bluuebunny/crossref_metadata_2025 huggingface dataset:
A Gravity Model with Variable Coefficients: The EEC Trade with Third Countries
Authors: Zhang Jie , Kristensen Gustav
Published: September 2010

Gravity models with fixed coefficients have been used to explain the trade flows between countries different in income levels and separated by long distances. It is unrealistic to assume that these models can hold with the same parameters across very heterogeneous countries. This paper proposes and estimates an international trade model with variable coefficients constructed by combining Pöy‐hönen's and Linnemann's gravity‐based trade models via the expansion method.
Representing Structural Change in U.S. Migration Patterns
Authors: Rogers Andrei , Wilson Robin Taylor
Published: September 2010

This paper focuses on the identification of three sets of relationships exhibited by a time series of age‐specific national migration rates and multiregional transition probability matrices: the relationship across time for the same age group, as defined by period (temporal) transformation coefficients or matrices; the relationships across age at a particular moment in time, as defined by age transformation coefficients or matrices; and the relationships across time and age, as defined by cohort transformation coefficients or matrices. Given any two of these relationships one can solve for the third. This feature of age‐period‐cohort relationships has a practical application in the development of improved methods for representing structural change in migration patterns over time and for indirectly estimating migration patterns using inadequate data.
Multifractal Characterization of the Distribution Pattern of the Human Population
Authors: Appleby Stephen
Published: September 2010

The generalized entropy, calculated from the quadrat counts of the population of the United States and Great Britain, is plotted against the logarithm of the quadrat size. These graphs are linear over a range of scales that corresponds to the size of a city up to the size of the country. This linearity indicates a strong scale‐invariant component to the spatial population distribution pattern. Measurements of the generalized q‐dimensions and alpha spectrum of the spatial population distribution patterns estimated from these graphs are presented.
Multiagent Systems and the Dynamics of a Settlement System
Authors: Bura Stéphane , Guérin‐Pace France , Mathian Hélène , Pumain Denise , Sanders Lena
Published: September 2010

In order to simulate the evolution of a system of settlements with a dynamic model, many processes must be integrated: the spatial aggregation of population, the complexification of urban activities, and the increasing hierarchical differentiation of settlements. The model must also simulate the progressive structuration of the settlement system through a growing variety and enlarged range of interactions between its elements. “Multiagent systems” provides a flexible modeling method for dealing with the multiple spatial interactions of cooperation and competition and relations that generate and regulate the evolution of a settlement system. Its principles are described and applied to building an evolutionary model, including a simulation tool. The model combines economic and spatial rules to produce birth, growth, decline, and functional diversification of the towns. The “urban transition” from an agrarian settlement system toward a hierarchical system of trade‐ and manufacturing‐oriented towns and cities can be simulated.
A Generalized Model for Cellular Urban Dynamics
Authors: Xie Yichun
Published: September 2010

Cities have long been recognized as complex and dynamic entities. However, the mathematical description of cities has been traditionally based on aggregate observations and on their static properties. Although some new approaches derived from the science of complex systems, particularly Cellular Automata (CA), have been explored in recent years, many urban researchers think that current forms of these models are cursory, fragmentary, and unrealistic in terms of theoretical and practical solidity. This paper generalizes an urban model to deal with questions of dynamic urban evolutionary modeling (DUEM). The DUEM situates its conceptual and technical foundations on Couclelis's CA spaces, Dendrinos' urban selection, and contemporary techniques of GIS. The DUEM provides a generic modeling technique that is capable of capturing the processes of evolutionary reproduction at the finest level and handling interactions between automaton self‐reproduction and environmental and socioeconomic influences through the feedback among neighborhood, field, and region. Here we first review developments of dynamic systems theories and CA in particular. We then discuss emerging issues of CA applications in urban fields, and lay out conceptual foundations for this research. Next, we propose a generic urban CA model—DUEM for describing urban complexities and dynamics. We finally show how this generic model can be used to simulate growth dynamics for multi‐sector land uses in a suburban area of Buffalo, New York.
Spatial Competition and Bounded Rationality: Retailing at the Edge of Chaos
Authors: Krider Robert E. , Weinberg Charles B.
Published: September 2010

The spatial dimension of competition among retail outlets is well researched and typically captured with spatial interaction models. A stream of theoretical research has studied the consequences of incorporating various types of dynamics into these models. We build on this research by incorporating a behavioral decision process based on bounded rationality, and by allowing for unexpected adversity in the environment in the form of exogenous shocks. Given these characteristics—spatial competition, boundedly rational decision making, and environmental adversity—we study the long‐run dynamics of a model retail industry. The model reaches a stochastic steady state which is “poised,” in the sense that a shock may—or may not—trigger a wave of innovation which sweeps the entire system. Detailed investigation of this steady state shows that it has the characteristics of a general type of organization, known as self‐organized criti‐cality, that has been described in both theoretical biology and statistical physics.
Estimating the Size of Social Networks
Authors: Rogerson Peter A.
Published: September 2010

It is notoriously difficult to define and estimate the size of individuals' social networks. Methods are suggested for estimating the size of such networks, using known rates of mobility together with survey data on the number of acquaintances of individuals who have recently moved. Special attention is given to the likely correlation between mobility rates and network size. Estimates are found to be consistent with previous estimates in the literature. The relation of this approach to multiplicity sampling and to “the small‐world problem” is also discussed.
A Selection Bias Approach to Destination Choice
Authors: Miron John R. , Lo Lucia
Published: September 2010

Research on consumer search behavior commonly envisages destination choice as a two‐step process: (1) delineate the search set, and (2) evaluate choices therein. However, much of the empirical work in destination choice—including logit and nested logit formulations—models only the latter, and not the set delineation itself. In the presence of correlation between error terms in set delineation and choice selection, statistical estimators are biased, a problem that Heckman and others have called selection bias. In this paper, an alternative two‐stage method is proposed to estimate the parameters of models of set delineation and choice selection. Monte Carlo simulation is used to explore the properties of these two‐stage estimators, and to show the magnitude of bias inherent in traditional methods of estimation.
Mapping Market Areas Using Nonparametric Smoothing
Authors: Brorsen B. Wade , Von Bailey Dee , Thomsen Michael R.
Published: September 2010

A new method is proposed to map firms' principal market areas using shipment data. The new method is a general one which could prove just as useful in mapping the incidence of disease as in mapping market areas. This method is applied to agricultural data for feeder cattle sales at a video cattle auction. Transportation costs appear to be the main determinant of market area boundaries, but there are many cases where transportation costs alone cannot explain the market areas found. The size and shape of market areas for feeder cattle buyers are large, irregularly shaped, and extensively overlapping.
Quick Computation of Spatial Autoregressive Estimators
Authors: Pace R. Kelley , Barry Ronald
Published: September 2010

Spatial estimators usually require the manipulation of n2 relations among n observations and use operations such as determinants, eigenvalues, and inverses whose operation counts grow at a rate proportional to n3. This paper provides ways to quickly compute estimates when the dependent variable follows a spatial autoregressive process, which by appropriate specification of the independent variables can subsume the case when the errors follow a spatial autoregressive process. Since only nearby observations tend to affect a given observation, most observations have no effect and hence the spatial weight matrix becomes sparse. By exploiting sparsity and rearranging computations, one can compute estimates at low cost. As a demonstration of the efficacy of these techniques, the paper provides a Monte Carlo study whereby 3,107 observation regressions require only 0.1 seconds each when using Matlab on a 200 Mhz Pentium Pro personal computer. In addition, the paper illustrates these techniques by examining voting behavior across U.S. counties in the 1980 presidential election.
Local Spatial Autocorrelation in a Biological Model
Authors: Sokal Robert R. , Oden Neal L. , Thomson Barbara A.
Published: September 2010

We review the recently developed local spatial autocorrelation statistics Ii, ci, Gi, and Gi*. We discuss two alternative randomization assumptions, total and conditional, and then newly derive expectations and variances under conditional randomization for Ii and ci, as well as under total randomization for ci. The four statistics are tested by a biological simulation model from population genetics in which a population lives on a 21 × 21 lattice of stepping stones (sixty‐four individuals per stone) and reproduces and disperses over a number of generations. Some designs model global spatial autocorrelation, others spatially random surfaces. We find that spatially random designs give reliable test results by permutational methods of testing significance. Globally autocorrelated designs do not fit expectations by any of the three tests we employed. Asymptotic methods of testing significance failed consistently, regardless of design. Because most biological data sets are autocorrelated, significance testing for local spatial autocorrelation is problematic. However, the statistics are informative when employed in an exploratory manner. We found that hotspots (positive local autocorrelation) and coldspots (negative local autocorrelation) are successfully distinguished in spatially autocorrelated, biologically plausible data sets.
Transportation Networks and the Location of Human Activities
Authors: Peeters Dominique , Thisse Jacques‐François , Thomas Isabelle
Published: September 2010

The impact of transportation networks on the location of human activities is a surprisingly neglected topic in economic geography. Using the simple plant location problem, this paper investigates such an impact in the case of a few idealized networks. It is seen that a grid network tends to foster a dispersed pattern of activities, while the center of a radial network acts as an attractor. The case of two economies characterized by different network configurations that form a custom union is then analyzed. It is shown that the structural properties of the networks still hold, though some locations are pulled toward the common border. This suggests that no such relocation should be expected within the European Union if the state members endorse similar fiscal and social policies after the formation of the single market.
An Equity Model for Locating Environmentally Hazardous Facilities
Authors: Falit‐Baiamonte Anthony , Osleeb Jeffrey P.
Published: September 2010

This paper develops a multiobjective mathematical location model to identify possible locations for environmentally hazardous facilities. Risk and equity are recognized as the most important criteria in determining site selection. In contrast to earlier models, the equity objective explicitly considers the existing distribution of environmental burdens when siting new hazardous facilities. Proposed environmentally hazardous facilities are located so that the burdens associated with new and existing hazards are shared as equally as possible among all areas. The application of the model, in a case study of the Greenpoint/Williamsburg neighborhood in Brooklyn, New York, illustrates the trade‐offs associated with various risk and equity scenarios. Sensitivity analyses demonstrate how the existing distribution of environmental burdens may act as a constraint and limit the degree of equity that may be obtained when locating new facilities.
Power of the Rank Adjacency Statistic to Detect Spatial Clustering in a Small Number of Regions
Authors: Ekwaru John Paul , Walter Stephen D.
Published: September 2010

The rank adjacency statistic D is a statistical method for assessing spatial autocorrelation or clustering of geographical data. It was originally proposed for summarizing the geographical patterns of cancer data in Scotland (IARC 1985). In this paper, we investigate the power of the rank adjacency statistic to detect spatial clustering when a small number of regions is involved. The investigations were carried out using Monte Carlo simulations, which involved generating patterned/clustered values and computing the power with which the D statistic would detect it. To investigate the effects of region shapes, structure of the regions, and definition of weights, simulations were carried out using two different region shapes, binary and nonhinary weights, and three different lattice structures. The results indicate that in the typical example of considering Canadian total mortality at the electoral district level, the D statistic had adequate power to detect general spatial autocorrelation in twenty‐five or more regions. There was an inverse relationship between power and the level of connectedness of the regions, which depends on the weighting function, shape, and arrangement of the regions. The power of the D statistic was also found to compare favorably with that of Moran's I statistic.
Location‐Specific Cumulative Distribution Function (LSCDF): An Alternative to Spatial Correlation Analysis
Authors: Wong David W.S.
Published: September 2010

Quite often, geographical analysis involves comparing the spatial distributions of two variables or attributes. A typical method is to calculate the correlation coefficient of the two variables for corresponding areal units. Putting aside the fact that correlation coefficient is aspatial in nature (swapping attribute values between spatial units will not alter the value of correlation coefficient) and the issue of spatial dependency (or the potential existence of spatial autocorrelation) among observations, another major problem with using correlation measures for analyzing spatial data is the modifiable areal unit problem (MAUP), especially with the scale effect. Results from correlation analysis vary with the spatial resolutions based upon which spatial data are gathered. This paper presents an approach for spatial correlation analysis for count variables by comparing their cumulative spatial distributions. Using the concept of cumulative distribution function (CDF) in classical statistics, this paper shows that location‐specific CDF (LSCDF) and its associated K‐S‐like statistic, which indicate the magnitude of difference between the two spatial distributions, are highly consistent over different levels of spatial scale. The application of the LSCDF approach is not restricted to isotropic spatial processes and the statistic provides a rather conservative conclusion. In addition, given any origin to construct LSCDFs, the LSCDFs can provide a geographic description of the two spatial distributions. By combining LSCDFs derived from different origins, a comprehensive understanding of the two distributions for the entire study area is developed. This approach for correlation analysis may offer a direction for future investigation of the MAUP.
Dynamic Models in Space and Time
Authors: Elhorst J. Paul
Published: September 2010

This paper presents a first‐order autoregressive distributed lag model in both space and time. It is shown that this model encompasses a wide series of simpler models frequently used in the analysis of space‐time data as well as models that better fit the data and have never been used before. A framework is developed to determine which model is the most likely candidate to study space‐time data. As an application, the relationship between the labor force participation rate and the unemployment rate is estimated using regional data of Germany, France, and the United Kingdom derived from Eurostat, 1983–1993.
Estimating the Variability of Active‐Layer Thaw Depth in Two Physiographic Regions of Northern Alaska
Authors: Gomersall Claire E. , Hinkel Kenneth M.
Published: September 2010

The active layer is the zone above permafrost that experiences seasonal freeze and thaw. Active‐layer thickness varies annually in response to air and surface temperature, and generally decreases poleward. Substantially less is known about thaw variability across small lateral distances in response to topography, parent material, vegetation, and subsurface hydrology.

A graduated steel rod was used to measure the 1998 end‐of‐season thaw depth across several transects. A balanced hierarchical sampling design was used to estimate the contribution to total variance in active‐layer depth at separating distances of 1, 3, 9, 27, and 100 meters. A second sampling scheme was used to examine variation at shorter distances of 0.3 and 0.1 meter. This seven‐stage sample design was applied to two sites in the Arctic Foothills physiographic province, and four sites on the Arctic Coastal Plain province in northern Alaska. The spatial variability for each site was determined using ANOVA and variogram methods to compare intersite and inter‐province variation.

Spatial variation in thaw depth was different in the Foothills and Coastal Plain sites. A greater percentage of the total variance occurs at short lag distances (0–3 meters) at the Foothills sites, presumably reflecting the influence of frost boils and tussock vegetation on ground heat flow. In contrast, thaw variation at the Coastal Plain sites occurs at distances exceeding 10 meters, and is attributed to the influence of well‐developed networks of ice‐wedge polygons and the presence of drained thaw‐lake basins. This information was used to determine an ongoing sampling scheme for each site and to assess the suitability of each method of analysis.
Spatial Empirics for Economic Growth and Convergence
Authors: Rey Sergio J.
Published: September 2010

This paper suggests some new empirical strategies for analyzing the evolution of regional income distributions over time and space. These approaches are based on extensions to the classical Markov transition matrices that allow for a more comprehensive analysis of the geographical dimensions of the transitional dynamics. This is achieved by integrating some recently developed local spatial statistics within a Markov framework. Insights to not only the frequency with which one economy may transition across different classes in the income distribution, but also how those transitions may or may not be spatially dependent are provided by these new measures. A number of indices are suggested as ways to characterize the space‐time dynamics and are illustrated in a case study of U. S. regional income dynamics over the 1929–1994 period.
Classification Analysis of World Economic Regions
Authors: Dezzani Raymond J.
Published: September 2010

Economic classifications of countries are of continuing utility for comparative and analytic purposes. However, traditional methods of arriving at classifications are often ad hoc, subjective, and imprecise, not permitting the assignments to be used for closer analysis. Discriminant analysis is used in this paper to isolate a time‐specific set of economic factors delimiting economic state categories that correspond to core‐periphery states. The core‐periphery framework is shown to be a special case of a hierarchical market scheme. The purposes of this work are (1) to create a theoretically grounded, empirically derived classification over several time periods to permit dynamic comparisons to be made and provide an explanation of change in the global economy, and (2) to provide feedback information from the classification to supply the necessary rigor and quantitative insight to the world‐systems theoretical framework. Results of the analysis suggest that different economic variables provide varying levels of explanation at different times. In particular, variables representing factor endowment provide a greater measure of explanation early in the sequence (for example, 1960) while trade and investment measures are of greater importance in the latter part of the study sequence (for example, 1990). OPEC countries significantly bifurcate the world‐economy classification in 1970 and exhibit separate class characteristics. Even within the short time period, a number of countries are shown to transit among the classes. The model is also able to capture the dependence structure implicit in the world‐systems framework.
Virtual and Traditional Feedback‐Seeking Behaviors: Underlying Competitive Attitudes and Consequent Grade Performance
Authors: Hwang Alvin , Arbaugh J. B.
Published: September 2010

The electronic medium continues to play an increasingly important role in the delivery of management education despite a paucity of empirical studies on its impact and efficacy. Results from a study of competitive attitudes and feedback‐seeking behaviors across seven “hybrid” electronic cum live classes showed that Kiasu‐Negative (a competitive attitude directed at preventing others from getting ahead of oneself) and Kiasu‐Positive (a competitive attitude directed at personal diligence to get ahead of others) (Hwang, Ang, & Francesco, 2002) were related to two electronic discussion board feedback‐seeking behaviors. These feedback‐seeking behaviors, in turn, were related to grade performance as measured by multiple‐choice tests. Traditional feedback‐seeking measures of asking the professor in class or outside the class, and checking with fellow students for their views on class topics did not have a positive influence on multiple‐choice test performance. In light of these findings, educators should consider how best to encourage participation on electronic discussion boards for hybrid type courses, while researchers should further examine the underlying causes of learning from such electronic exchanges. Other implications of these findings are also discussed.
Defining, Assessing, and Promoting E‐Learning Success: An Information Systems Perspective*
Authors: Holsapple Clyde W. , Lee‐Post Anita
Published: September 2010

This research advances the understanding of how to define, evaluate, and promote e‐learning success from an information systems perspective. It introduces the E‐Learning Success Model, which posits that the overall success of an e‐learning initiative depends on the attainment of success at each of the three stages of e‐learning systems development: system design, system delivery, and system outcome. To study this model, an online version of an undergraduate quantitative methods core course for business students is developed using a prototyping strategy. Four cycles of development are traced, each comprised analysis, design, implementation, testing, and enhancement. Findings from the study confirm the validity of using the proposed success model for e‐learning success assessment. In addition, an action research methodology is also found to be a valuable impetus for promoting e‐learning success through an iterative process of diagnosing, action planning, action taking, evaluating, and learning.
Competitive and Cooperative Positioning in Supply Chain Logistics Relationships*
Authors: Klein Richard , Rai Arun , Straub Detmar W.
Published: September 2010

Cooperative logistics relationships require the sharing of information, which must be enabled by the integration of disparate information systems across partners. In this article, we theorize business‐to‐business logistics relationships should be managed using cooperative and competitive postures. Based on data from 91 dyadic relationships using interorganizational information technology (IT), we find that performance gains accrue when parties share strategic information and customize IT; mutual trust enables IT customization and strategic‐information flows and equitable relationship‐specific investments positively impact IT customization, mutual trust, and performance. Among other scholarly and practical implications discussed, partners should compete on resources for IT customization and cooperate to share strategic information. Managers tend to think of relationships with firms as polar opposites and view them as entirely cooperative or entirely competitive. Our results support active balancing and understanding of both competitive and cooperative stances. Such an approach enables conditions for participation symmetry that yields greater performance gains.
Applications of Doppler Echocardiography in Cardiac Pacing
Authors: JANOSIK DENISE L. , PEARSON ANTHONY C. , LABOVITZ ARTHUR J.
Published: September 2010

The purpose of this article is to review the use of Doppler echocardiography for assessing responses during cardiac pacing. Doppler techniques allow the physician to select the optimal mode pacemaker and pacemaker settings with regard to heart rate and atrioventricular delay, at rest and during exercise. Doppler parameters can be used to predict the relative hemodynamic advantage of dual chamber or rate adaptive pacing over fixed rate pacing. This valuable noninvasive modality may enhance the benefit of pacemaker therapy. (ECHOCARDIOGRAPHY, Volume 8, January 1991)
Myocardial Perfusion and Contrast Echocardiography: Review and New Perspectives
Authors: VANDENBERG BYRON F.
Published: September 2010

Myocardial perfusion can be assessed qualitatively and quantitatively with new ultrasound contrast techniques. This article reviews progress and problems in this area, discussing intracoronary and aortic root injections in animals and humans. The technique has great potential clinical application for the identification of coronary flow reserve, and the assessment of the need for and outcome of coronary revascularization procedures. It may allow direct measurements of regional myocardial perfusion. (ECHOCARDIOGRAPHY, Volume 8, January 1991)
Real‐Time, Three‐Dimensional Echocardiography: Feasibility and Initial Us
Authors: SHEIKH KHALID H. , SMITH STEPHEN W. , RAMM OLAF VON , KISSLO JOSEPH
Published: September 2010

The purpose of this article is to review new approaches to three‐dimensional acquisition and presentation ofechocardiographic data. New three‐dimensional phased‐array devices hold great promise for the development and application of new descriptors for left ventricular performance, myocardial perfusion, and other important indices of cardiac function. (ECHOCARDIOGRAPHY, Volume 8, January 1991)
Spider mites (Tetranychus urticae) perform poorly on and disperse from plants exposed to methyl jasmonate
Authors: Rohwer Charles L. , Erwin John E.
Published: September 2010

Jasmonates are plant hormones involved in wound and defense responses against herbivorous arthropods. Methyl jasmonate (MeJA) is used experimentally to induce defense responses in plants. In experiments outlined here we utilized a novel preference assay with unwounded plants that allowed us to study the impact of a MeJA spray on subsequent Tetranychus urticae Koch (Acari: Tetranychidae) proliferation and preference. Spraying plants with 100 μm MeJA 1 day before infestation caused mites to disperse within 2 days from treated impatiens [Impatiens wallerana Hook f., ‘Super Elfin Pink’ (Balsaminaceae)], pansy [Viola × wittrockiana Gams, ‘Imperial Beaconsfield’ (Violaceae)], and tomato [Solanum lycopersicum L., ‘Big Boy’ (Solanaceae)] plants. In addition, MeJA application reduced mite proliferation rate on impatiens and pansy by 60% (measured 22–34 days after infestation). Proteinase inhibitor (PI) assays suggested that MeJA‐induced PIs alone were not responsible for the observed results in pansy and impatiens but may have been a factor in tomato. Implications of these results in the context of MeJA‐induced resistance responses and possible directions for future research and application are discussed.
Immunological, antioxidative, and morphological response in combined treatment of ofloxacin and Lactobacillus fermentum ME‐3 probiotic in Salmonella Typhimurium murine model
Authors: TRUUSALU KAI , KULLISAAR TIIU , HÜTT PIRJE , MAHLAPUU RIINA , AUNAPUU MARINA , AREND ANDRES , ZILMER MIHKEL , MIKELSAAR RAIK‐HIIO , MIKELSAAR MARIKA
Published: September 2010

Truusalu K, Kullisaar T, Hütt P, Mahlapuu R, Aunapuu M, Arend A, Zilmer M, Mikelsaar R‐H, Mikelsaar M. Immunological, antioxidative, and morphological response in combined treatment of ofloxacin and Lactobacillus fermentum ME‐3 probiotic in Salmonella Typhimurium murine model. APMIS 2010; 118: 867–72.

We aimed to elucidate the immunological (cytokines), biochemical (antioxidative), and patho‐morphological responses in the gut and liver evoked by the addition of Lactobacillus fermentum ME‐3 to ofloxacin (OFX) treatment in an experimental infection model of Salmonella enterica serovar Typhimurium. After challenge with S. Typhimurium and treatment according to different schemes, either with OFX and/or addition of L. fermentum ME‐3, the mice were killed. Blood, liver, spleen, and small intestine samples were plated to detect S. Typhimurium and lactobacilli. Histological slides were prepared from the liver and ileum. The cytokines (IL‐10, IFN‐γ, and TNF‐α), the glutathione peroxidase and reductase, the glutathione ratio, and the lipid peroxides (LPO) in mucosa of the small intestine and liver were estimated. The addition of L. fermentum ME‐3 to OFX increased the eradication of S. Typhimurium from tested sites because of antagonistic and antioxidative properties, reduced the presence of typhoid nodules in the liver, and decreased the values of LPO. The immunological response included the reduction of pro‐inflammatory cytokines interferon‐γ and tumour necrosis factor‐α and the increase in anti‐inflammatory cytokine interleukin‐10 in the livers of mice without typhoid nodules.
Effects of multiple competitors for pollination on bumblebee foraging patterns and Mimulus ringens reproductive success
Authors: Flanagan Rebecca J. , Mitchell Randall J. , Karron Jeffrey D.
Published: September 2010

When co‐occurring plant species overlap in flowering phenology they may compete for the service of shared pollinators. Competition for pollination may lower plant reproductive success by reducing the number of pollinator probes or by decreasing the quality of pollen transport to or from a focal species. Pair‐wise interactions between plants sharing pollinators have been well documented. However, relatively few studies have examined interactions for pollination among three or more plant species, and little is known about how the outcomes and mechanisms of competition for pollination may vary with competitor species composition. To better understand how the dynamics of competition for pollination may be influenced by changes in the number of competitors, we manipulated the presence of two competitors, Lythrum salicaria and Lobelia siphilitica, and quantified reproductive success for a third species, Mimulus ringens. Patterns of pollinator preference and interspecific transitions in mixed‐species arrays were significantly influenced by the species composition of competitor plants present. Both pair‐wise and three‐species competition treatments led to a similar ∼ 40% reduction in Mimulus ringens seed set. However, the patterns of pollinator foraging we observed suggest that the relative importance of different mechanisms of competition for pollination may vary with the identity and number of competitors present. This variation in mechanisms of competition for pollination may be especially important in diverse plant communities where many species interact through shared pollinators.
Crystal growth by restorative filling materials
Authors: Endo Kazuhiko , Hashimoto Masanori , Haraguchi Katsuhiro , Ohno Hiroki
Published: September 2010

Endo K, Hashimoto M, Haraguchi K, Ohno H. Crystal growth by restorative filling materials. Eur J Oral Sci 2010; 118: 489–493. © 2010 Eur J Oral Sci

This study examined the activity and ability of materials to mineralize teeth in gaps, simulating microleakage between the materials and teeth. Three restorative materials (two glass ionomer cements and a compomer) were used in this study. Cured disks of restoratives were placed over flat human tooth surfaces (enamel and dentin), separated by a standardized 20‐μm interfacial space, and stored in water for 24 h or 1 yr. After the water‐storage period, the materials were detached from the teeth and the opposing surfaces were examined by scanning electron microscopy (SEM) and electron probe micro analysis (EPMA).Hemispherical‐shaped precipitations, composed of minute semicircle plate‐like crystals, were observed by SEM on the enamel surface after 1 yr of water storage for glass ionomer cement. The amount of crystal growth with the chemical‐cured type of glass ionomer cement was greater than with the dual‐cured type of glass ionomer cement. However, there was no crystal formation in the compomer. Moreover, no structural changes were observed on dentin surfaces for any material in water after 1 yr. The elements detected in the crystals by EPMA were calcium (Ca), phosphorus (P), and aluminum (Al). The two glass ionomer cements tested have the ability to induce crystals whose composition might be derived from cured glass ionomers.
The long-term impact of bereavement upon spouse health: a 10-year follow-up
Authors: Jones Michael P. , Bartrop Roger W. , Forcier Lina , Penny Ronald
Published: September 2010

Jones MP, Bartrop RW, Forcier L, Penny R. The long-term impact of bereavement upon spouse health: a 10-year follow-up.

Objectives:

This study is the first to examine the effect of bereavement of a first-degree family member on subsequent morbidity over a 10-year follow-up period.

Methods:

A sample of bereaved subjects (n = 72) were compared with a control group (n = 80) recruited in the same period with respect to morbidity experience during follow-up. Morbidity events were ascertained from the subject themselves, their health care providers and these sources were also compared.

Results:

Bereavement was associated with an elevated total burden of illness as well as with mental health and circulatory system categories diagnosed according to the International Classification of Diseases - Clinically Modified (ICD-9) classification system. The elevation ranged from approximately 20% for any illness to 60–100% among circulatory system disorders. Although in an earlier study there was a downregulation of T-cell function in the bereaved during the first 8 weeks, there was no evidence that the bereavement was associated with increased morbidity in the respiratory or immune system ICD-9 categories long-term.

Conclusions:

Past epidemiological research has indicated that bereavement of a close family member is associated with adverse health consequences of a generalised morbidity. Our study suggests an increase in mental health and circulatory system effects in particular. Further research is required to determine whether other systems are also affected by bereavement.
Functional polymorphism of the myeloperoxidase gene (G-463A) in depressive patients
Authors: Gałecki Piotr , Florkowski Antoni , Bobińska Kinga , Śmigielski Janusz , Bieńkiewicz Małgorzata , Szemraj Janusz
Published: September 2010

Gałecki P, Florkowski A, Bobińska K, Śmigielski J, Bieńkiewicz M, Szemraj J. Functional polymorphism of the myeloperoxidase gene (G-463A) in depressive patients.

Objective:

Myeloperoxidase (MPO) is an enzyme involved in the production of hypochloric acid as well as other reactive oxygen species. This enzyme plays a significant role in inflammatory processes. In view of the observed associations between depression and such inflammatory processes, as well as of the reports that confirm the presence of oxidative stress in depression, this study was designed to assess the correlation, if any, between the single nucleotide polymorphism G-463A of the MPO gene and the risk of recurrent depressive disorders (DD).

Methods:

The study was carried out in a group of 149 patients with recurrent DD and 149 healthy control subjects. Genotyping was performed by PCR/restriction fragment length polymorphism.

Results:

A comparison between healthy controls and depressive patients showed a statistically significant difference in genotype distribution and allele frequency in the studied groups. Genotype distribution and allele frequency did not correlate with clinical variables of the patients.

Conclusion:

The obtained results of the study allow us to draw a cautious conclusion about the role of the analysed G-463A MPO polymorphism in recurrent DD development, which, however, requires eventual confirmation in further studies.
Bed‐sharing among six‐month‐old infants in western Sweden
Authors: Möllborg P , Wennergren G , Norvenius SG , Alm B
Published: September 2010

Aim:  In spite of several reports of an increased risk of sudden infant death syndrome (SIDS) in connection with bed‐sharing, it is not an uncommon practice. The aim of this study was to examine bed‐sharing at 6 months of age and the factors that are associated with bed‐sharing.

Methods:  Our cohort comprised 8176 randomly chosen families. At 6 month of age, the families received an invitation to the study, with a questionnaire, which was completed by 5605 families (response rate 68.5%).

Results:  Of the families, 19.8% bed‐shared. In the multivariate analysis, we found a correlation between breast‐feeding and bed‐sharing (breast‐feeding at 6 months: OR 1.94; 95% CI 1.56, 2.41). Moreover, we found an association with 3+ nightly awakenings at 6 months (2.70; 2.20, 3.32). It was more common to share a bed if the parent was single (2.04; 1.19, 3.51) and less common if the infant was bottle‐fed in the first week (0.70; 0.54, 0.90). Never using a pacifier was associated with a higher frequency of bed‐sharing.

Conclusion:  We found a correlation between breast‐feeding and bed‐sharing as well as between sleeping problems and a single parent. A lower percentage of infants sleeping in the parental bed were seen in association with formula feeding in the first week after birth.
Lamellar body counts on gastric aspirates for prediction of respiratory distress syndrome
Authors: Verder H , Ebbesen F , Brandt J , Dahl M , Esberg G , Eschen C , Grytter C , Kroner J , Nørgaard M , Reinholdt J , Stanchev H ,   for the Danish‐Swedish Multicenter Study Group for Surfactant Replacement
Published: September 2010

Aim:  To develop a rapid method for diagnosing lung maturity at birth with the purpose of administering surfactant early to infants with immature lungs and to spare infants with mature lungs from this treatment.

Methods:  Lamellar body counts (LBC) on gastric aspirates from 191 newborns were counted in the platelet window in automatic blood cell counters. A preliminary study was performed on 108 aspirates from 2000 in infants with <32 weeks’ gestation. Furthermore, 83 aspirates from 2004 to 2005 in infants with <30 weeks’ gestation were analysed.

Results:  Lamellar bodies in gastric aspirate were identified by electron microscopy. Seventy of the aspirates from 2004 to 2005 were analysed with a Sysmex XE‐2100 (Sysmex, Holbæk, Næstved, Odense and Rigshospitalet, Denmark) counter. Twenty‐four of these infants developed moderate to severe respiratory distress syndrome (RDS). The best cut‐off value was 8000/μL with a sensitivity of 75% and a specificity of 72%. Forty‐four of the 70 aspirates from 2004 to 2005 were analysed by Sysmex, Advia 120 and Cell‐Dyn 4000. Thirteen other aspirates from 2004 to 05 were analysed by Sysmex and Coulter Counter LH755. Using Advia and Coulter the results were similar to Sysmex, but LBC obtained with Cell‐Dyn were not correlated with the development of RDS.

Conclusion:  Lamellar body counts on gastric aspirate is a promising tool for prediction of development of RDS in infants of <30 weeks` gestation.
EITC Participation and Association With Financial Distress Among Rural Low‐Income Families
Authors: Gudmunson Clinton G. , Son Seohee , Lee Jaerim , Bauer Jean W.
Published: September 2010

This study examined Earned Income Tax Credit (EITC) participation among rural, low‐income families, by income level, and investigated whether nonparticipation corresponds with increased financial distress. Rates of EITC participation among 314 rural low‐income mothers were lower than national averages, especially among the lowest earners. There was, however, an increase from one year to the next, perhaps because of study involvement. Eligible families that did not participate in the EITC experienced greater income inadequacy and economic loss. Professionals who work with families in rural areas may increase EITC participation through outreach to the lowest earning families by emphasizing the need to file tax returns, discussing the potential size of the benefit, and helping families gain access to free tax preparation services.
Adapting to Hard Times: Family Participation Patterns in Local Thrift Economies
Authors: James Spencer , Brown Ralph B. , Goodsell Todd L. , Stovall Josh , Flaherty Jeremy
Published: September 2010

Using survey data from a western U.S. county (N = 595), we examined how lower, middle, and higher income families negotiate a period of economic stress—the closing of a major employer in the community—through their shopping patterns. Specifically, we examined their participation in local thrift economies such as yard sales and secondhand stores. We found that lower and middle income households shop more frequently at these venues. They also tend to shop more for furniture and clothing, whereas higher income households tend to shop for antiques and trinkets. These relationships varied across the type of thrift economy examined. Overall, findings support the argument that engagement in thrift economies may constitute one mechanism families use during periods of economic stress.
Female Anxiety and Male Depression: Links Between Economic Strain and Psychological Aggression in Argentinean Couples
Authors: Falconier Mariana K.
Published: September 2010

A dyadic model of economic strain was applied to the study of anxiety and depression as mediating mechanisms in the economic strain‐psychological aggression relation. Data came from self‐report questionnaires completed by 143 Argentinean clinical couples. Structural equation modeling analysis indicated that anxiety and depression increased for both partners when they were experiencing economic strain, but only the female anxiety and the male depression increased both partners' psychological aggression. These findings and their implications for researchers, clinicians, and program designers are discussed.
Challenging Behaviours in Dementia: a Project at Hornsby/Ku‐Ring‐Gai Hospital
Authors: Bird Mike , Llewellyn‐Jones Robert , Smithers Heather , Andrews Carol , Cameron Ian , Cottee Angus , Hutson Cathie , Jenneke Bill , Kurrle Susan , Russell Bob
Published: September 2010

Abstract: This paper introduces a two year study at Hornsby/Ku‐Ring‐Gai Hospital which aims to shed more light on the nature of behaviour problems in dementia, and on methods of dealing with them. Rather than trialing a standard therapeutic technique across a range of behaviours, the project attempts to reflect what is often a complex clinical situation not amenable to standard answers. A series of interventions is being instituted in a controlled trial on the assumption that each case is idiosyncratic both in aetiology and other variables which affect treatment choice. Data are collected on quantitative and qualitative aspects of each case, including presumed causes of the behaviour. Outcome is assessed two and five months after the intervention using measures of patient behaviour, and of carer distress, coping and perception of the problem.
The Prevalence of Childlessness in Cohorts of Older Women
Authors: Rowland D. T.
Published: September 2010

Book reviews in this article:

Objective: To define the immediate causes of childlessness and provide estimates of the percentages of women ‐ in the past and present aged population of Australia ‐ who remained voluntarily or involuntarily childless.

Method: The overall prevalence of childlessness in Australian cohorts born since 1851 is estimated as the sum of the effects of never marrying, remaining childless within marriage, and child mortality.

Data: The principal data sources were census statistics for various years on marital status and number of children ever born to women. The paper measures childlessness when each birth cohort was aged 45–49; the proportions are expected to be similar at ages 65–69.

Results: The proportion of women childless has ranged between 9 and 32 per cent in cohorts born since the 1850s. Married childlessness was predominant among cohorts born between the 1890s and the 1920s, owing to the effects on family building of the two World Wars and the Great Depression.

Conclusion: In 1996, cohorts with relatively high levels of childlessness were at advanced ages. Trends in childlessness draw attention to deficits in the family resources of the aged and raise questions about the adequacy of support for vulnerable groups.
Factors Associated with Successful Ageing
Authors: Jorm Anthony F. , Christensen Helen , Henderson A. Scott , Jacomb Patricia A. , Korten Ailsa E. , Mackinnon Andrew
Published: September 2010

Book reviews in this article:

Objective: To assess the prevalence of successful ageing and the factors associated with it.

Method: An epidemiological survey was carried out with 1,045 persons aged 70+ living in Canberra or Queanbeyan. Successful ageing was defined as living in the community without disability, with excellent or good self‐rated health and a high score on a cognitive screening test.

Results: The prevalence of successful ageing declined steeply from age 70–74 to age 80+. Men had a higher prevalence than women. In both men and women, successful ageing was associated with higher verbal intelligence. For women there were, in addition, associations with lower neuroticism, not smoking and lower frequency of strenuous activity earlier in life.

Conclusions: While the ageing of the population may lead to a higher prevalence of age‐related disease, increasing intelligence test scores in future cohorts of the elderly may lead to countervailing positive effects on successful ageing.
Computers: a Learning System that Increases Interest and Confidence
Authors: Buys Laurie R.
Published: September 2010

Book reviews in this article:

Objective: To investigate the impact of an individualised computer learning system designed for older adults living in residential care.

Method: A survey method was used to interview 13 people living in two hostels.

Results: The participants increased their interest and confidence in using the computer through weekly participation in the program. Most participants indicated that the individualised learning and hands‐on experience were most helpful in developing their new skills. Physical disabilities and illness did not appear to significantly impact on the amount of computer usage.

Conclusions: The conclusions suggest that the findings have relevance for program development.