Existence of solutions to principal-agent problems with adverse selection under minimal assumptions

We prove an existence result for the principal-agent problem with adverse selection under general assumptions on preferences and allocation spaces. Instead of assuming that the allocation space is finite-dimensional or compact, we consider a more general coercivity condition which takes into account the principal's cost and the agents' preferences. Our existence proof is simple and flexible enough to adapt to partial participation models as well as to the case of type-dependent budget constraints.Comment: 22 page

Analysis of DNA DSB repair and production stability in CHO cells

Poster Number 13 ANALYSIS OF DNA DSB REPAIR AND PRODUCTION STABILITY IN CHO CELLS Xiaolin Zhang, Department of Chemical and Biomolecular Engineering, University of Delaware Delaware Biotechnology Institute, University of Delaware [email protected] Kelvin H. Lee, Department of Chemical and Biomolecular Engineering, University of Delaware Delaware Biotechnology Institute, University of Delaware Key Words: CHO cell, DSB repair, heterologous expression, production instability. Productivity of recombinant proteins in CHO cell lines often decreases over long-term cultivation. This production instability limits the use of CHO-based platforms and can negatively impact the capability of a manufacturing process to meet market demands. A method to prevent the production loss during long-term cultivation is highly desirable. Genome instability can reduce transgene copy number and is reported as a major cause for production instability. We hypothesize that the DNA double-strand break (DSB) repair system in CHO is deficient and associated with both genome and production instabilities. Our results indicated that CHO cells had a lower DSB repair rate compared to the bEnd.3 mouse endothelial cell line, which is consistent with our hypothesis. The ability to improve DSB repair in CHO may provide a strategy to prevent production instability. Therefore, we tested heterologous expression of eight DSB repair-related genes, and found that four genes could significantly improve DSB repair in CHO cells. To further assess the impact of improved DSB repair on protein production, each of the four heterologous genes was stably expressed in a secreted alkaline phosphatase (SEAP) producing cell line, and SEAP production in single clones was evaluated over three months in the absence of methotrexate (MTX). Our results showed that productivity correlated strongly with the SEAP copy number, and two heterologous genes could substantially improve the production retention during long-term cultivation

Choosing Wavelet Methods, Filters, and Lengths for Functional Brain Network Construction

Wavelet methods are widely used to decompose fMRI, EEG, or MEG signals into time series representing neurophysiological activity in fixed frequency bands. Using these time series, one can estimate frequency-band specific functional connectivity between sensors or regions of interest, and thereby construct functional brain networks that can be examined from a graph theoretic perspective. Despite their common use, however, practical guidelines for the choice of wavelet method, filter, and length have remained largely undelineated. Here, we explicitly explore the effects of wavelet method (MODWT vs. DWT), wavelet filter (Daubechies Extremal Phase, Daubechies Least Asymmetric, and Coiflet families), and wavelet length (2 to 24) - each essential parameters in wavelet-based methods - on the estimated values of network diagnostics and in their sensitivity to alterations in psychiatric disease. We observe that the MODWT method produces less variable estimates than the DWT method. We also observe that the length of the wavelet filter chosen has a greater impact on the estimated values of network diagnostics than the type of wavelet chosen. Furthermore, wavelet length impacts the sensitivity of the method to detect differences between health and disease and tunes classification accuracy. Collectively, our results suggest that the choice of wavelet method and length significantly alters the reliability and sensitivity of these methods in estimating values of network diagnostics drawn from graph theory. They furthermore demonstrate the importance of reporting the choices utilized in neuroimaging studies and support the utility of exploring wavelet parameters to maximize classification accuracy in the development of biomarkers of psychiatric disease and neurological disorders.Comment: working pape

On the initial-value problem in a rotating circular cylinder

Copyright © 2008 Cambridge University PressThe initial-value problem in rapidly rotating circular cylinders is revisited. Four different but related analyses are carried out: (i) we derive a modified asymptotic expression for the viscous decay factors valid for the inertial modes of a broad range of frequencies that are required for an asymptotic solution of the initial value problem at an arbitrarily small but fixed Ekman number; (ii) we perform a fully numerical analysis to estimate the viscous decay factors, showing satisfactory quantitative agreement between the modified asymptotic expression and the fuller numerics; (iii) we derive a modified time-dependent asymptotic solution of the initial value problem valid for an arbitrarily small but fixed Ekman number and (iv) we perform fully numerical simulations for the initial value problem at a small Ekman number, showing satisfactory quantitative agreement between the modified time-dependent solution and the numerical simulations

Me, Myself, and the Universe

When you look up in the night sky, you see stars.Hundreds, thousands of them, glimmering and glistening, each and every one bigger and brighter than our own sun.A hundred billion stars lie in our galaxy, and another hundred billion galaxies in our universe.Our minds are unable to comprehend how large the universe really is