Fetal pH and postnatal adaptation in preterm vaginal deliveries

Peer Reviewe

Predicting total reaction cross sections for nucleon-nucleus scattering

Nucleon total reaction and neutron total cross sections to 300 MeV for 12C and 208Pb, and for 65 MeV spanning the mass range, are predicted using coordinate space optical potentials formed by full folding of effective nucleon-nucleon interactions with realistic nuclear ground state densities. Good to excellent agreement is found with existing data.Comment: 10 pages, 4 figure

Elastic and total reaction cross sections of oxygen isotopes in Glauber theory

We systematically calculate the total reaction cross sections of oxygen isotopes, $^{15-24}$O, on a $^{12}$C target at high energies using the Glauber theory. The oxygen isotopes are described with Slater determinants generated from a phenomenological mean-field potential. The agreement between theory and experiment is generally good, but a sharp increase of the reaction cross sections from ^{21}O to ^{23}O remains unresolved. To examine the sensitivity of the diffraction pattern of elastic scattering to the nuclear surface, we study the differential elastic-scattering cross sections of proton-^{20,21,23}O at the incident energy of 300 MeV by calculating the full Glauber amplitude.Comment: 9 pages, 8 figure

Formula for proton-nucleus reaction cross section at intermediate energies and its application

We construct a formula for proton-nucleus total reaction cross section as a function of the mass and neutron excess of the target nucleus and the proton incident energy. We deduce the dependence of the cross section on the mass number and the proton incident energy from a simple argument involving the proton optical depth within the framework of a black sphere approximation of nuclei, while we describe the neutron excess dependence by introducing the density derivative of the symmetry energy, L, on the basis of a radius formula constructed from macroscopic nuclear models. We find that the cross section formula can reproduce the energy dependence of the cross section measured for stable nuclei without introducing any adjustable energy dependent parameter. We finally discuss whether or not the reaction cross section is affected by an extremely low density tail of the neutron distribution for halo nuclei.Comment: 7 pages, 4 figures, added reference

Low-lying Proton Intruder State in 13B

The neturon rich nucleus 13B was studied via the proton transfer reaction 4He(12Be,13B \gamma) at 50AMeV. The known 4.83-MeV excited state was strongly populated and its spin and parity were assigned to 1/2+ by comparing the angular differential cross section data with DWBA calculations. This low-lying 1/2+ state is interpreted as a proton intruder state and indicates a deformation of the nucleus.Comment: 16 pages, 3 figure

Spallation reactions. A successful interplay between modeling and applications

The spallation reactions are a type of nuclear reaction which occur in space by interaction of the cosmic rays with interstellar bodies. The first spallation reactions induced with an accelerator took place in 1947 at the Berkeley cyclotron (University of California) with 200 MeV deuterons and 400 MeV alpha beams. They highlighted the multiple emission of neutrons and charged particles and the production of a large number of residual nuclei far different from the target nuclei. The same year R. Serber describes the reaction in two steps: a first and fast one with high-energy particle emission leading to an excited remnant nucleus, and a second one, much slower, the de-excitation of the remnant. In 2010 IAEA organized a worskhop to present the results of the most widely used spallation codes within a benchmark of spallation models. If one of the goals was to understand the deficiencies, if any, in each code, one remarkable outcome points out the overall high-quality level of some models and so the great improvements achieved since Serber. Particle transport codes can then rely on such spallation models to treat the reactions between a light particle and an atomic nucleus with energies spanning from few tens of MeV up to some GeV. An overview of the spallation reactions modeling is presented in order to point out the incomparable contribution of models based on basic physics to numerous applications where such reactions occur. Validations or benchmarks, which are necessary steps in the improvement process, are also addressed, as well as the potential future domains of development. Spallation reactions modeling is a representative case of continuous studies aiming at understanding a reaction mechanism and which end up in a powerful tool.Comment: 59 pages, 54 figures, Revie

Perinatal outcomes associated with low birth weight in a historical cohort

<p>Abstract</p> <p>Objective</p> <p>To identify perinatal outcomes associated with low birth weight (LBW).</p> <p>Methods</p> <p>A retrospective cohort study in a tertiary maternity hospital. Analysis of the database on 43,499 liveborn infants delivered between 1986 and 2004 with low (n = 6,477) and normal (n = 37,467) birth weight. Outcomes associated with LBW were identified through crude and adjusted risk ratio (RR) and 95%CI with bivariate and multivariate analysis. The main outcomes were: onset of labor, mode of delivery, indication for cesarean section; amniotic fluid, fetal heart rate pattern, Apgar score, somatic gestational age, gender and congenital malformation.</p> <p>Results</p> <p>LBW infants showed more frequently signs of perinatal compromise such as abnormal amniotic fluid volume (especially olygohydramnios), nonreassuring patterns of fetal heart rate, malformation, lower Apgar scores and lower gestational age at birth. They were associated with a greater risk of labor induction and cesarean delivery, but lower risk of forceps.</p> <p>Conclusion</p> <p>There was a clear association between LBW and unfavorable perinatal outcomes.</p

Predictions of total and total reaction cross sections for nucleon-nucleus scattering up to 300 MeV

Total reaction cross sections are predicted for nucleons scattering from various nuclei. Projectile energies to 300 MeV are considered. So also are mass variations of those cross sections at selected energies. All predictions have been obtained from coordinate space optical potentials formed by full folding effective two-nucleon (NN) interactions with one body density matrix elements (OBDME) of the nuclear ground states. Good comparisons with data result when effective NN interactions defined by medium modification of free NN t matrices are used. Coupled with analyses of differential cross sections, these results are sensitive to details of the model ground states used to describe nuclei

Elevated risk of stillbirth in males: systematic review and meta-analysis of more than 30 million births

Background Stillbirth rates have changed little over the last decade, and a high proportion of cases are unexplained. This meta-analysis examined whether there are inequalities in stillbirth risks according to sex. Methods A systematic review of the literature was conducted, and data were obtained on more than 30 million birth outcomes reported in observational studies. The pooled relative risk of stillbirth was estimated using random-effects models. Results The crude mean rate (stillbirths/1,000 total births) was 6.23 for males and 5.74 for females. The pooled relative risk was 1.10 (95% confidence interval (CI): 1.07-1.13). The attributable fraction in the whole population was 4.2% (95% CI: 3.70-4.63), and the attributable fraction among male fetuses was 7.8% (95% CI: 7.0-8.66). Study populations from countries with known sex-biased sex selection issues had anomalous stillbirth sex ratios and higher overall stillbirth risks than other countries, reflecting increased mortality among females. Conclusions Risk of stillbirth in males is elevated by about 10%. The population-attributable risk is comparable to smoking and equates to approximately 100,000 stillbirths per year globally. The pattern is consistent across countries of varying incomes. Given current difficulties in reducing stillbirth rates, work to understand the causes of excess male risk is warranted. We recommend that stillbirths are routinely recorded by sex. This will also assist in exposing prenatal sex selection as elevated or equal risks of stillbirth in females would be readily apparent and could therefore be used to trigger investigation

Behavior Problems in Relation to Sustained Selective Attention Skills of Moderately Preterm Children

Attention skills may form an important developmental mechanism. A mediation model was examined in which behavioral problems of moderately preterm and term children at school age are explained by attention performance. Parents and teachers completed behavioral assessments of 348 moderately preterm children and 182 term children at 8 years of age. Children were administered a test of sustained selective attention. Preterm birth was associated with more behavioral and attention difficulties. Gestational age, prenatal maternal smoking, and gender were associated with mothers’, fathers’, and teachers’ reports of children’s problem behavior. Sustained selective attention partially mediated the relationship between birth status and problem behavior. Development of attention skills should be an important focus for future research in moderately preterm children