Artificial life techniques for load balancing in computational grids

Load balancing is a very important and complex problem in computational grids. A computational grid differs from traditional high performance computing systems in the heterogeneity of the computing nodes and communication links, as well as background workloads that may be present in the computing nodes. There is a need to develop algorithms that could capture this complexity yet can be easily implemented and used to solve a wide range of load balancing scenarios. Artificial life techniques have been used to solve a wide range of complex problems in recent times. The power of these techniques stems from their capability in searching large search spaces, which arise in many combinatorial optimization problems, very efficiently. This paper studies several well-known artificial life techniques to gauge their suitability for solving grid load balancing problems. Due to their popularity and robustness, a genetic algorithm (GA) and tabu search (TS) are used to solve the grid load balancing problem. The effectiveness of each algorithm is shown for a number of test problems, especially when prediction information is not fully accurate. Performance comparisons with Min-min, Max-min, and Sufferage are also discussed.     

Organisation as development coalition

The article provides a context for the discussion of development coalitions as a key feature of modern political and economic life. It traces the history of research programmes in work organisation over the past four decades, especially in North Western Europe, and challenges conventional views on the status of research in the social sciences.     

Service level agreements (SLAs) parameter negotiation between heterogeneous 4G wireless network operators

We are currently witnessing a growing interest of network operators to migrate their existing 2G/3G networks to 4G technologies such as long-term evolution (LTE) to enhance the user experience and service opportunities in terms of providing multi-megabit bandwidth, more efficient use of radio networks, latency reduction, and improved mobility. Along with this, there is a strong deployment of packet data networks such as those based on IEEE 802.11 and 802.16 standards. Mobile devices are having increased capabilities to access many of these wireless networks types at the same time. Reinforcing quality of service (QoS) in 4G wireless networks will be a major challenge because of varying bit rates, channel characteristics, bandwidth allocation and global roaming support among heterogeneous wireless networks. As a mobile user moves across access networks, to the issue of mapping resource reservations between different networks to maintain QoS behavior becomes crucial. To support global roaming and interoperability across heterogeneous wireless networks, it is important for wireless network operators to negotiate service level agreement (SLA) contracts relevant to the QoS requirements. Wireless IP traffic modeling (in terms of providing assured QoS) is still immature because the majority of the existing work is merely based on the characterization of wireless IP traffic without investigating the behavior of queueing systems for such traffic. To overcome such limitations, we investigate SLA parameter negotiation among heterogeneous wireless network operators by focusing on traffic engineering and QoS together for 4G wireless networks. We present a novel mechanism that achieves service continuity through SLA parameter negotiation by using a translation matrix, which maps QoS parameters between different access networks. The SLA matrix composition is modeled analytically based on the G/M/1 queueing system. We evaluate the model using two different scheduling schemes and we derive closed form expressions for different QoS parameters for performance metrics such as packet delay and packet loss rate. We also develop a discrete event simulator and conduct a series of simulation experiments in order to understand the QoS behavior of corresponding traffic classes.     

Attachment style.

This article provides a brief review of attachment theory and recent research studies on its implications for individual psychotherapy. Attachment theory offers a conceptual framework that helps illuminate how past experiences with caregivers might influence current transactions between therapist and patient. Both patients and therapists may form internal working models that are based, in part, on early experiences of interpersonal responsiveness. Such working models are reflected in secure, anxious-ambivalent, and anxious-avoidant attachment styles, which describe whether patients (and therapists) tend to be comfortable and confident in relationships, fearful of abandonment, or defensively separate. Recent studies showed that attachment styles in the context of therapy can be measured reliably and related to therapeutic process (e.g., the alliance) and outcome (e.g., treatment response). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A combinatorial library of an {alpha}-helical bacterial receptor domain

The construction and characterization of a combinatorial libraryof a solvent-exposed surface of an -helical domain derived froma bacterial receptor is described. Using a novel solid-phaseapproach, the library was assembled in a directed and successivemanner utilizing single-stranded oligonucleotides containingmultiple random substitutions for the variegated segments ofthe gene fragment The simultaneous substitution of 13 residuesto all 20 possible amino acids was carried out in a region spanning81 nucleotides. The randomization was made in codons for aminoacids that were modelled to be solvent accessible at a surfacemade up from two of the three a-helices of a monovalent Fc-bindingdomain of staphylococcal protein A. After cloning of the PCR-amplifiedlibrary into a phagemid vector adapted for phage display ofthe mutants, DNA sequencing analysis suggested a random distributionof codons in the mutagenized positions. Four members of thelibrary with multiple substitutions were produced in Escherichiacoli as fusions to an albumin-binding affinity tag derived fromstreptococcal protein G. The fusion proteins were purified byhuman serum albumin affinity chromatography and subsequentlycharacterized by SDSelectrophoresis, CD spectroscopy and biosensoranalysis. The analyses showed that the mutant protein A derivativescould all be secreted as soluble full-length proteins. Furthermore,the CD analysis showed that all mutants, except one with a prolineintroduced into helix 2, have secondary structures in closeagreement with the wild-type domain. These results proved thatmembers of this -helical receptor library with multiple substitutionsin the solvent-exposed surface remain stable and soluble inE.coli. The possibility of using this library for a phenotypicselection strategy to obtain artificial antibodies with novelfunctions is discussed.     

RETT-gen: A globally efficient routing protocol for wireless sensor networks by equalising sensor energy and avoiding energy holes

Wireless sensor networks are composed of a large number of sensor nodes with limited energy resources. Once deployed, the sensor nodes are usually inaccessible to the user, and thus replacement of the energy resource is not feasible. Hence, energy efficiency is a key design issue that needs to be enhanced in order to improve the life span of the entire network. Several routing protocols have been proposed to improve the effective lifetime of the network with limited energy supply. In this paper, we propose routing based on energy–temperature transformation, RETT-gen, a scalable energy-efficient clustering and routing protocol designed for wireless sensor networks. The main goal of RETT-gen is to evenly distribute the energy load among all the sensor nodes in the network so that there are no overly-utilized sensor nodes that will run out of energy before the others. To achieve this goal, RETT-gen uses heat conductivity as a metaphor and uses the heat dissipation difference equations. In RETT-gen, we transform the expected lifetime of each sensor node to an equivalent temperature, and then by using the heat dissipation equations, we find the hottest path for sending data to the base station, which will not always be the shortest path. We evaluate the performance of the RETT-gen protocol via simulations, and compare it to the performance of well-known routing protocols (i.e. LEACH [W. Heinzelman, A. Chandrakasan, H. Balakrishnan, Energy-efficient communication protocol for wireless microsensor networks, in: Proceedings of the 33rd Hawaii International Conference on System Sciences (HICSS’00), 2000.] and EEUC [C. Li, M. Ye, G. Chen, J. Wu, An energy-efficient unequal clustering mechanism for wireless sensor networks, in: Proceedings of the International IEEE Conference on Mobile Adhoc and Sensor Systems (MASS), 2005.]). Simulation results show that by equalizing the sensor nodes energy, RETT-gen insures that the lifetime of the entire sensor network is maximized, the connectivity in a sensor network is maintained for as long as possible, and that the residual energy of the entire network is of the same order.     

Monitoring Assisted Robust Routing in Wireless Mesh Networks

In this paper, we present a monitoring assisted robust routing scheme for wireless mesh networks which exploits the broadcast nature of wireless transmissions at special routers with added monitoring functionalities. These routers passively listen to the transmissions in their neighborhood and compare the routing behavior against the routing state collectively maintained by them. If any inconsistency is found, as a result of software/hardware malfunction, these routers try to determine the node causing it and recover from it in a timely fashion. The scheme is developed for wireless mesh networks where the communication overhead is a critical issue. The performance evaluation of our scheme shows considerable improvement in reliability (i.e., delivery ratio achieved by standard routing protocols) with minimal overhead under situations of malfunctions.     

An Efficient Memory Organization for High-ILP Inner Modem Baseband SDR Processors

This paper presents a memory organization for SDR inner modem baseband processors that focus on exploiting ILP. This memory organization uses power-efficient, single-ported, interleaved scratch-pad memory banks to provide enough bandwidth to a high-ILP processors. A system of queues in the memory interface is used to resolve bank conflicts among the single-ported banks, and to spread long bursts of conflicting accesses to the same bank over time. Bank address rotation is used to spread long bursts of conflicting accesses over multiple banks. All proposed techniques have been implemented in hardware, and are evaluated for a number of different wireless communication standards. For the 11a|n benchmarks, the overhead of stall cycles resulting from unresolved bank conflicts can be reduced to below 2% with the proposed organization. For 3GPP-LTE, the most demanding wireless standard we evaluated, the overhead is reduced to less than 0.13%. This is achieved with little energy and area overhead, and without any bank-aware compiler support.     

Sustainability priorities across the strategic and operational level in packaging development

Sustainability is well‐established in many companies' strategic postures. However, executing sustainability‐related goals often lags at the operational level. This study analyses how decision‐making processes in packaging development at different hierarchical levels are characterized in achieving a sustainability consensus. This research focuses on the alignment of the strategic and operational levels of packaging development in relation to the integration of sustainability considerations. This materializes in a stakeholder perspective on packaging development and an analysis of targets aiming for the integration of sustainability considerations in such development processes. The involvement and decision making by internal stakeholders, the involvement of external stakeholders and sustainability target setting are considered as conditions causing the outcome of interest: levels of sustainability implementation on both the strategic and the operational levels of packaging development. By using a set‐theoretic method, we address that different compositions of stakeholder involvement and target setting might cause the same level of sustainability priority at the strategic and operational levels. For data analysis, we use a fuzzy‐set qualitative comparative analysis (fsQCA) with empirical data derived from survey responses by packaging experts. This approach is motivated by its ability to address the complexity of the interplay of case characteristics within development processes. The research findings provide several indications of a limited alignment of a company's strategic sustainability ambition with the operational activities of multidisciplinary packaging development teams. The insights on the sustainability‐related configurations of stakeholders and target setting provide guidance for managing projects across the strategic and operational levels in improving sustainable packaging development.