bluuebunny/crossref_metadata_2025 huggingface dataset:
Time-resolved soft x-ray spectra from laser-produced Cu plasma
Authors: Cone K. V. , Baldis H. A. , Dunn J. , May M. J. , Purvis M. A. , Schneider M. B. , Scott H. A.
Published: September 2012

The volumetric heating of a thin copper target has been studied with time resolved x-ray spectroscopy. The copper target was heated by a plasma produced using the Lawrence Livermore National Laboratory's Compact Multipulse Terawatt (COMET) laser. A variable spaced grating spectrometer coupled to an x-ray streak camera measured soft x-ray emission (800–1550 eV) from the back of the copper target to characterize the bulk heating of the target. Radiation hydrodynamic simulations were modeled in two-dimensions using the HYDRA code. The target conditions calculated by HYDRA were post-processed with the atomic kinetics code CRETIN to generate synthetic emission spectra. A comparison between the experimental and simulated spectra indicates the presence of specific ionization states of copper and the corresponding electron temperatures and ion densities throughout the laser-heated copper target.
Effect of laser pulse shaping parameters on the fidelity of quantum logic gates
Authors: Zaari Ryan R. , Brown Alex
Published: September 2012

The effect of varying parameters specific to laser pulse shaping instruments on resulting fidelities for the ACNOT1, NOT2, and Hadamard2 quantum logic gates are studied for the diatomic molecule 12C16O. These parameters include varying the frequency resolution, adjusting the number of frequency components and also varying the amplitude and phase at each frequency component. A time domain analytic form of the original discretized frequency domain laser pulse function is derived, providing a useful means to infer the resulting pulse shape through variations to the aforementioned parameters. We show that amplitude variation at each frequency component is a crucial requirement for optimal laser pulse shaping, whereas phase variation provides minimal contribution. We also show that high fidelity laser pulses are dependent upon the frequency resolution and increasing the number of frequency components provides only a small incremental improvement to quantum gate fidelity. Analysis through use of the pulse area theorem confirms the resulting population dynamics for one or two frequency high fidelity laser pulses and implies similar dynamics for more complex laser pulse shapes. The ability to produce high fidelity laser pulses that provide both population control and global phase alignment is attributed greatly to the natural evolution phase alignment of the qubits involved within the quantum logic gate operation.
Ab initio determination of coarse-grained interactions in double-stranded DNA
Authors: Hsu Chia Wei , Fyta Maria , Lakatos Greg , Melchionna Simone , Kaxiras Efthimios
Published: September 2012

We derive the coarse-grained interactions between DNA nucleotides from ab initio total-energy calculations based on density functional theory (DFT). The interactions take into account base and sequence specificity, and are decomposed into physically distinct contributions that include hydrogen bonding, stacking interactions, backbone, and backbone-base interactions. The interaction energies of each contribution are calculated from DFT for a wide range of configurations and are fitted by simple analytical expressions for use in the coarse-grained model, which reduces each nucleotide into two sites. This model is not derived from experimental data, yet it successfully reproduces the stable B-DNA structure and gives good predictions for the persistence length. It may be used to realistically probe dynamics of DNA strands in various environments at the μs time scale and the μm length scale.
Ultra low-resistance palladium silicide Ohmic contacts to lightly doped n-InGaAs
Authors: Yearsley J. D. , Lin J. C. , Hwang E. , Datta S. , Mohney S. E.
Published: September 2012

The formation of shallow, ultra-low resistance, Pd/Si solid-phase regrowth (SPR) ohmic contacts to n-In0.53Ga0.47As epilayers of ND=1×1017 cm−3 and ND=3×1019 cm−3 is demonstrated. The resulting specific contact resistances of 9×10−8 Ω  cm2 and 1.8×10−8 Ω cm2, respectively, are the lowest demonstrated for SPR contacts to n-InGaAs. An optimum Pd/Si atomic ratio of 1.5 is found to be essential to achieving low specific contact resistance. A low-temperature, two-step, rapid thermal annealing process has been employed to activate the InGaAs regrowth process and consistently achieve shallow contacts with minimal lateral diffusion. Transmission electron microscopy is used to substantiate the SPR mechanism of contact formation. For lightly doped epilayers, I-V-T measurements from 77–300 K show that the ohmic behavior is a direct result of the SPR process due to the introduction of excess Si dopant greater than 1019 cm−3 at the regrown InGaAs interface.
Impact of wind generators on distribution feeder reconfiguration
Authors: Tabatabaei Sajad , Niknam Taher
Published: September 2012

This paper presents a new algorithm for multiobjective distribution feeder reconfiguration (DFR) problem, while uncertainties of the load and wind generators are considered in the stochastic framework. In order to take the uncertainties into account, a probabilistic distribution load flow technique is adopted using point estimate method. The proposed multiobjective framework can optimize different objective functions including total power losses and voltage deviations simultaneously. As the result of conflicting behavior of these objective functions, a max-min decision maker is used to model operators’ preferences for trading off between these objectives. In addition, a novel and powerful optimization algorithm based on improved honey bee mating optimization is proposed to handle the multiobjective DFR problem sufficiently. Finally, the proposed framework is applied on two test systems in order to prove its efficiency and feasibility in comparison with the other methods in the area.
Effects of 2 nm size added heterogeneity on non-exponential dielectric response, and the dynamic heterogeneity view of molecular liquids
Authors: Johari G. P. , Khouri J.
Published: September 2012

To investigate how non-exponential response could vary under different conditions, we studied the effects of adding 2 nm size polyhedral oligomeric silsesquioxane (POSS) to diglycidyl ether of bisphenol-A, whose molecules have the same terminal (epoxide) dipoles as the tentacle-like side chains attached to the silsesquioxane core of the POSS molecule. Dielectric relaxation spectra show that, on initial addition, the POSS nano-heterogeneity decreases the non-exponential response parameter β, which is consistent with the dynamic heterogeneity view, but it also decreases the relaxation time τm, which is inconsistent with that view. The variations in β and τm with the composition have a thermal equivalence. Despite the lack of translational diffusion required for dynamic heterogeneity, plastic crystals show non-exponential response and non-Arrhenius dynamics. Measurements of β and τm seem more appropriate than using probe molecules or modeling nonlinear response data as a sum of linear responses for testing the dynamic heterogeneity view. Data on molecular liquid mixtures is not generally consistent with this view, and adding a solute does not always decrease β. Studies of mixtures of different size rigid molecules with identical dipolar groups, including polymers, may be useful for comparing the relative effects of temperature and molecular size on β and τm.
How synaptic weights determine stability of synchrony in networks of pulse-coupled excitatory and inhibitory oscillators
Authors: Kriener Birgit
Published: September 2012

Under which conditions can a network of pulse-coupled oscillators sustain stable collective activity states? Previously, it was shown that stability of the simplest pattern conceivable, i.e., global synchrony, in networks of symmetrically pulse-coupled oscillators can be decided in a rigorous mathematical fashion, if interactions either all advance or all retard oscillation phases (“mono-interaction network”). Yet, many real-world networks—for example neuronal circuits—are asymmetric and moreover crucially feature both types of interactions. Here, we study complex networks of excitatory (phase-advancing) and inhibitory (phase-retarding) leaky integrate-and-fire (LIF) oscillators. We show that for small coupling strength, previous results for mono-interaction networks also apply here: pulse time perturbations eventually decay if they are smaller than a transmission delay and if all eigenvalues of the linear stability operator have absolute value smaller or equal to one. In this case, the level of inhibition must typically be significantly stronger than that of excitation to ensure local stability of synchrony. For stronger coupling, however, network synchrony eventually becomes unstable to any finite perturbation, even if inhibition is strong and all eigenvalues of the stability operator are at most unity. This new type of instability occurs when any oscillator, inspite of receiving inhibitory input from the network on average, can by chance receive sufficient excitatory input to fire a pulse before all other pulses in the system are delivered, thus breaking the near-synchronous perturbation pattern.
Critical analysis of uncertainties during particle filtration
Authors: Badalyan Alexander , Carageorgos Themis , Bedrikovetsky Pavel , You Zhenjiang , Zeinijahromi Abbas , Aji Keyiseer
Published: September 2012

Using the law of propagation of uncertainties we show how equipment- and measurement-related uncertainties contribute to the overall combined standard uncertainties (CSU) in filter permeability and in modelling the results for polystyrene latex microspheres filtration through a borosilicate glass filter at various injection velocities. Standard uncertainties in dynamic viscosity and volumetric flowrate of microspheres suspension have the greatest influence on the overall CSU in filter permeability which excellently agrees with results obtained from Monte Carlo simulations. Two model parameters “maximum critical retention concentration” and “minimum injection velocity” and their uncertainties were calculated by fitting two quadratic mathematical models to the experimental data using a weighted least squares approximation. Uncertainty in the internal cake porosity has the highest impact on modelling uncertainties in critical retention concentration. The model with the internal cake porosity reproduces experimental “critical retention concentration vs velocity”-data better than the second model which contains the total electrostatic force whose value and uncertainty have not been reliably calculated due to the lack of experimental dielectric data.
High-density amorphous ice: A path-integral simulation
Authors: Herrero Carlos P. , Ramírez Rafael
Published: September 2012

Structural and thermodynamic properties of high-density amorphous (HDA) ice have been studied by path-integral molecular dynamics simulations in the isothermal-isobaric ensemble. Interatomic interactions were modeled by using the effective q-TIP4P/F potential for flexible water. Quantum nuclear motion is found to affect several observable properties of the amorphous solid. At low temperature (T = 50 K) the molar volume of HDA ice is found to increase by 6%, and the intramolecular O–H distance rises by 1.4% due to quantum motion. Peaks in the radial distribution function of HDA ice are broadened with respect to their classical expectancy. The bulk modulus, B, is found to rise linearly with the pressure, with a slope ∂B/∂P = 7.1. Our results are compared with those derived earlier from classical and path-integral simulations of HDA ice. We discuss similarities and discrepancies with those earlier simulations.
The effects of neutral gas heating on H mode transition and maintenance currents in a 13.56 MHz planar coil inductively coupled plasma reactor
Authors: Jayapalan Kanesh K. , Chin Oi-Hoong
Published: September 2012

The H mode transition and maintenance currents in a 13.56 MHz laboratory 6 turn planar coil inductively coupled plasma (ICP) reactor are simulated for low pressure argon discharge range of 0.02–0.3 mbar with neutral gas heating and at ambient temperature. An experimentally fitted 3D power evolution plot for 0.02 mbar argon pressure is also shown to visualize the effects of hysteresis in the system. Comparisons between simulation and experimental measurements show good agreement in the pressure range of 0.02–0.3 mbar for transition currents and 0.02–0.1 mbar for maintenance currents only when neutral gas heating is considered. This suggests that neutral gas heating plays a non-negligible role in determining the mode transition points of a rf ICP system.
Roles of polarization force and nonthermal electron on dust-acoustic waves in an inhomogeneous dusty plasma with positively charged dust
Authors: Asaduzzaman M. , Mamun A. A.
Published: September 2012

The influence of polarization force (PF) (arises due to dust density inhomogeneity), nonthermal electrons, and dust density inhomogeneity associated with positively charged dust on linear dust-acoustic (DA) waves in an inhomogeneous unmagnetized dusty plasma are investigated. By taking the normal mode analysis, the dispersion relation in such a non-Maxwellian inhomogeneous plasma is obtained, and that the dispersion properties of the DA waves are significantly modified by the presence of PF and nonthermal electrons. The PF is increased with the increase of nonthermal electrons. It is found that the phase speed of the DA waves is significantly decreased with the presence of PF and nonthermal electrons. The potential associated with the DA waves is de-enhanced with the increase of equilibrium dust number density. The role of positive dust number density on dispersion properties is also shown. The present findings relevant to different scenarios in laboratory and space dusty plasma, such as Martian ionosphere, solar flares, TEXTOR-94 tokamak plasmas, rf excited argon magnetoplasma, etc., can be useful to understand the properties of localized electrostatic disturbances in those dusty plasma system, are also briefly addressed.
Quantum efficiency of intermediate-band solar cells based on non-compensated n-p codoped TiO2
Authors: Wu Fengcheng , Lan Haiping , Zhang Zhenyu , Cui Ping
Published: September 2012

As an appealing concept for developing next-generation solar cells, intermediate-band solar cells (IBSCs) promise to drastically increase the quantum efficiency of photovoltaic conversion. Yet to date, a standing challenge lies in the lack of materials suitable for developing IBSCs. Recently, a new doping approach, termed non-compensated n-p codoping, has been proposed to construct intermediate bands (IBs) in the intrinsic energy band gaps of oxide semiconductors such as TiO2. We explore theoretically the optimal quantum efficiency of IBSCs based on non-compensated n-p codoped TiO2 under two different design schemes. The first preserves the ideal condition that no electrical current be extracted from the IB. The corresponding maximum quantum efficiency for the codoped TiO2 can reach 52.7%. In the second scheme, current is also extracted from the IB resulting in a further enhancement in the maximum efficiency to 56.7%. Our findings also relax the stringent requirement that the IB location be close to the optimum value, making it more feasible to realize IBSCs with high quantum efficiencies.
Simultaneous measurement of gravity acceleration and gravity gradient with an atom interferometer
Authors: Sorrentino F. , Bertoldi A. , Bodart Q. , Cacciapuoti L. , de Angelis M. , Lien Y.-H. , Prevedelli M. , Rosi G. , Tino G. M.
Published: September 2012

We demonstrate a method to measure the gravitational acceleration with a dual cloud atom interferometer; the use of simultaneous atom interferometers reduces the effect of seismic noise on the gravity measurement. At the same time, the apparatus is capable of accurate measurements of the vertical gravity gradient. The ability to determine the gravity acceleration and gravity gradient simultaneously and with the same instrument opens interesting perspectives in geophysical applications.
Superlattice-like electrode for low-power phase-change random access memory
Authors: Lu Yegang , Song Sannian , Song Zhitang , Wu Liangcai , He Aodong , Gong Yuefeng , Rao Feng , Liu Bo
Published: September 2012

Superlattice-like top electrode formed alternately by TiN and W was embedded into phase-change random access memory (PCRAM) with the aim of reducing the power. Ga2Sb4Te3 film is employed as phase change layer. The minimum reset voltage of PCRAM based on superlattice-like electrode was significantly lower than that of one based on the conventional electrode. The set operation can be completed by an electric pulse as short as 5 ns. The superlattice-like-electrode-based PCRAM can be normally operated at 120 °C with endurance up to 1 × 106 cycles. The low thermal conductivity of superlattice-like electrode is responsible for the performance improvement of PCRAM.
Excitation of terahertz radiation by an electron beam in a dielectric lined waveguide with rippled dielectric surface
Authors: Tripathi Deepak , Uma R. , Tripathi V. K.
Published: September 2012

A relativistic electron beam propagating through a dielectric lined waveguide, with ripple on the dielectric surface, excites a free electron laser type instability where ripple acts as a wiggler. The spatial modulation of permittivity in the ripple region couples a terahertz radiation mode to a driven mode of lower phase velocity, where the beam is in Cerenkov resonance with the slow mode. Both the modes grow at the expanse of beam energy. The terahertz frequency increases as the beam velocity increases. The growth rate of the instability goes as one third power of beam density.
Enhanced nonlinear optical response of metal nanocomposite based photonic crystals
Authors: Husaini Saima , Teng Huayu , Menon Vinod M.
Published: September 2012

We demonstrate enhanced nonlinear optical response from a one-dimensional metal nanocomposite based photonic crystal. A three-fold increase in the two photon absorption coefficient was observed for the photonic crystal structure when compared to a single layer of the metal nanocomposite having comparable metal content. The photonic crystal structure also shows a reduction in the optical limiting threshold by a factor of seven. The combination of metal nanoparticles with appropriately designed plasmon resonance in combination with photonic crystal structure provides an attractive approach for developing practical nonlinear optical devices with low thresholds and wide spectral bandwidth.
Thermalized ground state of artificial kagome spin ice building blocks
Authors: Arnalds Unnar B. , Farhan Alan , Chopdekar Rajesh V. , Kapaklis Vassilios , Balan Ana , Papaioannou Evangelos Th. , Ahlberg Martina , Nolting Frithjof , Heyderman Laura J. , Hjörvarsson Björgvin
Published: September 2012

We present a direct magnetic imaging study on the thermal macrospin ordering of artificial kagome spin ice building blocks. Using photoemission electron microscopy, employing x-ray magnetic circular dichroism, we are able to resolve the single domain magnetic nature of the macrospins and determine the states of the combined building block structures. The nano-patterning and material selection allows thermally activated magnetization reversal for the macrospins to occur. The ordering of the macrospins is dominated by the ground state, consistent with a thermal ground state ordering. This work paves the way for the realization of extended artificial spin ice structures exhibiting experimentally accessible thermal behavior.
Equalizing disordered ferroelectrics for diffraction cancellation
Authors: Parravicini Jacopo , Agranat Aharon J. , Conti Claudio , DelRe Eugenio
Published: September 2012

We show how the cross-over effect of dipolar glasses can be used to observe diffraction cancellation in composite ferroelectric samples independently of composition. We are able to selectively frustrate the dielectric anomaly of different compositionally disordered photorefractive ferroelectrics to achieve scale-free optical propagation at one same temperature.
Increase of interface and bulk density of states in amorphous-indium-gallium-zinc-oxide thin-film transistors with negative-bias-under-illumination-stress time
Authors: Gwang Um Jae , Mativenga Mallory , Migliorato Piero , Jang Jin
Published: September 2012

The evolution with time of interface trap density and bulk density of states in amorphous-indium-gallium-zinc-oxide thin-film transistors (TFTs), for negative-bias-under-illumination-stress (NBIS), is traced. Based on the combined analysis of TFT current-voltage and capacitance-voltage characteristics, position of Fermi energy, flat band voltage, interface trap density, and gap state density per unit energy are investigated as function of NBIS time and applied gate voltage. These key parameters help to identify the degradation phenomena responsible for the negative threshold voltage shift caused by NBIS. In particular, the interface trap density becomes more positive; from 0.03 × 1011/cm2 to 0.65 × 1011/cm2, while the gap trap density per unit energy also increases after NBIS, supporting defect creation in the bulk and build-up of positive charge at the gate insulator/active-layer interface as the mechanism responsible for NBIS instability.
Coded aperture imaging of fusion source in a plasma focus operated with pure D2 and a D2-Kr gas admixture
Authors: Springham S. V. , Talebitaher A. , Shutler P. M. E. , Lee S. , Rawat R. S. , Lee P.
Published: September 2012

The coded aperture imaging (CAI) technique has been used to investigate the spatial distribution of DD fusion in a 1.6 kJ plasma focus (PF) device operated in, alternatively, pure deuterium or deuterium-krypton admixture. The coded mask pattern is based on a singer cyclic difference set with 25% open fraction and positioned close to 90° to the plasma focus axis, with CR-39 detectors used to register tracks of protons from the D(d, p)T reaction. Comparing the coded aperture imaging proton images for pure D2 and D2-Kr admixture operation reveals clear differences in size, density, and shape between the fusion sources for these two cases.
Photoproducts of 7-Hydroxycoumarins in Aqueous Solution
Authors: Smith Gerald J. , Weston Roderick J. , Tang Ying , Lu Yinrong , Dyer Jolon M.
Published: September 2012

Near-UV irradiation of aqueous solutions of 7-hydroxy-6-methoxycoumarin (scopoletin) and 6,7-dihydroxycoumarin (esculetin) resulted in the formation of dimers. Substantially greater amounts of the 7-hydroxy-6-methoxycoumarin photodimer were produced compared with that of 6,7-dihydroxycoumarin. Fluorescence spectra indicated that the initial photolytic reaction involves the excited state of the phenolate form of the monomeric coumarin. The electro-spray ionization (ESI) mass spectrum suggested that the major product (with a sodiated quasimolecular ion at m/z 405) from the photolysis of scopoletin in water had formed by oxidative dimerisation and possibly had a 3,3′-bond. A second dimer (with a sodiated quasimolecular ion at m/z 407) was probably a 2 + 2 cyclodimer. This work concluded that photolysis of coumarins in water results in oxidative dimerisation whereas photolysis in the solid state or in organic solvents results in cyclodimerisation. Minor monomeric photoproducts were a dihydroxy-6-methoxycoumarin from 7-hydroxy-6-methoxycoumarin and a trihydroxycoumarin from 6,7-dihydroxycoumarin. During ESI-mass spectrometry (ESI-MS), sodiated quasimolecular ions of the photodimer formed more readily than protonated quasimolecular ions and the sodiated ions did not fragment readily. Protonated quasimolecular ions of the monomeric coumarins formed more readily than their sodiated counterparts and the protonated ions fragmented to create daughter ion spectra that were useful for chemical structural assignment.
Comparative studies on reproductive structures in four amphicarpic tropical Phaseoleae legumes
Authors: Kumar P. Saravana , Lawn R. J. , Bielig L. M.
Published: September 2012

Amphicarpy, an adaptive trait whereby both aerial and underground fruits are formed on the one plant, occurs in several plant taxa, notably the Phaseoleae legumes. Amphicarpic species offer the dual potential benefits of enhanced persistence through their underground seed, combined with ease of harvest of their aerial seed. While amphicarpy has been reported in several endemic Australian tropical legumes, information on the trait is sparse. The objective of the current research was to compare aerial and underground reproductive structures in amphicarpic tropical legumes from four different sub-tribes within the Phaseoleae: three Australian endemic species, Vigna lanceolata (sub-tribe Phaseolinae), Flemingia pauciflora (sub-tribe Cajaninae), and Glycine falcata (sub-tribe Glycininae); and the exotic pasture legume Centrosema rotundifolium (sub-tribe Clitoriinae). As far as we know, this report of amphicarpy in F. pauciflora is the first record of the trait in a member of the Cajaninae. Descriptions, drawings, and photographs of the morphology and anatomy of the aerial and underground fruiting structures were documented. In general, the aerial flowers in all genotypes studied were chasmogamous, allowing at least some opportunity for outcrossing. In contrast, the underground flowers were invariably much reduced, with a small, non-pigmented corolla enclosed in much-reduced, scale-like sepals. Nonetheless, anthers and viable pollen were observed in the underground flowers in all four species. With the exception of C. rotundifolium, the underground fruiting structures formed on rhizomes which initially arose either from the underground cotyledonary nodes or, in the case of G. falcata, which is epigeal, from the junction of the stem and taproot. The rhizomes gave rise to ramets when they emerged at the surface or from holes in pot bases. The V. lanceolata accessions also produced fleshy tubers which gave rise to rhizomes, especially in subsequent years. In C. rotundifolium, the geocarpic structures arose on specialised, fleshy, geotropic stems that grew down from the stoloniferous stems. In all species, the number of seeds per underground pod was fewer than in the aerial pods, and the underground seeds were invariably larger, although the extent differed between legume genotypes. There was no evidence of effects on growth or development depending on whether plants were grown from aerial or underground seeds. Some of the adaptive and agronomic implications of the key findings are discussed. In particular, it is argued that amphicarpy in the Australian species is an adaptation to seed predation, and to spatially heterogeneous inland soils.
Climate - fire interactions during the Holocene: a test of the utility of charcoal morphotypes in a sediment core from the boreal region of north-western Ontario (Canada)
Authors: Moos Melissa T. , Cumming Brian F.
Published: September 2012

Charcoal accumulation rates and fire-return intervals were calculated from total charcoal and charcoal morphotypes over the Holocene, from a well-dated sediment core from Lake 239 located in north-western Ontario, and compared with previously published independent climate reconstructions. Both total and morphotype analysis show a two-to-three fold increase in accumulation rates in the early-to-mid Holocene (range: 1 to 6 pieces cm–2 year–1) compared with the early and late Holocene (range: 0 to 2 pieces cm–2 year–1). Fire-return intervals and fire frequencies calculated during these periods, based on peak analysis, showed very different trends. The fire-return interval based on Type M charcoal, a morphotype associated with primary charcoal deposition, was high during the early and late Holocene, and low from ~7500 to 4000 cal year BP, with high inferred fire frequency during the warm mid-Holocene (~12.5 fires per 1000 years), compared with <5 fires per 1000 years over the rest of the Holocene, whereas fire-return interval and fire frequency based on total charcoal did not show patterns consistent with climate. These results suggest that a two- to three-fold increase in fire frequency would not be unexpected in the future under a predicted warmer climate.
Mid-season physical fitness profile of interagency hotshot firefighters
Authors: Sell Katie M. , Livingston Bequi
Published: September 2012

The purpose of this study was to generate a physical fitness profile of an interagency hotshot crew mid-way through the wildland fire season. Twenty interagency hotshot crew firefighters completed measures of body composition, aerobic fitness, hamstring flexibility, muscular strength, explosive strength and muscular endurance. Firefighters exhibited 12.9 ± 2.3% body fat, scored 9.4 ± 0.4 min on the 1.5-mile (2.41 km) run, 48.8 ± 5.3 cm on the sit-and-reach test, 63.7 ± 8.2 kg and 58.7 ± 7.6 kg for right- and left-hand grip strength, and 55.9 ± 9.9 cm on the vertical jump. Firefighters scored 45 ± 12 for push-ups, 60 ± 6 for sit-ups and 13 ± 4 for pull-ups. All fitness scores were at or above average compared with sex- and age-corrected norms, and interagency hotshot crew-specific recommendations for completion of the 1.5-mile run, push-up, sit-up and pull-up tests. Although these data provide a cross-sectional gauge of mid-season fitness parameters, it is unclear how the occupational stresses of the job alter common measures of fitness in interagency hotshot crews. Future research may help highlight seasonal fluctuations in physical fitness, and the effect of physical fitness training on fitness parameters throughout the fire season.
The adaptive capacity of New Zealand communities to wildfire
Authors: Jakes Pamela J. , Langer E. R. (Lisa)
Published: September 2012

When we think of natural disasters in New Zealand, we tend to think of earthquakes or volcanic eruptions. However, a series of events is placing New Zealand communities at greater risk of wildfire. In a case study of a rural New Zealand community that experienced wildfire, process elements such as networks and relationships among locals, development and application of local knowledge and experience, and access to and application of expert knowledge and institutional capacity helped build adaptive capacity for disasters.
Microbial oceanography of anoxic oxygen minimum zones
Authors: Ulloa Osvaldo , Canfield Donald E. , DeLong Edward F. , Letelier Ricardo M. , Stewart Frank J.
Published: September 2012

Vast expanses of oxygen-deficient and nitrite-rich water define the major oxygen minimum zones (OMZs) of the global ocean. They support diverse microbial communities that influence the nitrogen economy of the oceans, contributing to major losses of fixed nitrogen as dinitrogen (N
2
) and nitrous oxide (N
2
O) gases. Anaerobic microbial processes, including the two pathways of N
2
production, denitrification and anaerobic ammonium oxidation, are oxygen-sensitive, with some occurring only under strictly anoxic conditions. The detection limit of the usual method (Winkler titrations) for measuring dissolved oxygen in seawater, however, is much too high to distinguish low oxygen conditions from true anoxia. However, new analytical technologies are revealing vanishingly low oxygen concentrations in nitrite-rich OMZs, indicating that these OMZs are essentially anoxic marine zones (AMZs). Autonomous monitoring platforms also reveal previously unrecognized episodic intrusions of oxygen into the AMZ core, which could periodically support aerobic metabolisms in a typically anoxic environment. Although nitrogen cycling is considered to dominate the microbial ecology and biogeochemistry of AMZs, recent environmental genomics and geochemical studies show the presence of other relevant processes, particularly those associated with the sulfur and carbon cycles. AMZs correspond to an intermediate state between two “end points” represented by fully oxic systems and fully sulfidic systems. Modern and ancient AMZs and sulfidic basins are chemically and functionally related. Global change is affecting the magnitude of biogeochemical fluxes and ocean chemical inventories, leading to shifts in AMZ chemistry and biology that are likely to continue well into the future.
Effects of Multiple Electrical Field Exposures on Cyprinid Embryo Survival
Authors: Nutile Sam , Amberg Jon J. , Sepúlveda María S. , Goforth Reuben R.
Published: September 2012

The effects of electricity on fish embryo survival during sampling events have been previously researched, demonstrating that survival is affected by voltage gradient, current type, exposure duration, developmental stage, and egg diameter. However, the effects of multiple electrical field exposures on fish embryos, such as during sampling depletions, have not been investigated. We conducted multiple electrical field exposures over a range of voltage gradients and resting intervals to determine potential effects on zebrafish Danio rerio embryos during epiboly. However, multiple electrical field exposures had no effect on zebrafish embryo survival, and the only factor to significantly decrease survival regardless of the number of exposures was a voltage gradient of 16 V/cm. Since zebrafish are widely used as model cyprinids, our results suggest that multiple electrical field exposures during electrofishing depletions are not likely to significantly increase cyprinid fish embryo mortality.

Received March 1, 2012; accepted May 23, 2012
Doubly dispossessed by accumulation: Egyptian fishing communities between enclosed lakes and a rising sea
Authors: Malm Andreas , Esmailian Shora
Published: September 2012

In a corner of the Egyptian revolutionary drama, the fisherfolk of the northern Nile Delta have begun to organise. They suffer an indicative predicament. The two great lagoons of Borullus and Manzala have largely been enclosed by fish farms as the Mubarak regime sought to expand Egypt's aquaculture industry. On the other hand, the sea is threatening to submerge the ground on which the very same fishing communities are based. How can we understand the pinch in which they find themselves? This article questions the sustainability of the Egyptian aquaculture miracle, examines the likely impacts of sea level rise on the communities north of Borullus and Manzala, and seeks to conceptualise the dialectic between the two processes. While the fisherfolk prepare to fight against the encroaching farms, however, there is little on the horizon in the way of struggle against the other, perhaps even more dangerous side of the squeeze.

[Doublement dépossédés par l'accumulation: les communautés des pêcheurs égyptiens entre les lacs fermés et une mer montante.] Dans un coin du drame révolutionnaire égyptien, la communauté des pêcheurs dans le Nord du Delta du Nil a commencé à s'organiser. Elle souffre d'une situation à titre indicatif. Les deux grandes lagunes de Borullus et de Manzala ont été en grande partie entourées par les exploitations piscicoles, comme le régime de Moubarak a cherché à élargir l'industrie de l'aquaculture égyptienne. D'autre part, la mer menace de submerger le terrain sur lequel ces mêmes communautés de pêche sont établies. Comment pouvons-nous comprendre le malaise dans lequel ils se trouvent? Cet article évoque la question du miracle de la durabilité de l'aquaculture égyptienne, examine les effets probables de l'élévation du niveau de la mer au nord des communautés de Borullus et de Manzala, et cherche à établir un concept dialectique entre les deux processus. Alors que les pêcheurs se préparent à lutter contre les exploitations agricoles contrariantes, il ya cependant peu de marge à l'horizon sur la façon de lutter contre l'autre – peut-être même le plus dangereux – côté de la compression.

Mots-clés: L'Egypte; les communautés de pêche; l'élévation du niveau de la mer; l'aquaculture; l'accumulation par dépossession; la révolution
The equations of Rees algebras of equimultiple ideals of deviation one
Authors: Muiños Ferran , Planas-Vilanova Francesc
Published: September 2012

We describe the equations of the Rees algebra

R

(
I
)

\mathbf {R}(I)

of an equimultiple ideal

I
I

of deviation one provided that

I
I

has a reduction generated by a regular sequence

x
1

,
…
,

x
s

x_1,\ldots ,x_s

such that the initial forms

x
1
∗

,
…
,

x

s
−
1

∗

x_1^*,\ldots ,x_{s-1}^*

are a regular sequence in the associated graded ring. In particular, we prove that there is a single equation of maximum degree in a minimal generating set of the equations of

R

(
I
)

\mathbf {R}(I)

, which recovers some previous known results.
Comparison of Nutritional Compounds in Premature Green and Mature Yellow Whole Wheat in Korea
Authors: Yang Dan , Shin Jung‐Ah , Gan Lu‐Jing , Zhu Xue‐Mei , Hong Soon‐Taek , Sung Chang‐Keun , Cho Jin‐Woong , Ku Ja‐Hyeong , Lee Ki‐Teak
Published: September 2012

Until now few comparisons of nutritional compounds in premature green and mature yellow wheat have been reported. In this study, the contents of amino acids, vitamins, mineral compounds, phytosterols, and fatty acids as well as the proximate composition of premature green and mature yellow wheat were investigated. Premature green wheat had lower protein content (12.0 g/100 g db) and higher dietary fiber content (19.3 g/100 g db) than mature yellow wheat (13.6 and 14.3 g/100 g db for protein and dietary fiber, respectively). Despite a small difference in total amino acids, protein in premature wheat had a significantly greater proportion of essential amino acids: 16.1, 39.9, and 32.7 mg/g of protein for methionine, lysine, and threonine, respectively. Furthermore, the protein digestibility‐corrected amino acid scores of whole grain premature green and mature yellow wheat were 62.8 and 46.4, respectively, showing significant difference (P < 0.05). Total fatty acids content was 2.66 g/100 g db for premature green wheat and 2.21 g/100 g db for mature yellow wheat. Vitamin C, β‐carotene (provitamin A), α‐ and γ‐tocopherol, and niacin were the major vitamins in premature green wheat, whereas vitamin C and β‐carotene were not detected in mature yellow wheat. The results obtained indicated that premature green wheat has potential for the human diet because of its desirable nutritional value.
Dramatic Change in Citrus tristeza virus Populations in the Dominican Republic
Authors: Matos Luis A. , Hilf Mark E. , Cayetano Xiomara A. , Feliz Andrea O. , Harper Scott J. , Folimonova Svetlana Y.
Published: September 2012

Citrus tristeza virus (CTV) is the most destructive viral pathogen of citrus and has been an important concern for the citrus industry in the Dominican Republic. Earlier studies documented widespread distribution of mild isolates of the T30 genotype, which caused no disease in the infected trees, and a low incidence of isolates of the VT and T3 genotypes, which were associated with economically damaging decline and stem-pitting symptoms in sweet orange and Persian lime, the two major citrus varieties grown in the Dominican Republic. In light of the dramatic increase in the number of severely diseased citrus trees throughout the country over the last decade, suggesting that field populations of CTV have changed, we examined the CTV pathosystem in the Dominican Republic to assess the dynamics of virus populations. In this work, we characterized the molecular composition of 163 CTV isolates from different citrus-growing regions. Our data demonstrate a dramatic change in CTV populations, with the VT genotype now widely disseminated throughout the different regions and with the presence of two new virus genotypes, T36 and RB. Multiple infections of trees resulted in development of complex virus populations composed of different genotypes.
Genetic Variation of Wheat streak mosaic virus in the United States Pacific Northwest
Authors: Robinson Megan D. , Murray Timothy D.
Published: September 2012

Wheat streak mosaic virus (WSMV), the cause of wheat streak mosaic, is a widespread and damaging pathogen of wheat. WSMV is not a chronic problem of annual wheat in the United States Pacific Northwest but could negatively affect the establishment of perennial wheat, which is being developed as an alternative to annual wheat to prevent soil erosion. Fifty local isolates of WSMV were collected from 2008 to 2010 near Lewiston, ID, Pullman, WA, and the United States Department of Agriculture Central Ferry Research Station, near Pomeroy, WA to determine the amount of genetic variation present in the region. The coat protein gene from each isolate was sequenced and the data subjected to four different methods of phylogenetic analyses. Two well-supported clades of WSMV were identified. Isolates in clade I share sequence similarity with isolates from Central Europe; this is the first report of isolates from Central Europe being reported in the United States. Isolates in clade II are similar to isolates originating from Australia, Argentina, and the American Pacific Northwest. Nine isolates showed evidence of recombination and the same two well-supported clades were observed when recombinant isolates were omitted from the analysis. More polymorphic sites, parsimony informative sites, and increased diversity were observed in clade II than clade I, suggesting more recent establishment of the virus in the latter. The observed diversity within both clades could make breeding for durable disease resistance in perennial wheat difficult if there is a differential response of WSMV resistance genes to isolates from different clades.
Recapitulating tumour microenvironment in chitosan–gelatin three-dimensional scaffolds: an improvedin vitrotumour model
Authors: Arya Neha , Sardana Viren , Saxena Meera , Rangarajan Annapoorni , Katti Dhirendra S.
Published: September 2012

Owing to the reduced co-relationship between conventional flat Petri dish culture (two-dimensional) and the tumour microenvironment, there has been a shift towards three-dimensional culture systems that show an improved analogy to the same. In this work, an extracellular matrix (ECM)-mimicking three-dimensional scaffold based on chitosan and gelatin was fabricated and explored for its potential as a tumour model for lung cancer. It was demonstrated that the chitosan–gelatin (CG) scaffolds supported the formation of tumoroids that were similar to tumours grownin vivofor factors involved in tumour-cell–ECM interaction, invasion and metastasis, and response to anti-cancer drugs. On the other hand, the two-dimensional Petri dish surfaces did not demonstrate gene-expression profiles similar to tumours grownin vivo. Further, the three-dimensional CG scaffolds supported the formation of tumoroids, using other types of cancer cells such as breast, cervix and bone, indicating a possible wider potential forin vitrotumoroid generation. Overall, the results demonstrated that CG scaffolds can be an improvedin vitrotool to study cancer progression and drug screening for solid tumours.
Fluctuating noise drives Brownian transport
Authors: Hasegawa Yoshihiko , Arita Masanori
Published: September 2012

The transport properties of Brownian ratchet were studied in the presence of stochastic intensity noise in both overdamped and underdamped regimes. In the overdamped case, an analytical solution using the matrix-continued fraction method revealed the existence of a maximum current when the noise intensity fluctuates on intermediate timescale regions. Similar effects were observed for the underdamped case by Monte Carlo simulations. The optimal time-correlation for Brownian transport coincided with the experimentally observed time-correlation of the extrinsic noise in
Escherichia coli
gene expression and implied the importance of environmental noise for molecular mechanisms.
Multiple nuclear genes and retroposons support vicariance and dispersal of the palaeognaths, and an Early Cretaceous origin of modern birds
Authors: Haddrath Oliver , Baker Allan J.
Published: September 2012

The origin and timing of the diversification of modern birds remains controversial, primarily because phylogenetic relationships are incompletely resolved and uncertainty persists in molecular estimates of lineage ages. Here, we present a species tree for the major palaeognath lineages using 27 nuclear genes and 27 archaic retroposon insertions. We show that rheas are sister to the kiwis, emu and cassowaries, and confirm ratite paraphyly because tinamous are sister to moas. Divergence dating using 10 genes with broader taxon sampling, including emu, cassowary, ostrich, five kiwis, two rheas, three tinamous, three extinct moas and 15 neognath lineages, suggests that three vicariant events and possibly two dispersals are required to explain their historical biogeography. The age of crown group birds was estimated at 131 Ma (95% highest posterior density 122–138 Ma), similar to previous molecular estimates. Problems associated with gene tree discordance and incomplete lineage sorting in birds will require much larger gene sets to increase species tree accuracy and improve error in divergence times. The relatively rapid branching within neoaves pre-dates the extinction of dinosaurs, suggesting that the genesis of the radiation within this diverse clade of birds was not in response to the Cretaceous–Paleogene extinction event.
Strigolactones Are Involved in Root Response to Low Phosphate Conditions in Arabidopsis
Authors: Mayzlish-Gati Einav , De-Cuyper Carolien , Goormachtig Sofie , Beeckman Tom , Vuylsteke Marnik , Brewer Philip B. , Beveridge Christine A. , Yermiyahu Uri , Kaplan Yulia , Enzer Yael , Wininger Smadar , Resnick Natalie , Cohen Maja , Kapulnik Yoram , Koltai Hinanit
Published: September 2012

Strigolactones (SLs) are plant hormones that suppress lateral shoot branching, and act to regulate root hair elongation and lateral root formation. Here, we show that SLs are regulators of plant perception of or response to low inorganic phosphate (Pi) conditions. This regulation is mediated by MORE AXILLARY GROWTH2 (MAX2) and correlated with transcriptional induction of the auxin receptor TRANSPORT INHIBITOR RESPONSE1 (TIR1). Mutants of SL signaling (max2-1) or biosynthesis (max4-1) showed reduced response to low Pi conditions relative to the wild type. In max4-1, but not max2-1, the reduction in response to low Pi was compensated by the application of a synthetic strigolactone GR24. Moreover, AbamineSG, which decreases SL levels in plants, reduced the response to low Pi in the wild type, but not in SL-signaling or biosynthesis mutants. In accordance with the reduced response of max2-1 to low Pi relative to the wild type, several phosphate-starvation response and phosphate-transporter genes displayed reduced induction in max2-1, even though Pi content in max2-1 and the wild type were similar. Auxin, but not ethylene, was sufficient to compensate for the reduced max2-1 response to low Pi conditions. Moreover, the expression level of TIR1 was induced under low Pi conditions in the wild type, but not in max2-1. Accordingly, the tir1-1 mutant showed a transient reduction in root hair density in comparison with the wild type under low Pi conditions. Therefore, we suggest that the response of plants to low Pi is regulated by SLs; this regulation is transmitted via the MAX2 component of SL signaling and is correlated with transcriptional induction of the TIR1 auxin receptor.