180 research outputs found
Equity in the Impact of Title IX on Officiating in the United States
Gender equity in the United States has received considerable attention since the passage of Title IX in 1972. This synthesis seeks to explore the impact on the officiating industry for both male and female referees. Based on a critical mass of research conclusions were drawn to infer how Title IX has helped the officiating industry grow by increasing the job opportunities for officials seeking a career in sports. Conclusions drawn from the critical mass include that there are similarities and differences of female officials to male officials in general. However, the intent of Title IX was to create gender equity. The findings from the current research and conceptual writing on the topic demonstrate that the American sport industry has farther to go in creating equal opportunity for both males and females to benefit from the increased sport participation that has occurred as a result of Title IX. Further, a major finding in this synthesis is that there is inadequate research on Title IX and its impact on the makeup of officials who cover the games that both males and females play. With the female athlete participation rate almost five times that of the pre 1972 rate, why has that not translated over into the officiating realms, this is not clearly understood. In some instances, findings support that female participation in officiating has decreased since the enactment of Title IX. Although not a tenant of gender equity legislation specifically, only a small number of females officiate in the male dominated professional sports. More research is needed on opportunity as well as potential differences in males and females in decision making to determine if this exclusion from male professional sport is warranted or simply an avenue for discrimination that Title IX has not impacted
A picogram and nanometer scale photonic crystal opto-mechanical cavity
We describe the design, fabrication, and measurement of a cavity
opto-mechanical system consisting of two nanobeams of silicon nitride in the
near-field of each other, forming a so-called "zipper" cavity. A photonic
crystal patterning is applied to the nanobeams to localize optical and
mechanical energy to the same cubic-micron-scale volume. The picrogram-scale
mass of the structure, along with the strong per-photon optical gradient force,
results in a giant optical spring effect. In addition, a novel damping regime
is explored in which the small heat capacity of the zipper cavity results in
blue-detuned opto-mechanical damping.Comment: 15 pages, 4 figure
Real-Time Particle Mass Spectrometry Based on Resonant Micro Strings
Micro- and nanomechanical resonators are widely being used as mass sensors due to their unprecedented mass sensitivity. We present a simple closed-form expression which allows a fast and quantitative calculation of the position and mass of individual particles placed on a micro or nano string by measuring the resonant frequency shifts of the first two bending modes. The method has been tested by detecting the mass spectrum of micro particles placed on a micro string. This method enables real-time mass spectrometry necessary for applications such as personal monitoring devices for the assessment of the exposure dose of airborne nanoparticles
Optical and mechanical design of a "zipper" photonic crystal optomechanical cavity
Design of a doubly-clamped beam structure capable of localizing mechanical
and optical energy at the nanoscale is presented. The optical design is based
upon photonic crystal concepts in which patterning of a nanoscale-cross-section
beam can result in strong optical localization to an effective optical mode
volume of 0.2 cubic wavelengths ((\lambda_{c})^3). By placing two identical
nanobeams within the near field of each other, strong optomechanical coupling
can be realized for differential motion between the beams. Current designs for
thin film silicon nitride beams at a wavelength of 1.5 microns indicate that
such structures can simultaneously realize an optical Q-factor of 7x10^6,
motional mass m~40 picograms, mechanical mode frequency ~170 MHz, and an
optomechanical coupling factor (g_{OM}=d\omega_{c}/dx = \omega_{c}/L_{OM}) with
effective length L_{OM} ~ \lambda = 1.5 microns.Comment: 16 pages, 10 figure
Minimization of phonon-tunneling dissipation in mechanical resonators
Micro- and nanoscale mechanical resonators have recently emerged as
ubiquitous devices for use in advanced technological applications, for example
in mobile communications and inertial sensors, and as novel tools for
fundamental scientific endeavors. Their performance is in many cases limited by
the deleterious effects of mechanical damping. Here, we report a significant
advancement towards understanding and controlling support-induced losses in
generic mechanical resonators. We begin by introducing an efficient numerical
solver, based on the "phonon-tunneling" approach, capable of predicting the
design-limited damping of high-quality mechanical resonators. Further, through
careful device engineering, we isolate support-induced losses and perform the
first rigorous experimental test of the strong geometric dependence of this
loss mechanism. Our results are in excellent agreement with theory,
demonstrating the predictive power of our approach. In combination with recent
progress on complementary dissipation mechanisms, our phonon-tunneling solver
represents a major step towards accurate prediction of the mechanical quality
factor.Comment: 12 pages, 4 figure
Slot-mode-coupled optomechanical crystals
We present a design methodology and analysis of a cavity optomechanical
system in which a localized GHz frequency mechanical mode of a nanobeam
resonator is evanescently coupled to a high quality factor (Q>10^6) optical
mode of a separate nanobeam optical cavity. Using separate nanobeams provides
flexibility, enabling the independent design and optimization of the optics and
mechanics of the system. In addition, the small gap (approx. 25 nm) between the
two resonators gives rise to a slot mode effect that enables a large zero-point
optomechanical coupling strength to be achieved, with g/2pi > 300 kHz in a
Si3N4 system at 980 nm and g/2pi approx. 900 kHz in a Si system at 1550 nm. The
fact that large coupling strengths to GHz mechanical oscillators can be
achieved in SiN is important, as this material has a broad optical transparency
window, which allows operation throughout the visible and near-infrared. As an
application of this platform, we consider wide-band optical frequency
conversion between 1300 nm and 980 nm, using two optical nanobeam cavities
coupled on either side to the breathing mode of a mechanical nanobeam
resonator
A microchip optomechanical accelerometer
The monitoring of accelerations is essential for a variety of applications
ranging from inertial navigation to consumer electronics. The basic operation
principle of an accelerometer is to measure the displacement of a flexibly
mounted test mass; sensitive displacement measurement can be realized using
capacitive, piezo-electric, tunnel-current, or optical methods. While optical
readout provides superior displacement resolution and resilience to
electromagnetic interference, current optical accelerometers either do not
allow for chip-scale integration or require bulky test masses. Here we
demonstrate an optomechanical accelerometer that employs ultra-sensitive
all-optical displacement read-out using a planar photonic crystal cavity
monolithically integrated with a nano-tethered test mass of high mechanical
Q-factor. This device architecture allows for full on-chip integration and
achieves a broadband acceleration resolution of 10 \mu g/rt-Hz, a bandwidth
greater than 20 kHz, and a dynamic range of 50 dB with sub-milliwatt optical
power requirements. Moreover, the nano-gram test masses used here allow for
optomechanical back-action in the form of cooling or the optical spring effect,
setting the stage for a new class of motional sensors.Comment: 16 pages, 9 figure
The Importance of Edge Effects on the Intrinsic Loss Mechanisms of Graphene Nanoresonators
We utilize classical molecular dynamics simulations to investigate the
intrinsic loss mechanisms of monolayer graphene nanoresonators undergoing
flexural oscillations. We find that spurious edge modes of vibration, which
arise not due to externally applied stresses but intrinsically due to the
different vibrational properties of edge atoms, are the dominant intrinsic loss
mechanism that reduces the Q-factors. We additionally find that while hydrogen
passivation of the free edges is ineffective in reducing the spurious edge
modes, fixing the free edges is critical to removing the spurious edge-induced
vibrational states. Our atomistic simulations also show that the Q-factor
degrades inversely proportional to temperature; furthermore, we also
demonstrate that the intrinsic losses can be reduced significantly across a
range of operating temperatures through the application of tensile mechanical
strain.Comment: 15 pages, 5 figures. Accepted for publication in Nano Letter
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