251 research outputs found
Gauged Q ball in a piecewise parabolic potential
Q ball solutions are considered within the theory of a complex scalar field
with a gauged
U(1) symmetry and a parabolic-type potential. In the thin-walled limit, we
show explicitly that there is a maximum size for these objects because of the
repulsive Coulomb force. The size of Q ball will increase with the decrease of
local minimum of the potential. And when the two minima degenerate, the energy
stored within the surface of the Q ball becomes significant.
Furthermore, we find an analytic expression for gauged Q ball, which is
beyond the conventional thin-walled limit.Comment: 1 figure
Cosmological dynamics of scalar fields with O(N) symmetry
In this paper, we study the cosmological dynamics of scalar fields with O(N)
symmetry in general potentials. We compare the phase space of the dynamical
systems of the quintessence and phantom and give the conditions for the
existence of various attractors as well as their cosmological implications. We
also show that the existence of tracking attractor in O(N) phantom models
require the potential with , which makes the models with
exponential potential possess no tracking attractor.Comment: 9 pages, 4 figures; Replaced with the version to be published in
Classical and Quantum Gravity. Reference adde
Features of Motion Around Global Monopole in Asymptotically dS/AdS Spacetime
In this paper, we study the motion of test particle and light around the
Global Monopole in asymptotically dS/AdS spacetime. The motion of a test
particle and light in the exterior region of the global monopole in dS/AdS
spacetime has been investigated. Although the test particle's motion is quite
different from the case in asymptotically flat spacetime, the behaviors of
light(null geodesic) remain unchanged except a energy(frequency) shift. Through
a phase-plane analysis, we prove analytically that the existence of a periodic
solution to the equation of motion for a test particle will not be altered by
the presence of cosmological constant and the deficit angle, whose presence
only affects the position and type of the critical point on the phase plane. We
also show that the apparent capture section of the global monopole in dS/AdS
spacetime is quite different from that in flat spacetime.Comment: 15 pages, 4 PS figures, accepted for publication in Class. Quantum
Gra
Parallel momentum distribution of the Si fragments from P
Distribution of the parallel momentum of Si fragments from the breakup
of 30.7 MeV/nucleon P has been measured on C targets. The distribution
has the FWHM with the value of 110.5 23.5 MeV/c which is consistent
quantitatively with Galuber model calculation assuming by a valence proton in
P. The density distribution is also predicted by Skyrme-Hartree-Fock
calculation. Results show that there might exist the proton-skin structure in
P.Comment: 4 pages, 4 figure
Feasibility Study of Dual Energy Radiographic Imaging for Target Localization in Radiotherapy for Lung Tumors
Purpose
Dual-energy (DE) radiographic imaging improves tissue discrimination by separating soft from hard tissues in the acquired images. This study was to establish a mathematic model of DE imaging based on intrinsic properties of tissues and quantitatively evaluate the feasibility of applying the DE imaging technique to tumor localization in radiotherapy.
Methods
We investigated the dependence of DE image quality on the radiological equivalent path length (EPL) of tissues with two phantoms using a stereoscopic x-ray imaging unit. 10 lung cancer patients who underwent radiotherapy each with gold markers implanted in the tumor were enrolled in the study approved by the hospital's Ethics Committee. The displacements of the centroids of the delineated gross tumor volumes (GTVs) in the digitally reconstructed radiograph (DRR) and in the bone-canceled DE image were compared with the averaged displacements of the centroids of gold markers to evaluate the feasibility of using DE imaging for tumor localization.
Results
The results of the phantom study indicated that the contrast-to-noise ratio (CNR) was linearly dependent on the difference of EPL and a mathematical model was established. The objects and backgrounds corresponding to ĂâEPL less than 0.08 are visually indistinguishable in the bone-canceled DE image. The analysis of patient data showed that the tumor contrast in the bone-canceled images was improved significantly as compared with that in the original radiographic images and the accuracy of tumor localization using the DE imaging technique was comparable with that of using fiducial makers.
Conclusion
It is feasible to apply the technique for tumor localization in radiotherapy
Pairing symmetry and properties of iron-based high temperature superconductors
Pairing symmetry is important to indentify the pairing mechanism. The
analysis becomes particularly timely and important for the newly discovered
iron-based multi-orbital superconductors. From group theory point of view we
classified all pairing matrices (in the orbital space) that carry irreducible
representations of the system. The quasiparticle gap falls into three
categories: full, nodal and gapless. The nodal-gap states show conventional
Volovik effect even for on-site pairing. The gapless states are odd in orbital
space, have a negative superfluid density and are therefore unstable. In
connection to experiments we proposed possible pairing states and implications
for the pairing mechanism.Comment: 4 pages, 1 table, 2 figures, polished versio
Phantom with Born-Infield type Lagrangian
Recent analysis of the observation data indicates that the equation of state
of the dark energy might be smaller than -1, which leads to the introduction of
phantom models featured by its negative kinetic energy to account for the
regime of equation of state . In this paper, we generalize the idea to
the Born-Infield type Lagrangian with negative kinetic energy term and give the
condition for the potential, under which the late time attractor solution
exists and also analyze a viable cosmological model in such a scheme.Comment: 13 pages, 6 figures, Reference updated, the final version will be
published in Phys. Rev.
Generation of fusion protein EGFRvIII-HBcAg and its anti-tumor effect in vivo
The epidermal growth factor receptor variant III (EGFRvIII) is the most common variation of EGFR. Because it shows a high frequency in several different types of tumor and has not been detected in normal tissues, it is an ideal target for tumor specific therapy. In this study, we prepared EGFRvIII-HBcAg fusion protein. After immunization with fusion protein, HBcAg or PBS, the titers of antibody in BALB/c mice immunized with fusion protein reached 2.75 Ă 105. Western blot analysis demonstrated that the fusion protein had specific antigenicity against anti-EGFRvIII antibody. Further observation showed fusion protein induced a high frequency of IFN-Îł-secreting lymphocytes. CD4+T cells rather than CD8+T cells were associated with the production of IFN-Îł. Using Renca-vIII(+) cell as specific stimulator, we observed remarkable cytotoxic activity in splenocytes from mice immunized with fusion protein. Mice were challenged with Renca-vIII(+) cells after five times immunization. In fusion protein group, three of ten mice failed to develop tumor and all survived at the end of the research. The weight of tumors in fusion protein were obviously lighter than that in other two groups (t = 4.73, P = 0.044;t = 6.89, P = 0.040). These findings demonstrated that EGFRvIII-HBcAg fusion protein triggered protective responses against tumor expressing EGFRvIII
A Rapid Subtractive Immunization Method to Prepare Discriminatory Monoclonal Antibodies for Food E. coli O157:H7 Contamination
To detect food E. coli O157:H7 contamination rapidly and accurately, it is essential to prepare high specific monoclonal antibodies (mAbs) against the pathogen. Cyclophosphamide (Cy)-mediated subtractive immunization strategy was performed in mice to generate mAbs that react with E. coli O157:H7, but not with other affiliated bacteria. Specificity of 19 mAbs was evaluated by ELISA and/or dot-immunogold filtration assay (DIGFA). Immunogloubin typing, affinity and binding antigens of 5 selected mAbs were also analysed. MAbs 1D8, 4A7, 5A2 were found to have high reactivity with E. coli O157:H7 and no cross-reactivity with 80 other strains of bacteria including Salmonella sp., Shigella sp., Proteus sp., Yersinia enterocolitica, Staphylococcus aureus, Klebsiella pneumoniae, Citrobacter freundii and other non-E. coli O157:H7 enteric bacteria. Their ascetic titers reached 1â¶106 with E. coli O157:H7 and affinity constants ranged from 1.57Ă1010 to 2.79Ă1010 L/mol. The antigens recognized by them were different localized proteins. Furthermore, immune-colloidal gold probe coated with mAb 5A2 could specifically distinguish minced beef contaminated by E. coli O157:H7 from 84 other bacterial contaminations. The Cy-mediated subtractive immunization procedure coupled with hybridoma technology is a rapid and efficient approach to prepare discriminatory mAbs for detection of E. coli O157:H7 contamination in food
Integrated management of ash from industrial and domestic combustion : a new sustainable approach for reducing greenhouse gas emissions from energy conversion
This work supports, for the first time, the integrated management of waste materials arising from industrial processes (fly ash from municipal solid waste incineration and coal fly ash), agriculture (rice husk ash), and domestic activities (ash from wood biomass burning in domestic stoves). The main novelty of the paper is the reuse of wood pellet ash, an underestimated environmental problem, by the application of a new technology (COSMOS-RICE) that already involves the reuse of fly ashes from industrial and agricultural origins. The reaction mechanism involves carbonation: this occurs at room temperature and promotes permanent carbon dioxide sequestration. The obtained samples were characterized using XRD and TGA (coupled with mass spectroscopy). This allowed quantification of the mass loss attributed to different calcium carbonate phases. In particular, samples stabilized using wood pellet ash show a weight loss, attributed to the decomposition of carbonates greater than 20%. In view of these results, it is possible to conclude that there are several environmental benefits from wood pellet ash reuse in this way. In particular, using this technology, it is shown that for wood pellet biomass the carbon dioxide conversion can be considered negative
- âŠ