Energy modelling for technology assessment: the MARKAL approach

The primary objective of energy policy in many countries is to change the structure of their energy systems so as to reduce the dependence on imported oil. A large amount of funds is spent on energy research and development. The technologies competing for such funds have widely varying characteristics. These relate to costs and benefits, technical performance, environmental effects, the requirements for land, water and materials and the impact on employment. It is necessary to analyse these effects in some detail before decisions on technology programmes can be made. A complete assessment of the possible value of a particular technology cannot be made on an individual basis. It is necessary to consider many technologies simultaneously, competing against each other for various shares of the energy market. However, analysing the behaviour of the entire energy system requires the handling of an extensive amount of data and can only be done effectively with the help of a computerised system. The model, MARKAL, described in this paper is a multi-period linear programming model which has been developed and applied by 15 OECD countries for the purpose of energy technology research and development planning. Examples of the use of the model for this purpose are given both for the group as a whole and for individual countries. The model is structured so that an exogenously specified set of end-use demands must be satisfied given available technologies and energy supplies. The model allows for substitution possibilities in both the energy supply and demand sectors. A feature of the model is the use of varying objective functions such as minimum discounted costs, oil imports, or environmental effluents. These can be used individually or in combination in trade-off situations. The broader question of the use of energy modelling for technology assessment, including its limitations, is also discussed with particular reference to the insights that can be gained from the MARKAL model. Information from the MARKAL model has been used by the International Energy Agency to assist it in formulating a strategy for energy research development and demonstration.     

Dyaden,Gruppen und Teams: Die Rahmungen von Coachings und Supervisionen

This article examines what impact three different framings of personal oriented consulting interactions – dyads, groups and teams – have on the consulting situation. Intuitively consultants are aware that it makes a difference if a client is consulted in a face-to-face-interaction “under four eyes”, in the framework of a group which just started to know each other or in a team which is working together on regular basis. However, what are exactly the mechanisms which are working in the three different settings? And what exactly are their impacts on the consulting situation? This article provides first interpretations.     

Hypotheses testing for generalized order statistics with simple order restrictions on model parameters under the alternative

In applications of generalized order statistics as, for instance, reliability analysis of engineering systems, prior knowledge about the order of the underlying model parameters is often available and may therefore be incorporated in inferential procedures. Taking this information into account, we establish the likelihood ratio test, Rao's score test, and Wald's test for test problems arising from the question of appropriate model selection for ordered data, where simple order restrictions are put on the parameters under the alternative hypothesis. For simple and composite null hypothesis, explicit representations of the corresponding test statistics are obtained along with some properties and their asymptotic distributions. A simulation study is carried out to compare the order restricted tests in terms of their power. In the set-up considered, the adapted tests significantly improve the power of the associated omnibus versions for small sample sizes, especially when testing a composite null hypothesis.     

A Randomized,Waiting-List-Controlled Study Shows That Brief,Mindfulness-Based Psychological Interventions Are Effective for Treatment of Women’s Low Sexual Desire

We evaluated two treatment conditions for low sexual desire in women: one where participants were administered a mindfulness-based treatment protocol and another with exercises focusing on scheduled sex and motivations for sex in addition to the aforementioned protocol. Seventy women (M_age 39.2, SD = 9.8) with complaints of low sexual desire were randomly allocated to one of these treatment conditions or a waiting-list condition. Participants attended four individual sessions and completed homework exercises. Questionnaire data were collected before and after treatment and at follow-ups three and six months later. Primary outcomes were the Female Sexual Function Index (FSFI) desire subdomain and the Sexual Interest and Desire Inventory–Female (SIDI-F). Secondary outcomes were the Female Sexual Distress Scale–Revised (FSDS-R), the Revised Dyadic Adjustment Scale (RDAS), the Perceived Relationship Quality Components Inventory (PRQC), and the Brief Symptom Inventory–18 (BSI-18). Women in both treatment conditions reported significantly higher sexual desire (FSFI desire d = 0.75 to 1.06) immediately following treatment, compared to the waiting list. Improvements were sustained at follow-up, accompanied by improvements in some secondary outcomes. We found no significant differences between the treatment conditions in terms of treatment effectiveness. Our study adds to the literature suggesting that mindfulness-based treatments are suitable options for treating low sexual desire in women.     

Management und Teilzeit? – Eine empirische Analyse zur Verbreitung von Teilzeitarbeit unter Managerinnen und Managern in Europa

Part-time work helps organizations to ensure flexibility and allows employees to combine work and family duties. However, despite their desire to work reduced hours, many individuals work full-time – particularly those in leadership positions. This article therefore examines which factors contribute to the use of part-time work among managers. By analysing a data set that combines individual-level data from the European Labor Force Survey (2009) with country-level information from various sources, we identify the circumstances under which managers reduce their working hours and the factors that explain the variations in part-time work among managers in Europe. Our multi-level analyses show that normative expectations and cultural facts rather than legal regulations can explain these cross-national differences.     

Multivariate testing and model-checking for generalized order statistics with applications

The exponential family structure of the joint distribution of generalized order statistics is utilized to establish multivariate tests on the model parameters. For simple and composite null hypotheses, the likelihood ratio test (LR test), Wald's test, and Rao's score test are derived and turn out to have simple representations. The asymptotic distribution of the corresponding test statistics under the null hypothesis is stated, and, in case of a simple null hypothesis, asymptotic optimality of the LR test is addressed. Applications of the tests are presented; in particular, we discuss their use in reliability, and to decide whether a Poisson process is homogeneous. Finally, a power study is performed to measure and compare the quality of the tests for both, simple and composite null hypotheses.     

Options Contracts with Overbooking in the Air Cargo Industry

In today's world economy, which is marked by intensified international trade, air cargo acts as a key facilitator. However, cargo airlines continue to struggle to be profitable because of very high asset costs and substantial demand uncertainty. To improve upon this situation, we propose an options contract. Our model captures the main features of cargo trade between an airline and a freight forwarder and allows us to derive an optimal reservation policy. We then go on to analyze the impact of overbooking on the profit of the cargo capacity provider. The model is subsequently applied to real‐life booking data provided by a major cargo carrier. This enables us to compare current contractual arrangements with the ones proven optimal in the model. A numerical study provides insights about the impact of overbooking on contract parameters and profitability. Managerial insights to be drawn conclude this study.     

Random restricted matching and lower bounds for?combinatorial optimization

We prove results on optimal random extensions of trees over points in [0,1] ^d . As an application, we give a general framework for translating results from combinatorial optimization about the behaviour of random points into results for point sets with sufficiently high regularity. We furthermore introduce a new irregularity problem concerning Voronoi cells, which has applications in logistics.     

Ownership concentration beyond good and evil: is there an effect on corporate performance?

In this paper, we analyze the relationship between ownership concentration and firm performance, while accounting for the endogeneity of the ownership structure, a potential curvilinearity of the performance effect, differences in corporate governance systems, and alternative performance measures. Using a sample of 1,079 firms from 8 countries we find evidence for a curvilinear effect of ownership concentration on firm performance, which becomes insignificant after controlling for endogeneity. Hence, our results support the findings by Demsetz and Villalonga (J Corp Fin 7(3):209?C233, 2001). More research is needed to disentangle the contradictory findings in prior works.     

Die Verbreitung moderner Managementkonzepte im Mittelstand

Within existing studies on the diffusion of modern management concepts, such as Lean Management, Business Process Reengineering or Shareholder Value Management, small and medium-sized enterprises are frequently examined as a homogeneous group of hesitant adopters. Differences among small and medium-sized companies with regard to concept adoption can thus hardly be explained by referring to existing research. In this paper, we argue that differences in adoption patterns of modern management concepts across small medium-sized companies can be explained on the basis of their resource endowment and embedment in different social environments. We thereby employ central arguments from organizational diffusion theory. Based on a multivariate analysis of online-survey data on the diffusion of 22 modern management concepts among 272 German SMEs, our results show that adoption decisions are mainly based on relationships to local organizational environments, whereas concept awareness can be best explained by media-exposure.