bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of sediment on mountain river erosion
Authors: Schultz Colin
Published: August 2011

Mountain uplift and subsequent water‐powered erosion are powerful and persistent processes shaping the landscape, and understanding the interactions between these two processes has been an area of active research for the past 2 decades. The rate of river erosion has long been considered to scale with stream power, the potential energy dissipated by water as it flows downhill. While widely used, this model has been tested in only a limited number of situations, sometimes with little success. The stream power model, in which erosion rates scale with the area of the upstream drainage basin and the slope of the stream, makes no account for the amount of sediment in the river. Sediment can increase erosion when the overall sediment levels are low or prevent it when the sediment load is high, and the sediment can form an armor‐like cover on the riverbed. (Journal of Geophysical Research‐Earth Surface, doi:10.1029/2009JF001655, 2011)
A climate‐induced threshold in hydrologic response in a semiarid ponderosa pine hillslope
Authors: Mahmood Taufique H. , Vivoni Enrique R.
Published: August 2011

The temporal evolution of spatial hydrologic patterns in systems with strong seasonality in water availability is poorly understood. In this study, we use a distributed hydrologic model to explore the switching between local (vegetative) and nonlocal (topographic) factors in a semiarid ponderosa pine hillslope. Our modeling effort is focused on identifying threshold behavior in the hillslope response due to wetting during the North American monsoon (NAM). We calibrate the model to distributed surface soil moisture data for one summer and then test the model against a broader range of observations over multiple seasons. Model simulations are then used to identify vegetation and topographic controls on spatial patterns in soil moisture and runoff generation. Vegetation patterns primarily influence the hydrologic response during dry summer periods leading to patchiness related to the ponderosa pine stands. The spatial response switches to fine‐scale terrain curvature controls during persistently wet NAM periods. Thus, a climatic threshold involving rainfall and weather conditions during the NAM is identified in the hillslope response when sufficient lateral soil moisture fluxes are activated by high rainfall amounts and the lower evapotranspiration induced by cloud cover. The spatial variability of hillslope soil moisture and runoff generation also increases due to the crossing of this threshold in the seasonal rainfall distribution. Our findings point to the influence of topography and lateral fluxes during summer periods of high wetness in forested hillslopes of the southwestern United States.
Capturing aquifer heterogeneity: Comparison of approaches through controlled sandbox experiments
Authors: Berg Steven J. , Illman Walter A.
Published: August 2011

Groundwater modeling has become a vital component to water supply and contaminant transport investigations. These models require representative hydraulic conductivity (K) and specific storage (Ss) estimates, or a set of estimates representing subsurface heterogeneity. Currently, there are a number of approaches for characterizing and modeling K and Ss heterogeneity in varying degrees of detail, but there is a lack of consensus for an approach that results in the most robust groundwater models with the best predictive ability. The main goal of this study is to compare different heterogeneity modeling approaches (e.g., effective parameters, geostatistics, geological models, and hydraulic tomography) when input into a forward groundwater model and used to predict 16 independent cross‐hole pumping tests. We first characterize a sandbox aquifer through single‐ and cross‐hole pumping tests, and then use these data to construct forward groundwater models of various complexities (both homogeneous and heterogeneous distributions). Two effective parameter models are constructed: (1) by taking the geometric mean of single‐hole test K and Ss estimates and (2) calibrating effective K and Ss estimates by simultaneously matching the response at all ports during a cross‐hole test. Heterogeneous models consist of spatially variable K and Ss fields obtained via (1) kriging single‐hole data; (2) calibrating a geological model; and (3) conducting transient hydraulic tomography (Zhu and Yeh, 2005). The performance of these parameter fields are then tested through the simulation of 16 independent cross‐hole pumping tests. Our results convincingly show that transient hydraulic tomography produces the smallest discrepancy between observed and simulated drawdowns.
Extended multistep outflow method for the accurate determination of soil hydraulic properties near water saturation
Authors: Durner W. , Iden S. C.
Published: August 2011

Inverse modeling of multistep outflow (MSO) experiments is an established and fast method to determine unsaturated hydraulic properties of soils. A disadvantage of the method is its low sensitivity with respect to the hydraulic conductivity function at saturation, which makes the respective estimation very uncertain. Thus, the use of independently measured values for the saturated hydraulic conductivity, Ks, is generally recommended. This involves disadvantages, namely, the effort to conduct additional experiments and the general problems associated with the combination of data from different experimental sources. To overcome this problem, we propose to combine percolation and outflow in one experiment. This extended multistep outflow experiment (XMSO) starts with a completely water‐saturated soil column, on top of which a small amount of water is ponding. The first experimental phase is a saturated percolation under falling‐head conditions. After ponding ceases, the experiment continues as a standard MSO experiment with an unsaturated drainage process. The XMSO experiment is evaluated by inverse modeling, using measurements of cumulative outflow and tensiometric pressure head data. Our analysis of synthetic and real data demonstrates that XMSO yields very accurate estimates of saturated and near‐saturated hydraulic properties, even for soils with structured pore systems. Furthermore, saturated hydraulic conductivities of the supporting porous plate and the soil can be simultaneously determined with great accuracy. We conclude that the XMSO experimental design solves the problem of the identification of near‐saturated hydraulic properties of soil samples and reduces the estimation uncertainty of Ks to a minimum.
Discriminatory power of MicroResp^TM^ analyses across variable spatial scales in semiarid ecological zones
Authors: Tahtamouni Mohammad , Unc Adrian , Lucero Mary , Khresat Sa’eb
Published: August 2011

Indirect assessment of enzymatic activity potential via substrate induced respiration is a common tool used to evaluate variability in soil microbial activity induced by environmental or management variables. The MicroResp™ method for total soil sample catabolic profiling has been employed to estimate divergence in microbial activities under contrasting conditions. Here we evaluate the potential for the method to discriminate across samples exposed to similar ecological conditions at distinct geographical locations, and across samples exposed to distinct soil management conditions. Samples used in this report came from four spatially distinct arid or semi arid locations in New Mexico, USA and Jordan. For all scales of comparison, similar conditions such as rhizosphere and non-rhizosphere soils, disturbance levels, soil depth and distance from plants were considered as factors.Catabolic profiles vary within and between sampling locations as a function of soil characteristics as induced by proximity to plants, plant species, sampling depth and land disturbance. Substrate utilization potential was expectedly larger in the rhizosphere soils versus non-rhizosphere soil. Rhizosphere activity varied across sampling locations. Surprisingly, variation among plant species within a location was minimal.In summary, fast degradable substrates can distinguish between rhizosphere and non-rhizosphere soils across small scales. Slightly more stable compounds such as aminoacids or fatty acid esters are better descriptors of catabolic potential differences on non-rhizosphere soils across small to large scales. Cellulose degradation only induced significantly differential respiration in samples collected across large spatial scales.
Managing Erp System Risk in SMEs: A Multiple Case Study
Authors: Poba-Nzaou Placide , Raymond Louis
Published: August 2011

ERP systems are increasingly accessible to small and medium-sized enterprises (SMEs). If the potential benefits of these systems are significant, the same applies to the risk associated with their implementation. A number of authors emphasize that IS risk management is most effective when it is initiated at the earliest possible moment in the system's lifecycle, that is, at the adoption phase. But how do SMEs actually manage the risk of ERP implementation during the ERP adoption process? The research objectives are (1) to identify and describe the influence of the SMEs’ context on their implementation risk exposure, and (2) to understand whether and how, within the adoption process, SMEs actually manage the risk of implementing an ERP system supplied by an ERP vendor, with open source software, or through in-house development. In order to do so, four case studies of SMEs having implemented an ERP system were undertaken. The study shows that to manage risk at the adoption stage, SMEs can proceed in a rather intuitive, informal and unstructured manner, that is explicitly based however upon an architecture of basic principles, policies and practices.
Pre-breakdown negative differential resistance in thin oxide film: Conductive-atomic force microscopy observation and modelling
Authors: Delcroix P. , Blonkowski S. , Kogelschatz M.
Published: August 2011

Negative differential resistance in thin nitrated silicon oxide and silicon oxide films is observed during current voltage measurements using conductive atomic force microscopy in ultra-high vacuum if the voltage sweep direction is reversed just before the dielectric breakdown voltage is reached. Current voltage characteristics are discussed using a trap assisted tunneling model. The resulting concentration of traps needed in order to reproduce the experimental characteristic leads to the consideration of a filamentlike conduction model, rather than a trap assisted tunneling model in which traps are randomly generated. The model reproduces well the effect of the voltage ramp parameters on the experimental current voltage characteristics, including the negative differential resistance. The effect of the growth dynamic parameters on the current voltage characteristics and the occurrence of the pre-breakdown negative differential resistance are discussed with the help of the model.
Understanding tube-like electron emission from nanographite clustered films
Authors: Koh A. T. T. , Foong Y. M. , Yu J. , Chua Daniel H. C. , Wee Andrew T. S. , Kudo Y. , Okano K.
Published: August 2011

Diamond-like carbon and amorphous carbon films are known for their high smoothness root mean square values which can be as low as 0.1 nm. When used in field emission, physical aspects of enhancement are often disregarded for such flat film emitters. However, it is proven that these films may not be as flat as they appear to be. We present an experimental validation that shows a tube or needle-like emission mechanism for nanosized graphite clusters embedded in an amorphous carbon matrix. Films were deposited with in situ heating at 100, 400 and 700 °C and enhancement factors were seen to increase twofold as temperature was increased. By varying the anode-cathode distances, the films exhibited a distance dependency that is only observed for tubes and needle structures. This suggests that flat films can exhibit an emission mechanism akin to carbon nanotubes, thus confirming the presence of conductive channels within the films for nanoclustered amorphous carbon films.
Molecular dynamics simulations for the prediction of thermal conductivity of bulk silicon and silicon nanowires: Influence of interatomic potentials and boundary conditions
Authors: Abs da Cruz Carolina , Termentzidis Konstantinos , Chantrenne Patrice , Kleber Xavier
Published: August 2011

The reliability of molecular dynamics (MD) results depends strongly on the choice of interatomic potentials and simulation conditions. Five interatomic potentials have been evaluated for heat transfer MD simulations of silicon, based on the description of the harmonic (dispersion curves) and anharmonic (linear thermal expansion) properties. The best interatomic potential is the second nearest-neighbor modified embedded atom method potential followed by the Stillinger-Weber, and then the Tersoff III. However, the prediction of the bulk silicon thermal conductivity leads to the conclusion that the Tersoff III potential gives the best results for isotopically pure silicon at high temperatures. The thermal conductivity of silicon nanowires as a function of cross-section and length is calculated, and the influence of the boundary conditions is studied for those five potentials.
Structure-property relationships in self-assembled metalorganic chemical vapor deposition–grown CoFe2O4–PbTiO3 multiferroic nanocomposites using three-dimensional characterization
Authors: Pan Mengchun , Liu Yuzi , Bai Guoren , Hong Seungbum , Dravid Vinayak P. , Petford-Long Amanda K.
Published: August 2011

Multiferroic nanocomposites, consisting of branched, ferrimagnetic CoFe2O4 filaments and large protruding PbTiO3 particles embedded in a piezoelectric PbTiO3 matrix, have been fabricated by co-deposition using metalorganic chemical vapor deposition. Branched CoFe2O4 filaments reduce the CoFe2O4/PbTiO3 interfacial strain and induce a perpendicular magnetic anisotropy. Three-dimensional characterizations reveal that in addition to the c-domain, grains with a second orientation in PbTiO3 particles contribute to an additional four apparent variants of polarization. In contrast, the PbTiO3 matrix exhibits only c-domain polarization with a smaller magnitude. The smaller piezoresponse results from the constraints imposed by the branched CoFe2O4 filaments. Three-dimensional microstructure and property analysis provide a comprehensive insight on the structure-property relationship of multiferroic nanocomposites grown by metalorganic chemical vapor deposition.
Dynamical regimes on the Cl + H2 collisions: Inelastic rainbow scattering
Authors: González-Sánchez L. , Aldegunde J. , Jambrina P. G. , Aoiz F. J.
Published: August 2011

While Cl + H2 reactive collisions have been a subject of numerous experimental and theoretical studies, inelastic collisions leading to rotational energy transfer and/or vibrational excitation have been largely ignored. In this work, extensive quantum mechanical calculations covering the 0.5–1.5 eV total energy range and various initial rovibrational states have been carried out and used to perform a joint study of inelastic and reactive Cl + H2 collisions. Quasiclassical trajectories calculations complement the quantum mechanical results. The analysis of the inelastic transition probabilities has revealed the existence of two distinct dynamical regimes that correlate with low and high impact parameters, b, and are neatly separated by glory scattering. It has been found that while high-b collisions are mainly responsible for |Δj| = 2 transitions which dominate the inelastic scattering, they are very inefficient in promoting higher |Δj| transitions. The effectiveness of this type of collision also drops with rotational excitation of H2. In contrast, reactive scattering, that competes with \documentclass[12pt]{minimal}\begin{document}$|\Delta j|\: \break >$\end{document}|Δj|> 2 inelastic transitions, is exclusively caused by low-b collisions, and it is greatly favored when the reactants get rotationally excited. Previous studies focusing on the reactivity of the Cl + H2 system established that the van der Waals well located in the entrance channel play a key role in determining the mechanism of the collisions. Our results prove this to be also a case for inelastic processes, where the origin of the double dynamical regime can be traced back to the influence exerted by this well that shapes the topology of the entrance channel of the Cl–H2 system.
Small-signal analysis of a fully rated converter wind turbine
Authors: Caliao Nolan D.
Published: August 2011

Small signal analysis of the fully rated converter wind turbine connected to a large power system was undertaken. The dynamic behaviour of the fully rated converter wind turbine was investigated using eigenvalue analysis. Eigenvalue analysis was undertaken to determine the influence of the network short circuit level on the networks dominant eigenvalues. It was shown that the strength of the transmission system does not influence the dynamic behaviour of the generator of the fully rated converter wind turbine.
Functionalization of cubic boron nitride films with rhodamine B and their fluorescent properties
Authors: Liu W. M. , Zhang H. Y. , Wang P. F. , Ye Q. , Yang Y. , He B. , Bello I. , Lee S. T. , Zhang W. J.
Published: August 2011

Fluorophore-functionalized cubic boron nitride (cBN) films grown by chemical vapor deposition were achieved by immobilizing rhodamine B isothiocyanate onto their surfaces. To perform the immobilization, the cBN substrates were modified with amino groups by photochemical reaction between hydrogen-terminated cBN surfaces and allylamine. The surface analysis of hydrogen-terminated cBN films surfaces and after functionalization with x-ray photoelectron spectroscopy verified that rhodamine B was indeed attached to the cBN surfaces with covalent bonding. The rhodamine B-functionalized cBN surfaces showed significant variation in fluorescent spectra and confocal imaging upon the treatment in acidic or basic solutions.
Modelling the resistive state in a transition edge sensor
Authors: Kozorezov A. , Golubov A. A. , Martin D. D. E. , de Korte P. A. J. , Lindeman M. A. , Hijmering R. A. , van der Kuur J. , Hoevers H. F. C. , Gottardi L. , Kupriyanov M. Yu. , Wigmore J. K.
Published: August 2011

We have developed a model for the resistive transition in a transition edge sensor (TES) based on the model of a resistively and capacitively shunted junction, taking into account phase-slips of a superconducting system across the barriers of the tilted washing board potential. We obtained analytical expressions for the resistance of the TES, R(T, I), and its partial logarithmic derivatives αI and βI as functions of temperature and current. We have shown that all the major parameters describing the resistive state of the TES are determined by the dependence on temperature of the Josephson critical current, rather than by intrinsic properties of the S-N transition. The complex impedance of a pristine TES exhibits two-pole behaviour due to its own intrinsic reactance.
Concentration dependence of drift and magnetoresistance ballistic mobility in a scaled-down metal-oxide semiconductor field-effect transistor
Authors: Arora Vijay K. , Shafinaz Zainal Abidin Mastura , Tembhurne Saurabh , Riyadi Munawar A.
Published: August 2011

The degradation of ballistic mobility in a metal-oxide semiconductor field-effect transistor is attributed to the nonstationary ballistic injection from the contacts as the length of a channel shrinks to the length smaller than the scattering-limited mean free path. Apparent contradiction between the rise of magnetoresistance mobility and fall of drift mobility with increasing channel concentration is attributed to scattering-dependent magnetoresistance factor. The ballistic mean free path of injected carriers is found to be substantially higher than the long-channel drift mean free path. Excellent agreement with the experimental data on length-limited ballistic mobility is obtained.
Effect of relaxation state on nucleation and grain growth of nanoscale quasicrystal in Zr-based bulk metallic glasses prepared under various cooling rates
Authors: Saida Junji , Deny Setyawan Albertus , Matsubara Eiichiro
Published: August 2011

Zr65Al7.5Ni10Cu12.5Pd5 bulk metallic glasses (BMGs) in various relaxation states were prepared under different cooling rates. The grain growth rate of the primary quasicrystal was examined near the crystallization temperature. It was approximately 1 × 10−9 m/s in less relaxed BMGs and approximately twice as large in relaxed BMGs. In contrast, the calculated homogeneous nucleation rate of the less relaxed samples was five to ten times higher (5 × 1019–1 × 1020/m3s) than those in the relaxed BMGs. The results indicate that the relaxation state of glassy alloys has a marked effect on nucleation and grain growth behaviors.
Nanowires improved charge separation and light utilization in metal-oxide solar cells
Authors: Cheng Wei-Yun , Lin Yi-Feng , Lu Shih-Yuan
Published: August 2011

The power conversion efficiencies of electrodeposited Cu2O/ZnO p-n junction based solar cells are significantly improved by sandwiching a layer of spin-coated CdS nanowires (NWs) in between the electrochemically deposited Cu2O and ZnO layers. With the inclusion of the CdS NWs, there is observed a 5 fold improvement in the conversion efficiency, from 0.12% to 0.6%, as compared with that of the plain Cu2O/ZnO cell. The improvement is attributed to the enlarged p-n interface area and enhanced light harvesting, charge separation, and electron transport made possible by incorporating the single crystalline, relatively low band gap CdS NWs.
Enhanced electroluminescence from the fluorine-plasma implanted Ni/Au-AlGaN/GaN Schottky diode
Authors: Li B. K. , Wang M. J. , Chen K. J. , Wang J. N.
Published: August 2011

The effect of fluorine-plasma (F-plasma) implantation on the current-voltage (I-V) and electroluminescence (EL) characteristics of Ni/Au-AlGaN/GaN Schottky diodes have been investigated. The observed EL spectrum is dominated by the GaN near band edge emissions. The threshold current of the EL emission for F-plasma implanted diodes is significantly lower than that for the previously reported diodes without the F-plasma implantation. This reduction of threshold current results from the presence of negatively charged F-centers in AlGaN layer which leads to upward band bending of AlGaN layer and enhanced hole injection by multi-step tunneling process through AlGaN layer. The magnitude of the upward banding in AlGaN layer is estimated to be 0.36 eV by analyzing the forward-biased I-V characteristics.
Thermally assisted resistive switching in Pr0.7Ca0.3MnO3/Ti/Ge2Sb2Te5 stack for nonvolatile memory applications
Authors: Siddik Manzar , Jung Seungjae , Park Jubong , Lee Wootae , Kim Seonghyun , Lee Joonmyoung , Shin Jungho , Park Sangsu , Lee Daeseok , Kim Insung , Hwang Hyunsang
Published: August 2011

We propose a low power, high-performance nanoscale (φ = 150 nm) resistive memory device having a Ge2Sb2Te5/Ti/Pr0.7Ca0.3MnO3 (GST/Ti/PCMO) structure. As a thermoelectric heater and/or thermal barrier, GST accelerates the Ti/PCMO interfacial redox process thermally by enhancing the mobility of oxygen ions and minimizes the loss of local heat. Improvement of the memory performances and voltage-time dilemma issue is achieved by adopting this type of thermally assisted process.
Fabrication of a gel particle array in a microfluidic device for bioassays of protein and glucose in human urine samples
Authors: Lin Ling , Gao Zhaoxin , Wei Huibin , Li Haifang , Wang Feng , Lin Jin-Ming
Published: August 2011

This paper describes a simple method for fabricating a series of poly(ethylene glycol) diacrylate (PEG-DA) hydrogel microstructures inside microfluidic channels as probe for proteins and glucose. In order to demonstrate the feasibility of this newly developed system, bovine serum albumin (BSA) was chosen as a model protein. PEG microcolumns were used for the parallel detection of multiple components. Using tetrabromophenol blue (TBPB) and the horseradish peroxidase/glucose oxidase reaction system, bovine serum albumin (BSA) and glucose in human urine were detected by color changes. The color changes for BSA within a concentration range of 1–150 μM, and glucose within a range of 50 mM–2 M could be directly distinguished by eyes or precisely identified by optical microscope. To show the practicability of the gel particle array, protein and glucose concentrations of real human urine samples were determined, resulting in a good correlation with hospital analysis. Notably, only a 5 µL sample was needed for a parallel measurement of both analytes. Conveniently, no special readout equipment or power source was required during the diagnosis process, which is promising for an application in rapid point-of-care diagnosis.
The role of electric field polarization of the incident laser beam in the short pulse damage mechanism of pulse compression gratings
Authors: Hocquet Steve , Neauport Jerome , Bonod Nicolas
Published: August 2011

We investigate the short pulse laser induced damage initiation mechanism on multilayer dielectric pulse compression gratings. We report that damages initiate at the edge of the grating pillars opposite to the incoming wave. It demonstrates, at a nanometer scale, the role of the electric field in the damage process coupled with periodic ripple pattern developing along the polarization direction. We avoid the formation of ripples by illuminating the diffraction grating in TM polarization and measure a significantly improved laser induced damage threshold associated with a strong decrease of the electric field in the grating structure.
Sensitivity to First- and Second-Order Drifting Gratings in 3-Month-Old Infants
Authors: Armstrong Vickie , Maurer Daphne , Ellemberg Dave , Lewis Terri L
Published: August 2011

In two experiments, we investigated 3-month-old infants' sensitivity to first- and second-order drifting gratings. In Experiment 1 we used forced-choice preferential looking with drifting versus stationary gratings to estimate depth modulation thresholds for 3-month-old infants and a similar task for a comparison group of adults. Thresholds for infants were more adult-like for second-order than first-order gratings. In Experiment 2, 3-month-olds dishabituated to a change in first-order orientation, but not to a change in direction of first- or second-order motion. Hence, results from Experiment 1 were likely driven by the perception of flicker rather than motion. Thus, infants' sensitivity to uniform motion is slow to develop and appears to be driven initially by flicker-sensitive mechanisms. The underlying mechanisms have more mature tuning for second-order than for first-order information.
The Hollow-Face Illusion in Infancy: Do Infants See a Screen Based Rotating Hollow Mask as Hollow?
Authors: Tsuruhara Aki , Nakato Emi , Otsuka Yumiko , Kanazawa So , Yamaguchi Masami K , Hill Harold
Published: August 2011

We investigated whether infants experience the hollow-face illusion using a screen-based presentation of a rotating hollow mask. In experiment 1 we examined preferential looking between rotating convex and concave faces. Adults looked more at the concave—illusory convex—face which appears to counter rotate. Infants of 7- to 8-month-old infants preferred the convex face, and 5- to 6-month-olds showed no preference. While older infants discriminate, their preference differed from that of adults possibly because they don't experience the illusion or counter rotation. In experiment 2 we tested preference in 7- to 8-month-olds for angled convex and concave static faces both before and after habituation to the stimuli shown in experiment 1. The infants showed a novelty preference for the static shape opposite to the habituation stimulus, together with a general preference for the static convex face. This shows that they discriminate between convex and concave faces and that habituation to either transfers across a change in view. Seven- to eight-month-olds have been shown to discriminate direction of rigid rotation on the basis of perspective changes. Our results suggest that this, perhaps together with a weaker bias to perceive faces as convex, allows these infants to see the screen-based hollow face as hollow even though adults perceive it as convex.
The effects of wind on the flame characteristics of individual leaves
Authors: Cole Wesley J. , Dennis McKaye H. , Fletcher Thomas H. , Weise David R.
Published: August 2011

Individual cuttings from five shrub species were burned over a flat-flame burner under wind conditions of 0.75–2.80 m s–1. Both live and dead cuttings were used. These included single leaves from broadleaf species as well as 3 to 5 cm-long branches from coniferous and small broadleaf species. Flame angles and flame lengths were determined by semi-automated measurements of video images. Additional data, such as times and temperatures corresponding to ignition, maximum flame height and burnout were determined using video and infrared images. Flame angles correlated linearly with wind velocity. They also correlated with the Froude number when either the flame length or flame height was used. Flame angles in individual leaf experiments were generally 50 to 70% less than flame angles derived from Froude number correlations reported in the literature for fuel-bed experiments. Although flame angles increased with fuel mass and moisture content, they were unaffected by fuel species. Flame lengths and flame heights decreased with moisture contents and wind speed but increased with mass. In most cases, samples burned with wind conditions ignited less quickly and at lower temperatures than samples burned without wind. Most samples contained moisture at the time of ignition. Results of this small-scale approach (e.g. using individual cuttings) apply to ignition of shrubs and to flame propagation in shrubs of low bulk density. This research is one of the few attempts to characterise single-leaf and small-branch combustion behaviour in wind and is crucial to the continued development of a semi-empirical shrub combustion model.
Fuel structural traits modulating soil temperatures in different species patches of Mediterranean Basin shrublands
Authors: Santana Victor M. , Baeza M. Jaime , Vallejo V. Ramón
Published: August 2011

The ability of a fuel to burn is determined by its flammability, a property that varies from one species to another and is partially determined by different fuel structural traits such as surface-to-volume ratio of twigs and leaves, retention of standing dead twigs, canopy architecture and bulk density. Our aim was to assess the role of these fuel structural traits in modulating soil temperatures under patches of different species. The results showed that there were contrasting differences in the fuel-structure complex among different species patches in Mediterranean Basin shrublands. The differences in the fuel structure were important in modulating soil temperature because, regardless of the total fuel load, the highest temperatures were found under the species with the highest loads and densities of dead fine fuel. Surprisingly, temperatures under herbaceous species were high in relation to shrubby species; however, temperature residence times were shorter. Therefore, management strategies that promote species that accumulate low contents of fine dead fuel could be crucial for attaining less severe fires with a reduced effect on ecosystem functioning.
Nuclear envelope starts with a clean sheet
Authors: Short Ben
Published: August 2011

After mitosis, nuclear membranes form directly from ER cisternae before nuclear pore complex reassembly.
Ulrike Eggert: Big things from small molecules
Authors: Sedwick Caitlin
Published: August 2011

Eggert uses RNAi and chemistry to develop novel tools for investigating cytokinesis.
The mitochondrial import protein Mim1 promotes biogenesis of multispanning outer membrane proteins
Authors: Becker Thomas , Wenz Lena-Sophie , Krüger Vivien , Lehmann Waltraut , Müller Judith M. , Goroncy Luise , Zufall Nicole , Lithgow Trevor , Guiard Bernard , Chacinska Agnieszka , Wagner Richard , Meisinger Chris , Pfanner Nikolaus
Published: August 2011

The mitochondrial outer membrane contains translocase complexes for the import of precursor proteins. The translocase of the outer membrane complex functions as a general preprotein entry gate, whereas the sorting and assembly machinery complex mediates membrane insertion of β-barrel proteins of the outer membrane. Several α-helical outer membrane proteins are known to carry multiple transmembrane segments; however, only limited information is available on the biogenesis of these proteins. We report that mitochondria lacking the mitochondrial import protein 1 (Mim1) are impaired in the biogenesis of multispanning outer membrane proteins, whereas overexpression of Mim1 stimulates their import. The Mim1 complex cooperates with the receptor Tom70 in binding of precursor proteins and promotes their insertion and assembly into the outer membrane. We conclude that the Mim1 complex plays a central role in the import of α-helical outer membrane proteins with multiple transmembrane segments.
Sedimentary record of tectonic and climatic erosional perturbations in an experimental coupled catchment‐fan system
Authors: Rohais Sébastien , Bonnet Stéphane , Eschard Rémi
Published: August 2011

This article deals with the stratigraphic record of a climatic or tectonic perturbation of an experimental coupled catchment‐fan system. Following Bonnet & Crave's results (2003), which suggest that it is possible to differentiate between climatic or tectonic causes of surface uplift of an erosional topography from the record of sediment flux output, we design a new experimental device to test this proposition in the sedimentary signal. This device allows the study of a coupled erosion–sedimentation system at the laboratory scale for given and changing uplift and rainfall rates. On the basis of experimental results, we propose a methodology to study alluvial fan architecture from large‐scale geometries to stacking pattern and sequence analysis. In these experiments, the erosional perturbation resulting from climate or tectonic forcing induces a typical dynamic in terms of both sediment supply and the ratio between the sediment and water supply, which controls the transport capacity. The four possible forcings (rainfall rate and uplift rate increase or decrease, respectively) then result in unique dynamics of the combined parameters such as the fan slope, apex aggradation, mean sedimentation rate, grain size distribution, bed thickness and frequency and facies stacking. We first analyse large‐scale geometries (onlap, toplap, downlap or truncation) and then fine‐scale sedimentological features (fining, thinning, coarsening, thickening) in order to discriminate the nature of the forcing. This conceptual model could be adapted to real world alluvial fans in order to recognize and separate the driving mechanisms from each other.
Joint protection in haemophilia
Authors: RODRIGUEZ‐MERCHAN E. C. , JIMENEZ‐YUSTE V. , AZNAR J. A. , HEDNER U. , KNOBE K. , LEE C. A. , LJUNG R. , QUEROL F. , SANTAGOSTINO E. , VALENTINO L. A. , CAFFARINI A.
Published: August 2011

Summary.  Haemarthroses (intra‐articular haemorrhages) are a frequent finding typically observed in patients with haemophilia. Diagnosis and treatment of these bleeding episodes must be delivered as early as possible. Additionally, treatment should ideally be administered intensively (enhanced on‐demand treatment) until the resolution of symptoms. Joint aspiration plays an important role in acute and profuse haemarthroses as the presence of blood in the joint leads to chondrocyte apoptosis and chronic synovitis, which will eventually result in joint degeneration (haemophilic arthropathy). Ultrasonography (US) is an appropriate diagnostic technique to assess the evolution of acute haemarthrosis in haemophilia, although magnetic resonance imaging remains the gold standard as far as imaging techniques are concerned. Some patients experience subclinical haemarthroses, which eventually tend to result in some degree of arthropathy, especially in the ankles. Nowadays, the most effective way of protecting these patients is primary prophylaxis, which in practice changes severe haemophilia into moderate haemophilia, preventing or at least minimizing the occurrence of haemarthrosis. If primary prophylaxis is, for whatever reason not an option, secondary prophylaxis and enhanced on demand treatment should be considered. Two alternatives are available for inhibitor patients: (i) control of haemostasis using by‐passing agents (rFVIIa or aPCCs) either as enhanced on demand treatment or secondary prophylaxis, as appropriate, following the same basic principles used for non‐inhibitor patients and (ii) immune tolerance induction (ITI) to eradicate the inhibitor.
Caspase‐3/caspase‐8, bax and bcl2 in pulps of human primary teeth with physiological root resorption
Authors: RODRIGUES LUCIANA V. , DEL PUERTO HELEN L. , BRANT JULIANA M. C. , LEITE RÔMULO C. , VASCONCELOS ANILTON C.
Published: August 2011

International Journal of Paediatric Dentistry 2011; 22: 52–59

Objective.  Physiological root resorption is a programmed event that takes place in primary teeth leading to elimination of all root structures. The mechanism behind pulp elimination indicates apoptosis, but its pathway has not been well characterised yet. To better understand this event, we evaluated the gene expression of bax, bcl‐2, caspase‐3 and caspase‐8 through real‐time polymerase chain reaction (PCR) and immunohistochemistry expression of Caspase‐8 and Bax in pulps.

Methods.  Samples were split into two groups: pulps from primary teeth with physiological root resorption (n = 40) and control (n = 40), pulps from permanent teeth. Samples of each group were split into PCR (n = 20) and immunohistochemistry (n = 20).

Results.  Pulps from primary teeth showed a higher caspase‐3 mRNA level than pulps from permanent teeth. The expression of bax gene was more intense than caspase‐8 but both did not show difference between groups. The bcl‐2 mRNA level was incipient and similar between groups. Histopath slides did not show any evidence of inflammatory infiltration, which implies that extrinsic via is not likely to be involved. Immunohistochemistry reaction to Bax and Caspase‐8 supported PCR results.

Conclusions.  Pulp apoptosis is likely to occur via caspase‐3 activation through the mitochondrial pathway.
The Mycobacterium tuberculosis Ag85A is a novel diacylglycerol acyltransferase involved in lipid body formation
Authors: Elamin Ayssar A. , Stehr Matthias , Spallek Ralf , Rohde Manfred , Singh Mahavir
Published: August 2011

Mycobacterium tuberculosis accumulates large amounts of triacylglycerol (TAG) which acts as storage compounds for energy and carbon. The mycobacterial triacylglycerols stored in the form of intracellular lipid droplets are essential for long‐term survival of M. tuberculosis during a dormant state. We report here that when the M. tuberculosis mycolytransferase Ag85A is overexpressed in Mycobacterium smegmatis mc2155, cell morphology was changed and the cells became grossly enlarged. A massive formation of lipid bodies and a change in lipid pattern was observed simultaneously. We suspected a possible role of Ag85A in the acyl lipid metabolism and discovered that the enzyme possesses acyl‐CoA:diacylglycerol acyltransferase (DGAT) activity in addition to its well‐known function as mycolyltransferase. Ag85A mediates the transesterification of diacylglycerol using long‐chain acyl‐CoA as acyl donors. The Km and Kcat values for palmitoleoyl‐coenzyme A were 390 µM and 55.54 min−1 respectively. A docking model suggests that palmitoleoyl‐coenzyme A and 1,2‐dipalmitin occupy the same active site as trehalose 6,6′‐dimycolate and trehalose 6′‐monomycolate. The site‐directed Ser126Ala mutation of the active site proved that this residue is involved in the catalytic activity of this enzyme. Although not proven conclusively for dormant stage of M. tuberculosis, our novel finding about the synthesis of TAGs by Ag85A strongly suggests that Ag85A may play a significant role in the formation of lipid storage bodies and thus also in the establishment and maintenance of a persistent tuberculosis infection.
Lactobacillus brevis responds to flavonoids through KaeR, a LysR‐type of transcriptional regulator
Authors: Pande Santosh G. , Pagliai Fernando A. , Gardner Christopher L. , Wrench Algevis , Narvel Raed , Gonzalez Claudio F. , Lorca Graciela L.
Published: August 2011

The ability of transcription factors to respond to flavonoids as signal molecules was investigated in Lactobacillus brevis. Through in vitro screening of a small library of flavonoids, LVIS1989 (KaeR), a LysR‐type transcriptional regulator (LTTR), was identified as responsive to kaempferol. The modulation of KaeR activity by flavonoids was characterized in vivo and in vitro. DNase I footprint assays identified the binding of KaeR at two distinctive sites, one in the intergenic region between LVIS1988 and kaeR (−39 to +2) and another within LVIS1988 (−314 to −353, from kaeR translational start point). EMSA assays revealed that both binding sites are required for KaeR binding in vitro. Furthermore, KaeR–DNA interactions were stabilized by the addition of kaempferol (20 µM). In vivo qRT‐PCR experiments performed in L. brevis confirmed that the divergently transcribed genes LVIS1988, LVIS1987 and LVIS1986 and kaeR are upregulated in the presence of kaempferol, indicating the role of KaeR as a transcriptional activator. Transcriptional lacZ fusions using Bacillus subtilis as a surrogate host showed that expression of kaeR and LVIS1988 were induced by the presence of the flavonoid. These results indicate that KaeR belongs to a small and poorly understood group of LTTRs that are positively autoregulated in the presence of a ligand.
FraC/FraD‐dependent intercellular molecular exchange in the filaments of a heterocyst‐forming cyanobacterium, Anabaena sp.
Authors: Merino‐Puerto Victoria , Schwarz Heinz , Maldener Iris , Mariscal Vicente , Mullineaux Conrad W. , Herrero Antonia , Flores Enrique
Published: August 2011

The filamentous, heterocyst‐forming cyanobacteria are multicellular organisms in which two different cell types, the CO2‐fixing vegetative cells and the N2‐fixing heterocysts, exchange nutrients and regulators. In Anabaena sp. strain PCC 7120, inactivation of sepJ or genes in the fraC operon (fraC, fraD and fraE) produce filament fragmentation. SepJ, FraC and FraD are cytoplasmic membrane proteins located in the filament's intercellular septa that are needed for intercellular exchange of the fluorescent tracer calcein (622 Da). Transmission electron microscopy showed an alteration in the heterocyst cytoplasmic membrane at the vegetative cell‐heterocyst septa in ΔfraC and ΔfraD mutants. Immunogold labelling of FraD confirmed its localization in the intercellular septa and clearly showed the presence of part of the protein between the cytoplasmic membranes of the adjacent cells. This localization seemed to be affected in the ΔfraC mutant but was not impaired in a ΔsepJ mutant. Intercellular transfer of a smaller fluorescent tracer, 5‐carboxyfluorescein (374 Da), was largely impaired in ΔfraC, ΔfraD and double ΔfraC‐ΔfraD mutants, but much less in the ΔsepJ mutant. These results show the existence in the Anabaena filaments of a FraC/FraD‐dependent intercellular molecular exchange that does not require SepJ.
Imprint of the Late Palaeozoic Ice Age on stratigraphic and carbon isotopic patterns in marine carbonates of the Orogrande Basin, New Mexico, USA
Authors: KOCH JESSE T. , FRANK TRACY D.
Published: August 2011

The Permian records one of the most extreme climate transitions of the Phanerozoic, yet the climatic and environmental dynamics of this interval and their effects on neritic carbonate systems remain poorly constrained. New stratigraphic and carbon isotope records from uppermost Pennsylvanian to Lower Permian strata of the Orogrande Basin in south‐central New Mexico, USA, provide fresh insights into the response of palaeotropical carbonate systems to the growth and demise of ice sheets on Gondwana. The earliest Permian acme of glaciation is recorded in the Orogrande Basin as a series of subaerial exposure surfaces marked by highly variable δ13C values that tend toward values as low as −6‰. These stratigraphic and isotopic patterns are interpreted to reflect the retreat of the sea from the basin during glacial expansion. Younger (Lower Sakmarian to Kungurian) strata, deposited during the long decline of the Late Paleozoic Ice Age, are characterized overall by higher and more uniform δ13C values (+2 to +5‰) and show no evidence of long‐term subaerial exposure. However, these strata record two short‐lived excursions toward more negative δ13C values. These excursions occur through intervals that record shifts toward shallower and more restricted conditions in the Orogrande Basin. The timing of these shifts corresponds to two periods of glacial expansion across eastern Australia during Late Sakmarian to Early Artinskian and Kungurian time. These relationships suggest that pulses of glacial expansion in eastern Gondwana were of sufficient magnitude to have caused relative sea‐level fall, and possibly environmental change, in the Orogrande Basin. The results from this study suggest that marine chemistry, depositional environments and sea‐level in the Orogrande Basin were profoundly influenced by epochs of Gondwanan glaciation. These inferences help improve the understanding of how palaeotropical carbonate systems responded to the effects of cryospheric changes during the acme and waning stages of the Late Palaeozoic Ice Age.
Is Meru a specialized noterid (Coleoptera, Adephaga)?
Authors: DRESSLER CARINA , GE SI‐QIN , BEUTEL ROLF G.
Published: August 2011

Larval characters of Meru were extracted from the recently published description and added to an extensive data matrix from an earlier study on the phylogenetic position of the genus and family. The results confirm the earlier postulated clade Meruidae + Noteridae with strong support. The larvae share several characteristics with noterid larvae, notably the specific head shape, with the greatest width close to the foramen occipitale, the fissure‐shaped posterior tentorial grooves at the posterior margin of the head capsule and the anteriorly cleft prementum. From a formal point of view, it would be justified to treat Meru as a subgroup of Noteridae (if the larva is properly identified). We refute the placement of Meruidae as a sister group of the remaining Dytiscoidea (including Noteridae). The new larval characters are valuable and informative, but a small set of external features is not sufficient for a reliable placement of Meruidae.
Young, gifted, and caring: A project narrative of young carers, their mental health, and getting them involved in education, research and practice
Authors: McAndrew Sue , Warne Tony , Fallon Debbie , Moran Paul
Published: August 2011

Young carers are a global phenomenon. The UK estimates it has in excess of 175 000 young carers, the onset of their caring role often occurring between 8 and 10 years of age. Of these, 17 000 are caring for a parent who has severe mental illness, a significant factor for children entering the health and social care system, as up to 60% experience mental health difficulties themselves. This paper reports on the outcome of a participatory project aimed at better understanding the needs of young people. A World Café event was hosted, bringing together those involved in promoting the mental health of young people in a partnership consortium. The event was led by young service users and carers. Important issues raised by the young carers were being excluded from being included; stuck in the here and now, ignoring the future; a hole in the net; and ensuring the hidden is on the agenda. The World Café gave the university the privilege of insight into what local young carers need to improve their mental health, and more importantly, how we can utilize our skills to help them achieve their goals.