Effects of flares on solar high-degree helioseismic acoustic mode amplitudes

Several attempts have been made to observe whether solar flares excite acoustic modes since Wolff (1972) suggested this possibility. We look for the impact of flares on the amplitude of solar acoustic modes and other effects that are also affecting the mode amplitude. Solar acoustic mode amplitudes are known to be sensitive to magnetic fields. As flares usually occur in the presence of strong magnetic fields and most likely are the by-product of magnetic reconnection, we show how the magnetic field in and around the flaring region affects the mode amplitude. The mode amplitudes were obtained using ring-diagram analysis, which was first applied to a single event, the largest flare in the space age (the `Halloween Flare', SOL2003-10-28T11:00), using MDI data. Then, using HMI data, the analysis was applied to the regions corresponding to the flares observed during the high activity phase of cycle 24 and that fall into two groups. These two groups consist of small (10-60 erg cm$^{-2}$ s$^{-1}$) and large ($>$1200 erg cm$^{-2}$ s$^{-1}$) peak-flux flares, based on the Heliophysics Event Knowledgebase (HEK). The first set is used as a comparison to the results of the strong flares in the second set. After applying several corrections in order to take into account several sources of bias, we did not find any amplification in the inferred mode amplitude due to flaring activity larger than a 10% uncertainty.Comment: Submitted to MNRA

Visualizing the Effect of an Electrostatic Gate with Angle-Resolved Photoemission Spectroscopy

Electrostatic gating is pervasive in materials science, yet its effects on the electronic band structure of materials has never been revealed directly by angle-resolved photoemission spectroscopy (ARPES), the technique of choice to non-invasively probe the electronic band structure of a material. By means of a state-of-the-art ARPES setup with sub-micron spatial resolution, we have investigated a heterostructure composed of Bernal-stacked bilayer graphene (BLG) on hexagonal boron nitride and deposited on a graphite flake. By voltage biasing the latter, the electric field effect is directly visualized on the valence band as well as on the carbon 1s core level of BLG. The band gap opening of BLG submitted to a transverse electric field is discussed and the importance of intralayer screening is put forward. Our results pave the way for new studies that will use momentum-resolved electronic structure information to gain insight on the physics of materials submitted to the electric field effect

The pre‐metastatic niche in lymph nodes: formation and characteristics

peer reviewe

Evidence of diversity and recombination in Arsenophonus symbionts of the Bemisia tabaci species complex

<p>Abstract</p> <p>Background</p> <p>Maternally inherited bacterial symbionts infecting arthropods have major implications on host ecology and evolution. Among them, the genus <it>Arsenophonus</it> is particularly characterized by a large host spectrum and a wide range of symbiotic relationships (from mutualism to parasitism), making it a good model to study the evolution of host-symbiont associations. However, few data are available on the diversity and distribution of <it>Arsenophonus</it> within host lineages. Here, we propose a survey on <it>Arsenophonus</it> diversity in whitefly species (Hemiptera), in particular the <it>Bemisia tabaci</it> species complex. This polyphagous insect pest is composed of genetic groups that differ in many ecological aspects. They harbor specific bacterial communities, among them several lineages of <it>Arsenophonus</it>, enabling a study of the evolutionary history of these bacteria at a fine host taxonomic level, in association to host geographical range and ecology.</p> <p>Results</p> <p>Among 152 individuals, our analysis identified 19 allelic profiles and 6 phylogenetic groups, demonstrating this bacterium's high diversity. These groups, based on <it>Arsenophonus</it> phylogeny, correlated with <it>B. tabaci</it> genetic groups with two exceptions reflecting horizontal transfers<it>.</it> None of three genes analyzed provided evidence of intragenic recombination, but intergenic recombination events were detected. A mutation inducing a STOP codon on one gene in a strain infecting one <it>B. tabaci</it> genetic group was also found. Phylogenetic analyses of the three concatenated loci revealed the existence of two clades of <it>Arsenophonus.</it> One, composed of strains found in other Hemiptera, could be the ancestral clade in whiteflies. The other, which regroups strains found in Hymenoptera and Diptera, may have been acquired more recently by whiteflies through lateral transfers.</p> <p>Conclusions</p> <p>This analysis of the genus <it>Arsenophonus</it> revealed a diversity within the <it>B. tabaci</it> species complex which resembles that reported on the larger scale of insect taxonomy. We also provide evidence for recombination events within the <it>Arsenophonus</it> genome and horizontal transmission of strains among insect taxa. This work provides further insight into the evolution of the <it>Arsenophonus</it> genome, the infection dynamics of this bacterium and its influence on its insect host's ecology.</p

Logic against Ghosts: Comparison of Two Proof Approaches for a List Module

International audienceModern verification projects continue to offer new challenges for formal verification. One of them is the linked list module of Contiki, a popular open-source operating system for the Internet of Things. It has a rich API and uses a particular list representation that make it different from the classical linked list implementations. Being widely used in the OS, the list module is critical for reliability and security. A recent work verified the list module using ghost arrays. This article reports on a new verification effort for this module. Realized in the Frama-C/Wp tool, the new approach relies on logic lists. A logic list provides a convenient high-level view of the linked list. The specifications of all functions are now proved faster and almost all automatically, only a small number of auxiliary lemmas and a couple of assertions being proved interactively in Coq. The proposed specifications are validated by proving a few client functions manipulating lists. During the verification, a more efficient implementation for one function was found and verified. We compare the new approach with the previous effort based on ghost arrays, and discuss the benefits and drawbacks of both techniques

Periostin in lymph node pre-metastatic niches governs lymphatic endothelial cell functions and metastatic colonization.

peer reviewedAlthough lymph node (LN) metastasis is an important prognostic parameter in cervical cancer, the tissue remodeling at a pre-metastatic state is poorly documented in LNs. We here identified periostin (POSTN) as a component of non-metastatic LNs by applying proteomic analyses and computerized image quantifications on LNs of patients with cervical cancer. We provide evidence for remarkable modifications of POSTN and lymphatic vessel distributions and densities in non-metastatic sentinel and metastatic human LNs, when compared to distant non-metastatic LNs. POSTN deposition at a pre-metastatic stage was demonstrated in a pre-clinical murine model (the ear sponge assay). Its expression by fibroblastic LN cells was assessed by in situ hybridization and in vitro cultures. In vitro, POSTN promoted lymphatic endothelial cell functions and tumor cell proliferation. Accordingly, the in vivo injection of recombinant POSTN together with VEGF-C boosted the lymphangiogenic response, while the metastatic potential of tumor cells was drastically reduced using a POSTN blocking antibody. This translational study also supports the existence of an unprecedented dialog "in cascade", between the primary tumor and the first pelvic nodal relay in early cervical cancer, and subsequently from pelvic LN to para-aortic LNs in locally advanced cervical cancers. Collectively, this work highlights the association of POSTN deposition with lymphangiogenesis in LNs, and provides evidence for a key contribution of POSTN in promoting VEGF-C driven lymphangiogenesis and the seeding of metastatic cells

Impact of liver tumour burden, alkaline phosphatase elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate: an analysis of the NETTER-1 study

Purpose: To assess the impact of baseline liver tumour burden, alkaline phosphatase (ALP) elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate. Methods: In the phase 3 NETTER-1 trial, patients with advanced, progressive midgut neuroendocrine tumours (NET) were randomised to 177Lu-Dotatate (every 8 weeks, four cycles) plus octreotide long-acting release (LAR) or to octreotide LAR 60 mg. Primary endpoint was progression-free survival (PFS). Analyses of PFS by baseline factors, including liver tumour burden, ALP elevation, and target lesion size, were performed using Kaplan-Meier estimates; hazard ratios (HRs) with corresponding 95% CIs were estimated using Cox regression. Results: Significantly prolonged median PFS occurred with 177Lu-Dotatate versus octreotide LAR 60 mg in patients with low ( 50%) liver tumour burden (HR 0.187, 0.216, 0.145), and normal or elevated ALP (HR 0.153, 0.177), and in the presence or absence of a large target lesion (diameter > 30 mm; HR, 0.213, 0.063). Within the 177Lu-Dotatate arm, no significant difference in PFS was observed amongst patients with low/moderate/high liver tumour burden (P = 0.7225) or with normal/elevated baseline ALP (P = 0.3532), but absence of a large target lesion was associated with improved PFS (P = 0.0222). Grade 3 and 4 liver function abnormalities were rare and did not appear to be associated with high baseline liver tumour burden. Conclusions: 177Lu-Dotatate demonstrated significant prolongation in PFS versus high-dose octreotide LAR in patients with advanced, progressive midgut NET, regardless of baseline liver tumour burden, elevated ALP, or the presence of a large target lesion. Clinicaltrials.gov : NCT01578239, EudraCT: 2011-005049-11

Impact of liver tumour burden, alkaline phosphatase elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate: an analysis of the NETTER-1 study

Purpose: To assess the impact of baseline liver tumour burden, alkaline phosphatase (ALP) elevation, and target lesion size on treatment outcomes with 177Lu-Dotatate. Methods: In the phase 3 NETTER-1 trial, patients with advanced, progressive midgut neuroendocrine tumours (NET) were randomised to 177Lu-Dotatate (every 8 weeks, four cycles) plus octreotide long-acting release (LAR) or to octreotide LAR 60 mg. Primary endpoint was progression-free survival (PFS). Analyses of PFS by baseline factors, including liver tumour burden, ALP elevation, and target lesion size, were performed using Kaplan-Meier estimates; hazard ratios (HRs) with corresponding 95% CIs were estimated using Cox regression. Results: Significantly prolonged median PFS occurred with 177Lu-Dotatate versus octreotide LAR 60 mg in patients with low ( 50%) liver tumour burden (HR 0.187, 0.216, 0.145), and normal or elevated ALP (HR 0.153, 0.177), and in the presence or absence of a large target lesion (diameter > 30 mm; HR, 0.213, 0.063). Within the 177Lu-Dotatate arm, no significant difference in PFS was observed amongst patients with low/moderate/high liver tumour burden (P = 0.7225) or with normal/elevated baseline ALP (P = 0.3532), but absence of a large target lesion was associated with improved PFS (P = 0.0222). Grade 3 and 4 liver function abnormalities were rare and did not appear to be associated with high baseline liver tumour burden. Conclusions: 177Lu-Dotatate demonstrated significant prolongation in PFS versus high-dose octreotide LAR in patients with advanced, progressive midgut NET, regardless of baseline liver tumour burden, elevated ALP, or the presence of a large target lesion. Clinicaltrials.gov: NCT01578239, EudraCT: 2011-005049-11

Sismologie stellaire (méthodes statistiques appliquées aux étoiles de type solaire)

Cette thèse a porté sur l'analyse des spectres de puissance des étoiles de type solaire observées par les missions Corot et Kepler. L'analyse des étoiles ciblées se révèle délicate car les pulsations sont de faibles intensités et à cause des propriétés intrinsèques des pulsations de certaines d entre elles. Des méthodes robustes d inférence des propriétés des modes stellaires ont été développées. Elles sont basées sur une approche Bayésienne d'analyse du signal, utilisant soit des méthodes d'échantillonnages par chaine de Markov (MCMC), soit des méthodes par maximum a posteriori (MAP). Trois problématiques sont abordées : comment identifier les modes de pulsations stellaires avec des séries temporelles à faible rapport signal sur bruit ? Comment extraire les paramètres des modes de pulsations stellaires sur un large ensemble d étoiles ? Quelle est la structure interne des étoiles observées ? Les capacités de mes méthodes sont démontrées sur la base de simulations et d'observations de 3 étoiles : le Soleil, HD49933 et HD181420. L'ajustement du spectre de puissance de HD49933 et HD181420 par méthode MCMC nous permet d'identifier les modes avec un degré élevé de confiance là où des méthodes plus classiques d analyse du signal échouent. Un des algorithmes développés montre qu'il est possible d'identifier automatiquement les modes de manière fiable. Enfin, des modèles de structure interne de HD49933 et de HD181420 d'après les observations sismiques sont présentés : on met en évidence par exemple la présence d'un cœur convectif au sein de ces étoiles.ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

High Altitude Drones for Science. Near space in the near future

International audienceSpace experiments require qualification of instruments and even in the case of nano-satellites, it is a long and expensive way to achieve a flight model. A new generation of high altitude vehicles, now entering an industrial phase, may offer an alternate access to near space. Such solar powered drones are able to fly in the stratosphere for much longer missions than stratospheric balloons. The purpose of this paper is to explore characteristics of the environment, conditions of flight, and define ways to take on board scientific instruments. Small payloads are expected, in the range of several units cubesats