172 research outputs found
Tomographic evaluation of the temporomandibular joint in malocclusion subjects: condylar morphology and position
Calibration and Physics with ARA Station 1: A Unique Askaryan Radio Array Detector
The Askaryan Radio Array Station 1 (A1), the first among five autonomous
stations deployed for the ARA experiment at the South Pole, is a unique
ultra-high energy neutrino (UHEN) detector based on the Askaryan effect that
uses Antarctic ice as the detector medium. Its 16 radio antennas (distributed
across 4 strings, each with 2 Vertically Polarized (VPol), 2 Horizontally
Polarized (HPol) receivers), and 2 strings of transmitting antennas
(calibration pulsers, CPs), each with 1 VPol and 1 HPol channel, are deployed
at depths less than 100 m within the shallow firn zone of the 2.8 km thick
South Pole (SP) ice. We apply different methods to calibrate its Ice Ray
Sampler second generation (IRS2) chip for timing offset and ADC-to-Voltage
conversion factors using a known continuous wave input signal to the digitizer,
and achieve a precision of sub-nanoseconds. We achieve better calibration for
odd, compared to even samples, and also find that the HPols under-perform
relative to the VPol channels. Our timing calibrated data is subsequently used
to calibrate the ADC-to-Voltage conversion as well as precise antenna
locations, as a precursor to vertex reconstruction. The calibrated data will
then be analyzed for UHEN signals in the final step of data compression. The
ability of A1 to scan the firn region of SP ice sheet will contribute greatly
towards a 5-station analysis and will inform the design of the planned IceCube
Gen-2 radio array.Comment: 10 page
The Drosophila neural lineages: a model system to study brain development and circuitry
In Drosophila, neurons of the central nervous system are grouped into units called lineages. Each lineage contains cells derived from a single neuroblast. Due to its clonal nature, the Drosophila brain is a valuable model system to study neuron development and circuit formation. To better understand the mechanisms underlying brain development, genetic manipulation tools can be utilized within lineages to visualize, knock down, or over-express proteins. Here, we will introduce the formation and development of lineages, discuss how one can utilize this model system, offer a comprehensive list of known lineages and their respective markers, and then briefly review studies that have utilized Drosophila neural lineages with a look at how this model system can benefit future endeavors
Low-threshold ultrahigh-energy neutrino search with the Askaryan Radio Array
In the pursuit of the measurement of the still-elusive ultrahigh-energy (UHE) neutrino flux at energies of order EeV, detectors using the in-ice Askaryan radio technique have increasingly targeted lower trigger thresholds. This has led to improved trigger-level sensitivity to UHE neutrinos. Working with data collected by the Askaryan Radio Array (ARA), we search for neutrino candidates at the lowest threshold achieved to date, leading to improved analysis-level sensitivities. A neutrino search on a data set with 208.7 days of livetime from the reduced-threshold fifth ARA station is performed, achieving a 68% analysis efficiency over all energies on a simulated mixed-composition neutrino flux with an expected background of 0.10-0.04+0.06 events passing the analysis. We observe one event passing our analysis and proceed to set a neutrino flux limit using a Feldman-Cousins construction. We show that the improved trigger-level sensitivity can be carried through an analysis, motivating the phased array triggering technique for use in future radio-detection experiments. We also include a projection using all available data from this detector. Finally, we find that future analyses will benefit from studies of events near the surface to fully understand the background expected for a large-scale detector
The Calibration of the Geometry and Antenna delay in Askaryan Radio Array Station 4 and 5
The Askaryan Radio Array (ARA) experiment at the South Pole is designed to detect the radio signals produced by ultra high energy cosmic neutrino interactions in the ice. There are 5 independent ARA stations, one of which (A5) includes a low-threshold phased array trigger string. Each ARA station is designed to work as an autonomous detector. The Data Acquisition System in all ARA stations is equipped with the Ice Ray Sampler second-generation (IRS2) chip, a custom-made, application-specific integrated circuit (ASIC) for high-speed sampling and digitization. In this contribution, we describe the methodology used to calibrate the IRS2 digitizer chip and the station geometry, namely the relative timing between each pair of ARA antennas, deployed at 200 m below the Antarctic ice surface, and their geometrical positions in the ice, for ARA stations 4 and 5. Our calibration allows for proper timing correlations between incoming signals, which is crucial for radio vertex reconstruction and thus detection of ultra high energy neutrinos through the Askaryan effect. We achieve a signal timing precision on a sub-nanosecond level and an antenna position precision within 10 cm
Modulatory Communication Signal Performance Is Associated with a Distinct Neurogenomic State in Honey Bees
Studies of animal communication systems have revealed that the perception of a salient signal can cause large-scale changes in brain gene expression, but little is known about how communication affects the neurogenomic state of the sender. We explored this issue by studying honey bees that produce a vibratory modulatory signal. We chose this system because it represents an extreme case of animal communication; some bees perform this behavior intensively, effectively acting as communication specialists. We show large differences in patterns of brain gene expression between individuals producing vibratory signal as compared with carefully matched non-senders. Some of the differentially regulated genes have previously been implicated in the performance of other motor activities, including courtship behavior in Drosophila melanogaster and Parkinson's Disease in humans. Our results demonstrate for the first time a neurogenomic brain state associated with sending a communication signal and provide suggestive glimpses of molecular roots for motor control
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