bluuebunny/crossref_metadata_2025 huggingface dataset:
Characterization of water exchange and two-phase flow in porous gas diffusion materials by hydrogen-deuterium contrast neutron radiography
Authors: Manke Ingo , Hartnig Christoph , Kardjilov Nikolay , Messerschmidt Matthias , Hilger André , Strobl Markus , Lehnert Werner , Banhart John
Published: June 2008

Liquid water exchange in two-phase flows within hydrophobic porous gas diffusion materials of polymer electrolyte membrane fuel cells was investigated spatially resolved with H–D contrast neutron radiography. A commonly used one-phase model is sufficient to describe water exchange characteristics at low water production rates. At higher rates, however, a significantly higher exchange velocity is found than predicted by a simple model. A new model for the water transport is derived based on an eruptive mechanism guided by Haines jumps, which is supported by recent experimental findings and leads to a very good agreement with the experiments.
Photovoltaic-thermoelectric hybrid systems: A general optimization methodology
Authors: Kraemer D. , Hu L. , Muto A. , Chen X. , Chen G. , Chiesa M.
Published: June 2008

The present work outlines a general optimization methodology for hybrid systems consisting of photovoltaic (PV) and thermoelectric (TE) modules. Exemplarily, hybrid systems with hydrogenated microcrystalline silicon, hydrogenated amorphous silicon, and bulk heterojunction polymer thin-film solar cell for different solar TE generator efficiencies are evaluated. The proposed methodology optimizes the partitioning of the solar spectrum in order to yield the maximum conversion efficiency of a PV-TE hybrid system with a solar cell operating at ambient temperature.
On the efficacy of imploding plasma liners for magnetized fusion target compression
Authors: Parks P. B.
Published: June 2008

A new theoretical model is formulated to study the idea of merging a spherical array of converging plasma jets to form a “plasma liner” that further converges to compress a magnetized plasma target to fusion conditions [Y. C. F. Thio et al., “Magnetized target fusion in a spheroidal geometry with standoff drivers,” Current Trends in International Fusion Research II, edited by E. Panarella (National Research Council Canada, Ottawa, Canada, 1999)]. For a spherically imploding plasma liner shell with high initial Mach number (M=liner speed/sound speed) the rise in liner density with decreasing radius r goes as ρ∼1∕r2, for any constant adiabatic index γ=dlnp∕dlnρ. Accordingly, spherical convergence amplifies the ram pressure of the liner on target by the factor A∼C2, indicating strong coupling to its radial convergence C=rm∕R, where rm(R)=jet merging radius (compressed target radius), and A=compressed target pressure/initial liner ram pressure. Deuterium-tritium (DT) plasma liners with initial velocity ∼100km∕s and γ=5∕3, need to be hypersonic M∼60 and thus cold in order to realize values of A∼104 necessary for target ignition. For optically thick DT liners, T<2eV, n>1019–1020cm−3, blackbody radiative cooling is appreciable and may counteract compressional heating during the later stages of the implosion. The fluid then behaves as if the adiabatic index were depressed below 5∕3, which in turn means that the same amplification A=1.6×104 can be accomplished with a reduced initial Mach number M≈12.7(γ−0.3)4.86, valid in the range (10<M<60). Analytical calculations indicate that the hydrodynamic efficiency for plasma liners assembled by current and anticipated plasma jets is <4%. A new similarity model for fusion α-particle heating of the collapsed liner indicates that “spark” ignition of the DT liner fuel does not appear to be possible for magnetized fusion targets with typical threshold values of areal density ρR<0.02gcm−2.
Performance enhancement of GaN ultraviolet avalanche photodiodes with p-type δ-doping
Authors: Bayram C. , Pau J. L. , McClintock R. , Razeghi M.
Published: June 2008

High quality δ-doped p-GaN is used as a means of improving the performance of back-illuminated GaN avalanche photodiodes (APDs). Devices with δ-doped p-GaN show consistently lower leakage current and lower breakdown voltage than those with bulk p-GaN. APDs with δ-doped p-GaN also achieve a maximum multiplication gain of 5.1×104, more than 50 times higher than that obtained in devices with bulk p-GaN. The better device performance of APDs with δ-doped p-GaN is attributed to the higher structural quality of the p-GaN layer achieved via δ-doping.
Synthesis and electrical properties of TiSi2 nanocables
Authors: Zou Chenxia , Zhang Xinzheng , Jing Guangyin , Zhang Jingmin , Liao Zhimin , Yu Dapeng
Published: June 2008

Uniform TiSi2 nanocables were synthesized on large substrates using a simple physical vapor deposition method. X-ray diffraction, scanning electron microscopy, and transmission electronic microscopy were employed to characterize the samples. It reveals that the as-grown TiSi2 nanocables are of high quality single crystal inside with thin amorphous SiO2 sheathing layer. Electrical properties of these core-shell structure nanowires are also presented. Insulativity of the outer layer and stable metallic characters of the inside single crystal TiSi2 were observed. Moreover, carrying capacity of current density is up to 1011A∕m2. The nanoscale structure and excellent electrical performance make the TiSi2 nanocables good candidate for electrical interconnection in potential nanodevices.
Three-dimensional morphology of nanoporous gold
Authors: Fujita Takeshi , Qian Li-Hua , Inoke Koji , Erlebacher Jonah , Chen Ming-Wei
Published: June 2008

We report transmission electron tomography of nanoporous gold fabricated by chemically dealloying Au35Ag65 films. A number of algorithms were employed to quantitatively characterize the complex three-dimensional nanoporous structure. It was found that gold ligaments and nanopore channels are topologically and morphologically equivalent, i.e., they are inverses of each other in three-dimensional space. Statistical analysis reveals that this bicontinuous nanostructured material is actually quasiperiodic and has, on average, a near zero surface curvature. These quantitative measurements will help in understanding the structural stability of nanoporous gold and in modeling its physical and chemical performances.
Domain wall motion in epitaxial Pb(Zr,Ti)O3 capacitors investigated by modified piezoresponse force microscopy
Authors: Yang S. M. , Jo J. Y. , Kim D. J. , Sung H. , Noh T. W. , Lee H. N. , Yoon J.-G. , Song T. K.
Published: June 2008

We investigated the time-dependent domain wall motion of epitaxial PbZr0.2Ti0.8O3 capacitors 100nm thick using modified piezoresponse force microscopy (PFM). We obtained successive domain evolution images reliably by combining the PFM with switching current measurements. We observed that domain wall speed (v) decreases with increases in domain size. We also observed that the average value of v, obtained under applied electric field (Eapp), showed creep behavior, i.e., ⟨v⟩∼exp[−(E0∕Eapp)μ] with an exponent μ of 0.9±0.1 and an activation field E0 of about 700kV∕cm.
Mechanical behavior of ultralow-dielectric-constant mesoporous amorphous silica
Authors: Gungor M. Rauf , Watkins James J. , Maroudas Dimitrios
Published: June 2008

Using molecular-dynamics simulations, we examine the mechanical behavior of mesoporous amorphous silicas that are considered as ultralow-dielectric-constant materials in microelectronics. We study structures with a regular array of spherical pores and densities between 88% and 72% of the amorphous silica normal density. We find that the Young modulus depends on density according to a sublinear power-law scaling relationship and decreases with decreasing mesopore size. Upon uniaxial compression, an elastic instability is triggered in structures with less-than-critical density or mesopore size.
Carrier lifetimes in type-II InAs quantum dots capped with a GaAsSb strain reducing layer
Authors: Jang Y. D. , Badcock T. J. , Mowbray D. J. , Skolnick M. S. , Park J. , Lee D. , Liu H. Y. , Steer M. J. , Hopkinson M.
Published: June 2008

Carrier lifetimes have been measured for long-wavelength emitting InAs quantum dots (QDs) capped with a thin GaAsSb layer. Above a critical Sb composition, a type-II system is formed, resulting in an increase in the carrier lifetime. The carrier lifetime in a strongly type-II structure is increased by a factor ∼54 in comparison to the lifetime in a type-I structure. In addition, the type-II carrier lifetime varies across the inhomogeneously broadened ground-state emission, while the type-I QD lifetime is invariant.
Ductile Fe–Nb–B bulk metallic glass with ultrahigh strength
Authors: Yao J. H. , Wang J. Q. , Li Y.
Published: June 2008

The authors report a simple Fe-based Fe71Nb6B23 ternary bulk metallic glass with a record high strength of 4.85GPa as well as an appreciable compressive plastic strain of 1.6%. This finding is associated with the unique attribute of the alloying element Nb, which favors the formation of a networklike structure and holds high Poisson’s ratio. A fracture feature with a combination of vein pattern and nanoscale corrugations under compression is clearly characterized in this glass. The fractographic observations correlate well with the observed improvements in plasticity.
Effect of stress on the transformation of Ni2Si into NiSi
Authors: Mangelinck Dominique , Hoummada Khalid
Published: June 2008

In situ isothermal x-ray diffraction were performed on Ni∕a-Si and Ni(5%Pt)/(100)Si. In the Ni∕a-Si samples, there is a time delay between the formation of NiSi and the end of the growth of Ni2Si. In the Ni(5%Pt)/(100)Si, the growth of the NiSi phase is accelerated after a time delay. The time delay is related to the strain relaxation in Ni2Si; i.e., the growth of NiSi starts (pure Ni case) or is accelerated [Ni(Pt) case] when most of the strain in Ni2Si is relaxed. This shows that the intrinsic stress associated with the growth of silicide influence the reactive diffusion.
Influence of tip-sample interaction in a time-domain terahertz scattering near field scanning microscope
Authors: Thoma A. , Dekorsy T.
Published: June 2008

Apertureless near field measurements with a metallic tip are performed in the terahertz frequency range. Lateral scans are recorded for different time delays within a terahertz pulse. The forward scattered terahertz signal strongly depends on the time delay. At larger time delays, the tip-sample interaction leads to additional structures in the scan that do not correspond to a change in topography or dielectric function.
Efficient 13.5nm extreme ultraviolet emission from Sn plasma irradiated by a long CO2 laser pulse
Authors: Tao Y. , Tillack M. S. , Sequoia K. L. , Burdt R. A. , Yuspeh S. , Najmabadi F.
Published: June 2008

The effect of pulse duration on in-band (2% bandwidth) conversion efficiency (CE) from a CO2 laser to 13.5nm extreme ultraviolet (EUV) light was investigated for Sn plasma. It was found that high in-band CE, 2.6%, is consistently obtained using a CO2 laser with pulse durations from 25to110ns. Employing a long pulse, for example, 110ns, in a CO2 laser system used in an EUV lithography source could make the system significantly more efficient, simpler, and cheaper as compared to that using a short pulse of 25ns or shorter.
Anisotropic damping of longitudinal optical phonon-plasmon coupling modes of InN films
Authors: Ishitani Yoshihiro , Fujiwara Masayuki , Wang Xinqiang , Che Song-Bek , Yoshikawa Akihiko
Published: June 2008

The energy broadenings of the higher energy branch of the longitudinal optical (LO) phonon-plasmon coupling modes for E1(LO) and A1(LO) are analyzed for InN films by infrared reflectance and spectroscopic ellipsometry. Larger broadening for the vibration parallel to c of A1(LO)-plasmon coupling is found with the decrease in electron density. This phenomenon is caused by the plasmon lifetime anisotropy, and is attributed to the reduction in crystal defects causing isotropic carrier scattering and the remaining of defects along the c axis such as threading dislocations and columnar grain boundaries.
A micromachined optical double well for thermo-optic switching via resonant tunneling effect
Authors: Zhu W. M. , Zhang X. M. , Liu A. Q. , Cai H. , Jonathan T. , Bourouina T.
Published: June 2008

This letter presents the thermo-optic switching characteristics of an optical double-well structure, which has a high-low-high-low-high refractive index construct formed by micromachined silicon prisms and air gaps. Analysis shows such structure features full transmission (i.e., on state) and requires low refractive index change for switching function. The device is fabricated on silicon-on-isolator wafer using deep etching process. In experiment, it measures a switching speed of 1μs and an extinction ratio of 30dB. Compared with the other micromachined switches, this device utilizes different physical principle and processes various merits such as fast switching speed and low power consumption.
Large tunneling magnetoresistance in a field-effect transistor with a nanoscale ferromagnetic gate
Authors: Bae J.-U. , Lin T.-Y. , Yoon Y. , Kim S. J. , Imre A. , Porod W. , Reno J. L. , Bird J. P.
Published: June 2008

We demonstrate large, and hysteretic, tunneling magnetoresistance (MR) in field-effect transistors (FETs), when their usual nonmagnetic gate is replaced with a nanoscale ferromagnet. Our analysis indicates that the enhanced MR in the tunneling regime results from the ability of the fringing magnetic fields, which emanate from the nanomagnet into the FET channel, to provide an additional modulation of the electrostatic barrier induced by the applied gate voltage. The ability of this device to detect changes in magnetization may eventually allow the implementation of reprogrammable devices for universal logic and memory applications.
Evidence for electromagnetic granularity in the polycrystalline iron-based superconductor LaO0.89F0.11FeAs
Authors: Yamamoto A. , Jiang J. , Tarantini C. , Craig N. , Polyanskii A. A. , Kametani F. , Hunte F. , Jaroszynski J. , Hellstrom E. E. , Larbalestier D. C. , Jin R. , Sefat A. S. , McGuire M. A. , Sales B. C. , Christen D. K. , Mandrus D.
Published: June 2008

The recently discovered oxypnictide superconductors are layered, low carrier density compounds with many similarities to the high-Tc cuprates. An important question is whether they also exhibit weak-coupling across randomly oriented grain boundaries. In this work we show considerable evidence for such weak coupling by study of the dependence of magnetization in bulk and powdered samples. Bulk sample magnetization curves show very little hysteresis while remanent magnetization shows almost no sample size dependence, even after powdering. We conclude that these samples exhibit substantial electromagnetic granularity on a scale approximating the grain size, though we cannot yet determine whether this is intrinsic or extrinsic.
Soil N process inhibitors alter nitrogen leaching dynamics in a pumice soil
Authors: Menneer John C. , Ledgard Stewart , Sprosen Mike
Published: June 2008

A field lysimeter experiment, using a free-draining pumice soil, was carried out to investigate the effect of different soil nitrogen (N) process inhibitors on the fate of 15N-labelled cow urine. The treatments were a urease inhibitor (Agrotain; N-(n-butyl) thiophosphoric triamide), 2 nitrification inhibitors (dicyandiamide, DCD; 4-methylpyrazole, 4MP), a combination (DCD+Agrotain), a urine control, and a nil urine. The inhibitors were mixed with cow urine, which was then applied in a single application (equivalent to 775 kg N/ha) to lysimeters in autumn and monitored over the following 196 days. DCD and 4MP similarly reduced nitrate leaching by 59%, from 114 to 47 kg N/ha compared with the urine control. Of the DCD applied, 58% of it (8.7 kg/ha) was recovered in leachate, and represented an N loss of 5.8 kg/ha. The presence of Agrotain reduced ammonia (NH3-N) emissions by 64% (equivalent to 70 kg N/ha) over the short term (first 20 days), but led to large leaching losses of urea-N (25 kg N/ha) over the medium term (76 days). The Agrotain-DCD combination resulted in even larger losses of urea-N (45 kg N/ha). The major N component measured in leachate (below 450 mm) was ammonium-N, which constituted about 60% of the average total N (205 kg N/ha) leached. Ammonium-N leaching was rapid and almost entirely driven by macropore flow processes. Further research is required in deeper soil profiles, and in relation to climatic risk of high early rainfall on fresh urine patches, to determine the importance of macropore processes on N loss under typical on-farm soil conditions.
Soil organic carbon stocks in saline and sodic landscapes
Authors: Wong Vanessa N. L. , Murphy Brian W. , Koen Terry B. , Greene Richard S. B. , Dalal Ram C.
Published: June 2008

Increasing salinity (high levels of water-soluble salts) and sodicity (high levels of exchangeable sodium) are serious land degradation issues worldwide. In Australia, salinity and sodicity affect a large proportion of the landscape and often coincide with agricultural land. Despite the areal extent of salt-affected soils, both worldwide and in Australia, few data exist on soil organic carbon (SOC) stocks in these areas. For this study, the level of SOC was determined in scalded (bare areas without vegetation), scalded-eroded, vegetated, and revegetated (i.e. sown pasture) soil profiles from 2 sites in the Southern Tablelands region of New South Wales, Australia. SOC concentration was significantly higher in the profiles that were vegetated with native pasture (1.96–2.71% in the 0–0.05 m layer) or revegetated with sown pasture (2.35% in the 0–0.05 m layer), and lower in those profiles that were scalded (1.52% in the 0–0.05 m layer) or scalded-eroded (0.16–0.30% in the 0–0.05 m layer). These lower SOC levels are reflected throughout the profiles of the scalded and scalded-eroded soils. The soil carbon stocks to 0.30 m are also much lower in the scalded and scalded-eroded soils that have been affected by salinity and sodicity. The profiles that were vegetated with native pasture had carbon stocks to 0.30 m of 35.2–53.5 t/ha, while the sown pasture had 42.1 t/ha. This compares with the scalded profiles with 19.8 t/ha and the scalded-eroded profiles with 7.7–11.4 t/ha to 0.30 m. The presence of vegetation ameliorates several soil properties and results in the differences in SOC and other soil properties between scalded and vegetated profiles at the surface and at depth.
Losses of nitrogen fertiliser under oil palm in Papua New Guinea: 1. Water balance, and nitrogen in soil solution and runoff
Authors: Banabas Murom , Turner Max A. , Scotter David R. , Nelson Paul N.
Published: June 2008

Nitrogen (N) fertiliser is an important and expensive input to oil palm in Papua New Guinea. Of about 3000 mm/year of rainfall, about 1300 mm is lost as evaporation. This leaves an excess of >1000 mm/year lost as surface runoff and/or deep drainage, and with it the potential for N loss. Approximately 11% of rainfall reached the ground as stem flow. Throughfall was generally lowest near the trunk and highest where canopies overlapped, but random spatial variability was large. The difference between the measured rainfall and stem flow plus throughfall was 6%, indicating relatively little interception.
Surface runoff from the volcanic ash soils was 6% of rainfall at one site, but only 1.4% at the other. Less than 2% of the applied N was lost in the surface runoff after an ammonium chloride application. Calculations of N leaching losses made using suction cup data and the water balance indicated that significant losses occur, but the estimates were not reliable due to the huge spatial variability in the suction cup and throughfall data. Therefore, another technique is needed to study N leaching in oil palm plantations.
Losses of nitrogen fertiliser under oil palm in Papua New Guinea: 2. Nitrogen transformations and leaching, and a residence time model
Authors: Banabas Murom , Scotter David R. , Turner Max A.
Published: June 2008

Nitrogen fertiliser is an expensive input to oil palm in Papua New Guinea, and prone to leaching due to the about 3000 mm/year of rainfall. Transfer function theory is used to describe this leaching, and to devise ways of reducing it. Four variants of a leaching experiment were conducted at 2 sites to parameterise and check the theory. The experiment involved the application of ammonium chloride to an area of 25 m2, and then from 6 days to 5 months later taking soil samples at 200-mm intervals down to 2 m depth and analysing them for chloride, ammonium, and nitrate. Background concentrations were obtained by contemporaneous sampling nearby. In one variant of the experiment 353 mm of rain in 6 days moved nearly half the applied nitrogen to below 400 mm depth. Nitrification was rapid, with ammonium half-lives ranging from 2 to 16 days once the soil was wet. The theory is used to demonstrate how the fertiliser residence time in the root-zone can be increased by applying it in certain months and about 2 m from the trunk where there is less throughfall.
Evaluation of long-term soil management practices using key indicators and soil quality indices in a semi-arid tropical Alfisol
Authors: Sharma K. L. , Grace J. Kusuma , Mandal Uttam Kumar , Gajbhiye Pravin N. , Srinivas K. , Korwar G. R. , Hima Bindu V. , Ramesh V. , Ramachandran Kausalya , Yadav S. K.
Published: June 2008

Alfisol soils of rainfed semi-arid tropics (SAT) are degrading due to several physical, chemical, and biological constraints. Appropriate soil-nutrient management practices may help to check further soil degradation. A long-term experiment comprising tillage and conjunctive nutrient use treatments under a sorghum (Sorghum bicolor (L.) Moench)–mung bean (Vigna radiata (L.) Wilkzec) system was conducted during 1998–05 on SAT Alfisols (Typic Haplustalf) at the Central Research Institute for Dryland Agriculture, Hyderabad. The study evaluated soil and nutrient management treatments for their long-term influence on soil quality using key indicators and soil quality indices (SQI). Of the 21 soil quality parameters considered for study, easily oxidisable N (KMnO4 oxidisable-N), DTPA extractable Zn and Cu, microbial biomass carbon (MBC), mean weight diameter (MWD) of soil aggregates, and hydraulic conductivity (HC) played a major role in influencing the soil quality and were designated as the key indicators of ‘soil quality’ for this system. The SQI obtained by the integration of key indicators varied from 0.66 (unamended control) to 0.83 (4 Mg compost + 20 kg N as urea) under conventional tillage (CT), and from 0.66 (control) to 0.89 (4 Mg compost + 2 Mg gliricidia loppings) under reduced tillage (RT). Tillage did not influence the SQI, whereas the conjunctive nutrient-use treatments had a significant effect. On an average, under both CT and RT, the sole organic treatment improved the soil quality by 31.8% over the control. The conjunctive nutrient-use treatments improved soil quality by 24.2–27.2%, and the sole inorganic treatment by 18.2% over the control. Statistically, the treatments improved soil quality in the following order: 4 Mg compost + 2 Mg gliricidia loppings > 2 Mg Gliricidia loppings + 20 kg N as urea = 4 Mg compost + 20 kg N as urea > 40 kg N as urea. The percentage contribution of the key indicators towards the SQI was: MBC (28.5%), available N (28.6%), DTPA-Zn (25.3%), DTPA-Cu (8.6%), HC (6.1%), and MWD (2.9%). The functions predicting the changes in yield and sustainability yield index with a given change in SQI were also determined.
Improved drainage and greater air-filled porosity of raised beds in south-western Victoria
Authors: Holland J. E. , White R. E. , Edis R.
Published: June 2008

Crop production in south-western Victoria has historically been constrained by waterlogging. As a result raised beds have recently become a popular tillage method on soils prone to waterlogging. Soil water properties, air-filled porosity, plant dry matter, and grain yield were compared for raised beds and conventional cultivation treatments during 2003 and 2004. Although rainfall was less than the long-term average, over the whole period the raised beds had consistently lower water content and drained faster than the conventional cultivation. Air-filled porosity was greater and above the critical value of 10% for longer in the raised beds (e.g. in 2004 air-filled porosity was >10% for 69 days longer in the raised beds). Benefits on the raised bed soil (such as greater soil aeration) were probably due to the increased depth to the B horizon and the soil surface topography created by regular furrows. No waterlogging was observed in 2003 and the crop on the conventional cultivation produced significantly more dry matter. Although visible waterlogging of the crop on the conventional cultivation was observed in 2004, the crop on the raised beds was not affected. Despite the different response in growth for each treatment, there was no significant difference in grain yield in either year. Nevertheless, it is predicted that raised beds should provide a well-drained and aerated soil that maintains crop productivity under average or greater rainfall in south-western Victoria.
Fire ignitions related to radar reflectivity patterns in Arizona and New Mexico
Authors: Hall Beth L.
Published: June 2008

Over 5400 lightning-ignited wildfires were detected on federal land in Arizona and New Mexico from 1996 through 1998 during the fire season of May through September. The non-uniform and sporadic spatial nature of precipitation events in this region makes the use of rain gauge data a limited means of assessing when and where a cloud-to-ground lightning strike might have ignited a wildfire due to dry lightning. By analysing weather radar reflectivity data with lightning and wildfire data, characteristics of radar reflectivity can be used by fire weather forecasters to identify regions of increased ignition potential. Critical ranges of reflectivity, life span of a reflectivity cell, and storm movement are characteristics of radar reflectivity that are examined in this analysis. The results of this type of analysis can help focus attention of wildfire personnel to particular locations where there is known to be cloud-to-ground lightning in conjunction with radar reflectivity patterns that have been historically associated with wildfire ignition. Results from the analysis show that wildfire ignitions typically occur near the perimeter of a radar echo. The reflectivity values at the ignition location are less than the highest reflectivity located within the echo, and often magnitudes are sufficiently low to suggest that the precipitation is not reaching the ground in this dry region with high cloud bases. Interpretation of the duration, size and level of lightning activity of the radar echo associated with the ignition indicate that ignitions tend to occur in the early stages of a radar echo. However, there are often multiple storm cells having isolated areas of higher reflectivity within a radar echo at the time of ignition. Nearly two-thirds of radar echoes associated with wildfire ignitions moved more than 50 km throughout the echo’s lifetime. These moving storm systems often propagated in a northerly or easterly direction, and ignitions occurred on the leading edge of the storm in over half of the cases that propagated in the same direction. Forecasters can use results from this study to determine where there is an increased potential of wildfire ignitions when similar radar patterns appear in conjunction with lightning activity in the future.
Fire and stand history in two limber pine (Pinus flexilis) and Rocky Mountain bristlecone pine (Pinus aristata) stands in Colorado
Authors: Brown Peter M. , Schoettle Anna W.
Published: June 2008

We developed fire-scar and tree-recruitment chronologies from two stands dominated by limber pine and Rocky Mountain bristlecone pine in central and northern Colorado. Population structures in both sites exhibit reverse-J patterns common in uneven-aged forests. Bristlecone pine trees were older than any other at the site or in the limber pine stand, with the oldest tree dating to 780 AD and several dating to the 1000s and 1100s. The oldest trees in the limber pine stand date to the 1400s, with a majority of recruitment after an apparent bark beetle outbreak in the early 1800s. Spatial patterning in the limber pine suggests that the oldest trees established from seed caches left by corvid birds. Fire scars present in the early part of each chronology document that surface fire regimes dominated during certain periods. Decreased fire frequency, increased tree recruitment, and changes in species composition from the 1600s to1800s in the bristlecone pine may be reflective of cooler and wetter conditions during the Little Ice Age. Results suggest that a recent (1978) severe fire in the bristlecone pine stand that caused complete tree mortality was outside the historical range of variability in fire severity for at least the past ~1000 years.
Wildland fire probabilities estimated from weather model-deduced monthly mean fire danger indices
Authors: Preisler Haiganoush K. , Chen Shyh-Chin , Fujioka Francis , Benoit John W. , Westerling Anthony L.
Published: June 2008

The National Fire Danger Rating System indices deduced from a regional simulation weather model were used to estimate probabilities and numbers of large fire events on monthly and 1-degree grid scales. The weather model simulations and forecasts are ongoing experimental products from the Experimental Climate Prediction Center at the Scripps Institution of Oceanography. The monthly average Fosberg Fire Weather Index, deduced from the weather simulation, along with the monthly average Keetch–Byram Drought Index and Energy Release Component, were found to be more strongly associated with large fire events on a monthly scale than any of the other stand-alone fire weather or danger indices. These selected indices were used in the spatially explicit probability model to estimate the number of large fire events. Historic probabilities were also estimated using spatially smoothed historic frequencies of large fire events. It was shown that the probability model using four fire danger indices outperformed the historic model, an indication that these indices have some skill. Geographical maps of the estimated monthly wildland fire probabilities, developed using a combination of four indices, were produced for each year and were found to give reasonable matches to actual fire events. This method paves a feasible way to assess the skill of climate forecast outputs, from a dynamical meteorological model, in forecasting the probability of wildland fire severity with known precision.
A comparison of five sampling techniques to estimate surface fuel loading in montane forests
Authors: Sikkink Pamela G. , Keane Robert E.
Published: June 2008

Designing a fuel-sampling program that accurately and efficiently assesses fuel load at relevant spatial scales requires knowledge of each sample method’s strengths and weaknesses. We obtained loading values for six fuel components using five fuel load sampling techniques at five locations in western Montana, USA. The techniques included fixed-area plots, planar intersect, photoloads, a photoload macroplot, and a photo series. For each of the six fuels, we compared (1) the relative differences in load values among techniques and (2) the differences in load between each method and a reference sample. Totals from each method were rated for how much they deviated from totals for the reference in each fuel category. The planar-intersect method, which used 2.50 km of transects, was rated best overall for assessing the six fuels. Bootstrapping showed that at least 1.50 km of transect were needed to obtain estimates that approximate the reference sample. A newly developed photoload method, which compared fuel conditions on the forest floor with sets of pictures calibrated for load by fuel type, compared well with the reference and planar intersect. The commonly used photo series consistently produced higher mean load estimates than any other method for total fine woody debris (0.05–0.20 kg m–2) and logs (0.50–1.25 kg m–2).
Fire activity in Portugal and its relationship to weather and the Canadian Fire Weather Index System
Authors: Carvalho A. , Flannigan M. D. , Logan K. , Miranda A. I. , Borrego C.
Published: June 2008

The relationships among the weather, the Canadian Fire Weather Index (FWI) System components, the monthly area burned, and the number of fire occurrences from 1980 to 2004 were investigated in 11 Portuguese districts that represent respectively 66% and 61% of the total area burned and number of fires in Portugal. A statistical approach was used to estimate the monthly area burned and the monthly number of fires per district, using meteorological variables and FWI System components as predictors. The approach succeeded in explaining from 60.9 to 80.4% of the variance for area burned and between 47.9 and 77.0% of the variance for the number of fires; all regressions were highly significant (P < 0.0001). The monthly mean and the monthly maximum of daily maximum temperatures and the monthly mean and extremes (maximum and 90th percentile) of the daily FWI were selected for all districts, except for Bragança and Porto, in the forward stepwise regression for area burned. For all districts combined, the variance explained was 80.9 and 63.0% for area burned and number of fires, respectively. Our results point to highly significant relationships among forest fires in Portugal and the weather and the Canadian FWI System. The present analysis provides baseline information for predicting the area burned and number of fires under future climate scenarios and the subsequent impacts on air quality.
The relative importance of fine-scale fuel mosaics on reducing fire risk in south-west Tasmania, Australia
Authors: King Karen J. , Bradstock Ross A. , Cary Geoffrey J. , Chapman Joanne , Marsden-Smedley Jon B.
Published: June 2008

In many landscapes, an important fire management objective is to reduce the negative impacts from unplanned fires on people, property and ecological values. In Australia, there exists an inherent assumption that high spatial variability in fire ages and hence fuel loads will have negative effects on both the incidence and spread of subsequent fires, and will enhance ecological values. A recent study using the process-based computer simulation model FIRESCAPE-SWTAS predicted several relationships between prescribed burn treatment levels and spatial patterning and management objectives in south-west Tasmania, Australia. The present study extended this investigation to additionally explore the effects of prescribed burning treatment unit size on unplanned fire incidence and area burned both in the general landscape and specifically in fire-intolerant vegetation. Simulation results suggest that treatment level had the greatest influence on modifying fire effects, whereas treatment unit size had the least effect. The model predicted that all three parameters interacted to determine the mean annual area burnt by unplanned fires. In fire-intolerant vegetation, treatment unit size did not influence the incidence of unplanned fires and the area burnt by unplanned fires in these communities. Where significant differences were evident, fire risk was reduced by higher treatment levels, deterministic spatial patterns of burning units, and smaller burning unit sizes.
Implementation of mid-scale fire regime condition class mapping
Authors: Provencher Louis , Campbell Jeff , Nachlinger Jan
Published: June 2008

We used mid-scale Fire Regime Condition Class (FRCC) mapping to provide Hawthorne Army Depot in the Mount Grant area of Nevada, USA, with data layers to plan fuels restoration projects to meet resource management goals. FRCC mapping computes an index of the departure of existing conditions from the natural range of variability, and consists of five primary steps: (1) mapping the Potential Natural Vegetation Types (PNVT) based on interpretation of a soil survey; (2) refining PNVTs based on additional information; (3) modelling the natural range of variability (NRV) per PNVT; (4) using field verification, calculation and mapping of departure of current distribution of structural vegetation classes interpreted by remote sensing (IKONOS 4-m resolution satellite imagery) from the NRV; and (5) mapping structural vegetation classes that differ from reference conditions. Pinyon–juniper and mountain mahogany woodlands were found within the NRV, whereas departure increased from moderate for low and big sagebrush PNVTs and mixed desert shrub to high for riparian mountain meadow. Several PNVTs showed departures that were close to FRCC class limits. The common recommendation to reach the NRV was to decrease the percentage of late-development closed and cheatgrass-dominant classes, thus increasing the percentage of early and mid-development classes.
A Feminist Generation in Iran?
Authors: Kurzman Charles
Published: June 2008

Numerous observers have noted that a feminist generation of educated young women appears to be emerging in Iran, despite the anti-feminist discourse of the Iranian government. Evidence from three surveys conducted in 2000–2003 confirms and complicates these observations. Educated young women are significantly more likely to espouse feminist attitudes of various sorts than other Iranians, including educated young men. In addition, educated young women are significantly more likely to work outside the home, marry later, give birth later, have fewer children, and have more egalitarian marriages than other Iranian women. However, surprising proportions of older Iranians also espouse feminist attitudes, and a majority of respondents in one nationally representative sample of urban Iranians identify themselves as proponents of women's rights.
Issues and Paradoxes in the Development of Iranian National Cinema: An Overview
Authors: Poudeh Reza J. , Reza Shirvani M.
Published: June 2008

Contemporary Iranian cinema has enjoyed wide success on the international scene—winning awards at film festivals, receiving praise by critics, and being screened in many countries around the world. But this success has another side to it: at home in Iran, the movie theater attendance is in decline and a range of players, including individuals, policymakers and government entities continue to meddle in shaping its future. Throughout the twentieth century and during the two decades of post-revolutionary successes abroad, Iranian cinema developed its own unique style and aesthetic. A cinema which was sometimes nurtured and financially encouraged by the government, yet at other times censored or banned by it. This paper provides a brief survey of the history of Iranian cinema since the 1900s in order to reveal the paradoxical issues both propelling and bedeviling its development and the role of principal actors involved in fashioning an Iranian national cinema.
Tipping Point
Authors: Datong Li , Martinsen Joel
Published: June 2008

When Li Datong’s publication was closed down, the fallout marked a new era for Chinese journalism
Cat and Mouse
Authors: Xia Bill
Published: June 2008

Outwitting Internet censorship is a game of nerves. Bill Xia reports on his mission to find the cracks in the Great Firewall of China
Journey of a Red Heart
Authors: Gang Qian , Bandurski David
Published: June 2008

A Party rallying cry defines a generation’s coming of age, writes Qian Gang
Gay Capital
Authors: Ying Hong , Abrahamsen Eric
Published: June 2008

China’s homosexuals still have to lead an underground life, writes Hong Ying, and Beijing is the centre for an ongoing struggle for social acceptance
Altered Images
Authors: Young Nick
Published: June 2008

China’s rising unpopularity in the West is based on a distortion of a complex reality and may reinforce conservative trends back home, writes Nick Young
Strategies for Internet Reading with Different Reading Purposes: A Descriptive Study of Twelve Good Internet Readers
Authors: Zhang Shenglan , Duke Nell K.
Published: June 2008

This descriptive study explored different reading strategies 12 adult good Internet readers used while doing 3 Internet reading tasks, each with a different reading purpose: seeking specific information, acquiring general knowledge, and being entertained. This study investigated whether readers' strategies differed by reading purpose. Purposive selection was used in selecting adult, good, experienced Internet readers to participate in the study. The design of the study allowed for inclusion of additional participants if it was found that new reading strategies were still being identified by the 12th reader (they were not). Data were collected through navigational records and participants' stimulated recall following the three tasks about their reading process. More than 50 strategies were identified. Some strategies were used across purposes; others were not. In addition, readers adopted different patterns of reading strategies for different reading purposes. Results of the study suggest that it may be helpful to teach developing Internet readers to be aware of their purposes for Internet reading, and to use different Internet reading strategies because of their purpose for reading, though future research needs to be conducted to ascertain whether teaching these strategies really results in improved Internet reading skills. Results of the study also add to the research base regarding which Internet reading strategies may be worth teaching.
Methylmercury Induces Alveolar Macrophages Apoptosis
Authors: Kuo Tsun-Cheng
Published: June 2008

Through the use of a scanning electronic microscope, it was found that alveolar macrophages treated with 10 μM of methylmercury for 24 h showed a decrease of surface microvilli, and those treated with 15 μM of methylmercury underwent deformity and subsequent cell death. To investigate their death patterns, DNA was aspirated from alveolar macrophages and analyzed by electrophoresis. It was discovered that the DNA ladder phenomenon became more obvious as the methylmercury increased in concentration. When 5 mM EGTA was used to eliminate calcium ions, a decrease of the ladder phenomenon was observed. Zinc at 1 mM had a similar inhibitory effect. Moreover, an apoptosis peak was observed on flow cytometry analysis of DNA stained with propidium iodide. Alveolar macrophages stained with Hoechst 33342 demonstrated apoptotic bodies induced by methylmercury. The above data indicate that methylmercury can induce a typical apoptosis in alveolar macrophages. Continuing onto the study of the mechanism of apoptosis as induced by methylmercury in alveolar macrophages, it was discovered that methylmercury could increase the intracellular calcium ion concentration and decrease the pH in alveolar macrophages. To find out which endonuclease was responsible for the methylmercury-induced DNA fragmentation of alveolar macrophages, the nuclear proteins of alveolar macrophages was aspirated and tested under different pH values and in conditions with or without calcium ions, and it was discovered that the endonuclease was calcium dependent without relations to pH values.
Microarray Evaluation of the Listeria monocytogenes Infection and Amoxicillin Treatment in Mice
Authors: Dieterich Christine , Iglehart Dawn , Riccio Edward , Mirsalis Jon C. , Ng Hanna H.
Published: June 2008

By using Affymetrix Mouse Genome Arrays and 20 biological replicates per experimental condition, the predictive value of liver and blood gene expression profiles previously identified was validated as predictive of Listeria monocytogenes infection severity (lethal and nonlethal infection). The ability of these genes to predict the outcome of antibiotic treatment was also assessed. Lethally infected BALB/c mice were treated with amoxicillin at 10 or 20 mg/kg; only the higher dose prevented death. The liver genes predicted that 70% of the animals treated at 10 mg/kg, but only 25% of the mice treated at 20 mg/kg, belonged to the lethal infection group, and this prediction was similar to the ultimate mortality outcome. These results confirm the value of microarrays as tools to predict host response to infection and efficacy of antibacterial therapy. These results might lead to applications that would help clinicians to adjust antibiotic dosages for efficient treatment but yet without toxicity.
Effects of Quillaja Saponin (Quillaja saponaria) on Early Embryonic Zebrafish (Danio rerio) Development
Authors: Hassan Sherif M. , Moussa Eid. A. , Abbott Louise C.
Published: June 2008

Although much attention has focused on environmental contamination by heavy metals, pesticides, and polychlorinated biphenyls, potential deleterious effects of naturally occurring organic compounds have received much less consideration. Saponins, which are glycosides found in many plants, are important, environmentally ubiquitous organic compounds. Saponins have both beneficial and deleterious effects in adults, but little is known about how saponins effect early vertebrate embryonic development. The authors tested the toxicity of quillaja saponin using a zebrafish embryo assay. Quillaja saponin, extracted from bark of the tree, Quillaja saponaria, is a common foaming agent used in foods and beverages. At 6 h post fertilization, zebrafish embryos were exposed to five concentrations (0 [negative control], 1, 5, 10 or 20 μg) of quillaja saponin per milliliter of medium. Zebrafish embryos exposed to 2% ethanol were positive controls (100% embryonic death). Embryos were assessed at 30, 54, and 72 h post fertilization for changes in embryonic development, mortality, time of hatching, and morphological deformities. Embryos exposed to 1 and 5 μg saponin were healthy, showed no obvious deformities, but exhibited shrinkage of the chorion. Hatching time for zebrafish embryos exposed to 1 and 5 μg/ml saponin decreased by 18 h compared to unexposed embryos. Zebrafish embryos treated with 5 μg/ml saponin responded less to touch than embryos treated with 1 μg/ml saponin or controls. Zebrafish embryos exposed to more than 5 μg/ml saponin exhibited 100% embryonic mortality. These results indicate that exposure to 5 μg/ml or less of quillaja saponin acts as a growth promoter, whereas concentrations of 10 μg/ml or greater are lethal.
Mechanism and Treatment of Sulfide-Induced Coma: A Rat Model
Authors: Almeida A. F. , Nation P. N. , Guidotti T. L.
Published: June 2008

Sodium hydrosulfide and dimethylsulfide duplicate the effects of hydrogen sulfide in causing coma in Sprague-Dawley rats and are additive for lethality. Nitrite, pyruvate and dithiothreitol had no significant effect on coma or lethality but bicarbonate with and without glucose reduced duration of coma. This finding suggests an antidotal treatment.
ESecRout: An Energy Efficient Secure Routing for Sensor Networks
Authors: Yin Jian , Madria Sanjay K.
Published: June 2008

In this paper, we present an Energy Efficient Secure Routing Protocol for Sensor Networks ( ESecRout). The protocol uses the symmetric cryptography to secure messages, and uses a small cache in sensor nodes to record the partial routing path (previous and next nodes) to the destination. It guarantees that the destination will be able to identify and discard the tampered messages and ensure that the messages received are not tampered with. Simulation shows ESecRout's performance comparison with the non-secure routing protocol AODV [ 1 ] and the secure routing protocol SAODV [ 2 ]. Our protocol needs a little more route discovery overhead (about 8%) and costs a little more energy (about 8%) than AODV, but it performs much better than SAODV which needs much more route discovery overhead (about 33%) and costs much more energy (35%) than AODV. Simulation results also show that the packet delivery ratio and packet latency of AODV, SAODV, and ESecRout are almost the same. Thus, we show that our protocol ESecRout provides energy efficient secure routing.
Analysis of Cluster Interconnection Schemes in 802.15.4 Beacon Enabled Networks
Authors: Mišić Jelena , Udayshankar Ranjith
Published: June 2008

In this paper, we consider the interconnection of IEEE 802.15.4 beacon enabled network clusters. We discuss two types of interconnections. One type can be achieved by using the PAN coordinator node as the bridging device and the other type is achieved by using ordinary network nodes as bridge nodes. We discuss design and performance issues of both kinds of interconnections.