Constructing explicit magnetic analogies for the dynamics of glass forming liquids
Stevenson, Jacob D.; Walczak, Aleksandra M.; Hall, Randall W.; Wolynes, Peter G.
2008-01-01
By defining a spatially varying replica overlap parameter for a supercooled liquid referenced to an ensemble of fiducial liquid state configurations, we explicitly construct a constrained replica free energy functional that maps directly onto an Ising Hamiltonian with both random fields and random interactions whose statistics depend on the liquid structure. Renormalization group results for random magnets when combined with these statistics for the Lennard-Jones glass suggest that discontinuous replica symmetry breaking would occur if a liquid with short range interactions could be equilibrated at a sufficiently low temperature where its mean field configurational entropy would vanish, even though the system strictly retains a finite configurational entropy. PMID:19026064
Wakimoto realizations of current algebras: an explicit construction
de Boer, Jan; Feher, Laszlo
1996-11-12
A generalized Wakimoto realization of $\\widehat\\cal G_K$ can be associated with each parabolic subalgebra $\\cal P=(\\cal G_0 +\\cal G_+)$ of a simple Lie algebra $\\cal G$ according to an earlier proposal by Feigin and Frenkel. In this paper the proposal is made explicit by developing the construction of Wakimoto realizations from a simple but unconventional viewpoint. An explicit formula is derived for the Wakimoto current first at the Poisson bracket level by Hamiltonian symmetry reduction of the WZNW model. The quantization is then performed by normal ordering the classical formula and determining the required quantum correction for it to generate $\\widehat\\cal G_K$ by means of commutators. The affine-Sugawara stress-energy tensor is verified to have the expected quadratic form in the constituents, which are symplectic bosons belonging to $\\cal G_+$ and a current belonging to $\\cal G_0$. The quantization requires a choice of special polynomial coordinates on the big cell of the flag manifold $P\\backslash G$. The effect of this choice is investigated in detail by constructing quantum coordinate transformations. Finally, the explicit form of the screening charges for each generalized Wakimoto realization is determined, and some applications are briefly discussed.
Multi-fidelity construction of explicit boundaries: Application to aeroelasticity
NASA Astrophysics Data System (ADS)
Dribusch, Christoph
Wings, control surfaces and rotor blades subject to aerodynamic forces may exhibit aeroelastic instabilities such as flutter, divergence and limit cycle oscillations which generally reduce their life and functionality. This possibility of instability must be taken into account during the design process and numerical simulation models may be used to predict aeroelastic stability. Aeroelastic stability is a design requirement that encompasses several difficulties also found in other areas of design. For instance, the large computational time associated with stability analysis is also found in computational fluid dynamics (CFD) models. It is a major hurdle in numerical optimization and reliability analysis, which generally require large numbers of call to the simulation code. Similarly, the presence of bifurcations and discontinuities is also encountered in structural impact analysis based on nonlinear dynamic simulations and renders traditional approximation techniques such as Kriging ineffective. Finally, for a given component or system, aeroelastic instability is only one of multiple failure modes which must be accounted for during design and reliability studies. To address the above challenges, this dissertation proposes a novel algorithm to predict, over a range of parameters, the qualitative outcomes (pass/fail) of simulations based on relatively few, classified (pass/fail) simulation results. This is different from traditional approximation techniques that seek to predict simulation outcomes quantitatively, for example by fitting a response surface. The predictions of the proposed algorithm are based on the theory of support vector machines (SVM), a machine learning method originated in the field of pattern recognition. This process yields an analytical function that explicitly defines the boundary between feasible and infeasible regions of the parameter space and has the ability to reproduce nonlinear, disjoint boundaries in n dimensions. Since training the
ERIC Educational Resources Information Center
Gutierrez, Xavier
2013-01-01
Grammaticality judgment tests (GJTs) have been, and continue to be, frequently used in the field of SLA as a measure of learners' linguistic ability in the second language (L2). However, only a few studies have examined their construct validity as measures of implicit and explicit knowledge (Bowles, 2011; R. Ellis, 2005), and even fewer have…
"Co-Constructing" Explicit L2 Knowledge with High School Spanish Learners through Guided Induction
ERIC Educational Resources Information Center
Toth, Paul D.; Wagner, Elvis; Moranski, Kara
2013-01-01
This article documents how second language (L2) Spanish learners in an American high school formulated explicit grammar rules during three inductive lessons on the pronominal clitic "se." Following Adair-Hauck "et al." (2010), each lesson first presented a property of "se" within a narrative text, and then had learners inductively "Co-construct"…
NASA Astrophysics Data System (ADS)
Chen, Y. Y.; Chen, S. H.; Zhao, W.
2017-07-01
An improved procedure for perturbation method is presented for constructing homoclinic solutions of strongly nonlinear self-excited oscillators. Compared with current perturbation methods based on nonlinear time transformations, the preference of the present method is that the explicit solutions, in respect to the original time variable, can be derived. In the paper, the equivalence and unified perturbation procedure with nonlinear time transformations, by which implicit solutions can be derived at nonlinear time scales, are firstly presented. Then an explicit generating homoclinic solution for power-law strongly nonlinear oscillator is derived with proposed hyperbolic function balance procedure. An approximation scheme is presented to improve the perturbation procedure and the explicit expression for nonlinear time transformation can be achieved. Applications and comparisons with other methods are performed to assess the advantage of the present method.
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.
Holography as a highly efficient renormalization group flow. II. An explicit construction
NASA Astrophysics Data System (ADS)
Behr, Nicolas; Mukhopadhyay, Ayan
2016-07-01
We complete the reformulation of the holographic correspondence as a highly efficient renormalization group (RG) flow that can also determine the UV data in the field theory in the strong-coupling and large-N limit. We introduce a special way to define operators at any given scale in terms of appropriate coarse-grained collective variables, without requiring the use of the elementary fields. The Wilsonian construction is generalized by promoting the cutoff to a functional of these collective variables. We impose three criteria to determine the coarse-graining. The first criterion is that the effective Ward identities for local conservation of energy, momentum, etc. should preserve their standard forms, but in new scale-dependent background metric and sources which are functionals of the effective single-trace operators. The second criterion is that the scale-evolution equations of the operators in the actual background metric should be state-independent, implying that the collective variables should not explicitly appear in them. The final required criterion is that the end point of the scale-evolution of the RG flow can be transformed to a fixed point corresponding to familiar nonrelativistic equations with a finite number of parameters, such as incompressible nonrelativistic Navier-Stokes, under a certain universal rescaling of the scale and of the time coordinate. Using previous work, we explicitly show that in the hydrodynamic limit each such highly efficient RG flow reproduces a unique classical gravity theory with precise UV data that satisfy our IR criterion and also lead to regular horizons in the dual geometries. We obtain the explicit coarse-graining which reproduces Einstein's equations. In a simple example, we are also able to construct a low-energy effective action and compute the beta function. Finally, we show how our construction can be interpolated with the traditional Wilsonian RG flow at a suitable scale and can be used to develop new
From Cycle Rooted Spanning Forests to the Critical Ising Model: an Explicit Construction
NASA Astrophysics Data System (ADS)
de Tilière, Béatrice
2013-04-01
Fisher established an explicit correspondence between the 2-dimensional Ising model defined on a graph G and the dimer model defined on a decorated version {{G}} of this graph (Fisher in J Math Phys 7:1776-1781, 1966). In this paper we explicitly relate the dimer model associated to the critical Ising model and critical cycle rooted spanning forests (CRSFs). This relation is established through characteristic polynomials, whose definition only depends on the respective fundamental domains, and which encode the combinatorics of the model. We first show a matrix-tree type theorem establishing that the dimer characteristic polynomial counts CRSFs of the decorated fundamental domain {{G}_1}. Our main result consists in explicitly constructing CRSFs of {{G}_1} counted by the dimer characteristic polynomial, from CRSFs of G 1, where edges are assigned Kenyon's critical weight function (Kenyon in Invent Math 150(2):409-439, 2002); thus proving a relation on the level of configurations between two well known 2-dimensional critical models.
Østvik, Leni; Eikeseth, Svein; Klintwall, Lars
2012-01-01
This study replicated and extended Wright (2006) and Whitehurst, Ironsmith, and Goldfein (1974) by examining whether preschool aged children would increase their use of passive grammatical voice rather than using the more age-appropriate active grammatical construction when the former was modeled by an adult. Results showed that 5 of the 6 participants began using the passive voice after this verbal behavior had been modeled. For 3 of the participants, this change was large. The change occurred even though the adult model explicitly rewarded the participant with praise and stickers for using the active voice, while providing no praise or stickers for using the passive form that was modeled. For 1 participant, the modeling procedure had no effect on use of the passive voice. These results indicate a strong automatic reinforcement effect of achieving parity with the grammatical structures used by adults, compared to the effects of explicit reinforcement by the adult. This might help to explain why children acquire grammatical structures prevalent in their language community apparently without explicit instruction. PMID:22754105
Raising the Pedagogical Bar: Teachers' Co-Construction of Explicit Teaching
ERIC Educational Resources Information Center
O'Neill, Shirley; Geoghegan, Deborah; Petersen, Shauna
2013-01-01
Recent shifts in the conceptualization of effective literacy teaching have focused on the need for teachers to make teaching explicit (Edwards-Groves, 2010; Purcell-Gates, Duke, & Martineau, 2007; Rosenshine, 1986) or in Hattie's (2005) terms, learning "visible". Research has shown that the analysis of classroom interactive…
SUPERCONDUCTING HELICAL SNAKE MAGNETS: CONSTRUCTION AND MEASUREMENTS.
MACKAY,W.W.
1999-05-17
In order to collide polarized protons, the RHIC project will have two snakes in each ring and four rotators around each of two interaction regions. Two snakes on opposite sides of each ring can minimize depolarization during acceleration by keeping the spin tune at a half. Since the spin direction is normally along the vertical direction in a flat ring, spin rotators must be used around an interaction point to have longitudinal polarization in a collider experiment. Each snake or rotator will be composed of four helical dipoles to provide the required rotation of spin with minimal transverse orbit excursions in a compact length of 10m. The basic helical dipole is a superconducting magnet producing a transverse dipole field which is twisted about the magnet axis through 360{degree} in a length of 2.4 m. The design and construction of the magnets is described in this paper.
On the explicit construction of Parisi landscapes in finite dimensional Euclidean spaces
NASA Astrophysics Data System (ADS)
Fyodorov, Y. V.; Bouchaud, J.-P.
2007-12-01
An N-dimensional Gaussian landscape with multiscale translation-invariant logarithmic correlations has been constructed, and the statistical mechanics of a single particle in this environment has been investigated. In the limit of a high dimensional N → ∞, the free energy of the system in the thermodynamic limit coincides with the most general version of Derrida’s generalized random energy model. The low-temperature behavior depends essentially on the spectrum of length scales involved in the construction of the landscape. The construction is argued to be valid in any finite spatial dimensions N ≥1.
NASA Technical Reports Server (NTRS)
Mickens, Ronald E.
1989-01-01
A family of conditionally stable, forward Euler finite difference equations can be constructed for the simplest equation of Schroedinger type, namely u sub t - iu sub xx. Generalization of this result to physically realistic Schroedinger type equations is presented.
Roth, Fabian; Siegelmann, Hava; Douglas, Rodney J
2007-01-01
As man-made systems become more complex and autonomous, there is a growing need for novel engineering methods that offer self-construction, adaptation to the environment, and self-repair. In a step towards developing such methods, we demonstrate how a simple model multicellular organism can assemble itself by replication from a single cell and finally express a fundamental behavior: foraging. Previous studies have employed evolutionary approaches to this problem. Instead, we aim at explicit design of self-constructing and -repairing systems by hierarchical specification of elementary intracellular mechanisms via a kind of genetic code. The interplay between individual cells and the gradually increasing self-created complexity of the local structure that surrounds them causes the serial unfolding of the final functional organism. The developed structure continuously feeds back to the development process, and so the system is also capable of self-repair.
ERIC Educational Resources Information Center
Ostvik, Leni; Eikeseth, Svein; Klintwall, Lars
2012-01-01
This study replicated and extended Wright (2006) and Whitehurst, Ironsmith, and Goldfein (1974) by examining whether preschool aged children would increase their use of passive grammatical voice rather than using the more age-appropriate active grammatical construction when the former was modeled by an adult. Results showed that 5 of the 6…
Ground-state energy of the interacting Bose gas in two dimensions: An explicit construction
Beane, Silas R.
2010-12-15
The isotropic scattering phase shift is calculated for nonrelativistic bosons interacting at low energies via an arbitrary finite-range potential in d space-time dimensions. Scattering on a (d-1)-dimensional torus is then considered, and the eigenvalue equation relating the energy levels on the torus to the scattering phase shift is derived. With this technology in hand, and focusing on the case of two spatial dimensions, a perturbative expansion is developed for the ground-state energy of N identical bosons which interact via an arbitrary finite-range potential in a finite area. The leading nonuniversal effects due to range corrections and three-body forces are included. It is then shown that the thermodynamic limit of the ground-state energy in a finite area can be taken in closed form to obtain the energy per particle in the low-density expansion by explicitly summing the parts of the finite-area energy that diverge with powers of N. The leading and subleading finite-size corrections to the thermodynamic limit equation of state are also computed. Closed-form results--some well known, others perhaps not--for two-dimensional lattice sums are included in an Appendix.
Method of constructing a superconducting magnet
Satti, John A.
1981-01-01
A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.
Silva, Filipe da; Pinto, Martin Campos; Després, Bruno; Heuraux, Stéphane
2015-08-15
This work analyzes the stability of the Yee scheme for non-stationary Maxwell's equations coupled with a linear current model with density fluctuations. We show that the usual procedure may yield unstable scheme for physical situations that correspond to strongly magnetized plasmas in X-mode (TE) polarization. We propose to use first order clustered discretization of the vectorial product that gives back a stable coupling. We validate the schemes on some test cases representative of direct numerical simulations of X-mode in a magnetic fusion plasma including turbulence.
ERIC Educational Resources Information Center
Criado Sanchez, Raquel; Perez, Aquilino Sanchez; Gomez, Pascual Cantos
2010-01-01
The concepts of "explicit" and "implicit" (knowledge) are at the core of SLA studies. We take "explicit" as conscious and declarative (knowledge); "implicit" as unconscious, automatic and procedural (knowledge) (DeKeyser, 2003; R. Ellis, 2005a, 2005b, 2009; Hulstjin, 2005; Robinson, 1996; Schmidt, 1990, 1994). The importance of those concepts and…
Halleroed, Tomas Rylander, Thomas
2008-04-20
A stable hybridization of the finite-element method (FEM) and the finite-difference time-domain (FDTD) scheme for Maxwell's equations with electric and magnetic losses is presented for two-dimensional problems. The hybrid method combines the flexibility of the FEM with the efficiency of the FDTD scheme and it is based directly on Ampere's and Faraday's law. The electric and magnetic losses can be treated implicitly by the FEM on an unstructured mesh, which allows for local mesh refinement in order to resolve rapid variations in the material parameters and/or the electromagnetic field. It is also feasible to handle larger homogeneous regions with losses by the explicit FDTD scheme connected to an implicitly time-stepped and lossy FEM region. The hybrid method shows second-order convergence for smooth scatterers. The bistatic radar cross section (RCS) for a circular metal cylinder with a lossy coating converges to the analytical solution and an accuracy of 2% is achieved for about 20 points per wavelength. The monostatic RCS for an airfoil that features sharp corners yields a lower order of convergence and it is found to agree well with what can be expected for singular fields at the sharp corners. A careful convergence study with resolutions from 20 to 140 points per wavelength provides accurate extrapolated results for this non-trivial test case, which makes it possible to use as a reference problem for scattering codes that model both electric and magnetic losses.
Construction and testing of the Mirror Fusion Test Facility magnets
Kozman, T.; Shimer, D.; VanSant, J.; Zbasnik, J.
1986-08-01
This paper describes the construction and testing of the Mirror Fusion Test Facility superconducting magnet set. Construction of the first Yin Yang magnet was started in 1978. And although this particular magnet was later modified, the final construction of these magnets was not completed until 1985. When completed these 42 magnets weighed over 1200 tonnes and had a maximum stored energy of approximately 1200 MJ at full field. Together with power supplies, controls and liquid nitrogen radiation shields the cost of the fabrication of this system was over $100M. General Dynamics/Convair Division was responsible for the system design and the fabrication of 20 of the magnets. This contract was the largest single procurement action at the Lawrence Livermore National Laboratory. During the PACE acceptance tests, the 26 major magnets were operated at full field for more than 24 hours while other MFTF subsystems were tested. From all of the data, the magnets operated to the performance specifications. For physics operation in the future, additional helium and nitrogen leak checking and repair will be necessary. In this report we will discuss the operation and testing of the MFTF Magnet System, the world's largest superconducting magnet set built to date. The topics covered include a schedule of the major events, summary of the fabrication work, summary of the installation work, summary of testing and test results, and lessons learned.
NASA Astrophysics Data System (ADS)
Franco, J. M.; Gómez, I.
2013-04-01
The construction of high-order exponentially fitted Runge-Kutta-Nyström (EFRKN) methods of explicit type for the numerical solution of oscillatory differential systems is analyzed. Based on two basic symmetric and symplectic EFRKN methods of reference we present two procedures for constructing high-order explicit methods. The first procedure is based on composition methods and it allows the construction of high-order explicit EFRKN methods which are symmetric and symplectic. The second procedure is based on combining different EFRKN methods in order to construct embedded pairs of explicit parallel EFRKN methods which can be implemented in variable-step codes without additional cost. The numerical experiments carried out show the qualitative behavior and the efficiency of the new EFRKN methods when they are compared with some standard methods proposed in the scientific literature for solving second-order nonstiff differential systems. Catalogue identifier: AEOO_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEOO_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: GNU General Public License No. of lines in distributed program, including test data, etc.: 2527 No. of bytes in distributed program, including test data, etc.: 107433 Distribution format: tar.gz Programming language: Fortran 77. Computer: Standard PC. Operating system: Windows. It might work with others. Successfully tested by CPC on Linux. RAM: For the test problems used less than 1 MB. Classification: 4.3, 4.12, 16.3, 17.17. Nature of problem: Some models in astronomy and astrophysics, quantum mechanics and nuclear physics lead to second-order oscillatory differential systems. The solution of these oscillatory models requires accurate and efficient numerical methods. The codes SVI-IIEXPOreferee.for and SVI-IIvarreferee.for were developed for this purpose. Solution method: We propose high-order exponentially fitted Runge
NASA Astrophysics Data System (ADS)
Dam, Jacobus Adrianus Maria; Pieterman, Karel
The design and construction of three superconducting magnet systems for applications in the fields of medical imaging, plasma physics and nuclear physics are described. All three systems have vacuum impregnated, intrinsically stable coils with cooling at the outer surfaces of the winding package with liquid helium, and are all coupled in some way to closed cycle cooling systems. General theories are discussed. The techniques used in both the design and the construction of the different magnet systems, are given. The use of numerical methods for the calculation of thermal and mechanical properties of superconducting coil systems, is emphasized. The experimental results obtained with the Delft magnetic resonance imaging system are described and examples of images showing sagittal sections of the human head, successfully produced with this system, are given.
Construction of solar-wind-like magnetic fields.
Roberts, D Aaron
2012-12-07
Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfvén waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This Letter provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations; the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the "random" character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes ("discontinuities"), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.
Construction of Solar-Wind-Like Magnetic Fields
NASA Technical Reports Server (NTRS)
Roberts, Dana Aaron
2012-01-01
Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfven waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This paper provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the\\random character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes (discontinuities), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.
Construction of a 3He magnetic force microscope with a vector magnet
NASA Astrophysics Data System (ADS)
Yang, Jinho; Yang, Ilkyu; Kim, Yun Won; Shin, Dongwoo; Jeong, Juyoung; Wulferding, Dirk; Yeom, Han Woong; Kim, Jeehoon
2016-02-01
We constructed a 3He magnetic force microscope operating at the base temperature of 300 mK under a vector magnetic field of 2-2-9 T in the x-y-z direction. Fiber optic interferometry as a detection scheme is employed in which two home-built fiber walkers are used for the alignment between the cantilever and the optical fiber. The noise level of the laser interferometer is close to its thermodynamic limit. The capabilities of the sub-Kelvin and vector field are demonstrated by imaging the coexistence of magnetism and superconductivity in a ferromagnetic superconductor (ErNi2B2C) at T = 500 mK and by probing a dipole shape of a single Abrikosov vortex with an in-plane tip magnetization.
Xiong, Gang; Qin, Xiang-Yang; Shi, Peng-Fei; Hou, Yin-Ling; Cui, Jian-Zhong; Zhao, Bin
2014-04-25
Two unique heptanuclear clusters Ln@Zn6 (Ln = Dy (1), Er (2)) were structurally and magnetically characterized. Each Dy(3+)/Er(3+) is located in a nona-coordinate D(3h) coordination environment, and is encapsulated in a diamagnetic Zn6 cage. Compound 1 exhibits single-ion magnetic behavior, and is the first example of a single-ion magnet (SIM) constructed through embedding one magnetic anisotropic metal ion into a diamagnetic cage.
Dovetail Rotor Construction For Permanent-Magnet Motors
NASA Technical Reports Server (NTRS)
Kintz, Lawrence J., Jr.; Puskas, William J.
1988-01-01
New way of mounting magnets in permanent-magnet, electronically commutated, brushless dc motors. Magnets wedge shaped, tapering toward center of rotor. Oppositely tapered pole pieces, electron-beam welded to rotor hub, retain magnets against centrifugal force generated by spinning rotor. To avoid excessively long electron-beam welds, pole pieces assembled in segments rather than single long bars.
NASA Technical Reports Server (NTRS)
Allen, Gary G.; Alexander, David
1999-01-01
A method is presented for constructing the coronal magnetic field from photospheric magnetograms and observed coronal loops. A set of magnetic field lines generated from magnetogram data is parameterized and then deformed by varying the parameterized values. The coronal flux tubes associated with this field are adjusted until the correlation between the field lines and the observed coronal loops is maximized. A mathematical formulation is described which ensures that (1) the normal component of the photospheric field remains unchanged, (2) the field is given in the entire corona over an active region, (3) the field remains divergence-free, and 4electric currents are introduced into the field. It is demonstrated that a parameterization of a potential field, comprising a radial stretching of the field, can provide a match for a simple bipolar active region, AR 7999, which crossed the central meridian on 1996 November 26. The result is a non-force-free magnetic field with the Lorentz force being of the order of 10(exp -5.5) g per s(exp 2) resulting from an electric current density of 0.79 micro A per m(exp 2). Calculations show that the plasma beta becomes larger than unity at a strong non-radial currents requires low height of about 0.25 solar radii supporting the non-force-free conclusion. The presence of such strong non-radial currents requires large transverse pressure gradients fo maintain a magnetostatic atmosphere, required by the relatively persistent nature of the coronal structures observed in AR 7999. This scheme is an important tool in generating a magnetic field solution consistent with the coronal flux tube observations and the observed photospheric magnetic field.
Construction of a Magnetic Induction Antenna to Detect Schumann Resonances
NASA Astrophysics Data System (ADS)
Fernald, Trevr; Bowers, Alexis; Cossel, Raquel; McIntyre, Maxwell; Reid, John, , Dr.
2016-03-01
An antenna was designed and built to detect magnetic field changes in the form of Schumann resonances. This was done in hopes of eventually being able to correlate data with sprite occurrence. A square loop was constructed with one meter sides using 2x4s and was wrapped with six hundred turns of 0.2mm thick copper wire. The antenna was tested in a rural location in northern Pennsylvania, chosen for its isolation and expectations of low electrical noise. Detected signals were filtered using a band-pass filter and observed using an oscilloscope. The signal had too much interference to make it possible to see any unmistakably Schumann character, but a Fourier Transform function made it possible to see the contribution of each component frequency to the overall interference. This function revealed possible presence of Schumann character in the signal, indicating mostly 2nd and 3rd mode Schumann frequencies. The fundamental mode may have been observed as well, but was less consistent and pronounced than the other frequencies. The performance of the filter was somewhat questionable and electrical noise was evident, so further experimentation is necessary.
Explicitly covariant dispersion relations and self-induced transparency
NASA Astrophysics Data System (ADS)
Mahajan, S. M.; Asenjo, Felipe A.
2017-02-01
Explicitly covariant dispersion relations for a variety of plasma waves in unmagnetized and magnetized plasmas are derived in a systematic manner from a fully covariant plasma formulation. One needs to invoke relatively little known invariant combinations constructed from the ambient electromagnetic fields and the wave vector to accomplish the program. The implication of this work applied to the self-induced transparency effect is discussed. Some problems arising from the inconsistent use of relativity are pointed out.
CONSTRUCTION AND POWER TEST OF THE EXTRACTION KICKER MAGNET FOR SNS ACCUMULATOR RING.
PAI, C.; HAHN, H.; HSEUH, H.; LEE, Y.; MENG, W.; MI,J.; SANDBERG, J.; TODD, R.; ET AL.
2005-05-16
Two extraction kicker magnet assemblies that contain seven individual pulsed magnet modules each will kick the proton beam vertically out of the SNS accumulator ring into the aperture of the extraction Lambertson septum magnet. The proton beam then travels to the 1.4 MW SNS target assembly. The 14 kicker magnets and major components of the kicker assembly have been fabricated in BNL. The inner surfaces of the kicker magnets were coated with TiN to reduce the secondary electron yield. All 14 PFN power supplies have been built, tested and delivered to OWL. Before final installation, a partial assembly of the kicker system with three kicker magnets was assembled to test the functions of each critical component in the system. In this paper we report the progress of the construction of the kicker components, the TIN coating of the magnets, the installation procedure of the magnets and the full power test of the kicker with the PFN power supply.
Construction of Superconducting Magnet System for the J-PARC Neutrino Beam Line
Nakamoto, T.; Wanderer, P.; Sasaki, K.; Ajima, Y.; Araoka, O.; Fujii, Y.; Hastings, N.; Higashi, N.; Iida, M.; Ishii, T.; Kimura, N.; Kobayashi, T.; Makida, Y.; Nakadaira, T.; Ogitsu, T.; Ohhata, H.; Okamura, T.; Sakashita, K.; Sugawara, S.; Suzuki, S.; Tanaka, K.; Tomaru, T.; Terashima, A.; Yamamoto, A.; Ichikawa, A.; Kakuno, H.; Anerella, M.; Escallier, J.; Ganetis, G.; gupta, R.; Jain, A.; Muratore, J.; Parker, B.; Boussuge, T.; Charrier, J.-P.; Arakawa, M.; Ichihara, T.; Minato, T.; Okada, Y.; Itou, A.; Kumaki, T.; Nagami, M.; Takahashi, T.
2009-10-18
Following success of a prototype R&D, construction of a superconducting magnet system for J-PARC neutrino beam line has been carried out since 2005. A new conceptual beam line with the superconducting combined function magnets demonstrated the successful beam transport to the neutrino production target.
Sources of Constructive Social Relationships in an Urban Magnet School.
ERIC Educational Resources Information Center
Metz, Mary Haywood
1983-01-01
In an urban magnet middle school serving mostly minority, poor, and low achieving students, the presence of high levels of interracial interaction and positive student-teacher relationships was attributed to the school's curricular, academic reward, and classroom activity structures, and to a faculty subculture that encouraged teachers to foster…
NASA Astrophysics Data System (ADS)
Saisut, J.; Kusoljariyakul, K.; Rimjaem, S.; Kangrang, N.; Wichaisirimongkol, P.; Thamboon, P.; Rhodes, M. W.; Thongbai, C.
2011-05-01
The Plasma and Beam Physics Research Facility at Chiang Mai University has established a THz facility to focus on the study of ultra-short electron pulses. Short electron bunches can be generated from a system that consists of a radio-frequency (RF) gun with a thermionic cathode, an alpha magnet as a magnetic bunch compressor, and a linear accelerator as a post-acceleration section. The alpha magnet is a conventional and simple instrument for low-energy electron bunch compression. With the alpha magnet constructed in-house, several hundred femtosecond electron bunches for THz radiation production can be generated from the thermionic RF gun. The construction and performance of the alpha magnet, as well as some experimental results, are presented in this paper.
Magnetic Probe Construction using Thick-film Technology
Takahashi, H.; Sakakibara, S.; Kubota, Y.; and Yamada, H.
2001-02-02
Thick-film technology has been successfully adapted for the design and fabrication of magnetic probes of a new type suitable for use in the simultaneous ultra-high vacuum and high-temperature environment of a nuclear fusion device. The maximum usable temperature is expected to be around 900 degrees C. This new probe has a specific sensitivity (coupling area per unit volume) an order of magnitude higher than a conventional coil. The new probe in one implementation is capable of simultaneously measuring magnetic field in three orthogonal directions about a single spatial point and in two frequency ranges. Low-frequency coils have a measured coupling area of 296-323 cm squared and a frequency response of about 300 kHz. High-frequency coils have a design coupling area of 12-15 cm squared.
Allaire, P; Hilton, E; Baloh, M; Maslen, E; Bearnson, G; Noh, D; Khanwilkar, P; Olsen, D
1998-06-01
A new centrifugal continuous flow ventricular assist device, the CFVAD III, which is fully magnetic bearing suspended, has been developed. It has only one moving part (the impeller), has no contact (magnetic suspension), is compact, and has minimal heating. A centrifugal impeller of 2 inch outer diameter is driven by a permanent magnet brushless DC motor. This paper discusses the design, construction, testing, and performance of the magnetic bearings in the unit. The magnetic suspension consists of an inlet side magnetic bearing and an outlet side magnetic bearing, each divided into 8 pole segments to control axial and radial displacements as well as angular displacements. The magnetic actuators are composed of several different materials to minimize size and weight while having sufficient load capacity to support the forces on the impeller. Flux levels in the range of 0.1 T are employed in the magnetic bearings. Self sensing electronic circuits (without physical sensors) are employed to determine the impellar position and provide the feedback control signal needed for the magnetic bearing control loops. The sensors provide position sensitivity of approximately 0.025 mm. A decentralized 5 axis controller has been developed using modal control techniques. Proportional integral derivative controls are used for each axis to levitate the magnetically supported impeller.
Penland, Nisa; Choi, Eunpyo; Perla, Mikael; Park, Jungyul; Kim, Deok-Ho
2017-02-17
We report a simple and versatile method for in vitro fabrication of scaffold-free tissue-engineered constructs with predetermined cellular alignment, by combining magnetic cell levitation with thermoresponsive nanofabricated substratum (TNFS) based cell sheet engineering technique. The TNFS based nanotopography provides contact guidance cues for regulation of cellular alignment and enables cell sheet transfer, while magnetic nanoparticles facilitate the magnetic levitation of the cell sheet. The temperature-mediated change in surface wettability of the thermoresponsive poly(N-isopropylacrylamide), substratum enables the spontaneous detachment of cell monolayers, which can then be easily manipulated through use of a ring or disk shaped magnet. Our developed platform could be readily applicable to production of tissue-engineered constructs containing complex physiological structures for the study of tissue structure-function relationships, drug screening, and regenerative medicine.
NASA Astrophysics Data System (ADS)
Penland, Nisa; Choi, Eunpyo; Perla, Mikael; Park, Jungyul; Kim, Deok-Ho
2017-02-01
We report a simple and versatile method for in vitro fabrication of scaffold-free tissue-engineered constructs with predetermined cellular alignment, by combining magnetic cell levitation with thermoresponsive nanofabricated substratum (TNFS) based cell sheet engineering technique. The TNFS based nanotopography provides contact guidance cues for regulation of cellular alignment and enables cell sheet transfer, while magnetic nanoparticles facilitate the magnetic levitation of the cell sheet. The temperature-mediated change in surface wettability of the thermoresponsive poly(N-isopropylacrylamide), substratum enables the spontaneous detachment of cell monolayers, which can then be easily manipulated through use of a ring or disk shaped magnet. Our developed platform could be readily applicable to production of tissue-engineered constructs containing complex physiological structures for the study of tissue structure-function relationships, drug screening, and regenerative medicine.
NASA Technical Reports Server (NTRS)
Gary, G. A.
1998-01-01
The reconstruction of the coronal magnetic field is carried out using a perturbation procedure. A set of magnetic field lines generated from magnetogram data is parameterized and then deformed by varying the parameterized values. The coronal fluxtubes associated with this field are adjusted until the correlation between the field lines and the observed coronal loops is maximized. A mathematical formulation is described which ensures (1) that the normal component of the photospheric field remains unchanged, (2) that the field is given in the entire corona, (3) that the field remains divergence free, and (4) that electrical currents are introduced into the field. It is demonstrated that a simple radial parameterization of a potential field, comprising a radial stretching of the field, can provide a match for a simple bipolar active region, AR 7999, which crossed the central meridian on 1996 Nov 26. At a coronal height of 30 km, the resulting magnetic field is a non-force free magnetic field with the maximum Lorentz force being on the order of 2.6 x 10(exp -9) dyn resulting from an electric current density of $0.13 mu A/ sq m. This scheme is an important tool in generating a magnetic field solution consistent with the coronal flux tube observations and the observed photospheric magnetic field.
Design and Construction of a High-Speed Magnetic Tape Duplicator.
ERIC Educational Resources Information Center
Hoskin, Richard K.
Engineering procedures used in the design and construction of a high-speed, multichannel magnetic tape duplicator are described. The completed duplicator, a common mandrel duplicator, in which a single drive motor turns a common capstan shaft at high speeds and moves both master and copy tapes simultaneously, performs satisfactorily yet suggests…
Hirano, Masato; Kubota, Shinji; Koizume, Yoshiki; Tanaka, Shinya; Funase, Kozo
2017-01-01
Motor training induces plastic changes in the primary motor cortex (M1). However, it is unclear whether and how the latency of motor-evoked potentials (MEP) and MEP amplitude are affected by implicit and/or explicit motor learning. Here, we investigated the changes in M1 excitability and MEP latency induced by implicit and explicit motor learning. The subjects performed a serial reaction time task (SRTT) with their five fingers. In this task, visual cues were lit up sequentially along with a predetermined order. Through training, the subjects learned the order of sequence implicitly and explicitly. Before and after the SRTT, we recorded MEP at 25 stimulation points around the hot spot for the flexor pollicis brevis (FPB) muscle. Although no changes in MEP amplitude were observed in either session, we found increases in MEP latency and changes in histogram of MEP latency after implicit learning. Our results suggest that reorganization across the motor cortices occurs during the acquisition of implicit knowledge. In contrast, acquisition of explicit knowledge does not appear to induce the reorganization based on the measures we recorded. The fact that the above mentioned increases in MEP latency occurred without any alterations in MEP amplitude suggests that learning has different effects on different physiological signals. In conclusion, our results propose that analyzing a combination of some indices of M1 excitability, such as MEP amplitude and MEP latency, is encouraged in order to understand plasticity across motor cortices. PMID:28101014
Hirano, Masato; Kubota, Shinji; Koizume, Yoshiki; Tanaka, Shinya; Funase, Kozo
2016-01-01
Motor training induces plastic changes in the primary motor cortex (M1). However, it is unclear whether and how the latency of motor-evoked potentials (MEP) and MEP amplitude are affected by implicit and/or explicit motor learning. Here, we investigated the changes in M1 excitability and MEP latency induced by implicit and explicit motor learning. The subjects performed a serial reaction time task (SRTT) with their five fingers. In this task, visual cues were lit up sequentially along with a predetermined order. Through training, the subjects learned the order of sequence implicitly and explicitly. Before and after the SRTT, we recorded MEP at 25 stimulation points around the hot spot for the flexor pollicis brevis (FPB) muscle. Although no changes in MEP amplitude were observed in either session, we found increases in MEP latency and changes in histogram of MEP latency after implicit learning. Our results suggest that reorganization across the motor cortices occurs during the acquisition of implicit knowledge. In contrast, acquisition of explicit knowledge does not appear to induce the reorganization based on the measures we recorded. The fact that the above mentioned increases in MEP latency occurred without any alterations in MEP amplitude suggests that learning has different effects on different physiological signals. In conclusion, our results propose that analyzing a combination of some indices of M1 excitability, such as MEP amplitude and MEP latency, is encouraged in order to understand plasticity across motor cortices.
Construction of a high-performance magnetic enzyme nanosystem for rapid tryptic digestion
NASA Astrophysics Data System (ADS)
Cheng, Gong; Zheng, Si-Yang
2014-11-01
A magnetic enzyme nanosystem have been designed and constructed by a polydopamine (PDA)-modification strategy. The magnetic enzyme nanosystem has well defined core-shell structure and a relatively high saturation magnetization (Ms) value of 48.3 emu g-1. The magnetic enzyme system can realize rapid, efficient and reusable tryptic digestion of proteins by taking advantage of its magnetic core and biofunctional shell. Various standard proteins (e.g. cytochrome C (Cyt-C), myoglobin (MYO) and bovine serum albumin (BSA)) have been used to evaluate the effectiveness of the magnetic enzyme nanosystem. The results show that the magnetic enzyme nanosystem can digest the proteins in 30 minutes, and the results are comparable to conventional 12 hours in-solution digestion. Furthermore, the magnetic enzyme nanosystem is also effective in the digestion of low-concentration proteins, even at as low as 5 ng μL-1 substrate concentration. Importantly, the system can be reused several times, and has excellent stability for storage. Therefore, this work will be highly beneficial for the rapid digestion and identification of proteins in future proteomics.
NASA Astrophysics Data System (ADS)
Bayne, Michael G.; Uchida, Yuki; Eller, Joshua; Daniels, Carena; Chakraborty, Arindam
2016-11-01
The computational cost of performing a configuration interaction (CI) calculation for treating electron-electron correlation is directly proportional to the number of terms in the CI expansion. In this work, we present a diagrammatic projection approach for a priori identification of noncontributing terms in a CI expansion. This method known as the geminal-projected configuration interaction (GP-CI) method is based on using a two-body R12 geminal operator for describing electron-electron correlation in a reference many-electron wave function. The diagrammatic projection procedure was performed by first deriving the Hugenholtz diagrams of the energy expression of the R12 reference wave function and then performing diagrammatic factorization of effective particle-hole creation operators. The projection operation, which is a functional of the geminal function, was defined and used for the construction of the geminal-projected particle-hole creation operators. The form of the two-body R12 geminal operator was derived analytically by imposing an approximate Kato cusp condition. A linear combination of the geminal-projected one-particle one-hole and two-particle two-hole operators were used for the construction of the GP-CI wave function. The applicability and implementation of the diagrammatic projection method was demonstrated by performing proof-of-concept calculations on an isoelectronic series of 10 electron systems: CH4,NH3,H2O ,HF , and Ne . The results from the calculations show that compared to conventional CI calculations, the GP-CI method was able to substantially reduce the size of the CI space (by a factor of 6-9) while maintaining an accuracy of 10-5 Hartrees for the ground-state energies. These results demonstrate the ability of the diagrammatic projection procedure to identify noncontributing states using an analytical form of the R12 geminal correlator operator. The geminal-projection method was also applied to second-order Møller-Plesset perturbation
Yao, Quanfu; Gao, Yangyang; Gao, Tianyi; Zhang, Yanling; Harnoode, Chokto; Dong, Alideertu; Liu, Ying; Xiao, Linghan
2016-08-01
Magnetic recyclable antibacterial nanomaterials, i.e., magnetic amine N-halamine nanoparticles (Fe3O4@SiO2/CTMP NPs), were constructed by arming magnetic silica nanoparticles (Fe3O4@SiO2 NPs) with amine N-halamine (CTMP). Magnetic iron oxide nanoparticles were encapsulated into silica layers followed by anchoring antibacterial amine N-halamines to give magnetic/antibacterial bi-functional agents with core-shell structure. Since the presence of Fe3O4 NPs in core, the products offer super-paramagnetic behavior, which made them separable magnetically after the antibacterial behavior. Their sterilizing effect on bacterial strain was evaluated using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as model bacteria via the plate counting technique, zone of inhibition study, and time kill assay. Antibacterial mechanism study illustrated that the products integrate both the contact mechanism and the release mechanism for attacking bacteria. The significant effect of oxidative chlorine content and concentration of the products on antibiotic action were confirmed. Thanks to the magnetic property, the potential recyclability of the products was achieved. Most significantly, the products retain effective antibacterial action even after five cycles. These findings revealed that the products Fe3O4@SiO2/CTMP NPs have promising applications in the antibacterial fields.
Progress on Design and Construction of a MuCool Coupling Solenoid Magnet
Wang, L.; Liu, Xiao Kun; Xu, FengYu; Li, S.; Pan, Heng; Wu, Hong; Guo, Xinglong; Zheng, ShiXian; Li, Derun; Virostek, Steve; Zisman, Mike; Green, M.A.
2010-06-28
The MuCool program undertaken by the US Neutrino Factory and Muon Collider Collaboration is to study the behavior of muon ionization cooling channel components. A single superconducting coupling solenoid magnet is necessary to pursue the research and development work on the performance of high gradient, large size RF cavities immersed in magnetic field, which is one of the main challenges in the practical realization of ionization cooling of muons. The MuCool coupling magnet is to be built using commercial copper based niobium titanium conductors and cooled by two cryo-coolers with each cooling capacity of 1.5 W at 4.2 K. The solenoid magnet will be powered by using a single 300A power supply through a single pair of binary leads that are designed to carry a maximum current of 210A. The magnet is to be passively protected by cold diodes and resistors across sections of the coil and by quench back from the 6061 Al mandrel in order to lower the quench voltage and the hot spot temperature. The magnet is currently under construction. This paper presents the updated design and fabrication progress on the MuCool coupling magnet.
The Fermilab Main Injector Dipole construction techniques and prototype magnet measurements
Bleadon, M.E.; Brown, B.C.; Chester, N.S.; Desavouret, E.; Garvey, J.D.; Glass, H.D.; Harding, D.J.; Harfoush, F.A.; Holmes, S.D.; Humbert, J.C. )
1992-01-01
The Fermilab Main Injector Project will provide 120-150 GeV Proton and Antiproton Beams for Fermilab Fixed Target Physics and Colliding Beams Physics use. A dipole magnet has been designed and prototypes constructed for the principal bending magnets of this new accelerator. In this paper the design considerations and fabrication techniques are described. Measurement results on prototypes are reported, emphasizing the field uniformity achieved in both body field and end field at excitation levels from injection at 0.1 T to full field of 1.7 T.
The Fermilab main injector dipole construction techniques and prototype magnet measurements
Bleadon, M.; Brown, B.; Chester, N.; Desavouret, E.; Garvey, J.; Glass, H.; Harding, D.; Harfoush, F.; Holmes, S.; Humbert, J.; Kerby, J.; Knauf, A.; Kobliska, G.; Lipski, A.; Martin, P.; Mazur, P.; Orris, D.; Ostiguy, J.; Peggs, S.; Pachnik, J.; Pewitt, E.; Satti, J.; Schmidt, E.; Sim, J.; Snowdon, S.; Walbridge, D.
1991-09-01
The Fermilab Main Injector Project will provide 120--150 GeV Proton and Antiproton Beams for Fermilab Fixed Target Physics and Colliding Beams Physics use. A dipole magnet has been designed and prototypes constructed for the principal bending magnets of this new accelerator. The design considerations and fabrication techniques are described. Measurement results on prototypes are reported, emphasizing the field uniformity achieved in both body field and end field at excitation levels from injection at 0.1 T to full field of 1.7 T. 6 refs., 5 figs., 3 tabs.
NASA Astrophysics Data System (ADS)
Nishiyama, N.; Tanimoto, K.; Makino, A.
2016-05-01
Recently updated nanocrystalline soft magnetic Fe-Co-Si-B-P-Cu alloys "NANOMET®" exhibit high saturation magnetic flux density (Bs > 1.8 T), low coercivity (Hc < 10 A/m) and low core loss (W1.7/50 ˜ 0.4 W/kg) even in a ribbon form with a thickness of up to 40 μm. By utilize excellent magnetic softness, several products such as motors or transformers for electrical appliances are now under developing by industry-academia collaboration. In particular, it is found that a brushless DC motor using NANOMET® core exhibited remarkable improvement in energy consumption. The prototype motor with an outer core diameter of 70 mm and a core thickness of 50 mm was constructed using laminated nano-crystallized NANOMET® ribbons. Core-loss for the constructed motor was improved from 1.4 W to 0.4 W only by replacing the non-oriented Si-steel core with NANOMET® one. The overall motor efficiency is evaluated to be 3% improvement. In this work, the relation between processing and resulting magnetic properties will be presented. In addition, feasibility for commercialization will also be discussed.
Wani, Nisar A.; Jehangir, Majid; Lone, Parveen A.
2017-01-01
Purpose: To highlight the role of constructive interference steady state (CISS) magnetic resonance imaging (MRI) in the diagnosis of Tolosa-Hunt Syndrome (THS). Case Report: We describe a case of THS in a 55-year-old woman presenting with left painful opthalmoplegia that was diagnosed by CISS MRI. Patient responded to steroid treatment and the lesion resolved. Conclusion: Imaging with MRI can help in making the diagnosis of THS by demonstrating an enhancing soft tissue lesion in the cavernous sinus and orbital apex resolving with steroids. CISS MRI is a sensitive sequence for diagnosis and follow-up imaging in THS. PMID:28299013
Construction of van der Waals magnetic tunnel junction using ferromagnetic layered dichalcogenide
NASA Astrophysics Data System (ADS)
Arai, Miho; Moriya, Rai; Yabuki, Naoto; Masubuchi, Satoru; Ueno, Keiji; Machida, Tomoki
2015-09-01
We investigate the micromechanical exfoliation and van der Waals (vdW) assembly of ferromagnetic layered dichalcogenide Fe0.25TaS2. The vdW interlayer coupling at the Fe-intercalated plane of Fe0.25TaS2 allows exfoliation of flakes. A vdW junction between the cleaved crystal surfaces is constructed by dry transfer method. We observe tunnel magnetoresistance in the resulting junction under an external magnetic field applied perpendicular to the plane, demonstrating spin-polarized tunneling between the ferromagnetic layered material and the vdW junction.
Design and construction of a magnetic resonance compatible multi-injector gas jet delivery system
NASA Astrophysics Data System (ADS)
Megias-Alguacil, David; Keller, Thierry; Lutz, Kai; Barlow, Ashley P.; Ettlin, Dominik A.
2008-01-01
We present the design, construction, and performance of a novel multi-injector gas jet delivery capable of operating in a magnetic resonance imaging environment. This apparatus is computer controlled and built with two separate pneumatic circuits enabling gas jet applications at variable sites through four independently activated injectors. Gas jet delivery is fully controllable in terms of pressure, flow rate, gas temperature, application time, and duration of interstimulus interval. We characterized these parameters, considering effects such as pressure drop by flow transport, transient effects, and delays in activation. The system offers new possibilities for use in various biomedical contexts such as, e.g., quantitative sensory testing or dental hypersensitivity assessment.
Construction of Bending Magnet Beamline at the APS for Environmental Studies
E. A. Stern
1999-09-14
The objective of this research was to design and construct a bending magnet beamline at the Advanced Photon Source. The beamline is to be optimized for x-ray absorption spectroscopy (XAS) studies with a major focus on environmental issues. The beamline will share the experimental facilities under development at the neighboring undulator-based insertion device beamline. It will utilize these facilities for XAS of both bulk and surface samples, with spatial and elemental imaging, on toxic and radioactive samples. It will help meet the rapidly growing need for the application of these techniques to environmental problems.
Construction of van der Waals magnetic tunnel junction using ferromagnetic layered dichalcogenide
Arai, Miho; Moriya, Rai Yabuki, Naoto; Masubuchi, Satoru; Ueno, Keiji; Machida, Tomoki
2015-09-07
We investigate the micromechanical exfoliation and van der Waals (vdW) assembly of ferromagnetic layered dichalcogenide Fe{sub 0.25}TaS{sub 2}. The vdW interlayer coupling at the Fe-intercalated plane of Fe{sub 0.25}TaS{sub 2} allows exfoliation of flakes. A vdW junction between the cleaved crystal surfaces is constructed by dry transfer method. We observe tunnel magnetoresistance in the resulting junction under an external magnetic field applied perpendicular to the plane, demonstrating spin-polarized tunneling between the ferromagnetic layered material and the vdW junction.
Explicit high-order symplectic integrators for charged particles in general electromagnetic fields
NASA Astrophysics Data System (ADS)
Tao, Molei
2016-12-01
This article considers non-relativistic charged particle dynamics in both static and non-static electromagnetic fields, which are governed by nonseparable, possibly time-dependent Hamiltonians. For the first time, explicit symplectic integrators of arbitrary high-orders are constructed for accurate and efficient simulations of such mechanical systems. Performances superior to the standard non-symplectic method of Runge-Kutta are demonstrated on two examples: the first is on the confined motion of a particle in a static toroidal magnetic field used in tokamak; the second is on how time-periodic perturbations to a magnetic field inject energy into a particle via parametric resonance at a specific frequency.
Ab initio construction of magnetic phase diagrams in alloys: The case of Fe1-xMnxPt
Pujari, B. S.; Larson, P.; Antropov, V. P.; ...
2015-07-28
A first-principles approach to the construction of concentration-temperature magnetic phase diagrams of metallic alloys is presented. The method employs self-consistent total energy calculations based on the coherent potential approximation for partially ordered and noncollinear magnetic states and is able to account for competing interactions and multiple magnetic phases. The application to the Fe1–xMnxPt “magnetic chameleon” system yields the sequence of magnetic phases at T = 0 and the c-T magnetic phase diagram in good agreement with experiment, and a new low-temperature phase is predicted at the Mn-rich end. The importance of non-Heisenberg interactions for the description of the magnetic phasemore » diagram is demonstrated.« less
Pupil Dilation to Explicit and Non-Explicit Sexual Stimuli.
Watts, Tuesday M; Holmes, Luke; Savin-Williams, Ritch C; Rieger, Gerulf
2017-01-01
Pupil dilation to explicit sexual stimuli (footage of naked and aroused men or women) can elicit sex and sexual orientation differences in sexual response. If similar patterns were replicated with non-explicit sexual stimuli (footage of dressed men and women), then pupil dilation could be indicative of automatic sexual response in fully noninvasive designs. We examined this in 325 men and women with varied sexual orientations to determine whether dilation patterns to non-explicit sexual stimuli resembled those to explicit sexual stimuli depicting the same sex or other sex. Sexual orientation differences in pupil dilation to non-explicit sexual stimuli mirrored those to explicit sexual stimuli. However, the relationship of dilation to non-explicit sexual stimuli with dilation to corresponding explicit sexual stimuli was modest, and effect magnitudes were smaller with non-explicit sexual stimuli than explicit sexual stimuli. The prediction that sexual orientation differences in pupil dilation are larger in men than in women was confirmed with explicit sexual stimuli but not with non-explicit sexual stimuli.
SCR-1: Design and Construction of a Small Modular Stellarator for Magnetic Confinement of Plasma
NASA Astrophysics Data System (ADS)
Barillas, L.; Vargas, V. I.; Alpizar, A.; Asenjo, J.; Carranza, J. M.; Cerdas, F.; Gutiérrez, R.; Monge, J. I.; Mora, J.; Morera, J.; Peraza, H.; Queral, V.; Rojas, C.; Rozen, D.; Saenz, F.; Sánchez, G.; Sandoval, M.; Trimiño, H.; Umaña, J.; Villegas, L. F.
2014-05-01
This paper describes briefly the design and construction of a small modular stellarator for magnetic confinement of plasma, called Stellarator of Costa Rica 1, or SCR-1; developed by the Plasma Physics Group of the Instituto Tecnológico de Costa Rica, PlasmaTEC. The SCR-1 is based on the small Spanish stellarator UST_1, created by the engineer Vicente Queral. The SCR-1 will employ stainless steel torus-shaped vacuum vessel with a major radius of 460.33 mm and a cross section radius of 110.25mm. A typical SCR-1 plasma will have an average radius 42.2 mm and a volume of 8 liters (0.01 m3), and an aspect ratio of 5.7. The magnetic resonant field will be 0.0878 T, and a period of 2 (m=2) with a rotational transform of 0.3. The magnetic field will be provided by 12 modular coils, with 8 turns each, with an electrical current of 8704 A per coil (1088 A per turn of each coil). This current will be fed by a bank of cell batteries. The plasma will be heated by ECRH with magnetrons of a total power of 5kW, in the first harmonic at 2.45GHz. The expected electron temperature and density are 15 eV and 1017 m-3 respectively with an estimated confinement time of 7.30 x 10-4 ms. The initial diagnostics on the SCR-1 will consist of a Langmuir probe, a heterodyne microwave interferometer, and a field mapping system. The first plasma of the SCR-1 is expected at the end of 2011.
2002-01-01
Harbor Deepening Project, Jacksonville, FL Palm Valley Bridge Project, Jacksonville, FL Rotary Club of San Juan, San Juan, PR Tren Urbano Subway...David. What is nanotechnology? What are its implications for construction?, Foresight/CRISP Workshop on Nanotechnology, Royal Society of Arts
2002-01-01
San Juan, PR Tren Urbano Subway Project, San Juan, PR U.S. Army South, San Juan, PR U.S. Coast Guard Housing Project, San Juan, PR U.S. Coast Guard...construction?, Foresight/CRISP Workshop on Nanotechnology, Royal Society of Arts . Cheltenham, England: 2001, p.5. 56 Concrete Proposals, Economist, July 24
Effects of Explicit Instructions, Metacognition, and Motivation on Creative Performance
ERIC Educational Resources Information Center
Hong, Eunsook; O'Neil, Harold F.; Peng, Yun
2016-01-01
Effects of explicit instructions, metacognition, and intrinsic motivation on creative homework performance were examined in 303 Chinese 10th-grade students. Models that represent hypothesized relations among these constructs and trait covariates were tested using structural equation modelling. Explicit instructions geared to originality were…
NASA Astrophysics Data System (ADS)
Makida, Y.; Ohhata, H.; Okamura, T.; Suzuki, S.; Araoka, O.; Ogitsu, T.; Kimura, N.; Nakamoto, T.; Sasaki, K.; Kaneda, S.; Takahashi, T.; Ito, A.; Nagami, M.; Kumaki, T.; Nakashima, T.
2010-04-01
A helium cryogenic plant has been constructed in the proton accelerator research complex, J-PARC, to cool a string of superconducting magnets in the neutrino beam line since 2005. It consists of a screw compressor with a capacity of 160 g/s at 1.4 MPa, a 1.5 kW refrigerator, a centrifugal SHE pump with a flow rate of 300 g/s and peripherals. After system integration, performance tests have been carried out. In a preliminary cooling test without magnets, the cryogenic system attained a cooling capacity of 522 W by circulating supercritical helium flow of 300 g/s at 0.4 MPa and at 4.5 K. Afterwards a full system test with the magnets was carried out. The magnets were successfully charged up to an ultimate current of 5000 A beyond a nominal current of 4400 A. This paper describes the plant design and the result of performance measurements.
Segmentation of magnetic resonance images to construct human head model for diffuse optical imaging
NASA Astrophysics Data System (ADS)
Kurihara, Kazuki; Kawaguchi, Hiroshi; Takahashi, Yosuke; Obata, Takayuki; Okada, Eiji
2011-07-01
The brain activation image obtained by diffuse optical tomography (DOT) is obtained by solving inverse problem using the spatial sensitivity profile (SSP). The SSP can be obtained from the analysis of the light propagation using threedimensional head models. The head model is based upon segmented magnetic resonance (MR) image and there are several types of software based on binarization for segmentation of MR head images. We segmented superficial tissues which effect the light propagation in human head from MR images acquired with FATSAT and FIESTA pulse sequences by using region growing algorithm and morphological operation to facilitate the construction of the individual head models for DOT. The pixel intensity distribution of these images has appropriate characteristics to extract the superficial tissues by using algorithm based on binarization. The result of extraction was compared with the extraction from T2-weighted image which is commonly used to extract superficial tissues. The result of extraction from FATSAT or FIESTA image agree well with ground truth determined by manual segmentation.
What Should Be Explicit in Explicit Grammar Instruction?
ERIC Educational Resources Information Center
Nagai, Noriko; Ayano, Seiki; Okada, Keiko; Nakanishi, Takayuki
2015-01-01
This article proposes an approach to explicit grammar instruction that seeks to develop metalinguistic knowledge of the L2 and raise L2 learners' awareness of their L1, which is crucial for the success of second language acquisition (Ellis 1997, 2002). If explicit instruction is more effective than implicit instruction (Norris and Ortega 2000),…
Huang, Chi-Fang; Lin, Xi-Zhang; Lo, Wei-Hung
2010-01-01
For the applications of localized hyperthermia, an improved magnetic induction-heating system is described. The associated components of this system, for example, coils for generating magnetic field, magnetic circuit for flux path, and ferrite needles for generating heat by magnetic induction, all have been explained. An animal experiment of induction-heating hyperthermia for rat's liver is also carried out, and the consequent pathology of Hematoxylin and Eosin (H&E) stain and NADPH oxidase activity assay are also conducted for evaluation.
The Explicit Teaching of Reading.
ERIC Educational Resources Information Center
Hancock, Joelie, Ed.
Exploring the explicit teaching of reading, this book is the result of a group of Australian teachers who took a closer look at their teaching so that they could be clearer to their kindergarten through middle-school students. Chapter 1 is based on a presentation at a Saturday inservice program on explicit teaching. Chapters 2-9 were written by…
Explicit Substitutions and All That
NASA Technical Reports Server (NTRS)
Ayala-Rincon, Mauricio; Munoz, Cesar; Busnell, Dennis M. (Technical Monitor)
2000-01-01
Explicit substitution calculi are extensions of the Lambda-calculus where the substitution mechanism is internalized into the theory. This feature makes them suitable for implementation and theoretical study of logic-based tools such as strongly typed programming languages and proof assistant systems. In this paper we explore new developments on two of the most successful styles of explicit substitution calculi: the lambda(sigma)- and lambda(s(e))-calculi.
Explicit Substitutions and All That
NASA Technical Reports Server (NTRS)
Ayala-Rincon, Mauricio; Munoz, Cesar
2000-01-01
Explicit substitution calculi are extensions of the lambda-calculus where the substitution mechanism is internalized into the theory. This feature makes them suitable for implementation and theoretical study of logic-based tools such as strongly typed programming languages and proof assistant systems. In this paper we explore new developments on two of the most successful styles of explicit substitution calculi: the lambda sigma- and lambda S(e)-calculi.
Explicit field realizations of W algebras
NASA Astrophysics Data System (ADS)
Wei, Shao-Wen; Liu, Yu-Xiao; Zhang, Li-Jie; Ren, Ji-Rong
2009-06-01
The fact that certain nonlinear W2,s algebras can be linearized by the inclusion of a spin-1 current can provide a simple way to realize W2,s algebras from linear W1,2,s algebras. In this paper, we first construct the explicit field realizations of linear W1,2,s algebras with double scalar and double spinor, respectively. Then, after a change of basis, the realizations of W2,s algebras are presented. The results show that all these realizations are Romans-type realizations.
Marcouille, O.; Brunelle, P.; Chubar, O.; Marteau, F.; Massal, M.; Nahon, L.; Tavakoli, K.; Veteran, J.; Filhol, J.-M.
2007-01-19
A novel electromagnetic Insertion Device (ID) called HU640 (OPHELIE2) has been developed and constructed for the DESIRS beam line at SOLEIL. It is a 10 m-long helical/planar undulator designed to produce any kind of switchable photon polarizations in the range 5 eV - 40 eV. It is composed of three sets of pure air coils mounted in a special arrangment. One set coils is dedicated to generate the horizontal field component. Two other sets, shifted the one from the other by a quarter of period along the ID axis, produce the vertical component with a continuous translation dephasing varying from -180 deg. to +180 deg. . The use of non magnetic material makes the undulator linear with the coil current in terms of peak field and residual integrated field errors. This allows the number of magnetic controls, corrections to be significantly reduced and to ease the on-beam operation. The paper presents the design, the construction and the magnetic measurements of the undulator.
Xu, Shoujun; Rochester, Simon M.; Yashchuk, Valeriy V.; Donaldson, Marcus H.; Budker, Dmitry
2006-06-28
We report on the design, characterization, and applicationsof a sensitive atomic magnetic gradiometer. The device is based onnonlinear magneto-optical rotation in alkali-metal (87Rb) vapor, and usesfrequency-modulated laser light. The magnetic field produced by a sampleis detected by measuring the frequency of a resonance in optical rotationthat arises when the modulation frequency equals twice the Larmorprecession frequency of the Rb atoms. The gradiometer consists of twoatomic magnetometers. The rotation of light polarization in eachmagnetometer is detected with a balanced polarimeter. The sensitivity ofthe gradiometer is 0.8 nG/Hz1/2 for near-DC (0.1 Hz) magnetic fields,with a baseline of 2.5 cm. For applications in nuclear magnetic resonance(NMR) and magnetic resonance imaging (MRI), a long solenoid that piercesthe magnetic shields provides a ~;0.5 G leading field for the nuclearspins in the sample. Our apparatus is particularly suited for remotedetection of NMR and MRI. We demonstrate a point-by-point free inductiondecay measurement and a spin echo reconstructed with a pulse sequencesimilar to the Carr-Purcell-Meiboom-Gill (CPMG) pulse. Additionalapplications and future improvements are also discussed.
NASA Astrophysics Data System (ADS)
Egorov, Yu. G.; Kulkov, V. M.; Terentyev, V. V.; Firsyuk, S. O.; Shemyakov, A. O.
2016-11-01
The problem of controlling the angular momentum of spacecraft using magnetic attitude control systems interacting with the Earth's magnetic field is considered. A mathematical model for the angular motion dynamics of a spacecraft has been constructed. An approach to determining the parameters of the control law for a spacecraft attitude control and stabilization system that ensures angular momentum dissipation is proposed.
30 MJ superconducting magnetic energy storage stabilizing coil. Final report for construction
1983-03-01
This report covers Phase II, Fabrication and Delivery of the 30 MJ Superconducting Magnetic Energy Storage Stabilizing Coil. A history of the manufacturing and assembly phase of the magnet is presented. Major problems and solutions are summarized, and illustrations of the major operations are provided. The Quality Assurance program is described with a listing of all nonconformance reports. Design documentation is provided, including a Design Document Index, monthly progress reports, and a list of papers given on the project. Appendices to the report contain copies of released and revised design calculations, test reports, assembly procedure, and nonconformance reports and engineering dispositions.
Ab initio construction of magnetic phase diagrams in alloys: The case of Fe_{1-x}Mn_{x}Pt
Pujari, B. S.; Larson, P.; Antropov, V. P.; Belashchenko, K. D.
2015-07-28
A first-principles approach to the construction of concentration-temperature magnetic phase diagrams of metallic alloys is presented. The method employs self-consistent total energy calculations based on the coherent potential approximation for partially ordered and noncollinear magnetic states and is able to account for competing interactions and multiple magnetic phases. The application to the Fe_{1–x}Mn_{x}Pt “magnetic chameleon” system yields the sequence of magnetic phases at T = 0 and the c-T magnetic phase diagram in good agreement with experiment, and a new low-temperature phase is predicted at the Mn-rich end. The importance of non-Heisenberg interactions for the description of the magnetic phase diagram is demonstrated.
Design and Construction of a Prototype Solenoid Coil for MICE Coupling Magnets
Wang, Li; Pan, Heng; Guo, XingLong; Xu, FengYu; Liu, XiaoKun; Wu, Hong; Zheng, ShiXian; Green, Michael A; Li, Derun; Virostek, Steve; Zisman, Michael
2010-06-28
A superconducting coupling solenoid mounted around four conventional RF cavities, which produces up to 2.6 T central magnetic field to keep the muons within the cavities, is to be used for the Muon Ionization Cooling Experiment (MICE). The coupling coil made from copper matrix NbTi conductors is the largest of three types of magnets in MICE both in terms of 1.5 m inner diameter and about 13MJ stored magnetic energy at full operation current of 210A. The stress induced inside the coil assembly during cool down and magnet charging is relatively high. In order to validate the design method and develop the coil winding technique with inside-wound SC splices required for the coupling coil, a prototype coil made from the same conductor and with the same diameter and thickness but only one-fourth long as the coupling coil was designed and fabricated by ICST. The prototype coil was designed to be charged to strain conditions that are equivalent or greater than would be encountered in the coupling coil. This paper presents detailed design of the prototype coil as well as developed coil winding skills. The analyses on stress in the coil assembly and quench process were carried out.
Design and Construction Solutions in the Accurate Realization of NCSX Magnetic Fields
Heitzenroeder, P.; Dudek, Lawrence E.; Brooks, Arthur W.; Viola, Michael E.; Brown, Thomas; Neilson, George H.; Zarnstorff, Michael C.; Rej, Donald; Cole,Michael J.; Freudenberg, Kevin D.; Harris J. H.; McGinnis, Gary
2008-09-29
The National Compact Stellarator Experiment, NCSX, is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in partnership with the Oak Ridge national Laboratory. The goal of NCSX is to provide the understanding necessary to develop an attractive, disruption free, steady state compact stellaratorbased reactor design. This paper describes the recently revised designs of the critical interfaces between the modular coils, the construction solutions developed to meet assembly tolerances, and the recently revised trim coil system that provides the required compensation to correct for the “as built” conditions and to allow flexibility in the disposition of as-built conditions. In May, 2008, the sponsor decided to terminate the NCSX project due to growth in the project’s cost and schedule estimates. However significant technical challenges in design and construction were overcome, greatly reducing the risk in the remaining work to complete the project.
Explicit and Implicit Emotion Regulation: A Dual-Process Framework
Gyurak, Anett; Gross, James J.; Etkin, Amit
2012-01-01
It is widely acknowledged that emotions can be regulated in an astonishing variety of ways. Most research to date has focused on explicit (effortful) forms of emotion regulation. However, there is growing research interest in implicit (automatic) forms of emotion regulation. To organize emerging findings, we present a dual-process framework that integrates explicit and implicit forms of emotion regulation, and argue that both forms of regulation are necessary for well-being. In the first section of this review, we provide a broad overview of the construct of emotion regulation, with an emphasis on explicit and implicit processes. In the second section, we focus on explicit emotion regulation, considering both neural mechanisms that are associated with these processes and their experiential and physiological consequences. In the third section, we turn to several forms of implicit emotion regulation, and integrate the burgeoning literature in this area. We conclude by outlining open questions and areas for future research. PMID:21432682
Yao, Hanchun; Su, Li; Zeng, Man; Cao, Li; Zhao, Weiwei; Chen, Chengqun; Du, Bin; Zhou, Jie
2016-01-01
Carbon dots (CDs) are one of the most highlighted carbon-based materials for biological applications, such as optical imaging nanoprobes, which are used for labeling cells in cancer treatment mainly due to their biocompatibility and unique optical properties. In this study, gadolinium (Gd)-complex-containing CDs were obtained through a one-step microwave method to develop multimodal nanoprobes integrating the advantages of optical and magnetic imaging. The obtained Gd-CDs exhibited highly fluorescent properties with excellent water solubility and biological compatibility. Natural apoferritin (AFn) nanocages, an excellent drug delivery carrier, are hollow in structure, with their pH-dependent, unfolding–refolding process at pH 2.0 and 7.4. The chemotherapeutic drug doxorubicin (DOX) can be highly effective and encapsulated into AFn cavity. A widely used tumor-targeting molecule, folic acid (FA), functionalized the surface of AFn to obtain an active tumor targeting effect on MCF-7 cells and malignant tumors in mice models. In this study, an AFn nanocarrier encapsulating high concentration of DOX labeled with magnetic and fluorescent Gd-CDs probe was developed. Gd-CDs exhibited a unique green photoluminescence and almost no toxicity compared with free GdCl3. Furthermore, Gd-doped CDs significantly increased the circulation time and decreased the toxicity of Gd3+ in in vitro and in vivo magnetic resonance imaging, which demonstrated that the AFn nanocages labeled with Gd-CD compounds could serve as an excellent T1 contrast agent for magnetic resonance imaging. The self-assembling multifunctional Gd-CDs/AFn (DOX)/FA nanoparticles have a great potential for cancer theranostic applications. PMID:27660437
Yao, Hanchun; Su, Li; Zeng, Man; Cao, Li; Zhao, Weiwei; Chen, Chengqun; Du, Bin; Zhou, Jie
Carbon dots (CDs) are one of the most highlighted carbon-based materials for biological applications, such as optical imaging nanoprobes, which are used for labeling cells in cancer treatment mainly due to their biocompatibility and unique optical properties. In this study, gadolinium (Gd)-complex-containing CDs were obtained through a one-step microwave method to develop multimodal nanoprobes integrating the advantages of optical and magnetic imaging. The obtained Gd-CDs exhibited highly fluorescent properties with excellent water solubility and biological compatibility. Natural apoferritin (AFn) nanocages, an excellent drug delivery carrier, are hollow in structure, with their pH-dependent, unfolding-refolding process at pH 2.0 and 7.4. The chemotherapeutic drug doxorubicin (DOX) can be highly effective and encapsulated into AFn cavity. A widely used tumor-targeting molecule, folic acid (FA), functionalized the surface of AFn to obtain an active tumor targeting effect on MCF-7 cells and malignant tumors in mice models. In this study, an AFn nanocarrier encapsulating high concentration of DOX labeled with magnetic and fluorescent Gd-CDs probe was developed. Gd-CDs exhibited a unique green photoluminescence and almost no toxicity compared with free GdCl3. Furthermore, Gd-doped CDs significantly increased the circulation time and decreased the toxicity of Gd(3+) in in vitro and in vivo magnetic resonance imaging, which demonstrated that the AFn nanocages labeled with Gd-CD compounds could serve as an excellent T1 contrast agent for magnetic resonance imaging. The self-assembling multifunctional Gd-CDs/AFn (DOX)/FA nanoparticles have a great potential for cancer theranostic applications.
Design and Construction of Test Coils for the MICE Coupling Solenoid Magnet
Wang, Li; Pan, Heng; Xu, F.Y.; Liu, XioaKun; Chen, AnBin; Li, LanKai; Gou, XingLong; Wu, Hong; Green, Michael; Li, Darun; Strauss, Bruce
2008-08-08
The superconducting coupling solenoid to be applied in the Muon Ionization Cooling Experiment (MICE) is made from copper matrix Nb-Ti conductors with inner radius of 750 mm, length of 285 mm and thickness of 102.5 mm at room temperature. The magnetic field up to 2.6 T at the magnet centerline is to keep the muons within the MICE RF cavities. Its self inductance is around 592 H and its magnet stored energy is about 13 MJ at a full current of 210 A for the worst operation case of the MICE channel. The stress induced inside the coil during cool down and charging is relatively high. Two test coils are to build and test in order to validate the design method and develop the fabrication technique required for the coupling coil winding, one is 350 mm inner diameter and full length same as the coupling coil, and the other is one-quarter length and 1.5 m diameter. The 1.5 m diameter coil will be charged to strain conditions that are greater than would be encountered in the coupling coil. This paper presents detailed design of the test coils as well as developed winding skills. The analyses on stress in coil assemblies, AC loss, and quench process are carried out.
Liu, Zhao-Liang; You, Cai-Lian; Wang, Biao; Lin, Jian-Hong; Hu, Xue-Feng; Shan, Xiu-Ying; Wang, Mei-Shui; Zheng, Hou-Bing; Zhang, Yan-Ding
2016-06-01
The aim of the present study was to construct angiopoietin-2 (Ang2)-small interfering (si)RNA chitosan magnetic nanoparticles and to observe the interference effects of the nanoparticles on the expression of the Ang2 gene in human malignant melanoma cells. Ang2-siRNA chitosan magnetic nanoparticles were constructed and transfected into human malignant melanoma cells in vitro. Red fluorescent protein expression was observed, and the transfection efficiency was analyzed. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to assess the inhibition efficiency of Ang2 gene expression. Ang2-siRNA chitosan magnetic nanoparticles were successfully constructed, and at a mass ratio of plasmid to magnetic chitosan nanoparticles of 1:100, the transfection efficiency into human malignant melanoma cells was the highest of the ratios assessed, reaching 61.17%. RT-qPCR analysis showed that the magnetic chitosan nanoparticles effectively inhibited Ang2 gene expression in cells, and the inhibition efficiency reached 59.56% (P<0.05). Ang2-siRNA chitosan magnetic nanoparticles were successfully constructed. The in vitro studies showed that the nanoparticles inhibited Ang2 gene expression in human malignant melanoma tumor cells, which laid the foundation and provided experimental evidence for additional future in vivo studies of intervention targeting malignant melanoma tumor growth in nude mice.
NASA Technical Reports Server (NTRS)
Fine, K.
1977-01-01
A basic coaxial mass driver has been constructed by a group of students to verify performance predictions in the acceleration range envisaged for the first lunar device. The bucket is guided by four copper tubes which also supply direct current excitation for its single aluminum coil, and is accelerated by twenty coaxial coils along a 2 m track, followed by a deceleration section. The coils are individually energized by electrolytic photoflash capacitors triggered by solid state switches on the basis of bucket position.
Stable explicit schemes for equations of Schroedinger type
NASA Technical Reports Server (NTRS)
Mickens, Ronald E.
1989-01-01
A method for constructing explicit finite-difference schemes which can be used to solve Schroedinger-type partial-differential equations is presented. A forward Euler scheme that is conditionally stable is given by the procedure. The results presented are based on the analysis of the simplest Schroedinger type equation.
Implicit and Explicit Learning in Young Adults with Mental Retardation.
ERIC Educational Resources Information Center
Atwell, Julie A.; Conners, Frances A.; Merrill, Edward C.
2003-01-01
Young adults with (n=34) and without (n=41) mental retardation completed a sequence-learning and identification task. For some, sequences were constructed following an artificial grammar. Explicit learning was determined by ability to learn and identify random sequences, implicit learning by the tendency to identify incorrectly new grammatical…
Xiao, Deli; Zhang, Chan; He, Jia; Zeng, Rong; Chen, Rong; He, Hua
2016-01-01
Simple, accurate and high-throughput pretreatment method would facilitate large-scale studies of trace analysis in complex samples. Magnetic mixed hemimicelles solid-phase extraction has the power to become a key pretreatment method in biological, environmental and clinical research. However, lacking of experimental predictability and unsharpness of extraction mechanism limit the development of this promising method. Herein, this work tries to establish theoretical-based experimental designs for extraction of trace analytes from complex samples using magnetic mixed hemimicelles solid-phase extraction. We selected three categories and six sub-types of compounds for systematic comparative study of extraction mechanism, and comprehensively illustrated the roles of different force (hydrophobic interaction, π-π stacking interactions, hydrogen-bonding interaction, electrostatic interaction) for the first time. What’s more, the application guidelines for supporting materials, surfactants and sample matrix were also summarized. The extraction mechanism and platform established in the study render its future promising for foreseeable and efficient pretreatment under theoretical based experimental design for trace analytes from environmental, biological and clinical samples. PMID:27924944
NASA Astrophysics Data System (ADS)
Xiao, Deli; Zhang, Chan; He, Jia; Zeng, Rong; Chen, Rong; He, Hua
2016-12-01
Simple, accurate and high-throughput pretreatment method would facilitate large-scale studies of trace analysis in complex samples. Magnetic mixed hemimicelles solid-phase extraction has the power to become a key pretreatment method in biological, environmental and clinical research. However, lacking of experimental predictability and unsharpness of extraction mechanism limit the development of this promising method. Herein, this work tries to establish theoretical-based experimental designs for extraction of trace analytes from complex samples using magnetic mixed hemimicelles solid-phase extraction. We selected three categories and six sub-types of compounds for systematic comparative study of extraction mechanism, and comprehensively illustrated the roles of different force (hydrophobic interaction, π-π stacking interactions, hydrogen-bonding interaction, electrostatic interaction) for the first time. What’s more, the application guidelines for supporting materials, surfactants and sample matrix were also summarized. The extraction mechanism and platform established in the study render its future promising for foreseeable and efficient pretreatment under theoretical based experimental design for trace analytes from environmental, biological and clinical samples.
Xiao, Deli; Zhang, Chan; He, Jia; Zeng, Rong; Chen, Rong; He, Hua
2016-12-07
Simple, accurate and high-throughput pretreatment method would facilitate large-scale studies of trace analysis in complex samples. Magnetic mixed hemimicelles solid-phase extraction has the power to become a key pretreatment method in biological, environmental and clinical research. However, lacking of experimental predictability and unsharpness of extraction mechanism limit the development of this promising method. Herein, this work tries to establish theoretical-based experimental designs for extraction of trace analytes from complex samples using magnetic mixed hemimicelles solid-phase extraction. We selected three categories and six sub-types of compounds for systematic comparative study of extraction mechanism, and comprehensively illustrated the roles of different force (hydrophobic interaction, π-π stacking interactions, hydrogen-bonding interaction, electrostatic interaction) for the first time. What's more, the application guidelines for supporting materials, surfactants and sample matrix were also summarized. The extraction mechanism and platform established in the study render its future promising for foreseeable and efficient pretreatment under theoretical based experimental design for trace analytes from environmental, biological and clinical samples.
Design, construction, and testing of a five active axes magnetic bearing system
NASA Technical Reports Server (NTRS)
Delprete, Cristiana; Genta, Giancarlo; Carabelli, Stefano
1994-01-01
A high speed electric spindle based on active electromagnetic suspension technology has been designed, built, and tested. The main goal of the research work was the construction of a highly modular unit which can be used for teaching and research purposes. The design of the electromechanical components and of the control unit is described in detail, together with the characterization tests performed on the various subsystems. A description of the preliminary tests on the unit, conducted at speeds not in excess of the first deformation critical speed of the rotor, concludes the work.
Byron, O
1997-01-01
Computer software such as HYDRO, based upon a comprehensive body of theoretical work, permits the hydrodynamic modeling of macromolecules in solution, which are represented to the computer interface as an assembly of spheres. The uniqueness of any satisfactory resultant model is optimized by incorporating into the modeling procedure the maximal possible number of criteria to which the bead model must conform. An algorithm (AtoB, for atoms to beads) that permits the direct construction of bead models from high resolution x-ray crystallographic or nuclear magnetic resonance data has now been formulated and tested. Models so generated then act as informed starting estimates for the subsequent iterative modeling procedure, thereby hastening the convergence to reasonable representations of solution conformation. Successful application of this algorithm to several proteins shows that predictions of hydrodynamic parameters, including those concerning solvation, can be confirmed. PMID:8994627
Construction of two qutrit entanglement by using magnetic resonance selective pulse sequences
NASA Astrophysics Data System (ADS)
Çorbaci, Sevcan; Doğuş Karakaş, Mikail; Gençten, Azmi
2016-10-01
Quantum entanglement is essential for some applications of quantum information processing such as quantum cryptography, quantum teleportation and superdence coding. A qubit is a two level quantum system and four two-qubit entangled states called Bell states can be easily obtained for two-qubit states. A qutrit is a three level quantum system and Zeeman levels of spin-1 electron or nucleus can be referred as qutrit. For SI (S=1, I=1) spin system there exist nine two-qutrit states. So nine two-qutrit entangled states can be obtained by using the Hadamard and CNOT logic gates. In this study by considering N+@C60 molecule as SI (S=1, I=1) spin system, two-qutrit entangled states are also obtained by using the magnetic resonance selective pulse sequences of Hadamard and CNOT logic gates. Then it is shown that these entangled states can be transformed into each other by the suggested transformation operators.
Use of magnetic micro-cantilevers to study the dynamics of 3D engineered smooth muscle constructs
NASA Astrophysics Data System (ADS)
Liu, Alan; Zhao, Ruogang; Copeland, Craig; Chen, Christopher; Reich, Daniel
2013-03-01
The normal and pathological response of arterial tissue to mechanical stimulus sheds important light on such conditions as atherosclerosis and hypertension. While most previous methods of determining the biomechanical properties of arteries have relied on excised tissue, we have devised a system that enables the growth and in situ application of forces to arrays of stable suspended microtissues consisting of arterial smooth muscle cells (SMCs). Briefly, this magnetic microtissue tester system consists of arrays of pairs of elastomeric magnetically actuated micro-cantilevers between which SMC-infused 3D collagen gels self-assemble and remodel into aligned microtissue constructs. These devices allow us to simultaneously apply force and track stress-strain relationships of multiple microtissues per substrate. We have studied the dilatory capacity and subsequent response of the tissues and find that the resulting stress-strain curves show viscoelastic behavior as well as a linear dynamic recovery. These results provide a foundation for elucidating the mechanical behavior of this novel model system as well as further experiments that simulate pathological conditions. Supported in part by NIH grant HL090747.
Yan, Xuejie; Song, Xiaoyan; Wang, Zhenbo
2017-05-01
The purpose of the study was to construct specific magnetic resonance imaging (MRI)/optical dual-modality molecular probe. Tumor-bearing animal models were established. MRI/optical dual-modality molecular probe was construed by coupling polyethylene glycol (PEG)-modified nano-Fe3O4 with specific targeted cyclopeptide GX1 and near-infrared fluorescent dyes Cy5.5. MRI/optical imaging effects of the probe were observed and the feasibility of in vivo double-modality imaging was discussed. It was found that, the double-modality probe was of high stability; tumor signal of the experimental group tended to be weak after injection of the probe, but rose to a level which was close to the previous level after 18 h (p > 0.05). We successively completed the construction of an ideal MRI/optical dual-modality molecular probe. MRI/optical dual-modality molecular probe which can selectively gather in gastric cancer is expected to be a novel probe used for diagnosing gastric cancer in the early stage.
Construction and initial results from the magnetic diagnostics of the RWM
NASA Astrophysics Data System (ADS)
Bergerson, Will; Forest, C. B.; Hannum, D.; Kendrick, R. D.; Lovell, T. W.; Oliva, S. P.; Sarff, J. S.
2003-10-01
A new experiment to test the stabilization of the Resistive Wall Mode (RWM) by differentially rotating conducting shells surrounding the plasma is beginning operation. The geometry is a linear screw pinch. The first phase will study the RWM without the secondary rotating shell. The second phase will add a second outer shell to be spun. Theory indicates that the ideal kink, unstable with a stationary shell, can be stabilized with an adequate rotation speed applied to a second overlying shell. The plasma's current density, safety factor profiles, and production is controlled by the plasma gun array. The main RWM diagnostic tool is a 2D array of 80 magnetic field sensors on the outer surface of the inner copper shell. Flexible circuit technology allows the array to be wrapped around the column with a substrate that performs sturdily under high temperature applications. The array provides complete surface area coverage of the column and allows for rapid installation and removal to facilitate alterations to the primary shell. Design specifications afford sub-Gauss sensitivity. Initially, the experiment will map the RWM under a variety of plasma conditions without the secondary spinning shell. Once characterized, the second shell will be incorporated and the RWM features mapped again. Initial results will be presented. This work is supported by the US DOE DE-FG02-00ER54603
Self-construction of magnetic hollow La0.7Sr0.3MnO3 microspheres with complex units.
Chu, Xuefeng; Huang, Keke; Han, Mei; Feng, Shouhua
2013-04-15
Perovskite structure La0.7Sr0.3MnO3 magnetic hollow microspheres with complex units were prepared via the hydrothermal route without hard and soft templates. The formation of hollow microspheres follows the self-construction mechanism involving oriented attachment, dissolution, and recrystallization processes. It exhibits a ferromagnetic behavior at room temperature.
Implicit and Explicit Learning of Languages.
ERIC Educational Resources Information Center
McDermott, James E.
1999-01-01
Discusses theoretical and practical issues connected with implicit and explicit learning of languages. Explicit learning is knowledge expressed in the form of rules or definitions; implicit knowledge can be inferred to exist because of observed performance but cannot be clearly described. Hypothesizes why explicit learning can lead to implicit…
ERIC Educational Resources Information Center
Yang, Pei-Ling; Wang, Ai-Ling
2015-01-01
The present study aims to investigate the relationship among EFL college learners' language learning strategies, English self-efficacy, and explicit strategy instruction from the perspectives of Social Cognitive Theory. Three constructs, namely language learning strategies, English learning self-efficacy, and explicit strategy instruction, were…
Implicit Knowledge, Explicit Knowledge, and Achievement in Second Language (L2) Spanish
ERIC Educational Resources Information Center
Gutierrez, Xavier
2012-01-01
Implicit and explicit knowledge of the second language (L2) are two central constructs in the field of second language acquisition (SLA). In recent years, there has been a renewed interest in obtaining valid and reliable measures of L2 learners' implicit and explicit knowledge (e.g., Bowles, 2011; R. Ellis, 2005). The purpose of the present study…
Perspective: Explicitly correlated electronic structure theory for complex systems
NASA Astrophysics Data System (ADS)
Grüneis, Andreas; Hirata, So; Ohnishi, Yu-ya; Ten-no, Seiichiro
2017-02-01
The explicitly correlated approach is one of the most important breakthroughs in ab initio electronic structure theory, providing arguably the most compact, accurate, and efficient ansatz for describing the correlated motion of electrons. Since Hylleraas first used an explicitly correlated wave function for the He atom in 1929, numerous attempts have been made to tackle the significant challenges involved in constructing practical explicitly correlated methods that are applicable to larger systems. These include identifying suitable mathematical forms of a correlated wave function and an efficient evaluation of many-electron integrals. R12 theory, which employs the resolution of the identity approximation, emerged in 1985, followed by the introduction of novel correlation factors and wave function ansätze, leading to the establishment of F12 theory in the 2000s. Rapid progress in recent years has significantly extended the application range of explicitly correlated theory, offering the potential of an accurate wave-function treatment of complex systems such as photosystems and semiconductors. This perspective surveys explicitly correlated electronic structure theory, with an emphasis on recent stochastic and deterministic approaches that hold significant promise for applications to large and complex systems including solids.
An explicit solution for static unbounded helical dynamos
NASA Astrophysics Data System (ADS)
Chen, Pisin; Milovich, Jose L.
The Lortz dynamo with helical symmetry is re-examined. It is shown that by imposing appropriate boundary conditions the set of possible solutions can be broken down into various classes characterized by the behavior of the mean magnetic field. It is found that, as the cylindrical radius, s, tends to zero, 0(sj),
Trakic, Adnan; Weber, Ewald; Li, Bing Keong; Wang, Hua; Liu, Feng; Engstrom, Craig; Crozier, Stuart
2012-04-01
While recent studies have shown that rotating a single radio-frequency (RF) coil during the acquisition of magnetic resonance (MR) images provides a number of hardware advantages (i.e., requires only one RF channel, avoids coil-coil coupling and facilitates large-scale multinuclear imaging), they did not describe in detail how to build a rotating RF coil system. This paper presents detailed engineering information on the electromechanical design and construction of a MR-compatible RRFC system for human head imaging at 2 T. A custom-made (bladeless) pneumatic Tesla turbine was used to rotate the RF coil at a constant velocity, while an infrared optical encoder measured the selected frequency of rotation. Once the rotating structure was mechanically balanced and the compressed air supply suitably regulated, the maximum frequency of rotation measured ~14.5 Hz with a 2.4% frequency variation over time. MR images of a water phantom and human head were obtained using the rotating RF head coil system.
NASA Astrophysics Data System (ADS)
Peng, Fengping; Zhou, Qiang; Lu, Chunhua; Ni, Yaru; Kou, Jiahui; Xu, Zhongzi
2017-02-01
ZnO nanosheet arrays with exposed (001) facets have been constructed onto a biomimetic inner-motile film, using a seed-mediated hydrothermal growth technology without adding capping agents. The growth of ZnO nanoparticles along the [001] direction is impeded because of a physical steric hindrance, and therefore (001) planes are left behind as the dominant crystal facets. In comparison to ZnO nanorod arrays film, the photocatalytic activity of the actuated (001) facets exposed ZnO nanosheet arrays film is dramatically improved to approximately 2.48 times. Moreover, when it is subjected to a rotational magnetic field, the ZnO nanosheet arrays film is driven to mimic ciliary motion like nature beating cilia, which can boost the interior mass transfer and help to promote release of active sites for improving the photocatalytic activity. As a consequence of the exposed (001) high active facets, the singular ability of microfluidic manipulation has greater effect on ZnO nanosheet arrays films. The enhancement of photocatalytic activity of the actuated ZnO nanosheet arrays film is much more than that of ZnO nanorod arrays film.
Dynamics of electrons and explicit solutions of Dirac–Weyl systems
NASA Astrophysics Data System (ADS)
Sakhnovich, Alexander
2017-03-01
Explicit solutions of the Dirac–Weyl system, which are essential in graphene studies, are constructed using our recent approach to the construction of solutions of dynamical systems. The obtained classes of solutions are much wider than the ones which have been considered before. It is proved that neither the constructed potentials nor the corresponding solutions have singularities. Various examples are provided.
Dong, Yuanyuan; Zhang, Lei
2017-03-18
The different morphologies of magnetic nickel cobaltate (NiCo2O4) electrocatalysts, consisting of nanoparticles (NiCo2O4-N), nanoplates (NiCo2O4-P) and microspheres (NiCo2O4-S) were fabricated. It was found that the electrocatalytic properties of the sensing materials were strongly dependent on morphology and specific surface area. The porous NiCo2O4 hexagonal nanoplates coupled with ILs as modified materials (ILs@NiCo2O4-P) for the simultaneous determination of thallium (Tl(+)), lead (Pb(2+)) and copper (Cu(2+)), exhibited high sensitivity, long-time stability and good repeatability. The enhanced electrocatalytic activity was attributed to relatively large specific surface area, excellent electronic conductivity, and unique porous nanostructure. The analytical performance of the constructed electrode on detection of Tl(+), Pb(2+) and Cu(2+) was examined using differential pulse anodic stripping voltammetry (DPASV). Under optimal conditions, the electrode showed a good linear response to Tl(+), Pb(2+)and Cu(2+) in the concentration range of 0.1-100.0, 0.1-100.0 and 0.05-100.0μg/L, respectively. The detection limits (S/N=3) were 0.046, 0.034 and 0.029μg/L for Tl(+), Pb(2+) and Cu(2+), respectively. The fabricated sensor was successfully applied to detect trace Tl(+), Pb(2+) and Cu(2+) in various water and soil samples with satisfactory results. Hence, this work provided a promising material for electrochemical determination of cumulative toxic metals individually and simultaneously.
NASA Astrophysics Data System (ADS)
Fujisawa, Takumi; Yamaguchi, Akira; Motoyama, Gaku; Kawakatsu, Daichi; Sumiyama, Akihiko; Takeuchi, Tetsuya; Settai, Rikio; Ōnuki, Yoshichika
2015-04-01
We report magnetization of a non-centrosymmetric superconductor, LaPt3Si below 0.6 K up to 200 Oe. The home-made SQUID and Hall sensor magnetometers that operate below 1 K were constructed for this purpose. Although the SQUID magnetometer is more sensitive than the Hall sensor’s one, it was found not to work correctly for the rapid magnetization change of LaPt3Si below 0.4 K. The Hall sensor magnetometer, in contrast, can properly detect magnetization jumps in the M-H curve of the superconducting state. The observed flux jumps are probably related to the interfusion of the mixed state of the LaPt3Si that is observed in the μSR measurements.
Development of Implicit and Explicit Category Learning
ERIC Educational Resources Information Center
Huang-Pollock, Cynthia L.; Maddox, W. Todd; Karalunas, Sarah L.
2011-01-01
We present two studies that examined developmental differences in the implicit and explicit acquisition of category knowledge. College-attending adults consistently outperformed school-age children on two separate information-integration paradigms due to children's more frequent use of an explicit rule-based strategy. Accuracy rates were also…
Implicit and Explicit Exercise and Sedentary Identity
ERIC Educational Resources Information Center
Berry, Tanya R.; Strachan, Shaelyn M.
2012-01-01
We examined the relationship between implicit and explicit "exerciser" and "sedentary" self-identity when activated by stereotypes. Undergraduate participants (N = 141) wrote essays about university students who either liked to exercise or engage in sedentary activities. This was followed by an implicit identity task and an explicit measure of…
Thinking Styles in Implicit and Explicit Learning
ERIC Educational Resources Information Center
Xie, Qiuzhi; Gao, Xiangping; King, Ronnel B.
2013-01-01
This study investigated whether individual differences in thinking styles influence explicit and implicit learning. Eighty-seven university students in China participated in this study. Results indicated that performance in the explicit learning condition was positively associated with Type I thinking styles (i.e. legislative and liberal styles)…
Implicit and Explicit Instruction of Spelling Rules
ERIC Educational Resources Information Center
Kemper, M. J.; Verhoeven, L.; Bosman, A. M. T.
2012-01-01
The study aimed to compare the differential effectiveness of explicit and implicit instruction of two Dutch spelling rules. Students with and without spelling disabilities were instructed a spelling rule either implicitly or explicitly in two experiments. Effects were tested in a pretest-intervention-posttest control group design. Experiment 1…
Hofacker, H.B.
1958-09-23
This patent relates to nmgnets used in a calutron and more particularly to means fur clamping an assembly of magnet coils and coil spacers into tightly assembled relation in a fluid-tight vessel. The magnet comprises windings made up of an assembly of alternate pan-cake type coils and spacers disposed in a fluid-tight vessel. At one end of the tank a plurality of clamping strips are held firmly against the assembly by adjustable bolts extending through the adjacent wall. The foregoing arrangement permits taking up any looseness which may develop in the assembly of coils and spacers.
Stability of explicit advection schemes. The balance point location rule
NASA Astrophysics Data System (ADS)
Leonard, B. P.
2002-02-01
This paper introduces the balance point location rule, providing specific necessary and sufficient conditions for constructing unconditionally stable explicit advection schemes, in both semi-Lagrangian and flux-form Eulerian formulations. The rule determines how the spatial stencil is placed on the computational grid. It requires the balance point (the center of the stencil in index space) to be located in the same patch as the departure point for semi-Lagrangian schemes or the same cell as the sweep point for Eulerian schemes. Centering the stencil in this way guarantees stability, regardless of the size of the time step. In contrast, the original Courant-Friedrichs-Lewy (CFL) condition requiring the stencil merely to include the departure (sweep) point, although necessary, is not sufficient for guaranteeing stability. The CFL condition is of limited practical value, whereas the balance point location rule always gives precise and easily implemented prescriptions for constructing stable algorithms. The rule is also helpful in correcting a number of misconceptions that have arisen concerning explicit advection schemes. In particular, explicit Eulerian schemes are widely believed to be inefficient because of stability constraints on the time step, dictated by a narrow interpretation of the CFL condition requiring the Courant number to be less than or equal to one. However, such constraints apply only to a particular class of advection schemes resulting for centering the stencil on the arrival point, when in fact the sole function of the stencil is to estimate the departure (sweep) point value - the arrival point has no relevance in determining the placement of the stencil. Unconditionally stable explicit Eulerian advection schemes are efficient and accurate, comparable in operation count to semi-Lagrangian schemes of the same order, but because of their flux-based formulation, they have the added advantage of being inherently conservative. Copyright
Quasideterminant solutions of the generalized Heisenberg magnet model
NASA Astrophysics Data System (ADS)
Saleem, U.; Hassan, M.
2010-01-01
In this paper we present the Darboux transformation for the generalized Heisenberg magnet (GHM) model based on the general linear Lie group GL(n) and construct multi-soliton solutions in terms of quasideterminants. Further we relate the quasideterminant multi-soliton solutions obtained by means of Darboux transformation with those obtained by the dressing method. We also discuss the model based on the Lie group SU(n) and obtain explicit soliton solutions of the model based on SU(2).
NASA Astrophysics Data System (ADS)
Haltia-Hovi, E.; Nowaczyk, N.; Lake El'Gygytgyn Scientific Party
2010-12-01
Lake El'gygytgyn (67°30'N 172°00'E; 12 km in diameter; maximum depth 175 m) occupies a meteorite impact crater formed ca. 3.6 Ma ago in Western Beringia, Northeastern Siberia. The area is assumed to have escaped Quaternary glaciations, and the sediments deposited in the basin are anticipated to preserve a unique terrestrial paleoclimatic record extending until the early part of Late Pliocene. Pilot study on the sediments from Lake El'gygytgyn started in the year 1998 showed that magnetic susceptibility (κLF) is responding to variations in Northern Hemisphere insolation during the last 250 kyr (Nowaczyk et al., 2007). Encouraged by the results from the pilot study, new cores were retrieved from the lake in the frame of a joint ICDP El'gygytgyn Drilling Project in spring 2009, when sediments were cored to the depth of 318 meters reaching the impact rocks underlying the sediments. At present, sediments are subjected to intensive study of their physical, biological and chemical proxies to reveal arctic climatic history as recorded by the sediments. κLF is measured on split core surfaces at 1 mm intervals, and it shows pronounced highs and lows with values generally ranging between 0.1 to 3.0*1000 (10-6 SI). To investigate magnetostratigraphy, U-channel samples have been taken from the sediments cored from two parallel coring sites, and measurements of NRM and its AF demagnetization are underway to construct an age model for the sediments based on polarity changes. The polarity sequence established heretofore reveals a clear pattern of magnetozones with normal/reversed polarity, where B/M boundary (0.781 Ma), Jaramillo subchron (from 1.072 to 0.988 Myr) and the termination of Olduvai subchron (1.778 Ma) are manifested distinctly in the data. NRM values range between 0.001 and 0.1 A/m, and magnetizations of low intensity coincide with more complicated magnetizations with multiple components. Information on mineral magnetic properties have been collected from discrete
Implicit sequence learning with competing explicit cues.
Jiménez, L; Méndez, C
2001-05-01
Previous research has shown that the expression of implicit sequence learning is eliminated in a choice reaction time task when an explicit cue allows participants to accurately predict the next stimulus (Cleeremans, 1997), but that two contingencies predicting the same outcome can be learned and expressed simultaneously when both of them remain implicit (Jiménez & Méndez, 1999). Two experiments tested the hypothesis that it is the deliberate use of explicit knowledge that produces the inhibitory effects over the expression of implicit sequence learning. However, the results of these experiments do not support this hypothesis, rather showing that implicit learning is acquired and expressed regardless of the influence of explicit knowledge. These results are interpreted as reinforcing the thesis about the automatic nature of both the acquisition and the expression of implicit sequence learning. The contradictory results reported by Cleeremans are attributed to a floor effect derived from the use of a special type of explicit cue.
An Explicit Nonlinear Mapping for Manifold Learning.
Qiao, Hong; Zhang, Peng; Wang, Di; Zhang, Bo
2013-02-01
Manifold learning is a hot research topic in the held of computer science and has many applications in the real world. A main drawback of manifold learning methods is, however, that there are no explicit mappings from the input data manifold to the output embedding. This prohibits the application of manifold learning methods in many practical problems such as classification and target detection. Previously, in order to provide explicit mappings for manifold learning methods, many methods have been proposed to get an approximate explicit representation mapping with the assumption that there exists a linear projection between the high-dimensional data samples and their low-dimensional embedding. However, this linearity assumption may be too restrictive. In this paper, an explicit nonlinear mapping is proposed for manifold learning, based on the assumption that there exists a polynomial mapping between the high-dimensional data samples and their low-dimensional representations. As far as we know, this is the hrst time that an explicit nonlinear mapping for manifold learning is given. In particular, we apply this to the method of locally linear embedding and derive an explicit nonlinear manifold learning algorithm, which is named neighborhood preserving polynomial embedding. Experimental results on both synthetic and real-world data show that the proposed mapping is much more effective in preserving the local neighborhood information and the nonlinear geometry of the high-dimensional data samples than previous work.
Sleep enhances explicit recollection in recognition memory.
Drosopoulos, Spyridon; Wagner, Ullrich; Born, Jan
2005-01-01
Recognition memory is considered to be supported by two different memory processes, i.e., the explicit recollection of information about a previous event and an implicit process of recognition based on an acontextual sense of familiarity. Both types of memory supposedly rely on distinct memory systems. Sleep is known to enhance the consolidation of memories, with the different sleep stages affecting different types of memory. In the present study, we used the process-dissociation procedure to compare the effects of sleep on estimates of explicit (recollection) and implicit (familiarity) memory formation on a word-list discrimination task. Subjects studied two lists of words before a 3-h retention interval of sleep or wakefulness, and recognition was tested afterward. The retention intervals were positioned either in the early night when sleep is dominated by slow-wave sleep (SWS), or in the late night, when sleep is dominated by REM sleep. Sleep enhanced explicit recognition memory, as compared with wakefulness (P < 0.05), whereas familiarity was not affected by sleep. Moreover, explicit recognition was particularly enhanced after sleep in the early-night retention interval, and especially when the words were presented with the same contextual features as during learning, i.e., in the same font (P < 0.05). The data indicate that in a task that allows separating the contribution of explicit and implicit memory, sleep particularly supports explicit memory formation. The mechanism of this effect appears to be linked to SWS.
NASA Astrophysics Data System (ADS)
Litvinova, Tamara; Kudryavtsev, Ivan
2016-04-01
The paper considers the results of re-interpretation of geophysical data within the water continuation of the Korotaikha depression. To solve the issue of identifying promising areas of oil and gas accumulation in the region, magnetic and gravity materials were reprocessed: digital maps of potential fields at 1: 500 000 scale were compiled on a frame network of seismic lines (3 lines on land and 3 lines in water area) made by reflection-CDP, density models to a depth of 20 km by solving the direct problem of gravity prospecting in GM-SYS module (Geosoft) in 2D formulation were constructed. Deep reflection-CDP seismic sections specified according to the deep wells were used as starting models. Correctness of the selected density models was controlled by comparing the theoretical curve with the values interpolated on the profile line from the digital model of gravity anomaly (Bouguer, density of the intermediate layer of 2.67 g/cm3). Magnetic modeling was performed using geometry of blocks from the obtained density models to a depth of 20 km and is based on selection of local anomaly sources in the upper section (in the Triassic strata). Blocks of the Precambrian basement were used as sources of regional magnetic anomalies in the considered models. Modeling constructs show the defining role of the topography of terrigenous and carbonate complex boundary within the Paleozoic section as a source of gravity anomalies for the region under study. These findings are confirmed by comparison of gravity and seismic data (maps of local gravity anomalies and structural maps of reflecting horizons) and additionally substantiated by analysis of the nature of local magnetic anomalies distribution. The latter are associated with the Triassic basalt horizons at the top of the terrigenous complex and thus also reflect structures of the sedimentary cover, which are registered independently by gravity data.
Explicit K-symplectic algorithms for charged particle dynamics
NASA Astrophysics Data System (ADS)
He, Yang; Zhou, Zhaoqi; Sun, Yajuan; Liu, Jian; Qin, Hong
2017-02-01
We study the Lorentz force equation of charged particle dynamics by considering its K-symplectic structure. As the Hamiltonian of the system can be decomposed as four parts, we are able to construct the numerical methods that preserve the K-symplectic structure based on Hamiltonian splitting technique. The newly derived numerical methods are explicit, and are shown in numerical experiments to be stable over long-term simulation. The error convergency as well as the long term energy conservation of the numerical solutions is also analyzed by means of the Darboux transformation.
Explicit Formula for the Three-Parameter Infiltration Equation
NASA Astrophysics Data System (ADS)
Barry, D. A.; Parlange, J.; Haverkamp, R.
2002-05-01
The two-parameter (i.e., sorptivity and maximum hydraulic conductivity) Green-Ampt (GA) and Talsma-Parlange (TP) infiltration equations bracket the range of possible responses for cumulative water inflow into initially dry or uniformly moist soil profiles. We show that these implicit equations can be represented in explicit form (infiltration as a function of time) using the Lambert W function. Of these formulas, TP has been shown to be closest to measured data. The three-parameter equation was introduced to interpolate between these limits, with α as the interpolating parameter. The GA case corresponds to α = 0 whereas TP results for α = 1. Besides the limiting cases, another exact explicit solution is available for α = 1/2. Guided by the behaviour of the Lambert W function, an analytical iteration scheme is presented for solution of the three-parameter equation. However, by constructing an accurate explicit approximation (maximum relative error less than 0.05%), we show that iteration is not needed in most circumstances. An exception is the one-dimensional intercept, for which one iteration of the analytical approximation might be needed.
Explicit versus spontaneous diffeomorphism breaking in gravity
NASA Astrophysics Data System (ADS)
Bluhm, Robert
2015-03-01
Gravitational theories with fixed background fields break local Lorentz and diffeomorphism invariance either explicitly or spontaneously. In the case of explicit breaking it is known that conflicts can arise between the dynamics and geometrical constraints, while spontaneous breaking evades this problem. It is for this reason that in the gravity sector of the Standard-Model extension (SME) it is assumed that the background fields (SME coefficients) originate from spontaneous symmetry breaking. However, in other examples, such as Chern-Simons gravity and massive gravity, diffeomorphism invariance is explicitly broken by the background fields, and the potential conflicts between the dynamics and geometry can be avoided in most cases. An analysis of how this occurs is given, and the conditions that are placed on the metric tensor and gravitational structure as a result of the presence of an explicit-breaking background are described. The gravity sector of the SME is then considered for the case of explicit breaking. However, it is found that a useful post-Newtonian limit is only obtained when the symmetry breaking is spontaneous.
The Implicit and Explicit alpha-mu Schemes
NASA Technical Reports Server (NTRS)
Chang, Sin-Chung; Himansu, Ananda
1997-01-01
Artificial numerical dissipation is an important issue in large Reynolds number computations. In such computations, the artificial dissipation inherent in traditional numerical schemes can overwhelm the physical dissipation and yield inaccurate results on meshes of practical size. In the present work, the space-time conservation element and solution element method is used to construct new and accurate numerical schemes such that artificial numerical dissipation will not overwhelm physical dissipation. Specifically, these schemes have the property that numerical dissipation vanishes when the physical viscosity goes to zero. These new schemes therefore accurately model the physical dissipation even when it is extremely small. The method of space-time conservation element and solution element, currently under development, is a nontraditional numerical method for solving conservation laws. The method is developed on the basis of local and global flux conservation in a space-time domain, in which space and time are treated in a unified manner. Explicit solvers for model and fluid dynamic conservation laws have previously been investigated. In this paper, we introduce a new concept in the design of implicit schemes, and use it to construct two highly accurate solvers for a convection-diffusion equation. The two schemes become identical in the pure convection case, and in the pure diffusion case. The implicit schemes are applicable over the whole Reynolds number range, from purely diffusive equations to purely inviscid (convective) equations. The stability and consistency of the schemes are analyzed, and some numerical results are presented. It is shown that, in the inviscid case, the new schemes become explicit and their amplification factors are identical to those of the Leapfrog scheme. On the other hand, in the pure diffusion case, their principal amplification factor becomes the amplification factor of the Crank-Nicolson scheme. We also construct an explicit solver
Brain Networks of Explicit and Implicit Learning
Yang, Jing; Li, Ping
2012-01-01
Are explicit versus implicit learning mechanisms reflected in the brain as distinct neural structures, as previous research indicates, or are they distinguished by brain networks that involve overlapping systems with differential connectivity? In this functional MRI study we examined the neural correlates of explicit and implicit learning of artificial grammar sequences. Using effective connectivity analyses we found that brain networks of different connectivity underlie the two types of learning: while both processes involve activation in a set of cortical and subcortical structures, explicit learners engage a network that uses the insula as a key mediator whereas implicit learners evoke a direct frontal-striatal network. Individual differences in working memory also differentially impact the two types of sequence learning. PMID:22952624
Spatially explicit analyses unveil density dependence.
Veldtman, Ruan; McGeoch, Melodie A.
2004-01-01
Density-dependent processes are fundamental in the understanding of species population dynamics. Whereas the benefits of considering the spatial dimension in population biology are widely acknowledged, the implications of doing so for the statistical detection of spatial density dependence have not been examined. The outcome of traditional tests may therefore differ from those that include ecologically relevant locational information on both the prey species and natural enemy. Here, we explicitly incorporate spatial information on individual counts when testing for density dependence between an insect herbivore and its parasitoids. The spatially explicit approach used identified significant density dependence more frequently and in different instances than traditional methods. The form of density dependence detected also differed between methods. These results demonstrate that the explicit consideration of patch location in density-dependence analyses is likely to significantly alter current understanding of the prevalence and form of spatial density dependence in natural populations. PMID:15590593
Does explicit expectation really affect preparation?
Umbach, Valentin J; Schwager, Sabine; Frensch, Peter A; Gaschler, Robert
2012-01-01
Expectation enables preparation for an upcoming event and supports performance if the anticipated situation occurs, as manifested in behavioral effects (e.g., decreased RT). However, demonstrating coincidence between expectation and preparation is not sufficient for attributing a causal role to the former. The content of explicit expectation may simply reflect the present preparation state. We targeted this issue by experimentally teasing apart demands for preparation and explicit expectations. Expectations often originate from our experience: we expect that events occurring with a high frequency in the past are more likely to occur again. In addition to expectation, other task demands can feed into action preparation. In four experiments, frequency-based expectation was pitted against a selective response deadline. In a three-choice reaction time task, participants responded to stimuli that appeared with varying frequency (60, 30, 10%). Trial-by-trial stimulus expectations were either captured via verbal predictions or induced by visual cues. Predictions as well as response times quickly conformed to the variation in stimulus frequency. After two (of five) experimental blocks we forced participants by selective time pressure to respond faster to a less frequent stimulus. Therefore, participants had to prepare for one stimulus (medium frequency) while often explicitly expecting a different one (high frequency). Response times for the less frequent stimulus decreased immediately, while explicit expectations continued to indicate the (unchanged) presentation frequencies. Explicit expectations were thus not just reflecting preparation. In fact, participants responded faster when the stimulus matched the trial-wise expectations, even when task demands discouraged their use. In conclusion, we argue that explicit expectation feeds into preparatory processes instead of being a mere by-product.
Drift Hamiltonian in magnetic coordinates
White, R.B.; Boozer, A.H.; Hay, R.
1982-02-01
A Hamiltonian formulation of the guiding-center drift in arbitrary, steady state, magnetic and electric fields is given. The canonical variables of this formulation are simply related to the magnetic coordinates. The modifications required to treat ergodic magnetic fields using magnetic coordinates are explicitly given in the Hamiltonian formulation.
Explicit Form Focus Instruction: The Effects on Implicit and Explicit Knowledge of ESL Learners
ERIC Educational Resources Information Center
Ebadi, Mandana Rohollahzadeh; Saad, Mohd Rashid Mohd; Abedalaziz, Nabil
2014-01-01
The study examines the effect of explicit form focus instruction and specifically metalinguistic information feedback on the development of both implicit and explicit knowledge of adult English as a Second Language (ESL) learners. Ninety-one subjects at the lower intermediate level were carefully selected through placement test at one of the…
Why Explicit Knowledge Cannot Become Implicit Knowledge
ERIC Educational Resources Information Center
VanPatten, Bill
2016-01-01
In this essay, I review one of the conclusions in Lindseth (2016) published in "Foreign Language Annals." That conclusion suggests that explicit learning and practice (what she called form-focused instruction) somehow help the development of implicit knowledge (or might even become implicit knowledge). I argue for a different…
Children's Tacit and Explicit Understandings of Dinosaurs.
ERIC Educational Resources Information Center
Barba, Robertta H.
The purpose of this cross-age study was to investigate elementary students' (N=120) tacit and explicit understandings of dinosaurs. Detailed analysis of audiotaped interviews of children's performance during a Piagetian-type clinical interview suggests that children's conceptual understandings of dinosaurs are first developed at a tacit level from…
Sleep Enhances Explicit Recollection in Recognition Memory
ERIC Educational Resources Information Center
Drosopoulos, Spyridon; Wagner, Ullrich; Born, Jan
2005-01-01
Recognition memory is considered to be supported by two different memory processes, i.e., the explicit recollection of information about a previous event and an implicit process of recognition based on a contextual sense of familiarity. Both types of memory supposedly rely on distinct memory systems. Sleep is known to enhance the consolidation of…
Explicit Instruction in Core Reading Programs
ERIC Educational Resources Information Center
Reutzel, D. Ray; Child, Angela; Jones, Cindy D.; Clark, Sarah K.
2014-01-01
The purpose of this study was to conduct a content analysis of the types and occurrences of explicit instructional moves recommended for teaching five essentials of effective reading instruction in grades 1, 3, and 5 core reading program teachers' editions in five widely marketed core reading programs. Guided practice was the most frequently…
From Asking to Answering: Making Questions Explicit
ERIC Educational Resources Information Center
Washington, Gene
2006-01-01
"From Asking To Answering: Making Questions Explicit" describes a pedagogical procedure the author has used in writing classes (expository, technical and creative) to help students better understand the purpose, and effect, of text-questions. It accomplishes this by means of thirteen discrete categories (e.g., CLAIMS, COMMITMENT, ANAPHORA, or…
Uncertainty in spatially explicit animal dispersal models
Mooij, Wolf M.; DeAngelis, Donald L.
2003-01-01
Uncertainty in estimates of survival of dispersing animals is a vexing difficulty in conservation biology. The current notion is that this uncertainty decreases the usefulness of spatially explicit population models in particular. We examined this problem by comparing dispersal models of three levels of complexity: (1) an event-based binomial model that considers only the occurrence of mortality or arrival, (2) a temporally explicit exponential model that employs mortality and arrival rates, and (3) a spatially explicit grid-walk model that simulates the movement of animals through an artificial landscape. Each model was fitted to the same set of field data. A first objective of the paper is to illustrate how the maximum-likelihood method can be used in all three cases to estimate the means and confidence limits for the relevant model parameters, given a particular set of data on dispersal survival. Using this framework we show that the structure of the uncertainty for all three models is strikingly similar. In fact, the results of our unified approach imply that spatially explicit dispersal models, which take advantage of information on landscape details, suffer less from uncertainly than do simpler models. Moreover, we show that the proposed strategy of model development safeguards one from error propagation in these more complex models. Finally, our approach shows that all models related to animal dispersal, ranging from simple to complex, can be related in a hierarchical fashion, so that the various approaches to modeling such dispersal can be viewed from a unified perspective.
Topology of Saturn's main magnetic field
NASA Astrophysics Data System (ADS)
Acuna, M. H.; Connerney, J. E. P.; Ness, N. F.
1981-08-01
The reported analysis of Saturn's main magnetic field takes into account the data obtained by Voyager 1 during its close flyby of Saturn in November 1980. A magnetic field model for the analysis of Saturn's main field in which the distributed ring currents are explicitly modelled is constructed. The considered internal field parameters constitute a first approximation to Saturn's main field. Several model current systems that might be expected on physical grounds to be active in Saturn's magnetosphere are considered. It is pointed out that certain aspects of Saturn's main magnetic field relevant to the planet's interior have been discussed by Stevenson (1980). In particular, the unexpectedly small dipole moment seems to be consistent with the gravitational settling of helium, which leads to a much smaller electrically conducting and convecting region than would be expected of a homogeneous distribution of hydrogen and helium.
Implicit and explicit attitudes toward rape are associated with sexual aggression.
Nunes, Kevin L; Hermann, Chantal A; Ratcliffe, Katie
2013-09-01
We examined the relationship between self-reported sexual aggression and implicit and explicit attitudes towards rape in a sample of 86 male heterosexual university students. Large, significant group differences were found between the most sexually aggressive participants and the nonaggressive participants, with the most sexually aggressive group showing less negative implicit and explicit attitudes towards rape (Cohen's d=0.76-1.20). Implicit and explicit attitudes provided complementary information such that together they were more strongly associated with sexual aggression than on their own. The current findings suggest that implicit and explicit attitudes towards rape are associated with sexual aggression. In addition to the broader set of cognitions that appear to be assessed by most self-report measures, the narrower construct of attitudes towards rape may be a fruitful avenue of further exploration for research, assessment, and treatment of sexual aggression.
Explicit synchronisation of heterogeneous dynamics networks via three-layer communication framework
NASA Astrophysics Data System (ADS)
Wang, Bohui; Wang, Jingcheng; Zhang, Langwen; Zhang, Bin
2016-06-01
This paper addresses the explicit synchronisation of heterogeneous dynamics networks via three-layer communication framework. The main contribution is to propose an explicit synchronisation algorithm, in which the synchronisation errors of all the agents are decoupled. By constructing a three-layer node model, the proposed algorithm removes the assumptions that the topology is fixed and the synchronisation process is coupled. By introducing appropriate assumptions, the algorithm leads to a class of explicit synchronisation protocols based on the states of agents in different layers. It is proved in the sense of Lyapunov that, if the dwell time is larger than a threshold, the explicit synchronisation can be achieved for closed-loop heterogeneous dynamics networks under switching topologies. The results are further extended to the cases in which the switching topologies are only frequently but not always connected. Simulation results are presented with four single-link manipulators to verify the theoretical analysis.
Mashhadi Malekzadeh, Asemeh; Ramazani, Ali; Tabatabaei Rezaei, Seyed Jamal; Niknejad, Hassan
2017-03-15
Magnetic drug targeting is a drug delivery strategy that can be used to improve the therapeutic efficiency on tumor cells and reduce the side effects on normal cells and tissues. The aim in this study is designing a novel multifunctional drug delivery system based on superparamagnetic nanoparticles for cancer therapy. Magnetic nanoparticles were synthesized by coprecipitation of iron oxide followed by coating with poly citric acid (PCA) dendritic macromolecules via bulk polymerization strategy. It was further surface-functionalized with poly(ethylene glycol) (PEG) and then to achieve tumor cell targeting property, folic acid was further incorporated to the surface of prepared carriers via a facile coupling reaction between the hydroxyl end group of the PEG and the carboxyl group of folic acid. The so prepared nanocarriers (Fe3O4@PCA-PEG-FA) were characterized by X-ray diffraction, TEM, TGA, FT-IR, DLS and VSM techniques. The room temperature VSM measurements showed that magnetic particles were superparamagnetic. Transmission electron microscopy and dynamic light scattering were also performed which revealed that size of nanocarriers was lying in the range of 10-49nm. Quercetin loading and release profiles of prepared nanocarriers showed that up to 83% of loaded drug was released in 250h. Fluorescent microscopy showed that the cellular uptake by folate receptor-overexpressing HeLa cells of the quercetin-loaded Fe3O4@PCA-PEG-FA nanoparticles was higher than that of non-folate conjugated nanoparticles. Thus, folate conjugation significantly increased nanoparticle cytotoxicity. Also, T2-weighted MRI images of Fe3O4@PCA-PEG-FA nanoparticles showed that the magnetic resonance signal is enhanced significantly with increasing nanoparticle concentration in water and they also served as MRI contrast agents with relaxivities of 3.4mM(-1)s(-1) (r1) and 99.8mM(-1)s(-1) (r2). The results indicate that this multifunctional nanocarrier is a significant breakthrough in developing a
Neural networks underlying implicit and explicit moral evaluations in psychopathy
Yoder, K J; Harenski, C; Kiehl, K A; Decety, J
2015-01-01
Psychopathy, characterized by symptoms of emotional detachment, reduced guilt and empathy and a callous disregard for the rights and welfare of others, is a strong risk factor for immoral behavior. Psychopathy is also marked by abnormal attention with downstream consequences on emotional processing. To examine the influence of task demands on moral evaluation in psychopathy, functional magnetic resonance imaging was used to measure neural response and functional connectivity in 88 incarcerated male subjects (28 with Psychopathy Checklist Revised (PCL-R) scores ⩾30) while they viewed dynamic visual stimuli depicting interpersonal harm and interpersonal assistance in two contexts, implicit and explicit. During the implicit task, high psychopathy was associated with reduced activity in the dorsolateral prefrontal cortex and caudate when viewing harmful compared with helpful social interactions. Functional connectivity seeded in the right amygdala and right temporoparietal junction revealed decreased coupling with the anterior cingulate cortex (ACC), anterior insula, striatum and ventromedial prefrontal cortex. In the explicit task, higher trait psychopathy predicted reduced signal change in ACC and amygdala, accompanied by decreased functional connectivity to temporal pole, insula and striatum, but increased connectivity with dorsal ACC. Psychopathy did not influence behavioral performance in either task, despite differences in neural activity and functional connectivity. These findings provide the first direct evidence that hemodynamic activity and neural coupling within the salience network are disrupted in psychopathy, and that the effects of psychopathy on moral evaluation are influenced by attentional demands. PMID:26305476
Neural networks underlying implicit and explicit moral evaluations in psychopathy.
Yoder, K J; Harenski, C; Kiehl, K A; Decety, J
2015-08-25
Psychopathy, characterized by symptoms of emotional detachment, reduced guilt and empathy and a callous disregard for the rights and welfare of others, is a strong risk factor for immoral behavior. Psychopathy is also marked by abnormal attention with downstream consequences on emotional processing. To examine the influence of task demands on moral evaluation in psychopathy, functional magnetic resonance imaging was used to measure neural response and functional connectivity in 88 incarcerated male subjects (28 with Psychopathy Checklist Revised (PCL-R) scores ⩾ 30) while they viewed dynamic visual stimuli depicting interpersonal harm and interpersonal assistance in two contexts, implicit and explicit. During the implicit task, high psychopathy was associated with reduced activity in the dorsolateral prefrontal cortex and caudate when viewing harmful compared with helpful social interactions. Functional connectivity seeded in the right amygdala and right temporoparietal junction revealed decreased coupling with the anterior cingulate cortex (ACC), anterior insula, striatum and ventromedial prefrontal cortex. In the explicit task, higher trait psychopathy predicted reduced signal change in ACC and amygdala, accompanied by decreased functional connectivity to temporal pole, insula and striatum, but increased connectivity with dorsal ACC. Psychopathy did not influence behavioral performance in either task, despite differences in neural activity and functional connectivity. These findings provide the first direct evidence that hemodynamic activity and neural coupling within the salience network are disrupted in psychopathy, and that the effects of psychopathy on moral evaluation are influenced by attentional demands.
NASA Astrophysics Data System (ADS)
Yoshida, Z.; Mahajan, S. M.
2014-07-01
Adiabatic invariants foliate phase space, and impart a macro-scale hierarchy by separating microscopic variables. On a macroscopic leaf, long-scale ordered structures are created while maximizing entropy. A plasma confined in a magnetosphere is invoked to unveil the organizing principle-in the vicinity of a magnetic dipole, the plasma self-organizes to a state with a steep density gradient. The resulting nontrivial structure has maximum entropy in an appropriate, constrained phase space. One could view such a phase space as a leaf foliated in terms of Casimir invariants-adiabatic invariants measuring the number of quasi-particles (macroscopic representation of periodic motions) are identified as the relevant Casimir invariants. The density clump is created in response to the inhomogeneity of the energy levels (frequencies) of the quasi-particles.
Psychometric intelligence dissociates implicit and explicit learning.
Gebauer, Guido F; Mackintosh, Nicholas J
2007-01-01
The hypothesis that performance on implicit learning tasks is unrelated to psychometric intelligence was examined in a sample of 605 German pupils. Performance in artificial grammar learning, process control, and serial learning did not correlate with various measures of intelligence when participants were given standard implicit instructions. Under an explicit rule discovery instruction, however, a significant relationship between performance on the learning tasks and intelligence appeared. This finding provides support for Reber's hypothesis that implicit learning, in contrast to explicit learning, is independent of intelligence, and confirms thereby the distinction between the 2 modes of learning. However, because there were virtually no correlations among the 3 learning tasks, the assumption of a unitary ability of implicit learning was not supported.
Teleoperations with shared explicit contact force control
NASA Astrophysics Data System (ADS)
Caiti, Andrea; Cannata, Giorgio; Casalino, Giuseppe; Reto, Simone
1997-12-01
In this paper the development of a master-slave robotics system is presented. This development is part of a research project devoted to the intelligent automation of in-service inspection of welded seams in nuclear plants using non- destructive ultrasonic based techniques. The main feature of the system is a shared explicit control scheme of the contact force during the interaction of the end-effector with the remote environment. This unilateral master-slave operational scheme does not suffer from the drawbacks of the bilateral force reflection based implementation. Moreover it avoids the operator from damaging the remote manipulator during wrong maneuvers due to imperfect video feedback. The paper describes the control structure applied (belonging to the class of explicit force control) and the hardware-software architecture of the system. Experimental results are given on the Ansaldo Olasand manipulator.
Parameter and uncertainty estimation for mechanistic, spatially explicit epidemiological models
NASA Astrophysics Data System (ADS)
Finger, Flavio; Schaefli, Bettina; Bertuzzo, Enrico; Mari, Lorenzo; Rinaldo, Andrea
2014-05-01
Epidemiological models can be a crucially important tool for decision-making during disease outbreaks. The range of possible applications spans from real-time forecasting and allocation of health-care resources to testing alternative intervention mechanisms such as vaccines, antibiotics or the improvement of sanitary conditions. Our spatially explicit, mechanistic models for cholera epidemics have been successfully applied to several epidemics including, the one that struck Haiti in late 2010 and is still ongoing. Calibration and parameter estimation of such models represents a major challenge because of properties unusual in traditional geoscientific domains such as hydrology. Firstly, the epidemiological data available might be subject to high uncertainties due to error-prone diagnosis as well as manual (and possibly incomplete) data collection. Secondly, long-term time-series of epidemiological data are often unavailable. Finally, the spatially explicit character of the models requires the comparison of several time-series of model outputs with their real-world counterparts, which calls for an appropriate weighting scheme. It follows that the usual assumption of a homoscedastic Gaussian error distribution, used in combination with classical calibration techniques based on Markov chain Monte Carlo algorithms, is likely to be violated, whereas the construction of an appropriate formal likelihood function seems close to impossible. Alternative calibration methods, which allow for accurate estimation of total model uncertainty, particularly regarding the envisaged use of the models for decision-making, are thus needed. Here we present the most recent developments regarding methods for parameter and uncertainty estimation to be used with our mechanistic, spatially explicit models for cholera epidemics, based on informal measures of goodness of fit.
Extrapolated stabilized explicit Runge-Kutta methods
NASA Astrophysics Data System (ADS)
Martín-Vaquero, J.; Kleefeld, B.
2016-12-01
Extrapolated Stabilized Explicit Runge-Kutta methods (ESERK) are proposed to solve multi-dimensional nonlinear partial differential equations (PDEs). In such methods it is necessary to evaluate the function nt times per step, but the stability region is O (nt2). Hence, the computational cost is O (nt) times lower than for a traditional explicit algorithm. In that way stiff problems can be integrated by the use of simple explicit evaluations in which case implicit methods usually had to be used. Therefore, they are especially well-suited for the method of lines (MOL) discretizations of parabolic nonlinear multi-dimensional PDEs. In this work, first s-stages first-order methods with extended stability along the negative real axis are obtained. They have slightly shorter stability regions than other traditional first-order stabilized explicit Runge-Kutta algorithms (also called Runge-Kutta-Chebyshev codes). Later, they are used to derive nt-stages second- and fourth-order schemes using Richardson extrapolation. The stability regions of these fourth-order codes include the interval [ - 0.01nt2, 0 ] (nt being the number of total functions evaluations), which are shorter than stability regions of ROCK4 methods, for example. However, the new algorithms neither suffer from propagation of errors (as other Runge-Kutta-Chebyshev codes as ROCK4 or DUMKA) nor internal instabilities. Additionally, many other types of higher-order (and also lower-order) methods can be obtained easily in a similar way. These methods also allow adaptation of the length step with no extra cost. Hence, the stability domain is adapted precisely to the spectrum of the problem at the current time of integration in an optimal way, i.e., with minimal number of additional stages. We compare the new techniques with other well-known algorithms with good results in very stiff diffusion or reaction-diffusion multi-dimensional nonlinear equations.
Design of lattice proteins with explicit solvent
NASA Astrophysics Data System (ADS)
Salvi, G.; Mölbert, S.; de Los Rios, P.
2002-12-01
Protein design is important to develop new drugs. As such, a knowledge of the correct model to use to design novel proteins is of the utmost importance. Here we show that a simple model where the solvent degrees of freedom are (semi)explicitly taken into account performs better than other existing models when compared to real data. Some consequences on the criteria to be used for protein design are discussed.
Namba, S.; Hasegawa, N.; Kishimoto, M.; Nishikino, M.; Ishino, M.; Kawachi, T.
2015-11-15
To characterize the temporal evolution of ultrashort X-ray pulses emitted by laser plasmas using a pump-probe method, a magnetic bottle time-of-flight electron spectrometer is constructed. The design is determined by numerical calculations of a mirror magnetic field and of the electron trajectory in a flight tube. The performance of the spectrometer is characterized by measuring the electron spectra of xenon atoms irradiated with a laser-driven plasma X-ray pulse. In addition, two-color above-threshold ionization (ATI) experiment is conducted for measurement of the X-ray laser pulse duration, in which xenon atoms are simultaneously irradiated with an X-ray laser pump and an IR laser probe. The correlation in the intensity of the sideband spectra of the 4d inner-shell photoelectrons and in the time delay of the two laser pulses yields an X-ray pulse width of 5.7 ps, in good agreement with the value obtained using an X-ray streak camera.
Baryon Masses and Hadronic Decay Widths with Explicit Pionic Contributions
NASA Astrophysics Data System (ADS)
Schmidt, R. A.; Canton, L.; Plessas, W.; Schweiger, W.
2017-03-01
We report results from studies of baryon ground and resonant states by taking explicit mesonic degrees of freedom into account. We are following a relativistic coupled-channels approach relying on a Poincaré-invariant mass operator in matrix form. Generally, it corresponds to a bare particle that is coupled to a number of further mesonic channels. Here we present results, where the bare particle is either a bare nucleon or a bare Delta coupled to pion-nucleon and pion-Delta channels, respectively. For the pion-baryon vertices we employ coupling constants and form factors from different models in the literature. From the mass-operator eigenvalue equation we obtain the pion-dressing effects on the nucleon mass as well as the mass and pion-decay width of the Delta. The dressed masses become smaller than the bare ones, and a finite width of the Delta is naturally generated. The results are relevant for the construction of constituent-quark models for baryons, which have so far not included explicit mesonic degrees of freedom, but have rather relied on three-quark configurations only.
Explicit constructivism: a missing link in ineffective lectures?
Prakash, E S
2010-06-01
This study tested the possibility that interactive lectures explicitly based on activating learners' prior knowledge and driven by a series of logical questions might enhance the effectiveness of lectures. A class of 54 students doing the respiratory system course in the second year of the Bachelor of Medicine and Bachelor of Surgery program in my university was randomized to two groups to receive one of two types of lectures, "typical" lectures (n = 28, 18 women and 10 men) or "constructivist" lectures (n = 26, 19 women and 7 men), on the same topic: the regulation of respiration. Student pretest scores in the two groups were comparable (P > 0.1). Students that received the constructivist lectures did much better in the posttest conducted immediately after the lectures (6.8 +/- 3.4 for constructivist lectures vs. 4.2 +/- 2.3 for typical lectures, means +/- SD, P = 0.004). Although both types of lectures were well received, students that received the constructivist lectures appeared to have been more satisfied with their learning experience. However, on a posttest conducted 4 mo later, scores obtained by students in the two groups were not any different (6.9 +/- 3 for constructivist lectures vs. 6.9 +/- 3.7 for typical lectures, P = 0.94). This study adds to the increasing body of evidence that there is a case for the use of interactive lectures that make the construction of knowledge and understanding explicit, easy, and enjoyable to learners.
Tan, Jun; Wei, Xiaoyan; Chen, Jie; Sun, Ping; Ouyang, Yuxia; Fan, Juhong; Liu, Rui
2014-12-10
The present paper constructed and discussed core-shell structured nanospheres grafted with rhodamine based probe for Hg(II) sensing and removal. Electron microscopy images, XRD curves, thermogravimetric analysis and N2 adsorption/desorption isotherms were used to identify the core-shell structure. The inner core consisted of superparamagnetic Fe3O4 nanoparticles, which made the nanocomposite magnetically removable. The outer shell was constructed with silica molecular sieve which provided large surface area and ordered tunnels for the sensing probe, accelerating analyte adsorption and transportation. The rhodamine based sensing probe emission increased with the increasing Hg(II) concentration, showing emission "Off-On" effect, which could be explained by the structural transformation from a non-emissive one to a highly emissive one. The influence from various metal ions and pH values was also investigated, which suggested this structural transformation could only be triggered by Hg(II), showing high selectivity and linear response. The Hg(II) sensing nanocomposite could be regenerated after usage. The response time was slightly compromised and could be further improved.
Wei, Chengzhen; Wang, Lanfang; Dang, Liyun; Chen, Qun; Lu, Qingyi; Gao, Feng
2015-01-01
A bottom-up-then-up-down route was proposed to construct multi-level Bi2S3 hierarchical architectures assembled by two-dimensional (2D) Bi2S3 sheet-like networks. BiOCOOH hollow spheres and flower-like structures, which are both assembled by 2D BiOCOOH nanosheets, were prepared first by a “bottom-up” route through a “quasi-emulsion” mechanism. Then the BiOCOOH hierarchical structures were transferred to hierarchical Bi2S3 architectures through an “up-down” route by an ion exchange method. The obtained Bi2S3 nanostructures remain hollow-spherical and flower-like structures of the precursors but the constructing blocks are changed to 2D sheet-like networks interweaving by Bi2S3 nanowires. The close matching of crystal lattices between Bi2S3 and BiOCOOH was believed to be the key reason for the topotactic transformation from BiOCOOH nanosheets to 2D Bi2S3 sheet-like nanowire networks. Magnetism studies reveal that unlike diamagnetism of comparative Bi2S3 nanostructures, the obtained multi-level Bi2S3 structures display S-type hysteresis and ferromagnetism at low field which might result from ordered structure of 2D networks. PMID:26028331
Wang, Xiu-Li; Zhao, Wei; Zhang, Ju-Wen; Lu, Qi-Lin
2013-02-15
Three new tetranuclear copper(II) cluster-based complexes constructed from 4-amino-1,2,4-triazole (atrz) and three types of aromatic carboxylates, [Cu{sub 4}({mu}{sub 3}-OH){sub 2}(atrz){sub 2}(DNBA){sub 6}] (1), [Cu{sub 4}({mu}{sub 3}-OH){sub 2}(atrz){sub 2}(1,3-BDC){sub 3}]{center_dot}2H{sub 2}O (2) and [Cu{sub 4}({mu}{sub 3}-OH){sub 2}(atrz){sub 2}(SIP){sub 2}]{center_dot}4H{sub 2}O (3) (HDNBA=3,5-dinitrobenzoic acid, 1,3-H{sub 2}BDC=1,3-benzenedicarboxylic acid and NaH{sub 2}SIP=sodium 5-sulfoisophthalate), have been hydrothermally synthesized and structurally characterized. Complex 1 displays a single-molecular Cu{sup II}{sub 4} cluster structure, which is further connected by the intermolecular hydrogen-bonding interactions to form a 2D supramolecular layer. In 2, there also exist tetranuclear Cu{sup II}{sub 4} clusters, which are linked by the 1,3-BDC anions to give a 3D NaCl-type framework. In 3, the Cu{sup II}{sub 4} clusters are connected by the carboxyl and sulfo groups of SIP anions to generate 3D (4,8)-connected framework with a (4{sup 10}{center_dot}6{sup 14}{center_dot}8{sup 4})(4{sup 5}{center_dot}6){sub 2} topology. The atrz ligand conduces to the construction of tetranuclear copper(II) clusters and the carboxylates with different non-carboxyl substituent show important effects on the final structures of the title complexes. The electrochemical and magnetic properties of 1-3 have been investigated. - Graphical abstract: Three tetranuclear copper(II) cluster-based complexes based on different carboxylates have been synthesized under hydrothermal conditions. The carboxylate anions play a key role in the formation of three different structures. Highlights: Black-Right-Pointing-Pointer Three new tetranuclear copper(II) cluster-based complexes have been obtained. Black-Right-Pointing-Pointer The atrz conduces to the construction of tetranuclear copper(II) clusters. Black-Right-Pointing-Pointer Carboxylates show important effect on the structures of
Wu, J.; Scholl, A.; Arenholz, E.; Hwang, C.; Qiu, Z. Q.
2011-01-04
Single crystalline FeMn/Ni bilayer was epitaxially grown on Cu(001) substrate and investigated by photoemission electron microscopy (PEEM). The FeMn and Ni films were grown into two cross wedges to facilitate an independent control of the FeMn (0-20 ML) and Ni (0-20 ML) film thicknesses. The Ni magnetic phases were determined by Ni domain images as a function of the Ni thickness (d{sub Ni}) and the FeMn thickness (d{sub FeMn}). The result shows that as the Ni thickness increases, the Ni film undergoes a paramagnetic-to-ferromagnetic state transition at a critical thickness of d{sub FM} and an in-plane to out-of-plane spin reorientation transition at a thicker thickness d{sub SRT}. The phase diagram shows that both d{sub FM} and d{sub SRT} increase as the FeMn film establishes its antiferromagnetic order.
NASA Astrophysics Data System (ADS)
Zhang, Xiu-Mei; Li, Peng; Gao, Wei; Liu, Feng; Liu, Jie-Ping
2016-12-01
Three lanthanide metal-organic frameworks (Ln-MOFs), [Ln(TZI)(H2O)4]·3H2O (Ln=Gd (1) and Tb (2) and Dy (3), H3TZI=5-(1H-tetrazol-5-yl)isophthalic acid), have been synthesized under hydrothermal conditions. Single crystal X-ray diffraction reveals that 1-3 are isostructural and display a 1D double chain based on dinuclear motifs with (μ-COO)2 double bridges. Magnetic studies indicate antiferromagnetic interactions in 1, ferromagnetic interactions in 2 and 3. Furthermore, compound 3 displays a slow relaxation behavior. Compound 2 exhibits intense characteristic green emission of Tb(III) ions in the solid state, which can be observed by the naked eye under UV light. Interestingly, 2 can selectively sense Pb2+ and Fe3+ ions through luminescence enhancement and quenching, respectively. The luminescence quenching mechanisms have been investigated in detail. The study on luminescence Ln-MOFs as a probe for sensing Pb2+ and Fe3+ ions is exceedingly rare example.
Liu, Panbo; Huang, Ying; Yan, Jing; Yang, Yiwen; Zhao, Yang
2016-03-02
Hybrid nanocomposites with enhanced microwave absorption properties have been designed by growing CuS nanoflakes on magnetically decorated graphene, and the effect of special nanostructures on microwave absorption properties has been investigated. The structure of the nanocomposites was characterized by Fourier transform infrared spectra (FTIR), X-ray diffraction (XRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), N2 adsorption-desorption, and vibrating sample magnetometer (VSM). The influence of cetyltrimethylammonium bromide (CTAB) on the morphology of CuS nanoflakes was also investigated. A possible formation process of the nanocomposites and the mechanism of microwave absorption were explained in detail. As an absorber, the nanocomposites with a filler loading of 20 wt % exhibited enhanced microwave absorption properties due to the special nanostructures, extra void space, and synergistic effect. The maximum reflection loss can reach -54.5 dB at 11.4 GHz, and the absorption bandwidths exceeding -10 dB are 4.5 GHz with a thickness of 2.5 mm, which can be adjusted by the thickness. The results indicate that the hybrid nanocomposites with enhanced microwave absorption properties and lightweight have a promising future in decreasing electromagnetic wave irradiation.
Magnetic quantization over Riemannian manifolds
NASA Astrophysics Data System (ADS)
Karasev, M. V.; Osborn, T. A.
2006-06-01
We demonstrate that Weyl's pioneering idea (1918) to intertwine metric and magnetic fields into a single joint connection can be naturally realized, on the phase space level, by the gauge-invariant quantization of the cotangent bundle with magnetic symplectic form. Quantization, for systems over a noncompact Riemannian configuration manifold, may be achieved by the introduction of a magneto-metric analog of the Stratonovich quantizer - a family of invertible, selfadjoint operators representing quantum delta functions. Based on the quantizer, we construct a generalized Wigner transform that maps Hilbert-Schmidt operators into L-2 phase-space functions. The algebraic properties of the quantizer allow one to extract a family of symplectic reflections, which are then used to (i) derive a simple, explicit, and geometrically invariant formula for the noncommutative product of functions on phase space, and (ii) construct a magneto-metric connection on phase space. The classical limit of this product is given by the usual multiplication of functions (zeroth-order term), the magnetic Poisson bracket (first-order term), and by the magneto-metric connection (second-order term).
Explicit symplectic algorithms based on generating functions for charged particle dynamics.
Zhang, Ruili; Qin, Hong; Tang, Yifa; Liu, Jian; He, Yang; Xiao, Jianyuan
2016-07-01
Dynamics of a charged particle in the canonical coordinates is a Hamiltonian system, and the well-known symplectic algorithm has been regarded as the de facto method for numerical integration of Hamiltonian systems due to its long-term accuracy and fidelity. For long-term simulations with high efficiency, explicit symplectic algorithms are desirable. However, it is generally believed that explicit symplectic algorithms are only available for sum-separable Hamiltonians, and this restriction limits the application of explicit symplectic algorithms to charged particle dynamics. To overcome this difficulty, we combine the familiar sum-split method and a generating function method to construct second- and third-order explicit symplectic algorithms for dynamics of charged particle. The generating function method is designed to generate explicit symplectic algorithms for product-separable Hamiltonian with form of H(x,p)=p_{i}f(x) or H(x,p)=x_{i}g(p). Applied to the simulations of charged particle dynamics, the explicit symplectic algorithms based on generating functions demonstrate superiorities in conservation and efficiency.
Explicit symplectic algorithms based on generating functions for charged particle dynamics
NASA Astrophysics Data System (ADS)
Zhang, Ruili; Qin, Hong; Tang, Yifa; Liu, Jian; He, Yang; Xiao, Jianyuan
2016-07-01
Dynamics of a charged particle in the canonical coordinates is a Hamiltonian system, and the well-known symplectic algorithm has been regarded as the de facto method for numerical integration of Hamiltonian systems due to its long-term accuracy and fidelity. For long-term simulations with high efficiency, explicit symplectic algorithms are desirable. However, it is generally believed that explicit symplectic algorithms are only available for sum-separable Hamiltonians, and this restriction limits the application of explicit symplectic algorithms to charged particle dynamics. To overcome this difficulty, we combine the familiar sum-split method and a generating function method to construct second- and third-order explicit symplectic algorithms for dynamics of charged particle. The generating function method is designed to generate explicit symplectic algorithms for product-separable Hamiltonian with form of H (x ,p ) =pif (x ) or H (x ,p ) =xig (p ) . Applied to the simulations of charged particle dynamics, the explicit symplectic algorithms based on generating functions demonstrate superiorities in conservation and efficiency.
Siengsukon, Catherine F; Al-Sharman, Alham
2011-01-01
Background Healthy young individuals benefit from sleep to promote offline enhancement of a variety of explicitly learned discrete motor tasks. It remains unknown if sleep will promote learning of other types of explicit tasks. The purpose of this study is to verify the role of sleep in learning an explicitly instructed discrete motor task and to determine if participants who practice an explicitly instructed continuous tracking task demonstrate sleep-dependent offline learning of this task. Methods In experiment 1, 28 healthy young adults (mean age 25.6 ± 3.8 years) practiced a serial reaction time (SRT) task at either 8 am (SRT no-sleep group) or 8 pm (SRT sleep group) and underwent retention testing 12 ± 1 hours later. In experiment 2, 20 healthy young individuals (mean age 25.6 ± 3.3 years) practiced a continuous tracking task and were similarly divided into a no-sleep (continuous tracking no-sleep group) or sleep group (continuous tracking sleep group). Individuals in both experiments were provided with explicit instruction on the presence of a sequence in their respective task prior to practice. Results Individuals in the SRT sleep group demonstrated a significant offline reduction in reaction time whereas the SRT no-sleep group did not. Results for experiment 1 provide concurrent evidence that explicitly learned discrete tasks undergo sleep-dependent offline enhancement. Individuals in the continuous tracking sleep group failed to demonstrate a significant offline reduction in tracking error. However, the continuous tracking no-sleep group did demonstrate a significant offline improvement in performance. Results for experiment 2 indicate that sleep is not critical for offline enhancement of an explicit learned continuous task. Conclusion The findings that individuals who practiced an explicitly instructed discrete task experienced sleep-dependent offline learning while those individuals who practiced an explicitly instructed continuous task did not may be
Explicit 3-D Hydrodynamic FEM Program
2000-11-07
DYNA3D is a nonlinear explicit finite element code for analyzing 3-D structures and solid continuum. The code is vectorized and available on several computer platforms. The element library includes continuum, shell, beam, truss and spring/damper elements to allow maximum flexibility in modeling physical problems. Many materials are available to represent a wide range of material behavior, including elasticity, plasticity, composites, thermal effects and rate dependence. In addition, DYNA3D has a sophisticated contact interface capability, including frictional sliding, single surface contact and automatic contact generation.
Tatchyn, Roman; /SLAC
2011-08-12
In recent years studies have been initiated on a new class of multipole field generators consisting of cuboid planar permanent magnet (PM) pieces arranged in biplanar arrays of 2-fold rotational symmetry. These structures, first introduced for Free Electron Laser (FEL) applications, are based on reducing the rotational symmetry of conventional N-pole field generators from N-fold to 2-fold. One consequence of this reduction is a large higher-multipole content in a planar PM multipole's field at distances relatively close to the structure's axis, making it generally unsuitable for applications requiring a large high-quality field aperture. In this paper we outline an economical field-cancellation algorithm that can substantially decrease the harmonic content of a planar PM's field without breaking its biplanar geometry or 2-fold rotational symmetry. An economical field-cancellation algorithm has been described which will allow the fabrication of bi-planar quadrupoles and sextupoles with high-quality fields using a manageably small number of PM pieces. For higher order N-poles the number of pieces required to cancel a given number of successively-higher multipole components will also increase linearly; nevertheless, the practicability of fabricating octupoles and higher N-poles of this type should be considered a subject of continuing r&d. Since the removal of a large number of successive multipole components essentially increases the transverse region over which the N-pole's field is dominated by its leading N-pole field component, the fabrication of quadrupoles and sextupoles of the type described in this paper should lead to their introduction in storage ring applications. One potentially important application in this area is as distributed focusing elements installed into very-short-period, small-gap undulators (e.g., as a FODO lattice). The installation is rendered feasible by the very small vertical height of the biplanar N-poles (on the order of a millimeter
Explicit Runge-Kutta schemes for incompressible flow with improved energy-conservation properties
NASA Astrophysics Data System (ADS)
Capuano, F.; Coppola, G.; Rández, L.; de Luca, L.
2017-01-01
The application of pseudo-symplectic Runge-Kutta methods to the incompressible Navier-Stokes equations is discussed in this work. In contrast to fully energy-conserving, implicit methods, these are explicit schemes of order p that preserve kinetic energy to order q, with q > p. Use of explicit methods with improved energy-conservation properties is appealing for convection-dominated problems, especially in case of direct and large-eddy simulation of turbulent flows. A number of pseudo-symplectic methods are constructed for application to the incompressible Navier-Stokes equations and compared in terms of accuracy and efficiency by means of numerical simulations.
Explicitly represented polygon wall boundary model for the explicit MPS method
NASA Astrophysics Data System (ADS)
Mitsume, Naoto; Yoshimura, Shinobu; Murotani, Kohei; Yamada, Tomonori
2015-05-01
This study presents an accurate and robust boundary model, the explicitly represented polygon (ERP) wall boundary model, to treat arbitrarily shaped wall boundaries in the explicit moving particle simulation (E-MPS) method, which is a mesh-free particle method for strong form partial differential equations. The ERP model expresses wall boundaries as polygons, which are explicitly represented without using the distance function. These are derived so that for viscous fluids, and with less computational cost, they satisfy the Neumann boundary condition for the pressure and the slip/no-slip condition on the wall surface. The proposed model is verified and validated by comparing computed results with the theoretical solution, results obtained by other models, and experimental results. Two simulations with complex boundary movements are conducted to demonstrate the applicability of the E-MPS method to the ERP model.
Spatially explicit modelling of cholera epidemics
NASA Astrophysics Data System (ADS)
Finger, F.; Bertuzzo, E.; Mari, L.; Knox, A. C.; Gatto, M.; Rinaldo, A.
2013-12-01
Epidemiological models can provide crucial understanding about the dynamics of infectious diseases. Possible applications range from real-time forecasting and allocation of health care resources to testing alternative intervention mechanisms such as vaccines, antibiotics or the improvement of sanitary conditions. We apply a spatially explicit model to the cholera epidemic that struck Haiti in October 2010 and is still ongoing. The dynamics of susceptibles as well as symptomatic and asymptomatic infectives are modelled at the scale of local human communities. Dissemination of Vibrio cholerae through hydrological transport and human mobility along the road network is explicitly taken into account, as well as the effect of rainfall as a driver of increasing disease incidence. The model is calibrated using a dataset of reported cholera cases. We further model the long term impact of several types of interventions on the disease dynamics by varying parameters appropriately. Key epidemiological mechanisms and parameters which affect the efficiency of treatments such as antibiotics are identified. Our results lead to conclusions about the influence of different intervention strategies on the overall epidemiological dynamics.
Fully explicit algorithms for fluid simulation
NASA Astrophysics Data System (ADS)
Clausen, Jonathan
2011-11-01
Computing hardware is trending towards distributed, massively parallel architectures in order to achieve high computational throughput. For example, Intrepid at Argonne uses 163,840 cores, and next generation machines, such as Sequoia at Lawrence Livermore, will use over one million cores. Harnessing the increasingly parallel nature of computational resources will require algorithms that scale efficiently on these architectures. The advent of GPU-based computation will serve to accelerate this behavior, as a single GPU contains hundreds of processor ``cores.'' Explicit algorithms avoid the communication associated with a linear solve, thus parallel scalability of these algorithms is typically high. This work will explore the efficiency and accuracy of three explicit solution methodologies for the Navier-Stokes equations: traditional artificial compressibility schemes, the lattice-Boltzmann method, and the recently proposed kinetically reduced local Navier-Stokes equations [Borok, Ansumali, and Karlin (2007)]. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.
Explicit Generation of Orthogonal Grids for Ocean Models
NASA Astrophysics Data System (ADS)
Murray, Ross J.
1996-07-01
Several explicit methods are proposed for generating global orthogonal curvilinear grids for ocean modelling. The methods are based on the conformal properties of stereographic and Mercator map projections and have been developed with the specific object of removing the North Pole from the ocean domain. Some of the configurations, in addition to overcoming the pole problem, have very attractive resolution properties in the polar regions. Two of the constructions are geometrical in nature, while a third is based on the superposition of potential fields generated by discrete coordinate poles. The methods described here differ from those commonly employed in engineering problems in that grid line control is exercised by the placement of a finite number of singularities, and no specific condition is placed upon the fitting of coordinate lines to physical boundaries. The grids produced are accordingly of global construction and have smooth variations in grid size. Being of analytical or semi-analytical formulation, the grids may be generated quickly and without the need for advanced software.
Developmental Comparisons of Implicit and Explicit Language Learning
ERIC Educational Resources Information Center
Lichtman, Karen
2013-01-01
Conventional wisdom holds that children learn languages implicitly whereas older learners learn languages explicitly, and some have claimed that after puberty only explicit language learning is possible. However, older learners often receive more explicit instruction than child L2 learners, which may affect their learning strategies. This study…
ERIC Educational Resources Information Center
Sanz, Cristina; Morgan-Short, Kara
2004-01-01
The facilitative role of explicit information in second language acquisition has been supported by a significant body of research (Alanen, 1995; Carroll & Swain, 1993; de Graaff, 1997; DeKeyser, 1995; Ellis, 1993; Robinson, 1996, 1997), but counterevidence is also available (Rosa & ONeill, 1999; VanPatten & Oikkenon, 1996). This experimental study…
Making explicit the contention in hospice care.
Moon, Paul J
At the core of hospice remains the defining nature of mortals tending to other mortals facing diagnosed terminality. Such situations are pregnant with meanings. As mortals are subjective beings, social engagements become inundated with meaning differences. This alludes to the inescapable occurrence of collisions and conflicts in meaning. It would behoove us to make explicit the contention that exists in hospice care, given that death is the nonnegotiable outcome to be diversely faced by all involved persons whose lived approaches related to death issues may characteristically lack unanimity. Toward elucidating the inherently contentious nature of hospice care, the dynamical influence of external forces that overlie thanatological matters in society and the complex human dynamic in hospice care situations are discussed. Practice suggestions for hospice staff are offered.
Explicit 2-D Hydrodynamic FEM Program
Lin, Jerry
1996-08-07
DYNA2D* is a vectorized, explicit, two-dimensional, axisymmetric and plane strain finite element program for analyzing the large deformation dynamic and hydrodynamic response of inelastic solids. DYNA2D* contains 13 material models and 9 equations of state (EOS) to cover a wide range of material behavior. The material models implemented in all machine versions are: elastic, orthotropic elastic, kinematic/isotropic elastic plasticity, thermoelastoplastic, soil and crushable foam, linear viscoelastic, rubber, high explosive burn, isotropic elastic-plastic, temperature-dependent elastic-plastic. The isotropic and temperature-dependent elastic-plastic models determine only the deviatoric stresses. Pressure is determined by one of 9 equations of state including linear polynomial, JWL high explosive, Sack Tuesday high explosive, Gruneisen, ratio of polynomials, linear polynomial with energy deposition, ignition and growth of reaction in HE, tabulated compaction, and tabulated.
Higher order explicit symmetric integrators for inseparable forms of coordinates and momenta
NASA Astrophysics Data System (ADS)
Liu, Lei; Wu, Xin; Huang, Guoqing; Liu, Fuyao
2016-06-01
Pihajoki proposed the extended phase-space second-order explicit symmetric leapfrog methods for inseparable Hamiltonian systems. On the basis of this work, we survey a critical problem on how to mix the variables in the extended phase space. Numerical tests show that sequent permutations of coordinates and momenta can make the leapfrog-like methods yield the most accurate results and the optimal long-term stabilized error behaviour. We also present a novel method to construct many fourth-order extended phase-space explicit symmetric integration schemes. Each scheme represents the symmetric production of six usual second-order leapfrogs without any permutations. This construction consists of four segments: the permuted coordinates, triple product of the usual second-order leapfrog without permutations, the permuted momenta and the triple product of the usual second-order leapfrog without permutations. Similarly, extended phase-space sixth, eighth and other higher order explicit symmetric algorithms are available. We used several inseparable Hamiltonian examples, such as the post-Newtonian approach of non-spinning compact binaries, to show that one of the proposed fourth-order methods is more efficient than the existing methods; examples include the fourth-order explicit symplectic integrators of Chin and the fourth-order explicit and implicit mixed symplectic integrators of Zhong et al. Given a moderate choice for the related mixing and projection maps, the extended phase-space explicit symplectic-like methods are well suited for various inseparable Hamiltonian problems. Samples of these problems involve the algorithmic regularization of gravitational systems with velocity-dependent perturbations in the Solar system and post-Newtonian Hamiltonian formulations of spinning compact objects.
Zhu, Zude; Fan, Yuanyuan; Feng, Gangyi; Huang, Ruiwang; Wang, Suiping
2013-01-01
Previous studies have indicated that sentences are comprehended via widespread brain regions in the fronto-temporo-parietal network in explicit language tasks (e.g., semantic congruency judgment tasks), and through restricted temporal or frontal regions in implicit language tasks (e.g., font size judgment tasks). This discrepancy has raised questions regarding a common network for sentence comprehension that acts regardless of task effect and whether different tasks modulate network properties. To this end, we constructed brain functional networks based on 27 subjects' fMRI data that was collected while performing explicit and implicit language tasks. We found that network properties and network hubs corresponding to the implicit language task were similar to those associated with the explicit language task. We also found common hubs in occipital, temporal and frontal regions in both tasks. Compared with the implicit language task, the explicit language task resulted in greater global efficiency and increased integrated betweenness centrality of the left inferior frontal gyrus, which is a key region related to sentence comprehension. These results suggest that brain functional networks support both explicit and implicit sentence comprehension; in addition, these two types of language tasks may modulate the properties of brain functional networks.
Reactive Force Fields via Explicit Valency
NASA Astrophysics Data System (ADS)
Kale, Seyit
Computational simulations are invaluable in elucidating the dynamics of biological macromolecules. Unfortunately, reactions present a fundamental challenge. Calculations based on quantum mechanics can predict bond formation and rupture; however they suffer from severe length- and time-limitations. At the other extreme, classical approaches provide orders of magnitude faster simulations; however they regard chemical bonds as immutable entities. A few exceptions exist, but these are not always trivial to adopt for routine use. We bridge this gap by providing a novel, pseudo-classical approach, based on explicit valency. We unpack molecules into valence electron pairs and atomic cores. Particles bear ionic charges and interact via pairwise-only potentials. The potentials are informed of quantum effects in the short-range and obey dissociation limits in the long-range. They are trained against a small set of isolated species, including geometries and thermodynamics of small hydrides and of dimers formed by them. The resulting force field captures the essentials of reactivity, polarizability and flexibility in a simple, seamless setting. We call this model LEWIS, after the chemical theory that inspired the use of valence pairs. Following the introduction in Chapter 1, we initially focus on the properties of water. Chapter 2 considers gas phase clusters. To transition to the liquid phase, Chapter 3 describes a novel pairwise long-range compensation that performs comparably to infinite lattice summations. The approach is suited to ionic solutions in general. In Chapters 4 and 5, LEWIS is shown to correctly predict the dipolar and quadrupolar response in bulk liquid, and can accommodate proton transfers in both acid and base. Efficiency permits the study of proton defects at dilutions not accessible to experiment or quantum mechanics. Chapter 6 discusses explicit valency approaches in other hydrides, forming the basis of a reactive organic force field. Examples of simple
Experiments on Magnetic Materials
ERIC Educational Resources Information Center
Schneider, C. S.; Ertel, John P.
1978-01-01
Describes the construction and use of a simple apparatus to measure the magnetization density and magnetic susceptibility of ferromagnetic, paramagnetic, and the diamagnetic solids and liquids. (Author/GA)
Refinement of protein structures in explicit solvent.
Linge, Jens P; Williams, Mark A; Spronk, Christian A E M; Bonvin, Alexandre M J J; Nilges, Michael
2003-02-15
We present a CPU efficient protocol for refinement of protein structures in a thin layer of explicit solvent and energy parameters with completely revised dihedral angle terms. Our approach is suitable for protein structures determined by theoretical (e.g., homology modeling or threading) or experimental methods (e.g., NMR). In contrast to other recently proposed refinement protocols, we put a strong emphasis on consistency with widely accepted covalent parameters and computational efficiency. We illustrate the method for NMR structure calculations of three proteins: interleukin-4, ubiquitin, and crambin. We show a comparison of their structure ensembles before and after refinement in water with and without a force field energy term for the dihedral angles; crambin was also refined in DMSO. Our results demonstrate the significant improvement of structure quality by a short refinement in a thin layer of solvent. Further, they show that a dihedral angle energy term in the force field is beneficial for structure calculation and refinement. We discuss the optimal weight for the energy constant for the backbone angle omega and include an extensive discussion of meaning and relevance of the calculated validation criteria, in particular root mean square Z scores for covalent parameters such as bond lengths.
Development of explicit criteria for cholecystectomy
Quintana, J; Cabriada, J; d Lopez; Varona, M; Oribe, V; Barrios, B; Arostegui, I; Bilbao, A
2002-01-01
Objective: Consensus development techniques were used in the late 1980s to create explicit criteria for the appropriateness of cholecystectomy. New diagnostic and treatment techniques have been developed in the last decade, so an updated appropriateness of indications tool was developed for cholecystectomy in patients with non-malignant diseases. The validity and reliability of panel results using this tool were tested. Methods: Criteria were developed using a modified Delphi panel judgement process. The level of agreement between the panellists (six gastroenterologists and six surgeons) was analysed and the ratings were compared with those of a second different panel using weighted kappa statistics. Results: The results of the main panel were presented as a decision tree. Of the 210 scenarios evaluated by the main panel in the second round, 51% were found appropriate, 26% uncertain, and 23% inappropriate. Agreement was achieved in 54% of the scenarios and disagreement in 3%. Although the gastroenterologists tended to score fewer scenarios as appropriate, as a group they did not differ from the surgeons. Comparison of the ratings of the main panel with those of a second panel resulted in a weighted kappa statistic of 0.75. Conclusions: The parameters tested showed acceptable validity and reliability results for an evaluation tool. These results support the use of this algorithm as a screening tool for assessing the appropriateness of cholecystectomy. PMID:12468691
Cropp, Roger; Norbury, John
2012-02-07
We synthesize the generic properties of ecologically realistic multi-trophic level models and define criteria for ecological realism. We define an "ecospace" in which all ecologically realistic dynamics are confined, and construct "resource rays" that define the resources available to each species at every point in the ecospace. Resource rays for a species are lines from a vertex of maximum resource to the opposite boundary where no resources are available. The growth functions of all biota normally decrease along their resource rays, and change sign from positive to negative. This property prescribes that each species must have a zero isosurface within the ecospace. We illustrate our conditions on a highly cited three trophic level model from population dynamics, showing how to extend this system biologically consistently to a closed ecological system. Our synthesis extends the concept of carrying capacity of population models to explicitly include exhaustion of limiting resources, and so allows for population biology models to be considered as ecologically closed systems with respect to a key limiting nutrient. This approach unifies many theoretical and applied models in a common biogeochemical framework, facilitates better understanding of the key structures of complex ecologies, and suggests strategies for efficient design of experiments.
Higher-order hybrid implicit/explicit FDTD time-stepping
NASA Astrophysics Data System (ADS)
Tierens, W.
2016-12-01
Both partially implicit FDTD methods, and symplectic FDTD methods of high temporal accuracy (3rd or 4th order), are well documented in the literature. In this paper we combine them: we construct a conservative FDTD method which is fourth order accurate in time and is partially implicit. We show that the stability condition for this method depends exclusively on the explicit part, which makes it suitable for use in e.g. modelling wave propagation in plasmas.
Spatially explicit modeling in ecology: A review
DeAngelis, Donald L.; Yurek, Simeon
2017-01-01
The use of spatially explicit models (SEMs) in ecology has grown enormously in the past two decades. One major advancement has been that fine-scale details of landscapes, and of spatially dependent biological processes, such as dispersal and invasion, can now be simulated with great precision, due to improvements in computer technology. Many areas of modeling have shifted toward a focus on capturing these fine-scale details, to improve mechanistic understanding of ecosystems. However, spatially implicit models (SIMs) have played a dominant role in ecology, and arguments have been made that SIMs, which account for the effects of space without specifying spatial positions, have an advantage of being simpler and more broadly applicable, perhaps contributing more to understanding. We address this debate by comparing SEMs and SIMs in examples from the past few decades of modeling research. We argue that, although SIMs have been the dominant approach in the incorporation of space in theoretical ecology, SEMs have unique advantages for addressing pragmatic questions concerning species populations or communities in specific places, because local conditions, such as spatial heterogeneities, organism behaviors, and other contingencies, produce dynamics and patterns that usually cannot be incorporated into simpler SIMs. SEMs are also able to describe mechanisms at the local scale that can create amplifying positive feedbacks at that scale, creating emergent patterns at larger scales, and therefore are important to basic ecological theory. We review the use of SEMs at the level of populations, interacting populations, food webs, and ecosystems and argue that SEMs are not only essential in pragmatic issues, but must play a role in the understanding of causal relationships on landscapes.
Conformation of a Lennard-Jones polymer in explicit solvent
NASA Astrophysics Data System (ADS)
Ye, Yuting; Taylor, Mark
2012-04-01
The conformation of a polymer chain is solution is coupled to the local structure of the surrounding solvent and can undergo large changes in response to variations in solvent density and temperature. The many-body effects of solvent on the structure of an n-mer chain can be formally mapped to an exact n-body solvation potential. These potentials map the chain-solvent system to a single chain, thereby dramatically reducing the computational complexity of the polymer chain-in-solvent problem. We have recently shown that a pair-decomposition of this n-body potential is valid for short Lennard-Jones (LJ) chains in explicit LJ solvent [1]. Here we use these short chain results to construct solvation potentials for long chains. We present results for the size and intramolecular structure of LJ chains up to length n=400 in LJ solvent at state points spanning the solvent phase diagram (including vapor, liquid, and super-critical regions). In comparison with simulation results for the corresponding full chain-in-solvent system, our solvation potential approach is found to be quantitatively accurate for a wide range of solvent conditions and chain lengths.[4pt] [1] M.P. Taylor and S.R. Adhikari, J. Chem. Phys. 135, 044903 (2011).
Conformation of a Lennard-Jones polymer in explicit solvent
NASA Astrophysics Data System (ADS)
Ye, Yuting; Taylor, Mark
2011-10-01
The conformation of a polymer chain is solution is coupled to the local structure of the surrounding solvent and can undergo large changes in response to variations in solvent density and temperature. The many-body effects of solvent on the structure of an n-mer chain can be formally mapped to an exact n-body solvation potential. These potentials map the chain-solvent system to a single chain, thereby dramatically reducing the computational complexity of the polymer chain-in-solvent problem. We have recently shown that a pair-decomposition of this n-body potential is valid for short Lennard-Jones (LJ) chains in explicit LJ solvent [1]. Here we use these short chain results to construct solvation potentials for long chains. We present results for the size and intramolecular structure of LJ chains up to length n=400 in LJ solvent at state points spanning the solvent phase diagram (including vapor, liquid, and super-critical regions). In comparison with simulation results for the corresponding full chain-in-solvent system, our solvation potential approach is found to be quantitatively accurate for a wide range of solvent conditions and chain lengths.[4pt] [1] M.P. Taylor and S.R. Adhikari, J. Chem. Phys. 135, 044903 (2011).
An implicit-explicit flow solver for complex unsteady flows
NASA Astrophysics Data System (ADS)
Hsu, John Ming-Jey
2005-12-01
Current calculations of complex unsteady flows are prohibitively expensive for use in real engineering applications. Typical flow solvers for unsteady integration employ a fully implicit time stepping scheme, in which the equations are solved by an inner iteration. In order to achieve convergence within each physical time step, a substantial number of pseudo-time steps (typically between 30--100, depending on the case) are required. Another unfavorable characteristic of the dual time stepping method is that there are no available error estimates for time accuracy available unless the inner iterations are fully converged, although numerical experiments have demonstrated second order accuracy in time. The approach in this thesis is to construct hybrid type schemes by combining implicit and explicit schemes in a manner that guarantees second order accuracy in time. An initial time accurate ADI step is introduced, followed by a small number of cycles of the dual-time stepping scheme augmented by multigrid. The formal second order accuracy in time should be retained without the need for large numbers of inner iterations. The number of inner iterations required for convergence can thus be reduced while maintaining the same overall error levels. To investigate the effectiveness of the proposed scheme, several pitching airfoil test cases were examined, offering a close look at possible reductions in computational cost by adopting the present approach.
Li, Jing; Xu, Li; Yu, Qiong-Wei; Shi, Zhi-Guo; Zhang, Ting; Liu, Yan
2014-10-01
A portable sample preparation device with a magnetic polymer monolith as the extraction medium was constructed. The monolith was synthesized by polymerizing methacrylic acid and ethylene dimethacrylate around a cylindrical magnet. In this way, the monolith with a magnetic core could be readily attached to the extraction device by magnetism. The constructed device was evaluated for the enrichment of UV filters in water samples, followed by high-performance liquid chromatographic analysis. The extraction efficiency for the targets was satisfactory with no matrix interference. Good linearities were obtained for the UV filters with the correlation coefficients >0.9986. The limits of detection and quantification for the UV filters were 0.3-0.8 and 1.0-2.4 ng/mL, respectively. The recoveries of the UV filters from the spiked water samples at the concentration of 100 ng/mL were 95.3-101.7%, with relative standard deviations <10%. Accordingly, the proposed portable device was demonstrated to be suitable for on-site simultaneous sampling, purification, and preconcentration within a single step.
Permittivity of a magnetic fluid
Raikher, Yu.L.; Petrikevich, A.V.
1987-10-01
The authors mathematically investigate the statics and dynamics of the orientational polarization of a magnetic liquid subjected to the combined action of electric and magnetic fields. As the liquid model an ensemble of noninteracting magnetized ellipsoids made of ferrite distributed over the volume of a nonconducting liquid matrix was used. The ferrite particles forming the suspension were assumed to be single-domain and magnetically hard particles in the frozen moments approximation. Magnetic dipole and electric quadrupole moments are determined as is the permittivity tensor which, in stationary electric and magnetic fields, becomes biaxial. In a variable electric field the permittivity becomes an explicit function of time and frequency.
Global Auroral Energy Deposition Compared with Magnetic Indices
NASA Technical Reports Server (NTRS)
Brittnacher, M. J.; Fillingim, M. O.; Elsen, R.; Parks, G. K.; Germany, G. A.; Spann, J. F., Jr.
1997-01-01
Measurement of the global rate of energy deposition in the ionosphere via auroral particle precipitation is one of the primary goals of the Polar UVI program and is an important component of the ISTP program. The instantaneous rate of energy deposition for the entire month of January 1997 has been calculated by applying models to the UVI images and is presented by Fillingim et al. in this session. Magnetic indices, such as Kp, AE, and Dst, which are sensitive to variations in magnetospheric current systems have been constructed from ground magnetometer measurements and employed as measures of activity. The systematic study of global energy deposition raises the possibility of constructing a global magnetospheric activity index explicitly based on particle precipitation to supplement magnetic indices derived from ground magnetometer measurements. The relationship between global magnetic activity as measured by these indices and the rate of total global energy loss due to precipitation is not known at present. We study the correlation of the traditional magnetic index of Kp for the month of January 1997 with the energy deposition derived from the UVI images. We address the question of whether the energy deposition through particle precipitation generally matches the Kp and AE indices, or the more exciting, but distinct, possibility that this particle-derived index may provide an somewhat independent measure of global magnetospheric activity that could supplement traditional magnetically-based activity indices.
"Make It Explicit!": Improving Collaboration through Increase of Script Coercion
ERIC Educational Resources Information Center
Papadopoulos, P. M.; Demetriadis, S. N.; Weinberger, A.
2013-01-01
This paper investigates the impact of the proposed "Make It Explicit!" technique on students' learning when participating in scripted collaborative activities. The method posits that when asking students to proactively articulate their own positions explicitly, then improved peer interaction is triggered in a subsequent…
Measuring Explicit and Implicit Knowledge: A Psychometric Study in SLA
ERIC Educational Resources Information Center
Ebadi, Mandana Rohollahzadeh; Abedalaziz, Nabeel; Saad, Mohd Rashid Mohd
2015-01-01
Lack of valid means of measuring explicit and implicit knowledge in acquisition of second language is a concern issue in investigations of explicit and implicit learning. This paper endeavors to validate the use of four tests (i.e., Untimed Judgment Grammatical Test, UJGT; Test of Metalinguistic Knowledge, TMK; Elicited Oral Imitation Test, EOIT;…
Explicit Knowledge and Learning in SLA: A Cognitive Linguistics Perspective
ERIC Educational Resources Information Center
Roehr, Karen
2010-01-01
SLA researchers agree that explicit knowledge and learning play an important role in adult L2 development. In the field of cognitive linguistics, it has been proposed that implicit and explicit knowledge differ in terms of their internal category structure and the processing mechanisms that operate on their representation in the human mind. It has…
The Ms. Stereotype Revisited: Implicit and Explicit Facets
ERIC Educational Resources Information Center
Malcolmson, Kelly A.; Sinclair, Lisa
2007-01-01
Implicit and explicit stereotypes toward the title Ms. were examined. Participants read a short description of a target person whose title of address varied (Ms., Mrs., Miss, Mr.). They then rated the person on agentic and communal traits and completed an Implicit Association Test. Replicating earlier research (Dion, 1987), at an explicit level,…
Functional differences between statistical learning with and without explicit training
Reber, Paul J.; Paller, Ken A.
2015-01-01
Humans are capable of rapidly extracting regularities from environmental input, a process known as statistical learning. This type of learning typically occurs automatically, through passive exposure to environmental input. The presumed function of statistical learning is to optimize processing, allowing the brain to more accurately predict and prepare for incoming input. In this study, we ask whether the function of statistical learning may be enhanced through supplementary explicit training, in which underlying regularities are explicitly taught rather than simply abstracted through exposure. Learners were randomly assigned either to an explicit group or an implicit group. All learners were exposed to a continuous stream of repeating nonsense words. Prior to this implicit training, learners in the explicit group received supplementary explicit training on the nonsense words. Statistical learning was assessed through a speeded reaction-time (RT) task, which measured the extent to which learners used acquired statistical knowledge to optimize online processing. Both RTs and brain potentials revealed significant differences in online processing as a function of training condition. RTs showed a crossover interaction; responses in the explicit group were faster to predictable targets and marginally slower to less predictable targets relative to responses in the implicit group. P300 potentials to predictable targets were larger in the explicit group than in the implicit group, suggesting greater recruitment of controlled, effortful processes. Taken together, these results suggest that information abstracted through passive exposure during statistical learning may be processed more automatically and with less effort than information that is acquired explicitly. PMID:26472644
ERIC Educational Resources Information Center
Roehr-Brackin, Karen
2014-01-01
This article considers explicit knowledge and processes in second language (L2) learning from a usage-based theoretical perspective. It reports on the long-term development of a single instructed adult learner's use of two L2 constructions, the German Perfekt of "gehen" ("go," "walk") and "fahren"…
Magnetization of disclinated graphene in nonuniform magnetic field
NASA Astrophysics Data System (ADS)
Roshanzamir-Nikou, M.; Goudarzi, H.
2017-02-01
Two-dimensional disclinated atomic graphene layer in curved space-time is exactly discussed, and the explicit dependence of Landau levels on the topological defect and external magnetic field are obtained in the presence of nonuniform magnetic field. It is worth mentioning that the presence of topological defect reduces the degeneracy of energy levels. The persistent current, magnetization, susceptibility and the magnetoresistance of structure are investigated. It can be shown that the curvature of the conical surface affects the pattern of oscillations of persistent current and, of course, corresponding magnetoresistance. The behavior of the above physical quantities as a function of magnetic flux is explicitly found for various defects. We observe that increasing magnetic field leads to a aperiodic oscillation. The large Aharonov-Bohm flux gives rise to vanish the magnetization oscillations.
An explicit kinematic scenario for the Iapetus and Rheic Oceans
NASA Astrophysics Data System (ADS)
Domeier, Mat; Torsvik, Trond
2015-04-01
The opening of the Rheic Ocean by the rifting of Avalonia, and the subsequent closure of the Iapetus Ocean by means of the three-way continental collision between Laurentia, Baltica and Avalonia, together constitute the most dramatic, defining and well-studied tectonic events of the early Paleozoic. Despite this, modern kinematic models of those interrelated events are still schematic and/or spatiotemporally disjointed. This is in large part due to the fact that: 1.) many of the available models were originally built to explain a specific region (i.e. Northern Appalachians, Northern Ireland and Scotland, Norwegian Caledonides, etc.) and have only been expanded to neighboring regions as a speculative note, and 2.) the models were not constructed upon a rigorous plate tectonic framework, wherein plate boundaries are specified and the kinematics of the entire lithosphere within the domain are explicitly defined through time. Although the lithosphere of the Iapetus and Rheic Oceans was long ago destroyed, the kinematics of those basins can still be surmised through the careful consideration of paleomagnetic data from the continents and terranes formerly flanking those oceans, and from geological observables along their margins. It is thus possible to explore the tectonic evolution of those basins with kinematic models that strictly conform to plate tectonic rules, both in space and time. Such an approach can plainly identify existing kinematic concepts that are tectonically untenable and those that work only in isolation. Here we briefly elaborate on this approach and present the results of a developing full-plate model of the Iapetus and Rheic Oceans for Late Cambrian to end-Silurian time, with a particular focus on the development of the Caledonide margins.
Dream and Reality: Constructive Change Partners.
ERIC Educational Resources Information Center
Menge, Carleton P.
1982-01-01
Using William Blake's work, discusses the element of the ideal in the development of contemporary adolescents. Discusses a model of constructive change in which explicit future outcomes are used as a starting point to construct new skills needed for change. Describes a monitoring system to measure progress. (RC)
NASA Astrophysics Data System (ADS)
Ou, Jinzhao; Mei, Mingliang; Xu, Xinxin
2016-06-01
A magnetic polyoxometalates based adsorbent has been synthesized successfully through the loading of amino functionalized Fe3O4 (NH2-Fe3O4) on nanoparticle of a coordination complex modified polyoxometalates (CC/POMNP). FTIR illustrate there exist intense hydrogen bonds between NH2-Fe3O4 and CC/POMNP, which keep the stability of this adsorbent. At room temperature, this adsorbent exhibits ferromagnetic character with saturation magnetization of 8.19 emu g-1, which provides prerequisite for fast magnetic separation. Water treatment experiment illustrates this POM based magnetic adsorbent exhibits high adsorption capacity on tetracycline. The adsorption process can be described well with Temkin model, which illustrates the interaction between adsorbent and tetracycline plays the dominated role in tetracycline removal. The rapid, high efficient tetracycline adsorption ability suggests this POM based magnetic adsorbent exhibits promising prospect in medical and agriculture waste water purification. A magnetic polyoxometalates based adsorbent, which exhibits excellent tetracycline adsorption removal property has been synthesized through the loading of NH2-Fe3O4 on coordination complex modified polyoxometalates
The effect of explicit financial incentives on physician behavior.
Armour, B S; Pitts, M M; Maclean, R; Cangialose, C; Kishel, M; Imai, H; Etchason, J
2001-05-28
Managed care organizations use explicit financial incentives to influence physicians' use of resources. This has contributed to concerns regarding conflicts of interest for physicians and adverse effects on the quality of patient care. In light of recent publicized legislative and legal battles about this issue, we reviewed the literature and analyzed studies that examine the effect of these explicit financial incentives on the behavior of physicians. The method used to undertake the literature review followed the approach set forth in the Cochrane Collaboration handbook. Our literature review revealed a paucity of data on the effect of explicit financial incentives. Based on this limited evidence, explicit incentives that place individual physicians at financial risk appear to be effective in reducing physician resource use. However, the empirical evidence regarding the effectiveness of bonus payments on physician resource use is mixed. Similarly, our review revealed mixed effects of the influence of explicit financial incentives on the quality of patient care. The effect of explicit financial incentives on physician behavior is complicated by a lack of understanding of the incentive structure by the managed care organization and the physician. The lack of a universally acceptable definition of quality renders it important that future researchers identify the term explicitly.
Disentangling Rheumatoid Arthritis Patients’ Implicit and Explicit Attitudes toward Methotrexate
Linn, Annemiek J.; Vandeberg, Lisa; Wennekers, Annemarie M.; Vervloet, Marcia; van Dijk, Liset; van den Bemt, Bart J. F.
2016-01-01
Medication non-adherence is a major public health problem that has been termed an ‘invisible epidemic.’ Non-adherence is not only associated with negative clinical consequences but can also result in substantial healthcare costs. Up to now, effective adherence interventions are scarce and a more comprehensive model of adherence determinants is required to target the determinants for not taking the medication as prescribed. Current approaches only included explicit attitudes such as self-reported evaluations of medication as determinants, neglecting the role of associative processes that shape implicit attitudes. Implicit processes can predict daily behavior more accurately than explicit attitudes. Our aim is to assess explicit and implicit attitudes toward medication and explore the relation with beliefs, adherence and clinical (laboratory) outcomes in chronically ill patients. Fifty two Rheumatic Arthritis (RA) patients’ attitudes toward Methotrexate (MTX) were explicitly (self-reported) and implicitly (Single-Category Implicit Association Test) assessed and related to the Beliefs about Medicine Questionnaire, the Compliance Questionnaire on Rheumatology and laboratory parameters [Erythrocyte Sedimentation Rate (ESR), C-Reactive Protein (CRP)]. Results show that explicit attitudes were positive and health-related. Implicit attitudes were, however, negative and sickness-related. Half of the patients displayed explicitly positive but implicitly negative attitudes. Explicit attitudes were positively related to ESR. A positive relationship between implicit attitudes and disease duration was observed. In this study, we have obtained evidence suggesting that the measurement of implicit attitudes and associations provides different information than explicit, self-reported attitudes toward medication. Since patients’ implicit attitudes deviated from explicit attitudes, we can conclude that the relationship between implicit attitudes and medication adherence is
NASA Astrophysics Data System (ADS)
Buchachenko, A. L.
2009-10-01
An analysis of magnetism of nanochemical systems opens up new ways to creating ferromagnets from diamagnetic substances and new principles for constructing molecular ferromagnets, hybrid magnetic materials, and monomolecular magnets on the basis of high-spin molecules and complexes. Their use in spin computing is considered.
Fischer, G.E.
1985-07-01
These two lectures on iron dominated magnets are meant for the student of accelerator science and contain general treatments of the subjects design and construction. The material is arranged in the categories: General Concepts and Cost Considerations, Profile Configuration and Harmonics, Magnetic Measurements, a few examples of ''special magnets'' and Materials and Practices. Extensive literature is provided.
Bridging implicit and explicit solvent approaches for membrane electrostatics.
Lin, Jung-Hsin; Baker, Nathan A; McCammon, J Andrew
2002-01-01
Conformations of a zwitterionic bilayer were sampled from a molecular dynamics simulation and their electrostatic properties analyzed by solution of the Poisson equation. These traditionally implicit electrostatic calculations were performed in the presence of varying amounts of explicit solvent to assess the magnitude of error introduced by a uniform dielectric description of water surrounding the bilayer. It was observed that membrane dipole potential calculations in the presence of explicit water were significantly different than wholly implicit solvent calculations with the calculated dipole potential converging to a reasonable value when four or more hydration layers were included explicitly. PMID:12202363
Moderators of the Relationship between Implicit and Explicit Evaluation
Nosek, Brian A.
2005-01-01
Automatic and controlled modes of evaluation sometimes provide conflicting reports of the quality of social objects. This paper presents evidence for four moderators of the relationship between automatic (implicit) and controlled (explicit) evaluations. Implicit and explicit preferences were measured for a variety of object pairs using a large sample. The average correlation was r = .36, and 52 of the 57 object pairs showed a significant positive correlation. Results of multilevel modeling analyses suggested that: (a) implicit and explicit preferences are related, (b) the relationship varies as a function of the objects assessed, and (c) at least four variables moderate the relationship – self-presentation, evaluative strength, dimensionality, and distinctiveness. The variables moderated implicit-explicit correspondence across individuals and accounted for much of the observed variation across content domains. The resulting model of the relationship between automatic and controlled evaluative processes is grounded in personal experience with the targets of evaluation. PMID:16316292
Implicit and explicit learning in individuals with agrammatic aphasia.
Schuchard, Julia; Thompson, Cynthia K
2014-06-01
Implicit learning is a process of acquiring knowledge that occurs without conscious awareness of learning, whereas explicit learning involves the use of overt strategies. To date, research related to implicit learning following stroke has been largely restricted to the motor domain and has rarely addressed implications for language. The present study investigated implicit and explicit learning of an auditory word sequence in 10 individuals with stroke-induced agrammatic aphasia and 18 healthy age-matched participants using an adaptation of the Serial Reaction Time task. Individuals with aphasia showed significant learning under implicit, but not explicit, conditions, whereas age-matched participants learned under both conditions. These results suggest significant implicit learning ability in agrammatic aphasia. Furthermore, results of an auditory sentence span task indicated working memory deficits in individuals with agrammatic aphasia, which are discussed in relation to explicit and implicit learning processes.
Multidimensional explicit difference schemes for hyperbolic conservation laws
NASA Technical Reports Server (NTRS)
Van Leer, B.
1984-01-01
First- and second-order explicit difference schemes are derived for a three-dimensional hyperbolic system of conservation laws, without recourse to dimensional factorization. All schemes are upwind biased and optimally stable.
Multidimensional explicit difference schemes for hyperbolic conservation laws
NASA Technical Reports Server (NTRS)
Vanleer, B.
1983-01-01
First and second order explicit difference schemes are derived for a three dimensional hyperbolic system of conservation laws, without recourse to dimensional factorization. All schemes are upwind (backward) biased and optimally stable.
Implicit and explicit representations of hand position in tool use.
Rand, Miya K; Heuer, Herbert
2013-01-01
Understanding the interactions of visual and proprioceptive information in tool use is important as it is the basis for learning of the tool's kinematic transformation and thus skilled performance. This study investigated how the CNS combines seen cursor positions and felt hand positions under a visuo-motor rotation paradigm. Young and older adult participants performed aiming movements on a digitizer while looking at rotated visual feedback on a monitor. After each movement, they judged either the proprioceptively sensed hand direction or the visually sensed cursor direction. We identified asymmetric mutual biases with a strong visual dominance. Furthermore, we found a number of differences between explicit and implicit judgments of hand directions. The explicit judgments had considerably larger variability than the implicit judgments. The bias toward the cursor direction for the explicit judgments was about twice as strong as for the implicit judgments. The individual biases of explicit and implicit judgments were uncorrelated. Biases of these judgments exhibited opposite sequential effects. Moreover, age-related changes were also different between these judgments. The judgment variability was decreased and the bias toward the cursor direction was increased with increasing age only for the explicit judgments. These results indicate distinct explicit and implicit neural representations of hand direction, similar to the notion of distinct visual systems.
Spatial working memory interferes with explicit, but not probabilistic cuing of spatial attention.
Won, Bo-Yeong; Jiang, Yuhong V
2015-05-01
Recent empirical and theoretical work has depicted a close relationship between visual attention and visual working memory. For example, rehearsal in spatial working memory depends on spatial attention, whereas adding a secondary spatial working memory task impairs attentional deployment in visual search. These findings have led to the proposal that working memory is attention directed toward internal representations. Here, we show that the close relationship between these 2 constructs is limited to some but not all forms of spatial attention. In 5 experiments, participants held color arrays, dot locations, or a sequence of dots in working memory. During the memory retention interval, they performed a T-among-L visual search task. Crucially, the probable target location was cued either implicitly through location probability learning or explicitly with a central arrow or verbal instruction. Our results showed that whereas imposing a visual working memory load diminished the effectiveness of explicit cuing, it did not interfere with probability cuing. We conclude that spatial working memory shares similar mechanisms with explicit, goal-driven attention but is dissociated from implicitly learned attention.
these systems can improve water quality, engineers and scientists construct systems that replicate the functions of natural wetlands. Constructed wetlands are treatment systems that use natural processes
Explicit argumentation instruction to facilitate conceptual understanding and argumentation skills
NASA Astrophysics Data System (ADS)
Seda Cetin, Pinar
2014-01-01
Background: Argumentation is accepted by many science educators as a major component of science education. Many studies have investigated students' conceptual understanding and their engagement in argumentative activities. However, studies conducted in the subject of chemistry are very rare. Purpose: The present study aimed to investigate the effects of argumentation-based chemistry lessons on pre-service science teachers' understanding of reaction rate concepts, their quality of argumentation, and their consideration of specific reaction rate concepts in constructing an argument. Moreover, students' perceptions of argumentation lessons were explored. Sample: There were 116 participants (21 male and 95 female), who were pre-service first-grade science teachers from a public university. The participants were recruited from the two intact classes of a General Chemistry II course, both of which were taught by the same instructor. Design and methods: In the present study, non-equivalent control group design was used as a part of quasi-experimental design. The experimental group was taught using explicit argumentation activities, and the control group was instructed using traditional instruction. The data were collected using a reaction rate concept test, a pre-service teachers' survey, and the participants' perceptions of the argumentation lessons questionnaire. For the data analysis, the Wilcoxon Signed Rank Test, the Mann-Whitney U-test and qualitative techniques were used. Results: The results of the study indicated that an argumentation-based intervention caused significantly better acquisition of scientific reaction rate-related concepts and positively impacted the structure and complexity of pre-service teachers' argumentation. Moreover, the majority of the participants reported positive feelings toward argumentation activities. Conclusions: As students are encouraged to state and support their view in the chemistry classroom when studying reaction rate, it was
Exact soliton solution of spin chain with an external magnetic field in linear wave background
NASA Astrophysics Data System (ADS)
Li, Qiu-Yan; Xie, Zheng-Wei; Li, Lu; Li, Zai-Dong; Liang, Jiu-Qing
2004-07-01
Employing a simple, straightforward Darboux transformation we construct exact N-soliton solution for anisotropic spin chain driven by an external magnetic field in linear wave background. As a special case the explicit one- and two-soliton solution dressed by the linear wave corresponding to magnon in quantum theory is obtained analytically and its property is discussed in detail. The dispersion law, effective soliton mass, and the energy of each soliton are investigated as well. Our result show that the stability criterion of soliton is related with anisotropic parameter and the amplitude of the linear wave.
Wang, Bo; Prastawa, Marcel; Awate, Suyash P; Irimia, Andrei; Chambers, Micah C; Vespa, Paul M; van Horn, John D; Gerig, Guido
2012-01-01
Traumatic brain injury (TBI) due to falls, car accidents, and warfare affects millions of people annually. Determining personalized therapy and assessment of treatment efficacy can substantially benefit from longitudinal (4D) magnetic resonance imaging (MRI). In this paper, we propose a method for segmenting longitudinal brain MR images with TBI using personalized atlas construction. Longitudinal images with TBI typically present topological changes over time due to the effect of the impact force on tissue, skull, and blood vessels and the recovery process. We address this issue by defining a novel atlas construction scheme that explicitly models the effect of topological changes. Our method automatically estimates the probability of topological changes jointly with the personalized atlas. We demonstrate the effectiveness of this approach on MR images with TBI that also have been segmented by human raters, where our method that integrates 4D information yields improved validation measures compared to temporally independent segmentations.
NASA Astrophysics Data System (ADS)
Dabaghi, Azizollah
The study investigated the effects of correction of learners` grammatical errors on acquisition. Specifically, it compared the effects of manner of correction (explicit versus implicit correction). It also investigated the relative effects of explicit and implicit correction of morphological versus syntactic features and correction of developmental early versus developmental late features. Data were collected from 56 intermediate level Iranian students of English Each participant was required to read and then retell a written text in their own words during an oral interview. During or following the interview the researcher corrected the participants on their grammatical errors implicitly (using recasts) or explicitly. Individualised tests focusing on the corrected errors were constructed and administered. Statistical analyses were conducted on the scores the participants received on their individualised tests. Results showed that the participants who received explicit correction gained significantly higher scores than those who received implicit correction. Analyses of the interactions between independent variables showed that explicit correction was more effective for the acquisition of developmental early features and implicit correction was more effective for the acquisition of developmental late features.
NASA Technical Reports Server (NTRS)
Nishida, J. M.
1975-01-01
An analytical and experimental program to demonstrate the technical feasibility of a lightweight, high-efficiency, 1-2 kW cw, permanent magnet focused klystron operating at 12.0 GHz was described. The design is based on use of a samarium-cobalt permanent magnet for focusing of the electron beam and choice of the most optimum parameters for maximum efficiency. A filter-loaded output circuit is used for the required bandwidth. The design incorporates a collector which is demountable from the tube to facilitate multistage depressed collector experiments, permitting replacement with a NASA-designed axisymmetric, electrostatic collector for linear beam microwave tubes. A further requirement is that the focusing field between the last interaction gap and the collector decay in a prescribed manner referred to as adiabatic expansion.
Factors influencing university students' explicit and implicit sexual double standards.
Sakaluk, John K; Milhausen, Robin R
2012-01-01
Quantitative research has resulted in inconsistent evidence for the existence of a sexual double standard, leading Crawford and Popp ( 2003 ) to issue a call for methodological innovation. The implicit association test (IAT; Greenwald, McGhee, & Schwartz, 1998 ) is a measure that may provide a means to examine the double standard without the contamination of the demand characteristics and social desirability biases that plague self-report research (Marks & Fraley, 2005 ). The purpose of this study was to examine the factors influencing explicit and implicit double standards, and to examine the relationship between these explicit and implicit double standards, and levels of socially desirable responding. One hundred and three university students completed a sexual double standard IAT, an explicit measure of the double standard, and measures of socially desirable responding. Hierarchical regression analysis indicated that levels of socially desirable responding were not related to implicit or explicit double standards. Men endorsed a stronger explicit traditional double standard than women, whereas for implicit sexual standards, men demonstrated a relatively gender-neutral evaluation and women demonstrated a strong reverse double standard. These results suggest the existence of a complex double standard, and indicate that more research of sexual attitudes should include implicit measures.
1987-08-01
solution of the Korteweg-de Vries equation ( KdV ), working our way up to the derivation of the multi-soliton solution of the sine-Gordon equation (sG...SOLITARY WAVE SOLUTIONS OF NONLINEAR PARTIAL DIFFERENTIAL EQUATIONS j DiS~~Uj~l. _’UDistribution/Willy Hereman AvaiiLi -itY Codes Technical Summary Report...Key Words: soliton theory, solitary waves, coupled KdV , evolution equations , direct methods, Harry Dym, sine-Gordon Mathematics Department, University
Zhu, Wen-Hua; Li, Shan; Gao, Chen; Xiong, Xia; Zhang, Yan; Liu, Li; Powell, Annie K; Gao, Song
2016-03-21
Two series of lanthanide dinuclear complexes with the general formulae, [Ln(n-PNO)(Bza)3(H2O)] {Bza = benzoic acid; n = 3, n-PNO = 3-picoline N-oxide, Dy(1) and Er(2); and n = 4, n-PNO = 4-picoline N-oxide, Nd(3), Eu(4), Gd(5), Tb(6), Dy(7), Er(8) and Y(9)} have been successfully synthesized by the hydrothermal method. Single-crystal X-ray diffraction experiments illustrate that the two series of compounds possess similar carboxylic ligand-bridged dinuclear structure and coordination geometry around the lanthanide ions despite the different methyl-substituent positions on the neutral ligand. Comparative studies of the Dy analogues in the static-field measurements reveal only a little difference with a small butterfly-shaped opening for complex 1 and a close hysteresis loop for 7 at 2.0 K. However, systematic investigations of the alternating-current (ac) measurements indicate that the different substituent positions of the picoline N-oxide ligand have a significant effect on the magnetic relaxation dynamics. A more substantial suppression of the quantum tunnelling of magnetization (QTM) effect and pronounced slow magnetic relaxation were observed in complex 7 as compared to 1 under both zero and a 1 kOe static field.
Ding, Yongling; Shen, Shirley Z; Sun, Huadong; Sun, Kangning; Liu, Futian; Qi, Yushi; Yan, Jun
2015-03-01
In this study, a novel hydrogel, chitosan (CS) crosslinked carboxymethyl-β-cyclodextrin (CM-β-CD) polymer modified Fe3O4 magnetic nanoparticles was synthesized for delivering hydrophobic anticancer drug 5-fluorouracil (CS-CDpoly-MNPs). Carboxymethyl-β-cyclodextrin being grafted on the Fe3O4 nanoparticles (CDpoly-MNPs) contributed to an enhancement of adsorption capacities because of the inclusion abilities of its hydrophobic cavity with insoluble anticancer drugs through host-guest interactions. Experimental results indicated that the amounts of crosslinking agent and bonding times played a crucial role in determining morphology features of the hybrid nanocarriers. The nanocarriers exhibited a high loading efficiency (44.7±1.8%) with a high saturation magnetization of 43.8emu/g. UV-Vis spectroscopy results showed that anticancer drug 5-fluorouracil (5-Fu) could be successfully included into the cavities of the covalently linked CDpoly-MNPs. Moreover, the free carboxymethyl groups could enhance the bonding interactions between the covalently linked CDpoly-MNPs and anticancer drugs. In vitro release studies revealed that the release behaviors of CS-CDpoly-MNPs carriers were pH dependent and demonstrated a swelling and diffusion controlled release. A lower pH value led to swelling effect and electrostatic repulsion contributing to the protonation amine impact of NH3(+), and thus resulted in a higher release rate of 5-Fu. The mechanism of 5-Fu encapsulated into the magnetic chitosan nanoparticles was tentatively proposed.
NASA Technical Reports Server (NTRS)
1985-01-01
Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.
Multifunctionality in molecular magnetism.
Pinkowicz, Dawid; Czarnecki, Bernard; Reczyński, Mateusz; Arczyński, Mirosław
2015-01-01
Molecular magnetism draws from the fundamental ideas of structural chemistry and combines them with experimental physics resulting in one of the highest profile current topics, namely molecular materials that exhibit multifunctionality. Recent advances in the design of new generations of multifunctional molecular magnets that retain the functions of the building blocks and exhibit non-trivial magnetic properties at higher temperatures provide promising evidence that they may be useful for the future construction of nanoscale devices. This article is not a complete review but is rather an introduction into thefascinating world of multifunctional solids with magnetism as the leitmotif. We provide a subjective selection and discussion of the most inspiring examples of multifunctional molecular magnets: magnetic sponges, guest-responsive magnets, molecular magnets with ionic conductivity, photomagnets and non-centrosymmetric and chiral magnets.
Mueller, Fred M.; Bronisz, Lawrence; Grube, Holger; Nelson, David C.; Mace, Jonathan L.
2006-11-14
A magnetic infrasound sensor is produced by constraining a permanent magnet inside a magnetic potential well above the surface of superconducting material. The magnetic infrasound sensor measures the position or movement of the permanent magnet within the magnetic potential well, and interprets the measurements. Infrasound sources can be located and characterized by combining the measurements from one or more infrasound sensors. The magnetic infrasound sensor can be tuned to match infrasound source types, resulting in better signal-to-noise ratio. The present invention can operate in frequency modulation mode to improve sensitivity and signal-to-noise ratio. In an alternate construction, the superconductor can be levitated over a magnet or magnets. The system can also be driven, so that time resolved perturbations are sensed, resulting in a frequency modulation version with improved sensitivity and signal-to-noise ratio.
Explicit infiltration equations and the Lambert W-function
NASA Astrophysics Data System (ADS)
Parlange, J.-Y.; Barry, D. A.; Haverkamp, R.
The Green and Ampt infiltration formula, as well as the Talsma and Parlange formula, are two-parameter equations that are both expressible in terms of Lambert W-functions. These representations are used to derive explicit, simple and accurate approximations for each case. The two infiltration formulas are limiting cases that can be deduced from an existing three-parameter infiltration equation, the third parameter allowing for interpolation between the limiting cases. Besides the limiting cases, there is another case for which the three-parameter infiltration equation yields an exact solution. The three-parameter equation can be solved by fixed-point iteration, a scheme which can be exploited to obtain a sequence of increasingly complex explicit infiltration equations. For routine use, a simple, explicit approximation to the three-parameter infiltration equation is derived. This approximation eliminates the need to iterate for most practical circumstances.
The time course of explicit and implicit categorization.
Smith, J David; Zakrzewski, Alexandria C; Herberger, Eric R; Boomer, Joseph; Roeder, Jessica L; Ashby, F Gregory; Church, Barbara A
2015-10-01
Contemporary theory in cognitive neuroscience distinguishes, among the processes and utilities that serve categorization, explicit and implicit systems of category learning that learn, respectively, category rules by active hypothesis testing or adaptive behaviors by association and reinforcement. Little is known about the time course of categorization within these systems. Accordingly, the present experiments contrasted tasks that fostered explicit categorization (because they had a one-dimensional, rule-based solution) or implicit categorization (because they had a two-dimensional, information-integration solution). In Experiment 1, participants learned categories under unspeeded or speeded conditions. In Experiment 2, they applied previously trained category knowledge under unspeeded or speeded conditions. Speeded conditions selectively impaired implicit category learning and implicit mature categorization. These results illuminate the processing dynamics of explicit/implicit categorization.
Lie Symmetries, Conservation Laws and Explicit Solutions for Time Fractional Rosenau–Haynam Equation
NASA Astrophysics Data System (ADS)
Qin, Chun-Yan; Tian, Shou-Fu; Wang, Xiu-Bin; Zhang, Tian-Tian
2017-02-01
Under investigation in this paper is the invariance properties of the time fractional Rosenau-Haynam equation, which can be used to describe the formation of patterns in liquid drops. By using the Lie group analysis method, the vector fields and symmetry reductions of the equation are derived, respectively. Moreover, based on the power series theory, a kind of explicit power series solutions for the equation are well constructed with a detailed derivation. Finally, by using the new conservation theorem, two kinds of conservation laws of the equation are well constructed with a detailed derivation. Supported by the Fundamental Research Fund for Talents Cultivation Project of the China University of Mining and Technology under Grant No. YC150003
Tepordei, V.V.
1995-01-01
Part of the 1994 Industrial Minerals Review. The production, consumption, and applications of construction aggregates are reviewed. In 1994, the production of construction aggregates, which includes crushed stone and construction sand and gravel combined, increased 7.7 percent to 2.14 Gt compared with the previous year. These record production levels are mostly a result of funding for highway construction work provided by the Intermodal Surface Transportation Efficiency Act of 1991. Demand is expected to increase for construction aggregates in 1995.
Accurate thermochemistry from explicitly correlated distinguishable cluster approximation.
Kats, Daniel; Kreplin, David; Werner, Hans-Joachim; Manby, Frederick R
2015-02-14
An explicitly correlated version of the distinguishable-cluster approximation is presented and extensively benchmarked. It is shown that the usual F12-type explicitly correlated approaches are applicable to distinguishable-cluster theory with single and double excitations, and the results show a significant improvement compared to coupled-cluster theory with singles and doubles for closed and open-shell systems. The resulting method can be applied in a black-box manner to systems with single- and multireference character. Most noticeably, optimized geometries are of coupled-cluster singles and doubles with perturbative triples quality or even better.
Comment on ``Analysis of optimal velocity model with explicit delay''
NASA Astrophysics Data System (ADS)
Davis, L. C.
2002-09-01
The effect of including an explicit delay time (due to driver reaction) on the optimal velocity model is studied. For a platoon of vehicles to avoid collisions, many-vehicle simulations demonstrate that delay times must be well below the critical delay time determined by a linear analysis for the response of a single vehicle. Safe platoons require rather small delay times, substantially smaller than typical reaction times of drivers. The present results do not support the conclusion of Bando et al. [M. Bando, K. Hasebe, K. Nakanishi, and A. Nakayama, Phys. Rev. E 58, 5429 (1998)] that explicit delay plays no essential role.
Comment on "Analysis of optimal velocity model with explicit delay".
Davis, L C
2002-09-01
The effect of including an explicit delay time (due to driver reaction) on the optimal velocity model is studied. For a platoon of vehicles to avoid collisions, many-vehicle simulations demonstrate that delay times must be well below the critical delay time determined by a linear analysis for the response of a single vehicle. Safe platoons require rather small delay times, substantially smaller than typical reaction times of drivers. The present results do not support the conclusion of Bando et al. [M. Bando, K. Hasebe, K. Nakanishi, and A. Nakayama, Phys. Rev. E 58, 5429 (1998)] that explicit delay plays no essential role.
Explicit solution for Raman fiber laser using Lambert W function.
Huang, Chaohong; Cai, Zhiping; Ye, Chenchun; Xu, Huiying
2007-04-16
In this paper, an approximate explicit solution for the first-order Raman fiber laser is obtained by using Lambert W function. Good agreement between the explicit solution and numerical simulation is demonstrated. Furthermore, the optimal design of Raman fiber laser is discussed using the proposed solution. The optimal values of fiber length, reflectivity of output fiber Bragg grating and power transfer efficiency are obtained under different pump power. There exists a certain tolerance of the optimal parameters, in which the output power decreases only slightly. The optimal fiber length and reflectivity of output FBG decrease with increasing pump power.
Explicit solution for Raman fiber laser using Lambert W function
NASA Astrophysics Data System (ADS)
Huang, Chaohong; Cai, Zhiping; Ye, Chenchun; Xu, Huiying
2007-04-01
In this paper, an approximate explicit solution for the first-order Raman fiber laser is obtained by using Lambert W function. Good agreement between the explicit solution and numerical simulation is demonstrated. Furthermore, the optimal design of Raman fiber laser is discussed using the proposed solution. The optimal values of fiber length, reflectivity of output fiber Bragg grating and power transfer efficiency are obtained under different pump power. There exists a certain tolerance of the optimal parameters, in which the output power decreases only slightly. The optimal fiber length and reflectivity of output FBG decrease with increasing pump power.
Common molecular mechanisms in explicit and implicit memory.
Barco, Angel; Bailey, Craig H; Kandel, Eric R
2006-06-01
Cellular and molecular studies of both implicit and explicit memory suggest that experience-dependent modulation of synaptic strength and structure is a fundamental mechanism by which these memories are encoded and stored within the brain. In this review, we focus on recent advances in our understanding of two types of memory storage: (i) sensitization in Aplysia, a simple form of implicit memory, and (ii) formation of explicit spatial memories in the mouse hippocampus. These two processes share common molecular mechanisms that have been highly conserved through evolution.
Modeling ductile dynamic fracture with ABAQUS/explicit
Anderson, C.A.; Turner, C.
1996-05-01
This paper illustrates the use of advanced constitutive models in ABAQUS/Explicit together with highly focused finite element meshes to simulate the propagation of a fracture in a ductile medium. A double edge-cracked specimen under far field dynamic tensile loading is analyzed, and shows both rectilinear motion or unstable oscillatory motion of the crack depending on the material property constraints. Results are also presented for a simulation of ASTM`s standard fracture test E399. Comparisons of ABAQUS/Explicit results with experiments or other analytical/numerical results are made.
Liu, Cai-Ming; Zhang, De-Qing; Zhu, Dao-Ben
2016-04-04
A novel 3D MOF based on dysprosium(iii) oxalate and 1,10-phenanthroline (phen), {[Dy(C2O4)1.5phen]·0.5H2O}n (1), has been hydrothermally synthesized. The Dy(3+) ion acts as a typical Y-shaped node, linking to each other to generate an interesting 3D topology structure. Complex 1 is the first 3D DyMOF displaying both ferromagnetic coupling and field-induced two-step magnetic relaxation.
NASA Astrophysics Data System (ADS)
Drake, Bruce D.; Dunbar, Michael T.; Smith, Richard L., Jr.
1990-09-01
A simple new design for a high-pressure magnetic pump is described. The pump requires minimal machining, requires no lubricant or seals, and uses no special alloys, resins or polymer components, internally. The pump described could circulate supercritical carbon dioxide and methanol mixtures satisfactorily and could achieve pumping rates of 200-cm3/min water at atmospheric pressure and 30-cm water head. The pump is assembled primarily from commercially available parts at a total 1989 cost of approximately 300 plus the cost of the motor and drive.
Moon, Chung-Man; Jeong, Gwang-Woo
2017-03-01
Background The neuroanatomical abnormalities associated with behavioral dysfunction on explicit memory in patients generalized anxiety disorder (GAD) have not yet been clearly identified. Purpose To investigate the regional gray matter (GM) and white matter (WM) volume alterations over the whole brain in patients with GAD, as well as the correlation between the brain structural abnormality and explicit memory dysfunction. Material and Methods Twenty patients with GAD and 20 healthy controls matched for age, sex, and education level underwent high-resolution T1-weighted magnetic resonance imaging (MRI). The participants performed the explicit memory tasks with the neutral and anxiety-inducing words. Results Patients with GAD showed significantly reduced GM volumes in the midbrain (MB), thalamus, hippocampus (Hip), insula, and superior temporal gyrus (STG); and reduced WM volumes in the MB, anterior limb of the internal capsule (ALIC), dorsolateral prefrontal cortex (DLPFC), and precentral gyrus (PrG). It is important to note that the GM volume of the Hip and the WM volume of the DLPFC were positively correlated with the recognition accuracy (%) in the explicit memory tasks with neutral and anxiety-inducing words, respectively. On the other hand, the WM volume of the PrG was negatively correlated with the reaction time in the same memory tasks. Conclusion This study demonstrated the regional volume changes on whole-brain GM and WM and the correlation between the brain structural alteration and explicit memory dysfunction in GAD patients. These findings would be helpful to understand the association between the brain structure abnormality and the functional deficit in the explicit memory in GAD.
Mu, Xiaoyu; Qiao, Juan; Qi, Li; Liu, Ying; Ma, Huimin
2014-08-13
Developing facile and high-throughput methods for exploring pharmacological inhibitors of D-amino acid oxidase (DAAO) has triggered increasing interest. In this work, DAAO was immobilized on the magnetic nanoparticles, which were modified by a biocompatible reactive polymer, poly(glycidyl methacrylate) (PGMA) via an atom transfer radical polymerization technique. Interestingly, the enzyme immobilization process was greatly promoted with the assistance of a lithium perchlorate catalyst. Meanwhile, a new amino acid ionic liquid (AAIL) was successfully synthesized and employed as the efficient chiral ligand in a chiral ligand exchange capillary electrophoresis (CLE-CE) system for chiral separation of amino acids (AAs) and quantitation of methionine, which was selected as the substrate of DAAO. Then, the apparent Michaelis-Menten constants in the enzyme system were determined with the proposed CLE-CE method. The prepared DAAO-PGMA-Fe3O4 nanoparticles exhibited excellent reusability and good stability. Moreover, the enzyme reactor was successfully applied in screening DAAO inhibitors. These results demonstrated that the enzyme could be efficiently immobilized on the polymer-grafted magnetic nanoparticles and that the obtained enzyme reactor has great potential in screening enzyme inhibitors, further offering new insight into monitoring the relevant diseases.
Construction of an alternating gradient magnetometer
NASA Technical Reports Server (NTRS)
Garland, Michael M.
1988-01-01
A magnetometer is described which was constructed to facilitate the study and characterization of the magnetic properties of high transition temperature superconductors. This instrument was used to measure the dc magnetic susceptibility of several superconducting compounds as a function of temperature. The construction of the magnetometer and the operating parameters are discussed in detail.
Being Explicit about Modeling: A First Person Study in India
ERIC Educational Resources Information Center
Setty, Rohit Boggarm
2013-01-01
In this dissertation, I examine the work involved in teacher educator modeling. In particular, the study is concerned with modeling that aims to explicitly make teaching practices visible, learnable, and that does so in particularly demonstrative ways. One form of this type of modeling is what I term "dialogic modeling." The study…
Explicit versus Implicit Social Cognition Testing in Autism Spectrum Disorder
ERIC Educational Resources Information Center
Callenmark, Björn; Kjellin, Lars; Rönnqvist, Louise; Bölte, Sven
2014-01-01
Although autism spectrum disorder is defined by reciprocal social-communication impairments, several studies have found no evidence for altered social cognition test performance. This study examined explicit (i.e. prompted) and implicit (i.e. spontaneous) variants of social cognition testing in autism spectrum disorder. A sample of 19 adolescents…
Effect of explicit dimension instruction on speech category learning
Chandrasekaran, Bharath; Yi, Han-Gyol; Smayda, Kirsten E.; Maddox, W. Todd
2015-01-01
Learning non-native speech categories is often considered a challenging task in adulthood. This difficulty is driven by cross-language differences in weighting critical auditory dimensions that differentiate speech categories. For example, previous studies have shown that differentiating Mandarin tonal categories requires attending to dimensions related to pitch height and direction. Relative to native speakers of Mandarin, the pitch direction dimension is under-weighted by native English speakers. In the current study, we examined the effect of explicit instructions (dimension instruction) on native English speakers' Mandarin tone category learning within the framework of a dual-learning systems (DLS) model. This model predicts that successful speech category learning is initially mediated by an explicit, reflective learning system that frequently utilizes unidimensional rules, with an eventual switch to a more implicit, reflexive learning system that utilizes multidimensional rules. Participants were explicitly instructed to focus and/or ignore the pitch height dimension, the pitch direction dimension, or were given no explicit prime. Our results show that instruction instructing participants to focus on pitch direction, and instruction diverting attention away from pitch height resulted in enhanced tone categorization. Computational modeling of participant responses suggested that instruction related to pitch direction led to faster and more frequent use of multidimensional reflexive strategies, and enhanced perceptual selectivity along the previously underweighted pitch direction dimension. PMID:26542400
Flexibles Grouping, Explicit Reading Instruction in Elementary School
ERIC Educational Resources Information Center
Dubé, France; Dorval, Catherine; Bessette, Lyne
2013-01-01
The objective of this collaborative research is to evaluate the impact of a pedagogical intervention that combines flexible grouping and explicit instruction of reading comprehension strategies. The development of competencies is spread over a two years interval. However, despite this quite long implementation period, several Quebec students still…
Comparing Switch Costs: Alternating Runs and Explicit Cuing
ERIC Educational Resources Information Center
Altmann, Erik M.
2007-01-01
The task-switching literature routinely conflates different operational definitions of switch cost, its predominant behavioral measure. This article is an attempt to draw attention to differences between the two most common definitions, alternating-runs switch cost (ARS) and explicit-cuing switch cost (ECS). ARS appears to include both the costs…
Working Towards Explicit Modelling: Experiences of a New Teacher Educator
ERIC Educational Resources Information Center
White, Elizabeth
2011-01-01
As a new teacher educator of beginner teachers on the Graduate Teacher Programme in a large School of Education in a UK university, I have reflected on how I have been able to develop the effectiveness of modelling good professional practice to student-teachers. In this paper I will present ways in which I have made modelling more explicit, how…
The Role of Explicit Need Strength for Emotions during Learning
ERIC Educational Resources Information Center
Flunger, Barbara; Pretsch, Johanna; Schmitt, Manfred; Ludwig, Peter
2013-01-01
According to self-determination theory, the satisfaction of the basic needs for autonomy, competence, and relatedness influences achievement emotions and situational interest. The present study investigated whether domain-specific explicit need strength moderated the impact of need satisfaction/dissatisfaction on the outcomes achievement emotions…
Explicit Integration of Extremely Stiff Reaction Networks: Asymptotic Methods
Guidry, Mike W; Budiardja, R.; Feger, E.; Billings, J. J.; Hix, William Raphael; Messer, O.E.B.; Roche, K. J.; McMahon, E.; He, M.
2013-01-01
We show that, even for extremely stiff systems, explicit integration may compete in both accuracy and speed with implicit methods if algebraic methods are used to stabilize the numerical integration. The stabilizing algebra differs for systems well removed from equilibrium and those near equilibrium. This paper introduces a quantitative distinction between these two regimes and addresses the former case in depth, presenting explicit asymptotic methods appropriate when the system is extremely stiff but only weakly equilibrated. A second paper [1] examines quasi-steady-state methods as an alternative to asymptotic methods in systems well away from equilibrium and a third paper [2] extends these methods to equilibrium conditions in extremely stiff systems using partial equilibrium methods. All three papers present systematic evidence for timesteps competitive with implicit methods. Because explicit methods can execute a timestep faster than an implicit method, our results imply that algebraically stabilized explicit algorithms may offer a means to integration of larger networks than have been feasible previously in various disciplines.
Explicit versus Implicit Questioning: Inviting All Children to Think Mathematically
ERIC Educational Resources Information Center
Parks, Amy Noelle
2010-01-01
Background/Context: Open-ended, or implicit, questioning has been described as central to reform teaching in mathematics. However, concerns about equity have caused some researchers to question whether this kind of teaching is productive for all children. Purpose: This study explores the role that implicit and explicit questions played in…
An Explicitly Correlated Wavelet Method for the Electronic Schroedinger Equation
Bachmayr, Markus
2010-09-30
A discretization for an explicitly correlated formulation of the electronic Schroedinger equation based on hyperbolic wavelets and exponential sum approximations of potentials is described, covering mathematical results as well as algorithmic realization, and discussing in particular the potential of methods of this type for parallel computing.
An Explicit Formula for the Berezin Star Product
NASA Astrophysics Data System (ADS)
Xu, Hao
2012-09-01
We prove an explicit formula of the Berezin star product on Kähler manifolds. The formula is expressed as a summation over certain strongly connected digraphs. The proof relies on a combinatorial interpretation of Engliš' work on the asymptotic expansion of the Laplace integral.
Qualitative Differences between Implicit and Explicit Sequence Learning
ERIC Educational Resources Information Center
Jimenez, Luis; Vaquero, Joaquin M. M.; Lupianez, Juan
2006-01-01
Four experiments investigate the differences between implicit and explicit sequence learning concerning their resilience to structural and superficial task changes. A superficial change that embedded the SRT task in the context of a selection task, while maintaining the sequence, did selectively hinder the expression of implicit learning. In…
Effect of explicit dimensional instruction on speech category learning.
Chandrasekaran, Bharath; Yi, Han-Gyol; Smayda, Kirsten E; Maddox, W Todd
2016-02-01
Learning nonnative speech categories is often considered a challenging task in adulthood. This difficulty is driven by cross-language differences in weighting critical auditory dimensions that differentiate speech categories. For example, previous studies have shown that differentiating Mandarin tonal categories requires attending to dimensions related to pitch height and direction. Relative to native speakers of Mandarin, the pitch direction dimension is underweighted by native English speakers. In the current study, we examined the effect of explicit instructions (dimension instruction) on native English speakers' Mandarin tone category learning within the framework of a dual-learning systems (DLS) model. This model predicts that successful speech category learning is initially mediated by an explicit, reflective learning system that frequently utilizes unidimensional rules, with an eventual switch to a more implicit, reflexive learning system that utilizes multidimensional rules. Participants were explicitly instructed to focus and/or ignore the pitch height dimension, the pitch direction dimension, or were given no explicit prime. Our results show that instruction instructing participants to focus on pitch direction, and instruction diverting attention away from pitch height, resulted in enhanced tone categorization. Computational modeling of participant responses suggested that instruction related to pitch direction led to faster and more frequent use of multidimensional reflexive strategies and enhanced perceptual selectivity along the previously underweighted pitch direction dimension.
Optimizing Language Instruction: Matters of Explicitness, Practice, and Cue Learning
ERIC Educational Resources Information Center
Stafford, Catherine A.; Bowden, Harriet Wood; Sanz, Cristina
2012-01-01
Input exposure is essential for nonprimary language learning, but the importance of explicit instruction and corrective feedback continues to be debated. If instruction is required, how might it be optimized in terms of its nature and timing? In this study, 65 Spanish-English bilinguals were introduced to Latin through an interactive computer…
Attention to Explicit and Implicit Contrast in Verb Learning
ERIC Educational Resources Information Center
Childers, Jane B.; Hirshkowitz, Amy; Benavides, Kristin
2014-01-01
Contrast information could be useful for verb learning, but few studies have examined children's ability to use this type of information. Contrast may be useful when children are told explicitly that different verbs apply, or when they hear two different verbs in a single context. Three studies examine children's attention to different types of…
Explicit Constructivism: A Missing Link in Ineffective Lectures?
ERIC Educational Resources Information Center
Prakash, E. S.
2010-01-01
This study tested the possibility that interactive lectures explicitly based on activating learners' prior knowledge and driven by a series of logical questions might enhance the effectiveness of lectures. A class of 54 students doing the respiratory system course in the second year of the Bachelor of Medicine and Bachelor of Surgery program in my…
A Framework for Explicit Vocabulary Instruction with English Language Learners
ERIC Educational Resources Information Center
Nisbet, Deanna L.; Tindall, Evie R.
2015-01-01
Academic vocabulary development is critical to the success of all learners--particularly English language learners (ELLs). This article presents a framework for integrating explicit academic vocabulary instruction for ELLs into middle school classrooms. The framework embodies five research-based principles and serves as a vehicle for structuring…
Explicit- and Implicit Bullying Attitudes in Relation to Bullying Behavior
ERIC Educational Resources Information Center
van Goethem, Anne A. J.; Scholte, Ron H. J.; Wiers, Reinout W.
2010-01-01
The main aim of this study was to examine whether an assessment of implicit bullying attitudes could add to the prediction of bullying behavior after controlling for explicit bullying attitudes. Primary school children (112 boys and 125 girls, M age = 11 years, 5 months) completed two newly developed measures of implicit bullying attitudes (a…
Implicit and Explicit Learning in Individuals with Agrammatic Aphasia
ERIC Educational Resources Information Center
Schuchard, Julia; Thompson, Cynthia K.
2014-01-01
Implicit learning is a process of acquiring knowledge that occurs without conscious awareness of learning, whereas explicit learning involves the use of overt strategies. To date, research related to implicit learning following stroke has been largely restricted to the motor domain and has rarely addressed implications for language. The present…
Implicit and Explicit Attitudes Toward Sex and Romance in Asexuals.
Bulmer, Maria; Izuma, Keise
2017-03-31
Despite the recent surge of interest in sexuality, asexuality has remained relatively underresearched. Distinct from abstinence or chastity, asexuality refers to a lack of sexual attraction toward others. Past research suggests asexuals have negative attitudes toward sex, though no research has examined implicit attitudes. While preliminary evidence suggests that many asexuals are interested in engaging in romantic relationships, these attitudes have yet to be examined thoroughly, implicitly, or compared with a control group. This study investigated explicit and implicit attitudes toward sex and romance in a group of asexuals (N = 18, age M = 21.11) and a group of controls (N = 27, age M = 21.81), using the Asexuality Identification Scale (AIS), the Triangular Love Scale (TLS), semantic differentials, an Implicit Association Task (IAT), and two Single Category IATs. It was found that asexuals exhibited more negative explicit and implicit attitudes toward sex, as well as more negative explicit attitudes toward romance, relative to controls. There was no significant difference between groups on implicit romantic attitudes. Moreover, aromantic asexuals demonstrated significantly more negative explicit attitudes toward romance than romantic asexuals, though there was no significant difference between groups on implicit measures. Explanations and implications of these findings are discussed.
Resolving ambiguities of MVPA using explicit models of representation
Naselaris, Thomas; Kay, Kendrick N.
2015-01-01
We advocate a shift in emphasis within cognitive neuroscience from multivariate pattern analysis (MVPA) to the design and testing of explicit models of neural representation. With such models it becomes possible to identify the specific representations encoded in patterns of brain activity and to map them across the brain. PMID:26412094
Revisiting the Role of Explicit Genre Instruction in the Classroom
ERIC Educational Resources Information Center
Frankel, Katherine K.
2013-01-01
At the end of the twentieth century, genre theorists and practitioners debated the possibility of explicitly teaching genres in classrooms. Though the debate is decades old, it continues to be relevant to contemporary discussions about literacy instruction because it addresses questions about how to provide all students with access to genres of…
Explicit versus implicit social cognition testing in autism spectrum disorder.
Callenmark, Björn; Kjellin, Lars; Rönnqvist, Louise; Bölte, Sven
2014-08-01
Although autism spectrum disorder is defined by reciprocal social-communication impairments, several studies have found no evidence for altered social cognition test performance. This study examined explicit (i.e. prompted) and implicit (i.e. spontaneous) variants of social cognition testing in autism spectrum disorder. A sample of 19 adolescents with autism spectrum disorder and 19 carefully matched typically developing controls completed the Dewey Story Test. 'Explicit' (multiple-choice answering format) and 'implicit' (free interview) measures of social cognition were obtained. Autism spectrum disorder participants did not differ from controls regarding explicit social cognition performance. However, the autism spectrum disorder group performed more poorly than controls on implicit social cognition performance in terms of spontaneous perspective taking and social awareness. Findings suggest that social cognition alterations in autism spectrum disorder are primarily implicit in nature and that an apparent absence of social cognition difficulties on certain tests using rather explicit testing formats does not necessarily mean social cognition typicality in autism spectrum disorder.
Presenting Lexical Bundles for Explicit Noticing with Schematic Linguistic Representation
ERIC Educational Resources Information Center
Thomson, Haidee Elizabeth
2016-01-01
Lexical bundles are essential for fluency, but their incompleteness is a stumbling block for learners. In this study, two presentation methods to increase awareness of lexical bundles through explicit noticing are explored and compared with incidental exposure. The three conditions in this study were as follows: noticing with schematic linguistic…
Revising Geology Labs To Explicitly Use the Scientific Method.
ERIC Educational Resources Information Center
Hannula, Kimberly A.
2003-01-01
Proposes that content- or skill-based labs can be revised to explicitly involve the scientific method by asking students to propose hypotheses before making observations. Students' self-assessment showed they felt that they learned a great deal from this style of labs and found the labs to be fun; however, students felt that they learned little…
The Order of Explicit Information in Processing Instruction
ERIC Educational Resources Information Center
McNulty Diaz, Erin
2017-01-01
The two main components of Processing Instruction (PI) are Explicit Information (EI) and Structured Input (SI). Most researchers have concluded that the SI is more responsible for learner gains than the EI (Benati, 2004a, 2004b; VanPatten & Oikennon, 1996; Wong, 2004). However, some researchers have found that EI does significantly impact…
"See Translation": Explicit and Implicit Language Policies on Facebook
ERIC Educational Resources Information Center
Hendus, Ulrike
2015-01-01
The currently tested "See Translation" button can be considered an expression of Facebook's explicit language policy. It offers the users fast and easy translations of others' status updates and can therefore be seen as diminishing language barriers and reducing the need for a lingua franca in polylingual networks, thus enhancing…
Are Explicit Apologies Proportional to the Offenses They Address?
ERIC Educational Resources Information Center
Heritage, John; Raymond, Chase Wesley
2016-01-01
We consider here Goffman's proposal of proportionality between virtual offenses and remedial actions, based on the examination of 102 cases of explicit apologies. To this end, we offer a typology of the primary apology formats within the dataset, together with a broad categorization of the types of virtual offenses to which these apologies are…
Measuring Implicit and Explicit Attitudes toward Foreign-Accented Speech
ERIC Educational Resources Information Center
Pantos, Andrew J.
2010-01-01
The purpose of this research was to investigate the nature of listeners' attitudes toward foreign-accented speech and the manner in which those attitudes are formed. This study measured 165 participants' implicit and explicit attitudes toward US- and foreign-accented audio stimuli. Implicit attitudes were measured with an audio Implicit…
Explicit-Implicit Distinction: A Review of Related Literature
ERIC Educational Resources Information Center
Jarrah, Marwan A.
2016-01-01
This paper sketches out the main views of the major pragmatic approaches (i.e., Grice's theory of conversation, Relevance Theory, and Neo-Gricean pragmatic theory) on explicit-implicit distinction. It makes clear how this distinction has been differently drawn for utterance interpretation. Additionally, it highlights several corresponding problems…
Implicit and Explicit Recasts in L2 Oral French Interaction
ERIC Educational Resources Information Center
Erlam, Rosemary; Loewen, Shawn
2010-01-01
This laboratory-based study of second- and third-year American university students learning French examines the effectiveness of implicit and explicit corrective feedback on noun-adjective agreement errors. The treatment consisted of one hour of interactive tasks. Implicit feedback was operationalized as a single recast with interrogative…
Making the Tacit Explicit: Children's Strategies for Classroom Writing
ERIC Educational Resources Information Center
Silby, Alison; Watts, Mike
2015-01-01
A key highlight of this study is generating evidence of children "making aware the unaware", making tacit knowledge explicit. The research explores the levels of awareness in thinking used by eight 7-8 year-old children when engaged in school-based genre writing tasks. The focus is on analysing children's awareness of their thought…
Nonlinear Vibration of a Magnetic Spring
ERIC Educational Resources Information Center
Zhong, Juhua; Cheng, Zhongqi; Ge, Ziming; Zhang, Yuelan; Lu, Wenqiang; Song, Feng; Li, Chuanyong
2012-01-01
To demonstrate the different vibration characteristics of a magnetic spring compared with those of a metal one, a magnetic spring apparatus was constructed from a pair of circular magnets of the same size with an inside diameter of 2.07 cm and an outside diameter of 4.50 cm. To keep the upper magnet in a suspension state, the two magnets were…
Modeling the evolution of galactic magnetic fields
Yar-Mukhamedov, D.
2015-04-15
An analytic model for evolution of galactic magnetic fields in hierarchical galaxy formation frameworks is introduced. Its major innovative components include explicit and detailed treatment of the physics of merger events, mass gains and losses, gravitational energy sources and delays associated with formation of large-scale magnetic fields. This paper describes the model, its implementation, and core results obtained by its means.
The importance of explicitly mapping instructional analogies in science education
NASA Astrophysics Data System (ADS)
Asay, Loretta Johnson
Analogies are ubiquitous during instruction in science classrooms, yet research about the effectiveness of using analogies has produced mixed results. An aspect seldom studied is a model of instruction when using analogies. The few existing models for instruction with analogies have not often been examined quantitatively. The Teaching With Analogies (TWA) model (Glynn, 1991) is one of the models frequently cited in the variety of research about analogies. The TWA model outlines steps for instruction, including the step of explicitly mapping the features of the source to the target. An experimental study was conducted to examine the effects of explicitly mapping the features of the source and target in an analogy during computer-based instruction about electrical circuits. Explicit mapping was compared to no mapping and to a control with no analogy. Participants were ninth- and tenth-grade biology students who were each randomly assigned to one of three conditions (no analogy module, analogy module, or explicitly mapped analogy module) for computer-based instruction. Subjects took a pre-test before the instruction, which was used to assign them to a level of previous knowledge about electrical circuits for analysis of any differential effects. After the instruction modules, students took a post-test about electrical circuits. Two weeks later, they took a delayed post-test. No advantage was found for explicitly mapping the analogy. Learning patterns were the same, regardless of the type of instruction. Those who knew the least about electrical circuits, based on the pre-test, made the most gains. After the two-week delay, this group maintained the largest amount of their gain. Implications exist for science education classrooms, as analogy use should be based on research about effective practices. Further studies are suggested to foster the building of research-based models for classroom instruction with analogies.
Explicit and implicit self-evaluations in social anxiety disorder.
Gilboa-Schechtman, Eva; Keshet, Hadar; Livne, Tamar; Berger, Uri; Zabag, Reut; Hermesh, Haggai; Marom, Sofi
2017-04-01
Cognitive models of social anxiety disorder (SAD) emphasize the role of explicit and implicit self-evaluations (SEs) in the etiology and maintenance of this condition. Whereas individuals with SAD consistently report lower explicit SEs as compared with nonanxious individuals, findings concerning implicit SEs are mixed. To gain a more nuanced understanding of the nature of SEs in SAD, we examined explicit and implicit SEs in two significant interpersonal domains: social rank and affiliation. Consistent with cognitive theorizing, we predicted that, compared to nonclinical controls (NCCs), individuals with SAD would exhibit lower explicit and implicit SEs in both domains. Guided by evolutionary theories we also predicted that the differences in SEs between the groups would be greater in the social rank, as compared to the affiliation, domain. Individuals diagnosed with SAD (n = 38) and NCCs) n = 40) performed two variants of the Self Implicit Association Test: one concerning social rank, and the other concerning affiliation. They also rated themselves on social-rank and affiliation traits. We found that, as compared to NCCs, individuals with SAD exhibited lower social-rank and affiliation SEs. Moreover, differences between the groups in social-rank SEs were greater than in affiliation SEs. Importantly, this pattern was evident in implicit SEs, as much as in explicit SEs. Our findings dovetail with evolutionary accounts highlighting the centrality of the social-rank system in SAD, and refine central tenets of cognitive theories of SAD. A multidomain, multimethod approach to the understanding of the self may broaden our conceptualization of SAD and related disorders. (PsycINFO Database Record
Garcia-Ravelo, J.; Trujillo, A. L.; Schulze-Halberg, A.
2012-10-15
We obtain explicit formulas for perturbative corrections of the infinite quantum well model. The formulas we obtain are based on a class of matrix elements that we construct by means of two-parameter ladder operators associated with the infinite quantum well system. Our approach can be used to construct solutions to Schroedinger-type equations that involve generalized harmonic perturbations of their potentials, such as cosine powers, Fourier series, and more general functions. As a particular case, we obtain characteristic values for odd periodic solutions of the Mathieu equation.
Fermionic vacuum polarization by an Abelian magnetic tube in the cosmic string spacetime
NASA Astrophysics Data System (ADS)
Maior de Sousa, M. S.; Ribeiro, R. F.; Bezerra de Mello, E. R.
2017-02-01
In this paper, we consider a charged massive fermionic quantum field in the idealized cosmic string spacetime and in the presence of a magnetic field confined in a cylindrical tube of finite radius. Three distinct configurations for the magnetic fields are taken into account: (i) a cylindrical shell of radius a , (ii) a magnetic field proportional to 1 /r , and (iii) a constant magnetic field. In these three cases, the axis of the infinitely long tube of radius a coincides with the cosmic string. Our main objectives in this paper are to analyze the fermionic condensate (FC) and the vacuum expectation value (VEV) of the fermionic energy-momentum tensor. In order to do that, we explicitly construct the complete set of normalized wave functions for each configuration of the magnetic field. We show that in the region outside the tube, the FC and the VEV of the energy-momentum tensor are decomposed into two parts: The first ones correspond to the zero-thickness magnetic flux contributions, and the second ones are induced by the nontrivial structure of the magnetic field, named core-induced contributions. The latter present specific forms depending on the magnetic field configuration considered. We also show that the VEV of the energy-momentum tensor is diagonal and obeys the conservation condition, and its trace is expressed in terms of the fermionic condensate. The zero-thickness contributions to the FC and VEV of the energy-momentum tensor depend only on the fractional part of the ration of the magnetic flux inside the tube by the quantum one. As to the core-induced contributions, they depend on the total magnetic flux inside the tube and, consequently, in general, are not a periodic function of the magnetic flux.
Dehdashtian, Sara; Gholivand, Mohammad Bagher; Shamsipur, Mojtaba; Kariminia, Samira
2016-01-01
A simple and sensitive sensor based on carbon paste electrode (CPE) modified by chitosan-coated magnetic nanoparticle (CMNP) was developed for the electrochemical determination of morphine (MO). The proposed sensor was characterized with scanning electron microscopy (SEM) and electrochemical impedance spectroscopy (EIS). The electrooxidation of MO was studied on modified carbon paste electrode using cyclic voltammetry, chronoamperometry and differential pulse voltammetry as diagnostic techniques. The oxidation peak potential of morphine on the CMNP/CPE appeared at 380 mV which was accompanied with smaller overpotential and increase in oxidation peak current compared to that obtained on the bare carbon paste electrode (CPE). Under optimum conditions the sensor provides two linear DPV responses in the range of 10-2000 nM and 2-720 μM for MO with a detection limit of 3 nM. The proposed sensor was successfully applied for monitoring of MO in serum and urine samples and satisfactory results were obtained.
NASA Astrophysics Data System (ADS)
Medley, S. S.; Roquemore, A. L.
1998-07-01
A novel charge exchange spectrometer using a dee-shaped region of parallel electric and magnetic fields was developed at the Princeton Plasma Physics Laboratory for neutral particle diagnostics on the Tokamak Fusion Test Reactor (TFTR). The E∥B spectrometer has an energy range of 0.5⩽A (amu)E (keV)⩽600 and provides mass-resolved energy spectra of H+, D+, and T+ (or 3He+) ion species simultaneously during a single discharge. The detector plane exhibits parallel rows of analyzed ions, each row containing the energy dispersed ions of a given mass-to-charge ratio. The detector consists of a large area microchannel plate (MCP) which is provided with three rectangular, semicontinuous active area strips, one coinciding with each of the mass rows for detection of H+, D+, and T+ (or 3He+) and each mass row has 75 energy channels. To suppress spurious signals attending operation of the plate in the magnetic fringe field of the spectrometer, the MCP was housed in a double-walled iron shield with a wire mesh ion entrance window. Using an accelerator neutron generator, the MCP neutron detection efficiency was measured to be 1.7×10-3 and 6.4×10-3 counts/neutron/cm2 for 2.5 MeV-DD and 14 MeV-DT neutrons, respectively. The design and calibration of the spectrometer are described in detail, including the effect of MCP exposure to tritium, and results obtained during high performance D-D operation on TFTR are presented to illustrate the performance of the E∥B spectrometer. The spectrometers were not used during D-T plasma operation due to the cost of providing the required radiation shielding.
Einstein, Harry; Grimes, Patrick G.
1983-08-23
An electrochemical cell construction features a novel co-extruded plastic electrode in an interleaved construction with a novel integral separator-spacer. Also featured is a leak and impact resistant construction for preventing the spill of corrosive materials in the event of rupture.
Suslow, T; Kugel, H; Reber, H; Bauer, J; Dannlowski, U; Kersting, A; Arolt, V; Heindel, W; Ohrmann, P; Egloff, B
2010-04-28
Extraversion/introversion is a basic dimension of personality that describes individual differences in social behavior and sensory sensitivity. Previous neuroimaging research exclusively relied on self reports for assessing personality traits. In recent years, implicit measures of personality have been developed that aim at assessing the implicit self-concept of personality and complement self report instruments which are thought to measure aspects of the explicit self-concept of personality. In the present study functional magnetic resonance imaging was used to examine automatic brain reactivity to facial expression as a function of both implicitly and explicitly measured extraversion in 30 healthy women. Sad, happy, and neutral faces were presented for 33 ms masked by neutral faces beside a no face control condition. Subjects evaluated the briefly shown neutral mask faces. The Implicit Association Test (IAT) and the NEO Five-Factor Inventory (NEO-FFI) were applied as measures of extraversion which were not correlated in our sample. IAT extraversion was negatively correlated with automatic reactivity of the caudate head, thalamus, and inferior frontal cortex to sad faces. NEO-FFI extraversion was negatively correlated with response of the inferior frontal cortex and putamen to sad faces. For masked happy faces, an inverse correlation of the IAT effect for extraversion with activation of the caudate head and superior parietal lobule was observed. NEO-FFI extraversion was inversely correlated with the response of the thalamus to happy faces. Neither NEO-FFI extraversion nor IAT effect were significantly related to brain response to masked neutral faces (compared to the no face condition). Taken together, a specific heightened responsivity of the fronto-striatal-thalamic circuit to facial emotions which are arousing stimuli might underlie introverts' preference for avoiding social interactions. Research on the neurobiology of extraversion could benefit from the
Theory of nuclear magnetic relaxation
NASA Technical Reports Server (NTRS)
Mcconnell, J.
1983-01-01
A theory of nuclear magnetic interaction is based on the study of the stochastic rotation operator. The theory is applied explicitly to relaxation by anisotropic chemical shift and to spin-rotational interactions. It is applicable also to dipole-dipole and quadrupole interactions.
Development of an explicit non-staggered scheme for solving three-dimensional Maxwell's equations
NASA Astrophysics Data System (ADS)
Sheu, Tony W. H.; Chung, Y. W.; Li, J. H.; Wang, Y. C.
2016-10-01
An explicit finite-difference scheme for solving the three-dimensional Maxwell's equations in non-staggered grids is presented. We aspire to obtain time-dependent solutions of the Faraday's and Ampère's equations and predict the electric and magnetic fields within the discrete zero-divergence context (or Gauss's law). The local conservation laws in Maxwell's equations are numerically preserved using the explicit second-order accurate symplectic partitioned Runge-Kutta temporal scheme. Following the method of lines, the spatial derivative terms in the semi-discretized Faraday's and Ampère's equations are approximated theoretically to obtain a highly accurate numerical phase velocity. The proposed fourth-order accurate space-centered finite difference scheme minimizes the discrepancy between the exact and numerical phase velocities. This minimization process considerably reduces the dispersion and anisotropy errors normally associated with finite difference time-domain methods. The computational efficiency of getting the same level of accuracy at less computing time and the ability of preserving the symplectic property have been numerically demonstrated through several test problems.
Labudda, Kirsten; Woermann, Friedrich G; Mertens, Markus; Pohlmann-Eden, Bernd; Markowitsch, Hans J; Brand, Matthias
2008-06-01
Recent functional neuroimaging and lesion studies demonstrate the involvement of the orbitofrontal/ventromedial prefrontal cortex as a key structure in decision making processes. This region seems to be particularly crucial when contingencies between options and consequences are unknown but have to be learned by the use of feedback following previous decisions (decision making under ambiguity). However, little is known about the neural correlates of decision making under risk conditions in which information about probabilities and potential outcomes is given. In the present study, we used functional magnetic resonance imaging to measure blood-oxygenation-level-dependent (BOLD) responses in 12 subjects during a decision making task. This task provided explicit information about probabilities and associated potential incentives. The responses were compared to BOLD signals in a control condition without information about incentives. In contrast to previous decision making studies, we completely removed the outcome phase following a decision to exclude the potential influence of feedback previously received on current decisions. The results indicate that the integration of information about probabilities and incentives leads to activations within the dorsolateral prefrontal cortex, the posterior parietal lobe, the anterior cingulate and the right lingual gyrus. We assume that this pattern of activation is due to the involvement of executive functions, conflict detection mechanisms and arithmetic operations during the deliberation phase of decisional processes that are based on explicit information.
NASA Astrophysics Data System (ADS)
Stanke, Monika; Palikot, Ewa; KÈ©dziera, Dariusz; Adamowicz, Ludwik
2016-12-01
An algorithm for calculating the first-order electronic orbit-orbit magnetic interaction correction for an electronic wave function expanded in terms of all-electron explicitly correlated molecular Gaussian (ECG) functions with shifted centers is derived and implemented. The algorithm is tested in calculations concerning the H2 molecule. It is also applied in calculations for LiH and H3+ molecular systems. The implementation completes our work on the leading relativistic correction for ECGs and paves the way for very accurate ECG calculations of ground and excited potential energy surfaces (PESs) of small molecules with two and more nuclei and two and more electrons, such as HeH-, H3+, HeH2, and LiH2+. The PESs will be used to determine rovibrational spectra of the systems.
Bian, Xing-Ming; Liu, Lin; Li, Hai-Bing; Wang, Chan-Yuan; Xie, Qing; Zhao, Quan-Liang; Bi, Song; Hou, Zhi-Ling
2017-01-27
Since manipulating electromagnetic waves with electromagnetic active materials for environmental and electric engineering is a significant task, here a novel prototype is reported by introducing reduced graphene oxide (RGO) interfaces in carbon fiber (CF) networks for a hierarchical carbon fiber/reduced graphene oxide/nickel (CF-RGO-Ni) composite textile. Upon charaterizations of the microscopic morphologies, electrical and magnetic properties, the presence of three-dimensional RGO interfaces and bifunctional nickel nanoparticles substantially influences the related physical properties in the resulting hierarchical composite textiles. Eletromagnetic interference (EMI) shielding performance suggests that the hierarchical composite textiles hold a strong shielding effectiveness greater than 61 dB, showing greater advantages than conventional polymeric and foamy shielding composites. As a polymer-free lightweight structure, flexible CF-RGO-Ni composites of all electromagnetic active components offer unique understanding of the multi-scale and multiple mechanisms in electromagnetic energy consumption. Such a novel prototype of shielding structures along with convenient technology highlight a strategy to achieve high-performance EMI shielding, coupled with a universal approach for preparing advanced lightweight composites with graphene interfaces.
NASA Astrophysics Data System (ADS)
Bian, Xing-Ming; Liu, Lin; Li, Hai-Bing; Wang, Chan-Yuan; Xie, Qing; Zhao, Quan-Liang; Bi, Song; Hou, Zhi-Ling
2017-01-01
Since manipulating electromagnetic waves with electromagnetic active materials for environmental and electric engineering is a significant task, here a novel prototype is reported by introducing reduced graphene oxide (RGO) interfaces in carbon fiber (CF) networks for a hierarchical carbon fiber/reduced graphene oxide/nickel (CF-RGO-Ni) composite textile. Upon charaterizations of the microscopic morphologies, electrical and magnetic properties, the presence of three-dimensional RGO interfaces and bifunctional nickel nanoparticles substantially influences the related physical properties in the resulting hierarchical composite textiles. Eletromagnetic interference (EMI) shielding performance suggests that the hierarchical composite textiles hold a strong shielding effectiveness greater than 61 dB, showing greater advantages than conventional polymeric and foamy shielding composites. As a polymer-free lightweight structure, flexible CF-RGO-Ni composites of all electromagnetic active components offer unique understanding of the multi-scale and multiple mechanisms in electromagnetic energy consumption. Such a novel prototype of shielding structures along with convenient technology highlight a strategy to achieve high-performance EMI shielding, coupled with a universal approach for preparing advanced lightweight composites with graphene interfaces.
Madrakian, Tayyebeh; Haghshenas, Esmaeel; Ahmadi, Mazaher; Afkhami, Abbas
2015-06-15
A novel magneto multiwalled carbon nanotube/carbon paste electrode (MMW/CPE) for the determination of mefenamic acid (MFA) was introduced. Magnetic molecularly imprinted polymer nanoparticles (MMIPNPs) were synthesized and then added to the solution of MFA. After stirring for 20 min, the MMW/CPE was immersed in the solution of MFA (contain MMIPNPs) and the MMIPNPs were captured by it. Then oxidation of MFA was analyzed by differential pulse voltammetry (DPV). Electrochemical impedance spectroscopy, cyclic voltammetry, and DPV were employed to characterize the MMW/CPE. The MMIPNPs exhibited a high selectivity and sensitivity toward MFA. The effect of various experimental parameters including pH, MMIPNPs dosage, stirring time, accumulation potential and time on the voltammetric response of MFA were investigated. Under the optimal conditions, selective detection of MFA in a linear concentration range of 2.0-1000.0 nmol L(-1) was performed with the detection limit of 1.2 nmol L(-1) (3S/N). To further study the practical applicability of this method, it was applied to the analysis of some real samples and the obtained results were satisfactory.
An explicit-solvent conformation search method using open software
Gaalswyk, Kari
2016-01-01
Computer modeling is a popular tool to identify the most-probable conformers of a molecule. Although the solvent can have a large effect on the stability of a conformation, many popular conformational search methods are only capable of describing molecules in the gas phase or with an implicit solvent model. We have developed a work-flow for performing a conformation search on explicitly-solvated molecules using open source software. This method uses replica exchange molecular dynamics (REMD) to sample the conformational states of the molecule efficiently. Cluster analysis is used to identify the most probable conformations from the simulated trajectory. This work-flow was tested on drug molecules α-amanitin and cabergoline to illustrate its capabilities and effectiveness. The preferred conformations of these molecules in gas phase, implicit solvent, and explicit solvent are significantly different. PMID:27280078
Implicit versus explicit momentum relaxation time solution for semiconductor nanowires
Marin, E. G. Ruiz, F. G. Godoy, A. Tienda-Luna, I. M.; Gámiz, F.
2015-07-14
We discuss the necessity of the exact implicit Momentum Relaxation Time (MRT) solution of the Boltzmann transport equation in order to achieve reliable carrier mobility results in semiconductor nanowires. Firstly, the implicit solution for a 1D electron gas with a isotropic bandstructure is presented resulting in the formulation of a simple matrix system. Using this solution as a reference, the explicit approach is demonstrated to be inaccurate for the calculation of inelastic anisotropic mechanisms such as polar optical phonons, characteristic of III-V materials. Its validity for elastic and isotropic mechanisms is also evaluated. Finally, the implications of the MRT explicit approach inaccuracies on the total mobility of Si and III-V NWs are studied.
Highly stable explicit technique for stiff reaction-transport PDEs
Aro, C. J., LLNL
1996-12-01
The numerical simulation of chemically reacting flows is a topic that has attracted a great deal of current research. At the heart of numerical reactive flow simulations are large sets of coupled, nonlinear partial differential equations (PDEs). Due to the stiffness that is usually present, explicit time differencing schemes are not used despite their inherent simplicity and efficiency on parallel and vector machines, since these schemes require prohibitively small numerical stepsizes. Implicit time differencing schemes, although possessing good stability characteristics, introduce a great deal of computational overhead necessary to solve the simultaneous algebraic system at each timestep. This paper proposes an algorithm based on a preconditioned time differencing scheme. The algorithm is explicit and permits a large stable time step. A study of the algorithm's performance on a parallel architecture is presented.
Alcohol affects goal commitment by explicitly and implicitly induced myopia.
Sevincer, A Timur; Oettingen, Gabriele; Lerner, Tobias
2012-05-01
Alcohol commits people to personally important goals even if expectations of reaching the goals are low. To illuminate this effect, we used alcohol myopia theory, stating that alcohol intoxicated people disproportionally attend to the most salient aspects of a situation and ignore peripheral aspects. When low expectations of reaching an important goal were activated students who consumed alcohol were less committed than students who consumed a placebo. We observed less commitment regardless of whether low expectations were explicitly activated in a questionnaire (Study 1) or implicitly activated through subliminal priming (Study 2). The results imply that, intoxicated people commit to goals according to what aspects of a goal are activated either explicitly or implicitly.
Approximate explicit analytic solution of the Elenbaas-Heller equation
NASA Astrophysics Data System (ADS)
Liao, Meng-Ran; Li, Hui; Xia, Wei-Dong
2016-08-01
The Elenbaas-Heller equation describing the temperature field of a cylindrically symmetrical non-radiative electric arc has been solved, and approximate explicit analytic solutions are obtained. The radial distributions of the heat-flux potential and the electrical conductivity have been figured out briefly by using some special simplification techniques. The relations between both the core heat-flux potential and the electric field with the total arc current have also been given in several easy explicit formulas. Besides, the special voltage-ampere characteristic of electric arcs is explained intuitionally by a simple expression involving the Lambert W-function. The analyses also provide a preliminary estimation of the Joule heating per unit length, which has been verified in previous investigations. Helium arc is used to examine the theories, and the results agree well with the numerical computations.
On explicit algebraic stress models for complex turbulent flows
NASA Technical Reports Server (NTRS)
Gatski, T. B.; Speziale, C. G.
1992-01-01
Explicit algebraic stress models that are valid for three-dimensional turbulent flows in noninertial frames are systematically derived from a hierarchy of second-order closure models. This represents a generalization of the model derived by Pope who based his analysis on the Launder, Reece, and Rodi model restricted to two-dimensional turbulent flows in an inertial frame. The relationship between the new models and traditional algebraic stress models -- as well as anistropic eddy visosity models -- is theoretically established. The need for regularization is demonstrated in an effort to explain why traditional algebraic stress models have failed in complex flows. It is also shown that these explicit algebraic stress models can shed new light on what second-order closure models predict for the equilibrium states of homogeneous turbulent flows and can serve as a useful alternative in practical computations.
Toward an explicit analysis of generalization: A stimulus control interpretation
Kirby, Kimberly C.; Bickel, Warren K.
1988-01-01
Producing generality of treatment effects to new settings has been a critical concern for applied behavior analysts, but a systematic and reliable means of producing generality has yet to be provided. We argue that the principles of stimulus control and reinforcement underlie the production of most generalized effects; therefore, we suggest interpreting generalization programming in terms of stimulus control. The generalization programming procedures identified by Stokes and Baer (1977) are discussed in terms of both the stimulus control tactics explicitly identified and those that may be operating but are not explicitly identified. Our interpretation clarifies the critical components of Stokes and Baer's procedures and places greater emphasis on planning for generalization as a part of training procedures. PMID:22478006
The use of explicit building blocks in evolutionary computation
NASA Astrophysics Data System (ADS)
Sangkavichitr, Chalermsub; Chongstitvatana, Prabhas
2016-02-01
This paper proposes a new algorithm to identify and compose building blocks. Building blocks are interpreted as common subsequences between good individuals. The proposed algorithm can extract building blocks from a population explicitly. Explicit building blocks are identified from shared alleles among multiple chromosomes. These building blocks are stored in an archive. They are recombined to generate offspring. The additively decomposable problems and hierarchical decomposable problems are used to validate the algorithm. The results are compared with the Bayesian optimisation algorithm, the hierarchical Bayesian optimisation algorithm, and the chi-square matrix. This proposed algorithm is simple, effective, and fast. The experimental results confirm that building block identification is an important process that guides the recombination procedure to improve the solutions. In addition, the method efficiently solves hard problems.
Explicitly correlated multireference configuration interaction: MRCI-F12.
Shiozaki, Toru; Knizia, Gerald; Werner, Hans-Joachim
2011-01-21
An internally contracted multireference configuration interaction is developed which employs wave functions that explicitly depend on the electron-electron distance (MRCI-F12). This MRCI-F12 method has the same applicability as the MRCI method, while having much improved basis-set convergence with little extra computational cost. The F12b approximation is used to arrive at a computationally efficient implementation. The MRCI-F12 method is applied to the singlet-triplet separation of methylene, the dissociation energy of ozone, properties of diatomic molecules, and the reaction barrier and exothermicity of the F + H(2) reaction. These examples demonstrate that already with basis sets of moderate size the method provides near complete basis set MRCI accuracy, and hence quantitative agreement with the experimental data. As a side product, we have also implemented the explicitly correlated multireference averaged coupled pair functional method (MRACPF-F12).
An explicit-implicit solution of the hydrodynamic and radiation equations
NASA Astrophysics Data System (ADS)
Sahota, Manjit S.
A solution of the coupled radiation-hydrodynamic equations on a median mesh is presented for a transient, three-dimensional, compressible, multimaterial, free-Lagrangian code. The code uses fixed-mass particles surrounded by median Lagrangian cells. These cells are free to change connectivity, which ensures accuracy in the differencing of equations and allows the code to handle extreme distortions. All calculations are done on a median Lagrangian mesh that is constructed from the Delaunay tetrahedral mesh using the Voronoi connection algorithm. Because each tetrahedron volume is shared equally by the four mass points (computational cells) located at the tetrahedron vertices, calculations are done at a tetrahedron level for enhanced computational efficiency, and the rate-of-change data are subsequently accumulated at mass points from these tetrahedral contributions. The hydrodynamic part of the calculations is done using an explicit time-advancement technique, and the radiation calculations are done using a hybrid explicit-implicit time-advancement scheme in the equilibrium-diffusion limit. An explicit solution of the radiation-diffusion equation is obtained for cells that meet the current time-step criterion imposed by the hydrodynamic solution, and a fully implicit point-relaxation solution is obtained elsewhere without defining an inversion matrix. The approach has a distinct advantage over the conventional matrix-inversion approaches, because defining such a matrix for an unstructured grid is both cumbersome and computationally intensive. The new algorithm runs >20 times faster than a matrix-solver approach using the conjugate-gradient technique, and is easily parallelizable on the Cray family of supercomputers. With the new algorithm, the radiation-diffusion part of the calculation runs about twice as fast as the hydrodynamic part of the calculation. The code conserves mass, momentum, and energy exactly, except in some pathological situations.
NFFLOW: A reservoir simulator incorporating explicit fractures (SPE 153890)
Boyle, E.J.; Sams, W.N.
2012-01-01
NFFLOW is a research code that quickly and inexpensively simulates flow in moderately fractured reservoirs. It explicitly recognizes fractures separately from rock matrix. In NFFLOW fracture flow is proportional to the pressure gradient along the fracture, and flow in the rock matrix is determined by Darcy’s Law. The two flow mechanisms are coupled through the pressure gradient between a fracture and its adjacent rock matrix. Presented is a promising change to NFFLOW that allows for flow across a rock matrix block.
Quasi-explicit algebraic turbulence closures for compressible reacting flows
NASA Astrophysics Data System (ADS)
Adumitroaie, Virgil
A consistent and complete set of quasi-explicit algebraic closures for turbulent reacting flows is proposed as approximate solutions to the full second order moment equations. Quasi-explicit algebraic scalar flux models that are valid for three-dimensional turbulent flows are derived from a hierarchy of second-order moment closures. The mathematical procedure is based on the Cayley-Hamilton theorem and is an extension of the scheme developed by Taulbee (1992). Several closures for the pressure-scalar gradient correlations are considered and explicit algebraic relations are provided for the velocity-scalar correlations in both non-reacting and reacting flows. In the latter, the role of the Damkohler number is exhibited in isothermal turbulent flows with nonpremixed reactants. The relationship between these closures and traditional models based on the linear gradient diffusion approximation is theoretically established. The results of model predictions are assessed via comparison with available laboratory data in turbulent jet flows. The development of the quasi-explicit algebraic models for Reynolds stresses, temperature fluxes and reacting scalar fluxes is extended to high-speed turbulent reacting flows under a density weighted average formalism. New closures are proposed for the pressure-strain and the pressure-scalar gradient correlations. These accommodate compressibility corrections subject to the magnitude of the turbulent Mach number, the density gradient, the pressure gradient and the mean dilatation effects. Non-reacting and reacting flows with heat release are considered. In the latter, a second-order irreversible chemical reactions in turbulent flows with initially segregated reactants is considered. The models are tested in simple compressible free-shear flows. Comparisons are made between the full second order moment computations and the algebraic closure predictions. For a mixing layer, experimental data are used to validate the predicted results.
LETTER TO THE EDITOR: Explicit finite inverse Hilbert transforms
NASA Astrophysics Data System (ADS)
You, Jiangsheng; Zeng, Gengsheng L.
2006-06-01
Recently, Noo and coworkers discovered an explicit inversion formula for the finite Hilbert transform, which is very important to accurate reconstruction from truncated projections. This letter presents two formulae for the finite inverse Hilbert transform using some elementary complex variable analysis. The new formulae do not contain the constant C and the singular endpoints that exist in the formula in Noo et al (2004 Phys. Med. Biol. 49 3903-23).
An explicit André-Oort type result for
NASA Astrophysics Data System (ADS)
Paulin, Roland
2015-07-01
Using class field theory we prove an explicit result of Andr\\'e-Oort type for $\\mathbb{P}^1(\\mathbb{C}) \\times \\mathbb{G}_m(\\mathbb{C})$. In this variation the special points of $\\mathbb{P}^1(\\mathbb{C})$ are the singular moduli, while the special points of $\\mathbb{G}_m(\\mathbb{C})$ are defined to be the roots of unity.
On the explicit solutions of the elliptic Calogero system
NASA Astrophysics Data System (ADS)
Gavrilov, L.; Perelomov, A. M.
1999-12-01
Let q1,q2,…,qN be the coordinates of N particles on the circle, interacting with the integrable potential ∑j
Modeling the Explicit Chemistry of Anthropogenic and Biogenic Organic Aerosols
Madronich, Sasha
2015-12-09
The atmospheric burden of Secondary Organic Aerosols (SOA) remains one of the most important yet uncertain aspects of the radiative forcing of climate. This grant focused on improving our quantitative understanding of SOA formation and evolution, by developing, applying, and improving a highly detailed model of atmospheric organic chemistry, the Generation of Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A) model. Eleven (11) publications have resulted from this grant.
Explicit photochemical mechanism for atmospheric oxidation of n-butane
Wen, L.
1992-01-01
Alkanes, being an important component of atmosphere, serve as precursors to ozone formation in urban and rural air masses. An explicit photochemical oxidation mechanism for n-butane, which is the major hydrocarbon component of automobile exhaust, is created in this work. The yields of organic nitrates from n-butane, n-pentane, and methyl ethyl ketone photooxidations were studied in Teflon bag and smog chamber experiments. Comparing with the expression currently using the most atmospheric model studies, the total butyl nitrates yield obtained in this work is about 36% lower, and the ratio of primary to secondary butyl nitrates is slightly higher. It is shown in this work that the yields of hydroxyl and carbonyl butyl nitrates are very low, and can be ignored in the explicit photochemical mechanisms. The explicit photochemical oxidation mechanism for methyl ethyl ketone (MEK) was created first because it is the major product from photooxidation of n-butane. The explicit photochemical oxidation mechanism for n-butane, created later, draws on the MEK mechanism. The mechanisms were tested by comparing model predictions with experimental observations from smog chamber experiments. The comparisons were conducted for species which had experimental observation data, such as O[sub 3], NO, and NO[sub 2], n-butane, MEK, organic nitrates, and aldehydes species. The sixteen smog chamber experiments, used in model simulations, were conducted during 1978 to 1992. The mechanisms are mainly based on the available kinetic data in literature and the experimental result in this work. The rate constants for some reactions in the mechanisms were adjusted to make a better fit with the experimental observations. These reactions were: reaction of OH and n-butane to form secondary butyl peroxy radical, decomposition of secondary butoxy radical, and reaction of OH and MEK.
Explicit Low-Thrust Guidance for Reference Orbit Targeting
NASA Technical Reports Server (NTRS)
Lam, Try; Udwadia, Firdaus E.
2013-01-01
The problem of a low-thrust spacecraft controlled to a reference orbit is addressed in this paper. A simple and explicit low-thrust guidance scheme with constrained thrust magnitude is developed by combining the fundamental equations of motion for constrained systems from analytical dynamics with a Lyapunov-based method. Examples are given for a spacecraft controlled to a reference trajectory in the circular restricted three body problem.
Explicit Integration of Extremely Stiff Reaction Networks: Partial Equilibrium Methods
Guidry, Mike W; Billings, J. J.; Hix, William Raphael
2013-01-01
In two preceding papers [1,2] we have shown that, when reaction networks are well removed from equilibrium, explicit asymptotic and quasi-steady-state approximations can give algebraically stabilized integration schemes that rival standard implicit methods in accuracy and speed for extremely stiff systems. However, we also showed that these explicit methods remain accurate but are no longer competitive in speed as the network approaches equilibrium. In this paper we analyze this failure and show that it is associated with the presence of fast equilibration timescales that neither asymptotic nor quasi-steady-state approximations are able to remove efficiently from the numerical integration. Based on this understanding, we develop a partial equilibrium method to deal effectively with the new partial equilibrium methods, give an integration scheme that plausibly can deal with the stiffest networks, even in the approach to equilibrium, with accuracy and speed competitive with that of implicit methods. Thus we demonstrate that algebraically stabilized explicit methods may offer alternatives to implicit integration of even extremely stiff systems, and that these methods may permit integration of much larger networks than have been feasible previously in a variety of fields.
Explicit versus implicit social cognition testing in autism spectrum disorder
Callenmark, Björn; Kjellin, Lars; Rönnqvist, Louise
2014-01-01
Although autism spectrum disorder is defined by reciprocal social-communication impairments, several studies have found no evidence for altered social cognition test performance. This study examined explicit (i.e. prompted) and implicit (i.e. spontaneous) variants of social cognition testing in autism spectrum disorder. A sample of 19 adolescents with autism spectrum disorder and 19 carefully matched typically developing controls completed the Dewey Story Test. ‘Explicit’ (multiple-choice answering format) and ‘implicit’ (free interview) measures of social cognition were obtained. Autism spectrum disorder participants did not differ from controls regarding explicit social cognition performance. However, the autism spectrum disorder group performed more poorly than controls on implicit social cognition performance in terms of spontaneous perspective taking and social awareness. Findings suggest that social cognition alterations in autism spectrum disorder are primarily implicit in nature and that an apparent absence of social cognition difficulties on certain tests using rather explicit testing formats does not necessarily mean social cognition typicality in autism spectrum disorder. PMID:24104519
Depth migration in transversely isotropic media with explicit operators
Uzcategui, Omar
1994-12-01
The author presents and analyzes three approaches to calculating explicit two-dimensional (2D) depth-extrapolation filters for all propagation modes (P, SV, and SH) in transversely isotropic media with vertical and tilted axis of symmetry. These extrapolation filters are used to do 2D poststack depth migration, and also, just as for isotropic media, these 2D filters are used in the McClellan transformation to do poststack 3D depth migration. Furthermore, the same explicit filters can also be used to do depth-extrapolation of prestack data. The explicit filters are derived by generalizations of three different approaches: the modified Taylor series, least-squares, and minimax methods initially developed for isotropic media. The examples here show that the least-squares and minimax methods produce filters with accurate extrapolation (measured in the ability to position steep reflectors) for a wider range of propagation angles than that obtained using the modified Taylor series method. However, for low propagation angles, the modified Taylor series method has smaller amplitude and phase errors than those produced by the least-squares and minimax methods. These results suggest that to get accurate amplitude estimation, modified Taylor series filters would be somewhat preferred in areas with low dips. In areas with larger dips, the least-squares and minimax methods would give a distinctly better delineation of the subsurface structures.
Implicit and explicit attitude dissociation in spontaneous deceptive behavior.
Jung, Kyu Hee; Lee, Jang-Han
2009-09-01
Society considers deception to be an improper act but at the same time, people deceive each other surprisingly often during interpersonal interactions. In our study, this hypocrisy was assumed to be derived from ambivalent attitudes stemming from different sources, which we divided into implicit and explicit. Using a simulated racing task in a virtual environment, we identified participants who chose to be deceptive. Twenty two of the 60 subjects spontaneously decided to cheat in order to gain monetary compensation, while the other 38 subjects chose to be honest. We compared these two groups' implicit beliefs about deception using the Implicit Association Test (Deception-IAT), as well as their explicit attitudes about deception and their personalities using self-report questionnaires. There was no difference between the two groups in explicit attitude or personality; however, the group who cheated on the racing task showed their implicit preference for deception more than that of the group who acted honestly as measured by the Deception-IAT.
Explicit mentalizing mechanisms and their adaptive role in memory conformity.
Wheeler, Rebecca; Allan, Kevin; Tsivilis, Dimitris; Martin, Douglas; Gabbert, Fiona
2013-01-01
Memory conformity occurs when an individual endorses what other individuals remember about past events. Research on memory conformity is currently dominated by a 'forensic' perspective, which views the phenomenon as inherently undesirable. This is because conformity not only distorts the accuracy of an individual's memory, but also produces false corroboration between individuals, effects that act to undermine criminal justice systems. There is growing awareness, however, that memory conformity may be interpreted more generally as an adaptive social behavior regulated by explicit mentalizing mechanisms. Here, we provide novel evidence in support of this emerging alternative theoretical perspective. We carried out a memory conformity experiment which revealed that explicit belief-simulation (i.e. using one's own beliefs to model what other people believe) systematically biases conformity towards like-minded individuals, even when there is no objective evidence that they have a more accurate memory than dissimilar individuals. We suggest that this bias is functional, i.e. adaptive, to the extent that it fosters trust, and hence cooperation, between in-group versus out-group individuals. We conclude that memory conformity is, in more fundamental terms, a highly desirable product of explicit mentalizing mechanisms that promote adaptive forms of social learning and cooperation.
Tepordei, V.V.
1996-01-01
Part of the Annual Commodities Review 1995. Production of construction aggregates such as crushed stone and construction sand and gravel showed a marginal increase in 1995. Most of the 1995 increases were due to funding for highway construction work. The major areas of concern to the industry included issues relating to wetlands classification and the classification of crystalline silica as a probable human carcinogen. Despite this, an increase in demand is anticipated for 1996.
Quantum mechanical force field for hydrogen fluoride with explicit electronic polarization
Mazack, Michael J. M.; Gao, Jiali
2014-05-28
The explicit polarization (X-Pol) theory is a fragment-based quantum chemical method that explicitly models the internal electronic polarization and intermolecular interactions of a chemical system. X-Pol theory provides a framework to construct a quantum mechanical force field, which we have extended to liquid hydrogen fluoride (HF) in this work. The parameterization, called XPHF, is built upon the same formalism introduced for the XP3P model of liquid water, which is based on the polarized molecular orbital (PMO) semiempirical quantum chemistry method and the dipole-preserving polarization consistent point charge model. We introduce a fluorine parameter set for PMO, and find good agreement for various gas-phase results of small HF clusters compared to experiments and ab initio calculations at the M06-2X/MG3S level of theory. In addition, the XPHF model shows reasonable agreement with experiments for a variety of structural and thermodynamic properties in the liquid state, including radial distribution functions, interaction energies, diffusion coefficients, and densities at various state points.
Explicit Hamiltonians inducing volume law for entanglement entropy in fermionic lattices
NASA Astrophysics Data System (ADS)
Gori, Giacomo; Paganelli, Simone; Sharma, Auditya; Sodano, Pasquale; Trombettoni, Andrea
2015-06-01
We show how the area law for entanglement entropy may be violated by free fermions on a lattice, and we look for conditions leading to the emergence of a volume law. We give an explicit construction of the states with maximal entanglement entropy based on the fact that, once a bipartition of the lattice in two complementary sets A and A ¯ is given, the states with maximal entanglement entropy (volume law) may be factored into Bell pairs (BPs) formed by two states with support on A and A ¯. We then exhibit, for translational invariant fermionic systems on a lattice, a Hamiltonian whose ground state is such that it yields an exact volume law. As expected, the corresponding Fermi surface has a fractal topology. We also provide some examples of fermionic models for which the ground state may have an entanglement entropy SA between the area and the volume law, building an explicit example of a one-dimensional free fermion model where SA(L ) ∝Lβ , with β being intermediate between β =0 (area law) and β =1 (BP state inducing volume law). For this model, the dispersion relation has a "zigzag" structure leading to a fractal Fermi surface whose counting box dimension equals, for large lattices, β . Our analysis clearly relates the violation of the area law for the entanglement entropy of the ground state to the emergence of a nontrivial topology of the Fermi surface.
Explicit high-order noncanonical symplectic algorithms for ideal two-fluid systems
NASA Astrophysics Data System (ADS)
Xiao, Jianyuan; Qin, Hong; Morrison, Philip J.; Liu, Jian; Yu, Zhi; Zhang, Ruili; He, Yang
2016-11-01
An explicit high-order noncanonical symplectic algorithm for ideal two-fluid systems is developed. The fluid is discretized as particles in the Lagrangian description, while the electromagnetic fields and internal energy are treated as discrete differential form fields on a fixed mesh. With the assistance of Whitney interpolating forms [H. Whitney, Geometric Integration Theory (Princeton University Press, 1957); M. Desbrun et al., Discrete Differential Geometry (Springer, 2008); J. Xiao et al., Phys. Plasmas 22, 112504 (2015)], this scheme preserves the gauge symmetry of the electromagnetic field, and the pressure field is naturally derived from the discrete internal energy. The whole system is solved using the Hamiltonian splitting method discovered by He et al. [Phys. Plasmas 22, 124503 (2015)], which was been successfully adopted in constructing symplectic particle-in-cell schemes [J. Xiao et al., Phys. Plasmas 22, 112504 (2015)]. Because of its structure preserving and explicit nature, this algorithm is especially suitable for large-scale simulations for physics problems that are multi-scale and require long-term fidelity and accuracy. The algorithm is verified via two tests: studies of the dispersion relation of waves in a two-fluid plasma system and the oscillating two-stream instability.
Locally adaptive, spatially explicit projection of US population for 2030 and 2050
McKee, Jacob J.; Rose, Amy N.; Bright, Edward A.; Huynh, Timmy; Bhaduri, Budhendra L.
2015-01-01
Localized adverse events, including natural hazards, epidemiological events, and human conflict, underscore the criticality of quantifying and mapping current population. Building on the spatial interpolation technique previously developed for high-resolution population distribution data (LandScan Global and LandScan USA), we have constructed an empirically informed spatial distribution of projected population of the contiguous United States for 2030 and 2050, depicting one of many possible population futures. Whereas most current large-scale, spatially explicit population projections typically rely on a population gravity model to determine areas of future growth, our projection model departs from these by accounting for multiple components that affect population distribution. Modeled variables, which included land cover, slope, distances to larger cities, and a moving average of current population, were locally adaptive and geographically varying. The resulting weighted surface was used to determine which areas had the greatest likelihood for future population change. Population projections of county level numbers were developed using a modified version of the US Census’s projection methodology, with the US Census’s official projection as the benchmark. Applications of our model include incorporating multiple various scenario-driven events to produce a range of spatially explicit population futures for suitability modeling, service area planning for governmental agencies, consequence assessment, mitigation planning and implementation, and assessment of spatially vulnerable populations. PMID:25605882
Quantum mechanical force field for hydrogen fluoride with explicit electronic polarization.
Mazack, Michael J M; Gao, Jiali
2014-05-28
The explicit polarization (X-Pol) theory is a fragment-based quantum chemical method that explicitly models the internal electronic polarization and intermolecular interactions of a chemical system. X-Pol theory provides a framework to construct a quantum mechanical force field, which we have extended to liquid hydrogen fluoride (HF) in this work. The parameterization, called XPHF, is built upon the same formalism introduced for the XP3P model of liquid water, which is based on the polarized molecular orbital (PMO) semiempirical quantum chemistry method and the dipole-preserving polarization consistent point charge model. We introduce a fluorine parameter set for PMO, and find good agreement for various gas-phase results of small HF clusters compared to experiments and ab initio calculations at the M06-2X/MG3S level of theory. In addition, the XPHF model shows reasonable agreement with experiments for a variety of structural and thermodynamic properties in the liquid state, including radial distribution functions, interaction energies, diffusion coefficients, and densities at various state points.
Quantum mechanical force field for hydrogen fluoride with explicit electronic polarization
Mazack, Michael J. M.; Gao, Jiali
2014-01-01
The explicit polarization (X-Pol) theory is a fragment-based quantum chemical method that explicitly models the internal electronic polarization and intermolecular interactions of a chemical system. X-Pol theory provides a framework to construct a quantum mechanical force field, which we have extended to liquid hydrogen fluoride (HF) in this work. The parameterization, called XPHF, is built upon the same formalism introduced for the XP3P model of liquid water, which is based on the polarized molecular orbital (PMO) semiempirical quantum chemistry method and the dipole-preserving polarization consistent point charge model. We introduce a fluorine parameter set for PMO, and find good agreement for various gas-phase results of small HF clusters compared to experiments and ab initio calculations at the M06-2X/MG3S level of theory. In addition, the XPHF model shows reasonable agreement with experiments for a variety of structural and thermodynamic properties in the liquid state, including radial distribution functions, interaction energies, diffusion coefficients, and densities at various state points. PMID:24880295
ERIC Educational Resources Information Center
Simanek, Donald E.
1994-01-01
Compares and reviews currently available brands of steel construction sets that are useful to physics teachers for building demonstrations, prototypes of mechanisms, robotics, and remote control devices. (ZWH)
Explicit solutions for effective four- and five-loop QCD running coupling
NASA Astrophysics Data System (ADS)
Cvetič, Gorazd; Kondrashuk, Igor
2011-12-01
We start with the explicit solution, in terms of the Lambert W function, of the renormalization group equation (RGE) for the gauge coupling in the supersymmetric Yang-Mills theory described by the well-known NSVZ β-function. We then construct a class of β-functions for which the RGE can be solved in terms of the Lambert W function. These β-functions are expressed in terms of a function which is a truncated Laurent series in the inverse u of the gauge coupling a ≡ α/π. The parameters in the Laurent series can be adjusted so that the first coefficients of the Taylor expansion of the β-function in the gauge coupling a reproduce the four-loop or five-loop QCD (or SQCD) β-function.
NASA Astrophysics Data System (ADS)
Craven, John A., III; Hand, Brian; Prain, Vaughan
2002-08-01
This paper reports on the processes and outcomes of practices in a preservice, elementary science methods course designed to: (1) fathom existing student perceptions of the nature of science and (2) move students from holding individually constructed, typically limited views on the nature of science towards more rich, publicly negotiated views. In the course of 15 weeks, 27 preservice elementary students engaged in a series of individual and collaborative exercises that required them to explore their tacit and explicit knowledge about the nature of science. The data were analysed using the interpretative-descriptive approach. Analyses revealed notable, positive changes in the language students used to describe both the nature and structure of the scientific enterprise. The findings of this study support continued efforts in the search for ways of understanding and affecting the views of science that preservice elementary teachers typically hold.
Souhrada, L
1991-02-20
The deepening recession hasn't slowed hospital construction activity--at least not yet. While experts say health care executives should expect fewer large projects within the next two years, as the result of unpredictable sources of capital and increasing censure of hospital capital spending, for the moment hospital projects are helping to shelter some design and construction firms from the recession's fallout.
NASA Astrophysics Data System (ADS)
Rocha, L. F. O.; Silva, I. R.; Caliri, A.
2009-10-01
In the protein folding problem, solvent-mediated forces are commonly represented by intra-chain pairwise contact energy. Although this approximation has proven to be useful in several circumstances, it is limited in some other aspects of the problem. Here we show that it is possible to achieve two models to represent the chain-solvent system, one of them with implicit and other with explicit solvent, such that both reproduce the same thermodynamic results. Firstly, lattice models treated by analytical methods, were used to show that the implicit and explicitly representation of solvent effects can be energetically equivalent only if local solvent properties are time and spatially invariant. Following, applying the same reasoning used for the lattice models, two inter-consistent Monte Carlo off-lattice models for implicit and explicit solvent are constructed, being that now in the latter the solvent properties are allowed to fluctuate. Then, it is shown that the chain configurational evolution as well as the globule equilibrium conformation are significantly distinct for implicit and explicit solvent systems. Actually, strongly contrasting with the implicit solvent version, the explicit solvent model predicts: (i) a malleable globule, in agreement with the estimated large protein-volume fluctuations; (ii) thermal conformational stability, resembling the conformational heat resistance of globular proteins, in which radii of gyration are practically insensitive to thermal effects over a relatively wide range of temperatures; and (iii) smaller radii of gyration at higher temperatures, indicating that the chain conformational entropy in the unfolded state is significantly smaller than that estimated from random coil configurations. Finally, we comment on the meaning of these results with respect to the understanding of the folding process.
Explicit solution of the Lindblad equation for nearly isotropic boundary driven XY spin 1/2 chain
NASA Astrophysics Data System (ADS)
Žunkovič, Bojan; Prosen, Tomaž
2010-08-01
Explicit solution for the two-point correlation function in a non-equilibrium steady state of a nearly isotropic boundary driven open XY spin 1/2 chain in the Lindblad formulation is provided. A non-equilibrium quantum phase transition from exponentially decaying correlations to long range order is discussed analytically. In the regime of long range order a new phenomenon of correlation resonances is reported, where the correlation response of the system is unusually high for certain discrete values of the external bulk parameter, e.g. the magnetic field.
Integrating remote sensing and spatially explicit epidemiological modeling
NASA Astrophysics Data System (ADS)
Finger, Flavio; Knox, Allyn; Bertuzzo, Enrico; Mari, Lorenzo; Bompangue, Didier; Gatto, Marino; Rinaldo, Andrea
2015-04-01
Spatially explicit epidemiological models are a crucial tool for the prediction of epidemiological patterns in time and space as well as for the allocation of health care resources. In addition they can provide valuable information about epidemiological processes and allow for the identification of environmental drivers of the disease spread. Most epidemiological models rely on environmental data as inputs. They can either be measured in the field by the means of conventional instruments or using remote sensing techniques to measure suitable proxies of the variables of interest. The later benefit from several advantages over conventional methods, including data availability, which can be an issue especially in developing, and spatial as well as temporal resolution of the data, which is particularly crucial for spatially explicit models. Here we present the case study of a spatially explicit, semi-mechanistic model applied to recurring cholera outbreaks in the Lake Kivu area (Democratic Republic of the Congo). The model describes the cholera incidence in eight health zones on the shore of the lake. Remotely sensed datasets of chlorophyll a concentration in the lake, precipitation and indices of global climate anomalies are used as environmental drivers. Human mobility and its effect on the disease spread is also taken into account. Several model configurations are tested on a data set of reported cases. The best models, accounting for different environmental drivers, and selected using the Akaike information criterion, are formally compared via cross validation. The best performing model accounts for seasonality, El Niño Southern Oscillation, precipitation and human mobility.
Lattice Boltzmann Explicit Schemes for 3D MHD on Non-Uniform Grids
NASA Astrophysics Data System (ADS)
Schleif, C.; Vahala, G.; Vahala, L.; Macnab, A.; Soe, M.; Carter, J.
2004-11-01
Lattice-Boltzmann Model (LBM) is a very promising alternative computational approach to MHD and to other nonlinear macroscopic systems because of its simplicity, ease of imposition of geometric boundary conditions and ideal parallelization on multi-PE (and especially vector) platforms. For example, on the Earth Simulator our 2D explicit LBM-MHD code has achieved over 3.6 TFlops/sec. The disparate length and time scales that appear in the solutions of dissipative MHD require careful treatment of ill-conditioned matrices in direct solvers. In LBM-MHD one introduces a scalar distribution function for the velocity field and a vector distribution function for the magnetic field. Since the magnetic evolution equation is obtained at the 1st moment closures, less speeds are needed than to recover the momentum equation. We are also investigating the least square LBM for non-uniform spatial grids. In one approach, the standard LBM is applied to the fine scales while the least square LBM is applied to the large scales. Since the least square algorithm involves matrices that are only grid-dependent, these matrices need only be calculated once leading to an efficient algorithm. Our algorithm will be applied to the 3D Orszag-Tang vortex and compare our results to the 3D pseudo-spectral results of Poquet et. al.
Assessment of an Explicit Algebraic Reynolds Stress Model
NASA Technical Reports Server (NTRS)
Carlson, Jan-Renee
2005-01-01
This study assesses an explicit algebraic Reynolds stress turbulence model in the in the three-dimensional Reynolds averaged Navier-Stokes (RANS) solver, ISAAC (Integrated Solution Algorithm for Arbitrary Con gurations). Additionally, it compares solutions for two select configurations between ISAAC and the RANS solver PAB3D. This study compares with either direct numerical simulation data, experimental data, or empirical models for several different geometries with compressible, separated, and high Reynolds number flows. In general, the turbulence model matched data or followed experimental trends well, and for the selected configurations, the computational results of ISAAC closely matched those of PAB3D using the same turbulence model.
Controlling of explicit internal signal stochastic resonance by external signal
NASA Astrophysics Data System (ADS)
Li, Ya Ping; Wang, Pin; Li, Qian Shu
2004-09-01
Explicit internal signal stochastic resonance (EISSR) is investigated in a model of energy transduction of molecular machinery when noise is added to the region of oscillation in the presence of external signal (ES). It is found that EISSR could be controlled, i.e., enhanced or suppressed by adjusting frequency (ωe) and amplitude (A) of ES, and that there exits an optimal frequency for ES, which makes EISSR strength reach the maximum. Meanwhile, a critical amplitude (Ac) is found, which is a threshold of occurrence of EISSR. Finally, the difference and similarity between EISSR and IISSR (implicit internal signal stochastic resonance) are discussed.
An explicit mixed numerical method for mesoscale model
NASA Technical Reports Server (NTRS)
Hsu, H.-M.
1981-01-01
A mixed numerical method has been developed for mesoscale models. The technique consists of a forward difference scheme for time tendency terms, an upstream scheme for advective terms, and a central scheme for the other terms in a physical system. It is shown that the mixed method is conditionally stable and highly accurate for approximating the system of either shallow-water equations in one dimension or primitive equations in three dimensions. Since the technique is explicit and two time level, it conserves computer and programming resources.
Immediate IPTV channel leave by explicit user tracking in PON
NASA Astrophysics Data System (ADS)
Zhu, Peng; Yoshiuchi, Hideya; Yoshizawa, Satoshi
2007-11-01
In this paper, we propose a novel IPTV channel leave mechanism for Passive Optical Network (PON). By explicit user tracking and automatic differentiation of IGMP v2 and v3 users, the proposed mechanism can realize immediate channel leave in both Optical Line Terminal (OLT) and Optical Network Unit (ONU) while avoiding removing the channel which still has users. Simulation results show that the proposed mechanism can significantly save the bandwidth consumption during "channel surf" by users, compared to the standard IGMP timeout mechanism.
Explicit Krawtchouk moment invariants for invariant image recognition
NASA Astrophysics Data System (ADS)
Xiao, Bin; Zhang, Yanhong; Li, Linping; Li, Weisheng; Wang, Guoyin
2016-03-01
The existing Krawtchouk moment invariants are derived by a linear combination of geometric moment invariants. This indirect method cannot achieve perfect performance in rotation, scale, and translation (RST) invariant image recognition since the derivation of these invariants are not built on Krawtchouk polynomials. A direct method to derive RST invariants from Krawtchouk moments, named explicit Krawtchouk moment invariants, is proposed. The proposed method drives Krawtchouk moment invariants by algebraically eliminating the distorted (i.e., rotated, scaled, and translated) factor contained in the Krawtchouk moments of distorted image. Experimental results show that, compared with the indirect methods, the proposed approach can significantly improve the performance in terms of recognition accuracy and noise robustness.
The impact of fluency on explicit memory tasks in amnesia.
Hayes, Scott M; Verfaellie, Mieke
2012-01-01
Abstract Distinguishing implicit and explicit memory and delineating their relationship has haunted memory researchers for decades, and Voss et al. provide an impressive overview of their work examining these issues. We briefly comment on the following: (1) There is evidence indicating that implicit memory impacts cued recall, in addition to recognition; (2) Fluency can manifest as priming in implicit memory or it can be experienced as familiarity (in association with attribution processes) in recognition tasks; and (3) The impact of fluency on accuracy of "guess" responses during recognition memory in normal subjects is reminiscent of similar effects on recognition in amnesia.
Improving Explicit Congestion Notification with the Mark-Front Strategy
NASA Technical Reports Server (NTRS)
Liu, Chunlei; Jain, Raj
2001-01-01
Delivering congestion signals is essential to the performance of networks. Current TCP/IP networks use packet losses to signal congestion. Packet losses not only reduces TCP performance, but also adds large delay. Explicit Congestion Notification (ECN) delivers a faster indication of congestion and has better performance. However, current ECN implementations mark the packet from the tail of the queue. In this paper, we propose the mark-front strategy to send an even faster congestion signal. We show that mark-front strategy reduces buffer size requirement, improves link efficiency and provides better fairness among users. Simulation results that verify our analysis are also presented.
Predicting dislocation climb and creep from explicit atomistic details.
Kabir, Mukul; Lau, Timothy T; Rodney, David; Yip, Sidney; Van Vliet, Krystyn J
2010-08-27
Here we report kinetic Monte Carlo simulations of dislocation climb in heavily deformed, body-centered cubic iron comprising a supersaturation of vacancies. This approach explicitly incorporates the effect of nonlinear vacancy-dislocation interaction on vacancy migration barriers as determined from atomistic calculations, and enables observations of diffusivity and climb over time scales and temperatures relevant to power-law creep. By capturing the underlying microscopic physics, the calculated stress exponents for steady-state creep rates agree quantitatively with the experimentally measured range, and qualitatively with the stress dependence of creep activation energies.
Explicit Pore Pressure Material Model in Carbon-Cloth Phenolic
NASA Technical Reports Server (NTRS)
Gutierrez-Lemini, Danton; Ehle, Curt
2003-01-01
An explicit material model that uses predicted pressure in the pores of a carbon-cloth phenolic (CCP) composite has been developed. This model is intended to be used within a finite-element model to predict phenomena specific to CCP components of solid-fuel-rocket nozzles subjected to high operating temperatures and to mechanical stresses that can be great enough to cause structural failures. Phenomena that can be predicted with the help of this model include failures of specimens in restrained-thermal-growth (RTG) tests, pocketing erosion, and ply lifting
Direct folding simulation of a long helix in explicit water
NASA Astrophysics Data System (ADS)
Gao, Ya; Lu, Xiaoliang; Duan, Lili; Zhang, Dawei; Mei, Ye; Zhang, John Z. H.
2013-05-01
A recently proposed Polarizable Hydrogen Bond (PHB) method has been employed to simulate the folding of a 53 amino acid helix (PDB ID 2KHK) in explicit water. Under PHB simulation, starting from a fully extended structure, the peptide folds into the native state as confirmed by measured time evolutions of radius of gyration, root mean square deviation (RMSD), and native hydrogen bond. Free energy and cluster analysis show that the folded helix is thermally stable under the PHB model. Comparison of simulation results under, respectively, PHB and standard nonpolarizable force field demonstrates that polarization is critical for stable folding of this long α-helix.
Explicit estimates in the Bramson-Kalikow model
NASA Astrophysics Data System (ADS)
C, Gallesco; S, Gallo; Y, Takahashi D.
2014-09-01
The aim of this paper is to explicitly compute parameters for which the Bramson-Kalikow (BK) model exhibits phase transition. The main ingredient of the proof is a simple new criterion for non-uniqueness of g-measures. We show that the existence of multiple g-measures compatible with a function g can be proved by estimating the \\bar{d} -distances between some suitably chosen Markov chains. The method is optimal for the important class of binary regular attractive kernels, which includes the BK model.
EXPLICT CALULATIONS OF HOMOCLINIC TANGLES SURROUNDING MAGNETIC ISLANDS IN TOKAMAKS
ROEDER, R.K.W.; RAPOPORT, B.I.; EVANS, T.E.
2002-06-01
We present explicit calculations of the complicated geometric objects known as homoclinic tangles that surround magnetic islands in the Poincare mapping of a tokamak's magnetic field. These tangles are shown to exist generically in the magnetic field of all toroidal confinement systems. The geometry of these tangles provides an explanation for the stochasticity known to occur near the X-points of the Poincare mapping. Furthermore, the intersection of homoclinic tangles from different resonances provides an explicit mechanism for the non-diffusive transport of magnetic field lines between these resonance layers.
Pre-gilbertian conceptions of terrestrial magnetism
Smith, P.J.
1968-01-01
It is now well known that William Gilbert, in his De Magnete of 1600, first suggested that the earth behaves as a great magnet. By their very nature, however, such explicit statements tend, in retrospect, to be emphasised at the expense of less explicit antecedent ideas and experiments, with the result that, in the example under consideration here, the impression has sometimes been given that before Gilbert there was not the slightest suspicion that the earth exerts influence on the magnetic needle. In fact, Gilbert's conclusion represented the culmination of many centuries of thought and experimentation on the subject. This essay traces the main steps in the evolutionary process from the idea that magnetic 'virtue' derived from the heave, through the gradual realisation that magnetism is closely associated with the earth, up to the time of Gilbert's definite statement. ?? 1968.
Magnet Trade Books: Attracting and Repelling Concepts
ERIC Educational Resources Information Center
Barrow, Lloyd H.; Robinson, Richard D.
2007-01-01
A series of magnet trade books were analyzed against a validated list of magnet concepts (Barrow, 1990a) and their Flesch (1974) Readability was determined. These trade books were used to supplement a second grade unit on magnetism locally constructed from AIM's "Mostly Magnets" (1991). All trade books accurately described how like and unlike…
ERIC Educational Resources Information Center
Bilardello, Nicholas; Valdes, Linda
1998-01-01
Introduces a method for constructing phylogenies using molecular traits and elementary graph theory. Discusses analyzing molecular data and using weighted graphs, minimum-weight spanning trees, and rooted cube phylogenies to display the data. (DDR)
ERIC Educational Resources Information Center
Barley, John McKim, II
1986-01-01
Successful completion of a construction project requires the efforts of a team composed of the owner, architect, and contractor. A preconstruction conference can clarify the roles of the team as specified in the design contract. (MLF)
Explicit simulation of a midlatitude Mesoscale Convective System
Alexander, G.D.; Cotton, W.R.
1996-04-01
We have explicitly simulated the mesoscale convective system (MCS) observed on 23-24 June 1985 during PRE-STORM, the Preliminary Regional Experiment for the Stormscale Operational and Research and Meterology Program. Stensrud and Maddox (1988), Johnson and Bartels (1992), and Bernstein and Johnson (1994) are among the researchers who have investigated various aspects of this MCS event. We have performed this MCS simulation (and a similar one of a tropical MCS; Alexander and Cotton 1994) in the spirit of the Global Energy and Water Cycle Experiment Cloud Systems Study (GCSS), in which cloud-resolving models are used to assist in the formulation and testing of cloud parameterization schemes for larger-scale models. In this paper, we describe (1) the nature of our 23-24 June MCS dimulation and (2) our efforts to date in using our explicit MCS simulations to assist in the development of a GCM parameterization for mesoscale flow branches. The paper is organized as follows. First, we discuss the synoptic situation surrounding the 23-24 June PRE-STORM MCS followed by a discussion of the model setup and results of our simulation. We then discuss the use of our MCS simulation. We then discuss the use of our MCS simulations in developing a GCM parameterization for mesoscale flow branches and summarize our results.
A spatially explicit Bayesian framework for cognitive schooling behaviours
Grünbaum, Daniel
2012-01-01
Social aggregations such as schools, swarms, flocks and herds occur across a broad diversity of animal species, strongly impacting ecological and evolutionary dynamics of these species and their predators, prey and competitors. The mechanisms through which individual-level responses to neighbours generate group-level characteristics have been extensively investigated both experimentally and using mathematical models. Models of social groups typically adopt a ‘zone’ approach, in which individuals’ movement responses to neighbours are functions of instantaneous relative position. Empirical studies have demonstrated that most social animals such as fish exhibit well-developed spatial memory and other advanced cognitive capabilities. However, most models of social grouping do not explicitly include spatial memory, largely because a tractable framework for modelling acquisition of and response to historical spatial information has been lacking. Using fish schooling as a focal example, this study presents a framework for including cognitive responses to spatial memory in models of social aggregation. The framework utilizes Bayesian estimation parameters that are continuously distributed in time and space as proxies for animals’ spatial memory. The result is a hybrid Lagrangian–Eulerian model in which the effects of cognitive state and behavioural responses to historical spatial data on individual-, group- and population-level distributions of social animals can be explicitly investigated. PMID:24312727
Aerosol activation: parameterised versus explicit calculation for global models
NASA Astrophysics Data System (ADS)
Tost, H.; Pringle, K.; Metzger, S.; Lelieveld, J.
2009-04-01
A key process in studies of the aerosol indirect effects on clouds is the activation of particles into droplets at 100% relative humidity. To model this process in cloud, meteorological and climate models is a difficult undertaking because of the wide range of scales involved. The chemical composition of the atmospheric aerosol, originating from both air pollution and natural sources, substantially impacts the aerosol water uptake and growth due to its hygroscopicity. In this study a comparison of aerosol activation, using state-of-the-art aerosol activation parameterisations, and explicit activation due to hygroscopic growth is performed.For that purpose we apply the GMXe aerosol model - treating both dynamic and thermodynamic aerosol properties - within the EMAC (ECHAM5/MESSy Atmospheric chemistry, an atmospheric chemistry general circulation) model. This new aerosol model can explicitely calculate the water uptake of aerosols due to hygroscopicity, allowing the growth of aerosol particles into the regimes of cloud droplets in case of sufficient water vapour availability. Global model simulations using both activation schemes will be presented and compared, elucidating the advantages of each approach.
Explicitly correlated ring-coupled-cluster-doubles theory
Hehn, Anna-Sophia; Klopper, Wim; Tew, David P.
2015-05-21
The connection between the random-phase approximation and the ring-coupled-cluster-doubles method bridges the gap between density-functional and wave-function theories and the importance of the random-phase approximation lies in both its broad applicability and this linking role in electronic-structure theory. In this contribution, we present an explicitly correlated approach to the random-phase approximation, based on the direct ring-coupled-cluster-doubles ansatz, which overcomes the problem of slow basis-set convergence, inherent to the random-phase approximation. Benchmark results for a test set of 106 molecules and a selection of 10 organic complexes from the S22 test set demonstrate that convergence to within 99% of the basis-set limit is reached for triple-zeta basis sets for atomisation energies, while quadruple-zeta basis sets are required for interaction energies. Corrections due to single excitations into the complementary auxiliary space reduce the basis-set incompleteness error by one order of magnitude, while contributions due to the coupling of conventional and geminal amplitudes are in general negligible. We find that a non-iterative explicitly correlated correction to first order in perturbation theory exhibits the best ratio of accuracy to computational cost.
Explicit analytic formulas for Newtonian Taylor-Couette primary instabilities.
Dutcher, C S; Muller, S J
2007-04-01
In this study, existing primary stability boundary data for flow between concentric cylinders, for the broad range of radius and rotation ratios examined, were found to be self-similar in a properly chosen parameter space. The experimental results for the primary transitions to both Taylor vortex flow and spiral vortex flow collapsed onto a single curve using a combination of variables technique, for both counter-rotating and co-rotating cylinders. The curves were then empirically fit, yielding explicit analytic formulas for the critical Reynolds number for any radius ratio (eta) and rotation ratio (micro) . For counter-rotating flows, the primary critical Reynolds number is determined by a single variable: the ratio of the nodal gap fraction to a known function of the radius ratio. The existence and influence of a nodal surface is shown experimentally for micro approximately equal -1.7. For co-rotating flows, the important scaled variable was found to be the radius ratio divided by the nodal radius ratio. Comparisons of the resulting explicit stability formulas were made to existing analytic stability expressions and experimental data. Excellent quantitative agreement was found with data across the entire parameter space.
Implicit and Explicit Categorization: A Tale of Four Species
Smith, J. David; Berg, Mark E.; Cook, Robert G.; Murphy, Matthew S.; Crossley, Matthew J.; Boomer, Joe; Spiering, Brian; Beran, Michael J.; Church, Barbara A.; Ashby, F. Gregory; Grace, Randolph C.
2013-01-01
Categorization is essential for survival, and it is a widely studied cognitive adaptation in humans and animals. An influential neuroscience perspective differentiates in humans an explicit, rule-based categorization system from an implicit system that slowly associates response outputs to different regions of perceptual space. This perspective is being extended to study categorization in other vertebrate species, using category tasks that have a one-dimensional, rule-based solution or a two-dimensional, information-integration solution. Humans, macaques, and capuchin monkeys strongly dimensionalize perceptual stimuli and learn rule-based tasks more quickly. In sharp contrast, pigeons learn these two tasks equally quickly. Pigeons represent a cognitive system in which the commitment to dimensional analysis and category rules was not strongly made. Their results may reveal the character of the ancestral vertebrate categorization system from which that of primates emerged. The primate results establish continuity with human cognition, suggesting that nonhuman primates share aspects of humans' capacity for explicit cognition. The emergence of dimensional analysis and rule learning could have been an important step in primates' cognitive evolution. PMID:22981878
Development of appropriateness explicit criteria for cataract extraction by phacoemulsification
Ma Quintana, José; Escobar, Antonio; Aróstegui, Inmaculada
2006-01-01
Background Consensus development techniques were used in the late 1980s to create explicit criteria for the appropriateness of cataract extraction. We developed a new appropriateness of indications tool for cataract following the RAND method. We tested the validity of our panel results. Methods Criteria were developed using a modified Delphi panel judgment process. A panel of 12 ophthalmologists was assembled. Ratings were analyzed regarding the level of agreement among panelists. We studied the influence of all variables on the final panel score using linear and logistic regression models. The explicit criteria developed were summarized by classification and regression tree analysis. Results Of the 765 indications evaluated by the main panel in the second round, 32.9% were found appropriate, 30.1% uncertain, and 37% inappropriate. Agreement was found in 53% of the indications and disagreement in 0.9%. Seven variables were considered to create the indications and divided into three groups: simple cataract, with diabetic retinopathy, or with other ocular pathologies. The preoperative visual acuity in the cataractous eye and visual function were the variables that best explained the panel scoring. The panel results were synthesized and presented in three decision trees. Misclassification error in the decision trees, as compared with the panel original criteria, was 5.3%. Conclusion The parameters tested showed acceptable validity for an evaluation tool. These results support the use of this indication algorithm as a screening tool for assessing the appropriateness of cataract extraction in field studies and for the development of practice guidelines. PMID:16512906
Explicit analytic equations for multimolecular thermal melting curves.
Böttcher, Albrecht; Kowerko, Danny; Sigel, Roland K O
2015-07-01
The analysis of thermal melting curves requires the knowledge of equations for the temperature dependence of the relative fraction of folded and unfolded components. To implement these equations as standard tools for curve fitting, they should be as explicit as possible. From the van't Hoff formalism it is known that the equilibrium constant and hence the folded fraction is a function of the absolute temperature, the van't Hoff transition enthalpy, and the melting temperature. The work presented here is devoted to the mathematically self-contained derivation and the listing of explicit equations for the folded fraction as a function of the thermodynamic parameters in the case of arbitrary molecularities. Part of the results are known, others are new. It is in particular shown for the first time that the folded fraction is the composition of a universal function which depends solely on the molecularity and a dimensionless function which is governed by the concrete thermodynamic regime but is independent of the molecularity. The results will prove useful for extracting the thermodynamic parameters from experimental data on the basis of regression analysis. As supporting information, open-source Matlab scripts for the computer implementation of the equations are provided.
Super-resolution without explicit subpixel motion estimation.
Takeda, Hiroyuki; Milanfar, Peyman; Protter, Matan; Elad, Michael
2009-09-01
The need for precise (subpixel accuracy) motion estimates in conventional super-resolution has limited its applicability to only video sequences with relatively simple motions such as global translational or affine displacements. In this paper, we introduce a novel framework for adaptive enhancement and spatiotemporal upscaling of videos containing complex activities without explicit need for accurate motion estimation. Our approach is based on multidimensional kernel regression, where each pixel in the video sequence is approximated with a 3-D local (Taylor) series, capturing the essential local behavior of its spatiotemporal neighborhood. The coefficients of this series are estimated by solving a local weighted least-squares problem, where the weights are a function of the 3-D space-time orientation in the neighborhood. As this framework is fundamentally based upon the comparison of neighboring pixels in both space and time, it implicitly contains information about the local motion of the pixels across time, therefore rendering unnecessary an explicit computation of motions of modest size. The proposed approach not only significantly widens the applicability of super-resolution methods to a broad variety of video sequences containing complex motions, but also yields improved overall performance. Using several examples, we illustrate that the developed algorithm has super-resolution capabilities that provide improved optical resolution in the output, while being able to work on general input video with essentially arbitrary motion.
Cognitive conflict without explicit conflict monitoring in a dynamical agent.
Ward, Robert; Ward, Ronnie
2006-11-01
We examine mechanisms for resolving cognitive conflict in an embodied, situated, and dynamic agent, developed through an evolutionary learning process. The agent was required to solve problems of response conflict in a dual-target "catching" task, focusing response on one of the targets while ignoring the other. Conflict in the agent was revealed at the behavioral level in terms of increased latencies to the second target. This behavioral interference was correlated to peak violations of the network's stable state equation. At the level of the agent's neural network, peak violations were also correlated to periods of disagreement in source inputs to the agent's motor effectors. Despite observing conflict at these numerous levels, we did not find any explicit conflict monitoring mechanisms within the agent. We instead found evidence of a distributed conflict management system, characterized by competitive sources within the network. In contrast to the conflict monitoring hypothesis [Botvinick, M. M., Braver, T. S., Barch, D. M., Carter, C. S., & Cohen, J. D. (2001). Conflict monitoring and cognitive control. Psychological Review, 108(3), 624-652], this agent demonstrates that resolution of cognitive conflict does not require explicit conflict monitoring. We consider the implications of our results for the conflict monitoring hypothesis.
Differential Age Effects for Implicit and Explicit Conceptual Associative Memory
Dew, Ilana T. Z.; Giovanello, Kelly S.
2010-01-01
Older adults show disproportionate declines in explicit memory for associative relative to item information. However, the source of these declines is still uncertain. One explanation is a generalized impairment in the processing of associative information. A second explanation is a more specialized impairment in the strategic, effortful recollection of associative information, leaving less effortful forms of associative retrieval preserved. Assessing implicit memory of new associations is a way to distinguish between these viewpoints. To date, mixed findings have emerged from studies of associative priming in aging. One factor that may account for the variability is whether the manipulations inadvertently involve strategic, explicit processes. In 2 experiments we present a novel paradigm of conceptual associative priming in which subjects make speeded associative judgments about unrelated objects. Using a size classification task, Experiment 1 showed equivalent associative priming between young and older adults. Experiment 2 generalized the results of Experiment 1 to an inside/outside classification task, while replicating the typical age-related impairment in associative but not item recognition. Taken together, the findings support the viewpoint that older adults can incidentally encode and retrieve new meaningful associations despite difficulty with the intentional recollection of the same information. PMID:21077717
Explicit integration of Friedmann's equation with nonlinear equations of state
Chen, Shouxin; Gibbons, Gary W.; Yang, Yisong E-mail: gwg1@damtp.cam.ac.uk
2015-05-01
In this paper we study the integrability of the Friedmann equations, when the equation of state for the perfect-fluid universe is nonlinear, in the light of the Chebyshev theorem. A series of important, yet not previously touched, problems will be worked out which include the generalized Chaplygin gas, two-term energy density, trinomial Friedmann, Born-Infeld, two-fluid models, and Chern-Simons modified gravity theory models. With the explicit integration, we are able to understand exactly the roles of the physical parameters in various models play in the cosmological evolution which may also offer clues to a profound understanding of the problems in general settings. For example, in the Chaplygin gas universe, a few integrable cases lead us to derive a universal formula for the asymptotic exponential growth rate of the scale factor, of an explicit form, whether the Friedmann equation is integrable or not, which reveals the coupled roles played by various physical sectors and it is seen that, as far as there is a tiny presence of nonlinear matter, conventional linear matter makes contribution to the dark matter, which becomes significant near the phantom divide line. The Friedmann equations also arise in areas of physics not directly related to cosmology. We provide some examples ranging from geometric optics and central orbits to soap films and the shape of glaciated valleys to which our results may be applied.
Logistic Mixed Models to Investigate Implicit and Explicit Belief Tracking
Lages, Martin; Scheel, Anne
2016-01-01
We investigated the proposition of a two-systems Theory of Mind in adults’ belief tracking. A sample of N = 45 participants predicted the choice of one of two opponent players after observing several rounds in an animated card game. Three matches of this card game were played and initial gaze direction on target and subsequent choice predictions were recorded for each belief task and participant. We conducted logistic regressions with mixed effects on the binary data and developed Bayesian logistic mixed models to infer implicit and explicit mentalizing in true belief and false belief tasks. Although logistic regressions with mixed effects predicted the data well a Bayesian logistic mixed model with latent task- and subject-specific parameters gave a better account of the data. As expected explicit choice predictions suggested a clear understanding of true and false beliefs (TB/FB). Surprisingly, however, model parameters for initial gaze direction also indicated belief tracking. We discuss why task-specific parameters for initial gaze directions are different from choice predictions yet reflect second-order perspective taking. PMID:27853440
Constrained Unfolding of a Helical Peptide: Implicit versus Explicit Solvents.
Bureau, Hailey R; Merz, Dale R; Hershkovits, Eli; Quirk, Stephen; Hernandez, Rigoberto
2015-01-01
Steered Molecular Dynamics (SMD) has been seen to provide the potential of mean force (PMF) along a peptide unfolding pathway effectively but at significant computational cost, particularly in all-atom solvents. Adaptive steered molecular dynamics (ASMD) has been seen to provide a significant computational advantage by limiting the spread of the trajectories in a staged approach. The contraction of the trajectories at the end of each stage can be performed by taking a structure whose nonequilibrium work is closest to the Jarzynski average (in naive ASMD) or by relaxing the trajectories under a no-work condition (in full-relaxation ASMD--namely, FR-ASMD). Both approaches have been used to determine the energetics and hydrogen-bonding structure along the pathway for unfolding of a benchmark peptide initially constrained as an α-helix in a water environment. The energetics are quite different to those in vacuum, but are found to be similar between implicit and explicit solvents. Surprisingly, the hydrogen-bonding pathways are also similar in the implicit and explicit solvents despite the fact that the solvent contact plays an important role in opening the helix.
Distinguishing three levels in explicit self-awareness.
Legrain, L; Cleeremans, A; Destrebecqz, A
2011-09-01
This paper focuses on the development of explicit self-awareness in children. Mirror self-recognition has been the most popular paradigm used to assess this ability in children. Nevertheless, according to Rochat (2003), there are, at least, three different levels of explicit self-awareness. We therefore designed three different self-recognition tasks, each corresponding to one of these levels (a mirror self-recognition task, a picture self-recognition task and a masked self-recognition task). We observed a decrease in performance across the three tasks. This supports a developmental scale in self-awareness. Besides, the masked self-recognition performance makes it possible to assess the final and the most sophisticated level of self-awareness, i.e. the external self. To our best knowledge, this task is the first attempt to evaluate the external self in preverbal children. Our results indicate that 22-month old children show awareness of their external self or, at least, that this ability is in the process of being acquired.
Simulations of peptide-graphene interactions in explicit water.
Camden, Aerial N; Barr, Stephen A; Berry, Rajiv J
2013-09-19
The interaction of graphene with biomolecules has a variety of useful applications. In particular, graphitic surfaces decorated with peptides are being considered for high performance biochemical sensors. The interaction of peptides with graphene can also provide insight into the binding behavior of larger biomolecules. In this investigation, we have computed the binding enthalpies of a series of GXG tripeptides with graphene using classical molecular dynamics. Explicit water molecules were included to capture the effect of solvent. Of the twenty amino acid residues examined (X in GXG), arginine, glutamine, and asparagine exhibit the strongest interactions with graphene. Analysis of the trajectories shows that the presence of graphene affects the peptide conformation relative to its conformation in solution. We also find that the peptides favor the graphene interface predominantly due to the influence of the solvent, with hydrophilic residues binding more strongly than hydrophobic residues. These results demonstrate the need to include explicit solvent atoms when modeling peptide-graphene systems to mimic experimental conditions. Furthermore, the scheme outlined herein may be widely applicable for the determination and validation of surface interaction parameters for a host of molecular fragments using a variety of techniques, ranging from coarse-grained models to quantum mechanical methods.
2014-01-01
The tyrosine kinase A (TrkA) receptor is a validated therapeutic intervention point for a wide range of conditions. TrkA activation by nerve growth factor (NGF) binding the second extracellular immunoglobulin (TrkAIg2) domain triggers intracellular signaling cascades. In the periphery, this promotes the pain phenotype and, in the brain, cell survival or differentiation. Reproducible structural information and detailed validation of protein–ligand interactions aid drug discovery. However, the isolated TrkAIg2 domain crystallizes as a β-strand-swapped dimer in the absence of NGF, occluding the binding surface. Here we report the design and structural validation by nuclear magnetic resonance spectroscopy of the first stable, biologically active construct of the TrkAIg2 domain for binding site confirmation. Our structure closely mimics the wild-type fold of TrkAIg2 in complex with NGF (1WWW.pdb), and the 1H–15N correlation spectra confirm that both NGF and a competing small molecule interact at the known binding interface in solution. PMID:25454499
Nelson, T.I.; Bolen, W.P.
2007-01-01
Construction aggregates, primarily stone, sand and gravel, are recovered from widespread naturally occurring mineral deposits and processed for use primarily in the construction industry. They are mined, crushed, sorted by size and sold loose or combined with portland cement or asphaltic cement to make concrete products to build roads, houses, buildings, and other structures. Much smaller quantities are used in agriculture, cement manufacture, chemical and metallurgical processes, glass production and many other products.
Enabling personal genomics with an explicit test of epistasis.
Greene, Casey S; Himmelstein, Daniel S; Nelson, Heather H; Kelsey, Karl T; Williams, Scott M; Andrew, Angeline S; Karagas, Margaret R; Moore, Jason H
2010-01-01
One goal of personal genomics is to use information about genomic variation to predict who is at risk for various common diseases. Technological advances in genotyping have spawned several personal genetic testing services that market genotyping services directly to the consumer. An important goal of consumer genetic testing is to provide health information along with the genotyping results. This has the potential to integrate detailed personal genetic and genomic information into healthcare decision making. Despite the potential importance of these advances, there are some important limitations. One concern is that much of the literature that is used to formulate personal genetics reports is based on genetic association studies that consider each genetic variant independently of the others. It is our working hypothesis that the true value of personal genomics will only be realized when the complexity of the genotype-to-phenotype mapping relationship is embraced, rather than ignored. We focus here on complexity in genetic architecture due to epistasis or nonlinear gene-gene interaction. We have previously developed a multifactor dimensionality reduction (MDR) algorithm and software package for detecting nonlinear interactions in genetic association studies. In most prior MDR analyses, the permutation testing strategy used to assess statistical significance was unable to differentiate MDR models that captured only interaction effects from those that also detected independent main effects. Statistical interpretation of MDR models required post-hoc analysis using entropy-based measures of interaction information. We introduce here a novel permutation test that allows the effects of nonlinear interactions between multiple genetic variants to be specifically tested in a manner that is not confounded by linear additive effects. We show using simulated nonlinear interactions that the power using the explicit test of epistasis is no different than a standard permutation
Flexible magnetic planning boards are easily transported
NASA Technical Reports Server (NTRS)
1965-01-01
Easily transportable preprinted magnetic planning boards are made by coating thin sheet steel with clear plastic. Flexible magnetic boards used with paper charts are constructed from close mesh steel screen.
Explicit Formulae for the Continued Fraction Convergents of "Square Root of D"
ERIC Educational Resources Information Center
Braza, Peter A.
2010-01-01
The formulae for the convergents of continued fractions are always given recursively rather than in explicit form. This article derives explicit formulae for the convergents of the continued fraction expansions for square roots.
Quark matter under strong magnetic fields in chiral models
Rabhi, Aziz; Providencia, Constanca
2011-05-15
The chiral model is used to describe quark matter under strong magnetic fields and is compared to other models, the MIT bag model and the two-flavor Nambu-Jona-Lasinio model. The effect of vacuum corrections due to the magnetic field is discussed. It is shown that if the magnetic-field vacuum corrections are not taken into account explicitly, the parameters of the models should be fitted to low-density meson properties in the presence of the magnetic field.
Theoretical design of molecular nanomagnets for magnetic refrigeration
NASA Astrophysics Data System (ADS)
Garlatti, E.; Carretta, S.; Schnack, J.; Amoretti, G.; Santini, P.
2013-11-01
Molecular nanomagnets are promising materials for very-low-temperature magnetic refrigeration due to their enhanced magnetocaloric effect. By explicitly considering Carnot refrigeration cycles, we theoretically show that the best molecules for magnetic refrigeration between T ≃10 K and the sub-Kelvin region are those made of strongly ferromagnetically coupled magnetic ions, contrarily to the established belief. This recipe will provide a strong stimulus for designing new magnetic molecules for cryogenic technologies.
Inverse magnetic catalysis and confinement within a contact interaction model for quarks
NASA Astrophysics Data System (ADS)
Ahmad, A.; Raya, A.
2016-06-01
We evaluate the impact of an external magnetic field on the chiral symmetry and confinement-deconfinement transition temperatures by using a vector-vector contact interaction model for quarks regularized so as to include an explicit confining scale in the corresponding gap equation. Exploring the evolution of the chiral condensate and the confining scale with temperature T and magnetic field strength eB (e represents the fundamental electric charge), we determine the pseudo-critical temperatures for the chiral ({T}cχ ) and deconfinement (T c c ) transitions from their inflection points, respectively. By construction, {T}cχ ={T}cc in the chiral limit. Within a mean-field approximation, we observe the magnetic catalysis phenomenon, characterized by a rising behavior of {T}cχ and T c c with growing eB. By considering a lattice-inspired running coupling which monotonically decreases with eB, inverse magnetic catalysis takes place in our model. We explore the role of the magnetic field in the traits of the confinement-deconfinement transition described by the model. Our findings are also in agreement with predictions derived from effective models of strong interactions.
Integrable Magnetic Geodesic Flows on 2-Torus: New Examples via Quasi-Linear System of PDEs
NASA Astrophysics Data System (ADS)
Agapov, S. V.; Bialy, M.; Mironov, A. E.
2017-01-01
For a magnetic geodesic flow on the 2-torus the only known integrable example is that of a flow integrable for all energy levels. It has an integral linear in momenta and corresponds to a one parameter group preserving the Lagrangian function of the magnetic flow. In this paper the problem of integrability on a single energy level is considered. Then, in addition to the example mentioned above, a few other explicit examples with quadratic in momenta integrals can be constructed by means of the Maupertuis' principle. Recently we proved that such an integrability problem can be reduced to a remarkable semi-Hamiltonian system of quasi-linear PDEs and to the question of the existence of smooth periodic solutions for this system. Our main result of the present paper states that any Liouville metric with the zero magnetic field on the 2-torus can be analytically deformed to a Riemannian metric with a small magnetic field so that the magnetic geodesic flow on an energy level is integrable by means of an integral quadratic in momenta.
Explicit 3D continuum fracture modeling with smooth particle hydrodynamics
NASA Technical Reports Server (NTRS)
Benz, W.; Asphaug, E.
1993-01-01
Impact phenomena shaped our solar system. As usual for most solar system processes, the scales are far different than we can address directly in the laboratory. Impact velocities are often much higher than we can achieve, sizes are often vastly larger, and most impacts take place in an environment where the only gravitational force is the mutual pull of the impactors. The Smooth Particle Hydrodynamics (SPH) technique has been applied in the past to the simulations of giant impacts. In these simulations, the colliding objects were so massive (at least a sizeable fraction of the Earth's mass) that material strength was negligible compared to gravity. This assumption can no longer be made when the bodies are much smaller. To this end, we have developed a 3D SPH code that includes a strength model to which we have added a von Mises yielding relation for stresses beyond the Hugoniot Elastic Limit. At the lower stresses associated with brittle failure, we use a rate-dependent strength based on the nucleation of incipient flaws whose number density is given by a Weibull distribution. Following Grady and Kipp and Melosh et al., we introduce a state variable D ('damage'), 0 less than D less than 1, which expresses the local reduction in strength due to crack growth under tensile loading. Unfortunately for the hydrodynamics, Grady and Kipp's model predicts which fragments are the most probable ones and not the ones that are really formed. This means, for example, that if a given laboratory experiment is modeled, the fragment distribution obtained from the Grady-Kipp theory would be equivalent to a ensemble average over many realizations of the experiment. On the other hand, the hydrodynamics itself is explicit and evolves not an ensemble average but very specific fragments. Hence, there is a clear incompatibility with the deterministic nature of the hydrodynamics equations and the statistical approach of the Grady-Kipp dynamical fracture model. We remedy these shortcomings
Mross, David F; Alicea, Jason; Motrunich, Olexei I
2016-07-01
We explicitly derive the duality between a free electronic Dirac cone and quantum electrodynamics in (2+1) dimensions (QED_{3}) with N=1 fermion flavors. The duality proceeds via an exact, nonlocal mapping from electrons to dual fermions with long-range interactions encoded by an emergent gauge field. This mapping allows us to construct parent Hamiltonians for exotic topological-insulator surface phases, derive the particle-hole-symmetric field theory of a half-filled Landau level, and nontrivially constrain QED_{3} scaling dimensions. We similarly establish duality between bosonic topological insulator surfaces and N=2 QED_{3}.
Wang, Jihua; Zhang, Zhiyong; Liu, Haiyan; Shi, Yunyu
2003-06-01
The 124 independent molecular dynamics simulations are completed with total time of 196.8 ns. The calculated unfolding quasiequilibrium thermodynamics of G-IgG-binding domain B1 (GB1) shows the experimentally observed protein transitions: a coil to disordered globule transition, a disordered globule to molten globule transition, a molten globule to nativelike transition, and a nativelike to solidlike state transition. The first protein unfolding phase diagram has been constructed from molecular dynamics simulations with an explicit water model. The calculated melting temperature of GB1 agrees with early experiment. The results also agree with the recent experiment result in which GB1 has more than one intermediate.
C*-algebraic scattering theory and explicitly solvable quantum field theories
NASA Astrophysics Data System (ADS)
Warchall, Henry A.
1985-06-01
A general theoretical framework is developed for the treatment of a class of quantum field theories that are explicitly exactly solvable, but require the use of C*-algebraic techniques because time-dependent scattering theory cannot be constructed in any one natural representation of the observable algebra. The purpose is to exhibit mechanisms by which inequivalent representations of the observable algebra can arise in quantum field theory, in a setting free of other complications commonly associated with the specification of dynamics. One of two major results is the development of necessary and sufficient conditions for the concurrent unitary implementation of two automorphism groups in a class of quasifree representations of the algebra of the canonical commutation relations (CCR). The automorphism groups considered are induced by one-parameter groups of symplectic transformations on the classical phase space over which the Weyl algebra of the CCR is built; each symplectic group is conjugate by a fixed symplectic transformation to a one-parameter unitary group. The second result, an analog to the Birman-Belopol'skii theorem in two-Hilbert-space scattering theory, gives sufficient conditions for the existence of Mo/ller wave morphisms in theories with time-development automorphism groups of the above type. In a paper which follows, this framework is used to analyze a particular model system for which wave operators fail to exist in any natural representation of the observable algebra, but for which wave morphisms and an associated S matrix are easily constructed.
Explicit Symplectic-like Integrators with Midpoint Permutations for Spinning Compact Binaries
NASA Astrophysics Data System (ADS)
Luo, Junjie; Wu, Xin; Huang, Guoqing; Liu, Fuyao
2017-01-01
We refine the recently developed fourth-order extended phase space explicit symplectic-like methods for inseparable Hamiltonians using Yoshida’s triple product combined with a midpoint permuted map. The midpoint between the original variables and their corresponding extended variables at every integration step is readjusted as the initial values of the original variables and their corresponding extended ones at the next step integration. The triple-product construction is apparently superior to the composition of two triple products in computational efficiency. Above all, the new midpoint permutations are more effective in restraining the equality of the original variables and their corresponding extended ones at each integration step than the existing sequent permutations of momenta and coordinates. As a result, our new construction shares the benefit of implicit symplectic integrators in the conservation of the second post-Newtonian Hamiltonian of spinning compact binaries. Especially for the chaotic case, it can work well, but the existing sequent permuted algorithm cannot. When dissipative effects from the gravitational radiation reaction are included, the new symplectic-like method has a secular drift in the energy error of the dissipative system for the orbits that are regular in the absence of radiation, as an implicit symplectic integrator does. In spite of this, it is superior to the same-order implicit symplectic integrator in accuracy and efficiency. The new method is particularly useful in discussing the long-term evolution of inseparable Hamiltonian problems.
Explicitness in Science Discourse: A Gricean Account of Income-Related Differences
ERIC Educational Resources Information Center
Avenia-Tapper, Brianna; Isacoff, Nora M.
2016-01-01
Highly explicit language use is prized in scientific discourse, and greater explicitness is hypothesized to facilitate academic achievement. Studies in the mid-twentieth century reported controversial findings that the explicitness of text differs by the income and education levels of authors' families. If income-related differences in…
Product and Process Perspectives: an Empirical Study of Explicitation in Chinese-English Translation
ERIC Educational Resources Information Center
Fan, Zhewei
2012-01-01
Product-and process-oriented, this dissertation focuses on both the explicitness in translated texts and the implementation of explicitation in Chinese-English translation. In doing so, it provides a new cognitive framework for understanding explicitation as a strategic process. A specially designed study of the translation process facilitates the…
Stieger, Stefan; Kandler, Christian; Tran, Ulrich S; Pietschnig, Jakob; Voracek, Martin
2017-03-01
In today's world, researchers frequently utilize indirect measures of implicit (i.e., automatic, spontaneous) evaluations. The results of several studies have supported the usefulness of these measures in predicting behavior, as compared to utilizing direct measures of explicit (i.e., purposeful, deliberate) evaluations. A current, under-debate issue concerns the origin of these implicit evaluations. The present genetically sensitive multi-group study analyzed data from 223 twin pairs and 222 biological core families to estimate possible genetic and environmental sources of individual differences in implicit and explicit self-esteem and affect. The results show that implicit self-esteem and affect maintain a substantial genetic basis, but demonstrate little influence from the shared environment by siblings (e.g., shared familial socialization in childhood). A bivariate analysis found that implicit and explicit evaluations of the same construct share a common genetic core which aligns with the motivation and opportunity as determinants (MODE) model.
Multiresolution and Explicit Methods for Vector Field Analysis and Visualization
NASA Technical Reports Server (NTRS)
Nielson, Gregory M.
1997-01-01
This is a request for a second renewal (3d year of funding) of a research project on the topic of multiresolution and explicit methods for vector field analysis and visualization. In this report, we describe the progress made on this research project during the second year and give a statement of the planned research for the third year. There are two aspects to this research project. The first is concerned with the development of techniques for computing tangent curves for use in visualizing flow fields. The second aspect of the research project is concerned with the development of multiresolution methods for curvilinear grids and their use as tools for visualization, analysis and archiving of flow data. We report on our work on the development of numerical methods for tangent curve computation first.
Explicit guidance of drag modulated aeroassisted transfer between elliptical orbits
NASA Technical Reports Server (NTRS)
Vinh, N. X.; Mease, K. D.; Hanson, J. M.; Johannesen, J. R.
1984-01-01
This paper presents the complete analysis of the problem of minimum-fuel aeroassisted transfer between coplanar elliptical orbits in the case where the orientation of the final orbit is free for selection in the optimization process. The comparison between the optimal pure propulsive transfer and the idealized aeroassisted transfer, by several passages through the atmosphere, is made. In the case where aeroassisted transfer provides fuel saving, a practical scheme for its realization by one passage is proposed. The maneuver consists of three phases: a deorbit phase for nonzero entry angle, followed by an atmospheric fly-through with variable drag control and completed by a postatmospheric phase. An explicit guidance formula for drag control is derived and it is shown that the required exit speed for ascent to the final orbit can be obtained with a very high degree of accuracy.
Explicit solvent models in protein pKa calculations.
Gibas, C J; Subramaniam, S
1996-07-01
Continuum methods for calculation of protein electrostatics treat buried and ordered water molecules by one of two approximations; either the dielectric constant of regions containing ordered water molecules is equal to the bulk solvent dielectric constant, or it is equal to the protein dielectric constant though no fixed atoms are used to represent water molecules. A method for calculating the titration behavior of individual residues in proteins has been tested on models of hen egg white lysozyme containing various numbers of explicit water molecules. Water molecules were included based on hydrogen bonding, solvent accessibility, and/or proximity to titrating groups in the protein. Inclusion of water molecules significantly alters the calculated titration behavior of individual titrating sites, shifting calculated pKa values by up to 0.5 pH unit. Our results suggest that approximately one water molecule within hydrogen-bonding distance of each charged group should be included in protein electrostatics calculations.
Effects of explicit atmospheric convection at high CO2
Arnold, Nathan P.; Branson, Mark; Burt, Melissa A.; Abbot, Dorian S.; Kuang, Zhiming; Randall, David A.; Tziperman, Eli
2014-01-01
The effect of clouds on climate remains the largest uncertainty in climate change predictions, due to the inability of global climate models (GCMs) to resolve essential small-scale cloud and convection processes. We compare preindustrial and quadrupled CO2 simulations between a conventional GCM in which convection is parameterized and a “superparameterized” model in which convection is explicitly simulated with a cloud-permitting model in each grid cell. We find that the global responses of the two models to increased CO2 are broadly similar: both simulate ice-free Arctic summers, wintertime Arctic convection, and enhanced Madden–Julian oscillation (MJO) activity. Superparameterization produces significant differences at both CO2 levels, including greater Arctic cloud cover, further reduced sea ice area at high CO2, and a stronger increase with CO2 of the MJO. PMID:25024204
Explicit integration with GPU acceleration for large kinetic networks
Brock, Benjamin; Belt, Andrew; Billings, Jay Jay; ...
2015-09-15
In this study, we demonstrate the first implementation of recently-developed fast explicit kinetic integration algorithms on modern graphics processing unit (GPU) accelerators. Taking as a generic test case a Type Ia supernova explosion with an extremely stiff thermonuclear network having 150 isotopic species and 1604 reactions coupled to hydrodynamics using operator splitting, we demonstrate the capability to solve of order 100 realistic kinetic networks in parallel in the same time that standard implicit methods can solve a single such network on a CPU. In addition, this orders-of-magnitude decrease in computation time for solving systems of realistic kinetic networks implies thatmore » important coupled, multiphysics problems in various scientific and technical fields that were intractable, or could be simulated only with highly schematic kinetic networks, are now computationally feasible.« less
Explicit integration with GPU acceleration for large kinetic networks
Brock, Benjamin; Belt, Andrew; Billings, Jay Jay; Guidry, Mike W.
2015-09-15
In this study, we demonstrate the first implementation of recently-developed fast explicit kinetic integration algorithms on modern graphics processing unit (GPU) accelerators. Taking as a generic test case a Type Ia supernova explosion with an extremely stiff thermonuclear network having 150 isotopic species and 1604 reactions coupled to hydrodynamics using operator splitting, we demonstrate the capability to solve of order 100 realistic kinetic networks in parallel in the same time that standard implicit methods can solve a single such network on a CPU. In addition, this orders-of-magnitude decrease in computation time for solving systems of realistic kinetic networks implies that important coupled, multiphysics problems in various scientific and technical fields that were intractable, or could be simulated only with highly schematic kinetic networks, are now computationally feasible.
An explicit example of Hopf bifurcation in fluid mechanics
NASA Technical Reports Server (NTRS)
Kloeden, P.; Wells, R.
1983-01-01
It is observed that a complete and explicit example of Hopf bifurcation appears not to be known in fluid mechanics. Such an example is presented for the rotating Benard problem with free boundary conditions on the upper and lower faces, and horizontally periodic solutions. Normal modes are found for the linearization, and the Veronis computation of the wave numbers is modified to take into account the imposed horizontal periodicity. An invariant subspace of the phase space is found in which the hypotheses of the Joseph-Sattinger theorem are verified, thus demonstrating the Hopf bifurcation. The criticality calculations are carried through to demonstrate rigorously, that the bifurcation is subcritical for certain cases, and to demonstrate numerically that it is subcritical for all the cases in the paper.
Explicit integration with GPU acceleration for large kinetic networks
Brock, Benjamin; Belt, Andrew; Billings, Jay Jay; Guidry, Mike
2015-12-01
We demonstrate the first implementation of recently-developed fast explicit kinetic integration algorithms on modern graphics processing unit (GPU) accelerators. Taking as a generic test case a Type Ia supernova explosion with an extremely stiff thermonuclear network having 150 isotopic species and 1604 reactions coupled to hydrodynamics using operator splitting, we demonstrate the capability to solve of order 100 realistic kinetic networks in parallel in the same time that standard implicit methods can solve a single such network on a CPU. This orders-of-magnitude decrease in computation time for solving systems of realistic kinetic networks implies that important coupled, multiphysics problems in various scientific and technical fields that were intractable, or could be simulated only with highly schematic kinetic networks, are now computationally feasible.
Explicit Associative Learning and Memory in Synesthetes and Nonsynesthetes
Aslin, Richard N.
2016-01-01
Most current theories regarding the development of synesthesia focus on cross-modal neural connections and genetic underpinnings, but recent evidence has revitalized the potential role of associative learning. In the present study, we compared synesthetes’ and controls’ ability to explicitly learn shape-color pairings. Using a continuous measure of accuracy and multiple testing blocks, we found that synesthetes learned these pairings faster than controls. In a delayed retest, synesthetes outperformed controls, demonstrating enhanced long-term memory for shape–color associations. Following this retest, participants learned shuffled associations, and we found little evidence for group differences in subsequent learning ability. Overall, our findings support the hypothesis that synesthetes have exceptional associative learning abilities and further specify that this advantage pertains to the initial learning rate and long-term retention of associations. PMID:27698986
Anterior cingulate activity and level of cognitive conflict: explicit comparisons.
Mitchell, Rachel L C
2006-12-01
The role of anterior cingulate cortex (ACC) in attention is a matter of debate. One hypothesis suggests that its role is to monitor response-level conflict, but explicit evidence is somewhat lacking. In this study, the activation of ACC was compared in (a) color and number standard Stroop tasks in which response preparation and interference shared modality (response-level conflict) and (b) color and number matching Stroop tasks in which response preparation and interference did not share modality (non-response-level conflict). In the congruent conditions, there was no effect of task type. In the interference conditions, anterior cingulate activity in the matching tasks was less than that in the standard tasks. These results support the hypothesis that ACC specifically mediates generalized modality-independent selection processes invoked by response competition.
Explicit densities of multidimensional ballistic Lévy walks
NASA Astrophysics Data System (ADS)
Magdziarz, Marcin; Zorawik, Tomasz
2016-08-01
Lévy walks have proved to be useful models of stochastic dynamics with a number of applications in the modeling of real-life phenomena. In this paper we derive explicit formulas for densities of the two- (2D) and three-dimensional (3D) ballistic Lévy walks, which are most important in applications. It turns out that in the 3D case the densities are given by elementary functions. The densities of the 2D Lévy walks are expressed in terms of hypergeometric functions and the right-side Riemann-Liouville fractional derivative, which allows us to efficiently evaluate them numerically. The theoretical results agree perfectly with Monte Carlo simulations.
Phase behavior of a lattice hydrophobic oligomer in explicit water.
Romero-Vargas Castrillón, Santiago; Matysiak, Silvina; Stillinger, Frank H; Rossky, Peter J; Debenedetti, Pablo G
2012-08-09
We investigate the thermodynamics of hydrophobic oligomer collapse using a water-explicit, three-dimensional lattice model. The model captures several aspects of protein thermodynamics, including the emergence of cold- and thermal-unfolding, as well as unfolding at high solvent density (a phenomenon akin to pressure-induced denaturation). We show that over a range of conditions spanning a ≈14% increase in solvent density, the oligomer transforms into a compact, strongly water-penetrated conformation at low temperature. This contrasts with thermal unfolding at high temperature, where the system "denatures" into an extended random coil conformation. We report a phase diagram for hydrophobic collapse that correctly captures qualitative aspects of cold and thermal unfolding at low to intermediate solvent densities.
Explicit electromagnetic algorithm for 2D using a multi-fluid model in laser-produced plasmas
NASA Astrophysics Data System (ADS)
García, S.; Fuentes, F.; Paz, C.
2000-05-01
A new algorithm is presented for the explicit calculation of the electromagnetic fields in 2D simulation plasmas. This paper describes a multi-fluid model for the simulation of laser plasma interaction. Our description includes a simple two-electron fluid model and the background ions in a laser target, as coupled fluid components moving relative to a fixed Eulerian mesh. The electrons become a perfect gas obeying the non relativistic Maxwell-Boltzmann distribution. Braginskii's expression is used. The magnetic field equation is integrated in time by the Lax-Wendroff modified scheme, a method that is known to be stable as long as the Courant-Friedrichs-Lewy condition is satisfied. The first approximation step B m+1/2=+(
Multiresolution and Explicit Methods for Vector Field Analysis and Visualization
NASA Technical Reports Server (NTRS)
1996-01-01
We first report on our current progress in the area of explicit methods for tangent curve computation. The basic idea of this method is to decompose the domain into a collection of triangles (or tetrahedra) and assume linear variation of the vector field over each cell. With this assumption, the equations which define a tangent curve become a system of linear, constant coefficient ODE's which can be solved explicitly. There are five different representation of the solution depending on the eigenvalues of the Jacobian. The analysis of these five cases is somewhat similar to the phase plane analysis often associate with critical point classification within the context of topological methods, but it is not exactly the same. There are some critical differences. Moving from one cell to the next as a tangent curve is tracked, requires the computation of the exit point which is an intersection of the solution of the constant coefficient ODE and the edge of a triangle. There are two possible approaches to this root computation problem. We can express the tangent curve into parametric form and substitute into an implicit form for the edge or we can express the edge in parametric form and substitute in an implicit form of the tangent curve. Normally the solution of a system of ODE's is given in parametric form and so the first approach is the most accessible and straightforward. The second approach requires the 'implicitization' of these parametric curves. The implicitization of parametric curves can often be rather difficult, but in this case we have been successful and have been able to develop algorithms and subsequent computer programs for both approaches. We will give these details along with some comparisons in a forthcoming research paper on this topic.
Spatially explicit shallow landslide susceptibility mapping over large areas
Bellugi, Dino; Dietrich, William E.; Stock, Jonathan D.; McKean, Jim; Kazian, Brian; Hargrove, Paul
2011-01-01
Recent advances in downscaling climate model precipitation predictions now yield spatially explicit patterns of rainfall that could be used to estimate shallow landslide susceptibility over large areas. In California, the United States Geological Survey is exploring community emergency response to the possible effects of a very large simulated storm event and to do so it has generated downscaled precipitation maps for the storm. To predict the corresponding pattern of shallow landslide susceptibility across the state, we have used the model Shalstab (a coupled steady state runoff and infinite slope stability model) which susceptibility spatially explicit estimates of relative potential instability. Such slope stability models that include the effects of subsurface runoff on potentially destabilizing pore pressure evolution require water routing and hence the definition of upslope drainage area to each potential cell. To calculate drainage area efficiently over a large area we developed a parallel framework to scale-up Shalstab and specifically introduce a new efficient parallel drainage area algorithm which produces seamless results. The single seamless shallow landslide susceptibility map for all of California was accomplished in a short run time, and indicates that much larger areas can be efficiently modelled. As landslide maps generally over predict the extent of instability for any given storm. Local empirical data on the fraction of predicted unstable cells that failed for observed rainfall intensity can be used to specify the likely extent of hazard for a given storm. This suggests that campaigns to collect local precipitation data and detailed shallow landslide location maps after major storms could be used to calibrate models and improve their use in hazard assessment for individual storms.
Spatially explicit spectral analysis of point clouds and geospatial data
Buscombe, Daniel D.
2015-01-01
The increasing use of spatially explicit analyses of high-resolution spatially distributed data (imagery and point clouds) for the purposes of characterising spatial heterogeneity in geophysical phenomena necessitates the development of custom analytical and computational tools. In recent years, such analyses have become the basis of, for example, automated texture characterisation and segmentation, roughness and grain size calculation, and feature detection and classification, from a variety of data types. In this work, much use has been made of statistical descriptors of localised spatial variations in amplitude variance (roughness), however the horizontal scale (wavelength) and spacing of roughness elements is rarely considered. This is despite the fact that the ratio of characteristic vertical to horizontal scales is not constant and can yield important information about physical scaling relationships. Spectral analysis is a hitherto under-utilised but powerful means to acquire statistical information about relevant amplitude and wavelength scales, simultaneously and with computational efficiency. Further, quantifying spatially distributed data in the frequency domain lends itself to the development of stochastic models for probing the underlying mechanisms which govern the spatial distribution of geological and geophysical phenomena. The software packagePySESA (Python program for Spatially Explicit Spectral Analysis) has been developed for generic analyses of spatially distributed data in both the spatial and frequency domains. Developed predominantly in Python, it accesses libraries written in Cython and C++ for efficiency. It is open source and modular, therefore readily incorporated into, and combined with, other data analysis tools and frameworks with particular utility for supporting research in the fields of geomorphology, geophysics, hydrography, photogrammetry and remote sensing. The analytical and computational structure of the toolbox is
Explicit schemes for time propagating many-body wave functions
NASA Astrophysics Data System (ADS)
Frapiccini, Ana Laura; Hamido, Aliou; Schröter, Sebastian; Pyke, Dean; Mota-Furtado, Francisca; O'Mahony, Patrick F.; Madroñero, Javier; Eiglsperger, Johannes; Piraux, Bernard
2014-02-01
Accurate theoretical data on many time-dependent processes in atomic and molecular physics and in chemistry require the direct numerical ab initio solution of the time-dependent Schrödinger equation, thereby motivating the development of very efficient time propagators. These usually involve the solution of very large systems of first-order differential equations that are characterized by a high degree of stiffness. In this contribution, we analyze and compare the performance of the explicit one-step algorithms of Fatunla and Arnoldi. Both algorithms have exactly the same stability function, therefore sharing the same stability properties that turn out to be optimum. Their respective accuracy, however, differs significantly and depends on the physical situation involved. In order to test this accuracy, we use a predictor-corrector scheme in which the predictor is either Fatunla's or Arnoldi's algorithm and the corrector, a fully implicit four-stage Radau IIA method of order 7. In this contribution, we consider two physical processes. The first one is the ionization of an atomic system by a short and intense electromagnetic pulse; the atomic systems include a one-dimensional Gaussian model potential as well as atomic hydrogen and helium, both in full dimensionality. The second process is the decoherence of two-electron quantum states when a time-independent perturbation is applied to a planar two-electron quantum dot where both electrons are confined in an anharmonic potential. Even though the Hamiltonian of this system is time independent the corresponding differential equation shows a striking stiffness which makes the time integration extremely difficult. In the case of the one-dimensional Gaussian potential we discuss in detail the possibility of monitoring the time step for both explicit algorithms. In the other physical situations that are much more demanding in term of computations, we show that the accuracy of both algorithms depends strongly on the degree
Explicit shape descriptors: Novel morphologic features for histopathology classification
Sparks, Rachel; Madabhushi, Anant
2013-01-01
Object morphology, defined as shape and size characteristics, observed on medical imagery is often an important marker for disease presence and/or aggressiveness. In the context of prostate cancer histopathology, gland morphology is an integral component of the Gleason grading system which enables discrimination between low and high grade disease. However, clinicians are often unable to distinguish between subtle differences in object morphology, as evidenced by high inter-observer variability in Gleason grading. Boundary-based morphologic descriptors, such as the variance in the distance from points on the boundary of an object to its center, may not have the requisite discriminability to separate objects with subtle shape differences. In this paper, we present a set of novel explicit shape descriptors (ESDs) which are capable of distinguishing subtle shape differences between prostate glands of intermediate Gleason grades (grades 3 and 4) on prostate cancer histopathology. Calculation of ESDs involves: (1) representing object morphology using an explicit shape model (e.g. medial axis); (2) aligning the shape models via a non-rigid registration scheme with a diffeomorphic constraint and quantifying shape model dissimilarity; and (3) applying a non-linear dimensionality reduction scheme (e.g. Graph Embedding) to learn a low dimensional projection encoding the shape differences between objects. ESDs are hence the principal eigenvectors in the reduced embedding space. In this work we demonstrate that ESDs in conjunction with a Support Vector Machine classifier are able to correctly distinguish between 888 prostate glands corresponding to different Gleason grades (benign, grade 3, or grade 4) of prostate cancer from 58 needle biopsy specimens with a maximum accuracy of 0.89 and corresponding area under the receiver operating characteristic curve of 0.78. PMID:23850744
Spatially explicit spectral analysis of point clouds and geospatial data
NASA Astrophysics Data System (ADS)
Buscombe, Daniel
2016-01-01
The increasing use of spatially explicit analyses of high-resolution spatially distributed data (imagery and point clouds) for the purposes of characterising spatial heterogeneity in geophysical phenomena necessitates the development of custom analytical and computational tools. In recent years, such analyses have become the basis of, for example, automated texture characterisation and segmentation, roughness and grain size calculation, and feature detection and classification, from a variety of data types. In this work, much use has been made of statistical descriptors of localised spatial variations in amplitude variance (roughness), however the horizontal scale (wavelength) and spacing of roughness elements is rarely considered. This is despite the fact that the ratio of characteristic vertical to horizontal scales is not constant and can yield important information about physical scaling relationships. Spectral analysis is a hitherto under-utilised but powerful means to acquire statistical information about relevant amplitude and wavelength scales, simultaneously and with computational efficiency. Further, quantifying spatially distributed data in the frequency domain lends itself to the development of stochastic models for probing the underlying mechanisms which govern the spatial distribution of geological and geophysical phenomena. The software package PySESA (Python program for Spatially Explicit Spectral Analysis) has been developed for generic analyses of spatially distributed data in both the spatial and frequency domains. Developed predominantly in Python, it accesses libraries written in Cython and C++ for efficiency. It is open source and modular, therefore readily incorporated into, and combined with, other data analysis tools and frameworks with particular utility for supporting research in the fields of geomorphology, geophysics, hydrography, photogrammetry and remote sensing. The analytical and computational structure of the toolbox is described
Ganusov, Vitaly V
2008-01-01
Estimation of division and death rates of lymphocytes in different conditions is vital for quantitative understanding of the immune system. Deuterium, in the form of deuterated glucose or heavy water, can be used to measure rates of proliferation and death of lymphocytes in vivo. Inferring these rates from labeling and delabeling curves has been subject to considerable debate with different groups suggesting different mathematical models for that purpose. We show that the three models that are most commonly used are in fact mathematically identical and differ only in their interpretation of the estimated parameters. By extending these previous models, we here propose a more mechanistic approach for the analysis of data from deuterium labeling experiments. We construct a model of 'kinetic heterogeneity' in which the total cell population consists of many sub-populations with different rates of cell turnover. In this model, for a given distribution of the rates of turnover, the predicted fraction of labeled DNA accumulated and lost can be calculated. Our model reproduces several previously made experimental observations, such as a negative correlation between the length of the labeling period and the rate at which labeled DNA is lost after label cessation. We demonstrate the reliability of the new explicit kinetic heterogeneity model by applying it to artificially generated datasets, and illustrate its usefulness by fitting experimental data. In contrast to previous models, the explicit kinetic heterogeneity model (1) provides a mechanistic way of interpreting labeling data; (2) allows for a non-exponential loss of labeled cells during delabeling, and (3) can be used to describe data with variable labeling length.
2015-08-01
Germany. von Stackelberg, K., 2010. Spatially-Explicit Bioaccumulation Modeling. Presented at the Society for Environmental Toxicology and Chemistry ...Explicit Bioaccumulation Modeling. Presented at the Society for Environmental Toxicology and Chemistry Annual Meeting, November 2010, Portland, OR... Environmental Response, Compensation, and Liability Act CERCLIS Comprehensive Environmental Response, Compensation, and Liability Information System
Lieb-Mattis ferrimagnetism in magnetic semiconductors
NASA Astrophysics Data System (ADS)
Kuzian, R. O.; Richter, J.; Kuz'min, M. D.; Hayn, R.
2016-06-01
We show the possibility of long-range ferrimagnetic ordering with a saturation magnetization of ˜1 μB per spin for arbitrarily low concentration of magnetic impurities in semiconductors, provided that the impurities form a superstructure satisfying the conditions of the Lieb-Mattis theorem. Explicit examples of such superstructures are given for the wurtzite lattice, and the temperature of ferrimagnetic transition is estimated from a high-temperature expansion. Exact diagonalization studies show that small fragments of the structure exhibit enhanced magnetic response and isotropic superparamagnetism at low temperatures. A quantum transition in a high magnetic field is considered and similar superstructures in cubic semiconductors are discussed as well.
Magnetic phase transition in coupled spin-lattice systems: A replica-exchange Wang-Landau study.
Perera, Dilina; Vogel, Thomas; Landau, David P
2016-10-01
Coupled, dynamical spin-lattice models provide a unique test ground for simulations investigating the finite-temperature magnetic properties of materials under the direct influence of the lattice vibrations. These models are constructed by combining a coordinate-dependent interatomic potential with a Heisenberg-like spin Hamiltonian, facilitating the treatment of both the atomic coordinates and the spins as explicit phase variables. Using a model parameterized for bcc iron, we study the magnetic phase transition in these complex systems via the recently introduced, massively parallel replica-exchange Wang-Landau Monte Carlo method. Comparison with the results obtained from rigid lattice (spin-only) simulations shows that the transition temperature as well as the amplitude of the peak in the specific heat curve is marginally affected by the lattice vibrations. Moreover, the results were found to be sensitive to the particular choice of interatomic potential.
Magnetic phase transition in coupled spin-lattice systems: A replica-exchange Wang-Landau study
NASA Astrophysics Data System (ADS)
Perera, Dilina; Vogel, Thomas; Landau, David P.
2016-10-01
Coupled, dynamical spin-lattice models provide a unique test ground for simulations investigating the finite-temperature magnetic properties of materials under the direct influence of the lattice vibrations. These models are constructed by combining a coordinate-dependent interatomic potential with a Heisenberg-like spin Hamiltonian, facilitating the treatment of both the atomic coordinates and the spins as explicit phase variables. Using a model parameterized for bcc iron, we study the magnetic phase transition in these complex systems via the recently introduced, massively parallel replica-exchange Wang-Landau Monte Carlo method. Comparison with the results obtained from rigid lattice (spin-only) simulations shows that the transition temperature as well as the amplitude of the peak in the specific heat curve is marginally affected by the lattice vibrations. Moreover, the results were found to be sensitive to the particular choice of interatomic potential.
ERIC Educational Resources Information Center
Lieberfeld, Lawrence
1982-01-01
Many crucial questions need to be answered before a college embarks on a construction project and makes a substantial financial commitment. Computer modeling techniques can be used to make even complex project feasibility analyses. Available from Peat, Marwick, Mitchell & Co., 345 Park Avenue, New York, NY 10154. (MSE)
NASA Astrophysics Data System (ADS)
Henderson, Austin
This chapter chronicles the growth of the author's understanding of Media Space through his 20-year experience with coupling spaces, using video. It is a “technology-first” understanding of the construction of space. Key ideas from research studies and practice are presented, and contrasts with other genres of communication are made. The implications for distributed collaboration are explored.
Radler, M.
1998-04-13
Tables list major construction projects for refineries, petrochemical plants, sulfur plants, natural gas processing plants, and gas and oil pipelines. Data are compiled by country, company name, project type, added capacity, status of the project, expected completion date, contractor and contract type. Gas processes include LPG recovery, cryogenic separation, turboexpanders, LNG, liquefaction, desulfurization, NGL recovery, dehydration, hydrogen plants, and fractionators.
ERIC Educational Resources Information Center
Pietropola, Anne
1998-01-01
Describes a lesson designed to culminate a year of eighth-grade art classes in which students explore elements of design and space by creating 3-D abstract constructions. Outlines the process of using foam board and markers to create various shapes and optical effects. (DSK)
Poopari, Mohammad Reza; Dezhahang, Zahra; Xu, Yunjie
2013-02-07
Vibrational absorption (VA) and vibrational circular dichroism (VCD) spectra of methyl mandelate, a prototype chiral molecule, in a series of organic solvents, namely methanol (MeOH-d(4)), dimethyl sulfoxide (DMSO-d(6)), and chloroform (CDCl(3)), have been measured in the finger print region from 1800 to 1150 cm(-1). Implicit solvation models in the form of polarizable continuum model and explicit solvation models have been employed independently and simultaneously. The goal is to evaluate their efficiencies in dealing with solvent effects in each solution and to establish a general strategy to adequately account for effects of solvents. Molecular dynamics (MD) simulation and radial distribution function analysis have been performed to aid the construction of the explicit solvation models. Initial geometry searches have been carried out at the B3LYP/6-31G(d) level for the methyl mandelate monomer and its explicit 1 : 1 and 1 : 2 solute-solvent hydrogen-bonded complexes. B3LYP/cc-pVTZ has been used for all the final geometry optimizations, the vibrational frequency, VA and VCD intensity, and optical rotation dispersion (ORD) calculations. The results show that inclusion of solvent explicitly and implicitly at the same time has significant impacts on the appearance of the VA and VCD spectra, and is crucial for reliable spectral assignments when solvents are capable of hydrogen-bonding interactions with solutes. When no strong solvent-solute hydrogen-bonding interactions in the case of chloroform are expected, the gas phase monomer model is adequate for spectral interpretation, while inclusion of implicit solvation improves the frequency agreement with experiment. ORD spectra of methyl mandelate in the aforementioned solvents at different concentrations under 5 excitation wavelengths have also been measured. The comparison between the calculated and the experimental ORD spectra supports the conclusions drawn from the VA and VCD investigations.
NASA Astrophysics Data System (ADS)
de Silva, Piotr; Corminboeuf, Clémence
2015-09-01
We construct an orbital-free non-empirical meta-generalized gradient approximation (GGA) functional, which depends explicitly on density through the density overlap regions indicator [P. de Silva and C. Corminboeuf, J. Chem. Theory Comput. 10, 3745 (2014)]. The functional does not depend on either the kinetic energy density or the density Laplacian; therefore, it opens a new class of meta-GGA functionals. By construction, our meta-GGA yields exact exchange and correlation energy for the hydrogen atom and recovers the second order gradient expansion for exchange in the slowly varying limit. We show that for molecular systems, overall performance is better than non-empirical GGAs. For atomization energies, performance is on par with revTPSS, without any dependence on Kohn-Sham orbitals.
Silva, Piotr de Corminboeuf, Clémence
2015-09-21
We construct an orbital-free non-empirical meta-generalized gradient approximation (GGA) functional, which depends explicitly on density through the density overlap regions indicator [P. de Silva and C. Corminboeuf, J. Chem. Theory Comput. 10, 3745 (2014)]. The functional does not depend on either the kinetic energy density or the density Laplacian; therefore, it opens a new class of meta-GGA functionals. By construction, our meta-GGA yields exact exchange and correlation energy for the hydrogen atom and recovers the second order gradient expansion for exchange in the slowly varying limit. We show that for molecular systems, overall performance is better than non-empirical GGAs. For atomization energies, performance is on par with revTPSS, without any dependence on Kohn-Sham orbitals.
Numerical homogenization of concrete microstructures without explicit meshes
Sanahuja, Julien Toulemonde, Charles
2011-12-15
Life management of electric hydro or nuclear power plants requires to estimate long-term concrete properties on facilities, for obvious safety and serviceability reasons. Decades-old structures are foreseen to be operational for several more decades. As a large number of different concrete formulations are found in EDF facilities, empirical models based on many experiments cannot be an option for a large fleet of power plant buildings. To build predictive models, homogenization techniques offer an appealing alternative. To properly upscale creep, especially at long term, a rather precise description of the microstructure is required. However, the complexity of the morphology of concrete poses several challenges. In particular, concrete is formulated to maximize the packing density of the granular skeleton, leading to aggregates spanning several length scales with small inter particle spacings. Thus, explicit meshing of realistic concrete microstructures is either out of reach of current meshing algorithms or would produce a number of degrees of freedom far higher than the current generic FEM codes capabilities. This paper proposes a method to deal with complex matrix-inclusions microstructures such as the ones encountered at the mortar or concrete scales, without explicitly meshing them. The microstructure is superimposed to an independent mesh, which is a regular Cartesian grid. This inevitably yields so called 'gray elements', spanning across multiple phases. As the reliability of the estimate of the effective properties highly depends on the behavior affected to these gray elements, special attention is paid to them. As far as the question of the solvers is concerned, generic FEM codes are found to lack efficiency: they cannot reach high enough levels of discretization with classical free meshes, and they do not take advantage of the regular structure of the mesh. Thus, a specific finite differences/finite volumes solver has been developed. At first, generic off
NASA Technical Reports Server (NTRS)
Groom, Nelson J.; Poole, William L.
1991-01-01
Microcomputer-controlled magnetic-bearing test fixture used to develop approaches to design of controls for magnetic bearing actuators designed and constructed. Includes load cells connected to bar, in turn, connected through screw positioners to geared drive motors. Position of equivalent suspended element sensed by position sensors and controlled by drive motors. Provides control of gap in magnetic bearing and of current in electromagnet coil. Measurements made include magnetic-bearing gaps, magnetic flux in bearing gaps, and bearing forces. Approaches to linearization and control developed by use of fixture applicable to wide range of small-gap suspension systems.
NASA Astrophysics Data System (ADS)
Marshall, A.
A form of composites known as structural sandwich construction is presented in terms of materials used, design details for solving edging and attachment problems, and charts of design material analysis. Sandwich construction is used in nearly all commercial airliners and helicopters, and military air and space vehicles, and it is shown that this method can stiffen a structure without causing a weight increase. The facing material can be made of 2024 or 7075 aluminum alloy, titanium, or stainless steel, and the core material can be wood or foam. The properties of paper honeycomb and various aluminum alloy honeycombs are presented. Factors pertaining to adhesive materials are discussed, including products given off during cure, bonding pressure, and adaptability. Design requirements and manufacturing specifications are resolved using numerous suggestions.
NASA Technical Reports Server (NTRS)
Roda, J.
1975-01-01
Forty-four years ago the first successful metal airship was completed and delivered to the United States Navy, the ZMC-2. Between those years and the present, very little effort or serious consideration has been given to the manufacture, design, construction, or economic impact of airships. It is important to retain and exploit the small but continually diminishing pool of airship talent that will expedite the success of the United States in what is now a pioneering venture. The relative simplicity of airship construction, utilizing the tremendous technical advances of the last 44 years, leads to the conclusion that this form of transportation holds great promise for reducing costs of military missions and improving the international competitive position of the United States in commercial applications.
Prat-Camps, Jordi; Navau, Carles; Sanchez, Alvaro
2015-08-20
Wormholes are fascinating cosmological objects that can connect two distant regions of the universe. Because of their intriguing nature, constructing a wormhole in a lab seems a formidable task. A theoretical proposal by Greenleaf et al. presented a strategy to build a wormhole for electromagnetic waves. Based on metamaterials, it could allow electromagnetic wave propagation between two points in space through an invisible tunnel. However, an actual realization has not been possible until now. Here we construct and experimentally demonstrate a magnetostatic wormhole. Using magnetic metamaterials and metasurfaces, our wormhole transfers the magnetic field from one point in space to another through a path that is magnetically undetectable. We experimentally show that the magnetic field from a source at one end of the wormhole appears at the other end as an isolated magnetic monopolar field, creating the illusion of a magnetic field propagating through a tunnel outside the 3D space. Practical applications of the results can be envisaged, including medical techniques based on magnetism.
Prat-Camps, Jordi; Navau, Carles; Sanchez, Alvaro
2015-01-01
Wormholes are fascinating cosmological objects that can connect two distant regions of the universe. Because of their intriguing nature, constructing a wormhole in a lab seems a formidable task. A theoretical proposal by Greenleaf et al. presented a strategy to build a wormhole for electromagnetic waves. Based on metamaterials, it could allow electromagnetic wave propagation between two points in space through an invisible tunnel. However, an actual realization has not been possible until now. Here we construct and experimentally demonstrate a magnetostatic wormhole. Using magnetic metamaterials and metasurfaces, our wormhole transfers the magnetic field from one point in space to another through a path that is magnetically undetectable. We experimentally show that the magnetic field from a source at one end of the wormhole appears at the other end as an isolated magnetic monopolar field, creating the illusion of a magnetic field propagating through a tunnel outside the 3D space. Practical applications of the results can be envisaged, including medical techniques based on magnetism. PMID:26292278
Barry, B.A.
1988-01-01
This text/reference on construction measurements contains material concerning electronic surveying and remote sensing. New to this edition is coverage of the GPS satellite positioning system, electronic distance measurement (EDM), laser sweep, calculator techniques, radial surveying and tracking, Loran-C, inertial navigation surveying, 3-point resection, computer software, and electronic fieldbooks. It covers the difference of elevation, angle measurements and directions, coordinate surveying and layout, offshore measurements, and random field and office techniques.
Magnetically leviated superconducting bearing
Weinberger, Bernard R.; Lynds, Jr., Lahmer
1993-01-01
A magnetically levitated superconducting bearing includes a magnet (2) mounted on a shaft (12) that is rotatable around an axis of rotation and a Type II superconductor (6) supported on a stator (14) in proximity to the magnet (2). The superconductor (6) is positioned so that when it is cooled to its superconducting state in the presence of a magnetic field, it interacts with the magnet (2) to produce an attractive force that levitates the magnet (2) and supports a load on the shaft (12). The interaction between the superconductor (6) and magnet(2) also produces surface screening currents (8) that generate a repulsive force perpendicular to the load. The bearing also has means for maintaining the superconductor at a temperature below its critical temperature (16, 18). The bearing could also be constructed so the magnet (2) is supported on the stator (14) and the superconductor (6) is mounted on the shaft (12). The bearing can be operated by cooling the superconductor (6) to its superconducting state in the presence of a magnetic field.
Explicit expressions of quantum mechanical rotation operators for spins 1 to 2
NASA Astrophysics Data System (ADS)
Kocakoç, Mehpeyker; Tapramaz, Recep
2016-03-01
Quantum mechanical rotation operators are the subject of quantum mechanics, mathematics and pulsed magnetic resonance spectroscopies, namely NMR, EPR and ENDOR. They are also necessary for spin based quantum information systems. The rotation operators of spin 1/2 are well known and can be found in related textbooks. But rotation operators of other spins greater than 1/2 can be found numerically by evaluating the series expansions of exponential operator obtained from Schrödinger equation, or by evaluating Wigner-d formula or by evaluating recently established expressions in polynomial forms discussed in the text. In this work, explicit symbolic expressions of x, y and z components of rotation operators for spins 1 to 2 are worked out by evaluating series expansion of exponential operator for each element of operators and utilizing linear curve fitting process. The procedures gave out exact expressions of each element of the rotation operators. The operators of spins greater than 2 are under study and will be published in a separate paper.
Discoveries in Superconductivity, Persistent-Switch Magnets, and Magnetic Cooling
NASA Astrophysics Data System (ADS)
Adams, E. Dwight
2016-11-01
A historical review of developments in superconducting magnets begins with Kamerlingh Onnes' construction of the first one in 1914 and extends to the invention of the superconducting persistent switch reported in 1963. A section on magnetic cooling includes refrigeration by paramagnetic salts and by nuclei in metals, as well as direct nuclear demagnetization in which only the nuclei are cooled.
Explicit inclusion of nonlocality in (d,p) transfer reactions
Titus, L. J.; Nunes, F. M.; Potel, G.
2016-01-06
Traditionally, nucleon-nucleus optical potentials are made local for convenience. In recent work we studied the effects of including nonlocal interactions explicitly in the final state for (d,p) reactions, within the distorted wave Born approximation. Our goal in this work is to develop an improved formalism for nonlocal interactions that includes deuteron breakup and to use it to study the effects of including nonlocal interactions in transfer (d,p) reactions, in both the deuteron and the proton channel. We extend the finite-range adiabatic distorted wave approximation to include nonlocal nucleon optical potentials. We apply our method to (d,p) reactions on 16O, 40Ca,more » 48Ca, 126Sn, 132Sn, and 208Pb at 10, 20 and 50 MeV. Here, we find that nonlocality in the deuteron scattering state reduces the amplitude of the wave function in the nuclear interior, and shifts the wave function outward. In many cases, this has the effect of increasing the transfer cross section at the first peak of the angular distributions. This increase was most significant for heavy targets and for reactions at high energies. Lastly, our systematic study shows that, if only local optical potentials are used in the analysis of experimental (d, p) transfer cross sections, the extracted spectroscopic factors may be incorrect by up to 40% due to the local approximation.« less
Explicit B-spline regularization in diffeomorphic image registration
Tustison, Nicholas J.; Avants, Brian B.
2013-01-01
Diffeomorphic mappings are central to image registration due largely to their topological properties and success in providing biologically plausible solutions to deformation and morphological estimation problems. Popular diffeomorphic image registration algorithms include those characterized by time-varying and constant velocity fields, and symmetrical considerations. Prior information in the form of regularization is used to enforce transform plausibility taking the form of physics-based constraints or through some approximation thereof, e.g., Gaussian smoothing of the vector fields [a la Thirion's Demons (Thirion, 1998)]. In the context of the original Demons' framework, the so-called directly manipulated free-form deformation (DMFFD) (Tustison et al., 2009) can be viewed as a smoothing alternative in which explicit regularization is achieved through fast B-spline approximation. This characterization can be used to provide B-spline “flavored” diffeomorphic image registration solutions with several advantages. Implementation is open source and available through the Insight Toolkit and our Advanced Normalization Tools (ANTs) repository. A thorough comparative evaluation with the well-known SyN algorithm (Avants et al., 2008), implemented within the same framework, and its B-spline analog is performed using open labeled brain data and open source evaluation tools. PMID:24409140
Spatially explicit assessment of estuarine fish after Deepwater ...
Evaluating long- term contaminant effects on wildlife populations depends on spatial information about habitat quality, heterogeneity in contaminant exposure, and sensitivities and distributions of species integrated into a systems modeling approach. Rarely is this information readily available, making it difﬁcult to determine the applicability of realistic models to quantify population- level risks. To evaluate the trade- offs between data demands and increased speciﬁcity of spatially explicit models for population- level risk assessments, we developed a model for a standard toxicity test species, the sheepshead minnow (Cyprinodon variegatus), exposed to oil contamination following the Deepwater Horizon oil spill and compared the output with various levels of model complexity to a standard risk quotient approach. The model uses habitat and ﬁsh occupancy data collected over ﬁve sampling periods throughout 2008–2010 in Pensacola and Choctawhatchee Bays, Florida, USA, to predict species distribution, ﬁeld- collected and publically available data on oil distribution and concentration, and chronic toxicity data from laboratory assays applied to a matrix population model. The habitat suitability model established distribution of ﬁsh within Barataria Bay, Louisiana, USA, and the population model projected the dynamics of the species in the study area over a 5- yr period (October 2009–September 2014). Vital rates were modiﬁed according to estimated co
Electrostatic interactions in charged nanoslits within an explicit solvent theory.
Buyukdagli, Sahin
2015-11-18
Within a dipolar Poisson-Boltzmann theory including electrostatic correlations, we consider the effect of explicit solvent structure on solvent and ion partition confined to charged nanopores. We develop a relaxation scheme for the solution of this highly non-linear integro-differential equation for the electrostatic potential. The scheme is an extension of the approach previously introduced for simple planes (Buyukdagli and Blossey 2014 J. Chem. Phys. 140 234903) to nanoslit geometry. We show that the reduced dielectric response of solvent molecules at the membrane walls gives rise to an electric field significantly stronger than the field of the classical Poisson-Boltzmann equation. This peculiarity associated with non-local electrostatic interactions results in turn in an interfacial counterion adsorption layer absent in continuum theories. The observation of this enhanced counterion affinity in the very close vicinity of the interface may have important impacts on nanofluidic transport through charged nanopores. Our results indicate the quantitative inaccuracy of solvent implicit nanofiltration theories in predicting the ionic selectivity of membrane nanopores.
Parametrizing linear generalized Langevin dynamics from explicit molecular dynamics simulations
NASA Astrophysics Data System (ADS)
Gottwald, Fabian; Karsten, Sven; Ivanov, Sergei D.; Kühn, Oliver
2015-06-01
Fundamental understanding of complex dynamics in many-particle systems on the atomistic level is of utmost importance. Often the systems of interest are of macroscopic size but can be partitioned into a few important degrees of freedom which are treated most accurately and others which constitute a thermal bath. Particular attention in this respect attracts the linear generalized Langevin equation, which can be rigorously derived by means of a linear projection technique. Within this framework, a complicated interaction with the bath can be reduced to a single memory kernel. This memory kernel in turn is parametrized for a particular system studied, usually by means of time-domain methods based on explicit molecular dynamics data. Here, we discuss that this task is more naturally achieved in frequency domain and develop a Fourier-based parametrization method that outperforms its time-domain analogues. Very surprisingly, the widely used rigid bond method turns out to be inappropriate in general. Importantly, we show that the rigid bond approach leads to a systematic overestimation of relaxation times, unless the system under study consists of a harmonic bath bi-linearly coupled to the relevant degrees of freedom.
Global spatially explicit CO2 emission metrics for forest bioenergy.
Cherubini, Francesco; Huijbregts, Mark; Kindermann, Georg; Van Zelm, Rosalie; Van Der Velde, Marijn; Stadler, Konstantin; Strømman, Anders Hammer
2016-02-02
Emission metrics aggregate climate impacts of greenhouse gases to common units such as CO2-equivalents (CO2-eq.). Examples include the global warming potential (GWP), the global temperature change potential (GTP) and the absolute sustained emission temperature (aSET). Despite the importance of biomass as a primary energy supplier in existing and future scenarios, emission metrics for CO2 from forest bioenergy are only available on a case-specific basis. Here, we produce global spatially explicit emission metrics for CO2 emissions from forest bioenergy and illustrate their applications to global emissions in 2015 and until 2100 under the RCP8.5 scenario. We obtain global average values of 0.49 ± 0.03 kgCO2-eq. kgCO2(-1) (mean ± standard deviation) for GWP, 0.05 ± 0.05 kgCO2-eq. kgCO2(-1) for GTP, and 2.14·10(-14) ± 0.11·10(-14) °C (kg yr(-1))(-1) for aSET. We explore metric dependencies on temperature, precipitation, biomass turnover times and extraction rates of forest residues. We find relatively high emission metrics with low precipitation, long rotation times and low residue extraction rates. Our results provide a basis for assessing CO2 emissions from forest bioenergy under different indicators and across various spatial and temporal scales.
Simulating Space Capsule Water Landing with Explicit Finite Element Method
NASA Technical Reports Server (NTRS)
Wang, John T.; Lyle, Karen H.
2007-01-01
A study of using an explicit nonlinear dynamic finite element code for simulating the water landing of a space capsule was performed. The finite element model contains Lagrangian shell elements for the space capsule and Eulerian solid elements for the water and air. An Arbitrary Lagrangian Eulerian (ALE) solver and a penalty coupling method were used for predicting the fluid and structure interaction forces. The space capsule was first assumed to be rigid, so the numerical results could be correlated with closed form solutions. The water and air meshes were continuously refined until the solution was converged. The converged maximum deceleration predicted is bounded by the classical von Karman and Wagner solutions and is considered to be an adequate solution. The refined water and air meshes were then used in the models for simulating the water landing of a capsule model that has a flexible bottom. For small pitch angle cases, the maximum deceleration from the flexible capsule model was found to be significantly greater than the maximum deceleration obtained from the corresponding rigid model. For large pitch angle cases, the difference between the maximum deceleration of the flexible model and that of its corresponding rigid model is smaller. Test data of Apollo space capsules with a flexible heat shield qualitatively support the findings presented in this paper.
Spatially-explicit models of global tree density
NASA Astrophysics Data System (ADS)
Glick, Henry B.; Bettigole, Charlie; Maynard, Daniel S.; Covey, Kristofer R.; Smith, Jeffrey R.; Crowther, Thomas W.
2016-08-01
Remote sensing and geographic analysis of woody vegetation provide means of evaluating the distribution of natural resources, patterns of biodiversity and ecosystem structure, and socio-economic drivers of resource utilization. While these methods bring geographic datasets with global coverage into our day-to-day analytic spheres, many of the studies that rely on these strategies do not capitalize on the extensive collection of existing field data. We present the methods and maps associated with the first spatially-explicit models of global tree density, which relied on over 420,000 forest inventory field plots from around the world. This research is the result of a collaborative effort engaging over 20 scientists and institutions, and capitalizes on an array of analytical strategies. Our spatial data products offer precise estimates of the number of trees at global and biome scales, but should not be used for local-level estimation. At larger scales, these datasets can contribute valuable insight into resource management, ecological modelling efforts, and the quantification of ecosystem services.
Enforcing realizability in explicit multi-component species transport
McDermott, Randall J.; Floyd, Jason E.
2015-01-01
We propose a strategy to guarantee realizability of species mass fractions in explicit time integration of the partial differential equations governing fire dynamics, which is a multi-component transport problem (realizability requires all mass fractions are greater than or equal to zero and that the sum equals unity). For a mixture of n species, the conventional strategy is to solve for n − 1 species mass fractions and to obtain the nth (or “background”) species mass fraction from one minus the sum of the others. The numerical difficulties inherent in the background species approach are discussed and the potential for realizability violations is illustrated. The new strategy solves all n species transport equations and obtains density from the sum of the species mass densities. To guarantee realizability the species mass densities must remain positive (semidefinite). A scalar boundedness correction is proposed that is based on a minimal diffusion operator. The overall scheme is implemented in a publicly available large-eddy simulation code called the Fire Dynamics Simulator. A set of test cases is presented to verify that the new strategy enforces realizability, does not generate spurious mass, and maintains second-order accuracy for transport. PMID:26692634
Active messages versus explicit message passing under SUNMOS
Riesen, R.; Wheat, S.R.; Maccabe, A.B.
1994-07-01
In the past few years much effort has been devoted to finding faster and more convenient ways to exchange data between nodes of massively parallel distributed memory machines. One such approach, taken by Thorsten von Eicken et al. is called Active Messages. The idea is to hide message passing latency and continue to compute while data is being sent and delivered. The authors have implemented Active Messages under SUNMOS for the Intel Paragon and performed various experiments to determine their efficiency and utility. In this paper they concentrate on the subset of the Active Message layer that is used by the implementation of the Split-C library. They compare performance to explicit message passing under SUNMOS and explore new ways to support Split-C without Active Messages. They also compare the implementation to the original one on the Thinking Machines CM-5 and try to determine what the effects of low latency and low band-width versus high latency and high bandwidth are on user codes.
Calibration of piezoelectric RL shunts with explicit residual mode correction
NASA Astrophysics Data System (ADS)
Høgsberg, Jan; Krenk, Steen
2017-01-01
Piezoelectric RL (resistive-inductive) shunts are passive resonant devices used for damping of dominant vibration modes of a flexible structure and their efficiency relies on the precise calibration of the shunt components. In the present paper improved calibration accuracy is attained by an extension of the local piezoelectric transducer displacement by two additional terms, representing the flexibility and inertia contributions from the residual vibration modes not directly addressed by the shunt damping. This results in an augmented dynamic model for the targeted resonant vibration mode, in which the residual contributions, represented by two correction factors, modify both the apparent transducer capacitance and the shunt circuit impedance. Explicit expressions for the correction of the shunt circuit inductance and resistance are presented in a form that is generally applicable to calibration formulae derived on the basis of an assumed single-mode structure, where modal interaction has been neglected. A design procedure is devised and subsequently verified by a numerical example, which demonstrates that effective mitigation can be obtained for an arbitrary vibration mode when the residual mode correction is included in the calibration of the RL shunt.
Explicitly Correlated Methods within the ccCA Methodology.
Mahler, Andrew; Wilson, Angela K
2013-03-12
The prediction of energetic properties within "chemical accuracy" (1 kcal mol(-1) from well-established experiment) can be a major challenge in computational quantum chemistry due to the computational requirements (computer time, memory, and disk space) needed to achieve this level of accuracy. Methodologies such as coupled cluster with single, double, and perturbative triple excitations (CCSD(T)) combined with very large basis sets are often required to reach this level of accuracy. Unfortunately, such calculations quickly become cost prohibitive as system size increases. Our group has developed an ab initio composite method, the correlation consistent Composite Approach (ccCA), which enables such accuracy to be possible, on average, but at reduced computational cost as compared with CCSD(T) in combination with a large basis set. While ccCA has proven quite useful, computational bottlenecks still occur. In this study, the means to reduce the computational cost of ccCA without compromising accuracy by utilizing explicitly correlated methods within ccCA have been considered, and an alternative formulation is described.
Maximum sustainable yields from a spatially-explicit harvest model.
Takashina, Nao; Mougi, Akihiko
2015-10-21
Spatial heterogeneity plays an important role in complex ecosystem dynamics, and therefore is also an important consideration in sustainable resource management. However, little is known about how spatial effects can influence management targets derived from a non-spatial harvest model. Here, we extended the Schaefer model, a conventional non-spatial harvest model that is widely used in resource management, to a spatially-explicit harvest model by integrating environmental heterogeneities, as well as species exchange between patches. By comparing the maximum sustainable yields (MSY), one of the central management targets in resource management, obtained from the spatially extended model with that of the conventional model, we examined the effect of spatial heterogeneity. When spatial heterogeneity exists, we found that the Schaefer model tends to overestimate the MSY, implying potential for causing overharvesting. In addition, by assuming a well-mixed population in the heterogeneous environment, we showed analytically that the Schaefer model always overestimate the MSY, regardless of the number of patches existing. The degree of overestimation becomes significant when spatial heterogeneity is marked. Collectively, these results highlight the importance of integrating the spatial structure to conduct sustainable resource management.
Explicit B-spline regularization in diffeomorphic image registration.
Tustison, Nicholas J; Avants, Brian B
2013-01-01
Diffeomorphic mappings are central to image registration due largely to their topological properties and success in providing biologically plausible solutions to deformation and morphological estimation problems. Popular diffeomorphic image registration algorithms include those characterized by time-varying and constant velocity fields, and symmetrical considerations. Prior information in the form of regularization is used to enforce transform plausibility taking the form of physics-based constraints or through some approximation thereof, e.g., Gaussian smoothing of the vector fields [a la Thirion's Demons (Thirion, 1998)]. In the context of the original Demons' framework, the so-called directly manipulated free-form deformation (DMFFD) (Tustison et al., 2009) can be viewed as a smoothing alternative in which explicit regularization is achieved through fast B-spline approximation. This characterization can be used to provide B-spline "flavored" diffeomorphic image registration solutions with several advantages. Implementation is open source and available through the Insight Toolkit and our Advanced Normalization Tools (ANTs) repository. A thorough comparative evaluation with the well-known SyN algorithm (Avants et al., 2008), implemented within the same framework, and its B-spline analog is performed using open labeled brain data and open source evaluation tools.
An explicit expression of supremum of bounded quantum observables
Xu Xiaoming; Du Hongke; Fang Xiaochun
2009-03-15
Bounded observables corresponding to a quantum system are usually represented by S(H), the set of all bounded linear self-adjoint operators on a Hilbert space H. In 2006, Gudder introduced a logic order, prcue, on S(H). For A,B(set-membership sign)S(H), A prcue B if and only if there exists C(set-membership sign)S(H) such that AC=0 and A+C=B. Given A,B(set-membership sign)S(H), let A or B be the least upper bound (supremum) for A and B with respect to the Gudder order. In 2007, Pulmannova and Vincenkova proved that A or B exists if and only if A and B have an upper bound for the Gudder order. In this paper, we present some new necessary and sufficient conditions for which A or B exists and give an explicit representation of A or B (if A or B exists).0.
Compensatory heterogeneity in spatially explicit capture-recapture data.
Efford, M G; Mowat, G
2014-05-01
Spatially explicit capture-recapture methods, used widely to estimate the abundance of large carnivores, allow for movement within home ranges during sampling. Probability of detection is a decreasing function of distance from the home range center, with one parameter for magnitude and another for spatial scale. Sex-based and other differences in home range size potentially cause heterogeneity in individual detection and bias in estimates of density. The two parameters of detection have hitherto been treated as independent, but we suggest that an inverse relation is expected when detection probability depends on time spent near the detector. Variation in the spatial scale of detection is then compensated by reciprocal variation in the magnitude parameter. We define a net measure of detection ("single-detector sampling area," a(0)), and show by simulation that its coefficient of variation (CV) is a better predictor of bias than the CV of either component or the sum of their squared CVs. In an example using the grizzly bear Ursus arctos, the estimated sex variation in a(0) was small despite large variation in each component. From the simulations, the relative bias of density estimates was generally negligible (< 5%) when CV(a(0)) < 30%. Parameterization of the detection model in terms of a(0) and spatial scale can be more parsimonious and significantly aids the biological interpretation of detection parameters.
Numerical simulation of phase transition problems with explicit interface tracking
Hu, Yijing; Shi, Qiangqiang; de Almeida, Valmor F.; Li, Xiao-lin
2015-12-19
Phase change is ubiquitous in nature and industrial processes. Started from the Stefan problem, it is a topic with a long history in applied mathematics and sciences and continues to generate outstanding mathematical problems. For instance, the explicit tracking of the Gibbs dividing surface between phases is still a grand challenge. Our work has been motivated by such challenge and here we report on progress made in solving the governing equations of continuum transport in the presence of a moving interface by the front tracking method. The most pressing issue is the accounting of topological changes suffered by the interface between phases wherein break up and/or merge takes place. The underlying physics of topological changes require the incorporation of space-time subscales not at reach at the moment. Therefore we use heuristic geometrical arguments to reconnect phases in space. This heuristic approach provides new insight in various applications and it is extensible to include subscale physics and chemistry in the future. We demonstrate the method on applications such as simulating freezing, melting, dissolution, and precipitation. The later examples also include the coupling of the phase transition solution with the Navier-Stokes equations for the effect of flow convection.
Spatially-explicit models of global tree density
Glick, Henry B.; Bettigole, Charlie; Maynard, Daniel S.; Covey, Kristofer R.; Smith, Jeffrey R.; Crowther, Thomas W.
2016-01-01
Remote sensing and geographic analysis of woody vegetation provide means of evaluating the distribution of natural resources, patterns of biodiversity and ecosystem structure, and socio-economic drivers of resource utilization. While these methods bring geographic datasets with global coverage into our day-to-day analytic spheres, many of the studies that rely on these strategies do not capitalize on the extensive collection of existing field data. We present the methods and maps associated with the first spatially-explicit models of global tree density, which relied on over 420,000 forest inventory field plots from around the world. This research is the result of a collaborative effort engaging over 20 scientists and institutions, and capitalizes on an array of analytical strategies. Our spatial data products offer precise estimates of the number of trees at global and biome scales, but should not be used for local-level estimation. At larger scales, these datasets can contribute valuable insight into resource management, ecological modelling efforts, and the quantification of ecosystem services. PMID:27529613
Global spatially explicit CO2 emission metrics for forest bioenergy
NASA Astrophysics Data System (ADS)
Cherubini, Francesco; Huijbregts, Mark; Kindermann, Georg; van Zelm, Rosalie; van der Velde, Marijn; Stadler, Konstantin; Strømman, Anders Hammer
2016-02-01
Emission metrics aggregate climate impacts of greenhouse gases to common units such as CO2-equivalents (CO2-eq.). Examples include the global warming potential (GWP), the global temperature change potential (GTP) and the absolute sustained emission temperature (aSET). Despite the importance of biomass as a primary energy supplier in existing and future scenarios, emission metrics for CO2 from forest bioenergy are only available on a case-specific basis. Here, we produce global spatially explicit emission metrics for CO2 emissions from forest bioenergy and illustrate their applications to global emissions in 2015 and until 2100 under the RCP8.5 scenario. We obtain global average values of 0.49 ± 0.03 kgCO2-eq. kgCO2-1 (mean ± standard deviation) for GWP, 0.05 ± 0.05 kgCO2-eq. kgCO2-1 for GTP, and 2.14·10-14 ± 0.11·10-14 °C (kg yr-1)-1 for aSET. We explore metric dependencies on temperature, precipitation, biomass turnover times and extraction rates of forest residues. We find relatively high emission metrics with low precipitation, long rotation times and low residue extraction rates. Our results provide a basis for assessing CO2 emissions from forest bioenergy under different indicators and across various spatial and temporal scales.
Electrostatic interactions in charged nanoslits within an explicit solvent theory
NASA Astrophysics Data System (ADS)
Buyukdagli, Sahin
2015-11-01
Within a dipolar Poisson-Boltzmann theory including electrostatic correlations, we consider the effect of explicit solvent structure on solvent and ion partition confined to charged nanopores. We develop a relaxation scheme for the solution of this highly non-linear integro-differential equation for the electrostatic potential. The scheme is an extension of the approach previously introduced for simple planes (Buyukdagli and Blossey 2014 J. Chem. Phys. 140 234903) to nanoslit geometry. We show that the reduced dielectric response of solvent molecules at the membrane walls gives rise to an electric field significantly stronger than the field of the classical Poisson-Boltzmann equation. This peculiarity associated with non-local electrostatic interactions results in turn in an interfacial counterion adsorption layer absent in continuum theories. The observation of this enhanced counterion affinity in the very close vicinity of the interface may have important impacts on nanofluidic transport through charged nanopores. Our results indicate the quantitative inaccuracy of solvent implicit nanofiltration theories in predicting the ionic selectivity of membrane nanopores.
Numerical simulation of phase transition problems with explicit interface tracking
Hu, Yijing; Shi, Qiangqiang; de Almeida, Valmor F.; ...
2015-12-19
Phase change is ubiquitous in nature and industrial processes. Started from the Stefan problem, it is a topic with a long history in applied mathematics and sciences and continues to generate outstanding mathematical problems. For instance, the explicit tracking of the Gibbs dividing surface between phases is still a grand challenge. Our work has been motivated by such challenge and here we report on progress made in solving the governing equations of continuum transport in the presence of a moving interface by the front tracking method. The most pressing issue is the accounting of topological changes suffered by the interfacemore » between phases wherein break up and/or merge takes place. The underlying physics of topological changes require the incorporation of space-time subscales not at reach at the moment. Therefore we use heuristic geometrical arguments to reconnect phases in space. This heuristic approach provides new insight in various applications and it is extensible to include subscale physics and chemistry in the future. We demonstrate the method on applications such as simulating freezing, melting, dissolution, and precipitation. The later examples also include the coupling of the phase transition solution with the Navier-Stokes equations for the effect of flow convection.« less
Two Views About Explicitly Teaching Nature of Science
NASA Astrophysics Data System (ADS)
Duschl, Richard A.; Grandy, Richard
2013-09-01
Our focus is on the effects that dated ideas about the nature of science (NOS) have on curriculum, instruction and assessments. First we examine historical developments in teaching about NOS, beginning with the seminal ideas of James Conant. Next we provide an overview of recent developments in philosophy and cognitive sciences that have shifted NOS characterizations away from general heuristic principles toward cognitive and social elements. Next, we analyze two alternative views regarding `explicitly teaching' NOS in pre-college programs. Version 1 is grounded in teachers presenting `Consensus-based Heuristic Principles' in science lessons and activities. Version 2 is grounded in learners experience of `Building and Refining Model-Based Scientific Practices' in critique and communication enactments that occur in longer immersion units and learning progressions. We argue that Version 2 is to be preferred over Version 1 because it develops the critical epistemic cognitive and social practices that scientists and science learners use when (1) developing and evaluating scientific evidence, explanations and knowledge and (2) critiquing and communicating scientific ideas and information; thereby promoting science literacy.
Flexible explicit but rigid implicit learning in a visuomotor adaptation task.
Bond, Krista M; Taylor, Jordan A
2015-06-01
There is mounting evidence for the idea that performance in a visuomotor rotation task can be supported by both implicit and explicit forms of learning. The implicit component of learning has been well characterized in previous experiments and is thought to arise from the adaptation of an internal model driven by sensorimotor prediction errors. However, the role of explicit learning is less clear, and previous investigations aimed at characterizing the explicit component have relied on indirect measures such as dual-task manipulations, posttests, and descriptive computational models. To address this problem, we developed a new method for directly assaying explicit learning by having participants verbally report their intended aiming direction on each trial. While our previous research employing this method has demonstrated the possibility of measuring explicit learning over the course of training, it was only tested over a limited scope of manipulations common to visuomotor rotation tasks. In the present study, we sought to better characterize explicit and implicit learning over a wider range of task conditions. We tested how explicit and implicit learning change as a function of the specific visual landmarks used to probe explicit learning, the number of training targets, and the size of the rotation. We found that explicit learning was remarkably flexible, responding appropriately to task demands. In contrast, implicit learning was strikingly rigid, with each task condition producing a similar degree of implicit learning. These results suggest that explicit learning is a fundamental component of motor learning and has been overlooked or conflated in previous visuomotor tasks.
How to Introduce the Magnetic Dipole Moment
ERIC Educational Resources Information Center
Bezerra, M.; Kort-Kamp, W. J. M.; Cougo-Pinto, M. V.; Farina, C.
2012-01-01
We show how the concept of the magnetic dipole moment can be introduced in the same way as the concept of the electric dipole moment in introductory courses on electromagnetism. Considering a localized steady current distribution, we make a Taylor expansion directly in the Biot-Savart law to obtain, explicitly, the dominant contribution of the…
Satti, John A.
1980-01-01
A superconducting magnet designed to produce magnetic flux densities of the order of 4 to 5 Webers per square meter is constructed by first forming a cable of a plurality of matrixed superconductor wires with each wire of the plurality insulated from each other one. The cable is shaped into a rectangular cross-section and is wound with tape in an open spiral to create cooling channels. Coils are wound in a calculated pattern in saddle shapes to produce desired fields, such as dipoles, quadrupoles, and the like. Wedges are inserted between adjacent cables as needed to maintain substantially radial placement of the long dimensions of cross sections of the cables. After winding, individual strands in each of the cables are brought out to terminals and are interconnected to place all of the strands in series and to maximize the propagation of a quench by alternating conduction from an inner layer to an outer layer and from top half to bottom half as often as possible. Individual layers are separated from others by spiraled aluminum spacers to facilitate cooling. The wound coil is wrapped with an epoxy tape that is cured by heat and then machined to an interference fit with an outer aluminum pipe which is then affixed securely to the assembled coil by heating it to make a shrink fit. In an alternate embodiment, one wire of the cable is made of copper or the like to be heated externally to propagate a quench.
Tribology of magnetic storage systems
NASA Technical Reports Server (NTRS)
Bhushan, Bharat
1992-01-01
The construction and the materials used in different magnetic storage devices are defined. The theories of friction and adhesion, interface temperatures, wear, and solid-liquid lubrication relevant to magnetic storage systems are presented. Experimental data are presented wherever possible to support the relevant theories advanced.
Magnetic conditioning in superfluid
Caspi, S.
1988-08-01
Improvements in superconducting magnet technology have reduced to a handful the number of training quenches typical of dipole magnets. The number of training quenches in long (17 m) and short (1--2 m) SSC magnets are now about the same (operating at 6.6 tesla and 4.4 K). Yet the steps necessary to totally eliminate training are in the future RandD plans for magnet construction and conductor motion prevention. The accepted hypothesis is that Lorentz forces and poor mechanical properties of superconducting cables are the cause of conductor motion. Conductor motion reduces the stored energy in the cable by converting it into heat. The small amount of heat generated (millijoules) during motion is usually enough to quench the magnet when it is close to short sample. During training, the magnet performance normally improves with the number of quenches. It is not the quench itself that improves magnet performance but rather the fact that once conductor motion has occurred it will probably not repeat itself unless subjected to higher forces. Conditioning is a process that enables the magnet to reduce its stored energy without causing a premature quench. During the conditioning process the magnet is further cooled from its operating temperature of 4.4 K to 1.8 K by converting He I into He II. As a result the magnet is placed in a state where it has excess stability as well as excellent heat transfer capabilities. Although this does not eliminate motion, if the magnet is now cycled to /approximately/10% above its operating field at 4.4 K (which is above short sample) the excess stability should be enough to prevent quenching and reduce the probability of conductor motion and training once the magnet has been warmed back up to its operating temperature of 4.4 K. 3 refs., 5 figs.
Halbach, K.
1986-07-01
A number of basic conceptual designs are explained for magnet systems that use permanent magnet materials. Included are iron free multipoles and hybrid magnets. Also appended is a discussion of the manufacturing process and magnetic properties of some permanent magnet materials. (LEW)
Individual differences in explicit and implicit visuomotor learning and working memory capacity
Christou, Antonios I.; Miall, R. Chris; McNab, Fiona; Galea, Joseph M.
2016-01-01
The theoretical basis for the association between high working memory capacity (WMC) and enhanced visuomotor adaptation is unknown. Visuomotor adaptation involves interplay between explicit and implicit systems. We examined whether the positive association between adaptation and WMC is specific to the explicit component of adaptation. Experiment 1 replicated the positive correlation between WMC and adaptation, but revealed this was specific to the explicit component of adaptation, and apparently driven by a sub-group of participants who did not show any explicit adaptation in the correct direction. A negative correlation was observed between WMC and implicit learning. Experiments 2 and 3 showed that when the task restricted the development of an explicit strategy, high WMC was no longer associated with enhanced adaptation. This work reveals that the benefit of high WMC is specifically linked to an individual’s capacity to use an explicit strategy. It also reveals an important contribution of individual differences in determining how adaptation is performed. PMID:27824129
Attitudinal effects of degrading themes and sexual explicitness in video materials.
Golde, J A; Strassberg, D S; Turner, C M; Lowe, K
2000-07-01
This study examined the independent and interactive effects of sexual explicitness and degrading themes toward women on mens' attitudes following exposure to video presentations of male-female interactions. Subjects were 83 male college students who viewed video vignettes under one of four stimulus conditions: (a) sexually explicit/degrading, (b) sexually explicit/nondegrading, (c) nonexplicit/degrading, and (d) nonexplicit/nondegrading. Results revealed that men exposed to degrading material, regardless of explicitness, were significantly more likely to express attitudes supportive of rape, while explicitness had no significant main or interactive effect on these attitudes. Further, the interaction of explicitness with degradation was found to impact scores on a measure of sexual callousness. Theoretical and clinical implications of these findings are discussed.
Karpinski, Andrew; Steinman, Ross B; Hilton, James L
2005-07-01
The authors examined attitude importance as a moderator of the relationship between the Implicit Association Test (IAT) and explicit attitude measures. In Study 1 (N = 194), as ratings of attitude importance regarding the 2000 presidential election increased, the strength of the relationship between a Bush-Gore IAT and explicit attitude measures also increased. Study 2 provided a conceptual replication of these results using attitudes toward Coke and Pepsi (N = 112). In addition, across both studies, explicit attitude measures were better predictors of deliberative behaviors than IAT scores. In Study 3 (N = 77), the authors examined the role of elaboration as a mechanism by which attitude importance may moderate IAT-explicit attitude correlations. As predicted, increased elaboration resulted in stronger IAT-explicit attitude correlations. Other possible mechanisms by which attitude importance may moderate the IAT-explicit attitude relationship also are discussed.
Explicit contact modeling for surgical computer guidance and simulation
NASA Astrophysics Data System (ADS)
Johnsen, S. F.; Taylor, Z. A.; Clarkson, M.; Thompson, S.; Hu, M.; Gurusamy, K.; Davidson, B.; Hawkes, D. J.; Ourselin, S.
2012-02-01
Realistic modelling of mechanical interactions between tissues is an important part of surgical simulation, and may become a valuable asset in surgical computer guidance. Unfortunately, it is also computationally very demanding. Explicit matrix-free FEM solvers have been shown to be a good choice for fast tissue simulation, however little work has been done on contact algorithms for such FEM solvers. This work introduces such an algorithm that is capable of handling both deformable-deformable (soft-tissue interacting with soft-tissue) and deformable-rigid (e.g. soft-tissue interacting with surgical instruments) contacts. The proposed algorithm employs responses computed with a fully matrix-free, virtual node-based version of the model first used by Taylor and Flanagan in PRONTO3D. For contact detection, a bounding-volume hierarchy (BVH) capable of identifying self collisions is introduced. The proposed BVH generation and update strategies comprise novel heuristics to minimise the number of bounding volumes visited in hierarchy update and collision detection. Aside from speed, stability was a major objective in the development of the algorithm, hence a novel method for computation of response forces from C0-continuous normals, and a gradual application of response forces from rate constraints has been devised and incorporated in the scheme. The continuity of the surface normals has advantages particularly in applications such as sliding over irregular surfaces, which occurs, e.g., in simulated breathing. The effectiveness of the scheme is demonstrated on a number of meshes derived from medical image data and artificial test cases.
Global spatially explicit CO2 emission metrics for forest bioenergy
Cherubini, Francesco; Huijbregts, Mark; Kindermann, Georg; Van Zelm, Rosalie; Van Der Velde, Marijn; Stadler, Konstantin; Strømman, Anders Hammer
2016-01-01
Emission metrics aggregate climate impacts of greenhouse gases to common units such as CO2-equivalents (CO2-eq.). Examples include the global warming potential (GWP), the global temperature change potential (GTP) and the absolute sustained emission temperature (aSET). Despite the importance of biomass as a primary energy supplier in existing and future scenarios, emission metrics for CO2 from forest bioenergy are only available on a case-specific basis. Here, we produce global spatially explicit emission metrics for CO2 emissions from forest bioenergy and illustrate their applications to global emissions in 2015 and until 2100 under the RCP8.5 scenario. We obtain global average values of 0.49 ± 0.03 kgCO2-eq. kgCO2−1 (mean ± standard deviation) for GWP, 0.05 ± 0.05 kgCO2-eq. kgCO2−1 for GTP, and 2.14·10−14 ± 0.11·10−14 °C (kg yr−1)−1 for aSET. We explore metric dependencies on temperature, precipitation, biomass turnover times and extraction rates of forest residues. We find relatively high emission metrics with low precipitation, long rotation times and low residue extraction rates. Our results provide a basis for assessing CO2 emissions from forest bioenergy under different indicators and across various spatial and temporal scales. PMID:26830755
Landscape equivalency analysis: methodology for estimating spatially explicit biodiversity credits.
Bruggeman, Douglas J; Jones, Michael L; Lupi, Frank; Scribner, Kim T
2005-10-01
We propose a biodiversity credit system for trading endangered species habitat designed to minimize and reverse the negative effects of habitat loss and fragmentation, the leading cause of species endangerment in the United States. Given the increasing demand for land, approaches that explicitly balance economic goals against conservation goals are required. The Endangered Species Act balances these conflicts based on the cost to replace habitat. Conservation banking is a means to manage this balance, and we argue for its use to mitigate the effects of habitat fragmentation. Mitigating the effects of land development on biodiversity requires decisions that recognize regional ecological effects resulting from local economic decisions. We propose Landscape Equivalency Analysis (LEA), a landscape-scale approach similar to HEA, as an accounting system to calculate conservation banking credits so that habitat trades do not exacerbate regional ecological effects of local decisions. Credits purchased by public agencies or NGOs for purposes other than mitigating a take create a net investment in natural capital leading to habitat defragmentation. Credits calculated by LEA use metapopulation genetic theory to estimate sustainability criteria against which all trades are judged. The approach is rooted in well-accepted ecological, evolutionary, and economic theory, which helps compensate for the degree of uncertainty regarding the effects of habitat loss and fragmentation on endangered species. LEA requires application of greater scientific rigor than typically applied to endangered species management on private lands but provides an objective, conceptually sound basis for achieving the often conflicting goals of economic efficiency and long-term ecological sustainability.
Diffusive Models of Membrane Permeation with Explicit Orientational Freedom.
Comer, Jeffrey; Schulten, Klaus; Chipot, Christophe
2014-07-08
Accurate calculation of permeabilities from first-principles has been a long-standing challenge for computer simulations, notably in the context of drug discovery, as a route to predict the propensity of small, organic molecules to spontaneously translocate biological membranes. Of equal importance is the understanding of the permeation process and the pathway followed by the permeant from the aqueous medium to the interior of the lipid bilayer, and back out again. A convenient framework for the computation of permeabilities is provided by the solubility-diffusion model, which requires knowledge of the underlying free-energy and diffusivity landscapes. Here, we develop a formalism that includes an explicit description of the orientational motion of the solute as it diffuses across the membrane. Toward this end, we have generalized a recently proposed method that reconciles thermodynamics and kinetics in importance-sampling simulations by means of a Bayesian-inference scheme to reverse-solve the underlying Smoluchowski equation. Performance of the proposed formalism is examined in the model cases of a water and an ethanol molecule crossing a fully hydrated lipid bilayer. Our analysis reveals a conspicuous dependence of the free-energy and rotational diffusivity on the orientation of ethanol when it lies within the headgroup region of the bilayer. Specifically, orientations for which the hydroxyl group lies among the polar lipid head groups, while the ethyl group recedes toward the hydrophobic interior are associated with free-energy minima ∼2kBT deep, as well as significantly slower orientational kinetics compared to the bulk solution or the core of the bilayer. The conspicuous orientational anisotropy of ethanol at the aqueous interface is suggestive of a complete rotation of the permeant as it crosses the hydrophobic interior of the membrane.
Quantum mechanical force field for water with explicit electronic polarization
Han, Jaebeom; Mazack, Michael J. M.; Zhang, Peng; Truhlar, Donald G.; Gao, Jiali
2013-01-01
A quantum mechanical force field (QMFF) for water is described. Unlike traditional approaches that use quantum mechanical results and experimental data to parameterize empirical potential energy functions, the present QMFF uses a quantum mechanical framework to represent intramolecular and intermolecular interactions in an entire condensed-phase system. In particular, the internal energy terms used in molecular mechanics are replaced by a quantum mechanical formalism that naturally includes electronic polarization due to intermolecular interactions and its effects on the force constants of the intramolecular force field. As a quantum mechanical force field, both intermolecular interactions and the Hamiltonian describing the individual molecular fragments can be parameterized to strive for accuracy and computational efficiency. In this work, we introduce a polarizable molecular orbital model Hamiltonian for water and for oxygen- and hydrogen-containing compounds, whereas the electrostatic potential responsible for intermolecular interactions in the liquid and in solution is modeled by a three-point charge representation that realistically reproduces the total molecular dipole moment and the local hybridization contributions. The present QMFF for water, which is called the XP3P (explicit polarization with three-point-charge potential) model, is suitable for modeling both gas-phase clusters and liquid water. The paper demonstrates the performance of the XP3P model for water and proton clusters and the properties of the pure liquid from about 900 × 106 self-consistent-field calculations on a periodic system consisting of 267 water molecules. The unusual dipole derivative behavior of water, which is incorrectly modeled in molecular mechanics, is naturally reproduced as a result of an electronic structural treatment of chemical bonding by XP3P. We anticipate that the XP3P model will be useful for studying proton transport in solution and solid phases as well as across
Quantum mechanical force field for water with explicit electronic polarization.
Han, Jaebeom; Mazack, Michael J M; Zhang, Peng; Truhlar, Donald G; Gao, Jiali
2013-08-07
A quantum mechanical force field (QMFF) for water is described. Unlike traditional approaches that use quantum mechanical results and experimental data to parameterize empirical potential energy functions, the present QMFF uses a quantum mechanical framework to represent intramolecular and intermolecular interactions in an entire condensed-phase system. In particular, the internal energy terms used in molecular mechanics are replaced by a quantum mechanical formalism that naturally includes electronic polarization due to intermolecular interactions and its effects on the force constants of the intramolecular force field. As a quantum mechanical force field, both intermolecular interactions and the Hamiltonian describing the individual molecular fragments can be parameterized to strive for accuracy and computational efficiency. In this work, we introduce a polarizable molecular orbital model Hamiltonian for water and for oxygen- and hydrogen-containing compounds, whereas the electrostatic potential responsible for intermolecular interactions in the liquid and in solution is modeled by a three-point charge representation that realistically reproduces the total molecular dipole moment and the local hybridization contributions. The present QMFF for water, which is called the XP3P (explicit polarization with three-point-charge potential) model, is suitable for modeling both gas-phase clusters and liquid water. The paper demonstrates the performance of the XP3P model for water and proton clusters and the properties of the pure liquid from about 900 × 10(6) self-consistent-field calculations on a periodic system consisting of 267 water molecules. The unusual dipole derivative behavior of water, which is incorrectly modeled in molecular mechanics, is naturally reproduced as a result of an electronic structural treatment of chemical bonding by XP3P. We anticipate that the XP3P model will be useful for studying proton transport in solution and solid phases as well as across
Intrinsic magnetization of antiferromagnetic textures
NASA Astrophysics Data System (ADS)
Tveten, Erlend G.; Müller, Tristan; Linder, Jacob; Brataas, Arne
2016-03-01
Antiferromagnets (AFMs) exhibit intrinsic magnetization when the order parameter spatially varies. This intrinsic spin is present even at equilibrium and can be interpreted as a twisting of the homogeneous AFM into a state with a finite spin. Because magnetic moments couple directly to external magnetic fields, the intrinsic magnetization can alter the dynamics of antiferromagnetic textures under such influence. Starting from the discrete Heisenberg model, we derive the continuum limit of the free energy of AFMs in the exchange approximation and explicitly rederive that the spatial variation of the antiferromagnetic order parameter is associated with an intrinsic magnetization density. We calculate the magnetization profile of a domain wall and discuss how the intrinsic magnetization reacts to external forces. We show conclusively, both analytically and numerically, that a spatially inhomogeneous magnetic field can move and control the position of domain walls in AFMs. By comparing our model to a commonly used alternative parametrization procedure for the continuum fields, we show that the physical interpretations of these fields depend critically on the choice of parametrization procedure for the discrete-to-continuous transition. This can explain why a significant amount of recent studies of the dynamics of AFMs, including effective models that describe the motion of antiferromagnetic domain walls, have neglected the intrinsic spin of the textured order parameter.
Kirol, L.D.
1987-02-11
A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation. 5 figs.
Kirol, Lance D.
1988-01-01
A rotary magnetic heat pump constructed without flow seals or segmented rotor accomplishes recuperation and regeneration by using split flow paths. Heat exchange fluid pumped through heat exchangers and returned to the heat pump splits into two flow components: one flowing counter to the rotor rotation and one flowing with the rotation.
ERIC Educational Resources Information Center
Gabel, Dorothy; And Others
1992-01-01
Chemistry can be described on three levels: sensory, molecular, and symbolic. Proposes a particle approach to teaching chemistry that uses magnets to aid students construct molecular models and solve particle problems. Includes examples of Johnstone's model of chemistry phenomena, a problem worksheet, and a student concept mastery sheet. (MDH)
Locally-Adaptive, Spatially-Explicit Projection of U.S. Population for 2030 and 2050
McKee, Jacob J.; Rose, Amy N.; Bright, Eddie A.; Huynh, Timmy N.; Bhaduri, Budhendra L.
2015-02-03
Localized adverse events, including natural hazards, epidemiological events, and human conflict, underscore the criticality of quantifying and mapping current population. Moreover, knowing the spatial distribution of future population allows for increased preparation in the event of an emergency. Building on the spatial interpolation technique previously developed for high resolution population distribution data (LandScan Global and LandScan USA), we have constructed an empirically-informed spatial distribution of the projected population of the contiguous U.S. for 2030 and 2050. Whereas most current large-scale, spatially explicit population projections typically rely on a population gravity model to determine areas of future growth, our projection model departs from these by accounting for multiple components that affect population distribution. Modelled variables, which included land cover, slope, distances to larger cities, and a moving average of current population, were locally adaptive and geographically varying. The resulting weighted surface was used to determine which areas had the greatest likelihood for future population change. Population projections of county level numbers were developed using a modified version of the U.S. Census s projection methodology with the U.S. Census s official projection as the benchmark. Applications of our model include, but are not limited to, suitability modelling, service area planning for governmental agencies, consequence assessment, mitigation planning and implementation, and assessment of spatially vulnerable populations.
Locally-Adaptive, Spatially-Explicit Projection of U.S. Population for 2030 and 2050
McKee, Jacob J.; Rose, Amy N.; Bright, Eddie A.; ...
2015-02-03
Localized adverse events, including natural hazards, epidemiological events, and human conflict, underscore the criticality of quantifying and mapping current population. Moreover, knowing the spatial distribution of future population allows for increased preparation in the event of an emergency. Building on the spatial interpolation technique previously developed for high resolution population distribution data (LandScan Global and LandScan USA), we have constructed an empirically-informed spatial distribution of the projected population of the contiguous U.S. for 2030 and 2050. Whereas most current large-scale, spatially explicit population projections typically rely on a population gravity model to determine areas of future growth, our projection modelmore » departs from these by accounting for multiple components that affect population distribution. Modelled variables, which included land cover, slope, distances to larger cities, and a moving average of current population, were locally adaptive and geographically varying. The resulting weighted surface was used to determine which areas had the greatest likelihood for future population change. Population projections of county level numbers were developed using a modified version of the U.S. Census s projection methodology with the U.S. Census s official projection as the benchmark. Applications of our model include, but are not limited to, suitability modelling, service area planning for governmental agencies, consequence assessment, mitigation planning and implementation, and assessment of spatially vulnerable populations.« less
Hilpert, Markus
2010-11-01
In a preceding paper, we derived analytical solutions for the displacement of a gas by a liquid in horizontal and inclined capillary tubes where the tube inlet is connected to a liquid reservoir of constant pressure. We considered quite general models for the dynamic contact angle and were able to derive implicit equations for the velocity of the gas-liquid interface. These solutions allowed us to identify five different flow scenarios for liquid withdrawal that differed in the direction of flow and the sign of the acceleration of the gas-liquid interface. In this paper, we consider the special case where the dynamic contact angle is determined by a nonequilibrium Young force that depends linearly on the capillary number. Thus we can derive explicit and the more traditional implicit analytical solutions for both the position and the velocity of the gas-liquid interface. We also construct diagrams that allow us to predict which of the five flow scenarios will occur depending on the nondimensional parameters that define the problem. The diagrams can be combined with diagrams previously obtained for infiltration and the entire parameter space subdivided into regions that are associated with either liquid withdrawal, liquid infiltration, or metastable and stable equilibrium states. Our solutions are also valid within the limit where the contact angle is constant.
Software with partial functions: Automating correctness proofs via nonstrict explicit domains
Yakhnis, A.; Yakhnis, V.; Winter, V.
1996-07-30
As our society becomes technologically more complex, computers are being used in greater and greater numbers of high consequence systems. Giving a machine control over the lives of humans can be disturbing, especially if the software that is run on such a machine has bugs. Formal reasoning is one of the most powerful techniques available to demonstrate the correctness of a piece of software. When reasoning about software and its development, one frequently encounters expressions that contain partial functions. As might be expected, the presence of partial functions introduces an additional dimension of difficulty to the reasoning framework. This difficulty produces an especially strong impact in the case of high consequence systems. An ability to use formal methods for constructing software is essential if we want to obtain greater confidence in such systems through formal reasoning. This is only reasonable under automation of software development and verification. However, the ubiquitous presence of partial functions prevents a uniform application to software of any tools not specifically accounting for partial functions. In this paper we will describe a framework for reasoning about software, based on the nonstrict explicit domain approach, that is applicable to a large class of software/hardware systems. In this framework the Hoare triples containing partial functions can be reasoned about automatically in a well-defined and uniform manner.
Lewison, R.L.; Carter, J.
2004-01-01
Herbivore foraging theories have been developed for and tested on herbivores across a range of sizes. Due to logistical constraints, however, little research has focused on foraging behavior of megaherbivores. Here we present a research approach that explores megaherbivore foraging behavior, and assesses the applicability of foraging theories developed on smaller herbivores to megafauna. With simulation models as reference points for the analysis of empirical data, we investigate foraging strategies of the common hippopotamus (Hippopotamus amphibius). Using a spatially explicit individual based foraging model, we apply traditional herbivore foraging strategies to a model hippopotamus, compare model output, and then relate these results to field data from wild hippopotami. Hippopotami appear to employ foraging strategies that respond to vegetation characteristics, such as vegetation quality, as well as spatial reference information, namely distance to a water source. Model predictions, field observations, and comparisons of the two support that hippopotami generally conform to the central place foraging construct. These analyses point to the applicability of general herbivore foraging concepts to megaherbivores, but also point to important differences between hippopotami and other herbivores. Our synergistic approach of models as reference points for empirical data highlights a useful method of behavioral analysis for hard-to-study megafauna. ?? 2003 Elsevier B.V. All rights reserved.
A class of high resolution explicit and implicit shock-capturing methods
NASA Technical Reports Server (NTRS)
Yee, H. C.
1989-01-01
An attempt is made to give a unified and generalized formulation of a class of high resolution, explicit and implicit shock capturing methods, and to illustrate their versatility in various steady and unsteady complex shock wave computations. Included is a systematic review of the basic design principle of the various related numerical methods. Special emphasis is on the construction of the basis nonlinear, spatially second and third order schemes for nonlinear scalar hyperbolic conservation laws and the methods of extending these nonlinear scalar schemes to nonlinear systems via the approximate Riemann solvers and the flux vector splitting approaches. Generalization of these methods to efficiently include equilibrium real gases and large systems of nonequilibrium flows are discussed. Some issues concerning the applicability of these methods that were designed for homogeneous hyperbolic conservation laws to problems containing stiff source terms and shock waves are also included. The performance of some of these schemes is illustrated by numerical examples for 1-, 2- and 3-dimensional gas dynamics problems.
Taylor, Mark P; Ye, Yuting; Adhikari, Shishir R
2015-11-28
The conformation of a polymer chain in solution is coupled to the local structure of the surrounding solvent and can undergo large changes in response to variations in solvent density and temperature. The many-body effects of solvent on the structure of an n-mer polymer chain can be formally mapped to an exact n-body solvation potential. Here, we use a pair decomposition of this n-body potential to construct a set of two-body potentials for a Lennard-Jones (LJ) polymer chain in explicit LJ solvent. The solvation potentials are built from numerically exact results for 5-mer chains in solvent combined with an approximate asymptotic expression for the solvation potential between sites that are distant along the chain backbone. These potentials map the many-body chain-in-solvent problem to a few-body single-chain problem and can be used to study a chain of arbitrary length, thereby dramatically reducing the computational complexity of the polymer chain-in-solvent problem. We have constructed solvation potentials at a large number of state points across the LJ solvent phase diagram including the vapor, liquid, and super-critical regions. We use these solvation potentials in single-chain Monte Carlo (MC) simulations with n ≤ 800 to determine the size, intramolecular structure, and scaling behavior of chains in solvent. To assess our results, we have carried out full chain-in-solvent MC simulations (with n ≤ 100) and find that our solvation potential approach is quantitatively accurate for a wide range of solvent conditions for these chain lengths.
A Class of High-Resolution Explicit and Implicit Shock-Capturing Methods
NASA Technical Reports Server (NTRS)
Yee, H. C.
1994-01-01
The development of shock-capturing finite difference methods for hyperbolic conservation laws has been a rapidly growing area for the last decade. Many of the fundamental concepts, state-of-the-art developments and applications to fluid dynamics problems can only be found in meeting proceedings, scientific journals and internal reports. This paper attempts to give a unified and generalized formulation of a class of high-resolution, explicit and implicit shock capturing methods, and to illustrate their versatility in various steady and unsteady complex shock waves, perfect gases, equilibrium real gases and nonequilibrium flow computations. These numerical methods are formulated for the purpose of ease and efficient implementation into a practical computer code. The various constructions of high-resolution shock-capturing methods fall nicely into the present framework and a computer code can be implemented with the various methods as separate modules. Included is a systematic overview of the basic design principle of the various related numerical methods. Special emphasis will be on the construction of the basic nonlinear, spatially second and third-order schemes for nonlinear scalar hyperbolic conservation laws and the methods of extending these nonlinear scalar schemes to nonlinear systems via the approximate Riemann solvers and flux-vector splitting approaches. Generalization of these methods to efficiently include real gases and large systems of nonequilibrium flows will be discussed. Some perbolic conservation laws to problems containing stiff source terms and terms and shock waves are also included. The performance of some of these schemes is illustrated by numerical examples for one-, two- and three-dimensional gas-dynamics problems. The use of the Lax-Friedrichs numerical flux to obtain high-resolution shock-capturing schemes is generalized. This method can be extended to nonlinear systems of equations without the use of Riemann solvers or flux
Solution of dynamic contact problems by implicit/explicit methods. Final report
Salveson, M.W.; Taylor, R.L.
1996-10-14
The solution of dynamic contact problems within an explicit finite element program such as the LLNL DYNA programs is addressed in the report. The approach is to represent the solution for the deformation of bodies using the explicit algorithm but to solve the contact part of the problem using an implicit approach. Thus, the contact conditions at the next solution state are considered when computing the acceleration state for each explicit time step.
Explicit Not Implicit Preferences Predict Conservation Intentions for Endangered Species and Biomes.
Echeverri, Alejandra; Callahan, Megan M; Chan, Kai M A; Satterfield, Terre; Zhao, Jiaying
2017-01-01
Conservation of biodiversity is determined in part by human preferences. Preferences relevant to conservation have been examined largely via explicit measures (e.g., a self-reported degree of liking), with implicit measures (e.g., preconscious, automatic evaluations) receiving relatively less attention. This is the case despite psychological evidence from other contexts that implicit preferences are more informative of behavior. Thus, the type of measure that predicts conservation intentions for biodiversity is unknown. We conducted three studies to examine conservation intentions in light of people's explicit and implicit preferences toward four endangered species (sea otter, American badger, caribou, yellow-breasted chat) and four biomes (forest, ocean, grassland, tundra). In Study 1 (n = 55), we found that people implicitly preferred caribou most, but explicitly preferred sea otter most, with a significant multiple regression where participants' explicit preferences dictated their stated intended donations for conservation of each species. In Study 2 (n = 57) we found that people implicitly and explicitly preferred forest and ocean over grassland and tundra. Explicit rather than implicit preferences predicted the intended donation for conservation of the ocean biome. Study 3 involved a broader online sample of participants (n = 463) and also found that explicit preferences dictated the intended donations for conservation of biomes and species. Our findings reveal discrepancies between implicit and explicit preferences toward species, but not toward biomes. Importantly, the results demonstrate that explicit rather than implicit preferences predict conservation intentions for biodiversity. The current findings have several implications for conservation and the communication of biodiversity initiatives.
A magnetic filter with permanent magnets on the basis of rare earths
NASA Astrophysics Data System (ADS)
Žežulka, Václav; Straka, Pavel; Mucha, Pavel
2004-01-01
The article presents the development and construction of a magnetic filter based on the HGMS principle with permanent magnets. It is aimed especially at the assembly of the magnetic circuit using magnets from the material NdFeB. The way of the construction of large magnetic blocks, their magnetization and assembly are described. Further, it contains the measured values of magnetic induction in the middle of the air gap as a function of the width of this gap and of the height of the magnetic blocks in question, as well as the corresponding graphic representation. The high values of the magnetic induction obtained together with favourable price are sufficient reasons for the employment of this type of magnetic circuit in various applications.
NASA Technical Reports Server (NTRS)
Pasley, R. L.; Barton, J. R.
1973-01-01
Magnetic techniques are described for the nondestructive evaluation of defects in materials. The physical principles, and the magnetic-particle method are discussed along with magnetic-hysteresis measurements and electric current perturbations.
Collisionless Coupling between Explosive Debris Plasma and Magnetized Ambient Plasma
NASA Astrophysics Data System (ADS)
Bondarenko, Anton
2016-10-01
The explosive expansion of a dense debris plasma cloud into relatively tenuous, magnetized, ambient plasma characterizes a wide variety of astrophysical and space phenomena, including supernova remnants, interplanetary coronal mass ejections, and ionospheric explosions. In these rarified environments, collective electromagnetic processes rather than Coulomb collisions typically mediate the transfer of momentum and energy from the debris plasma to the ambient plasma. In an effort to better understand the detailed physics of collisionless coupling mechanisms in a reproducible laboratory setting, the present research jointly utilizes the Large Plasma Device (LAPD) and the Phoenix laser facility at UCLA to study the super-Alfvénic, quasi-perpendicular expansion of laser-produced carbon (C) and hydrogen (H) debris plasma through preformed, magnetized helium (He) ambient plasma via a variety of diagnostics, including emission spectroscopy, wavelength-filtered imaging, and magnetic field induction probes. Large Doppler shifts detected in a He II ion spectral line directly indicate initial ambient ion acceleration transverse to both the debris plasma flow and the background magnetic field, indicative of a fundamental process known as Larmor coupling. Characterization of the laser-produced debris plasma via a radiation-hydrodynamics code permits an explicit calculation of the laminar electric field in the framework of a ``hybrid'' model (kinetic ions, charge-neutralizing massless fluid electrons), thus allowing for a simulation of the initial response of a distribution of He II test ions. A synthetic Doppler-shifted spectrum constructed from the simulated velocity distribution of the accelerated test ions excellently reproduces the spectroscopic measurements, confirming the role of Larmor coupling in the debris-ambient interaction.
NASA Astrophysics Data System (ADS)
Schouten, Hans; Tivey, Maurice A.; Fornari, Daniel J.; Cochran, James R.
1999-05-01
The central anomaly magnetization high (CAMH) is a zone of high crustal magnetization centered on the axis of the East Pacific Rise (EPR) and many other segments of the global mid-ocean ridge (MOR). The CAMH is thought to reflect the presence of recently emplaced and highly magnetic lavas. Forward models show that the complicated character of the near-bottom CAMH can be successfully reproduced by the convolution of a lava deposition distribution with a lava magnetization function that describes the variation in lava magnetization intensity with age. This lava magnetization function is the product of geomagnetic paleofield intensity, which has increased by a factor of 2 over the last 40 kyr, and low-temperature alteration which decreases the remanence of lava with exposure to seawater. The success of the forward modeling justifies the inverse approach: deconvolution of the magnetic data for lava distribution and integration of that distribution for magnetic layer thickness. This approach is tested on two near-bottom magnetic profiles AL2767 and AL2771, collected using Alvin across the EPR axis at 9°31'N and 9°50'N. Our analysis of these data produces an estimate of the relative thickness of the magnetic lava layer which is remarkably consistent with existing multichannel estimates of layer 2A thickness from lines CDP31 and CDP27. The similarity between magnetic layer and seismic layer 2A at the 9°-10°N segment of the EPR crest provides independent support to the notion that seismic layer 2A in young oceanic crust represents the highly magnetic lava layer, and that the velocity gradient at the base of layer 2A is related to the increasing number of higher-velocity dikes with depth in the lava-dike transition zone. The near-bottom magnetic anomaly character of the CAMH is a powerful indicator of the emplacement history of upper crust at MORs which allows prediction of the relative thickness and architecture of the extrusive lavas independent of other constraints.
A magnetic fluid microdevice using insect wings
NASA Astrophysics Data System (ADS)
Sudo, S.; Tsuyuki, K.; Yano, T.; Takagi, K.
2008-05-01
A magnetic fluid microdevice using Diptera insect wings is proposed and constructed. The magnetic fluid device is composed of insect wings, a small permanent magnet, coil, and kerosene-based magnetic fluid. First, the structural properties of insect wings are studied through measurements of certain morphological parameters. Secondly, the novel type of microwind energy converter is constructed. Thirdly, the power generation characteristics of the magnetic fluid microdevice using insect wings are examined. It is found that the output power is roughly proportional to the cube of the airflow velocity.
Embodying emotions: making transactions explicit in science learning contexts
NASA Astrophysics Data System (ADS)
Milne, Catherine; Rubin, Kayla
2011-09-01
In this Forum paper we synthesize some of the main ideas from three papers: Auli Orlander and Per-Olof Wickman's (Cult Stud Sci 6, 2011), Bodily experiences in secondary school biology, Roger Sages' (Cult Stud Sci Educ 6, 2011), About Descartes: Uses and misuses, and Steve Alsop's (Cult Stud Sci Educ 6, 2011), The body bites back! These papers challenged us to identify how emotions functioned as elements of bodily experiences in classroom transactions and why science teachers often are not responsive to students' emoting. We also explored how teachers making use of curriculum and companion meanings could support the construction of learning environments that more productively support students' science learning.
Strickland, G.; Horn, F.L.; White, H.T.
1960-09-27
A pump which utilizes the fluid being pumped through it as its lubricating fluid is described. This is achieved by means of an improved bearing construction in a pump of the enclosed or canned rotor type. At the outlet end of the pump, adjacent to an impeller mechanism, there is a bypass which conveys some of the pumped fluid to a chamber at the inlet end of the pump. After this chamber becomes full, the pumped fluid passes through fixed orifices in the top of the chamber and exerts a thrust on the inlet end of the pump rotor. Lubrication of the rotor shaft is accomplished by passing the pumped fluid through a bypass at the outlet end of the rotor shaft. This bypass conveys Pumped fluid to a cooling means and then to grooves on the surface of the rotor shait, thus lubricating the shaft.
NASA Astrophysics Data System (ADS)
Blanton, Patricia
2003-02-01
Schools are expected to lay the foundation upon which knowledge can be built and equip students with the tools necessary to accomplish the construction. The role of the teacher in this building process is crucial to the type of structure the student can build. Whether you call it constructivism, discussion teaching, project-based learning, inquiry learning, or any of the other names given to the instructional strategies being suggested by education researchers, the key is getting students to become active participants in the process. While some students may be able to learn from eloquently delivered lectures and dynamic demonstrations, the majority of students cannot effectively retain and apply ideas communicated in this manner.
ERIC Educational Resources Information Center
Wida, Sam
1992-01-01
Uses extremely strong neodymium magnets to demonstrate several principles of physics including electromagnetic induction, Lenz's Law, domain theory, demagnetization, the Curie point, and magnetic flux lines. (MDH)
Cotangent bundle quantization: entangling of metric and magnetic field
NASA Astrophysics Data System (ADS)
Karasev, M. V.; Osborn, T. A.
2005-10-01
For manifolds \\mathcal{M} of noncompact type endowed with an affine connection (for example, the Levi-Civita connection) and a closed 2-form (magnetic field), we define a Hilbert algebra structure in the space L^2(T^*\\!{\\mathcal{M}}) and construct an irreducible representation of this algebra in L^2(\\mathcal{M}) . This algebra is automatically extended to polynomial in momenta functions and distributions. Under some natural conditions, this algebra is unique. The non-commutative product over T^*\\!{\\mathcal{M}} is given by an explicit integral formula. This product is exact (not formal) and is expressed in invariant geometrical terms. Our analysis reveals that this product has a front, which is described in terms of geodesic triangles in \\mathcal{M} . The quantization of δ-functions induces a family of symplectic reflections in T^*\\!{\\mathcal{M}} and generates a magneto-geodesic connection Γ on T^*\\mathcal{M} . This symplectic connection entangles, on the phase space level, the original affine structure on \\mathcal{M} and the magnetic field. In the classical approximation, the planck2-part of the quantum product contains the Ricci curvature of Γ and a magneto-geodesic coupling tensor.
Wang, C-X. )
2012-04-25
Optimization of nonlinear driving terms have become a useful tool for designing storage rings, especially modern light sources where the strong nonlinearity is dominated by the large chromatic effects of quadrupoles and strong sextupoles for chromaticity control. The Lie algebraic method is well known for computing such driving terms. However, it appears that there was a lack of explicit formulas in the public domain for such computation, resulting in uncertainty and/or inconsistency in widely used codes. This note presents explicit formulas for driving terms due to sextupoles and chromatic effects of quadrupoles, which can be considered as thin elements. The computation is accurate to the 4th-order Hamiltonian and 2nd-order in terms of magnet parameters. The results given here are the same as the APS internal note AOP-TN-2009-020. This internal nte has been revised and published here as a Light Source Note in order to get this information into the public domain, since both ELEGANT and OPA are using these formulas.
Chen, Chunxia; Depa, Praveen; Sakai, Victoria García; Maranas, Janna K; Lynn, Jeffrey W; Peral, Inmaculada; Copley, John R D
2006-06-21
We compare static and dynamic properties obtained from three levels of modeling for molecular dynamics simulation of poly(ethylene oxide) (PEO). Neutron scattering data are used as a test of each model's accuracy. The three simulation models are an explicit atom (EA) model (all the hydrogens are taken into account explicitly), a united atom (UA) model (CH(2) and CH(3) groups are considered as a single unit), and a coarse-grained (CG) model (six united atoms are taken as one bead). All three models accurately describe the PEO static structure factor as measured by neutron diffraction. Dynamics are assessed by comparison to neutron time of flight data, which follow self-motion of protons. Hydrogen atom motion from the EA model and carbon/oxygen atom motion from the UA model closely follow the experimental hydrogen motion, while hydrogen atoms reinserted in the UA model are too fast. The EA and UA models provide a good description of the orientation properties of C-H vectors measured by nuclear magnetic resonance experiments. Although dynamic observables in the CG model are in excellent agreement with their united atom counterparts, they cannot be compared to neutron data because the time after which the CG model is valid is greater than the neutron decay times.
Explicitly correlated composite thermochemistry of transition metal species.
Bross, David H; Hill, J Grant; Werner, H-J; Peterson, Kirk A
2013-09-07
Atomization energies were calculated using explicitly correlated coupled cluster methods with correlation consistent basis sets for a series of 19 small molecules containing 3d transition metal atoms. The atomization energies were calculated using a modified Feller-Peterson-Dixon approach in which CCSD(T) complete basis set (CBS) limits were obtained using extrapolations of aVTZ∕aVQZ CCSD(T)-F12b correlation energies, and then a series of additive contributions for relativity, core correlation, higher order correlation, and zero-point vibrations were included. The frozen-core CBS limits calculated with F12 methods closely matched the more computational expensive conventional awCVQZ∕awCV5Z CBS extrapolations, with a mean unsigned deviation of just 0.1 kcal∕mol. In particular, the CCSD(T∗)-F12b∕aVDZ and aVTZ atomization energies were more accurate on average than the conventional CCSD(T)∕aVQZ and aV5Z results, respectively. In several cases the effects of higher order correlation beyond CCSD(T), as judged by CCSDT and CCSDT(Q)Λ calculations, were greater than 1 kcal∕mol, reaching 4.5 kcal∕mol for CrO3. For the 16 molecules of this study with experimental uncertainties of ∼3.5 kcal∕mol or less, the final composite heats of formation have a mean unsigned deviation (MUD) from experiment of just 1.3 kcal∕mol, which is slightly smaller than the average of the experimental uncertainties, 1.8 kcal∕mol. The root mean square deviation (RMS) is only slightly larger at 1.7 kcal∕mol. Without the contributions due to higher order correlation effects, the MUD and RMS rise to 2.1 and 2.8 kcal∕mol, respectively. To facilitate the F12 calculations, new (aug-)cc-pVnZ∕MP2Fit (n = Q, 5) and (aug-)cc-pwCVTZ∕MP2Fit auxiliary basis sets were also developed for the transition metal atoms.
Explicitly correlated composite thermochemistry of transition metal species
NASA Astrophysics Data System (ADS)
Bross, David H.; Hill, J. Grant; Werner, H.-J.; Peterson, Kirk A.
2013-09-01
Atomization energies were calculated using explicitly correlated coupled cluster methods with correlation consistent basis sets for a series of 19 small molecules containing 3d transition metal atoms. The atomization energies were calculated using a modified Feller-Peterson-Dixon approach in which CCSD(T) complete basis set (CBS) limits were obtained using extrapolations of aVTZ/aVQZ CCSD(T)-F12b correlation energies, and then a series of additive contributions for relativity, core correlation, higher order correlation, and zero-point vibrations were included. The frozen-core CBS limits calculated with F12 methods closely matched the more computational expensive conventional awCVQZ/awCV5Z CBS extrapolations, with a mean unsigned deviation of just 0.1 kcal/mol. In particular, the CCSD(T*)-F12b/aVDZ and aVTZ atomization energies were more accurate on average than the conventional CCSD(T)/aVQZ and aV5Z results, respectively. In several cases the effects of higher order correlation beyond CCSD(T), as judged by CCSDT and CCSDT(Q)Λ calculations, were greater than 1 kcal/mol, reaching 4.5 kcal/mol for CrO3. For the 16 molecules of this study with experimental uncertainties of ˜3.5 kcal/mol or less, the final composite heats of formation have a mean unsigned deviation (MUD) from experiment of just 1.3 kcal/mol, which is slightly smaller than the average of the experimental uncertainties, 1.8 kcal/mol. The root mean square deviation (RMS) is only slightly larger at 1.7 kcal/mol. Without the contributions due to higher order correlation effects, the MUD and RMS rise to 2.1 and 2.8 kcal/mol, respectively. To facilitate the F12 calculations, new (aug-)cc-pVnZ/MP2Fit (n = Q, 5) and (aug-)cc-pwCVTZ/MP2Fit auxiliary basis sets were also developed for the transition metal atoms.
Magnetic impedance biosensor: A review.
Wang, Tao; Zhou, Yong; Lei, Chong; Luo, Jun; Xie, Shaorong; Pu, Huayan
2017-04-15
Though the magnetoimpedance effect was discovered two decades ago, the biomedical applications of the magnetoimpedance sensor are still in their infancy. In this review, the authors summarized the magnetoimpedance effect in soft ferromagnetic wires, ribbons and thin films for biosensing applications. Recent progress and achievements of the magnetoimpedance-based biosensing applications including the detection of magnetic Ferrofluid, magnetic beads, magnetic nanoparticles, magnetically labeled bioanalytes and biomagnetic fields of living systems were reviewed. The modification effect of the biochemical liquids, agglomeration effect of the magnetic particles, and the effect of the stray magnetic field on magnetoimpedance were investigated in this review. Some constructive strategies were proposed for design of the high-performance magnetoimpedance biosensor, for quantitative and ultrasensitive detection of magnetically labeled biomolecules. The theoretical and experimental results suggest that the magnetoimpedance sensors are particularly suitable for highly sensitive detection of low-concentration biomolecules, and might be used for early diagnosis and screening of cancers.
Explicit polarization: a quantum mechanical framework for developing next generation force fields.
Gao, Jiali; Truhlar, Donald G; Wang, Yingjie; Mazack, Michael J M; Löffler, Patrick; Provorse, Makenzie R; Rehak, Pavel
2014-09-16
Conspectus Molecular mechanical force fields have been successfully used to model condensed-phase and biological systems for a half century. By means of careful parametrization, such classical force fields can be used to provide useful interpretations of experimental findings and predictions of certain properties. Yet, there is a need to further improve computational accuracy for the quantitative prediction of biomolecular interactions and to model properties that depend on the wave functions and not just the energy terms. A new strategy called explicit polarization (X-Pol) has been developed to construct the potential energy surface and wave functions for macromolecular and liquid-phase simulations on the basis of quantum mechanics rather than only using quantum mechanical results to fit analytic force fields. In this spirit, this approach is called a quantum mechanical force field (QMFF). X-Pol is a general fragment method for electronic structure calculations based on the partition of a condensed-phase or macromolecular system into subsystems ("fragments") to achieve computational efficiency. Here, intrafragment energy and the mutual electronic polarization of interfragment interactions are treated explicitly using quantum mechanics. X-Pol can be used as a general, multilevel electronic structure model for macromolecular systems, and it can also serve as a new-generation force field. As a quantum chemical model, a variational many-body (VMB) expansion approach is used to systematically improve interfragment interactions, including exchange repulsion, charge delocalization, dispersion, and other correlation energies. As a quantum mechanical force field, these energy terms are approximated by empirical functions in the spirit of conventional molecular mechanics. This Account first reviews the formulation of X-Pol, in the full variationally correct version, in the faster embedded version, and with systematic many-body improvements. We discuss illustrative examples
Stack Whitney, Kaitlin; Meehan, Timothy D; Kucharik, Christopher J; Zhu, Jun; Townsend, Philip A; Hamilton, Krista; Gratton, Claudio
2016-12-01
Increases in natural or noncrop habitat surrounding agricultural fields have been shown to be correlated with declines in insect crop pests. However, these patterns are highly variable across studies suggesting other important factors, such as abiotic drivers, which are rarely included in landscape models, may also contribute to variability in insect population abundance. The objective of this study was to explicitly account for the contribution of temperature and precipitation, in addition to landscape composition, on the abundance of a widespread insect crop pest, the soybean aphid (Aphis glycines Matsumura), in Wisconsin soybean fields. We hypothesized that higher soybean aphid abundance would be associated with higher heat accumulation (e.g., growing degree days) and increasing noncrop habitat in the surrounding landscape, due to the presence of the overwintering primary hosts of soybean aphid. To evaluate these hypotheses, we used an ecoinformatics approach that relied on a large dataset collected across Wisconsin over a 9-year period (2003-2011), for an average of 235 sites per year (n = 2,110 fields total). We determined surrounding landscape composition (1.5-km radius) using publicly available satellite-derived land cover imagery and interpolated daily temperature and precipitation information from the National Weather Service COOP weather station network. We constructed linear mixed models for soybean aphid abundance based on abiotic and landscape explanatory variables and applied model averaging for prediction using an information theoretic framework. Over this broad spatial and temporal extent in Wisconsin, we found that variation in growing season precipitation was positively related to soybean aphid abundance, while higher precipitation during the nongrowing season had a negative effect on aphid populations. Additionally, we found that aphid populations were higher in areas with proportionally more forest but were lower in areas where minor crops
Explicit Polarization: A Quantum Mechanical Framework for Developing Next Generation Force Fields
2015-01-01
Conspectus Molecular mechanical force fields have been successfully used to model condensed-phase and biological systems for a half century. By means of careful parametrization, such classical force fields can be used to provide useful interpretations of experimental findings and predictions of certain properties. Yet, there is a need to further improve computational accuracy for the quantitative prediction of biomolecular interactions and to model properties that depend on the wave functions and not just the energy terms. A new strategy called explicit polarization (X-Pol) has been developed to construct the potential energy surface and wave functions for macromolecular and liquid-phase simulations on the basis of quantum mechanics rather than only using quantum mechanical results to fit analytic force fields. In this spirit, this approach is called a quantum mechanical force field (QMFF). X-Pol is a general fragment method for electronic structure calculations based on the partition of a condensed-phase or macromolecular system into subsystems (“fragments”) to achieve computational efficiency. Here, intrafragment energy and the mutual electronic polarization of interfragment interactions are treated explicitly using quantum mechanics. X-Pol can be used as a general, multilevel electronic structure model for macromolecular systems, and it can also serve as a new-generation force field. As a quantum chemical model, a variational many-body (VMB) expansion approach is used to systematically improve interfragment interactions, including exchange repulsion, charge delocalization, dispersion, and other correlation energies. As a quantum mechanical force field, these energy terms are approximated by empirical functions in the spirit of conventional molecular mechanics. This Account first reviews the formulation of X-Pol, in the full variationally correct version, in the faster embedded version, and with systematic many-body improvements. We discuss illustrative
The magnetic field of a permanent hollow cylindrical magnet
NASA Astrophysics Data System (ADS)
Reich, Felix A.; Stahn, Oliver; Müller, Wolfgang H.
2016-09-01
Based on the rational version of M AXWELL's equations according to T RUESDELL and T OUPIN or KOVETZ, cf. (Kovetz in Electromagnetic theory, Oxford University Press, Oxford, 2000; Truesdell and Toupin in Handbuch der Physik, Bd. III/1, Springer, Berlin, pp 226-793; appendix, pp 794-858, 2000), we present, for stationary processes, a closed-form solution for the magnetic flux density of a hollow cylindrical magnet. Its magnetization is constant in axial direction. We consider M AXWELL's equations in regular and singular points that are obtained by rational electrodynamics, adapted to stationary processes. The magnetic flux density is calculated analytically by means of a vector potential. We obtain a solution in terms of complete elliptic integrals. Therefore, numerical evaluation can be performed in a computationally efficient manner. The solution is written in dimensionless form and can easily be applied to cylinders of arbitrary shape. The relation between the magnetic flux density and the magnetic field is linear, and an explicit relation for the field is presented. With a slight modification the result can be used to obtain the field of a solid cylindrical magnet. The mathematical structure of the solution and, in particular, singularities are discussed.
A Connectionist Extension to Kintsch's Construction--Integration Model
ERIC Educational Resources Information Center
Sanjose, Vicente; Vidal-Abarca, Eduardo; Padilla, Olga M.
2006-01-01
This article proposes an extension to Kintsch's Construction-Integration (CI) model of text comprehension, which changes its mathematical implementation and emphasizes the connectionist features of the model. Specifically, the extension proposed here (a) simulates the learning process in a connectionist manner by making explicit changes in the…
Tunnel construction for a desertron
Hinterberger, H.; Huson, F.R.
1983-03-27
The tunnel in this model of construction is 3-1/2 feet wide by 5 feet high. It is assumed that the tunnel contains a rail system and guidance system for: (1) An enclosed car used for transport of 2 people and some tools. (2) A magnet mover. This robot could pick up a magnet and transport it at about 10 miles per hour. (3) An alignment robot. The alignment robot would intercept E.M. waves (microwaves, lasers) to determine its position in the tunnel. Then workers could come along inside the tunnel hoop and nail it together and to the floor. The trench would then be back-filled with a 1 foot berm on top. A rail system would be installed and a support stand for the magnet.
NASA Astrophysics Data System (ADS)
Hayat, Tasawar; Ijaz Khan, Muhammad; Imtiaz, Maria; Alsaedi, Ahmed; Waqas, Muhammad
2016-10-01
A simple model of chemical reactions for two dimensional ferrofluid flows is constructed. The impact of magnetic dipole and mixed convection is further analyzed. Flow is caused by linear stretching of the sheet. Similarity transformation is adopted to convert the partial differential equations into ordinary differential equations and then solved by Euler's explicit method. The characteristics of sundry parameters on the velocity, temperature, and concentration fields are graphically elaborated. It is noted that the impact of magneto-thermomechanical interaction is to slow down the fluid motion. The skin friction coefficient enhances and affects the rate of heat transfer. For higher values of ferrohydrodynamics, the interaction velocity shows decreasing behavior. Further the Prandtl number on temperature has opposite behavior when compared with thermal radiation and ferrohydrodynamics interaction.
Superconducting combined function magnets
Hahn, H.; Fernow, R.C.
1983-01-01
Superconducting accelerators and storage rings, presently under construction or in the design phase, are based on separate dipole and quadrupole magnets. It is here suggested that a hybrid lattice configuration consisting of dipoles and combined function gradient magnets would: (1) reduce the number of magnet units and their total cost; and (2) increase the filling factor and thus the energy at a given field. Coil cross sections are presented for the example of the Brookhaven Colliding Beam Accelerator. An asymmetric two-layer cable gradient magnet would have transfer functions of 10.42 G/A and 0.628 G cm/sup -1//A versus 15.77 G/A and 2.03 G cm/sup -1//A of the present separate dipoles and quadrupoles.
Construction of energy-momentum tensor of gravitation
NASA Astrophysics Data System (ADS)
Bamba, Kazuharu; Shimizu, Katsutaro
2016-10-01
We construct the gravitational energy-momentum tensor in general relativity through the Noether theorem. In particular, we explicitly demonstrate that the constructed quantity can vary as a tensor under the general coordinate transformation. Furthermore, we verify that the energy-momentum conservation is satisfied because one of the two indices of the energy-momentum tensor should be in the local Lorentz frame. It is also shown that the gravitational energy and the matter one cancel out in certain space-times.
Martian Magnets Under the Microscope
NASA Technical Reports Server (NTRS)
2004-01-01
NASA's Mars Exploration Rover Spirit acquired this microscopic imager view of its capture magnet on sol 92 (April 6, 2004). Both Spirit and the Mars Exploration Rover Opportunity are equipped with a number of magnets. The capture magnet, as seen here, has a stronger charge than its sidekick, the filter magnet. The lower-powered filter magnet captures only the most magnetic airborne dust with the strongest charges, while the capture magnet picks up all magnetic airborne dust.
The magnets' primary purpose is to collect the martian magnetic dust so that scientists can analyze it with the rovers' Moessbauer spectrometers. While there is plenty of dust on the surface of Mars, it is difficult to confirm where it came from, and when it was last airborne. Because scientists are interested in learning about the properties of the dust in the atmosphere, they devised this dust-collection experiment.
The capture magnet is about 4.5 centimeters (1.8 inches) in diameter and is constructed with a central cylinder and three rings, each with alternating orientations of magnetization. Scientists have been monitoring the continual accumulation of dust since the beginning of the mission with panoramic camera and microscopic imager images. They had to wait until enough dust accumulated before they could get a Moessbauer spectrometer analysis. The results of that analysis, performed on sol 92, have not been sent back to Earth yet.
ERIC Educational Resources Information Center
Glock, Sabine; Beverborg, Arnoud Oude Groote; Müller, Barbara C. N.
2016-01-01
Obese children experience disadvantages in school and discrimination from their teachers. Teachers' implicit and explicit attitudes have been identified as contributing to these disadvantages. Drawing on dual process models, we investigated the nature of pre-service teachers' implicit and explicit attitudes, their motivation to respond without…
Steele, Vaughn R.; Staley, Cameron; Sabatinelli, Dean
2015-01-01
Risky sexual behaviors typically occur when a person is sexually motivated by potent, sexual reward cues. Yet, individual differences in sensitivity to sexual cues have not been examined with respect to sexual risk behaviors. A greater responsiveness to sexual cues might provide greater motivation for a person to act sexually; a lower responsiveness to sexual cues might lead a person to seek more intense, novel, possibly risky, sexual acts. In this study, event-related potentials were recorded in 64 men and women while they viewed a series of emotional, including explicit sexual, photographs. The motivational salience of the sexual cues was varied by including more and less explicit sexual images. Indeed, the more explicit sexual stimuli resulted in enhanced late positive potentials (LPP) relative to the less explicit sexual images. Participants with fewer sexual intercourse partners in the last year had reduced LPP amplitude to the less explicit sexual images than the more explicit sexual images, whereas participants with more partners responded similarly to the more and less explicit sexual images. This pattern of results is consistent with a greater responsivity model. Those who engage in more sexual behaviors consistent with risk are also more responsive to less explicit sexual cues. PMID:24526189
The Neglected Combination: A Case for Explicit-Inductive Instruction in Teaching Pragmatics in ESL
ERIC Educational Resources Information Center
Glaser, Karen
2013-01-01
A substantial part of interlanguage pragmatics (ILP) research has contrasted explicit and implicit teaching designs, generally finding that explicit approaches--those featuring metapragmatic rule provision--are more effective than their implicit counterparts, which are characterized by the absence of metapragmatic information. A second dichotomy…
Aptitude-Treatment Interaction Effects on Explicit Rule Learning: A Latent Growth Curve Analysis
ERIC Educational Resources Information Center
Hwu, Fenfang; Pan, Wei; Sun, Shuyan
2014-01-01
Finding the match between individuals and educational treatments is the aim of both educators and the aptitude-treatment interaction research paradigm. Using the latent growth curve analysis, the present study investigates the interaction between the type of explicit instructional approaches (deductive vs. explicit-inductive) and the level of…
Dissociation between implicit and explicit expectancies of cannabis use in adolescence.
Schmits, Emilie; Maurage, Pierre; Thirion, Romain; Quertemont, Etienne
2015-12-30
Cannabis is one of the most commonly drugs used by teenagers. Expectancies about its effects play a crucial role in cannabis consumption. Various tools have been used to assess expectancies, mainly self-report questionnaires measuring explicit expectancies, but implicit measures based on experimental tasks have also been developed, measuring implicit expectancies. The aim of this study was to simultaneously assess implicit/explicit expectancies related to cannabis among adolescent users and non-users. 130 teenagers attending school (55 girls) were enrolled (Age: M=16.40 years); 43.84% had never used cannabis ("non-users") and 56.16% had used cannabis ("users"). They completed self-report questionnaires evaluating cannabis use, cannabis-related problems, effect expectancies (explicit expectancies), alcohol use, social and trait anxiety, depression, as well as three Implicit Association Tests (IAT) assessing implicit expectancies. Adolescents manifested more implicit affective associations (relaxation, excitation, negative) than neutral ones regarding cannabis. These were not related to explicit expectancies. Cannabis users reported more implicit relaxation expectancies and less negative explicit expectancies than non-users. The frequency of use and related problems were positively associated with the explicit expectancies regarding relaxation and enhancement, and were negatively associated with negative explicit expectancies and negative implicit expectancies. Findings indicate that implicit and explicit expectancies play different roles in cannabis use by adolescents. The implications for experimentation and prevention are discussed.
ERIC Educational Resources Information Center
Cil, Emine
2014-01-01
In this study, fifteen pre-service early childhood teachers' views of nature of science (NOS) were analysed. The student teachers took a course where NOS was taught via explicit reflective approach. The explicit reflective approach advocates that goal of improving students' NOS views should be planned for instead of being anticipated as…
Implicit and Explicit Memory for Affective Passages in Temporal Lobectomy Patients
ERIC Educational Resources Information Center
Burton, Leslie A.; Rabin, Laura; Vardy, Susan Bernstein; Frohlich, Jonathan; Porter, Gwinne Wyatt; Dimitri, Diana; Cofer, Lucas; Labar, Douglas
2008-01-01
Eighteen temporal lobectomy patients (9 left, LTL; 9 right, RTL) were administered four verbal tasks, an Affective Implicit Task, a Neutral Implicit Task, an Affective Explicit Task, and a Neutral Explicit Task. For the Affective and Neutral Implicit Tasks, participants were timed while reading aloud passages with affective or neutral content,…
Implicit and Explicit Knowledge of Linear and Exponential Growth in 5- and 9-Year-Olds
ERIC Educational Resources Information Center
Ebersbach, Mirjam; Resing, Wilma C. M.
2008-01-01
The present study examined children's implicit and explicit knowledge of linear and non-linear processes. Five- and nine-year-olds (N = 60) were asked to forecast linear and exponential growth by providing the corresponding number of beads. Implicit knowledge was assessed via the magnitudes of the forecasts; explicit knowledge was investigated…
ERIC Educational Resources Information Center
Jurkovic, Violeta
2010-01-01
The present article reports on the findings of a study that explored the effect of explicit language learning strategy instruction on the development of English as a foreign language within a higher education setting in mixed language ability groups. The research results indicate that explicit language learning strategy instruction that aimed at…
Implicit and Explicit Memory Performance in Children with Attention Deficit/Hyperactivity Disorder
ERIC Educational Resources Information Center
Aloisi, Bruno A.; McKone, Elinor; Heubeck, Bernd G.
2004-01-01
The present investigation examined implicit and explicit memory in 20 children diagnosed with attention deficit/hyperactivity disorder (AD/HD) and 20 matched controls. Consistent with previous research, children with AD/HD performed more poorly than controls on an explicit test of long-term memory for pictures. New results were that (a) there was…
At the Interface: Dynamic Interactions of Explicit and Implicit Language Knowledge
ERIC Educational Resources Information Center
Ellis, Nick C.
2005-01-01
This paper considers how implicit and explicit knowledge are dissociable but cooperative. It reviews various psychological and neurobiological processes by which explicit knowledge of form-meaning associations impacts upon implicit language learning. The interface is dynamic: It happens transiently during conscious processing, but the influence…
Moderators of implicit and explicit drinking identity in a large US adult sample.
Lindgren, Kristen P; Gasser, Melissa L; Werntz, Alexandra; Namaky, Nauder; Baldwin, Scott A; Teachman, Bethany A
2016-09-01
Drinking identity (viewing oneself as a drinker) is a potential risk factor for problematic drinking in US undergraduate samples. Whether that risk extends to a broader, more general US sample is unknown. Additionally, there are critical, unanswered questions with respect to moderators of the drinking identity-problematic drinking relationship; an important issue for designing prevention efforts. Study aims were to assess the unique associations and interactive effects of implicit and explicit measures of drinking identity on problematic drinking, and to evaluate age and sex as potential moderators of the drinking identity-problematic drinking relationship. A sample of 11,320 adults aged 18-98 completed measures of implicit and explicit drinking identity and problematic drinking (the Alcohol Use Disorder Identification Test; AUDIT). Implicit and explicit drinking identity had positive, significant associations with AUDIT scores, as expected. Moderation analyses indicated small, but significant, interactions. There was an implicit by explicit identity interaction consistent with a synergistic effect: lower implicit and explicit identity was linked to a greater probability of being a non-drinker. Age moderated explicit but not implicit identity: lower drinking identity appeared to be more protective for younger individuals. Sex moderated implicit but not explicit identity: a weaker positive association with implicit identity and AUDIT scores was observed among men, potentially reflecting stigma against women's drinking. Findings suggest that drinking identity's potential as a risk factor for problematic drinking extends to a more general US sample and that both implicit and explicit identity should be targeted in prevention efforts.
Shifting from Implicit to Explicit Knowledge: Different Roles of Early- and Late-Night Sleep
ERIC Educational Resources Information Center
Yordanova, Juliana; Kolev, Vasil; Verleger, Rolf; Bataghva, Zhamak; Born, Jan; Wagner, Ullrich
2008-01-01
Sleep has been shown to promote the generation of explicit knowledge as indicated by the gain of insight into previously unrecognized task regularities. Here, we explored whether this generation of explicit knowledge depends on pre-sleep implicit knowledge, and specified the differential roles of slow-wave sleep (SWS) vs. rapid eye movement (REM)…