243 research outputs found
A Seasonality Study of the West Virginia Stream Condition Index
The West Virginia Stream Condition Index (WVSCI) has not been rigorously tested for the effects of seasonal data collection. Scientific literature regarding seasonal impacts on biological indices is surprisingly limited. But most literature does agree that seasonal signals are small in comparison to variation between all possible biological conditions. Recently stream data have been collected from a full range of seasons by both West Virginia Department of Environmental Protection and myself. In this study habitat, benthic macroinvertebrate data, and WVSCI values were analyzed for seasonality. For this reason multiple independent data sets were utilized. The analyses covered in this report include the use of box-and-whisker plots, correlation analysis and ANOVAs. Preliminary results indicate that seasonality does impact certain metrics under some seasonal conditions. Among the six metrics that make up the WVSCI, some seasonal signal was detected for EPT Taxa, % Chironomidae, Hilsenhoff Biotic Index, Total Taxa and the WVSCI Index scores. These signals were very inconsistent across multiple, independent data sets. Presently, there are no suggestions for any alterations of the WVSCI that would reduce seasonal signals
Corrugated Silicon Platelet Feed Horn Array for CMB Polarimetry at 150 GHz
Next generation cosmic microwave background (CMB) polarization anisotropy
measurements will feature focal plane arrays with more than 600 millimeter-wave
detectors. We make use of high-resolution photolithography and wafer-scale etch
tools to build planar arrays of corrugated platelet feeds in silicon with
highly symmetric beams, low cross-polarization and low side lobes. A compact
Au-plated corrugated Si feed designed for 150 GHz operation exhibited
performance equivalent to that of electroformed feeds: ~-0.2 dB insertion loss,
<-20 dB return loss from 120 GHz to 170 GHz, <-25 dB side lobes and <-23 dB
cross-polarization. We are currently fabricating a 50 mm diameter array with 84
horns consisting of 33 Si platelets as a prototype for the SPTpol and ACTpol
telescopes. Our fabrication facilities permit arrays up to 150 mm in diameter.Comment: 12 pages; SPIE proceedings for Millimeter, Submillimeter, and
Far-Infrared Detectors and Instrumentation for Astronomy V (Conference 7741,
June 2010, San Diego, CA, USA
Integrating planar circuits with superconducting 3D microwave cavities using tunable low-loss couplers
We design and test a low-loss interface between superconducting 3-dimensional
microwave cavities and 2-dimensional circuits, where the coupling rate is
highly tunable. This interface seamlessly integrates a magnetic antenna and a
Josephson junction based coupling element with a cavity, and we demonstrate
that the introduced loss from this integration only limits the quality factor
to 4.5 million. The cavity external coupling rate can then be tuned from
negligibly small to over 3 orders of magnitude larger than the internal loss
rate with a characteristic time of 3.2 ns. This switching speed does not impose
additional limits on the coupling rate because it is much faster than the
coupling rate. Moreover, the coupler can be controlled by baseband signals to
avoid interference with microwave signals near the cavity or qubit frequencies.
Finally, the coupling element introduces a 0.04 Hz/photon self-Kerr
nonlinearity to the cavity, remaining linear in high photon number operations
Photon-noise limited sensitivity in titanium nitride kinetic inductance detectors
We demonstrate photon-noise limited performance at sub-millimeter wavelengths
in feedhorn-coupled, microwave kinetic inductance detectors (MKIDs) made of a
TiN/Ti/TiN trilayer superconducting film, tuned to have a transition
temperature of 1.4~K. Micro-machining of the silicon-on-insulator wafer
backside creates a quarter-wavelength backshort optimized for efficient
coupling at 250~\micron. Using frequency read out and when viewing a variable
temperature blackbody source, we measure device noise consistent with photon
noise when the incident optical power is ~0.5~pW, corresponding to noise
equivalent powers ~3 W/. This
sensitivity makes these devices suitable for broadband photometric applications
at these wavelengths
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