306 research outputs found

    Transition in a numerical model of contact line dynamics and forced dewetting

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    We investigate the transition to a Landau-Levich-Derjaguin film in forced dewetting using a quadtree adaptive solution to the Navier-Stokes equations with surface tension. We use a discretization of the capillary forces near the receding contact line that yields an equilibrium for a specified contact angle θΔ\theta_\Delta called the numerical contact angle. Despite the well-known contact line singularity, dynamic simulations can proceed without any explicit additional numerical procedure. We investigate angles from 15∘15^\circ to 110∘110^\circ and capillary numbers from 0.000850.00085 to 0.20.2 where the mesh size Δ\Delta is varied in the range of 0.00350.0035 to 0.060.06 of the capillary length lcl_c. To interpret the results, we use Cox's theory which involves a microscopic distance rmr_m and a microscopic angle θe\theta_e. In the numerical case, the equivalent of θe\theta_e is the angle θΔ\theta_\Delta and we find that Cox's theory also applies. We introduce the scaling factor or gauge function ϕ\phi so that rm=Δ/ϕr_m = \Delta/\phi and estimate this gauge function by comparing our numerics to Cox's theory. The comparison provides a direct assessment of the agreement of the numerics with Cox's theory and reveals a critical feature of the numerical treatment of contact line dynamics: agreement is poor at small angles while it is better at large angles. This scaling factor is shown to depend only on θΔ\theta_\Delta and the viscosity ratio qq. In the case of small θe\theta_e, we use the prediction by Eggers [Phys. Rev. Lett., vol. 93, pp 094502, 2004] of the critical capillary number for the Landau-Levich-Derjaguin forced dewetting transition. We generalize this prediction to large θe\theta_e and arbitrary qq and express the critical capillary number as a function of θe\theta_e and rmr_m. An analogy can be drawn between rmr_m and the numerical slip length.Comment: This version of the paper includes the corrections indicated in Ref. [1

    Rokowanie i biologia nerwiaka węchowego: rola systemu klasyfikacji stopnia złośliwości Hyamsa

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    Esthesioneuroblastoma is a sinonasal tumor with distinct clinicopathologic features, multiple facets, and a spectrum of behavior. Characterization of this disease is challenging, and clinically, several staging systems have been used with no consensus on a single scheme. Recently, the Hyams histological grading system has emerged as a promising prognostication tool that offers an added value to stage. This review addresses prognosis and biology in esthesioneuroblastoma. More specifically, we sought to present a critical appraisal on the value of each of these stratification systems, stage vs. grade, in identifying risk groups and guiding management.Nerwiak węchowy (esthesioneuroblastoma) jest nowotworem wywodzącym się z zatok obocznych nosa i jamy nosowej, o specyficznych cechach klinicznych i patologicznych oraz różnorodnym obrazie i naturalnym przebiegu. Charakterystyka nowotworu jest wybitnie niejednorodna. Dotychczas stosowano kilka systemów klasyfikacji zaawansowania klinicznego, z których żaden nie został uznany za obowiązujący. Niedawno opracowano system klasyfikacji stopnia złośliwości Hyamsa, którego zaletą jest możliwość wykorzystania go jako czynnika prognostycznego. W artykule przedstawiono rokowanie i biologię nerwiaka węchowego. Szczegółowym celem publikacji była krytyczna ocena przydatności każdego z systemów stratyfikacyjnych (oceny stopnia zaawansowania klinicznego w korelacji z klasyfikacją złośliwości nowotworu) do określenia grup ryzyka i opracowania wytycznych postępowania

    Randomized Trials of Retosiban Versus Placebo or Atosiban in Spontaneous Preterm Labor.

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    OBJECTIVE:  The aim of this study is to assess the efficacy and safety of retosiban in spontaneous preterm labor (sPTL). STUDY DESIGN:  Two multicenter, randomized, and double-blind trials compared retosiban with placebo and retosiban with atosiban in women with a singleton pregnancy and intact membranes in sPTL at 24 to 336/7 weeks' gestation. Coprimary endpoints in the placebo-controlled trial were time to delivery (TTD) or treatment failure (whichever occurred first) and neonatal composite morbidity and mortality. The primary endpoint of the atosiban comparator trial was TTD. RESULTS:  The trials were terminated early because of slow recruitment. The placebo-controlled trial enrolled 23 participants (February 2016-July 2017; 2.6% of target);the atosiban-comparator trial enrolled 97 (March 2015-August 2017; 29% of target). Baseline participant characteristics were similar between treatments. In the placebo-controlled trial, mean gestational ages at randomization were 30.8 (retosiban, n = 10) and 30.5 weeks (placebo, n = 13), and mean times to delivery/treatment failure were 18.9 days (retosiban) and 11.1 days (placebo). Two and four neonates in the retosiban and placebo groups, respectively, had ≥1 component of the neonatal composite endpoint. In the atosiban-comparator trial, mean gestational age at randomization was 31.5 weeks (for both retosiban, n = 47, and atosiban, n = 50), and adjusted mean TTDs were 32.51 days (retosiban) and 33.71 days (atosiban; p > 0.05). Adverse events were no more common with retosiban than placebo or atosiban. CONCLUSION:  Despite considerable efforts to conduct two adequate and well-controlled studies in patients with sPTL, both studies were unable to recruit effectively and consequently terminated prematurely. Key factors negatively affecting participation were patient and physician resistance to use of a placebo comparator, lack of investigator consensus on diagnostic criteria and acceptance of protocol procedures, and ethics committee decisions. Meaningful cooperation between pharmaceutical companies, regulatory authorities, and the obstetric community is essential for future development of drugs to treat sPTL

    Spectral Theory of Sparse Non-Hermitian Random Matrices

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    Sparse non-Hermitian random matrices arise in the study of disordered physical systems with asymmetric local interactions, and have applications ranging from neural networks to ecosystem dynamics. The spectral characteristics of these matrices provide crucial information on system stability and susceptibility, however, their study is greatly complicated by the twin challenges of a lack of symmetry and a sparse interaction structure. In this review we provide a concise and systematic introduction to the main tools and results in this field. We show how the spectra of sparse non-Hermitian matrices can be computed via an analogy with infinite dimensional operators obeying certain recursion relations. With reference to three illustrative examples --- adjacency matrices of regular oriented graphs, adjacency matrices of oriented Erd\H{o}s-R\'{e}nyi graphs, and adjacency matrices of weighted oriented Erd\H{o}s-R\'{e}nyi graphs --- we demonstrate the use of these methods to obtain both analytic and numerical results for the spectrum, the spectral distribution, the location of outlier eigenvalues, and the statistical properties of eigenvectors.Comment: 60 pages, 10 figure

    Polyisoprene Nanoparticles Prepared by Polymerization in Microemulsion

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    Batch polymerization of isoprene was carried out at 25∘C in a normal microemulsion stabilized with sodium dodecyl sulfate and initiated with the redox couple tert-butyl hydroperoxide/tetraethylene-pentamine. Characterization by transmission electronic microscopy showed that polyisoprene nanoparticles with number-average diameter close to 20 nm were obtained. The low molecular weights obtained, as determined by gel permeation chromatography, were probably due to chain scission as inferred from the oxidative ambient at which polymerization was carried out. Microstructure calculated from infrared spectroscopy data indicates that the obtained polyisoprene contains around 80% total 1,4 units, which is in accordance with its glass transition temperature (-60.8∘C) determined by differential scanning calorimetry

    Multimerization of Zika Virus-NS5 Causes Ciliopathy and Forces Premature Neurogenesis

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    Zika virus (ZikV) is a flavivirus that infects neural tissues, causing congenital microcephaly. ZikV has evolved multiple mechanisms to restrict proliferation and enhance cell death, although the underlying cellular events involved remain unclear. Here we show that the ZikV-NS5 protein interacts with host proteins at the base of the primary cilia in neural progenitor cells, causing an atypical non-genetic ciliopathy and premature neuron delamination. Furthermore, in human microcephalic fetal brain tissue, ZikV-NS5 persists at the base of the motile cilia in ependymal cells, which also exhibit a severe ciliopathy. Although the enzymatic activity of ZikV-NS5 appears to be dispensable, the amino acids Y25, K28, and K29 that are involved in NS5 oligomerization are essential for localization and interaction with components of the cilium base, promoting ciliopathy and premature neurogenesis. These findings lay the foundation for therapies that target ZikV-NS5 multimerization and prevent the developmental malformations associated with congenital Zika syndrome.The work in E.M.’s laboratory was supported by grants BFU2016-77498-P, BFU2016-77498-P, and La Maratò de TV3 foundation 201833-10. M.S. holds a Ramón Y Cajal fellowship (RYC2018-025379-I). J.B.-A is a recipient of a BES-2017-080050 PhD scholarship. The work in N.V.’s laboratory was supported by grants BIO2017-83906-P, Maria de Maeztu Unit of Excellence MDM-2014-0435 (MCIU), and La Maratò de TV3 foundation 201833-10. The work in N.A.’s laboratory was supported by NIH/NINDS R00NS089859 and IDDRC-NPDA (CHOP/Penn)

    Salinity tolerance loci revealed in rice using high-throughput non-invasive phenotyping

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    High-throughput phenotyping produces multiple measurements over time, which require new methods of analyses that are flexible in their quantification of plant growth and transpiration, yet are computationally economic. Here we develop such analyses and apply this to a rice population genotyped with a 700k SNP high-density array. Two rice diversity panels, indica and aus, containing a total of 553 genotypes, are phenotyped in waterlogged conditions. Using cubic smoothing splines to estimate plant growth and transpiration, we identify four time intervals that characterize the early responses of rice to salinity. Relative growth rate, transpiration rate and transpiration use efficiency (TUE) are analysed using a new association model that takes into account the interaction between treatment (control and salt) and genetic marker. This model allows the identification of previously undetected loci affecting TUE on chromosome 11, providing insights into the early responses of rice to salinity, in particular into the effects of salinity on plant growth and transpiration.Nadia Al-Tamimi, Chris Brien, Helena Oakey, Bettina Berger, Stephanie Saade, Yung Shwen Ho, Sandra M. Schmöckel, Mark Tester and Sónia Negrã

    Haptoglobin Phenotype, Preeclampsia Risk and the Efficacy of Vitamin C and E Supplementation to Prevent Preeclampsia in a Racially Diverse Population

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    Haptoglobin's (Hp) antioxidant and pro-angiogenic properties differ between the 1-1, 2-1, and 2-2 phenotypes. Hp phenotype affects cardiovascular disease risk and treatment response to antioxidant vitamins in some non-pregnant populations. We previously demonstrated that preeclampsia risk was doubled in white Hp 2-1 women, compared to Hp 1-1 women. Our objectives were to determine whether we could reproduce this finding in a larger cohort, and to determine whether Hp phenotype influences lack of efficacy of antioxidant vitamins in preventing preeclampsia and serious complications of pregnancy-associated hypertension (PAH). This is a secondary analysis of a randomized controlled trial in which 10,154 low-risk women received daily vitamin C and E, or placebo, from 9-16 weeks gestation until delivery. Hp phenotype was determined in the study prediction cohort (n = 2,393) and a case-control cohort (703 cases, 1,406 controls). The primary outcome was severe PAH, or mild or severe PAH with elevated liver enzymes, elevated serum creatinine, thrombocytopenia, eclampsia, fetal growth restriction, medically indicated preterm birth or perinatal death. Preeclampsia was a secondary outcome. Odds ratios were estimated by logistic regression. Sampling weights were used to reduce bias from an overrepresentation of women with preeclampsia or the primary outcome. There was no relationship between Hp phenotype and the primary outcome or preeclampsia in Hispanic, white/other or black women. Vitamin supplementation did not reduce the risk of the primary outcome or preeclampsia in women of any phenotype. Supplementation increased preeclampsia risk (odds ratio 3.30; 95% confidence interval 1.61-6.82, p<0.01) in Hispanic Hp 2-2 women. Hp phenotype does not influence preeclampsia risk, or identify a subset of women who may benefit from vitamin C and E supplementation to prevent preeclampsia
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