bluuebunny/crossref_metadata_2025 huggingface dataset:
Global nuclear industry views: challenges arising from the evolution of the optimisation principle in radiological protection
Authors: Saint-Pierre S.
Published: September 2012

Over the last few decades, the steady progress achieved in reducing planned exposures of both workers and the public has been admirable in the nuclear sector. However, the disproportionate focus on tiny public exposures and radioactive discharges associated with normal operations came at a high price, and the quasi-denial of a risk of major accident and related weaknesses in emergency preparedness and response came at an even higher price. Fukushima has unfortunately taught us that radiological protection (RP) for emergency and post-emergency situations can be much more than a simple evacuation that lasts 24–48 h, with people returning safely to their homes soon afterwards. On optimisation of emergency and post-emergency exposures, the only ‘show in town’ in terms of international RP policy improvements has been the issuance of the 2007 Recommendations of the International Commission on Radiological Protection (ICRP). However, no matter how genuine these improvements are, they have not been ‘road tested’ on the practical reality of severe accidents. Post-Fukushima, there is a compelling case to review the practical adequacy of key RP notions such as optimisation, evacuation, sheltering, and reference levels for workers and the public, and to amend these notions with a view to making the international RP system more useful in the event of a severe accident. On optimisation of planned exposures, the reality is that, nowadays, margins for further reductions of public doses in the nuclear sector are very small, and the smaller the dose, the greater the extra effort needed to reduce the dose further. If sufficient caution is not exercised in the use of RP notions such as dose constraints, there is a real risk of challenging nuclear power technologies beyond safety reasons. For nuclear new build, it is the optimisation of key operational parameters of nuclear power technologies (not RP) that is of paramount importance to improve their overall efficiency. In pursuing further improvements in the international RP system, it should be clearly borne in mind that the system is generally based on protection against the risk of cancer and hereditary diseases. The system also protects against deterministic non-cancer effects on tissues and organs. In seeking refinements of such protective notions, ICRP is invited to pay increased attention to the fact that a continued balance must be struck between beneficial activities that cause exposures and protection. The global nuclear industry is committed to help overcome these key RP issues as part of the RP community's upcoming international deliberations towards a more efficient international RP system.
Indium 111 Diethylenetriamine Pentaacetic Acid Scintigraphy in the Identification and Management of Intrathecal Pump Malfunction
Authors: Yowtak June , Cato Kelsie , Williams Hadyn , Salazar Pamela , Macomson Samuel , Sekul Elizabeth , Vender John
Published: September 2012

Background

Intrathecal drug‐delivery systems have become widely used tools in the management of refractory chronic pain and spasticity. Because increasing numbers of patients are using these systems, rehabilitation specialists frequently are the initial care providers who identify clinical signs and symptoms indicating possible complications relating to the implanted system. Identification of a pump malfunction often presents a diagnostic challenge. Distinguishing among progression of disease, new organic problems, and/or drug‐device complications is critical. The use of nuclear medicine indium 111 diethylenetriamine pentaacetic acid (DTPA) studies represents a highly effective, straightforward, minimally invasive way to assess implant function and drug distribution.

Objective

To identify patients with suspected intrathecal pump malfunction and to determine whether the use of indium 111 DTPA is effective in identifying the source of failure.

Design

A retrospective review was performed from 2011 to 2012.

Setting

The study was performed at Georgia Health Sciences University.

Patients

The 23 selected patients had implanted devices for either spasticity or pain and were experiencing symptoms of a possible pump malfunction despite normal radiographic imaging. Twenty‐four scintigraphic studies were performed, with malfunction documented in 19 patients.

Methods

A standard refill technique was used to inject 0.3 mL of indium 111 DTPA into the pump reservoir. Radionuclide images were reviewed at varying time points up to 48 hours after injection. The extent of radionuclide progression from the pump reservoir to the intrathecal space was evaluated. In cases in which a problem with the implant was identified, correlation with operative findings is described.

Results

Normal results of studies ultimately correlated with other clinical issues and confirmed an alternative etiology for the clinical changes noted. In studies with abnormal results, several patterns of failure were identified: restriction of the radionuclide to the pump reservoir, extravasations of tracer into the pump subcutaneous pocket, failure of the tracer to migrate from the subcutaneous catheter to the intrathecal space, and pooling of the tracer in the subcutaneous tissues. In all cases, surgical findings confirmed the suspected mechanism of malfunction as determined by the study.

Conclusions

Indium 111 DTPA scintigraphy is a safe, straightforward way to identify and characterize clinical changes associated with intrathecal drug‐delivery systems and to guide appropriate and clinical surgical management.
Vibration Platform Training in Women at Risk for Symptomatic Knee Osteoarthritis
Authors: Segal Neil A. , Glass Natalie A. , Shakoor Najia , Wallace Robert
Published: September 2012

Objective

To determine whether a platform exercise program with vibration is more effective than platform exercise alone for improving lower limb muscle strength and power in women ages 45 to 60 with risk factors for knee osteoarthritis (OA).

Design

Randomized, controlled study.

Setting

Academic center.

Participants

A total of 48 women ages 45‐60 years with risk factors for knee OA (a history of knee injury or surgery or body mass index ≥25 kg/m2).

Interventions

Subjects were randomly assigned to a twice‐weekly lower limb exercise program (quarter squat, posterolateral leg lifts, calf raises, step‐ups, and lunges) on either a vertically vibrating platform (35 Hz, 2 mm) or a nonvibrating platform.

Main Outcome Measurements

Change in isokinetic quadriceps strength, leg press power, and stair climb power by 12 weeks.

Results

A total of 39 of 48 enrolled participants completed the study (26 vibration and 13 control exercise). Nine participants discontinued the study after randomization mainly because of a lack of time. No intergroup differences in age, body mass index, or activity level existed. Isokinetic knee extensor strength did not significantly improve in either group. Leg press power improved by 92.0 ± 69.7 W in the vibration group (P < .0001) and 58.2 ± 96.2 W in the control group (P = .0499) but did not differ between groups (P = .2262). Stair climb power improved by 53.4 ± 64.7 W in the vibration group (P = .0004) and 55.7 ± 83.3 W in the control group (P = .0329) but did not differ between groups (P = .9272).

Conclusions

Whole body vibration platforms have been marketed for increasing strength and power. In this group of asymptomatic middle‐aged women with risk factors for knee OA, the addition of vibration to a 12‐week exercise program did not result in significantly greater improvement in lower limb strength or power than did participation in the exercise program without vibration.
Intestinal helminth fauna of the South American sea lion Otaria flavescens and fur seal Arctocephalus australis from northern Patagonia, Argentina
Authors: Hernández-Orts J.S. , Montero F.E. , Juan- García A. , García N.A. , Crespo E.A. , Raga J.A. , Aznar F.J.
Published: September 2012

We report on the intestinal helminth fauna of 56 South American sea lions, Otaria flavescens, and 5 South American fur seals, Arctocephalus australis, from northern Patagonia, Argentina. A total of 97,325 helminth specimens were collected from sea lions. Gravid individuals were represented by 6 species of parasites: 1 digenean (Ascocotyle (Ascocotyle) patagoniensis), 1 cestode (Diphyllobothrium spp.), 3 nematodes (Uncinaria hamiltoni, Contracaecum ogmorhini s.s., Pseudoterranova cattani) and 1 acanthocephalan (Corynosoma australe). In addition, third-stage larvae of 2 nematodes (Contracaecum sp. and Anisakis sp. type I) and 3 juvenile acanthocephalans (Andracantha sp., Profilicollis chasmagnathi and Corynosoma cetaceum) were also collected. Andracantha sp., C. ogmorhini s.s. and P.chasmagnathi represent new host records. A total of 1516 helminth specimens were collected from fur seals. Gravid individuals were represented by three species of parasites, namely, Diphyllobothrium spp., C. ogmorhini s.s. and C. australe. In addition, larvae of Contracaecum sp. and P. cattani, juveniles of C. cetaceum and immature cestodes (Tetrabothriidae gen. sp.) were also collected. Corynosoma australe was the most prevalent and abundant parasite in both hosts, accounting for >90% of all specimens. Sea lions and furs seals from northern Patagonia harbour the intestinal helminth communities that could be predicted for otariids, i.e. the combination of species of the genera Corynosoma, Diphyllobothrium, Pseudoterranova, Contracaecum and, in pups, Uncinaria. Additionally, both species of otariid are apparently unsuitable hosts (i.e. non-hosts) for as many as five parasite taxa. The inclusion or exclusion of these species affects estimation of species richness at both component community (11 versus 6 species in sea lions; 7 versus 3 species in fur seals) and infracommunity (mean: 3.1 versus 2.6 in sea lions; 2.2 versus 1.7 species) levels. Information about the reproductive status of helminth species is often lacking in parasitological surveys on otariids and other marine vertebrates, but it is of significance to improve precision in parascript studies or ecological meta-analyses.
Insights from the evaluation of a provincial healthy eating strategy in Nova Scotia, Canada
Authors: Sim S Meaghan , Kirk Sara FL
Published: September 2012

Objective

Healthy Eating Nova Scotia represents the first provincial comprehensive healthy eating strategy in Canada and a strategy that is framed within a population-health model. Five years after strategy launch, our objective was to evaluate Healthy Eating Nova Scotia to determine perceptions of strategy implementation and strategy outputs. The focus of the current paper is on the findings of this evaluation.

Design

We conducted an evaluation of the strategy through three activities that included a document review, survey of key stakeholders and in-depth interviews with key strategy informants. The findings from each of the activities were integrated to determine what has worked well with strategy implementation, what could be improved and what outputs have resulted.

Setting

The evaluation was conducted in the Canadian province of Nova Scotia.

Participants

Participants for this evaluation included survey respondents (n 120) and key informants (n 16). A total of 156 documents were also reviewed.

Results

Significant investments have been made towards inter-sectoral partnerships and resourcing that has provided the necessary leadership and momentum for the strategy. Policy development has been leveraged through the strategy primarily in the health and education sectors and is perceived as a visible success. Clarity of human resource roles and funding within the context of a provincial strategy may be beneficial for continued strategy implementation, as is expansion of policy development.

Conclusions

Known to be the first evaluation of its kind, these findings and related considerations will be of interest to policy makers developing and implementing similar strategies in their own jurisdictions.
‘Yo lo vi’. Goya witnessing the disasters of war: an appeal to the sentiment of humanity
Authors: Bouvier Paul
Published: September 2012

Editor's Note

The humanitarian mission maintains its ultimate objective of preventing and alleviating human suffering in situations of extreme crisis. In a different vein from the main subject of this edition- the future of humanitarian action – and using the power of images, Paul Bouvier, ICRC Senior Medical Advisor, brings us back exactly two centuries, to the ‘Peninsular War’ between French, Spanish and British, among the fiercest of the Napoleonic Wars.

The artist Francisco de Goya produced a series of etched plates known as The Disasters of War, which offered a hitherto uncommon view of war. By showing the horror and devastation of armed violence, the resulting dehumanization, and the distress and suffering of the victims, he denounced the consequences of war and famine and the ensuing political repression. Goya's lucid, compassionate, yet uncompromising depictions of war and its consequences are not only unique but also highly relevant today. His work is also an outcry and a plea for acts of humanity in the turmoil of armed violence, and anticipates the initiative that Henry Dunant would be prompted to take sixty years later, in Solferino. In a way, Goya announced Dunant.

Walking us through a selection of Goya's sketches, Paul Bouvier looks at victims, perpetrators, and eye-witnesses, and discusses how these images relate to the contemporary experience of humanitarian workers faced with the extreme violence of war. The author decrypts Goya’s sketches and relates them to the essence of humanitarian action as a response to human suffering.
Stochastic simulation of tip-sample interactions in atomic force microscopy
Authors: Labuda Aleksander , Lysy Martin , Grütter Peter
Published: September 2012

Atomic force microscopy (AFM) simulators, which are used to gain insight into tip-sample physics and data interpretation, so far have been optimized for modeling deterministic cantilever dynamics. In this article, we demonstrate a method for semi-empirical simulation of the stochastic dynamics of tip-sample interactions. The detection, force, and displacement noises are separately generated directly from their numerically defined power spectral densities and used to simulate a force spectroscopy experiment in water at the mica interface. Mechanical noise of the AFM is shown to dominate over thermal noise of the cantilever upon interaction with the last two hydration layers.
Strength analysis and optimisation of double-toroidal anvils for high-pressure research
Authors: Fang J. , Bull C. L. , Loveday J. S. , Nelmes R. J. , Kamenev K. V.
Published: September 2012

We used the finite element method for stress and deformation analysis of the large sample volume double-toroidal anvil and gasket assembly used with the Paris-Edinburgh press for neutron scattering, in order to investigate the failure of this assembly observed repeatedly in experiments at a load of approximately 240 tonnes. The analysis is based on a new approach to modelling an opposed anvil device working under extreme stress conditions. The method relies on use of experimental data to validate the simulation in the absence of the material property data available for high pressure conditions. Using this method we analysed the stress distribution on the surface and in the bulk of the double-toroidal anvils, and we conclude that the failure occurs on the surface of the anvil and that it is caused by the tensile stress. We also use the model to show possible ways of optimising the anvil design in order to extend its operational pressure range.
A new four-dimensional ab initio potential energy surface for N2O–He and vibrational band origin shifts for the N2O–HeN clusters with N = 1–40
Authors: Wang Lecheng , Xie Daiqian , Le Roy Robert J. , Roy Pierre-Nicholas
Published: September 2012

A new four-dimensional ab initio potential energy surface for N2O−He is constructed at the CCSD(T) level with an aug-cc-pVQZ basis set together with bond functions. The vibrational coordinates Q1 and Q3 of N2O are explicitly included, due to the strong coupling between the symmetric and asymmetric stretches of N2O. A global potential energy surface is obtained by fitting the original potential points to a four-dimensional Morse/long range (MLR) analytical form. In the fitting, the ab initio noise in the long range region of the potential is smoothed over by theoretically fixed long range parameters. Two-dimensional intermolecular potentials for both the ground and the excited υ3 states of N2O are then constructed by vibrationally averaging the four-dimensional potential. Based on the two-dimensional potentials, we use the path integral Monte Carlo algorithm to calculate the vibrational band origin shifts for the N2O−HeN clusters using a first order perturbation theory estimate. The calculated shifts agree reasonably well with the experimental values and reproduce the evolution tendency from dimer to large clusters.
Hexatic phase and water-like anomalies in a two-dimensional fluid of particles with a weakly softened core
Authors: Prestipino Santi , Saija Franz , Giaquinta Paolo V.
Published: September 2012

We study a two-dimensional fluid of particles interacting through a spherically symmetric and marginally soft two-body repulsion. This model can exist in three different crystal phases, one of them with square symmetry and the other two triangular. We show that, while the triangular solids first melt into a hexatic fluid, the square solid is directly transformed on heating into an isotropic fluid through a first-order transition, with no intermediate tetratic phase. In the low-pressure triangular and square crystals, melting is reentrant provided the temperature is not too low, but without the necessity of two competing nearest-neighbor distances over a range of pressures. A whole spectrum of water-like fluid anomalies completes the picture for this model potential.
Fourier space approach to the classical density functional theory for multi-Yukawa and square-well fluids
Authors: Hlushak Stepan P. , McCabe Clare , Cummings Peter T.
Published: September 2012

We present a Fourier space density functional approach for hard particles with attractive interactions, which is based on a previously developed two-dimensional approach [S. Hlushak, W. Rżysko, and S. Sokołowski, J. Chem. Phys. 131, 094904 (2009)10.1063/1.3213623] for hard-sphere chains. The interactions are incorporated by means of a three-dimensional Fourier image of the direct correlation function that is obtained from the first-order mean-spherical approximation. In order to improve the computational efficiency, we make extensive use of fast Fourier transforms for calculating density convolution integrals. A two-dimensional implementation of the new density functional approach, based on the expansion of the functional around the bulk fluid density, is used to study structure and adsorption of two model fluids in narrow cylindrical pores. We also investigate two methods that improve the accuracy of the theory as compared to the conventional DFT approach, which expands the free energy functional around the bulk fluid density: One a variant of the reference fluid density functional theory used by Gillespie et al. [Phys. Rev. E 68, 031503 (2003)10.1103/PhysRevE.68.031503], and the second a weighted density approach with energy route thermodynamics. Results from these two methods are compared to the conventional approach and also to the results of Monte Carlo simulations. We find that the method of Gillespie et al. and the weighted density approach with energy route thermodynamics yield significant improvement over the conventional approach.
Growth of continuous and ultrathin platinum films on tungsten adhesion layers using atomic layer deposition techniques
Authors: Baker L. , Cavanagh A. S. , Yin J. , George S. M. , Kongkanand A. , Wagner F. T.
Published: September 2012

Continuous and ultrathin platinum (Pt) films were deposited on tungsten (W) adhesion layers using atomic layer deposition (ALD) techniques. Pt ALD films were deposited at 120 °C using MeCpPtMe3 and H2 plasma as the reactants. X-ray reflectivity studies observed the rapid nucleation of the Pt film. X-ray photoelectron results were consistent with layer-by-layer growth suggesting a continuous Pt film at thicknesses ≥1.5 nm. The high surface energy of the W ALD adhesion layer enables the growth of continuous and ultrathin films of lower surface energy metals and should facilitate the use of precious metals for a variety of applications.
Multi-scale order in amorphous transparent oxide thin films
Authors: Yan Aiming , Sun Tao , Borisenko Konstantin B. , Buchholz D. Bruce , Chang Robert P. H. , Kirkland Angus I. , Dravid Vinayak P.
Published: September 2012

Nominally “diffraction amorphous” materials represent a pervasive challenge in establishing classical structure-property relationships. This stems from the difficulty in defining the structure of nominally amorphous materials and experimentally differentiating the short-range (<10 Å) and medium-range (10 to 30 Å) order as a function of process parameters which are important due to their influence on physical, chemical, or transport properties. Herein, we report on the determination of short- and medium-range order in nominally amorphous zinc and tin co-substituted indium oxide In1.4Zn0.3Sn0.3O3 (a-ZITO) thin films grown by pulsed laser deposition. These thin films are being explored as transparent conductors that exhibit changes in transport properties depending on deposition temperature while remaining “diffraction amorphous.” Reduced density function (RDF) analysis from electron diffraction accompanied by density functional theory molecular dynamics simulation of a liquid quench suggests ordering at short range. Scanning transmission fluctuation electron microscopy (STFEM) indicates the presence of ordered ZITO regions at medium range. For a-ZITO films grown at different temperatures, RDF analysis showed no significant change in the short range order. However, STFEM revealed notable structural (and symmetry) differences at medium range. The existence of this type of multi-scale local order in amorphous ZITO thin films highlights the importance of a combined approach to unravel the structures of nominally amorphous materials and to understand structure-properties correlations.
Self consistent radio-frequency wave propagation and peripheral direct current plasma biasing: Simplified three dimensional non-linear treatment in the “wide sheath” asymptotic regime
Authors: Colas L. , Jacquot J. , Heuraux S. , Faudot E. , Crombé K. , Kyrytsya V. , Hillairet J. , Goniche M.
Published: September 2012

A minimal two-field fluid approach is followed to describe the radio-frequency (RF) wave propagation in the bounded scrape-off layer plasma of magnetic fusion devices self-consistently with direct current (DC) biasing of this plasma. The RF and DC parts are coupled by non-linear RF and DC sheath boundary conditions at both ends of open magnetic field lines. The physical model is studied within a simplified framework featuring slow wave (SW) only and lateral walls normal to the straight confinement magnetic field. The possibility is however kept to excite the system by any realistic 2D RF field map imposed at the outer boundary of the simulation domain. The self-consistent RF + DC system is solved explicitly in the asymptotic limit when the width of the sheaths gets very large, for several configurations of the RF excitation and of the target plasma. In the case of 3D parallelepipedic geometry, semi-analytical results are proposed in terms of asymptotic waveguide eigenmodes that can easily be implemented numerically. The validity of the asymptotic treatment is discussed and is illustrated by numerical tests against a quantitative criterion expressed from the simulation parameters. Iterative improvement of the solution from the asymptotic result is also outlined. Throughout the resolution, key physical properties of the solution are presented. The radial penetration of the RF sheath voltages along lateral walls at both ends of the open magnetic field lines can be far deeper than the skin depth characteristic of the SW evanescence. This is interpreted in terms of sheath-plasma wave excitation. Therefore, the proper choice of the inner boundary location is discussed as well as the appropriate boundary conditions to apply there. The asymptotic scaling of various quantities with the amplitude of the input RF excitation is established.
A new method to calculate the beam charge for an integrating current transformer
Authors: Wu Yuchi , Han Dan , Zhu Bin , Dong Kegong , Tan Fang , Gu Yuqiu
Published: September 2012

The integrating current transformer (ICT) is a magnetic sensor widely used to precisely measure the charge of an ultra-short-pulse charged particle beam generated by traditional accelerators and new laser-plasma particle accelerators. In this paper, we present a new method to calculate the beam charge in an ICT based on circuit analysis. The output transfer function shows an invariable signal profile for an ultra-short electron bunch, so the function can be used to evaluate the signal quality and calculate the beam charge through signal fitting. We obtain a set of parameters in the output function from a standard signal generated by an ultra-short electron bunch (about 1 ps in duration) at a radio frequency linear electron accelerator at Tsinghua University. These parameters can be used to obtain the beam charge by signal fitting with excellent accuracy.
Electrical and heat conduction mechanisms of GeTe alloy for phase change memory application
Authors: Lan Rui , Endo Rie , Kuwahara Masashi , Kobayashi Yoshinao , Susa Masahiro
Published: September 2012

GeTe alloy has drawn much attention as one of the promising candidates for phase change memory application. In this work, the electrical resistivities and thermal conductivities of GeTe alloy have been determined as functions of temperature by the four-terminal method and hot strip method, respectively. The electrical resistivity increases and the thermal conductivity decreases monotonically with increasing temperature, and thus it is likely that free electron dominates the thermal conduction. The electrical resistivity increases slowly with time during holding at 773 K, and the thermal conductivity decreases corresponding to the change of the electrical resistivity, which suggests that small amount of high temperature phase might exist in the samples.
Tunable electronic transport characteristics through an AA-stacked bilayer graphene with magnetoelectric barriers
Authors: Wang Dali , Jin Guojun
Published: September 2012

We study the electronic transport through an AA-stacked bilayer graphene with magnetic and electric barriers when an external electric field is applied perpendicularly to the graphene plane. The tunneling probability is found to be highly sensitive with respect to the incident angle of Dirac electrons, magnetic barrier strength, and biased potential between the two graphene layers. We also demonstrate that the electronic conductance across such a barrier structure can change from an oscillatory to a monotonically decaying function of the barrier width beyond a critical magnetic field, and further can be effectively modified by the electrical potential difference between the layers. It is possible to achieve conduction modulation in the AA-stacked bilayer graphene with configurable magnetoelectric barriers and to realize a field-induced switching by means of the combination of the magnetic and electric fields.
Size-dependent emission efficiency and luminescence characteristics of YBO3:Tb3+ nanocrystals under vacuum ultraviolet excitations
Authors: Sharma Prashant K. , Dutta Ranu K. , Pandey Avinash C.
Published: September 2012

The luminous efficiency and lifetime of plasma display panels (PDPs) are directly related to the performance of phosphors used in PDPs, thus higher efficiency, higher stability against high temperature processes, and a long lifetime along with good color chromaticity against vacuum-ultraviolet radiation are major concerns in selecting suitable phosphors for PDPs. In the same pursuit, well crystallized pure hexagonal phase YBO3:Tb3+ nanocrystals were prepared using co-precipitation method. The prepared YBO3:Tb3+ nanocrystals showed bright green luminescence, color chromaticity (0.21, 0.61), and could be assigned to 5D4→7Fj transitions (j = 2-6) due to electric dipole–dipole interaction of Tb3+ ions. The vacuum ultraviolet photoluminescence spectroscopy of the prepared YBO3:Tb3+ nanocrystals showed size dependent nonlinear luminescence enhancement with relatively shorter life time as compared to the commercial bulk YBO3:Tb3+ phosphor. The quenching concentration of Tb3+ doping for (5D4→7F5) transition was found significantly enhanced with the decrease in particle size suggesting it an ideal green phosphor for plasma display panels. The possible explanation for size-dependent emission efficiency and observed luminescence characteristics were proposed via charge transfer process and lowering of the structural symmetry.
Fast acoustic tweezers for the two-dimensional manipulation of individual particles in microfluidic channels
Authors: Tran S. B. Q. , Marmottant P. , Thibault P.
Published: September 2012

This paper presents a microfluidic device that implements standing surface acoustic waves in order to handle single cells, droplets, and generally particles. The particles are moved in a very controlled manner by the two-dimensional drifting of a standing wave array, using a slight frequency modulation of two ultrasound emitters around their resonance. These acoustic tweezers allow any type of motion at velocities up to few ×10 mm/s, while the device transparency is adapted for optical studies. The possibility of automation provides a critical step in the development of lab-on-a-chip cell sorters and it should find applications in biology, chemistry, and engineering domains.
Localized tail state distribution in amorphous oxide transistors deduced from low temperature measurements
Authors: Lee Sungsik , Nathan Arokia
Published: September 2012

In this paper, we extract density of localized tail states from measurements of low temperature conductance in amorphous oxide transistors. At low temperatures, trap-limited conduction prevails, allowing extraction of the trapped carrier distribution with energy. Using a test device with a-InGaZnO channel layer, the extracted tail state energy and density at the conduction band minima are 20 meV and 2 × 1019 cm−3 eV−1, respectively, which are consistent with values reported in the literature. Also, the field-effect mobility as a function of temperature from 77 K to 300 K is retrieved for different gate voltages, yielding the activation energy and the percolation threshold.
Prediction of strong ground state electron and hole wave function spatial overlap in nonpolar GaN/AlN quantum dots
Authors: Schulz S. , Caro M. A. , O'Reilly E. P.
Published: September 2012

We present a detailed analysis of the electrostatic built-in field, the electronic structure, and the optical properties of a-plane GaN/AlN quantum dots with an arrowhead-shaped geometry. This geometry is based on extensive experimental analysis given in the literature. Our results indicate that the spatial overlap of electron and hole ground state wave functions is significantly increased, compared to that of a c-plane system, when taking the experimentally suggested trapezoid-shaped dot base into account. This finding is in agreement with experimental data on the optical properties of a-plane GaN/AlN quantum dots.
Estimation of radon diffusion coefficients in soil using an updated experimental system
Authors: Prasad Ganesh , Ishikawa Tetsuo , Hosoda Masahiro , Sorimachi Atsuyuki , Janik Miroslaw , Sahoo Sarata Kumar , Tokonami Shinji , Uchida Shigeo
Published: September 2012

Radon diffusion through soil is strongly affected by the degree of water saturation of the soil pores. Methods have been developed by many researchers to measure radon diffusion coefficient. We developed an updated experimental system to estimate radon diffusion coefficients for typical types of soil in Japan and applied it to a typical loam with different water saturation levels (0–0.82). The system consists of a passive-type scintillation cell, soil column, accumulation tank, and radon source. The radon concentration in the accumulation tank is kept stable, and radon diffused through the soil column is continuously measured with the passive-type scintillation cell. We found the radon diffusion coefficients vary from 9.60 × 10−6 m2 s−1 to 1.27 × 10−7 m2 s−1 for the loam samples. Generally, the diffusion coefficients are almost constant for a water saturation range of 0–0.4 and decrease with increasing water saturation from 0.4 to 0.82.
Corrigendum to: Estimating the amount of water required to extinguish wildfires under different conditions and in various fuel types
Authors: Hansen Rickard
Published: September 2012

In wildland fires where water is used as the primary extinguishing agent, one of the issues of wildfire suppression is estimating how much water is required to extinguish a certain section of the fire. In order to use easily distinguished and available indicators, the flame length and the area of the active combustion zone were chosen as suitable for the modelling of extinguishing requirements. Using Byram's and Thomas' equations, the heat release rate per unit length of fire front was calculated for low-intensity surface fires, fires with higher wind conditions, fires in steep terrain and high-intensity crown fires. Based on the heat release rate per unit length of fire front, the critical water flow rate was calculated for the various cases. Further, the required amount of water for a specific active combustion zone area was calculated for various fuel models. Finally, the results for low-intensity surface fires were validated against fire experiments. The calculated volumes of water can be used both during the preparatory planning for incidents as well as during firefighting operations.
Collaborative interplay between FGF-2 and VEGF-C promotes lymphangiogenesis and metastasis
Authors: Cao Renhai , Ji Hong , Feng Ninghan , Zhang Yin , Yang Xiaojuan , Andersson Patrik , Sun Yuping , Tritsaris Katerina , Hansen Anker Jon , Dissing Steen , Cao Yihai
Published: September 2012

Interplay between various lymphangiogenic factors in promoting lymphangiogenesis and lymphatic metastasis remains poorly understood. Here we show that FGF-2 and VEGF-C, two lymphangiogenic factors, collaboratively promote angiogenesis and lymphangiogenesis in the tumor microenvironment, leading to widespread pulmonary and lymph-node metastases. Coimplantation of dual factors in the mouse cornea resulted in additive angiogenesis and lymphangiogenesis. At the molecular level, we showed that FGFR-1 expressed in lymphatic endothelial cells is a crucial receptor that mediates the FGF-2–induced lymphangiogenesis. Intriguingly, the VEGFR-3–mediated signaling was required for the lymphatic tip cell formation in both FGF-2– and VEGF-C–induced lymphangiogenesis. Consequently, a VEGFR-3–specific neutralizing antibody markedly inhibited FGF-2–induced lymphangiogenesis. Thus, the VEGFR-3–induced lymphatic endothelial cell tip cell formation is a prerequisite for FGF-2–stimulated lymphangiogenesis. In the tumor microenvironment, the reciprocal interplay between FGF-2 and VEGF-C collaboratively stimulated tumor growth, angiogenesis, intratumoral lymphangiogenesis, and metastasis. Thus, intervention and targeting of the FGF-2– and VEGF-C–induced angiogenic and lymphangiogenic synergism could be potentially important approaches for cancer therapy and prevention of metastasis.
Rhythmic ring–ring stacking drives the circadian oscillator clockwise
Authors: Chang Yong-Gang , Tseng Roger , Kuo Nai-Wei , LiWang Andy
Published: September 2012

The oscillator of the circadian clock of cyanobacteria is composed of three proteins, KaiA, KaiB, and KaiC, which together generate a self-sustained ∼24-h rhythm of phosphorylation of KaiC. The mechanism propelling this oscillator has remained elusive, however. We show that stacking interactions between the CI and CII rings of KaiC drive the transition from the phosphorylation-specific KaiC–KaiA interaction to the dephosphorylation-specific KaiC–KaiB interaction. We have identified the KaiB-binding site, which is on the CI domain. This site is hidden when CI domains are associated as a hexameric ring. However, stacking of the CI and CII rings exposes the KaiB-binding site. Because the clock output protein SasA also binds to CI and competes with KaiB for binding, ring stacking likely regulates clock output. We demonstrate that ADP can expose the KaiB-binding site in the absence of ring stacking, providing an explanation for how it can reset the clock.
Hypersurfaces of constant higher order mean curvature in warped products
Authors: Alías Luis , Impera Debora , Rigoli Marco
Published: September 2012

In this paper we characterize compact and complete hypersurfaces with some constant higher order mean curvature into warped product spaces. Our approach is based on the use of a new trace operator version of the Omori-Yau maximum principle which seems to be interesting in its own.
Verticillium dahliae Sge1 Differentially Regulates Expression of Candidate Effector Genes
Authors: Santhanam Parthasarathy , Thomma Bart P. H. J.
Published: September 2012

The ascomycete fungus Verticillium dahliae causes vascular wilt diseases in hundreds of dicotyledonous plant species. However, thus far, only few V. dahliae effectors have been identified, and regulators of pathogenicity remain unknown. In this study, we investigated the role of the V. dahliae homolog of Sge1, a transcriptional regulator that was previously implicated in pathogenicity and effector gene expression in Fusarium oxysporum. We show that V. dahliae Sge1 (VdSge1) is required for radial growth and production of asexual conidiospores, because VdSge1 deletion strains display reduced radial growth and reduced conidia production. Furthermore, we show that VdSge1 deletion strains have lost pathogenicity on tomato. Remarkably, VdSge1 is not required for induction of Ave1, the recently identified V. dahliae effector that activates resistance mediated by the Ve1 immune receptor in tomato. Further assessment of the role of VdSge1 in the induction of the nine most highly in-planta-induced genes that encode putative effectors revealed differential activity. Although the expression of one putative effector gene in addition to Ave1 was not affected by VdSge1 deletion, VdSge1 appeared to be required for the expression of six putative effector genes, whereas two of the putative effectors genes were found to be negatively regulated by VdSge1. In conclusion, our data suggest that VdSge1 differentially regulates V. dahliae effector gene expression.
Storage Rot of Dragon Fruit Caused by Gilbertella persicaria
Authors: Guo L. W. , Wu Y. X. , Mao Z. C. , Ho H. H. , He Y. Q.
Published: September 2012

In October 2011, a new disease of dragon fruit (Hylocereus costaricensis) was discovered in a fruit market in Yuanjiang, Yunnan Province, China. Small, light brown, water-soaked spots appeared initially and then coalesced, extending to the entire fruit in 6 days. Hyaline hyphae and light brown sporangia were observed over the entire surface of the infected fruit. On potato sucrose agar (PSA) the fungus produced a white, appressed colony that covered a 9-cm diameter petri dish in less than 5 days at 25°C. The sporangiophores were hyaline, light brown to grayish, 44.71 to 143.14 (average = 85.10) μm long, and arose directly from the non-septate substrate hyphae. The sporangia were spherical, single, and terminal and yellow-brown to brown when young turning to dark brown or black at maturity. Both the sporangiophores and sporangia were covered with calcium oxalate crystals. When mounted in a drop of water, the sporangium immediately broke longitudinally into two halves, releasing the spores and exposing a large pyriform columella at the tip of the sporangiophore. The spores were mostly globose to ellipsoid, aseptate, and 5.15 (3.71 to 7.86) × 6.30 (4.08 to 9.19) μm (n = 300). Two to three slender, hyaline appendages were attached to the ends of the spores. The cardinal growth temperatures of the pathogen were 10, 30, and 40°C and it grew faster in the dark than under 12-h alternating light-dark cycles. The fungus was identified as Gilbertella persicaria (1). To confirm the identification, the internal transcribed spacer region of the nuclear rDNA of one isolate was amplified using the fungal primers ITS1 and ITS4. The nucleotide sequence (Accession No. JQ951601) showed 98% homology with G. persicaria in GenBank (HM999958). Pathogenicity tests were carried out on two species of dragon fruit, H. costaricensis and H. undatus, by placing a 6-mm diameter young mycelial PSA agar disc on the surface of an asymptomatic fruit, either unwounded or wounded with a sterile needle. As the control, a plain PSA disc was used. Each inoculated fruit was placed in a moist chamber and incubated at 25°C. Three fruits were used per treatment and the experiment was repeated twice. The fruits rotted in 2 to 3 days, and the disease was especially serious on wounded fruits and on H. costaricensis. The fungus was reisolated from infected fruits. The controls did not show any disease symptoms. Inoculation studies were also made on other fruits but rot was produced only on peach, pear, and wounded tomato. To our knowledge, this is the first record of dragon fruit rot caused by G. persicaria. The fungus had been reported in China but caused no diseases (2). In India, it caused fruit rot of pear, tomato, and peach (3). To minimize the disease, dragon fruit should be stored at low temperature and in uncovered containers.

References: (1) G. L. Benny. Mycologia 83:150, 1991. (2) J. Y. Cheng and H. Y. Mei. Acta Phytotax. Sin. 10:105, 1965. (3) M. D. Mehrotra. Mycopath. Mycol. Appl. 29:151, 1966.
Endosymbiotic bacteria as a source of carotenoids in whiteflies
Authors: Sloan Daniel B. , Moran Nancy A.
Published: September 2012

Although carotenoids serve important biological functions, animals are generally unable to synthesize these pigments and instead obtain them from food. However, many animals, such as sap-feeding insects, may have limited access to carotenoids in their diet, and it was recently shown that aphids have acquired the ability to produce carotenoids by lateral transfer of fungal genes. Whiteflies also contain carotenoids but show no evidence of the fungus-derived genes found in aphids. Because many sap-feeding insects harbour intracellular bacteria, it has long been hypothesized that these endosymbionts could serve as an alternative source of carotenoid biosynthesis. We sequenced the genome of the obligate bacterial endosymbiont
Portiera
from the whitefly
Bemisia tabaci
. The genome exhibits typical signatures of obligate endosymbionts in sap-feeding insects, including extensive size reduction (358.2 kb) and enrichment for genes involved in essential amino acid biosynthesis. Unlike other sequenced insect endosymbionts, however,
Portiera
has bacterial homologues of the fungal carotenoid biosynthesis genes in aphids. Therefore, related lineages of sap-feeding insects appear to have convergently acquired the same functional trait by distinct evolutionary mechanisms—bacterial endosymbiosis versus fungal lateral gene transfer.
Multiwalled carbon nanotubes in alfalfa and wheat: toxicology and uptake
Authors: Miralles Pola , Johnson Errin , Church Tamara L. , Harris Andrew T.
Published: September 2012

Data on the bioavailability and toxicity of carbon nanotubes (CNTs) in the environment, and, in particular, on their interactions with vascular plants, are limited. We investigated the effects of industrial-grade multiwalled CNTs (75 wt% CNTs) and their impurities on alfalfa and wheat. Phytotoxicity assays were performed during both seed germination and seedling growth. The germinations of both species were tolerant of up to 2560 mg l
−1
CNTs, and root elongation was enhanced in alfalfa and wheat seedlings exposed to CNTs. Remarkably, catalyst impurities also enhanced root elongation in alfalfa seedlings as well as wheat germination. Thus the impurities, not solely the CNTs, impacted the plants. CNT internalization by plants was investigated using electron microscopy and two-dimensional Raman mapping. The latter showed that CNTs were adsorbed onto the root surfaces of alfalfa and wheat without significant uptake or translocation. Electron microscopy investigations of internalization were inconclusive owing to poor contrast, so Fe
3
O
4
-functionalized CNTs were prepared and studied using energy-filter mapping of Fe
3
O
4
. CNTs bearing Fe
3
O
4
nanoparticles were detected in the epidermis of one wheat root tip only, suggesting that internalization was possible but unusual. Thus, alfalfa and wheat tolerated high concentrations of industrial-grade multiwalled CNTs, which adsorbed onto their roots but were rarely taken up.
Shape optimization in exoskeletons and endoskeletons: a biomechanics analysis
Authors: Taylor David , Dirks Jan-Henning
Published: September 2012

This paper addresses the question of strength and mechanical failure in exoskeletons and endoskeletons. We developed a new, more sophisticated model to predict failure in bones and other limb segments, modelled as hollow tubes of radiusrand thicknesst. Five failure modes were considered: transverse fracture; buckling (of three different kinds) and longitudinal splitting. We also considered interactions between failure modes. We tested the hypothesis that evolutionary adaptation tends towards an optimum value ofr/t, this being the value which gives the highest strength (i.e. load-carrying capacity) for a given weight. We analysed two examples of arthropod exoskeletons: the crab merus and the locust tibia, using data from the literature and estimating the stresses during typical activities. In both cases, the optimumr/tvalue for bending was found to be different from that for axial compression. We found that the crab merus experiences similar levels of bending and compressionin vivoand that itsr/tvalue represents an ideal compromise to resist these two types of loading. The locust tibia, however, is loaded almost exclusively in bending and was found to be optimized for this loading mode. Vertebrate long bones were found to be far from optimal, having much lowerr/tvalues than predicted, and in this respect our conclusions differ from those of previous workers. We conclude that our theoretical model, though it has some limitations, is useful for investigating evolutionary development of skeletal form in exoskeletons and endoskeletons.
Separating spatial search and efficiency rates as components of predation risk
Authors: DeCesare Nicholas J.
Published: September 2012

Predation risk is an important driver of ecosystems, and local spatial variation in risk can have population-level consequences by affecting multiple components of the predation process. I use resource selection and proportional hazard time-to-event modelling to assess the spatial drivers of two key components of risk—the search rate (i.e. aggregative response) and predation efficiency rate (i.e. functional response)—imposed by wolves (
Canis lupus
) in a multi-prey system. In my study area, both components of risk increased according to topographic variation, but anthropogenic features affected only the search rate. Predicted models of the cumulative hazard, or risk of a kill, underlying wolf search paths validated well with broad-scale variation in kill rates, suggesting that spatial hazard models provide a means of scaling up from local heterogeneity in predation risk to population-level dynamics in predator–prey systems. Additionally, I estimated an integrated model of relative spatial predation risk as the product of the search and efficiency rates, combining the distinct contributions of spatial heterogeneity to each component of risk.