On the origin of duality in the quantum Hall system

We discuss the possible origin of the duality observed in the quantum Hall current-voltage characteristics. We clarify the difference between "particle-vortex" (complex modular) duality, which acts on the full transport tensor, and "charge-flux" ("real") duality, which acts directly on the filling factor. Comparison with experiment strongly favors the form of duality which descends from the modular symmetry group acting holomorphically on the compexified conductivity.Comment: 5 pages, 3 figure

Life-history strategies of primates

This thesis examines variation in the life-history parameters of primates using comparative techniques. Several theories of life-history evolution are introduced in the first chapter, together with a summary of the previous work on this topic. Scaling methods are used to separate variation in life-history parameters that is correlated with body weight from that which cannot be predicted from an animal's size. These methods are described in detail in Chapter 2. Chapter 3 describes the variation found in body size and basal metabolic rate and correlations with phylogeny, diet, habitat and other aspects of ecology. Patterns of variation in reproductive parameters, particularly reproductive rates (as measured by the intrinsic rate of natural increase, r_{max}) and reproductive effort (as measured by prenatal and postnatal infant growth rates), are described and compared with patterns reported in other studies. Possible reasons for the scaling relationships found are suggested and the influences of metabolic rate, phylogeny, diet, habitat and other aspects of ecology are investigated. This is carried out for all primates in Chapters 4-6 and in Chapter 7 there is a closer look at the cercopithecine monkeys. It is suggested that r_{max} is influenced by the predictability of the environment, with more unpredictable environments being associated with a higher r_{max} that more predictable environments. However, this is only found when body weight effects are removed from the r_{max} data. Growth rates do not appear to be correlated with environmental predictability but are mainly correlated with body size and relative metabolic rate. There is some indication that the degree of parental care may also be correlated with relative growth rates. It is concluded that no single theory of life-history evolution can amount for the variation found in primate life-histories, but that some aspects of several theories may be useful in describing the patterns found

THE INFLUENCE OF FOAM DISCONTINUITY IN THE SHEAR ZONE OF STRUCTURAL INSULATED PANEL BEAMS

The effect of foam discontinuity in the shear zone of structural insulated panel (SIP) beams was investigated in the current research. Two depths of 15.24 cm and 31.11 cm (6.5 in and 12.25 in) (SIPs) were evaluated in 1/3-point bending. Panels were sawn into beams, each approximately 29.84 cm (11.75 in.) wide, for mechanical testing. Half of the panels had joints or discontinuities in the foam layer in a location that was subject to shear stress during the bending tests. Half of the panels had joints or discontinuities in the foam layer in a location that was subject to shear stress during the bending tests. Half of the panels did not have joints or discontinuities in the foam layer in the locations that were subject to shear stress during the bending tests. The specimens with no foam discontinuity, stressed in shear, were approximately twice as strong as the specimens with a foam discontinuity. This finding has implications for routine testing and evaluation as well as for allowable properties. In the case of routine testing, foam discontinuities should purposefully be located in the zone of maximum shear as these appear to be a limiting factor. In cases where a producer manufactures SIPs with zero discontinuities, it may be prudent to seek premium value as those panels would achieve superior properties. Keywords: Structural insulated panels (SIPs), shear stress, bending test, foam, joints and routine testing.

Lentiviral-mediated delivery of mutant huntingtin in the striatum of rats induces a selective neuropathology modulated by polyglutamine repeat size, huntingtin expression levels, and protein length.

A new strategy based on lentiviral-mediated delivery of mutant huntingtin (htt) was used to create a genetic model of Huntington's disease (HD) in rats and to assess the relative contribution of polyglutamine (CAG) repeat size, htt expression levels, and protein length on the onset and specificity of the pathology. Lentiviral vectors coding for the first 171, 853, and 1520 amino acids of wild-type (19 CAG) or mutant htt (44, 66, and 82 CAG) driven by either the phosphoglycerate kinase 1 (PGK) or the cytomegalovirus (CMV) promoters were injected in rat striatum. A progressive pathology characterized by sequential appearance of ubiquitinated htt aggregates, loss of dopamine- and cAMP-regulated phosphoprotein of 32 kDa staining, and cell death was observed over 6 months with mutant htt. Earlier onset and more severe pathology occurred with shorter fragments, longer CAG repeats, and higher expression levels. Interestingly, the aggregates were predominantly located in the nucleus of PGK-htt171-injected rats, whereas they were present in both the nucleus and processes of CMV-htt171-injected animals expressing lower transgene levels. Finally, a selective sparing of interneurons was observed in animals injected with vectors expressing mutant htt. These data demonstrate that lentiviral-mediated expression of mutant htt provides a robust in vivo genetic model for selective neural degeneration that will facilitate future studies on the pathogenesis of cell death and experimental therapeutics for HD

Geology of the Illinois parts of the Cairo, La Center, and Thebes quadrangles

Ope

Pattern Registration Between Spherical Block-Copolymer Domains and Topographical Templates

Pattern registration is achieved in thin films of self-assembling block copolymers by using a topographical template to guide the positions of the polymer domains. The placement accuracy of the polymer domains is related to the edge roughness of the topographical template, and the ultimate placement accuracy is assessed (see Figure). For a block copolymer with spherical morphology, a registered polymer array is achieved by using a two-dimensional template

Domain wall mobility in nanowires: transverse versus vortex walls

The motion of domain walls in ferromagnetic, cylindrical nanowires is investigated numerically by solving the Landau-Lifshitz-Gilbert equation for a classical spin model in which energy contributions from exchange, crystalline anisotropy, dipole-dipole interaction, and a driving magnetic field are considered. Depending on the diameter, either transverse domain walls or vortex walls are found. The transverse domain wall is observed for diameters smaller than the exchange length of the given material. Here, the system behaves effectively one-dimensional and the domain wall mobility agrees with a result derived for a one-dimensional wall by Slonczewski. For low damping the domain wall mobility decreases with decreasing damping constant. With increasing diameter, a crossover to a vortex wall sets in which enhances the domain wall mobility drastically. For a vortex wall the domain wall mobility is described by the Walker-formula, with a domain wall width depending on the diameter of the wire. The main difference is the dependence on damping: for a vortex wall the domain wall mobility can be drastically increased for small values of the damping constant up to a factor of $1/\alpha^2$.Comment: 5 pages, 6 figure

Transverse magnetization in Cu/Ni/Cu epitaxial nanorings

The micromagnetic structure in epitaxial (001)-oriented Cu/Ni(14 nm)/Cu rings fabricated by electron beam and focused ion beam lithographies with external diameter of 3 µm and linewidths between 100 and 500 nm is presented. We found that a state with radial orientation of the magnetization prevails at remanence. The evaluation of the magnetoelastic, magnetocrystalline and magnetostatic energies shows that a value as low as 1.5 × 10-3 for the anisotropic relaxation of the in-plane strain components is enough to induce an effective radial easy magnetization direction

Effects of adhesion on the measurement of thin film mechanical properties by nanoindentation

Experiments have been performed on soft aluminum films deposited on hard ceramic substrates to explore the influences of interfacial adhesion on mechanical property measurement by nanoindentation. The substrate materials included soda-lime silicate glass, aluminum oxynitride (ALON), and (100) sapphire. Thin films of high purity aluminum were sputtered onto each substrate to a thickness of 500 nm. Because the films were deposited simultaneously, the only major difference in the specimens was the nature of the substrate, which exerts an important influence on film adhesion through interfacial chemistry. Of the substrates examined, aluminum adheres strongly to glass and sapphire, but poorly to ALON. In addition, two different types of aluminum films on sapphire were examined - one with and the other without a 10 nm interlayer of amorphous carbon which significantly reduces film adhesion. Testing revealed important differences in the hardness of the specimens when measured by standard nanoindentation methods. Characterization of the residual hardness impressions by high resolution scanning electron microscopy showed that the hardness differences arise from an influence of interfacial debonding and film delamination on pile-up in the film. Furthermore, when the pile-up is accounted for in contact area determinations, the film hardness is actually independent of the substrate, thus indicating that the hardness differences observed in nanoindentation testing are an artifact of the testing analysis procedure. Results of the experiments are documented and discussed. 8 refs., 6 figs., 1 tab

Nanoindentation hardness of soft films on hard substrates: Effects of the substrate

The ability to accurately measure the mechanical properties of thin metallic films is important in the semiconductor industry as it relates to device reliability issues. One popular technique for measuring thin film mechanical properties is nanoindentation. This technique has the advantage of being able to measure properties such as hardness and elastic modulus without removing a film from its substrate. However, according to a widely-held rule of thumb, intrinsic film properties can be measured in a manner which is not influenced by the substrate only if the indentation depth is kept to less than 10% of the film thickness, which is often not practical. In this work, a method for making substrate independent hardness measurements of soft metallic films on hard substrates is proposed. The primary issue to be addressed is the substrate-induced enhancement of indentation pile-up and the ways in which this pile-up influences the contact area determined from analyses of nanoindentation load- displacement data. Based on experimental observations of soft aluminum films on silicon, glass, and sapphire substrates, a simple empirical relationship is derived which relates the amount of pile-up to the contact depth. From this relationship, a simple method is developed which allows the intrinsic hardness of the film to be measured by nanoindentation methods even when the indenter penetrates through the film into the substrate