261 research outputs found
Increasing Income through Fruit and Vegetable Production Opportunities and Challenges
This report, presented by Thomas Lumpkin, Director General of AVRDC, discusses the current context of global horticulture production and its potential for increasing income. The challenges for developing the horticulture sector are considered in relation to market systems, post-harvest systems and food security and genetic resources. The issue of the environmental impact of horticulture production is addressed with an emphasis on the need for farmers to have access to information on price, quality and safety standards. Capacity building, institutional partnerships and an enabling environment for horticulture production all need to respond to the knowledge intensive nature of horticultural production, ensuring an effective flow of both long-term technical information and dynamic market information. The opportunities provided by horticulture production for women to increase their incomes and for households to improve their health and nutrition are also raised as important factors in reducing rural poverty. This report was discussed at the Stakeholder Meeting at AGM2005
Two adaptation processes in auditory hair cells together can provide an active amplifier
The hair cells of the vertebrate inner ear convert mechanical stimuli to
electrical signals. Two adaptation mechanisms are known to modify the ionic
current flowing through the transduction channels of the hair bundles: a rapid
process involves calcium ions binding to the channels; and a slower adaptation
is associated with the movement of myosin motors. We present a mathematical
model of the hair cell which demonstrates that the combination of these two
mechanisms can produce `self-tuned critical oscillations', i.e. maintain the
hair bundle at the threshold of an oscillatory instability. The characteristic
frequency depends on the geometry of the bundle and on the calcium dynamics,
but is independent of channel kinetics. Poised on the verge of vibrating, the
hair bundle acts as an active amplifier. However, if the hair cell is
sufficiently perturbed, other dynamical regimes can occur. These include slow
relaxation oscillations which resemble the hair bundle motion observed in some
experimental preparations.Comment: 13 pages, 6 figures,REVTeX 4, To appear in Biophysical Journa
The Plume Impingement Contamination II Experiment: Motivation, Design, and Implementation Plan
The International Space Station (ISS) will have a long service life during which it must be able to serve as a capable platform for a wide variety of scientific investigations. In order to provide this capability, the ISS has, at the system level, a design requirement of no more than 100 Angstroms of contaminant deposition per year from "non-quiescent" sources. Non-quiescent sources include the plumes resulting from the firing of reaction control system (ReS) engines on space vehicles visiting the ISS as well as the engines on the ISS itself. Unfortunately, good general plume contamination models do not yet exist. This is due both to the complexity of the problem, making the analytic approach difficult, and to the difficulty in obtaining empirical measurements of contaminant depositions. To address this lack of flight data, NASA Johnson Space Center is planning to fly an experiment, Plume Impingement Contamination-II, to measure the contamination deposition from the Shuttle Orbiter's primary RCS engines as a function angle from plume centerline. This represents the first direct on-orbit measurement of plume impingement contamination away from the nozzle centerline ever performed, and as such is extremely important in validating mathematical models which will be used to quantify the cumulative plume impingement contamination to the ISS over its lifetime. The paper will elaborate further upon the motivation behind making these measurements as well as present the design and implementation plan of this planned experiment
Law Department
The undersigned, under the sanction of the Board of Trustees, will open in Athens, on 1st of October next, a Law School, in connection with the University of Georgia. Believing that such a school is demanded by the wants of the profession and of the State, and looking alone to its own income for the reward of our labor, we shall devote our energies to the effort, which we will not lightly abandon. We expect success only by deserving it. If we deserve it, we shall not fear obtaining it
Obsessive passion: a dependency associated with injury-related risky behaviour in dancers
Grounded in self-determination theory, obsessive passion for an activity has been associated with increased risky behaviour and rigid persistence, both symptomatic of dependence. However, it is unknown whether obsessive passion may predict the development of dependence, and furthermore, theoretically important relationships between basic need satisfaction, passion, exercise dependence and subsequent risky behaviour have not been fully explored. A sample of 100 professional dancers (50fs; 50ms; Mage = 20.88; SD = 2.69) completed self-ratings of risk-related behaviours (doctor visits; following treatment, and warming up), passion for dance and dance dependence. Findings supported the maladaptive nature of obsessive passion in relation to risky behaviour and as predicted dance dependence mediated this relationship. Interestingly, need satisfaction was positively related to both obsessive passion and harmonious passion. Results are discussed in the light of self-determination theory and dysfunctions of obsessive passion, suggesting that professional dancers are at risk of employing maladaptive behaviours if high in obsessive passion, which may be detectable via symptoms of dance dependence
Lagrangian Time Series Models for Ocean Surface Drifter Trajectories
This paper proposes stochastic models for the analysis of ocean surface
trajectories obtained from freely-drifting satellite-tracked instruments. The
proposed time series models are used to summarise large multivariate datasets
and infer important physical parameters of inertial oscillations and other
ocean processes. Nonstationary time series methods are employed to account for
the spatiotemporal variability of each trajectory. Because the datasets are
large, we construct computationally efficient methods through the use of
frequency-domain modelling and estimation, with the data expressed as
complex-valued time series. We detail how practical issues related to sampling
and model misspecification may be addressed using semi-parametric techniques
for time series, and we demonstrate the effectiveness of our stochastic models
through application to both real-world data and to numerical model output.Comment: 21 pages, 10 figure
Many-body spin related phenomena in ultra-low-disorder quantum wires
Zero length quantum wires (or point contacts) exhibit unexplained conductance
structure close to 0.7 X 2e^2/h in the absence of an applied magnetic field. We
have studied the density- and temperature-dependent conductance of
ultra-low-disorder GaAs/AlGaAs quantum wires with nominal lengths l=0 and 2 mu
m, fabricated from structures free of the disorder associated with modulation
doping. In a direct comparison we observe structure near 0.7 X 2e^2/h for l=0
whereas the l=2 mu m wires show structure evolving with increasing electron
density to 0.5 X 2e^2/h in zero magnetic field, the value expected for an ideal
spin-split sub-band. Our results suggest the dominant mechanism through which
electrons interact can be strongly affected by the length of the 1D region.Comment: 5 Pages, 4 figure
Beam based calibration of X-ray pinhole camera in SSRF
The Shanghai Synchrotron Radiation Facility (SSRF) contains a 3.5-GeV storage
ring serving as a national X-ray synchrotron radiation user facility
characterized by a low emittance and a low coupling. The stability and quality
of the electron beams are monitored continuously by an array of diagnostics. In
particular, an X-ray pinhole camera is employed in the diagnostics beamline of
the ring to characterize the position, size, and emittance of the beam. The
performance of the measurement of the transverse electron beam size is given by
the width of the point spread function (PSF) of the X-ray pinhole camera.
Typically the point spread function of the X-ray pinhole camera is calculated
via analytical or numerical method. In this paper we will introduce a new beam
based calibration method to derive the width of the PSF online
The scientific and societal uses of global measurements of subsurface velocity
© The Author(s), 2019. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Szuts, Z. B., Bower, A. S., Donohue, K. A., Girton, J. B., Hummon, J. M., Katsumata, K., Lumpkin, R., Ortner, P. B., Phillips, H. E., Rossby, H. T., Shay, L. K., Sun, C., & Todd, R. E. The scientific and societal uses of global measurements of subsurface velocity. Frontiers in Marine Science, 6, (2019): 358, doi:10.3389/fmars.2019.00358.Ocean velocity defines ocean circulation, yet the available observations of subsurface velocity are under-utilized by society. The first step to address these concerns is to improve visibility of and access to existing measurements, which include acoustic sampling from ships, subsurface float drifts, and measurements from autonomous vehicles. While multiple programs provide data publicly, the present difficulty in finding, understanding, and using these data hinder broader use by managers, the public, and other scientists. Creating links from centralized national archives to project specific websites is an easy but important way to improve data discoverability and access. A further step is to archive data in centralized databases, which increases usage by providing a common framework for disparate measurements. This requires consistent data standards and processing protocols for all types of velocity measurements. Central dissemination will also simplify the creation of derived products tailored to end user goals. Eventually, this common framework will aid managers and scientists in identifying regions that need more sampling and in identifying methods to fulfill those demands. Existing technologies are capable of improving spatial and temporal sampling, such as using ships of opportunity or from autonomous platforms like gliders, profiling floats, or Lagrangian floats. Future technological advances are needed to fill sampling gaps and increase data coverage.This work was supported by the National Science Foundation, United States, Grant Numbers 1356383 to ZBS, OCE 1756361 to ASB at the Woods Hole Oceanographic Institution, and 1536851 to KAD and HTR; the National Oceanographic and Atmospheric Administration, United States, Ocean Observations and Monitoring Division and Atlantic Oceanographic and Meteorological Laboratory to RL; Royal Caribbean Cruise Ltd., to PBO; the Australian Government Department of the Environment and Energy National Environmental Science Programme and Australian Research Council Centre of Excellence for Climate Extremes to HEP; and the Gulf of Mexico Research Initiative Grant V-487 to LS
The CLIMODE field campaign : observing the cycle of convection and restratification over the Gulf Stream
Author Posting. © American Meteorological Society, 2009. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Bulletin of the American Meteorological Society 90 (2009): 1337-1350, doi:10.1175/2009BAMS2706.1.A major oceanographic field experiment is described, which is designed to observe, quantify, and understand the creation and dispersal of weakly stratified fluid known as “mode water” in the region of the Gulf Stream. Formed in the wintertime by convection driven by the most intense air–sea fluxes observed anywhere over the globe, the role of mode waters in the general circulation of the subtropical gyre and its biogeo-chemical cycles is also addressed. The experiment is known as the CLIVAR Mode Water Dynamic Experiment (CLIMODE). Here we review the scientific objectives of the experiment and present some preliminary results.Physical
Oceanography program of NS
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