Strong Interplay between Stripe Spin Fluctuations, Nematicity and Superconductivity in FeSe

Elucidating the microscopic origin of nematic order in iron-based superconducting materials is important because the interactions that drive nematic order may also mediate the Cooper pairing. Nematic order breaks fourfold rotational symmetry in the iron plane, which is believed to be driven by either orbital or spin degrees of freedom. However, as the nematic phase often develops at a temperature just above or coincides with a stripe magnetic phase transition, experimentally determining the dominant driving force of nematic order is difficult. Here, we use neutron scattering to study structurally the simplest iron-based superconductor FeSe, which displays a nematic (orthorhombic) phase transition at $T_s=90$ K, but does not order antiferromagnetically. Our data reveal substantial stripe spin fluctuations, which are coupled with orthorhombicity and are enhanced abruptly on cooling to below $T_s$. Moreover, a sharp spin resonance develops in the superconducting state, whose energy (~4 meV) is consistent with an electron boson coupling mode revealed by scanning tunneling spectroscopy, thereby suggesting a spin fluctuation-mediated sign-changing pairing symmetry. By normalizing the dynamic susceptibility into absolute units, we show that the magnetic spectral weight in FeSe is comparable to that of the iron arsenides. Our findings support recent theoretical proposals that both nematicity and superconductivity are driven by spin fluctuations.Comment: 19 pages, 8 figure

Angiotensin-converting enzyme I/D polymorphism and preeclampsia risk: evidence of small-study bias

BACKGROUND: Inappropriate activation of the renin-angiotensin system may play a part in the development of preeclampsia. An insertion/deletion polymorphism within the angiotensin-I converting enzyme gene (ACE-I/D) has shown to be reliably associated with differences in angiotensin-converting enzyme (ACE) activity. However, previous studies of the ACE-I/D variant and preeclampsia have been individually underpowered to detect plausible genotypic risks. METHODS AND FINDINGS: A prospective case-control study was conducted in 1,711 unrelated young pregnant women (665 preeclamptic and 1,046 healthy pregnant controls) recruited from five Colombian cities. Maternal blood was obtained to genotype for the ACE-I/D polymorphism. Crude and adjusted odds ratio (OR) and 95% confidence interval (CI) using logistic regression models were obtained to evaluate the strength of the association between ACE-I/D variant and preeclampsia risk. A meta-analysis was then undertaken of all published studies to February 2006 evaluating the ACE-I/D variant in preeclampsia. An additive model (per-D-allele) revealed a null association between the ACE-I/D variant and preeclampsia risk (crude OR = 0.95 [95% CI, 0.81-1.10]) in the new case-control study. Similar results were obtained after adjusting for confounders (adjusted per-allele OR = 0.90 [95% CI, 0.77-1.06]) and using other genetic models of inheritance. A meta-analysis (2,596 cases and 3,828 controls from 22 studies) showed a per-allele OR of 1.26 (95% CI, 1.07-1.49). An analysis stratified by study size showed an attenuated OR toward the null as study size increased. CONCLUSIONS: It is highly likely that the observed small nominal increase in risk of preeclampsia associated with the ACE D-allele is due to small-study bias, similar to that observed in cardiovascular disease. Reliable assessment of the origins of preeclampsia using a genetic approach may require the establishment of a collaborating consortium to generate a dataset of adequate size

Stochastic Expression of the Interferon-β Gene

The analysis of stochastic interferon-beta gene expression in virus-infected mammalian cells reveals that the levels of components required for virtually every step in the virus induction pathway are limiting

Conserved molecular interactions in centriole-to-centrosome conversion.

Centrioles are required to assemble centrosomes for cell division and cilia for motility and signalling. New centrioles assemble perpendicularly to pre-existing ones in G1-S and elongate throughout S and G2. Fully elongated daughter centrioles are converted into centrosomes during mitosis to be able to duplicate and organize pericentriolar material in the next cell cycle. Here we show that centriole-to-centrosome conversion requires sequential loading of Cep135, Ana1 (Cep295) and Asterless (Cep152) onto daughter centrioles during mitotic progression in both Drosophila melanogaster and human. This generates a molecular network spanning from the inner- to outermost parts of the centriole. Ana1 forms a molecular strut within the network, and its essential role can be substituted by an engineered fragment providing an alternative linkage between Asterless and Cep135. This conserved architectural framework is essential for loading Asterless or Cep152, the partner of the master regulator of centriole duplication, Plk4. Our study thus uncovers the molecular basis for centriole-to-centrosome conversion that renders daughter centrioles competent for motherhood.J.F., Z.L., S.S. and N.S.D. are supported from Programme Grant to D.M.G. from Cancer Research UK. H.R. is supported from MRC Programme Grant to D.M.G. J.F. thank the British Academy and the Royal Society for Newton International Fellowship and Z.L. thanks the Federation of European Biochemical Societies for the Long-Term postdoctoral Fellowship. The authors thank Nicola Lawrence and Alex Sossick for assistance with 3D-SIM.This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/ncb327

A Vision for Incorporating Environmental Effects into Nitrogen Management Decision Support Tools for U.S. Maize Production

Meeting crop nitrogen (N) demand while minimizing N losses to the environment has proven difficult despite significant field research and modeling efforts. To improve N management, several real-time N management tools have been developed with a primary focus on enhancing crop production. However, no coordinated effort exists to simultaneously address sustainability concerns related to N losses at field- and regional-scales. In this perspective, we highlight the opportunity for incorporating environmental effects into N management decision support tools for United States maize production systems by integrating publicly available crop models with grower-entered management information and gridded soil and climate data in a geospatial framework specifically designed to quantify environmental and crop production tradeoffs. To facilitate advances in this area, we assess the capability of existing crop models to provide in-season N recommendations while estimating N leaching and nitrous oxide emissions, discuss several considerations for initial framework development, and highlight important challenges related to improving the accuracy of crop model predictions. Such a framework would benefit the development of regional sustainable intensification strategies by enabling the identification of N loss hotspots which could be used to implement spatially explicit mitigation efforts in relation to current environmental quality goals and real-time weather conditions. Nevertheless, we argue that this long-term vision can only be realized by leveraging a variety of existing research efforts to overcome challenges related to improving model structure, accessing field data to enhance model performance, and addressing the numerous social difficulties in delivery and adoption of such tool by stakeholders

A Vision for Incorporating Environmental Effects into Nitrogen Management Decision Support Tools for U.S. Maize Production.

Meeting crop nitrogen (N) demand while minimizing N losses to the environment has proven difficult despite significant field research and modeling efforts. To improve N management, several real-time N management tools have been developed with a primary focus on enhancing crop production. However, no coordinated effort exists to simultaneously address sustainability concerns related to N losses at field- and regional-scales. In this perspective, we highlight the opportunity for incorporating environmental effects into N management decision support tools for United States maize production systems by integrating publicly available crop models with grower-entered management information and gridded soil and climate data in a geospatial framework specifically designed to quantify environmental and crop production tradeoffs. To facilitate advances in this area, we assess the capability of existing crop models to provide in-season N recommendations while estimating N leaching and nitrous oxide emissions, discuss several considerations for initial framework development, and highlight important challenges related to improving the accuracy of crop model predictions. Such a framework would benefit the development of regional sustainable intensification strategies by enabling the identification of N loss hotspots which could be used to implement spatially explicit mitigation efforts in relation to current environmental quality goals and real-time weather conditions. Nevertheless, we argue that this long-term vision can only be realized by leveraging a variety of existing research efforts to overcome challenges related to improving model structure, accessing field data to enhance model performance, and addressing the numerous social difficulties in delivery and adoption of such tool by stakeholders

Accelerating carbon uptake in the Northern Hemisphere: evidence from the interhemispheric difference of atmospheric CO2 concentrations

Previous studies have indicated that the regression slope between the interhemispheric difference (IHD) of CO2 mixing ratios and fossil fuel (FF) CO2 emissions was rather constant at about 0.5 ppm/Pg C yr−1 during 1957–2003. In this study, we found that the average regression slopes between the IHD of CO2 mixing ratios and IHD of FF emissions for 16 sites in the Northern Hemisphere (NH) decreased from 0.69±0.12 ppm/Pg C yr−1 during 1982–1991 to 0.37±0.06 ppm/Pg C yr−1 during 1996–2008 (IHD of CO2 defined as the differences between each site and the South Pole, SPO). The largest difference was found in summer and autumn. The change in the spatial distribution of FF emissions driven by fast increasing Asian emissions may explain the slope change at three sites located north of 60°N but not at the other sites. A 30-yr SF6 simulation with time-varying meteorology and constant emissions suggests no significant difference in the decadal average and seasonal variation of interhemispheric exchange time (τ ex) between the two periods. Based on the hemispheric net carbon fluxes derived from a two-box model, we attributed 75% of the regression slope decrease at NH sites south of 60°N to the acceleration of net carbon sink increase in the NH and 25% to the weakening of net carbon sink increase in the SH during 1996–2008. The growth rate of net carbon sink in the NH has increased by a factor of about three from 0.028±0.023 [mean±2σ] Pg C yr−2 during 1982–1991 to 0.093±0.033 Pg C yr−2 during 1996–2008, exceeding the percentage increase in the growth rate of IHD of FF emissions between the two periods (45%). The growth rate of net carbon sink in the SH has reduced 62% from 0.058±0.018 Pg C yr−2 during 1982–1991 to 0.022±0.012 Pg C yr−2 during 1996–2008

N.B.: When citing this work, cite the original article. Original publication:

Zhu et a

Idiotype‐Anti‐Idiotype Interactions of VHIX‐Coded Anti‐Progesterone and Anti‐Arsonate Antibodies: Comparison of Passive Haemagglutination and Radioimmunoassays

The reactivity and specificity of potyctonal and monoclonal anti‐idiotypic antibodies raised against monoclonal anti‐progesterone and anti‐arsonate antibodies have been studied by solid phase radioimmunoassay (RIA) with immobilized idiotype and by passive haemagglutination with idiotype‐coupled red cells. The sensitivity of the two methods was comparable, though some cross‐reactions were only detected by RIA. Passive haemagglutination was found to be especially suitable in screening for monoclonal anti‐idiotypes in hybridoma supernatants and ascites. and had advantages over RIA in detection of syngeneic anti‐idiotypes. Demonstration of binding site‐associated idiotopes was possible by haemagglutination inhibition. RIA and haemagglutination were used to investigate the idiotypic relationships between BALB/c antiprogesterone and anti‐arsonate monoclonal antibodies which share heavy chains encoded by VHIX variable region genes. Copyright © 1987, Wiley Blackwell. All rights reservedSCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe