728 research outputs found
Molecular, Enzymatic, and Cellular Characterization of Soluble Adenylyl Cyclase From Aquatic Animals.
The enzyme soluble adenylyl cyclase (sAC) is the most recently identified source of the messenger molecule cyclic adenosine monophosphate. sAC is evolutionarily conserved from cyanobacteria to human, is directly stimulated by [Formula: see text] ions, and can act as a sensor of environmental and metabolic CO2, pH, and [Formula: see text] levels. sAC genes tend to have multiple alternative promoters, undergo extensive alternative splicing, be translated into low mRNA levels, and the numerous sAC protein isoforms may be present in various subcellular localizations. In aquatic organisms, sAC has been shown to mediate various functions including intracellular pH regulation in coral, blood acid/base regulation in shark, heart beat rate in hagfish, and NaCl absorption in fish intestine. Furthermore, sAC is present in multiple other species and tissues, and sAC protein and enzymatic activity have been reported in the cytoplasm, the nucleus, and other subcellular compartments, suggesting even more diverse physiological roles. Although the methods and experimental tools used to study sAC are conventional, the complexity of sAC genes and proteins requires special considerations that are discussed in this chapter
Commensal observing with the Allen Telescope array: software command and control
The Allen Telescope Array (ATA) is a Large-Number-Small-Diameter radio
telescope array currently with 42 individual antennas and 5 independent
back-end science systems (2 imaging FX correlators and 3 time domain beam
formers) located at the Hat Creek Radio Observatory (HCRO). The goal of the ATA
is to run multiple back-ends simultaneously, supporting multiple science
projects commensally. The primary software control systems are based on a
combination of Java, JRuby and Ruby on Rails. The primary control API is
simplified to provide easy integration with new back-end systems while the
lower layers of the software stack are handled by a master observing system.
Scheduling observations for the ATA is based on finding a union between the
science needs of multiple projects and automatically determining an efficient
path to operating the various sub-components to meet those needs. When
completed, the ATA is expected to be a world-class radio telescope, combining
dedicated SETI projects with numerous radio astronomy science projects.Comment: SPIE Conference Proceedings, Software and Cyberinfrastructure for
Astronomy, Nicole M. Radziwill; Alan Bridger, Editors, 77400Z, Vol 774
Virtual Flight Demonstration of the Stratospheric Dual-Aircraft Platform
A baseline configuration for the dual-aircraft platform (DAP) concept is described and evaluated in a physics-based flight dynamics simulations for two month-long missions as a communications relay in the lower stratosphere above central Florida, within 150-miles of downtown Orlando.The DAP configuration features two large glider-like (130 ft wing span) unmanned aerial vehicles connected via a long adjustable cable (total extendible length of 3000 ft) which effectively sail without propulsion using available wind shear. Use of onboard LiDAR wind profilers to forecast wind distributions are found to be necessary to enable the platform to efficiently adjust flight conditions to remain sailing by finding sufficient wind shear across the platform. The aircraft derive power from solar cells, like a conventional solar aircraft, but also extract wind power using the propeller as a turbine when there is an excess of wind shear available.Month-long atmospheric profiles (at 3-5 min intervals) in the vicinity of 60,000-ft are derived from archived data measured by the 50-Mhz Doppler Radar Wind Profiler at Cape Canaveral and used in the DAP flight simulations. A cursory evaluation of these datasets show that sufficient wind shear for DAP sailing is persistent, suggesting that DAP could potentially sail over 90% of the month-long durations even when limited by modest ascent/descent rates.DAP's novel guidance software uses a non-linear constrained optimization technique to define waypoints such that sailing mode of flight is maintained where possible, and minimal thrust is required where sailing is not practical. A set of constraints are identified which result in waypoints that enable efficient flight (i.e., minimal use of propulsion) over the two month-long flight simulations. Waypoint solutions may need to be tabulated for a wide range of potential atmospheric conditions and stored onboard for quick retrieval on a real DAP.DAP's flight control software uses an unconventional mixture of spacecraft and aircraft control techniques. Flight simulations confirms that this controls approach enables the platform to consistently reach successive waypoints over the month-long flight simulations.The ability of DAP to transition between the sailing mode (i.e., cable tension is high) and standard formation flight (i.e., cable tension is low) is a vital capability (e.g., to enable intermittent turns while stationkeeping). A new method to perform these transitions has been identified and characterized with flight simulation which requires special aircraft modifications.The energy-usage of the DAP configuration during two month-long stationkeeping missions over central Florida (i.e., stationkeeping over Orlando) is evaluated and compared to that of a pure solar aircraft of the same weight and aerodynamic performance. DAP is shown to consistently reduce net propulsion usage while simultaneously increasing solar energy capture.A baseline 700 GHz communications system is described and its performance evaluated for the proposed mission over central Florida. It is found that the variable roll orientation of the aircraft would increase the power required to maintain coverage over the stationkeeping radius of 150 miles (e.g., by as much as 100% when DAP is 150 miles from Orlando), compared to level flight. This effect can be mitigated via additional antenna design complexity or a more restricted stationkeeping radius
Uphill Struggle: Impediments and Facilitators to Porter Health in the Khumbu Region
The surge of Nepal’s tourism industry has resulted in new waves of tourists visiting popular trekking areas such as the northern Khumbu region of the Solukhumbu District. One effect of this growing industry has been the increased prominence of porters in the area. Coming mostly from lowlands south of the Khumbu, porters are composed mainly of young individuals looking to make a career in the enticing business of trekking and mountaineering tourism. The current status of porter health in Solukhumbu is poor. Many ailments exist to physical and social well-being, and social segregation, incentives to carry heavier loads and a lack of basic health needs have left the porter population victim to a system that sacrifices health for financial profit.
This study was done to determine the common impediments to porter well-being and to analyze current actions being taken to improve porter health. Interviews were conducted around settlements in Khumbu along the trail from Phaplu to Gokyo. Altitude illness and respiratory infections were common diseases for the regional porter population, and impediments to well-being included inadequacies in equipment, accommodation, insurance and education. Clothing centers, education workshops, porter shelters, awareness campaigns and an insurance program are some of the actions currently being taken in the area to improve porter health, though poor awareness, trekking company influence, and perceptions among porters have prevented widespread use of these resources. Altruism and abandonment were both common themes relating to porter health, highlighting the ethical nature of this topic
The Allen Telescope Array: The First Widefield, Panchromatic, Snapshot Radio Camera for Radio Astronomy and SETI
The first 42 elements of the Allen Telescope Array (ATA-42) are beginning to
deliver data at the Hat Creek Radio Observatory in Northern California.
Scientists and engineers are actively exploiting all of the flexibility
designed into this innovative instrument for simultaneously conducting surveys
of the astrophysical sky and conducting searches for distant technological
civilizations. This paper summarizes the design elements of the ATA, the cost
savings made possible by the use of COTS components, and the cost/performance
trades that eventually enabled this first snapshot radio camera. The
fundamental scientific program of this new telescope is varied and exciting;
some of the first astronomical results will be discussed.Comment: Special Issue of Proceedings of the IEEE: "Advances in Radio
Telescopes", Baars,J. Thompson,R., D'Addario, L., eds, 2009, in pres
Primary Beam and Dish Surface Characterization at the Allen Telescope Array by Radio Holography
The Allen Telescope Array (ATA) is a cm-wave interferometer in California,
comprising 42 antenna elements with 6-m diameter dishes. We characterize the
antenna optical accuracy using two-antenna interferometry and radio holography.
The distortion of each telescope relative to the average is small, with RMS
differences of 1 percent of beam peak value. Holography provides images of dish
illumination pattern, allowing characterization of as-built mirror surfaces.
The ATA dishes can experience mm-scale distortions across -2 meter lengths due
to mounting stresses or solar radiation. Experimental RMS errors are 0.7 mm at
night and 3 mm under worst case solar illumination. For frequencies 4, 10, and
15 GHz, the nighttime values indicate sensitivity losses of 1, 10 and 20
percent, respectively. The ATA.s exceptional wide-bandwidth permits
observations over a continuous range 0.5 to 11.2 GHz, and future retrofits may
increase this range to 15 GHz. Beam patterns show a slowly varying focus
frequency dependence. We probe the antenna optical gain and beam pattern
stability as a function of focus and observation frequency, concluding that ATA
can produce high fidelity images over a decade of simultaneous observation
frequencies. In the day, the antenna sensitivity and pointing accuracy are
affected. We find that at frequencies greater than 5 GHz, daytime observations
greater than 5 GHz will suffer some sensitivity loss and it may be necessary to
make antenna pointing corrections on a 1 to 2 hourly basis.Comment: 19 pages, 23 figures, 3 tables, Authors indicated by an double dagger
({\ddag}) are affiliated with the SETI Institute, Mountain View, CA 95070.
Authors indicated by a section break ({\S}) are affiliated with the Hat Creek
Radio Observatory and/or the Radio Astronomy Laboratory, both affiliated with
the University of California Berkeley, Berkeley C
The Best of All Worlds: Collaborating Across Teams to Produce Quality Videos
Universities need to create their own course content to best teach their students. Creating content, especially multimedia, requires specific skillsets, content knowledge, and an understanding of how people learn. The presenters, a media producer and instructional designer, discuss collaboration strategies and how to be your own instructional designer and media producer
Immunolocalization of Proteins in Corals: The V-Type H\u3csup\u3e+\u3c/sup\u3e-ATPase Proton Pump
Here we describe the immunolocalization of a membrane-bound proton pump, the V-type H+-ATPase (VHA), in tissues and isolated cells of scleractinian corals. Immunolocalization of coral proteins requires additional steps not required for various model organisms, such as decalcification of the coral skeleton for immunohistochemistry or removal of cells away from the skeleton for immunocytochemistry. The tissue and cell preparation techniques described here can be adapted for localization of other coral proteins, provided the appropriate validation steps have been taken for the primary antibodies and species of coral used. These techniques are important for improving our understanding of coral cell physiology
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