Geo-cultural influences and critical factors in inter-firm collaboration

Inter-firm collaboration and other forms of inter-organisational activity are increasingly the means by which technological innovation occurs. This paper draws on evidence from two studies of the same set of firms to examine the conduct of collaborations over time across different contexts. The purpose is to examine the critical factors associated with successful collaboration and explore the importance of the geo-cultural context in understanding the conduct of inter-firm collaboration. The conceptual framework draws on two main sources: - Storper’s concept of ‘conventions’ of identity and participation and Lorenz’s classification of different types of knowledge. These are used to indicate the kinds and sources of adjustments required for successful collaboration

Polynomial Kernels for Weighted Problems

Kernelization is a formalization of efficient preprocessing for NP-hard problems using the framework of parameterized complexity. Among open problems in kernelization it has been asked many times whether there are deterministic polynomial kernelizations for Subset Sum and Knapsack when parameterized by the number $n$ of items. We answer both questions affirmatively by using an algorithm for compressing numbers due to Frank and Tardos (Combinatorica 1987). This result had been first used by Marx and V\'egh (ICALP 2013) in the context of kernelization. We further illustrate its applicability by giving polynomial kernels also for weighted versions of several well-studied parameterized problems. Furthermore, when parameterized by the different item sizes we obtain a polynomial kernelization for Subset Sum and an exponential kernelization for Knapsack. Finally, we also obtain kernelization results for polynomial integer programs

Dynamic dictionary matching and compressed suffix trees

Recent breakthrough in compressed indexing data structures has reduced the space for indexing a text (or a collection of texts) of length n from O(n log n) bits to O(n) bits, while allowing very efficient pattern matching. Yet the compressed nature of such indices also makes them difficult to update dynamically. This paper presents the first O(n)-bit representation of a suffix tree for a dynamic collection of texts whose total length is n, which supports insertion and deletion of a text T in O(|T| log2 n) time, as well as all suffix tree traversal operations, including forward and backward suffix links. This work can be regarded as a generalization of the compressed representation of static texts. Our new suffix tree representation serves as a core part in a compact solution for the dynamic dictionary matching problem, i.e., providing an O(d)-bit data structure for a dynamic collection of patterns of total length d that can support the dictionary matching query efficiently. When compared with the O(d log d)-bit suffix tree based solution of Amir et al., the compact solution increases the query time by roughly a factor of log d only. In the study of the above results, we also derive the first O(n)-bit representation for maintaining n pairs of balanced parentheses in O(log n/log log n) time per operation, matching the time complexity of the previous O(n log n)-bit solution.published_or_final_versio

Estimating the farm-level economic costs of spring cropping to manage Alopecurus myosuroides (black-grass) in UK agriculture

Crop rotation is a non-chemical strategy adopted by farmers to manage weeds. However not all crops in a rotation are equally profitable. Thus, there is potentially a trade-off between the costs and benefits of this strategy. The objective of the current study is to quantify this trade-off for the rotational control of an important weed (Alopecurus myosuroides). Data from 745 farms were used to parameterize a farm-level mixed-integer goal-programming model of the economics of spring cropping for weed control in UK agriculture. On average the short-term loss of profit from spring cropping is greater than the benefits in terms of reduced herbicide usage and yield increases. These costs are greater when weed densities are low, so that spring cropping is an expensive strategy in the early stages of an infestation. However, there is a great deal of farm-to-farm variation: factors such as soil type and farm size are important and the current study highlights that economic modelling at the farm level is important in enabling farmers to make informed decisions. In general, however, if spring cropping is to be a successful strategy then the benefits to farmers will be in terms of long-term reductions in weed densities, but this will be at the expense of short-term profitability

Crossing Paths with Hans Bodlaender:A Personal View on Cross-Composition for Sparsification Lower Bounds

On the occasion of Hans Bodlaender’s 60th birthday, I give a personal account of our history and work together on the technique of cross-composition for kernelization lower bounds. I present several simple new proofs for polynomial kernelization lower bounds using cross-composition, interlaced with personal anecdotes about my time as Hans’ PhD student at Utrecht University. Concretely, I will prove that Vertex Cover, Feedback Vertex Set, and the H-Factor problem for every graph H that has a connected component of at least three vertices, do not admit kernels of (formula presented) bits when parameterized by the number of vertices n for any (formula presented), unless (formula presented). These lower bounds are obtained by elementary gadget constructions, in particular avoiding the use of the Packing Lemma by Dell and van Melkebeek.</p

A comparative study of uniaxial pressure effects in intraband AlGaAs/GaAs and interband InAs/AlSb/GaSb resonant tunneling diodes

We report on the effects of uniaxial pressure on (001)-oriented AlGaAs/GaAs and InAs/AlSb/GaSb double barrier resonant tunneling diodes (RTDs). The current–voltage characteristics of the AlGaAs/GaAs RTDs shift asymmetrically due to stress-induced piezoelectric fields in the barriers and well structures. Although all the materials involved are piezoelectric, the interband InAs/AlSb/GaSb resonant tunneling device surprisingly shows, in contrast to the AlGaAs/GaAs one, a symmetrical behavior for the same orientation [110] of the applied pressure. We explain the observed differences considering the different tunneling paths involved in the conduction mechanism of the two heterostructure device types as well as their pressure dependencies. ©1998 American Institute of Physics.published_or_final_versio

Developing interventions to change recycling behaviors: A case study of applying behavioral science

The Theoretical Domains Framework (TDF) and the Behavior Change Wheel (BCW) are frameworks that can be used to develop recycling interventions. The aim of this study was to demonstrate the utility of these frameworks for developing recycling interventions. 20 semistructured interviews with university building users were analyzed using the TDF and BCW. Environmental context and resources, beliefs about consequences, knowledge, and intention were identified as the key theoretical domains influencing recycling behaviors. The BCW was used to develop recommendations for intervention. This research is the first case study to demonstrate how the TDF and the BCW can be used to develop recycling interventions

Advancing Workplace Diversity Through the Culturally Responsive Teamwork Framework.

Purpose Diversification of the profession is an important element of combating racism, bias, and prejudice in the speech-language pathology workforce at national and systemic levels. However, national and systemic change needs to be combined with equipping individual speech-language pathologists to adapt to the challenges that they face to engaging in culturally responsive practice. This paper presents four interacting levels of practice within the Culturally Responsive Teamwork Framework (CRTF): (a) intrapersonal practices, (b) interpersonal practices, (c) intraprofessional practices, and (d) the interprofessional practices. Conclusion CRTF is a practical, strengths-based framework that draws on international research and expertise to expand personal and professional practice and describe critical behaviors within the workplace that can be used to promote principles of evidence-based practice and social justice, especially when working with people from nondominant cultural or linguistic groups

General graviton exchange graph for four point functions in the AdS/CFT correspondence

In this note we explicitly compute the graviton exchange graph for scalar fields with arbitrary conformal dimension \Delta in arbitrary spacetime dimension d. This results in an analytical function in \Delta as well as in d.Comment: 14 pages, 2 figure