231 research outputs found
Oh, To Be A Barbarian! Reclaiming Medieval Law and the Exceptional Individual
The desire for the exceptional individual represented is analyzed in this project. The texts in this senior project represent how it is the systems of governance in place, especially during the medieval era in the East and Western-Europe, that celebrate this paradoxical position that the exceptional individual holds within the confines of a structured society. They embrace the chaos these exceptional individuals represent in a way that modern day justice systems find it hard to fathom. The Western-European feudal system encourages hero figures, like Roland, Lancelot, and William Marshal, to emerge from the average honorable man. Similarly in a system seemingly alternate to its Western-European counterpart, the Eastern system of justice, informed by the Holy Law and Islamic jurisprudence, not only allows the common man to be exceptional but rather any man, even the sultans meant to uphold the law. It contains an equalizing nature for all Muslims existing within the Islamic belief system. In Western-European, the exceptional individual who exists outside of the system while also upholding it more often than not must be a nobleman who is either a knight or a common man. It is rare to see a king as an exceptional individual who is applauded for existing outside of the system for the system stems from the throne. The premise of power in Western-Europe comes from the king and thus must be upheld to a degree not attributed to the common man, by said king. In the East, however, while distinction is made between vassal and lord, sultan and commoner, they are all equal in the eyes of their ultimate Lord, Allah (SWT), with this belief acting as the ultimate unifier allowing for even a sultan to be a chaotic individual existing outside of the system yet still an integral part of it. Ultimately however, both of these set structures of justice, to different degrees, promote exceptionalism in individuals in a manner that would be considered rebellion in our modern day. This project works to prove that there has always been a desire in history for the exceptional even if it breaks the rule of law
The Orientation of the Reconnection X-line
We propose a criterion for identifying the orientation of the X-line when two
regions of plasma with arbitrary densities, temperatures, and magnetic fields
undergo reconnection. The X-line points in the direction that maximizes the
(suitably-defined) Alfv\'en speed characterizing the reconnection outflow. For
many situations a good approximation is that the X-line bisects the angle
formed by the magnetic fields
Direct multiscale coupling of a transport code to gyrokinetic turbulence codes
Direct coupling between a transport solver and local, nonlinear gyrokinetic
calculations using the multiscale gyrokinetic code TRINITY [M. Barnes, Ph.D.
thesis, arxiv:0901.2868] is described. The coupling of the microscopic and
macroscopic physics is done within the framework of multiscale gyrokinetic
theory, of which we present the assumptions and key results. An assumption of
scale separation in space and time allows for the simulation of turbulence in
small regions of the space-time grid, which are embedded in a coarse grid on
which the transport equations are implicitly evolved. This leads to a reduction
in computational expense of several orders of magnitude, making
first-principles simulations of the full fusion device volume over the
confinement time feasible on current computing resources. Numerical results
from TRINITY simulations are presented and compared with experimental data from
JET and ASDEX Upgrade plasmas.Comment: 12 pages, 13 figures, invited paper for 2009 APS-DPP meeting,
submitted to Phys. Plasma
Formation and Structure of a Current Sheet in Pulsed-Power Driven Magnetic Reconnection Experiments
We describe magnetic reconnection experiments using a new, pulsed-power
driven experimental platform in which the inflows are super-sonic but
sub-Alfv\'enic.The intrinsically magnetised plasma flows are long lasting,
producing a well-defined reconnection layer that persists over many
hydrodynamic time scales.The layer is diagnosed using a suite of high
resolution laser based diagnostics which provide measurements of the electron
density, reconnecting magnetic field, inflow and outflow velocities and the
electron and ion temperatures.Using these measurements we observe a balance
between the power flow into and out of the layer, and we find that the heating
rates for the electrons and ions are significantly in excess of the classical
predictions. The formation of plasmoids is observed in laser interferometry and
optical self-emission, and the magnetic O-point structure of these plasmoids is
confirmed using magnetic probes.Comment: 14 pages, 12 figures. Accepted for publication in Physics of Plasma
Kinetic formulation and global existence for the Hall-Magneto-hydrodynamics system
This paper deals with the derivation and analysis of the the Hall
Magneto-Hydrodynamic equations. We first provide a derivation of this system
from a two-fluids Euler-Maxwell system for electrons and ions, through a set of
scaling limits. We also propose a kinetic formulation for the Hall-MHD
equations which contains as fluid closure different variants of the Hall-MHD
model. Then, we prove the existence of global weak solutions for the
incompressible viscous resistive Hall-MHD model. We use the particular
structure of the Hall term which has zero contribution to the energy identity.
Finally, we discuss particular solutions in the form of axisymmetric purely
swirling magnetic fields and propose some regularization of the Hall equation
Plasma adiabatic lapse rate
The plasma analog of an adiabatic lapse rate (or temperature variation with
height) in atmospheric physics is obtained. A new source of plasma temperature
gradient in a binary ion species mixture is found that is proportional to the
concentration gradient and difference in average ionization states .
Application to inertial-confinement-fusion implosions indicates a potentially
strong effect in plastic (CH) ablators that is not modeled with mainline
(single-fluid) simulations. An associated plasma thermodiffusion coefficient is
derived, and charge-state diffusion in a single-species plasma is also
predicted
Performance of the IRI-2007 and SAMI2 Models during Extreme Solar Minimum
During the recent solar minimum, solar activity reached the lowest levels observed during the space age. This extremely low solar activity has accompanied a number of unexpected observations in the Earth's ionosphere and thermosphere when compared to previous solar minima. Among these is the fact that the ionosphere is significantly contracted beyond expectations based on empirical models. Data from the CINDI instrument on board C/NOFS is used to evaluate the performance of the IRI-2007 and SAMI2 models during the deepest part of the minimum. Additionally, the inputs to SAMI2 are modified in order to estimate the contributions of a contracted thermosphere and reduced EUV on the resultant ionosphere
Counter-propagating radiative shock experiments on the Orion laser and the formation of radiative precursors
We present results from new experiments to study the dynamics of radiative
shocks, reverse shocks and radiative precursors. Laser ablation of a solid
piston by the Orion high-power laser at AWE Aldermaston UK was used to drive
radiative shocks into a gas cell initially pressurised between and $1.0 \
bar with different noble gases. Shocks propagated at {80 \pm 10 \ km/s} and
experienced strong radiative cooling resulting in post-shock compressions of {
\times 25 \pm 2}. A combination of X-ray backlighting, optical self-emission
streak imaging and interferometry (multi-frame and streak imaging) were used to
simultaneously study both the shock front and the radiative precursor. These
experiments present a new configuration to produce counter-propagating
radiative shocks, allowing for the study of reverse shocks and providing a
unique platform for numerical validation. In addition, the radiative shocks
were able to expand freely into a large gas volume without being confined by
the walls of the gas cell. This allows for 3-D effects of the shocks to be
studied which, in principle, could lead to a more direct comparison to
astrophysical phenomena. By maintaining a constant mass density between
different gas fills the shocks evolved with similar hydrodynamics but the
radiative precursor was found to extend significantly further in higher atomic
number gases (\sim4$ times further in xenon than neon). Finally, 1-D and 2-D
radiative-hydrodynamic simulations are presented showing good agreement with
the experimental data.Comment: HEDLA 2016 conference proceeding
Polymer self-assembly induced enhancement of ice recrystallization inhibition
Ice binding proteins modulate ice nucleation/growth and have huge (bio)technological potential. There are few synthetic materials that reproduce their function, and rational design is challenging due to the outstanding questions about the mechanisms of ice binding, including whether ice binding is essential to reproduce all their macroscopic properties. Here we report that nanoparticles obtained by polymerization-induced self-assembly (PISA) inhibit ice recrystallization (IRI) despite their constituent polymers having no apparent activity. Poly(ethylene glycol), poly(dimethylacrylamide), and poly(vinylpyrrolidone) coronas were all IRI-active when assembled into nanoparticles. Different core-forming blocks were also screened, revealing the core chemistry had no effect. These observations show ice binding domains are not essential for macroscopic IRI activity and suggest that the size, and crowding, of polymers may increase the IRI activity of “non-active” polymers. It was also discovered that poly(vinylpyrrolidone) particles had ice crystal shaping activity, indicating this polymer can engage ice crystal surfaces, even though on its own it does not show any appreciable ice recrystallization inhibition. Larger (vesicle) nanoparticles are shown to have higher ice recrystallization inhibition activity compared to smaller (sphere) particles, whereas ice nucleation activity was not found for any material. This shows that assembly into larger structures can increase IRI activity and that increasing the “size” of an IRI does not always lead to ice nucleation. This nanoparticle approach offers a platform toward ice-controlling soft materials and insight into how IRI activity scales with molecular size of additives
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