Pitfalls in vertical arrangements

A popular way of obtaining essential inputs requires the establishment of an input production joint venture (IPJV) in the upstream (U) section of the vertical chain of production by firms competing and selling final goods in the downstream (D) section of the vertical chain. In spite of the apparently simple arrangement there are many possible governances for the management of the IPJV according to the ownership structure and to the degree of delegation granted to the IPJV by parent firms. We explore the best sustainable governance arrangement for the IPJV. We address this question in a duopoly framwork and we find a large area of impossible vertical arrangements associated with technological asymmtery. The most likely governance of the vertical arrangment associated to the IPJV is total independence.

Asymmetric Complements in a Vertically Differentiated Market: Competition or Integration?

We study the effects of integration of asymmetric complements when they are vertically differentiated. While confirming the standard effects of integration, namely the internalization of the double marginalization externality and the reduction of competition, we point out a new positive quality effect, due to an increase in the average quality of the goods on sale. We also characterize the conditions under which integration turns out to be optimal for both firms' and consumers. We thus provide valuable directions for competition agencies when considering the joint ownership in vertically differentiated markets

Asymmetric Complements in a Vertically Differentiated Market: Competition or Integration?

We study the effects of integration of asymmetric complements when they are vertically differentiated. While confirming the standard effects of integration, namely the internalization of the double marginalization externality and the reduction of competition, we point out a new positive quality effect, due to an increase in the average quality of the goods on sale. We also characterize the conditions under which integration turns out to be optimal for both firms' and consumers. We thus provide valuable directions for competition agencies when considering the joint ownership in vertically differentiated markets

Turmoil over the crisis: innovation capabilities and firm exit

This work investigates the relationship between the characteristics and survival probabilities of firms, distinguishing between “involuntary” firm exit and exit by merger and acquisition (M&A). More in detail, we study how, and to what extent, innovation capabilities, as proxied by patents and trademarks, are able to shape, together with standard performance variables, the observed dynamics at the firm level. By using comprehensive data on Italian firms from business registers, we separate the administrative procedures leading to “involuntary” exit from those ending up with an event of M&A. We find that while higher productivity is associated with a lower probability of “involuntary” exit, productivity increases the chances of being the target for M&A. As far as intellectual property instruments are concerned, they tend to reduce the probability of both “involuntary” exit and M&A. However, the relative importance of the two instruments differs according to the exit route: patents are more relevant than trademarks in preventing “involuntary” exit, while the opposite is true for M&A. Plain English Summary We investigate firm’s exit after a crisis. Overall innovation plays a positive role, but the relative importance of IP depends on the exit route: patents are more relevant than trademarks against “involuntary” exit, while the opposite is true for M&A. We resort to the virtual universe of Italian limited liability firms from manufacturing, trade, and service to investigate the determinants of firm survival over the period 2010–2014. We scrutinize detailed administrative data on significant events occurring to firms to distinguish between events leading to involuntary exit and to M&A. In addition to the evidence on innovation, our results show that higher productivity decreases the probability of “involuntary” exit, yet productivity increases the chances of being the target for M&A. Taken together, these findings warn against a simplistic perspective on exit: the role of innovation and firm characteristics heavily depends on the exit route

Hedonic and environmental quality: A hybrid model of product differentiation

In this paper, we analyze how strategic competition between a green firm and a browncompetitor develops when their products are differentiated along two dimensions: hedonicquality and environmental quality. The former dimension refers to the pure (intrinsic) per-formance of the good, whereas the latter dimension has a positional content: buying greengoods satisfies the consumer’s desire to be portrayed as a socially worthy citizen. We con-sider the case in which these quality dimensions are in conflict with each other so that thehigher the hedonic quality of a good, the lower the corresponding environmental quality.We characterize the equilibrium configurations and discuss the policy implications derivingfrom our analysis

Lamellar and fibre bundle mechanics of the annulus fibrosus in bovine intervertebral disc

ArticleThe intervertebral disc is a multicomposite structure, with an outer fibrous ring, the annulus fibrosus, retaining a gel-like core, the nucleus pulposus. The disc presents complex mechanical behaviour, and it is of high importance for spine biomechanics. Advances in multiscale modelling and disc repair raised a need for new quantitative data on the finest details of annulus fibrosus mechanics. In this work we explored inter-lamella and inter-bundle behaviour of the outer annulus using micromechanical testing and second harmonic generation microscopy. Twenty-one intervertebral discs were dissected from cow tails; the nucleus and inner annulus were excised to leave a ring of outer annulus, which was tested in circumferential loading while imaging the tissue’s collagen fibres network with sub-micron resolution. Custom software was developed to determine local tissue strains through image analysis. Inter-bundle linear and shear strains were 5.5 and 2.8 times higher than intra-bundle strains. Bundles tended to remain parallel while rotating under loading, with large slipping between them. Inter-lamella linear strain was almost 3 times the intra-lamella one, but no slipping was observed at the junction between lamellae. This study confirms that outer annulus straining is mainly due to bundles slipping and rotating. Further development of disc multiscale modelling and repair techniques should take into account this modular behaviour of the lamella, rather than considering it as a homogeneous fibre-reinforced matrix.Henry Smith Charit

Experimental validation of a patient-specific model of orthotic action in adolescent idiopathic scoliosis

This is the author accepted manuscript. The final version is available from Springer via the DOI in this record.PURPOSE: Personalized modeling of brace action has potential in improving brace efficacy in adolescent idiopathic scoliosis (AIS). Model validation and simulation uncertainty are rarely addressed, limiting the clinical implementation of personalized models. We hypothesized that a thorough validation of a personalized finite element model (FEM) of brace action would highlight potential means of improving the model. METHODS: Forty-two AIS patients were included retrospectively and prospectively. Personalized FEMs of pelvis, spine and ribcage were built from stereoradiographies. Brace action was simulated through soft cylindrical pads acting on the ribcage and through displacements applied to key vertebrae. Simulation root mean squared errors (RMSEs) were calculated by comparison with the actual brace action (quantified through clinical indices, vertebral positions and orientations) observed in in-brace stereoradiographies. RESULTS: Simulation RMSEs of Cobb angle and vertebral apical axial rotation was lower than measurement uncertainty in 79 % of the patients. Pooling all patients and clinical indices, 87 % of the indices had lower RMSEs than the measurement uncertainty. CONCLUSIONS: In-depth analysis suggests that personalization of spinal functional units mechanical properties could improve the simulation's accuracy, but the model gave good results, thus justifying further research on its clinical application

Intervertebral disc characterisation by elastography: a preliminary study.

BiomecAM chai

Non-invasive biomechanical characterization of intervertebral discs by shear wave ultrasound elastography: a feasibility study.

PublishedJournal ArticleThe final publication is available at Springer via http://dx.doi.org/10.1007/s00330-014-3382-8OBJECTIVES: Although magnetic resonance is widely spread to assess qualitatively disc morphology, a simple method to determine reliably intervertebral disc status is still lacking. Shear wave elastography is a novel technique that allows quantitative evaluation of soft-tissues' mechanical properties. The aim of this study was to assess preliminary the feasibility and reliability of mechanical characterization of cervical intervertebral discs by elastography and to provide first reference values for asymptomatic subjects. METHODS: Elastographic measurements were performed to determine shear wave speed (SWS) in C6-C7 or C7-T1 disc of 47 subjects; repeatability and inter-operator reproducibility were assessed. RESULTS: Global average shear wave speed (SWS) was 3.0 ± 0.4 m/s; measurement repeatability and inter-user reproducibility were 7 and 10%, respectively. SWS was correlated with both subject's age (p = 1.3 × 10(-5)) and body mass index (p = 0.008). CONCLUSIONS: Shear wave elastography in intervertebral discs proved reliable and allowed stratification of subjects according to age and BMI. Applications could be relevant, for instance, in early detection of disc degeneration or in follow-up after trauma; these results open the way to larger cohort studies to define the place of this technique in routine intervertebral disc assessment. KEY POINTS: A simple method to obtain objectively intervertebral disc status is still lacking. Shear wave elastography was applied in vivo to assess intervertebral discs. Elastography showed promising results in biomechanical disc evaluation. Elastography could be relevant in clinical routine for intervertebral disc assessment.ParisTech BiomecAM chair programParisTechYves Cotrel FoundationsSociété GénéraleProteorCove