Evidence for contact delocalization in atomic scale friction

We analyze an advanced two-spring model with an ultra-low effective tip mass to predict nontrivial and physically rich 'fine structure' in the atomic stick-slip motion in Friction Force Microscopy (FFM) experiments. We demonstrate that this fine structure is present in recent, puzzling experiments. This shows that the tip apex can be completely or partially delocalized, thus shedding new light on what is measured in FFM and, possibly, what can happen with the asperities that establish the contact between macroscopic sliding bodies.Comment: 4 pages text and 3 figure

Proximity, knowledge base and the innovation process : the case of Unilever's Becel diet margarine

The proximity concept refers to types of inter-organizational relationships that are expected to facilitate interactive learning and collaborative innovation. Different forms of proximity include geographical, cognitive, social, institutional and organizational proximity. Following an extensive case study of a new diet margarine developed by Unilever, we extend the proximity framework by theorizing how the relative importance of each proximity dimension depends on the type of knowledge being produced, where we distinguish between analytical, synthetic and symbolic knowledge. We argue that our theoretical framework in principle applies to product innovations in all science-based industries

Microscale friction reduction by normal force modulation in MEMS.

Friction in MEMS-scale devices is troublesome because it can result in lateral stiction of two sliding surfaces. We have investigated the effect of modulation of the normal force on the friction between two sliding MEMS surfaces, using a fully MEMS-based tribometer. We have found that the friction is reduced significantly when the modulation is large enough. A simple model is presented that describes the friction reduction as a function of modulation frequency as well. Using this technique, lateral stiction-related seizure of microscopic sliding components can be mitigated

Spatial differentiation in industrial dynamics : a core-periphery analysis based on the Pavitt-Miozzo-Soete taxonomy

We compare the industrial dynamics in the core, semi-periphery and periphery in The Netherlands in terms of firm entry-exit, size, growth and sectoral location patterns. The contribution of our work is to provide the first comprehensive study on spatial differentiation in industrial dynamics for all firm sizes and all sectors, including services. We find that at the aggregate level the spatial pattern of industrial dynamics is consistent with the spatial product lifecycle thesis: entry and exit rates are highest in the core and lowest in the periphery, while the share of persistently growing firms is higher in the periphery than in the core. Disaggregating the analysis to the sectoral level following the Pavitt-Miozzo-Soete taxonomy, findings are less robust. Finally, sectoral location patterns are largely consistent with the spatial product lifecycle model: Fordist sectors are over-represented in the periphery, while sectors associated with the ICT paradigm are over-represented in the core, with the notable exception of science-based manufacturing

Diffusion of ideas, social reinforcement and percolation

This paper analyzes how social structure and social reinforcement affect the diffusion of an idea in a population of human agents. A percolation approach is used to model the diffusion process. This framework assumes that information is local and embedded in a social network. We introduce social reinforcement in the model by softening the condition to adopt when the number of adopting neighbors increases. Our numerical analysis shows that social reinforcement severely affects the output of the process. Some ideas with an original value so low that it would never get diffused can be spread due to the strength of social reinforcement. This effect also interacts with the structure of the network, with a more sizeable impact on small worlds with a low rewiring probability. Also, social reinforcement completely changes the effect of clustering links, because sequential adoption of neighbors can make one agent adopt at later stages

Diffusion of ideas and complex propagations

Trabajo presentado a la DRUID Academy Conference, celebrada en Aalborg (Dinamarca) del 21 al 23 de enero de 2015.This paper analyzes how social structure and social reinforcement affect the diffusion of an idea in a population of human agents. A percolation approach is used to model the diffusion process. This framework assumes that information is local and embedded in a social network. We introduce social reinforcement in the model by softening the condition to adopt when the number of adopting neighbors increases. Our numerical analysis shows that social reinforcement severely affects the output of the process. Some ideas with an original value so low that it would not get diffused through percolation can be spread due to the strength of social reinforcement. This effect also interacts with the structure of the network, getting a more sizeable impact on small worlds with a low rewiring probability. Also, social reinforcement completely changes the effect of clustering links, because sequential adoption of neighbors can make one agent adopt at later stages.Peer Reviewe

The sensing paradox in service innovation: Too much user-producer interaction?

Trabajo presentado a la DRUID15 Conference on: "The Relevance of Innovation" celebrada en Roma (Italia) del 15 al 17 de junio de 2015.This study seeks to explain the paradox that firms most engaged in fulfilling actual user needs might be the ones who benefit less from a capability for systematically evaluating market demands. Service-oriented innovation research stresses that the relational nature of service delivery, especially when customized, provides opportunities for firms to engage in intensive user-producer interaction already during their regular business activities. We examine under which conditions having a strong sensing user needs capability can be a weakness rather than a strength for such firms. By using NK-logic, we modelled the conjunction of customer and firm behaviour with respect to sending and sensing user feedback. Our simulations resulted in a hypothesis regarding the relation between various interactive search strategies on the one hand, and innovativeness on the other hand. Subsequently, we used survey data from 292 respondents to verify these findings empirically. Our regression results suggest that, for firms who provide client-specific services, there is limited value in investing in an ability to monitor and evaluate user feedback closely. Having a sensing capability and receiving user requests has a negative interaction effect for firms providing customized solutions, while this effect is positive when firms do not tailor their services. The results confirm that focusing too much on articulated market demands might prevent customizing firms from introducing commercially successful service solutions. With these findings, we support innovation managers dealing with the strategic dilemma whether or not to devote resources to sensing capabilities.Peer reviewe

Diffusion in small worlds with homophily and social reinforcement:A theoretical model

We introduce homophily in a percolation model of word-of-mouth diffusion in social networks by reorganizing the nodes according to similarity in preferences for adoption of an innovation. Such preferences are described by a “minimum utility requirement” for an agent to adopt. We show that homophily removes the non-linear relation between preferences and diffusion in the standard percolation model with a high diffusion regime (“hit”) and a low diffusion regime (“flop”). Instead, in a model with perfect homophily, the final diffusion scales linearly with individual preferences: all agents who are willing to adopt, do adopt the innovation. We also investigate the combined effect of homophily and social reinforcement in diffusion. Results indicate that social reinforcement renders clustered networks more efficient in terms of diffusion size for network with strong homophily, while the opposite is true for networks without homophily. The simple structure of our model allows to disentangle the effect of social influence, homophily and the network structure on diffusion. However, the controllability of the theoretical structure comes at the expenses of the realism of the model. For this, we discuss possible extensions and empirical applications.</p

Автобіографія Івана Багряного (з фондів ЦДАГО України)

Публікується автобіографія Івана Багряного, написана ним власноруч у січні 1944 р., напередодні еміграції за кордон.Публикуется автобиография Ивана Багряного, написанная им от руки в январе 1944 г., перед эмиграцией за рубеж.The is published the autobiography of Ivan Bagryanyi, he wrote in January 1944 before the emigration