bluuebunny/crossref_metadata_2025 huggingface dataset:
Optimization of magnetic switches for single particle and cell transport
Authors: Abedini-Nassab Roozbeh , Murdoch David M. , Kim CheolGi , Yellen Benjamin B.
Published: June 2014

The ability to manipulate an ensemble of single particles and cells is a key aim of lab-on-a-chip research; however, the control mechanisms must be optimized for minimal power consumption to enable future large-scale implementation. Recently, we demonstrated a matter transport platform, which uses overlaid patterns of magnetic films and metallic current lines to control magnetic particles and magnetic-nanoparticle-labeled cells; however, we have made no prior attempts to optimize the device geometry and power consumption. Here, we provide an optimization analysis of particle-switching devices based on stochastic variation in the particle's size and magnetic content. These results are immediately applicable to the design of robust, multiplexed platforms capable of transporting, sorting, and storing single cells in large arrays with low power and high efficiency.
General bidirectional thermal characterization via the 3ω technique
Authors: Bauer Matthew L. , Norris Pamela M.
Published: June 2014

The 3ω technique has become a popular method for determining the thermophysical properties of microscale and bulk materials. The prerequisite fabrication of a highly linear metal line a few hundred nanometers thick on the sample can be a failing point in specific material systems. This difficulty can be overcome by utilizing a bidirectional experimental geometry that employs a contact resistance between the sample and heating wire, which also allows for data collection under varying axial pressure loads. In this work, such a system is demonstrated with an emphasis on developing a thermal mount that will optimize sensitivity to the thermophysical parameters of interest: the sample's thermal conductivity, volumetric heat capacity, and the contact resistance between the sample and mount. A general thermal model is presented that can be simplified to analyze nearly any similar system. This model is then employed to analyze a sample in the mounting scheme described with varying applied pressures to demonstrate the general feasibility of the system.
Experimental verification of the high pressure crystal structures in NH3BH3
Authors: Huang Yanping , Huang Xiaoli , Zhao Zhonglong , Li Wenbo , Jiang Shuqing , Duan Defang , Bao Kuo , Zhou Qiang , Liu Bingbing , Cui Tian
Published: June 2014

A detailed high-pressure study on NH3BH3 has been carried out using in situ synchrotron X-ray diffraction (XRD) and Raman scattering with a diamond anvil cell up to 20 and 33 GPa, respectively. The Rietveld refinement based on the XRD pattern and analysis of Raman data indicate two first-order phase transitions from the ambient pressure I4 mm structure (α-NH3BH3) to a high pressure Cmc21 phase (β-NH3BH3) at 2.14 GPa, and further into a monoclinic P21 (Z = 2) phase (γ-NH3BH3) at 9.67 GPa. Fitting the measured volumetric compression data to the third order Birch-Murnaghan equation of state reveals a bulk modulus of B0 = 9.9 ± 0.5 and 17.0 ± 3.0 GPa (with fixed B0′ = 4) for the β-NH3BH3 below and above 5 GPa, respectively. Still, with the splitting of the NBH rock mode in Raman experiment, it is concluded that a second-order isostructural phase transition occurs at 5 GPa. By analyzing the dihydrogen bonding framework, the origin of the isostructural phase transition is attributed to the number of dihydrogen bondings per molecule in the Cmc21 phase increasing from 12 to 14 at 5 GPa.
Development of high-voltage pulse generator with variable amplitude and duration
Authors: Upadhyay J. , Sharma M. L. , Ahuja Aakash B. , Navathe C. P.
Published: June 2014

A high voltage pulse generator with variable amplitude (100–3000 V) and duration (100–2000 μs) has been designed and developed. The variable duration pulse has been generated by adopting a simple and novel technique of varying the turn off delay time of a high voltage Metal Oxide Semiconductor Field Effect Transistor (MOSFET) based switch by varying external gate resistance. The pulse amplitude is made variable by adjusting biasing supply of the high voltage switch. The high voltage switch has been developed using a MOSFET based stack of 3 kV rating with switching time of 7 ns.
Far infrared laser polarimetry and far forward scattering diagnostics for the C-2 field reversed configuration plasmas
Authors: Deng B. H. , Kinley J. S. , Knapp K. , Feng P. , Martinez R. , Weixel C. , Armstrong S. , Hayashi R. , Longman A. , Mendoza R. , Gota H. , Tuszewski M.
Published: June 2014

A two-chord far infrared (FIR) laser polarimeter for high speed sub-degree Faraday rotation measurements in the C-2 field reversed configuration experiment is described. It is based on high power proprietary FIR lasers with line width of about 330 Hz. The exceptionally low intrinsic instrument phase error is characterized with figures of merit. Significant toroidal magnetic field with rich dynamics is observed. Simultaneously obtained density fluctuation spectra by far forward scattering are presented.
A broadband solar absorber with 12 nm thick ultrathin a-Si layer by using random metallic nanomeshes
Authors: Sun Tianyi , Fei Guo Chuan , Cao Feng , Metin Akinoglu Eser , Wang Yang , Giersig Michael , Ren Zhifeng , Kempa Krzysztof
Published: June 2014

We show in theory, simulations, and experiments that, by applying random metallic nanomeshes, a broad-band multilayered structure with a 12 nm thick a-Si film as the active layer can absorb 89% of the total solar energy in the visible range from 400 nm to 700 nm. Such broadness and high absorption can be attributed to the random scattering introduced by the aperiodic metallic nanomeshes and the plasmonic-metamaterial design. The broadband and smooth electromagnetic response, combined with a very high absorption, is desired for solar energy harvesting devices, making this structure a good candidate for high efficiency photovoltaics with ultra-thin active layers.
The semi-empirical tight-binding model for carbon allotropes “between diamond and graphite”
Authors: Lytovchenko V. , Kurchak A. , Strikha M.
Published: June 2014

The new carbon allotropes “between diamond and graphite” have come under intensive examination during the last decade due to their numerous technical applications. The modification of energy gap in thin films of these allotropes was studied experimentally using optical methods. The proposed simple model of carbon clusters with variable lengths of chemical bonds allows us to imitate the transfer from diamond and diamond-like to graphite-like structures, as well as the corresponding modification of hybridization sp3/sp2 for diamond-like and spz for graphite-like phases. This enables us to estimate various allotropes parameters, like the gap Eg, energies of valence Ev, and conduction Ec band edges, and the value of electronic affinity, i.e., optical work function X, which are all of practical importance. The obtained estimations correspond to the experimental data.
Design considerations for high-Q bandpass microwave oscillator sensors based upon resonant amplification
Authors: Jones A. Mark , Kelly James F. , Tedeschi Jonathan , McCloy John S.
Published: June 2014

A series of microwave resonant oscillator sensors were designed and characterized using bandpass planar and volumetric electrical resonators having loaded quality factor (Q) values in the range of 2 to 20. The use of these resonators in positive feedback circuits yielded sensor Q-factors of up to 2 × 107, demonstrating Q-factor amplifications on the order of 106. It is shown that the Q-factor amplification can be increased in a positive feedback system through the selection of feedback loop group delay, allowing use of resonators with lower static, loaded Q-factor values. A low-frequency electromagnetic interference sensing application is demonstrated for two resonant oscillator configurations, showing considerable frequency sensitivity to 45 kHz emitters.
Experimental and simulation study of the impact of increased photovoltaic integration with the grid
Authors: Shafiullah G. M. , Oo Amanullah M. T. , Ali A. B. M. Shawkat , Wolfs Peter , Stojcevski Alex
Published: June 2014

The abundance, availability, and climate-friendly characteristics of solar photovoltaic (PV) energy encourage nations around the globe to adopt it to assist in overcoming global warming as well as build a sustainable society for the future. The intermittent nature of solar energy generation and the associated power electronic inverters with connected consumer loads creates a number of potential challenges in integrating large-scale PV into the grid that affects power quality of the distribution networks. This paper investigates the impacts of varying PV integration into the grid through experimental and simulation studies. Initially, several experiments were conducted with varying PV penetration and load conditions using the Renewable Energy Integration Facility at CSIRO, Newcastle, Australia. Later, a simulation model was developed that mimics the experimental facility used at CSIRO to investigate the adverse impacts on integrating large-scale PV into the grid using the power system simulation software PSS Sincal. Experimental and simulation analyses clearly indicate that integration of PV into the grid causes power quality issues such as voltage instability, harmonic injection, and low power factor into the networks and the level of these impacts increases with the increase of PV penetration.
Optical time of flight studies of lithium plasma in double pulse laser ablation: Evidence of inverse Bremsstrahlung absorption
Authors: Sivakumaran V. , Joshi H. C. , Singh R. K. , Kumar Ajai
Published: June 2014

The early stage of formation of lithium plasma in a collinear—double pulse laser ablation mode has been studied using optical time of flight (OTOF) spectroscopy as a function of inter-pulse delay time, the distance from the target surface and the fluence of the ablation lasers. The experimental TOF measurements were carried out for lithium neutral (670.8 nm and 610.3 nm), and ionic (548.4 nm and 478.8 nm) lines. These experimental observations have been compared with that for single pulse laser ablation mode. It is found that depending on the fluence and laser pulse shape of the first pre-ablation laser and the second main ablation laser, the plasma plume formation and its characteristic features can be described in terms of plume-plume or laser-plume interaction processes. Moreover, the enhancement in the intensity of Li neutral and ionic lines is observed when the laser-plume interaction is the dominant process. Here, we see the evidence of the role of inverse Bremsstrahlung absorption process in the initial stage of formation of lithium plasma in this case.
First principles investigation of the initial stage of H-induced missing-row reconstruction of Pd(110) surface
Authors: Padama Allan Abraham B. , Kasai Hideaki
Published: June 2014

The pathway of H diffusion that will induce the migration of Pd atom is investigated by employing first principles calculations based on density functional theory to explain the origin of missing-row reconstruction of Pd(110).The calculated activation barrier and the H-induced reconstruction energy reveal that the long bridge-to-tetrahedral configuration is the energetically favored process for the initial stage of reconstruction phenomenon. While the H diffusion triggers the migration of Pd atom, it is the latter process that significantly contributes to the activated missing-row reconstruction of Pd(110). Nonetheless, the strong interaction between the diffusing H and the Pd atoms dictates the occurrence of reconstructed surface.
Dynamic compressive and tensile strengths of spark plasma sintered alumina
Authors: Girlitsky I. , Zaretsky E. , Kalabukhov S. , Dariel M. P. , Frage N.
Published: June 2014

Fully dense submicron grain size alumina samples were manufactured from alumina nano-powder using Spark Plasma Sintering and tested in two kinds of VISAR-instrumented planar impact tests. In the first kind, samples were loaded by 1-mm tungsten impactors, accelerated to a velocity of about 1 km/s. These tests were aimed at studying the Hugoniot elastic limit (HEL) of Spark Plasma Sintering (SPS)-processed alumina and the decay, with propagation distance, of the elastic precursor wave. In the tests of the second kind, alumina samples of 3-mm thickness were loaded by 1-mm copper impactors accelerated to 100–1000 m/s. These tests were aimed at studying the dynamic tensile (spall) strength of the alumina specimens. The tensile fracture of the un-alloyed alumina shows a monotonic decline of the spall strength with the amplitude of the loading stress pulse. Analysis of the decay of the elastic precursor wave allowed determining the rate of the irreversible (inelastic) strains in the SPS-processed alumina at the initial stages of the shock-induced inelastic deformation and to clarify the mechanisms responsible for the deformation. The 1-% addition of Cr2O3 decreases the HEL of the SPS-processed alumina by 5-% and its spall strength by 50% but barely affects its static properties.
Copper doping of ZnO crystals by transmutation of 64Zn to 65Cu: An electron paramagnetic resonance and gamma spectroscopy study
Authors: Recker M. C. , McClory J. W. , Holston M. S. , Golden E. M. , Giles N. C. , Halliburton L. E.
Published: June 2014

Transmutation of 64Zn to 65Cu has been observed in a ZnO crystal irradiated with neutrons. The crystal was characterized with electron paramagnetic resonance (EPR) before and after the irradiation and with gamma spectroscopy after the irradiation. Major features in the gamma spectrum of the neutron-irradiated crystal included the primary 1115.5 keV gamma ray from the 65Zn decay and the positron annihilation peak at 511 keV. Their presence confirmed the successful transmutation of 64Zn nuclei to 65Cu. Additional direct evidence for transmutation was obtained from the EPR of Cu2+ ions (where 63Cu and 65Cu hyperfine lines are easily resolved). A spectrum from isolated Cu2+ (3d9) ions acquired after the neutron irradiation showed only hyperfine lines from 65Cu nuclei. The absence of 63Cu lines in this Cu2+ spectrum left no doubt that the observed 65Cu signals were due to transmuted 65Cu nuclei created as a result of the neutron irradiation. Small concentrations of copper, in the form of Cu+-H complexes, were inadvertently present in our as-grown ZnO crystal. These Cu+-H complexes are not affected by the neutron irradiation, but they dissociate when a crystal is heated to 900 °C. This behavior allowed EPR to distinguish between the copper initially in the crystal and the copper subsequently produced by the neutron irradiation. In addition to transmutation, a second major effect of the neutron irradiation was the formation of zinc and oxygen vacancies by displacement. These vacancies were observed with EPR.
Experiments with a pressure-driven Stirling refrigerator with flexible chambers
Authors: McFarlane Patrick , Suire Jonathan , Sen Mihir , Semperlotti Fabio
Published: June 2014

We report on the design and experimental testing of a Stirling refrigerator that uses air as the working fluid, and where the conventional piston-cylinder assemblies are replaced by pressure-driven flexible chambers. The two chambers are periodically compressed by pneumatic actuators resulting in airflow through the regenerator and in a net temperature difference between the chambers. An experimental setup is used to investigate the performance of the refrigerator under different operating conditions with particular attention to actuation frequencies, driving pressure differences, and phase angles between the two inputs. The time constant of the temperature difference between the two chambers is determined, and the temperature difference is measured as a function of the system parameters. The results of several tests conducted under different operating conditions show that the refrigerating effect is very robust and allows good performance even for modulated inputs. The frequency response is radically different from that of a traditional motion-driven device. This work suggests that mechanical to thermal energy conversion devices based on this principle can be successfully powered by human motion.
Finite element analysis and experimental study of surface acoustic wave propagation through two-dimensional pillar-based surface phononic crystal
Authors: Yankin S. , Talbi A. , Du Y. , Gerbedoen J.-C. , Preobrazhensky V. , Pernod P. , Bou Matar O.
Published: June 2014

We study both theoretically and experimentally the interaction of surface elastic waves with 2D surface phononic crystal (PnC) on a piezoelectric substrate. A rigorous analysis based on 3D finite element method is conducted to calculate the band structure of the PnC and to analyze the transmission spectrum (module and phase). Interdigital transducers (IDTs) are considered for electrical excitation and detection, and absorbing boundary conditions are used to suppress wave's reflection from the edges. The PnCs are composed of an array of 20 Nickel cylindrical pillars arranged in a square lattice symmetry, and deposited on a LiNbO3 substrate (128°Y cut-X propagating) between two dispersive IDTs. We investigate by means of band diagrams and transmission spectrum the opening band-gaps originating from pillars resonant modes and from Bragg band-gap. The physical parameters that influence and determine their appearance are also discussed. Experimental validation is achieved through electrical measurement of the transmission characteristics, including amplitude and phase.
Spin and phonon anomalies in epitaxial self-assembled CoFe2O4-BaTiO3 multiferroic nanostructures
Authors: Tsai C. Y. , Cheng H. M. , Chen H. R. , Huang K. F. , Tsai L. N. , Chu Y. H. , Lai C. H. , Hsieh W. F.
Published: June 2014

Temperature dependent magnetic and phonon anomalies in epitaxial self-assembled CoFe2O4 (CFO) rods embedded in BaTiO3 (BTO) matrix nanostructures were investigated. The temperature dependence of A1(2TO) phonon frequency of BTO indicates that the BTO matrix experiences structural transformations. The lattice strain produced during the structural transformations drives spin reorientation in CFO rods, resulting in anomalous changes of magnetization. Through correlating the phonon anomalies with the increase of in-plane spin ordering, we show the spin-phonon coupling induces the softening of A1g and A1(2TO) phonons. It suggests that spin strongly couples with lattice strain and phonons in this nanostructure.
Is light-induced degradation of a-Si:H/c-Si interfaces reversible?
Authors: El Mhamdi El Mahdi , Holovsky Jakub , Demaurex Bénédicte , Ballif Christophe , De Wolf Stefaan
Published: June 2014

Thin hydrogenated amorphous silicon (a-Si:H) films deposited on crystalline silicon (c-Si) surfaces are sensitive probes for the bulk electronic properties of a-Si:H. Here, we use such samples during repeated low-temperature annealing and visible-light soaking to investigate the long-term stability of a-Si:H films. We observe that during annealing the electronic improvement of the interfaces follows stretched exponentials as long as hydrogen evolution in the films can be detected. Once such evolution is no longer observed, the electronic improvement occurs much faster. Based on these findings, we discuss how the reversibility of light-induced defects depends on (the lack of observable) hydrogen evolution.
Orthorhombic-tetragonal phase coexistence and enhanced piezo-response at room temperature in Zr, Sn, and Hf modified BaTiO3
Authors: Kalyani Ajay Kumar , Brajesh Kumar , Senyshyn Anatoliy , Ranjan Rajeev
Published: June 2014

The effect of Zr, Hf, and Sn in BaTiO3 has been investigated at close composition intervals in the dilute concentration limit. Detailed structural analysis by x-ray and neutron powder diffraction revealed that merely 2 mol. % of Zr, Sn, and Hf stabilizes a coexistence of orthorhombic (Amm2) and tetragonal (P4mm) phases at room temperature. As a consequence, all the three systems show substantial enhancement in the longitudinal piezoelectric coefficient (d33), with Sn modification exhibiting the highest value ∼425 pC/N.
Three dimensional instabilities of an electron scale current sheet in collisionless magnetic reconnection
Authors: Jain Neeraj , Büchner Jörg
Published: June 2014

In collisionless magnetic reconnection, electron current sheets (ECS) with thickness of the order of an electron inertial length form embedded inside ion current sheets with thickness of the order of an ion inertial length. These ECS's are susceptible to a variety of instabilities which have the potential to affect the reconnection rate and/or the structure of reconnection. We carry out a three dimensional linear eigen mode stability analysis of electron shear flow driven instabilities of an electron scale current sheet using an electron-magnetohydrodynamic plasma model. The linear growth rate of the fastest unstable mode was found to drop with the thickness of the ECS. We show how the nature of the instability depends on the thickness of the ECS. As long as the half-thickness of the ECS is close to the electron inertial length, the fastest instability is that of a translational symmetric two-dimensional (no variations along flow direction) tearing mode. For an ECS half thickness sufficiently larger or smaller than the electron inertial length, the fastest mode is not a tearing mode any more and may have finite variations along the flow direction. Therefore, the generation of plasmoids in a nonlinear evolution of ECS is likely only when the half-thickness is close to an electron inertial length.
Characterization of the electrocaloric effect and hysteresis loss in relaxor ferroelectric thin films under alternating current bias fields
Authors: Jia Yanbing , Ju Y. Sungtaek
Published: June 2014

We report characterization and analysis of the frequency-dependent temperature responses in thin films exhibiting the electrocaloric (EC) effect under AC bias fields using a high-precision lock-in technique. The temperature response detected by an embedded thin-film resistance thermometer is analyzed using the steady-periodic solutions of a 3D heat conduction model to extract the equivalent volumetric heat sources/sinks, which represent the combined effects of electrocaloric cooling/heating and hysteresis loss. The dependence of the measured heat source strengths on the bias field frequency and amplitude is consistent with our model prediction and independently measured dielectric properties. The volumetric heating rate due to hysteresis loss is estimated to be as much as 15% of the EC heating/cooling rates for solution-cast relaxor ferroelectric polymer films studied here. Our experimental approach enables a systematic study of the electrocaloric performance of thin films and deleterious impact of hysteresis loss.
Multiscale Spatial Decomposition for Skew-Distributed Data with Parallel Spatial Kernel Smoothing
Authors: Yuan Linwang , Yu Zhaoyuan , Yi Lin , Luo Wen , Chen Shaofei
Published: June 2014

A data-adaptive multiscale spatial decomposition model is proposed to deal with skew-distributed data (eg, population or GDP). Relying on the filtering characteristics according to the bandwidth change of kernel smoothing, the parallel spatial kernel smoothing with different bandwidths is constructed as spatial filter banks for filtering spatial variations at different spatial scales. The filtering residual, a function changing with the spatial scale, is then extracted by parallel spatial kernel smoothing. With a change point detection model based on the second deviation, standard deviation of the residential data is selected for identifying robust significant scales. Then we present the iterative algorithm to extract and remove significant spatial variations at different scales. With well-designed stop criteria, the full hierarchical spatial scale structure in the original spatial process can be adaptively established without assigning the decomposition levels artificially. The computation processes and the statistical and spatial distribution characteristics are demonstrated with case studies of 2003 Chinese population data and GDP data, and the results show that the proposed model is suitable for decomposing the spatial data with spatial heterogeneity. Comparison with the 2D wavelet decomposition suggests that our model has better data-adaptive and shape-preserving ability.
Timing of Speech and Display Affects the Linguistic Mediation of Visual Search
Authors: Chiu Eric M , Spivey Michael J
Published: June 2014

Recent studies have shown that, instead, of a dichotomy between parallel and serial search strategies, in many instances we see a combination of both search strategies utilized. Consequently, computational models and theoretical accounts of visual search processing have evolved from traditional serial-parallel descriptions to a continuum from ‘efficient’ to ‘inefficient’ search. One of the findings, consistent with this blurring of the serial–parallel distinction, is that concurrent spoken linguistic input influences the efficiency of visual search. In our first experiment we replicate those findings using a between-subjects design. Next, we utilize a localist attractor network to simulate the results from the first experiment, and then employ the network to make quantitative predictions about the influence of subtle timing differences of real-time language processing on visual search. These model predictions are then tested and confirmed in our second experiment. The results provide further evidence toward understanding linguistically mediated influences on real-time visual search processing and support an interactive processing account of visual search and language comprehension.
Effects of Using Multiple Hands and Fingers on Haptic Performance in Individuals Who are Blind
Authors: Morash Valerie S , Pensky Allison E Connell , Tseng Steven T W , Miele Joshua A
Published: June 2014

In a previous paper we documented that sighted participants complete haptic tasks faster with two hands and multiple fingers, but that these benefits are task specific. The present study investigates whether these effects are the same for participants who are blind. We compared the performance of fourteen blind participants on seven tactile-map tasks using seven finger conditions. As with sighted participants, blind participants performed all tasks faster with multiple fingers. Line-tracing tasks were faster with fingers added to an already in-use hand, and sometimes when added to the second hand. Local and global search tasks were faster with multiple fingers and two hands. Distance comparison tasks were performed faster with multiple fingers, but not two hands. Lastly, moving in a straight line was faster with multiple fingers. These results reinforce our previous finding that the haptic system performs best when it can exploit the independence of multiple fingers. Furthermore, in every instance that an effect was different between sighted and blind participants, the blind participants benefitted more from two hands or multiple fingers than the sighted participants. This indicates that the blind participants have learned, through experience or training, how to best take advantage of multiple fingers during haptic tasks.
Shifts in biomass and nitrogen allocation of tree seedlings in response to root-zone temperature
Authors: Rogiers Suzy Y. , Smith Jason P. , Holzapfel Bruno P. , Nielsen Gurli L.
Published: June 2014

Root-zone warming of trees can result in an increase in biomass production but the mechanisms for this increase may differ between evergreen and deciduous species. The leaf gas exchange, carbohydrate and nitrogen (N) partitioning of two Australian evergreens, Acacia saligna and Eucalyptus cladocalyx, were compared to the deciduous Populus deltoides and Acer negundo after exposure to cool or warm soil during spring. The warm treatment stimulated aboveground biomass production in all four species; however, the form of this increase was species dependent. Compared with the evergreens, soluble sugars were mobilised from the above- and belowground components to a greater extent in the deciduous species, especially during root-zone warming. Photosynthesis, stomatal conductance and transpiration were increased in the warm soil treatment for the two evergreens and P. deltoides only. In P. deltoides and A. saligna the new fine roots contained greater starch concentrations when grown in warm soil but only in A. negundo was new root growth greater. Compared with the other three species, the leguminous A. saligna contained the highest N and most of this was concentrated in the phyllodes of warmed plants with no apparent mobilisation from the existing biomass. In the other evergreen, E. cladocalyx, the existing leaves and stems were a N source for new growth, while in the two deciduous species N was derived from the woody components and structural roots. These data show that the carbohydrate movement and N partitioning patterns in response to soil warming differ between perennial and deciduous plants and are likely responsible for the different forms of biomass accumulation in each of these species.
Implications of risk attitude and climate change for optimal grassland management: a case study for Switzerland
Authors: Finger Robert , Calanca Pierluigi , Briner Simon
Published: June 2014

We present a bio-economic model by combining a process-based grassland simulation model with an economic decision model that accounts for income risks and yield quality. The model is used to examine optimal nitrogen (N) application rates in a grass–clover system in Switzerland under current and future climatic conditions. Results for present-day climatic conditions suggest that an increase in N inputs has positive effects on yields but also leads to higher yield variability, yield distributions more skewed to the left and therefore higher downside risks. As a result, accounting for farmers’ risk aversion in solving the optimisation problem leads to lower optimal N inputs. Simulations with a climate change scenario that predicts higher temperatures throughout the year and lower rainfall amounts during the growing season indicate higher yields, increasing yield variability, and changes in yield quality. By allowing herbage prices to vary as a function of yield quality, we find overall lower optimal N inputs and more marked effects of risk aversion on optimal N levels under climate change than under present conditions. However, disregarding yield quality in solving the optimisation problem gives higher optimal N inputs under future conditions.
Reflectance indices as nondestructive indicators of the physiological status of Ceratonia siliqua seedlings under varying moisture and temperature regimes
Authors: Osório Júlio , Osório Maria Leonor , Romano Anabela
Published: June 2014

We investigated the use of spectral reflectance techniques to monitor the physiological responses of Ceratonia siliqua L. seedlings exposed to different levels of water availability under normal (25 : 18°C, day : night) and elevated (32 : 21°C, day : night) temperatures. Three spectral reflectance indices (photochemical reflectance index, PRI; water index, WI; red edge position, REP) were measured along with water status, chlorophyll fluorescence and chlorophyll concentration variables in the leaves of well watered, moderately stressed, severely stressed and rehydrated plants under each temperature regime. The PSII effective photochemical efficiency (φ2) and the intrinsic efficiency of open PSII centres (F′v/F′m) correlated significantly with PRI, and these three variables loaded heavily onto the same principal component of a three-factor principal component analysis solution. Water concentration (WC) and the succulence index (SI) were more strongly correlated with WI than either water potential (ΨPD) or relative water content (RWC). Accordingly, WI, WC and SI were combined in the second principal component, and ΨPD and RWC in the third. Our results provide clear evidence for interaction between water availability and temperature in the WI and the PRI response segments of the reflectance curves. Elevated temperature inhibited the recovery of WI spectral segments more than that of the PRI segments in SS plants. REP showed a strongly positive linear relationship with leaf total chlorophyll concentration across all water and temperature treatment combinations. PRI, WI and REP are therefore reliable markers that can be used to monitor φ2, WC and total chlorophyll concentration, respectively, in C. siliqua seedlings under drought and temperature stress.
Effect of biochar on soil respiration in the maize growing season after 5 years of consecutive application
Authors: Lu Ning , Liu Xing-Ren , Du Zhang-Liu , Wang Yi-Ding , Zhang Qing-Zhong
Published: June 2014

The effect of biochar on soil respiration (Rs) over one maize-growing season was studied after 5 years of consecutive application in an intensive cropland in the North China Plain. The experiment was carried out in randomly arranged plots with four treatments being evaluated. Three replications were conducted per treatment: a control plot without biochar addition (CK), biochar incorporated at 4.5 t ha–1 year–1 (BC4.5), biochar incorporated at 9.0 t ha–1 year–1 (BC9.0), and incorporated wheat straw (SR). The Rs was determined throughout the growing season of maize in 2012. Soil temperature and moisture were measured simultaneously at 5 cm depth. The results showed that the seasonal and diurnal variations of Rs in the four different treatments were approximately equal, and there was a positive correlation between Rs and soil temperature. The Rs values of treatments BC4.5 and BC9.0 were significantly lower than of SR but not CK. Significant correlations between Rs and soil temperature and soil moisture were observed. Soil temperature had a stronger effect on Rs than did soil moisture, and Rs was more sensitive to soil temperature in the biochar treatments than in the SR and CK treatments. The application of biochar and straw increased the soil active organic carbon content, but an obvious relationship between Rs and the soil active organic carbon content was not found.
Numerical prediction of size, mass, temperature and trajectory of cylindrical wind-driven firebrands
Authors: Oliveira Luis A. , Lopes António G. , Baliga Bantwal R. , Almeida Miguel , Viegas Domingos X.
Published: June 2014

Mathematical models and numerical solution procedures for predicting the trajectory, oscillation, possible rotation, and mass and size time-evolution of cylindrical wind-driven firebrands are described and discussed. Two test problems and the results, used for validating the mathematical models, are presented. In one, experimental measurements of non-burning cylindrical particles falling in still air are compared to numerical predictions and in the other, predictions of time-evolution of mass and size of stationary burning particles in air flows are compared with experimental results reported in the literature. Results yielded by the proposed models for a demonstration problem involving cylindrical wind-driven firebrands, with the same initial volume, mass and position, but different initial aspect ratios and distinct initial orientations relative to the wind velocity, are then presented. These results show the following: the horizontal distance travelled by the firebrand from release to landing locations is an increasing function of its initial aspect ratio; and the initial orientation of the firebrand, and its subsequent oscillations including possible rotation, have a significant influence on its trajectory, thus it is important to account for them in mathematical models formulated for predicting the spread of fires by spotting.
Daily food intake of free-ranging wild rabbits in semiarid South Australia
Authors: Cooke B. D.
Published: June 2014

Context Although the daily food intake of wild rabbits is broadly known, precise field estimates have not been made. Moreover, regressions based on metabolic body size and food intake of grazing herbivores in general are too imprecise to provide close predictions. Using such values could result in substantial errors when estimating grazing equivalents to sheep or cattle and resultant economic losses, or estimating the numbers of rabbits per hectare based on rates of deposition of faeces. Aim To re-analyse previously collected data on estimated food digestibility and food intake of rabbits, and provide a framework for better estimating economic and conservation losses attributable to wild rabbits. Methods Food intake of wild free-ranging rabbits was calculated from past measurements of water turnover obtained from dilution of injected tritiated water and estimates of the water content and digestibility of the food eaten. Key results During spring, male rabbits were estimated to eat 65.7 ± 12.5 g dry matter per corrected bodyweight (W–0.75) per day and lactating females ate 97.0 ± 19.4 g dry matter W–0.75 day–1. Similar results were obtained on repetition of trials at a second field site and from wild rabbits held in captivity. Conclusions The estimates of food digestibility and intake obtained, although not precise, are an improvement on theoretical expectations alone and help put previously published data in better perspective. Implications Improved estimates of food consumption provide more confidence in estimates of rabbit grazing pressure. Even moderate densities of rabbits (5 rabbits per ha) could remove about half the pasture produced in an average year in Australia’s arid-zone.
Impaired functional communication between the L-type calcium channel and mitochondria contributes to metabolic inhibition in the
mdx
heart
Authors: Viola Helena M. , Adams Abbie M. , Davies Stefan M. K. , Fletcher Susan , Filipovska Aleksandra , Hool Livia C.
Published: June 2014

Significance

Duchenne muscular dystrophy (DMD) is a fatal X-linked disease that results in cardiomyopathy and heart failure. The cardiomyopathy is characterized by cytoskeletal protein disarray, contractile dysfunction, and reduced energy production. The mechanisms for altered energy metabolism are not yet fully clarified. The L-type Ca
2+
channel regulates excitation and contraction in the heart, and can regulate mitochondrial function via the movement of cytoskeletal proteins. Here, we find that myocytes from the murine model of DMD (
mdx
) exhibit impaired communication between the L-type Ca
2+
channel and the mitochondria that results in poor energy production. Morpholino oligomer therapy targeting dystrophin or block of the mitochondrial voltage-dependent anion channel (VDAC) “rescues” metabolic function, indicating that impaired communication between the L-type Ca
2+
channel and VDAC contributes to the cardiomyopathy.
The conservative minimum: historical and transcendent subject
Authors: Özsel Doğancan
Published: June 2014

In this article, I propose a conservative minimum that characterizes conservative thought and differentiates it from non-conservative discourses on society and politics. According to this analysis, conservative arguments justify their agenda of change with reference to a historical and transcendent subject that is commonly (but not always) labelled ‘society’. Classical forms of other main ideologies lack such a conception of collectively created subject that is seen as both historical and transcendent. This subject, and its use as the final source of justification of policy proposals, is therefore a characteristic of conservative thought. All variations of conservatism, including those that seek to preserve the establishment and those that advocate reforms, aim to conserve this historical and transcendent entity. Defining this subject offers a heuristic advantage, as it covers most of the political thoughts and movements that define themselves as conservative. It also highlights a fundamental commonality among very different political styles – ranging from Burkean to revolutionary conservatism – while differentiating this diverse family of discourses from non-conservative discourses. Hence, it furthers our understanding of conservatism.
Singularity structures for noncommutative spaces
Authors: Dave Shantanu , Kunzinger Michael
Published: June 2014

We introduce a (bi)category

S
i
n
g

\mathfrak {Sing}

whose objects can be functorially assigned spaces of distributions and generalized functions. In addition, these spaces of distributions and generalized functions possess intrinsic notions of regularity and singularity analogous to usual Schwartz distributions on manifolds. The objects in this category can be obtained from smooth manifolds, noncommutative spaces, or Lie groupoids. An application of these structures relates the propagation of singularities on a groupoid with that on the base manifold.
Model Choice and Size Distribution: A Bayequentist Approach
Authors: Engler John‐Oliver , Baumgärtner Stefan
Published: June 2014

We propose a new three‐step model‐selection framework for size distributions in empirical data. It generalizes a recent frequentist plausibility‐of‐fit analysis (step 1) and combines it with a relative ranking based on the Bayesian Akaike information criterion (step 2). We enhance these statistical criteria with the additional criterion of microfoundation (step 3), which is to select the size distribution that comes with a dynamic micromodel of size dynamics. A numerical performance test of step 1 shows that our generalization is able to correctly rule out the distribution hypotheses unjustified by the data at hand. We then illustrate our approach and demonstrate its usefulness with a sample of commercial cattle farms in Namibia. In conclusion, the framework proposed here has the potential to reconcile the ongoing debate about size distribution models in empirical data, the two most prominent of which are the Pareto and the log‐normal distribution.
Two exopolyphosphatases with distinct molecular architectures and substrate specificities from the thermophilic green-sulfur bacterium Chlorobium tepidum TLS
Authors: Albi Tomás , Serrano Aurelio
Published: June 2014

The genome of the thermophilic green-sulfur bacteriumChlorobium tepidumTLS possesses two genes encoding putative exopolyphosphatases (PPX; EC 3.6.1.11), namely CT0099 (ppx1, 993 bp) and CT1713 (ppx2, 1557 bp). The predicted polypeptides of 330 and 518 aa residues are Ppx-GppA phosphatases of different domain architectures – the largest one has an extra C-terminal HD domain – which may represent ancient paralogues. Bothppxgenes were cloned and overexpressed inEscherichia coliBL21(DE3). While CtPPX1 was validated as a monomeric enzyme, CtPPX2 was found to be a homodimer. Both PPX homologues were functional, K+-stimulated phosphohydrolases, with an absolute requirement for divalent metal cations and a marked preference for Mg2+. Nevertheless, they exhibited remarkably different catalytic specificities with regard to substrate classes and chain lengths. Even though both enzymes were able to hydrolyse the medium-size polyphosphate (polyP) P13–18(polyP mix with mean chain length of 13–18 phosphate residues), CtPPX1 clearly reached its highest catalytic efficiency with tripolyphosphate and showed substantial nucleoside triphosphatase (NTPase) activity, while CtPPX2 preferred long-chain polyPs (>300 Pi residues) and did not show any detectable NTPase activity. These catalytic features, taken together with the distinct domain architectures and molecular phylogenies, indicate that the two PPX homologues ofChl. tepidumbelong to different Ppx-GppA phosphatase subfamilies that should play specific biochemical roles in nucleotide and polyP metabolisms. In addition, these results provide an example of the remarkable functional plasticity of the Ppx-GppA phosphatases, a family of proteins with relatively simple structures that are widely distributed in the microbial world.
SRST2: Rapid genomic surveillance for public health and hospital microbiology labs
Authors: Inouye Michael , Dashnow Harriet , Raven Lesley , Schultz Mark B. , Pope Bernard J. , Tomita Takehiro , Zobel Justin , Holt Kathryn E.
Published: June 2014

Rapid molecular typing of bacterial pathogens is critical for public health epidemiology, surveillance and infection control, yet routine use of whole genome sequencing (WGS) for these purposes poses significant challenges. Here we present SRST2, a read mapping-based tool for fast and accurate detection of genes, alleles and multi-locus sequence types (MLST) from WGS data. Using >900 genomes from common pathogens, we show SRST2 is highly accurate and outperforms assembly-based methods in terms of both gene detection and allele assignment. Here we have demonstrated the use of SRST2 for microbial genome surveillance in a variety of public health and hospital settings. In the face of rising threats of antimicrobial resistance and emerging virulence amongst bacterial pathogens, SRST2 represents a powerful tool for rapidly extracting clinically useful information from raw WGS data. Source code is available fromhttp://katholt.github.io/srst2/.
Guerrilla‐style Defensive Architecture in Detroit: A Self‐provisioned Security Strategy in a Neoliberal Space of Disinvestment
Authors: Kinder Kimberley
Published: June 2014

Self‐provisioning has long been an important component of urban political economic processes. However, it has recently become a central feature of grassroots urban governance strategies as well. In tumultuous cities of the twenty‐first century, with governments either unwilling or unable to effectively enforce zoning laws, police neighborhoods or manage infrastructure, some householders have begun performing these services instead. This article examines one subset of self‐provisioning practices that has emerged in southwest Detroit where residents have taken steps to secure abandoned housing as a means of exerting social control over their living environment. These actions embody many contradictions and ethical dilemmas, and the intimate scale of action has left the structural production of disinvestment in places like Detroit largely unchecked. Nevertheless, these guerilla‐style spatial interventions have emerged as critically important response strategies helping residents reduce their vulnerability and stabilize their blocks even as other nearby areas continue to experience decline.
THE EFFECTS OF DIRECTED PATROL AND SELF‐INITIATED ENFORCEMENT ON FIREARM VIOLENCE: A RANDOMIZED CONTROLLED STUDY OF HOT SPOT POLICING
Authors: ROSENFELD RICHARD , DECKARD MICHAEL J. , BLACKBURN EMILY
Published: June 2014

Targeted policing has proven effective in reducing serious crime in areas where it is highly concentrated, but the enforcement mechanisms responsible for the success of so‐called hot spots strategies remain poorly understood. This study evaluates the effects of a 9‐month randomized controlled hot spots field experiment on firearm assaults and robberies in St. Louis, Missouri. Thirty‐two firearm violence hot spots were randomly allocated to two treatment conditions and a control condition. Directed patrols were increased in both treatment conditions, whereas the experimental protocol limited other enforcement activity in one of the treatment conditions and increased it in the other. The results from difference‐in‐difference regression analyses indicate that the intervention substantially reduced the incidence of nondomestic firearm assaults, with no evident crime displacement to surrounding areas, to times when the intervention was not active, or to nonfirearm assaults. By contrast, we find no effects of the intervention on firearm robberies. Less definitive results suggest that the certainty of arrests and occupied vehicle checks account for the treatment effects on nondomestic firearm assaults.