bluuebunny/crossref_metadata_2025 huggingface dataset:
Time‐varying parametric subharmonic instability from repeat CTD surveys in the northwestern Pacific Ocean
Authors: Qiu Bo , Chen Shuiming , Carter Glenn S.
Published: August 2012

Time‐varying diapycnal diffusivity signals are estimated using the fine‐scale parameterization method from high‐resolution CTD data along three repeat sections in the northwestern Pacific Ocean. Indicative of the parametric subharmonic instability (PSI), locally‐elevated diapycnal mixing is detected alongallthree sections within the 25°–29°N band where bottom topography is relatively featureless. Due to their proximity to the semidiurnal internal tide generation sites, the two sections along ∼137°E have a time‐mean diffusivity value 2.5 × 10−5 m2 s−1 in the 300–2,000 m upper ocean. In contrast, it is 1.2 × 10−5 m2 s−1along the 165°E section. The time‐varying diffusivity along both sections is dominated by signals whose vertical structure resembles the local first dynamic normal mode profile. At the 137°E site of 25°–29°N, the local spring‐neap modulated semidiurnal tidal current is found to lead the CTD‐derived diffusivity time series by 6 days and can alter the diffusivity level by 0.24 × 10−5 m2 s−1. Similarly, the concurrent surface wind work is found to modify the diffusivity level by 0.35 × 10−5 m2 s−1. The combined spring‐neap tide and wind work forcing explains 47% of the observed, time‐varying diffusivity signals.
Sea surface pCO2 cycles and CO2 fluxes at landfast sea ice edges in Amundsen Gulf, Canada
Authors: Else B. G. T. , Galley R. J. , Papakyriakou T. N. , Miller L. A. , Mucci A. , Barber D.
Published: August 2012

In late fall, spring, and early summer, we measured the surface ocean and atmospheric partial pressures of CO2 (pCO2sw and pCO2atm, respectively) to calculate CO2 gradients (ΔpCO2 = pCO2sw − pCO2atm) and resulting fluxes along the landfast ice regions of southern Amundsen Gulf, Canada. In both the fall and spring seasons we observed positive ΔpCO2caused by wind‐driven upwelling. The presence of a landfast ice edge appeared to be an important factor in promoting this upwelling in some instances. Despite the potential for significant CO2 evasion, we calculated small fluxes during these periods due to high sea ice concentration. In summer, ΔpCO2 became strongly negative across the entire study area. Primary production no doubt played a role in the pCO2swdrawdown, but we found evidence that sea ice melt and dissolution of ice‐bound calcium carbonate crystals may also have been contributing factors. The seasonal ΔpCO2 cycle suggests a net annual sink of atmospheric CO2 for these landfast ice regions, since calculated summer uptake by the ocean was much stronger than fall/spring outgassing and occurred over a longer time period. However, we hypothesize that this balance is highly dependent on the strength of upwelling and the timing of ice formation and decay, and therefore may be influenced by interannual variability and the effects of climate change.
Coupled Model Intercomparison Project 5 (CMIP5) simulations of climate following volcanic eruptions
Authors: Driscoll Simon , Bozzo Alessio , Gray Lesley J. , Robock Alan , Stenchikov Georgiy
Published: August 2012

The ability of the climate models submitted to the Coupled Model Intercomparison Project 5 (CMIP5) database to simulate the Northern Hemisphere winter climate following a large tropical volcanic eruption is assessed. When sulfate aerosols are produced by volcanic injections into the tropical stratosphere and spread by the stratospheric circulation, it not only causes globally averaged tropospheric cooling but also a localized heating in the lower stratosphere, which can cause major dynamical feedbacks. Observations show a lower stratospheric and surface response during the following one or two Northern Hemisphere (NH) winters, that resembles the positive phase of the North Atlantic Oscillation (NAO). Simulations from 13 CMIP5 models that represent tropical eruptions in the 19th and 20th century are examined, focusing on the large‐scale regional impacts associated with the large‐scale circulation during the NH winter season. The models generally fail to capture the NH dynamical response following eruptions. They do not sufficiently simulate the observed post‐volcanic strengthened NH polar vortex, positive NAO, or NH Eurasian warming pattern, and they tend to overestimate the cooling in the tropical troposphere. The findings are confirmed by a superposed epoch analysis of the NAO index for each model. The study confirms previous similar evaluations and raises concern for the ability of current climate models to simulate the response of a major mode of global circulation variability to external forcings. This is also of concern for the accuracy of geoengineering modeling studies that assess the atmospheric response to stratosphere‐injected particles.
Modeling sub‐sea permafrost in the East Siberian Arctic Shelf: The Laptev Sea region
Authors: Nicolsky D. J. , Romanovsky V. E. , Romanovskii N. N. , Kholodov A. L. , Shakhova N. E. , Semiletov I. P.
Published: August 2012

Models of sub‐sea permafrost evolution vary significantly in employed physical assumptions regarding the paleo‐geographic scenario, geological structure, thermal properties, initial temperature distribution, and geothermal heat flux. This work aims to review the underlying assumptions of these models as well as to incorporate recent findings, and hence develop an up‐to‐date model of the sub‐sea permafrost dynamics at the Laptev Sea shelf. In particular, the sub‐sea permafrost model developed here incorporates thermokarst and land‐ocean interaction theory, and shows that the sediment salinity and a temperature‐based parametrization of the unfrozen water content are critical factors influencing sub‐sea permafrost dynamics. From the numerical calculations, we suggest development of open taliks may occur beneath submerged thaw lakes within a large area of the shelf.
Rapid development of anisotropic ice‐crystal‐alignment fabrics inferred from englacial radar polarimetry, central West Antarctica
Authors: Matsuoka Kenichi , Power Donovan , Fujita Shuji , Raymond Charles F.
Published: August 2012

Anisotropy in englacial radar power was measured using 60‐MHz and 179‐MHz copolarized pulse‐modulated radar at 19 sites in central West Antarctica. The study region is a 100 × 300 km2area near the West Antarctic Ice Sheet Divide that separates ice flow toward the Ross and Amundsen Embayments. The frequency dependence of the returned power indicates that most of the radar data are affected by vertical variations in the crystal‐orientation fabric (COF), though the 60‐MHz data are more affected by acidity contrasts in the top 1000 m. Significant polarimetric variations occur at most sites, likely due to effects of the anisotropic COF patterns. More anisotropic variations occur at sites with significant horizontal strain, whereas more isotropic variations occur at sites where vertical compression dominates. Azimuthal shifts with depth of the principal axes of COF were found in shallow ice near the current flow divide and at greater depths over locations of rough bed. The former indicates that the divide has differentially migrated, resulting in a rotation of the principal COF axes. Nevertheless, the regionally consistent radar signatures suggest that the first‐order ice properties in this area have remained constant and that no major changes in the strain configuration or ice topography have occurred for the past five to eight thousand years. We conclude that shallow polarimetric features can be related to the current strain configurations, and that englacial polarimetric features can help constrain current ice rheology and evolution of the ice topography.
Global Mental Health: A Resource Primer for Exploring the Domain
Authors: O'Donnell Kelly S.
Published: August 2012

Global mental health (GMH) is a burgeoning domain of research, advocacy, and practice. Its daunting challenge is reflected in the expectation that one in four humans will experience a serious mental, neurological, or substance abuse condition in their lifetime. The world's poor are especially burdened, having the least access to care and plagued by social stigma and discrimination. In solidarity with the emerging GMH movement, which focuses on improving wellbeing and mental health equity, this article identifies core GMH resources to further orient those with various levels of experience in the mental health, psychology, and health fields. Six “resource areas” are explored with an emphasis on the last two decades: organizations, publications, conferences, training, human rights, and the humanitarian sector. The overall article is presented as a “resource primer” to promote and guide the integration of mental health into our personal and global agendas for human wellbeing. Colleagues are encouraged to use this primer in training settings, build on it with additional materials from international sources, and expand it to include additional resource areas.
Significant and persistent impact of timber harvesting on soil microbial communities in Northern coniferous forests
Authors: Hartmann Martin , Howes Charles G , VanInsberghe David , Yu Hang , Bachar Dipankar , Christen Richard , Henrik Nilsson Rolf , Hallam Steven J , Mohn William W
Published: August 2012

Forest ecosystems have integral roles in climate stability, biodiversity and economic development. Soil stewardship is essential for sustainable forest management. Organic matter (OM) removal and soil compaction are key disturbances associated with forest harvesting, but their impacts on forest ecosystems are not well understood. Because microbiological processes regulate soil ecology and biogeochemistry, microbial community structure might serve as indicator of forest ecosystem status, revealing changes in nutrient and energy flow patterns before they have irreversible effects on long-term soil productivity. We applied massively parallel pyrosequencing of over 4.6 million ribosomal marker sequences to assess the impact of OM removal and soil compaction on bacterial and fungal communities in a field experiment replicated at six forest sites in British Columbia, Canada. More than a decade after harvesting, diversity and structure of soil bacterial and fungal communities remained significantly altered by harvesting disturbances, with individual taxonomic groups responding differentially to varied levels of the disturbances. Plant symbionts, like ectomycorrhizal fungi, and saprobic taxa, such as ascomycetes and actinomycetes, were among the most sensitive to harvesting disturbances. Given their significant ecological roles in forest development, the fate of these taxa might be critical for sustainability of forest ecosystems. Although abundant bacterial populations were ubiquitous, abundant fungal populations often revealed a patchy distribution, consistent with their higher sensitivity to the examined soil disturbances. These results establish a comprehensive inventory of bacterial and fungal community composition in northern coniferous forests and demonstrate the long-term response of their structure to key disturbances associated with forest harvesting.
Influence of Diet on Visceral Adipose Remodeling in NONcNZO10 Mice With Polygenic Susceptibility for Type 2 Diabetes
Authors: Adi Nikhil C. , Adi Jennipher N. , Cesar Liliana , Agatston Arthur S. , Kurlansky Paul , Webster Keith A.
Published: August 2012

Visceral adipose tissue (VAT) is a source of inflammatory cytokines that in obese subjects may contribute to low‐level systemic inflammation and development of metabolic syndrome. Expansion of VAT involves adipocyte hyperplasia and hypertrophy and requires breakdown of the extracellular matrix and increased vascular outgrowth. To investigate changes of gene expression associated with VAT expansion and the role of combined genetics and diet, we implemented gene microarray analyses of VAT in NONcNZO10 (NZ10) and control SWR/J mice subjected to control chow (CD) or a diet of high protein and fish oil (HPO). NZ10 mice on CD showed increased body weight, hyperglycemia, and hyperinsulinemia at 25 weeks whereas those on HPO diet retained normal insulin levels and were normoglycemic. Two‐way ANOVA revealed a significant interaction between diet and strain on blood glucose, serum insulin, and percent fat but not for body weight. Microarray heat maps revealed a remarkable combined effect of genetics and diet on genes that regulate extracellular matrix as well as angiogenic genes. Real time‐PCR (RT‐PCR) confirmed markedly increased expression of matrix metalloproteinases (MMPs) 2, 3, 11, and 12, vascular endothelial growth factor‐A and C (VEGF‐A and C), Von Willebrand Factor, and peroxisome proliferator‐activated receptor‐γ (PPAR‐γ) selectively in the NZ10/CD group. MMP7 was significantly decreased. Protein levels of MMP2, 3, and 9 were significantly increased in the VA of NZ10 mice fed CD while those of MMP7 were downregulated. Microarrays also revealed diet‐dependent two to fourfold increased expression of all four tissue inhibitor of metalloproteinases (TIMP) isoforms in NZ10 mice. Two‐way ANOVA confirmed strongly interactive roles of diet and genetics on fat deposition and progression of type 2 diabetes in this polygenic mouse model.
Exact Green's function of the reversible diffusion-influenced reaction for an isolated pair in two dimensions
Authors: Prüstel Thorsten , Meier-Schellersheim Martin
Published: August 2012

We derive an exact Green's function of the diffusion equation for a pair of disk-shaped interacting particles in two dimensions subject to a backreaction boundary condition. Furthermore, we use the obtained function to calculate exact expressions for the survival probability and the time-dependent rate coefficient for the initially unbound pair and the survival probability of the bound state. The derived expressions will be of particular utility for the description of reversible membrane-bound reactions in cell biology.
Decay of C60 by delayed ionization and C2 emission: Experiment and statistical modeling of kinetic energy release
Authors: Lebeault M.-A. , Baguenard B. , Concina B. , Calvo F. , Climen B. , Lépine F. , Bordas C.
Published: August 2012

C60 molecules highly excited in the nanosecond regime decay following ionization and dissociation by emitting a series of carbon dimers, as well as other small fragments if excitation is strong enough. The fragmentation mass spectrum and kinetic energy release of all charged fragments obtained in these experiments are interpreted within the framework of the Weisskopf theory, using a realistic Monte Carlo procedure in which the rates of all relevant decay channels are modeled using Arrhenius expressions. Comparison between the measurements and the simulated spectra allows the distribution of deposited energy to be accurately estimated. The dependence of the fragment kinetic energies on the laser fluence, found in the simulation but not observed in the experimental results, indicates that the small fragments are not necessarily emitted from small fullerenes resulting from C60 by sequential decay. Rather, direct multifragmentation of C60 is invoked to interpret the observed patterns. The possible role of post-ionization of neutral emitted fragments is discussed.
Sound velocity measurements by x-ray shadowgraph technique for melting phenomena at ultrahigh-pressure regime
Authors: Shigemori K. , Sakaiya T. , Asakura Y. , Kondo T. , Shimizu K. , Kadono T. , Hironaka Y. , Azechi H.
Published: August 2012

Developments in measuring sound velocity of matter under ultrahigh pressure are described. We employed a time-resolved x-ray shadowgraph technique to measure the sound velocity of shock-compressed diamond and iron foils at around melt. The sound velocity significantly dropped at melting, a behavior that has been difficult to clarify by conventional measurements by subtracting particle velocity from shock velocity (us – up). In addition to sound velocity, other important parameters were also obtained simultaneously.
Generation and diagnostics of atmospheric pressure CO2 plasma by laser driven plasma wind tunnel
Authors: Matsui Makoto , Tanaka Kensaku , Nomura Satoshi , Komurasaki Kimiya , Yamagiwa Yoshiki , Arakawa Yoshihiro
Published: August 2012

Atmospheric pressure CO2 plasma was generated by a laser driven plasma wind tunnel. At an ambient pressure of 0.38 MPa, a stable plasma was maintained by a laser power of 1000 W for more than 20 min. The translational temperature was measured using laser absorption spectroscopy with the atomic oxygen line at 777.19 nm. The measured absorption profiles were analyzed by a Voigt function considering Doppler, Stark, and pressure-broadening effects. Under the assumption of thermochemical equilibrium, all broadening effects were consistent with each other. The measured temperature ranged from 8500 K to 8900 K.
How often does the Unruh-DeWitt detector click beyond four dimensions?
Authors: Hodgkinson Lee , Louko Jorma
Published: August 2012

We analyse the response of an arbitrarily accelerated Unruh-DeWitt detector coupled to a massless scalar field in Minkowski spacetimes of dimensions up to six, working within first-order perturbation theory and assuming a smooth switch-on and switch-off. We express the total transition probability as a manifestly finite and regulator-free integral formula. In the sharp switching limit, the transition probability diverges in dimensions greater than three but the transition rate remains finite up to dimension five. In dimension six, the transition rate remains finite in the sharp switching limit for trajectories of constant scalar proper acceleration, including all stationary trajectories, but it diverges for generic trajectories. The divergence of the transition rate in six dimensions suggests that global embedding spacetime methods for investigating detector response in curved spacetime may have limited validity for generic trajectories when the embedding spacetime has dimension higher than five.
Reduced graphene oxide produced by rapid-heating reduction and its use in carbon-based field-effect transistors
Authors: Lee In-yeal , Wang Jianwei , Kim Gil-Ho , Park Jin-Hong , Kannan E. S. , Jang Ji-Hoon , Kwon Young-Uk
Published: August 2012

Highly conductive and water-dispersible sheets of reduced graphene oxide (RGO) were produced by rapidly heating graphene oxide (GO) paper at a low temperature (300 °C) for a short processing time of 3 s. The GO paper was thermally treated during the rapid-heating reduction process and, consequently, the oxygen functional groups in the obtained RGO were highly reduced. The RGO film displays good thermal stability, crystallinity, low sheet resistance, and good dispersibility in water, which makes it an ideal candidate to be used in various carbon-based electronic devices. We finally demonstrate the suitability of RGO as an active channel material and as a source-drain electrode for graphene field-effect transistors, which bring the possibility of realizing all-carbon devices a step closer to reality.
The ultraviolet spectrum of OCS from first principles: Electronic transitions, vibrational structure and temperature dependence
Authors: Schmidt J. A. , Johnson M. S. , McBane G. C. , Schinke R.
Published: August 2012

Global three dimensional potential energy surfaces and transition dipole moment functions are calculated for the lowest singlet and triplet states of carbonyl sulfide at the multireference configuration interaction level of theory. The first ultraviolet absorption band is then studied by means of quantum mechanical wave packet propagation. Excitation of the repulsive 2 1A′ state gives the main contribution to the cross section. Excitation of the repulsive 1 1A″ state is about a factor of 20 weaker at the absorption peak (Eph ≈ 45 000 cm−1) but becomes comparable to the 2 1A′ state absorption with decreasing energy (35 000 cm−1) and eventually exceeds it. Direct excitation of the repulsive triplet states is negligible except at photon energies Eph < 38 000 cm−1. The main structure observed in the cross section is caused by excitation of the bound 2 3A″ state, which is nearly degenerate with the 2 1A′ state in the Franck-Condon region. The structure observed in the low energy tail of the spectrum is caused by excitation of quasi-bound bending vibrational states of the 2 1A′ and 1 1A″ electronic states. The absorption cross sections agree well with experimental data and the temperature dependence of the cross section is well reproduced.
Transmission through stacked 2D periodic distributions of square conducting patches
Authors: Kaipa Chandra S. R. , Yakovlev Alexander B. , Medina Francisco , Mesa Francisco
Published: August 2012

In this paper, we study the transmissivity of electromagnetic waves through stacked two-dimensional printed periodic arrays of square conducting patches. An analytical circuit-like model is used for the analysis. The model accounts for the details of the transmission spectrum provided that the period of the unit cell of each patterned layer is well below the wavelength in the dielectric slabs separating the printed surfaces. In particular, we analyze the low-pass band and rejection band behavior of the multilayer structure, and the results are validated by comparison with a computationally intensive finite element commercial electromagnetic solver. The limiting case of an infinite periodic structure is analytically solved and the corresponding band structure is used to explain the passband/stopband behavior of finite structures. In addition, we study in depth the elementary unit cell consisting of a single dielectric slab coated by two metal patch arrays, and its resonance behavior is explained in terms of Fabry-Pérot resonances when the electrical thickness of the slab is large enough. In such case, the concept of equivalent thickness of the equivalent ideal Fabry-Pérot resonator is introduced. For electrically thinner slabs it is also shown that the analytical model is still valid, and its corresponding first transmission peak is explained in terms of a lumped-circuit LC resonance.
Computation of the spectrum of spatial Lyapunov exponents for the spatially extended beam-plasma systems and electron-wave devices
Authors: Hramov Alexander E. , Koronovskii Alexey A. , Maximenko Vladimir A. , Moskalenko Olga I.
Published: August 2012

The spectrum of Lyapunov exponents is powerful tool for the analysis of the complex system dynamics. In the general framework of nonlinear dynamics, a number of the numerical techniques have been developed to obtain the spectrum of Lyapunov exponents for the complex temporal behavior of the systems with a few degree of freedom. Unfortunately, these methods cannot be applied directly to analysis of complex spatio-temporal dynamics of plasma devices which are characterized by the infinite phase space, since they are the spatially extended active media. In the present paper, we propose the method for the calculation of the spectrum of the spatial Lyapunov exponents (SLEs) for the spatially extended beam-plasma systems. The calculation technique is applied to the analysis of chaotic spatio-temporal oscillations in three different beam-plasma model: (1) simple plasma Pierce diode, (2) coupled Pierce diodes, and (3) electron-wave system with backward electromagnetic wave. We find an excellent agreement between the system dynamics and the behavior of the spectrum of the spatial Lyapunov exponents. Along with the proposed method, the possible problems of SLEs calculation are also discussed. It is shown that for the wide class of the spatially extended systems, the set of quantities included in the system state for SLEs calculation can be reduced using the appropriate feature of the plasma systems.
Plasma stabilisation of metallic nanoparticles on silicon for the growth of carbon nanotubes
Authors: Esconjauregui S. , Cepek C. , Fouquet M. , Bayer B. C. , Gamalski A. D. , Chen Bingan , Xie Rongsi , Bhardwaj S. , Ducati C. , Hofmann S. , Robertson J.
Published: August 2012

Ammonia (NH3) plasma pretreatment is used to form and temporarily reduce the mobility of Ni, Co, or Fe nanoparticles on boron-doped mono- and poly-crystalline silicon. X-ray photoemission spectroscopy proves that NH3 plasma nitrides the Si supports during nanoparticle formation which prevents excessive nanoparticle sintering/diffusion into the bulk of Si during carbon nanotube growth by chemical vapour deposition. The nitridation of Si thus leads to nanotube vertical alignment and the growth of nanotube forests by root growth mechanism.
Nickel vacancy behavior in the electrical conductance of nonstoichiometric nickel oxide film
Authors: Soo Kim Dong , Chul Lee Hee
Published: August 2012

Nickel vacancy behavior in electrical conductance is systematically investigated using various analysis methods on nickel oxide films deposited at different oxygen partial pressures. The results of Rutherford backscattering, x-ray diffraction, and Auger electron spectroscopy analyses demonstrate that the sputtered nickel oxide films are nickel-deficient. Through the deconvolution of Ni2p and O1s spectra in the x-ray photoelectron spectroscopy data, the number of Ni3+ ions is found to increase with the O2 ratio during the deposition. According to the vacancy model, nickel vacancies created from the non-stoichiometry are concluded to produce Ni3+ ions which lead to an increment of the conductivity of the nickel oxide films due to the increase of the hole concentration.
Oscillating plasma bubbles. II. Pulsed experiments
Authors: Stenzel R. L. , Urrutia J. M.
Published: August 2012

Time-dependent phenomena have been investigated in plasma bubbles which are created by inserting spherical grids into an ambient plasma and letting electrons and ions form a plasma of different parameters than the ambient one. There are no plasma sources inside the bubble. The grid bias controls the particle flux. There are sheaths on both sides of the grid, each of which passes particle flows in both directions. The inner sheath or plasma potential develops self consistently to establish charge neutrality and divergence free charge and mass flows. When the electron supply is restricted, the inner sheath exhibits oscillations near the ion plasma frequency. When all electrons are excluded, a virtual anode forms on the inside sheath, reflects all ions such that the bubble is empty. By pulsing the ambient plasma, the lifetime of the bubble plasma has been measured. In an afterglow, plasma electrons are trapped inside the bubble and the bubble decays as slow as the ambient plasma. Pulsing the grid voltage yields the time scale for filling and emptying the bubble. Probes have been shown to modify the plasma potential. Using pulsed probes, transient ringing on the time scale of ion transit times through the bubble has been observed. The start of sheath oscillations has been investigated. The instability mechanism has been qualitatively explained. The dependence of the oscillation frequency on electrons in the sheath has been clarified.
Oscillating plasma bubbles. III. Internal electron sources and sinks
Authors: Stenzel R. L. , Urrutia J. M.
Published: August 2012

An internal electron source has been used to neutralize ions injected from an ambient plasma into a spherical grid. The resultant plasma is termed a plasma “bubble.” When the electron supply from the filament is reduced, the sheath inside the bubble becomes unstable. The plasma potential of the bubble oscillates near but below the ion plasma frequency. Different modes of oscillations have been observed as well as a subharmonic and multiple harmonics. The frequency increases with ion density and decreases with electron density. The peak amplitude occurs for an optimum current and the instability is quenched at large electron densities. The frequency also increases if Langmuir probes inside the bubble draw electrons. Allowing electrons from the ambient plasma to enter, the bubble changes the frequency dependence on grid voltage. It is concluded that the net space charge density in the sheath determines the oscillation frequency. It is suggested that the sheath instability is caused by ion inertia in an oscillating sheath electric field which is created by ion bunching.
Costs for polar-orbiting weather satellites climb again
Authors: Kramer David
Published: August 2012

Delay in launch of spacecraft is expected to cause deteriorated forecasts.
Cold Plasma Metallization of Supported Metal Salt Layers
Authors: Crowther J. M. , Badyal J. P. S.
Published: August 2012

Non-isothermal H2 plasma reduction of supported silver nitrate or palladium acetate leads to the formation of metallic films. This method benefits from being able to coat heat-sensitive substrates, as well as complex shaped objects, without the requirement for large amounts of solvent or complex chemical synthesis. X-ray diffraction, X-ray photoelectron spectroscopy, attenuated total reflectance-FTIR spectroscopy, and optical microscopy have been used to follow the various stages of this low temperature metallization technique.
Four AUXIN RESPONSE FACTOR genes downregulated by microRNA167 are associated with growth and development in Oryza sativa
Authors: Liu Hai , Jia Shenghua , Shen Defeng , Liu Jin , Li Jie , Zhao Heping , Han Shengcheng , Wang Yingdian
Published: August 2012

MicroRNA167 (miR167), as a conserved miRNA, has been implicated in auxin signalling by regulating the expression of certain auxin response factor (ARF) genes to determine the plant developmental process. Among the 10 MIR167 genes of rice, the precursor structures derived from MIR167a, MIR167b and MIR167c produce miR167 with high efficiency. To explore the biological function of miR167 in rice, four of its predicted target genes, OsARF6, OsARF12, OsARF17 and OsARF25, were identified in vivo. Although the expression levels of miR167 and its target OsARFs did not show an obvious negative correlation, the enhanced miR167 level in transgenic rice overexpressing miR167 resulted in a substantial decrease in mRNA levels of the four OsARF genes. Moreover, the transgenic rice plants were small in stature with remarkably reduced tiller number. These results suggest that miR167 is important for the appropriate expression of at least four OsARFs, which mediate the auxin response, to contribute to the normal growth and development of rice.
Validating the Malheur model for predicting ponderosa pine post-fire mortality using 24 fires in the Pacific Northwest, USA
Authors: Thies Walter G. , Westlind Douglas J.
Published: August 2012

Fires, whether intentionally or accidentally set, commonly occur in western interior forests of the US. Following fire, managers need the ability to predict mortality of individual trees based on easily observed characteristics. Previously, a two-factor model using crown scorch and bole scorch proportions was developed with data from 3415 trees for predicting the probability of ponderosa pine (Pinus ponderosa Dougl. ex Laws.) mortality following prescribed fire. Here, we report validation of that model for broader application using data from 10 109 ponderosa pines in 17 prescribed fires and 7 wildfires, observed for 3 years post-fire, from east of the Cascade Range crest in Washington, Oregon and northern California. The overall rate of correct classification was 87.1% and the rate of correctly predicting mortality was 80.1%. Similar accuracy is reported when testing the model for small trees (<53.3-cm diameter at breast height), wildfire, prescribed fire, and when using a field guide that simplifies application of the model. For large trees (≥53.3-cm diameter at breast height), the overall rate of correct prediction was 93.6% and the rate of correctly predicting mortality was 65.2%. These results suggest the Malheur model is useful for predicting ponderosa pine mortality following fires in this region.
Proximity to grasslands influences fire frequency and sensitivity to climate variability in ponderosa pine forests of the Colorado Front Range
Authors: Gartner Meredith H. , Veblen Thomas T. , Sherriff Rosemary L. , Schoennagel Tania L.
Published: August 2012

This study examines the influence of grasslands on fire frequency and occurrence in the ponderosa pine (Pinus ponderosa)-dominated forests of the central and northern Colorado Front Range. Fire frequency based on tree-ring fire-scar data was compared between 34 fire history sites adjacent to grasslands and 34 fire history sites not adjacent to grasslands for the time period 1675–1920. Relationships were examined between fire occurrence and values of the Palmer Drought Severity Index and sea-surface temperatures from the NINO3 region of the tropical Pacific Ocean (positive values indicating El Niño-like conditions and negative values La Niña-like conditions). Ponderosa pine stands adjacent to grasslands experienced more frequent fire than stands not adjacent to grasslands (P < 0.05) owing to proximity to prevalent fine fuels able to support relatively frequent surface fires. Fire activity adjacent to grasslands showed a lagged positive relationship with moist years (positive Palmer Drought Severity Index and positive NINO3) antecedent to fire events whereas fire occurrence at sites not adjacent to grasslands showed no relationship to antecedent moist years. This study illustrates how the presence of grasslands in a ponderosa pine landscape results in increased fire frequency (a bottom–up influence) and also increases the sensitivity of fire activity to interannual climate variability (a top–down influence).
Characteristics of lightning-attributed wildland fires in south-east Australia
Authors: Dowdy Andrew J. , Mills Graham A.
Published: August 2012

Wildland fires attributed to lightning ignitions in Victoria, Australia, are examined systematically through the use of lightning occurrence data. Lightning stroke data were obtained by a network of ground-based lightning detection sensors over a 9-year period. Characteristics of these fires are examined including the temporal variability in the average chance of fire occurrence per lightning stroke and the time period from lightning ignition of a fire until the fire grows large enough to be first observed, as well as distributions of fire duration and total area burnt. It is found that the time of day that lightning occurs does not have a significant influence on the chance of fire per lightning stroke, in contrast to the time of year, for which a significant annual variation occurs. Regional variability is examined by discussing the results for Victoria, Australia, in relation to results of studies from other parts of the world.
Properties affecting the consumption of sound and rotten coarse woody debris in northern Idaho: a preliminary investigation using laboratory fires
Authors: Hyde Joshua C. , Smith Alistair M. S. , Ottmar Roger D.
Published: August 2012

This study evaluates the consumption of coarse woody debris in various states of decay. Samples from a northern Idaho mixed-conifer forest were classified using three different classification methods, ignited with two different ignition methods and consumption was recorded. Intrinsic properties that change with decay were measured including carbon to nitrogen ratio, density, heat content, lignin content, moisture content and surface area-to-volume ratio. Consumption for logs in different stages of decay is reported with characterisation of wood properties. Results indicate very decayed coarse woody debris is likely to be consumed to a substantially greater degree than sound coarse woody debris given similar conditions. High consumption occurred in debris with low-density, high-lignin content and high gravimetric heat content; however, lignin content and density showed the highest correlation with consumption. The Maser classification method grouped very rotten logs with high consumption into decay class 4 and the remainder into class 3. Trends in consumption were similar regardless of ignition; however low-intensity long-duration ignition produced higher consumption values. Focus on physical properties is recommended for predictive purposes over any classification method. Logs of other species and in regions with different decomposition and combustion dynamics may display different property ranges and consumption results.
Application of QuickBird imagery in fuel load estimation in the Daxinganling region, China
Authors: Jin Sen , Chen Shyh-Chin
Published: August 2012

A high spatial resolution QuickBird satellite image and a low spatial but high spectral resolution Landsat Thermatic Mapper image were used to linearly regress fuel loads of 70 plots with size 30 × 30 m over the Daxinganling region of north-east China. The results were compared with loads from field surveys and from regression estimations by surveyed stand characteristics. The results show that fuel loads were related to stand characteristics, such as stand mean diameter at breast height and stand height. As the QuickBird image using the shadow fraction method represented the stand characteristics well, fuel loads were well estimated from the QuickBird image. QuickBird estimations outperformed those from the lower spatial resolution Thermatic Mapper image. For many fuel classes, the QuickBird estimations were as good as those regressed from surveyed stand characteristics, and thus similar to the surveyed fine and total dead fuel loads. However, coarse fuel loads were not estimated as well using both satellite images owing to their intrinsic low association with stand characteristics. Despite this limitation in estimating coarse fuels, very-high-resolution images such as QuickBird are still valuable in estimating fine fuels, which are critically important in the practice of fire management.
A mathematical model for predicting the maximum potential spotting distance from a crown fire
Authors: Albini Frank A. , Alexander Martin E. , Cruz Miguel G.
Published: August 2012

A mathematical model is presented for predicting the maximum potential spot fire distance from an active crown fire. This distance can be estimated from the height of the flame above the canopy top, wind speed at canopy-top height and final firebrand size (i.e. its residual size on alighting), represented by the diameter of a cylinder of woody char. The complete model system comprises several submodels or components: a model for the height and tilt angle of the wind-blown line-fire flame front, a simplified two-dimensional model of the wind-blown buoyant plume from the fire, an assumed logarithmic wind speed variation with height, and an empirically based model for the burning rate of a wooden cylinder in cross flow, which represents the firebrand. The trajectory of the burning particle is expressed analytically from where it leaves the lower boundary of the plume until it enters the canopy top. Adding the horizontal distance of this flight to that of the point where the particle can no longer be held aloft by the plume flow gives a spotting range that depends on the final diameter of the burning particle. Comparisons of model output with existing information on crown fire spotting distances has initially proved encouraging but further evaluation is warranted.
Estimating the amount of water required to extinguish wildfires under different conditions and in various fuel types
Authors: Hansen Rickard
Published: August 2012

In wildland fires where water is used as the primary extinguishing agent, one of the issues of wildfire suppression is estimating how much water is required to extinguish a certain section of the fire. In order to use easily distinguished and available indicators, the flame length and the area of the active combustion zone were chosen as suitable for the modelling of extinguishing requirements. Using Byram’s and Thomas’ equations, the heat release rate per unit length of fire front was calculated for low-intensity surface fires, fires with higher wind conditions, fires in steep terrain and high-intensity crown fires. Based on the heat release rate per unit length of fire front, the critical water flow rate was calculated for the various cases. Further, the required amount of water for a specific active combustion zone area was calculated for various fuel models. Finally, the results for low-intensity surface fires were validated against fire experiments. The calculated volumes of water can be used both during the preparatory planning for incidents as well as during firefighting operations.
Fire effects on the spatial patterning of soil properties in sagebrush steppe, USA: a meta-analysis
Authors: Sankey Joel B. , Germino Matthew J. , Sankey Temuulen T. , Hoover Amber N.
Published: August 2012

Understanding effects of changes in ecological disturbance regimes on soil properties, and capacity of soil properties to resist disturbance, is important for assessing ecological condition. In this meta-analysis, we examined the resilience of surface soil properties and their spatial patterning to disturbance by fire in sagebrush steppe of North America – a biome currently experiencing increases in wildfire due to climate change. We reviewed 39 studies that reported on soil properties for sagebrush steppe with distinct microsite (undershrub and interspace) patterning that was or was not recently burned. We estimated microsite effects for 21 soil properties and examined the effect of burning on microsite effects during the first year post-fire, before the re-establishment of vegetation. Results indicated that the spatial patterning of biogeochemical resources, in which soil surfaces beneath shrubs are enriched, is resilient to burning. However, microsite effects for soil-surface hydrologic, temperature and erosion characteristics appeared to shift following burning. These shifts appear to create a negative feedback for the spatial patterning of soil properties before vegetation recovery. Relatively long (decades–centuries) historic fire intervals in sagebrush steppe ecosystems likely reinforce spatial patterning of soil resources. However, increased fire frequency might affect the ability for soil resources to withstand change.
Tools to aid post-wildfire assessment and erosion-mitigation treatment decisions
Authors: Robichaud Peter R. , Ashmun Louise E.
Published: August 2012

A considerable investment in post-fire research over the past decade has improved our understanding of wildfire effects on soil, hydrology, erosion and erosion-mitigation treatment effectiveness. Using this new knowledge, we have developed several tools to assist land managers with post-wildfire assessment and treatment decisions, such as prediction models, research syntheses, equipment and methods for field measurements, reference catalogues and databases of past-practice, and spreadsheets for calculating resource valuation and cost–benefit analysis. These tools provide relevant science to post-fire assessment teams and land managers in formats that often can be directly entered into assessment and treatment decision-making protocols. Providing public access to these tools through the internet not only has increased their dissemination, but also has allowed them to be updated and improved as new knowledge and technology become available. The use of these science-based tools has facilitated a broader application of current knowledge to post-fire management in the United States and in other fire-prone areas around the world.
Checkpoint kinase 2 (Chk2) inhibits the activity of the Cdc45/MCM2-7/GINS (CMG) replicative helicase complex
Authors: Ilves Ivar , Tamberg Nele , Botchan Michael R.
Published: August 2012

The replication of eukaryote chromosomes slows down when DNA is damaged and the proteins that work at the fork (the replisome) are known targets for the signaling pathways that mediate such responses critical for accurate genomic inheritance. However, the molecular mechanisms and details of how this response is mediated are poorly understood. In this report we show that the activity of replisome helicase, the Cdc45/MCM2-7/GINS (CMG) complex, can be inhibited by protein phosphorylation. Recombinant
Drosophila melanogaster
CMG can be stimulated by treatment with phosphatase whereas Chk2 but not Chk1 interferes with the helicase activity in vitro. The targets for Chk2 phosphorylation have been identified and reside in MCM subunits 3 and 4 and in the GINS protein Psf2. Interference requires a combination of modifications and we suggest that the formation of negative charges might create a surface on the helicase to allosterically affect its function. The treatment of developing fly embryos with ionizing radiation leads to hyperphosphorylation of Psf2 subunit in the active helicase complex. Taken together these data suggest that the direct modification of the CMG helicase by Chk2 is an important nexus for response to DNA damage.
Growth and Lipid Composition of Winter Flounder Juveniles Reared under Natural and Fixed Photoperiod and Temperature Conditions
Authors: Fraboulet E , Lambert Y , Tremblay R , Audet C
Published: August 2012

In age-0 winter flounder Pseudopleuronectes americanus, a fixed long photoperiod (14.5 h light: 9.5 h dark) applied during the first 45 d postsettlement did not improve growth compared with fish held under natural photoperiod conditions. After being reared under these two regimes until 29 October, juveniles exposed to the long photoperiod after settlement were maintained under the same conditions during the winter, but temperature was not allowed to decrease below 4°C. Juveniles previously exposed to the natural photoperiod were maintained under one of the following conditions: (1) natural photoperiod and natural temperature (1–9°C), (2) natural photoperiod and a minimum winter temperature of 4°C, or (3) long photoperiod and a minimum temperature of 4°C. Most mortality (80%) occurred within the first 2 months of the experiment. Juveniles that experienced the transition from natural to long photoperiod conditions displayed higher growth through the winter than did juveniles exposed to natural conditions; at the end of winter, fish that were transitioned to the long photoperiod were 25% longer (19 mm), were twice as heavy (125 mg), and contained twice as much total lipids (803 μg/mg) and five times more triacylglycerols (24% of total lipids) than juveniles subjected to the natural photoperiod. These results indicate that we may be able to eliminate the winter fasting that occurs under natural conditions and to elicit winter growth in this species by using photoperiod manipulation. In addition, it appears that a decrease in photoperiod is needed for fish to respond to a subsequent increase in photoperiod.

Received November 3, 2009; accepted May 27, 2010