Rate limitation within a single enzyme is directly related to enzyme intermediate levels.

AbstractThe extents to which different rate constants limit the steady-state rate of an isolated enzyme can be quantified as the control coefficients of those constants and elemental steps. We have found that the sum of the control coefficients of rate constants characterising unidirectional rates depleting a particular enzyme intermediate is equal to the concentration of that enzyme intermediate as a fraction of the total enzyme concentration. Together with simple measurements this powerful relation may be used (i) to estimate certain enzyme intermediate levels, in particular the free enzyme concentration, and (ii) to estimate the control coefficients of rate constants and steps

The Conway-Kochen argument and relativistic GRW models

In a recent paper, Conway and Kochen proposed what is now known as the "Free Will theorem" which, among other things, should prove the impossibility of combining GRW models with special relativity, i.e., of formulating relativistically invariant models of spontaneous wavefunction collapse. Since their argument basically amounts to a non-locality proof for any theory aiming at reproducing quantum correlations, and since it was clear since very a long time that any relativistic collapse model must be non-local in some way, we discuss why the theorem of Conway and Kochen does not affect the program of formulating relativistic GRW models.Comment: 16 pages, RevTe

Prognostic factors affecting outcomes in fistulating perianal Crohn's disease: a systematic review.

BACKGROUND: One in three patients with Crohn's disease will develop a perianal fistulae, and one third of these will achieve long-term healing or closure. A barrier to conducting well-designed clinical trials for these patients is a lack of understanding of prognostic factors. This systematic review sets out to identify factors associated with prognosis of perianal Crohn's fistulae. METHODS: This review was registered on the PROSPERO database (CRD42016050316) and conducted in line with PRISMA guidelines along a predefined protocol. English-language studies assessing baseline factors related to outcomes of fistulae treatment in adult patients were included. Searches were performed on MEDLINE and Embase databases. Screening of abstracts and full texts for eligibility was performed prior to extraction of data into predesigned forms. Bias was assessed using the QUIPS tool. RESULTS: Searches identified 997 papers. Following removal of duplicates and secondary searches, 923 were screened for inclusion. Forty-seven papers were reviewed at full-text level and 13, 2 of which were randomised trials, were included in the final qualitative review. Two studies reported distribution of Crohn's disease as a prognostic factor for healing. Two studies found that CARD15 mutations decreased response of fistulae to antibiotics. Complexity of fistulae anatomy was implicated in prognosis by 4 studies. CONCLUSIONS: This systematic review has identified potential prognostic markers, including genetic factors and disease behaviour. We cannot, however, draw robust conclusions from this heterogeneous group of studies; therefore, we recommend that a prospective cohort study of well-characterised patients with Crohn's perianal fistulae is undertaken

Effect of the momentum dependence of nuclear symmetry potential on the transverse and elliptic flows

In the framework of the isospin-dependent Boltzmann-Uehling-Uhlenbeck transport model, effect of the momentum dependence of nuclear symmetry potential on nuclear transverse and elliptic flows in the neutron-rich reaction $^{132}$Sn+$^{124}$Sn at a beam energy of 400 MeV/nucleon is studied. We find that the momentum dependence of nuclear symmetry potential affects the rapidity distribution of the free neutron to proton ratio, the neutron and the proton transverse flows as a function of rapidity. The momentum dependence of nuclear symmetry potential affects the neutron-proton differential transverse flow more evidently than the difference of neutron and proton transverse flows as well as the difference of proton and neutron elliptic flows. It is thus better to probe the symmetry energy by using the difference of neutron and proton flows since the momentum dependence of nuclear symmetry potential is still an open question. And it is better to probe the momentum dependence of nuclear symmetry potential by using the neutron-proton differential transverse flow and the rapidity distribution of the free neutron to proton ratio.Comment: 6 pages, 6 figures, to be published by EPJ

Magnetic field-dependent interplay between incoherent and Fermi liquid transport mechanisms in low-dimensional tau phase organic conductors

We present an electrical transport study of the 2-dimensional (2D) organic conductor tau-(P-(S,S)-DMEDT-TTF)_2(AuBr)_2(AuBr_2)_y (y = 0.75) at low temperatures and high magnetic fields. The inter-plane resistivity rho_zz increases with decreasing temperature, with the exception of a slight anomaly at 12 K. Under a magnetic field B, both rho_zz and the in-plane resistivity plane rho_xx show a pronounced negative and hysteretic magnetoresistance with Shubnikov de Haas (SdH)oscillations being observed in some (high quality)samples above 15 T. Contrary to the predicted single, star-shaped, closed orbit Fermi surface from band structure calculations (with an expected approximate area of 12.5% of A_FBZ), two fundamental frequencies F_l and F_h are detected in the SdH signal. These orbits correspond to 2.4% and 6.8% of the area of the first Brillouin zone(A_FBZ), with effective masses F_l = 4.0 +/- 0.5 and F_h = 7.3 +/- 0.1. The angular dependence, in tilted magnetic fields of F_l and F_h, reveals the 2D character of the FS and Angular dependent magnetoresistance (AMRO) further suggests a FS which is strictly 2-D where the inter-plane hopping t_c is virtually absent or incoherent. The Hall constant R_xy is field independent, and the Hall mobility increases by a factor of 3 under moderate magnetic fields. Our observations suggest a unique physical situation where a stable 2D Fermi liquid state in the molecular layers are incoherently coupled along the least conducting direction. The magnetic field not only reduces the inelastic scattering between the 2D metallic layers, but it also reveals the incoherent nature of interplane transport in the AMRO spectrum. The apparent ferromagnetism of the hysteretic magnetoresistance remains an unsolved problem.Comment: 33 pages, 11 figure

The mixed problem in L^p for some two-dimensional Lipschitz domains

We consider the mixed problem for the Laplace operator in a class of Lipschitz graph domains in two dimensions with Lipschitz constant at most 1. The boundary of the domain is decomposed into two disjoint sets D and N. We suppose the Dirichlet data, f_D has one derivative in L^p(D) of the boundary and the Neumann data is in L^p(N). We find conditions on the domain and the sets D and N so that there is a p_0>1 so that for p in the interval (1,p_0), we may find a unique solution to the mixed problem and the gradient of the solution lies in L^p

Explaining the unobserved: why quantum mechanics is not only about information

A remarkable theorem by Clifton, Bub and Halvorson (2003)(CBH) characterizes quantum theory in terms of information--theoretic principles. According to Bub (2004, 2005) the philosophical significance of the theorem is that quantum theory should be regarded as a ``principle'' theory about (quantum) information rather than a ``constructive'' theory about the dynamics of quantum systems. Here we criticize Bub's principle approach arguing that if the mathematical formalism of quantum mechanics remains intact then there is no escape route from solving the measurement problem by constructive theories. We further propose a (Wigner--type) thought experiment that we argue demonstrates that quantum mechanics on the information--theoretic approach is incomplete.Comment: 34 Page

The UK risk assessment scheme for all non-native species

1. A pest risk assessment scheme, adapted from the EPPO (European and Mediterranean Plant Protection Organisation) scheme, was developed to assess the risks posed to UK species, habitats and ecosystems by non-native taxa. 2. The scheme provides a structured framework for evaluating the potential for non-native organisms, whether intentional or unintentional introductions, to enter, establish, spread and cause significant impacts in all or part of the UK. Specialist modules permit the relative importance of entry pathways, the vulnerability of receptors and the consequences of policies to be assessed and appropriate risk management options to be selected. Spreadsheets for summarising the level of risk and uncertainty, invasive attributes and economic impact were created. In addition, new methods for quantifying economic impact and summarising risk and uncertainty were explored. 3. Although designed for the UK, the scheme can readily be applied elsewhere

Absence of resonant enhancements in some inclusive rates

A toy model is defined and solved perturbatively with the aim of examining some claimed "resonant" enhancements of certain reaction rates that enter popular models of leptogenesis. We find: a) that such enhancements are absent; and b) that the perturbative solution, as done correctly using finite- temperature field theory, is well defined without the "resumming" procedures found in the literature. The pathologies that led to the perceived need for these procedures are an artifact of uncritical use of weighted vacuum cross- sections in the determination of rates, without adequate attention to the effects of the medium upon the single particle states within it.Comment: 11 pages, no figures. Some typos corrected. More typos correcte