bluuebunny/crossref_metadata_2025 huggingface dataset:
Mismatch in the West German Labour Market? Economic Restructuring and Unemployment in the 1980s*
Authors: Schettkat Ronald
Published: June 2007

Abstract. The paper briefly investigates theoretical arguments for mismatch unemployment; it presents a vacancy‐unemployment curve for Germany and investigates various reasons for outward shifts of the curve. Both variables, unemployment and vacancies, are decomposed into flows and duration to identify the underlying processes of these shifts. The analysis of the components with the help of change‐duration curves shows adverse trends for unemployment and vacancies over the business cycles. Unemployment duration has increased while vacancy duration has decreased. Mismatch in the labour market can therefore hardly be blamed to have been an obstacle for economic expansion in the German economy during the 1980s. Persistently high unemployment in Germany has to be interpreted as a hysteresis process which was driven by macroeconomic policies, increasing labour supply and restructuring imbedded in the German institutional framework.
Raising Children: Private Expenditure and Foregone Earnings*
Authors: Buchegger Reiner , Zweimuller Josef
Published: June 2007

Abstract. From the point of view of an individual household there are two major types of private cost of children, viz. direct household expenditure for the offspring plus (usually) mothers' foregone earnings. Both aspects have been studied theoretically and empirically, but thus far only separately. The joint empirical analysis of these main costs of children are the subject of this paper. Employing the Austrian Consumer Survey of 1984/85 and 1983's Microcensus, household expenditure on one, two and three children and mothers' foregone earnings are estimated for a comparable sample of households.

In order to estimate household expenditure on children a modified Prais‐Houthakker model has been employed. Labour force participation functions as well as human‐capital wage equations were estimated using a multinomial logit model and allowing for both the impact of career interruptions and part‐time work. Through simulation on the basis of these estimates we arrive at comparable life‐time earnings of women with no, one, two or three children. We then add the relevant differences to the expenditure on children to obtain the “total” private cost of children.

Being aware of the limitations of our analysis–not all monetary private outlays and no public expenditure are included, no consideration of children's benefits to parents, etc. ‐ we can nevertheless draw some tentative conclusions: there are decreasing marginal costs for the second child and rather constant costs for the third child, except for the case of “low attachment“ to the labour force, where marginal cost also declines for the third child. Assuming utility maximizing households, one could arrive at a policy prescription for raising birth rates: find a means to reduce foregone earnings which appear to be a major deterrent to having more than one child.
Wage Structure, Incomes Policy and Decentralised Bargaining: the Case of Greece
Authors: Ioannou Christos
Published: June 2007

Abstract. Developments in Greek industrial relations suggest that decentralised bargaining is not a panacea. The manufacturing wage structure in Greece has an exceptional course associated with the rise of informal decentralised bargaining. Interindustry wage differentials increased in a period of incomes policies aiming to narrow the wage structure. The influence exerted by inflation and unemployment is, compared to past evidence from the US. and the U.K., quite unconventional. Under informal bargaining, high‐wage powerful industrial branches “benefit” from higher inflation and lower unemployment.
Supply Policies in an Open Economy with Centralized Wage Setting
Authors: Quintieri Beniamino , Rosati Furio Camillo
Published: June 2007

Abstract. In this paper we examine the effectiveness of a fiscal policy based on government subsidies to firms in an open economy, characterized by the “strategic” interaction of government and unions. Before developing the theoretical model, some evidence about government reaction functions for selected OECD countries is presented. The main theoretical results can be summed up as follows. A fiscal policy based on a tax‐financed increase in government transfers to firms makes the country more competitive internationally, but reduces employment. Only when the increase in government transfers to firms is financed by the public debt is the fiscal policy able to achieve its two‐fold aim of greater competitiveness and a higher level of employment.
Trade Union Action and Privatisation in Western Europe: Recent Dilemmas*
Authors: Casale Giuseppe
Published: June 2007

Abstract. The Author examines the policies of privatisation in Western Europe and the responses made by trade unions. Privatisation seems to induce the trade union movement to shift its emphasis from traditional issues toward new and challenging ones, such as a major co‐operation in the management of the privatised companies. Therein, the extension of interest and control by the unions into new areas such as investment, planning, work organisation and design constitute a challenge to trade union core mandate. In some union circles there are fears about unions embracing what appear to be managerial strategies in a period of deep transformation and turbulence. Moreover, according to some union leaders any attempt by the unions to go beyond the “oppositional and defensive role” would result in a confusion and misrepresentation of their members' interests.
Public Day Care Centres, Company Day Care Centres, and Segregation Between Men and Women in the Labour Market: the Case of the Netherlands*
Authors: Schippers Joop J. , Siegers Jacques J.
Published: June 2007

Abstract. What is needed to diminish segregation between men and women in the labour market is a program of affirmative action for the Netherlands as a whole. Specific measures aimed at the removal of barriers between occupations cannot be successful unless they are imbedded in such an overall program. A necessary part of such a plan are facilities that enable women and men to combine unpaid parental tasks and paid labour. In contrast with public day care centres, company day care centres do not fit into such a plan, because they even enlarge existing segregation.

Company day care centres and other measures to facilitate parental care and paid labour are more often found in industries with a larger share of female workers. This relationship is found for both the Netherlands and the United States.

It is concluded that it is in the interest of employers as well as women's emancipation to increase the number of public day care centres instead of the number of company day care centres.
Union Bargaining, Wage Differentials and Employment
Authors: Bellmann Lutz , Emmerich Knut
Published: June 2007

Abstract. Reviewing empirical studies concerning the corporatism‐flexibility‐performance nexus the paper discusses decentralized and centralized bargaining systems. Revenue pay systems, concession bargaining and two‐tier wage systems as means to enhance wage flexibility at the firm level are also considered. Both theoretical and empirical evidence is presented, showing that unions are bargaining for greater employment security for the already employed (the insiders). In return, unions are ready to accept greater wage flexibility and even wage decreases. By contrast, the insider‐outsider theory does suggest how unions may accentuate involuntary unemployment, because there may be ways in which a union can help to raise the wages of the insiders without reducing their chances of continued employment.
Employers' Reactions to the Productivity Drive: the Search for Labour Consensus*
Authors: Regini Marino
Published: June 2007

Abstract. European employers' different policies of personnel management and of industrial relations depend to some extent on the technological and organisational choices they make, but cultural ‐ and especially institutional ‐ factors play an even greater role, in a period in which previous models for action clearly appear inadequate and in which, as a consequence, uncertainty grows.

This article illustrates a conceptual and analytical framework which helps understand the scope and the meaning of the recent managerial search for a greater labour consensus noted by many observers. Then it shows how this framework can be used, by applying it to the analysis of the Italian case. Finally, it tries to transform some of the propositions discussed into questions and hypotheses which should guide comparative research.
Trade Union Membership and the Free Rider Problem: the Role of Harassment Activities
Authors: Chiarini Bruno
Published: June 2007

Abstract. Although there exists an extensive literature which uses econometric techniques to examine the process of unionisation in the industrial countries, a well established theory about the individual propensity to join the union has still to be developed. We feel that the workers' personal relationships in the working places impinge on their decision to unionise. To this end, we have set out a coercion model of trade union membership without compulsory membership, based on the rank and file union members' harassment activities. Union members use these unfriendly activities to eliminate the free‐rider ploblem, encouraging unionisation and reducing the cost of joining a union.
Hypotheses for an Interpretative Model of Organizational Decision‐making at Strategic Level
Authors: Codara Lino
Published: June 2007

Abstract. Many problems that decision makers have to solve concern strategic environments. In such situations, the structural uncertainty they must face is overcome by using their representations of reality: people take decisions on the basis of their cognitive maps. In collective high level decision‐making, conflicts can rise among different frames and definitions of the problem. The process through which the actors can reach a joint solution has a bargaining nature. The decision‐makers' cognitive maps contain, besides the personal view of the problem to be solved, the perception of the position and bargaining power of the other actors. Strategic moves (commitments, threats…) can modify the partners' perceptions of the possibilities of success of their policy. As such, the decision‐makers' cognitive maps finally become “complementary”, permitting an agreement.
Labour Market Transitions of Youth and Prime Age Italian Unemployed
Authors: Ordine Patrizia
Published: June 2007

Abstract. Labour market transitions of different groups of Italian workers are analysed and typical working histories of young first‐job seekers and prime age unemployed compared. On the basis of a “search” theoretical framework a microeconometric analysis is undertaken by means of multinomial logit models applied to panel data on socio‐economic characteristics of Italian households. The results highlight the existence of phenomena of state and duration dependence. Moreover, while for prime age unemployed the behavioural distinction between unemployment and out of labour force states appears to be quite artificial, for young first‐job seekers it seems to be substantial.
Labour Institutions and Economic Growth: a Survey and a “Regulationist” Approach
Authors: Boyer Robert
Published: June 2007

Abstract. The paper argues that it is detrimental to assume perfect competition and total flexibility of labour markets in order to understand the intensity and stability of growth. Whereas development theories emphasize the impact of imperfect labour markets, this is not so for modern endogenous growth theories. By contrast, the régulation approaches (in the French meaning) both theoretically and empirically suggest that the transformations in labour institutions might have played a crucial role in the post World War II boom: an unprecedented division of labour associated with long‐run labour relations contracts have enhanced the genuine Fordist growth model. Furthermore, international comparisons among OECD countries suggest that job regulations and active minimum wage policies may have created some short‐run disequilibria but have stimulated dynamic efficiency, via more technological and organizational innovations. Consequently, this area requires more active researches by labour economists.
Unemployment in Urban China: an Analysis of Survey Data from Shanghai
Authors: Fu Gangzhan , Hussain Athar , Pudney Stephen , Wang Limin
Published: June 2007

Abstract. We analyse the unemployment problem in the largest Chinese city, Shanghai, based on a survey of the unemployed conducted in late 1989. We find, as expected, that unemployment is particularly serious among school‐leavers and contract and temporary workers, but also find a surprisingly high incidence of unemployment amongst permanent state employees and relatively long unemployment durations. The Shanghai unemployed rely heavily on occasional work for support, and only a small proportion‐receive state benefit. We identify problems of interpretation stemming from the stock‐sampling nature of the survey, and use non‐parametric methods to reveal an underlying strong downward movement in individual re‐employment probabilities.
Demographic Influences on the OECD Labour Market: Is there a problem? Are there solutions?*
Authors: Padoa Fiorella , Kostoris Schioppa
Published: June 2007

Abstract. This paper is concerned with the possible economic effects of the demographic movements expected to emerge in the OECD area over the next 30 years. It is argued that the labour and product market implications of the changing population size and ageing are not as worrying as conventional wisdom believes, especially if counterbalancing economic policies are implemented. The most negative effect will probably concern a potential productivity slowdown, but ageing might also have some positive side‐effects; implying, for example, declining youth unemployment.
Methodological Issues in Labour Economics: Procedures for Procedural Rationality?
Authors: Zappalà Gianni
Published: June 2007

Abstract. This paper examines methodological issues in labour economics, by examining the claim that it is moving closer to notions of procedural rationality advocated by Herbert Simon. A content analysis of the Journal of Labor Economics shows that the orthodox methodological perspective of deductivism has a strong hold in labour economics, and the nature of the empirical work is also allied to this perspective, casting doubts as to whether labour economics has moved towards procedural rationality. The paper then explores the possibilities of a bridge between labour economics and the schools of institutional labour economics and industrial relations. The paper argues that the former needs to borrow in a more constructive way from the latter in order to construct the procedures for procedural rationality.
Long‐Term Effects of a Plant Closure: a Multistate Duration Analysis of Event History Data in a Ten‐Year Follow‐Up Study
Authors: Rönsen Marit , Westin Steinar , Goldstein Harald , Ström Steinar
Published: June 2007

This paper discusses the possible effects on future prospects in the labour market of those who suffer a plant closure. A multistate duration model is estimated on monthly event data comprising 172 individuals over ten years, with the occurrence of the plant closure among the regressors. An individual can escape to one of several destinations when exiting one of three origin states (unemployed, sick leave, outside the labour force).

Our prime concern has been transitions leading to a new job or to destination states outside the labour force (disability pension and at home, without any social security benefit). We find indications of severe negative long‐term effects on employment from a plant closure: long durations in unemployment when searching for new jobs, higher incidence of leaving the labour force, longer periods of sick leave and higher incidence of disability pension. Thus, an adverse shock reducing employment may have negative long‐term effects on the labour market through long spells of unemployment and a shrinking labour force. Our findings thus support the hypothesis of hysteresis dynamics in the labour market.
Unemployment Components in the G7 Countries
Authors: Fiorito Riccardo , Padrini Flavio
Published: June 2007

Absrract

The increase in unemployment rates in the G7 countries is broken down into both labour supply and labour demand components. In no case is there a dominant source. Real GDP generally ranks first but does not account for more than a third of the overall changes. This finding shows that unemployment cannot be equated to negative employment since the labour force is generally increasing and volatile, mostly because of rising participation rates. Another reason why unemployment is not a reliable indicator of macroeconomic performance is that labour hoarding reduces employment response to output changes; this is especially true for Japan and Europe.
The Baumol Gap Revisited. An econometric analysis of the productivity differential between U.K. manufacturing and service firms, 1982–1989
Authors: Pellegrini Guido
Published: June 2007

The gap in productivity growth between manufacturing and service sectors is analyzed at company level using a panel of 328 British companies. This paper evaluates differences in the rate of growth of technological progresss (“Baumol gap”) in manufacturing and service companies, taking full account of the impact of changes in market competition, union recognition and financial position of firms. The empirical results suggest: (i) the gap in total factor productivity is significant and negative for distribution, lodging and catering sectors, positive but less significant for transport and communication sectors; (ii) the technological gap is higher than the gap in labour productivity; (iii) the gap can be attributed to technological factors, and it is invariant to the use of firm–level variables that capture effects on workers and managers effort; (iv) the estimate of total factor productivity growth in manufacturing and services is slightly influenced by these variables.
Unemployment and Search for Work: Exploratory Analyses of Labour Market Attachment and its Dynamics
Authors: Rettore Enrico , Torelli Nicola , Trivellato Ugo
Published: June 2007

This paper deals with measuring unemployment and labour market attachment in Italy, on the basis of Labour Force Survey data. Based on the answers to a set of questions on search for work, a cluster analysis is performed, which yields four groups, clearly characterized as regards their labour market conditions and attachment. Analyses are then carried out on the gross flows between these groups, estimated over a quarterly interval. Results of the dynamic analysis confirm the relevance of the classification established through exploratory techniques. The various groups exhibit a different dynamic behaviour, thus documenting that the exploratory classification has predictive power.
Monopoly Union Wage Setting and Evaluation of Public Projects: An Intertemporal General Equilibrium Approach
Authors: Lófgren Karl‐Gustaf
Published: June 2007

ABSTRACT This paper contains cost‐benefit rules for public projects in a small open economy with a tradeable and non‐tradeable sector, where wage setting is done by a representative household. The interpretation, with regard to traditional trade union theory, is in terms of a general equilibrium version of a monopoly union model. The intertemporal character of the model makes it possible to consider public projects which involve the creation of infrastructure that improves the future productivity of both labour and capital. A special feature of the model is the introduction of endogenous investment behaviour. However, since private investment is optimally adjusted in the initial equilibrium, envelope properties guarantee that first‐order projects will only have second‐order repercussions through changed investment behaviour, which means that indirect changes in private investment do not enter the project evaluation rules for small projects.
Wage Setting in Sweden: An Empirical Test of a Barebones Union Model
Authors: Forslund Anders
Published: June 2007

ABSTRACT In this paper a simple monopoly union model for the Swedish economy is presented and estimated. Interest is focused on the union's objectives. The results indicate that two popular representations of union objectives — wage bill and rent maximisation — are rejected by the data. Instead, preferences are highly concave in the wage rate, with an estimated degree of relative risk aversion well above unity evaluated at sample means.
Testing a Model of Trade Union Behaviour: An Application of a Multivariate Cointegration Analysis to UK Aggregate Wage Data
Authors: Fedeli Silvia
Published: June 2007

ABSTRACT The first part of the paper considers a behavioural model of trade unionism. Wages and employment are characterized as the outcome of a process by which the union maximizes an objective function containing wages and employment as arguments, and is constrained by a trade‐off between these two variables as represented by the firm's labour demand function. In the second part, the model's equilibrium predictions for wages are estimated in the framework of a multivariate error correction model and tested for cointegration with data from Britain's manufacturing sector from 1967 to 1986.
Marital Instability, Reproductive Behaviour and Women's Labour Force Participation Decisions
Authors: Tanda Paola
Published: June 2007

ABSTRACT The subject of this paper is the relationship between female labour force participation, fertility decisions and marital instability and pursues a two‐fold objective: to explain the nature of the interdependences between participation and procreation decisions; and to look for, through empirical evidence, an explanation for women's labour force participation and fertility dynamics over the last 20 years. The empirical evidence, based on a panel of 19 countries over the period 1965–1989, shows that variables representing marital instability have an important role in woman's labour supply and fertility dynamics during this period.
The Effects of Education on the Duration of Unemployment
Authors: Kettunen Juha
Published: June 2007

ABSTRACTThis paper studies the relationship between the level of education and the probability of re‐employment. Using a search theoretical model, it is shown that on the lowest levels additional education increases the probability of re‐employment, but on the highest levels the relationship turns negative. Finnish microeconomic data on unemployed workers show that unemployed people who have 13–14 years of education have the highest re‐employment probability.
Recruitment and the Role of Employment Services in Bulgarian Industry
Authors: Sziraczki Gyorgy , Windell James
Published: June 2007

ABSTRACT: This article is based on two surveys of Bulgarian manufacturing enterprises completed by the International Labour Organization in 1992 The surveys covering both state and private sector firms in this transition economy undergoing severe structural change collected a wealth of data on labour and employment practices at the micro level The authors examine recruitment and vacancy rates in the industrial sector managerial recruitment preferences on the basis of age gender and educational back ground and the recruitment methods used by managements in hiring workers The role of the national employment services in labour allocation is also analyzed revealing different recruitment strategies between state and private sector firms
The East German Wage Structure in the Transition to a Market Economy
Authors: Steiner Viktor , Bellmann Lutz
Published: June 2007

ABSTRACT: An important question for the development of the East German labour market in the transition to a market economy is whether wage differentials by qualification, industry or region (which were relatively small in the former GDR) adjust to those in market economies which are more in line with differences in productivities and economic conditions. We estimate empirical earnings functions to quantify the contribution of various important factors shaping the earnings distribution in the East German transition process. Estimation is based on the first six waves of the Labour Market Monitor which is a representative panel data set of the East German working‐age population covering the period 1990 to 1992. The specification of the estimated earnings functions is motivated by the various hypotheses of the development of the East German wage structure in the transformation process. Although we find some similarities with the existing wage structure in West Germany, the East German wage structure still differs in some important dimensions.
Union Density and Relative Wages: What is the Relationship?
Authors: Lucifora Claudio
Published: June 2007

ABSTRACT: This paper examines the impact of union density on relative wages under decentralised bargaining settings. Whilst, traditionally, empirical studies have focused on the impact of union status on wages (either at the individual or at the plant level), here it is argued that local trade union density can have an independent (positive) effect on wages. This occurs through the threat of collective action and the ability of the union to impose costs onto employers. First, a Nash bargaining model is presented under efficient‐bargaining settings, and a wage‐membership equation is derived. Wages are shown to be an increasing and convex function of union membership. Second, an empirical specification of the wage‐membership equation, suitable for estimation, is obtained and fitted to establishment‐level data for the Italian metal‐mechanical engineering industry. A positive monotonic relationship between wages and union density is detected. Furthermore, wages are shown to be increasing with union density even where no formal local bargaining agreement is in force, thus suggesting that “union‐threat” effects might be relevant.
The Productivity Slowdown in Postwar Greece
Authors: Mihail Dimitrios
Published: June 2007

Abstract. This article examines the two contrasting phases of labour productivity in postwar Greece. We present a model of trended labour productivity that synthesises mainstream technical factors, institutional arguments based on the social structure of accumulation framework, and Abramovitz's catch‐up hypothesis. The model is empirically estimated and the labour productivity growth is found to be sensitive to changes in capital intensity, proxies of power relations in the labour market, and a productivity convergence indicator.
The Incidence of Household Characteristics on Labour Decisions: The Case of Spain
Authors: Cebrián Inmaculada , Moreno Gloria
Published: June 2007

Abstract. This work presents an approach to the analysis of the incidence of family relationships on individuals' labour decisions as well as on their position in the labour market. We follow two different analyses. Firstly, we attempt to identify the type of households which are the most characteristic in our society to select the main categories of those where most people live, in order to study the decisions about participation in labour markets as well as the incidence of unemployment upon them. The second analysis tries to implement a model to allow us to study the implications of living in a partnership and the probability of both members of a couple having the same labour market status. There are at least two relevant results: the first shows the important concentration of unemployment in households of a couple with adult children and is clearly related to youth and female unemployment and the necessity of political intervention to correct them. The second points out the dependence between the labour status of the couple, mainly when they have a low level of education. Nevertheless, the woman is usually inactive, although this situation tends to change the younger she is, in which case the highest probability is that both members of the couple are employed.
Wage Premium in the Industrial Sector of the Spanish Economy: Empirical Evidence
Authors: Sánchez Rosario , Urbano Amparo , Ortí Angel
Published: June 2007

Abstract. This paper presents evidence that firm‐level productivity increases when the relative wage rises, or the level of unemployment rises. Both facts are consistent with the efficiency wage model. Moreover, there is support for the idea that an increase in the sector's wage with respect to the previous year also increases productivity. We obtain the empirical evidence through a double‐hurdle model. We use this estimation technique because it can be established that the differences in productivity between sectors could be explained by differences in effort. It means that some of the industrial sectors of the Spanish economy may pay wage premia while others do not. We also test this implication through panel data.
Organization and Work Situations: Which sources for the learning process?
Authors: Grasser Benoît
Published: June 2007

ABSTRACT: The observation of economic activity grants an equally important place to learning as some recent theoretical problems. However, what is meant by learning, and what in the productive activity enables the application of the learning process? This paper examines the notion of learning, as far as the firm is concerned, putting the emphasis on two main directions. On one hand, learning is not only a dynamic but also a process: it is not only a matter of going from one point to another, but also a process of construction of knowledge and rules. On the other hand, this process must be understood as an articulation between individual and organizational learning.
Immigration and Occupational Crowding in the United States
Authors: Stevans Lonnie K.
Published: June 2007

ABSTRACT:The 1990 National Longitudinal Survey of Youth is utilized to explore the effects that the occupational crowding of immigrants has on the real wages of indigenous and non‐US citizen workers already in the United States. Findings include adverse wage effects as a result of the crowding of immigrants on the following worker categories: (1) indigenous, unskilled, white or black workers and (2) non‐US citizen, skilled or unskilled black workers. Foreign‐born, skilled, and white workers already in the US realize a positive effect on their real wages as a result of having a large relative number of non‐US citizens in their occupations.
Discrimination as Collusion in Imperfectly Competitive Labour Markets
Authors: Naylor Robin
Published: June 2007

ABSTRACT: Despite growing evidence on the potential influence of monopsony power in modern labour markets, the standard monopsony theory of discrimination, at least with respect to pay differences by gender, is inconsistent with the empirical evidence on the association between relative pay and comparative labour supply elasticities. In this paper, we develop a general oligopsony model in which we argue that differences in the conjectural variation parameter can reconcile the empirical evidence with a model of discrimination based on imperfect competition in the labour market. Discrimination emerges from asymmetric collusion in the presence of employer power, without the need to incorporate a Beckerian‘taste for discrimination’parameter.
An Evaluation of Child Support Reforms
Authors: Boca Daniela Del
Published: June 2007

ABSTRACT: Among the policy changes proposed in the United States for determining equitable child support orders there is the proportionate order, which consists in setting orders as a percentage of the non‐custodial parent's income and wage withholding which involves the improvement of the procedure of collection of child support payments with the use of automatic withholding.

In this paper we use US data to compare proportionate and fixed child support awards and the interaction of these order types with wage withholding. We conduct an empirical investigation of the effects of these systems on divorced fathers’child support transfer. Our empirical results show that wage withholding tends to alleviate the problem of non‐compliance, while proportionate orders do not.
Time Out for Childcare: Signalling and Earnings Rebound Effects for Men and Women
Authors: Stafford Frank P. , Sundström Marianne
Published: June 2007

ABSTRACT: The wage cost of time out of the labor force for childcare is important in order to understand the functioning of labor markets and for public policy. This paper reviews the literature and identifies several limitations. Using employment records of a large Swedish company over the period 1983‐88, we demonstrate an alternative approach for estimating earnings effects and find a year out costs 1.7 percent of earnings for a woman and 5.2 percent for a man. This large effect for men raises questions of signalling costs. For both men and women, earnings‘'rebound'’for time out in the more distant past.
Assessment of the performances of multilayer perceptron neural networks in comparison with recurrent neural networks and two statistical methods for diagnosing coronary artery disease
Authors: Süt Necdet , Şenocak Mustafa
Published: June 2007

Abstract:We aimed to examine the diagnostic performances of multilayer perceptron neural networks (MLPNNs) for predicting coronary artery disease and to compare them with different types of artificial neural network methods, namely recurrent neural networks (RNNs) and two statistical methods (quadratic discriminant analysis (QDA) and logistic regression (LR)). MLPNNs were trained with backpropagation, quick propagation, delta‐bar‐delta and extended delta‐bar‐delta algorithms as classifiers; the RNN was trained with the Levenberg–Marquardt algorithm; LR and QDA were used for predicting coronary artery disease. Coronary artery disease was classified with accuracy rates varying from 79.9% to 83.9% by MLPNNs. Even though MLPNNs achieved higher accuracy rates than the statistical methods, LR (73.2%) and QDA (58.4%), their performances were lower compared to the RNN (84.7%). Among the four different types of training algorithms that trained MLPNNs, quick propagation achieved the highest accuracy rate; however, it was lower than the RNN trained with the Levenberg–Marquardt algorithm. RNNs, which demonstrated 84.7% accuracy and 86.5% positive predictive rates, may be a helpful tool in medical decision making for diagnosis of coronary artery disease.
Decision‐making method using a visual approach for cluster analysis problems; indicative classification algorithms and grouping scope
Authors: Bittmann Ran M. , Gelbard Roy M.
Published: June 2007

Abstract: Currently, classifying samples into a fixed number of clusters (i.e. supervised cluster analysis) as well as unsupervised cluster analysis are limited in their ability to support ‘cross‐algorithms’ analysis. It is well known that each cluster analysis algorithm yields different results (i.e. a different classification); even running the same algorithm with two different similarity measures commonly yields different results. Researchers usually choose the preferred algorithm and similarity measure according to analysis objectives and data set features, but they have neither a formal method nor tool that supports comparisons and evaluations of the different classifications that result from the diverse algorithms. Current research development and prototype decisions support a methodology based upon formal quantitative measures and a visual approach, enabling presentation, comparison and evaluation of multiple classification suggestions resulting from diverse algorithms. This methodology and tool were used in two basic scenarios: (I) a classification problem in which a ‘true result’ is known, using the Fisher iris data set; (II) a classification problem in which there is no ‘true result’ to compare with. In this case, we used a small data set from a user profile study (a study that tries to relate users to a set of stereotypes based on sociological aspects and interests). In each scenario, ten diverse algorithms were executed. The suggested methodology and decision support system produced a cross‐algorithms presentation; all ten resultant classifications are presented together in a ‘Tetris‐like’ format. Each column represents a specific classification algorithm, each line represents a specific sample, and formal quantitative measures analyse the ‘Tetris blocks’, arranging them according to their best structures, i.e. best classification.
Noninvasive models to predict liver cirrhosis in patients with chronic hepatitis B
Authors: Kim Beom Kyung , Kim Sung Ae , Park Young Nyun , Cheong Jae Youn , Kim Hwa Sook , Park Jun Yong , Cho Sung Won , Han Kwang‐Hyub , Chon Chae Yoon , Moon Young Myoung , Ahn Sang Hoon
Published: June 2007

Objectives: Few noninvasive models of chronic hepatitis B (CHB) to predict liver cirrhosis have been studied. The aim of the current study is to investigate the diagnostic accuracy of two simple novel models of spleen–platelet ratio index (SPRI) and age–spleen–platelet ratio index (ASPRI) in patients with CHB.

Patients and methods: A total of 346 consecutive treatment‐naïve patients with CHB were retrospectively studied. The aspartate to alanine aminotransferase ratio (AAR), age–platelet index (API), aspartate aminotransferase to platelet ratio index (APRI), SPRI, and ASPRI were compared with liver histology.

Results: AAR, APRI, SPRI, API, and ASPRI correlated significantly to fibrosis stage (all P<0.001). The diagnostic accuracy of ASPRI was the highest among five tests for prediction of cirrhosis (area under receiver operating characteristic curve, AUROC=0.893). Using a cutoff score of ASPRI>12, the presence of cirrhosis could be correctly identified with a high accuracy (96.3% positive predictive value) in 35 (10.1%) of 346 patients. Similarly, using a cutoff of <5, the presence of cirrhosis could be totally excluded with 100% of negative predictive value in 120 (34.7%) of 346 patients.

Conclusion: ASPRI was accurate in predicting cirrhosis and screening with ASPRI has the potential to reduce the number of liver biopsies in CHB patients.
Ethosuximide: From Bench to Bedside
Authors: Gören M. Zafer , Onat Filiz
Published: June 2007

Ethosuximide, 2‐ethyl‐2‐methylsuccinimide, has been used extensively for “petit mal” seizures and it is a valuable agent in studies of absence epilepsy. In the treatment of epilepsy, ethosuximide has a narrow therapeutic profile. It is the drug of choice in the monotherapy or combination therapy of children with generalized absence (petit mal) epilepsy. Commonly observed side effects of ethosuximide are dose dependent and involve the gastrointestinal tract and central nervous system. Ethosuximide has been associated with a wide variety of idiosyncratic reactions and with hematopoietic adverse effects. Typical absence seizures are generated as a result of complex interactions between the thalamus and the cerebral cortex. This thalamocortical circuitry is under the control of several specific inhibitory and excitatory systems arising from the forebrain and brainstem. Corticothalamic rhythms are believed to be involved in the generation of spike‐and‐wave discharges that are the characteristic electroencephalographic signs of absence seizures. The spontaneous pacemaker oscillatory activity of thalamocortical circuitry involves low threshold T‐type Ca2+currents in the thalamus, and ethosuximide is presumed to reduce these low threshold T‐type Ca2+currents in thalamic neurons. Ethosuximide also decreases the persistent Na+and Ca2+‐activated K+currents in thalamic and layer V cortical pyramidal neurons. In addition, there is evidence that in a genetic absence epilepsy rat model ethosuximide reduces cortical γ‐aminobutyric acid (GABA) levels. Also, elevated glutamate levels in the primary motor cortex of rats with absence epilepsy (but not in normal animals) are reduced by ethosuximide.
Glatiramer Acetate in Multiple Sclerosis: A Review
Authors: Ruggieri Maddalena , Avolio Carlo , Livrea Paolo , Trojano Maria
Published: June 2007

Multiple sclerosis (MS) is considered to be primarily an inflammatory autoimmune disease. Over the last 5 years, our view of the pathogenesis of MS has evolved considerably. The axonal damage was recognized as an early event in the disease process and as an important determinant of long‐term disability. Therefore, the antiinflammatory and neuroprotective strategies are thought to represent promising approach to the therapy of MS. The therapeutic potential of glatiramer acetate (GA), a synthetic amino acid polymer composed of a mixture of l‐glutamic acid, l‐lysine, l‐alanine, and l‐tyrosine in defined proportions, in MS has been apparent for many years. GA has been shown to be effective in preventing and suppressing experimental allergic encephalomyelitis (EAE), the animal model of MS. GA has been, therefore, evaluated in several clinical studies and found to alter the natural history of relapsing‐remitting (RR)MS by reducing the relapse rate and affecting disability. These findings were confirmed in open‐label follow‐up trials covering more than 10 years of treatment. The trials demonstrated sustained efficacy for GA in slowing the progression of disability. The clinical therapeutic effect of GA is consistent with the results of magnetic resonance imaging (MRI) findings from various clinical centers. At a daily standard dose of 20 mg, s.c., GA was generally well tolerated. The induction of GA‐reactive T‐helper 2‐like regulatory suppressor cells is thought to be the main mechanism of the therapeutic action of this drug. In addition, it was recently shown that GA‐reactive T cells produce neurotrophic factors (e.g., brain‐derived neurotrophic factor [BDNF]) that protect neurons and axons in the area of injury.
Variations of L*a*b* Values among Vitapan® Classical Shade Guides
Authors: King Kenneth A. , DeRijk Waldemar G.
Published: June 2007

Purpose:
To measure the variations in L*a*b* values of a group of 25 guides and to assess whether shade guides are indeed interchangeable.

Materials and Methods:
The L*a*b* values of individual shade tabs were measured with a LabScan(tm) XE scanning spectrocolorimeter (SSC) with a special attachment for reproducibly positioning shade tabs. Each shade guide (Vitapan Classical, Vident) contained 16 shade tabs. Absolute calibration of the SSC was performed with color tiles traceable to NIST. One shade guide was used to determine the reproducibility of the experimental method by measuring and then removing each shade tab of the standard 10 times. This assessed the variations in observed values induced by the measurement method and the geometry of the specimens. The entire sample consisted of 25 shade guides. The tabs of each of the 25 shade guides were read five times in the SSC, without moving the specimen. Measurements and calculations of E, L*, a*, and b* were performed using Universal Software V4.10 (Hunter Associates Laboratory). The mean, standard deviation, and range were determined of the E, L*, a*, and b* values for each one of the 16 shades in the shade guides. Differences in color are expressed as ΔE in color science. The standard deviation of E (Esd) and the range of E (Er) for each of the shades were used as a ΔE value to assess color differences.

Results:
For the reproducibility measurements, the shades had values for Er varying from 0.08 to 0.69, and Esd between 0.02 and 0.22. This established the detection limit for our method for each of the shades. For the group of 25 shade guides, Er varied from 0.75 to 3.05, and Esd from 0.22 to 0.54. The difference in value of Er obtained from the reproducibility test and the Er of the group of 25 guides is significant at p < 0.05. The same was found for Esd. The largest reproducible Er observed was 3.05 for shade C1.

Conclusions:
The differences observed between shade guides are larger than the variations induced by the experimental method. The difference in E values for the shades C1 and C2 is 2.19; hence the observed Er of 3.05 between shade tabs of the same shade (C1) is larger than the changes in color between shades. This large a variation in what are claimed as identical shade tabs is deemed of clinical importance, and therefore, the shade guides should not be considered interchangeable.
The Effect of a Constant Electrical Field on Osseointegration after Immediate Implantation in Dog Mandibles: A Preliminary Study
Authors: Shayesteh Yadollah Soleymani , Eslami Behnam , Dehghan Mohammad Mehdi , Vaziri Hamed , Alikhassi Marzyeh , Mangoli Amir , Khojasteh Arash
Published: June 2007

Purpose:
The long time span between insertion of implants and functional rehabilitation often inconveniences patients. Accelerating bone growth around dental implants can shorten this time span. This in vivo study evaluated the effect of a constant electrical field on bone growth around dental implants.

Materials and Methods:
Four mongrel dogs were used in this study. Sixteen dental implants were placed immediately after extraction of the first premolar and molar teeth. A constant electrical field (CEF) generator was placed in the mucoperiostal pouch created from the subperiostral dissection under the inferior border of the dog's mandible and connected to the experiment side fixtures. CEF provided 3 V of electrical potential during osseointegration. Histologic sections were stained with hematoxylin–eosin and observed under light microscopy. The sections were analyzed histomorphometrically to calculate the amount of newly formed bone. Statistical analysis was performed with SPSS 11.0 computer software (α= 0.05).

Results

: At the end of the first stage of the osseointegration (90 days) CEF group sections showed enhanced growth of the trabeculae compared with the control group. Statistical analysis revealed significant differences between experimental and control groups. Bone contact ratio was statistically significant in the experimental group (p= 0.001). An increase in the local bone formation and bone contact ratio was observed with direct electrical stimulation of the implant and the bone area around the implant.

Conclusion:
Minimal direct electrical current, which can produce an electrical field around the implant, can increase the amount of bone formation and decrease the time of osseointegration.
Problem‐based Learning in Undergraduate Dental Education: Faculty Development at the University of Southern California School of Dentistry
Authors: Saunders Timothy R. , Dejbakhsh Shireen
Published: June 2007

The University of Southern California School of Dentistry (USCSD) seeks to educate oral health professionals with a balanced curriculum covering health promotion, risk assessment and disease prevention, diagnostics, treatments, and therapeutics. Based on critical analyses of a 5‐year educational demonstration project, the USCSD proposed to use problem‐based learning (PBL) to achieve its goals. Among the many changes required to convert a traditional dental educational curriculum to PBL, none is more important than that of faculty development. To achieve this, the USCSD Curriculum Subcommittee on Faculty Development, Mentoring, and Evaluation has designed and implemented a series of workshops to train its faculty as facilitators. There are four Core Skills Workshops: PBL Process Workshop, Facilitation of Learning Workshop, Student Assessment and Feedback Workshop, and PBL in the Clinical Environment.