Maximum principle preserving time implicit DGSEM for linear scalar hyperbolic conservation laws

We investigate the properties of the high-order discontinuous Galerkin spectral element method (DGSEM) with implicit backward-Euler time stepping for the approximation of hyperbolic linear scalar conservation equation in multiple space dimensions. We first prove that the DGSEM scheme in one space dimension preserves a maximum principle for the cell-averaged solution when the time step is large enough. This property however no longer holds in multiple space dimensions and we propose to use the flux-corrected transport limiting [Boris and Book, J. Comput. Phys., 11 (1973)] based on a low-order approximation using graph viscosity to impose a maximum principle on the cell-averaged solution. These results allow to use a linear scaling limiter [Zhang and Shu, J. Comput. Phys., 229 (2010)] in order to impose a maximum principle at nodal values within elements. Then, we investigate the inversion of the linear systems resulting from the time implicit discretization at each time step. We prove that the diagonal blocks are invertible and provide efficient algorithms for their inversion. Numerical experiments in one and two space dimensions are presented to illustrate the conclusions of the present analyses.Comment: 34 page

About the efficiency of partial replication to implement Distributed Shared Memory

Distributed Shared Memory abstraction (DSM) is traditionally realized through a distributed memory consistency system(MCS) on top of a message passing system. In this paper we analyze the impossibility of efficient partial replication implementation of causally consistent DSM. Efficiency is discussed in terms of control information that processes have to propagate to maintain consistency. We introduce the notions of share graph and hoop to model variable distribution and the concept of dependency chain to characterize processes that have to manage information about a variable even though they do not read or write that variable. Then, we weaken causal consistency to try to define new consistency criteria weaker enough to allow efficient partial replication implementations and strong enough to solve interesting problems. Finally, we prove that PRAM is such a criterion, and illustrate its power with the Bellman-Ford shortest path algorithm. / Les mémoires partagées réparties constituent une abstraction qui est traditionellement concrétisée par un système réparti de mémoire cohérente, au-dessus d'un système de communication par messages. Dans ce rapport, on analyse l'impossibilité d'avoir une implémentation efficace de mémoire partagée répartie à cohérence causale, basée sur la duplication partielle des variables. L'efficacité est envisagée en terme d'information contrôle qui doit être propagée pour assurer la cohérence. On introduit les notions de graphe de partage et d'arceau, qui modélisent la répartition des variables et la notion de chaîne de dépendance pour caractériser les processus qui doivent gérer des informations relatives à une variable dont ils ne possèdent pas de copie locale. Ensuite, on affaiblit le critère de cohérence causale, dans le but de déterminer un nouveau critère de cohérence qui soit suffisament faible pour permettre un implémentation efficace basée sur la duplication partielle, mais suffisament forte pour pouvoir résoudre des problèmes intéressants. Finalement, on prouve que le critère appelé PRAM satisfait ces exigences, et illustrons sa pertinence en montrant une implémentation de l'algorithme de plus court chemin de Bellman-Ford

SLALOM: An all-surface snow water path retrieval algorithm for the GPM microwave imager

This paper describes a new algorithm that is able to detect snowfall and retrieve the associated snow water path (SWP), for any surface type, using the Global Precipitation Measurement (GPM) Microwave Imager (GMI). The algorithm is tuned and evaluated against coincident observations of the Cloud Profiling Radar (CPR) onboard CloudSat. It is composed of three modules for (i) snowfall detection, (ii) supercooled droplet detection and (iii) SWP retrieval. This algorithm takes into account environmental conditions to retrieve SWP and does not rely on any surface classification scheme. The snowfall detection module is able to detect 83% of snowfall events including light SWP (down to 1 × 10−3 kg·m−2) with a false alarm ratio of 0.12. The supercooled detection module detects 97% of events, with a false alarm ratio of 0.05. The SWP estimates show a relative bias of −11%, a correlation of 0.84 and a root mean square error of 0.04 kg·m−2. Several applications of the algorithm are highlighted: Three case studies of snowfall events are investigated, and a 2-year high resolution 70°S–70°N snowfall occurrence distribution is presented. These results illustrate the high potential of this algorithm for snowfall detection and SWP retrieval using GMI

Breast augmentation via the abdominoplasty incision approach: a prospective study of 100 cases

INTRODUCTION: Pregnancy and obesity cause distension of the abdominal wall and produce changes in the shape and size of the breasts. Thus, the need of aesthetic improvement of the abdominal area is not uncommon, coinciding with the desire for breast augmentation. Performing mammoplasty via the abdominoplasty incision approach was first described in 1976. Because of the lack of prospective studies using this approach, we performed a series of dermolipectomy procedures using the abdominal incision to insert a pair of silicone gel breast implants. METHODS: In total, 100 consecutive patients were selected, with a mean age of 33 ± 2 years. Classic abdominoplasty was performed, and 2 tunnels were then made in the right and left hypochondria. After implant placement, the mammary fold was reconstructed using simple sutures with absorbable threads to attach the subcutaneous tissue to the aponeurosis. RESULTS: None of the following complications were observed: deep-vein thrombosis, cardiorespiratory or anesthetic complications, skin necrosis, visible bleeding, hematoma, or clinically detectable infection. The volume of the implants ranged from 280 to 450 mL (median, 350 mL). The mean operation time was 116 minutes. Reoperation was not necessary in any of the cases. The monitoring period ranged from 9 to 84 months (mean, 36 months). CONCLUSIONS: Breast augmentation via the abdominoplasty incision approach was demonstrated to be a reliable and simple technique, providing a new, scar-free alternative to mammary surgical procedures.INTRODUÇÃO: A gravidez e a obesidade causam distensão da parede abdominal e também produzem mudanças na forma e no tamanho das mamas. Assim, não é incomum a necessidade de melhoria estética da área abdominal, coincidindo com o desejo de aumento de mama. A mamoplastia utilizando a mesma incisão da abdominoplastia foi descrita pela primeira vez em 1976. Em decorrência da falta de estudos prospectivos empregando essa abordagem, os autores realizaram uma série de dermolipectomias usando a incisão abdominal para inserir o par de implantes mamários de silicone gel. MÉTODO: Cem pacientes consecutivas foram selecionadas, com média de idade de 33 ± 2 anos. A abdominoplastia clássica foi realizada e, em seguida, confeccionados 2 túneis sobre os hipocôndrios direito e esquerdo. Após colocação dos implantes, foi realizada reconstrução do sulco mamário com pontos simples usando fios absorvíveis, fixando o subcutâneo à aponeurose. RESULTADOS: Não houve nenhuma das seguintes complicações: trombose venosa profunda, complicações cardiorrespiratórias ou anestésicas, necrose de pele, sangramento visível, e hematoma ou infecção detectáveis clinicamente. O volume dos implantes variou de 280 ml a 450 ml (mediana de 350 ml). O tempo médio de operação foi de 116 minutos. Em nenhum caso foi necessária reoperação. O período de acompanhamento mínimo foi de 9 meses e máximo, de 84 meses (média de 36 meses). CONCLUSÕES: A técnica de aumento mamário por meio da incisão da abdominoplastia se mostrou confiável e simples, constituindo uma nova opção para a cirurgia mamária sem cicatriz nas mamas.Universidade Federal de São Paulo (UNIFESP) Escola Paulista de MedicinaUNIFESP-EPMUniversidade Cidade de São PauloUNIFESP, EPMSciEL

Optically Enhanced Solid-State ¹H NMR Spectroscopy

International audienceLow sensitivity is the primary limitation toextending nuclear magnetic resonance (NMR) techniques tomore advanced chemical and structural studies. Photochemicallyinduced dynamic nuclear polarization (photo-CIDNP) is an NMRhyperpolarization technique where light is used to excite a suitabledonor−acceptor system, creating a spin-correlated radical pairwhose evolution drives nuclear hyperpolarization. Systems thatexhibit photo-CIDNP in solids are not common, and this effecthas, up to now, only been observed for 13C and 15N nuclei.However, the low gyromagnetic ratio and natural abundance ofthese nuclei trap the local hyperpolarization in the vicinity of thechromophore and limit the utility for bulk hyperpolarization. Here,we report the first example of optically enhanced solid-state 1HNMR spectroscopy in the high-field regime. This is achieved viaphoto-CIDNP of a donor−chromophore−acceptor molecule in a frozen solution at 0.3 T and 85 K, where spontaneous spindiffusion among the abundant strongly coupled 1H nuclei relays polarization through the whole sample, yielding a 16-fold bulk 1Hsignal enhancement under continuous laser irradiation at 450 nm. These findings enable a new strategy for hyperpolarized NMRbeyond the current limits of conventional microwave-driven DNP

Mechanics of the IL2RA Gene Activation Revealed by Modeling and Atomic Force Microscopy

Transcription implies recruitment of RNA polymerase II and transcription factors (TFs) by DNA melting near transcription start site (TSS). Combining atomic force microscopy and computer modeling, we investigate the structural and dynamical properties of the IL2RA promoter and identify an intrinsically negative supercoil in the PRRII region (containing Elf-1 and HMGA1 binding sites), located upstream of a curved DNA region encompassing TSS. Conformational changes, evidenced by time-lapse studies, result in the progressive positioning of curvature apex towards the TSS, likely facilitating local DNA melting. In vitro assays confirm specific binding of the General Transcription Factors (GTFs) TBP and TFIIB over TATA-TSS position, where an inhibitory nucleosome prevented preinitiation complex (PIC) formation and uncontrolled DNA melting. These findings represent a substantial advance showing, first, that the structural properties of the IL2RA promoter are encoded in the DNA sequence and second, that during the initiation process DNA conformation is dynamic and not static

Outgassing Behavior of C/2012 S1 (ISON) From September 2011 to June 2013

We report photometric observations for comet C/2012 S1 (ISON) obtained during the time period immediately after discovery (r=6.28 AU) until it moved into solar conjunction in mid-2013 June using the UH2.2m, and Gemini North 8-m telescopes on Mauna Kea, the Lowell 1.8m in Flagstaff, the Calar Alto 1.2m telescope in Spain, the VYSOS-5 telescopes on Mauna Loa Hawaii and data from the CARA network. Additional pre-discovery data from the Pan STARRS1 survey extends the light curve back to 2011 September 30 (r=9.4 AU). The images showed a similar tail morphology due to small micron sized particles throughout 2013. Observations at sub-mm wavelengths using the JCMT on 15 nights between 2013 March 9 (r=4.52 AU) and June 16 (r=3.35 AU) were used to search for CO and HCN rotation lines. No gas was detected, with upper limits for CO ranging between (3.5-4.5)E27 molec/s. Combined with published water production rate estimates we have generated ice sublimation models consistent with the photometric light curve. The inbound light curve is likely controlled by sublimation of CO2. At these distances water is not a strong contributor to the outgassing. We also infer that there was a long slow outburst of activity beginning in late 2011 peaking in mid-2013 January (r~5 AU) at which point the activity decreased again through 2013 June. We suggest that this outburst was driven by CO injecting large water ice grains into the coma. Observations as the comet came out of solar conjunction seem to confirm our models.Comment: 8 pages, 2 figures, 3 table

Atomic force microscopy of DNA in solution and DNA modelling show that structural properties specify the eukaryotic replication initiation site

The replication origins (ORIs) of Schizosaccharomyces pombe, like those in most eukaryotes, are long chromosomal regions localized within A+T-rich domains. Although there is no consensus sequence, the interacting proteins are strongly conserved, suggesting that DNA structure is important for ORI function. We used atomic force microscopy in solution and DNA modelling to study the structural properties of the Spars1 origin. We show that this segment is the least stable of the surrounding DNA (9 kb), and contains regions of intrinsically bent elements (strongly curved and inherently supercoiled DNAs). The pORC-binding site co-maps with a superhelical DNA region, where the spatial arrangement of adenine/thymine stretches may provide the binding substrate. The replication initiation site (RIP) is located within a strongly curved DNA region. On pORC unwinding, this site shifts towards the apex of the curvature, thus potentiating DNA melting there. Our model is entirely consistent with the sequence variability, large size and A+T-richness of ORIs, and also accounts for the multistep nature of the initiation process, the specificity of pORC-binding site(s), and the specific location of RIP. We show that the particular DNA features and dynamic properties identified in Spars1 are present in other eukaryotic origins

Improving quality in nanoparticle-induced cytotoxicity testing by a tiered inter-laboratory comparison study

The quality and relevance of nanosafety studies constitute major challenges to ensure their key role as a supporting tool in sustainable innovation, and subsequent competitive economic advantage. However, the number of apparently contradictory and inconclusive research results has increased in the past few years, indicating the need to introduce harmonized protocols and good practices in the nanosafety research community. Therefore, we aimed to evaluate if best-practice training and inter-laboratory comparison (ILC) of performance of the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay for the cytotoxicity assessment of nanomaterials among 15 European laboratories can improve quality in nanosafety testing. We used two well-described model nanoparticles, 40-nm carboxylated polystyrene (PS-COOH) and 50-nm amino-modified polystyrene (PS-NH2). We followed a tiered approach using well-developed standard operating procedures (SOPs) and sharing the same cells, serum and nanoparticles. We started with determination of the cell growth rate (tier 1), followed by a method transfer phase, in which all laboratories performed the first ILC on the MTS assay (tier 2). Based on the outcome of tier 2 and a survey of laboratory practices, specific training was organized, and the MTS assay SOP was refined. This led to largely improved intra- and inter-laboratory reproducibility in tier 3. In addition, we confirmed that PS-COOH and PS-NH2 are suitable negative and positive control nanoparticles, respectively, to evaluate impact of nanomaterials on cell viability using the MTS assay. Overall, we have demonstrated that the tiered process followed here, with the use of SOPs and representative control nanomaterials, is necessary and makes it possible to achieve good inter-laboratory reproducibility, and therefore high-quality nanotoxicological data.Web of Science108art. no. 143

Diagnostic Value of (18)F-Fluorodeoxyglucose Positron Emission Tomography Computed Tomography in Prosthetic Pulmonary Valve Infective Endocarditis

OBJECTIVES: The aim of this study was to assess the diagnostic performances of (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography (PET)/computed tomography (CT) in congenital heart disease (CHD) patients with pulmonary prosthetic valve or conduit endocarditis (PPVE) suspicion. BACKGROUND: PPVE is a major issue in the growing CHD population. Diagnosis is challenging, and usual imaging tools are not always efficient or validated in this specific population. Particularly, the diagnostic yield of (18)F-FDG PET/CT remains poorly studied in PPVE. METHODS: A retrospective multicenter study was conducted in 8 French tertiary centers. Children and adult CHD patients who underwent (18)F-FDG PET/CT in the setting of PPVE suspicion between January 2010 and May 2020 were included. The cases were initially classified as definite, possible, or rejected PPVE regarding the modified Duke criteria and finally by the Endocarditis Team consensus. The result of (18)F-FDG PET/CT had been compared with final diagnosis consensus used as gold-standard in our study. RESULTS: A total of 66 cases of PPVE suspicion involving 59 patients (median age 23 years, 73% men) were included. Sensitivity, specificity, positive predictive value, and negative predictive value of (18)F-FDG PET/CT in PPVE suspicion were respectively: 79.1% (95% CI: 68.4%-91.4%), 72.7% (95% CI: 60.4%-85.0%), 91.9% (95% CI: 79.6%-100.0%), and 47.1% (95% CI: 34.8%-59.4%). (18)F-FDG PET/CT findings would help to correctly reclassify 57% (4 of 7) of possible PPVE to definite PPVE. CONCLUSIONS: Using (18)F-FDG PET/CT improves the diagnostic accuracy of the Duke criteria in CHD patients with suspected PPVE. Its high positive predictive value could be helpful in routine to shorten diagnosis and treatment delays and improve clinical outcomes.L'Institut de Rythmologie et modélisation Cardiaqu