bluuebunny/crossref_metadata_2025 huggingface dataset:
Shape memory behaviour of HA-g-PDLLA nanocomposites prepared via in situ polymerization
Authors: Du Ke , Gan Zhihua
Published: March 2014

HA nanoparticles grafted in a PDLLA matrix play an important role for HA-g-PDLLA nanocomposites with excellent shape memory properties.
Phage-based detection of bacterial pathogens
Authors: van der Merwe R. G. , van Helden P. D. , Warren R. M. , Sampson S. L. , Gey van Pittius N. C.
Published: March 2014

Bacterial pathogens cause significant morbidity and mortality annually to both humans and animals. With the spread of drug resistance and the diminishing effectiveness of antibiotics, there is a pressing need for effective diagnostics for detection of bacterial pathogens. Bacteriophages offer several unique opportunities for bacterial detection. This review highlights the means by which bacteriophages have been utilized to achieve and facilitate specific bacterial detection.
Determination of propranolol and hydrochlorothiazide by batch injection analysis with amperometric detection and capillary electrophoresis with capacitively coupled contactless conductivity detection
Authors: Gimenes Denise Tofanello , Marra Mariana Cardoso , Abarza Muñoz Rodrigo Alejandro , Angnes Lúcio , Richter Eduardo Mathias
Published: March 2014

Two new and fast electrochemical methods for separation and determination of propranolol and hydrochlorothiazide.
Electrochemical modulation of SERS at the liquid/liquid interface
Authors: Booth Samuel G. , Cowcher David P. , Goodacre Royston , Dryfe Robert A. W.
Published: March 2014

The potential applied to an oil–water interface is used to modulate the SERS response in the presence of adsorbed Ag nanoparticles.
The sodium ion-assisted memory behaviour of a silicon nanowire partial composite field-effect transistor
Authors: Moon Kyeong-Ju , Lee Tae Il , Lee Sang-Hoon , Myoung Jae-Min
Published: March 2014

A partial composite consisting of rough silicon nanowires and a polymer dielectric layer with sufficient Na+ ions was used to create a field-effect transistor based memory device.
Epitaxial growth of YBa2Cu3O7−x films on Ce0.9La0.1O2−y buffered yttria-stabilized zirconia substrates by an all-chemical-solution route
Authors: Zhao Yue , Wu Wei , Tang Xiao , Andersen Niels Hessel , Han Zhenghe , Grivel Jean-Claude
Published: March 2014

A high critical current density of 3 MA cm−2 (77 K, self-field) was achieved on a YBa2Cu3O7 film deposited on Ce0.9La0.1O2 buffered yttria-stabilized zirconia substrate, which is an all-chemical derived configuration.
Pt nanoparticles supported on Sb-doped SnO2 porous structures: developments and issues
Authors: Fabbri E. , Rabis A. , Kötz R. , Schmidt T. J.
Published: March 2014

Control of the metal oxide surface properties leads in the case of Sb–SnO2 to a support material for Pt nanoparticles with tailored catalyst corrosion stability and activity.
Terpyridine complexes of first row transition metals and electrochemical reduction of CO2 to CO
Authors: Elgrishi Noémie , Chambers Matthew B. , Artero Vincent , Fontecave Marc
Published: March 2014

Homoleptic terpyridine complexes of 3d transition metals are found to electrocatalytically reduce CO2 to either CO or tuneable CO–H2 mixtures.
Beyond the volcano limitations in electrocatalysis – oxygen evolution reaction
Authors: Halck Niels Bendtsen , Petrykin Valery , Krtil Petr , Rossmeisl Jan
Published: March 2014

Oxygen evolution catalysis is restricted by the interdependence of adsorption energies of the reaction intermediates and the surface reactivity.
A highly efficient and recyclable Fe3O4 magnetic nanoparticle immobilized palladium catalyst for the direct C-2 arylation of indoles with arylboronic acids
Authors: Zhang Lei , Li Pinhua , Liu Can , Yang Jin , Wang Min , Wang Lei
Published: March 2014

An efficient and reusable Fe3O4-nanoparticle-immobilized-palladium catalyst was prepared and applied to the direct C-2 arylation of indoles with arylboronic acids.
Water oxidation catalysts and pH sensors based on azo-conjugated iridium/rhodium motifs
Authors: Yu Wei-Bin , He Qing-Ya , Shi Hua-Tian , Pan Yan , Wei Xianwen
Published: March 2014

Ionic half-sandwich Ir(iii) and Rh(iii) fragments coordinated by azo compounds exhibit good electrochemical properties, therefore, they can be employed as catalysts in water oxidation. The color of aqueous solutions of these complexes changes from brown to green at pH 12, so they can be used as pH sensors.
Dissolution and regeneration of wool keratin in ionic liquids
Authors: Idris Azila , Vijayaraghavan R. , Rana Usman Ali , Patti A. F. , MacFarlane D. R.
Published: March 2014

Substantial dissolution of wool was obtained in [AMIM][dca] and [choline][thioglycolate] ionic liquids as well as in deep eutectic solvent mixtures, under a variety of conditions including the use of a reducing agent.
Engineering electronic properties of layered transition-metal dichalcogenide compounds through alloying
Authors: Kutana Alex , Penev Evgeni S. , Yakobson Boris I.
Published: March 2014

We report thermodynamic and electronic properties of 2D transition metal dichalcogenide alloys beyond the mean field approximation.
γ-Fe2O3–MWNT/poly(p-phenylenebenzobisoxazole) composites with excellent microwave absorption performance and thermal stability
Authors: Chen Yi , Liu Xiaoyun , Mao Xiaoyang , Zhuang Qixin , Xie Zhong , Han Zhewen
Published: March 2014

A thermostable γ-Fe2O3–MWNTs/PBO composite with excellent absorption properties was obtained with a low content of magnetic fillers and a well defined structure.
Creation of nanopores on graphene planes with MgO template for preparing high-performance supercapacitor electrodes
Authors: Wang Huanjing , Sun Xiuxia , Liu Zonghuai , Lei Zhibin
Published: March 2014

Creation of nanopores on a graphene basal plane is particularly significant to improve its rate-performance and utilization efficiency in a supercapacitor electrode.
Multivalency in healable supramolecular polymers: the effect of supramolecular cross-link density on the mechanical properties and healing of non-covalent polymer networks
Authors: Hart Lewis R. , Hunter James H. , Nguyen Ngoc A. , Harries Josephine L. , Greenland Barnaby W. , Mackay Michael E. , Colquhoun Howard M. , Hayes Wayne
Published: March 2014

Mechanical properties of healable supramolecular polymer blends correlate to non-covalent “crosslink density”.
Ruthenium/Yb(OTf)3-cocatalyzed dehydrogenative synthesis of 14-substituted-14-H-dibenzo[a,j]xanthenes from β-naphthol and alcohols
Authors: Wang Xiaoting , Chen Mengmeng , Xie Feng , Zhang Min
Published: March 2014

An efficient ruthenium/Yb(OTf)3-cocatalyzed dehydrogenative synthesis of 14-substituted-14-H-dibenzo[a,j]xanthenes from β-naphthol and alcohols has been demonstrated.
Simple and highly efficient direct thiolation of the surface of carbon nanotubes
Authors: Hsu Ming-Hua , Chuang Hong , Cheng Fong-Yu , Huang Ying-Pei , Han Chien-Chung , Pao Kuan-Chuan , Chou Shih-Ching , Shieh Fa-Kuen , Tsai Fu-Yuan , Lin Chung-Chang , Wu Dian-Syue , Chang Chia-Ching
Published: March 2014

We proposed a simple and high efficiency method for direct thiolation on the surface of the carbon nanotubes.
Colorimetric and near infrared fluorescent detection of cyanide by a new phenanthroimidazole–indolium conjugated probe
Authors: Zhang Yi , Yu Dehuan , Feng Guoqiang
Published: March 2014

A new dual colorimetric and fluorescent probe was developed for rapid detection of cyanide anions with high selectivity and sensitivity.
MnO2nano/micro hybrids for supercapacitors: “Nano's Envy, Micro's pride”
Authors: Roshny S. , Ranjusha R. , Deepak M. S. , Sanoj Rejinold N. , Jayakumar R. , Nair S. V. , Balakrishnan A.
Published: March 2014

The present study provides the first reports on a low temperature molten salt route which can generate unique architecture of MnO2nanospikes arrayed in a peculiar fashion to form micron sized ball morphology.
An approach towards the synthesis and characterization of ZnO@Ag core@shell nanoparticles in water-in-oil microemulsion
Authors: Satter Shazia Sharmin , Hoque Mahfuzul , Rahman M. Muhibur , Mollah M. Yousuf A. , Bin Hasan Susan Md. Abu
Published: March 2014

Water-in-oil microemulsions have been found to be good templates for synthesis of ZnO and ZnO@Ag nanoparticles and offered themselves as ideal ‘nanoreactors’ for uniform fabrication of core@shell nanoparticles.
A catalase-magnetic switch for cell proliferation
Authors: Municoy Sofia , Ibañez Irene L. , Durán Hebe , Bellino Martín G.
Published: March 2014

The combination of enzymes to tackle cell messengers with magnetite nanoparticles was exploited to control cell behavior by means of magnetic fields.
Evolutionary numerical simulation approach for design optimization of gas turbine blade cooling channels
Authors: Nagaiah Narasimha R. , Geiger Christopher D.
Published: March 2014

Gas turbine blade cooling system design is a multidisciplinary, iterative and often tedious task involving complex relationships among multiple design objectives. Typical blade design requires a broad range of expertise in the materials, structural, heat transfer, and cost optimization disciplines. The multiple objectives involved are often conflicting and must be solved simultaneously with equal importance. The traditional approaches researchers scalarize the multiple objectives into a single objective using a weight vector, thus transforming the original multiple objective problem into a single objective problem. This research addresses the shortcomings of existing traditional approaches of the optimization of blade cooling configuration design.
Opinion formation on social media: An empirical approach
Authors: Xiong Fei , Liu Yun
Published: March 2014

Opinion exchange models aim to describe the process of public opinion formation, seeking to uncover the intrinsic mechanism in social systems; however, the model results are seldom empirically justified using large-scale actual data. Online social media provide an abundance of data on opinion interaction, but the question of whether opinion models are suitable for characterizing opinion formation on social media still requires exploration. We collect a large amount of user interaction information from an actual social network, i.e., Twitter, and analyze the dynamic sentiments of users about different topics to investigate realistic opinion evolution. We find two nontrivial results from these data. First, public opinion often evolves to an ordered state in which one opinion predominates, but not to complete consensus. Second, agents are reluctant to change their opinions, and the distribution of the number of individual opinion changes follows a power law. Then, we suggest a model in which agents take external actions to express their internal opinions according to their activity. Conversely, individual actions can influence the activity and opinions of neighbors. The probability that an agent changes its opinion depends nonlinearly on the fraction of opponents who have taken an action. Simulation results show user action patterns and the evolution of public opinion in the model coincide with the empirical data. For different nonlinear parameters, the system may approach different regimes. A large decay in individual activity slows down the dynamics, but causes more ordering in the system.
On lower bounds for possible blow-up solutions to the periodic Navier-Stokes equation
Authors: Cortissoz Jean C. , Montero Julio A. , Pinilla Carlos E.
Published: March 2014

We show a new lower bound on the $\dot{H}^{\frac{3}{2}}\left(\mathbb {T}^3\right)$Ḣ32T3 norm of a possible blow-up solution to the Navier-Stokes equation, and also comment on the extension of this result to the whole space. This estimate can be seen as a natural limiting result for Leray's blow-up estimates in $L^p\left(\mathbb {R}^3\right)$LpR3, 3 < p < ∞. We also show a lower bound on the blow-up rate of a possible blow-up solution of the Navier-Stokes equation in $\dot{H}^{\frac{5}{2}}\left(\mathbb {T}^3\right)$Ḣ52T3, and give the corresponding extension to the case of the whole space.
On a regularization of a scalar conservation law with discontinuous coefficients
Authors: Shen Chun
Published: March 2014

This paper is devoted to a scalar conservation law with a linear flux function involving discontinuous coefficients. It is clear that the delta standing wave should be introduced into the Riemann solution in some nonclassical situation. In order to study the formation of delta standing wave, we consider a regularization of the discontinuous coefficient with the Helmholtz mollifier and then obtain a regularized system which depends on a regularization parameter ɛ > 0. The regularization mechanism is a nonlinear bending of characteristic curves that prevents their finite-time intersection. It is proved rigorously that the solutions of regularized system converge to the delta standing wave solution in the ɛ → 0 limit. Compared with the classical method of vanishing viscosity, here it is clear to see how the delta standing wave forms naturally along the characteristics.
Stability of multiferroicity against Dy/Mn off-stoichiometry in DyMnO3
Authors: Wang J. X. , Liu M. F. , Zhao Z. Y. , Yan Z. B. , Liu J.-M.
Published: March 2014

We investigate the effects of slight Dy/Mn off-stoichiometry on the multiferroic behaviors of DyMnO3 (Dy1−xMn1+xO3). It is revealed that the distorted lattice structure and ferroelectric property exhibit higher stability against the Mn deficiency than the Dy deficiency. Since the electric polarization includes the contributions from the Mn-Mn and Dy-Mn interactions, the measured polarization exhibits different dependence on the Mn deficiency from that on the Dy deficiency. The present work suggests that the Dy/Mn off-stoichiometry is detrimental to the ferroelectricity, owing to the modulated spin interactions and reshuffled spin frustration.
Phase evaluation, magnetic, and electric properties of Mn60+xGa40−x (x = 0–15) ribbons
Authors: Feng J. N. , Zhao X. G. , Ning X. K. , Shih C. W. , Chang W. C. , Ma S. , Liu W. , Zhang Z. D.
Published: March 2014

Mn60+xGa40−x (x = 0, 5, 10, and 15) ribbons were prepared by the melt-spinning technique and subsequently by a heat treatment at 673 K for 1 h. The magnetic phases Mn8Ga5, Mn1.86Ga, D019-Mn3Ga, and D022-Mn3Ga are found to appear in these annealed melt-spun ribbons. The Curie temperature TC of the ribbons varies from 125 K to 185 K as x changes from 0 to 5. For x = 10, the hexagonal structure of the D019-Mn3Ga phase is distorted to an orthorhombic one below the phase transition temperature Td = 185 K. The optimized values for coercivity at room temperature are 0.13, 4.4, 8.1, and 7.7 kOe for the ribbons with x = 0, 5, 10, and 15, respectively. The resistance measurements indicate that the ribbons show a typical metallic behavior for x = 5–15.
Note: A fast pneumatic sample-shuttle with attenuated shocks
Authors: Biancalana Valerio , Dancheva Yordanka , Stiaccini Leonardo
Published: March 2014

We describe a home-built pneumatic shuttle suitable for the fast displacement of samples in the vicinity of a highly sensitive atomic magnetometer. The samples are magnetized at 1 T using a Halbach assembly of magnets. The device enables the remote detection of free-induction-decay in ultra-low-field and zero-field nuclear magnetic resonance (NMR) experiments, in relaxometric measurements and in other applications involving the displacement of magnetized samples within time intervals as short as a few tens of milliseconds. Other possible applications of fast sample shuttling exist in radiological studies, where samples have to be irradiated and then analyzed in a cold environment.
Influence of Penning effect on the plasma features in a non-equilibrium atmospheric pressure plasma jet
Authors: Chang Zhengshi , Jiang Nan , Zhang Guanjun , Cao Zexian
Published: March 2014

Non-equilibrium atmospheric pressure plasma jet (APPJ) is a cold plasma source that promises various innovative applications. The influence of Penning effect on the formation, propagation, and other physical properties of the plasma bullets in APPJ remains a debatable topic. By using a 10 cm wide active electrode and a frequency of applied voltage down to 0.5 Hz, the Penning effect caused by preceding discharges can be excluded. It was found that the Penning effect originating in a preceding discharge helps build a conductive channel in the gas flow and provide seed electrons, thus the discharge can be maintained at a low voltage which in turn leads to a smaller propagation speed for the plasma bullet. Photographs from an intensified charge coupled device reveal that the annular structure of the plasma plume for He is irrelevant to the Penning ionization process arising from preceding discharges. By adding NH3 into Ar to introduce Penning effect, the originally filamentous discharge of Ar can display a rather extensive plasma plume in ambient as He. These results are helpful for the understanding of the behaviors of non-equilibrium APPJs generated under distinct conditions and for the design of plasma jet features, especially the spatial distribution and propagation speed, which are essential for application.
On the nature of kinetic electrostatic electron nonlinear (KEEN) waves
Authors: Dodin I. Y. , Fisch N. J.
Published: March 2014

An analytical theory is proposed for the kinetic electrostatic electron nonlinear (KEEN) waves originally found in simulations by Afeyan et al. [arXiv:1210.8105]. We suggest that KEEN waves represent saturated states of the negative mass instability (NMI) reported recently by Dodin et al. [Phys. Rev. Lett. 110, 215006 (2013)]. Due to the NMI, trapped electrons form macroparticles that produce field oscillations at harmonics of the bounce frequency. At large enough amplitudes, these harmonics can phase-lock to the main wave and form stable nonlinear dissipationless structures that are nonstationary but otherwise similar to Bernstein-Greene-Kruskal modes. The theory explains why the formation of KEEN modes is sensitive to the excitation scenario and yields estimates that agree with the numerical results of Afeyan et al. A new type of KEEN wave may be possible at even larger amplitudes of the driving field than those used in simulations so far.
One-dimensional zinc ferrite nano-chains synthesis by chemical self-assembly assistant by magnetic field
Authors: Kou Zhaoxia , Zhang Wen , Wang Yukun , Johnny Wong Ping Kwan , Huang Haibo , Ji Cheng , Yue Jinjin , Zhang Dong , Zhai Ya , Zhai Hongru
Published: March 2014

A series of zinc ferrite chains have been synthesized successfully by using the self-assembly method in different synthesizing magnetic fields. The particle chains are arranged in order on the Si substrate under the assistant magnetic field. The zinc ferrite chains show various length-to-radius aspect ratio, saturation magnetization Ms, remanent magnetization Mr, and coercivity Hc in the corresponding synthesizing magnetic fields. Using X-ray magnetic circular dichroism, the Zn substitution mechanism in the ferrite chains has been analyzed and discussed.
Simulation of diffusiophoresis force and the confinement effect of Janus particles with the continuum method
Authors: Wu Meiling , Zhang Hongyan , Zheng Xu , Cui Haihang
Published: March 2014

The Janus particle is a special class of colloidal particle that has different surface characteristics on its two hemispheres. In the microsystem field, an interesting application is the Janus particle's self-propulsion. Diffusiophoresis (DFP) provides one possible mechanism to explain this phenomenon. In this paper, we used the continuum model to simulate DFP and to study the confinement effect of Janus particles travelling on the substrate. In the experiment, we noticed a special quasi-1D motion, in which the DFP force is dominant and particles move at a constant velocity within a short interval approximately along a straight line. This enables us to adopt a reference frame to numerically study the distributions of the flow field and concentration field and hence to evaluate the different forces. Because the confinement effect has a great influence on the magnitude of forces, the gaps were calculated accurately according to the force balance principle. Meanwhile, the fitting coefficients to match the experimental and numerical results were suggested. This result may help us to get a better understanding of self-propulsion and is also beneficial for designing a DFP-based micro-device.
The effect of the host composition on the lifetime decay properties of barium/strontium aluminates compounds
Authors: Rezende Marcos V. dos S. , Andrade A. B. , Valerio Mário E. G. , Montes Paulo J. R
Published: March 2014

This paper reports the influence of the structural change on the luminescence of Eu-doped barium/strontium aluminates when excited with monochromatic X-rays (also known as X-ray excited optical luminescence—XEOL). Ba1−xSrxAl2O4 samples, with 0 < x < 1, were produced via proteic sol-gel route and it was observed that the XEOL emission spectra are composed by the Eu2+ and Eu3+ transitions, although no Eu2+ was observed in the X-ray absorption spectra. The XEOL intensities while the sample is under irradiation decreased as a function of the irradiation time, indicating the buildup of radiation damage. The saturation level of the XEOL is directly correlated to the amount of damages induced by the irradiation and the sample composition. The Ba-rich samples are the ones with higher XEOL yield. X-ray induced long lasting phosphorescence (LLP) was also observed for all samples and it was found that the duration of the phosphorescence emission also depends on the sample composition. In Sr-rich samples, the LLP has a slower decay time constant than in Ba-rich samples. A model of the radiation induced luminescence is presented and all these features are discussed in terms of the energetic costs and the type of defects generated in the sample.
The Possible Experts: How Epistemic Communities Negotiate Barriers to Knowledge Use in Ecosystems Services Policy
Authors: Dunlop Claire A
Published: March 2014

The increased salience of how to value ecosystems services has driven up the demand for policy-relevant knowledge. It is clear that advice by epistemic communities can show up in policy outcomes, yet little systematic analysis exists prescribing how this can actually be achieved. This paper draws on four decades of knowledge utilisation research to propose four types of ‘possible expert’ who might be influential on ecosystems services. Broad findings of a literature review on knowledge use in public policy are reported, and the four-fold conceptualisation pioneered by Carol Weiss that defines the literature is outlined. The field is then systematised by placing these four modes of knowledge use within an explanatory typology of policy learning. With how, when, and why experts and their knowledge are likely to show up in policy outcomes established, the paper then proposes the boundaries of the possible in how the ecosystems services epistemic community might navigate the challenges associated with each learning mode. Four possible experts emerge: with political antenna and epistemic humility; with the ability to speak locally and early to the hearts and minds of citizens; with a willingness to advocate policy; and, finally, with an enhanced institutional awareness and peripheral policy vision. The paper concludes with a brief discussion of the utility of the analysis.
Expectations and Experiences of Diverse Forms of Knowledge Use: The Case of the UK National Ecosystem Assessment
Authors: Waylen Kerry A , Young Juliette
Published: March 2014

Assessments of environmental issues are often expected to tackle the perceived disconnect between scientific knowledge and environmental policy making. However, their actual influence on processes of knowledge communication and use remains understudied. We provide one of the first studies of the UK National Ecosystem Assessment (NEA), itself one of the first national-level assessments of ecosystem services. We explore expectations, early experiences, and implications for its role in promoting knowledge use, drawing on both documentary evidence and qualitative analysis of interviews with NEA authors and potential users. Many interviewees expected instrumental use; that is, facts directly assisting problem solving. This matches the rhetoric surrounding the NEA's creation. However, we found more early evidence of interacting conceptual uses (learning), and strategic uses (sometimes deemed misuse). Such uses depend not only on assessment outputs, such as reports, but also on the processes of communication and interaction by which these are created. Thus, planning and analysis of such assessments should deemphasise instrumental use and instead focus on the complex knowledge ‘coproduction’ processes by which diverse and interacting forms of knowledge use may be realised.
Water diffusion reveals networks that modulate multiregional morphological plasticity after repetitive brain stimulation
Authors: Abe Mitsunari , Fukuyama Hidenao , Mima Tatsuya
Published: March 2014

Significance

Repetitive brain stimulation is an established experimental protocol that induces plasticity in the stimulated site. Recent evidence indicates additional plasticity-related changes in remote nonstimulated regions. However, the neural substrates underlying the remote effects are unknown. Diffusion-weighted MRI (DWI) probes water diffusion and can be used to estimate morphological changes in cortical tissue that occur with the induction of plasticity. We used DWI to evaluate morphological changes induced by repetitive brain stimulation in human brains. Our results reveal that synchronized fluctuations in the morphology of microstructures between stimulated and remote regions might form identify networks that allow retention of plasticity-related morphological changes in remote regions. These results increase our understanding of the effects of stimulation-induced plasticity on multiple brain regions.
Crenolanib is a selective type I pan-FLT3 inhibitor
Authors: Smith Catherine Choy , Lasater Elisabeth A. , Lin Kimberly C. , Wang Qi , McCreery Melissa Quino , Stewart Whitney K. , Damon Lauren E. , Perl Alexander E. , Jeschke Grace R. , Sugita Mayumi , Carroll Martin , Kogan Scott C. , Kuriyan John , Shah Neil P.
Published: March 2014

Significance

Rapid evolution of drug resistance associated with secondary kinase domain (KD) mutations is the best characterized mechanism of acquired resistance to effective tyrosine kinase inhibitor (TKI) therapy. Medicinal chemistry efforts have largely been devoted toward synthesizing type II TKIs that, by targeting an inactive kinase conformation, are believed to afford greater selectivity than type I TKIs that bind an active kinase conformation. The only previously described TKI with the ability to successfully suppress all resistance-conferring KD mutants (i.e. “pan-kinase” inhibitor) is the type II multikinase TKI ponatinib. Here, we demonstrate that a type I TKI can be potent, selective, and invulnerable to resistance-conferring KD mutation as a mechanism of resistance. Efforts to develop potent, selective type I pan-kinase inhibitors are warranted.
Leader cell positioning drives wound-directed collective migration in TGFβ-stimulated epithelial sheets
Authors: Chapnick Douglas A. , Liu Xuedong
Published: March 2014

During wound healing and cancer metastasis, cells are frequently observed to migrate in collective groups. This mode of migration relies on the cooperative guidance of leader and follower cells throughout the collective group. The upstream determinants and molecular mechanisms behind such cellular guidance remain poorly understood. We use live-cell imaging to track the behavior of epithelial sheets of keratinocytes in response to transforming growth factor β (TGFβ), which stimulates collective migration primarily through extracellular regulated kinase 1/2 (Erk1/2) activation. TGFβ-treated sheets display a spatial pattern of Erk1/2 activation in which the highest levels of Erk1/2 activity are concentrated toward the leading edge of a sheet. We show that Erk1/2 activity is modulated by cellular density and that this functional relationship drives the formation of patterns of Erk1/2 activity throughout sheets. In addition, we determine that a spatially constrained pattern of Erk1/2 activity results in collective migration that is primarily wound directed. Conversely, global elevation of Erk1/2 throughout sheets leads to stochastically directed collective migration throughout sheets. Our study highlights how the spatial patterning of leader cells (cells with elevated Erk1/2 activity) can influence the guidance of a collective group of cells during wound healing.
New Type IV Pili–Related Genes Involved in Early Stages of Ralstonia solanacearum Potato Infection
Authors: Siri María Inés , Sanabria Analía , Boucher Christian , Pianzzola María Julia
Published: March 2014

This study provides insights into the pathogenesis of Ralstonia solanacearum, in particular with regards to strains belonging to phylotype IIB, sequevar 1 (IIB-1) and their interaction with potato, its natural host. We performed a comparative genomic analysis among IIB-1 R. solanacearum strains with different levels of virulence in order to identify candidate virulence genes. With this approach, we identified a 33.7-kb deletion in a strain showing reduced virulence on potato. This region contains a cluster of six genes putatively involved in type IV pili (Tfp) biogenesis. Functional analysis suggests that these proteins contribute to several Tfp-related functions such as twitching motility and biofilm formation. In addition, this genetic cluster was found to contribute to early bacterial wilt pathogenesis and colonization fitness of potato roots.
Temporal Progression of ‘Candidatus Liberibacter asiaticus’ Infection in Citrus and Acquisition Efficiency by Diaphorina citri
Authors: Coletta-Filho Helvecio D. , Daugherty Matthew P. , Ferreira Cléderson , Lopes João R. S.
Published: March 2014

Over the last decade, the plant disease huanglongbing (HLB) has emerged as a primary threat to citrus production worldwide. HLB is associated with infection by phloem-limited bacteria (‘Candidatus Liberibacter’ spp.) that are transmitted by the Asian citrus psyllid, Diaphorina citri. Transmission efficiency varies with vector-related aspects (e.g., developmental stage and feeding periods) but there is no information on the effects of host–pathogen interactions. Here, acquisition efficiency of ‘Candidatus Liberibacter asiaticus’ by D. citri was evaluated in relation to temporal progression of infection and pathogen titer in citrus. We graft inoculated sweet orange trees with ‘Ca. L. asiaticus’; then, at different times after inoculation, we inspected plants for HLB symptoms, measured bacterial infection levels (i.e., titer or concentration) in plants, and measured acquisition by psyllid adults that were confined on the trees. Plant infection levels increased rapidly over time, saturating at uniformly high levels (≈108 copy number of 16S ribosomal DNA/g of plant tissue) near 200 days after inoculation—the same time at which all infected trees first showed disease symptoms. Pathogen acquisition by vectors was positively associated with plant infection level and time since inoculation, with acquisition occurring as early as the first measurement, at 60 days after inoculation. These results suggest that there is ample potential for psyllids to acquire the pathogen from trees during the asymptomatic phase of infection. If so, this could limit the effectiveness of tree rouging as a disease management tool and would likely explain the rapid spread observed for this disease in the field.
Is It Necessary to Assess for Fat‐Soluble Vitamin Deficiencies in Pediatric Patients With Newly Diagnosed Celiac Disease?
Authors: Imam Mohamad H. , Ghazzawi Yousef , Murray Joseph A. , Absah Imad
Published: March 2014

Background:

The purpose of this study was to identify the frequency of fat‐soluble vitamin deficiencies in children with celiac disease (CD) and to determine the value of routine testing for these deficiencies.

Methods:

We conducted a retrospective medical record review of patients with a confirmed diagnosis of CD and fat‐soluble vitamin levels measured at diagnosis between 1995 and 2012 at Mayo Clinic. Patients' demographics, fat‐soluble vitamin levels, and pertinent clinical factors at the time of diagnosis were collected.

Results:

Eighty‐three patients were included in the final analysis: 51 girls and 32 boys, with an average age at diagnosis of 12.8 years in girls and 13.0 years in boys. The most commonly reported symptoms were abdominal pain in 49 patients and diarrhea in 30 patients. Family history of CD was reported in 32 patients. Average vitamin levels for vitamin E, 25‐hydroxyvitamin D (25 (OH) D), and vitamin A were 7.5 mg/L, 32.8 ng/mL, and 334.5 μg/dL, respectively. No patients had vitamin A deficiency, 2 patients had vitamin E deficiency, and 9 patients had mild‐to‐moderate vitamin D deficiency (none had severe deficiency). Both patients with vitamin E deficiency were symptomatic and had complete villous atrophy. Thirty‐one patients had insufficiency of 25 (OH) D, which was less than the reported frequency of vitamin D insufficiency in the general pediatric population in the United States in 2004. None of the patients were receiving vitamin supplements at the time of diagnosis.

Conclusions:

Fat‐soluble vitamin deficiencies are uncommon in children with new diagnosis of CD. Routine measuring of fat‐soluble vitamins levels may not be necessary.
Endothelial repair process and its relevance to longitudinal neointimal tissue patterns: comparing histology with
in silico
modelling
Authors: Tahir Hannan , Bona-Casas Carles , Narracott Andrew James , Iqbal Javaid , Gunn Julian , Lawford Patricia , Hoekstra Alfons G.
Published: March 2014

Re-establishing a functional endothelium following endovascular treatment is an important factor in arresting neointimal proliferation. In this study, both histology (
in vivo
) and computational simulations (
in silico
) are used to evaluate neointimal growth patterns within coronary arteries along the axial direction of the stent. Comparison of the growth configurations
in vivo
and
in silico
was undertaken to identify candidate mechanisms for endothelial repair. Stent, lumen and neointimal areas were measured from histological sections obtained from eight right coronary stented porcine arteries. Two re-endothelialization scenarios (endothelial cell (EC) random seeding and EC growth from proximal and distal ends) were implemented
in silico
to evaluate their influence on the morphology of the simulated lesions. Subject to the assumptions made in the current simulations, comparison between
in vivo
and
in silico
results suggests that endothelial growth does not occur from the proximal and distal ends alone, but is more consistent with the assumption of a random seeding process. This may occur either from the patches of endothelium which survive following stent implantation or from attachment of circulating endothelial progenitor cells.
Succession of hide–seek and pursuit–evasion at heterogeneous locations
Authors: Gal Shmuel , Casas Jérôme
Published: March 2014

Many interactions between searching agents and their elusive targets are composed of a succession of steps, whether in the context of immune systems, predation or counterterrorism. In the simplest case, a two-step process starts with a search-and-hide phase, also called a hide-and-seek phase, followed by a round of pursuit–escape. Our aim is to link these two processes, usually analysed separately and with different models, in a single game theory context. We define a matrix game in which a searcher looks at a fixed number of discrete locations only once each searching for a hider, which can escape with varying probabilities according to its location. The value of the game is the overall probability of capture after
k
looks. The optimal search and hide strategies are described. If a searcher looks only once into any of the locations, an optimal hider chooses it's hiding place so as to make all locations equally attractive. This optimal strategy remains true as long as the number of looks is below an easily calculated threshold; however, above this threshold, the optimal position for the hider is where it has the highest probability of escaping once spotted.
Context-dependent changes in motor control and kinematics during locomotion: modulation and decoupling
Authors: Foster Kathleen L. , Higham Timothy E.
Published: March 2014

Successful locomotion through complex, heterogeneous environments requires the muscles that power locomotion to function effectively under a wide variety of conditions. Although considerable data exist on how animals modulate both kinematics and motor pattern when confronted with orientation (i.e. incline) demands, little is known about the modulation of muscle function in response to changes in structural demands like substrate diameter, compliance and texture. Here, we used high-speed videography and electromyography to examine how substrate incline and perch diameter affected the kinematics and muscle function of both the forelimb and hindlimb in the green anole (Anolis carolinensis). Surprisingly, we found a decoupling of the modulation of kinematics and motor activity, with kinematics being more affected by perch diameter than by incline, and muscle function being more affected by incline than by perch diameter. Also, muscle activity was most stereotyped on the broad, vertical condition, suggesting that, despite being classified as a trunk-crown ecomorph, this species may prefer trunks. These data emphasize the complex interactions between the processes that underlie animal movement and the importance of examining muscle function when considering both the evolution of locomotion and the impacts of ecology on function.
Early warning signs in social-ecological networks
Authors: Suweis Samir , D'Odorico Paolo
Published: March 2014

A number of social-ecological systems exhibit complex behaviour associated with nonlinearities, bifurcations, and interaction with stochastic drivers. These systems are often prone to abrupt and unexpected instabilities and state shifts that emerge as a discontinuous response to gradual changes in environmental drivers. Predicting such behaviours is crucial to the prevention of or preparation for unwanted regime shifts. Recent research in ecology has investigated early warning signs that anticipate the divergence of univariate ecosystem dynamics from a stable attractor. To date, leading indicators of instability in systems with multiple interacting components have remained poorly investigated. This is a major limitation in the understanding of the dynamics of complex social-ecological networks. Here, we develop a theoretical framework to demonstrate that rising variance – measured, for example, by the maximum element of the covariance matrix of the network – is an effective leading indicator of network instability. We show that its reliability and robustness depend more on the sign of the interactions within the network than the network structure or noise intensity. Mutualistic, scale free and small world networks are less stable than their antagonistic or random counterparts but their instability is more reliably predicted by this leading indicator. These results provide new advances in multidimensional early warning analysis and offer a framework to evaluate the resilience of social-ecological networks.
Genome-wide signals of positive selection in human evolution
Authors: Enard David , Messer Philipp W. , Petrov Dmitri A.
Published: March 2014

The role of positive selection in human evolution remains controversial. On the one hand, scans for positive selection have identified hundreds of candidate loci, and the genome-wide patterns of polymorphism show signatures consistent with frequent positive selection. On the other hand, recent studies have argued that many of the candidate loci are false positives and that most genome-wide signatures of adaptation are in fact due to reduction of neutral diversity by linked deleterious mutations, known as background selection. Here we analyze human polymorphism data from the 1000 Genomes Project and detect signatures of positive selection once we correct for the effects of background selection. We show that levels of neutral polymorphism are lower near amino acid substitutions, with the strongest reduction observed specifically near functionally consequential amino acid substitutions. Furthermore, amino acid substitutions are associated with signatures of recent adaptation that should not be generated by background selection, such as unusually long and frequent haplotypes and specific distortions in the site frequency spectrum. We use forward simulations to argue that the observed signatures require a high rate of strongly adaptive substitutions near amino acid changes. We further demonstrate that the observed signatures of positive selection correlate better with the presence of regulatory sequences, as predicted by the ENCODE Project Consortium, than with the positions of amino acid substitutions. Our results suggest that adaptation was frequent in human evolution and provide support for the hypothesis of King and Wilson that adaptive divergence is primarily driven by regulatory changes.
Mirror, mirror on the wall… Who's the most opportunistic and compliant of them all?
Authors: Chen Yi-Su , Ro Young , Su Hung-Chung
Published: March 2014

Purpose

– The present research aims to revisit the relationships between buyer dependence on suppliers, relational norms between two parties in a buyer-supplier dyad, and a buyer's tendency to either engage in opportunistic behaviors or comply with a supplier's request as an exception condition. The authors adopt a supplier's perspective to examine the supplier's anticipation of the buyer's behaviors.

Design/methodology/approach

– Based on the original studies conducted by Joshi and Arnold, the authors extend both works using a similar methodology but with a different data sample. The previously validated buyer-supplier relationship supply disruption scenario presented in the original studies is rewritten from a supplier's perspective to examine the supplier's anticipation of the buyer's behaviors. Subjects are asked to assume the role of an account manager within the key supplier firm for an electronic equipment manufacturer and to respond to how they deal with the supplier's expectation of how the buying firm may behave in terms of compliance and opportunism.

Findings

– The results show that buyer dependence is positively related to buyer compliance behaviors and that this relationship holds irrespective of the buyer's or supplier's perspective on the supply disruption scenario and irrespective of professional or student subjects. Other findings include the contingency of the moderating effect of relational norms on the link between dependence and buyer compliance on various factors, and the existence of a boundary condition for the moderation effect of relational norms on the link between dependence and buyer opportunism.

Originality/value

– The study should prove valuable to academics and professionals alike. It reinforces the notion that buyers that are more dependent and reliant on suppliers are more willing to comply with supplier's needs. Also, it considers the possibility that supply chain agents from both the buyer and supplier sides may value the effect of relational norms differently, with suppliers perceiving that relational norms have more of a direct influence on a buyer's behavior. Lastly, the replication study extends the understanding of the generalizability of the original studies.
Blended learning: making an impact on assessment and self-reflection in accounting education
Authors: Dickfos Jennifer , Cameron Craig , Hodgson Catherine
Published: March 2014

Purpose

– The purpose of this paper is to describe the evolution of a blended learning strategy in a company law course for accounting students and to evaluate its impact on assessment and student self-reflection.

Design/methodology/approach

– A case study approach is used to describe the development of blended learning technologies within an elevator pitch assessment item in four cohorts over a two-year period. This is complemented by teacher observations, an online survey and student interviews to evaluate the assessment item, the technology used and its impact as a self-reflection and assessment tool.

Findings

– The case study reveals the benefits of blended learning technologies but also a series of logistical, assessment-related, behavioural and technological issues and how these issues were addressed. The preliminary evidence from the online survey and student interviews suggests that the blended learning technologies have facilitated flexibility in assessment (both from a student and teacher perspective), student self-reflection and fairness in assessment practices.

Originality/value

– The study identifies the benefits of and likely issues facing educators when considering the deployment of blended learning technologies to teach and assess oral communication skills. The paper contributes to pedagogy by describing the innovative use of video cameras in assessing elevator pitches and extends the literature on video presentations in higher education, in particular, its positive influence on student self-reflection.
Employer branding: strategy for improving employer attractiveness
Authors: Leekha Chhabra Neeti , Sharma Sanjeev
Published: March 2014

Purpose

– To examine the organizational attributes that attract final-year management students towards organizations. The paper aims to study the already adopted employer branding strategies and the preferred channel through which organizations should promote employer attractiveness. Based on previous studies and current findings, a conceptual model on employer branding process has been developed and presented.

Design/methodology/approach

– This article is based on semi-structured interviews, survey results and review of academic employer branding models.

Findings

– It was found that among the students, most preferred organizational attributes were organizational culture, brand name and compensation. Students rated job portal to be the preferred channel for employer attractiveness. The study showed that there exists a significant and positive correlation between strong brand image and likelihood to apply.

Research limitations/implications

– The survey sample was limited to private business schools only.

Practical implications

– One of the sources for hiring on which corporate rely heavily is private business schools. This study provides the employers an insight to make their strategies for employer branding more effective. In the process, it benefits the prospective employees as well.

Originality/value

– The study provides valuable inputs for formulating effective employer branding strategies. The novelty of the study is the conceptual model on the process of employer branding. One of the highlights of which is preferred communication channel for effectiveness of the strategies.