genomic complement of the European amphioxus Branchiostoma lanceolatum and compared it to the American species, Branchiostoma floridae, by phylogenetic footprinting to gain insights into the evolution of Hox gene regulation in chordates. We found that Hox intergenic regions are largely conserved between the two amphioxus species, especially in the case of genes located at the 3' of the cluster, a trend previously observed in vertebrates. We further compared the amphioxus Hox cluster with the human HoxA, HoxB, HoxC, and HoxD clusters, finding several conserved noncoding regions, both in intergenic and intronic regions. This suggests that the regulation of Hox genes is highly conserved across chordates, consistent with the similar Hox expression patterns in vertebrates and amphioxus. PMID:18791732
NASA Astrophysics Data System (ADS)
Rodrigues, Luiz Felippe S.; Opher, Reuven
2010-07-01
A smooth inflaton potential is generally assumed when calculating the primordial power spectrum, implicitly assuming that a very small oscillation in the inflaton potential creates a negligible change in the predicted halo mass function. We show that this is not true. We find that a small oscillating perturbation in the inflaton potential in the slow-roll regime can alter significantly the predicted number of small halos. A class of models derived from supergravity theories gives rise to inflaton potentials with a large number of steps and many trans-Planckian effects may generate oscillations in the primordial power spectrum. The potentials we study are the simple quadratic (chaotic inflation) potential with superimposed small oscillations for small field values. Without leaving the slow-roll regime, we find that for a wide choice of parameters, the predicted number of halos change appreciably. For the oscillations beginning in the 107-108M⊙ range, for example, we find that only a 5% change in the amplitude of the chaotic potential causes a 50% suppression of the number of halos for masses between 107-108M⊙ and an increase in the number of halos for masses <106M⊙ by factors ˜15-50. We suggest that this might be a solution to the problem of the lack of observed dwarf galaxies in the range 107-108M⊙. This might also be a solution to the reionization problem where a very large number of Population III stars in low mass halos are required.
Transient high-Rayleigh-number thermal convection with large viscosity variations
NASA Astrophysics Data System (ADS)
Davaille, Anne; Jaupart, Claude
1993-08-01
Results of laboratory studies of the characteristics of thermal convection in a fluid whose viscosity varies strongly with temperature are presented. The upper boundary of an isothermal layer of Golden Syrup is cooled rapidly and maintained at a fixed temperature. The fluid layer is insulated at the bottom and cools continuously. Rayleigh number calculated with the viscosity of the well-mixed interior are between 10 exp 6 and 10 exp 8, and viscosity contrasts are up to 10 exp 6. Thermal convection develops only in the lower part of the thermal boundary layer, and the upper part remains stagnant. At the onset of convection, the viscosity contrast across the unstable boundary layer has a value of about 3. In fully developed convection, this viscosity contrast is higher, with a typical value of 10. The heat flux through the top of the layer depends solely on local conditions in the unstable boundary layer. The magnitude of temperature fluctuations and the thickness of the stagnant lid are calculated to be in excellent agreement with the experimental data.
NASA Technical Reports Server (NTRS)
Berrier, Bobby L.; Carter, Melissa B.; Allan, Brian G.
2005-01-01
An experimental investigation of a flush-mounted, S-duct inlet with large amounts of boundary layer ingestion has been conducted at Reynolds numbers up to full scale. The study was conducted in the NASA Langley Research Center 0.3-Meter Transonic Cryogenic Tunnel. In addition, a supplemental computational study on one of the inlet configurations was conducted using the Navier-Stokes flow solver, OVERFLOW. Tests were conducted at Mach numbers from 0.25 to 0.83, Reynolds numbers (based on aerodynamic interface plane diameter) from 5.1 million to 13.9 million (full-scale value), and inlet mass-flow ratios from 0.29 to 1.22, depending on Mach number. Results of the study indicated that increasing Mach number, increasing boundary layer thickness (relative to inlet height) or ingesting a boundary layer with a distorted profile decreased inlet performance. At Mach numbers above 0.4, increasing inlet airflow increased inlet pressure recovery but also increased distortion. Finally, inlet distortion was found to be relatively insensitive to Reynolds number, but pressure recovery increased slightly with increasing Reynolds number.This CD-ROM supplement contains inlet data including: Boundary layer data, Duct static pressure data, performance-AIP (fan face) data, Photos, Tunnel wall P-PTO data and definitions.
NASA Technical Reports Server (NTRS)
Berrier, Bobby L.; Carter, Melissa B.; Allan, Brian G.
2005-01-01
An experimental investigation of a flush-mounted, S-duct inlet with large amounts of boundary layer ingestion has been conducted at Reynolds numbers up to full scale. The study was conducted in the NASA Langley Research Center 0.3-Meter Transonic Cryogenic Tunnel. In addition, a supplemental computational study on one of the inlet configurations was conducted using the Navier-Stokes flow solver, OVERFLOW. Tests were conducted at Mach numbers from 0.25 to 0.83, Reynolds numbers (based on aerodynamic interface plane diameter) from 5.1 million to 13.9 million (full-scale value), and inlet mass-flow ratios from 0.29 to 1.22, depending on Mach number. Results of the study indicated that increasing Mach number, increasing boundary layer thickness (relative to inlet height) or ingesting a boundary layer with a distorted profile decreased inlet performance. At Mach numbers above 0.4, increasing inlet airflow increased inlet pressure recovery but also increased distortion. Finally, inlet distortion was found to be relatively insensitive to Reynolds number, but pressure recovery increased slightly with increasing Reynolds number.
Activation process in excitable systems with multiple noise sources: Large number of units.
Franović, Igor; Perc, Matjaž; Todorović, Kristina; Kostić, Srdjan; Burić, Nikola
2015-12-01
We study the activation process in large assemblies of type II excitable units whose dynamics is influenced by two independent noise terms. The mean-field approach is applied to explicitly demonstrate that the assembly of excitable units can itself exhibit macroscopic excitable behavior. In order to facilitate the comparison between the excitable dynamics of a single unit and an assembly, we introduce three distinct formulations of the assembly activation event. Each formulation treats different aspects of the relevant phenomena, including the thresholdlike behavior and the role of coherence of individual spikes. Statistical properties of the assembly activation process, such as the mean time-to-first pulse and the associated coefficient of variation, are found to be qualitatively analogous for all three formulations, as well as to resemble the results for a single unit. These analogies are shown to derive from the fact that global variables undergo a stochastic bifurcation from the stochastically stable fixed point to continuous oscillations. Local activation processes are analyzed in the light of the competition between the noise-led and the relaxation-driven dynamics. We also briefly report on a system-size antiresonant effect displayed by the mean time-to-first pulse. PMID:26764779
Hard Numbers for Large Molecules: Toward Exact Energetics for Supramolecular Systems.
Ambrosetti, Alberto; Alfè, Dario; DiStasio, Robert A; Tkatchenko, Alexandre
2014-03-01
Noncovalent interactions are ubiquitous in molecular and condensed-phase environments, and hence a reliable theoretical description of these fundamental interactions could pave the way toward a more complete understanding of the microscopic underpinnings for a diverse set of systems in chemistry and biology. In this work, we demonstrate that recent algorithmic advances coupled to the availability of large-scale computational resources make the stochastic quantum Monte Carlo approach to solving the Schrödinger equation an optimal contender for attaining "chemical accuracy" (1 kcal/mol) in the binding energies of supramolecular complexes of chemical relevance. To illustrate this point, we considered a select set of seven host-guest complexes, representing the spectrum of noncovalent interactions, including dispersion or van der Waals forces, π-π stacking, hydrogen bonding, hydrophobic interactions, and electrostatic (ion-dipole) attraction. A detailed analysis of the interaction energies reveals that a complete theoretical description necessitates treatment of terms well beyond the standard London and Axilrod-Teller contributions to the van der Waals dispersion energy. PMID:26274077
Activation process in excitable systems with multiple noise sources: Large number of units
NASA Astrophysics Data System (ADS)
Franović, Igor; Perc, Matjaž; Todorović, Kristina; Kostić, Srdjan; Burić, Nikola
2015-12-01
We study the activation process in large assemblies of type II excitable units whose dynamics is influenced by two independent noise terms. The mean-field approach is applied to explicitly demonstrate that the assembly of excitable units can itself exhibit macroscopic excitable behavior. In order to facilitate the comparison between the excitable dynamics of a single unit and an assembly, we introduce three distinct formulations of the assembly activation event. Each formulation treats different aspects of the relevant phenomena, including the thresholdlike behavior and the role of coherence of individual spikes. Statistical properties of the assembly activation process, such as the mean time-to-first pulse and the associated coefficient of variation, are found to be qualitatively analogous for all three formulations, as well as to resemble the results for a single unit. These analogies are shown to derive from the fact that global variables undergo a stochastic bifurcation from the stochastically stable fixed point to continuous oscillations. Local activation processes are analyzed in the light of the competition between the noise-led and the relaxation-driven dynamics. We also briefly report on a system-size antiresonant effect displayed by the mean time-to-first pulse.
Tectonic stress field of China inferred from a large number of small earthquakes
NASA Astrophysics Data System (ADS)
1992-07-01
Mean principal tress axes were inferred for China using 9621 P wave first motion polarity readings from 5054 small earthquakes (1<=ML<=5). The area studied was divided into 76 subregions. The mean P (compressive), B (intermediate), and T (relatively tensional) axes corresponding to composite focal mechanism solutions of multiple earthquakes for each subregion were determined by a grid test to all possible orientations of the P, B, and T axes with a step of 5° or 10°. In order to get a relatively homogeneous sampling in space we have avoided using the readings from spatially and temporally clustered earthquakes. We have rechecked most of the polarity readings by inspection of original seismograms. The focal mechanism solutions of large (M>=6) individual earthquakes are also presented for comparison. The results indicate the existence of an overall radial pattern of the present-day maximum horizontal stress orientations throughout the continental area of China. This pattern is thought to be closely related to indentor models of continental collision between the Indian Ocean and the Eurasian plate.
NASA Astrophysics Data System (ADS)
Corsini, Alessandro; Mulas, Marco; Marcato, Gianluca; Chinellato, Giulia; Mair, Volkmar
2015-04-01
In the Dolomites of Italy, snowfall during winter 2013/2014 was exceptionally abundant. Major snowfall events occurred from late December 2013 to mid-March 2014. Snow accumulation in Badia Valley peaked in early February: from 2 to 4 meters with a positive gradient respect to altimetry and accordingly to wind accumulation zones. Below 2000 m asl, due to the mild temperatures recorded before the onset of snowfall, the relatively dry snow cover was mostly deposited on top of unfrozen soils. The Corvara landslide is a large active earthflow located close to Corvara in Badia, at an elevation from 2000 to 1600 m. It's displacement rate before, during and after the exceptional snowfall period was monitored at high temporal frequency. Surface displacement was measured bi-weekly by differential GPS in several benchmarks in the source, track and accumulation zone. Deep displacement was monitored semi-continuously by two in-place inclinometers at 48 m depth in the accumulation zone, across the main deep-seated sliding surface. Results show an acceleration of movements, both at surface and at depth, soon after the massive snow accumulation event of 31st January to 2nd February 2014, which suddenly increased snow thickness from 1 to more than 2 metres. Short time lags between the onset of the acceleration of movements in the source, the track and the accumulation zones were also recorded. The landslide then maintained a relatively constant velocity during the high snow cover period extended to earlyApril and underwent a progressive deceleration during the snowmelt period that lasted until mid-June. The fact that the acceleration of the Corvara earthflow was triggered by a massive and rapid snow accumulation event, provides a quite different perspective from the generally adopted one that considers the destabilizing effect of snow only in relation to the increase of groundwater level during rapid snowmelt. A full explanation of the processes associated to the dynamics observed
Three-dimensional structure of confined swirling jets at moderately large Reynolds numbers
NASA Astrophysics Data System (ADS)
Sanmiguel-Rojas, E.; Burgos, M. A.; del Pino, C.; Fernandez-Feria, R.
2008-04-01
We have performed a series of three-dimensional (3D) numerical simulations of the incompressible flow discharging from a rotating pipe into a coaxial static cylindrical container through a sudden expansion. We have considered several values of the Reynolds number based on the pipe flow rate ReQ between 50 and 300, and an expansion diameter ratio of 8, and have analyzed the emerging 3D flow structures in the swirling jet exiting from the rotating pipe as the swirl parameter S is increased. The results are compared to axisymmetric numerical simulations of the same problem. Three-dimensional, nonlinear instabilities are found in the swirling jet when ReQ≳98 above a critical value of S, which depends on ReQ, that obviously do not appear in the axisymmetric simulations. These nonlinear instabilities are initially triggered by the linear instabilities inside the rotating pipe, which are already present in the pipe from a much lower value of S, and are transformed in the jet. As S increases further, there exists another critical value above which the swirling jet undergoes vortex breakdown, producing a flow in the jet which is basically axisymmetric. This critical value of the swirl parameter for breakdown is significantly larger than that found in the axisymmetric simulations. Thus, one of the main results of the present work is that 3D instabilities delay the formation of vortex breakdown in the jet, in relation to the same axisymmetric flow, but once the vortex breakdown phenomenon occurs, the 3D instabilities coming from the rotating pipe appear to be suppressed in the jet, and the swirling flow becomes basically axisymmetric again. Finally, the axisymmetric simulations show that the jet becomes unstable to axisymmetric perturbations, when ReQ≳188, above another critical value of S. However, these axisymmetric instabilities do not appear in the 3D simulations because the flow becomes unstable to asymmetric perturbations at much lower values of S.
Ren, Junjie; Zhang, Shimin
2013-01-01
Recurrence interval of large earthquake on an active fault zone is an important parameter in assessing seismic hazard. The 2008 Wenchuan earthquake (Mw 7.9) occurred on the central Longmen Shan fault zone and ruptured the Yingxiu-Beichuan fault (YBF) and the Guanxian-Jiangyou fault (GJF). However, there is a considerable discrepancy among recurrence intervals of large earthquake in preseismic and postseismic estimates based on slip rate and paleoseismologic results. Post-seismic trenches showed that the central Longmen Shan fault zone probably undertakes an event similar to the 2008 quake, suggesting a characteristic earthquake model. In this paper, we use the published seismogenic model of the 2008 earthquake based on Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data and construct a characteristic seismic moment accumulation/release model to estimate recurrence interval of large earthquakes on the central Longmen Shan fault zone. Our results show that the seismogenic zone accommodates a moment rate of (2.7 ± 0.3) × 10¹⁷ N m/yr, and a recurrence interval of 3900 ± 400 yrs is necessary for accumulation of strain energy equivalent to the 2008 earthquake. This study provides a preferred interval estimation of large earthquakes for seismic hazard analysis in the Longmen Shan region. PMID:23878524
Zhang, Shimin
2013-01-01
Recurrence interval of large earthquake on an active fault zone is an important parameter in assessing seismic hazard. The 2008 Wenchuan earthquake (Mw 7.9) occurred on the central Longmen Shan fault zone and ruptured the Yingxiu-Beichuan fault (YBF) and the Guanxian-Jiangyou fault (GJF). However, there is a considerable discrepancy among recurrence intervals of large earthquake in preseismic and postseismic estimates based on slip rate and paleoseismologic results. Post-seismic trenches showed that the central Longmen Shan fault zone probably undertakes an event similar to the 2008 quake, suggesting a characteristic earthquake model. In this paper, we use the published seismogenic model of the 2008 earthquake based on Global Positioning System (GPS) and Interferometric Synthetic Aperture Radar (InSAR) data and construct a characteristic seismic moment accumulation/release model to estimate recurrence interval of large earthquakes on the central Longmen Shan fault zone. Our results show that the seismogenic zone accommodates a moment rate of (2.7 ± 0.3) × 1017 N m/yr, and a recurrence interval of 3900 ± 400 yrs is necessary for accumulation of strain energy equivalent to the 2008 earthquake. This study provides a preferred interval estimation of large earthquakes for seismic hazard analysis in the Longmen Shan region. PMID:23878524
Gilbert, Jack A.; Field, Dawn; Huang, Ying; Edwards, Rob; Li, Weizhong; Gilna, Paul; Joint, Ian
2008-01-01
Background Sequencing the expressed genetic information of an ecosystem (metatranscriptome) can provide information about the response of organisms to varying environmental conditions. Until recently, metatranscriptomics has been limited to microarray technology and random cloning methodologies. The application of high-throughput sequencing technology is now enabling access to both known and previously unknown transcripts in natural communities. Methodology/Principal Findings We present a study of a complex marine metatranscriptome obtained from random whole-community mRNA using the GS-FLX Pyrosequencing technology. Eight samples, four DNA and four mRNA, were processed from two time points in a controlled coastal ocean mesocosm study (Bergen, Norway) involving an induced phytoplankton bloom producing a total of 323,161,989 base pairs. Our study confirms the finding of the first published metatranscriptomic studies of marine and soil environments that metatranscriptomics targets highly expressed sequences which are frequently novel. Our alternative methodology increases the range of experimental options available for conducting such studies and is characterized by an exceptional enrichment of mRNA (99.92%) versus ribosomal RNA. Analysis of corresponding metagenomes confirms much higher levels of assembly in the metatranscriptomic samples and a far higher yield of large gene families with >100 members, ∼91% of which were novel. Conclusions/Significance This study provides further evidence that metatranscriptomic studies of natural microbial communities are not only feasible, but when paired with metagenomic data sets, offer an unprecedented opportunity to explore both structure and function of microbial communities – if we can overcome the challenges of elucidating the functions of so many never-seen-before gene families. PMID:18725995
What caused a large number of fatalities in the Tohoku earthquake?
NASA Astrophysics Data System (ADS)
Ando, M.; Ishida, M.; Nishikawa, Y.; Mizuki, C.; Hayashi, Y.
2012-04-01
The Mw9.0 earthquake caused 20,000 deaths and missing persons in northeastern Japan. 115 years prior to this event, there were three historical tsunamis that struck the region, one of which is a "tsunami earthquake" resulted with a death toll of 22,000. Since then, numerous breakwaters were constructed along the entire northeastern coasts and tsunami evacuation drills were carried out and hazard maps were distributed to local residents on numerous communities. However, despite the constructions and preparedness efforts, the March 11 Tohoku earthquake caused numerous fatalities. The strong shaking lasted three minutes or longer, thus all residents recognized that this is the strongest and longest earthquake that they had been ever experienced in their lives. The tsunami inundated an enormous area at about 560km2 over 35 cities along the coast of northeast Japan. To find out the reasons behind the high number of fatalities due to the March 11 tsunami, we interviewed 150 tsunami survivors at public evacuation shelters in 7 cities mainly in Iwate prefecture in mid-April and early June 2011. Interviews were done for about 30min or longer focused on their evacuation behaviors and those that they had observed. On the basis of the interviews, we found that residents' decisions not to evacuate immediately were partly due to or influenced by earthquake science results. Below are some of the factors that affected residents' decisions. 1. Earthquake hazard assessments turned out to be incorrect. Expected earthquake magnitudes and resultant hazards in northeastern Japan assessed and publicized by the government were significantly smaller than the actual Tohoku earthquake. 2. Many residents did not receive accurate tsunami warnings. The first tsunami warning were too small compared with the actual tsunami heights. 3. The previous frequent warnings with overestimated tsunami height influenced the behavior of the residents. 4. Many local residents above 55 years old experienced
Rodriguez, Crystal M; de Jongh, Arent; Meuwly, Didier
2012-03-01
Statistical research on fingerprint identification and the testing of automated fingerprint identification system (AFIS) performances require large numbers of forensic fingermarks. These fingermarks are rarely available. This study presents a semi-automatic method to create simulated fingermarks in large quantities that model minutiae features or images of forensic fingermarks. This method takes into account several aspects contributing to the variability of forensic fingermarks such as the number of minutiae, the finger region, and the elastic deformation of the skin. To investigate the applicability of the simulated fingermarks, fingermarks have been simulated with 5-12 minutiae originating from different finger regions for six fingers. An AFIS matching algorithm was used to obtain similarity scores for comparisons between the minutiae configurations of fingerprints and the minutiae configurations of simulated and forensic fingermarks. The results showed similar scores for both types of fingermarks suggesting that the simulated fingermarks are good substitutes for forensic fingermarks. PMID:22103733
NASA Astrophysics Data System (ADS)
Zheng, M.; Wu, X.
2015-12-01
The basis geological problem is still the bottleneck of the exploration work of the lager Sanjiang basin groups. In general terms, the problems are including the prototype basins and basin forming mechanism of two aspects. In this paper, using the field geological survey and investigation, logging data analysis, seismic data interpretation technical means large Sanjiang basin groups and basin forming mechanism of the prototype are discussed. Main draw the following conclusions： 1. Sanjiang region group-level formation can be completely contrasted. 2. Tension faults, compressive faults, shear structure composition and structure combination of four kinds of compound fracture are mainly developed In the study area. The direction of their distribution can be divided into SN, EW, NNE, NEE, NNW, NWW to other groups of fracture. 3. Large Sanjiang basin has the SN and the EW two main directions of tectonic evolution. Cenozoic basins in Sanjiang region in group formation located the two tectonic domains of ancient Paleo-Asian Ocean and the Pacific Interchange. 4. Large Sanjiang basin has experienced in the late Mesozoic tectonic evolution of two-stage and nine times. The first stage, developmental stage basement, they are ① Since the Mesozoic era and before the Jurassic; ② Early Jurassic period; The second stage, cap stage of development, they are ③ Late Jurassic depression developmental stages of compression; ④ Early Cretaceous rifting stage; ⑤ depression in mid-Early Cretaceous period; ⑥ tensile Early Cretaceous rifting stage; ⑦ inversion of Late Cretaceous tectonic compression stage; ⑧ Paleogene - Neogene; ⑨ After recently Ji Baoquan Sedimentary Ridge. 5. Large Sanjiang basin group is actually a residual basin structure, and Can be divided into left - superimposed (Founder, Tangyuan depression, Hulin Basin), residual - inherited type (Sanjiang basin), residual - reformed (Jixi, Boli, Hegang basin). there are two developed depression and the mechanism
NASA Astrophysics Data System (ADS)
Wang, BoBin; Wang, ZhiShi; Cui, GuiXiang; Zhang, ZhaoShun
2014-06-01
In this paper, the dynamic characteristics of building clusters are simulated by large eddy simulation at high Reynolds number for both homogeneous and heterogeneous building clusters. To save the computational cost a channel-like flow model is applied to the urban canopy with free slip condition at the upper boundary. The results show that the domain height is an important parameter for correct evaluation of the dynamic characteristics. The domain height must be greater than 8 h ( h is the average building height) in order to obtain correct roughness height while displacement height and roughness sublayer are less sensitive to the domain height. The Reynolds number effects on the dynamic characteristics and flow patterns are investigated. The turbulence intensity is stronger inside building cluster at high Reynolds number while turbulence intensity is almost unchanged with Reynolds number above the building cluster. Roughness height increases monotonously with Reynolds number by 20% from Re*=103 to Re*=105 but displacement height is almost unchanged. Within the canopy layer of heterogeneous building clusters, flow structures vary between buildings and turbulence is more active at high Reynolds number.
Brahmachary, Manisha; Guilmatre, Audrey; Quilez, Javier; Hasson, Dan; Borel, Christelle; Warburton, Peter; Sharp, Andrew J
2014-06-01
Tandem repeats are common in eukaryotic genomes, but due to difficulties in assaying them remain poorly studied. Here, we demonstrate the utility of Nanostring technology as a targeted approach to perform accurate measurement of tandem repeats even at extremely high copy number, and apply this technology to genotype 165 HapMap samples from three different populations and five species of non-human primates. We observed extreme variability in copy number of tandemly repeated genes, with many loci showing 5-10 fold variation in copy number among humans. Many of these loci show hallmarks of genome assembly errors, and the true copy number of many large tandem repeats is significantly under-represented even in the high quality 'finished' human reference assembly. Importantly, we demonstrate that most large tandem repeat variations are not tagged by nearby SNPs, and are therefore essentially invisible to SNP-based GWAS approaches. Using association analysis we identify many cis correlations of large tandem repeat variants with nearby gene expression and DNA methylation levels, indicating that variations of tandem repeat length are associated with functional effects on the local genomic environment. This includes an example where expansion of a macrosatellite repeat is associated with increased DNA methylation and suppression of nearby gene expression, suggesting a mechanism termed "repeat induced gene silencing", which has previously been observed only in transgenic organisms. We also observed multiple signatures consistent with altered selective pressures at tandemly repeated loci, suggesting important biological functions. Our studies show that tandemly repeated loci represent a highly variable fraction of the genome that have been systematically ignored by most previous studies, copy number variation of which can exert functionally significant effects. We suggest that future studies of tandem repeat loci will lead to many novel insights into their role in modulating
NASA Technical Reports Server (NTRS)
Kolesar, C. E.
1987-01-01
Research activity on an airfoil designed for a large airplane capable of very long endurance times at a low Mach number of 0.22 is examined. Airplane mission objectives and design optimization resulted in requirements for a very high design lift coefficient and a large amount of laminar flow at high Reynolds number to increase the lift/drag ratio and reduce the loiter lift coefficient. Natural laminar flow was selected instead of distributed mechanical suction for the measurement technique. A design lift coefficient of 1.5 was identified as the highest which could be achieved with a large extent of laminar flow. A single element airfoil was designed using an inverse boundary layer solution and inverse airfoil design computer codes to create an airfoil section that would achieve performance goals. The design process and results, including airfoil shape, pressure distributions, and aerodynamic characteristics are presented. A two dimensional wind tunnel model was constructed and tested in a NASA Low Turbulence Pressure Tunnel which enabled testing at full scale design Reynolds number. A comparison is made between theoretical and measured results to establish accuracy and quality of the airfoil design technique.
NASA Astrophysics Data System (ADS)
Schnitzer, Ory; Frankel, Itzchak; Yariv, Ehud
2013-11-01
In Taylor's theory of electrohydrodynamic drop deformation (Proc. R. Soc. Lond. A, vol. 291, 1966, pp. 159-166), inertia is neglected at the outset, resulting in fluid velocity that scales as the square of the applied-field magnitude. For large drops, with increasing field strength the Reynolds number predicted by this scaling may actually become large, suggesting the need for a complementary large-Reynolds-number investigation. Balancing viscous stresses and electrical shear forces in this limit reveals a different velocity scaling, with the 4/3-power of the applied-field magnitude. We focus here on the flow over a gas bubble. It is essentially confined to two boundary layers propagating from the poles to the equator, where they collide to form a radial jet. At leading order in the Capillary number, the bubble deforms due to (i) Maxwell stresses; (ii) the hydrodynamic boundary-layer pressure associated with centripetal acceleration; and (iii) the intense pressure distribution acting over the narrow equatorial deflection zone, appearing as a concentrated load. Remarkably, the unique flow topology and associated scalings allow to obtain a closed-form expression for this deformation through application of integral mass and momentum balances. On the bubble scale, the concentrated pressure load is manifested in the appearance of a non-smooth equatorial dimple.
Shibata, Hiroko; Saito, Haruna; Yomota, Chikako; Kawanishi, Toru
2009-08-13
There are two generics of a parenteral lipid emulsion of prostaglandin E1 (PGE(1)) (Lipo-PGE(1)) in addition to two innovators. It was reported the change from innovator to generic in clinical practice caused the slowing of drip rate and formation of aggregates in the infusion line. Thus, we investigated the difference of pharmaceutical quality in these Lipo-PGE(1) formulations. After mixing with some infusion solutions, the mean diameter and number of large particles were determined. Although the mean diameter did not change in any infusion solutions, the number of large particles (diameter >1.0 microm) dramatically increased in generics with Hartmann's solution pH 8 or Lactec injection with 7% sodium bicarbonate. Next, we investigated the effect of these infusion solutions on the retention rate of PGE(1) in lipid particles. The retention rate of PGE(1) in these two infusion solutions decreased more quickly than that in normal saline. Nevertheless, there were no significant differences among the formulations tested. Our results suggest that there is no difference between innovators and generics except in mixing with these infusion solutions. Furthermore, that monitoring the number of large particles can be an effective means of evaluating pharmaceutical interactions and/or the stability of lipid emulsions. PMID:19465103
Beran, Michael J; Parrish, Audrey E
2016-08-01
A key issue in understanding the evolutionary and developmental emergence of numerical cognition is to learn what mechanism(s) support perception and representation of quantitative information. Two such systems have been proposed, one for dealing with approximate representation of sets of items across an extended numerical range and another for highly precise representation of only small numbers of items. Evidence for the first system is abundant across species and in many tests with human adults and children, whereas the second system is primarily evident in research with children and in some tests with non-human animals. A recent paper (Choo & Franconeri, Psychonomic Bulletin & Review, 21, 93-99, 2014) with adult humans also reported "superprecise" representation of small sets of items in comparison to large sets of items, which would provide more support for the presence of a second system in human adults. We first presented capuchin monkeys with a test similar to that of Choo and Franconeri in which small or large sets with the same ratios had to be discriminated. We then presented the same monkeys with an expanded range of comparisons in the small number range (all comparisons of 1-9 items) and the large number range (all comparisons of 10-90 items in 10-item increments). Capuchin monkeys showed no increased precision for small over large sets in making these discriminations in either experiment. These data indicate a difference in the performance of monkeys to that of adult humans, and specifically that monkeys do not show improved discrimination performance for small sets relative to large sets when the relative numerical differences are held constant. PMID:26689808
Zhou, Ye; Thornber, Ben
2016-04-12
Here, the implicit large-eddy simulation (ILES) has been utilized as an effective approach for calculating many complex flows at high Reynolds number flows. Richtmyer–Meshkov instability (RMI) induced flow can be viewed as a homogeneous decaying turbulence (HDT) after the passage of the shock. In this article, a critical evaluation of three methods for estimating the effective Reynolds number and the effective kinematic viscosity is undertaken utilizing high-resolution ILES data. Effective Reynolds numbers based on the vorticity and dissipation rate, or the integral and inner-viscous length scales, are found to be the most self-consistent when compared to the expected phenomenology andmore » wind tunnel experiments.« less
NASA Astrophysics Data System (ADS)
Kuriyam, Masafumi; Li, Xiangyi; Harada, Eiji; Konno, Hirotaka
An investigation was performed on the flow and cooling characteristics of highly viscous liquids in the channel with a large number of right-angled bends. The variation of flow pattern and temperature profile according to Reynolds number and Prandtl number were presented by solving numerically the Navier-Stokes equations with energy equation under the condition that the fluid properties were independent on temperature. Average heat transfer cofficient and friction factor were also calculated and compared with the experimental data regarding aqueous solutions of corn syrup. Through the comparison, the effect of the variable viscosity of the test fluid on the flow and heat transfer characteristics was considered in connection with the channel configuration.
NASA Astrophysics Data System (ADS)
Bishop, R. F.; Li, P. H. Y.
2016-06-01
The coupled cluster method (CCM) is employed to very high orders of approximation to study the ground-state (GS) properties of the spin-s Heisenberg antiferromagnet (with isotropic interactions, all of equal strength, between nearest-neighbour pairs only) on the honeycomb lattice. We calculate with high accuracy the complete set of GS parameters that fully describes the low-energy behaviour of the system, in terms of an effective magnon field theory, viz., the energy per spin, the magnetic order parameter (i.e., the sublattice magnetization), the spin stiffness and the zero-field (uniform, transverse) magnetic susceptibility, for all values of the spin quantum numbers in the range 1/2 ≤ s ≤ 9/2. The CCM data points are used to calculate the leading quantum corrections to the classical (s → ∞) values of these low-energy parameters, considered as large-s asymptotic expansions.
Wannaz, E D; Rodriguez, J H; Wolfsberger, T; Carreras, H A; Pignata, M L; Fangmeier, A; Franzaring, J
2012-01-01
A pollution gradient was observed in tree foliage sampled in the vicinity of a large aluminium production facility in Patagonia (Argentina). Leaves of Eucalyptus rostrata, and Populus hybridus and different needle ages of Pinus spec. were collected and concentrations of aluminium (Al) and sulphur (S) as well as physiological parameters (chlorophyll and lipid oxidation products) were analyzed. Al and S concentrations indicate a steep pollution gradient in the study showing a relationship with the physiological parameters in particular membrane lipid oxidation products. The present study confirms that aluminium smelting results in high Al and sulphur deposition in the study area, and therefore further studies should be carried out taking into account potentially adverse effects of these compounds on human and ecosystem health. PMID:22654642
Wannaz, E. D.; Rodriguez, J. H.; Wolfsberger, T.; Carreras, H. A.; Pignata, M. L.; Fangmeier, A.; Franzaring, J.
2012-01-01
A pollution gradient was observed in tree foliage sampled in the vicinity of a large aluminium production facility in Patagonia (Argentina). Leaves of Eucalyptus rostrata, and Populus hybridus and different needle ages of Pinus spec. were collected and concentrations of aluminium (Al) and sulphur (S) as well as physiological parameters (chlorophyll and lipid oxidation products) were analyzed. Al and S concentrations indicate a steep pollution gradient in the study showing a relationship with the physiological parameters in particular membrane lipid oxidation products. The present study confirms that aluminium smelting results in high Al and sulphur deposition in the study area, and therefore further studies should be carried out taking into account potentially adverse effects of these compounds on human and ecosystem health. PMID:22654642
Kitterer, Daniel; Braun, Niko; Alscher, M Dominik; Segerer, Stephan; Latus, Joerg
2016-01-01
Background Encapsulating peritoneal sclerosis (EPS) is the most severe complication associated with long-term peritoneal dialysis (PD). Previous studies noticed a sharp decline in new patients with severe EPS. We investigated the number of severe EPS patients in our large referral center over almost 20 years. Methods All late-stage EPS patients who underwent major surgery due to extensive symptoms caused by bowel obstruction (vomiting, abdominal pain, and weight loss) between March 1997 and end of December 2015 in our hospital were included in the present study. An index was calculated between the number of patients with severe EPS and the implanted PD catheters in our center. Results Between 1979 and 2015, a total of 745 PD catheters were implanted in our center, with a steady increase in the numbers between 2003 and 2015. First patient with severe EPS was treated in 1998, then a rise in the number of patients with EPS was present in 2005. The number of patients with EPS peaked in the period of 2010–2012 (15 patients within 3 years). Afterward, both the absolute numbers and the index between the number of patients with severe EPS and the implanted catheters demonstrated a prominent reduction in the next 3-year period from 2013 to 2015. Conclusion Our data support the hypothesis that there seems to be a decrease of late-stage EPS incidence over the last years, but data about milder or asymptomatic patients are lacking. This should be kept in mind while giving the patients information about different renal replacement therapies at start of dialysis. PMID:27540308
Type I error robustness of ANOVA and ANOVA on ranks when the number of treatments is large.
Brownie, C; Boos, D D
1994-06-01
Agricultural screening trials often involve a large number (t) of treatments in a complete block design with limited replication (b = 3 or 4 blocks). The null hypothesis of interest is that of no differences between treatments. For the commonly used analysis of variance (ANOVA) procedure, most texts do not discuss agreement between actual and nominal Type I error rates in the presence of nonnormality, in this small b, large t, situation. Similarly, for the Friedman and the increasingly popular "ANOVA on ranks" procedures, it is not easy to find results concerning null performance given b small and t large. In this article, we therefore present results, from two different bodies of theory, that provide useful insight concerning null performance of these ANOVA and rank procedures when t is large. The two types of theory are (i) the classical approach based on moment approximations to the permutation distribution, and (ii) central-limit-theory-based asymptotics in the nonstandard t--> infinity situation. Both approaches demonstrate the validity of standard ANOVA and of ANOVA on within-block ranks, under nonnormality when t is large. Choice of the procedure to be used on a given data set should therefore be based on consideration of power properties. In general, ANOVA on ranks will be superior to standard ANOVA for data with frequent extreme values. PMID:19405210
Tahara, Y.; Stern, F.
1996-09-01
A large-domain approach is developed for calculating ship boundary layers and wakes and wave fields for nonzero Froude number. The Reynolds-averaged Navier-Stokes and continuity equations are solved with the Baldwin-Lomax turbulence model, exact nonlinear kinematic and approximate dynamic free-surface boundary conditions, and a body/free-surface conforming grid. The results are validated through comparisons with data for the Series 60 C{sub B} = 0.6 ship model at low and high Froude numbers and results of a precursory interactive approach. Both approaches yield satisfactory results; however, the large-domain results indicate improved resolution of the flow close to the hull and wake centerplane and of the Froucle number differences due to near-wall turbulence modeling and non-linear free-surface boundary conditions. Additional evaluation is provided through discussion of the recent CFD Workshop Tokyo 1994, where both methods were among the best. Last, some concluding remarks are made. 20 refs., 7 figs.
Park, KeeHyun; Lim, SeungHyeon
2015-01-01
In this paper, a multilayer secure biomedical data management system for managing a very large number of diverse personal health devices is proposed. The system has the following characteristics: the system supports international standard communication protocols to achieve interoperability. The system is integrated in the sense that both a PHD communication system and a remote PHD management system work together as a single system. Finally, the system proposed in this paper provides user/message authentication processes to securely transmit biomedical data measured by PHDs based on the concept of a biomedical signature. Some experiments, including the stress test, have been conducted to show that the system proposed/constructed in this study performs very well even when a very large number of PHDs are used. For a stress test, up to 1,200 threads are made to represent the same number of PHD agents. The loss ratio of the ISO/IEEE 11073 messages in the normal system is as high as 14% when 1,200 PHD agents are connected. On the other hand, no message loss occurs in the multilayered system proposed in this study, which demonstrates the superiority of the multilayered system to the normal system with regard to heavy traffic. PMID:26247034
Mátyus, Edit; Simunek, Ján; Császár, Attila G
2009-08-21
In a recent publication [J. Chem. Phys. 127, 084102 (2007)], the nearly variational DEWE approach (DEWE denotes Discrete variable representation of the Watson Hamiltonian using the Eckart frame and an Exact inclusion of a potential energy surface expressed in arbitrarily chosen coordinates) was developed to compute a large number of (ro)vibrational eigenpairs for medium-sized semirigid molecules having a single well-defined minimum. In this publication, memory, CPU, and hard disk usage requirements of DEWE, and thus of any DEWE-type approach, are carefully considered, analyzed, and optimized. Particular attention is paid to the sparse matrix-vector multiplication, the most expensive part of the computation, and to rate-determining steps in the iterative Lanczos eigensolver, including spectral transformation, reorthogonalization, and restart of the iteration. Algorithmic improvements are discussed in considerable detail. Numerical results are presented for the vibrational band origins of the (12)CH(4) and (12)CH(2)D(2) isotopologues of the methane molecule. The largest matrix handled on a personal computer during these computations is of the size of (4x10(8))x(4x10(8)). The best strategy for determining vibrational eigenpairs depends largely on the actual details of the required computation. Nevertheless, for a usual scenario requiring a large number of the lowest eigenpairs of the Hamiltonian matrix the combination of the thick-restart Lanczos method, shift-fold filtering, and periodic reorthogonalization appears to result in the computationally most feasible approach. PMID:19708731
NASA Astrophysics Data System (ADS)
Skála, J.; Baruffa, F.; Büchner, J.; Rampp, M.
2015-08-01
Context. The numerical simulation of turbulence and flows in almost ideal astrophysical plasmas with large Reynolds numbers motivates the implementation of magnetohydrodynamical (MHD) computer codes with low resistivity. They need to be computationally efficient and scale well with large numbers of CPU cores, allow obtaining a high grid resolution over large simulation domains, and be easily and modularly extensible, for instance, to new initial and boundary conditions. Aims: Our aims are the implementation, optimization, and verification of a computationally efficient, highly scalable, and easily extensible low-dissipative MHD simulation code for the numerical investigation of the dynamics of astrophysical plasmas with large Reynolds numbers in three dimensions (3D). Methods: The new GOEMHD3 code discretizes the ideal part of the MHD equations using a fast and efficient leap-frog scheme that is second-order accurate in space and time and whose initial and boundary conditions can easily be modified. For the investigation of diffusive and dissipative processes the corresponding terms are discretized by a DuFort-Frankel scheme. To always fulfill the Courant-Friedrichs-Lewy stability criterion, the time step of the code is adapted dynamically. Numerically induced local oscillations are suppressed by explicit, externally controlled diffusion terms. Non-equidistant grids are implemented, which enhance the spatial resolution, where needed. GOEMHD3 is parallelized based on the hybrid MPI-OpenMP programing paradigm, adopting a standard two-dimensional domain-decomposition approach. Results: The ideal part of the equation solver is verified by performing numerical tests of the evolution of the well-understood Kelvin-Helmholtz instability and of Orszag-Tang vortices. The accuracy of solving the (resistive) induction equation is tested by simulating the decay of a cylindrical current column. Furthermore, we show that the computational performance of the code scales very
Walker, A.D.M. )
1987-09-01
A new hydromagnetic theory is developed for describing compressional pulsations with azimuthal wave number. It is assumed that there are two plasma, one hot, in which pressure effects are important, and the other cold. The equations are derived in a general set of magnetic coordinates which allow realistic calculations including geometrical effects in the magnetosphere. The equations describe the three hydromagnetic modes which are coupled by the geometry. When the azimuthal wave number is large, the fast mode is strongly evanescent. This allows an expansion in 1/m in order to decouple the fast wave. The remaining equations describe the coupled transverse Alfven and magnetosonic modes. Some of the puzzling features of the observations of polarization are discussed.
Sebastián, Elena; Alcoceba, Miguel; Martín-García, David; Blanco, Óscar; Sanchez-Barba, Mercedes; Balanzategui, Ana; Marín, Luis; Montes-Moreno, Santiago; González-Barca, Eva; Pardal, Emilia; Jiménez, Cristina; García-Álvarez, María; Clot, Guillem; Carracedo, Ángel; Gutiérrez, Norma C; Sarasquete, M Eugenia; Chillón, Carmen; Corral, Rocío; Prieto-Conde, M Isabel; Caballero, M Dolores; Salaverria, Itziar; García-Sanz, Ramón; González, Marcos
2016-01-01
Copy number analysis can be useful for assessing prognosis in diffuse large B cell lymphoma (DLBCL). We analyzed copy number data from tumor samples of 60 patients diagnosed with DLBCL de novo and their matched normal samples. We detected 63 recurrent copy number alterations (CNAs), including 33 gains, 30 losses, and nine recurrent acquired copy number neutral loss of heterozygosity (CNN-LOH). Interestingly, 20 % of cases acquired CNN-LOH of 6p21 locus, which involves the HLA region. In normal cells, there were no CNAs but we observed CNN-LOH involving some key lymphoma regions such as 6p21 and 9p24.1 (5 %) and 17p13.1 (2.5 %) in DLBCL patients. Furthermore, a model with some specific CNA was able to predict the subtype of DLBCL, 1p36.32 and 10q23.31 losses being restricted to germinal center B cell-like (GCB) DLBCL. In contrast, 8p23.3 losses and 11q24.3 gains were strongly associated with the non-GCB subtype. A poor prognosis was associated with biallelic inactivation of TP53 or 18p11.32 losses, while prognosis was better in cases carrying 11q24.3 gains. In summary, CNA abnormalities identify specific DLBCL groups, and we describe CNN-LOH in germline cells from DLBCL patients that are associated with genes that probably play a key role in DLBCL development. PMID:26573278
NASA Technical Reports Server (NTRS)
Nebenfuhr, A.; Lomax, T. L.
1998-01-01
We have developed an improved method for determination of gene expression levels with RT-PCR. The procedure is rapid and does not require extensive optimization or densitometric analysis. Since the detection of individual transcripts is PCR-based, small amounts of tissue samples are sufficient for the analysis of expression patterns in large gene families. Using this method, we were able to rapidly screen nine members of the Aux/IAA family of auxin-responsive genes and identify those genes which vary in message abundance in a tissue- and light-specific manner. While not offering the accuracy of conventional semi-quantitative or competitive RT-PCR, our method allows quick screening of large numbers of genes in a wide range of RNA samples with just a thermal cycler and standard gel analysis equipment.
Ng, K C; Heredia, K H; Kliewer, D
2012-03-01
A laser induced fluorescence system, in combination with a glass-frit nebulizer and a photo-voltaic cell detector, is described for single molecule detection. The glass-frit nebulizer continuously generates a large number of droplets with an average droplet size of three micrometers in diameter. Rhodamine 6G molecules were detected at the 10(-12) M level. Concentrations 10(-12)-10(-10) M would provide mostly single molecules (0, 1, 2, 3, ...) in the individual droplets, as determined by Poisson distribution. PMID:22462973
NASA Astrophysics Data System (ADS)
Ng, K. C.; Heredia, K. H.; Kliewer, D.
2012-03-01
A laser induced fluorescence system, in combination with a glass-frit nebulizer and a photo-voltaic cell detector, is described for single molecule detection. The glass-frit nebulizer continuously generates a large number of droplets with an average droplet size of three micrometers in diameter. Rhodamine 6G molecules were detected at the 10-12 M level. Concentrations 10-12-10-10 M would provide mostly single molecules (0, 1, 2, 3, …) in the individual droplets, as determined by Poisson distribution.
DOE R&D Accomplishments Database
Cronin, J. W.; Frisch, H. J.; Shochet, M. J.; Boymond, J. P.; Mermod, R.; Piroue, P. A.; Sumner, R. L.
1974-07-15
In an experiment at the Fermi National Accelerator Laboratory we have compared the production of large transverse momentum hadrons from targets of W, Ti, and Be bombarded by 300 GeV protons. The hadron yields were measured at 90 degrees in the proton-nucleon c.m. system with a magnetic spectrometer equipped with 2 Cerenkov counters and a hadron calorimeter. The production cross-sections have a dependence on the atomic number A that grows with P{sub 1}, eventually leveling off proportional to A{sup 1.1}.
Accumulate-Repeat-Accumulate-Accumulate-Codes
NASA Technical Reports Server (NTRS)
Divsalar, Dariush; Dolinar, Sam; Thorpe, Jeremy
2004-01-01
Inspired by recently proposed Accumulate-Repeat-Accumulate (ARA) codes [15], in this paper we propose a channel coding scheme called Accumulate-Repeat-Accumulate-Accumulate (ARAA) codes. These codes can be seen as serial turbo-like codes or as a subclass of Low Density Parity Check (LDPC) codes, and they have a projected graph or protograph representation; this allows for a high-speed iterative decoder implementation using belief propagation. An ARAA code can be viewed as a precoded Repeat-and-Accumulate (RA) code with puncturing in concatenation with another accumulator, where simply an accumulator is chosen as the precoder; thus ARAA codes have a very fast encoder structure. Using density evolution on their associated protographs, we find examples of rate-lJ2 ARAA codes with maximum variable node degree 4 for which a minimum bit-SNR as low as 0.21 dB from the channel capacity limit can be achieved as the block size goes to infinity. Such a low threshold cannot be achieved by RA or Irregular RA (IRA) or unstructured irregular LDPC codes with the same constraint on the maximum variable node degree. Furthermore by puncturing the accumulators we can construct families of higher rate ARAA codes with thresholds that stay close to their respective channel capacity thresholds uniformly. Iterative decoding simulation results show comparable performance with the best-known LDPC codes but with very low error floor even at moderate block sizes.
NASA Technical Reports Server (NTRS)
Chu, Julio; Luckring, James M.
1996-01-01
An experimental wind tunnel test of a 65 deg delta wing model with interchangeable leading edges was conducted in the Langley National Transonic Facility (NTF). The objective was to investigate the effects of Reynolds and Mach numbers on slender-wing leading-edge vortex flows with four values of wing leading-edge bluntness. Experimentally obtained pressure data are presented without analysis in tabulated and graphical formats across a Reynolds number range of 6 x 10(exp 6) to 120 x 10(exp 6) at a Mach number of 0.85 and across a Mach number range of 0.4 to 0.9 at Reynolds numbers of 6 x 10(exp 6) and 60 x 10(exp 6). Normal-force and pitching-moment coefficient plots for these Reynolds number and Mach number ranges are also presented.
NASA Astrophysics Data System (ADS)
Baars, Woutijn J.; Hutchins, Nicholas; Marusic, Ivan
2015-11-01
Interactions between small- and large-scale motions are inherent in the near-wall dynamics of wall-bounded flows. We here examine the scale-interaction embedded within the streamwise velocity component. Data were acquired using hot-wire anemometry in ZPG turbulent boundary layers, for Reynolds numbers ranging from Reτ ≡ δUτ / ν ~ 2800 to 22800. After first decomposing velocity signals into contributions from small- and large-scales, we then represent the time-varying small-scale energy with time series of its instantaneous amplitude and instantaneous frequency, via a wavelet-based method. Features of the scale-interaction are inferred from isocorrelation maps, formed by correlating the large-scale velocity with its concurrent small-scale amplitude and frequency. Below the onset of the log-region, the physics constitutes aspects of amplitude modulation and frequency modulation. Time shifts, associated with the correlation extrema--representing the lead/lag of the small-scale signatures relative to the large-scales--are shown to be governed by inner-scaling. Wall-normal trends of time shifts are explained by considering the arrangement of scales in the log- and intermittent-regions, and how they relate to stochastic top-down and bottom-up processes.
Bergfelder-Drüing, Sarah; Grosse-Brinkhaus, Christine; Lind, Bianca; Erbe, Malena; Schellander, Karl; Simianer, Henner; Tholen, Ernst
2015-01-01
The number of piglets born alive (NBA) per litter is one of the most important traits in pig breeding due to its influence on production efficiency. It is difficult to improve NBA because the heritability of the trait is low and it is governed by a high number of loci with low to moderate effects. To clarify the biological and genetic background of NBA, genome-wide association studies (GWAS) were performed using 4,012 Large White and Landrace pigs from herdbook and commercial breeding companies in Germany (3), Austria (1) and Switzerland (1). The animals were genotyped with the Illumina PorcineSNP60 BeadChip. Because of population stratifications within and between breeds, clusters were formed using the genetic distances between the populations. Five clusters for each breed were formed and analysed by GWAS approaches. In total, 17 different significant markers affecting NBA were found in regions with known effects on female reproduction. No overlapping significant chromosome areas or QTL between Large White and Landrace breed were detected. PMID:25781935
Bergfelder-Drüing, Sarah; Grosse-Brinkhaus, Christine; Lind, Bianca; Erbe, Malena; Schellander, Karl; Simianer, Henner; Tholen, Ernst
2015-01-01
The number of piglets born alive (NBA) per litter is one of the most important traits in pig breeding due to its influence on production efficiency. It is difficult to improve NBA because the heritability of the trait is low and it is governed by a high number of loci with low to moderate effects. To clarify the biological and genetic background of NBA, genome-wide association studies (GWAS) were performed using 4,012 Large White and Landrace pigs from herdbook and commercial breeding companies in Germany (3), Austria (1) and Switzerland (1). The animals were genotyped with the Illumina PorcineSNP60 BeadChip. Because of population stratifications within and between breeds, clusters were formed using the genetic distances between the populations. Five clusters for each breed were formed and analysed by GWAS approaches. In total, 17 different significant markers affecting NBA were found in regions with known effects on female reproduction. No overlapping significant chromosome areas or QTL between Large White and Landrace breed were detected. PMID:25781935
Wang, Wei; Qin, Yingxiong; Xiao, Yu; Zhong, Lijing; Wu, Chao; Wang, Zhen; Wan, Wen; Tang, Xiahui
2016-07-20
Large-Fresnel-number unstable-waveguide hybrid resonators employing spherical resonator mirrors suffer from spherical aberration, which adversely affects beam quality and alignment sensitivity. In this paper, we present experimental and numerical wave-optics simulations of the beam characteristics of a negative-branch hybrid resonator having parabolic mirrors with a large equivalent Fresnel number in the unstable direction. These results are compared with a resonator using spherical mirrors. Using parabolic mirrors, the output beam has a smaller beam spot size and higher power density at the focal plane. We found that the power extraction efficiency is 3.5% higher when compared with a resonator using spherical mirrors as the cavity length was varied between -1 and 1 mm from the ideal confocal resonator. In addition, the power extraction efficiency is 5.6% higher for mirror tilt angles varied between -6 and 6 mrad. Furthermore, the output propagating field is similar to a converging wave for a spherical mirror resonator and the output beam direction deviates 3.5 mrad from the optical axis. The simulation results are in good agreement with the experimental results. PMID:27463896
NASA Astrophysics Data System (ADS)
Lin, Liangkui; Xu, Hui; An, Wei; Sheng, Weidong; Xu, Dan
2011-11-01
This paper presents a novel approach to tracking a large number of closely spaced objects (CSO) in image sequences that is based on the particle probability hypothesis density (PHD) filter and multiassignment data association. First, the particle PHD filter is adopted to eliminate most of the clutters and to estimate multitarget states. In the particle PHD filter, a noniterative multitarget estimation technique is introduced to reliably estimate multitarget states, and an improved birth particle sampling scheme is present to effectively acquire targets among clutters. Then, an integrated track management method is proposed to realize multitarget track continuity. The core of the track management is the track-to-estimation multiassignment association, which relaxes the traditional one-to-one data association restriction due to the unresolved focal plane CSO measurements. Meanwhile, a unified technique of multiple consecutive misses for track deletion is used jointly to cope with the sensitivity of the PHD filter to the missed detections and to eliminate false alarms further, as well as to initiate tracks of large numbers of CSO. Finally, results of two simulations and one experiment show that the proposed approach is feasible and efficient.
Accumulate-Repeat-Accumulate-Accumulate Codes
NASA Technical Reports Server (NTRS)
Divsalar, Dariush; Dolinar, Samuel; Thorpe, Jeremy
2007-01-01
Accumulate-repeat-accumulate-accumulate (ARAA) codes have been proposed, inspired by the recently proposed accumulate-repeat-accumulate (ARA) codes. These are error-correcting codes suitable for use in a variety of wireless data-communication systems that include noisy channels. ARAA codes can be regarded as serial turbolike codes or as a subclass of low-density parity-check (LDPC) codes, and, like ARA codes they have projected graph or protograph representations; these characteristics make it possible to design high-speed iterative decoders that utilize belief-propagation algorithms. The objective in proposing ARAA codes as a subclass of ARA codes was to enhance the error-floor performance of ARA codes while maintaining simple encoding structures and low maximum variable node degree.
Pritchard, V L; Abadía-Cardoso, A; Garza, J C
2012-09-01
Hybridization of cutthroat trout and steelhead/rainbow trout is ubiquitous where they are sympatric, either naturally or owing to introductions. The ability to detect hybridization and introgression between the two species would be greatly improved by the development of more diagnostic markers validated across the two species' many phylogenetic lineages. Here, we describe 81 novel genetic markers and associated assays for discriminating the genomes of these sister species. These diagnostic nucleotide polymorphisms were discovered by sequencing of rainbow trout expressed sequence tags (ESTs) in a diverse panel of both cutthroat trout and steelhead/rainbow trout. The resulting markers were validated in a large number of lineages of both species, including all extant subspecies of cutthroat trout and most of the lineages of rainbow trout that are found in natural sympatry with cutthroat trout or used in stocking practices. Most of these markers (79%) distinguish genomic regions for all lineages of the two species, but a small number do not reliably diagnose coastal, westslope and/or other subspecies of cutthroat trout. Surveys of natural populations and hatchery strains of trout and steelhead found rare occurrences of the alternative allele, which may be due to either previous introgression or shared polymorphism. The availability of a large number of genetic markers for distinguishing genomic regions originating in these sister species will allow the detection of both recent and more distant hybridization events, facilitate the study of the evolutionary dynamics of hybridization and provide a powerful set of tools for the conservation and management of both species. PMID:22591214
NASA Astrophysics Data System (ADS)
Nejadmalayeri, Alireza; Vezolainen, Alexei; Vasilyev, Oleg V.
2011-11-01
With the recent development of parallel adaptive wavelet collocation method, adaptive numerical simulations of high Reynolds number turbulent flows have become feasible. The integration of turbulence modeling of different fidelity with adaptive wavelet methods results in a hierarchical approach for modeling and simulating turbulent flows in which all or most energetic parts of coherent eddies are dynamically resolved on self-adaptive computational grids, while modeling the effect of the unresolved incoherent or less energetic modes. This talk is the first attempt to estimate how spatial modes of both Coherent Vortex Simulations (CVS) and Stochastic Coherent Adaptive Large Eddy Simulations (SCALES) scale with Reynolds number. The computational complexity studies for both CVS and SCALES of linearly forced homogeneous turbulence are performed at effective non-adaptive resolutions of 2563, 5123, 10243, and 20483 corresponding to approximate Reλ of 70, 120, 190, 320. The details of the simulations are discussed and the results of compression achieved by CVS and SCALES as well as scalability studies of the parallel algorithm for the aforementioned Taylor micro-scale Reynolds numbers are presented. This work was supported by NSF under grant No. CBET-0756046.
Michael, C A; Tanaka, K; Vyacheslavov, L; Sanin, A; Kawahata, K
2015-09-01
An analysis method for unfolding the spatially resolved wave-number spectrum and phase velocity from the 2D CO2 laser phase contrast imaging system on the large helical device is described. This is based on the magnetic shear technique which identifies propagation direction from 2D spatial Fourier analysis of images detected by a 6 × 8 detector array. Because the strongest modes have wave-number at the lower end of the instrumental k range, high resolution spectral techniques are necessary to clearly resolve the propagation direction and hence the spatial distribution of fluctuations along the probing laser beam. Multiple-spatial point cross-correlation averaging is applied before calculating the spatial power spectrum. Different methods are compared, and it is found that the maximum entropy method (MEM) gives best results. The possible generation of artifacts from the over-narrowing of spectra are investigated and found not to be a significant problem. The spatial resolution Δρ (normalized radius) around the peak wave-number, for conventional Fourier analysis, is ∼0.5, making physical interpretation difficult, while for MEM, Δρ ∼ 0.1. PMID:26429439
Michael, C. A.; Tanaka, K.; Kawahata, K.; Vyacheslavov, L.; Sanin, A.
2015-09-15
An analysis method for unfolding the spatially resolved wave-number spectrum and phase velocity from the 2D CO{sub 2} laser phase contrast imaging system on the large helical device is described. This is based on the magnetic shear technique which identifies propagation direction from 2D spatial Fourier analysis of images detected by a 6 × 8 detector array. Because the strongest modes have wave-number at the lower end of the instrumental k range, high resolution spectral techniques are necessary to clearly resolve the propagation direction and hence the spatial distribution of fluctuations along the probing laser beam. Multiple-spatial point cross-correlation averaging is applied before calculating the spatial power spectrum. Different methods are compared, and it is found that the maximum entropy method (MEM) gives best results. The possible generation of artifacts from the over-narrowing of spectra are investigated and found not to be a significant problem. The spatial resolution Δρ (normalized radius) around the peak wave-number, for conventional Fourier analysis, is ∼0.5, making physical interpretation difficult, while for MEM, Δρ ∼ 0.1.
NASA Astrophysics Data System (ADS)
Tanaka, Masaaki; Ohshima, Hiroyuki
Flow induced vibration in primary cooling system of the Japan Sodium cooled Fast Reactor (JSFR) has been investigated. The primary cooling system consists of a large diameter pipe and a pipe elbow with short curvature radius corresponding to its diameter (short-elbow). Flow-induced vibration by flow through the short-elbow is an important issue in design study of the JSFR, because it may affect to structural integrity of the piping. In this paper, numerical simulations for several pipe elbows with different pipe diameters and curvature radii in literature were conducted at Reynolds number conditions from Re=500 to 1.47x107 to investigate unsteady flow behavior through the short-elbow, including validation study of an in-house LES code (MUGTHES). Numerical results in each condition were compared with the experimental results in literature. Unsteady flow characteristics and pressure fluctuation generation mechanism in the short-elbow were clarified in relation to the large-scale eddy motion.
NASA Astrophysics Data System (ADS)
Guerrero, M.; Li, X. Allen
2003-10-01
Numerous studies of early-stage breast cancer treated with breast conserving surgery (BCS) and radiotherapy (RT) have been published in recent years. Both external beam radiotherapy (EBRT) and/or brachytherapy (BT) with different fractionation schemes are currently used. The present RT practice is largely based on empirical experience and it lacks a reliable modelling tool to compare different RT modalities or to design new treatment strategies. The purpose of this work is to derive a plausible set of radiobiological parameters that can be used for RT treatment planning. The derivation is based on existing clinical data and is consistent with the analysis of a large number of published clinical studies on early-stage breast cancer. A large number of published clinical studies on the treatment of early breast cancer with BCS plus RT (including whole breast EBRT with or without a boost to the tumour bed, whole breast EBRT alone, brachytherapy alone) and RT alone are compiled and analysed. The linear quadratic (LQ) model is used in the analysis. Three of these clinical studies are selected to derive a plausible set of LQ parameters. The potential doubling time is set a priori in the derivation according to in vitro measurements from the literature. The impact of considering lower or higher Tpot is investigated. The effects of inhomogeneous dose distributions are considered using clinically representative dose volume histograms. The derived LQ parameters are used to compare a large number of clinical studies using different regimes (e.g., RT modality and/or different fractionation schemes with different prescribed dose) in order to validate their applicability. The values of the equivalent uniform dose (EUD) and biologically effective dose (BED) are used as a common metric to compare the biological effectiveness of each treatment regime. We have obtained a plausible set of radiobiological parameters for breast cancer: agr = 0.3 Gy-1, agr/bgr = 10 Gy and sub
Qiao, Ying; Liu, Xudong; Harvard, Chansonette; Nolin, Sarah L; Brown, W Ted; Koochek, Maryam; Holden, Jeanette JA; Lewis, ME Suzanne; Rajcan-Separovic, Evica
2007-01-01
Background Genomic copy number variants (CNVs) involving >1 kb of DNA have recently been found to be widely distributed throughout the human genome. They represent a newly recognized form of DNA variation in normal populations, discovered through screening of the human genome using high-throughput and high resolution methods such as array comparative genomic hybridization (array-CGH). In order to understand their potential significance and to facilitate interpretation of array-CGH findings in constitutional disorders and cancers, we studied 27 normal individuals (9 Caucasian; 9 African American; 9 Hispanic) using commercially available 1 Mb resolution BAC array (Spectral Genomics). A selection of CNVs was further analyzed by FISH and real-time quantitative PCR (RT-qPCR). Results A total of 42 different CNVs were detected in 27 normal subjects. Sixteen (38%) were not previously reported. Thirteen of the 42 CNVs (31%) contained 28 genes listed in OMIM. FISH analysis of 6 CNVs (4 previously reported and 2 novel CNVs) in normal subjects resulted in the confirmation of copy number changes for 1 of 2 novel CNVs and 2 of 4 known CNVs. Three CNVs tested by FISH were further validated by RT-qPCR and comparable data were obtained. This included the lack of copy number change by both RT-qPCR and FISH for clone RP11-100C24, one of the most common known copy number variants, as well as confirmation of deletions for clones RP11-89M16 and RP5-1011O17. Conclusion We have described 16 novel CNVs in 27 individuals. Further study of a small selection of CNVs indicated concordant and discordant array vs. FISH/RT-qPCR results. Although a large number of CNVs has been reported to date, quantification using independent methods and detailed cellular and/or molecular assessment has been performed on a very small number of CNVs. This information is, however, very much needed as it is currently common practice to consider CNVs reported in normal subjects as benign changes when detected in
NASA Astrophysics Data System (ADS)
McConnell, R.; Gabrielse, G.; Kolthammer, W. S.; Richerme, P.; Müllers, A.; Walz, J.; Grzonka, D.; Zielinski, M.; Fitzakerley, D.; George, M. C.; Hessels, E. A.; Storry, C. H.; Weel, M.;
2016-03-01
Lasers are used to control the production of highly excited positronium atoms (Ps*). The laser light excites Cs atoms to Rydberg states that have a large cross section for resonant charge-exchange collisions with cold trapped positrons. For each trial with 30 million trapped positrons, more than 700 000 of the created Ps* have trajectories near the axis of the apparatus, and are detected using Stark ionization. This number of Ps* is 500 times higher than realized in an earlier proof-of-principle demonstration (2004 Phys. Lett. B 597 257). A second charge exchange of these near-axis Ps* with trapped antiprotons could be used to produce cold antihydrogen, and this antihydrogen production is expected to be increased by a similar factor.
NASA Astrophysics Data System (ADS)
Korkusuz Öztürk, Yasemin; Meral Özel, Nurcan; Özbakir, Ali Değer
2015-12-01
We invert the present day states of stresses for five apparent earthquake clusters in the Northern branch of the North Anatolian Fault in the Sea of Marmara. As the center of the Sea of Marmara is prone to a devastating earthquake within a seismic gap between these selected clusters, sensitive analyses of the understanding of the stress and strain characteristics of the region are all-important. We use high quality P and S phases, and P-wave first motion polarities from 398 earthquakes with ML ≥ 1.5 using at least 10 P-wave first motion polarities (FMPs), and a maximum of 1 inconsistent station, obtained from a total of 105 seismic stations, including 5 continuous OBSs. We report here on large numbers of simultaneously determined individual fault plane solutions (FPSs), and orientations of principal stress axes, which previously have not been determined with any confidence from the basins of the Sea of Marmara and prominent fault branches. We find NE-SW trending transtensional stress structures, predominantly in the earthquake clusters of the Eastern Tekirdağ Basin, Eastern Çınarcık Basin, Yalova and Gemlik areas. We infer that a dextral strike-slip deformation exist in the Eastern Ganos Offshore cluster. Furthermore, we analyze FPSs of four ML ≥ 4.0 earthquakes, occurred in seismically quiet regions after 1999 Izmit earthquake. Stress tensor solutions from a cluster of small events that we have obtained, correlate with FPSs of these moderate size events as a demonstration of the effectiveness of the small earthquakes in the derivation of states of local stresses. Consequently, our analyses of seismicity and large numbers of FPSs using the densest seismic network of Turkey contribute to better understanding of the present states of the stresses and seismotectonics of the Sea of Marmara.
NASA Astrophysics Data System (ADS)
Zhong, Jin-Qiang; Li, Hui-Min; Wang, Xue-Ying
2015-11-01
We present measurements of the azimuthal orientation θ (t) of the large-scale circulation (LSC) for turbulent Rayleigh-Bénard convection in the presence of week rotations Ω . Linear retrograde rotations of the LSC circulating plane are observed over the entire Rossby-number range (1 <= Ro <= 300) studied. When the Ro increases, the ratio of the retrograde rotation rate, γ = - < . θ > / Ω remains nearly a constant 0.12 in the range of (1 <= Ro <= 80) and starts to increases when Ro > 80 . When Ro ~= 300 , γ approaches a value of 0.36 close to the prediction from previous theoretical models. In a background of linear rotations, erratic changes in θ (t) accompanied by decreasing in the LSC amplitude δ are observed. These small- δ events give rise to the increasing γ with very high Ro numbers (80 <= Ro <= 300). In this range, the diffusivity of θ is proportional to δ-2 . Moreover, the occurrence frequency of the small- δ events, and their average duration are independent on Ro. We propose a model to include additional viscous damping for the LSC azimuthal motion due to turbulent viscosity and provide theoretical interpretations of the experimental results. Work supported by NSFC Grant No. 11202151.
NASA Astrophysics Data System (ADS)
Patra, Bishnubrata; Peng, Chien-Chung; Liao, Wei-Hao; Lee, Chau-Hwang; Tung, Yi-Chung
2016-02-01
Three-dimensional (3D) tumor spheroid possesses great potential as an in vitro model to improve predictive capacity for pre-clinical drug testing. In this paper, we combine advantages of flow cytometry and microfluidics to perform drug testing and analysis on a large number (5000) of uniform sized tumor spheroids. The spheroids are formed, cultured, and treated with drugs inside a microfluidic device. The spheroids can then be harvested from the device without tedious operation. Due to the ample cell numbers, the spheroids can be dissociated into single cells for flow cytometry analysis. Flow cytometry provides statistical information in single cell resolution that makes it feasible to better investigate drug functions on the cells in more in vivo-like 3D formation. In the experiments, human hepatocellular carcinoma cells (HepG2) are exploited to form tumor spheroids within the microfluidic device, and three anti-cancer drugs: Cisplatin, Resveratrol, and Tirapazamine (TPZ), and their combinations are tested on the tumor spheroids with two different sizes. The experimental results suggest the cell culture format (2D monolayer vs. 3D spheroid) and spheroid size play critical roles in drug responses, and also demonstrate the advantages of bridging the two techniques in pharmaceutical drug screening applications.
Patra, Bishnubrata; Peng, Chien-Chung; Liao, Wei-Hao; Lee, Chau-Hwang; Tung, Yi-Chung
2016-01-01
Three-dimensional (3D) tumor spheroid possesses great potential as an in vitro model to improve predictive capacity for pre-clinical drug testing. In this paper, we combine advantages of flow cytometry and microfluidics to perform drug testing and analysis on a large number (5000) of uniform sized tumor spheroids. The spheroids are formed, cultured, and treated with drugs inside a microfluidic device. The spheroids can then be harvested from the device without tedious operation. Due to the ample cell numbers, the spheroids can be dissociated into single cells for flow cytometry analysis. Flow cytometry provides statistical information in single cell resolution that makes it feasible to better investigate drug functions on the cells in more in vivo-like 3D formation. In the experiments, human hepatocellular carcinoma cells (HepG2) are exploited to form tumor spheroids within the microfluidic device, and three anti-cancer drugs: Cisplatin, Resveratrol, and Tirapazamine (TPZ), and their combinations are tested on the tumor spheroids with two different sizes. The experimental results suggest the cell culture format (2D monolayer vs. 3D spheroid) and spheroid size play critical roles in drug responses, and also demonstrate the advantages of bridging the two techniques in pharmaceutical drug screening applications. PMID:26877244
Schmid, K J; Nigro, L; Aquadro, C F; Tautz, D
1999-01-01
We present a survey of nucleotide polymorphism of three novel, rapidly evolving genes in populations of Drosophila melanogaster and D. simulans. Levels of silent polymorphism are comparable to other loci, but the number of replacement polymorphisms is higher than that in most other genes surveyed in D. melanogaster and D. simulans. Tests of neutrality fail to reject neutral evolution with one exception. This concerns a gene located in a region of high recombination rate in D. simulans and in a region of low recombination rate in D. melanogaster, due to an inversion. In the latter case it shows a very low number of polymorphisms, presumably due to selective sweeps in the region. Patterns of nucleotide polymorphism suggest that most substitutions are neutral or nearly neutral and that weak (positive and purifying) selection plays a significant role in the evolution of these genes. At all three loci, purifying selection of slightly deleterious replacement mutations appears to be more efficient in D. simulans than in D. melanogaster, presumably due to different effective population sizes. Our analysis suggests that current knowledge about genome-wide patterns of nucleotide polymorphism is far from complete with respect to the types and range of nucleotide substitutions and that further analysis of differences between local populations will be required to understand the forces more completely. We note that rapidly diverging and nearly neutrally evolving genes cannot be expected only in the genome of Drosophila, but are likely to occur in large numbers also in other organisms and that their function and evolution are little understood so far. PMID:10581279
NASA Astrophysics Data System (ADS)
Mohammed, Ali Ibrahim Ali
The understanding and treatment of brain disorders as well as the development of intelligent machines is hampered by the lack of knowledge of how the brain fundamentally functions. Over the past century, we have learned much about how individual neurons and neural networks behave, however new tools are critically needed to interrogate how neural networks give rise to complex brain processes and disease conditions. Recent innovations in molecular techniques, such as optogenetics, have enabled neuroscientists unprecedented precision to excite, inhibit and record defined neurons. The impressive sensitivity of currently available optogenetic sensors and actuators has now enabled the possibility of analyzing a large number of individual neurons in the brains of behaving animals. To promote the use of these optogenetic tools, this thesis integrates cutting edge optogenetic molecular sensors which is ultrasensitive for imaging neuronal activity with custom wide field optical microscope to analyze a large number of individual neurons in living brains. Wide-field microscopy provides a large field of view and better spatial resolution approaching the Abbe diffraction limit of fluorescent microscope. To demonstrate the advantages of this optical platform, we imaged a deep brain structure, the Hippocampus, and tracked hundreds of neurons over time while mouse was performing a memory task to investigate how those individual neurons related to behavior. In addition, we tested our optical platform in investigating transient neural network changes upon mechanical perturbation related to blast injuries. In this experiment, all blasted mice show a consistent change in neural network. A small portion of neurons showed a sustained calcium increase for an extended period of time, whereas the majority lost their activities. Finally, using optogenetic silencer to control selective motor cortex neurons, we examined their contributions to the network pathology of basal ganglia related to
Baars, Annemarie; Oosting, Annemarie; Engels, Eefje; Kegler, Diane; Kodde, Andrea; Schipper, Lidewij; Verkade, Henkjan J; van der Beek, Eline M
2016-06-01
Epidemiological studies have demonstrated protective effects of breast-feeding on childhood obesity. Differences between human milk and infant milk formula (IMF) in dietary lipid structure may contribute to this effect. In our mouse model, feeding a diet containing large lipid droplets coated with phospholipids (PL) (Nuturis®; PL of milk fat globule membrane (MFGM) fraction origin) in early life protected against excessive body fat accumulation following a diet challenge in adult life. We now set out to determine the relevance of increased droplet size and/or MFGM lipid droplet coating to the observed anti-obesogenic effects in adult life. From day 16 to 42, male mouse pups were exposed to diets with small (S) or large (L) lipid droplets (0·3 v. 2·9 µm average mode diameter, respectively), either without MFGM or with MFGM coating around the lipid droplet, resulting in four groups: S (control diet), L, Scoating and Lcoating (Nuturis® IMF diet). Mice were subsequently challenged with a Western-style diet until dissection at postnatal day 98. A non-challenged group served as reference (REF). We repeatedly determined body composition between postnatal day 42 and 98. At day 98 plasma and gene expression measurements were performed. Only the Nuturis® IMF diet (Lcoating) in early life containing MFGM-coated large lipid droplets reduced body fat mass to a level comparable with the REF group. These data support the notion that the structural aspects of lipids in human milk, for example, both lipid droplet size as well as the MFGM coating, may contribute to its reported protective effect against obesity in later life. PMID:27040581
Lotocki, George; de Rivero Vaccari, Juan Pablo; Perez, Enrique R.; Sanchez-Molano, Juliana; Furones-Alonso, Ofelia; Bramlett, Helen M.
2009-01-01
Abstract We investigated the temporal and regional profile of blood-brain barrier (BBB) permeability to both large and small molecules after moderate fluid percussion (FP) brain injury in rats and determined the effects of post-traumatic modest hypothermia (33°C/4 h) on these vascular perturbations. The visible tracers biotin-dextrin-amine 3000 (BDA-3K, 3 kDa) and horseradish peroxidase (HRP, 44 kDa) were injected intravenously at 4 h or 3 or 7 days post-TBI. At 30 min after the tracer infusion, both small and large molecular weight tracers were detected in the contusion area as well as remote regions adjacent to the injury epicenter in both cortical and hippocampal structures. In areas adjacent to the contusion site, increased permeability to the small molecular weight tracer (BDA-3K) was evident at 4 h post-TBI and remained visible after 7 days survival. In contrast, the larger tracer molecule (HRP) appeared in these remote areas at acute permeable sites but was not detected at later post-traumatic time periods. A regionally specific relationship was documented at 3 days between the late-occurring permeability changes observed with BDA-3K and the accumulation of CD68-positive macrophages. Mild hypothermia initiated 30 min after TBI reduced permeability to both large and small tracers and the infiltration of CD68-positive cells. These results indicate that moderate brain injury produces temperature-sensitive acute, as well as more long-lasting vascular perturbations associated with secondary injury mechanisms. PMID:19558276
Duan, Ying-Liang; Ye, Han-Qing; Zavala, Anamaria G.; Yang, Cui-Qing; Miao, Ling-Feng; Fu, Bi-Shi; Seo, Keun Seok; Davrinche, Christian
2014-01-01
ABSTRACT After infection, human cytomegalovirus (HCMV) persists for life. Primary infections and reactivation of latent virus can both result in congenital infection, a leading cause of central nervous system birth defects. We previously reported long-term HCMV infection in the T98G glioblastoma cell line (1). HCMV infection has been further characterized in T98Gs, emphasizing the presence of HCMV DNA over an extended time frame. T98Gs were infected with either HCMV Towne or AD169-IE2-enhanced green fluorescent protein (eGFP) strains. Towne infections yielded mixed IE1 antigen-positive and -negative (Ag+/Ag−) populations. AD169-IE2-eGFP infections also yielded mixed populations, which were sorted to obtain an IE2− (Ag−) population. Viral gene expression over the course of infection was determined by immunofluorescent analysis (IFA) and reverse transcription-PCR (RT-PCR). The presence of HCMV genomes was determined by PCR, nested PCR (n-PCR), and fluorescence in situ hybridization (FISH). Compared to the HCMV latency model, THP-1, Towne-infected T98Gs expressed IE1 and latency-associated transcripts for longer periods, contained many more HCMV genomes during early passages, and carried genomes for a greatly extended period of passaging. Large numbers of HCMV genomes were also found in purified Ag− AD169-infected cells for the first several passages. Interestingly, latency transcripts were observed from very early times in the Towne-infected cells, even when IE1 was expressed at low levels. Although AD169-infected Ag− cells expressed no detectable levels of either IE1 or latency transcripts, they also maintained large numbers of genomes within the cell nuclei for several passages. These results identify HCMV-infected T98Gs as an attractive new model in the study of the long-term maintenance of virus genomes in the context of neural cell types. IMPORTANCE Our previous work showed that T98G glioblastoma cells were semipermissive to HCMV infection; virus