724 research outputs found
Sweethearts of Boyhood Days
https://digitalcommons.library.umaine.edu/mmb-vp/6571/thumbnail.jp
Data Combinations Accounting for LISA Spacecraft Motion
LISA is an array of three spacecraft in an approximately equilateral triangle
configuration which will be used as a low-frequency gravitational wave
detector. We present here new generalizations of the Michelson- and Sagnac-type
time-delay interferometry data combinations. These combinations cancel laser
phase noise in the presence of different up and down propagation delays in each
arm of the array, and slowly varying systematic motion of the spacecraft. The
gravitational wave sensitivities of these generalized combinations are the same
as previously computed for the stationary cases, although the combinations are
now more complicated. We introduce a diagrammatic representation to illustrate
that these combinations are actually synthesized equal-arm interferometers.Comment: 10 pages, 3 figure
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Design and Integration of a Laser-Based Materials Deposition System
This paper aims to demonstrate the design process of an integrated five-axis Laser-Based Material Deposition (LBMD) system for rapid prototyping application. Several design evaluation methods are selected and applied to the design of the system. A three-dimensional graphical simulation software package was used as a decision making aid and as an analysis tool
in the design process. Hardware integration of a five-axis computer numerical controlled (CNC) vertical milling machine, a 2.5 KW Nd:YAG laser and a linear table is discussed. A brief introduction to the system software and control architecture is also summarized. Some important design issues and considerations specific to Laser Based Material Deposition process are suggested.Mechanical Engineerin
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High speed imaging of Raleigh-Taylor instabilities in laser driven plates
Recent improvements and modifications of the imaging techniques have identified and provided measurements of Raleigh-Taylor (R-T) instabilities that occur in these events. The microscope system in the LLNL Micro Detonics Facility, was converted to an epi-illuminated polarization configuration. A double pulse nanosecond illuminator and a second independently focusable frame camera were also added to the system. A laser driven plate, that is a dense solid driven by a laser heated, lower density plasma, is inherently R-T unstable. The plates are aluminum, deposited on the ends of optical fibers. They are launched by a YAG Laser pulse traveling down the fiber. Plate velocities are several kilometers per second and characteristic dimensions of the instabilities are a few to tens of microns. Several techniques were used to examine the plates, the most successful being specularly reflecting polarization microscopy looking directly at the plate as it flies toward the camera. These images gave data on the spatial frequencies of the instabilities but could not give the amplitudes. To measure the amplitude of the instability a semi- transparent witness plate was placed a known distance from the plate. As above, the plate was observed using the polarization microscope but using the streak camera as the detector. Both the launch of the plate and its impact into the witness plate are observed on the streak record. Knowing the plate velocity function from earlier velocimetry measurements and observing the variations in the arrival time across the plate, the amplitude of the instability can be calculated
We haven't got a seat on the bus for you or All the seats are mine: Narratives and career transitions in professional golf
In this article we explore how the stories an athlete tells throughout life in sport affect her career transition experiences. We base our enquiry on a social constructionist conception of narrative theory which holds that storytelling is integral to the creation and maintenance of identity and sense of self. Life stories were gathered through interviews with two professional women golfers (Christiana and Kandy) over a sixâyear period. Through a narrative analysis of structure and form we explored each participantâs stories of living in and withdrawing from professional golf. We suggest Christiana told monological performanceâoriented stories which, while aligning with the culture of elite sport, resulted in an exclusive athletic identity and foreclosure of alternative selves and roles. On withdrawal, Christiana experienced narrative wreckage, identity collapse, mental health difficulties and considerable psychological trauma. In contrast, Kandy told dialogical discoveryâoriented stories which, while being in tension with the dominant performance narrative, created and sustained a multidimensional identity and self. Her stories and identity remained intact, authentic and continuous on withdrawal from tournament golf and she experienced few psychological problems
Singular potentials and annihilation
We discuss the regularization of attractive singular potentials , by infinitesimal imaginary addition to interaction
constant . Such a procedure enables unique
definition of scattering observables and is equal to an absorption (creation)
of particles in the origin. It is shown, that suggested regularization is an
analytical continuation of the scattering amplitudes of repulsive singular
potential in interaction constant . The nearthreshold properties of
regularized in a mentioned way singular potential are examined. We obtain
expressions for the scattering lengths, which turn to be complex even for
infinitesimal imaginary part of interaction constant. The problem of
perturbation of nearthreshold states of regular potential by a singular one is
treated, the expressions for level shifts and widths are obtained. We show,
that the physical sense of suggested regularization is that the scattering
observables are insensitive to any details of the short range modification of
singular potential, if there exists sufficiently strong inelastic short range
interaction. In this case the scattering observables are determined by
solutions of Schrodinger equation with regularized potential . We point out that the developed formalism can be applied for the
description of systems with short range annihilation, in particular low energy
nucleon-antinucleon scattering.Comment: 10 page
Long-term treatment with the dopamine agonist quinagolide of patients with clinically non-functioning pituitary adenoma
OBJECTIVE: This study was performed to evaluate the effect of prolonged
treatment with the dopamine agonist quinagolide on serum gonadotropin and
alpha-subunit concentrations and tumor volume in patients with clinically
non-functioning pituitary adenomas (CNPA). DESIGN: Ten patients with CNPA
were treated with quinagolide (0.3 mg daily). The median duration of
treatment was 57 months (range 36-93 months). Blood samples for
measurement of serum gonadotropin and alpha-subunit concentrations were
drawn before treatment, after 5 days, and at each outpatient visit.
Computerized tomography or magnetic resonance imaging of the pituitary
region and Goldmann perimetry were done before and at regular intervals
during treatment. RESULTS: A significant decrease of serum FSH, LH or
alpha-subunit concentrations was found in nine patients. The levels
remained low during the entire treatment period. In two out of three
patients with pre-existing visual field defects a slight improvement was
shown during the first months of treatment, but eventually deterioration
occurred in all three patients. A fourth patient developed unilateral
ophthalmoplegia dur
Singular Potentials and Limit Cycles
We show that a central singular potential (with ) is
renormalized by a one-parameter square-well counterterm; low-energy observables
are made independent of the square-well width by adjusting the square-well
strength. We find a closed form expression for the renormalization-group
evolution of the square-well counterterm.Comment: 15 pages LaTex, 5 eps figures, error in figures and text correcte
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