Miracle-dz/UniFAR-FTUs huggingface dataset:
Aquifer remediation: A method for estimating mass transfer rate coefficients and an evaluation of pulsed pumping

When pumping contaminated water from an aquifer, contaminant concentrations often decline rapidly, only to rebound when the pump is shut off. One reason for this behavior is that contaminants in the mobile phase are readily removed, but mass transfer from the immobile to the mobile phase is rate limited. Pulsed pumping, in which the pump is periodically turned off, has been suggested as a means to enhance remediation. We conducted a comprehensive comparison of pulsed pumping and continuous pumping for the case of a Gaussian plume, subject to first- order mass transfer during transport, in an aquifer with no regional gradient and constant mass transfer rate coefficients. We developed a Laplace domain Green's function solution for concentrations during pumping periods and coupled it with an analytic solution for concentrations during resting periods. First, we used this model to provide a simple type curve that can be used to estimate the mobile-immobile phase mass transfer coefficients from field data. Second, the mass and concentration removal histories were determined during pulsed pumping and during continuous pumping. The continuous pumping rate removed the same volume of water over the duration of remediation. We investigated the effects of physical parameters such as the mass transfer rate coefficients, and engineering design parameters such as the length of resting periods. Under the conditions considered, our evaluation shows that (1) for equal volumes of water removed, pulsed pumping does not remove more contaminant mass than pumping continuously at an average rate; (2) if the duration of the resting period is too large, then pulsed pumping removes much less mass than continuous pumping at the average rate, and (3) if the pulsed and continuous pumping rates are the same, pulsed pumping will take longer than continuous pumping to clean up the aquifer, but will require significantly less time during which the pump operates.
Single- and Multigrain Luminescence Dating of Sediments Related to the Greenville Fault, Eastern San Francisco Bay Area, California

Near urban areas and extending ∼60 km along the eastern margin of the Livermore Valley, the Greenville fault is the easternmost right-lateral strike-slip fault of the San Andreas system in the greater San Francisco Bay area. Notwithstanding the 1980 Livermore earthquake sequence (mainshock M L 5.9) on the Greenville fault, there is no record of recency or of Holocene rates of activity on the Greenville fault, yet this fault exhibits clear geomorphic evidence of late Quaternary faulting. In trenches parallel and normal to the fault through alluvial fan deposits at the Laughlin Road site only pedogenic carbonate was available for ! [Graphic][1] dating. Therefore, we applied several photon-stimulated luminescence (PSL) sediment-dating procedures to the silt and sand fractions of six samples. The polymineral-fine-silt multi-aliquot age estimates are generally inaccurate, but the single-grain quartz (SGQ) and multigrain quartz single-aliquot regenerative-dose (SAR) ages from sand grains are in stratigraphic sequence. In trench 3A these SAR ages range from 125±11 yrs (before 2007) within the topmost unit L to 13.45±0.79 ka in the base of the lowermost channel-fill unit G. The SAR PSL results demonstrate the importance of the use of SGQ dating for such sediments and provide the first numerical ages used to constrain the slip rate on the Greenville fault. Trench exposures reveal that unit G is an alluvial sequence infilling a paleochannel offset in a right-lateral sense along the northern Greenville fault. Age estimates from upper and middle unit G bracket deposition of subunit Gb are between 11.12±0.55 ka and 10.64±0.85 ka and those from middle and lower unit G bracket deposition of subunit Go are between 11.12±0.55 ka and 13.45±0.79 ka. These SAR PSL age estimates and measurements of the lateral offset constrain a preliminary slip-rate estimate to about 2 mm/yr or higher for the northern Greenville fault zone. [1]: /embed/inline-graphic-1.gif
Potential Predictability of North American Surface Temperature. Part I: Information-Based versus Signal-To-Noise-Based Metrics

AbstractIn this study, the potential predictability of the North American (NA) surface air temperature was explored using information-based predictability framework and Ensemble-Based Predictions of Climate Changes and their Impacts (ENSEMBLES) multiple model ensembles. Emphasis was put on the comparison of predictability measured by information-based metrics and by the conventional signal-to-noise ratio (SNR)-based metrics. Furthermore, the potential predictability was optimally decomposed into different modes by maximizing the predictable information (equivalent to the maximum of SNR), from which the most predictable structure was extracted and analyzed.It was found that the conventional SNR-based metrics underestimate the potential predictability, in particular in these areas where the predictable signals are relatively weak. The most predictable components of the NA surface air temperature can be characterized by the interannual variability mode and the long-term trend mode. The former is inherent to .
Basic characteristics of canopy turbulence in a homogeneous rice paddy

[1] To assess the interactions of key ecosystems with the overlying atmosphere, it is fundamental to understand the turbulence structure within and above their canopies. Rice is a staple crop particularly in Asia, and, yet, information on canopy turbulence of this vital food resource is limited by the scarcity of field measurement. The purpose of this study was to examine whether rice canopy shows an organized turbulence structure and, if so, whether such coherent structure scales to the patterns found in other canopies. Using the field data obtained during the 1996 International Rice Experiment (IREX96), we computed turbulence statistics such as mean, standard deviation, covariance, skewness, kurtosis, and turbulence length scales. When appropriately scaled with canopy height and friction velocity, these turbulence statistics showed coherent structures, which agreed well within the ranges of those reported for other canopies. Both quadrant and spectrum analyses confirmed that the intermittent and energetic eddies with length scale of the order of canopy height dominated the transfer processes within and above rice canopy. Such results were further substantiated by the countergradient fluxes observed during the IREX96. Furthermore, within-canopy turbulence became more intermittent under stable conditions.
Total ozone and solar erythemal irradiance in southwestern Spain: Day‐to‐day variability and extreme episodes

This paper focuses on the influence of short‐term changes in total ozone column (TOC) on the variability of ultraviolet erythemal irradiance (UVER) at Badajoz (southwestern Spain). The study is performed on clear sky cases when the contribution of cloudiness and aerosols can be neglected. The period of study extends from 2001 to 2005. The results show that a reduction of 5% in TOC between two consecutive days may cause an increase of about 10% in UVER. The UVER variability associated to day‐to‐day changes in TOC presents a clear seasonal cycle with minimum values in summer and maximum in winter. Considering the monthly mean TOC value plus/minus two standard deviation as thresholds for identifying extreme events, the number of episodes with extreme low and high ozone amount was 54 and 9, respectively. The low ozone events occurred mainly in winter, causing a maximum increase of 30% in UVER.
An Evaluation of the Bouwer and Rice Method of Slug Test Analysis

The method of Bouwer and Rice (1976) for analyzing slug test data is widely used to estimate hydraulic conductivity (K). Based on steady state flow assumptions, this method is specifically intended to be applicable to unconfined aquifers. Therefore it is of practical value to investigate the limits of accuracy of the K estimates obtained with this method. Accordingly, using a numerical model for transient flow, we evaluate the method from two perspectives. First, we apply the method to synthetic slug test data and study the error in estimated values of K. Second, we analyze the logical basis of the method. Parametric studies helped assess the role of the effective radius parameter, specific storage, screen length, and well radius on the estimated values of K. The difference between unconfined and confined systems was studied via conditions on the upper boundary of the flow domain. For the cases studied, the Bouwer and Rice analysis was found to give good estimates of K, with errors ranging from 10% to 100%. We found that the estimates of K were consistently superior to those obtained with Hvorslev's (1951) basic time lag method. In general, the Bouwer and Rice method tends to underestimate K, the greatest errors occurring in the presence of a damaged zone around the well or when the top of the screen is close to the water table. When the top of the screen is far removed from the upper boundary of the system, no difference is manifest between confined and unconfined conditions. It is reasonable to infer from the simulated results that when the screen is close to the upper boundary, the results of the Bouwer and Rice method agree more closely with a “confined” idealization than an “unconfined” idealization. In effect, this method treats the aquifer system as an equivalent radial flow permeameter with an effective radius, Re, which is a function of the flow geometry. Our transient simulations suggest that Re varies with time and specific storage. Thus the effective radius may be reasonably viewed as a time-averaged mean value. The fact that the method provides reasonable estimates of hydraulic conductivity suggests that the empirical, electric analog experiments of Bouwer and Rice have yielded shape factors that are better than the shape factors implicit in the Hvorslev method.
Surface movements of emplaced lava flows measured by synthetic aperture radar interferometry

Lava flows continue to move after they have been emplaced by flow mechanisms. This movement is largely vertical and can be detected using differential synthetic aperture radar (SAR) interferometry. There are three main components to this motion: (1) movement of surface scatterers, resulting in radar phase decorrelation, (2) measurable subsidence of the flow surface due to thermal contraction and clast repacking, and (3) time-dependent depression of the flow substrate. These effects act in proportion to the thickness of the lava flow and decay with time, although there is a time lag before the third component becomes significant. We explore these effects using SAR data from the ERS satellites over the Etna volcano, Sicily. Phase decorrelation on young, thick a’a lava flows persists for a few years and probably results from surface block rotations during flow contraction. Maximum measured subsidence rates of the 1991–1993 lava flow over a period of 70 days are about 0.7 mm day−1, but are potentially greater in areas of data decorrelation. These rates fall to <2.7×10−2 mm day−1 after about 20 years in flows about 50 m thick, sooner for thinner flows. Comparison with measured subsidence rates on Kilauean lava lakes suggests that thermal contraction only accounts for about one third of the observed subsidence. The remaining motion is thought to come from surface clast repacking during cooling and from creep mechanisms in the flow substrate. Measurements of postemplacement surface movement provide new constraints on the thermomechanical properties of lava flows and have cautionary implications for the interpretation of interferometric SAR data of volcanoes. © 2001 American Geophysical Union.
Prediction of Ground Surface Temperature and Soil Moisture Content by the Force‐Restore Method

The parsimony and computational efficiency offered by the force-restore approximation of the diffusion equation have motivated its widespread application in modeling ground surface temperature. Different assumptions regarding the definition of ground surface temperature have resulted in different versions of the force-restore method. Here, four existing versions of the force-restore method for ground surface temperature are compared and contrasted. An improved version of the force-restore method is developed by minimizing the error produced by the force-restore approximation of the heat diffusion equation. The proposed model performs well for the physically realistic ranges of scaled soil thickness and reproduces amplitude and phase that are quite close to the exact solution of the diffusion equation under a single periodic forcing. It is shown that neglect of higher harmonics can produce appreciable errors in the force-restore method if the upper soil thickness is less than the damping depth of the diurnal forcing. The success of the force-restore approximation in modeling ground surface temperature has prompted its application in the prediction of soil moisture content. However, extension of the force-restore method for the prediction of soil moisture content is not straightforward. There are two major difficulties in modeling soil moisture content by the force-restore method. One is the situation-dependent relative importance of the suction term and gravity term in the Richards equation and the other is the choice of state variable, moisture content versus suction head, in the solution of the force-restore method for soil moisture prediction. Both of these could produce appreciable errors in the force-restore treatment of soil moisture evolution.
Late Quaternary turbidity current pathways to the Madeira Abyssal Plain and some constraints on turbidity current mechanisms

Turbidites deposited in the Madeira Abyssal Plain during the last 200 000 yr originated mainly from the flanks of the Canary Islands and from the Northwest African continental margin north of the Canaries. Derivation of these turbidites from sources to the east of the abyssal plain apparently contradicts flow direction indicators derived from the sediments on the plain, which indicate derivation from the north-east. However, two systems of shallow channels, mapped using side-scan sonar and 3.5-kHz data, link the easterly sediment sources to the north-eastern edge of the abyssal plain, reconciling the apparently contradictory flow direction data. A northern system originates in the area between Madeira and the Canary Islands and follows a wester14 and then north-westerly path, in part cutting obliquely across regional bathymetric trends. It carries sediment from the African continental margin north of the Canary Islands, and from the eastern Canaries, to the north-eastern abyssal plain. The southern channel system carries material from the western Canary Islands more directly westward to the central part of the plain. The pathways of individual turbidites can be reconstructed in some detail, by combining channel mapping with published information on turbidite provenance and flow directions on the Madeira Abyssal Plain. Interaction between turbidity currents and channel morphology controls turbidite depositional patterns. Small turbidites are completely contained within channels 20 m deep and 2 km wide. It is proposed that these are relatively high-density flows which have evolved in crossing the almost flat floor of a basin south-east of Madeira before entering the channel system. Larger turbidites show evidence of flow stripping where they interact with channels, with the result that their coarse and fine fractions follow different paths to and across the abyssal plain.
Salt Accumulation and Flushing in Unsaturated Fractures in an Arid Environment

Salt precipitation and dissolution in fractured chalk was investigated through flow experiments in both the laboratory and the field (in the Negev Desert, Israel). In the laboratory, a flow‐cell experimental setup was used to simulate intermittent Infiltration and drying periods along coated and uncoated fracture surfaces. Three Infiltration events, lasting 24, 8, and 8 hours, were carried out with long drying periods of 82 and 44 days between them. In the field, two flow experiments were conducted through a single fracture. Water was percolated from land surface through a discrete fracture into a compartmental sampler. The duration of the two field experiments was 5 and 119 hours, respectively, with a drying period of seven months between them. The percolating outflows in both the laboratory and field experiments were collected and analyzed for electrical conductivity.
Caffeine inhibits gene conversion by displacing Rad51 from ssDNA

Efficient repair of chromosomal double-strand breaks (DSBs) by homologous recombination relies on the formation of a Rad51 recombinase filament that forms on single-stranded DNA (ssDNA) created at DSB ends. This filament facilitates the search for a homologous donor sequence and promotes strand invasion. Recently caffeine treatment has been shown to prevent gene targeting in mammalian cells by increasing non-productive Rad51 interactions between the DSB and random regions of the genome. Here we show that caffeine treatment prevents gene conversion in yeast, independently of its inhibition of the Mec1ATR/Tel1ATM-dependent DNA damage response or caffeine's inhibition of 5′ to 3′ resection of DSB ends. Caffeine treatment results in a dosage-dependent eviction of Rad51 from ssDNA. Gene conversion is impaired even at low concentrations of caffeine, where there is no discernible dismantling of the Rad51 filament. Loss of the Rad51 filament integrity is independent of Srs2's Rad51 filament dismantling activity or Rad51's ATPase activity and does not depend on non-specific Rad51 binding to undamaged double-stranded DNA. Caffeine treatment had similar effects on irradiated HeLa cells, promoting loss of previously assembled Rad51 foci. We conclude that caffeine treatment can disrupt gene conversion by disrupting Rad51 filaments.
The two‐day wave in a middle atmosphere GCM

A strong signal of the two-day wave is diagnosed in a middle atmosphere GCM, with characteristics very similar to those of the observed two-day wave. It results from an instability, but its global structure shows similarities to a Rossby-gravity planetary normal mode. It has a remarkable potential vorticity structure in wave 3 and sometimes wave 4 and higher wavenumbers. It is shown that gravity wave drag is important in maintaining the unstable zonal mean state.
Three‐dimensional solar radiation effects on the actinic flux field in a biomass‐burning plume

[1] Three-dimensional (3-D) solar radiative transfer models describe radiative transfer under inhomogeneous atmospheric conditions more accurately than the commonly used one-dimensional (1-D) radiative transfer models that assume horizontal homogeneity of the atmosphere. Here results of 3-D radiative transfer simulations for a biomass-burning plume are presented and compared with local one-dimensional (l-1-D) simulations, i.e., 1-D simulations in every column of the model domain. The spatial distribution of the aerosol particles was derived from a 3-D atmospheric transport simulation. We studied the impact of 3-D radiative effects on the actinic flux within the plume center. The differences in the actinic flux between results from the 3-D and the l-1-D simulations are considerable, ranging from � 40% to more than +200%, depending on the wavelength, solar zenith angle, and the absorbing properties of the aerosol. The reason for this discrepancy is the neglect of horizontal photon transport in the 1-D simulation. These large 3-D effects on the actinic flux have the potential to influence significantly the in-plume photochemistry. INDEX TERMS: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801); 0345 Atmospheric Composition and Structure: Pollution— urban and regional (0305); 3359 Meteorology and Atmospheric Dynamics: Radiative processes; KEYWORDS: biomass burning plume, actinic flux, 3-D solar radiative transfer simulations, aerosol absorption
Reservoir stress path characterization and its implications for fluid-flow production simulations

ABSTRACT The reduction of fluid pressure during reservoir production promotes changes in the effective and total stress distribution within the reservoir and the surrounding strata. This stress evolution is responsible for many problems encountered during production (e.g. fault reactivation, casing deformation). This work presents the results of an extensive series of 3D numerical hydro-mechanical coupled analyses that study the influence of reservoir geometry and material properties on the reservoir stress path. The stress path is defined in terms of parameters that quantify the amount of stress arching and stress anisotropy that occur during reservoir production. The coupled simulations are performed by explicitly coupling independent commercial geomechanical and flow simulators. It is shown that stress arching is important in reservoirs with low aspect ratios that are less stiff than the bounding material. In such cases, the stresses will not significantly evolve in the reservoir, and stress evolution occurs in the over- and sideburden. Stiff reservoirs, relative to the bounding rock, exhibit negligible stress arching regardless of the geometry. Stress anisotropy reduces with reduction of the Young's modulus of the bounding material, especially for low aspect ratio reservoirs, but as the reservoir extends in either or both of the horizontal directions, the reservoir deforms uniaxially and the horizontal stress evolution is governed by the Poisson's ratio of the reservoir. Furthermore, the effect of the stress path parameters is introduced in the calculation of pore volume multiplier tables to improve non-coupled simulations, which otherwise overestimate the average reservoir pore pressure drawdown when stress arching is taking place.
The covariant graviton propagator in de Sitter spacetime

We consider the covariant graviton propagator in de Sitter spacetime in a gauge with two parameters, α and β, in the Euclidean approach. We give an explicit form of the propagator with a particular choice of β but with an arbitrary value of α. We confirm that two-point functions of local gauge-invariant quantities do not increase as the separation of the two points becomes large.