Homebuying in New Orleans Before and After Katrina: Patterns by Space, Race and Income

Natural disasters can conceivably have significant impacts on the “neighborhood sorting” of different racial or economic groups across intrametropolitan space. Using Home Mortgage Disclosure Act data we examine mortgage-financed homebuying activity within the New Orleans MSA before and after Hurricane Katrina. We find that, while the total amount of homebuying in the 7-parish New Orleans MSA was relatively unchanged between 2004 and 2006, homebuying in the city declined significantly, and declined most in places experiencing severe storm damage. We also find that after Hurricane Katrina, the proportion of homebuyers in the region and the city who were African-American or low-income declined. Finally, we find that segregation levels of African-American and lower-income homebuyers f declined in the year following Katrina. However, some of this effect is likely due to smaller overall numbers of lower-income and African-American buyers in the region.New Orleans, housing after disasters, segregation

Doctor of Philosophy

dissertationElectrically and Optically detected magnetic resonance (EDMR and ODMR) spectroscopy allows investigation of the microscopic nature of paramagnetic centers which influence the electrical or optoelectronic properties of semiconductors. Traditionally, EDMR and ODMR have been conducted as adiabatic magnetic field sweep spectroscopies under continuous wave (cw) application of electromagnetic fields. It is shown here that information about the dynamics of spin-dependent processes obtained from cwEDMR and cwODMR is determined by many electronic- and spin-relaxation parameters, which make the interpretation of experimental data quantitatively ambiguous. In contrast, it is shown that transient EDMR and ODMR experiments, so called pulsed (p)EDMR and pODMR, are significantly less ambiguous. For spin-dependent processes based on intermediate pairs of paramagnetic states, the cwEDMR and cwODMR as well as pEDMR and pODMR dynamics are derived analytically and the application of these results for the interpretation of experimental data is discussed for two examples: (i) The pEDMR study of spin-dependent recombination in silicon rich hydrogenated amorphous silicon nitride (a-SiNx:H) which showed the presence of a variety of mechanisms such as dangling bond recombination through weakly spin-coupled paramagnetic states but also recombination through band tail states which were strongly dipolar or exchange coupled. These processes had previously been observed in hydrogenated amorphous silicon (a-Si:H). However, while in a-Si:H, these processes took place solely as geminate recombination, they were of nongeminate nature in the a-SiNx:H. (ii) The pODMR study of excitonic recombination in a ?-conjugated polymer, namely, poly[2-methoxy-5-(20- ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV). The presence of magnetic resonance induced spin-beat oscillations in the fluorescence intensity was confirmed. Based on the existing polaron-pair recombination model, previously pEDMR-detected beat signals seen here with pODMR in an identical manner. Two types of MEH-PPV, one fully hydrogenated and one partially deuterated were subjected to pODMR. The deuterated materials showed a different beat oscillation dependence of the driving field power pattern which was indicative of smaller hyperfine fields in the deuterated material

Integration of multiple environmental stresses for compound gene regulation in Arabidopsis thaliana

Plants are known to respond to various types of environmental stresses arising from physicochemical changes and other organisms. As plants often simultaneously experience multiple stress factors due to their immobility, capacity to appropriately regulate gene expression by integrating multiple stress signals is crucial for successful adaptation to hostile environments. Although significant progress has been made in elucidating the molecular mechanisms for regulation of stress response genes under single stress, little is known about the effects of combined stress signals on gene regulation and their associated mechanisms. This thesis aimed to contribute to the understanding of plant stress response by studying the signal integration mechanisms under various perspectives: first, the thesis explored how multiple stress signals affect the choices over discretised regulatory outcomes, such as up-regulation or down-regulation. We propose that processing of multiple signals can be described as logical operations, and subsequently investigate the mechanisms for each signal integration outcome by constructing logical model of intracellular signalling network. The resulting insight was applied to analyse a transcriptomic dataset from the model plant Arabidopsis thaliana, leading to novel hypotheses about potential crosstalk interactions that are missing between multiple stress signalling pathways. In parallel, the thesis also explored the cases where integration of multiple stress signals modulates dynamics of gene expression. An experimental study of the expression profile of Response-to-Dehydration 29A (RD29A), a model stress response gene, was conducted to show that combination of multiple stress inputs introduces a unique qualitative effect on dynamics of gene expression. The origin of this behaviour was investigated via a dynamical model of the RD29A regulatory network, which subsequently revealed potential interactions in the regulatory network that are currently unknown. Taken together, this thesis argues that systematic comparison between gene regulatory outcomes under single and combined stress inputs provides a crucial source of information for discovering functionally significant regulatory interactions in the stress signalling network.Open Acces

Bookmark search: A web-based bookmark search engine

The objective of the project is to create a search engine in which the databases of links are the bookmarks uploaded by the user. The main idea of the BOOKMARK-SEARCH system is the sharing of bookmarks resources required carrying on an Internet search. It aims to provide an affordable search solution to users while sharing bookmarks resouces

Modulation frequency dependence of continuous-wave optically/electrically detected magnetic resonance

pre-printContinuous-wave optically and electrically detected magnetic resonance spectroscopy (cwODMR/cwEDMR) allow the investigation of paramagnetic states involved in spin-dependent transitions, like recombination and transport. Although experimentally similar to conventional electron spin resonance (ESR), there exist limitations when applying models originally developed for ESR to observables (luminescence and electric current) of cwODMR and cwEDMR. Here we present closed-form solutions for the modulation frequency dependence of cwODMR and cwEDMR based on an intermediate pair recombination model and discuss ambiguities which arise when attempting to distinguish the dominant spin-dependent processes underlying experimental data. These include (1) a large number of quantitatively different models cannot be differentiated; (2) signs of signals are determined not only by recombination but also by other processes like dissociation, intersystem-crossing, pair generation, and even experimental parameters, such as modulation frequency, microwave power, and temperature; (3) radiative and nonradiative recombination cannot be distinguished due to the observed signs of cwODMR and cwEDMR experiments

Particle-in-cell and weak turbulence simulations of plasma emission

The plasma emission process, which is the mechanism for solar type II and type III radio bursts phenomena, is studied by means of particle-in-cell and weak turbulence simulation methods. By plasma emission, it is meant as a loose description of a series of processes, starting from the solar flare associated electron beam exciting Langmuir and ion-acoustic turbulence, and subsequent partial conversion of beam energy into the radiation energy by nonlinear processes. Particle-in-cell (PIC) simulation is rigorous but the method is computationally intense, and it is difficult to diagnose the results. Numerical solution of equations of weak turbulence (WT) theory, termed WT simulation, on the other hand, is efficient and naturally lends itself to diagnostics since various terms in the equation can be turned on or off. Nevertheless, WT theory is based upon a number of assumptions. It is, therefore, desirable to compare the two methods, which is carried out for the first time in the present paper with numerical solutions of the complete set of equations of the WT theory and with two-dimensional electromagnetic PIC simulation. Upon making quantitative comparisons it is found that WT theory is largely valid, although some discrepancies are also found. The present study also indicates that it requires large computational resources in order to accurately simulate the radiation emission processes, especially for low electron beam speeds. Findings from the present paper thus imply that both methods may be useful for the study of solar radio emissions as they are complementary.Comment: 21 pages, 9 figure