bluuebunny/crossref_metadata_2025 huggingface dataset:
Evolution of nanomicro structures on GaAs (001) surface under high temperature evaporation
Authors: Li Yulan , Hu Kai , Qu Yindong , Li Xiaolong , Xu Xingliang , Gao Lei , Medvids A. , Wang Zhiming M.
Published: November 2014

Protuberant mounds and micro‐nanoholes are prepared on the GaAs surface under Langmuir evaporation. It is demonstrated that mounds are oxidised Ga‐rich droplets with minute As. Through analysis of the experimental conditions of samples forming holes and mounds, the correlation between the two phenomena is presented. It is concluded that annealing time is the key factor in controlling the size of mounds and holes and that the annealing temperature is one predominant factor in deciding the evolution direction of the structure on GaAs—forming holes or protuberant mounds. The tuning over the GaAs surface morphology will be potentially applied in the preparation of quantum dots used for optical and electronic devices.
Current Concepts of Bone Tissue Engineering for Craniofacial Bone Defect Repair
Authors: Fishero BrianAlan , Kohli Nikita , Das Anusuya , Christophel JohnJared , Cui Quanjun
Published: November 2014

Craniofacial fractures and bony defects are common causes of morbidity and contribute to increasing health care costs. Successful regeneration of bone requires the concomitant processes of osteogenesis and neovascularization. Current methods of repair and reconstruction include rigid fixation, grafting, and free tissue transfer. However, these methods carry innate complications, including plate extrusion, nonunion, graft/flap failure, and donor site morbidity. Recent research efforts have focused on using stem cells and synthetic scaffolds to heal critical-sized bone defects similar to those sustained from traumatic injury or ablative oncologic surgery. Growth factors can be used to augment both osteogenesis and neovascularization across these defects. Many different growth factor delivery techniques and scaffold compositions have been explored yet none have emerged as the universally accepted standard. In this review, we will discuss the recent literature regarding the use of stem cells, growth factors, and synthetic scaffolds as alternative methods of craniofacial fracture repair.
Ascher Syndrome: Report of a Case with Early Manifestations
Authors: Molina Santiago , Medard Pablo , Galdeano Marcelo
Published: November 2014

Ascher syndrome is a disease of unknown etiology first described in 1920 by Ascher, an ophthalmologist from Prague. It presents with recurrent edema of the lip and upper eyelid resulting in double lip and blepharochalasis. In 10% of cases the idiopathic nontoxic thyroid enlargement also occurs. Because of its rarity, it is often undiagnosed. A case of early onset is presented with its respective surgical treatment and outcome.
Extreme fluctuations of the relative velocities between droplets in turbulent airflow
Authors: Saw Ewe-Wei , Bewley Gregory P. , Bodenschatz Eberhard , Sankar Ray Samriddhi , Bec Jérémie
Published: November 2014

We compare experiments and direct numerical simulations to evaluate the accuracy of the Stokes-drag model, which is used widely in studies of inertial particles in turbulence. We focus on statistics at the dissipation scale and on extreme values of relative particle velocities for moderately inertial particles (St < 1). The probability distributions of relative velocities in the simulations were qualitatively similar to those in the experiments. The agreement improved with increasing Stokes number and decreasing relative velocity. Simulations underestimated the probability of extreme events, which suggests that the Stokes drag model misses important dynamics. Nevertheless, the scaling behavior of the extreme events in both the experiments and the simulations can be captured by the same multi-fractal model.
Interband polarized absorption in InP polytypic superlattices
Authors: Faria Junior P. E. , Campos T. , Sipahi G. M.
Published: November 2014

Recent advances in growth techniques have allowed the fabrication of semiconductor nanostructures with mixed wurtzite/zinc-blende crystal phases. Although the optical characterization of these polytypic structures is well reported in the literature, a deeper theoretical understanding of how crystal phase mixing and quantum confinement change the output linear light polarization is still needed. In this paper, we theoretically investigate the mixing effects of wurtzite and zinc-blende phases on the interband absorption and in the degree of light polarization of an InP polytypic superlattice. We use a single 8 × 8 k⋅p Hamiltonian that describes both crystal phases. Quantum confinement is investigated by changing the size of the polytypic unit cell. We also include the optical confinement effect due to the dielectric mismatch between the superlattice and the vaccum and we show it to be necessary to match experimental results. Our calculations for large wurtzite concentrations and small quantum confinement explain the optical trends of recent photoluminescence excitation measurements. Furthermore, we find a high sensitivity to zinc-blende concentrations in the degree of linear polarization. This sensitivity can be reduced by increasing quantum confinement. In conclusion, our theoretical analysis provides an explanation for optical trends in InP polytypic superlattices, and shows that the interplay of crystal phase mixing and quantum confinement is an area worth exploring for light polarization engineering.
Improved Dyson series expansion for steady-state quantum transport beyond the weak coupling limit: Divergences and resolution
Authors: Thingna Juzar , Zhou Hangbo , Wang Jian-Sheng
Published: November 2014

We present a general theory to calculate the steady-state heat and electronic currents for nonlinear systems using a perturbative expansion in the system-bath coupling. We explicitly demonstrate that using the truncated Dyson-series leads to divergences in the steady-state limit, thus making it impossible to be used for actual applications. In order to resolve the divergences, we propose a unique choice of initial condition for the reduced density matrix, which removes the divergences at each order. Our approach not only allows us to use the truncated Dyson-series, with a reasonable choice of initial condition, but also gives the expected result that the steady-state solutions should be independent of initial preparations. Using our improved Dyson series we evaluate the heat and electronic currents up to fourth-order in system-bath coupling, a considerable improvement over the standard quantum master equation techniques. We then numerically corroborate our theory for archetypal settings of linear systems using the exact nonequilibrium Green's function approach. Finally, to demonstrate the advantage of our approach, we deal with the nonlinear spin-boson model to evaluate heat current up to fourth-order and find signatures of cotunnelling process.
Simulated optical absorption enhancement in random silicon nanohole structure for solar cell application
Authors: Hong Lei , Rusli  , Wang Xincai , Zheng Hongyu , Wang Hao , Yu Hongyu
Published: November 2014

We have conducted a systematic simulation study on light absorption in a silicon nanohole structure that has randomness introduced into its structural parameters, which include the hole radius, depth, and position. It is found that light absorption is enhanced for the random structures compared to their periodic counterparts. This is attributed to additional resonances induced by the structural disorders, broadening of the existing resonance, and lower optical reflection. The highest light absorption is obtained for the structure with randomness in hole position, which achieves a 12.7% enhancement compared with the periodic structure.
The effect of an anisotropic pressure of thermal particles on resistive wall mode stability
Authors: Berkery J. W. , Betti R. , Sabbagh S. A. , Guazzotto L. , Manickam J.
Published: November 2014

The effect of an anisotropic pressure of thermal particles on resistive wall mode stability in tokamak fusion plasmas is derived through kinetic theory and assessed through calculation with the MISK code [B. Hu et al., Phys. Plasmas 12, 0 57301 (2005)]. The fluid anisotropy is treated as a small perturbation on the plasma equilibrium and modeled with a bi-Maxwellian distribution function. A complete stability treatment without an assumption of high frequency mode rotation leads to anisotropic kinetic terms in the dispersion relation in addition to anisotropy corrections to the fluid terms. With the density and the average pressure kept constant, when thermal particles have a higher temperature perpendicular to the magnetic field than parallel, the fluid pressure-driven ballooning destabilization term is reduced. Additionally, the stabilizing kinetic effects of the trapped thermal ions can be enhanced. Together these two effects can lead to a modest increase in resistive wall mode stability.
Propulsive performance of a finite-temperature plasma flow in a magnetic nozzle with applied azimuthal current
Authors: Ferrario Lorenzo , Little Justin M. , Choueiri Edgar Y.
Published: November 2014

The plasma flow in a finite-electron-temperature magnetic nozzle, under the influence of an applied azimuthal current at the throat, is modeled analytically to assess its propulsive performance. A correction to the nozzle throat boundary conditions is derived by modifying the radial equilibrium of a magnetized infinite two-population cylindrical plasma column with the insertion of an external azimuthal body force for the electrons. Inclusion of finite-temperature effects, which leads to a modification of the radial density profile, is necessary for calculating the propulsive performance, which is represented by nozzle divergence efficiency and thrust coefficient. The solutions show that the application of the azimuthal current enhances all the calculated performance parameters through the narrowing of the radial density profile at the throat, and that investing power in this beam focusing effect is more effective than using the same power to pre-heat the electrons. The results open the possibility for the design of a focusing stage between the plasma source and the nozzle that can significantly enhance the propulsive performance of electron-driven magnetic nozzles.
Shear rheology and structural properties of chemically identical dendrimer-linear polymer blends through molecular dynamics simulations
Authors: Hajizadeh Elnaz , Todd B. D. , Daivis P. J.
Published: November 2014

We present nonequilibrium molecular dynamics (NEMD) simulation results for the miscibility, structural properties, and melt rheological behavior of polymeric blends under shear flow. The polymeric blends consist of chemically identical linear polymer chains (187 monomers per chain) and dendrimer polymers of generations g = 1–4. The number fraction x of the dendrimer species is varied (4%, 8%, and 12%) in the blend melt. The miscibility of blend species is measured, using the pair distribution functions gDL, gLL, and gDD. All the studied systems form miscible blend melts under the conditions investigated. We also study the effect of shear rate \documentclass[12pt]{minimal}\begin{document}$\dot{\gamma }$\end{document}γ̇ and dendrimer generation on inter-penetration between blend species for different blend systems. The results reveal that shear flow increases the interpenetration of linear chains toward the core of the dendrimers. We also calculate the shear-rate dependent radius of gyration and ratios of the eigenvalues of the gyration tensor to study the shear-induced deformation of the molecules in the blend. Melt rheological properties including the shear viscosity and first and second normal stress coefficients obtained from NEMD simulations at constant pressure are found to fall into the range between those of pure dendrimer and pure linear polymer melts.
Insensitivity of the octahedral spherical hohlraum to power imbalance, pointing accuracy, and assemblage accuracy
Authors: Huo Wen Yi , Liu Jie , Zhao Yiqing , Zheng Wudi , Lan Ke
Published: November 2014

The random radiation asymmetry in the octahedral spherical hohlraum [K. Lan et al., Phys. Plasmas 21, 0 10704 (2014)] arising from the power imbalance, pointing accuracy of laser quads, and the assemblage accuracy of capsule is investigated by using the 3-dimensional view factor model. From our study, for the spherical hohlraum, the random radiation asymmetry arising from the power imbalance of the laser quads is about half of that in the cylindrical hohlraum; the random asymmetry arising from the pointing error is about one order lower than that in the cylindrical hohlraum; and the random asymmetry arising from the assemblage error of capsule is about one third of that in the cylindrical hohlraum. Moreover, the random radiation asymmetry in the spherical hohlraum is also less than the amount in the elliptical hohlraum. The results indicate that the spherical hohlraum is more insensitive to the random variations than the cylindrical hohlraum and the elliptical hohlraum. Hence, the spherical hohlraum can relax the requirements to the power imbalance and pointing accuracy of laser facility and the assemblage accuracy of capsule.
Observation of three crystalline layers in hydrothermally grown BiFeO3 thick films
Authors: Lee T. K. , Sung K. D. , Kim T. H. , Ko J.-H. , Jung J. H.
Published: November 2014

We report the observation of three different crystalline layers in hydrothermally grown BiFeO3 (BFO) thick films on SrRuO3/SrTiO3 substrates. High-resolution X-ray diffraction and transmission electron microcopy results suggest that compressively strained, partially relaxed epitaxial layers, and a mixture of polycrystalline and amorphous BFO layers, were successively formed from the bottom to the top of the films. The resistance and capacitance of the mixed layer were significantly lower than those of the epitaxial layers. The atomic concentrations of Bi and Fe in the mixed layer were fluctuating for each point. Based on the observed three crystalline layers, we have discussed the growth mechanism and the leakage current of hydrothermally grown BFO thick films.
New non-linear photovoltaic effect in uniform bipolar semiconductor
Authors: Volovichev I.
Published: November 2014

A linear theory of the new non-linear photovoltaic effect in the closed circuit consisting of a non-uniformly illuminated uniform bipolar semiconductor with neutral impurities is developed. The non-uniform photo-excitation of impurities results in the position-dependant current carrier mobility that breaks the semiconductor homogeneity and induces the photo-electromotive force (emf). As both the electron (or hole) mobility gradient and the current carrier generation rate depend on the light intensity, the photo-emf and the short-circuit current prove to be non-linear functions of the incident light intensity at an arbitrarily low illumination. The influence of the sample size on the photovoltaic effect magnitude is studied. Physical relations and distinctions between the considered effect and the Dember and bulk photovoltaic effects are also discussed.
Thermal conductivity of bulk GaN—Effects of oxygen, magnesium doping, and strain field compensation
Authors: Simon Roland B. , Anaya Julian , Kuball Martin
Published: November 2014

The effect of oxygen doping (n-type) and oxygen (O)-magnesium (Mg) co-doping (semi-insulating) on the thermal conductivity of ammonothermal bulk GaN was studied via 3-omega measurements and a modified Callaway model. Oxygen doping was shown to significantly reduce thermal conductivity, whereas O-Mg co-doped GaN exhibited a thermal conductivity close to that of undoped GaN. The latter was attributed to a decreased phonon scattering rate due the compensation of impurity-generated strain fields as a result of dopant-complex formation. The results have great implications for GaN electronic and optoelectronic device applications on bulk GaN substrates.
Unconventional switching behavior in La0.7Sr0.3MnO3/La0.7Sr0.3CoO3 exchange-spring bilayers
Authors: Li Binzhi , Chopdekar Rajesh V. , Arenholz Elke , Mehta Apurva , Takamura Yayoi
Published: November 2014

We report on the observation of exchange-spring behavior in complex oxide bilayers composed of high coercivity ferromagnetic (FM) La0.7Sr0.3CoO3 (LSCO) and low coercivity FM La0.7Sr0.3MnO3 (LSMO). The magnetization process from each individual layer is revealed by a combination of bulk magnetometry and x-ray magnetic circular dichroism measurements. The results show unexpected magnetic switching behavior which deviates from conventional exchange-spring systems in that reversible switching occurs not only within the soft LSMO layer but is also accompanied by the switching of an interfacial LSCO layer. The origin of such exchange coupling is discussed in terms of charge redistribution at the interface.
Temperature sensibility of the birefringence properties in side-hole photonic crystal fiber filled with Indium
Authors: Reyes-Vera Erick , Gómez-Cardona Nelson D. , Chesini Giancarlo , Cordeiro Cristiano M. B. , Torres Pedro
Published: November 2014

We report on the temperature sensitivity of the birefringence properties of a special kind of photonic crystal fiber containing two side holes filled with Indium metal. The modulation of the fiber birefringence is accomplished through the stress field induced by the expansion of the metal. Although the fiber was made at low gas pressures during the indium infiltration process, the birefringence showed anomalous property at a relatively low temperature value, which is completely different from those reported in conventional-like fibers with two holes filled with metal. By modeling the anisotropic changes induced by the metal expansion to the refractive index within the fiber, we are able to reproduce the experimental results. Our results have practical relevance for the design of devices based on this technology.
Thermochemically evolved nanoplatelets of bismuth selenide with enhanced thermoelectric figure of merit
Authors: Ali Zulfiqar , Butt Sajid , Cao Chuanbao , Butt Faheem K. , Tahir Muhammad , Tanveer M. , Aslam Imran , Rizwan Muhammad , Idrees Faryal , Khalid Syed
Published: November 2014

We firstly present a simple thermochemical method to fabricate high-quality Bi2Se3 nanoplatelets with enhanced figure of merit using elemental bismuth and selenium powders as precursors. The crystal structure of as synthesized products is characterized via X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high resolution transmission electron microscopy (HRTEM) measurements. Morphological and chemical synthetic parameters are investigated through a series of experiments; thickness and composition of the platelets are well controlled in large scale production. Subsequently spark plasma sintering (SPS) is performed to fabricate n-type nanostructured bulk thermoelectric materials. Raman Spectroscopy of the two selected samples with approximately of 50 and 100 nm thicknesses shows three vibrational modes. The lower thickness sample exhibits the maximum red shift of about 2.17 cm-1 and maximum broadening of about 10 cm-1 by in-plane vibrational mode E2g. The enhanced value of figure of merit ∼0.41 is obtained for pure phase bismuth selenide to the best of our knowledge. We observe metallic conduction behavior while semiconducting behavior for nanostructured bismuth selenide is reported elsewhere which could be due to different synthetic techniques adopted. These results clearly suggest that our adopted synthetic technique has profound effect on the electronic and thermoelectric transport properties of this material.
In situ electrical characterization of palladium-based single electron transistors made by electromigration technique
Authors: Arzubiaga L. , Golmar F. , Llopis R. , Casanova F. , Hueso L. E.
Published: November 2014

We report the fabrication of single electron transistors (SETs) by feedback-controlled electromigration of palladium and palladium-nickel alloy nanowires. We have optimized a gradual electromigration process for obtaining devices consisting of three terminals (source, drain and gate electrodes), which are capacitively coupled to a metallic cluster of nanometric dimensions. This metal nanocluster forms into the inter-electrode channel during the electromigration process and constitutes the active element of each device, acting as a quantum dot that rules the electron flow between source and drain electrodes. The charge transport of the as-fabricated devices shows Coulomb blockade characteristics and the source to drain conductance can be modulated by electrostatic gating. We have thus achieved the fabrication and in situ measurement of palladium-based SETs inside a liquid helium cryostat chamber.
Colored wax-printed timers for two-dimensional and three-dimensional assays on paper-based devices
Authors: Weng Chen-Hsun , Chen Ming-Yi , Shen Chi-Hsiang , Yang Ruey-Jen
Published: November 2014

Microfluidic paper-based analytical devices (μPADs) are widely used for performing diagnostic assays. However, in many assays, time-delay valves are required to improve the sensitivity and specificity of the results. Accordingly, this study presents a simple, low-cost method for realizing time-delay valves using a color wax printing process. In the proposed approach, the time-delay effect is controlled through a careful selection of both the color and the saturation of the wax content. The validity of the proposed method is demonstrated by performing nitrite and oxalate assays using both a simple two-dimensional μPAD and a three-dimensional μPAD incorporating a colored wax-printed timer. The experimental results confirm that the flow time can be controlled through an appropriate selection of the color and the wax content. In addition, it is shown that nitrite and oxalate assays can be performed simultaneously on a single device. In general, the results presented in this study show that the proposed μPADs provide a feasible low-cost alternative to conventional methods for performing diagnostic assays.
Economization and Beyond: (Re)Composing Livelihoods in Maine, USA
Authors: Miller Ethan
Published: November 2014

Effectively engaging questions of sustainable regional development requires a substantive rethinking of the pervasive categories of ‘economy’, ‘society’, and ‘environment’. Çaliskan and Callon's analytical approach to “economization”, a tracing of the material-discursive production of the economic, is one important starting point for such work. Taking the contemporary field of economic development in the state of Maine (USA) as a case study, and drawing on fifteen recent interviews with a wide array of development professionals in this region, I pursue a critical analysis of regional economization and its accompanying constructions of society and environment. While affirming the economization concept as a useful tool for ethicopolitical analysis, I challenge this strategy at its limits. The tracing of successful framings and their overflows risks performatively affirming these constructions by assuming that the composition of collective well-being takes the ultimate and successful form of an ‘economy’. Analysis of economization must be accompanied by other explorations of the ways in which the work of regional economic developers might be articulated. I propose a reading of development processes and struggles in terms of the composition of livelihoods—destabilizing economy, society, and environment and beckoning toward a ‘transversal’ politics that might open up possibilities for unexpected alliances and alternative regional development pathways.
When Does Unequal become Unfair? Judging Claims of Environmental Injustice
Authors: Davoudi Simin , Brooks Elizabeth
Published: November 2014

The purpose of this paper is twofold. Firstly, it presents a pluralistic framework for justice that combines an expanded interpretation of distributive justice with concerns for recognition, participation, capability, and responsibility. It argues that the latter has not attracted the scholarly attention that it deserves in the environmental justice debate. Secondly, the paper demonstrates how this multidimensional framework can be applied in practice to inform practical judgments about particular environmental justice claims by using an example of traffic-related air pollution in the city of Newcastle upon Tyne in the United Kingdom.
Constructing Peripheral Cross-Border Regions in Planning: Territory—Network Interplay in the Barents Region
Authors: Zimmerbauer Kaj
Published: November 2014

This paper studies how supranational regions are built through the interplay of borders and networks. The focus is on how territory and network become manifest in planning, and in particular on the actual contexts in planning where the territorial discourse is emphasized. Conceptually, territory–network interplay is linked to recent discussions on relational/territorial space, multidimensionality of sociospatial relations, and thin and thick region building. The Barents Euro-Arctic Region is used here as an example, and the region's recent geoeconomic turn is studied first. The paper concludes that, despite geoeconomization, network is not dominant over territory as a key category in supranational region building. Although the contemporary (new) regionalist planning discourse emphasizes the institutionalization of network-oriented regional (economic) spaces without definitive boundaries, processes such as representing the region in branding or (re)defining who is eligible to join the official structures of cross-border cooperation entail a degree of territorial thinking and make use of the notions of boundedness and spatial symmetry. In planning practices networks commonly create the territory effect and vice versa. However, due to their different ontologies, network and territory can appear as separate or even contradictory discourses as well.
Learning through Policy Tourism: Circulating Bus Rapid Transit from South America to South Africa
Authors: Wood Astrid
Published: November 2014

Study tours, a form of ‘policy tourism’ in which local actors travel elsewhere to see best practice and meet with those in the exporting locality who implemented it, have become a basic tenet for policy exchange. In the pursuit of these lessons, hundreds of South African public transport enthusiasts visited South America, particularly Bogota, to learn of its thriving bus rapid transit (BRT) network. This paper evaluates the influence of these exchanges on BRT circulation and adoption—what takes place while delegates are overseas and how do these learning experiences influence the adoption and implementation of circulated forms of best practice? This paper reconnoiters these ‘mobility events’ and their outcomes to demonstrate theoretically that they are a necessary informal infrastructure through which best practice circulates: in particular, as a method for developing and strengthening social bonds between delegates and with hosts—relationships integral to policy adoption.
Developing Visibility Analysis for a Retail Store: A Pilot Study in a Bookstore
Authors: Lu Yi , Seo Hyun-Bo
Published: November 2014

Recent studies have confirmed that store layout influences a shopper's movement, purchasing behavior, and preference. However, the systematic and quantitative description of the layout of retail stores has been discussed in few studies. The analytic method for describing a layout presented in this study, with other refined analysis capabilities, is based on a prespecified set of visual targets rather than each occupiable location such as a room. The systematic visibility description of a layout enables quantitative comparison of multiple locations within one layout and across multiple physical layouts. An observation exercise took place in a bookstore and the target-based systematic analysis showed, while nontarget-based systematic analysis did not show, that a product with high visibility from major paths, where shoppers tended to have more visual contact, had more product engagement. The research not only confirmed the impact of store layout but also showed how the layout affected shoppers' behavior.
Media Practices and Urban Politics: Conceptualizing the Powers of the Media-Urban Nexus
Authors: Rodgers Scott , Barnett Clive , Cochrane Allan
Published: November 2014

The spatial imaginations of media studies and urban studies are increasingly aligned, illustrated by a growing literature on what can be identified as the media—urban nexus. This nexus has attracted scholarly interest not only as a cultural phenomenon, but also as a site of emergent political dynamics. We suggest that literature on the media—urban nexus points to the always-already present conditions of possibility for a translocal, relational urban politics. Current conceptualizations of the politics of urbanized media, however, tend to fall into one of two registers: conflicts over the access to and regulation of urban media spaces; or the silent politics that media inscribe into the affective textures of urban life. Both tend to envision media as instrumental supplements to politics, overestimating the powers of ‘media’ within urban living. Drawing on recent uses of practice theory in media studies, we highlight how thinking of media-in-practices provides a basis for more nuanced conceptualizations of the powers of the media—urban nexus. Fully realizing this conceptualization requires that the restriction of the insights of practice theory to everyday life be lifted. An expanded view of media practices is required, one which emphasizes the coordination between organized fields of communication and everyday urbanized media practices.
Temporal frames of reference in three Germanic languages: Individual consistency, interindividual consensus, and cross-linguistic variability
Authors: Rothe-Wulf Annelie , Beller Sieghard , Bender Andrea
Published: November 2014

A task like “moving a meeting forward” reveals the ambiguity inherent in temporal references. That speakers of U.S. English do not agree on how to solve it is well established: Roughly one half moves the meeting futurewards, the other half pastwards. But the extent to which individual speakers, rather than groups of speakers, consider such phrases as ambiguous has not been scrutinized. Does the split in readings result from a lack of intraindividual consistency or from a lack of interindividual consensus? And how specific is U.S. English in this regard when compared to other closely related Germanic languages? Based on a taxonomy of spatiotemporal frames of reference (FoRs), we conducted two experiments with speakers of Swedish, U.S. English, and German to assess individual preferences for temporal FoRs, intra- and cross-linguistic variability, consistency and long-term stability of these preferences, and possible effects of priming a spatial FoR. The data reveal cross-linguistic differences, both in terms of which temporal FoRs speakers prefer (the absolute FoR in Sweden, the intrinsic FoR in German, and both of these in the US) and in terms of the extent to which these preferences are shared and stable (high consensus and consistency in Sweden and Germany, and low consensus and partial consistency in the US). Overall, no effect of spatial priming was observed; only speakers of U.S. English with a baseline preference for the absolute temporal FoR seemed to be susceptible to spatial priming. Thus, the assumption that temporal references are affected by spatial references is only weakly supported.
Semantic classification of pictures and words
Authors: Taikh Alex , Hargreaves Ian S. , Yap Melvin J. , Pexman Penny M.
Published: November 2014

We provide new behavioural norms for semantic classification of pictures and words. The picture stimuli are 288 black and white line drawings from the International Picture Naming Project ([Székely, A., Jacobsen, T., D'Amico, S., Devescovi, A., Andonova, E., Herron, D., et al. (2004). A new on-line resource for psycholinguistic studies. Journal of Memory & Language, 51, 247–250]). We presented these pictures for classification in a living/nonliving decision, and in a separate version of the task presented the corresponding word labels for classification. We analyzed behavioural responses to a subset of the stimuli in order to explore questions about semantic processing. We found multiple semantic richness effects for both picture and word classification. Further, while lexical-level factors were related to semantic classification of words, they were not related to semantic classification of pictures. We argue that these results are consistent with privileged semantic access for pictures, and point to ways in which these data could be used to address other questions about picture processing and semantic memory.
STIM1- and Orai1-mediated Ca2+ oscillation orchestrates invadopodium formation and melanoma invasion
Authors: Sun Jianwei , Lu Fujian , He Huifang , Shen Junling , Messina Jane , Mathew Rahel , Wang Dapeng , Sarnaik Amod A. , Chang Wei-Chiao , Kim Minjung , Cheng Heping , Yang Shengyu
Published: November 2014

Ca2+ signaling has been increasingly implicated in cancer invasion and metastasis, and yet, the underlying mechanisms remained largely unknown. In this paper, we report that STIM1- and Orai1-mediated Ca2+ oscillations promote melanoma invasion by orchestrating invadopodium assembly and extracellular matrix (ECM) degradation. Ca2+ oscillation signals facilitate invadopodial precursor assembly by activating Src. Disruption of Ca2+ oscillations inhibited invadopodium assembly. Furthermore, STIM1 and Orai1 regulate the proteolysis activity of individual invadopodia. Mechanistically, Orai1 blockade inhibited the recycling of MT1–matrix metalloproteinase (MMP) to the plasma membrane and entrapped MT1-MMP in the endocytic compartment to inhibit ECM degradation. STIM1 knockdown significantly inhibited melanoma lung metastasis in a xenograft mouse model, implicating the importance of this pathway in metastatic dissemination. Our findings provide a novel mechanism for Ca2+-mediated cancer cell invasion and shed new light on the spatiotemporal organization of store-operated Ca2+ signals during melanoma invasion and metastasis.
CXCR4 and a cell-extrinsic mechanism control immature B lymphocyte egress from bone marrow
Authors: Beck Thomas C. , Gomes Ana Cordeiro , Cyster Jason G. , Pereira João P.
Published: November 2014

Leukocyte residence in lymphoid organs is controlled by a balance between retention and egress-promoting chemoattractants sensed by pertussis toxin (PTX)–sensitive Gαi protein–coupled receptors (GPCRs). Here, we use two-photon intravital microscopy to show that immature B cell retention within bone marrow (BM) was strictly dependent on amoeboid motility mediated by CXCR4 and CXCL12 and by α4β1 integrin–mediated adhesion to VCAM-1. However, B lineage cell egress from BM is independent of PTX-sensitive GPCR signaling. B lineage cells expressing PTX rapidly exited BM even though their motility within BM parenchyma was significantly reduced. Our experiments reveal that when immature B cells are near BM sinusoids their motility is reduced, their morphology is predominantly rounded, and cells reverse transmigrate across sinusoidal endothelium in a largely nonamoeboid manner. Immature B cell egress from BM was dependent on a twofold CXCR4 down-regulation that was antagonized by antigen-induced BCR signaling. This passive mode of cell egress from BM also contributes significantly to the export of other hematopoietic cells, including granulocytes, monocytes, and NK cells, and is reminiscent of erythrocyte egress.
Once upon a larva: revisiting the relationship between feeding success and growth in fish larvae
Authors: Pepin Pierre , Robert Dominique , Bouchard Caroline , Dower John F. , Falardeau Marianne , Fortier Louis , Jenkins Gregory P. , Leclerc Véronique , Levesque Keith , Llopiz Joel K. , Meekan Mark G. , Murphy Hannah M. , Ringuette Marc , Sirois Pascal , Sponaugle Su
Published: November 2014

Variations in larval fish growth rates are largely the result of variability in biotic and abiotic characteristics of the feeding environment experienced by each individual. An assessment of an individual's overall feeding success (i.e. accumulation of utilizable organic matter) can best be achieved at the time of capture when the relationships among environment, short-term feeding success as defined by gut content and long-term feeding success as defined by accumulated growth can be contrasted. Here, we investigated the relationships between average growth, feeding success, and variability in individual growth and feeding rates across a range of taxa based on a synthesis of studies in which stomach content and otolith growth were measured in the same individuals. Instantaneous measures of feeding success were highly variable and demonstrated a positive yet somewhat limited association with growth rates across all taxa. The strength of the feeding-growth relationships among taxa, and cohorts within taxa, was reflected in the autocorrelation of individual growth rates, suggesting that stable growth was achieved through consistent feeding success. However, when viewed at the individual level, faster growth was achieved in individuals with more variable growth rates, and by inference more variable past feeding success. The dichotomy in these underlying relationships may point to the importance of stochastic events in the development of exceptional individuals in a population, and may be linked to how surplus energy is allocated to individual growth rates. The positive correlation found between feeding success and growth in all taxa is consistent with the growth-survival paradigm for the larval stage of fish. However, both the correlation between feeding success and growth and the serial correlation of growth time-series was greatest in fast-growing species, suggesting that the potential for an early “critical period” regulating survival varies among species, reaching a maximum in fast-growing fish.
Constructing cities, deconstructing scaling laws
Authors: Arcaute Elsa , Hatna Erez , Ferguson Peter , Youn Hyejin , Johansson Anders , Batty Michael
Published: November 2014

Cities can be characterized and modelled through different urban measures. Consistency within these observables is crucial in order to advance towards a science of cities. Bettencourt
et al
. have proposed that many of these urban measures can be predicted through universal scaling laws. We develop a framework to consistently define cities, using commuting to work and population density thresholds, and construct thousands of realizations of systems of cities with different boundaries for England and Wales. These serve as a laboratory for the scaling analysis of a large set of urban indicators. The analysis shows that population size alone does not provide us enough information to describe or predict the state of a city as previously proposed, indicating that the expected scaling laws are not corroborated. We found that most urban indicators scale linearly with city size, regardless of the definition of the urban boundaries. However, when nonlinear correlations are present, the exponent fluctuates considerably.
Spatial analyses of wildlife contact networks
Authors: Davis Stephen , Abbasi Babak , Shah Shrupa , Telfer Sandra , Begon Mike
Published: November 2014

Datasets from which wildlife contact networks of epidemiological importance can be inferred are becoming increasingly common. A largely unexplored facet of these data is finding evidence of spatial constraints on who has contact with whom, despite theoretical epidemiologists having long realized spatial constraints can play a critical role in infectious disease dynamics. A graph dissimilarity measure is proposed to quantify how close an observed contact network is to being purely spatial whereby its edges are completely determined by the spatial arrangement of its nodes. Statistical techniques are also used to fit a series of mechanistic models for contact rates between individuals to the binary edge data representing presence or absence of observed contact. These are the basis for a second measure that quantifies the extent to which contacts are being mediated by distance. We apply these methods to a set of 128 contact networks of field voles (Microtus agrestis) inferred from mark–recapture data collected over 7 years and from four sites. Large fluctuations in vole abundance allow us to demonstrate that the networks become increasingly similar to spatial proximity graphs as vole density increases. The average number of contacts,, was (i) positively correlated with vole density across the range of observed densities and (ii) for two of the four sites a saturating function of density. The implications for pathogen persistence in wildlife may be that persistence is relatively unaffected by fluctuations in host density because at low densityis low but hosts move more freely, and at high densityis high but transmission is hampered by local build-up of infected or recovered animals.
Women, science and suffrage in World War I
Authors: Fara Patricia
Published: November 2014

Oh! This War! How it is tearing down walls and barriers, and battering in fast shut doors …

Women's Liberal Review
, 1915

World War I is often said to have benefited British women by giving them the vote and by enabling them to take on traditionally male roles, including ones in science, engineering and medicine. In reality, conventional hierarchies were rapidly re-established after the Armistice. Concentrating mainly on a small group of well-qualified scientific and medical women, marginalized at the time and also in the secondary literature, I review the attitudes they experienced and the work they undertook during and immediately after the war. The effects of century-old prejudices are still felt today.
Caroline Herschel: agency and self-presentation
Authors: Winterburn Emily
Published: November 2014

Caroline Herschel was rare among her female contemporaries in gaining public recognition for her work in science, yet her role in this process and her role in designing her training have never previously been studied. We know that access to education and participation in science was different for men and women in the eighteenth century. However, drawing on feminist, pedagogical and biographical approaches to history, I argue that although access depended on a variety of factors, a more consistent gender divide came in lessons on how to learn, and in what was regarded as appropriate behaviour. Caroline's skill—so often misunderstood—was to be aware of the differences and to use them to her own advantage.
Out-of-unison resonance in weakly nonlinear coupled oscillators
Authors: Hill T. L. , Cammarano A. , Neild S. A. , Wagg D. J.
Published: November 2014

Resonance is an important phenomenon in vibrating systems and, in systems of nonlinear coupled oscillators, resonant interactions can occur between constituent parts of the system. In this paper, out-of-unison resonance is defined as a solution in which components of the response are 90° out-of-phase, in contrast to the in-unison responses that are normally considered. A well-known physical example of this is whirling, which can occur in a taut cable. Here, we use a normal form technique to obtain time-independent functions known as backbone curves. Considering a model of a cable, this approach is used to identify out-of-unison resonance and it is demonstrated that this corresponds to whirling. We then show how out-of-unison resonance can occur in other two degree-of-freedom nonlinear oscillators. Specifically, an in-line oscillator consisting of two masses connected by nonlinear springs—a type of system where out-of-unison resonance has not previously been identified—is shown to have specific parameter regions where out-of-unison resonance can occur. Finally, we demonstrate how the backbone curve analysis can be used to predict the responses of forced systems.
Intraspecific facilitation by allelochemical mediated grazing protection within a toxigenic dinoflagellate population
Authors: John Uwe , Tillmann Urban , Hülskötter Jennifer , Alpermann Tilman J. , Wohlrab Sylke , Van de Waal Dedmer B.
Published: November 2014

Dinoflagellates are a major cause of harmful algal blooms (HABs), with consequences for coastal marine ecosystem functioning and services.
Alexandrium fundyense
(previously
Alexandrium tamarense
) is one of the most abundant and widespread toxigenic species in the temperate Northern and Southern Hemisphere and produces paralytic shellfish poisoning toxins as well as lytic allelochemical substances. These bioactive compounds may support the success of
A. fundyense
and its ability to form blooms. Here we investigate the impact of grazing on monoclonal and mixed set-ups of highly (Alex2) and moderately (Alex4) allelochemically active
A. fundyense
strains and a non-allelochemically active conspecific (Alex5) by the heterotrophic dinoflagellate
Polykrikos kofoidii
. While Alex4 and particularly Alex5 were strongly grazed by
P. kofoidii
when offered alone, both strains grew well in the mixed assemblages (Alex4 + Alex5 and Alex2 + Alex5). Hence, the allelochemical active strains facilitated growth of the non-active strain by protecting the population as a whole against grazing. Based on our results, we argue that facilitation among clonal lineages within a species may partly explain the high genotypic and phenotypic diversity of
Alexandrium
populations. Populations of
Alexandrium
may comprise multiple cooperative traits that act in concert with intraspecific facilitation, and hence promote the success of this notorious HAB species.
Mating portfolios: bet-hedging, sexual selection and female multiple mating
Authors: Garcia-Gonzalez Francisco , Yasui Yukio , Evans Jonathan P.
Published: November 2014

Polyandry (female multiple mating) has profound evolutionary and ecological implications. Despite considerable work devoted to understanding why females mate multiply, we currently lack convincing empirical evidence to explain the adaptive value of polyandry. Here, we provide a direct test of the controversial idea that bet-hedging functions as a risk-spreading strategy that yields multi-generational fitness benefits to polyandrous females. Unfortunately, testing this hypothesis is far from trivial, and the empirical comparison of the across-generations fitness payoffs of a polyandrous (bet hedger) versus a monandrous (non-bet hedger) strategy has never been accomplished because of numerous experimental constraints presented by most ‘model’ species. In this study, we take advantage of the extraordinary tractability and versatility of a marine broadcast spawning invertebrate to overcome these challenges. We are able to simulate multi-generational (geometric mean) fitness among individual females assigned simultaneously to a polyandrous and monandrous mating strategy. Our approaches, which separate and account for the effects of sexual selection and pure bet-hedging scenarios, reveal that bet-hedging, in addition to sexual selection, can enhance evolutionary fitness in multiply mated females. In addition to offering a tractable experimental approach for addressing bet-hedging theory, our study provides key insights into the evolutionary ecology of sexual interactions.