bluuebunny/crossref_metadata_2025 huggingface dataset:
Inhibitory stroke neighbour priming in character recognition and reading in Chinese
Authors: Wang Jingxin , Tian Jing , Han Weijin , Liversedge Simon P. , Paterson Kevin B.
Published: April 2014

In alphabetic languages, prior exposure to a target word's orthographic neighbour influences word recognition in masked priming experiments and the process of word identification that occurs during normal reading. We investigated whether similar neighbour priming effects are observed in Chinese in 4 masked priming experiments (employing a forward mask and 33-ms, 50-ms, and 67-ms prime durations) and in an experiment that measured eye movements while reading. In these experiments, the stroke neighbour of a Chinese character was defined as any character that differed by the addition, deletion, or substitution of one or two strokes. Prime characters were either stroke neighbours or stroke non-neighbours of the target character, and each prime character had either a higher or a lower frequency of occurrence in the language than its corresponding target character. Frequency effects were observed in all experiments, demonstrating that the manipulation of character frequency was successful. In addition, a robust inhibitory priming effect was observed in response times for target characters in the masked priming experiments and in eye fixation durations for target characters in the reading experiment. This stroke neighbour priming was not modulated by the relative frequency of the prime and target characters. The present findings therefore provide a novel demonstration that inhibitory neighbour priming shown previously for alphabetic languages is also observed for nonalphabetic languages, and that neighbour priming (based on stroke overlap) occurs at the level of the character in Chinese.
PKA-dependent dynein switching from lysosomes to adenovirus: A novel form of host–virus competition
Authors: Scherer Julian , Yi Julie , Vallee Richard B.
Published: April 2014

Cytoplasmic dynein is responsible for transport of several viruses to the nucleus. Adenovirus recruits dynein directly. Transport depends on virus-induced activation of protein kinase A (PKA) and other cellular protein kinases, whose roles in infection are poorly understood. We find that PKA phosphorylates cytoplasmic dynein at a novel site in light intermediate chain 1 (LIC1) that is essential for dynein binding to the hexon capsid subunit and for virus motility. Surprisingly, the same LIC1 modification induces a slow, but specific, dispersal of lysosomes (lyso)/late endosomes (LEs) that is mediated by inhibition of a newly identified LIC1 interaction with the RILP (Rab7-interacting lysosomal protein). These results identify an organelle-specific dynein regulatory modification that adenovirus uses for its own transport. PKA-mediated LIC1 phosphorylation causes only partial lyso/LE dispersal, suggesting a role for additional, parallel mechanisms for dynein recruitment to lyso/LEs. This arrangement provides a novel means to fine tune transport of these organelles in response to infection as well as to developmental and physiological cues.
Talin-bound NPLY motif recruits integrin-signaling adapters to regulate cell spreading and mechanosensing
Authors: Pinon Perrine , Pärssinen Jenita , Vazquez Patricia , Bachmann Michael , Rahikainen Rolle , Jacquier Marie-Claude , Azizi Latifeh , Määttä Juha A. , Bastmeyer Martin , Hytönen Vesa P. , Wehrle-Haller Bernhard
Published: April 2014

Integrin-dependent cell adhesion and spreading are critical for morphogenesis, tissue regeneration, and immune defense but also tumor growth. However, the mechanisms that induce integrin-mediated cell spreading and provide mechanosensing on different extracellular matrix conditions are not fully understood. By expressing β3-GFP-integrins with enhanced talin-binding affinity, we experimentally uncoupled integrin activation, clustering, and substrate binding from its function in cell spreading. Mutational analysis revealed Tyr747, located in the first cytoplasmic NPLY747 motif, to induce spreading and paxillin adapter recruitment to substrate- and talin-bound integrins. In addition, integrin-mediated spreading, but not focal adhesion localization, was affected by mutating adjacent sequence motifs known to be involved in kindlin binding. On soft, spreading-repellent fibronectin substrates, high-affinity talin-binding integrins formed adhesions, but normal spreading was only possible with integrins competent to recruit the signaling adapter protein paxillin. This proposes that integrin-dependent cell–matrix adhesion and cell spreading are independently controlled, offering new therapeutic strategies to modify cell behavior in normal and pathological conditions.
Alex Mogilner: Math illuminates biology
Authors: Sedwick Caitlin
Published: April 2014

Mogilner uses modeling to probe and explain the behavior of cells and their cytoskeleton.
Local control of TRPV4 channels by AKAP150-targeted PKC in arterial smooth muscle
Authors: Mercado Jose , Baylie Rachael , Navedo Manuel F. , Yuan Can , Scott John D. , Nelson Mark T. , Brayden Joseph E. , Santana Luis F.
Published: April 2014

Transient receptor potential vanilloid 4 (TRPV4) channels are Ca2+-permeable, nonselective cation channels expressed in multiple tissues, including smooth muscle. Although TRPV4 channels play a key role in regulating vascular tone, the mechanisms controlling Ca2+ influx through these channels in arterial myocytes are poorly understood. Here, we tested the hypothesis that in arterial myocytes the anchoring protein AKAP150 and protein kinase C (PKC) play a critical role in the regulation of TRPV4 channels during angiotensin II (AngII) signaling. Super-resolution imaging revealed that TRPV4 channels are gathered into puncta of variable sizes along the sarcolemma of arterial myocytes. Recordings of Ca2+ entry via single TRPV4 channels (“TRPV4 sparklets”) suggested that basal TRPV4 sparklet activity was low. However, Ca2+ entry during elementary TRPV4 sparklets was ∼100-fold greater than that during L-type CaV1.2 channel sparklets. Application of the TRPV4 channel agonist GSK1016790A or the vasoconstrictor AngII increased the activity of TRPV4 sparklets in specific regions of the cells. PKC and AKAP150 were required for AngII-induced increases in TRPV4 sparklet activity. AKAP150 and TRPV4 channel interactions were dynamic; activation of AngII signaling increased the proximity of AKAP150 and TRPV4 puncta in arterial myocytes. Furthermore, local stimulation of diacylglycerol and PKC signaling by laser activation of a light-sensitive Gq-coupled receptor (opto-α1AR) resulted in TRPV4-mediated Ca2+ influx. We propose that AKAP150, PKC, and TRPV4 channels form dynamic subcellular signaling domains that control Ca2+ influx into arterial myocytes.
Asymptotic geometry of Banach spaces and uniform quotient maps
Authors: Dilworth S. , Kutzarova Denka , Lancien G. , Randrianarivony N.
Published: April 2014

Recently, Lima and Randrianarivony pointed out the role of the property

(
β
)

(\beta )

of Rolewicz in nonlinear quotient problems and answered a ten-year-old question of Bates, Johnson, Lindenstrauss, Preiss and Schechtman. In the present paper, we prove that the modulus of asymptotic uniform smoothness of the range space of a uniform quotient map can be compared with the modulus of

(
β
)

(\beta )

of the domain space. We also provide conditions under which this comparison can be improved.
A beta family in the homotopy of spheres
Authors: Shimomura Katsumi
Published: April 2014

Let

p
p

be a prime number greater than three. In the

p
p

-component of stable homotopy groups of spheres, Oka constructed a beta family from a

v
2

v_2

-periodic map on a four cell complex. In this paper, we construct another beta family in the groups at a prime

p
p

greater than five from a

v
2

v_2

-periodic map on an eight cell complex.
The Elements: A Very Short Introduction
Authors: Ball Philip
Published: April 2014

The Elements: A Very Short Introduction traces the history and cultural impact of the elements on humankind, and examines why people have long sought to identify the substances around them. Looking beyond the Periodic Table, our relationship with matter is examined, from the uncomplicated vision of the Greek philosophers who believed there were four elements — earth, air, fire, and water — to the work of modern–day scientists in creating elements such as hassium and meitnerium. This VSI is an exploration of the fundamental question: what is the world made from?
Physical Chemistry: A Very Short Introduction
Authors: Atkins Peter
Published: April 2014

With the development of a variety of exciting new areas of research involving computational chemistry, nano- and smart materials, and applications of the recently discovered graphene, there can be no doubt that physical chemistry is a vitally important field. It is also perceived as the most daunting branch of chemistry, being grounded in physics and mathematics and drawing on quantum mechanics, thermodynamics, and statistical thermodynamics. Physical Chemistry: A Very Short Introduction provides a non-technical insight into the central concepts of the field, and explains its relationship to other branches of chemistry, and its important contributions to our understanding of the natural world.
Microeconomics: A Very Short Introduction
Authors: Dixit Avinash
Published: April 2014

Microeconomics — individuals' choices of where to live and work, how much to save, what to buy, and firms' decisions about location, hiring, firing, and investment — involves issues that concern us on a daily basis. But when people think about economics, they tend to place importance on the bigger picture — macroeconomics — including issues such as unemployment, inflation, and the competitiveness of nations. Microeconomics: A Very Short Introduction argues that the microeconomy has a large impact on the economic world. Using real-life examples from around the world, this VSI provides insights into economics from psychology and sociology to explain economic behaviour and rational choice.
Transient Receptor Potential Melastatin 2 Protects Mice against Polymicrobial Sepsis by Enhancing Bacterial Clearance
Authors: Qian XiaoWei , Numata Tomohiro , Zhang Kai , Li CaiXia , Hou JinChao , Mori Yasuo , Fang XiangMing
Published: April 2014

Background:

Recent studies suggest that the transient receptor potential melastatin 2 (TRPM2) channel plays an important role in inflammation and immune response. However, the role and mechanism of TRPM2 in polymicrobial sepsis remain unclear.

Methods:

The authors explored the effects of genetic disruption of TRPM2 on mortality (n = 15), bacterial clearance (n = 6), organ injury, and systemic inflammation during cecal ligation and puncture–induced sepsis. Electrophysiology, immunoblot, bacterial clearance experiment, and quantitative real-time polymerase chain reaction were used to explore the role and mechanism of TRPM2 in sepsis.

Results:

After cecal ligation and puncture, Trpm2-knockout mice had increased mortality compared with wild-type mice (73.3 vs. 40%, P = 0.0289). The increased mortality was associated with increased bacterial burden, organ injury, and systemic inflammation. TRPM2-mediated Ca2+ influx plays an important role in lipopolysaccharide or cecal ligation and puncture–induced heme oxygenase-1 (HO-1) expression in macrophage. HO-1 up-regulation decreased bacterial burden both in wild-type bone marrow–derived macrophages and in cecal ligation and puncture–induced septic wild-type mice. Disruption of TRPM2 decreased HO-1 expression and increased bacterial burden in bone marrow–derived macrophages. Pretreatment of Trpm2-knockout bone marrow–derived macrophages with HO-1 inducer markedly increased HO-1 expression and decreased bacterial burden. Pretreatment of Trpm2-knockout mice with HO-1 inducer reversed the susceptibility of Trpm2-knockout mice to sepsis by enhancing the bacterial clearance. In addition, septic patients with lower monocytic TRPM2 and HO-1 messenger RNA levels had a worse outcome compared with septic patients with normal monocytic TRPM2 and HO-1 messenger RNA levels. TRPM2 levels correlated with HO-1 levels in septic patients (r = 0.675, P = 0.001).

Conclusion:

The study data demonstrate a protective role of TRPM2 in controlling bacterial clearance during polymicrobial sepsis possibly by regulating HO-1 expression.
Bank size, lending paradigms, and usage of Farm Service Agency's guaranteed loan programs
Authors: Dodson Charles
Published: April 2014

Purpose

– An established paradigm in small business lending is segmented by bank size with large banks more likely to lend to large informationally transparent firms while small banks are more likely to lend to small informationally opaque firms. In light of banking consolidation, this market segmentation can have implications for credit availability. Federal loan guarantees, such as those provided by USDA's Farm Service Agency (FSA) may reduce the risks of lending to informationally opaque firms thereby mitigating the impacts of the bank size lending paradigm. This paper aims to discuss these issues.

Design/methodology/approach

– This analysis utilized a binomial logit procedure to determine if there was any empirical evidence that smaller community banks served a unique clientele of farmers when making FSA-guaranteed loans. The analysis relied on a unique data set which incorporated detailed data on farm businesses receiving FSA-guaranteed loans, loan characteristics, as well as information about the originating bank and characteristics of the local credit markets.

Findings

– Results were consistent with the bank size lending paradigm with smaller banks being less likely to engage in fixed-asset lending, and more likely to serve a riskier and less established clientele when making guaranteed loans.

Research limitations/implications

– Data limitations did not permit detailed analysis of banks larger than $250 million in total assets nor for consideration of non-bank lenders. An expansion by these lender groups into serving more informationally opaque borrowers could mitigate any adverse impacts arising from fewer small community banks.

Practical implications

– The results suggested that Federal guarantees do not completely eliminate the relative informational advantages of large and small size banks. And, continued bank consolidation, such that there are fewer small community banks, could result in less credit availability among smaller, less creditworthy farm businesses.

Social implications

– While FSA guarantees may not enhance a large banks propensity to serve informationally opaque farm borrowers, they may enhance the ability of smaller community banks to serve groups specifically targeted through FSA lending programs; the provision of credit to family farmers who, despite being creditworthy, are unable to obtain credit at reasonable rates and terms.

Originality/value

– The analysis examines relationship between bank size and the use of FSA guarantees using a unique data set which incorporated information on FSA-guaranteed loans, farm financial characteristics, along with characteristics of commercial banks which participated in the FSA-guarantee program.
An analysis of risk management tools utilized by Illinois farmers
Authors: Tudor Kerry , Spaulding Aslihan , D. Roy Kayla , Winter Randy
Published: April 2014

Purpose

– The purpose of this paper is to investigate the relationships among choice of risk management tools, perceived effectiveness of risk management tools, self-reported risk attitude, and farm and farmer characteristics.

Design/methodology/approach

– A mail survey was used to collect information about utilization of risk management tools, perceived effectiveness of risk management tools, and factors that could influence choice of risk management tools by Illinois farmers. Cluster analysis, one-way ANOVA, χ2 tests of independence, and multinomial logistic regression were utilized to detect possible relationships among choice of risk management tools, perceived effectiveness of risk management tools, self-reported risk attitude, and farm and farmer characteristics.

Findings

– Multinomial logistic regression analysis revealed that age and gross farm income (GFI) were the strongest predictors of the risk management tool utilization group to which an individual would be assigned. The number of risk management tools utilized decreased with age but increased with GFI. Neither self-reported risk attitude nor education was a significant independent variable in the multinomial logistic regression model, but both were strongly impacted by age. Younger farmers with higher GFI were the most likely users of hedging.

Research limitations/implications

– The results of this study provide support for the idea that farmers who are better able to generate revenue are better able to manage risk, but the direction of causality was not investigated.

Practical implications

– Risk management service providers could benefit from this study as a benchmark for understanding their current and potential farmer clients’ risk management strategies.

Originality/value

– This study used cluster analysis and multinomial logistic regression to address the complexity of decisions regarding multiple risk management tools. The number of tools utilized by individuals was investigated.
Parallel analysis of thermal field in a layered DC cable
Authors: Golebiowski Jerzy , Piotr Bycul Robert
Published: April 2014

Purpose

– The purpose of this paper is to prepare procedures for determination of characteristics and parameters of DC cables on the basis of transient and steady thermal field distribution in their cross-sections.

Design/methodology/approach

– Steady-state current rating was computed iteratively, with the use of steady thermal field distribution in the cable. The iterative process was regulated with respect to this field by changes of the mean surface temperature of the sheath of the cable. It was also controlled with respect to the unknown current rating by deviations of the temperature of the core from the maximum sustained temperature of the insulation (material zone) adjacent to the core. Heating curves were determined (in arbitrarily selected points of the cross-section of the cable) by a parallel algorithm described thoroughly in the first part of the paper. The algorithm was used for computing of transient thermal field distribution throughout the whole cross-section. Thermal time constant distributions were determined by the trapezium rule, where the upper integration limit of respective thermal field distributions was being changed.

Findings

– Using the methods prepared the following characteristics/parameters of the cable were determined: steady-state current rating, spatial-time heating curves, mean thermal time constant distribution. The results were verified and turned to be in conformance with those of the IEC 287 Standard and a commercial software – Nisa v. 16. Speedup and efficiency of the parallel computations were calculated. It was concluded that the parallel computations took less time than the sequential ones.

Research limitations/implications

– The specialized algorithms and software are dedicated to cylindrical DC cables.

Practical implications

– The knowledge of the determined characteristics and parameters contributes to optimal exploitation of a DC cable during its use.

Originality/value

– The algorithms of determination of the steady-state current rating and thermal time constant are original. The software described in the appendix has also been made by the authors.
CFD modelling of air and oxy-coal combustion
Authors: Stęchły Katarzyna , Wecel Gabriel , B. Ingham Derek
Published: April 2014

Purpose

– The main goal of this work was the CFD analysis of air and oxy-coal combustion, in order to develop a validated with experimental measurements model of the combustion chamber. Moreover, the purpose of this paper is to provide information about limitations of the sub-models implemented in commercial CFD code ANSYS Fluent version 13.0 for the oxy-coal combustion simulations. The influence of implementation of the weighted sum of gray gas model (WSGGM) with coefficients updated to oxy-coal combustion environment has been investigated.

Design/methodology/approach

– The sub-models validated with experimental measurements model for the air combustion has been used to predict the oxy-coal combustion case and subsequently the numerical solutions have been compared with the experimental data, which enclose the surface incident radiation (SIR) and the flue gas temperature. To improve the numerical prediction of the oxy-coal combustion process the own routine for calculating properties of the oxy-combustion product has been implemented.

Findings

– The results of numerical simulation of combustion in the air environment fitted within the experimental measurements accuracy. However, the air combustion sub-models implemented for the oxy-coal combustion simulations does not predict the SIR within the experimental data accuracy. The implementation of own routine, which uses the coefficients calculated for oxy-coal combustion environment shows improvement in numerical prediction of oxy-coal combustion.

Originality/value

– The radiative properties of gases in the combustion chamber during oxy-coal combustion calculated using the WSGGM implemented in ANSYS Fluent 13.0 do not predict the SIR within experimental measurement accuracy, however, implementation of WSGGM with updated coefficients provide a reasonable improvement in numerical prediction of SIR in the oxy-coal combustion.
Front tracking approach to modeling binary alloy solidification
Authors: Seredyński Miroslaw , Banaszek Jerzy
Published: April 2014

Purpose

– The purpose of this paper is to endorse the idea of using a special post-calculating front tracking (FT) procedure, along with the enthalpy-porosity front tracking (EP-FT) single continuum model, in order to identify zones of different dendritic microstructures developing in the mushy zone during cooling and solidification of a binary alloy.

Design/methodology/approach

– The 2D and 3D algorithms of the FT approach along with different crystal growth laws were implemented in macroscopic calculations of binary alloy solidification with the identification of different dendrite zones developing during the process.

Findings

– Direct comparison of results predicted by the FT model with that based on the concept of the critical value of the solid volume fraction shows the sensitivity of the latter on an arbitrary assumed value of the dendrite coherency point (DCP). Moreover, for a carefully chosen DCP value the second model provides results that are close to those given by the FT-based approach. It is also observed that the macro-segregation pattern obtained by the proposed method is hardly influenced by chosen dendrite tip kinetics.

Originality/value

– To the best authors’ knowledge, for the first time the 3D FT model has been used along with the enthalpy porosity approach to simulate the development of zones of different dendrite morphology during binary alloy solidification. And, a weak influence of assumed different dendrite tip kinetics on the macro-segregation pattern has been proved, what justifies this underlying assumption of the EP-FT method.
A conjugate axisymmetric model of a high-pressure shock-tube facility
Authors: Lamnaouer Mouna , Kassab Alain , Divo Eduardo , Polley Nolan , Garza-Urquiza Rodrigo , Petersen Eric
Published: April 2014

Purpose

– An axisymmetric shock-tube model of the high-pressure shock-tube facility at the Texas A&M University has been developed. The shock tube is non-conventional with a non-uniform cross-section and features a driver section with a smaller diameter than the driven section. The paper aims to discuss these issues.

Design/methodology/approach

– Computations were carried out based on the finite volume approach and the AUSM+ flux-differencing scheme. The adaptive mesh refinement algorithm was applied to the time-dependent flow fields to accurately capture and resolve the shock and contact discontinuities as well as the very fine scales associated with the viscous effects. The incorporation of a conjugate heat transfer model enhanced the credibility of the results.

Findings

– The shock-tube model is validated with simulation of the bifurcation phenomenon and with experimental data. The model is shown to be capable of accurately simulating the shock and expansion wave propagations and reflections as well as the flow non-uniformities behind the reflected shock wave as a result of reflected shock/boundary layer interaction or bifurcation. The pressure profiles behind the reflected shock wave agree with the experimental results.

Originality/value

– This paper presents one of the first studies to model the entire flow field history of a non-uniform diameter shock tube with a conjugate heat transfer model beginning from the bursting of the diaphragm while simultaneously resolving the fine features of the reflected shock-boundary layer interaction and the post-shock region near the end-wall, at conditions useful for chemical kinetics experiments. An important discovery from this study is the possible existence of hot spots in the end-wall region that could lead to early non-homogeneous ignition events. More experimental and numerical work is needed to quantify the hot spots.
A new operational matrix method based on the Bernstein polynomials for solving the backward inverse heat conduction problems
Authors: Rostamy Davood , Karimi Kobra
Published: April 2014

Purpose

– The purpose of this paper is to introduce a novel approach based on the high-order matrix derivative of the Bernstein basis and collocation method and its employment to solve an interesting and ill-posed model in the heat conduction problems, homogeneous backward heat conduction problem (BHCP).

Design/methodology/approach

– By using the properties of the Bernstein polynomials the problems are reduced to an ill-conditioned linear system of equations. To overcome the unstability of the standard methods for solving the system of equations an efficient technique based on the Tikhonov regularization technique with GCV function method is used for solving the ill-condition system.

Findings

– The presented numerical results through table and figures demonstrate the validity and applicability and accuracy of the technique.

Originality/value

– A novel method based on the high-order matrix derivative of the Bernstein basis and collocation method is developed and well-used to obtain the numerical solutions of an interesting and ill-posed model in heat conduction problems, homogeneous BHCP with high accuracy.
3-D periodic CFD model of the heating system in a coke oven battery
Authors: Smolka Jacek , Fic Adam , J. Nowak Andrzej , Kosyrczyk Ludwik
Published: April 2014

Purpose

– The purpose of this paper is to develop a 3-D fully transient numerical model of the heat and fluid flow associated with the chemical reactions that occur in the heating system of the coke oven battery. As a result, the model can be used to provide data for the control system of the battery to reduce energy consumption and emissions and to obtain a product of the desired quality.

Design/methodology/approach

– In the proposed model, an accurate representation of the heating flue geometry, the volumetric heat sources as a result of the coke oven gas combustion, the temperature- and mole fraction-dependent properties of the gases were taken into account. The most important part of the model was the unsteady boundary condition definition that allowed the modeling of the periodic heat delivery to the two oven heating walls, both in the coking and the reversion cycles.

Findings

– The temperatures obtained using the computational fluid dynamics (CFD) model showed the same pattern of temperature variations as that observed in the experiments. It was also found that the quality of the temperature variation predictions was highly dependent on the radiation model settings.

Originality\value

– The CFD models available in the literature describe the steady or pseudo-steady state operation of the heating system of the coke oven battery. The model developed in this work fully reflects the unsteady character of this heating system. Moreover, the proposed model is prepared for coupling with a model of the coking process that occurs in the two neighboring coke oven chambers.
CFD flow analysis in the centrifugal vortex pump
Authors: Mihalić Tihomir , Guzović Zvonimir , Predin Andrej
Published: April 2014

Purpose

– Aging of the oil wells leads to a decrease in reservoir pressure and also to an increase in the water, gas and abrasive particles content. Therefore, there is a need for the oil pumps exploitation characteristics improvements. This paper aims to generate a valuable numerical model which will provide a useful tool to study various cases.

Design/methodology/approach

– Computational fluid dynamics (CFD) analysis of the generation of so-called coherent structures of eddies and turbulence in the peripheral area of the vortex rotor mounted at the back side of centrifugal rotor was undertaken. After detailed analysis of the influence of the used turbulence models on the results, a hybrid turbulent model Detached Eddies Simulation (DES) was chosen as the most suitable.

Findings

– Numerical control volume method with unsteady solver and DES turbulence model was proven to be valuable tool for flow analysis in the centrifugal pumps. Having in mind that DES turbulence model consumes much less computational time than large eddies turbulence model, this is a very useful fact that resulted from this research.

Practical implications

– The proven numerical model is robust and reliable enough to become a standard method in simulating flow and other physical phenomena occurring in centrifugal pumps and similar turbo machines. This makes it possible to easily research different factors that influence their performances.

Originality/value

– Comprehensive experimental and CFD study was performed which made it possible to conduct detailed validation and verification of described CFD model.
A combination of Crouzeix-Raviart, Discontinuous Galerkin and MPFA methods for buoyancy-driven flows
Authors: Younes Anis , Makradi Ahmed , Zidane Ali , Shao Qian , Bouhala Lyazid
Published: April 2014

Purpose

– The purpose of this paper is to develop an efficient non-iterative model combining advanced numerical methods for solving buoyancy-driven flow problems.

Design/methodology/approach

– The solution strategy is based on two independent numerical procedures. The Navier-Stokes equation is solved using the non-conforming Crouzeix-Raviart (CR) finite element method with an upstream approach for the non-linear convective term. The advection-diffusion heat equation is solved using a combination of Discontinuous Galerkin (DG) and Multi-Point Flux Approximation (MPFA) methods. To reduce the computational time due to the coupling, the authors use a non-iterative time stepping scheme where the time step length is controlled by the temporal truncation error.

Findings

– Advanced numerical methods have been successfully combined to solve buoyancy-driven flow problems on unstructured triangular meshes. The accuracy of the results has been verified using three test problems: first, a synthetic problem for which the authors developed a semi-analytical solution; second, natural convection of air in a square cavity with different Rayleigh numbers (103-108); and third, a transient natural convection problem of low Prandtl fluid with horizontal temperature gradient in a rectangular cavity.

Originality/value

– The proposed model is the first to combine advanced numerical methods (CR, DG, MPFA) for buoyancy-driven flow problems. It is also the first to use a non-iterative time stepping scheme based on local truncation error control for such coupled problems. The developed semi analytical solution based on Fourier series is also novel.
Leveraging the power of online social networks: a contingency approach
Authors: Fen Crystal Yap Sheau , Kwai Choi Lee Christina
Published: April 2014

Purpose

– The purpose of this paper is to examine online community loyalty through an extension of the theory of planned behaviour by incorporating motivational drivers of enjoyment and compatibility and the moderating role of consumer traits.

Design/methodology/approach

– Data were collected using an online survey of 382 Facebook users in Malaysia. Structural equation modelling was used to assess the hypothesised relationships.

Findings

– Findings reveal that individuals’ attitude towards social network usage is associated with three factors: social influence, compatibility and enjoyment; attitude and usage behaviour are the determinants of online community loyalty. In addition, moderating effects are found in innovativeness and social network user experience.

Research limitations/implications

– Generalisation of the results to other contexts or populations should be made with caution given the study's focus on Facebook and its use of non-probability sampling. Future research can cross-validate or extend the theoretical model across different samples and/or virtual community settings.

Practical implications

– This study highlights the importance of designing online brand community web sites which are not only appealing and enjoyable but also acts as an outlet for its members to build upon their experiences and showcase their innovativeness.

Originality/value

– This research contributes to a better understanding of how personal factors can either strengthen or attenuate a member's loyalty to his or her online community. The research framework developed in this study can serve as a springboard for future research to examine other virtual community engagement such as blogging, online advertising and online public relation activities.
Knowledge sharing and competitive intelligence
Authors: Luu Tuan
Published: April 2014

Purpose

– This research excursion through shipping companies in Vietnam sought to investigate whether organizational culture, ethics, and emotional intelligence influence knowledge sharing, which in turn enhances competitive intelligence scanning. This paper aims to discuss the above issue.

Design/methodology/approach

– In total, 401 responses returned from self-administered structured questionnaires relayed to 635 middle level managers were processed through structural equation modeling approach to test hypotheses.

Findings

– Knowledge sharing was proved to positively relate to clan, market, or adhocracy culture, ethics of care, and high level of emotional intelligence. Knowledge sharing also shows a positive effect on competitive intelligence scanning.

Originality/value

– For competitive intelligence scanning to be effective, knowledge should be shared among organizational members, which necessitates the three building blocks: supportive knowledge sharing culture (clan, market, or adhocracy culture), ethics or care, and heightened emotional intelligence.
Managing relationship marketing in the food service industry
Authors: Firdaus Abdullah , Kanyan Agnes
Published: April 2014

Purpose

– The purpose of this paper is to propos a new measuring instrument for relationship marketing which is uniquely designed for the foodservice industry. In particular, the underlying dimensions of relationship marketing as perceived by customers are identified, and strategies for the enhancement of relationship marketing program are put forward.

Design/methodology/approach

– The proposed 31-item instrument has been empirically tested for unidimensionality, reliability and validity using both exploratory and confirmatory factor analysis

Findings

– A factorial analysis suggests that relationship marketing is a multidimensional construct consisting of four key dimensions namely communication, trust, empathy and commitment.

Practical implications

– Communication emphasizes the necessity to communicate in understandable way; trust refers to the ability to inspire confidence; empathy stresses on the importance of exhibiting sympathy and reassurance; and commitment describes the desire to provide excellent service. A subsequent multiple regression analysis reveals that all the dimensions are positively correlated with customer loyalty and trust was the most important dimension.

Originality/value

– Building strong relationships with customers to gain competitive advantage and customer loyalty is crucial for survival and success in today's business environment. As competition is becoming more intense, customers are increasingly demanding and price sensitive. Although the relationship marketing discipline is relatively well researched, the measuring instrument is limited and practically non-existent in the foodservice industry.
Chloroquine interferes with dengue‐2 virus replication in U937 cells
Authors: Farias Kleber Juvenal Silva , Machado Paula Renata Lima , de Almeida Junior Renato Ferreira , de Aquino Ana Alice , da Fonseca Benedito Antônio Lopes
Published: April 2014

The objective of this study was to investigate the use of chloroquine (CLQ) as an antiviral agent against dengue. Chloroquine, an amine acidotropic drug known to affect intracellular exocytic pathways by increasing endosomal pH, was used in the in vitro treatment of U937 cells infected with dengue virus type 2 (DENV‐2). Viral replication was assessed by quantification of virus produced through detection of copy numbers of DENV‐2 RNA, plaque assay and indirect immunofluorescence. qRT‐PCR and plaque assays were used to quantify the DENV‐2 load in infected U937 cells after CLQ treatment. It was found that a dose of 50 μg/mL of CLQ was not toxic to the cells and resulted in significantly less virus production in infected U937 cells than occurred in untreated cells. In the present work, CLQ was effective against DENV‐2 replication in U937 cells, and also caused a statistically significant reduction in expression of proinflammatory cytokines. The present study indicates that CLQ may be used to reduce viral yield in U937 cells.
Temperature‐dependent variation in alternative migratory tactics and its implications for fitness and population dynamics in a salmonid fish
Authors: Morita Kentaro , Tamate Tsuyoshi , Kuroki Mari , Nagasawa Toru
Published: April 2014

Temperature‐driven life‐history modifications by adaptation occur in ectotherms, and therefore, life‐history modifications by adaptation need to be taken into consideration when predicting population responses to the climate change.

Partial migration is a common form of life‐history diversity in which a population contains both migratory and resident behaviours. Salmonid fish exhibit a wide range of life‐history diversity and, in particular, partial migration. We evaluated the effect of temperature‐driven life‐history modifications on population dynamics in partially migratory masu salmon (Oncorhynchus masou) by field observations and theoretical models.

Field observations revealed that spatial patterns of alternative migratory tactics were associated with temperature gradients. The occurrence of resident males increased, whereas the proportion of migrant males and the proportion of delayed migrants including both sexes decreased with increasing temperature and, thereby, with improved early growth conditions.

The expected fitness for each migratory tactic was computed in a life‐history model with early growth conditions as a function. Individual fitness was maximized by adopting resident tactics under favourable early growth conditions, early migrant tactics under intermediate early growth conditions and delayed migrant tactics under unfavourable early growth conditions. The results suggest that individuals exhibited a status‐dependent conditional strategy, that is, the adoption of alternative migratory tactics is influenced by the status of individuals to make the best of a situation.

A simulation model suggests that increased residency by males to increased temperature leads to a substantial decrease in the number of migrants. Moreover, the decrease in the number of delayed (older) migrants with increasing temperature magnified fluctuations in abundance. Our findings indicate the importance of temperature‐driven life‐history modifications for predicting dynamics of natural populations under climate warming.
Forest structure drives global diversity of primates
Authors: Gouveia Sidney F. , Villalobos Fabricio , Dobrovolski Ricardo , Beltrão‐Mendes Raone , Ferrari Stephen F.
Published: April 2014

Geographic gradients in the species richness of non‐human primates have traditionally been attributed to the variation in forest productivity (related to precipitation levels), although an all‐inclusive, global‐scale analysis has never been conducted.

We perform a more comprehensive test on the role of precipitation and biomass production and propose an alternative hypothesis – the variation in vertical structure of forest habitats as measured by forest canopy height – in determining primate species richness on a global scale.

Considering the potential causal relationships among precipitation, productivity and forest structure, we arranged these variables within a path framework to assess their direct and indirect associations with the pattern of primate species richness using structural equation modelling. The analysis also accounted for the influence of spatial autocorrelation in the relationships and assessed possible historical differences among biogeographical regions.

The path coefficients indicate that forest canopy height (used as a proxy for vertical forest structure) is a better predictor of primate species richness than either precipitation or productivity on both global and continental scales. The only exception was Asia, where precipitation prevailed, albeit independently from productivity or forest structure. The influence of spatially structured processes varied markedly among biogeographical regions.

Our results challenge the traditional rainfall‐based viewpoint in favour of forest distribution and structure as primary drivers of primate species richness, which aggregate potential effects from both climatic factors and habitat complexity. These findings may support predictions of the impact of forest removal on primate species richness.
Using filter‐based community assembly models to improve restoration outcomes
Authors: Hulvey Kristin B. , Aigner Paul A.
Published: April 2014

Ecological filter models derived from community assembly theory can inform restoration planning by highlighting management actions most likely to affect community composition. Despite growing interest in these models, many restoration studies solely manipulate a single assembly filter – the biotic filter by altering interspecific competition – while ignoring abiotic and dispersal filters that may also influence restoration success.

To examine how manipulating all three assembly filters (biotic, abiotic, dispersal) affected restoration in an annual‐type grassland, we seeded native forbs from the same functional group as a target invader to increase biotic resistance to invasion (biotic filter), cut standing biomass and either removed it or returned it to plots as litter to alter light conditions (abiotic filter), and added native forbs at different seeding rates to alter density of establishing native populations (dispersal filter). We measured grassland restoration success by recording native species and invader cover in plots.

The addition of native species with phenological and morphological traits similar to the target invader reduced invasion and increased native populations, but only in litter‐free plots when high densities of native seed were added.

Seeding two species with functional traits similar to the invader was more effective for achieving restoration goals than seeding just one functionally similar species. As such, trait differences among restoration species, even species belonging to the same functional group, may increase biotic resistance to invasion in restored communities.

Litter removal altered native–invader interactions. When litter was left on the plots, added natives did not reduce invader cover. However, when litter was removed, added natives led to declines in invader cover.

Increasing native seeding rates led to larger native populations and increased invasion resistance.

Synthesis and applications. In this study, simultaneously manipulating biotic, abiotic and dispersal filters was necessary to optimize grassland restoration outcomes. In particular, the biotic filter only contributed to successful restoration outcomes under abiotic and dispersal conditions that were created through management actions specifically targeting these two additional filters. Restoration planning based on filter models should incorporate actions that target all three assembly filters, rather than solely focusing on the biotic filter.
Classic paradigms in a novel environment: inserting food web and productivity lessons from rocky shores and saltmarshes into biogenic reef restoration
Authors: Fodrie F. Joel , Rodriguez Antonio B. , Baillie Christopher J. , Brodeur Michelle C. , Coleman Sara E. , Gittman Rachel K. , Keller Danielle A. , Kenworthy Matthew D. , Poray Abigail K. , Ridge Justin T. , Theuerkauf Ethan J. , Lindquist Niels. L.
Published: April 2014

Gradients in competition and predation that regulate communities should guide biogenic habitat restoration, while restoration ecology provides opportunities to address fundamental questions regarding food web dynamics via large‐scale field manipulations.

We restored oyster reefs across an aerial exposure gradient (shallow‐subtidal‐to‐mid‐intertidal) to explore how vertical gradients in natural settlement, growth and interspecific interactions affected the trajectory of man‐made shellfish reefs.

We recorded nearly an order‐of‐magnitude higher oyster settlement on the deepest (subtidal) reefs, but within a year abundance patterns reversed, and oyster densities were ultimately highest on the shallowest (intertidal) reefs by over an order‐of‐magnitude.

This reversal was due to (i) significantly elevated survivorship on intertidal reefs and (ii) larger surviving oysters on intertidal reefs. These patterns are likely to have developed from greater levels of biofouling and predator abundance (e.g. stone crabs, gastropods) on deeper reefs where aerial exposure was <5% of the monthly tidal cycle.

Synthesis and applications. The success of restoration initiatives involving habitat‐forming species can be enhanced by accounting for the biotic interactions that regulate population fitness. In littoral systems, vertical gradients in predation, competition and disturbance can be exploited to guide restoration of vegetated (e.g. mangrove, seagrass) or biogenic reef habitats. In particular, our results demonstrate that paradigms of vertical zonation learned from the rocky intertidal and saltmarshes also describe the fate of restored shellfish reefs. As with rocky shores, the lower vertical limit of adult oyster distribution in our study system was most likely driven by predatory and competitive (i.e. smothering) interactions, with a threshold depth at c. 5% daily aerial exposure. Below this depth, experimentally restored reefs failed completely. As with Spartina saltmarsh, accumulation of oyster biomass was greatest at an intermediate vertical position relative to mean sea level (i.e. mid‐to‐low intertidal). Our developing model proscribes a vertical ‘hot spot’ for restoration efforts to maximize biogenic reef fitness and production.