Rapidly rotating Rayleigh-Bénard convection with a tilted axis.

We numerically explore the dynamics of an incompressible fluid heated from below, bounded by free-slip horizontal plates and periodic lateral boundary conditions, subject to rapid rotation about a distant axis that is tilted with respect to the gravity vector. The angle ϕ between the rotation axis and the horizontal plane measures the tilting of the rotation axis; it can be taken as a proxy for latitude if we think of a local Cartesian representation of the convective dynamics in a rotating fluid shell. The results of the simulations indicate the existence of three different convective regimes, depending on the value of ϕ: (1) sheared, intermittent large-scale winds in the direction perpendicular to the plane defined by the gravity and rotation vectors, when rotation is "horizontal" (ϕ=0^{∘}); (2) a large-scale cyclonic vortex tilted along the rotation axis, when the angle between the rotation axis and the gravity vector is relatively small (ϕ between about 45^{∘} and 90^{∘}); and (3) a new intermediate regime characterized by vertically sheared large-scale winds perpendicular to both gravity and rotation. In this regime, the winds are organized in bands that are tilted along the rotation axis, with unit horizontal wave number in the plane defined by gravity and rotation at values of ϕ less than about 60^{∘}. This intermediate solution, studied for the first time in this work, is characterized by weaker vertical heat transport than the cases with large-scale vortices. For intermediate values of ϕ (between about 45^{∘} and 60^{∘}), the banded, sheared solution coexists with the large-scale vortex solution, with different initial conditions leading to one or the other dynamical behavior. A discussion of the possible implications of these results for the dynamics of rapidly rotating planetary atmospheres is provided.

The association between birth weight at term and long-term endocrine morbidity of the offspring.

OBJECTIVE: To investigate whether small-for-gestational-age (SGA) and large-for-gestational-age (LGA) birth weight at-term poses an increased risk for long-term pediatric endocrine morbidity. STUDY DESIGN: A retrospective population-based cohort study compared the incidence of long-term pediatric hospitalizations due to endocrine morbidity of singleton children born SGA, appropriate-for-gestational-age (AGA), and LGA at-term. A multivariate generalized estimating equation (GEE) logistic regression model analysis was used to control for confounders. RESULTS: During the study period, 235,614 deliveries met the inclusion criteria; of which 4.7% were SGA (n = 11,062), 91% were AGA (n = 214,249), and 4.3% were LGA neonates (n = 10,303). During the follow-up period, children born SGA or LGA at-term had a significantly higher rate of long-term endocrine morbidity. Using a multivariable GEE logistic regression model, controlling for confounders, being delivered SGA or LGA at-term was found to be an independent risk factor for long-term pediatric endocrine morbidity (Adjusted OR = 1.4; 95%CI = 1.1-1.8; p = .015 and aOR = 1.4; 95%CI = 1.1-1.8; p = .005, respectively). Specifically, LGA was found an independent risk factor for overweight and obesity (aOR = 1.7; 95%CI = 1.2-2.5; p = .001), while SGA was found an independent risk factor for childhood hypothyroidism (aOR = 3.2; 95%CI = 1.8-5.8; p = .001). CONCLUSIONS: Birth weight either SGA or LGA at-term is an independent risk factor for long-term pediatric endocrine morbidity.

Maternal Asthma Is an Independent Risk Factor for Long-Term Respiratory Morbidity of the Offspring.

OBJECTIVE: The objective of this study was to investigate whether maternal bronchial asthma increases the risk for long-term respiratory morbidity of the offspring. STUDY DESIGN: A population-based cohort study compared the incidence of long-term pediatric hospitalizations due to respiratory disease of the offspring of mothers with and without bronchial asthma. Deliveries occurred between the years 1991 and 2014 in a tertiary medical center. Congenital malformations as well as multiple pregnancies were excluded. Kaplan-Meier's survival curve was used to estimate cumulative incidence of respiratory morbidity. A multivariate generalized estimating equation (GEE) logistic regression model analysis was used to control for confounders. RESULTS: During the study period, 253,808 deliveries met the inclusion criteria; of which 1.3% were born to mothers with bronchial asthma (n = 3,411). During the follow-up period, children born to women with bronchial asthma had a significantly higher rate of long-term respiratory morbidity (odds ratio [OR] = 1.5; 95% confidence interval [CI] = 1.3-1.7; p < 0.001). Specifically, the rate of childhood asthma was higher among offspring of mothers with asthma (OR = 2.3; 95% CI = 1.8-2.9; p < 0.001). Children born to women with asthma had higher cumulative incidence of respiratory morbidity, using a Kaplan-Meier's survival curve (log-rank test; p < 0.001). Using two multivariable GEE logistic regression models, controlling for the time to event, maternal age, and gestational age at delivery, maternal bronchial asthma was found to be an independent risk factor for long-term respiratory disease of the offspring (adjusted OR = 1.6; 95% CI = 1.4-1.9; p < 0.001), and specifically for bronchial asthma (adjusted OR = 2.5; 95% CI = 1.9-3.1; p < 0.001). CONCLUSION: Maternal bronchial asthma is an independent risk factor for long-term respiratory morbidity of the offspring.

Prediction of microcephaly at birth using three reference ranges for fetal head circumference: can we improve prenatal diagnosis?

OBJECTIVE: To evaluate the prediction of microcephaly at birth (micB) using established and two new reference ranges for fetal head circumference (HC) and to assess whether integrating additional parameters can improve prediction. METHODS: Microcephaly in utero was defined as a fetal HC 3SD below the mean for gestational age according to Jeanty et al.'s reference range. The records of cases with fetal microcephaly (Fmic) were evaluated for medical history, imaging findings, biometry and postnatal examination/autopsy findings. Microcephaly was confirmed at birth (micB) by an occipitofrontal circumference (OFC) or a brain weight at autopsy 2SD below the mean for gestational age. The new INTERGROWTH-21(st) Project and a recent Israeli reference for fetal growth were applied for evaluation of the Fmic positive predictive value (PPV) for diagnosis of micB cases. Optimal HC cut-offs were determined for each of the new references with the aim of detecting all micB cases whilst minimizing the number of false positives found to have a normal HC at birth. We also assessed the difference between the Z-scores of the prenatal HC and the corresponding OFC at birth, the frequency of small-for-gestational age (SGA), decreased HC/abdominal circumference (AC) and HC/femur length (FL) ratios, the prevalence of associated malformations and family history. RESULTS: Forty-two fetuses were diagnosed as having Fmic according to the Jeanty reference, but micB was confirmed in only 24 (PPV, 57.1%). The optimal INTERGROWTH and Israeli reference HC cut-offs for micB diagnosis were mean - 3SD and mean - 2.3SD, resulting in a statistically non-significant improvement in PPV to 61.5% and 66.7%, respectively. The presence of a family history of microcephaly, SGA, associated malformations and application of stricter HC cut-offs resulted in a higher PPV of micB, although not statistically significant and with a concurrent increase in the number of false-negative results. The deviation of the HC from the mean, by all references, was significantly larger compared with the actual deviation of the OFC at birth, with mean differences between the corresponding Z-scores of -1.15, -1.95 and -0.74 for the Jeanty, INTERGROWTH and Israeli references, respectively. CONCLUSIONS: The evaluated reference ranges all result in considerable over-diagnosis of fetal microcephaly. The use of the two new HC reference ranges did not significantly improve micB prediction compared with that of Jeanty et al., whilst use of additional characteristics and stricter HC cut-offs could improve the PPV with an increase in false negatives. The postnatal OFC deviates significantly less from the mean compared with the prenatal HC, and we propose that adjustment for this would enable better prediction of the actual OFC deviation at birth. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

Generation of Large-Scale Winds in Horizontally Anisotropic Convection.

We simulate three-dimensional, horizontally periodic Rayleigh-Bénard convection, confined between free-slip horizontal plates and rotating about a distant horizontal axis. When both the temperature difference between the plates and the rotation rate are sufficiently large, a strong horizontal wind is generated that is perpendicular to both the rotation vector and the gravity vector. The wind is turbulent, large-scale, and vertically sheared. Horizontal anisotropy, engendered here by rotation, appears necessary for such wind generation. Most of the kinetic energy of the flow resides in the wind, and the vertical turbulent heat flux is much lower on average than when there is no wind.

On the bifurcation of species.

We propose and analyze a model of evolution of species based upon a general description of phenotypes in terms of a single quantifiable characteristic. In the model, species spontaneously arise as solitary waves whose members almost never mate with those in other species, according to the rules laid down. The solitary waves in the model bifurcate and we interpret such events as speciation. Our aim in this work is to determine whether a generic mathematical mechanism may be identified with this process of speciation. Indeed, there is such a process in our model: it is the Andronov homoclinic bifurcation. It is robust and is at the heart of the formation of new solitary waves, and thus (in our model) new species.

Pattern dynamics in a checkerboard map.

Differential equations often have solutions in the forms of trains of coherent structures such as pulses and antipulses. For such systems, the methods of singular perturbation theory permit the derivation of pattern maps that predict the sequence of spacings between successive pulses. Here we apply such a procedure to cases where two distinct kinds of pulse (or antipulse) may coexist in the system. In that case, direct application of the method leads to multivalued maps that make for complicated descriptions, especially when the succession of pulse types becomes chaotic. We show how this description may be simplified by using maps arrayed in checkerboard style to provide causal descriptions of both the successions of pulse spacings and the order in which the different kinds of pulse go by.

Continuum description of rarefied gas dynamics. II. The propagation of ultrasound.

The equations of fluid dynamics developed in Paper I [X. Chen, H. Rao, and E. A. Spiegel, Phys. Rev. E 64, 46308 (2001)] are applied to the study of the propagation of ultrasound waves. There is good agreement between the predicted propagation speed and experimental results for a wide range of Knudsen numbers.

Continuum description of rarefied gas dynamics. I. Derivation from kinetic theory.

We describe an asymptotic procedure for deriving continuum equations from the kinetic theory of a simple gas. As in the works of Hilbert, of Chapman, and of Enskog, we expand in the mean flight time of the constituent particles of the gas, but we do not adopt the Chapman-Enskog device of simplifying the formulas at each order by using results from previous orders. In this way, we are able to derive a new set of fluid dynamical equations from kinetic theory, as we illustrate here for the relaxation model for monatomic gases. We obtain a stress tensor that contains a dynamical pressure term (or bulk viscosity) that is process dependent and our heat current depends on the gradients of both temperature and density. On account of these features, the equations apply to a greater range of Knudsen number (the ratio of mean free path to macroscopic scale) than do the Navier-Stokes equations, as we see in the accompanying paper. In the limit of vanishing Knudsen number, our equations reduce to the usual Navier-Stokes equations with no bulk viscosity.

Identification of quantitative trait loci affecting reproduction in pigs.

The objective of this research was to identify chromosomal regions harboring QTL affecting reproduction in pigs. A three-generation resource population was developed by crossing low-indexing pigs from a randomly selected control line (C) with high-indexing pigs of a line selected for increased index of ovulation rate and embryonic survival (I). Differences between Lines I and C at Generation 10 were 6.7 ova and 3.3 fetuses at 50 d of gestation and 3.1 fully formed and 1.6 live pigs at birth. Phenotypic data were collected on F2 females, born in three replicates, for ovulation rate (n = 423), age at puberty (n = 295), litter size (n = 370), and number of nipples (n = 428). Litter-size data included number of fully formed, live, stillborn, and mummified pigs. Grandparent, F1, and F2 animals were genotyped for 151 microsatellite markers distributed across all 18 autosomes and the X chromosome. Genotypic data were available on 423 F2 females. Average spacing between markers was 19.3 Kosambi centimorgans. Calculations of logarithms of odds (LOD) scores were by least squares, and fixed effects for sire-dam combination and replicate were included in the models. Genome-wide significance level thresholds of 5% and 10% were calculated using a permutation approach. There was evidence (P < 0.05) for QTL affecting ovulation rate on SSC9, age at puberty on SSC7 and SSC8, number of nipples on SSC8 and SSC11, number of stillborn pigs on SSC5 and SSC13, and number of fully formed pigs on SSC11. There was evidence (P < 0.10) for additional QTL affecting age at puberty on SSC7, SSC8, and SSC12, number born live on SSC11, and number of nipples on SSC1, SSC6, and SSC7. Litter size is lowly heritable and sex-limited. Therefore, accuracy of selection for litter size may be enhanced by marker-assisted selection. Ovulation rate and age at puberty are laborious to measure, and thus marker-assisted selection may provide a practical and efficient method of selection.

Scaling regimes in the distribution of galaxies.

If we treat the galaxies in published redshift catalogues as point sets, we may determine the generalized dimensions of these sets by standard means, outlined here. For galaxy separations up to about 5 Mpc, we find the dimensions of the CfA galaxy set to be about 1.2, with only a modest indication of multifractality. For larger scales, out to about 30 Mpc, there is also good scaling with a dimension of about 1.8. For even larger scales, the data seem too sparse to be conclusive, but we fmd that the dimension is climbing as the scales increase. We report simulations that suggest a rationalization of such measurements, namely that in the intermediate range the scaling behavior is dominated by flat structures (pancakes) and that the results on the smallest scales are a reflection of the formation of density singularities.

Stellar oscillons.

We study the weakly nonlinear evolution of acoustic instability of a plane-parallel polytrope with thermal dissipation in the form of Newton's law of cooling. The most unstable horizontal wavenumbers form a band around zero and this permits the development of a nonlinear pattern theory leading to a complex Ginzburg-Landau equation (CGLE). Numerical solutions for a subcritical, quintic CGLE produce vertically oscillating, localized structures that resemble the oscillons observed in recent experiments of vibrated granular material.

Negative energy modes and gravitational instability of interpenetrating fluids.

We study the longitudinal instabilities of two interpenetrating fluids interacting only through gravity. When one of the constituents is of relatively low density, it is possible to have a band of unstable wavenumbers well separated from those involved in the usual Jeans instability. If the initial streaming is large enough, and there is no linear instability, the indefinite sign of the free energy has the possible consequence of explosive interactions between positive and negative energy modes in the nonlinear regime. The effect of dissipation on the negative energy modes is also examined.

Cosmic lacunarity.

The present distribution of galaxies in space is a remnant of their formation and interaction. On a large enough scale, we may represent the galaxies as a set of points and quantify the structures in this set by its generalized dimensions [Beck and Schlogl, Thermodynamics of Chaotic Systems (Cambridge University Press, Cambridge, 1986); Paladin and Vulpiani, Phys. Rep. 156, 147 (1987)]. The results of such evaluation are often taken to be evidence of a fractal (or multifractal) distribution of galaxies. However, those results, for some scales, may also reveal the presence of singularities formed in the gravitational processes that produce structure in the galaxy distribution. To try to make some decision about this issue, we look for the more subtle galactic lacunarity. We believe that this quantity is discernible in the currently available data and that it provides important evidence on the galaxy formation process. (c) 1997 American Institute of Physics.

Checkerboard maps.

When a map has one positive Lyapunov exponent, its attractors often look like multidimensional, Cantorial plates of spaghetti. What saves the situation is that there is a deterministic jumping from strand to strand. We propose to approximate such attractors as finite sets of K suitably prescribed curves, each parametrized by an interval. The action of the map on each attractor is then approximated by a map that takes a set of curves into itself, and we graph it on a KxK checkerboard as a discontinuous one-dimensional map that captures the quantitative dynamics of the original system when K is sufficiently large. (c) 1995 American Institute of Physics.

Forging computer links when you have no tools.

Are stand-alone computers standing between you and vital inventory records? Experts respond to a typical hospital scenario.

The TMJ scale and undetected brain tumors in patients with temporomandibular disorders.

The symptoms of non-temporomandibular disorders, including mass lesions of the central nervous system, may mimic or be masked by symptoms of temporomandibular disorders, and thus not be detected. The dentist must remain alert to this possibility and maintain a high level of suspicion. Three cases illustrate how the TMJ Scale was used in patients having internal derangements of the temporomandibular joints to screen for and detect non-temporomandibular disorders, which, on further evaluation or referral, led to the diagnosis of brain tumors that had not been detected previously.