10,034 research outputs found
Periodic and Localized Solutions of the Long Wave-Short Wave Resonance Interaction Equation
In this paper, we investigate the (2+1) dimensional long wave-short wave
resonance interaction (LSRI) equation and show that it possess the Painlev\'e
property. We then solve the LSRI equation using Painlev\'e truncation approach
through which we are able to construct solution in terms of three arbitrary
functions. Utilizing the arbitrary functions present in the solution, we have
generated a wide class of elliptic function periodic wave solutions and
exponentially localized solutions such as dromions, multidromions, instantons,
multi-instantons and bounded solitary wave solutions.Comment: 13 pages, 6 figure
Approximate perturbed direct homotopy reduction method: infinite series reductions to two perturbed mKdV equations
An approximate perturbed direct homotopy reduction method is proposed and
applied to two perturbed modified Korteweg-de Vries (mKdV) equations with
fourth order dispersion and second order dissipation. The similarity reduction
equations are derived to arbitrary orders. The method is valid not only for
single soliton solution but also for the Painlev\'e II waves and periodic waves
expressed by Jacobi elliptic functions for both fourth order dispersion and
second order dissipation. The method is valid also for strong perturbations.Comment: 8 pages, 1 figur
The preparation, characterization, and pharmacokinetic studies of chitosan nanoparticles loaded with paclitaxel/dimethyl-β-cyclodextrin inclusion complexes.
A novel biocompatible and biodegradable drug-delivery nanoparticle (NP) has been developed to minimize the severe side effects of the poorly water-soluble anticancer drug paclitaxel (PTX) for clinical use. PTX was loaded into the hydrophobic cavity of a hydrophilic cyclodextrin derivative, heptakis (2,6-di-O-methyl)-β-cyclodextrin (DM-β-CD), using an aqueous solution-stirring method followed by lyophilization. The resulting PTX/DM-β-CD inclusion complex dramatically enhanced the solubility of PTX in water and was directly incorporated into chitosan (CS) to form NPs (with a size of 323.9–407.8 nm in diameter) using an ionic gelation method. The formed NPs had a zeta potential of +15.9–23.3 mV and showed high colloidal stability. With the same weight ratio of PTX to CS of 0.7, the loading efficiency of the PTX/DM-β-CD inclusion complex-loaded CS NPs was 30.3-fold higher than that of the PTX-loaded CS NPs. Moreover, it is notable that PTX was released from the DM-β-CD/CS NPs in a sustained-release manner. The pharmacokinetic studies revealed that, compared with reference formulation (Taxol(®)), the PTX/DM-β-CD inclusion complex-loaded CS NPs exhibited a significant increase in AUC(0→24h) (the area under the plasma drug concentration–time curve over the period of 24 hours) and mean residence time by 2.7-fold and 1.4-fold, respectively. Therefore, the novel drug/DM-β-CD inclusion complex-loaded CS NPs have promising applications for the significantly improved delivery and controlled release of the poorly water-soluble drug PTX or its derivatives, thus possibly leading to enhanced therapeutic efficacy and less severe side effects
New variable separation approach: application to nonlinear diffusion equations
The concept of the derivative-dependent functional separable solution, as a
generalization to the functional separable solution, is proposed. As an
application, it is used to discuss the generalized nonlinear diffusion
equations based on the generalized conditional symmetry approach. As a
consequence, a complete list of canonical forms for such equations which admit
the derivative-dependent functional separable solutions is obtained and some
exact solutions to the resulting equations are described.Comment: 19 pages, 2 fig
The investigation of STEM Self-Efficacy and Professional Commitment to Engineering among female high school students
This study employed social cognitive theory and social cognitive career theory (SCCT) as foundations to explore the influence of high school students’ beliefs about female gender roles and female engineer role models on science, technology, engineering, and mathematics (STEM)self-efficacy and professional commitment to engineering. A total of 88 students from a national girls’ high school participated in STEM project-based learning. A survey questionnaire named The STEM Self-efficacy and Professional Commitment to Engineering Questionnaire, developed by the researchers, was administered to collect data, and a structured equation model was employed to confirm the multi-theoretical model developed in this study. The results of this study show that enhancing the gender role beliefs and engineer role models of female students may increase their STEM self-efficacy and professional commitment to engineering. In other words, the female high school students’ professional commitment to engineering model can explain students’ intentions for future engineering careers. Thus, this study suggests integrating STEM project-based learning into the curricula of various schools and integrating female engineer role models into STEM project-based learning activities for female students, which can enhance female high school students’ STEM self-efficacy and professional commitment to engineering.Keywords: female engineer role model; female gender role beliefs; professional commitment to engineering; STEM project-based learning; STEM self-efficac
Evolution of sperm morphology in anurans : Insights into the roles of mating system and spawning location
Background: The degree of postcopulatory sexual selection, comprising variable degrees of sperm competition and cryptic female choice, is an important evolutionary
force to influence sperm form and function. Here we investigated the effects of
mating system and spawning location on the evolution of sperm morphology in 67
species of Chinese anurans. We also examined how relative testes mass as an
indicator of the level of sperm competition affected variation in sperm morphology
across a subset of 29 species.
Results: We found a significant association of mating system and spawning location
with sperm morphology. However, when removing the effects of body mass or
absolute testes mass for species for which such data were available, this effect became
non-significant. Consistent with predictions from sperm competition theory, we found
a positive correlation between sperm morphology and relative testes mass after taking
phylogeny into account.
Conclusions: Our findings suggest that sexual selection in Chinese anurans favors
longer sperm when the level of sperm competition is high. Pre-copulatory male-male
competition and spawning location, on the other hand, do not affect the evolution of
sperm morphology after taking body mass and absolute testes mass into account
From nothing to something: discrete integrable systems
Chinese ancient sage Laozi said that everything comes from `nothing'.
Einstein believes the principle of nature is simple. Quantum physics proves
that the world is discrete. And computer science takes continuous systems as
discrete ones. This report is devoted to deriving a number of discrete models,
including well-known integrable systems such as the KdV, KP, Toda, BKP, CKP,
and special Viallet equations, from `nothing' via simple principles. It is
conjectured that the discrete models generated from nothing may be integrable
because they are identities of simple algebra, model-independent nonlinear
superpositions of a trivial integrable system (Riccati equation), index
homogeneous decompositions of the simplest geometric theorem (the angle
bisector theorem), as well as the M\"obious transformation invariants.Comment: 11 pages, side 10 repor
Dynamic Evolution of a Quasi-Spherical General Polytropic Magnetofluid with Self-Gravity
In various astrophysical contexts, we analyze self-similar behaviours of
magnetohydrodynamic (MHD) evolution of a quasi-spherical polytropic magnetized
gas under self-gravity with the specific entropy conserved along streamlines.
In particular, this MHD model analysis frees the scaling parameter in the
conventional polytropic self-similar transformation from the constraint of
with being the polytropic index and therefore
substantially generalizes earlier analysis results on polytropic gas dynamics
that has a constant specific entropy everywhere in space at all time. On the
basis of the self-similar nonlinear MHD ordinary differential equations, we
examine behaviours of the magnetosonic critical curves, the MHD shock
conditions, and various asymptotic solutions. We then construct global
semi-complete self-similar MHD solutions using a combination of analytical and
numerical means and indicate plausible astrophysical applications of these
magnetized flow solutions with or without MHD shocks.Comment: 21 pages, 7 figures, accepted for publication in APS
A multiple exp-function method for nonlinear differential equations and its application
A multiple exp-function method to exact multiple wave solutions of nonlinear
partial differential equations is proposed. The method is oriented towards ease
of use and capability of computer algebra systems, and provides a direct and
systematical solution procedure which generalizes Hirota's perturbation scheme.
With help of Maple, an application of the approach to the dimensional
potential-Yu-Toda-Sasa-Fukuyama equation yields exact explicit 1-wave and
2-wave and 3-wave solutions, which include 1-soliton, 2-soliton and 3-soliton
type solutions. Two cases with specific values of the involved parameters are
plotted for each of 2-wave and 3-wave solutions.Comment: 12 pages, 16 figure
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