310 research outputs found
Heat transfer between surfaces in contact - The effect of low conductance interstitial materials. Part 3 - Comparison of the effective thermal insulation for interstitial materials under compressive loads
Effective thermal insulation characteristics of interstitial materials under compression loads and varying temperature
Cartel overcharges and the deterrent effect of EU competition law
This paper examines cartel overcharges for the European market. Using
a sample of 191 overcharge estimates and several parametric and semi-
parametric estimation procedures, the impact of different cartel charac-
teristics and the market environment on the magnitude of overcharges is
analyzed. The mean and median overcharge rates are found to be 20.70
percent and 18.37 percent of the selling price and the average cartel du-
ration is 8.35 years. Certain cartel characteristics and the geographic
region of cartel operation influence the level of overcharges considerably.
Furthermore, empirical evidence suggests that the currently existing fine
level of the EU Guidelines is too low to achieve optimal deterrence
Mapping the areas of research on intellectual capital throughout a period of dynamic environmental changes
Theoretical background: Intellectual capital is perceived as a global economy driving factor. Many researchers highlight that it is an ingredient improving the functional gear of almost any organisation. Some voices have simultaneously appeared in scientific discussions claiming that the concept of intellectual capital management may not be fully applicable, either in conditions of economic downturn or during turbulent changes. A whole spectrum of external factors then come to the floor, affecting the situation of a company, while the periods of economic perturbations discourage investments in human resources and hamper HR initiatives. Therefore, in these changing economic conditions, a question arises about the rationale for and the directions of the development on the research on intellectual capital, and the concept itself undergoes a practical verification of suitability and usefulness. This is a particularly interesting field of research because the transformations, which take place in the environment of enterprises, create specific expectations, which should be met within the framework of ongoing research projects on the intellectual capital.Purpose of the article: The aim of this article is to identify the dominant topical trends and networks of research directions in the subject of intellectual capital and their changes over time. The study attempts to illustrate these changes.Research methods: Having employed the text mining method, nearly 5,000 scientific articles on intellectual capital were analysed. Consequently, this extensive literature review enabled mapping of the network of links among the research directions in this area.Main findings: The results of the study have provided a fairly deep insight into the trends in the research on intellectual capital over the years. The results also reflect the vastness of the subject and the scope of the issues addressed over the past and present years. The interest in the concept of intellectual capital management continues and the dynamics of changes in the environment of the modern enterprise is not at all insignificant. The clusters, identified in the research on intellectual capital, have been opening new theoretical, pragmatic and methodological horizons. The analysis, carried out within the study network, confirmed the multifaceted nature of the network of research directions in the area of intellectual capital. In addition, the new research trends, which have been emerging in this area, clearly respond both to the dynamic changes in the business environment and to the doubts about the scale of activities, undertaken with regard to the intellectual capital management. Thus, in this situation, the periods of crisis and instability appear on one hand as a serious threat to the issue of intellectual capital management, while on the other, they can be perceived as an opportunity to renew the existing management concepts.Theoretical background: Intellectual capital is perceived as a global economy driving factor. Many researchers highlight that it is an ingredient improving the functional gear of almost any organisation. Some voices have simultaneously appeared in scientific discussions claiming that the concept of intellectual capital management may not be fully applicable, either in conditions of economic downturn or during turbulent changes. A whole spectrum of external factors then come to the floor, affecting the situation of a company, while the periods of economic perturbations discourage investments in human resources and hamper HR initiatives. Therefore, in these changing economic conditions, a question arises about the rationale for and the directions of the development on the research on intellectual capital, and the concept itself undergoes a practical verification of suitability and usefulness. This is a particularly interesting field of research because the transformations, which take place in the environment of enterprises, create specific expectations, which should be met within the framework of ongoing research projects on the intellectual capital.Purpose of the article: The aim of this article is to identify the dominant topical trends and networks of research directions in the subject of intellectual capital and their changes over time. The study attempts to illustrate these changes.Research methods: Having employed the text mining method, nearly 5000 scientific articles on intellectual capital were analysed. Consequently, this extensive literature review enabled mapping of the network of links among the research directions in this area.Main findings: The results of the study have provided a fairly deep insight into the trends in the research on intellectual capital over the years. The results also reflect the vastness of the subject and the scope of the issues addressed over the past and present years. The interest in the concept of intellectual capital management continues and the dynamics of changes in the environment of the modern enterprise is not at all insignificant. The clusters, identified in the research on intellectual capital, have been opening new theoretical, pragmatic and methodological horizons. The analysis, carried out within the study network, confirmed the multifaceted nature of the network of research directions in the area of intellectual capital. In addition, the new research trends, which have been emerging in this area, clearly respond both to the dynamic changes in the business environment and to the doubts about the scale of activities, undertaken with regards to the intellectual capital management. Thus, in this situation, the periods of crisis and instability appear on one hand as a serious threat to the issue of intellectual capital management, while on the other, they can be perceived as an opportunity to renew the existing management concepts
Applicability of Quantitative Functional MRI Techniques for Studies of Brain Function at Ultra-High Magnetic Field
This thesis describes the development, implementation and application of various quantitative functional magnetic resonance imaging (fMRI) approaches at ultra-high magnetic field including the assessment with regards to applicability and reproducibility.
Functional MRI (fMRI) commonly uses the blood oxygenation level dependent (BOLD) contrast to detect functionally induced changes in the oxy-deoxyhaemoglobin composition of blood which reflect cerebral neural activity. As these blood oxygenation changes do not only occur at the activation site but also downstream in the draining veins, the spatial specificity of the BOLD signal is limited. Therefore, the focus has moved towards more quantitative fMRI approaches such as arterial spin labelling (ASL), vascular space occupancy (VASO) or calibrated fMRI which measure quantifiable physiologically and physically relevant parameters such as cerebral blood flow (CBF), cerebral blood volume (CBV) or cerebral metabolic rate of oxygen (CMRO2), respectively.
In this thesis a novel MRI technique was introduced which allowed the simultaneous acquisition of multiple physiological parameters in order to beneficially utilise their spatial and temporal characteristics. The advantages of ultra-high magnetic field were utilised to achieve higher signal-to-noise and contrast-to-noise ratios compared to lower field strengths. This technique was successfully used to study the spatial and temporal characteristics of CBV, CBF and BOLD in the visual cortex. This technique is the first one that allows simultaneous acquisition of CBV, CBF and BOLD weighted fMRI signals in the human brain at 7 Tesla.
Additionally, this thesis presented a calibrated fMRI technique which allowed the quantitative estimation of changes in cerebral oxygen metabolism at ultra-high field. CMRO2 reflects the amount of thermodynamic work due to neural activity and is therefore a significant physical measure in neuroscience. The calibrated fMRI approach presented in this thesis was optimised for the use at ultra-high field by adjusting the MRI parameters as well as implementing a specifically designed radio-frequency (RF) pulse. A biophysical model was used to calibrate the fMRI data based on the simultaneous acquisition of BOLD and CBF weighted MRI signals during a gas-breathing challenge.
The reproducibility was assessed across multiple brain regions and compared to that of various physiologically relevant parameters. The results indicate that the degree of intra-subject variation for calibrated fMRI is lower than for the classic BOLD contrast or ASL. Consequently, calibrated fMRI is a viable alternative to classic fMRI contrasts with regards to spatial specificity as well as functional reproducibility. This calibrated fMRI approach was also compared to a novel direct calibration technique which relies on complete venous oxygenation saturation during the calibration scan via a gas-breathing challenge.
This thesis introduced several reliable quantitative fMRI approaches at 7 Tesla and the results presented are a step forward to the wider application of quantitative fMRI.:1 Introduction 3
2 Background to Functional Magnetic Resonance Imaging 7
2.1 Magnetic Resonance 7
2.1.1 Quantum Mechanics 7
2.1.2 The Classical Point of View 10
2.1.3 Radio Frequency Pulses 12
2.1.4 Relaxation Effects 13
2.1.5 The Bloch Equations 15
2.2 Magnetic Resonance Imaging 16
2.2.1 Data Acquisition 16
2.2.2 Image Formation 17
2.2.2.1 Slice Selection 17
2.2.2.2 Frequency Encoding 18
2.2.2.3 Phase Encoding 19
2.2.2.4 Mathematics of Image Formation 20
2.2.2.5 Signal Formation 22
2.3 Advanced Imaging Methods 24
2.3.1 Echo-Planar Imaging (EPI) 24
2.3.2 Partial Fourier Acquisition 25
2.3.3 Generalised Autocalibrating Partially Parallel Acquisition (GRAPPA) 25
2.3.4 Inversion Recovery (IR) 26
2.3.5 Adiabatic Inversion 26
2.3.5.1 Hyperbolic Secant (HS) RF pulses 28
2.3.5.2 Time Resampled Frequency Offset Corrected Inversion (tr-FOCI) RF Pulses 28
2.4 Physiological Background 29
2.4.1 Neuronal Activity 30
2.4.2 Energy Metabolism 31
2.4.3 Physiological Changes During Brain Activation 32
2.4.4 The BOLD Contrast 34
2.4.5 Disadvantages of the BOLD Contrast 35
2.5 Arterial Spin Labelling (ASL) 35
2.5.1 Pulsed Arterial Spin Labelling 37
2.5.2 Arterial Spin Labelling at Ultra-High Field 41
2.6 Vascular Space Occupancy (VASO) 42
2.6.1 VASO at Ultra-High Field 44
2.6.2 Slice-Saturation Slab-Inversion (SS-SI) VASO 45
2.7 Calibrated Functional Magnetic Resonance Imaging 47
2.7.1 The Davis Model 47
2.7.2 The Chiarelli Model 50
2.7.3 The Generalised Calibration Model (GCM) 52
3 Materials and Methods 53
3.1 Scanner Setup 53
3.2 Gas Delivery and Physiological Monitoring System 53
3.3 MRI Sequence Developments 55
3.3.1 Tr-FOCI Adiabatic Inversion 55
3.3.2 Optimisation of the PASL FAIR QUIPSSII Sequence Parameters 60
3.3.3 Multi-TE Multi-TI EPI 64
4 Experiment I: Comparison of Direct and Modelled fMRI Calibration 68
4.1 Background Information 68
4.2 Methods 69
4.2.1 Experimental Design 69
4.2.2 Visuo-Motor Task 70
4.2.3 Gas Manipulations 71
4.2.4 Scanning Parameters 71
4.2.5 Data Analysis 72
4.2.6 M-value Modelling 72
4.2.7 Direct M-Value Estimation 73
4.3 Results 74
4.4 Discussion 79
4.4.1 M-value Estimation 79
4.4.2 BOLD Time Courses 82
4.4.3 M-Maps and Single Subject Analysis 82
4.4.4 Effects on CMRO2 Estimation 83
4.4.5 Technical Limitations and Implications for Calibrated fMRI 84
4.5 Conclusion 89
5 Experiment II: Reproducibility of BOLD, ASL and Calibrated fMRI 90
5.1 Background Information 90
5.2 Methods 91
5.2.1 Experimental Design 91
5.2.2 Data Analysis 91
5.2.3 Reproducibility 93
5.2.4 Learning and Habituation Effects 95
5.3 Results 95
5.4 Discussion 101
5.4.1 Breathing Manipulations 102
5.4.2 Functional Reproducibility 107
5.4.3 Habituation Effects on Reproducibility 109
5.4.4 Technical Considerations for Calibrated fMRI 110
5.5 Conclusion 112
6 Experiment III: Simultaneous Acquisition of BOLD, ASL and VASO Signals 113
6.1 Background Information 113
6.2 Methods 114
6.2.1 SS-SI VASO Signal Acquisition 114
6.2.2 ASL and BOLD Signal Acquisition 114
6.2.3 Experimental Design 114
6.2.4 Data Analysis 115
6.3 Results 115
6.4 Discussion 116
6.5 Conclusion 120
7 Conclusion and Outlook 12
The appeals process : an empirical assessment
The appeals process – whereby the losing party of an administrative or judicial decision can
seek reconsideration of their arguments before a higher institution – is an important
mechanism to correct legal errors and to improve existing laws and regulations. We use data
of 467 firm groups that participated in 88 cartels convicted by the European Commission
between 2000 and 2012 to study both the characteristics of firm groups filing an appeal and
the factors that determine their successfulness in terms of fine reduction. Applying discrete
choice models and a two-stage hurdle model, we find that while some characteristics – such
as the size and financial condition of the firm group or the clarity of fine guidelines – only
affect the probability to file an appeal, other factors such as the size of the fine imposed in
connection to characteristics as ringleader, repeat offender or leniency applicant influence
both the probability and the success of an appeal. We take our empirical results to derive
conclusions for both firms and public policy makers
Encapsulation of ascorbic acid promotes the reduction of Maillard reaction products in UHT milk
The presence of amino groups and carbonyls renders fortified milk with ascorbic acid particularly susceptible to the reduction of available lysine and to the formation of Maillard reaction products (MRPs), as Nε-(Carboxyethyl)-L-lysine (CEL), Nε-(Carboxymethyl)-L-lysine (CML), Amadori products (APs) and off-flavors. A novel approach was proposed to control the Maillard reaction (MR) in fortified milk: ascorbic acid was encapsulated in a lipid coating and the effects were tested after a lab scale UHT treatment. Encapsulation promoted a delayed release of ascorbic acid and a reduction in the formation of MRPs. Total lysine increased up to 45% in milk with encapsulated ascorbic acid, while reductions in CML, CEL and furosine ranged from 10% to 53% compared with control samples. The effects were also investigated towards the formation of amide-AGEs (advanced glycation end products) by high resolution mass spectrometry (HRMS) revealing that several mechanisms coincide with the MR in the presence of ascorbic acid (AA)
Do cartel breakdowns induce mergers? : Evidence from EC cartel cases
We investigate the impact of cartel breakdowns on merger activity. Merging information on
cartel cases decided by the European Commission (EC) between 2000 and 2011 with a
detailed data set of worldwide merger activity, we find that, first, the average number of all
merger transactions increase by up to 51 percent when comparing the three years before the
cartel breakdowns with the three years afterwards. Second, for the subset of horizontal
mergers, merger activity is found to increase even more – by up to 83 percent – after the cartel
breakdowns. Our results not only suggest that competition authorities should consider
mergers as potential ‘second-best’ alternative to cartels but also imply that resource
(re)allocations in competition authorities, law practices and economic consultancies may
become necessary to handle the increase in merger cases
Estimating consumer damages in cartel cases
We use consumer panel data to calculate the damage suffered by German consumers due to a
detergent cartel that was active between 2002 and 2005 in eight European countries. Applying
before-and-after and difference-in-differences estimations we find average overcharges between
6.7 and 6.9 percent and an overall consumer damage of about 13.2 million Euro over the
period from July 2004 until March 2005. Under the assumptions that the cartel-induced share
on turnover is representative for the entire cartel period and all affected markets, the overall
consumer damage would even sum up to about 315 million Euro. Our results further suggest
that the retailers reacted to the price increases of the cartel firms via price increases for their
own detergent products, resulting in significant umbrella effects. We quantify the damage due
to this umbrella pricing to a total of about 7.34 million Euro. With respect to the discussion
whether special procedures for bringing collective actions should be available in the EU, our
results are important to the extent that we show how consumer associations can use consumer
panel data in order to claim damages before national courts and thereby actively fulfill their
mandate of consumer protection
A primer on damages of cartel suppliers - determinants, standing US vs. EU and econometric estimation
While private actions for damages by customers against price-cartels receive much attention, the treatment of other groups affected by such conspiracies is largely unresolved. This article narrows the research gap with respect to suppliers to a downstream price cartel. First, we show that such suppliers incur losses driven by a direct quantity, a price and a cost effect. We then analyze whether suppliers are entitled to claim these losses as damages in the two leading competition law regimes. We find that, while the majority view in the US denies standing, the emerging position in the EU and important member states is to grant supplier standing. We argue that this can indeed be justified in view of the different institutional context and the goals assigned to the right to damages in the EU. We finally present an econometric approach based on residual demand estimation that allows to quantify all determinants of cartel suppliers’ damages, thereby showing that supplier damage claims are a viable option in practice that can contribute to full compensation and greater cartel deterrence
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