Phase separation in a chaotic flow

The phase separation between two immiscible liquids advected by a bidimensional velocity field is investigated numerically by solving the corresponding Cahn-Hilliard equation. We study how the spinodal decomposition process depends on the presence -or absence- of Lagrangian chaos. A fully chaotic flow, in particular, limits the growth of domains and for unequal volume fractions of the liquids, a characteristic exponential distribution of droplet sizes is obtained. The limiting domain size results from a balance between chaotic mixing and spinodal decomposition, measured in terms of Lyapunov exponent and diffusivity constant, respectively.Comment: Minor changes - Version accepted for publication - Physical Review Letter

Umbilical endometriosis

We report two women who presented with a recurrent, mildly painful, bluish nodule in the umbilicus. Both patients complained of local tenderness and occasional bleeding that increased during menstruation. Neither patient had had previous pelvic surgery. Excision of the lesions revealed a primary umbilical endometriosis; in one case, a simultaneous laparoscopy showed a pelvic endometriosis. We review the current literature and discuss the possible etiopathogenesis and when a laparoscopy is indicated to diagnose a concomitant pelvic endometriosis. Umbilical endometriosis is a very rare disease but should be considered in the differential diagnosis of umbilical lesion

Self-Diffusion of a Polymer Chain in a Melt

Self-diffusion of a polymer chain in a melt is studied by Monte Carlo simulations of the bond fluctuation model, where only the excluded volume interaction is taken into account. Polymer chains, each of which consists of $N$ segments, are located on an $L \times L \times L$ simple cubic lattice under periodic boundary conditions, where each segment occupies $2 \times 2 \times 2$ unit cells. The results for $N=32, 48, 64, 96, 128, 192, 256, 384$ and 512 at the volume fraction $\phi \simeq 0.5$ are reported, where $L = 128$ for $N \leq 256$ and L=192 for $N \geq 384$. The $N$-dependence of the self-diffusion constant $D$ is examined. Here, $D$ is estimated from the mean square displacements of the center of mass of a single polymer chain at the times larger than the longest relaxation time. From the data for $N = 256$, 384 and 512, the apparent exponent $x_{\rm d}$, which describes the apparent power law dependence of $D$ on $N$ as $D \propto N^{- x_{\rm d}}$, is estimated as $x_{\rm d} \simeq 2.4$. The ratio $D \tau /$ seems to be a constant for $N = 192, 256, 384$ and 512, where $\tau$ and $$ denote the longest relaxation time and the mean square end-to-end distance, respectively.Comment: 4 pages, 3 figures, submitted to J. Phys. Soc. Jp

Host Cell Phosphatidylcholine Is a Key Mediator of Malaria Parasite Survival during Liver Stage Infection

During invasion, Plasmodium, the causative agent of malaria, wraps itself in a parasitophorous vacuole membrane (PVM), which constitutes a critical interface between the parasite and its host cell. Within hepatocytes, each Plasmodium sporozoite generates thousands of new parasites, creating high demand for lipids to support this replication and enlarge the PVM. Here, a global analysis of the total lipid repertoire of Plasmodium-infected hepatocytes reveals an enrichment of neutral lipids and the major membrane phospholipid, phosphatidylcholine (PC). While infection is unaffected in mice deficient in key enzymes involved in neutral lipid synthesis and lipolysis, ablation of rate-limiting enzymes in hepatic PC biosynthetic pathways significantly decreases parasite numbers. Host PC is taken up by both P. berghei and P. falciparum and is necessary for correct localization of parasite proteins to the PVM, which is essential for parasite survival. Thus, Plasmodium relies on the abundance of these lipids within hepatocytes to support infection.Seventh Framework Programme (European Commission) (Grant Agreement 311502)Fundacao para a Ciencia e a Tecnologia (Grant EXCL/IMI-MIC/0056/2012)Fundacao para a Ciencia e a Tecnologia (Grant PTDC/IMI-MIC/1568/2012

Aeolian Remobilisation of Volcanic Ash: Outcomes of a Workshop in the Argentinian Patagonia

During explosive volcanic eruptions, large quantities of tephra can be dispersed and deposited over wide areas. Following deposition, subsequent aeolian remobilisation of ash can potentially exacerbate primary impacts on timescales of months to millennia. Recent ash remobilisation events (e.g., following eruptions of Cordón Caulle 2011; Chile, and Eyjafjallajökull 2010, Iceland) have highlighted this to be a recurring phenomenon with consequences for human health, economic sectors, and critical infrastructure. Consequently, scientists from observatories and Volcanic Ash Advisory Centers (VAACs), as well as researchers from fields including volcanology, aeolian processes and soil sciences, convened at the San Carlos de Bariloche headquarters of the Argentinian National Institute of Agricultural Technology to discuss the ?state of the art? for field studies of remobilised deposits as well as monitoring, modeling and understanding ash remobilisation. In this article, we identify practices for field characterisation of deposits and active processes, including mapping, particle characterisation and sediment traps. Furthermore, since forecast models currently rely on poorly-constrained dust emission schemes, we call for laboratory and field measurements to better parameterise the flux of volcanic ash as a function of friction velocity. While source area location and extent are currently the primary inputs for dispersion models, once emission schemes become more sophisticated and better constrained, other parameters will also become important (e.g., source material volume and properties, effective precipitation, type and distribution of vegetation cover, friction velocity). Thus, aeolian ash remobilisation hazard and associated impact assessment require systematic monitoring, including the development of a regularly-updated spatial database of resuspension source areas.Fil: Jarvis, Paul A.. Universidad de Ginebra. Facultad de Ciencias. Sección de Ciencias de la Tierra; SuizaFil: Bonadonna, Costanza. Universidad de Ginebra. Facultad de Ciencias. Sección de Ciencias de la Tierra; SuizaFil: Dominguez, Lucia. Universidad de Ginebra. Facultad de Ciencias. Sección de Ciencias de la Tierra; SuizaFil: Forte, Pablo Brian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Frischknecht, Corine. Universidad de Ginebra. Facultad de Ciencias. Sección de Ciencias de la Tierra; SuizaFil: Bran, Donaldo. Instituto Nacional de Tecnología Agropecuaria; ArgentinaFil: Aguilar, Rigoberto. No especifíca;Fil: Beckett, Frances. No especifíca;Fil: Elissondo, Manuela. Secretaría de Industria y Minería. Servicio Geológico Minero Argentino; ArgentinaFil: Gillies, John. Desert Research Institute; Estados UnidosFil: Kueppers, Ulrich. Ludwig Maximilians Universitat; AlemaniaFil: Merrison, Jonathan. University Aarhus. Institut for Fysik Og Astronomi; DinamarcaFil: Varley, Nick. Universidad de Colima; MéxicoFil: Wallace, Kristi L.. United States Geological Survey; Estados Unido

Evolution and Nucleosynthesis of Very Massive Stars

In this chapter, after a brief introduction and overview of stellar evolution, we discuss the evolution and nucleosynthesis of very massive stars (VMS: M>100 solar masses) in the context of recent stellar evolution model calculations. This chapter covers the following aspects: general properties, evolution of surface properties, late central evolution, and nucleosynthesis including their dependence on metallicity, mass loss and rotation. Since very massive stars have very large convective cores during the main-sequence phase, their evolution is not so much affected by rotational mixing, but more by mass loss through stellar winds. Their evolution is never far from a homogeneous evolution even without rotational mixing. All VMS at metallicities close to solar end their life as WC(-WO) type Wolf-Rayet stars. Due to very important mass loss through stellar winds, these stars may have luminosities during the advanced phases of their evolution similar to stars with initial masses between 60 and 120 solar masses. A distinctive feature which may be used to disentangle Wolf-Rayet stars originating from VMS from those originating from lower initial masses is the enhanced abundances of neon and magnesium at the surface of WC stars. At solar metallicity, mass loss is so strong that even if a star is born with several hundred solar masses, it will end its life with less than 50 solar masses (using current mass loss prescriptions). At the metallicity of the LMC and lower, on the other hand, mass loss is weaker and might enable star to undergo pair-instability supernovae.Comment: 42 pages, 20 figures, Book Chapter in "Very Massive Stars in the Local Universe", Springer, Ed. Jorick S. Vin

A Gamma-Herpesvirus Glycoprotein Complex Manipulates Actin to Promote Viral Spread

Viruses lack self-propulsion. To move in multi-cellular hosts they must therefore manipulate infected cells. Herpesviruses provide an archetype for many aspects of host manipulation, but only for alpha-herpesviruses in is there much information about they move. Other herpesviruses are not necessarily the same. Here we show that Murine gamma-herpesvirus-68 (MHV-68) induces the outgrowth of long, branched plasma membrane fronds to create an intercellular network for virion traffic. The fronds were actin-based and RhoA-dependent. Time-lapse imaging showed that the infected cell surface became highly motile and that virions moved on the fronds. This plasma membrane remodelling was driven by the cytoplasmic tail of gp48, a MHV-68 glycoprotein previously implicated in intercellular viral spread. The MHV-68 ORF58 was also required, but its role was simply transporting gp48 to the plasma membrane, since a gp48 mutant exported without ORF58 did not require ORF58 to form membrane fronds either. Together, gp48/ORF58 were sufficient to induce fronds in transfected cells, as were the homologous BDLF2/BMRF2 of Epstein-Barr virus. Gp48/ORF58 therefore represents a conserved module by which gamma-herpesviruses rearrange cellular actin to increase intercellular contacts and thereby promote their spread

Induced pseudoscalar coupling of the proton weak interaction

The induced pseudoscalar coupling $g_p$ is the least well known of the weak coupling constants of the proton's charged--current interaction. Its size is dictated by chiral symmetry arguments, and its measurement represents an important test of quantum chromodynamics at low energies. During the past decade a large body of new data relevant to the coupling $g_p$ has been accumulated. This data includes measurements of radiative and non radiative muon capture on targets ranging from hydrogen and few--nucleon systems to complex nuclei. Herein the authors review the theoretical underpinnings of $g_p$, the experimental studies of $g_p$, and the procedures and uncertainties in extracting the coupling from data. Current puzzles are highlighted and future opportunities are discussed.Comment: 58 pages, Latex, Revtex4, prepared for Reviews of Modern Physic

Existing benchmark systems for assessing global warming potential of buildings – Analysis of IEA EBC Annex 72 cases

Life cycle assessment (LCA) is increasingly being used as a tool by the building industry and actors to assess the global warming potential (GWP) of building activities. In several countries, life cycle based requirements on GWP are currently being incorporated into building regulations. After the establishment of general calculation rules for building LCA, a crucial next step is to evaluate the performance of the specific building design. For this, reference values or benchmarks are needed, but there are several approaches to defining these. This study presents an overview of existing benchmark systems documented in seventeen cases from the IEA EBC Annex 72 project on LCA of buildings. The study characterizes their different types of methodological background and displays the reported values. Full life cycle target values for residential and non-residential buildings are found around 10-20 kg CO$_2$e/m$^2$/y, whereas reference values are found between 20-80 kg CO$_2$e/m$^2$/y. Possible embodied target- and reference values are found between 1-12 kg CO$_2$e/m$^2$/y for both residential and non-residential buildings. Benchmark stakeholders can use the insights from this study to understand the justifications of the background methodological choices and to gain an overview of the level of GWP performance across benchmark systems