Background
Interpregnancy interval (IPI) <6 months is a potentially modifiable risk factor for adverse perinatal health outcomes.
Objective
This systematic review evaluated the international ...literature on the risk of perinatal death associated with IPI.
Search strategy
Two independent reviewers screened titles and s identified in MEDLINE, EMBASE and Scopus from inception to 4 April 2019 (Prospero Registration #CRD42018092792).
Selection criteria
Studies were included if they provided a description of IPI measurement and perinatal death, including stillbirth and neonatal death.
Data collection and analysis
A narrative review was performed for all included studies. Random effects meta‐analysis was used to compare unadjusted odds of perinatal death associated with IPI <6 months and IPI ≥6 months. Analyses were performed by outcome of the preceding pregnancy and study location.
Main results
Of the 624 unique articles identified, 26 met the inclusion criteria. The pooled unadjusted odds ratio of perinatal death for IPI <6 months was 1.34 (95% CI 1.17–1.53) following a previous live birth, 0.85 (95% CI 0.73–0.99) following a previous miscarriage and 1.07 (95% CI 0.84–1.36) following a previous stillbirth compared with IPI ≥6 months. However, few high‐income country studies reported an association after adjustment. Fewer studies evaluated the impact of long IPI on perinatal death and what evidence was available showed mixed results.
Conclusions
Results suggest a possible association between short IPI and risk of perinatal death following a live birth, particularly in low‐ to middle‐income countries.
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Short IPI <6 months after a live birth was associated with greater risk of perinatal death than IPI ≥6 months.
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Short IPI <6 months after a live birth was associated with greater risk of perinatal death than IPI ≥6 months.
This article includes Author Insights, a video available at https://vimeo.com/rcog/authorinsights16303
The interplay of magnetic interactions, the dimensionality of the crystal structure and electronic correlations in producing superconductivity is one of the dominant themes in the study of the ...electronic properties of complex materials. Although magnetic interactions and two-dimensional structures were long thought to be detrimental to the formation of a superconducting state, they are actually common features of both the high transition-temperature (Tc) copper oxides and low-Tc material Sr2RuO4, where they appear to be essential contributors to the exotic electronic states of these materials. Here we report that the perovskite-structured compound MgCNi3 is superconducting with a critical temperature of 8 K. This material is the three-dimensional analogue of the LnNi2B2C family of superconductors, which have critical temperatures up to 16 K (ref. 2). The itinerant electrons in both families of materials arise from the partial filling of the nickel d-states, which generally leads to ferromagnetism as is the case in metallic Ni. The high relative proportion of Ni in MgCNi3 suggests that magnetic interactions are important, and the lower Tc of this three-dimensional compound-when compared to the LnNi2B2C family-contrasts with conventional ideas regarding the origins of superconductivity.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Natural killer (NK) cells are the most prevalent leukocyte population in the uterus during early pregnancy. Natural killer cells contribute to uterine vascular (spiral artery) remodeling in ...preparation for the increased demand on these vessels later in pregnancy. A second wave of spiral artery modification is directed by invasive trophoblast cells. The significance of the initial wave of NK-cell-mediated vascular remodeling in species exhibiting deep trophoblast invasion such as humans and rats is not known. The purpose of this study was to generate a genetic model of NK-cell deficiency in rats, and determine the consequences of NK-cell deficiency on spiral artery remodeling and reproductive outcomes. To accomplish this task, we utilized zinc finger nucleasemediated genome editing of the rat interleukin-15 (Il15) gene. Il15 encodes a cytokine required for NK-cell lineage development. Using this strategy, a founder rat was generated containing a frameshift deletion in Il15. Uteri of females harboring a homozygous mutation at the Il15 locus contained no detectable NK cells. NK-cell deficiency did not impact fetal growth or viability. However, NK-cell deficiency caused major structural changes to the placenta, including expansion of the junctional zone and robust, early-onset activation of invasive trophoblast-guided spiral artery remodeling. In summary, we successfully generated an NK-cell-deficient rat and showed, using thismodel, that NK cells dampen the extent of trophoblast invasion and delay trophoblast-directed spiral artery remodeling. This study furthers our understanding of the role of NK cells on uterine vascular remodeling, trophoblast invasion, and placental development. Summary Sentence Natural killer cells delay trophoblast invasion and trophoblast-directed spiral artery remodeling in rats.
Objective
To investigate the effect of interpregnancy interval (IPI) on preterm birth (PTB) according to whether the previous birth was preterm or term.
Design
Cohort study.
Setting
USA (California), ...Australia, Finland, Norway (1980–2017).
Population
Women who gave birth to first and second (n = 3 213 855) singleton livebirths.
Methods
Odds ratios (ORs) for PTB according to IPIs were modelled using logistic regression with prognostic score stratification for potential confounders. Within‐site ORs were pooled by random effects meta‐analysis.
Outcome measure
PTB (gestational age <37 weeks).
Results
Absolute risk of PTB for each IPI was 3–6% after a previous term birth and 17–22% after previous PTB. ORs for PTB differed between previous term and preterm births in all countries (P‐for‐interaction ≤ 0.001). For women with a previous term birth, pooled ORs were increased for IPI <6 months (OR 1.50, 95% CI 1.43–1.58); 6–11 months (OR 1.10, 95% CI 1.04–1.16); 24–59 months (OR 1.16, 95% CI 1.13–1.18); and ≥ 60 months (OR 1.72, 95%CI 1.60–1.86), compared with 18–23 months. For previous PTB, ORs were increased for <6 months (OR 1.30, 95% CI 1.18–1.42) and ≥60 months (OR 1.29, 95% CI 1.17–1.42), but were less than ORs among women with a previous term birth (P < 0.05).
Conclusions
Associations between IPI and PTB are modified by whether or not the previous pregnancy was preterm. ORs for short and long IPIs were higher among women with a previous term birth than a previous PTB, which for short IPI is consistent with the maternal depletion hypothesis. Given the high risk of recurrence and assuming a causal association between IPI and PTB, IPI remains a potentially modifiable risk factor for women with previous PTB.
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Short versus long interpregnancy intervals associated with higher ORs for preterm birth (PTB) after a previous PTB.
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Short versus long interpregnancy intervals associated with higher ORs for preterm birth (PTB) after a previous PTB.
The discovery of superconductivity at 39 K in magnesium diboride offers the possibility of a new class of low-cost, high-performance superconducting materials for magnets and electronic applications. ...This compound has twice the transition temperature of Nb3Sn and four times that of Nb-Ti alloy, and the vital prerequisite of strongly linked current flow has already been demonstrated. One possible drawback, however, is that the magnetic field at which superconductivity is destroyed is modest. Furthermore, the field which limits the range of practical applications-the irreversibility field H*(T)-is approximately 7 T at liquid helium temperature (4.2 K), significantly lower than about 10 T for Nb-Ti (ref. 6) and approximately 20 T for Nb3Sn (ref. 7). Here we show that MgB2 thin films that are alloyed with oxygen can exhibit a much steeper temperature dependence of H*(T) than is observed in bulk materials, yielding an H* value at 4.2 K greater than 14 T. In addition, very high critical current densities at 4.2 K are achieved: 1 MA cm-2 at 1 T and 105 A cm-2 at 10 T. These results demonstrate that MgB2 has potential for high-field superconducting applications.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Highlights • We compared adverse event information collected by text messages to telephone interview. • Response rate was 40% higher to text messages compared to telephone interview. • Women were ...more 60% more likely to report an adverse event by telephone interview. • Data collected by text message were significantly timelier. • Results indicate text messaging is a feasible method for rapid vaccine safety surveillance.
The discovery of superconductivity at 39 K in magnesium diboride, MgB2, raises many issues, a critical one being whether this material resembles a high-temperature copper oxide superconductor or a ...low-temperature metallic superconductor in terms of its behaviour in strong magnetic fields. Although the copper oxides exhibit very high transition temperatures, their in-field performance is compromized by their large anisotropy, the result of which is to restrict high bulk current densities to a region much less than the full magnetic-field-temperature (H-T) space over which superconductivity is found. Moreover, the weak coupling across grain boundaries makes transport current densities in untextured polycrystalline samples low and strongly sensitive to magnetic field. Here we report that, despite the multiphase, untextured, microscale, subdivided nature of our MgB2 samples, supercurrents flow throughout the material without exhibiting strong sensitivity to weak magnetic fields. Our combined magnetization, magneto-optical, microscopy and X-ray investigations show that the supercurrent density is mostly determined by flux pinning, rather than by the grain boundary connectivity. Our results therefore suggest that this new superconductor class is not compromized by weak-link problems, a conclusion of significance for practical applications if higher temperature analogues of this compound can be discovered.
Celotno besedilo
Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The National Oceanic and Atmospheric Administration (NOAA), National Centers for Coastal Ocean Science (NCCOS) Mussel Watch Program (MWP), conducts basin-wide monitoring and place-based assessments ...using
dreissenid
mussels as bioindicators of chemical contamination in the Laurentian Great Lakes. Polycyclic aromatic hydrocarbons (PAHs) body burden results for the period 2009–2018 were combined into one dataset from multiple MWP studies allowing for a robust characterization of PAH contamination. Patterns in PAH data were identified using descriptive statistics and machine learning techniques. Relationships between total PAH concentration in
dreissenid
mussel tissue, impervious surface percentages, and PAH relative concentration were identified and used to build a predictive model for the Great Lakes Basin. Significant positive correlation was identified by the Spearman’s rank correlation test between total PAH concentration and percent impervious surface. The findings support the paradigm that PAHs are primarily derived from land-based sources. Offshore and riverine locations had the lowest and highest median total PAH concentrations, respectively. PAH assemblages and ratios indicated that pyrogenic sources were more predominant than petrogenic sources and that PAHs at offshore sites exhibited relatively more weathering compared to inshore sites.
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