bluuebunny/crossref_metadata_2025 huggingface dataset:
Impact of light soaking and thermal annealing on amorphous silicon thin film performance
Authors: Pierro M. , Bucci F. , Cornaro C.
Published: February 2015

Nowadays, there is a wide debate in literature related to the silicon thin films seasonal performance. Amorphous modules seem to react positively to the temperature, while the temperature parameters indicate a negative thermal response. Periodic fluctuations of nominal power due to light soaking and thermal annealing effects are observed. On the other hand, the module temperature reached in some open rack plants seems too low to activate annealing power regeneration process so that the seasonal performance trend may depend mainly on other effects such as spectral or irradiance. In the following paper, a model that allows to calculate the impact of all the phenomena that affect the photovoltaic performance is used. The light soaking and thermal annealing contributions are measured from outdoor data using two different methods. Both methods lead to similar results, and the model is able to reproduce the seasonal performance with an acceptable level of reliability on the day, hour, minute time scale. An analysis of each effect contribution to the seasonal performance is also provided. Thus, main open questions related to a‐Si thin films performance such as positive reaction to temperature and seasonal fluctuations are discussed. Copyright © 2015 John Wiley & Sons, Ltd.
DC Discharge Plasma Modification of Chitosan Films: An Effect of Chitosan Chemical Structure
Authors: Demina Tatiana S. , Drozdova Maria G. , Yablokov Michail Y. , Gaidar Anna I. , Gilman Alla B. , Zaytseva‐Zotova Daria S. , Markvicheva Elena A. , Akopova Tatiana A. , Zelenetskii Alexander N.
Published: February 2015

Surface plasma treatment of chitosan films is a widely used technique to control a variety of their properties, such as permeability, hemostatic activity and ability to support cell adhesion, proliferation and growth. Among other factors to be controlled, the chemical structure of initial chitosan is rarely taken into consideration. This work is aimed to highlight this factor by the example of low pressure direct‐current discharge of various chitosan film samples. Contact angle measurements, X‐ray photoelectron spectroscopy and scanning electron microscopy revealed differences in the film surface properties of the initial and plasma‐treated films. The effect of the plasma treatment on cell viability of L929 mouse fibroblasts was studied by MTT‐assay.
Effect of Argon or Helium on the CO2 Conversion in a Dielectric Barrier Discharge
Authors: Ramakers Marleen , Michielsen Inne , Aerts Robby , Meynen Vera , Bogaerts Annemie
Published: February 2015

This paper demonstrates that the CO2 conversion in a dielectric barrier discharge rises drastically upon addition of Ar or He, and the effect is more pronounced for Ar than for He. The effective CO2 conversion, on the other hand, drops upon addition of Ar or He, which is logical due to the lower CO2 content in the gas mixture, and the same is true for the energy efficiency, because a considerable fraction of the energy is then consumed into ionization/excitation of Ar or He atoms. The higher absolute CO2 conversion upon addition of Ar or He can be explained by studying in detail the Lissajous plots and the current profiles. The breakdown voltage is lower in the CO2/Ar and CO2/He mixtures, and the discharge gap is more filled with plasma, which enhances the possibility for CO2 conversion. The rates of electron impact excitation–dissociation of CO2, estimated from the electron densities and mean electron energies, are indeed higher in the CO2/Ar and (to a lower extent) in the CO2/He mixtures, compared to the pure CO2 plasma. Moreover, charge transfer between Ar+ or Ar2+ ions and CO2, followed by electron‐ion dissociative recombination of the CO2+ ions, might also contribute to, or even be dominant for the CO2 dissociation. All these effects can explain the higher CO2 conversion, especially upon addition of Ar, but also upon addition of He.
Life‐threatening, giant pneumatoceles in the course of surfactant protein C deficiency
Authors: Sismanlar Tugba , Aslan Ayse Tana , Griese Matthias
Published: February 2015

Chronic interstitial lung diseases are rare in childhood and can present with a wide spectrum of histological abnormalities and radiological‐clinical phenotypes. A 17‐month‐old female infant with malnutrition, recurrent lower respiratory tract infections, and failure to thrive since 3 months of age was diagnosed as surfactant protein C deficiency. Diffuse, giant, and life‐threatening pneumatoceles developed during the course. They were treated with empiric drug treatment and oxygen support, and resolved rapidly. Substantial clinical and radiological improvement was observed 1 year after treatment initiation. Large‐giant pneumatoceles can develop in the course of surfactant protein C deficiency and may be associated with biopsy. They can resolve with medical treatment. If available, genetic testing should be attempted as a first step for diagnosis. Pediatr Pulmonol. 2015; 50:E25–E28. © 2015 Wiley Periodicals, Inc.
Molecular architecture of novel potentially bioactive (co)oligoesters containing pesticide moieties established by electrospray ionization multistage mass spectrometry
Authors: Kwiecień Iwona , Bałakier Tomasz , Jurczak Janusz , Kowalczuk Marek , Adamus Grażyna
Published: February 2015

Rationale

Pesticides are commonly used in agriculture to ensure high crop yield; however, because of their low resistance to environmental conditions, a large amount of pesticides does not reach target pests and becomes an environmental pollutant. One of the ways to reduce these drawbacks is synthesis of polymeric systems, which allows for controlled release of pesticides for a prolonged period of time. Herein we report the synthesis and characterization of novel potentially bioactive (co)oligoesters with bioactive moieties (selected from pesticides) which are covalently linked along an oligoester backbone.

Methods

The delivery systems of pesticides were prepared via anionic ring‐opening polymerization of β‐substituted β‐lactones containing bioactive moieties as a pendant group selected from pesticides and their copolymerization with β‐butyrolactone in the presence of carboxylates as initiators. Electrospray ionization multistage mass spectrometry (ESI‐MSn) supported by 1H NMR were applied in order to establish the structure, at a molecular level, of the new biodegradable oligomeric release system of selected pesticides.

Results

Based on ESI‐MSn analyses, the structures of the resulting (co)oligoesters were established at the molecular level. The ESI‐MS/MS allowed to confirm the structures of end groups and to determine the composition of individual (co)oligoester molecules which contained one, two or three bioactive molecules per (co)oligomer. Additionally, it was shown that fragmentation of selected ions of potentially bioactive (co)oligoesters proceeded via random breakage of ester bonds along the oligomer chain and ester bonds of the bioactive pendant group.

Conclusions

An analytical method for detailed structural characterization at the molecular level of potentially bioactive (co)oligoesters has been developed. These results are important in the analysis of designed biodegradable polymeric controlled‐release systems of pesticides with potential agricultural applications. Copyright © 2015 John Wiley & Sons, Ltd.
Unlocking the Hidden Value of Concepts: A Cognitive Approach to Business Model Innovation
Authors: Martins Luis L. , Rindova Violina P. , Greenbaum Bruce E.
Published: February 2015

We advance a theory of how business models can be innovated proactively in the absence of exogenous changes, through processes of generative cognition. We contribute to the cognitive perspective in strategy by analyzing business models as schemas that organize managerial understandings about the design of firms' value‐creating activities and exchanges and by theorizing how they can be innovated through processes for proactive schema change. Drawing on cognitive psychology research on two major cognitive processes through which individuals change their schema to cope with novelty, analogical reasoning and conceptual combination, we theorize firm‐level strategic processes for designing innovative business models. Copyright © 2015 Strategic Management Society.
Business Model Innovation Performance: When does Adding a New Business Model Benefit an Incumbent?
Authors: Kim Stephen K. , Min Sungwook
Published: February 2015

Many incumbent firms respond to the emergence of a disruptive business model by adding the business model into their existing ones. But, not all incumbents perform better after adding new business models to their existing ones; that raises the question about the conditions under which adding a new business model improves incumbent performance. We develop a theoretical framework to address that question. After identifying two types of incumbent assets, complementary and conflicting, we highlight the influence of two managerial choices—timing and organizational mode of the new business model addition—that create opportunities to translate the potential provided by incumbent assets into higher performance. The proposed discriminating alignment thesis states that incumbent performance after new business model addition improves when the incumbent firm aligns complementary assets with earlier addition of the new business model and conflicting assets with an autonomous business unit for the new business model. To test these hypotheses, we analyzed the performance change of those physical store‐based retailers that added online retailing as a new business model. The test results supported all hypotheses, and key theoretical and managerial implications are presented. Copyright © 2015 Strategic Management Society.
Strategy dynamics: Agency, path dependency, and self‐organized emergence
Authors: Thietart Raymond‐Alain
Published: February 2015

Analysis of a 42‐year strategic journey at a large multinational firm exposes the dynamics behind its strategic evolution. Grounded on a complexity science paradigm, this article challenges our understanding of the role of agency in strategic timing while adding conceptual and methodological innovations. Based on micro and macro approaches, qualitative interpretations, and econometric studies, the results tend to show that while agency partly produces strategy dynamics and timing of actions, strategic evolution (when not random) is largely emergent and driven by its past. These findings move the understanding of strategic evolution and timing away from a strategic choice perspective and toward a complex combination of agency, causal determinism, and self‐organization.Copyright © 2015 John Wiley & Sons, Ltd.
Effect of Mo on Nano‐Precipitation Behavior and Microscopic Mechanical Characteristics of Ferrite
Authors: Xu Yang , Sun Ming‐Xue , Zhou Yan‐Lei , Liu Zhen‐Yu , Wang Guo‐Dong
Published: February 2015

The undercooling austenite transformation, nano‐precipitation behaviors, and microscopic mechanical properties of ferrite in Nb‐Ti‐Mo and Nb‐Ti bearing steels have been studied by thermal simulation experiments, Vickers hardness, transmission electron microscopy and nanohardness indentation. The results show that Mo tends to promote the austenite→bainite transformation and refine ferrite grain, nano‐precipitates and sheet spacing. There are two different precipitation behaviors (interphase precipitation and random dispersive precipitation) in ferrite for the two tested steels. The EDS analysis indicates that these particles are (Nb, Ti)(C, N) for the size of more than 150 nm, (Nb, Ti)C and TiC for the size of less than 30 nm. Mo is not found in the precipitate particles of Nb‐Ti‐Mo steel. Nanoindentation results demonstrate that the values of nanohardness and Young's modulus are 4.13 and 249.3 GPa for Nb‐Ti steel, 4.41 and 232.0 GPa for Nb‐Ti‐Mo steel, respectively. Mo could increase nanohardness of ferrite 280 MPa, and reduce Young's modulus of ferrite 17.3 GPa. Nb‐Ti‐Mo steel has a higher work hardening rate compared with Nb‐Ti steel.
On the Influence of Interpersonal Relations on Business Practices in Latin America: A Comparison with the Chinese Guanxi and the Arab Wasta
Authors: Velez‐Calle Andres , Robledo‐Ardila Cristina , Rodriguez‐Rios Juan David
Published: February 2015

The connection between interpersonal relationships and business practices is currently an object of study in the field of international business. The authors have identified a significant body of research literature characterizing this phenomenon in China, where it is denominated as guanxi, as well as a recent interest of the academy in studying the Arab wasta (i.e., clout or influence). The authors argue that a similar phenomenon occurs in Latin America and identify patterns similar to those of guanxi and wasta in a cultural artifact called compadrazgo. The article offers insight for managers and individuals interested in doing business in Latin America. © 2015 Wiley Periodicals, Inc.
Objects exhibit body model like shape distortions
Authors: Saulton Aurelie , Dodds Trevor J. , Bülthoff Heinrich H. , de la Rosa Stephan
Published: February 2015

Accurate knowledge about size and shape of the body derived from somatosensation is important to locate one’s own body in space. The internal representation of these body metrics (body model) has been assessed by contrasting the distortions of participants’ body estimates across two types of tasks (localization task vs. template matching task). Here, we examined to which extent this contrast is linked to the human body. We compared participants’ shape estimates of their own hand and non-corporeal objects (rake, post-it pad, CD-box) between a localization task and a template matching task. While most items were perceived accurately in the visual template matching task, they appeared to be distorted in the localization task. All items’ distortions were characterized by larger length underestimation compared to width. This pattern of distortion was maintained across orientation for the rake item only, suggesting that the biases measured on the rake were bound to an item-centric reference frame. This was previously assumed to be the case only for the hand. Although similar results can be found between non-corporeal items and the hand, the hand appears significantly more distorted than other items in the localization task. Therefore, we conclude that the magnitude of the distortions measured in the localization task is specific to the hand. Our results are in line with the idea that the localization task for the hand measures contributions of both an implicit body model that is not utilized in landmark localization with objects and other factors that are common to objects and the hand.
The use of block counts, mark‐resight and distance sampling to estimate population size of a mountain‐dwelling ungulate
Authors: Corlatti Luca , Fattorini Lorenzo , Nelli Luca
Published: February 2015

Population size estimates represent indispensable tools for many research programs and for conservation or management issues. Mountain ungulates in open areas are often surveyed through ground counts that normally underestimate population size. While the use of sample counts is desirable, few studies have compared different probabilistic approaches to estimate population size in thistaxon. We compared the size estimates of a male population of Alpine chamois using mark‐resight and line transect sampling methods, while block counts were used to obtain the minimum number of males alive in the study area. Surveys were conducted within the Gran Paradiso National Park (Italy), in August–September 2013, using block counts along purposely selected trails and vantage points, mark‐resight over 5 consecutive resightings from vantage points and trails, and line transect sampling along 12 transects repeated 8 times. Block counts yielded a minimum number of males alive in the population ofn= 72 individuals. This value was greater than the upper bound of the 95 % confidence interval achieved using line transect sampling {n= 54, CV = 14 % [95 % CI (40, 71)]} while mark‐resight yielded a more realistic result ofn= 93 individuals {CV = 18 % [95 % CI (63, 137)]}. Our results suggest that line transect sampling performed poorly in the Alpine environment, leading to underestimates of population size, likely due to violations of some assumptions imposed by the rugged nature of the terrain. The mark‐resight yielded lower precision, possibly due to the limited number of marked individuals and resighting occasions, but it provided robustness and accurate estimates as marks were evenly distributed among animals.
Oleogels from Glycerol‐Based Lyotropic Liquid Crystals: Phase Diagrams and Structural Characterization
Authors: Cegla‐Nemirovsky Yael , Aserin Abraham , Garti Nissim
Published: February 2015

In the course of our studies on structured reverse lyotropic liquid crystals (LLC) as oleogels, a system was designed with the desired physical and rheology properties for cosmetic and pharmaceutical applications. The aqueous phase was partially replaced by glycerol to minimize bacteriological problems and obtain specific rheology characteristics. The constructed phase diagrams are based on ternary mixtures of glycerol monooleate (GMO), decane, water, and glycerol. The main lyotropic mesophase obtained in this study was reverse hexagonal derived from dilution line 8:2 (72 wt% GMO and 18 wt% decane) and 10 wt% water; or water:glycerol (wt ratios 3:1 and 1:1) mixture. It was found that heat‐cool fluctuation caused formation of new pseudo‐equilibrium structures with mesomorphic transformations to more fluid and less ordered mesostructures. Replacing up to 50 wt% of the water by glycerol significantly increases the gel phase region in the phase diagram, meaning more structural compositional options. The structural parameters were determined using cross‐polarized light microscopy (CPLM), differential scanning calorimeter (DSC), powder X‐ray diffraction (PXRD), and small angle X‐ray scattering (SAXS). Rheological measurements revealed viscoelastic properties of lyotropic liquid crystals with a decrease in the elasticity (G′), plasticity (G″), and complex viscosity (η*), as a function of increasing the glycerol content.
miR‐10a controls glioma migration and invasion through regulating epithelial–mesenchymal transition via EphA8
Authors: Yan Yan , Wang Qin , Yan Xiao-Ling , Zhang Yi , Li Wei , Tang Fan , Li Xu , Yang Ping
Published: February 2015

MicroRNAs (miRNAs) play a critical role in the development of cancers. However, the role of miRNAs in glioma is still poorly understood. In this study, we demonstrate that microRNA‐10a (miR‐10a) promotes cell migration and invasion by negatively regulating the expression of Eph tyrosine kinase receptor A8 (EphA8). Ectopic expression of EphA8 counteracts the promotion of migration and invasion induced by miR‐10a. We further demonstrate that miR‐10a and EphA8 regulate epithelial–mesenchymal transition (EMT) to affect cell migration and invasion. Collectively, we unveil a branch of the miR‐10a/EphA8 pathway that regulates the progression of glioma.
Human EP2 prostanoid receptors exhibit more constraints to mutations than human DP prostanoid receptors
Authors: Tanimoto Jun , Fujino Hiromichi , Takahashi Hiroki , Murayama Toshihiko
Published: February 2015

Human D‐type prostanoid (DP) and E‐type prostanoid 2 (EP2) receptors are regarded as the most closely related receptors among prostanoid receptors. Although these receptors are generated by tandem duplication, their physiological outputs often oppose one another. In the present study, we extracted mutations occurring in the coding regions of both receptors using the 1000 genome project database and found that EP2 receptors have 8‐fold fewer amino acid mutations. We speculate that EP2 receptors exhibit more constraints to mutations than DP receptors.
Model scenarios for switch‐like mitotic transitions
Authors: Vinod P.K. , Novak Bela
Published: February 2015

To facilitate rapid accumulation of Cdk1‐phosphorylated substrate proteins, the Cdk1 counter‐acting phosphatase, PP2A‐B55 is inhibited during M phase by stoichiometric inhibitors (ENSA and Arpp19). These inhibitors are activated when phosphorylated by Cdk1‐activated Greatwall‐kinase. Recent experiments show that ENSA is dephosphorylated and inactivated by the PP2A‐B55 itself, and acts as an unfair substrate inhibiting PP2A‐B55 activity towards other Cdk1 substrates. Mathematical modelling shows that this mutual antagonism between the phosphatase and its inhibitor is insufficient to explain the switch‐like characteristics of mitotic entry and exit. We show that the feedback regulation of Greatwall activating kinase and/or inactivating phosphatase can explain the abruptness of these cell cycle transitions.
Posting strategically: The consumer as an online media planner
Authors: Chen Yu‐Jen , Kirmani Amna
Published: February 2015

How do consumers choose to post their brand reviews online? Whereas prior research examines what people say online, we investigate where consumers post their brand‐related consumption experience on an online discussion forum. Using the framework of the Persuasion Knowledge Model, we suggest that consumers act as intuitive media planners to assess the extent to which they can reach their specific goals when targeting online audiences. Specifically, we examine the effects of posters' motives, message valence, and audience similarity on posting behavior. We propose and find that persuasion‐motivated consumers focus on whether the message is effective in generating interest and emotion from the audience; therefore, they are more likely to post positive messages on a brand‐general forum, such as a product forum, and negative messages on a brand‐specific forum. In contrast, affiliation‐motivated posters primarily focus on audience similarity, preferring to post on a forum where they perceive the audience as similar to them. Three experiments show the different posting patterns under the two motives and demonstrate the mediating role of message effectiveness under a persuasion motive.
Sea level, paleogeography, and archeology on California's Northern Channel islands
Authors: Reeder-Myers Leslie , Erlandson Jon M. , Muhs Daniel R. , Rick Torben C.
Published: February 2015

Sea-level rise during the late Pleistocene and early Holocene inundated nearshore areas in many parts of the world, producing drastic changes in local ecosystems and obscuring significant portions of the archeological record. Although global forces are at play, the effects of sea-level rise are highly localized due to variability in glacial isostatic adjustment (GIA) effects. Interpretations of coastal paleoecology and archeology require reliable estimates of ancient shorelines that account for GIA effects. Here we build on previous models for California's Northern Channel Islands, producing more accurate late Pleistocene and Holocene paleogeographic reconstructions adjusted for regional GIA variability. This region has contributed significantly to our understanding of early New World coastal foragers. Sea level that was about 80-85 m lower than present at the time of the first known human occupation brought about a landscape and ecology substantially different than today. During the late Pleistocene, large tracts of coastal lowlands were exposed, while a colder, wetter climate and fluctuating marine conditions interacted with rapidly evolving littoral environments. At the close of the Pleistocene and start of the Holocene, people in coastal California faced shrinking land, intertidal, and subtidal zones, with important implications for resource availability and distribution.
Statistical structure of self-sustaining attached eddies in turbulent channel flow
Authors: Hwang Yongyun
Published: February 2015

The linear growth of the spanwise correlation length scale with the distance from the wall in the logarithmic region of wall-bounded turbulent flows has been understood as a reflection of Townsend’s attached eddies. Based on this observation, in the present study, we perform a numerical experiment, which simulates energy-containing motions only at a given spanwise length scale in the logarithmic region, using their self-sustaining nature found recently. The self-sustaining energy-containing motions at each of the spanwise length scales are found to be self-similar with respect to the given spanwise length. Furthermore, their statistical structures are consistent with those of the attached eddies in the original theory, providing direct evidence on the existence of Townsend’s attached eddies. It is shown that a single self-sustaining attached eddy is composed of two distinct elements, one of which is a long streaky motion reaching the near-wall region, and the other is a relatively short vortical structure carrying all the velocity components. For the given spanwise length ${\it\lambda}_{z}$ between ${\it\lambda}_{z}^{+}=100$ and ${\it\lambda}_{z}\simeq 1.5h$, where $h$ is half the height of the channel, the former is found to be self-similar along $y\simeq 0.1{\it\lambda}_{z}$ and ${\it\lambda}_{x}\simeq 10{\it\lambda}_{z}$, while the latter is self-similar along $y\simeq 0.5{\it\lambda}_{z}\sim 0.7{\it\lambda}_{z}$ and ${\it\lambda}_{x}\simeq 2{\it\lambda}_{z}\sim 3{\it\lambda}_{z}$ where $y$ is the wall-normal direction. The scaling suggests that the smallest attached eddy would be a near-wall coherent motion in the form of a streak and quasi-streamwise vortices aligned to that, whereas the largest one would be an outer motion with a very-large-scale motion (VLSM) and large-scale motions (LSMs) aligned to that. The attached eddies in between, the size of which is proportional to their distance from the wall, contribute to the logarithmic region and fill the space caused by the length scale separation. The scaling is also found to yield behaviour consistent with the emergence of $k_{x}^{-1}$ spectra in a number of previous studies. Finally, a further discussion is provided, in particular on Townsend’s inactive motion and several recent theoretical findings.
Centre-manifold reduction of bifurcating flows
Authors: Carini M. , Auteri F. , Giannetti F.
Published: February 2015

In this paper we describe a general and systematic approach to the centre-manifold reduction and normal form computation of flows undergoing complicated bifurcations. The proposed algorithm is based on the theoretical work of Coullet & Spiegel (SIAM J. Appl. Maths, vol. 43(4), 1983, pp. 776–821) and can be used to approximate centre manifolds of arbitrary dimension for large-scale dynamical systems depending on a scalar parameter. Compared with the classical multiple-scale technique frequently employed in hydrodynamic stability, the proposed method can be coded in a rather general way without any need to resort to the introduction and tuning of additional time scales. The method is applied to the dynamical system described by the incompressible Navier–Stokes equations showing that high-order, weakly nonlinear models of bifurcating flows can be derived automatically, even for multiple codimension bifurcations. We first validate the method on the primary Hopf bifurcation of the flow past a circular cylinder and after we illustrate its application to a codimension-two bifurcation arising in the flow past two side-by-side circular cylinders.
Combustion enhancement in a scramjet engine using oxygen enrichment and porous fuel injection
Authors: Capra Bianca R. , Boyce R. R. , Kuhn M. , Hald H.
Published: February 2015

This paper reports on the experimental testing of oxygen-enriched porous fuel injection in a scramjet engine. Fuel was injected via inlet mounted, oxide-based ceramic matrix composite (CMC) injectors on both flow path surfaces that covered a total of 9.2 % of the intake surface area. All experiments were performed at an enthalpy of $3.93{-}4.25\pm 3.2\,\%~\text{MJ}~\text{kg}^{-1}$, flight Mach number 9.2–9.6 and an equivalence ratio of $0.493\pm 3\,\%$. At this condition, the engine was shown to be on the verge of achieving appreciable combustion. Oxygen was then added to the fuel prior to injection such that two distinct enrichment levels were achieved. Combustion was found to increase, by as much as 40 % in terms of combustion-induced pressure rise, over the fuel-only case with increasing oxygen enrichment. Further, the onset of combustion was found to move upstream with increasing levels of oxygen enrichment. Thrust, both uninstalled and specific, and specific impulse were found to be improved with oxygen enrichment. Enhanced fuel–air mixing due to the pre-mixing of oxygen with the fuel together with the porous fuel injection are believed to be the main contributors to the observed enhanced performance of the tested engine.
Interacting vorticity waves as an instability mechanism for magnetohydrodynamic shear instabilities
Authors: Heifetz E. , Mak J. , Nycander J. , Umurhan O. M.
Published: February 2015

The interacting vorticity wave formalism for shear flow instabilities is extended here to the magnetohydrodynamic (MHD) setting, to provide a mechanistic description for stabilising and destabilising shear instabilities by the presence of a background magnetic field. The interpretation relies on local vorticity anomalies inducing a non-local velocity field, resulting in action at a distance. It is shown here that the waves supported by the system are able to propagate vorticity via the Lorentz force, and waves may interact. The existence of instability then rests upon whether the choice of basic state allows for phase locking and constructive interference of the vorticity waves via mutual interaction. To substantiate this claim, we solve the instability problem of two representative basic states, one where a background magnetic field stabilises an unstable flow and the other where the field destabilises a stable flow, and perform relevant analyses to show how this mechanism operates in MHD.
International investment decisions under uncertainty: Contributions of real options theory and future directions
Authors: Song Sangcheol , Makhija Mona , Kim Sung Min
Published: February 2015

We undertake a critical literature review to facilitate academic dialogs regarding decisions under uncertainty in international business settings and highlight the growing focus on international investments as conveyers of real options. Our literature review (1) provides a systematic overview of uncertainty types considered in this literature, real options identified as particular to international investments, and valuation approaches used and (2) highlights key methodological approaches used for testing real options models applied to international investments, and the controversies in this regard. This study draws on the above to shed light on important avenues for future research including (a) the need for more fine-grained and diverse measures of uncertainty in the international context, (b) an emphasis on clarifying the value effects of combinations of real options, and (c) the necessity of further consideration of the costs of options along with the value.
Will Raman meet bacteria on Mars? An overview of the optimal Raman spectroscopic techniques for carotenoid biomarkers detection on mineral backgrounds
Authors: Hooijschuur J.H. , Verkaaik M.F.C. , Davies G.R. , Ariese F.
Published: February 2015

Raman spectroscopy appears to be an ideal technique for the initial detection of biomarkers, molecules that are potentially indicative of life on planetary bodies elsewhere in our solar system. Carotenoids are particularly useful biomarkers as they are used widely across the species, relatively resistant to breakdown and no inorganic source is known. They are used by microorganisms in their cell membranes for protection against UV radiation. In this paper we focus on the detection of carotenoids in microorganisms within a mineral matrix. We compare the Raman signatures of pure compounds with those of laboratory-made mixtures of β-carotene and minerals. Carotenoids covered by 2.5 mm of translucent calcite or 40 mm of transparent halite were detected using a conventional confocal Raman microscope. To improve sensitivity and hence detection levels, Raman measurements were successfully performed under resonant conditions. Raman analysis can be compromised by fluorescence interference. Data are presented to show how the contribution from the fluorescent background in the Raman spectra can be reduced when making use of gated detection in time-resolved Raman spectroscopy. Overall, this study demonstrates some of the potential of Raman spectroscopy as a method for the detection of (past) life signatures during future planetary missions without taking current technical limitations such as instrumental size into account as recent rapid technical developments suggest these limitations will be resolved in time.
Factorial graphical models for dynamic networks
Authors: WIT ERNST , ABBRUZZO ANTONINO
Published: February 2015

Dynamic network models describe many important scientific processes, from cell biology and epidemiology to sociology and finance. Estimating dynamic networks from noisy time series data is a difficult task since the number of components involved in the system is very large. As a result, the number of parameters to be estimated is typically larger than the number of observations. However, a characteristic of many real life networks is that they are sparse. For example, the molecular structure of genes make interactions with other components a highly-structured and, therefore, a sparse process. Until now, the literature has focused on static networks, which lack specific temporal interpretations.

We propose a flexible collection of ANOVA-like dynamic network models, where the user can select specific time dynamics, known presence or absence of links, and a particular autoregressive structure. We use undirected graphical models with block equality constraints on the parameters. This reduces the number of parameters, increases the accuracy of the estimates and makes interpretation of the results more relevant. We illustrate the flexibility of the method on both synthetic and real data.
Natural fluctuations in un-magnetized and magnetized plasmas
Authors: Tolias P. , Ratynskaia S. , Panarese A. , Longo S. , de Angelis U.
Published: February 2015

There are still open issues within the fluctuation theory of plasmas, in view of the difficulty of formulating adequate theoretical approaches and solving the related equations in particular regimes. A promising alternative approach is direct microphysical modeling based on first principles, as successfully applied to neutral rarefied fluids. Within this approach, the equations of motion of a large ensemble of charged particles are solved numerically while correlations are obtained from statistical analysis of the ensemble at different times. As a first step, in this work we validate the data analysis technique adopted in this numerical scheme for the case of an electron ensemble neglecting Coulomb interactions. The simulation results are compared with the analytical theory of ‘natural’ fluctuations for both un-magnetized and magnetized plasmas. For the latter, the derivations for arbitrary average distribution functions are presented.
Identifying high-value areas to strengthen marine conservation in the channels and fjords of the southern Chile ecoregion
Authors: Vila Alejandro R. , Falabella Valeria , Gálvez Mauricio , Farías Aldo , Droguett Daniela , Saavedra Bárbara
Published: February 2015

Although Chile has been establishing marine protected areas since the 1960s, studies to identify representative areas for marine biodiversity conservation at the ecoregional scale are lacking. Using theMarxandecision support tool we conducted a systematic planning process to identify High Conservation Value Areas in the channels and fjords of the southern Chile ecoregion. We involved 74 experts and other stakeholders in identifying conservation features, setting targets and compiling distribution data. Current distributions of 39 features were used inMarxananalyses. In one scenario we locked planning units that contained the Francisco Coloane Marine Protected Area. In a second scenario we also excluded planning units that overlapped with Appropriate Areas for Aquaculture, defined by the Chilean government's coastal zoning process. One-hundred percent of the proposed conservation targets were met in both scenarios. Although the distribution of 12 conservation features overlapped to a certain extent (>10%) with Appropriate Areas for Aquaculture,Marxanidentified conservation solutions avoiding these areas. Our suggested portfolio of High Conservation Value Areas comprises a network of 33 sites, covering 99,432 km2(12% of the ecoregion). These results provide the first science-based roadmap for decision makers and conservationists, and were used by the Chilean government in its coastal zoning process to define priority areas for conservation. Consequently, salmon farming has been excluded from Tierra del Fuego island.
Problems in the Stone Age of South-east Asia Revisited
Authors: Reynolds T. E. G.
Published: February 2015

In the 13 years since ‘Problems in the Stone Age of Southeast Asia’ was published, there has been a number of significant developments. There remains a lack of early cultural material despite the possibility that first occupation of the area may date back as far as 1.8 Myrs. It seems that the first hominins in the region were essentially ‘alithic’ in their adaptation, making the reconstruction of their behaviour extremely difficult. There is also a question as to which hominin was first ‘Out of Africa’ and into Asia and a suggestion that Homo erectus is, in fact, an Asian species that may have migrated west. This has important implications for interpretations of the significance of the so-called ‘Movius Line’. By the time stone tool use does appear regularly in the record, modern humans are present but it is still hard to identify the kinds of directional changes that are associated with the Late Pleistocene elsewhere in the world. The question of when humans were able to exploit tropical forests in the region is also one that recent work explores. The recent discoveries from Flores of stone tools that appear to pre-date the arrival of modern humans, and a possibly associated ‘dwarf’ hominin, Homo floresiensis, all require re-appraisal of the nature of human activity in the region.
From Big Houses to Cult Houses: Early Neolithic Timber Halls in Scotland
Authors: Brophy Kenneth
Published: February 2015

This paper addresses a small group of Neolithic monuments recorded as cropmarks in eastern lowland Scotland that have been termed timber halls, the best known example being the large rectangular building, Balbridie. Three such sites have now been excavated, and all have been shown to date to the early centuries of the Neolithic and to have been largely similar structures; further possible examples in the cropmark record will be assessed, through looking at the use of the term ‘timber hall’ in Scottish archaeology over the past 40 years. The paper will also address a number of sites, mostly known as cropmarks, which have similar dimensions and architectural traits to these timber halls. Excavations, however, have shown them to have a very different form (for instance, probably unroofed), and to date to the latter half of the 4th millennium calBC,several centuries later than the first timber halls. Drawing on excavation results, cropmarks, and evidence from outwith Scotland, this paper will discuss the changing form and function of the Neolithic ‘timber hall’ tradition in Scotland, arguing that roofed ‘big houses’ were later replaced by ceremonial and mortuary ‘cult houses’, drawing on social memory and tradition.
A Collection of Early Upper Palaeolithic Artefacts from Beedings, near Pulborough, West Sussex, and the Context of Similar Finds from the British Isles
Authors: Jacobi Roger , Debenham Nick , Catt John
Published: February 2015

This paper provides a first formal description of a collection of lithic artefacts unearthed during the building of a house called Beedings on a scarp crest near Pulborough in West Sussex.The discovery was probably made in 1900. The collection is very obviously multi-period, but it includes the largest group of Early Upper Palaeolithic artefacts from south-eastern England. Attributed to this time are leaf-points, end-scrapers, and burins. While recent selection has much reduced the collection it also appears to contain contemporary cores and debitage and evidence for the production of bladelets. In a British context this find is unique and in a European perspective it is one of the richest assemblages attributable to the Lincombian–Ranisian–Jerzmanowician technocomplex. The age of this technocomplex is poorly constrained, but in this paper it is argued to belong to the earliest part of the Upper Palaeolithic, starting earlier than the local Aurignacian. The Upper Palaeolithic material from Beedings is interpreted as having come from a hunting camp situated so as to exploit the extensive views across the western Weald.
Families, Prestige Goods, Warriors & Complex Societies: Beaker Groups of the 3rd Millennium calBCAlong the Upper & Middle Danube
Authors: Heyd Volker
Published: February 2015

From the Middle Copper Age in the mid-4th millennium calBC, and throughout the whole Late Copper Age, we observe the emergence of supra-regional, expansionistic ‘cultures’. Originating in south-east Europe, they expanded into central and northern Europe, eventually reaching the west and the margins. Typical of these are the Černavoda III/Boleráz cultures; then, later, the Baden sequence, along with the Globular Amphora Culture adjacent to the northern arc of the Carpathian mountains. The Corded Ware/Single Grave Cultures, and finally the Bell Beaker Culture, follow in a third stage from the first quarter of the 3rd millennium calBC. The latter expand – emerging from the Iberian Peninsula according to current research – towards the east in a fourth stage, reaching Britain and Ireland, Central Europe, and the central Mediterranean by 2500 calBC. It is now common knowledge that this Bell Beaker phenomenon does not represent a homogeneous unit, but splits into at least four supra-regional groupings. Of these, the Central European, or Bell Beaker East Group, is the focus of this study.

The many published and well-dated assemblages along the Danube between southern Germany and western Hungary, and also in the Czech Republic, allow us to pose questions concerning the social organisation of these Beaker societies. Extended families, without visible hierarchies between them, are mirrored in cemeteries as the basic social unit. The settlement pattern seems to consist of single farmsteads, often closely spaced and each inhabited by one of these extended families. As self-sufficient, but flexibly organised and already partly specialised economic units, they demonstrate an equal exchange of information, goods, genes, and social values. Existing fundamental hierarchies within these families are demonstrated, however, by unequal burial customs, in particular the inclusion of prestige objects in some graves, and by some lavishly equipped child burials of both sexes, as well as in the portrayal of some individuals in death as hunters or warriors, buried with archery equipment.

Bell Beaker society displays an intermediate position between ranked and stratified societies, with signs that it was evolving towards simple chiefdoms. However, this stage of social organisation is only fully reached in Central Europe during the second half of the Early Bronze Age, from 2000 calBConwards.
Genuine Diversity? The Broom Biface Assemblage
Authors: Hosfield Robert , Chambers Jennifer
Published: February 2015

The Broom Lower Palaeolithic locality, on the river Axe at the Devon/Dorset border in south-western Britain, yielded an assemblage of at least 1800 Acheulean artefacts between the 1870s and 1940s through gravel quarrying and antiquarian collection. The bifacial material, predominantly produced in chert but including a small flint component, is characterised by considerable typological diversity and a distinctive asymmetrical element. While aspects of the assemblage have been reported before, this paper presents new work on the artefacts of the C.E. Bean collection and the sample from Exeter Museum. The Bean archive indicates that the artefact patterning is not due to fluvial mixing of separate, typologically-discrete, assemblages. Analysis of the artefacts suggests that hominin knapping strategies were not notably constrained by variations in raw material granular quality, but that the typological variability strongly reflects blank form and shape. However, while the influences of blank form and resharpening, including the use of tranchet flaking, partially explain the assemblage's asymmetrical component, a significant proportion of those artefacts cannot be understood in these terms. The existence of local, short-lived manufacturing traditions, perhaps reflecting the idiosyncratic approaches of individual knappers, is argued to best explain the distinctive asymmetrical element of the Broom assemblage. This interpretation is further supported by (i) the geoarchaeological model of assemblage formation, which assigns the majority of the artefacts to a single phase of occupation, and (ii) the OSL ages of the Broom fluvial deposits (predominantly MIS-9 and 8) and the atypical character of the assemblage in relation to other British late Lower Palaeolithic material, which oppose the notion of longer-lived, locally, or regionally-maintained, traditions.
Excavations at PolitikoKokkinorotsos. A Chalcolithic Hunting Station in Cyprus
Authors: Webb Jennifer M. , Frankel David , Croft Paul , McCartney Carole
Published: February 2015

Recent excavations at a small Chalcolithic site in central Cyprus show that it was occupied about 2880–2670 cal BC. Fallow deer form the major component of the substantial faunal sample: both these and other animals were hunted. The chipped stone, too, fits with a model of intensive meat exploitation. The lack of formal architecture supports the general model of a seasonally or intermittently used hunters' village. Plant remains and a limited array of ground stone tools, however, indicate that domesticated plants were processed and consumed, although probably not harvested at the site, while large quantities of pottery also show a wider range of activities. These data and observations can be explained by several models, which emphasise either broad processes and historical developments or more local patterns of varied site-types and activities in different parts of the island or in different ecological zones, providing an important insight into the diversity and complexity of cultural systems in the early 3rd millennium BC.