NETWORK INTERACTIONS AND MUTUAL DEPENDENCE: A TEST IN THE CAR INDUSTRY

By engaging in specific investments a firm may develop a unique competence value for its partner, which makes the partners mutually dependent. This may neutralize any hold-up risk of an opportunistic partner that is tempted to exploit the dependence and appropriate a greater share of the value added in the relation. The purpose of this paper is to investigate such mechanisms of mutual dependence. The analysis builds on previous theoretical and empirical research by the authors. It is based on an integration of transaction cost economics with the resource (competence, capabilities) view and a social exchange view, from a dynamic perspective. The paper asks the following: How do competencies develop in interaction between firms? The social exchange view brings in trust as an important dimension of governance. The research question asks how risks of mutual dependence between firms may be mitigated without either hierarchical or legal control. Five hypotheses concerning such mechanisms of mutual dependence are tested on data from the car industry.     

Basic study of MR-dacryocystography

We developed MR-dacryocystography as a non-invasive, safer imaging technique for canaliculi, the nasolacrimal duct and lacrimal sac by dropping saline solution and diluted Gd-DTPA solution into the eye. The diluted Gd-DTPA solution was found to create no local irritation in the eyes of rabbits and normal volunteers. Lacrimal sacs and ducts were well visualized in all of 10 normal volunteers by using the saline solution or the diluted Gd-DTPA solution. Canaliculi were visualized in 4-7 cases on thin-slice axial images. MR-dacryocystography was suggested to be a useful screening examination for lacrimal outflow disorders.     

Neighbourhood effects and social mobility: a longitudinal analysis

What impact do neighbourhoods have on social mobility? For years, this question has received widespread international attention in scholarly debates and within society at large. This paper seeks to contribute to this discussion by presenting the results of an investigation into the relationship between household social mobility and the composition of the residential environment. The analyses are based on an extensive empirical longitudinal study conducted in the Netherlands. The most remarkable conclusion is that, in the Dutch context, the environment has only a modest influence on the social mobility of households with a weak economic position. It was found that the chance of a household living purely on welfare benefits at the beginning of the study period to escape the ‘welfare trap’ was barely dependent on the number of similarly challenged households in the immediate vicinity. Interestingly, the environment proved to have a more powerful effect on the social mobility of households with a stronger economic position. The probability that households with at least one paid job at the beginning of the research would still have a job at the end clearly decreases as the share of benefit-dependent households in the neighbourhood rises. A possible explanation for this is that for the first category (weak starting position) the negative effect of their own welfare situation is far more determinative for their future prospects than the compo sition of their environment. Because these negative individualistic conditions are absent for the second category (stronger starting position), environmental factors may play a relatively larger role. Another interpretation is that area-based policies are not just targeting the areas with bigger problems more intensively, but especially the long-term unemployed in these areas, and not so much the short-term unemployed (those who had a job at the start of the research period and lost the job afterwards).     

Surgical treatment of traumatic rupture of the aortic valve with dove-coo murmur--case report

Aortic regurgitation due to traumatic rupture of the aortic valve with dove-coo murmur is rare. A 71-year-old man was admitted for cardiac failure due to aortic regurgitation with dove-coo murmur, 4 years after the traffic accident. The aortic valve replacement was performed and his postoperative course was good. The aortic valve was tricuspid valve with the tear in the left side of right coronary cusp, and the size of the tear was 7 mm. The aortic valve was not recognized the findings of inflammatory or rheumatic change in the pathological study.     

The effect of hippocampal dentate granule cell lesions upon the limbic seizure model of rats

The purpose of this study was to determine the role of dentate granule cells upon limbic seizure of Wistar rat caused by unilateral intra-amygdaloid administration of kainic acid (KA). Stereotactic surgery was performed in Wistar rats and stainless steel injection chemitorode was inserted in the left amygdala. Left dentate granule cells lesion were induced by microinjection of colchicine. The rats obtained recovery period for 7 days, postoperatively. The rats were divided into two groups. One group were used for observation of symptoms and electroencephalographic findings during the limbic seizure for 6 hours after the KA injection. Another group was processed for measuring local cerebral glucose utilization (LCGU) during limbic seizure status. The histological study demonstrated a selective loss of dentate granule cells in the left hippocampus 7 days after the colchicine injection. After the KA injection, initiation of the spike discharge was significantly retarded not only in the hippocampus (from 6.01 min. to 37.25 min.) but also in the amygdala (from 2.96 min. to 10.8 min.). Progression, frequency and intensity of the KA induced seizures were also inhibited by the colchicine-induced dentate granule cells lesion. During limbic seizure status, LCGU obtained by 14C-deoxyglucose autoradiography were significantly decreased not only in the hippocampus but also in the amygdala on the site of KA injection. These data suggest that hippocampal dentate granule cells play an important role on initiation and progression of the KA induced limbic seizure. The result suggested that there was an acceleration mechanism of the limbic seizure between amygdala and hippocampus.     

Rapid Sintering of Silica Xerogel Ceramic Derived from Sago Waste Ash Using Sub-millimeter Wave Heating with a 300 GHz CW Gyrotron

In this paper, we present and discuss experimental results from a microwave sintering of a silica-glass ceramic, produced from a silica xerogel extracted from a sago waste ash. As a radiation source for the microwave heating a sub-millimeter wave gyrotron (Gyrotron FU CW I) with an output frequency of 300 GHz has been used. The powders of silica xerogel have been dry pressed and then sintered at temperatures ranging from 300°C to 1500°C. The influence of the sintering temperature on the technological properties such as porosity and bulk density was studied in detail. Furthermore, X-ray diffraction (XRD) and Fourier Transform Infrared (FTIR) spectroscopy have been used in order to study the structure of the produced silica glass-ceramics. It has been found that the silica xerogel crystallizes at a temperature of 800°C, which is about 200°C lower than the one observed in the conventional process. The silica xerogel samples sintered by their irradiation with a sub-millimeter wave at 900°C for 18 minutes are fully crystallized into a silica glass-ceramic with a density of about 2.2 g/cm³ and cristobalite as a major crystalline phase. The results obtained in this study allow one to conclude that the microwave sintering with sub-millimeter waves is an appropriate technological process for production of silica glass-ceramics from a silica xerogel and is characterized with such advantages as shorter times of the thermal cycle, lower sintering temperatures and higher quality of the final product.     

Microstructural evolution of magnesia-based castables containing microsilica

The higher performance of refractory materials applied in steelmaking vessels is mainly associated with the development of high-magnesia bricks. However, the same success has not yet been attained for the production of high-quality magnesia-based castables, due to the well-known magnesia hydration trend. In order to overcome this drawback, microsilica addition was tested as an anti-hydration additive in the present work. As it also leads to liquid formation at high temperatures in high-alumina CAC-containing castable compositions, the microstructural development of microsilica-containing magnesia-based castables was also analyzed by scanning electron microscopy, thermodynamics simulations and sintering assisted tests. According to the results, microsilica hindered the magnesia hydration and provided an additional bonding mechanism due to the reaction with MgO and water. Moreover, it helped to control the material's volumetric change by reducing the expansion associated with the spinel formation and also the shrinkage level afterwards.     

Bridging the social divide? reflections on current Dutch neighbourhood policy

Current Dutch urban policy has opted for a focused approach to solve urban social problems. The Minister of ‘Housing, Neighbourhoods and Integration’ aims at tackling social deprivation and liveability problems in a limited number of neighbourhoods. Several assumptions underpin the policy ambitions: e.g., a strong interrelationship between social deprivation and liveability; a clear social and spatial divide in Dutch society; and extra negative effects of problem accumulation. In this paper, these assumptions are tested. It is concluded that the two types of problems are in fact unrelated; targeting a limited number of neighbourhoods does not effectively address social deprivation. Furthermore, there is yet insufficient research to support the idea that there would be extra negative effects associated with an accumulation of social deprivation and liveability problems.

The corrosion and microstructure relationship for cement-bonded spinel refractory castables

Due to the lack of studies addressing the relationship between chemical and microstructural features and the corrosion resistance of castables containing pre-formed and in situ spinel (MgAl₂O₄), the main aspects related to the different wear rates of these compositions when in contact with steel ladle slags have not been properly stated. Considering this scenario, this work presents the slag resistance analysis of castables designed by different spinel incorporation routes (in situ formation, pre-formed spinel addition and both). A high-iron oxide containing industrial slag was used and the results indicated that the role of the distinct CA₆ (CaO·6Al₂O₃) distribution in the castable's microstructure before the slag attack was more relevant than the spinel ability as an ion trapper. The location of CA₆ crystals in the in situ spinel-forming castable led to a suitable physico-chemical protection of both, the tabular alumina aggregates and the matrix, during the experiment. For the pre-formed spinel-containing castable, the former CA₆ presence only in the matrix resulted in a high dissolution of alumina from the aggregates into the liquid during the corrosion test and a great amount of CA₆ crystals was formed. Cracks were then generated and followed by further cycles of penetration and chemical reactions, which spoiled the refractory's performance.     

Contribution of “Soils and Foundations” to Studies on Rainfall-Induced Slope Failure

The many recent slope failures due to heavy rainfall have been accompanied by significant loss of life, and massive damage to infrastructures and heritage. Many studies have been done to investigate the mechanism of rainfall-induced slope failures and establish a prevention system for slope disasters. In this paper, the state-of-the-art research works on slope failures due to rainfall published in the journal of Soils and Foundations (S&F) during the latest 50 years are reviewed and summarized. This report is written with the perspective that knowledge of unsaturated soil mechanics is necessary to elucidate the mechanism of rainfall-induced slope failure.