476 research outputs found
Interaction Properties of the Periodic and Step-like Solutions of the Double-Sine-Gordon Equation
The periodic and step-like solutions of the double-Sine-Gordon equation are
investigated, with different initial conditions and for various values of the
potential parameter . We plot energy and force diagrams, as functions
of the inter-soliton distance for such solutions. This allows us to consider
our system as an interacting many-body system in 1+1 dimension. We therefore
plot state diagrams (pressure vs. average density) for step-like as well as
periodic solutions. Step-like solutions are shown to behave similarly to their
counterparts in the Sine-Gordon system. However, periodic solutions show a
fundamentally different behavior as the parameter is increased. We
show that two distinct phases of periodic solutions exist which exhibit
manifestly different behavior. Response functions for these phases are shown to
behave differently, joining at an apparent phase transition point.Comment: 17pages, 15 figure
Magnetic Branes in -dimensional Einstein-Maxwell-dilaton gravity
We construct two new classes of spacetimes generated by spinning and
traveling magnetic sources in -dimensional Einstein-Maxwell-dilaton
gravity with Liouville-type potential. These solutions are neither
asymptotically flat nor (A)dS. The first class of solutions which yields a
-dimensional spacetime with a longitudinal magnetic field and
rotation parameters have no curvature singularity and no horizons, but have a
conic geometry. We show that when one or more of the rotation parameters are
nonzero, the spinning branes has a net electric charge that is proportional to
the magnitude of the rotation parameters. The second class of solutions yields
a static spacetime with an angular magnetic field, and have no curvature
singularity, no horizons, and no conical singularity. Although one may add
linear momentum to the second class of solutions by a boost transformation, one
does not obtain a new solution. We find that the net electric charge of these
traveling branes with one or more nonzero boost parameters is proportional to
the magnitude of the velocity of the branes. We also use the counterterm method
and calculate the conserved quantities of the solutions.Comment: 15 pages, the last version to appear in PR
The value of tablets as reading aids for individuals with central visual field loss:an evaluation of eccentric reading with static and scrolling text
Purpose: Technological devices such as smartphones and tablets are widely available and increasingly used as visual aids. This study evaluated the use of a novel app for tablets (MD_evReader) developed as a reading aid for individuals with a central field loss resulting from macular degeneration. The MD_evReader app scrolls text as single lines (similar to a news ticker) and is intended to enhance reading performance using the eccentric viewing technique by both reducing the demands on the eye movement system and minimising the deleterious effects of perceptual crowding. Reading performance with scrolling text was compared with reading static sentences, also presented on a tablet computer. Methods: Twenty-six people with low vision (diagnosis of macular degeneration) read static or dynamic text (scrolled from right to left), presented as a single line at high contrast on a tablet device. Reading error rates and comprehension were recorded for both text formats, and the participantâs subjective experience of reading with the app was assessed using a simple questionnaire. Results: The average reading speed for static and dynamic text was not significantly different and equal to or greater than 85 words per minute. The comprehension scores for both text formats were also similar, equal to approximately 95% correct. However, reading error rates were significantly (p=0.02) less for dynamic text than for static text. The participantsâ questionnaire ratings of their reading experience with the MD_evReader were highly positive and indicated a preference for reading with this app compared with their usual method. Conclusions: Our data show that reading performance with scrolling text is at least equal to that achieved with static text and in some respects (reading error rate) is better than static text. Bespoke apps informed by an understanding of the underlying sensorimotor processes involved in a cognitive task such as reading have excellent potential as aids for people with visual impairments
Quantification and expert evaluation of evidence for chemopredictive biomarkers to personalize cancer treatment.
Predictive biomarkers have the potential to facilitate cancer precision medicine by guiding the optimal choice of therapies for patients. However, clinicians are faced with an enormous volume of often-contradictory evidence regarding the therapeutic context of chemopredictive biomarkers.We extensively surveyed public literature to systematically review the predictive effect of 7 biomarkers claimed to predict response to various chemotherapy drugs: ERCC1-platinums, RRM1-gemcitabine, TYMS-5-fluorouracil/Capecitabine, TUBB3-taxanes, MGMT-temozolomide, TOP1-irinotecan/topotecan, and TOP2A-anthracyclines. We focused on studies that investigated changes in gene or protein expression as predictors of drug sensitivity or resistance. We considered an evidence framework that ranked studies from high level I evidence for randomized controlled trials to low level IV evidence for pre-clinical studies and patient case studies.We found that further in-depth analysis will be required to explore methodological issues, inconsistencies between studies, and tumor specific effects present even within high evidence level studies. Some of these nuances will lend themselves to automation, others will require manual curation. However, the comprehensive cataloging and analysis of dispersed public data utilizing an evidence framework provides a high level perspective on clinical actionability of these protein biomarkers. This framework and perspective will ultimately facilitate clinical trial design as well as therapeutic decision-making for individual patients
Rotating Solution of Einstein-Maxwell Dilaton Gravity with Unusual Asymptotics
We study electrically charged, dilaton black holes, which possess
infinitesimal angular momentum in the presence of one or two Liouville type
potentials. These solutions are neither asymptotically flat nor (anti)-de
Sitter. Some properties of the solutions are discussed.Comment: 11 pages, Accepted (Int. J. Theor. Phys.
Flat galaxies with dark matter halos - existence and stability
We consider a model for a flat, disk-like galaxy surrounded by a halo of dark
matter, namely a Vlasov-Poisson type system with two particle species, the
stars which are restricted to the galactic plane and the dark matter particles.
These constituents interact only through the gravitational potential which
stars and dark matter create collectively. Using a variational approach we
prove the existence of steady state solutions and their nonlinear stability
under suitably restricted perturbations.Comment: 39 page
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A numerical investigation of CO2 dilution on the thermochemical characteristics of a swirl stabilized diffusion flame
The turbulent combustion flow modeling is performed to study the effects of CO2 addition to the fuel and oxidizer streams on the thermochemical characteristics of a swirl stabilized diffusion flame. A flamelet approach along with three well-known turbulence models is utilized to model the turbulent combustion flow field. The k-Ï shear stress transport (SST) model shows the best agreement with the experimental measurements compared with other models. Therefore, the k-Ï SST model is used to study the effects of CO2 dilution on the flame structure and strength, temperature distribution, and CO concentration. To determine the chemical effects of CO2 dilution, a fictitious species is replaced with the regular CO2 in both the fuel stream and the oxidizer stream. The results indicate that the flame temperature decreases when CO2 is added to either the fuel or the oxidizer stream. The flame length reduction is observed at all levels of CO2 dilution. The H radical concentration indicating the flame strength decreases, following by the thermochemical effects of CO2 dilution processes. In comparison with the fictitious species dilution, the chemical effects of CO2 addition enhance the CO mass fraction. The numerical simulations show that when the dilution level is higher, the rate of the flame length reduction is more significant at low swirl numbers
Importance of the Nanofluid Preparation for Ultra-Low Interfacial Tension in Enhanced Oil Recovery Based on Surfactantâ NanoparticleâBrine System Interaction
The main objective of this study is to evaluate the effect of the preparation of the nanofluids based on the interactions between the surfactants, nanoparticles, and brine for being applied in ultra-low interfacial tension (IFT) for an enhanced oil recovery process. Three methodologies for the addition of the saltâsurfactantânanoparticle components for the formulation of an efficient injection fluid were evaluated: order of addition (i) salts, nanoparticles, and surfactants, (ii) salts, surfactants, and then nanoparticles, (iii) surfactants, nanoparticles, and then salts. Also, the effects of the total dissolved solids and the surfactant concentration were evaluated in the interfacial tension for selecting the better formulation of the surfactant solution. Three nanoparticles of different chemical natures were studied: silica gel (SiO2), alumina (Îł-Al2O3), and magnetic iron coreâcarbon shell nanoparticles. The nanoparticles were characterized using dynamic light scattering, zeta-potential, N2 physisorption at â196 °C, and Fourier transform infrared spectroscopy. In addition, the interactions between the surfactant, different types of nanoparticles, and brine were investigated through adsorption isotherms for the three methodologies. The nanofluids based on the different nanoparticles were evaluated through IFT measurements using the spinning drop method. The adsorbed amount of surfactant mixture on nanoparticles decreased in the order of alumina > silica gel > magnetic iron coreâcarbon shell nanoparticles. The minimum IFT achieved was 1 Ă 10â4 mN mâ1 following the methodology II at a coreâshell nanoparticle dosage of 100 mg Lâ1.StefaniÌa
Betancur wants to acknowledge the Departamento
Administrativo de Ciencia, TecnologiÌa
e InnovacioÌn de
Colombia (COLCIENCIAS) for the scholarship received
from call 727â2015. The authors also acknowledge Universidad
Nacional de Colombia, Universidad de Granada,
agreement 3010388 of 2017 with Ecopetrol S.A., agreement
064 of 2018 with COLCIENCIAS and Agencia Nacional de
Hidrocarburos (ANH), Spanish Ministry of Science, Innovation
and Universities, FEDER, contract number RTI2018-
099224-B-I00 and Junta de AndaluciÌa
ref RNM-172 for the
support provide
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