bluuebunny/crossref_metadata_2025 huggingface dataset:
Halosimplex pelagicum sp. nov. and Halosimplex rubrum sp. nov., isolated from salted brown alga Laminaria, and emended description of the genus Halosimplex
Authors: Han Dong , Cui Heng-Lin
Published: September 2013

Two halophilic archaeal strains, R2T and R27T, were isolated from the brown alga Laminaria produced at Dalian, Liaoning Province, China. Both had pleomorphic cells that lysed in distilled water, stained Gram-negative and formed red-pigmented colonies. They grew optimally at 42 °C, pH 7.0 and in the presence of 3.1–3.4 M NaCl and 0.03–0.5 M Mg2+. The major polar lipids of the two strains were phosphatidylglycerol (PG), phosphatidylglycerol phosphate methyl ester (PGP-Me) and four major glycolipids chromatographically identical to those of

Halosimplex carlsbadense

JCM 11222T. 16S rRNA gene analysis revealed that each strain had two dissimilar 16S rRNA genes and both strains were phylogenetically related to

Halosimplex carlsbadense

JCM 11222T (92.7–98.8 % similarities). The rpoB′ gene similarities between strains R2T and R27T and between these strains and

Halosimplex carlsbadense

JCM 11222T were 95.7 %, 96.1 % and 95.8 %, respectively. The DNA G+C contents of strains R2T and R27T were 62.5 mol% and 64.0 mol%, respectively. The DNA–DNA hybridization values between strains R2T and R27T and between the two strains and

Halosimplex carlsbadense

JCM 11222T were 43 %, 52 % and 47 %, respectively. It was concluded that strain R2T ( = CGMCC 1.10586T = JCM 17263T) and strain R27T ( = CGMCC 1.10591T = JCM 17268T) represent two novel species of the genus

Halosimplex

, for which the names Halosimplex pelagicum sp. nov. and Halosimplex rubrum sp. nov. are proposed. An emended description of the genus
Halosimplex
is also presented.
Possible contributions of a novel form of synaptic plasticity inAplysiato reward, memory, and their dysfunctions in mammalian brain
Authors: Hawkins Robert D.
Published: September 2013

Recent studies inAplysiahave identified a new variation of synaptic plasticity in which modulatory transmitters enhance spontaneous release of glutamate, which then acts on postsynaptic receptors to recruit mechanisms of intermediate- and long-term plasticity. In this review I suggest the hypothesis that similar plasticity occurs in mammals, where it may contribute to reward, memory, and their dysfunctions in several psychiatric disorders. InAplysia, spontaneous release is enhanced by activation of presynaptic serotonin receptors, but presynaptic D1 dopamine receptors or nicotinic acetylcholine receptors could play a similar role in mammals. Those receptors enhance spontaneous release of glutamate in hippocampus, entorhinal cortex, prefrontal cortex, ventral tegmental area, and nucleus accumbens. In all of those brain areas, glutamate can activate postsynaptic receptors to elevate Ca2+and engage mechanisms of early-phase long-term potentiation (LTP), including AMPA receptor insertion, and of late-phase LTP, including protein synthesis and growth. Thus, presynaptic receptors and spontaneous release may contribute to postsynaptic mechanisms of plasticity in brain regions involved in reward and memory, and could play roles in disorders that affect plasticity in those regions, including addiction, Alzheimer’s disease, schizophrenia, and attention deficit hyperactivity disorder (ADHD).
Understanding cognitive deficits in Parkinson’s disease: lessons from preclinical animal models
Authors: Solari Nicola , Bonito-Oliva Alessandra , Fisone Gilberto , Brambilla Riccardo
Published: September 2013

Parkinson’s disease (PD) has been, until recently, mainly defined by the presence of characteristic motor symptoms, such as rigidity, tremor, bradykinesia/akinesia, and postural instability. Accordingly, pharmacological and surgical treatments have so far addressed these motor disturbances, leaving nonmotor, cognitive deficits an unmet clinical condition. At the preclinical level, the large majority of studies aiming at defining mechanisms and testing novel therapies have similarly focused on the motor aspects of PD. Unfortunately, deterioration of the executive functions, such as attention, recognition, working memory, and problem solving, often appear in an early, premotor phase of the disease and progressively increase in intensity, negatively affecting the quality of life of ∼50%–60% of PD patients. At present, the cellular mechanisms underlying cognitive impairments in PD patients are largely unknown and an adequate treatment is still missing. The preclinical research has recently developed new animal models that may open new perspectives for a more integrated approach to the treatment of both motor and cognitive symptoms of the disease. This review will provide an overview on the cognitive symptoms occurring in early PD patients and then focus on the rodent and nonhuman primate models so far available for the study of discriminative and spatial memory attention and learning abilities related to this pathological condition.
Complex structure of type VI peptidoglycan muramidase effector and a cognate immunity protein
Authors: Wang Tianyu , Ding Jinjing , Zhang Ying , Wang Da-Cheng , Liu Wei
Published: September 2013

The type VI secretion system (T6SS) is a bacterial protein-export machine that is capable of delivering virulence effectors between Gram-negative bacteria. The T6SS ofPseudomonas aeruginosatransports two lytic enzymes, Tse1 and Tse3, to degrade cell-wall peptidoglycan in the periplasm of rival bacteria that are competing for nichesviaamidase and muramidase activities, respectively. Two cognate immunity proteins, Tsi1 and Tsi3, are produced by the bacterium to inactivate the two antibacterial effectors, thereby protecting its siblings from self-intoxication. Recently, Tse1–Tsi1 has been structurally characterized. Here, the structure of the Tse3–Tsi3 complex is reported at 1.9 Å resolution. The results reveal that Tse3 contains a C-terminal catalytic domain that adopts a soluble lytic transglycosylase (SLT) fold in which three calcium-binding sites were surprisingly observed close to the catalytic Glu residue. The electrostatic properties of the substrate-binding groove are also distinctive from those of known structures with a similar fold. All of these features imply that a unique catalytic mechanism is utilized by Tse3 in cleaving glycosidic bonds. Tsi3 comprises a single domain showing a β-sandwich architecture that is reminiscent of the immunoglobulin fold. Three loops of Tsi3 insert deeply into the groove of Tse3 and completely occlude its active site, which forms the structural basis of Tse3 inactivation. This work is the first crystallographic report describing the three-dimensional structure of the Tse3–Tsi3 effector–immunity pair.
Structure of the JmjC-domain-containing protein JMJD5
Authors: Wang Haipeng , Zhou Xing , Wu Minhao , Wang Chengliang , Zhang Xiaoqin , Tao Yue , Chen Nini , Zang Jianye
Published: September 2013

The post-translational modification of histone tails is the principal process controlling epigenetic regulation in eukaryotes. The lysine methylation of histones is dynamically regulated by two distinct classes of enzymes: methyltransferases and demethylases. JMJD5, which plays an important role in cell-cycle progression, circadian rhythms and embryonic cell proliferation, has been shown to be a JmjC-domain-containing histone demethylase with enzymatic activity towards H3K36me2. Here, the crystal structure of human JMJD5 lacking the N-terminal 175 amino-acid residues is reported. The structure showed that the Gln275, Trp310 and Trp414 side chains might block the insertion of methylated lysine into the active centre of JMJD5, suppressing the histone demethylase activity of the truncated JMJD5 construct. A comparison of the structure of JMJD5 with that of FIH, a well characterized protein hydroxylase, revealed that human JMJD5 might function as a protein hydroxylase. The interaction between JMJD5 and the core histone octamer proteins indicated that the histone proteins could be potential substrates for JMJD5.
On effective and optical resolutions of diffraction data sets
Authors: Urzhumtseva Ludmila , Klaholz Bruno , Urzhumtsev Alexandre
Published: September 2013

In macromolecular X-ray crystallography, diffraction data sets are traditionally characterized by the highest resolutiondhighof the reflections that they contain. This measure is sensitive to individual reflections and does not refer to the eventual data incompleteness and anisotropy; it therefore does not describe the data well. A physically relevant and robust measure that provides a universal way to define the `actual' effective resolutiondeffof a data set is introduced. This measure is based on the accurate calculation of the minimum distance between two immobile point scatterers resolved as separate peaks in the Fourier map calculated with a given set of reflections. This measure is applicable to any data set, whether complete or incomplete. It also allows characterizion of the anisotropy of diffraction data sets in whichdeffstrongly depends on the direction. Describing mathematical objects, the effective resolutiondeffcharacterizes the `geometry' of the set of measured reflections and is irrelevant to the diffraction intensities. At the same time, the diffraction intensities reflect the composition of the structure from physical entities: the atoms. The minimum distance for the atoms typical of a given structure is a measure that is different from and complementary todeff; it is also a characteristic that is complementary to conventional measures of the data-set quality. Following the previously introduced terms, this value is called the optical resolution,dopt. The optical resolution as defined here describes the separation of the atomic images in the `ideal' crystallographic Fourier map that would be calculated if the exact phases were known. The effective and optical resolution, as formally introduced in this work, are of general interest, giving a common `ruler' for all kinds of crystallographic diffraction data sets.
High-resolution structure of an atypical α-phosphoglucomutase related to eukaryotic phosphomannomutases
Authors: Nogly Przemyslaw , Matias Pedro M. , de Rosa Matteo , Castro Rute , Santos Helena , Neves Ana Rute , Archer Margarida
Published: September 2013

The first structure of a bacterial α-phosphoglucomutase with an overall fold similar to eukaryotic phosphomannomutases is reported. Unlike most α-phosphoglucomutases within the α-D-phosphohexomutase superfamily, it belongs to subclass IIb of the haloacid dehalogenase superfamily (HADSF). It catalyzes the reversible conversion of α-glucose 1-phosphate to glucose 6-phosphate. The crystal structure of α-phosphoglucomutase fromLactococcus lactis(APGM) was determined at 1.5 Å resolution and contains a sulfate and a glycerol bound at the enzyme active site that partially mimic the substrate. A dimeric form of APGM is present in the crystal and in solution, an arrangement that may be functionally relevant. The catalytic mechanism of APGM and its strict specificity towards α-glucose 1-phosphate are discussed.
Rv2969c, essential for optimal growth inMycobacterium tuberculosis, is a DsbA-like enzyme that interacts with VKOR-derived peptides and has atypical features of DsbA-like disulfide oxidases
Authors: Premkumar Lakshmanane , Heras Begoña , Duprez Wilko , Walden Patricia , Halili Maria , Kurth Fabian , Fairlie David P. , Martin Jennifer L.
Published: September 2013

The bacterial disulfide machinery is an attractive molecular target for developing new antibacterials because it is required for the production of multiple virulence factors. The archetypal disulfide oxidase proteins inEscherichia coli(Ec) are DsbA and DsbB, which together form a functional unit: DsbA introduces disulfides into folding proteins and DsbB reoxidizes DsbA to maintain it in the active form. InMycobacterium tuberculosis(Mtb), no DsbB homologue is encoded but a functionally similar but structurally divergent protein, MtbVKOR, has been identified. Here, the Mtb protein Rv2969c is investigated and it is shown that it is the DsbA-like partner protein of MtbVKOR. It is found that it has the characteristic redox features of a DsbA-like protein: a highly acidic catalytic cysteine, a highly oxidizing potential and a destabilizing active-site disulfide bond. Rv2969c also has peptide-oxidizing activity and recognizes peptide segments derived from the periplasmic loops of MtbVKOR. Unlike the archetypal EcDsbA enzyme, Rv2969c has little or no activity in disulfide-reducing and disulfide-isomerase assays. The crystal structure of Rv2969c reveals a canonical DsbA fold comprising a thioredoxin domain with an embedded helical domain. However, Rv2969c diverges considerably from other DsbAs, including having an additional C-terminal helix (H8) that may restrain the mobility of the catalytic helix H1. The enzyme is also characterized by a very shallow hydrophobic binding surface and a negative electrostatic surface potential surrounding the catalytic cysteine. The structure of Rv2969c was also used to model the structure of a paralogous DsbA-like domain of the Ser/Thr protein kinase PknE. Together, these results show that Rv2969c is a DsbA-like protein with unique properties and a limited substrate-binding specificity.
The structure of a glycoside hydrolase family 81 endo-β-1,3-glucanase
Authors: Zhou Peng , Chen Zhongzhou , Yan Qiaojuan , Yang Shaoqing , Hilgenfeld Rolf , Jiang Zhengqiang
Published: September 2013

Endo-β-1,3-glucanases catalyze the hydrolysis of β-1,3-glycosidic linkages in glucans. They are also responsible for rather diverse physiological functions such as carbon utilization, cell-wall organization and pathogen defence. Glycoside hydrolase (GH) family 81 mainly consists of β-1,3-glucanases from fungi, higher plants and bacteria. A novel GH family 81 β-1,3-glucanase gene (RmLam81A) fromRhizomucor mieheiwas expressed inEscherichia coli. PurifiedRmLam81A was crystallized and the structure was determined in two crystal forms (form I-free and form II-Se) at 2.3 and 2.0 Å resolution, respectively. Here, the crystal structure of a member of GH family 81 is reported for the first time. The structure ofRmLam81A is greatly different from all endo-β-1,3-glucanase structures available in the Protein Data Bank. The overall structure of theRmLam81A monomer consists of an N-terminal β-sandwich domain, a C-terminal (α/α)6domain and an additional domain between them. Glu553 and Glu557 are proposed to serve as the proton donor and basic catalyst, respectively, in a single-displacement mechanism. In addition, Tyr386, Tyr482 and Ser554 possibly contribute to both the position or the ionization state of the basic catalyst Glu557. The first crystal structure of a GH family 81 member will be helpful in the study of the GH family 81 proteins and endo-β-1,3-glucanases.
High-resolution structure of a papaya plant-defence barwin-like protein solved by in-house sulfur-SAD phasing
Authors: Huet Joëlle , Teinkela Mbosso Emmanuel Jean , Soror Sameh , Meyer Franck , Looze Yvan , Wintjens René , Wohlkönig Alexandre
Published: September 2013

The first crystal structure of a barwin-like protein, named carwin, has been determined at high resolution by single-wavelength anomalous diffraction (SAD) phasing using the six intrinsic S atoms present in the protein. The barwin-like protein was purified fromCarica papayalatex and crystallized in the orthorhombic space groupP212121. Using in-house Cu Kα X-ray radiation, 16 cumulative diffraction data sets were acquired to increase the signal-to-noise level and thereby the anomalous scattering signal. A sequence-database search on the papaya genome identified two carwin isoforms of 122 residues in length, both containing six S atoms that yield an estimated Bijvoet ratio of 0.93% at 1.54 Å wavelength. A systematic analysis of data quality and redundancy was performed to assess the capacity to locate the S atoms and to phase the data. It was observed that the crystal decay was low during data collection and that successful S-SAD phasing could be obtained with a relatively low data multiplicity of about 7. Using a synchrotron source, high-resolution data (1 Å) were collected from two different crystal forms of the papaya latex carwin. The refined structures showed a central β-barrel of six strands surrounded by several α-helices and loops. The β-barrel of carwin appears to be a common structural module that is shared within several other unrelated proteins. Finally, the possible biological function of the protein is discussed.
Improving experimental phases for strong reflections prior to density modification
Authors: Uervirojnangkoorn Monarin , Hilgenfeld Rolf , Terwilliger Thomas C. , Read Randy J.
Published: September 2013

Experimental phasing of diffraction data from macromolecular crystals involves deriving phase probability distributions. These distributions are often bimodal, making their weighted average, the centroid phase, improbable, so that electron-density maps computed using centroid phases are often non-interpretable. Density modification brings in information about the characteristics of electron density in protein crystals. In successful cases, this allows a choice between the modes in the phase probability distributions, and the maps can cross the borderline between non-interpretable and interpretable. Based on the suggestions by Vekhter [Vekhter (2005),Acta Cryst.D61, 899–902], the impact of identifying optimized phases for a small number of strong reflections prior to the density-modification process was investigated while using the centroid phase as a starting point for the remaining reflections. A genetic algorithm was developed that optimizes the quality of such phases using the skewness of the density map as a target function. Phases optimized in this way are then used in density modification. In most of the tests, the resulting maps were of higher quality than maps generated from the original centroid phases. In one of the test cases, the new method sufficiently improved a marginal set of experimental SAD phases to enable successful map interpretation. A computer program,SISA, has been developed to apply this method for phase improvement in macromolecular crystallography.
Structural characterization of gephyrin by AFM and SAXS reveals a mixture of compact and extended states
Authors: Sander Bodo , Tria Giancarlo , Shkumatov Alexander V. , Kim Eun-Young , Grossmann J. Günter , Tessmer Ingrid , Svergun Dmitri I. , Schindelin Hermann
Published: September 2013

Gephyrin is a trimeric protein involved in the final steps of molybdenum-cofactor (Moco) biosynthesis and in the clustering of inhibitory glycine and GABAAreceptors at postsynaptic specializations. Each protomer consists of stably folded domains (referred to as the G and E domains) located at either terminus and connected by a proteolytically sensitive linker of ∼150 residues. Both terminal domains can oligomerize in their isolated forms; however, in the context of the full-length protein only the G-domain trimer is permanently present, whereas E-domain dimerization is prevented. Atomic force microscopy (AFM) and small-angle X-ray scattering (SAXS) reveal a high degree of flexibility in the structure of gephyrin. The results imply an equilibrium between compact and extended conformational states in solution, with a preference for compact states. CD spectroscopy suggests that a partial compaction is achieved by interactions of the linker with the G and E domains. Taken together, the data provide a rationale for the role of the linker in the overall structure and the conformational dynamics of gephyrin.
Determination of the GH3.12 protein conformation through HPLC-integrated SAXS measurements combined with X-ray crystallography
Authors: Round Adam , Brown Elizabeth , Marcellin Romain , Kapp Ulrike , Westfall Corey S. , Jez Joseph M. , Zubieta Chloe
Published: September 2013

The combination of protein crystallography and small-angle X-ray scattering (SAXS) provides a powerful method to investigate changes in protein conformation. These complementary structural techniques were used to probe the solution structure of the apo and the ligand-bound forms of theArabidopsis thalianaacyl acid–amido synthetase GH3.12. This enzyme is part of the extensive GH3 family and plays a critical role in the regulation of plant hormones through the formation of amino-acid-conjugated hormone productsviaan ATP-dependent reaction mechanism. The enzyme adopts two distinct C-terminal domain orientations with `open' and `closed' active sites. Previous studies suggested that ATP only binds in the open orientation. Here, the X-ray crystal structure of GH3.12 is presented in the closed conformation in complex with the nonhydrolysable ATP analogue AMPCPP and the substrate salicylate. Using on-line HPLC purification combined with SAXS measurements, the most likely apo and ATP-bound protein conformations in solution were determined. These studies demonstrate that the C-terminal domain is flexible in the apo form and favours the closed conformation upon ATP binding. In addition, these data illustrate the efficacy of on-line HPLC purification integrated into the SAXS sample-handling environment to reliably monitor small changes in protein conformation through the collection of aggregate-free and highly redundant data.
The IMAGINE instrument: first neutron protein structure and new capabilities for neutron macromolecular crystallography
Authors: Meilleur Flora , Munshi Parthapratim , Robertson Lee , Stoica Alexandru D. , Crow Lowell , Kovalevsky Andrey , Koritsanszky Tibor , Chakoumakos Bryan C. , Blessing Robert , Myles Dean A. A.
Published: September 2013

The first high-resolution neutron protein structure of perdeuterated rubredoxin fromPyrococcus furiosus(PfRd) determined using the new IMAGINE macromolecular neutron crystallography instrument at the Oak Ridge National Laboratory is reported. Neutron diffraction data extending to 1.65 Å resolution were collected from a relatively small 0.7 mm3PfRd crystal using 2.5 d (60 h) of beam time. The refined structure contains 371 out of 391, or 95%, of the D atoms of the protein and 58 solvent molecules. The IMAGINE instrument is designed to provide neutron data at or near atomic resolution (1.5 Å) from crystals with volume <1.0 mm3and with unit-cell edges <100 Å. Beamline features include novel elliptical focusing mirrors that deliver neutrons into a 2.0 × 3.2 mm focal spot at the sample position with full-width vertical and horizontal divergences of 0.5 and 0.6°, respectively. Variable short- and long-wavelength cutoff optics provide automated exchange between multiple-wavelength configurations (λmin= 2.0, 2.8, 3.3 Å to λmax= 3.0, 4.0, 4.5, ∼20 Å). These optics produce a more than 20-fold increase in the flux density at the sample and should help to enable more routine collection of high-resolution data from submillimetre-cubed crystals. Notably, the crystal used to collect thesePfRd data was 5–10 times smaller than those previously reported.
Drivers of snack foods impulse buying behaviour among young consumers
Authors: Duarte Paulo , Raposo Mário , Ferraz Marlene
Published: September 2013

Purpose

– This article aims to examine the influence of marketing-controlled external motivators of impulse buying behaviour of snack foods in cafeterias among young students.

Design/methodology/approach

– A questionnaire was used to ask a sample of 200 young consumers about their impulse buying behaviour in cafeterias. The resulting data were submitted to an in-depth four-stage quantitative analysis.

Findings

– The results show that there is not a unique profile of impulse buying behaviour and that young consumers can be effectively segmented in five groups according to their impulsive buying behaviour of snack foods using the eight factors revealed in the exploratory factor analysis. A new segment of health/nutrition-conscientious impulsive consumers was uncovered and characterized.

Research limitations/implications

– The major constraints of this study are the use of a non-probability convenience sampling design and sample size. Future studies should include other products and a more heterogeneous sample. The study represents a good starting point for further debate on impulsive buying behaviour.

Practical implications

– Most of the research done in this area has focused on the supermarket environment, neglecting other types of retail store. Companies could benefit from the current study as it provides them with information that can be used to improve their marketing strategies directed towards this specific market. Additionally, the findings can also help the development of public health policies better tailored to prevent overweight and obesity associated with snack food consumption.

Originality/value

– The study extends the current body of knowledge by examining the applicability and relevance of external motivators of impulse buying behaviour to a significantly different retail environment.
Evaluation of the horizontal electric field of the lightning channel with the fast convergent sommerfeld integral tail
Authors: Zou Jun , Zhou Chenglong , Li Wenwen , Lee Jae-bok , Chang Sughun
Published: September 2013

Purpose

– The electromagnetic field radiated from a lightning channel is the excitation for analyzing the field-to-transmission line coupling problem. The purpose of this paper is to propose a novel efficient approach to evaluate the horizontal electric field of the lightning channel expressed by the generalized Sommerfeld integral.

Design/methodology/approach

– The asymptotic integral is extracted from the original one, which actually makes the Sommerfeld integral tail reach its convergence very quickly. To handle the sharp variance around k0, a closed-form integral, which is obtained by replacing the original kernel with an approximated function, is presented in detail. The numerical examples validated the proposed approach in the both frequency and time domain.

Findings

– The approach proposed in this paper has been validated by the comparison with results in other papers. The agreement among these results reaches very well, and the approach proposed in this paper is more efficient and easy to implement, especially for the calculation of the tail integral part.

Originality/value

– In accordance with the numerical experiments, the proposed approach can be served as a qualified candidate in terms of computational efficiency to evaluate the electromagnetic field generated by the lightning channel.
Application of ON/OFF method to new conceptual design of magnetic devices
Authors: Takahashi Norio
Published: September 2013

Purpose

– The purpose of the paper is to show that how a new magnetic circuit, which the paper could not imagined beforehand, may be obtained using a newly developed ON/OFF topology optimization method by applying it to the design of magnetic head and motor.

Design/methodology/approach

– ON/OFF optimization technique combined with finite element method.

Findings

– It is shown that 3-D topology optimization of SPT head, in which the recording head is increased and the leakage flux is decreased, is possible using the proposed method. The optimization of IPM motor with the minimum torque ripple and the maximum toque is also examined.

Originality/value

– 3-D ON/OFF optimization method applied to practical problems considering the nonlinearity and rotation of rotor, etc.
A comparison between hybrid methods: FEM-BEM versus FEM-DBCI
Authors: Aiello Giovanni , Alfonzetti Salvatore , Borzì Giuseppe , Agatino Rizzo Santi , Salerno Nunzio
Published: September 2013

Purpose

– The purpose of this paper is to compare the hybrid FEM-BEM and FEM-DBCI methods for the solution of open-boundary static and quasi-static electromagnetic field problems.

Design/methodology/approach

– After a brief review of the two methods (both coupling a differential equation for the interior problem with an integral equation for the exterior one), they are compared in terms of accuracy, memory and computing time requirements by means of a set of simple examples.

Findings

– The comparison suggests that FEM-BEM is more accurate than FEM-DBCI but requires more computing time.

Practical implications

– Then FEM-DBCI appears more appropriate for applications which require a shorter computing time, for example in the stochastic optimization of electromagnetic devices. Conversely, FEM-BEM is more appropriate in cases in which a high level of precision is required in a single computation.

Originality/value

– Note that the FEM-BEM considered in this paper is a non standard one in which the nodes of the normal derivative on the truncation boundary are placed in positions different from those of the potential.
Dielectric-free multi-band frequency selective surface for antenna applications
Authors: Ramaccia Davide , Bilotti Filiberto , Toscano Alessandro , Vegni Lucio
Published: September 2013

Purpose

– The purpose of this paper is to design simple and high-performing screens capable to separate circularly polarized electromagnetic waves in Ku band from the ones in Ka band.

Design/methodology/approach

– The proposed screen consists of an inductive double resonant element FSS, i.e. a regular array of circular holes in a metal thick plate, in order to grant the robustness to mechanical stress for antenna applications in extreme conditions.

Findings

– The proposed design of a multi-band frequency selective surface (FSS) is able to separate circularly polarized electromagnetic waves in Ku band from the ones in Ka band.

Originality/value

– The paper shows the capabilities of a novel FSS that combine the transmission properties of two simple FSSs which allows us to achieve an interesting behaviour in three typical bands of the satellite communications.
Achieving PMC boundary conditions through metamaterials
Authors: Monti Alessio , Scorrano Luca , Tricarico Simone , Bilotti Filiberto , Toscano Alessandro , Vegni Lucio
Published: September 2013

Purpose

– The purpose of this paper is to show how metamaterials with extreme values of permittivity and permeability, may be effectively used to design artificial magnetic conductors (AMC) at a given frequency. In particular, this paper theoretically determines, for the different polarizations of the incidence field, the conditions under which metamaterials can behave as an AMC.

Design/methodology/approach

– In order to find out the required values of the constitutive parameters, this paper has done a theoretical analysis based on the transmission-line theory. The obtained analytical reflection coefficient has been particularized for the different possible polarizations of the incidence field in order to find the constitutive parameters values that this paper needs for the AMC behavior.

Findings

– Depending on the polarization of the field, it is shown that different values of the constitutive parameters are needed to get AMCs. In particular, it is shown that in the case of TEM and TE polarizations, a large value of the permeability is enough to obtain an AMC boundary condition. In the case of the TM polarization, instead, the AMC boundary condition is effectively achieved by using a material with vanishing permittivity. The role of the permittivity in the three polarizations is discussed. Finally, possible implementations and applications at microwave and optical frequencies are presented.

Originality/value

– The idea of using miniaturized inclusions to obtain AMCs is not completely new. However, to the authors' best knowledge, a complete and rigorous theoretical analysis showing the capabilities and the limits of this approach has not yet been presented in the open technical literature.
Finite element model of charge transport across ionic channels
Authors: Laudani Antonino , Coco Salvatore , Riganti Fulginei Francesco
Published: September 2013

Purpose

– The paper aims to illustrate the two kinds of analysis approach for which finite element method (FEM) can be successfully employed: the Poisson-Nernst-Planck (PNP) model and the Langevin-Lorentz-Poisson (LLP) one.

Design/methodology/approach

– The approach of this work is to try making a survey of the use of the FEM in the modelling of charge transport/ion flow across membrane channels, in particular for the PNP analysis and for a particle based model such as LLP model.

Findings

– In this paper, the two kinds of analysis approach for which FEM can be successfully employed, the PNP model and the LLP one, have been shown. In both cases the FEM is extremely useful to carry out these analysis and the simulation results obtained are in good agreement with experimental results.

Originality/value

– The value of this paper is to demonstrate the FEM is extremely useful to carry out analysis and results which are in good agreement with experimental ones.
Participation in decision making: a case study of job satisfaction and commitment (part three)
Authors: H. Appelbaum Steven , Louis Damien , Makarenko Dmitry , Saluja Jasleena , Meleshko Olga , Kulbashian Sevag
Published: September 2013

Purpose

– When employees believe in and trust their management, it motivates and encourages employees' participation in decision making which improves employees' efforts, benefits their job satisfaction and commitment to work. All of these factors, in turn, contribute to a trustworthy manager-employee relationship. While the literature supports this premise, there is little empirical evidence that patterns of causal inference in the relationship are clearly understood. This three-part empirical case seeks to focus on studying the relations between employee trust in management in a Quebec manufacturing company and their job satisfaction, intention to quit, level of employee participation in decision making and their commitment.

Design/methodology/approach

– This empirical case will test five hypotheses regarding seven variables influencing the level of employee engagement and commitment, employee turnover, employee participation in decision-making processes and job satisfaction.

Findings

– The article finds that employee trust in management is an important determinant of their willingness to participate in decision making. Insufficient employee participation in decision making in turn leads to low level of employee job satisfaction and employee commitment. Lack of employee commitment and engagement affects the employee's intention to quit.

Research limitations/implications

– The sample size of the office workers was not sufficient in order to have statistically significant results of the correlations between the variables for the production department employees and for the office/administrative staff. This could have helped to determine the level of internal communication specifically, but also the level of all of the other variables for the two different groups of employees.

Practical implications

– This article offers useful insights for management in relation to strengthening interpersonal trust within an organization, introducing employee empowerment practices and increasing employee job satisfaction and commitment.

Originality/value

– The findings provide empirical evidence to support theoretical models that link employee trust in management, participation in decision making, job satisfaction, commitment, and turnover intentions and highlight the impact of these factors on organizational performance.
Investigating the wellness tourism factors in hot spring hotel customer service
Authors: Chen Kaung-Hwa , Chang Feng-Hsiang , Wu (Kenny) Chihkang
Published: September 2013

Purpose

– This study aims to establish customer service factors for wellness tourism from both service providers and customer perspectives, and to determine whether gender and age factors affect older tourist opinions of customer service.

Design/methodology/approach

– The authors interviewed 13 experts in the hot spring hotel industry and more than 469 hot spring hotel visitors who are over 50 years of age. Content validity and homogeneity reliability as proposed by Aiken were used to confirm customer service factors. This study uses the verbal-linguistic evaluation to assess customer service factors and each service item associated with these factors.

Findings

– Eight crucial customer service factors, from high to low, are personnel services, environments, healthy diet, relaxation, health promotion treatments, experience of unique tourism resources, social activities, and mental learning.

Research limitations/implications

– This study implicated allocation and management of input resources as the service factors that are used for determining the preferences of older consumers in wellness tourism.

Originality/value

– Numerous countries are currently facing an aging population and market opportunities for wellness tourism are popular with the tourism industry. Studies show that enhanced customer service increases competitive advantage in the tourism industry. However, customer service differs from what customers prefer. For this study, the authors compiled the viewpoints of older consumers, hotel personnel, and expert opinions in the hotel industry to identify customer-service factors in wellness tourism. The analytical results of this study suggest that hot spring hotels in Taiwan can focus on critical customer-service items, resource management, and resource allocation.
Is the gaming industry still recession-proof?
Authors: Zheng Tianshu , Farrish John , Lee Ming-Lun , Yu Hui
Published: September 2013

Purpose

– The purpose of this study is to examine how the recent recession affected Iowa's gaming industry by analyzing gaming volumes before and through the recession.

Design/methodology/approach

– This study used autoregressive integrated moving average (ARIMA) with intervention analysis to examine Iowa statewide aggregated monthly slot coin-in, table drop, and admission from December 2001 through June 2012.

Findings

– The results of analyses show that: slot coin-in was not affected by the recession; table drop was slightly affected, but started to recover in late 2010; and monthly admission was not affected by the recession, and showed a significant increase after the recession. The results also indicate that the decrease in table drop in Iowa casinos represented only a very small amount of state gaming revenue in 2008. Therefore, the findings of this study suggest that Iowa's gaming volume was not significantly affected by the recent recession. In other words, Iowa's gaming industry is still recession-proof.

Practical implications

– Current economic conditions suggest that the threat of a double-dip recession is quite real. The findings of this study are expected to help casino managers in Iowa understand how non-destination casinos behaved differently through the recession and strategically plan for a possible future economic downturn. In fact, the significant increase of monthly admission during the last recession implies that the Iowa gaming industry has actually benefited from the recession by accommodating more patrons. Therefore, to capitalize on the next recession, Iowa's casino operators should consider reducing the number of table games and increasing the number of slot machines to accommodate more slot players and reduce operating costs.

Originality/value

– Most existing gaming-related research focuses on gaming destinations such as Las Vegas and Atlantic City. No known study on gaming volume in non-destination gaming markets has been identified. By examining Iowa's gaming volume through the recession, this study provides initial empirical evidence of the impact of recession on non-destination gaming markets.
Truth or consequences
Authors: Fleck Denise , Volkema Roger , Levy Barbara , Pereira Sergio , Vaccari Lara
Published: September 2013

Purpose

– This paper aims to describe a study of the negotiation process, focusing on the use of seven competitive-unethical tactics in dyadic negotiations. The initial use of these tactics and their effects on process and outcomes are examined.

Design/methodology/approach

– In total, 230 Brazilian professionals from a large financial institution participated in two-party, property-leasing negotiations involving eight issues with assigned point values. Negotiations were conducted online and, from the recorded transcripts, seven competitive-unethical tactics were tracked and analyzed with respect to the negotiation process and outcomes (individual and joint, perceived and actual).

Findings

– The study found that most participants employed one or more tactics, the stage and incidents of initial use affected overall employment, and participants often reciprocated when tactics were employed. Reciprocation was best described by a logarithmic function, with a small number of tactics answered with as many or more tactics, but a large number of tactics producing a smaller response. Also, number of messages exchanged and number of tactics per message were related to likelihood of reaching an agreement and, to some extent, to individual outcomes (actual and perceived). Reaching an agreement and perceived individual outcome were associated with a participant's desire to negotiate with a counterpart in the future.

Originality/value

– The vast majority of studies to date have employed questionnaires to measure ethical attitudes or intentions, or have limited their empirical studies to competitive tactics only. This study moves beyond these methodologies to examine the actual use of a range of competitive-unethical tactics, and their effects on process and outcomes.
Significant Incident Learning Process (SILP) – the experience of facilitating and evaluating the process in adult safeguarding
Authors: Clawson Rachael , Kitson Deborah
Published: September 2013

Purpose

– In recent years a variety of methods have been used to review cases where a vulnerable adult has died or been seriously harmed, the method chosen largely depending upon whether a single agency or multi-agency approach is required. Serious Case Reviews (SCRs) are more frequently used in cases requiring a multi-agency approach; however, their effectiveness in terms of being timely, value for money and a means of learning lessons has been questioned. Safeguarding Adult Boards (SAB) in the East Midlands have sought alternative means for reviewing some cases including the Significant Incident Learning Process (SILP). The purpose of this paper is to explore the experience of facilitating and evaluating a pilot SILP.

Design/methodology/approach

– The paper explores the purpose and function of the SILP and then examines the process of facilitating a “live” event. A range of issues are explored including who should be involved, concerns around participation and working alongside criminal/police investigations and/or therapeutic intervention.

Findings

– The findings are discussed and highlight the need for skilled, independent facilitators and robust “ground rules”. The paper evaluates the process and makes recommendations for further use of SILP.

Originality/value

– This paper explores a new approach to reviewing cases previously reviewed using SCR, as such it will be of interest to all agencies and organisations represented on SAB. The evaluation of the SILP found it to be favourable in comparison with SCRs in terms of cost, being a process that can be completed within three months of an incident occurring and in terms of timely dissemination of lessons learned.
Stairways to heaven: implementing social media in organizations
Authors: Levy Moria
Published: September 2013

Purpose

– This paper is aimed at both researchers and organizations. For researchers, it seeks to provide a means for better analyzing the phenomenon of social media implementation in organizations as a knowledge management (KM) enabler. For organizations, it seeks to suggest a step-by-step architecture for practically implementing social media and benefiting from it in terms of KM.

Design/methodology/approach

– The research is an empirical study. A hypothesis was set; empirical evidence was collected (from 34 organizations). The data were analyzed both quantitatively and qualitatively, thereby forming the basis for the proposed architecture.

Findings

– Implementing social media in organizations is more than a yes/no question; findings show various levels of implementation in organizations: some implementing at all levels, while others implement only tools, functional components, or even only visibility.

Research limitations/implications

– Two main themes should be further tested: whether the suggested architecture actually yields faster/eased KM implementation compared to other techniques; and whether it can serve needs beyond the original scope (KM, Israel) as tested in this study (i.e. also for other regions and other needs – service, marketing and sales, etc.).

Practical implications

– Organizations can use the suggested four levels architecture as a guideline for implementing social media as part of their KM efforts.

Originality/value

– This paper is original and innovative. Previous studies describe the implementation of social media in terms of yes/no; this research explores the issue as a graded one, where organizations can and do implement social media step-by-step. The paper's value is twofold: it can serve as a foundational study for future researches, which can base their analysis on the suggested architecture of four levels of implementation. It also serves as applied research that will help organizations searching for social media implementation KM enablers.
Visualisation of the organisation knowledge structure evolution
Authors: Štorga Mario , Mostashari Ali , Stanković Tino
Published: September 2013

Purpose

– The paper aims to provide a methodology by which organisational knowledge can be extracted and visualised dynamically over time, providing a glimpse into the knowledge evolution processes that occur within organisations.

Design/methodology/approach

– Recursive analysis of email interactions is offered as a case to account for the knowledge structure evolution related to the different programs of international non-governmental organization (INGO). Several methods are used: analysis of the network expansion to see whether the process is random or uniform is performed, visualisation of the network configuration changes throughout studied time period; and the statistical examination of network formation.

Findings

– The results of the presented study indicate that content structure of electronic knowledge networks exhibits hierarchical and centralised tendencies. The social network analysis results suggest that INGO exhibits non-hierarchical and decentralized structure of the individuals contributing to the discussion lists.

Research limitations/implications

– By providing the means to carry out network evolution analysis of content structure dynamics and social interactions, the presented work provides a means for probabilistically modelling patterns of organisational knowledge evolution.

Practical implications

– The approach allows the exploration of the dynamics of tacit to explicit knowledge, from individual to the group and from informal groups to the whole organisation.

Originality/value

– By displaying the large collection of the key phrases that reflected the evolution of the organisational knowledge structure over the time, organisational emails are placed in meaningful context explaining the language of the organisation and context of knowledge structure evolution.