Semiclassical quantization of multidimensional systems

Low order classical perturbation theory is used to obtain semiclassical eigenvalues for a system of three anharmonically coupled oscillators. The results in the low energy region studied here agree well with the "exact" quantum values. The latter had been calculated by matrix diagonalization using a large basis set

Depletion of chondrocyte primary cilia reduces the compressive modulus of articular cartilage

Primary cilia are slender, microtubule based structures found in the majority of cell types with one cilium per cell. In articular cartilage, primary cilia are required for chondrocyte mechanotransduction and the development of healthy tissue. Loss of primary cilia in Col2aCre;ift88(fl/fl) transgenic mice results in up-regulation of osteoarthritic (OA) markers and development of OA like cartilage with greater thickness and reduced mechanical stiffness. However no previous studies have examined whether loss of primary cilia influences the intrinsic mechanical properties of articular cartilage matrix in the form of the modulus or just the structural properties of the tissue. The present study describes a modified analytical model to derive the viscoelastic moduli based on previous experimental indentation data. Results show that the increased thickness of the articular cartilage in the Col2aCre;ift88(fl/fl) transgenic mice is associated with a reduction in both the instantaneous and equilibrium moduli at indentation strains of greater than 20%. This reveals that the loss of primary cilia causes a significant reduction in the mechanical properties of cartilage particularly in the deeper zones and possibly the underlying bone. This is consistent with histological analysis and confirms the importance of primary cilia in the development of a mechanically functional articular cartilage

A Decade After Lehman: Taking Stock of Quantitative Easing and Regulation

The Lehman failure precipitated the Great Recession and forced economic policy into unchartered terrain. This paper provides a retrospective on the policy response and links to the underwhelming economic recovery. The exposition is kept non-technical to facilitate wider access. Contrary to perceptions that banks remain vulnerable, this paper argues that regulation strengthened U.S. banks across a variety of dimensions. The deleveraging involved in the transition to stronger banks tightened financial conditions and offset the significant monetary stimulus. The failure to fully capture these offsetting policy forces explains the systematic forecasting errors—both markets and the Fed have consistently overestimated the strength of the economic cycle. Quantitative Easing resulted in a ballooning of excess reserves in the banking system, but payment of interest on excess reserves helped bank recapitalisation. The combination of stronger banks and excess reserves has the potential, unlike in previous cycles, to drive a late cycle surge in growth

The Economic Feasibility of Producing Ethanol from Corn Stover and Hardwood in Minnesota

Resource /Energy Economics and Policy,

Bars to Education: The Use of Criminal History Information in College Admissions

One in four Americans has a record reflecting some form of involvement with the criminal justice system, and the law currently does very little to protect an individual from discriminatory treatment on the basis of that record. In 2010, the Center for Community Alternatives published a report that revealed a widespread practice among colleges and universities of obtaining and relying upon criminal history information in admissions proceedings. This Note asks whether, if this practice results in a racially disproportionate adverse impact on admissions decisions, there exists disparate impact liability that could be challenged by the Department of Education under Title VI of the Civil Rights Act. The Note begins by focusing on the well-documented overrepresentation of people of color in the criminal justice system and some of the post-incarceration social harms that affect this population. Next, the Note explores challenges to the use of criminal history information in the employment context—which has received much more attention than higher education—and how disparate impact frameworks in education cases have been used to challenge other practices that create disproportionate adverse effects. Finally, the Note describes the application of the disparate impact test to the practice at issue and concludes that if a prima facie case can be made, the purported educational necessity behind this practice can be achieved through less discriminatory means

Global parameter identification of stochastic reaction networks from single trajectories

We consider the problem of inferring the unknown parameters of a stochastic biochemical network model from a single measured time-course of the concentration of some of the involved species. Such measurements are available, e.g., from live-cell fluorescence microscopy in image-based systems biology. In addition, fluctuation time-courses from, e.g., fluorescence correlation spectroscopy provide additional information about the system dynamics that can be used to more robustly infer parameters than when considering only mean concentrations. Estimating model parameters from a single experimental trajectory enables single-cell measurements and quantification of cell--cell variability. We propose a novel combination of an adaptive Monte Carlo sampler, called Gaussian Adaptation, and efficient exact stochastic simulation algorithms that allows parameter identification from single stochastic trajectories. We benchmark the proposed method on a linear and a non-linear reaction network at steady state and during transient phases. In addition, we demonstrate that the present method also provides an ellipsoidal volume estimate of the viable part of parameter space and is able to estimate the physical volume of the compartment in which the observed reactions take place.Comment: Article in print as a book chapter in Springer's "Advances in Systems Biology