bluuebunny/crossref_metadata_2025 huggingface dataset:
Theory of magnetic fluid heating with an alternating magnetic field with temperature dependent materials properties for self-regulated heating
Authors: Ondeck C. L. , Habib A. H. , Ohodnicki P. , Miller K. , Sawyer C. A. , Chaudhary P. , McHenry M. E.
Published: April 2009

Magnetic nanoparticles (MNP) offer promise for local hyperthermia, thermoablative cancer therapy and microwave curing of polymers. Rosensweig's theory predicts that particle size dependence on RF magnetic heating of ferrofluids is chiefly determined by magnetic moment, magnetic anisotropy, and the viscosity of the fluid. Since relaxation times are thermally activated and material parameters can have strong T dependences, heating rates peak at a certain temperature. We extend the model to include the T dependence of the magnetization and anisotropy using mean field theory and literature reported T dependences of selected fluids considered for biomedical applications. We model materials with Curie temperatures near room temperature for which the magnetic properties are strongly T dependent to address the problem of self-regulated heating of ferrofluids.
Pulsed laser deposited tetrahedral amorphous carbon with high sp3 fractions and low optical bandgaps
Authors: Miyajima Y. , Henley S. J. , Adamopoulos G. , Stolojan V. , Garcia-Caurel E. , Drévillon B. , Shannon J. M. , Silva S. R. P.
Published: April 2009

Amorphous carbon films with sp3 bonded carbon fractions over 70% are deposited by pulsed laser deposition. However, the optical bandgap obtained from optical transmittance and spectroscopic ellipsometry analysis shows the values to be below 1.0 eV. A wide range of measurements such as electron energy loss spectroscopy, visible Raman, spectroscopic ellipsometry, optical transmittance, and electrical characterization are performed to elucidate the bonding configurations that dictate microstructural, optical and electrical properties, and their linkage to band structure changes. It is found that stress-induced electronic localized states play an important role in the physical properties of the films deposited. The optical bandgap is shown not to be a good measure of the electrical bandgap, especially for high electric field conduction in these tetrahedral amorphous carbon films.
Grazing exit versus grazing incidence geometry for x-ray absorption near edge structure analysis of arsenic traces
Authors: Meirer F. , Pepponi G. , Streli C. , Wobrauschek P. , Zoeger N.
Published: April 2009

In the presented study the grazing exit x-ray fluorescence was tested for its applicability to x-ray absorption near edge structure analysis of arsenic in droplet samples. The experimental results have been compared to the findings of former analyses of the same samples using a grazing incidence (GI) setup to compare the performance of both geometries. Furthermore, the investigations were accomplished to gain a better understanding of the so called self-absorption effect, which was observed and investigated in previous studies using a GI geometry. It was suggested that a normal incidence-grazing-exit geometry would not suffer from self-absorption effects in x-ray absorption fine structure (XAFS) analysis due to the minimized path length of the incident beam through the sample. The results proved this assumption and in turn confirmed the occurrence of the self-absorption effect for GI geometry. Due to its lower sensitivity it is difficult to apply the GE geometry to XAFS analysis of trace amounts (few nanograms) of samples but the technique is well suited for the analysis of small amounts of concentrated samples.
Forward and inverse cascades in decaying two-dimensional electron magnetohydrodynamic turbulence
Authors: Wareing C. J. , Hollerbach R.
Published: April 2009

Electron magnetohydrodynamic (EMHD) turbulence in two dimensions is studied via high-resolution numerical simulations with a normal diffusivity. The resulting energy spectra asymptotically approach a k−5/2 law with increasing RB, the ratio of the nonlinear to linear time scales in the governing equation. No evidence is found of a dissipative cutoff, consistent with nonlocal spectral energy transfer. Dissipative cutoffs found in previous studies are explained as artificial effects of hyperdiffusivity. Relatively stationary structures are found to develop in time, rather than the variability found in ordinary or MHD turbulence. Further, EMHD turbulence displays scale-dependent anisotropy with reduced energy transfer in the direction parallel to the uniform background field, consistent with previous studies. Finally, the governing equation is found to yield an inverse cascade, at least partially transferring magnetic energy from small to large scales.
Solvent dependent structural perturbations of chemical reaction intermediates visualized by time-resolved x-ray diffraction
Authors: Vincent Jonathan , Andersson Magnus , Eklund Mattias , Wöhri Annemarie B. , Odelius Michael , Malmerberg Erik , Kong Qingyu , Wulff Michael , Neutze Richard , Davidsson Jan
Published: April 2009

Ultrafast time-resolved wide angle x-ray scattering from chemical reactions in solution has recently emerged as a powerful technique for determining the structural dynamics of transient photochemical species. Here we examine the structural evolution of photoexcited CH2I2 in the nonpolar solvent cyclohexane and draw comparisons with a similar study in the polar solvent methanol. As with earlier spectroscopic studies, our data confirm a common initial reaction pathway in both solvents. After photoexcitation, CH2I2 dissociates to form CH2I⋅+I⋅. Iodine radicals remaining within the solvent cage recombine with a nascent CH2I⋅ radical to form the transient isomer CH2I−I, whereas those which escape the solvent cage ultimately combine to form I2 in cyclohexane. Moreover, the transient isomer has a lifetime approximately 30 times longer in the nonpolar solvent. Of greater chemical significance is the property of time-resolved wide angle x-ray diffraction to accurately determine the structure of the of CH2I−I reaction intermediate. Thus we observe that the transient iodine-iodine bond is 0.07 Å±0.04 Å shorter in cyclohexane than in methanol. A longer iodine-iodine bond length for the intermediate arises in methanol due to favorable H-bond interaction with the polar solvent. These findings establish that time-resolved x-ray diffraction has sufficient sensitivity to enable solvent dependent structural perturbations of transient chemical species to be accurately resolved.
Using He droplets for measurements of interconversion enthalpy of conformers in 2-chloroethanol
Authors: Skvortsov Dmitry S. , Vilesov Andrey F.
Published: April 2009

2-chloroethanol molecules having temperature from 300 to 600 K have been captured by helium droplets and the infrared spectra of the O–H and C–H stretching bands of the embedded molecules have been obtained. The intensity ratio of the bands due to trans and gauche conformers of the molecules follows the Arrhenius dependence, giving the enthalpy of conformers interconversion of 1.1 kcal/mol. It is concluded that the abundance ratio of the conformers, which are at equilibrium in the gas phase, remains unchanged upon the rapid cooling of the molecules in the helium droplets.
On the relation between time-dependent and variational density functional theory approaches for the determination of excitation energies and transition moments.
Authors: Ziegler Tom , Seth Michael , Krykunov Mykhaylo , Autschbach Jochen , Wang Fan
Published: April 2009

It is shown that it is possible to derive the basic eigenvalue equation of adiabatic time-dependent density functional theory within the Tamm–Dancoff approximation (TD-DFT/TD) from a variational principle. The variational principle is applied to the regular Kohn–Sham formulation of DFT energy expression for a single Slater determinant and leads to the same energy spectrum as TD-DFT/TD. It is further shown that this variational approach affords the same electric and magnetic transition moments as TD-DFT/TD. The variational scheme can also be applied without the Tamm–Dancoff approximation. Practical implementations of TD-DFT are limited to second order response theory which introduces errors in transition energies for charge transfer and Rydberg excitations. It is indicated that higher order terms can be incorporated into the variational approach. It is also discussed how the current variational method is related to traditional DFT schemes based on variational principles such as ΔSCF-DFT, and how they can be combined.
A theoretical investigation on the spectrum of the Ar trimer for high rotational excitations
Authors: Márquez-Mijares M. , Pérez de Tudela R. , González-Lezana T. , Roncero O. , Miret-Artés S. , Delgado-Barrio G. , Villarreal P. , Baccarelli I. , Gianturco F. A. , Rubayo-Soneira J.
Published: April 2009

A detailed study of the rovibrational spectrum of the Ar trimer is performed by means of an exact hyperspherical coordinate (HC) method and a variational approach based on distributed Gaussian functions (DGFs) to describe the interparticle distances. The good agreement observed between the energy levels obtained with both procedures for high values of the total angular momentum (J=15 and 20) reveals the quality of the DGF method to describe the rotation of the title system. Rotational constants for the lowest bound states, obtained as averages for each vibrational state, have been obtained and compared to previous results. A detailed analysis of density probability functions obtained by means of the HC approach for rovibrational states at J=0 and 20 shows close similitudes thus supporting the vibration-rotation separation adopted within the DGF scheme for the Ar3 system.
Quantum densities of states of fluxional polyatomic systems from a superposition approximation
Authors: Calvo F. , Parneix P. , Basire M.
Published: April 2009

The superposition method is used to calculate quantum densities of states of polyatomic systems with multiple isomeric structures. For each isomer, anharmonicities are included rigorously using a Dunham expansion of the vibrational energy levels and short exchange Monte Carlo simulations are used to compute the individual quantum densities of states. The method is applied to the computation of thermodynamical properties of the Ar13 and Ne13 clusters. The canonical heat capacities are found in very satisfactory agreement with the predictions of quantum or semiclassical sampling methods.
An iterative curve fitting method for accurate calculation of quality factors in resonators
Authors: Naeli Kianoush , Brand Oliver
Published: April 2009

A new method for eliminating the noise effect in interpreting the measured magnitude transfer characteristic of a resonator, in particular in extracting the Q-factor, is proposed and successfully tested. In this method the noise contribution to the measured power spectral density of resonator is iteratively excluded through a sequence of least-square curve fittings. The advantage of the presented method becomes more tangible when the signal to noise power ratio (SNR) is close to unity. A set of experiments for a resonant cantilever vibrating at different amplitudes has shown that when SNR is less than 10, the calculation results of conventional methods in extracting the Q-factor, i.e., the 3 dB bandwidth and single least-square curve fit, exhibit significant deviations from the actual Q-factor, while the result of the proposed iterative method remains in 5% margin of error even for a SNR of unity. This method is especially useful when no specific data is available about the measurement noise, except the assumption that the noise spectral density is constant over the measured bandwidth.
Femtosecond pump-probe studies of actinic-wavelength dependence in aqueous chlorine dioxide photochemistry
Authors: Bixby Teresa J. , Bolinger Joshua C. , Patterson Joshua D. , Reid Philip J.
Published: April 2009

The actinic or photolysis-wavelength dependence of aqueous chlorine dioxide (OClO) photochemistry is investigated using femtosecond pump-probe spectroscopy. Following photoexcitation at 310, 335, and 410 nm the photoinduced evolution in optical density is measured from the UV to the near IR. Analysis of the optical-density evolution illustrates that the quantum yield for atomic chlorine production (ΦCl) increases with actinic energy, with ΦCl=0.16±0.02 for 410 nm excitation and increasing to 0.25±0.01 and 0.54±0.10 for 335 and 310 nm excitations, respectively. Consistent with previous studies, the production of Cl occurs through two channels, with one channel corresponding to prompt (<5 ps) Cl formation and the other corresponding to the thermal decomposition of ClOO formed by OClO photoisomerization. The partitioning between Cl production channels is dependent on actinic energy, with prompt Cl production enhanced with an increase in actinic energy. Limited evidence is found for enhanced ClO production with an increase in actinic energy. Stimulated emission and excited-state absorption features associated with OClO populating the optically prepared A22 surface decrease with an increase in actinic energy suggesting that the excited-state decay dynamics are also actinic energy dependent. The studies presented here provide detailed information on the actinic-wavelength dependence of OClO photochemistry in aqueous solution.
Magnetophotoluminescence properties of Co-doped ZnO nanorods
Authors: Lin C. Y. , Wang W. H. , Lee C.-S. , Sun K. W. , Suen Y. W.
Published: April 2009

We present the detailed experimental results of the magnetic and optical properties of cobalt doped ZnO nanorods, especially the temperature and magnetic field dependence of photoluminescence up to 14 T. The Raman measurements indicate that our Co-doped ZnO nanorods have the same lattice constant as crystalline bulk ZnO. Sharp luminescence peaks centered at around 670 nm were observed at low temperature and their intensity decreased with increasing magnetic field. The luminescence peaks were attributed to d-d transitions in the Ligand field from the doped Co ions. We also observed a diamagnetic shift at a temperature of 1.5 K when the magnetic field was scanned from 0 to 14 T. The exciton radius of the Co-doped ZnO nanorods was deduced from the magnetophotoluminescence results.
Fabrication of anatase precipitated glass-ceramics possessing high transparency
Authors: Masai Hirokazu , Toda Tatsuya , Takahashi Yoshihiro , Fujiwara Takumi
Published: April 2009

Transparent anatase precipitated glass-ceramics were fabricated using ZnO as a component. The particle size of precipitated anatase is several nanometers enough to possess high transparency. The preparation of the Bi-free transparent TiO2 glass-ceramic was attained by substitution of two different kinds of oxides for bismuth oxide. It is also noteworthy that we have demonstrated the crystallization of metastable anatase in the glass-ceramics as a main phase. The present bulk anatase glass-ceramics will open up an application field for a TiO2-containing photocatalyst.
Spatial nonuniformity of electron energy in a microwave atmospheric-pressure microplasma
Authors: Zhu Li-Guo , Zhang Zhi-Bo , Zhu Xi-Ming , Pu Yi-Kang , Li Ze-Ren
Published: April 2009

The characteristics of the electron energy in a microwave atmospheric-pressure argon microplasma are investigated by a spatially resolved optical emission spectroscopy. By adding tiny amount of xenon (<1 ppm) as tracer gas into the argon discharge, it is found that the spatial distribution of the electrons with energy >8.3 eV is quite different from that of the electrons with energy >11.5 eV. Spatial distribution of the population ratio between 4p and 5p levels of Ar atom is also determined. Furthermore, with a collisional-radiative model, it is found that the spatial variation of this population ratio is mainly attributed to the spatial nonuniformity of the effective electron temperature.
Significant configurational dependence of the electromechanical coupling constant of B0.125Al0.875N
Authors: Tasnádi Ferenc , Abrikosov Igor A. , Katardjiev Ilia
Published: April 2009

Currently, AlN is the preferred material in electroacoustic applications but modern applications necessitate the synthesis of materials with a range of electroacoustic properties. Among the promising candidates are the wurtzite Boron-containing AlN alloys. In here we study theoretically some of the material properties of wurtzite B0.125Al0.875N. The results indicate that wurtzite B0.125Al0.875N exhibits a strong configurational dependence of the electromechanical coupling constant. It is further shown that the lattice parameters as well as the stiffness constants are less sensitive of the atomic configuration and comply well with the Vegard’s rule.
Experimental demonstration of sidewall angle induced bianisotropy in multiple layer negative index metamaterials
Authors: Ku Zahyun , Brueck S. R. J.
Published: April 2009

The effect of a nonzero sidewall angle on the performance of multiple layer fishnet-structure (one to three functional layers) negative index metamaterials is evaluated experimentally. The fabrication-induced sidewall angle results in a bianisotropy (inhomogeneous asymmetry) that is significant at optical frequencies. Good agreement is obtained between the experimental transmission and reflectance measurements and the simulation results. Modifications to the standard parameter retrieval algorithm are discussed.
Positron annihilation in (Ga, Mn)N: A study of vacancy-type defects
Authors: Yang X. L. , Zhu W. X. , Wang C. D. , Fang H. , Yu T. J. , Yang Z. J. , Zhang G. Y. , Qin X. B. , Yu R. S. , Wang B. Y.
Published: April 2009

The vacancy-type defects in (Ga,Mn)N films grown by metal organic chemical vapor deposition were studied by positron annihilation technique. Doppler broadening spectra were measured for the films. Compared to the undoped GaN film, the positron trapping defects in the (Ga,Mn)N films have been changed to a new type defects and its concentration increases with the increasing Mn concentration. By analyzing the S-W correlation plots and our previous results, we identify this type defects in the (Ga,Mn)N as VN-MnGa complex. This type of defects should be considered when understand the magnetic properties in a real (Ga,Mn)N system.
Atomic clock based on transient coherent population trapping
Authors: Guo Tao , Deng Ke , Chen Xuzong , Wang Zhong
Published: April 2009

We proposed a scheme to implement coherent population trapping (CPT) atomic clock based on the transient CPT phenomenon. We proved that the transient transmitted laser power in a typical Λ system near CPT resonance features as a damping oscillation. Also, the oscillating frequency is exactly equal to the frequency detuning from the atomic hyperfine splitting. Therefore, we can directly measure the frequency detuning and then compensated to the output frequency of microwave oscillator to get the standard frequency. By this method, we can further simplify the structure of CPT atomic clock, and make it easier to be digitized and miniaturized.
ZnO glass-ceramics: An alternative way to produce semiconductor materials
Authors: Masai Hirokazu , Toda Tatsuya , Ueno Takahiro , Takahashi Yoshihiro , Fujiwara Takumi
Published: April 2009

Fabrication of transparent glass-ceramics containing ZnO nanocrystallites has been reported. The obtained material shows UV-excited photoluminescence consisting of both broad emission in the visible region and the free exciton emission at 3.28 eV. Since the observed emission depends on the precipitated state of ZnO in the glass matrix, the glass-ceramics obtained by this way will give an alternative selection of semiconductor material with unique optical and electronic functions.
Removal of American mink increases the success of simulated nests in linear habitat
Authors: Padyšáková Eliška , Šálek Martin , Poledník Lukáš , Sedláček František , Albrecht Tomáš
Published: April 2009

Alien species of predators may negatively influence the breeding success of waterfowl. Previous studies have tested whether predator removal causes an increase in nest success and breeding densities; however, conclusions have been contradictory. Here we examine the impact of the removal of introduced American mink, Mustela vison, on the survival of simulated waterfowl nests in two treatment and two control transects, in a linear section of habitat along the Jihlava River, Czech Republic. Nest survival was recorded during two periods (June and July), with minks removed after the first replicate. In total, eight minks were removed from treatment transects. Whereas nest survival in control transects slightly decreased from June to July, the opposite trend, i.e. an increase in nest survival, was apparent in the treatment transects. On the basis of the results, we suggest that a local reduction in mink populations is an effective short-term tool for the conservation of protected waterfowl species. Our study adds to others, reporting potentially adverse effects of alien, introduced, carnivorous species on local biota.
Home-range estimation within complex restricted environments: importance of method selection in detecting seasonal change
Authors: Knight Carolyn M. , Kenward Robert E. , Gozlan Rodolphe E. , Hodder Kathryn H. , Walls Sean S. , Lucas Martyn C.
Published: April 2009

Estimating the home ranges of animals from telemetry data can provide vital information on their spatial behaviour, which can be applied by managers to a wide range of situations including reserve design, habitat management and interactions between native and non-native species. Methods used to estimate home ranges of animals in spatially restricted environments (e.g. rivers) are liable to overestimate areas and underestimate travel distances by including unusable habitat (e.g. river bank). Currently, few studies that collect telemetry data from species in restricted environments maximise the information that can be gathered by using the most appropriate home-range estimation techniques. Simulated location datasets as well as radio-fix data from 23 northern pike (Esox lucius) were used to examine the efficiency of home-range and travel estimators, with and without correction for unusable habitat, for detecting seasonal changes in movements. Cluster analysis most clearly demonstrated changes in range area between seasons for empirical data, also showing changes in patchiness, and was least affected by unusable-environment error. Kernel analysis showed seasonal variation in range area more clearly than peripheral polygons or ellipses. Range span, a linear estimator of home range, had no significant seasonal variation. Results from all range area estimators were smallest in autumn, when cores were least fragmented and interlocation movements smallest. Cluster analysis showed that core ranges were largest and most fragmented in summer, when interlocation distances were most variable, whereas excursion-sensitive methods (e.g. kernels) recorded the largest outlines in spring, when interlocation distances were largest. Our results provide a rationale for a priori selection of home-range estimators in restricted environments. Contours containing 95% of the location density defined by kernel analyses better reflected excursive activity than ellipses or peripheral polygons, whereas cluster analyses better defined range cores in usable habitat and indicate range fragmentation.
Field test of a single-injection gonadotrophin-releasing hormone immunocontraceptive vaccine in female white-tailed deer
Authors: Gionfriddo James P. , Eisemann John D. , Sullivan Kevin J. , Healey Ronald S. , Miller Lowell A. , Fagerstone Kathleen A. , Engeman Richard M. , Yoder Christi A.
Published: April 2009

The development and use of safe, effective and practical wildlife contraceptive agents could reduce reproduction in locally overabundant deer populations in situations where traditional management tools such as regulated hunting cannot be employed. GonaCon Immunocontraceptive Vaccine (the commercial name for a particular gonadotrophin-releasing hormone (GnRH)-based emulsion) was tested in adult female white-tailed deer in a fenced herd near Silver Spring, Maryland, USA. Observations of udder condition were used to identify does that had become pregnant. Necropsy observations, histopathology and serum concentrations of anti-GnRH antibodies, luteinising hormone and progesterone were used to compare health and reproductive status of treated (n = 28) and control (n = 15) deer. After receiving one injection of GonaCon, 88% of treated deer did not become pregnant during the first year and 47% did not become pregnant during the second year after vaccination. No adverse health effects related to vaccination with GonaCon were detected, except for localised injection-site reactions in five (29%) of 17 examined, vaccinated deer. Treatment with GonaCon can be a safe and effective means of inducing temporary infertility in wild white-tailed deer. Ultimately, the management value of GonaCon will be determined by natural-resource professionals who use it as one of many tools to manage deer populations.
Modelling the abundance of wildlife using field surveys and GIS: non-native sambar deer (Cervus unicolor) in the Yarra Ranges, south-eastern Australia
Authors: Forsyth David M. , McLeod Steve R. , Scroggie Michael P. , White Matthew D.
Published: April 2009

Combining abundance data collected in designed field surveys with biophysical data derived from geographic information systems is a powerful way to investigate predictors of spatial variation in the abundance of wildlife. We used such an approach to evaluate hypotheses about factors influencing the abundance of sambar deer (Cervus unicolour Kerr, 1792), a large non-native herbivore, in south-eastern Australia. We developed a spatial model for the abundance of sambar deer faecal pellets in a 3650-ha area in the Upper Yarra Ranges, Victoria. We counted the number of sambar deer faecal pellets along 100 randomly located transects and used a geographic information system to estimate biophysical variables around each transect. We formulated our hypotheses about how those variables might affect the abundance of sambar deer pellets into 22 candidate models and used the deviance information criterion to identify the ‘best’ model(s). Because five models had strong support we used model averaging to generate a predictive model. The three variables included in the predictive model were aspect (abundance of pellets declined with increasing ‘northerliness’ and increased with increasing ‘easterliness’), distance to water and elevation; the latter two variables were positively correlated and had a negative effect on the abundance of pellets. In contrast to previous models of sambar deer abundance in south-eastern Australia, our spatial predictions of the abundance of faecal pellets can be easily tested and updated. Our approach would be useful for modelling the abundances of other wildlife species at a range of spatial scales.
Effect of experimental manipulation on survival and recruitment of feral pigs
Authors: Hanson Laura B. , Mitchell Michael S. , Grand James B. , Jolley D. Buck , Sparklin Bill D. , Ditchkoff Stephen S.
Published: April 2009

Lethal removal is commonly used to reduce the density of invasive-species populations, presuming it reduces population growth rate; the actual effect of lethal removal on the vital rates contributing to population growth, however, is rarely tested. We implemented a manipulative experiment of feral pig (Sus scrofa) populations at Fort Benning, Georgia, USA, to assess the demographic effects of harvest intensity. Using mark–recapture data, we estimated annual survival, recruitment, and population growth rates of populations in a moderately harvested area and a heavily harvested area for 2004–06. Population growth rates did not differ between the populations. The top-ranked model for survival included a harvest intensity effect; model-averaged survival was lower for the heavily harvested population than for the moderately harvested population. Increased immigration and reproduction likely compensated for the increased mortality in the heavily harvested population. We conclude that compensatory responses in feral pig recruitment can limit the success of lethal control efforts.
Feral pigs: predicting future distributions
Authors: Cowled Brendan D. , Giannini Fiona , Beckett Sam D. , Woolnough Andrew , Barry Simon , Randall Lucy , Garner Graeme
Published: April 2009

Feral pig populations are expanding in many regions of the world following historically recent introductions. Populations are controlled to reduce damage to agriculture and the environment, and are also a recreational hunting resource. Knowledge of the area over which feral pigs may expand in the future could be used regionally to assist biosecurity planning, control efforts and the protection of biodiversity assets. The present study sought to estimate the future distribution of a recently introduced, expanding feral pig population in the remote Kimberley region of north-western Australia. An existing survey of feral pig distributions was enhanced and remote-sensing and weather data, reflecting or correlated with factors that may affect feral pig distributions, were collated and analysed. Relationships between feral pig distributions and these data were identified by using a generalised additive modelling approach. By the use of the model, the distribution of favourable habitat was estimated across the study region (89 125 km2). The potential future distribution of feral pigs in the Kimberley was then estimated, assuming only natural dispersal of feral pigs from areas of known feral pig status (cf. hunter-assisted movements or escape of domestic pigs). The modelling suggests that feral pigs could expand their distribution by realistic natural dispersal in the future (to 61 950 km2). This expansion possibility contains several strategically important areas (such as sea ports and biologically significant wetlands). This approach has the potential to improve biosecurity planning for the containment of the feral pig in the Kimberley and may have utility for other recently introduced invasive species in other regions. These results may also be used to improve pest-management programmes and contingency planning for exotic-disease incursions.
The impact of fox control on the relative abundance of forest mammals in East Gippsland, Victoria
Authors: Dexter Nick , Murray Andy
Published: April 2009

Predation by European red foxes is believed to be the major cause of the extinction and decline of a large number of native medium-sized terrestrial mammals in Australia. We examined the impact of poisoning of foxes on the relative abundance of a group of medium-sized mammals in an experiment conducted in three large forest blocks in south-eastern Australia. The blocks consisted of paired sites, as follows: one site where poison baiting was used to control foxes (treatment site) and one where foxes were not controlled (non-treatment site). At all six sites, the population responses of a range of mammals were measured, and compared between treatment and non-treatment sites. The relative fox abundance, as indexed by bait-take, declined during the course of the study at treatment sites and to a lesser extent at non-treatment sites. The decline in bait-take at non-treatment sites was most likely due to treatment sites acting as ecological traps, so that reduced intra-specific competition attracted foxes from non-treatment to treatment sites, where they were subsequently poisoned. There was a significant treatment effect for the abundances of total mammals, long-nosed potoroos, southern brown bandicoots and common brushtail possums, with higher abundances at treatment sites than at non-treatment sites. Common ringtail possums increased in abundance during the course of the study, with no significant difference between treatment and non-treatment sites. There was no significant effect of time or treatment on the abundance of long-nosed bandicoots. The increase in the abundance of native mammals at treatment sites was most likely due to a lower predation pressure by foxes brought about by fox control, and the smaller increase in abundance in non-treatment blocks was likely due to the ecological-trap effect because of fox baiting at treatment sites. The present study demonstrated that broad-scale fox control can lead to increases in the abundance of native mammals in forested habitats, without recourse to aerial baiting or fences. The study also demonstrated that the influence of fox control on the fox abundance can extend well beyond the perimeter of the area baited.
Single molecule mechanics of the kinesin neck
Authors: Bornschlögl Thomas , Woehlke Günther , Rief Matthias
Published: April 2009

Structural integrity as well as mechanical stability of the parts of a molecular motor are crucial for its function. In this study, we used high-resolution force spectroscopy by atomic force microscopy to investigate the force-dependent opening kinetics of the neck coiled coil of Kinesin-1 from
Drosophila melanogaster
. We find that even though the overall thermodynamic stability of the neck is low, the average opening force of the coiled coil is >11 pN when stretched with pulling velocities >150 nm/s. These high unzipping forces ensure structural integrity during motor motion. The high mechanical stability is achieved through a very narrow N-terminal unfolding barrier if compared with a conventional leucine zipper. The experimentally mapped mechanical unzipping profile allows direct assignment of distinct mechanical stabilities to the different coiled-coil subunits. The coiled-coil sequence seems to be tuned in an optimal way to ensure both mechanical stability as well as motor regulation through charged residues.
The augmin complex plays a critical role in spindle microtubule generation for mitotic progression and cytokinesis in human cells
Authors: Uehara Ryota , Nozawa Ryu-suke , Tomioka Akiko , Petry Sabine , Vale Ronald D. , Obuse Chikashi , Goshima Gohta
Published: April 2009

The mitotic spindle is constructed from microtubules (MTs) nucleated from centrosomes, chromosome proximal regions, and preexisting spindle MTs. Augmin, a recently identified protein complex, is a critical factor in spindle MT-based MT generation in
Drosophila
S2 cells. Previously, we identified one subunit of human augmin. Here, by using mass spectrometry, we identified the full human augmin complex of 8 subunits and show that it interacts with the γ-tubulin ring complex (γ-TuRC). Unlike augmin-depleted S2 cells, in which the defect in spindle-mediated MT generation is mostly compensated by centrosomal MTs, augmin knockdown alone in HeLa cells triggers the spindle checkpoint, reduces tension on sister kinetochores, and severely impairs metaphase progression. Human augmin knockdown also reduces the number of central spindle MTs during anaphase and causes late-stage cytokinesis failure. A link between augmin and γ-TuRC is likely critical for these functions, because a γ-TuRC mutant that attenuates interaction with augmin does not restore function in vivo. These results demonstrate that MT generation mediated by augmin and γ-TuRC is critical for chromosome segregation and cytokinesis in human cells.
Activated cAMP receptors switch encystation into sporulation
Authors: Kawabe Yoshinori , Morio Takahiro , James John L. , Prescott Alan R. , Tanaka Yoshimasa , Schaap Pauline
Published: April 2009

Metazoan embryogenesis is controlled by a limited number of signaling modules that are used repetitively at successive developmental stages. The development of social amoebas shows similar reiterated use of cAMP-mediated signaling. In the model
Dictyostelium discoideum
, secreted cAMP acting on 4 cAMP receptors (cARs1-4) coordinates cell movement during aggregation and fruiting body formation, and induces the expression of aggregation and sporulation genes at consecutive developmental stages. To identify hierarchy in the multiple roles of cAMP, we investigated
cAR
heterogeneity and function across the social amoeba phylogeny. The gene duplications that yielded
cARs 2-4
occurred late in evolution. Many species have only a
cAR1
ortholog that duplicated independently in the Polysphondylids and Acytostelids. Disruption of both cAR genes of
Polysphondylium pallidum
(
Ppal
) did not affect aggregation, but caused complete collapse of fruiting body morphogenesis. The stunted structures contained disorganized stalk cells, which supported a mass of cysts instead of spores; cAMP triggered spore gene expression in
Ppal
, but not in the
cAR
null mutant, explaining its sporulation defect. Encystation is the survival strategy of solitary amoebas, and lower taxa, like
Ppal
, can still encyst as single cells. Recent findings showed that intracellular cAMP accumulation suffices to trigger encystation, whereas it is a complementary requirement for sporulation. Combined, the data suggest that cAMP signaling in social amoebas evolved from cAMP-mediated encystation in solitary amoebas; cAMP secretion in aggregates prompted the starving cells to form spores and not cysts, and additionally organized fruiting body morphogenesis. cAMP-mediated aggregation was the most recent innovation.
Integrated cross-domain object storage in working memory: Evidence from a verbal–spatial memory task
Authors: Morey Candice C.
Published: April 2009

Working-memory theories often include domain-specific verbal and visual stores (e.g., the phonological and visuospatial buffers of Baddeley, 1986), and some also posit more general stores thought to be capable of holding verbal or visuospatial materials (Baddeley, 2000; Cowan, 2005). However, it is currently unclear which type of store is primarily responsible for maintaining objects that include components from multiple domains. In these studies, a spatial array of letters was followed by a single probe identical to an item in the array or differing systematically in spatial location, letter identity, or their combination. Concurrent verbal rehearsal suppression impaired memory in each of these trial types in a task that required participants to remember verbal–spatial binding, but did not impair memory for spatial locations if the task did not require verbal–spatial binding for a correct response. Thus, spatial information might be stored differently when it must be bound to verbal information. This suggests that a cross-domain store such as the episodic buffer of Baddeley (2000) or the focus of attention of Cowan (2001) might be used for integrated object storage, rather than the maintenance of associations between features stored in separate domain-specific buffers.
Good vibrations: Human interval timing in the vibrotactile modality
Authors: Jones Luke A. , Poliakoff Ellen , Wells Jill
Published: April 2009

This article reports a detailed examination of timing in the vibrotactile modality and comparison with that of visual and auditory modalities. Three experiments investigated human timing in the vibrotactile modality. In Experiment 1, a staircase threshold procedure with a standard duration of 1,000 ms revealed a difference threshold of 160.35 ms for vibrotactile stimuli, which was significantly higher than that for auditory stimuli (103.25 ms) but not significantly lower than that obtained for visual stimuli (196.76 ms). In Experiment 2, verbal estimation revealed a significant slope difference between vibrotactile and auditory timing, but not between vibrotactile and visual timing. That is, both vibrations and lights were judged as shorter than sounds, and this comparative difference was greater at longer durations than at shorter ones. In Experiment 3, performance on a temporal generalization task showed characteristics consistent with the predications of scalar expectancy theory (SET: Gibbon, 1977) with both mean accuracy and scalar variance exhibited. The results were modelled using the modified Church and Gibbon model (MCG; derived by Wearden, 1992, from Church & Gibbon 1982). The model was found to give an excellent fit to the data, and the parameter values obtained were compared with those for visual and auditory temporal generalization. The pattern of results suggest that timing in the vibrotactile modality conforms to SET and that the internal clock speed for vibrotactile stimuli is significantly slower than that for auditory stimuli, which is logically consistent with the significant differences in difference threshold that were obtained.
LABORATORY MEASUREMENTS OF NiH BY FOURIER TRANSFORM DISPERSED FLUORESCENCE
Authors: Vallon Raphaël , Richard Cyril , Crozet Patrick , Wannous Ghassan , Ross Amanda
Published: April 2009

Red and orange bands of laser-induced fluorescence in NiH have been recorded on a Fourier transform interferometer at Doppler resolution. The spectra show strong transitions to low-lying vibronic states which are not thermally populated in a laboratory source, and therefore do not appear in laser excitation spectra, but which would be expected to contribute significantly to any stellar spectrum. The strongest bands belong to the G[Ω′ 5/2]–X
2 2Δ3/2, I[Ω′ 3/2]–X
2, and 2Δ3/2
I[Ω′ 3/2]–W
1
2Π3/2 systems. Measurements are reported for 58NiH, 60NiH, and 62NiH.
XMAP215–EB1 Interaction Is Required for Proper Spindle Assembly and Chromosome Segregation in Xenopus Egg Extract
Authors: Kronja Iva , Kruljac-Letunic Anamarija , Caudron-Herger Maïwen , Bieling Peter , Karsenti Eric
Published: April 2009

In metaphase Xenopus egg extracts, global microtubule growth is mainly promoted by two unrelated microtubule stabilizers, end-binding protein 1 (EB1) and XMAP215. Here, we explore their role and potential redundancy in the regulation of spindle assembly and function. We find that at physiological expression levels, both proteins are required for proper spindle architecture: Spindles assembled in the absence of EB1 or at decreased XMAP215 levels are short and frequently multipolar. Moreover, the reduced density of microtubules at the equator of ΔEB1 or ΔXMAP215 spindles leads to faulty kinetochore–microtubule attachments. These spindles also display diminished poleward flux rates and, upon anaphase induction, they neither segregate chromosomes nor reorganize into interphasic microtubule arrays. However, EB1 and XMAP215 nonredundantly regulate spindle assembly because an excess of XMAP215 can compensate for the absence of EB1, whereas the overexpression of EB1 cannot substitute for reduced XMAP215 levels. Our data indicate that EB1 could positively regulate XMAP215 by promoting its binding to the microtubules. Finally, we show that disruption of the mitosis-specific XMAP215–EB1 interaction produces a phenotype similar to that of either EB1 or XMAP215 depletion. Therefore, the XMAP215–EB1 interaction is required for proper spindle organization and chromosome segregation in Xenopus egg extracts.
Uncoupling Stress Granule Assembly and Translation Initiation Inhibition
Authors: Mokas Sophie , Mills John R. , Garreau Cristina , Fournier Marie-Josée , Robert Francis , Arya Prabhat , Kaufman Randal J. , Pelletier Jerry , Mazroui Rachid
Published: April 2009

Cytoplasmic stress granules (SGs) are specialized regulatory sites of mRNA translation that form under different stress conditions known to inhibit translation initiation. The formation of SG occurs via two pathways; the eukaryotic initiation factor (eIF) 2α phosphorylation-dependent pathway mediated by stress and the eIF2α phosphorylation-independent pathway mediated by inactivation of the translation initiation factors eIF4A and eIF4G. In this study, we investigated the effects of targeting different translation initiation factors and steps in SG formation in HeLa cells. By depleting eIF2α, we demonstrate that reduced levels of the eIF2.GTP.Met-tRNAiMet ternary translation initiation complexes is sufficient to induce SGs. Likewise, reduced levels of eIF4B, eIF4H, or polyA-binding protein, also trigger SG formation. In contrast, depletion of the cap-binding protein eIF4E or preventing its assembly into eIF4F results in modest SG formation. Intriguingly, interfering with the last step of translation initiation by blocking the recruitment of 60S ribosome either with 2-(4-methyl-2,6-dinitroanilino)-N-methylpropionamideis or through depletion of the large ribosomal subunits protein L28 does not induce SG assembly. Our study identifies translation initiation steps and factors involved in SG formation as well as those that can be targeted without induction of SGs.
Eps15 Homology Domain 1-associated Tubules Contain Phosphatidylinositol-4-Phosphate and Phosphatidylinositol-(4,5)-Bisphosphate and Are Required for Efficient Recycling
Authors: Jović Marko , Kieken Fabien , Naslavsky Naava , Sorgen Paul L. , Caplan Steve
Published: April 2009

The C-terminal Eps15 homology domain (EHD) 1/receptor-mediated endocytosis-1 protein regulates recycling of proteins and lipids from the recycling compartment to the plasma membrane. Recent studies have provided insight into the mode by which EHD1-associated tubular membranes are generated and the mechanisms by which EHD1 functions. Despite these advances, the physiological function of these striking EHD1-associated tubular membranes remains unknown. Nuclear magnetic resonance spectroscopy demonstrated that the Eps15 homology (EH) domain of EHD1 binds to phosphoinositides, including phosphatidylinositol-4-phosphate. Herein, we identify phosphatidylinositol-4-phosphate as an essential component of EHD1-associated tubules in vivo. Indeed, an EHD1 EH domain mutant (K483E) that associates exclusively with punctate membranes displayed decreased binding to phosphatidylinositol-4-phosphate and other phosphoinositides. Moreover, we provide evidence that although the tubular membranes to which EHD1 associates may be stabilized and/or enhanced by EHD1 expression, these membranes are, at least in part, pre-existing structures. Finally, to underscore the function of EHD1-containing tubules in vivo, we used a small interfering RNA (siRNA)/rescue assay. On transfection, wild-type, tubule-associated, siRNA-resistant EHD1 rescued transferrin and β1 integrin recycling defects observed in EHD1-depleted cells, whereas expression of the EHD1 K483E mutant did not. We propose that phosphatidylinositol-4-phosphate is an essential component of EHD1-associated tubules that also contain phosphatidylinositol-(4,5)-bisphosphate and that these structures are required for efficient recycling to the plasma membrane.
Selecting and Sorting Waxy Wheat Kernels Using Near‐Infrared Spectroscopy
Authors: Dowell F. E. , Maghirang E. B. , Graybosch R. A. , Berzonsky W. A. , Delwiche S. R.
Published: April 2009

An automated single kernel near‐infrared (NIR) sorting system was used to separate single wheat (Triticum aestivum L.) kernels with amylose‐free (waxy) starch from reduced‐amylose (partial waxy) or wild‐type wheat kernels. Waxy kernels of hexaploid wheat are null for the granule‐bound starch synthase alleles at all three Wx gene loci; partial waxy kernels have at least one null and one functional allele. Wild‐type kernels have three functional alleles. Our results demonstrate that automated single kernel NIR technology can be used to select waxy kernels from segregating breeding lines or to purify advanced breeding lines for the low‐amylose kernel trait. Calibrations based on either amylose content or the waxy trait performed similarly. Also, a calibration developed using the amylose content of waxy, partial waxy, and wild‐type durum (T. turgidum L. var durum) wheat enabled adequate sorting for hard red winter and hard red spring wheat with no modifications. Regression coefficients indicated that absorption by starch in the NIR region contributed to the classification models. Single kernel NIR technology offers significant benefits to breeding programs that are developing wheat with amylose‐free starches.