Modeling of the Earth's gravity field using the New Global Earth Model (NEWGEM)

Traditionally, the global gravity field was described by representations based on the spherical harmonics (SH) expansion of the geopotential. The SH expansion coefficients were determined by fitting the Earth's gravity data as measured by many different methods including the use of artificial satellites. As gravity data have accumulated with increasingly better accuracies, more of the higher order SH expansion coefficients were determined. The SH representation is useful for describing the gravity field exterior to the Earth but is theoretically invalid on the Earth's surface and in the Earth's interior. A new global Earth model (NEWGEM) (KIM, 1987 and 1988a) was recently proposed to provide a unified description of the Earth's gravity field inside, on, and outside the Earth's surface using the Earth's mass density profile as deduced from seismic studies, elevation and bathymetric information, and local and global gravity data. Using NEWGEM, it is possible to determine the constraints on the mass distribution of the Earth imposed by gravity, topography, and seismic data. NEWGEM is useful in investigating a variety of geophysical phenomena. It is currently being utilized to develop a geophysical interpretation of Kaula's rule. The zeroth order NEWGEM is being used to numerically integrate spherical harmonic expansion coefficients and simultaneously determine the contribution of each layer in the model to a given coefficient. The numerically determined SH expansion coefficients are also being used to test the validity of SH expansions at the surface of the Earth by comparing the resulting SH expansion gravity model with exact calculations of the gravity at the Earth's surface

Vascular self-healing of a reinforced concrete beams under 4-point bending

Self-healing materials are inspired on self-healing capabilities of living organisms. For plants, animals and people, the vascular system that distributes nutrients to all parts of the organism is also key for the self-healing capability. In a concrete element, a self-healing approach with an incorporated vascular system possess advantages towards repeatable self-healing and controlled placement of the self-healing system in the areas of interest. This study presents such a vascular system, which is designed to be accessible from outside of the concrete beam. Both clay and inorganic phosphate cement are compared as materials for the vanes of this system. The specimen contain steel reinforcement and are tested by means of 4-point bending, in order to obtain realistic conditions. Ease of construction and placement are discussed. From the experiments it can be seen that repeatable selfhealing is possible, that the system is able to heal multiple cracks at the same time and that cracks can be sealed and mechanical properties restored

Social Housing and Homelessness Policies: reconciling social justice and social mix

First paragraph: Whilst housing policies already had a distinctive Scottish flavour even before devolution, the creation of the Scottish Parliament in 1999 has allowed further policy-divergence (see for example, Maclennan and O‟Sullivan 2008). As Kintrea (2006) highlights the firstREF term of the Scottish Parliament resulted in a number of high-level policy goals centred on social justice, social cohesion, economic competitiveness and empowerment. Both the policy documents and memorandums in circulation at this time highlighted that housing reform was, “to contribute to policy objectives that are broader and more fundamental than new arrangements for the delivery of housing services” (Kintrea 2006: 190). This chapter will focus its attention on the first two of these articulated goals: social justice and social cohesion, and in doing so illuminate the progress and contradictions that have characterised social housing and homelessness reforms in a devolved Scotland. Whilst social justice is concerned with equal opportunities and rights of access to social rented housing, social cohesion relates to social mix and is intimately connected to wider public policy debates around social capital, social networks and the most appropriate solution to tackling concentrations of poverty

Comparison of Skin Cancer Knowledge, Attitude, and Protective Behavior in African American Students in East and West Coasts

Purpose and Background: African Americans, in comparison to other ethnic groups, are often diagnosed with melanoma at advanced stages, resulting in low survival rates. One of the strongest risk factors for all types of skin cancer is exposure to UV radiation from the sun. UV ray intensity is associated with latitude; lower latitudes have stronger UV rays than higher latitudes. This study examines and compares the knowledge, attitude, and protective behavior toward skin cancer among United States African American college students who live in two different latitudes, Maryland and southern California. Methods: We surveyed 360 African American students from two major universities in southern California and Maryland. Students were asked to fill out questionnaires that assessed their knowledge, attitude, and protective behavior regarding sun exposure. Results: More African American students from Maryland knew the direct link between UV/sun radiation exposure and the occurrence of skin cancer (p = 0.02), while those from California were significantly more knowledgeable about skin cancer risk factors such as sunbathing without sunscreen (p ? 0.001). Although students from Maryland were more concerned that exposure to the sun may give them skin cancer (p = 0.003) and more worried about the possibility of skin cancer (p < 0.001), they were less likely to engage in sun protection behaviors such as using sunscreen (p = 0.001). Conclusion: Based on this study, efforts to increase sun protective behaviors through education regarding skin cancer risk factors in Maryland are warranted

Scaling in Nonstationary Voltammetry Representations

Despite the widespread use of voltammetry for a range of chemical, biological, environmental, and industrial applications, there is still a lack of understanding regarding the functionality between the applied voltage and the resulting patterns in the current response. This is due to the highly nonlinear relation between the applied voltage and the nonstationary current response, which casts a direct association nonintuitive. In this Article, we focus on large-amplitude/high-frequency ac voltammetry, a technique that has shown to offer increased voltammetric detail compared to alternative methods, to study heterogeneous electrochemical reaction-diffusion cases using a nonstationary time-series analysis, the Hilbert transform, and symmetry considerations. We show that application of this signal processing technique minimizes the significant capacitance contribution associated with rapid voltammetric measurements. From a series of numerical simulations conducted for different voltage excitation parameters as well as kinetic, thermodynamic, and mass transport parameters, a number of scaling laws arise that are related to the underlying parameters/dynamics of the process. Under certain conditions, these observations allow the determination of all underlying parameters very rapidly, experiment duration typically ≤1 s, using standard electrode geometries and without any a priori assumptions regarding their value. The theoretical results derived from this analysis are compared to experiments with an outer-sphere electron-transfer species, Ru(NH_3)_6^(2+/3+), on different electrode materials, and the determined parameters are in excellent agreement with published values

Ideal material properties for capsules or vascular sustem used in cementitious self-healing materials

Self-healing in cementitious materials, i.e. concrete, has a huge potential towards reducing maintenance and repair costs and increasing the service life of concrete structures. The biggest advantage of self-healing concrete is that small cracks, who provide access to hazardous gasses and liquids, are healed and structural degradation is prevented. Several techniques are trending in the field of self-healing concrete, self-healing using bacteria, self-healing using a vascular system and self-healing using capsules. Focusing on the two latter, an encapsulation material is needed. This paper describes the ideal properties of such an encapsulation material, taking into account as many steps of the life-cycle of the self-healing concrete, i.e. from production until the end of the structure. Such an ideal encapsulation material should be resistant through time to the healing-agent as well as to the cementitious environment. The ideal material should be brittle enough to rupture upon cracking of the (aged) concrete on one hand, and on the other it should be strong enough to survive the concrete mixing and casting process. The properties are not always to be combined by one and the same material, combinations of materials who take up different requirements are possible. In current research glass is most often used as encapsulation material. It’s a brittle material which is able to contain the healing agent, but it also suffers from a slow chemical interaction with the alkali-environment, and a very low survival rate when implemented in realistic industrial concrete casting processes. The goal of this study is to investigate the wanted versus the needed properties in order to select other materials than glass or to select other materials to combine with glass