1,603 research outputs found
Narrow-line Laser Cooling by Adiabatic Transfer
We propose and demonstrate a novel laser cooling mechanism applicable to
particles with narrow-linewidth optical transitions. By sweeping the frequency
of counter-propagating laser beams in a sawtooth manner, we cause adiabatic
transfer back and forth between the ground state and a long-lived optically
excited state. The time-ordering of these adiabatic transfers is determined by
Doppler shifts, which ensures that the associated photon recoils are in the
opposite direction to the particle's motion. This ultimately leads to a robust
cooling mechanism capable of exerting large forces via a weak transition and
with reduced reliance on spontaneous emission. We present a simple intuitive
model for the resulting frictional force, and directly demonstrate its efficacy
for increasing the total phase-space density of an atomic ensemble. We rely on
both simulation and experimental studies using the 7.5~kHz linewidth S
to P transition in Sr. The reduced reliance on spontaneous
emission may allow this adiabatic sweep method to be a useful tool for cooling
particles that lack closed cycling transitions, such as molecules.Comment: 5 pages, 4 figure
Graduate Keynote. Golf Grip Force Evaluation in Individuals with and without Hand Arthritis Using a New Wearable Sensor Technology
BACKGROUND
Hand osteoarthritis (H-OA) is the most common type of osteoarthritis largely affecting individuals over 45. H-OA involves pain, loss of grip strength and limiting participation in recreational activities such as golf. Currently, a number of ‘arthritic’ grips are designed using joint protection principles to ‘reduce hand forces and tight gripping’. However, no comprehensive examinations in their effectiveness have been conducted.
HYPOTHESIS
The purpose of this study is to systematically analyse the hand forces produced from various golf grips and arthritis grips at the distal-phalanges of the hand-grip interface in individuals with and without hand arthritis using new wearable sensor technology.
METHODS
The finger forces in the hand were measured using Pressure Profiles FingerTPS system for participant’s bottom gripping hand thumb, index, middle and ring fingers. The participants performed 3 golf shots using a real ball on artificial turf with 12, mid-iron clubs fitted with various types of standard and arthritis grips.
RESULTS
Preliminary results of 4 healthy participants demonstrated that serrated style golf grips designed for players with arthritis produced some of the highest forces. Also, players with larger hand length measures produce higher forces in smaller diameter grips and small hand length measures in larger diameter grips.
DISCUSSION
These preliminary results demonstrate the possibility that ‘arthritic’ golf grips are not appropriately designed for the given user along with the potential relationship between grip geometry and hand size to finger forces. In better understanding the mechanics of arthritis and its relation to sports, the design of more advanced sporting equipment can be developed
Strategic Policy Choice in State-Level Regulation: The EPA's Clean Power Plan
The EPA's Clean Power Plan sets goals for COâ‚‚ emissions rate reductions by 2030 that vary substantially across states. States can choose the regulatory mechanism they use and whether or not to join with other states in implementing their goals. We analyze incentives to adopt rate standards versus cap-and-trade with theory and simulation. We show conditions where adoption of inefficient rate standards is a dominant strategy from both consumers' and generators' perspectives. Numerical simulations of the western electricity system highlight incentives for uncoordinated policies that lower welfare and increase emissions relative to coordination
Bone density of the femoral neck following Birmingham hip resurfacing: A 2-year prospective study in 27 hips
Background Resurfacing is a popular alternative to a standard hip replacement in young arthritic patients. Despite bone preservation around the femoral component, there is little information regarding the bone quality
The Use of Elastin-like Polypeptides as a Drug Carrier Material: A Compatibility Study
Stimuli responsive self-assembling nanoparticles of elastin-like polypeptides are promising platforms for targeted drug delivery and release. These particles spontaneously assemble from elastin-like polypeptide building blocks in solution. The nanoparticles stably self-assemble under specific temperature, salt, and pH conditions and can dissociate upon changing of these conditions. With appropriate design, the surface of the particles can be decorated with labels that cause them to accumulate in specific diseased tissues. In addition, the size of the particles is appropriate to minimize undesirable rapid clearance from the body. In this study, we are testing the ability of the elastin-like polypeptide core to store and release drugs and model drugs with differing chemical properties. Three chemotherapeutic compounds were loaded into the core of the nanoparticles and the release profile of the drug was determined under conditions that disrupt the particle. This release was compared to baseline release profile of the drug. This study is important in establishing the ability of ELP based nanoparticles to act as triggered drug release vehicles.https://engagedscholarship.csuohio.edu/u_poster_2014/1029/thumbnail.jp
The Melanocortin-4 Receptor Integrates Circadian Light Cues and Metabolism
The melanocortin system directs diverse physiological functions from coat color to body weight homoeostasis. A commonality among melanocortin-mediated processes is that many animals modulate similar processes on a circannual basis in response to longer, summer days, suggesting an underlying link between circadian biology and the melanocortin system. Despite key neuroanatomical substrates shared by both circadian and melanocortin-signaling pathways, little is known about the relationship between the two. Here we identify a link between circadian disruption and the control of glucose homeostasis mediated through the melanocortin-4 receptor (Mc4r). Mc4r-deficient mice exhibit exaggerated circadian fluctuations in baseline blood glucose and glucose tolerance. Interestingly, exposure to lighting conditions that disrupt circadian rhythms improve their glucose tolerance. This improvement occurs through an increase in glucose clearance by skeletal muscle and is food intake and body weight independent. Restoring Mc4r expression to the paraventricular nucleus prevents the improvement in glucose tolerance, supporting a role for the paraventricular nucleus in the integration of circadian light cues and metabolism. Altogether these data suggest that Mc4r signaling plays a protective role in minimizing glucose fluctuations due to circadian rhythms and environmental light cues and demonstrate a previously undiscovered connection between circadian biology and glucose metabolism mediated through the melanocortin system
Dust emissivity in the Submm/Mm: SCUBA and SIMBA observations of Barnard 68
We have observed the dark cloud Barnard 68 with SCUBA at 850 um and with
SIMBA at 1.2 mm. The submillimetre and millimetre dust emission correlate well
with the extinction map of Alves, Lada and Lada (2001).The A_V/850um
correlation is clearly not linear and suggests lower temperatures for the dust
in the inner core of the cloud. Assuming a model for the temperature gradient,
we derive the cloud-averaged dust emissivities (normalised to the V-Band
extinction efficiency) at 850 um and 1.2 mm. We find k_850um/k_V = 4.0 +/- 1.0
x 10^-5 and k_1.2mm/k_V = 9.0 +/- 3.0 x 10^-6. These values are compared with
other determinations in this wavelength regime and with expectations for models
of diffuse dust and grain growth in dense clouds.Comment: 8 pages, 4 figures, A&A accepted (Letter), referee forma
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