805 research outputs found

    The why's the limit: curtailing self-enhancement with explanatory introspection

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    Self-enhancement is linked to psychological gains (e.g., subjective well-being, persistence in adversity) but also to intrapersonal and interpersonal costs (e.g., excessive risk taking, antisocial behavior). Thus, constraints on self-enhancement may sometimes afford intrapersonal and interpersonal advantages. We tested whether explanatory introspection (i.e., generating reasons for why one might or might not possess personality traits) constitutes one such constraint. Experiment 1 demonstrated that explanatory introspection curtails self-enhancement. Experiment 2 clarified that the underlying mechanism must (a) involve explanatory questioning rather than descriptive imagining, (b) invoke the self rather than another person, and (c) feature written expression rather than unaided contemplation. Finally, Experiment 3 obtained evidence that an increase in uncertainty about oneself mediates the effect

    Immobile Water Content and Mass Exchange Coefficient of a Field Soil

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    Determining the preferential flow characteristics of a soil is important because agrichemicals can contaminate groundwater via preferential flow pathways. A model that predicts solute transport due to preferential flow is the mobile-immobile solute transport model, which partitions the total water content (θ, m3 m−3) into a mobile fraction (θm) and an immobile fraction (θim). Recently, an in situ method was proposed for determining the mobile-immobile model parameters of θim and mass exchange coefficient (α) between the fractions by using a tension infiltrometer to apply a series of four fluorobenzoate tracers. The objective of this study was to test the in situ technique at 47 sites along a transect in a ridge-till corn (Zea mays L.) field of Nicollet soil (fine-loamy, mixed, mesic Aquic Hapludoll). The immobile fraction (θim /θ) ranged from 0.394 to 0.952 with a median of 0.622. The mass exchange coefficient ranged from 0.000237 to 0.00481 min−1 with a median of 0.00123 min−1. These values are similar in magnitude and range to values reported by other investigators, and they follow the same relationships. The values of θim/θ and α along the transect indicated no obvious spatial trends or spatial correlations. Significant linear correlations did exist between α and soil water flux, α and θim, and θ and θim

    Soil Water Infiltration as Affected by the Use of the Paraplow

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    DOUBLE-RING infiltration measurements were made during the corn growing season to determine the effect of various tillage systems on 1- and 30-min cumulative infiltration at three locations in Iowa. The Paraplow*, a newly introduced tillage tool in North America, which loosens the soil but does not invert it, was compared with moldboard-plow, chisel-plow, and no-tillage treatments. The Paraplow treatment gave the highest 1- and 30-min cumulative infiltration throughout the growing season. Similar bulk densities to a depth of 10 cm were observed for all the tillage treatments except for immediately after fall tillage at one site where moldboard-plowed and chisel-plowed soils had the lowest bulk densities. No-tillage and Paraplow treatment plots generally had greater moisture contents in the top 10 cm. Deep, surface connected cracks enhanced soil water infiltration considerably, and residue cover, particularly on the surface of no-tillage and Paraplow treatment plots, seemed to prevent surface sealing that would restrict soil water infiltration

    Comparing Field Methods that Estimate Mobile–Immobile Model Parameters

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    Recent studies have used field techniques that estimate soil hydraulic and solute transport parameters. These methods utilize a tension infiltrometer to infiltrate either a single tracer or a series of tracers in order to estimate immobile water content (θim) and mass exchange coefficient (α) of the mobile–immobile solute transport model. The objective of this study was to compare two single tracer methods (basic and variance) with one multiple tracer method for estimating θim and α from data obtained on the same field soil location. Hydraulic conductivity (K(h 0)) was also estimated using these methods. Research was done at five interrow sites in a ridge-tilled corn (Zea mays L.) field, and the soil was mapped as a Nicollet series (fine-loamy, mixed, superactive, mesic, Aquic Hapludoll). The values of θim and α estimated by the multiple tracer method compared well with previously measured values using the same technique on the same field. The θim values for the multiple tracer technique were larger than values derived from the basic single tracer technique. The basic single tracer technique did not take into consideration a mass exchange between θim and the mobile water domain (θm). The α values were less variable for the multiple tracer method than for the single tracer-variance method. Values of immobile water fraction (θim/θ) for the multiple and basic single tracer techniques ranged from 0.30 to 0.52 and from 0.24 to 0.35, respectively. The values of α for the multiple and single tracer-variance techniques ranged from 0.06 to 0.9 d−1 and from 0.03 to 60 d−1, respectively. The volumetric water content (θ) changed considerably over the course of the experiment for the estimation of α using the single tracer-variance method; thus, the assumptions of this technique were compromised. The measured values of K(h 0) at the five sites ranged from 0.47 to 1.66 μm s−1 There was evidence that the basic single tracer method underestimated θim and overestimated θm, because this method considers α = 0 during the tracer application

    Temperature Dependence of Water Retention Curves for Wettable and Water-Repellent Soils

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    The capillary pressure (ψ) in unsaturated porous media is known to be a function of temperature (T). Temperature affects the surface tension (σ) of the pore water, but possibly also the angle of contact (γ). Because information on the temperature dependence of γ in porous media is rare, we conducted experiments with three wettable soils and their hydrophobic counterparts. The objectives were (i) to determine the temperature dependence of the water retention curve (WRC) for wettable and water-repellent soils, (ii) to assess temperature effects on the apparent contact angle γA derived from those WRCs, and (iii) to evaluate two models (Philip-de Vries and Grant-Salehzadeh) that describe temperature effects on ψ. Columns packed with natural or hydrophobized soil materials were first water saturated, then drained at 5, 20, and 38°C, and rewetted again to saturation. Capillary pressure and water content, θ, at five depths in the columns were measured continuously. The observations were used to determine the change in γA with T, as well as a parameter β0 that describes the change in ψ with T It was found that the Philip-de Vries model did not adequately describe the observed relation between ψ and T A mean value for β0 of −457 K was measured, whereas the Philip-de Vries model predicts a value of −766 K. Our results seem to confirm the Grant-Salezahdeh model that predicts a temperature effect on γA For the sand and the silt we studied, we found a decrease in γA between 1.0 to 8.5°, when the temperature was increased from 5 to 38°C. Both β0 and γA were only weak functions of θ. Furthermore, it seemed that for the humic soil under study, surfactants, i.e., the dissolution of soil organic matter, may compound the contact angle effect of the soil solids

    Parenting Narcissus: What are the links between parenting and narcissism

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    ABSTRACT Previous theorizing by clinical psychologists suggests that adolescent narcissism may be related to parenting practice

    Extended methodology for determining wetting properties of porous media

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    [1] Because most methods for assessing the wettability of porous materials are restricted in their applicability, we developed two new methods for measuring contact angles and particle surface energy. The proposed methods (the Wilhelmy plate method (WPM) and the modified capillary rise method (MCRM)) were tested on 24 soils. For comparison, the water drop penetration time test (WDPTT) and the sessile drop method (SDM) were also applied. It was found that advancing contact angles, measured either with WPM or MCRM, agreed well in the range of 0° to 142°. Sessile drop contact angles were within the domain enclosed by the range of advancing and receding contact angles as determined with WPM. WDPTT, however, was only sensitive in the narrow range of 85° to 115°. We conclude that both WPM and MCRM are reliable methods for determining contact angles and particle surface energy over a wide range of porous material wettabilities

    Latent heat in soil heat flux measurements

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    The surface energy balance includes a term for soil heat flux. Soil heat flux is difficult to measure because it includes conduction and convection heat transfer processes. Accurate representation of soil heat flux is an important consideration in many modeling and measurement applications. Yet, there remains uncertainty about what comprises soil heat flux and how surface and subsurface heat fluxes are linked in energy balance closure. The objective of this study is to demonstrate the presence of a subsurface latent heat sink, which must be considered in order to accurately link subsurface heat fluxes between depths near and at the soil surface. Measurements were performed under effectively bare surface conditions in a silty clay loam soil near Ames, IA. Soil heat flux was measured with heat-pulse sensors using the gradient heat flux approach at 1-, 3-, and 6-cm soil depths. Independent estimates of the daily latent heat sink were obtained by measuring the change of mass of microlysimeters. Heat flux measurements at the 1-cm depth deviated from heat flux measurements at other depths, even after calorimetric adjustment was made. This deviation was most pronounced shortly after rainfall, where the 1-cm soil heat flux measurement exceeded 400 W m−2. Cumulative soil heat flux measurements at the 1-cm depth exceeded measurements at the 3-cm depth by \u3e75% over a 7-day rain-free period, whereas calorimetric adjustment allowed 3- and 6-cm depth measurements to converge. Latent heat sink estimates from the microlysimeters accounted for nearly all of the differences between the 1- and 3-cm depth heat flux measurements, indicating that the latent heat sink was distributed between the 1- and 3-cm depths shortly after the rainfall event. Results demonstrate the importance of including latent heat when attempts are made to link or extrapolate subsurface soil heat flux measurements to the surface soil heat flux
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