A Generalized Circle Theorem on Zeros of Partition Function at Asymmetric First Order Transitions

We present a generalized circle theorem which includes the Lee-Yang theorem for symmetric transitions as a special case. It is found that zeros of the partition function can be written in terms of discontinuities in the derivatives of the free energy. For asymmetric transitions, the locus of the zeros is tangent to the unit circle at the positive real axis in the thermodynamic limit. For finite-size systems, they lie off the unit circle if the partition functions of the two phases are added up with unequal prefactors. This conclusion is substantiated by explicit calculation of zeros of the partition function for the Blume-Capel model near and at the triple line at low temperatures.Comment: 10 pages, RevTeX. To be published in PRL. 3 Figures will be sent upon reques

Transcranial Magnetic theta-burst stimulation of the human cerebellum distinguishes absolute, duration-based from relative, beat-based perception of subsecond time intervals

Cerebellar functions in two types of perceptual timing were assessed: the absolute (duration-based) timing of single intervals and the relative (beat-based) timing of rhythmic sequences. Continuous transcranial magnetic theta-burst stimulation (cTBS) was applied over the medial cerebellum and performance was measured adaptively before and after stimulation. A large and significant effect was found in the TBS (n = 12) compared to the SHAM (n = 12) group for single-interval timing but not for the detection of a regular beat or a deviation from it. The data support the existence of distinct perceptual timing mechanisms and an obligatory role of the cerebellum in absolute interval timing with a functional dissociation from relative timing of interval within rhythmic sequences based on a regular beat

P,T-Violating Nuclear Matrix Elements in the One-Meson Exchange Approximation

Expressions for the P,T-violating NN potentials are derived for $\pi$, $\rho$ and $\omega$ exchange. The nuclear matrix elements for $\rho$ and $\omega$ exchange are shown to be greatly suppressed, so that, under the assumption of comparable coupling constants, $\pi$ exchange would dominate by two orders of magnitude. The ratio of P,T-violating to P-violating matrix elements is found to remain approximately constant across the nuclear mass table, thus establishing the proportionality between time-reversal-violation and parity-violation matrix elements. The calculated values of this ratio suggest a need to obtain an accuracy of order $5 \times 10^{-4}$ for the ratio of the PT-violating to P-violating asymmetries in neutron transmission experiments in order to improve on the present limits on the isovector pion coupling constant.Comment: 17 pages, LaTeX, no figure

Distribution and density of the partition function zeros for the diamond-decorated Ising model

Exact renormalization map of temperature between two successive decorated lattices is given, and the distribution of the partition function zeros in the complex temperature plane is obtained for any decoration-level. The rule governing the variation of the distribution pattern as the decoration-level changes is given. The densities of the zeros for the first two decoration-levels are calculated explicitly, and the qualitative features about the densities of higher decoration-levels are given by conjecture. The Julia set associated with the renormalization map is contained in the distribution of the zeros in the limit of infinite decoration level, and the formation of the Julia set in the course of increasing the decoration-level is given in terms of the variations of the zero density.Comment: 8 pages,8figure

Quantum field theory of metallic spin glasses

We introduce an effective field theory for the vicinity of a zero temperature quantum transition between a metallic spin glass (``spin density glass'') and a metallic quantum paramagnet. Following a mean field analysis, we perform a perturbative renormalization-group study and find that the critical properties are dominated by static disorder-induced fluctuations, and that dynamic quantum-mechanical effects are dangerously irrelevant. A Gaussian fixed point is stable for a finite range of couplings for spatial dimensionality $d > 8$, but disorder effects always lead to runaway flows to strong coupling for $d \leq 8$. Scaling hypotheses for a {\em static\/} strong-coupling critical field theory are proposed. The non-linear susceptibility has an anomalously weak singularity at such a critical point. Although motivated by a perturbative study of metallic spin glasses, the scaling hypotheses are more general, and could apply to other quantum spin glass to paramagnet transitions.Comment: 16 pages, REVTEX 3.0, 2 postscript figures; version contains reference to related work in cond-mat/950412

The association of smoking and socioeconomic status on cutaneous melanoma: a population‐based, data‐linkage, case–control study

BACKGROUND: Previous studies have identified an inverse association between melanoma and smoking; however, data from population-based studies are scarce. OBJECTIVES: To determine the association between smoking and socioeconomic (SES) on the risk of development of melanoma. Furthermore, we sought to determine the implications of smoking and SES on survival. METHODS: We conducted a population-based case-control study. Cases were identified from the Welsh Cancer Intelligence and Surveillance Unit (WCISU) during 2000-2015 and controls from the general population. Smoking and SES were obtained from data linkage with other national databases. The association of smoking status and SES on the incidence of melanoma were assessed using binary logistic regression. Multivariate survival analysis was performed on a melanoma cohort using a Cox proportional hazard model using survival as the outcome. RESULTS: During 2000-2015, 9636 patients developed melanoma. Smoking data were obtained for 7124 (73·9%) of these patients. There were 26 408 controls identified from the general population. Smoking was inversely associated with melanoma incidence [odds ratio (OR) 0·70, 95% confidence interval (CI) 0·65-0·76]. Smoking was associated with an increased overall mortality [hazard ratio (HR) 1·30, 95% CI 1·09-1·55], but not associated with melanoma-specific mortality. Patients with higher SES had an increased association with melanoma incidence (OR 1·58, 95% CI 1·44-1·73). Higher SES was associated with an increased chance of both overall (HR 0·67, 95% CI 0·56-0·81) and disease-specific survival (HR 0·69, 95% CI 0·53-0·90). CONCLUSIONS: Our study has demonstrated that smoking appeared to be associated with reduced incidence of melanoma. Although smoking increases overall mortality, no association was observed with melanoma-specific mortality. Further work is required to determine if there is a biological mechanism underlying this relationship or an alternative explanation, such as survival bias. What's already known about this topic? Previous studies have been contradictory with both negative and positive associations between smoking and the incidence of melanoma reported. Previous studies have either been limited by publication bias because of selective reporting or underpowered. What does this study add? Our large study identified an inverse association between smoking status and melanoma incidence. Although smoking status was negatively associated with overall disease survival, no significant association was noted in melanoma-specific survival. Socioeconomic status remains closely associated with melanoma. Although higher socioeconomic populations are more likely to develop the disease, patients with lower socioeconomic status continue to have a worse prognosis

Realistic Equations of State for the Primeval Universe

Early universe equations of state including realistic interactions between constituents are built up. Under certain reasonable assumptions, these equations are able to generate an inflationary regime prior to the nucleosynthesis period. The resulting accelerated expansion is intense enough to solve the flatness and horizon problems. In the cases of curvature parameter \kappa equal to 0 or +1, the model is able to avoid the initial singularity and offers a natural explanation for why the universe is in expansion.Comment: 32 pages, 5 figures. Citations added in this version. Accepted EPJ

Reenacting sensorimotor features of drawing movements from friction sounds

International audienceEven though we generally don't pay attention to the friction sounds produced when we are writing or drawing, these sounds are recordable, and can even evoke the underlying gesture. In this paper, auditory perception of such sounds, and the internal representations they evoke when we listen to them, is considered from the sensorimotor learning point of view. The use of synthesis processes of friction sounds makes it possible to investigate the perceptual influence of each gestures parameter separately. Here, the influence of the velocity profile on the mental representation of the gesture induced by a friction sound was investigated through 3 experiments. The results reveal the perceptual relevance of this parameter, and particularly a specific morphology corresponding to biological movements, the so-called 1/3-power law. The experiments are discussed according to the sensorimotor theory and the invariant taxonomy of the ecological approach

The antiferromagnetic phi4 Model, I. The Mean-field Solution

Certain higher dimensional operators of the lagrangian may render the vacuum inhomogeneous. A rather rich phase structure of the phi4 scalar model in four dimensions is presented by means of the mean-field approximation. One finds para- ferro- ferri- and antiferromagnetic phases and commensurate-incommensurate transitions. There are several particles described by the same quantum field in a manner similar to the species doubling of the lattice fermions. It is pointed out that chiral bosons can be introduced in the lattice regularized theory.Comment: To appear in Phys. Rev.

Spanning forests and the q-state Potts model in the limit q \to 0

We study the q-state Potts model with nearest-neighbor coupling v=e^{\beta J}-1 in the limit q,v \to 0 with the ratio w = v/q held fixed. Combinatorially, this limit gives rise to the generating polynomial of spanning forests; physically, it provides information about the Potts-model phase diagram in the neighborhood of (q,v) = (0,0). We have studied this model on the square and triangular lattices, using a transfer-matrix approach at both real and complex values of w. For both lattices, we have computed the symbolic transfer matrices for cylindrical strips of widths 2 \le L \le 10, as well as the limiting curves of partition-function zeros in the complex w-plane. For real w, we find two distinct phases separated by a transition point w=w_0, where w_0 = -1/4 (resp. w_0 = -0.1753 \pm 0.0002) for the square (resp. triangular) lattice. For w > w_0 we find a non-critical disordered phase, while for w < w_0 our results are compatible with a massless Berker-Kadanoff phase with conformal charge c = -2 and leading thermal scaling dimension x_{T,1} = 2 (marginal operator). At w = w_0 we find a "first-order critical point": the first derivative of the free energy is discontinuous at w_0, while the correlation length diverges as w \downarrow w_0 (and is infinite at w = w_0). The critical behavior at w = w_0 seems to be the same for both lattices and it differs from that of the Berker-Kadanoff phase: our results suggest that the conformal charge is c = -1, the leading thermal scaling dimension is x_{T,1} = 0, and the critical exponents are \nu = 1/d = 1/2 and \alpha = 1.Comment: 131 pages (LaTeX2e). Includes tex file, three sty files, and 65 Postscript figures. Also included are Mathematica files forests_sq_2-9P.m and forests_tri_2-9P.m. Final journal versio