Productivity, Multinationals and Knowledge Spillovers: Evidence from the UK Retail Sector

This paper discusses the impact of foreign-ownership presence on the productivity performance of domestically-owned British retailers. In specific, we investigate the existence of productivity spillovers in the form of knowledge transfer. To guide our estimations, we develop a simple Hotelling model in which we show how the transfer of operational knowledge from MNE to non-MNE retailers, may result to an increase in the productivity of the latter and increased economic activity in the regions with relatively higher concentration of foreign investment. Our empirical estimations lend support to the assumptions upon which the theoretical model is built, while confirming the positive and highly significant impact of these spillovers on the productivity performance of domestic firms. More specifically, using data from the Annual Respondent Dataset (ARD), we find that positive spillovers exist but are mostly confined to the region in which foreign subsidiaries locate. Furthermore, the productivity benefit from regional FDI spillovers increases with the absorptive capacity of domestic retailers.FDI; Multinationals; Productivity; Retailing; Spillovers

Efficient Proactive Caching for Supporting Seamless Mobility

We present a distributed proactive caching approach that exploits user mobility information to decide where to proactively cache data to support seamless mobility, while efficiently utilizing cache storage using a congestion pricing scheme. The proposed approach is applicable to the case where objects have different sizes and to a two-level cache hierarchy, for both of which the proactive caching problem is hard. Additionally, our modeling framework considers the case where the delay is independent of the requested data object size and the case where the delay is a function of the object size. Our evaluation results show how various system parameters influence the delay gains of the proposed approach, which achieves robust and good performance relative to an oracle and an optimal scheme for a flat cache structure.Comment: 10 pages, 9 figure

A Networked Hybrid Interface for Audience Sonification and Machine Learning

Lick the Toad is an ongoing project developed as a web based interface that runs in modern browsers. It provides a custom made platform to collect user data accessed from mobile devices, such as smartphones, tablets etc. The system offers a tool for interactive collective sonification supporting networked music performance. It can be used in various contexts, such as an onsite installation, or for the distribution of raw data for live coding performances making it a versatile component for an array of creative practices. Of these, live coding which is one of the author's artistic approach to create live performances is demonstrated in this article highlighting and elaborating on technical and musical aspects of this approach. Final sections outline the system as a tool for live coding performances and cover a series of potential interactions integrating audience and/or using it independently alike

On Optimal and Fair Service Allocation in Mobile Cloud Computing

This paper studies the optimal and fair service allocation for a variety of mobile applications (single or group and collaborative mobile applications) in mobile cloud computing. We exploit the observation that using tiered clouds, i.e. clouds at multiple levels (local and public) can increase the performance and scalability of mobile applications. We proposed a novel framework to model mobile applications as a location-time workflows (LTW) of tasks; here users mobility patterns are translated to mobile service usage patterns. We show that an optimal mapping of LTWs to tiered cloud resources considering multiple QoS goals such application delay, device power consumption and user cost/price is an NP-hard problem for both single and group-based applications. We propose an efficient heuristic algorithm called MuSIC that is able to perform well (73% of optimal, 30% better than simple strategies), and scale well to a large number of users while ensuring high mobile application QoS. We evaluate MuSIC and the 2-tier mobile cloud approach via implementation (on real world clouds) and extensive simulations using rich mobile applications like intensive signal processing, video streaming and multimedia file sharing applications. Our experimental and simulation results indicate that MuSIC supports scalable operation (100+ concurrent users executing complex workflows) while improving QoS. We observe about 25% lower delays and power (under fixed price constraints) and about 35% decrease in price (considering fixed delay) in comparison to only using the public cloud. Our studies also show that MuSIC performs quite well under different mobility patterns, e.g. random waypoint and Manhattan models

Frequency Domain Hybrid-ARQ Chase Combining for Broadband MIMO CDMA Systems

In this paper, we consider high-speed wireless packet access using code division multiple access (CDMA) and multiple-input multiple-output (MIMO). Current wireless standards, such as high speed packet access (HSPA), have adopted multi-code transmission and hybrid-automatic repeat request (ARQ) as major technologies for delivering high data rates. The key technique in hybrid-ARQ, is that erroneous data packets are kept in the receiver to detect/decode retransmitted ones. This strategy is refereed to as packet combining. In CDMA MIMO-based wireless packet access, multi-code transmission suffers from severe performance degradation due to the loss of code orthogonality caused by both interchip interference (ICI) and co-antenna interference (CAI). This limitation results in large transmission delays when an ARQ mechanism is used in the link layer. In this paper, we investigate efficient minimum mean square error (MMSE) frequency domain equalization (FDE)-based iterative (turbo) packet combining for cyclic prefix (CP)-CDMA MIMO with Chase-type ARQ. We introduce two turbo packet combining schemes: i) In the first scheme, namely "chip-level turbo packet combining", MMSE FDE and packet combining are jointly performed at the chip-level. ii) In the second scheme, namely "symbol-level turbo packet combining", chip-level MMSE FDE and despreading are separately carried out for each transmission, then packet combining is performed at the level of the soft demapper. The computational complexity and memory requirements of both techniques are quite insensitive to the ARQ delay, i.e., maximum number of ARQ rounds. The throughput is evaluated for some representative antenna configurations and load factors to show the gains offered by the proposed techniques.Comment: Submitted to IEEE Transactions on Vehicular Technology (Apr 2009