Vortex formation for a non-local interaction model with Newtonian repulsion and superlinear mobility

We consider density solutions for gradient flow equations of the form $u_t = \nabla \cdot ( \gamma(u) \nabla \mathrm N(u))$, where $\mathrm N$ is the Newtonian repulsive potential in the whole space $\mathbb R^d$ with the nonlinear convex mobility $\gamma(u)=u^\alpha$, and $\alpha>1$. We show that solutions corresponding to compactly supported initial data remain compactly supported for all times leading to moving free boundaries as in the linear mobility case $\gamma(u)=u$. For linear mobility it was shown that there is a special solution in the form of a disk vortex of constant intensity in space $u=c_1t^{-1}$ supported in a ball that spreads in time like $c_2t^{1/d}$, thus showing a discontinuous leading front or shock. Our present results are in sharp contrast with the case of concave mobilities of the form $\gamma(u)=u^\alpha$, with $0<\alpha<1$ studied in [9]. There, we developed a well-posedness theory of viscosity solutions that are positive everywhere and moreover display a fat tail at infinity. Here, we also develop a well-posedness theory of viscosity solutions that in the radial case leads to a very detail analysis allowing us to show a waiting time phenomena. This is a typical behavior for nonlinear degenerate diffusion equations such as the porous medium equation. We will also construct explicit self-similar solutions exhibiting similar vortex-like behaviour characterizing the long time asymptotics of general radial solutions under certain assumptions. Convergent numerical schemes based on the viscosity solution theory are proposed analysing their rate of convergence. We complement our analytical results with numerical simulations ilustrating the proven results and showcasing some open problems

Light-induced iodoperfluoroalkylation reactions of carbon-carbon multiple bonds in water

In this work we have undertaken the radical-induced addition of 1-iodo-n-perfluorobutane onto electron-rich alkenes, alkenes with electron withdrawing groups, and alkynes in water, initiated photochemically. The lack of hydrogen donor (i.e.: (Me 3Si) 3SiH) in our reaction medium facilitates a Halogen Atom-transfer reaction (HAT), affording the respective perfluorobutylated alkyl and alkenyl halides (iodides) in good yields in water. We have also found that water exerts a relevant solvent effect on the rates of perfluoroalkyl radical additions onto double and triple bonds. The stereoselectivity of the radical addition reaction of alkynes is studied. The novelty of this work relies on the photochemical generation of fluorinated radicals in water, and the Halogen Atom-transfer addition reactions of iodoperfluoroalkanes onto carbon-carbon unsaturated bonds in water induced by light.Fil: Slodowicz, Mariel Pamela. Universidad de Belgrano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Barata Vallejo, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Vázquez, A.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Sbarbati Nudelman, N.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Química Orgánica; ArgentinaFil: Postigo, Jose Alberto. Universidad de Belgrano; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Comportamiento mecánico de mezclas de escoria vítrea de horno alto y metacaolín activadas alcalinamente: estudio estadístico = Mechanical behaviour of alkali-activated metakaolin blended pastes: statistical study

El estudio y desarrollo de cementos alternativos y más eco-eficientes que el cemento Portland es un tema de gran impacto a nivel científico y tecnológico. Entre esos posibles cementos se encuentran los cementos alcalinos que son materiales conglomerantes obtenidos por la interacción química de materiales silico-aluminosos cálci- cos y disoluciones fuertemente alcalinas. En el presente trabajo se estudia el comportamiento mecánico y la com- posición mineralógica de mezclas de escoria vítrea de horno alto y metacaolín activadas alcalinamente con disoluciones de NaOH. El objetivo de este estudio es conocer cómo afectan parámetros tales como la relación escoria/metacaolín, la concentración de la disolución activadora y la temperatura de curado, al desarrollo re- sistente de las mezclas. A través del estudio estadístico realizado se ha podido establecer la influencia de cada variable y modelizar el comportamiento resistente de estos cementos alcalinos. Se concluye que la concentra- ción del activador y la relación escoria/metacaolín son los parámetros más relevantes

Electronic and Geometric Corrugation of Periodically Rippled, Self-nanostructured Graphene Epitaxially Grown on Ru(0001)

Graphene epitaxially grown on Ru(0001) displays a remarkably ordered pattern of hills and valleys in Scanning Tunneling Microscopy (STM) images. To which extent the observed "ripples" are structural or electronic in origin have been much disputed recently. A combination of ultrahigh resolution STM images and Helium Atom diffraction data shows that i) the graphene lattice is rotated with respect to the lattice of Ru and ii) the structural corrugation as determined from He diffraction is substantially smaller (0.015 nm) than predicted (0.15 nm) or reported from X-Ray Diffraction or Low Energy Electron Diffraction. The electronic corrugation, on the contrary, is strong enough to invert the contrast between hills and valleys above +2.6 V as new, spatially localized electronic states enter the energy window of the STM. The large electronic corrugation results in a nanostructured periodic landscape of electron and holes pockets.Comment: 16 pages, 6 figure

Fundamentals of Fluid Film Journal Bearing Operation and Modeling

TutorialTutorial 14: Widely used in turbomachinery, the fluid film journal bearing is critical to a machine’s overall reliability level. Their design complexity and application severity continue to increase making it challenging for the plant machinery engineer to evaluate their reliability. This tutorial provides practical knowledge on their basic operation and what physical effects should be included in modeling a bearing to help ensure its reliable operation in the field. All the important theoretical aspects of journal bearing modeling, such as film pressure, film and pad temperatures, thermal and mechanical deformations and turbulent flow are reviewed. Through some examples, the tutorial explores how different effects influence key performance characteristics like minimum film thickness, Babbitt temperature as well as stiffness and damping coefficients. Due to their increasing popularity, the operation and analysis of advanced designs using directed lubrication principles, such as inlet grooves and associated starvation issues, are also examined with several examples including comparisons to manufacturers’ test data

Suppression Subtractive Hybridization PCR Isolation of cDNAs from a Caribbean Soft Coral

Transcriptomic studies of marine organisms are still in their infancy. A partial, subtracted expressed sequence tag (EST) library of the Caribbean octocoral Erythropodium caribaeorum and the sea fan Gorgonia ventalina has been analyzed in order to find novel genes or differences in gene expression related to potential secondary metabolite production or symbioses. This approach entails enrichment for potential non- housekeeping genes using the suppression subtractive hybridization (SSH) polymerase chain reaction (PCR) method. More than 500 expressed sequence tags (ESTs) were generated after cloning SSH products, which yielded at least 53 orthologous groups of proteins (COGs) and Pfam clusters, including transcription factors (Drosophila Big Brother), catalases, reverse transcriptases, ferritins and various hypothetical protein sequences. A total of 591 EST sequences were deposited into GenBank [dbEST: FL512138 - FL512331, and GH611838]. The results represent proof of concept for enrichment of unique transcripts over housekeeping genes, such as actin or ribosomal genes, which comprised approximately 17% of the total dataset. Due to the gene and sequence diversity of some ESTs, such sequences can find utility as molecular markers in current and future studies of this species and other soft coral biogeography, chemical ecology, phylogenetics, and evolution

CCR5Δ32 variant and cardiovascular disease in patients with rheumatoid arthritis: a cohort study

Introduction The aim of our study was to analyze the influence of the CCR5Δ32 polymorphism in the risk of cardiovascular (CV) events and subclinical atherosclerosis among patients with rheumatoid arthritis (RA). Methods A total of 645 patients fulfilling the American Rheumatism Association 1987 revised classification criteria for RA were studied. Patients were genotyped for the CCR5 rs333 polymorphism using predesigned TaqMan assays. Also, HLA DRB1 genotyping was performed using molecular-based methods. Carotid intima-media thickness, flow-mediated endothelium-dependent dilatation (FMD) and endothelium-independent vasodilatation, which were used as surrogate markers of subclinical atherosclerosis, were measured in a subgroup of patients with no clinical CV disease. Results A lower frequency of carriers of the CCR5Δ32 allele among patients with CV events (3.4% versus 11.3%, P = 0.025, odds ratio 0.28, 95% confidence interval (95% CI) 0.06 to 0.89) was observed. However, after adjusting for gender, age at time of RA diagnosis, and the presence of shared epitope, rheumatoid factor and classic CV risk factors in the Cox regression analysis, this reduction of CV events in CCR5Δ32 allele carriers was slightly outside the range of significance (P = 0.097; hazard ratio 0.37 (95% CI 0.12 to 1.19)). Carriers of the CCR5Δ32 deletion also showed higher FMD values than the remaining patients (CCR5/CCR5Δ32 patients: 7.03% ± 6.61% versus CCR5/CCR5 patients: 5.51% ± 4.66%). This difference was statistically significant when analysis of covariance was performed (P = 0.024). Conclusions Our results show a potential influence of the CCR5Δ32 deletion on the risk of CV disease among patients with RA. This may be due to a protective effect of this allelic variant against the development of vascular endothelial dysfunction

Evaluación de los recursos solares utilizando entornos SIG: el problema de la resolución del Modelo Digital del Terreno

Ponencia presentada en: XXIX Jornadas Científicas de la AME y el VII Encuentro Hispano Luso de Meteorología celebrado en Pamplona, del 24 al 26 de abril de 2006

Antitumor Activity and Mechanism of Action of the Cyclopenta[b]benzofuran, Silvestrol

BACKGROUND. Flavaglines are a family of natural products from the genus Aglaia that exhibit anti-cancer activity in vitro and in vivo and inhibit translation initiation. They have been shown to modulate the activity of eIF4A, the DEAD-box RNA helicase subunit of the eukaryotic initiation factor (eIF) 4F complex, a complex that stimulates ribosome recruitment during translation initiation. One flavagline, silvestrol, is capable of modulating chemosensitivity in a mechanism-based mouse model. METHODOLOGY/PRINCIPAL FINDINGS. Among a number of flavagline family members tested herein, we find that silvestrol is the more potent translation inhibitor among these. We find that silvestrol impairs the ribosome recruitment step of translation initiation by affecting the composition of the eukaryotic initiation factor (eIF) 4F complex. We show that silvestrol exhibits significant anticancer activity in human breast and prostate cancer xenograft models, and that this is associated with increased apoptosis, decreased proliferation, and inhibition of angiogenesis. We demonstrate that targeting translation by silvestrol results in preferential inhibition of weakly initiating mRNAs. CONCLUSIONS/SIGNIFICANCE. Our results indicate that silvestrol is a potent anti-cancer compound in vivo that exerts its activity by affecting survival pathways as well as angiogenesis. We propose that silvestrol mediates its effects by preferentially inhibiting translation of malignancy-related mRNAs. Silvestrol appears to be well tolerated in animals.Canadian Institutes of Health Research (16512, Cancer Consortium Training Grant Award, CancerConsortium Training Grant Award); US Lymphoma Foundation Award; National Institute of Health (RO1 GM073855); National Crime Information Center (017099); Cole Foundation Awar

Tissue Compatibility of SN-38-Loaded Anticancer Nanofiber Matrices

Delivery of chemotherapy in the surgical bed has shown preclinical activity to control cancer progression upon subtotal resection of pediatric solid tumors, but whether this new treatment is safe for tumor‐adjacent healthy tissues remains unknown. Here, Wistar rats are used to study the anatomic and functional impact of electrospun nanofiber matrices eluting SN‐38 a potent chemotherapeutic agent on several body sites where pediatric tumors such as neuroblastoma, Ewing sarcoma, and rhabdomyosarcoma arise. Blank and SN‐38‐loaded matrices embracing the femoral neurovascular bundle or in direct contact with abdominal viscera (liver, kidney, urinary bladder, intestine, and uterus) are placed. Foreign body tissue reaction to the implants is observed though no histologic damage in any tissue/organ. Skin healing is normal. Tissue reaction is similar for SN‐38‐loaded and blank matrices, with the exception of the hepatic capsule that is thicker for the former although within the limits consistent with mild foreign body reaction. Tissue and organ function is completely conserved after local treatments, as assessed by the rotarod test (forelimb function), hematologic tests (liver and renal function), and control of clinical signs. Overall, these findings support the clinical translation of SN‐38‐loaded nanofiber matrices to improve local control strategies of surgically resected tumors