The Structure of the Toyota Supply Network: An Empirical Analysis

Increasing awareness of the intrinsically complex nature of supply networks has brought the field of supply chain management into the domain of network science. However, due to the difficulties of acquiring large-scale and consistent empirical data sets, a more complete picture of a real-world supply network has remained remarkably elusive. In this paper, we present novel data that characterize the Toyota supply network, and identify key structural features using measures from social network analysis and the more recent field of network science. We show that the network structure for the Toyota supply network departs widely from the simplified models on which much previous work is based. Our analysis reveals the heterogeneous composition of the network and identifies key firms. Further analysis reveals the existence of constituent sub-networks, and we show that their structures reflect various factors, such as product categorization, geographical closeness and business alignment. Mapping the topology, geography, and distribution of productive capabilities for this supply network provides a critical first step for developing a more empirically-grounded theory of distributed production

Temporal motifs in patent opposition and collaboration networks

Patents are intellectual properties that reflect innovative activities of companies and organizations. The literature is rich with the studies that analyze the citations among the patents and the collaboration relations among companies that own the patents. However, the adversarial relations between the patent owners are not as well investigated. One proxy to model such relations is the patent opposition, which is a legal activity in which a company challenges the validity of a patent. Characterizing the patent oppositions, collaborations, and the interplay between them can help better understand the companies' business strategies. Temporality matters in this context as the order and frequency of oppositions and collaborations characterize their interplay. In this study, we construct a two-layer temporal network to model the patent oppositions and collaborations among the companies. We utilize temporal motifs to analyze the oppositions and collaborations from structural and temporal perspectives. We first characterize the frequent motifs in patent oppositions and investigate how often the companies of different sizes attack other companies. We show that large companies tend to engage in opposition with multiple companies. Then we analyze the temporal interplay between collaborations and oppositions. We find that two adversarial companies are more likely to collaborate in the future than two collaborating companies oppose each other in the future

Comparison of alterations in cerebral hemoglobin oxygenation in late life depression ans Alzheimer's disease as assessed by near-infrared spectroscopy

BACKGROUND: Patients with Alzheimer's disease (AD) often present with apathy symptoms resembling the decreased motivation observed in depressed patients. Therefore, differentiating the initial phase of AD from late life depression may be difficult in some cases. Near-infrared spectroscopy (NIRS) is a functional neuroimaging modality that uses near-infrared light to measure changes in hemoglobin concentration on the cortical surface during activation tasks. The objective of this study was to investigate differences in brain activation associated with late life depression and with AD by means of NIRS. METHODS: NIRS was performed in 30 patients with depression, 28 patients with AD, and 33 healthy controls, all aged 60 years or older. During two tasks, a verbal fluency task and a visuospatial task, changes in oxygenated hemoglobin concentration in the frontal and parietal cortices were investigated. RESULTS: In the visuospatial task, cortical activation was lower in the depressed group than in the AD group, and significant differences were observed in the parietal cortex. CONCLUSIONS: NIRS can detect differences in brain activation between patients with late life depression and those with AD. NIRS is a promising tool for the differential diagnosis of late life depression and AD.ArticleBEHAVIORAL AND BRAIN FUNCTIONS. 10:8 (2014)journal articl

Towards capturing heterogeneity of supply network structures and their temporal transitions: an investigation of supply relationships in the Japanese automobile industry

Empirical longitudinal data on supply relationships between car manufacturers (OEMs) and auto-parts suppliers in the Japanese automobile industry are studied systematically. Such supply relationship formations, which will have emerged over time, are likely to reflect various contingent factors such as industrial conditions (which affect OEMs’ procurement strategies and resulting product demands). There are other important factors such as the level of standardization of the product, and the skills required for manufacturing the product. Furthermore, the effects of such factors may vary from product to product, and year to year. Heterogeneity between the supply networks of various products is elucidated via characterization with several measures, and also via a visualization of the transitions of the network properties. Our systematic analysis of the data provides profound insight into how product markets may have become stabilized or more competitive, and how the market selection process may affect the evolution of the supply network characteristics. The proposed approach and findings of the study can contribute to supply network modeling, and lead to the prediction of future changes in product markets, as well as suppliers’ production strategy planning