Goldstone mode singularities in O(n) models

Monte Carlo (MC) analysis of the Goldstone mode singularities for the transverse and the longitudinal correlation functions, behaving as G_{\perp}(k) \simeq ak^{-\lambda_{\perp}} and G_{\parallel}(k) \simeq bk^{-\lambda_{\parallel}} in the ordered phase at k -> 0, is performed in the three-dimensional O(n) models with n=2, 4, 10. Our aim is to test some challenging theoretical predictions, according to which the exponents \lambda_{\perp} and \lambda_{\parallel} are non-trivial (3/2<\lambda_{\perp}<2 and 0<\lambda_{\parallel}<1 in three dimensions) and the ratio bM^2/a^2 (where M is a spontaneous magnetization) is universal. The trivial standard-theoretical values are \lambda_{\perp}=2 and \lambda_{\parallel}=1. Our earlier MC analysis gives \lambda_{\perp}=1.955 \pm 0.020 and \lambda_{\parallel} about 0.9 for the O(4) model. A recent MC estimation of \lambda_{\parallel}, assuming corrections to scaling of the standard theory, yields \lambda_{\parallel} = 0.69 \pm 0.10 for the O(2) model. Currently, we have performed a similar MC estimation for the O(10) model, yielding \lambda_{\perp} = 1.9723(90). We have observed that the plot of the effective transverse exponent for the O(4) model is systematically shifted down with respect to the same plot for the O(10) model by \Delta \lambda_{\perp} = 0.0121(52). It is consistent with the idea that 2-\lambda_{\perp} decreases for large $n$ and tends to zero at n -> \infty. We have also verified and confirmed the expected universality of bM^2/a^2 for the O(4) model, where simulations at two different temperatures (couplings) have been performed.Comment: 8 pages, 5 figure

2021 Update of the International Council for Standardization in Haematology Recommendations for Laboratory Measurement of Direct Oral Anticoagulants

International audienceIn 2018, the International Council for Standardization in Haematology (ICSH) published a consensus document providing guidance for laboratories on measuring direct oral anticoagulants (DOACs). Since that publication, several significant changes related to DOACs have occurred, including the approval of a new DOAC by the Food and Drug Administration, betrixaban, and a specific DOAC reversal agent intended for use when the reversal of anticoagulation with apixaban or rivaroxaban is needed due to life-threatening or uncontrolled bleeding, andexanet alfa. In addition, this ICSH Working Party recognized areas where additional information was warranted, including patient population considerations and updates in point-of-care testing. The information in this manuscript supplements our previous ICSH DOAC laboratory guidance document. The recommendations provided are based on (1) information from peer-reviewed publications about laboratory measurement of DOACs, (2) contributing author's personal experience/expert opinion and (3) good laboratory practice

Corrections to finite-size scaling in the φ4\varphi^4 model on square lattices

Corrections to scaling in the two-dimensional (2D) scalar (Formula presented.) model are studied based on nonperturbative analytical arguments and Monte Carlo (MC) simulation data for different lattice sizes L ((Formula presented.)) and different values of the (Formula presented.) coupling constant (Formula presented.), i.e. (Formula presented.), 1, 10. According to our analysis, amplitudes of the nontrivial correction terms with the correction–to–scaling exponents (Formula presented.) become small when approaching the Ising limit ((Formula presented.)), but such corrections generally exist in the 2D (Formula presented.) model. Analytical arguments show the existence of corrections with the exponent (Formula presented.). The numerical analysis suggests that there exist also corrections with the exponent (Formula presented.) and, perhaps, also with the exponent about (Formula presented.), which are detectable at (Formula presented.). The numerical tests provide an evidence that the structure of corrections to scaling in the 2D (Formula presented.) model differs from the usually expected one in the 2D Ising model