Showing papers by "Saint Mary's University published in 2009"

Adaptive co-management for social–ecological complexity

Abstract: Building trust through collaboration, institutional development, and social learning enhances efforts to foster ecosystem management and resolve multi-scale society–environment dilemmas One emerging approach aimed at addressing these dilemmas is adaptive co-management This method draws explicit attention to the learning (experiential and experimental) and collaboration (vertical and horizontal) functions necessary to improve our understanding of, and ability to respond to, complex social–ecological systems Here, we identify and outline the core features of adaptive co-management, which include innovative institutional arrangements and incentives across spatiotemporal scales and levels, learning through complexity and change, monitoring and assessment of interventions, the role of power, and opportunities to link science with policy

Workplace empowerment, incivility, and burnout: impact on staff nurse recruitment and retention outcomes

Abstract: Aim The aim of this study was to examine the influence of empowering work conditions and workplace incivility on nurses’ experiences of burnout and important nurse retention factors identified in the literature. Background A major cause of turnover among nurses is related to unsatisfying workplaces. Recently, there have been numerous anecdotal reports of uncivil behaviour in health care settings. Method We examined the impact of workplace empowerment, supervisor and coworker incivility, and burnout on three employee retention outcomes: job satisfaction, organizational commitment, and turnover intentions in a sample of 612 Canadian staff nurses. Results Hierarchical multiple linear regression analyses revealed that empowerment, workplace incivility, and burnout explained significant variance in all three retention factors: job satisfaction (R2 = 0.46), organizational commitment (R2 = 0.29) and turnover intentions (R2 = 0.28). Empowerment, supervisor incivility, and cynicism most strongly predicted job dissatisfaction and low commitment (P < 0.001), whereas emotional exhaustion, cynicism, and supervisor incivility most strongly predicted turnover intentions. Conclusions In our study, nurses’ perceptions of empowerment, supervisor incivility, and cynicism were strongly related to job satisfaction, organizational commitment, and turnover intentions. Implications for nursing management Managerial strategies that empower nurses for professional practice may be helpful in preventing workplace incivility, and ultimately, burnout.

Broad line emission from iron K- and L-shell transitions in the active galaxy 1H 0707-495.

Abstract: The emission line arising from a transition of an electron from the iron K shell to the ground state (the K line) is prominent in the reflection spectrum of the hard X-ray continuum irradiating dense accreting matter around a black hole. The corresponding iron L-line emission should be detectable when iron abundance is high. That's the theory, and now broad iron L-line emission has been observed, together with the broad K line in the narrow-line Seyfert galaxy 1H0707. There is a reverberation lag of about 30 s between the direct X-ray continuum and its reflection from matter falling into the hole, a timescale comparable to the light-crossing time of the innermost radii around a supermassive black hole. This discovery opens a window on events close to the black hole event horizon in these objects. Emission arising from a transition of an electron from the iron K shell to the ground state (the K line) is prominent in the reflection spectrum created by the hard X-ray continuum irradiating the dense accreting matter around a black hole. Here the presence of both iron K and L emission is reported in the spectrum of the active galaxy 1H 0707-495. There is a 'reverberation lag' with a timescale comparable to the light-crossing time of the innermost radii around a supermassive black hole. Since the 1995 discovery of the broad iron K-line emission from the Seyfert galaxy MCG–6-30-15 (ref. 1), broad iron K lines have been found in emission from several other Seyfert galaxies2, from accreting stellar-mass black holes3 and even from accreting neutron stars4. The iron K line is prominent in the reflection spectrum5,6 created by the hard-X-ray continuum irradiating dense accreting matter. Relativistic distortion7 of the line makes it sensitive to the strong gravity and spin of the black hole8. The accompanying iron L-line emission should be detectable when the iron abundance is high. Here we report the presence of both iron K and iron L emission in the spectrum of the narrow-line Seyfert 1 galaxy9 1H 0707-495. The bright iron L emission has enabled us to detect a reverberation lag of about 30 s between the direct X-ray continuum and its reflection from matter falling into the black hole. The observed reverberation timescale is comparable to the light-crossing time of the innermost radii around a supermassive black hole. The combination of spectral and timing data on 1H 0707-495 provides strong evidence that we are witnessing emission from matter within a gravitational radius, or a fraction of a light minute, from the event horizon of a rapidly spinning, massive black hole.

The Impact of Brand Commitment on Loyalty to Retail Service Brands

Abstract: This paper incorporates the developing body of literature in relationship marketing to the study of brand loyalty. Relationship marketing literature has established that customer commitment is a central, complex construct consisting of at least an affective component and a continuance component. This study examined the extent to which affective and continuance commitment serve as mediators of the brand satisfaction—loyalty intentions relationship. The study found that, in two retail service brand settings, the two components of commitment fully mediate the relationship between brand satisfaction and both repurchase intentions and advocacy intentions. In addition, the study found that affective commitment to the brand was strongly and positively related to both repurchase intentions for the brand and willingness to act as an advocate on behalf of the brand. Continuance commitment was at best only weakly but positively related to repurchase intentions, but negatively related to advocacy intentions for the brand. Resume Le present article combine les publications de plus en plus nombreuses relatives au marketing cible et l'etude de la fidelite a la marque. Les publications relatives au marketing cible ont etabli que l'engagement du client est un concept central et complexe qui comprend au moins une composante affective et une composante de continuation. Cette etude examine dans quelle mesure l'engagement affectif et l'engagement de continuation mediatisent la satisfaction par rapport a la marque—rapport d'intentions de fidelite. L'etude revele que dans deux contextes de service de detail de marque, les deux composantes d'engagement mediatisent completement le rapport entre la satisfaction par rapport a la marque d'une part, les intentions de rachat et les intentions de promotion d'autre part. Par ailleurs, l'engagement affectif a la marque est fortement et positivement relie aux intentions de rachat de la marque et a la volonte de recommander et de defendre la marque. L'engagement de continuation est au mieux relie uniquement, faiblement mais positivement aux intentions de rachat. Cependant, il est negativement relie aux intentions de recommandation pour la marque.

Predicting workplace aggression and violence.

Abstract: Consistent with the relative recency of research on workplace aggression and the considerable media attention given to high-profile incidents, numerous myths about the nature of workplace aggression have emerged. In this review, we examine these myths from an evidence-based perspective, bringing greater clarity to our understanding of the predictors of workplace aggression. We conclude by pointing to the need for more research focusing on construct validity and prevention issues as well as for methodologies that minimize the likelihood of mono-method bias and that strengthen the ability to make causal inferences.

Safety leadership: A longitudinal study of the effects of transformational leadership on safety outcomes

Abstract: Transformational leadership based interventions were assessed using a pre-test, post-test, and control group design. Leaders (N=54) from 21 long-term health care organizations were randomly assigned to general transformational leadership training, safety-specific transformational leadership training, or a control group. Multivariate analysis of variance (MANOVA) showed that leadership training resulted in significant effects on manager post-training ratings of safety attitudes, intent to promote safety, and self-efficacy. The effects of leadership training on employee (N=115) perceptions of leader safety-specific transformational leadership, safety climate, safety participation, safety compliance, safety-related events and, injuries were also assessed. Multivariate analysis of covariance (MANCOVA), with the pre-test scores as the covariates, showed that leadership training resulted in significant effects on the safety-specific transformational leadership and safety climate outcomes.

Human dimensions of Marine Protected Areas

Abstract: Charles, A., and Wilson, L. 2009. Human dimensions of Marine Protected Areas. - ICES Journal of Marine Science, 66: 6-15.Planning, implementing, and managing Marine Protected Areas (MPAs) requires that attention be paid not only to the biological and oceanographic issues that influence the performance of the MPA, but equally to the human dimensions: social, economic, and institutional considerations that can dramatically affect the outcome of MPA implementation. This paper explores ten human dimensions that are basic to the acceptance and ultimate success of MPAs: objectives and attitudes, “entry points” for introducing MPAs, attachment to place, meaningful participation, effective governance, the “people side” of knowledge, the role of rights, concerns about displacement, MPA costs and benefits, and the bigger picture around MPAs. These people-orientated factors and their impact on the success and effectiveness of MPAs are examined in relation to experiences with MPAs globally, and in relation to two Canadian examples specifically, one coastal (Eastport, Newfoundland) and the other offshore (the Gully, Nova Scotia).

Flow at work: An experience sampling approach

Abstract: One of the core constructs of the positive psychology movement is that of ‘flow’, or optimal experience. The current study investigated the relationship between ‘flow’, the core job dimensions, and subjective well-being (SWB), as well as distinguishing between the state and trait components of flow. Experience sampling methodology (ESM) was used to track 40 architectural students over a 15 week semester while they engaged in studio work. Hierarchical linear modelling (HLM) indicated that 74% of the variance in flow was attributable to situational characteristics compared to dispositional factors. Results also indicated that academic work that was high in skill variety and autonomy was associated with flow. Flow was found to be correlated with positive mood. Cross-lagged regression analysis showed that momentary flow was predictive of momentary mood and not vice versa. The strengths and limitations of using ESM to study subjective work experiences and well-being are discussed, as well as the implications of the study of flow or optimal experience for industrial/organizational psychology.

Plant species diversity and environmental heterogeneity: spatial scale and competing hypotheses

Abstract: Questions: What is the observed relationship between plant species diversity and spatial environmental heterogeneity? Does the relationship scale predictably with sample plot size? What are the relative contributions to diversity patterns of variables linked to productivity or available energy compared to those corresponding to spatial heterogeneity? Methods: Observational and experimental studies that quantified relationships between plant species richness and within-sample spatial environmental heterogeneity were reviewed. Effect size in experimental studies was quantified as the standardized mean difference between control (homogeneous) and heterogeneous treatments. For observational studies, effect sizes in individual studies were examined graphically across a gradient of plot size (focal scale). Relative contributions of variables representing spatial heterogeneity were compared to those representing available energy using a response ratio. Results: Forty-one observational and 11 experimental studies quantified plant species diversity and spatial environmental heterogeneity. Observational studies reported positive species diversity-spatial heterogeneity correlations at all points across a plot size gradient from ∼1.0 × 10−1 to ∼1.0 × 1011 m2, although many studies reported spatial heterogeneity variables with no significant relationships to species diversity. The cross-study effect size in experimental studies was not significantly different from zero. Available energy variables explained consistently more of the variance in species richness than spatial heterogeneity variables, especially at the smallest and largest plot sizes. Main conclusions: Species diversity was not related to spatial heterogeneity in a way predictable by plot size. Positive heterogeneity-diversity relationships were common, confirming the importance of niche differentiation in species diversity patterns, but future studies examining a range of spatial scales in the same system are required to determine the role of dispersal and available energy in these patterns.

Agrarian change and peasant studies: changes, continuities and challenges – an introduction

Abstract: Agrarian transformations within and across countries have been significantly and dynamically altered during the past few decades compared to previous eras, provoking a variety of reactions from rural poor communities worldwide. The changed and changing agrarian terrain has also influenced recent rethinking in critical inquiry into the nature, scope, pace and direction of agrarian transformations and development. This can be seen in terms of theorising, linking with development policy and politics, and thinking about methodologies. This collection of essays on key perspectives, frameworks and methodologies is an effort to contribute to the larger rethinking. The following paper introduces the collection.

No hay ganancia en la milpa: the agrarian question, food sovereignty, and the on-farm conservation of agrobiodiversity in the Guatemalan highlands

Abstract: Although they receive little recognition for their contribution, peasant farmers in the global South play a fundamental role in securing the long-term global food supply. Via their self-sufficient agricultural practices, they cultivate the crop genetic diversity that enables food crops to adapt to changing environmental conditions. In this paper I draw upon empirical data from the Guatemalan center of agricultural biodiversity to investigate the concern that market expansion will displace peasant agriculture and undermine a cornerstone of the global food supply. I find that even though peasants' livelihoods involve multiple forms of market provisioning, they also engage in a Polanyian ‘double movement’ to protect their subsistence-oriented agricultural practices from the potentially deleterious effects of markets. I also investigate the so-called ‘agrarian question’ about the effects of market expansion on the viability of peasant agriculture, finding that although new forms of market provisioning are lik...

Mediating, Interactive, and Non-linear Effects in Service Quality and Satisfaction with Services Research

Abstract: This study examines a number of different hypotheses about the relationship between service quality and satisfaction with services and some important loyalty-related consequences of these constructs. The study confirms the general position in the service quality literature that satisfaction mediates the relationship between service quality and switching intentions, advocacy intentions, and willingness to pay more for the service. In particular, satisfaction is a strong mediator of the effects of service quality on customer retention. The study also finds good support for the existence of a non-linear relationship between satisfaction and these loyalty intentions. The nature of this non-linear relationship is such that the effect of satisfaction on these loyalty-related intentions is more positive at higher levels of satisfaction than it is at lower levels of satisfaction. This is consistent with emerging findings on the nature and consequences of customer delight. Resume Cette etude examine un certain nombre de differentes hypotheses concernant le rapport entre la qualite de service et la satisfaction des clients, et passe en revue quelques consequences importantes des ces hypotheses qui illuminent la loyaute des consommateurs envers produits et services. L'etude confirme la validite de la theorie dominante de la qualite de service, a savoir que la satisfaction reglemente le rapport entre la qualite de service et l'intention de commuter de service, comme entre la propensite de recommander un produit ou service et la volonte de supporter un prix plus eleve pour le meme service. En particulier, la satisfaction regit les standards de la qualite de service et la retention de la clientele. L'etude confirme egalement l'existence d'un rapport non-lineaire entre la satisfaction et la fidelite. Ce rapport indique que l'effet de la satisfaction sur la fidelite est proportionellement plus fort a des niveaux de satisfaction plus eleve qu'a des niveaux plus bas. Cette tendance par ailleurs est conforme a d'autres etudes recentes sur la nature et les consequences de la satisfaction des clients.

Development strategies and rural development: exploring synergies, eradicating poverty

Abstract: This essay reviews some of the main interpretations in development studies on agriculture's contribution to economic development It explores the relationship between agriculture and industry as well as between the rural and urban sectors in the process of development These issues are discussed by analysing the so-called ‘Soviet industrialisation debate’, the ‘urban bias’ thesis, the development strategies pursued in East Asia and Latin America from a comparative perspective, the impact of neoliberal policies on rural–urban relations and the ‘agriculture-for-development’ proposal of the World Development Report 2008 The main argument arising from analysing these issues is that a development strategy which creates and enhances the synergies between agriculture and industry and goes beyond the rural–urban divide offers the best possibilities for generating a process of rural development able to eradicate rural poverty

One-Neutron Removal Measurement Reveals O-24 as a New Doubly Magic Nucleus

Abstract: The first measurement of the momentum distribution for one-neutron removal from O-24 at 920A MeV performed at GSI, Darmstadt is reported. The observed distribution has a width (FWHM) of 99 +/- 4 MeV/c in the projectile rest frame and a one-neutron removal cross section of 63 +/- 7 mb. The results are well explained with a nearly pure 2s(1/2) neutron spectroscopic factor of 1.74 +/- 0.19 within the eikonal model. This large s-wave probability shows a spherical shell closure thereby confirming earlier suggestions that O-24 is a new doubly magic nucleus.

Do multiple large shareholders play a corporate governance role? evidence from east asia

Abstract: We examine the governance role of multiple large shareholder structures (MLSS) to determine their valuation effects in a sample of 1,252 publicly traded firms from nine East Asian economies. We find that the presence, number, and size of multiple large shareholders are associated with a significant valuation premium. Our results also show that the identity of MLSS influences corporate value and that the valuation effects of MLSS are more pronounced in firms with greater agency costs. Our results imply that MLSS play a valuable monitoring role in curbing the diversion of corporate resources.

Real Estate for the Long Term: The Effect of Return Predictability on Long-Horizon Allocations

Abstract: We examine how the predictability of real estate returns affects the risk of, and optimal allocations to, real estate for investors of differing investment horizons. Returns to direct real estate are mean reverting, and risk decreases with horizon. This is driven by a tendency for property transaction prices to overshoot inflation. Mean reversion in real estate returns is weaker than that of equities, resulting in real estate having similar risk to equities for long-term investors. However, optimal portfolios have large allocations to direct real estate at all horizons, and the allocation increases with horizon. Finally, we find that real estate investment trusts are a redundant asset class for investors with access to direct real estate as an asset class, but they do have a role in optimal allocations when direct property investment is not feasible.

Characteristics of the Galaxy according to Cepheids

Abstract: Classical and Type II Cepheids are used to reinvestigate specific properties of theGalaxy.A new TypeII reddening-freeCepheid distance parameterizationis formulatedfrom LMC Cepheids (OGLE), with uncertainties typically no larger than 5–15%. Adistance to the Galactic centre of R 0 = 7.8 ± 0.6 kpc is derived from the mediandistance to Type II Cepheids in the bulge (OGLE), R 0 = 7.7±0.7 kpc from a distanceto the near side of the bulge combined with an estimated bulge radius of 1.3 ± 0.3kpc derived from planetary nebulae. The distance of the Sun from the Galactic planeinferred from classical Cepheid variables is Z⊙ = 26 ± 3 pc, a result dependent onthe sample’s distance and direction because of the complicating effects of Gould’sBelt and warping in the Galactic disk. Classical Cepheids and young open clustersdelineate consistent and obvious spiral features, although their characteristics do notmatchconventionalpictures ofthe Galaxy’sspiralpattern.The Sagittarius-Carinaarmis confirmed as a major spiral arm that appears to originate from a different Galacticregion than suggested previously. Furthermore, a major feature is observed to emanatefrom Cygnus-Vulpecula and may continue locally near the Sun. Significant concernsrelated to the effects of metallicity on the VI-based reddening-free Cepheid distancerelations used here are allayed by demonstrating that the computed distances to theGalactic centre, and to several globular clusters (M54, NGC 6441, M15, and M5) andgalaxies (NGC 5128 and NGC 3198) which likely host Type II Cepheids: agree withliterature results to within the uncertainties. An additional empirical test is proposedto constrain any putative metallicity dependence of Cepheid distance determinationsthrough forced matches of distance estimates to a particular galaxy using both TypeII and classical Cepheids.Key words: stars: variables: Cepheids—Galaxy: fundamental parameters—Galaxy:structure.

Ionizing radiation from z=4-10 galaxies

Abstract: We compute the escape of ionizing radiation from galaxies in the redshift interval z=4-10, i.e., during and after the epoch of reionization, using a high-resolution set of galaxies, formed in fully cosmological simulations. The simulations invoke early, energetic feedback, and the galaxies evolve into a realistic population at z=0. Our galaxies cover nearly four orders of magnitude in masses (10^{7.8}-10^{11.5}\msun) and more than five orders in star formation rates (10^{-3.5}-10^{1.7}\msun\yr^{-1}), and we include an approximate treatment of dust absorption. We show that the source-averaged Lyman-limit escape fraction at z=10.4 is close to 80% declining monotonically with time as more massive objects build up at lower redshifts. Although the amount of dust absorption is uncertain to 1-1.5 dex, it is tightly correlated with metallicity; we find that dust is unlikely to significantly impact the observed UV output. These results support reionization by stellar radiation from low-luminosity dwarf galaxies and are also compatible with Lyman continuum observations and theoretical predictions at z\sim3-4.

The influence of female attractiveness on competitor derogation

Abstract: Female competitor derogation has been found to involve evaluations of facial attrac- tiveness, such that women are more likely to derogate other women when they are most fertile (FISHER 2004). However, the ultimate purpose of this derogation remains unknown. In this article, we explore the possibility that women's derogations of rivals will influence potential mates, such that derogatory comments cause men to lower their attractiveness judgments of the rivals. More- over, given that attractive women should be more preferred as mates by men, we investigate how a woman's facial attractiveness can affect her ability to influence men's perceptions. Our results indicate that the type of statements one makes significantly influences ratings of attractiveness, and that derogations by an attractive woman are more effective in their ability to influence men's evaluations of female facial attractiveness than are derogations by an unattractive woman. These effects do not hold for women, who are not significantly swayed by the attractiveness of the de- rogator. Several directions for future research are presented.

Lyα Radiative Transfer in Cosmological Simulations Using Adaptive Mesh Refinement

Abstract: A numerical code for solving various Ly{alpha} radiative transfer (RT) problems is presented. The code is suitable for an arbitrary, three-dimensional distribution of Ly{alpha} emissivity, gas temperature, density, and velocity field. Capable of handling Ly{alpha} RT in an adaptively refined grid-based structure, it enables detailed investigation of the effects of clumpiness of the interstellar (or intergalactic) medium. The code is tested against various geometrically and physically idealized configurations for which analytical solutions exist, and subsequently applied to three different simulated high-resolution 'Lyman-break galaxies', extracted from high-resolution cosmological simulations at redshift z = 3.6. Proper treatment of the Ly{alpha} scattering reveals a diversity of surface brightness (SB) and line profiles. Specifically, for a given galaxy the maximum observed SB can vary by an order of magnitude, and the total flux by a factor of 3-6, depending on the viewing angle. This may provide an explanation for differences in observed properties of high-redshift galaxies, and in particular a possible physical link between Lyman-break galaxies and regular Ly{alpha} emitters.

Rough Cluster Quality Index Based on Decision Theory

Abstract: Quality of clustering is an important issue in application of clustering techniques. Most traditional cluster validity indices are geometry-based cluster quality measures. This paper proposes a cluster validity index based on the decision-theoretic rough set model by considering various loss functions. Experiments with synthetic, standard, and real-world retail data show the usefulness of the proposed validity index for the evaluation of rough and crisp clustering. The measure is shown to help determine optimal number of clusters, as well as an important parameter called threshold in rough clustering. The experiments with a promotional campaign for the retail data illustrate the ability of the proposed measure to incorporate financial considerations in evaluating quality of a clustering scheme. This ability to deal with monetary values distinguishes the proposed decision-theoretic measure from other distance-based measures. The proposed validity index can also be extended for evaluating other clustering algorithms such as fuzzy clustering.

Secular evolution of viscous and self-gravitating circumstellar discs

Abstract: We add the effect of turbulent viscosity via the α-prescription to models of the self-consistent formation and evolution of protostellar discs Our models are non-axisymmetric and are carried out using the thin-disc approximation Self-gravity plays an important role in the early evolution of a disc, and the later evolution is determined by the relative importance of gravitational and viscous torques In the absence of viscous torques, a protostellar disc evolves into a self-regulated state with the Toomre parameter Q ∼ 15 - 20, non-axisymmetric structure diminishing with time and maximum disc-to-star mass ratio ξ = 014 We estimate an effective viscosity parameter α eff associated with gravitational torques at the inner boundary of our simulation to be in the range 10 -4 -10 -3 during the late evolution The addition of viscous torques with a low value a = 10 -4 has little effect on the evolution, structure and accretion properties of the disc, and the self-regulated state is largely preserved A sequence of increasing values of a results in the discs becoming more axisymmetric in structure, being more gravitationally stable, having greater accretion rates, larger sizes, shorter lifetimes and lower disc-to-star mass ratios For a = 10 -2 , the model is viscous-dominated, and the self-regulated state largely disappears by late times The axisymmetry and low surface density of this model may contrast with observations and pose problems for planet formation models The use of α = 01 leads to very high disc accretion rates and rapid (within 2 Myr) depletion of the disc, and seems even less viable observationally Furthermore, only the non-viscous-dominated models with low values of a = 10 -4 -10 -3 can account for an early phase of quiescent low accretion rate M ∼ 10 -8 M ⊙ yr -1 (interspersed with accretion bursts) that can explain the recently observed Very Low luminosity Objects (VeLLOs) We also find that a modest increase in disc temperature caused by a stiffer barotropic equation of state (y = 167) has little effect on the disc accretion properties averaged over many disc orbital periods (∼10 4 yr), but can substantially influence the instantaneous mass accretion rates, particularly in the early embedded phase of disc evolution

Late Cretaceous and Cenozoic fossil dinoflagellates and other palynomorphs from the Scotian Margin, offshore eastern Canada

Abstract: Synopsis Palynomorphs, especially dinoflagellate cysts (dinocysts), have been at the forefront of research carried out on Mesozoic‐Cenozoic sediments on the Scotian Margin over the last 30–40 years: this research has been driven by the need to develop a stratigraphical framework to better understand the region's petroleum systems. To support the compilation of a detailed event strati‐graphical scheme for the Late Cretaceous to Cenozoic of the margin, emphasising dinocysts but with information from other fossil groups and non‐biostratigraphical data, there is a need to formalise the dinocyst taxonomy. In this paper, we fulfill this need by illustratingand, where appropriate, describing and discussing taxa used in our event biostratigraphical scheme. The following taxa (dinocysts except where indicated) are new: Areoligeracircumsenonensis,Axiodinium,Axiodiniumprearticulatum, Cordosphaeridium delimurum, Glaphyrocysta extensa, Hafniasphaera delicata, Impletosphaeridium capitatum, Mendicodinium robustum (valid...

Thermal Conductivity of Standard Sands. Part I. Dry-State Conditions

Abstract: A comprehensive thermal conductivity (λ) database of three dry standard sands (Ottawa C-109, Ottawa C-190, and Toyoura) was developed using a transient line heat source technique. The database contains λ data representing a variety of soil compactions and temperatures (T) ranging from 25 °C to 70 °C. The tested standard sands, due to their repeatable physical characteristics, can be used as reference materials for validation of thermal probes applied to similar dry granular materials. The measured data show an increasing trend of thermal conductivity at dryness (λdry) against T in spite of declining quartz λ with T. The air content (porosity) controls the λ of dry sands by acting as a very effective thermal insulator around solid soil particles. As a result, a diminutive increase of λdry with T is driven by increasing λ of air. The experimental λ data of dry sands were exceptionally well predicted by de Vries and Woodside–Messmer models, and also by a thermal conductance model, a product of λ of solids and the thermal conductance factor.