System Of Spheres Research Articles

Excluded volume of the system of hard-core spheres revisited: New insights from computer simulations

The role of excluded volume in the equation of state of hard-sphere system is studied by analytical theory and computer simulations. The excluded-volume parameter b(ρ) introduced in the van der Waals equation is examined as a function of density. A number of approximations are considered and tested against Monte Carlo simulations. Parameter b(ρ) is seen to decline by a factor of 2 over the density range in which the system is still in the fluid state. Partial contributions of two- and three-sphere intersections to b(ρ) are analyzed as a function of density. The resulting series is seen to be converging very slowly. An approximation based on Padé approximants is seen to offer best accuracy at the lowest cost. It involves computation of the three lowest virial expansion coefficients B2,B3 and B4. Numerical tests reveal that this approximation is accurate in the case of ellipsoids and a number of hard-core polyhedra, supporting a potential application in phase equilibria studies of molecules with non-spherical shapes, such as cubes, pear-shaped molecules and so on.

The influence of behavioral risk factors on outcomes of students’ health

Introduction. Currently, there are not enough hygienic studies to identify causal relationships between health disorders and behavioural risk factors. The purpose of the study: to assess the influence of behavioural risk factors on students’ health outcomes. Materials and methods. The object of the study were one hundred nine students in grades 3-6. Questionnaires and comprehensive medical examinations were conducted. The research materials were statistically processed using non-parametric analysis methods, descriptive statistics and relative risk calculations. Results. Data were obtained on the leading behavioural risk factors of modern students (physical inactivity, lack of sleep, unhealthy diet, low school satisfaction, high aggressiveness in communication with peers. Functional deviations and chronic diseases of the musculoskeletal system, nervous system and mental sphere, eyes and digestive system were formed among students. There were identified three groups of behavioural risk factors: 1) use of digital devices; 2) social wellbeing in school; 3) regime of the day. Limitations. The study is limited to the study of the influence of only behavioral risk factors on the health of students, the time of observation, the use of self-questionnaires, which can lead to recall bias, affect the accuracy of data, with the possibility of overestimation or underestimation of data. Conclusion. Quantitative dependences of the development of the most common functional deviations and chronic diseases in students on risk behaviors in the children’s population have been established. This indicates the importance of high levels of prevalence of risky forms of behaviour and their underestimation in the formation of pathological conditions and the need for measures to correct behavior dangerous to the health of children and adolescents.

Early detection of Sclerotinia sclerotiorum on oilseed rape leaves based on optical properties

Oilseed rape ( Brassica napus L.) is susceptible to Sclerotinia sclerotiorum and its yield would reduce dramatically by the sclerotinia disease. Early detection of the pathogen to prevent the spread of sclerotinia is of great significance. In this paper, the optical response of oilseed rape leaves to Sclerotinia sclerotiorum was analyzed and a new method for early detection of sclerotinia disease based on optical properties was proposed. The optical absorption ( μ a ) and reduced scattering ( μ s ′ ) coefficients of healthy and infected (invisible-symptom and visible-symptom) oilseed rape leaves were measured by using a single integrating sphere (SIS) system over 500–1000 nm. Results showed that with the development of Sclerotinia sclerotiorum infection from healthy to visible-symptom leaves, μ a decreased in 600–700 nm that contained obvious absorption peaks by pigments, while μ s ′ increased in 500–1000 nm. Then linear discriminant analysis (LDA) and support vector machines (SVM) models were developed to discriminate infected leaves from healthy ones, with the raw data of μ a in 500–700 nm, μ s ′ in 500–700 nm, and ( μ a - μ s ′ ) in 600–700 nm, as well as corresponding effective wavelengths optimally selected by the successive projections algorithm (SPA). Results showed that the LDA models with the raw and SPA-selected data of μ a in 500–700 nm, and the SPA-selected ( μ a - μ s ′ ) data, and the SVM model with SPA-selected μ a data all provided 100.00% classification accuracy. Overall, this study proved that the optical properties of oilseed rape responded to Sclerotinia sclerotiorum at early stage, and could be a new basis for early detection of sclerotinia disease. • Optical absorption and scattering parameters were measured for oilseed rape leaves. • Optical response of oilseed rape leaves to Sclerotinia sclerotiorum was analyzed. • Optical parameters were optimally selected for Sclerotinia sclerotiorum detection. • Models for classifying infected and healthy oilseed rape leaves were developed. • Early detection of Sclerotinia sclerotiorum was achieved based on optical properties.

Exploring canyons in glassy energy landscapes using metadynamics

The complex physics of glass-forming systems is controlled by the structure of the low-energy portions of their potential energy landscapes. Here we report that a modified metadynamics algorithm efficiently explores and samples low-energy regions of such high-dimensional landscapes. In the energy landscape for a model foam, our algorithm finds and descends meandering canyons in the landscape, which contain dense clusters of energy minima along their floors. Similar canyon structures in the energy landscapes of two model glass formers-hard sphere fluids and the Kob-Andersen glass-allow us to reach high densities and low energies, respectively. In the hard sphere system, fluid configurations are found to form continuous regions that cover the canyon floors up to densities well above the jamming transition. For the Kob-Andersen glass former, our technique samples low-energy states with modest computational effort, with the lowest energies found approaching the predicted Kauzmann limit.

Communication System of Documentary Support of the Legal Sphere and State Unifi ed Documentation System: Features of the Relationship

Communication System of Documentary Support of the Legal Sphere and State Unifi ed Documentation System: Features of the Relationship

Reminiscences of Doug Henderson and hard spheres

This is a personal account of Doug Henderson as my PhD Adviser and our work together on hard sphere systems.

Optical characterization of liquid phantoms in 500–1000 nm using an improved single integrating sphere system

This paper reports on optical characterization (absorption coefficient μa and reduced scattering coefficient μs′) of liquid phantoms in the wavelength range of 500–1000 nm using an improved single integrating sphere system. 54 liquid optical phantoms (18 pure absorption, pure scattering and mixed samples each) with known optical properties were first prepared. The overall performance of a laboratory-established single integrating sphere system was then evaluated, and the results indicated that the system has perfect stability, repeatability, and accuracy in optical property measurement. After that, effect of cuvette size (i.e., optical path and wall thickness) on optical property measurement was investigated. The experimental results showed that the discrepancies of the measured optical properties for the pure absorption and scattering phantoms held by different cuvettes with varying optical paths and wall thicknesses were within 8.76 %. Finally, the effect of different concentrations of absorber and scatterer on optical property determination of mixed liquid phantoms were explored. It was found the measured optical properties of the mixed liquid phantoms had a considerable difference from those of the pure absorption and pure scattering phantoms. We guessed that the addition of the absorber (scatterer) would dilute the concentration level of scatterer (absorber), and also brought about interaction between the two particles, and thus resulting in an offset for the measured optical properties. Future work needs to test our conjecture from the micro level, like monitoring the dynamic change of the absorption and scattering particle distribution and interaction, when optically characterizing the mixed liquid phantoms.

Diffusion and velocity correlations of the phase transitions in a system of macroscopic rolling spheres - Dataset

Diffusion and velocity correlations of the phase transitions in a system of macroscopic rolling spheres - Dataset

Diffusion and velocity correlations of the phase transitions in a system of macroscopic rolling spheres - Dataset

Diffusion and velocity correlations of the phase transitions in a system of macroscopic rolling spheres - Dataset

Short-Time Transport Properties of Bidisperse Suspensions of Immunoglobulins and Serum Albumins Consistent with a Colloid Physics Picture.

The crowded environment of biological systems such as the interior of living cells is occupied by macromolecules with a broad size distribution. This situation of polydispersity might influence the dependence of the diffusive dynamics of a given tracer macromolecule in a monodisperse solution on its hydrodynamic size and on the volume fraction. The resulting size dependence of diffusive transport crucially influences the function of a living cell. Here, we investigate a simplified model system consisting of two constituents in aqueous solution, namely, of the proteins bovine serum albumin (BSA) and bovine polyclonal gamma-globulin (Ig), systematically depending on the total volume fraction and ratio of these constituents. From high-resolution quasi-elastic neutron spectroscopy, the separate apparent short-time diffusion coefficients for BSA and Ig in the mixture are extracted, which show substantial deviations from the diffusion coefficients measured in monodisperse solutions at the same total volume fraction. These deviations can be modeled quantitatively using results from the short-time rotational and translational diffusion in a two-component hard sphere system with two distinct, effective hydrodynamic radii. Thus, we find that a simple colloid picture well describes short-time diffusion in binary mixtures as a function of the mixing ratio and the total volume fraction. Notably, the self-diffusion of the smaller protein BSA in the mixture is faster than the diffusion in a pure BSA solution, whereas the self-diffusion of Ig in the mixture is slower than in the pure Ig solution.

Calculation of interfacial free energy for binary hard sphere mixtures

In this work, we present a method to calculate interfacial free energy for a binary hard sphere fluid mixture in coexistence with disordered face centered cubic solid. Monte Carlo(MC) Simulations are performed at 0.97 size ratio of small to large particle diameters. Interfacial free energy is calculated across composition for (100),(110) and (111) orientations of the substitutionally disordered solid phase along the coexistence line. Our calculations are based on the concept of Gibbs equimolar dividing surface. First, we calculate the surface excess quantities using the thermodynamic properties obtained from MC simulations then we integrate rewritten equivalent form of Gibbs adsorption equation with respect to pressure using pure hard sphere system interfacial free energy as a reference to get binary hard sphere mixture interfacial free energy. In our simulations we also varied cross sectional areas of solid exposed to fluid mixtures by varying system sizes, the computed interfacial free energies are consistent within error limits and confirms to scaling laws.

Simple fluid with broken time-reversal invariance.

We characterize a system of hard spheres with a simple collision rule that breaks time-reversal symmetry but conserves energy. The collisions lead to an achiral, isotropic, and homogeneous stationary state whose properties are determined in simulations and compared to an approximate theory originally developed for elastic hard spheres. In the nonequilibrium fluid state, velocities are correlated, a phenomenon known from other nonequilibrium stationary states. The correlations are long-ranged decaying like 1/r^{D} in D dimensions. Such correlations are expected on general grounds far from equilibrium and had previously been observed in driven or nonstationary systems.

Collective excitations in jammed states: ultrafast defect propagation and finite-size scaling

In crowded systems, particle currents can be mediated by propagating collective excitations which are generated as rare events, are localized, and have a finite lifetime. The theoretical description of such excitations is hampered by the problem of identifying complex many-particle transition states, calculation of their free energies, and the evaluation of propagation mechanisms and velocities. Here we show that these problems can be tackled for a highly jammed system of hard spheres in a periodic potential. We derive generation rates of collective excitations, their anomalously high velocities, and explain the occurrence of an apparent jamming transition and its strong dependence on the system size. The particle currents follow a scaling behavior, where for small systems the current is proportional to the generation rate and for large systems given by the geometric mean of the generation rate and velocity. Our theoretical approach is widely applicable to dense nonequilibrium systems in confined geometries. It provides new perspectives for studying dynamics of collective excitations in experiments.

Differences in optical properties and internal qualities of ‘Fuji’ apple produced in different areas of the Loess Plateau region

Present studies have shown that near-infrared spectroscopy (NIRS) could be used to identify the producing area of apple. However, we still do not know whether the producing area affects the optical properties of apple, whether it affects the relationship between optical properties and internal qualities, and whether the optical parameters could be used to predict the apple-producing area. To answer these questions, the apples produced in three areas with different temperatures, precipitations, and altitudes in the Loess Plateau region, China, were used as samples to obtain the optical properties of apple pulp by a single integrating sphere system, analyze the differences in optical properties of apples produced in different areas, analyze the correlations between optical properties (absorption coefficient (μa) and reduced scattering coefficient (μs')) and internal quality indices (soluble solids content (SSC), moisture content and firmness), and investigate the feasibility of discriminating the apples produced in different areas and predicting the internal qualities using NIRS. The results showed that the apples produced in Luochuan had the highest SSC while Yangling apples had the highest moisture content. The μa had three absorption peaks at around 985, 1200, and 1430 nm, and the μs' of apples from three areas showed a similar trend with wavelength. The best correlation of μa with SSC and moisture content was found in Yangling apples with a correlation coefficient of −0.90 and 0.79, respectively. The built linear discriminant analysis based on μa spectra performed better in discriminating producing area. The established partial least squares regression models based on μa spectra had the best prediction performance for SSC and moisture content, while the model built with μs' had the best prediction performance for firmness. This study is helpful to understand the differences in optical property of ‘Fuji’ apple produced in different areas and offers information for identifying the producing area of fruit using NIRS technology.

Enhancing luminous flux and color rendering of laser-excited YAG:Ce3+ single crystal phosphor plate via surface roughening and low-temperature sintering a CaAlSiN3:Eu2+ phosphor-in-borate glass

Y3Al5O12:Ce3+ (YAG:Ce3+) single crystal phosphor (SCP) exhibits high internal quantum efficiency (IQE) and excellent thermal conductivity and stability. Such properties are promising in high-power laser-excited white lighting applications. However, YAG:Ce3+ SCP usually shows low luminous flux and color rendering index (CRI, Ra) when excited by a transmissive laser. In this study, a self-designed three-integrating sphere system was established to characerize the optical performances of YAG:Ce3+ SCP palates under both the reflective and transmissive 455 nm blue laser excitations. Next, its luminous and color rendering properties under transmissive laser excitation were improved by surface roughening treatment and sintering of a CaAlSiN3:Eu2+ (CASN:Eu2+) phosphor-in-borate glass (PiBG) layer. The results revealed that: (1) When the YAG:Ce3+ SCP was excited by blue laser, its forward luminous flux was considerably lower than the backward one; (2) Under transmissive excitation, its luminous flux rolled up with the maximum increase rate of 109.19% when the averaged roughness (Ra) increased from 0.35 to 5.40 μm; (3) After sintering the CASN:Eu2+ PiBG layer on the roughening YAG:Ce3+ SCP, its luminous flux, CRI increased by 31.48% and 117.14%, and its color fidelity index (CFI, Rf) reached up to 82 under the transmissive 3.03 W blue laser excitation.

Five-dimensional Poincaré sphere system for representing azimuthally varying vector optical fields

Vector optical fields (VOFs) with space-variant polarization on the wave front, have attracted considerable attention and have been applied in many realms from focal engineering to light-matter interaction. Recently, some upgraded Poincar\'e sphere (PS) models have been presented to describe VOFs, providing new insights in studying and applying structured light. Here, we report a model of five-dimensional (5D) PS system consisting of a series of three-dimensional (3D) spheres (Bloch spheres) located on a two-dimensional (2D) plane. In fact, this model is geometrically similar to the solar system, and the 3D Bloch spheres and the 2D plane are analogous to the ``planets'' and their orbital plane, respectively. This model is the most generalized model describing the azimuthally varying VOFs we know so far. A reliable and flexible experimental scheme is exploited to generate the VOFs represented by the 5D PS system. Furthermore, the 5D PS system is a complete tool to represent the azimuthally varying VOFs with polarization changing along arbitrary circular path on any 3D PS, and can be implemented for representing and designing the spin and orbital angular momenta. The 5D PS system graphically simplifies the representation of complex structured light and provides a prominent toolkit to the design and application of VOFs as well as the corresponding optical angular momentum.

Forming a therapeutic sphere to treat ailments using optimization techniques

AbstractRecently, National Geographic published a special bookazine titled Nature's Best Remedies. This bookazine reorganized nature's remedies as a therapeutic table for treating ailments. The table provides considerable knowledge but is inconvenient to use. This study converts the therapeutic table into a therapeutic sphere by using optimization techniques. In the therapeutic sphere, similar ailments are clustered together, and remedies related to specified ailments are allocated on the sphere. Two surveys demonstrated that, compared with the therapeutic table, the therapeutic sphere is more convenient to use, more efficient for making queries, and more useful for healthcare as well as more intuitive. The proposed therapeutic sphere system can be accessed at http://140.113.73.198/gbball/examples/medeng2.aspx.

War-adjustment problems faced by the Ukrainians who appeared in the TV program "Psychologist's Help"

Introduction. Russia's full-scale war in Ukraine gave Ukrainians a wide range of experiences. Besides the individuals' emotional sphere, their cognitive, behavioral, motivational, value, physiological, and physical systems were also affected. Interference in the psychological and physiological systems directly affects individuals' adjustment to social, territorial, individual, and physical changes. The war acts as a high-intensity stressor whose prolonged influence can cause maladjustment. Aim. To explore the psychological problems of adjustment to the war faced by the Ukrainians who appeared in the TV program called "Psychologist's Help" and the ways of solving them. Methods. Interviews, feedback, as well as psychotherapeutic methods used in the TV program: cognitive-behavioral approach, Gestalt approach, art therapy, symbol-drama, metaphorical cards, work with images and metaphors, etc. Results. There were identified 20 general problems faced by the TV program participants who were divided into four categories: refugee women with children who moved abroad; women with children who stayed in Ukraine; refugee women who were single; men who stayed in Ukraine and did not join the army. The greatest adjustment difficulties were faced by the women with children who remained in Ukraine (they were uтder the constant pressure of war stressors). Refugee women with children who moved abroad had adjustment difficulties because of poor housing conditions, forced staying with strangers, and language barriers. Certain cognitive and behavioral techniques helped the TV program guests control their emotions and improve their physical and psychological conditions. Conclusions. Most problems of the program participants related to the war-caused difficulties of adjustment to the new social environment and their emotional, cognitive, behavioral, physical, physiological, and professional issues. The Psychologist's Help is a popular TV program whose advice can be helpful for TV viewers with war-related psychological problems.

La cosmología aristotélica y su influencia en la astrología de la baja edad media

Aristotelian cosmology and physics received by the medieval occident justify the scientific view of the (medieval) astrology. How so? Well, let’s consider the aristotelic theory of the tripartite man: body, soul and pneuma (as the link between both and as the reason of the ability of the soul to catch inmaterial knowledge from the material one). Now, let’s consider the aristotelian view of the cosmos as a system of celestial spheres –moved by the Unmoved mover – and that influences on earth in a way that they produce its movement. These two prior considerations will serve as a support to talk about the relation man-cosmos throughtout the pneuma (made from the aristotelian quintessence, the eter). This view, altogether, will be useful to justify some medieval views about the astrology as a scientific discipline, as starting in natural philosophy. Once this cosmological system falls, the magic-astrological believes that were supported by so will subsequently lose their epistemic-scientific level.

Topological Order in an Antiferromagnetic Tetratic Phase.

We study lattice melting in two-dimensional systems of spinful particles that interact antiferromagnetically. We argue that, for strong spin interactions, single lattice dislocations are forbidden by magnetic frustration. This leads to a melting scenario in which a tetratic phase, containing free dislocation pairs and bound disclinations, separates the solid from the liquid. We demonstrate this phase numerically in a system of hard spheres confined between parallel plates, where spins are represented by the heights of the spheres. In the tetratic phase, the spins are shown to be as antiferromagnetically ordered as allowed by their spatial configuration.