The Effect of Temperature on Enzyme Activity and on the Affinity of Enzymes to their Substrates

Peer Reviewe

Note on Phase Space Contraction and Entropy Production in Thermostatted Hamiltonian Systems

The phase space contraction and the entropy production rates of Hamiltonian systems in an external field, thermostatted to obtain a stationary state are considered. While for stationary states with a constant kinetic energy the two rates are formally equal for all numbers of particles N, for stationary states with constant total (kinetic and potential) energy this only obtains for large N. However, in both cases a large number of particles is required to obtain equality with the entropy production rate of Irreversible Thermodynamics. Consequences of this for the positivity of the transport coefficients and for the Onsager relations are discussed. Numerical results are presented for the special case of the Lorentz gas.Comment: 16 pages including 1 table and 3 figures. LaTeX forma

Onsagerian Quantum Mechanics

We describe the basic quantum-mechanical categories and properties of the thermodynamical basis of Onsagers theorem. 3 basic principles are used: 1. energy dissipation; 2. Hamiltonian formalism; 3. Onsagers linearity. We obtain the 2 characteristic values of the observables, their main-value and the deviation, the first and second momentums of the probability distribution function, which we also derived also from the same principles

The EISCAT meteor code

The EISCAT UHF system has the unique capability to determine meteor vector velocities from the head echo Doppler shifts measured at the three sites. Since even meteors spending a very short time in the common volume produce analysable events, the technique lends itself ideally to mapping the orbits of meteors arriving from arbitrary directions over most of the upper hemisphere. <br><br> A radar mode optimised for this application was developed in 2001/2002. A specially selected low-sidelobe 32-bit pseudo-random binary sequence is used to binary phase shift key (BPSK) the transmitted carrier. The baud-length is 2.4 μs and the receiver bandwidth is 1.6 MHz to accommodate both the resulting modulation bandwidth and the target Doppler shift. Sampling is at 0.6 μs, corresponding to 90-m range resolution. Target range and Doppler velocity are extracted from the raw data in a multi-step matched-filter procedure. For strong (SNR>5) events the Doppler velocity standard deviation is 100–150 m/s. The effective range resolution is about 30 m, allowing very accurate time-of-flight velocity estimates. On average, Doppler and time-of-flight (TOF) velocities agree to within about one part in 10<sup>3</sup>. Two or more targets simultaneously present in the beam can be resolved down to a range separation <300 m as long as their Doppler shifts differ by more than a few km/s

On the halide hydration study: Development of first-principles halide ion-water interaction potential based on a polarizable model

The development of first-principles halide-water interaction potentials for fluoride and iodide anions is presented. The model adopted is the mobile charge densities in harmonic oscillator that allows for a flexible and polarizable character of the interacting particles. The set of points of the quantum mechanical potential energy surfaces are calculated up to the MP2 level. The nonadditive many-body contributions were included explicitly at the three-body terms. Structural and energetic properties of the [ X(H2O)n ]- clusters (n=1 – 6) are studied with the new interaction potentials developed. Halide aqueous solutions are also studied by means of Monte Carlo simulations. The agreement between experimental and our predicted estimations shows the good behavior of the proposed potentials. The developed potentials are able to properly describe both the microsolvation of clusters in gas phase and their hydration in aqueous solutions. The different nature of the interactions among F-, Br-, I- and water appears in the set of studied properties, thus giving a gradual change in the behavior along the group.Dirección General de Investigaciones Científicas y Técnicas BQU2002-0221

Billiards with polynomial mixing rates

While many dynamical systems of mechanical origin, in particular billiards, are strongly chaotic -- enjoy exponential mixing, the rates of mixing in many other models are slow (algebraic, or polynomial). The dynamics in the latter are intermittent between regular and chaotic, which makes them particularly interesting in physical studies. However, mathematical methods for the analysis of systems with slow mixing rates were developed just recently and are still difficult to apply to realistic models. Here we reduce those methods to a practical scheme that allows us to obtain a nearly optimal bound on mixing rates. We demonstrate how the method works by applying it to several classes of chaotic billiards with slow mixing as well as discuss a few examples where the method, in its present form, fails.Comment: 39pages, 11 figue

'The world is full of big bad wolves': investigating the experimental therapeutic spaces of R.D. Laing and Aaron Esterson

In conjunction with the recent critical assessments of the life and work of R.D. Laing, this paper seeks to demonstrate what is revealed when Laing’s work on families and created spaces of mental health care are examined through a geographical lens. The paper begins with an exploration of Laing’s time at the Tavistock Clinic in London during the 1960s, and of the co-authored text with Aaron Esterson entitled, Sanity, Madness and the Family (1964). The study then seeks to demonstrate the importance Laing and his colleague placed on the time-space situatedness of patients and their worlds. Finally, an account is provided of Laing’s and Esterson’s spatial thinking in relation to their creation of both real and imagined spaces of therapeutic care

Gut thinking: the gut microbiome and mental health beyond the head

Background: In recent decades, dominant models of mental illness have become increasingly focused on the head, with mental disorders being figured as brain disorders. However, research into the active role that the microbiome-gut-brain axis plays in affecting mood and behaviour may lead to the conclusion that mental health is more than an internalised problem of individual brains. Objective: This article explores the implications of shifting understandings about mental health that have come about through research into links between the gut microbiome and mental health problems such as depression and anxiety. It aims to analyse the different ways that the lines between mind and body and mental and physical health are re-shaped by this research, which is starting to inform clinical and public understanding. Design: As mental health has become a pressing issue of political and public concern it has become increasingly constructed in socio-cultural and personal terms beyond clinical spaces, requiring a conceptual response that exceeds biomedical inquiry. This article argues that an interdisciplinary critical medical humanities approach is well positioned to analyse the impact of microbiome-gut-brain research on conceptions of mind. Results: The entanglement of mind and matter evinced by microbiome-gut-brain axis research potentially provides a different way to conceptualise the physical and social concomitants of mental distress. Conclusion: Mental health is not narrowly located in the head but is assimilated by the physical body and intermingled with the natural world, requiring different methods of research to unfold the meanings and implications of gut thinking for conceptions of human selfhood

Two-Center Integrals for r_{ij}^{n} Polynomial Correlated Wave Functions

All integrals needed to evaluate the correlated wave functions with polynomial terms of inter-electronic distance are included. For this form of the wave function, the integrals needed can be expressed as a product of integrals involving at most four electrons