The fingerprint of the summer 2018 drought in Europe on ground-based atmospheric CO2 measurements

During the summer of 2018, a widespread drought developed over Northern and Central Europe. The increase in temperature and the reduction of soil moisture have influenced carbon dioxide (CO₂) exchange between the atmosphere and terrestrial ecosystems in various ways, such as a reduction of photosynthesis, changes in ecosystem respiration, or allowing more frequent fires. In this study, we characterize the resulting perturbation of the atmospheric CO₂ seasonal cycles. 2018 has a good coverage of European regions affected by drought, allowing the investigation of how ecosystem flux anomalies impacted spatial CO₂ gradients between stations. This density of stations is unprecedented compared to previous drought events in 2003 and 2015, particularly thanks to the deployment of the Integrated Carbon Observation System (ICOS) network of atmospheric greenhouse gas monitoring stations in recent years. Seasonal CO₂ cycles from 48 European stations were available for 2017 and 2018. Earlier data were retrieved for comparison from international databases or national networks. Here, we show that the usual summer minimum in CO₂ due to the surface carbon uptake was reduced by 1.4 ppm in 2018 for the 10 stations located in the area most affected by the temperature anomaly, mostly in Northern Europe. Notwithstanding, the CO₂ transition phases before and after July were slower in 2018 compared to 2017, suggesting an extension of the growing season, with either continued CO₂ uptake by photosynthesis and/or a reduction in respiration driven by the depletion of substrate for respiration inherited from the previous months due to the drought. For stations with sufficiently long time series, the CO₂ anomaly observed in 2018 was compared to previous European droughts in 2003 and 2015. Considering the areas most affected by the temperature anomalies, we found a higher CO₂ anomaly in 2003 (+3 ppm averaged over 4 sites), and a smaller anomaly in 2015 (+1 ppm averaged over 11 sites) compared to 2018. This article is part of the theme issue 'Impacts of the 2018 severe drought and heatwave in Europe: from site to continental scale'.

Coupling of emergent octahedral rotations to polarization in (K,Na)NbO3 ferroelectrics

Perovskite potassium sodium niobates, K_1−xNa_xNbO₃, are promising lead-free piezoelectrics. Their dielectric and piezoelectric characteristics peak near x = 0.5, but the reasons for such property enhancement remain unclear. We addressed this uncertainty by analyzing changes in the local and average structures across the x = 0.5 composition, which have been determined using simultaneous Reverse Monte Carlo fitting of neutron and X-ray total-scattering data, potassium EXAFS, and diffuse-scattering patterns in electron diffraction. Within the A-sites, Na cations are found to be strongly off-centered along the polar axis as a result of oversized cube-octahedral cages determined by the larger K ions. These Na displacements promote off-centering of the neighboring Nb ions, so that the Curie temperature and spontaneous polarization remain largely unchanged with increasing x, despite the shrinking octahedral volumes. The enhancement of the properties near x = 0.5 is attributed to an abrupt increase in the magnitude and probability of the short-range ordered octahedral rotations, which resembles the pre-transition behavior. These rotations reduce the bond tension around Na and effectively soften the short Na-O bond along the polar axis – an effect that is proposed to facilitate reorientation of the polarization as external electric field is applied.

Advancing reverse Monte Carlo structure refinements to the nanoscale

Over the past decade, theRMCProfilesoftware package has evolved into a powerful computational framework for atomistic structural refinements using a reverse Monte Carlo (RMC) algorithm and multiple types of experimental data. However, realizing the full potential of this method, which can provide a consistent description of atomic arrangements over several length scales, requires a computational speed much higher than that permitted by the current software. This problem has been addressedviasubstantial optimization and development ofRMCProfile, including the introduction of the new parallel-chains RMC algorithm. The computing speed of this software has been increased by nearly two orders of magnitude, as demonstrated using the refinements of a simulated structure with two distinct correlation lengths for the atomic displacements. The new developments provide a path for achieving even faster performance as more advanced computing hardware becomes available. This version ofRMCProfilepermits refinements of atomic configurations of the order of 500 000 atoms (compared to the current limit of 20 000), which sample interatomic distances up to 10 nm (versus3 nm currently). Accurate, computationally efficient corrections of the calculated X-ray and neutron total scattering data have been developed to account for the effects of instrumental resolution. These corrections are applied in both reciprocal and real spaces, thereby enabling RMC fitting of an atomic pair distribution function, which is obtained as the Fourier transform of the total-scattering intensity, over the entire nanoscale distance range accessible experimentally.

Conservative management of preterm premature rupture of membranes beyond 32 weeks' gestation: is it worthwhile?

We aimed to investigate whether conservative management of preterm premature rupture of membranes (PPROM) at 32-34 weeks' gestation improves outcome. In this retrospective analysis of singleton pregnancies, the study group included patients with PPROM at 28-34 weeks' gestation and the control group included patients presented with spontaneous preterm delivery at 28-34 weeks' gestation. Both groups were subdivided according to gestational age - early (28-31 weeks' gestation) versus late (32-34 weeks' gestation). Adverse neonatal outcome included neonatal death, intraventricular haemorrhage grade 3/4, respiratory distress syndrome, periventricular leucomalacia and neonatal sepsis. The study and control groups included 94 and 86 women, respectively. The study group had a lower incidence of adverse neonatal outcome at the earlier weeks (28-31), compared with the control group at the same gestational age. In contrast, at 32-34 weeks' gestation no difference in the risk for adverse neonatal outcome was noticed. Additionally, within the study group, chorioamnionitis rate was significantly higher among those who delivered at 32-34 weeks' gestation (p < 0.01). No advantage for conservative management of PPROM was demonstrated beyond 31 weeks' gestation. Moreover, conservative management of PPROM at 32-34 weeks' gestation may expose both mother and neonate to infectious morbidity.

Effect of cancer on ovarian function in patients undergoing in vitro fertilization for fertility preservation: a reappraisal

The past decade has witnessed an increase in cancer survival rates[...]

Elevated pretreatment levels of soluble CD8 and Beta-2-microglobulin as indicators of relapse in breast-cancer patients

We measured soluble CD8 ((S)CD8) and microglobulin (beta-2M) in 128 breast cancer patients and in 200 controls by the ELISA method. Patient groups were: Group A-new patients; Group B-patients on follow-up; Group C-patients with metastases. The mean (S)CD8 and beta-2M were significantly higher in patients than in controls ((S)CD8 p<0.01, beta-2M p<0.0001). Both for (S)CD8 and beta-2M, groups A and C had high levels which differed significantly from Group B ((S)CD8 p<0.04; beta-2M p<0.0001). A significant correlation between (S)CD8 and B-2M was observed (r=0.379: p=0.0001). Twenty patients relapsed. In 14/20 (70%) an initial high (S)CD8 and in 10/20 (50%), high beta-2M was observed. High initial CD8 and beta-2M were able to identify 80% of relapsed patients. High (S)CD8 and beta-2M levels are indicative of tumor bulk and are able to identify patients at.

Ultimate bending strength of Si nanowires

Test platforms for the ideal strength of materials are provided by almost defect-free nanostructures (nanowires, nanotubes, nanoparticles, for example). In this work, the ultimate bending strengths of Si nanowires with radii in the 20-60 nm range were investigated by using a new bending protocol. Nanowires simply held by adhesion on flat substrates were bent through sequential atomic force microscopy manipulations. The bending states prior to failure were analyzed in great detail to measure the bending dynamics and the ultimate fracture strength of the investigated nanowires. An increase in the fracture strengths from 12 to 18 GPa was observed as the radius of nanowires was decreased from 60 to 20 nm. The large values of the fracture strength of these nanowires, although comparable with the ideal strength of Si, are explained in terms of the surface morphology of the nanowires.

Placenta/birthweight ratio and perinatal outcome: a retrospective cohort analysis

OBJECTIVE

The placenta weight/birthweight (PW/BW) ratio has been shown to be associated with certain long-term fetal outcomes; however, its association with short-term outcomes has not received much attention. Our aim was to assess the correlation between the PW/BW ratio and short-term adverse obstetrics outcomes in full-term, appropriate-for-gestational-age (AGA) newborns.

DESIGN

Retrospective cohort study analysis using data from the McGill Obstetrical and Neonatal Database.

SETTING

McGill University Health Centre in Montreal Canada.

POPULATION

AGA neonates.

METHODS

Three groups of full-term AGA neonates were created, according to their PW/BW ratio (high, normal and low), to be compared. Our primary outcome was the admission rate to the neonatal intensive care unit (NICU), and secondary outcomes included an Apgar score < 7 at 5 minutes, cord PH < 7.0, cord base excess (BE) ≤ 12, respiratory distress syndrome (RDS), patent ductus arteriosus (PDA), occurrence of apnoea episodes, breech presentation at delivery, caesarean section rate and status in discharge home. A logistic regression model was instituted to investigate the predictors for adverse obstetrics outcomes.

MAIN OUTCOME MEASURE

Admission to the NICU.

RESULTS

Compared with the group with normal PW/BW ratios, the high PW/BW ratio group was associated with increased rates of admission to the NICU, of Apgar scores < 7 at 5 minutes, of breech presentation and caesarean section. On the contrary, the low PW/BW ratio group showed decreased rates of NICU admission, breech presentation and caesarean section.

CONCLUSIONS

A high PW/BW ratio is significantly correlated with short-term adverse perinatal outcomes. This ratio may be used as a new and simple warning sign to predict the possibility of short-term health risks for newborns.

Placenta weight percentile curves for singleton and twins deliveries

OBJECTIVE

To establish updated placental percentile nomograms in a large North American population for singleton and twin gestations for the use of researchers and clinicians.

STUDY DESIGN

Data was extracted from our computerized registry; McGill Obstetrics and Neonatal Database (MOND). The registry includes all the obstetrical data on all deliveries at the McGill University, including placental weight, placental pathologies, maternal and perinatal complications. 20,635 singleton deliveries and 527 twin deliveries were included. Placental weight, gestational age at delivery, birth weight and gender were retrieved. Tables and figures for the 3rd,10th,25th, 50th, 75th 90th, and 97th percentile of placental weight by gestational age, placental weight by birth weight and placental to birth weight ratio by gestational age were produced.

RESULTS

Tables and figures are presented for placental percentiles curves according to gestational age, gestational weight and gender for singleton and twin deliveries. In addition, tables and figures are presented for the ratio of placental weight to birth weight.

CONCLUSIONS

Population percentile curves have been produced for placental weight and for the ratio of placental weight to birth weight to for singleton and twin deliveries.

CHANGES IN THE TISSUE SURROUNDING A GROWING TUMOR AND THE SIGNIFICANCE OF THE "PRECANCEROUS STATE."

An analysis of the results of the experiments reported in this investigation shows that the changes so frequently observed in tissues surrounding a growing tumor may be caused by different conditions. The development and growth of a malignant tumor depends upon a local interaction between tumor cells and organ cells. When the cells of a normal organ are capable of inhibiting tumor growth, then an impairment of the normal state of the parenchymatous cells of this particular organ is essential for the growth of the tumor. This "precancerous state" does not consist primarily of an inflammatory change in the adjacent connective tissue, as Ribbert and his followers maintain, but in a degeneration of the parenchymatous cells of the organ. If, in another instance, the cells of the normal organs are unable to inhibit the proliferation of the tumor cells, then no preparation of the cells of the organ for the tumor is necessary, i. e., no "precancerous state" is needed to enable the tumor to grow. On the other hand, the proliferating tumor cells injure normal cells, either mechanically or chemically, producing a condition that appears on superficial examination like that described as the "precancerous state." In reality, however, this condition is the resultant effect of the tumor growth and may be more correctly designated the "postcancerous state." In these conditions, then, von Hansemann's explanation of the phenomenon, and not Ribbert's, seems to be the correct one. Of still greater importance is the fact demonstrated in the last series of experiments; namely, that the general condition of resistance or immunity to cancer growth exerts a greater influence on the organism of the animal than any of the local conditions described above. The local resistance of a testicle to tumor growth in a generally susceptible animal may be overcome, but if an animal is made generally immune to the growth of cancer, neither the animal as a whole nor a single organ or tissue in it can be made susceptible to the growth of the tumor.

A combined fit of total scattering and extended X-ray absorption fine structure data for local-structure determination in crystalline materials

Reverse Monte Carlo (RMC) refinements of local structure using a simultaneous fit of X-ray/neutron total scattering and extended X-ray absorption fine structure (EXAFS) data were developed to incorporate an explicit treatment of both single- and multiple-scattering contributions to EXAFS. The refinement algorithm, implemented as an extension to the public domain computer softwareRMCProfile, enables accurate modeling of EXAFS over distances encompassing several coordination shells around the absorbing species. The approach was first tested on Ni, which exhibits extensive multiple scattering in EXAFS, and then applied to perovskite-like SrAl1/2Nb1/2O3. This compound crystallizes with a cubic double-perovskite structure but presents a challenge for local-structure determination using a total pair-distribution function (PDF) alone because of overlapping peaks of the constituent partial PDFs (e.g.Al—O and Nb—O or Sr—O and O—O). The results obtained here suggest that the combined use of the total scattering and EXAFS data provides sufficient constraints for RMC refinements to recover fine details of local structure in complex perovskites. Among other results, it was found that the probability density distribution for Sr in SrAl1/2Nb1/2O3adoptsTdpoint-group symmetry for the Sr sites, determined by the ordered arrangement of Al and Nb, as opposed to a spherical distribution commonly assumed in traditional Rietveld refinements.