Boolean Models of Bistable Biological Systems

This paper presents an algorithm for approximating certain types of dynamical systems given by a system of ordinary delay differential equations by a Boolean network model. Often Boolean models are much simpler to understand than complex differential equations models. The motivation for this work comes from mathematical systems biology. While Boolean mechanisms do not provide information about exact concentration rates or time scales, they are often sufficient to capture steady states and other key dynamics. Due to their intuitive nature, such models are very appealing to researchers in the life sciences. This paper is focused on dynamical systems that exhibit bistability and are desc ribedby delay equations. It is shown that if a certain motif including a feedback loop is present in the wiring diagram of the system, the Boolean model captures the bistability of molecular switches. The method is appl ied to two examples from biology, the lac operon and the phage lambda lysis/lysogeny switch

Quantum creation of an Inhomogeneous universe

In this paper we study a class of inhomogeneous cosmological models which is a modified version of what is usually called the Lema\^itre-Tolman model. We assume that we have a space with 2-dimensional locally homogeneous spacelike surfaces. In addition we assume they are compact. Classically we investigate both homogeneous and inhomogeneous spacetimes which this model describe. For instance one is a quotient of the AdS$_4$ space which resembles the BTZ black hole in AdS$_3$. Due to the complexity of the model we indicate a simpler model which can be quantized easily. This model still has the feature that it is in general inhomogeneous. How this model could describe a spontaneous creation of a universe through a tunneling event is emphasized.Comment: 21 pages, 5 ps figures, REVTeX, new subsection include

Starobinsky Model in Schroedinger Description

In the Starobinsky inflationary model inflation is driven by quantum corrections to the vacuum Einstein equation. We reduce the Wheeler-DeWitt equation corresponding to the Starobinsky model to a Schroedinger form containing time. The Schroedinger equation is solved with a Gaussian ansatz. Using the prescription for the normalization constant of the wavefunction given in our previous work, we show that the Gaussian ansatz demands Hawking type initial conditions for the wavefunction of the universe. The wormholes induce randomness in initial states suggesting a basis for time-contained description of the Wheeler-DeWitt equation.Comment: 19 Pages, LaTeX, no figure, gross typographical mistake

Arrow of time in a recollapsing quantum universe

We show that the Wheeler-DeWitt equation with a consistent boundary condition is only compatible with an arrow of time that formally reverses in a recollapsing universe. Consistency of these opposite arrows is facilitated by quantum effects in the region of the classical turning point. Since gravitational time dilation diverges at horizons, collapsing matter must then start re-expanding ``anticausally" (controlled by the reversed arrow) before horizons or singularities can form. We also discuss the meaning of the time-asymmetric expression used in the definition of ``consistent histories". We finally emphasize that there is no mass inflation nor any information loss paradox in this scenario.Comment: Many conceptual clarifications include

Systematic review and individual patient data meta-analysis of sex differences in depression and prognosis in persons with myocardial infarction: a MINDMAPS study

Objective - Using combined individual patient data (IPD) from prospective studies, we explored sex differences in depression and prognosis post-myocardial infarction (MI), and determined whether disease indices could account for found differences. Methods - Meta-analysis of IPD from 10,175 MI patients who completed diagnostic interviews or depression questionnaires from 16 prospective studies of MI patients, identified by systematic review for the MINDMAPS study. Multilevel logistic and Cox regression models were used to determine sex differences in prevalence of depression and sex-specific effects of depression on subsequent cardiovascular morbidity and all-cause mortality. Results - Combined interview and questionnaire data from observational studies showed that 36% (635/1760) of women and 29% (1575/5526) of men reported elevated levels of depression (age-adjusted OR=0.68, 95% CI 0.60 to 0.77, p (sex*depression interaction p Conclusions - The prevalence of depression post-MI was higher in women than men, but the association between depression and cardiac prognosis was worse for men. LVEF was associated with depression in men only, and accounted for the increased risk of all-cause mortality in depressed men versus women, suggesting that depression in men post-MI may in part reflect cardiovascular disease severity

Period-doubling bifurcation in strongly anisotropic Bianchi I quantum cosmology

We solve the Wheeler-DeWitt equation for the minisuperspace of a cosmological model of Bianchi type I with a minimally coupled massive scalar field $\phi$ as source by generalizing the calculation of Lukash and Schmidt [1]. Contrarily to other approaches we allow strong anisotropy. Combining analytical and numerical methods, we apply an adiabatic approximation for $\phi$, and as new feature we find a period-doubling bifurcation. This bifurcation takes place near the cosmological quantum boundary, i.e., the boundary of the quasiclassical region with oscillating $\psi$-function where the WKB-approximation is good. The numerical calculations suggest that such a notion of a ``cosmological quantum boundary'' is well-defined, because sharply beyond that boundary, the WKB-approximation is no more applicable at all. This result confirms the adequateness of the introduction of a cosmological quantum boundary in quantum cosmology.Comment: Latest update of the paper at http://www.physik.fu-berlin.de/~mbach/publics.html#

Adjusted prognostic association of post-myocardial infarction depression withmortality and cardiovascular events: an individual patient data meta-analysis

Background: The association between depression after myocardial infarction (post-MI) and increased risk of mortality and cardiac morbidity may be due to cardiac disease severity. Aims: To combine original data from studies on the association between post-MI depression and prognosis into one database. To investigate to what extent post-MI depression predicts prognosis independently of disease severity. Method: Individual patient data meta-analysis of studies, using multilevel, multivariable Cox regression analyses. Results:Sixteen studies participated, creating a database of 10,175 post-MI patients. HRs for post-MI depression were 1.32 (95%CI 1.26-1.38, p Conclusions: The association between post-MI depression and prognosis is attenuated after adjustment for cardiac disease severity. Still, depression remains independently associated with prognosis, with a 22% increased risk of all-cause mortality and a 13% increased risk of cardiovascular events per standard deviation in depression z-score. Declaration of interest: None

Metal-macrofauna interactions determine microbial community structure and function in copper contaminated sediments

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