7,428 research outputs found
Dancing in the Streets - a design case study
How do you transform a city center at night to enhance the experience of residents and visitors and to combat the publicās fears over safety and security after dark? This challenge was set by the York City Councilās āRenaissance Project: Illuminating York,ā and we took them up on it. We made it our goal to get pedestrians to engage with our interactive light installationāand to get them dancing without even realizing it. People out shopping or on their way to restaurants and nightclubs found themselves followed by ghostly footprints, chased by brightly colored butterflies, playing football with balls of light, or linked together by a ācatās cradleā of colored lines. As they moved within the light projections, participants found that they were literally dancing in the street
Probing the Gamma-Ray Burst Rate with Trigger Simulations of the Swift Burst Alert Telescope
The long gamma-ray burst (GRB) rate is essential for revealing the connection
between GRBs, supernovae and stellar evolution. Additionally, the GRB rate at
high redshift provides a strong probe of star formation history in the early
universe. While hundreds of GRBs are observed by Swift, it remains difficult to
determine the intrinsic GRB rate due to the complex trigger algorithm of Swift.
Current studies usually approximate the Swift trigger algorithm by a single
detection threshold. However, unlike the previously flown GRB instruments,
Swift has over 500 trigger criteria based on photon count rate and additional
image threshold for localization. To investigate possible systematic biases and
explore the intrinsic GRB properties, we developed a program that is capable of
simulating all the rate trigger criteria and mimicking the image trigger
threshold. We use this program to search for the intrinsic GRB rate. Our
simulations show that adopting the complex trigger algorithm of Swift increases
the detection rate of dim bursts. As a result, we find that either the GRB rate
is much higher than previously expected at large redshift, or the luminosity
evolution is non-negligible. We will discuss the best results of the GRB rate
in our search, and their impact on the star-formation history.Comment: 6 pages, 3 figures, 7th Huntsville Gamma-Ray Burst Symposium, GRB
2013: paper 35 in eConf Proceedings C130414
Probing the Cosmic Gamma-Ray Burst Rate with Trigger Simulations of the Swift Burst Alert Telescope
The gamma-ray burst (GRB) rate is essential for revealing the connection
between GRBs, supernovae and stellar evolution. Additionally, the GRB rate at
high redshift provides a strong probe of star formation history in the early
universe. While hundreds of GRBs are observed by Swift, it remains difficult to
determine the intrinsic GRB rate due to the complex trigger algorithm of Swift.
Current studies of the GRB rate usually approximate the Swift trigger algorithm
by a single detection threshold. However, unlike the previously flown GRB
instruments, Swift has over 500 trigger criteria based on photon count rate and
additional image threshold for localization. To investigate possible systematic
biases and explore the intrinsic GRB properties, we develop a program that is
capable of simulating all the rate trigger criteria and mimicking the image
threshold. Our simulations show that adopting the complex trigger algorithm of
Swift increases the detection rate of dim bursts. As a result, our simulations
suggest bursts need to be dimmer than previously expected to avoid
over-producing the number of detections and to match with Swift observations.
Moreover, our results indicate that these dim bursts are more likely to be high
redshift events than low-luminosity GRBs. This would imply an even higher
cosmic GRB rate at large redshifts than previous expectations based on
star-formation rate measurements, unless other factors, such as the luminosity
evolution, are taken into account. The GRB rate from our best result gives a
total number of 4571^{+829}_{-1584} GRBs per year that are beamed toward us in
the whole universe.
SPECIAL NOTE (2015.05.16): This new version incorporates an erratum. All the
GRB rate normalizations () should be a factor of 2 smaller
than previously reported. Please refer to the Appendix for more details. We
sincerely apologize for the mistake.Comment: 52 pages, 17 figures, published in ApJ 783, 24L (2014). An erratum is
included. A typo in Eq. 8 is fixed in this versio
UTP-dependent Inhibition of Na+ Absorption Requires Activation of PKC in Endometrial Epithelial Cells
The objective of this study was to investigate the mechanism of uridine 5ā²-triphosphate (UTP)-dependent inhibition of Na+ absorption in porcine endometrial epithelial cells. Acute stimulation with UTP (5 Ī¼M) produced inhibition of sodium absorption and stimulation of chloride secretion. Experiments using basolateral membraneāpermeabilized cell monolayers demonstrated a reduction in benzamil-sensitive Na+ conductance in the apical membrane after UTP stimulation. The UTP-dependent inhibition of sodium transport could be mimicked by PMA (1 Ī¼M). Several PKC inhibitors, including GF109203X and Gƶ6983 (both nonselective PKC inhibitors) and rottlerin (a PKCĪ“ selective inhibitor), were shown to prevent the UTP-dependent decrease in benzamil-sensitive current. The PKCĪ±-selective inhibitors, Gƶ6976 and PKC inhibitor 20ā28, produced a partial inhibition of the UTP effect on benzamil-sensitive Isc. Inhibition of the benzamil-sensitive Isc by UTP was observed in the presence of BAPTA-AM (50 Ī¼M), confirming that activation of PKCs, and not increases in [Ca2+]i, were directly responsible for the inhibition of apical Na+ channels and transepithelial Na+ absorption
Secondary Electron Yield Measurements of Fermilab's Main Injector Vacuum Vessel
We discuss the progress made on a new installation in Fermilab's Main
Injector that will help investigate the electron cloud phenomenon by making
direct measurements of the secondary electron yield (SEY) of samples irradiated
in the accelerator. In the Project X upgrade the Main Injector will have its
beam intensity increased by a factor of three compared to current operations.
This may result in the beam being subject to instabilities from the electron
cloud. Measured SEY values can be used to further constrain simulations and aid
our extrapolation to Project X intensities. The SEY test-stand, developed in
conjunction with Cornell and SLAC, is capable of measuring the SEY from samples
using an incident electron beam when the samples are biased at different
voltages. We present the design and manufacture of the test-stand and the
results of initial laboratory tests on samples prior to installation.Comment: 3 pp. 3rd International Particle Accelerator Conference (IPAC 2012)
20-25 May 2012, New Orleans, Louisian
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