bluuebunny/crossref_metadata_2025 huggingface dataset:
Biochemical oxygen demand and algae: Fractionation of phytoplankton and nonphytoplankton respiration in a large river
Authors: Cohen Ronald R. H.
Published: February 2008

Mass balance equations for dissolved oxygen in streams are formulated to account for, among other variables, algal respiration (R), and biochemical oxygen demand (BOD). The oxygen consumption measured in primary productivity‐respiration analyses is not R but is total community oxygen consumption (TCOC), and BOD measurements are complicated by undefined algal components. Ultimate BOD was found to be 0.24 mg of O2 consumed per μg chlorophyll a and carbonaceous BOD was 0.20 per μ‐g chlorophyll a in excess of background BOD. The results were similar for live and dead algae. Phytoplankton respiration was fractionated from nonphytoplankton oxygen consumption (NPOC) by the regression of respiration against chlorophyll a to obtain a y intercept of zero chlorophyll. The intercepts, NPOC, closely matched O2 consumption measured when phytoplankton biomass was very low. Phytoplankton respiration, calculated as the residual of the difference between TCOC and NPOC, ranged from 0.2 to 1.5 (mean = 0.88) mg O2 per mg chlorophyll a per hour, close to the literature value of 1 (in cultures). Depth‐integrated (DI) phytoplankton respiration was 1/4 to 1/3 of DI gross primary productivity and 1–3% of maximum primary productivity. The separation of phytoplankton R and NPOC permitted the demonstration that R probably is not a simple function of productivity.
Periodic covariance stationarity of multivariate periodic autoregressive moving average processes
Authors: Ula Taylan A.
Published: February 2008

Periodic (covariance) Stationarity conditions for multivariate periodic autoregressive moving average (PARMA) processes are investigated. It follows from a previous work that a necessary and sufficient condition for the periodic Stationarity of a multivariate periodic process is the (covariance) Stationarity of the “lumped” vector process which contains the periodic vectors as its elements. It is shown that for univariate and multivariate PARMA processes, even with periodically varying orders, the lumped process is a multivariate autoregressive moving average ARMA process, the Stationarity conditions of which are readily available. Periodic Stationarity conditions for the multivariate PARMA (1, 1) process are explicitly obtained, which apply for all PARMA (1, q) processes. It is shown that the periodic Stationarity of a periodic process always implies the Stationarity of the aggregated process, the sum of the periodic vectors. The reverse is yet to be proved or disproved. However, it is shown to be true for PAR(1) and PARMA (1, 1) processes.
Modeling of meltwater infiltration in subfreezing snow
Authors: Illangasekare Tissa H. , Walter Rodney J. , Meier Mark F. , Pfeffer W. Tad
Published: February 2008

A mathematical model which incorporates the processes that influence water flow and heat transfer in subfreezing snow was developed. Among the aspects of snow included are density and grain‐size heterogeneities, capillary‐pressure gradients, meltwater refreezing, time dependent hydraulic and thermal parameters, and heat conduction. From this conceptual mathematical model a numerical model of two‐dimensional meltwater infiltration was developed. Results from various test cases show which data are most important to measure accurately in the field, in order to determine how the snowpack will respond to an introduction of meltwater. These simulations also show the importance of the orientation of the various layers which make up the snowpack and how randomly distributed heterogeneities can produce two‐dimensional flow of meltwater under unsaturated conditions. Finally, it is demonstrated that various assumptions related to density and porosity variations, dimensionality of flow, capillary effects, etc., which have been made by past investigators for ideal situations may not be valid under many circumstances, and several suggestions are made for improving predictions of meltwater behavior. Sensitivity analysis showed that the model is most sensitive to changes in bulk density, residual saturation of wet snow and meltwater supply rates, whereas changes in snow temperature and mean grain size had less marked effect.
Fractal processes in soil water retention
Authors: Tyler Scott W. , Wheatcraft Stephen W.
Published: February 2008

Numerous empirical models exist for soil water retention and unsaturated hydraulic conductivity data. It has generally been recognized that the empirical fitting coefficients in these models are somehow related to soil texture. However, the fact that they are empirical means that elaborate laboratory experiments must be performed for each soil to obtain values for the parameters. Moreover, empirical models do not shed insight into the fundamental physical principles that govern the processes of unsaturated flow and drainage. We propose a physical conceptual model for soil texture and pore structure that is based on the concept of fractal geometry. The motivation for a fractal model of soil texture is that some particle size distributions in granular soils have already been shown to display self‐similar scaling that is typical of fractal objects. Hence it is reasonable to expect that pore size distributions may also display fractal scaling properties. The paradigm that we use for the soil pore size distribution is the Sierpinski carpet, which is a fractal that contains self similar “holes” (or pores) over a wide range of scales. We evaluate the water retention properties of regular and random Sierpinski carpets and relate these properties directly to the Brooks and Corey (or Campbell) empirical water retention model. We relate the water retention curves directly to the fractal dimension of the Sierpinski carpet and show that the fractal dimension strongly controls the water retention properties of the Sierpinski carpet “soil”. Higher fractal dimensions are shown to mimic clay‐type soils, with very slow dewatering characteristics and relatively low fractal dimensions are shown to mimic a sandy soil with relatively rapid dewatering characteristics. Our fractal model of soil water retention removes the empirical fitting parameters from the soil water retention models and provides parameters (fractal dimension) which are intrinsic to the nature of the fractal porous structure. The relative permeability functions of Burdine and Mualem are also shown to be fractal directly from fractal water retention results.
Snowmelt runoff modeling in a balsam fir forest with a variable source area simulator (VSAS2)
Authors: Prévost Marcel , Barry Richard , Stein Jean , Plamondon André P.
Published: February 2008

The variable source area model of storm flow generation VSAS2 has been adapted to simulate snowmelt runoff in the Lac Laflamme forested basin, 80 km north of Quebec City. The model has been adapted to accept different water inputs according to topography, to factor the effect of lake water storage in the discharge hydrograph and to process 3 months of hourly data. To ensure convergence of the mathematical solution, the explicit form of flow equations included in VSAS2 has been transformed to use an iterative approach. Lysimeter measurements as well as outputs from the snowmelt temperature index model SNOW‐17 were used as input data in the simulation. Results showed that low flows in early spring were well reproduced by the physically based model. However, all seasonal (1985, 1986 and 1987) peak flows were underestimated when all water input was considered to infiltrate. Observations on the site showed that the natural topographical drainage network was augmented in the spring by superficial concrete frost, pipe throughflow at the organic‐mineral soil interface and snowpack basal ice layers. It was therefore necessary to use an infiltrability index to improve the model. Because it was closely related to the development of an impervious layer at the soil surface, the relative proportion of bare ground areas on the basin was also related to the rising of streamflow hydrographs. Thus values of snow cover areal extent were taken from SNOW‐17 outputs and used as an index to the prevailing conditions of soil infiltrability on the basin. Results from VS AS2 were greatly improved, supporting the hypothesis of an important surface flow contribution during late snowmelt. The study underlined the necessity of further field investigations on the dynamics of infiltration processes into frozen soil.
Application of a snow cover energy and mass balance model in a balsam fir forest
Authors: Barry Richard , Prévost Marcel , Stein Jean , Plamondon Andre P.
Published: February 2008

The objective of this study was to adjust the parameters of the point energy and mass balance model of a snow cover developed by E. Anderson in 1976 when applied to a balsam fir forest. This physically based model was used to simulate the snow cover energy and mass balance during spring at Lac Laflamme (47°N, 71°W). The calibration of the model was done with the physical properties of snow and hourly outflow observed at a snow lysimeter in 1985 and 1986; the validation was performed with the 1987 data. For the three seasons simulated, the model yielded accurate predictions, particularly of hourly and daily outflows. As expected, the forest canopy limits latent and sensible heat transfers to the snow cover because of its effect on wind speed. The prediction of outflow was almost insensitive to variations to the roughness parameter and to the critical Richardson number but was moderately sensitive to most parameters related to liquid water retention and transmission. Lack of fit between predicted and observed outflows, densities and temperatures at various levels in the snowpack occurred when ice layers or ice lenses were suspected to be present in the snow.
Fuzzy regression in hydrology
Authors: Bardossy Andras , Bogardi Istvan , Duckstein Lucien
Published: February 2008

A general methodology for fuzzy regression is developed and illustrated by an actual hydrological case study. Fuzzy regression may be used whenever a relationship between variables is imprecise and/or data are inaccurate and/or sample sizes are insufficient. In such cases fuzzy regression may be used as a complement or an alternative to statistical regression analysis. In fuzzy regression, several “goodness of fit” criteria may be used such as the maximum average vagueness criterion and the prediction vagueness criterion. The technique is illustrated by means of a case study involving the relationship between soil electrical resistivity and hydraulic permeability. This relationship is imprecise and based on only a few data points. In the present case a curvilinear relationship is fitted using fuzzy regression with six calculated resistivities and six measured permeabilities. Prediction vagueness criteria appears to yield a more robust fuzzy regression than the maximum average vagueness criteria. Potential application areas of fuzzy regression in hydrology are discussed further. The methodology is relatively simple, and the results can be interpreted to provide a valuable hydrological decision‐making aid.
An assessment of a conceptual rainfall‐runoff model's ability to represent the dynamics of small hypothetical catchments: 2. Hydrologic responses for normal and extreme rainfall
Authors: Gan Thian Yew , Burges Stephen J.
Published: February 2008

Results from five numerical experiments to test a conceptual rainfall‐runoff model (the soil moisture accounting component, SMA, used by the U.S. National Weather Service), comprising combinations of three sets of input data (hourly precipitation and evapotranspiration data) and four hypothetical two‐layered small catchments (areas ≤0.2 km2, saturated hydraulic conductivity from 0.02 to 0.2 m/h, soil depth from 0.8 to 1.6 m, hillslope length from 100 to 250 m, and slope from 0.04 to 0.10), representing a wide range of flow mechanisms, are presented. The calibrated SMA model could simulate flow volumes corresponding to broad‐scale flow mechanisms but generally performed poorly during dry to wet catchment transitions. SMA was found to be unreliable in forecasting extreme floods, especially under dry antecedent moisture conditions, and for catchments where calibration data were comprised primarily of base flow. For each case, the sum of the SMA conceptual storages differed from the maximum physical water storage capacity of the hypothetical small catchment. The calibrated SMA model parameters were climate dependent indicating that a calibrated SMA model should be used with caution when predicting hydrologic response to a changed climate.
A new method to determine regional evapotranspiration
Authors: Magaritz Mordeckai , Kaufman Aaron , Paul Michael , Boaretto Elisabetta , Hollos George
Published: February 2008

A method is described whereby the chloride concentration and the ratio of 36Cl to total chloride of a given water body are compared with those of precipitation to determine the fraction of the original precipitation which was lost by evapotranspiration before it reached that water body. This method was applied to 11 water sources in the upper Jordan River basin, and the evapotranspirative loss was generally found to be in the range 40–90%. This method, which is much simpler than the other methods for determining regional evapotranspiration, will enable us to monitor the changes in the hydrological cycle which are expected to result from the greenhouse effect.
Similarity and length scale for spatially varied overland flow
Authors: Julien Pierre Y. , Moglen Glenn E.
Published: February 2008

One‐dimensional finite element models enable physically based investigations of overland flow generated under spatially varied surface slope, width, roughness, and excess rainfall intensity. Simulated results of 8400 dimensionless hydrographs under spatially varied input parameters indicate that runoff discharge variations depend primarily on the ratio of rainfall duration tr to the time to equilibrium te. Peak discharge distributions change drastically as the dimensionless rainfall duration tr/te approaches unity. Similarity conditions exist for all four parameters regardless of whether the spatial variability is correlated or uncorrelated. A length scale function of not only the spatially averaged values of surface parameters but also depending on rainstorm duration and intensity delineates similarity conditions for spatially varied surface runoff. For surface runoff lengths much shorter than this length scale, the rainfall‐runoff relationship becomes nearly independent of the spatial variability in hydrologic parameters. Conversely, for surface runoff lengths exceeding the length scale, the rainfall‐runoff relationship is sensitive to spatial variability. This length scale can serve as a basis for the determination of grid sizes in hydrologic models.
Water Resources Research and interdisciplinary hydrology
Authors: Freeze R. Allan
Published: February 2008

Water Resource Research was born under the watchful eye of Walter Langbein, a modern‐day Renaissance man whose interests spanned not only hydrology but all of the earth sciences, and not only the earth sciences but all of science. From its founding in1965 to the present day, the editors of WRR have always seen the journal as a medium of interdisciplinary interaction. On this 25th anniversary of WRR, I thought it might be worthwhile to look back on the interdisciplinary successes and failures of the past quarter decade, in our journal and in our science.

There is no question that research in water resources is an interdisciplinary endeavor. At my university we have a graduate program in interdisciplinary hydrology on the books, and on those occasions when we gather together, there are students and faculty there from as many as seven different departments: geography, geology, soil science, forestry, civil engineering, mining engineering, and bioresource engineering. In addition, our campus hosts the Westwater Research Institute where physical scientists can get involved in interdisciplinary research with social scientists from regional and community planning, resource management, resource economics, commerce, and law. I suspect that many campuses have a similar breadth of water resources interests. It is this breadth that WRR is designed to serve.
Interbed storage changes and compaction in models of regional groundwater flow
Authors: Leake S. A.
Published: February 2008

Water released from permanent compaction of compressible fine‐grained interbeds within confined aquifers may be a significant source of pumped water. Permanent or inelastic compaction of the interbeds occurs when head declines from pumping cause the effective stress or grain‐to‐grain load to exceed the elastic limits of the interbeds. As a result, the grains in the interbeds rearrange and excess water is expelled. The amount of inelastic compaction generally is proportional to the increase in effective stress and the decrease in head. A common approach for the simulation of elastic and inelastic compaction in groundwater flow models is to assume that head changes in the aquifer result in instantaneous storage changes in the compressible interbeds. A term is added to the groundwater flow equation to account for the storage changes. Changes in specific storage may be computed explicitly from the results at the previous time step in the finite difference formulation of the groundwater flow equation. A better approach is to implicitly apportion storage changes between elastic and inelastic components within a time step. If storage changes cannot be considered to occur instantaneously with change in head in the aquifer, another approach is taken. Equations for horizontal flow in the aquifer are coupled with equations for vertical flow in the compressible interbeds to simulate flow in half a representative doubly draining interbed. Storage changes and compaction are calculated for the representative half thickness and are extrapolated to the entire thickness of all interbeds within each cell. This approach was applied to an existing model of groundwater flow in the Central Valley of California. The simulation demonstrates that solving coupled systems of equations is feasible for a regional flow model.
The momentary instability of a saturated porous layer with a time‐dependent temperature distribution, and the most unstable disturbance
Authors: Green Theodore
Published: February 2008

The stability of fluid with a time‐dependent vertical temperature distribution in a horizontal, saturated porous layer is investigated, using the idea of momentary stability and a Galerkin technique. The most unstable disturbance is found by minimizing the critical Rayleigh number over the Fourier amplitudes of that disturbance, using both an iterative and a simplex procedure. As an example, the case in which an originally linear, stable temperature distribution is changed by lowering the temperature of the upper boundary at a constant rate is examined in detail.
An analytical solution for one‐dimensional transport in heterogeneous porous media
Authors: Yates S. R.
Published: February 2008

An analytical solution for describing the transport of dissolved substances in heterogeneous porous media with a distance‐dependent dispersion relationship has been developed. The analytical solution can be used to characterize differences in the transport process relative to the classical convection‐dispersion equation which assumes that the hydrodynamic dispersion in the porous medium remains constant. The form of the hydrodynamic dispersion function used in the analytical solution is
, where α(x) is the distance‐dependent dispersivity and
is the average pore water velocity. It is shown that for models which differ only in how the dispersion function is expressed, erroneous model parameters may result from parameter estimation techniques which assume a constant hydrodynamic dispersion coefficient if the porous medium is more accurately characterized by a distance‐dependent dispersion relationship. For such situations, the proposed model could be used to provide an alternate means for obtaining these parameters. The overall features of the solution are illustrated by several examples for constant concentration and flux boundary conditions.
Simulation of lake evaporation with application to modeling lake level variations of Harney‐Malheur Lake, Oregon
Authors: Hostetler S. W. , Bartlein P. J.
Published: February 2008

A physically based eddy diffusion model for simulating the seasonal variation in lake temperature and evaporation is presented and validated. Because no lake‐specific fitting of the parameters of the model is necessary, the model can be used to simulate evaporation in studies of climate change and lake hydrology in a variety of settings. The eddy diffusion model is used to simulate evaporation for input to a simple lake level model that is applied to reconstruct recent fluctuations in the level of Harney‐Malheur Lake caused by climatic variations.
Solution of the Transport Equation by the Collocation Method in Conjunction With the Adaptive Hermite Element Family
Authors: Bhuiyan Muhammed A. , Allayla Rashid I. , Hussain Tahir , Ishaq Achi M. , Mohsen M. F. N.
Published: February 2008

The solution of the advection‐dominated transport equation exhibits behavior whose structure is localized in small subregions of the spatial domain. This requires placing a high‐resolution spatial grid in their vicinity. In an attempt to increase the spatial resolution, a family of 16 adaptive Hermite elements has been developed. Collocation methodology in conjunction with these adaptive families produces a matrix whose bandwidth is larger than using cubic Hermite elements all over the solution domain. A special technique is devised to condense out this bandwidth prior to the solution of the global system. The numerical solutions are tested against the available one‐ and two‐dimensional analytical solutions. For the discretization attempted, the code was tested up to a Peclet number of 600 in one dimension and 200 in two dimensions.
Absorption of Water Into Porous Blocks of Various Shapes and Sizes
Authors: Zimmerman Robert W. , Bodvarsson Gudmundur S. , Kwicklis Edward M.
Published: February 2008

Approximate solutions are presented for absorption of water into porous spherical, cylindrical, and slablike blocks whose characteristic curves are of the van Genuchten‐Mualem type. The solutions are compared to numerical simulations of absorption into blocks of the Topopah Spring member (Paintbrush tuff) from the site of the proposed nuclear waste repository at Yucca Mountain, Nevada. Guided by these results, a scaling law, based on the ratio of surface area to volume, is then proposed for predicting the rate of absorption into irregularly shaped blocks. This scaling law is tested against a numerical simulation of absorption into an irregularly shaped, 2‐dimensional polygonal block and is shown to be a good approximation.
Importance of Air Absorption During Mechanical Integrity Testing
Authors: Arnold Fredric C.
Published: February 2008

Wells used for injection of liquid industrial waste into deep saline aquifers are required to be periodically tested for mechanical integrity. A generally accepted method to demonstrate mechanical integrity is to pressurize the casing‐tubing annulus and monitor any decline in pressure. If air is used to pressurize the annulus, uncertainty may exist in differentiating between absorption of air into water in the annulus and loss of pressure due to the absence of mechanical integrity. An analytical model of air absorbance has been derived and used to quantify the pressure decline due to dissolving and diffusion of the air in annular water. A parameteric study was made to determine when annular pressure decline due to absorption of air is significant.
A Triangular Finite Volume Approach With High‐Resolution Upwind Terms for the Solution of Groundwater Transport Equations
Authors: Putti Mario , Yeh William W.‐G. , Mulder William A.
Published: February 2008

A finite volume approach is developed for the solution of the contaminant transport equation in groundwater. By defining a triangular control volume over which the dependent variable of the governing equation is averaged, the scheme combines the flexibility in handling complex geometries intrinsic to finite element methods with the simplicity of finite difference techniques. High‐resolution upwind schemes are employed for the discretization of the advective terms. The technique is based on the concept of “monotone interpolation” to ensure the monotonicity preserving property of the scheme, and on the exact solution of local Riemann problems at the interface between neighboring control volumes. In this way, numerical oscillations are completely avoided for a full range of cell Peclet numbers. Together with the discretization of the dispersive fluxes, an approximation is obtained that is locally first order, but globally of second‐order accuracy. As compared to usual upwind schemes, much smaller amounts of numerical viscosity are introduced when sharp concentration fronts occur. A number of numerical tests show good agreement with analytical solutions. A hypothetical problem involving nonequilibrium reaction terms is solved to illustrate the applicability and robustness of the proposed formulation for solving the groundwater transport equations.
Streamflow Generation Processes: An Austral View
Authors: Pearce Andrew J.
Published: February 2008

Developments over the past 15 years in our understanding of streamflow generation processes are reviewed. Examples from small‐ and intermediate‐sized catchments in a wide range of hydrogeologic, climatic, and vegetative environments in New Zealand and northeastern Australia are used to illustrate the development and present state of knowledge. Increasingly detailed studies of small catchments and of hillslope and valley bottom segments have revealed increasingly complex and variable responses both in time and space. Although these studies have greatly increased conceptual understanding of flow generation, there has not yet been a corresponding increase in ability to model or predict flow processes. Further progress will require integration of field studies with chemical, physical, and mathematical model studies of specific processes to test hypotheses derived from previous work at well‐documented field sites. Concentration of the necessary skills and studies at a few intensively studied locations is also required, but this will impose new and difficult challenges for cooperation among specialists, research organizations, and funding sources.
Molecule fragmentation at the Dresden EBIS-A
Authors: Kreller M. , Zschornack G. , Kentsch U. , Heller R.
Published: February 2008

We report on molecule fragmentation measurements of propane in high dense electron beams of a room-temperature electron beam ion source, the so-called Dresden EBIS-A. After fragmentation of propane molecules in the electron beam the fragments were continuously extracted and q∕A separated by a bifocal dipole magnet. Fragmentation spectra were measured at working gas pressures of 10−9mbar up to 10−8mbar, electron currents of 29mA up to 75mA, and electron energies of 11keV up to 15keV. Thereby all possible stoichiometric ratios of propane fragments were detected. At low electron beam currents the ion current output of the CHx+ (x=0–3) and the C2Hx+ (x=0–5) fragments is nearly identically. At higher electron currents the CHx+ (x=0–3) peaks dominate the spectra and the ratio between the C+ peak and CHx+ (x=0–3) peaks increases from 2:1 to 3:1. It was shown that the working gas pressure has no significant influence on the fragment distribution but on the total ion current.
Compact electron beam ion sources/traps: Review and prospects (invited)
Authors: Zschornack G. , Kreller M. , Ovsyannikov V. P. , Grossman F. , Kentsch U. , Schmidt M. , Ullmann F. , Heller R.
Published: February 2008

The Dresden electron beam ion trap (EBIT)/electron beam ion source (EBIS) family are very compact and economically working table-top ion sources. We report on the development of three generations of such ion sources, the so-called Dresden EBIT, Dresden EBIS, and Dresden EBIS-A, respectively. The ion sources are classified by different currents of extractable ions at different charge states and by the x-ray spectra emitted by the ions inside the electron beam. We present examples of x-ray measurements and measured ion currents extracted from the ion sources at certain individual operating conditions. Ion charge states of up to Xe48+ but also bare nuclei of lighter elements up to nickel have been extracted. The application potential of the ion sources is demonstrated via proof-of-concept applications employing an EBIT in a focused ion beam (FIB) column or using an EBIT for the production of nanostructures by single ion hits. Additionally we give first information about the next generation of the Dresden EBIS series. The so-called Dresden EBIS-SC is a compact and cryogen-free superconducting high-B-field EBIS for high-current operation.
Fluctuation effects and the stability of the Fddd network phase in diblock copolymer melts
Authors: Miao Bing , Wickham Robert A.
Published: February 2008

We examine the effect of composition fluctuations on the stability of the orthorhombic Fddd network phase in the diblock copolymer melt phase diagram within the self-consistent Hartree approximation to the Landau-Brazovskii theory. For weak fluctuations, the Fddd structure is an equilibrium phase; however, stronger fluctuations render this phase metastable. These results suggest a reinterpretation of a recent experiment beyond mean-field theory. Fluctuations may also explain why an equilibrium Fddd phase is not generally observed in analogous self-assembling systems.
Giant positive magnetoresistance in Fe doped In2O3 and InREO3 (RE=Eu,Nd) composites
Authors: Peleckis G. , Wang X. L. , Dou S. X. , Munroe P. , Ding J. , Lee B.
Published: February 2008

Synthesis and characterization of Fe and rare earth (RE) (RE=Eu,Nd) codoped bulk In2O3 oxide are reported. Composites consisting of Fe-doped In2O3 and InREO3 phases were formed, as determined by x-ray diffraction and transmission electron microscopy, with particle sizes of 50–120nm. The composites exhibit superparamagnetic and semiconducting behavior. A giant positive magnetoresistance is observed at low temperatures, reaching 81% and 50% at 5K in Eu–Fe and Nd–Fe codoped samples, respectively.
Ultraviolet bandpass Al0.17Ga0.83N∕GaN heterojunction phototransitors with high optical gain and high rejection ratio
Authors: Lee M. L. , Sheu J. K. , Shu Yung-Ru
Published: February 2008

Ultraviolet Al0.17Ga0.83N∕GaN-based heterojunction phototransistors (HPTs) grown by metal-organic vapor-phase epitaxy were demonstrated. The HPTs showed a bandpass spectral responsivity ranging from 280to390nm. With a bias voltage of 6V, the responsivity at an incident of 340nm was as high as 1500A∕W, corresponding to a quantum gain of 5.47×103. In contrast to GaN-based photoconductors, the HPTs also featured high contrast in spectral response. With a bias voltage of 3V, the spectral response showed high rejection ratios of approximately 4×105 and 1×104 for the long-wavelength side (340∕400nm) and the short-wavelength side, respectively. The high contrast of spectral response for the long-wavelength side could be due to the long trapping time of holes blocked by the base-emitter heterojunction and the low defect-to-band response that is caused by defect-related gap states.
Organic semiconductor-carbon nanotube bundle bilayer field effect transistors with enhanced mobilities and high on/off ratios
Authors: Liu Shuhong , Mannsfeld Stefan C. B. , LeMieux Melbs C. , Lee Hang W. , Bao Zhenan
Published: February 2008

Organic field-effect transistors containing pentacene or α sexithiophene on random arrays of carbon nanotube bundles were fabricated. The impact of nanotube bundles on the performance of devices with different geometries and surface treatments was studied. Upon incorporation of an appropriate amount of nanotube bundles, we observed an increase in the “effective” field effect mobility as high as 20 times while maintaining the high on/off ratios. Furthermore, our preliminary results show that nanotube bundles might template the growth of organic crystals under certain conditions, resulting in the formation of organic nucleates with preferred orientations.
Computational Models of Facial Attractiveness Judgments
Authors: Bronstad P Matthew , Langlois Judith H , Russell Richard
Published: February 2008

We designed two computational models to replicate human facial attractiveness ratings. The primary model used partial least squares (PLS) to identify image factors associated with facial attractiveness from facial images and attractiveness ratings of those images. For comparison we also made a model similar to previous models of facial attractiveness, in that it used manually derived measurements between features as inputs, though we took the additional step of dimensionality reduction via principal component analysis (PCA) and weighting of PCA dimensions via a perceptron. Strikingly, both models produced estimates of facial attractiveness that were indistinguishable from human ratings. Because PLS extracts a small number of image factors from the facial images that covary with attractiveness ratings of the images, it is possible to determine the information used by the model. The image factors that the model discovered correspond to two of the main contemporary hypotheses of averageness judgments: facial attractiveness and sexual dimorphism. In contrast, facial symmetry was not important to the model, and an explicit feature-based measurement of symmetry was not correlated with human judgments of facial attractiveness. This provides novel evidence for the importance of averageness and sexual dimorphism, but not symmetry, in human judgments of facial attractiveness.
Quiet Influences, Big Consequences: An Interview with Carol A. Pilgrim
Authors: Epting L. Kimberly
Published: February 2008

Carol Pilgrim received her PhD from the University of Florida in 1987 with a specialization in the experimental analysis of behavior. She is currently Professor of Psychology and Associate Dean of the College of Arts and Sciences at the University of North Carolina—Wilmington. She has been honored with a Distinguished Teaching Professorship, the North Carolina Board of Governors Teaching Excellence Award, the Faculty Scholarship Award, the Chancellor's Teaching Excellence Award, and the College of Arts and Sciences Excellence in Teaching Award. Her research centers on both basic and applied behavior analysis, with an emphasis in human operant behavior, relational stimulus control, and the early detection of breast cancer. She has served as editor of The Behavior Analyst, associate editor of the Journal of the Experimental Analysis of Behavior and of The Behavior Analyst, co-editor of the Experimental Analysis of Human Behavior Bulletin, and as a member of the editorial boards of those and several other journals. She has served as President of the Association for Behavior Analysis, the Society for the Advancement of Behavior Analysis International, Division 25 of the American Psychological Association, and the Southeastern Association for Behavior Analysis. She is also a member of the Board of Directors of the Cambridge Center for Behavioral Studies. Dr. Pilgrim teaches Behavior Analysis; Psychology of Learning with an animal lab; Applied Behavior Analysis; General Psychology; and special seminars on stimulus control, concept learning, category formation, small-n research design, and conceptual issues in behavior analysis.

L. Kimberly Epting currently is Assistant Professor of Psychology at Elon University in North Carolina. Kim received a Master's degree under the direction of Carol Pilgrim at the University of North Carolina—Wilmington before going on to complete her doctoral work in experimental psychology at Auburn University. At Elon University, she teaches a variety of courses including General Psychology, Learning and Memory, Cognitive Psychology, and Psychology of Language. Her research focuses on self-editing behavior in speech and writing.
Progesterone modulates aggression in sex-role reversed female African black coucals
Authors: Goymann Wolfgang , Wittenzellner Andrea , Schwabl Ingrid , Makomba Musa
Published: February 2008

Testosterone is assumed to be the key hormone related to resource-defence aggression. While this role has been confirmed mostly in the context of reproduction in male vertebrates, the effect of testosterone on the expression of resource-defence aggression in female vertebrates is not so well established. Furthermore, laboratory work suggests that progesterone inhibits aggressive behaviour in females. In this study, we investigated the hormonal changes underlying territorial aggression in free-living female African black coucals,
Centropus grillii
(Aves; Cuculidae). Females of this sex-role reversed polyandrous bird species should be particularly prone to be affected by testosterone because they aggressively defend territories similar to males of other species. We show, however, that territorial aggression in female black coucals is modulated by progesterone. After aggressive territorial challenges female black coucals expressed lower levels of progesterone than unchallenged territorial females and females without territories, suggesting that progesterone may suppress territorial aggression and is downregulated during aggressive encounters. Indeed, females treated with physiological concentrations of progesterone were less aggressive than females with placebo implants. This is one of the first demonstrations of a corresponding hormone–behaviour interaction under challenged and experimental conditions in free-living females. We anticipate that our observation in a sex-role reversed species may provide a more general mechanism, by which progesterone—in interaction with testosterone—may regulate resource-defence aggression in female vertebrates.
TheArabidopsisPhytochrome-Interacting Factor PIF7, Together with PIF3 and PIF4, Regulates Responses to Prolonged Red Light by Modulating phyB Levels
Authors: Leivar Pablo , Monte Elena , Al-Sady Bassem , Carle Christine , Storer Alyssa , Alonso Jose M. , Ecker Joseph R. , Quail Peter H.
Published: February 2008

We show that a previously uncharacterized Arabidopsis thaliana basic helix-loop-helix (bHLH) phytochrome interacting factor (PIF), designated PIF7, interacts specifically with the far-red light–absorbing Pfr form of phyB through a conserved domain called the active phyB binding motif. Similar to PIF3, upon light exposure, PIF7 rapidly migrates to intranuclear speckles, where it colocalizes with phyB. However, in striking contrast to PIF3, this process is not accompanied by detectable light-induced phosphorylation or degradation of PIF7, suggesting that the consequences of interaction with photoactivated phyB may differ among PIFs. Nevertheless, PIF7 acts similarly to PIF3 in prolonged red light as a weak negative regulator of phyB-mediated seedling deetiolation. Examination of pif3, pif4, and pif7 double mutant combinations shows that their moderate hypersensitivity to extended red light is additive. We provide evidence that the mechanism by which these PIFs operate on the phyB signaling pathway under prolonged red light is through maintaining low phyB protein levels, in an additive or synergistic manner, via a process likely involving the proteasome pathway. These data suggest that the role of these phyB-interacting bHLH factors in modulating seedling deetiolation in prolonged red light may not be as phy-activated signaling intermediates, as proposed previously, but as direct modulators of the abundance of the photoreceptor.
An Inositol Polyphosphate 5-Phosphatase Functions in PHOTOTROPIN1 Signaling in Arabidopis by Altering Cytosolic Ca2+
Authors: Chen Xu , Lin Wen-Hui , Wang Yuan , Luan Sheng , Xue Hong-Wei
Published: February 2008

Inositol polyphosphate 5-phosphatase (5PTase) is a key enzyme in the phosphatidylinositol metabolic pathway, which plays critical roles in a number of cellular processes in plants. Our previous work implicated the role of 5PTase13, which encodes a WD40-containing type II 5PTase, in hormone-mediated cotyledon vein development. Here, we show that 5PTase13 is also involved in blue light responses in Arabidopsis  thaliana. Compared with that in darkness, the expression of 5PTase13 was suppressed by blue light irradiation, and disruption of the gene resulted in shortened hypocotyls and expanded cotyledons. Genetic analysis showed that 5PTase13 acted independently from CRYPTOCHROME1 and CONSTITUTIVE PHOTOMORPHOGENIC1 but interacted functionally with PHOTOTROPIN1 (PHOT1). The expression level of 5PTase13 was significantly enhanced in phot1 single or phot1 phot2 double mutants under blue light, and suppression of 5PTase13 expression rescued the elongated hypocotyls in the phot1 or phot1 phot2 mutants. Further analysis showed that the blue light–induced elevation of cytosolic Ca2+ was inhibited in the phot1 mutant but enhanced in the 5pt13 mutant, suggesting that 5PTase13 antagonizes PHOT1-mediated effects on calcium signaling under blue light.
Effects of tag and suture type on survival and growth of brown trout with surgically implanted telemetry tags in the wild
Authors: Jepsen N. , Mikkelsen J. S. , Koed A.
Published: February 2008

To test the effects of surgical implants with or without external antennae, 188 wild brown trout Salmo trutta, 150–290 mm, were tagged and released in a small river in May 2005. After 5 months, 103 of the fish were recaptured and examined. Thus, information on the relative survival, growth and general condition of each fish was obtained. The relative survival did not differ between the three groups (control, antennae and no antennae), but the specific growth of the two tagged groups were lower than that of the control fish. The tag:body‐mass ratio had a significant negative effect on specific growth. A relative high occurrence of tag expulsion was observed in both treatment groups (23%). The probability to expel a tag was correlated with the tag:body‐mass ratio. Finally, the relative survival, growth, expulsion rate and general condition were compared between fish tagged with different types of suture material (absorbable v. non‐absorbable). The results show only minor differences, but absorbable suture provided better wound healing and fewer expulsions.
Variation in behavioural response to oxygen stress by egg‐tending males of parapatric fluvial and lacustrine populations of a landlocked goby
Authors: Maruyama A. , Onoda Y. , Yuma M.
Published: February 2008

The behavioural response of egg‐tending males from parapatric fluvial and lacustrine populations of a landlocked goby Rhinogobius sp. (the orange form) to oxygen stress was compared in laboratory experiments. The natural spawning locations of these populations (rapids of tributary rivers and lakeshore of Lake Biwa, respectively) differ in dissolved oxygen concentration and its variability. Males of both populations spent a longer period of time in fanning behaviour under low dissolved oxygen conditions (4·5–5·0 mg l−1), where >90% of eggs without paternal care died before reaching eyed stage, relative to fully saturated dissolved oxygen conditions (8·0–8·5 mg l−1). Lacustrine males, who occasionally encounter oxygen stress (<2 mg l−1) in their natural habitat, fanned eggs for a longer time period than fluvial males. The time difference in fanning behaviour between the two oxygen conditions was greater for lacustrine than fluvial males. Survival rate in the lower oxygen condition was higher for eggs tended by lacustrine males than those tended by fluvial males, probably due to this difference in fanning activity. These results showed that the response to oxygen stress differs between the two populations and, moreover, as both populations behaved adaptively in responding to the reduction in dissolved oxygen, contiguous habitats may have distinct natural selective pressures. It is suggested that regulation of egg fanning activity is strongly favoured by natural selection in unpredictable environments.
Histone deacetylase inhibitors trichostatin A and valproic acid circumvent apoptosis in human leukemic cells expressing the RUNX1 chimera
Authors: Sasaki Ko , Yamagata Tetsuya , Mitani Kinuko
Published: February 2008

Disturbance of the normal functions of wild‐type RUNX1 resulting from chromosomal translocations or gene mutations is one of the major molecular mechanisms in human leukemogenesis. RUNX1‐related chimeras generated by the chromosomal translocations repress transcriptional activity of wild‐type RUNX1 by recruiting the co‐repressor/histone deacetylase complex. Thus, histone deacetylase inhibitors are expected to restore normal functions of wild‐type RUNX1 and thereby affect the growth and differentiation ability of leukemic cells expressing the chimera. We investigated the in vitro effects of histone deacetylase inhibitors, trichostatin A and valproic acid, on human leukemic cell lines such as SKNO‐1 and Kasumi‐1 expressing RUNX1/ETO, Reh expressing TEL/RUNX1 and SKH‐1 co‐expressing RUNX1/EVI1 and BCR/ABL. We also employed K562 cells expressing BCR/ABL without such a chimera as a control. Treatment with each inhibitor increased acetylated histone 4 in all of these cell lines. Interestingly, proliferation of SKNO‐1, Kasumi‐1, SKH‐1 and Reh cells was significantly suppressed after 3‐day culture with trichostatin A or valproic acid, when compared to that of K562 cells. We observed cell cycle arrest and apoptotic induction in the RUNX1 chimera‐expressing cells by the propidium iodide staining. Up‐ and downregulation of cell cycle regulator genes appeared to be the molecular basis for the former, and activation of both extrinsic and intrinsic apoptotic caspases for the latter. We propose histone deacetylase inhibitors to be an attractive choice in the molecular targeting therapy of RUNX1‐related leukemia. (Cancer Sci 2008; 99: 414–422)
Radioimmunotherapy of human synovial sarcoma using a monoclonal antibody against FZD10
Authors: Fukukawa Chikako , Hanaoka Hirofumi , Nagayama Satoshi , Tsunoda Tatsuhiko , Toguchida Junya , Endo Keigo , Nakamura Yusuke , Katagiri Toyomasa
Published: February 2008

We previously reported Frizzled homolog 10 (FZD10), a member of the Frizzled family, to be a promising therapeutic target for synovial sarcomas. In this report, we established a murine monoclonal antibody (MAb), namely, MAb 92‐13 that had specific binding activity against native FZD10 product expressed in synovial sarcoma cell lines. Subsequent immunohistochemical analyses with the MAb 92‐13 confirmed an absence or hardly detectable level of FZD10 protein in any normal human organs. We confirmed the specific binding activity of this MAb in vivo after injection of fluorescent‐labeled MAb i.p. or i.v. into the mice carrying synovial sarcoma xenografts by the use of the in vivo fluorescent imaging system as well as radioisotopes. Moreover, MAb 92‐13 was effectively internalized into the synovial sarcoma cells after its binding to FZD10 on the cell surface. A single i.v. injection of the Yttrium‐90 (90Y)‐MAb 92‐13 drastically suppressed tumor growth of synovial sarcoma in mice without any severe toxicity. Median time to tumor progression was 58 days for mice treated with 90Y‐MAb 92‐13 and 9 days for mice treated with non‐labeled antibody control or untreated mice (difference = 49 days; P = 7 × 10−5). This result indicates that MAb 92‐13 could be utilized as the novel treatment modality for synovial sarcoma and other FZD10‐positive tumors. (Cancer Sci 2008; 99: 432–440)