Allowance For Effects Research Articles

Helicity in dynamic atmospheric processes

An overview on the helicity of the velocity field and the role played by this concept in modern research in the field of geophysical fluid dynamics and dynamic meteorology is given. Different (both previously known in the literature and first presented) formulations of the equation of helicity balance in atmospheric motions (including those with allowance for effects of air compressibility and Earth’s rotation) are brought together. Equations and relationships are given which are valid in different approximations accepted in dynamic meteorology: Boussinesq approximation, quasi-static approximation, and quasi-geostrophic approximation. Emphasis is placed on the analysis of helicity budget in large-scale quasi-geostrophic systems of motion; a formula for the helicity flux across the upper boundary of the nonlinear Ekman boundary layer is given, and this flux is shown to be exactly compensated for by the helicity destruction inside the Ekman boundary layer.

Time variations of geopotential coefficients in the structure of the oscillatory process of the Earth’s pole

A numerical-analytical model of the oscillatory motion of the Earth’s pole is proposed with allowance for effects of time variations in geopotential coefficients. The model is a natural refinement of the earlier developed main model of pole oscillations (of Chandler and annual components) by use of celestial mechanics methods and observation data of the gravitational field of the Earth. Based on amplitude-frequency analysis and numerical simulation of the pole motion, the model allows one to offer a qualitative explanation of observed irregular phenomena in the oscillatory process and improve the forecasting accuracy for the trajectory of the pole motion. The results of numerical simulation of oscillations of the pole coordinates are presented in comparison with observation and measurement data of the International Earth Rotation Service (IERS).

Kinetic equation in the self-consistent field approximation for the number density of filaments forming in the propagation of femtosecond laser radiation

The general form of the kinetic equation for the filament number density with allowance for effects of their creation and decay is formulated—a nonlinear diffusion equation. The equation includes phenomenological parameters obtained by direct numerical simulation of the propagation of a high-power femtosecond laser pulse based on the stationary nonlinear Schrobinger equation for a number of limiting special cases.

Developing Regimes for the Asymmetric Rolling of Low-Alloy Steel Plates to Minimize Bending of the Ends of the Plate

It is established that when plates are rolled in work rolls operating at different speeds, the direction in which the front end of the plate bends is determined by the plate’s thickness and temperature, the shape factor of the deformation zone, and the difference in roll speeds. It was determined that the finish rolling of plates in the 20‐40-mm thickness range must be performed with allowance for the combined effect of three asymmetry factors ‐ geometric, thermal, and kinematic. New asymmetric deformation regimes were developed for rolling with different work-rolls speeds with allowance for the effect of the shape factor of the deformation zone on the direction of bending of plates’ front end. The new regimes have reduced mill downtime and the volume of products that are rejected.

Relationship Between Sleep Problems and Quality of Life in Children With ADHD

Objective: The purpose of this study is to assess the sleep behaviors, sleep problems and frequency, and relationship with psychiatric comorbidities in ADHD Combined type and to evaluate the effect of sleep problems on quality of life. Method: Forty-six boys, aged 7 to 13 years, with ADHD-combined type and 31 healthy boys were included. ADHD children were never treated for sleep or psychiatric disorders. Intelligence quotient (IQ) test scores were minimum 80, body mass index were normal and did not have medical disorders. Parents completed Children’s Sleep Habits Questionnaire, Conners’ Parent Rating Scale and The Pediatric Quality of Life Inventory (PedsQL) and participants were asked about sleep behaviors and were administered PedsQL and Schedule for Affective Disorders and Schizophrenia. Results: The frequency of sleep problems in ADHD is 84.8%, higher than the control group (p = .002). Evaluating PedsQL scores, the quality of life is worse in physical, psychosocial health, and total life quality (p < .05). ADHD group with sleep problems have more night wakings than control group with sleep problems (p = .02). The comorbidity do not increase sleep problems. The frequency of parasomnias is increased in group with learning disorders (p = .05). Conclusion: The results of this study, which controls for a number of possible confounders found in previous examinations of ADHD and sleep, support the results of a number of other studies that have found an increased overall prevalence of parent-reported sleep disturbances in children with ADHD compared with healthy control participants. As the ADHD group have more night wakings than the control group through the night, it is thought that night wakings that cause a partitioned sleep may be important signs seen in ADHD. That could be suggested by two hypotheses. First one is that, daytime sleepiness is more common in ADHD and those children present excessive hyperactivity during the day to stay awake and the second one is the improvement of ADHD signs when the drugs for sleepiness are used. Usage of standardized and valid diagnostic criteria, exclusion of adolescence, gender, socioeconomic level, primary sleep problems, medical disorders and low IQ level, making allowances for effect of comorbidities and having compared with the control group are the important methodological features of this study. The most important limitation of this study is small sample size that makes the findings less generalizable to other groups of children with ADHD, and another one is not having used objective measurements together with subjective measurements. In conclusion, these results underscore the importance of screening all children who have a symptom constellation suggestive of ADHD for sleep problems that may either play a causative role or exacerbate the clinical appearance of ADHD in a given child. Correct evaluation and treatment of sleep problems increase the life quality of family and child and also decrease the severity of ADHD symptoms.

Three-dimensional numerical simulation of the operation of a rotating-detonation chamber with separate supply of fuel and oxidizer

A three-dimensional numerical simulation of the operation of an annular rotating-detonation chamber (RDC) with separate supply of combustible mixture components, hydrogen and air, is performed, and the calculation results are compared to available experimental data. The model is based on a system of time-dependent Reynolds-averaged Navier-Stokes equations complemented with a turbulence model and continuity and energy equations for a multicomponent reacting gas mixture. The system is solved using a coupled algorithm based on the finite volume method and particle method. Calculations are for the first time performed with allowance for effects of finite rates of turbulent and molecular mixing of the combustible mixture components with each other and with reaction and detonation products. The calculation results compare favorably with the experimental data obtained at the Lavrentyev Institute of Hydrodynamics of the Siberian Branch of the Russian Academy of Sciences.

Hydrodynamic interaction of a nonvolatile droplet with a planar surface of evaporating liquid

Hydrodynamic interaction between a nonvolatile droplet and an infinite planar surface of an evaporating or condensing liquid is studied theoretically with allowance for effects that are linear with respect to the Knudsen number. The motion of the droplet in the direction normal to the planar liquid surface is considered at low Reynolds numbers and gradients of a gaseous medium temperature and the concentration of the substance evaporating or condensing on the planar liquid surface given at an infinitely large distance from the droplet. The presence of a temperature gradient in the liquid is taken into account in the analysis. The problem is solved in a bispherical coordinate system. The velocity of the steady motion of a castor oil droplet is numerically estimated near the planar surface of evaporating water.

Allowance for effects of thermodynamic nonideality in sedimentation equilibrium distributions reflecting protein dimerization

This reexamination of a high-speed sedimentation equilibrium distribution for α-chymotrypsin under slightly acidic conditions (pH 4.1, IM 0.05) has provided experimental support for the adequacy of nearest-neighbor considerations in the allowance for effects of thermodynamic nonideality in the characterization of protein self-association over a moderate concentration range (up to 8mg/mL). A widely held but previously untested notion about allowance for thermodynamic nonideality effects is thereby verified experimentally. However, it has also been shown that a greater obstacle to better characterization of protein self-association is likely to be the lack of a reliable estimate of monomer net charge, a parameter that has a far more profound effect on the magnitude of the measured equilibrium constant than any deficiency in current procedures for incorporating the effects of thermodynamic nonideality into the analysis of sedimentation equilibrium distributions reflecting reversible protein self-association.

Estimating the effects of Cry1F Bt‐maize pollen on non‐target Lepidoptera using a mathematical model of exposure

Summary 1. In farmland biodiversity, a potential risk to the larvae of non‐target Lepidoptera from genetically modified (GM) Bt‐maize expressing insecticidal Cry1 proteins is the ingestion of harmful amounts of pollen deposited on their host plants. A previous mathematical model of exposure quantified this risk for Cry1Ab protein. We extend this model to quantify the risk for sensitive species exposed to pollen containing Cry1F protein from maize event 1507 and to provide recommendations for management to mitigate this risk. 2. A 14‐parameter mathematical model integrating small‐ and large‐scale exposure was used to estimate the larval mortality of hypothetical species with a range of sensitivities, and under a range of simulated mitigation measures consisting of non‐Bt maize strips of different widths placed around the field edge. 3. The greatest source of variability in estimated mortality was species sensitivity. Before allowance for effects of large‐scale exposure, with moderate within‐crop host‐plant density and with no mitigation, estimated mortality locally was <10% for species of average sensitivity. For the worst‐case extreme sensitivity considered, estimated mortality locally was 99·6% with no mitigation, although this estimate was reduced to below 40% with mitigation of 24‐m‐wide strips of non‐Bt maize. For highly sensitive species, a 12‐m‐wide strip reduced estimated local mortality under 1·5%, when within‐crop host‐plant density was zero. Allowance for large‐scale exposure effects would reduce these estimates of local mortality by a highly variable amount, but typically of the order of 50‐fold. 4. Mitigation efficacy depended critically on assumed within‐crop host‐plant density; if this could be assumed negligible, then the estimated effect of mitigation would reduce local mortality below 1% even for very highly sensitive species. 5. Synthesis and applications. Mitigation measures of risks of Bt‐maize to sensitive larvae of non‐target lepidopteran species can be effective, but depend on host‐plant densities which are in turn affected by weed‐management regimes. We discuss the relevance for management of maize events where cry1F is combined (stacked) with a herbicide‐tolerance trait. This exemplifies how interactions between biota may occur when different traits are stacked irrespective of interactions between the proteins themselves and highlights the importance of accounting for crop management in the assessment of the ecological impact of GM plants.

Modelling of static aerodynamics of helicopter underslung loads

AbstractThe complex aerodynamics of rectangular underslung helicopter loads can lead to severe stability problems, but are difficult to represent in flight dynamics models. Current models for box aerodynamics are highly unsatisfactory, being entirely empirical and requiring large amounts of experimental data to generate. This paper presents a new modelling approach, which takes account of the bluff-body nature of the flow, where loads are dominated by normal pressure forces. Existing experimental data is recast in body-axes form, with α and β replaced by velocity components perpendicular and parallel to the box faces. Force and moment data for a wide range of boxes then collapse onto a set of simple generic characteristics, with features that can be related directly to the underlying flow physics. Modelling of container aerodynamics is greatly simplified, and allowance for effects of turbulence, Reynolds Number, wind tunnel interference and geometry modifications becomes possible.

Hydrodynamic interactions of evaporating droplet with droplet of nonvolatile substance

The hydrodynamic interactions of freely evaporating or growing droplet (suspended in gaseous medium) in the supersaturated vapor with the droplet of nonvolatile substance or spherical solid particle are theoretically studied with allowance for effects that are linear with respect to the Knudsen number. The process of interaction between the volatile droplet and the infinite plane surface of nonvolatile liquid or solid is considered as a limiting case. Numerical estimates of the velocities of the steady motion of evaporating droplets of water and castor oil are reported. For the droplet of water and spherical solid particle, the effect of the heat conductivity of the latter on the velocity of particle motion is considered. Analogous estimates are obtained for a water droplet that evaporates near the infinite solid surface of castor oil or solid. The effects of the droplet size and the heat conductivity of wall on the rate of the evaporation of water droplet are analyzed.

Hydrodynamic interactions of evaporating droplet with plane liquid surface

The hydrodynamic interactions between freely evaporating or growing droplet suspended in gas and the infinite plane liquid layer is theoretically studied with allowance for effects that are linear with respect to the Knudsen number. It is assumed that substances comprising droplet and liquid layer are identical, and it is taken into account that these substances can contain dissolved nonvolatile component whose concentration is so low that its presence should necessarily be accounted for only in the calculation of the concentration of saturated vapor. Vapor pressure at large distance from the droplet was assumed to be equal to the pressure of saturated vapor above the plane liquid surface. Results of numerical calculations of the rate of steady motion of water droplet evaporating or growing in the air are reported.

Direct allowance for the effects of thermodynamic nonideality in the quantitative characterization of protein self-association by osmometry

A procedure is described for the direct analysis of osmotic pressure data for reversibly dimerizing proteins that makes allowance for effects of thermodynamic nonideality on the statistical–mechanical basis of the potential-of-mean-force between molecules. Detailed consideration is also given to calculation of the magnitudes of the required virial coefficients. After illustration of the approach with analysis of simulated osmotic pressure data, the method is used to obtain dimerization constants from published osmotic pressure data for soybean proteinase inhibitor, hemoglobin and α-chymotrypsin.

Mathematical modeling of angular distortions in laser ranging of the RadioAstron satellite

A mathematical model for angular distortions in satellite laser ranging is constructed with allowance for effects of the theory of general relativity. For the RadioAstron mission satellite, it is shown that the angular distortions exceed the present-day accuracy of angular measurements in satellite laser ranging at all orbit points. Manifested most strikingly in the neighborhood of apogee, these distortions have to be taken into account in data processing performed within the framework of high-accuracy space exploration programs.

Magnetization curves of an isotropic superparamagnet and induced-blocking effect

Magnetization curves of a nanoparticle with a ferromagnetic intraparticle isotropic exchange interaction are calculated with allowance for effects of thermal deviations of atomic magnetic moments. These curves were shown to be located below magnetization curves obtained by the Neel theory of “rigid” paramagnetism that does not take into account thermal excitations of individual spins. A reductive heuristic formula that is suitable for calculating the magnetization curves of an isotropic superparamagnet in low magnetic fields is discussed. Temperatures of blocking of the total magnetic moment of an isotropic superparamagnetic nanoparticle have been estimated for the case of blocking induced by an applied magnetic field.

High-Precision Ephemerides of Planets—EPM and Determination of Some Astronomical Constants

The latest version of the planetary part of the numerical ephemerides EPM (Ephemerides of Planets and the Moon) developed at the Institute of Applied Astronomy of the Russian Academy of Sciences is presented. The ephemerides of planets and the Moon were constructed by numerical integration in the post-Newtonian metric over a 140-year interval (from 1880 to 2020). The dynamical model of EPM2004 ephemerides includes the mutual perturbations from major planets and the Moon computed in terms of General Relativity with allowance for effects due to lunar physical libration, perturbations from 301 big asteroids, and dynamic perturbations due to the solar oblateness and the massive asteroid ring with uniform mass distribution in the plane of the ecliptic. The EPM2004 ephemerides resulted from a least-squares adjustment to more than 317000 position observations (1913–2003) of various types, including radiometric measurements of planets and spacecraft, CCD astrometric observations of the outer planets and their satellites, and meridian and photographic observations. The high-precision ephemerides constructed made it possible to determine, from modern radiometric measurements, a wide range of astrometric constants, including the astronomical unit AU = (149597870.6960 ± 0.0001) km, parameters of the rotation of Mars, the masses of the biggest asteroids, the solar quadrupole moment J 2 = (1.9 ± 0.3) × 10−7, and the parameters of the PPN formalism β and γ. Also given is a brief summary of the available state-of-the-art ephemerides with the same precision: various versions of EPM and DE ephemerides from the Jet Propulsion Laboratory (JPL) (USA) and the recent versions of these ephemerides—EPM2004 and DE410—are compared. EPM2004 ephemerides are available via FTP at ftp://qua-sar.ipa.nw.ru/incoming/EPM2004.

Helicity generation in uniform helical flows

Helicity generation conditions are derived for helical flows of Joukowski type with allowance for effects due to viscosity, buoyancy, temperature nonuniformity, and solid-body rotation. The upper and lower limits are determined for the rotation-frequency interval in which helicity can be generated by viscous forces. These conditions correspond to the regime of an isolated tornado-like vortex. An exact solution to the time-independent equations of motion for inviscid incompressible flow is obtained. The solution describes a generalized Kelvin-Helmholtz vortex having the form of a localized cylindrical vortex with nontrivial stable topological vortex-core structure determined by a finite value of helicity. For linear traveling inertia waves, which must have uniform helical structure, a general representation is found that characterizes helical structures of different origin.

Allowance for thermodynamic non-ideality in the characterization of protein self-association by frontal exclusion chromatography: hemoglobin revisited

This investigation re-examines theoretical aspects of the allowance for effects of thermodynamic non-ideality on the characterization of protein self-association by frontal exclusion chromatography, and thereby provides methods of analysis with greater thermodynamic rigor than those used previously. Their application is illustrated by reappraisal of published exclusion chromatography data for hemoglobin on the controlled-pore-glass matrix CPG-120. The equilibrium constant of 100/M that is obtained for dimerization of the α 2β 2 species by this means is also deduced from re-examination of published studies of concentrated hemoglobin solutions by osmotic pressure and sedimentation equilibrium methods.

Mortality Related to Cold and Air Pollution in London After Allowance for Effects of Associated Weather Patterns

We looked for atypical weather patterns that could confound, and explain large inconsistencies in, conventional estimates of mortality due to SO2, CO, and smoke. Using Greater London data for 1976–1995 in the linear temperature/mortality range 0–15°C we determined weather patterns associated with pollutants (all deseasonalized) by single regressions of daily temperature, wind, rain, humidity, and sunshine at successive days advance and delay. Polluted days were colder (P<0.01 for SO2, CO, and smoke) and less windy and rainy than usual, and this cold weather was more prolonged than usual with 50% maximum temperature depression 5.9 days (95% interval 4.0–7.7) before high SO2, compared to 2.0 (1.6–2.3) days before average cold days. We also used multiple regression of mortality at 50+ years of age on all these weather factors and pollutants at 0-, 1-, 2- to 4-, 5- to 13-, and 14- to 24-day delays to allow for the atypical weather patterns. This showed cold weather associated with 2.77 excess deaths per million during 24 days following a 1°C fall for 1 day, but no net excess deaths with SO2 (mean 28.0 ppb) or CO (1.26 ppm). It suggested (P>0.05) some increase with smoke, perhaps acting as surrogate for PM10, for which data were too scanty to analyze.

Studies of solute self-association by sedimentation equilibrium: allowance for effects of thermodynamic non-ideality beyond the consequences of nearest-neighbor interactions

A sedimentation equilibrium study of α-chymotrypsin self-association in acetate-chloride buffer, pH 4.1 I 0.05, has been used to illustrate determination of a dimerization constant under conditions where thermodynamic non-ideality is manifested beyond the consequences of nearest-neighbor interactions. Because the expressions for the experimentally determinable interaction parameters comprise a mixture of equilibrium constant and excluded volume terms, the assignment of reasonable magnitudes to the relevant virial coefficients describing non-associative cluster formation is essential for the evaluation of a reliable estimate of the dimerization constant. Determination of these excluded volume parameters by numerical integration over the potential-of-mean-force is shown to be preferable to their calculation by approximate analytical solutions of the integral for this relatively small enzyme monomer with high net charge (+10) under conditions of low ionic strength (0.05 M).