Bulk and interfacial stresses in suspensions of soft and hard colloids

We explore the influence of particle softness and internal structure on both the bulk and interfacial rheological properties of colloidal suspensions. We probe bulk stresses by conventional rheology, by measuring the flow curves, shear stress vs strain rate, for suspensions of soft, deformable microgel particles and suspensions of near hard-sphere-like silica particles. A similar behavior is seen for both kind of particles in suspensions at concentrations up to the random close packing volume fraction, in agreement with recent theoretical predictions for sub-micron colloids. Transient interfacial stresses are measured by analyzing the patterns formed by the interface between the suspensions and their own solvent, due to a generalized Saffman-Taylor hydrodynamic instability. At odd with the bulk behavior, we find that microgels and hard particle suspensions exhibit vastly different interfacial stress properties. We propose that this surprising behavior results mainly from the difference in particle internal structure (polymeric network for microgels vs compact solid for the silica particles), rather than softness alone.Comment: 20 pages, 8 figure

Hamiltonian structure of thermodynamics with gauge

The state of a thermodynamic system being characterized by its set of extensive variables $q^{i}(i=1,...,n) ,$ we write the associated intensive variables $\gamma_{i},$ the partial derivatives of the entropy $S(q^{1},...,q^{n}) \equiv q_{0},$ in the form $\gamma_{i}=-p_{i}/p_{0}$ where $p_{0}$ behaves as a gauge factor. When regarded as independent, the variables $q^{i},p_{i}(i=0,...,n)$ define a space $\mathbb{T}$ having a canonical symplectic structure where they appear as conjugate. A thermodynamic system is represented by a $n+1$-dimensional gauge-invariant Lagrangian submanifold $\mathbb{M}$ of $\mathbb{T}.$ Any thermodynamic process, even dissipative, taking place on $\mathbb{M}$ is represented by a Hamiltonian trajectory in $\mathbb{T},$ governed by a Hamiltonian function which is zero on $\mathbb{M}.$ A mapping between the equations of state of different systems is likewise represented by a canonical transformation in $\mathbb{T}.$ Moreover a natural Riemannian metric exists for any physical system, with the $q^{i}$'s as contravariant variables, the $p_{i}$'s as covariant ones. Illustrative examples are given.Comment: Proofs corrections latex vali.tex, 1 file, 28 pages [SPhT-T00/099], submitted to Eur. Phys. J.

A Near-half-century Simulation of the Solar Corona

We present an overview of results from a magnetofrictional model of the entire solar corona over a period of 47 yr. The simulation self-consistently reproduces decades of solar phenomena, varying in duration between rapid eruptions and the long-term solar cycles, from an input of observed active regions emerging at the photosphere. We have developed a geometric approach to use magnetic helicity to identify and localize the frequent eruptions that occur in the simulation. This method allows us to match our results to extreme-ultraviolet observations of transient events. We have analyzed the evolving magnetic topology by computing the squashing factor and segmenting the corona into discrete magnetic domains bounded by the Separatrix-Web. The simulations show a more dynamic structure to the Separatrix-Web than is predicted by potential field models, which may explain solar wind observations

Prevalence and characteristics of methicillin-resistant coagulase-negative staphylococci from livestock, chicken carcasses, bulk tank milk, minced meat, and contact persons

BACKGROUND: Methicillin-resistant coagulase-negative staphylococci (MR-CNS) are of increasing importance to animal and public health. In veterinary medicine and along the meat and milk production line, only limited data were so far available on MR-CNS characteristics. The aim of the present study was to evaluate the prevalence of MR-CNS, to identify the detected staphylococci to species level, and to assess the antibiotic resistance profiles of isolated MR-CNS strains. RESULTS: After two-step enrichment and growth on chromogenic agar, MR-CNS were detected in 48.2% of samples from livestock and chicken carcasses, 46.4% of samples from bulk tank milk and minced meat, and 49.3% of human samples. Using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS), 414 selected MR-CNS strains belonged to seven different species (S. sciuri, 32.6%; S. fleurettii, 25.1%; S. haemolyticus, 17.4%; S. epidermidis, 14.5%, S. lentus, 9.2%; S. warneri, 0.7%; S. cohnii, 0.5%). S. sciuri and S. fleurettii thereby predominated in livestock, BTM and minced meat samples, whereas S. epidermidis and S. haemolyticus predominated in human samples. In addition to beta-lactam resistance, 33-49% of all 414 strains were resistant to certain non-beta-lactam antibiotics (ciproflaxacin, clindamycin, erythromycin, tetracycline). CONCLUSIONS: A high prevalence of MR-CNS was found in livestock production. This is of concern in view of potential spread of mecA to S. aureus (MRSA). Multiresistant CNS strains might become an emerging problem for veterinary medicine. For species identification of MR-CNS isolated from different origins, MALDI-TOF MS proved to be a fast and reliable tool and is suitable for screening of large sample amounts

Le sentiment de compétence professionnelle chez les physiothérapeutes diplômé(e)s en Suisse lors de leurs deux premières années d’activité – une enquête par questionnaire

Evaluer le sentiment de compétence professionnelle des physiothérapeutes diplômé(e)s en Suisse lors de leurs deux premières années d’activité et identifier les forces et les faiblesses de leurs modèles de formation

Comportement D’une Variété Précoce De Mil (Pennisetum glaucum (L.) R. Br) En Réponse A Différents Types De Fumures Combinées A Une Sécheresse De Fin De Cycle Au Nord De La Côte d'Ivoire

Cet article analyse l’influence de l’utilisation des fumures organiques et minérales sur la productivité du mil (Pennisetum glaucum (L.) R. Br) face à la baisse de la fertilité des sols dans un contexte de changements climatiques au Nord de la Côte d’Ivoire. Une étude a été menée pour analyser le comportement d’une variété précoce de mil en fonction de trois fumures organiques et une fumure minérale en situation de déficit hydrique post-floral. Le dispositif utilisé a été un bloc de Fisher complètement randomisé comportant quatre répétitions et cinq traitements (T1: témoin, T2: fiente de volaille, T3: déjection de lapin, T4: déjection de boeuf, T5: fumure minérale N-P-K-S-B+Urée). Les observations et mesures ont porté sur les stades de développement et les paramètres de croissance des plants. L’évapotranspiration réelle de la culture, le taux de satisfaction des besoins en eau des plants, le rendement et ses composantes ont été calculés ainsi que l’efficacité des fumures utilisées. Les résultats ont montré un déficit hydrique au cours de la phase reproductive. La variété de mil étudiée a présenté un cycle de développement plus court, une meilleure croissance, des valeurs de composantes du rendement élevées avec l’application de la fiente de volaille. La fumure fiente de volaille a été donc plus efficace que les autres fumures malgré la poche de sécheresse observée en fin de cycle. L’apport de la fiente de volaille peut être recommandé pour les cultures qui ont besoin de fertilisants, comme les variétés précoces de mil, car elle raccourcit la durée du cycle de culture permettant ainsi aux plants d’échapper aux conséquences néfastes du déficit hydrique de fin de cycle. This Article Analyzes The Influence Of Organic And MineralManures On Millet (Pennisetum Glaucum (L.) R. Br.) Productivity In The Context Of Climate Change And Soil Fertility Degradation In Northern Côte d'Ivoire. To Do This, A Study Was Conducted To Analyze The Response Of An Early VarietyOfMillet Based On Three OrganicManures And OneMineralManure In Post-Floral Water Deficit Situations. The Experiment Had A Completely Randomized Block In Four Repetitions And Five Treatments (T1: Control, T2: Chicken Dropping; T3: Rabbit Dropping, T4: Cow Dung; T5: N-P-K-S B+Urea Mineral Fertilizer). Observations And Measurements Focused On The Stages Of Development And Plant Growth Parameters. The Crop Evapotranspiration, The Satisfaction Rate Of Plant's Water Needs, Yield And ComponentsWere Calculated, And The Efficiency Of The Manure Used. The Results Showed A Water Deficit During The Reproductive Phase. The Millet Presented A Shorter Development Cycle, Better Growth And High Yield Component Values With Chicken Dropping Treatment. The Chicken Dropping Was More Effective Than Other Manure, Despite The Drought Observed At The End Of Crop Cycle. Applying Chicken Dropping May Be Recommended For Crops Needs Immediate Fertilizers, Such As Early Millet Varieties, Because It Shortens The Duration Of The Growing Cycle, Thus Allowing Plants To Escape The Harmful Consequences Of The End Of Crop Cycle Water Deficit

Towards an adaptive landscape for short-necked plesiosaurians

Plesiosauria is the most diverse and probably the most disparate clade of secondarily aquatic tetrapods. The frequency and intensity of morphological convergences within this group and the strong constrains of the aquatic medium make Plesiosauria an ideal model for testing the processes of morphological diversification. The adaptive landscape of ple- siosaurians has been summarised to two global morphotypes: one for short-necked forms (pliosauromorphs) and one for long-necked forms (plesiosauromorphs). Although these were historically conceived as long-liven, monophylogenetic clade, it is increasingly clear that these body plans each arose multiple times independently during the evolutionary history of Plesiosauria, providing evidence of a macroevolutionary adaptive landscape. We investi- gate the morphological diversification of the two major groups of short-necked plesiosauri- ans: Pliosauridae and Polycotylidae. Using an updated phylogenetic dataset incorporating most plesiosaurians and a morphological dataset summarising the Bauplan and diet-related features, we investigate the rates of evolution, patterns of morphospace occupation, and disparity over time of these two clades. Our results show that a handful of clearly distinct craniodental architectures exist within pliosaurids and polcotylids and that several episodes of convergent evolution affected these clades. This indicates that while there is probably no such thing as single ‘pliosauromorph’ morphotype, the craniodental adaptive landscape of these animals might be quite simple, with a few optimal morphologies

New VVV Survey Globular Cluster Candidates in the Milky Way Bulge

© 2017 The American Astronomical Society. All rights reserved.It is likely that a number of Galactic globular clusters remain to be discovered, especially toward the Galactic bulge. High stellar density combined with high and differential interstellar reddening are the two major problems for finding globular clusters located toward the bulge. We use the deep near-IR photometry of the VISTA Variables in the Vía Láctea (VVV) Survey to search for globular clusters projected toward the Galactic bulge, and hereby report the discovery of 22 new candidate globular clusters. These objects, detected as high density regions in our maps of bulge red giants, are confirmed as globular cluster candidates by their color-magnitude diagrams. We provide their coordinates as well as their near-IR color-magnitude diagrams, from which some basic parameters are derived, such as reddenings and heliocentric distances. The color-magnitude diagrams reveal well defined red giant branches in all cases, often including a prominent red clump. The new globular cluster candidates exhibit a variety of extinctions (0.06 < A Ks < 2.77) and distances (5.3 < D < 9.5 kpc). We also classify the globular cluster candidates into 10 metal-poor and 12 metal-rich clusters, based on the comparison of their color-magnitude diagrams with those of known globular clusters also observed by the VVV Survey. Finally, we argue that the census for Galactic globular clusters still remains incomplete, and that many more candidate globular clusters (particularly the low luminosity ones) await to be found and studied in detail in the central regions of the Milky Way.Peer reviewedFinal Accepted Versio