bluuebunny/crossref_metadata_2025_split huggingface dataset:
Gene set analysis: limitations in popular existing methods and proposed improvements
Authors: Mishra Pashupati , Törönen Petri , Leino Yrjö , Holm Liisa 
Published: June 2014

AbstractMotivation: Gene set analysis is the analysis of a set of genes that collectively contribute to a biological process. Most popular gene set analysis methods are based on empirical P -value that requires large number of permutations. Despite numerous gene set analysis methods developed in the past decade, the most popular methods still suffer from serious limitations.Results: We present a gene set analysis method (mGSZ) based on Gene Set Z-scoring function (GSZ) and asymptotic P -values. Asymptotic P -value calculation requires fewer permutations, and thus speeds up the gene set analysis process. We compare the GSZ-scoring function with seven popular gene set scoring functions and show that GSZ stands out as the best scoring function. In addition, we show improved performance of the GSA method when the max-mean statistics is replaced by the GSZ scoring function. We demonstrate the importance of both gene and sample permutations by showing the consequences in the absence of one or the other. A comparison of asymptotic and empirical methods of P -value estimation demonstrates a clear advantage of asymptotic P -value over empirical P -value. We show that mGSZ outperforms the state-of-the-art methods based on two different evaluations. We compared mGSZ results with permutation and rotation tests and show that rotation does not improve our asymptotic P -values. We also propose well-known asymptotic distribution models for three of the compared methods.Availability and implementation : mGSZ is available as R package from cran.r-project.org.Contact: pashupati.mishra@helsinki.fiSupplementary information: Available at http://ekhidna.biocenter.helsinki.fi/downloads/pashupati/mGSZ.html
Do high-redshift quasars have powerful jets?
Authors: Fabian A. C. , Walker S. A. , Celotti A. , Ghisellini G. , Mocz P. , Blundell K. M. , McMahon R. G. 
Published: June 2014

Abstract
Double-lobed radio galaxies a few hundreds of kpc in extent, like Cygnus A, are common at redshifts of 1–2, arising from some 10 per cent of the most powerful active galactic nuclei (AGN). At higher redshifts, they are rare, with none larger than a few tens of kpc known above redshift z ∼ 4. Recent studies of the redshift evolution of powerful jetted objects indicate that they may constitute a larger fraction of the AGN population above redshift 2 than that appears from a simple consideration of detected GHz radio sources. The radio band is misleading as the dramatic (1 + z)4 boost in the energy density of the cosmic microwave background (CMB) causes inverse Compton scattering to dominate the energy losses of relativistic electrons in the extended lobes produced by jets, making them strong X-ray, rather than radio, sources. Here, we investigate limits to X-ray lobes around two distant quasars, ULAS J112001.48+064124.3 at z = 7.1 and SDSS J1030+0524 at z = 6.3, and find that powerful jets could be operating yet be currently undetectable. Jets may be instrumental in the rapid build-up of billion M⊙ black hole at a rate that violates the Eddington limit.
Decreased Functional Connectivity and Disturbed Directionality of Information Flow in the Electroencephalography of Intensive Care Unit Patients with Delirium after Cardiac Surgery
Authors: van Dellen Edwin , van der Kooi Arendina W. , Numan Tianne , Koek Huiberdina L. , Klijn Francina A. M. , Buijsrogge Marc P. , Stam Cornelis J. , Slooter Arjen J. C. 
Published: June 2014

Abstract

Background:
In this article, the authors explore functional connectivity and network topology in electroencephalography recordings of patients with delirium after cardiac surgery, aiming to improve the understanding of the pathophysiology and phenomenology of delirium. The authors hypothesize that disturbances in attention and consciousness in delirium may be related to alterations in functional neural interactions.

Methods:
Electroencephalography recordings were obtained in postcardiac surgery patients with delirium (N = 25) and without delirium (N = 24). The authors analyzed unbiased functional connectivity of electroencephalography time series using the phase lag index, directed phase lag index, and functional brain network topology using graph analysis.

Results:
The mean phase lag index was lower in the α band (8 to 13 Hz) in patients with delirium (median, 0.120; interquartile range, 0.113 to 0.138) than in patients without delirium (median, 0.140; interquartile range, 0.129 to 0.168; P < 0.01). Network topology in delirium patients was characterized by lower normalized weighted shortest path lengths in the α band (t = −2.65; P = 0.01). δ Band–directed phase lag index was lower in anterior regions and higher in central regions in delirium patients than in nondelirium patients (F = 4.53; P = 0.04, and F = 7.65; P < 0.01, respectively).

Conclusions:
Loss of α band functional connectivity, decreased path length, and increased δ band connectivity directed to frontal regions characterize the electroencephalography during delirium after cardiac surgery. These findings may explain why information processing is disturbed in delirium.
Do Lordotic Cages Provide Better Segmental Lordosis Versus Nonlordotic Cages in Lateral Lumbar Interbody Fusion (LLIF)?
Authors: Sembrano Jonathan N. , Horazdovsky Ryan D. , Sharma Amit K. , Yson Sharon C. , Santos Edward R.G. , Polly David W. 
Published: June 2014

Study Design:
A retrospective comparative radiographic review.

Objective:
To evaluate the radiographic changes brought about by lordotic and nonlordotic cages on segmental and regional lumbar sagittal alignment and disk height in lateral lumbar interbody fusion (LLIF).

Summary of Background Data:
The effects of cage design on operative level segmental lordosis in posterior interbody fusion procedures have been reported. However, there are no studies comparing the effect of sagittal implant geometry in LLIF.

Methods:
This is a comparative radiographic analysis of consecutive LLIF procedures performed with use of lordotic and nonlordotic interbody cages. Forty patients (61 levels) underwent LLIF. Average age was 57 years (range, 30–83 y). Ten-degree lordotic PEEK cages were used at 31 lumbar interbody levels, and nonlordotic cages were used at 30 levels. The following parameters were measured on preoperative and postoperative radiographs: segmental lordosis; anterior and posterior disk heights at operative level; segmental lordosis at supra-level and subjacent level; and overall lumbar (L1–S1) lordosis. Measurement changes for each cage group were compared using paired t test analysis.

Results:
The use of lordotic cages in LLIF resulted in a significant increase in lordosis at operative levels (2.8 degrees; P=0.01), whereas nonlordotic cages did not (0.6 degrees; P=0.71) when compared with preoperative segmental lordosis. Anterior and posterior disk heights were significantly increased in both groups (P<0.01). Neither cage group showed significant change in overall lumbar lordosis (lordotic P=0.86 vs. nonlordotic P=0.25).

Conclusions:
Lordotic cages provided significant increase in operative level segmental lordosis compared with nonlordotic cages although overall lumbar lordosis remained unchanged. Anterior and posterior disk heights were significantly increased by both cages, providing basis for indirect spinal decompression.
French consumer perception, preference of, and willingness to pay for fresh fruit based on country of origin
Authors: Gao Zhifeng , Sing Wong Shu , A. House Lisa , H. Spreen Thomas 
Published: June 2014

Purpose
– The purpose of this study is to determine French consumer perceptions and preferences for fresh fruit from different countries. French consumer willingness to pay (WTP) for citrus fruit and the factors affecting WTP are also determined.

Design/methodology/approach
– An online consumer survey was conducted in France to collect data on consumer perceptions and preferences for fresh fruits from different countries. The contingent valuation method is used to estimate consumer WTP for fresh citrus fruit. A double hurdle model is used to determine the factors that have substantial impact on consumer preferences.

Findings
– Results show that fresh fruit from China was perceived as the lowest quality, the least safe, and the cheapest among the fruit from various countries. French consumers had the highest stated WTP for fresh fruit from France, followed by fruit from Spain. In addition, consumer WTP for country of origin varies by type of fruit.

Research limitations/implications
– The contingent valuation method does not require consumers to purchase the product being evaluated, which may overestimate consumer stated WTP.

Practical implications
– More domestically produced fresh fruit may be provided to satisfy consumer demand for fruit produced in their own countries. As second in consumer stated WTP, Spain should take advantage of the lower price high quality perceptions of their fresh fruit to gain a larger market share in France. Lower rated countries, such as China, Brazil, and Israel, need to improve consumer perception of the fruit from their countries to gain a better position in the fresh fruit market of France.

Originality/value
– This is the first paper to present French consumer perception of fresh fruit and WTP for citrus fruit from different countries.
Hard economic times: a dream for discounters
Authors: Lamey Lien 
Published: June 2014

Purpose– The aim of this paper is to study the relationship between the popularity of discount stores and the aggregate business cycle: Does discounters' market share go up during economic contractions and go down during economic expansions? Does the aggregate business cycle contribute to the long-term growth of discounters' success? Does the relationship between discounters and the economy differ across discounter types, namely hard versus soft discounters?Design/methodology/approach– The study will consider the relationship between discounters' market share and the aggregate economy between 1991 and 2008 for 15 Western European countries. Moreover, aggregated data is provided for the Western European region as a whole, which distinguishes hard from soft discounters' share. Recent time-series techniques are used to disentangle the temporary versus permanent effects of economic contractions on discounters' share.Findings– The aggregate business cycle induces temporary upward and downward swings in discounters' market share. Moreover, part of the increase in discounters' share during an economic contraction remains beyond the contraction, resulting in a permanent boost in discounters' popularity. Same substantive findings are found for each discount type (i.e. hard and soft).Practical implications– In economic contraction years the growth rate of both hard and soft discounters accelerates, leaving permanent scars on the performance levels of traditional retailers. Discounters should try to further enhance their increased popularity when the economy turns sour. Traditional retailers, on the other hand, should try to prevent consumers from switching to discounters during contractions. Future research should explore the strategies that are called for in order to do this.Originality/value– Discounters are the fastest growing grocery format in Europe. Traditional retailers can no longer afford to ignore them. As such, a better understanding of the drivers of this growth is called for. This study highlights one of the potential drivers, namely the economic climate, a driver that is widely discussed in the business press with substantial implications for grocery channel management.
Dynamics of price premiums in loyalty programs
Authors: Sayman Serdar , J. Hoch Stephen 
Published: June 2014

Purpose
– A loyalty program might influence buyer behavior in several ways. Prior research offers evidence that buyers might increase the frequency of purchases and volume per occasion in a loyalty program; however, the effect on buyers' price tolerance has not been studied before. The aim of this paper is to examine buyers' willingness to pay a price premium for a firm offering a loyalty program reward.

Design/methodology/approach
– An analytical model of dynamic consumer choice is developed, where one of the two selling firms offers a reward for a certain number of purchases. The maximum price premium that a normatively rational buyer should be willing to pay at each level of accumulated purchases is obtained. A price tolerance in controlled settings is obtained and these are compared with normative solutions.

Findings
– Analytically, it is shown that the maximum price premium increases as purchases are accumulated; and the exact solutions can be found, given the price distributions and program design parameters. In the empirical studies it is found that individuals' maximum premiums are less than the normative levels. On the other hand, as buyers accumulate purchases from the reward offering firm, and get closer to the reward, maximum premiums paid increase – particularly when the reward is immediate.

Originality/value
– This paper contributes to the loyalty programs literature by examining the price premium, or switching barrier, aspect of buyer response. Furthermore, the paper not only models and solves the normative strategy, but also obtains actual price tolerance in laboratory settings.
Shopping at different food retail formats
Authors: Hino Hayiel 
Published: June 2014

Purpose
– The aim of this paper is to address intertype cross-shopping behavior – that is, the behavior that characterizes consumers who divide their grocery shopping between two or more different food formats. In particular, the study attempts to shed light on the cross-shopping phenomenon by employing a new research approach that examines format-selective use. Thus, the study examines how various factors, especially way of life aspects typically associated with food consumption, drive consumers to cross-shop between different food formats.

Design/methodology/approach
– The study employs data collected from two surveys involving 637 Israeli Jewish and Arab consumers. The conceptual framework and hypothesis are tested using multiple regression analyses.

Findings
– The empirical results support our claim that the research approach applied in this study better explains the cross-shopping phenomenon. Specifically, the analysis provides strong support for the effect of consumers' way of life on cross-shopping behavior.

Practical implications
– The paper provides managerial and planning implications to modern retailers and managers of international retail firms that operate in or plan to enter non-Western markets.

Originality/value
– This paper contributes to the available literature in several ways. In particular, the paper suggests a systematic and comprehensive conceptual framework that identifies the key determinants of cross-shopping decisions and the relations between these and supermarkets' market share growth.
Measuring and exploring factors affecting students’ willingness to engage in peer mentoring
Authors: Noufou Ouedraogo , Rezania Davar , Hossain Muhammad 
Published: June 2014

Purpose– The purpose of this paper is to measure students’ willingness to mentor their peers and explores key factors to student peer mentoring effectiveness.Design/methodology/approach– The paper uses a hybrid research methodology consisting of a survey and a focus group discussion. The survey was conducted with students of a bachelor of commerce (BCom) program of a North American university to analyze the impact of organizational culture and altruism on their willingness to mentor their peers. The focus group discussion was carried out with students of the same program to explore the objectives, focus, and factors contributing to their willingness to mentor and to peer mentoring effectiveness.Findings– Organizational culture and altruism significantly affect students’ emotional and intentional willingness to mentor their peers. Peer mentoring can help students prepare their transition from high school to university, guide them through university programs, and help them prepare their transition from university to workplace. Critical factors to peer mentoring effectiveness include a good fit between mentors and mentees, a reasonable ratio of mentor to protégés, and an understanding of and a willingness to address each student's specific needs.Practical implications– Business schools should embrace and promote a culture of mutual help, look for altruistic students as prospective peer mentors, and promote voluntary student peer mentoring. A mentoring program should be flexible enough to meet each student's needs. Attention should be paid to finding a good fit between mentors and protégés. Communication should focus on the benefits of student peer mentoring for mentors and protégés.Originality/value– This research brings empirical evidence on peer mentoring by testing and confirming the impact of altruism and organizational culture on students’ willingness to mentor their peers. It also provides practical insight to business schools for implementing student peer mentoring programs.
To which extent do projects explore the opportunity space?
Authors: Samset Knut , Andersen Bjorn , Austeng Kjell 
Published: June 2014

Purpose
– The purpose of this paper is to explore a selection of projects to understand how conceptual appraisals and choice of concepts are handled, and to which extent the conceptual opportunity space is exploited.

Design/methodology/approach
– The study is essentially case based, and rooted in a number of in-depth studies of single-project cases. Its study combines information from document studies with interview data, and culminates in normative recommendations.

Findings
– The study found that the projects do indeed not exploit the opportunity space to a very large extent. The lessons from the present study is that the final choice is determined more by decision makers than the analysts, and will often be the result of policy and preferences more than objective reasoning. Which again suggests that the efforts as analysts will often be in vain.

Research limitations/implications
– These findings could influence theoretical models outlining project establishment and decision processes.

Practical implications
– The study has identified many shortcomings in public sector processes that could be utilized to alter such processes.

Originality/value
– The study is original in that it focusses on the concept development phase of projects, rather than the traditional execution phase, and has studied decision processes.
Probabilistic composition in quality management in the retail trade sector
Authors: Parracho Sant’Anna Annibal , Angulo Meza Lidia , Otavio Araujo Ribeiro Rodrigo 
Published: June 2014

Purpose
– The purpose of this paper is to discuss the application of a method for combining multiple criteria based on the transformation of numerical evaluations into probabilities of preference. It is applied to compare failure risks and to measure efficiency in the retail trade sector.

Design/methodology/approach
– The main conceptual aspect of the method employed is taking into account uncertainty. Its other important feature is allowing for the combination of evaluations in terms of joint probabilities. This avoids the need of assigning weights to the criteria. In the context of failure modes and effects analysis (FMEA) it provides a probabilistic derivation for priority scores. An application of FMEA to the sector of services is discussed. Another area of application investigated is the assessment of efficiency.

Findings
– Details of the application of the probabilistic composition in the evaluation of modes of failure and in the comparison of operational efficiencies of retail stores are evidenced.

Research limitations/implications
– The study is limited to the retail market. Other factors might be considered in the reliability analysis and other inputs and outputs might be added to the productivity evaluation. The extension of the study to other cases and sectors is straightforward.

Practical implications
– Features of the evaluation of modes of failure and of productivity in the retail sector are revealed.

Originality/value
– The main contribution of this paper is showing how to use a probabilistic framework to measure efficiency in services management.
The effect of aggregating multivariate performance parameters in a quality award process
Authors: Beshah Birhanu 
Published: June 2014

Purpose
– Quality awards, commonly, have basic criteria and sub-criteria to evaluate applicants based on the quality management principles and philosophies. The purpose of this paper is to examine the method of selecting award winners and its consequences.

Design/methodology/approach
– Award winners’ and non-award winners’ performances of the Ethiopian Quality Award are the study groups. The criteria and sub-criteria evaluation results of the award were collected and analysed by the Mahalanobis-Taguchi System.

Findings
– The research assumed that award winners’ performances are exceptionally outstanding. However, the result does not justify the assumption. Hence, the drawback of aggregating multivariate performance measures in a quality award is proven. Mahalanobis distance is proposed as alternative approach to evaluate and select organizations.

Practical implications
– The outcome of this research will help award givers, evaluators and participants to understand the real difficulty to select very few organizations among applicants. Furthermore, it helps to consider the possible error when aggregating individual performance.

Originality/value
– Aggregating performances is a common practice in quality awards evaluation process but this paper proved its drawback.
Experimental investigations on the effect of heat-treatment parameters on the wear behavior of aluminum hybrid composites
Authors: Velmurugan C. , Subramanian R. , Ramakrishnan S.S. , Thirugnanam S. , Kannan T. , Anandavel B. 
Published: June 2014

Purpose
– The purpose of this paper is to investigate the influence of most predominant heat-treatment parameters on the wear behavior of Al6061 hybrid composite reinforced with 10 weight per cent SiC and 2 weight per cent graphite particles.

Design/methodology/approach
– The aluminum hybrid composite was produced using stir casting process. Wear testing of heat-treated samples was carried out using a pin-on-disc apparatus. Experiments were conducted by applying design of experiments (DOE) technique. The experimental values were used for formulation of a mathematical model. The wear surfaces of composite specimens were analyzed using scanning electron microscope (SEM).

Findings
– The volume loss of heat-treated composite initially decreased with increasing aging duration. This was followed by the attainment of a minimum and then a reversal in the trend at longer aging times. SEM micrographs of the wear surfaces of the composite show that the wear mechanisms were abrasion, delamination and adhesion.

Originality/value
– In this paper, the hybrid composite was produced using stir casting route, and its wear properties after heat treatment were tested using pin-on-disc apparatus. It was found that heat treatment had a profound effect on the wear behaviour of the developed composite.