Competing Universalities in Kardar-Parisi-Zhang (KPZ) Growth Models

We report on the universality of height fluctuations at the crossing point of two interacting (1+1)-dimensional Kardar-Parisi-Zhang (KPZ) interfaces with curved and flat initial conditions. We introduce a control parameter p as the probability for the initially flat geometry to be chosen and compute the phase diagram as a function of p. We find that the distribution of the fluctuations converges to the Gaussian orthogonal ensemble Tracy-Widom (TW) distribution for p0.5. For p=0.5 where the two geometries are equally weighted, the behavior is governed by an emergent Gaussian statistics in the universality class of Brownian motion. We propose a phenomenological theory to explain our findings and discuss possible applications in nonequilibrium transport and traffic flow.Comment: 5 pages, 6 figures, Phys. Rev. Lett. (2019) (accepted

An exactly solvable record model for rainfall

Daily precipitation time series are composed of null entries corresponding to dry days and nonzero entries that describe the rainfall amounts on wet days. Assuming that wet days follow a Bernoulli process with success probability $p$, we show that the presence of dry days induces negative correlations between record-breaking precipitation events. The resulting non-monotonic behavior of the Fano factor of the record counting process is recovered in empirical data. We derive the full probability distribution $P(R,n)$ of the number of records $R_n$ up to time $n$, and show that for large $n$, its large deviation form coincides with that of a Poisson distribution with parameter $\ln(p\,n)$. We also study in detail the joint limit $p \to 0$, $n \to \infty$, which yields a random record model in continuous time $t = pn$.Comment: 11 pages, 2 figures + 13 pages and 2 figures of supplemental materia

Spin correlation functions in random-exchange s=1/2 XXZ chains

The decay of (disorder-averaged) static spin correlation functions at T=0 for the one-dimensional spin-1/2 XXZ antiferromagnet with uniform longitudinal coupling $J\Delta$ and random transverse coupling $J\lambda_i$ is investigated by numerical calculations for ensembles of finite chains. At $\Delta=0$ (XX model) the calculation is based on the Jordan-Wigner mapping to free lattice fermions for chains with up to N=100 sites. At $\Delta \neq 0$ Lanczos diagonalizations are carried out for chains with up to N=22 sites. The longitudinal correlation function is found to exhibit a power-law decay with an exponent that varies with $\Delta$ and, for nonzero $\Delta$, also with the width of the $\lambda_i$-distribution. The results for the transverse correlation function show a crossover from power-law decay to exponential decay as the exchange disorder is turned on.Comment: RevTex manuscript (7 pages), 4 postscript figure

X-Rays from the Nearby Solitary Millisecond Pulsar PSR J0030+0451 - the Final ROSAT Observations

We report on X-ray observations of the solitary 4.8 ms pulsar PSR J0030+0451. The pulsar was one of the last targets observed in DEC-98 by the ROSAT PSPC. X-ray pulses are detected on a $4.5\sigma$ level and make the source the $11^{th}$ millisecond pulsar detected in the X-ray domain. The pulsed fraction is found to be $69\pm18$. The X-ray pulse profile is characterized by two narrow peaks which match the gross pulse profile observed at 1.4 GHz. Assuming a Crab-like spectrum the X-ray flux is in the range $f_x= 2-3\times 10^{-13}$ erg s$^{-1}$ cm$^{-2}$ ($0.1-2.4$ keV), implying an X-ray efficiency of $L_x/\dot{E}\sim 0.5-5 \times 10^{-3} (d/0.23 {kpc})^2$.Comment: Accepted for publication in Ap

Decay of superfluid currents in the interacting one-dimensional Bose gas

We examine the superfluid properties of a 1D Bose gas in a ring trap based on the model of Lieb and Liniger. While the 1D Bose gas has nonclassical rotational inertia and exhibits quantization of velocities, the metastability of currents depends sensitively on the strength of interactions in the gas: the stronger the interactions, the faster the current decays. It is shown that the Landau critical velocity is zero in the thermodynamic limit due to the first supercurrent state, which has zero energy and finite probability of excitation. We calculate the energy dissipation rate of ring currents in the presence of weak defects, which should be observable on experimental time scales.Comment: 5 pages, 4 figure

First Evaluation of an Index of Low Vagally-Mediated Heart Rate Variability as a Marker of Health Risks in Human Adults: Proof of Concept.

Multiple studies have demonstrated low vagally-mediated heart rate variability (HRV) being associated with a range of risk factors for heart disease and stroke, including inflammation, hyperglycemia, hyperlipidemia, and hypertension. Yet, no cut point exists that indicates elevated risk. In the present study we sought to identify a cut point-value for HRV that is associated with elevated risk across a range of known risk factors. METHODS:A total of 9550 working adults from 19 study sites took part in a health assessment that included measures of inflammation, hyperglycemia, hyperlipidemia, and hypertension and vagally-mediated HRV (Root mean square of successive differences between normal heartbeats (RMSSD)). Multiple age and sex adjusted logistic regressions were calculated per risk factor (normal versus clinical range), with RMSSD being entered in binary at different cut points ranging from 15-39 msec with a 2 msec increment. RESULTS:For daytime RMSSD, values below 25 ± 4 indicated elevated risk (odds ratios (OR) 1.5-3.5 across risk factors). For nighttime RMSSD, values below 29 ± 4 indicated elevated risk (OR 1.2-2.0). CONCLUSION:These results provide the first evidence that a single value of RMSSD may be associated with elevated risk across a range of established cardiovascular risk factors and may present an easy to assess novel marker of cardiovascular risk

Dissipation in a rotating frame: master equation, effective temperature and Lamb-shift

Motivated by recent realizations of microwave-driven nonlinear resonators in superconducting circuits, the impact of environmental degrees of freedom is analyzed as seen from a rotating frame. A system plus reservoir model is applied to consistently derive in the weak coupling limit the master equation for the reduced density in the moving frame and near the first bifurcation threshold. It turns out that additional interactions between momenta of system and bath appear which have been omitted in previous studies. Explicit expressions for the effective temperature and the Lamb-shift are given which for ohmic baths are in agreement with experimental findings, while for structured environments population inversion is predicted that may qualitatively explain recent observations.Comment: 7 pages, 5 figure

Application of the disposition model to breast cancer data

In this paper, we have presented the second level nesting of Bonney's disposition model (Bonney, 1998) and examined the implications of higher level nesting of the disposition model in relation to the dimension of the parameter space. We have also compared the performance of the disposition model with Cox's regression model (Cox, 1972). It has been observed that the disposition model has a very large number of unknown parameters, and is therefore limited by the method of estimation used. In the case of the maximum likelihood method, reasonable estimates are obtained if the number of parameters in the model is at most nine. This corresponds to about four to seven covariates. Since each covariate in Cox's model provides a parameter, it is possible to include more covariates in the regression analysis. On the other hand, as opposed to Cox's model, the disposition model is fitted with parameters to capture aggregation in families, if there should be any. The choice of a particular model should therefore depend on the available data set and the purpose of the statistical analysis. --Second level nesting,Proportional hazards model,Quadratic exponential form,Partial likelihood,Familial aggregation,Second-order methods,Marginal models,Conditional models

Enhanced binding and cold compression of nuclei due to admixture of antibaryons

We discuss the possibility of producing a new kind of nuclear system by putting a few antibaryons inside ordinary nuclei. The structure of such systems is calculated within the relativistic mean field model assuming that the nucleon and antinucleon potentials are related by the G parity transformation. The presence of antinucleons leads to decreasing vector potential and increasing scalar potential for the nucleons. As a result, a strongly bound system of high density is formed. Due to the significant reduction of the available phase space the annihilation probability might be strongly suppressed in such systems