Heat Capacity of Protein Folding

We construct a Hamiltonian for a single domain protein where the contact enthalpy and the chain entropy decrease linearly with the number of native contacts. The hydration effect upon protein unfolding is included by modeling water as ideal dipoles that are ordered around the unfolded surfaces, where the influence of these surfaces, covered with an ``ice-like'' shell of water, is represented by an effective field that directs the water dipoles. An intermolecular pair interaction between water molecules is also introduced. The heat capacity of the model exhibits the common feature of small globular proteins, two peaks corresponding to cold and warm unfolding, respectively. By introducing vibrational modes, we obtain quantitatively good accordance with experiments.Comment: 14 pages, LaTex, 4 figure

Placing the Czech shadow banking sector under the light

The size of the shadow banking sector (SBS) has more than doubled in the Czech Republic over the last decade. This places a potential burden on policy makers. On the one hand, the SBS complements regular banking by expanding access to credit and investments, enabling better risk sharing and maturity transformation, and supporting market liquidity. On the other hand, SBS activities can put the stability of the financial system at risk and amplify its procyclicality by exacerbating the buildup of leverage and asset price bubbles. We implement a FAVAR model of the Czech economy to determine the impact of macroeconomic factors on the SBS. We find that the SBS: (i) is sensitive to changes in market interest rates and term spread; (ii) exhibits great procyclicality; (iii) can act as a complement to regular banking and satisfy some additional demand for credit. We also define some potential risks of continued growth of the SBS, linked to our empirical evidence.Web of Science29128

Four-states phase diagram of proteins

A four states phase diagram for protein folding as a function of temperature and solvent quality is derived from an improved 2-d lattice model taking into account the temperature dependence of the hydrophobic effect. The phase diagram exhibits native, globule and two coil-type regions. In agreement with experiment, the model reproduces the phase transitions indicative of both warm and cold denaturations. Finally, it predicts transitions between the two coil states and a critical point.Comment: 7 pages, 5 figures. Accepted for publication in Europhysics Letter

Hamiltonian model for multidimensional epistasis

We propose and solve a Hamiltonian model for multidimensional epistastatic interactions between beneficial mutations. The model is able to give rise either to a phase transition between two equilibrium states, without any coexistence, or exhibits a state where hybrid species can coexist, with gradual passage from one wild type to another. The transition takes place as a function of the "tolerance" of the environment, which we define as the amount of noise in the system.Comment: 3 pages, 2 figures (in seperate files) spelling corrected and a reference adde

Two-step estimation of latent trait models

We consider two-step estimation of latent variable models, in which just the measurement model is estimated in the first step and the measurement parameters are then fixed at their estimated values in the second step where the structural model is estimated. We show how this approach can be implemented for latent trait models (item response theory models) where the latent variables are continuous and their measurement indicators are categorical variables. The properties of two-step estimators are examined using simulation studies and applied examples. They perform well, and have attractive practical and conceptual properties compared to the alternative one-step and three-step approaches. These results are in line with previous findings for other families of latent variable models. This provides strong evidence that two-step estimation is a flexible and useful general method of estimation for different types of latent variable models.Comment: 39 pages, 2 figures, 17 table

A Social Justice Perspective on Medicare Part D in an Age of Reform: Critical Implications of Trends in Health Care Policy and Advocacy

This article examines the Medicare Prescription Drug, Improvement, and Modernization Act of 2003 (MMA) in its current form and explains why a critical perspective is useful when analyzing the policy and reform efforts. Using this approach, we consider the development of the policy and describe ways that gender and racial differences may hinder equal access to medications for some of the most vulnerable older adults. This article explores the implications of gender and racial disparities under the MMA and ramifications of health care reform efforts that could potentially impede, rather than promote, a social justice agenda. Beyond the political advantage of the MMA\u27s current structure, reconsideration should include the potentialfor disproportionate negative economic and health effects for women and people in historically disadvantaged minority groups