Differential Conductance and Quantum Interference in Kondo Systems

We present a large-N theory for the differential conductance, dI/dV, in Kondo systems measured via scanning tunneling spectroscopy. We demonstrate that quantum interference between tunneling processes into the conduction band and into the magnetic f-electron states is crucial in determining the experimental Fano lineshape of dI/dV. This allows one to uniquely extract the Kondo coupling and the ratio of the tunneling amplitudes from the experimental dI/dV curve. Finally, we show that dI/dV directly reflects the strength of the antiferromagnetic interaction in Kondo lattice systems.Comment: 4 pages, 4 figure

Adaptive system and method for signal generation Patent

Adaptive signal generating system and logic circuits for satellite television system

Association Studies of 22 Candidate SNPs wtih Late-Onset Alzheimer's Disease

Alzheimer's disease (AD) is a complex and multifactorial disease with the possible involvement of several genes. Complex diseases such as AD have a large affect on the public health. It was estimated in 2007 that over 5 million Americans had AD, and more than $91 billion dollars was spent by medicare on AD and other dementias. Genetics plays a significant role in the etiology of the disease, therefore, it is of public health importance that the genetics of AD be investigated. With the exception of the APOE gene as a susceptibility marker no other genes have been identified for late-onset AD (LOAD). A recent genome wide association study of 17,343 gene-based putative functional single nucleotide polymorphisms (SNPs) found 19 significant variants, including 3 linked to APOE, showing association with LOAD in several population samples. We have set out to replicate the 16 new significant associations in a large case-control cohort of American Whites. Additionally we examined six variants present in positional and/or biological candidate genes for AD. We genotyped the 22 SNPs in up to 1,009 Caucasian Americans with LOAD and up to 1,010 age matched older healthy Caucasian Americans. All variants were genotyped using 5' nuclease assays. We did not observe a statistically significant association between the SNPs with the risk of AD, either individually or stratified by APOE. Our data suggest that the association of the studied variants with LOAD, if it exists, is not statistically significant in our population study

Defects in Heavy-Fermion Materials: Unveiling Strong Correlations in Real Space

Complexity in materials often arises from competing interactions at the atomic length scale. One such example are the strongly correlated heavy-fermion materials where the competition between Kondo screening and antiferromagnetic ordering is believed to be the origin of their puzzling non-Fermi-liquid properties. Insight into such complex physical behavior in strongly correlated electron systems can be gained by impurity doping. Here, we develop a microscopic theoretical framework to demonstrate that defects implanted in heavy-fermion materials provide an opportunity for unveiling competing interactions and their correlations in real space. Defect-induced perturbations in the electronic and magnetic correlations possess characteristically different spatial patterns that can be visualized via their spectroscopic signatures in the local density of states or non-local spin susceptibility. These real space patterns provide insight into the complex electronic structure of heavy-fermion materials, the light or heavy character of the perturbed states, and the hybridization between them. The strongly correlated nature of these materials also manifests itself in highly non-linear quantum interference effects between defects that can drive the system through a first-order phase transition to a novel inhomogeneous ground state.Comment: 11 pages, 7 figure

Disorder and quasiparticle interference in heavy-fermion materials

Using a large-N approach, we study the effect of disorder in the Kondo-screened phase of heavy-fermion materials. We demonstrate that the strong feedback between the hybridization and the conduction electron charge density magnifies the effect of disorder, such that already small concentrations of defects strongly disorder the materials' local electronic structure, while only weakly affecting their spatially averaged, thermodynamic properties. Finally, we show that the microscopic nature of defects can be identified through their characteristic signatures in the hybridization and quasiparticle interference spectrum.Comment: 5 pages; v2: published versio

Political Party Affiliation, Regional Variation and the Demographic Correlates of Euroscepticism on the Isle of Great Britain

Euroscepticism or opposition to the European Union has become a growing political philosophy among broad segments of Europe’s populace. This philosophy has manifested itself in some form throughout most of the European Union, but opinion polls and voter data indicate Euroscepticism is most acute within the United Kingdom and both among its general citizenry and elected officials. In the 2009 EU Parliament elections for the United Kingdom, the right wing United Kingdom Independence Party gained its most ever seats in the Parliament while the far-right British National Party gained its first ever seats in a national election. With overtly Eurosceptic political parties gaining unprecedented support, the UK is poised to enter a new chapter of Euroscepticism. This thesis examined the spatial variation of Euroscepticism in the three constituent nations of the Isle of Great Britain (England, Scotland and Wales). In this analysis, several key socio-economic variables such as lack of education, unemployment rates and low population density were found to strongly correlate with Eurosceptic voting behavior whereas geographically the region identified as the most Eurosceptic was the West Midlands and the least Eurosceptic was Scotland. This work focused mainly on the 2009 EU Parliament election at both regional and local scales in England, Scotland and Wales, as well as local council elections in England from 2007 to 2010

Hidden Order Transition in URu2Si2 and the Emergence of a Coherent Kondo Lattice

Using a large-N approach, we demonstrate that the differential conductance and quasi-particle interference pattern measured in recent scanning tunneling spectroscopy experiments (A.R. Schmidt et al. Nature 465, 570 (2010); P. Aynajian et al., PNAS 107, 10383 (2010)) in URu2Si2 are consistent with the emergence of a coherent Kondo lattice below its hidden order transition (HOT). Its formation is driven by a significant increase in the quasi-particle lifetime, which could arise from the emergence of a yet unknown order parameter at the HOT.Comment: 5 pages, 3 figure

How Data Mining can be used to predict SIDS In ECG signal data

https://scholarworks.moreheadstate.edu/student_scholarship_posters/1108/thumbnail.jp