The rhomboidal symmetric four-body problem
NASA Astrophysics Data System (ADS)
Waldvogel, Jörg
2012-05-01
We consider the planar symmetric four-body problem with two equal masses m 1 = m 3 > 0 at positions (± x 1( t), 0) and two equal masses m 2 = m 4 > 0 at positions (0, ± x 2( t)) at all times t, referred to as the rhomboidal symmetric four-body problem. Owing to the simplicity of the equations of motion this problem is well suited to study regularization of the binary collisions, periodic solutions, chaotic motion, as well as the four-body collision and escape manifolds. Furthermore, resonance phenomena between the two interacting rectilinear binaries play an important role.
The trapezoidal collinear four-body problem
NASA Astrophysics Data System (ADS)
Alvarez-Ramírez, Martha; Medina, Mario; Vidal, Claudio
2015-07-01
This paper consider the trapezoidal collinear four-body problem as a model for binary-binary gravitational interaction in star clusters. It has two degrees of freedom, it also is a sub-problem of the trapezoidal four-body problem that has three degrees of freedom. We prove that all its singularities in the trapezoidal four-body problem are due to collision and give some results regarding escapes to infinity. In order to give a description of the orbits suffering collisions between two bodies while the other two escape to infinity with zero radial velocity (parabolic orbits), we make use of the McGehee's techniques to blow-up-regularize the singularities due to collision and infinity.
Celestial mechanics: Fresh solutions to the four-body problem
NASA Astrophysics Data System (ADS)
Hamilton, Douglas P.
2016-05-01
Describing the motion of three or more bodies under the influence of gravity is one of the toughest problems in astronomy. The report of solutions to a large subclass of the four-body problem is truly remarkable.
Periodic orbits in the restricted four-body problem
NASA Astrophysics Data System (ADS)
Howell, K. C.; Spencer, D. B.
1985-10-01
One solution to the restricted three-body problem is that of three-dimensional, periodic halo orbits. These orbits emanate from the three collinear libration points and exist at all possible mass ratios of the primaries, with infinite possible trajectories. Their existence motivated this study of the effect of an additional gravitational influence on the motion. The approach is to seek a solution in the restricted four-body problem using halo solutions as an initial approximation. The method first solves for periodic, coplanar motion of the three primaries under their mutual gravitational attractions and represents them as trigonometric series. Then, under the modified gravity force model, a three-dimensional solution is obtained in the problem of four bodies, periodic with respect to the synodic system of the three primaries. The additional primary remains relatively far removed and acts as a perturbing influence on the original motion. Some shape and stability characteristics are presented for three such solutions.
Sitnikov restricted four-body problem with radiation pressure
NASA Astrophysics Data System (ADS)
Suraj, Md Sanam; Hassan, M. R.
2014-02-01
An analytical study of the elliptic Sitnikov restricted four-body problem when all the primaries as source of same radiation pressure is presented. We find a solution, which is valid for small bounded oscillations in case of moderate eccentricity of the primary. We have linearized the equation of motion to obtain the Hill's type equation. Using the Courant and Snyder transformation, Hill's equation transformed into harmonic oscillator type equation. We have used the Lindstedt-Poincare perturbation method and again we have applied the Courant and Snyder transformation to obtain the final result.
On the Symmetric Collinear Four-Body Problem
NASA Astrophysics Data System (ADS)
Sekiguchi, Masayoshi; Tanikawa, Kiyotaka
2004-02-01
The global geometry of the phase structure in a special case of the general Newtonian four-body problem was studied both analytically and numerically in the case of negative energy. Our method consists of blow-up of total collision by McGehee's coordinates. and representation of orbits by symbol sequences. The analytical study for arbitrary masses clarifies the macroscopic behavior in phase space: escape motion, vortical motion around vertical lines along which the escape motion occurs, and vertical convective flow. We numerically examined a distribution of the symbol sequences on a surface of section in the case of equal masses. The result has clarified that there never exist orbits whose symbol sequences contain special words: un-realizable words. On the other hand, the existence of oscillatory motions are shown under a reasonable assumption. We semi-analytically obtained the initial conditions leading to escape using escape criteria established in the present study. Additionally, we established a way to find the fastest capture-escape orbits, the ejection-collision orbits besides the homothetic solution, the capture-collision orbits, and the ejection-escape orbits. Moreover, quasi-periodic orbits containing a Schubart-like orbit, and unstable periodic orbits were found. The result displays a similarity between the symmetric collinear four-body problem and the collinear three-body problem.
Regularization of the restricted problem of four bodies.
NASA Technical Reports Server (NTRS)
Giacaglia, G. E. O.
1967-01-01
Regularization of restricted three-body problem extended to case where three primaries of any mass revolve in circular orbits around common center of mass and fourth body of infinitesimal mass moves in their field
3D periodic orbits in the restricted four body problem
NASA Astrophysics Data System (ADS)
Baltagiannis, A.; Papadakis, K.
2013-09-01
One big body (Sun) of mass m1 and two other small bodies of masses m2 and m3 correspondingly, move in circular orbits keeping an equilateral triangle configuration, about the center of mass of the system fixed at the origin of the coordinate system. A massless particle is moving under the Newtonian gravitational attraction of the primaries and does not affect the motion of the three bodies. Using the vertical-critical orbits of planar families of symmetric periodic orbits as starting points, we determine and present in this paper, families of three-dimensional periodic solutions of the problem. Characteristic curves of the 3D-families which emanate from the plane are presented. The stability of every three-dimensional periodic orbit which numerically calculated is also studied.
Hill stability of the satellites in coplanar four-body problem
NASA Astrophysics Data System (ADS)
Gong, Shengping; Liu, Chao
2016-10-01
We consider a four-body system, where three bodies, constituting a subsystem, orbit around a larger body. This paper is devoted to study the Hill stability of the subsystem using a coplanar four-body problem. Starting from the equation of zero-velocity surface for the general coplanar four-body problem, we derive two criteria of Hill stability, one of which is similar to the criterion of Hill stability in the three-body problem. These criteria are used to judge the Hill stability of the Sun-Jupiter-Ganymede-Callisto system.
NASA Astrophysics Data System (ADS)
Qi, Rui; Huang, Biao
2016-01-01
Transport mechanism is critical for understanding natural phenomena in the solar system and is beneficial to space mission design. In this study, transport mechanism in the bicircular four-body problem is numerically explored by using Lagrangian coherent structure (LCS), a tool widely used for identifying transport barriers in fluid flow. First, equations of motion of the bicircular problem are derived and five topology configurations of forbidden region are presented. Then, definition and computational method of LCS are introduced. Finally, properties of LCS which are useful for revealing transport mechanism in the four-body problem are numerically investigated.
Periodic orbits in the restricted four-body problem with two equal masses
NASA Astrophysics Data System (ADS)
Burgos-García, Jaime; Delgado, Joaquín
2013-06-01
The restricted (equilateral) four-body problem consists of three bodies of masses m 1, m 2 and m 3 (called primaries) lying in a Lagrangian configuration of the three-body problem i.e., they remain fixed at the apices of an equilateral triangle in a rotating coordinate system. A massless fourth body moves under the Newtonian gravitation law due to the three primaries; as in the restricted three-body problem (R3BP), the fourth mass does not affect the motion of the three primaries. In this paper we explore symmetric periodic orbits of the restricted four-body problem (R4BP) for the case of two equal masses where they satisfy approximately the Routh's critical value. We will classify them in nine families of periodic orbits. We offer an exhaustive study of each family and the stability of each of them.
Families of periodic orbits in the planar Hill's four-body problem
NASA Astrophysics Data System (ADS)
Burgos-García, Jaime
2016-11-01
In this work we perform numerical explorations of some families of planar periodic orbits in the Hill approximation of the restricted four-body problem. This approximation is obtained by performing a symplectic scaling which sends the two massive bodies to infinity, by the means of expanding the potential as a power series depending on the mass of the smallest primary, and taking the limit as this mass tends to zero. The limiting Hamiltonian depends only on the relative mass of the second smallest primary. The resulting dynamics shares similarities with both the restricted three-body problem and the restricted four-body problem. We focus on certain families of symmetric periodic orbits of the infinitesimal particle, for some values of the mass parameter. We explore the evolution of these families as the Jacobi constant, or, equivalently, the energy, is varied continuously, and provide details on the horizontal and vertical stability of each family.
Spacecraft trajectory design in the context of a coherent restricted four-body problem
NASA Astrophysics Data System (ADS)
Guzman, Jose Javier
Consider the design of transfer trajectories to the vicinity of the Sun-Earth collinear libration points. First, note that the equilibrium points actually exist only in the circular restricted three-body problem (CROP). Second, conic solutions are generally not useful (even as initial guesses). Therefore, for libration point missions, most of the qualitative analysis must be accomplished from the perspective of a model with, at least, three bodies. Unfortunately, in some cases, the qualitative behavior that is apparent in the CR3BP might be completely lost due to lunar perturbations. Alternatively, a transfer strategy to exploit the potential advantage of the Moon's presence through gravitational encounters is difficult to implement within the context of either the CR3BP or a model that employs ephemeris information for the Sun and Earth locations. Clearly, a formulation of the four-body problem is warranted. To maximize the four-body model as a useful component, special solutions---such as periodic and quasi-periodic trajectories in the restricted four-body problem---are initially isolated and identified. Semi-analytical approximations (for the special solutions) are obtained with the method of spectral balance and refined via differential corrections. Then, an analysis from the perspective of dynamical systems proceeds. Such an approach is employed in the Sun-Earth system to develop transfer options to L2 Lissajous trajectories; subsequent applications include NASA's Microwave Anisotropy Probe (MAP) mission.
Minesaki, Yukitaka
2015-01-01
We propose the discrete-time restricted four-body problem (d-R4BP), which approximates the orbits of the restricted four-body problem (R4BP). The d-R4BP is given as a special case of the discrete-time chain regularization of the general N-body problem published in Minesaki. Moreover, we analytically prove that the d-R4BP yields the correct orbits corresponding to the elliptic relative equilibrium solutions of the R4BP when the three primaries form an equilateral triangle at any time. Such orbits include the orbit of a relative equilibrium solution already discovered by Baltagiannis and Papadakis. Until the proof in this work, there has been no discrete analog that preserves the orbits of elliptic relative equilibrium solutions in the R4BP. For a long time interval, the d-R4BP can precisely compute some stable periodic orbits in the Sun–Jupiter–Trojan asteroid–spacecraft system that cannot necessarily be reproduced by other generic integrators.
Stability of libration points in the restricted four-body problem with variable mass
NASA Astrophysics Data System (ADS)
Mittal, Amit; Aggarwal, Rajiv; Suraj, Md. Sanam; Bisht, Virender Singh
2016-10-01
We have investigated the stability of the Lagrangian solutions for the restricted four-body problem with variable mass. It has been assumed that the three primaries with masses m1, m2 and m3 form an equilateral triangle, wherein m2=m3. According to Jeans' law (Astronomy and Cosmogony, Cambridge University Press, Cambridge, 1928), the infinitesimal body varies its mass m with time. The space-time transformations of Meshcherskii (Studies on the Mechanics of Bodies of Variable Mass, GITTL, Moscow, 1949) are used by taking the values of the parameters q=1/2, k=0, n=1. The equations of motion of the infinitesimal body with variable mass have been determined. The equations of motion of the current problem differ from the ones of the restricted four-body problem with constant mass. There exist eight libration points, out of which two are collinear with the primary m1 and the rest are non-collinear for a fixed value of parameters γ (m {at time} t/m {at initial time}, 0<γ≤1 ), α (the proportionality constant in Jeans' law (Astronomy and Cosmogony, Cambridge University Press, Cambridge, 1928), 0≤α≤2.2) and μ=0.019 (the mass parameter). All the libration points are found to be unstable. The zero velocity surfaces (ZVS) are also drawn and regions of motion are discussed.
Pseudo-heteroclinic connections between bicircular restricted four-body problems
NASA Astrophysics Data System (ADS)
Barrabés, Esther; Gómez, Gerard; Mondelo, Josep M.; Ollè, Mercé
2016-10-01
In this paper, we show a mechanism to explain transport from the outer to the inner Solar system. Such a mechanism is based on dynamical systems theory. More concretely, we consider a sequence of uncoupled bicircular restricted four-body problems -BR4BP -(involving the Sun, Jupiter, a planet and an infinitesimal mass), being the planet Neptune, Uranus and Saturn. For each BR4BP, we compute the dynamical substitutes of the collinear equilibrium points of the corresponding restricted three-body problem (Sun, planet and infinitesimal mass), which become periodic orbits. These periodic orbits are unstable, and the role that their invariant manifolds play in relation with transport from exterior planets to the inner ones is discussed.
The chaotic four-body problem in Newtonian gravity I: Identical point-particles
NASA Astrophysics Data System (ADS)
Leigh, Nathan W. C.; Stone, Nicholas C.; Geller, Aaron M.; Shara, Michael M.; Muddu, Harsha; Solano-Oropeza, Diana; Thomas, Yancey
2016-08-01
In this paper, we study the chaotic four-body problem in Newtonian gravity. Assuming point particles and total encounter energies ≤ 0, the problem has three possible outcomes. We describe each outcome as a series of discrete transformations in energy space, using the diagrams first presented in Leigh & Geller (2012; see the Appendix). Furthermore, we develop a formalism for calculating probabilities for these outcomes to occur, expressed using the density of escape configurations per unit energy, and based on the Monaghan description originally developed for the three-body problem. We compare this analytic formalism to results from a series of binary-binary encounters with identical point particles, simulated using the
Study of lunar gravity assist orbits in the restricted four-body problem
NASA Astrophysics Data System (ADS)
Qi, Yi; Xu, Shijie
2016-07-01
In this paper, the lunar gravity assist (LGA) orbits starting from the Earth are investigated in the Sun-Earth-Moon-spacecraft restricted four-body problem (RFBP). First of all, the sphere of influence of the Earth-Moon system (SOIEM) is derived. Numerical calculation displays that inside the SOIEM, the effect of the Sun on the LGA orbits is quite small, but outside the SOIEM, the Sun perturbation can remarkably influence the trend of the LGA orbit. To analyze the effect of the Sun, the RFBP outside the SOIEM is approximately replaced by a planar circular restricted three-body problem, where, in the latter case, the Sun and the Earth-Moon barycenter act as primaries. The stable manifolds associated with the libration point orbit and their Poincaré sections on the SOIEM are applied to investigating the LGA orbit. According to our research, the patched LGA orbits on the Poincaré sections can efficiently distinguish the transit LGA orbits from the non-transit LGA orbits under the RFBP. The former orbits can pass through the region around libration point away from the SOIEM, but the latter orbits will bounce back to the SOIEM. Besides, the stable transit probability is defined and analyzed. According to the variant requirement of the space mission, the results obtained can help us select the LGA orbit and the launch window.
Stability regions of equilibrium points in restricted four-body problem with oblateness effects
NASA Astrophysics Data System (ADS)
Kumari, Reena; Kushvah, Badam Singh
2014-02-01
In this paper, we extend the basic model of the restricted four-body problem introducing two bigger dominant primaries m 1 and m 2 as oblate spheroids when masses of the two primary bodies ( m 2 and m 3) are equal. The aim of this study is to investigate the use of zero velocity surfaces and the Poincaré surfaces of section to determine the possible allowed boundary regions and the stability orbit of the equilibrium points. According to different values of Jacobi constant C, we can determine boundary region where the particle can move in possible permitted zones. The stability regions of the equilibrium points expanded due to presence of oblateness coefficient and various values of C, whereas for certain range of t (100≤ t≤200), orbits form a shape of cote's spiral. For different values of oblateness parameters A 1 (0< A 1<1) and A 2 (0< A 2<1), we obtain two collinear and six non-collinear equilibrium points. The non-collinear equilibrium points are stable when the mass parameter μ lies in the interval (0.0190637,0.647603). However, basins of attraction are constructed with the help of Newton Raphson method to demonstrate the convergence as well as divergence region of the equilibrium points. The nature of basins of attraction of the equilibrium points are less effected in presence and absence of oblateness coefficients A 1 and A 2 respectively in the proposed model.
NASA Astrophysics Data System (ADS)
Arribas, M.; Abad, A.; Elipe, A.; Palacios, M.
2016-08-01
In this paper, a three dimensional case of the restricted four-body problem with radiation pressure is considered. The three primaries are supposed to be in a collinear central configuration where both masses and both radiation forces of peripheral bodies are equal. In addition to the analysis of the equilibria in the planar problem introduced in a previous paper by the authors, we present here a complete study of position and stability of the equilibrium points out of {Oxy} plane.
NASA Astrophysics Data System (ADS)
Shahbaz Ullah, M.; Hassan, M. R.
2014-09-01
In this manuscript we have established averaged equation of motion of the Sitnikov restricted three- body and four-body problem when all the primaries are point masses, by applying the Van der Pol transformation and averaging technique of J. Guckenheimer and P. Holmes (in Nonlinear Oscillations, Dynamical System Bifurcations of Vector Fields, Springer, Berlin, 1983). In addition to the resonance criterion at the 3/2 commensurability we have chosen ω=2 n/3, n=4, ω is the angular velocity of the coordinate system. Further we established the Series solution of the three-body and four-body problem in the sense of Sitnikov. Lastly the periodicities of the solutions have been examined by the Poincare section and four-body and three-body problem have been compared by different comparative graphs and surfaces.
NASA Astrophysics Data System (ADS)
Machuy, A. L.; Prado, A. F. B. A.; Stuchi, T. J.
A gravitational capture occurs when a spacecraft (or any particle with negligible mass) changes from a hyperbolic orbit with a small positive energy around a celestial body into an elliptic orbit with a small negative energy without the use of any propulsive system. The force responsible for this modification in the orbit of the spacecraft is the gravitational force of the third and the fourth bodies involved in the dynamics. In this way, those forces are used as a zero cost control, equivalent to a continuous thrust applied in the spacecraft. One of the most important applications of this property is the construction of trajectories to the Moon to minimize fuel consumption. The concept of gravitational capture is used, together with the basic ideas of the gravity-assisted maneuver and the bi-elliptic transfer orbit, to generate a trajectory that requires fuel consumption smaller than the one required by the Hohmann transfer. The objective of the present paper is to study the time required for the ballistic gravitational capture in a dynamical model that has the presence of four bodies. In particular, the Earth-Moon-Sun-Spacecraft system is considered.
Four-body trajectory optimization
NASA Technical Reports Server (NTRS)
Pu, C. L.; Edelbaum, T. N.
1973-01-01
A collection of typical three-body trajectories from the L1 libration point on the sun-earth line to the earth is presented. These trajectories in the sun-earth system are grouped into four distinct families which differ in transfer time and delta V requirements. Curves showing the variations of delta V with respect to transfer time, and typical two and three-impulse primer vector histories, are included. The development of a four-body trajectory optimization program to compute fuel optimal trajectories between the earth and a point in the sun-earth-moon system are also discussed. Methods for generating fuel optimal two-impulse trajectories which originate at the earth or a point in space, and fuel optimal three-impulse trajectories between two points in space, are presented. A brief qualitative comparison of these methods is given. An example of a four-body two-impulse transfer from the Li libration point to the earth is included.
Four-body trajectory optimization
NASA Technical Reports Server (NTRS)
Pu, C. L.; Edelbaum, T. N.
1974-01-01
A comprehensive optimization program has been developed for computing fuel-optimal trajectories between the earth and a point in the sun-earth-moon system. It presents methods for generating fuel optimal two-impulse trajectories which may originate at the earth or a point in space and fuel optimal three-impulse trajectories between two points in space. The extrapolation of the state vector and the computation of the state transition matrix are accomplished by the Stumpff-Weiss method. The cost and constraint gradients are computed analytically in terms of the terminal state and the state transition matrix. The 4-body Lambert problem is solved by using the Newton-Raphson method. An accelerated gradient projection method is used to optimize a 2-impulse trajectory with terminal constraint. The Davidon's Variance Method is used both in the accelerated gradient projection method and the outer loop of a 3-impulse trajectory optimization problem.
Theoretical Fully Differential Cross Sections for Four-Body Processes
NASA Astrophysics Data System (ADS)
Harris, A. L.; Peacher, J. L.; Schulz, M.; Madison, D. H.
2008-04-01
Atomic collisions present a valuable opportunity to study the few body problem. Advances on the theoretical side now allow for an essentially exact numerical calculation of one of the simplest the few-body problems - the three-body problem. However, study of the four-body problem is still in its infancy, and the agreement between experiment and theory for kinematically complete experiments is far from satisfactory. The simplest four-body problem is a charged particle collision with helium in which both atomic electrons change state. Two theoretical models will be discussed for several possible outcomes of this type of collision. The first Born approximation (FBA) treats the projectile as a plane wave, and ignores the post collision Coulomb interaction between the two final state continuum electrons. The more sophisticated four-body distorted wave (4DW) model treats all continuum particles as distorted waves and explicitly includes the post collision Coulomb interaction between the two outgoing electrons. Fully differential cross sections calculated using the FBA and 4DW models will be compared to absolute experimental results, as well as other theories.
Four-body correlations in nuclei.
Sambataro, M; Sandulescu, N
2015-09-11
Low-energy spectra of 4n nuclei are described with high accuracy in terms of four-body correlated structures ("quartets"). The states of all N≥Z nuclei belonging to the A=24 isobaric chain are represented as a superposition of two-quartet states, with quartets being characterized by isospin T and angular momentum J. These quartets are assumed to be those describing the lowest states in ^{20}Ne (T_{z}=0), ^{20}F (T_{z}=1), and ^{20}O (T_{z}=2). We find that the spectrum of the self-conjugate nucleus ^{24}Mg can be well reproduced in terms of T=0 quartets only and that, among these, the J=0 quartet plays by far the leading role in the structure of the ground state. The same conclusion is drawn in the case of the three-quartet N=Z nucleus ^{28}Si. As an application of the quartet formalism to nuclei not confined to the sd shell, we provide a description of the low-lying spectrum of the proton-rich ^{92}Pd. The results achieved indicate that, in 4n nuclei, four-body degrees of freedom are more important and more general than usually expected. PMID:26406824
Evidence for universal four-body states tied to an Efimov trimer.
Ferlaino, F; Knoop, S; Berninger, M; Harm, W; D'Incao, J P; Nägerl, H-C; Grimm, R
2009-04-10
We report on the measurement of four-body recombination rate coefficients in an atomic gas. Our results obtained with an ultracold sample of cesium atoms at negative scattering lengths show a resonant enhancement of losses and provide strong evidence for the existence of a pair of four-body states, which is strictly connected to Efimov trimers via universal relations. Our findings confirm recent theoretical predictions and demonstrate the enrichment of the Efimov scenario when a fourth particle is added to the generic three-body problem. PMID:19392415
Experimental Droplet Impingement on Four Bodies of Revolution
NASA Technical Reports Server (NTRS)
Lewis, James P.; Ruggeri, Robert S.
1957-01-01
The rate and. area of cloud droplet impingement on four bodies of revolution were obtained experimentally in the NACA Lewis icing tunnel with a dye-tracer technique. The study included spheres, ellipsoidal forebodies of fineness ratios of 2.5 and 3.0, and a conical forebody of 300 included angle and covered a range of angles of attack from 0? to 60 and rotational speeds up to 1200 rpm. The data were obtained at an airspeed of 157 knots and are correlated by dimensionless impingement parameters. In general, the experimental data show that the local and total impingement rates and impingement limits of bodies of revolution are primarily functions of the modified inertia parameters, the body shape, and fineness ratio. Both the local impingement rate and impingement limits depend upon the angle of attack. Rotation of the bodies had a negligible effect on the impingement characteristics except for an averaging effect at angle of attack. For comparable diameters the bluffer bodies had the largest total impingement efficiency, but the finer and sharper bodies had the largest values of maximum local impingement efficiency and, in most cases, the largest limits of impingement. In most cases, the impingement characteristics were less than those calculated from theoretical trajectories; in general, however, fairly good agreement was obtained between the experimental and theoretical impingement characteristics.
Comparison Transfer Orbits Between the Restricted Three and Four Body Systems
NASA Astrophysics Data System (ADS)
Correa, A. A.; Prado, A. F.; Beauge, C.; Stuchi, T. J.
The two dynamical systems involved in this research are the restricted three-body problem and the quasi bicircular problem. The first one studies the motion of one massless body in the potential field of the others two massive bodies revolving in circular orbit around the centre of mass. The restriction of this model lies on the fact that the neglected body moves without disturbing the motion of primaries bodies. This model can be extended to application in the system of more bodies, in fact, this is the simplest n-problem formulation. The quasi bicircular problem is a variation of the restricted four body problem where the three primaries moves in a quasi circular motion around their centre of mass. In this work, we consider the Earth-Moon as primaries bodies of the restricted three body problem and the Earth-Moon-Sun as primaries bodies of the quasi bicircular problem. In both, the massless body is a spatial vehicle. In the restricted three body problem there are five equilibrium points that are well known as the Lagrangian points. But our interest is connected to the motion in a vicinity of L1, which is the inner collinear point. The Liapounov's theorem guarantees the existence of periodic solutions around the equilibrium point. These solutions appear as plane or tridimensional periodic orbits around L1, the spatial one as known Halo orbit. In the quasi bicircular problem, the L1 point appears as periodic orbit with small amplitude and solar period. The objective is determine transfer orbits to put a space vehicle into Halo orbit in both dynamical systems, in the three and four body problem. The Halo and the parking orbits are chosen to be equivalent in both models. To attempt our objective we have applied the two points boundary value problem where the boundary points are one on the parking orbit and the another one is on the Halo orbit. In this formulation there are many solutions that can be found, but if we establish a time constraint the solution set is
Four-body interaction energy for compressed solid krypton from quantum theory.
Tian, Chunling; Wu, Na; Liu, Fusheng; Saxena, Surendra K; Zheng, Xingrong
2012-07-28
The importance of the four-body contribution in compressed solid krypton was first evaluated using the many-body expansion method and the coupled cluster theory with full single and double excitations plus perturbative treatment of triples. All different four-atom clusters existing in the first- and second-nearest neighbor shells of face-centered cubic krypton were considered, and both self-consistent-field Hartree-Fock and correlation parts of the four-body interaction were accurately determined from the ambient conditions up to eightfold volume compression. We find that the four-body interaction energy is negative at compression ratio lower than 2, where the dispersive forces play a dominant role. With increasing the compression, the four-body contribution becomes repulsive and significantly cancels the over-softening effects of the three-body potential. The obtained equation of state (EOS) was compared with the experiments and the density-functional theory calculations. It shows that combination of the four-body effects with two- and three-body interactions leads to an excellent agreement with EOS measurements throughout the whole experimental range 0-130 GPa, and extends the prediction to 300 GPa.
Production of 6He and 9Be by radiative capture and four-body recombination
NASA Astrophysics Data System (ADS)
de Diego, R.; Garrido, E.; Fedorov, D. V.; Jensen, A. S.
2014-06-01
In this work we estimate the production rates for the three-body radiative capture processes α + n + n → 6He + γ and α + α + n → 9Be + γ, as well as the four-body recombination reactions α + α + n + n → 6He + α, α + n + n + n → 6He + n, α + α + n + n → 9Be + n and α + α + α + n → BeBe + α. These processes compete as a source of 6He and 9Be. The hyperspherical adiabatic expansion method is used. With this method no assumption is made about the capture mechanism. Both sequential and direct capture are included. The production rates for the radiative and the four-body recombination processes are found to be comparable for a mass density of about 107g/cm3 ( ˜ 1030 neutrons/cm3) and temperatures of a few GK.
Three- and four-body nonadditivities in nucleic acid tetramers: a CCSD(T) study
Pitonak, Michal; Neogrady, Pavel; Hobza, Pavel
2009-12-18
Three- and four-body nonadditivities in the uracil tetramer (in DNA-like geometry) and the GC step (in crystal geometry) were investigated at various levels of the wave-function theory: HF, MP2, MP3, L-CCD, CCSD and CCSD(T). All of the calculations were performed using the 6-31G**(0.25,0.15) basis set, whereas the HF, MP2 and the MP3 nonadditivities were, for the sake of comparison, also determined with the much larger aug-cc-pVDZ basis set. The HF and MP2 levels do not provide reliable values for many-body terms, making it necessary to go beyond the MP2 level. The benchmark CCSD(T) three- and four-body nonadditivities are reasonably well reproduced at the MP3 level, and almost quantitative agreement is obtained (fortuitously) either on the L-CCD level or as an average of the MP3 and the CCSD results. Reliable values of many-body terms (especially their higher-order correlation contributions) are obtained already when the rather small 6-31G**(0.25,0.15) basis set is used. The four-body term is much smaller when compared to the three-body terms, but it is definitely not negligible, e.g. in the case of the GC step it represents about 16% of all of the three- and four-body terms. While investigating the geometry dependence of many-body terms for the GG step at the MP3/6-31G**(0.25,0.15) level, we found that it is necessary to include at least three-body terms in the determination of optimal geometry parameters.
Recurrence formulas for fully exponentially correlated four-body wave functions
NASA Astrophysics Data System (ADS)
Harris, Frank E.
2009-03-01
Formulas are presented for the recursive generation of four-body integrals in which the integrand consists of arbitrary integer powers (≥-1) of all the interparticle distances rij , multiplied by an exponential containing an arbitrary linear combination of all the rij . These integrals are generalizations of those encountered using Hylleraas basis functions and include all that are needed to make energy computations on the Li atom and other four-body systems with a fully exponentially correlated Slater-type basis of arbitrary quantum numbers. The only quantities needed to start the recursion are the basic four-body integral first evaluated by Fromm and Hill plus some easily evaluated three-body “boundary” integrals. The computational labor in constructing integral sets for practical computations is less than when the integrals are generated using explicit formulas obtained by differentiating the basic integral with respect to its parameters. Computations are facilitated by using a symbolic algebra program (MAPLE) to compute array index pointers and present syntactically correct FORTRAN source code as output; in this way it is possible to obtain error-free high-speed evaluations with minimal effort. The work can be checked by verifying sum rules the integrals must satisfy.
Quantum phases of one-dimensional Hubbard models with three- and four-body couplings
NASA Astrophysics Data System (ADS)
Dolcini, Fabrizio; Montorsi, Arianna
2013-09-01
The experimental advances in cold atomic and molecular gases stimulate the investigation of lattice correlated systems beyond the conventional on-site Hubbard approximation, by possibly including multiparticle processes. We study fermionic extended Hubbard models in a one-dimensional lattice with different types of particle couplings, including also three- and four-body interactions up to nearest neighboring sites. By using the bosonization technique, we investigate the low-energy regime and determine the conditions for the appearance of ordered phases, for arbitrary particle filling. We find that three- and four-body couplings may significantly modify the phase diagram. In particular, diagonal three-body terms that directly couple the local particle densities have qualitatively different effects from off-diagonal three-body couplings originating from correlated hopping, and favor the appearance of a Luther-Emery phase even when two-body terms are repulsive. Furthermore, the four-body coupling gives rise to a rich phase diagram and may lead to the realization of the Haldane insulator phase at half-filling.
A statistical theory for the disruption of four-body systems
NASA Astrophysics Data System (ADS)
Nash, P. E.; Monaghan, J. J.
1980-09-01
A statistical theory based on phase space averaging is used to describe the disruption of bound four-body systems. The dominant final states are assumed to be either two binaries or one binary and two unbound particles. Cut-off parameters are required to render the phase space integrals finite, but they do not have an important effect on the population of a given final state configuration. The relative frequency of the two final states is, however, sensitive to the choice of cut-off. In this paper the mass distributions of the final states are calculated. Other distributions may be easily calculated following the procedure described here.
Four-body treatment of the K-shell positronium formation from multi-electron atoms
NASA Astrophysics Data System (ADS)
Ghanbari-Adivi, Ebrahim; Velayati, Azime
2014-03-01
The four-body Coulomb-Born distorted-wave approximation with correct boundary conditions (CBDW-4B) is applied to the K-shell positronium formation from multi-electron atoms at intermediate and high impact energies. In the present approach, both K-shell electrons are treated as active electrons. For collisions of positrons with helium, carbon, and neon atoms, both the post and prior forms of the transition amplitude are calculated and the corresponding differential and integral cross sections are compared with the results of the three-body version of the formalism (CBDW-3B). In order to investigate the effects of the static electronic correlations on the process, initial bound states of the active electrons in helium atoms are described by Hylleraas and Silverman wave functions. Also for positronium formation from helium atoms the obtained cross sections are compared with the available experimental data and also with the results of the other theories.
Coulomb breakup of 22C in a four-body model
NASA Astrophysics Data System (ADS)
Pinilla, E. C.; Descouvemont, P.
2016-08-01
Breakup cross sections are determined for the Borromean nucleus 22C by using a four-body eikonal model, including Coulomb corrections. Bound and continuum states are constructed within a 20C+n +n three-body model in hyperspherical coordinates. We compute continuum states with the correct asymptotic behavior through the R -matrix method. For the n +n potential, we use the Minnesota interaction. As there is no precise experimental information on 21C, we define different parameter sets for the 20C+n potentials. These parameter sets provide different scattering lengths, and resonance energies of an expected 3 /2+ excited state. Then we analyze the 22C ground-state energy and rms radius, as well as E 1 strength distributions and breakup cross sections. The E 1 strength distribution presents an enhancement at low energies. Its amplitude is associated with the low binding energy, rather than with a three-body resonance. We show that the shape of the cross section at low energies is sensitive to the ground-state properties. In addition, we suggest the existence of a low-energy 2+ resonance, which should be observable in breakup experiments.
Four-body corrected first Born approximation for single charge exchange at high impact energies
NASA Astrophysics Data System (ADS)
Mančev, Ivan
1995-06-01
Single electron capture is investigated by means of the four-body boundary corrected first Born approximation (CB1-4B). The "post" form of the transition amplitude for a general heteronuclear case (Zp; e1) + (ZT; e2) → (Zp; e1, e2) + ZT is derived in the form of readily obtainable two-dimensional real integrals. We investigate the sensitivity of the total cross sections to the choice of ground state wave function for helium-like atoms. Also, the influence of non-captured electron on the final results is studied. As an illustration, the CB1-4B method is used to compute the total cross sections for reactions: H(1s) + H(1s) → H-(1s2) + H+, He+(1s) + H(1s) → He(1s2) + H+ and He+(1s) + He+(1s) → He(1s2) + α. The theoretical cross sections are found to be in good agreement with the available experimental data.
Search for CP violation in singly Cabibbo suppressed four-body D decays
Martinelli, Maurizio
2011-02-01
We search for CP violation in a sample of 4.7 x 10^{4} singly Cabibbo suppressed D^{0} → K^{+} K^{-} π^{+}π^{-} decays and 1.8(2.6) x 10^{4} D_{(s)}^{+} → K_{S}^{0} K^{+} π^{+} π^{-} decays. CP violation is searched for in the difference between the T-odd asymmetries, obtained using triple product correlations, measured for D and _{D} decays. The measured CP violation parameters are A_{T}(D^{0}) = (1.0 ± 5.1(stat) ± 4.4(syst)) x 10^{-3}, A_{T}(D^{+}) = (-11.96 ± 10.04(stat) ± 4.81(syst)) x 10^{-3} and A_{T}(D_{s}^{+}) = (-13.57 ± 7.67(stat) ± 4.82(syst)) x 10^{-3}. This search for CP violation showed that the T-odd correlations are a powerful tool to measure the CP violating observable A_{T}. The relative simplicity of an analysis based on T-odd correlations and the high quality results that can be obtained, allow to consider this tool as fundamental to search for CP violation in four-body decays. Even if the CP violation has not been found, excluding any New Physics effect to the sensitivity of about 0.5%, it is still worth to search for CP violation in D decays. The high statistics that can be obtained at the LHC or by the proposed high luminosity B-factories, make this topic to be considered in high consideration by experiments such as LHCb, SuperB or SuperBelle. The results outlined in this thesis strongly suggest to include a similar analysis into the Physics program of these experiments.
NASA Astrophysics Data System (ADS)
Machuy, A.; Prado, A.; Stuchi, T.
A gravitational capture occurs when a spacecraft or any particle with negligible mass change from a hyperbolic orbit with a small positive energy around a celestial body into an elliptic orbit with a small negative energy without the use of any propulsive system The force responsible for this modification in the orbit of the spacecraft is the gravitational force of the third and the fourth bodies involved in the dynamics In this way those forces are used as a zero cost control equivalent to a continuous thrust applied in the spacecraft One of the most important applications of this property is the construction of trajectories to the Moon The concept of gravitational capture is used together with the basic ideas of the gravity-assisted maneuver and the bi-elliptic transfer orbit to generate a trajectory that requires a fuel consumption smaller than the one required by the Hohmann transfer This maneuver consists of the following steps i the spacecraft is launched from an initial circular orbit with radius r 0 to an elliptic orbit that crosses the Moon s path ii a Swing-By with the Moon is used to increase the apoapsis of the elliptic orbit This step completes the first part of the bi-elliptic transfer with some savings in Delta V due to the energy gained from the Swing-By iii With the spacecraft at the apoapsis a second very small impulse is applied to rise the periapsis to the Earth-Moon distance The solar effects can reduce even more the magnitude of this impulse iv The transfer is completed with the gravitational capture of
User's guide to four-body and three-body trajectory optimization programs
NASA Technical Reports Server (NTRS)
Pu, C. L.; Edelbaum, T. N.
1974-01-01
A collection of computer programs and subroutines written in FORTRAN to calculate 4-body (sun-earth-moon-space) and 3-body (earth-moon-space) optimal trajectories is presented. The programs incorporate a variable step integration technique and a quadrature formula to correct single step errors. The programs provide capability to solve initial value problem, two point boundary value problem of a transfer from a given initial position to a given final position in fixed time, optimal 2-impulse transfer from an earth parking orbit of given inclination to a given final position and velocity in fixed time and optimal 3-impulse transfer from a given position to a given final position and velocity in fixed time.
Rodriguez-Gallardo, M.; Arias, J. M.; Moro, A. M.; Gomez-Camacho, J.; Thompson, I. J.; Tostevin, J. A.
2010-04-26
The recently developed four-body continuum-discretized coupled-channels (CDCC) method, making use of the binning procedure, is applied to the reaction {sup 6}He+{sup 64}Zn at 13.6 MeV (around the Coulomb barrier). Excellent agreement with available elastic data is found.
NASA Astrophysics Data System (ADS)
Giersz, M.; Spurzem, R.
2003-08-01
Spherically symmetric equal-mass star clusters containing a large number of primordial binaries are studied using a hybrid method, consisting of a gas dynamical model for single stars and a Monte Carlo treatment for relaxation of binaries and the setup of close resonant and fly-by encounters of single stars with binaries and binaries with each other (three- and four-body encounters). What differs from our previous work is that each encounter is being integrated using a highly accurate direct few-body integrator which uses regularized variables. Hence we can study the systematic evolution of individual binary orbital parameters (eccentricity, semimajor axis) and differential and total cross-sections for hardening, dissolution or merging of binaries (minimum distance) from a sampling of several tens of thousands of scattering events as they occur in real cluster evolution, including mass segregation of binaries, gravothermal collapse and re-expansion, a binary burning phase and ultimately gravothermal oscillations. For the first time we are able to present empirical cross-sections for eccentricity variation of binaries in close three- and four-body encounters. It is found that a large fraction of three- and four-body encounters result in merging. Eccentricities are generally increased in strong three- and four-body encounters and there is a characteristic scaling law ~ exp (4efin) of the differential cross-section for eccentricity changes, where efin is the final eccentricity of the binary, or harder binary for four-body encounters. Despite these findings the overall eccentricity distribution remains thermal for all binding energies of binaries, which is understood from the dominant influence of resonant encounters. Previous cross-sections obtained by Spitzer and Gao for strong encounters can be reproduced, while for weak encounters non-standard processes such as the formation of hierarchical triples occur.
NASA Astrophysics Data System (ADS)
Neri, M.; Martínez, A.; Juárez-León, C.; Torres, J. J.; Flores-Mendieta, Rubén
2016-09-01
The four-body contribution of the model-independent radiative corrections to the Dalitz plot of the semileptonic decays of neutral kaons are computed to order (α /π )(q /M1) , where q is the momentum transfer and M1 is the kaon mass. The final result is presented in two forms. The first one is given in terms of the triple integration of the bremsstrahlung photon ready to be performed numerically; the second one is a fully analytical expression. This paper is organized to make it accessible and reliable in the analysis of the Dalitz plot of precision experiments involving kaons and is not compromised to fixing the form factors at predetermined values. As a byproduct, gathering together three- and four-body contributions of radiative corrections yields, through a least-squares fit to the measured kaon decay rates, the value f+K0π-|Vu s|=0.2168 (3 ) .
NASA Astrophysics Data System (ADS)
Mančev, Ivan; Milojević, Nenad; Belkić, Dževad
2015-06-01
Single charge exchange in collisions between bare projectiles and heliumlike atomic systems at intermediate and high incident energies is examined by using the four-body formalism of the first- and second-order theories. The main purpose of the present study is to investigate the relative importance of the intermediate ionization continua of the captured electron compared to the usual direct path of the single electron transfer from a target to a projectile. In order to achieve this goal, comprehensive comparisons are made between the four-body boundary-corrected continuum-intermediate-states (BCIS-4B) method and the four-body boundary-corrected first Born (CB1-4B) method. The perturbation potential is the same in the CB1-4B and BCIS-4B methods. Both methods satisfy the correct boundary conditions in the entrance and exit channels. However, unlike the CB1-4B method, the second-order BCIS-4B method takes into account the electronic Coulomb continuum-intermediate states in either the entrance or the exit channel depending on whether the post or the prior version of the transition amplitude is used. Hence, by comparing the results from these two theories, the relative importance of the intermediate ionization electronic continua can be assessed within the four-body formalism of scattering theory. The BCIS-4B method predicts the usual second-order effect through double scattering of the captured electron on two nuclei as a quantum-mechanical counterpart of the Thomas classical two-step, billiard-type collision. The physical mechanism for this effect in the BCIS-4B method is also comprised of two steps such that ionization occurs first. This is followed by capture of the electron by the projectile with both processes taking place on the energy shell. Moreover, the role of the second, noncaptured electron in a heliumlike target is revisited. To this end, the BCIS-4B method describes the effect of capture of one electron by the interaction of the projectile nucleus with
Link, J M; Reyes, M; Yager, P M; Anjos, J C; Bediaga, I; Göbel, C; Magnin, J; Massafferi, A; de Miranda, J M; Pepe, I M; dos Reis, A C; Simão, F R; Carrillo, S; Casimiro, E; Sánchez-Hernández, A; Uribe, C; Vázquez, F; Cinquini, L; Cumalat, J P; O'Reilly, B; Ramirez, J E; Vaandering, E W; Butler, J N; Cheung, H W; Gaines, I; Garbincius, P H; Garren, L A; Gottschalk, E; Kasper, P H; Kreymer, A E; Kutschke, R; Bianco, S; Fabbri, F L; Sarwar, S; Zallo, A; Cawlfield, C; Kim, D Y; Rahimi, A; Wiss, J; Gardner, R; Chung, Y S; Kang, J S; Ko, B R; Kwak, J W; Lee, K B; Park, H; Alimonti, G; Boschini, M; Caccianiga, B; D'Angelo, P; DiCorato, M; Dini, P; Giammarchi, M; Inzani, P; Leveraro, F; Malvezzi, S; Menasce, D; Mezzadri, M; Milazzo, L; Moroni, L; Pedrini, D; Pontoglio, C; Prelz, F; Rovere, M; Sala, A; Sala, S; Davenport, T F; Agostino, L; Arena, V; Boca, G; Bonomi, G; Gianini, G; Liguori, G; Merlo, M; Pantea, D; Ratti, S P; Riccardi, C; Segoni, I; Viola, L; Vitulo, P; Hernandez, H; Lopez, A M; Mendez, H; Mendez, L; Mirles, A; Montiel, E; Olaya, D; Paris, A; Quinones, J; Rivera, C; Xiong, W; Zhang, Y; Wilson, J R; Cho, K; Handler, T; Engh, D; Hosack, M; Johns, W E; Nehring, M; Sheldon, P D; Stenson, K; Webster, M; Sheaff, M
2001-10-15
We have studied hadronic four-body decays of D(+) and D(+)(s) mesons with a K(S) in the final state using data recorded during the 1996-1997 fixed-target run of the Fermilab high energy photoproduction experiment FOCUS. We report a new branching ratio measurement of gamma(D(+)-->K(S)K-pi(+)pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0768+/-0.0041+/-0.0032. We make the first observation of three new decay modes with branching ratios gamma(D(+)-->K(S)K+pi(+)pi(-))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0562+/-0.0039+/-0.0040, gamma(D(+)-->K(S)K+K-pi(+))/gamma(D(+)-->K(S)pi(+)pi(+)pi(-)) = 0.0077+/-0.0015+/-0.0009, and gamma(D(+)(s)-->K(S)K+pi(+)pi(-))/gamma(D(+)(s)-->K(S)K-pi(+)pi(+)) = 0.586+/-0.052+/-0.043, where in each case the first error is statistical and the second error is systematic. PMID:11690200
Non-Collision Singularities in the Planar Two-Center-Two-Body Problem
NASA Astrophysics Data System (ADS)
Xue, Jinxin; Dolgopyat, Dmitry
2016-08-01
In this paper, we study a restricted four-body problem called the planar two-center-two-body problem. In the plane, we have two fixed centers Q 1 and Q 2 of masses 1, and two moving bodies Q 3 and Q 4 of masses {μ≪ 1}. They interact via Newtonian potential. Q 3 is captured by Q 2, and Q 4 travels back and forth between two centers. Based on a model of Gerver, we prove that there is a Cantor set of initial conditions that lead to solutions of the Hamiltonian system whose velocities are accelerated to infinity within finite time avoiding all earlier collisions. This problem is a simplified model for the planar four-body problem case of the Painlevé conjecture.
Internal or shape coordinates in the {ital n}-body problem
Littlejohn, R.G.; Reinsch, M.
1995-09-01
The construction of global shape coordinates for the {ital n}-body problem is considered. Special attention is given to the three- and four-body problems. Quantities, including candidates for coordinates, are organized according to their transformation properties under so-called democracy transformations (orthogonal transformations of Jacobi vectors). Important submanifolds of shape space are identified and their topology studied, including the manifolds upon which shapes are coplanar or collinear, and the manifolds upon which the moment of inertia tensor is degenerate.
... often, it could be a sign of a balance problem. Balance problems can make you feel unsteady or as ... fall-related injuries, such as hip fracture. Some balance problems are due to problems in the inner ...
Reducible chiral four-body interactions in nuclear matter
NASA Astrophysics Data System (ADS)
Kaiser, N.; Milkus, R.
2016-01-01
The method of unitary transformations generates five classes of leading-order reducible chiral four-nucleon interactions which involve pion exchanges and a spin-spin contact term. Their first-order contributions to the energy per particle of isospin-symmetric nuclear matter and pure neutron matter are evaluated in detail. For most of the closed four-loop diagrams the occurring integrals over four Fermi spheres can be reduced to easily manageable one- or two-parameter integrals. One finds substantial compensations among the different contributions arising from 2-ring and 1-ring diagrams. Altogether, the net attraction generated by the chiral four-nucleon interaction does not exceed values of -1.3 MeV for densities ρ < 2ρ0.
Four-body continuum-discretized coupled-channels calculations
Rodriguez-Gallardo, M.; Arias, J. M.; Moro, A. M.; Gomez-Camacho, J.; Thompson, I. J.; Tostevin, J. A.
2009-11-15
The development of a continuum-bin scheme of discretization for three-body projectiles is necessary for studies of reactions of Borromean nuclei such as {sup 6}He within the continuum-discretized coupled-channels approach. Such a procedure, for constructing bin states on selected continuum energy intervals, is formulated and applied for the first time to reactions of a three-body projectile. The continuum representation uses the eigenchannel expansion of the three-body S matrix. The method is applied to the challenging case of the {sup 6}He+{sup 208}Pb reaction at 22 MeV, where an accurate treatment of both the Coulomb and the nuclear interactions with the target is necessary.
Four-body trajectory optimization. [fuel optimal computer programs
NASA Technical Reports Server (NTRS)
Pu, C. L.; Edelbaum, T. N.
1975-01-01
The two methods which are suitable for use in a 4-body trajectory optimization program are both multiconic methods. They include an approach due to Wilson (1970) and to Byrnes and Hooper (1970) and a procedure developed by Stumpff and Weiss (1968). The various steps in a trajectory optimization program are discussed, giving attention to variable step integration, the correction of errors by quadrature formulas, questions of two-impulse transfer, three-impulse transfer, and two examples which illustrate the implementation of the computational approaches.
Electroweak Structure of Three- and Four-Body Nuclei
Laura Marcucci
2000-06-01
This work reports results for (i) the elastic electromagnetic form factors of the trin- of ucleons; (ii) the nuclear response functions of interest in ~ experiments, 3 He(~e; e 0 ) experiments, at VERSITY excitation energies below the deuteron breakup threshold; (iii) the astrophysical ark S-factor for proton weak capture on 3 He (the hep reaction). The initial and nal using state wave functions are calculated using the correlated hyperspherical harmonics onsisting method, from a realistic Hamiltonian consisting of the Argonne v 18 two-nucleon uclear and Urbana IX three-nucleon interactions. The nuclear electroweak charge and ts. current operators include one- and many-body components. The predicted mag- netic form factor of 3 H, charge form factors and static properties of both 3 H and ntal 3 He, are in satisfactory agreement with the experimental data. However, the po- sition of the zero in the magnetic form factor of 3 He is underpredicted by theory. disintegration The calculated nuclear response functions in 3 He electrodisintegration at thresh- er old are in good agreement with the experimental data, which have however rather s large errors. Finally, the astrophysical S-factor for the hep reaction is predicted ortant ' 4.5 larger than the value adopted in the standard-solar-model, with important consequences for the solar neutrino spectrum measured by the Super-Kamiokande collaboration.
... version of this page please turn Javascript on. Balance Problems About Balance Problems Have you ever felt dizzy, lightheaded, or ... dizziness problem during the past year. Why Good Balance is Important Having good balance means being able ...
... daily activities, get around, and exercise. Having a problem with walking can make daily life more difficult. ... walk is called your gait. A variety of problems can cause an abnormal gait and lead to ...
... re not getting enough air. Sometimes mild breathing problems are from a stuffy nose or hard exercise. ... emphysema or pneumonia cause breathing difficulties. So can problems with your trachea or bronchi, which are part ...
... ankles and toes. Other types of arthritis include gout or pseudogout. Sometimes, there is a mechanical problem ... for more information on osteoarthritis, rheumatoid arthritis and gout. How Common are Joint Problems? Osteoarthritis, which affects ...
ERIC Educational Resources Information Center
Hale, Norman; Lindelow, John
Chapter 12 in a volume on school leadership, this chapter cites the work of several authorities concerning problem-solving or decision-making techniques based on the belief that group problem-solving effort is preferable to individual effort. The first technique, force-field analysis, is described as a means of dissecting complex problems into…
... our e-newsletter! Aging & Health A to Z Balance Problems Basic Facts & Information What are Balance Problems? Having good balance means being able to ... Only then can you “keep your balance.” Why Balance is Important Your feelings of dizziness may last ...
ERIC Educational Resources Information Center
Foster, Colin
2012-01-01
This is the story of a real problem, not a problem that is contrived, or invented for the convenience of the appropriate planning tool. This activity by a group of students, defined simply as "8FN", might be likened to an "end of term concert". If you just happened to be a delegate at the ATM Conference 2003 you might remember the analogy. Social…
... This flow chart will help direct you if hearing loss is a problem for you or a family ... may damage the inner ear. This kind of hearing loss is called OCCUPATIONAL. Prevent occupational hearing loss by ...
... treated differently. Common thyroid disorders and problems include: Hypothyroidism Hypothyroidism is a disorder in which your thyroid doesn’ ... normal after you get better. If you have hypothyroidism, however, the levels of T4 in your blood ...
... our e-newsletter! Aging & Health A to Z Kidney Problems Basic Facts & Information The kidneys are two ... the production of red blood cells. What are Kidney Diseases? For about one-third of older people, ...
... For Consumers Consumer Information by Audience For Women Sleep Problems Share Tweet Linkedin Pin it More sharing ... PDF 474KB) En Español Medicines to Help You Sleep Tips for Better Sleep Basic Facts about Sleep ...
... a person's ability to speak clearly. Some Common Speech Disorders Stuttering is a problem that interferes with fluent ... is a language disorder, while stuttering is a speech disorder. A person who stutters has trouble getting out ...
... Inverted nipple; Nipple problems Images Female breast Intraductal papilloma Mammary gland Abnormal discharge from the nipple Normal ... 8. Read More Breast cancer Endocrine glands Intraductal papilloma Update Date 11/16/2014 Updated by: Cynthia ...
ERIC Educational Resources Information Center
Murphy, Pat, Ed.
1993-01-01
"Exploring" is a magazine of science, art, and human perception, produced by Exploratorium in collaboration with other participating museums. This issue focuses on puzzles and problem solving. Brain teasers, puzzles, and the strategies for solving them are included. Features include: (1) "Homework Assignment #3" (Paul Doherty); (2) "The Case of…
ERIC Educational Resources Information Center
Connors, G. Patrick
Heat problems and heat cramps related to jogging can be caused by fluid imbalances, medications, dietary insufficiency, vomiting or diarrhea, among other factors. If the condition keeps reoccurring, the advice of a physician should be sought. Some preventive measures that can be taken include: (1) running during the cooler hours of the day; (2)…
NASA Technical Reports Server (NTRS)
Kussner, H G
1937-01-01
The present report deals with a number of the main problems requiring solution in the development of helicopters and concerning the lift, flying performance, stability, and drive. A complete solution is given for the stability of the helicopter with rigid blades and control surfaces. With a view to making a direct-lift propeller sufficient without the addition of auxiliary propellers, the "flapping drive" is assessed and its efficiency calculated.
Classification of periodic orbits in the four- and five-body problems.
Broucke, Roger A
2004-05-01
The research described in this paper was motivated by the new types of periodic solutions that were recently discovered by Moore, Chenciner, Montgomery, and Simo in the three-body and the N-body problem (with large N). We attempt to classify the various types of periodic orbits, in the inertial frame, on the basis of an extensive numerical exploration. We have started an exploration of the four-body problem, where the classification of types of periodic orbits is more involved. We immediately found those orbits with symmetry with respect to the x-axis, the y-axis, or both. Complete quadruple interplay, or a triple system around a single mass is possible. Finally, what seems to be the most frequent, two binary systems in orbit around the general center of mass. However, the last group can be separated into several subgroups. We have, for instance, the case of two masses on one orbit and the two other masses on another orbit. This is again a partial choreography. We then have the case of double binary choreographies: two binary systems in which all four masses travel on one single curve. To realize this situation, a certain commensurability is needed between the overall period and the period of each binary system. The binary system makes an odd integer number, q, of revolutions during a general period. We computed many cases from q = 5 to 97. This indicates that we have a discrete infinity of choreographies. The choreography q = 5 is an especially remarkable star-shaped curve. Actually, we have two such infinite families, one with corotational and the other with contrarotational motions. We show that they can be justified by simple Keplerian approximations. Finally, we mention that our work depends heavily on the existence of symmetries. They simplify the algorithms for finding periodic orbits and they play an important role in the classification. In the four-body problem with equal masses, we have five different types of symmetries. In addition to the well
Problems with "n"th-Term Problems
ERIC Educational Resources Information Center
Matteson, Shirley M.
2010-01-01
An nth-term problem involves a sequence. Students must determine which expression will allow them to calculate the nth position of the sequence. To solve such problems, students are to find "a rule that determines the number of elements in a step from the step number." These types of problems help students develop concepts of functions, variables,…
Class and Home Problems: Optimization Problems
ERIC Educational Resources Information Center
Anderson, Brian J.; Hissam, Robin S.; Shaeiwitz, Joseph A.; Turton, Richard
2011-01-01
Optimization problems suitable for all levels of chemical engineering students are available. These problems do not require advanced mathematical techniques, since they can be solved using typical software used by students and practitioners. The method used to solve these problems forces students to understand the trends for the different terms…
f AQ FREQUENTLY ASKED QUESTIONS FAQ178 GYNECOLOGIC PROBLEMS Mammography and Other Screening Tests for Breast Problems • What ... used to screen for breast problems? • What is mammography? • Why is mammography done? • When should I start ...
There are many problems that can keep a woman from enjoying sex. They include Lack of sexual ... concerns about marriage or relationship problems. For some women, the problem results from past sexual trauma. Occasional ...
... this page please turn Javascript on. Problems with Smell About Problems with Smell Our sense of smell helps us enjoy life. ... sec Click to watch this video Aging and Smell Loss Problems with smell increase as people get ...
ERIC Educational Resources Information Center
Reeves, Charles A.
2000-01-01
Uses the chicken problem for sixth grade students to scratch the surface of systems of equations using intuitive approaches. Provides students responses to the problem and suggests similar problems for extensions. (ASK)
Performance Contracting: Problem Definition and Problem Resolution.
ERIC Educational Resources Information Center
Zaharis, James K.; And Others
This skill laboratory provides a technique for problem definition and alternative methods to gather pertinent data that surrounds a given situation. Seven skills are discussed including Kaufman's tri-level needs assessment model, intergroup building, organizational slice, force field analysis, brainstorming, problem definition, and conflict…
Problem? "No Problem!" Solving Technical Contradictions
ERIC Educational Resources Information Center
Kutz, K. Scott; Stefan, Victor
2007-01-01
TRIZ (pronounced TREES), the Russian acronym for the theory of inventive problem solving, enables a person to focus his attention on finding genuine, potential solutions in contrast to searching for ideas that "may" work through a happenstance way. It is a patent database-backed methodology that helps to reduce time spent on the problem,…
Quadratic eigenvalue problems.
Walsh, Timothy Francis; Day, David Minot
2007-04-01
In this report we will describe some nonlinear eigenvalue problems that arise in the areas of solid mechanics, acoustics, and coupled structural acoustics. We will focus mostly on quadratic eigenvalue problems, which are a special case of nonlinear eigenvalue problems. Algorithms for solving the quadratic eigenvalue problem will be presented, along with some example calculations.
Extension of Expiration Dates for Four Body System Listings. Final rule.
2016-08-01
We are extending the expiration dates of the following body systems in the Listing of Impairments (listings) in our regulations: Musculoskeletal System, Cardiovascular System, Digestive System, and Skin Disorders. We are making no other revisions to these body systems in this final rule. This extension ensures that we will continue to have the criteria we need to evaluate impairments in the affected body systems at step three of the sequential evaluation processes for initial claims and continuing disability reviews. PMID:27487579
Ferlaino, F; Knoop, S; Mark, M; Berninger, M; Schöbel, H; Nägerl, H-C; Grimm, R
2008-07-11
We study inelastic collisions in a pure, trapped sample of Feshbach molecules made of bosonic cesium atoms in the quantum halo regime. We measure the relaxation rate coefficient for decay to lower-lying molecular states and study the dependence on scattering length and temperature. We identify a pronounced loss minimum with varying scattering length along with a further suppression of loss with decreasing temperature. Our observations provide insight into the physics of a few-body quantum system that consists of four identical bosons at large values of the two-body scattering length. PMID:18764179
Four-body recombination in organic bulk heterojunction solar cells: an alternative interpretation
NASA Astrophysics Data System (ADS)
Szmytkowski, Jȩdrzej
2013-05-01
We demonstrate a new interpretation of the previously reported quadrimolecular recombination in organic bulk heterojunction solar cells. It is suggested that the recently described (Szmytkowski 2012 Phys. Status Solidi RRL 6 300) interaction between exciton and electron-hole Langevin bound pair formed across the donor-acceptor interface is a four-particle process. This is in opposition to the treatment of this effect as a three-particle phenomenon which might be intuitively expected because one exciton annihilates physically on one charge carrier. An excellent agreement between experimental data and theoretical calculations has been obtained. The novelty of the presented interpretation is of fundamental importance to understand mechanisms which limit the efficiency of organic solar cells.
Benchmark problems and solutions
NASA Technical Reports Server (NTRS)
Tam, Christopher K. W.
1995-01-01
The scientific committee, after careful consideration, adopted six categories of benchmark problems for the workshop. These problems do not cover all the important computational issues relevant to Computational Aeroacoustics (CAA). The deciding factor to limit the number of categories to six was the amount of effort needed to solve these problems. For reference purpose, the benchmark problems are provided here. They are followed by the exact or approximate analytical solutions. At present, an exact solution for the Category 6 problem is not available.
The problem with the species problem.
Ellis, Mark W
2011-01-01
When Charles Darwin convinced the scientific community that species evolve, the long-held essentialist view of each species as fixed was rejected and a clear conceptual understanding of the term was lost. For the next century, a real species problem existed that became culturally entrenched within the scientific community. Although largely solved decades ago, the species problem remains entrenched today due to a suite of factors. Most of the factors that help maintain its perceived intractability have been revealed and logically dismissed; yet this is not widely known so those factors continue to be influential. It is time to recognize this false foundation and relegate the species problem to history.
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IT Problem Management â process responsible for managing Lifecycle of all IT problems. The primary objective is to prevent incidents from occurring and to minimize impact of incidents that cannot...
... review our exit disclaimer . Subscribe Increases in Problem Drinking Alcohol use disorder is becoming more common, a ... the need to better educate people about problem drinking and its treatment. Alcohol use disorder, or AUD, ...
... Disease, and Other Dental Problems Diabetic Eye Disease Diabetes and Foot Problems How can diabetes affect my feet? Too much glucose, also called ... you have any of these signs. How can diabetes change the shape of my feet? Nerve damage ...
ERIC Educational Resources Information Center
Eperson, D. B.
1991-01-01
This section includes eight problems to which the journal invites readers to respond. Problem topics include angles in alternate segments, pentominoes, a new triangle of numbers, cricket scores, symmetrical pentagons, inequalities, a pythagorean dissection, and magic squares. (MDH)
The molecular matching problem
NASA Technical Reports Server (NTRS)
Kincaid, Rex K.
1993-01-01
Molecular chemistry contains many difficult optimization problems that have begun to attract the attention of optimizers in the Operations Research community. Problems including protein folding, molecular conformation, molecular similarity, and molecular matching have been addressed. Minimum energy conformations for simple molecular structures such as water clusters, Lennard-Jones microclusters, and short polypeptides have dominated the literature to date. However, a variety of interesting problems exist and we focus here on a molecular structure matching (MSM) problem.
ERIC Educational Resources Information Center
King, James C.
1988-01-01
This pamphlet discusses group problem solving in schools. Its point of departure is that teachers go at problems from a number of different directions and that principals need to capitalize on those differences and bring a whole range of skills and perceptions to the problem-solving process. Rather than trying to get everyone to think alike,…
ERIC Educational Resources Information Center
Capobianco, Brenda M.; Tyrie, Nancy
2009-01-01
In a unique school-university partnership, methods students collaborated with fifth graders to use the engineering design process to build their problem-solving skills. By placing the problem in the context of a client having particular needs, the problem took on a real-world appeal that students found intriguing and inviting. In this article, the…
ERIC Educational Resources Information Center
Linton, Marigold
Previous approaches to the learning problems of American Indian children are viewed as inadequate. An alternative is suggested which emphasizes the problem solution strategies which these children bring to the school situation. Solutions were analyzed in terms of: (1) their probability; (2) their efficiency at permitting a present problem to be…
Exploratory Problems in Mathematics.
ERIC Educational Resources Information Center
Stevenson, Frederick W.
This book attempts to introduce students to the creative aspects of mathematics through exploratory problems. The introduction presents the criteria for the selection of the problems in the book. Criteria indicate that problems should: be immediately attractive, require data to be generated or gathered, appeal to students from junior high school…
Mathematics as Problem Solving.
ERIC Educational Resources Information Center
Soifer, Alexander
This book contains about 200 problems. It is suggested that it be used by students, teachers or anyone interested in exploring mathematics. In addition to a general discussion on problem solving, there are problems concerned with number theory, algebra, geometry, and combinatorics. (PK)
ERIC Educational Resources Information Center
Green, Gary J.
This paper presents two actual problems involving grievance procedures. Both problems involve pending litigation and one of them involves pending arbitration. The first problem occurred in a wealthy Minnesota school district and involved a seniority list. Because of changes in the financial basis for supporting public schools, it became necessary…
Techniques of Problem Solving.
ERIC Educational Resources Information Center
Krantz, Steven G.
The purpose of this book is to teach the basic principles of problem solving in both mathematical and non-mathematical problems. The major components of the book consist of learning to translate verbal discussion into analytical data, learning problem solving methods for attacking collections of analytical questions or data, and building a…
The Second Parameter Problem(s)
NASA Astrophysics Data System (ADS)
Dotter, Aaron
The Second Parameter (2ndP) Problem recognizes the remarkable role played by horizontal branch (HB) morphology in the development of our understanding of globular clusters, and the Galaxy, over the last 50 years. I will describe the historical development of the 2ndP and discuss recent advances that are finally providing some answers. I will discuss how the controversies surrounding the nature of the 2ndP can be reconciled if we acknowledge that there are actually two distinct problems with entirely different solutions.
Pan, Feng; Kasiviswanathan, Shiva
2010-01-01
In the matrix interdiction problem, a real-valued matrix and an integer k is given. The objective is to remove k columns such that the sum over all rows of the maximum entry in each row is minimized. This combinatorial problem is closely related to bipartite network interdiction problem which can be applied to prioritize the border checkpoints in order to minimize the probability that an adversary can successfully cross the border. After introducing the matrix interdiction problem, we will prove the problem is NP-hard, and even NP-hard to approximate with an additive n{gamma} factor for a fixed constant {gamma}. We also present an algorithm for this problem that achieves a factor of (n-k) mUltiplicative approximation ratio.
ROV overcomes deepwater problems
Frisbie, F.R.; Hughes, E.W.
1984-09-01
The use of remotely operated vehicles (ROVs) in supportive drill ships operating in more than 200 meters of water poses severe technical and operational problems. Defining these problems beforehand and addressing them during design, manufacture, testing and installation ensures a functional and effective support capability. Such problems as the availability of desk space, and the subsequent installation, maintenance, and the launch/recovery of the system are described.
Tactical missile turbulence problems
NASA Technical Reports Server (NTRS)
Dickson, Richard E.
1987-01-01
Of particular interest is atmospheric turbulence in the atmospheric boundary layer, since this affects both the launch and terminal phase of flight, and the total flight for direct fire systems. Brief discussions are presented on rocket artillery boost wind problems, mean wind correction, turbulent boost wind correction, the Dynamically Aimed Free Flight Rocket (DAFFR) wind filter, the DAFFR test, and rocket wake turbulence problems. It is concluded that many of the turbulence problems of rockets and missiles are common to those of aircraft, such as structural loading and control system design. However, these problems have not been solved at this time.
Egorov, Yurii V
2013-04-30
We consider the classical problem on the tallest column which was posed by Euler in 1757. Bernoulli-Euler theory serves today as the basis for the design of high buildings. This problem is reduced to the problem of finding the potential for the Sturm-Liouville equation corresponding to the maximum of the first eigenvalue. The problem has been studied by many mathematicians but we give the first rigorous proof of the existence and uniqueness of the optimal column and we give new formulae which let us find it. Our method is based on a new approach consisting in the study of critical points of a related nonlinear functional. Bibliography: 6 titles.
Known TCP Implementation Problems
NASA Technical Reports Server (NTRS)
Paxson, Vern (Editor); Allman, Mark; Dawson, Scott; Fenner, William; Griner, Jim; Heavens, Ian; Lahey, K.; Semke, J.; Volz, B.
1999-01-01
This memo catalogs a number of known TCP implementation problems. The goal in doing so is to improve conditions in the existing Internet by enhancing the quality of current TCP/IP implementations. It is hoped that both performance and correctness issues can be resolved by making implementors aware of the problems and their solutions. In the long term, it is hoped that this will provide a reduction in unnecessary traffic on the network, the rate of connection failures due to protocol errors, and load on network servers due to time spent processing both unsuccessful connections and retransmitted data. This will help to ensure the stability of the global Internet. Each problem is defined as follows: Name of Problem The name associated with the problem. In this memo, the name is given as a subsection heading. Classification one or more problem categories for which the problem is classified: "congestion control", "performance", "reliability", "resource management". Description A definition of the problem, succinct but including necessary background material. Significance A brief summary of the sorts of environments for which the problem is significant.
Specific Pronunciation Problems.
ERIC Educational Resources Information Center
Avery, Peter; And Others
1987-01-01
Reviews common pronunciation problems experienced by learners of English as a second language who are native speakers of Vietnamese, Cantonese, Spanish, Portuguese, Italian, Polish, Greek, and Punjabi. (CB)
Crystalline silica: Old problem, new problem
Burst, J.F. )
1993-03-01
Known as an industrial health hazard for centuries, crystalline silica has recently gained enhanced recognition as a threat to human health by being classified as a 2A probable carcinogen'' by The International Agency for Research on Cancer. Its maximum allowable concentration as an impurity is established as 0.1%. This has led to consternation in the mining and mineral industries inasmuch as the accuracy of methodology available to measure crystalline silica content at this level in heterogeneous matrices has been severely questioned and unlabeled products distributed with crystalline silica contents in excess of 0.1% are considered in violation of the Hazard Communication Standard. Three problems exist: (1) defining acceptable reference standards; (2) establishing adequate measurement procedures; (3) marketing products in compliance with State and Federal regulations. A review and update of these problems has been developed for the guidance of quarry operators and mineral product manufacturers.
Identifying Adolescent Sleep Problems
Short, Michelle A.; Gradisar, Michael; Gill, Jason; Camfferman, Danny
2013-01-01
Objectives To examine the efficacy of self-report and parental report of adolescent sleep problems and compare these findings to the incidence of adolescents who fulfill clinical criteria for a sleep problem. Sleep and daytime functioning factors that predict adolescents’ self-identification of a sleep problem will also be examined. Method 308 adolescents (aged 13–17 years) from eight socioeconomically diverse South Australian high schools participated in this study. Participants completed a survey battery during class time, followed by a 7-day Sleep Diary and the Flinders Fatigue Scale completed on the final day of the study. Parents completed a Sleep, Medical, Education and Family History Survey. Results The percentage of adolescents fulfilling one or more of the criteria for a sleep problem was inordinately high at 66%. Adolescent self-reporting a sleep problem was significantly lower than the adolescents who had one or more of the clinical criteria for a sleep problem (23.1% vs. 66.6%; χ2 = 17.46, p<.001). Parental report of their adolescent having a sleep problem was significantly lower than adolescent self-report (14.3% vs. 21.1%, p<.001). Adolescents who reported unrefreshing sleep were 4.81 times more likely to report a sleep problem. For every hour that bedtime was delayed, the odds of self-reporting a sleep problem increased by 1.91 times, while each additional 10 minutes taken to fall asleep increased the odds 1.40 times. Conclusion While many adolescents were found to have sleep patterns indicative of a sleep problem, only a third of this number self-identify having a sleep problem, while only a sixth of this number are indicated by parental report. This study highlights important features to target in future sleep education and intervention strategies for both adolescents and parents. PMID:24086501
ERIC Educational Resources Information Center
Mann, Philip H.; Suiter, Patricia A.
This teacher's guide contains a list of general auditory problem areas where students have the following problems: (a) inability to find or identify source of sound; (b) difficulty in discriminating sounds of words and letters; (c) difficulty with reproducing pitch, rhythm, and melody; (d) difficulty in selecting important from unimportant sounds;…
Medical problems affecting musicians.
Potter, P. J.; Jones, I. C.
1995-01-01
The physical demands of performing on musical instruments can cause pain, sensory loss, and lack of coordination. Five cases illustrate common problems. Knowledge of the interaction between the technique of playing the instrument and the particular musician can help physicians diagnose and resolve problems. Images Figure 1 PMID:8680295
ERIC Educational Resources Information Center
Martinez, Michael E.
1998-01-01
Many important human activities involve accomplishing goals without a script. There is no formula for true problem-solving. Heuristic, cognitive "rules of thumb" are the problem-solver's best guide. Learners should understand heuristic tools such as means-end analysis, working backwards, successive approximation, and external representation. Since…
ERIC Educational Resources Information Center
JEFFRIES, CHARLES
THIS STUDY OF WORLD ILLITERACY BEGINS WITH A BRIEF OUTLINE OF THE NATURE OF THE PROBLEM OF ILLITERACY AND DISCUSSION OF THE SPECIAL TECHNIQUES WHICH HAVE BEEN EVOLVED TO OVERCOME IT. A WORLD MAP OF ILLITERACY PLOTS ILLITERACY IN SPECIFIC AREAS AND COUNTRIES. PAST AND PRESENT EFFORTS TO SOLVE THE PROBLEM (THE PIONEER WORK OF WORK OF MISSIONARIES,…
Current Social Problem Novels.
ERIC Educational Resources Information Center
Kenney, Donald J.
This review of social problem novels for young adults opens with a brief background of the genre, then lists the dominant themes of social problem fiction and nonfiction novels that have been published in the last two years, such as alcoholism, alienation, death, growing up and self-awarness, drugs, and divorce. Other themes mentioned are…
NASA Astrophysics Data System (ADS)
Harper, Kathleen A.; Etkina, Eugenia
2002-10-01
As part of weekly reports,1 structured journals in which students answer three standard questions each week, they respond to the prompt, If I were the instructor, what questions would I ask or problems assign to determine if my students understood the material? An initial analysis of the results shows that some student-generated problems indicate fundamental misunderstandings of basic physical concepts. A further investigation explores the relevance of the problems to the week's material, whether the problems are solvable, and the type of problems (conceptual or calculation-based) written. Also, possible links between various characteristics of the problems and conceptual achievement are being explored. The results of this study spark many more questions for further work. A summary of current findings will be presented, along with its relationship to previous work concerning problem posing.2 1Etkina, E. Weekly Reports;A Two-Way Feedback Tool, Science Education, 84, 594-605 (2000). 2Mestre, J.P., Probing Adults Conceptual Understanding and Transfer of Learning Via Problem Posing, Journal of Applied Developmental Psychology, 23, 9-50 (2002).
Problem Solving in Electricity.
ERIC Educational Resources Information Center
Caillot, Michel; Chalouhi, Elias
Two studies were conducted to describe how students perform direct current (D-C) circuit problems. It was hypothesized that problem solving in the electricity domain depends largely on good visual processing of the circuit diagram and that this processing depends on the ability to recognize when two or more electrical components are in series or…
Teaching through Problem Solving
ERIC Educational Resources Information Center
Fi, Cos D.; Degner, Katherine M.
2012-01-01
Teaching through Problem Solving (TtPS) is an effective way to teach mathematics "for" understanding. It also provides students with a way to learn mathematics "with" understanding. In this article, the authors present a definition of what it means to teach through problem solving. They also describe a professional development vignette that…
ERIC Educational Resources Information Center
Cannon, Lawrence O.; Elich, Joe
In most mathematics problem solving work, students' motivation comes from trying to please their teachers or to earn a good grade. The questions students must tackle are almost never generated by their own interest. Seven open-ended college algebra-level problems are presented in which the solution of one question suggests other related questions.…
School Desegregation: The Problem.
ERIC Educational Resources Information Center
Hill, Milton
In the process of school desegregation, many new and continuing problems have been illuminated. The problems fall into the general categories of interpersonal relations, communication between the races, new administrative arrangements, identification with the new schools and system rather than the former ones, inadequate instructional programs and…
Wicked Problems: Inescapable Wickedity
ERIC Educational Resources Information Center
Jordan, Michelle E.; Kleinsasser, Robert C.; Roe, Mary F.
2014-01-01
The article explores the concept of wicked problems and proposes a reinvigorated application of this concept for wider educational use. This recommendation stems from the contributions of a number of scholars who frame some of the most contentious and recalcitrant educational issues as wicked problems. The present authors build upon these previous…
ERIC Educational Resources Information Center
Thorson, Annette, Ed.
1999-01-01
This issue of ENC Focus focuses on the topic of inquiry and problem solving. Featured articles include: (1) "Inquiry in the Everyday World of Schools" (Ronald D. Anderson); (2) "In the Cascade Reservoir Restoration Project Students Tackle Real-World Problems" (Clint Kennedy with Advanced Biology Students from Cascade High School); (3) "Project…
ERIC Educational Resources Information Center
Davis, Pat
1997-01-01
Describes some problems of classroom dissection including the cruelty that animals destined for the laboratory suffer. Discusses the multilevel approach that the National Anti-Vivisection Society (NAVS) has developed to address the problems of animal dissection such as offering a dissection hotline, exhibiting at science teacher conferences, and…
Problems Facing Rural Schools.
ERIC Educational Resources Information Center
Stewart, C. E.; And Others
Problems facing rural Scottish schools range from short term consideration of daily operation to long term consideration of organizational alternatives. Addressed specifically, such problems include consideration of: (1) liaison between a secondary school and its feeder primary schools; (2) preservice teacher training for work in small, isolated…
ERIC Educational Resources Information Center
NatureScope, 1989
1989-01-01
Examines some of the reasons tropical rain forests are being destroyed and ways people are working to protect these forests. Provides activities on how people can help, reason for saving the forests, individual actions related to forest problems and solutions, and issues and problems. Three copyable pages accompany activities. (Author/RT)
ERIC Educational Resources Information Center
Cassidy, Jack
1991-01-01
Presents suggestions for teaching math word problems to elementary students. The strategies take into consideration differences between reading in math and reading in other areas. A problem-prediction game and four self-checking activities are included along with a magic password challenge. (SM)
PROBLEMS OF TURKISH LEXICOGRAPHY.
ERIC Educational Resources Information Center
TIETZE, ANDREAS
THE LEXICOGRAPHICAL PROBLEMS IN THE TURKISH LANGUAGE WERE DISCUSSED. HISTORICAL REVIEW OF THE LANGUAGE WAS PRESENTED WITH PROBLEMS OF LEXICOGRAPHY THAT EXISTED IN THE PAST COMPARED WITH THOSE OF THE PRESENT. DISCUSSION TOPICS OF THE REPORT INCLUDED (1) NAME OF THE LANGUAGE, (2) DELIMITATION COMPARED WITH RELATED LANGUAGES, (3) DELIMINATION…
A Stochastic Employment Problem
ERIC Educational Resources Information Center
Wu, Teng
2013-01-01
The Stochastic Employment Problem(SEP) is a variation of the Stochastic Assignment Problem which analyzes the scenario that one assigns balls into boxes. Balls arrive sequentially with each one having a binary vector X = (X[subscript 1], X[subscript 2],...,X[subscript n]) attached, with the interpretation being that if X[subscript i] = 1 the ball…
ERIC Educational Resources Information Center
MARTONFFY, ANDREA PONTECORVO; AND OTHERS
A CURRICULUM GUIDE IS PRESENTED FOR A 10-WEEK STUDY OF ANCIENT GREEK CIVILIZATION AT THE 10TH-GRADE LEVEL. TEACHING MATERIALS FOR THE UNIT INCLUDE (1) PRIMARY AND SECONDARY SOURCES DEALING WITH THE PERIOD FROM THE BRONZE AGE THROUGH THE HELLENISTIC PERIOD, (2) GEOGRAPHY PROBLEMS, AND (3) CULTURAL MODEL PROBLEM EXERCISES. THOSE CONCEPTS WITH WHICH…
Problems in baryon spectroscopy
Capstick, S.
1994-04-01
Current issues and problems in the physics of ground- and excited-state baryons are considered, and are classified into those which should be resolved by CEBAF in its present form, and those which may require CEBAF to undergo an energy upgrade to 8 GeV or more. Recent theoretical developments designed to address these problems are outlined.
ERIC Educational Resources Information Center
Allen, Deborah E.; Donham, Richard S.; Bernhardt, Stephen A.
2011-01-01
In problem-based learning (PBL), students working in collaborative groups learn by resolving complex, realistic problems under the guidance of faculty. There is some evidence of PBL effectiveness in medical school settings where it began, and there are numerous accounts of PBL implementation in various undergraduate contexts, replete with…
ERIC Educational Resources Information Center
STONE, EDWARD
THE REPORT POINTS OUT THAT, IN GENERAL, CHRONIC PROBLEM PARENTS GREW UP IN ENVIRONMENTS OF EMOTIONAL IMPOVERISHMENT, INCONSISTENCY, CONFUSION, AND DISORDER, OFTEN WITH DEPRIVATION OF FOOD, CLOTHING, AND SHELTER. THESE PARENTS CATEGORIZE PEOPLE AS THOSE WHO GIVE AND THOSE WHO TAKE. THEY BLAME THEIR PROBLEMS ON EXTERNAL CIRCUMSTANCES NOT UNDER THEIR…
Stabilization of Kepler's problem
NASA Technical Reports Server (NTRS)
Stokes, A.
1977-01-01
A regularization of Kepler's problem due to Moser (1970) is used to stabilize the equations of motion. In other words, a particular solution of Kepler's problem is imbedded in a Liapunov stable system. Perturbations can be introduced into the stabilized equations.
ERIC Educational Resources Information Center
Wheatley, Judy; Sudman, Rita Schmidt, Ed.
This packet of instructional materials is designed to give social science students in grades 6-9 a first-hand experience in working out solutions to real-life problems involving the management of California's water. Students work in groups on one of three problems presented in the packet: (1) the management of the Sacramento-San Joaquin Delta that…
The Guderley problem revisited
Ramsey, Scott D; Kamm, James R; Bolstad, John H
2009-01-01
The self-similar converging-diverging shock wave problem introduced by Guderley in 1942 has been the source of numerous investigations since its publication. In this paper, we review the simplifications and group invariance properties that lead to a self-similar formulation of this problem from the compressible flow equations for a polytropic gas. The complete solution to the self-similar problem reduces to two coupled nonlinear eigenvalue problems: the eigenvalue of the first is the so-called similarity exponent for the converging flow, and that of the second is a trajectory multiplier for the diverging regime. We provide a clear exposition concerning the reflected shock configuration. Additionally, we introduce a new approximation for the similarity exponent, which we compare with other estimates and numerically computed values. Lastly, we use the Guderley problem as the basis of a quantitative verification analysis of a cell-centered, finite volume, Eulerian compressible flow algorithm.
NASA Astrophysics Data System (ADS)
Singh, Chandralekha
2009-07-01
One finding of cognitive research is that people do not automatically acquire usable knowledge by spending lots of time on task. Because students' knowledge hierarchy is more fragmented, "knowledge chunks" are smaller than those of experts. The limited capacity of short term memory makes the cognitive load high during problem solving tasks, leaving few cognitive resources available for meta-cognition. The abstract nature of the laws of physics and the chain of reasoning required to draw meaningful inferences makes these issues critical. In order to help students, it is crucial to consider the difficulty of a problem from the perspective of students. We are developing and evaluating interactive problem-solving tutorials to help students in the introductory physics courses learn effective problem-solving strategies while solidifying physics concepts. The self-paced tutorials can provide guidance and support for a variety of problem solving techniques, and opportunity for knowledge and skill acquisition.
Generalized emissivity inverse problem.
Ming, DengMing; Wen, Tao; Dai, XianXi; Dai, JiXin; Evenson, William E
2002-04-01
Inverse problems have recently drawn considerable attention from the physics community due to of potential widespread applications [K. Chadan and P. C. Sabatier, Inverse Problems in Quantum Scattering Theory, 2nd ed. (Springer Verlag, Berlin, 1989)]. An inverse emissivity problem that determines the emissivity g(nu) from measurements of only the total radiated power J(T) has recently been studied [Tao Wen, DengMing Ming, Xianxi Dai, Jixin Dai, and William E. Evenson, Phys. Rev. E 63, 045601(R) (2001)]. In this paper, a new type of generalized emissivity and transmissivity inverse (GETI) problem is proposed. The present problem differs from our previous work on inverse problems by allowing the unknown (emissivity) function g(nu) to be temperature dependent as well as frequency dependent. Based on published experimental information, we have developed an exact solution formula for this GETI problem. A universal function set suggested for numerical calculation is shown to be robust, making this inversion method practical and convenient for realistic calculations.
NASA Technical Reports Server (NTRS)
1992-01-01
CBR Express software solves problems by adapting sorted solutions to new problems specified by a user. It is applicable to a wide range of situations. The technology was originally developed by Inference Corporation for Johnson Space Center's Advanced Software Development Workstation. The project focused on the reuse of software designs, and Inference used CBR as part of the ACCESS prototype software. The commercial CBR Express is used as a "help desk" for customer support, enabling reuse of existing information when necessary. It has been adopted by several companies, among them American Airlines, which uses it to solve reservation system software problems.
NASA Technical Reports Server (NTRS)
Lesso, W. G.; Kenyon, E.
1972-01-01
Consideration of the problems involved in choosing appropriate menus for astronauts carrying out SKYLAB missions lasting up to eight weeks. The problem of planning balanced menus on the basis of prepackaged food items within limitations on the intake of calories, protein, and certain elements is noted, as well as a number of other restrictions of both physical and arbitrary nature. The tailoring of a set of menus for each astronaut on the basis of subjective rankings of each food by the astronaut in terms of a 'measure of pleasure' is described, and a computer solution to this problem by means of a mixed integer programming code is presented.
Scheper, W A; Lobbezoo, F; Eijkman, M A J
2005-05-01
Divers can have several oral problems. Firstly, problems caused by pressure changes. These are barodontalgia and odontocrexis. Barodontalgia is toothache by barotrauma. Odontocrexis is restorations coming lose or breaking or tooth fractures by expansion of air beneath restorations. Other problems can occur by cements used to fix casted restorations, by inflammations in the orofacial region, and by not yet fully healed oral wounds. Secondly, there are problems related to the diver's mouthpiece. To keep the mouthpiece in place, the mandible has to be forced in a forward position. Holding this position often and for long periods of time, may develop or aggravate temporomandibular dysfunction. Insufficient fit of the mouthpiece may induce oral mucosal lesions. Therefore, it is recommended to produce individual diver mouthpieces. It is also recommended to produce individual diver mouthpieces for complete dentures wearing divers and for divers with fixed orthodontic appliances.
... the biggest health problem for people with diabetes. LDL cholesterol. LDL cholesterol is known as the bad cholesterol because it ... you often eat foods that are high in LDL cholesterol high cholesterol runs in your family HDL cholesterol. ...
ERIC Educational Resources Information Center
Carpenter, Thomas P.; And Others
1980-01-01
Student weaknesses on problem-solving portions of the NAEP mathematics assessment are discussed using Polya's heuristics as a framework. Recommendations for classroom instruction are discussed. (MP) Aspect of National Assessment (NAEP) dealt with in this document: Results (Interpretation).
ERIC Educational Resources Information Center
McDonald, James E.
1978-01-01
Several theories and treatments of enuresis are described. The authors conclude that enuresis is a social problem (perhaps due to maturational lag, developmental delay or faulty learning) which requires teacher and parental tolerance and understanding. (SE)
... too high. Over time, this can damage your eyes. The most common problem is diabetic retinopathy. It ... light-sensitive tissue at the back of your eye. You need a healthy retina to see clearly. ...
... words, whereas motor clumsiness or defective visual-spatial perception affects only handwriting, not spelling. Dyscalculia Dyscalculia is ... related to memory, problem solving skills, logical thought, perception and attention span. Like parents of other adolescents ...
... or legs? Yes Your symptoms may be from FIBROIDS, noncancerous tumors of the uterus. See your doctor. ... premature MENOPAUSE. Irregular periods may be due to FIBROIDS, HORMONE PROBLEMS, or other medical conditions. See your ...
ERIC Educational Resources Information Center
Bosch, Van Den Robert
1979-01-01
Contains a discussion of insects' ability to survive, of the development of pesticides and the introduction of DDT, of the problems of pesticide use and resistance to insecticides, and of the advantages of integrated pest control. (BB)
Overcoming breastfeeding problems
Plugged milk ducts; Nipple soreness when breastfeeding; Breastfeeding - overcoming problems; Let-down reflex ... oils can cause dry skin. Olive oil, expressed milk, and ointments containing lanolin can help soothe dry ...
NASA Technical Reports Server (NTRS)
Knight, Norman F., Jr.; Rankin, Charles C.
2006-01-01
This document summarizes the STructural Analysis of General Shells (STAGS) development effort, STAGS performance for selected demonstration problems, and STAGS application problems illustrating selected advanced features available in the STAGS Version 5.0. Each problem is discussed including selected background information and reference solutions when available. The modeling and solution approach for each problem is described and illustrated. Numerical results are presented and compared with reference solutions, test data, and/or results obtained from mesh refinement studies. These solutions provide an indication of the overall capabilities of the STAGS nonlinear finite element analysis tool and provide users with representative cases, including input files, to explore these capabilities that may then be tailored to other applications.
... less frequently than problems with smell. How Our Sense of Taste Works Our sense of taste, along ... may start to lose taste buds. Five Taste Sensations We can experience five basic taste sensations: sweet, ...
The cosmological constant problem
Dolgov, A.D.
1989-05-01
A review of the cosmological term problem is presented. Baby universe model and the compensating field model are discussed. The importance of more accurate data on the Hubble constant and the Universe age is stressed. 18 refs.
... orientation. This information is for people who have mouth (oral) problems related to HIV infection. It explains ... look like. It also describes where in the mouth they occur and how they are treated. They ...
ERIC Educational Resources Information Center
Wilson, James Q.; And Others
1972-01-01
Argues that most of the underlying assumptions of presently recommended solutions to the problem of heroin addiction are unreasonable, unwarranted, or at least open to more than one interpretation. (DM)
ERIC Educational Resources Information Center
Eperson, D. B.
1985-01-01
Presents six mathematical problems (with answers) which focus on: (1) chess moves; (2) patterned numbers; (3) quadratics with rational roots; (4) number puzzles; (5) Euclidean geometry; and (6) Carrollian word puzzles. (JN)
NASA Astrophysics Data System (ADS)
Amaral, Marcelo D.; Teixeira, Eduardo V.
2015-08-01
We study transmission problems with free interfaces from one random medium to another. Solutions are required to solve distinct partial differential equations, and , within their positive and negative sets respectively. A corresponding flux balance from one phase to another is also imposed. We establish existence and bounds of solutions. We also prove that variational solutions are non-degenerate and develop the regularity theory for solutions of such free boundary problems.
Sinn, H
1988-01-01
Problems concerning the provision of development aid to the Sahel region of Africa are discussed. The author argues that the population already exceeds the area's carrying capacity, and that the provision of direct aid to the region will only encourage further in-migration and exacerbate the problem. He argues that aid should be provided to neighboring areas with the capacity to support larger populations, which will eventually improve the standard of living of the whole region.
NASA Astrophysics Data System (ADS)
Schröer, H.
In basketball there is the problem of hitting a basket at a determined distance and a determined height. The quantities that can be changed during the inclined throw are the initial velocity and the angle of throw. At first we neglect the air resistance. Then we treat the same problem in a medium (liquid, gas) with constant density. We obtain two differential equations. Then we view special cases of the retarding force. There is an english and a german edition.
Smoothers for Optimization Problems
NASA Technical Reports Server (NTRS)
Arian, Eyal; Ta'asan, Shlomo
1996-01-01
We present a multigrid one-shot algorithm, and a smoothing analysis, for the numerical solution of optimal control problems which are governed by an elliptic PDE. The analysis provides a simple tool to determine a smoothing minimization process which is essential for multigrid application. Numerical results include optimal control of boundary data using different discretization schemes and an optimal shape design problem in 2D with Dirichlet boundary conditions.
NASA Technical Reports Server (NTRS)
Gejji, Raghvendra, R.
1992-01-01
Network transmission errors such as collisions, CRC errors, misalignment, etc. are statistical in nature. Although errors can vary randomly, a high level of errors does indicate specific network problems, e.g. equipment failure. In this project, we have studied the random nature of collisions theoretically as well as by gathering statistics, and established a numerical threshold above which a network problem is indicated with high probability.
The Guderley problem revisited
NASA Astrophysics Data System (ADS)
Ramsey, Scott D.; Kamm, James R.; Bolstad, John H.
2012-02-01
The self-similar converging-diverging shock wave problem introduced by Guderley in 1942 has been the source of considerable mathematical and physical interest. We investigate a novel application of the Guderley solution as a unique and challenging code verification test problem for compressible flow algorithms; this effort requires a unified understanding of the problem's mathematical and computational subtleties. Hence, we review the simplifications and group invariance properties that reduce the compressible flow equations for a polytropic gas to two coupled nonlinear eigenvalue problems: the first for the similarity exponent in the converging regime, and the second for a trajectory multiplier in the diverging regime. The information we provide, together with previously published material, gives a complete description of the computational steps required to construct a semi-analytic Guderley solution. We employ the problem in a quantitative code verification analysis of a cell-centred, finite volume, Eulerian compressible flow algorithm. Lastly, in appended material, we introduce a new approximation for the similarity exponent, which may prove useful in the future construction of certain semi-analytic Guderley solutions.
Bicriteria network design problems
Marathe, M.V.; Ravi, R.; Sundaram, R.; Ravi, S.S.; Rosenkrantz, D.J.; Hunt, H.B. III
1997-11-20
The authors study a general class of bicriteria network design problems. A generic problem in this class is as follows: Given an undirected graph and two minimization objectives (under different cost functions), with a budget specified on the first, find a subgraph from a given subgraph class that minimizes the second objective subject to the budget on the first. They consider three different criteria -- the total edge cost, the diameter and the maximum degree of the network. Here, they present the first polynomial-time approximation algorithms for a large class of bicriteria network design problems for the above mentioned criteria. The following general types of results are presented. First, they develop a framework for bicriteria problems and their approximations. Second, when the two criteria are the same they present a black box parametric search technique. This black box takes in as input an (approximation) algorithm for the criterion situation and generates an approximation algorithm for the bicriteria case with only a constant factor loss in the performance guarantee. Third, when the two criteria are the diameter and the total edge costs they use a cluster based approach to devise approximation algorithms. The solutions violate both the criteria by a logarithmic factor. Finally, for the class of treewidth-bounded graphs, they provide pseudopolynomial-time algorithms for a number of bicriteria problems using dynamic programming. The authors show how these pseudopolynomial-time algorithms can be converted to fully polynomial-time approximation schemes using a scaling technique.
Crystallographic image reconstruction problem
NASA Astrophysics Data System (ADS)
ten Eyck, Lynn F.
1993-11-01
The crystallographic X-ray diffraction experiment gives the amplitudes of the Fourier series expansion of the electron density distribution within the crystal. The 'phase problem' in crystallography is the determination of the phase angles of the Fourier coefficients required to calculate the Fourier synthesis and reveal the molecular structure. The magnitude of this task varies enormously as the size of the structures ranges from a few atoms to thousands of atoms, and the number of Fourier coefficients ranges from hundreds to hundreds of thousands. The issue is further complicated for large structures by limited resolution. This problem is solved for 'small' molecules (up to 200 atoms and a few thousand Fourier coefficients) by methods based on probabilistic models which depend on atomic resolution. These methods generally fail for larger structures such as proteins. The phase problem for protein molecules is generally solved either by laborious experimental methods or by exploiting known similarities to solved structures. Various direct methods have been attempted for very large structures over the past 15 years, with gradually improving results -- but so far no complete success. This paper reviews the features of the crystallographic image reconstruction problem which render it recalcitrant, and describes recent encouraging progress in the application of maximum entropy methods to this problem.
Preventing remediation problems
Fleming, W.H.
1994-12-31
Remediation, the design and construction of a remedy, typically represents the most significant portion of the cleanup process. The cost may be 5 to 10 times the cost of earlier investigation and feasibility efforts. Furthermore, the risks associated with remediation activities and their ability to meet ultimate cleanup goals and objectives are far greater than those associated with earlier efforts. Often times there are unrealistic expectations interjected throughout the design and construction process in the remediation field. The simple fact that most problems are buried, and one cannot see all that is below the ground surface provides sufficient uncertainty to result in problems. There are three key points during the remediation process which provide opportunities to prevent and avoid problems. These are: (1) during design; (2) during procurement and contracting; and (3) during construction. This paper examines actions which the author has found or believes will assist in providing a formula for success.
NASA Technical Reports Server (NTRS)
Harriss, R. C.
1980-01-01
Application of remote sensing techniques to the solution of geochemical problems is considered with emphasis on the 'carbon-cycle'. The problem of carbon dioxide sinks and the areal extent of coral reefs are treated. In order to assess the problems cited it is suggested that remote sensing techniques be utilized to: (1)monitor globally the carbonate and bicarbonate concentrations in surface waters of the world ocean; (2)monitor the freshwater and oceanic biomass and associated dissolved organic carbon; (3) inventory the coral reef areas and types and the associated oceanographic climatic conditions; and (4)measure the heavy metal fluxes from forested and vegetated areas, from volcanos, from different types of crustal rocks, from soils, and from sea surfaces.
Voge, V.M. )
1989-10-01
Freon 113 is not usually considered a toxic chemical and is not generally included in toxicology text lists of dangerous chemicals. However, during one 7-year period, the U.S. Navy recorded 38 freon-related mishaps, including 16 chemical burns and 22 inhalation injuries. Several deaths were also recorded. Part of the problem seems to be that freon compounds are excellent degreasing and cleaning agents. Consequently, they are widely and inappropriately used by aviation ground crews for this purpose. Such use usually presents no problem, except when the agent is used in small, closed, unventilated areas. This paper outlines the properties of freon that make it dangerous in the aviation community, some case histories of freon-related mishaps, what the Navy has done to control or prevent the problem from recurring, and the Navy's relative success with its prevention policies.
NASA Astrophysics Data System (ADS)
Izzo, Dario
2015-01-01
The orbital boundary value problem, also known as Lambert problem, is revisited. Building upon Lancaster and Blanchard approach, new relations are revealed and a new variable representing all problem classes, under L-similarity, is used to express the time of flight equation. In the new variable, the time of flight curves have two oblique asymptotes and they mostly appear to be conveniently approximated by piecewise continuous lines. We use and invert such a simple approximation to provide an efficient initial guess to an Householder iterative method that is then able to converge, for the single revolution case, in only two iterations. The resulting algorithm is compared, for single and multiple revolutions, to Gooding's procedure revealing to be numerically as accurate, while having a significantly smaller computational complexity.
Moran, B
2007-08-08
We present analytic solutions to two test problems that can be used to check the hydrodynamic implementation in computer codes designed to calculate the propagation of shocks in spherically convergent geometry. Our analysis is restricted to fluid materials with constant bulk modulus. In the first problem we present the exact initial acceleration and pressure gradient at the outer surface of a sphere subjected to an exponentially decaying pressure of the form P(t) = P{sub 0}e{sup -at}. We show that finely-zoned hydro-code simulations are in good agreement with our analytic solution. In the second problem we discuss the implosions of incompressible spherical fluid shells and we present the radial pressure profile across the shell thickness. We also discuss a semi-analytic solution to the time-evolution of a nearly spherical shell with arbitrary but small initial 3-dimensional (3-D) perturbations on its inner and outer surfaces.
The Anisotropic Kepler Problem
NASA Astrophysics Data System (ADS)
Broucke, R.
The author studies a version of the Kepler problem in the plane, where the constant of gravity G is assumed to have different values for the x-equation and the y-equation, in accordance with several previous studies by Gutzwiller, Devaney, Casasayas, Llibre and Belbruno. This problem is a somewhat unusual dynamical system because of several properties. The author first describes the different formulations and equations of motion that were used by different authors. He also discusses the properties of the collision manifold, following the approach of McGehee. This allows one to classify the flow near the origin.
MCNP: Neutron benchmark problems
Whalen, D.J.; Cardon, D.A.; Uhle, J.L.; Hendricks, J.S.
1991-11-01
The recent widespread and increased use of radiation transport codes has produced greater user and institutional demand for assurances that such codes give correct results. Responding to these requirements for code validation, the general purpose Monte Carlo transport code MCNP has been tested on criticality, pulsed sphere, and shielding neutron problem families. Results for each were compared to experimental data. MCNP successfully predicted the experimental results of all three families within the expected data and statistical uncertainties. These successful predictions demonstrate that MCNP can successfully model a broad spectrum of neutron transport problems. 18 refs., 27 figs., 4 tabs.
Moran, B
2005-06-02
We present test problems that can be used to check the hydrodynamic implementation in computer codes designed to model the implosion of a National Ignition Facility (NIF) capsule. The problems are simplified, yet one of them is three-dimensional. It consists of a nearly-spherical incompressible imploding shell subjected to an exponentially decaying pressure on its outer surface. We present a semi-analytic solution for the time-evolution of that shell with arbitrary small three-dimensional perturbations on its inner and outer surfaces. The perturbations on the shell surfaces are intended to model the imperfections that are created during capsule manufacturing.
Inverse heat conduction problems
NASA Astrophysics Data System (ADS)
Orlande, Helcio Rangel Barreto
We present the solution of the following inverse problems: (1) Inverse Problem of Estimating Interface Conductance Between Periodically Contacting Surfaces; (2) Inverse Problem of Estimating Interface Conductance During Solidification via Conjugate Gradient Method; (3) Determination of the Reaction Function in a Reaction-Diffusion Parabolic Problem; and (4) Simultaneous Estimation of Thermal Diffusivity and Relaxation Time with Hyperbolic Heat Conduction Model. Also, we present the solution of a direct problem entitled: Transient Thermal Constriction Resistance in a Finite Heat Flux Tube. The Conjugate Gradient Method with Adjoint Equation was used in chapters 1-3. The more general function estimation approach was treated in these chapters. In chapter 1, we solve the inverse problem of estimating the timewise variation of the interface conductance between periodically contacting solids, under quasi-steady-state conditions. The present method is found to be more accurate than the B-Spline approach for situations involving small periods, which are the most difficult on which to perform the inverse analysis. In chapter 2, we estimate the timewise variation of the interface conductance between casting and mold during the solidification of aluminum. The experimental apparatus used in this study is described. In chapter 3, we present the estimation of the reaction function in a one dimensional parabolic problem. A comparison of the present function estimation approach with the parameter estimation technique, wing B-Splines to approximate the reaction function, revealed that the use of function estimation reduces the computer time requirements. In chapter 4 we present a finite difference solution for the transient constriction resistance in a cylinder of finite length with a circular contact surface. A numerical grid generation scheme was used to concentrate grid points in the regions of high temperature gradients in order to reduce discretization errors. In chapter 6, we
Fung, Jimmy; Masser, Thomas; Morgan, Nathaniel R.
2012-06-25
The Sedov test is classically defined as a point blast problem. The Sedov problem has led us to advances in algorithms and in their understanding. Vorticity generation can be physical or numerical. Both play a role in Sedov calculations. The RAGE code (Eulerian) resolves the shock well, but produces vorticity. The source definition matters. For the FLAG code (Lagrange), CCH is superior to SGH by avoiding spurious vorticity generation. FLAG SGH currently has a number of options that improve results over traditional settings. Vorticity production, not shock capture, has driven the Sedov work. We are pursuing treatments with respect to the hydro discretization as well as to artificial viscosity.
Assessing the Quality of Problems in Problem-Based Learning
ERIC Educational Resources Information Center
Sockalingam, Nachamma; Rotgans, Jerome; Schmidt, Henk
2012-01-01
This study evaluated the construct validity and reliability of a newly devised 32-item problem quality rating scale intended to measure the quality of problems in problem-based learning. The rating scale measured the following five characteristics of problems: the extent to which the problem (1) leads to learning objectives, (2) is familiar, (3)…
Solving Common Mathematical Problems
NASA Technical Reports Server (NTRS)
Luz, Paul L.
2005-01-01
Mathematical Solutions Toolset is a collection of five software programs that rapidly solve some common mathematical problems. The programs consist of a set of Microsoft Excel worksheets. The programs provide for entry of input data and display of output data in a user-friendly, menu-driven format, and for automatic execution once the input data has been entered.
A Surprisingly Radical Problem
ERIC Educational Resources Information Center
Ledford, Sarah D.; Garner, Mary L.; Teachey, Angela L.
2012-01-01
Sometimes, in the teaching and learning of mathematics, open-ended problems posed by teachers or students can lead to a fuller understanding of mathematical concepts--a depth of understanding that no one could have anticipated. Interesting solutions and ideas emerged unexpectedly when the authors asked prospective and in-service teachers an "old"…
ERIC Educational Resources Information Center
Swinford, Ashleigh
2016-01-01
With rigor outlined in state and Common Core standards and the addition of constructed-response test items to most state tests, math constructed-response questions have become increasingly popular in today's classroom. Although constructed-response problems can present a challenge for students, they do offer a glimpse of students' learning through…
ERIC Educational Resources Information Center
Aznar, Mercedes Martinez; Orcajo, Teresa Ibanez
2005-01-01
A teaching unit on genetics and human inheritance using problem-solving methodology was undertaken with fourth-level Spanish Secondary Education students (15 year olds). The goal was to study certain aspects of the students' learning process (concepts, procedures and attitude) when using this methodology in the school environment. The change…
ERIC Educational Resources Information Center
Stanley, C. Maxwell
The book examines the historical background of and accomplishments in seven global problem areas. It is hypothesized that effective management within today's framework is the only way to progress toward the political and economic order that is necessary to assure peace and security, justice, and human rights, and to improve the quality of life. It…
ERIC Educational Resources Information Center
Huntsman, Jeffrey F.
The problems confronting the translator of American Indian literature are immense. The history of European Indian relations has obscured many original Indian values and attitudes and has substituted a set of simplistic and unreal Anglo attitudes that translators must transcend. Unlike most Western literature, Indian literature does not instruct,…
[Nutrition and andrological problems].
Calcamuggi, G; Marcarino, C; Emanuelli, G
1991-12-01
Andrologic problems were considered as nutrition is concerned: vitamin and oligo-element deficiencies, metabolic alterations, and toxic intake. Ethanol role was examined and discussed for its relevance in psychological and organic impairment due to both chronic abuse and acute intake, mainly for its role on hypothalamic-pituitary-gonadal axis. Rational nutrition is a clue in sexual disturbance prevention, correction and integrated care.
Punishment: Problems in Definition.
ERIC Educational Resources Information Center
Myers, Carmel
This paper examines the problems in definition of punishment at the construct level, comparing the common use meaning of the term with a behavioral definition and contrasting two definitions used within the field of psychology. The paper discusses whether punishing stimuli must be physically painful, the appropriate use of painful stimuli, and…
ERIC Educational Resources Information Center
Hanson, Deroy L.
Designed to motivate eighth-grade civics students in the study of the United States Constitution, this game is intended to simulate the basic problems faced by the delegates to the Philadelphia Convention of 1787. The four parts of the game introduce the governmental concepts of the bicameral legislature, the executive branch, the judicial branch,…
ERIC Educational Resources Information Center
De Bono, Edward
A group of children were presented with several tasks, including the invention of a sleep machine and a machine to weigh elephants. The tasks were chosen to involve the children in coping with problems of a distinct character. A study of the children's drawings and interpretations shows that children's thinking ability is not very different from…
Universal Design Problem Solving
ERIC Educational Resources Information Center
Sterling, Mary C.
2004-01-01
Universal design is made up of four elements: accessibility, adaptability, aesthetics, and affordability. This article addresses the concept of universal design problem solving through experiential learning for an interior design studio course in postsecondary education. Students' experiences with clients over age 55 promoted an understanding of…
ERIC Educational Resources Information Center
Brown, Marion, Comp.; And Others
This document presents guidelines for handling disruptive behavior in the Schenectady County Public Library (New York). Specific responses are listed for dealing with questions about library selection policy and sudden patron illness or injury. Also listed are responses to problem situations involving angry or irate patrons, assault or physically…
Chemical Reaction Problem Solving.
ERIC Educational Resources Information Center
Veal, William
1999-01-01
Discusses the role of chemical-equation problem solving in helping students predict reaction products. Methods for helping students learn this process must be taught to students and future teachers by using pedagogical skills within the content of chemistry. Emphasizes that solving chemical reactions should involve creative cognition where…
Managing soil remediation problems.
Okx, J P; Hordijk, L; Stein, A
1996-12-01
Soil remediation has only a short history but the problem addressed is a significant one. Cost estimates for the clean-up of contaminated sites in the European Union and the United States are in the order of magnitude of 1,400 billion ECU. Such an enormous operation deserves the best management it can get. Reliable cost estimations per contaminated site are an important prerequisite. This paper addresses the problems related to site-wise estimations.When solving soil remediation problems, we have to deal with a large number of scientific disciplines. Too often solutions are presented from the viewpoint of only one discipline. In order to benefit from the combined disciplinary knowledge and experience, we think that it is necessary to describe the interrelations between these disciplines. This can be realized by developing an adequate model of the desired process which enables to consider and evaluate the essential factors as interdependent components of the total system.The resulting model provides a binding paradigm to the contributing disciplines which will result in improved efficiency and effectivity of the decision and the cost estimation process. In the near future, we will release the "Biosparging and Bioventing Expert Support System", an expert support system for problem owners, consultants and authorities dealing with the design and operation of a biosparging and/or a bioventing system.
Bicriteria network design problems
Marathe, M.V.; Ravi, R.; Sundaram, R.; Ravi, S.S.; Rosenkrantz, D.J.; Hunt, H.B. III
1995-05-01
We study several bicriteria network design problems phrased as follows: given an indirected graph and two minimization objectives with a budget specified on one objective, find a subgraph satisfying certain connectivity requirements that minimizes the second objective subject to the budget on the first. First, we develop a formalism for bicriteria problems and their approximations. Secondly, we use a simple parametric search technique to provide bicriteria approximation algorithms for problems with two similar criteria, where both criteria are the same measure (such as the diameter or the total cost of a tree) but differ only in the cost function under which the measure is computed. Thirdly, we present an (O(log n), O(log n))-approximation algorithm for finding a diameter-constrained minimum cost spanning tree of an undirected graph on n nodes. Finally, for the class of treewidth-bounded graphs, we provide pseudopolynomial-time algorithms for a number of bicriteria problems using dynamic programming. These pseudopolynomial-time algorithms can be converted to fully polynomial-time approximation schemes using a scaling technique.
ERIC Educational Resources Information Center
Moore, Jerilou; Sumrall, William J.
2008-01-01
Exploring our patent system is a great way to engage students in creative problem solving. As a result, the authors designed a teaching unit that uses the study of patents to explore one avenue in which scientists and engineers do science. Specifically, through the development of an idea, students learn how science and technology are connected.…
ERIC Educational Resources Information Center
Holden, Becky
2007-01-01
Seeking more effective mathematics instruction, this author decided to incorporate Cognitively Guided Instruction (CGI) into first-grade classroom lessons. Students in CGI mathematics classrooms are prompted to use their prior knowledge to solve new problems, establish cognitive structures to which new learning can be connected, and be driven by…
ERIC Educational Resources Information Center
Cook, Martin
1995-01-01
Students studying water as a class project were concerned by levels of pollution at a nearby river and the local beach. They identified three environmental problems for research including sewage discharge, beach litter, and quality of swimming water. Research consisted of field trips which allowed for opportunities to improve skills in collecting…
Problems in Graduate Education...
ERIC Educational Resources Information Center
Whaley, W. Gordon
The Commission on Graduate Education of the National Association of State Universities and Land Grant Colleges has assembled in this booklet the nature of the fundamental problems of graduate education accompanied by recommendations for action. Nine areas of concern include redesigning graduate education for the twentieth century, distinguishing…
Emery, V.J.; Kivelson, S.A.
1993-12-31
In the past few years there has been a resurgence of interest in dynamical impurity problems, as a result of developments in the theory of correlated electron systems. The general dynamical impurity problem is a set of conduction electrons interacting with an impurity which has internal degrees of freedom. The simplest and earliest example, the Kondo problem, has attracted interest since the mid-sixties not only because of its physical importance but also as an example of a model displaying logarithmic divergences order by order in perturbation theory. It provided one of the earliest applications of the renormalization group method, which is designed to deal with just such a situation. As we shall see, the antiferromagnetic Kondo model is controlled by a strong-coupling fixed point, and the essence of the renormalization group solution is to carry out the global renormalization numerically starting from the original (weak-coupling) Hamiltonian. In these lectures, we shall describe an alternative route in which we identify an exactly solvable model which renormalizes to the same fixed point as the original dynamical impurity problem. This approach is akin to determining the critical behavior at a second order phase transition point by solving any model in a given universality class.
ERIC Educational Resources Information Center
Emmel, Thomas C.; Sligh, Michael M.
1970-01-01
Asserts that overpopulation is the most pressing world problem. Topics discussed include population control in primitive societies, population growth and control in modern societies, methods of motivational population control, consequences of no population control, and mass famines during the 1970's in underdeveloped countries. Cities 33…
Solving Problems through Circles
ERIC Educational Resources Information Center
Grahamslaw, Laura; Henson, Lisa H.
2015-01-01
Several problem-solving interventions that utilise a "circle" approach have been applied within the field of educational psychology, for example, Circle Time, Circle of Friends, Sharing Circles, Circle of Adults and Solution Circles. This research explored two interventions, Solution Circles and Circle of Adults, and used thematic…
and Internalizing Behavior Problems
ERIC Educational Resources Information Center
Hofer, Claire; Eisenberg, Nancy; Spinrad, Tracy L.; Morris, Amanda S.; Gershoff, Elizabeth; Valiente, Carlos; Kupfer, Anne; Eggum, Natalie D.
2013-01-01
Stability and change in mother-adolescent conflict reactions (CRs) and the prediction of CRs from adolescents' earlier behavior problems (and vice versa) were examined with 131 mothers and their adolescents (63 boys). Dyads engaged in a 6-min conflict discussion twice, 2 years apart ["M" age was 13 at Time 1 (T1)]. Non-verbal expressive and verbal…
LEXICOGRAPHICAL PROBLEMS IN PASHTO.
ERIC Educational Resources Information Center
CHAVARRIS-AGUILAR, O.L.; PENZL, HERBERT
PROBLEMS IN DEVELOPING SUITABLE DICTIONARIES OF PASHTO WERE REPORTED. PASHTO WAS DESCRIBED AS A MEMBER OF THE IRANIAN BRANCH OF THE INDO-EUROPEAN LANGUAGES SPOKEN IN EASTERN AND SOUTHERN AFGHANISTAN AND IN NORTHEASTERN PAKISTAN. FIVE TOPICS DEALING WITH THE PASHTO LANGUAGE WERE DISCUSSED--(1) STATISTICS, (2) WRITTEN CORPUS AND LEXICAL STUDIES, (3)…
"Righting" the Writing Problem.
ERIC Educational Resources Information Center
Shaughnessy, Michael F.; Eastham, Nicholas
The problem of college students' writing skills or lack thereof is generally agreed upon in academia. One cause is the inordinate amount of multiple choice/true false/fill in the blank type of tests that students take in high school and college. Not only is there is a dearth of actual classes in writing available, few students recognize the need…
Environmental Health Problems.
ERIC Educational Resources Information Center
Environmental Health Service (DHEW/PHS), Rockville, MD.
Aimed at a society which is forced to make decisions relative to their total environment, this pamphlet discusses a few of the problems associated with restoring and maintaining an environmental relationship conducive to the health and well-being of man. The topics covered include: air pollution, noise, solid waste, the urban environment, drinking…
Avoid programmable controller problems
DeVries, E.A.
1983-06-01
This article illustrates good hardware installation practices and careful software documentation to help minimize PC problems and aid troubleshooting. Presents a typical ladder diagram, a binary logic diagram, a typical computer generated cross-reference list, an assignment list, and a cross-reference sheet.
Circumference and Problem Solving.
ERIC Educational Resources Information Center
Blackburn, Katie; White, David
The concept of pi is one of great importance to all developed civilization and one that can be explored and mastered by elementary students through an inductive and problem-solving approach. Such an approach is outlined and discussed. The approach involves the following biblical quotation: "And he made a moltin sea ten cubits from one brim to the…
Unlocking the Latchkey Problem.
ERIC Educational Resources Information Center
Press-Dawson, Andee
1987-01-01
"Kids-on-Campus" provides before and after school child care services in partnership with seven school districts in Sacramento and Yolo Counties (CA). It is the ideal solution to the latchkey children problem with the program taking responsibility for all the development and administration of in-school child care programs. (MD)
ERIC Educational Resources Information Center
Nelson, Norman N.; Fisch, Forest N.
1973-01-01
Discussed are techniques of presentation and solution of the Classical Cake Problem. A frosted cake with a square base is to be cut into n pieces with the volume of cake and frosting the same for each piece. Needed are minimal geometric concepts and the formula for the volume of a prism. (JP)
Introspection in Problem Solving
ERIC Educational Resources Information Center
Jäkel, Frank; Schreiber, Cornell
2013-01-01
Problem solving research has encountered an impasse. Since the seminal work of Newell und Simon (1972) researchers do not seem to have made much theoretical progress (Batchelder and Alexander, 2012; Ohlsson, 2012). In this paper we argue that one factor that is holding back the field is the widespread rejection of introspection among cognitive…
ERIC Educational Resources Information Center
Crick, Francis; Koch, Christof
1992-01-01
Discusses approaches to the problem presented in understanding consciousness as a yet undiscovered process of interacting neuron activity. Presents the historical context of research in the area of human awareness and identifies research necessary to scientifically explain how the brain relates to the mind. (MCO)
NASA Technical Reports Server (NTRS)
Douglas, G.
1972-01-01
The problems of excess capacity in the airline industry are discussed with focus on the following topics: load factors; fair rate of return on investment; service-quality rivalry among airlines; pricing (fare) policies; aircraft production; and the impacts of excess capacity on operating costs. Also included is a discussion of the interrelationships among these topics.
ERIC Educational Resources Information Center
Hoyer, William J.; And Others
1975-01-01
Many of the clinically disabling behaviors of elderly persons may be viewed as operants. Research bearing on the efficacy of operant techniques for programming individualized, group based, and ward-wide therapeutic intervention is reviewed. Suggests the operant view is useful for conceptualizing and treating many problem behaviors of elderly…
ERIC Educational Resources Information Center
Wisconsin Univ. - Stout, Menomonie. Center for Vocational, Technical and Adult Education.
The teacher directed problem solving activities package contains 17 units: Future Community Design, Let's Build an Elevator, Let's Construct a Catapult, Let's Design a Recreational Game, Let's Make a Hand Fishing Reel, Let's Make a Wall Hanging, Let's Make a Yo-Yo, Marooned in the Past, Metrication, Mousetrap Vehicles, The Multi System…
ERIC Educational Resources Information Center
Currier, Sarah Cox
2015-01-01
In this article, Sarah Currier, a math specialist at Elizabeth Hall International School in Minnesota, describes how she used origami in a deliberate manner to teach content. She shares how she uses paper folding to teach mathematical concepts, reinforce vocabulary, and as a problem-solving model. She also offers ideas for using origami in other…
A Multifaceted Minimization Problem.
ERIC Educational Resources Information Center
Pomeranz, Janet Bellcourt
1983-01-01
The problem "Given three planar points, find a point such that the sum of the distances from that point to the three points is a minimum" is discussed from several points of view. A solution that uses only calculus and geometry is examined in detail. (MNS)
Buffon's Coin Problem and beyond
ERIC Educational Resources Information Center
Schneiter, Kady
2011-01-01
This article describes an investigation of Buffon's coin problem and related problems with the aid of an applet. The problems are accessible at a variety of grade levels and facilitate making connections between geometry and probability.
Gravitational Many-Body Problem
Makino, J.
2008-04-29
In this paper, we briefly review some aspects of the gravitational many-body problem, which is one of the oldest problems in the modern mathematical science. Then we review our GRAPE project to design computers specialized to this problem.
NASA Technical Reports Server (NTRS)
1979-01-01
The corrosion problem, it turned out, stemmed from the process called electrolysis. When two different metals are in contact, an electrical potential is set up between them; when the metals are surrounded by an electrolyte, or a conducting medium, the resulting reaction causes corrosion, often very rapid corrosion. In this case the different metals were the copper grounding system and the ferry's aluminum hull; the dockside salt water in which the hull was resting served as the electrolyte. After identifying the source of the trouble, the Ames engineer provided a solution: a new wire-and-rod grounding system made of aluminum like the ferry's hull so there would no longer be dissimilar metals in contact. Ames research on the matter disclosed that the problem was not unique to the Golden Gate ferries. It is being experienced by many pleasure boat operators who are probably as puzzled about it as was the Golden Gate Transit Authority.
Scattering problems in elastodynamics
NASA Astrophysics Data System (ADS)
Diatta, Andre; Kadic, Muamer; Wegener, Martin; Guenneau, Sebastien
2016-09-01
In electromagnetism, acoustics, and quantum mechanics, scattering problems can routinely be solved numerically by virtue of perfectly matched layers (PMLs) at simulation domain boundaries. Unfortunately, the same has not been possible for general elastodynamic wave problems in continuum mechanics. In this Rapid Communication, we introduce a corresponding scattered-field formulation for the Navier equation. We derive PMLs based on complex-valued coordinate transformations leading to Cosserat elasticity-tensor distributions not obeying the minor symmetries. These layers are shown to work in two dimensions, for all polarizations, and all directions. By adaptative choice of the decay length, the deep subwavelength PMLs can be used all the way to the quasistatic regime. As demanding examples, we study the effectiveness of cylindrical elastodynamic cloaks of the Cosserat type and approximations thereof.
FBST for Cointegration Problems
NASA Astrophysics Data System (ADS)
Diniz, M.; Pereira, C. A. B.; Stern, J. M.
2008-11-01
In order to estimate causal relations, the time series econometrics has to be aware of spurious correlation, a problem first mentioned by Yule [21]. To solve the problem, one can work with differenced series or use multivariate models like VAR or VEC models. In this case, the analysed series are going to present a long run relation i.e. a cointegration relation. Even though the Bayesian literature about inference on VAR/VEC models is quite advanced, Bauwens et al. [2] highlight that "the topic of selecting the cointegrating rank has not yet given very useful and convincing results." This paper presents the Full Bayesian Significance Test applied to cointegration rank selection tests in multivariate (VAR/VEC) time series models and shows how to implement it using available in the literature and simulated data sets. A standard non-informative prior is assumed.
Dermatologic problems in amputees.
DesGroseilliers, J P; DesJardins, J P; Germain, J P; Krol, A L
1978-03-01
Improvements in surgical techniques and prosthetic devices and the establishment of prosthetic clinics have altered the outlook for the amputee. A cooperative effect on the part of professionals looking after amputee patients, as carried out in these clinics, offers the best means of recognition and treatment of difficulties as they arise. Until the "bionic man" becomes a reality, amputees will continue to have skin problems. In describing a number of illustrative cases, we have attempted to: (a) renew interest in these problems; (b) demonstrate the value of the group approach; and (c) encourage the participation of interested dermatologists in the prosthetic clinic team to facilitate earlier recognition and treatment of troublesome skin disorders in the amputee.
Dermatologic problems in amputees.
DesGroseilliers, J. P.; DesJardins, J. P.; Germain, J. P.; Krol, A. L.
1978-01-01
Improvements in surgical techniques and prosthetic devices and the establishment of prosthetic clinics have altered the outlook for the amputee. A cooperative effect on the part of professionals looking after amputee patients, as carried out in these clinics, offers the best means of recognition and treatment of difficulties as they arise. Until the "bionic man" becomes a reality, amputees will continue to have skin problems. In describing a number of illustrative cases, we have attempted to: (a) renew interest in these problems; (b) demonstrate the value of the group approach; and (c) encourage the participation of interested dermatologists in the prosthetic clinic team to facilitate earlier recognition and treatment of troublesome skin disorders in the amputee. Images FIG. 1 FIG. 2 PMID:630514
Modern problems of thermodynamics
NASA Astrophysics Data System (ADS)
Novikov, I. I.
2012-12-01
The role of energy and methods of its saving for the development of human society and life are analyzed. The importance of future use of space energy flows and energy of water and air oceans is emphasized. The authors consider the idea of the unit for production of electric energy and pure substances using sodium chloride which reserves are limitless on the planet. Looking retrospectively at the development of power engineering from the elementary fire to modern electric power station, we see that the used method of heat production, namely by direct interaction of fuel and oxidizer, is the simplest. However, it may be possible to combust coal, i.e., carbon in salt melt, for instance, sodium chloride that would be more rational and efficient. If the stated problems are solved positively, we would master all energy properties of the substance; and this is the main problem of thermodynamics being one of the sciences on energy.
Haykin, Simon; Chen, Zhe
2005-09-01
This review presents an overview of a challenging problem in auditory perception, the cocktail party phenomenon, the delineation of which goes back to a classic paper by Cherry in 1953. In this review, we address the following issues: (1) human auditory scene analysis, which is a general process carried out by the auditory system of a human listener; (2) insight into auditory perception, which is derived from Marr's vision theory; (3) computational auditory scene analysis, which focuses on specific approaches aimed at solving the machine cocktail party problem; (4) active audition, the proposal for which is motivated by analogy with active vision, and (5) discussion of brain theory and independent component analysis, on the one hand, and correlative neural firing, on the other.
Beaver, B V
1986-12-01
Accurate diagnosis of the cause of aggression in horses is essential to determining the appropriate course of action. The affective forms of aggression include fear-induced, pain-induced, intermale, dominance, protective, maternal, learned, and redirected aggressions. Non-affective aggression includes play and sex-related forms. Irritable aggression and hypertestosteronism in mares are medical problems, whereas genetic factors, brain dysfunction, and self-mutilation are also concerns. PMID:3492250
NASA Technical Reports Server (NTRS)
Bourke, Roger D.
1982-01-01
Energy management in its most comprehensive sense encompasses economic, technical, environmental, and political problems. The present evaluation of prospects notes that opportunities for energy conservation are widespread, in such fields as building air conditioning, transportation, electrical appliances, and industrial processes. Further conservation is expected to be achieved through a combination of technology development and economics; the latter factor must not be unduly influenced by political measures that shield consumers from the true cost of energy.
Working on interesting problems
NASA Astrophysics Data System (ADS)
Smith, Arfon M.
2015-01-01
BSc Chemistry, The University of Sheffield 2001... PhD Astrochemistry, The University of Nottingham 2006... Scientist at GitHub Inc. 2013.From the outside, the path an individual has taken from academia to industry is not an obvious one. In this session I'll (try and) explain how an interest in software, engineering and chasing interesting problems makes internet startup in San Francisco a great home.
NASA Technical Reports Server (NTRS)
Dikshit, Piyush; Guimaraes, Katia; Ramamurthy, Maya; Agrawala, Ashok K.; Larsen, Ronald L.
1989-01-01
In a previous work we have defined a general architecture model for autonomous systems, which can be mapped easily to describe the functions of any automated system (SDAG-86-01). In this note, we use the model to describe the problem of thermal management in space stations. First we briefly review the architecture, then we present the environment of our application, and finally we detail the specific function for each functional block of the architecture for that environment.
High Altitude Medical Problems
Hultgren, Herbert N.
1979-01-01
Increased travel to high altitude areas by mountaineers and nonclimbing tourists has emphasized the clinical problems associated with rapid ascent. Acute mountain sickness affects most sojourners at elevations above 10,000 feet. Symptoms are usually worse on the second or third day after arrival. Gradual ascent, spending one to three days at an intermediate altitude, and the use of acetazolamide (Diamox) will prevent or ameliorate symptoms in most instances. Serious and potentially fatal problems, such as high altitude pulmonary edema or cerebral edema, occur in approximately 0.5 percent to 1.0 percent of visitors to elevations above 10,000 feet—especially with heavy physical exertion on arrival, such as climbing or skiing. Early recognition, high flow oxygen therapy and prompt descent are crucially important in management. Our knowledge of the causes of these and other high altitude problems, such as retinal hemorrhage, systemic edema and pulmonary hypertension, is still incomplete. Even less is known of the effect of high altitudes on medical conditions common at sea level or on the action of commonly used drugs. ImagesFigure 2. PMID:483805
Medical problems of musicians.
Lockwood, A H
1989-01-26
Surveys of performing musicians indicate that almost half of them experience playing-related medical problems, some of which threaten or end their careers. Overuse injuries involving the muscle--tendon unit are the most common problem, with symptoms ranging from mild pain while the musician is playing to pain severe enough to preclude any use of the affected hand. String players are the most commonly affected, and percussionists the least. The most important predisposing characteristic is the use of repetitive movements during long hours of practice, but awkward body positions mandated by the shape and weight of the instrument, the technical difficulty of the repertoire, and unfamiliar instruments may also play a part. Women are more commonly affected than men. Rest is the cornerstone of therapy. Neural impingement syndromes affecting the median or ulnar nerves or the thoracic outlet affect many musicians. Focal dystonias may involve part or all of a hand or the muscles forming the embouchure (the position of the lips in wind players). These are very resistant to therapy and may terminate or drastically alter a career. Stress, especially performance anxiety, may impede performance. Beta-adrenergic blocking agents prevent the symptoms of performance anxiety and are frequently used by musicians without medical supervision. A recognition of the unique problems of musician-patients has led to the formation of successful specialty clinics in a number of cities. PMID:2643048
NASA Astrophysics Data System (ADS)
Ruskey, Frank; Williams, Aaron
In the classic Josephus problem, elements 1, 2,...,n are placed in order around a circle and a skip value k is chosen. The problem proceeds in n rounds, where each round consists of traveling around the circle from the current position, and selecting the kth remaining element to be eliminated from the circle. After n rounds, every element is eliminated. Special attention is given to the last surviving element, denote it by j. We generalize this popular problem by introducing a uniform number of lives ℓ, so that elements are not eliminated until they have been selected for the ℓth time. We prove two main results: 1) When n and k are fixed, then j is constant for all values of ℓ larger than the nth Fibonacci number. In other words, the last surviving element stabilizes with respect to increasing the number of lives. 2) When n and j are fixed, then there exists a value of k that allows j to be the last survivor simultaneously for all values of ℓ. In other words, certain skip values ensure that a given position is the last survivor, regardless of the number of lives. For the first result we give an algorithm for determining j (and the entire sequence of selections) that uses O(n 2) arithmetic operations.
Wang, Mao-Che; Liu, Chia-Yu; Shiao, An-Suey; Wang, Tyrone
2005-08-01
Acute diffuse otitis externa (swimmer's ear), otomycosis, exostoses, traumatic eardrum perforation, middle ear infection, and barotraumas of the inner ear are common problems in swimmers and people engaged in aqua activities. The most common ear problem in swimmers is acute diffuse otitis externa, with Pseudomonas aeruginosa being the most common pathogen. The symptoms are itching, otalgia, otorrhea, and conductive hearing loss. The treatment includes frequent cleansing of the ear canal, pain control, oral or topical medications, acidification of the ear canal, and control of predisposing factors. Swimming in polluted waters and ear-canal cleaning with cotton-tip applicators should be avoided. Exostoses are usually seen in people who swim in cold water and present with symptoms of accumulated debris, otorrhea and conductive hearing loss. The treatment for exostoses is transmeatal surgical removal of the tumors. Traumatic eardrum perforations may occur during water skiing or scuba diving and present with symptoms of hearing loss, otalgia, otorrhea, tinnitus and vertigo. Tympanoplasty might be needed if the perforations do not heal spontaneously. Patients with chronic otitis media with active drainage should avoid swimming, while patients who have undergone mastoidectomy and who have no cavity problems may swim. For children with ventilation tubes, surface swimming is safe in a clean, chlorinated swimming pool. Sudden sensorineural hearing loss and some degree of vertigo may occur after diving because of rupture of the round or oval window membrane.
Adolescent Temperament: Childhood Problem Precursors and Problem Behavior Correlates.
ERIC Educational Resources Information Center
Windle, Michael
Interrelations between childhood behavior problems and adolescent temperament, and between adolescent temperament and problem behaviors, were studied. A sample of 311 adolescents with an average age of 15.7 years completed self-report measures regarding behavior problems before age 13, temperament, alcohol consumption, alcohol-related problems,…
Problem-Framing: A perspective on environmental problem-solving
NASA Astrophysics Data System (ADS)
Bardwell, Lisa V.
1991-09-01
The specter of environmental calamity calls for the best efforts of an involved public. Ironically, the way people understand the issues all too often serves to discourage and frustrate rather than motivate them to action. This article draws from problem-solving perspectives offered by cognitive psychology and conflict management to examine a framework for thinking about environmental problems that promises to help rather than hinder efforts to address them. Problem-framing emphasizes focusing on the problem definition. Since how one defines a problem determines one's understanding of and approach to that problem, being able to redefine or reframe a problem and to explore the “problem space” can help broaden the range of alternatives and solutions examined. Problem-framing incorporates a cognitive perspective on how people respond to information. It explains why an emphasis on problem definition is not part of people's typical approach to problems. It recognizes the importance of structure and of having ways to organize that information on one's problem-solving effort. Finally, problem-framing draws on both cognitive psychology and conflict management for strategies to manage information and to create a problem-solving environment that not only encourages participation but can yield better approaches to our environmental problems.
Space Power Engineering Problems
NASA Astrophysics Data System (ADS)
Senkevich, V. P.
2002-01-01
Development of space power engineering in the first half of XXI century shall be aimed at preventing the forthcoming energy crisis and ecological catastrophes. The problem can be solved through using solar energy being perpetual, endless, and ecologically safe. As of now, issues on the development and employment of solar power stations and its beaming to the ground stations in the SHF band are put on the agenda. The most pressing problem is to develop orbital solar reflectors to illuminate towns in the polar regions, agricultural regions, and areas of processing sea products. Space-based technologies can be used to deal with typhoons, green house effects, and "ozone holes". Recently, large, frameless film structures formed by centrifugal forces offer the promise of structures for orbital power plants, reflectors, and solar sails. A big success is achieved in the development of power generating solar array elements of amorphous silicon. These innovations would make the development of orbital solar power plants dozens of times cheaper. Such solar arrays shall be used in the nearest future on heavy communication satellites and the Earth remote sensing platforms for generation of 140-160 kW at a specific power beyond 300 W/kg. The cargo traffic needed to develop and maintain the orbital power plants and reflector systems could be equipped with solar sails as the future low thrust propulsion. In 2000, the mankind witnessed an unexpected beginning of energy crisis along with strong hydro- meteorological events (typhoons, floods) that shocked the USA, the Western Europe, England, Japan, and other countries. The total damage is estimated as 90 billions of dollars. The mankind is approaching a boundary beyond which its further existence would depend on how people would learn to control weather and use ecologically safe power sources. Space technology base on the research potential accumulated in the previous century could serve for the solution of this problem.
Irrelevance in Problem Solving
NASA Technical Reports Server (NTRS)
Levy, Alon Y.
1992-01-01
The notion of irrelevance underlies many different works in AI, such as detecting redundant facts, creating abstraction hierarchies and reformulation and modeling physical devices. However, in order to design problem solvers that exploit the notion of irrelevance, either by automatically detecting irrelevance or by being given knowledge about irrelevance, a formal treatment of the notion is required. In this paper we present a general framework for analyzing irrelevance. We discuss several properties of irrelevance and show how they vary in a space of definitions outlined by the framework. We show how irrelevance claims can be used to justify the creation of abstractions thereby suggesting a new view on the work on abstraction.
Rowatt, R.J.
1993-01-01
Post-consumer plastic is a symptom of the municipal solid waste (MSW) problem, not the cause. Yet the U.S. public sees plastic as a major contributor to the waste stream. Two-thirds say the environmental risks of using plastics outweigh the benefits and that they favor mandatory recycling programs in their community; more than four-fifths think recycling can substantially reduce the amount of solid waste and decry the presence of nonbiodegradable plastics in landfills. Given this perception, the author reviews solid waste management issues and examines the contributions that resin producers can make.
Mechanics: Ideas, problems, applications
NASA Astrophysics Data System (ADS)
Ishlinskii, A. Iu.
The book contains the published articles and reports by academician Ishlinskii which deal with the concepts and ideas of modern mechanics, its role in providing a general understanding of the natural phenomena, and its applications to various problems in science and engineering. Attention is given to the methodological aspects of mechanics, to the history of the theories of plasticity, friction, gyroscopic and inertial systems, and inertial navigation, and to mathematical methods in mechanics. The book also contains essays on some famous scientists and engineers.
Cohen, May
1977-01-01
While patients frequently make it difficult for us to uncover their sexual concerns, a much greater difficulty is due to physicians' unwillingness to deal with this subject. Physicians need to acquire basic knowledge about human sexuality as well as skills in making patients feel comfortable and open. A non-judgmental attitude is essential. The physician will also be able to anticipate and prevent sexual distress by education. Expertise must be developed in differentiating those problems requiring referral for specialized sexual counselling from those which the family physician can handle. PMID:21304865
Billinge, S.
2010-03-22
Diffraction techniques are making progress in tackling the difficult problem of solving the structures of nanoparticles and nanoscale materials. The great gift of x-ray crystallography has made us almost complacent in our ability to locate the three-dimensional coordinates of atoms in a crystal with a precision of around 10{sup -4} nm. However, the powerful methods of crystallography break down for structures in which order only extends over a few nanometers. In fact, as we near the one hundred year mark since the birth of crystallography, we face a resilient frontier in condensed matter physics: our inability to routinely and robustly determine the structure of complex nanostructured and amorphous materials. Knowing the structure and arrangement of atoms in a solid is so fundamental to understanding its properties that the topic routinely occupies the early chapters of every solid-state physics textbook. Yet what has become clear with the emergence of nanotechnology is that diffraction data alone may not be enough to uniquely solve the structure of nanomaterials. As part of a growing effort to incorporate the results of other techniques to constrain x-ray refinements - a method called 'complex modeling' which is a simple but elegant approach for combining information from spectroscopy with diffraction data to solve the structure of several amorphous and nanostructured materials. Crystallography just works, so we rarely question how and why this is so, yet understanding the physics of diffraction can be very helpful as we consider the nanostructure problem. The relationship between the electron density distribution in three dimensions (i.e., the crystal structure) and an x-ray diffraction pattern is well established: the measured intensity distribution in reciprocal space is the square of the Fourier transform of the autocorrelation function <{rho}(r){rho}(r+r')> of the electron density distribution {rho}(r). The fact that we get the autocorrelation function
Problem Order Implications for Learning
ERIC Educational Resources Information Center
Li, Nan; Cohen, William W.; Koedinger, Kenneth R.
2013-01-01
The order of problems presented to students is an important variable that affects learning effectiveness. Previous studies have shown that solving problems in a blocked order, in which all problems of one type are completed before the student is switched to the next problem type, results in less effective performance than does solving the problems…
Problem Solving in the Professions.
ERIC Educational Resources Information Center
Jackling, Noel; And Others
1990-01-01
It is proposed that algorithms and heuristics are useful in improving professional problem-solving abilities when contextualized within the academic discipline. A basic algorithm applied to problem solving in undergraduate engineering education and a similar algorithm applicable to legal problems are used as examples. Problem complexity and…
Model for assessing psychosocial problems.
Tannenbaum, D.; McGillivray, M.
1996-01-01
The Model for the Assessment of Psychosocial Problems (MAPP) can help family medicine residents effectively assess patients with psychosocial problems. Following a patient-centred clinical method, MAPP provides a guide to exploring problems and an approach that allows residents and patients jointly to define problems and decide upon management. Emphasis is placed on clarifying patients' expectations of physicians. PMID:9222578
ERIC Educational Resources Information Center
Chin, Christine; Chia, Li-Gek
2008-01-01
One way of implementing project-based science (PBS) is to use problem-based learning (PBL), in which students formulate their own problems. These problems are often ill-structured, mirroring complex real-life problems where data are often messy and inclusive. In this article, the authors describe how they used PBL in a ninth-grade biology class in…
Design Problems for Secondary Students
ERIC Educational Resources Information Center
Jonassen, David H.
2011-01-01
Are there different kinds of design problems? Jonassen (2011) argued that problems vary in terms of structuredness, complexity, and context. On the structuredness and complexity continua, design problems tend to be the most ill-structured and complex. Brown and Chandrasekaran suggest that design problems may vary along a continuum from…
Inman, Verne T.; Barnes, Gilbert H.; Levy, S. William; Loon, Henry E.; Ralston, H. J.
1961-01-01
The initial trauma of a major amputation and the medical disorders secondary to it are being studied at the Biomechanics Laboratory. Problems that arise from amputation and from the replacement of the limb by a prosthetic device are complex but interrelated, and approaches to study on basic, applied and clinical levels must be integrated. Three studies carried on at the Biomechanics Laboratory are described in this paper. In the field of amputation operations, it is believed that certain osteoplastic and myoplastic techniques, along with protection for nerve stumps and measures to provide optimum circulatory conditions, may restore biological and mechanical function to a greater degree than is possible with present procedures. From studies of the expenditure of energy during locomotion with and without assistive devices and during therapeutic exercise, it was found that crutch-walking is metabolically much more costly in energy for the amputee than walking with the suction-socket prosthesis; through these studies, it will be possible to define criteria for maximum work loads for disabled persons. In dermatological studies, although there are still unsolved problems, successful methods of treatment have been developed for certain bacterial and fungus infections, contact dermatitides and disorders resulting from edema. ImagesFigure 1.Figure 2.Figure 3.Figure 4.Figure 5.Figure 6.Figure 7. PMID:13717754
A statistical mechanical problem?
Costa, Tommaso; Ferraro, Mario
2014-01-01
The problem of deriving the processes of perception and cognition or the modes of behavior from states of the brain appears to be unsolvable in view of the huge numbers of elements involved. However, neural activities are not random, nor independent, but constrained to form spatio-temporal patterns, and thanks to these restrictions, which in turn are due to connections among neurons, the problem can at least be approached. The situation is similar to what happens in large physical ensembles, where global behaviors are derived by microscopic properties. Despite the obvious differences between neural and physical systems a statistical mechanics approach is almost inescapable, since dynamics of the brain as a whole are clearly determined by the outputs of single neurons. In this paper it will be shown how, starting from very simple systems, connectivity engenders levels of increasing complexity in the functions of the brain depending on specific constraints. Correspondingly levels of explanations must take into account the fundamental role of constraints and assign at each level proper model structures and variables, that, on one hand, emerge from outputs of the lower levels, and yet are specific, in that they ignore irrelevant details. PMID:25228891
PSYCHOSOMATIC PROBLEMS IN UROLOGY
Auerback, Alfred; Smith, Donald R.
1952-01-01
The intimate relationship between the urinary and genital systems permits stimuli in one system to influence the other. At least 15 per cent of women with symptoms of cystitis have no organic basis for their complaints. In psychiatric studies it has been noted that sexual conflict is the primary etiological factor in these patients. In some cases, continuance of the disorder leads to irreversible organic change. Urinary symptoms such as frequency, urgency, burning or retention are most common in women and become an automatic response to anxiety-provoking or sexual stimuli. In men, functional urinary symptoms are relatively infrequent. Often they indicate problems of genital dysfunction. Complaints of impotence, penile pain, testicular pain, or non-specific urethritis stem back to difficulties in their sexual lives. Many of the patients have symptoms of a generalized anxiety tension state due to sexual problems. A purely organic consideration of genitourinary disorders will lead to erroneous conclusions and unsatisfactory therapeutic results. The psychosomatic approach—that is, considering both physical and psychological aspects—will explain many hitherto difficult cases. PMID:14886756
Abstraction and Problem Reformulation
NASA Technical Reports Server (NTRS)
Giunchiglia, Fausto
1992-01-01
In work done jointly with Toby Walsh, the author has provided a sound theoretical foundation to the process of reasoning with abstraction (GW90c, GWS9, GW9Ob, GW90a). The notion of abstraction formalized in this work can be informally described as: (property 1), the process of mapping a representation of a problem, called (following historical convention (Sac74)) the 'ground' representation, onto a new representation, called the 'abstract' representation, which, (property 2) helps deal with the problem in the original search space by preserving certain desirable properties and (property 3) is simpler to handle as it is constructed from the ground representation by "throwing away details". One desirable property preserved by an abstraction is provability; often there is a relationship between provability in the ground representation and provability in the abstract representation. Another can be deduction or, possibly inconsistency. By 'throwing away details' we usually mean that the problem is described in a language with a smaller search space (for instance a propositional language or a language without variables) in which formulae of the abstract representation are obtained from the formulae of the ground representation by the use of some terminating rewriting technique. Often we require that the use of abstraction results in more efficient .reasoning. However, it might simply increase the number of facts asserted (eg. by allowing, in practice, the exploration of deeper search spaces or by implementing some form of learning). Among all abstractions, three very important classes have been identified. They relate the set of facts provable in the ground space to those provable in the abstract space. We call: TI abstractions all those abstractions where the abstractions of all the provable facts of the ground space are provable in the abstract space; TD abstractions all those abstractions wllere the 'unabstractions' of all the provable facts of the abstract space are
ERIC Educational Resources Information Center
Math Forum @ Drexel, 2009
2009-01-01
Different techniques for understanding a problem can lead to ideas for never-used-before solutions. Good problem-solvers use a problem-solving strategy and may come back to it frequently while they are working on the problem to refine their strategy, see if they can find better solutions, or find other questions. Writing is an integral part of…
A genetic uncertainty problem.
Tautz, D
2000-11-01
The existence of genes that, when knocked out, result in no obvious phenotype has puzzled biologists for many years. The phenomenon is often ascribed to redundancy in regulatory networks, caused by duplicated genes. However, a recent systematic analysis of data from the yeast genome projects does not support a link between gene duplications and redundancies. An alternative explanation suggests that genes might also evolve by very weak selection, which would mean that their true function cannot be studied in normal laboratory experiments. This problem is comparable to Heisenberg's uncertainty relationship in physics. It is possible to formulate an analogous relationship for biology, which, at its extreme, predicts that the understanding of the full function of a gene might require experiments on an evolutionary scale, involving the entire effective population size of a given species.
Edmondson, Amy C
2016-06-01
Companies today increasingly rely on teams that span many industries for radical innovation, especially to solve "wicked problems." So leaders have to understand how to promote collaboration when roles are uncertain, goals are shifting, expertise and organizational cultures are varied, and participants have clashing or even antagonistic perspectives. HBS professor Amy Edmondson has studied more than a dozen cross-industry innovation projects, among them the creation of a new city, a mango supply-chain transformation, and the design and construction of leading-edge buildings. She has identified the leadership practices that make successful cross-industry teams work: fostering an adaptable vision, promoting psychological safety, enabling knowledge sharing, and encouraging collaborative innovation. Though these practices are broadly familiar, their application within cross-industry teams calls for unique leadership approaches that combine flexibility, open-mindedness, humility, and fierce resolve. PMID:27491195
Instrumentation problems for physicians.
Turner, G O
1980-01-01
The physician has, for whatever reasons, diminished his or her level of involvement on the team dedicated to developing, refining, and evaluating medical technology. As a result, the challenge confronting the physician and the technology development team today is to orchestrate a team structure that will ensure the greatest input and commitment from physicians and other professionals during current and future technology development. The charges of cost escalation and dehumanization in our system of health care delivery will also be discussed, as will the lack of, or confusion about, access to data concerning cost of a given instrument, and fuzzy semantics and perspectives on technology and instrumentation. The author suggests answers to, or means to ameliorate, the problems.
The Inhibiting Bisection Problem
Pinar, Ali; Fogel, Yonatan; Lesieutre, Bernard
2006-12-18
Given a graph where each vertex is assigned a generation orconsumption volume, we try to bisect the graph so that each part has asignificant generation/consumption mismatch, and the cutsize of thebisection is small. Our motivation comes from the vulnerability analysisof distribution systems such as the electric power system. We show thatthe constrained version of the problem, where we place either the cutsizeor the mismatch significance as a constraint and optimize the other, isNP-complete, and provide an integer programming formulation. We alsopropose an alternative relaxed formulation, which can trade-off betweenthe two objectives and show that the alternative formulation of theproblem can be solved in polynomial time by a maximum flow solver. Ourexperiments with benchmark electric power systems validate theeffectiveness of our methods.
Naqvi, Hassan R; Mathur, Shawn; Covarrubias, David; Curcio, Josephine A; Schmidt, Christian
2008-01-01
Convictions are a driving force for actions. Considering that every individual has a different set of convictions and larger groups act once a consensus decision is reached, one can see that debate is an inherent exercise in decision-making. This requires a sustainably generated surplus to allow time for intellectual exchange, gathering of information and dissemination of findings. It is essential that the full spectrum of options remain treated equally. At the end of this process, a choice has to be made. Looking back at a later time point, a retrospective analysis sometimes reveals that the choice was neither completely free nor a truly conscious one. Leaving the issue of consequences of a once made decision aside, we wish to contribute to the debate of the problem of choice. PMID:19025607
Edmondson, Amy C
2016-06-01
Companies today increasingly rely on teams that span many industries for radical innovation, especially to solve "wicked problems." So leaders have to understand how to promote collaboration when roles are uncertain, goals are shifting, expertise and organizational cultures are varied, and participants have clashing or even antagonistic perspectives. HBS professor Amy Edmondson has studied more than a dozen cross-industry innovation projects, among them the creation of a new city, a mango supply-chain transformation, and the design and construction of leading-edge buildings. She has identified the leadership practices that make successful cross-industry teams work: fostering an adaptable vision, promoting psychological safety, enabling knowledge sharing, and encouraging collaborative innovation. Though these practices are broadly familiar, their application within cross-industry teams calls for unique leadership approaches that combine flexibility, open-mindedness, humility, and fierce resolve.
NASA Astrophysics Data System (ADS)
Mauroy, Alexandre; Taslakian, Perouz; Langerman, Stefan; Jungers, Raphaël
2016-09-01
A four-bar linkage is a mechanism consisting of four rigid bars which are joined by their endpoints in a polygonal chain and which can rotate freely at the joints (or vertices). We assume that the linkage lies in the 2-dimensional plane so that one of the bars is held horizontally fixed. In this paper we consider the problem of reconfiguring a four-bar linkage using an operation called a pop. Given a four-bar linkage, a pop reflects a vertex across the line defined by its two adjacent vertices along the polygonal chain. Our main result shows that for certain conditions on the lengths of the bars, the neighborhood of any configuration that can be reached by smooth motion can also be reached by pops. The proof relies on the fact that pops are described by a map on the circle with an irrational number of rotation.
The Microchp Scheduling Problem
NASA Astrophysics Data System (ADS)
Bosman, M. G. C.; Bakker, V.; Molderink, A.; Hurink, J. L.; Smit, G. J. M.
2009-08-01
The increasing penetration of renewable energy sources, the demand for more energy efficient electricity production and the increase in distributed electricity generation causes a shift in the way electricity is produced and consumed. The downside of these changes in the electricity grid is that network stability and controllability becomes more difficult compared to the old situation. The new network has to accommodate various means of production, consumption and buffering and needs to offer control over the energy flows between these three elements. In order to offer such a control mechanism we need to know more about the individual aspects. In this paper we focus on the modelling of distributed production. Especially we look at the use of microCHP (Combined Heat and Power) appliances in a group of houses. The problem of planning the production runs of the microCHP is modelled via an ILP formulation both for a single house and for a group of houses.
NASA Astrophysics Data System (ADS)
Huerta, Dora; Ruiz-Suarez, Jesus
2004-03-01
The segregation of large intruders in a vertically vibrated granular bed is studied. We measure rising times a function of density, diameter and depth; for two different sinusoidal excitations. Our results shed definitive light to explain the fundamental aspects of the fascinating Brazil nut problem. At low frequencies (high amplitudes), inertia and convection are the only mechanisms behind segregation. Inertia dominates when the relative density of the intruder is greater than one and convection when it is less than one. At high frequencies (small amplitudes), where convection is suppressed, segregation occurs by buoyancy or sinkage. Finally, when the diameter of the intruders is changed, the well known paradigm "larger intruders rise faster" fails if the mass of the intruders is kept constant (while their relative densities are greater than one).
[Hypersomnia: a diagnostic problem].
Kranenburg, Guido; Teunissen, Laurien L
2014-01-01
Hypersomnia is a frequently occurring problem. When taking a medical history it is important to distinguish between fatigue and sleepiness. We present a 14-year-old girl with narcolepsy and a 59-year-old man with idiopathic hypersomnia. Features that are typical of narcolepsy are cataplexy and weight gain. Features that are typical of both narcolepsy and idiopathic hypersomnia are daytime naps, insomnia, sleep paralysis and hypnagogic hallucinations. Additional testing in patients with hypersomnia should include a polysomnography in order to exclude other sleeping disorders, and a mean sleep latency test. Practice shows that both patients with narcolepsy and those with idiopathic hypersomnia benefit from treatment with stimulating drugs such as modafinil. PMID:25096034
The worldwide "wildfire" problem.
Gill, A Malcolm; Stephens, Scott L; Cary, Geoffrey J
2013-03-01
The worldwide "wildfire" problem is headlined by the loss of human lives and homes, but it applies generally to any adverse effects of unplanned fires, as events or regimes, on a wide range of environmental, social, and economic assets. The problem is complex and contingent, requiring continual attention to the changing circumstances of stakeholders, landscapes, and ecosystems; it occurs at a variety of temporal and spatial scales. Minimizing adverse outcomes involves controlling fires and fire regimes, increasing the resistance of assets to fires, locating or relocating assets away from the path of fires, and, as a probability of adverse impacts often remains, assisting recovery in the short-term while promoting the adaptation of societies in the long-term. There are short- and long-term aspects to each aspect of minimization. Controlling fires and fire regimes may involve fire suppression and fuel treatments such as prescribed burning or non-fire treatments but also addresses issues associated with unwanted fire starts like arson. Increasing the resistance of assets can mean addressing the design and construction materials of a house or the use of personal protective equipment. Locating or relocating assets can mean leaving an area about to be impacted by fire or choosing a suitable place to live; it can also mean the planning of land use. Assisting recovery and promoting adaptation can involve insuring assets and sharing responsibility for preparedness for an event. There is no single, simple, solution. Perverse outcomes can occur. The number of minimizing techniques used, and the breadth and depth of their application, depends on the geographic mix of asset types. Premises for policy consideration are presented. PMID:23634593
Kolkata Restaurant Problem as a Generalised El Farol Bar Problem
NASA Astrophysics Data System (ADS)
Chakrabarti, Bikas K.
Generalisation of the El Farol bar problem to that of many bars here leads to the Kolkata restaurant problem, where the decision to go to any restaurant or not is much simpler (depending on the previous experience of course, as in the El Farol bar problem). This generalised problem can be exactly analysed in some limiting cases discussed here. The fluctuation in the restaurant service can be shown to have precisely an inverse cubic behavior, as widely seen in the stock market fluctuations.
Computer Problem-Solving Coaches
NASA Astrophysics Data System (ADS)
Hsu, Leon; Heller, Kenneth
2005-09-01
Computers might be able to play an important role in physics instruction by coaching students to develop good problem-solving skills. Building on previous research on student problem solving and on designing computer programs to teach cognitive skills, we are developing a prototype computer coach to provide students with guided practice in solving problems. In addition to helping students become better problem solvers, such programs can be useful in studying how students learn to solve problems and how and if problem-solving skills can be transferred from a computer to a pencil-and-paper environment.
Addressing problems of employee performance.
McConnell, Charles R
2011-01-01
Employee performance problems are essentially of 2 kinds: those that are motivational in origin and those resulting from skill deficiencies. Both kinds of problems are the province of the department manager. Performance problems differ from problems of conduct in that traditional disciplinary processes ordinarily do not apply. Rather, performance problems are addressed through educational and remedial processes. The manager has a basic responsibility in ensuring that everything reasonable is done to help each employee succeed. There are a number of steps the manager can take to address employee performance problems.
Developing Metacognitive and Problem-Solving Skills through Problem Manipulation
ERIC Educational Resources Information Center
Parker Siburt, Claire J.; Bissell, Ahrash N.; Macphail, Richard A.
2011-01-01
In a collaborative effort between the our university's department of chemistry and the academic resource center, we designed a model for general chemistry recitation based on a problem manipulation method in which students actively assess the skills and knowledge used to answer a chemical problem and then manipulate the problem to create a new…
Problem Solvers: Problem--How Long Can You Stand?
ERIC Educational Resources Information Center
Teaching Children Mathematics, 2010
2010-01-01
Healthy lifestyles are increasingly emphasized these days. This month the authors begin a series of mathematical problems that also address physical activity. They hope that these problems offer opportunities to investigate mathematics and also reinforce the desire to lead a healthy life. In their first problem of the academic year, students…
Problem Formulation and Resolution in Online Problem-Based Learning
ERIC Educational Resources Information Center
Kenny, Richard F.; Bullen, Mark; Loftus, Jay
2006-01-01
This paper discusses an exploratory study to investigate the existence, and nature, of student problem formulation and resolution processes in an undergraduate online Problem-Based Learning (PBL) course in Agricultural Sciences. We report on the use of a content analysis instrument developed to measure problem formulation and resolution (PFR)…
Problem Solving through an Optimization Problem in Geometry
ERIC Educational Resources Information Center
Poon, Kin Keung; Wong, Hang-Chi
2011-01-01
This article adapts the problem-solving model developed by Polya to investigate and give an innovative approach to discuss and solve an optimization problem in geometry: the Regiomontanus Problem and its application to football. Various mathematical tools, such as calculus, inequality and the properties of circles, are used to explore and reflect…
Adolescent Problem Behavior and Problem Driving in Young Adulthood
ERIC Educational Resources Information Center
Bingham, C. Raymond; Shope, Jean T.
2004-01-01
Motor vehicle crashes are the leading cause of death among drivers younger than age 35, making problem driving behavior among young drivers a significant public concern. Effective intervention requires a better understanding of the antecedents of problem driving. Problem behavior theory, social control theory, and Kandel's model of substance use…
Energy Problems and Environmental Concern
ERIC Educational Resources Information Center
Train, Russell E.
1973-01-01
Discusses problems encountered in energy extraction and consumption, involving nuclear power plant construction, environmental consequences of energy systems, and energy conservation ethics. Indicates that the increasing concern over environmental quality is not the true cause of present energy problems. (CC)
Strengthening Programs through Problem Solving.
ERIC Educational Resources Information Center
Dyer, Jim
1993-01-01
Describes a secondary agricultural education program that was a dumping ground for academically disadvantaged students. Discusses how such a program can be improved by identifying problems and symptoms, treating problems, and goal setting. (JOW)
Dental Health and Orthodontic Problems
... Text Size Email Print Share Dental Health and Orthodontic Problems Page Content Article Body Dental Health Twin ... color can be tinted to match the teeth. Orthodontic Problems Crooked teeth, overbites and underbites are best ...
Decision Analysis for Environmental Problems
Environmental management problems are often complex and uncertain. A formal process with proper guidance is needed to understand the issues, identify sources of disagreement, and analyze the major uncertainties in environmental problems. This course will present a process that fo...
Sherlock Holmes, Master Problem Solver.
ERIC Educational Resources Information Center
Ballew, Hunter
1994-01-01
Shows the connections between Sherlock Holmes's investigative methods and mathematical problem solving, including observations, characteristics of the problem solver, importance of data, questioning the obvious, learning from experience, learning from errors, and indirect proof. (MKR)
Dementia - behavior and sleep problems
... gov/ency/patientinstructions/000029.htm Dementia - behavior and sleep problems To use the sharing features on this ... sleep and stay asleep Tips for Behavior and Sleep Problems Having a daily routine may help. Calmly ...
Analyzing and Solving Productivity Problems.
ERIC Educational Resources Information Center
Walsh, David S.; Johnson, Thomas J.
1980-01-01
The authors discuss ways to define a company's position on productivity, and explain productivity concepts. They describe a problem cause/solution set matrix with which to identify accurately the most probable cause of productivity problems. (SK)
The Problem of Defining Intelligence.
ERIC Educational Resources Information Center
Lubar, David
1981-01-01
The major philosophical issues surrounding the concept of intelligence are reviewed with respect to the problems surrounding the process of defining and developing artificial intelligence (AI) in computers. Various current definitions and problems with these definitions are presented. (MP)
Community Providers’ Views of Alcohol Problems and Drug Problems
Gassman, Ruth A.; Weisner, Constance
2013-01-01
This study contrasts community health and social service providers’ views on alcohol vs. other drug abuse. A probability sample of 457 social work and other providers from a county’s public and private medical and mental health clinics, welfare and criminal justice systems, and substance abuse programs, as well as clergy, private therapists, and physicians were interviewed. For both alcohol and drug problems, providers thought only of severe dysfunctions, which suggest that less severe forms of these problems may evade detection. In addition, drug problems were viewed as more harmful than alcohol problems, which may result in providers minimizing alcohol problems. PMID:23565054
Enhancing chemistry problem-solving achievement using problem categorization
NASA Astrophysics Data System (ADS)
Bunce, Diane M.; Gabel, Dorothy L.; Samuel, John V.
The enhancement of chemistry students' skill in problem solving through problem categorization is the focus of this study. Twenty-four students in a freshman chemistry course for health professionals are taught how to solve problems using the explicit method of problem solving (EMPS) (Bunce & Heikkinen, 1986). The EMPS is an organized approach to problem analysis which includes encoding the information given in a problem (Given, Asked For), relating this to what is already in long-term memory (Recall), and planning a solution (Overall Plan) before a mathematical solution is attempted. In addition to the EMPS training, treatment students receive three 40-minute sessions following achievement tests in which they are taught how to categorize problems. Control students use this time to review the EMPS solutions of test questions. Although problem categorization is involved in one section of the EMPS (Recall), treatment students who received specific training in problem categorization demonstrate significantly higher achievement on combination problems (those problems requiring the use of more than one chemical topic for their solution) at (p = 0.01) than their counterparts. Significantly higher achievement for treatment students is also measured on an unannounced test (p = 0.02). Analysis of interview transcripts of both treatment and control students illustrates a Rolodex approach to problem solving employed by all students in this study. The Rolodex approach involves organizing equations used to solve problems on mental index cards and flipping through them, matching units given when a new problem is to be solved. A second phenomenon observed during student interviews is the absence of a link in the conceptual understanding of the chemical concepts involved in a problem and the problem-solving skills employed to correctly solve problems. This study shows that explicit training in categorization skills and the EMPS can lead to higher achievement in complex problem
Inverse Problems of Thermoelectricity
NASA Astrophysics Data System (ADS)
Anatychuk, L. I.; Luste, O. J.; Kuz, R. V.; Strutinsky, M. N.
2011-05-01
Classical thermoelectricity is based on the use of the Seebeck and Thomson effects that occur in the near-contact areas between n- and p-type materials. A conceptually different approach to thermoelectric power converter design that is based on the law of thermoelectric induction of currents is also known. The efficiency of this approach has already been demonstrated by its first applications. More than 10 basically new types of thermoelements were discovered with properties that cannot be achieved by thermocouple power converters. Therefore, further development of this concept is of practical interest. This paper provides a classification and theory for solving the inverse problems of thermoelectricity that form the basis for devising new thermoelement types. Computer methods for their solution for anisotropic and inhomogeneous media are elaborated. Regularities related to thermoelectric current excitation in anisotropic and inhomogeneous media are established. The possibility of obtaining eddy currents of a particular configuration through control of the temperature field and material parameters for the creation of new thermo- element types is demonstrated for three-dimensional (3D) models of anisotropic and inhomogeneous media.
NASA Astrophysics Data System (ADS)
Crameri, Reto; Burkart, Werner
The importance of the radon problem is illustrated by the fact that the indoor exposure to radon and radon daughters amounts to about 40% of the total effective dose equivalent to which the population is exposed to both, from natural and man made sources. This exposure may increase even further due to new building technologies optimized for energy conservation. Although radon and its decay products are well known to cause lung cancer at high exposure levels, considerable controversy remains about the magnitude of risk due to low-level exposure. Linear extrapolation from the dose-response values of uranium miners who were heavily exposed to these nuclides would suggest that a relevant fraction (10-40%) of lung cancers in the general population are caused by the inhalation of radon daughters. Moreover, the results of monitoring programs in several countries during the past years have revealed that for a small, but not negligible fraction of the population, the lifetime exposure from indoor radon daughters is comparable to, or even exceeds the occupational radon exposure of moderately exposed underground miners still showing a significant excess lung cancer frequency.
Postdatism -- a perinatal problem?
Chhabra, S; Sood, S
1990-01-01
It has been traditionally accepted that maternal and fetal complications are at their lowest levels 37-42 weeks into gestation. 20% of pregnancies completed after 42 weeks gestation are thought to be affected by the postmaturity syndrome of uteroplacental insufficiency resulting in oligohydramnios, meconium passage, loss of fetal subcutaneous tissue, fetal asphyxia, and fetal death. Some workers, however, have also found that pregnancies completed between 40 and 42 weeks carry significant risk. The authors explored this question in a case-control study of 464 women seen at the Mahatma Gandhi Institute of Medical Sciences in Maharashtra, India. The cases of postdatism occurred in the absence of any other medical or obstetric problem. The operative delivery rate increased significantly among these patients compared to deliveries between 39 and 40 weeks. There was neither significant asphyxia nor perinatal loss in term completed normal patients. Asphyxia and perinatal mortality did, however, occur with postdatism. The authors note the likely role of oligohydramnios combined with placental dysfunction.
Large Spectral Library Problem
Chilton, Lawrence K.; Walsh, Stephen J.
2008-10-03
Hyperspectral imaging produces a spectrum or vector at each image pixel. These spectra can be used to identify materials present in the image. In some cases, spectral libraries representing atmospheric chemicals or ground materials are available. The challenge is to determine if any of the library chemicals or materials exist in the hyperspectral image. The number of spectra in these libraries can be very large, far exceeding the number of spectral channels collected in the ¯eld. Suppose an image pixel contains a mixture of p spectra from the library. Is it possible to uniquely identify these p spectra? We address this question in this paper and refer to it as the Large Spectral Library (LSL) problem. We show how to determine if unique identi¯cation is possible for any given library. We also show that if p is small compared to the number of spectral channels, it is very likely that unique identi¯cation is possible. We show that unique identi¯cation becomes less likely as p increases.
Identifying and managing problem drinkers.
Kahan, M.
1996-01-01
Problem drinking is far more common than severe alcohol dependence and is associated with considerable morbidity and health care costs. Whereas patients with alcohol dependence respond best to intensive treatment, one or more brief sessions of physician advice and counseling reduces alcohol consumption among problem drinkers. The two most useful tools to identify problem drinkers are the CAGE and the drinking problem question. PMID:8653034
Smoothing of mixed complementarity problems
Gabriel, S.A.; More, J.J.
1995-09-01
The authors introduce a smoothing approach to the mixed complementarity problem, and study the limiting behavior of a path defined by approximate minimizers of a nonlinear least squares problem. The main result guarantees that, under a mild regularity condition, limit points of the iterates are solutions to the mixed complementarity problem. The analysis is applicable to a wide variety of algorithms suitable for large-scale mixed complementarity problems.
The lawnmower problem and other geometric path covering problems
Fekete, S.; Arkin, E.; Mitchell, J.
1994-12-31
We discuss the Lawnmower Problem: Given a polygonal region, find the shortest closed path along which we have to move a given object (typically a square or a circle), such that any point of the region will be covered by the object for some position of it movement. In another version of the problem, known as the Milling Problem, the object has to stay within the region at all times. Practical motivations for considering the Lawnmower Problem come from manufacturing (spray painting, quality control), geography (aerial surveys), optimization (tour planning for a large number of clients with limited mobility), and gardening. The Milling Problem has gained attention by its importance for NC pocket machining. We show that both problems are NP-hard and discuss approximation methods for various versions of the problem.
Problem Solving Skills for Children.
ERIC Educational Resources Information Center
Youngs, Bettie B.
This guide was written for children, to help them handle problems they might encounter, learn about other children and how they have handled similar problems, and learn what to do when things go wrong or when they feel misunderstood. In the introduction, children are assured that, even when they have problems, they can be happy again. The body of…
Problem Analysis: Challenging All Learners
ERIC Educational Resources Information Center
Garcia, Katie; Davis, Alicia
2013-01-01
In this article, Garcia and Davis describe problem analysis as the process of examining a given mathematics exercise to find ways in which the problem can be modified and extended to create a richer learning opportunity for students. Students are often reluctant to attempt what they perceive to be higher-order thinking problems, but problem…
Problem Solving and Beginning Programming.
ERIC Educational Resources Information Center
McAllister, Alan
Based on current models of problem solving within cognitive psychology, this study focused on the spontaneous problem solving strategies used by children as they first learned LOGO computer programming, and on strategy transformations that took place during the problem solving process. The research consisted of a six weeks programming training…
Crustal growth: Some major problems
NASA Technical Reports Server (NTRS)
Arculus, R. J.
1988-01-01
Fundamental problems with models currently used to explain the genesis and evolution of continental crust were raised. These problems focus around the difficulty of generating the upper continental crust from a lower crustal or mantle protolith without leaving a very large, and so far undetected, volume of restite. No conclusive resolution to the problems was achieved.
ERIC Educational Resources Information Center
Wild, Walter J.
1980-01-01
Discusses the simplest three-body problem, known as Euler's problem. The article, intended for students in the undergraduate mathematics and physics curricula, shows how the complex equations for a specific three-body problem can be solved on a small calculator. (HM)
Supporting Problem Solving in PBL
ERIC Educational Resources Information Center
Jonassen, David
2011-01-01
Although the characteristics of PBL (problem focused, student centered, self-directed, etc.) are well known, the components of a problem-based learning environment (PBLE) and the cognitive scaffolds necessary to support learning to solve different kinds of problems with different learners is less clear. This paper identifies the different…
Regression problems for magnitudes
NASA Astrophysics Data System (ADS)
Castellaro, S.; Mulargia, F.; Kagan, Y. Y.
2006-06-01
Least-squares linear regression is so popular that it is sometimes applied without checking whether its basic requirements are satisfied. In particular, in studying earthquake phenomena, the conditions (a) that the uncertainty on the independent variable is at least one order of magnitude smaller than the one on the dependent variable, (b) that both data and uncertainties are normally distributed and (c) that residuals are constant are at times disregarded. This may easily lead to wrong results. As an alternative to least squares, when the ratio between errors on the independent and the dependent variable can be estimated, orthogonal regression can be applied. We test the performance of orthogonal regression in its general form against Gaussian and non-Gaussian data and error distributions and compare it with standard least-square regression. General orthogonal regression is found to be superior or equal to the standard least squares in all the cases investigated and its use is recommended. We also compare the performance of orthogonal regression versus standard regression when, as often happens in the literature, the ratio between errors on the independent and the dependent variables cannot be estimated and is arbitrarily set to 1. We apply these results to magnitude scale conversion, which is a common problem in seismology, with important implications in seismic hazard evaluation, and analyse it through specific tests. Our analysis concludes that the commonly used standard regression may induce systematic errors in magnitude conversion as high as 0.3-0.4, and, even more importantly, this can introduce apparent catalogue incompleteness, as well as a heavy bias in estimates of the slope of the frequency-magnitude distributions. All this can be avoided by using the general orthogonal regression in magnitude conversions.
A taxonomy of inductive problems.
Kemp, Charles; Jern, Alan
2014-02-01
Inductive inferences about objects, features, categories, and relations have been studied for many years, but there are few attempts to chart the range of inductive problems that humans are able to solve. We present a taxonomy of inductive problems that helps to clarify the relationships between familiar inductive problems such as generalization, categorization, and identification, and that introduces new inductive problems for psychological investigation. Our taxonomy is founded on the idea that semantic knowledge is organized into systems of objects, features, categories, and relations, and we attempt to characterize all of the inductive problems that can arise when these systems are partially observed. Recent studies have begun to address some of the new problems in our taxonomy, and future work should aim to develop unified theories of inductive reasoning that explain how people solve all of the problems in the taxonomy.
NASA Technical Reports Server (NTRS)
Potter, Don; Serian, Charles; Sweet, Robert; Sapir, Babak; Gamez, Enrique; Mays, David
2008-01-01
The Problem Reporting System (PRS) is a Web application, running on two Web servers (load-balanced) and two database servers (RAID-5), which establishes a system for submission, editing, and sharing of reports to manage risk assessment of anomalies identified in NASA's flight projects. PRS consolidates diverse anomaly-reporting systems, maintains a rich database set, and incorporates a robust engine, which allows tracking of any hardware, software, or paper process by configuring an appropriate life cycle. Global and specific project administration and setup tools allow lifecycle tailoring, along with customizable controls for user, e-mail, notifications, and more. PRS is accessible via the World Wide Web for authorized user at most any location. Upon successful log-in, the user receives a customizable window, which displays time-critical 'To Do' items (anomalies requiring the user s input before the system moves the anomaly to the next phase of the lifecycle), anomalies originated by the user, anomalies the user has addressed, and custom queries that can be saved for future use. Access controls exist depending on a user's role as system administrator, project administrator, user, or developer, and then, further by association with user, project, subsystem, company, or item with provisions for business-to-business exclusions, limitations on access according to the covert or overt nature of a given project, all with multiple layers of filtration, as needed. Reporting of metrics is built in. There is a provision for proxy access (in which the user may choose to grant one or more other users to view screens and perform actions as though they were the user, during any part of a tracking life cycle - especially useful during tight build schedules and vacations to keep things moving). The system also provides users the ability to have an anomaly link to or notify other systems, including QA Inspection Reports, Safety, GIDEP (Government-Industry Data Exchange Program
ERIC Educational Resources Information Center
Yip, Vania T.; Ang, Rebecca P.; Ooi, Yoon Phaik; Fung, Daniel S. S.; Mehrotra, Kala; Sung, Min; Lim, Choon Guan
2013-01-01
Background: The high prevalence of attention problems in children warrants concern, as it is a risk factor for internalizing and externalizing problems. There lies a need to understand possible factors that may mediate this link so that interventions may be targeted to alleviate these mediators and interrupt the link between attention problems and…
What is a problem?: On problem-oriented interdisciplinarity.
Schmidt, Jan C
2011-06-01
Among others, the term "problem" plays a major role in the various attempts to characterize interdisciplinarity or transdisciplinarity, as used synonymously in this paper. Interdisciplinarity (ID) is regarded as "problem solving among science, technology and society" and as "problem orientation beyond disciplinary constraints" (cf. Frodeman et al.: The Oxford Handbook of Interdisciplinarity. Oxford University Press, Oxford, 2010). The point of departure of this paper is that the discourse and practice of ID have problems with the "problem". The objective here is to shed some light on the vague notion of "problem" in order to advocate a specific type of interdisciplinarity: problem-oriented interdisciplinarity. The outline is as follows: Taking an ex negativo approach, I will show what problem-oriented ID does not mean. Using references to well-established distinctions in philosophy of science, I will show three other types of ID that should not be placed under the umbrella term "problem-oriented ID": object-oriented ID ("ontology"), theory-oriented ID (epistemology), and method-oriented ID (methodology). Different philosophical thought traditions can be related to these distinguishable meanings. I will then clarify the notion of "problem" by looking at three systematic elements: an undesired (initial) state, a desired (goal) state, and the barriers in getting from the one to the other. These three elements include three related kinds of knowledge: systems, target, and transformation knowledge. This paper elaborates further methodological and epistemological elements of problem-oriented ID. It concludes by stressing that problem-oriented ID is the most needed as well as the most challenging type of ID.
Inverse problem in hydrogeology
NASA Astrophysics Data System (ADS)
Carrera, Jesús; Alcolea, Andrés; Medina, Agustín; Hidalgo, Juan; Slooten, Luit J.
2005-03-01
The state of the groundwater inverse problem is synthesized. Emphasis is placed on aquifer characterization, where modelers have to deal with conceptual model uncertainty (notably spatial and temporal variability), scale dependence, many types of unknown parameters (transmissivity, recharge, boundary conditions, etc.), nonlinearity, and often low sensitivity of state variables (typically heads and concentrations) to aquifer properties. Because of these difficulties, calibration cannot be separated from the modeling process, as it is sometimes done in other fields. Instead, it should be viewed as one step in the process of understanding aquifer behavior. In fact, it is shown that actual parameter estimation methods do not differ from each other in the essence, though they may differ in the computational details. It is argued that there is ample room for improvement in groundwater inversion: development of user-friendly codes, accommodation of variability through geostatistics, incorporation of geological information and different types of data (temperature, occurrence and concentration of isotopes, age, etc.), proper accounting of uncertainty, etc. Despite this, even with existing codes, automatic calibration facilitates enormously the task of modeling. Therefore, it is contended that its use should become standard practice. L'état du problème inverse des eaux souterraines est synthétisé. L'accent est placé sur la caractérisation de l'aquifère, où les modélisateurs doivent jouer avec l'incertitude des modèles conceptuels (notamment la variabilité spatiale et temporelle), les facteurs d'échelle, plusieurs inconnues sur différents paramètres (transmissivité, recharge, conditions aux limites, etc.), la non linéarité, et souvent la sensibilité de plusieurs variables d'état (charges hydrauliques, concentrations) des propriétés de l'aquifère. A cause de ces difficultés, le calibrage ne peut êtreséparé du processus de modélisation, comme c'est le
Emerging drug problems in Asia
Bart, Gavin
2014-01-01
This session, “Emerging Drug Problems in Asia,” focused on emerging drug problems in Asia. Dr. Juana Tomás-Rosselló discussed “East and Southeast Asia: Emerging Drug Problems and Response” and Dr. Wei J. Chen discussed “Ketamine Use among Regular Tobacco and Alcohol Users as Revealed by Respondent Driven Sampling in Taipei: Prevalence, Expectancy, and Users' Risky Decision Making.” PMID:25267884
Problem Solving Style, Creative Thinking, and Problem Solving Confidence
ERIC Educational Resources Information Center
Houtz, John C.; Selby, Edwin C.
2009-01-01
Forty-two undergraduate and graduate students completed VIEW: An Assessment of Problem Solving Style, the non-verbal Torrance Test Thinking Creatively with Pictures, and the Problem Solving Inventory (PSI). VIEW assesses individuals' orientation to change, manner of processing, and ways of deciding, while the Torrance test measures several…
Problem Structure and Performance on Two-Step Word Problems.
ERIC Educational Resources Information Center
Hocevar, Dennis; And Others
1987-01-01
The effects of problem structure on two-step word problems are analyzed in a sample of 91 fifth through eighth graders. Results showed that sequencing the first and second steps did not cause as much trouble as understanding the first step. (RB)
Pet Problems at Home: Pet Problems in the Community.
ERIC Educational Resources Information Center
Soltow, Willow
1984-01-01
Discusses problems of pets in the community, examining the community's role related to disruptive pets and pet overpopulation. Also discusses pet problems at home, offering advice on selecting a pet, meeting a pet's needs, and disciplining pets. Includes a list of books, films/filmstrips, teaching materials, and various instructional strategies.…
The generalized pole assignment problem. [dynamic output feedback problems
NASA Technical Reports Server (NTRS)
Djaferis, T. E.; Mitter, S. K.
1979-01-01
Two dynamic output feedback problems for a linear, strictly proper system are considered, along with their interrelationships. The problems are formulated in the frequency domain and investigated in terms of linear equations over rings of polynomials. Necessary and sufficient conditions are expressed using genericity.
Problem Effectiveness in a Course Using Problem-Based Learning.
ERIC Educational Resources Information Center
Dolmans, Diana H. J. M.
1993-01-01
A University of Limburg (Netherlands) medical school study investigated the relationship between student-generated learning issues and faculty instructional objectives (i.e., the effectiveness of the problems posed) in a problem-centered obstetrics and child development curriculum. Subjects were 120 students and 12 faculty. Results indicated…
Parent Problem Solving: Analysis of Problem Solving in Parenthood Transition.
ERIC Educational Resources Information Center
Alpert, Judith L.; And Others
The general purpose of this study was to explore the possibility of adapting the Means-Ends Problem-Solving procedure (MEPS) to the investigation of the individual's transition to parenthood. Specific purposes were to determine (1) the internal consistency of the Parent Problem-Solving Scale (PPSS), of its subclasses, and of a combined subscale;…
Students' Images of Problem Contexts when Solving Applied Problems
ERIC Educational Resources Information Center
Moore, Kevin C.; Carlson, Marilyn P.
2012-01-01
This article reports findings from an investigation of precalculus students' approaches to solving novel problems. We characterize the images that students constructed during their solution attempts and describe the degree to which they were successful in imagining how the quantities in a problem's context change together. Our analyses revealed…
Student Constructs of Mathematical Problems: Problem Types, Achievement and Gender
ERIC Educational Resources Information Center
Chiu, Mei-Shiu; Yeh, Huei-Ming; Whitebread, David
2014-01-01
This study aims to understand students' constructs regarding mathematical problems. Fifty-one Taiwanese primary students' constructs are elicited using interviews with the repertory grid technique based on their responses to creative and non-creative problems. The results of qualitative data analysis show that students' initial constructs can be…
Contextual Problem Solving Model Origination
ERIC Educational Resources Information Center
Ernst, Jeremy V.
2009-01-01
Problem solving has become a central focus of instructional activity in technology education classrooms at all levels (Boser, 1993). Impact assessment considerations incorporating society, culture, and economics are factors that require high-level deliberation involving critical thinking and the implementation of problem solving strategy. The…
ERIC Educational Resources Information Center
Glazer, Nathan
1994-01-01
Examines how social conditions can become social problems and argues that there are objective ways of determining the scale of a particular problem. The paper supports its argument through examinations of prohibition, the decline in tobacco consumption, and the war on drugs. (GLR)
Problem Solving, Scaffolding and Learning
ERIC Educational Resources Information Center
Lin, Shih-Yin
2012-01-01
Helping students to construct robust understanding of physics concepts and develop good solving skills is a central goal in many physics classrooms. This thesis examine students' problem solving abilities from different perspectives and explores strategies to scaffold students' learning. In studies involving analogical problem solving…
School Discipline: Problems Effecting Solutions.
ERIC Educational Resources Information Center
Heitzman, Andrew J.; Wiley, David B.
1987-01-01
Failure to solve school discipline problems is attributed to four factors: school district priorities, unclear problem dimensions, inadequate teacher training, and flaws in teacher/ administrator applied psychology. Psychological approaches that provide systems to control student behavior are described, including biophysical, interactionist, and…
Learning Impasses in Problem Solving
NASA Technical Reports Server (NTRS)
Hodgson, J. P. E.
1992-01-01
Problem Solving systems customarily use backtracking to deal with obstacles that they encounter in the course of trying to solve a problem. This paper outlines an approach in which the possible obstacles are investigated prior to the search for a solution. This provides a solution strategy that avoids backtracking.
ERIC Educational Resources Information Center
Jonas, Steven
1989-01-01
Concludes that the principle drug problems in the United States arise from the use of cigarette tobacco and alcoholic beverages. Identifies a drug culture as the persistent force in society that promotes drug use. Points out that the influence of the primary drug industries inhibit attempts to deal effectively with drug problems. (KO)
Students' Problem Solving and Justification
ERIC Educational Resources Information Center
Glass, Barbara; Maher, Carolyn A.
2004-01-01
This paper reports on methods of students' justifications of their solution to a problem in the area of combinatorics. From the analysis of the problem solving of 150 students in a variety of settings from high-school to graduate study, four major forms of reasoning evolved: (1) Justification by Cases, (2) Inductive Argument, (3) Elimination…
Difficulties in Genetics Problem Solving.
ERIC Educational Resources Information Center
Tolman, Richard R.
1982-01-01
Examined problem-solving strategies of 30 high school students as they solved genetics problems. Proposes a new sequence of teaching genetics based on results: meiosis, sex chromosomes, sex determination, sex-linked traits, monohybrid and dihybrid crosses (humans), codominance (humans), and Mendel's pea experiments. (JN)
The Cereal Box Problem Revisited.
ERIC Educational Resources Information Center
Wilkins, Jesse L. M.
1999-01-01
Investigates the cereal box problem using both an experimental and theoretical framework, and Monte Carlo methods. Using empirical data, students can discover patterns and relationships that help them understand the origin of the theoretical solution to the problem. Contains 17 references. (Author/ASK)
COPD and other health problems
... factors play a role in why people with COPD often have other health problems. Smoking is one of the biggest culprits. Smoking is a risk factor for most of the problems above. COPD usually develops in middle age. And people tend ...
Adolescent Problem-Solving Thinking
ERIC Educational Resources Information Center
Platt, Jerome J.; And Others
1974-01-01
The hypothesis that adolescent psychiatric patients would be deficient with respect to normal controls in their interpersonal problem-solving skills was tested by comparing the patient and control groups on seven tasks ref lecting different aspects of problem solving. (Author)
Creative Thinking and Problem Solving.
ERIC Educational Resources Information Center
Lacy, Grace
The booklet considers the nature of creativity in children and examines classroom implications. Among the topics addressed are the following: theories about creativity; research; developments in brain research; the creative process; creative problem solving; the Structure of Intellect Problem Solving (SIPS) model; a rationale for creativity in the…
Historical problem areas lessons learned
NASA Technical Reports Server (NTRS)
Sackheim, Bob; Fester, Dale A.
1991-01-01
Historical problem areas in space transportation propulsion technology are identified in viewgraph form. Problem areas discussed include materials compatibility, contamination, pneumatic/feed system flow instabilities, instabilities in rocket engine combustion and fuel sloshing, exhaust plume interference, composite rocket nozzle failure, and freeze/thaw damage.
Problem Based Learning in Science
ERIC Educational Resources Information Center
Pepper, Coral
2009-01-01
Problem based learning (PBL) is a recognised teaching and learning strategy used to engage students in deep rather than surface learning. It is also viewed as a successful strategy to align university courses with the real life professional work students are expected to undertake on graduation (Biggs, 2003). Problem based learning is practised…
Representations of an Osmosis Problem.
ERIC Educational Resources Information Center
Zuckerman, June Trop
1998-01-01
Explores whether students with several years of high school science are able to represent an osmosis problem correctly. The study problem features a typical osmotic system with students expected to make a graph to show how the solution level in the stem of the funnel changes over time. (DDR)
The Future Problem Solving Program.
ERIC Educational Resources Information Center
Crabbe, Anne B.
1989-01-01
Describes the Future Problem Solving Program, in which students from the U.S. and around the world are tackling some complex challenges facing society, ranging from acid rain to terrorism. The program uses a creative problem solving process developed for business and industry. A sixth-grade toxic waste cleanup project illustrates the process.…
ERIC Educational Resources Information Center
Callison, Daniel
1998-01-01
Presents a revised working definition of schema, lists four types of knowledge that individuals have (i.e., identification, elaboration, planning, and execution), and outlines issues in schema theory. The usefulness of schema in problem solving and information problem solving is discussed, and implications for teachers of information literacy are…
Problem Behaviors & Tourette Syndrome. Revised.
ERIC Educational Resources Information Center
Bruun, Ruth Dowling; And Others
This pamphlet discusses behavioral problems which are sometimes associated with Tourette Syndrome (TS), along with suggestions for parents to help manage these behaviors. Consideration is given to the following problems: obsessive-compulsive symptoms; attention deficit hyperactivity disorder; aggressive and explosive behaviors; self-injurious…
Sex Differences in Problem Solving.
ERIC Educational Resources Information Center
Johnson, Edward S.
1984-01-01
Nine experiments were performed to verify and extend studies on sex differences in problem solving conducted in the 1950s by Sweeney, Carey, Milton, Nakamura, and Berry. A 20-item problem set was administered to over 1,000 college students. Results indicated a male advantage, averaging 35 percent, virtually identical with 1950s results. (Author/BS)
Geothermal Energy: Prospects and Problems
ERIC Educational Resources Information Center
Ritter, William W.
1973-01-01
An examination of geothermal energy as a means of increasing the United States power resources with minimal pollution problems. Developed and planned geothermal-electric power installations around the world, capacities, installation dates, etc., are reviewed. Environmental impact, problems, etc. are discussed. (LK)
The Problems of Human Environment.
ERIC Educational Resources Information Center
United Nations, New York, NY.
Presented is a summary of considerations Specialized Agencies within the United Nations have given to the problems of the human environment. Uppermost are the problems of pollution--air, water, noise, marine, radiation, food, pesticide--as well as those of economic and social concern, environmental health, and misuse of the environment. Agencies…
Health Problems of Migrant Children.
ERIC Educational Resources Information Center
Michael, Robert J.; Salend, Spencer J.
1985-01-01
This investigation examined the incidence and types of health-related problems of migrant children as identified by school health medical personnel. Results indicated 615 of the 1,000 children in the sample had physical, visual, dental, auditory, immunization, or nutritional problems. Implications are discussed. (Author/MT)
Rethinking the American Race Problem.
ERIC Educational Resources Information Center
Brooks, Roy L.
Whereas political inequality was once seen as the key element of the American race problem, today the problem can be seen in terms of social and economic disparities. Three general socioeconomic classes have emerged in the United States, a middle class, a working class, and a poverty-stricken class. The status of African Americans can no longer be…
Problem Solving through Paper Folding
ERIC Educational Resources Information Center
Wares, Arsalan
2014-01-01
The purpose of this article is to describe a couple of challenging mathematical problems that involve paper folding. These problem-solving tasks can be used to foster geometric and algebraic thinking among students. The context of paper folding makes some of the abstract mathematical ideas involved relatively concrete. When implemented…
Promote Problem-Solving Discourse
ERIC Educational Resources Information Center
Bostic, Jonathan; Jacobbe, Tim
2010-01-01
Fourteen fifth-grade students gather at the front of the classroom as their summer school instructor introduces Jonathan Bostic as the mathematics teacher for the week. Before examining any math problems, Bostic sits at eye level with the students and informs them that they will solve problems over the next four days by working individually as…
"What Works" with Problem Learners.
ERIC Educational Resources Information Center
Swanson, Elizabeth F.; Halley, Mari Kirsch
1986-01-01
Describes the use of a structured, problem-solving dialog among teachers and between teacher and student to review successes in solving the instructional problems of a particular child and to develop an effective education plan which fosters student responsibility for learning and behavior. Uses a case study to illustrate the "What Works" process.…
ERIC Educational Resources Information Center
Greenwood, Jay, Ed.
1997-01-01
Presents the reflections of students on a problem given in May, 1996 issue of this journal in order to share the thinking of middle school students. The problem concerned weighing on a double per balance if given a clump of clay, and a 20-gram and 50-gram balance. (ASK)
Vaccination and the prevention problem.
Dawson, Angus
2004-11-01
This paper seeks to critically review a traditional objection to preventive medicine (which I call here the 'prevention problem'). The prevention problem is a concern about the supposedly inequitable distribution of benefits and risks of harm resulting from preventive medicine's focus on population-based interventions. This objection is potentially applicable to preventive vaccination programmes and could be used to argue that such programmes are unethical. I explore the structure of the prevention problem by focusing upon two different types of vaccination (therapeutic vaccination and preventive vaccination). I argue that the 'prevention problem' cannot be fairly applied to the case of preventive vaccination because such programmes do not just focus upon benefits at the level of populations (as is claimed by the prevention problem). Most such preventive vaccination programmes explicitly seek to create and maintain herd protection. I argue that herd protection is an important public good which is a benefit shared by all individuals in the relevant population. This fact can then be used to block the 'prevention problem' argument in relation to preventive vaccination programmes. I conclude by suggesting that whilst the future development and use of therapeutic vaccines does raise some interesting ethical issues, any ethical objections to prophylactic vaccination on the basis of the 'prevention problem' will not be overcome through the substitution of therapeutic vaccines for preventive vaccines; indeed, the 'prevention problem' fails on its own terms in relation to preventive vaccination programmes.
Problem Based Learning: Mystery Disease.
ERIC Educational Resources Information Center
Bohland, Mark A.
This guide features a problem-based learning (PBL) unit specifically designed for student-centered learning of new and meaningful content on diseases. Students grapple with a complex and changing problem that requires higher level thinking skills in an environment in which students work both individually and in collaboration with others. Includes…
Identifying problem and compulsive gamblers.
van Es, R.
2000-01-01
OBJECTIVE: To present a meta-analysis of current research on the prevalence, identification, and treatment of problem and compulsive gamblers. QUALITY OF EVIDENCE: Problem and compulsive gambling was not a socio-scientific concern until the last two decades. Hence research on this topic is limited. The summary and analysis for this paper relied on computer searches of journal and news abstracts in addition to direct contact with organizations addressing the identification and treatment of compulsive gamblers. MAIN MESSAGE: An estimated 5% of those who gamble run into problems. About 1% of those who gamble are predicted to experience serious problems. Successful treatment of problem and compulsive gambling continues to be a challenge. Although cognitive therapy has been the favoured approach, a combination of several therapeutic approaches is advocated. CONCLUSIONS: Problem and compulsive gambling can present a real health threat. As with other addictions, treatment strategies continue to be a baffling social problem. Aware and informed physicians can have a pivotal role in the difficult process of identifying, acknowledging, and remediating problem and compulsive gambling. PMID:10907572
Problem Solving vis Soap Bubbles
ERIC Educational Resources Information Center
Bader, William A.
1975-01-01
Describes the use of a scientific phenomenon related to the concept of surface tension as an intriguing vehicle to direct attention to useful problem solving techniques. The need for a definite building process in attempts to solve mathematical problems is stressed. (EB)
Pen Pals: Practicing Problem Solving
ERIC Educational Resources Information Center
Lampe, Kristen A.; Uselmann, Linda
2008-01-01
This article describes a semester-long pen-pal project in which preservice teachers composed mathematical problems and the middle school students worked for solutions. The college students assessed the solution and the middle school students provided feedback regarding the problem itself. (Contains 6 figures.)
A Typology of Planning Problems.
ERIC Educational Resources Information Center
Bean, John P.; Kuh, George D.
1984-01-01
A matrix of planning problems is developed to illustrate pitfalls typically encountered in formal planning. Problems with goals, participation, information and communication, interdependencies, and resources may occur at each of four planning stages: capacity to plan, and initiation, development, and implementation of plans. (Author/MLW)
Musielak, Z E; Quarles, B
2014-06-01
The three-body problem, which describes three masses interacting through Newtonian gravity without any restrictions imposed on the initial positions and velocities of these masses, has attracted the attention of many scientists for more than 300 years. In this paper, we present a review of the three-body problem in the context of both historical and modern developments. We describe the general and restricted (circular and elliptic) three-body problems, different analytical and numerical methods of finding solutions, methods for performing stability analysis and searching for periodic orbits and resonances. We apply the results to some interesting problems of celestial mechanics. We also provide a brief presentation of the general and restricted relativistic three-body problems, and discuss their astronomical applications. PMID:24913140
Musielak, Z E; Quarles, B
2014-06-01
The three-body problem, which describes three masses interacting through Newtonian gravity without any restrictions imposed on the initial positions and velocities of these masses, has attracted the attention of many scientists for more than 300 years. In this paper, we present a review of the three-body problem in the context of both historical and modern developments. We describe the general and restricted (circular and elliptic) three-body problems, different analytical and numerical methods of finding solutions, methods for performing stability analysis and searching for periodic orbits and resonances. We apply the results to some interesting problems of celestial mechanics. We also provide a brief presentation of the general and restricted relativistic three-body problems, and discuss their astronomical applications.
Sediment problems in urban areas
Guy, Harold P.
1970-01-01
One obstacle to a scientific recognition and an engineering solution to sediment-related environmental problems is that such problems are bound in conflicting and generally undefinable political and institutional restraints. Also, some of the difficulty may involve the fact that the scientist or engineer, because of his relatively narrow field of investigation, cannot always completely envision the less desirable effects of his work and communicate alternative solutions to the public. For example, the highway and motor-vehicle engineers have learned how to provide the means by which one can transport himself from one point to another with such great efficiency that a person's employment in this country is now commonly more than 5 miles from his residence. However, providing such efficient personal transport has created numerous serious environmental problems. Obstacles to recognition of and action to control sediment problems in and around urban areas are akin to other environmental problems with respect to the many scientific, engineering, economic, and social aspects.
Ten Problems in Experimental Mathematics
Bailey, David H.; Borwein, Jonathan M.; Kapoor, Vishaal; Weisstein, Eric
2004-09-30
This article was stimulated by the recent SIAM ''100 DigitChallenge'' of Nick Trefethen, beautifully described in a recent book. Indeed, these ten numeric challenge problems are also listed in a recent book by two of present authors, where they are followed by the ten symbolic/numeric challenge problems that are discussed in this article. Our intent was to present ten problems that are characteristic of the sorts of problems that commonly arise in ''experimental mathematics''. The challenge in each case is to obtain a high precision numeric evaluation of the quantity, and then, if possible, to obtain a symbolic answer, ideally one with proof. Our goal in this article is to provide solutions to these ten problems, and in the process present a concise account of how one combines symbolic and numeric computation, which may be termed ''hybrid computation'', in the process of mathematical discovery.
Application of Performance Problem-Solving to Educational Problems
ERIC Educational Resources Information Center
Bullock, Donald H.
1973-01-01
The relevance of performance problem-solving for education is discussed in terms of its effect on the marketability of graduates, the cost-effectiveness of educational programs, and the drop/push/failout rate. (Author)
Generating Problems from Problems and Solutions from Solutions
ERIC Educational Resources Information Center
Arcavi, Abraham; Resnick, Zippora
2008-01-01
This article describes a geometrical solution to a problem that is usually solved geometrically as an example of how alternative solutions may enrich the teaching and learning of mathematics. (Contains 11 figures.)
Problem solving stages in the five square problem
Fedor, Anna; Szathmáry, Eörs; Öllinger, Michael
2015-01-01
According to the restructuring hypothesis, insight problem solving typically progresses through consecutive stages of search, impasse, insight, and search again for someone, who solves the task. The order of these stages was determined through self-reports of problem solvers and has never been verified behaviorally. We asked whether individual analysis of problem solving attempts of participants revealed the same order of problem solving stages as defined by the theory and whether their subjective feelings corresponded to the problem solving stages they were in. Our participants tried to solve the Five-Square problem in an online task, while we recorded the time and trajectory of their stick movements. After the task they were asked about their feelings related to insight and some of them also had the possibility of reporting impasse while working on the task. We found that the majority of participants did not follow the classic four-stage model of insight, but had more complex sequences of problem solving stages, with search and impasse recurring several times. This means that the classic four-stage model is not sufficient to describe variability on the individual level. We revised the classic model and we provide a new model that can generate all sequences found. Solvers reported insight more often than non-solvers and non-solvers reported impasse more often than solvers, as expected; but participants did not report impasse more often during behaviorally defined impasse stages than during other stages. This shows that impasse reports might be unreliable indicators of impasse. Our study highlights the importance of individual analysis of problem solving behavior to verify insight theory. PMID:26300794
Problem solving stages in the five square problem.
Fedor, Anna; Szathmáry, Eörs; Öllinger, Michael
2015-01-01
According to the restructuring hypothesis, insight problem solving typically progresses through consecutive stages of search, impasse, insight, and search again for someone, who solves the task. The order of these stages was determined through self-reports of problem solvers and has never been verified behaviorally. We asked whether individual analysis of problem solving attempts of participants revealed the same order of problem solving stages as defined by the theory and whether their subjective feelings corresponded to the problem solving stages they were in. Our participants tried to solve the Five-Square problem in an online task, while we recorded the time and trajectory of their stick movements. After the task they were asked about their feelings related to insight and some of them also had the possibility of reporting impasse while working on the task. We found that the majority of participants did not follow the classic four-stage model of insight, but had more complex sequences of problem solving stages, with search and impasse recurring several times. This means that the classic four-stage model is not sufficient to describe variability on the individual level. We revised the classic model and we provide a new model that can generate all sequences found. Solvers reported insight more often than non-solvers and non-solvers reported impasse more often than solvers, as expected; but participants did not report impasse more often during behaviorally defined impasse stages than during other stages. This shows that impasse reports might be unreliable indicators of impasse. Our study highlights the importance of individual analysis of problem solving behavior to verify insight theory.
Civil law problems and morbidity
Pleasence, P; Balmer, N; Buck, A; O'Grady, A; Genn, H
2004-01-01
Study objective: In the United Kingdom, recognition of the links between social and health problems has led to government initiatives such as health action zones. The principles of civil law apply to many types of social problem, and the civil justice system provides one means through which they can be tackled. However, little research has been undertaken into the particular links between problems to which civil legal principles and processes can be applied and morbidity. This study examines these links, and the role of legal advice and services in preventing ill health. Design: This study examined survey respondents' self reports of longstanding illness/disability and experience of 18 problems to which legal principles can be applied. Setting: A random national survey conducted across England and Wales. Participants: 5611 adults drawn from 3348 residential households. Main results: Significant associations were found between illness/disability and 13 of the problem types. Moreover, experience of greater numbers of problems increased the likelihood of reported illness/disability. In attempting to resolve problems respondents' health also frequently suffered. Conclusions: This study highlights the contribution that public legal education and legal advice can make to the promotion of public health, and the importance of further integration of health and civil justice initiatives through health action zones, community legal service partnerships, etc, to further this end. PMID:15194714
NASA Astrophysics Data System (ADS)
Hossenfelder, Sabine
2014-07-01
The idea that Lorentz-symmetry in momentum space could be modified but still remain observer-independent has received quite some attention in the recent years. This modified Lorentz-symmetry, which has been argued to arise in Loop Quantum Gravity, is being used as a phenomenological model to test possibly observable effects of quantum gravity. The most pressing problem in these models is the treatment of multi-particle states, known as the 'soccer-ball problem'. This article briefly reviews the problem and the status of existing solution attempts.
General aviation IFR operational problems
NASA Technical Reports Server (NTRS)
Bolz, E. H.; Eisele, J. E.
1979-01-01
Operational problems of general aviation IFR operators (particularly single pilot operators) were studied. Several statistical bases were assembled and utilized to identify the more serious problems and to demonstrate their magnitude. These bases include official activity projections, historical accident data and delay data, among others. The GA operating environment and cockpit environment were analyzed in detail. Solutions proposed for each of the problem areas identified are based on direct consideration of currently planned enhancements to the ATC system, and on a realistic assessment of the present and future limitations of general aviation avionics. A coordinated set of research program is suggested which would provide the developments necessary to implement the proposed solutions.
Problems in nonlinear resistive MHD
Turnbull, A.D.; Strait, E.J.; La Haye, R.J.; Chu, M.S.; Miller, R.L.
1998-12-31
Two experimentally relevant problems can relatively easily be tackled by nonlinear MHD codes. Both problems require plasma rotation in addition to the nonlinear mode coupling and full geometry already incorporated into the codes, but no additional physics seems to be crucial. These problems discussed here are: (1) nonlinear coupling and interaction of multiple MHD modes near the B limit and (2) nonlinear coupling of the m/n = 1/1 sawtooth mode with higher n gongs and development of seed islands outside q = 1.
Robot, computer problem solving system
NASA Technical Reports Server (NTRS)
Becker, J. D.
1972-01-01
The development of a computer problem solving system is reported that considers physical problems faced by an artificial robot moving around in a complex environment. Fundamental interaction constraints with a real environment are simulated for the robot by visual scan and creation of an internal environmental model. The programming system used in constructing the problem solving system for the simulated robot and its simulated world environment is outlined together with the task that the system is capable of performing. A very general framework for understanding the relationship between an observed behavior and an adequate description of that behavior is included.
Imbalance problem in community detection
NASA Astrophysics Data System (ADS)
Sun, Peng Gang
2016-09-01
Community detection gives us a simple way to understand complex networks' structures. However, there is an imbalance problem in community detection. This paper first introduces the imbalance problem and then proposes a new measure to alleviate the imbalance problem. In addition, we study two variants of the measure and further analyze the resolution scale of community detection. Finally, we compare our approach with some state of the art methods on random networks as well as real-world networks for community detection. Both the theoretical analysis and the experimental results show that our approach achieves better performance for community detection. We also find that our approach tends to separate densely connected subgroups preferentially.
Critical problems of computational aeroacoustics
NASA Technical Reports Server (NTRS)
Rogers, Joel C. W.
1991-01-01
The aeroacoustics of rigid boundaries is discussed. Lighthill gave a formulation of this problem in which he showed that the sources of the acoustic field were quadrupole in nature. We have preferred a different formulation of the problem, in which the quadrupoles are sources for a nonlinear wave equation, as opposed to the linear one used by Lighthill. This is given here in a figure which also gives further details of a solution procedure for the Euler equations appropriate for the aeroelastic problem and motivated by the analysis of Crow. In accordance with our formulation, we contend that an algorithm for accurate solutions of an inhomogeneous nonlinear wave equation is of prime importance.
Quantum Computing: Solving Complex Problems
DiVincenzo, David [IBM Watson Research Center
2016-07-12
One of the motivating ideas of quantum computation was that there could be a new kind of machine that would solve hard problems in quantum mechanics. There has been significant progress towards the experimental realization of these machines (which I will review), but there are still many questions about how such a machine could solve computational problems of interest in quantum physics. New categorizations of the complexity of computational problems have now been invented to describe quantum simulation. The bad news is that some of these problems are believed to be intractable even on a quantum computer, falling into a quantum analog of the NP class. The good news is that there are many other new classifications of tractability that may apply to several situations of physical interest.
Systems management techniques and problems
NASA Technical Reports Server (NTRS)
1971-01-01
Report is reviewed which discusses history and trends of systems management, its basic principles, and nature of problems that lend themselves to systems approach. Report discusses systems engineering as applied to weapons acquisition, ecology, patient monitoring, and retail merchandise operations.
Spectral methods for discontinuous problems
NASA Technical Reports Server (NTRS)
Abarbanel, S.; Gottlieb, D.; Tadmor, E.
1985-01-01
Spectral methods yield high-order accuracy even when applied to problems with discontinuities, though not in the sense of pointwise accuracy. Two different procedures are presented which recover pointwise accurate approximations from the spectral calculations.
Problems in Recording the Electrocardiogram.
ERIC Educational Resources Information Center
Webster, John G.
The unwanted signals that arise in electrocardiography are discussed. A technical background of electrocardiography is given, along with teaching techniques that educate students of medical instrumentation to solve the problems caused by these signals. (MJH)
ERIC Educational Resources Information Center
Fodor, Jerry A.
1981-01-01
Describes several different philosophies of mind with each philosophy's explanation of the mind-body problem. Philosophies discussed include dualism, materialism, functionalism, radical behaviorism, logical behaviorism and central-state identity. (DS)
Corrosion Problems in Absorption Chillers
ERIC Educational Resources Information Center
Stetson, Bruce
1978-01-01
Absorption chillers use a lithium bromide solution as the medium of absorption and water as the refrigerant. Discussed are corrosion and related problems, tests and remedies, and cleaning procedures. (Author/MLF)
Problem Solving with General Semantics.
ERIC Educational Resources Information Center
Hewson, David
1996-01-01
Discusses how to use general semantics formulations to improve problem solving at home or at work--methods come from the areas of artificial intelligence/computer science, engineering, operations research, and psychology. (PA)
The unsolved problems of neuroscience
Adolphs, Ralph
2015-01-01
Some problems in neuroscience are nearly solved. For others, solutions are decades away. The current pace of advances in methods forces us to take stock, to ask where we are going, and what we should research next. PMID:25703689
Animal navigation: the longitude problem.
Gould, James L
2008-03-11
Determining longitude is incredibly difficult--for humans. Are animals fooling us into thinking that they have bicoordinate maps? New experiments show that at least some creatures effortlessly solve the seemingly insoluble problem of longitude.
Surrogate Guderley Test Problem Definition
Ramsey, Scott D.; Shashkov, Mikhail J.
2012-07-06
The surrogate Guderley problem (SGP) is a 'spherical shock tube' (or 'spherical driven implosion') designed to ease the notoriously subtle initialization of the true Guderley problem, while still maintaining a high degree of fidelity. In this problem (similar to the Guderley problem), an infinitely strong shock wave forms and converges in one-dimensional (1D) cylindrical or spherical symmetry through a polytropic gas with arbitrary adiabatic index {gamma}, uniform density {rho}{sub 0}, zero velocity, and negligible pre-shock pressure and specific internal energy (SIE). This shock proceeds to focus on the point or axis of symmetry at r = 0 (resulting in ostensibly infinite pressure, velocity, etc.) and reflect back out into the incoming perturbed gas.
Special Medical Problems of Athletes.
ERIC Educational Resources Information Center
Couch, Joan M.
1987-01-01
This article addresses the situations in which athletes with special needs and considerations participate in sports. The health problems discussed are diabetes mellitus, exercise-induced asthma, exercise-induced anaphylaxis, and epilepsy. (MT)
Late Blooming or Language Problem?
... and Swallowing / Disorders and Diseases Late Blooming or Language Problem? Parents are smart. They listen to their ... or not their child is developing speech and language at a normal rate. If parents think that ...
Sweating Over a Perspiration Problem?
... Problem? You might have a treatable condition called hyperhidrosis To use the sharing features on this page, ... Medical Center. People who sweat profusely might have hyperhidrosis, she explained. "If you think you might be ...
Nervous System Problems and Dementia
... especially when compared to reflexes in the knees. Magnetic Resonance Imaging (MRI,) a radiologic procedure, may show abnormalities in ... later stages of HIV disease. However, problems with memory can show up even in people with no ...
Families and Pediatric Feeding Problems
ERIC Educational Resources Information Center
Martorana, Pamela; Bove, Kelly; Scarcelli, Melissa
2008-01-01
When a child is born with a feeding and/or swallowing problem, it affects the entire family. Parents, mothers specifically, internalize the problem and come to believe it is due to something they've done. Families are put on an emotional rollercoaster with the ups and downs being dependant on how much the child has eaten that day. In this article,…
Multilevel techniques for nonelliptic problems
NASA Technical Reports Server (NTRS)
Jespersen, D. C.
1981-01-01
Multigrid and multilevel methods are extended to the solution of nonelliptic problems. A framework for analyzing these methods is established. A simple nonelliptic problem is given, and it is shown how a multilevel technique can be used for its solution. Emphasis is on smoothness properties of eigenvectors and attention is drawn to the possibility of conditioning the eigensystem so that eigenvectors have the desired smoothness properties.
Free boundary problems in biology.
Friedman, Avner
2015-09-13
In this paper, I review several free boundary problems that arise in the mathematical modelling of biological processes. The biological topics are quite diverse: cancer, wound healing, biofilms, granulomas and atherosclerosis. For each of these topics, I describe the biological background and the mathematical model, and then proceed to state mathematical results, including existence and uniqueness theorems, stability and asymptotic limits, and the behaviour of the free boundary. I also suggest, for each of the topics, open mathematical problems.
Distributed Weighted Stable Marriage Problem
NASA Astrophysics Data System (ADS)
Amira, Nir; Giladi, Ran; Lotker, Zvi
The Stable Matching problem was introduced by Gale and Shapley in 1962. The input for the stable matching problem is a complete bipartite K n,n graph together with a ranking for each node. Its output is a matching that does not contain a blocking pair, where a blocking pair is a pair of elements that are not matched together but rank each other higher than they rank their current mates. In this work we study the Distributed Weighted Stable Matching problem. The input to the Weighted Stable Matching problem is a complete bipartite K n,n graph and a weight function W. The ranking of each node is determined by W, i.e. node v prefers node u 1 over node u 2 if W((v,u 1)) > W((v, u 2)). Using this ranking we can solve the original Stable Matching problem. We consider two different communication models: the billboard model and the full distributed model. In the billboard model, we assume that there is a public billboard and each participant can write one message on it in each time step. In the distributed model, we assume that each node can send O(logn) bits on each edge of the K n,n . In the billboard model we prove a somewhat surprising tight bound: any algorithm that solves the Stable Matching problem requires at least n - 1 rounds. We provide an algorithm that meets this bound. In the distributed communication model we provide an algorithm named intermediation agencies algorithm, in short (IAA), that solves the Distributed Weighted Stable Marriage problem in O(sqrt{n}) rounds. This is the first sub-linear distributed algorithm that solves some subcase of the general Stable Marriage problem.
Diabetes and Sexual and Urologic Problems
... Disease, and Other Dental Problems Diabetic Eye Disease Diabetes and Sexual and Urologic Problems Troublesome bladder symptoms ... early onset of these sexual and urologic problems. Diabetes and Sexual Problems Both men and women with ...
Conceptual approach to astronomical problems
NASA Astrophysics Data System (ADS)
Skvortsov, N. A.; Avvakumova, E. A.; Bryukhov, D. O.; Vovchenko, A. E.; Vol'nova, A. A.; Dluzhnevskaya, O. B.; Kaigorodov, P. V.; Kalinichenko, L. A.; Kniazev, A. Yu.; Kovaleva, D. A.; Malkov, O. Yu.; Pozanenko, A. S.; Stupnikov, S. A.
2016-01-01
New technical capabilities have brought about the sweeping growth of the amount of data acquired by the astronomers from observations with different instruments in various parts of the electromagnetic spectrum. We consider conceptual approach to be a promising tool to efficiently deal with these data. It uses problem domain knowledge to formulate the tasks and develop problem-solving algorithms and data analysis methods in terms of domain concepts without reference to particular data sources, and thereby allows solving certain problems in general form. We demonstrate the benefits of conceptual approach by using it to solve problems related to search for secondary photometric standard candidates, determination of galaxy redshifts, creation of a binary and multiple star repository based on inhomogeneous databases, and classification of eclipsing binaries.We formulate and solve these problems over specifications of astronomical knowledge units such as photometric systems, astronomical objects, multiple stars, etc., and define them in terms of the corresponding problem domains independently of the existing data resources.
Stump problems in traumatic amputation.
Hirai, M; Tokuhiro, A; Takechi, H
1993-12-01
Stump problems in amputations resulting from employment related injuries were investigated in 397 cases in the Chugoku and Shikoku districts of Japan between 1987 and 1991. Ninety-seven patients (24%) had stump problems which interfered the prosthetic fitting. Stump problems of the upper extremity were seen in about 9% (17 amputees), two thirds of which were skin troubles. Stump problems of the lower extremity were seen in about 37% (80 amputees). Certain complaints were associated with specific methods of amputation; abnormal keratosis in Syme's amputation, equinus deformity in Chopart's amputation, reduced muscle power in above the knee (A/K) amputation and joint dysfunction in below the knee (B/K) amputation. Adequate prosthetic fitting was achieved by the modification of the socket and alignment in almost all amputees with stump problems. In only two cases, Chopart's amputation required subsequent Syme's amputation due to equinus deformity with abnormal keratosis. In almost every case, stump problems are avoidable by means of surgeons' deliberate evaluation of the affected limb and adequate choice of the amputation level.
Using Problem-Based Learning in Accounting
ERIC Educational Resources Information Center
Hansen, James D.
2006-01-01
In this article, the author describes the process of writing a problem-based learning (PBL) problem and shows how a typical end-of-chapter accounting problem can be converted to a PBL problem. PBL uses complex, real-world problems to motivate students to identify and research the concepts and principles they need to know to solve these problems.…
Aging and skilled problem solving.
Charness, N
1981-03-01
Information-processing models of problem solving too often are based on restrictive age ranges. On the other hand, gerontologists have investigated few problem-solving tasks and have rarely generated explicit models. As this article demonstrates, both fields can benefit by closer collaboration. One major issue in gerontology is whether aging is associated with irreversible decrement or developmental plasticity. If both processes occur, then an appropriate strategy for investigating aging is to equate age groups for molar problem-solving performance and search for differences in the underlying components. This strategy was adopted to examine the relation of age and skill to problem solving in chess. Chess players were selected to vary widely in age and skill such that these variables were uncorrelated. Problem-solving and memory tasks were administered. Skill level was the only significant predictor for accuracy in both a choose-a-move task and a speeded end-game evaluation task. Age (negatively) and skill (positively) jointly determined performance in an unexpected recall task. Efficient chunking in recall was positively related to skill, though negatively related to age. Recognition confidence, though not accuracy, was negatively related to age. Thus despite age-related declines in encoding and retrieval of information, older players match the problem-solving performance of equivalently skilled younger players. Apparently, they can search the problem space more efficiently, as evidenced by taking less time to select an equally good move. Models of chess skill that stress that role of encoding efficiency, as indexed by chunking in recall, need to be modified to account for performance over the life span.
National water resources and problems
Oltman, Roy E.; MacKichan, Kenneth A.; Mesnier, Glennon N.; Rainwater, Frank H.; Thomasson, Horace G.
1960-01-01
Water problems exist in all parts of the United States. Furthermore, the problems are becoming more acute and widespread as population and industry grow. The need is pressing for wider appreciation of the nature of water problems. This requires a background of basic facts about the occurrence of water, its quantity and quality, and the manner in which it is used. This report records some of these basic facts. The facts are that the United States as a whole is well endowed with water. Many water problems (which exist in our country) are caused, however,by poor distribution of water in time and place. Because the nationwide supply of water is large, any given locality could be supplied with water sufficient in quantity and suitable in quality, provided that those who need the water can pay the cost. For the most part, then, water problems are basically social and economic. While management is needed, both locally and regionally, with flexibility to respond to broad geographic patterns of economic and social development.
Approximating random quantum optimization problems
NASA Astrophysics Data System (ADS)
Hsu, B.; Laumann, C. R.; Läuchli, A. M.; Moessner, R.; Sondhi, S. L.
2013-06-01
We report a cluster of results regarding the difficulty of finding approximate ground states to typical instances of the quantum satisfiability problem k-body quantum satisfiability (k-QSAT) on large random graphs. As an approximation strategy, we optimize the solution space over “classical” product states, which in turn introduces a novel autonomous classical optimization problem, PSAT, over a space of continuous degrees of freedom rather than discrete bits. Our central results are (i) the derivation of a set of bounds and approximations in various limits of the problem, several of which we believe may be amenable to a rigorous treatment; (ii) a demonstration that an approximation based on a greedy algorithm borrowed from the study of frustrated magnetism performs well over a wide range in parameter space, and its performance reflects the structure of the solution space of random k-QSAT. Simulated annealing exhibits metastability in similar “hard” regions of parameter space; and (iii) a generalization of belief propagation algorithms introduced for classical problems to the case of continuous spins. This yields both approximate solutions, as well as insights into the free energy “landscape” of the approximation problem, including a so-called dynamical transition near the satisfiability threshold. Taken together, these results allow us to elucidate the phase diagram of random k-QSAT in a two-dimensional energy-density-clause-density space.
Computational problems in Arctic Research
NASA Astrophysics Data System (ADS)
Petrov, I.
2016-02-01
This article is to inform about main problems in the area of Arctic shelf seismic prospecting and exploitation of the Northern Sea Route: simulation of the interaction of different ice formations (icebergs, hummocks, and drifting ice floes) with fixed ice-resistant platforms; simulation of the interaction of icebreakers and ice- class vessels with ice formations; modeling of the impact of the ice formations on the underground pipelines; neutralization of damage for fixed and mobile offshore industrial structures from ice formations; calculation of the strength of the ground pipelines; transportation of hydrocarbons by pipeline; the problem of migration of large ice formations; modeling of the formation of ice hummocks on ice-resistant stationary platform; calculation the stability of fixed platforms; calculation dynamic processes in the water and air of the Arctic with the processing of data and its use to predict the dynamics of ice conditions; simulation of the formation of large icebergs, hummocks, large ice platforms; calculation of ridging in the dynamics of sea ice; direct and inverse problems of seismic prospecting in the Arctic; direct and inverse problems of electromagnetic prospecting of the Arctic. All these problems could be solved by up-to-date numerical methods, for example, using grid-characteristic method.
Problems of collisional stellar dynamics
NASA Astrophysics Data System (ADS)
Heggie, D. C.
2011-03-01
The discovery of dynamical friction was Chandrasekhar's best known contribution to the theory of stellar dynamics, but his work ranged from the few-body problem to the limit of large N (in effect, galaxies). Much of this work was summarised in the text "Principles of Stellar Dynamics" tep{C1942,C1960}, which ranges from a precise calculation of the time of relaxation, through a long analysis of galaxy models, to the behaviour of star clusters in tidal fields. The later edition also includes the work on dynamical friction and related issues. In this review we focus on progress in the collisional aspects of these problems, i.e. those where few-body interactions play a dominant role, and so we omit further discussion of galaxy dynamics. But we try to link Chandrasekhar's fundamental discoveries in collisional problems with the progress that has been made in the 50 years since the publication of the enlarged edition. There is one other such problem to which Chandrasekhar contributed, though the paper in question tep{C1944} was not reprinted in the book. See Section ref{sec:binaries}. For more on the collisionless problems studied by Chandrasekhar, see the paper by N. Wyn Evans (2011) in the present volume.
Three problems in potential flow
NASA Astrophysics Data System (ADS)
Whitley, N. L.
1982-05-01
There are three problems in plane potential flow, each treated separately. The collapse from rest of a mound of ideal fluid, under its own weight on an infinite horizontal plane, was approached in two different ways. An initial time problem for circular arc mounds was solved by conformal mapping and Green's functions. Initial displacements were computed. Secondly, the mound was assumed to be shallow and shallow water analysis was pursued. By appealing to the two approaches it was determined that the velocity potential is not analytic in time at the contact point and higher order shallow water solution will be lacking exponentially small terms. The classical problem of semi-infinite flow past a sinusoidal wall was attacked in two ways. One was to extend the small perturbation series in dimensionless wall height to fiftieth order by computer. The other approach was by direct variation using Kelvin's theorem of minimum kinetic energy. The method reduced the problem to solving a linear algebraic system. The problem of periodically forced (by free surface pressure or a base wall) free surface flow was attacked by the method of multiple scales. The two cases studied were that either, the forcing phenomena's temporal frequency wavelength combination lie on or near the dispersion curve for linear gravity waves, or that the double of it did.
Problem Solvers: Problem--Area beyond the Formula
ERIC Educational Resources Information Center
Dean, Chrystal
2014-01-01
In this article, associate professor Chrystal Dean describes how teachers can challenge their upper elementary students' understanding of area beyond a memorized formula. Herein she describes an activity that will show students the "why" behind using A = l × w to solve rectangular area problems. The activity will help deepen…
The Problem of Assessing Problem Solving: Can Comparative Judgement Help?
ERIC Educational Resources Information Center
Jones, Ian; Inglis, Matthew
2015-01-01
School mathematics examination papers are typically dominated by short, structured items that fail to assess sustained reasoning or problem solving. A contributory factor to this situation is the need for student work to be marked reliably by a large number of markers of varied experience and competence. We report a study that tested an…
Solving Optimization Problems with Dynamic Geometry Software: The Airport Problem
ERIC Educational Resources Information Center
Contreras, José
2014-01-01
This paper describes how the author's students (in-service and pre-service secondary mathematics teachers) enrolled in college geometry courses use the Geometers' Sketchpad (GSP) to gain insight to formulate, confirm, test, and refine conjectures to solve the classical airport problem for triangles. The students are then provided with strategic…
Theoretical Problems in Materials Science
NASA Technical Reports Server (NTRS)
Langer, J. S.; Glicksman, M. E.
1985-01-01
Interactions between theoretical physics and material sciences to identify problems of common interest in which some of the powerful theoretical approaches developed for other branches of physics may be applied to problems in materials science are presented. A unique structure was identified in rapidly quenched Al-14% Mn. The material has long-range directed bonds with icosahedral symmetry which does not form a regular structure but instead forms an amorphous-like quasiperiodic structure. Finite volume fractions of second phase material is advanced and is coupled with nucleation theory to describe the formation and structure of precipitating phases in alloys. Application of the theory of pattern formation to the problem of dendrite formation is studied.
Career problems of women doctors.
Henryk-Gutt, R; Silverstone, R
1976-09-01
Information was received from 61 women doctors who were having difficulty continuing with medical careers. Two main problems were disclosed. Firstly, despite the special arrangements made for women doctors, it is difficult to obtain postgraduate training. The provision of supernumerary posts does not seem to offer a satisfactory solution. Secondly, doctors who have completed postgraduate training but cannot yet return to full-time work are unable to obtain posts at an appropriate level. Both of these problems stem primarily from the need for part-time work by the mothers of young children. Most of the doctors wish to return to full-time or nearly full-time work when family responsibilities are fewer. In view of the increasing proportion of women doctors it seems important that large numbers are not unnecessarily lost from professional work. Some possible approaches to solving the problems are suggested.
Challenge problems for artificial intelligence
Selman, B.; Brooks, R.A.; Dean, T.
1996-12-31
AI textbooks and papers of ten discuss the big questions, such as {open_quotes}how to reason with uncertainty{close_quotes}, {open_quotes}how to reason efficiently{close_quotes}, or {open_quotes}how to improve performance through learning.{close_quotes} It is more difficult, however, to find descriptions of concrete problems or challenges that are still ambitious and interesting, yet not so open-ended. The goal of this panel is to formulate a set of such challenge problems for the field. Each panelist was asked to formulate one or more challenges. The emphasis is on problems for which there is a good chance that they will be resolved within the next five to ten years.
Interference problems for nongeostationary satellites
NASA Technical Reports Server (NTRS)
Sollfrey, W.
1984-01-01
The interference problems faced by nongeostationary satellites may be of major significance. A general discussion indicates the scope of the problems and describes several configurations of importance. Computer programs are described, which are employed by NASA/JPL and the U.S. Air Force Satellite Control Facility to provide interference-free scheduling of commands and data transmission. Satellite system mission planners are not concerned with the precise prediction of interference episodes, but rather with the expected total amount of interference, the mean and maximum duration of events, and the mean spacing between episodes. The procedures in the theory of probability developed by the author which permit calculation of such quantities are described and applied to several real cases. It may be anticipated that the problems will become steadily worse in the future as more and more data transmissions attempt to occupy the same frequency band.
Food production -- problems and prospects.
Anifowoshe, T O
1990-03-01
Improvements are needed in balancing the problems associated with population growth and food production. A review of the problems of rapid population growth and declining food production and suggestions for resolution are given. World population has increased over the past 10 years by 760 million, which is equal to adding the combined population of Africa and South America. Future increases are expected to bring total population to 6.1 billion by the year 2000 and 8.2 billion in 2025 (exponential increases). Food production/capita has declined since 1971 in the world and in Nigeria, particularly in the recent past. The food production problem is technical, environmental, social, political, and economic. Various scientific and technological methods for increasing food production are identified: mechanization, irrigation, use of fertilizers, control of weeds and insects, new varieties of farm animals or high-yielding strains of grain, land reclamation, soil conservation, river basin development, adequate storage facilities, infrastructure development, and birth control. Economic and social approaches involve short-term and long-term strategies in social readjustment and institutional change. For instance, large scale farmers should become contract growers for certain firms. Bureaucratic red tape should be eliminated in institutions which provide agricultural services. Environmental problems need urgent attention. Some of these problems are soil erosion from mechanization, water salinization from irrigation, accumulation of DDT in food and water and animal life from pesticide use, and water pollution from chemical fertilizers. Food production can be increased with more ecologically sound practices. Information about weather and weather forecasting allows for more suitable land management. The influence of rainfall (the amount and distribution) in Nigeria is greater than any other climatic factor. Solar radiation is a significant feature in production of dry matter and
[Psychological problems of thalassemic subjects].
Guasco, G; Gamalero, P C; Cuniolo, A
1985-01-01
Analysis of psychological problems of the thalassemic subject shown with these following tests: T.A.T., Rogers, Rosenzweig. Moreover, we made meetings with all boys and their parents during their stay in the day-hospital. These tests have shown subjective conflicts (fear and uncertainty of future due to the illness felt as aggression and fault, depressive moods and loneliness, problems of communication, hope in a magic recovery opposite to the constant discomfort of the therapeutic dependence) and relational conflicts (ambivalence towards parents, difficulties in becoming a part of the social and school environment).
[Psychological problems of thalassemic subjects].
Guasco, G; La Mantia, A; Cuniolo, A
1987-01-01
Analysis of psychological problems of the thalassemic subject shown with these following tests: Der Baumtest, drawing of the human figure. Moreover, we made meetings with all boys and their parents during their stay in the day-hospital. These tests have shown subjective conflicts (fear and uncertainty of future due to illness felt as aggression and fault, depressive moods and loneliness, problems of communication, hope in a magic recovery opposite to the constant discomfort of the therapeutic dependence) and relational conflicts (ambivalence towards parents, difficulties in becoming a part of the social and school environment).
Stable vices and trailer problems.
Houpt, K A
1986-12-01
Stable vices include oral vices such as cribbing, wood chewing, and coprophagia, as well as stall walking, weaving, pawing, and stall kicking. Some of these behaviors are escape behaviors; others are forms of self-stimulation. Most can be eliminated by pasturing rather than stall confinement. Trailering problems include failure to load, scrambling in the moving trailer, struggling in the stationary trailer, and refusal to unload. Gradual habituation to entering the trailer, the presence of another horse, or a change in trailer type can be used to treat these problems. PMID:3492249
Foliage problem in interferometric SAR
NASA Astrophysics Data System (ADS)
Rogers, George W.; Mansfield, Arthur W.; Roth, Duane; Poehler, Paul L.; Rais, Houra
1999-08-01
Interferometric SAR exploits the coherent nature of multiple synthetic aperture radar images to recover phase (range difference) information and thence terrain evaluation data as well as other phase derivative products such as Coherent Change Detection (CCD). Of the numerous factors that can degrade the coherency of multiple SAR collections, foliage constitutes one of the most challenging. The foliage problem in IFSAR is discussed and an airborne multiple pass collection is used to illustrate some facets of the problem. Resolution as a variable in the tradeoff between the bias and variance of the interferogram is discussed in the context of the example.
The dynamic sphere test problem
Chabaud, Brandon M.; Brock, Jerry S.; Smith, Brandon M.
2012-05-16
In this manuscript we define the dynamic sphere problem as a spherical shell composed of a homogeneous, linearly elastic material. The material exhibits either isotropic or transverse isotropic symmetry. When the problem is formulated in material coordinates, the balance of mass equation is satisfied automatically. Also, the material is assumed to be kept at constant temperature, so the only relevant equation is the equation of motion. The shell has inner radius r{sub i} and outer radius r{sub o}. Initially, the shell is at rest. We assume that the interior of the shell is a void and we apply a time-varying radial stress on the outer surface.
Symmetries in the Schwarzschild Problem
NASA Astrophysics Data System (ADS)
Mioc, V.
The two-body problem associated to a force field described by a potential of the form U = A/r + B/r3 (r is a distance between particles, A and B are real parameters) is resumed from the only standpoint of symmetries. Such symmetries, expressed in Hamiltonian coordinates, or in standard polar coordinates, are recovered for McGehee-type coordinates of both collision-blow-up and infinity-blow-up kind. They form isomorphic commutative groups endowed with an idempotent structure. Expressed in Levi-Civita's coordinates, the problem exhibits a larger group of symmetries, also commutative and presenting an idempotent structure.
Solving the wrong hierarchy problem
NASA Astrophysics Data System (ADS)
Blinov, Nikita; Hook, Anson
2016-06-01
Many theories require augmenting the Standard Model with additional scalar fields with large order one couplings. We present a new solution to the hierarchy problem for these scalar fields. We explore parity- and Z_2 -symmetric theories where the Standard Model Higgs potential has two vacua. The parity or Z_2 copy of the Higgs lives in the minimum far from the origin while our Higgs occupies the minimum near the origin of the potential. This approach results in a theory with multiple light scalar fields but with only a single hierarchy problem, since the bare mass is tied to the Higgs mass by a discrete symmetry. The new scalar does not have a new hierarchy problem associated with it because its expectation value and mass are generated by dimensional transmutation of the scalar quartic coupling. The location of the second Higgs minimum is not a free parameter, but is rather a function of the matter content of the theory. As a result, these theories are extremely predictive. We develop this idea in the context of a solution to the strong CP problem. We show this mechanism postdicts the top Yukawa to be within 1 σ of the currently measured value and predicts scalar color octets with masses in the range 9-200 TeV.
Problem Based Learning in Metaverse
ERIC Educational Resources Information Center
Barry, Dana M.; Kanematsu, Hideyuki; Fukumura, Yoshimi
2010-01-01
Problem Based Learning (PBL) is a powerful tool for both science and engineering education in the real world. Therefore, Japanese educators/researchers (with assistance from a US educator) carried out a pilot study to determine the effectiveness of using PBL activities in Metaverse. Their project was carried out by student teams from the US and…
Famous Problems and Their Mathematicians.
ERIC Educational Resources Information Center
Johnson, Art
Beginning with more than 60 mathematics problems commonly taught in middle and high school, this book shares the excitement and mystery of mathematics, shows students how 60 mathematicians discovered mathematical solutions, and demonstrates how these discoveries can be applied to everyday situations. Each chapter presents the historical background…
ERIC Educational Resources Information Center
Raymond, James C., Ed.
First presented as papers in a symposium on literacy conducted at the University of Alabama, essays in this volume explore three areas of human literacy--law, linguistics, and the English language; testing; and literacy's relation with culture and human consciousness. Following an introduction examining literacy as a human problem, the following…
ERIC Educational Resources Information Center
Moss, Peter
2010-01-01
At a time when English has emerged as the dominant language of academic communication, there is a disturbing silence about the risks and problems attendant on this development and a failure to ask critical questions about its consequences. Who gains and who loses? What is lost in translation? What are the consequences of one way linguistic…
Investigating the Antibiotic Resistance Problem.
ERIC Educational Resources Information Center
Lawson, Michael; Lawson, Amy L.
1998-01-01
Seeks to give teachers useful information on the extent of the problem of antibiotic-resistant bacteria, mechanisms bacteria use to resist antibiotics, the causes of the emergence of antibiotic-resistant organisms, and practices that can prevent or reverse this trend. Contains 19 references. (DDR)
University Presses: Problems and Prospects.
ERIC Educational Resources Information Center
Meeker, Robert B.
Historical information on university presses and their problems are considered. University presses in the United States have their roots in 15th century England when the Oxford University Press was established in 1478. The first U.S. press to use the term "university press" was Cornell University; the press operated from 1869 until it was closed…
Robot computer problem solving system
NASA Technical Reports Server (NTRS)
Becker, J. D.; Merriam, E. W.
1974-01-01
The conceptual, experimental, and practical aspects of the development of a robot computer problem solving system were investigated. The distinctive characteristics were formulated of the approach taken in relation to various studies of cognition and robotics. Vehicle and eye control systems were structured, and the information to be generated by the visual system is defined.
ERIC Educational Resources Information Center
Eberstadt, Mary
2003-01-01
Experts believe that child obesity is a serious medical problem that affects people in all socioeconomic groups. Suggests that there is a relationship between absentee parents, particularly mothers, and obese children, focusing on working/absentee mothers, television watching habits, the prophylactic effect of breastfeeding, and poor exercise…
Childhood Obesity: A Heavy Problem
ERIC Educational Resources Information Center
Costley, Kevin C.; Leggett, Timothy
2010-01-01
The youth of today are faced with a big problem; they are becoming more obese every day. The time of children playing outside all day and being extremely active has been overtaken by the television and video games. The days of sitting down as a family and eating a good healthy meal has been replaced by the rush to the nearest fast food…
Gender and Mathematical Problem Solving.
ERIC Educational Resources Information Center
Duffy, Jim; Gunther, Georg; Walters, Lloyd
1997-01-01
Studied the relationship between gender and mathematical problem solving in 83 male and 76 female high achieving Canadian 12-year-olds. Gender differences were found on the Canadian Test of Basic Skills but not on the GAUSS assessment. Implications for the discussion of the origin of gender differences in mathematics are discussed. (SLD)
Selected Problems in Sports Safety.
ERIC Educational Resources Information Center
American Alliance for Health, Physical Education, and Recreation, Washington, DC.
This publication, covering a broad spectrum of sports safety problems, is designed as a source of information for those who plan, organize, administer, or evaluate various physical education and recreational activities, athletics, or sports. In the first section, the prevention of sports injury is stressed with attention to different age groups…
Urban Problems and Community Development.
ERIC Educational Resources Information Center
Ferguson, Ronald F., Ed.; Dickens, William T., Ed.
The essays in this collection promote a conception of community development that entails building practical capacities to improve the quality of life among residents of targeted neighborhoods. The causes, consequences, and potential solutions of urban problems that lie both inside and outside neighborhood borders are emphasized. The chapters are:…
Environmental Problems and the Scientist
ERIC Educational Resources Information Center
Batisse, Michel
1973-01-01
Suggests that any environmental problem can be traced at biosphere, technosphere, sociosphere, and noosphere level. Scientists have generally ignored the latter two spheres in making scientific discoveries. New social ethics need to be recognized that are based on progress, and scientists must consider how these ethics are influenced by their…
Robot, computer problem solving system
NASA Technical Reports Server (NTRS)
Becker, J. D.; Merriam, E. W.
1973-01-01
The TENEX computer system, the ARPA network, and computer language design technology was applied to support the complex system programs. By combining the pragmatic and theoretical aspects of robot development, an approach is created which is grounded in realism, but which also has at its disposal the power that comes from looking at complex problems from an abstract analytical point of view.
The Problem with Toxic Wastes.
ERIC Educational Resources Information Center
Beecher, John L.; Fossa, Arthur J.
1980-01-01
Traced is the historical development of toxic waste problems in western New York State from 1825 to the present. Three major data sources are described: Industrial Chemical Survey, Inventory of Industrial Waste Generation Study, and the Interagency Task Force Study, developed by the Department of Environmental Conservation to prevent future…
Eldercare at Home: Communication Problems
... t remember the word, the name of the game." You might ask how to play the game, where it is played, or offer a few ... Plan Isn't Working If communication problems are serious and persist, review the section on "When to ...
Customer Service & Team Problem Solving.
ERIC Educational Resources Information Center
Martin, Sabrina Budasi
This curriculum guide provides materials for a six-session, site-specific training course in customer service and team problem solving for the Claretian Medical Center. The course outline is followed the six lesson plans. Components of each lesson plan include a list of objectives, an outline of activities and discussion topics for the lesson,…
Rosetta Stones for Energy Problems.
ERIC Educational Resources Information Center
Hayden, Howard C.
1981-01-01
Demonstrates, using specific problems, how various energy units can be converted to joules and power units to watts. Conversion tables are provided for power, energy, generation values, thermal insulation, consumption values, sunlight, with tables also on metric prefixes and time conversions. (SK)
Special Problems of Institutional Researchers.
ERIC Educational Resources Information Center
Center for Educational Management Studies, Honolulu, HI.
Papers from a forum sponsored by the Association for Institutional Research address the role problems of institutional researchers and the special position of institutional research in institutions of higher education and the issues that lead to conflict between institutional research, data gathering activities, and the faculty. In "Dilemmas in…
Uncommon Infant and Newborn Problems
It can be scary when your baby is sick, especially when it is not an everyday problem like a cold or a fever. You may not know whether the ... treat it. If you have concerns about your baby's health, call your health care provider right away. ...
Personal Law and Consumer Problems
ERIC Educational Resources Information Center
Graf, David
1972-01-01
There is little doubt at Minnetonka High School that the integrated personal law and consumer problems course is effective. The areas studied promote variety, concentration on vital matters, and student interest in the business department as a source of general education. (Author)
ERIC Educational Resources Information Center
Czarra, Fred R.; Long, Cathryn J., Eds.
1983-01-01
The major hunger problem today is chronic undernutrition, the primary cause of which is poverty. Hunger can be alleviated through food supplements, nutrition programs, and disaster relief. It can be eliminated by redistributing existing wealth and producing enough food and through equitable economic growth and a world food security system. (CS)
School Curricula and Social Problems.
ERIC Educational Resources Information Center
Gozzer, Giovanni
1990-01-01
Explores how curricular changes reflect modernization and its attendant social problems. Examines influences of decentralized and centralized systems, and degree of national identity, on curriculum development. Considers types of new subjects (e.g., anti-drug education) and the risks of overloading curricula with subjects of a relatively…
Eldercare at Home: Hearing Problems
... members and friends to comment on how much communication has improved when your mother is wearing the hearing aid. If your mother is concerned about the appearance of a hearing aid, tell her that most women can style their hair to cover the hearing aids. Problem " ...
Dyslexia: Problems of Reading Disabilities.
ERIC Educational Resources Information Center
Goldberg, Herman K.; Schiffman, Gilbert B.
The purpose of this book is to provide an understanding of both the educational and medical aspects of reading and to show how they are interrelated in reading disabilities. The various aspects of reading disabilities are presented in the following chapters: Introduction to the Reading Problem; Early Predictive Studies; Psychological Evaluation;…
Energy: A Growing National Problem?
ERIC Educational Resources Information Center
National Wildlife Federation, Washington, DC.
This publication highlights information about the energy problem and indicates some possible solutions. Americans must find new energy sources and more efficient ways to utilize existing energy supplies. The National Wildlife Federation urges conservation of existing fuel supplies, exploration of new potential energy sources, adaption of some…
Problem Solvers' Conceptions about Osmosis.
ERIC Educational Resources Information Center
Zuckerman, June T.
1994-01-01
Discusses the scheme and findings of a study designed to identify the conceptual knowledge used by high school students to solve a significant problem related to osmosis. Useful tips are provided to teachers to aid students in developing constructs that maximize understanding. (ZWH)
Adopting Children with Attachment Problems.
ERIC Educational Resources Information Center
Hughes, Daniel A.
1999-01-01
Notes that attachment behavior in infants is a facet of normal child development, and that children with attachment problems require special attention during and after the adoption process. Presents actions needed to increase the probability that such children can be successfully adopted, detailed attachment patterns, and parenting strategies and…
Problem Gambling on College Campuses
ERIC Educational Resources Information Center
McComb, Jennifer L.; Hanson, William E.
2009-01-01
The vast majority of college students gamble, with some doing so problematically. This article discusses gambling and problem gambling among college students, framing it as an emerging health issue on college campuses nationwide. Given that 4 out of 5 college students admit to gambling, and that approximately 8% gamble problematically, it is…
Problems with German Science Education.
ERIC Educational Resources Information Center
Riess, Falk
2000-01-01
The main problems of science teaching in Germany are students' lack of interest and motivation and their poor understanding of scientific concepts, ideas, methods, and results. Lists examples from science curricula and textbooks and describes some reform projects in Germany. Proposes a compensatory program in order to create prerequisites for…
ERIC Educational Resources Information Center
Pizlo, Zygmunt
2007-01-01
This paper presents a bibliography of a little more than 100 references related to human problem solving, arranged by subject matter. The references were taken from PsycInfo and Compendex databases. Only journal papers, books and dissertations are included. The topics include human development, education, neuroscience, research in applied…
Energy Problems Provide Job Opportunities.
ERIC Educational Resources Information Center
Moore, Allen B.
In response to the problems created by a diminishing energy supply but an increasing energy demand, this second in a series of national reports studies the linkage of vocational education and energy. Through an examination of selected literature with reference to types of energy resources, the author identifies the emerging occupations related to…
Robot computer problem solving system
NASA Technical Reports Server (NTRS)
Becker, J. D.; Merriam, E. W.
1974-01-01
The conceptual, experimental, and practical phases of developing a robot computer problem solving system are outlined. Robot intelligence, conversion of the programming language SAIL to run under the THNEX monitor, and the use of the network to run several cooperating jobs at different sites are discussed.
Theoretical problems of spiral galaxies
NASA Technical Reports Server (NTRS)
Yuan, C.
1982-01-01
Three theoretical problems concerning the large scale structure of disk galaxies in general, and the Milky Way System, in particular, were proposed to study. They are, namely, modes of spiral density waves, evolutionary change of the abundance distribution of the gas in the Milky Way System and the motions of the cloud medium behind the large scale galactic shock.
Polyomino Problems to Confuse Computers
ERIC Educational Resources Information Center
Coffin, Stewart
2009-01-01
Computers are very good at solving certain types combinatorial problems, such as fitting sets of polyomino pieces into square or rectangular trays of a given size. However, most puzzle-solving programs now in use assume orthogonal arrangements. When one departs from the usual square grid layout, complications arise. The author--using a computer,…
PROBLEMS IN MODERN GREEK LEXICOGRAPHY.
ERIC Educational Resources Information Center
KAHANE, HENRY; KAHANE, RENEE
PROBLEMS DEALING WITH LEVELS OF SPEECH AND LEVELS OF ANALYSIS IN CONNECTION WITH MODERN GREEK LEXICOGRAPHICAL STUDY WERE DISCUSSED. CONCERNING THE POSSIBLE CONSTRUCTION OF A COMPETENT BILINGUAL DICTIONARY, THE INVESTIGATORS SUGGESTED THAT THE VARIOUS STRUCTURES (NAMELY, PHONOLOGY, MORPHOLOGY, AND SYNTAX) BE TIED TOGETHER TO INVOLVE (1) LISTING IN…
Psychological Problems in Mental Deficiency.
ERIC Educational Resources Information Center
Sarason, Seymour B.; Doris, John
A statement of goals and the rationale for organization precede a historical discussion of mental deficiency and society. The problem of labels like IQ and brain injured and the consequences of the diagnostic process are illustrated by case histories; case studies are also used to examine the criteria used to decide who is retarded and to discuss…
Malaysian Serials: Issues and Problems.
ERIC Educational Resources Information Center
Bahri, Che Norma
This paper analyzes the issues and problems while looking at the trends and developments of serials publishing in Malaysia. The first section provides background; topics addressed include the country and people of Malaysia, the history of serials publishing in Malaysia, categories and formats of serials publishing, academic publications,…
Introduction: Unsolved Problems on Noise
NASA Astrophysics Data System (ADS)
Oriols, X.; Ciliberto, S.
2016-05-01
This paper is an introduction to the special issue of the 7th Int. Conf. on Unsolved Problems on Noise (UPoN) that took place at Casa Convalescència in Barcelona (Spain) in July 2015. The aim of the UPoN conferences is to provide a forum for researchers working on different fields of noise, fluctuations and variability, where they present their scientific problems which resist solutions. The papers of this Special Issue reflect the interdisciplinary topics (physics, biology, circuits, financial markets, psychology, technology, etc) presented at the UPoN conference. Noise is not only a hindrance to signal detection, but it is indeed a valuable source of information (not present in the signal) that help us to get a deeper understanding on how Nature works. This special issue of the 7th International Conference on Unsolved Problems on Noise (UPoN) is dedicated to Laszlo Kish in the occasion of his 60th birthday. He organized the first edition of these UPoN conferences in Szeged (Hungary) in 1996. Many of us have greatly benefited from his ‘volcanic imagination in tackling new problems from unconventional points of views’.
ERIC Educational Resources Information Center
Demana, Franklin; Waits, Bert K.
1993-01-01
Discusses solutions to real-world linear particle-motion problems using graphing calculators to simulate the motion and traditional analytic methods of calculus. Applications include (1) changing circular or curvilinear motion into linear motion and (2) linear particle accelerators in physics. (MDH)
Teaching through Collaborative Problem Solving.
ERIC Educational Resources Information Center
Blandford, A. E.
1994-01-01
Discussion of a prototype intelligent education system called WOMBAT (Weighted Objectives Method by Arguing with the Tutor) focuses on dialogue and negotiation in collaborative problem solving. The results of a formative evaluation, in which the system was used by 10 subjects who commented on various aspects of the design, are presented. (Contains…
Solving the wrong hierarchy problem
Blinov, Nikita; Hook, Anson
2016-06-29
Many theories require augmenting the Standard Model with additional scalar fields with large order one couplings. We present a new solution to the hierarchy problem for these scalar fields. We explore parity- and Z2-symmetric theories where the Standard Model Higgs potential has two vacua. The parity or Z2 copy of the Higgs lives in the minimum far from the origin while our Higgs occupies the minimum near the origin of the potential. This approach results in a theory with multiple light scalar fields but with only a single hierarchy problem, since the bare mass is tied to the Higgs massmore » by a discrete symmetry. The new scalar does not have a new hierarchy problem associated with it because its expectation value and mass are generated by dimensional transmutation of the scalar quartic coupling. The location of the second Higgs minimum is not a free parameter, but is rather a function of the matter content of the theory. As a result, these theories are extremely predictive. We develop this idea in the context of a solution to the strong CP problem. Lastly, we show this mechanism postdicts the top Yukawa to be within 1σ of the currently measured value and predicts scalar color octets with masses in the range 9-200 TeV.« less
[Microbial sensors: achievements, problems, prospects].
Korpan, Ia I; El'skaia, A V
1995-12-01
The review summarizes the literature data on the design of laboratory and commercial types of biosensors based on living cells of microorganisms. The following aspects are discussed: microbiological, biochemical and physical fundamentals of microbial sensors; operation modes and fields of application of cell-based biosensors; immobilization technique for biological recognition systems; benefits and problems in this field of biotechnology.
"Top School Problems" Are Myths.
ERIC Educational Resources Information Center
Males, Mike
1992-01-01
A well-known "study" comparing the top school problems of 1940 (talking and gum chewing) with those of 1987 (drug abuse, pregnancy, and violence) is nonexistent. In 1940, 49 percent of all youth did not finish high school, 37,000 teenagers died from violence or disease, and 335,000 teens gave birth. Educators should discount pastoral memories and…
Sour landfill gas problem solved
Nagl, G.; Cantrall, R.
1996-05-01
In Broward County, Fla., near Pompano Beach, Waste Management of North America (WMNA, a subsidiary of WMX Technologies, Oak Brook, IL) operates the Central Sanitary Landfill and Recycling Center, which includes the country`s largest landfill gas-to-energy plant. The landfill consists of three collection sites: one site is closed, one is currently receiving garbage, and one will open in the future. Approximately 9 million standard cubic feet (scf) per day of landfill gas is collected from approximately 300 wells spread over the 250-acre landfill. With a dramatic increase of sulfur-containing waste coming to a South Florida landfill following Hurricane Andrew, odors related to hydrogen sulfide became a serious problem. However, in a matter of weeks, an innovative desulfurization unit helped calm the landfill operator`s fears. These very high H{sub 2}S concentrations caused severe odor problems in the surrounding residential area, corrosion problems in the compressors, and sulfur dioxide (SO{sub 2}) emission problems in the exhaust gas from the turbine generators.
Coping with School Adaptation Problems
ERIC Educational Resources Information Center
Cowen, Emory L.
1971-01-01
Strategems to cope with maladaptation have been limited in effectiveness. Presented are some key problems they present as well as guidelines for a conceptually preferable set of strategems emphasizing principles which should serve to cut down materially on school maladjustment and restore children to effective school function. (Author/BY)
Problems in unification and supergravity
Farrar, G.; Henyey, F.
1984-01-01
Problems in unification of the various gauge groups, quantum gravity, supersymmetry and supergravity, compact dimensions of space-time, and conditions at the beginning of the universe are discussed. Separate entries were prepared for the data base for the 15 papers presented. (WHK)
RESULTATIVE VERBS AND OTHER PROBLEMS.
ERIC Educational Resources Information Center
HASHIMOTO, ANNE YUE
THE SO-CALLED RESULTATIVE VERBS IN MANDARIN CHINESE ARE STUDIED WITHIN THE GENERAL FRAMEWORK OF A TRANSFORMATIONAL GRAMMAR. THE RESULTATIVE VERBS ARE GENERALLY CONSIDERED AS CONSISTING OF TWO COMPONENTS--A VERBAL COMPONENT FOLLOWED BY A RESULTATIVE OR DIRECTIONAL COMPLEMENT. OTHER PROBLEMS RELATED TO COMPLEMENTS ARE ALSO TOUCHED UPON, FOR EXAMPLE,…
ERIC Educational Resources Information Center
Champagne, Audrey B.; And Others
Teachers in elementary schools, supervisors of instruction, and other educational practitioners are the primary audience for this publication. The paper presents philosophical, psychological, and practical reasons for including a problem-solving approach in elementary school instruction. It draws on the writings of John Dewey, Jean Piaget, James…
Musculoskeletal problems in stroke survivors.
Kendall, Richard
2010-01-01
Musculoskeletal problems in stoke survivors are common reasons for disability and pain. Shoulder pain is present in 24% of stroke survivors among all complications, second only to depression in 26%. Diagnosis and treatment of the various shoulder pain etiologies can significantly improve quality of life in these patients. This article reviews the common etiologies and treatments of shoulder and hip pain in stroke survivors.
Infertility as a psychological problem.
Podolska, Magdalena Z; Bidzan, Mariola
2011-01-01
Recently there has been enormous progress in couple infertility treatment and diagnostics. Some couples cannot conceive despite the fact that there seems to be no objective somatic or immunologic reasons. In such situations gynaecologists are helpless and couples may be overwhelmed by a sense of defeat and hopelessness. Thus, consulting a psychologist or therapist on how to cope better with the problem may be a good solution. The objective of the following paper is to discuss the dilemmas of couples undergoing infertility treatment, related psychological problems, and to determine the need for psychological and therapeutic support. The study demonstrates numerous infertility causes and concludes that there is no universal method of dealing with them. Very frequently psychological and somatic problems overlap. Psychological causes are often the primary factors, but sometimes they are secondary derivatives of the therapeutic process. A wide scope of factors must be considered to attempt psychological analysis of patients treated for infertility including the influence of the family and relations within, reaction to the diagnosis and suggested treatment, the influence of religion on the treatment, the evaluation of the relations in the family of procreation, sexual life assessment, the sense of a woman's self-esteem and self-acceptance. Basing on empirical analysis it was concluded that all women treated for infertility want to create a full family. They have problems in coping with emotional liability during treatment and a sense of fear and failure. Understanding the psychological mechanisms observed in patients treated for infertility might help to diagnose the causes of their problems with facing the new, extremely difficult situation. PMID:21469521
Predicting the Problem Behavior in Adolescents
ERIC Educational Resources Information Center
Karaman, Neslihan G.
2013-01-01
Problem statement: Problem behavior theory describes both protective factors and risk factors to explain adolescent problem behaviors, such as delinquency, alcohol use, and reckless driving. The theory holds that problem behaviors involving risky behavior are used by adolescents as a means to gain peer acceptance and respect. Problem behaviors…
Principles for Teaching Problem Solving. Technical Paper.
ERIC Educational Resources Information Center
Foshay, Rob; Kirkley, Jamie
This Technical Paper focuses on principles for teaching problem solving. Part 1 addresses the need to teach problem solving. Part 2 defines problem solving skills, and describes: general problem solving models of the 1960s and 1970s, current problem solving models, declarative knowledge, mental models, expert versus novice knowledge, procedural…
Anticipating Student Responses to Improve Problem Solving
ERIC Educational Resources Information Center
Wallace, Ann H.
2007-01-01
This article illustrates how problem solving can be enhanced through careful planning and problem presentation. Often, students shut down or are turned off when presented with a problem to solve. The author describes how to motivate students to embrace a problem to be solved and provides helpful prompts to further the problem-solving process.…
Problems on Divisibility of Binomial Coefficients
ERIC Educational Resources Information Center
Osler, Thomas J.; Smoak, James
2004-01-01
Twelve unusual problems involving divisibility of the binomial coefficients are represented in this article. The problems are listed in "The Problems" section. All twelve problems have short solutions which are listed in "The Solutions" section. These problems could be assigned to students in any course in which the binomial theorem and Pascal's…
Word Problems: Where Test Bias Creeps In.
ERIC Educational Resources Information Center
Chipman, Susan F.
The problem of sex bias in mathematics word problems is discussed, with references to the appropriate literature. Word problems are assessed via cognitive science analysis of word problem solving. It has been suggested that five basic semantic relations are adequate to classify nearly all story problems, namely, change, combine, compare, vary, and…
Theoretical and Philosophical Perspectives to Problem Solving.
ERIC Educational Resources Information Center
Sherman, Thomas M.; And Others
1988-01-01
Five articles explore various theoretical aspects of problems and problem solving skills. Highlights include strategies to learn problem solving skills; knowledge structures; metacognition; behavioral processes and cognitive psychology; erotetic logic; creativity as an aspect of computer problem solving; and programing as a problem-solving…
Problems and Promises in Performance Contracting.
ERIC Educational Resources Information Center
Feldmesser, Robert A.
Problems which should be considered in relation to performance contracting include: legal problems, time for planning, teachers' objections, and measuremet problems. Advantages include: the learning experience of planning, Hawthorne effect excitement, and the low cost of this experimentation. (MS)
Problems of indwelling Foley catheters.
Ndirangu, K; Ngugi, M
1994-02-01
One hundred patients undergoing urinary bladder catheterization for various reasons were studied. 42 patients received Sewoon catheters of various sizes. 38 received Eschmann catheters of various sizes and 20 received Bard catheters of various sizes. The duration of catheterization ranged from a few hours to 21 days. Various problems associated with catheterization were recorded whenever encountered. Stuck catheter was found to occur in 15 of the 40 patients who received Sewoon catheters. There were no stuck catheters recorded for Eschmann or Bard catheters. Infections occurred in 9 out of 100 patients, 7 of whom had Sewoon catheters. Leakage was recorded in 12 of the 100 patients, 9 of whom had Sewoon catheters. Blockage of balloon occurred in 5 patients, 3 of whom had Sewoon catheters. Painful spasms occurred in 8 patients, 4 with Bard, 4 with Sewoon catheters. It is concluded that Sewoon type of Foley catheters was associated with more problems than the other types studied.
Laryngeal problems in space travel.
LeJeune, F E
1978-11-01
A start has been made in enumerating possible problems of the larynx, in short or moderately long space voyages, based on our current knowledge of laryngeal diseases. The gravity-free state does not seem to be a threat to the physiology of the larynx. A relatively nonspecialized medical team must be able to recognize and manage Earth-type diseases. They must also be capable of managing both the special problems associated with various degrees of decompression sickness and the increased possibility of inhaling a foreign body, which are inherent in the gravity-free state. In crew selection, a special attempt should be made to eliminate those members with an increased risk of laryngeal disease development. Simplified methods of examining the larynx, including flexible fiberoptic laryngoscopy, should be available. Airway management, including coaxial endotracheal intubation with a bivalved laryngoscope, would be possible. An audiovisual tape library of simple and moderately complex procedures would be highly valuable.
Some nutritional problems of horses.
Hintz, H F; Kallfelz, F A
1981-07-01
The effects of overfeeding, calcium-phosphorus imbalance, misuse of supplements and false advertising on equine nutrition are discussed. Overfeeding is known to cause disorders in several species but, although a similar relationship has been suggested on clinical evidence, no controlled trials on horses have been reported. It has also been suggested that overfeeding is a problem only for those horses with a genetic predisposition to skeletal problems. The importance of adequate calcium and phosphorus levels has been known for many years but severe cases of calcium deficiency still occur. Client education is important and should not be neglected. Excessive use of supplements containing high levels of trace minerals (eg, iodine and selenium) or fat soluble vitamins (eg, vitamin A and vitamin D) can be harmful. Some manufacturers advertise supplements in terms which may inadvertently or intentionally misrepresent their products. Supplements should, therefore, be selected carefully to ensure that they meet the particular requirements of the individual. PMID:7197619
Retrofitting and the mu Problem
Green, Daniel; Weigand, Timo; /SLAC /Stanford U., Phys. Dept.
2010-08-26
One of the challenges of supersymmetry (SUSY) breaking and mediation is generating a {mu} term consistent with the requirements of electro-weak symmetry breaking. The most common approach to the problem is to generate the {mu} term through a SUSY breaking F-term. Often these models produce unacceptably large B{mu} terms as a result. We will present an alternate approach, where the {mu} term is generated directly by non-perturtative effects. The same non-perturbative effect will also retrofit the model of SUSY breaking in such a way that {mu} is at the same scale as masses of the Standard Model superpartners. Because the {mu} term is not directly generated by SUSY breaking effects, there is no associated B{mu} problem. These results are demonstrated in a toy model where a stringy instanton generates {mu}.
Occupational Health Problems of Musicians
Chong, John; Lynden, Melody; Harvey, David; Peebles, Marie
1989-01-01
Musicians, as well as other performing artists, may have their careers interrupted by, interfered with, or terminated by occupational health problems involving the neuro-musculoskeletal system. Adverse working conditions, organization, and activity may affect the health of musicians in all age groups and at all levels of performing ability. Instrument-specific health problems are related to excessive force, static loading, repetitive movement, and duration of musical performance. Important risk factors are 1) change in technique or instrument; 2) intense preparation for a performance; 3) preparation of a new and difficult repertoire; and 4) prolonged periods of performance without rest. Treatment protocols and health promotion or disease prevention programs are being developed in collaboration with the performing arts community. ImagesFigure 1Figure 2Figure 3 PMID:21248930
[Several problems concerning population investment].
Liu, Z
1982-07-29
Population investment is a major topic in the studies of population and economic relations. In this particular area, numerous theoretical and practical problems are still in need of solution. Concerning the problem of population concept, there are three different approaches: (1) to determine the definition of population investment from the relationship between the population growth and the capital from national income used for investment, including investment in the newly increased population and investment in the entire population; (2) to explain population investment from the economic viewpoint that people are producers; and (3) to explain population investment from the expense needed to change a simple labor force to a skillful labor force. The expenses include educational costs, maintanance spending, wages needed to compensate workers in labor, costs for workers to master and learn modern scientific techniques to be used for production, and the costs of keeping a young labor force in the next generation.
Problems in characterizing barrier performance
NASA Technical Reports Server (NTRS)
Jordan, Harry F.
1988-01-01
The barrier is a synchronization construct which is useful in separating a parallel program into parallel sections which are executed in sequence. The completion of a barrier requires cooperation among all executing processes. This requirement not only introduces the wait for the slowest process delay which is inherent in the definition of the synchronization, but also has implications for the efficient implementation and measurement of barrier performance in different systems. Types of barrier implementation and their relationship to different multiprocessor environments are described. Then the problem of measuring the performance of barrier implementations on specific machine architecture is discussed. The fact that the barrier synchronization requires the cooperation of all processes makes the problem of performance measurement similarly global. Making non-intrusive measurements of sufficient accuracy can be tricky on systems offering only rudimentary measurement tools.
An archetype hydrogen atmosphere problem
NASA Technical Reports Server (NTRS)
Athay, R. G.; Mihalas, D.; Shine, R. A.
1975-01-01
Populations for the first three bound states and the continuum of hydrogen are determined for an isothermal hydrostatic atmosphere at 20,000 K. The atmosphere is treated as optically thin in the Balmer and Paschen continua and illuminated by continuum radiation at these wavelengths with prescribed radiation temperatures. The atmosphere is optically thick in the 2-1, 3-1, 3-2 and c-1 transitions. Three stages of approximation are treated: (1) radiative detailed balance in the 2-1, 3-1 and 3-2 transitions, (2) radiative detailed balance in the 3-1 and 3-2 transitions, and (3) all transitions out of detailed balance. The solution of this problem is nontrivial and presents sufficient difficulty to have caused the failure of at least one rather standard technique. The problem is thus a good archetype against which new methods or new implementations of old methods may be tested.
Medical problems from cold exposure
Dembert, M.L.
1982-01-01
Problems resulting from cold exposure can be successfully treated when a coordinated emergency medical transport system and appropriate equipment are available, as well as medical personnel knowledgeable in the management of frostbite and hypothermia. Clinical suspicion of these disorders is essential. Profoundly hypothermic individuals with no recordable vital signs have been resuscitated after controlled, rapid rewarming measures and the use of emergency life-support systems.
On neural connectivity estimation problems.
Baccalá, Luiz A; Sameshima, Koichi
2015-01-01
After briefly recapping and reframing the problem of neural connectivity and its implications for today's brain mapping efforts, we argue that supplementing/replacing traditional conservative correlation based analysis methods requires active user understanding of the aims and limitations of the newly proposed multivariate analysis frameworks before the new methods can gain general acceptance and full profit can be made from the expanded descriptive opportunities they offer. PMID:26737512
Sleep problems in healthy preadolescents.
Kahn, A; Van de Merckt, C; Rebuffat, E; Mozin, M J; Sottiaux, M; Blum, D; Hennart, P
1989-09-01
Few data currently exist concerning the sleep problems of preadolescents. A parent report questionnaire concerning sleep habits and problems was developed. The questionnaires were completed by the parents of 1000 unscreened elementary school children attending the third, fourth, and fifth grades. The schools were randomly selected from an urban area. Of the 1000 questionnaires, 972 were completed and could be used for statistical analysis. Among the parents, 24% reported sleeping poorly and 12% regularly relied on sedatives to induce sleep. Sleep difficulties lasting more than 6 months were present in 43% of the children. In 14% (132 of 972), sleep latency was longer than 30 minutes, and more than one complete arousal occurred during the night at least two nights per week. The following variables were seen among the poor sleepers: lower parental educational and professional status, parents who were more likely to be divorced or separated, and more noise or light in the rooms were they slept. They also presented a higher incidence of somnambulism, somniloquia, and night fears (nightmares and night terrors) than the children who slept well. Boys who slept poorly were significantly more likely to have insomniac fathers (P less than .010). Regular use of sedatives was described in 4% (5 of 132) of the children who slept poorly. Among the "poor sleepers," 21% (33 of 132) had failed 1 or more years at school. School achievement difficulties were encountered significantly more often among the poor sleepers than among the children without sleep problems (P = .001). Of the families with children suffering from sleep problems, 28% expressed a desire for counseling.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2788868
ERIC Educational Resources Information Center
Vautaw, William R.
2008-01-01
We solve two problems that arise when constructing picture frames using only a table saw. First, to cut a cove running the length of a board (given the width of the cove and the angle the cove makes with the face of the board) we calculate the height of the blade and the angle the board should be turned as it is passed over the blade. Second, to…
Inverse Problem of Vortex Reconstruction
NASA Astrophysics Data System (ADS)
Protas, Bartosz; Danaila, Ionut
2014-11-01
This study addresses the following question: given incomplete measurements of the velocity field induced by a vortex, can one determine the structure of the vortex? Assuming that the flow is incompressible, inviscid and stationary in the frame of reference moving with the vortex, the ``structure'' of the vortex is uniquely characterized by the functional relation between the streamfunction and vorticity. To focus attention, 3D axisymmetric vortex rings are considered. We show how this inverse problem can be framed as an optimization problem which can then be efficiently solved using variational techniques. More precisely, we use measurements of the tangential velocity on some contour to reconstruct the function defining the streamfunction-vorticity relation in a continuous setting. Two test cases are presented, involving Hill's and Norbury vortices, in which very good reconstructions are obtained. A key result of this study is the application of our approach to obtain an optimal inviscid vortex model in an actual viscous flow problem based on DNS data which leads to a number of nonintuitive findings.
Benchmark problems in computational aeroacoustics
NASA Technical Reports Server (NTRS)
Porter-Locklear, Freda
1994-01-01
A recent directive at NASA Langley is aimed at numerically predicting principal noise sources. During my summer stay, I worked with high-order ENO code, developed by Dr. Harold Atkins, for solving the unsteady compressible Navier-Stokes equations, as it applies to computational aeroacoustics (CAA). A CAA workshop, composed of six categories of benchmark problems, has been organized to test various numerical properties of code. My task was to determine the robustness of Atkins' code for these test problems. In one category, we tested the nonlinear wave propagation of the code for the one-dimensional Euler equations, with initial pressure, density, and velocity conditions. Using freestream boundary conditions, our results were plausible. In another category, we solved the linearized two-dimensional Euler equations to test the effectiveness of radiation boundary conditions. Here we utilized MAPLE to compute eigenvalues and eigenvectors of the Jacobian given variable and flux vectors. We experienced a minor problem with inflow and outflow boundary conditions. Next, we solved the quasi one dimensional unsteady flow equations with an incoming acoustic wave of amplitude 10(exp -6). The small amplitude sound wave was incident on a convergent-divergent nozzle. After finding a steady-state solution and then marching forward, our solution indicated that after 30 periods the acoustic wave had dissipated (a period is time required for sound wave to traverse one end of nozzle to other end).
Health disparities: reframing the problem.
Fuller, Kathleen E
2003-03-01
Health disparities are of continuing concern to the community of public health professionals. Despite concerted efforts on a number of fronts, little progress seems to have been made towards eliminating these disparities. This is due in part to a frame of reference that focuses on race and racism. While racism plays a role, continued focus on socially constructed racial groups will not lead to solutions to the problem. Humans are biological organisms and the presence of disease indicates a maladaptation between the individual human organism and its environment. Lumping together into a 'racial' group large numbers of individuals who share little in terms of phenotype, culture, and/or behavior inhibits reaching appropriate solutions. Progress will only be made when the issue of health disparities is reframed as one of phenotype/environmental mismatch. Such a frame crosscuts current racial groups. Health disparities such as hypertension, prostate cancer, low-birth-weight (LBW) infants, infant mortality, rickets, and melanoma are affected by the interactions of degree of pigmentation, amount of exposure to ultraviolet B (UVB) radiation, and levels of serum vitamin D. Reframing the problem of health disparities from one of race and racism to one of phenotype/environmental mismatch permits a solution to an otherwise intractable problem.
Node weighted network upgrade problems
Krumke, S.O.; Noltemeier, H.; Marathe, M.V.; Ravi, S.S.
1996-09-01
Consider a network where nodes represent processors and edges represent bidirectional communication links. The processor at a node v can be upgraded at an expense of cost(v). Such an upgrade reduces the delay of each link emanating from v by a fixed factor x, where 0 < x < 1. The goal is to find a minimum cost set of nodes to be upgraded so that the resulting network has a spanning tree in which edge is of delay at most a given value {delta}. The authors provide both hardness and approximation results for the problem. They show that the problem is NP-hard and cannot be approximated within any factor {beta} < ln n, unless NP {improper_subset} DTIME(n{sup log log n}), where n is the number of nodes in the network. They then present the first polynomial time approximation algorithms for the problem. For the general case, the approximation algorithm comes within a factor of 2 ln n of the minimum upgrading cost. When the cost of upgrading each node is 1, they present an approximation algorithm with a performance guarantee of 4(2 + ln {Delta}), where {Delta} is the maximum node degree. Finally, they present a polynomial time algorithm for the class of treewidth-bounded graphs.
Acid deposition: a national problem
Hendrey, G.R.
1985-01-01
The deposition of excessive quantities of sulfur and nitrogen from the atmosphere constitutes a problem encompassing all of the United States east of the Mississippi River. It also occurs in some areas of the western US. Calculations based on emission inventories and simplifying assumptions indicate electric utilities account for 66% of SO/sub 2/ emissions, 29% of NO/sub x/ emissions and about half of precipitation acidity. Acidification of clearwater lakes and streams is a widespread problem only in areas receiving rain with an average acidity less than or equal to 4.7. The dominant anion in such waters is SO/sub 4//sup 2 -/ and concentrations of aluminum derived from watershed acidification may exceed 200 ..mu..g 1/sup -1/. Changes in assemblages of aquatic biota become increasingly apparent as pH decreases below 6.0, and elimination of fish from some waters has been documented. The sensitivity of surface waters is controlled by and represents an integration of biogeochemical processes in their edaphic settings. Changes in surface water chemistry imply changes in the terrestrial environment. Direct evidence of changes in terrestrial environments is sparse. Nevertheless, observations of forest dieback in the US and abroad suggest that acid deposition may contribute to the problem. Very few credible studies are available which allow an evaluation of acid precipitation effects on crops.
Whither the global population problem.
Greep, R O
1998-02-15
Growth of the human population has been underway for thousands of years and was never a problem until recently. It is now expanding exponentially, and today global population stands at nearly 6 billion with 97 million being added each year. Currently, overpopulation has led to serious social and environmental problems such as poverty, overcrowded slums, crime, terrorism, pollution of air and water, and depletion of the protective ozone layer. Warnings were sounded, but few listened. The enthusiasm once generated for solving the problem of too many people was short-lived. The press with puzzling abrogation of its responsibility to the public managed to allay all fears of population overgrowth. Two U.S. presidents welcomed such growth as a stimulus to economic development. Although modern contraceptives are safe, effective, and widely available, more are badly needed, but none are in the pipeline. Research is being hampered by hostile attitudes and by the high cost in time and money of bringing a new contraceptive to an uncertain market with the added threat of litigation. At the present rate of growth, the population will double in the next century. This is believed to be beyond the carrying capacity of our planet. Corrective measures by man or nature need to be undertaken.
Benchmark problems in computational aeroacoustics
NASA Astrophysics Data System (ADS)
Porter-Locklear, Freda
1994-12-01
A recent directive at NASA Langley is aimed at numerically predicting principal noise sources. During my summer stay, I worked with high-order ENO code, developed by Dr. Harold Atkins, for solving the unsteady compressible Navier-Stokes equations, as it applies to computational aeroacoustics (CAA). A CAA workshop, composed of six categories of benchmark problems, has been organized to test various numerical properties of code. My task was to determine the robustness of Atkins' code for these test problems. In one category, we tested the nonlinear wave propagation of the code for the one-dimensional Euler equations, with initial pressure, density, and velocity conditions. Using freestream boundary conditions, our results were plausible. In another category, we solved the linearized two-dimensional Euler equations to test the effectiveness of radiation boundary conditions. Here we utilized MAPLE to compute eigenvalues and eigenvectors of the Jacobian given variable and flux vectors. We experienced a minor problem with inflow and outflow boundary conditions. Next, we solved the quasi one dimensional unsteady flow equations with an incoming acoustic wave of amplitude 10(exp -6). The small amplitude sound wave was incident on a convergent-divergent nozzle. After finding a steady-state solution and then marching forward, our solution indicated that after 30 periods the acoustic wave had dissipated (a period is time required for sound wave to traverse one end of nozzle to other end).
Algorithmic Perspectives on Problem Formulations in MDO
NASA Technical Reports Server (NTRS)
Alexandrov, Natalia M.; Lewis, Robert Michael
2000-01-01
This work is concerned with an approach to formulating the multidisciplinary optimization (MDO) problem that reflects an algorithmic perspective on MDO problem solution. The algorithmic perspective focuses on formulating the problem in light of the abilities and inabilities of optimization algorithms, so that the resulting nonlinear programming problem can be solved reliably and efficiently by conventional optimization techniques. We propose a modular approach to formulating MDO problems that takes advantage of the problem structure, maximizes the autonomy of implementation, and allows for multiple easily interchangeable problem statements to be used depending on the available resources and the characteristics of the application problem.
Context in Mathematics Learning: Problems and Possibilities
ERIC Educational Resources Information Center
Lee, Ji-Eun
2007-01-01
This article presents an instructional idea that facilitates the students' active participation in the problem analysis process using insufficient or contradictory problem contexts. (Contains 1 figure.)
Fibonacci's Triangle: A Vehicle for Problem Solving.
ERIC Educational Resources Information Center
Ouellette, Hugh
1979-01-01
A method for solving certain types of problems is illustrated by problems related to Fibonacci's triangle. The method involves pattern recognition, generalizing, algebraic manipulation, and mathematical induction. (MP)
Authentication: A Standard Problem or a Problem of Standards?
2016-01-01
Reproducibility and transparency in biomedical sciences have been called into question, and scientists have been found wanting as a result. Putting aside deliberate fraud, there is evidence that a major contributor to lack of reproducibility is insufficient quality assurance of reagents used in preclinical research. Cell lines are widely used in biomedical research to understand fundamental biological processes and disease states, yet most researchers do not perform a simple, affordable test to authenticate these key resources. Here, we provide a synopsis of the problems we face and how standards can contribute to an achievable solution. PMID:27300550
Multigrid Methods for EHL Problems
NASA Technical Reports Server (NTRS)
Nurgat, Elyas; Berzins, Martin
1996-01-01
In many bearings and contacts, forces are transmitted through thin continuous fluid films which separate two contacting elements. Objects in contact are normally subjected to friction and wear which can be reduced effectively by using lubricants. If the lubricant film is sufficiently thin to prevent the opposing solids from coming into contact and carries the entire load, then we have hydrodynamic lubrication, where the lubricant film is determined by the motion and geometry of the solids. However, for loaded contacts of low geometrical conformity, such as gears, rolling contact bearings and cams, this is not the case due to high pressures and this is referred to as Elasto-Hydrodynamic Lubrication (EHL) In EHL, elastic deformation of the contacting elements and the increase in fluid viscosity with pressure are very significant and cannot be ignored. Since the deformation results in changing the geometry of the lubricating film, which in turn determines the pressure distribution, an EHL mathematical model must simultaneously satisfy the complex elasticity (integral) and the Reynolds lubrication (differential) equations. The nonlinear and coupled nature of the two equations makes numerical calculations computationally intensive. This is especially true for highly loaded problems found in practice. One novel feature of these problems is that the solution may exhibit sharp pressure spikes in the outlet region. To this date both finite element and finite difference methods have been used to solve EHL problems with perhaps greater emphasis on the use of the finite difference approach. In both cases, a major computational difficulty is ensuring convergence of the nonlinear equations solver to a steady state solution. Two successful methods for achieving this are direct iteration and multigrid methods. Direct iteration methods (e.g Gauss Seidel) have long been used in conjunction with finite difference discretizations on regular meshes. Perhaps one of the best examples of
[Addiction therapy. Limits, problems, perspectives].
Kalapos, Miklós Péter
2014-01-01
In health care, tending is a process, which offers for the patients a continuous watching on, a control, a treatment, and the prevention of worsening of their medical status as well as the reduction of their complaints. In the article, some fundamental segments of tending in addictology are reviewed, particularly paying attention to whom, how, where and how long to take care. On the basis of literature, the author stresses whatever method is used to treat addict patients it is more beneficial to society than the avoidance of any intervention due to the negligence of the problem. Addictology has lost a lot from its power in Hungary. The author recommends the introduction of the methods of health quality assurance to decrease the effect of negative trends seen in addictology. The paper also deals with special patient groups including homeless clients, adolescents, elderly and pregnant patients as well as health care professionals. The author critically mentions the double communication of society, the dual-face character of politics and has the opinion that competences are not clear making the situation confused. As a mistake of the point of view is it regarded that the addictological problems are classified as to belonging to the authority of psychiatry. It is emphasized that multidisciplinary approach is needed to understand the problem and to treat the client. General screening for addictological diseases does not seem possible in the light of low capacity of the system, but the screening of adolescents and pregnant women is definitely recommended. And finally, a financial support for medicines to prevent craving, a moratorium for the continuous changing of rules and law, the sponsoring of harm reduction programs as well as a better utilization of opportunities offered by local drug coordinating boards are proposed.
Genetics problem solving and worldview
NASA Astrophysics Data System (ADS)
Dale, Esther
The research goal was to determine whether worldview relates to traditional and real-world genetics problem solving. Traditionally, scientific literacy emphasized content knowledge alone because it was sufficient to solve traditional problems. The contemporary definition of scientific literacy is, "The knowledge and understanding of scientific concepts and processes required for personal decision-making, participation in civic and cultural affairs and economic productivity" (NRC, 1996). An expanded definition of scientific literacy is needed to solve socioscientific issues (SSI), complex social issues with conceptual, procedural, or technological associations with science. Teaching content knowledge alone assumes that students will find the scientific explanation of a phenomenon to be superior to a non-science explanation. Formal science and everyday ways of thinking about science are two different cultures (Palmer, 1999). Students address this rift with cognitive apartheid, the boxing away of science knowledge from other types of knowledge (Jedege & Aikenhead, 1999). By addressing worldview, cognitive apartheid may decrease and scientific literacy may increase. Introductory biology students at the University of Minnesota during fall semester 2005 completed a written questionnaire-including a genetics content-knowledge test, four genetic dilemmas, the Worldview Assessment Instrument (WAI) and some items about demographics and religiosity. Six students responded to the interview protocol. Based on statistical analysis and interview data, this study concluded the following: (1) Worldview, in the form of metaphysics, relates to solving traditional genetic dilemmas. (2) Worldview, in the form of agency, relates to solving traditional genetics problems. (3) Thus, worldview must be addressed in curriculum, instruction, and assessment.
The Hard Problem of Cooperation
Eriksson, Kimmo; Strimling, Pontus
2012-01-01
Based on individual variation in cooperative inclinations, we define the “hard problem of cooperation” as that of achieving high levels of cooperation in a group of non-cooperative types. Can the hard problem be solved by institutions with monitoring and sanctions? In a laboratory experiment we find that the answer is affirmative if the institution is imposed on the group but negative if development of the institution is left to the group to vote on. In the experiment, participants were divided into groups of either cooperative types or non-cooperative types depending on their behavior in a public goods game. In these homogeneous groups they repeatedly played a public goods game regulated by an institution that incorporated several of the key properties identified by Ostrom: operational rules, monitoring, rewards, punishments, and (in one condition) change of rules. When change of rules was not possible and punishments were set to be high, groups of both types generally abided by operational rules demanding high contributions to the common good, and thereby achieved high levels of payoffs. Under less severe rules, both types of groups did worse but non-cooperative types did worst. Thus, non-cooperative groups profited the most from being governed by an institution demanding high contributions and employing high punishments. Nevertheless, in a condition where change of rules through voting was made possible, development of the institution in this direction was more often voted down in groups of non-cooperative types. We discuss the relevance of the hard problem and fit our results into a bigger picture of institutional and individual determinants of cooperative behavior. PMID:22792282
NASA Astrophysics Data System (ADS)
Feulner, Georg
2012-05-01
For more than four decades, scientists have been trying to find an answer to one of the most fundamental questions in paleoclimatology, the “faint young Sun problem.” For the early Earth, models of stellar evolution predict a solar energy input to the climate system that is about 25% lower than today. This would result in a completely frozen world over the first 2 billion years in the history of our planet if all other parameters controlling Earth's climate had been the same. Yet there is ample evidence for the presence of liquid surface water and even life in the Archean (3.8 to 2.5 billion years before present), so some effect (or effects) must have been compensating for the faint young Sun. A wide range of possible solutions have been suggested and explored during the last four decades, with most studies focusing on higher concentrations of atmospheric greenhouse gases like carbon dioxide, methane, or ammonia. All of these solutions present considerable difficulties, however, so the faint young Sun problem cannot be regarded as solved. Here I review research on the subject, including the latest suggestions for solutions of the faint young Sun problem and recent geochemical constraints on the composition of Earth's early atmosphere. Furthermore, I will outline the most promising directions for future research. In particular I would argue that both improved geochemical constraints on the state of the Archean climate system and numerical experiments with state-of-the-art climate models are required to finally assess what kept the oceans on the Archean Earth from freezing over completely.
[Addiction therapy. Limits, problems, perspectives].
Kalapos, Miklós Péter
2014-01-01
In health care, tending is a process, which offers for the patients a continuous watching on, a control, a treatment, and the prevention of worsening of their medical status as well as the reduction of their complaints. In the article, some fundamental segments of tending in addictology are reviewed, particularly paying attention to whom, how, where and how long to take care. On the basis of literature, the author stresses whatever method is used to treat addict patients it is more beneficial to society than the avoidance of any intervention due to the negligence of the problem. Addictology has lost a lot from its power in Hungary. The author recommends the introduction of the methods of health quality assurance to decrease the effect of negative trends seen in addictology. The paper also deals with special patient groups including homeless clients, adolescents, elderly and pregnant patients as well as health care professionals. The author critically mentions the double communication of society, the dual-face character of politics and has the opinion that competences are not clear making the situation confused. As a mistake of the point of view is it regarded that the addictological problems are classified as to belonging to the authority of psychiatry. It is emphasized that multidisciplinary approach is needed to understand the problem and to treat the client. General screening for addictological diseases does not seem possible in the light of low capacity of the system, but the screening of adolescents and pregnant women is definitely recommended. And finally, a financial support for medicines to prevent craving, a moratorium for the continuous changing of rules and law, the sponsoring of harm reduction programs as well as a better utilization of opportunities offered by local drug coordinating boards are proposed. PMID:25411227
Scale problem in wormhole physics
Kim, J. E.; Lee, K.
1989-07-03
Wormhole physics from the quantum thoery of gravity coupled to the second-rank antisymmetric tensor or Goldstone-boson fields leads to an effective potential for these fields. The cosmological energy-density bound is shown to put an upper bound on the cosmological constant which wormhole physics can make zero. This upper bound, of order 10/sup 11/ GeV, is far smaller than the Planck scale and barely compatible with the possible cosmological constant arising from grand unified theories. In addition, the effect of wormholes on the axion for the strong /ital CP/ problem is discussed.
The Born transmission eigenvalue problem
NASA Astrophysics Data System (ADS)
Cakoni, Fioralba; Colton, David; Rezac, Jacob D.
2016-10-01
In this paper we study the distribution of transmission eigenvalues in the complex plane for obstacles whose contrast is small in magnitude. We use a first order approximation of the refractive index to derive and study an approximate interior transmission problem. In the case of spherically stratified media, we prove existence and discreteness of transmission eigenvalues and derive a condition under which the complex part of transmission eigenvalues cannot lie in a strip parallel to the real axis. For obstacles with general shape, we demonstrate that if transmission eigenvalues exist then they form a discrete set.
Solving the Dark Matter Problem
Baltz, Ted
2016-07-12
Cosmological observations have firmly established that the majority of matter in the universe is of an unknown type, called 'dark matter'. A compelling hypothesis is that the dark matter consists of weakly interacting massive particles (WIMPs) in the mass range around 100 GeV. If the WIMP hypothesis is correct, such particles could be created and studied at accelerators. Furthermore they could be directly detected as the primary component of our galaxy. Solving the dark matter problem requires that the connection be made between the two. We describe some theoretical and experimental avenues that might lead to this connection.
Diagnostic problems in oral pathology.
Dunlap, C L; Barker, B F
1985-02-01
Diagnostic problems within the oral cavity may be associated with lesions of the odontogenic apparatus, salivary glands, bone, mucosa, and connective tissue. Some lesions are unique to the oral cavity, others have a systemic distribution. Several unique and controversial lesions have been selected for discussion, including (1) necrotizing sialometaplasia, a benign salivary gland disease easily mistaken for malignancy; (2) verrucous lesions including verrucous carcinoma, verrucous hyperplasia, and papillary carcinoma; (3) spindle-cell carcinoma, which is often confused with sarcoma; (4) named and unnamed embryonic rests, which may resemble metastatic carcinomas; (5) dental pulp mistaken for odontogenic myxoma; and (6) granular cell tumor with associated pseudoepitheliomatous hyperplasia.
Elementary Level Mathematics: Word Problems. Second Edition
ERIC Educational Resources Information Center
Mosrur, Ridwanul
2011-01-01
Word Problems those are also named as "Story Problems" which are well known to the students around the world. In this book there are 26 chapters which encompass diversified problems of four basic mathematical rules--addition, subtraction, multiplication and division. These problems may help students to practice more and more as well as may help…
Tour of a Simple Trigonometry Problem
ERIC Educational Resources Information Center
Poon, Kin-Keung
2012-01-01
This article focuses on a simple trigonometric problem that generates a strange phenomenon when different methods are applied to tackling it. A series of problem-solving activities are discussed, so that students can be alerted that the precision of diagrams is important when solving geometric problems. In addition, the problem-solving plan was…
Journey toward Teaching Mathematics through Problem Solving
ERIC Educational Resources Information Center
Sakshaug, Lynae E.; Wohlhuter, Kay A.
2010-01-01
Teaching mathematics through problem solving is a challenge for teachers who learned mathematics by doing exercises. How do teachers develop their own problem solving abilities as well as their abilities to teach mathematics through problem solving? A group of teachers began the journey of learning to teach through problem solving while taking a…
Toward a Design Theory of Problem Solving.
ERIC Educational Resources Information Center
Jonassen, David H.
2000-01-01
Proposes a metatheory of problem solving. Describes differences among problems in terms of their structured ness, domain specificity (abstractness), and complexity; describes individual differences that affect problem solving; and presents a typology of problems, each of which engages different cognitive, affective, and conative process and…
Disciplinary Foundations for Solving Interdisciplinary Scientific Problems
ERIC Educational Resources Information Center
Zhang, Dongmei; Shen, Ji
2015-01-01
Problem-solving has been one of the major strands in science education research. But much of the problem-solving research has been conducted on discipline-based contexts; little research has been done on how students, especially individuals, solve interdisciplinary problems. To understand how individuals reason about interdisciplinary problems, we…
King Oedipus and the Problem Solving Process.
ERIC Educational Resources Information Center
Borchardt, Donald A.
An analysis of the problem solving process reveals at least three options: (1) finding the cause, (2) solving the problem, and (3) anticipating potential problems. These methods may be illustrated by examining "Oedipus Tyrannus," a play in which a king attempts to deal with a problem that appears to be beyond his ability to solve, and applying…
The 4-Weight Problem -- A Pedagogical Account.
ERIC Educational Resources Information Center
Hadar, Nitsa; Hadass, Rina
1982-01-01
The Weight Problem of Bachet de Meziriac is described, which looks for four integral weights to measure every amount between one and forty kilograms. Discussed are generalizations of the problem and analogous problems, solutions of particular cases, and a solution of the general problem. (MP)
"Seed Problems" in the Teaching of Mathematics.
ERIC Educational Resources Information Center
McLoughlin, Patrick
1987-01-01
The technique of using "seed problems" involves starting with a simple problem and seeing how far it leads. It may inspire different, related problems, or it may be approached with varied tools. Problems related to points and lines, pyramids, Pythagorean quadruples, and regular pentagons are discussed. (MNS)
Problem Posing with the Multiplication Table
ERIC Educational Resources Information Center
Dickman, Benjamin
2014-01-01
Mathematical problem posing is an important skill for teachers of mathematics, and relates readily to mathematical creativity. This article gives a bit of background information on mathematical problem posing, lists further references to connect problem posing and creativity, and then provides 20 problems based on the multiplication table to be…
Enhanced Student Learning with Problem Based Learning
ERIC Educational Resources Information Center
Hollenbeck, James
2008-01-01
Science educators define a learning environment in which the problem drives the learning as problem based learning (PBL). Problem based learning can be a learning methodology/process or a curriculum based on its application by the teacher. This paper discusses the basic premise of Problem base learning and successful applications of such learning.…
Problem-elephant translocation: translocating the problem and the elephant?
Fernando, Prithiviraj; Leimgruber, Peter; Prasad, Tharaka; Pastorini, Jennifer
2012-01-01
Human-elephant conflict (HEC) threatens the survival of endangered Asian elephants (Elephas maximus). Translocating "problem-elephants" is an important HEC mitigation and elephant conservation strategy across elephant range, with hundreds translocated annually. In the first comprehensive assessment of elephant translocation, we monitored 16 translocations in Sri Lanka with GPS collars. All translocated elephants were released into national parks. Two were killed within the parks where they were released, while all the others left those parks. Translocated elephants showed variable responses: "homers" returned to the capture site, "wanderers" ranged widely, and "settlers" established home ranges in new areas soon after release. Translocation caused wider propagation and intensification of HEC, and increased elephant mortality. We conclude that translocation defeats both HEC mitigation and elephant conservation goals.
Applying optimization software libraries to engineering problems
NASA Technical Reports Server (NTRS)
Healy, M. J.
1984-01-01
Nonlinear programming, preliminary design problems, performance simulation problems trajectory optimization, flight computer optimization, and linear least squares problems are among the topics covered. The nonlinear programming applications encountered in a large aerospace company are a real challenge to those who provide mathematical software libraries and consultation services. Typical applications include preliminary design studies, data fitting and filtering, jet engine simulations, control system analysis, and trajectory optimization and optimal control. Problem sizes range from single-variable unconstrained minimization to constrained problems with highly nonlinear functions and hundreds of variables. Most of the applications can be posed as nonlinearly constrained minimization problems. Highly complex optimization problems with many variables were formulated in the early days of computing. At the time, many problems had to be reformulated or bypassed entirely, and solution methods often relied on problem-specific strategies. Problems with more than ten variables usually went unsolved.
Animal mindreading: what's the problem?
Heyes, Cecilia
2015-04-01
Research on mindreading in animals has the potential to address fundamental questions about the nature and origins of the human capacity to ascribe mental states, but it is a research programme that seems to be in trouble. Between 1978 and 2000 several groups used a range of methods, some with considerable promise, to ask whether animals can understand a variety of mental states. Since that time, many enthusiasts have become sceptics, empirical methods have become more limited, and it is no longer clear what research on animal mindreading is trying to find. In this article I suggest that the problems are theoretical and methodological: there is difficulty in conceptualising alternatives to 'full-blown' mindreading, and reluctance to use the kinds of empirical methods necessary to distinguish mindreading from other psychological mechanisms. I also suggest ways of tackling the theoretical and methodological problems that draw on recent studies of mindreading in humans, and the resources of experimental psychology more generally. In combination with the use of inanimate control stimuli, species that are unlikely to be capable of mindreading, and the 'goggles method', these approaches could restore both vigour and rigour to research on animal mindreading. PMID:25102928
Cellulase recovery: Problems and potential
Woodward, J.; Lee, N.E.
1989-01-01
The enzymatic hydrolysis of cellulose may become commercially feasible if the enzyme is recovered and reused. The use of immobilized cellobiohydrolase (CBH) and endoglucanase (EG) does not appear feasible since the substrate itself is insoluble. Since the ..beta..-glucosidase (BG) component of cellulase acts upon soluble substrates it has the potential to be immobilized, used, and reused in this form. The problem of CBH and EG recovery has been tackled by examining their ability to be adsorbed to inorganically-based kieselguhr Macrosorb granules which can be used repeatedly for cellulase adsorption. The kinetics of the adsorption of Trichoderma reesei C30 cellulase protein to DEAE-Macrosorb are described and these Macrosorb particles have been used to recover cellulase from Avicel and steam-exploded aspen wood hydrolysates. The problem of ..beta..-glucosidase recovery could be achieved by immobilizing it onto an affinity material such as concanavalin A from which this enzyme is difficult to elute. Cellulase adsorbed onto lignocellulosic residues at the completion of hydrolysis can be eluted from the residue using a protein denaturant. Reactivation of the denatured enzyme may be possible. 19 refs., 1 fig., 3 tabs.
Meng Guowu
2009-07-15
Let n{>=}2 be a positive integer. To each irreducible representation {sigma} of Sp(1), an Sp(1)-Kepler problem in dimension (4n-3) is constructed and analyzed. This system is superintegrable, and when n=2 it is equivalent to a generalized MICZ-Kepler problem in dimension of 5. The dynamical symmetry group of this system is O-tilde*(4n) with the Hilbert space of bound states H({sigma}) being the unitary highest weight representation of O*-tilde(4n) with highest weight, (-1,{center_dot}{center_dot}{center_dot},-1,-(1+{sigma})), which occurs at the rightmost nontrivial reduction point in the Enright-Howe-Wallach classification diagram for the unitary highest weight modules. Here {sigma} is the highest weight of {sigma}. Furthermore, it is shown that the correspondence {sigma}{r_reversible}H({sigma}) is the theta-correspondence for dual pair (Sp(1),O*(4n))subset Sp(8n,R)
Temperament: concepts, issues and problems.
Rutter, M
1982-01-01
There are marked individual differences in children's temperamental styles-- differences thought to be constitutionally determined in part. The importance of temperamental features is evident in their links with various forms of psychopathology and in their effects on the manner in which other people respond to the child. For these and other reasons it has rightly come to be accepted that greater attention needs to be paid to temperamental issues in consideration of the processes of development, children's responses to stress situations, and the genesis of emotional, behavioural and learning disorders. However, major conceptual, methodological and theoretical problems remain. Problems of measurement are considered in terms of the relativity of measures, whether or not to take social context into account, the functional equivalence of measures at different ages, the circumstances to use in assessing temperament, the choice of measuring instrument and the categorization of temperamental features. The issues involved in the meaning of temperamental differences are discussed with respect to consistency, developmental change, genetic influences, brain damage and mental retardation, sex differences and the mechanisms by which temperamental variables exert their effects.
Community-powered problem solving.
Gouillart, Francis; Billings, Douglas
2013-04-01
Traditionally, companies have managed their constituencies with specific processes: marketing to customers, procuring from vendors, developing HR policies for employees, and so on. The problem is, such processes focus on repeatability and compliance, so they can lead to stagnation. Inviting your constituencies to collectively help you solve problems and exploit opportunities--"co-creation"--is a better approach. It allows you to continually tap the skills and insights of huge numbers of stakeholders and develop new ways to produce value for all. The idea is to provide stakeholders with platforms (physical and digital forums) on which they can interact, get them to start exploring new experiences and connections, and let the system grow organically. A co-creation initiative by a unit of Becton, Dickinson and Company demonstrates how this works. A global leader in syringes, BD set out to deepen its ties with hospital customers and help them reduce the incidence of infections from unsafe injection and syringe disposal practices. The effort began with a cross-functional internal team, brought in the hospital procurement and supply managers BD had relationships with, and then reached out to hospitals' infection-prevention and occupational health leaders. Eventually product designers, nurses, sustainability staffers, and even hospital CFOs were using the platform, contributing data that generated new best practices and reduced infections.
Community-powered problem solving.
Gouillart, Francis; Billings, Douglas
2013-04-01
Traditionally, companies have managed their constituencies with specific processes: marketing to customers, procuring from vendors, developing HR policies for employees, and so on. The problem is, such processes focus on repeatability and compliance, so they can lead to stagnation. Inviting your constituencies to collectively help you solve problems and exploit opportunities--"co-creation"--is a better approach. It allows you to continually tap the skills and insights of huge numbers of stakeholders and develop new ways to produce value for all. The idea is to provide stakeholders with platforms (physical and digital forums) on which they can interact, get them to start exploring new experiences and connections, and let the system grow organically. A co-creation initiative by a unit of Becton, Dickinson and Company demonstrates how this works. A global leader in syringes, BD set out to deepen its ties with hospital customers and help them reduce the incidence of infections from unsafe injection and syringe disposal practices. The effort began with a cross-functional internal team, brought in the hospital procurement and supply managers BD had relationships with, and then reached out to hospitals' infection-prevention and occupational health leaders. Eventually product designers, nurses, sustainability staffers, and even hospital CFOs were using the platform, contributing data that generated new best practices and reduced infections. PMID:23593769
Dermatological problems of the puberty
Brzezińska-Wcisło, Ligia
2013-01-01
Puberty is a period of life between childhood and adulthood. It is characterized by many changes in morphology and appearance of the body (biological maturation), in the psyche – development of personality (psychological maturation), and in the attitude towards one's own and the opposite sex (psychosexual maturation), and in the social role (social maturation). Dermatological problems of adolescence are mainly related to fluctuations in hormone levels, mainly androgens. They include acne, hair problems and excessive sweating. Acne vulgaris is the most frequently diagnosed dermatosis in patients aged between 11 and 30 years. It is believed that it affects about 80% of persons in this age group or even, taking into account lesions of low intensity, 100% of young people. Excessive sweating is a condition characterised by excessive production of sweat, resulting from high activity of sweat glands. The sweat glands are localised in almost all areas of the body surface but on the hands, feet, armpits and around the groin they are found at the highest density. Seborrhoeic dermatitis of the scalp is a chronic, relapsing, inflammatory dermatosis, which currently affects about 5% of the population. It affects mostly young people, particularly men. PMID:24278071
Wang Shuang; Li Xiaodong; Li Miao
2010-11-15
We investigate the cosmic age problem associated with 9 extremely old globular clusters in M31 galaxy and 1 very old high-z quasar automatic plate-measuring machine 08279+5255 at z=3.91. These 9 globular clusters have not been used to study the cosmic age problem in the previous literature. By evaluating the age of the Universe in the {Lambda} cold dark matter model with the observational constraints from the Type Ia supernovae, the baryon acoustic oscillations, the cosmic microwave background, and the independent H{sub 0} measurements, we find that the existence of 5 globular clusters and 1 high-z quasar are in tension (over 2{sigma} confidence level) with the current cosmological observations. So if the age estimates of these objects are correct, the cosmic age puzzle still remains in the standard cosmology. Moreover, we extend our investigations to the cases of the interacting dark energy models. It is found that although the introduction of the interaction between dark sectors can give a larger cosmic age, the interacting dark energy models still have difficulty to pass the cosmic age test.