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Selected AbstractsA decentralized and fault-tolerant Desktop Grid system for distributed applications,CONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 3 2010Heithem Abbes Abstract This paper proposes a decentralized and fault-tolerant software system for the purpose of managing Desktop Grid resources. Its main design principle is to eliminate the need for a centralized server, therefore to remove the single point of failure and bottleneck of existing Desktop Grids. Instead, each node can play alternatively the role of client or server. Our main contribution is to design the PastryGrid protocol (based on Pastry) for Desktop Grid in order to support a wider class of applications, especially the distributed application with precedence between tasks. Compared with a centralized system, we evaluate our approach over 205 machines executing 2500 tasks. The results we obtain show that our decentralized system outperforms XtremWeb-CH which is configured as a master/slave, with respect to the turnaround time. Copyright © 2009 John Wiley & Sons, Ltd. [source] Great northern researchers: discoverers of the earliest Palaeozoic vertebratesACTA ZOOLOGICA, Issue 2009Hans-Peter Schultze Abstract The lives and works of Dr Elga Mark-Kurik and Dr Valentina Karatajute-Talimaa, Estonian and Lithuanian palaeontologists, respectively, are presented as part of their celebration at the 11th Symposium on Early/Lower Vertebrates at Uppsala. Both graduated from the university of their home town, Tartu and Vilnius, respectively. Elga became a Researcher at the Institute of Geology of the Estonian S.S.R. Academy of Sciences, in Tallinn, whereas Valentina worked for the Institute of Geology, Vilnius. Both were mentored by D. V. Obruchev of Moscow. Elga chose placoderms and psammosteid heterostracans as main research objects. Valentina also began with whole fish, antiarch placoderms, but then chose fish microfossils with W. Gross as mentor and discovered the oldest chondrichthyans. Both work as palaeobiologists understanding the implications of their fossils for functional interpretation and palaeogeography; their main contribution is in biostratigraphy (over 50% of their publications). In 1976 Elga organized the 1st Middle Palaeozoic Fossil Fish Symposium in Tallinn. The co-operation of young eastern and western palaeoichthyologists begun there culminating in the 1990s with the international research effort of the UNESCO-IUGS International Geological Correlation Programmes (328, 406 and 491). [source] Assessment of the benefits of user involvement in health research from the Warwick Diabetes Care Research User Group: a qualitative case studyHEALTH EXPECTATIONS, Issue 3 2007Antje Lindenmeyer PhD Abstract Objective, To assess the benefits of involving health-care users in diabetes research. Design and participants, For this qualitative case study, semi-structured interviews were conducted with researchers who had worked extensively with the group. During regular meetings of the Research User Group, members discussed their views of the group's effectiveness as part of the meeting's agenda. Interviews and discussions were transcribed, coded using N-Vivo software and analysed using constant comparative methods. Results, Involvement of users in research was generally seen as contributing to effective and meaningful research. However, the group should not be considered to be representative of the patient population or participants of future trials. An important contributor to the group's success was its longstanding nature, enabling users to gain more insight into research and form constructive working relationships with researchers. The user-led nature of the group asserted itself, especially, in the language used during group meetings. A partial shift of power from researchers to users was generally acknowledged. Users' main contribution was their practical expertise in living with diabetes, but their involvement also helped researchers to remain connected to the ,real world' in which research would be applied. While the group's work fulfilled established principles of consumer involvement in research, important contributions relying on personal interaction between users and researchers were hard to evaluate by process measures alone. Conclusions, We demonstrated the feasibility, acceptability and effectiveness of this longstanding, experienced, lay-led research advisory group. Its impact on research stems from the continuing interaction between researchers and users, and the general ethos of learning from each other in an on-going process. Both process measures and qualitative interviews with stakeholders are needed to evaluate the contributions of service users to health research. [source] On parameter estimation for excitation control of synchronous generatorsINTERNATIONAL JOURNAL OF ADAPTIVE CONTROL AND SIGNAL PROCESSING, Issue 5 2004Martha Galaz Abstract This paper deals with the problem of identification of the network parameters and the desired equilibrium in applications of excitation control for synchronous generators. Our main contribution is the construction of a new non-linear identifier that provides asymptotically consistent estimates (with guaranteed transient bounds) of the line impedance and the equilibrium for the classical three-dimensional flux-decay model of a single generator connected to an infinite bus. This model is non-linear, and non-linearly parameterized, and the equilibria depend also non-linearly on the unknown parameters. The proposed estimator can be used, adopting a certainty equivalent approach, to make adaptive any power system stabilizer that relies on the knowledge of these parameters. The behaviour of the scheme is illustrated in two simulated case studies with the interconnection and damping assignment passivity-based controller recently proposed by the authors. Copyright © 2004 John Wiley & Sons, Ltd. [source] Performance analysis of system with L-branch selection combining over correlated Weibull fading channels in the presence of cochannel interferenceINTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS, Issue 2 2010. Stefanovi, Mihajlo Abstract In this paper, the performance of L-branch selection combining receiver over correlated Weibull fading channels in the presence of correlated Weibull-distributed cochannel interference is analyzed. Closed-form expressions for probability density function and cumulative distribution function of the signal-to-interference ratio at the output of the selection combining receiver present main contribution of this paper. Numerical results are also presented to show the effects of various parameters as the fading severity, correlation and number of branches on outage probability. Copyright © 2009 John Wiley & Sons, Ltd. [source] Experimental study on sulfur trioxide decomposition in a volumetric solar receiver,reactorINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 9 2009Adam Noglik Abstract Process conditions for the direct solar decomposition of sulfur trioxide have been investigated and optimized by using a receiver,reactor in a solar furnace. This decomposition reaction is a key step to couple concentrated solar radiation or solar high-temperature heat into promising sulfur-based thermochemical cycles for solar production of hydrogen from water. After proof-of-principle a modified design of the reactor was applied. A separated chamber for the evaporation of the sulfuric acid, which is the precursor of sulfur trioxide in the mentioned thermochemical cycles, a higher mass flow of reactants, an independent control and optimization of the decomposition reactor were possible. Higher mass flows of the reactants improve the reactor efficiency because energy losses are almost independent of the mass flow due to the predominant contribution of re-radiation losses. The influence of absorber temperature, mass flow, reactant initial concentration, acid concentration, and residence time on sulfur trioxide conversion and reactor efficiency has been investigated systematically. The experimental investigation was accompanied by energy balancing of the reactor for typical operational points. The absorber temperature turned out to be the most important parameter with respect to both conversion and efficiency. When the reactor was applied for solar sulfur trioxide decomposition only, reactor efficiencies of up to 40% were achieved at average absorber temperature well below 1000°C. High conversions almost up to the maximum achievable conversion determined by thermodynamic equilibrium were achieved. As the re-radiation of the absorber is the main contribution to energy losses of the reactor, a cavity design is predicted to be the preferable way to further raise the efficiency. Copyright © 2009 John Wiley & Sons, Ltd. [source] A novel fault management approach for DWDM optical networksINTERNATIONAL JOURNAL OF NETWORK MANAGEMENT, Issue 5 2006W. Fawaz Connection availability is considered as a critical metric when providing differentiated services in Wavelength-Division Multiplexing mesh networks. Indeed, one of the major concerns of optical network operators is related to improving the availability of services provided to their highest-class clients. Achieving this objective is possible through managing faults using the different classical protection schemes, namely the so-called dedicated and shared protection schemes. However, the majority of the work concerning protection schemes has considered the primary connections as equally important when contending for the use of the backup resources. As a main contribution in this paper, we therefore propose an improvement of the existing protection schemes through the introduction of relative priorities among the different primary connections contending for the access to the protection path. To evaluate numerically the benefits of the service differentiation feature introduced in our proposal, we first develop a mathematical model, based on which we derive explicit expressions for the average connection availabilities that result from both the classical protection schemes and the proposed priority-aware one. Through this model, we show how the availability of the highest-class clients is improved when deploying the proposed priority-aware protection scheme. Finally, with the same objective in mind, we develop a simulation study, where a given set of connection demands with predefined availability requirements is provisioned using different protection strategies. Through this study, we show that the priority-aware protection strategy satisfies service-availability requirements in a cost-effective manner compared with the classical protection schemes.Copyright © 2006 John Wiley & Sons, Ltd. [source] Symplectic molecular dynamics integration using normal mode analysisINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2001anka Jane Abstract The split integration symplectic method (SISM) for molecular dynamics (MD) integration using normal mode analysis based on a factorization of the Liouville propagator is presented. This approach is quite distinct from others that use fractional-step methods, owing to the analytical treatment of high-frequency motions. The method involves splitting the total Hamiltonian of the system into a harmonic part and the remaining part. Then the Hamilton equations are solved using a second-order generalized leapfrog integration scheme in which the purely harmonic Hamiltonian (which represents the main contribution of the chemical bonds and angles) is treated analytically, i.e., independent of the step size of integration, by a normal mode analysis that is carried out only once, at the beginning of calculation. The whole integration step combines analytical evolution of the harmonic part of the Hamiltonian with a correction arising from the remaining part. The proposed algorithm requires only one force evaluation per integration step. The algorithm was tested on a simple system of linear chain molecules. Results demonstrate the method makes possible the integration of the MD equations over larger time steps without loss of stability while being economical in computer time. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 84: 2,12, 2001 [source] A THEORETICAL AND PRACTICAL PERSPECTIVE ON THE EQUITY RISK PREMIUM,JOURNAL OF ECONOMIC SURVEYS, Issue 2 2008Roelof SalomonsArticle first published online: 10 MAR 200 Abstract In historical perspective, equity returns have been higher than interest rates but have also varied a good deal more. However, the average excess return has been larger than what could be expected based on classical equilibrium theory: the equity risk premium (ERP) puzzle. This paper has two objectives. First, the paper presents a comprehensive overview of the vast literature developed aimed at adjusting theory and testing the robustness of the puzzle. Here we will show that the failure of theory to link asset prices to economics is mostly quantitative by nature and not qualitative (anymore). Second, beyond providing a survey of theory, we aim for a relevant practical angle as well. Our main contribution is that we spend time on why returns have been higher than investors reasonably could have expected. We present evidence that forecasts of equity returns can be enhanced by valuation models: low valuation levels (low price-to-earnings ratios) portend high subsequent returns. While conventional wisdom (several years ago) was to use historical returns to forecast future returns, a growing consensus now recognizes that the predictive power of valuation ratios is preferred. Finally we provide some practical implications based on this predictability. While the ERP is essentially a long-term issue, the likelihood of a lower risk premium increases risk for many and means that short-term volatility might not be neglected. [source] Range error detection caused by occlusion in non-coaxial LADARs for scene interpretationJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 10 2005Bingbing Liu When processing laser detection and ranging (LADAR) sensor data for scene interpretation, for example, for the purposes of feature extraction and/or data association in mobile robotics, most previous work models such devices as processing range data which follows a normal distribution. In this paper, it is demonstrated that commonly used LADARs suffer from incorrect range readings at changes in surface reflectivity and/or range discontinuities, which can have a much more detrimental effect on such algorithms than random noise. Most LADARs fall into two categories: coaxial and separated transmitter and receiver configurations. The latter offer the advantage that optical crosstalk is eliminated, since it can be guaranteed that all of the transmitted light leaves the LADAR and is not in any way partially reflected within it due to the beam-splitting techniques necessary in coaxial LADARs. However, they can introduce a significant disparity effect, as the reflected laser energy from the target can be partially occluded from the receiver. As well as demonstrating that false range values can result due to this occlusion effect from scanned LADARs, the main contribution of this paper is that the occurrence of these values can be reliably predicted by monitoring the received signal strength and a quantity we refer to as the "transceiver separation angle" of the rotating mirror. This paper will demonstrate that a correct understanding of such systematic errors is essential for the correct further processing of the data. A useful design criterion for the optical separation of the receiver and transmitter is also derived for noncoaxial LADARs, based on the minimum detectable signal amplitude of a LADAR and environmental edge constraints. By investigating the effects of various sensor and environmental parameters on occlusion, some advice is given on how to make use of noncoaxial LADARs correctly so as to avoid range errors when scanning environmental discontinuities. © 2005 Wiley Periodicals, Inc. [source] A Flexible Software Architecture for Hybrid TrackingJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 2 2004Miguel Ribo Fusion of vision-based and inertial pose estimation has many high-potential applications in navigation, robotics, and augmented reality. Our research aims at the development of a fully mobile, completely self-contained tracking system, that is able to estimate sensor motion from known 3D scene structure. This requires a highly modular and scalable software architecture for algorithm design and testing. As the main contribution of this paper, we discuss the design of our hybrid tracker and emphasize important features: scalability, code reusability, and testing facilities. In addition, we present a mobile augmented reality application, and several first experiments with a fully mobile vision-inertial sensor head. Our hybrid tracking system is not only capable of real-time performance, but can also be used for offline analysis of tracker performance, comparison with ground truth, and evaluation of several pose estimation and information fusion algorithms. © 2004 Wiley Periodicals, Inc. [source] The Influence of a Structurationist View on Strategic Management Research*JOURNAL OF MANAGEMENT STUDIES, Issue 2 2004Marlei Pozzebon ABSTRACT In this article, strategic management research using structuration theory from 1995 to 2000 is reviewed. I describe and analyse the theoretical articulations adopted to make sense of strategy using a structurationist view. I found that, instead of being applied as the sole theoretical foundation, Giddens' propositions have been incorporated into other perspectives, the effects of which should be known by researchers looking for theoretical frameworks that avoid dichotomist thinking. The paper draws on the effects that structurationist arguments may produce regarding classical oppositions such as micro/macro and voluntarist/determinist. Its main contribution is to show how theoretical complementarities using structuration theory are promising avenues of research in the strategic management field. It also suggests that, although other alternatives of avoiding dichotomist logic exist, making a choice among them is more a question of ontological affinity than of making the ,better choice' among competing accounts. There are several routes to advance the understanding of the possibilities of human choice. [source] Towards a specific characterisation of components on a cell surface,combined TERS-investigations of lipids and human cellsJOURNAL OF RAMAN SPECTROSCOPY, Issue 10 2009R. Böhme Abstract Supported lipid structures and human cells (human dermal derived keratinocyte, HaCaT) were investigated using tip-enhanced Raman spectroscopy (TERS) to use the high spatial resolution capabilities of TERS, which is assumed to be less than 10 nm, to determine specific components on the cell surface. As lipids are a main component of cellular membranes, the correlation of spectral properties of pure lipids with respect to the complex biological sample was investigated. Induced by dynamic structural changes as well as nanoscale effects, a particular spectral feature of the lipid TERS spectra is found to vary, and a similar spectral deviation appears among the TERS spectra measured on the cell. Modifications of the cell surface alone cannot cause such behaviour. In contrast to soft lipid agglomerates, the cells were fixed and therefore hampered for intrinsic structural changes. Hence, the main contribution for the cell TERS spectra variation results from nanoscale effects, determined by different spectral characteristics compared to conventional Raman spectroscopy. The present results demonstrate the capability of TERS to provide a detailed and fast insight into the composition of the cell surface, even allowing the detection of single components. Copyright © 2009 John Wiley & Sons, Ltd. [source] Latitudinal and longitudinal process diversityJOURNAL OF SOFTWARE MAINTENANCE AND EVOLUTION: RESEARCH AND PRACTICE, Issue 1 2003Nils T Siebel Abstract Software processes vary across organizations and over time. Managing this process diversity is a delicate balancing act between creative, healthy diversity and chaos. In this paper, we examine a particular aspect of this issue, namely some relationships between diversity in software processes, software evolution and the quality of software products and processes. Our main contribution is to distinguish between two broad kinds of process diversity, which we call latitudinal and longitudinal process diversity. To illustrate the differences between these two, we examine the case of a medium-sized system (50,000 lines of C++ code) which has undergone major changes during its lifetime of 10 years. The software was originally developed by an individual academic using a research-oriented process to develop a standalone proof-of-concept system. In a current multi-team project, involving three industrial and three academic partners, the software has been adapted for integration as a subsystem of a near-market product. We suggest ways in which the observed process diversity seems to be linked to a change in the software's propensity for evolution, and we discuss the impact of this on both product and process quality. Copyright © 2003 John Wiley & Sons, Ltd. [source] Electrical and optical low frequency noises in multimodal vertical cavity surface emitting lasersLASER PHYSICS LETTERS, Issue 10 2006F. Principato Abstract Experimental investigations of the low frequency noise of multimode 780 nm vertical cavity surface emitting lasers are reported. Electrical noise, optical noise and their correlation have been measured in the frequency range 1 Hz,95 kHz. The results show that the main contribution to the electrical noise is located in the distributed Bragg reflector layers of the laser. The optical power and pump current noise sources are strongly correlated below and around the threshold, while are weakly correlated above threshold. It is argued that the noise in the optical power is due to both free injection carrier noise and optical gain fluctuations. (© 2006 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Modification of impact craters in the northern plains of Mars: Implications for Amazonian climate historyMETEORITICS & PLANETARY SCIENCE, Issue 10 2006M. A. Kreslavsky Two of the 130 craters have unusually rough ejecta; they are deep, have steep walls, and are apparently the youngest in the population. Icy mantles filling the local subkilometer-scale topographic lows is the main contribution to ejecta smoothing, which occurs at a time scale on the order of tens of Myr. Wall degradation and crater shallowing generally occur at longer time scales, comparable to the duration of the Amazonian period. Many craters are shallow due to filling of the crater with specific ice-rich material of uncertain origin. We use our collected data to infer the nature of the past climate back through the Amazonian, a period prior to ,10,20 Myr ago, when orbital parameter solutions are chaotic and one must rely on geological data to infer climate conditions. We conclude that moderately high obliquity and wide obliquity variations were probable during the last 40,160 Myr. We tentatively conclude that high obliquity peaks (>40,45°) may have occurred episodically through the last 210,430 Myr. A sharp step in the frequency distribution of wall steepness at 20° may indicate a geologically long period prior to that time where obliquity never exceeded 40,45°. [source] Risk-sensitive sizing of responsive facilitiesNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 3 2008Sergio Chayet Abstract We develop a risk-sensitive strategic facility sizing model that makes use of readily obtainable data and addresses both capacity and responsiveness considerations. We focus on facilities whose original size cannot be adjusted over time and limits the total production equipment they can hold, which is added sequentially during a finite planning horizon. The model is parsimonious by design for compatibility with the nature of available data during early planning stages. We model demand via a univariate random variable with arbitrary forecast profiles for equipment expansion, and assume the supporting equipment additions are continuous and decided ex-post. Under constant absolute risk aversion, operating profits are the closed-form solution to a nontrivial linear program, thus characterizing the sizing decision via a single first-order condition. This solution has several desired features, including the optimal facility size being eventually decreasing in forecast uncertainty and decreasing in risk aversion, as well as being generally robust to demand forecast uncertainty and cost errors. We provide structural results and show that ignoring risk considerations can lead to poor facility sizing decisions that deteriorate with increased forecast uncertainty. Existing models ignore risk considerations and assume the facility size can be adjusted over time, effectively shortening the planning horizon. Our main contribution is in addressing the problem that arises when that assumption is relaxed and, as a result, risk sensitivity and the challenges introduced by longer planning horizons and higher uncertainty must be considered. Finally, we derive accurate spreadsheet-implementable approximations to the optimal solution, which make this model a practical capacity planning tool.© 2008 Wiley Periodicals, Inc. Naval Research Logistics, 2008 [source] Deterministic radio broadcasting at low cost ,NETWORKS: AN INTERNATIONAL JOURNAL, Issue 2 2002Anders Dessmark Abstract We consider distributed deterministic broadcasting in synchronous radio networks. A node receives a message in a given round if and only if exactly one of its neighbors transmits. The source message has to reach all nodes. We assume that nodes do not know the network topology or even their immediate neighborhood. (Such networks are called ad hoc.) We are concerned with two efficiency measures of broadcasting algorithms: their execution time (number of rounds) and their cost (number of transmissions). We focus our study on the execution time of algorithms which have cost close to minimum. We consider two scenarios depending on whether nodes know or do not know global parameters of the network: the number n of nodes and the eccentricity D of the source. Our main contribution is proving tight lower bounds on the time of low-cost broadcasting which show sharp differences between these scenarios. In each case, we also give broadcasting algorithms whose performance matches these lower bounds. © 2002 Wiley Periodicals, Inc. [source] Arthur Farquhar on Economic Delusions: An Examination of the Case for ProtectionAMERICAN JOURNAL OF ECONOMICS AND SOCIOLOGY, Issue 3 2010Article first published online: 24 JUN 2010, Thomas L. Martin Arthur Farquhar (1838,1929) was a successful manufacturer and exporter of mechanical steel farming implements who also took the time to participate in the day's free trade versus protectionism debate. His main contribution to the national tariff debate was the 1891 book Economic and Industrial Delusions: A Discussion of the Case for Protection. The book was written as a direct response to the McKinley Tariff of 1890 and is very much a polemic against the tariff by a disappointed former Republican. This article summarizes his economic analysis of the incidence of the tariff, the relationship between trade competitiveness and relative wages, and the tariff's effect on overall economic development. [source] Creation of excitations and defects in insulating materials by high-current-density electron beams of nanosecond pulse durationPHYSICA STATUS SOLIDI (C) - CURRENT TOPICS IN SOLID STATE PHYSICS, Issue 1 2005D. I. Vaisburd Abstract The paper is concerned with fast and ultra-fast processes in insulating materials under the irradiation by a high-current-density electron beam of a nanosecond pulse duration. The inflation process induced by the interaction of a high-intensity electron beam with a dielectric is examined. The "instantaneous" distribution of non-ionizing electrons and holes is one of the most important stages of the process. Ionization-passive electrons and holes make the main contribution to many fast processes with a characteristic time in the range 10,14 ÷ 10,12 s: high-energy conductivity, intraband luminescence, etc. A technique was developed for calculation of the "instantaneous" distribution of non-ionizing electrons and holes in a dielectric prior to electron-phonon relaxation. The following experimental effects are considered: intraband luminescence, coexistence of intraband electron luminescence and band-to-band hole luminescence in CsI, high energy conductivity; generation of mechanical fields and their interaction with cracks and dislocations. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Effect of high-energy vibro-milling of filler on the mechanical properties of filled high-density polyethylenePOLYMER COMPOSITES, Issue 3 2003Shaoyun Guo The effect of high-energy mechanical milling of CaCO3 (calcium carbonate) and STC (a mixture of sericite, tridymite and cristobalite) on mechanical properties, rheological and dynamical mechanical behavior of high-density polyethylene (HDPE)/CaCO3 and HDPE/STC was studied through SEM (scanning electron microscope), DMTA (dynastic mechanical test analysis), mechanical and melt rheological properties tests. The experimental results show that addition of fillers treated by coupling agent and vibromilling to HDPE makes the impact strength of HDPE greatly increased. The impact strength of HDPE/treated CaCO3 (60/40) and HDPE/treated STC (60/40) is ca. 4 and 3 times respectively as high as that of HDPE. The SEM micrographs of impact fractured surfaces of treated fillers filled HDPE show extensive plastic deformation of HDPE matrix, indicating that the plastic deformation of matrix induced by the treated fillers is the main contribution for absorbing a great amount of impact energy. This is the reason why the impact strength of HDPE greatly increases with addition of coupling agent and vibromilling treated fillers. The intensity of , relaxation peak of HDPE in HDPE/treated CaCO3 on tan, vs. temperature curve increases and the peak shifts to higher temperature due to its stronger interface interaction as compared with that of HDPE/untreated CaCO3. [source] Do futures-based strategies enhance dynamic portfolio insurance?THE JOURNAL OF FUTURES MARKETS, Issue 6 2004Binh Huu Do In this paper we investigate the relative performance of two approaches to dynamic portfolio insurance: the synthetic put and the Constant Proportion Portfolio Insurance (CPPI). The investigation is conducted on the Australian market, over a sample period of 59 non-overlapping quarters from December 1987 to December 2002. Its main contribution is to provide a comprehensive assessment of the two approaches under different market conditions, and the testing of ex ante information as an input into the trading program. The major finding is that the futures-based implementation of both synthetic put and the CPPI approach is robust to both tranquil and turbulent market conditions in preserving the desired floor. The fact that this conclusion includes the case of employing implied volatility (obtained from the options market) is highly encouraging as it suggests high implementability of the strategy. Notably, the risk-return tradeoff shows that portfolio insurance using this volatility measure yields a return that is 64 basis points over the risk free investment. © 2004 Wiley Periodicals, Inc. Jrl Fut Mark 24:591,608, 2004 [source] Thermodynamic and spectroscopic study of the binding of dimethyltin(IV) by citrate at 25 °CAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 7 2006Paola Cardiano Abstract Thermodynamic (potentiometric and calorimetric) and spectroscopic (1H NMR, 119Sn Mössbauer) studies were performed in aqueous solution in order to characterize the interaction of dimethyltin(IV) cation with citrate ligand. Six species {(CH3)2Sn(cit),; [(CH3)2Sn]2(cit)22,; (CH3)2Sn(cit)H0; (CH3)2Sn(cit)OH2,; [(CH3)2Sn]2(cit)OH0; [(CH3)2Sn]2(cit)(OH)2,} were found. All the species formed in this system are quite stable and formation percentages are fairly high. For example, at pH = 7.5 and C = Ccit = 10 mmol l,1, ,% for [(CH3)2Sn]2(cit)(OH)2, and (CH3)2Sn(cit)OH2, species reaches 65%. Overall thermodynamic parameters obtained show that the main contribution to stability is entropic in nature. Thermodynamic parameters were discussed in comparison with a simple tricarboxylate ligand (1,2,3-propanetricarboxylate). Two empirical relationships were derived from thermodynamic formation parameters. Spectroscopic results fully confirm the speciation model defined potentiometrically and show the mononuclear species to have an eq-(CH3)2Tbp structure with different arrangements around the metal, while for [(CH3)2Sn]2(cit)(OH)2, there are two different Sn(IV) environments, namely trans -(CH3)2 octahedral and cis -(CH3)2 Tbp. Copyright © 2005 John Wiley & Sons, Ltd. [source] Taking Stock of Corporate Governance Research While Looking to the FutureCORPORATE GOVERNANCE, Issue 3 2009Igor Filatotchev ABSTRACT Manuscript Type: Editorial Research Question/Issue: This essay identifies some key issues for the analysis of corporate governance based on the articles within this special review issue coupled with our own perspectives. Our aim in this issue is to distil some research streams in the field and identify opportunities for future research. Research Findings/Results: We summarize the eight papers included in this special issue and briefly highlight their main contributions to the literature which collectively deal with the role and impact of corporate boards, codes of corporate governance, and the globalization of corporate governance systems. In addition to the new insights offered by these reviews, we attempt to offer our own ideas on where future research needs to be targeted. Theoretical Implications: We highlight a number of research themes where future governance research may prove fruitful. This includes taking a more holistic approach to corporate governance issues and developing an inter-disciplinary perspective by building on agency theory while considering the rich new insights offered by complementary theories, such as behavioral theory, institutional theory and the resource-based views of the firm. In particular, future corporate governance research needs to be conducted in multiple countries, particularly in emerging economies, if we want to move closer to the journal's aim of producing a global theory of corporate governance. Practical Implications: Our analysis suggests that analytic and regulatory approaches to corporate governance issues should move from a "one-size-fits-all" template to taking into account organizational, institutional and national contexts. [source] Transferring HR practices within multinational corporationsHUMAN RESOURCE MANAGEMENT JOURNAL, Issue 4 2007Ingmar Björkman There is extensive evidence that planned transfers of management practices by the headquarters of multinational corporations (MNCs) to foreign subsidiaries are not always successful. In this article, we outline a model of factors influencing the transfer of HR practices to MNC units abroad. The article has two main contributions. First, we develop a more holistic understanding of the outcome of HR practice transfer as encompassing three dimensions: implementation, internalisation and integration. Second, we expand current explanations of transfers of practices to foreign units. We argue that transfer of HR practices is a social process where the governance mechanisms used by the MNC, characteristics of the subsidiary HR systems, the social relationship between the subsidiary and MNC headquarters, and the transfer approach taken by headquarters management will influence the outcome of the process. [source] Neural network volatility forecastsINTELLIGENT SYSTEMS IN ACCOUNTING, FINANCE & MANAGEMENT, Issue 3-4 2007José R. Aragonés We analyse whether the use of neural networks can improve ,traditional' volatility forecasts from time-series models, as well as implied volatilities obtained from options on futures on the Spanish stock market index, the IBEX-35. One of our main contributions is to explore the predictive ability of neural networks that incorporate both implied volatility information and historical time-series information. Our results show that the general regression neural network forecasts improve the information content of implied volatilities and enhance the predictive ability of the models. Our analysis is also consistent with the results from prior research studies showing that implied volatility is an unbiased forecast of future volatility and that time-series models have lower explanatory power than implied volatility. Copyright © 2008 John Wiley & Sons, Ltd. [source] Taking stock of naturalistic decision makingJOURNAL OF BEHAVIORAL DECISION MAKING, Issue 5 2001Raanan Lipshitz Abstract We review the progress of naturalistic decision making (NDM) in the decade since the first conference on the subject in 1989. After setting out a brief history of NDM we identify its essential characteristics and consider five of its main contributions: recognition-primed decisions, coping with uncertainty, team decision making, decision errors, and methodology. NDM helped identify important areas of inquiry previously neglected (e.g. the use of expertise in sizing up situations and generating options), it introduced new models, conceptualizations, and methods, and recruited applied investigators into the field. Above all, NDM contributed a new perspective on how decisions (broadly defined as committing oneself to a certain course of action) are made. NDM still faces significant challenges, including improvement of the quantity and rigor of its empirical research, and confirming the validity of its prescriptive models. Copyright © 2001 John Wiley & Sons, Ltd. [source] Clinical versus statistical prediction: The contribution of Paul E. MeehlJOURNAL OF CLINICAL PSYCHOLOGY, Issue 10 2005William M. GroveArticle first published online: 22 JUL 200 The background of Paul E. Meehl's work on clinical versus statistical prediction is reviewed, with detailed analyses of his arguments. Meehl's four main contributions were the following: (a) he put the question, of whether clinical or statistical combinations of psychological data yielded better predictions, at center stage in applied psychology; (b) he convincingly argued, against an array of objections, that clinical versus statistical prediction was a real (not concocted) problem needing thorough study; (c) he meticulously and even-handedly dissected the logic of clinical inference from theoretical and probabilistic standpoints; and (c) he reviewed the studies available in 1954 and thereafter, which tested the validity of clinical versus statistical predictions. His early conclusion that the literature strongly favors statistical prediction has stood up extremely well, and his conceptual analyses of the prediction problem (especially his defense of applying aggregate-based probability statements to individual cases) have not been significantly improved since 1954. © 2005 Wiley Periodicals, Inc. J Clin Psychol 61: 1233,1243, 2005. [source] Photochemistry of CH3Mn(CO)5: A multiconfigurational ab initio studyJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 15 2006Leticia González Abstract The electronic spectroscopy of CH3Mn(CO)5 has been investigated by means of ab initio multiconfigurational MS-CASPT2/CASSCF calculations. The absorption spectrum is characterized by a series of Metal-Centered (MC) excited states in the UV energy domain (below 290 nm) that could be responsible for the observed photoreactivity starting at 308 nm. The upper part of the spectrum is overcrowded between 264 and 206 nm and dominated by a high density of Metal-to-Ligand-Charge-Transfer (MLCT) states corresponding mainly to 3dMn , ,*CO excitations. A non-negligible contribution of Metal-to-,-Bond-Charge-Transfer (MSBCT) states corresponding to 3dMn , ,*Mn-CH3 excitations is also present in the theoretical spectrum of CH3Mn(CO)5. However, in contrast to other transition metal hydrides and methyl substituted (HMn(CO)5, HCo(CO)4, and CH3Co(CO)4) these MSBCT transitions do not participate to the lowest bands of the spectrum as main contributions. The photochemistry of CH3Mn(CO)5, namely the loss of a CO ligand vs. the metal-methyl bond homolysis, is investigated by means of MS-CASPT2 states correlation diagrams. This study illustrates the complexity of the photodissociation mechanism of this class of molecules, which involves a large number of nearly degenerate electronic states with several channels for fragmentation. © 2006 Wiley Periodicals, Inc. J Comput Chem, 2006 [source] In vitro degradation of forage chicory (Cichorium intybus L.) by endopoly- galacturonaseJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 15 2007Xuezhao Sun Abstract BACKGROUND: Leaves of forage chicory break down rapidly in the rumen despite little or no rumination. Because chicory cell walls contain high concentrations of pectin, degradation of leaf midrib and leaf lamina tissues by pectinolytic enzymes was investigated. RESULTS: Treatment with endopolygalacturonase (endo-PG) degraded fresh intact chicory leaves to particles of less than 1 mm in length and solubilised more than 70% of the dry matter within 16 h. Uronic acids were released more extensively than neutral monosaccharides. In similar treatments, 77% of white clover leaflets and 12% of perennial ryegrass leaf blades were solubilised or broken down to particles with a size of less than 1 mm. The degradation of pectic polysaccharides in chicory midribs was monitored by immunofluorescence labelling with monoclonal antibodies JIM5 and JIM7 which target partially methyl-esterified epitopes of the homogalacturonan (HG) domain of pectin. Examination by fluorescence microscopy revealed that cell separation in the cortical parenchyma of chicory midrib following endo-PG treatment was associated with loss of HG from the middle lamella, the corners of intercellular spaces and from the tricellular junctions. CONCLUSION: The results of the current study suggest that one of the main contributions to chicory breakdown in the rumen may be cell separation caused by degradation of HG by pectinolytic enzymes from rumen bacteria. Copyright © 2007 Society of Chemical Industry [source] | ||||||||||||||||||||||||||||