Service and cost benefits through clicks-and-mortar integration: Implications for the centralization/decentralization debate

Traditional “Brick-and-Mortar” operations face the challenge of adapting to a new set of competitive rules made necessary by consumers who want the option of ordering electronically via the Internet. To satisfy these customers, firms must develop strategies that integrate their standard retail in-store channel with this relatively new on-line channel. Therefore, this research is designed to provide insights into supply chain inventory management strategies relevant to “Clicks-and-Mortar” firms trying to satisfy both on-line and in-store sales. Specifically, this work considers the total cost implications of various inventory allocation strategies while maintaining target customer service levels. Analysis focuses on the development of models capable of handling new operating strategies made possible by electronic commerce. The implications of inventory risk pooling are considered in depth, revealing the existence of characteristics that determine whether completely centralized or decentralized policies are preferable.     

Application of the linear principle for the strongly-correlated variables: Calculations of differences between spectra

In this paper the authors suggest a new method of detection of possible differences between similar near infrared (NIR) spectra based on the self-similar (fractal) property. This property is a general characteristic that belongs to a wide class of the strongly-correlated systems. As an example we take a set of NIR spectra measured for three systems: (1) glassy carbon (GC) electrodes, (2) GC electrodes affected by azobenzene (AB) substance and finally (3) films (AB-FILM). Besides the physical model that should describe the intrinsic properties of these substances we found the fitting function that follow from the linear principle for the strongly-correlated variables. This function expressed in the form of linear combination of 4 power-law functions describes with the high accuracy the integrated curves that were obtained from the averaged values of the initially measured spectra. The nine fitting parameters can be considered as the quantitative “finger prints” for detection of the differences between similar spectra. Besides this result we established the self-similar behavior of the remnant functions. In other words, the difference between the initially integrated function and its fitting function can be expressed in the form of linear combinations of periodical functions having a set of frequencies following to relationship ω(k) = ω₀ξ^k, where the initial frequency ω₀ and scaling factor ξ are determined by the eigen-coordinates method. This behavior in the NIR spectra was discovered in the first time and physical reasons of such behavior merit an additional research.     

Static versus dynamic DEA in electricity regulation: the case of US transmission system operators

In this paper a dynamic DEA-model (data envelopment analysis) is developed that takes up Nemoto and Goto’s (Econ Lett 64(1):51–56, 1999) concept of quasi-fixed inputs but can dispense with price-information as it solely deals with technical efficiencies that are derived in an additive-model type of setting. This model is applied to the data of 50 of the largest US electric transmission system operators in the period 2000–2006 in order to show that the static DEA-models that are usually employed by electricity regulators can lead to wrong conclusions about the enterprises’ efficiency since they ignore the short-run fixity of essential inputs like transmission lines.     

Incentive regulation and the change in productive efficiency of local exchange carriers

Incentive regulation is now an important regulatory tool in the telecommunications industry in the United States. The issue that is explored here is whether incentive regulation in the form of a price cap for interstate access service to local loops has resulted in an increase in productive efficiency. The methodology for measuring the effects of incentive regulation on productive efficiency is data envelopment analysis (DEA). The results of empirically implementing the DEA approach indicate that most local exchange carriers (LECs) were technically efficient over the 1988–1998 period. Three LECs, however, consistently demonstrate scale inefficiency while two LECs show continued improvement in scale efficiency, attaining optimal scale efficiency by 1998. Finally, in the aggregate, there is a small, but clearly identifiable, improvement in aggrega LECs' technical efficiency (TE) between 1988 and 1998. This sort of improvement is precisely what incentive regulation in the form of price caps was designed to promote.     

Understanding the differences between single- and multiobjective optimization for the conservation of multiple species

The purpose of this study is to understand how solutions from single- and multiobjective optimization for the conservation of multiple species are different and what impacts these differences. We identify optimal conservation investment allocations maximizing expected species' habitat ranges for multiple pairs of species using two approaches in the central and southern Appalachian region. We find that disparities between the two approaches are affected by differences in the involved species' expected habitat ranges (i.e., contrasting and similar) and their correlation pattern (i.e., positive, negative, and insignificant). Using a single metric by aggregating species' habitats for multiple species to carry out single-objective optimization is shown to favor the species with a larger habitat distribution more if the involved species' expected habitat distributions are negatively correlated and their distribution difference is larger. Framing multiple metrics of species' habitats separately using multiobjective optimization for the same set of multiple species, in contrast, does not show such a drastic disparity.     

Measuring the joint impact of governance form and economic regulation on airport efficiency

This paper examines the joint impact that governance structure and economic regulation has on airport efficiency. The previous literature has focused on one or the other of these factors but not both. The empirical investigation uses a semi-parametric Bayesian distance stochastic frontier model, as well as a Data Envelopment Analysis (DEA) model. Based on a panel of airports in several countries we find that the form of economic regulation is relatively more important than the type of governance in affecting efficiency. The article provides measures of changes in expected efficiency when either or both the governance form and price regulation changes.     

Two methods for direct numerical integration of the Prandtl equation and comparative analysis between them

Two methods based on quadrature formulas are proposed for the direct numerical integration of Prandtl’s singular integrodifferential equation. In the first method, Prandtl’s equation is solved directly by applying the method of mechanical quadrature and the circulation along an airfoil section is determined. In the second method, Prandtl’s equation is rewritten for the circulation derivative, which is determined by applying mechanical quadratures, and the circulation is then reconstructed using the same quadrature formulas. Both methods are analyzed numerically and are shown to converge. Their convergence rates are nearly identical, while the second method requires much more CPU time than the first one.     

国际黄金期价与美元指数交互关系的多重分形分析

由于美元是国际黄金市场的主要标价货币,其币值的变化与国际金价的波动密切相关。本文利用多重分形分析法研究纽约商品交易所黄金期货价格数据与美元指数之间的交互相关性及两者的内部结构特征,并使用分形特征统计量度量市场风险大小。结果表明,虽然黄金期价和美元指数的收益率序列之间存在长期的负相关关系,但这种负相关关系是非线性动态变化的,具有多重分形特征,多重分形强度是时变性的,意味着市场风险大小随时间的不同而改变。     

A relation between the output regulation and the observer design for nonlinear systems

Output regulation and observer design are two important problems for nonlinear systems, and there is a vast literature addressing each problem separately in the control literature. Isidori and Byrnes [1] have solved the output regulation problem for nonlinear systems with a Poisson stable exosystem, and Sundarapandian [2] has solved the exponential observer design problem for Lyapunov stable nonlinear systems. In this paper, we demonstrate that for a special class of Lyapunov stable nonlinear systems, namely neutrally stable systems, the exponential observer design problem can be solved by converting it into an output regulation problem and then solving the new problem using the output regulation techniques of Isidori and Byrnes [1]. Finally, we present the corresponding results for the discrete-time case.     

Cost efficiency and scale economies in general dental practices in the US: a non-parametric and parametric analysis of Colorado data

This paper uses both the non-parametric method of data envelopment analysis (DEA) and the econometric method of stochastic frontier analysis (SFA) to study the production technology and cost efficiency of the US dental care industry using practice level data. The American Dental Association 2006 survey data for a number of general dental practices in the state of Colorado in the US are used for the empirical analysis. The findings suggest that the cost efficiency score is between 0.79 and 0.87, on average, and the cost inefficiency is mostly due to allocative rather than technical inefficiency. The optimal output level for a dental practice to fully exploit the economies of scale is estimated to be at $1.68 million. Average cost at this level of output is 50.6 cents for each dollar of gross billing generated. The DEA and SFA approaches provide generally consistent results.     

On the differences between Szeged and Wiener indices of graphs

Let G be a connected graph and η(G)=Sz(G)−W(G), where W(G) and Sz(G) are the Wiener and Szeged indices of G, respectively. A well-known result of Klav?ar, Rajapakse, and Gutman states that η(G)≥0, and by a result of Dobrynin and Gutman η(G)=0 if and only if each block of G is complete. In this paper, a path-edge matrix for the graph G is presented by which it is possible to classify the graphs in which η(G)=2. It is also proved that there is no graph G with the property that η(G)=1 or η(G)=3. Finally, it is proved that, for a given positive integer k,k≠1,3, there exists a graph G with η(G)=k.     

Compensation differences between male and female CEOs for publicly traded firms: a nonparametric analysis

A recent article in the popular press suggested that gender is one determining factor of corporate executives' pay. The average compensation for the top 20 men was more than 10 times larger than for the top 20 women. We would expect, however, that direct compensation from salary and bonuses would be similar for both genders given the public nature of the data. There have been few academic articles on the topic of gender pay differences among top executives. One paper found marginally significant statistical evidence that women CEOs are paid more than their male counterparts. In this paper, we extend the literature by looking at compensation differences of male and female CEOs. Our sample includes over 40 female CEOs for publicly traded companies and matched pairs of comparable male CEOs. In addition, we use data envelopment analysis to derive a gap measure representing the difference between male and female compensation. The results suggest that there is a statistical difference between male and female potential compensation.     

Elementary differences between the degrees of unsolvability and degrees of compressibility

Given two infinite binary sequences A,B we say that B can compress at least as well as A if the prefix-free Kolmogorov complexity relative to B of any binary string is at most as much as the prefix-free Kolmogorov complexity relative to A, modulo a constant. This relation, introduced in Nies (2005) [14] and denoted by A≤_LKB, is a measure of relative compressing power of oracles, in the same way that Turing reducibility is a measure of relative information. The equivalence classes induced by ≤_LK are called LK degrees (or degrees of compressibility) and there is a least degree containing the oracles which can only compress as much as a computable oracle, also called the ‘low for K’ sets. A well-known result from Nies (2005) [14] states that these coincide with the K-trivial sets, which are the ones whose initial segments have minimal prefix-free Kolmogorov complexity.We show that with respect to ≤_LK, given any non-trivial sets X,Y there is a computably enumerable set A which is not K-trivial and it is below X,Y. This shows that the local structures of and Turing degrees are not elementarily equivalent to the corresponding local structures in the LK degrees. It also shows that there is no pair of sets computable from the halting problem which forms a minimal pair in the LK degrees; this is sharp in terms of the jump, as it is known that there are sets computable from which form a minimal pair in the LK degrees. We also show that the structure of LK degrees below the LK degree of the halting problem is not elementarily equivalent to the or structures of LK degrees. The proofs introduce a new technique of permitting below a set that is not K-trivial, which is likely to have wider applications.     

Cross-correlations between volatility,volatility persistence and stock market integration: the case of emergent stock markets

In this paper, we investigate the dynamics of the two pairs of relationship, respectively volatility/market integration and volatility persistence/market integration, in the case of 20 emerging stock markets during the period 1999–2013. Employing the rolling windows approach we find that on most markets the persistent positive trend in volatility and volatility persistence is associated with the same trend in market integration. We use the detrending moving-average cross-correlation coefficients and we find positive cross-correlation that appears particularly in the long term and can only partly be attributed to the global financial crisis. The cross-section analysis shows that the markets which are more integrated display stronger volatility and volatility persistence, especially after 2005, when the level of market integration is higher. Our findings have several important implications for international portfolio management and security valuation.     

有效需求与通货紧缩的统计关系研究

本文通过对有效需求一物价指数统计模型的研究 ,估计出了有效需求方程 ,并且通过对模型的估计结果分析得出如下结论 :物价指数对有效需求的影响是显著的 :通货紧缩、物价指数持续走低是有效需求不足的主要原因 ,治理通货紧缩应该是解决我国有效需求不足的主要任务。     

Matricial norms and the differences between the zeros of determinants with polynomial elements

In this paper, we give a method for finding upper bounds for the absolute values of the differences between two latent roots of a lambda-matrix, that is to say, for the differences between two zeros of the determinant of a lambda-matrix. We specialize for complex polynomials.     

The choice of a technical efficiency measure on the free disposal hull reference technology: A comparison using US banking data

This paper evaluates a variety of technical efficiency measures based on a given nonparametric reference technology, the free disposal hull (FDH). Specifically, we consider the radial measure of Debreu (1951)/Farrell (1957) and the nonradial measures of Färe (1975), Färe and Lovell (1978) and Zieschang (1984). Furthermore, input-based, output-based, and graph efficiency versions of these four measures are computed. Theoretical consideration as to the best choice among these alternative measures is inconclusive; therefore, we examine this problem from an empiricalviewpoint. Calculating thirteen different measures of technical efficiency for a sample of US banks, we compare the measures' efficiency distributions and rankings, paying particular attention to how well the radial measure approximates its nonradial alternatives.     

Algorithms for the integration and derivation of Chebyshev series

General formulas for the mth integral and derivative of a Chebyshev polynomial of the first or second kind are presented. The result is expressed as a finite series of the same kind of Chebyshev polynomials. These formulas permit to accelerate the determination of such integrals or derivatives. Besides, it is presented formulas for the mth integral and derivative of finite Chebyshev series and a numerical algorithm for the direct evaluation of the mth derivative of such a series.