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.
Renormalization-group study of the four-body problem
Schmidt, Richard; Moroz, Sergej
2010-05-15
We perform a renormalization-group analysis of the nonrelativistic four-boson problem by means of a simple model with pointlike three- and four-body interactions. We investigate in particular the region where the scattering length is infinite and all energies are close to the atom threshold. We find that the four-body problem behaves truly universally, independent of any four-body parameter. Our findings confirm the recent conjectures of others that the four-body problem is universal, now also from a renormalization-group perspective. We calculate the corresponding relations between the four- and three-body bound states, as well as the full bound-state spectrum and comment on the influence of effective range corrections.
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.
NASA Astrophysics Data System (ADS)
Bakker, Lennard F.; Ouyang, Tiancheng; Yan, Duokui; Simmons, Skyler; Roberts, Gareth E.
2010-10-01
We apply the analytic-numerical method of Roberts to determine the linear stability of time-reversible periodic simultaneous binary collision orbits in the symmetric collinear four-body problem with masses 1, m, m, 1, and also in a symmetric planar four-body problem with equal masses. In both problems, the assumed symmetries reduce the determination of linear stability to the numerical computation of a single real number. For the collinear problem, this verifies the earlier numerical results of Sweatman for linear stability with respect to collinear and symmetric perturbations.
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.
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.
Families of three-dimensional periodic solutions in the circular restricted four-body problem
NASA Astrophysics Data System (ADS)
Papadakis, K. E.
2016-04-01
In this paper we study the 3D symmetric periodic orbits of the circular restricted four-body problem, through their bifurcation from plane orbits. To this end, we calculate the special generating planar periodic orbits, i.e. the vertical-critical orbits, from five basic planar families of symmetric periodic orbits of the problem. We study the simplest 3D periodic orbits and so we restrict our calculations to simple vertical bifurcation orbits leading to families of one or two revolutions three-dimensional symmetric periodic orbits. We found 21 such families of simple 3D symmetric periodic orbits and typical orbits of all symmetry type 3D orbits are presented. The stability of each calculated 3D periodic orbit is also studied. Characteristic curves as well as stability diagrams of families of 3D periodic orbits are illustrated.
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
Transfer orbits to/from the Lagrangian points in the restricted four-body problem
NASA Astrophysics Data System (ADS)
Cabette, Regina Elaine Santos; Prado, Antonio F. B. A.
2008-12-01
The well-known Lagrangian points that appear in the planar restricted three-body problem are very important for astronautical applications. They are five points of equilibrium in the equations of motion, what means that a particle located at one of those points with zero velocity will remain there indefinitely. The collinear points ( L1, L2 and L3) are always unstable and the triangular points ( L4 and L5) are stable in the present case studied (Earth-Sun system). They are all very good points to locate a space-station, since they require a small amount of ΔV (and fuel), the control to be used, for station-keeping. The triangular points are especially good for this purpose, since they are stable equilibrium points. In this paper, the planar restricted four-body problem applied to the Sun-Earth-Moon-Spacecraft is combined with numerical integration and gradient methods to solve the two-point boundary value problem. This combination is applied to the search of families of transfer orbits between the Lagrangian points and the Earth, in the Earth-Sun system, with the minimum possible cost of the control used. So, the final goal of this paper is to find the magnitude of the two impulses to be applied in the spacecraft to complete the transfer: the first one when leaving/arriving at the Lagrangian point and the second one when arriving/living at the Earth. The dynamics given by the restricted four-body problem is used to obtain the trajectory of the spacecraft, but not the position of the equilibrium points. Their position is taken from the restricted three-body model. The goal to use this model is to evaluate the perturbation of the Sun in those important trajectories, in terms of fuel consumption and time of flight. The solutions will also show how to apply the impulses to accomplish the transfers under this force model. The results showed a large collection of transfers, and that there are initial conditions (position of the Sun with respect to the other bodies
Study of lunar gravity assist orbits in the restricted four-body problem
NASA Astrophysics Data System (ADS)
Qi, Yi; Xu, Shijie
2016-04-01
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.
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.
Absence of a four-body Efimov effect in the 2 +2 fermionic problem
NASA Astrophysics Data System (ADS)
Endo, Shimpei; Castin, Yvan
2015-11-01
In the free three-dimensional space, we consider a pair of identical ↑ fermions of some species or in some internal state and a pair of identical ↓ fermions of another species or in another state. There is a resonant s -wave interaction (that is, of zero range and infinite scattering length) between fermions in different pairs and no interaction within the same pair. We study whether this 2 +2 fermionic system can exhibit (as the 3 +1 fermionic system) a four-body Efimov effect in the absence of three-body Efimov effect, that is, the mass ratio α between ↑ and ↓ fermions and its inverse are both smaller than 13.6069…. For this purpose, we investigate scale invariant zero-energy solutions of the four-body Schrödinger equation, that is, positively homogeneous functions of the coordinates of degree s -7 /2 , where s is a generalized Efimov exponent that becomes purely imaginary in the presence of a four-body Efimov effect. Using rotational invariance in momentum space, it is found that the allowed values of s are such that M (s ) has a zero eigenvalue; here the operator M (s ) , that depends on the total angular momentum ℓ , acts on functions of two real variables (the cosine of the angle between two wave vectors and the logarithm of the ratio of their moduli), and we write it explicitly in terms of an integral matrix kernel. We have performed a spectral analysis of M (s ) , analytical and for an arbitrary imaginary s for the continuous spectrum and numerical and limited to s =0 and ℓ ≤12 for the discrete spectrum. We conclude that no eigenvalue of M (0 ) crosses zero over the mass ratio interval α ∈[1 ;13.6069 ⋯] , even if, in the parity sector (-1) ℓ, the continuous spectrum of M (s ) has everywhere a zero lower border. As a consequence, there is no possibility of a four-body Efimov effect for the 2 +2 fermions. We also enunciated a conjecture for the fourth virial coefficient of the unitary spin-1 /2 Fermi gas, inspired from the known
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.
An exactly solvable quantum four-body problem associated with the symmetries of an octacube
NASA Astrophysics Data System (ADS)
Olshanii, Maxim; Jackson, Steven G.
2015-10-01
In this article, we show that eigenenergies and eigenstates of a system consisting of four one-dimensional hard-core particles with masses 6m, 2m, m, and 3m in a hard-wall box can be found exactly using Bethe Ansatz. The Ansatz is based on the exceptional affine reflection group {\\tilde{F}}4 associated with the symmetries and tiling properties of an octacube—a Platonic solid unique to four-dimensions, with no three-dimensional analogues. We also uncover the Liouville integrability structure of our problem: the four integrals of motion in involution are identified as invariant polynomials of the finite reflection group F4, taken as functions of the components of momenta.
Variational Proof of the Existence of the Super-Eight Orbit in the Four-Body Problem
NASA Astrophysics Data System (ADS)
Shibayama, Mitsuru
2014-10-01
Using the variational method, Chenciner and Montgomery (Ann Math 152:881-901, 2000) proved the existence of an eight-shaped periodic solution of the planar three-body problem with equal masses. Just after the discovery, Gerver numerically found a similar periodic solution called "super-eight" in the planar four-body problem with equal mass. In this paper we prove the existence of the super-eight orbit by using the variational method. The difficulty of the proof is to eliminate the possibility of collisions. In order to solve it, we apply the scaling technique established by Tanaka (Ann Inst H Poincaré Anal Non Linéaire 10:215-238, 1993), (Proc Am Math Soc 122:275-284, 1994) and investigate the asymptotic behavior of a binary collision.
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)
Masago, Bruna Yukiko Pinheiro Lopes; Prado, A. F. B. A.; Chiaradia, Ana Paula Marins; Gomes, Vivian Martins
2016-02-01
Space missions to visit small bodies of the Solar System are important steps to improve our knowledge of the Solar System. Usually those bodies do not have well known characteristics, as their gravity field, which make the mission planning a difficult task. The present paper has the goal of studying orbits around the triple asteroid 2001SN263, a Near-Earth Asteroid (NEA). A mission to this system allows the exploration of three bodies in the same trip. The distances reached by the spacecraft from those three bodies have fundamental importance in the quality of their observations. Therefore, the present research has two main goals: (i) to develop a semi-analytical mathematical model, which is simple, but able to represent the main characteristics of that system; (ii) to use this model to find orbits for a spacecraft with the goal of remaining the maximum possible time near the three bodies of the system, without the need of space maneuvers. This model is called "Precessing Inclined Bi-Elliptical Problem with Radiation Pressure" (PIBEPRP). The use of this model allow us to find important natural orbits for the exploration of one, two or even the three bodies of the system. These trajectories can be used individually or combined in two or more parts using orbital maneuvers.
Four-body model for transfer excitation
Harris, A. L.; Peacher, J. L.; Madison, D. H.; Colgan, J.
2009-12-15
We present here a four-body model for transfer-excitation collisions, which we call the four-body transfer-excitation (4BTE) model. Each two-body interaction is explicitly included in the 4BTE model, allowing us to study the effects of individual two-body interactions. We apply our model to fully differential cross sections for proton+helium collisions, and study the effect of the incident projectile-atom interaction, the scattered projectile-ion interaction, the projectile-nuclear interaction, and electron correlation within the target atom.
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.
Central configurations of four bodies with an axis of symmetry
NASA Astrophysics Data System (ADS)
Érdi, Bálint; Czirják, Zalán
2016-05-01
A complete solution is given for a symmetric case of the problem of the planar central configurations of four bodies, when two bodies are on an axis of symmetry, and the other two bodies have equal masses and are situated symmetrically with respect to the axis of symmetry. The positions of the bodies on the axis of symmetry are described by angle coordinates with respect to the outside bodies. The solution is such, that giving the angle coordinates, the masses for which the given configuration is a central configuration, can be computed from simple analytical expressions of the angles. The central configurations can be described as one-parameter families, and these are discussed in detail in one convex and two concave cases. The derived formulae represent exact analytical solutions of the four-body problem.
Three- and four-body structure of S = -2 hypernuclei
Hiyama, E.
2006-11-02
Energy levels of the double-{lambda} hypernuclei, {sub {lambda}}{sub {lambda}}{sup 7}He, {sub {lambda}}{sub {lambda}}{sup 7}Li, {sub {lambda}}{sub {lambda}}{sup 8}Li, {sub {lambda}}{sub {lambda}}{sup 9}Li, {sub {lambda}}{sub {lambda}}{sup 9}Be and {sub {lambda}}{sub {lambda}}{sup 10}Be are discussed. Interactions between the constituent particles are determined so as to reproduce reasonably the observed low-energy properties of the {alpha} + x nuclei, x + {lambda}, {alpha} + x + {lambda} and {alpha} + {lambda} + {lambda} systems. With no adjustable parameters for the {alpha} + x + {lambda} + {lambda} system, B{lambda}{lambda} of ground and bound excited states of the double-{lambda} hypernuclei with A = 7-10 are calculated using Gaussian Expansion Method. Furthermore, the four-body caluclation of {sub {lambda}}{sub {lambda}}{sup 4}H and NNN{xi} were peformed. The {lambda}{lambda} - {xi}N coupling was very important in making {sub {lambda}}{sub {lambda}}{sup 4}H bound.
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.
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. PMID:22852598
NASA Astrophysics Data System (ADS)
Rakshit, D.; Blume, D.
2012-06-01
It has been predicted that four-body systems with angular momentum L=1 and parity π=+1 exhibit four-body resonances [1,2] and Efimov physics [3]. To treat these phenomena in the hyperspherical framework, we extend the work of von Stecher and Greene [4] to finite angular momenta. In particular, we employ explicitly correlated Gaussian basis functions with global vectors to solve the hyperangular Schr"odinger equation for four-body systems with L^π=1^+ and 1^- symmetry. We apply the approach to four-fermion systems with unequal masses.[4pt] [1] K. M. Daily and D. Blume, Phys. Rev. Lett. 105, 170403 (2010).[0pt] [2] S. Gandolfi and J. Carlson, arXiv: 1006.5186v1.[0pt] [3] Y. Castin, C. Mora and L. Pricoupenko, Phys. Rev. Lett. 105, 223201 (2010).[0pt] [4] J. von Stecher and C. H. Greene, Phys. Rev. A. 80, 022504 (2009).
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.
Development of the four-body corrected fragment molecular orbital (FMO4) method
NASA Astrophysics Data System (ADS)
Nakano, Tatsuya; Mochizuki, Yuji; Yamashita, Katsumi; Watanabe, Chiduru; Fukuzawa, Kaori; Segawa, Katsunori; Okiyama, Yoshio; Tsukamoto, Takayuki; Tanaka, Shigenori
2012-01-01
The four-body corrected fragment molecular orbital (FMO4) method was implemented at the second-order Møller-Plesset perturbation (MP2) level. A series of accuracy tests relative to the previous two-body and three-body treatments were performed. As expected, FMO4 provided better accuracy in total energies in comparison with the reference values by regular MO calculations. A nonconventional fragmentation by separating main and side chains in amino acid residues was examined for Ala-pentamer and Chignolin, where the four-body corrections were shown to be substantial. A large complex of HIV-1 protease (total 198 residues) with lopinavir was calculated as well. Furthermore, this new FMO scheme was successfully applied to adamantane-shaped clusters with three-dimensional bonding framework.
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.
Non-perturbative Calculation of the Scalar Yukawa Theory in Four-Body Truncation
NASA Astrophysics Data System (ADS)
Li, Yang; Karmanov, V. A.; Maris, P.; Vary, J. P.
2015-09-01
The quenched scalar Yukawa theory is solved in the light-front Tamm-Dancoff approach including up to four constituents (one scalar nucleon, three scalar pions). The Fock sector dependent renormalization is implemented. By studying the Fock sector norms, we find that the lowest two Fock sectors dominate the state even in the large-coupling region. The one-body sector shows convergence with respect to the Fock sector truncation. However, the four-body norm exceeds the three-body norm at the coupling.
NASA Astrophysics Data System (ADS)
Sayanjali, M.; Pourtakdoust, Seid H.
2015-05-01
This paper investigates the problem of optimal transfer trajectory design towards the L2 centered Halo orbit of the Sun-Earth three body system, where the initial launch is to start from a low Earth parking orbit (LEO). The proposed optimal transfer trajectory consists of an active part with low-thrust propulsion and a passive coasting part with no thrust or fuel consumption. In this respect a pseudo-stable manifold (SM) is initially determined through backward time integration of the bicircular four body (BCFB) equations of motion, whose initial states are obtained via stable manifolds of the restricted three body problem (R3BP). The optimal transfer trajectories are extracted via a hybrid direct-indirect optimization formulation applied on both R3BP as well as the BCFB models for comparative purposes. The optimal transfer trajectories are designed and analyzed for different Halo injection points (HOI), different Moon's final anomaly (FMA) and also for different locations of the burn-out conditions.
NASA Astrophysics Data System (ADS)
Mančev, Ivan
2007-05-01
The four-body continuum-distorted-wave model is formulated and used to investigate single electron capture in fast collisions of hydrogenlike projectiles with one- and multi-electron targets. The presented method of an analytical calculation of scattering integrals yields the total cross sections in terms of four-dimensional numerical quadratures. As an illustration, total cross sections are computed for electron capture processes in He+-H , He+-He , and Li2+-He collisions at intermediate and high impact energies. The contribution from the interelectron interaction during the collision is evaluated. The prior and post total cross sections are found to be in good agreement with the available experimental data.
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.
Masso, Majid
2012-01-01
Delaunay tessellation of the atomic coordinates for a crystallographic protein structure yields an aggregate of non-overlapping and space-filling irregular tetrahedral simplices. The vertices of each simplex objectively identify a quadruplet of nearest neighbor atoms in the protein. Here we apply Delaunay tessellation to 1417 high-resolution structures of single chains that share low sequence identity, for the purpose of determining the relative frequencies of occurrence for all possible nearest neighbor atomic quadruplet types. Alternative distributions are explored by varying two fundamental parameters: atomic alphabet selection and cutoff length for admissible simplex edges. The distributions are then converted to four-body potential functions by implementing the inverted Boltzmann principle, which requires calculating the distribution of the reference state. Two alternative definitions for the reference state are presented, which introduces a third parameter, and we derive and compare an array of such potential functions. These knowledge-based statistical potentials based on higher-order interactions complement and generalize the more commonly encountered atom-pair potentials, for which a number of approaches are described in the literature. PMID:23367374
Four-body charge transfer processes in collisions of bare projectile ions with helium atoms
NASA Astrophysics Data System (ADS)
Jana, S.; Mandal, C. R.; Purkait, M.
2015-02-01
Single-electron capture by a bare ion from a helium atom at intermediate and high energies in the framework of four-body distorted wave (DW-4B) approximation in both prior and post form has been considered. In the entrance channel, the initial bound state wave function is distorted by the incoming projectile ion, and the corresponding distortion is related to the Coulomb continuum states of the active electron and the residual target ion in the field of the projectile ion respectively. Continuum states of the active electron and the projectile ion in the field of the residual target ion are also included in the exit channel. It may be mentioned that the effect of dynamic electron correlation is explicitly taken into account through the complete perturbation potential. The total single-electron capture cross sections are obtained by summing over all contributions up to n = 3 shells and sub-shells respectively. In addition, the differential cross sections for alpha particle-helium collision are calculated at impact energies of 60, 150, 300, 450, and 630 keV amu-1, respectively. The cross sections exhibit a monotonically decreasing angular dependence, with clear peak structures around 0.1 to 0.2 mrad being found at low impact energies. The current theoretical results, both in prior and post forms of the transition amplitude for symmetric and asymmetric collision, are compared with the available theoretical and experimental results. Current computed results have been found to be satisfactory in comparison with other theoretical and experimental findings.
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.
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.
Structure of A=7 iso-triplet {lambda} hypernuclei studied with the four-body cluster model
Hiyama, E.; Yamamoto, Y.; Motoba, T.; Kamimura, M.
2009-11-15
The structure of the T=1 isotriplet hypernuclei, {sub {lambda}}{sup 7}He, {sub {lambda}}{sup 7}Li, and {sub {lambda}}{sup 7}Be within the framework of an {alpha}+{lambda}+N+N four-body cluster model is studied. Interactions between the constituent subunits are determined so as to reproduce reasonably well the observed low-energy properties of the {alpha}N, {alpha}{lambda}, {alpha}NN, and {alpha}{lambda}N subsystems. Furthermore, the two-body {lambda}N interaction is adjusted so as to reproduce the 0{sup +}-1{sup +} splitting of {sub {lambda}}{sup 4}H. Also, a phenomenological {lambda}N charge symmetry breaking (CSB) interaction is introduced. The {lambda} binding energy of the ground state in {sub {lambda}}{sup 7}He is predicted to be 5.16(5.36) MeV with (without) the CSB interaction. The calculated energy splittings of the 3/2{sup +}-5/2{sup +} states in {sub {lambda}}{sup 7}He and {sub {lambda}}{sup 7}Li are around 0.1 MeV. We point out that there is a three-layer structure of the matter distribution, {alpha} particle, {lambda} skin, and proton or neutron halo, in the {sub {lambda}}{sup 7}He(J=5/2{sup +}), {sub {lambda}}{sup 7}Li(J=5/2{sup +}), and {sub {lambda}}{sup 7}Be(J=1/2{sup +}) states.
Four-body calculation of 12C(α, γ)16O radiative capture reaction at stellar energies
NASA Astrophysics Data System (ADS)
Sadeghi, H.; Firoozabadi, M. M.
2016-01-01
On the basis of the four-alphamodel, the 12C(α, γ)16Oradiative capture process is investigated by using the four-body Faddeev-Yakubovsky equations as well as the two- and three-body electromagnetic currents. The present calculation is an application of our current conservation realistic potentials method for the 12C(α, γ)16Oradiative capture process. This work clears the way formore refinedmodels of radiative capture based on two- and three-body realistic potentials and current conservation. The calculation is carried out by considering the 4He + 12C (1 + 3) and the 8Be + 8Be (2 + 2) subamplitudes, respectively. Radiative capture 12C(α, γ)16Oreaction is one of the most important reactions in nuclear astrophysics. For this reaction, the electric dipole transitions between states with the same isospin are forbidden in the first order. Because the state 1+ and 0+ ground state nuclei 16O have zero isospin, thus the electric dipole radiations are not at the first order between two levels and electric dipole radiation will be the second order and electric dipole radiation is the same order as the electric quadrupole radiation. Therefore, we must consider the effects of both radiations. In comparison with other theoretical methods and available experimental data, good agreement is achieved for the E 1 and E 2 contribution to the cross section and the astrophysical S factor for this process.
Torres, J. J.; Neri, M.; Martinez, A.; Garcia, A.; Flores-Mendieta, Ruben
2006-10-01
Analytical radiative corrections of order ({alpha}/{pi})(q/M{sub 1}) are calculated for the four-body region of the Dalitz plot of baryon semileptonic decays when the s{sub 1}{center_dot}p{sub 2} correlation is present. Once the final result is available, it is possible to exhibit it in terms of the corresponding final result of the three-body region following a set of simple changes in the latter. We cover two cases, a charged and a neutral polarized decaying baryon.
Neri, M.; Martinez, A.; Garcia, A.; Torres, J. J.; Flores-Mendieta, Ruben
2007-05-01
Analytical radiative corrections of order ({alpha}/{pi})(q/M{sub 1}) are calculated for the four-body region of the Dalitz plot of baryon semileptonic decays when the s-circumflex{sub 1}{center_dot}l-circumflex correlation is present. Once the final result is available, it is possible to exhibit it in terms of the corresponding final result of the three-body region following a set of simple changes in the latter, except for a few exceptions. We cover two cases, a charged and a neutral polarized decaying baryon.
Sánchez-González, Gilberto; Kim, Jae-Kwan; Kim, Deok-Soo; Garduño-Juárez, Ramón
2013-08-01
We present a new four-body knowledge-based potential for recognizing the native state of proteins from their misfolded states. This potential was extracted from a large set of protein structures determined by X-ray crystallography using BetaMol, a software based on the recent theory of the beta-complex (β-complex) and quasi-triangulation of the Voronoi diagram of spheres. This geometric construct reflects the size difference among atoms in their full Euclidean metric; property not accounted for in a typical 3D Delaunay triangulation. The ability of this potential to identify the native conformation over a large set of decoys was evaluated. Experiments show that this potential outperforms a potential constructed with a classical Delaunay triangulation in decoy discrimination tests. The addition of a statistical hydrogen bond potential to our four-body potential allows a significant improvement in the decoy discrimination, in such a way that we are able to predict successfully the native structure in 90% of cases. PMID:23568277
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
NASA Technical Reports Server (NTRS)
Cohen, Robert J
1951-01-01
The effects of fineness ratio (14.2 and 12.2) and boattailing on aerodynamic characteristics of four bodies of revolution at Mach numbers from 1.50 to 1.99 within a range of angles of attack from 0 degrees 10 degrees at an approximate Reynolds number of 35x10(superscript)6 based on body length were investigated. A comparison of experimental data with available theory is included. At zero angle of attack, fineness ratio has no appreciable effect on model characteristics while boattailing and boattail convergence significantly affect fore drag and base drag. At angle of attack the effects are singular. The theory presented by H. J. Allen is a significant improvement over linearized potential theory in predicting aerodynamic characteristics.
Liu, Jie; Herbert, John M
2016-02-01
We introduce a "pair-pair" approximation to the generalized many-body expansion (pp-GMBE) as an approximation to a traditional four-body expansion, the latter of which is accurate but quickly becomes numerically unstable and ultimately intractable as the number of "bodies" (fragments) increases. The pp-GMBE method achieves a good balance between accuracy and efficiency by defining significant fragment pairs and then fragment quartets. An efficient fragmentation scheme is introduced for proteins such that the largest subsystems contain about 60 atoms. Application of the pp-GMBE method to proteins with as many as 70 amino acids (1142 atoms) reveals that pp-GMBE energies are quite faithful to those obtained when the same level of density functional theory is applied to the entire macromolecule. When combined with embedding charges obtained from natural population analysis, the pp-GMBE approach affords absolute energies that differ by 1-3 kcal/mol from full supersystem results, but it yields conformational energy profiles that are practically indistinguishable from the supersystem calculation at the same level of theory. PMID:26730608
Non-Collision Singularities in the Planar Two-Center-Two-Body Problem
NASA Astrophysics Data System (ADS)
Xue, Jinxin; Dolgopyat, Dmitry
2016-06-01
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.
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.
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.
... gov/ Home Body Getting your period Problem periods Problem periods It’s common to have cramps or feel ... doctor Some common period problems Signs of period problems top One way to know if you may ...
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... 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 ...
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... 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 ...
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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…
... 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 ...
... 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 ...
... back or groin? Yes You may have a KIDNEY STONE or another serious problem. EMERGENCY See your doctor ... the bladder, called INTERSTITIAL CYSTITIS, or from a KIDNEY STONE stuck in the bladder, or a chemical in ...
... 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, ...
... 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 ...
... 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 ...
... the home Dry mouth during cancer treatment Enteral nutrition - child - managing problems Gastrostomy feeding tube - bolus Jejunostomy feeding tube Mouth and neck radiation - discharge Multiple sclerosis - discharge Stroke - discharge Update Date 5/15/2014 ...
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... which nothing can be seen) Vision loss and blindness are the most severe vision problems. Causes Vision ... that look faded. The most common cause of blindness in people over age 60. Eye infection, inflammation, ...
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)
Richardson, D. L.; Cary, N. D.
1975-01-01
Bounded motion about Lagrange collinear libration points is considered for a perturbed elliptic-restricted problem. A practical application is the motion of a satellite near a libration point collinear with the sun and the earth-moon barycenter. Such a system is treated here as an earth-sun-satellite elliptic restricted problem with lunar perturbations. The method of dual time scales is utilized to develop a uniformly valid three-dimensional analytical solution to the satellite's equations of motion. The analytical development applies somewhat generally to that class of four-body problems where the second primary mass is much greater than the first, and the third primary mass is much greater than the second.
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…
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)
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... correct pelvic support problems? • Glossary What are pelvic support problems? The pelvic organs include the vagina , cervix , uterus , bladder , urethra , small intestines, and rectum . The pelvic ...
Four-body long-range interactions between ultracold weakly-bound diatomic molecules
NASA Astrophysics Data System (ADS)
Lepers, M.; Quéméner, G.; Luc-Koenig, E.; Dulieu, O.
2016-01-01
Using the multipolar expansion of electrostatic and magnetostatic potential energies, we characterize the long-range interactions between two weakly-bound diatomic molecules, taking as an example the paramagnetic Er2 Feshbach molecules which were produced recently. Since inside each molecule individual atoms conserve their identity, the intermolecular potential energy can be expanded as the sum of pairwise atomic potential energies. In the case of Er2 Feshbach molecules, we show that the interaction between atomic magnetic dipoles gives rise to the usual {R}-3 term of the multipolar expansion, where R is the intermolecular distance, but also to additional terms scaling as {R}-5, {R}-7, and so on. Those terms are due to the interaction between effective molecular multipole moments, and are strongly anisotropic with respect to the orientation of the molecules. Similarly, the atomic pairwise van der Waals interaction results in {R}-6, {R}-8, ... terms in the intermolecular potential energy. By calculating the reduced electric-quadrupole moment of erbium ground level < {}3{H}6| | {\\hat{Q}}2| | {}3{H}6> =-1.305 a.u., we also demonstrate that the electric–quadrupole interaction energy is negligible with respect to the magnetic dipole and van der Waals interaction energies. The general formalism presented in this article can be applied to calculate the long-range potential energy between arbitrary charge distributions composed of almost free subsystems.
On CP asymmetries in two-, three- and four-body D decays
NASA Astrophysics Data System (ADS)
Bigi, Ikaros I.; Paul, Ayan
2012-03-01
Indirect and direct CP violations have been established in K L and B d decays. They have been found in two-body decay channels — with the exception of K L → π + π - e + e - transitions. Evidence for direct CP asymmetry has just appeared in LHCb data on A CP( D 0 → K + K -) - A CP( D 0 → π + π -) with 3.5 σ significance. Manifestations of New Dynamics (ND) can appear in CP asymmetries just below experimental bounds. We discuss D_{{(s)}}^{± } , {D^0}/{overline D^0} and D L / D S transitions to 2-, 3- and 4-body final states with a comment on predictions for inclusive vs. exclusive CP asymmetries. In particular we discuss T asymmetries in D → h 1 h 2 l + l - in analogy with K L → π + π - e + e - transitions due to interference between M1, internal bremsstrahlung and possible E1 amplitudes. Such an effect depends on the strength of CP violation originating from the ND — as discussed here for Little Higgs Models with T parity and non-minimal Higgs sectors — but also in the interferences between these amplitudes even in the Standard Model. More general lessons can be learnt for T asymmetries in non-leptonic D decays like D → h 1 h 2 h 3 h 4. Such manifestations of ND can be tested at LHCb and other Super-Flavour Factories like the projects at KEK near Tokyo and at Tor Vergata/Frascati near Rome.
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
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.
The Algorithm Selection Problem
NASA Technical Reports Server (NTRS)
Minton, Steve; Allen, John; Deiss, Ron (Technical Monitor)
1994-01-01
Work on NP-hard problems has shown that many instances of these theoretically computationally difficult problems are quite easy. The field has also shown that choosing the right algorithm for the problem can have a profound effect on the time needed to find a solution. However, to date there has been little work showing how to select the right algorithm for solving any particular problem. The paper refers to this as the algorithm selection problem. It describes some of the aspects that make this problem difficult, as well as proposes a technique for addressing it.
Pérez, Diana I
2005-01-01
In this paper I present, in the first place, two of the main problems in the philosophy of mind: 1) the problem of the criteria of the mental, and 2) the problem of the relationship between the mental and the physical. In the last part, I mention two problems highly discussed nowadays which, in my view, will produce the most important advance in the knowledge of our minds in the next decades: the problem of consciousness and its neural basis, and the problem of the origin and development of a theory of mind. PMID:16220149
Locating Problems with Quality Circles.
ERIC Educational Resources Information Center
White, Donald D.; Bednar, David A.
1985-01-01
Five categories of common quality circles problems are identified to help firms anticipate difficulties and avert circle failures. These categories include encountered internal problems, encountered external problems, created internal problems, created external problems, and interface problems. Solutions are suggested. (CT)
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...
ERIC Educational Resources Information Center
Choate, Joyce S.
1990-01-01
The initial step of a strategic process for solving mathematical problems, "studying the question," is discussed. A lesson plan for teaching students to identify and revise arithmetic problems is presented, involving directed instruction and supervised practice. (JDD)
Traveling with breathing problems
If you have breathing problems and you: Are short of breath most of the time Get short of breath when you walk 150 ... or less Have been in the hospital for breathing problems recently Use oxygen at home, even if ...
Problem: Heart Valve Regurgitation
... Pressure High Blood Pressure Tools & Resources Stroke More Problem: Heart Valve Regurgitation Updated:May 26,2016 What ... content was last reviewed May 2016. Heart Valve Problems and Disease • Home • About Heart Valves • Heart Valve ...
... Pressure High Blood Pressure Tools & Resources Stroke More Problem: Heart Valve Stenosis Updated:Aug 10,2016 About ... content was last reviewed May 2016. Heart Valve Problems and Disease • Home • About Heart Valves • Heart Valve ...
... gov/ency/patientinstructions/000663.htm Women and sexual problems To use the sharing features on this page, ... feel better about your sex life. Common Sexual Problems You may have sexual dysfunction if you are ...
... 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, ...
There are many problems that can keep a woman from enjoying sex. They include Lack of sexual desire Inability to become aroused Lack of orgasm, or sexual climax Painful intercourse These problems may have physical or psychological causes. Physical causes ...
... this can damage your eyes. The most common problem is diabetic retinopathy. It is a leading cause ... surgery, with follow-up care. Two other eye problems can happen to people with diabetes. A cataract ...
ERIC Educational Resources Information Center
Karrison, Joan; Carroll, Margaret Kelly
1991-01-01
Students with language and learning disabilities may have difficulty solving mathematics word problems. Use of a sequential checklist, identifying clues and keywords, and illustrating a problem can all help the student identify and implement the correct computational process. (DB)
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)
... 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 ...
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.
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…
NASA Astrophysics Data System (ADS)
Marx, G.
Drake's formula for the possible number of independent civilizations in the Galaxy is discussed in the light of several new hypotheses (e.g., Lovelock's Gaia hypothesis). Emphasis is placed on ways to overcome the time problem, i.e., the problem of how to communicate with civilizations that may arise in the future. Electronic, nucleonic, and bionic approaches to this problem are discussed.
ERIC Educational Resources Information Center
DEVANE, J.R.; RIMOLDI, H.J.A.
CHANGES WERE STUDIED IN THE PROBLEM-SOLVING BEHAVIOR OF HIGH SCHOOL STUDENTS AS A FUNCTION OF A CAREFULLY DESIGNED TRAINING PROGRAM. TRAINING WAS DEFINED AS THE DEVELOPMENT OF STUDENT AWARENESS OF PROBLEM-SOLVING STRATEGIES USED. INSTRUMENTS WERE DEVELOPED AND REFINED TO MEASURE PROBLEM-SOLVING BEHAVIOR. SPECIFICALLY TESTED WAS THE FOLLOWING…
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…
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…
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…
Florkowski, Antoni; Gruszczyński, Wojciech; Gałecki, Piotr; Szubert, Sławomir; Klus, Marek; Zboralski, Krzysztof
2008-01-01
An overusing and an addiction to alcoholic drinks are important problems in a medical society. The studies made in the United States had documented that about 8-12% doctors were addicted to alcohol. In many cases the doctors are able to keep their problem as a secret and their activity is satisfied up to the moment when a decrease is noticed. Some factors--such as a high level of stress--predispose doctors to alcoholic problems especially surgeons. Alcohol problems should be identified as early as possible, and therapy ought to be given as well. There is no reason to hide the problem. PMID:19025048
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.
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)
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.
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.
Finsterle, S.
1997-11-01
This report contains a collection of ITOUGH2 sample problems. It complements the ITOUGH2 User`s Guide [Finsterle, 1997a], and the ITOUGH2 Command Reference [Finsterle, 1997b]. ITOUGH2 is a program for parameter estimation, sensitivity analysis, and uncertainty propagation analysis. It is based on the TOUGH2 simulator for non-isothermal multiphase flow in fractured and porous media [Preuss, 1987, 1991a]. The report ITOUGH2 User`s Guide [Finsterle, 1997a] describes the inverse modeling framework and provides the theoretical background. The report ITOUGH2 Command Reference [Finsterle, 1997b] contains the syntax of all ITOUGH2 commands. This report describes a variety of sample problems solved by ITOUGH2. Table 1.1 contains a short description of the seven sample problems discussed in this report. The TOUGH2 equation-of-state (EOS) module that needs to be linked to ITOUGH2 is also indicated. Each sample problem focuses on a few selected issues shown in Table 1.2. ITOUGH2 input features and the usage of program options are described. Furthermore, interpretations of selected inverse modeling results are given. Problem 1 is a multipart tutorial, describing basic ITOUGH2 input files for the main ITOUGH2 application modes; no interpretation of results is given. Problem 2 focuses on non-uniqueness, residual analysis, and correlation structure. Problem 3 illustrates a variety of parameter and observation types, and describes parameter selection strategies. Problem 4 compares the performance of minimization algorithms and discusses model identification. Problem 5 explains how to set up a combined inversion of steady-state and transient data. Problem 6 provides a detailed residual and error analysis. Finally, Problem 7 illustrates how the estimation of model-related parameters may help compensate for errors in that model.
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…
Problem Solving Techniques Seminar.
ERIC Educational Resources Information Center
Massachusetts Career Development Inst., Springfield.
This booklet is one of six texts from a workplace literacy curriculum designed to assist learners in facing the increased demands of the workplace. Six problem-solving techniques are developed in the booklet to assist individuals and groups in making better decisions: problem identification, data gathering, data analysis, solution analysis,…
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
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)
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).
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…
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
Wilmington Public Schools, DE.
The general purpose of the twelfth grade course is to help the student assume his role as a decision-maker in a democratic society. The nature and complexity of contemporary problems are examined using this guide to enable the student: 1) to analyze alternative solutions to these problems; 2) to develop attitudes and values appropriate to a…
ERIC Educational Resources Information Center
Mann, Philip H.; Suiter, Patricia A.
This teacher training module classifies visual channel problems into the following four main areas: visual perception, revisualization (memory), visual-motor (eye-hand coordination), and ocular-motor tasks. Specific deficits are listed under these main headings, behaviors are given to help identify the problem, and ways to improve the condition…
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…
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
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…
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…
NASA Astrophysics Data System (ADS)
1981-01-01
The problems related to aircraft noise were studied. Physical origin (sound), human reaction (noise), quantization of noise and sound sources of aircraft noise are discussed. Noise abatement at the source, technical, fleet-political and air traffic measures are explained. The measurements and future developments are also discussed. The position of Lufthansa as regards aircraft noise problems is depicted.
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…
NASA Technical Reports Server (NTRS)
Lippisch, Espenlaub
1922-01-01
Any one endeavoring to solve the problem of soaring flight is confronted not only by structural difficulties, but also by the often far more difficult aerodynamic problem of flight properties and efficiency, which can only be determined by experimenting with the finished glider.
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.
... problems that can lead to dislocation of the hip bones. This is also called dysplasia (say: "diss-play-see-uh"). This means that ... problems later in life? Source Screening for Developmental Dysplasia of the Hip by LM French, M.D., and FR Dietz, ...
ERIC Educational Resources Information Center
Ross, Robert
This paper focusses on problems involved in adopting the newer modes of social science and professionalism. The complexities which precede these problems are recognized. It is mentioned that many recent entrants to these fields have made value commitments in their professionalism without very long detention at the portals of objectivity or…
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…
Problem Solving and Intelligence.
ERIC Educational Resources Information Center
Resnick, Lauren B.; Glaser, Robert
This paper argues that a major aspect of intelligence is the ability to solve problems and that careful analysis of problem-solving behavior is a means of specifying many of the psychological processes that make up intelligence. The focus is on the mechanisms involved when, in the absence of complete instruction, a person must "invent" a new…
ERIC Educational Resources Information Center
Karns, Phyllis Spear
The relationship of educational preparation to the problem- solving performance of 55 hospital employed baccalaureate and associate degree nurses working in Wyoming hospitals was studied. Participant data were collected that might correlate with problem-solving ability: age, years of experience in nursing, years of work experience in a…
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;…
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…
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.…
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.
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. PMID:12005916
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.
... 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
Pool, Ithiel de Sola
1979-01-01
Presents several anticipated problems to be handled at the 1979 World Administrative Conference including an orbital allocation plan, political and ideological issues concerning sovereignty and prior consent, spectrum assignments, and sharing of TV frequencies with land mobile radio. (JMF)
ERIC Educational Resources Information Center
Cunningham, Luvern L.
1969-01-01
Evaluation of school administrators to determine whether they are truly performing their functions adequately has presented a problem of long standing since most administrators find excuses to avoid appraisal of their performance. (CK)
... problems may include: Getting older: a woman's sex drive often decreases with age. This is normal. It ... pressure, depression, and chemotherapy can decrease your sex drive or make it hard to have an orgasm. ...
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 ... Breastfeeding (nursing) your baby can be a good experience for both the mother and the baby. It ...
... life expectancy. Do children with Down syndrome have eye problems? Individuals with Down syndrome are at increased ... When should children with Down syndrome receive an eye exam? The American Academy of Pediatrics recommends that ...
... days, such as in painting and carpentry Poor posture over many years Aging Rotator cuff tears TEARS ... also help prevent rotator cuff problems. Practice good posture to keep your rotator cuff tendons and muscles ...
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)
... 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. ...
... 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).
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. PMID:15932043
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)
Solving Tommy's Writing Problems.
ERIC Educational Resources Information Center
Burdman, Debra
1986-01-01
The article describes an approach by which word processing helps to solve some of the writing problems of learning disabled students. Aspects considered include prewriting, drafting, revising, and completing the story. (CL)
... 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 ...
Nicholson, Keith; Martelli, Michael F
2004-01-01
Pain problems, especially posttraumatic headache, are very common following head trauma. Pain may be the most significant problem, more disabling than any brain or other injuries, and interfering with aspects of cognition or other function. However, posttraumatic headache and most other chronic posttraumatic pain problems remain poorly understood. This article reviews fundamental issues that should be considered in understanding the nature of chronic pain including the distinction between acute and chronic pain; neurobiological distinctions between the lateral and medial pain system; nociceptive versus neuropathic or other central pain; sensitization effects; the widely accepted view of chronic pain as a multidimensional subjective experience involving sensory, motivational-affective and cognitive-behavioral components; the problem of mind-body dualism; the role of psychosocial factors in the onset, maintenance, exacerbation or severity of pain; plus issues of response bias and malingering. PMID:14732827
... 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, ...
... 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
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 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.
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.
Overcoming breastfeeding problems
... position Reducing distractions during nursing, performing a gentle massage, and applying heat to the breast Nursing often ( ... JL, et al, eds. Obstetrics: Normal and Problem Pregnancies . 6th ed. Philadelphia, PA: Elsevier Saunders; 2012:chap ...
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.
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.
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. PMID:12315680
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.
Living with Bowel Control Problems
... Home Living with Bowel Control Problems Resources Bowel Control Awareness Campaign Home Resources for Health Care Providers ... Living with Bowel Control Problems Living with Bowel Control Problems Living with a bowel control problem can ...
Dzamonja, Mirna
2006-12-15
This is a paper in mathematics, specifically in set theory. On the example of the measure recognition problem (MRP), the paper highlights the phenomenon of the utility of a multidisciplinary mathematical approach to a single mathematical problem, in particular, the value of a set-theoretic analysis. MRP asks if for a given Boolean algebra, B, and a property, Phi, of measures, one can recognize by purely combinatorial means if B supports a strictly positive measure with property Phi. The most famous instance of this problem is MRP (countable additivity), and in the first part of the paper, we survey the known results on this and some other problems. We show how these results naturally lead to asking about two other specific instances of the problem MRP, namely MRP (non-atomic) and MRP (separable). Then, we show how our recent work gives an easy solution to the former of these problems and some partial information about the latter. The long-term goal of this line of research is to obtain a structure theory of Boolean algebras that support a finitely additive strictly positive measure, along the lines of Maharam theorem, which gives such a structure theorem for measure algebras. PMID:17090453
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.
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.
Colored Traveling Salesman Problem.
Li, Jun; Zhou, MengChu; Sun, Qirui; Dai, Xianzhong; Yu, Xiaolong
2015-11-01
The multiple traveling salesman problem (MTSP) is an important combinatorial optimization problem. It has been widely and successfully applied to the practical cases in which multiple traveling individuals (salesmen) share the common workspace (city set). However, it cannot represent some application problems where multiple traveling individuals not only have their own exclusive tasks but also share a group of tasks with each other. This work proposes a new MTSP called colored traveling salesman problem (CTSP) for handling such cases. Two types of city groups are defined, i.e., each group of exclusive cities of a single color for a salesman to visit and a group of shared cities of multiple colors allowing all salesmen to visit. Evidences show that CTSP is NP-hard and a multidepot MTSP and multiple single traveling salesman problems are its special cases. We present a genetic algorithm (GA) with dual-chromosome coding for CTSP and analyze the corresponding solution space. Then, GA is improved by incorporating greedy, hill-climbing (HC), and simulated annealing (SA) operations to achieve better performance. By experiments, the limitation of the exact solution method is revealed and the performance of the presented GAs is compared. The results suggest that SAGA can achieve the best quality of solutions and HCGA should be the choice making good tradeoff between the solution quality and computing time. PMID:25494521
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 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.
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.
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.
NASA Astrophysics Data System (ADS)
Kranakis, Evangelos; Krizanc, Danny
A man walks into a men's room and observes n empty urinals. Which urinal should he pick so as to maximize his chances of maintaining privacy, i.e., minimize the chance that someone will occupy a urinal beside him? In this paper, we attempt to answer this question under a variety of models for standard men's room behavior. Our results suggest that for the most part one should probably choose the urinal furthest from the door (with some interesting exceptions). We also suggest a number of variations on the problem that lead to many open problems.
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.
NASA Astrophysics Data System (ADS)
Voitkevich, Georgii V.
The main problems of space chemistry are examined, including the origin and abundance of chemical elements, their migration to different regions of the universe, the formation of the chemical composition of cosmic bodies, and the chemical evolution of the solar system and the origin of life. Based on current astrophysical and space-chemical data, the main stages of the evolution of matter from the beginning of universe expansion to the formation of the solar system are described. The problem of the origin of life is examined in the light of space-chemical data on the formation of high-molecular compounds before the formation of the planets.
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)…
Every pregnancy has some risk of problems. The causes can be conditions you already have or conditions you develop. They also include being pregnant with ... health care provider about how to minimize your risk before you get pregnant. Once you are pregnant, ...
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)…
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…
... age 6 months. That's because children start learning speech and language long before they talk. Hearing problems can be temporary or permanent. Sometimes, ear infections, injuries or diseases affect hearing. If your child does not hear well, get help. NIH: National ...
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…
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…
Correct Problems, Desperate Solutions.
ERIC Educational Resources Information Center
Donohue, William A.
1996-01-01
Argues that the social problems confronting America have been bombarded with ill-conceived and unsuccessful social policy largely driven by fear. Explains that parental licensing is a draconian and unworkable solution. Vouchers for indigent youth to attend Catholic schools, developing after-school and summer programs, and reforming welfare are…
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…
Dermatologic problems of musicians.
Rimmer, S; Spielvogel, R L
1990-04-01
The unique occupational dermatologic disorders of musicians are reviewed and compiled to provide the clinician with a reference list. Our results were obtained by a survey of 24 members of a professional symphony orchestra. The results of the survey revealed a significant incidence of occupationally related skin problems in musicians. PMID:2138638
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.
"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…
Transformation Problem Solving Abilities.
ERIC Educational Resources Information Center
Harmel, Sarah Jane
The relationship between transformation problem performance and Guilford Structure of Intellect (SI) abilities is explored. During two group sessions 42 females and 35 males, age 18-39, were administered 12 Guilford SI tests exemplifying all five symbolic content (numeric) operations, and three contents in the divergent production area. Logical…
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…
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
Olson, Alton T.
1993-01-01
Presents a series of solution methods to the Eight Queens Problem of placing eight queens on a chess board so that no one queen can capture another. Solution methods progress from empirical approaches to the use of computer algorithms. Geometric transformations are used to find other solutions. (MDH)
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…
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
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…
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…
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…
Problem Solving Using Calculators.
ERIC Educational Resources Information Center
Billings, Karen; Moursund, David
1978-01-01
The first part in the serialized version of a book on the use of calculators for problem solving is presented. It contains prefaces for teachers and students and a chapter on getting started which includes topics such as symmetries, operations, powers, and chaining. (MP)
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.
Learning through Problem Solving.
ERIC Educational Resources Information Center
Murray, Hanlie; Olivier, Alwyn; Human, Piet
After conducting several studies on young students' understanding of particular concepts before, during, and after instruction, this paper focuses on the two small scale and several informal teaching experiments based on the idea that the teacher should pose problems to students for which they do not yet have a routine solution method available,…
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…
ERIC Educational Resources Information Center
Vagianos, Louis
1972-01-01
The library problem consists of equal parts of external and internal noise. The external noise consists of the volume of publication. The internal noise can be characterized by the present and continuing brouhaha concerning reform of library education. Scientists frankly regard librarians as impediments to information. (Author/NH)
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…
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
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
Onions, Chris
1991-01-01
Presented are the solutions generated by a fifth grade class to the problem of finding the sum of the number of blocks in a pyramid with a bottom layer containing seven blocks. Three methods were recorded: a levels method, a columns method, and a vertical slice method. (MDH)
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…
Symmetries of Spectral Problems
NASA Astrophysics Data System (ADS)
Shabat, A.
Deriving abelian KdV and NLS hierarchies, we describe non-abelian symmetries and "pre-Lax" elementary approach to Lax pairs. Discrete symmetries of spectral problems are considered in Sect. 4.2. Here we prove Darboux classical theorem and discuss a modern theory of dressing chains.
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…
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)
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)
Thermodynamics with Design Problems.
ERIC Educational Resources Information Center
Cilento, E. V.; Sears, J. T.
1983-01-01
Discusses how basic thermodynamics concepts are integrated with design problems. Includes course goals, instructional strategies, and major advantages/disadvantages of the integrated design approach. Advantages include making subject more concrete, emphasizing interrelation of variables, and reinforcing concepts by use in design analysis; whereas…
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)
Cognitive Problems (Disorientation, Perception, Attention, Learning and Problem-Solving)
... SOMEONE WITH EMOTIONAL & BEHAVIORAL NEEDS Cognitive Problems (Disorientation, Perception, Attention, Learning & Problem-Solving) Cognition is the process ... What Are Some Other Cognitive Problems? What Is Perception? Remember What Is Attention or Concentration? More Resources ...
Bicriteria network design problems
Marathe, M.V.; Ravi, R.; Sundaram, R.; Ravi, S.S.; Rosenkrantz, D.J.; Hunt, H.B. III
1994-12-31
We study several bicriteria network design problems phrased as follows: given an undirected 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. Define an ({alpha}, {beta})-approximation algorithm as a polynomial-time algorithm that produces a solution in which the first objective value is at most {alpha} times the budget, and the second objective value is at most {alpha} times the minimum cost of a network obeying the budget oil the first objective. We, present the first approximation algorithms for bicriteria problems obtained by combining classical minimization objectives such as the total edge cost of the network, the diameter of the network and a weighted generalization of the maximum degree of any node in the network. We first develop some formalism related to bicriteria problems that leads to a clean way to state bicriteria approximation results. Secondly, when the two objectives are similar but only differ based on the cost function under which they are computed we present a general parametric search technique that yields approximation algorithms by reducing the problem to one of minimizing a single objective of the same type. Thirdly, we present an O(log n, log n)-approximation algorithm for finding a diameter-constrained minimum cost spanning tree of an undirected graph on n nodes generalizing the notion of shallow, light trees and light approximate shortest-path trees that have been studied before. 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.
Physics Problem Workbook, Student Manual.
ERIC Educational Resources Information Center
Jones, John L.
This workbook contains 50 undergraduate physics problems designed for use in conjunction with a computer in a time-sharing mode. Each of the problems includes a statement of the problem topic, a background description of the problem, problem objectives, suggested readings, and a related graph or figure. Various topics in general physics are…
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.
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.
The inhibiting bisection problem.
Pinar, Ali
2010-11-01
Given a graph where each vertex is assigned a generation or consumption volume, we try to bisect the graph so that each part has a significant generation/consumption mismatch, and the cutsize of the bisection is small. Our motivation comes from the vulnerability analysis of distribution systems such as the electric power system. We show that the constrained version of the problem, where we place either the cutsize or the mismatch significance as a constraint and optimize the other, is NP-complete, and provide an integer programming formulation. We also propose an alternative relaxed formulation, which can trade-off between the two objectives and show that the alternative formulation of the problem can be solved in polynomial time by a maximum flow solver. Our experiments with benchmark electric power systems validate the effectiveness of our methods.
NASA Astrophysics Data System (ADS)
Cheung, Clifford; Elor, Gilly; Hall, Lawrence J.
2012-01-01
We revisit the cosmology of the supersymmetric QCD axion, highlighting the existence of a serious cosmological axino problem that is fully analogous to the gravitino problem of overclosure via thermal production. A general analysis implies that the QCD axino has a mass greater than or equal to that of the gravitino in the absence of unnatural fine-tuning or sequestering. As a consequence, bounds from thermal gravitino and QCD axino production are complementary in parameter space, and together provide a quite stringent limit on the reheating temperature after inflation given by TR<103-106GeV for an axion decay constant of fa=109-1012GeV. Motivated by this result, we explore the cosmology of gravitino lightest supersymmetric particle and axino next to lightest supersymmetric particle at low TR and present three realistic scenarios for dark matter.
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.
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.
Hematological Problems of Pregnancy
Ballem, P.J.
1988-01-01
Hematologic complications are relatively common in pregnancy. Furthermore, many chronic hematologic disorders require special surveillance and intervention in pregnancy. In this brief review, the author discusses common nutritional anemias in pregnancy. She reviews the disorders of hemoglobin synthesis and the need for early genetic counselling and prenatal diagnosis, as well as the special requirements and problems affected patients encounter in pregnancy. An overview of the frequent causes of thrombocytopenia in pregnancy is given and an approach suggested to the management of both the mother and the fetus. An approach is also presented to the management of women at risk for thrombosis in pregnancy, a particularly vexing and controversial problem. The risks of the various forms of anticoagulation are reviewed. Finally, a brief review of obstetrical hemorrhage is presented along with some guidelines useful in its management. PMID:21253125
MCNP: Photon benchmark problems
Whalen, D.J.; Hollowell, D.E.; Hendricks, J.S.
1991-09-01
The recent widespread, markedly increased use of radiation transport codes has produced greater user and institutional demand for assurance that such codes give correct results. Responding to these pressing requirements for code validation, the general purpose Monte Carlo transport code MCNP has been tested on six different photon problem families. MCNP was used to simulate these six sets numerically. Results for each were compared to the set's analytical or experimental data. MCNP successfully predicted the analytical or experimental results of all six families within the statistical uncertainty inherent in the Monte Carlo method. From this we conclude that MCNP can accurately model a broad spectrum of photon transport problems. 8 refs., 30 figs., 5 tabs.
Solving bearing overheating problems
Jendzurski, T.
1995-05-08
Overheating is a major indicator, along with vibration and noise, of an underlying problem affecting a bearing or related components. Because normal operating temperatures vary widely from one application to another, no single temperature is a reliable sign of overheating in every situation. By observing an application when it is running smoothly, a technician can establish a benchmark temperature for a particular bearing arrangement. Wide deviations from this accepted norm generally indicate troublesome overheating. The list of possible causes of over-heating ranges from out-of-round housings and oversize shaft diameters to excessive lubrication and bearing preloading. These causes fall into two major categories: improper or faulty lubrication and mechanical problems, such as incorrect fits and tolerances. These are discussed along with solutions.
Momotani, Hiroko; Yamamoto, Haruyoshi
2014-02-01
This paper describes current issues in occupational mental health, occupational mental health activities currently underway, and priorities to improve the situation in Japan. A new tool to support these activities is then discussed. The incidence of employee mental health problems is rising, despite efforts to promote occupational mental health activities. The adoption of such activities is lagging behind in medium and small-sized enterprises. Priorities to improve occupational mental health include motivating business operators to address mental health issues, focusing more on prevention, and promoting mental health initiatives in medium and small-sized enterprises. Mental-Rosai, a web-based mental health check system, is a useful tool for the prevention of mental health problems and can provide support for medium and small-sized enterprises. PMID:24605529
The Boolean Isomorphism problem
Agrawal, M.; Thierauf, T.
1996-12-31
We investigate the computational complexity of the Boolean Isomorphism problem (BI): on input of two Boolean formulas F and G decide whether there exists a permutation of the variables of G such that F and G become equivalent. Our main result is a one-round interactive proof for BI, where the verifier has access to an NP oracle. To obtain this, we use a recent result from learning theory by Bshouty et.al. that Boolean formulas can be learned probabilistically with equivalence queries and access to an NP oracle. As a consequence, BI cannot be {sigma}{sup p}{sub 2} complete unless the Polynomial Hierarchy collapses. This solves an open problem posed in [BRS95]. Further properties of BI are shown: BI has And- and Or-functions, the counting version, No. BI, can be computed in polynomial time relative to BI, and BI is self-reducible.
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)
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.
Novak, L L
1996-01-01
Educating parents about normal, age-appropriate behavior in their children, teaching them basic behavioral techniques (such as the time-out and positive-reward systems) and giving them specific suggestions for intervention can increase parental confidence and decrease anxiety. Anticipating problems before they develop can help parents prevent inappropriate behavior patterns from developing in their children and may decrease abusive behavior. PMID:8546052
NASA Astrophysics Data System (ADS)
Santos, Emilio
1992-10-01
The problem of hidden variables in quantum mechanics is formalized as follows. A general or contextual (noncontextual) hidden-variables theory is defined as a mapping f: Q×M → C (f: Q→C) where Q is the set of projection operators in the appropriate (quantum) Hilbert space, M is the set of maximal Boolean subalgebras of Q and C is a (classical) Boolean algebra. It is shown that contextual (noncontextual) hidden-variables always exist (do not exist).
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. PMID:16138712
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.
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
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
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.
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
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.
Itin, P; Rufli, T
1986-08-30
Reports on skin problems in joggers are rare in medical literature. Jogger dermatoses are caused by repeated trauma, mechanic overuse, thermic effects, allergic-toxic reactions and infectious processes. Most common are bullosis mechanica, piezogenic papules, hyperkeratosis haemorrhagica and subungual haematomas. Contact allergies and infections such as athlete's foot, pitted keratolysis and pyoderma are well-known complications in joggers. Frostbite and actinic damage, abrasions of the nipples, collisions with vehicles and injuries by buzzards are further possible incidents to be reckoned with occasionally. In most cases, prophylaxis is possible by training adaptation and use of adequate footwear. Jogger dermatoses usually clear after a suitable jogging-free interval. PMID:3764389
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.