3,018 research outputs found
A study of longitudinal oscillations of propellant tanks and wave propagations in feed lines. Part 1 - Propagating pressure waves in a fluid-filled cylindrical shell
Theory and equations for propagating pressure waves in liquid filled cylindrical shell
Anisotropic Inflation from Charged Scalar Fields
We consider models of inflation with U(1) gauge fields and charged scalar
fields including symmetry breaking potential, chaotic inflation and hybrid
inflation. We show that there exist attractor solutions where the anisotropies
produced during inflation becomes comparable to the slow-roll parameters. In
the models where the inflaton field is a charged scalar field the gauge field
becomes highly oscillatory at the end of inflation ending inflation quickly.
Furthermore, in charged hybrid inflation the onset of waterfall phase
transition at the end of inflation is affected significantly by the evolution
of the background gauge field. Rapid oscillations of the gauge field and its
coupling to inflaton can have interesting effects on preheating and
non-Gaussianities.Comment: minor changes, references added, figures are modified, conforms JCAP
published versio
Anisotropic Inflation with Non-Abelian Gauge Kinetic Function
We study an anisotropic inflation model with a gauge kinetic function for a
non-abelian gauge field. We find that, in contrast to abelian models, the
anisotropy can be either a prolate or an oblate type, which could lead to a
different prediction from abelian models for the statistical anisotropy in the
power spectrum of cosmological fluctuations. During a reheating phase, we find
chaotic behaviour of the non-abelian gauge field which is caused by the
nonlinear self-coupling of the gauge field. We compute a Lyapunov exponent of
the chaos which turns out to be uncorrelated with the anisotropy.Comment: 16 pages, 4 figure
Braneworld Flux Inflation
We propose a geometrical model of brane inflation where inflation is driven
by the flux generated by opposing brane charges and terminated by the collision
of the branes, with charge annihilation. We assume the collision process is
completely inelastic and the kinetic energy is transformed into the thermal
energy after collision. Thereafter the two branes coalesce together and behave
as a single brane universe with zero effective cosmological constant. In the
Einstein frame, the 4-dimensional effective theory changes abruptly at the
collision point. Therefore, our inflationary model is necessarily 5-dimensional
in nature. As the collision process has no singularity in 5-dimensional
gravity, we can follow the evolution of fluctuations during the whole history
of the universe. It turns out that the radion field fluctuations have a steeply
tilted, red spectrum, while the primordial gravitational waves have a flat
spectrum. Instead, primordial density perturbations could be generated by a
curvaton mechanism.Comment: 11 pages, 6 figures, references adde
A bivalent recombinant mycobacterium bovis BCG expressing the S1 subunit of the pertussis toxin induces a polyfunctional CD4 <sup>+</sup> T cell immune response
© 2019 Alex I. Kanno et al. Background. A recombinant BCG strain expressing the genetically detoxified S1 subunit of pertussis toxin 9K/129G (rBCG-S1PT), previously constructed by our research group, demonstrated the ability to develop high protection in mouse models of pertussis challenge which correlated with the induction of a Th1 immune response pattern. The Th1 immune response induced by rBCG-S1PT treatment was also confirmed in the murine orthotopic bladder cancer model, in which the intravesical instillation of rBCG-S1PT resulted in an improved antitumor effect. Based on these observations, we hypothesize that the reengineering of the S1PT expression in BCG could increase the efficiency of the protective Th1 immune response in order to develop a new alternative of immunotherapy in bladder cancer treatment. Objectives. To construct rBCG strains expressing S1PT from extrachromosomal (rBCG-S1PT) and integrative vectors (rBCG-Sli), or their combination, generating the bivalent strain (rBCG-S1+S1i), and to evaluate the respective immunogenicity of rBCG strains in mice. Methods. Mycobacterial plasmids were constructed by cloning the s1pt gene under integrative and extrachromosomal vectors and used to transform BCG, individually or in combination. Antigen expression and localization were confirmed by Western blot. Mice were immunized with wild-type BCG or the rBCG strains, and cytokines quantification and flow cytometry analysis were performed in splenocytes culture stimulated with mycobacterial-specific proteins. Findings. S1PT expression was confirmed in all rBCG strains. The extrachromosomal vector directs S1PT to the cell wall-associated fraction, while the integrative vector directs its expression mainly to the intracellular fraction. Higher levels of IFN-γ were observed in the splenocytes culture from the group immunized with rBCG-S1i in comparison to BCG or rBCG-S1PT. rBCG-S1+S1i showed higher levels of CD4 + IFN-γ + and double-positive CD4 + IFN-γ + TNF-α + T cells. Conclusions. rBCG-S1+S1i was able to express the two forms of S1PT and elicited higher induction of polyfunctional CD4 + T cells, indicating enhanced immunogenicity and suggesting its use as immunotherapy for bladder cancer
Early pneumococcal clearance in mice induced by systemic immunization with recombinant BCG PspA-PdT prime and protein boost correlates with cellular and humoral immune response in bronchoalveolar fluids (BALF)
© 2019 The Author(s) An effective immunological response in the lungs during a pneumococcal infection is a key factor to the bacteria clearance and prevention of sepsis. In order to develop broad-range pneumococcal vaccines several pneumococcal proteins and strong adjuvants have been investigated. Previously, we constructed a recombinant BCG (rBCG) strain expressing a fragment of PspA (Pneumococcal surface protein A) fused to PdT (detoxified form of pneumolysin). Immunization of mice with a priming dose of rBCG PspA-PdT followed by a booster dose of rPspA-PdT fused protein induced a high antibody response in the serum and protected mice against lethal challenge. Here, we investigated the humoral and cellular immune response in the Bronchoalveolar lavage fluid (BALF). Immunization of mice with rBCG PspA-PdT / rPspA-PdT induced rapid clearance of bacteria after challenge, an early control of the cellular influx and reduced inflammatory cytokine levels in the BALF. In addition, rBCG PspA-PdT / rPspA-PdT induced higher lymphocyte recruitment to the lungs at 48 h, showing an increased percentage of CD4+ T cells. Furthermore, BALF samples from mice immunized with rBCG PspA-PdT / PspA-PdT showed high binding of IgG2c and enhanced complement deposition on the pneumococcal surface; antibody binding was specific to PspA as no binding was observed to a PspA-knockout strain. Taken together, our results show that the immunization with rBCG PspA-PdT / rPspA-PdT induces humoral and cellular immune responses in the lungs, promotes an early clearance of pneumococci and protects against the systemic dissemination of pneumococci
Issues on Generating Primordial Anisotropies at the End of Inflation
We revisit the idea of generating primordial anisotropies at the end of
inflation in models of inflation with gauge fields. To be specific we consider
the charged hybrid inflation model where the waterfall field is charged under a
U(1) gauge field so the surface of end of inflation is controlled both by
inflaton and the gauge fields. Using delta N formalism properly we find that
the anisotropies generated at the end of inflation from the gauge field
fluctuations are exponentially suppressed on cosmological scales. This is
because the gauge field evolves exponentially during inflation while in order
to generate appreciable anisotropies at the end of inflation the spectator
gauge field has to be frozen and scale invariant. We argue that this is a
generic feature, that is, one can not generate observable anisotropies at the
end of inflation within an FRW background.Comment: V3: new references added, JCAP published versio
Pressure Dependence of Fragile-to-Strong Transition and a Possible Second Critical Point in Supercooled Confined Water
By confining water in nano-pores of silica glass, we can bypass the
crystallization and study the pressure effect on the dynamical behavior in
deeply supercooled state using neutron scattering. We observe a clear evidence
of a cusp-like fragile-to-strong (F-S) dynamic transition. Here we show that
the transition temperature decreases steadily with an increasing pressure,
until it intersects the homogenous nucleation temperature line of bulk water at
a pressure of 1600 bar. Above this pressure, it is no longer possible to
discern the characteristic feature of the F-S transition. Identification of
this end point with the possible second critical point is discussed.Comment: 4 pages, 3 figure
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