ALBERT

Beschreibung: The water retention curve (θ(ψ)), which defines the relationship between soil volumetric water content (θ) and matric potential (ψ), is of paramount importance in characterizing the hydraulic behaviour of soils. However, few methods are so far available for estimating θ(ψ) in undisturbed soil samples. We present a new design of TDR-pressure cell (TDR-Cell) for estimating θ(ψ) in undisturbed soil samples. The TDR-Cell consists of a 50-mm-long and 50-mm internal diameter stainless steel cylinder (which constitutes the outer frame of a coaxial line) attached to a porous ceramic disc and closed at the ends with two aluminium lids. A 49-mm-long and 3-mm-diameter stainless steel rod, which runs longitudinally through the centre of the cylinder, constitutes the inner rod of a coaxial TDR probe. The TDR-Cell was used to determine the θ(ψ) curves of a packed sand and seven undisturbed soil samples from three profiles of agricultural soils. These θ(ψ) curves were subsequently compared to those obtained from the corresponding 2-mm sieved soils using the pressure plate method. Measurements of bulk electrical conductivity, σ a , as a function of the water content, σ a (θ), of the undisturbed soil samples were also performed. An excellent correlation (R 2 = 0.988) was found between the θ values measured by TDR on the different undisturbed soils and the corresponding θ obtained from the soil gravimetric water content. A typical bimodal θ(ψ) function was found for most of the undisturbed soil samples. Comparison between the θ(ψ) curves measured with the TDR-Cell and those obtained from the 2-mm sieved soils showed that the pressure plate method overestimates θ at low ψ values. The σ a (θ) relationship was well described by a simple power expression (R 2 〉 0.95), in which the power factor, defined as tortuosity, ranged between 1.18 and 3.75. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Snowfall is an important part of the yearly water balance for the Catskill Mountains in New York State, the location of water supply reservoirs for New York City. Recent studies have shown that the effects of climate change on the hydrology of the Catskills will most likely create (1) a decrease in the proportion of precipitation falling as snow, (2) a shift in the timing of snowmelt that will cause snowmelt-supplemented streamflow events to occur earlier in the fall and winter, and (3) a decrease in the magnitude of traditionally high April streamflow. The shift in timing of snowmelt-influenced streamflow events is measured by the winter-early spring centre of volume (WSCV), defined as the Julian Day on which half the total streamflow volume from January to May occurs. Studies of streamflow, precipitation, and temperature trends in the last 50 years have shown that the WSCV is already earlier by about 5–10 days. This study investigates the use of watershed-scale snowpack and snowmelt algorithms that are incorporated in two existing watershed water quality models, Generalized Watershed Loading Functions-Variable Source Area (GWLF-VSA) and Soil and Water Assessment Tool (SWAT), to capture the potential effects of climate change on the timing and magnitude of streamflow during the late fall, winter, and early spring for the Catskill Mountain region. The GWLF-VSA model reasonably simulated the recent shifts in the winter streamflow timing, with simulations over the previous 50-year period yielding shifts in WSCV of 2–15 days. The SWAT model yielded similar results as the GWLF-VSA simulations. Scenarios of potential climate change 100 years in the future showed a similar shift in direction of timing winter streamflow, but at a larger magnitude than observed to date with WSCV occurring 15–20 days earlier. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Jonathan D. Chisum, Erich N. Grossman, and Zoya Popovic This article describes the theory and design of an ultra-low noise electronic readout circuit for use with room temperature video-rate terahertz imaging arrays. First, the noise characteristics of various imaging detectors, including low resistance bolometers and high resistance diodes are discussed ... [Rev. Sci. Instrum. 82, 065106 (2011)] published Thu Jun 16, 2011.

Beschreibung: We use dissolved silicon together with its “geochemical twin” germanium for the first time as a hydrologic tracer to study water delivery to the stream during storm events in the Rio Icacos watershed, Puerto Rico. Ge and Si were measured on base flow, stormflow, springwater, and soil water samples. Compositions of all of these waters appear to reflect varying contributions from three components, which we attribute to solutes released from bedrock weathering (groundwater), from short-term soil-water interaction (quick soil water), and longer-term soil-water interaction (matrix soil water). Base flow stream waters have high Si and moderate Ge (Ge/Si ratio ∼0.29 μmol/mol), consistent with a predominantly bedrock weathering source as indicated by their similarity with water sampled from springs emerging from the saprolite-bedrock boundary on a hillslope landslide scar. During storm events there is a shift toward more dilute compositions (but higher Ge/Si ratios) similar to those measured on water samples from temporary depression storage and overland flow (quick soil water). Geochemical mass balance shows that 80%–90% of the stream chemistry can be explained by mixing groundwater with this quick soil water composition, which we infer to reflect new water traveling as shallow throughflow. Stream water δ18O values decrease to more negative values typical of precipitation supporting rapid delivery of rainwater to the stream channel during stormflow. The third component, with a Ge-rich composition characteristic of soil matrix water sampled by tension lysimeters, is required to explain higher stream water Ge/Si ratios measured during hydrograph recession. We infer from this an additional, slower, and less dominant pathway for delivery of soil water to the stream channel.

Beschreibung: We present a predictive, multiscale modeling framework for chemotaxis in porous media. This model results from volume averaging the governing equations for bacterial transport at the microscale and is expressed in terms of effective medium coefficients that are predicted from the solution of the associated closure problems. As a result, the averaged chemotactic velocity is an explicit function of the attractant concentration field and diffusivity, rather than an empirical effective chemotactic sensitivity coefficient. The model was validated by comparing the transverse bacterial concentration profiles with experimental measurements for Escherichia coli HCB1 in a T-sensor. The averaged chemotactic velocity predicted by the model was found to be within the range of values reported in the literature. Reasonable agreement (approximately 10% mean absolute error) between theory and experiments was found for several flow rates. In order to assess the potential for decreasing the computational demands of the model, the macroscale domain was divided into subdomains for the coupling of bacterial transport to that of the attractant. Sensitivity analysis was performed regarding the number of subdomains chosen, and the results indicate that bacterial transport (as measured by concentration profiles) was not highly affected by this choice. Overall, these results suggest that the predictive, multiscale modeling framework is reliable for modeling chemotaxis in porous media when chemotactic transport is significant compared to convective transport.

Beschreibung: Water temperature determines the spatial distribution of fish species, including cold-water fish such as trout, and is driven by the balance of the heat flux across the water surface and the heat flux across the sediment surface. In this study, a modified equilibrium temperature model was developed for cold-water streams that includes the effect of groundwater inflow. The modified equilibrium temperature model gives estimates of daily average stream temperature based on climate conditions, riparian shading, stream width, and groundwater input rate and temperature. For a small tributary stream with relatively uniform riparian shading, the modified equilibrium temperature was found to be a good predictor of daily average stream temperature, with a root-mean-square errors (RMSE) of 1.2°C. The modified equilibrium temperature model also gave good estimates (1.4°C RMSE) of daily average stream temperature for a larger stream when riparian shading was averaged over sufficiently long distances. A sensitivity analysis using the modified equilibrium temperature model confirmed that water temperature in cold-water streams varies strongly with riparian shading, stream width, and both groundwater inflow rate and temperature. These groundwater parameters therefore need to be taken into account when climate change impacts on stream temperature are projected. The stream temperature model developed in this study is a useful tool to characterize temperature conditions in cold-water streams with different levels of riparian shading and groundwater inputs and to assess the impact of future land use and climate change on temperature in these streams.

Beschreibung: Zahra Noroozi, Horacio Kido, Regis Peytavi, Rie Nakajima-Sasaki, Algimantas Jasinskas et al. A novel, centrifugal disk-based micro-total analysis system ([mu]TAS) for low cost and high throughput semi-automated immunoassay processing was developed. A key innovation in the disposable immunoassay disk design is in a fluidic structure that enables very efficient micro-mixing based on a recipro ... [Rev. Sci. Instrum. 82, 064303 (2011)] published Tue Jun 21, 2011.

Beschreibung: L. Helfen, A. Myagotin, P. Mikulik, P. Pernot, A. Voropaev et al. Hard x rays from a synchrotron source are used in this implementation of computed laminography for three-dimensional (3D) imaging of flat, laterally extended objects. Due to outstanding properties of synchrotron light, high spatial resolution down to the micrometer scale can be attained, even for sp ... [Rev. Sci. Instrum. 82, 063702 (2011)] published Tue Jun 21, 2011.

Beschreibung: Philipp Rahe, Jens Schutte, Werner Schniederberend, Michael Reichling, Masayuki Abe et al. The acquisition of dense 3D data sets is of great importance, but also a challenge for scanning probe microscopy (SPM). Thermal drift often induces severe distortions in the data, which usually constrains the acquisition of dense data sets to experiments under ultra-high vacuum and low-temperature c ... [Rev. Sci. Instrum. 82, 063704 (2011)] published Wed Jun 22, 2011.

Beschreibung: Y. W. Lai (黎耀威) , S. Hamann, M. Ehmann, and A. Ludwig We report the development of an advanced high-throughput stress characterization method for thin film materials libraries sputter-deposited on micro-machined cantilever arrays consisting of around 1500 cantilevers on 4-inch silicon-on-insulator wafers. A low-cost custom-designed digital holographic ... [Rev. Sci. Instrum. 82, 063903 (2011)] published Wed Jun 22, 2011.

Beschreibung: K. Watanabe, M. Dairaku, H. Tobari, M. Kashiwagi, T. Inoue et al. A plasma generator for a long pulse H/D ion source has been developed. The plasma generator was designed to produce 65 A H/D beams at an energy of 120 keV from an ion extraction area of 12 cm in width and 45 cm in length. Configuration of the plasma generator is a multi-cusp bucket type with SmCo pe ... [Rev. Sci. Instrum. 82, 063507 (2011)] published Thu Jun 23, 2011.

Beschreibung: W. A. Bongers, V. van Beveren, D. J. Thoen, P. J. W. M. Nuij, M. R. de Baar et al. An intermediate frequency (IF) band digitizing radiometer system in the 100200 GHz frequency range has been developed for Tokamak diagnostics and control, and other fields of research which require a high flexibility in frequency resolution combined with a large bandwidth and the retrieval of the fu ... [Rev. Sci. Instrum. 82, 063508 (2011)] published Fri Jun 24, 2011.

Beschreibung: E. de Rijk, A. Macor, J-Ph. Hogge, S. Alberti, and J-Ph. Ansermet We demonstrate the construction of corrugated waveguides using stacked rings to propagate terahertz frequencies. The waveguide allows propagation of the same fundamental mode as an optical-fiber, namely, the HE mode. This simple concept opens the way for corrugated wave-guides up to several terahert ... [Rev. Sci. Instrum. 82, 066102 (2011)] published Wed Jun 8, 2011.

Beschreibung: Y. J. Montagut, J. V. Garcia, Y. Jimenez, C. March, A. Montoya et al. The improvement of sensitivity in quartz crystal microbalance (QCM) applications has been addressed in the last decades by increasing the sensor fundamental frequency, following the increment of the frequency/mass sensitivity with the square of frequency predicted by Sauerbrey. However, this sensiti ... [Rev. Sci. Instrum. 82, 064702 (2011)] published Fri Jun 10, 2011.

Beschreibung: Scott N. Schiffres and Jonathan A. Malen A novel 3omega thermal conductivity measurement technique called metal-coated 3omega is introduced for use with liquids, gases, powders, and aerogels. This technique employs a micron-scale metal-coated glass fiber as a heater/thermometer that is suspended within the sample. Metal-coated 3omega excee ... [Rev. Sci. Instrum. 82, 064903 (2011)] published Fri Jun 10, 2011.

Beschreibung: Perfect or even mediocre weather predictions over a long period are almost impossible because of the ultimate growth of a small initial error into a significant one. Even though the sensitivity of initial conditions limits the predictability in chaotic systems, an ensemble of prediction from different possible initial conditions and also a prediction algorithm capable of resolving the fine structure of the chaotic attractor can reduce the prediction uncertainty to some extent. All of the traditional chaotic prediction methods in hydrology are based on single optimum initial condition local models which can model the sudden divergence of the trajectories with different local functions. Conceptually, global models are ineffective in modeling the highly unstable structure of the chaotic attractor. This paper focuses on an ensemble prediction approach by reconstructing the phase space using different combinations of chaotic parameters, i.e., embedding dimension and delay time to quantify the uncertainty in initial conditions. The ensemble approach is implemented through a local learning wavelet network model with a global feed-forward neural network structure for the phase space prediction of chaotic streamflow series. Quantification of uncertainties in future predictions are done by creating an ensemble of predictions with wavelet network using a range of plausible embedding dimensions and delay times. The ensemble approach is proved to be 50% more efficient than the single prediction for both local approximation and wavelet network approaches. The wavelet network approach has proved to be 30%–50% more superior to the local approximation approach. Compared to the traditional local approximation approach with single initial condition, the total predictive uncertainty in the streamflow is reduced when modeled with ensemble wavelet networks for different lead times. Localization property of wavelets, utilizing different dilation and translation parameters, helps in capturing most of the statistical properties of the observed data. The need for taking into account all plausible initial conditions and also bringing together the characteristics of both local and global approaches to model the unstable yet ordered chaotic attractor of a hydrologic series is clearly demonstrated.

Beschreibung: The focus in the search for more reliable predictions in ungauged basins (PUB) has generally been on reducing uncertainty in watershed models (mainly their parameters). More recently, however, we seem to remember that the ultimate objective is not to define the parameters of a specific model but to understand the watershed: What behavior do we expect the ungauged watershed to exhibit? And what behavior should not occur in a particular ungauged watershed? The answers to these questions actually provide additional information that can be assimilated in watershed models for uncertainty reduction in PUB. This extension to hydrologic modeling approaches provides a quantitative link between watershed modeling and statistical hydrology as well as process hydrology that has to be explored. We witness a convergence of approaches—Bayesian, set theoretic, and optimization based—toward utilizing this link. The result is an opportunity for the (quantitative) dialog between modelers, statistical hydrologists, and experimentalists. We close our discussion of this development by presenting new and exciting research questions that we now have to address.

Beschreibung: Concept development simulation with distributed, physics-based models provides a quantitative approach for investigating runoff generation processes across environmental conditions. Disparities within data sets employed to design and parameterize boundary value problems used in heuristic simulation inevitably introduce various levels of bias. The objective was to evaluate the impact of boundary value problem complexity on process representation for different runoff generation mechanisms. The comprehensive physics-based hydrologic response model InHM has been employed to generate base case simulations for four well-characterized catchments. The C3 and CB catchments are located within steep, forested environments dominated by subsurface stormflow; the TW and R5 catchments are located in gently sloping rangeland environments dominated by Dunne and Horton overland flows. Observational details are well captured within all four of the base case simulations, but the characterization of soil depth, permeability, rainfall intensity, and evapotranspiration differs for each. These differences are investigated through the conversion of each base case into a reduced case scenario, all sharing the same level of complexity. Evaluation of how individual boundary value problem characteristics impact simulated runoff generation processes is facilitated by quantitative analysis of integrated and distributed responses at high spatial and temporal resolution. Generally, the base case reduction causes moderate changes in discharge and runoff patterns, with the dominant process remaining unchanged. Moderate differences between the base and reduced cases highlight the importance of detailed field observations for parameterizing and evaluating physics-based models. Overall, similarities between the base and reduced cases indicate that the simpler boundary value problems may be useful for concept development simulation to investigate fundamental controls on the spectrum of runoff generation mechanisms.

Beschreibung: In semi-arid areas high-intensity rainfall events are often held responsible for the main part of soil erosion. Long-term landscape evolution models usually use average annual rainfall as input, making the evaluation of single events impossible. Event-based soil erosion models are better suited for this purpose, but cannot be used to simulate longer timescales and are usually applied to plots or small catchments. In this study, the openLISEM event-based erosion model was applied to the medium sized ( 50 km 2 ) Prado catchment in SE Spain. Our aim was to (i) test the model's performance for medium sized catchments; (ii) test the ability to simulate four selected typical Mediterranean rainfall events of different magnitude, and (iii) explore the relative contribution of these different storms to soil erosion using scenarios of future climate variability. Results show that due to large differences in the hydrologic response between storms of different magnitudes, each event needed to be calibrated separately. The relation between rainfall event characteristics and the calibration factors might help in determining optimal calibration values if event characteristics are known. Calibration of the model features some drawbacks for large catchments due to spatial variability in K sat values. Scenario calculations show that, although 50% of soil erosion occurs as a result of high frequency, low intensity rainfall events, large magnitude, low frequency events potentially contribute significantly to total soil erosion. The results illustrate the need to incorporate temporal variability in rainfall magnitude-frequency distributions in landscape evolution models. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Sustainable water resources management require scientifically sound information on precipitation, as it plays a key role in hydrological responses in a catchment. In recent years, mesoscale weather models in conjunction with hydrological models have gained great attention as they can provide high resolution downscaled weather variables. Many cumulus parameterization schemes (CPSs) have been developed and incorporated into three-dimensional Pennsylvania State University/National Center for Atmospheric Research (PSU/NCAR) mesoscale model 5 (MM5). This study has performed a comprehensive evaluation of four CPSs (the Anthes–Kuo, Grell, Betts–Miller and Kain–Fritsch93 schemes) to identify how their inclusion influences the mesoscale model's precipitation estimation capabilities. The study has also compared these four CPSs in terms of variability in rainfall estimation at various horizontal and vertical levels. For this purpose, the MM5 was nested down to resolution of 81km for domain 1 (domain span 21 x 81 km) and 3km for 4 (domain span 16 x 3km) respectively with vertical resolutions at 23, 40 and 53 vertical levels. The study was carried out at the Brue catchment in Southwest England using both the ERA-40 reanalysis data and the land based observation data. The performances of four CPs were evaluated in terms of their ability to simulate the amount of cumulative rainfall in four months in 1995 representing the four seasonal months viz January (winter), March (spring), July (summer) and October (autumn). It is observed that the Anthes–Kuo scheme has produced inferior precipitation values during spring and autumn seasons while simulations during winter and summer were consistently good. The Betts–Miller scheme has produced some reasonable results, particularly at the small scaled domain (3 km grid size) during winter and summer. The KF2 scheme was the best scheme for the larger scale (81 km grid size) domain during winter season at both 23 and 53 vertical levels. This scheme tended to underestimate rainfall for other seasons including the small scale domain (3 km grid size) in the mesoscale. The Grell scheme was the best scheme in simulating rainfall rates, and was found to be superior to other three schemes with consistently better results in all four seasons and different domain scales. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Nonlinear dynamics and spatial variability in hydrological systems make difficult the formulation of scaling theories. Therefore, the development of knowledge related to scale effects, scaling techniques, parameterization and linkages of parameters across scales is highly relevant. The main purpose of this work is to analyse the spatial effect of the static storage capacity parameter H u and the saturated hydraulic conductivity parameter k s from microscale (sub-grid level) to mesoscale (grid level) and its implication to the definition of an optimum cell size. These two parameters describe the upper soil water characteristics in the infiltration process conceptualization of the TETIS hydrological model. At microscale, the spatial heterogeneity of H u and k s was obtained generating random parameter fields through probability distribution functions and a spatial dependence model with pre-established correlation lengths. The effective parameters at mesoscale were calculated by solving the inverse problem for each parameter field. Results indicate that the adopted inverse formulation allows transferring the non-linearity of the system from microscale to the mesoscale via non-stationary effective parameters. Their values at each cell and time step are in the range of zero to the mean value of the parameter at microscale. The stochastic simulations showed that the variance of the estimated effective parameters decreases when the ratio between mesoscale cell size and correlation length at microscale increases. For a ratio greater than 1, we found cell sizes having the characteristics of a representative elementary area (REA); in such case, the microscale variability pattern did not affect the system response at mesoscale. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Markus Jager, Kornelius Iwig, and Tilman Butz A user-friendly fully digital time differential perturbed angular correlation (TDPAC)-spectrometer with six detectors and fast digitizers using field programmable gate arrays (FPGA) is described and performance data are given. The new spectrometer has an online data analysis feature, a compact size, ... [Rev. Sci. Instrum. 82, 065105 (2011)] published Mon Jun 13, 2011.

Beschreibung: Analytical solutions are obtained for optimization formulations that minimize energy used for groundwater pumping. The formulations choose pumping rates at groundwater wells while insuring that total pumpage meets a specified demand. Such formulations might be appropriate for an urban water supply or a large−scale agricultural irrigation system. Solutions are found by applying stationarity conditions. The solutions produce simple and physically meaningful requirements on drawdowns at each well. Under certain conditions, pumping rates are optimal when the sum of the nonpumping lift and two times the drawdown at each pumping well takes a constant value across the domain. The results are examined for steady and transient conditions. The results are based on only a few assumptions on the modeled system: the response of drawdown with head is linear, and all pumping activity occurs during the same time periods. Implications of these results for well field operation are suggested.

Beschreibung: Water pricing schedules often contain significant nonlinearities, such as the increasing block tariff (IBT) structure that is abundantly applied for residential users. The IBT is frequently supported as a good tool for achieving the goals of equity, water conservation, and revenue neutrality but seldom has been grounded on efficiency justifications. In particular, existing literature on water pricing establishes that although efficient schedules will depend on demand and supply characteristics, IBT cannot usually be recommended. In this paper, we consider whether the explicit inclusion of scarcity considerations can strengthen the appeal of IBT. Results show that when both demand and costs react to climate factors, increasing marginal prices may come about as a response to a combination of water scarcity and customer heterogeneity. We derive testable conditions and then illustrate their application through an estimation of Portuguese residential water demand. We show that the recommended tariff schedule hinges crucially on the choice of functional form for demand.

Beschreibung: In situ laser diffractometers characterize the suspended particle size distribution (PSD) by measuring laser-generated light scattered off small particles over a range of small forward angles. In environments with low particulate concentrations or high ambient light conditions the ratio of natural downwelling sunlight to scattered laser light sensed by the photodetectors is high and measurements are influenced. Here, we evaluate the effect of the ambient light field intensity on measurements made with a Laser In Situ Scattering and Transmissometry (LISST) 100X type B instrument. Paired light-dark scattering distributions are recorded over a range of underwater light intensities in high-turbidity and low-turbidity water. Light measurements displayed large erroneous concentrations of particles in the smallest size bin (1.25–1.48 μm) and showed effects over the full range of the PSD. Ambient light was found to exhibit the same constant distribution over the instrument photodetectors in both water samples, although the magnitude of the response, in laser counts per unit ambient light intensity, was PSD dependent. A technique for postprocessing data to remove the influence of light is presented for moored deployment and vertical profile data collected at Lake Tahoe, California-Nevada, United States. While measurements removed of the light effect were successfully reconstructed, the technique may not be applicable to data where the PSD or the LISST orientation relative to the sun direction change rapidly or when light intensities are high enough to quench the instrument photodetectors. Ambient light was found to have negligible effects on PSD measurements in Lake Tahoe was below intensities of ∼30 W m−2.

Beschreibung: Spatial and temporal trends in stream chemistry were investigated in a large (1600 km2) alpine watershed in the southern Rocky Mountains of Colorado to help understand mechanisms of streamflow generation. We observed linear increases of concentrations of chemical constituents in streamflow as accumulated drainage area increased along the main channel of Saguache Creek. We tested two conceptual models of streamflow generation against our stream chemistry observations. One model is essentially two-dimensional and treats streamflow generation at the large watershed scale as the aggregation of runoff responses from individual hillslopes, primarily surface and shallow subsurface flow paths. Alternatively, a fully three-dimensional conceptual model treats streamflow generation as being controlled by a distribution of large-scale groundwater flow paths as well as surface and shallow subsurface flow paths. The structure and magnitude of groundwater contributions in streamflow as a function of increasing scale provided a key distinction between these two conceptual models. End-member mixing analysis and measurements of hydraulic head gradients in streambeds were used to quantify basin-scale groundwater contributions to streamflow with increasing spatial scale in the Saguache Creek watershed. Our data show that groundwater contributions are important in streamflow generation at all scales and, more importantly, that groundwater contributions to streamflow do increase with increasing watershed scale. These results favor the three-dimensional conceptual model in which long groundwater flow paths provide a streamflow generation process at large scales that is not operative at smaller scales. This finding indicates that large watersheds may be more than simply the aggregation of hillslopes and small catchments.

Beschreibung: Microbial biodiversity in groundwater and soil presents a unique opportunity for improving characterization and monitoring at sites with multiple contaminants, yet few computational methods use or incorporate these data because of their high dimensionality and variability. We present a systematic, nonparametric decision-making methodology to help characterize a water quality gradient in leachate-contaminated groundwater using only microbiological data for input. The data-driven methodology is based on clustering a set of molecular genetic-based microbial community profiles. Microbes were sampled from groundwater monitoring wells located within and around an aquifer contaminated with landfill leachate. We modified a self-organizing map (SOM) to weight the input variables by their relative importance and provide statistical guidance for classifying sample similarities. The methodology includes the following steps: (1) preprocessing the microbial data into a smaller number of independent variables using principal component analysis, (2) clustering the resulting principal component (PC) scores using a modified SOM capable of weighting the input PC scores by the percent variance explained by each score, and (3) using a nonparametric statistic to guide selection of appropriate groupings for management purposes. In this landfill leachate application, the weighted SOM assembles the microbial community data from monitoring wells into groupings believed to represent a gradient of site contamination that could aid in characterization and long-term monitoring decisions. Groupings based solely on microbial classifications are consistent with classifications of water quality from hydrochemical information. These microbial community profile data and improved decision-making strategy compliment traditional chemical groundwater analyses for delineating spatial zones of groundwater contamination.

Beschreibung: Legal scholars and jurists have identified several criteria (e.g., hydrology, climate, population, and historical water use) to guide equitable allocation of transboundary rivers among riparian claimants. Are these criteria used in practice, such that a quantitative pattern emerges from actual water-sharing agreements regarding factors affecting allocations? To address this, we study interstate compacts, the principal mechanism for allocating the waters of transboundary rivers within the United States. We develop a georeferenced data set and construct variables representing conditions in state-based watersheds of 14 rivers at the times of compact ratification. A state's water allocation share of a compact serves as the dependent variable, and a set of explanatory variables is derived from legal and political theories. We estimate allocation shares using both ordinary least squares (OLS) and bootstrap regressions, and we apply two alternative specifications of the factors affecting compact allocations, one with and one without political variables. Estimated coefficients on variables for land area, population, prior water use, riparian position, and Congressional committee chair are statistically significant in the OLS regressions. The preferred OLS specification, which includes political variables, provides a good fit (R2 = 0.84). We also find that OLS and bootstrap regressions have a similar ability to predict state allocation shares. We discuss how the results could be used as a reference point in negotiations over new compacts or international river treaties and as a basis to identify existing compacts with statistical outliers.

Beschreibung: Transverse mixing of solutes in steady state transport is of utmost importance for assessing mixing-controlled reactions of compounds that are continuously introduced into the subsurface. Classical spatial moments analysis fails to describe mixing because the tortuous streamlines in heterogeneous formations cause plume meandering, squeezing, and stretching, which affect transverse spatial moments even if there is no mass transfer perpendicular to the direction of flow. For transverse solute mixing, however, the decisive process is the exchange of solute mass between adjacent stream tubes. We therefore reformulate the advection-dispersion equation in streamline coordinates (i.e., in terms of the potential and the stream function values) and analyze how flux-related second central moments of plumes increase with dropping hydraulic potential. We compare the ensemble behavior of these second central moments in random two-dimensional heterogeneous flow fields with the moments in an equivalent homogeneous system, thus defining an equivalent effective transverse dispersion coefficient. Unlike transverse macrodispersion coefficients derived by traditional moment analysis, our mixing-relevant, flux-related coefficient does not increase with travel distance. We present closed-form solutions for the mean enhancement of transverse mixing by heterogeneity in two-dimensional isotropic media for linear laws of local-scale transverse dispersion. The mixing enhancement factor increases with the log conductivity variance but remains fairly low. We also evaluate the variance of our cumulative measure of transverse mixing, showing that heterogeneity causes substantial uncertainty of mixing. The analytical expressions are compared to numerical Monte Carlo simulations for various values of log conductivity variance, indicating good agreement with the analytical results at low variability. In the numerical simulations, we also consider nonlinear models of local-scale transverse dispersion.

Beschreibung: Hydrologic modelers often need to know which method of quantitative precipitation estimation (QPE) is best suited for a particular catchment. Traditionally, QPE methods are verified and benchmarked against independent rain gauge observations. However, the lack of spatial representativeness limits the value of such a procedure. Alternatively, one could drive a hydrological model with different QPE products and choose the one which best reproduces observed runoff. Unfortunately, the calibration of conceptual model parameters might conceal actual differences between the QPEs. To avoid such effects, we abandoned the idea of determining optimum parameter sets for all QPE being compared. Instead, we carry out a large number of runoff simulations, confronting each QPE with a common set of random parameters. By evaluating the goodness-of-fit of all simulations, we obtain information on whether the quality of competing QPE methods is significantly different. This knowledge is inferred exactly at the scale of interest—the catchment scale. We use synthetic data to investigate the ability of this procedure to distinguish a truly superior QPE from an inferior one. We find that the procedure is prone to failure in the case of linear systems. However, we show evidence that in realistic (nonlinear) settings, the method can provide useful results even in the presence of moderate errors in model structure and streamflow observations. In a real-world case study on a small mountainous catchment, we demonstrate the ability of the verification procedure to reveal additional insights as compared to a conventional cross validation approach.

Beschreibung: N. G. Kujala, C. Karanfil, and R. A. Barrea We have developed a compact short focal distance Bent Crystal Laue Analyzer (BCLA) for Cu speciation studies of biological systems with specific applications to cancer biology. The system provides high energy resolution and high background rejection. The system is composed of an aluminum block servi ... [Rev. Sci. Instrum. 82, 063106 (2011)] published Thu Jun 16, 2011.

Beschreibung: Peter I. Chang, Peng Huang, Jungyeoul Maeng, and Sean B. Andersson A novel algorithm is described and illustrated for high speed imaging of biopolymers and other stringlike samples using atomic force microscopy. The method uses the measurements in real-time to steer the tip of the instrument to localize the scanning area over the sample of interest. Depending on th ... [Rev. Sci. Instrum. 82, 063703 (2011)] published Tue Jun 21, 2011.

Beschreibung: Alex Brambilla, Iacopo Osticioli, Austin Nevin, Daniela Comelli, Cosimo D'Andrea et al. In conservation science, one of the main concerns is to extract information from an artistic surface without damaging it. Raman spectroscopy has emerged in recent years as a reliable tool for the non-destructive analysis of a wide range of inorganic and organic materials in works of art and archaeol ... [Rev. Sci. Instrum. 82, 063109 (2011)] published Tue Jun 21, 2011.

Beschreibung: S. Abuazoum, S. M. Wiggins, R. C. Issac, G. H. Welsh, G. Vieux et al. We present an all solid-state, high voltage pulsed power supply for inducing stable plasma formation (density ~10 cm) in gas-filled capillary discharge waveguides. The pulser (pulse duration of 1 [mu]s) is based on transistor switching and wound transmission line transformer technology. For a capill ... [Rev. Sci. Instrum. 82, 063505 (2011)] published Tue Jun 21, 2011.

Beschreibung: Ph. Mauron, M. Bielmann, A. Remhof, and A. Zuttel We present the design and construction of a high-pressure (200 bars) and high-temperature (600 degrees C) x-ray diffraction (XRD) cell for the in situ investigation of the hydrogen sorption of hydrides. In combination with a pressure, composition, and temperature system, simultaneous XRD and volume ... [Rev. Sci. Instrum. 82, 065108 (2011)] published Wed Jun 22, 2011.

Beschreibung: Shilpa Dilipkumar, Alberto Diaspro, and Partha Pratim Mondal Three-dimensional (3D) resolution improvement in multi-photon multiple-excitation-spot-optical microscopy is proposed. Specially designed spatial filter is employed for improving the overall 3D resolution of the imaging system. An improvement up to a factor of 14.5 and sub-femto liter volume excitat ... [Rev. Sci. Instrum. 82, 063705 (2011)] published Wed Jun 22, 2011.

Beschreibung: M. Eisterer, F. Hengstberger, C. S. Voutsinas, N. Horhager, S. Sorta et al. We report on the design and implementation of a rotating sample magnetometer (RSM) operating in the variable temperature insert (VTI) of a cryostat equipped with a high-field magnet. The limited space and the cryogenic temperatures impose the most critical design parameters: the small bore size of t ... [Rev. Sci. Instrum. 82, 063902 (2011)] published Wed Jun 22, 2011.

Beschreibung: I address a range of topics that provide the sociopolitical-technological setting for my professional life. I discuss some influential features of post–World War II world geopolitics, landmark technological developments of that era, and the resulting follow-up technologies that have made it possible to approach various problems in hydrology and water resources. I next address societal needs that have driven developments in hydrology and water resources engineering and follow with a discussion of the modern foundations of our science and what I think are the principal issues in hydrology. I pose three community challenges that when accomplished should advance hydrologic science: data network needs for improving the water budgets at all scales, characterizing subsurface water flow paths, and the information archiving and mining needs from instruments that will generate substantially richer data detail than have been used for most hydrologic work to the present. I then discuss several hydrologic and water resource risk-based decision issues that matter to society to illustrate how such risks have been addressed successfully in the past. I conclude with a long-term community “grand challenge,” the coupled modeling of the ocean-atmosphere-landform hydrologic cycle for the purpose of long–lead time hydrologic prediction.

Beschreibung: F. Beron, G. Soares, and K. R. Pirota We present a setup allowing to characterize the local irreversible behavior of soft magnetic samples. It is achieved by modifying a conventional ac induction magnetometer in order to measure first-order reversal curves (FORCs), a magnetostatic characterization technique. The required modifications w ... [Rev. Sci. Instrum. 82, 063904 (2011)] published Mon Jun 27, 2011.

Beschreibung: Julien Deboucq, Marc Duquennoy, Mohammadi Ouaftouh, Frederic Jenot, Julien Carlier et al. In this paper, Rayleigh waves were generated and studied over a broad frequency range (550 MHz) and from the dispersion phenomenon, two substrate on layer type-samples with thin layer thicknesses of 1 [mu]m and 500 nm, respectively, were characterized. The originality in this paper is the use of sur ... [Rev. Sci. Instrum. 82, 064905 (2011)] published Mon Jun 27, 2011.

Beschreibung: Frederico A. Lima, Christopher J. Milne, Dimali C. V. Amarasinghe, Mercedes Hannelore Rittmann-Frank, Renske M. van der Veen et al. We present the extension of time-resolved optical pump/x-ray absorption spectroscopy (XAS) probe experiments towards data collection at MHz repetition rates. The use of a high-power picosecond laser operating at an integer fraction of the repetition rate of the storage ring allows exploitation of up ... [Rev. Sci. Instrum. 82, 063111 (2011)] published Mon Jun 27, 2011.

Beschreibung: Christopher R. J. Charles An automated freeze-thaw (AFT) instrument for disaggregating meteorites is described. Meteorite samples are immersed in 18.2 MOmega water and hermetically sealed in a clean 30 ml Teflon vial. This vial and its contents are dipped between baths of liquid nitrogen and hot water over a number of cycles ... [Rev. Sci. Instrum. 82, 065102 (2011)] published Wed Jun 8, 2011.

Beschreibung: The scale issue is of central concern in hydrological processes to understand the potential upscaling or downscaling methodologies, and to develop models for scaling the dominant processes at different scales and in different environments. In this study, a typical permafrost watershed in the Qinghai-Tibet Plateau was selected. Its hydrological processes were monitored for four years from 2004 to 2008; measuring the effects of freezing and thawing depth of active soil layers on runoff processes. To identify the nature and cause of variation in the runoff response in different size catchments, catchments ranging from 1.07 km 2 to 112 km 2 were identified in the watershed. The results indicated that the variation of runoff coefficients showed a “V” shape with increasing catchment size during the spring and autumn seasons, when the active soil was subjected to thawing or freezing processes. A two-stage method was proposed to create runoff scaling models to indicate the effects of scale on runoff processes. In summer, the scaling transition model followed an exponential function for mean daily discharge, whereas the scaling model for flood flow exhibited a linear function. In autumn, the runoff process transition across multiple scales followed an exponential function with air temperature as the driving factor. These scaling models demonstrate relatively high simulation efficiency and precision, and provide a practical way for upscaling or downscaling runoff processes in a medium-size permafrost watershed. For permafrost catchments of this scale, the results show that the synergistic effect of scale and vegetation cover is an important driving factor in the runoff response. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Regression based regional flood frequency analysis (RFFA) methods are widely adopted in hydrology. This paper compares two regression based RFFA methods using a Bayesian Generalized Least Squares (GLS) modelling framework; the two are quantile regression technique (QRT) and parameter regression technique (PRT). In this study, the QRT focuses on the development of prediction equations for a flood quantile in the range of 2 to 100 years average recurrence intervals (ARI), while the PRT develops prediction equations for the first three moments of the log Pearson Type 3 (LP3) distribution, which are the mean, standard deviation and skew of the logarithms of the annual maximum flows; these regional parameters are then used to fit the LP3 distribution to estimate the desired flood quantiles at a given site. It has been shown that using a method similar to stepwise regression and by employing a number of statistics such as the model error variance, average variance of prediction, Bayesian information criterion and Akaike information criterion, the best set of explanatory variables in the GLS regression can be identified. In this study, a range of statistics and diagnostic plots have been adopted to evaluate the regression models. The method has been applied to 53 catchments in Tasmania, Australia. It has been found that catchment area and design rainfall intensity are the most important explanatory variables in predicting flood quantiles using the QRT. For the PRT, a total of four explanatory variables were adopted for predicting the mean, standard deviation and skew. The developed regression models satisfy the underlying model assumptions quite well; of importance, no outlier sites are detected in the plots of the regression diagnostics of the adopted regression equations. Based on ‘one-at-a-time cross validation’ and a number of evaluation statistics, it has been found that for Tasmania the QRT provides more accurate flood quantile estimates for the higher ARIs while the PRT provides relatively better estimates for the smaller ARIs. The RFFA techniques presented here can easily be adapted to other Australian states and countries to derive more accurate regional flood predictions. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Synthetic data have long been employed in hydrology for model development and testing. The objective of this study was to generate a synthetic dataset of hydrologic response with higher spatial and temporal resolution than could presently be obtained in the field, spanning a longer period than the typical duration of monitoring campaigns in experimental catchments. The synthetic dataset was generated for a rangeland catchment with the Integrated Hydrology Model (InHM), and is presented for future use by the community. The InHM boundary-value problem is based upon the previously reported hypothetical reality of Tarrawarra-like hydrologic response. Whereas the emphasis in developing the hypothetical reality was on parameterizing InHM to reproduce observations from the Tarrawarra catchment, the emphasis in generating the synthetic dataset is on developing an internally valid hydrologic-response dataset that extends well beyond the period of observations at Tarrawarra. The synthetic dataset spans eleven years of continuous forcing and response data (e.g., integrated response, distributed fluxes, state variable dynamics). The dataset should be useful for a wide range of problems including evaluation of simple rainfall runoff modeling techniques, design of measurement networks, development of data-assimilation algorithms, and studies on information theory. The dataset is available at: ftp://pangea.stanford.edu/pub/loague/. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Julie N. L. Albert, Joey D. Kim, Christopher M. Stafford, and Thomas H. Epps, III Substrate surface energy/chemistry gradients provide a means for high-throughput exploration of the surface interactions that are important in many chemical and biological processes. We describe the implementation of a controlled vapor deposition approach to surface modification that enables the fac ... [Rev. Sci. Instrum. 82, 065103 (2011)] published Thu Jun 9, 2011.

Beschreibung: The likely effects of climate change on the water resources of the eastern Mediterranean and Middle East region are investigated using a high-resolution regional climate model (PRECIS) by comparing precipitation simulations of 2040–2069 and 2070–2099 with 1961–1990. The simulations show about a 10% decline in precipitation across the region by both the middle and the end of the century, with considerable variation between countries and international river basins. Results suggest that per capita water resources will not change particularly significantly in southeastern Europe, where they are relatively plentiful and population growth is minimal. However, in much of the Middle East, climate change coupled with population growth is likely to reduce per capita water resources considerably. This will inevitably result in major social, economic, and environmental change in the region. Countries where the required adaptation is likely to be particularly challenging include Turkey and Syria because of the large agricultural workforces, Iraq because of the magnitude of the change and its downstream location, and Jordan because of its meager per capita water resources coupled with limited options for desalination. If the internal water footprint of the region declines in line with precipitation but the total water footprint of the region increases in line with population, then by midcentury, as much as half the total water needs of the region may need to be provided through desalination and imported in the form of virtual water.

Beschreibung: We review the human actions, proximal stressors and ecological responses for floodplain forests Australia's largest river system—the Murray-Darling Basin. A conceptual model for the floodplain forests was built from extensive published information and some unpublished results for the system, which should provide a basis for understanding, studying and managing the ecology of floodplains that face similar environmental stresses. Since European settlement, lowlands areas of the basin have been extensively cleared for agriculture and remnant forests heavily harvested for timber. The most significant human intervention is modification of river flows, and the reduction in frequency, duration and timing of flooding, which are compounded by climate change (higher temperatures and reduced rainfall) and deteriorating groundwater conditions (depth and salinity). This has created unfavorable conditions for all life-history stages of the dominant floodplain tree (Eucalyptus camaldulensis Dehnh.). Lack of extensive flooding has led to widespread dieback across the Murray River floodplain (currently 79% by area). Management for timber resources has altered the structure of these forests from one dominated by large, widely spreading trees to mixed-aged stands of smaller pole trees. Reductions in numbers of birds and other vertebrates followed the decline in habitat quality (hollow-bearing trees, fallen timber). Restoration of these forests is dependent on substantial increases in the frequency and extent of flooding, improvements in groundwater conditions, re-establishing a diversity of forest structures, removal of grazing and consideration of these interacting stressors.

Beschreibung: B. E. O'Rourke, N. Hayashizaki, A. Kinomura, R. Kuroda, E. J. Minehara et al. Monte Carlo simulations of slow positron production via energetic electron interaction with a solid target have been performed. The aim of the simulations was to determine the expected slow positron beam intensity from a low-energy, high-current electron accelerator. By simulating (a) the fast posit ... [Rev. Sci. Instrum. 82, 063302 (2011)] published Mon Jun 13, 2011.

Beschreibung: Binxin Hu, Buyin Li, Rixin Zhao, and Tiechen Yang Photovoltaic module measurements are predominantly taken by using pulsed solar simulators. However, significant errors can be generated when the existing simulators are applied to current high-efficiency crystalline silicon photovoltaic modules. This paper presents the design and implementation of a ... [Rev. Sci. Instrum. 82, 065104 (2011)] published Mon Jun 13, 2011.

Beschreibung: A. V. Vodopyanov, S. V. Golubev, D. A. Mansfeld, P. G. Sennikov, and Yu. N. Drozdov The results of first experiments on the investigation of plasma of electron cyclotron resonance (ECR) discharge, sustained by CW radiation of technological gyrotron with frequency 24 GHz are considered. The parameters of nitrogen plasma of ECR discharge in magnetic field up to 1 T were investigated ... [Rev. Sci. Instrum. 82, 063503 (2011)] published Mon Jun 13, 2011.

Beschreibung: Root canal preparation may damage NiTi instruments resulting in wear and deformation. The aim of this study was to make a comparative evaluation of the surface topography of the cervical third of four different rotary systems, before and after being used twelve times, in 1.440 resin blocks with simulated root canals with standardized 45° curvatures, and analyzed by atomic force microscopy – AFM. The blocks were divided into four groups and prepared according to the manufacturers recommendations: Group 1 - K3®; Group 2 - Protaper Universal®; Group 3 - Twisted Files® and Group 4 - Biorace®. After each preparation, the instruments were washed and autoclaved. A total of 240 instruments were selected, being 30 new instruments and 30 after having been used for the 12th time, from each group. These instruments were analyzed by AFM and for quantitative evaluation, the mean RMS (Root mean square) values of the cervical third of the specimens from the four groups were used. The result showed that all the rotary files used for the 12th time suffered wear with change in the topography of the cervical region of the active portion of the file (ANOVA p 〈 0.01). Classifying the specimens in increasing order, from the least to the greatest wear suffered, Group 3 (2.8993 nm) presented the least wear, followed by Group 4 (12.2520 nm), Group 1 (36.0043 nm) and lastly, Group 2 (59.8750 nm) with the largest amount of cervical surface wear. Microsc. Res. Tech., 2011. © 2011 Wiley-Liss, Inc.

Beschreibung: We report the use of superresolution fluorescence microscopy for studying the nanoscale distribution of protein colocalization in living mammalian cells. Nanoscale imaging is attained both by a targeted and a stochastic fluorescence on-off switching superresolution method, namely by stimulated emission depletion (STED) and ground state depletion microscopy followed by individual molecular return (GSDIM), respectively. Analysis of protein colocalization is performed by bimolecular fluorescence complementation (BiFC). Specifically, a nonfluorescent fragment of the yellow fluorescent protein Citrine is fused to tubulin while a counterpart nonfluorescent fragment is fused to the microtubulin-associated protein MAP2 such that fluorescence is reconstituted on contact of the fragment-carrying proteins. Images with resolution down to 65 nm prove a powerful new way for studying protein colocalization in living cells at the nanoscale. Microsc. Res. Tech., 2011. © 2011 Wiley-Liss, Inc.

Beschreibung: Trk neurotrophin receptors are transmembrane tyrosine kinase proteins known as TrkA, TrkB, and TrkC. TrkA is the high affinity receptor for nerve growth factor, TrkB is the one for both brain-derived neurotrophic factor and neurotrophin-4, and TrkC is the preferred receptor for neurotrophin-3. In the adult mammalian brain, neurotrophins are important regulators of neuronal function and plasticity. This study is based on Nothobranchius furzeri, a teleost fish that is becoming an ideal candidate as animal model for aging studies because its life expectancy in captivity is of just 3 months. In adult N. furzeri , all three investigated neurotrophin Trk receptors were immunohistochemically detected in each brain region. TrkA positive neuronal perikarya were localized in the dorsal and ventral areas of the telencephalon and in the cortical nucleus; TrkB immunoreactivity was observed in neuronal perikarya of the dorsal and ventral areas of the telencephalon, the diffuse inferior lobe of the hypothalamus, and Purkinje cells; TrkC positive neuronal perikarya were detected in the most aboral region of the telencephalon, in the magnocellular preoptic nucleus and in few neurons dispersed in the hypothalamus. Numerous positive fibers were widely distributed throughout the brain. Radial glial cells lining the mesencephalic and rhombencephalic ventricles showed immunoreactivity to all three Trks. These findings suggest an involvement of neurotrophins in many aspects of biology of adult N. furzeri . Microsc. Res. Tech., 2011. © 2011 Wiley-Liss, Inc.

Beschreibung: TRPV4 is a nonselective cation channel that belongs to the vanilloid (V) subfamily of transient receptor potential (TRP) ion channels. While TRP channels have been found to be involved in sensing temperature, light, pressure, and chemical stimuli, TPRV4 is believed to be primarily a mechanosensor although it can also respond to warm temperatures, acidic pH, and several chemical compounds. In zebrafish, the expression of trpv4 has been studied during embryonic development, whereas its pattern of TPRV4 expression during the adult life has not been thoroughly analyzed. In this study, the occurrence of TRPV4 was addressed in the zebrafish sensory organs at the mRNA (RT-PCR) and protein (Westernblot) levels. Once the occurrence of TRPV4 was demonstrated, the TRPV4 positive cells were identified by using immunohistochemistry. TPRV4 was detected in mantle and sensory cells of neuromasts, in a subpopulation of hair sensory cells in the macula and in the cristae ampullaris of the inner ear, in sensory cells in the taste buds, in crypt neurons and ciliated sensory neurons of the olfactory epithelium, and in cells of the retina. These results demonstrate the presence of TRPV4 in all sensory organs of adult zebrafish and are consistent with the multiple physiological functions suspected for TRPV4 in mammals (mechanosensation, hearing, and temperature sensing), but furthermore suggest potential roles in olfaction and vision in zebrafish. Microsc. Res. Tech., 2011. © 2011 Wiley-Liss, Inc.

Beschreibung: In recent years, bioinorganic nanohybrids composed of biological macromolecules and functional inorganic nanomaterials have revealed many unique properties that show promise for the future. Transmission electron microscopy (TEM) is a popular and relatively simple tool that can offer a direct visualization of the nanomaterials with high resolutions. When TEM is applied to visualize bioinorganic nanohybrids, a treatment of negative staining is necessary due to the presence of biological molecules in the nanohybrids except for those with densely packed inorganic materials. However, the conventional negative-staining procedure for regular biological samples cannot be directly applied to such bioinorganic nanohybrids. To image a specific bioinorganic nanohybrid, negative-staining factors such as negative stain type, working pH, staining time, and drying method, should be identified. Currently, no detailed studies have been done to investigate how to adjust negative-staining factors based on specific bioinorganic nanohybrids. In this study, bacteriophage-gold nanoparticle hybrids were chosen as a model to systematically study the effects of each factor on the negative staining of the nanohybrids. The best staining conditions for gold nanoparticle-phage nanohybrids were obtained and the effects of each factor on the negative staining of general nanohybrids were discussed. This work indicates that with proper staining it is possible to use TEM to visualize directly both biological and inorganic components without introducing any artifact. Microsc. Res. Tech. 2011. © 2011 Wiley-Liss, Inc.

Beschreibung: Yuquan Zhang, Xin Wang, Yijia Wang, Siwei Zhu, Bruce Z. Gao et al. A dynamic optical tweezers system is employed for generation of an optical trap in continuous rotation for manipulating a biological cell in an aqueous solution. When the rotating speed is increased, the trapped cell experiences an augmented viscous drag force, and eventually it escapes from the tra ... [Rev. Sci. Instrum. 82, 064301 (2011)] published Wed Jun 15, 2011.

Beschreibung: E. Magerl, S. Neppl, A. L. Cavalieri, E. M. Bothschafter, M. Stanislawski et al. We describe an apparatus for attosecond photoelectron spectroscopy of solids and surfaces, which combines the generation of isolated attosecond extreme-ultraviolet (XUV) laser pulses by high harmonic generation in gases with time-resolved photoelectron detection and surface science techniques in an ... [Rev. Sci. Instrum. 82, 063104 (2011)] published Wed Jun 15, 2011.

Beschreibung: There is currently a distinct gap between what climate science can provide and information that is practically useful for (and needed by) natural resource managers. Improved understanding, and model representations, of interactions between the various climate drivers (both regional and global scale), combined with increased knowledge about the interactions between climate processes and hydrological processes at the regional scale, is necessary for improved attribution of climate change impacts, forecasting at a range of temporal scales and extreme event risk profiling (e.g., flood, drought, and bushfire). It is clear that the science has a long way to go in closing these research gaps; however, in the meantime water resource managers in the Murray-Darling Basin, and elsewhere, require hydroclimatic projections (i.e., seasonal to multidecadal future scenarios) that are regionally specific and, importantly, take into account the impacts, and associated uncertainties, of both natural climate variability and anthropogenic change. The strengths and weaknesses of various approaches for supplying this information are discussed in this paper.

Beschreibung: Juleon M. Schins and Elise Talgorn An expression is derived for the perturbative response of a lumped resonance circuit to a sudden change in the circuit parameters. This expression is shown to describe also the photo-induced conductivity of a semiconductor mounted in a single-mode microwave cavity. The power dissipated in the cavity ... [Rev. Sci. Instrum. 82, 064703 (2011)] published Thu Jun 16, 2011.

Beschreibung: Evgeny Kleymenov, Jeroen A. van Bokhoven, Christian David, Pieter Glatzel, Markus Janousch et al. A Johann-type spectrometer with five spherically bent crystals and a pixel detector was constructed for a range of hard x-ray photon-in photon-out synchrotron techniques, covering a Bragg-angle range of 6088. The spectrometer provides a sub emission line width energy resolution from sub-eV to a few ... [Rev. Sci. Instrum. 82, 065107 (2011)] published Thu Jun 16, 2011.

Beschreibung: Min-Haw Wang, Min-Feng Kao, and Ling-Sheng Jang This study presents an impedance measurement system for single-cell capture and measurement. The microwell structure which utilizes nDEP force is used to single-cell capture and a minimized impedance spectroscopy which includes a power supply chip, an impedance measurement chip and a USB microcontro ... [Rev. Sci. Instrum. 82, 064302 (2011)] published Fri Jun 17, 2011.

Beschreibung: We use the Budyko framework to calculate catchment-scale evapotranspiration (E) and runoff (Q) as a function of two climatic factors, precipitation (P) and evaporative demand (Eo = 0.75 times the pan evaporation rate), and a third parameter that encodes the catchment properties (n) and modifies how P is partitioned between E and Q. This simple theory accurately predicted the long-term evapotranspiration (E) and runoff (Q) for the Murray-Darling Basin (MDB) in southeast Australia. We extend the theory by developing a simple and novel analytical expression for the effects on E and Q of small perturbations in P, Eo, and n. The theory predicts that a 10% change in P, with all else constant, would result in a 26% change in Q in the MDB. Future climate scenarios (2070–2099) derived using Intergovernmental Panel on Climate Change AR4 climate model output highlight the diversity of projections for P (±30%) with a correspondingly large range in projections for Q (±80%) in the MDB. We conclude with a qualitative description about the impact of changes in catchment properties on water availability and focus on the interaction between vegetation change, increasing atmospheric [CO2], and fire frequency. We conclude that the modern version of the Budyko framework is a useful tool for making simple and transparent estimates of changes in water availability.

Beschreibung: A partially penetrating well of length Lw and radius Rw starts to pump at constant discharge Qw at t = 0 from an unconfined aquifer of thickness D. The aquifer is of random and stationary conductivity characterized by KG (geometric mean), σY2 (log conductivity variance), and I and Iv (the horizontal and vertical integral scales). The flow problem is solved under a few simplifying assumptions commonly adopted in the literature for homogeneous media: Rw/Lw $\ll$ 1, linearization of the free surface condition, and constant drainable porosity n. Additionally, it is assumed that Rw/I 〈 1 and Lw/Iv $\gg$ 1 (to simplify the well boundary conditions) and that a first-order approximation in σY2 (extended to finite σY2 on a conjectural basis) is adopted. The solution is obtained for the mean head field $\langle$H(R, z, t)$\rangle$ and the associated water table equation. The main result of the analysis is that the flow domain can be divided into three zones for $\langle$H$\rangle$: (1) the neighborhood of the well R $\ll$ I, where $\langle$H$\rangle$ = (Qw/LwKA)h0(R, z, tKefuv/nD), with h0 being the zero-order solution pertaining to a homogeneous and isotropic aquifer, KA being the conductivity arithmetic mean, and Kefuv being the effective vertical conductivity in mean uniform flow, (2) an exterior zone R ⪆ I in which $\langle$H$\rangle$ = (Qw/LwKefuh)h0(R$\sqrt{K_{efuv}/K_{efuh}}$, z, tKefuv/nD), with Kefuh being the horizontal effective conductivity, and (3) an intermediate zone in which the solution requires a few numerical quadratures, not carried out here. The application to pumping tests reveals that identification of the aquifer parameters for homogeneous and anisotropic aquifers by commonly used methods can be applied for the drawdown measured in an observation well of length Low $\gg$ Iv (to ensure exchange of space and ensemble head averages) in the second zone in order to identify Kefuh, Kefuv, and n. In contrast, the use of the drawdown in the well (first zone) leads to an overestimation of Kefuh by the factor KA/Kefuh.

Beschreibung: Calcium (Ca) has declined to levels threatening aquatic biota in lakes on the eastern Canadian Shield. Predictive models for future changes in lake Ca are generally based on catchment-scale studies, but these models rarely account for unmeasured sources of Ca supply that are common in the nearshore areas of developed lakes. In this study we utilize up to 29 years of hydrological and water chemistry data for three lakes in central Ontario that differ in degree of human intervention to demonstrate that shoreline development may exert large effects on Ca mass balances. In the relative absence of shoreline development, Red Chalk Lake exhibited what we consider to be the normal response, a reduction in Ca load from the catchment over the last three decades, leading to a reduction in lake export and lake Ca concentration. Calcium load, export, and lake water Ca concentration also fell in Harp Lake, but less than in Red Chalk Lake, because Ca loads were elevated by human activities in Harp Lake's moderately developed shoreline area. By contrast, Dickie Lake experienced an exceptional change in Ca dynamics: both export and lake concentrations rose because of elevated load from the shoreline area linked to the use of dust suppressants on gravel roads. Reductions in both stream Ca concentration and flow volume have led to calcium decline in streams and lakes. Long-term soil acidification processes and climatic variability with its link to hydrology can explain the general pattern of Ca decline in lakes on the south-central Canadian Shield. However, given the widespread lakeshore development and use of dust suppressants on gravel roads, predictions of lake Ca levels need to take into account nearshore activities, especially those that augment rates of Ca supply.

Beschreibung: This work presents a new design of disc infiltrometer, which, associated with a microflowmeter (MF) and a solenoid valve set, makes it possible to automate the infiltration rate ( Q ) measurements at different soil pressure heads (ψ). The MF consists of a 13.8-cm long and 1.5 mm i.d. pipe, with a pressure transducer connecting the two ends of the MF, inserted in a water-flow pipe that connects the Mariotte tube and the water-supply reservoir of the disc infiltrometer. Water flow is calculated from the head losses in the MF. Changes in ψ in the bubble tower, automatically effected when the infiltration rate reaches steady-state, are controlled by a datalogger connected to four solenoid valves. The new design was tested in laboratory and field conditions, and the results showed that the MF allows the soil water infiltration rates to be correctly estimated for different soil characteristics. The solenoid valve set plus datalogger system satisfactorily monitored the changes in ψ and allowed the measurement time to be optimized. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: There are several methods for determining the spatial distribution and magnitude of groundwater inputs to streams. We compared results of conventional methods (dye dilution gauging, acoustic Doppler velocimeter (ADV) differential gauging, and geochemical end-member mixing) to Distributed Temperature Sensing (DTS) using a fiber-optic cable installed along 900 m of Nine Mile Creek in Syracuse, New York, USA during low-flow conditions (discharge = 1.4 m 3 s -1 ). With the exception of differential gauging, all methods identified a focused, contaminated groundwater inflow and produced similar groundwater discharge estimates for that point, with a mean of 66.8 Ls -1 between all methods although the precision of these estimates varied. ADV discharge measurement accuracy was reduced by non-ideal conditions and failed to identify, much less quantify, the modest groundwater input, which was only 5% of total stream flow. These results indicate ambient tracers, such as heat and geochemical mixing, can yield spatially and quantitatively refined estimates of relatively modest groundwater inflow even in large rivers. DTS heat tracing, in particular, provided the finest spatial characterization of groundwater inflow, and may be more universally applicable than geochemical methods, for which a distinct and consistent groundwater end member may be more difficult to identify. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Remote sensing estimates of snow water equivalent (SWE) in mountainous areas are subject to large uncertainties. As a prerequisite for testing passive microwave algorithm estimations of SWE, this study aims to collect snow depth (SD) data and provide an understanding of its complex spatial structure as part of the Canadian International Polar Year observations theme. Snow accumulation, redistribution and ablation are controlled by processes that depend on a variety of topographic factors as well as land surface characteristics, which leads us to modelling SD as a function of proxy variables derived from digital elevation model and Landsat data. Field measurements were performed at 3924 locations compromising 184 sites in 50 transects over two years. These measurements were used to predict SD over the study area using a spatial linear mixed-effects model, a model type capable of handling the hierarchical structure of the field data. The model, built using stepwise variable selection, uses as predictor variables transformed elevation, slope, the logarithm of slope, potential incoming solar radiation and its transform; the normalized difference vegetation index, and a transformed tasseled cap brightness from Landsat imagery. A second, simpler model links SD with density giving SWE. The cross-validated root mean squared error of the SD distribution model was 14 cm around an overall mean of 80 cm over a domain of 250 x 250 km. This instantaneous end-of-season peak-accumulation snow map will enable the validation of satellite remote sensing over a generally inaccessible area. Copyright © 2011 John Wiley & Sons, Ltd.

Beschreibung: Accurate description of the soil water retention curve (SWRC) at low water contents is important for simulating water dynamics and biochemical vadose zone processes in arid environments. Soil water retention data corresponding to matric potentials of less than −10 MPa, where adsorptive forces dominate over capillary forces, have also been used to estimate soil specific surface area (SA). In the present study, the dry end of the SWRC was measured with a chilled-mirror dew point psychrometer for 41 Danish soils covering a wide range of clay (CL) and organic carbon (OC) contents. The 41 soils were classified into four groups on the basis of the Dexter number (n = CL/OC), and the Tuller-Or (TO) general scaling model describing water film thickness at a given matric potential ( 10. A strong correlation between the ratio of the two surface area estimates and the Dexter number was observed and applied as an additional scaling function in the TO model to rescale the soil water retention curve at low water contents. However, the TO model still overestimated water film thickness at potentials approaching ovendry condition (about −800 MPa). The semi–log linear Campbell-Shiozawa-Rossi-Nimmo (CSRN) model showed better fits for all investigated soils from −10 to −800 MPa and yielded high correlations with CL and SA. It is therefore recommended to apply the empirical CSRN model for predicting the dry part of the water retention curve (−10 to −800 MPa) from measured soil texture or surface area. Further research should aim to modify the more physically based TO model to obtain better descriptions of the SWRC in the very dry range (−300 to −800 MPa).

Beschreibung: Ahmed A. Abdel-Hafez, Matthew W. Brodt, Joel R. Carney, and James M. Lightstone The development of a laser-shock technique for dispersing Al metal fuel particles at velocities approaching those expected in a detonating explosive is discussed. The technique is described in detail by quantifying how air drag affects the temporal variation of the velocity of the dispersed particle ... [Rev. Sci. Instrum. 82, 064101 (2011)] published Fri Jun 24, 2011.

Beschreibung: M. Bonetti, S. Nakamae, and M. Roger We have built a simply designed cell for the measurement of the thermal conductivity of liquids under steady state conditions from room temperature to about 60 C. Thermal conductivities measured in the range between 0.2 and 0.7 Wm K show deviations of a few percent from reference thermal-conductivit ... [Rev. Sci. Instrum. 82, 064906 (2011)] published Mon Jun 27, 2011.

Beschreibung: Lih-Horng Shyu, Chung-Ping Chang, and Yung-Cheng Wang Fabry-Perot interferometer is often used for the micro-displacement, because of its common optical path structure being insensitive to the environmental disturbances. Recently, the folded Fabry-Perot interferometer has been investigated for displacement measurements in large ranges. The advantages o ... [Rev. Sci. Instrum. 82, 063103 (2011)] published Mon Jun 6, 2011.

Beschreibung: This paper analyzes the effects of different hydrological mechanisms on the solute response in watershed stream networks. Important processes are due to the hydraulic and chemical retention of reactive solutes in transient storage zones and the cumulative consequences of these processes from a single transport pathway as well as from the network of transport pathways. Temporal moments are derived for a distributed stream network and for a compartment-in-series model. The temporal moments are evaluated and are utilized to derive formal expressions for translating the network parameters into compartmental model parameters. The analysis reveals that in addition to the hydraulic and chemical retention processes, the morphological and topological properties of a watershed have a distinct impact on the central temporal moments in terms of averaging of the solute load weighted distances as well as the transport parameters over the network. Kinetic (rate-limited) transient storage affects second-order and higher central temporal moments and thus has a secondary effect on the parameterization of compartmental models. Additional considerable contributions to all temporal moments are introduced when parameter variability along transport pathways is considered. The paper demonstrates an improved model outcome for phosphorus transport in a small Swedish watershed by accounting for the overall network effects when parameterizing a compartment-in-series model.

Beschreibung: Tairan Fu, Peng Tan, Chuanhe Pang, Huan Zhao, and Yi Shen A fast fiber-optic multi-wavelength pyrometer was developed for the ultraviolet-visible-near infrared spectra from 200 nm to 1700 nm using a CCD detector and an InGaAs detector. The pyrometer system conveniently and quickly provides the sufficient choices of multiple measurement wavelengths using op ... [Rev. Sci. Instrum. 82, 064902 (2011)] published Mon Jun 6, 2011.

Beschreibung: E. Joanni, R. Savu, L. Valadares, M. Cilense, and M. A. Zaghete A tubular furnace specifically designed for growing nanostructured materials is presented in this work. The configuration allows an accurate control of evaporation temperature, substrate temperature, total pressure, oxygen partial pressure, volumetric flow and source-substrate distance, with the pos ... [Rev. Sci. Instrum. 82, 065101 (2011)] published Mon Jun 6, 2011.