16,906 research outputs found
Telling stories, understanding lives, working toward change
Stories are helping us learn more about the livelihoods of the fishers and farmers with whom we work in eastern India. We are engaged with these communities in processes and activities aimed at improving their lives and promoting changes in government policy and service delivery in aquaculture and fisheries. Stories are told in several languages by women and men who fish and farm, about their lives, their livelihoods and significant changes they have experienced. We also record stories as narrated to us by colleague-informants. The written and spoken word, photographs, drawings and films – all are used to document the stories of people’s lives, sometimes prompted by questions as simple as “What do people talk about in the village?” Through the power of language, stories can be an entry point into livelihoods programming, monitoring and evaluation, conflict transformation and ultimately a way of giving life to a rights-based approach to development. (PDF contains 10 pages)
Transmission overhaul and replacement predictions using Weibull and renewel theory
A method to estimate the frequency of transmission overhauls is presented. This method is based on the two-parameter Weibull statistical distribution for component life. A second method is presented to estimate the number of replacement components needed to support the transmission overhaul pattern. The second method is based on renewal theory. Confidence statistics are applied with both methods to improve the statistical estimate of sample behavior. A transmission example is also presented to illustrate the use of the methods. Transmission overhaul frequency and component replacement calculations are included in the example
The Kaipara story: a closer look at the benefits of working together, the evolution of a federation of aquaculture self-help groups and a one-stop aqua shop in rural West Bengal
What is special about Kaipara is that most recently, they have founded a federation of Self-Help Groups that work together to develop their own support network and to draw in the support of others. This is a sophisticated ‘home-grown’ support infrastructure that is the subject of this story. (Pdf contains 8 pages)
Transmission overhaul estimates for partial and full replacement at repair
Timely transmission overhauls increase in-flight service reliability greater than the calculated design reliabilities of the individual aircraft transmission components. Although necessary for aircraft safety, transmission overhauls contribute significantly to aircraft expense. Predictions of a transmission's maintenance needs at the design stage should enable the development of more cost effective and reliable transmissions in the future. The frequency is estimated of overhaul along with the number of transmissions or components needed to support the overhaul schedule. Two methods based on the two parameter Weibull statistical distribution for component life are used to estimate the time between transmission overhauls. These methods predict transmission lives for maintenance schedules which repair the transmission with a complete system replacement or repair only failed components of the transmission. An example illustrates the methods
CEE telecommunications investment and economic growth
The antiquated state of the telecommunications network in the transitional economies of Central and Eastern Europe has been identified by the OECD (1993) and the ITU (1994) as a significant impediment to regional productivity, international competitiveness and trade performance. This situation suggests that the upgrading and extension of the telecommunications network should be a priority objective for policy-makers in order to facilitate growth. This paper empirically examines the relationship between gross fixed investment, telecommunications infrastructure investment and economic growth for a sample of transitional economies in Central and Eastern Europe. In particular, the paper focuses on empirically determining the direction of influence, and timing, between investment and growth.Economies in transition; Investment and growth; Telecommunications infrastructure
Low lift-to-drag aero-assisted orbit transfer vehicles
The results of systems analysis conducted on low life drag ratio (L/D) aero-assisted orbit transfer vehicle (AOTV's) are presented. The objectives for this class of vehicle and formulate technology development plans and funding levels to bring the required technologies to readiness levels, as well as develop a credible decision data base encompassing the entire range of low L/D concepts for use in future NASA Aeroassist Orbit Transfer Vehicles studies. Each candidate low L/D concept, the aerobrake, the lifting brake, and the aeromaneuvering concept could be made to work with technologies achievable by the early 1990's. All concepts require flexible structure with flexible thermal protection system (TPS) to be successfully integrated into the shuttle orbiter for launch, all required improvements in guidance and control to fly the dispersed atmospheres at high altitude, and all concepts had potential to evolve from ground-based to space-based operations
Some economic and social aspects of residential internet use in Australia
This study constructs a profile of the representative Australian residential Internet user from data obtained from a web-based survey. Survey data indicate the representative user is male, 20 to 40 years of age, highly educated, uses the Internet 8 hrs per week for e-mail and FTP, and has a monthly bill of AUD32. Anordered-logit model relates Internet use to price, sociodemographic and connection capacity variables. Model estimates show the probability of higher Internet use is greater for middle-income households, but declines with age of the user. Policy may be required to enhance access to lower-income groups, and to inform the elderly of the potential capabilities of the new technology. Further, model estimates suggest that Australian Internet subscribers prefer flat-rate pricing (or a combination of flat-rate and usagesensitive pricing) over usage-sensitive pricing schemes. This result is consistent with Australian consumer attitudes toward local telephone and mobile cellular pricing.Residential internet use in Australia, economic and social aspects
Bayesian methods of astronomical source extraction
We present two new source extraction methods, based on Bayesian model
selection and using the Bayesian Information Criterion (BIC). The first is a
source detection filter, able to simultaneously detect point sources and
estimate the image background. The second is an advanced photometry technique,
which measures the flux, position (to sub-pixel accuracy), local background and
point spread function. We apply the source detection filter to simulated
Herschel-SPIRE data and show the filter's ability to both detect point sources
and also simultaneously estimate the image background. We use the photometry
method to analyse a simple simulated image containing a source of unknown flux,
position and point spread function; we not only accurately measure these
parameters, but also determine their uncertainties (using Markov-Chain Monte
Carlo sampling). The method also characterises the nature of the source
(distinguishing between a point source and extended source). We demonstrate the
effect of including additional prior knowledge. Prior knowledge of the point
spread function increase the precision of the flux measurement, while prior
knowledge of the background has onlya small impact. In the presence of higher
noise levels, we show that prior positional knowledge (such as might arise from
a strong detection in another waveband) allows us to accurately measure the
source flux even when the source is too faint to be detected directly. These
methods are incorporated in SUSSEXtractor, the source extraction pipeline for
the forthcoming Akari FIS far-infrared all-sky survey. They are also
implemented in a stand-alone, beta-version public tool that can be obtained at
http://astronomy.sussex.ac.uk/rss23/sourceMiner\_v0.1.2.0.tar.gzComment: Accepted for publication by ApJ (this version compiled used
emulateapj.cls
The Born and Markov approximations for atom lasers
We discuss the use of the Born and Markov approximations in describing the
dynamics of an atom laser. In particular, we investigate the applicability of
the quantum optical Born-Markov master equation for describing output coupling.
We derive conditions based on the atomic reservoir, and atom dispersion
relations for when the Born-Markov approximations are valid and discuss
parameter regimes where these approximations fail in our atom laser model.
Differences between the standard optical laser model and the atom laser are due
to a combination of factors, including the parameter regimes in which a typical
atom laser would operate, the different reservoir state which is appropriate
for atoms, and the different dispersion relations between atoms and photons. We
present results based on an exact method in the regimes in which the
Born-Markov approximation fails. The exact solutions in some experimentally
relavent parameter regimes give non-exponential loss of atoms from a cavity.Comment: 10 pages, 3 figures. (2 new figues). Exact solutions have been
included in section II. Sections IV and V have been expanded. A new section
discussing the effects of gravity has been include
Testing Foundations of Biological Scaling Theory Using Automated Measurements of Vascular Networks
Scientists have long sought to understand how vascular networks supply blood
and oxygen to cells throughout the body. Recent work focuses on principles that
constrain how vessel size changes through branching generations from the aorta
to capillaries and uses scaling exponents to quantify these changes. Prominent
scaling theories predict that combinations of these exponents explain how
metabolic, growth, and other biological rates vary with body size.
Nevertheless, direct measurements of individual vessel segments have been
limited because existing techniques for measuring vasculature are invasive,
time consuming, and technically difficult. We developed software that extracts
the length, radius, and connectivity of in vivo vessels from contrast-enhanced
3D Magnetic Resonance Angiography. Using data from 20 human subjects, we
calculated scaling exponents by four methods--two derived from local properties
of branching junctions and two from whole-network properties. Although these
methods are often used interchangeably in the literature, we do not find
general agreement between these methods, particularly for vessel lengths.
Measurements for length of vessels also diverge from theoretical values, but
those for radius show stronger agreement. Our results demonstrate that vascular
network models cannot ignore certain complexities of real vascular systems and
indicate the need to discover new principles regarding vessel lengths
- …
