Isolation characteristics of space telescope suspension systems Final technical report

Vibration isolation tests of spring, hysteresis, and magnetic suspension systems for spaceborne telescope

What are women's mode of birth preferences and why? A systematic scoping review.

BACKGROUND:The optimal caesarean section rate is estimated to be between 10-15%; however, it is much higher in high and many middle-income countries and continues to be lower in some middle and low-income countries. While a range of factors influence caesarean section rates, women's mode of birth preferences also play a role. The aim of this study was to map the literature in relation to women's mode of birth preferences, and identify underlying reasons for, and factors associated with, these preferences. METHOD:Using a scoping review methodology, quantitative and qualitative evidence was systematically considered. To identify studies, PubMed, Maternity and Infant Care, MEDLINE, and Web of Science were searched for the period from 2008 to 2018, and reference lists of included studies were examined. FINDINGS:A total of 65 studies were included. While the majority of women prefer a vaginal birth, between 5-20% in high-income countries and 1.4 to 50% in low-middle-income countries prefer a caesarean section. The six main reasons or factors associated with a mode of birth preference were: (1) perceptions of safety; (2) fear of pain; (3) previous birth experience; (4) encouragement and dissuasion from health professionals; (5) social and cultural influences; and (6) access to information and educational levels. CONCLUSION:To help ensure women receive the required care that is aligned with their preferences, processes of shared decision-making should be implemented. Shared decision-making has the potential to reduce the rate of unnecessary interventions, and also improve the willingness of women to accept a medically-indicated caesarean section in low-income countries

What are women's mode of birth preferences and why? A systematic scoping review

Background: The optimal caesarean section rate is estimated to be between 10–15%; however, it is much higher in high and many middle-income countries and continues to be lower in some middle and low-income countries. While a range of factors influence caesarean section rates, women's mode of birth preferences also play a role. The aim of this study was to map the literature in relation to women's mode of birth preferences, and identify underlying reasons for, and factors associated with, these preferences. Method: Using a scoping review methodology, quantitative and qualitative evidence was systematically considered. To identify studies, PubMed, Maternity and Infant Care, MEDLINE, and Web of Science were searched for the period from 2008 to 2018, and reference lists of included studies were examined. Findings: A total of 65 studies were included. While the majority of women prefer a vaginal birth, between 5–20% in high-income countries and 1.4 to 50% in low-middle-income countries prefer a caesarean section. The six main reasons or factors associated with a mode of birth preference were: (1) perceptions of safety; (2) fear of pain; (3) previous birth experience; (4) encouragement and dissuasion from health professionals; (5) social and cultural influences; and (6) access to information and educational levels. Conclusion: To help ensure women receive the required care that is aligned with their preferences, processes of shared decision-making should be implemented. Shared decision-making has the potential to reduce the rate of unnecessary interventions, and also improve the willingness of women to accept a medically-indicated caesarean section in low-income countries

Exploring unwarranted clinical variation: The attitudes of midwives and obstetric medical staff regarding induction of labour and planned caesarean section

Background: Unexplained clinical variation is a major issue in planned birth i.e. induction of labour and planned caesarean section. Aim: To map attitudes and knowledge of maternity care professionals regarding indications for planned birth, and assess inter-professional (midwifery versus medical) and intra-professional variation. Methods: A custom-created survey of medical and midwifery staff at eight Sydney hospitals. Staff were asked to rate their level of agreement with 45 “evidence-based” statements regarding caesareans and inductions on a five-point Likert scale. Responses were grouped by profession, and comparisons made of inter- and intra-professional responses. Findings: Total 275 respondents, 78% midwifery and 21% medical. Considerable inter- and intra-professional variation was noted, with midwives generally less likely to consider any of the planned birth indications “valid” compared to medical staff. Indications for induction with most variation in midwifery responses included maternal characteristics (age≥40, obesity, ethnicity) and fetal macrosomia; and for medical personnel in-vitro fertilisation, maternal request, and routine induction at 39 weeks gestation. Indications for caesarean with most variation in midwifery responses included previous lower segment caesarean section, previous shoulder dystocia, and uncomplicated breech; and for medical personnel uncomplicated dichorionic twins. Indications with most inter-professional variation were induction at 41+ weeks versus 42+ weeks and cesarean for previous lower segment caesarean section. Discussion: Both inter- and intra-professional variation in what were considered valid indications reflected inconsistency in underlying evidence and/or guidelines. Conclusion: Greater focus on interdisciplinary education and consensus, as well as on shared decision-making with women, may be helpful in resolving these tensions

Time for Reading Instruction: How Much Time Should Schools and Teachers Devote to Reading Instruction in Grades K-2?

Although research has indicated that time allotted for instruction in reading is associated with reading achievement, no studies have examined what is the appropriate or optimal time that should be given to reading instruction in the primary grades (grades K-2). Given the understanding that it is the teachers themselves who would have the best sense of the appropriate time for reading instruction and its various components. Results of the survey indicate that teachers feel that 178-198 minutes be devoted to the general literacy curriculum, while 62-71 minutes be devoted to the core reading curriculum per day. We note that the allocation of time to the major components of reading instruction (word study, fluency, and comprehension) varied considerably. In follow-up survey inquiries, a significant number of teachers manifest difficulties in actually meeting their own recommendations for time appropriation for reading instruction. Among the factors that keep teachers from meeting their recommendations for instructional time are special events that disrupt and disturb the time given for instruction. Recommendations for making time for literacy instruction for effective and efficient are considered

Nuclear Octupole Correlations and the Enhancement of Atomic Time-Reversal Violation

We examine the time-reversal-violating nuclear ``Schiff moment'' that induces electric dipole moments in atoms. After presenting a self-contained derivation of the form of the Schiff operator, we show that the distribution of Schiff strength, an important ingredient in the ground-state Schiff moment, is very different from the electric-dipole-strength distribution, with the Schiff moment receiving no strength from the giant dipole resonance in the Goldhaber-Teller model. We then present shell-model calculations in light nuclei that confirm the negligible role of the dipole resonance and show the Schiff strength to be strongly correlated with low-lying octupole strength. Next, we turn to heavy nuclei, examining recent arguments for the strong enhancement of Schiff moments in octupole-deformed nuclei over that of 199Hg, for example. We concur that there is a significant enhancement while pointing to effects neglected in previous work (both in the octupole-deformed nuclides and 199Hg) that may reduce it somewhat, and emphasizing the need for microscopic calculations to resolve the issue. Finally, we show that static octupole deformation is not essential for the development of collective Schiff moments; nuclei with strong octupole vibrations have them as well, and some could be exploited by experiment.Comment: 25 pages, 4 figures embedded in tex

Diverse capacity for 2-methylhopanoid production correlates with a specific ecological niche

Molecular fossils of 2-methylhopanoids are prominent biomarkers in modern and ancient sediments that have been used as proxies for cyanobacteria and their main metabolism, oxygenic photosynthesis. However, substantial culture and genomic-based evidence now indicates that organisms other than cyanobacteria can make 2-methylhopanoids. Because few data directly address which organisms produce 2-methylhopanoids in the environment, we used metagenomic and clone library methods to determine the environmental diversity of hpnP, the gene encoding the C-2 hopanoid methylase. Here we show that hpnP copies from alphaproteobacteria and as yet uncultured organisms are found in diverse modern environments, including some modern habitats representative of those preserved in the rock record. In contrast, cyanobacterial hpnP genes are rarer and tend to be localized to specific habitats. To move beyond understanding the taxonomic distribution of environmental 2-methylhopanoid producers, we asked whether hpnP presence might track with particular variables. We found hpnP to be significantly correlated with organisms, metabolisms and environments known to support plant–microbe interactions (P-value<10^−6); in addition, we observed diverse hpnP types in closely packed microbial communities from other environments, including stromatolites, hot springs and hypersaline microbial mats. The common features of these niches indicate that 2-methylhopanoids are enriched in sessile microbial communities inhabiting environments low in oxygen and fixed nitrogen with high osmolarity. Our results support the earlier conclusion that 2-methylhopanoids are not reliable biomarkers for cyanobacteria or any other taxonomic group, and raise the new hypothesis that, instead, they are indicators of a specific environmental niche

The views of five participating undergraduate students of the Student Associates Scheme in England

This paper reports findings from a study which explored undergraduate perceptions of the Student Associates Scheme in England (SAS). The scheme was established by the Training and Development Agency for Schools in an attempt to increase the number of graduates entering the teaching profession, particularly in shortage subjects such as the physical sciences and mathematics. The scheme places undergraduate students on short-term placements in secondary schools throughout England to provide them with experiences that may encourage them to consider teaching as a career option. Findings show that the SAS school placements were a positive experience for the students participating in this study. However, a question emerged as to whether or not the scheme is targeting students who have yet to decide upon teaching as a career or just reinforcing the existing aspirations of students who have already decided to teach. As the scheme is attempting to increase the number of teachers entering the profession this question has important implications for this study and further work which will focus on undergraduates who think that their career ambitions would not be fulfilled by teaching

Microstructure and Structural Defects in MgB2 Superconductor

We report a detailed study of the microstructure and defects in sintered polycrystalline MgB2. Both TEM and x-ray data reveal that MgO is the major second-phase in our bulk samples. Although MgB2 and MgO have different crystal symmetries, being P6/mmm and Fm-3m, respectively, their stacking sequence of Mg and B (or O) and lattice spacings in certain crystallographic orientations are very similar. The size of MgO varies from 10~500nm, and its mismatch with the MgB2 matrix can be a source for dislocations. Dislocations in MgB2 often have a Burgers vector of . 1/3 and 1/3 partial dislocations and their associated stacking faults were also observed. Since both dislocations and stacking faults are located in the (001) basal plane, flux pinning anisotropy is expected. Diffuse scattering analysis suggests that the correlation length along the c-axis for defect-free basal planes is about 50nm. (001) twist grain-boundaries, formed by rotations along the c-axis, are major grain boundaries in MgB2 as a result of the out-of-plane weak bonding between Mg and B atoms. An excess of Mg was observed in some grain boundaries. High-resolution nano-probe EELS reveals that there is a difference in near edge structure of the boron K-edge acquired from grain boundaries and grain interiors. The change at the edge threshold may be suggestive of variation of the hole concentration that would significantly alter boundary superconductivity.Comment: 20 pages and 12 figure

Coupled-channels analysis of the 16^{{\bf 16}}O+208^{{\bf 208}}Pb fusion barrier distribution

Analyses using simplified coupled-channels models have been unable to describe the shape of the previously measured fusion barrier distribution for the doubly magic $^{16}$O+$^{208}$Pb system. This problem was investigated by re-measuring the fission excitation function for $^{16}$O+$^{208}$Pb with improved accuracy and performing more exact coupled-channels calculations, avoiding the constant-coupling and first-order coupling approximations often used in simplified analyses. Couplings to the single- and 2-phonon states of $^{208}$Pb, correctly taking into account the excitation energy and the phonon character of these states, particle transfers, and the effects of varying the diffuseness of the nuclear potential, were all explored. However, in contrast to other recent analyses of precise fusion data, no satisfactory simultaneous description of the shape of the experimental barrier distribution and the fusion cross-sections for $^{16}$O+$^{208}$Pb was obtained.Comment: RevTex, 29 pages, 7 postscript figures, to appear in PR