47 research outputs found
Metabolomic profiles are gender, disease and time specific in the interleukin-10 gene-deficient mouse model of inflammatory bowel disease.
Metabolomic profiling can be used to study disease-induced changes in inflammatory bowel diseases (IBD). The aim of this study was to investigate the difference in the metabolomic profile of males and females as they developed IBD. Using the IL-10 gene-deficient mouse model of IBD and wild-type mice, urine at age 4, 6, 8, 12, 16, and 20 weeks was collected and analyzed by nuclear magnetic resonance (NMR) spectroscopy. Multivariate data analysis was employed to assess differences in metabolomic profiles that occurred as a consequence of IBD development and severity (at week 20). These changes were contrasted to those that occurred as a consequence of gender. Our results demonstrate that both IL-10 gene-deficient and wild-type mice exhibit gender-related changes in urinary metabolomic profile over time. Some male-female separating metabolites are common to both IL-10 gene-deficient and control wild-type mice and, therefore, appear to be related predominantly to gender maturation. In addition, we were able to identify gender-separating metabolites that are unique for IL-10 gene-deficient and wild-type mice and, therefore, may be indicative of a gender-specific involvement in the development and severity of the intestinal inflammation. The comparison of the gender-separating metabolomic profile from IL-10 gene-deficient mice and wild-type mice during the development of IBD allowed us to identify changes in profile patterns that appear to be imperative in the development of intestinal inflammation, but yet central to gender-related differences in IBD development. The knowledge of metabolomic profile differences by gender and by disease severity has potential clinical implications in the design of both biomarkers of disease as well as the development of optimal therapies
Spin wave dynamics and the determination of intrinsic Gilbert damping in locally-excited Permalloy thin films
Time-resolved scanning Kerr effect microscopy has been used to study
magnetization dynamics in Permalloy thin films excited by transient magnetic
pulses generated by a micrometer-scale transmission line structure. The results
are consistent with magnetostatic spin wave theory and are supported by
micromagnetic simulations. Magnetostatic volume and surface spin waves are
measured for the same specimen using different bias field orientations and can
be accurately calculated by k-space integrations over all excited plane wave
components. A single damping constant of Gilbert form is sufficient to describe
both scenarios. The nonuniform pulsed field plays a key role in the spin wave
dynamics, with its Fourier transform serving as a weighting function for the
participating modes. The intrinsic Gilbert damping parameter is most
conveniently measured when the spin waves are effectively stationary.Comment: 5 pages, 4 figures, accepted by Phys. Rev. Let
A New Type of Plasma Wakefield Accelerator Driven by Magnetowaves
We present a new concept for a plasma wakefield accelerator driven by
magnetowaves (MPWA). This concept was originally proposed as a viable mechanism
for the "cosmic accelerator" that would accelerate cosmic particles to ultra
high energies in the astrophysical setting. Unlike the more familiar Plasma
Wakefield Accelerator (PWFA) and the Laser Wakefield Accelerator (LWFA) where
the drivers, the charged-particle beam and the laser, are independently
existing entities, MPWA invokes the high-frequency and high-speed whistler mode
as the driver, which is a medium wave that cannot exist outside of the plasma.
Aside from the difference in drivers, the underlying mechanism that excites the
plasma wakefield via the ponderomotive potential is common. Our computer
simulations show that under appropriate conditions, the plasma wakefield
maintains very high coherence and can sustain high-gradient acceleration over
many plasma wavelengths. We suggest that in addition to its celestial
application, the MPWA concept can also be of terrestrial utility. A
proof-of-principle experiment on MPWA would benefit both terrestrial and
celestial accelerator concepts.Comment: revtex4, 4 pages, 6 figure
Magnetowave Induced Plasma Wakefield Acceleration for Ultra High Energy Cosmic Rays
Magnetowave induced plasma wakefield acceleration (MPWA) in a relativistic
astrophysical outflow has been proposed as a viable mechanism for the
acceleration of cosmic particles to ultra high energies. Here we present
simulation results that clearly demonstrate the viability of this mechanism for
the first time. We invoke the high frequency and high speed whistler mode for
the driving pulse. The plasma wakefield so induced validates precisely the
theoretical prediction. We show that under appropriate conditions, the plasma
wakefield maintains very high coherence and can sustain high-gradient
acceleration over a macroscopic distance. Invoking gamma ray burst (GRB) as the
source, we show that MPWA production of ultra high energy cosmic rays (UHECR)
beyond ZeV 10^21 eV is possible.Comment: 4 pages, 4 figure
Measures of Statistical Complexity and Dynamical System Applications
Non UBCUnreviewedAuthor affiliation: University of AlbertaFacult
Theoretical, experimental and numerical simulation study of a radially injected barium disk
Thesis (M.S.) University of Alaska Fairbanks, 1981An Investigation of the dynamics and stability of a high-altitude radial barium plasma injection is performed using theoretical and numerical simulation methods. The barium plasma cloud, injection experiment was conducted on March 16, 1980 and produced several interesting phenomena: (1) Three distinct rings of barium containing irregularities exhibiting collective motion; (2) A region of plasma depletion at the location of injection; (3) A structure of approximately eighteen distinct barium ion rays emanating from the injection location. A collisionless, electrostatic particle simulation model is used to understand the behavior of the plasma, indicating that the initial plasma deformation develops due to an E x B azimuthal velocity shear instability. A theoretical model used for a stability analysis of the plasma is formulated based on the number density distributions of the electrons and ions obtained from the numerical simulation results. The linear stability analysis shows that the number of unstable azimuthal modes created by the velocity shear instability is dependent upon the amount of charge separation occurring in the expanding plasma