Reconstructing ice-sheet accumulation rates at ridge B, East Antarctica

Understanding how ice sheets responded to past climate change is fundamental to forecasting how they will respond in the future. Numerical models calculating the evolution of ice sheets depend upon accumulation data, which are principally available from ice cores. Here, we calculate past rates of ice accumulation using internal layering. The englacial structure of the East Antarctic ice divide at ridge B is extracted from airborne ice-penetrating radar. The isochronous surfaces are dated at their intersection with the Vostok ice-core site, where the depth–age relationship is known. The dated isochrons are used as input to a one-dimensional ice-flow model to investigate the spatial accumulation distribution. The calculations show that ice-accumulation rates generally increase from Vostok lake towards ridge B. The western flank of the ice divide experiences markedly more accumulation than in the east. Further, ice accumulation increases northwards along the ice divide. The results also show the variability of accumulation in time and space around the ridge B ice divide over the last 124 000 years

Analysis of CMB polarization on an incomplete sky

The full sky cosmic microwave background polarization field can be decomposed into 'electric' and 'magnetic' components. Working in harmonic space we construct window functions that allow clean separation of the electric and magnetic modes from observations over only a portion of the sky. Our construction is exact for azimuthally symmetric patches, but should continue to perform well for arbitrary patches. From the window functions we obtain variables that allow for robust estimation of the magnetic component without risk of contamination from the probably much larger electric signal. For isotropic, uncorrelated noise the variables have a very simple diagonal noise correlation, and further analysis using them should be no harder than analysing the temperature field. For an azimuthally-symmetric patch, such as that obtained from survey missions when the galactic region is removed, the exactly-separated variables are fast to compute allowing us to estimate the magnetic signal that could be detected by the Planck satellite in the absence of non-galactic foregrounds. We also discuss the sensitivity of future experiments to tensor modes in the presence of a magnetic signal generated by weak lensing, and give lossless methods for analysing the electric polarization field in the case that the magnetic component is negligible.Comment: 27 pages, 8 figures. New appendix on weak signal detection and revised plots using a better statistic. Other changes to match version accepted by PRD. Sample source code now available at http://cosmologist.info/pola

CMB power spectrum parameter degeneracies in the era of precision cosmology

Cosmological parameter constraints from the CMB power spectra alone suffer several well-known degeneracies. These degeneracies can be broken by numerical artefacts and also a variety of physical effects that become quantitatively important with high-accuracy data e.g. from the Planck satellite. We study degeneracies in models with flat and non-flat spatial sections, non-trivial dark energy and massive neutrinos, and investigate the importance of various physical degeneracy-breaking effects. We test the CAMB power spectrum code for numerical accuracy, and demonstrate that the numerical calculations are accurate enough for degeneracies to be broken mainly by true physical effects (the integrated Sachs-Wolfe effect, CMB lensing and geometrical and other effects through recombination) rather than numerical artefacts. We quantify the impact of CMB lensing on the power spectra, which inevitably provides degeneracy-breaking information even without using information in the non-Gaussianity. Finally we check the numerical accuracy of sample-based parameter constraints using CAMB and CosmoMC. In an appendix we document recent changes to CAMB's numerical treatment of massive neutrino perturbations, which are tested along with other recent improvements by our degeneracy exploration results.Comment: 27 pages, 28 figures. Latest CAMB version available from http://camb.info/. Reduced number of figures, plot legend corrected and minor edits to match published versio

Resting and reactive frontal brain electrical activity (EEG) among a non-clinical sample of socially anxious adults: Does concurrent depressive mood matter?

A number of studies have noted that the pattern of resting frontal brain electrical activity (EEG) is related to individual differences in affective style in healthy infants, children, and adults and some clinical populations when symptoms are reduced or in remission. We measured self-reported trait shyness and sociability, concurrent depressive mood, and frontal brain electrical activity (EEG) at rest and in anticipation of a speech task in a non-clinical sample of healthy young adults selected for high and low social anxiety. Although the patterns of resting and reactive frontal EEG asymmetry did not distinguish among individual differences in social anxiety, the pattern of resting frontal EEG asymmetry was related to trait shyness after controlling for concurrent depressive mood. Individuals who reported a higher degree of shyness were likely to exhibit greater relative right frontal EEG activity at rest. However, trait shyness was not related to frontal EEG asymmetry measured during the speech-preparation task, even after controlling for concurrent depressive mood. These findings replicate and extend prior work on resting frontal EEG asymmetry and individual differences in affective style in adults. Findings also highlight the importance of considering concurrent emotional states of participants when examining psychophysiological correlates of personality

One-year outcomes after transcatheter insertion of an interatrial shunt device for the management of heart failure with preserved ejection fraction

Background—Heart failure with preserved ejection fraction has a complex pathophysiology and remains a therapeutic challenge. Elevated left atrial pressure, particularly during exercise, is a key contributor to morbidity and mortality. Preliminary analyses have demonstrated that a novel interatrial septal shunt device that allows shunting to reduce the left atrial pressure provides clinical and hemodynamic benefit at 6 months. Given the chronicity of heart failure with preserved ejection fraction, evidence of longer-term benefit is required. Methods and Results—Patients (n=64) with left ventricular ejection fraction ≥40%, New York Heart Association class II–IV, elevated pulmonary capillary wedge pressure (≥15 mm Hg at rest or ≥25 mm Hg during supine bicycle exercise) participated in the open-label study of the interatrial septal shunt device. One year after interatrial septal shunt device implantation, there were sustained improvements in New York Heart Association class (P<0.001), quality of life (Minnesota Living with Heart Failure score, P<0.001), and 6-minute walk distance (P<0.01). Echocardiography showed a small, stable reduction in left ventricular end-diastolic volume index (P<0.001), with a concomitant small stable increase in the right ventricular end-diastolic volume index (P<0.001). Invasive hemodynamic studies performed in a subset of patients demonstrated a sustained reduction in the workload corrected exercise pulmonary capillary wedge pressure (P<0.01). Survival at 1 year was 95%, and there was no evidence of device-related complications. Conclusions—These results provide evidence of safety and sustained clinical benefit in heart failure with preserved ejection fraction patients 1 year after interatrial septal shunt device implantation. Randomized, blinded studies are underway to confirm these observations

Fertilité des sols: conclusions du rapport sur l'état des sols de France

Les sols constituent une ressource naturelle non renouvelable. Leurs usages et leur devenir représentent un enjeu collectif majeur, tant pour les activités agricoles ou sylvicoles que pour la préservation de la qualité de notre environnement. Après dix ans de travaux, le Groupement d’Intérêt Scientifique sur les sols, le Gis Sol, a dressé le premier bilan scientifiquement quantifié de l’état des sols de France métropolitaine et d’Outre-mer dans un rapport sur l’état des sols de France publié en 2011. Ce rapport relève des points positifs mais également un certain nombre de préoccupations du point de vue de la fertilité. Les sols agricoles ne présentent pas d’évolution mesurable de leur acidité, ce quiindique une bonne gestion du pH à l’échelle nationale. Le rapport fait en revanche état de teneurs en phosphore relativement faibles pour de nombreux sols, et à l’inverse de situations d’excédents très préoccupantes en raison de son impact sur la qualité des eaux et l’eutrophisation des milieux. Il pose ainsi la question de la durabilité à long terme du système agricole actuel et celle d’une meilleure valorisation des effluents d’élevage. D’assez nombreuses situations pourraient également être susceptibles de provoquer des carences en oligo-éléments pour des cultures exigeantes. Enfin, une inquiétude majeure concerne la progression de l’artificialisation des sols, qui s’est accélérée durant la dernière décennie et occasionne des pertes importantes de sols agricoles.Soils are a non-renewable, natural resource. Their uses and their future represent, therefore, a collective issue for agricultural and forestry production, as well as for the preservation of our environment. After ten years of work, the “Groupement d’intérêt scientifique sur les sols”, the Gis Sol (Soils Scientific Interest Group) has presented the first appraisal of soil quality in mainland France and its overseas territories in a report on the state of the soils in France published in 2011. This appraisal shows evidence for positive points but also highlights some concerns regarding soil fertility. Agricultural soils do not show a measurable change in their acidity, thus indicating an efficient management of pH at a national level. On the other hand, the report shows relatively low phosphorus levels for numerous soils, and inversely situations of structural excess which remain very worrying due to its impact on water quality and on the eutrophication of the environments. It also raises the questionsof the long-term sustainability of current cultivation systems and of a better treatment of effluents from livestock farming. Numerous situations also seem to be incompatible, for certain oligo-elements, with demanding cultures. At last, a major concern is the development of soil sealing, which has accelerated over the last decade and is responsible for the loss of large areas of agricultural soils