407 research outputs found
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
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