Refraction difference value variations in children and adolescents with different refractive errors

AIM:To evaluate the refraction difference value(RDV)variations in children and adolescents with different refractive errors and analyze its correlation with refractive development.METHODS:Participants aged 4-16y with different refractive statuses(hyperopia,emmetropia,myopia)underwent comprehensive eye examinations,including spherical equivalent(SE)refraction,axial length(AL),total RDV(TRDV),and RDVs at various eccentricities(0°-15°,15°-30°,30°-45°)and quadrants(inferior,superior,nasal,temporal).Statistical analysis involved one-way ANOVA for group comparisons and Pearson correlation for examining relationships between SE/AL and RDVs.Paired t-tests compared quadrant-specific RDVs within groups.RESULTS:Significant difference was found in TRDV(P<0.001),RDV15°-30°(P=0.033),RDV30°-45°(P<0.001),RDV-inferior(RDV-I,P<0.001)and RDV-temporal(RDV-T,P<0.001)among hyperopia,emmetropia and myopia group.Pearson correlation analysis revealed a negative correlation of SE with TRDV(P=0.001),RDV30°-45°(P=0.004),RDV-I(P=0.047),and RDV-T(P<0.001).The differences between RDV-superior(RDV-S)and RDV-I were statistically significant in all groups(P<0.001 for all)and between RDV-T and RDV-nasal(RDV-N)were statistically significant in hyperopia group(P<0.001).Within the premyopic group,the analysis revealed a negative correlation of SE with RDV-I(P=0.009).Pearson correlation analysis revealed a positive correlation of AL with TRDV(P=0.036),RDV15°-30°(P=0.004),RDV30°-45°(P<0.001),RDV-S(P=0.003),RDV-I(P<0.001),RDV-T(P<0.001),RDV-N(P=0.022),while revealed a negative correlation of AL with RDV0-15°(P=0.018).CONCLUSION:Our study indicates TRDV,RDV30°-45°,RDV-I,RDV-T may relate to refractive development,and a negative correlation between SE and RDV-I in pre-myopic children.

Differences Between British and Americans’ Cultures in Values

Values are the most important issue in identifying one particular culture.Social values are the feelings people have about what is important,worthwhile,and just.In this paper,the differences between British and American values are discussed in two aspects which mainly lie respectively in the comparisons of values and characteristics in both cultures.

An Analysis of Value Differences in English and Chinese Idioms from the Perspective of Intercultural Communication

Idioms are the essence and gems of human wisdom and an important carrier of national culture. As a special form of language, they play an important role in intercultural communication. Due to the uniqueness of each culture, English and Chinese idioms are different in many aspects, values included. The present paper attempts to analyze the different values in English and Chinese idioms from three aspects: dependence vs independence, past-time orientation vs future-time orientation, and harmony vs competition. And the authors hope that it will be of some practical significance in people's intercultural communication.

Land Use Dynamics and Ecosystem Service Value Changes in the Yangtze River Delta Urban Agglomeration Under Different Scenarios

Urban agglomerations,serving as pivotal centers of human activity,undergo swift alterations in ecosystem services prompted by shifts in land utilization.Strengthening the monitoring of ecosystem services in present and future urban agglomerations contributes to the rational planning of these areas and enhances the well-being of their inhabitants.Here,we analyzed land use conversion in the Yangtze River Delta(YRD)urban agglomeration during 1990-2020 and discussed the spatiotemporal response and main drivers of changes in ecosystem service value(ESV).By considering the different development strategic directions described in land use planning policies,we predicted land use conversion and its impact on ESV using the Future Land Use Simulation(FLUS)model in three scenari-os in 2025 and 2030.Results show that:1)from 1990 to 2020,land use change is mainly manifested as the continuous expansion of con-struction land to cultivated land.Among the reduced cultivated land,82.2%were occupied by construction land.2)The land use types conversion caused a loss of 21.85 billion yuan(RMB)in ESV during 1990-2020.Moreover,the large reduction of cultivated land area led to the continuous decline of food production value,accounting for 13%of the total ESV loss.3)From 2020 to 2030,land use change will mainly focus on Yangzhou and Zhenjiang in central Jiangsu Province and Taizhou in southern Zhejiang Province.Under the BAU(natural development)and ED(cultivated land protection)scenarios,construction land expansion remains dominant.In contrast,under the EP(ecological protection)scenario,the areas of water bodies and forest land increase significantly.Among the different scenarios,ESV is highest in the EP scenario,making it the optimal solution for sustainable land use.It can be seen that the space use conflict among urban,agriculture and ecology is a key factor leading to ESV change in the urban agglomeration of Yangtze River Delta.There-fore,it is crucial to maintain spatial land use coordination.Our findings provide suggestions for scientific and rational land use planning for the urban agglomeration.

SUPERCONVERGENCE OF GENERALIZED DIFFERENCE METHOD FOR ELLIPTIC BOUNDARY VALUE PROBLEM

Some superconvergence results of generalized difference solution for elliptic boundary value problem are given. It is shown that optimal points of the stresses for generalized difference method are the same as that for finite element method.

Characteristic finite difference method and application for moving boundary value problem of coupled system

The coupled system of multilayer dynamics of fluids in porous media is to describe the history of oil-gas transport and accumulation in basin evolution.It is of great value in rational evaluation of prospecting and exploiting oil-gas resources.The mathematical model can be described as a coupled system of nonlinear partial differential equations with moving boundary values.A kind of characteristic finite difference schemes is put forward,from which optimal order estimates in l~2 norm are derived for the error in the approximate solutions.The research is important both theoretically and practically for the model analysis in the field,the model numerical method and software development.

SCISSORS DIFFERENCE AND ITS IMPACTS ON ECONOMIC VALUE OF CULTIVATED LAND IN CHINA

The problem of price scissors difference between industrial products and agricultural products is one of the important problems in China. It impacts not only the living standard improvement of farmers but also the economic value of cultivated land, furthermore results in the direct and indirect loss of cultivated land resources. China＇s cultivated land area has decreased dramatically in recent years. An important reason for the decrease is the relatively low cost of cultivated land occupancy, which results from the distortion of economic value of cultivated land due to the existence of scissors difference. This study firstly analyzed the dynamic change of scissors difference and calculated the absolute and relative magnitude of scissors difference from 1997 to 2002, then computed the economic value of cultivated land before and after scissors difference adjustment in 2002, and finally discussed the inverted scissors difference. Results suggest that the scissors difference has a remarkable impact on the economic value of cultivated land, and the adjustment of scissors difference even inverted scissors difference to the economic value of cultivated land is indisoensable.

VALUE DISTRIBUTION OF MEROMORPHIC SOLUTIONS OF CERTAIN NON-LINEAR DIFFERENCE EQUATIONS

In this article, we consider the non-linear difference equation(f(z + 1)f(z)-1)(f(z)f(z-1)-1) =P(z, f(z))/Q(z, f(z)),where P(z, f(z)) and Q(z, f(z)) are relatively prime polynomials in f(z) with rational coefficients. For the above equation, the order of growth, the exponents of convergence of zeros and poles of its transcendental meromorphic solution f(z), and the exponents of convergence of poles of difference △f(z) and divided difference △f(z)/f(z)are estimated. Furthermore, we study the forms of rational solutions of the above equation.

Further Results on Meromorphic Functions and Their nth Order Exact Differences with Three Shared Values

Let E(a;f) be the set of a-points of a meromorphic function f(z) counting multiplicities. We prove that if a transcendental meromorphic function f(z) of hyper order strictly less than 1 and its nth exact difference Δnc f(z) satisfy E(1;f)= E(1;Δnc f), E(0;f) E(0;Δnc f) and E(1;f) E(1;Δnc f), then Δnc f(z) f(z). This result improves a more recent theorem due to Gao et al.(Gao Z, Kornonen R, Zhang J, Zhang Y. Uniqueness of meromorphic functions sharing values with their nth order exact differences. Analysis Math., 2018, https://doi.org/10.1007/s10476- 018-0605-2) by using a simple method.

A UNIFORMLY CONVERGENT FINITE DIFFERENCE METHOD FOR A SINGULARLY PERTURBED INITIAL VALUE PROBLEM

Initial value problem for linear second order ordinary differential equation with small parameter by the first and second derivatives is considered. An exponentially fitted difference scheme with constant fitting factors is developed in a uniform mesh, which gives first_order uniform convergence in the sense of discrete maximum norm. Numerical results are also presented.

THE UPWIND FINITE DIFFERENCE METHOD FOR MOVING BOUNDARY VALUE PROBLEM OF COUPLED SYSTEM

Coupled system of multilayer dynamics of fluids in porous media is to describe the history of oil-gas transport and accumulation in basin evolution.It is of great value in rational evaluation of prospecting and exploiting oil-gas resources.The mathematical model can be described as a coupled system of nonlinear partial differential equations with moving boundary values.The upwind finite difference schemes applicable to parallel arithmetic are put forward and two-dimensional and three-dimensional schemes are used to form a complete set.Some techniques,such as change of variables,calculus of variations, multiplicative commutation rule of difference operators,decomposition of high order difference operators and prior estimates,are adopted.The estimates in l~2 norm are derived to determine the error in the approximate solution.This method was already applied to the numerical simulation of migration-accumulation of oil resources.

AN EXPONENTIALLY FITTED DIFFERENCE SCHEME FOR THE HYPERBOLIC-HYPERBOLIC SINGULARLY PERTURBED INITIAL-BOUNDARY VALUE PROBLEM

In this paper we discuss, an initial-boundary value problem of hyperbolic type with first derivative with respect to x. The asymptotic solution is constructed and its uniform validity is proved under weader compatibility conditions. Then we develop an exponentially fitted difference scheme and establish discrete energy inequality. Finally, we prove that the solution of difference problem uniformly converges to the solution of the original problem.

A UNIFORMLY DIFFERENCE SCHEME OF SINGULAR PERTURBATION PROBLEM FOR A SEMILINEAR ORDINARY DIFFERENTIAL EQUATION WITH MIXED BOUNDARY VALUE CONDITION

In the poper, the method of separating singularity is applied to study the uniformly difference scheme of a singular perturbation problem for a semilinear ordinary differential equation with mixed boundary value condition. The uniform convergence on small parameter ε of order one for an IVin type difference scheme constructed is proved. At the end of the paper, a numerical example is given. The computing results coincide with the theoretical analysis.

Modified characteristic finite difference fractional step method for moving boundary value problem of nonlinear percolation system

A fractional step scheme with modified characteristic finite differences run- ning in a parallel arithmetic is presented to simulate a nonlinear percolation system of multilayer dynamics of fluids in a porous medium with moving boundary values. With the help of theoretical techniques including the change of regions, piecewise threefold quadratic interpolation, calculus of variations, multiplicative commutation rule of differ- ence operators, multiplicative commutation rule of difference operators, decomposition of high order difference operators, induction hypothesis, and prior estimates, an optimal order in 12 norm is displayed to complete the convergence analysis of the numerical algo- rithm. Some numerical results arising in the actual simulation of migration-accumulation of oil resources by this method are listed in the last section.

A Compact Difference Scheme for Multi-point Boundary Value Problems of Heat Equations

In this paper,a compact difference scheme is established for the heat equations with multi-point boundary value conditions.The truncation error of the difference scheme is O(τ2+h^4),where t and h are the temporal step size and the spatial step size.A prior estimate of the difference solution in a weighted norm is obtained.The unique solvability,stability and convergence of the difference scheme are proved by the energy method.The theoretical statements for the solution of the difference scheme are supported by numerical examples.

Normal values of flash visual evoked potentials in rabbits: Differences between the sexes and the eyes

BACKGROUND: The wave form, latency and wave amplitude of visual evoked potentials (VEP) are obviously affected by the stimulative parameters, physiological status of the subjects and anesthetics, thus there are greater normal variations and individual differences. The features of flash VEP (F-VEP) are to be observed. OBJECTIVE: To observe and compare the differences of F-VEP latencies and wave amplitudes between eyes in rabbits, and investigate the correlation with sex and the side of eyes. DESIGN: A comparative animal experiment. SETTING: Department of Neurosurgery, General Hospital of Chinese PLA. MATERIALS: The experiment was carried out in the neurophysiological laboratory of the Institute of Neurosciences, General Hospital of Chinese PLA from September 2004 to February 2005. Thirty big-ear rabbits of clean degree, 15 males and 15 females, weighing 2.0-2.5 kg, were provided by the animal center of the General Hospital of Chinese PLA. METHODS: Viking-IV perioperative monitor and flash stimulator for special use were applied. The rabbits were anesthetized with intramuscular injection of compound ketamine. The recording electrode was placed at 3 mm anterior to exoccipital tuberosity (onion, Oz), and the reference electrode was placed at the ear edge of the same side. The stimulative frequency was 1.9 Hz, and the amplifier was 50 μV; The range of wave filter was 5 Hz for high pass and 100 Hz for low pass; The average overlapping was 200 times, and the analytical time was 250 ms. MAIN OUTCOME MEASURES: Comparison of F-VEP wave forms; F-VEP latencies and wave amplitudes. RESULTS: All the 30 rabbits were involved in the analysis of results. ① Comparison of F-VEP wave forms in rabbits: The F-VEP waves mainly manifested as positive-negative-positive (PNP). The F-VEP manifestations to light stimulations were extremely similar between left and right eyes, and the wave amplitudes of both eyes were obviously increased. ② Determinations of F-VEP latencies and wave amplitudes: There were no significant differences in the latencies and wave amplitudes of F-VEP between the two groups (P > 0.05), the latencies of P1, N1 and P2 waves of left eye were (32.59±2.01), (43.85±4.35) and (66.20±8.13) ms, respectively, and the wave amplitudes of P1, N1 and P2 waves of left eye were (16.45±10.22), (7.93±3.56) and (17.62±8.18) μV. F-VEP latencies were stable with small changes, whereas amplitudes had greater changes. CONCLUSION: ① The latency and wave amplitudes F-VEP were stable with good repetition. ② The latencies and wave amplitudes had no significant differences between males and females, as well as between left and right eyes. Further investigation should be undertaken on the animal and clinical field.

Terminating Cycles for Iterated Difference Values of Four—Digit Integers

1. Introduction Since D. R. Kaprekar discoverd the interesting property of the number 6174 an interesting mathematical model has been developed:

ON WELL-CONDITIONED BOUNDARY VALUE PROBLEMS FOR SYSTEMS OF SECOND ORDER DIFFERENCE EQUATIONS

In this paper well-conditioning of boundary value problems for systems of second order difference equa-tions is studied.First,a sufficient condition for the existence of a unique bounded solution (for large enough number of steps) of an associated homogeneous system is given.Finally,a sufficient condition for well-condi-tioning,intrinsically related to the problem data is proposed.

THE VALUE DISTRIBUTION AND UNIQUENESS OF ONE CERTAIN TYPE OF DIFFERENTIAL-DIFFERENCE POLYNOMIALS

In this article, we investigate the distribution of the zeros and uniqueness of differential-difference polynomialsG（z）=（f^n（f^m（z）-1）∏j=1^d f（z＋cj）^vj）^（k）-α（z）,H（z）=（f^n（f（z）-1）^m∏j=1^d f（z＋cj）^vj）^（k）-α（z）,where f is transcendental entire function of finite order, cj（j = 1,2,…,d）, n,m,d, and vj（j = 1, 2,… , d） are integers, and obtain some theorems, which extended and improved many previous results.

Iterative Technology in a Singular Fractional Boundary Value Problem with q -Difference

In this paper, we apply the iterative technology to establish the existence of solutions for a fractional boundary value problem with q-difference. Explicit iterative sequences are given to approxinate the solutions and the error estimations are also given.