bluuebunny/crossref_metadata_2025 huggingface dataset:
Bayesian analysis of input uncertainty in hydrological modeling: 2. Application
Authors: Kavetski Dmitri , Kuczera George , Franks Stewart W.
Published: March 2006

The Bayesian total error analysis (BATEA) methodology directly addresses both input and output errors in hydrological modeling, requiring the modeler to make explicit, rather than implicit, assumptions about the likely extent of data uncertainty. This study considers a BATEA assessment of two North American catchments: (1) French Broad River and (2) Potomac basins. It assesses the performance of the conceptual Variable Infiltration Capacity (VIC) model with and without accounting for input (precipitation) uncertainty. The results show the considerable effects of precipitation errors on the predicted hydrographs (especially the prediction limits) and on the calibrated parameters. In addition, the performance of BATEA in the presence of severe model errors is analyzed. While BATEA allows a very direct treatment of input uncertainty and yields some limited insight into model errors, it requires the specification of valid error models, which are currently poorly understood and require further work. Moreover, it leads to computationally challenging highly dimensional problems. For some types of models, including the VIC implemented using robust numerical methods, the computational cost of BATEA can be reduced using Newton‐type methods.
Effect of soil roughness on the inversion of off‐ground monostatic GPR signal for noninvasive quantification of soil properties
Authors: Lambot Sébastien , Antoine Michaël , Vanclooster Marnik , Slob Evert C.
Published: March 2006

We report on a laboratory experiment that investigates the effect of soil surface roughness on the identification of the soil electromagnetic properties from full‐wave inversion of ground‐penetrating radar (GPR) data in the frequency domain. The GPR system consists of an ultrawide band stepped‐frequency continuous‐wave radar combined with an off‐ground monostatic horn antenna. Radar measurements were performed above a rectangular container filled with a loose sandy soil subject to seven water contents and four random surface roughnesses, including a smooth surface as reference. Compared to previous studies, we have reduced the modeling error of the GPR signal for the smooth surface case thanks to improved antenna transfer functions by solving an overdetermined system of equations based on six model configurations instead of only three. Then, the continuously increasing effect of surface roughness on the radar signal with respect to frequency is clearly observed. In close accordance with Rayleigh's criterion, both the radar signal and the inversely estimated parameters are not significantly affected if the surface protuberances are smaller than one eighth of a wavelength. In addition, when this criterion is not respected, errors are made in the estimated parameters, but the inverse solution remains stable. This demonstrates the promising perspectives for application of GPR for noninvasive water content estimation in agricultural and environmental field applications.
An evaluation of the influence of aquifer heterogeneity on permeable reactive barrier design
Authors: Hemsi Paulo S. , Shackelford Charles D.
Published: March 2006

The influence of heterogeneity in aquifer hydraulic conductivity (K) on contaminant plume patterns and the required thickness and length of permeable reactive barriers (PRBs) used for in situ remediation is evaluated using stochastic modeling. The results provide a quantitative means for evaluating the effects of (1) the level of aquifer heterogeneity as reflected by the standard deviation of the logarithm of K, σlnK, (2) the aquifer correlation structure anisotropy represented by the ratio of correlation lengths, λx/λy, and (3) DPRB representing the distance from the contaminant source zone to the PRB. In terms of PRB thickness, a probabilistic factor of safety related to uncertainty in influent groundwater seepage velocities (FS1,90) at the location of the PRB is quantified. In terms of PRB length, a probabilistic factor of safety related to uncertainty in the length of a PRB required to capture the contaminant plume, defined as the capture length ratio (CLR), is quantified. The mean and standard deviation of FS1,90 significantly increase as σlnK increases from 0.2 to 1.6, and slightly increase as λx/λy increases from 1.0 to 3.0 and DPRB increases from 15 to 45 m. The values for the factor of safety for PRB thickness versus σlnK compare favorably with previously published values based on a different methodology. The mean and standard deviation of CLR increase with increasing σlnK and with increasing DPRB, and decrease slightly with increasing λx/λy. Finally, the ranges in CLR are correlated with strongly divergent and strongly convergent plume patterns.
Improvement of the Kei2 source for a new carbon therapy facility
Authors: Muramatsu M. , Kitagawa A. , Ogawa Hirotsugu , Iwata Y. , Yamamoto K. , Yamada S. , Ogawa Hiroyuki , Fujimoto T. , Yoshida Y. , Drentje A. G.
Published: March 2006

A compact electron cyclotron resonance ion source with all permanent magnets has been developed for a new carbon therapy facility at NIRS. Initial tests with the Kei2 source have given a maximum intensity of 530eμA for C4+ at an extraction voltage of 40 kV and beam stability of better than 6% for 90 h at 280eμA at 30 kV. In these beam tests, there was continuously unwanted discharge around the puller at high-voltage extraction (above 40 kV). The start of discharge is caused by the short distance of 5 mm between the end of the plasma chamber and puller. At high-voltage extraction, this discharge will give rise to unwanted vapor from the copper puller. Then, the vacuum pressure in the extraction region will become worse. In order to suppress the discharge, the plasma chamber and puller were modified. Finally, a beam intensity of 380eμA was obtained with good stability at an extraction voltage of 30 kV. This article describes the modification of the puller for stable beam extraction, measurements of beam emittance, and improvement of C4+ intensity.
Large Raman-scattering activities for the low-frequency modes of substituted benzenes: Induced polarizability and stereo-specific ring-substituent interactions
Authors: Yamakita Yoshihiro , Isogai Yumiko , Ohno Koichi
Published: March 2006

The large nonresonant Raman-scattering activities of the out-of-plane bending and torsional modes of monosubstituted benzene analogs are studied by low-frequency Raman experiments and B3LYP∕6-31++G(d,p) calculations. Electronic interactions between the σ orbitals of the substituent and the π orbitals of the ring are found to enhance the Raman activities, depending on the substituent and its conformation. In the case of tert-butylbenzene [C6H5C(CH3)3] and trimethylphenylsilane [C6H5Si(CH3)3], three single bonds which are linked to the α atom of the substituent have low rotational barriers around the joint bond. Nearly free rotation of the substituents leads to a significant probability for one of the single bonds to occupy a conformation close to the vertical configuration with respect to the ring at room temperature. The resultant σ-π electronic interaction gives rise to the large Raman activities. In contrast, those possessing a single bond in a coplanar (or nearly coplanar) configuration at the most stable equilibrium state, i.e., anisole (C6H5OCH3), thioanisole (C6H5SCH3), and N-methylaniline (C6H5NHCH3), display no prominent Raman bands for the low-frequency vibrational modes. In these molecules, the σ-π conjugation does not take place due to the orthogonal orientation of the orbitals. Strong conformational dependence of the σ-π Raman enhancement is clearly obtained for the metastable vertical conformer of thioanisole, for which Raman activities are one-order magnitude greater than those of the coplanar conformer.
Structural transitions in the 309-atom magic number Lennard-Jones cluster
Authors: Noya Eva G. , Doye Jonathan P. K.
Published: March 2006

The thermal behavior of the 309-atom Lennard-Jones cluster, whose structure is a complete Mackay icosahedron, has been studied by parallel tempering Monte Carlo simulations. Surprisingly for a magic number cluster, the heat capacity shows a very pronounced peak before melting, which is attributed to several coincident structural transformation processes. The main transformation is somewhat akin to surface roughening and involves a cooperative condensation of vacancies and adatoms that leads to the formation of pits and islands one or two layers thick on the Mackay icosahedron. The second transition in order of importance involves a whole scale transformation of the cluster structure and leads to a diverse set of twinned structures that are assemblies of face-centered-cubic tetrahedra with six atoms along their edges, i.e., one atom more than the edges of the 20 tetrahedra that make up the 309-atom Mackay icosahedron. A surface reconstruction of the icosahedron from a Mackay to an anti-Mackay overlayer is also observed, but with a lower probability.
Structural transition of actin filament in a cell-sized water droplet with a phospholipid membrane
Authors: Hase M. , Yoshikawa K.
Published: March 2006

Actin filament, F-actin, is a semiflexible polymer with a negative charge, and is one of the main constituents of cell membranes. To clarify the effect of cross talk between a phospholipid membrane and actin filaments in cells, we conducted microscopic observations on the structural changes in actin filaments in a cell-sized (several tens of micrometers in diameter) water droplet coated with a phospholipid membrane such as phosphatidylserine (PS; negatively charged head group) or phosphatidylethanolamine (PE; neutral head group) as a simple model of a living cell membrane. With PS, actin filaments are distributed uniformly in the water phase without adsorption onto the membrane surface between 2 and 6mM Mg2+, while between 6 and 12mM Mg2+, actin filaments are adsorbed onto the inner membrane surface. With PE, the actin filaments are uniformly adsorbed onto the inner membrane surface between 2 and 12mM Mg2+. With both PS and PE membranes, at Mg2+ concentrations higher than 12mM, thick bundles are formed in the bulk water droplet accompanied by the dissolution of actin filaments from the membrane surface. The attraction between actin filaments and membrane is attributable to an increase in the translational entropy of counterions accompanied by the adsorption of actin filaments onto the membrane surface. These results suggest that a microscopic water droplet coated with phospholipid can serve as an easy-to-handle model of cell membranes.
Casimir effect in a two-dimensional signature changing space-time
Authors: Darabi F. , Setare M. R.
Published: March 2006

We study the Casimir effect for free massless scalar fields propagating on a two-dimensional cylinder with a metric that admits a change of signature from Lorentzian to Euclidean. We obtain a nonzero pressure, on the hypersurfaces of signature change, which destabilizes the signature changing region and so alters the energy spectrum of scalar fields. The modified region and spectrum, themselves, back react on the pressure. Moreover, the central term of diffeomorphism algebra of corresponding infinite conserved charges changes correspondingly.
Enhancement of the light output of GaN-based ultraviolet light-emitting diodes by a one-dimensional nanopatterning process
Authors: Hong Hyun-Gi , Kim Seok-Soon , Kim Dong-Yu , Lee Takhee , Song June-O. , Cho J. H. , Sone C. , Park Y. , Seong Tae-Yeon
Published: March 2006

We have demonstrated the enhancement of the output power of ultraviolet GaN-based light-emitting diodes (LEDs) by using one-dimensionally nanopatterned Cu-doped indium oxide(CIO)/indium tin oxide (ITO) p-type contact layers. The one-dimensional (1D) nanopatterns (250nm in width and 100nm in depth) are defined using a TiO2 1D nanomask fabricated by means of a surface relief grating technique. When fabricated with the nanopatterned p-contact layers, the output power of LEDs is improved by 40 and 63% at 20mA as compared to those fabricated with the unpatterned CIO/ITO and conventional Ni∕Au contacts, respectively.
Fabrication and characterization of solid-state nanopores using a field emission scanning electron microscope
Authors: Chang Hung , Iqbal Samir M. , Stach Eric A. , King Alexander H. , Zaluzec Nestor J. , Bashir Rashid
Published: March 2006

The fabrication of solid-state nanopores using the electron beam of a transmission electron microscope (TEM) has been reported in the past. Here, we report a similar method to fabricate solid-state nanopores using the electron source of a conventional field-emission scanning electron microscope (FESEM) instead. Micromachining was used to create initial pore diameters between 50nm and 200nm, and controlled pore shrinking to sub 10nm diameters was performed subsequently during in situ processing in the FESEM. Noticeably, different shrinking behavior was observed when using irradiation from the electron source of the FESEM than the TEM. Unlike previous reports of TEM mediated pore shrinkage, the mechanism of pore shrinkage when using the FESEM could be a result of surface defects generated by radiolysis and subsequent motion of silicon atoms to the pore periphery.
Effect of oxide overlayer formation on the growth of gold catalyzed epitaxial silicon nanowires
Authors: Jagannathan Hemanth , Nishi Yoshio , Reuter Mark , Copel Matthew , Tutuc Emanuel , Guha Supratik , Pezzi Rafael P.
Published: March 2006

A direct dependence between the inadvertent formation of SiO2 on gold films deposited on silicon ⟨111⟩ substrates, and the nucleation and yield of epitaxial, gold catalyzed, silicon nanowires grown on such substrates is reported. The unintended SiO2 layer formed due to the diffusion of silicon from the underlying substrate through the gold film is observed to be 0.5nm with medium energy ion scattering after brief exposures of 10–15min in air. Silicon nanowires grown at 500°C on such samples show reduced nucleation and growth. A remarkable improvement in nanowire nucleation density and epitaxy is observed on removing the SiO2 overlayer prior nanowire growth.
Straining of monocrystalline silicon thin films with the use of porous silicon as stress generating nanomaterial
Authors: Marty O. , Nychyporuk T. , de la Torre J. , Lysenko V. , Bremond G. , Barbier D.
Published: March 2006

A simple and low cost technological approach for the straining of thin crystalline silicon (Si) films using porous silicon (PS) as stress generating nanomaterial is reported. Structural analysis of the PS∕Si structures is performed by transmission electron microscopy. Raman scattering spectroscopy is used for the evaluation of stress and strain values in the strained thin Si films. Depending on the thickness of the strained Si films, the maximum strain values are found to be in a range from 1% to 1.4%. Various modifications of electronic properties of the strained Si films are observed by photoluminescence spectroscopy. For example, strain induced redshift of the Si energy band gap and splitting of the valence band are detected.
Liquid-crystal-based terahertz tunable Lyot filter
Authors: Chen Chao-Yuan , Pan Ci-Ling , Hsieh Cho-Fan , Lin Yea-Feng , Pan Ru-Pin
Published: March 2006

A two-element tunable Lyot filter operating in the terahertz (THz) frequency range is demonstrated. The central bandpass frequency of the filter can be continuously tuned from 0.388to0.564THz (a fractional tuning range of 40%) using magnetically controlled birefringence in nematic liquid crystals. The transmission bandwidth is 0.1THz and the insertion loss of the present device is 8dB due to the scattering of LC molecules in the thick LC cells. This filter can be operated at room temperature.
Nonlinear dynamics accompanying polarization switching in vertical-cavity surface-emitting lasers with orthogonal optical injection
Authors: Gatare I. , Sciamanna M. , Buesa J. , Thienpont H. , Panajotov K.
Published: March 2006

We present an experimental investigation of a vertical-cavity surface-emitting laser (VCSEL) submitted to orthogonal optical injection, i.e., the injected light is linearly polarized and orthogonal to that emitted by the solitary VCSEL. Bifurcation boundaries of qualitatively different dynamics are mapped out in the frequency detuning-injection strength plane. We unveil rich and complex dynamics including injection locking, limit cycle, wave mixing, and period doubling route to chaos.
Final thermally stimulated discharge current in nonpolar materials
Authors: Neagu Eugen R. , Vassilikou-Dova Aglaia
Published: March 2006

The final thermally stimulated discharge current technique is used to study the molecular movements in nonpolar dielectrics. The main peak is an apparent peak being very sensitive to the experimental conditions. The experimental conditions can be chosen so that the thermal activation energy W, a characteristic parameter which has to be independent of the experimental conditions, can be determined. Five relaxations have been identified for Teflon FEP (a copolymer of tetrafluoroethylene with hexafluoropropylene) in the temperature range from 30to320K. W is in the range from 0.06to0.53eV.
Thermal stability of a HfO2∕SiO2 interface
Authors: Ikarashi Nobuyuki , Watanabe Koji , Masuzaki Koji , Nakagawa Takashi
Published: March 2006

Using high-angle annular-dark-field scanning transmission electron microscopy, we showed how annealing at 1000°C changes the chemical composition distribution at a HfO2∕SiO2 interface. The observed change in the distribution was analyzed in terms of Hf diffusion in SiO2; the diffusion coefficient was estimated to be 2.5×10−18cm2∕s. This diffusion coefficient indicates that the high-temperature annealing, such as that in the conventional dopant activation process used to fabricate semiconductor devices, barely changes the chemical composition distribution at the HfO2∕SiO2 interface.
Field-effect transistors with thin films of perylene on SiO2 and polyimide gate insulators
Authors: Ohta Toshio , Nagano Takayuki , Ochi Kenji , Kubozono Yoshihiro , Fujiwara Akihiko
Published: March 2006

Field-effect transistor (FET) devices have been fabricated with thin films of perylene on SiO2 and polyimide gate insulators, and p-channel FET properties have been found in both FET devices. The perylene FET devices with SiO2 and polyimide gate insulators exhibited field-effect mobility, μ, values of 7.0×10−3 and 3.7×10−4cm2V−1s−1, respectively, at 300K under vacuum of 10−6Torr. These FET devices were found to operate under atmospheric condition after exposure to air. The μ value increased with increasing temperature from 160to280K, showing a hopping carrier transport.
Influence of bicrystal microstructural defects on high-transition-temperature direct-current superconducting quantum interference device
Authors: Wu C. H. , Sou U. C. , Chen J. C. , Chen K. L. , Yang H. C. , Hsu M. H. , Lai T. S. , Jeng J. T. , Tsai Y. S. , Horng H. E.
Published: March 2006

Using atomic force microscopy and scanning electron microscopy (SEM), we investigate the correlations between the microstructural defects and the electrical characteristics of the bicrystal grain-boundary Josephson junctions and dc superconducting quantum inference devices (SQUIDs). The structural defects are shown to correlate qualitatively with the characteristics of grain-boundary Josephson junctions patterned on the YBa2Cu3O7−x film. SEM images show that these defects grown on the grain boundary were a few submicron depth of the groove. The low flux noise characteristics were observed when the groove depth was smaller than 18nm in the junctions of the SQUID. The existence of these defects is expected to affect the supercurrent and the motion of the magnetic flux in the films, which dominate the excess noise in the SQUID with bicrystal junctions.
Study of porous glass doped with quantum dots or laser dyes under alpha irradiation
Authors: Létant S. E. , Wang T.-F.
Published: March 2006

We demonstrate that nanocomposite materials based on semiconductor quantum dots have potential for radiation detection via scintillation. While quantum dots and laser dyes both emit in the visible range at room temperature, the Stokes shift of the dyes is significantly larger. The scintillation output of both systems was studied under alpha irradiation and interpreted using a combination of energy loss and photon transport Monte Carlo simulation models. The comparison of the two systems, which allows the quantification of the role played by the Stokes shift in the scintillation output, opens up exciting possibilities for a new class of scintillators that would take advantage of the limitless assembly of nanocrystals in large, transparent, and sturdy matrices.
Current filamentation in discharge-excited F2-based excimer laser gas mixtures
Authors: Mathew D. , Bastiaens H. M. J. , Boller K.-J. , Peters P. J. M.
Published: March 2006

Discharge instabilities in x-ray preionized F2-doped excimer laser gas mixtures are investigated using an intensified charge coupled device camera with a gating time of 300ps. In contradiction with earlier theories and observations, it is found that the discharges in He∕F2 mixtures are homogeneous only at very low concentration of F2 (0.025%). We present experimental results, which prove that in He∕Kr∕F2 mixtures the appearance of discharge filaments is coupled with the presence of F2 rather than Kr.
Optical properties of nanocrystalline diamond thin films
Authors: Achatz P. , Garrido J. A. , Stutzmann M. , Williams O. A. , Gruen D. M. , Kromka A. , Steinmüller D.
Published: March 2006

The optical properties of nanocrystalline diamond films grown from a hydrogen-rich CH4∕H2 gas phase by hot filament chemical vapor deposition, as well as from an argon-rich Ar∕CH4 gas phase by microwave plasma enhanced chemical vapor deposition, are reported. The influence of nitrogen incorporation on the optical absorption is investigated. The diamond films are characterized by photothermal deflection spectroscopy and temperature dependent spectrally resolved photoconductivity. An onset of absorption at about 0.8eV in undoped films is attributed to transitions from π to π states introduced into the band gap by the high amount of sp2 bonded carbon at the grain boundaries. Incorporation of nitrogen leads to a strong absorption in the whole energy spectrum, as a result of the increasing number of sp2 carbon atoms. The effect of surface states has been observed in the high energy region of the spectrum. Transitions to the conduction band tail and photothermal ionization processes account for the observed onset at 4.4eV. Photocurrent quenching at about 3.3eV is observed in the case of samples grown from a hydrogen-rich CH4∕H2 gas phase.
Reactive metal contact at indium–tin–oxide/self-assembled monolayer interfaces
Authors: Cho Jeong Ho , Park Yeong Don , Kim Do Hwan , Kim Woong-Kwon , Jang Ho Won , Lee Jong-Lam , Cho Kilwon
Published: March 2006

With the aim of improving the electrical and adhesion properties of the indium–tin–oxide (ITO) electrode/organic interface, we tested Cl- and CF3-terminated self-assembled monolayers (SAMs), which react with the indium atoms of the electrode, and compared the results to those obtained using a CH3-terminated SAM. The contact resistance of the interface between the Cl-terminated surface and the ITO electrode (1.5kΩ) was found to be much lower than that of the interface between the ITO and the CF3-terminated surface (21.3kΩ), which can be attributed to the higher dipole moment of the In–Cl complex compared to the In–F complex. In the ITO films deposited on the CH3-terminated surface, the contact resistance (138.0kΩ) was much higher than those of the reactive metal contacts because the ITO thin film deposited on the CH3-terminated surface does not react with the SAM.
Light emission from Si nanoclusters formed at low temperatures
Authors: Pi X. D. , Zalloum O. H. Y. , Roschuk T. , Wojcik J. , Knights A. P. , Mascher P. , Simpson P. J.
Published: March 2006

Photoluminescence (PL) from amorphous Si nanoclusters (Si-ncls) formed by thin-film deposition via electron-cyclotron resonance plasma-enhanced chemical vapor deposition followed by annealing at temperatures ⩽875°C has been investigated. We find that Si-ncls grow very slowly after their initial nucleation at low temperatures. An increase in the size of Si-ncls, which can be controlled by the annealing temperature, induces a redshift in the Si-ncl PL peak. While the emitted optical power is more than 100 times smaller than that of Si nanocrystals formed in an identically deposited film, it is increased by a factor of up to approximately four times following hydrogen passivation. The incorporation of hydrogen causes a redshift in the PL peak position, suggesting a partial hydrogenation induced bond distortion of the Si-ncls. This redshift decreases with increasing hydrogen ambient annealing temperature.
Microcompression of nanocrystalline nickel
Authors: Schuster B. E. , Wei Q. , Zhang H. , Ramesh K. T.
Published: March 2006

Microcompression is a technique that was developed as a means to probe the properties of micrometer-sized specimens using a modification of a conventional nanoindentation system. We use this technique to present the first uniaxial compressive data on electrodeposited nanocrystalline nickel (a material system where the grain size is much smaller than the specimen size). The compression-tension asymmetry of this nanocrystalline material is also discussed.
Carrier loss channels for non-collected carrier in InAsxP1−x∕InP multiquantum well solar cells
Authors: Khan Aurangzeb , Freundlich A.
Published: March 2006

We present here the direct observation of majority carrier (electron) defects generation from chemical-beam epitaxy grown InAsxP1−x∕InP multiquantum-well solar cell structures by deep level transient spectroscopy. Four dominant majority carrier levels E1, E2, E3, and E4 at energy position EC−0.17eV, EC−0.25eV, EC−0.57eV, and EC−0.75eV below the conduction-band edge have been observed. Detailed analysis of double-correlation deep level transient spectroscopy (DDLTS) measurements shows that traps E1, E2, E2, and E4 are located at the well-barrier interfacial zone or/and extended over the whole region occupied by the quantum wells. The midgap center E3 has large capture cross sections and is found to exhibit significant dependence of the thermal emission rates on electric field, from DDLTS measurements. These characteristics indicate that the electron trap E3 at EC−0.57eV acts as a strong recombination center and could be responsible for the main carrier loss channel for non-collected carrier in the device.
Spatio-temporal analysis of wildfire ignitions in the St Johns River Water Management District, Florida
Authors: Genton Marc G. , Butry David T. , Gumpertz Marcia L. , Prestemon Jeffrey P.
Published: March 2006

We analyse the spatio-temporal structure of wildfire ignitions in the St Johns River Water Management District in north-eastern Florida. We show, using tools to analyse point patterns (e.g. the L-function), that wildfire events occur in clusters. Clustering of these events correlates with irregular distribution of fire ignitions, including lightning and human sources, and fuels on the landscape. In addition, we define a relative clustering index that summarizes the amount of clustering over various spatial scales. We carry our analysis in three steps: purely temporal, purely spatial, and spatio-temporal. Our results show that arson and lightning are the leading causes of wildfires in this region and that ignitions by railroad, lightning, and arson are spatially more clustered than ignitions by other accidental causes.
Predicting the ignition of crown fuels above a spreading surface fire. Part I: model idealization
Authors: Cruz Miguel G. , Butler Bret W. , Alexander Martin E. , Forthofer Jason M. , Wakimoto Ronald H.
Published: March 2006

A model was developed to predict the ignition of forest crown fuels above a surface fire based on heat transfer theory. The crown fuel ignition model (hereafter referred to as CFIM) is based on first principles, integrating: (i) the characteristics of the energy source as defined by surface fire flame front properties; (ii) buoyant plume dynamics; (iii) heat sink as described by the crown fuel particle characteristics; and (iv) energy transfer (gain and losses) to the crown fuels. Fuel particle temperature increase is determined through an energy balance relating heat absorption to fuel particle temperature. The final model output is the temperature of the crown fuel particles, which upon reaching ignition temperature are assumed to ignite. CFIM predicts the ignition of crown fuels but does not determine the onset of crown fire spread per se. The coupling of the CFIM with models determining the rate of propagation of crown fires allows for the prediction of the potential for sustained crowning. CFIM has the potential to be implemented in fire management decision support systems.
Heterogeneity in fire severity within early season and late season prescribed burns in a mixed-conifer forest
Authors: Knapp Eric E. , Keeley Jon E.
Published: March 2006

Structural heterogeneity in forests of the Sierra Nevada was historically produced through variation in fire regimes and local environmental factors. The amount of heterogeneity that prescription burning can achieve might now be more limited owing to high fuel loads and increased fuel continuity. Topography, woody fuel loading, and vegetative composition were quantified in plots within replicated early and late season burn units. Two indices of fire severity were evaluated in the same plots after the burns. Scorch height ranged from 2.8 to 25.4 m in early season plots and 3.1 to 38.5 m in late season plots, whereas percentage of ground surface burned ranged from 24 to 96% in early season plots and from 47 to 100% in late season plots. Scorch height was greatest in areas with steeper slopes, higher basal area of live trees, high percentage of basal area composed of pine, and more small woody fuel. Percentage of area burned was greatest in areas with less bare ground and rock cover (more fuel continuity), steeper slopes, and units burned in the fall (lower fuel moisture). Thus topographic and biotic factors still contribute to the abundant heterogeneity in fire severity with prescribed burning, even under the current high fuel loading conditions. Burning areas with high fuel loads in early season when fuels are moister may lead to patterns of heterogeneity in fire effects that more closely approximate the expected patchiness of historical fires.
Bromus tectorum cover mapping and fire risk
Authors: Link Steven O. , Keeler Carson W. , Hill Randal W. , Hagen Eric
Published: March 2006

Fire risk in western North America has increased with increasing cover of Bromus tectorum, an invasive alien annual grass. The relationship between B. tectorum cover and fire risk was determined in a historically burned Artemisia tridentata-Poa secunda shrub–steppe community where B. tectorum cover ranged from 5 to 75%. Fire risk ranged from ~46% with an average of 12% B. tectorum cover to 100% when B. tectorum cover was greater than 45% based on prediction confidence limits. Reflectance of the green and red bands of aerial photographs were related to senescent B. tectorum cover to create fine resolution B. tectorum cover and fire risk maps. This assessment technique will allow land managers to prioritize lands for restoration to reduce fire risk in the shrub-steppe.
Influence of heat and smoke treatments on the germination of six leguminous shrubby species
Authors: Rivas Mercedes , Reyes Otilia , Casal Mercedes
Published: March 2006

The effect of high temperatures and smoke on germination was tested on the shrubland Leguminosae species, Adenocarpus lainzii, Cytisus scoparius, Cytisus striatus, Genista berberidea, Genista triacanthos, and Pterospartum tridentatum, which are abundant and widely distributed throughout the north-western Iberian Peninsula. Light thermal shocks (80°C, 5 min and 80°C, 10 min) and medium thermal shocks (110°C, 5 min and 110°C, 10 min) stimulated seed germination in C. striatus, A. lainzii, and P. tridentatum. The treatments 80°C, 10 min and 110°C, 5 min stimulated germination in C. scoparius but only 110°C, 5 min did so in G. berberidea and G. triacanthos. The intense thermal shocks (150°C, 5 min and 150°C, 10 min) inhibited germination in all of the species studied but the inhibition effect was already detectable at 110°C, 10 min in G. berberidea. From the results, it was impossible to relate the different levels of smoke used to the variations in the germination response of the species studied. The increase in the germination level after fire was more important in C. scoparius, C. striatus, A. lainzii, and G. triacanthos, which are non-resprouters.
Science, technology, and human factors in fire danger rating: the Canadian experience.
Authors: Taylor Stephen W. , Alexander Martin E.
Published: March 2006

The present paper reviews the development of the Canadian Forest Fire Danger Rating System (CFFDRS) and its implementation in Canada and elsewhere, and suggests how this experience can be applied in developing fire danger rating systems in other forest or wildland environments. Experience with the CFFDRS suggests that four key scientific, technological, and human elements need to be developed and integrated in a national forest fire danger rating system. First among these is a sustained program of scientific research to develop a system based on relationships between fire weather, fuels, and topography, and fire occurrence, behavior, and impact appropriate to the fire environment. Development of a reliable technical infrastructure to gather, process, and archive fire weather data and to disseminate fire weather forecasts, fire danger information, and fire behavior predictions within operational agencies is also important. Technology transfer and training in the use of fire danger information in fire operations are necessary, as are cooperation and communication between fire management agencies to share resources and set common standards for information, resources, and training. These elements must be appropriate to the needs and capabilities of fire managers, and must evolve as fire management objectives change. Fire danger systems are a form of media; system developers should be careful not to overemphasize scientific and technological elements at the expense of human and institutional factors. Effective fire danger systems are readily assimilated by and influence the organizational culture, which in turn influences the development of new technologies. Most importantly, common vision and a sense of common cause among fire scientists and fire managers are needed for successful implementation of a fire danger rating system.
Prediction of delayed mortality of fire-damaged ponderosa pine following prescribed fires in eastern Oregon, USA
Authors: Thies Walter G. , Westlind Douglas J. , Loewen Mark , Brenner Greg
Published: March 2006

Prescribed burning is a management tool used to reduce fuel loads in western interior forests. Following a burn, managers need the ability to predict the mortality of individual trees based on easily observed characteristics. Astudy was established in six stands of mixed-age ponderosa pine (Pinus ponderosa Dougl. ex Laws.) with scattered western junipers at the south end of the Blue Mountains near Burns, Oregon, USA. Stands were thinned in either 1994 or 1995. Three treatments, a fall burn, a spring burn, and an unburned control, were randomly assigned to 12-ha experimental units within each stand. Prescribed burns occurred during mid-October of 1997 or mid-June of 1998 and were representative of operational burns, given weather and fuel conditions. Within each experimental unit, six 0.2-ha plots were established to evaluate responses to the burns. Ponderosa pine plot trees (n =3415) alive 1 month after the burns were evaluated and observed for four growing seasons. Nine fire damage and tree morphological variables were evaluated by logistic regression. A five-factor full model and a two-factor reduced model are presented for projecting probability of mortality. Significant variables in the full model included measures of crown, bole, and basal damage.
Frequency and causes of kangaroo - vehicle collisions on an Australian outback highway
Authors: Klöcker Ulrike , Croft David B. , Ramp Daniel
Published: March 2006

Kangaroo–vehicle collisions are frequent on Australian highways. Despite high economic costs, detrimental effects on animal welfare, and potential impacts on population viability, little research has been done to investigate the impact of road mortality on kangaroo populations, where and why accidents occur, and how the collisions can be mitigated. We therefore collected data on species (Macropus rufus, M. giganteus, M. fuliginosus, M. robustus), sex and age of kangaroos killed on a 21.2-km bitumenised section of outback highway over 6 months in far western New South Wales, Australia. The spatial and temporal distribution of road-killed kangaroos was investigated in relation to the cover and quality of road-side vegetation, road characteristics, the density of kangaroos along the road, climatic variables and traffic volume. A total of 125 kangaroos were found killed on the road at a rate of 0.03 deaths km–1 day–1. Grey kangaroos of two species (M. giganteus, M. fuliginosus) were under-represented in the road-kill sample in comparison with their proportion in the source population estimated during the day. No bias towards either sex was found. The age structure of road-killed kangaroos was similar to age structures typical of source kangaroo populations. Road-kills mainly occurred in open plains country. In road sections with curves or stock races, road-kill frequencies were higher than expected. Greater cover and greenness of roadside vegetation at the verge probably attracted kangaroos to the road and variation in this vegetation affected the spatial distribution of road-kills. The temporal distribution of road-kills was positively correlated with the volume of night-time traffic. The probability of a kangaroo–vehicle collision increased exponentially with traffic volume. Results are discussed in relation to the potential for mitigation of kangaroo–vehicle collisions.
Estimating the age of kangaroos using eye lens weight
Authors: McLeod S. R. , Druhan J. P. , Hacker R. B.
Published: March 2006

A method for estimating the age of red kangaroos (Macropus rufus), eastern grey kangaroos (M. giganteus) and western grey kangaroos (M. fuliginosus) is described. The method uses the dried weight of the eye lens to estimate age. The method is suitable for estimating the age of kangaroos of all ages.
Meteorological effects on the activity of the giant burrowing frog (Heleioporus australiacus) in south-eastern Australia
Authors: Penman Trent D. , Lemckert Frank L. , Mahony Michael J.
Published: March 2006

Activity of amphibians is strongly related to meteorological conditions. The threatened giant burrowing frog is rarely encountered, even when it is known to be present in an area. To improve its detectability and so improve our ability to manage the species we wanted to determine the conditions under which this species is active. Thirty-three frogs were tracked over a 2-year period, their location determined daily and activity measured as the proportion of frogs moved from the previous day. Animals were found to be active throughout the year and activity was associated with rainfall, humidity, temperature and wind strength. The results suggest that surveys for this species should be carried out after rainfall of at least 5mm, when temperatures are above 8°C, relative humidity above 60% and in still or light wind conditions.
Movements of female white-tailed deer to bait sites in West Virginia, USA
Authors: Campbell Tyler A. , Langdon Christopher A. , Laseter Benjamin R. , Ford W. Mark , Edwards John W. , Miller Karl V.
Published: March 2006

We present a comparison of movements of adult female white-tailed deer (Odocoileus virginianus) in response to seasonal bait sites in the central Appalachians of West Virginia, USA. Our objectives were to compare bait-site use among seasons, evaluate home-range and core-area sizes between baiting and non-baiting periods, and compare distance from the geographic centres of activity to nearest bait site between baiting and non-baiting periods. From June 2000 to May 2001, we radio-monitored 52 deer and determined their use of 29 seasonal bait sites with automated camera systems. We collected 6461 locations and 1333 photographic observations of radio-collared deer. Bait-site use did not differ among four seasonal baiting periods. Additionally, home-range and core-area sizes did not differ between baiting and non-baiting periods. However, deer shifted their centres of activity closer to bait sites during baiting periods. High variability in deer behaviour should be considered when implementing deer-management activities that require all deer to use bait sites, such as infrared-triggered camera surveys.
Fertility control in female eastern grey kangaroos using the GnRH agonist deslorelin. 1. Effects on reproduction
Authors: Herbert C. A. , Trigg T. E. , Cooper D. W.
Published: March 2006

Eastern grey kangaroos are widespread on the east coast of Australia and frequently reach high densities in reserves and parkland near urban areas. Management of these populations is highly contentious and non-lethal fertility-control technologies are sought as an alternative option to manage population size. This study evaluated the potential of slow-release gonadotrophin-releasing hormone agonist (deslorelin) implants to inhibit reproduction in female kangaroos. Deslorelin treatment effectively inhibited reproduction in adult females for periods of 559 ± 111 days (n = 6) and 651 ± 21 days (n = 5) after administration of one or two 10-mg implants respectively. Animals treated with the lower dosage tended to resume breeding earlier than those that received a total of 20 mg of deslorelin (minimum duration of 18 months). Deslorelin treatment had no effect on blastocyst reactivation in a single treated female and repeat treatment had no negative side-effects. This study has demonstrated that slow-release deslorelin implants can successfully inhibit reproduction for extended periods in the female eastern grey kangaroos. This approach may have potential application in reproductive management of problem kangaroo populations.
Fertility control in female eastern grey kangaroos using the GnRH agonist deslorelin. 2. Effects on behaviour
Authors: Woodward R. , Herberstein M. E. , Herbert C. A.
Published: March 2006

In recent years fertility control has been proposed as an ethically acceptable alternative to lethal control techniques when managing overabundant kangaroo populations. A promising non-steroidal, non-immunological approach to contraception in female kangaroos involves the use of slow-release implants containing the gonadotrophin-releasing hormone (GnRH) agonist deslorelin. The practicality of using deslorelin implants as a management option is dependant on its effective inhibition of reproduction without negative physical or behavioural side-effects. This study investigated the behavioural effects of deslorelin implants in female eastern grey kangaroos. Treatment had no detectable effects on crepuscular activity. Alterations in the frequency of sexual interactions were observed in deslorelin-treated females, with a behavioural oestrus induced ~3 days after combined removal of pouch young and deslorelin administration. Copulation was observed during this early oestrous period, but conception was not achieved and pouch young were not observed in any treated females. Control females gave birth within 69.6 ± 10.4 days (mean ± s.e.m., n = 9) of placebo implant administration. The first births observed in treated animals were on Days 510, 637 and 643 after treatment. The remaining seven treated animals had not bred by the end of the study, a period of 647 days.
Association of common brown froglets, Crinia signifera, with clearcut forest edges in Tasmania, Australia
Authors: Baker Sue , Lauck Bonnie
Published: March 2006

We examined the response of the common brown froglet, Crinia signifera, to recently clearcut forest edges in Tasmanian wet Eucalyptus obliqua forest. We established transects of pitfall traps crossing coupe edges, within coupes, and within mature forest interiors (riparian and non-riparian) at three study sites. Pitfall captures of C. signifera were greatest at the immediate logged forest edge (which corresponded with a firebreak constructed as part of standard clearfell, burn and sow silvicultural practices in Tasmania). Capture rates were lower in both the coupe interior and the immediate unlogged forest edge and declined to negligible numbers in the unlogged forest interior. Edge penetration was estimated to be generally 50–100 m. We suggest that Tasmania’s current management of wet forest may provide additional habitat for C. signifera by changing the age structure of the forest and providing additional forest edge/firebreak habitat. However, C. signifera is common and disturbance tolerant, and thus these findings should not be extrapolated to other Australian frog species that may be disadvantaged by current logging practices.
Change in the diet of sooty owls (Tyto tenebricosa) since European settlement: from terrestrial to arboreal prey and increased overlap with powerful owls
Authors: Bilney Rohan J. , Cooke Raylene , White John
Published: March 2006

The current diet of the sooty owl (Tyto tenebricosa) was determined by analysing freshly regurgitated pellets collected beneath their roosting sites in East Gippsland, Victoria. Comparisons were then made with: (i) prehistoric and historic diet from bone deposits found in cave roosts, and (ii) diet of a sympatric owl species, the powerful owl (Ninox strenua). Sooty owls consumed a large array of terrestrial mammal species before European settlement, but only three terrestrial species were detected in their current diet, a reduction of at least eight species since European settlement. To compensate, sooty owls have increased their consumption of arboreal prey from 55% to 81% of their diet. Arboreal species are also a major component of the powerful owl diet and this prey shift by sooty owls has increased dietary overlap between these two species. Predation by foxes (Vulpes vulpes) and other feral species is likely to have reduced the amount of terrestrial prey available to sooty owls since European settlement. Investigation of changes in the diet of sooty owls may offer a unique monitoring system for evaluating the ability of fox-control strategies to influence increases in numbers of critical-weight-range mammals.
Accuracy and precision of grey-headed flying-fox (Pteropus poliocephalus) flyout counts
Authors: Forsyth David M. , Scroggie Michael P. , McDonald-Madden Eve
Published: March 2006

The principal method for estimating the abundance of bats in roosts is to count the number of bats exiting the roost at dusk (‘flyout counts’). We hypothesised that the accuracy and precision of flyout counts decrease non-linearly as the number of bats moving per unit of time increases, and that accuracy increases with observer experience. To test these hypotheses, we filmed grey-headed flying-foxes (Pteropus poliocephalus) exiting a roost in Melbourne on three consecutive evenings. The film was slowed and the number of flying-foxes flying-out in 30-s intervals was counted and assumed to be the true abundance. Thirteen other observers independently counted the number of flying-foxes flying-out in real time. We formulated our hypotheses into candidate models and compared support for these models using information-theoretic methods. Non-linear models had much greater support than linear models for all three flyouts. There was undercounting in two flyouts and overcounting in the third. There was good support for an effect of observer experience in one of the flyouts, but less support in the others. Precision declined as the true abundance increased in all three flyout counts. Our results indicate that accuracy, precision and observer effects vary with the dynamics of each flyout, and suggest that under some conditions flyout counts will often provide both inaccurate and imprecise estimates of abundance.