Feng, Xin; Ye, Xingyou; Park, Jun-Bom; Lu, Wenli; Morott, Joe; Beissner, Brad; Lian, Zhuoyang John; Pinto, Elanor; Bi, Vivian; Porter, Stu; Durig, Tom; Majumdar, Soumyajit; Repka, Michael A
2015-01-01
The recrystallization of an amorphous drug in a solid dispersion system could lead to a loss in the drug solubility and bioavailability. The primary objective of the current research was to use an improved kinetic model to evaluate the recrystallization kinetics of amorphous structures and to further understand the factors influencing the physical stability of amorphous solid dispersions. Amorphous solid dispersions of fenofibrate with different molecular weights of hydroxypropylcellulose, HPC (Klucel™ LF, EF, ELF) were prepared utilizing hot-melt extrusion technology. Differential scanning calorimetry was utilized to quantitatively analyze the extent of recrystallization in the samples stored at different temperatures and relative humidity (RH) conditions. The experimental data were fitted into the improved kinetics model of a modified Avrami equation to calculate the recrystallization rate constants. Klucel LF, the largest molecular weight among the HPCs used, demonstrated the greatest inhibition of fenofibrate recrystallization. Additionally, the recrystallization rate (k) decreased with increasing polymer content, however exponentially increased with higher temperature. Also k increased linearly rather than exponentially over the range of RH studied.
Holmes, R.D.
1985-01-01
Although it is mostly employed to estimate the amount of crystallization needed to form the observed members of a magmatic suite from a given parental magma, the Rayleigh distillation equation can also be used to quantitatively model igneous variation trends. On a simple x-y variation diagram there are four geometrically possible combinations of slope (+ or -) and curvature (up and down), but differentiation of the Rayleigh equation using the method of parametric equations shows that one of these four patterns is mathematically forbidden. However, this forbidden curvature is, in fact, observed in a number of simple comagmatic suites. This inadequacy in the simple Rayleigh equation was overcome by developing a physical model that takes into account the role of preexisting solid crystals in the magmatic fractionation process. These phenocrysts act as relatively inert particles that are concentrated into the cumulates that accrete at the crystallization interface along the chamber's walls. Moreover, the abundance of phenocrysts in the residual magma is progressively diluted by the remixing of fractionated melts that escape from this zone of dynamic crystallization. Using existing distribution coefficients, this model is able to elegantly explain the occurrence of forbidden curvature. Additionally, the model offers powerful insights into the origin of granitic textures and provides the key to interpreting the bulk line of descent (as distinct from the liquid line of descent).
NASA Astrophysics Data System (ADS)
Schipani, F.; Aldao, C. M.; Ponce, M. A.
2012-12-01
The capacitive behaviour of an intergranular double Schottky barrier in a polycrystalline semiconductor was evaluated. We found that the widely applied version of the Mott-Schottky equation can lead to significant errors. Even though we considered strong Fermi level pinning at the interface and no deep levels, the Mott-Schottky equation can be inadequate leading to huge errors due to voltage splitting at double Schottky barriers. Experiments carried out on ZnO varistors corroborated the main trends of our analysis.
On the validity of Avrami formalism in primary crystallization
NASA Astrophysics Data System (ADS)
Bruna, Pere; Crespo, Daniel; González-Cinca, Ricard; Pineda, Eloi
2006-09-01
Calorimetric data of primary crystallization is usually interpreted in the framework of the Kolmogorov [Dokl. Akad. Nauk SSSR 1, 355 (1937)], Johnson and Mehl [Trans. AIME 135, 416 (1939)], and Avrami [J. Chem. Phys. 7, 1103 (1939); 8, 212 (1940); 9, 177 (1941)] (KJMA) theory. However, while the KJMA theory assumes random nucleation and exhaustion of space by direct impingement, primary crystallization is usually driven by diffusion-controlled growth with soft impingement between the growing crystallites. This results in a stop of the growth before the space is fully crystallized and induces nonrandom nucleation. In this work, phase-field simulations are used to check the validity of different kinetic models for describing primary crystallization kinetics. The results show that KJMA theory provides a good approximation to the soft-impingement and nonrandom nucleation effects. Moreover, these effects are not responsible of the slowing down of the kinetics found experimentally in the primary crystallization of glasses.
Hypnotherapy and Female Sexual Inadequacy
Glick, Daniel
1972-01-01
Dr. Glick describes the use of hypnosis in the treatment of primary and secondary frigidity, dyspareunia and psychosomatic symptoms in female sexual inadequacy. He uses case histories to show the various techniques used and the results that can be expected. PMID:20468741
A texture-component Avrami model for predicting recrystallization textures, kinetics and grain size
NASA Astrophysics Data System (ADS)
Raabe, Dierk
2007-03-01
The study presents an analytical model for predicting crystallographic textures and the final grain size during primary static recrystallization of metals using texture components. The kinetics is formulated as a matrix variant of the Johnson-Mehl-Avrami-Kolmogorov equation. The matrix form is required since the kinetic and crystallographic evolution of the microstructure is described in terms of a limited set of growing (recrystallizing) and swept (deformed) texture components. The number of components required (5-10) defines the order of the matrix since the kinetic coupling occurs between all recrystallizing and all deformed components. Each such couple is characterized by corresponding values for the nucleation energy and grain boundary mobility. The values of these parameters can be obtained by analytical or numerical coarse graining according to a renormalization scheme which replaces many individual grains which grow via recrystallization in a deformed texture component by a single equivalent recrystallization texture component or by fitting to experimental data. Each deformed component is further characterized by an average stored deformation energy. Each element of the kinetic matrix, reflecting one of the possible couplings between a deformed and a recrystallizing texture component, is then derived in each time step by a set of two differential equations. The first equation describes the thermally activated nucleation and growth processes for the expanded (free) volume for a particular couple of a deformed and a recrystallizing texture component and the second equation is used for calculating the constrained (real) volume for that couple which corrects the free volume for those portions of the deformation component which were already swept. The new method is particularly developed for the fast and physically based process simulation of recrystallization textures with respect to processing. The present paper introduces the method and applies it to the
Order and randomness in Kolmogorov-Johnson-Mehl-Avrami-type phase transitions
NASA Astrophysics Data System (ADS)
Fanfoni, M.; Persichetti, L.; Tomellini, M.
2012-09-01
The distribution of points on a 2D domain influences the kinetics of its coverage when a growth law is attached at each point. This implies that the kinetics of space filling can be adopted as a descriptor of the degree of order of the initial point distribution. In this paper, the degree of order of an initial array of points has been changed following two paths: (i) from a regular square lattice, through increasing displacement assigned to each point, towards Poissonian disorder; (ii) from a Poissonian distribution, by introducing a hard core potential with increasing correlation lengths, towards a more ordered lattice. A linear growth law has been attached to the points of the initial array and the kinetics X(Xe), where Xe is the extended coverage as defined in the Kolmogorov-Johnson-Mehl-Avrami model, has been monitored. The quantitative analysis has been performed by fitting the kinetics to an equation which we propose for the first time and which has proved to be, in fact, highly suitable for the purpose. The results demonstrate that the gross of variation from order to disorder is obtained for point displacements, u, of the order of a, the latter being the constant of a square lattice. Vice versa, the introduction of a correlation distance in a random distribution provokes at most an order limited to the first neighbors and no real order can ever be reached. Others descriptors have been investigated, all confirming our results. We also developed an analytical description based on the use of the f-functions, as have been defined by Van Kampen, up to the second order terms. Such a description has been shown to work well for u/a < 1 within an interval ΔXe which depends on the ɛ value.
NASA Astrophysics Data System (ADS)
Tomellini, Massimo
2017-03-01
On the basis of the Kolmogorov-Johnson-Mehl-Avrami (KJMA) method for space tessellation the kinetics of Voronoi cell filling, by central grain growth, has been studied as a function of the cell size. This is done by solving an integral equation for which a class of solutions is obtained in closed form, where the cell-size probability density is the Gamma distribution function. The computation gives the time evolution of the mean grain size, as a function of cell volume, which is further employed for describing the grain-size probability density function. The present approach is applied to determine, analytically, the exact grain-size distribution function in 1D and the size distributions in 2D and 3D through approximation.
Representing Model Inadequacy in Combustion Kinetics
NASA Astrophysics Data System (ADS)
Morrison, Rebecca E.; Moser, Robert D.
2014-11-01
An accurate description of the chemical processes involved in the oxidation of hydrocarbons may include hundreds of reactions and thirty or more chemical species. Kinetics models of these chemical mechanisms are often embedded in a fluid dynamics solver to represent combustion. Because the computational cost of such detailed mechanisms is so high, it is common practice to use drastically reduced mechanisms. But, this introduces modeling errors which may render the model inadequate. In this talk, we present a formulation of the model inadequacy in reduced models of hydrogen-methane combustion. Our goal is to account for the discrepancy between the high-fidelity model and its reduced version by incorporating an additive, linear, probabilistic inadequacy model. In effect, it is a random matrix, whose entries are characterized by probability distributions and which displays interesting properties due to conservation constraints. The distributions are calibrated via Bayesian inference using a hierarchical modeling scheme and high-dimensional MCMC. We apply this technique to a stand-alone reaction and also incorporate it within a one-dimensional laminar flame problem.
Pas, Steven J; Dargusch, Matthew S; MacFarlane, Douglas R
2011-07-07
The properties of ionic liquids give rise to applications in diverse technology areas including mechanical engineering, mining, aerospace and defence. The arbitrary physical property that defines an ionic liquid is a melting point below 100 °C, and as such, an understanding of crystallisation phenomena is extremely important. This is the first report dealing with the mechanism of crystallisation in ionic liquids. Assuming crystallisation of the ionic liquids is a thermal or mass diffusion-controlled process, the values of the isothermal Avrami exponent obtained from three different ionic liquids with three different anions and cations all indicate that growth occurs with a decreasing nucleation rate (n=1.8-2.2). For one of the ionic liquids it was possible to avoid crystallisation by fast cooling and then observe a devitrification upon heating through the glass transition. The isothermal Avrami exponent of devitrification suggested growth with an increasing nucleating rate (n=4.1), compared to a decreasing nucleation rate when crystallisation occurs on cooling from the melt (n=2.0). Two non-isothermal methods were employed to determine the Avrami exponent of devitrification. Both non-isothermal Avrami exponents were in agreement with the isothermal case (n=4.0-4.15). The applicability of JMAK theory suggests that the nucleation event in the ionic liquids selected is a random stochastic process in the volume of the material. Agreement between the isothermal and non-isothermal techniques for determining the Avrami exponent of devitrification suggests that the pre-exponential factor and the activation energy are independent of thermal history. The heating rate dependence of the glass transition enabled the calculation of the fragility index, which suggests that the ionic liquid is a "strong" glass former. This suggests that the temperature dependence of the rate constant could be close to Arrhenius, as assumed by JMAK theory. More generally, therefore, it can be
Vitamin D inadequacy in pregnancy: biology, outcomes, and interventions
USDA-ARS?s Scientific Manuscript database
A high prevalence of maternal vitamin D inadequacy during pregnancy and at delivery has been demonstrated in various ethnic populations living at different latitudes. Because placental transfer of 25(OH)D is the major source of vitamin D to the developing human fetus, there is growing concern about ...
Nutrient inadequacy among nutritionally vulnerable populations in the US
USDA-ARS?s Scientific Manuscript database
Objective: To estimate the prevalence of inadequacy of selected nutrients among participants in the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC); participants in the Supplemental Nutrition Assistance Program (SNAP); and those with low/very low food security status. ...
An Inadequacy Formulation for an Uncertain Flamelet Model
NASA Astrophysics Data System (ADS)
Sondak, David; Oliver, Todd; Simmons, Chris; Moser, Robert
2016-11-01
We report progress on the development of an uncertain flamelet library for use in non-premixed turbulent combustion. A stochastic inadequacy operator is generalized from previous work and is now used to incorporate uncertainties in chemical reaction mechanisms in a flamelet model. The original form of the inadequacy operator was designed to enforce positivity of chemical species concentrations and conservation of species while representing inadequacies in reduced chemical mechanisms. As a first step towards generalization, we are exploring temperature dependent modifications to the inadequacy operator. The temperature dependence helps ensure that the operator is inactive in the absence of chemical reactions and becomes active only after ignition. A Bayesian inverse problem is used to calibrate the stochastic operator on a hydrogen-oxygen zero-dimensional reactor and to infer model parameters, and their uncertainties, from data obtained via a detailed chemical mechanism. The inferred model parameters are then propagated through a laminar, non-premixed, counterflow hydrogen-oxygen flame. Temperature and species profiles at various scalar dissipation rates are compared to those predicted from a five-reaction reduced model and the detailed model.
Dill, Eric D.; Folmer, Jacob C.W.; Martin, James D.
2013-12-05
A series of simulations was performed to enable interpretation of the material and physical significance of the parameters defined in the Kolmogorov, Johnson and Mehl, and Avrami (KJMA) rate expression commonly used to describe phase boundary controlled reactions of condensed matter. The parameters k, n, and t_{0} are shown to be highly correlated, which if unaccounted for seriously challenge mechanistic interpretation. It is demonstrated that rate measurements exhibit an intrinsic uncertainty without precise knowledge of the location and orientation of nucleation with respect to the free volume into which it grows. More significantly, it is demonstrated that the KJMA rate constant k is highly dependent on sample size. However, under the simulated conditions of slow nucleation relative to crystal growth, sample volume and sample anisotropy correction affords a means to eliminate the experimental condition dependence of the KJMA rate constant, k, producing the material-specific parameter, the velocity of the phase boundary, v_{pb}.
Representing Model Inadequacy in Combustion Mechanisms of Laminar Flames
NASA Astrophysics Data System (ADS)
Morrison, Rebecca; Moser, Robert; Oliver, Todd
2015-11-01
An accurate description of the chemical processes involved in the oxidation of hydrocarbons may include hundreds of reactions and thirty or more chemical species. Kinetics models of these chemical mechanisms are often embedded in a fluid dynamics solver to represent combustion. Because the computational cost of such detailed mechanisms is so high, it is common practice to use drastically reduced mechanisms. But, this introduces modeling errors which may render the model inadequate. In this talk, we present a formulation of the model inadequacy in reduced models of combustion mechanisms. Our goal is to account for the discrepancy between the detailed model and its reduced version by incorporating an additive, linear, probabilistic inadequacy model. In effect, it is a random matrix, whose entries are characterized by probability distributions and which displays interesting properties due to conservation constraints. In particular, we investigate how the inclusion of the random matrix affects the prediction of flame speed in a one-dimensional hydrogen laminar flame.
NASA Astrophysics Data System (ADS)
Ramos, Raphael A.; Rikvold, Per Arne; Novotny, M. A.
1999-04-01
The Kolmogorov-Johnson-Mehl-Avrami (KJMA) theory for the time evolution of the order parameter in systems undergoing first-order phase transformations has been extended by Sekimoto to the level of two-point correlation functions. Here, this extended KJMA theory is applied to a kinetic Ising lattice-gas model, in which the elementary kinetic processes act on microscopic length and time scales. The theoretical framework is used to analyze data from extensive Monte Carlo simulations. The theory is inherently a mesoscopic continuum picture, and in principle it requires a large separation between the microscopic scales and the mesoscopic scales characteristic of the evolving two-phase structure. Nevertheless, we find excellent quantitative agreement with the simulations in a large parameter regime, extending remarkably far towards strong fields (large supersaturations) and correspondingly small nucleation barriers. The original KJMA theory permits direct measurement of the order parameter in the metastable phase, and using the extension to correlation functions one can also perform separate measurements of the nucleation rate and the average velocity of the convoluted interface between the metastable and stable phase regions. The values obtained for all three quantities are verified by other theoretical and computational methods. As these quantities are often difficult to measure directly during a process of phase transformation, data analysis using the extended KJMA theory may provide a useful experimental alternative.
Model inadequacy and mistaken inferences of trait-dependent speciation.
Rabosky, Daniel L; Goldberg, Emma E
2015-03-01
Species richness varies widely across the tree of life, and there is great interest in identifying ecological, geographic, and other factors that affect rates of species proliferation. Recent methods for explicitly modeling the relationships among character states, speciation rates, and extinction rates on phylogenetic trees- BiSSE, QuaSSE, GeoSSE, and related models-have been widely used to test hypotheses about character state-dependent diversification rates. Here, we document the disconcerting ease with which neutral traits are inferred to have statistically significant associations with speciation rate. We first demonstrate this unfortunate effect for a known model assumption violation: shifts in speciation rate associated with a character not included in the model. We further show that for many empirical phylogenies, characters simulated in the absence of state-dependent diversification exhibit an even higher Type I error rate, indicating that the method is susceptible to additional, unknown model inadequacies. For traits that evolve slowly, the root cause appears to be a statistical framework that does not require replicated shifts in character state and diversification. However, spurious associations between character state and speciation rate arise even for traits that lack phylogenetic signal, suggesting that phylogenetic pseudoreplication alone cannot fully explain the problem. The surprising severity of this phenomenon suggests that many trait-diversification relationships reported in the literature may not be real. More generally, we highlight the need for diagnosing and understanding the consequences of model inadequacy in phylogenetic comparative methods.
40 CFR 52.32 - Sanctions following findings of SIP inadequacy.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 40 Protection of Environment 3 2012-07-01 2012-07-01 false Sanctions following findings of SIP inadequacy. 52.32 Section 52.32 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... following findings of SIP inadequacy. For purposes of the SIP revisions required by § 51.120, EPA may make...
40 CFR 52.32 - Sanctions following findings of SIP inadequacy.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 40 Protection of Environment 3 2011-07-01 2011-07-01 false Sanctions following findings of SIP inadequacy. 52.32 Section 52.32 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... following findings of SIP inadequacy. For purposes of the SIP revisions required by § 51.120, EPA may make...
40 CFR 52.32 - Sanctions following findings of SIP inadequacy.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 40 Protection of Environment 3 2014-07-01 2014-07-01 false Sanctions following findings of SIP inadequacy. 52.32 Section 52.32 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... following findings of SIP inadequacy. For purposes of the SIP revisions required by § 51.120, EPA may make...
40 CFR 52.32 - Sanctions following findings of SIP inadequacy.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 40 Protection of Environment 3 2013-07-01 2013-07-01 false Sanctions following findings of SIP inadequacy. 52.32 Section 52.32 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... following findings of SIP inadequacy. For purposes of the SIP revisions required by § 51.120, EPA may make...
40 CFR 52.32 - Sanctions following findings of SIP inadequacy.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 40 Protection of Environment 3 2010-07-01 2010-07-01 false Sanctions following findings of SIP inadequacy. 52.32 Section 52.32 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) AIR... following findings of SIP inadequacy. For purposes of the SIP revisions required by § 51.120, EPA may make...
Vitamin E Inadequacy in Humans: Causes and Consequences12
Traber, Maret G.
2014-01-01
It is estimated that >90% of Americans do not consume sufficient dietary vitamin E, as α-tocopherol, to meet estimated average requirements. What are the adverse consequences of inadequate dietary α-tocopherol intakes? This review discusses health aspects where inadequate vitamin E status is detrimental and additional vitamin E has reversed the symptoms. In general, plasma α-tocopherol concentrations <12 μmol/L are associated with increased infection, anemia, stunting of growth, and poor outcomes during pregnancy for both the infant and the mother. When low dietary amounts of α-tocopherol are consumed, tissue α-tocopherol needs exceed amounts available, leading to increased damage to target tissues. Seemingly, adequacy of human vitamin E status cannot be assessed from circulating α-tocopherol concentrations, but inadequacy can be determined from “low” values. Circulating α-tocopherol concentrations are very difficult to interpret because, as a person ages, plasma lipid concentrations also increase and these elevations in lipids increase the plasma carriers for α-tocopherol, leading to higher circulating α-tocopherol concentrations. However, abnormal lipoprotein metabolism does not necessarily increase α-tocopherol delivery to tissues. Additional biomarkers of inadequate vitamin E status are needed. Urinary excretion of the vitamin E metabolite α-carboxy-ethyl-hydroxychromanol may fulfill this biomarker role, but it has not been widely studied with regard to vitamin E status in humans or with regard to health benefits. This review evaluated the information available on the adverse consequences of inadequate α-tocopherol status and provides suggestions for avenues for research. PMID:25469382
Inadequacy of in-school support for diabetic children.
Lewis, Dalila W; Powers, Patricia A; Goodenough, Mary F; Poth, Merrily A
2003-01-01
The level of blood glucose control needed to minimize complications in children with diabetes requires frequent blood sugar monitoring and appropriate responses to the information obtained. It is our impression that optimal support for good control is not available in all of the schools our patients attend. The objective of this study was to identify and quantify barriers to good control of diabetes in the school setting, and then use this information to target interventions to improve in-school support for children with diabetes. Two questionnaires were designed based on recommendations of the American Diabetes Association for appropriate in-school support for children with diabetes. Parental perception of in-school resources was addressed in one questionnaire. Forty-seven parents of children with diabetes in our clinic were surveyed. The second questionnaire was mailed to 222 randomly selected schools in our area inquiring about the in-school support available to children with diabetes and the types of educational materials that would be useful for school personnel. Thirty percent of the parents of children with diabetes indicated that the in-school support of their child was insufficient. Sixty-five of the 222 schools surveyed responded. The responses were variable and demonstrated inconsistency and, in some cases, inadequacy of support. A major deficiency noted in 13% of schools was lack of on-site personnel trained in diabetes management skills. From the schools' perspective, however, 50% of schools reported lack of parental communication. The care available for the child with diabetes is highly variable among schools. Targeted educational materials for both school personnel and parents would be useful to improve support for these children.
East, Patricia L.; Barber, Jennifer S.
2015-01-01
On the basis of theories of maternal identity development, role conflict, and childbearing motivation, the authors tested whether high educational aspirations among pregnant adolescents are related to the unwantedness of the pregnancy and whether pregnancy unwantedness leads to subsequent parenting stress and inadequacy. Longitudinal data from 100 first-time-pregnant, unmarried Latina adolescents (M age = 17.3 years) were analyzed. Results from structural equation path modeling confirmed these associations, with strong educational ambitions related to greater unwantedness of the pregnancy, which led to feeling trapped by parenting at 6 months postpartum, which in turn was related to unaffectionate parenting and feeling inadequate in mothering at 1 year postpartum. The potential long-term negative consequences of high educational aspirations for pregnant adolescents’ adjustment to parenting are discussed. PMID:25641985
Inadequacy of single-impulse transfers for path constrained rendezvous
NASA Technical Reports Server (NTRS)
Stern, S. A.; Soileau, K. M.
1987-01-01
The use of single-impulse techniques to maneuver from point to point about a large space structure (LSS) with an arbitrary geometrical configuration and spin is examined. Particular consideration is given to transfers with both endpoints on the forbidden zone surface. Clohessy-Wiltshire equations of relative motion are employed to solve path constrained rendezvous problems. External and internal transfers between arbitrary points are analyzed in terms of tangential departure and arrival conditions. It is observed that single-impulse techniques are inadequate for transferring about the exterior of any LSS; however, single-impulse transfers are applicable for transfers in the interior of LSSs. It is concluded that single-impulse transducers are not applicable for path constrained rendezvous guidance.
Suberviola Cañas, B; Jáuregui, R; Ballesteros, M Á; Leizaola, O; González-Castro, A; Castellanos-Ortega, Á
2015-11-01
To assess how antibiotic administration delay and inadequacy influence survival in septic shock patients. A prospective, observational cohort study was carried out between September 2005 and September 2010. Patients admitted to the ICU of a third level hospital. A total of 342 septic shock patients None The time to antibiotic administration (difference between septic shock presentation and first administered dose of antibiotic) and its adequacy (in vitro susceptibility testing of isolated pathogens) were determined. ICU and hospital mortality were 26.4% and 33.5%, respectively. The median delay to administration of the first antibiotic dose was 1.7h. Deceased patients received antibiotics significantly later than survivors (1.3±14.5h vs. 5.8±18.02h; P=.001). Percentage drug inadequacy was 12%. Those patients who received inadequate antibiotics had significantly higher mortality rates (33.8% vs. 51.2%; P=.03). The coexistence of treatment delay and inadequacy was associated to lower survival rates. Both antibiotic administration delay and inadequacy exert deleterious effects upon the survival of septic shock patients, independently of their characteristics or severity. Copyright © 2015 Elsevier España, S.L.U. and SEMICYUC. All rights reserved.
The Inadequacy of Academic Environment Contributes to Inadequate Teaching and Learning Phenomena
ERIC Educational Resources Information Center
Quasim, Shahla; Arif, Muhammad Shahbaz
2014-01-01
This study aims at the inadequacy of academic environment as an indicator contributing to the inadequate teaching and learning situation in Pakistan. The main focus is to look into the low proficiency of students in the subject of English at secondary school level. A comprehensive questionnaire was designed from the literature concerned and The…
Anemia in postmenopausal women: dietary inadequacy or non-dietary factors
USDA-ARS?s Scientific Manuscript database
Postmenopausal women are disproportionately affected by anemia, and the prevalence in females > 65 years of age in the United States is approximately 10%. The manifestation of anemia in older populations is associated with dietary inadequacy, blood loss, genetics, alterations in bioavailability, ren...
The Inadequacy of Academic Environment Contributes to Inadequate Teaching and Learning Phenomena
ERIC Educational Resources Information Center
Quasim, Shahla; Arif, Muhammad Shahbaz
2014-01-01
This study aims at the inadequacy of academic environment as an indicator contributing to the inadequate teaching and learning situation in Pakistan. The main focus is to look into the low proficiency of students in the subject of English at secondary school level. A comprehensive questionnaire was designed from the literature concerned and The…
NASA Astrophysics Data System (ADS)
Kautz, Elizabeth J.
Microstructure and chemistry of zirconium alloys have a major influence on material performance, including mechanical properties and corrosion resistance. Therefore, it is essential to thoroughly understand processing required to obtain desired microstructures for application in commercial nuclear reactors. Zirconium-niobium alloys are of particular interest for commercial nuclear applications (e.g., in boiling water reactors, pressurized water reactors, Canadian deuterium uranium reactors) due to increased corrosion resistance in aqueous environments over other zirconium alloys. Heat treatments of zirconium-niobium alloys affect overall microstructure, precipitate distributions and size, and ultimately determine material performance. Phase transformations in zirconium-niobium alloys were modeled for a range of niobium concentrations and heat treatment conditions, by conducting controlled experiments. Heat-flux differential scanning calorimetry was performed and data was collected and analyzed for zirconium-niobium alloys with niobium content ranging from 0.6-3.0 weight percent. Continuous cooling transformation diagrams were constructed for slow cooling rate conditions (9-34°C/minute) based on calorimetry test results. A standard operating procedure for performing these calorimetry tests and corresponding data analysis technique was developed specifically to study the zirconium-niobium material system. A mathematical model was developed utilizing the Kolmogorov-Johnson-Mehl-Avrami theory that accurately describes phase transformations upon continuous cooling in zirconium-niobium binary alloys. This model relates fraction of phase transformed to kinetic parameters that were calculated from experimental test results in order to model the phase transformation for various cooling rates from 10-40°C/minute.
Huijgen, Nicole A.; Laven, Joop S. E.; Labee, Chantal T.; Louwers, Yvonne V.; Willemsen, Sten P.; Steegers-Theunissen, Régine P. M.
2015-01-01
Background The composition of the diet is of increasing importance for the development and maturation of the ovarian follicles. In Polycystic Ovary Syndrome (PCOS) healthy dietary interventions improve the clinical spectrum. We hypothesized that dieting and diet inadequacy in the reproductive life course is associated with impaired programming of ovarian follicles and contributes to the severity of the PCOS phenotype. Methods and Findings To determine associations between the use of a self-initiated diet and diet inadequacy and the severity of the PCOS phenotype, we performed an explorative nested case control study embedded in a periconception cohort of 1,251 patients visiting the preconception outpatient clinic. 218 patients with PCOS and 799 subfertile controls were selected from the cohort and self-administered questionnaires, anthropometric measurements and blood samples were obtained. The Preconception Dietary Risk Score (PDR score), based on the Dutch dietary guidelines, was used to determine diet inadequacy in all women. The PDR score was negatively associated to cobalamin, serum and red blood cell folate and positively to tHcy. PCOS patients (19.9%), in particular the hyperandrogenic (HA) phenotype (22.5%) reported more often the use of a self-initiated diet than controls (13.1%; p = 0.023). The use of an inadequate diet was also significantly higher in PCOS than in controls (PDR score 3.7 vs 3.5; p = 0.017) and every point increase was associated with a more than 1.3 fold higher risk of the HA phenotype (adjusted OR 1.351, 95% CI 1.09–1.68). Diet inadequacy was independently associated with the anti-Müllerian Hormone (AMH) concentration (β 0.084; p = 0.044; 95% CI 0.002 to 0.165) and free androgen index (β 0.128; p = 0.013; 95% CI 0.028 to 0.229) in PCOS patients. Conclusions The use of a self-initiated diet and diet inadequacy is associated with PCOS, in particular with the severe HA phenotype. This novel finding substantiated by the association
Thiamin inadequacy in infants: lack of evidence of amprolium in egg yolk.
Thornber, E J; Elliott, L E; Kerr, D; Marriott, J M; Massera, F C
1983-02-01
This study investigated the hypothesis that the consumption of egg yolks might lead to thiamin inadequacy in infants because of the possible contamination of the egg yolks with amprolium. Earlier workers showed that the presence of amprolium in the diet inhibits the absorption of thiamin. Amprolium is added to some poultry feeds to control coccidiosis: it is readily incorporated in the egg yolk and egg yolk is one of the solid foods offered to infants at weaning. We found that under current commercial poultry feeding practices in WA it is extremely unlikely that any amprolium would be present in commercial eggs or poultry. Amprolium was undetectable in eggs purchased at several retail outlets. Thus there is no evidence that consumption of egg yolk contributes to thiamin inadequacy in infants.
Prevalence and predictors of vitamin D inadequacy amongst Lebanese osteoporotic women.
Gannagé-Yared, Marie-Hélène; Maalouf, Ghassan; Khalife, Simon; Challita, Samir; Yaghi, Yasser; Ziade, Nelly; Chalfoun, Amal; Norquist, Josephine; Chandler, Julie
2009-02-01
In Middle-Eastern countries, more particularly in Lebanon, the incidence of vitamin D deficiency has been found to be surprisingly high in schoolchildren and young individuals. However, the prevalence and risk factors for vitamin D inadequacy amongst Lebanese osteoporotic women seeking medical health care has never been studied. We analysed vitamin D-inadequacy risk factors among the 251 Lebanese postmenopausal osteoporotic women (from both Muslim and Christian communities) who participated in a vitamin D international epidemiological study. Vitamin D inadequacy prevalence (25-hydroxyvitamin D (25(OH)D) , 30 ng/ml) was 84.9%. 25(OH)D was negatively correlated with BMI (r 20.41; P<0.001) and positively correlated with educational level (r 0.37; P<0.001) and self-reported general health (r 0.17; P<0.01). No significant correlation was found with age and no seasonal variation was observed. There was no significant correlation between 25(OH)D and sun exposure index or vitamin D-rich food consumption. However, 25(OH)D strongly correlated with vitamin D supplement intake (r 0.48; P<0.0001). Muslim community participants had lower 25(OH)D levels compared with their Christian counterparts (P<0.001). They also had higher BMI, lower educational level and vitamin D supplement consumption and followed more frequently a dress code covering the arms (P<0.0001 for all variables). In a multivariate model, in Muslims, inadequate vitamin D supplements and a dress code covering the arms are the independent predictors of 25(OH)D inadequacy (P<0.001 for both variables). However, in Christians, the predictors are inadequate vitamin D supplements, high BMI and low educational level (P<0.001; P=002 and P=0.02 respectively). There is an urgent need to increase vitamin D supplement use in Middle-Eastern osteoporotic women, more particularly in those from the Muslim community.
Risk of nutrient inadequacies in elite Canadian athletes with spinal cord injury.
Krempien, Jennifer L; Barr, Susan I
2011-10-01
Energy intakes of adults with spinal cord injury (SCI) have been reported to be relatively low, with many micronutrients below recommended amounts, but little is known about the diets of athletes with SCI. The purpose of this cross-sectional, observational study was to assess energy intakes and estimate the prevalence of dietary inadequacy in a sample of elite Canadian athletes with SCI (n = 32). Three-day self-reported food diaries completed at home and training camp were analyzed for energy (kcal), macronutrients, vitamins, and minerals and compared with the dietary reference intakes (DRIs). The prevalence of nutrient inadequacy was estimated by the proportion of athletes with mean intakes below the estimated average requirement (EAR). Energy intakes were 2,156 ± 431 kcal for men and 1,991 ± 510 kcal for women. Macronutrient intakes were within the acceptable macronutrient distribution ranges. While at training camp, >25% of men had intakes below the EAR for calcium, magnesium, zinc, riboflavin, folate, vitamin B12, and vitamin D. Thiamin, riboflavin, calcium, and vitamin D intakes were higher at home than training camp. Over 25% of women had intakes below the EAR for calcium, magnesium, folate, and vitamin D, with no significant differences in mean intakes between home and training camp. Vitamin/mineral supplement use significantly increased men's intakes of most nutrients but did not affect prevalence of inadequacy. Women's intakes did not change significantly with vitamin/mineral supplementation. These results demonstrate that athletes with SCI are at risk for several nutrient inadequacies relative to the DRIs.
2007-11-02
ABSTRACT This thesis examines the current inadequacy of small arms training for all military occupational specialties ( MOSs ) in the...to facilitate advanced, short-range, CQC like marksmanship training that will allow soldiers of all MOSs to dominate their 100 meters. Introduce Small...Member Dennis L . Dolan, Ph.D. , Member LTC Tony D. Baker, M.S. Accepted this 17th day of June 2005 by: , Director
Towards Model Inadequacy Representations for Flamelet-Based RANS Combustion Simulations
NASA Astrophysics Data System (ADS)
Oliver, Todd; Lee, M. K.; Sondak, David; Simmons, Chris; Moser, Robert
2016-11-01
Flamelet-based RANS simulations are commonly used in combustion engineering. In such simulations, chemical reactions are represented by a "flamelet-library" of laminar diffusion flame solutions generated with some chemical mechanism, and turbulence is represented using typical eddy-viscosity-based RANS closures. Modeling errors are introduced through both of these models as well as their interaction. In this work, we formulate and apply physics-based stochastic model inadequacy representations to capture the effects of possible modeling errors, allowing their impact on quantities of interest to be estimated. Specifically, the uncertainty introduced by inadequacy of the chemical mechanism is represented using a recently developed stochastic operator approach, which is extended to the diffusion flame here, leading to a stochastic diffusion flame library. A Karhunen-Loeve decomposition applied to these random fields enables low-dimensional representation of this uncertainty. A stochastic extension of typical eddy-viscosity-based RANS models is developed to represent inadequacy in the turbulence closures. The full stochastic model is demonstrated on simulations of a planar jet flame.
ter Borg, Sovianne; Verlaan, Sjors; Hemsworth, Jaimie; Mijnarends, Donja M; Schols, Jos M G A; Luiking, Yvette C; de Groot, Lisette C P G M
2015-04-28
Micronutrient deficiencies and low dietary intakes among community-dwelling older adults are associated with functional decline, frailty and difficulties with independent living. As such, studies that seek to understand the types and magnitude of potential dietary inadequacies might be beneficial for guiding future interventions. We carried out a systematic review following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. Observational cohort and longitudinal studies presenting the habitual dietary intakes of older adults (≥65 years) were included. Sex-specific mean (and standard deviation) habitual micronutrient intakes were extracted from each article to calculate the percentage of older people who were at risk for inadequate micronutrient intakes using the estimated average requirement (EAR) cut-point method. The percentage at risk for inadequate micronutrient intakes from habitual dietary intakes was calculated for twenty micronutrients. A total of thirty-seven articles were included in the pooled systematic analysis. Of the twenty nutrients analysed, six were considered a possible public health concern: vitamin D, thiamin, riboflavin, Ca, Mg and Se. The extent to which these apparent inadequacies are relevant depends on dynamic factors, including absorption and utilisation, vitamin and mineral supplement use, dietary assessment methods and the selection of the reference value. In light of these considerations, the present review provides insight into the type and magnitude of vitamin and mineral inadequacies.
Zhao, Wenzhi; Yu, Kai; Tan, Shengjie; Zheng, Yingdong; Zhao, Ai; Wang, Peiyu; Zhang, Yumei
2017-05-12
Micronutrient malnutrition affects the well-being of both adults and children. Dietary diversity score (DDS) is a useful evaluation index with a relatively well-developed guideline by FAO. It's meaningful to assess and predict inadequate micronutrient intakes using DDS in Chinese children, after ruling out the risk of obesity coming with more dietary diversity. Data for evaluation were extracted from the Nutrition Study of Preschool Children and School Children, which is a cross-sectional study covering 8 cities of China, including 1694 children in kindergartens and primary schools. This study applied DDS to Chinese children to test the validity for micronutrient inadequacy, and then explored the relationship between dietary diversity and obesity. It reveals that dietary diversity varied with age and place of residence; the older ones and the ones living in rural areas tend to have poorer dietary diversity. Another discovery is that DDS is positively correlated with indicators of micronutrient adequacy, with a score of 6-8 indicating the lowest risk of micronutrient inadequacy in different groups of children. In our study population, dietary diversity is not related with obesity. Dietary diversity score is a valid indicator to evaluate micronutrient inadequacy in Chinese children, though there is still room for improvement of the method. Besides, the relationship between increase of dietary diversity and risk of obesity should be treated circumspectly.
2013-01-01
Objective The prevalence of smoking in Aboriginal Canadians is higher than non-Aboriginal Canadians, a behavior that also tends to alter dietary patterns. Compared with the general Canadian population, maternal smoking rates are almost twice as high. The aim of this study was to compare dietary adequacy of Inuvialuit women of childbearing age comparing smokers versus non-smokers. Research methods & procedures A cross-sectional study, where participants completed a culturally specific quantitative food frequency questionnaire. Non-parametric analysis was used to compare mean nutrient intake, dietary inadequacy and differences in nutrient density among smokers and non-smokers. Multiple logistic regression analyses were performed for key nutrients inadequacy and smoking status. Data was collected from three communities in the Beaufort Delta region of the Northwest Territories, Canada from randomly selected Inuvialuit women of childbearing age (19-44 years). Results Of 92 participants, 75% reported being smokers. There were no significant differences in age, BMI, marital status, education, number of people in household working and/or number of self employed, and physical activity between smokers and non-smokers. Non-parametric analysis showed no differences in nutrient intake between smokers and non-smokers. Logistic regression however revealed there was a positive association between smoking and inadequacies of vitamin C (OR = 2.91, 95% CI, 1.17-5.25), iron (OR = 3.16, 95% CI, 1.27-5.90), and zinc (OR = 2.78, 95% CI, 1.12-4.94). A high percentage of women (>60%), regardless of smoking status, did not meet the dietary recommendations for fiber, vitamin D, E and potassium. Conclusions This study provides evidence of inadequate dietary intake among Inuvialuit of childbearing age regardless of smoking behavior. PMID:23433392
Inadequacy of vitamins and minerals among high-school pupils in Ouarzazate, Morocco.
Anzid, Karim; Baali, Abdellatif; Vimard, Patrice; Levy-Desroches, Susan; Cherkaoui, Mohamed; López, Pilar Montero
2014-08-01
To assess micronutrient intakes and the prevalence of inadequacy in a sample of high-school pupils in Ouarzazate, Morocco. Food records were compiled over three non-consecutive days by pre-trained pupils. Micronutrient intakes were estimated using the DIAL software, adapted to include foods commonly eaten in Morocco. The prevalence of inadequacy was estimated by the proportion of individuals with intakes below the Estimated Average Requirement (EAR) for vitamins B12, A and K, thiamin, riboflavin, niacin, pyridoxine, folate, ascorbic acid, iodine, Ca, Mg and P; below the Adequate Intake (AI) level for pantothenic acid, biotin, Na and K; and using the probability approach for Fe. Data were adjusted for intra-individual variation with exclusion of under-reporters. Ouarzazate, a semi-urban region situated on the southern slopes of the High Atlas with little industrial development but an important tourism sector. A self-selected sample of 312 pupils aged 15-19 years from the five public high schools. After exclusion of under-reporters, 293 remained for analysis. The highest proportions of below-EAR/AI intakes were seen for pantothenic acid (girls 85·1 %, boys 78·0 %), biotin (boys 83·1 %, girls 79·4 %), thiamin (boys 66·9 %), folate (girls 93·1 %, boys 74·6 %), iodine (boys 94·9 %, girls 88·0 %) and Ca (girls 83·4 %, boys 74·6 %). Na intake was generally in excess whereas K intake was below the AI level. In general, girls had better-quality diets than boys, who appeared to consume more 'empty calories'. Our findings suggest that in this population of Moroccan adolescents, nutritional intervention and educational strategies are needed to promote healthy eating habits and correct micronutrient inadequacies. To provide reliable and precise estimates of nutrient intakes, an update of Moroccan food composition databases is urgently needed. We recommend that national authorities address these issues.
Hwalla, Nahla; Al Dhaheri, Ayesha Salem; Radwan, Hadia; Alfawaz, Hanan Abdullah; Fouda, Mona A.; Al-Daghri, Nasser Mohammed; Zaghloul, Sahar; Blumberg, Jeffrey B.
2017-01-01
Micronutrient deficiencies and inadequacies constitute a global health issue, particularly among countries in the Middle East. The objective of this review is to identify micronutrient deficits in the Middle East and to consider current and new approaches to address this problem. Based on the availability of more recent data, this review is primarily focused on countries that are in advanced nutrition transition. Prominent deficits in folate, iron, and vitamin D are noted among children/adolescents, women of childbearing age, pregnant women, and the elderly. Reports indicate that food fortification in the region is sporadic and ineffective, and the use of dietary supplements is low. Nutrition monitoring in the region is limited, and gaps in relevant information present challenges for implementing new policies and approaches to address the problem. Government-sponsored initiatives are necessary to assess current dietary intakes/patterns, support nutrition education, and to reduce food insecurity, especially among vulnerable population groups. Public–private partnerships should be considered in targeting micronutrient fortification programs and supplementation recommendations as approaches to help alleviate the burden of micronutrient deficiencies and inadequacies in the Middle East. PMID:28273802
Bet, Pierre M; Hugtenburg, Jacqueline G; Penninx, Brenda W J H; Balkom, Anton van; Nolen, Willem A; Hoogendijk, Witte J G
2013-12-15
All guidelines on major depressive disorder (MDD) and anxiety disorders recommend pharmacotherapy and/or psychological treatment for moderate to severe disease. The aim of this cross-sectional study was to investigate treatment inadequacy, both pharmacological and psychological, in a large naturalistic cohort of subjects with MDD and anxiety disorders from the Netherlands Study of Depression and Anxiety. All subjects with a current 6-month diagnosis were included (n=1662). Demographic data, clinical features and actual medication use were assessed in face-to-face interviews. In moderate to severe MDD, 43% of the subjects were not treated sufficiently with antidepressants or psychological treatment. In primary health care patients, this undertreatment was 70%. In moderate to severe anxiety disorders, 44% of the subjects were not treated sufficiently with antidepressants, benzodiazepines or psychological treatment. Among antidepressant users with moderate to severe MDD, 21% of the pharmacotherapy was inadequate with respect to drug choice, dose and every day use. Undertreatment and pharmacotherapeutic inadequacy are common in moderate to severe MDD and anxiety disorders. Both are more pronounced in primary care than in specialized care. This may be partly due to differences in disease recognition and help seeking behaviour. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.
NASA Astrophysics Data System (ADS)
Delboni, Luiz Fernando; Zambroni da Silva, Antonio Carlos; Oliveira, Denisson Queiroz
2015-04-01
The problem of voltage control and reactive power management plays a crucial role on power system's operations. Particularly, detecting the most effective control actions to reduce the system loss and enhance the voltage profile is of major interest. This paper deals with system voltage inadequacy detection. To address this problem, artificial immune system is employed considering its negative selection mechanism. Its purpose is to monitor system operation data entry and check if the voltage level is within its operating values. In this sense, the user may define the range of control, so the proposed methodology may be useful for normal and emergency operating conditions. Corrective actions are undertaken if necessary. The IEEE 34 nodes distribution system is used to test the proposed methodology.
NASA Technical Reports Server (NTRS)
Paries, Jean
1994-01-01
Automation related accidents or serious incidents are not limited to advanced technology aircraft. There is a full history of such accidents with conventional technology aircraft. However, this type of occurrence is far from sparing the newest 'glass cockpit' generation, and it even seems to be a growing contributor to its accident rate. Nevertheless, all these aircraft have been properly certificated according to the relevant airworthiness regulations. Therefore, there is a growing concern that with the technological advancement of air transport aircraft cockpits, the current airworthiness regulations addressing cockpit design and human factors may have reached some level of inadequacy. This paper reviews some aspects of the current airworthiness regulations and certification process related to human factors of cockpit design and focuses on questioning their ability to guarantee the intended safety objectives.
Maternal child-feeding practices and dietary inadequacy of 4-year-old children.
Durão, Catarina; Andreozzi, Valeska; Oliveira, Andreia; Moreira, Pedro; Guerra, António; Barros, Henrique; Lopes, Carla
2015-09-01
This study aimed to evaluate the association between maternal perceived responsibility and child-feeding practices and dietary inadequacy of 4-year-old children. We studied 4122 mothers and children enrolled in the population-based birth cohort - Generation XXI (Porto, Portugal). Mothers self-completed the Child Feeding Questionnaire and a scale on covert and overt control, and answered to a food frequency questionnaire in face-to-face interviews. Using dietary guidelines for preschool children, adequacy intervals were defined: fruit and vegetables (F&V) 4-7 times/day; dairy 3-5 times/day; meat and eggs 5-10 times/week; fish 2-4 times/week. Inadequacy was considered as below or above these cut-points. For energy-dense micronutrient-poor foods and beverages (EDF), a tolerable limit was defined (<6 times/week). Associations between maternal perceived responsibility and child-feeding practices (restriction, monitoring, pressure to eat, overt and covert control) and children's diet were examined by logistic regression models. After adjustment for maternal BMI, education, and diet, and children's characteristics (sex, BMI z-scores), restriction, monitoring, overt and covert control were associated with 11-18% lower odds of F&V consumption below the interval defined as adequate. Overt control was also associated with 24% higher odds of their consumption above it. Higher perceived responsibility was associated with higher odds of children consuming F&V and dairy above recommendations. Pressure to eat was positively associated with consumption of dairy above the adequate interval. Except for pressure to eat, maternal practices were associated with 14-27% lower odds of inadequate consumption of EDF. In conclusion, children whose mothers had higher levels of covert control, monitoring, and restriction were less likely to consume F&V below recommendations and EDF above tolerable limits. Higher overt control and pressure to eat were associated, respectively, with higher
Controversies of Sex Re-assignment in Genetic Males with Congenital Inadequacy of the Penis.
Raveenthiran, Venkatachalam
2017-07-08
Sex assignment in 46XY genetic male children with congenital inadequacy of the penis (CIP) is controversial. Traditionally, children with penile length less than 2 cm at birth are considered unsuitable to be raised as males. They are typically re-assigned to female-sex and feminizing genitoplasty is usually done in infancy. However, the concept of cerebral androgen imprinting has caused paradigm shift in the philosophy of sex re-assignment. Masculinization of the brain, rather than length of the penis, is the modern criterion of sex re-assignment in CIP. This review summarizes the current understanding of the complex issue. In 46XY children with CIP, male-sex assignment appears appropriate in non-hormonal conditions such as idiopathic micropenis, aphallia and exstrophy. Female-sex re-assignment appears acceptable in complete androgen insensitivity (CAIS), while partial androgen insensitivity syndrome (PAIS) patients are highly dissatisfied with the assignment of either sex. Children with 5-alpha reductase deficiency are likely to have spontaneous penile lengthening at puberty. Hence, they are better raised as males. Although female assignment is common in pure gonadal dysgenesis, long-term results are not known to justify the decision.
Naveed, Muhammad; Sohail, Younas; Khalid, Nauman; Ahmed, Iftikhar; Mumtaz, Abdul Samad
2015-08-01
The rhizospheric zone abutting plant roots usually clutches a wealth of microbes. In the recent past, enormous genetic resources have been excavated with potential applications in host plant interaction and ancillary aspects. Two Pseudomonas strains were isolated and identified through 16S rRNA and rpoD sequence analyses as P. fluorescens QAU67 and P. putida QAU90. Initial biochemical characterization and their root-colonizing traits indicated their potential role in plant growth promotion. Such aerobic systems, involved in gluconic acid production and phosphate solubilization, essentially require the pyrroloquinoline quinine (PQQ)- dependent glucose dehydrogenase (GDH) in the genome. The PCR screening and amplification of GDH and PQQ and subsequent induction of mutagenesis characterized their possible role as antioxidants as well as in growth promotion, as probed in vitro in lettuce and in vivo in rice, bean, and tomato plants. The results showed significant differences (p < or = 0.05) in parameters of plant height, fresh weight, and dry weight, etc., deciphering a clear and in fact complementary role of GDH and PQQ in plant growth promotion. Our study not only provides direct evidence of the in vivo role of GDH and PQQ in host plants but also reveals their functional inadequacy in the event of mutation at either of these loci.
Cognitive phylogenies, the Darwinian logic of descent, and the inadequacy of cladistic thinking.
Theofanopoulou, Constantina; Boeckx, Cedric
2015-01-01
There has been a reappraisal of phylogenetic issues in cognitive science, as reconstructing cognitive phylogenies has been considered a key for unveiling the cognitive novelties that set the stage for what makes humans special. In our opinion, the studies made until now have approached cognitive phylogenies in a non-optimal way, and we wish to both highlight their problems, drawing on recent considerations in philosophy of biology. The inadequacy of current visions on cognitive phylogenies stems from the influence of the traditional "linear cladograms," according to which every seemingly new or more sophisticated feature of a cognitive mechanism, viewed as a novelty, is represented as a node on top of the old and shared elements. We claim that this kind of cladograms does not succeed in depicting the complexity with which traits are distributed across species and, furthermore, that the labels of the nodes of these traditional representational systems fail to capture the "tinkering" nature of evolution. We argue that if we are to conceive of cognitive mechanisms in a multi-dimensional, bottom-up perspective, in accordance with the Darwinian logic of descent, we should rather focus on decomposing these mechanisms into lower-level, generic functions, which have the additional advantage of being implementable in neural matter, which ultimately produces cognition. Doing so renders current constructions of cognitive phylogenies otiose.
Jiang, Xinyin; Jones, Sara; Andrew, Benjamin Y; Ganti, Anita; Malysheva, Olga V; Giallourou, Natasa; Brannon, Patsy M; Roberson, Mark S; Caudill, Marie A
2014-08-01
Maternal choline intake during gestation may influence placental function and fetal health outcomes. Specifically, we previously showed that supplemental choline reduced placental and maternal circulating concentrations of the anti-angiogenic factor, fms-like tyrosine kinase-1 (sFLT1), in pregnant women as well as sFLT1 production in cultured human trophoblasts. The current study aimed to quantify the effect of choline on a wider array of biomarkers related to trophoblast function and to elucidate possible mechanisms. Immortalized HTR-8/SVneo trophoblasts were cultured in different choline concentrations (8, 13, and 28 µM [control]) for 96-h and markers of angiogenesis, inflammation, apoptosis, and blood vessel formation were examined. Choline insufficiency altered the angiogenic profile, impaired in vitro angiogenesis, increased inflammation, induced apoptosis, increased oxidative stress, and yielded greater levels of protein kinase C (PKC) isoforms δ and ϵ possibly through increases in the PKC activators 1-stearoyl-2-arachidonoyl-sn-glycerol and 1-stearoyl-2-docosahexaenoyl-sn-glycerol. Notably, the addition of a PKC inhibitor normalized angiogenesis and apoptosis, and partially rescued the aberrant gene expression profile. Together these results suggest that choline inadequacy may contribute to placental dysfunction and the development of disorders related to placental insufficiency by activating PKC.
Splitting methods for low Mach number Euler and Navier-Stokes equations
NASA Technical Reports Server (NTRS)
Abarbanel, Saul; Dutt, Pravir; Gottlieb, David
1987-01-01
Examined are some splitting techniques for low Mach number Euler flows. Shortcomings of some of the proposed methods are pointed out and an explanation for their inadequacy suggested. A symmetric splitting for both the Euler and Navier-Stokes equations is then presented which removes the stiffness of these equations when the Mach number is small. The splitting is shown to be stable.
LaFranchi, Stephen H; Haddow, James E; Hollowell, Joseph G
2005-01-01
A workshop entitled, "The Impact of Maternal Thyroid Diseases on the Developing Fetus: Implications for Diagnosis, Treatment, and Screening," was held in Atlanta, Georgia, January 12-13, 2004. This paper reports on the individual session that examined thyroid inadequacy during gestation as a risk factor for adverse pregnancy and developmental outcomes. For this session the following papers were presented: "Adverse Pregnancy Outcomes"; "Thyroid Physiology in the Fetus"; "New England Data: Cretinism Revisited-Preventing Fetal Brain Damage when Mothers Have Subclinical Hypothyroidism"; "Dutch Data: Pregnancy, Maternal Thyroid (Dys)function and Outcome of the Offspring"; and "Report on the Wales Controlled Antenatal Thyroid Screening Study (CATS); A Prospective RCT." These presentations were formally discussed by invited respondents well as others in attendance. Salient points from this session about which there was agreement include the following. Maternal hypothyroidism is associated with complications of pregnancy and adverse effects on the fetus. These risks are greater in women with overt hypothyroidism compared to subclinical hypothyroidism, and also appear to be increased in women with euthyroid autoimmune thyroid disease. If maternal hypothyroidism is treated adequately, this appears to reduce the risk for adverse outcomes. The demonstration of a pattern of ontogeny of fetal cerebral cortex deiodinases and thyroid hormone receptors, beginning by 7-8 weeks' gestation, is circumstantial evidence that thyroid hormone plays an important role in fetal neurodevelopment. Significant fetal thyroid hormone production and secretion does not begin until approximately 20 weeks' gestation. If there is a significant role for thyroid hormone in fetal neurodevelopment before 20 weeks' gestation, it likely is of maternal origin. Studies demonstrate low levels of thyroxine in the fetal coelomic fluid and blood prior to 12-14 weeks' gestation. Published data consistently document
Quality protein maize for Africa: closing the protein inadequacy gap in vulnerable populations.
Nuss, Emily T; Tanumihardjo, Sherry A
2011-05-01
Africa shares a unique relationship with maize (Zea mays). After its introduction from New World explorers, maize was quickly adopted as the cornerstone of local cuisine, especially in sub-Saharan countries. Although maize provides macro- and micronutrients required for humans, it lacks adequate amounts of the essential amino acids lysine and tryptophan. For those consuming >50% of their daily energy from maize, pandemic protein malnutrition may exist. Severe protein and energy malnutrition increases susceptibility to life-threatening diseases such as tuberculosis and gastroenteritis. A nutritionally superior maize cultivar named quality protein maize (QPM) represents nearly one-half century of research dedicated to malnutrition eradication. Compared with traditional maize types, QPM has twice the amount of lysine and tryptophan, as well as protein bioavailability that rivals milk casein. Animal and human studies suggest that substituting QPM for common maize results in improved health. However, QPM's practical contribution to maize-subsisting populations remains unresolved. Herein, total protein and essential amino acid requirements recommended by the WHO and the Institute of Medicine were applied to estimate QPM target intake levels for young children and adults, and these were compared with mean daily maize intakes by African country. The comparisons revealed that ~100 g QPM is required for children to maintain adequacy of lysine, the most limiting amino acid, and nearly 500 g is required for adults. This represents a 40% reduction in maize intake relative to common maize to meet protein requirements. The importance of maize in Africa underlines the potential for QPM to assist in closing the protein inadequacy gap.
Quality Protein Maize for Africa: Closing the Protein Inadequacy Gap in Vulnerable Populations12
Nuss, Emily T.; Tanumihardjo, Sherry A.
2011-01-01
Africa shares a unique relationship with maize (Zea mays). After its introduction from New World explorers, maize was quickly adopted as the cornerstone of local cuisine, especially in sub-Saharan countries. Although maize provides macro- and micronutrients required for humans, it lacks adequate amounts of the essential amino acids lysine and tryptophan. For those consuming >50% of their daily energy from maize, pandemic protein malnutrition may exist. Severe protein and energy malnutrition increases susceptibility to life-threatening diseases such as tuberculosis and gastroenteritis. A nutritionally superior maize cultivar named quality protein maize (QPM) represents nearly one-half century of research dedicated to malnutrition eradication. Compared with traditional maize types, QPM has twice the amount of lysine and tryptophan, as well as protein bioavailability that rivals milk casein. Animal and human studies suggest that substituting QPM for common maize results in improved health. However, QPM’s practical contribution to maize-subsisting populations remains unresolved. Herein, total protein and essential amino acid requirements recommended by the WHO and the Institute of Medicine were applied to estimate QPM target intake levels for young children and adults, and these were compared with mean daily maize intakes by African country. The comparisons revealed that ∼100 g QPM is required for children to maintain adequacy of lysine, the most limiting amino acid, and nearly 500 g is required for adults. This represents a 40% reduction in maize intake relative to common maize to meet protein requirements. The importance of maize in Africa underlines the potential for QPM to assist in closing the protein inadequacy gap. PMID:22332054
Goudard, Marivanda Julia Furtado; Simões, Vanda Maria Ferreira; Batista, Rosângela Fernandes Lucena; Queiroz, Rejane Christine de Souza; Alves, Maria Tereza Seabra Soares de Brito E; Coimbra, Liberata Campos; Martins, Marília da Glória; Barbieri, Marco Antônio; Nathasje, Ian Favero
2016-04-01
The scope of this study was to analyze the content of prenatal care in São Luís, Maranhão, Brazil, and the factors associated with its inadequacy. A cross-sectional study was conducted based on data from the birth cohort of São Luís in 2010. The content of prenatal care was defined as inadequate when it did not meet the criteria of the Program for Humanization of Prenatal and Delivery Care, which establishes early initiation of prenatal care, minimum number of medical consultations, basic laboratory tests, tetanus vaccination and obstetric procedures. Poisson regression was used to observe associations of the variables with the outcome. The inadequacy rate was high (60.2%). The variables associated with inadequacy were: class C socioeconomic status (PR = 1.39; CI = 1.26-1.55); class D/E socioeconomic status (PR = 1.60; CI = 1.43-1.79); unqualified/unemployed mother (PR = 1.24; CI = 1.11-1.37); 5-8 years of schooling (PR = 1.12; CI = 1.06-1.19); 0-4 years of schooling (PR = 1.13; CI = 1.01-1.26); not being religious (PR = 1.10; CI = 1.04-1.17); alcohol use during pregnancy (PR = 1.13; CI = 1.06-1.20), and being attended by the public service (PR = 1.75; CI = 1.54-2.00). The results showed inadequacy and inequality of prenatal care, revealing that women of lower socioeconomic status received lower quality care.
Brunst, Kelly J; Wright, Robert O; DiGioia, Kimberly; Enlow, Michelle Bosquet; Fernandez, Harriet; Wright, Rosalind J; Kannan, Srimathi
2014-09-01
To assess sociodemographic correlates of micronutrient intakes from food and dietary supplements in an urban, ethnically diverse sample of pregnant women in the USA. Cross-sectional analyses of data collected using a validated semi-quantitative FFQ. Associations between racial, ethnic and sociodemographic factors and micronutrient intakes were examined using logistic regression controlling for pre-pregnancy BMI, maternal age and smoking status. Prenatal clinics, Boston, MA, USA. Analyses included pregnant women (n 274) in the PRogramming of Intergenerational Stress Mechanisms (PRISM) study, an urban longitudinal cohort designed to examine how stress influences respiratory health in children when controlling for other environmental exposures (chemical stressors, nutrition). High frequencies of vitamin E (52 %), Mg (38 %), Fe (57 %) and vitamin D (77 %) inadequacies as well as suboptimal intakes of choline (95 %) and K (99 %) were observed. Factors associated with multiple antioxidant inadequacies included being Hispanic or African American, lower education and self-reported economic-related food insecurity. Hispanics had a higher prevalence of multiple methyl-nutrient inadequacies compared with African Americans; both had suboptimal betaine intakes and higher odds for vitamin B₆ and Fe inadequacies compared with Caucasians. Nearly all women (98 %) reported Na intakes above the tolerable upper limit; excessive intakes of Mg (35 %), folate (37 %) and niacin (38 %) were also observed. Women reporting excessive intakes of these nutrients were more likely Caucasian or Hispanic, more highly educated, US-born and did not report food insecurity. Racial/ethnic and other sociodemographic factors should be considered when tailoring periconceptional dietary interventions for urban ethnic women in the USA.
Verghese, Abraham; Charlton, Blake; Kassirer, Jerome P; Ramsey, Meghan; Ioannidis, John P A
2015-12-01
Oversights in the physical examination are a type of medical error not easily studied by chart review. They may be a major contributor to missed or delayed diagnosis, unnecessary exposure to contrast and radiation, incorrect treatment, and other adverse consequences. Our purpose was to collect vignettes of physical examination oversights and to capture the diversity of their characteristics and consequences. A cross-sectional study using an 11-question qualitative survey for physicians was distributed electronically, with data collected from February to June of 2011. The participants were all physicians responding to e-mail or social media invitations to complete the survey. There were no limitations on geography, specialty, or practice setting. Of the 208 reported vignettes that met inclusion criteria, the oversight was caused by a failure to perform the physical examination in 63%; 14% reported that the correct physical examination sign was elicited but misinterpreted, whereas 11% reported that the relevant sign was missed or not sought. Consequence of the physical examination inadequacy included missed or delayed diagnosis in 76% of cases, incorrect diagnosis in 27%, unnecessary treatment in 18%, no or delayed treatment in 42%, unnecessary diagnostic cost in 25%, unnecessary exposure to radiation or contrast in 17%, and complications caused by treatments in 4%. The mode of the number of physicians missing the finding was 2, but many oversights were missed by many physicians. Most oversights took up to 5 days to identify, but 66 took longer. Special attention and skill in examining the skin and its appendages, as well as the abdomen, groin, and genitourinary area could reduce the reported oversights by half. Physical examination inadequacies are a preventable source of medical error, and adverse events are caused mostly by failure to perform the relevant examination. Copyright © 2015 Elsevier Inc. All rights reserved.
ERIC Educational Resources Information Center
Heikonen, Lauri; Pietarinen, Janne; Pyhältö, Kirsi; Toom, Auli; Soini, Tiina
2017-01-01
Teachers' capacity to learn intentionally and responsively in the classroom is particularly vulnerable during the first years in the profession. This study investigated the interrelations between early career teachers' turnover intentions, perceived inadequacy in teacher-student interaction, and sense of professional agency in the classroom. The…
NASA Astrophysics Data System (ADS)
Lee, Haksu; Seo, Dong-Jun; Noh, Seong Jin
2016-11-01
This paper presents a simple yet effective weakly-constrained (WC) data assimilation (DA) approach for hydrologic models which accounts for model structural inadequacies associated with rainfall-runoff transformation processes. Compared to the strongly-constrained (SC) DA, WC DA adjusts the control variables less while producing similarly or more accurate analysis. Hence the adjusted model states are dynamically more consistent with those of the base model. The inadequacy of a rainfall-runoff model was modeled as an additive error to runoff components prior to routing and penalized in the objective function. Two example modeling applications, distributed and lumped, were carried out to investigate the effects of the WC DA approach on DA results. For distributed modeling, the distributed Sacramento Soil Moisture Accounting (SAC-SMA) model was applied to the TIFM7 Basin in Missouri, USA. For lumped modeling, the lumped SAC-SMA model was applied to nineteen basins in Texas. In both cases, the variational DA (VAR) technique was used to assimilate discharge data at the basin outlet. For distributed SAC-SMA, spatially homogeneous error modeling yielded updated states that are spatially much more similar to the a priori states, as quantified by Earth Mover's Distance (EMD), than spatially heterogeneous error modeling by up to ∼10 times. DA experiments using both lumped and distributed SAC-SMA modeling indicated that assimilating outlet flow using the WC approach generally produce smaller mean absolute difference as well as higher correlation between the a priori and the updated states than the SC approach, while producing similar or smaller root mean square error of streamflow analysis and prediction. Large differences were found in both lumped and distributed modeling cases between the updated and the a priori lower zone tension and primary free water contents for both WC and SC approaches, indicating possible model structural deficiency in describing low flows or
NASA Astrophysics Data System (ADS)
Chaouadi, R.
2007-02-01
Irradiation embrittlement studies rely very often on Charpy impact data, in particular the ductile-to-brittle transition temperature (DBTT). However, while the DBTT-shift is equivalent to the increase of the fracture toughness transition temperature of ferritic steels, it is not the case for ferritic/martensitic steels. The aim of this study is to critically assess experimental data obtained on a 9%Cr-ferritic/martensitic steel, Eurofer-97, to better understand the underlying mechanisms involved during the fracture process. More specifically, a dedicated analysis using the load diagram approach allows to unambiguously reveal the actual effects of irradiation on physically rather than empirically based parameters. A comparison is made between a ferritic and ferritic/martensitic steel to better identify the possible similarities and differences. Tensile, Charpy impact and fracture toughness tests data are examined in a global approach to assess the actual rather than apparent irradiation effects. The adequacy or inadequacy of the Charpy impact test to monitor irradiation effects is extensively discussed.
Inadequacies of Dogmatic Realism
1996-01-01
OFIDEALISM Twentieth-century history testties that efforts to blend morahty and pohttcs have not only often fatled, but also have caused perverse effects...rational analysis of lustoncal evidence concernmg the behavior of mdlmduals and nation states. Oswald Spengler, the mfluentlal ktoncal pUosopher whose...to mtematlonal behavior There are no absolute values m the pohtical realm of the Reakt Each nation, culture, and society detemes its own values
Chrysos, Michael
2017-01-14
We focus on the long-pending issue of the inadequacy of the Dirac bubble potential model in the description of He-He interactions in the continuum [L. L. Lohr and S. M. Blinder, Int. J. Quantum Chem. 53, 413 (1995)]. We attribute this failure to the lack of a potential wall to mimic the onset of the repulsive interaction at close range separations. This observation offers the explanation to why this excessively simple model proves incapable of quantitatively reproducing previous experimental findings of glory scattering in He-He, although being notorious for its capability of reproducing several distinctive features of the atomic and isotopic helium dimers and trimers [L. L. Lohr and S. M. Blinder, Int. J. Quantum Chem. 90, 419 (2002)]. Here, we show that an infinitely high, energy-dependent potential wall of properly calculated thickness rc(E) taken as a supplement to the Dirac bubble potential suffices for agreement with variable-energy elastic collision cross section experiments for (4)He-(4)He, (3)He-(4)He, and (3)He-(3)He [R. Feltgen et al., J. Chem. Phys. 76, 2360 (1982)]. In the very low energy regime, consistency is found between the Dirac bubble potential (to which our extended model is shown to reduce) and cold collision experiments [J. C. Mester et al., Phys. Rev. Lett. 71, 1343 (1993)]; this consistency, which in this regime lends credence to the Dirac bubble potential, was never noticed by its authors. The revised model being still analytic is of high didactical value while expected to increase in predictive power relative to other appraisals.
Bezrati, Ikram; Ben Fradj, Mohamed Kacem; Ouerghi, Nejmeddine; Feki, Moncef; Chaouachi, Anis; Kaabachi, Naziha
2016-01-01
Background Vitamin D inadequacy is widespread in children and adolescents worldwide. The present study was undertaken to assess the vitamin D status in active children living in a sunny climate and to identify the main determinants of the serum concentration of 25-hydroxyvitamin D (25-OHD). Methods This cross-sectional study included 225 children aged 7–15 years practicing sports in a football academy. Anthropometric measures were performed to calculate body mass index (BMI), fat mass, and maturity status. A nutritional enquiry was performed including 3-day food records and food frequency questionnaire. Plasma 25-OHD and insulin were assessed by immunoenzymatic methods ensuring categorization of vitamin D status and calculation of insulin sensitivity/resistance indexes. A logistic regression model was applied to identify predictors for vitamin D inadequacy. Results Vitamin D deficiency (25-OHD<12 µg/L) was observed in 40.9% of children and insufficiency (12<25-OHD<20 µg/L) was observed in 44% of children. In a multivariate analysis, vitamin D deficiency and insufficiency were associated with a lower dietary intake of vitamin D, proteins, milk, red meat, fish, and eggs. However, no significant relationship was observed with maturation status, adiposity, or insulin resistance. Conclusions Tunisian children and adolescents are exposed to a high risk of vitamin D inadequacy despite living in a sunny climate. Circulating 25-OHD concentrations are related to the intake of vitamin D food sources but not to maturation status or body composition. Ensuring sufficient and safe sun exposure and adequate vitamin D intake may prevent vitamin D inadequacy in children from sunny environments. PMID:27113441
Young, C.W.
1997-10-01
In 1967, Sandia National Laboratories published empirical equations to predict penetration into natural earth materials and concrete. Since that time there have been several small changes to the basic equations, and several more additions to the overall technique for predicting penetration into soil, rock, concrete, ice, and frozen soil. The most recent update to the equations was published in 1988, and since that time there have been changes in the equations to better match the expanding data base, especially in concrete penetration. This is a standalone report documenting the latest version of the Young/Sandia penetration equations and related analytical techniques to predict penetration into natural earth materials and concrete. 11 refs., 6 tabs.
NASA Astrophysics Data System (ADS)
Britz, Dieter
In this chapter, we present most of the equations that apply to the systems and processes to be dealt with later. Most of these are expressed as equations of concentration dynamics, that is,concentration of one or more solution species as a function of time, as well as other variables, in the form of differential equations. Fundamentally, these are transport (diffusion-, convection- and migration-) equations but may be complicated by chemical processes occurring heterogeneously (i.e. at the electrode surface - electrochemical reaction) or homogeneously (in the solution bulk - chemical reaction). The transport components are all included in the general Nernst-Planck equation (see also Bard and Faulkner 2001) for the flux J j of species j
NASA Astrophysics Data System (ADS)
Prentis, Jeffrey J.
1996-05-01
One of the most challenging goals of a physics teacher is to help students see that the equations of physics are connected to each other, and that they logically unfold from a small number of basic ideas. Derivations contain the vital information on this connective structure. In a traditional physics course, there are many problem-solving exercises, but few, if any, derivation exercises. Creating an equation poem is an exercise to help students see the unity of the equations of physics, rather than their diversity. An equation poem is a highly refined and eloquent set of symbolic statements that captures the essence of the derivation of an equation. Such a poetic derivation is uncluttered by the extraneous details that tend to distract a student from understanding the essential physics of the long, formal derivation.
Liu, Zhenhua; Choi, Sang-Woon; Crott, Jimmy W.; Smith, Donald E.; Mason, Joel B.
2009-01-01
Folate is required for biological methylation and nucleotide synthesis, aberrations of which are thought to be the mechanisms that enhance colorectal carcinogenesis produced by folate inadequacy. These functions of folate also depend on the availability of other B-vitamins that participate in “one-carbon metabolism,” including B2, B6 and B12. Our study therefore investigated whether combined dietary restriction of these vitamins amplifies aberrations in the epigenetic and genetic integrity of the p53 gene that is induced by folate depletion alone. Ninety-six mice were group pair-fed diets with different combinations of B-vitamin depletion over 10 weeks. DNA and RNA were extracted from epithelial cells isolated from the colon. Within the hypermutable region of p53 (exons 5–8), DNA strand breaks were induced within exons 6 and 8 by folate combined with B2, B6 and B12 restriction (p < 0.05); such effects were not significantly induced by mild folate depletion alone. Similarly, a minor degree of hypomethylation of exon 6 produced by isolated folate depletion was significantly amplified (p ≤ 0.05) by simultaneous depletion of all 4 B-vitamins. Furthermore, the expression of p53 and MDM2 were significantly decreased (p ≤ 0.05) by the combined depletion state but not by folate depletion alone. These data indicate that inadequacies of other 1-carbon vitamins may amplify aberrations of the p53 gene induced by folate depletion alone, implying that concurrent inadequacies in several of these vitamins may have added tumorigenic potential beyond that observed with isolated folate depletion. PMID:18498130
NASA Astrophysics Data System (ADS)
Viljamaa, Panu; Jacobs, J. Richard; Chris; JamesHyman; Halma, Matthew; EricNolan; Coxon, Paul
2014-07-01
In reply to a Physics World infographic (part of which is given above) about a study showing that Euler's equation was deemed most beautiful by a group of mathematicians who had been hooked up to a functional magnetic-resonance image (fMRI) machine while viewing mathematical expressions (14 May, http://ow.ly/xHUFi).
DOE R&D Accomplishments Database
1998-09-21
In the late 1950s to early 1960s Rudolph A. Marcus developed a theory for treating the rates of outer-sphere electron-transfer reactions. Outer-sphere reactions are reactions in which an electron is transferred from a donor to an acceptor without any chemical bonds being made or broken. (Electron-transfer reactions in which bonds are made or broken are referred to as inner-sphere reactions.) Marcus derived several very useful expressions, one of which has come to be known as the Marcus cross-relation or, more simply, as the Marcus equation. It is widely used for correlating and predicting electron-transfer rates. For his contributions to the understanding of electron-transfer reactions, Marcus received the 1992 Nobel Prize in Chemistry. This paper discusses the development and use of the Marcus equation. Topics include self-exchange reactions; net electron-transfer reactions; Marcus cross-relation; and proton, hydride, atom and group transfers.
Adequacy of the virial equation of state and cluster expansion
NASA Astrophysics Data System (ADS)
Ushcats, M. V.
2013-04-01
The limits for the accuracy of the virial expansion and the problem of its divergence have been investigated using the exact cluster expansion of the configuration integral. In the subcritical temperature regimes the virial equation of state is applicable up to the singularity point of the isothermal compressibility, i.e., to the possible beginning of the condensation process. At supercritical temperatures this equation should be applicable within the region where the cluster expansion is adequate. The problem of the virial series divergence has been found to be irrelevant to the actual behavior of the cluster expansion. Considering the Lennard-Jones fluid as well as the system of hard spheres, the inadequate behavior of the cluster expansion has been discovered in the high density regime. The major reason for this inadequacy should be the basic simplification of the cluster expansion: the integration of irreducible diagrams over the infinite limits.
Adequacy of the virial equation of state and cluster expansion.
Ushcats, M V
2013-04-01
The limits for the accuracy of the virial expansion and the problem of its divergence have been investigated using the exact cluster expansion of the configuration integral. In the subcritical temperature regimes the virial equation of state is applicable up to the singularity point of the isothermal compressibility, i.e., to the possible beginning of the condensation process. At supercritical temperatures this equation should be applicable within the region where the cluster expansion is adequate. The problem of the virial series divergence has been found to be irrelevant to the actual behavior of the cluster expansion. Considering the Lennard-Jones fluid as well as the system of hard spheres, the inadequate behavior of the cluster expansion has been discovered in the high density regime. The major reason for this inadequacy should be the basic simplification of the cluster expansion: the integration of irreducible diagrams over the infinite limits.
Liu, Zhenhua; Ciappio, Eric D.; Crott, Jimmy W.; Brooks, Ryan S.; Nesvet, Jared; Smith, Donald E.; Choi, Sang-Woon; Mason, Joel B.
2011-01-01
The Wnt pathway is a pivotal signaling cascade in colorectal carcinogenesis. The purpose of this work is to determine whether depletion of folate and other metabolically related B vitamins induces in vivo activation of intestinal Wnt signaling and whether this occurs in parallel with increased tumorigenesis. A hybrid mouse was created by crossing a Wnt-reporter animal (BAT-LacZ) with a model of colorectal cancer (Apc1638N). A mild depletion of folate and vitamins B2, B6, and B12 was induced over 16 wk, and the control animals in each instance were pair fed a diet containing the basal requirement of these nutrients. The multiplicity of macroscopic tumors and aberrant crypt foci both increased by ∼50% in the hybrid mice fed the depletion diet (P<0.05). A 4-fold elevation in Wnt signaling was produced by the depletion diet (P<0.05) and was accompanied by significant changes in the expression of a number of Wnt-related genes in a pattern consistent with its activation. Proliferation and apoptosis of the colonic mucosa both changed in a protransformational direction (P<0.05). In summary, mild depletion of multiple B vitamins produces in vivo activation of colonic Wnt signaling, implicating it as a key pathway by which B-vitamin inadequacies enhance intestinal tumorigenesis.—Liu, Z., Ciappio, E. D., Crott, J. W., Brooks, R. S., Nesvet, J., Smith, D. E., Choi, S.-W., Mason, J. B. Combined inadequacies of multiple B vitamins amplify colonic Wnt signaling and promote intestinal tumorigenesis in BAT-LacZ×Apc1638N mice. PMID:21646397
2007-01-01
A b. Given an arbitrary relation→, we write →• for the total relation that extends→ by adding a pair a→• a for each a such that there is no b with a→ b...kind of a sort s is denoted by [s]. We write TΣ,k and TΣ,k(~x) to denote respectively the set of ground Σ-terms with kind k and of Σ-terms with kind k...variables. In membership equational logic, subsort relations and operator overloading are just a convenient way of writing corresponding Horn clauses
Knebel, Harley J.
1974-01-01
A deductive approach to the problem of determining the movement and effects of spilled oil over the Outer Continental Shelf requires that the potential paths of oil be determined first, in order that critical subareas may be defined for later studies. The paths of spilled oil, in turn, depend primarily on the temporal and spatial variability of four factors: the thermohaline structure of the waters, the circulation of the water, the winds, and the distribution of suspended matter. A review of the existent data concerning these factors for the Baltimore Canyon Trough area (a relatively well studied segment of the Continental Shelf) reveals that the movement and dispersal of potential oil spills cannot be reliably predicted. Variations in the thermohaline structure of waters and in the distribution of suspended matter are adequately known; the uncertainty is due to insufficient wind and storm statistics and to the lack of quantitative understanding of the relationship between the nontidal drift and its basic driving mechanisms. Similar inadequacies should be anticipated for other potentially leasable areas of the shelf because an understanding of the movement of spilled oil has not been the underlying aim of most previous studies.
Grover, P K; Cummins, A G; Price, T J; Roberts-Thomson, I C; Hardingham, J E
2014-08-01
Increasing evidence suggests that circulating tumour cells (CTCs) are responsible for metastatic relapse and this has fuelled interest in their detection and quantification. Although numerous methods have been developed for the enrichment and detection of CTCs, none has yet reached the 'gold' standard. Since epithelial cell adhesion molecule (EpCAM)-based enrichment of CTCs offers several advantages, it is one of the most commonly used and has been adapted for high-throughput technology. However, emerging evidence suggests that CTCs are highly heterogeneous: they consist of epithelial tumour cells, epithelial-to-mesenchymal transition (EMT) cells, hybrid (epithelial/EMT(+)) tumour cells, irreversible EMT(+) tumour cells, and circulating tumour stem cells (CTSCs). The EpCAM-based approach does not detect CTCs expressing low levels of EpCAM and non-epithelial phenotypes such as CTSCs and those that have undergone EMT and no longer express EpCAM. Thus, the approach may lead to underestimation of the significance of CTCs, in general, and CTSCs and EMT(+) tumour cells, in particular, in cancer dissemination. Here, we provide a critical review of research literature on the evolving concept of CTCs and the inadequacy of their enrichment by EpCAM-based technology for basic and clinical cancer research. The review also outlines future perspectives in the field. © The Author 2014. Published by Oxford University Press on behalf of the European Society for Medical Oncology. All rights reserved. For permissions, please email: journals.permissions@oup.com.
Shore, B.W.
1981-01-30
The equations of motion are discussed which describe time dependent population flows in an N-level system, reviewing the relationship between incoherent (rate) equations, coherent (Schrodinger) equations, and more general partially coherent (Bloch) equations. Approximations are discussed which replace the elaborate Bloch equations by simpler rate equations whose coefficients incorporate long-time consequences of coherence.
Equating Error in Observed-Score Equating
ERIC Educational Resources Information Center
van der Linden, Wim J.
2006-01-01
Traditionally, error in equating observed scores on two versions of a test is defined as the difference between the transformations that equate the quantiles of their distributions in the sample and population of test takers. But it is argued that if the goal of equating is to adjust the scores of test takers on one version of the test to make…
NASA Technical Reports Server (NTRS)
Hamrock, B. J.; Dowson, D.
1981-01-01
Lubricants, usually Newtonian fluids, are assumed to experience laminar flow. The basic equations used to describe the flow are the Navier-Stokes equation of motion. The study of hydrodynamic lubrication is, from a mathematical standpoint, the application of a reduced form of these Navier-Stokes equations in association with the continuity equation. The Reynolds equation can also be derived from first principles, provided of course that the same basic assumptions are adopted in each case. Both methods are used in deriving the Reynolds equation, and the assumptions inherent in reducing the Navier-Stokes equations are specified. Because the Reynolds equation contains viscosity and density terms and these properties depend on temperature and pressure, it is often necessary to couple the Reynolds with energy equation. The lubricant properties and the energy equation are presented. Film thickness, a parameter of the Reynolds equation, is a function of the elastic behavior of the bearing surface. The governing elasticity equation is therefore presented.
Variational Derivation of Dissipative Equations
NASA Astrophysics Data System (ADS)
Sogo, Kiyoshi
2017-03-01
A new variational principle is formulated to derive various dissipative equations. Model equations considered are the damping equation, Bloch equation, diffusion equation, Fokker-Planck equation, Kramers equation and Smoluchowski equation. Each equation and its time reversal equation are simultaneously obtained in our variational principle.
NASA Astrophysics Data System (ADS)
Dimakis, Aristophanes; Müller-Hoissen, Folkert
2015-06-01
It is shown that higher Bruhat orders admit a decomposition into a higher Tamari order, the corresponding dual Tamari order, and a ''mixed order''. We describe simplex equations (including the Yang-Baxter equation) as realizations of higher Bruhat orders. Correspondingly, a family of ''polygon equations'' realizes higher Tamari orders. They generalize the well-known pentagon equation. The structure of simplex and polygon equations is visualized in terms of deformations of maximal chains in posets forming 1-skeletons of polyhedra. The decomposition of higher Bruhat orders induces a reduction of the N-simplex equation to the (N+1)-gon equation, its dual, and a compatibility equation.
Jomaa, Lamis; Naja, Farah; Cheaib, Ruba; Hwalla, Nahla
2017-06-12
Mixed evidence exists with respect to the association between household food insecurity (HFIS) and obesity in low-to-middle income countries (LMICs), particularly among women. This study aimed to measure socioeconomic correlates of HFIS and explores its association with dietary intake and odds of obesity among mothers in Lebanon, a middle-income country undergoing nutrition transition. A cross-sectional study was conducted among a representative sample of households (n = 378) in Beirut, Lebanon. Surveys were completed with mothers of children <18 years. HFIS was measured using a locally-validated, Arabic-translated Household Food Insecurity Access Scale (HFIAS). Dietary intake was assessed using the multiple pass 24-h recall method. Associations between HFIS (food vs food insecure) and socio-demographic characteristics were reported using crude and adjusted odds ratios. The odds of consuming <2/3rd Dietary Reference Intakes (DRIs) for nutrients among mothers from food secure and food insecure households were explored. In addition, logistic regression analyses were conducted to explore the association of HFIS with obesity (BMI ≥ 30 kg/m2) and at-risk waist circumference (WC ≥ 80 cm) among mothers. HFIS was found among 50% of study sample and was inversely associated with household income and mother's educational level, even after adjusting for other socioeconomic variables (p < 0.01). Mothers in food insecure households reported consuming significantly less dairy products, fruits, and nuts yet more breads and sweets; and they had higher odds of consuming <2/3rd the DRI's for key micronutrients (potassium, folate, and vitamin C) compared to secure ones. Adjusting for socioeconomic correlates, food insecure mothers had 1.73 odds of obesity (95% CI: 1.02-2.92) compared to food secure mothers. High HFIS prevalence was reported among urban Lebanese households. Mothers from food insecure households had a high risk of dietary inadequacy and obesity. Adequate
Chan, Yen-Ming; MacFarlane, Amanda J; O'Connor, Deborah L
2015-11-01
Mandatory folic acid fortification of white-wheat flour and selected other grain products has reduced the prevalence of neural tube defects in Canada; however, the fortification of whole-wheat flour is not permitted. The objective of this study was to model the impact of adding folic acid to whole-wheat flour on the folate intake distribution of Canadians. Twenty-four-hour dietary recall and supplement intake data (n = 35,107) collected in the 2004 Canadian Community Health Survey 2.2 were used to calculate the prevalence of folate inadequacy (POFI) and the proportion of folic acid intakes above the Tolerable Upper Intake Level (UL). In model 1, folic acid was added to whole-wheat flour-containing foods in amounts comparable to those that are mandatory for white-wheat flour-containing foods. In model 2, a 50% overage of folic acid fortification was considered. Models 3 and 4 included assessment of folate intake distributions in adult whole-wheat consumers with or without a fortification overage. SIDE (Software for Intake Distribution Estimation; Department of Statistics and Center for Agricultural and Rural Development, Iowa State University) was used to estimate usual folate intakes. Mean folate intakes increased by ∼ 5% in all sex and age groups when whole-wheat foods were fortified (models 1 and 2; P < 0.0001). Folic acid fortification of whole-wheat flour-containing foods did not change the POFI or percentage of intakes above the UL in the general population, whether in supplement users or nonusers. Among whole-wheat consumers, the POFI was reduced by 10 percentage points after fortification of whole-wheat flour-containing foods (95% CIs did not overlap). The percentage of whole-wheat consumers with intakes above the UL did not change. Although folic acid fortification of whole-wheat flour-containing foods is unlikely to change the POFI or proportion of folic acid intakes above the UL in the general Canadian population, this fortification strategy may reduce
ERIC Educational Resources Information Center
Blakley, G. R.
1982-01-01
Reviews mathematical techniques for solving systems of homogeneous linear equations and demonstrates that the algebraic method of balancing chemical equations is a matter of solving a system of homogeneous linear equations. FORTRAN programs using this matrix method to chemical equation balancing are available from the author. (JN)
Kinetic energy equations for the average-passage equation system
NASA Technical Reports Server (NTRS)
Johnson, Richard W.; Adamczyk, John J.
1989-01-01
Important kinetic energy equations derived from the average-passage equation sets are documented, with a view to their interrelationships. These kinetic equations may be used for closing the average-passage equations. The turbulent kinetic energy transport equation used is formed by subtracting the mean kinetic energy equation from the averaged total instantaneous kinetic energy equation. The aperiodic kinetic energy equation, averaged steady kinetic energy equation, averaged unsteady kinetic energy equation, and periodic kinetic energy equation, are also treated.
NASA Technical Reports Server (NTRS)
Dyall, Kenneth G.; Faegri, Knut, Jr.
1990-01-01
The paper investigates bounds failure in calculations using Gaussian basis sets for the solution of the one-electron Dirac equation for the 2p1/2 state of Hg(79+). It is shown that bounds failure indicates inadequacies in the basis set, both in terms of the exponent range and the number of functions. It is also shown that overrepresentation of the small component space may lead to unphysical results. It is concluded that it is important to use matched large and small component basis sets with an adequate size and exponent range.
NASA Technical Reports Server (NTRS)
Dyall, Kenneth G.; Faegri, Knut, Jr.
1990-01-01
The paper investigates bounds failure in calculations using Gaussian basis sets for the solution of the one-electron Dirac equation for the 2p1/2 state of Hg(79+). It is shown that bounds failure indicates inadequacies in the basis set, both in terms of the exponent range and the number of functions. It is also shown that overrepresentation of the small component space may lead to unphysical results. It is concluded that it is important to use matched large and small component basis sets with an adequate size and exponent range.
Turbulent flow past a backward-facing step - A critical evaluation of two-equation models
NASA Technical Reports Server (NTRS)
Thangam, S.; Speziale, C. G.
1992-01-01
The ability of two-equation models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward facing step is chosen as a test case in an effort to resolve the variety of conflicting results that were published during the past decade concerning the performance of two-equation models. It is found that the errors in the reported predictions of the k-epsilon model have two major origins: (1) numerical problems arising from inadequate resolution, and (2) inaccurate predictions for normal Reynolds stress differences arising from the use of an isotropic eddy viscosity. Inadequacies in near wall modelling play a substantially smaller role. Detailed calculations are presented which strongly indicate the standard k-epsilon model - when modified with an independently calibrated anisotropic eddy viscosity - can yield surprisingly good predictions for the backstep problem.
Single wall penetration equations
NASA Technical Reports Server (NTRS)
Hayashida, K. B.; Robinson, J. H.
1991-01-01
Five single plate penetration equations are compared for accuracy and effectiveness. These five equations are two well-known equations (Fish-Summers and Schmidt-Holsapple), two equations developed by the Apollo project (Rockwell and Johnson Space Center (JSC), and one recently revised from JSC (Cour-Palais). They were derived from test results, with velocities ranging up to 8 km/s. Microsoft Excel software was used to construct a spreadsheet to calculate the diameters and masses of projectiles for various velocities, varying the material properties of both projectile and target for the five single plate penetration equations. The results were plotted on diameter versus velocity graphs for ballistic and spallation limits using Cricket Graph software, for velocities ranging from 2 to 15 km/s defined for the orbital debris. First, these equations were compared to each other, then each equation was compared with various aluminum projectile densities. Finally, these equations were compared with test results performed at JSC for the Marshall Space Flight Center. These equations predict a wide variety of projectile diameters at a given velocity. Thus, it is very difficult to choose the 'right' prediction equation. The thickness of a single plate could have a large variation by choosing a different penetration equation. Even though all five equations are empirically developed with various materials, especially for aluminum alloys, one cannot be confident in the shield design with the predictions obtained by the penetration equations without verifying by tests.
Interpretation of Bernoulli's Equation.
ERIC Educational Resources Information Center
Bauman, Robert P.; Schwaneberg, Rolf
1994-01-01
Discusses Bernoulli's equation with regards to: horizontal flow of incompressible fluids, change of height of incompressible fluids, gases, liquids and gases, and viscous fluids. Provides an interpretation, properties, terminology, and applications of Bernoulli's equation. (MVL)
Reflections on Chemical Equations.
ERIC Educational Resources Information Center
Gorman, Mel
1981-01-01
The issue of how much emphasis balancing chemical equations should have in an introductory chemistry course is discussed. The current heavy emphasis on finishing such equations is viewed as misplaced. (MP)
Random equations in aerodynamics
NASA Technical Reports Server (NTRS)
Bharucha-Reid, A. T.
1984-01-01
Literature was reviewed to identify aerodynamic models which might be treated by probablistic methods. The numerical solution of some integral equations that arise in aerodynamical problems were investigated. On the basis of the numerical studies a qualitative theory of random integral equations was developed to provide information on the behavior of the solutions of these equations (in particular, boundary and asymptotic behavior, and stability) and their statistical properties without actually obtaining explicit solutions of the equations.
Parametrically defined differential equations
NASA Astrophysics Data System (ADS)
Polyanin, A. D.; Zhurov, A. I.
2017-01-01
The paper deals with nonlinear ordinary differential equations defined parametrically by two relations. It proposes techniques to reduce such equations, of the first or second order, to standard systems of ordinary differential equations. It obtains the general solution to some classes of nonlinear parametrically defined ODEs dependent on arbitrary functions. It outlines procedures for the numerical solution of the Cauchy problem for parametrically defined differential equations.
Integrable nonlinear relativistic equations
NASA Astrophysics Data System (ADS)
Hadad, Yaron
This work focuses on three nonlinear relativistic equations: the symmetric Chiral field equation, Einstein's field equation for metrics with two commuting Killing vectors and Einstein's field equation for diagonal metrics that depend on three variables. The symmetric Chiral field equation is studied using the Zakharov-Mikhailov transform, with which its infinitely many local conservation laws are derived and its solitons on diagonal backgrounds are studied. It is also proven that it is equivalent to a novel equation that poses a fascinating similarity to the Sinh-Gordon equation. For the 1+1 Einstein equation the Belinski-Zakharov transformation is explored. It is used to derive explicit formula for N gravitational solitons on arbitrary diagonal background. In particular, the method is used to derive gravitational solitons on the Einstein-Rosen background. The similarities and differences between the attributes of the solitons of the symmetric Chiral field equation and those of the 1+1 Einstein equation are emphasized, and their origin is pointed out. For the 1+2 Einstein equation, new equations describing diagonal metrics are derived and their compatibility is proven. Different gravitational waves are studied that naturally extend the class of Bondi-Pirani-Robinson waves. It is further shown that the Bondi-Pirani-Robinson waves are stable with respect to perturbations of the spacetime. Their stability is closely related to the stability of the Schwarzschild black hole and the relation between the two allows to conjecture about the stability of a wide range of gravitational phenomena. Lastly, a new set of equations that describe weak gravitational waves is derived. This new system of equations is closely and fundamentally connected with the nonlinear Schrodinger equation and can be properly called the nonlinear Schrodinger-Einstein equations. A few preliminary solutions are constructed.
ERIC Educational Resources Information Center
Fay, Temple H.
2002-01-01
We investigate the pendulum equation [theta] + [lambda][squared] sin [theta] = 0 and two approximations for it. On the one hand, we suggest that the third and fifth-order Taylor series approximations for sin [theta] do not yield very good differential equations to approximate the solution of the pendulum equation unless the initial conditions are…
Hwalla, Nahla; Al Dhaheri, Ayesha Salem; Radwan, Hadia; Alfawaz, Hanan Abdullah; Fouda, Mona A; Al-Daghri, Nasser Mohammed; Zaghloul, Sahar; Blumberg, Jeffrey B
2017-03-03
Micronutrient deficiencies and inadequacies constitute a global health issue, particularly among countries in the Middle East. The objective of this review is to identify micronutrient deficits in the Middle East and to consider current and new approaches to address this problem. Based on the availability of more recent data, this review is primarily focused on countries that are in advanced nutrition transition. Prominent deficits in folate, iron, and vitamin D are noted among children/adolescents, women of childbearing age, pregnant women, and the elderly. Reports indicate that food fortification in the region is sporadic and ineffective, and the use of dietary supplements is low. Nutrition monitoring in the region is limited, and gaps in relevant information present challenges for implementing new policies and approaches to address the problem. Government-sponsored initiatives are necessary to assess current dietary intakes/patterns, support nutrition education, and to reduce food insecurity, especially among vulnerable population groups. Public-private partnerships should be considered in targeting micronutrient fortification programs and supplementation recommendations as approaches to help alleviate the burden of micronutrient deficiencies and inadequacies in the Middle East.
Perignon, Marlène; Barré, Tangui; Gazan, Rozenn; Amiot, Marie-Josèphe; Darmon, Nicole
2018-01-01
Nutritional adequacy depends on nutrient intakes and bioavailability which strongly varies with the plant- or animal-origin of foods. The aim was to estimate iron, zinc, protein and vitamin A bioavailability from individual diets, and investigate its relation with the animal-to-plant ratio (A/P) of diets. Bioavailability was estimated in 1899 French diets using diet-based algorithms or food-group specific conversion factors. Nutrient inadequacy was estimated based on i) bioavailability calculated in each individual diet and ii) average bioavailability assumed for Western-diets. Mean iron absorption, zinc absorption, protein quality and β-carotene conversion factor were 13%, 30%, 92%, and 17:1, respectively. Bioavailability displayed a high variability between individual diets, poorly explained by their A/P. Using individual bioavailability led to different inadequacy prevalence than with average factors assumed for Western-diets. In this population, the A/P does not seem sufficient to predict nutrient bioavailability and the corresponding recommended intakes. Nutritional adequacy should be assessed using bioavailability accounting for individual diets composition. Copyright © 2016 Elsevier Ltd. All rights reserved.
The SQG Equation as a Geodesic Equation
NASA Astrophysics Data System (ADS)
Washabaugh, Pearce
2016-12-01
We demonstrate that the surface quasi-geostrophic (SQG) equation given by θ_t + < u, nabla θrangle = 0,quad θ = nabla × (-Δ)^{-1/2} u, is the geodesic equation on the group of volume-preserving diffeomorphisms of a Riemannian manifold M in the right-invariant {dot{H}^{-1/2}} metric. We show by example, that the Riemannian exponential map is smooth and non-Fredholm, and that the sectional curvature at the identity is unbounded of both signs.
Fractional chemotaxis diffusion equations.
Langlands, T A M; Henry, B I
2010-05-01
We introduce mesoscopic and macroscopic model equations of chemotaxis with anomalous subdiffusion for modeling chemically directed transport of biological organisms in changing chemical environments with diffusion hindered by traps or macromolecular crowding. The mesoscopic models are formulated using continuous time random walk equations and the macroscopic models are formulated with fractional order differential equations. Different models are proposed depending on the timing of the chemotactic forcing. Generalizations of the models to include linear reaction dynamics are also derived. Finally a Monte Carlo method for simulating anomalous subdiffusion with chemotaxis is introduced and simulation results are compared with numerical solutions of the model equations. The model equations developed here could be used to replace Keller-Segel type equations in biological systems with transport hindered by traps, macromolecular crowding or other obstacles.
NASA Astrophysics Data System (ADS)
Kostov, Ivan; Serban, Didina; Volin, Dmytro
2008-08-01
We give a realization of the Beisert, Eden and Staudacher equation for the planar Script N = 4 supersymetric gauge theory which seems to be particularly useful to study the strong coupling limit. We are using a linearized version of the BES equation as two coupled equations involving an auxiliary density function. We write these equations in terms of the resolvents and we transform them into a system of functional, instead of integral, equations. We solve the functional equations perturbatively in the strong coupling limit and reproduce the recursive solution obtained by Basso, Korchemsky and Kotański. The coefficients of the strong coupling expansion are fixed by the analyticity properties obeyed by the resolvents.
Solving Ordinary Differential Equations
NASA Technical Reports Server (NTRS)
Krogh, F. T.
1987-01-01
Initial-value ordinary differential equation solution via variable order Adams method (SIVA/DIVA) package is collection of subroutines for solution of nonstiff ordinary differential equations. There are versions for single-precision and double-precision arithmetic. Requires fewer evaluations of derivatives than other variable-order Adams predictor/ corrector methods. Option for direct integration of second-order equations makes integration of trajectory problems significantly more efficient. Written in FORTRAN 77.
Television Tracker Range Equation
NASA Astrophysics Data System (ADS)
Huan-Wen, Zhu
1987-05-01
The paper gives an approximate television tracker range equation based on the concept of the radiology and signal-to-noise of television system, and describes the physical process and mathematical method of reckoning range equation. The range equation is useful to the desing and development of a system. This paper also discusses the demand and selection standard of the television tracker system to the imaging device and gives some possible approaches to increase the range.
Rubel's universal differential equation
Duffin, R. J.
1981-01-01
Fourth-order differential equations such as 16y′my′2 - 32ymyny′ + 17y03 = 0 are developed. It is shown that the equation is “universal” in the sense that any continuous function can be approximated with arbitrary accuracy over the whole x axis by a solution y(x) of the equation. This solution is a piecewise polynomial of degree 9 and of class C4. PMID:16593068
Hyperbolic type transport equations
NASA Astrophysics Data System (ADS)
García-Colín, L. S.; Olivares-Robles, M. A.
1995-02-01
In recent years hyperbolic type transport equations have acquired a great deal of importance in problems ranging from theoretical physics to biology. In spite of their greater mathematical difficulty as compared with their parabolic type analogs arising from the framework of Linear Irreversible Thermodynamics, they have, in many ways, superseded the latter ones. Although the use of this type of equations is well known since the last century through the telegraphist equation of electromagnetic theory, their use in studying several problems in transport theory is hardly fifty years old. In fact the first appearance of a hyperbolic type transport equation for the problem of heat conduction dates back to Cattaneos' work in 1948. Three years later, in 1951 S. Goldstein showed how in the theory of stochastic processes this type of an equation is obtained in the continuous limit of a one-dimensional persistent random walk problem. After that, other phenomenological derivations have been offered for such equations. The main purpose of this paper is to critically discuss a derivation of a hyperbolic type Fokker-Planck equation recently presented using the same ideas as M.S. Green did in 1952 to provide the stochastic foundations of irreversible statistical mechanics. Arguments are given to show that such an equation as well as transport equations derived from it by taking appropriate averages are at most approximate and that a much more detailed analysis is required before asserting their validity.
Linear Equations: Equivalence = Success
ERIC Educational Resources Information Center
Baratta, Wendy
2011-01-01
The ability to solve linear equations sets students up for success in many areas of mathematics and other disciplines requiring formula manipulations. There are many reasons why solving linear equations is a challenging skill for students to master. One major barrier for students is the inability to interpret the equals sign as anything other than…
Yagi, M.; Horton, W. )
1994-07-01
A set of reduced Braginskii equations is derived without assuming flute ordering and the Boussinesq approximation. These model equations conserve the physical energy. It is crucial at finite [beta] that the perpendicular component of Ohm's law be solved to ensure [del][center dot][bold j]=0 for energy conservation.
Uniqueness of Maxwell's Equations.
ERIC Educational Resources Information Center
Cohn, Jack
1978-01-01
Shows that, as a consequence of two feasible assumptions and when due attention is given to the definition of charge and the fields E and B, the lowest-order equations that these two fields must satisfy are Maxwell's equations. (Author/GA)
Yagi, M.; Horton, W.
1993-11-01
A set of reduced Braginskii equations is derived without assuming flute ordering and the Boussinesq approximation. These model equations conserve the physical energy. It is crucial at finite {beta} that we solve the perpendicular component of Ohm`s law to conserve the physical energy while ensuring the relation {del} {center_dot} j = 0.
NASA Astrophysics Data System (ADS)
Shabat, A. B.
2016-12-01
We consider the class of entire functions of exponential type in relation to the scattering theory for the Schrödinger equation with a finite potential that is a finite Borel measure. These functions have a special self-similarity and satisfy q-difference functional equations. We study their asymptotic behavior and the distribution of zeros.
Uniqueness of Maxwell's Equations.
ERIC Educational Resources Information Center
Cohn, Jack
1978-01-01
Shows that, as a consequence of two feasible assumptions and when due attention is given to the definition of charge and the fields E and B, the lowest-order equations that these two fields must satisfy are Maxwell's equations. (Author/GA)
Angeles-Agdeppa, Imelda; Atmarita, Atmarita; Gironella, Glen M; Muslimatun, Siti; Carriquiry, Alicia
2016-01-01
Background: Vitamin A deficiency continues to be a major public health problem affecting developing countries where people eat mostly rice as a staple food. In Asia, rice provides up to 80% of the total daily energy intake. Objective: We used existing data sets from Bangladesh, Indonesia, and the Philippines, where dietary intakes have been quantified at the individual level to 1) determine the rice and vitamin A intake in nonpregnant, nonlactating women of reproductive age and in nonbreastfed children 1–3 y old and 2) simulate the amount of change that could be achieved in the prevalence of inadequate intake of vitamin A if rice biofortified with β-carotene were consumed instead of the rice consumed at present. Design: We considered a range of 4–20 parts per million (ppm) of β-carotene content and 10–70% substitution levels for the biofortified rice. Software was used to estimate usual rice and vitamin A intake for the simulation analyses. Results: In an analysis by country, the substitution of biofortified rice for white rice in the optimistic scenario (20 ppm and 70% substitution) decreased the prevalence of vitamin A inadequacy from baseline 78% in women and 71% in children in Bangladesh. In Indonesia and the Philippines, the prevalence of inadequacy fell by 55–60% in women and dropped by nearly 30% in children from baseline. Conclusions: The results of the simulation analysis were striking in that even low substitution levels and modest increases in the β-carotene of rice produced a meaningful decrease in the prevalence of inadequate intake of vitamin A. Increasing the substitution levels had a greater impact than increasing the β-carotene content by >12 ppm. PMID:27510534
De Moura, Fabiana F; Moursi, Mourad; Donahue Angel, Moira; Angeles-Agdeppa, Imelda; Atmarita, Atmarita; Gironella, Glen M; Muslimatun, Siti; Carriquiry, Alicia
2016-09-01
Vitamin A deficiency continues to be a major public health problem affecting developing countries where people eat mostly rice as a staple food. In Asia, rice provides up to 80% of the total daily energy intake. We used existing data sets from Bangladesh, Indonesia, and the Philippines, where dietary intakes have been quantified at the individual level to 1) determine the rice and vitamin A intake in nonpregnant, nonlactating women of reproductive age and in nonbreastfed children 1-3 y old and 2) simulate the amount of change that could be achieved in the prevalence of inadequate intake of vitamin A if rice biofortified with β-carotene were consumed instead of the rice consumed at present. We considered a range of 4-20 parts per million (ppm) of β-carotene content and 10-70% substitution levels for the biofortified rice. Software was used to estimate usual rice and vitamin A intake for the simulation analyses. In an analysis by country, the substitution of biofortified rice for white rice in the optimistic scenario (20 ppm and 70% substitution) decreased the prevalence of vitamin A inadequacy from baseline 78% in women and 71% in children in Bangladesh. In Indonesia and the Philippines, the prevalence of inadequacy fell by 55-60% in women and dropped by nearly 30% in children from baseline. The results of the simulation analysis were striking in that even low substitution levels and modest increases in the β-carotene of rice produced a meaningful decrease in the prevalence of inadequate intake of vitamin A. Increasing the substitution levels had a greater impact than increasing the β-carotene content by >12 ppm.
White, R D; Ness, K F; Robson, R E; Li, B
1999-08-01
A multiterm solution of the Boltzmann equation has been developed and used to calculate transport coefficients of charged-particle swarms in gases under the influence of electric and magnetic fields crossed at arbitrary angles psi. The hierarchy resulting from a spherical harmonic decomposition of the Boltzmann equation in the hydrodynamic regime [Ness, Phys. Rev. A 47, 327 (1993)] is solved numerically by representing the speed dependence of the phase-space distribution function in terms of an expansion in Sonine polynomials about a weighted sum of Maxwellian distributions at different temperatures. Results are given for charged-particle swarms in certain model gases over a range of psi and field strengths. The variation of the transport coefficients with psi is addressed using physical arguments. The errors associated with the two-term approximation and inadequacies of Legendre polynomial expansions are highlighted.
NASA Technical Reports Server (NTRS)
Thangam, S.; Speziale, C. G.
1991-01-01
The ability of two-equation models to accurately predict separated flows is analyzed from a combined theoretical and computational standpoint. Turbulent flow past a backward facing step is chosen as a test case in an effort to resolve the variety of conflicting results that were published during the past decade concerning the performance of two-equation models. It is found that the errors in the reported predictions of the k-epsilon model have two major origins: (1) numerical problems arising from inadequate resolution, and (2) inaccurate predictions for normal Reynolds stress differences arising from the use of an isotropic eddy viscosity. Inadequacies in near wall modelling play a substantially smaller role. Detailed calculations are presented which strongly indicate the standard k-epsilon model - when modified with an independently calibrated anisotropic eddy viscosity - can yield surprisingly good predictions for the backstep problem.
NASA Astrophysics Data System (ADS)
Kuksin, Sergei; Maiocchi, Alberto
In this chapter we present a general method of constructing the effective equation which describes the behavior of small-amplitude solutions for a nonlinear PDE in finite volume, provided that the linear part of the equation is a hamiltonian system with a pure imaginary discrete spectrum. The effective equation is obtained by retaining only the resonant terms of the nonlinearity (which may be hamiltonian, or may be not); the assertion that it describes the limiting behavior of small-amplitude solutions is a rigorous mathematical theorem. In particular, the method applies to the three- and four-wave systems. We demonstrate that different possible types of energy transport are covered by this method, depending on whether the set of resonances splits into finite clusters (this happens, e.g. in case of the Charney-Hasegawa-Mima equation), or is connected (this happens, e.g. in the case of the NLS equation if the space-dimension is at least two). For equations of the first type the energy transition to high frequencies does not hold, while for equations of the second type it may take place. Our method applies to various weakly nonlinear wave systems, appearing in plasma, meteorology and oceanography.
Nonlinear gyrokinetic equations
Dubin, D.H.E.; Krommes, J.A.; Oberman, C.; Lee, W.W.
1983-03-01
Nonlinear gyrokinetic equations are derived from a systematic Hamiltonian theory. The derivation employs Lie transforms and a noncanonical perturbation theory first used by Littlejohn for the simpler problem of asymptotically small gyroradius. For definiteness, we emphasize the limit of electrostatic fluctuations in slab geometry; however, there is a straight-forward generalization to arbitrary field geometry and electromagnetic perturbations. An energy invariant for the nonlinear system is derived, and various of its limits are considered. The weak turbulence theory of the equations is examined. In particular, the wave kinetic equation of Galeev and Sagdeev is derived from an asystematic truncation of the equations, implying that this equation fails to consider all gyrokinetic effects. The equations are simplified for the case of small but finite gyroradius and put in a form suitable for efficient computer simulation. Although it is possible to derive the Terry-Horton and Hasegawa-Mima equations as limiting cases of our theory, several new nonlinear terms absent from conventional theories appear and are discussed.
The Quadrature Master Equations
NASA Astrophysics Data System (ADS)
Hassan, N. J.; Pourdarvish, A.; Sadeghi, J.; Olaomi, J. O.
2017-04-01
In this paper, we derive the non-Markovian stochastic equation of motion (SEM) and master equations (MEs) for the open quantum system by using the non-Markovian stochastic Schrödinger equations (SSEs) for the quadrature unraveling in linear and nonlinear cases. The SSEs for quadrature unraveling arise as a special case of a quantum system. Also we derive the Markovian SEM and ME by using linear and nonlinear Itô SSEs for the measurement probabilities. In linear non-Markovian case, we calculate the convolutionless linear quadrature non-Markovian SEM and ME. We take advantage from example and show that corresponding theory.
Nonlinear ordinary difference equations
NASA Technical Reports Server (NTRS)
Caughey, T. K.
1979-01-01
Future space vehicles will be relatively large and flexible, and active control will be necessary to maintain geometrical configuration. While the stresses and strains in these space vehicles are not expected to be excessively large, their cumulative effects will cause significant geometrical nonlinearities to appear in the equations of motion, in addition to the nonlinearities caused by material properties. Since the only effective tool for the analysis of such large complex structures is the digital computer, it will be necessary to gain a better understanding of the nonlinear ordinary difference equations which result from the time discretization of the semidiscrete equations of motion for such structures.
A Comparison of IRT Equating and Beta 4 Equating.
ERIC Educational Resources Information Center
Kim, Dong-In; Brennan, Robert; Kolen, Michael
Four equating methods were compared using four equating criteria: first-order equity (FOE), second-order equity (SOE), conditional mean squared error (CMSE) difference, and the equipercentile equating property. The four methods were: (1) three parameter logistic (3PL) model true score equating; (2) 3PL observed score equating; (3) beta 4 true…
Concerning the equation of state for partially ionized system
Baker, Jr, George A
2008-01-01
I will discuss the expansion of various thermodynamic quantities about the ideal gas in powers of the electric charge, and I will discuss some cellular models. The first type of cellular model is appropriate for hydrogen. The second type is for Z > 1. It has the independent electron approximation within the atoms. These models are cross compared and minimal regions of validity are determined. The actual region of validity is expected to be larger. In the cellular models, the phase boundaries for liquid-gas transitions are found. For the second type of cellular model, in the part of the low-temperature, low-density region where there is not much expectation of validity of these methods, a non-thermodynamic region is found. I have devised a construction, similar in spirit to the Maxwell construction, to bridge this region so as to leave a thermodynamically valid equation of state. The non-thermodynamic region does not occur in hydrogen and it seems to be due to the inadequacy of the aforementioned approximation in that region.
Regularized Structural Equation Modeling.
Jacobucci, Ross; Grimm, Kevin J; McArdle, John J
A new method is proposed that extends the use of regularization in both lasso and ridge regression to structural equation models. The method is termed regularized structural equation modeling (RegSEM). RegSEM penalizes specific parameters in structural equation models, with the goal of creating easier to understand and simpler models. Although regularization has gained wide adoption in regression, very little has transferred to models with latent variables. By adding penalties to specific parameters in a structural equation model, researchers have a high level of flexibility in reducing model complexity, overcoming poor fitting models, and the creation of models that are more likely to generalize to new samples. The proposed method was evaluated through a simulation study, two illustrative examples involving a measurement model, and one empirical example involving the structural part of the model to demonstrate RegSEM's utility.
Nonlinear differential equations
Dresner, L.
1988-01-01
This report is the text of a graduate course on nonlinear differential equations given by the author at the University of Wisconsin-Madison during the summer of 1987. The topics covered are: direction fields of first-order differential equations; the Lie (group) theory of ordinary differential equations; similarity solutions of second-order partial differential equations; maximum principles and differential inequalities; monotone operators and iteration; complementary variational principles; and stability of numerical methods. The report should be of interest to graduate students, faculty, and practicing scientists and engineers. No prior knowledge is required beyond a good working knowledge of the calculus. The emphasis is on practical results. Most of the illustrative examples are taken from the fields of nonlinear diffusion, heat and mass transfer, applied superconductivity, and helium cryogenics.
Equations For Rotary Transformers
NASA Technical Reports Server (NTRS)
Salomon, Phil M.; Wiktor, Peter J.; Marchetto, Carl A.
1988-01-01
Equations derived for input impedance, input power, and ratio of secondary current to primary current of rotary transformer. Used for quick analysis of transformer designs. Circuit model commonly used in textbooks on theory of ac circuits.
ERIC Educational Resources Information Center
Shumway, Richard J.
1989-01-01
Illustrated is the problem of solving equations and some different strategies students might employ when using available technology. Gives illustrations for: exact solutions, approximate solutions, and approximate solutions which are graphically generated. (RT)
Discrete wave equation upscaling
NASA Astrophysics Data System (ADS)
Fichtner, Andreas; Hanasoge, Shravan M.
2017-01-01
We present homogenisation technique for the uniformly discretised wave equation, based on the derivation of an effective equation for the low-wavenumber component of the solution. The method produces a down-sampled, effective medium, thus making the solution of the effective equation less computationally expensive. Advantages of the method include its conceptual simplicity and ease of implementation, the applicability to any uniformly discretised wave equation in one, two or three dimensions, and the absence of any constraints on the medium properties. We illustrate our method with a numerical example of wave propagation through a one-dimensional multiscale medium, and demonstrate the accurate reproduction of the original wavefield for sufficiently low frequencies.
SIMULTANEOUS DIFFERENTIAL EQUATION COMPUTER
Collier, D.M.; Meeks, L.A.; Palmer, J.P.
1960-05-10
A description is given for an electronic simulator for a system of simultaneous differential equations, including nonlinear equations. As a specific example, a homogeneous nuclear reactor system including a reactor fluid, heat exchanger, and a steam boiler may be simulated, with the nonlinearity resulting from a consideration of temperature effects taken into account. The simulator includes three operational amplifiers, a multiplier, appropriate potential sources, and interconnecting R-C networks.
Relativistic Guiding Center Equations
White, R. B.; Gobbin, M.
2014-10-01
In toroidal fusion devices it is relatively easy that electrons achieve relativistic velocities, so to simulate runaway electrons and other high energy phenomena a nonrelativistic guiding center formalism is not sufficient. Relativistic guiding center equations including flute mode time dependent field perturbations are derived. The same variables as used in a previous nonrelativistic guiding center code are adopted, so that a straightforward modifications of those equations can produce a relativistic version.
Ritchie, A B; Crenshaw, M E
2004-09-17
Although the concept of the photon as a quantum particle is sharpened by the quantization of the energy of the classical radiation field in a cavity, the photon's spin has remained a classical degree of freedom. The photon is considered a spin-1 particle, although only two classical polarization states transverse to its direction of propagation are allowed. Effectively therefore the photon is a spin-1/2 particle, although it still obeys Bose-Einstein statistics because the photon-photon interaction is zero. Here they show that the two polarization states of the photon can be quantized using Pauli's spin vector, such that a suitable equation of motion for the photon is Dirac's relativistic wave equation for zero mass and zero charge. Maxwell's equations for a free photon are inferred from the Dirac-field formalism and thus provide proof of this claim. For photons in the presence of electronic sources for electromagnetic fields we posit Lorentz-invariant inhomogeneous photonic equations of motion. Electro-dynamic operator equations are inferred from this modified Dirac-field formalism which reduce to Maxwell's equations if spin-dependent terms in the radiation-matter interaction are dropped.
The Bernoulli-Poiseuille Equation.
ERIC Educational Resources Information Center
Badeer, Henry S.; Synolakis, Costas E.
1989-01-01
Describes Bernoulli's equation and Poiseuille's equation for fluid dynamics. Discusses the application of the combined Bernoulli-Poiseuille equation in real flows, such as viscous flows under gravity and acceleration. (YP)
The Bernoulli-Poiseuille Equation.
ERIC Educational Resources Information Center
Badeer, Henry S.; Synolakis, Costas E.
1989-01-01
Describes Bernoulli's equation and Poiseuille's equation for fluid dynamics. Discusses the application of the combined Bernoulli-Poiseuille equation in real flows, such as viscous flows under gravity and acceleration. (YP)
Spatial equation for water waves
NASA Astrophysics Data System (ADS)
Dyachenko, A. I.; Zakharov, V. E.
2016-02-01
A compact spatial Hamiltonian equation for gravity waves on deep water has been derived. The equation is dynamical and can describe extreme waves. The equation for the envelope of a wave train has also been obtained.
Introducing Chemical Formulae and Equations.
ERIC Educational Resources Information Center
Dawson, Chris; Rowell, Jack
1979-01-01
Discusses when the writing of chemical formula and equations can be introduced in the school science curriculum. Also presents ways in which formulae and equations learning can be aided and some examples for balancing and interpreting equations. (HM)
Budini, Adrian A.
2006-11-15
In this paper we derive an extra class of non-Markovian master equations where the system state is written as a sum of auxiliary matrixes whose evolution involve Lindblad contributions with local coupling between all of them, resembling the structure of a classical rate equation. The system dynamics may develop strong nonlocal effects such as the dependence of the stationary properties with the system initialization. These equations are derived from alternative microscopic interactions, such as complex environments described in a generalized Born-Markov approximation and tripartite system-environment interactions, where extra unobserved degrees of freedom mediates the entanglement between the system and a Markovian reservoir. Conditions that guarantee the completely positive condition of the solution map are found. Quantum stochastic processes that recover the system dynamics in average are formulated. We exemplify our results by analyzing the dynamical action of nontrivial structured dephasing and depolarizing reservoirs over a single qubit.
Parallel tridiagonal equation solvers
NASA Technical Reports Server (NTRS)
Stone, H. S.
1974-01-01
Three parallel algorithms were compared for the direct solution of tridiagonal linear systems of equations. The algorithms are suitable for computers such as ILLIAC 4 and CDC STAR. For array computers similar to ILLIAC 4, cyclic odd-even reduction has the least operation count for highly structured sets of equations, and recursive doubling has the least count for relatively unstructured sets of equations. Since the difference in operation counts for these two algorithms is not substantial, their relative running times may be more related to overhead operations, which are not measured in this paper. The third algorithm, based on Buneman's Poisson solver, has more arithmetic operations than the others, and appears to be the least favorable. For pipeline computers similar to CDC STAR, cyclic odd-even reduction appears to be the most preferable algorithm for all cases.
Nonlocal electrical diffusion equation
NASA Astrophysics Data System (ADS)
Gómez-Aguilar, J. F.; Escobar-Jiménez, R. F.; Olivares-Peregrino, V. H.; Benavides-Cruz, M.; Calderón-Ramón, C.
2016-07-01
In this paper, we present an analysis and modeling of the electrical diffusion equation using the fractional calculus approach. This alternative representation for the current density is expressed in terms of the Caputo derivatives, the order for the space domain is 0<β≤1 and for the time domain is 0<γ≤2. We present solutions for the full fractional equation involving space and time fractional derivatives using numerical methods based on Fourier variable separation. The case with spatial fractional derivatives leads to Levy flight type phenomena, while the time fractional equation is related to sub- or super diffusion. We show that the mathematical concept of fractional derivatives can be useful to understand the behavior of semiconductors, the design of solar panels, electrochemical phenomena and the description of anomalous complex processes.
Obtaining Maxwell's equations heuristically
NASA Astrophysics Data System (ADS)
Diener, Gerhard; Weissbarth, Jürgen; Grossmann, Frank; Schmidt, Rüdiger
2013-02-01
Starting from the experimental fact that a moving charge experiences the Lorentz force and applying the fundamental principles of simplicity (first order derivatives only) and linearity (superposition principle), we show that the structure of the microscopic Maxwell equations for the electromagnetic fields can be deduced heuristically by using the transformation properties of the fields under space inversion and time reversal. Using the experimental facts of charge conservation and that electromagnetic waves propagate with the speed of light, together with Galilean invariance of the Lorentz force, allows us to finalize Maxwell's equations and to introduce arbitrary electrodynamics units naturally.
NASA Technical Reports Server (NTRS)
Markley, F. Landis
1995-01-01
Kepler's Equation is solved over the entire range of elliptic motion by a fifth-order refinement of the solution of a cubic equation. This method is not iterative, and requires only four transcendental function evaluations: a square root, a cube root, and two trigonometric functions. The maximum relative error of the algorithm is less than one part in 10(exp 18), exceeding the capability of double-precision computer arithmetic. Roundoff errors in double-precision implementation of the algorithm are addressed, and procedures to avoid them are developed.
Stochastic differential equations
Sobczyk, K. )
1990-01-01
This book provides a unified treatment of both regular (or random) and Ito stochastic differential equations. It focuses on solution methods, including some developed only recently. Applications are discussed, in particular an insight is given into both the mathematical structure, and the most efficient solution methods (analytical as well as numerical). Starting from basic notions and results of the theory of stochastic processes and stochastic calculus (including Ito's stochastic integral), many principal mathematical problems and results related to stochastic differential equations are expounded here for the first time. Applications treated include those relating to road vehicles, earthquake excitations and offshore structures.
Ordinary Differential Equations
NASA Astrophysics Data System (ADS)
Britz, Dieter
In this chapter, the numerical solution of ordinary differential equations (odes) will be described. There is a direct connection between this area and that of partial differential equations (pdes), as noted in, for example [558]. The ode field is large; but here we restrict ourselves to those techniques that appear again in the pde field. Readers wishing greater depth than is presented here can find it in the great number of texts on the subject, such as the classics by Lapidus & Seinfeld [351], Gear [264] or Jain [314];there is a very clear chapter in Gerald [266].
Accumulative Equating Error after a Chain of Linear Equatings
ERIC Educational Resources Information Center
Guo, Hongwen
2010-01-01
After many equatings have been conducted in a testing program, equating errors can accumulate to a degree that is not negligible compared to the standard error of measurement. In this paper, the author investigates the asymptotic accumulative standard error of equating (ASEE) for linear equating methods, including chained linear, Tucker, and…
Comparison of Kernel Equating and Item Response Theory Equating Methods
ERIC Educational Resources Information Center
Meng, Yu
2012-01-01
The kernel method of test equating is a unified approach to test equating with some advantages over traditional equating methods. Therefore, it is important to evaluate in a comprehensive way the usefulness and appropriateness of the Kernel equating (KE) method, as well as its advantages and disadvantages compared with several popular item…
Comparison of Kernel Equating and Item Response Theory Equating Methods
ERIC Educational Resources Information Center
Meng, Yu
2012-01-01
The kernel method of test equating is a unified approach to test equating with some advantages over traditional equating methods. Therefore, it is important to evaluate in a comprehensive way the usefulness and appropriateness of the Kernel equating (KE) method, as well as its advantages and disadvantages compared with several popular item…
The Statistical Drake Equation
NASA Astrophysics Data System (ADS)
Maccone, Claudio
2010-12-01
We provide the statistical generalization of the Drake equation. From a simple product of seven positive numbers, the Drake equation is now turned into the product of seven positive random variables. We call this "the Statistical Drake Equation". The mathematical consequences of this transformation are then derived. The proof of our results is based on the Central Limit Theorem (CLT) of Statistics. In loose terms, the CLT states that the sum of any number of independent random variables, each of which may be ARBITRARILY distributed, approaches a Gaussian (i.e. normal) random variable. This is called the Lyapunov Form of the CLT, or the Lindeberg Form of the CLT, depending on the mathematical constraints assumed on the third moments of the various probability distributions. In conclusion, we show that: The new random variable N, yielding the number of communicating civilizations in the Galaxy, follows the LOGNORMAL distribution. Then, as a consequence, the mean value of this lognormal distribution is the ordinary N in the Drake equation. The standard deviation, mode, and all the moments of this lognormal N are also found. The seven factors in the ordinary Drake equation now become seven positive random variables. The probability distribution of each random variable may be ARBITRARY. The CLT in the so-called Lyapunov or Lindeberg forms (that both do not assume the factors to be identically distributed) allows for that. In other words, the CLT "translates" into our statistical Drake equation by allowing an arbitrary probability distribution for each factor. This is both physically realistic and practically very useful, of course. An application of our statistical Drake equation then follows. The (average) DISTANCE between any two neighboring and communicating civilizations in the Galaxy may be shown to be inversely proportional to the cubic root of N. Then, in our approach, this distance becomes a new random variable. We derive the relevant probability density
ERIC Educational Resources Information Center
Fay, Temple H.
2010-01-01
Through numerical investigations, we study examples of the forced quadratic spring equation [image omitted]. By performing trial-and-error numerical experiments, we demonstrate the existence of stability boundaries in the phase plane indicating initial conditions yielding bounded solutions, investigate the resonance boundary in the [omega]…
Structural Equation Model Trees
ERIC Educational Resources Information Center
Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman
2013-01-01
In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…
ERIC Educational Resources Information Center
Savoy, L. G.
1988-01-01
Describes a study of students' ability to balance equations. Answers to a test on this topic were analyzed to determine the level of understanding and processes used by the students. Presented is a method to teach this skill to high school chemistry students. (CW)
Do Differential Equations Swing?
ERIC Educational Resources Information Center
Maruszewski, Richard F., Jr.
2006-01-01
One of the units of in a standard differential equations course is a discussion of the oscillatory motion of a spring and the associated material on forcing functions and resonance. During the presentation on practical resonance, the instructor may tell students that it is similar to when they take their siblings to the playground and help them on…
Modelling by Differential Equations
ERIC Educational Resources Information Center
Chaachoua, Hamid; Saglam, Ayse
2006-01-01
This paper aims to show the close relation between physics and mathematics taking into account especially the theory of differential equations. By analysing the problems posed by scientists in the seventeenth century, we note that physics is very important for the emergence of this theory. Taking into account this analysis, we show the…
Lawrence A. Soltis
1999-01-01
Equations for deformation and stress, which are the basis for tension members and beam and column design, are discussed in this chapter. The first two sections cover tapered members, straight members, and special considerations such as notches, slits, and size effect. A third section presents stability criteria for members subject to buckling and for members subject to...
NASA Astrophysics Data System (ADS)
Mejjaoli, Hatem
2008-12-01
We introduce and study the Dunkl symmetric systems. We prove the well-posedness results for the Cauchy problem for these systems. Eventually we describe the finite speed of it. Next the semi-linear Dunkl-wave equations are also studied.
Modelling by Differential Equations
ERIC Educational Resources Information Center
Chaachoua, Hamid; Saglam, Ayse
2006-01-01
This paper aims to show the close relation between physics and mathematics taking into account especially the theory of differential equations. By analysing the problems posed by scientists in the seventeenth century, we note that physics is very important for the emergence of this theory. Taking into account this analysis, we show the…
Structural Equation Model Trees
ERIC Educational Resources Information Center
Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman
2013-01-01
In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree…
Equating Practical Examinations.
ERIC Educational Resources Information Center
Lunz, Mary E.; And Others
This paper describes and illustrates a method for equating examinations with multiple facets (i.e., items, examinees, judges, tasks, and rating scales). The data are from the practical section of two histotechnology certification examinations. The first practical examination involved 210 examinees, 14 judges, 15 slides, 3 tasks, and 2 rating…
Douglas R. Rammer
2010-01-01
Equations for deformation and stress, which are the basis for tension members and beam and column design, are discussed in this chapter. The first two sections cover tapered members, straight members, and special considerations such as notches, slits, and size effect. A third section presents stability criteria for members subject to buckling and for members subject to...
Generalized reduced magnetohydrodynamic equations
Kruger, S.E.
1999-02-01
A new derivation of reduced magnetohydrodynamic (MHD) equations is presented. A multiple-time-scale expansion is employed. It has the advantage of clearly separating the three time scales of the problem associated with (1) MHD equilibrium, (2) fluctuations whose wave vector is aligned perpendicular to the magnetic field, and (3) those aligned parallel to the magnetic field. The derivation is carried out without relying on a large aspect ratio assumption; therefore this model can be applied to any general configuration. By accounting for the MHD equilibrium and constraints to eliminate the fast perpendicular waves, equations are derived to evolve scalar potential quantities on a time scale associated with the parallel wave vector (shear-Alfven wave time scale), which is the time scale of interest for MHD instability studies. Careful attention is given in the derivation to satisfy energy conservation and to have manifestly divergence-free magnetic fields to all orders in the expansion parameter. Additionally, neoclassical closures and equilibrium shear flow effects are easily accounted for in this model. Equations for the inner resistive layer are derived which reproduce the linear ideal and resistive stability criterion of Glasser, Greene, and Johnson. The equations have been programmed into a spectral initial value code and run with shear flow that is consistent with the equilibrium input into the code. Linear results of tearing modes with shear flow are presented which differentiate the effects of shear flow gradients in the layer with the effects of the shear flow decoupling multiple harmonics.
Parallel Multigrid Equation Solver
Adams, Mark
2001-09-07
Prometheus is a fully parallel multigrid equation solver for matrices that arise in unstructured grid finite element applications. It includes a geometric and an algebraic multigrid method and has solved problems of up to 76 mullion degrees of feedom, problems in linear elasticity on the ASCI blue pacific and ASCI red machines.
Quenching equation for scintillation
NASA Astrophysics Data System (ADS)
Kato, Takahisa
1980-06-01
A mathematical expression is postulated showing the relationship between counting rate and quenching agent concentration in a liquid scintillation solution. The expression is more suited to a wider range of quenching agent concentrations than the Stern-Volmer equation. An estimation of the quenched correction is demonstrated using the expression.
Stochastic Hodgkin-Huxley equations with colored noise terms in the conductances.
Güler, Marifi
2013-01-01
The excitability of cells is facilitated by voltage-gated ion channels. These channels accommodate a multiple number of gates individually. The possible impact of that gate multiplicity on the cell's function, specifically when the membrane area is of limited size, was investigated in the author's prior work (Güler, 2011 ). There, it was found that a nontrivially persistent correlation takes place between the transmembrane voltage fluctuations (also between the fluctuations in the gating variables) and the component of open channel fluctuations attributed to the gate multiplicity. This nontrivial phenomenon was found to be playing a major augmentative role for the elevation of excitability and spontaneous firing in small cells. In addition, the same phenomenon was found to be enhancing spike coherence significantly. Here we extend Fox and Lu's ( 1994 ) stochastic Hodgkin-Huxley equations by incorporating colored noise terms into the conductances there to obtain a formalism capable of capturing the addressed cross-correlations. Statistics of spike generation, spike coherence, firing efficiency, latency, and jitter from the articulated set of equations are found to be highly accurate in comparison with the corresponding statistics from the exact microscopic Markov simulations. This way, it is demonstrated vividly that our formulation overcomes the inherent inadequacy of the Fox and Lu equations. Finally, a recently proposed diffusion approximation method (Linaro, Storace, & Giugliano, 2011 ) is taken into consideration, and a discussion on its character is pursued.
Faria, Franciane Rocha; Faria, Eliane Rodrigues; Cecon, Roberta Stofeles; Barbosa Júnior, Djalma Adão; Franceschini, Sylvia do Carmo Castro; Peluzio, Maria do Carmo Gouveia; Ribeiro, Andréia Queiroz; Lira, Pedro Israel Cabral; Cecon, Paulo Roberto; Priore, Silvia Eloiza
2013-01-01
The aim of this study was to analyze body fat anthropometric equations and electrical bioimpedance analysis (BIA) in the prediction of cardiovascular risk factors in eutrophic and overweight adolescents. 210 adolescents were divided into eutrophic group (G1) and overweight group (G2). The percentage of body fat (% BF) was estimated using 10 body fat anthropometric equations and 2 BIA. We measured lipid profiles, uric acid, insulin, fasting glucose, homeostasis model assessment-insulin resistance (HOMA-IR), and blood pressure. We found that 76.7% of the adolescents exhibited inadequacy of at least one biochemical parameter or clinical cardiovascular risk. Higher values of triglycerides (TG) (P = 0.001), insulin, and HOMA-IR (P < 0.001) were observed in the G2 adolescents. In multivariate linear regression analysis, the % BF from equation (5) was associated with TG, diastolic blood pressure, and insulin in G1. Among the G2 adolescents, the % BF estimated by (5) and (9) was associated with LDL, TG, insulin, and the HOMA-IR. Body fat anthropometric equations were associated with cardiovascular risk factors and should be used to assess the nutritional status of adolescents. In this study, equation (5) was associated with a higher number of cardiovascular risk factors independent of the nutritional status of adolescents. PMID:23762051
Nonlinear equations of 'variable type'
NASA Astrophysics Data System (ADS)
Larkin, N. A.; Novikov, V. A.; Ianenko, N. N.
In this monograph, new scientific results related to the theory of equations of 'variable type' are presented. Equations of 'variable type' are equations for which the original type is not preserved within the entire domain of coefficient definition. This part of the theory of differential equations with partial derivatives has been developed intensively in connection with the requirements of mechanics. The relations between equations of the considered type and the problems of mathematical physics are explored, taking into account quasi-linear equations, and models of mathematical physics which lead to equations of 'variable type'. Such models are related to transonic flows, problems involving a separation of the boundary layer, gasdynamics and the van der Waals equation, shock wave phenomena, and a combustion model with a turbulent diffusion flame. Attention is also given to nonlinear parabolic equations, and nonlinear partial differential equations of the third order.
Methods for Equating Mental Tests.
1984-11-01
1983) compared conventional and IRT methods for equating the Test of English as a Foreign Language ( TOEFL ) after chaining. Three conventional and...three IRT equating methods were examined in this study; two sections of TOEFL were each (separately) equated. The IRT methods included the following: (a...group. A separate base form was established for each of the six equating methods. Instead of equating the base-form TOEFL to itself, the last (eighth
Supersymmetric fifth order evolution equations
Tian, K.; Liu, Q. P.
2010-03-08
This paper considers supersymmetric fifth order evolution equations. Within the framework of symmetry approach, we give a list containing six equations, which are (potentially) integrable systems. Among these equations, the most interesting ones include a supersymmetric Sawada-Kotera equation and a novel supersymmetric fifth order KdV equation. For the latter, we supply some properties such as a Hamiltonian structures and a possible recursion operator.
Brownian motion from Boltzmann's equation.
NASA Technical Reports Server (NTRS)
Montgomery, D.
1971-01-01
Two apparently disparate lines of inquiry in kinetic theory are shown to be equivalent: (1) Brownian motion as treated by the (stochastic) Langevin equation and Fokker-Planck equation; and (2) Boltzmann's equation. The method is to derive the kinetic equation for Brownian motion from the Boltzmann equation for a two-component neutral gas by a simultaneous expansion in the density and mass ratios.
Flavored quantum Boltzmann equations
Cirigliano, Vincenzo; Lee, Christopher; Ramsey-Musolf, Michael J.; Tulin, Sean
2010-05-15
We derive from first principles, using nonequilibrium field theory, the quantum Boltzmann equations that describe the dynamics of flavor oscillations, collisions, and a time-dependent mass matrix in the early universe. Working to leading nontrivial order in ratios of relevant time scales, we study in detail a toy model for weak-scale baryogenesis: two scalar species that mix through a slowly varying time-dependent and CP-violating mass matrix, and interact with a thermal bath. This model clearly illustrates how the CP asymmetry arises through coherent flavor oscillations in a nontrivial background. We solve the Boltzmann equations numerically for the density matrices, investigating the impact of collisions in various regimes.
Perturbed nonlinear differential equations
NASA Technical Reports Server (NTRS)
Proctor, T. G.
1974-01-01
For perturbed nonlinear systems, a norm, other than the supremum norm, is introduced on some spaces of continuous functions. This makes possible the study of new types of behavior. A study is presented on a perturbed nonlinear differential equation defined on a half line, and the existence of a family of solutions with special boundedness properties is established. The ideas developed are applied to the study of integral manifolds, and examples are given.
NASA Astrophysics Data System (ADS)
Trzetrzelewski, Maciej
2016-11-01
Starting with a Nambu-Goto action, a Dirac-like equation can be constructed by taking the square-root of the momentum constraint. The eigenvalues of the resulting Hamiltonian are real and correspond to masses of the excited string. In particular there are no tachyons. A special case of radial oscillations of a closed string in Minkowski space-time admits exact solutions in terms of wave functions of the harmonic oscillator.
Quantum molecular master equations
NASA Astrophysics Data System (ADS)
Brechet, Sylvain D.; Reuse, Francois A.; Maschke, Klaus; Ansermet, Jean-Philippe
2016-10-01
We present the quantum master equations for midsize molecules in the presence of an external magnetic field. The Hamiltonian describing the dynamics of a molecule accounts for the molecular deformation and orientation properties, as well as for the electronic properties. In order to establish the master equations governing the relaxation of free-standing molecules, we have to split the molecule into two weakly interacting parts, a bath and a bathed system. The adequate choice of these systems depends on the specific physical system under consideration. Here we consider a first system consisting of the molecular deformation and orientation properties and the electronic spin properties and a second system composed of the remaining electronic spatial properties. If the characteristic time scale associated with the second system is small with respect to that of the first, the second may be considered as a bath for the first. Assuming that both systems are weakly coupled and initially weakly correlated, we obtain the corresponding master equations. They describe notably the relaxation of magnetic properties of midsize molecules, where the change of the statistical properties of the electronic orbitals is expected to be slow with respect to the evolution time scale of the bathed system.
Fractional Vorticity Equations
NASA Astrophysics Data System (ADS)
Schertzer, D.; Tchguirinskaia, I.; Lovejoy, S.; Tuck, A.
2012-04-01
As a result of a thorough discussion (Schertzer et al., Atmos. Chem. Phys., 12, 327-336, 2012 ) of the limitations of the quasi-geostrophic approximation and turbulence, fractional vorticity equations were obtained. This was done with the help of an anisotropic scaling analysis, instead of the classical scale analysis, as done to derive the quasi-geostrophic approximation. This breaks the rotational symmetry of the classical 3D vorticity equations and a priori yields a (2 + Hz)-dimensional turbulence (0 ≤ Hz ≤ 1). This corresponds to a first step in the derivation of a dynamical alternative to the quasi-geostrophic approximation and turbulence. The corresponding precise definition of fractional dimensional turbulence already demonstrates that the classical 2-D and 3-D turbulence are not the main options to understand atmospheric and oceanic dynamics. Although (2 + Hz)-dimensional turbulence (with 0 < Hz < 1) has more common features with 3-D turbulence than with 2-D turbulence, it has nevertheless very distinctive features: its scaling anisotropy is in agreement with the layered pancake structure, which is typical of rotating and stratified turbulence, but not of the classical 3-D turbulence. In this presentation, we further discuss the properties of this set of deterministic-like equations, especially how they can generate a statistical scaling anisotropy, as well as the relevance of the theoretical value Hz = 5/9.
NASA Astrophysics Data System (ADS)
Scherer, Philipp O. J.
We discuss several strategies for the time integration of first order initial value problems. The explicit Euler forward difference has low error order. The much more accurate symmetric difference quotient can be used as the corrector step in combination with an explicit Euler predictor step and is often used for the time integration of partial differential equations. Methods with higher error order can be obtained from a Taylor series expansion, like the Nordsieck and Gear predictor-corrector methods which have been often applied in molecular dynamics calculations. Runge-Kutta methods are very important for ordinary differential equations. They are robust and allow an adaptive control of the step size. Very accurate results can be obtained for ordinary differential equations with extrapolation methods like the famous Gragg-Bulirsch-Stör method. Multistep methods use information from several points. Best known are Adams-Bashforth-Moulton methods and Gear methods (also known as backward differentiation methods), which are especially useful for stiff problems. The class of Verlet methods has been developed for molecular dynamics calculations. These are symplectic and time reversible and conserve energy over long trajectories.
Double-Plate Penetration Equations
NASA Technical Reports Server (NTRS)
Hayashida, K. B.; Robinson, J. H.
2000-01-01
This report compares seven double-plate penetration predictor equations for accuracy and effectiveness of a shield design. Three of the seven are the Johnson Space Center original, modified, and new Cour-Palais equations. The other four are the Nysmith, Lundeberg-Stern-Bristow, Burch, and Wilkinson equations. These equations, except the Wilkinson equation, were derived from test results, with the velocities ranging up to 8 km/sec. Spreadsheet software calculated the projectile diameters for various velocities for the different equations. The results were plotted on projectile diameter versus velocity graphs for the expected orbital debris impact velocities ranging from 2 to 15 km/sec. The new Cour-Palais double-plate penetration equation was compared to the modified Cour-Palais single-plate penetration equation. Then the predictions from each of the seven double-plate penetration equations were compared to each other for a chosen shield design. Finally, these results from the equations were compared with test results performed at the NASA Marshall Space Flight Center. Because the different equations predict a wide range of projectile diameters at any given velocity, it is very difficult to choose the "right" prediction equation for shield configurations other than those exactly used in the equations' development. Although developed for various materials, the penetration equations alone cannot be relied upon to accurately predict the effectiveness of a shield without using hypervelocity impact tests to verify the design.
Computing generalized Langevin equations and generalized Fokker-Planck equations.
Darve, Eric; Solomon, Jose; Kia, Amirali
2009-07-07
The Mori-Zwanzig formalism is an effective tool to derive differential equations describing the evolution of a small number of resolved variables. In this paper we present its application to the derivation of generalized Langevin equations and generalized non-Markovian Fokker-Planck equations. We show how long time scales rates and metastable basins can be extracted from these equations. Numerical algorithms are proposed to discretize these equations. An important aspect is the numerical solution of the orthogonal dynamics equation which is a partial differential equation in a high dimensional space. We propose efficient numerical methods to solve this orthogonal dynamics equation. In addition, we present a projection formalism of the Mori-Zwanzig type that is applicable to discrete maps. Numerical applications are presented from the field of Hamiltonian systems.
Reduction operators of Burgers equation
Pocheketa, Oleksandr A.; Popovych, Roman O.
2013-01-01
The solution of the problem on reduction operators and nonclassical reductions of the Burgers equation is systematically treated and completed. A new proof of the theorem on the special “no-go” case of regular reduction operators is presented, and the representation of the coefficients of operators in terms of solutions of the initial equation is constructed for this case. All possible nonclassical reductions of the Burgers equation to single ordinary differential equations are exhaustively described. Any Lie reduction of the Burgers equation proves to be equivalent via the Hopf–Cole transformation to a parameterized family of Lie reductions of the linear heat equation. PMID:23576819
Reduction operators of Burgers equation.
Pocheketa, Oleksandr A; Popovych, Roman O
2013-02-01
The solution of the problem on reduction operators and nonclassical reductions of the Burgers equation is systematically treated and completed. A new proof of the theorem on the special "no-go" case of regular reduction operators is presented, and the representation of the coefficients of operators in terms of solutions of the initial equation is constructed for this case. All possible nonclassical reductions of the Burgers equation to single ordinary differential equations are exhaustively described. Any Lie reduction of the Burgers equation proves to be equivalent via the Hopf-Cole transformation to a parameterized family of Lie reductions of the linear heat equation.
Instructional Cost Analysis: History and Present Inadequacies.
ERIC Educational Resources Information Center
Humphrey, David A.
The cost analysis of instruction is conducted according to principles of teaching and learning that have often become historically dated. Using today's costing systems prevents determination of whether cost effectiveness actually exists. The patterns of instruction in higher education and the systems employed for instructional cost analysis are…
Evaluating Equating Results: Percent Relative Error for Chained Kernel Equating
ERIC Educational Resources Information Center
Jiang, Yanlin; von Davier, Alina A.; Chen, Haiwen
2012-01-01
This article presents a method for evaluating equating results. Within the kernel equating framework, the percent relative error (PRE) for chained equipercentile equating was computed under the nonequivalent groups with anchor test (NEAT) design. The method was applied to two data sets to obtain the PRE, which can be used to measure equating…
Differential Equations Compatible with Boundary Rational qKZ Equation
NASA Astrophysics Data System (ADS)
Takeyama, Yoshihiro
2011-10-01
We give diffierential equations compatible with the rational qKZ equation with boundary reflection. The total system contains the trigonometric degeneration of the bispectral qKZ equation of type (Cěen, Cn) which in the case of type GLn was studied by van Meer and Stokman. We construct an integral formula for solutions to our compatible system in a special case.
Evaluating Equating Results: Percent Relative Error for Chained Kernel Equating
ERIC Educational Resources Information Center
Jiang, Yanlin; von Davier, Alina A.; Chen, Haiwen
2012-01-01
This article presents a method for evaluating equating results. Within the kernel equating framework, the percent relative error (PRE) for chained equipercentile equating was computed under the nonequivalent groups with anchor test (NEAT) design. The method was applied to two data sets to obtain the PRE, which can be used to measure equating…
Makkonen, Lasse
2016-04-06
Young's construction for a contact angle at a three-phase intersection forms the basis of all fields of science that involve wetting and capillary action. We find compelling evidence from recent experimental results on the deformation of a soft solid at the contact line, and displacement of an elastic wire immersed in a liquid, that Young's equation can only be interpreted by surface energies, and not as a balance of surface tensions. It follows that the a priori variable in finding equilibrium is not the position of the contact line, but the contact angle. This finding provides the explanation for the pinning of a contact line.
The Arrhenius equation revisited.
Peleg, Micha; Normand, Mark D; Corradini, Maria G
2012-01-01
The Arrhenius equation has been widely used as a model of the temperature effect on the rate of chemical reactions and biological processes in foods. Since the model requires that the rate increase monotonically with temperature, its applicability to enzymatic reactions and microbial growth, which have optimal temperature, is obviously limited. This is also true for microbial inactivation and chemical reactions that only start at an elevated temperature, and for complex processes and reactions that do not follow fixed order kinetics, that is, where the isothermal rate constant, however defined, is a function of both temperature and time. The linearity of the Arrhenius plot, that is, Ln[k(T)] vs. 1/T where T is in °K has been traditionally considered evidence of the model's validity. Consequently, the slope of the plot has been used to calculate the reaction or processes' "energy of activation," usually without independent verification. Many experimental and simulated rate constant vs. temperature relationships that yield linear Arrhenius plots can also be described by the simpler exponential model Ln[k(T)/k(T(reference))] = c(T-T(reference)). The use of the exponential model or similar empirical alternative would eliminate the confusing temperature axis inversion, the unnecessary compression of the temperature scale, and the need for kinetic assumptions that are hard to affirm in food systems. It would also eliminate the reference to the Universal gas constant in systems where a "mole" cannot be clearly identified. Unless proven otherwise by independent experiments, one cannot dismiss the notion that the apparent linearity of the Arrhenius plot in many food systems is due to a mathematical property of the model's equation rather than to the existence of a temperature independent "energy of activation." If T+273.16°C in the Arrhenius model's equation is replaced by T+b, where the numerical value of the arbitrary constant b is substantially larger than T and T
Perturbed nonlinear differential equations
NASA Technical Reports Server (NTRS)
Proctor, T. G.
1972-01-01
The existence of a solution defined for all t and possessing a type of boundedness property is established for the perturbed nonlinear system y = f(t,y) + F(t,y). The unperturbed system x = f(t,x) has a dichotomy in which some solutions exist and are well behaved as t increases to infinity, and some solution exists and are well behaved as t decreases to minus infinity. A similar study is made for a perturbed nonlinear differential equation defined on a half line, R+, and the existence of a family of solutions with special boundedness properties is established. The ideas are applied to integral manifolds.
Problems, Perspectives, and Practical Issues in Equating.
ERIC Educational Resources Information Center
Weiss, David J., Ed.
1987-01-01
Issues concerning equating test scores are discussed in an introduction, four papers, and two commentaries. Equating methods research, sampling errors, linear equating, population differences, sources of equating errors, and a circular equating paradigm are considered. (SLD)
Noncommutativity and the Friedmann Equations
Sabido, M.; Socorro, J.; Guzman, W.
2010-07-12
In this paper we study noncommutative scalar field cosmology, we find the noncommutative Friedmann equations as well as the noncommutative Klein-Gordon equation, interestingly the noncommutative contributions are only present up to second order in the noncommutitive parameter.
Conservational PDF Equations of Turbulence
NASA Technical Reports Server (NTRS)
Shih, Tsan-Hsing; Liu, Nan-Suey
2010-01-01
Recently we have revisited the traditional probability density function (PDF) equations for the velocity and species in turbulent incompressible flows. They are all unclosed due to the appearance of various conditional means which are modeled empirically. However, we have observed that it is possible to establish a closed velocity PDF equation and a closed joint velocity and species PDF equation through conditions derived from the integral form of the Navier-Stokes equations. Although, in theory, the resulted PDF equations are neither general nor unique, they nevertheless lead to the exact transport equations for the first moment as well as all higher order moments. We refer these PDF equations as the conservational PDF equations. This observation is worth further exploration for its validity and CFD application
Shock wave structure using nonlinear model Boltzmann equations
NASA Technical Reports Server (NTRS)
Segal, Ben Maurice
1971-01-01
The structure of a strong plane shock wave in a monatomic rarefied perfect gas is one of the simplest problems able to be posed in kinetic theory, and one of the hardest to solve. Its simplicity lies in the absence of solid boundaries, geometrical complications, or internal molecular energy. Its difficulty arises from the great departure of the gas from equilibrium within the shock, which invalidates many of the techniques used successfully elsewhere in kinetic theory. In addition to this theoretical challenge, the modern development of ballistics and hypersonic flight has helped to stimulate extensive theoretical and experimental interest in the shock problem. The experimenters in turn have encountered great difficulties on account of the very small physical dimensions of shocks. In fact, until very recently indeed, any close comparisons of theoretical and experimental shock structure results have been rather unprofitable due to the inadequacies of both theory and experiment. During the last few years this situation has been appreciably improved by development of the Monte Carlo method. This allows idealized 'experiments' to be performed on large computers instead of in wind tunnels, using a known intermolecular force law. The most developed of these methods has been shown to be equivalent theoretically to the Boltzmann equation and to give results which agree extremely closely with measurements of high accuracy. Thus Monte Carlo results not only form the soundest basis for our present theoretical knowledge of shock wave structure, but, for purposes of developing other theories, can also be considered a very valuable experimental resource. However, such results remain very expensive to obtain. In this thesis we develop more economical kinetic theory methods for the approximate prediction of shock structure, and compare our results with those of the Monte Carlo method.
``Riemann equations'' in bidifferential calculus
NASA Astrophysics Data System (ADS)
Chvartatskyi, O.; Müller-Hoissen, F.; Stoilov, N.
2015-10-01
We consider equations that formally resemble a matrix Riemann (or Hopf) equation in the framework of bidifferential calculus. With different choices of a first-order bidifferential calculus, we obtain a variety of equations, including a semi-discrete and a fully discrete version of the matrix Riemann equation. A corresponding universal solution-generating method then either yields a (continuous or discrete) Cole-Hopf transformation, or leaves us with the problem of solving Riemann equations (hence an application of the hodograph method). If the bidifferential calculus extends to second order, solutions of a system of "Riemann equations" are also solutions of an equation that arises, on the universal level of bidifferential calculus, as an integrability condition. Depending on the choice of bidifferential calculus, the latter can represent a number of prominent integrable equations, like self-dual Yang-Mills, as well as matrix versions of the two-dimensional Toda lattice, Hirota's bilinear difference equation, (2+1)-dimensional Nonlinear Schrödinger (NLS), Kadomtsev-Petviashvili (KP) equation, and Davey-Stewartson equations. For all of them, a recent (non-isospectral) binary Darboux transformation result in bidifferential calculus applies, which can be specialized to generate solutions of the associated "Riemann equations." For the latter, we clarify the relation between these specialized binary Darboux transformations and the aforementioned solution-generating method. From (arbitrary size) matrix versions of the "Riemann equations" associated with an integrable equation, possessing a bidifferential calculus formulation, multi-soliton-type solutions of the latter can be generated. This includes "breaking" multi-soliton-type solutions of the self-dual Yang-Mills and the (2+1)-dimensional NLS equation, which are parametrized by solutions of Riemann equations.
The Forced Hard Spring Equation
ERIC Educational Resources Information Center
Fay, Temple H.
2006-01-01
Through numerical investigations, various examples of the Duffing type forced spring equation with epsilon positive, are studied. Since [epsilon] is positive, all solutions to the associated homogeneous equation are periodic and the same is true with the forcing applied. The damped equation exhibits steady state trajectories with the interesting…
Successfully Transitioning to Linear Equations
ERIC Educational Resources Information Center
Colton, Connie; Smith, Wendy M.
2014-01-01
The Common Core State Standards for Mathematics (CCSSI 2010) asks students in as early as fourth grade to solve word problems using equations with variables. Equations studied at this level generate a single solution, such as the equation x + 10 = 25. For students in fifth grade, the Common Core standard for algebraic thinking expects them to…
Solving Nonlinear Coupled Differential Equations
NASA Technical Reports Server (NTRS)
Mitchell, L.; David, J.
1986-01-01
Harmonic balance method developed to obtain approximate steady-state solutions for nonlinear coupled ordinary differential equations. Method usable with transfer matrices commonly used to analyze shaft systems. Solution to nonlinear equation, with periodic forcing function represented as sum of series similar to Fourier series but with form of terms suggested by equation itself.
Successfully Transitioning to Linear Equations
ERIC Educational Resources Information Center
Colton, Connie; Smith, Wendy M.
2014-01-01
The Common Core State Standards for Mathematics (CCSSI 2010) asks students in as early as fourth grade to solve word problems using equations with variables. Equations studied at this level generate a single solution, such as the equation x + 10 = 25. For students in fifth grade, the Common Core standard for algebraic thinking expects them to…
Generalized Klein-Kramers equations.
Fa, Kwok Sau
2012-12-21
A generalized Klein-Kramers equation for a particle interacting with an external field is proposed. The equation generalizes the fractional Klein-Kramers equation introduced by Barkai and Silbey [J. Phys. Chem. B 104, 3866 (2000)]. Besides, the generalized Klein-Kramers equation can also recover the integro-differential Klein-Kramers equation for continuous-time random walk; this means that it can describe the subdiffusive and superdiffusive regimes in the long-time limit. Moreover, analytic solutions for first two moments both in velocity and displacement (for force-free case) are obtained, and their dynamic behaviors are investigated.
ERIC Educational Resources Information Center
Powers, Sonya Jean
2010-01-01
When test forms are administered to examinee groups that differ in proficiency, equating procedures are used to disentangle group differences from form differences. This dissertation investigates the extent to which equating results are population invariant, the impact of group differences on equating results, the impact of group differences on…
On nonautonomous Dirac equation
Hovhannisyan, Gro; Liu Wen
2009-12-15
We construct the fundamental solution of time dependent linear ordinary Dirac system in terms of unknown phase functions. This construction gives approximate representation of solutions which is useful for the study of asymptotic behavior. Introducing analog of Rayleigh quotient for differential equations we generalize Hartman-Wintner asymptotic integration theorems with the error estimates for applications to the Dirac system. We also introduce the adiabatic invariants for the Dirac system, which are similar to the adiabatic invariant of Lorentz's pendulum. Using a small parameter method it is shown that the change in the adiabatic invariants approaches zero with the power speed as a small parameter approaches zero. As another application we calculate the transition probabilities for the Dirac system. We show that for the special choice of electromagnetic field, the only transition of an electron to the positron with the opposite spin orientation is possible.
NASA Astrophysics Data System (ADS)
Gomez, Humberto
2016-06-01
The CHY representation of scattering amplitudes is based on integrals over the moduli space of a punctured sphere. We replace the punctured sphere by a double-cover version. The resulting scattering equations depend on a parameter Λ controlling the opening of a branch cut. The new representation of scattering amplitudes possesses an enhanced redundancy which can be used to fix, modulo branches, the location of four punctures while promoting Λ to a variable. Via residue theorems we show how CHY formulas break up into sums of products of smaller (off-shell) ones times a propagator. This leads to a powerful way of evaluating CHY integrals of generic rational functions, which we call the Λ algorithm.
NASA Astrophysics Data System (ADS)
Cardona, Carlos; Gomez, Humberto
2016-06-01
Recently the CHY approach has been extended to one loop level using elliptic functions and modular forms over a Jacobian variety. Due to the difficulty in manipulating these kind of functions, we propose an alternative prescription that is totally algebraic. This new proposal is based on an elliptic algebraic curve embedded in a mathbb{C}{P}^2 space. We show that for the simplest integrand, namely the n - gon, our proposal indeed reproduces the expected result. By using the recently formulated Λ-algorithm, we found a novel recurrence relation expansion in terms of tree level off-shell amplitudes. Our results connect nicely with recent results on the one-loop formulation of the scattering equations. In addition, this new proposal can be easily stretched out to hyperelliptic curves in order to compute higher genus.
NASA Astrophysics Data System (ADS)
Frimmer, Martin; Novotny, Lukas
2014-10-01
Coherent control of a quantum mechanical two-level system is at the heart of magnetic resonance imaging, quantum information processing, and quantum optics. Among the most prominent phenomena in quantum coherent control are Rabi oscillations, Ramsey fringes, and Hahn echoes. We demonstrate that these phenomena can be derived classically by use of a simple coupled-harmonic-oscillator model. The classical problem can be cast in a form that is formally equivalent to the quantum mechanical Bloch equations with the exception that the longitudinal and the transverse relaxation times (T1 and T2) are equal. The classical analysis is intuitive and well suited for familiarizing students with the basic concepts of quantum coherent control, while at the same time highlighting the fundamental differences between classical and quantum theories.
Structural Equation Model Trees
Brandmaier, Andreas M.; von Oertzen, Timo; McArdle, John J.; Lindenberger, Ulman
2015-01-01
In the behavioral and social sciences, structural equation models (SEMs) have become widely accepted as a modeling tool for the relation between latent and observed variables. SEMs can be seen as a unification of several multivariate analysis techniques. SEM Trees combine the strengths of SEMs and the decision tree paradigm by building tree structures that separate a data set recursively into subsets with significantly different parameter estimates in a SEM. SEM Trees provide means for finding covariates and covariate interactions that predict differences in structural parameters in observed as well as in latent space and facilitate theory-guided exploration of empirical data. We describe the methodology, discuss theoretical and practical implications, and demonstrate applications to a factor model and a linear growth curve model. PMID:22984789
Solitary Wave Solutions of KP equation, Cylindrical KP Equation and Spherical KP Equation
NASA Astrophysics Data System (ADS)
Li, Xiang-Zheng; Zhang, Jin-Liang; Wang, Ming-Liang
2017-02-01
Three (2+1)-dimensional equations–KP equation, cylindrical KP equation and spherical KP equation, have been reduced to the same KdV equation by different transformation of variables respectively. Since the single solitary wave solution and 2-solitary wave solution of the KdV equation have been known already, substituting the solutions of the KdV equation into the corresponding transformation of variables respectively, the single and 2-solitary wave solutions of the three (2+1)-dimensional equations can be obtained successfully. Supported by the National Natural Science Foundation of China under Grant No. 11301153 and the Doctoral Foundation of Henan University of Science and Technology under Grant No. 09001562, and the Science and Technology Innovation Platform of Henan University of Science and Technology under Grant No. 2015XPT001
Mode decomposition evolution equations
Wang, Yang; Wei, Guo-Wei; Yang, Siyang
2011-01-01
Partial differential equation (PDE) based methods have become some of the most powerful tools for exploring the fundamental problems in signal processing, image processing, computer vision, machine vision and artificial intelligence in the past two decades. The advantages of PDE based approaches are that they can be made fully automatic, robust for the analysis of images, videos and high dimensional data. A fundamental question is whether one can use PDEs to perform all the basic tasks in the image processing. If one can devise PDEs to perform full-scale mode decomposition for signals and images, the modes thus generated would be very useful for secondary processing to meet the needs in various types of signal and image processing. Despite of great progress in PDE based image analysis in the past two decades, the basic roles of PDEs in image/signal analysis are only limited to PDE based low-pass filters, and their applications to noise removal, edge detection, segmentation, etc. At present, it is not clear how to construct PDE based methods for full-scale mode decomposition. The above-mentioned limitation of most current PDE based image/signal processing methods is addressed in the proposed work, in which we introduce a family of mode decomposition evolution equations (MoDEEs) for a vast variety of applications. The MoDEEs are constructed as an extension of a PDE based high-pass filter (Europhys. Lett., 59(6): 814, 2002) by using arbitrarily high order PDE based low-pass filters introduced by Wei (IEEE Signal Process. Lett., 6(7): 165, 1999). The use of arbitrarily high order PDEs is essential to the frequency localization in the mode decomposition. Similar to the wavelet transform, the present MoDEEs have a controllable time-frequency localization and allow a perfect reconstruction of the original function. Therefore, the MoDEE operation is also called a PDE transform. However, modes generated from the present approach are in the spatial or time domain and can be
Mode decomposition evolution equations.
Wang, Yang; Wei, Guo-Wei; Yang, Siyang
2012-03-01
Partial differential equation (PDE) based methods have become some of the most powerful tools for exploring the fundamental problems in signal processing, image processing, computer vision, machine vision and artificial intelligence in the past two decades. The advantages of PDE based approaches are that they can be made fully automatic, robust for the analysis of images, videos and high dimensional data. A fundamental question is whether one can use PDEs to perform all the basic tasks in the image processing. If one can devise PDEs to perform full-scale mode decomposition for signals and images, the modes thus generated would be very useful for secondary processing to meet the needs in various types of signal and image processing. Despite of great progress in PDE based image analysis in the past two decades, the basic roles of PDEs in image/signal analysis are only limited to PDE based low-pass filters, and their applications to noise removal, edge detection, segmentation, etc. At present, it is not clear how to construct PDE based methods for full-scale mode decomposition. The above-mentioned limitation of most current PDE based image/signal processing methods is addressed in the proposed work, in which we introduce a family of mode decomposition evolution equations (MoDEEs) for a vast variety of applications. The MoDEEs are constructed as an extension of a PDE based high-pass filter (Europhys. Lett., 59(6): 814, 2002) by using arbitrarily high order PDE based low-pass filters introduced by Wei (IEEE Signal Process. Lett., 6(7): 165, 1999). The use of arbitrarily high order PDEs is essential to the frequency localization in the mode decomposition. Similar to the wavelet transform, the present MoDEEs have a controllable time-frequency localization and allow a perfect reconstruction of the original function. Therefore, the MoDEE operation is also called a PDE transform. However, modes generated from the present approach are in the spatial or time domain and can be
Coagulation equations with gelation
Hendriks, E.M.; Ernst, M.H.; Ziff, R.M.
1983-06-01
Smoluchowski's equation for rapid coagulation is used to describe the kinetics of gelation, in which the coagulation kernel K/sub i/j models the bonding mechanism. For different classes of kernels we derive criteria for the occurrences of gelation, and obtain critical exponents in the pre- and postgelation stage in terms of the model parameters; we calculate bounds on the time of gelation t/sub c/, and give an exact postgelation solution for the model K/sub i/j = (ij)/sup ..omega../ (..omega..>1/2) and K/sub i/j = ..cap alpha../sup i/+j (..cap alpha..>1). For the model K/sub i/j = i/sup ..omega../+j/sup ..omega../ (..omega..<1, without gelation) initial solutions are given. It is argued that the kernel K/sub i/japprox. (ij)/sup ..omega../ with ..omega..approx. =1-1/d (d is dimensionality) effectively models the sol-gel transformation is polymerizing systems and approximately accounts for the effects of cross-linking and steric hindrance neglected in the classical theory of Flory and Stockmayer (..omega.. = 1). For all ..omega.. the exponents, tau = ..omega..+3/2 and sigma = ..omega..-1/2, ..gamma.. = (3/2-..omega..)/(..omega..-1/2) and ..beta.. = 1, characterize the size distribution, at the slightly below the gel point, under the assumption that scaling is valid.
NASA Astrophysics Data System (ADS)
Sivron, Ran
2006-12-01
With the introduction of "Ranking Tests" some quantitative ideas were added to a large body of successful techniques for teaching conceptual astronomy. We incorporated those methods into our classes, and added a new ingredient: On a biweekly basis we included a quantitative excercise: Students working in groups of 2-3 draw geometrical figures, say: a circle, and use some trivial geometry equations, such as circumference = 2 x pi x r, in solving astronomy problems on 3'x4' white boards. A few examples included: Finding the distance to the moon with the Aristarchus method, finding the Solar Constant with the inverse square law, etc. Our methodolgy was similar to problem solving techniques in introductory physics. We were therefore worried that the students may be intimidated. To our surprize, not only did most students succeed in solving the problems, but they were not intimidated at all (that is: after the first class...) As a matter of fact, their test results improved, and the students interviewed expressed great enthusiasm for the new method. Warning: Our classes were relatively small <40 studets). For larger classes TA help is needed.
Menikoff, Ralph
2015-12-15
The JWL equation of state (EOS) is frequently used for the products (and sometimes reactants) of a high explosive (HE). Here we review and systematically derive important properties. The JWL EOS is of the Mie-Grueneisen form with a constant Grueneisen coefficient and a constants specific heat. It is thermodynamically consistent to specify the temperature at a reference state. However, increasing the reference state temperature restricts the EOS domain in the (V, e)-plane of phase space. The restrictions are due to the conditions that P ≥ 0, T ≥ 0, and the isothermal bulk modulus is positive. Typically, this limits the low temperature regime in expansion. The domain restrictions can result in the P-T equilibrium EOS of a partly burned HE failing to have a solution in some cases. For application to HE, the heat of detonation is discussed. Example JWL parameters for an HE, both products and reactions, are used to illustrate the restrictions on the domain of the EOS.
A note on "Kepler's equation".
NASA Astrophysics Data System (ADS)
Dutka, J.
1997-07-01
This note briefly points out the formal similarity between Kepler's equation and equations developed in Hindu and Islamic astronomy for describing the lunar parallax. Specifically, an iterative method for calculating the lunar parallax has been developed by the astronomer Habash al-Hasib al-Marwazi (about 850 A.D., Turkestan), which is surprisingly similar to the iterative method for solving Kepler's equation invented by Leonhard Euler (1707 - 1783).
Electronic representation of wave equation
NASA Astrophysics Data System (ADS)
Veigend, Petr; Kunovský, Jiří; Kocina, Filip; Nečasová, Gabriela; Šátek, Václav; Valenta, Václav
2016-06-01
The Taylor series method for solving differential equations represents a non-traditional way of a numerical solution. Even though this method is not much preferred in the literature, experimental calculations done at the Department of Intelligent Systems of the Faculty of Information Technology of TU Brno have verified that the accuracy and stability of the Taylor series method exceeds the currently used algorithms for numerically solving differential equations. This paper deals with solution of Telegraph equation using modelling of a series small pieces of the wire. Corresponding differential equations are solved by the Modern Taylor Series Method.
Sedeonic equations of ideal fluid
NASA Astrophysics Data System (ADS)
Mironov, Victor L.; Mironov, Sergey V.
2017-08-01
In the present paper, we propose the generalized equations for an ideal fluid based on space-time algebra of sixteen-component sedeons. It is shown that the dynamics of isentropic fluid can be described by sedeonic first-order wave equation for fluid potentials. The key features of the proposed formalism are illustrated on the problem of the sound waves propagation. We consider the plane wave solution of linearized sedeonic wave equation and derive the second-order relations for the sound potential analogues to the Poynting theorem in electrodynamics. The generalization of proposed sedeonic equations for the description of viscous fluid is also discussed.
Electronic representation of wave equation
Veigend, Petr; Kunovský, Jiří Kocina, Filip; Nečasová, Gabriela; Valenta, Václav; Šátek, Václav
2016-06-08
The Taylor series method for solving differential equations represents a non-traditional way of a numerical solution. Even though this method is not much preferred in the literature, experimental calculations done at the Department of Intelligent Systems of the Faculty of Information Technology of TU Brno have verified that the accuracy and stability of the Taylor series method exceeds the currently used algorithms for numerically solving differential equations. This paper deals with solution of Telegraph equation using modelling of a series small pieces of the wire. Corresponding differential equations are solved by the Modern Taylor Series Method.
A Circuit Equation as a Limit of Eddy Current Equations
NASA Astrophysics Data System (ADS)
Amirat, Youcef; Touzani, Rachid
2017-06-01
We consider a three-dimensional time-harmonic eddy current problem formulated in terms of the magnetic field. We prove that in the case of one thin toroidal conductor, eddy current equations have as a limit Kirchhoff's algebraic equation for circuits. This approximation is valid in the case of small resistivity and voltage.
A Circuit Equation as a Limit of Eddy Current Equations
NASA Astrophysics Data System (ADS)
Amirat, Youcef; Touzani, Rachid
2017-10-01
We consider a three-dimensional time-harmonic eddy current problem formulated in terms of the magnetic field. We prove that in the case of one thin toroidal conductor, eddy current equations have as a limit Kirchhoff's algebraic equation for circuits. This approximation is valid in the case of small resistivity and voltage.
Darling, P.
1995-10-01
In the mid-1970s PT Rio Tinto Indonesia, a wholly owned subsidiary of CRA of Australia, entered into an agreement with BP of the United Kingdom to explore jointly for coal in Indonesia on a 50:50 basis. In 1978, the government of Indonesia invited tenders from foreign companies for the exploration and development of coal resources in eastern and southern Kalimantan (Borneo). The CRA-BP joint venture was successful in bidding for an area of 7,900 km{sup 2} in two blocks extending 300 km along the coast of eastern Kalimantan. In April 1982, PT Kaltim Prima Coal (KPC) entered into an agreement with the Indonesian State Coal Company whereby it could explore, produce, and market coal from the agreed blocks for a period of 30 years. From 1982 to 1986, detailed exploration led to the delineation of several propsects of which the most promising was near the small town of Sangatta, 200 km north of Balikpapan and less than one degree north of the equator. After this exploration period KPC relinquished all but 1,962 km{sup 2} of the original agreement area. In its simplest form, the mining operation can be described as: a series of open pits, coal preparation facilities, 13.7 km of overland conveyor to the coast, and a marine terminal capable of handling bulk carriers of up to 200K dwt. The remote location necessities a fully supportive infrastructure, including a power station, housing, schools, hospitals, water supply, and recreational facilities. In 1994 the mine produced 10M mt coal of which 70% was Prima coal, one of the highest quality internationally traded thermal coals.
Graphical Solution of Polynomial Equations
ERIC Educational Resources Information Center
Grishin, Anatole
2009-01-01
Graphing utilities, such as the ubiquitous graphing calculator, are often used in finding the approximate real roots of polynomial equations. In this paper the author offers a simple graphing technique that allows one to find all solutions of a polynomial equation (1) of arbitrary degree; (2) with real or complex coefficients; and (3) possessing…
Homotopy Solutions of Kepler's Equations
NASA Technical Reports Server (NTRS)
Fitz-Coy, Norman; Jang, Jiann-Woei
1996-01-01
Kepler's Equation is solved using an integrative algorithm developed using homotropy theory. The solution approach is applicable to both elliptic and hyperbolic forms of Kepler's Equation. The results from the proposed algorithm compare quite favorably with those from existing iterative schemes.
Students' Understanding of Quadratic Equations
ERIC Educational Resources Information Center
López, Jonathan; Robles, Izraim; Martínez-Planell, Rafael
2016-01-01
Action-Process-Object-Schema theory (APOS) was applied to study student understanding of quadratic equations in one variable. This required proposing a detailed conjecture (called a genetic decomposition) of mental constructions students may do to understand quadratic equations. The genetic decomposition which was proposed can contribute to help…
How Students Understand Physics Equations.
ERIC Educational Resources Information Center
Sherin, Bruce L.
2001-01-01
Analyzed a corpus of videotapes in which university students solved physics problems to determine how students learn to understand a physics equation. Found that students learn to understand physics equations in terms of a vocabulary of elements called symbolic forms, each associating a simple conceptual schema with a pattern of symbols. Findings…
Uncertainty of empirical correlation equations
NASA Astrophysics Data System (ADS)
Feistel, R.; Lovell-Smith, J. W.; Saunders, P.; Seitz, S.
2016-08-01
The International Association for the Properties of Water and Steam (IAPWS) has published a set of empirical reference equations of state, forming the basis of the 2010 Thermodynamic Equation of Seawater (TEOS-10), from which all thermodynamic properties of seawater, ice, and humid air can be derived in a thermodynamically consistent manner. For each of the equations of state, the parameters have been found by simultaneously fitting equations for a range of different derived quantities using large sets of measurements of these quantities. In some cases, uncertainties in these fitted equations have been assigned based on the uncertainties of the measurement results. However, because uncertainties in the parameter values have not been determined, it is not possible to estimate the uncertainty in many of the useful quantities that can be calculated using the parameters. In this paper we demonstrate how the method of generalised least squares (GLS), in which the covariance of the input data is propagated into the values calculated by the fitted equation, and in particular into the covariance matrix of the fitted parameters, can be applied to one of the TEOS-10 equations of state, namely IAPWS-95 for fluid pure water. Using the calculated parameter covariance matrix, we provide some preliminary estimates of the uncertainties in derived quantities, namely the second and third virial coefficients for water. We recommend further investigation of the GLS method for use as a standard method for calculating and propagating the uncertainties of values computed from empirical equations.
Drug Levels and Difference Equations
ERIC Educational Resources Information Center
Acker, Kathleen A.
2004-01-01
American university offers a course in finite mathematics whose focus is difference equation with emphasis on real world applications. The conclusion states that students learned to look for growth and decay patterns in raw data, to recognize both arithmetic and geometric growth, and to model both scenarios with graphs and difference equations.
The report describes a program for computing equation of state parameters for a material which undergoes a phase transition, either rate-dependent or...obtaining explicit temperature dependence if measurements are made at three temperatures. It is applied to data from calcite. Finally a theoretical equation of state is described for solid iron. (Author)
Complete solution of Boolean equations
NASA Technical Reports Server (NTRS)
Tapia, M. A.; Tucker, J. H.
1980-01-01
A method is presented for generating a single formula involving arbitary Boolean parameters, which includes in it each and every possible solution of a system of Boolean equations. An alternate condition equivalent to a known necessary and sufficient condition for solving a system of Boolean equations is given.
Students' Understanding of Quadratic Equations
ERIC Educational Resources Information Center
López, Jonathan; Robles, Izraim; Martínez-Planell, Rafael
2016-01-01
Action-Process-Object-Schema theory (APOS) was applied to study student understanding of quadratic equations in one variable. This required proposing a detailed conjecture (called a genetic decomposition) of mental constructions students may do to understand quadratic equations. The genetic decomposition which was proposed can contribute to help…
Generalized Multilevel Structural Equation Modeling
ERIC Educational Resources Information Center
Rabe-Hesketh, Sophia; Skrondal, Anders; Pickles, Andrew
2004-01-01
A unifying framework for generalized multilevel structural equation modeling is introduced. The models in the framework, called generalized linear latent and mixed models (GLLAMM), combine features of generalized linear mixed models (GLMM) and structural equation models (SEM) and consist of a response model and a structural model for the latent…
The Bessel Equation and Dissipation
NASA Astrophysics Data System (ADS)
Alfinito, Eleonora; Vitiello, Giuseppe
The Bessel equation can be cast, by means of suitable transformations, into a system of two damped/amplified parametric oscillator equations. The role of group contraction and the breakdown of loop-antiloop symmetry is discussed. The relation between the Virasoro algebra and the Euclidean algebras e(2) and e(3) is also presented.
The Equations of Oceanic Motions
NASA Astrophysics Data System (ADS)
Müller, Peter
2006-10-01
Modeling and prediction of oceanographic phenomena and climate is based on the integration of dynamic equations. The Equations of Oceanic Motions derives and systematically classifies the most common dynamic equations used in physical oceanography, from large scale thermohaline circulations to those governing small scale motions and turbulence. After establishing the basic dynamical equations that describe all oceanic motions, M|ller then derives approximate equations, emphasizing the assumptions made and physical processes eliminated. He distinguishes between geometric, thermodynamic and dynamic approximations and between the acoustic, gravity, vortical and temperature-salinity modes of motion. Basic concepts and formulae of equilibrium thermodynamics, vector and tensor calculus, curvilinear coordinate systems, and the kinematics of fluid motion and wave propagation are covered in appendices. Providing the basic theoretical background for graduate students and researchers of physical oceanography and climate science, this book will serve as both a comprehensive text and an essential reference.
Upper bounds for parabolic equations and the Landau equation
NASA Astrophysics Data System (ADS)
Silvestre, Luis
2017-02-01
We consider a parabolic equation in nondivergence form, defined in the full space [ 0 , ∞) ×Rd, with a power nonlinearity as the right-hand side. We obtain an upper bound for the solution in terms of a weighted control in Lp. This upper bound is applied to the homogeneous Landau equation with moderately soft potentials. We obtain an estimate in L∞ (Rd) for the solution of the Landau equation, for positive time, which depends only on the mass, energy and entropy of the initial data.
ERIC Educational Resources Information Center
Ozdemir, Burhanettin
2017-01-01
The purpose of this study is to equate Trends in International Mathematics and Science Study (TIMSS) mathematics subtest scores obtained from TIMSS 2011 to scores obtained from TIMSS 2007 form with different nonlinear observed score equating methods under Non-Equivalent Anchor Test (NEAT) design where common items are used to link two or more test…
Higher derivative gravity: Field equation as the equation of state
NASA Astrophysics Data System (ADS)
Dey, Ramit; Liberati, Stefano; Mohd, Arif
2016-08-01
One of the striking features of general relativity is that the Einstein equation is implied by the Clausius relation imposed on a small patch of locally constructed causal horizon. The extension of this thermodynamic derivation of the field equation to more general theories of gravity has been attempted many times in the last two decades. In particular, equations of motion for minimally coupled higher-curvature theories of gravity, but without the derivatives of curvature, have previously been derived using a thermodynamic reasoning. In that derivation the horizon slices were endowed with an entropy density whose form resembles that of the Noether charge for diffeomorphisms, and was dubbed the Noetheresque entropy. In this paper, we propose a new entropy density, closely related to the Noetheresque form, such that the field equation of any diffeomorphism-invariant metric theory of gravity can be derived by imposing the Clausius relation on a small patch of local causal horizon.
On the Shallow Water Equations
NASA Astrophysics Data System (ADS)
Abdelrahman, Mahmoud A. E.
2017-08-01
We studied the shallow water equations of nonlinear conservation laws. First we studied the parametrisation of nonlinear elementary waves and hence we present the solution to the Riemann problem. We also prove the uniqueness of the Riemann solution. The Riemann invariants are formulated. Moreover we give an interesting application of the Riemann invariants. We present the shallow water system in a diagonal form, which admits the existence of a global smooth solution for these equations. The other application is to introduce new conservation laws for the shallow water equations.
Langevin equations from time series.
Racca, E; Porporato, A
2005-02-01
We discuss the link between the approach to obtain the drift and diffusion of one-dimensional Langevin equations from time series, and Pope and Ching's relationship for stationary signals. The two approaches are based on different interpretations of conditional averages of the time derivatives of the time series at given levels. The analysis provides a useful indication for the correct application of Pope and Ching's relationship to obtain stochastic differential equations from time series and shows its validity, in a generalized sense, for nondifferentiable processes originating from Langevin equations.
NASA Technical Reports Server (NTRS)
Shebalin, John V.
1987-01-01
The Boussinesq approximation is extended so as to explicitly account for the transfer of fluid energy through viscous action into thermal energy. Ideal and dissipative integral invariants are discussed, in addition to the general equations for thermal-fluid motion.
Parametric Equations, Maple, and Tubeplots.
ERIC Educational Resources Information Center
Feicht, Louis
1997-01-01
Presents an activity that establishes a graphical foundation for parametric equations by using a graphing output form called tubeplots from the computer program Maple. Provides a comprehensive review and exploration of many previously learned topics. (ASK)
On systems of Boolean equations
NASA Astrophysics Data System (ADS)
Leont'ev, V. K.; Tonoyan, G. P.
2013-05-01
Systems of Boolean equations are considered. The order of maximal consistent subsystems is estimated in the general and "typical" (in a probability sense) cases. Applications for several well-known discrete problems are given.
Accuracy of perturbative master equations.
Fleming, C H; Cummings, N I
2011-03-01
We consider open quantum systems with dynamics described by master equations that have perturbative expansions in the system-environment interaction. We show that, contrary to intuition, full-time solutions of order-2n accuracy require an order-(2n+2) master equation. We give two examples of such inaccuracies in the solutions to an order-2n master equation: order-2n inaccuracies in the steady state of the system and order-2n positivity violations. We show how these arise in a specific example for which exact solutions are available. This result has a wide-ranging impact on the validity of coupling (or friction) sensitive results derived from second-order convolutionless, Nakajima-Zwanzig, Redfield, and Born-Markov master equations.
Comment on "Quantum Raychaudhuri equation"
NASA Astrophysics Data System (ADS)
Lashin, E. I.; Dou, Djamel
2017-03-01
We address the validity of the formalism and results presented in S. Das, Phys. Rev. D 89, 084068 (2014), 10.1103/PhysRevD.89.084068 with regard to the quantum Raychaudhuri equation. The author obtained the so-called quantum Raychaudhuri equation by replacing classical geodesics with quantal trajectories arising from Bhommian mechanics. The resulting modified equation was used to draw some conclusions about the inevitability of focusing and the formation of conjugate points and therefore singularity. We show that the whole procedure is full of problematic points, on both physical relevancy and mathematical correctness. In particular, we illustrate the problems associated with the technical derivation of the so-called quantum Raychaudhuri equation, as well as its invalid physical implications.
Fractional Differential Equations and Multifractality
NASA Astrophysics Data System (ADS)
Larcheveque, M.; Schertzer, D. J.; Schertzer, D. J.; Duan, J.; Lovejoy, S.
2001-12-01
There has been a mushrooming interest in the linear Fokker-Planck Equation (FPPE) which corresponds to the generating equation of Lévy's anomalous diffusion. We already pointed out some theoretical and empirical limitations of the linear FPPE for various geophysical problems: the medium is in fact considered as homogeneous and the exponent of the power law of the pdf tails should be smaller than 2. We showed that a nonlinear extension based on a nonlinear Langevin equation forced by a Lévy stable motion overcomes these limitations. We show that in order to generate multifractal diffusion, and more generally multifractal fields, we need to furthermore consider fractional time derivatives in the Langevin equation and in FPPE. We compare our approach with the Continuous-Time Random Walk (CTWR) approach.
Taxis equations for amoeboid cells.
Erban, Radek; Othmer, Hans G
2007-06-01
The classical macroscopic chemotaxis equations have previously been derived from an individual-based description of the tactic response of cells that use a "run-and-tumble" strategy in response to environmental cues [17,18]. Here we derive macroscopic equations for the more complex type of behavioral response characteristic of crawling cells, which detect a signal, extract directional information from a scalar concentration field, and change their motile behavior accordingly. We present several models of increasing complexity for which the derivation of population-level equations is possible, and we show how experimentally measured statistics can be obtained from the transport equation formalism. We also show that amoeboid cells that do not adapt to constant signals can still aggregate in steady gradients, but not in response to periodic waves. This is in contrast to the case of cells that use a "run-and-tumble" strategy, where adaptation is essential.
Derivation of the Simon equation
NASA Astrophysics Data System (ADS)
Fedorov, P. P.
2016-09-01
The form of the empirical Simon equation describing the dependence of the phase-transition temperature on pressure is shown to be asymptotically strict when the system tends to absolute zero of temperature, and then only for crystalline phases.
Friedmann equation with quantum potential
Siong, Ch'ng Han; Radiman, Shahidan; Nikouravan, Bijan
2013-11-27
Friedmann equations are used to describe the evolution of the universe. Solving Friedmann equations for the scale factor indicates that the universe starts from an initial singularity where all the physical laws break down. However, the Friedmann equations are well describing the late-time or large scale universe. Hence now, many physicists try to find an alternative theory to avoid this initial singularity. In this paper, we generate a version of first Friedmann equation which is added with an additional term. This additional term contains the quantum potential energy which is believed to play an important role at small scale. However, it will gradually become negligible when the universe evolves to large scale.
Hidden Statistics of Schroedinger Equation
NASA Technical Reports Server (NTRS)
Zak, Michail
2011-01-01
Work was carried out in determination of the mathematical origin of randomness in quantum mechanics and creating a hidden statistics of Schr dinger equation; i.e., to expose the transitional stochastic process as a "bridge" to the quantum world. The governing equations of hidden statistics would preserve such properties of quantum physics as superposition, entanglement, and direct-product decomposability while allowing one to measure its state variables using classical methods.
Fractional generalization of Liouville equations.
Tarasov, Vasily E
2004-03-01
In this paper fractional generalization of Liouville equation is considered. We derive fractional analog of normalization condition for distribution function. Fractional generalization of the Liouville equation for dissipative and Hamiltonian systems was derived from the fractional normalization condition. This condition is considered as a normalization condition for systems in fractional phase space. The interpretation of the fractional space is discussed. Copyright 2004 American Institute of Physics.
Wave equations for pulse propagation
Shore, B.W.
1987-06-24
Theoretical discussions of the propagation of pulses of laser radiation through atomic or molecular vapor rely on a number of traditional approximations for idealizing the radiation and the molecules, and for quantifying their mutual interaction by various equations of propagation (for the radiation) and excitation (for the molecules). In treating short-pulse phenomena it is essential to consider coherent excitation phenomena of the sort that is manifest in Rabi oscillations of atomic or molecular populations. Such processes are not adequately treated by rate equations for excitation nor by rate equations for radiation. As part of a more comprehensive treatment of the coupled equations that describe propagation of short pulses, this memo presents background discussion of the equations that describe the field. This memo discusses the origin, in Maxwell's equations, of the wave equation used in the description of pulse propagation. It notes the separation into lamellar and solenoidal (or longitudinal and transverse) and positive and negative frequency parts. It mentions the possibility of separating the polarization field into linear and nonlinear parts, in order to define a susceptibility or index of refraction and, from these, a phase and group velocity. The memo discusses various ways of characterizing the polarization characteristics of plane waves, that is, of parameterizing a transverse unit vector, such as the Jones vector, the Stokes vector, and the Poincare sphere. It discusses the connection between macroscopically defined quantities, such as the intensity or, more generally, the Stokes parameters, and microscopic field amplitudes. The material presented here is a portion of a more extensive treatment of propagation to be presented separately. The equations presented here have been described in various books and articles. They are collected here as a summary and review of theory needed when treating pulse propagation.
Program solves line flow equation
McCaslin, K.P.
1981-01-19
A program written for the TI-59 programmable calculator solves the Panhandle Eastern A equation - an industry-accepted equation for calculating pressure losses in high-pressure gas-transmission pipelines. The input variables include the specific gravity of the gas, the flowing temperature, the pipeline efficiency, the base temperature and pressure, the inlet pressure, the pipeline's length and inside diameter, and the flow rate (SCF/day); the program solves for the discharge pressure.
An Exact Mapping from Navier-Stokes Equation to Schr"odinger Equation via Riccati Equation
NASA Astrophysics Data System (ADS)
Christianto, Vic; Smarandache, Florentin
2010-03-01
In the present article we argue that it is possible to write down Schr"odinger representation of Navier-Stokes equation via Riccati equation. The proposed approach, while differs appreciably from other method such as what is proposed by R. M. Kiehn, has an advantage, i.e. it enables us extend further to quaternionic and biquaternionic version of Navier-Stokes equation, for instance via Kravchenko's and Gibbon's route. Further observation is of course recommended in order to refute or verify this proposition.
The soil moisture velocity equation
NASA Astrophysics Data System (ADS)
Ogden, Fred L.; Allen, Myron B.; Lai, Wencong; Zhu, Jianting; Seo, Mookwon; Douglas, Craig C.; Talbot, Cary A.
2017-06-01
Numerical solution of the one-dimensional Richards' equation is the recommended method for coupling groundwater to the atmosphere through the vadose zone in hyperresolution Earth system models, but requires fine spatial discretization, is computationally expensive, and may not converge due to mathematical degeneracy or when sharp wetting fronts occur. We transformed the one-dimensional Richards' equation into a new equation that describes the velocity of moisture content values in an unsaturated soil under the actions of capillarity and gravity. We call this new equation the Soil Moisture Velocity Equation (SMVE). The SMVE consists of two terms: an advection-like term that accounts for gravity and the integrated capillary drive of the wetting front, and a diffusion-like term that describes the flux due to the shape of the wetting front capillarity profile divided by the vertical gradient of the capillary pressure head. The SMVE advection-like term can be converted to a relatively easy to solve ordinary differential equation (ODE) using the method of lines and solved using a finite moisture-content discretization. Comparing against analytical solutions of Richards' equation shows that the SMVE advection-like term is >99% accurate for calculating infiltration fluxes neglecting the diffusion-like term. The ODE solution of the SMVE advection-like term is accurate, computationally efficient and reliable for calculating one-dimensional vadose zone fluxes in Earth system and large-scale coupled models of land-atmosphere interaction. It is also well suited for use in inverse problems such as when repeat remote sensing observations are used to infer soil hydraulic properties or soil moisture.