30,966 research outputs found
Analysis of the effects of interpolation and enhancement of LANDSAT-1 Data on classification and area estimation accuracy
There are no author-identified significant results in this report
On the influence of social bots in online protests. Preliminary findings of a Mexican case study
Social bots can affect online communication among humans. We study this
phenomenon by focusing on #YaMeCanse, the most active protest hashtag in the
history of Twitter in Mexico. Accounts using the hashtag are classified using
the BotOrNot bot detection tool. Our preliminary analysis suggests that bots
played a critical role in disrupting online communication about the protest
movement.Comment: 10 page
Removal of spacecraft-surface particulate contaminants by simulated micrometeoroid impacts
A series of hypervelocity impacts has been conducted in an exploding lithium-wire accelerator to examine with a far-field holographic system the removal of particulate contaminants from external spacecraft surfaces subjected to micrometeoroid bombardment. The impacting projectiles used to simulate the micrometeoroids were glass spheres nominally 37 microns in diameter, having velocities between 4 and 17 km/sec. The particulates were glass spheres nominally 25, 50, and 75 microns in diameter which were placed on aluminum targets. For these test, particulates detached had velocities that were log-normally distributed. The significance of the log-normal behavior of the ejected-particulate velocity distribution is that the geometric mean velocity and the geometric standard deviation are the only two parameters needed to model completely the process of particles removed or ejected from a spacecraft surface by a micrometeoroid impact
On the Non-invasive Measurement of the Intrinsic Quantum Hall Effect
With a model calculation, we demonstrate that a non-invasive measurement of
intrinsic quantum Hall effect defined by the local chemical potential in a
ballistic quantum wire can be achieved with the aid of a pair of voltage leads
which are separated by potential barriers from the wire. B\"uttiker's formula
is used to determine the chemical potential being measured and is shown to
reduce exactly to the local chemical potential in the limit of strong potential
confinement in the voltage leads. Conditions for quantisation of Hall
resistance and measuring local chemical potential are given.Comment: 16 pages LaTex, 2 post-script figures available on reques
Effective non-Markovian description of a system interacting with a bath
We study a harmonic system coupled to chain of first neighbor interacting
oscillators. After deriving the exact dynamics of the system, we prove that one
can effectively describe the exact dynamics by considering a suitable shorter
chain. We provide the explicit expression for such an effective dynamics and we
provide an upper bound on the error one makes considering it instead of the
dynamics of the full chain. We eventually prove how error, timescale and number
of modes in the truncated chain are related
Cellular Ability to Sense Spatial Gradients in the Presence of Multiple Competitive Ligands
Many eukaryotic and prokaryotic cells can exhibit remarkable sensing ability
under small gradient of chemical compound. In this study, we approach this
phenomenon by considering the contribution of multiple ligands to the chemical
kinetics within Michaelis-Menten model. This work was inspired by the recent
theoretical findings from Bo Hu et al. [Phys. Rev. Lett. 105, 048104 (2010)],
our treatment with practical binding energies and chemical potential provides
the results which are consistent with experimental observations.Comment: 5 pages, 4 figure
Testing of a novel web browser interface for the Chinese market
This paper compares the perspicacity, appropriateness and preference of web browser icons from leading software providers with those of a culture-specific design. This online study was conducted in Taiwan and involved 103 participants, who were given three sets of web browser icons to review, namely Microsoft Internet Explorer, Macintosh Safari, and culturally specific icons created using the Culture-Centred Design methodology. The findings of the study show that all three sets have generally high recognition rates, but that some icon functions (e.g. Go/Visit and Favourite) in all three sets have poor recognition rates and are considered inappropriate
Temperature dependence of the ohmic conductivity and activation energy of Pb1+y(Zr0.3Ti0.7)O3 thin films
The ohmic conductivity of the sol-gel derived Pb1+y(Zr0.3Ti0.7)O3 thin films
(with the excess lead y=0.0 to 0.4) are investigated using low frequency small
signal alternate current (AC) and direct current (DC) methods. Its temperature
dependence shows two activation energies of 0.26 and 0.12 eV depending on
temperature range and excess Pb levels. The former is associated with Pb3+
acceptor centers, while the latter could be due to a different defect level yet
to be identified.Comment: 13 pages, 3 figures, PostScript. Submitted to Applied Physics Letter
A COMPARISON OF RUNNING KINEMATICS BETWEEN TOP 6 AND HONG KONG ELITE TRIATHLETES IN 2008 ASIAN CHAMPIONSHIPS
Triathlon is a multi-sport endurance event consists of swimming, cycling, and running in immediate succession between disciplines. A distinguishing feature of running in triathlon is the athlete may need to tolerate fatigue condition and lactate accumulation after exercising two disciplines for an extended period of time. Also, a sudden change of muscle group usage from cycling to running may cause a poor running form in the triathletes. Running is the last discipline in triathlon competition. According to the experience of the coaches, running performance had great effect on the overall result. In order to gather information on the performance of the athletes, on site data collection in high-level competition was conducted. The purpose of this study was to quantify the running kinematics of the triathletes and to determine the running kinematic difference between top 6 male triathletes in running event and HK elite triathletes in 2008 Asian Championships. This information could provide an updated reference on the performance of the Asian top triathletes. Based on the individual result, the strengths and weaknesses in each athlete were identified and specific training program could be provided for skill correction
- …