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

The calculation of total reaction cross sections induced by intermediate energy α\alpha-particles with BUU Model

The Boltzmann-Uehling-Uhlenbeck (BUU) Model, which includes the Fermi motion, the mean field, individual nucleon-nucleon (N-N) interactions and the Pauli blocking effect etc., is used to calculate the total reaction cross section $\sigma_R$ induced by $\alpha$-particles on different targets in the incident energy range from 17.4 to 48.1 MeV/u. The calculation result can reproduce the experimental data well. The nucleus-nucleus interaction radius parameter $r_0$ was extracted from experimental $\sigma_R$. It is found that $r_0$ becomes constant with increasing the mass number of target.Comment: 4 pages, 4 fig

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

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

Intermittent versus continuous electronic monitoring in labour: a randomised study

OBJECTIVE: To compare the efficacy in detecting signs of fetal hypoxia in labour of intermittent (I-group) versus continuous (C-group) electronic fetal monitoring in women with low or moderate risk factors for fetal distress. DESIGN: A prospective, randomised study. SETTING: A tertiary referral centre. SUBJECTS: Four thousand and forty-four parturients at low risk for obstetric complications with a reactive fetal heart rate admission test at arrival in labour. During the study period (October 5 1989 to May 31 1991), 5647 women were delivered in the labour ward. Of these, 1178 women (20.9%) were excluded because of high risk factors in pregnancy or at admission for labour, including women undergoing elective caesarean section. Of the remaining 4469 women 4044 (90.5%) were randomised to either intermittent (n = 2015) or continuous monitoring (n = 2029) during the first stage of labour. METHODS: In the C-group the fetal heart rate was recorded continuously with electronic fetal monitoring during the first stage of labour. In the I-group the fetal heart rate was recorded with electronic fetal monitoring for 10 to 30 min every 2 to 2.5 h during the first stage of labour, and the fetal heart rate was auscultated every 15 to 30 min in between recording periods. If complications occurred, recording was changed to continuous. In the second stage of labour all the women were monitored continuously. Umbilical cord artery acid-base status was assessed at birth. MAIN OUTCOME MEASURES: Duration of electronic fetal monitoring, rates of abnormal fetal heart rate patterns, caesarean section for fetal distress, acidosis in umbilical cord arterial blood at birth, Apgar scores of less than 7 at 1 or 5 min, and referrals to the neonatal intensive care unit. RESULTS: There were no significant differences between the study groups in the incidence of ominous fetal heart rate recordings: 6.3% (I-group) versus 6.6% (C-group), or the interval from arrival to first detected abnormal fetal heart rate, although the number of suspicious fetal heart rate patterns was higher in the C-group (28.6%) than in the I-group (24.6%). In the I-group electronic fetal monitoring was performed for (median monitoring time) 38.8% of the first stage of labour as compared with 78.6% in the C-group. The incidence of caesarean section for fetal distress was similarly low in both groups: 1.2% versus 1.0%. There were no significant differences in the immediate neonatal outcome in terms of umbilical artery pH, Apgar scores, or admissions to the neonatal care unit. CONCLUSIONS: Intermittent use of electronic fetal monitoring at regular intervals (with stethoscopic auscultation in between) appears to be as safe as continuous electronic fetal monitoring in low risk labours