The geomorphology at Adršpach-Teplice, Czech Republic is dominated by vertical-walled, fracture-controlled features including slot canyons, gorges and pillars. Surfaces of canyon walls in Adršpach are case-hardened and more resistant to erosion than the bulk of the sandstone, which appears to be fundamental to the formation and preservation of canyons. Core and whole rock samples from Adršpach-Teplice were analyzed in thin section, including SEM analysis with cathodo luminescence. XRF and XRD analyses indicated that silica case-hardened surfaces are chemically and mineralogically similar to the rock interior, while iron case-hardened surfaces have an increase in iron present at the surface as the mineral goethite. Permeability analysis indicates a decrease in porosity in case-hardened surfaces. The rock at Adršpach-Teplice is poorly cemented yet has the strength to maintain vertical faces because of a locked sand structure, which was formed by pressure solution. Fracture faces contain disaggregation and cataclastic bands that reduce porosity and increase strength. Case-hardening exists on fracture faces and other surfaces as either silica or iron. Silica case-hardening is ubiquitous in the area and consists of a slight increase in abundance of silica overgrowths and sometimes an increase in clay content. It can form on fresh surfaces in as little as five years, creating what is essentially a self-repairing material. Iron case-hardening is composed of goethite, is much less prevalent than silica case-hardening, and does not appear to be actively depositing. Lichens, fungi, and other biological material are present on case-hardened surfaces and may add to the strength of the material. The internal structure of the rock lends the strength to form and maintain the features seen at Adršpach-Teplice, while case-hardening helps to protect them from erosion.

Linear dunes are one of the most abundant and important features on the surface of Titan. We present a model for estimating the volume of dune sediment using the area coverage of Titan's sand seas along with dune widths, spacings, and heights. This helps to reveal local sediment transport and deposition. We refine global dune area estimates from Cassini SAR (Synthetic Aperture RADAR) of 20 million km2 or 24 ± 3% of Titan's surface based on ~50% Cassini RADAR global coverage. Additionally, the global area of sand seas is estimated from a joint analysis of Cassini SAR and ISS (Imaging Science Subsystem) images of 12.8 ± 2 million km2 or 15.4 ± 2.4% of Titan's surface. Also, we provide the first area measurements by sand sea, then describe a new method for estimation of the volume of dune sands across the sand seas based on imagery and measured dune characteristics (i.e., width, spacing, profile, and height) on Titan and in Earth's Namib Sand Sea. Our volume thickness map shows sand sea volumes of 3.8--7.9 x 104 km3 in Senkyo, 6.1--12.7 x 104 km3 in Belet, 5.3--11.0 x 104 km3 in Shangri-La, and also 5.3--11.0 x 104 km3 in Fensal and Aztlan Sand Seas. Our estimate for global dune sand volume is 206,000 km3 - 427,000 km3. The volume map identifies regional changes in sediment thickness implying local variations in transport and deposition and spatial variations in wind strength and direction. We show that dunes might be isolated to equatorial regions because of wind strength, topography, sediment supply, and humidity. Our preliminary map can be used as a tool to understand sediment transport and deposition to explain spatial variations in eolian sediment volume on Titan.

[pt] Nesta pesquisa, ensaios de caracterização e de permeabilidade foram realizados em uma amostra da Areia da Praia de Ipanema, RJ, tendo como ponto de partida a pesquisa realizada por Simões (2015). A caracterização incluiu granulometria por peneiramento, densidade relativa dos grãos (Gs), análise microscópica e avaliação dos índices de vazios mínimo e máximo por diferentes metodologias. Os ensaios de permeabilidade sob carga hidráulica constante foram realizados em um permeâmetro de parede flexível em corpos de prova moldados nos domínios de compacidades relativa fofo e compacto. A amostra é caracterizada como uma areia fina e média, mal graduada e uniforme, sendo constituída basicamente por grãos de quartzo, com densidade relativa (Gs) igual a 2,656. Quanto à forma, os grãos são subangulares a arredondados, com esfericidade igual a 0,7 e arredondamento igual a 0,5. Os valores obtidos de índice de vazios mínimo e máximo são, respectivamente, 0,435 e 0,760. No domínio de compacidade relativa (CR) fofo (CR da ordem de 30 por cento) foi medido um coeficiente de permeabilidade (k20 Graus C) de 2,0 x 10-2 cm/s, ao passo que no domínio compacto (CR da ordem de 80 por cento) foi medido um coeficiente de permeabilidade (k20 Graus C) de 1,2 x 10-2 cm/s, em média. Os resultados indicam ainda que a expressão proposta por Taylor (1948) que relaciona o coeficiente de permeabilidade (k) e e (3) / (1 + e) por uma reta que passa pela origem seja aplicável à Areia da Praia de Ipanema. / [en] In this research, characterization and permeability tests were performed on a sample of the Ipanema Beach Sand, RJ, considering the research carried out by Simões (2015) as the starting point. The characterization included grain size distribution by sieve analysis, specific gravity (Gs), microscopic analysis and evaluation of minimum and maximum void ratios by different methodologies. Constant head permeability tests were carried out on a flexible-wall permeameter on specimens molded in loose and dense states of relative density (Dr). The sample is characterized as a fine and medium sand, poorly graded and uniform, essentially comprised of quartz grains with specific gravity (Gs) equal to 2.656. Regarding the shape, the grains are subangular to rounded, with sphericity equal to 0.7 and roundness equal to 0.5. The values obtained for the minimum and maximum void ratios are 0.435 and 0.760, respectively. In the loose state (Dr of the order of 30 percent) an average value of permeability coefficient (k20 C Degrees) equal to 2.0 x 10-2 cm/s was measured, whereas in the dense state (Dr of the order of 80 percent) an average value of permeability coefficient (k20 C Degrees) equal to 1.2 x 10-2 cm/s was measured. The results indicate that the expression proposed by Taylor (1948), which relates the permeability coefficient (k) and e(3) / (1 + e) by a straight line that passes through the origin, applies to the Ipanema Beach Sand.

The Gulf of Maine is a dynamic ecosystem with rapidly warming sea surface temperatures (SSTs), therefore it is vital to understand how species interactions vary over time and space. In chapter two, I quantify and compare dietary differences among four tern species, across seven islands in the region, over a 32-year period. Multivariate statistical analyses were employed to discern spatial and temporal differences in foraging ecology. Findings suggest there are significant differences between species and islands; however, only three prey species comprise the majority of chick diet for all terns and islands. The reliance on only a few prey items led to narrow foraging niches, potentially increasing their vulnerability to climate change, fisheries practices, or other localized disturbances. The third chapter characterizes long-term trends across nesting islands, describes within-season dietary phenology, and quantifies how warming SSTs may influence diet. Over time there was a declining trend in the occurrence of hake and increasing amounts of sand lance. In addition, hake and sand lance occur with higher frequency earlier in the season, while butterfish and “other fish” showed the opposite trend. Furthermore, results indicated that the within-season decline of hake occurs more rapidly in years with earlier spring thermal transition dates potentially indicating a phenological shift. Finally, warming SSTs were found to be negatively correlated with hake and positively correlated with the “other fish” prey group. Given projections of further warming in the region, understanding how the diet of these seabirds may be impacted in crucial to their conservation.

The density of single grain states in static granular packings is derived from first principles for an idealized yet fundamental case. This produces the distribution of contact forces P_f(f) in the packing. Because there has been some controversy in the published literature over the exact form of the distribution, this dissertation begins by reviewing the existing empirical observations to resolve those controversies. A method is then developed to analyze Edwards' granular contact force probability functional from first principles. The derivation assumes Edwards' flat measure -- a density of states (DOS) that is uniform within the metastable regions of phase space. A further assumption, supported by physical arguments and empirical evidence, is that contact force correlations arising through the closure of loops of grains may be neglected. Then, maximizing a state-counting entropy results in a transport equation that can be solved numerically. For the present it has been solved using the "Mean Structure Approximation," projecting the DOS across all angular coordinates to more clearly identify its predominant features in the remaining stress coordinates. These features are: (1) the Grain Factor related to grain stability and strong correlation between the contact forces on the same grain, and (2) the Structure Factor related to Newton's third law and strong correlation between neighboring grains. Numerical simulations were then performed for idealized granular packings to permit a direct comparison with the theory, and the data including P_f(f) were found to be in excellent agreement. Where the simulations and theory disagree, it is primarily due to the coordination number Z because the theory assumes Z to be a constant whereas in disordered packings it is not. The form of the empirical DOS is discovered to have an elegant, underlying pattern related to Z. This pattern consists entirely of the functional forms correctly predicted by the theory, but with only slight parameter changes as a function of Z. This produces significant physical insight and suggests how the theory may be generalized in the future.

Titanium has been widely used for dental implants, and in particular, roughened titanium surfaces have provided a means for increasing bone apposition and strengthening the implant-to-bone interface. Finding a way to further increase osseointegration is important because there is a significant clinical benefit to patients if a stable anchor can be established instead of anchoring orthodontic hardware to the molars. In this study, the effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on the ability of temporary anchorage devices (TADs) to osseointegrate was investigated. The temporary anchorage devices (TADs) used in this study were manufactured from commercially pure titanium and divided into 2 types of treatments: (1) sandblasted and acid-etched (i.e. the control) and (2) sandblasted and acid-etched treated with Medtronic INFUSE® Bone Graft (recombinant human bone morphogenetic protein-2 placed on an absorbable collagen sponge). The implants were placed on the cranial bones of 10 adult male Sprague-Dawley rats. The rats were euthanized by carbon dioxide asphyxiation 6 weeks following surgery for histological examination and biomechanical testing. The results from visual inspection and biomechanical testing showed that the sandblasted and acid-etched TADs treated with rhBMP-2 promoted better osseointegration than TADs that were only sandblasted and acid-etched. Specifically, surface modified TADs treated with rhBMP-2 on bottom showed an increased surface coverage by bone and an increase in the adhesion strength at the TAD-to-bone interface.

Yes / In nature, environmental and geophysical flows frequently encounter submerged cylindrical bodies on a rough bed. The flows around the cylindrical bodies on the rough bed are very complicated as the flow field in these cases will be a function of bed roughness apart from the diameter of the cylinder and the flow velocity. In addition, the sand-bed roughness has different effects on the flow compared to the gravel-bed roughness due to differences in the roughness heights. Therefore, the main objective of this article is to compare the mean velocities and turbulent flow properties in the wake region of a horizontal bed-mounted cylinder over the sand-bed with that over the gravel-bed. Three experimental runs, two for the sand-bed and one for the gravel-bed with similar physical and hydraulic conditions, were recorded to fulfil this purpose. The Acoustic Doppler Velocimetry (ADV) probe was used for measuring the three-dimensional (3D) instantaneous velocity data. This comparative study shows that the magnitude of mean streamwise flow velocity, streamwise Reynolds normal stress, and Reynolds shear stress are reduced on the gravel-bed compared to the sand-bed. Conversely, the vertical velocities and vertical Reynolds normal stress are higher on the gravel-bed than the sand-bed. / The Author Ram Balachandar acknowledges the grant support from Natural Sciences and Engineering Research Council of Canada the author Jaan H. Pu acknowledges the grant support from the Hidden Histories of Environmental Science Project (at Seedgrant Stage) by the Natural Environment Research Council (NERC) and Arts and Humanities Research Council (AHRC), part of UK Research and Innovation (UKRI).

Yes / Utilizing seawater and sea-sand for producing ultra-high performance concrete (UHPC) can substantially reduce raw materials costs and alleviate the current freshwater and river sand resources shortage in coastal and marine areas. However, the corrosion risk to reinforcing fibers inside UHPC caused by chlorides in seawater and sea-sand cannot be ignored. In this study, a new type of sustainable UHPC composed of seawater and desalinated sea-sand (UHPSSC) reinforced with stainless profile, super-fine stainless wire (SSW) was developed. Its mechanical properties and chloride content were studied. The research results show that SSWs do not rust after immersion in seawater. The flexural and compressive strengths of UHPSSC incorporating 1.5% SSWs are 13.8MPa and 138.6MPa, respectively, and the flexural toughness of UHPSSC is increased by 428.9%, reaching the basic mechanical requirements of UHPC. The high specific surface area of SSW and enrichment of silica fume on its surface enhance the interfacial bond between fiber and matrix, further promoting the full play of the SSWs’ reinforcing mechanisms as proved by the decrease of the Ca/Si ratio at the SSW surface. The C-S-H gels with a high Ca/Si ratio within the ITZ as well as Friedel’s salt are conducive to immobilize chlorides, blocking the migration of chlorides through the matrix and further mitigating the risk of long-term chloride corrosion of SSWs. Overall, utilizing seawater and desalinated sea-sand in combination with SSWs can produce UHPC with improved strength and toughness, making it a suitable choice for applications where high durability and long-term mechanical performance is required.

No / A novel technique for the laboratory characterization of the frequency-dependent acoustic surface admittance of partly saturated samples of sands is presented. The technique is based on a standard laboratory de-watering apparatus coupled with a standard acoustic impedance tube. The dependence of the surface admittance on the degree of water saturation is investigated for two samples of sand with widely different flow resistivities. It is shown that a relatively small change (e.g., from 0% to 11% by volume) in the degree of water saturation can result in a much larger change (e.g., twofold) in the acoustic surface admittance. An empirical relationship is found between the peaks observed in the real part of admittance spectra for the low flow resistivity sand and the degree of water saturation. The data are compared with predictions of two widely used ground impedance models: a semiempirical single parameter model and a two parameter model. A modified two-parameter version of a single-parameter model is found to give comparable fit to the two-parameter model. However, neither model provides an accurate fit.

To achieve multiple learning objectives, the ideal preschool activity center should promote development across all domains, from adaptive to social-communicative. Though early childhood practitioners describe the sensory table as capable of doing so, empirical accounts stand in stark contrast and suggest that it is a non-social functional activity. The intent of the present investigation was to reconcile this distinct dichotomy through the systematic manipulation of four sensory table substances (sand, soil, rocks, and water) and provision sets that differed in realism to determine their effect on preschoolers' free play behavior. Preschoolers' play forms and social participation were observed at the sensory table as they used a novel surface, which was introduced weekly without repetition, and either a set of minimally structured objects or realistic toys. Preschoolers' play and social participation were indeed influenced by the arrangement of the table. The sand, water, and provision sets yielded the most salient effects. Sand pulled for more sophisticated cognitive and social play forms while water pulled for more rudimentary ones. Regarding provision sets, the highly structured toys pulled for the most mature cognitive play form while the minimally structured toys pulled for the most sophisticated social context. The highly structured toys, with realism that lent to specific themes, appear to have functioned as a thematic anchor and cultivated a greater occurrence of dramatic play as compared to the minimally structured objects, which pulled for more functional play. Conversely, the minimally structured toy set, containing objects that loosely represented realistic objects and/or were capable of multiple functions, fostered a greater amount of socialization through parallel, social, and social-constructive play. Aside from its motoric and adaptive value, findings from this investigation suggest that under certain ecological conditions the sensory table fosters the development of cognitive and social skills. Recommendations for early childhood education practitioners are provided.