bluuebunny/crossref_metadata_2025 huggingface dataset:
OPTIMUM GROUNDWATER TABLE DEPTH AND IRRIGATION SCHEDULES FOR CONTROLLING SOIL SALINITY IN CENTRAL IRAQ
Authors: Qureshi Asad Sarwar , Ahmad Waqas , Ahmad Al‐Falahi A.
Published: June 2013

Excessive irrigation and poor drainage conditions are the major factors contributing to rising groundwater tables and soil salinity in the irrigated areas of Central Iraq. Therefore calculations of precise irrigation requirements are necessary to optimize crop production and keep the groundwater table below the root zone to avoid soil salinization. In this study, the soil–water–atmosphere–plant (SWAP) model is used to determine optimal groundwater table depth and irrigation amounts for the study area. SWAP was calibrated using field data from the study area during the wheat and maize season of 2011–2012. The modelling results reveal that under current irrigation practices (600 mm to wheat and 1000 mm to maize), more than 30% water is lost as deep percolation. This causes a rise in the groundwater table and reduction in crop yields. The model simulations suggest that a groundwater table depth of 200 cm together with an irrigation application of 500 mm to wheat and 600 mm to maize will be the best combination to attain optimal yields. Therefore a drainage system in these areas should be installed to maintain groundwater table depth around 200 cm. Maintaining adeeper groundwater table will not be suitable as costs will increase and crop responses negligible. For long‐term sustainability, rehabilitation of existing drainage systems to evacuate excessive salts from the root zone will be imperative. Copyright © 2013 John Wiley & Sons, Ltd.
Migration of CXCR4 gene‐modified bone marrow‐derived mesenchymal stem cells to the acute injured kidney
Authors: Liu Nanmei , Tian Jun , Cheng Jin , Zhang Jinyuan
Published: June 2013

Bone marrow‐derived mesenchymal stem cells (BMSCs) can migrate to the injured kidney after acute kidney injury (AKI) with limited efficiency. This study investigated the effect of CXCR4 overexpression on BMSC migration to the AKI kidney and the possible mechanisms. CXCR4 gene‐modified BMSCs (CXCR4‐BMSCs) and null‐BMSCs were prepared and transplanted into the AKI mice. Blood indicators, histology, expression of stromal cell‐derived factor 1 (SDF‐1), and BMSC migration were investigated. Hypoxia/re‐oxygenation‐pretreated renal tubular epithelial cells (HR‐RTECs) were prepared to generate AKI in vitro. The chemotaxis experiment was performed using the transwell chamber. The phosphorylation of AKT and MAPK in the BMSCs was also investigated. The CXCR4‐BMSCs showed a remarkable expression of CXCR4. The SDF‐1 expression in the AKI renal tissue was increased. CXCR4‐BMSCs transplantation sharply increased the accumulation of BMSCs in the renal tissue, which was consistent with a greater improvement of renal function. The in vitro experiments showed that the migration of BMSCs to the HR‐RTEC culturing chamber was CXCR4‐dependent, and could be fully inhibited by AMD3100, a CXCR4‐specific antagonist. The migration could also be partly blocked by either LY294002 (PI3K inhibitor) or PD98059 (MAPK inhibitor). Phosphorylated Akt and MAPK were increased in the BMSCs co‐cultured with HR‐RTECs and their expression was the highest in the CXCR4‐BMSCs, which could be recovered by AMD3100. Overexpression of CXCR4 gene could enhance BMSC migration to the kidney area after AKI. The SDF‐1/CXCR4 axis via its activation of PI3K/AKT and MAPK in BMSCs could be the possible mechanisms underlying this function. J. Cell. Biochem. 114: 2677–2689, 2013. © 2013 Wiley Periodicals, Inc.
Targeted gene delivery with noncovalent electrostatic conjugates of sgc‐8c aptamer and polyethylenimine
Authors: Shahidi‐Hamedani Nasim , Shier Wayne T. , Moghadam Ariaee Faezeh , Abnous Khalil , Ramezani Mohammad
Published: June 2013

Background

Several strategies have been shown to improve the transfection efficiency of polyethylenimine (PEI) as a nonviral gene delivery vector. In the present study, a nucleic acid aptamer specific for protein tyrosine kinase 7 (PTK7) surface marker, sgc‐8c, was conjugated electrostatically to pre‐formed 10‐kDa PEI/plasmid DNA polyplexes, and the ability of the conjugate to transfer genetic material was evaluated in MOLT‐4 human acute lymphoblastic leukemia T‐cells, which express PTK7 on their surface.

Methods

Polyplexes (plasmid DNA–vector conjugates), prepared using PEI–sgc‐8c conjugate and pCMVLuc as a reporter gene, were characterized in terms of particle size, surface charge and the extent of DNA condensation. Polyplexes were also evaluated for cytotoxicity using the MTS colorimetric assay, as well as for transfection efficiency in MOLT‐4 cells, and compared with the results obtained in U266 cells, which lack cell surface PTK7.

Results

Relative to pDNA/PEI, the size of pDNA/PEI/sgc‐8c aptamer polyplexes increased with decreasing zeta potential. In MOLT‐4 cells, pDNA/PEI/sgc‐8c aptamer polyplexes exhibited an almost six‐ to eight‐fold increase in transfection efficiency compared to that of pDNA/PEI polyplex, indicating that conjugation of sgc‐8c aptamer to pre‐formed 10‐kDa PEI/plasmid DNA polyplexes achieved effective targeting without covalent attachment, whereas receptor‐mediated conducted transfection was confirmed by performing a competitive transfection experiment and a cellular uptake study.

Conclusions

The results of the present study provide an example of the usefulness of a nucleic acid aptamer in the form of noncovalent, electrostatic conjugates as an approach for enhancing the transfection efficiency of a polycation vector such as PEI without significant induced cytotoxicity. Copyright © 2013 John Wiley & Sons, Ltd.
Surface‐enhanced Raman spectra of the neonicotinoid pesticide thiacloprid
Authors: Cañamares Maria Vega , Feis Alessandro
Published: June 2013

Thiacloprid is a widely used pesticide belonging to the neonicotinoid class, which is characterized by a selective activity against insects and a reduced acute toxicity for humans. The importance of the environmental impact of neonicotinoids is being intensively researched, in order to evaluate the danger they pose for useful insects. Physical methods which allow the characterization of neonicotinoids in diluted aqueous solutions are therefore desirable. We present a study of Raman and surface‐enhanced Raman scattering (SERS) spectroscopy on thiacloprid in solid state, in acetone solution, and adsorbed onto silver and gold hydrosols at μM concentration. Density functional theory calculations allow the individualization of the most stable molecular structure, both in gas phase and in solution, and of the corresponding Raman spectra. The vibrational assignments lead to an interpretation of the differences between SERS and ordinary Raman spectra based on the possible interactions between the molecule and the metal surface, the main one involving the iminocyano group. Formation of a charge‐transfer complex is suggested by the dependence of the SERS spectra on the laser excitation wavelength. We evaluate the applicability of SERS spectroscopy to the chemical analysis of thiacloprid comparing SERS with current analytical methods. Copyright © 2013 John Wiley & Sons, Ltd.
Kinetics of Iodous Acid Disproportionation
Authors: Schmitz Guy , Furrow Stanley D.
Published: June 2013

The iodous acid disproportionation is autocatalytic, and it is not easy to measure the rate constant of the step 2IO2H → IO3− + IOH + H+ separately. Hg(II) was used previously to suppress the autocatalytic pathway, but this method presents difficulties discussed in this work. A more effective method is the use of crotonic acid, an effective IOH scavenger. It suppresses side reactions, and a purely second‐order rate law is obtained. The rate constant decreases from 5 to 0.2 M−1 s−1 when the sulfuric acid concentration increases from 0.08 to 0.60 M. The observed decrease could be explained if IO2− reacts faster than IO2H. This may have consequences for the mechanism of the oscillating Bray–Liebhafsky reaction.
Morphological and electrochemical properties of “polyelectrolyte multilayer films” made from polyaniline and ZnO nanoparticles: Deposition as films or as clusters?
Authors: Chen Xiaoxu , Cai Hongyuan , Liang Danwei , Wang Min , Tang Qunwei
Published: June 2013

Deposits made by the alternated deposition of polyaniline (PANI) and ZnO nanoparticles may offer interesting applications as nonvolatile memory devices owing to the specific properties of each constituent. The rectifying ratio of such devices may strongly depend on the PANI/ZnO interface and on the morphology of the (PANI/ZnO)n or (PANI/ZnO)n‐PANI films. In this article we show that even if the morphology of the PEI/PSS‐(PANI/ZnO)n or of the PEI/PSS‐(PANI/ZnO)n‐PANI films seems very heterogeneous on the basis of scanning electron micrographs, the deposits consist of clusters deposited on a continuous film. In addition, the deposits become impermeable to ferrocyanide anions after the deposition of n = 10 alternated deposition cycles, confirming the existence of a continuous and impermeable film below the observed clusters. Such deposits may find interesting properties as a nonvolatile memory device. POLYM. COMPOS. 34:1333–1341, 2013. © 2013 Society of Plastics Engineers
ABIOTIC METHANE ON EARTH
Authors: Etiope Giuseppe , Sherwood Lollar Barbara
Published: June 2013

Over the last 30 years, geochemical research has demonstrated that abiotic methane (CH4), formed by chemical reactions which do not directly involve organic matter, occurs on Earth in several specific geologic environments. It can be produced by either high‐temperature magmatic processes in volcanic and geothermal areas, or via low‐temperature (<100°C) gas‐water‐rock reactions in continental settings, even at shallow depths. The isotopic composition of C and H is a first step in distinguishing abiotic from biotic (including either microbial or thermogenic) CH4. Herein we demonstrate that integrated geochemical diagnostic techniques, based on molecular composition of associated gases, noble gas isotopes, mixing models, and a detailed knowledge of the geologic and hydrogeologic context are necessary to confirm the occurrence of abiotic CH4 in natural gases, which are frequently mixtures of multiple sources. Although it has been traditionally assumed that abiotic CH4 is mainly related to mantle‐derived or magmatic processes, a new generation of data is showing that low‐temperature synthesis related to gas‐water‐rock reactions is more common than previously thought. This paper reviews the major sources of abiotic CH4 and the primary approaches for differentiating abiotic from biotic CH4, including novel potential tools such as clumped isotope geochemistry. A diagnostic approach for differentiation is proposed.
A spectral assessment review of current satellite‐only and combined Earth gravity models
Authors: Tsoulis Dimitrios , Patlakis Konstantinos
Published: June 2013

The realization over the last decade of dedicated gravity field satellite missions enabled the production of a series of new satellite‐only and combined models for the Earth's gravity field. Using different sensors, measurement techniques, and algorithmic procedures, the final product in each case is a set of spherical harmonic coefficients representing the series expansion of the gravitational potential up to a certain maximum degree, depending on the mission characteristics and the range of the available data. The present review performs a detailed quantified analysis of a representative selection of currently available CHAMP (Challenging Minisatellite Payload), GRACE (Gravity Recovery and Climate Experiment), GOCE (Gravity Field and Steady‐State Ocean Circulation Explorer), and combined Earth gravity models. In this comparative analysis, we also include the so‐called topographic/isostatic gravity models that represent the contribution of global digital elevation maps for the topography and ocean bathymetry. Applying a range of available spatial and spectral accuracy and assessment measures, such as correlation per degree and order, smoothing per degree and order, signal‐to‐noise ratio, gain, degree variances, and error degree variances, one gains a quantified “peek” inside the quality of these models spanning over their whole spectrum. The applied error and assessment measures are defined both in an absolute and relative manner with respect to other similar models or some reference Earth gravity models. Furthermore, the nature of the performed analysis (degree‐wise, order‐wise, and cumulative) permits the identification of distinct spectral bandwidths in these models, enables the quantification of some standard features of the observed field, such as its “long wavelength”, “short wavelength”, or “very high frequency part”, and specifies the attenuation of the gravity signal with increasing altitude from the Earth's surface. An examination of the assessment quantities reveals certain bandwidths of these models with characteristic statistical features. A band‐limited synthesis of these bandwidths in the space domain quantifies the corresponding contributions in terms of selected gravity field functionals, including second‐order derivatives at GOCE altitude.
Log‐linear modelling of pairwise interobserver agreement on a categorical scale
Authors: Becker Mark P. , Agresti Alan
Published: June 2013

This article uses log‐linear models to describe pairwise agreement among several raters who classify a sample on a subjective categorical scale. The models describe agreement structure simultaneously for second‐order marginal tables of a multidimensional cross‐classification of ratings. Practical difficulties arise in fitting the models, because models refer to pairwise marginal tables of a very large and sparse table. A standard analysis that treats the marginal tables as independent yields consistent estimates of model parameters, but not of the covariance matrix of the estimates. We estimate the covariance matrix using the jackknife. We apply the models to describe agreement between evaluations made by seven pathologists of carcinoma in situ of the uterine cervix, using a five‐level ordinal scale. Previous analyses showed differences among the pathologists in their pairwise levels of agreement, but we observe near homogeneity in the dependence structure of their ratings.
Mode C flow transition behind a circular cylinder with a near-wake wire disturbance
Authors: Yildirim I. , Rindt C. C. M. , van Steenhoven A. A.
Published: June 2013

The three-dimensional transition of the flow behind a circular cylinder with a near-wake wire disturbance has been investigated experimentally. The asymmetric placement of a wire in the near-wake region of the cylinder causes an unnatural mode of shedding to occur, namely mode C. We performed flow visualization and particle image velocimetry (PIV) experiments to investigate the influence of the wire on various properties of the flow, such as the dynamics of the streamwise secondary vortices. Experiments were performed at the Reynolds number range of Re = 165–300. From these experiments, it can be concluded that mode C structures are formed as secondary streamwise vortices around the primary von Kármán vortices. The spanwise wavelength of those mode C structures is determined to be approximately two cylinder diameters. The presence of the wire also triggered the occurrence of period doubling in the wake. Each new set of mode C structures is out of phase with the previous set, i.e. doubling the shedding period. This period-doubling phenomenon is due to a feedback mechanism between the consecutively shed upper vortices.
Efficacy of the active middle-ear implant in patients with sensorineural hearing loss
Authors: Butler C L , Thavaneswaran P , Lee I H
Published: June 2013

Introduction:

This systematic review aims to advise on the effectiveness of the active middle-ear implant in patients with sensorineural hearing loss, compared with external hearing aids.

Methods:

A systematic search of several electronic databases, including PubMed and Embase, was used to identify relevant studies for inclusion.

Results:

Fourteen comparative studies were included. Nine studies reported on the primary outcome of functional gain: one found that the middle-ear implant was significantly better than external hearing aids (p < 0.001), while another found that external hearing aids were generally significantly better than middle-ear implants (p < 0.05). Six of the seven remaining studies found that middle-ear implants were better than external hearing aids, although generally no clinically significant difference (i.e. ≥10 dB) was seen.

Conclusion:

Generally, the active middle-ear implant appears to be as effective as the external hearing aid in improving hearing outcomes in patients with sensorineural hearing loss.
Prediction plays a key role in language development as well as processing
Authors: Johnson Matt A. , Turk-Browne Nicholas B. , Goldberg Adele E.
Published: June 2013

Although the target article emphasizes the important role of prediction in language use, prediction may well also play a key role in the initial formation of linguistic representations, that is, in language development. We outline the role of prediction in three relevant language-learning domains: transitional probabilities, statistical preemption, and construction learning.
The poor helping the rich: How can incomplete representations monitor complete ones?
Authors: Strijkers Kristof , Runnqvist Elin , Costa Albert , Holcomb Phillip
Published: June 2013

Pickering & Garrod (P&G) propose that inner speech monitoring is subserved by predictions stemming from fast forward modeling. In this commentary, we question this alignment of language prediction with the inner speech monitor. We wonder how the speech monitor can function so efficiently if it is based on incomplete representations.
What does it mean to predict one's own utterances?
Authors: Meyer Antje S. , Hagoort Peter
Published: June 2013

Many authors have recently highlighted the importance of prediction for language comprehension. Pickering & Garrod (P&G) are the first to propose a central role for prediction in language production. This is an intriguing idea, but it is not clear what it means for speakers to predict their own utterances, and how prediction during production can be empirically distinguished from production proper.
Introduction: Electron Backscatter Diffraction Special Section
Authors: Deal Andrew
Published: June 2013

Welcome to the second special section of Microscopy and Microanalysis focused on electron backscatter diffraction (EBSD), which follows the June 2011 issue. The content of the previous special section was provided by participants at EBSD 2010, the second Microanalysis Society (MAS) topical conference dedicated to EBSD in the United States. The present 2013 special section includes work from participants at both EBSD 2012, the third of such topical conferences (held June 19–21, 2012 at Carnegie Mellon University, Pittsburgh, PA), and EMAS 2012, the European Microanalysis Society's 10th Regional Workshop that included three EBSD sessions (held June 17–20 at the Institute for Geosciences and Earth Resources, Padua, Italy).
Removing barriers to trade on environmental goods: an appraisal
Authors: BALINEAU GAËLLE , DE MELO JAIME
Published: June 2013

This paper reviews the extent of reductions in tariffs on environmental goods (EGs) by country participation in the negotiations mandated by a Doha Ministerial Decision in November 2001. Symptomatic of the cleavages across countries throughout the Round, little progress was achieved during the negotiations in defining an approach to a multilateral reduction in protection of EGs. Conflicting interests and differing perceptions of the benefits from increased trade in EGs was reflected in the different approaches proposed by members (request and offer, integrated project, list approach, hybrid approach), and for the few countries (13) that adopted a list approach, there was little overlap across submissions. For all income groups, on average, EGs are less protected than other goods and countries reduced protection by about 50% from initial levels in 1996 leaving little room for further exchange of market access. Difficulties in applying the two complementary conceptions of EGs: (i) ‘goods for environmental management’, and (ii) ‘environmentally preferable products' are reviewed and mentioned as reasons for the lack of progress during the negotiations. Inspection of the submission lists against a ‘core list’ of 26 EGs drawn up by the WTO shows that this ‘core list’ was mostly made up of products in which developed countries had a comparative advantage, and that countries that submitted lists generally avoided including on their lists the most highly protected goods.
A multi-criteria assessment of the production and marketing systems of local mountain food
Authors: Prišenk Jernej , Rozman Črtomir , Pažek Karmen , Turk Jernej , Bohak Zarja , Borec Andreja
Published: June 2013

A multi-criteria model for a qualitative assessment of the production and marketing of local food products (LFP) from mountain areas has been developed by applying the DEX method. The development of the model was carried out and finally applied to ten local food products. The results were given in the form of a qualitative final assessment of both the production and marketing phases. By applying a plus–minus-1 analysis, the influence of various attributes on the final assessment of the LFP was examined. The main bottlenecks in the production and marketing processes were found. A sensitivity test was used to explain the influence of production and marketing on the final assessment. The results give clear directions as to which of the main attributes must be changed/improved or further developed to enable the successful promotion of local food products, which would give rise to an improved economy in mountain areas.
European Initiatives for Selecting Sustainable Flame Retardants
Authors: Beard Adrian
Published: June 2013

Flame retardants, also often referred to as fire retardants, are a diverse group of chemical substances or formulations which are added to plastics, wood or textiles to reduce their propensity to ignite. Since the 1990s, flame retardants have started to raise environmental concerns, because some brominated flame retardants [e.g. polybrominated diphenyl ethers (PBDEs)] were found to form halogenated dioxins and furans in uncontrolled combustion and because the flame retardants were found in various environmental compartments and biota, including humans. This also led to regulatory restrictions in Europe and elsewhere, e.g. the RoHS (European Directive on the Restriction of certain Hazardous Substances in Electric and Electronic Equipment, 2011/65/EU) and WEEE (European Directive on Waste of Electric and Electronic Equipment, 2012/19/EU) legislation. A number of flame retardant producers have responded to these concerns and formed the industry group pinfa (Phosphorus, Inorganic and Nitrogen Flame Retardants Association) in order to develop and promote more environmentally compatible products, focussing on non‐halogenated alternatives. This group has successfully engaged in European research initiatives for sustainable flame retardants and also alternatives assessments by the GreenScreen™ methodology or the US Environmental Protection Agency (EPA) design for environment projects. Other European drivers and activities towards the sustainability of flame retardants are also presented in this chapter.
A Collaborative Industry and University Alternative Assessment of Plasticizers for Wire and Cable
Authors: Morose Gregory , Becker Monica
Published: June 2013

There is increasing regulatory and market pressure on companies to eliminate known chemicals of concern from their products. These companies can face significant challenges in identifying alternatives that are safer and effective. Switching to a new chemical can cost up to millions of dollars and no company wants to switch to a new chemical that later becomes a regulatory target. To assist these companies, the Green Chemistry and Commerce Council (GC3) launched a project in 2010 to develop and pilot a new model for companies and universities to evaluate collaboratively safer alternatives, with the aim of yielding more robust and cost‐effective results through pooling of knowledge and funding for evaluations. The pilot focused on alternatives to toxic plasticizers in PVC and non‐PVC wire and cable applications. The project workplan included assessing the relative hazard of the alternatives using the GreenScreen™, and also technical performance and cost. Chemical manufacturers, plastics compounders, original equipment manufacturers (OEMs), a retailer and the University of Massachusetts Lowell successfully collaborated to assess nine alternative plasticizers and created a group process that can be repeated for other chemicals and applications. This chapter describes the process developed and lessons learned, including strategies used to assess plasticizers with proprietary ingredients.
Kinetic mechanism of the dimeric ATP sulfurylase from plants
Authors: Ravilious Geoffrey E. , Herrmann Jonathan , Goo Lee Soon , Westfall Corey S. , Jez Joseph M.
Published: June 2013

In plants, sulfur must be obtained from the environment and assimilated into usable forms for metabolism. ATP sulfurylase catalyses the thermodynamically unfavourable formation of a mixed phosphosulfate anhydride in APS (adenosine 5′-phosphosulfate) from ATP and sulfate as the first committed step of sulfur assimilation in plants. In contrast to the multi-functional, allosterically regulated ATP sulfurylases from bacteria, fungi and mammals, the plant enzyme functions as a mono-functional, non-allosteric homodimer. Owing to these differences, here we examine the kinetic mechanism of soybean ATP sulfurylase [GmATPS1 (Glycine max (soybean) ATP sulfurylase isoform 1)]. For the forward reaction (APS synthesis), initial velocity methods indicate a single-displacement mechanism. Dead-end inhibition studies with chlorate showed competitive inhibition versus sulfate and non-competitive inhibition versus APS. Initial velocity studies of the reverse reaction (ATP synthesis) demonstrate a sequential mechanism with global fitting analysis suggesting an ordered binding of substrates. ITC (isothermal titration calorimetry) showed tight binding of APS to GmATPS1. In contrast, binding of PPi (pyrophosphate) to GmATPS1 was not detected, although titration of the E•APS complex with PPi in the absence of magnesium displayed ternary complex formation. These results suggest a kinetic mechanism in which ATP and APS are the first substrates bound in the forward and reverse reactions, respectively.
Stochastic dynamics of penetrable rods in one dimension: Occupied volume and spatial order
Authors: Craven Galen T. , Popov Alexander V. , Hernandez Rigoberto
Published: June 2013

The occupied volume of a penetrable hard rod (HR) system in one dimension is probed through the use of molecular dynamics simulations. In these dynamical simulations, collisions between penetrable rods are governed by a stochastic penetration algorithm (SPA), which allows for rods to either interpenetrate with a probability δ, or collide elastically otherwise. The limiting values of this parameter, δ = 0 and δ = 1, correspond to the HR and the ideal limits, respectively. At intermediate values, 0 < δ < 1, mixing of mutually exclusive and independent events is observed, making prediction of the occupied volume nontrivial. At high hard core volume fractions ϕ0, the occupied volume expression derived by Rikvold and Stell [J. Chem. Phys. 82, 1014 (1985)]10.1063/1.448966 for permeable systems does not accurately predict the occupied volume measured from the SPA simulations. Multi-body effects contribute significantly to the pair correlation function g2(r) and the simplification by Rikvold and Stell that g2(r) = δ in the penetrative region is observed to be inaccurate for the SPA model. We find that an integral over the penetrative region of g2(r) is the principal quantity that describes the particle overlap ratios corresponding to the observed penetration probabilities. Analytic formulas are developed to predict the occupied volume of mixed systems and agreement is observed between these theoretical predictions and the results measured from simulation.
An experimental study of highly transient squeeze-film flows
Authors: Krassnokutski A. , Moss E. A. , Skews B. W.
Published: June 2013

The aim of this work was to extend a previous investigation of the flow between two parallel disks (one of which was stationary) that have been subjected to a constant energy impact arising from a falling mass onto the upper disk assembly. Whereas the previous work considered the measurement of centreline pressures and distance between the plates only, for a single case, the current work in addition entailed monitoring of pressures at 45% and 90% of disk radius, under 28 combinations of drop height (100 to 1000 mm), drop mass (10 to 55 kg), and initial disk separation (3 to 10 mm), each with 5 repeat tests. Over the duration of the phenomenon (about 3.5 to 10 ms), four basic features were identified: (1) during initial impact under the dominance of temporal inertia, a preliminary pressure spike with peak pressures occurring at a displacement change of less than 0.25 mm from the initial disk separation; (2) an intermediate region with lower pressures; (3) pressure changes arising from a succession of elastic momentum exchanges (bounces) between the colliding masses; and (4) the final largest pressure spike towards the end of the phenomenon, where viscous effects dominate. Regions (1) and (4) became merged for smaller values of initial disk separation, with region (2) being obscured. A previously developed quasi-steady linear (QSL) model conformed satisfactorily with pressures measured at the centre of the lower disk; however, substantial deviations from radially parabolic pressure distributions were encountered over a range of operating parameters during the preliminary pressure phenomenon, unexpected because they implicitly conflict with the generally accepted concept of parallel flows and radially self-similar velocity profiles in such systems. Measurements of maximum pressures encountered during the preliminary and final pressure events agreed satisfactorily, both with the QSL model and with a simple but effective scaling analysis.
Wall forces on a sphere in a rotating liquid-filled cylinder
Authors: Tagawa Yoshiyuki , van der Molen Jarich , van Wijngaarden Leen , Sun Chao
Published: June 2013

We experimentally study the behavior of a particle slightly denser than the surrounding liquid in solid body rotating flow. Earlier work revealed that a heavy particle has an unstable equilibrium point in unbounded rotating flows [G. O. Roberts, D. M Kornfeld, and W. W Fowlis, J. Fluid Mech. 229, 555–567 (1991)10.1017/S0022112091003166]. In the confinement of the rotational flow by a cylindrical wall a heavy sphere with density 1.05 g/cm3 describes an orbital motion in our experiments. This is due to the effect of the wall near the sphere, i.e., a repulsive force (FW). We model FW on the sphere as a function of the distance from the wall (L): FW∝L−4 as proposed by Takemura et al. [J. Fluid Mech. 495, 235–253 (2003)10.1017/S0022112003006232]. Remarkably, the path evaluated from the model including FW reproduces the experimentally measured trajectory. In addition during an orbital motion the particle does not spin around its axis, and we provide a possible explanation for this phenomenon.
Effects of uniaxial pressure on polar whispering gallery modes in microspheres
Authors: Wagner H. P. , Schmitzer H. , Lutti J. , Borri P. , Langbein W.
Published: June 2013

We investigate the detuning of whispering gallery modes (WGMs) in solid polystyrene microspheres (PM) as a function of axisymmetric stress applied to two antipodal points of the microsphere we call poles. We specifically investigate WGMs passing close to these poles, so-called polar WGMs. The applied uniaxial pressure reduces the geometrical circumference of the PM but also increases locally the refractive index at the flattened poles. Our experiments show that the WGMs shift to higher frequencies with increasing pressure and that the magnitude of the strain-induced shift depends on the radial mode number n. Furthermore an energy splitting between azimuthal modes linearly increasing with the pressure is observed. A theoretical model based on a classical ray optics approach is presented which reproduces the main results of our experimental observations.
Numerical investigation on the influence factors of the electrical properties of carbon nanotubes-filled composites
Authors: De Vivo B. , Lamberti P. , Spinelli G. , Tucci V.
Published: June 2013

In order to predict the electrical properties of carbon nanotubes-filled composites, a three-dimensional (3D) numerical model is proposed. A random distribution of impenetrable conducting cylinders inside a cubic insulating matrix models the morphology of the considered material. The variation of the macroscopic electrical performances of the simulated structures is estimated through a suitable 3D resistance and capacitance network associated with the different percolating paths. The introduction in the model of the capacitive effects exhibited by the material, usually not considered in other simulation approaches, allows also a significant analysis in the frequency domain. The electron tunneling effect between conducting structures, determinant in the polymer nanocomposites, is also accurately taken into account to study the composite properties. The obtained results are in good agreement with theoretical predictions and experimental data suggesting that the proposed model can properly estimate different effects upon the electrical properties providing useful hints for the optimization of nanocomposites.
Terahertz rectification by periodic two-dimensional electron plasma
Authors: Popov V. V.
Published: June 2013

The physics of terahertz rectification by periodic two-dimensional electron plasma is discussed. Two different effects yielding terahertz rectification are studied: the plasmonic drag and plasmonic ratchet. Ultrahigh responsivity of terahertz rectification by periodic two-dimensional electron plasma in semiconductor heterostructures and graphene is predicted.
Ligament coarsening in nanoporous gold: Insights from positron annihilation study
Authors: Viswanath R. N. , Chirayath V. A. , Rajaraman R. , Amarendra G. , Sundar C. S.
Published: June 2013

Positron lifetime experiments, coupled with scanning electron microscopy studies, have been used to follow the coarsening of the ligaments of nanoporous Au (np-Au), prepared by electrochemical dealloying of Ag75Au25. Positron lifetime measurements in the as-prepared np-Au indicate two lifetime components, identified with annihilation at vacancies within the ligaments and at the ligament-pore interface. The variation of these lifetime parameters with annealing temperature indicates distinct changes that correlate the migration of vacancies to the growth of ligaments. The lifetime component, corresponding to the annihilation at the ligament-pore interface, shows signature of ligament surface instability.
Standoff alpha radiation detection via excited state absorption of air
Authors: Yao Jimmy , Brenizer Jack , Hui Rongqing , Yin Stuart (Shizhuo)
Published: June 2013

A standoff alpha radiation detection technique based on the physical mechanism of excited state absorption of air molecules was explored and is presented in this paper. Instead of directly detecting the radiation via measuring the intensity of radiation induced air fluorescence, the radiation is detected via the excited state absorption of alpha radiation excited/ionized air molecules. Both theoretical analyses and experimental verifications were conducted. The experimental results confirmed that the radiation could be detected via excited state absorption of radiation excited/ionized air molecules at a 10 m standoff distance, which was consistent with the theoretical analyses.
Using nanopillars of silicon oxide as a versatile platform for visualizing a selective immunosorbent
Authors: Chen Jem-Kun , Zhou Gang-Yan , Huang Chih-Feng , Ko Fu-Hsiang
Published: June 2013

In this study, we fabricated nanopillar arrays of silicon oxide for use as two-dimensional periodic relief gratings (2DPRGs) on Si surfaces. We deposited antibodies onto the pillar surfaces of 2DPRGs modified with protein G to obtain optical detectors that were specific for the targeted antigen; the antigen units that filled the spaces between the nanopillars of the 2DPRG lead to a dramatic change in the pillar scale. The effective refractive index (neff) of the 2DPRGs was related to the pillar scale of the 2DPRG; after coupling of the antigen, a color change from pure green to orange was observable.
‘The Futurist mountains’: Filippo Tommaso Marinetti's experiences of mountain combat in the First World War
Authors: Daly Selena
Published: June 2013

Filippo Tommaso Marinetti's first experience of active combat was as a member of the Lombard Battalion of Volunteer Cyclists and Motorists in the autumn of 1915, when he fought in the mountains of Trentino at the border of Italy and Austria-Hungary. This article examines his experience of mountain combat and how he communicated aspects of it both to specialist, Futurist audiences and to the general public and soldiers, through newspaper articles, manifestos, ‘words-in-freedom’ drawings, speeches and essays written between 1915 and 1917. Marinetti's aim in all of these wartime writings was to gain maximum support for the Futurist movement. Thus, he adapted his views to suit his audience, at times highlighting the superiority of the Futurist volunteers over the Alpine soldiers and at others seeking to distance Futurism from middle-class intellectualism in order to appeal to the ordinary soldier. Marinetti interpreted the war's relationship with the natural environment through an exclusively Futurist lens. He sought to ‘futurise’ the Alpine landscape in an effort to reconcile the urban and technophilic philosophy of his movement with the realities of combat in the isolated, rural and primitive mountains of Trentino.
Nation-state global city tensions in social policy: the case of Mexico City's rising social city-zenship
Authors: Hudson John , Medrano Anahely
Published: June 2013

Comparative analyses of welfare systems have largely proceeded on the basis that coherent nation-states exist. This assumption was always problematic – as many theorists have acknowledged – but globalisation processes have added a further dimension to this debate, not least because of the increasing power of global cities that act as coordinating hubs for the global economy. Although residing in nation-states, these cities have a special status flowing from their central role in the global economy with often rather different economic, demographic and social contexts. While there is growing literature on global cities, what the rise of these cities means for social policy and for welfare states remains an underexplored issue. Here we outline some key issues the rise of global cities presents for welfare states before proceeding to illustrate both theoretical and practical issues we highlight through a case study of Mexico City.
Business, as usual: the policy priorities of the World Bank's discourses on youth unemployment, and the global financial crisis
Authors: Fergusson Ross , Yeates Nicola
Published: June 2013

This article undertakes a detailed analysis of the formative role of the World Bank in the framing of youth unemployment. It charts the World Bank's emergence as a powerful political actor in this policy field and identifies the ideational content of its policy discourses on the causes of youth unemployment and responses to it. Four principal themes are identified: skills deficits; wage regulation; the “demographication” of explanations for burgeoning youth unemployment; and connections between youth unemployment, criminal activity and social disorder. The discussion highlights significant evidence of neo-liberal continuity and reinvention in World Bank discourses as its normative and ideational frameworks are extended to new terrains of analysis in ways that infer links between youth unemployment and individual deficits of the unemployed.
John Briggs: A closer look at HIV and coated vesicles
Authors: Sedwick Caitlin
Published: June 2013

Briggs studies the organization of viral and cellular coat proteins using cryo-electron microscopy.
Contribution of the KCa3.1 channel–calmodulin interactions to the regulation of the KCa3.1 gating process
Authors: Morales Patricia , Garneau Line , Klein Hélène , Lavoie Marie-France , Parent Lucie , Sauvé Rémy
Published: June 2013

The Ca2+-activated potassium channel of intermediate conductance, KCa3.1, is now emerging as a therapeutic target for a large variety of health disorders. The Ca2+ sensitivity of KCa3.1 is conferred by the Ca2+-binding protein calmodulin (CaM), with the CaM C-lobe constitutively bound to an intracellular domain of the channel C terminus. It was proposed on the basis of the crystal structure obtained for the C-terminal region of the rat KCa2.2 channel (rSK2) with CaM that the binding of Ca2+ to the CaM N-lobe results in CaM interlocking the C-terminal regions of two adjacent KCa3.1 subunits, leading to the formation of a dimeric structure. A study was thus undertaken to identify residues of the CaM N-lobe–KCa3.1 complex that either contribute to the channel activation process or control the channel open probability at saturating Ca2+ (Pomax). A structural homology model of the KCa3.1–CaM complex was first generated using as template the crystal structure of the C-terminal region of the rat KCa2.2 channel with CaM. This model was confirmed by cross-bridging residues R362 of KCa3.1 and K75 of CaM. Patch-clamp experiments were next performed, demonstrating that the solvation energy of the residue at position 367 in KCa3.1 is a key determinant to the channel Pomax and deactivation time toff. Mutations of residues M368 and Q364 predicted to form anchoring points for CaM binding to KCa3.1 had little impact on either toff or Pomax. Finally, our results show that channel activation depends on electrostatic interactions involving the charged residues R362 and E363, added to a nonpolar energy contribution coming from M368. We conclude that electrostatic interactions involving residues R362 and E363 and hydrophobic effects at M368 play a prominent role in KCa3.1 activation, whereas hydrophobic interactions at S367 are determinant to the stability of the CaM–KCa3.1 complex throughout gating.
Decomposer communities in human‐impacted streams: species dominance rather than richness affects leaf decomposition
Authors: Tolkkinen Mikko , Mykrä Heikki , Markkola Anna‐Mari , Aisala Heidi , Vuori Kari‐Matti , Lumme Jaakko , Pirttilä Anna Maria , Muotka Timo
Published: June 2013

There is compelling evidence that anthropogenic disturbance can decrease biodiversity and impair ecological functioning. A major challenge to biodiversity–ecosystem function research is to disentangle the effects of biodiversity loss on ecosystem functions from the direct effects of human disturbance.

We studied the influence of human disturbance (acidification and eutrophication) and a natural stressor (lowpHdue to bedrock geology) on leaf‐shredding macroinvertebrates, fungal decomposers and leaf decomposition rates in boreal streams. We used pyrosequencing techniques to determine fungal richness and assemblage structure.

Decomposition rates were higher in anthropogenically disturbed than in circumneutral reference or naturally acidic sites, but did not differ between the latter two groups. Macroinvertebrate richness was higher in circumneutral than in human‐impacted or naturally acidic sites, and shredder evenness was highest in circumneutral sites. Fungal evenness was also lower in human‐disturbed than in reference sites, whereas fungal richness did not vary among site groups.

Decomposition rate in fine‐mesh bags was related positively to current velocity and fungal dominance, while in coarse‐mesh bags, it was related positively to total phosphorus. In anthropogenically disturbed streams, the effects of lowpHwere overridden by eutrophication, and increased decomposition rates resulted from disturbance‐induced increase in species dominance rather than richness. Furthermore, decomposition rates were positively correlated with abundances of dominant taxa, suggesting that ecosystem processes may be driven by a few key species.

Synthesis and applications. Our results suggest that leaf decomposition rates are insensitive to natural background variation, supporting the use of decomposition assays, preferably accompanied by molecular analysis of fungal assemblages, to assess stream ecosystem health. Instead of focusing solely on diversity, however, more emphasis should be placed at changes in dominance patterns, particularly if management aims are to improve stream ecosystem functioning.
Evidence for scale‐ and disturbance‐dependent trait assembly patterns in dry semi‐natural grasslands
Authors: de Bello Francesco , Vandewalle Marie , Reitalu Triin , Lepš Jan , Prentice Honor C. , Lavorel Sandra , Sykes Martin T.
Published: June 2013

The mechanisms driving nonrandom assembly patterns in plant communities have long been of interest in ecological research. Competing ecological theories predict that coexisting species may either be more functionally dissimilar than expected by chance (with functional ‘divergence’ mainly reflecting niche differentiation) or be functionally more similar than expected (with functional ‘convergence’ reflecting either the outcome of environmental filtering or weaker‐competitor exclusion effects). Assembly patterns are usually assessed at a single scale and disturbance regime, whereas considering different spatial scales and disturbance regimes may clarify the underlying assembly mechanisms.

 We tested the prediction that convergence and divergence are scale‐ and disturbance‐ dependent in grazed and abandoned species‐rich dry grasslands within a 22 km2 landscape in south‐eastern Sweden. Convergence and divergence were tested for plant species' traits and phylogenetic relationships at three nested spatial scales: within 412 plots (50 × 50 cm, divided into 10 × 10 cm subplots), within 117 grassland patches (from 0.02 to 11.63 ha) and within the whole landscape (across patches).

 At the finest scale (10 × 10 cm subplots within plots), coexisting species were more different than expected by chance (divergence), both functionally and phylogenetically, suggesting niche differentiation. At the intermediate scale (50 × 50 cm plots within patches), coexisting species showed convergence, suggesting environmental filtering. No significant deviations from random expectations were detected at the broadest scale (patches within the 22 km2 landscape) – suggesting the prevalence of dispersal limitation at this scale. The fact that nonrandom patterns were particularly evident under grazed conditions is consistent with the prediction that assembly patterns are disturbance dependent.

 Synthesis. This study shows that multiple trait‐based assembly processes operate simultaneously in species‐rich communities, across spatial scales and disturbance regimes. The results support earlier theoretical predictions that divergence between coexisting species may be an important driver of community assembly, particularly at finer spatial scales, where species compete for the same local resources. In contrast, environmental filtering is expected at broader spatial scales, where species growing in particular environmental conditions share traits that are adaptive under those conditions. Within given habitat types, dispersal limitation may, however, override environmental filtering at increasing spatial scales of observation.