Analogous Experiments Research Articles

The role of inherited crustal and lithospheric architecture during the evolution of the Red Sea: Insights from three dimensional analogue experiments

The Red Sea represents an incipient ocean basin that is in transition from continental rifting to ocean initiation. In this paper we assess how pre-existing mantle and crustal heterogeneities within the African and Arabian lithospheres influenced rift development and propagation using three-dimensional (3D) brittle-ductile analogue laboratory experiments with a rotational boundary condition. Here we investigate the effect of three different configurations: (i) pre-existing rheological heterogeneities in the crust, (ii) in the lithospheric mantle, and (iii) in both. The experimental outcomes show that a linear weak zone in the lithospheric mantle layer exerts a first-order control on the overall mechanical behaviour of extending lithosphere, rift architecture and style of rifting. Crustal heterogeneities control second-order features, such as the trends of the main boundary escarpments along the rift axis. Our experiments reproduce the geological history of the Red Sea and provide key insights on its deformation history in space and time. We provide, for the first time, 3D dynamic constraints on how pre-existing weak zones in the lithosphere have controlled the temporal evolution of the Red Sea and determined its distinctive present-day morphology. The results find that certain morphological elements of the Red Sea can only be explained by the combined effects of crustal and mantle lithosphere heterogeneities. When applied to other natural examples, our findings provide significant new insights on the role of crustal and lithospheric heterogeneities during continental rifting.

Discriminating Abiotic and Biotic Fingerprints of Amino Acids and Fatty Acids in Ice Grains Relevant to Ocean Worlds.

Identifying and distinguishing between abiotic and biotic signatures of organic molecules such as amino acids and fatty acids is key to the search for life on extraterrestrial ocean worlds. Impact ionization mass spectrometers can potentially achieve this by sampling water ice grains formed from ocean water and ejected by moons such as Enceladus and Europa, thereby exploring the habitability of their subsurface oceans in spacecraft flybys. Here, we extend previous high-sensitivity laser-based analog experiments of biomolecules in pure water to investigate the mass spectra of amino acids and fatty acids at simulated abiotic and biotic relative abundances. To account for the complex background matrix expected to emerge from a salty Enceladean ocean that has been in extensive chemical exchange with a carbonaceous rocky core, other organic and inorganic constituents are added to the biosignature mixtures. We find that both amino acids and fatty acids produce sodiated molecular peaks in salty solutions. Under the soft ionization conditions expected for low-velocity (2-6 km/s) encounters of an orbiting spacecraft with ice grains, the unfragmented molecular spectral signatures of amino acids and fatty acids accurately reflect the original relative abundances of the parent molecules within the source solution, enabling characteristic abiotic and biotic relative abundance patterns to be identified. No critical interferences with other abiotic organic compounds were observed. Detection limits of the investigated biosignatures under Enceladus-like conditions are salinity dependent (decreasing sensitivity with increasing salinity), at the μM or nM level. The survivability and ionization efficiency of large organic molecules during impact ionization appear to be significantly improved when they are protected by a frozen water matrix. We infer from our experimental results that encounter velocities of 4-6 km/s are most appropriate for impact ionization mass spectrometers to detect and discriminate between abiotic and biotic signatures.

Analog and Numerical Experiments of Double Subduction Systems With Opposite Polarity in Adjacent Segments

AbstractIn this work we study the dynamics of double subduction systems with opposite polarity in adjacent segments. A combined approach of numerical and analog experiments allows us to compare results and exploit the strengths of both methodologies. High‐resolution numerical experiments complement laboratory results by providing quantities difficult to measure in the laboratory such as stress state, flow patterns, and energy dissipation. Results show strong asymmetries in the mantle flow that produce in turn asymmetries in the trench and in the downgoing slab deformation. The mantle flow pattern varies with time; the toroidal cells between the plates evolve until merging into one unique cell when the trenches align. In that moment the maximum upward flow is observed close to the trenches. The interaction between the mantle flow produced by each subducting plate makes the rollback processes slower than in a single subduction case. This is consistent with the observed energy dissipation rate that is smaller in the double subduction system than in two single subductions. Moreover, we provide a detailed analysis on the setup and boundary conditions required to numerically reproduce the analog experiments. Boundary conditions at the bottom of the domain are crucial to reproduce their analog counterparts. Numerical results are compared to natural examples of multi‐slab subduction systems in terms of upper mantle seismic anisotropy, relative trench retreat velocities, and composition of subduction‐related magmatism.

Shear Wave Measurements of a Gelatin’s Young’s Modulus

We present a technique to measure the Young’s modulus of a gelatin, using shear waves. Gelatin is a commonly used material for analogue experiments in geophysics, investigating fluid-filled fractures like magmatic dikes, as well as fault slip. Using polarized filters, the deviatoric stresses in a block of gelatin become visible, as do the stress perturbation induced by waves propagating through the medium. We demonstrate how the wave velocity can be measured and related to the Young’s modulus, as well as processing techniques that improve the measurement precision. This methodology is simple to implement into a laboratory setting, can make precise, time-efficient estimates of the material strength and additionally is non-destructive and can be performed in situ.

Experimental and numerical investigation of CO2–brine–rock interactions in the early Palaeozoic mudstones from the Polish part of the Baltic Basin at simulatedin situ conditions

AbstractThis study discusses experiment‐induced alterations of shale rocks collected across the ordovician and silurian boundary at a potential site for carbon dioxide sequestration located in the Polish part of the Baltic Basin. Mudstone samples submerged in brine in custom‐built reactors were subjected to CO2 pressures of 30–35 MPa at a temperature of 80°C for 40 days. After the experiments were completed, the mineralogical composition of the studied rocks, their porosity characteristics, and chemistry of brines were analyzed and compared to the original compositions in order to detect experiment‐induced changes. Comparison of mineral composition before and after the experiments demonstrate a set of subtle but systematic mineral changes. The most conspicuous was a presence of Fe in the form of Fe‐oxyhydroxides that was related to the corrosion of the Fe‐bearing steel pipes supplying the experimental setup with CO2. This effect is important from the perspective of industrial carbon dioxide sequestration. However, the second source of Fe ions in experimental brines was related to the decomposition of chlorites, pyrite, and chloritized biotites. The suggested breakdown of pyrite is in line with the modification of the chemical composition of the experimental brines and observed transfer of S ions to the solution. The appearance of Mg and K ions in the experimental brines was related to the decomposition of chlorites and biotites. In turn, observed transfer of Sr cations to the solution could be attributed to the dissolution of biotites and K‐feldspars. The effects of analogue experiments were confronted with the results of geochemical modeling performed using the PHREEQC program. The numerical modeling not only allowed to reproduce all the main mineral and chemical changes postulated on the basis of our analogue experiment, but also enabled to put constraints on the time scale of occurring geochemical processes. © 2020 Society of Chemical Industry and John Wiley & Sons, Ltd.

The analogue experiment of small space debris impact inducing solar array discharge

High density and conductivity plasma will be induced when space debris impacts with spacecraft. The plasma can lead to a temporary discharge tunnel and triggering discharge. This has been reported as the mechanism of space debris impact inducing discharge and might be a big threat to spacecraft. The solar array is of vital importance to spacecraft and is regarded as vulnerable to space debris impact inducing discharge. Research of space debris larger than 1 mm impact solar array discharge has already carried out. Space debris smaller than 1 mm are predominant and will impact with spacecraft more frequently compared to space debris larger than 1 mm. If the impact of such debris with solar array can induce discharge, the threat will be more serious. However, the study of space debris smaller than 1 mm impacting solar array inducing discharge has not been reported. In this paper, the analogue experiment of smaller than 1 mm space debris impact solar array inducing discharge is carried out. Our results show that the space debris with 200 μm in diameter can trigger solar array discharge. If the voltage is high and the discharge current is large enough, secondary discharge can be triggered too. The discharge can make noticeable mechanical damage on the surface of solar cells.

Electrolytic Reduction of Bicarbonate into CO

Electrolyzers designed to convert CO2 into carbon products typically rely on a gaseous CO2 feedstock or CO2-saturated electrolyte. We show herein that aqueous HCO3- solutions can also be electrochemically converted into CO gas at meaningful rates in a flow cell containing a bipolar membrane (BPM) and a silver catalyst on a carbon support. Electrolysis upon a N2-saturated 3.0-M KHCO3 solution yields CO with a faradaic efficiency that is comparable to analogous experiment where the bicarbonate solution is saturated with gaseous CO2. This electrolytic process is made possible by reaction of protons, delivered by the BPM, with bicarbonate to form electrocatalytically active CO2. This reaction pathway offers the potential to use electrolysis to bypass the thermally-intensive step of extracting CO2 from HCO3- solutions generated in carbon capture schemes.

Role of erosion in creating thrust recesses in a critical-taper wedge: An example from Eastern Tibet

Mechanical models and analog experiments show that erosion plays an important role in controlling along-strike variations in thrust-belt deformation. Despite this fundamental insight, natural examples of focused erosion causing local variations of thrust-belt geometry, such as the formation of salients and recesses, remain underappreciated. In this study, we address this issue by integrating theoretical model predictions with structural, morphological, and erosion-pattern analyses along the thrust system defining the eastern margin of the Tibetan Plateau. Our work shows a nearly constant surface slope across and an overall cylindrical fault-related fold geometry along the thrust belt. These phenomena can be explained by the development of a critically-tapered thrust wedge along the plateau margin. A prominent recess exists at the intersection between the transverse Minjiang River and the range-bounding thrust. There, the surface trace displays a much higher curvature than the rest of the thrust belt and the local fold geometry is conical rather than cylindrical. We infer a warped passive-roof duplex under the recess. We build a classification diagram for recesses developing in critical-taper wedges, in which six independent variables lead to three morphotectonic scenarios regarding the effects of mass influx, mass efflux, and intrinsic properties of a thrust wedge. Formation of the Dujiangyan recess and its spatial correlation to the Minjiang River can be best attributed to localized fluvial erosion during forward propagation of the thrust wedge in eastern Tibet. This study sets a type example for map-view curves in thrust belts undergoing deformation-erosion interactions.

Estimating the depth and evolution of intrusions at resurgent calderas: Los Humeros (Mexico)

Abstract. Resurgent calderas are excellent targets for geothermal exploration, as they are associated with the shallow emplacement of magma, resulting in widespread and long-lasting hydrothermal activity. Resurgence is classically attributed to the uplift of a block or dome resulting from the inflation of the collapse-forming magma chamber due to the intrusion of new magma. The Los Humeros volcanic complex (LHVC; Mexico) consists of two nested calderas: the outer and older Los Humeros formed at 164 ka and the inner Los Potreros formed at 69 ka. The latter is resurgent and currently the site of an active and exploited geothermal field (63 MWe installed). Here we aim to better define the characteristics of the resurgence in Los Potreros by integrating fieldwork with analogue models and evaluating the spatio-temporal evolution of the deformation as well as the depth and extent of the intrusions responsible for the resurgence, which may also represent the local heat source(s). Structural field analysis and geological mapping show that the floor of the Los Potreros caldera is characterized by several lava domes and cryptodomes (with normal faulting at the top) that suggest multiple deformation sources localized in narrow areas. Analogue experiments are used to define the possible source of intrusion responsible for the observed surface deformation. We apply a tested relationship between the surface deformation structures and depth of elliptical sources to our experiments with sub-circular sources. We found that this relationship is independent of the source and surface dome eccentricity, and we suggest that the magmatic sources inducing the deformation in Los Potreros are located at very shallow depths (hundreds of metres), which is in agreement with the well data and field observations. We propose that the recent deformation at LHVC is not a classical resurgence associated with the bulk inflation of a deep magma reservoir; rather, it is related to the ascent of multiple magma bodies at shallow crustal conditions (<1 km depth). A similar multiple source model of the subsurface structure has also been proposed for other calderas with an active geothermal system (Usu volcano, Japan), suggesting that the model proposed may have wider applicability.

Mid-crustal ramping of the Main Himalayan Thrust in Nepal to Bhutan Himalaya: New insights from analogue and numerical experiments

The mid-crustal ramp on the Main Himalayan Thrust (MHT) in the Lesser Himalaya Sequence (LHS) is the most critical geometrical asperity to trigger major seismic events in the Himalaya, including the 2015 Mw 7.8 Gorkha, Nepal earthquake. However, it is still not well understood what caused the MHT to ramp up at laterally varying locations in central to eastern Himalaya during the southward propagation of the Himalayan tectonic wedge. Based on laboratory and numerical model experiments, approximated to the central (Nepal) and eastern (Bhutan) Himalayan geological settings, we show that the coal-bearing Gondwana horizon in the stratigraphic sequence has played a crucial role in producing the mid-crustal ramp on the MHT. During the southward propagation of the Himalayan wedge, the mechanically weak Gondwana sequence resulted in strain localization at its northern edge, and it eventually caused the MHT to ramp from a depth of >20 km to ~6–7 km. Combining our experimental and field observations with the geophysical sections, we interpret that a strike-wise non-uniform occurrence of the Gondwana horizon is responsible for the MHT to ramp at different locations, separated by N-S trending natural barriers, like tear faults. The weak-zone model also explains the rock uplift versus erosion pattern recorded in central Nepal. The ramp-induced surface uplift rates, calculated from our model, are in good agreement with those reported from central Nepal (U* ~ 0.28, normalized to the convergent rate).

Reversible associations between human plasma fibronectin and fibrinogen γγ’ heterodimer observed by high pressure size exclusion chromatography and dynamic light scattering

We previously reported on a novel fibrin matrix having increased viscoelastic strength derived from human plasma fibronectin (pFN) and γγ′-fibrinogen (γγ′-FI). Here we use high pressure size exclusion chromatography (HPSEC) and dynamic light scattering (DLS) to observe interactions between the linearly extended conformation of γγ′-FI and random coiled pFN. Distinct γγ′-FI:pFN subpopulations were fractionated where each maintained unique retention times when individually reprocessed by HPSEC. The hydrodynamic sizes by HPSEC and DLS for these reprocessed subfractions were intermediate to that of pure γγ′-FI and pFN. SDS-PAGE analysis showed that the majority of these subfractions contained intact γγ′-FI and pFN. Importantly, after disruption and isolation using Gelatin Sepharose affinity chromatography, new complexes rapidly formed between pFN and γγ′-FI when mixed back together. This also occurred in analogous mixing experiments between Des-Aα γγ′-FI and pFN where both Aα-chains are reduced by about 15 kDa due to proteolysis. The reversible complexation observed using HPSEC and DLS was not observed in prior studies using SPR indicating that unrestricted freedom of motion is needed to efficiently form these compact associations. The presence of a γ′ chain, but not the carboxy terminal portions of either Aα chain are needed for complexation phenomena between pFN and γγ′-FI.

A novel experimental apparatus for investigating bubbly flows in a slot geometry.

Bubbly flows occur in a wide variety of industrial and environmental settings. While there is a broad literature that describes bubbly flow behavior in pipes and channels, flow in a high aspect ratio slot has received little attention. We describe the design and construction of a new experimental apparatus to investigate the processes associated with bubbly flows in a slot geometry. The apparatus is designed to perform scaled analog experiments to investigate the flow of bubbly magma through the sub-volcanic plumbing system, but it is sufficiently flexible to address many other flow scenarios. The main bubble column, which can be inclined up to 30° from the vertical, comprises a glass-walled slot 3 m wide and 2 m tall, with 3 cm gap width. A modular and flexible gas injection system allows the number, spacing, and diameter of the gas emission points to be varied, as well as gas injection flux, and a pumped recirculation system allows the concurrent liquid flow rate to be controlled and varied. A dedicated data acquisition system synchronizes high-speed videography with temperature and pressure data from different points in the apparatus. Preliminary data are presented to demonstrate the operation of the apparatus and to illustrate the types of fluid dynamic information that can be captured.

3-D numerical modelling of crustal polydiapirs with volume-of-fluid methods

SUMMARY Gravitational instabilities exert a crucial role on the Earth dynamics and in particular on its differentiation. The Earth’s crust can be considered as a multilayered fluid with different densities and viscosities, which may become unstable in particular with variations in temperature. With the specific aim to quantify crustal scale polydiapiric instabilities, we test here two codes, JADIM and OpenFOAM, which use a volume-of-fluid (VOF) method without interface reconstruction, and compare them with the geodynamics community code ASPECT, which uses a tracking algorithm based on compositional fields. The VOF method is well-known to preserve strongly deforming interfaces. Both JADIM and OpenFOAM are first tested against documented two and three-layer Rayleigh–Taylor instability configurations in 2-D and 3-D. 2-D and 3-D results show diapiric growth rates that fit the analytical theory and are found to be slightly more accurate than those obtained with ASPECT. We subsequently compare the results from VOF simulations with previously published Rayleigh–Bénard analogue and numerical experiments. We show that the VOF method is a robust method adapted to the study of diapirism and convection in the Earth’s crust, although it is not computationally as fast as ASPECT. OpenFOAM is found to run faster than, and conserve mass as well as JADIM. Finally, we provide a preliminary application to the polydiapiric dynamics of the orogenic crust of Naxos Island (Greece) at about 16 Myr, and propose a two-stages scenario of convection and diapirism. The timing and dimensions of the modelled gravitational instabilities not only corroborate previous estimates of timing and dimensions associated to the dynamics of this hot crustal domain, but also bring preliminary insight on its rheological and tectonic contexts.

Analog‐based post‐processing of the ALADIN‐LAEF ensemble predictions in complex terrain

AbstractThe main goal of this study is to assess the performance of the analog‐based post‐processing method applied to the Austrian ALADIN‐LAEF wind speed ensemble predictions through a set of sensitivity experiments. Evaluation of several analog‐based configurations using various meteorological variables as predictors is therefore conducted. The results of those experiments are compared to the ensemble model output statistics (EMOS) baseline model. The hypothesis further investigated is that using summarized measures, such as mean and standard deviation of an ensemble for several meteorological variables, is comparable to the analog post‐processing using all of the ensemble members. Results show that both analog‐based and EMOS experiments considerably improve the raw model forecast. Even though the improvement over raw model forecast is evident, large differences among nearby stations are noticed in the highly complex terrain. The processes at lower stations seem to be better represented by the raw model, which leads to a better input forecast to the post‐processing and a better overall result than for the mountain stations. The analog‐based method is overall comparable to or even outperforms the EMOS. Assessing the post‐processing performance for high wind speeds shows that the analog experiments can improve the raw forecast, exhibiting significantly higher skill than the EMOS. The difference among all analog experiments is less pronounced, especially the experiment using all of the raw model ensemble members and the one using summarized measures. Furthermore, it is demonstrated that the usage of summarized ensemble measures is an optimal way to improve the forecast skill, compared to the other analog‐based experiments and the EMOS model. Therefore, it is suggested that it is not necessary to increase the computational costs by using the full input spectrum of a raw probabilistic model, that is, all ALADIN‐LAEF members as predictors, as the summarized metric suffices.

Angiotensin II-mediated nondipping during sleep in healthy humans: effects on baroreflex function at subsequent daytime.

Blood pressure dipping at night is mediated by sleep-inherent, active downregulation of sympathetic vascular tone. Concomitantly, activity of the renin-angiotensin system is reduced, which might contribute to the beneficial effect of baroreflex downward resetting on daytime blood pressure homeostasis. To evaluate whether experimental nondipping mediated by angiotensin II during sleep would alter blood pressure and baroreflex function the next day in healthy humans, angiotensin-II or placebo (saline) was infused for a 7-h period at night, preventing blood pressure dipping in 11 sleeping normotensive individuals (5 males, balanced, crossover design). Baroreflex function was assessed about 1 h upon awakening and stop of infusion via microneurographic recordings of muscle sympathetic nerve activity (MSNA), showing that resting MSNA was significantly increased following angiotensin II nondipping compared with placebo (P = 0.029), whereas blood pressure and heart rate remained unchanged. Baroreflex sensitivity in response to vasoactive drug challenge was preserved, and neuroendocrine markers of fluid balance and electrolytes did not differ between conditions. Ambulatory blood pressure during subsequent daytime was not altered. Data were compared with analog experiments previously performed within the same subjects during awake daytime (ANCOVA). We conclude that angiotensin-II mediated nocturnal nondipping did not induce blood pressure elevation at subsequent daytime in healthy humans but was linked to increased vasoconstrictive sympathetic activity. This is in contrast to a prolonged increase in blood pressure in corresponding daytime experiments of the same individuals. Evidently, sleep strongly preserves normotensive blood pressure homeostasis in healthy humans.

Forearc Basin Stratigraphy Resulting From Syntectonic Sedimentation During Accretionary Wedge Growth: Insights From Sandbox Analog Experiments

AbstractForearc basin stratigraphy is expected to record a detailed history of the deformation and growth pattern of an accretionary wedge. However, the relationship between syntectonic basin sedimentation and growth of a wedge remains poorly understood, including how deformation of the wedge modifies the basin stratigraphy and how syntectonic sedimentation influences deformation of the wedge. This study reproduced accretionary wedges with and without syntectonic sedimentation by analog sandbox experiments. The results show that basin stratigraphy varied with changes of the growth pattern of the accretionary wedge. In the case that wedge growth was dominated by frontal accretion phase, the depositional area migrated trenchward. In contrast, underthrusting phase caused the sediment layers to be tilted landward and the depocenter to migrate landward. A prolonged underthrusting can result in combining a retrowedge basin with a wedge top basin and yield a wide area of accommodation space. The occurrence of two types of basin stratigraphy (trenchward and landward migration of the depocenter) reflects the two different types of deformation (frontal accretion phase and underthrusting phase), and these differences possibly depend on a contrast in strength of the basal shear resistance between the inner and outer parts of the wedge due to temporal and spatial variations of sedimentation on the wedge. A change in the magnitude of normal stress acting on the wedge base likely influenced the mode of deformation of the wedge. These results suggest that forearc basin stratigraphy is influenced by the growth pattern of accretionary wedges, which is itself affected by syntectonic sedimentation.

College students’ ambivalence over emotional expression and counselor’s directiveness: an analogue experiment on perceived therapeutic bond

ABSTRACT This experimental analogue study estimated how clients’ ambivalence over emotional expression (AEE) is linked to their perception of the therapeutic relationship and satisfaction with counseling, depending on the counselor’s communication style (i.e., directive versus non-directive). One hundred and seventy three college students were recruited using a research participation pool. Participants viewed videos of mock counseling sessions that demonstrated a counselor with a directive or non-directive communication style and were instructed to imagine they were the client in the video. Participants then rated their perceived therapeutic bond and satisfaction with the counseling in the video. Results from a moderated mediation effect analysis indicated that the counselor’s directiveness moderated the relationship between AEE and perceived therapeutic bond, which in turn mediated the relationship between AEE and counseling satisfaction. Specifically, participants with higher levels of AEE reported lower levels of satisfaction when they watched a non-directive style of therapy session, and this relationship was mediated by lower levels of perceived therapeutic bond. However, this association was not found for the directive style video. Implications and future directions for research and practice are discussed.

Ridged plains on Europa reveal a compressive past

Europa's young surface implies relatively recent resurfacing. Ridged plains, which make up >50% of Europa's surface, have not yet been fully analyzed for a potential formation mechanism. Because ridged plains dominate Europa's surface, this terrain is key to understanding how Europa has resurfaced and how the resurfacing mechanisms may have evolved through time. In this work, we create a new high-resolution topographic model and a two-layer physical analog model to investigate the formation of ridged plains. We find that the ridged plains most closely resemble the compressional physical analog experiments which generate folds. Specifically, the analog experiments with a brittle layer <1/16th the thickness of the underlying ductile-layer best explain the morphological observations of the ridged plains on Europa. Based on the scaling relationships, we find that at the time of the ridged plains formation, the brittle part of the ice shell of Europa's ice shell was ~200 m thick and the total ice-shell thickness, including both the ductile and brittle parts, was >~3000 m. Compared to the predicted current ice shell thickness, this would imply that Europa's ice-shell has thickened through the visible surface history.

Hydraulic Conductivity Behaviors of Karst Aquifer With Conduit-Fissure Geomaterials

This study uses laboratory analog and numerical experiments to simulate groundwater flow in karst aquifer and investigate the dimension-dependent hydraulic conductivity for groundwater flow in conduit-fissure medium. A coupled Darcy-Navier-Stokes mathematical model were developed to simulate groundwater flow transmitting process in karst aquifer. The Darcy law was used to model the flow in the fissure and the Navier-Stokes equations were used for the flow in the conduit. A laboratory analog which simulate the conduit-fissure domains of a karst aquifer was used to provide verification of proposed mathematical models and the calibration of numerical simulations. Numerical simulations were adopted to solved the coupled Darcy-Navier-Stokes mathematical model. The numerical simulation results for flow match well with laboratory experimental results. Furthermore, the hydraulic conductivity for fully developed flow was identified as four control factors (conduit diameter, fracture aperture, hydraulic pressure and strata dip angle) by the numerical simulations. A new empirical equation was proposed to derive the hydraulic conductivity. The significance of each factor on the hydraulic conductivity was evaluated by statistical analysis. The evidence shows that the conduit diameter and fracture aperture have the most influence on the hydraulic conductivity.

Criminal History, Sex, and Employment: Sex Differences in Ex‐Offender Hiring Stigma

AbstractCommunities across the United States integrate thousands of men and women coming out of jail or prison each year and studies suggest that over 75% of this population will reoffend within a decade of release. According to research, positive employment outcomes are linked to preventing recidivism; however, employers routinely check or inquire about criminal histories and discriminate against ex‐offender applicants. The current research focused on employer stigma against applicants with a criminal history with an online sample of adults (N = 296). The analogue experiment examined hiring decisions for Black versus White applicants with or without a criminal history in order to explore the effect of race and criminal history on hiring outcomes. As expected, participants were less likely to recommend applicants with a criminal history for employment, but the sex of the respondent moderated the differences in racial bias. Male hiring decision makers did not differentiate between applicants with or without a criminal history when presented with a White applicant but did show a stigma against Black ex‐offenders versus Black applicants with a clean criminal history. Female hiring decision makers showed the opposite pattern demonstrating no preference between Black applicants with or without a criminal history but preferring White applicants without a criminal record versus White ex‐offenders. These findings suggest that male and female hiring managers are differently affected by the presence of a criminal history depending on the race of the applicant and these differences if replicated have interesting policy implications.