227 research outputs found
Symmetric Periodic Solutions of the Anisotropic Manev Problem
We consider the Manev Potential in an anisotropic space, i.e., such that the
force acts differently in each direction. Using a generalization of the
Poincare' continuation method we study the existence of periodic solutions
for weak anisotropy. In particular we find that the symmetric periodic orbits
of the Manev system are perturbed to periodic orbits in the anisotropic
problem.Comment: Late
Sialoendoscopia: una nueva alternativa en el tratamiento de la patologĂa salival. Nuestra experiencia
Objectives: Sialoendoscopy is a procedure used to visualize
the salivary ducts and their pathology. It can be used either
as a diagnostic method to rule out inflammatory processes
in the parotid and submandibular glands (diagnostic
sialoendoscopy) or to treat pathological areas (stenosis,
extract foreign bodies or sialolithiasis) through the use of appropriate
instruments (interventionist sialoendoscopy). We
attempt to prove a declining rate of salivary gland excision.
Patients and method: Sialoendoscopy was performed in
8 patients.
Results: Of these, 50 % of patients were diagnosed as having
sialolithiasis and the other 50 % had chronic sialoadenitis. In
patients with sialolithiasis, sialoendoscopy allowed the
extraction of the calculus in two patients (50 %). In the remainder,
sialoendoscopy provided confirmation of the
diagnosis in all cases.
Conclusions: Sialoendoscopy is a new technique for use in
the diagnosis, treatment and post-operative management
of sialolithiasis, sialoadenitis and other salivary gland
pathologies
Cooling history and emplacement of a pyroxenitic lava as proxy for understanding Martian lava flows
Terrestrial analogues are often investigated to get insights into the geological processes occurring on other planetary bodies. Due to its thickness and petrological similarities, the pyroxenitic layer of the 120m-thick magmatic pile Theo’s Flow (Archean Abitibi greenstone belt Ontario, Canada), has always been regarded as the terrestrial analogue for Martian nakhlites. However, its origin and cooling history and, as a consequence those of nakhlites, have always been a matter of vigorous debate. Did this lava flow originate from a single magmatic event similar to those supposed to occur on Mars or do the different units derive from multiple eruptions? We demonstrate, by a combination of geothermometric constraints on augite single crystals and numerical simulations, that Theo’s Flow has been formed by multiple magma emplacements that occurred at different times. This discovery supports the idea that the enormous lava flows with similar compositions observed on Mars could be the result of a process where low viscosity lavas are emplaced during multiple eruptions. This has profound implications for understanding the multiscale mechanisms of lava flow emplacement on Earth and other planetary bodies
In Vitro Modeling of Tumor-Immune System Interaction.
Immunotherapy has emerged during the past two decades as an innovative and successful form of cancer treatment. However, frequently, mechanisms of actions are still unclear, predictive markers are insufficiently characterized, and preclinical assays for innovative treatments are poorly reliable. In this context, the analysis of tumor/immune system interaction plays key roles, but may be unreliably mirrored by in vivo experimental models and standard bidimensional culture systems. Tridimensional cultures of tumor cells have been developed to bridge the gap between in vitro and in vivo systems. Interestingly, defined aspects of the interaction of cells from adaptive and innate immune systems and tumor cells may also be mirrored by 3D cultures. Here we review in vitro models of cancer/immune cell interaction and we propose that updated technologies might help develop innovative treatments, identify biologicals of potential clinical relevance, and select patients eligible for immunotherapy treatments
Pest Management in Grain Legumes: Potential and Limitations
Grain legumes such as chickpea, pigeonpea, cowpea, field pea , lentil, ,
and Phaseolus beans are the principal source of dietary protein among vegetarians,
and are an integral part of daily diet in several forms worldwide. They are an
important component of cropping systems to maintain soil fertility because of
their ability to fix atmospheric nitrogen, extract water and nutrients from the
deeper layers of the soil as compared to cereals, and add organic matter into the
soil through leaf drop. However, grain legumes are mainly grown under rainfed
conditions and the productivity levels are quite low mainly because of severe
losses due to insect pests and diseases. Average grain yield of pulses (0.86 t/
ha) is only about onefourth
the average yields of cereals (3.54 t/ha). Production
and productivity of grain legumes is constrained by several biotic and abiotic
factors, and suffer an average of 31.9 to 69.6% loss in crop productivity due to
insects, diseases, drought, weeds, and soil fertility. Pod borers (Helicoverpa
and Maruca), Fusarium wilts, viral diseases, Ascochyta blight and Botrytis gray
mold (Chen et al., 2011)..
Relative Equilibria in the Four-Vortex Problem with Two Pairs of Equal Vorticities
We examine in detail the relative equilibria in the four-vortex problem where
two pairs of vortices have equal strength, that is, \Gamma_1 = \Gamma_2 = 1 and
\Gamma_3 = \Gamma_4 = m where m is a nonzero real parameter. One main result is
that for m > 0, the convex configurations all contain a line of symmetry,
forming a rhombus or an isosceles trapezoid. The rhombus solutions exist for
all m but the isosceles trapezoid case exists only when m is positive. In fact,
there exist asymmetric convex configurations when m < 0. In contrast to the
Newtonian four-body problem with two equal pairs of masses, where the symmetry
of all convex central configurations is unproven, the equations in the vortex
case are easier to handle, allowing for a complete classification of all
solutions. Precise counts on the number and type of solutions (equivalence
classes) for different values of m, as well as a description of some of the
bifurcations that occur, are provided. Our techniques involve a combination of
analysis and modern and computational algebraic geometry
Subsea Compression Applications - Panel Session
TutorialThe use of Subsea gas compression technology for subsea re-injection and/or gas transport boosting represents a new and exciting application for rotating equipment, which will allow new gas/condensate field production opportunities, enhanced recovery of existing gas/condensate fields and cost effective production from marginal gas fields. This panel session includes short presentations on the benefits of subsea compression, an overview of currently ongoing projects, and recent advances and technologies that are available and/or under development for subsea gas compression. The panel session includes presentations from Shell Global Solutions, Aker Solutions, MAN DIESEL & TURBO, GE OIL & GAS and DRESSER-RAND. The respective presentation titles are: Subsea Processing - Multiphase Boosting and Compression – Shell Global Solutions; Subsea Compression; Present Status and Experience – Aker Solutions; HOFIMTM Type Compressors for Subsea Applications; MAN Diesel & Turbo; GE Oil & Gas Experience in Subsea Gas Compression Technology Development – GE Oil & Gas; DATUM I Compressor for Subsea Applications: Update on Qualification Efforts- Dresser-Rand
Noncanonical sortase-mediated assembly of pilus type 2b in group B Streptococcus
Group B Streptococcus (GBS) expresses 3 structurally distinct pilus types (1, 2a, and 2b) identified as important virulence factors and vaccine targets. These pili are heterotrimeric polymers, covalently assembled on the cell wall by sortase (Srt) enzymes. We investigated the pilus-2b biogenesis mechanism by using a multidisciplinary approach integrating genetic, biochemical, and structural studies to dissect the role of the 2 pilus-2b-associated Srts. We show that only 1 sortase (SrtC1-2b) is responsible for pilus protein polymerization, whereas the second one (Srt2-2b) does not act as a pilin polymerase, but similarly to the housekeeping class A Srt (SrtA), it is involved in cell-wall pilus anchoring by targeting the minor ancillary subunit. Based on its function and sequence features, Srt2-2b does not belong to class C Srts (SrtCs), nor is it a canonical member of any other known family of Srts. We also report the crystal structure of SrtC1-2b at 1.9 Ă… resolution. The overall fold resembles the typical structure of SrtCs except for the N-terminal lid region that appears in an open conformation displaced from the active site. Our findings reveal that GBS pilus type 2b biogenesis differs significantly from the current model of pilus assembly in gram-positive pathogens.-Lazzarin, M., Cozzi, R., Malito, E., Martinelli, M., D'Onofrio, M., Maione, D., Margarit, I., and Rinaudo, C. D. Noncanonical sortase-mediated assembly of pilus type 2b in group B Streptococcus
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