COMPUTATIONAL COMPARISONS OF SPATIAL PRICE EQUILIBRIUM METHODS*

ABSTRACT. In this paper we propose new algorithms for the solution of both general and standard spatial price equilibrium problems, and test their performance with existing algorithms on randomly generated problems. For the standard problem, we propose decomposition schemes based on the concept of “equilibration operator” and compare their performance with the Frank-Wolfe method. For the general problem, we present alternative variational inequality formulations defined over Cartesian products of sets and then exploit these formulations to construct Gauss-Seidel-type serial decomposition methods. We then compare their performance with the projection method. Our computational tests suggest that the new schemes are substantially more efficient than earlier ones.     

The Ryan White Act in Dallas

Virtually every locality affected by the AIDS epidemic has had to confront changes in the demographics of the disease, shifts in federal priorities, and medical advances in AIDS treatment. Creating a consistent federal policy has proven difficult because the epidemic manifests itself differently in virtually every locality it invades. As a result, some local caseloads increasingly are dominated by intravenous drug users and others by gay men. In recognition of this reality, the primary federal program to fund AIDS services relies on local decisionmakers to make allocation decisions for serving the needs of their caseload. Under the Ryan White Comprehensive AIDS Resources Emergency (CARE) Act of 1990, local Health Services Planning Councils were assigned the task of creating an effective continuum of care for persons with HIV I AIDS and were empowered with the task of allocating federal funds to accomplish that objective. In some cases creating and fostering an effective continuum of care proved to be an essentially noncontroversial managerial task, while in other localities political turmoil and rampant self-interest served as barriers to program effectiveness. This article explores the relationship between local political culture and the development of AIDS programs in Dallas County, Texas. Specifically, we compare the provision of AIDS services in Dallas before passage of the Ryan White Act in 1990, how these services were affected by the Ryan White program, and the experiences since the reauthorization of the Ryan White Act in 1996.     

Collective Action Problem Characteristics and Partner Uncertainty as Drivers of Social Tie Formation in Collaborative Networks

The effectiveness of collaboration is often explained by the alignment of social networks with collective-action problem characteristics, yet previous research on social tie formation has focused almost exclusively on actor and relational attributes. We theorize that collective-action problem characteristics together with actor and relational attributes explain social tie formation and that the relative effect of these factors varies with uncertainty about collaboration partners. The study tests seven hypotheses associated with these factors by estimating multilevel network models of collaboration and task engagement among managers responding to a major wildfire in Sweden. The combination of actors and tasks in a single model captured key characteristics of the collective action problem (task engagements and task interdependencies), and disentangled the relative effects of these factors from actor and relational attributes. Results suggest that social tie formation can be explained both by actors’ task engagements, and actor attributes associated with leadership, professionalization, and experience. Further, the effect of task engagements decreases in organizational relationships where collaborative uncertainty is high. Since the alignment of social ties with problem characteristics is supposedly positively associated with collaborative effectiveness, this finding suggests that risk-aversion is a more deep-rooted driver of tie formation than the pursuit of collective performance.     

RESEARCH AND DEVELOPMENT OF ARMS

Military R&D is an important element in our national security, although advanced technology by itself does not insure military superiority. There is a large well-funded program for military R&D in the U.S. Two kinds of questions are raised in connection with this program: the problem of optimizing the military effectiveness of the program through the allocation of resources among R&D projects and between R&D and other elements in the defense budget; and the problem of the long-range effects of new weapons technology on international stability.     

Parameterization and Visualization of the Errors in Areal Interpolation

Areal interpolation involves the transfer of data from one zonation of a region to another, where the two zonations of space are geographically incompatible. By its very nature this process is fraught with errors. However, only recently have there been specific attempts to quantify these errors. Fisher and Langford (1995) employed Monte Carlo simulation methods, based on modifiable areal units, to compare the errors resulting from selected areal interpolation techniques. This paper builds on their work by parameterizing and visualizing the errors resulting from the areal weighting and dasymetric methods of areal interpolation. It provides the basis for further research by developing the methodology to produce predictive models of the errors in areal interpolation. Random aggregation techniques are employed to generate multiple sets of source zones and interpolation takes place from these units onto a fixed set of randomly generated target zones. Analysis takes place at the polygon, or target zone level, which enables detailed analysis of the error distributions, basic visualization of the spatial nature of the errors and predictive modeling of the errors based on parameters of the target zones. Correlation and regression analysis revealed that errors from the areal weighting technique were related to the geometric parameters of the target zones. The dasymetric errors, however, demonstrated more association with the population or attribute characteristics of the zones. The perimeter, total population, and population density of the target zones were shown to be the strongest predictive parameters.     

Handling Large Numbers of Attributes and/or Levels in Conjoint Experiments

Conjoint models have become an established modeling tool for geographical studies. At the core of conjoint models is experimental design, which combines attributes into profiles according to statistical principles. Orthogonal design is the widely used method of experimental design. This method, however, has the problem that task sizes rapidly increase with increasing numbers of attributes and/or levels. Efforts have been spent to overcome this problem, but all existing proposals are based on orthogonal design, providing no radical solution to the problem. In this paper, we attempt to deal with the problem using a new experimental design method that has recently attracted the attention of international statisticians—uniform design, a method that can easily deal with large numbers of attributes and/or levels. The basic idea of this method is to select experimental points (or profiles) that are uniformly scattered in the problem domain, based on the theorem that uniformly distributed experimental points will ensure that the estimated model has the minimum gap with the true model. The key of uniform design is therefore to select designs that have maximum uniformity, which indicates to what extent the experimental points provided by a design are uniformly distributed. The new method is illustrated and tested by a case of intercity transport mode choice.     

Development of Collaborative Structure Analysis (CSA) System and Its Application to Investigate Effects of Soil-Structure Interaction

In this article, a collaborative structure analysis (CSA) system is developed for integrating different finite-element simulation programs. In this system, a simulated structure is divided into multiple substructures, and the interaction between the substructures is considered. Interfaces for the commercial finite-element program ABAQUS and for an open-source framework for structure analysis, OpenSees, are developed to achieve CSA integration. The CSA system is applied to analysis of a soil-structure interaction (SSI) problem, and the effects of SSI are investigated, and the efficiency and accuracy of the system are demonstrated.     

Programming Models for Facility Dispersion: The p-Dispersion and Maxisum Dispersion Problems

The p-dispersion problem is to locate p facilities on a network so that the minimum separation distance between any pair of open facilities is maximized. This problem is applicable to facilities that pose a threat to each other and to systems of retail or service franchises. In both of these applications, facilities should be as far away from the closest other facility as possible. A mixed-integer program is formulated that relies on reversing the value of the 0–1 location variables in the distance constraints so that only the distance between pairs of open facilities constrain the maximization. A related problem, the maxisum dispersion problem, which aims to maximize the average separation distance between open facilities, is also formulated and solved. Computational results for both models for locating 5 and 10 facilities on a network of 25 nodes are presented, along with a multicriteria approach combining the dispersion and maxisum problems. The p -dispersion problem has a weak duality relationship with the (p-1)-center problem in that one-half the maximin distance in the p-dispersion problem is a lower bound for the minimax distance in the center problem for (p-1) facilities. Since the p-center problem is often solved via a series of set-covering problems, the p-dispersion problem may prove useful for finding a starting distance for the series of covering problems.     

Fluid dynamics and fluid‐structural relationships in the Red Lake mine trend,Red Lake greenstone belt,Ontario, Canada

The Red Lake mine trend, a deformation zone in the Archean Red Lake greenstone belt that hosts the world‐class Campbell‐Red Lake gold deposit, is characterized by abundant foliation‐parallel iron‐carbonate ± quartz veins with banded colloform‐crustiform structures and cockade breccias overprinted by silicification and gold mineralization. There is an apparent incompatibility between the cavity‐fill structures of the veins and breccias (typically developed at shallow crustal depths) and the upper greenschist to lower amphibole facies metamorphic conditions recorded in the host rocks (indicating relatively deep environments). This, together with the development of veins along the foliation plane, represents an enigmatic problem that may be related to the interplay between fluid dynamics and stress field. We approach this problem through systematic study of fluid inclusion planes (FIPs) in the vein minerals, including the orientations of the FIPs and the pressure–temperature conditions inferred from fluid inclusion microthermometry. We find that fluid inclusions in the main stage vein minerals (pregold mineralization ankerite and quartz and syn‐ore quartz) are predominantly carbonic without a visible aqueous phase, whereas many inclusions in the postore stage contain an aqueous phase. Most FIPs are subvertical, and many are subparallel to the foliation. High fluid pressure coupled with the high wetting angles of the water‐poor, carbonic fluids may have been responsible for the abundance of brittle deformation features. The development of subvertical FIPs is interpreted to indicate episodic switching of the maximum principal compressive stress (σ₁) from subhorizontal (perpendicular to the foliation) to subvertical (parallel to the foliation) orientation. The subvertical σ₁ is favorable for the formation of foliation‐parallel veins, as fractures are preferentially opened along the foliation in such a stress regime, the origin of which may be linked to the fluid source.     

Fifty Volumes of the Serial Voprosy Geografii

Professor Saushkin, a member of the editorial board of Voprosy Geografii since its inception, reviews the first 50 volumes of the serial and its program of publication. Many volumes of Voprosy Geografii have contained inter-disciplinary articles focused on specific geographic problems. This integrated approach to geography has often aroused controversy. Seven major fields of research of Soviet geography are outlined for the period 1960–80.     

THE MAXIMUM CAPTURE OR “SPHERE OF INFLUENCE” LOCATION PROBLEM: HOTELLING REVISITED ON A NETWORK*

ABSTRACT. The problem of the ice cream vendor on the beach is extended to the siting of multiple entering servers into the midst of existing servers which are already in place at multiple sites on a network. The network of population nodes, joining arcs, and eligible sites for servers provides the underlying matrix of the problem. The goal of the single firm which is siting the multiple entering servers is the capture of the maximum population from existing servers. This combinatorial problem can be described as a linear integer program for which solutions can easily be derived. Computational experience and insights derived therefrom are reported.     

Effects of U.S. States' Social Welfare Systems on Population Health

Social scientists have studied the welfare state extensively. Many studies seek to understand the determinants of the welfare state; however, a few have explored the social consequences of social welfare systems, especially on health outcomes of the population. Even though cross-national comparative studies support the thesis that the welfare state regime type, which represents different levels of commitment on social welfare, is closely linked to population health, there is little research to support this argument at a sub-national level. To fill the gap, this study explores the effects of the U.S. states' social welfare systems on health using age-adjusted mortality rates as a proxy for population health. By operationalizing social welfare systems as three dimensions—public expenditures, tax structures, and welfare program rules—we find that more generous education spending, progressive tax systems, and more lenient welfare program rules help to improve population health. The model corrects for first-order serial correlation using Prais-Winsten regression methods and is estimated with state and year-fixed effects.     

FUZZY PATTERN CLASSIFICATION OF STRONG GROUND MOTION RECORDS

Classification of earthquake strong ground motion (SGM) records is performed using fuzzy pattern recognition to exploit knowledge in the data that is utilised in a genetic algorithm (GA) search and scaling program. SGM records are historically treated as “fingerprints” of certain event magnitude and mechanism of faulting systems recorded at different distances on different soil types. Therefore, databases of SGM records of today present data of complex nature in high dimensions (many of the dimensions—or SGM parameters in time and frequency domain—are presently available from different archives). In this study, simple ground motion parameters were used but were combined and scaled nonlinearly such that the physical properties of the data could be preserved while reducing its dimensionality. The processed data was then analysed using fuzzy c-means (FCM) clustering method to explore the possibility of meaningfully representing earthquake SGM data in lower dimensions through finding subsets of mathematically similar vectors in a benchmark database. This representation can be used in practical applications and has a direct influence on the processes of synthesising ground motion records, identifying unknown ground motion parameters (e.g. soil type in this study), improving the quality of matching SGM records to design target spectra, and in rule generalisation for response. The results showed that the stochastic behaviour of earthquake ground motion records can be accurately simplified by having only a few of motion parameters. The very same parameters may also be utilised to derive unknown characteristics of the motion when the classification task on “training” records is performed carefully. The clusters are valid and stable in time and frequency domain and are meaningful even with respect to seismological features that were not included in the classification task.     

微电脑古汉字操作系统的设计

本文着重介绍了微电脑古汉字操作系统(AC-DOS)的设计思想和主要技术.古汉字操作系统按隶定古汉字的对应楷体字来取字形四角码作为古汉字输入编码.在机内码设计中,为了保证古汉字操作系统 AC-DOS 与广泛使用的 CC-BIOS 之间的向上兼容性,本系统就利用GB-2312-80信息交换用汉字编码字符基本集中,从81h 到A0h 之间的一大片被搁置了的空间作为古汉字的机内码区.因为古汉字的字形需要24×24的点阵结构,存储容量相当大。本系统是采用分级动态调入和内存局部覆盖相结合的技术来解决内存容量的不足.古汉字的输出是在图象输出工作方式下进行的。系统舍去原有的 ASCII 字符发生器,采用了重编西文字符的字形点阵,修正现代楷体汉字显示范围的方法.保证了西文字符与楷体汉字,古汉字在字形尺寸上的比例关系与机内码的比例一致.此外,在显示和打印处理模块中增加了行尾处理功能.本设计参考 CC-BIOS 的汉化方法,通过修改中断入口地址的方式,修改扩充了 ROM-BIOS 的自举程序模块和键盘管理模块、CRT 显示控制模块、打印机驱动模块等四部分.同样,利用系统的自动批处理功能来实现古汉字操作系统 AC-DOS 的自举.     

Comparison of the Spectral Representation Method to Simulate Spatially Variable Ground Motions

The spectral representation method (SRM) is widely used when simulating spatially variable ground motions. It has mainly two formulas, i.e., the random amplitudes and the random phases formulas. There exist three methods for decomposing the cross spectral density matrix: Cholesky decomposition, eigen decomposition, and root decomposition. Therefore, there are six forms with respect to the different combinations of the simulation formulas and the decomposition methods. To provide researchers and engineers with the guidance on choosing simulation method, the six forms are systematically investigated from five aspects: the power intensity, response spectra, and stochastic error of auto/cross spectral density, Fourier spectra, and difference indexes for Fourier amplitudes and phases. Finally, we give the following advice: the characteristics of the ground motions simulated by the random amplitudes formula are independent of the decomposition method, while the characteristics of the ground motions simulated by random phases formula are dependent of the decomposition method. Furthermore, the root decomposition is strongly recommended when utilizing the random phases formula.     

Interpolating geochemical patterning of activity zones at Late Neolithic and Early Copper Age settlements in eastern Hungary

The Late Neolithic of southeast Hungary is known almost exclusively from excavations of large settlement mounds, or tells. Geochemical analyses of sediments collected from boreholes at small, flat Late Neolithic and Early Copper Age settlements in Hungary's Körös River basin provide data necessary to interpret the spatial organization of small settlements for the first time in this region. Principal Components Analysis of multi-element data produced a workable number of variables. Spatial analyses of these components via interpolation in ArcGIS 9 identified specific task areas, and when combined with sediment characterizations, phosphate ‘spot-tests’ and pH, suggest long-term cultural traditions in the location of activity zones within small farmsteads. The results demonstrate the usefulness of multi-element geochemistry as an intra-site prospection method.     

Accuracy of Count Data Estimated by the Point‐in‐Polygon Method

This paper analyzes the accuracy of count data estimated by the point‐in‐polygon method. A point‐in‐polygon interpolation model is proposed, based on a stochastic distribution of points and the target zone, in order to represent a variety of situations. The accuracy of estimates is numerically investigated in relation to the size of the target zone and the distribution of points, and the optimal location of representative points is discussed. The major findings of this paper are as follows: (1) though the relative accuracy of estimates generally increases monotonously with the size of the target zone, the monotoneity is often disturbed by the periodicity in the spatial configuration of source zones and the point distribution; (2) the point‐in‐polygon and the areal weighting interpolation methods have the same accuracy of estimates when points are concentrated in less than 12–15 percent area around the representative point in source zones; (3) the point‐in‐polygon method is not so robust against the locational gap between points and the representative point; (4) the optimal location of representative points is given by the spatial median of points.     

BERNARD GROETHUYSEN's WAY OF COPING WITH THE “PROBLEM OF HISTORICISM”

This article argues that Groethuysen's creation of a new historiographical genre—the anonymous history of the formation of worldviews—was a response to the “problem of historicism” conceived of as a task of working out a concept of historicity beyond the relativism–objectivism dilemma. In scrutinizing Groethuysen's implementation of phenomenology to study how basic historical phenomena have been experienced, the article draws a parallel with Heidegger's response to historical relativism. In the main argument, Groethuysen's combination of a new approach to the history of ideas and a historicized philosophical anthropology reveals the possibility of avoiding the depressing dilemma between metahistorical objectivism and historicist relativism by means of a double hermeneutics. In this regard, special attention is paid to Groethuysen's phenomenological conception of narrative time.