bluuebunny/crossref_metadata_2025 huggingface dataset:
The impact of the foreign corrupt practices act on us exports
Authors: Beck Paul J. , Maher Michael W. , Tschoegl Adrian E.
Published: May 2007

In 1977 the Foreign Corrupt Practices Act (FCPA) was enacted to penalize US firms and their employees for paying bribes to foreign government officials. If bribe payments influence the awarding of contracts and the FCPA regulation differentially affects US exporters compared to foreign competitors, then US exporters' bribe‐paying ability and market share would be expected to decline. This study provides empirical evidence that the FCPA had a negative effect on US exports to non‐Latin American countries but not to bribery prone ones in Latin America.
Price‐matching policies: An empirical case
Authors: Hess James D. , Gerstner Eitan
Published: May 2007

Promises by retailers to match the prices of their competitors give an impression of fierce price competition. These policies, however, may deter rivals from cutting prices because the threat of price matching makes it more likely that market share will not be gained. This paper empirically tests these two conflicting theories using data collected from grocery stores in a market where several stores had announced that they would match the prices of the low‐price supermarket. The evidence supports the theory that price‐matching policies help supermarkets avoid price competition and therefore lead to generally higher prices.
The effects of mergers on price and output: Two case studies from the airline industry
Authors: Werden Gregory J. , Joskow Andrew S. , Johnson Richard L.
Published: May 2007

The literature on industrial organization contains very little direct evidence on the effects of actual mergers. This study estimates the effects of two recent airline mergers approved by the Department of Transportation over the objection of the Department of Justice. The merger of TWA and Ozark appears to have caused a slight increase in fares and a far greater reduction in service on city pairs out of St Louis. The merger of Northwest and Republic appears to have caused a significant increase in fares and a significant reduction in overall service on city pairs out of Minneapolis‐St Paul.
Accounting choice: The role of monitoring costs
Authors: Knoeber Charles R. , McKee A. James
Published: May 2007

Focusing on monitoring costs, the agency framework is used to extend and test the positive theory of accounting choice. To reduce monitoring cost, a firm is predicted to adopt those accounting methods employed by other firms facing the most similar economic environment. This allows the firm's shareholders (typically acting through the Board of Directors) to use the performance of these other firms to better impute and reward its own manager's performance. This hypothesis is tested and supported by examining, for a sample of industrial firms, the choice of depreciation method.
Divisional sell‐off: A hazard function analysis
Authors: Ravenscraft David J. , Scherer F. M.
Published: May 2007

For a sample of roughly 450 companies, hazard function estimation is used to determine the environmental and organizational variables precipitating the ‘sell‐off’ of divisional units. The sample focuses on 285 ‘lines of business’ fully divested between 1975 and 1981, comparing them to 2157 retained lines. The most powerful sell‐off predictor was prior profitability at the line of business level; the lower profits, the higher the sell‐off probability. Also, divestiture was more likely, the lower company‐wide profitability, the lower a line's market share, the lower the line's R&D/sales ratio, and in the aftermath of a company chief executive officer change. Units previously acquired in conglomerate mergers were more likely to be sold off than original units. On the buyer's side of the sell‐off market, large companies acquiring other firms' divested units tended to improve the units' profit performance, but not enough, on average, to realize a normal return on their investments.
Retail pricing: Does channel length matter?
Authors: Coughlan Anne T. , Lal Rajiv
Published: May 2007

The number of intermediary levels between a manufacturer and the final market in a distribution channel varies from industry to industry. In some cases, none are used (i.e. the distribution function is vertically integrated), while several middleman levels are used in other cases (e.g. the use of a wholesaler, a jobber, and a retailer in the distribution of meat). In this paper we examine the effect of competition on the profit‐maximizing length of the distribution channel. We find that the optimal number of middleman levels increases with the substitutability of products in the market, but that there are institutional limits on the maximum number of levels in a channel. The analysis also suggests that differences in the objectives of channel members (e.g. the maximization of total channel profit versus the maximization of each member's individual profit) affect optimal channel length: a goal of total channel profit maximization produces a channel at least as long as one of individual (non‐co‐operative) member profit maximization. The work thus complements existing research focusing on intra‐channel (e.g. cost‐based) explanations of channel length, using a framework similar to those investigating competitive incentives for vertical integration in distribution.
Personal Taxes and the underpricing of initial public offerings
Authors: Dandapani Krishnan , Dossani Rafiq , Prakash Arun J. , Reside Mary Ann
Published: May 2007

The purpose of this paper is to propose an alternative explanation for the underpricing of initial public offerings (IPOs). The first section reviews the empirical evidence on underpricing IPOs in support of various alternative hypotheses that have been put forth in the literature. This is followed by our model which examines the effect of personal taxes paid by entrepreneurs on the choice of the issue price. We show that, in the presence of taxes and for certain levels of ownership retained by the entrepreneur, it may be preferable to underprice the issue. This theoretical result is reinforced by both the simulation and empirical tests.
Organizational structure and the internal economy of the firm: The UK insurance industry
Authors: Ingham Hilary
Published: May 2007

There now exists a substantial volume of empirical evidence which has examined the superiority of the ‘M’‐form organizational structure for the management of large, diversified enterprises. Regrettably, attention has mainly been focused on manufacturing companies, despite the rising importance of the service sector in most major economies. This paper examines organizational structures within one segment of the UK service sector: the insurance industry. In the UK this industry has undergone significant, regulatory‐driven structural change and, as a consequence, the majority of companies have undertaken organizational change. The results produced, however, suggest that many of these companies adopted sub‐optimal divisionalized structures.
The factors determining the profitability of international airlines: Some econometric results
Authors: Antoniou Andreas
Published: May 2007

The deregulation of the US domestic airline market in 1978 and its apparent relative success continues to attract a great deal of interest among US and other economists. This uniquely US experience has clearly shown that factors such as market contestability, the multiple output nature of costs, the structure of networks and airport presence play a crucial role in the survival and, ultimately, profitability of relatively free and unregulated airlines. However, most international airlines still operate in a heavily regulated environment. While the tendency is clearly toward liberalization, the question remains: What can these airlines do to improve their profitability within this framework? Our results indicate that profitable airlines have high passenger load factors, a relatively low proportion of capacity related costs, younger and more efficient fleets and supplement their passenger loads with freight.
The market reaction to announced deep cuts in capital expenditures
Authors: Tsay Yang‐Tzong , Alt Frank , Gordon Lawrence A.
Published: May 2007

The objective of the study reported in this paper was to examine the role of deep cuts in capital expenditures as a firm's strategy for becoming more efficient and, in turn, more competitive. Based on an empirical study, support is provided for the argument that deep cuts in capital expenditures may be a viable strategy for realigning corporate priorities toward a more efficient operation. The measure of performance utilized in this paper is the stock market reaction to announced deep cuts.
Restructuring, regrouping and adjusting: Canadian manufacturing in an era of free trade and globalization
Authors: Weiermair Klaus , Supapol Atipol Bhanich
Published: May 2007

This paper examines the international competitiveness of the Canadian Textile and Clothing (TC) sector and its adjustment problems within a global economy. It focuses on the TC firms' capabilities to prepare for changes and implement strategies in an increasingly turbulent market environment. It highlights the importance of organizational response mechanisms and the development/utilization of industry‐specific technology and management know‐how. The paper argues for a future Canadian industrial policy that emphasizes the achievement of dynamic as well as static efficiency.
The dynamic operation of the market for partnership deeds in a duopolistic industry of a profit‐maximizing firm and workers' enterprise
Authors: Chiarella Carl
Published: May 2007

This paper analyses a model of the dynamic interaction of a profit‐maximizing firm and a workers' enterprise (in the sense of Sertel, 1982) in an industry in which each acts as a duopolist. The framework is similar to that of Chiarella (1992). In that study labour was the only factor of production and workers were allowed to trade‐off work and leisure. Here we wish to analyse the effect of the capital accumulation decision on the outcome of the duopolistic competition. In order to obtain a tractable model we drop the work‐leisure trade‐off. We assume dynamic adjustment in the market for partnership deeds along the lines suggested by Okuguchi (1992a, b) and analyse the equilibrium of the duopoly, its comparative statics and stability with respect to key variables.
Optimum tariff on imports from imperfectly competitive labor‐managed firms
Authors: Hwang Hong , Lin Yen‐Shu , Mai Chao‐Cheng
Published: May 2007

This paper develops a model of international trade between a labor‐managed economy and a capitalist economy and examines the short‐ and long‐run optimal specific tariff in the presence of foreign imperfect competition among labor‐managed firms. It will be shown that the underlying conditions for the optimal tariff rule are different from conventional wisdom.
The productivity effects of employee ownership within command economies: Evidence from Poland
Authors: Jones Derek C.
Published: May 2007

The effects of employee ownership, broadly defined, are estimated for a sample of Polish producer co‐operatives in three industries during 1976‐8, i.e. when Poland was a centrally planned economy. The results indicate that, in general, increasing either worker participation in control and/or in economic returns provides positive effects on productivity. The pattern of the different effects of employee ownership varies significantly across sectors. This new evidence strongly suggests that workers within Soviet‐type economies are responsive to economic incentives. Together with existing theoretical and empirical evidence for both Eastern and Western European firms, the findings suggest a larger role for employee ownership than typically either currently exists or that is under serious consideration in most restructuring economies.
The influence of executive compensation on the dispersion of security analyst forecasts
Authors: Goss Betsy C. , Waegelein James F.
Published: May 2007

This study examines the association between executive compensation and security analyst forecast dispersion in an agency setting. It is hypothesized that firms that compensate their managers with long‐term performance plans and high percentages of managerial stock will be less likely to engage in manipulation of financial statements and their financial performance will be easier to predict, thus resulting in less disperse forecasts. The results provide evidence that firms that compensate their managers with long‐term performance plans and higher levels of the company stock have less dispersion associated with their security analyst forecasts and greater dispersion of their long‐term growth in earnings.
Chance‐constrained data envelopment analysis
Authors: Land Kenneth C. , Lovell C. A. Knox , Thore Sten
Published: May 2007

Data envelopment analysis (DEA) is extended to the case of stochastic inputs and outputs through the use of chance‐constrained programming. The chance‐constrained frontier envelops a given set of observations ‘most of the time’. As an empirical illustration, we re‐examine the pioneering 1981 study of Program Follow Through by Charnes, Cooper and Rhodes.
Note: Heteroscedasticity in the market model: Some evidence from the athens stock exchange
Authors: Karathanassis G. , Philippas N.
Published: May 2007

Over the last three decades a substantial amount of empirical research has been undertaken to investigate the behaviour of major securities markets. While some work has been done with data from the markets of developing countries, considerable testing must be undertaken for the world's emerging securities market. The objective of this paper is to present some Greek evidence of the heteroscedasticity in the market model. The paper examined 43 companies quoted on the Athens Stock Exchange and found substantial evidence of heteroscedasticity.
Firm‐specific wage growth and changes in the labor market for managers
Authors: Chauvin Keith W.
Published: May 2007

This paper analyzes recent changes in the employment relationships between managers and firms. In both Becker's and Lazear's models of firm‐specific wage growth, compensation is deferred from early in an employee's tenure with a firm until later in the contract. The deferred compensation bonds the worker to the firm. Based on cross‐sectional data from Current Population Surveys, rates of firm‐specific wage growth are estimated for the managerial labor market. The findings show that the rate of wage growth that is firm‐specific for managers in manufacturing industries declined significantly during the early 1980s. It is estimated, for example, that a manager with 12 years of tenure in a manufacturing firm enjoyed, on average, a 25% wage premium in 1979 over an otherwise similar manager who was a new hire in a firm. By 1983 the firm‐specific wage premium for a manager with 12 years of tenure was only 5%. These changes represent a significant reduction in the strength of the employment bond between firms and managers, and a reduction in the incentive effects previously enjoyed by firms from the use of deferred‐compensation schemes. This change is consistent with the significant increases in the displacement rates of managers that occurred during the 1980s.
On the manager as principal clerk
Authors: Horowitz Ira
Published: May 2007

Until recently, economic theory and economists treated the management process with benign neglect. Insofar as business enterprises — the firms of economic theory – require managers to oversee their daily operations, these managers are implicitly viewed as fungible ‘principal clerks’. This paper makes this view explicit and considers whether it is valid for a particular class of manager, that of a major league baseball team.
Are baseball players paid their marginal products?
Authors: Macdonald Don N. , Reynolds Morgan O.
Published: May 2007

Previous researchers found that baseball players under the reserve clause had been paid considerably less than their contributions to club revenues. We ask, has the new contractual system of free agency and final‐offer arbitration brought baseball salaries into line with marginal revenue products? Using public data for the 1986 and 1987 seasons, our basic answer is yes, major league salaries generally coincide with estimated marginal revenue products, though significant deviations exist. Experienced players are paid in accord with their productivity; young players, however, are paid less than their marginal revenue product, on average. This result is closely related to the market structure within baseball.
Free Agency and the Allocation of Labor in Major League Baseball
Authors: Krautmann Anthony C. , Oppenheimer Margaret
Published: May 2007

In this paper we examine the allocation of labor under free agency by developing and testing a model to predict the migration of free agents. Data for individual players are used in a logit model that estimates the probability that a free agent will change teams as a function of several independent variables. Along with other authors, we find that free agents tend to migrate to big cities. In addition, we find evidence that the allocation of labor may be different under free agency than under the reserve clause and suggest a reason why Coase's theorem may not be applicable to this labor market.
US professional football: The demand for game‐day attendance in 1991
Authors: Welki Andrew M. , Zlatoper Thomas J.
Published: May 2007

This paper examines the factors which affect game‐day attendance at National Football League games during the 1991 season. Using a Tobit analysis, the model includes economic as well as quality of game variables as explanatory variables. This analysis reveals that: higher ticket prices reduce attendance with the demand appearing to be inelastic; and a winning home team spurs game‐day attendance.
Estimating the economic impact of a minor league baseball stadium
Authors: Colclough William G. , Daellenbach Lawrence A. , Sherony Keith R.
Published: May 2007

Minor league baseball has enjoyed a renaissance in recent years. In many communities baseball supporters are proposing sports stadiums often with some degree of tax support requiring voter approval. Economic growth and development are issues citizens are asked to consider when they vote. This paper presents an easily adaptable model for estimating the direct and indirect economic impact of a minor league baseball team on the community. An application of the model is featured. Direct expenditures from external sources are estimated and RIMS II regional multipliers are applied to determine the indirect impact on area output, earnings and employment.
Take that jam! An analysis of winning percentage for NBA teams
Authors: Chatterjee Sangit , Campbell Martin R. , Wiseman Frederick
Published: May 2007

The won‐loss percentage for all games played in a season by NBA teams is modeled as a function of team performance statistics. Four variables field goals, free throws, rebounds, and turnovers are found to be statistically significant and account for more than 90% of the variation in the data. The regression coefficients also appear to be stable from year to year. Predictions for four years obtained from the estimates of one season show good agreement with the observed data. Forecasts for the 1993 season are also given based on mid‐season statistics. Predictions for play‐off winners are also briefly discussed. The analysis is carried out in the spirit of exploratory data analysis using graphical methods.
Salary determination in major league Baseball: A classroom exercise
Authors: Estenson Paul S.
Published: May 2007

As a part of an economics course, The Economics of Major League Baseball, students were assigned the responsibilities of team owners who had to assess the quality and value of players, put a product on the market (their baseball team), pay salaries and maximize profits. The season was simulated using the Earl Weaver Baseball software and involved a schedule of 162 games for each team. The exercise was used to examine salary determination in major league baseball. The exercise was modelled as closely as possible to the actual structure of major league baseball with the clearest distinction being the acquisition of players. The owners in the experiment purchased players in the open‐outcry English auction. The results of the auction showed that salaries matched marginal revenue products and that the open auction displayed the declining price anomoly discovered to exist in real‐world auctions.
Labor market reputation and the value of the firm
Authors: Chauvin Keith W. , Guthrie James P.
Published: May 2007

This study examines the stock market reaction to announcements that should contribute to the positive reputation of firms' human resource management practices. Announcements consist of the annual release of the list of 'best' employers by Working Mother magazine. We hypothesize that these announcements positively contribute to the firms' labor market reputation, thereby improving a firm's ability to attract, retain and motivate good employees. We find a small but statistically significant increase in firms' stock prices following the release of the list. The effect is larger, the first time a firm appears on the list relative to subsequent appearances.
A tax‐based motive for the underpricing of initial public offerings
Authors: Reside Mary Ann , Robinson Richard M. , Prakash Arun J. , Dandapani Krishnan
Published: May 2007

This paper presents a model of entrepreneurial wealth maximization for the pricing of initial public offerings (IPOs). It is an extension of one previously presented in the literature. The model shows that personal tax rates on ordinary income and capital gains may, in part, determine IPO pricing: an increase in the capital gains tax rate should lower the degree of underpricing. An empirical analysis of the effect of the Tax Reform Act of 1986, which raised the capital gains tax rate, shows that the average degree of underpricing did decrease as predicted, and that this occurs after controlling for other possible influences.
Simulations testing the performance of three product pricing rules when applied using data on past operations
Authors: Lere John C.
Published: May 2007

This paper describes the performance of learning, markup and pseudo‐maximizing pricing rules when applied using data on past operations in simulated environments. Performance is evaluated on (1) average last profit achieved after ten periods of experimentation with alternative prices and (2) total profit achieved over ten periods. The pseudo‐maximizing rule performs at least as well as other feasible rules when the demand and cost curves are both deterministic and when the demand curve is deterministic and the cost curve is linear, but stochastic. In all other settings, the markup rule performs at least as well as other feasible rules.
Sole sourcing, competitive sourcing, parallel sourcing: Mechanisms for supplier performance
Authors: Richardson James , Roumasset James
Published: May 2007

Quality management practitioners in the USA such as W. Edwards Deming, strongly advocate the Japanese model of supplier relationships‐recommending substantial specific investment in a single supplier for improved co‐ordination and higher quality. But the strategy literature and conventional wisdom favor multiple sourcing, suggesting that a high level of specific investment in a sole source will lead to problems with supplier performance. Using agency theory, we construct a model to evaluate the tradeoff between the costs to set up and coordinate with suppliers and the incentive for performance provided by competition. We find that the validity of Deming's Point Four, that sole sourcing is more profitable than competitive sourcing, depends on parameters such as profit sensitivity to supplier performance.
Note: A pilot experimental test of trade hysteresis
Authors: Ansic David
Published: May 2007

Developing tests of the theories of trade, using traditional empirical and econometric techniques, has been shown to be controversial and inconclusive. This paper reports on some encouraging results arising out of a pilot experiment designed to test the Krugman model of trade hysteresis. This pilot experiment reveals that a definite hysteresis effect is evident when subjects exit a foreign market in which they have been trading after having paid fixed costs to enter the market. Results also show that the degree of hysteresis evident is a function of the absolute and relative size of entry costs, which has implications for the relationship between size of business, volatility of exchange rates and international trade.
The role of takeovers in increasing efficiency
Authors: Grabowski Richard , Mathur Ike , Rangan Nanda
Published: May 2007

This paper extends the limited number of studies that examine whether the threat of takeovers serves as an efficiency‐enforcement mechanism. A nonparametric programming approach is utilized to construct a measure of overall efficiency that is decomposed into technical and allocative components. Utilizing three inputs and five outputs, measures of efficiency are constructed for a sample of 578 banks from states that permit acquisitions and states that do not. The results indicate that, on average, banks that are subject to takeovers tend to be more efficient Furthermore, the lack of threat of takeovers appears to induce inefficiencies that are technical in nature. The evidence lends support to the hypothesis that the threat of takeovers improves efficiency in firms.
Privatization and economic performance throughout the UK business cycle
Authors: Martin Stephen , Parker David
Published: May 2007

Since 1979, many state‐owned industries in the UK have been sold to private shareholders. Initial studies of the impact of privatization on performance were unable to distinguish once‐and‐for‐all shake‐out effects and those that were part of a continuing process. Moreover, the immediate post‐privatization period often coincided with the boom conditions of the late 1980s. Using two standard performance ratios, this paper examines these issues by tracking the record of eleven firms that were privatized in the 1980s. The results make it difficult to sustain the hypothesis that private ownership is unequivocally more efficient than nationalization.
Computational homogenization for heat conduction in heterogeneous solids
Authors: Özdemir I. , Brekelmans W. A. M. , Geers M. G. D.
Published: May 2007

In this paper, a multi‐scale analysis method for heat transfer in heterogeneous solids is presented. The principles of the method rely on a two‐scale computational homogenization approach which is applied successfully for the stress analysis of multi‐phase solids under purely mechanical loading. The present paper extends this methodology to heat conduction problems. The flexibility of the method permits one to take into account local microstructural heterogeneities and thermal anisotropy, including non‐linearities which might arise at some stage of the thermal loading history. The resulting complex microstructural response is transferred back to the macro level in a consistent manner. A proper macro to micro transition is established in terms of the applied boundary conditions and likewise a micro to macro transition is formulated in the form of consistent averaging relations. Imposition of boundary conditions and extraction of macroscopic quantities are elaborated in detail. A nested finite element solution procedure is outlined, and the effectiveness of the approach is demonstrated by some illustrative example problems. Copyright © 2007 John Wiley & Sons, Ltd.
Role of APAF‐1, E‐cadherin and peritumoural lymphocytic infiltration in tumour budding in colorectal cancer
Authors: Zlobec I , Lugli A , Baker K , Roth S , Minoo P , Hayashi S , Terracciano L , Jass J R
Published: May 2007

Tumour budding or dedifferentiation at the invasive margin of colorectal cancer (CRC) is an important prognostic marker and linked mechanistically to dysregulation of Wnt pathway signalling. Since budding is observed in only 40% of CRCs, we hypothesized that Wnt pathway dysregulation may be a necessary but insufficient explanation for budding and that buds may be destroyed selectively by tumour immune mechanisms. Twenty potential markers of tumour budding were evaluated in tissue microarrays (TMAs) obtained from the main tumour body of 1164 DNA mismatch repair‐proficient CRCs and the findings were correlated with tumour budding, lymphocytic infiltration and survival. Loss of expression of E‐cadherin and APAF‐1 were independent predictors of budding (sensitivity 70.3% and specificity 48.2% when one or the other was lost). Peritumoural lymphocytes (PTLs) were observed more frequently in CRCs with loss of either E‐cadherin or APAF‐1 that were budding‐negative. PTLs and tumour‐infiltrating lymphocytes (TILs) were strongly correlated. The absence of TILs increased the adverse prognostic impact of E‐cadherin and APAF‐1 loss. Co‐occurrence of E‐cadherin loss, APAF‐1 loss and low TIL counts in CRCs was an independent prognostic factor. The findings were verified in whole tissue sections from 88 CRCs with known KRAS mutation status (which was not associated with budding). Loss of E‐cadherin and APAF‐1 within the main body of CRCs are independent predictors of tumour budding. The prognostic benefit of lymphocytic infiltration may be explained by the immune destruction of budding cells. Copyright © 2007 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
Defect structure of ZrO2‐doped rare earth perovskite scintillators
Authors: Stanek C. R. , Levy M. R. , McClellan K. J. , Uberuaga B. P. , Grimes R. W.
Published: May 2007

During the systematic consideration of 4+ cation doping of REAlO3 perovskites for 4+ cations ranging from Ti4+ to Pb4+, a normalization error was discovered in the original Zr4+ solution data that appears in C. R. Stanek et al., phys. stat. sol. (b) 242, R113 (2005). The corrected figure describing solution energetics of Zr4+ in REAlO3 perovskites is provided. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic ordering of Mn and Ru in (La0.52Ba0.48) (Mn0.51Ru0.49)O3
Authors: Wu S. Y. , Li W.‐H. , Yang C. C. , Lynn J. W. , Liu R. S.
Published: May 2007

The cover picture of the current issue relates to the article by S. Y. Wu et al. [1]. The authors study the crystal structure and magnetic properties of a polycrystalline (La0.52Ba0.48) (Mn0.51Ru0.49)O3 sample. The critical temperatures of Ru and Mn were determined using the temperature dependent peak intensities. Neutron magnetic diffraction measurements show anomalies that are associated with the ferromagnetic ordering of the Mn and Mn/Ru spins, respectively, with the spin magnetic moments (shown as arrows) either parallel or at an inclined angle to the c‐axis direction.

The corresponding author Sheng Yun Wu is Assistant Professor at the Department of Physics of the National Dong Hwa University in Hualien, Taiwan. His research interests include the study of magnetic properties in perovskite system and spin polarization of closed d‐shell nanoparticles.
Capture kinetics at deep‐level electron traps in GaN‐based laser diode
Authors: Yastrubchak O. , Wosiński T. , Mąkosa A. , Figielski T. , Porowski S. , Grzegory I. , Czernecki R. , Perlin P.
Published: May 2007

Two deep‐level electron traps, E1 at EC – 0.23 eV and E2 at EC – 0.55 eV, have been revealed by means of deep‐level transient spectroscopy (DLTS) in a GaN‐based laser‐diode heterostructure grown by metalorganic vapour‐phase epitaxy on a bulk GaN substrate. The two traps represent different electron capture behaviours. The E1 trap, which exhibits the logarithmic capture kinetics and the DLTS‐line shape characteristic of band‐like electron states, is attributed to the core states of threading dislocations in a p ‐type layer of the structure. In contrast, the E2 trap, being the most prominent deep‐level electron trap in GaN layers, displays the exponential capture kinetics and is assigned to isolated point defects, likely the nitrogen antisite defect. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theory of partial dislocations in SiC
Authors: Savini G.
Published: May 2007

SiC p‐i‐n diodes exhibit an increase in the voltage drop under forward bias which has been linked with the increased mobility of the partial dislocations. Through first‐principles calculations I have investigated the Shockley partials in 4H‐SiC. I have found that the asymmetric reconstructions do not posses midgap states, while the symmetric reconstructions are always electrically active with a half‐filled band. The kink migration analysis have demonstrated that the symmetric reconstructions are always more likely to migrate. Further I have proposed a new theoretical model that can explain the enhancement of the dislocation mobility under forward bias. This model can be applied to any semiconductor materials in order to predict the behaviour under electron‐hole plasma injections. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Studies on dislocation patterning in 6‐inch GaAs crystals
Authors: Rudolph P. , Frank‐Rotsch Ch. , Juda U. , Eichler St. , Scheffer‐Czygan M.
Published: May 2007

The present paper investigates the correlations between the cell dimension d of characteristic dislocation cell patterns and acting thermo‐elastic stress τ at the growth of 6‐inch semi‐insulating VCz and VGF GaAs crystals. Whereas the dislocation density and cells are analysed experimentally the history of the elastic stress, responsible for the cell formation, is obtained by global numeric calculation. At stresses below 1 MPa diffusion‐controlled creep is the dominant mechanism of dislocation motion. Different d (τ) ‐ proportionalities in VCz and VGF crystals are determined. This is due to the varying thermal conditions and stay times of the growing crystal at high temperatures. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Role of extended defects in brown colouration of diamond
Authors: Hounsome L. S. , Jones R. , Martineau P. M. , Fisher D. , Shaw M. J. , Briddon P. R. , Öberg S.
Published: May 2007

The absorption spectrum of brown diamond is broad and featureless, in both natural type IIa and CVD‐grown material. It is argued that such an absorption is due to an extended, rather than a point, defect. Ab‐initio modelling studies have been conducted on dislocations and extended vacancy‐related defects. While certain dislocations could potentially explain the origin of colour, their density is too low to account for experimentally observed absorption magnitudes. It is demonstrated that a vacancy disk lying in the {111} plane has an absorption spectrum similar to that seen in natural and CVD brown diamond. Such disks are unstable above about 200 vacancies and should relax to dislocation loops in natural diamond. Hydrogen is shown to passivate the optical activity of the disks. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The role of dislocations in producing efficient near‐bandgap luminescence from silicon
Authors: Fraser K. , Stowe D. , Galloway S. , Senkader S. , Falster R. , Wilshaw P.
Published: May 2007

Cathodoluminescence is used to investigate the phenomenon of relatively efficient band‐to‐band luminescence from silicon specimens processed to contain near surface dislocations. Dislocations are produced either by ion implantation and subsequent high‐temperature annealing or by mechanical abrasion of specimens having a wide range of doping concentrations. It is found that the luminescence is not directly related to the presence of dislocations and, in some cases, can be enhanced by low temperature annealing. This luminescence behaviour is explained by the effect of competing non‐radiative recombination due to impurity deep levels and Auger recombination. The enhancement observed in some specimens is due to gettering of the deep level impurities. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Nanoindentation response of compound semiconductors
Authors: Le Bourhis E. , Patriarche G.
Published: May 2007

The paper reviews the nanoindentation behaviour of III‐V semiconductors under concentrated load and its implication for optoelectronic‐device design. We consider first, fundamental aspects involved into the mechanical resistance to contact loading of semiconductor single crystals (elastic‐plastic transition, indentation strain, hardness‐yield relationship). The paper then describes recent applicative studies aimed at improving the heterostructure quality used in optoelectronic applications and emphasizes the so‐called mechanical design (alloying and compliant substructure). (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Luminescence of dislocation network in directly bonded silicon wafers
Authors: Yu X. , Kittler M. , Vyvenko O. F. , Seifert W. , Arguirov T. , Wilhelm T. , Reich M.
Published: May 2007

The luminescence behaviors of dislocation network in directly bonded silicon wafers have been investigated in this paper. The individual dislocations were observed in the sample bonded with extreme small misorientation angles by electron beam induced current (EBIC) technique. The temperature dependence of EBIC contrast of the dislocation lines showed that its contamination degree was smaller than 104/cm. The cathodoluminescence (CL) from the dislocation networks showed D1‐line existed in all the bonded samples, often along with D2‐line. The D3/D4‐lines could also be obtained by tuning the misorientations. Meanwhile, the application of an external bias can effectively enhance the luminescence. Furthermore, a metal‐insulator (SiOx, x < 2)‐semiconductor light‐emitting diode (MOS‐LED) based on the bonded silicon wafer was demonstrated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effects of two‐step rapid thermal processing in different ambients on denuded zone and oxygen precipitation in Czochralski silicon
Authors: Fu Liming , Yang Deren , Ma Xiangyang , Cui Can , Que an. Duanlin
Published: May 2007

The effects of two‐step rapid thermal processing (RTP) sequentially in different ambients on the formation of denuded zone (DZ) and oxygen precipitation in the Czochralski (CZ) silicon wafers have been investigated. With the first‐step RTP in Ar ambient, no obvious DZ but a high density of bulk micro‐defects (BMDs) were formed in the sample with the second‐step RTP in N2 ambient, while the BMD density in the sample with the second‐step RTP in O2 ambient was remarkably low. With the first‐step RTP in N2 ambient, a high density of BMDs and a width of DZ could be formed in either of the samples with the second‐step RTP in Ar or O2 ambient, but the DZ width in the two samples differed to a certain extent. With the first‐step RTP in O2 ambient, the two samples with the second‐step RTP in Ar and N2 ambients respectively possessed reasonably comparable DZ width and BMD density. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structure and energy of partial dislocations in wurtzite‐GaN
Authors: Savini G. , Blumenau A. T. , Heggie M. I. , Öberg S.
Published: May 2007

First‐principle calculations have shown that both the partials can be electrically active. In particular we have shown the Ga(g) core partials are a good candidate for the observed absorption peak at 2.4 eV revealed by energy loss spectroscopy measurements. The symmetric and asymmetric reconstructions have relatively close formation energies. Our results have suggested that the asymmetric reconstructions, characterized by strong bonds along the dislocation line are favourable in intrinsic materials. However, in strongly p and n‐type materials or in high stress field the symmetric reconstructions can become energetically more stable. These reconstructions are always electrically active with a deep band across the forbidden gap. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Peculiarities of dislocation photoluminescence in germanium with quasi‐equilibrium dislocation structure
Authors: Shevchenko S. , Tereshchenko A.
Published: May 2007

The dislocation photoluminescence (DPL) at 4.2 K was studied in germanium (Ge) single crystals of n‐ and p‐type with quasi‐equilibrium structure of 60° dislocations. The DPL spectra for different samples were decomposed on Gaussian lines (Gm‐lines) over the range 0.47‐0.58 eV characterized by practically the same peak energies Em and the widths under 15 meV. The G‐lines with Em ≤ 0.55 eV were ascribed to the radiation of regular segments of 60° dislocations with different stacking fault (SF) widths Δ between 30 and 90° partials. An increase of the dislocations density up to ND ∼ 107 cm–2 was found to result in a considerable growth of the intensity of the G‐lines with Em <0.513 eV. The factors, which promote the appearance of different Δ values for quasi‐equilibrium 60° dislocation structure, are discussed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
X‐ray diffuse scattering from carbon‐ion‐irradiated diamond
Authors: Sugai H. , Maeta H. , Matsumoto N. , Kato T. , Haruna K. , Sataka M. , Ono F.
Published: May 2007

Synthetic single crystal diamonds are irradiated with 100 MeV carbon‐ion and characterized by measurements of the X‐ray lattice parameter and diffuse scattering (XDS) at room temperature. The lattice parameter increases with the ion fluence. The intensity of XDS diffuses asymmetrically to form a streak along the [‐1 0 0] direction parallel to the reciprocal lattice vector. These results suggest that interstitial atoms induced by irradiation aggregate to form dislocation loop on the (1 0 0) plane in the synthetic single crystal diamonds. The results are similar to the XDS of boron‐doped single crystal diamond suggesting that boron atoms are likely to form precipitates on the (1 0 0) plane. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Bound electronic states on a dislocation kink in semiconductors
Authors: Vardanyan Robert A. , Kteyan Armen A.
Published: May 2007

We discuss electron localization on dislocation kinks, that is essential for multiphonon capture of carriers by the dislocation, in view of the problem of recombination‐enhanced defect glide in wide‐band semiconductors. In the case of a smooth kink (when the continuum model is applicable) the formation of bound electronic states is analyzed analytically. The eigenstates and corresponding wave functions are found, depending both on kink parameters and electronic characteristics of the semiconductor. A possible application of the obtained results for the analysis of electron localization on an abrupt kink is considered. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Defect structure in self‐implanted silicon annealed under enhanced hydrostatic pressure – electron microscopy study
Authors: Wzorek M. , Czerwinski A. , Ratajczak J. , Misiuk A. , Surma B. , Kątcki J.
Published: May 2007

The effect of hydrostatic pressure on crystal structure of annealed self‐implanted silicon was investigated by transmission electron microscopy and scanning electron microscopy observation of selectively etched samples. 3°‐angle bevel mechanical polishing allowed determining depth distributions of dislocations. The effect of enhanced hydrostatic pressure on recrystallization and dislocation evolution depending on annealing temperature was discussed. The structure of defects in annealed samples was correlated with photoluminescence spectra on the basis of transmission electron microscopy analysis. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A new method of strain determination in partially relaxed thin films
Authors: Maciejewski G. , Sarzyński M. , Domagala J. Z. , Leszczyński M.
Published: May 2007

It is well known that classical Stoney's formula for radius of thin film bowing fails when thin film is dislocated. Thereby, a method of determination lattice parameters for each of heterostructure epilayers is needed when inelastic relaxation takes place. In this article, we have developed a method of determination lattice parameters of a heterostructure from radius curvature measurement data. Description of deformation when dislocations are nucleated is carefully analyzed. It is shown that in order to take into account nucleated dislocations in thin film an additional term responsible for increased volume of layers should be included in the analysis. The proposed method is based on the finite deformation elasticity and uses the finite element method and bowing radius measurement by the laser beam reflection method. As an example the nitride alloy heterostructure with GaN as a substrate is analyzed. The verification is performed using X‐ray measurement of lattice parameters. A very good correspondence between numerically determined lattice parameters and XRD measurements data are observed. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Stress and unemployment
Authors: Fagin Leonard
Published: May 2007

Although not a new phenomenon, unemployment is now a feature of most industrialized societies. Previous research has highlighted the nature of physical and psychological problems associated with this major life event. Before describing the nature of the response to unemployment, it is essential to analyse why work has become so important for social and psychological adjustment. The response to unemployment can then be described as a predictable set of phases similar to other experiences of loss, such as bereavement. Pathology in unemployment, both physical and psychological, has been observed, and the nature of these disorders is described, as well as those groups more likely to suffer and the possible pathways from health to illness.
Of man and pigs: Is malignant hyperthermia a stress‐related disorder?
Authors: Hall G. M. , Lucke J. N.
Published: May 2007

Malignant hyperthermia (MH) is a very rare but frequently fatal complication of anaesthesia. The identification of susceptible patients depends on a family history of anaesthetic difficulties, increased serum creatine kinase activity and the pharmacological assessment of a muscle biopsy. Dantrolene has been introduced recently as a specific therapeutic agent for MH. Detailed investigation of MH in pigs has drawn attention to the possible role of circulating catecholamines in initiating and potentiating the syndrome. Only certain breeds of pigs develop MH and these breeds are also susceptible to the occurrence of the porcine stress syndrome (PSS) and pale, soft, exudative pork (PSEP). There is increasing evidence that isolated cases of ‘awake MH’ can be triggered by excessive fatigue, emotional stress and high environmental temperatures. It is possible that in some MH‐susceptible families death may occur from ventricular arrhythmias in emotional stressful situations, possibly associated with an underlying cardiomyopathy.
Psychiatric aspects of violence in Northern Ireland
Authors: Cairns Ed , Wilson Ronnie
Published: May 2007

This article reviews a number of studies which have examined the possible impact of political violence on psychiatric morbidity in Northern Ireland. A brief introduction outlining the way in which the violence has varied spatially, quantitatively and qualitatively since 1969 also draws attention to other possible stressors in Northern Irish society. This is followed by a detailed review of studies which have analysed either admission and referral rates, suicide and attempted suicide rates, trends in psychotropic drug prescribing or data from community‐based studies. The criticism is made that several of the early studies did not pay enough attention to important sociodemographic factors and therefore are open to interpretations other than those originally proposed. Nevertheless some agreement does emerge suggesting that it is unlikely that the political violence caused any marked increase in serious psychiatric illnesses but rather stimulated an increase in normal anxiety, particularly among the more vulnerable and especially those with a previous history. Further recent research has begun to suggest that denial of the seriousness of the violence may be one of the mechanisms being used to enable people in Northern Ireland to cope with this continuing problem.