Chaos synchronization in optically programmable logic cells

A possible approach to the synchronization of chaotic circuits is reported. It is based on an Optically Programmable Logic Cell and the signals are fully digital. A method to study the characteristics of the obtained chaos is reported as well as a new technique to compare the obtained chaos from an emitter and a receiver. This technique allows the synchronization of chaotic signals. The signals received at the receiver, composed by the addition of information and chaotic signals, are compared with the chaos generated there and a pure information signal can be detected. Its application to cryptography in Optical Communications comes directly from these properties. The model here presented is based on a computer simulation.

Image processing based on a model of the mammalian retina

A first study in order to construct a simple model of the mammalian retina is reported. The basic elements for this model are Optical Programmable Logic Cells, OPLCs, previously employed as a functional element for Optical Computing. The same type of circuit simulates the five types of neurons present in the retina. Different responses are obtained by modifying either internal or external connections. Two types of behaviors are reported: symmetrical and non-symmetrical with respect to light position. Some other higher functions, as the possibility to differentiate between symmetric and non-symmetric light images, are performed by another simulation of the first layers of the visual cortex. The possibility to apply these models to image processing is reported.

El problema isostático inverso de Vening Meinesz. Teoría y desarrollo. Aplicación práctica para la determinación de la profundidad de la discontinuidad de Mohorovičić en la Península Ibérica

La discontinuidad de Mohorovičić, más conocida simplemente como “Moho” constituye la superficie de separación entre los materiales rocosos menos densos de la corteza y los materiales rocosos más densos del manto, suponiendo estas capas de densidad constante del orden de 2.67 y 3.27 g/cm3, y es un contorno básico para cualquier estudio geofísico de la corteza terrestre. Los estudios sísmicos y gravimétricos realizados demuestran que la profundidad del Moho es del orden de 30-40 km por debajo de la Península Ibérica y 5-15 km bajo las zonas marinas. Además las distintas técnicas existentes muestran gran correlación en los resultados. Haciendo la suposición de que el campo de gravedad de la Península Ibérica (como le ocurre al 90% de la Tierra) está isostáticamente compensado por la variable profundidad del Moho, suponiendo un contraste de densidad constante entre la corteza y el manto y siguiendo el modelo isostático de Vening Meinesz (1931), se formula el problema isostático inverso para obtener tal profundidad a partir de la anomalía Bouguer de la gravedad calculada gracias a la gravedad observada en la superficie terrestre. La particularidad de este modelo es la compensación isostática regional de la que parte la teoría, que se asemeja a la realidad en mayor medida que otros modelos existentes, como el de Airy-Heiskanen, que ha sido históricamente el más utilizado en trabajos semejantes. Además, su solución está relacionada con el campo de gravedad global para toda la Tierra, por lo que los actuales modelos gravitacionales, la mayoría derivados de observaciones satelitales, deberían ser importantes fuentes de información para nuestra solución. El objetivo de esta tesis es el estudio con detalle de este método, desarrollado por Helmut Moritz en 1990, que desde entonces ha tenido poca evolución y seguidores y que nunca se ha puesto en práctica en la Península Ibérica. Después de tratar su teoría, desarrollo y aspectos computacionales, se está en posición de obtener un modelo digital del Moho para esta zona a fin de poder utilizarse para el estudio de la distribución de masas bajo la superficie terrestre. A partir de los datos del Moho obtenidos por métodos alternativos se hará una comparación. La precisión de ninguno de estos métodos es extremadamente alta (+5 km aproximadamente). No obstante, en aquellas zonas donde exista una discrepancia de datos significaría un área descompensada, con posibles movimientos tectónicos o alto grado de riesgo sísmico, lo que le da a este estudio un valor añadido. ABSTRACT The Mohorovičić discontinuity, simply known as “Moho” constitutes the division between the rocky and less thick materials of the mantle and the heavier ones in the crust, assuming densities of the orders of 2.67 y 3.27 g/cm3 respectively. It is also a basic contour for every geophysical kind of studies about the terrestrial crust. The seismic and previous gravimetric observations done in the study area show that the Moho depth is of the order of 30-40 km beneath the ground and 5-15 km under the ocean basin. Besides, the different techniques show a good correlation in their results. Assuming that the Iberian Peninsula gravity field (as it happens for the 90% of the Earth) is isostatically compensated according to the variable Moho depth, supposing a constant density contrast between crust and mantle, and following the isostatic Vening Meinesz model (1931), the inverse isostatic problem can be formulated from Bouguer gravity anomaly data obtained thanks to the observed gravity at the surface of the Earth. The main difference between this model and other existing ones, such as Airy- Heiskanen’s (pure local compensation and mostly used in these kinds of works) is the approaching to a regional isostatic compensation, much more in accordance with reality. Besides, its solution is related to the global gravity field, and the current gravitational models -mostly satellite derived- should be important data sources in such solution. The aim of this thesis is to study with detail this method, developed by Helmut Moritz in 1990, which hardly ever has it put into practice. Moreover, it has never been used in Iberia. After studying its theory, development and computational aspects, we are able to get a Digital Moho Model of the Iberian Peninsula, in order to study the masses distribution beneath the Earth’s surface. With the depth Moho information obtained from alternative methods, a comparison will be done. Both methods give results with the same order of accuracy, which is not quite high (+ 5 km approximately). Nevertheless, the areas in which a higher difference is observed would mean a disturbance of the compensation, which could show an unbalanced area with possible tectonic movements or potential seismic risk. It will give us an important additive value, which could be used in, at first, non related fields, such as density discrepancies or natural disasters contingency plans.

Ethnic diversity as a multilevel construct:the combined effects of dissimilarity, group diversity, and societal status on learning performance in work groups

The authors present a model of the multilevel effects of diversity on individual learning performance in work groups. For ethnically diverse work groups, the model predicts that group diversity elicits either positive or negative effects on individual learning performance, depending on whether a focal individual’s ethnic dissimilarity from other group members is high or low. By further considering the societal status of an individual’s ethnic origin within society (Anglo versus non-Anglo for our U.K. context), the authors hypothesize that the model’s predictions hold more strongly for non-Anglo group members than for Anglo group members. We test this model with data from 412 individuals working on a 24-week business simulation in 87 four- to seven-person groups with varying degrees of ethnic diversity. Two of the three hypotheses derived from the model received full support and one hypothesis received partial support. Implications for theory development, methods, and practice in applied group diversity research are discussed.

Factor analysis and discriminant validity:a brief review of some practical issues

Growth in availability and ability of modern statistical software has resulted in greater numbers of research techniques being applied across the marketing discipline. However, with such advances come concerns that techniques may be misinterpreted by researchers. This issue is critical since misinterpretation could cause erroneous findings. This paper investigates some assumptions regarding: 1) the assessment of discriminant validity; and 2) what confirmatory factor analysis accomplishes. Examples that address these points are presented, and some procedural remedies are suggested based upon the literature. This paper is, therefore, primarily concerned with the development of measurement theory and practice. If advances in theory development are not based upon sound methodological practice, we as researchers could be basing our work upon shaky foundations.

Organizational learning orientation profile and implications for strategic planning capacity

Theory development on the relationship between strategic planning and organizational performance has focussed on largely discrete examinations of dependent and independent variables. While the literature has examined the impact of organizational learning on strategic planning, no holistic empirical approaches have been employed in order to fully explore the inter-play between these important constructs. This paper addresses the cited limitations in both the strategic planning and organizational performance literatures by creating profiles of organizational learning and strategic planning capacity using a configuration theory-based approach. The organizational learning orientation profiles (OLOPs) created of prospector, disseminator, interpretative and memory, contribute to theory development regarding the relationship of strategic planning and organizational learning. The theory developed provides insights that have not been previously reported.

Problems with formative and higher-order reflective variables

Cadogan and Lee (this issue) discuss the problems inherent in modeling formative latent variables as endogenous. In response to the commentaries by Rigdon (this issue) and Finn and Wang (this issue), the present article extends the discussion on formative measures. First, the article shows that regardless of whether statistical identification is achieved, researchers are unable to illuminate the nature of a formative latent variable. Second, the study clarifies issues regarding formative indicator weighting, highlighting that the weightings of formative components should be specified as part of the construct definition. Finally, the study shows that higher-order reflective constructs are invalid, highlights the damage their use can inflict on theory development and knowledge accumulation, and provides recommendations on a number of alternative models which should be used in their place (including the formative model). © 2012 Elsevier Inc.

Model evaluation and case series data

We discuss aggregation of data from neuropsychological patients and the process of evaluating models using data from a series of patients. We argue that aggregation can be misleading but not aggregating can also result in information loss. The basis for combining data needs to be theoretically defined, and the particular method of aggregation depends on the theoretical question and characteristics of the data. We present examples, often drawn from our own research, to illustrate these points. We also argue that statistical models and formal methods of model selection are a useful way to test theoretical accounts using data from several patients in multiple-case studies or case series. Statistical models can often measure fit in a way that explicitly captures what a theory allows; the parameter values that result from model fitting often measure theoretically important dimensions and can lead to more constrained theories or new predictions; and model selection allows the strength of evidence for models to be quantified without forcing this into the artificial binary choice that characterizes hypothesis testing methods. Methods that aggregate and then formally model patient data, however, are not automatically preferred to other methods. Which method is preferred depends on the question to be addressed, characteristics of the data, and practical issues like availability of suitable patients, but case series, multiple-case studies, single-case studies, statistical models, and process models should be complementary methods when guided by theory development.

Improper use of formative endogenous variables

Researchers often develop and test conceptual models containing formative variables. In many cases, these formative variables are specified as being endogenous. This article provides a clarification of formative variable theory, distinguishing between the formative latent variable and the formative composite variable. When an endogenous latent variable relies on formative indicators for measurement, empirical studies can say nothing about the relationship between exogenous variables and the endogenous formative latent variable: conclusions can only be drawn regarding the exogenous variables' relationships with a composite variable. The authors also show the dangers associated with developing theory about antecedents to endogenous formative variables at the (aggregate) formative latent variable level. Modeling relationships with endogenous formative variables at the (disaggregate) indicator level informs richer theory development, and encourages more precise empirical testing. When antecedents' relationships with endogenous formative variables are modeled at the formative latent variable level rather than the formative indicator level, theory construction can verge on the superficial, and empirical findings can be ambiguous in substantive meaning.

Control of electronic channel affiliates:an exploratory study and research propositions

Electronic channel affiliates are important online intermediaries between customers and host retailers. However, no work has studied how online retailers control online intermediaries. By conducting an exploratory content analysis of 85 online contracts between online retailers and their online intermediaries, and categorizing the governing mechanisms used, insights into the unique aspects of the control of online intermediaries are presented. Findings regarding incentives, monitoring, and enforcement are presented. Additionally, testable research propositions are presented to guide further theory development, drawing on contract theory, resource dependence theory and agency theory. Managerial implications are discussed. © 2012 Elsevier Inc.

Internet technologies, ECRM capabilities, and performance benefits for SMEs:An exploratory study

Research on large firms suggests that dedicated customer relationship management (CRM) software applications play a critical role in creating and sustaining customer relationships. CRM is also of strategic importance to small and medium-sized enterprises (SMEs), but most of them do not employ dedicated CRM software. Instead they use generic Internet-based technologies to manage customer relationships with electronic CRM (eCRM). There has been little research on the extent to which the use of generic Internet technologies contributes to SME performance. The present study fills the gap, building upon the literature on organizational capabilities, marketing, and SMEs to develop a research model with which to explore the relationships between generic Internet technologies, eCRM capabilities, and the resulting performance benefits in the SME context. A survey across 286 SMEs in Ireland finds strong empirical evidence in support of the hypotheses regarding these benefits. The study contributes to managerial decision making by showing how SMEs can use generic Internet technologies to advance their customer relationships and contributes to theory development by conceptualizing eCRM capabilities in an SME context.

The influence of context on the strategic decision-making process:a review of the literature

This paper critically reviews the strategic decision-making process literature, with a specific focus on the effects of context. Context refers to the top management team, strategic decision-specific characteristics, the external environment and firm characteristics. This literature review also develops an illustrative framework that incorporates these four different categories of contextual variables that influence the strategic decision-making process. As a result of the variety and pervasiveness of contextual variables featured within the literature, a comprehensive and up-to-date review is essential for organizing and synthesizing the extant literature to explicate an agenda for future research. The purpose of this literature review is threefold: first, to critically review the strategic decision-making process literature to highlight the underlying themes, issues, tensions and debates in the field; second, to identify the opportunities for future theory development; and third, to state the methodological implications arising from this review. © 2013 British Academy of Management and John Wiley & Sons Ltd.

The discretionary role of the line manager in inspiring work engagement and innovative behaviour:a study of social exchange and job resources in the public sector

This thesis is about the discretionary role of the line manager in inspiring the work engagement of staff and their resulting innovative behaviour examined through the lens of Social Exchange Theory (Blau, 1964) and the Job Demands-Resources theory (Bakker, Demerouti, Nachreiner & Schaufeli, 2001). The study is focused on a large British Public Sector organisation undergoing a major organisational shift in the way in which they operate as part of the public sector. It is often claimed that people do not leave organisations; they leave line managers (Kozlowski & Doherty, 1989). Regardless of the knowledge in the literature concerning the importance of the line manager in organisations (Purcell, 2003), the engagement literature in particular is lacking in the consideration of such a fundamental figure in organisational life. Further, the understanding of the black box of managerial discretion and its relationship to employee and organisation related outcomes would benefit from greater exploration (Purcell, 2003; Gerhart, 2005; Scott, et al, 2009). The purpose of this research is to address these gaps with relation to the innovative behaviour of employees in the public sector – an area that is not typically associated with the public sector (Bhatta, 2003; McGuire, Stoner & Mylona, 2008; Hughes, Moore & Kataria, 2011). The study is a CASE Award PhD thesis, requiring academic and practical elements to the research. The study is of one case organisation, focusing on one service characterised by a high level of adoption of Strategic Human Resource Management activities and operating in a rather unique manner for the public sector, having private sector competition for work. The study involved a mixed methods approach to data collection. Preliminary focus groups with 45 participants were conducted, followed by an ethnographic period of five months embedded into the service conducting interviews and observations. This culminated in a quantitative survey delivered within the wider directorate to approximately 500 staff members. The study used aspects of the Grounded Theory (Glaser & Strauss, 1967) approach to analyse the data and developed results that highlight the importance of the line manager in an area characterised by SHRM and organisational change for engaging employees and encouraging innovative behaviour. This survey was completed on behalf of the organisation and the findings of this are presented in appendix 1, in order to keep the focus of the PhD on theory development. Implications for theory and practice are discussed alongside the core finding. Line managers’ discretion surrounding the provision of job resources (in particular trust, autonomy and implementation and interpretation of combined bundles of SHRM policies and procedures) influenced the exchange process by which employees responded with work engagement and innovative behaviour. Limitations to the research are the limitations commonly attributed to cross-sectional data collection methods and those surrounding generalisability of the qualitative findings outside of the contextual factors characterising the service area. Suggestions for future research involve addressing these limitations and further exploration of the discretionary role with regards to extending our understanding of line manager discretion.

Strategic marketing and e-business

The dramatic growth in e-business is manifest in phenomena such as the surge in internet retailing, the boom in social media based marketing communications, and the centrality of e-commerce to many organizations’ core strategies. Despite this the precise implications of e-business for marketing strategy remain little-understood. In order to guide theory development and practice in the marketing strategy domain, it is of fundamental importance to take stock of the impact that e-business has had upon strategic marketing. Therefore, this chapter develops a conceptual framework in order to explicate the implications of e-business for strategic marketing theory and practice. We find that the impact of e-business on strategic marketing is far-reaching; influencing not only isolated departments, but the organization as a whole. Finally, we conclude that whilst organizations should be alert to the dynamic opportunities and threats posed by e-business, the guiding principle of value creation should not be forgotten.

An empirical examination of the strategic decision-making process:the relationship between context, process, and outcomes

Despite concerted academic interest in the strategic decision-making process (SDMP) since the 1980s, a coherent body of theory capable of guiding practice has not materialised. This is because many prior studies focus only on a single process characteristic, often rationality or comprehensiveness, and have paid insufficient attention to context. To further develop theory, research is required which examines: (i) the influence of context from multiple theoretical perspectives (e.g. upper echelons, environmental determinism); (ii) different process characteristics from both synoptic formal (e.g. rationality) and political incremental (e.g. politics) perspectives, and; (iii) the effects of context and process characteristics on a range of SDMP outcomes. Using data from 30 interviews and 357 questionnaires, this thesis addresses several opportunities for theory development by testing an integrative model which incorporates: (i) five SDMP characteristics representing both synoptic formal (procedural rationality, comprehensiveness, and behavioural integration) and political incremental (intuition, and political behaviour) perspectives; (ii) four SDMP outcome variables—strategic decision (SD) quality, implementation success, commitment, and SD speed, and; (iii) contextual variables from the four theoretical perspectives—upper echelons, SD-specific characteristics, environmental determinism, and firm characteristics. The present study makes several substantial and original contributions to knowledge. First, it provides empirical evidence of the contextual boundary conditions under which intuition and political behaviour positively influence SDMP outcomes. Second, it establishes the predominance of the upper echelons perspective; with TMT variables explaining significantly more variance in SDMP characteristics than SD specific characteristics, the external environment, and firm characteristics. A newly developed measure of top management team expertise also demonstrates highly significant direct and indirect effects on the SDMP. Finally, it is evident that SDMP characteristics and contextual variables influence a number of SDMP outcomes, not just overall SD quality, but also implementation success, commitment, and SD speed.