Simple analytic approximations for the Blasius problem
NASA Astrophysics Data System (ADS)
Iacono, R.; Boyd, John P.
2015-08-01
The classical boundary layer problem formulated by Heinrich Blasius more than a century ago is revisited, with the purpose of deriving simple and accurate analytical approximations to its solution. This is achieved through the combined use of a generalized Padé approach and of an integral iteration scheme devised by Hermann Weyl. The iteration scheme is also used to derive very accurate bounds for the value of the second derivative of the Blasius function at the origin, which plays a crucial role in this problem.
Analytical and sensory quality characteristics of twelve blueberry cultivars
Technology Transfer Automated Retrieval System (TEKTRAN)
The analytical and sensory quality characteristics of twelve blueberry cultivars were evaluated to determine what fruit quality characteristics consumers consider important and to evaluate if sensory quality characteristics were correlated to any analytical quality characteristics. Cultivars evaluat...
Analytical solutions to matrix diffusion problems
Kekäläinen, Pekka
2014-10-06
We report an analytical method to solve in a few cases of practical interest the equations which have traditionally been proposed for the matrix diffusion problem. In matrix diffusion, elements dissolved in ground water can penetrate the porous rock surronuding the advective flow paths. In the context of radioactive waste repositories this phenomenon provides a mechanism by which the area of rock surface in contact with advecting elements is greatly enhanced, and can thus be an important delay mechanism. The cases solved are relevant for laboratory as well for in situ experiments. Solutions are given as integral representations well suited for easy numerical solution.
Analytic prediction of airplane equilibrium spin characteristics
NASA Technical Reports Server (NTRS)
Adams, W. M., Jr.
1972-01-01
The nonlinear equations of motion are solved algebraically for conditions for which an airplane is in an equilibrium spin. Constrained minimization techniques are employed in obtaining the solution. Linear characteristics of the airplane about the equilibrium points are also presented and their significance in identifying the stability characteristics of the equilibrium points is discussed. Computer time requirements are small making the method appear potentially applicable in airplane design. Results are obtained for several configurations and are compared with other analytic-numerical methods employed in spin prediction. Correlation with experimental results is discussed for one configuration for which a rather extensive data base was available. A need is indicated for higher Reynolds number data taken under conditions which more accurately simulate a spin.
Assessing Cognitive Learning of Analytical Problem Solving
NASA Astrophysics Data System (ADS)
Billionniere, Elodie V.
Introductory programming courses, also known as CS1, have a specific set of expected outcomes related to the learning of the most basic and essential computational concepts in computer science (CS). However, two of the most often heard complaints in such courses are that (1) they are divorced from the reality of application and (2) they make the learning of the basic concepts tedious. The concepts introduced in CS1 courses are highly abstract and not easily comprehensible. In general, the difficulty is intrinsic to the field of computing, often described as "too mathematical or too abstract." This dissertation presents a small-scale mixed method study conducted during the fall 2009 semester of CS1 courses at Arizona State University. This study explored and assessed students' comprehension of three core computational concepts---abstraction, arrays of objects, and inheritance---in both algorithm design and problem solving. Through this investigation students' profiles were categorized based on their scores and based on their mistakes categorized into instances of five computational thinking concepts: abstraction, algorithm, scalability, linguistics, and reasoning. It was shown that even though the notion of computational thinking is not explicit in the curriculum, participants possessed and/or developed this skill through the learning and application of the CS1 core concepts. Furthermore, problem-solving experiences had a direct impact on participants' knowledge skills, explanation skills, and confidence. Implications for teaching CS1 and for future research are also considered.
Small divisor problem for an analytic q-difference equation
NASA Astrophysics Data System (ADS)
Xu, Bing; Zhang, Weinian
2008-06-01
Similar to the problem of linearization, the "small divisor problem" also arises in the discussion of invertible analytic solutions of a class of q-difference equations. In this paper we give the existence of such solutions under the Brjuno condition and prove that the equation may not have a nontrivial analytic solution when the Brjuno condition is violated. These results are applied to discussing a nonlinear iterative equation.
Microwave magnetoelectric fields: An analytical study of topological characteristics
NASA Astrophysics Data System (ADS)
Joffe, R.; Shavit, R.; Kamenetskii, E. O.
2015-10-01
The near fields originated from a small quasi-two-dimensional ferrite disk with magnetic-dipolar-mode (MDM) oscillations are the fields with broken dual (electric-magnetic) symmetry. Numerical studies show that such fields - called the magnetoelectric (ME) fields - are distinguished by the power-flow vortices and helicity parameters (E.O. Kamenetskii, R. Joffe, R. Shavit, Phys. Rev. E 87 (2013) 023201). These numerical studies can well explain recent experimental results with MDM ferrite disks. In the present paper, we obtain analytically topological characteristics of the ME-field modes. For this purpose, we used a method of successive approximations. In the second approximation we take into account the influence of the edge regions of an open ferrite disk, which are excluded in the first-approximation solving of the magnetostatic (MS) spectral problem. Based on the analytical method, we obtain a "pure" structure of the electric and magnetic fields outside the MDM ferrite disk. The analytical studies can display some fundamental features that are non-observable in the numerical results. While in numerical investigations, one cannot separate the ME fields from the external electromagnetic (EM) radiation, the present theoretical analysis allows clearly distinguish the eigen topological structure of the ME fields. Importantly, this ME-field structure gives evidence for certain phenomena that can be related to the Tellegen and bianisotropic coupling effects. We discuss the question whether the MDM ferrite disk can exhibit properties of the cross magnetoelectric polarizabilities.
Problem Solving, Reasoning, and Analytical Thinking in a Classroom Environment
ERIC Educational Resources Information Center
Robbins, Joanne K.
2011-01-01
Problem solving, reasoning, and analytical thinking are defined and described as teachable repertoires. This paper describes work performed at a school serving special needs children, Morningside Academy, that has resulted in specific procedures developed over the past 15 years. These procedures include modifying "Think Aloud Pair Problem Solving"…
Analytic semigroups: Applications to inverse problems for flexible structures
NASA Technical Reports Server (NTRS)
Banks, H. T.; Rebnord, D. A.
1990-01-01
Convergence and stability results for least squares inverse problems involving systems described by analytic semigroups are presented. The practical importance of these results is demonstrated by application to several examples from problems of estimation of material parameters in flexible structures using accelerometer data.
Analytic formulas for magnetron characteristic curves
Riyopoulos, S.
1995-12-31
A closed non-linear set of equations is obtained based on the guiding center fluid model to describe steady-state magnetron operation. Spoke charge effects are included self-consistently, by introducing a mean-field approximation so that the effective AC potential preserves the geometric similarity with the vacuum solutions. New characteristic equations, relating the anode current 1 and the RF power P to the applied DC voltage V at given RF frequency, are obtained. Previously obtained V-I equations disagree with experiments in that (a) anode current and RF power go to zero when the resonance condition V = V{sub s} is met, (b) the operation voltage V is a double-valued function of the current I; there exist two nearly symmetric operation points around V{sub s} at the same current I. Yet magnetrons, and the related crossed-field amplifiers, are known to exhibit stable operation with single valued V-I characteristics well below V{sub s}. Although zero gain at synchronism applies to other microwave devices (TWT`s, FEL`s), experimental results and particle simulations of crossed field devices suggest otherwise. The new formulas show reasonable agreement with experiments.
The limited relevance of analytical ethics to the problems of bioethics.
Holmes, R L
1990-04-01
Philosophical ethics comprises metaethics, normative ethics and applied ethics. These have characteristically received analytic treatment by twentieth-century Anglo-American philosophy. But there has been disagreement over their interrelationship to one another and the relationship of analytical ethics to substantive morality--the making of moral judgments. I contend that the expertise philosophers have in either theoretical or applied ethics does not equip them to make sounder moral judgments on the problems of bioethics than nonphilosophers. One cannot "apply" theories like Kantianism or consequentialism to get solutions to practical moral problems unless one knows which theory is correct, and that is a metaethical question over which there is no consensus. On the other hand, to presume to be able to reach solutions through neutral analysis of problems is unavoidably to beg controversial theoretical issues in the process. Thus, while analytical ethics can play an important clarificatory role in bioethics, it can neither provide, nor substitute for, moral wisdom. PMID:2351891
An analytically solvable eigenvalue problem for the linear elasticity equations.
Day, David Minot; Romero, Louis Anthony
2004-07-01
Analytic solutions are useful for code verification. Structural vibration codes approximate solutions to the eigenvalue problem for the linear elasticity equations (Navier's equations). Unfortunately the verification method of 'manufactured solutions' does not apply to vibration problems. Verification books (for example [2]) tabulate a few of the lowest modes, but are not useful for computations of large numbers of modes. A closed form solution is presented here for all the eigenvalues and eigenfunctions for a cuboid solid with isotropic material properties. The boundary conditions correspond physically to a greased wall.
Problems encountered during impact calculations using analytic equations of state
Kerrisk, J.F.; Harvey, W.B.
1997-02-01
During modeling of the impact of a projectile on a target or other calculations that bring materials together at high velocities, computer simulations of materials being shocked to high pressure and then releasing to low pressure are performed. Depending on the circumstances, the release to low pressure is often accompanied by release to a very low density. Numerical problems leading to very large sound speeds (and thus small time steps) or to negative Lagrangian volumes have been encountered during MESA-2D calculations of this nature. These problems can be traced to the behavior of the equation of state (EOS) in the limit as the density becomes much less than the normal or reference density. Although analytic solutions for expansion isentropes may show acceptable behavior in the low-density limit, numerical solutions can show undesirable behavior. Examples of this undesirable behavior in the low-density regime are given for some simple, analytic equations of state that have closed-form solutions for isentropes. The behavior of three analytic EOSs that are frequently used in MESA-2D calculations are then discussed. These EOSs are the Los Alamos EOS, the MESA polynomial EOS, and a Mie-Gruneisen EOS based on a linear relation between shock and particle velocity. The problems in the low-density region can be corrected for the Los Alamos EOS and the MESA polynomial EOS by the proper choice of EOS coefficients in the expansion region (density less than the reference density). Problems with the Mie-Gruneisen EOS can be corrected if the functional relationship between the Gruneisen parameter ({Tau}) and density differs above and below the reference density.
Does incubation enhance problem solving? A meta-analytic review.
Sio, Ut Na; Ormerod, Thomas C
2009-01-01
A meta-analytic review of empirical studies that have investigated incubation effects on problem solving is reported. Although some researchers have reported increased solution rates after an incubation period (i.e., a period of time in which a problem is set aside prior to further attempts to solve), others have failed to find effects. The analysis examined the contributions of moderators such as problem type, presence of solution-relevant or misleading cues, and lengths of preparation and incubation periods to incubation effect sizes. The authors identified a positive incubation effect, with divergent thinking tasks benefiting more than linguistic and visual insight tasks from incubation. Longer preparation periods gave a greater incubation effect, whereas filling an incubation period with high cognitive demand tasks gave a smaller incubation effect. Surprisingly, low cognitive demand tasks yielded a stronger incubation effect than did rest during an incubation period when solving linguistic insight problems. The existence of multiple types of incubation effect provides evidence for differential invocation of knowledge-based vs. strategic solution processes across different classes of problem, and it suggests that the conditions under which incubation can be used as a practical technique for enhancing problem solving must be designed with care. PMID:19210055
Analytical solution of the bosonic three-body problem.
Gogolin, Alexander O; Mora, Christophe; Egger, Reinhold
2008-04-11
We revisit the problem of three identical bosons in free space, which exhibits a universal hierarchy of bound states (Efimov trimers). Modeling a narrow Feshbach resonance within a two-channel description, we map the integral equation for the three-body scattering amplitude to a one-dimensional Schrödinger-type single-particle equation, where an analytical solution of exponential accuracy is obtained. We give exact results for the trimer binding energies, the three-body parameter, the threshold to the three-atom continuum, and the recombination rate. PMID:18518009
Trentacosta, Christopher J.; Fine, Sarah E.
2010-01-01
The present meta-analytic review examined the magnitude of the relation between discrete emotion knowledge and three of its most commonly studied correlates in childhood and adolescence: social competence, internalizing problems, and externalizing problems. Emotion knowledge demonstrated small to medium-sized relations with each correlate. Moderators of effect size were also examined and included multiple sample and methodological characteristics. Using random effects models, significant moderators of effect size for relations between emotion knowledge and externalizing problems included sample recruitment, sample age, and the source of externalizing problems ratings. Moderators of effect size were not found for emotion knowledge and social competence, and the effect sizes across samples for emotion knowledge and internalizing problems were homogeneous. Results highlight the relatively consistent yet modest relations between emotion knowledge and its correlates. Implications for applied research and new directions for research on emotion knowledge using innovative methods are discussed. PMID:21072259
Kramers problem: Numerical Wiener-Hopf-like model characteristics
NASA Astrophysics Data System (ADS)
Ezin, A. N.; Samgin, A. L.
2010-11-01
Since the Kramers problem cannot be, in general, solved in terms of elementary functions, various numerical techniques or approximate methods must be employed. We present a study of characteristics for a particle in a damped well, which can be considered as a discretized version of the Melnikov [Phys. Rev. E 48, 3271 (1993)]10.1103/PhysRevE.48.3271 turnover theory. The main goal is to justify the direct computational scheme to the basic Wiener-Hopf model. In contrast to the Melnikov approach, which implements factorization through a Cauchy-theorem-based formulation, we employ the Wiener-Levy theorem to reduce the Kramers problem to a Wiener-Hopf sum equation written in terms of Toeplitz matrices. This latter can provide a stringent test for the reliability of analytic approximations for energy distribution functions occurring in the Kramers problems at arbitrary damping. For certain conditions, the simulated characteristics are compared well with those determined using the conventional Fourier-integral formulas, but sometimes may differ slightly depending on the value of a dissipation parameter. Another important feature is that, with our method, we can avoid some complications inherent to the Melnikov method. The calculational technique reported in the present paper may gain particular importance in situations where the energy losses of the particle to the bath are a complex-shaped function of the particle energy and analytic solutions of desired accuracy are not at hand. In order to appreciate more readily the significance and scope of the present numerical approach, we also discuss concrete aspects relating to the field of superionic conductors.
Kramers problem: numerical Wiener-Hopf-like model characteristics.
Ezin, A N; Samgin, A L
2010-11-01
Since the Kramers problem cannot be, in general, solved in terms of elementary functions, various numerical techniques or approximate methods must be employed. We present a study of characteristics for a particle in a damped well, which can be considered as a discretized version of the Melnikov [Phys. Rev. E 48, 3271 (1993)] turnover theory. The main goal is to justify the direct computational scheme to the basic Wiener-Hopf model. In contrast to the Melnikov approach, which implements factorization through a Cauchy-theorem-based formulation, we employ the Wiener-Levy theorem to reduce the Kramers problem to a Wiener-Hopf sum equation written in terms of Toeplitz matrices. This latter can provide a stringent test for the reliability of analytic approximations for energy distribution functions occurring in the Kramers problems at arbitrary damping. For certain conditions, the simulated characteristics are compared well with those determined using the conventional Fourier-integral formulas, but sometimes may differ slightly depending on the value of a dissipation parameter. Another important feature is that, with our method, we can avoid some complications inherent to the Melnikov method. The calculational technique reported in the present paper may gain particular importance in situations where the energy losses of the particle to the bath are a complex-shaped function of the particle energy and analytic solutions of desired accuracy are not at hand. In order to appreciate more readily the significance and scope of the present numerical approach, we also discuss concrete aspects relating to the field of superionic conductors. PMID:21230615
Analytic model and frequency characteristics of plasma synthetic jet actuator
NASA Astrophysics Data System (ADS)
Zong, Hao-hua; Wu, Yun; Li, Ying-hong; Song, Hui-min; Zhang, Zhi-bo; Jia, Min
2015-02-01
This paper reports a novel analytic model of a plasma synthetic jet actuator (PSJA), considering both the heat transfer effect and the inertia of the throat gas. Both the whole cycle characteristics and the repetitive working process of PSJA can be predicted with this model. The frequency characteristics of a PSJA with 87 mm3 volume and different orifice diameters are investigated based on the analytic model combined with experiments. In the repetitive working mode, the actuator works initially in the transitional stage with 20 cycles and then in the dynamic balanced stage. During the transitional stage, major performance parameters of PSJA experience stepped growth, while during the dynamic balanced stage, these parameters are characterized by periodic variation. With a constant discharge energy of 6.9 mJ, there exists a saturated frequency of 4 kHz/6 kHz for an orifice diameter of 1 mm/1.5 mm, at which the time-averaged total pressure of the pulsed jet reaches a maximum. Between 0.5 mm and 1.5 mm, a larger orifice diameter leads to a higher saturated frequency due to the reduced jet duration time. As the actuation frequency increases, both the time-averaged cavity temperature and the peak jet velocity initially increase and then remain almost unchanged at 1600 K and 280 m/s, respectively. Besides, with increasing frequency, the mechanical energy incorporated in single pulsed jet, the expelled mass per pulse, and the time-averaged density in the cavity, decline in a stair stepping way, which is caused by the intermittent decrease of refresh stage duration in one period.
Konovalov, Aleksandr B; Vlasov, V V; Kalintsev, A G; Lyubimov, Vladimir V; Kravtsenyuk, Olga V
2006-11-30
The inverse problem of diffuse optical tomography (DOT) is reduced by the method of photon average trajectories (PAT) to the solution of the integral equation integrated along the conditional mean statistical photon trajectory. The PAT bending near the flat boundary of a scattering medium is estimated analytically. These estimates are used to determine the analytic statistical characteristics of photon trajectories for the flat layer geometry. The inverse DOT problem is solved by using the multiplicative algebraic algorithm modified to improve the convergence of the iteration reconstruction process. The numerical experiment shows that the modified PAT method permits the reconstruction of near-surface optical inhomogeneities virtually without distortions. (special issue devoted to multiple radiation scattering in random media)
Analytical and Numerical Studies of Several Fluid Mechanical Problems
NASA Astrophysics Data System (ADS)
Kong, D. L.
2014-03-01
In this thesis, three parts, each with several chapters, are respectively devoted to hydrostatic, viscous, and inertial fluids theories and applications. Involved topics include planetary, biological fluid systems, and high performance computing technology. In the hydrostatics part, the classical Maclaurin spheroids theory is generalized, for the first time, to a more realistic multi-layer model, establishing geometries of both the outer surface and the interfaces. For one of its astrophysical applications, the theory explicitly predicts physical shapes of surface and core-mantle-boundary for layered terrestrial planets, which enables the studies of some gravity problems, and the direct numerical simulations of dynamo flows in rotating planetary cores. As another application of the figure theory, the zonal flow in the deep atmosphere of Jupiter is investigated for a better understanding of the Jovian gravity field. An upper bound of gravity field distortions, especially in higher-order zonal gravitational coefficients, induced by deep zonal winds is estimated firstly. The oblate spheroidal shape of an undistorted Jupiter resulting from its fast solid body rotation is fully taken into account, which marks the most significant improvement from previous approximation based Jovian wind theories. High viscosity flows, for example Stokes flows, occur in a lot of processes involving low-speed motions in fluids. Microorganism swimming is such a typical case. A fully three dimensional analytic solution of incompressible Stokes equation is derived in the exterior domain of an arbitrarily translating and rotating prolate spheroid, which models a large family of microorganisms such as cocci bacteria. The solution is then applied to the magnetotactic bacteria swimming problem, and good consistency has been found between theoretical predictions and laboratory observations of the moving patterns of such bacteria under magnetic fields. In the analysis of dynamics of planetary
Characteristics of Problems for Problem-Based Learning: The Students' Perspective
ERIC Educational Resources Information Center
Sockalingam, Nachamma; Schmidt, Henk G.
2011-01-01
This study aimed to identify salient problem characteristics perceived by students in problem-based curricula. To this end, reflective essays from biomedical students (N = 34) on characteristics of good problems were text-analyzed. Students identified eleven characteristics, of which they found the extent to which the problem leads to desired…
Semi-analytic approach for electromagnetic problems of large arrays structures
NASA Astrophysics Data System (ADS)
Rostami-Angas, Masoud
There are limited electromagnetic problems which have closed form analytic solutions. Most of the real-world electromagnetic problems like electromagnetic scattering, electromagnetic radiation, waveguide modeling, etc., are not analytically calculable, because of the multitude of irregular geometries found in actual devices. Numerical computational techniques can be used as alternative method to overcome the inability of deriving closed form solutions of Maxwell's equations under various constitutive relations of media, and boundary conditions. This makes computational electromagnetics important in microwave, RF and photonic areas. Care must be taken into choosing the right method; otherwise the wrong method can either yield incorrect results, or results which take excessively long or demand great computational resources. Moreover, there are important electromagnetic problems for which numerical method solutions are challenging, if not impossible. Large non-periodic array of dipoles and multilayer spheres are examples of those problems. Some of these problems, because of their specific geometries and characteristics, can be modeled accurately and efficiently by applying Discrete Dipole Approximation (DDA), multipole expansion and translation addition theorem. The usual solution approach is to model the electromagnetic fields, or other unknowns, using multipole expansions, truncate appropriately the infinite summations, apply the boundary conditions, and then solve the resulting matrix problem by numerical methods. Because the approach contains both of analytic methods and numerical matrix solvers, it can be considered as a semi-analytic approach. The first chapter briefly describes the electromagnetic problems and semi-analytic approaches of this thesis. In the second chapter, a large array of molecular aggregates is investigated with the goal of solving the multiscale problem of a large array of molecules to explore its optical behaviors. Quantum electrodynamics
Asbestos quantification in track ballast, a complex analytical problem
NASA Astrophysics Data System (ADS)
Cavallo, Alessandro
2016-04-01
Track ballast forms the trackbeb upon which railroad ties are laid. It is used to bear the load from the railroad ties, to facilitate water drainage, and also to keep down vegetation. It is typically made of angular crushed stone, with a grain size between 30 and 60 mm, with good mechanical properties (high compressive strength, freeze - thaw resistance, resistance to fragmentation). The most common rock types are represented by basalts, porphyries, orthogneisses, some carbonatic rocks and "green stones" (serpentinites, prasinites, amphibolites, metagabbros). Especially "green stones" may contain traces, and sometimes appreciable amounts of asbestiform minerals (chrysotile and/or fibrous amphiboles, generally tremolite - actinolite). In Italy, the chrysotile asbestos mine in Balangero (Turin) produced over 5 Mt railroad ballast (crushed serpentinites), which was used for the railways in northern and central Italy, from 1930 up to 1990. In addition to Balangero, several other serpentinite and prasinite quarries (e.g. Emilia Romagna) provided the railways ballast up to the year 2000. The legal threshold for asbestos content in track ballast is established in 1000 ppm: if the value is below this threshold, the material can be reused, otherwise it must be disposed of as hazardous waste, with very high costs. The quantitative asbestos determination in rocks is a very complex analytical issue: although techniques like TEM-SAED and micro-Raman are very effective in the identification of asbestos minerals, a quantitative determination on bulk materials is almost impossible or really expensive and time consuming. Another problem is represented by the discrimination of asbestiform minerals (e.g. chrysotile, asbestiform amphiboles) from the common acicular - pseudo-fibrous varieties (lamellar serpentine minerals, prismatic/acicular amphiboles). In this work, more than 200 samples from the main Italian rail yards were characterized by a combined use of XRD and a special SEM
Overview of tritium: characteristics, sources, and problems.
Okada, S; Momoshima, N
1993-12-01
Tritium has certain characteristics that present unique challenges for dosimetry and health-risk assessment. For example, in the gas form, tritium can diffuse through almost any container, including those made of steel, aluminum, and plastics. In the oxide form, tritium can generally not be detected by commonly used survey instruments. In the environment, tritium can be taken up by all hydrogen-containing molecules, distributing widely on a global scale. Tritium can be incorporated into humans through respiration, ingestion, and diffusion through skin. Its harmful effects are observed only when it is incorporated into the body. Several sources contribute to the inventory of tritium in our environment. These are 1) cosmic ray interaction with atmospheric molecules; 2) nuclear reactions in the earth's crust; 3) nuclear testing in the atmosphere during the 1950s and 1960s; 4) continuous release of tritium from nuclear power plants and tritium production facilities under normal operation; 5) incidental releases from these facilities; and 6) consumer products. An important future source will be nuclear fusion facilities expected to be developed for the purpose of electricity generation. The principal health physics problems associated with tritium are 1) the determination of the parameters for risk estimation with further reduction of their uncertainties (e.g., relative biological effectiveness and dose-rate dependency); 2) risk estimation from complex exposures to tritium in gas form, tritium in oxide form, tritium surface contamination, and other tritium-contaminated forms, with or without other ionizing radiations and/or nonionizing radiations; 3) the dose contributions of elemental tritium in the lung and from its oxidized tritium in the gastrointestinal tract; 4) prevention of tritium (in oxide form) intake and enhancement of tritium (oxide form) excretion from the human body; 5) precise health effects information for low-level tritium exposure; and 6) public
Analytical Solution to the Riemann Problem of Three-Phase Flow in Porous Media
Juanes, Ruben; Patzek, Tadeusz W.
2002-09-26
In this paper we study one-dimensional three-phase flow through porous media of immiscible, incompressible fluids. The model uses the common multiphase flow extension of Darcy's equation, and does not include gravity and capillarity effects. Under these conditions, the mathematical problem reduces to a 2 x 2 system of conservation laws whose essential features are: (1) the system is strictly hyperbolic; (2) both characteristic fields are nongenuinely nonlinear, with single, connected inflection loci. These properties, which are natural extensions of the two-phase flow model, ensure that the solution is physically sensible. We present the complete analytical solution to the Riemann problem (constant initial and injected states) in detail, and describe the characteristic waves that may arise, concluding that only nine combinations of rarefactions, shocks and rarefaction-shocks are possible. We demonstrate that assuming the saturation paths of the solution are straightlines may result in inaccurate predictions for some realistic systems. Efficient algorithms for computing the exact solution are also given, making the analytical developments presented here readily applicable to interpretation of lab displacement experiments, and implementation of streamline simulators.
Nanomaterials in consumer products: a challenging analytical problem
NASA Astrophysics Data System (ADS)
Contado, Catia
2015-08-01
Many products used in everyday life are made with the assistance of nanotechnologies. Cosmetic, pharmaceuticals, sunscreen, powdered food are only few examples of end products containing nano-sized particles (NPs), generally added to improve the product quality. To evaluate correctly benefits versus risks of engineered nanomaterials and consequently to legislate in favor of consumer’s protection, it is necessary to know the hazards connected with the exposure levels. This information implies transversal studies and a number of different competences. On analytical point of view the identification, quantification and characterization of NPs in food matrices and in cosmetic or personal care products pose significant challenges, because NPs are usually present at low concentration levels and the matrices, in which they are dispersed, are complexes and often incompatible with analytical instruments that would be required for their detection and characterization. This paper focused on some analytical techniques suitable for the detection, characterization and quantification of NPs in food and cosmetics products, reports their recent application in characterizing specific metal and metal-oxide NPs in these two important industrial and market sectors. The need of a characterization of the NPs as much as possible complete, matching complementary information about different metrics, possible achieved through validate procedures, is what clearly emerges from this research. More work should be done to produce standardized materials and to set-up methodologies to determine number-based size distributions and to get quantitative date about the NPs in such a complex matrices.
Nanomaterials in consumer products: a challenging analytical problem
Contado, Catia
2015-01-01
Many products used in everyday life are made with the assistance of nanotechnologies. Cosmetic, pharmaceuticals, sunscreen, powdered food are only few examples of end products containing nano-sized particles (NPs), generally added to improve the product quality. To evaluate correctly benefits vs. risks of engineered nanomaterials and consequently to legislate in favor of consumer's protection, it is necessary to know the hazards connected with the exposure levels. This information implies transversal studies and a number of different competences. On analytical point of view the identification, quantification and characterization of NPs in food matrices and in cosmetic or personal care products pose significant challenges, because NPs are usually present at low concentration levels and the matrices, in which they are dispersed, are complexes and often incompatible with analytical instruments that would be required for their detection and characterization. This paper focused on some analytical techniques suitable for the detection, characterization and quantification of NPs in food and cosmetics products, reports their recent application in characterizing specific metal and metal-oxide NPs in these two important industrial and market sectors. The need of a characterization of the NPs as much as possible complete, matching complementary information about different metrics, possible achieved through validate procedures, is what clearly emerges from this research. More work should be done to produce standardized materials and to set-up methodologies to determine number-based size distributions and to get quantitative date about the NPs in such a complex matrices. PMID:26301216
Nanomaterials in consumer products: a challenging analytical problem.
Contado, Catia
2015-01-01
Many products used in everyday life are made with the assistance of nanotechnologies. Cosmetic, pharmaceuticals, sunscreen, powdered food are only few examples of end products containing nano-sized particles (NPs), generally added to improve the product quality. To evaluate correctly benefits vs. risks of engineered nanomaterials and consequently to legislate in favor of consumer's protection, it is necessary to know the hazards connected with the exposure levels. This information implies transversal studies and a number of different competences. On analytical point of view the identification, quantification and characterization of NPs in food matrices and in cosmetic or personal care products pose significant challenges, because NPs are usually present at low concentration levels and the matrices, in which they are dispersed, are complexes and often incompatible with analytical instruments that would be required for their detection and characterization. This paper focused on some analytical techniques suitable for the detection, characterization and quantification of NPs in food and cosmetics products, reports their recent application in characterizing specific metal and metal-oxide NPs in these two important industrial and market sectors. The need of a characterization of the NPs as much as possible complete, matching complementary information about different metrics, possible achieved through validate procedures, is what clearly emerges from this research. More work should be done to produce standardized materials and to set-up methodologies to determine number-based size distributions and to get quantitative date about the NPs in such a complex matrices. PMID:26301216
Constructive analytical solution of the evolution hill problem
NASA Astrophysics Data System (ADS)
Vashkov'yak, M. A.
2010-12-01
A new analytical solution of the system of differential equations describing secular perturbations and long-period solar perturbations of mean orbits of outer satellites of giant planets was obtained. As distinct from other solutions, the solution constructed using von Zeipel's method approximately takes into account, in the secular part of the perturbing function, the totality of fourth order with respect to the small parameter m of the ratio of the mean motions of the primary planet and the satellite. This enables us to describe more accurately the evolution of satellite orbits with large apocentric distances, which in the course of evolution may exceed the halved radius of the Hill sphere of the planet with respect to the Sun. Among these are the orbits of the two outermost Neptunian satellites N10 (Psamathe) and N13 (Neso). For these satellites, the parameter m amounts to 0.152 and 0.165, respectively. Different from a purely analytical solution, the proposed solution requires preliminary calculations for each satellite. More precisely, in doing so, we need to construct some simple functions to approximate more complex ones. This is why we use the phrase "constructive analytical." To illustrate the solution, we compare it with the results of the numerical integration of the strict motion equations of the satellites N10 and N13 over time intervals 5-15 thousand years.
Three-body quantum Coulomb problem: Analytic continuation
NASA Astrophysics Data System (ADS)
Turbiner, A. V.; Lopez Vieyra, J. C.; Olivares Pilón, H.
2016-08-01
The second (unphysical) critical charge in the three-body quantum Coulomb system of a nucleus of positive charge Z and mass mp, and two electrons, predicted by Stillinger has been calculated to be equal to ZB∞ = 0.904854 and ZBmp = 0.905138 for infinite and finite (proton) mass mp, respectively. It is shown that in both cases, the ground state energy E(Z) (analytically continued beyond the first critical charge Zc, for which the ionization energy vanishes, to ReZ
An analytical solution for the swing-by problem
NASA Astrophysics Data System (ADS)
Valsecchi, G. B.; Alessi, E. M.; Rossi, A.
2015-10-01
The extension of Öpik's theory of close encounters developed in the last decades allows a fully analytical, quantitative treatment of the motion of a small body encountering a massive perturber on a circular orbit. In this paper we derive explicit expressions for the initial values of the angular elements of the small body orbit, of given semimajor axis, eccentricity and inclination, in order to obtain a post-encounter orbit with prescribed values of semimajor axis, eccentricity and inclination. We describe the geometrical aspects of the algorithm, and give two examples of application; the first of them concerns the geometry of the 2029 Earth encounter of Apophis, while the second illustrates a sequence of close encounters with Callisto of the JUICE probe, aimed at changing the inclination of the spacecraft orbit. In the planning of complex space missions involving multiple encounters with planets or satellites, the algorithm described in the paper could provide a reliable initial guess to start the computationally intensive optimization process.
An analytical treatment of the swing-by problem.
NASA Astrophysics Data System (ADS)
Valsecchi, G. B.; Alessi, E. M.; Rossi, A.
In the framework of the extension of Öpik's theory of close encounters developed in the last decades, we make a fully analytical, quantitative treatment of the motion of a small body encountering a massive perturber on a circular orbit (Valsecchi et al. 2015a,b). We derive explicit expressions for the initial values of the angular elements of a small body orbit, of given semimajor axis a, eccentricity e, and inclination i, that are needed in order to obtain a post-encounter orbit with prescribed values of semimajor axis a', eccentricity e', and inclination i'. We discuss the geometrical aspects of the algorithm, and give two examples of application; the first one deals with the geometry of the 2029 Earth encounter of Apophis, while the second illustrates a sequence of close encounters with Callisto of the JUICE probe, aimed at changing the inclination of the spacecraft orbit. In planning complex space missions involving multiple encounters with planets or satellites, the algorithm described here could provide a reliable initial guess to start the computationally intensive optimization process.
An analytic method for the inverse problem of MREPT
NASA Astrophysics Data System (ADS)
Palamodov, V.
2016-03-01
Magnetic resonance electric properties tomography (MREPT) is a medical imaging modality for visualizing the electrical tissue properties of the human body using radio-frequency magnetic fields. This method consists of reconstructing the admittivity distribution from the positive rotating component of the magnetic field. In the newest paper of Ammari et al (2015 Inverse Problems 31 105001) an approximate method of reconstruction of variable admittivity was proposed. In this paper a method for exact reconstruction of the admittivity from data of the positive rotating component of the field is given.
ERIC Educational Resources Information Center
Cancilla, Devon A.
2001-01-01
Introduces an undergraduate level problem-based analytical chemistry laboratory course integrated with an environmental law course. Aims to develop an understanding among students on the use of environmental indicators for environmental evaluation. (Contains 30 references.) (YDS)
The "PIP problem": clinical and histologic characteristics.
Correia-Sá, Inês; Rodrigues-Pereira, Pedro; Marques, Marisa
2013-10-01
Implants from Poly Implant Prothése (PIP), the French manufacturer, showed increased risk of implant rupture and silicone leakage through the shell. Concerns also exist about the potential irritant behavior of silicone gel filler in these implants. This report presents the clinical, histologic, and microbiologic characteristics of a capsule and a siliconoma from a patient with a ruptured PIP implant. A 41-year-old woman submitted to breast augmentation in 2005 with PIP silicone gel implants presented with a recent history of progressive asymmetric breast enlargement and an enlarged lymph node on her right axilla. No capsular contracture was observed. A breast ultrasonography showed intra- and extracapsular ruptures of the right implant. The woman underwent explantation. Histologic analysis of the breast capsules showed a thin capsule with a chronic, mild inflammatory response. Microbiologic analysis showed no bacterial agent. The irritant behavior of the PIP silicone gel previously described was not able to produce capsular contracture or an exuberant inflammatory reaction. Studies to evaluate the potential risks of the silicone gel and to define the hazards for women implanted with those prostheses are urgently needed. PMID:23943050
NASA Astrophysics Data System (ADS)
Duffy, Brenton
The distinguishing characteristic of the elliptic restricted three-body problem from that of the circular case is a pulsating potential field resulting in non-autonomous and non-integrable spacecraft dynamics, which are difficult to model using classical methods of analysis. The purpose of this study is to harness modern methods of analytical perturbation theory to normalize the system dynamics about the circular restricted three-body problem and about one of the triangular Lagrange points. The normalization is achieved through a canonical transformation of the system Hamiltonian function based on the Lie transform method introduced by Hori and Deprit in the 1960s. The classic method derives a near-identity transformation of a Hamiltonian function expanded about a single parameter such that the transformed system possesses ideal properties of integrability. One of the major contributions of this study is to extend the normalization method to two-parameter expansions and to non-autonomous Hamiltonian systems. The two-parameter extension is used to normalize the system dynamics of the elliptic restricted three-body problem such that the stability of the triangular Lagrange points may be determined using the Kolmogorov-Arnold-Moser theorem. Further dynamical analysis is performed in the transformed phase space in terms of local integrals of motion akin to Jacobi's integral of the circular restricted three-body problem. The local phase space around the Lagrange point is foliated by invariant tori that effectively separate the planar dynamics into qualitative regions of motion. Additional analysis is presented for the incorporation of control into the normalization routine with the goal of eliminating the non-circular secular perturbations. The control method is validated on a test case and applied to the elliptic restricted three-body problem for the purposes of stabilizing the motion around the triangular Lagrange points.
Analytical derivation: An epistemic game for solving mathematically based physics problems
NASA Astrophysics Data System (ADS)
Bajracharya, Rabindra R.; Thompson, John R.
2016-06-01
Problem solving, which often involves multiple steps, is an integral part of physics learning and teaching. Using the perspective of the epistemic game, we documented a specific game that is commonly pursued by students while solving mathematically based physics problems: the analytical derivation game. This game involves deriving an equation through symbolic manipulations and routine mathematical operations, usually without any physical interpretation of the processes. This game often creates cognitive obstacles in students, preventing them from using alternative resources or better approaches during problem solving. We conducted hour-long, semi-structured, individual interviews with fourteen introductory physics students. Students were asked to solve four "pseudophysics" problems containing algebraic and graphical representations. The problems required the application of the fundamental theorem of calculus (FTC), which is one of the most frequently used mathematical concepts in physics problem solving. We show that the analytical derivation game is necessary, but not sufficient, to solve mathematically based physics problems, specifically those involving graphical representations.
The Contributions of Spatial, Verbal, and Analytical Skills to Problem-Solving Performance
ERIC Educational Resources Information Center
Foster, Ardyth C.
2012-01-01
The purpose of this study was to examine the existence and strength of relationships between students' cognitive skills and mathematical problem-solving performance. Specifically, relationships between students' verbal, spatial, and analytical skills and their problem-solving performance on items that require a verbal response, items…
ERIC Educational Resources Information Center
Pardue, Harry L.; Woo, Jannie
1984-01-01
Proposes an approach to teaching analytical chemistry and chemical analysis in which a problem to be resolved is the focus of a course. Indicates that this problem-oriented approach is intended to complement detailed discussions of fundamental and applied aspects of chemical determinations and not replace such discussions. (JN)
Analytical Derivation: An Epistemic Game for Solving Mathematically Based Physics Problems
ERIC Educational Resources Information Center
Bajracharya, Rabindra R.; Thompson, John R.
2016-01-01
Problem solving, which often involves multiple steps, is an integral part of physics learning and teaching. Using the perspective of the epistemic game, we documented a specific game that is commonly pursued by students while solving mathematically based physics problems: the "analytical derivation" game. This game involves deriving an…
The finite time multi-level SU(2) Landau-Zener problems: exact analytical results
NASA Astrophysics Data System (ADS)
Mkam Tchouobiap, S. E.; Kenmoe, M. B.; Fai, L. C.
2015-10-01
The multi-level SU(2) Landau-Zener problem is analytically solved at finite time within the framework of the Bloch tensor formalism and with the help of the disentanglement Wei-Norman ordering technique. A generalized and exact analytical solution is achieved that accounts not only for all projections of an arbitrary spin S along the Zeeman field direction but also for non-adiabatic and adiabatic evolutions.
An analytical procedure for evaluating shuttle abort staging aerodynamic characteristics
NASA Technical Reports Server (NTRS)
Meyer, R.
1973-01-01
An engineering analysis and computer code (AERSEP) for predicting Space Shuttle Orbiter - HO Tank longitudinal aerodynamic characteristics during abort separation has been developed. Computed results are applicable at Mach numbers above 2 for angle-of-attack between plus or minus 10 degrees. No practical restrictions on orbiter-tank relative positioning are indicated for tank-under-orbiter configurations. Input data requirements and computer running times are minimal facilitating program use for parametric studies, test planning, and trajectory analysis. In a majority of cases AERSEP Orbiter-Tank interference predictions are as accurate as state-of-the-art estimates for interference-free or isolated-vehicle configurations. AERSEP isolated-orbiter predictions also show excellent correlation with data.
NASA Astrophysics Data System (ADS)
Zingerman, K. M.; Shavyrin, D. A.
2016-06-01
The approximate analytical solution of a quasi-static plane problem of the theory of viscoelasticity is obtained under finite strains. This is the problem of the stress-strain state in an infinite body with circular viscoelastic inclusion. The perturbation technique, Laplace transform, and complex Kolosov-Muskhelishvili's potentials are used for the solution. The numerical results are presented. The nonlinear effects and the effects of viscosity are estimated.
Analytical solution of boundary integral equations for 2-D steady linear wave problems
NASA Astrophysics Data System (ADS)
Chuang, J. M.
2005-10-01
Based on the Fourier transform, the analytical solution of boundary integral equations formulated for the complex velocity of a 2-D steady linear surface flow is derived. It has been found that before the radiation condition is imposed, free waves appear both far upstream and downstream. In order to cancel the free waves in far upstream regions, the eigensolution of a specific eigenvalue, which satisfies the homogeneous boundary integral equation, is found and superposed to the analytical solution. An example, a submerged vortex, is used to demonstrate the derived analytical solution. Furthermore, an analytical approach to imposing the radiation condition in the numerical solution of boundary integral equations for 2-D steady linear wave problems is proposed.
Li, Rui; Wang, Pengcheng; Tian, Yu; Wang, Bo; Li, Gang
2015-01-01
A unified analytic solution approach to both static bending and free vibration problems of rectangular thin plates is demonstrated in this paper, with focus on the application to corner-supported plates. The solution procedure is based on a novel symplectic superposition method, which transforms the problems into the Hamiltonian system and yields accurate enough results via step-by-step rigorous derivation. The main advantage of the developed approach is its wide applicability since no trial solutions are needed in the analysis, which is completely different from the other methods. Numerical examples for both static bending and free vibration plates are presented to validate the developed analytic solutions and to offer new numerical results. The approach is expected to serve as a benchmark analytic approach due to its effectiveness and accuracy. PMID:26608602
ERIC Educational Resources Information Center
Boyce, Mary C.; Singh, Kuki
2008-01-01
This paper describes a student-focused activity that promotes effective learning in analytical chemistry. Providing an environment where students were responsible for their own learning allowed them to participate at all levels from designing the problem to be addressed, planning the laboratory work to support their learning, to providing evidence…
A Multilevel Analysis of Problem-Based Learning Design Characteristics
ERIC Educational Resources Information Center
Scott, Kimberly S.
2014-01-01
The increasing use of experience-centered approaches like problem-based learning (PBL) by learning and development practitioners and management educators has raised interest in how to design, implement and evaluate PBL in that field. Of particular interest is how to evaluate the relative impact of design characteristics that exist at the…
Problem Gambling in Chinese American Adolescents: Characteristics and Risk Factors
ERIC Educational Resources Information Center
Chiu, Eddie Yu-Wai; Woo, Kent
2012-01-01
This preliminary study examined the characteristics and risk factors of problem gambling among Chinese American adolescents. A total of 192 Chinese American students (aged 13-19) from 9th to 12th grades were recruited from three high schools in San Francisco, California. Students were administered the South Oaks Gambling Screen Revised for…
Client Engagement Characteristics Associated with Problem Gambling Treatment Outcomes
ERIC Educational Resources Information Center
Dowling, Nicki A.; Cosic, Sanja
2011-01-01
Previous research examining the factors associated with problem gambling treatment outcomes has examined client factors and to date, treatment characteristics, therapist factors, and client-therapist interactions have essentially remained unexplored. This study aimed to investigate how client engagement variables (client-rated therapeutic…
Fast and accurate analytical model to solve inverse problem in SHM using Lamb wave propagation
NASA Astrophysics Data System (ADS)
Poddar, Banibrata; Giurgiutiu, Victor
2016-04-01
Lamb wave propagation is at the center of attention of researchers for structural health monitoring of thin walled structures. This is due to the fact that Lamb wave modes are natural modes of wave propagation in these structures with long travel distances and without much attenuation. This brings the prospect of monitoring large structure with few sensors/actuators. However the problem of damage detection and identification is an "inverse problem" where we do not have the luxury to know the exact mathematical model of the system. On top of that the problem is more challenging due to the confounding factors of statistical variation of the material and geometric properties. Typically this problem may also be ill posed. Due to all these complexities the direct solution of the problem of damage detection and identification in SHM is impossible. Therefore an indirect method using the solution of the "forward problem" is popular for solving the "inverse problem". This requires a fast forward problem solver. Due to the complexities involved with the forward problem of scattering of Lamb waves from damages researchers rely primarily on numerical techniques such as FEM, BEM, etc. But these methods are slow and practically impossible to be used in structural health monitoring. We have developed a fast and accurate analytical forward problem solver for this purpose. This solver, CMEP (complex modes expansion and vector projection), can simulate scattering of Lamb waves from all types of damages in thin walled structures fast and accurately to assist the inverse problem solver.
Fast multigrid solution of the advection problem with closed characteristics
Yavneh, I.; Venner, C.H.; Brandt, A.
1996-12-31
The numerical solution of the advection-diffusion problem in the inviscid limit with closed characteristics is studied as a prelude to an efficient high Reynolds-number flow solver. It is demonstrated by a heuristic analysis and numerical calculations that using upstream discretization with downstream relaxation-ordering and appropriate residual weighting in a simple multigrid V cycle produces an efficient solution process. We also derive upstream finite-difference approximations to the advection operator, whose truncation terms approximate {open_quotes}physical{close_quotes} (Laplacian) viscosity, thus avoiding spurious solutions to the homogeneous problem when the artificial diffusivity dominates the physical viscosity.
A multigroup radiation diffusion test problem: Comparison of code results with analytic solution
Shestakov, A I; Harte, J A; Bolstad, J H; Offner, S R
2006-12-21
We consider a 1D, slab-symmetric test problem for the multigroup radiation diffusion and matter energy balance equations. The test simulates diffusion of energy from a hot central region. Opacities vary with the cube of the frequency and radiation emission is given by a Wien spectrum. We compare results from two LLNL codes, Raptor and Lasnex, with tabular data that define the analytic solution.
NASA Astrophysics Data System (ADS)
Kharin, Stanislav N.; Sarsengeldin, Merey M.; Nouri, Hassan
2016-08-01
On the base of the Holm model, we represent two phase spherical Stefan problem and its analytical solution, which can serve as a mathematical model for diverse thermo-physical phenomena in electrical contacts. Suggested solution is obtained from integral error function and its properties which are represented in the form of series whose coefficients have to be determined. Convergence of solution series is proved.
Psychological Characteristics of Problem Gamblers With and Without Mood Disorder
Lister, Jamey J; Milosevic, Aleks; Ledgerwood, David M
2015-01-01
Objective: Problem and pathological gamblers are significantly more likely to experience mood disorders, compared with the general population. Our study examined the relation of psychological characteristics (personality, trait impulsiveness, and gambling motives) to current co-occurring mood disorder (major depression and dysthymia) status among problem and pathological gamblers. Method: Problem and pathological gamblers (N = 150) underwent a clinical interview to assess current co-occurring mood disorders; participants completed measures of problem gambling severity, personality, impulsiveness, and gambling motives. Results: Problem and pathological gamblers with a current co-occurring mood disorder were more likely to be female, older, and to report higher lifetime and past-year gambling severity. A co-occurring mood disorder was associated with higher personality scores for alienation and stress reaction, lower scores for well-being, social closeness, and control, as well as higher impulsiveness scores for urgency and lack of premeditation, and lower sensation seeking scores. Participants with a co-occurring mood disorder also reported higher coping motives for gambling. Multivariate logistic regression analyses demonstrated that personality factors (lower social closeness and higher alienation) contributed to the greatest likelihood of being diagnosed with a co-occurring mood disorder. Conclusions: Mood disorders frequently co-occur with problem and pathological gambling, and they are associated with greater gambling severity. These findings highlight that interpersonal facets of personality contribute substantially to co-occurring mood disorder status. Implications for treatment will be discussed. PMID:26454559
Analytical solution to a fracture problem in a tough layered structure
NASA Astrophysics Data System (ADS)
Hamamoto, Yukari; Okumura, Ko
2008-08-01
Nacre causes the shining beauty of pearl due to its remarkable layered structure, which is also strong. We reconsider a simplified layered model of nacre proposed previously [Okumura and de Gennes, Eur. Phys. J. E 4, 121 (2001)] and obtain an analytical solution to a fundamental crack problem. The result asserts that the fracture toughness is enhanced due to a large displacement around the crack tip (even if the crack-tip stress is not reduced). The derivation offers ideas for solving a number of boundary problems for partial differential equations important in many fields.
NASA Technical Reports Server (NTRS)
Eberle, W. R.
1981-01-01
A computer program to calculate the wake downwind of a wind turbine was developed. Turbine wake characteristics are useful for determining optimum arrays for wind turbine farms. The analytical model is based on the characteristics of a turbulent coflowing jet with modification for the effects of atmospheric turbulence. The program calculates overall wake characteristics, wind profiles, and power recovery for a wind turbine directly in the wake of another turbine, as functions of distance downwind of the turbine. The calculation procedure is described in detail, and sample results are presented to illustrate the general behavior of the wake and the effects of principal input parameters.
Analytical techniques for the evaluation of asymptotic matrix elements in electromagnetic problems
NASA Astrophysics Data System (ADS)
Park, Seong-Ook
1997-07-01
Analytical solutions of the asymptotic part of impedance matrix elements, whose integrand contains either a singularity or exhibits a strongly oscillatory behavior, are developed for the analysis of various geometries. These developed formulas are applied using the Method of Moments (MoM), to the analysis of wire antennas, planar transmission lines, and printed circuits including microstrip dipoles, asymmetric gap discontinuities, and arbitrary shapes of planar circuits, where computational speed and accuracy are important. The first example considered is the singularity treatment in integrands of wire-type antenna problems. To overcome the problem, first the singularity is subtracted out, and then this part is integrated analytically in the transform domain. Asymptotic matrix elements of the multilayer planar transmission lines are solved analytically by using Chebyshev polynomial basis functions in the spectral domain. These results are applied to open and coupled microstrip lines. The analysis of printed circuits involves Sommerfeld-type integrals which are extremely difficult to evaluate. To enhance the speed and accuracy of Sommerfeld-type integrals, this dissertation, for the first time, presents an analytical transformation technique. This formulation allows the infinite double integral of the asymptotic part of the impedance matrix to be transformed into a finite one-dimensional integral. Using this approach, the asymptotic part of self and mutual interactions between the triangular edge mode basis functions, along an electrically narrow strip, is solved analytically. These results are applied to microstrip dipoles and asymmetric gap discontinuities. This formula provides highly accurate results with minimal computational effort. This work is also extended to roof- top subdomain basis functions, and the obtained results can be used to solve arbitrarily shaped planar geometries. As an example, computed results of the Radar Cross Section (RCS) of a microstrip
ERIC Educational Resources Information Center
Sockalingam, Nachamma; Rotgans, Jerome I.; Schmidt, Henk G.
2011-01-01
This study investigated the influence of five problem characteristics on students' achievement-related classroom behaviors and academic achievement. Data from 5,949 polytechnic students in PBL curricula across 170 courses were analyzed by means of path analysis. The five problem characteristics were: (1) problem clarity, (2) problem familiarity,…
Statistical Mechanics of a Simplified Bipartite Matching Problem: An Analytical Treatment
NASA Astrophysics Data System (ADS)
Dell'Erba, Matías Germán
2012-03-01
We perform an analytical study of a simplified bipartite matching problem in which there exists a constant matching energy, and both heterosexual and homosexual pairings are allowed. We obtain the partition function in a closed analytical form and we calculate the corresponding thermodynamic functions of this model. We conclude that the model is favored at high temperatures, for which the probabilities of heterosexual and homosexual pairs tend to become equal. In the limits of low and high temperatures, the system is extensive, however this property is lost in the general case. There exists a relation between the matching energies for which the system becomes more stable under external (thermal) perturbations. As the difference of energies between the two possible matches increases the system becomes more ordered, while the maximum of entropy is achieved when these energies are equal. In this limit, there is a first order phase transition between two phases with constant entropy.
On the dyadic scattering problem in three-dimensional gradient elasticity: an analytic approach
NASA Astrophysics Data System (ADS)
Charalambopoulos, Antonios; Gergidis, Leonidas N.
2008-10-01
The investigation of the direct scattering problem of an elastic dyadic incident field from a spherical inclusion, is the main outcome of this work, in the case where the scatterer and the host environment dispose microstructure. The framework of the method is based on the implication of Mindlin's gradient theory. The development of the method is fully analytic and gives successively several byproducts, which are indispensable for the solution of the scattering problem but constitute also independent results of their own theoretical and practical value. So the numerable set of Navier eigendyadics is constructed, which is proved to be a basis for every dyadic field obeying the dynamic gradient elasticity equation. This permits the construction of a useful spectral representation for every gradient elasticity field. Furthermore, the set of dyadic spherical harmonics is built, which stands for the extension of the well-known spherical vector harmonics to the dyadic realm. Every dyadic field restricted on the unit sphere can be expanded in terms of these spherical dyadic harmonics. The orthogonality relations of these functions are determined in close form and this is the prerequisite for the fully analytic treatment of the boundary conditions involving the scattering problem under consideration.
Complete analytical solution of electromagnetic field problem of high-speed spinning ball
NASA Astrophysics Data System (ADS)
Reichert, T.; Nussbaumer, T.; Kolar, J. W.
2012-11-01
In this article, a small sphere spinning in a rotating magnetic field is analyzed in terms of the resulting magnetic flux density distribution and the current density distribution inside the ball. From these densities, the motor torque and the eddy current losses can be calculated. An analytical model is derived, and its results are compared to a 3D finite element analysis. The model gives insight into the torque and loss characteristics of a solid rotor induction machine setup, which aims at rotating the sphere beyond 25 Mrpm.
NASA Technical Reports Server (NTRS)
Allen, J. M.
1981-01-01
Techniques to predict the aerodynamic characteristics of slender cruciform missiles have been developed and are constantly being updated and improved. This paper presents comparisons between analytical and experimental supersonic aerodynamic data for a class of canard-controlled missile configurations similar to the sidewinder missile. Three aerodynamic prediction computer codes, including program MISSILE2, a recently improved version of program MISSILE, are evaluated by comparison with the test data to assess their accuracy. The major emphasis is placed on the roll control characteristics. In addition, tail span optimization, longitudinal and lateral control, induced roll, and missile roll orientation effects are addressed.
NASA Astrophysics Data System (ADS)
Tuzkaya, Umut R.; Eser, Arzum; Argon, Goner
2004-02-01
Today, growing amounts of waste due to fast consumption rate of products started an irreversible environmental pollution and damage. A considerable part of this waste is caused by packaging material. With the realization of this fact, various waste policies have taken important steps. Here we considered a firm, where waste Aluminum constitutes majority of raw materials for this fir0m. In order to achieve a profitable recycling process, plant layout should be well designed. In this study, we propose a two-step approach involving Analytic Hierarchy Process (AHP) and Data Envelopment Analysis (DEA) to solve facility layout design problems. A case example is considered to demonstrate the results achieved.
Analytical Solutions of Heat-Conduction Problems with Time-Varying Heat-Transfer Coefficients
NASA Astrophysics Data System (ADS)
Kudinov, V. A.; Eremin, A. V.; Stefanyuk, E. V.
2015-05-01
The problem on heat conduction of an infinite plate with a heat-transfer coefficient changing linearly with time for third-kind boundary conditions was solved analytically based on determination of the front of a temperature disturbance in this plate and introduction of additional boundary conditions. On the basis of the solution obtained, graphs of the distribution of isotherms in the indicated plate and the velocities of their movement along a spatial variable in it were constructed. As a result of the solution of the inverse problem on the heat conduction of the infinite plate with the use of the results of numerical calculation of the change in its temperature at any point on the indicated spatial coordinate, the Predvoditelev number was identified with an accuracy of 2%, which made it possible to determine the time dependence of the heat-transfer coefficient of the plate.
A linear analytical boundary element method (BEM) for 2D homogeneous potential problems
NASA Astrophysics Data System (ADS)
Friedrich, Jürgen
2002-06-01
The solution of potential problems is not only fundamental for geosciences, but also an essential part of related subjects like electro- and fluid-mechanics. In all fields, solution algorithms are needed that should be as accurate as possible, robust, simple to program, easy to use, fast and small in computer memory. An ideal technique to fulfill these criteria is the boundary element method (BEM) which applies Green's identities to transform volume integrals into boundary integrals. This work describes a linear analytical BEM for 2D homogeneous potential problems that is more robust and precise than numerical methods because it avoids numerical schemes and coordinate transformations. After deriving the solution algorithm, the introduced approach is tested against different benchmarks. Finally, the gained method was incorporated into an existing software program described before in this journal by the same author.
ERIC Educational Resources Information Center
Yoon, Heojeong; Woo, Ae Ja; Treagust, David; Chandrasegaran, A. L.
2014-01-01
The efficacy of problem-based learning (PBL) in an analytical chemistry laboratory course was studied using a programme that was designed and implemented with 20 students in a treatment group over 10 weeks. Data from 26 students in a traditional analytical chemistry laboratory course were used for comparison. Differences in the creative thinking…
Experimental and analytical comparison of aerodynamic characteristics of a forward-control missile
NASA Technical Reports Server (NTRS)
Blair, A. B.; Rapp, G. H.
1980-01-01
Comparisons of analytical and experimental aerodynamic data for canard controlled missile configurations are presented. Recently, techniques to estimate the longitudinal, directional and lateral aerodynamic characteristics for cruciform missiles have been developed. Nielsen Engineering and Research, Inc. (NEAR, Inc.), supported by various governmental agencies, has been the originator of many of these new computational techniques. Two of these are major computer programs currently being implemented by several research organizations. Predicted data from these two programs are compared with experimental data recently obtained at the NASA Langley Research Center Unitary Plan wind tunnel facility. Comparisons cover the supersonic Mach number regime of 1.60 to 3.50, angles-of-attack from 0 to 20 degrees and roll angles of 0, 26.57 and 45 degrees. Major emphasis is on the roll characteristics due to aileron with limited longitudinal and directional characteristics addressed.
NASA Astrophysics Data System (ADS)
Broman, Karolina; Bernholt, Sascha; Parchmann, Ilka
2015-05-01
found successful to analyse both the test items as well as students' responses in a systematic way. The framework can therefore be applied in the design of new tasks, the analysis and assessment of students' responses, and as a tool for teachers to scaffold students in their problem-solving process. Conclusions:This paper gives implications for practice and for future research to both develop new context-based problems in a structured way, as well as providing analytical tools for investigating students' higher order thinking in their responses to these tasks.
Analytical beam-width characteristics of distorted cat-eye reflected beam
NASA Astrophysics Data System (ADS)
Zhao, Yanzhong; Shan, Congmiao; Zheng, Yonghui; Zhang, Laixian; Sun, Huayan
2015-02-01
The analytical expression of beam-width of distorted cat-eye reflected beam under far-field condition is deduced using the approximate three-dimensional analytical formula for oblique detection laser beam passing through cat-eye optical lens with center shelter, and using the definition of second order moment, Gamma function and integral functions. The laws the variation of divergence angle and astigmatism degree of the reflected light with incident angle, focal shift, aperture size, and center shelter ratio are established by numerical calculation, and physical analysis. The study revealed that the cat-eye reflected beam is like a beam transmitted and collimated by the target optical lens, and has the same characteristics as that of Gaussian beam. A proper choice of positive focal shift would result in a divergence angle smaller than that of no focal shift. The astigmatism is mainly caused by incidence angle.
Smith, Douglas R; Moy, Marie A; Dolan, Anthony R; Wood, Troy D
2006-04-01
As miniaturization of electrospray continues to become more prevalent in the mass spectrometry arsenal, numerous types of conductive coatings have been developed with miniaturized electrospray emitters. Different conductive coatings have different properties that may lead to differences in analytical performance. This paper investigates and compares the analytical properties of a series of applied conductive coatings for low-flow electrospray ionization developed in this laboratory vs. commercially-available types. Evaporated graphite is thoroughly compared with commercially available polyaniline (PANI) coated emitters and metal coated emitters. Each set of emitters was investigated to determine various performance characteristics, including susceptibility to electrical discharge in both positive and negative ionization modes, as well as emitter reproducibility and generation of a standard curve to determine each emitter coating's limit of detection and limit of quantitation. Furthermore, evaporated graphite and polyaniline coated fused silica capillaries were investigated to determine which coating is more stable over long-term analyses and during electrical discharge. PMID:16568172
NASA Technical Reports Server (NTRS)
Fasanella, E. L.; Mcgehee, J. R.; Pappas, M. S.
1977-01-01
An experimental and analytical investigation was conducted to determine which characteristics of a light aircraft landing gear influence gear dynamic behavior significantly. The investigation focused particularly on possible modification for load control. Pseudostatic tests were conducted to determine the gear fore-and-aft spring constant, axial friction as a function of drag load, brake pressure-torque characteristics, and tire force-deflection characteristics. To study dynamic tire response, vertical drops were conducted at impact velocities of 1.2, 1.5, and 1.8 m/s onto a level surface; to determine axial-friction effects, a second series of vertical drops were made at 1.5 m/s onto surfaces inclined 5 deg and 10 deg to the horizontal. An average dynamic axial-friction coefficient of 0.15 was obtained by comparing analytical data with inclined surface drop test data. Dynamic strut bending and associated axial friction were found to be severe for the drop tests on the 10 deg surface.
Analytical solutions to general anti-plane shear problems in finite elasticity
NASA Astrophysics Data System (ADS)
Gao, David Yang
2016-03-01
This paper presents a pure complementary energy variational method for solving a general anti-plane shear problem in finite elasticity. Based on the canonical duality-triality theory developed by the author, the nonlinear/nonconvex partial differential equations for the large deformation problem are converted into an algebraic equation in dual space, which can, in principle, be solved to obtain a complete set of stress solutions. Therefore, a general analytical solution form of the deformation is obtained subjected to a compatibility condition. Applications are illustrated by examples with both convex and nonconvex stored strain energies governed by quadratic-exponential and power-law material models, respectively. Results show that the nonconvex variational problem could have multiple solutions at each material point, the complementary gap function and the triality theory can be used to identify both global and local extremal solutions, while the popular convexity conditions (including rank-one condition) provide mainly local minimal criteria and the Legendre-Hadamard condition (i.e., the so-called strong ellipticity condition) does not guarantee uniqueness of solutions. This paper demonstrates again that the pure complementary energy principle and the triality theory play important roles in finite deformation theory and nonconvex analysis.
On the location selection problem using analytic hierarchy process and multi-choice goal programming
NASA Astrophysics Data System (ADS)
Ho, Hui-Ping; Chang, Ching-Ter; Ku, Cheng-Yuan
2013-01-01
Location selection is a crucial decision in cost/benefit analysis of restaurants, coffee shops and others. However, it is difficult to be solved because there are many conflicting multiple goals in the problem of location selection. In order to solve the problem, this study integrates analytic hierarchy process (AHP) and multi-choice goal programming (MCGP) as a decision aid to obtain an appropriate house from many alternative locations that better suit the preferences of renters under their needs. This study obtains weights from AHP and implements it upon each goal using MCGP for the location selection problem. According to the function of multi-aspiration provided by MCGP, decision makers can set multi-aspiration for each location goal to rank the candidate locations. Compared to the unaided selection processes, the integrated approach of AHP and MCGP is a better scientific and efficient method than traditional methods in finding a suitable location for buying or renting a house for business, especially under multiple qualitative and quantitative criteria within a shorter evaluation time. In addition, a real case is provided to demonstrate the usefulness of the proposed method. The results show that the proposed method is able to provide better quality decision than normal manual methods.
NASA Astrophysics Data System (ADS)
Cancilla, Devon A.
2001-12-01
Environmental chemists face difficult challenges related to generating, interpreting, and communicating complex chemical data in a manner understandable by nonchemists. For this reason, it is essential that environmental chemistry students develop the skills necessary not only to collect and interpret complex data sets, but also to communicate their findings in a credible manner in nonscientific forums. Key to this requirement is an understanding of the quality assurance/quality control (QA/QC) elements used to support specific findings. This paper describes the development of a problem-based undergraduate environmental analytical chemistry laboratory and its integration with an undergraduate environmental law course. The course is designed to introduce students to the principles of performance-based analytical methods and the use of environmental indicators to perform environmental assessments. Conducting a series of chemical and toxicological tests, chemistry students perform an environmental assessment on the watershed of the mythical City of Rowan. Law students use these assessments to develop legal arguments under both the Safe Drinking Water Act and the Clean Water Act.
Analytical solutions and numerical modeling for a dam-break problem in inclined channels
NASA Astrophysics Data System (ADS)
Pelinovsky, Efim; Didenkulova, Ira; Didenkulov, Oleg; Rodin, Artem
2016-04-01
Here we obtain different analytical solutions of the shallow-water equations for inviscid nonlinear waves in inclined channels. (i) The first solution describes Riemann wave moving up or down alone the channel slope. It requires the initial fluid flow, which often accompanies waves generated by landslides. This solution is valid for a finite time before the wave breaks. (ii) The second solution generalizes the classical dam-break problem for the case of a dam located in the inclined channel. In this case the cross-section of the channel influences the speed of wave propagation inside the channel, and therefore changes wave dynamics inside the channel compare to the plane beach. (iii) The third solution describes the intermediate stage of the wave front dynamics for a dam of a large height. This solution is derived with the use of generalized Carrier-Greenspan approach developed early by Didenkulova & Pelinovsky (2011) and Rybkin et al (2014). Some of the analytical solutions are tested with the means of numerical modeling. The numerical modeling is carried out using the CLAWPACK software based on nonlinear shallow water equations. Application of the described solutions to possible laboratory experiments is discussed.
An analytical approach to estimate the number of small scatterers in 2D inverse scattering problems
NASA Astrophysics Data System (ADS)
Fazli, Roohallah; Nakhkash, Mansor
2012-07-01
This paper presents an analytical method to estimate the location and number of actual small targets in 2D inverse scattering problems. This method is motivated from the exact maximum likelihood estimation of signal parameters in white Gaussian noise for the linear data model. In the first stage, the method uses the MUSIC algorithm to acquire all possible target locations and in the next stage, it employs an analytical formula that works as a spatial filter to determine which target locations are associated to the actual ones. The ability of the method is examined for both the Born and multiple scattering cases and for the cases of well-resolved and non-resolved targets. Many numerical simulations using both the coincident and non-coincident arrays demonstrate that the proposed method can detect the number of actual targets even in the case of very noisy data and when the targets are closely located. Using the experimental microwave data sets, we further show that this method is successful in specifying the number of small inclusions.
NASA Technical Reports Server (NTRS)
Romanofsky, Robert R.
1989-01-01
In this report, a thorough analytical procedure is developed for evaluating the frequency-dependent loss characteristics and effective permittivity of microstrip lines. The technique is based on the measured reflection coefficient of microstrip resonator pairs. Experimental data, including quality factor Q, effective relative permittivity, and fringing for 50-omega lines on gallium arsenide (GaAs) from 26.5 to 40.0 GHz are presented. The effects of an imperfect open circuit, coupling losses, and loading of the resonant frequency are considered. A cosine-tapered ridge-guide text fixture is described. It was found to be well suited to the device characterization.
Friedman, Ronald S; Förster, Jens
2005-02-01
In 4 experiments, participants were led to focus on either the prospect of positive outcomes (approach anticipation) or the prospect of negative outcomes (avoidance anticipation) and were subsequently administered behavioral measures of relative hemispheric activation. It was found that approach, relative to avoidance-related anticipatory states, produced greater relative right (diminished relative left) hemispheric activation. Experiment 3 additionally demonstrated that this pattern of activation was reversed when approach and avoidance states were not merely anticipatory but were also emotionally arousing. Finally, Experiment 4 replicated earlier findings demonstrating an influence of approach and avoidance anticipatory states on creativity and analytical problem solving (R. S. Friedman & J. Forster, 2001, 2003) and provided evidence that such effects are mediated by differences in relative hemispheric activation. PMID:15841858
NASA Technical Reports Server (NTRS)
Landrum, E. J.; Miller, D. S.
1980-01-01
Trends toward the automation of the design process for airplanes and missiles accentuate the need for analytic techniques for the prediction of aerodynamic characteristics. A number of computer codes have been developed or are under development which show promise of significantly improving the estimation of aerodynamic characteristics for arbitrarily-shaped bodies at supersonic speeds. The programs considered range in complexity from a simple linearized solution employing slender body theory to an exact finite difference solution of the Euler equations. The results from five computer codes are compared with experimental data to determine the accuracy, range of applicability, ease of use, and computer time and cost of the programs. The results provide a useful guide for selecting the appropriate method for treating bodies at the various levels of an automated design process.
NASA Astrophysics Data System (ADS)
Bayón, L.; Grau, J. M.; Ruiz, M. M.; Suárez, P. M.
2012-12-01
One of the most well-known problems in the field of Microeconomics is the Firm's Cost-Minimization Problem. In this paper we establish the analytical expression for the cost function using the Cobb-Douglas model and considering maximum constraints for the inputs. Moreover we prove that it belongs to the class C1.
Analytical Characteristics of a Noninvasive Gene Expression Assay for Pigmented Skin Lesions.
Yao, Zuxu; Allen, Talisha; Oakley, Margaret; Samons, Carol; Garrison, Darryl; Jansen, Burkhard
2016-08-01
We previously reported clinical performance of a novel noninvasive and quantitative PCR (qPCR)-based molecular diagnostic assay (the pigmented lesion assay; PLA) that differentiates primary cutaneous melanoma from benign pigmented skin lesions through two target gene signatures, LINC00518 (LINC) and preferentially expressed antigen in melanoma (PRAME). This study focuses on analytical characterization of this PLA, including qPCR specificity and sensitivity, optimization of RNA input in qPCR to achieve a desired diagnostic sensitivity and specificity, and analytical performance (repeatability and reproducibility) of this two-gene PLA. All target qPCRs demonstrated a good specificity (100%) and sensitivity (with a limit of detection of 1-2 copies), which allows reliable detection of gene expression changes of LINC and PRAME between melanomas and nonmelanomas. Through normalizing RNA input in qPCR, we converted the traditional gene expression analyses to a binomial detection of gene transcripts (i.e., detected or not detected). By combining the binomial qPCR results of the two genes, an improved diagnostic sensitivity (raised from 52%- 65% to 71% at 1 pg of total RNA input, and to 91% at 3 pg of total RNA input) was achieved. This two-gene PLA demonstrates a high repeatability and reproducibility (coefficient of variation <3%) and all required analytical performance characteristics for the commercial processing of clinical samples. PMID:27505074
NASA Technical Reports Server (NTRS)
Lake, Renee C.; Izadpanah, Amir P.; Baucom, Robert M.
1993-01-01
The results from a study aimed at improving the dynamic and aerodynamic characteristics of composite rotor blades through the use of extension-twist coupling are presented. A set of extension-twist-coupled composite spars was manufactured with four plies of graphite-epoxy cloth prepreg. These spars were noncircular in cross-section design and were therefore subject to warping deformations. Three different cross-sectional geometries were developed: D-shape, square, and flattened ellipse. Three spars of each type were fabricated to assess the degree of repeatability in the manufacturing process of extension-twist-coupled structures. Results from free-free vibration tests of the spars were compared with results from normal modes and frequency analyses of companion shell-finite-element models. Five global modes were identified within the frequency range from 0 to 2000 Hz for each spar. The experimental results for only one D-shape spar could be determined, however, and agreed within 13.8 percent of the analytical results. Frequencies corresponding to the five global modes for the three square spars agreed within 9.5, 11.6, and 8.5 percent of the respective analytical results and for the three elliptical spars agreed within 4.9, 7.7, and 9.6 percent of the respective analytical results.
Lethal head entrapment--a problem characteristic of early childhood.
Byard, Roger W; Charlwood, Cheryl
2009-08-01
Accidental deaths in infancy and early childhood often result from young childrens' lack of understanding of the dangers of certain situations and their physical inability to extricate themselves from potentially lethal circumstances. Two cases are reported to demonstrate an age-related susceptibility in the young to lethal head entrapment. Case 1: a 5-month-old girl smothered when she slipped down in her stroller, trapping her head beneath the frame and forcing her face into the soft material of the base. Case 2: a 14-month-old boy was hanged while exploring a filing cabinet when his head became caught between two lower drawers. Additional mental and physical characteristics that predispose young children and infants to lethal head entrapment include an inability to effectively problem solve once confronted with a hazardous situation, and relatively large heads and weak neck musculature. Because of these features lethal head entrapment represents a particular circumstance that may predispose to accidental asphyxial deaths in the very young. A combination of careful death scene and autopsy evaluations will be required to confirm the alleged circumstances of death in these cases, including mortuary re-enactments and assessment of the deceased infant's level of physical maturity and mobility. PMID:19573845
NASA Astrophysics Data System (ADS)
Dalla Riva, M.; Musolino, P.
2014-01-01
We consider a periodically perforated domain obtained by making in R^n a periodic set of holes, each of them of size proportional to \\epsilon. Then we introduce a nonlinear boundary value problem for the Lam\\'e equations in such a periodically perforated domain. The unknown of the problem is a vector valued function u which represents the displacement attained in the equilibrium configuration by the points of a periodic linearly elastic matrix with a hole of size \\epsilon contained in each periodic cell. We assume that the traction exerted by the matrix on the boundary of each hole depends (nonlinearly) on the displacement attained by the points of the boundary of the hole. Then our aim is to describe what happens to the displacement vector function u when \\epsilon tends to 0. Under suitable assumptions we prove the existence of a family of solutions {u(\\epsilon,.) : \\epsilon \\in ]0,\\epsilon'[} with a prescribed limiting behaviour when \\epsilon approaches 0. Moreover, the family {u(\\epsilon,.) : \\epsilon \\in ]0,\\epsilon'[} is in a sense locally unique and can be continued real analytically for negative values of \\epsilon.
NASA Technical Reports Server (NTRS)
Lara, Martin; Palacian, Jesus F.
2007-01-01
Frozen orbits of the Hill problem are determined in the double averaged problem, where short and long period terms are removed by means of Lie transforms. The computation of initial conditions of corresponding quasi periodic solutions in the non-averaged problem is straightforward for the perturbation method used provides the explicit equations of the transformation that connects the averaged and non-averaged models. A fourth order analytical theory reveals necessary for the accurate computation of quasi periodic, frozen orbits.
Hard Data Analytics Problems Make for Better Data Analysis Algorithms: Bioinformatics as an Example
Widera, Paweł; Lazzarini, Nicola; Krasnogor, Natalio
2014-01-01
Abstract Data mining and knowledge discovery techniques have greatly progressed in the last decade. They are now able to handle larger and larger datasets, process heterogeneous information, integrate complex metadata, and extract and visualize new knowledge. Often these advances were driven by new challenges arising from real-world domains, with biology and biotechnology a prime source of diverse and hard (e.g., high volume, high throughput, high variety, and high noise) data analytics problems. The aim of this article is to show the broad spectrum of data mining tasks and challenges present in biological data, and how these challenges have driven us over the years to design new data mining and knowledge discovery procedures for biodata. This is illustrated with the help of two kinds of case studies. The first kind is focused on the field of protein structure prediction, where we have contributed in several areas: by designing, through regression, functions that can distinguish between good and bad models of a protein's predicted structure; by creating new measures to characterize aspects of a protein's structure associated with individual positions in a protein's sequence, measures containing information that might be useful for protein structure prediction; and by creating accurate estimators of these structural aspects. The second kind of case study is focused on omics data analytics, a class of biological data characterized for having extremely high dimensionalities. Our methods were able not only to generate very accurate classification models, but also to discover new biological knowledge that was later ratified by experimentalists. Finally, we describe several strategies to tightly integrate knowledge extraction and data mining in order to create a new class of biodata mining algorithms that can natively embrace the complexity of biological data, efficiently generate accurate information in the form of classification/regression models, and extract valuable
NASA Astrophysics Data System (ADS)
de Saedeleer, Bernard
2005-03-01
This paper is a contribution to the Theory of the Artificial Satellite, within the frame of the Lie Transform as canonical perturbation technique (elimination of the short period terms). We consider the perturbation by any zonal harmonic J n (n ≥ 2) of the primary on the satellite, what we call here the complete zonal problem of the artificial satellite. This is quite useful for primaries with symmetry of revolution. We give an analytical formula to compute directly the first order averaged Hamiltonian. The computation is carried out in closed form for all terms, avoiding therefore tedious expansions in the eccentricity or in any anomaly; this feature makes the averaging process, not only valid for all kind of elliptic trajectories but at the same time it yields the averaged Hamiltonian in a very short and compact way. The formula allows us to now skip the averaging process, which means an asymptotic gain of a factor 3n/2 regarding the computational cost of the n th zonal. Our analytical formulae have been widely checked, by comparison on one hand with published works (Brouwer, 1959) (which contained results for particular zonal harmonics, let’s say typically from J 2 to J 8), and on the other hand with the results of 3 symbolic manipulation software, among which the MM (standing for ‘Moon’s series Manipulator’), which has already been used and described in (De Saedeleer B., 2004). Additionally, the first order generator associated with this transformation is given into the same closed form, and has also been validated.
Critical Task Characteristics in Problem-Based Learning
ERIC Educational Resources Information Center
Otting, Hans; Zwaal, Wichard
2006-01-01
Tasks and problems in problem-based learning (PBL) are supposed to trigger and structure the learning process. The quality of problems in PBL is generally regarded as an important driver of the individual and collaborative learning processes. Although the importance of the PBL task is widely recognized, there is a lack of empirical findings and…
NASA Astrophysics Data System (ADS)
Yang, D. G.; Choi, Y. H.; Kim, Y. G.; Song, J. B.; Lee, H. G.
2016-03-01
This paper presents results, experimental and analytical, of the electrical characteristics of GdBCO single-pancake coils co-wound with a brass tape as metallic insulation (MI coil). The GdBCO pancakes were subjected to sudden discharge, charge-discharge, and over-current tests. The sudden discharge and charge-discharge test results of the MI coil demonstrated that MI coils can be charged and discharged significantly faster than non-insulated coils that are wound only with GdBCO tape. In over-current tests at 150 A (1.25Ic), the MI coil exhibited better electrical behavior, i.e., self-protecting features, than its counterpart co-wound with Kapton tape, an insulator. Moreover, the experimental and analytical results are in agreement, validating the use of a concise equivalent parallel-RL circuit model for the MI coil to characterize its electrical behavior. Overall, the MI winding technique is highly promising to help build compact, mechanically robust, and self-protecting magnets composed of REBCO pancake coils. With no organic material in the winding, MI REBCO pancakes will be immune to neutron radiation damage, making the MI winding technique a viable option for fusion reactors, such as for toroidal field, poroidal field magnets, and central solenoid.
Yang, D G; Choi, Y H; Kim, Y G; Song, J B; Lee, H G
2016-03-01
This paper presents results, experimental and analytical, of the electrical characteristics of GdBCO single-pancake coils co-wound with a brass tape as metallic insulation (MI coil). The GdBCO pancakes were subjected to sudden discharge, charge-discharge, and over-current tests. The sudden discharge and charge-discharge test results of the MI coil demonstrated that MI coils can be charged and discharged significantly faster than non-insulated coils that are wound only with GdBCO tape. In over-current tests at 150 A (1.25I(c)), the MI coil exhibited better electrical behavior, i.e., self-protecting features, than its counterpart co-wound with Kapton tape, an insulator. Moreover, the experimental and analytical results are in agreement, validating the use of a concise equivalent parallel-RL circuit model for the MI coil to characterize its electrical behavior. Overall, the MI winding technique is highly promising to help build compact, mechanically robust, and self-protecting magnets composed of REBCO pancake coils. With no organic material in the winding, MI REBCO pancakes will be immune to neutron radiation damage, making the MI winding technique a viable option for fusion reactors, such as for toroidal field, poroidal field magnets, and central solenoid. PMID:27036797
Applied Analytical Methods for Solving Some Problems of Wave Propagation in the Coastal Areas
NASA Astrophysics Data System (ADS)
Gagoshidze, Shalva; Kodua, Manoni
2016-04-01
Analytical methods, easy for application, are proposed for the solution of the following four classical problems of coastline hydro mechanics: 1. Refraction of waves on coast slopes of arbitrary steepness; 2. Wave propagation in tapering water areas; 3. Longitudinal waves in open channels; 4. Long waves on uniform and non-uniform flows of water. The first three of these problems are solved by the direct Galerkin-Kantorovich method with a choice , of basic functions which completely satisfy all boundary conditions. This approach leads to obtaining new evolutionary equations which can be asymptotically solved by the WKB method. The WKB solution of the first problem enables us to easily determine the three-dimensional field of velocities and to construct the refraction picture of the wave surface near the coast having an arbitrary angle of slope to the horizon varying from 0° to 180°. This solution, in particular for a vertical cliff, fully agrees with Stoker's particular but difficult solution. Moreover, it is shown for the first time that our Schrödinger type evolutionary equation leads to the formation of the so-called "potential wells" if the angle of coast slope to the horizon exceeds 45°, while the angle given at infinity (i.e. at a large distance from the shore) between the wave crests and the coastline exceeds 75°. This theoretical result expressed in terms of elementary functions is well consistent with the experimental observations and with lot of aerial photographs of waves in the coastal zones of the oceans [1,2]. For the second problem we introduce the notions of "wide" and "narrow" water areas. It is shown that Green's law on the wave height growth holds only for the narrow part of the water area, whereas in the wide part the tapering of the water area leads to an insignificant decrease of the wave height. For the third problem, the bank slopes of trapezoidal channels are assumed to have an arbitrary angle of steepness. So far we have known the
ERIC Educational Resources Information Center
Thorsland, Martin N.; Novak, Joseph D.
1974-01-01
Described is an approach to assessment of intuitive and analytic modes of thinking in physics. These modes of thinking are associated with Ausubel's theory of learning. High ability in either intuitive or analytic thinking was associated with success in college physics, with high learning efficiency following a pattern expected on the basis of…
NASA Astrophysics Data System (ADS)
Moench, Allen F.
2008-06-01
A 7-d, constant rate aquifer test conducted by University of Waterloo researchers at Canadian Forces Base Borden in Ontario, Canada, is useful for advancing understanding of fluid flow processes in response to pumping from an unconfined aquifer. Measured data include not only drawdown in the saturated zone but also volumetric soil moisture measured at various times and distances from the pumped well. Analytical analyses were conducted with the model published in 2001 by Moench and colleagues, which allows for gradual drainage but does not include unsaturated zone characteristics, and the model published in 2006 by Mathias and Butler, which assumes that moisture retention and relative hydraulic conductivity (RHC) in the unsaturated zone are exponential functions of pressure head. Parameters estimated with either model yield good matches between measured and simulated drawdowns in piezometers. Numerical analyses were conducted with two versions of VS2DT: one that uses traditional Brooks and Corey functional relations and one that uses a RHC function introduced in 2001 by Assouline that includes an additional parameter that accounts for soil structure and texture. The analytical model of Mathias and Butler and numerical model of VS2DT with the Assouline model both show that the RHC function must contain a fitting parameter that is different from that used in the moisture retention function. Results show the influence of field-scale heterogeneity and suggest that the RHC at the Borden site declines more rapidly with elevation above the top of the capillary fringe than would be expected if the parameters were to reflect local- or core-scale soil structure and texture.
Moench, A.F.
2008-01-01
A 7-d, constant rate aquifer test conducted by University of Waterloo researchers at Canadian Forces Base Borden in Ontario, Canada, is useful for advancing understanding of fluid flow processes in response to pumping from an unconfined aquifer. Measured data include not only drawdown in the saturated zone but also volumetric soil moisture measured at various times and distances from the pumped well. Analytical analyses were conducted with the model published in 2001 by Moench and colleagues, which allows for gradual drainage but does not include unsaturated zone characteristics, and the model published in 2006 by Mathias and Butler, which assumes that moisture retention and relative hydraulic conductivity (RHC) in the unsaturated zone are exponential functions of pressure head. Parameters estimated with either model yield good matches between measured and simulated drawdowns in piezometers. Numerical analyses were conducted with two versions of VS2DT: one that uses traditional Brooks and Corey functional relations and one that uses a RHC function introduced in 2001 by Assouline that includes an additional parameter that accounts for soil structure and texture. The analytical model of Mathias and Butler and numerical model of VS2DT with the Assouline model both show that the RHC function must contain a fitting parameter that is different from that used in the moisture retention function. Results show the influence of field-scale heterogeneity and suggest that the RHC at the Borden site declines more rapidly with elevation above the top of the capillary fringe than would be expected if the parameters were to reflect local- or core-scale soil structure and texture.
A measurement-based analytical approach to the bioluminescence tomography problem
NASA Astrophysics Data System (ADS)
Erkol, Hakan; Demirkiran, Aytac; Kipergil, Esra-Aytac; Uluc, Nasire; Unlu, Mehmet B.
2014-03-01
This work presents an analytical approach for the solution of the tissue diffusion equation based on the bound- ary measurements. We consider a bioluminescent point source in both homogeneous and heterogeneous circular turbid media. The point source is described by the Dirac delta function. Analytical expressions for the strength and position of the point source are obtained introducing boundary measurements and then applying appropriate boundary conditions. In addition, numerical simulations are performed for the position of the source. Calculations show that that the analytical results are in a good accordance with the numerical results.
NASA Astrophysics Data System (ADS)
Arnab, Salman M.; Kabir, M. Z.
2014-01-01
An analytical model for analyzing the current-voltage (J-V) characteristics of bulk heterojunction (BHJ) organic solar cells is developed by incorporating exponential photon absorption, dissociation efficiency of bound electron-hole pairs (EHPs), carrier trapping, and carrier drift and diffusion in the photon absorption layer. Modified Braun's model is used to compute the electric field-dependent dissociation efficiency of the bound EHPs. The charge carrier concentrations and hence the photocurrent are calculated by solving the carrier continuity equation for both holes and electrons in the organic layer. The overall load current is calculated considering the actual solar spectrum and voltage dependent forward dark current. The model is verified by published experimental results. The efficiency of the P3HT:PCBM based solar cells critically depends on the dissociation of bound EHPs. On the other hand, cells made of a blend of the conjugated polymer (PCDTBT) with the soluble fullerene derivative (PCBM) show nearly unity dissociation efficiency, and their cell efficiency strongly depends on the charge collection efficiency. The effects of carrier lifetimes on the performance of PCDTBT solar cells have also been studied. The model is also used to investigate the effect of titanium oxide (TiOx) layer (at the back contact) on the J-V characteristics of PCDTBT solar cells. The results of this paper indicate that improvement of charge carrier transport in PCDTBT:PCBM blend and dissociation of bound EHPs in P3HT:PCBM blend are extremely important to increase the power conversion efficiency of the respective BHJ solar cells.
Arnab, Salman M.; Kabir, M. Z.
2014-01-21
An analytical model for analyzing the current-voltage (J-V) characteristics of bulk heterojunction (BHJ) organic solar cells is developed by incorporating exponential photon absorption, dissociation efficiency of bound electron-hole pairs (EHPs), carrier trapping, and carrier drift and diffusion in the photon absorption layer. Modified Braun's model is used to compute the electric field-dependent dissociation efficiency of the bound EHPs. The charge carrier concentrations and hence the photocurrent are calculated by solving the carrier continuity equation for both holes and electrons in the organic layer. The overall load current is calculated considering the actual solar spectrum and voltage dependent forward dark current. The model is verified by published experimental results. The efficiency of the P3HT:PCBM based solar cells critically depends on the dissociation of bound EHPs. On the other hand, cells made of a blend of the conjugated polymer (PCDTBT) with the soluble fullerene derivative (PCBM) show nearly unity dissociation efficiency, and their cell efficiency strongly depends on the charge collection efficiency. The effects of carrier lifetimes on the performance of PCDTBT solar cells have also been studied. The model is also used to investigate the effect of titanium oxide (TiO{sub x}) layer (at the back contact) on the J-V characteristics of PCDTBT solar cells. The results of this paper indicate that improvement of charge carrier transport in PCDTBT:PCBM blend and dissociation of bound EHPs in P3HT:PCBM blend are extremely important to increase the power conversion efficiency of the respective BHJ solar cells.
O'Rourke, Joanne McFarland; Roehrig, Stephen; Heeringa, Steven G; Reed, Beth Glover; Birdsall, William C; Overcashier, Margaret; Zidar, Kelly
2006-09-01
MEASURES USED TO PROTECT SUBJECTS in publicly distributed microdata files often have a significant negative impact on key analytic uses of the data. For example, it may be important to analyze subpopulations within a data file such as racial minorities, yet these subjects may present the greatest disclosure risk because their records tend to stand out or be unique. Files or records that are linkable create another type of disclosure risk-common elements between two files can be used to link files with sensitive data to externally available files that disclose identity. Examples of disclosure limitation methods used to address these types of issues include blanking out data, coarsening response categories, or withholding data altogether. However, the very detail that creates the greatest risk also provides insight into differences that are of greatest interest to analysts. Restricted-use agreements that provide unaltered versions of the data may not be available, or only selectively so. The public-use version of the data is very important because it is likely to be the only one to which most researchers, policy analysts, teaching faculty, and students will ever have access. Hence, it is the version from which much of the utility of the data is extracted and often it effectively becomes the historical record of the data collection. This underscores the importance that the disclosure review c ommittee s trikes a g ood b alance b etween protection and u tility. In this paper we d escrib e our disclosure review committee's (DRC) analysis and resulting data protection plans for two national studies and one administrative data system. Three distinct disclosure limitation methods were employed, taking key uses of the data into consideration, to protect respondents while still providing statistically accurate and highly useful public-use data. The techniques include data swapping, microaggregation, and suppression of detailed geographic data. We describe the characteristics
Analytic Solution to the Problem of Aircraft Electric Field Mill Calibration
NASA Technical Reports Server (NTRS)
Koshak, William
2003-01-01
It is by no means a simple task to retrieve storm electric fields from an aircraft instrumented with electric field mill sensors. The presence of the aircraft distorts the ambient field in a complicated way. Before retrievals of the storm field can be made, the field mill measurement system must be "calibrated". In other words, a relationship between impressed (i.e., ambient) electric field and mill output must be established. If this relationship can be determined, it is mathematically inverted so that ambient field can be inferred from the mill outputs. Previous studies have primarily focused on linear theories where the relationship between ambient field and mill output is described by a "calibration matrix" M. Each element of the matrix describes how a particular component of the ambient field is enhanced by the aircraft. For example the product M(sub ix), E(sub x), is the contribution of the E(sub x) field to the i(th) mill output. Similarly, net aircraft charge (described by a "charge field component" E(sub q)) contributes an amount M(sub iq)E(sub q) to the output of the i(th) sensor. The central difficulty in obtaining M stems from the fact that the impressed field (E(sub x), E(sub y), E(sub z), E(sub q) is not known but is instead estimated. Typically, the aircraft is flown through a series of roll and pitch maneuvers in fair weather, and the values of the fair weather field and aircraft charge are estimated at each point along the aircraft trajectory. These initial estimates are often highly inadequate, but several investigators have improved the estimates by implementing various (ad hoc) iterative methods. Unfortunately, none of the iterative methods guarantee absolute convergence to correct values (i.e., absolute convergence to correct values has not been rigorously proven). In this work, the mathematical problem is solved directly by analytic means. For m mills installed on an arbitrary aircraft, it is shown that it is possible to solve for a single 2m
Some Problems of Rocket-Space Vehicles' Characteristics co- ordination
NASA Astrophysics Data System (ADS)
Sergienko, Alexander A.
2002-01-01
of the XX century suffered a reverse. The designers of the United States' firms and enterprises of aviation and rocket-space industry (Boeing, Rocketdyne, Lockheed Martin, McDonnell Douglas, Rockwell, etc.) and NASA (Marshall Space Flight Center, Johnson Space Center, Langley Research Center and Lewis Research Center and others) could not correctly co-ordinate the characteristics of a propulsion system and a space vehicle for elaboration of the "Single-Stage-To-Orbit" reusable vehicle (SSTO) as an integral whole system, which is would able to inject a payload into an orbit and to return back on the Earth. jet nozzle design as well as the choice of propulsion system characteristics, ensuring the high ballistic efficiency, are considered in the present report. The efficiency criterions for the engine and launch system parameters optimization are discussed. The new methods of the nozzle block optimal parameters' choice for the satisfaction of the object task of flight are suggested. The family of SSTO with a payload mass from 5 to 20 ton and initial weight under 800 ton is considered.
NASA Technical Reports Server (NTRS)
Gossard, Myron L
1952-01-01
An iterative transformation procedure suggested by H. Wielandt for numerical solution of flutter and similar characteristic-value problems is presented. Application of this procedure to ordinary natural-vibration problems and to flutter problems is shown by numerical examples. Comparisons of computed results with experimental values and with results obtained by other methods of analysis are made.
Problems with the differential receiver operating characteristic (DROC) method
NASA Astrophysics Data System (ADS)
Chakraborty, Dev P.
2004-05-01
Most papers in these proceedings present ideas that work. This is the story of an idea that did not work as intended. The differential receiver operating characteristic (DROC) method was proposed about 8 years ago. It was intended to measure the difference in performance between two imaging modalities. It was expected that the DROC method could outperform the ROC method in statistical power. This expectation has not been borne out and the author no longer recommends the DROC method. The purpose of this paper is to present a critical look at this method, why the author initially believed it should work, the assumptions involved and the fallacies. The author believes there is value to this frank account as it has yielded, at least for the author, new insights into ROC analysis. The author concludes with a few personal reflections on his experience with this project and advice on how to deal with negative results.
Filho, J. F. P.
2013-07-01
In this work, an analytical discrete ordinates method is used to solve a nodal formulation of a neutron transport problem in x, y-geometry. The proposed approach leads to an important reduction in the order of the associated eigenvalue systems, when combined with the classical level symmetric quadrature scheme. Auxiliary equations are proposed, as usually required for nodal methods, to express the unknown fluxes at the boundary introduced as additional unknowns in the integrated equations. Numerical results, for the problem defined by a two-dimensional region with a spatially constant and isotropically emitting source, are presented and compared with those available in the literature. (authors)
How Big of a Problem is Analytic Error in Secondary Analyses of Survey Data?
West, Brady T.; Sakshaug, Joseph W.; Aurelien, Guy Alain S.
2016-01-01
Secondary analyses of survey data collected from large probability samples of persons or establishments further scientific progress in many fields. The complex design features of these samples improve data collection efficiency, but also require analysts to account for these features when conducting analysis. Unfortunately, many secondary analysts from fields outside of statistics, biostatistics, and survey methodology do not have adequate training in this area, and as a result may apply incorrect statistical methods when analyzing these survey data sets. This in turn could lead to the publication of incorrect inferences based on the survey data that effectively negate the resources dedicated to these surveys. In this article, we build on the results of a preliminary meta-analysis of 100 peer-reviewed journal articles presenting analyses of data from a variety of national health surveys, which suggested that analytic errors may be extremely prevalent in these types of investigations. We first perform a meta-analysis of a stratified random sample of 145 additional research products analyzing survey data from the Scientists and Engineers Statistical Data System (SESTAT), which describes features of the U.S. Science and Engineering workforce, and examine trends in the prevalence of analytic error across the decades used to stratify the sample. We once again find that analytic errors appear to be quite prevalent in these studies. Next, we present several example analyses of real SESTAT data, and demonstrate that a failure to perform these analyses correctly can result in substantially biased estimates with standard errors that do not adequately reflect complex sample design features. Collectively, the results of this investigation suggest that reviewers of this type of research need to pay much closer attention to the analytic methods employed by researchers attempting to publish or present secondary analyses of survey data. PMID:27355817
ERIC Educational Resources Information Center
Thorsland, Martin N.; Novak, Joseph D.
A study on individual differences in problem solving approach and their relationships to various learning-related parameters was conducted with a random sample of 25 subjects enrolled in an introductory physics course utilizing instruction through audio-tutorial methods. The subjects received interviews consisting of four problems in energy…
Analytical Problems and Suggestions in the Analysis of Behavioral Economic Demand Curves.
Yu, Jihnhee; Liu, Liu; Collins, R Lorraine; Vincent, Paula C; Epstein, Leonard H
2014-01-01
Behavioral economic demand curves (Hursh, Raslear, Shurtleff, Bauman, & Simmons, 1988) are innovative approaches to characterize the relationships between consumption of a substance and its price. In this article, we investigate common analytical issues in the use of behavioral economic demand curves, which can cause inconsistent interpretations of demand curves, and then we provide methodological suggestions to address those analytical issues. We first demonstrate that log transformation with different added values for handling zeros changes model parameter estimates dramatically. Second, demand curves are often analyzed using an overparameterized model that results in an inefficient use of the available data and a lack of assessment of the variability among individuals. To address these issues, we apply a nonlinear mixed effects model based on multivariate error structures that has not been used previously to analyze behavioral economic demand curves in the literature. We also propose analytical formulas for the relevant standard errors of derived values such as P max, O max, and elasticity. The proposed model stabilizes the derived values regardless of using different added increments and provides substantially smaller standard errors. We illustrate the data analysis procedure using data from a relative reinforcement efficacy study of simulated marijuana purchasing. PMID:26741176
Zatsiorsky, Vladimir M.
2011-01-01
One of the key problems of motor control is the redundancy problem, in particular how the central nervous system (CNS) chooses an action out of infinitely many possible. A promising way to address this question is to assume that the choice is made based on optimization of a certain cost function. A number of cost functions have been proposed in the literature to explain performance in different motor tasks: from force sharing in grasping to path planning in walking. However, the problem of uniqueness of the cost function(s) was not addressed until recently. In this article, we analyze two methods of finding additive cost functions in inverse optimization problems with linear constraints, so-called linear-additive inverse optimization problems. These methods are based on the Uniqueness Theorem for inverse optimization problems that we proved recently (Terekhov et al., J Math Biol 61(3):423–453, 2010). Using synthetic data, we show that both methods allow for determining the cost function. We analyze the influence of noise on the both methods. Finally, we show how a violation of the conditions of the Uniqueness Theorem may lead to incorrect solutions of the inverse optimization problem. PMID:21311907
Terekhov, Alexander V; Zatsiorsky, Vladimir M
2011-02-01
One of the key problems of motor control is the redundancy problem, in particular how the central nervous system (CNS) chooses an action out of infinitely many possible. A promising way to address this question is to assume that the choice is made based on optimization of a certain cost function. A number of cost functions have been proposed in the literature to explain performance in different motor tasks: from force sharing in grasping to path planning in walking. However, the problem of uniqueness of the cost function(s) was not addressed until recently. In this article, we analyze two methods of finding additive cost functions in inverse optimization problems with linear constraints, so-called linear-additive inverse optimization problems. These methods are based on the Uniqueness Theorem for inverse optimization problems that we proved recently (Terekhov et al., J Math Biol 61(3):423-453, 2010). Using synthetic data, we show that both methods allow for determining the cost function. We analyze the influence of noise on the both methods. Finally, we show how a violation of the conditions of the Uniqueness Theorem may lead to incorrect solutions of the inverse optimization problem. PMID:21311907
A meta-analytic study of self-help interventions for anxiety problems.
Hirai, Michiyo; Clum, George A
2006-06-01
The present study examined the effectiveness of self-help (SH) interventions for individuals with anxiety problems. Thirty-three studies, targeting a variety of anxiety disorders and problems, met criteria for inclusion with 1,582 clinical and subclinical participants. Self-help formats included books, audio/videotapes, and computer/Internet-based programs. The average effect sizes (Cohen's ds) comparing SH interventions to control groups for target symptoms were .62 at posttreatment and .51 at follow-up. When compared to therapist-directed interventions (TDIs), the average effect sizes (Cohen's ds) for target problems were -.42 at posttreatment and -.36 at follow-up. Format of SH materials, type of target disorder, presence of minimal therapist contact, and other study parameters were examined for their effect on treatment outcome. The results were discussed from the perspective of a stepped-care approach for anxiety problems. PMID:16942965
A noncanonical analytic solution to the J2 perturbed two-body problem
NASA Technical Reports Server (NTRS)
Jezewski, D. J.
1983-01-01
The motion of a satellite subject to an inverse-square gravitational force of attraction and a perturbation due to the earth's oblateness as the J2 term is analyzed, and a uniform, analytic solution correct to first-order in J2, is obtained using a noncanonical approach. The basis for the solution is the transformation and uncoupling of the differential equations for the model. The resulting solution is expressed in terms of elementary functions of the independent variable (the 'true anomaly'), and is of a compact and simple form. Numerical results are comparable to existing solutions.
Zimmerman, R.W.; Bodvarsson, G.S.
1990-01-01
Various analytical and numerical approaches are presented for the study of unsaturated flow processes in the vicinity of the Yucca Mountain, Nevada, the proposed site of an underground radioactive waste repository. Approximate analytical methods are used to study absorption of water from a saturated fracture into the adjacent rock. These solutions are incorporated into a numerical simulator as fracture/matrix interaction terms to treat problems such as flow along a fracture with transverse leakage into the matrix. An automatic fracture/matrix mesh generator is described; it allows for more efficient mesh generation for fractured/porous media, and consequently leads to large savings in computational time and cost. 21 refs., 6 figs.
Gray, D.B.; McMechan, G.A.
1995-06-01
The analytic solution of the Lippman-Schwinger seismic inverse problem in three spatial dimensions, assuming a point source and a constant-density earth model, is valid in the spatial zero frequency limit. It is expressed as a two-dimensional inverse Fourier transform followed by an inverse Laplace transform. For the case of laterally homogeneous velocity, the analytic solution is correct when applied to a forward solution of the wave equation for a single-interface velocity model. Error surfaces of the non-linear, iterative, least-squares inversions corresponding to multiple, constant-velocity, horizontal layers have an absolute minimum at or near the location of the solution parameters for zero and low frequencies. The error surface for a scattered wavefield dataset generated by 3D finite-difference modeling combined with a priori constraints, produces nearly correct solutions for a range of low frequencies. Thus, this approach has potential for applicability to field data. 24 refs., 7 figs.
An analytical solution for the magneto-electro-elastic bimorph beam forced vibrations problem
NASA Astrophysics Data System (ADS)
Milazzo, A.; Orlando, C.; Alaimo, A.
2009-08-01
Based on the Timoshenko beam theory and on the assumption that the electric and magnetic fields can be treated as steady, since elastic waves propagate very slowly with respect to electromagnetic ones, a general analytical solution for the transient analysis of a magneto-electro-elastic bimorph beam is obtained. General magneto-electric boundary conditions can be applied on the top and bottom surfaces of the beam, allowing us to study the response of the bilayer structure to electromagnetic stimuli. The model reveals that the magneto-electric loads enter the solution as an equivalent external bending moment per unit length and as time-dependent mechanical boundary conditions through the definition of the bending moment. Moreover, the influences of the electro-mechanic, magneto-mechanic and electromagnetic coupling on the stiffness of the bimorph stem from the computation of the beam equivalent stiffness constants. Free and forced vibration analyses of both multiphase and laminated magneto-electro-elastic composite beams are carried out to check the effectiveness and reliability of the proposed analytic solution.
Analytic Challenges Arising from the STOP CRC Trial: Pragmatic Solutions for Pragmatic Problems
Vollmer, William M.; Green, Beverly B.; Coronado, Gloria D.
2015-01-01
Context: Pragmatic trials lack the relatively tight quality control of traditional efficacy studies and hence may pose added analytic challenges owing to the practical realities faced in carrying them out. Case Description: STOP CRC is a cluster randomized trial testing the effectiveness of automated, electronic medical record (EMR)-driven strategies to raise colorectal cancer (CRC) screening rates in safety net clinics. Screen-eligible participants were accrued during year 1 and followed for 12 months (measurement window) to assess completion of a fecal screening test. Control clinics implemented the intervention in year 2. Implementation Challenges/Analytic Issues: Due to limitations on how we could build the intervention tools, the overlap of the year 1 measurement windows with year 2 intervention rollout posed a potential for contamination of the primary outcome for control participants. In addition, a variety of factors led to a lack of synchronization of the measurement windows with actual intervention delivery. In both cases, the net impact of these factors would be to diminish the estimated impact of the intervention. Proposed Solutions: We dealt with the overlap issue by delaying the start of intervention rollout to control clinics in year 2 by 6 months and by truncating the measurement windows for intervention and control participants at this point. In addition we formulated three sensitivity analyses to help address the issue of asynchronization. Conclusion: This case study might help other investigators facing similar challenges think about such issues and the pros and cons of various strategies for dealing with them. PMID:26793738
Peer and Parenting Characteristics of Boys and Girls with Subclinical Attention Problems
ERIC Educational Resources Information Center
Rielly, Nicole E.; Craig, Wendy M.; Parker, Kevin C. H.
2006-01-01
Objective: This study examines peer and parenting characteristics of 149 boys and girls with and without subclinical attention problems. Method: Multivariate analyses showed that children with attention problems had higher levels of negative peer nominations and conflict and betrayal in friendships, and their parents tended to use higher levels of…
Fast Single Image Super-Resolution Using a New Analytical Solution for l2 - l2 Problems.
Zhao, Ningning; Wei, Qi; Basarab, Adrian; Dobigeon, Nicolas; Kouame, Denis; Tourneret, Jean-Yves
2016-08-01
This paper addresses the problem of single image super-resolution (SR), which consists of recovering a high-resolution image from its blurred, decimated, and noisy version. The existing algorithms for single image SR use different strategies to handle the decimation and blurring operators. In addition to the traditional first-order gradient methods, recent techniques investigate splitting-based methods dividing the SR problem into up-sampling and deconvolution steps that can be easily solved. Instead of following this splitting strategy, we propose to deal with the decimation and blurring operators simultaneously by taking advantage of their particular properties in the frequency domain, leading to a new fast SR approach. Specifically, an analytical solution is derived and implemented efficiently for the Gaussian prior or any other regularization that can be formulated into an l2 -regularized quadratic model, i.e., an l2 - l2 optimization problem. The flexibility of the proposed SR scheme is shown through the use of various priors/regularizations, ranging from generic image priors to learning-based approaches. In the case of non-Gaussian priors, we show how the analytical solution derived from the Gaussian case can be embedded into traditional splitting frameworks, allowing the computation cost of existing algorithms to be decreased significantly. Simulation results conducted on several images with different priors illustrate the effectiveness of our fast SR approach compared with existing techniques. PMID:27187960
NASA Astrophysics Data System (ADS)
Zhao, Y. H.; Li, W. M.; Chin, J. S.
1986-06-01
The variation of spray characteristics (Sauter Mean Diameter and Rosin-Rammler drop-size distribution parameter) downstream of a pressure swirl atomizer along radial distance has been measured by laser light scattering technology. An analytical model has been developed that is capable of predicting the variation of spray characteristics along radial distance. A comparison between the prediction and experimental data shows excellent agreement. It shows that the spray model proposed, although relatively simple, is correct and can be used with some expansion and modification to predict more complicated spray systems.
NASA Technical Reports Server (NTRS)
Carden, H. D.
1974-01-01
Experimental and analytical natural frequencies, nodal patterns, and typical modal displacements for a corrugated, flexibly supported, heat-shield panel are discussed. Good correlation was found between the experimental data and NASTRAN analytical results for the corrugated panel over a relatively wide frequency spectrum covered in the investigation. Of the two experimental techniques used for mode shape and displacement measurements (a noncontacting displacement sensor system and a holographic technique using a helium-neon, continuous-wave laser), the holographic technique was found, in the present investigation, to be faster and better suited for determining a large number of complex nodal patterns of the corrugated panel.
Exact analytical solution to a transient conjugate heat-transfer problem
NASA Technical Reports Server (NTRS)
Sucec, J.
1973-01-01
An exact analytical solution is found for laminar, constant-property, slug flow over a thin plate which is also convectively cooled from below. The solution is found by means of two successive Laplace transformations when a transient in the plate and the fluid is initiated by a step change in the fluid inlet temperature. The exact solution yields the transient fluid temperature, surface heat flux, and surface temperature distributions. The results of the exact transient solution for the surface heat flux are compared to the quasi-steady values, and a criterion for the validity of the quasi-steady results is found. Also the effect of the plate coupling parameter on the surface heat flux are investigated.
ERIC Educational Resources Information Center
van Rooij, Iris; Schactman, Alissa; Kadlec, Helena; Stege, Ulrike
2006-01-01
The Euclidean Traveling Salesperson Problem (E-TSP) is a useful task to study how humans optimize when faced with computational intractability. It has been found that humans are capable of finding high-quality solutions for E-TSP in a relatively short time and with seemingly little cognitive effort. This observation has led to two general…
Educational Reform as a Dynamic System of Problems and Solutions: Towards an Analytic Instrument
ERIC Educational Resources Information Center
Luttenberg, Johan; Carpay, Thérèse; Veugelers, Wiel
2013-01-01
Large-scale educational reforms are difficult to realize and often fail. In the literature, the course of reform and problems associated with this are frequently discussed. The explanations and recommendations then provided are so diverse that it is difficult to gain a comprehensive overview of what factors are at play and how to take them into…
ERIC Educational Resources Information Center
Comer, Jonathan S.; Chow, Candice; Chan, Priscilla T.; Cooper-Vince, Christine; Wilson, Lianna A. S.
2013-01-01
Objective: Service use trends showing increased off-label prescribing in very young children and reduced psychotherapy use raise concerns about quality of care for early disruptive behavior problems. Meta-analysis can empirically clarify best practices and guide clinical decision making by providing a quantitative synthesis of a body of…
Transport synthetic acceleration for long-characteristics assembly-level transport problems
Zika, M.R.; Adams, M.L.
2000-02-01
The authors apply the transport synthetic acceleration (TSA) scheme to the long-characteristics spatial discretization for the two-dimensional assembly-level transport problem. This synthetic method employs a simplified transport operator as its low-order approximation. Thus, in the acceleration step, the authors take advantage of features of the long-characteristics discretization that make it particularly well suited to assembly-level transport problems. The main contribution is to address difficulties unique to the long-characteristics discretization and produce a computationally efficient acceleration scheme. The combination of the long-characteristics discretization, opposing reflecting boundary conditions (which are present in assembly-level transport problems), and TSA presents several challenges. The authors devise methods for overcoming each of them in a computationally efficient way. Since the boundary angular data exist on different grids in the high- and low-order problems, they define restriction and prolongation operations specific to the method of long characteristics to map between the two grids. They implement the conjugate gradient (CG) method in the presence of opposing reflection boundary conditions to solve the TSA low-order equations. The CG iteration may be applied only to symmetric positive definite (SPD) matrices; they prove that the long-characteristics discretization yields an SPD matrix. They present results of the acceleration scheme on a simple test problem, a typical pressurized water reactor assembly, and a typical boiling water reactor assembly.
A cluster-analytic study of substance problems and mental health among street youths.
Adlaf, E M; Zdanowicz, Y M
1999-11-01
Based on a cluster analysis of 211 street youths aged 13-24 years interviewed in 1992 in Toronto, Ontario, Canada, we describe the configuration of mental health and substance use outcomes. Eight clusters were suggested: Entrepreneurs (n = 19) were frequently involved in delinquent activity and were highly entrenched in the street lifestyle; Drifters (n = 35) had infrequent social contact, displayed lower than average family dysfunction, and were not highly entrenched in the street lifestyle; Partiers (n = 40) were distinguished by their recreational motivation for alcohol and drug use and their below average entrenchment in the street lifestyle; Retreatists (n = 32) were distinguished by their high coping motivation for substance use; Fringers (n = 48) were involved marginally in the street lifestyle and showed lower than average family dysfunction; Transcenders (n = 21), despite above average physical and sexual abuse, reported below average mental health or substance use problems; Vulnerables (n = 12) were characterized by high family dysfunction (including physical and sexual abuse), elevated mental health outcomes, and use of alcohol and other drugs motivated by coping and escapism; Sex Workers (n = 4) were highly entrenched in the street lifestyle and reported frequent commercial sexual work, above average sexual abuse, and extensive use of crack cocaine. The results showed that distress, self-esteem, psychotic thoughts, attempted suicide, alcohol problems, drug problems, dual substance problems, and dual disorders varied significantly among the eight clusters. Overall, the findings suggest the need for differential programming. The data showed that risk factors, mental health, and substance use outcomes vary among this population. Also, for some the web of mental health and substance use problems is inseparable. PMID:10548440
ERIC Educational Resources Information Center
Heckel, Robert V.; Mandell, Elizabeth
1981-01-01
A factor analytic study of the behavioral and demographic variables that describe male and female juvenile offenders in a southern correctional facility identified 10 factors for females and six for males. Items clustered much as anticipated for both groups, with family conflicts and individual neurotic traits forming clusters. (Author)
Goals and Characteristics of Long-Term Care Programs: An Analytic Model.
ERIC Educational Resources Information Center
Braun, Kathryn L.; Rose, Charles L.
1989-01-01
Used medico-social analytic model to compare five long-term care programs: Skilled Nursing Facility-Intermediate Care Facility (SNF-ICF) homes, ICF homes, foster homes, day hospitals, and home care. Identified similarities and differences among programs. Preliminary findings suggest that model is useful in the evaluation and design of long-term…
Pain beliefs and problems in functioning among people with arthritis: a meta-analytic review.
Jia, Xiaojun; Jackson, Todd
2016-10-01
In this meta-analysis, we evaluated overall strengths of relation between beliefs about pain, health, or illness and problems in functioning (i.e., functional impairment, affective distress, pain severity) in osteoarthritis and rheumatoid arthritis samples as well as moderators of these associations. In sum, 111 samples (N = 17,365 patients) met inclusion criteria. On average, highly significant, medium effect sizes were observed for associations between beliefs and problems in functioning but heterogeneity was also inflated. Effect sizes were not affected by arthritis subtype, gender, or age. However, pain belief content emerged as a significant moderator, with larger effect sizes for studies in which personal incapacity or ineffectiveness in controlling pain was a content theme of belief indices (i.e., pain catastrophizing, helplessness, self-efficacy) compared to those examining locus of control and fear/threat/harm beliefs. Furthermore, analyses of longitudinal study subsets supported the status of pain beliefs risk factors for later problems in functioning in these groups. PMID:27506911
NASA Astrophysics Data System (ADS)
Yoon, Heojeong; Woo, Ae Ja; Treagust, David; Chandrasegaran, AL
2014-01-01
The efficacy of problem-based learning (PBL) in an analytical chemistry laboratory course was studied using a programme that was designed and implemented with 20 students in a treatment group over 10 weeks. Data from 26 students in a traditional analytical chemistry laboratory course were used for comparison. Differences in the creative thinking ability of students in both the treatment and control groups were evaluated before and at the end of the implementation of the programme, using the Torrance Tests of Creative Thinking. In addition, changes in students' self-regulated learning skills using the Self-Regulated Learning Interview Schedule (SRLIS) and their self-evaluation proficiency were evaluated. Analysis of covariance showed that the creative thinking ability of the treatment group had improved statistically significantly after the PBL course (p < 0.001) compared to that of the students in the comparison group. PBL was shown to have a positive effect on creative thinking ability. The SRLIS test showed that students in the treatment group used self-regulated learning strategies more frequently than students in the comparison group. According to the results of the self-evaluation, students became more positive and confident in problem-solving and group work as the semester progressed. Overall, PBL was shown to be an effective pedagogical instructional strategy for enhancing chemistry students' creative thinking ability, self-regulated learning skills and self-evaluation.
An Analytical Singularity-Free Solution to the J2 Perturbation Problem
NASA Technical Reports Server (NTRS)
Bond, V. R.
1979-01-01
The development of a singularity-free solution of the J2 problem in satellite theory is presented. The procedure resembles that of Lyndane who rederives Brouwer's satellite theory using Poincare elements. A comparable procedure is used in this report in which the satellite theory of Scheifele, who used elements similar to the Delaunay elements but in the extended phase space, is rederived using Poincare elements also in the extended phase space. Only the short-period effects due to J2 are included.
Semi-analytical solution to the 2014 eddy current benchmark problem
NASA Astrophysics Data System (ADS)
Miorelli, Roberto; Reboud, Christophe; Voulgaraki, Charitini; Poulakis, Nikolaos; Theodoulidis, Theodoros
2015-03-01
This work proposes a solution to the 2014 eddy current testing benchmark, published by the WFNDEC and proposed by the authors. The aim of this benchmark is to provide reference data for eddy current testing configurations involving magnetic sensors -here Hall sensors- as receivers, as they present some advantages in terms of resolution and sensitivity. After a presentation of the benchmark cases, the theoretical approach used to solve the equivalent electromagnetic problem is detailed and a alternative computation of eddy current signals is proposed. Then, simulations are quantitatively compared to experimental data in each case and the results are discussed.
A general analytical solution to the geometrical problem of field matching in radiotherapy
Hernandez, V.; Arenas, M.; Pons, F.; Sempau, J.
2009-09-15
Purpose: Several authors studied the problem of geometrical matching of fields produced by medical linear accelerators. However, a general solution has yet to be published. Currently available solutions are based on parallelism arguments. This study provides a general solution, considering not only parallelism but also field sizes. Methods: A fixed field with arbitrary field size, gantry, collimator, and couch angle is considered, and another field with a fixed gantry angle is matched to it. A single reference system attached to the treatment couch is used, and two approaches are followed. In the first approach, fixed field sizes are assumed and parallelism of the adjacent field-side planes is imposed. In the second approach, fixed isocenter positions are considered and both parallelism and coincidence between field-side planes are required. Results: When fixed field sizes are assumed, rotation angles are obtained; however, the isocenters may need to be shifted to make side planes coincident and therefore achieve a proper match. When fixed isocenter positions are considered, solutions for all parameters, including the field size, are obtained and an exact geometrical match is achieved. Conclusions: General expressions to the field-matching problem are found for the two approaches followed, fixed field sizes, and fixed isocenter positions. These results can be applied to any treatment technique and can easily be implemented in modern treatment planning systems.
NASA Astrophysics Data System (ADS)
Shein, E. V.
2015-07-01
The formation, development, and some problems of the current physically based models of water and solute transfer are considered in this review. These models appeared about a half century ago. They were based on the basic laws of soil physics and other branches of soil science (laws of balance, transfer, diffusion, hydrodynamic dispersion, etc.) described by the corresponding equations and programs and supported by the experimental data in the form of physically based parameters. At present, one of the main problems in the development, adaptation, and application of these models is that the current and future mathematical models should rest upon the experimental support with a clear physical basis characterizing the nature of the phenomenon described. This experimental support enables creating research models, drawing conceptual conclusions, and, hence, understanding, analyzing, and managing soil processes. This is apparently possible only if the set of methods for the experimental support of models is substantiated, preferably in direct physical experiments and under field conditions close to the future model prognoses.
Analytic Approach to the Cloud-in-Cloud Problem for Non-Gaussian Density Fluctuations
NASA Astrophysics Data System (ADS)
Inoue, Kaiki Taro; Nagashima, Masahiro
2002-07-01
We revisit the cloud-in-cloud problem for non-Gaussian density fluctuations. We show that the extended Press-Schechter (EPS) formalism for non-Gaussian fluctuations has a flaw in describing mass functions regardless of the type of filtering. As an example, we consider non-Gaussian models in which density fluctuations at a point obey a χ2 distribution with ν degrees of freedom. We find that mass functions predicted by using an integral formula proposed by Jedamzik and Yano, Nagashima, and Gouda, properly taking into account correlation between objects at different scales, deviate from those predicted by using the EPS formalism, especially for strongly non-Gaussian fluctuations. Our results for the mass function at large mass scales are consistent with those by Avelino and Viana obtained from numerical simulations.
NASA Astrophysics Data System (ADS)
Chen, Yao; Balani, Kantesh; Agarwal, Arvind
2008-01-01
This research presents an analytical method to investigate the effect of volume fraction and the number of outer walls of multiwalled carbon nanotube (MWNT) reinforcement on load carrying capability in the aluminum oxide matrix. Interfacial shear stress transfer and energy dissipation have been estimated using the Cox model. Critical energy release rate for the debonding of MWNT from the matrix is also estimated based on the crack deflection. The computed results sufficiently manifest that MWNT pullout and crack deflection contributes greatly to improved fracture toughness of carbon nanotube reinforced aluminum oxide nanocomposites.
Language Problems Among Abused and Neglected Children: A Meta-Analytic Review.
Sylvestre, Audette; Bussières, Ève-Line; Bouchard, Caroline
2016-02-01
Research data show that exposure to abuse and neglect has detrimental effects on a child's language development. In this meta-analysis, we analyze studies (k = 23), to compare the language skills (receptive language, expressive language, pragmatics) of children who have experienced abuse and/or neglect with the language skills of children who have not experienced abuse and/or neglect and to examine whether age or type of maltreatment moderate the relationship between maltreatment and language skills. Results confirm that the language skills of children who have experienced abuse and/or neglect are delayed when compared to children who have not experienced abuse and/or neglect. Compared to older children, young children seem particularly vulnerable to abuse and neglect. No significant differences were demonstrated concerning the type of maltreatment suffered by the child. These findings support the necessity of early detection of language problems in abused and neglected children as well as early intervention in order to implement interventions that will positively stimulate their development. PMID:26620719
Razzaghi, D; Hajiesmaeilbaigi, F; Ruzbehani, M
2012-08-31
Possible effects of amplified spontaneous emission on output pulse characteristics of a Q-switched laser are discussed within the framework of a semi-analytical approach. It is shown that output energy decreases almost exponentially with average path length of the spontaneously emitted photons which in turn depends on geometrical specification and active medium properties as well as on optical finishing of the surfaces (for solid-state lasers). Optimal coupling dependence on the average path length is also investigated and shown to increase with average path length increment. (control of laser radiation parameters)
NASA Technical Reports Server (NTRS)
Rainey, A. G.; Hanson, P. W.; Martin, D. J.
1958-01-01
The static aeroelastic divergence characteristics of a delta-planform model of the canard control surface of a proposed air-to-ground missile have been studied both analytically and experimentally in the Mach number range from 0.6 to 3.0. The experiments indicated that divergence occurred at a nearly constant value of dynamic pressure at Mach numbers up to 1.2. At higher Mach numbers somewhat higher values of dynamic pressure were required to produce divergence. The analysis and the experiment indicate that the camber stiffness of the control surface and the stiffness of the control actuator are both important in divergence of surfaces of this type.
NASA Technical Reports Server (NTRS)
Purvis, C. K.; Stevens, N. J.; Oglebay, J. C.
1977-01-01
An understanding of the behavior of materials, of dielectrics in particular, under charged particle bombardment is essential to the prediction and prevention of the adverse effects of spacecraft charging. A one-dimensional model for charging of samples in a test facility was used in conjunction with experimental data taken to develop "material charging characteristics" for silvered Teflon. These characteristics were then used in a one-dimensional model for charging in space to examine expected response. Relative charging rates as well as relative charging levels for silvered Teflon and metal are discussed.
A lunar-based analytical laboratory and contamination problems in analysis of Moon and Mars samples
NASA Astrophysics Data System (ADS)
Gehrke, Charles W.
1997-07-01
A summary follows of our experiences and techniques used in the analysis of samples from Apollo Missions 11 to 17. The studies were conducted at the Ames Research Center, Moffett Field, CA, the University of Missouri, Columbia, MO, and the University of Maryland, College Park, MD, 1969 - 1974. Our search was directed to water-extractable compounds with emphasis on amino acids. Gas chromatography, ion-exchange chromatography and gas chromatography combined with mass spectrometry were used for the analysis. It is our conclusion that amino acids are not present in the lunar regolith above the background levels of our investigation (ca. 1 - 3 ng/g). The scientific debate has become heated that primitive life existed on Mars 3.6 billion years ago as reported by the NASA-Stanford team led to David McKay. Mars is destined to receive humans early in the 21st Century, preceded by many international missions to Space Station Freedom and robotic missions to the Moon and Mars. First, we must `learn to live in space'. The Moon presents a base that provides the opportunities and challenges to assemble the international interdisciplinary intellectual scientific teams and partners with many disciplines to make the next step before human exploration of Mars and the search for evidence in Martian soil and samples returned to Earth laboratories. Our experiences learned in Moon analysis will be useful in Mars exploration and returned sample study. Sensitivity at the nanogram/gram level and selectivity of analysis are highly essential. As these figures show contamination of samples is a most serious problem. However with the use of ultraclean techniques in a 100 clean room contamination can be avoided. Our speck of dust, a tiny fragment of cigarette smoke, a particle of dandruff, a droplet of saliva, all can make your results questionable. In addition, the extraction of life molecules as amino acids from the Lunar samples was a difficult process and I am sure the same difficulties
Characteristics of problem drinking in an urban South American indigenous population.
Seale, J Paul; Shellenberger, Sylvia; Sanchez, Nelia; Vogel, Robert L; Villalobos, Elibeth; Girton, Fred S; Seale, Dana M; Okosun, Ike S
2010-11-01
This 2002 Medcen Foundation-funded study explored characteristics of problem drinking among 211 urban Venezuelan Native Americans of Arawak origin. Prevalence of problem drinking using Alcohol Use Disorders Identification Tests was 88.5% among men and 17.3% among women. Periodic binge drinking was marked by loss of control, failure to meet obligations, and alcohol-related trauma. Focus group participants noted that previous occasional binge drinking by men has been replaced by frequent male and female heavy weekend drinking, violence, and death. Limitations and implications are discussed. Awareness of high levels of problem drinking and desire for assistance present compelling mandates for community intervention efforts. PMID:20388009
NASA Technical Reports Server (NTRS)
Frink, N. T.; Lamar, J. E.
1980-01-01
A systematic water-tunnel study was made to determine the vortex breakdown characteristics of 43 strakes. The strakes were mounted on a 1/2-scale model of a Langley Research Center general research fighter fuselage model with a 44deg leading-edge-sweep trapezoidal wing. The analytically designed strake shapes provided examples of the effects of the primary design parameters (size, span, and slenderness) on vortex breakdown characteristics. These effects were analyzed in relation to the respective strake leading-edge suction distributions. Included were examples of the effects of detailed strake planform shaping. It was concluded that, consistent with the design criterion, those strakes with leading-edge suction distributions which increase more rapidly near, and have a higher value at, the spanwise tip of the strake produce a more stable vortex.
Lee, Erica H; Zhou, Qing; Ly, Jennifer; Main, Alexandra; Tao, Annie; Chen, Stephen H
2014-04-01
Using data from a socioeconomically diverse sample of Chinese American children (n = 258, aged 6-9 years) in immigrant families, we examined the concurrent relations among neighborhood economic disadvantage and concentration of Asian residents, parenting styles, and Chinese American children's externalizing and internalizing problems. Neighborhood characteristics were measured with 2000 U.S. Census tract-level data, parents (mostly mothers) rated their own parenting styles, and parents and teachers rated children's behavioral problems. Path analysis was conducted to test two hypotheses: (a) parenting styles mediate the relations between neighborhood characteristics and children's behavioral problems, and (b) children's behavioral problems mediate the relations between neighborhood and parenting styles. We found that neighborhood Asian concentration was positively associated with authoritarian parenting, which in turn was associated with Chinese American children's higher externalizing and internalizing problems (by parents' reports). In addition, neighborhood economic disadvantage was positively related to children's externalizing problems (by parents' reports), which in turn predicted lower authoritative parenting. The current results suggest the need to consider multiple pathways in the relations among neighborhood, family, and child adjustment, and they have implications for the prevention and intervention of behavioral problems in Chinese American children. PMID:24041263
Investigation into the effect of beam shape on melt pool characteristics using analytical modelling
NASA Astrophysics Data System (ADS)
Ahmed, N.; Voisey, K. T.; McCartney, D. G.
2010-05-01
An established analytical model is used to simulate an extended laser beam. Multiple Gaussian sources are superimposed to form a rectangular beam and results are compared with a single circular Gaussian source model as well as experimental results from a high power diode laser with a rectangular beam. Melt depth and melt pool profile and progression have been predicted by modeling, which are compared with experimental results from melting of Inconel 625. The model produced is shown to give a reasonable prediction of melt pool shape and can be usefully employed to help optimise overlap required for laser surface processing applications. The value of absorptivity used in the model can be used as a fitting parameter to optimise the match between experimental and predicted results.
Investigating Grade Nine Textbook Problems for Characteristics Related to Mathematical Literacy
ERIC Educational Resources Information Center
Gatabi, Abolfazl Rafiepour; Stacey, Kaye; Gooya, Zahra
2012-01-01
This study presents a content analysis of the new Iranian Grade 9 mathematics textbook and two Australian Year 9 mathematics textbooks, examining the extent to which the problems show characteristics associated in the literature with promoting mathematical literacy. The new Iranian book was produced to meet a range of needs including several well…
ERIC Educational Resources Information Center
Johnson, Cynthia R.; Turner, Kylan; Stewart, Patricia A.; Schmidt, Brianne; Shui, Amy; Macklin, Eric; Reynolds, Anne; James, Jill; Johnson, Susan L.; Manning Courtney, Patty; Hyman, Susan L.
2014-01-01
Many children with autism spectrum disorders (ASD) have co-occurring feeding problems. However, there is limited knowledge about how these feeding habits are related to other behavioral characteristics ubiquitous in ASD. In a relatively large sample of 256 children with ASD, ages 2-11, we examined the relationships between feeding and mealtime…
Investigating grade nine textbook problems for characteristics related to mathematical literacy
NASA Astrophysics Data System (ADS)
Rafiepour Gatabi, Abolfazl; Stacey, Kaye; Gooya, Zahra
2012-12-01
This study presents a content analysis of the new Iranian Grade 9 mathematics textbook and two Australian Year 9 mathematics textbooks, examining the extent to which the problems show characteristics associated in the literature with promoting mathematical literacy. The new Iranian book was produced to meet a range of needs including several well aligned with mathematical literacy for all students. Australia was selected as the comparison country because of its relatively high international achievement in mathematical literacy. Three comparable chapters in each book were analysed for these characteristics. When considering the percentages of problems showing each characteristic, there was considerable similarity between the textbooks. However, the Australian mathematics textbooks contain many more problems than the Iranian textbook and each chapter includes problems in a diverse range of contexts and the mathematical tasks range from simple applications of formulas to real world modelling although of a constrained nature. With many fewer problems, the Iranian textbook has considerably less diversity of context and very little opportunity for students to engage in mathematical modelling, the key process of mathematical literacy.
Jiang, Liuwei; Marcus, R Kenneth
2016-02-01
Capillary-channeled polymer (C-CP) fiber stationary phases are finding utility in the realms of protein analytics as well as downstream processing. We have recently described the modification of poly(ethylene terephthalate) (PET) C-CP fibers to affect amine-rich phases for the weak anion-exchange (WAX) separation of proteins. Polyethylenimine (PEI) is covalently coupled to the PET surface, with subsequent cross-linking imparted by treatment with 1,4-butanediol diglycidyl ether (BUDGE). These modifications yield vastly improved dynamic binding capacities over the unmodified fibers. We have also previously employed native (unmodified) nylon 6 C-CP fibers as weak anion/cation-exchange (mixed-mode) and hydrophobic interaction chromatography (HIC) phases for protein separations. Polyamide, nylon 6, consists of amide groups along the polymer backbone, with primary amines and carboxylic acid end groups. The analytical separation characteristics of these three amine-based C-CP fiber phases are compared here. Each of the C-CP fiber columns in this study was shown to be able to separate a bovine serum albumin/hemoglobin/lysozyme mixture at high mobile phase linear velocity (∼70 mm s(-1)) but with different elution characteristics. These differences reflect the types of protein-surface interactions that are occurring, based on the active group composition of the fiber surfaces. This study provides important fundamental understanding for the development of surface-modified C-CP fiber columns for protein separation. PMID:26345444
Methodical and pre-analytical characteristics of a multiplex cancer biomarker immunoassay
Hermann, Natalie; Dreßen, Katja; Schildberg, Frank A; Jakobs, Christopher; Holdenrieder, Stefan
2014-01-01
AIM: To test the methodical and pre-analytical performance of a new multiplex cancer biomarker panel using magnetic beads. METHODS: The MILLIPLEX® MAP Human Circulating Cancer Biomarker Magnetic Bead Panel 1 comprises the tumor markers carcinoembryonic antigen, alpha-fetoprotein, total prostate-specific antigen, cancer antigen 15-3, cancer antigen 19-9, cancer antigen 125, cytokeratine 19-fragment, β-human chorionic gonadotropin, human epididymis protein 4, osteopontin, prolactin, the cell death and angiogenesis markers soluble Fas, soluble Fas-ligand, tumor necrosis factor related apoptosis-inducing ligand, vascular endothelial growth factor and the immunological markers interleukin-6 (IL-6), IL-8, tumor necrosis factor-α, transforming growth factor α, fibroblast growth factor-2, macrophage migration inhibitory factor, leptin, hepatocyte growth factor, and stem cell factor. We determined intra- and inter-assay imprecision as well as dilution linearity using quality controls and serum pools. Furthermore, the stability of the 24 biomarkers examined in this panel was ascertained by testing the influence of different storage temperatures and time span before centrifugation. RESULTS: For all markers measured in the synthetic internal quality controls, the intra-assay imprecision ranged between 2.26% and 9.41%, while for 20 of 24 measured markers in the physiological serum pools, it ranged between 1.68% and 12.87%. The inter-assay imprecision ranged between 1.48%-17.12% for 23 biomarkers in synthetic, and between 4.59%-23.88% for 18 biomarkers in physiological quality controls. Here, single markers with very low concentration levels had increased imprecision rates. Dilution linearity was acceptable (70%-130% recovery) for 20 biomarkers. Regarding pre-analytical influencing factors, most markers were stable if blood centrifugation was delayed or if serum was stored for up to 24 h at 4 °C and 25 °C after centrifugation. Comparable results were obtained in serum and
Analytical investigation in bending characteristic of twisted stacked-tape cable conductor
NASA Astrophysics Data System (ADS)
Takayasu, Makoto; Chiesa, Luisa
2015-12-01
An analytical model to evaluate bending strains of a twisted stack-tape cable (TSTC) conductor has been developed. Through a comparison with experimental results obtained for a soldered 32-tape YBCO TSTC conductor, it has been found that a Perfect-Slip Model (PSM) taking into account the slipping between tapes in a stacked-tape cable during bending gives much better estimation of the bending performance compared to a No-Slip Model (NSM). In the PSM case the tapes can slip so that the internal longitudinal axial strain can be released. The longitudinal strains of compression and tension regions along the tape are balanced in one twist-pitch and cancel out evenly in a long cable. Therefore, in a cable the strains due to bending can be minimized. This is an important advantage of a TSTC conductor. The effect of the cable diameter size on the bending strain is also expected to be minor, and all tapes composing a TSTC conductor have the same strain response under bending, therefore the cable critical current can be characterized from a single tape behaviour.
Analytical derivation of thermodynamic characteristics of lipid bilayer from a flexible string model
NASA Astrophysics Data System (ADS)
Mukhin, Sergei I.; Baoukina, Svetlana
2005-06-01
We introduce a flexible string model of the hydrocarbon chain and derive an analytical expression for the lateral pressure profile across the hydrophobic core of the membrane. The pressure profile influences the functioning of the embedded proteins and is difficult to measure experimentally. In our model the hydrocarbon chain is represented as a flexible string of finite thickness with a given bending rigidity. In the mean-field approximation we substitute the entropic repulsion between neighboring chains in a lipid membrane by an effective potential. The effective potential is determined self-consistently. The arbitrary chain conformation is expanded over eigenfunctions of the self-adjoint operator of the chain energy density. The lateral pressure distribution across the bilayer is calculated using the path integral technique. We found that the pressure profile is mainly formed by the sum of the partial contributions of a few discrete lowest-energy “eigenconformations.” The dependences on temperature and area per lipid of the lateral pressure produced by the hydrocarbon chains are found. We also calculated the chain contribution to the area compressibility modulus and the temperature coefficient of area expansion.
Experimental and analytical transonic flutter characteristics of a geared-elevator configuration
NASA Technical Reports Server (NTRS)
Ruhlin, C. L.; Doggett, R. V., Jr.; Gregory, R. A.
1980-01-01
The flutter model represented the aft fuselage and empennage of a proposed supersonic transport airplane and had an all movable horizontal tail with a geared elevator. It was tested mounted from a sting in the transonic dynamics tunnel. Symmetric flutter boundaries were determined experimentally at Mach numbers from 0.7 to 1.14 for a geared elevator configuration (gear ratio of 2.8 to 1.0) and an ungeared elevator configuration (gear ratio of 1.0 to 1.0). Gearing the elevator increased the experimental flutter dynamic pressures about 20 percent. Flutter calculations were made for the geared elevator configuration by using two analytical methods based on subsonic lifting surface theory. Both methods analyzed the stabilizer and elevator as a single, deforming surface, but one method also allowed the elevator to be analyzed as hinged from the stabilizer. All analyses predicted lower flutter dynamic pressures than experiment with best agreement (within 12 percent) for the hinged elevator method. Considering the model as mounted from a flexible rather than rigid sting in the analyses, had only a slight effect on the flutter results but was significant in that a sting related vibration mode was identified as a potentially flutter critical mode.
NASA Astrophysics Data System (ADS)
Zlotnik, V. A.; Ledder, G.; Kacimov, A. R.
2014-12-01
Disposal of excessive runoff or treated sewage into wadis and ephemeral streams is a common practice and an important hydrological problem in many Middle Eastern countries. While chemical and biological properties of the injected treated wastewater may be different from those of the receiving aquifer, the density contrast between the two fluids can be small. Therefore, studies of the fluid interface for variable density fluids or water intrusion are not directly relevant in many Managed Aquifer Recharge (MAR) problems. Other factors, such as the transient nature of injection and lack of detailed aquifer information must be considered. The disposed water reaching the water table through the vadose zone creates groundwater mounds, deforms the original water table, and develops finite-size convex-concave lenses of treated water over receiving water. After cessation of infiltration, these mounds flatten, water levels become horizontal, and infiltrated water becomes fully embedded in the receiving aquifer. The shape of the treated water body is controlled by the aquifer parameters, the magnitude of ambient flow, and the duration, rate, and cyclicity of infiltration. In case of limited aquifer data, advective transport modeling offers the most appropriate tools for predicting plume shapes over time, but surprisingly little work has been done on this important 3D flow problem. We investigate the lateral and vertical spreading of infiltrated water combining techniques of spatial velocity analyses by Zlotnik and Ledder (1992, 1993) with particle tracking. This approach allows for evaluating the geometry of the plume and the protection zone, the flow development phases, and other temporal and spatial effects and results can be used in conditions of limited data availability and quality. (Funding was provided by the USAID, DAI Subcontract 1001624-12S-19745)
Faraji, Obeidollah; Ramazani, Abbas Ali; Hedaiati, Pouria; Aliabadi, Ali; Elhamirad, Samira; Valiee, Sina
2015-01-01
Background: Many factors influence the organizational commitment of employees. One of these factors is job designing since it affects the attitude, beliefs, and feelings of the organization employees. Objectives: We aimed to determine the relationship between job characteristics and organizational commitment among the employees of hospitals. Patients and Methods: In this descriptive and correlational study, 152 Iranian employees of the hospitals (physicians, nurses, and administrative staff) were selected through stratified random sampling. Data gathered using 3-part questionnaire of “demographic information”, “job characteristics model,” and “organizational commitment,” in 2011. Study data were analyzed using SPSS v. 16. Results: There was significant statistical correlation between organizational commitment and variables of educational level (P = 0.001) and job category (P = 0.001). Also, a direct and significant correlation existed between motivating potential score and job feedback on one hand and organizational commitment on the other hand (P = 0.014). Conclusions: According to the results, managers of the hospitals should increase staff’s commitment through paying attention to proper job designing. PMID:26734472
Jang, H.D.; Swaisgood, H.E. )
1990-12-01
Interaction of calcium with casein submicelles was investigated in CaCl2 and calcium phosphate buffers and with synthetic milk salt solutions using the technique of analytical affinity chromatography. Micelles that had been prepared by size exclusion chromatography with glycerolpropyl controlled-pore glass from fresh raw skim milk that had never been cooled, were dialyzed at room temperature against calcium-free imidazole buffer, pH 6.7. Resulting submicelles were covalently immobilized on succinamidopropyl controlled-pore glass (300-nm pore size). Using 45Ca to monitor the elution retardation, the affinity of free Ca2+ and calcium salt species was determined at temperatures of 20 to 40 degrees C and pH 6.0 to 7.5. Increasing the pH in this range or increasing the temperature strengthened the binding of calcium to submicelles, similar to previous observations with individual caseins. However, the enthalpy change obtained from the temperature dependence was considerably greater than that reported for alpha s1- and beta-caseins. Furthermore, the elution profiles for 45Ca in milk salt solutions were decidedly different from those in CaCl2 or calcium phosphate buffers and the affinities were also greater. For example, at pH 6.7 and 30 degrees C the average dissociation constant for the submicelle-calcium complex is 0.074 mM for CaCl2 and calcium phosphate buffers, vs 0.016 mM for the milk salt solution. The asymmetric frontal boundaries and higher average affinities observed with milk salts may be due to binding of calcium salts with greater affinity in addition to the binding of free Ca2+ in these solutions.
Pinsky, Benjamin A.; Sahoo, Malaya K.; Sandlund, Johanna; Kleman, Marika; Kulkarni, Medha; Grufman, Per; Nygren, Malin; Kwiatkowski, Robert; Baron, Ellen Jo; Tenover, Fred; Denison, Blake; Higuchi, Russell; Van Atta, Reuel; Beer, Neil Reginald; Carrillo, Alda Celena; Naraghi-Arani, Pejman; Mire, Chad E.; Ranadheera, Charlene; Grolla, Allen; Lagerqvist, Nina; Persing, David H.
2015-11-12
The recently developed Xpert® Ebola Assay is a novel nucleic acid amplification test for simplified detection of Ebola virus (EBOV) in whole blood and buccal swab samples. The assay targets sequences in two EBOV genes, lowering the risk for new variants to escape detection in the test. The objective of this report is to present analytical characteristics of the Xpert® Ebola Assay on whole blood samples. Our study evaluated the assay’s analytical sensitivity, analytical specificity, inclusivity and exclusivity performance in whole blood specimens. EBOV RNA, inactivated EBOV, and infectious EBOV were used as targets. The dynamic range of the assay, the inactivation of virus, and specimen stability were also evaluated. The lower limit of detection (LoD) for the assay using inactivated virus was estimated to be 73 copies/mL (95% CI: 51–97 copies/mL). The LoD for infectious virus was estimated to be 1 plaque-forming unit/mL, and for RNA to be 232 copies/mL (95% CI 163–302 copies/mL). The assay correctly identified five different Ebola viruses, Yambuku-Mayinga, Makona-C07, Yambuku-Ecran, Gabon-Ilembe, and Kikwit-956210, and correctly excluded all non-EBOV isolates tested. The conditions used by Xpert® Ebola for inactivation of infectious virus reduced EBOV titer by ≥6 logs. In conclusion, we found the Xpert® Ebola Assay to have high analytical sensitivity and specificity for the detection of EBOV in whole blood. It offers ease of use, fast turnaround time, and remote monitoring. The test has an efficient viral inactivation protocol, fulfills inclusivity and exclusivity criteria, and has specimen stability characteristics consistent with the need for decentralized testing. The simplicity of the assay should enable testing in a wide variety of laboratory settings, including remote laboratories that are not capable of performing highly complex nucleic acid amplification tests, and during outbreaks where time to detection is critical.
Pinsky, Benjamin A.; Sahoo, Malaya K.; Sandlund, Johanna; Kleman, Marika; Kulkarni, Medha; Grufman, Per; Nygren, Malin; Kwiatkowski, Robert; Baron, Ellen Jo; Tenover, Fred; Denison, Blake; Higuchi, Russell; Van Atta, Reuel; Beer, Neil Reginald; Carrillo, Alda Celena; Naraghi-Arani, Pejman; Mire, Chad E.; Ranadheera, Charlene; Grolla, Allen; Lagerqvist, Nina; Persing, David H.
2015-01-01
Background The recently developed Xpert® Ebola Assay is a novel nucleic acid amplification test for simplified detection of Ebola virus (EBOV) in whole blood and buccal swab samples. The assay targets sequences in two EBOV genes, lowering the risk for new variants to escape detection in the test. The objective of this report is to present analytical characteristics of the Xpert® Ebola Assay on whole blood samples. Methods and Findings This study evaluated the assay’s analytical sensitivity, analytical specificity, inclusivity and exclusivity performance in whole blood specimens. EBOV RNA, inactivated EBOV, and infectious EBOV were used as targets. The dynamic range of the assay, the inactivation of virus, and specimen stability were also evaluated. The lower limit of detection (LoD) for the assay using inactivated virus was estimated to be 73 copies/mL (95% CI: 51–97 copies/mL). The LoD for infectious virus was estimated to be 1 plaque-forming unit/mL, and for RNA to be 232 copies/mL (95% CI 163–302 copies/mL). The assay correctly identified five different Ebola viruses, Yambuku-Mayinga, Makona-C07, Yambuku-Ecran, Gabon-Ilembe, and Kikwit-956210, and correctly excluded all non-EBOV isolates tested. The conditions used by Xpert® Ebola for inactivation of infectious virus reduced EBOV titer by ≥6 logs. Conclusion In summary, we found the Xpert® Ebola Assay to have high analytical sensitivity and specificity for the detection of EBOV in whole blood. It offers ease of use, fast turnaround time, and remote monitoring. The test has an efficient viral inactivation protocol, fulfills inclusivity and exclusivity criteria, and has specimen stability characteristics consistent with the need for decentralized testing. The simplicity of the assay should enable testing in a wide variety of laboratory settings, including remote laboratories that are not capable of performing highly complex nucleic acid amplification tests, and during outbreaks where time to detection
Pinsky, Benjamin A.; Sahoo, Malaya K.; Sandlund, Johanna; Kleman, Marika; Kulkarni, Medha; Grufman, Per; Nygren, Malin; Kwiatkowski, Robert; Baron, Ellen Jo; Tenover, Fred; et al
2015-11-12
The recently developed Xpert® Ebola Assay is a novel nucleic acid amplification test for simplified detection of Ebola virus (EBOV) in whole blood and buccal swab samples. The assay targets sequences in two EBOV genes, lowering the risk for new variants to escape detection in the test. The objective of this report is to present analytical characteristics of the Xpert® Ebola Assay on whole blood samples. Our study evaluated the assay’s analytical sensitivity, analytical specificity, inclusivity and exclusivity performance in whole blood specimens. EBOV RNA, inactivated EBOV, and infectious EBOV were used as targets. The dynamic range of the assay,more » the inactivation of virus, and specimen stability were also evaluated. The lower limit of detection (LoD) for the assay using inactivated virus was estimated to be 73 copies/mL (95% CI: 51–97 copies/mL). The LoD for infectious virus was estimated to be 1 plaque-forming unit/mL, and for RNA to be 232 copies/mL (95% CI 163–302 copies/mL). The assay correctly identified five different Ebola viruses, Yambuku-Mayinga, Makona-C07, Yambuku-Ecran, Gabon-Ilembe, and Kikwit-956210, and correctly excluded all non-EBOV isolates tested. The conditions used by Xpert® Ebola for inactivation of infectious virus reduced EBOV titer by ≥6 logs. In conclusion, we found the Xpert® Ebola Assay to have high analytical sensitivity and specificity for the detection of EBOV in whole blood. It offers ease of use, fast turnaround time, and remote monitoring. The test has an efficient viral inactivation protocol, fulfills inclusivity and exclusivity criteria, and has specimen stability characteristics consistent with the need for decentralized testing. The simplicity of the assay should enable testing in a wide variety of laboratory settings, including remote laboratories that are not capable of performing highly complex nucleic acid amplification tests, and during outbreaks where time to detection is critical.« less
NASA Astrophysics Data System (ADS)
Wailliez, Sébastien E.
2014-03-01
In the two-body model, time of flight between two positions can be expressed as a single-variable function and a variety of formulations exist. Lambert’s problem can be solved by inverting such a function. In this article, a method which inverts Lagrange’s flight time equation and supports the problematic 180° transfer is proposed. This method relies on a Householder algorithm of variable order. However, unlike other iterative methods, it is semi-analytical in the sense that flight time functions are derived analytically to second order vs. first order finite differences. The author investigated the profile of Lagrange’s elliptic flight time equation and its derivatives with a special focus on their significance to the behaviour of the proposed method and the stated goal of guaranteed convergence. Possible numerical deficiencies were identified and dealt with. As a test, 28 scenarios of variable difficulty were designed to cover a wide variety of geometries. The context of this research being the orbit determination of artificial satellites and debris, the scenarios are representative of typical such objects in Low-Earth, Geostationary and Geostationary Transfer Orbits. An analysis of the computational impact of the quality of the initial guess vs. that of the order of the method was also done, providing clues for further research and optimisations (e.g. asteroids, long period comets, multi-revolution cases). The results indicate fast to very fast convergence in all test cases, they validate the numerical safeguards and also give a quantitative assessment of the importance of the initial guess.
NASA Technical Reports Server (NTRS)
Simpson, Myles A.; Mathur, Gopal P.
1992-01-01
Measurements conducted on a DC-9 aircraft test section to define the shell and cavity modes of the fuselage, understand its structural-acoustic coupling characteristics, and measure its response to different types of acoustic and vibration excitations are reported. The data were processed to generate spatial plots and wavenumber maps of the shell acceleration and cabin acoustic pressure field. Analysis and interpretation of the spatial plots and wavenumber maps showed that the only structural-acoustic coupling occurred at 105 Hz between the N=2 circumferential structural mode and the (n=2, p=0) circumferential cavity mode. The fuselage response to vibration excitation was found to be dominated by modes whose order increases with frequency.
This manual provides the pesticide chemist with a systematic protocol for the quality control of analytical procedures and the problems that arise in the analysis of human or environmental media. It also serves as a guide to the latest and most reliable methodology available for ...
NASA Astrophysics Data System (ADS)
Liu, Wen-Chao; Yao, Jun; Chen, Zhang-Xin
2014-02-01
Based on Huang's accurate tri-sectional nonlinear kinematic equation (1997), a dimensionless simplified mathematical model for nonlinear flow in one-dimensional semi-infinite long porous media with low permeability is presented for the case of a constant flow rate on the inner boundary. This model contains double moving boundaries, including an internal moving boundary and an external moving boundary, which are different from the classical Stefan problem in heat conduction: The velocity of the external moving boundary is proportional to the second derivative of the unknown pressure function with respect to the distance parameter on this boundary. Through a similarity transformation, the nonlinear partial differential equation (PDE) system is transformed into a linear PDE system. Then an analytical solution is obtained for the dimensionless simplified mathematical model. This solution can be used for strictly checking the validity of numerical methods in solving such nonlinear mathematical models for flows in low-permeable porous media for petroleum engineering applications. Finally, through plotted comparison curves from the exact analytical solution, the sensitive effects of three characteristic parameters are discussed. It is concluded that with a decrease in the dimensionless critical pressure gradient, the sensitive effects of the dimensionless variable on the dimensionless pressure distribution and dimensionless pressure gradient distribution becomemore serious; with an increase in the dimensionless pseudo threshold pressure gradient, the sensitive effects of the dimensionless variable become more serious; the dimensionless threshold pressure gradient (TPG) has a great effect on the external moving boundary but has little effect on the internal moving boundary. [Figure not available: see fulltext.
NASA Astrophysics Data System (ADS)
Liu, Wen-Chao; Yao, Jun; Chen, Zhang-Xin
2014-01-01
Based on Huang's accurate tri-sectional nonlinear kinematic equation (1997), a dimensionless simplified mathematical model for nonlinear flow in one-dimensional semi-infinite long porous media with low permeability is presented for the case of a constant flow rate on the inner boundary. This model contains double moving boundaries, including an internal moving boundary and an external moving boundary, which are different from the classical Stefan problem in heat conduction: The velocity of the external moving boundary is proportional to the second derivative of the unknown pressure function with respect to the distance parameter on this boundary. Through a similarity transformation, the nonlinear partial differential equation (PDE) system is transformed into a linear PDE system. Then an analytical solution is obtained for the dimensionless simplified mathematical model. This solution can be used for strictly checking the validity of numerical methods in solving such nonlinear mathematical models for flows in low-permeable porous media for petroleum engineering applications. Finally, through plotted comparison curves from the exact analytical solution, the sensitive effects of three characteristic parameters are discussed. It is concluded that with a decrease in the dimensionless critical pressure gradient, the sensitive effects of the dimensionless variable on the dimensionless pressure distribution and dimensionless pressure gradient distribution become more serious; with an increase in the dimensionless pseudo threshold pressure gradient, the sensitive effects of the dimensionless variable become more serious; the dimensionless threshold pressure gradient (TPG) has a great effect on the external moving boundary but has little effect on the internal moving boundary.
NASA Technical Reports Server (NTRS)
Damerow, W. P.; Murtaugh, J. P.; Burggraf, F.
1972-01-01
The flow characteristics of turbine airfoil cooling system components were experimentally investigated. Flow models representative of leading edge impingement, impingement with crossflow (midchord cooling), pin fins, feeder supply tube, and a composite model of a complete airfoil flow system were tested. Test conditions were set by varying pressure level to cover the Mach number and Reynolds number range of interest in advanced turbine applications. Selected geometrical variations were studied on each component model to determine these effects. Results of these tests were correlated and compared with data available in the literature. Orifice flow was correlated in terms of discharge coefficients. For the leading edge model this was found to be a weak function of hole Mach number and orifice-to-impinged wall spacing. In the impingement with crossflow tests, the discharge coefficient was found to be constant and thus independent of orifice Mach number, Reynolds number, crossflow rate, and impingement geometry. Crossflow channel pressure drop showed reasonable agreement with a simple one-dimensional momentum balance. Feeder tube orifice discharge coefficients correlated as a function of orifice Mach number and the ratio of the orifice-to-approach velocity heads. Pin fin data was correlated in terms of equivalent friction factor, which was found to be a function of Reynolds number and pin spacing but independent of pin height in the range tested.
Learning and teaching in small groups: characteristics, benefits, problems and approaches.
Jones, R W
2007-08-01
Small group learning may be defined as a group of learners demonstrating three common characteristics; active participation, a specific task and reflection. This article provides an overview of small group learning and teaching, describes the characteristics of this form of small group work, benefits, problems, potential causes of less than optimal sessions, and summarises specific approaches. These include tutorials, free-discussion groups, brainstorming, snowballing, buzz groups, paired (or one-to-one) discussion, clinical teaching, simulations, seminars, plenary sessions, problem-based learning, team-based learning, role plays, games and IT approaches. The article concludes with an emphasis on the importance of the teacher and a check list for use when planning, teaching and evaluating a small group session. PMID:18020080
Russell, David F.; Neiman, Alexander B.; Lindner, Benjamin
2013-01-01
Stochastic signals with pronounced oscillatory components are frequently encountered in neural systems. Input currents to a neuron in the form of stochastic oscillations could be of exogenous origin, e.g. sensory input or synaptic input from a network rhythm. They shape spike firing statistics in a characteristic way, which we explore theoretically in this report. We consider a perfect integrate-and-fire neuron that is stimulated by a constant base current (to drive regular spontaneous firing), along with Gaussian narrow-band noise (a simple example of stochastic oscillations), and a broadband noise. We derive expressions for the nth-order interval distribution, its variance, and the serial correlation coefficients of the interspike intervals (ISIs) and confirm these analytical results by computer simulations. The theory is then applied to experimental data from electroreceptors of paddlefish, which have two distinct types of internal noisy oscillators, one forcing the other. The theory provides an analytical description of their afferent spiking statistics during spontaneous firing, and replicates a pronounced dependence of ISI serial correlation coefficients on the relative frequency of the driving oscillations, and furthermore allows extraction of certain parameters of the intrinsic oscillators embedded in these electroreceptors. PMID:23966844
2011-01-01
The photocurrent in bilayer polymer photovoltaic cells is dominated by the exciton dissociation efficiency at donor/acceptor interface. An analytical model is developed for the photocurrent-voltage characteristics of the bilayer polymer/TiO2 photovoltaic cells. The model gives an analytical expression for the exciton dissociation efficiency at the interface, and explains the dependence of the photocurrent of the devices on the internal electric field, the polymer and TiO2 layer thicknesses. Bilayer polymer/TiO2 cells consisting of poly[2-methoxy-5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and TiO2, with different thicknesses of the polymer and TiO2 films, were prepared for experimental purposes. The experimental results for the prepared bilayer MEH-PPV/TiO2 cells under different conditions are satisfactorily fitted to the model. Results show that increasing TiO2 or the polymer layer in thickness will reduce the exciton dissociation efficiency in the device and further the photocurrent. It is found that the photocurrent is determined by the competition between the exciton dissociation and charge recombination at the donor/acceptor interface, and the increase in photocurrent under a higher incident light intensity is due to the increased exciton density rather than the increase in the exciton dissociation efficiency. PMID:21711905
Bauermeister, Christoph; Schwalger, Tilo; Russell, David F; Neiman, Alexander B; Lindner, Benjamin
2013-01-01
Stochastic signals with pronounced oscillatory components are frequently encountered in neural systems. Input currents to a neuron in the form of stochastic oscillations could be of exogenous origin, e.g. sensory input or synaptic input from a network rhythm. They shape spike firing statistics in a characteristic way, which we explore theoretically in this report. We consider a perfect integrate-and-fire neuron that is stimulated by a constant base current (to drive regular spontaneous firing), along with Gaussian narrow-band noise (a simple example of stochastic oscillations), and a broadband noise. We derive expressions for the nth-order interval distribution, its variance, and the serial correlation coefficients of the interspike intervals (ISIs) and confirm these analytical results by computer simulations. The theory is then applied to experimental data from electroreceptors of paddlefish, which have two distinct types of internal noisy oscillators, one forcing the other. The theory provides an analytical description of their afferent spiking statistics during spontaneous firing, and replicates a pronounced dependence of ISI serial correlation coefficients on the relative frequency of the driving oscillations, and furthermore allows extraction of certain parameters of the intrinsic oscillators embedded in these electroreceptors. PMID:23966844
2014-01-01
A possibility of the creation of potentiometric biosensor by adsorption of enzyme urease on zeolite was investigated. Several variants of zeolites (nano beta, calcinated nano beta, silicalite, and nano L) were chosen for experiments. The surface of pH-sensitive field-effect transistors was modified with particles of zeolites, and then the enzyme was adsorbed. As a control, we used the method of enzyme immobilization in glutaraldehyde vapour (without zeolites). It was shown that all used zeolites can serve as adsorbents (with different effectiveness). The biosensors obtained by urease adsorption on zeolites were characterized by good analytical parameters (signal reproducibility, linear range, detection limit and the minimal drift factor of a baseline). In this work, it was shown that modification of the surface of pH-sensitive field-effect transistors with zeolites can improve some characteristics of biosensors. PMID:24636423
NASA Astrophysics Data System (ADS)
Shelyakina, Margaryta K.; Soldatkin, Oleksandr O.; Arkhypova, Valentyna M.; Kasap, Berna O.; Akata, Burcu; Dzyadevych, Sergei V.
2014-03-01
A possibility of the creation of potentiometric biosensor by adsorption of enzyme urease on zeolite was investigated. Several variants of zeolites (nano beta, calcinated nano beta, silicalite, and nano L) were chosen for experiments. The surface of pH-sensitive field-effect transistors was modified with particles of zeolites, and then the enzyme was adsorbed. As a control, we used the method of enzyme immobilization in glutaraldehyde vapour (without zeolites). It was shown that all used zeolites can serve as adsorbents (with different effectiveness). The biosensors obtained by urease adsorption on zeolites were characterized by good analytical parameters (signal reproducibility, linear range, detection limit and the minimal drift factor of a baseline). In this work, it was shown that modification of the surface of pH-sensitive field-effect transistors with zeolites can improve some characteristics of biosensors.
Shevyrin, Vadim; Melkozerov, Vladimir; Nevero, Alexander; Eltsov, Oleg; Shafran, Yuri; Morzherin, Yuri; Lebedev, Albert T
2015-08-01
Illicit new psychoactive substances (NPS) are a serious threat to health throughout the world. Such NPS do not usually pass preliminary pharmacological trials. In 2014, we identified a series of five new synthetic cannabinoids with an indazole-3-carboxamide structure bearing an N-1-methoxycarbonylalkyl group. The compounds have very high cannabimimetic activity which has caused mass severe intoxication and deaths. The compounds were identified by means of gas chromatography-mass spectrometry (GC-MS), including high-resolution mass spectrometry (GC-HRMS), ultra-high-performance liquid chromatography-high-resolution tandem mass spectrometry (UHPLC-HRMS(2)), and (1)H and (13)C nuclear magnetic resonance spectroscopy (NMR). The peculiarities of mass-spectral fragmentation of the compounds after electron ionization (EI) ionization and collision-induced dissociation (CID) were studied. The analytical characteristics reported for the compounds will enable their identification in a variety of materials seized from criminals.Graphical Abstract. PMID:25893797
Przyjazny, Andrzej; Kokosa, John M
2002-11-22
Headspace solvent microextraction (HSM) is a novel method of sample preparation for chromatographic analysis. It involves exposing a microdrop of high-boiling point organic solvent extruded from the needle tip of a gas chromatographic syringe to the headspace above a sample. Volatile organic compounds are extracted and concentrated in the microdrop. Next, the microdrop is retracted into the microsyringe and injected directly into the chromatograph. HSM has a number of advantages, including renewable drop (no sample carryover), low cost, simplicity and ease of use, short time of analysis, high sensitivity and low detection limits, good precision, minimal solvent use, and no need for instrument modification. This paper presents analytical characteristics of HSM as applied to the determination of benzene, toluene, ethylbenzene and xylenes in water. PMID:12456104
Oswald, Tasha M; Beck, Jonathan S; Iosif, Ana-Maria; McCauley, James B; Gilhooly, Leslie J; Matter, John C; Solomon, Marjorie
2016-04-01
Mathematics achievement in autism spectrum disorder (ASD) has been understudied. However, the ability to solve applied math problems is associated with academic achievement, everyday problem-solving abilities, and vocational outcomes. The paucity of research on math achievement in ASD may be partly explained by the widely-held belief that most individuals with ASD are mathematically gifted, despite emerging evidence to the contrary. The purpose of the study was twofold: to assess the relative proportions of youth with ASD who demonstrate giftedness versus disability on applied math problems, and to examine which cognitive (i.e., perceptual reasoning, verbal ability, working memory) and clinical (i.e., test anxiety) characteristics best predict achievement on applied math problems in ASD relative to typically developing peers. Twenty-seven high-functioning adolescents with ASD and 27 age- and Full Scale IQ-matched typically developing controls were assessed on standardized measures of math problem solving, perceptual reasoning, verbal ability, and test anxiety. Results indicated that 22% of the ASD sample evidenced a mathematics learning disability, while only 4% exhibited mathematical giftedness. The parsimonious linear regression model revealed that the strongest predictor of math problem solving was perceptual reasoning, followed by verbal ability and test anxiety, then diagnosis of ASD. These results inform our theories of math ability in ASD and highlight possible targets of intervention for students with ASD struggling with mathematics. PMID:26418313
2013-01-01
Background The past decade has witnessed a growing body of research on welfare state characteristics and health inequalities but the picture is, despite this, inconsistent. We aim to review this research by focusing on theoretical and methodological differences between studies that at least in part may lead to these mixed findings. Methods Three reviews and relevant bibliographies were manually explored in order to find studies for the review. Related articles were searched for in PubMed, Web of Science and Google Scholar. Database searches were done in PubMed and Web of Science. The search period was restricted to 2005-01-01 to 2013-02-28. Fifty-four studies met the inclusion criteria. Results Three main approaches to comparative welfare state research are identified; the Regime approach, the Institutional approach, and the Expenditure approach. The Regime approach is the most common and regardless of the empirical regime theory employed and the amendments made to these, results are diverse and contradictory. When stratifying studies according to other features, not much added clarity is achieved. The Institutional approach shows more consistent results; generous policies and benefits seem to be associated with health in a positive way for all people in a population, not only those who are directly affected or targeted. The Expenditure approach finds that social and health spending is associated with increased levels of health and smaller health inequalities in one way or another but the studies are few in numbers making it somewhat difficult to get coherent results. Conclusions Based on earlier reviews and our results we suggest that future research should focus less on welfare regimes and health inequalities and more on a multitude of different types of studies, including larger analyses of social spending and social rights in various policy areas and how these are linked to health in different social strata. But, we also need more detailed evaluation of
Identification of dynamic characteristics of flexible rotors as dynamic inverse problem
NASA Technical Reports Server (NTRS)
Roisman, W. P.; Vajingortin, L. D.
1991-01-01
The problem of dynamic and balancing of flexible rotors were considered, which were set and solved as the problem of the identification of flexible rotor systems, which is the same as the inverse problem of the oscillation theory dealing with the task of the identifying the outside influences and system parameters on the basis of the known laws of motion. This approach to the problem allows the disclosure the picture of disbalances throughout the rotor-under-test (which traditional methods of flexible rotor balancing, based on natural oscillations, could not provide), and identify dynamic characteristics of the system, which correspond to a selected mathematical model. Eventually, various methods of balancing were developed depending on the special features of the machines as to their design, technology, and operation specifications. Also, theoretical and practical methods are given for the flexible rotor balancing at far from critical rotation frequencies, which does not necessarily require the knowledge forms of oscillation, dissipation, and elasticity and inertia characteristics, and to use testing masses.
Sleep Characteristics, Sleep Problems, and Associations to Quality of Life among Psychotherapists.
Schlarb, Angelika A; Reis, Dorota; Schröder, Annette
2012-01-01
Sleep problems, especially insomnia, are a common complaint among adults. International studies have shown prevalence rates between 4.7 and 36.2% for sleep difficulties in general, whereas 13.1-28.1% report insomnia symptoms. Sleep problems are associated with lower social and academic performance and can have a severe impact on psychological and physical health. Psychotherapists are suppliers within the public health system. The goal of this study was to outline sleep characteristics, prevalence of sleep problems, insomnia, and associations of quality of life among psychotherapists. A total of 774 psychotherapists (74.7% women; mean age 46 years) participated in the study. Sleep characteristics, sleep problems, well-being, life satisfaction and workload, as well as specific job demands, were assessed via a questionnaire. Analyses revealed that more than 4.2% of the surveyed psychotherapists have difficulties falling asleep, 12.7% often wake up in the night, and 26.6% feel tired, and 3.4% think that their interrupted sleep affects work performance. About 44.1% of them suffer from symptoms of insomnia. Path models showed that insomnia is significantly related to well-being and life satisfaction. PMID:23471477
The linearized characteristics method and its application to practical nonlinear supersonic problems
NASA Technical Reports Server (NTRS)
Ferri, Antonio
1952-01-01
The methods of characteristics has been linearized by assuming that the flow field can be represented as a basic flow field determined by nonlinearized methods and a linearized superposed flow field that accounts for small changes of boundary conditions. The method has been applied to two-dimensional rotational flow where the basic flow is potential flow and to axially symmetric problems where conical flows have been used as the basic flows. In both cases the method allows the determination of the flow field to be simplified and the numerical work to be reduced to a few calculations. The calculations of axially symmetric flow can be simplified if tabulated values of some coefficients of the conical flow are obtained. The method has also been applied to slender bodies without symmetry and to some three-dimensional wing problems where two-dimensional flow can be used as the basic flow. Both problems were unsolved before in the approximation of nonlinear flow.
Building characteristics associated with moisture related problems in 8,918 Swedish dwellings.
Hägerhed-Engman, Linda; Bornehag, Carl-Gustaf; Sundell, Jan
2009-08-01
Moisture problems in buildings have in a number of studies been shown to increase the risk for respiratory symptoms. The study Dampness in Buildings and Health (DBH) was initiated with the aim to identify health relevant exposures related to dampness in buildings. A questionnaire study about home environment with a focus on dampness problems and health was conducted in one county of Sweden (8,918 homes, response rate 79%). Building characteristics that were associated with one or more of the dampness indicators were for single-family houses, older houses, flat-roofed houses built in the 1960s and 1970s, houses with a concrete slab on the ground that were built before 1983. Moreover, tenancy and earlier renovation due to mould or moisture problems was strongly associated with dampness. A perception of dry air was associated with window-pane condensation, e.g. humid indoor air. PMID:19557598
ERIC Educational Resources Information Center
Berg-Nielsen, Turid Suzanne; Solheim, Elisabet; Belsky, Jay; Wichstrom, Lars
2012-01-01
In this study, we explored informant characteristics as determinants of parent-teacher disagreement on preschoolers' psychosocial problems. Teacher characteristics were included in the analyses, in addition to child and parent factors. Psychosocial problems of 732 4-year olds from a Norwegian community sample were assessed by parents and teachers…
Psychosocial problems in patients with newly diagnosed diabetes: number and characteristics.
Rane, K; Wajngot, A; Wändell, P E; Gåfvels, C
2011-09-01
Early in the course of diabetes, it is important to identify and support patients whose psychosocial situations and reactions to the diagnosis may affect their ability to adjust or take adequate responsibility for self-care. We aimed to identify (a) the number and characteristics of patients, 18-65 years, newly diagnosed with diabetes, who needed psychosocial interventions and (b) the type of psychosocial problems they had. A total of 106 patients (72 men) were included in the study. Interviews showed that 41.5% had psychosocial problems. Fifteen dropped out early in the study; 38% of those remaining had psychosocial problems (PSP). More than half had problems with their life situation; most commonly in relationships. About a third had problems related to diabetes, most commonly, work-related. Compared to other participants, PSP patients lived in more strained social situations, especially regarding personal finances and social support. More of the PSP patients were anxious and depressed. They used negative coping strategies more often and more frequently expected that diabetes would negatively affect their future. In conclusion, early in the course of diabetes, screening instruments should be used to identify PSP patients. Treatment by medical social workers skilled in diabetes care should be offered. PMID:21636163
ERIC Educational Resources Information Center
Rubio, Guillermo; del Valle, Rafael
2004-01-01
The study proves that a didactical model based in a method to solve word problems of increasing complexity which uses a numerical approach was essential to develop the analytical ability and the competent use of the algebraic language with students from three different performance levels in elementary algebra. It is shown that before using the…
NASA Astrophysics Data System (ADS)
Dúmet-Montoya, H. S.; Caminha, G. B.; Makler, M.
2013-12-01
Context. The Navarro-Frenk-White (NFW) density profile is often used to model gravitational lenses. For κs ≲ 0.1 (where κs is a parameter that defines the normalization of the NFW lens potential) - corresponding to galaxy and galaxy group mass scales - high numerical precision is required to accurately compute several quantities in the strong lensing regime. Aims: We obtain analytic solutions for several lensing quantities for circular NFW models and their elliptical (ENFW) and pseudo-elliptical (PNFW) extensions, on the typical scales where gravitational arcs are expected to be formed, in the κs ≲ 0.1 limit, by establishing their domain of validity. Methods: We approximate the deflection angle of the circular NFW model and derive analytic expressions for the convergence and shear for the PNFW and ENFW models. We obtain the constant distortion curves (including the tangential critical curve), which are used to define the domain of validity of the approximations, by employing a figure-of-merit to compare with the exact numerical solutions. We compute the deformation cross section as a further check of the validity of the approximations. Results: We derive analytic solutions for iso-convergence contours and constant distortion curves for the models considered here. We also obtain the deformation cross section, which is given in closed form for the circular NFW model and in terms of a one-dimensional integral for the elliptical ones. In addition, we provide a simple expression for the ellipticity of the iso-convergence contours of the pseudo-elliptical models and the connection of characteristic convergences among the PNFW and ENFW models. Conclusions: We conclude that the set of solutions derived here is generally accurate for κs ≲ 0.1. For low ellipticities, values up to κs ≃ 0.18 are allowed. On the other hand, the mapping among PNFW and the ENFW models is valid up to κs ≃ 0.4. The solutions derived in this work can be used to speed up numerical
Sijtsema, J J; Oldehinkel, A J; Veenstra, R; Verhulst, F C; Ormel, J
2014-06-01
Both structural (i.e., SES, familial psychopathology, family composition) and dynamic (i.e., parental warmth and rejection) family characteristics have been associated with aggressive and depressive problem development. However, it is unclear to what extent (changes in) dynamic family characteristics have an independent effect on problem development while accounting for stable family characteristics and comorbid problem development. This issue was addressed by studying problem development in a large community sample (N = 2,230; age 10-20) of adolescents using Linear Mixed models. Paternal and maternal warmth and rejection were assessed via the Egna Minnen Beträffande Uppfostran for Children (EMBU-C). Aggressive and depressive problems were assessed via subscales of the Youth/Adult Self-Report. Results showed that dynamic family characteristics independently affected the development of aggressive problems. Moreover, maternal rejection in preadolescence and increases in paternal rejection were associated with aggressive problems, whereas decreases in maternal rejection were associated with decreases in depressive problems over time. Paternal and maternal warmth in preadolescence was associated with fewer depressive problems during adolescence. Moreover, increases in paternal warmth were associated with fewer depressive problems over time. Aggressive problems were a stable predictor of depressive problems over time. Finally, those who increased in depressive problems became more aggressive during adolescence, whereas those who decreased in depressive problems became also less aggressive. Besides the effect of comorbid problems, problem development is to a large extent due to dynamic family characteristics, and in particular to changes in parental rejection, which leaves much room for parenting-based interventions. PMID:24043499
NASA Astrophysics Data System (ADS)
Alhussan, K.; Morozov, D. O.; Stankevich, Yu. A.; Stanchits, L. K.; Stepanov, K. L.
2014-07-01
The thermal properties of hot air needed for describing the hypersonic motion of bodies in the Earth's atmosphere have been considered. Such motion, as is known, is accompanied by the propagation of strong shock waves analogous to waves generated by powerful explosions. Calculations have been made and data banks have been created for the equations of state and thermal characteristics of air in the temperature and density ranges corresponding to velocities of motion of bodies of up to 10 km/s at altitudes of 0-100 km. The formulation of the problem of hypersonic motion in the absence of thermodynamic equilibrium is discussed.
NASA Technical Reports Server (NTRS)
Lamar, J. E.; Frink, N. T.
1981-01-01
Sixteen analytically and empirically designed strakes have been tested experimentally on a wing-body at three subcritical speeds in such a way as to isolate the strake-forebody loads from the wing-afterbody loads. Analytical estimates for these longitudinal results are made using the suction analogy and the augmented vortex lift concepts. The synergistic data are reasonably well estimated or bracketed by the high- and low-angle-of-attack vortex lift theories over the Mach number range and up to maximum lift or strake-vortex breakdown over the wing. Also, the strake geometry is very important in the maximum lift value generated and the lift efficiency of a given additional area. Increasing size and slenderness ratios are important is generating lift efficiently, but similar efficiency can also be achieved by designing a strake with approximately half the area of the largest gothic strake tested. These results correlate well with strake-vortex-breakdown observations in the water tunnel.
NASA Technical Reports Server (NTRS)
Gorton, C. A.; Lakshminarayana, B.
1980-01-01
The inviscid and viscid effects existing within the passages of a three bladed axial flow inducer operating at a flow coefficient of 0.065 are investigated. The blade static pressure and blade limiting streamline angle distributions were determined and the three components of mean velocity, turbulence intensities, and turbulence stresses were measured at locations inside the inducer blade passage utilizing a rotating three sensor hotwire probe. Applicable equations were derived for the hotwire data reduction analysis and solved numerically to obtain the appropriate flow parameters. The three dimensional inviscid flow in the inducer was predicted by numerically solving the exact equations of motion, and the three dimensional viscid flow was predicted by incorporating the dominant viscous terms into the exact equations. The analytical results are compared with the experimental measurements and design values where appropriate. Radial velocities are found to be of the same order as axial velocities within the inducer passage, confirming the highly three dimensional characteristic of inducer flow. Total relative velocity distribution indicate a substantial velocity deficiency near the tip at mid-passage which expands significantly as the flow proceeds toward the inducer trailing edge. High turbulence intensities and turbulence stresses are concentrated within this core region. Considerable wake diffusion occurs immediately downstream of the inducer trailing edge to decay this loss core. Evidence of boundary layer interactions, blade blockage effects, radially inward flows, annulus wall effects, and backflows are all found to exist within the long, narrow passages of the inducer.
NASA Technical Reports Server (NTRS)
Chin, J. S.; Li, W. M.; Wang, X. F.
1986-01-01
The variation of spray characteristics along a radial distance downstream of a pressure-swirl atomizer was measured by laser light-scattering technology. An analytical model was developed to predict the variation of spray characteristics along the radial distance. A comparison of the predicted and experimental data showed excellent agreement. Therefore, the spray model proposed, although relatively simple, is correct and can be used, with some expansion and modification of the prepared model, to predict more complicated spray systems.
National Helpline for Problem Gambling: A Profile of Its Users' Characteristics
Bastiani, Luca; Fea, Maurizio; Potente, Roberta; Luppi, Claudia; Lucchini, Fabio; Molinaro, Sabrina
2015-01-01
Gambling has seen a significant increase in Italy in the last 10 years and has rapidly become a public health issue, and for these reasons the first National Helpline for Problem Gambling (GR-Helpline) has been established. The aims of this study are to describe the GR-Helpline users' characteristics and to compare the prevalence rates of the users with those of moderate-risk/problematic gamblers obtained from the national survey (IPSAD 2010-2011). Statistical analysis was performed on data obtained from the counselling sessions (phone/e-mail/chat) carried out on 5,805 users (57.5% gamblers; 42.5% families/friends). This confirms that the problems related to gambling concern not only the gamblers but also their families and friends. Significant differences were found between gamblers and families/friends involving gender (74% of gamblers were male; 76.9% of families/friends were female), as well as age-classes and geographical area. Female gamblers had a higher mean age (47.3 versus 40.2 years) and preferred nonstrategy-based games. Prevalence rates of GR-Helpline users and of moderate risk/problematic gamblers were correlated (Rho = 0.58; p = 0.0113). The results highlight the fact that remote access to counselling can be an effective means of promoting treatment for problem gamblers who do not otherwise appeal directly for services. PMID:26064772
Technology Transfer Automated Retrieval System (TEKTRAN)
Maintaining the postharvest quality of fresh-cut fruit after processing and throughout distribution and marketing is a major challenge facing the fresh-cut fruit industry. Analytical quality characteristics of packaged fresh-cut watermelon slices from non-treated and 1-methylcyclopropene (1-MCP)- a...
NASA Astrophysics Data System (ADS)
Courbage, M.
1982-04-01
We study some mathematical problems posed in nonequilibrium statistical mechanics and subdynamics theory developed by Prigogine and coworkers. We study in the superspace of the Hilbert-Schmidt operators the solution of the Liouville-von Neumann equation. The application in this frame of the spectral deformation methods yields expression of analytic continuations of a class of matrix elements of the resolvent of the Liouville-von Neumann operator, and this allows the analytic continuation of the collision and destruction operators. However, it is impossible to obtain simultaneously analytic continuation of the creation operator in this frame. The above results will be used in the second part of the article in order to study the pseudo-Markovian equation.
NASA Astrophysics Data System (ADS)
Yang, Gang; Tang, Zheng; Dai, Hongwei
Through analyzing the dynamics characteristic of maximum neural network with an added vertex, we find that the solution quality is mainly determined by the added vertex weights. In order to increase maximum neural network ability, a stochastic nonlinear self-feedback and flexible annealing strategy are embedded in maximum neural network, which makes the network more powerful to escape local minima and be independent of the initial values. Simultaneously, we present that solving ability of maximum neural network is dependence on problem. We introduce a new parameter into our network to improve the solving ability. The simulation in k random graph and some DIMACS clique instances in the second DIMACS challenge shows that our improved network is superior to other algorithms in light of the solution quality and CPU time.
Johnson, Cynthia R; Turner, Kylan; Stewart, Patricia A; Schmidt, Brianne; Shui, Amy; Macklin, Eric; Reynolds, Anne; James, Jill; Johnson, Susan L; Manning Courtney, Patty; Hyman, Susan L
2014-09-01
Many children with autism spectrum disorders (ASD) have co-occurring feeding problems. However, there is limited knowledge about how these feeding habits are related to other behavioral characteristics ubiqitious in ASD. In a relatively large sample of 256 children with ASD, ages 2-11, we examined the relationships between feeding and mealtime behaviors and social, communication, and cognitive levels as well repetitive and ritualistic behaviors, sensory behaviors, and externalizing and internalizing behaviors. Finally, we examined whether feeding habits were predictive of nutritional adequacy. In this sample, we found strong associations between parent reported feeding habits and (1) repetitive and ritualistic behaviors, (2) sensory features, and (3) externalizing and internalizing behavior. There was a lack of association between feeding behaviors and the social and communication deficits of ASD and cognitive levels. Increases in the degree of problematic feeding behaviors predicted decrements in nutritional adequacy. PMID:24664635
NASA Astrophysics Data System (ADS)
Song, Qing-Wen; Zhang, Yu-Ming; Zhang, Yi-Men; Lü, Hong-Liang; Chen, Feng-Ping; Zheng, Qing-Li
2009-12-01
A new analytical model for reverse characteristics of 4H-SiC merged PN-Schottky diodes (MPS or JBS) is developed. To accurately calculate the reverse characteristics of the 4H-SiC MPS diode, the relationship between the electric field at the Schottky contact and the reverse bias is analytically established by solving the cylindrical Poisson equation after the channel has pinched off. The reverse current density calculated from the Wentzel-Kramers-Brillouin (WKB) theory is verified by comparing it with the experimental result, showing that they are in good agreement with each other. Moreover, the effects of P-region spacing (S) and P-junction depth (Xj) on the characteristics of 4H-SiC MPS are analysed, and are particularly useful for optimizing the design of the high voltage MPS diodes.
NASA Technical Reports Server (NTRS)
Hong, D. C.; Langer, J. S.
1986-01-01
An analytic approach to the problem of predicting the widths of fingers in a Hele-Shaw cell is presented. The analysis is based on the WKB technique developed recently for dealing with the effects of surface tension in the problem of dendritic solidification. It is found that the relation between the dimensionless width lambda and the dimensionless group of parameters containing the surface tension, nu, has the form lambda - 1/2 = nu exp 2/3 in the limit of small nu.
ERIC Educational Resources Information Center
Oshiro, Claudia Kami Bastos; Kanter, Jonathan; Meyer, Sonia Beatriz
2012-01-01
Functional Analytic Psychotherapy (FAP) is emerging as an effective psychotherapy for psychiatric clinical cases. However, there is little research demonstrating the process of change of FAP. The present study evaluated the introduction and withdrawal of FAP interventions on therapy-interfering verbal behaviors of two participants who were in…
ERIC Educational Resources Information Center
Baker, Amy J. L.; Archer, Marc; Curtis, Patrick
2007-01-01
This study aimed to determine what youth characteristics were associated with emotional and behavioral problems exhibited within the first three months of placement in residential treatment centers (RTCs) in a sample of youth from 20 agencies in 13 states. Two primary research questions were addressed: 1) What characteristics were associated with…
ERIC Educational Resources Information Center
Patkin, Dorit; Gazit, Avikam
2011-01-01
This article aims to present the findings of a research which investigated the effect of a difference in word formulation and mathematical characteristics of story problems on their successful solution by preservice mathematics teachers (students) and practising mathematics teachers. The findings show that in the case of a problem with a…
Pesin, Yakov B.; Niu, Xun; Latash, Mark L.
2010-01-01
We consider the problem of what is being optimized in human actions with respect to various aspects of human movements and different motor tasks. From the mathematical point of view this problem consists of finding an unknown objective function given the values at which it reaches its minimum. This problem is called the inverse optimization problem. Until now the main approach to this problems has been the cut-and-try method, which consists of introducing an objective function and checking how it reflects the experimental data. Using this approach, different objective functions have been proposed for the same motor action. In the current paper we focus on inverse optimization problems with additive objective functions and linear constraints. Such problems are typical in human movement science. The problem of muscle (or finger) force sharing is an example. For such problems we obtain sufficient conditions for uniqueness and propose a method for determining the objective functions. To illustrate our method we analyze the problem of force sharing among the fingers in a grasping task. We estimate the objective function from the experimental data and show that it can predict the force-sharing pattern for a vast range of external forces and torques applied to the grasped object. The resulting objective function is quadratic with essentially non-zero linear terms. PMID:19902213
NASA Astrophysics Data System (ADS)
Knosowski, Yvonne; von Lieres, Eric; Schneider, Adrian
1999-06-01
In this paper we consider the non-characteristic Cauchy problem 0266-5611/15/3/307/img1" ALT="(equation)"/> where 0266-5611/15/3/307/img2" ALT="(equation)"/> with appropriate coefficient functions a, b and c. Assuming that the Cauchy data icons/Journals/Common/varphi" ALT="varphi are given inexactly by a function icons/Journals/Common/varphi" ALT="varphiicons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/> satisfying ||icons/Journals/Common/varphi" ALT="varphi" ALIGN="TOP"/>-icons/Journals/Common/varphi" ALT="varphi" ALIGN="TOP"/>icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/>||Hricons/Journals/Common/le" ALT="le" ALIGN="TOP"/> icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="TOP"/> for some ricons/Journals/Common/le" ALT="le" ALIGN="TOP"/>0 and that f(y,t): = u(l,y,t) exists and belongs to Hs(icons/Journals/Common/BbbR" ALT="BbbR" ALIGN="TOP"/>n-1 × icons/Journals/Common/BbbR" ALT="BbbR" ALIGN="TOP"/>) for some sicons/Journals/Common/in" ALT="in" ALIGN="TOP"/>icons/Journals/Common/BbbR" ALT="BbbR" ALIGN="TOP"/>, it is desired to calculate f from the improper data icons/Journals/Common/varphi" ALT="varphi" ALIGN="TOP"/>icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="MIDDLE"/>. This problem is well known to be severely ill-posed: a small perturbation in the Cauchy data may cause a dramatically large error in the solution. In this paper the following mollification method is suggested for this problem: if the Cauchy data are given inexactly then we mollify them by projection on elements of Meyers multiresolution approximation {Vj}jicons/Journals/Common/in" ALT="in" ALIGN="TOP"/>icons/Journals/Common/BbbZ" ALT="BbbZ" ALIGN="TOP"/>. Within every space Vj the solution of the above problem depends continuously on the data, and we can find a mollification parameter J depending on the noise level icons/Journals/Common/varepsilon" ALT="varepsilon" ALIGN="TOP"/> in the Cauchy data such that the error estimation between the
NASA Astrophysics Data System (ADS)
Butt, N.; Pidlisecky, A.; Ganshorn, H.; Cockett, R.
2015-12-01
The software company 3 Point Science has developed three interactive learning programs designed to teach, test and practice visualization skills and geoscience concepts. A study was conducted with 21 geoscience students at the University of Calgary who participated in 2 hour sessions of software interaction and written pre and post-tests. Computer and SMART touch table interfaces were used to analyze user interaction, problem solving methods and visualization skills. By understanding and pinpointing user problem solving methods it is possible to reconstruct viewpoints and thought processes. This could allow us to give personalized feedback in real time, informing the user of problem solving tips and possible misconceptions.
Bifocal contact lenses: History, types, characteristics, and actual state and problems
Toshida, Hiroshi; Takahashi, Kozo; Sado, Kazushige; Kanai, Atsushi; Murakami, Akira
2008-01-01
Since people who wear contact lenses (CL) often continue using CL even when they develop presbyopia, there are growing expectations for bifocal CL. To understand actual state and problems, history, types, and their characteristics are summarized in this review. Bifocal CL have a long history over 70 years. Recently, bifocal CL have achieved remarkable progress. However, there still is an impression that prescription of bifocal CL is not easy. It should also be remembered that bifocal CL have limits, including limited addition for near vision, as well as the effects of aging and eye diseases in the aged, such as dry eye, astigmatism, cataract, etc. Analysis of the long-term users of bifocal CL among our patients has revealed the disappearance of bifocal CL that achieved unsatisfactory vision and poor contrast compared with those provided by other types of CL. Changing the prescription up to 3 times for lenses of the same brand may be appropriate. Lenses that provide poor contrast sensitivity, suffer from glare, or give unsatisfactory vision have been weeded out. The repeated replacement of products due to the emergence of improved or new products will be guessed. PMID:19668441
Tsai, Y.M.; Crane, R.A. )
1992-05-01
Heat transfer across surfaces in imperfect contact occurs in many practical situations. Since the thermal contact conductance problem has appeared in the literature, substantial efforts have been made to estimate the thermal conductance across the interface. Some of the techniques recently developed of estimating thermal contact conductance are based on experimental temperature data at one or several interior positions of the contacting solids and the calculation of the temperature at these locations for known contact conductance. Consequently, an accurate and efficient method for computing temperature distributions because quite important. FDM and FEM are most widely used. However, for most contact conductance computation methods, only the temperatures at the contacting regions and several other positions near the interface need to be determined, so the general FDM and FEM are not particularly efficient in solving this problem. This paper presents an analytical temperature distribution solution to the one-dimensional symmetric system with heat flux on one outside surface and insulation on the other. This analysis provides a theoretical basis for transient measurement of thermal contact conductance. While it is common practice in steady-state measurements to use a water-cooled heat sink, it is possible to limit the transient solution to time interval prior to any detectable temperature increase at the cold end. This effectively eliminates the need for water cooling and permits the use of an insulated boundary. The analytical solution to the mentioned problem obtained shows that for a symmetric system the temperature distribution solution includes two sets of distinct eigenfunctions.
Lorenz, Ralph D
2012-08-01
Thermal drilling has been applied to studies of glaciers on Earth and proposed for study of the martian ice caps and the crust of Europa. Additionally, inadvertent thermal drilling by radioisotope sources released from the breakup of a space vehicle is of astrobiological concern in that this process may form a downward-propagating "warm little pond" that could convey terrestrial biota to a habitable environment. A simple analytic solution to the asymptotic slow-speed case of thermal drilling is noted and used to show that the high thermal conductivity of the low-temperature ice on Europa and Titan makes thermal drilling qualitatively more difficult than at Mars. It is shown that an isolated General Purpose Heat Source (GPHS) "brick" can drill effectively on Earth or Mars, whereas on Titan or Europa with ice at 100 K, the source would stall and become stuck in the ice with a surface temperature of <200 K. PMID:22897131
ERIC Educational Resources Information Center
Ghoneim, Nahed Mohamed Mahmoud
2013-01-01
The current study focused on the problems which students encounter while listening to the English language, the mental processes they activate in listening comprehension, and the strategies they use in different phases of comprehension. Also, it aimed to find out whether there were any differences between advanced and intermediate students in…
A Meta-Analytic and Qualitative Review of Online versus Face-to-Face Problem-Based Learning
ERIC Educational Resources Information Center
Jurewitsch, Brian
2012-01-01
Problem-based learning (PBL) is an instructional strategy that is poised for widespread application in the current, growing, on-line digital learning environment. While enjoying a track record as a defensible strategy in face-to-face learning settings, the research evidence is not clear regarding PBL in on-line environments. A review of the…
ERIC Educational Resources Information Center
Thorsland, Martin Nils
The purposes of this study were: (1) to evaluate the effectiveness of audio-tutorial (A-T) instruction and (2) to identify, classify and study differences in problem solving approach using a theoretical framework derived from the ideas of D. P. Ausubel. Seventy of 420 students taking a college introductory non-calculus physics course used A-T…
NASA Astrophysics Data System (ADS)
Bashiri, Mahdi; Karimi, Hossein
2012-07-01
Quadratic assignment problem (QAP) is a well-known problem in the facility location and layout. It belongs to the NP-complete class. There are many heuristic and meta-heuristic methods, which are presented for QAP in the literature. In this paper, we applied 2-opt, greedy 2-opt, 3-opt, greedy 3-opt, and VNZ as heuristic methods and tabu search (TS), simulated annealing, and particle swarm optimization as meta-heuristic methods for the QAP. This research is dedicated to compare the relative percentage deviation of these solution qualities from the best known solution which is introduced in QAPLIB. Furthermore, a tuning method is applied for meta-heuristic parameters. Results indicate that TS is the best in 31%of QAPs, and the IFLS method, which is in the literature, is the best in 58 % of QAPs; these two methods are the same in 11 % of test problems. Also, TS has a better computational time among heuristic and meta-heuristic methods.
Bereketli Zafeirakopoulos, Ilke Erol Genevois, Mujde
2015-09-15
Life Cycle Assessment is a tool to assess, in a systematic way, the environmental aspects and its potential environmental impacts and resources used throughout a product's life cycle. It is widely accepted and considered as one of the most powerful tools to support decision-making processes used in ecodesign and sustainable production in order to learn about the most problematic parts and life cycle phases of a product and to have a projection for future improvements. However, since Life Cycle Assessment is a cost and time intensive method, companies do not intend to carry out a full version of it, except for large corporate ones. Especially for small and medium sized enterprises, which do not have enough budget for and knowledge on sustainable production and ecodesign approaches, focusing only on the most important possible environmental aspect is unavoidable. In this direction, finding the right environmental aspect to work on is crucial for the companies. In this study, a multi-criteria decision-making methodology, Analytic Network Process is proposed to select the most relevant environmental aspect. The proposed methodology aims at providing a simplified environmental assessment to producers. It is applied for a hand blender, which is a member of the Electrical and Electronic Equipment family. The decision criteria for the environmental aspects and relations of dependence are defined. The evaluation is made by the Analytic Network Process in order to create a realistic approach to inter-dependencies among the criteria. The results are computed via the Super Decisions software. Finally, it is observed that the procedure is completed in less time, with less data, with less cost and in a less subjective way than conventional approaches. - Highlights: • We present a simplified environmental assessment methodology to support LCA. • ANP is proposed to select the most relevant environmental aspect. • ANP deals well with the interdependencies between aspects and
Behaviour-Emotional Characteristics of Primary-School Children Rated as Having Language Problems
ERIC Educational Resources Information Center
Lundervold, A. J.; Heimann, M.; Manger, T.
2008-01-01
Background: Primary-school teachers are expected to detect problems related to language function, but the teachers' evaluations may be heavily influenced by gender and classroom behaviour. Aim: To investigate the relationship between language problems (LPs) and behaviour-emotional problems as rated by primary-school teachers. Methods: All…
Not Available
2006-06-01
In the Analytical Microscopy group, within the National Center for Photovoltaic's Measurements and Characterization Division, we combine two complementary areas of analytical microscopy--electron microscopy and proximal-probe techniques--and use a variety of state-of-the-art imaging and analytical tools. We also design and build custom instrumentation and develop novel techniques that provide unique capabilities for studying materials and devices. In our work, we collaborate with you to solve materials- and device-related R&D problems. This sheet summarizes the uses and features of four major tools: transmission electron microscopy, scanning electron microscopy, the dual-beam focused-ion-beam workstation, and scanning probe microscopy.
NASA Astrophysics Data System (ADS)
Xiong, Jianyin; Liu, Cong; Zhang, Yinping
2012-02-01
A general analytical model for characterizing emission and sorption of formaldehyde and volatile organic compounds (VOCs) in single-layer building materials is developed. Compared with traditional models, the present model can be applicable for four kinds of typical physical processes, i.e., emission in ventilated and airtight chambers, and sorption in these two types of chambers. Based on the general analytical model, a novel method is proposed to determine the characteristic parameters (the diffusion coefficient, Dm, and the material/air partition coefficient, K) of formaldehyde and VOC sorption in ventilated and airtight chambers. It establishes a linear relationship between the logarithm of dimensionless excess concentration and sorption time, and the Dm and K can be conveniently obtained from the slope and intercept of the regression line. The results of applying the present model are compared with the experimental data in the literature. The good agreement between them not only validates the model but also demonstrates that the measured characteristic parameters are accurate and reliable. The general analytical model should prove useful for unified characterization and prediction of emission/sorption in building materials as well as for parameter measurement.
NASA Technical Reports Server (NTRS)
Gorton, C. A.; Lakshminarayana, B.
1974-01-01
The effort conducted to gather additional understanding of the complex inviscid and viscid effects existing within the passages of a three-bladed axial flow inducer operating at a flow coefficient of 0.065 is summarized. The experimental investigations included determination of the blade static pressure and blade limiting streamline angle distributions, and measurement of the three components of mean velocity, turbulence intensities and turbulence stresses at locations inside the inducer blade passage utilizing a rotating three-sensor hotwire probe. Applicable equations were derived for the hotwire data reduction analysis and solved numerically to obtain the appropriate flow parameters. Analytical investigations were conducted to predict the three-dimensional inviscid flow in the inducer by numerically solving the exact equations of motion, and to approximately predict the three-dimensional viscid flow by incorporating the dominant viscous terms into the exact equations. The analytical results are compared with the experimental measurements and design values where appropriate.
NASA Technical Reports Server (NTRS)
Longuski, James M.; Mcronald, Angus D.
1988-01-01
In previous work the problem of injecting the Galileo and Ulysses spacecraft from low earth orbit into their respective interplanetary trajectories has been discussed for the single stage (Centaur) vehicle. The central issue, in the event of spherically distributed injection errors, is what happens to the vehicle? The difficulties addressed in this paper involve the multi-stage problem since both Galileo and Ulysses will be utilizing the two-stage IUS system. Ulysses will also include a third stage: the PAM-S. The solution is expressed in terms of probabilities for total percentage of escape, orbit decay and reentry trajectories. Analytic solutions are found for Hill's Equations of Relative Motion (more recently called Clohessy-Wiltshire Equations) for multi-stage injections. These solutions are interpreted geometrically on the injection sphere. The analytic-geometric models compare well with numerical solutions, provide insight into the behavior of trajectories mapped on the injection sphere and simplify the numerical two-dimensional search for trajectory families.
ERIC Educational Resources Information Center
Lecavalier, Luc
2006-01-01
Parents or teachers rated 487 non-clinically referred young people with Pervasive Developmental Disorders on the Nisonger Child Behavior Rating Form. The objectives of the study were to examine the relative prevalence of specific behavior problems, assess the impact of subject characteristics, and derive an empirical classification of behavioral…
ERIC Educational Resources Information Center
Farmer, Thomas W.; Goforth, Jennifer B.; Clemmer, Jason T.; Thompson, Jana H.
2004-01-01
The authors examined school discipline problems in relation to academic and interpersonal characteristics of students in a middle school of a rural low-income community. The sample comprised 259 students (83 boys, 176 girls)--all of whom were African American--and reflected the community's public school attendance. School records were examined,…
ERIC Educational Resources Information Center
Ozgen, Kemal; Alkan, Huseyin
2012-01-01
The present study examined the potential relationship between 1st and 5th year secondary school pre-service mathematics teachers' skills in understanding, method, modelling, verification, and extension dimensions of problem solving and their learning style characteristics. The data consisted of the skills pre-service teachers demonstrated in the…
Characteristics of a Cognitive Tool That Helps Students Learn Diagnostic Problem Solving
ERIC Educational Resources Information Center
Danielson, Jared A.; Mills, Eric M.; Vermeer, Pamela J.; Preast, Vanessa A.; Young, Karen M.; Christopher, Mary M.; George, Jeanne W.; Wood, R. Darren; Bender, Holly S.
2007-01-01
Three related studies replicated and extended previous work (J.A. Danielson et al. (2003), "Educational Technology Research and Development," 51(3), 63-81) involving the Diagnostic Pathfinder (dP) (previously Problem List Generator [PLG]), a cognitive tool for learning diagnostic problem solving. In studies 1 and 2, groups of 126 and 113…
Against All Odds: Problem-Solving Strategies and Behavioural Characteristics of Novice Students
ERIC Educational Resources Information Center
Chang, Pei-Fen; Lin, Miao-Chen
2015-01-01
This study investigates problem-solving difficulties of novices in a classroom setting, using a German instructional tool, the Fischertechnik kit of approximately 400 parts. In order to analyse the students' thinking processes as they solved the problems, verbal protocol analysis (VPA) was used to record the students'' thinking…
ERIC Educational Resources Information Center
Matson, Johnny L.; Horovitz, Max; Sipes, Megan
2011-01-01
The prevalence of toileting problems was assessed in 153 adults with intellectual disability (ID) using the "Profile of Toileting Issues" ("POTI") and comparisons were made based on various demographic variables. The most frequently endorsed problems were "has toileting accidents during the day," "has toileting accidents during the night," "has…
NASA Technical Reports Server (NTRS)
Sutliff, Daniel L.; Walker, Bruce E.
2014-01-01
An Ultrasonic Configurable Fan Artificial Noise Source (UCFANS) was designed, built, and tested in support of the NASA Langley Research Center's 14x22 wind tunnel test of the Hybrid Wing Body (HWB) full 3-D 5.8% scale model. The UCFANS is a 5.8% rapid prototype scale model of a high-bypass turbofan engine that can generate the tonal signature of proposed engines using artificial sources (no flow). The purpose of the program was to provide an estimate of the acoustic shielding benefits possible from mounting an engine on the upper surface of a wing; a flat plate model was used as the shielding surface. Simple analytical simulations were used to preview the radiation patterns - Fresnel knife-edge diffraction was coupled with a dense phased array of point sources to compute shielded and unshielded sound pressure distributions for potential test geometries and excitation modes. Contour plots of sound pressure levels, and integrated power levels, from nacelle alone and shielded configurations for both the experimental measurements and the analytical predictions are presented in this paper.
NASA Technical Reports Server (NTRS)
Thompson, W. C.; Boghani, A. B.; Leland, T. J. W.
1977-01-01
An investigation was conducted to compare the steady-state and dynamic flow characteristics of an axial-flow fan which had been used previously as the air supply fan for some model air cushion landing system studies. Steady-state flow characteristics were determined in the standard manner by using differential orifice pressures for the flow regime from free flow to zero flow. In this same regime, a correlative technique was established so that fan inlet and outlet pressures could be used to measure dynamic flow as created by a rotating damper. Dynamic tests at damper frequencies up to 5 Hz showed very different flow characteristics when compared with steady-state flow, particularly with respect to peak pressures and the pressure-flow relationship at fan stall and unstall. A generalized, rational mathematical fan model was developed based on physical fan parameters and a steady-state flow characteristic. The model showed good correlation with experimental tests at damper frequencies up to 5 Hz.
Technology Transfer Automated Retrieval System (TEKTRAN)
A novel hybrid muskmelon has been bred specifically for use by the fresh-cut industry in winter. Quality characteristics of fresh-cut chunks from the hybrid were compared to those of its inbred parental lines and to those of a commercial netted muskmelon (cantaloupe) and a non-netted muskmelon (hon...
NASA Technical Reports Server (NTRS)
Graham, A. B.
1977-01-01
Small- and large-scale models of supersonic cruise fighter vehicles were used to determine the effectiveness of airframe/propulsion integration concepts for improved low-speed performance and stability and control characteristics. Computer programs were used for engine/airframe sizing studies to yield optimum vehicle performance.
Jaffee, Sara R.
2010-01-01
Objective The first objective of this study was to test for sex differences in four childhood sexual abuse characteristics---penetration, substantiation, perpetrator familial status, and multi-maltreatment---in a national sample of youth. The second objective was to test for sex differences in how these abuse characteristics were associated with victims’ emotional and behavioral problems. Methods The sample was drawn from the National Survey of Child and Adolescent Well-Being, a sample of children investigated by United States child welfare services. Youth in the current study (n = 573, including 234 adolescents) were investigated for alleged sexual abuse. Logistic regression and multivariate analysis of covariance were used to test for sex differences in abuse characteristics, and to determine whether sex moderated associations between abuse characteristics and emotional and behavioral problems. Results Girls were more likely than boys to have their abuse substantiated and to experience penetrative abuse (although differences in penetration status did not emerge among adolescents). Substantiation status and child age were positively associated with caregiver-reported internalizing and externalizing symptoms. Sex did not moderate the relationship between abuse characteristics and youth emotional and behavioral problems. Conclusions Sexual abuse characteristics might not be highly predictive factors when making decisions about services needs. Furthermore, there may not be a strong empirical basis for operating on the assumption that one sex is more vulnerable to negative consequences of abuse than the other, or that abuse affects girls and boys differently. The processes explaining why some victims exhibit more impairment than others are likely complex. PMID:20400178
NASA Technical Reports Server (NTRS)
Murphy, A. C.
1981-01-01
Experimental data and correlative analytical results on the flutter and gust response characteristics of a torsion-free-wing (TFW) fighter airplane model are presented. TFW consists of a combined wing/boom/canard surface and was tested with the TFW free to pivot in pitch and with the TFW locked to the fuselage. Flutter and gust response characteristics were measured in the Langley Transonic Dynamics Tunnel with the complete airplane model mounted on a cable mount system that provided a near free flying condition. Although the lowest flutter dynamic pressure was measured for the wing free configuration, it was only about 20 deg less than that for the wing locked configuration. However, no appreciable alleviation of the gust response was measured by freeing the wing.
NASA Astrophysics Data System (ADS)
Blokhintsev, L. D.; Nikitina, L. I.; Orlov, Yu. V.; Savin, D. A.
2014-08-01
In the present work one- and two-channel approaches using the expansion of the effective-range function K( E) in powers of energy E are applied to obtain the asymptotic normalization coefficients (ANCs) and vertex constants (VCs) for the d + α system. The coefficients of the K( E) expansion are found by fitting the d α phase shifts. By analytic continuation of K( E) thus obtained to the corresponding poles the ANCs and VCs for D wave d α resonances with J π = 1+, 2+, 3+ are calculated for the first time. The 1+-resonance and the bound state of 6Li ( J π = 1+) are considered jointly in the two-channel ( S + D) effective-range approach and the ANCs and VCs for the ground 6Li state are found.
Tyteca, Eva; Desmet, Gert
2015-07-17
Some valuable insights have been obtained in the inherent fitting problems when trying to predict the retention time of complex, multi-modal retention modes such as encountered in HILIC and SFC. In this study, we used mathematical models with known input parameters to generate different sets of numerical test curves representative for systems exhibiting a complex, non-LSS dual retention behavior. Subsequently, we tried to fit these data sets using some popular (non-linear) literature models. Even in cases where a physical fitting model exists (e.g., the mixed model in case of pure additive adsorptive and partitioning retention), the fitting quality can only be expected to be relatively good (prediction errors expressed in terms of a normalized resolution error ɛRs) when carefully selecting the scouting runs and the appropriate starting values for the fitting algorithm. The latter can best be done using a comprehensive grid search scanning a wide range of different starting values. This becomes even more important when no good physical model is available and one has to use a non-physical fitting model, such as the empirical Neue-model. The use of higher-order models is found to be quasi indispensable to keep the prediction errors on the order of some ΔRs=0.05. Also, the choice of the scouting runs becomes even more important using these higher-order models. For highly retained compounds we recommend using scouting runs with long tG/t0-values or to include a run with a higher fraction of eluting solvent at the start of the gradient. When trying to predict gradient retention, errors with which the isocratic retention behavior is fitted are much less important for high retention factors k than errors made in the range of k near the one at the point of elution. The results obtained with a so-called segmented Neue-model (containing 7 parameters) were less good and thus practically not interesting (because of the high number of initial runs). PMID:26044381
Russell, G.A.
1991-06-01
Electromagnetic Interference (EMI) problems have resulted in the redesign of the SANDAC V computer case and shielding of its connecting cables. In this report are detailed discussions on the use of computer models and of the tests performed to solve the EMI problems. Included is documentation on the specific changes made to the SANDAC V computer case and the shielding done on the connecting cables. Also documented are the current EMI capabilities relative to MIL Std. 461.
Cierniak, Robert; Lorent, Anna
2016-09-01
The main aim of this paper is to investigate properties of our originally formulated statistical model-based iterative approach applied to the image reconstruction from projections problem which are related to its conditioning, and, in this manner, to prove a superiority of this approach over ones recently used by other authors. The reconstruction algorithm based on this conception uses a maximum likelihood estimation with an objective adjusted to the probability distribution of measured signals obtained from an X-ray computed tomography system with parallel beam geometry. The analysis and experimental results presented here show that our analytical approach outperforms the referential algebraic methodology which is explored widely in the literature and exploited in various commercial implementations. PMID:27289536
Chahine, G.L.; Genoux, P.F.; Johnson, V.E. Jr.; Frederick, G.S.
1984-09-01
Waterjet nozzles (STRATOJETS) have been developed which achieve passive structuring of cavitating submerged jets into discrete ring vortices, and which possess cavitation incipient numbers six times higher than obtained with conventional cavitating jet nozzles. In this study we developed analytical and numerical techniques and conducted experimental work to gain an understanding of the basic phenomena involved. The achievements are: (1) a thorough analysis of the acoustic dynamics of the feed pipe to the nozzle; (2) a theory for bubble ring growth and collapse; (3) a numerical model for jet simulation; (4) an experimental observation and analysis of candidate second-generation low-sigma STRATOJETS. From this study we can conclude that intensification of bubble ring collapse and design of highly resonant feed tubes can lead to improved drilling rates. The models here described are excellent tools to analyze the various parameters needed for STRATOJET optimizations. Further analysis is needed to introduce such important factors as viscosity, nozzle-jet interaction, and ring-target interaction, and to develop the jet simulation model to describe the important fine details of the flow field at the nozzle exit.
Learning-Method Choices and Personal Characteristics in Solving a Physical Education Problem
ERIC Educational Resources Information Center
Vincent-Morin, Madeleine; Lafont, Lucile
2005-01-01
The goal of this study was to identify the relationships between the learning choices made by pupils and their personal characteristics, including cognitive style (field dependence--independence), a motivational variable (feeling of self-efficacy), and a cognitive variable (task representation). The participants were 64 twelve-year-old sixth…
ERIC Educational Resources Information Center
Flessner, Christopher A.; Woods, Douglas W.
2006-01-01
In this study, the authors collected data on the demographic characteristics, phenomenology, and social and economic impact of skin picking. A total of 92 participants completed an anonymous, Internet-based survey through a link to the Trichotillomania Learning Center's home page. Results indicated that skin pickers experienced social,…
ERIC Educational Resources Information Center
Gaudiano, Brandon A.; Brown, Lily A.; Miller, Ivan W.
2012-01-01
Objective: The objective was to learn about the characteristics of psychotherapists who use energy meridian techniques (EMTs). Methods: We conducted an Internet-based survey of the practices and attitudes of licensed psychotherapists. Results: Of 149 survey respondents (21.4% social workers), 42.3% reported that they frequently use or are inclined…
ERIC Educational Resources Information Center
Barry, Adam E.; Misra, Ranjita; Dennis, Maurice
2006-01-01
Driving a vehicle under the influence of alcohol is a major public health concern. By distinguishing the type of individuals violating driving while intoxicated (DWI) sanctions, intervention programs will be better suited to reduce drinking and driving. The purpose of this study was to examine the personal characteristics of DWI offenders and…
ERIC Educational Resources Information Center
Mergendoller, John R.; Maxwell, Nan L.; Bellisimo, Yolanda
2006-01-01
This study compared the effectiveness of problem-based learning (PBL) and traditional instructional approaches in developing high-school students' macroeconomics knowledge and examined whether PBL was differentially effective with students demonstrating different levels of four aptitudes: verbal ability, interest in economics, preference for group…
ERIC Educational Resources Information Center
Nitschke, Kai; Ruh, Nina; Kappler, Sonja; Stahl, Christoph; Kaller, Christoph P.
2012-01-01
Understanding the functional neuroanatomy of planning and problem solving may substantially benefit from better insight into the chronology of the cognitive processes involved. Based on the assumption that regularities in cognitive processing are reflected in overtly observable eye-movement patterns, here we recorded eye movements while…
Costs of the New Information Technologies in Education: Characteristics and Problems of Measurement.
ERIC Educational Resources Information Center
Eicher, J. C.
Although an increasing number of theoretical analyses and evaluations have been conducted since microcomputer technology was developed and introduced into classrooms, few new studies have been undertaken on the costs of these new information technologies (NIT). This report focuses on the methodological problems that must be solved in order to…
ERIC Educational Resources Information Center
Khan, Anwar; Yusoff, Rosman Bin Md; Isa, Khairunesa Binti
2016-01-01
Scholarly work and research are globally known as stressful and challenging. Teachers may develop different psychological health problems once they are exposed to workplace stressors. Considering it as a serious issue of education sector, this study has examined the linkages between prevalent workplace stressors and psychological health problems…
Some Characteristics and Personality Problems of Children Who Are Victims of Child Abuse.
ERIC Educational Resources Information Center
Hildreth, Gladys J.; And Others
This paper explores the concept of child abuse. The analysis begins by explaining the problems evident in defining child abuse, and presents the historical development of child abuse prevention. A theoretical discussion on personality development is also included. The second section of the paper describes results of a research project designed to…
Holzhauser, Thomas; Ree, Ronald van; Poulsen, Lars K; Bannon, Gary A
2008-10-01
There is detailed guidance on how to perform bioinformatic analyses and enzymatic degradation studies for genetically modified crops under consideration for approval by regulatory agencies; however, there is no consensus in the scientific community on the details of how to perform IgE serum studies. IgE serum studies are an important safety component to acceptance of genetically modified crops when the introduced protein is novel, the introduced protein is similar to known allergens, or the crop is allergenic. In this manuscript, we describe the characteristics of the reagents, validation of assay performance, and data analysis necessary to optimize the information obtained from serum testing of novel proteins and genetically modified (GM) crops and to make results more accurate and comparable between different investigations. PMID:18727951
NASA Astrophysics Data System (ADS)
Velychko, T. P.; Soldatkin, O. O.; Melnyk, V. G.; Marchenko, S. V.; Kirdeciler, S. K.; Akata, B.; Soldatkin, A. P.; El'skaya, A. V.; Dzyadevych, S. V.
2016-02-01
Development of a conductometric biosensor for the urea detection has been reported. It was created using a non-typical method of the recombinant urease immobilization via adsorption on nanoporous particles of silicalite. It should be noted that this biosensor has a number of advantages, such as simple and fast performance, the absence of toxic compounds during biosensor preparation, and high reproducibility (RSD = 5.1 %). The linear range of urea determination by using the biosensor was 0.05-15 mM, and a lower limit of urea detection was 20 μM. The bioselective element was found to be stable for 19 days. The characteristics of recombinant urease-based biomembranes, such as dependence of responses on the protein and ion concentrations, were investigated. It is shown that the developed biosensor can be successfully used for the urea analysis during renal dialysis.
Velychko, T P; Soldatkin, О О; Melnyk, V G; Marchenko, S V; Kirdeciler, S K; Akata, B; Soldatkin, A P; El'skaya, A V; Dzyadevych, S V
2016-12-01
Development of a conductometric biosensor for the urea detection has been reported. It was created using a non-typical method of the recombinant urease immobilization via adsorption on nanoporous particles of silicalite. It should be noted that this biosensor has a number of advantages, such as simple and fast performance, the absence of toxic compounds during biosensor preparation, and high reproducibility (RSD = 5.1 %). The linear range of urea determination by using the biosensor was 0.05-15 mM, and a lower limit of urea detection was 20 μM. The bioselective element was found to be stable for 19 days. The characteristics of recombinant urease-based biomembranes, such as dependence of responses on the protein and ion concentrations, were investigated. It is shown that the developed biosensor can be successfully used for the urea analysis during renal dialysis. PMID:26911570
Hoffman, A. J.; Lee, J. C.
2013-07-01
A new time-dependent neutron transport method based on the method of characteristics (MOC) has been developed. Whereas most spatial kinetics methods treat time dependence through temporal discretization, this new method treats time dependence by defining the characteristics to span space and time. In this implementation regions are defined in space-time where the thickness of the region in time fulfills an analogous role to the time step in discretized methods. The time dependence of the local source is approximated using a truncated Taylor series expansion with high order derivatives approximated using backward differences, permitting the solution of the resulting space-time characteristic equation. To avoid a drastic increase in computational expense and memory requirements due to solving many discrete characteristics in the space-time planes, the temporal variation of the boundary source is similarly approximated. This allows the characteristics in the space-time plane to be represented analytically rather than discretely, resulting in an algorithm comparable in implementation and expense to one that arises from conventional time integration techniques. Furthermore, by defining the boundary flux time derivative in terms of the preceding local source time derivative and boundary flux time derivative, the need to store angularly-dependent data is avoided without approximating the angular dependence of the angular flux time derivative. The accuracy of this method is assessed through implementation in the neutron transport code DeCART. The method is employed with variable-order local source representation to model a TWIGL transient. The results demonstrate that this method is accurate and more efficient than the discretized method. (authors)
NASA Astrophysics Data System (ADS)
Boukhili, W.; Mahdouani, M.; Bourguiga, R.; Puigdollers, J.
2015-07-01
Bottom-contact p-type small-molecule copper phthalocyanine (CuPc) thin film transistors (TFTs) with different channel lengths have been fabricated by thermal evaporation. The influence of the channel length on the current-voltage characteristics of the fabricated transistors were investigated in the linear and saturation regimes. The devices exhibit excellent p-type operation characteristics. Results show that devices with smaller channel length (L = 2.5 μm and 5 μm) present the best electrical performance, in terms of drain current value, field effect mobility and subthreshold slope. Saturation field-effect mobilities of 1.7 × 10-3 cm2 V-1 s-1 and 1 × 10-3 cm2 V-1 s-1 were obtained for TFTs with channel lengths of L = 2.5 μm and L = 5 μm, respectively. Transmission line method was used to study the dependence of the contact resistance with the channel length. Contact resistance becomes dominant with respect to the channel resistance only in the case of short channel devices (L = 2.5 μm and 5 μm). It was also found that the field effect mobility is extremely dependent on the channel length dimension. Finally, an analytical model has been developed to reproduce the dependence of the transfer characteristics with the channel length and the obtained data are in good agreement with the experimental results for all fabricated devices.
NASA Technical Reports Server (NTRS)
Abel, I.
1979-01-01
An analytical technique for predicting the performance of an active flutter-suppression system is presented. This technique is based on the use of an interpolating function to approximate the unsteady aerodynamics. The resulting equations are formulated in terms of linear, ordinary differential equations with constant coefficients. This technique is then applied to an aeroelastic model wing equipped with an active flutter-suppression system. Comparisons between wind-tunnel data and analysis are presented for the wing both with and without active flutter suppression. Results indicate that the wing flutter characteristics without flutter suppression can be predicted very well but that a more adequate model of wind-tunnel turbulence is required when the active flutter-suppression system is used.
Analysis of self-similar problems of imploding shock waves by the method of characteristics
NASA Astrophysics Data System (ADS)
Nakamura, Y.
1983-05-01
The asymptotic self-similar form of cylindrically or spherically imploding shock waves is extracted by numerically solving non-self-similar problems. The shock wave is generated by a contracting piston with finite initial velocity. For the initial shock motion, a perturbation method is used to determine the starting condition for the numerical calculation. Propagation of the shock wave and flow field properties are obtained and the transition of the non-self-similar motion of the shock wave into the self-similar one is presented. Good agreement between self-similar exponents determined from the variation of the shock strength and those calculated by Guderley is obtained.
Bain, R.J. . Dept. of Geology)
1993-03-01
Fluidized bed combustion of coal is considered one of the more promising clean coal technologies for the future. While much research has gone into the design and operation of FBC units, there is little concern for what characterizes a high quality sorbent and the source of such a sorbent. Carbonate rocks, limestone and dolomite, have been tested extensively as sorbents and primarily two rock characteristics appear to significantly control reactivity: composition and texture. Calcium carbonate is more reactive than magnesium carbonate where all other rock characteristics are the same. In considering texture, highest reactivity is measured for carbonate rocks which consist of homogeneous, euhedral crystals ranging in size from .05 to .2 mm and which possess uniform intercrystalline porosity. The most reactive material possesses both high calcium content, uniform microcrystalline texture and intercrystalline porosity, however, such material is not very abundant in nature and is not locally available to midcontinent facilities. Sucrosic dolomite, which possesses uniform microcrystalline texture and intercrystalline porosity has high rank reactivity. While this rock is quite common, it occurs as beds, generally less than twenty feet thick, interlayered with less reactive dolomite types. Therefore, without selective quarrying methods, production of sorbent with uniformly high reactivity will be impossible.
Zucker, Kenneth J; Bradley, Susan J; Owen-Anderson, Allison; Kibblewhite, Sarah J; Wood, Hayley; Singh, Devita; Choi, Kathryn
2012-01-01
This study provided a descriptive and quantitative comparative analysis of data from an assessment protocol for adolescents referred clinically for gender identity disorder (n = 192; 105 boys, 87 girls) or transvestic fetishism (n = 137, all boys). The protocol included information on demographics, behavior problems, and psychosexual measures. Gender identity disorder and transvestic fetishism youth had high rates of general behavior problems and poor peer relations. On the psychosexual measures, gender identity disorder patients had considerably greater cross-gender behavior and gender dysphoria than did transvestic fetishism youth and other control youth. Male gender identity disorder patients classified as having a nonhomosexual sexual orientation (in relation to birth sex) reported more indicators of transvestic fetishism than did male gender identity disorder patients classified as having a homosexual sexual orientation (in relation to birth sex). The percentage of transvestic fetishism youth and male gender identity disorder patients with a nonhomosexual sexual orientation self-reported similar degrees of behaviors pertaining to transvestic fetishism. Last, male and female gender identity disorder patients with a homosexual sexual orientation had more recalled cross-gender behavior during childhood and more concurrent cross-gender behavior and gender dysphoria than did patients with a nonhomosexual sexual orientation. The authors discuss the clinical utility of their assessment protocol. PMID:22390530
Broyles, D L; Nielsen, R G; Bussett, E M; Lu, W D; Mizrahi, I A; Nunnelly, P A; Ngo, T A; Noell, J; Christenson, R H; Kress, B C
1998-10-01
The performance characteristics of the Tandem-MP Ostase assay, a new microplate immunoassay for bone-specific alkaline phosphatase (bone ALP; EC 3.1.3.1) in human sera, are described. Bone ALP is bound to streptavidin-coated microwells by a single biotinylated anti-bone ALP monoclonal antibody. Antigen is detected by the addition of p-nitrophenyl phosphate. The assay is performed at room temperature in <90 min. Imprecision was 2.3-6.1% with a detection limit of 0.6 microg/L. Method comparison of bone ALP measurements with the Tandem-MP Ostase assay and the mass-based Tandem-R Ostase assay (n = 285) indicated regression statistics of Tandem-MP Ostase = 1.03 Tandem-R Ostase + 0.22 microg/L, S(y/x) = 4.0 microg/L, r = 0.97. Serum bone ALP values in apparently healthy men and in pre- and postmenopausal women were also similar between the two Ostase assay formats. Liver ALP reactivity determined using the slope and heat inactivation methods was similar in both Ostase assays. Liver ALP reactivity ranged from 3 microg/L (heat inactivation) to 6 microg/L (slope method) per 100 U/L of liver ALP activity, whereas bone ALP reactivity was 37 microg/L per 100 U/L of bone ALP activity, indicating a liver ALP relative reactivity of 8.1-16.2%. Similar results were obtained with the Alkphase-B bone ALP immunoassay. The Tandem-MP Ostase bone ALP assay demonstrated increased concentrations of serum bone ALP in conditions where bone metabolism is increased and showed a rapid, temporal decrease in serum bone ALP in Paget disease patients on bisphosphonate therapy. In conclusion, the Tandem-MP Ostase assay for serum bone ALP is a rapid, simple, robust nonisotopic alternative to the Tandem-R Ostase immunoradiometric assay that provides an accurate and sensitive assessment of bone turnover. PMID:9761247
Coxell, Adrian; King, Michael; Mezey, Gillian; Gordon, Dawn
1999-01-01
Objective To identify the lifetime prevalence of non-consensual sexual experiences in men, the relationship between such experiences as a child and as an adult, associated psychological and behavioural problems, and help received. Design Cross sectional survey. Setting England. Subjects 2474 men (mean age 46 years) attending one of 18 general practices. Main outcome measures Experiences of non-consensual and consensual sex before and after the age of 16 years—that is, as a child and adult respectively—psychological problems experienced for more than 2 weeks at any one time, use of alcohol (CAGE questionnaire), self harm, and help received. Results 2474 of 3142 men (79%) agreed to participate; 71/2468 (standardised rate 2.89%, 95% confidence interval 2.21% to 3.56%) reported non-consensual sexual experiences as adults, 128/2423 (5.35%, 4.39% to 6.31%) reported non-consensual sexual experiences as children, and 185/2406 (7.66%, 6.54% to 8.77%) reported consensual sexual experiences as children that are illegal under English law. Independent predictors of non-consensual sex as adults were reporting male sexual partners (odds ratio 6.0, 2.6 to 13.5), non-consensual sex in childhood (4.2, 2.1 to 8.6), age (0.98, 0.96 to 0.99), and sex of interviewer (2.0, 1.2 to 3.5). Non-consensual sexual experiences were associated with a greater prevalence of psychological problems, alcohol misuse, and self harm. These sexual experiences were also significant predictors of help received from mental health professionals. Conclusion Almost 3% of men in England report non-consensual sexual experiences as adults. Medical professionals need to be aware of the range of psychological difficulties in men who have had such experiences. They also need to be aware of the relationship between sexual experiences in childhood and adulthood in men. Key messagesAlmost 3% of men report non-consensual sexual experiences as adultsOver 5% of men report sexual abuse as childrenNon-consensual sexual