27,651 research outputs found
Numerical determination of the effective moments of non-spherical particles
Dielectric characterisation of polarisable particles, and prediction of the forces and torques exerted upon them, relies on the knowledge of the effective, induced dipole moment. In turn, through the mechanism of depolarisation, the induced dipole moment of a particle is strongly dependent upon its shape. Since realistic shapes create modelling difficulties, the ‘spherical particle’ approximation is often invoked. However, in many cases, including biological dielectric spectroscopy and dielectrophoresis, this assumption is a poor one. For example, human erythrocytes are essentially oblate spheroids with indented sides, while viruses and bacteria often have elongated cigar shapes. Since shape-dependent polarisation both strongly influences the accuracy of conventional dielectric characterisation methods using Maxwell’s mixture formula and confounds accurate prediction of dielectrophoretic forces and torques, it is important to develop means to treat non-spherical particles. In this paper, we demonstrate a means to extract the dipole moment directly from numerical solutions of the induced electrostatic potential when a particle is placed in a uniform electric field. The accuracy of the method is demonstrated for a range of particle shapes: spherical, ellipsoidal, truncated cylinders and an approximation of an erythrocyte, the red blood cell
Chaos Theory, Theology, and Curriculum: Striving Towards the Impossibility of the Gift
It was once thought that small influences could not have a large impact on a grand scale. However, in the 1960s Edward Lorenz discovered that very small disturbances in weather conditions could have a great effect on huge weather systems. With an understanding of chaos theory, which posits that everything matters, I argue that a life based on the lessons of a theology inspired by postmodernism can provide a lens through which to see and act in this chaotic world. By living by this belief, the ability to give the true gift, which is an impossibility and is always to come, becomes meaningful. Curriculum studies allows for many wide ranging topics to be discussed and because of its wide ranging influence it is the avenue through which creating positive change in the world could occur. Inspiring, or even more specifically, resacralizing education is a mission to awaken the spirit, passion, love, creativity, and imagination that has for so long been deadened to standardization, test scores, and the factory model teaching
Indenture, Marshall County, MS, 11 August 1843
https://egrove.olemiss.edu/aldrichcorr_b/1066/thumbnail.jp
Recent results of the STAR high-energy polarized proton-proton program at RHIC at BNL
The STAR experiment at the Relativistic Heavy-Ion Collider (RHIC) at
Brookhaven National Laboratory (BNL) is carrying out a spin physics program
colliding transverse or longitudinal polarized proton beams at
GeV to gain a deeper insight into the spin structure and
dynamics of the proton. These studies provide fundamental tests of Quantum
Chromodynamics (QCD).
One of the main objectives of the STAR spin physics program is the
determination of the polarized gluon distribution function through a
measurement of the longitudinal double-spin asymmetry, , for various
processes. Recent results will be shown on the measurement of for
inclusive jet production, neutral pion production and charged pion production
at GeV. In addition to these measurements involving longitudinal
polarized proton beams, the STAR collaboration has performed several important
measurements employing transverse polarized proton beams. New results on the
measurement of the transverse single-spin asymmetry, , for forward
neutral pion production and the first measurement of for mid-rapidity
di-jet production will be discussed.Comment: 8 pages, 5 figures, Invited talk given at the 17th International Spin
Physics Symposium (SPIN 2006), October 2006, Kyoto, Japa
The development and deployment of formal methods in the UK
UK researchers have made major contributions to the technical ideas
underpinning formal approaches to the specification and development of computer
systems. Perhaps as a consequence of this, some of the significant attempts to
deploy theoretical ideas into practical environments have taken place in the
UK. The authors of this paper have been involved in formal methods for many
years and both have tracked a significant proportion of the whole story. This
paper both lists key ideas and indicates where attempts were made to use the
ideas in practice. Not all of these deployment stories have been a complete
success and an attempt is made to tease out lessons that influence the
probability of long-term impact.Comment: This work has been submitted to the IEEE for possible publication.
Copyright may be transferred without notice, after which this version may no
longer be accessibl
B_s(d) - bar B_s(d) mixing constraints on flavor changing decays of t and b quarks
We study those dimension 6 effective operators which generate flavor-changing
quark-gluon transitions of the third generation quarks, with t -> g + u(c) and
b -> g + d(s), and which could be of interest for LHC experiments. We analyze
the contribution of these operators to B_s(d) - bar B_s(d) mixing and derive
limits on the corresponding effective couplings from the existing experimental
data. The Standard Model gauge invariance relates these couplings to the
couplings controlling t -> g + u(c). On this basis we derive upper limits for
the branching ratios of these processes. We further show that forthcoming LHC
experiments might be able to probe the studied operators and the physics beyond
the Standard Model related to them.Comment: 6 pages, 1 figur
A Photogrammetric System for Model Attitude Measurement in Hypersonic Wind Tunnels
A series of wind tunnel tests have been conducted to evaluate a multi-camera videogrammetric system designed to measure model attitude in hypersonic facilities. The technique utilizes processed video data and photogrammetric principles for point tracking to compute model position including pitch, roll and yaw. A discussion of the constraints encountered during the design, and a review of the measurement results obtained from the NASA Langley Research Center (LaRC) 31-Inch Mach 10 tunnel are presented
Hot Gas Structure in the Elliptical Galaxy NGC 4472
We present X-ray spectroscopic and morphological analyses using Chandra ACIS
and ROSAT observations of the giant elliptical galaxy NGC 4472 in the Virgo
cluster. We discuss previously unobserved X-ray structures within the extended
galactic corona. In the inner 2' of the galaxy, we find X-ray holes or cavities
with radii of ~2 kpc, corresponding to the position of radio lobes. These holes
were produced during a period of nuclear activity that began 1.2 x 10^7 years
ago and may be ongoing. We also find an asymmetrical edge in the galaxy X-ray
emission 3' (14 kpc) northeast of the core and an ~8' tail (36 kpc) extending
southwest of the galaxy. These two features probably result from the
interaction of NGC 4472 gas with the Virgo gas, which produces compression in
the direction of NGC 4472's infall and an extended tail from ram pressure
stripping. Assuming the tail is in pressure equilibrium with the surrounding
gas, we compute its angle to our line of sight and estimate that its true
extent exceeds 100 kpc. Finally, in addition to emission from the nucleus
(first detected by Soldatenkov, Vikhlinin & Pavlinsky), we detect two small
extended sources within 10'' of the nucleus of the galaxy, both of which have
luminosities of ~7 x 10^38 erg/s.Comment: 25 pages, 11 figures, accepted by Ap
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