bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantum measurements in continuous time, non-Markovian evolutions and feedback
Authors: Barchielli Alberto , Gregoratti Matteo
Published: October 2012

In this article, we reconsider a version of quantum trajectory theory based on the stochastic Schrödinger equation with stochastic coefficients, which was mathematically introduced in the 1990s, and we develop it in order to describe the non-Markovian evolution of a quantum system continuously measured and controlled, thanks to a measurement-based feedback. Indeed, realistic descriptions of a feedback loop have to include delay and thus need a non-Markovian theory. The theory allows us to put together non-Markovian evolutions and measurements in continuous time, in agreement with the modern axiomatic formulation of quantum mechanics. To illustrate the possibilities of such a theory, we apply it to a two-level atom stimulated by a laser. We introduce closed loop control too, via the stimulating laser, with the aim of enhancing the ‘squeezing’ of the emitted light, or other typical quantum properties. Note that here we change the point of view with respect to the usual applications of control theory. In our model, the ‘system’ is the two-level atom, but we do not want to control its state, to bring the atom to a final target state. Our aim is to control the ‘MandelQ-parameter’ and the spectrum of the emitted light; in particular, the spectrum is not a property at a single time, but involves a long interval of times (a Fourier transform of the autocorrelation function of the observed output is needed).
On structure-preserving transformations of the Itō generator matrix for model reduction of quantum feedback networks
Authors: Nurdin Hendra I. , Gough John E.
Published: October 2012

Two standard operations of model reduction for quantum feedback networks, elimination of internal connections under the instantaneous feedback limit and adiabatic elimination of fast degrees of freedom, are cast as structure-preserving transformations of Itō generator matrices. It is shown that the order in which they are applied is inconsequential.
Asymptotic inference in system identification for the atom maser
Authors: Cătană Cătălin , van Horssen Merlijn , Guţă Mădălin
Published: October 2012

System identification is closely related to control theory and plays an increasing role in quantum engineering. In the quantum set-up, system identification is usually equated to process tomography, i.e. estimating a channel by probing it repeatedly with different input states. However, for quantum dynamical systems such as quantum Markov processes, it is more natural to consider the estimation based on continuous measurements of the output, with a given input that may be stationary. We address this problem using asymptotic statistics tools, for the specific example of estimating the Rabi frequency of an atom maser. We compute the Fisher information of different measurement processes as well as the quantum Fisher information of the atom maser, and establish the local asymptotic normality of these statistical models. The statistical notions can be expressed in terms of spectral properties of certain deformed Markov generators, and the connection to large deviations is briefly discussed.
Emergent phenomena at multiferroic heterointerfaces
Authors: Yu P. , Chu Y. H. , Ramesh R.
Published: October 2012

The coupling and reconstruction of electronic degrees of freedom (such as charge, spin and orbital) at a heterointerface can lead to unexpected and exotic states of matter. In this study, using model systems consisting of multiferroic BiFeO
3
and ferromagnetic La
0.7
Sr
0.3
MnO
3
, we review the current understanding of a novel interfacial magnetic state formed at the interface, and highlight some possible mechanisms responsible for this interesting phenomenon and identify open questions for future studies.
Towards electrical spin injection into LaAlO
3
–SrTiO
3
Authors: Bibes M. , Reyren N. , Lesne E. , George J.-M. , Deranlot C. , Collin S. , Barthélémy A. , Jaffrès H.
Published: October 2012

Future spintronics devices will be built from elemental blocks allowing the electrical injection, propagation, manipulation and detection of spin-based information. Owing to their remarkable multi-functional and strongly correlated character, oxide materials already provide such building blocks for charge-based devices such as ferroelectric field-effect transistors (FETs), as well as for spin-based two-terminal devices such as magnetic tunnel junctions, with giant responses in both cases. Until now, the lack of suitable channel materials and the uncertainty of spin-injection conditions in these compounds had however prevented the exploration of similar giant responses in oxide-based lateral spin transport structures. In this paper, we discuss the potential of oxide-based spin FETs and report magnetotransport data that suggest electrical spin injection into the LaAlO
3
–SrTiO
3
interface system. In a local, three-terminal measurement scheme, we analyse the voltage variation associated with the precession of the injected spin accumulation driven by perpendicular or longitudinal magnetic fields (Hanle and ‘inverted’ Hanle effects). The spin accumulation signal appears to be much larger than expected, probably owing to amplification effects by resonant tunnelling through localized states in the LaAlO
3
. We give perspectives on how to achieve direct spin injection with increased detection efficiency, as well on the implementation of efficient top gating schemes for spin manipulation.
Termination control of electronic phases in oxide thin films and interfaces: LaAlO
3
/SrTiO
3
(001)
Authors: Pentcheva R. , Arras R. , Otte K. , Ruiz V. G. , Pickett W. E.
Published: October 2012

A wealth of intriguing properties emerge in the seemingly simple system composed of the band insulators LaAlO
3
and SrTiO
3
such as a two-dimensional electron gas, superconductivity and magnetism. In this paper, we review the current insight obtained from first principles calculations on the mechanisms governing the behaviour of thin LaAlO
3
films on SrTiO
3
(001). In particular, we explore the strong dependence of the electronic properties on the surface and interface termination, the finite film thickness, lattice polarization and defects. A further aspect that is addressed is how the electronic behaviour and functionality can be tuned by an SrTiO
3
capping layer, adsorbates and metallic contacts. Lastly, we discuss recent reports on the coexistence of magnetism and superconductivity in this system for what they might imply about the electronic structure of this system.
Magnetoelectric interfaces and spin transport
Authors: Burton J. D. , Tsymbal E. Y.
Published: October 2012

Engineered heterostructures designed for electric control of magnetic properties, the so-called
magnetoelectric interfaces
, present a novel route towards using the spin degree of freedom in electronic devices. Here, we review how a subset of such interfaces, namely ferromagnet–ferroelectric heterostructures, display electronically mediated control of magnetism and, in particular, emphasis is placed on how these effects manifest themselves as detectable spin-dependent transport phenomena. Examples of these effects are given for a variety of material systems on the basis of ferroelectric oxides, manganese and ruthenium magnetic complex oxides and elemental ferromagnetic metals. Results from both theory and experiment are discussed.
Advances to Electrode Pullback in Cochlear Implant Surgery
Authors: Todt Ingo , Basta Dietmar , Seidl Rainer , Ernst Arne
Published: October 2012

Objective. To observe the intracochlear behavior of a cochlear implant electrode insertion technique (called “pullback”) in temporal bones.Study Design. Experimental.Settings. Tertiary referral center.Method. The change of the intracochlear electrode position was investigated under various conditions of an electrode pullback (N=54) in 9 radiologically, size-estimated temporal bones (TBs). Those TBs were prepared by removal of the cochlear scalar roof to apply digital video capture procedures to monitor the pullback procedures. The digitally captured pictures were analyzed with specific software.Results. An optimal pullback of the electrode varied between 1.37 mm and 2.67 mm. While a limited pullback is without risk, an extended pullback bears the risk of removing the electrode tip out of its initial position or out of the cochlea. A correlation between cochlear size and the amount of pullback was not found.Conclusion. An initial insertion to the first or the second marker on the electrode followed by a limited pullback of about 1.37 mm to 1.5 mm can be recommended to achieve an optimized perimodiolar position. A pullback of up to two marker positions bears the risk of removing the electrode tip out of its initial position.
Sulfonate pseudohalides of boron subphthalocyanine
Authors: Paton Andrew S. , Lough Alan J. , Bender Timothy P.
Published: October 2012

The crystal structures of three sulfonate pseudohalide derivatives of boron subphthalocyanine (BsubPc) are described and compared with four structures of three published sulfonate derivatives. Benzenesulfonate boron subphthalocyanine [(benzenesulfonato)(subphthalocyaninato)boron, C30H17BN6O3S, (I)] crystallizes in the space groupP\overline{1} withZ= 2. The structure contains two centrosymmetric π-stacking interactions between the concave faces of the isoindoline units in the BsubPc ligands. 3-Nitrobenzenesulfonate boron subphthalocyanine [(3-nitrobenzenesulfonato)(subphthalocyaninato)boron, C30H16BN7O5S, (II)] crystallizes in the space groupP21/cwithZ= 4. The structure contains an intermolecular S—O...π interaction from the sulfonate group to a five-membered N-containing ring of an isoindoline unit on the concave side of a neighbouring BsubPc ligand, at a distance of 3.151 (3) Å. The crystal of methanesulfonate boron subphthalocyanine [(methanesulfonato)(subphthalocyaninato)boron, C25H15BN6O3S, (III)] was producedviasublimation and it is not a solvate, in contrast with two previously published structures of the same compound. Compound (III) crystallizes in the space groupP21/nwithZ = 2, and its structure is similar to that of the more common compound Cl-BsubPc.
Structures of haemoglobin from woolly mammoth in liganded and unliganded states
Authors: Noguchi Hiroki , Campbell Kevin L. , Ho Chien , Unzai Satoru , Park Sam-Yong , Tame Jeremy R. H.
Published: October 2012

The haemoglobin (Hb) of the extinct woolly mammoth has been recreated using recombinant genes expressed inEscherichia coli. The globin gene sequences were previously determined using DNA recovered from frozen cadavers. Although highly similar to the Hb of existing elephants, the woolly mammoth protein shows rather different responses to chloride ions and temperature. In particular, the heat of oxygenation is found to be much lower in mammoth Hb, which appears to be an adaptation to the harsh high-latitude climates of the Pleistocene Ice Ages and has been linked to heightened sensitivity of the mammoth protein to protons, chloride ions and organic phosphates relative to that of Asian elephants. To elucidate the structural basis for the altered homotropic and heterotropic effects, the crystal structures of mammoth Hb have been determined in the deoxy, carbonmonoxy and aquo-met forms. These models, which are the first structures of Hb from an extinct species, show many features reminiscent of human Hb, but underline how the delicate control of oxygen affinity relies on much more than simple overall quaternary-structure changes.
Structural insights into the broadened substrate profile of the extended-spectrum β-lactamase OXY-1-1 fromKlebsiella oxytoca
Authors: Liang Yu-He , Gao Rong , Su Xiao-Dong
Published: October 2012

Klebsiella oxytocais a pathogen that causes serious infections in hospital patients. It shows resistance to many clinically used β-lactam antibiotics by producing chromosomally encoded OXY-family β-lactamases. Here, the crystal structure of an OXY-family β-lactamase, OXY-1-1, determined at 1.93 Å resolution is reported. The structure shows that the OXY-1-1 β-lactamase has a typical class A β-lactamase fold and exhibits greater similarity to CTX-M-type β-lactamases than to TEM-family or SHV-family β-lactamases. It is also shown that the enzyme provides more space around the active cavity for theR1andR2substituents of β-lactam antibiotics. The half-positive/half-negative distribution of surface electrostatic potential in the substrate-binding pocket indicates the preferred properties of substrates or inhibitors of the enzyme. The results reported here provide a structural basis for the broadened substrate profile of the OXY-family β-lactamases.
Error-estimation-guided rebuilding ofde novomodels increases the success rate ofab initiophasing
Authors: Shrestha Rojan , Simoncini David , Zhang Kam Y. J.
Published: October 2012

Recent advancements in computational methods for protein-structure prediction have made it possible to generate the high-qualityde novomodels required forab initiophasing of crystallographic diffraction data using molecular replacement. Despite those encouraging achievements inab initiophasing usingde novomodels, its success is limited only to those targets for which high-qualityde novomodels can be generated. In order to increase the scope of targets to whichab initiophasing withde novomodels can be successfully applied, it is necessary to reduce the errors in thede novomodels that are used as templates for molecular replacement. Here, an approach is introduced that can identify and rebuild the residues with larger errors, which subsequently reduces the overall Cαroot-mean-square deviation (CA-RMSD) from the native protein structure. The error in a predicted model is estimated from the average pairwise geometric distance per residue computed among selected lowest energy coarse-grained models. This score is subsequently employed to guide a rebuilding process that focuses on more error-prone residues in the coarse-grained models. This rebuilding methodology has been tested on ten protein targets that were unsuccessful using previous methods. The average CA-RMSD of the coarse-grained models was improved from 4.93 to 4.06 Å. For those models with CA-RMSD less than 3.0 Å, the average CA-RMSD was improved from 3.38 to 2.60 Å. These rebuilt coarse-grained models were then converted into all-atom models and refined to produce improvedde novomodels for molecular replacement. Seven diffraction data sets were successfully phased using rebuiltde novomodels, indicating the improved quality of these rebuiltde novomodels and the effectiveness of the rebuilding process. Software implementing this method, calledMORPHEUS, can be downloaded from http://www.riken.jp/zhangiru/software.html.
Structure of the corrinoid:coenzyme M methyltransferase MtaA fromMethanosarcina mazei
Authors: Hoeppner Astrid , Thomas Frank , Rueppel Alma , Hensel Reinhard , Blankenfeldt Wulf , Bayer Peter , Faust Annette
Published: October 2012

The zinc-containing corrinoid:coenzyme M methyltransferase MtaA is part of the methanol–coenzyme M–methyltransferase complex ofMethanosarcina mazei. The whole complex consists of three subunits: MtaA, MtaB and MtaC. The MtaB–MtaC complex catalyses the cleavage of methanol (bound to MtaB) and the transfer of the methyl group onto the cobalt of cob(I)alamin (bound to MtaC). The MtaA–MtaC complex catalyses methyl transfer from methyl-cob(III)alamin (bound to MtaC) to coenzyme M (bound to MtaA). The crystal structure of the MtaB–MtaC complex fromM. barkerihas previously been determined. Here, the crystal structures of MtaA fromM. mazeiin a substrate-free but Zn2+-bound state and in complex with Zn2+and coenzyme M (HS-CoM) are reported at resolutions of 1.8 and 2.1 Å, respectively. A search for homologous proteins revealed that MtaA exhibits 23% sequence identity to human uroporphyrinogen III decarboxylase, which has also the highest structural similarity (r.m.s.d. of 2.03 Å for 306 aligned amino acids). The main structural feature of MtaA is a TIM-barrel-like fold, which is also found in all other zinc enzymes that catalyse thiol-group alkylation. The active site of MtaA is situated at the narrow bottom of a funnel such that the thiolate group of HS-CoM points towards the Zn2+ion. The Zn2+ion in the active site of MtaA is coordinated tetrahedrallyviaHis240, Cys242 and Cys319. In the substrate-free form the fourth ligand is Glu263. Binding of HS-CoM leads to exchange of the O-ligand of Glu263 for the S-ligand of HS-CoM with inversion of the zinc geometry. The interface between MtaA and MtaC for transfer of the methyl group from MtaC-bound methylcobalamin is most likely to be formed by the core complex of MtaB–MtaC and the N-terminal segment (a long loop containing three α-helices and a β-hairpin) of MtaA, which is not part of the TIM-barrel core structure of MtaA.
The SURE program and incentives for crop insurance participation
Authors: Bekkerman Anton , Smith Vincent H. , Watts Myles J.
Published: October 2012

Purpose

The aim of this paper is to show how provisions of the Supplemental Revenue Assistance Payments (SURE) program impacts production practices, and empirically examine changes in crop insurance participation rates as a means of measuring producer responses to the program.

Design/methodology/approach

The structure of the SURE program is described and a stylized theoretical model is used to show the SURE program's effects on farm‐level crop insurance and production decisions. A county‐level cross‐sectional empirical specification with regional fixed effects is used to test the hypothesis that producers who are most likely to benefit from production practice re‐optimization are more likely to participate in crop insurance.

Findings

Results from empirical analyses of corn, soybean, and wheat production areas show that the SURE program has had substantial impacts on crop insurance participation by producers who are more likely to receive SURE indemnities and exploit moral hazard opportunities.

Research limitations/implications

Because the program has only recently been introduced, empirical estimates of the program's long‐run impacts are not estimable.

Practical implications

Results indicate that the program can have unexpected market consequences, with increased frequency and size of SURE indemnity claims than the Congressional Budget Office anticipated and increases in aggregate tax payer subsidies for both the crop insurance and SURE program. These outcomes can have important implications on motivating a restructuring of the program in the next farm bill.

Social implications

Increased tax payer expenditures on the SURE and crop insurance programs in the form of subsidies can lead to non‐trivial reductions in social welfare.

Originality/value

This research is the first to develop a rigorous model of the SURE program's impacts on producer responses and associated effects on crop insurance participation. The study also provides empirical evidence of these effects.
The convenience consumer's dilemma
Authors: Veflen Olsen Nina
Published: October 2012

Purpose

The overall aim of this research is to increase understanding of consumers' barriers in relation to convenience food. While the motivation for consuming convenience food has been investigated frequently, few studies have investigated the barriers.

Design/methodology/approach

Three focus group studies, exploring consumers' ready‐to‐heat (RTH) meal dilemmas, were conducted in Norway.

Findings

The frequency of barriers and four narratives are presented, and the results indicate that consumers face bottom‐up dilemmas related to barriers like sensory perception, health, economy, and managing relationships; and/or top‐down value dilemmas related to traditions, quality of life and environmental barriers when considering convenience food consumption.

Research limitations/implications

This research contributes to the current body of literature, which mainly focuses on drivers of convenience demand, by elaborating on barriers and dilemmas for convenience choice.

Practical implications

The findings imply how marketers should communicate with the convenience market. Marketing managers need to understand which barriers to break or what dilemmas to discuss when communicating with the RTH market.

Originality/value

By structuring focus group interviews according to the individual respondents (“who said what”) and by presenting the data as narratives, the paper shows a new way to analyze focus group interviews.
Food sector SMEs and innovation types
Authors: Baregheh Anahita , Rowley Jennifer , Sambrook Sally , Davies Dafydd
Published: October 2012

Purpose

This article aims to offer insights into the range of innovations in food sector SMEs, and demonstrate the way in which managers classify their innovations on the basis of Francis and Bessant's classification of innovations into the following four types: product, process, position, and paradigm.

Design/methodology/approach

As part of a larger questionnaire‐based survey on innovation in food sector SMEs, respondents were asked to provide examples of their recent innovations and to categorise them as product, process, position, or paradigm innovations.

Findings

Food sector SMEs offered a wide range of examples of innovation. They were able to classify their innovations into product, process, position or paradigm innovations. Further, there is evidence that food sector SMEs are engaged in a range of innovation types, although a greater number of examples were offered for product innovation than for other types of innovation. Additionally, there is evidence of overlap and complementariness between different types of innovation.

Originality/value

Although the food sector plays an important role within the UK economy, innovation in food and drink sector SMEs has received relatively limited attention. This article offers interesting insights into the reality of innovation in food sector SMEs. In addition, it demonstrates the applicability of Francis and Bessant's model of types of innovation to SMEs in this sector.
Knowledge management and open access e‐theses: Indian initiatives
Authors: Sheeja N.K.
Published: October 2012

Purpose

This paper aims to describe recent developments in the services provided by Indian electronic thesis and dissertation (ETD) repositories. It seeks to explore the prospect of knowledge formation and diffusion in India and to discuss the potential of open access e‐theses repositories for knowledge management.

Design/methodology/approach

This study is based on literature review and content analysis of Indian ETD repository websites. Institutional repositories and electronic thesis and dissertation projects in India were identified through a literature survey as well as internet searching and browsing. The study examines the tools, type of contents, coverage and aims of Indian ETD repositories.

Findings

The paper acknowledges the need for knowledge management for national development. It highlights the significance of an integrated platform for preserving, searching and retrieving Indian theses. It describes the features and functions of Indian ETD repositories.

Originality/value

The paper provides insights into the characteristics of the national repository of ETDs of India, which encourage and support open access to publicly‐funded research.
Recycling attitude and behaviour in university campus: a case study in Hong Kong
Authors: Wan Calvin , Cheung Ronnie , Qiping Shen Geoffrey
Published: October 2012

Purpose

This study investigates the recycling attitudes and behaviour of university students and staff members, and suggests ways to improve environmental policies and recycling facilities in a university campus.

Design/methodology/approach

This study applies the theory of planned behaviour, through which it develops an instrument to measure the determinants of recycling behaviour among the people in a university campus. A survey was designed and administered at a public university in Hong Kong; 205 valid responses from 179 students and 26 staff members were collected. A partial least squares approach was used to validate the proposed model. This model accounted for the 42.1 per cent and 50.3 per cent variance (R2) in behavioural intention and behaviour, respectively, vis‐à‐vis recycling activities.

Findings

The survey results suggested that behavioural intention with regard to recycling is influenced by attitude, the subjective norms, perceived behavioural control, awareness of consequences, the moral norms, and convenience. Educational and promotional programmes highlighting the benefits and importance of recycling activities and convenience of the recycling facilities can be adopted as the key strategies to encourage recycling on campus.

Research limitations/implications

The unique culture in relation to recycling in the specific campus environment and the nature of the sample might limit the generalisability of the results to other areas and contexts. The self‐report‐based measures adopted in this study might lead to a social desirability bias in the results provided by the respondents.

Originality/value

The findings provide insightful information for universities and the wider community to shape a more user‐friendly and convenient recycling scheme. This can fulfil the actors' social responsibility.
A framework for the evaluation of turnaround maintenance projects
Authors: Obiajunwa Christopher C.
Published: October 2012

Purpose

The aim of this study is to establish a framework with which process plants can evaluate the performance of their turnaround maintenance (TAM) projects at the end of the event without making reference to previous events.

Design/methodology/approach

This is a case study. The study involved the case studies of six process plants in the UK. Three sources of evidence were used in this study including; interviews, direct observation and official documents.

Findings

The case studies show that TAM projects can be evaluated by assessment of the management performance and the resultant benefits realised. The uses of generic project success measures are not very adequate for TAM.

Practical Implications

The study developed success measurement criteria for TAM projects. Instead of comparing performance of TAM projects with previous ones to assess how successful the outcome is, organisations can evaluate their TAM project's performance based on the current TAM using the criteria developed in the framework. In addition, these success criteria will enable the organisation to evaluate the benefits expected from the TAM project outcome at hand‐over of the plant from the TAM project management to the operations management.

Originality/value

Operators of process plants and hence engineering facilities still measure the outcome of TAM using measures that are generic for EPC projects. Considering the peculiar nature of TAM, this study has developed success measurement criteria for TAM projects specifically.
Preventive maintenance planning using group technology
Authors: Almomani Mohammed , Abdelhadi Abdelhakim , Seifoddini Hamid , Xiaohang Yue
Published: October 2012

Purpose

The purpose of this paper is to develop a preventive maintenance (PM) model that encounters the problems of traditional methods of conducting PM within high component/machine variety environments.

Design/methodology/approach

A new platform to conduct planning of the PM actions by using clustering based on the Group Technology concept to create PM virtual cells of equipment/machines is introduced. A real case study at Arab Potash Company was used to illustrate the model. The component/machine variety that requires PM at the considered company is in thousands of items.

Findings

PM for high component/machine environments are not enough addressed in the literature. The concept of clustering and similarity coefficient was used and found very useful to model this situation.

Practical implications

The proposed procedure will assist maintenance managers/engineers in too many ways. It will help to optimize the inventory of the spare parts, and to create standard process plan for executing the preventive maintenance operation.

Originality/value

This paper presents a new procedure to implement preventive maintenance in high component/machine environments using clustering technique concept. Models that address this concept are rare and very limited in the literature.
Distribution network rationalisation through benchmarking with DEA
Authors: Hung Lau Kwok
Published: October 2012

Purpose

The purpose of this paper is to discuss the use of data envelopment analysis (DEA) to benchmark store performance for the purpose of rationalising retail distribution network.

Design/methodology/approach

As an illustration of the approach, DEA is applied to a sample of front stores of a major retailer in Australia to compare their relative efficiency in distribution. Together with other techniques such as customer segmentation and spatial distribution of demand, this paper shows that DEA can provide an objective basis for distribution network rationalisation and be a suitable analytical tool to facilitate continuous improvement.

Findings

Based on the DEA results, it is concluded that overall distribution efficiency of the part of the retail network under study can be improved by either closing the less efficient stores or merging them with the others in the same service areas to streamline the network. Such rationalisation will help aggregate demand and improve vehicle utilisation for distribution with minor impact on current level of customer service.

Research limitations/implications

This study lends insight into the use of DEA, together with other analyses, for distribution network rationalisation. This approach is less data hungry and relatively easy to implement than full‐fledged optimisation through integer programming. To serve mainly as a proof of concept and an illustration of the approach, the scope of the study is limited to six stores in the retail network with relative performance in distribution evaluated on a single input and a single output variables.

Practical implications

Managers can use DEA to benchmark the distribution performance of their stores against the best performers in the retail network so as to identify areas for improvement. The approach can also assist in the adoption of best practice and facilitate more effective allocation of resources across the entire retail network.

Social implications

Retail network rationalisation through benchmarking with DEA can facilitate continuous improvement in distribution efficiency. This will help reduce fuel consumption, carbon emission, as well as other pollutions such as noise and traffic congestion.

Originality/value

Research in retail network performance using DEA to date is mainly on comparative performance of supermarkets within or between chains. The focus is mainly placed on the relationship between floor area, workforce, and sales. This paper fills the gap in the literature by applying DEA in distribution network rationalisation instead of mere performance comparison of individual stores. It focuses on distribution costs rather than store attributes and supplements DEA with other techniques to obtain a fuller picture of the overall network efficiency in terms of distribution. It also contributes to a better understanding of how demand management can affect distribution efficiency of the retail network.
Exploring current benchmarking practices in the Egyptian hotel sector
Authors: Nassar Mohamed
Published: October 2012

Purpose

The purpose of this paper is to investigate the current state, understanding and opinions of benchmarking in the Egyptian hotel sector in order to establish its perceived benefits, obstacles, and possible improvements.

Design/methodology/approach

By way of a three part structured self‐administrated questionnaire, a representative sample of 128 two, three, four and five star hotels (giving a response rate of 29 percent) in Sharm El‐Sheikh, Cairo, Alexandria and Luxor were examined. Descriptive statistics were drawn from general hotel data, in addition to data pertaining to the understanding of benchmarking and the impressions or experiences of its barriers and future use.

Findings

A generally positive attitude towards benchmarking predominated, with the majority of participants understanding benchmarking to be a quality enhancement tool that can bring about better service. Most perceived it to be a useful and inexpensive strategy to connect to other businesses. Furthermore, senior management staff were seen to play a crucial role in quality improvement. However, barriers to its wider or continuing use exist, with 25 percent of participants unwilling or unsure to consider its usage in the future. Limitations of benchmarking included too much data collection and the unwillingness of potential benchmarking partners in sharing data.

Research limitations/implications

Identifying specific obstacles to effective benchmarking must be undertaken so that they may be practically overcome. In addition conducting multiple case studies to compare benchmarking practices around the Arab world, or in conjunction with the US and UK, would be of great value to the industry.

Originality/value

There is an absence of empirical research into benchmarking applications in the hospitality industry, especially in North Africa and the Middle East. The present study addresses the lack of data regarding benchmarking within the context of the Egyptian hotel sector.
Lean Six Sigma for higher education institutions (HEIs)
Authors: Antony Jiju , Krishan Netasha , Cullen Donna , Kumar Maneesh
Published: October 2012

Purpose

The purpose of this paper is to critically evaluate whether Lean Six Sigma (LSS) can be a powerful business improvement methodology for improving the efficiency and effectiveness of higher education institutions (HEIs). The paper will also explore the fundamental challenges, barriers and critical success factors for the introduction and development of LSS in the HE context. The last part of the paper is to understand the role of tools and techniques for the sustainability of this initiative for making the HEIs more efficient and effective.

Design/methodology/approach

The paper discusses whether LSS can be a useful and systematic approach to tackle operational and strategic issues within the HE industry. The authors use secondary data from literature to justify the need for this powerful approach and the benefits of adopting this business process improvement strategy within the HEIs.

Findings

The paper presents the challenges and barriers to be encountered during the introduction of LSS in the higher education sector, most useful tools and techniques for process improvement problems, success factors which are essential for the implementation and sustainability of LSS.

Research limitations/implications

This is a very theoretical paper based on the existing literature and authors’ experiences in the HE sector. The next stage of the research is to carry out empirical studies in a number of HEIs and develop a practical and useful roadmap for the implementation and sustainability of LSS as a business process improvement methodology.

Originality/value

This paper makes an attempt to remove the myth that LSS is confined to manufacturing. It also demonstrates, through relevant existing literature and authors’ experiences, that LSS is equally applicable to public sector organisations and in particular HEIs. Although lean has been adopted by a few HEIs in the UK and abroad, very few HEIs have adopted the integrated LSS approach for waste reduction and variability reduction, which leads to superior performance and enhanced student satisfaction.
A simulation study of a new rate‐and‐queue‐based active queue management algorithm
Authors: Asghar Jomah Adham Ali , Mat Tahar Razman
Published: October 2012

Purpose

Nowadays, e‐queues are built up everywhere where customer online service is necessary such as in banks' e‐service, enterprises' e‐business, etc. In order to enhance quality of service (QoS), active queue management (AQM) algorithms are frequently employed due to their efficiency in congestion avoidance as well as the differentiated forwarding of packets. This paper aims at developing a novel AQM algorithm to better QoS in terms of congestion prediction, queuing delay, packet loss and link utility, etc.

Design/methodology/approach

Upon the traditional designs of AQM, this paper establishes a new integrated AQM scheme (RQ‐AQM) by employing input rate and current queue length to calculate the packet dropping/marking probability. In this way, the rate feedback control enables to rapid response to congestion, decreasing the packet loss from buffer overflow. Meanwhile, the queue length feedback control stabilizes the queue length around a given target, achieving predictable queuing delay and lower delay jitter. Thus, the main feature of the design is to use coefficients of both proportional rate control and proportional‐integral queue length control, and to simplify parameter setting, the control parameters were scaled by the link capacity C to normalize the rate and by the bandwidth‐delay product BDP to normalize the queue length, respectively.

Findings

The stability performance of RQ‐AQM was tested via simulation under several conditions. The results proved that it is able to maintain the queue length around the given target. Also, the comparison results with other AQM schemes, including RED, ARED, PI controller, AVQ and REM, demonstrated the superiority of RQ‐AQM in low packet loss, faster convergence to target queue length and closest to the target queue length.

Research limitations/implications

The main limitation of this study is that all the simulations were merely under a single bottleneck network topology. Furthermore, the system stability was examined under just a few cases. Other cases like TCP connections mixed with HTTP connections, or UDP flows, etc. can also be tested. Furthermore, the multiple bottleneck scenarios should be covered in the future work with more parameters set to enhance the proved results.

Practical implications

The paper sets clear but ideal conditions for the performance of proposed algorithm; so the simulation results can only be used as a rough reference instead of an exact practical one. But the concepts the paper attempted to advocate could be considered seriously.

Social implications

The scope of the paper is within the general theory of AQM. So it can be referred to any specific field that employs AQM technology, no matter locally or globally.

Originality/value

There are not much new brand contents in the paper. The main contribution is on some extension of the known related work.
The definition system and computational rule of grey determinant and its application to n grey equations with n grey linear equations
Authors: Li Qiao‐Xing , Wang Nai‐Ang , Chen Shi‐Cheng
Published: October 2012

Purpose

This paper attempts to establish the conceptional and computational systems of grey determinant and apply it to solve n grey equations with n grey linear equations, which can be viewed as the important parts of grey mathematics.

Design/methodology/approach

Starting from the fact that missing information often appears in complex systems, the true values of elements when constructing a determinant and of coefficients when solving n equations with n linear equations cannot be obtained, so they are uncertain. However, their ranges can be obtained by using correct investigation methods. The uncertain elements and coefficients are grey and their ranges are number‐covered sets. On the basis of the results of Li and Wang, the paper systematically proposes the definition system of grey determinant and n grey linear equations, and utilizes the computational rules of grey determinant to solve the n grey equations with n grey linear equations. Some numerical examples are computed to illustrate the results in this paper.

Findings

The results show that the ranges of grey value of grey determinant and grey solutions of grey equations with n grey linear equations can be obtained by using computational rules proposed.

Practical implications

Because the determinant and the linear equations have been widely used in many fields such as system controlling, economic analysis and social management, and the missing information is a general phenomenon for complex systems, grey determinant and grey linear equations may have great potential application in the real world. The method realizes the feasibility of system analysis under uncertain situations.

Originality/value

The paper succeeds in providing systematic results of computation of uncertain determinant and n linear equations by using grey systems theory and enriches the contents of grey mathematics.
Equipment maintainability and its influencing factors analysis based on grey system theory
Authors: Ke Hong‐fa , Du Hong‐Mei , He Ke , Yu Xiao‐Hong
Published: October 2012

Purpose

The purpose of this paper is to solve the comprehensive evaluation of the equipment maintainability level based on grey system theory, and make an analysis of the corresponding influencing factors and their prioritization process.

Design/methodology/approach

Considering the diversity, uncertainty and small sample size of the influencing factors of the equipment maintainability level, a multilayer evaluation attribute system is set up, and the grey relational method is utilized to assess the equipment's comprehensive maintainability. First, the bottom layer relational coefficient and weighted relational degree are analyzed, and, by means of the focus of relational degree through the bottom layer to top layer, the general evaluation of the equipment maintainability is carried out. Second, the equipment maintainability level and its influencing factors model, i.e. GM(1,N) model are set up, and the prioritization of the influencing factors is achieved through the comparison of the size of the model drive coefficients. Finally, the practical example calculation results show that this method has not only realized a sensible and effective evaluation of the equipment maintainability level, but also provided a prioritization of the influencing factors, which helps to focus attention on the major influencing factors and make this method of significant engineering application value in the improvement of the equipment maintainability level.

Findings

The modeling of electronic equipment maintainability level and analysis of its corresponding practical example prove that grey system theory could not only perform a comprehensive evaluation of the equipment maintainability level, but also provide a quantitative analysis of its various influencing factors, whereas, other methods such as fuzzy mathematics, etc. can only make a general evaluation of the equipment maintainability level.

Practical implications

This paper has realized an integral evaluation of the equipment maintainability level and has made an analysis of the prioritization of its various influencing factors. These investigation results could be introduced as a promising innovative idea in the evaluation of the equipments' other performances and the prioritization of its various corresponding influencing factors.

Originality/value

Considering the diversity and uncertainty of influencing factors of the equipment maintainability level, this paper has realized a multilayer evaluation attribute system to perform a comprehensive evaluation of equipment maintainability level by means of weighted grey relational degree model. Furthermore, the prioritization of its various influencing factors is achieved based on the GM(1,N) model.
Eosinophilic pustular folliculitis: A review of the Japanese published works
Authors: Katoh Mayumi , Nomura Takashi , Miyachi Yoshiki , Kabashima Kenji
Published: October 2012

Eosinophilic pustular folliculitis (EPF), also known as Ofuji's disease, is an inflammatory dermatosis that was first described in Japan in 1970. More than 300 cases have been reported so far, and 113 Japanese cases have been reported in Japan since 1980. To comprehend the characteristics of Japanese EPF cases, we classified these cases into three types: classic, immunosuppression‐associated (IS‐EPF), and infancy‐associated (I‐EPF). Trends in age of onset and in distribution and characterization of eruptions differed between the types. We found 91 cases of classic EPF (mean age, 39.7 years), consisting of 66 males (73%) and 25 females (27%), in most of which eruptions primarily affected the face; 18 cases of IS‐EPF (44.2 years), consisting of 15 males (83%) and three females (17%), in which eruptions affected the face less predominantly; and four cases of I‐EPF (7.0 years), consisting of two males (50%) and two females (50%), primarily affecting the scalp. The number of IS‐EPF cases has increased since the late 1990s, reflecting the increasing number of HIV‐positive patients in Japan. Systemic non‐steroidal anti‐inflammatory drugs were effective in more than 70% of cases. Dimethyl diphenyl sulfone, antibiotics including minocycline, psoralen plus ultraviolet A therapy and ultraviolet B treatments worked in some cases. Topical steroids and tacrolimus were also effective in some cases of EPF, while topical indomethacin was less effective.
Physician Styles of Patient Management as a Potential Source of Disparities: Cluster Analysis from a Factorial Experiment
Authors: Lutfey Karen E. , Gerstenberger Eric , McKinlay John B.
Published: October 2012

Objective

To identify styles of physician decision making (as opposed to singular clinical actions) and to analyze their association with variations in the management of a vignette presentation of coronary heart disease (CHD).

Data Source

Primary data were collected from primary care physicians in North and South Carolina.

Study Design

In a balanced factorial experimental design, primary care physicians viewed one of 16 (24) video vignette presentations of CHD and provided detailed information about how they would manage the case.

Data Collection Method

256 MD primary care physicians were interviewed face‐to‐face in North and South Carolina.

Principal Findings

We identify three clusters depicting unique styles of CHD management that are robust to controls for physician (gender and level of experience) and patient characteristics (age, gender, socioeconomic status, and race) as well as key organizational features of physicians' work settings. Physicians in Cluster 1 “Cardiac” (N = 92) were more likely to focus on cardiac issues compared with their counterparts; physicians in Cluster 2 “Talkers” (N = 93) were more likely to give advice and take additional medical history; whereas physicians in Cluster 3 “Minimalists” (N = 71) were less likely than their counterparts to take action on any of the types of management behavior.

Conclusions

Variations in styles of decision making, which encompass multiple outcome variables and extend beyond individual‐level demographic predictors, may add to our understanding of disparities in health quality and outcomes.