613 research outputs found
RURAL INFRASTRUCTURE, TRANSACTIONS COSTS, AND MARKETED SURPLUS IN KENYA
We develop a conceptual framework for quantifying fixed transactions costs facing semisubsistence households. Using household survey data from a sample of 324 Kenyan maize farmers, we generate estimates of household supply and demand schedules, as well as the price bands that they face. Our econometric results indicate that on average the ad valorem tax equivalent of the fixed transactions costs facing the households in our sample is 28%. Additional analysis indicates that both remoteness and infrastructure quality have significant impacts on the size of the transactions costs facing farm households. To the best of our knowledge, ours are the first empirical estimates of the magnitude of transactions costs.Marketing,
The geometry of quantum learning
Concept learning provides a natural framework in which to place the problems
solved by the quantum algorithms of Bernstein-Vazirani and Grover. By combining
the tools used in these algorithms--quantum fast transforms and amplitude
amplification--with a novel (in this context) tool--a solution method for
geometrical optimization problems--we derive a general technique for quantum
concept learning. We name this technique "Amplified Impatient Learning" and
apply it to construct quantum algorithms solving two new problems: BATTLESHIP
and MAJORITY, more efficiently than is possible classically.Comment: 20 pages, plain TeX with amssym.tex, related work at
http://www.math.uga.edu/~hunziker/ and http://math.ucsd.edu/~dmeyer
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Space-Based Capstone: Public-Private-Academic Partnership in the Making
The Electronic Systems Engineering Technology (ESET) Program at Texas A&M University provides a recognized undergraduate program with an emphasis in electronics, communication, embedded systems, testing, instrumentation and control systems. The program combines engineering and industrial knowledge and methods to develop, design, and implement new innovative products through a two-semester long Senior Capstone Project.
Capstone is designed to prepare future engineers by bridging the gap between the classroom and industry. Students are required to form teams of two to six members which allows them to develop the skills necessary to succeed in a diverse industry setting. Each team is required to use their knowledge and skills to design, develop, document, and deliver a real-world project equivalent to the assignments they will soon receive as professional engineers.
Following NASA’s approval for funding the development of a research facility named Hermes, a Capstone team, named Microgravity Automated Research Systems (MARS), was sponsored by T STAR, a local space commercialization company, to develop the electronics portion of the facility. Hermes will reside on the International Space Station for five years in the hopes of streamlining the development of experiments that require extended periods of time in microgravity environments.
The Hermes facility will host and manage up to four experiments at a time while allowing for the downlink of experiment data to an Earth station, and the uplink of commands to change experiment parameters. Experiments will adhere to a power budget and communication standard established by MARS so that experiments can be swapped out during the facility’s lifetime. MARS will work with the Mobile Integrated Solutions Laboratory (MISL), an undergraduate applied research lab, in order to prepare them to maintain support for Hermes in the future.Cockrell School of Engineerin
American Eel: A Symposium. Session Two
Session Two\u27s panel focuses on the socio-economic and cultural significance of American eels. The discussion covers an overview of eel fisheries, socio-economic uses, international eel markets, dominance of Asian aquaculture, and the role of the American eel for aquaculture seed stock and for the consumption market
American Eel: A Symposium. Session Two
Session Two\u27s panel focuses on the socio-economic and cultural significance of American eels. The discussion covers an overview of eel fisheries, socio-economic uses, international eel markets, dominance of Asian aquaculture, and the role of the American eel for aquaculture seed stock and for the consumption market
Gravity-Assist Mechanical Simulator for Outreach
There is no convenient way to demonstrate mechanically, as an outreach (or inreach) topic, the angular momentum trade-offs and the conservation of angular momentum associated with gravityassist interplanetary trajectories. The mechanical concepts that underlie gravity assist are often misunderstood or confused, possibly because there is no mechanical analog to it in everyday experience. The Gravity Assist Mech - anical Simulator is a hands-on solution to this longstanding technical communications challenge. Users intuitively grasp the concepts, meeting specific educational objectives. A manually spun wheel with high angular mass and low-friction bearings supplies momentum to an attached spherical neodymium magnet that represents a planet orbiting the Sun. A steel bearing ball following a trajectory across a glass plate above the wheel and magnet undergoes an elastic collision with the revolving magnet, illustrating the gravitational elastic collision between spacecraft and planet on a gravity-assist interplanetary trajectory. Manually supplying the angular momentum for the elastic collision, rather than observing an animation, intuitively conveys the concepts, meeting nine specific educational objectives. Many NASA and JPL interplanetary missions are enabled by the gravity-assist technique
Pando: Personal Volunteer Computing in Browsers
The large penetration and continued growth in ownership of personal
electronic devices represents a freely available and largely untapped source of
computing power. To leverage those, we present Pando, a new volunteer computing
tool based on a declarative concurrent programming model and implemented using
JavaScript, WebRTC, and WebSockets. This tool enables a dynamically varying
number of failure-prone personal devices contributed by volunteers to
parallelize the application of a function on a stream of values, by using the
devices' browsers. We show that Pando can provide throughput improvements
compared to a single personal device, on a variety of compute-bound
applications including animation rendering and image processing. We also show
the flexibility of our approach by deploying Pando on personal devices
connected over a local network, on Grid5000, a French-wide computing grid in a
virtual private network, and seven PlanetLab nodes distributed in a wide area
network over Europe.Comment: 14 pages, 12 figures, 2 table
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Integrating Smart Ceiling Fans and Communicating Thermostats to Provide Energy-Efficient Comfort
The project goal was to identify and test the integration of smart ceiling fans and communicating thermostats. These highly efficient ceiling fans use as much power as an LED light bulb and have onboard temperature and occupancy sensors for automatic operationbased on space conditions. The Center for the Environment (CBE) at UC Berkeley led the research team including TRC, Association for Energy Affordability (AEA), and Big Ass Fans (BAF). The research team conducted laboratory tests, installed99 ceiling fans and 12 thermostats in four affordable multifamily housing sites in California’s Central Valley, interviewed stakeholders to develop a case study, developed an online design tool and design guide, outlined codes and standards outreach, and published several papers.The project team raised indoor cooling temperature setpoints and used ceiling fans as the first stage of cooling; this sequencing of ceiling fans and air conditioningreducesenergy consumption, especially during peak periods, while providing thermal comfort.The field demonstration resulted in 39% measured compressor energy savings during the April–October cooling seasoncompared to baseline conditions, normalized for floor area. Weather-normalized energy use varied from a 36% increase to 71% savings, withmedian savings of 15%.This variability reflects the diversity in buildings, mechanical systems, prior operation settings, space types, andoccupants’ schedules,preferences, and motivations. All commercial spaces with regular occupancy schedules (and twoof the irregularly-occupied commercial spaces and one of the homes) showed energy savings on an absolute basis before normalizing for warmer intervention temperatures,and 10 of 13 sites showed energy savings on a weather-normalized basis. The ceiling fans provided cooling for one site for months during hot weather when the coolingequipment failed.Occupants reported high satisfaction with the ceiling fans and improved thermal comfort. This technology can apply to new and retrofit residential and commercial buildings
Role of Doctoral Studies on the Relationships Between Select Doctoral Students and Their Partners: A Collective Case Study
Students who enter post-baccalaureate studies face numerable challenges during their tenure in graduate school. Although researchers have studied these inherent challenges, a gap exists in the literature concerning doctoral students and the impact of their studies on their personal relationships. As such, the purpose of this collective case study was to examine the effect that doctoral studies have on the relationships between select doctoral students and their partners. Semi-structured interviews of six participants, selected via convenience sampling (i.e., current doctoral students who have been in relationships during their doctoral studies), generated data concerning challenges, coping mechanisms, personal emotions, and relationship concerns. These findings provided a composite understanding of the potential inherent struggles of doctoral students and the corresponding role that their doctoral studies have on the relationships of these specific doctoral students and their partners that matched much of the findings noted in the literature. It is the researchers’ hope that the results will help guide future researchers but urge caution concerning the generalizability of the information gained from this study due to its small sample size
Over-expression of copper/zinc superoxide dismutase in the median preoptic nucleus attenuates chronic angiotensin II-induced hypertension in the rat.
The brain senses circulating levels of angiotensin II (AngII) via circumventricular organs, such as the subfornical organ (SFO), and is thought to adjust sympathetic nervous system output accordingly via this neuro-hormonal communication. However, the cellular signaling mechanisms involved in these communications remain to be fully understood. Previous lesion studies of either the SFO, or the downstream median preoptic nucleus (MnPO) have shown a diminution of the hypertensive effects of chronic AngII, without providing a clear explanation as to the intracellular signaling pathway(s) involved. Additional studies have reported that over-expressing copper/zinc superoxide dismutase (CuZnSOD), an intracellular superoxide (O2·-) scavenging enzyme, in the SFO attenuates chronic AngII-induced hypertension. Herein, we tested the hypothesis that overproduction of O2·- in the MnPO is an underlying mechanism in the long-term hypertensive effects of chronic AngII. Adenoviral vectors encoding human CuZnSOD (AdCuZnSOD) or control vector (AdEmpty) were injected directly into the MnPO of rats implanted with aortic telemetric transmitters for recording of arterial pressure. After a 3 day control period of saline infusion, rats were intravenously infused with AngII (10 ng/kg/min) for ten days. Rats over-expressing CuZnSOD (n = 7) in the MnPO had a blood pressure increase of only 6 ± 2 mmHg after ten days of AngII infusion while blood pressure increased 21 ± 4 mmHg in AdEmpty-infected rats (n = 9). These results support the hypothesis that production of O2·- in the MnPO contributes to the development of chronic AngII-dependent hypertension
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