Exclusivity and exclusion on platform markets

We examine conditions under which an exclusive license granted by the upstream producer of a component that some consumers regard as essential to one of two potential suppliers of a downstream platform market can make the unlicensed supplier unprofitable, although both firms would be profitable if both were licensed. If downstream varieties are close substitutes, an exclusive license need not be exclusionary. If downstream varieties are highly differentiated, an exclusive license is exclusionary, but it is not in the interest of the upstream firm to grant an exclusive license. For intermediate levels of product differentiation, an exclusive license is exclusionary and maximizes the upstream firm’s payoff

Null Models of Economic Networks: The Case of the World Trade Web

In all empirical-network studies, the observed properties of economic networks are informative only if compared with a well-defined null model that can quantitatively predict the behavior of such properties in constrained graphs. However, predictions of the available null-model methods can be derived analytically only under assumptions (e.g., sparseness of the network) that are unrealistic for most economic networks like the World Trade Web (WTW). In this paper we study the evolution of the WTW using a recently-proposed family of null network models. The method allows to analytically obtain the expected value of any network statistic across the ensemble of networks that preserve on average some local properties, and are otherwise fully random. We compare expected and observed properties of the WTW in the period 1950-2000, when either the expected number of trade partners or total country trade is kept fixed and equal to observed quantities. We show that, in the binary WTW, node-degree sequences are sufficient to explain higher-order network properties such as disassortativity and clustering-degree correlation, especially in the last part of the sample. Conversely, in the weighted WTW, the observed sequence of total country imports and exports are not sufficient to predict higher-order patterns of the WTW. We discuss some important implications of these findings for international-trade models.Comment: 39 pages, 46 figures, 2 table

Heterogeneity and the dynamics of technology adoption

We estimate the demand for a videocalling technology in the presence of both network effects and heterogeneity. Using a unique dataset from a large multinational firm, we pose and estimate a fully dynamic model of technology adoption. We propose a novel identification strategy based on post-adoption technology usage to disentangle equilibrium beliefs concerning the evolution of the network from observed and unobserved heterogeneity in technology adoption costs and use benefits. We find that employees have significant heterogeneity in both adoption costs and network benefits, and have preferences for diverse networks. Using our estimates, we evaluate a number of counterfactual adoption policies, and find that a policy of strategically targeting the right subtype for initial adoption can lead to a faster-growing and larger network than a policy of uncoordinated or diffuse adoption

Peer influence in network markets: a theoretical and empirical analysis

Network externalities spur the growth of networks and the adoption of network goods in two ways. First, they make it more attractive to join a network the larger its installed base. Second, they create incentives for network members to actively recruit new members. Despite indications that the latter "peer effect" can be more important for network growth than the installed-base effect, it has so far been largely ignored in the literature. We address this gap using game-theoretical models. When all early adopters can band together to exert peer influence-an assumption that fits, e.g., the case of firms supporting a technical standard-we find that the peer effect induces additional growth of the network by a factor. When, in contrast, individuals exert peer influence in small groups of size n, the increase in network size is by an additive constant-which, for small networks, can amount to a large relative increase. The difference between small, local, personal networks and large, global, anonymous networks arises endogenously from our analysis. Fundamentally, the first type of networks is "tie-reinforcing," the other, "tie-creating". We use survey data from users of the Internet services, Skype and eBay, to illustrate the main logic of our theoretical results. As predicted by the model, we find that the peer effect matters strongly for the network of Skype users-which effectively consists of numerous small sub-networks-but not for that of eBay users. Since many network goods give rise to small, local networks

Обзор местных медикаментозных средств, применяемых в лечении гнойно-некротических осложнений синдрома диабетической стопы

The article provides  an overview of local medicines used in wounds’ treatment  for patients with purulo-necrotic complications of diabetic foot syndrome (DFS) and the requirements  for these preparations  at the present-day stage of wound healing process development and also the principles of monitoring  of  wounds of different etiology. The above material also allows you to get acquainted with the classification of local medicines groups, their brief characteristics with highlighting the peculiarity of each group, strengths and weaknesses, indications, contraindications and possible mistakes of their using. Here is given the detailed description of  main groups modern wound coverings based on alginates, hydrocolloids, hydrogels and histo-equivalent-bioplastic material of hyaluronic acid. There were made conclusions about the lack of information on the real clinical effectiveness of modern dressings and about  numerous and not systematic approaches for measuring the course of the wound healing process using various biological models. This explains the urgency to improving the modern diagnostic algorithm for measuring the course of the wound healing process and the need to develop an universal model that allows to identify its peculiarities and regularities, including efficiency assessment for local treatment of DFS purulo-necrotic complications.В статье представлены обзор местных медикаментозных средств, применяемых для лечения ран пациентов с гнойнонекротическими осложнениями синдрома диабетической стопы (СДС), требования, предъявляемые к этим препаратам на современном этапе развития учения о раневом процессе и принципах ведения ран различной этиологии. В приведенном материале можно также ознакомиться с классификацией групп местных медикаментозных средств, их краткой характеристикой с выделением особенностей каждой группы, сильных и слабых сторон, показаниями, противопоказаниями и возможными ошибками их использования. Дано подробное описание основных групп современных раневых покрытий на основе альгинатов, гидроколлоидов, гидрогелей и гистоэквивалент-биопластического материала гиалуроновой кислоты. Сделаны выводы о дефиците информации по поводу реальной клинической эффективности современных средств для местного медикаментозного лечения, о многочисленных и не всегда системных подходах к оценке течения раневого процесса с использованием различных биологических моделей. Этим объясняется актуальность совершенствования современного диагностического алгоритма при оценке течения раневого процесса и необходимость создания универсальной модели, позволяющей выявлять его особенности и закономерности, в том числе для оценки эффективности средств местного лечения гнойно-некротических осложнений СДС