Predicting cesarean section and uterine rupture among women attempting vaginal birth after prior cesarean section

<p><b>Background:</b> There is currently no validated method for antepartum prediction of the risk of failed vaginal birth after cesarean section and no information on the relationship between the risk of emergency cesarean delivery and the risk of uterine rupture.</p> <p><b>Methods and Findings:</b> We linked a national maternity hospital discharge database and a national registry of perinatal deaths. We studied 23,286 women with one prior cesarean delivery who attempted vaginal birth at or after 40-wk gestation. The population was randomly split into model development and validation groups. The factors associated with emergency cesarean section were maternal age (adjusted odds ratio [OR] = 1.22 per 5-y increase, 95% confidence interval [CI]: 1.16 to 1.28), maternal height (adjusted OR = 0.75 per 5-cm increase, 95% CI: 0.73 to 0.78), male fetus (adjusted OR = 1.18, 95% CI: 1.08 to 1.29), no previous vaginal birth (adjusted OR = 5.08, 95% CI: 4.52 to 5.72), prostaglandin induction of labor (adjusted OR = 1.42, 95% CI: 1.26 to 1.60), and birth at 41-wk (adjusted OR = 1.30, 95% CI: 1.18 to 1.42) or 42-wk (adjusted OR = 1.38, 95% CI: 1.17 to 1.62) gestation compared with 40-wk. In the validation group, 36% of the women had a low predicted risk of caesarean section (<20%) and 16.5% of women had a high predicted risk (>40%); 10.9% and 47.7% of these women, respectively, actually had deliveries by caesarean section. The predicted risk of caesarean section was also associated with the risk of all uterine rupture (OR for a 5% increase in predicted risk = 1.22, 95% CI: 1.14 to 1.31) and uterine rupture associated with perinatal death (OR for a 5% increase in predicted risk = 1.32, 95% CI: 1.02 to 1.73). The observed incidence of uterine rupture was 2.0 per 1,000 among women at low risk of cesarean section and 9.1 per 1,000 among those at high risk (relative risk = 4.5, 95% CI: 2.6 to 8.1). We present the model in a simple-to-use format.</p> <p><b>Conclusions:</b> We present, to our knowledge, the first validated model for antepartum prediction of the risk of failed vaginal birth after prior cesarean section. Women at increased risk of emergency caesarean section are also at increased risk of uterine rupture, including catastrophic rupture leading to perinatal death.</p&gt

Friedel oscillations in one-dimensional metals: from Luttinger's theorem to the Luttinger liquid

Charge density and magnetization density profiles of one-dimensional metals are investigated by two complementary many-body methods: numerically exact (Lanczos) diagonalization, and the Bethe-Ansatz local-density approximation with and without a simple self-interaction correction. Depending on the magnetization of the system, local approximations reproduce different Fourier components of the exact Friedel oscillations.Comment: 3 pages, 3 figures, Manuscript accepted by Journal of Magnetism and Magnetic Materials, special issue for LAWMMM 2007 conferenc

Was atmospheric CO2 capped at 1000ppm over the past 300 million years?

AbstractAtmospheric carbon dioxide concentration has shifted dynamically over the Phanerozoic according to mass balance models and the majority of proxy estimates. A new paleo-CO2 proxy method underpinned by mechanistic understanding of plant stomatal, isotopic and photosynthetic responses to CO2 has provocatively claimed that maximum paleoatmospheric CO2 was capped at 1000ppm for the majority of the past 300 million years. Here we evaluate the robustness of the new paleo-proxy CO2 model by testing its sensitivity to initial parameterization and to scaling factors employed to estimate paleophysiological function from anatomical and morphological traits. A series of sensitivity analyses find that the model is robust to modification in some of the constants employed, such as CO2 compensation point and mesophyll conductance, resulting in variability in paleo-CO2 estimates which are already accounted for in the error propagation of the model. We demonstrate high sensitivity in the model to key input parameters such as initial fossil plant assimilation rate, termed A0 and scaling factors used to estimate stomatal conductance from measurements of fossil stomata. Incorrect parameterization of A0 has resulted in under estimation of pCO2 by as much as 600ppm. Despite these uncertainties, our analysis highlights that the new mechanistic paleo-CO2 proxy of Franks et al. (2014) has significant potential to derive robust and more accurate CO2 estimates from fossil plant stomata, as long as parameterization of A0 is strongly justified with species appropriate morphological and anatomical data. We highlight methods that can be used to improve current estimates of fossil plant assimilation rates, reduce uncertainty associated with implementation of the Franks et al. (2014) model and importantly add to understanding of patterns of plant productivity over the Phanerozoic, for which there currently is no consensus

The Tensor to Scalar Ratio of Phantom Dark Energy Models

We investigate the anisotropies in the cosmic microwave background in a class of models which possess a positive cosmic energy density but negative pressure, with a constant equation of state w = p/rho < -1. We calculate the temperature and polarization anisotropy spectra for both scalar and tensor perturbations by modifying the publicly available code CMBfast. For a constant initial curvature perturbation or tensor normalization, we have calculated the final anisotropy spectra as a function of the dark energy density and equation of state w and of the scalar and tensor spectral indices. This allows us to calculate the dependence of the tensor-to-scalar ratio on w in a model with phantom dark energy, which may be important for interpreting any future detection of long-wavelength gravitational waves.Comment: 5 pages, 4 figure

Tunneling ``zero-bias'' anomaly in the quasi-ballistic regime

For the first time, we study the tunneling density of states (DOS) of the interacting electron gas beyond the diffusive limit. A strong correction to the DOS persists even at electron energies exceeding the inverse transport relaxation time, which could not be expected from the well-known Altshuler-Aronov-Lee (AAL) theory. This correction originates from the interference between the electron waves scattered by an impurity and by the Friedel oscillation this impurity creates. Account for such processes also revises the AAL formula for the DOS in the diffusive limit.Comment: 4 pages, 2 .eps figures, submitted to Phys. Rev. Let

Impurity Energy Level Within The Haldane Gap

An impurity bond $J{'}$ in a periodic 1D antiferromagnetic, spin 1 chain with exchange $J$ is considered. Using the numerical density matrix renormalization group method, we find an impurity energy level in the Haldane gap, corresponding to a bound state near the impurity bond. When $J{'}<J$ the level changes gradually from the edge of the Haldane gap to the ground state energy as the deviation $dev=(J-J{'})/J$ changes from 0 to 1. It seems that there is no threshold. Yet, there is a threshold when $J{'}>J$. The impurity level appears only when the deviation $dev=(J{'}-J)/J{'}$ is greater than $B_{c}$, which is near 0.3 in our calculation.Comment: Latex file,9 pages uuencoded compressed postscript including 4 figure

Impurity state in Haldane gap for S=1 Heisenberg antiferromagnetic chain with bond doping

Using a new impurity density matrix renormalization group scheme, we establish a reliable picture of how the low lying energy levels of a $S=1$ Heisenberg antiferromagnetic chain change {\it quantitatively} upon bond doping. A new impurity state gradually occurs in the Haldane gap as $J' < J$, while it appears only if $J'/J>\gamma_c$ with $1/\gamma_c=0.708$ as $J'>J$. The system is non-perturbative as $1\leq J'/J\leq\gamma_c$. This explains the appearance of a new state in the Haldane gap in a recent experiment on Y$_{2-x}$Ca$_x$BaNiO$_5$ [J.F. DiTusa, et al., Phys. Rev. Lett. 73 1857(1994)].Comment: 4 pages of uuencoded gzip'd postscrip

Pairing in Cu-O Models: Clues of Joint Electron-Phonon and Electron-Electron Interactions

We discuss a many-electron Hamiltonian with Hubbard-like repulsive interaction and linear coupling to the phonon branches, having the Cu-O plane of the superconducting cuprates as a paradigm. A canonical transformation extracts an effective two-body problem from the many-body theory. As a prototype system we study the \cu cluster, which yields electronic pairing in the Hubbard model; moreover, a standard treatment of the Jahn-Teller effect predicts distortions that destroy electronic pairing. Remarkably, calculations that keep all the electronic spectrum into account show that vibrations are likely to be synergic with electronic pairing, if the coupling to half-breathing modes predominates, as experiments suggest.Comment: 4 pages, 3 figures, accepted by Phys. Rev.