526 research outputs found
FITTING OF PARAMETRIC BUILDING MODELS TO OBLIQUE AERIAL IMAGES
In literature and in photogrammetric workstations many approaches and systems to automatically reconstruct buildings from remote sensing data are described and available. Those building models are being used for instance in city modeling or in cadastre context. If a roof overhang is present, the building walls cannot be estimated correctly from nadir-view aerial images or airborne laser scanning (ALS) data. This leads to inconsistent building outlines, which has a negative inďŹuence on visual impression, but more seriously also represents a wrong legal boundary in the cadaster. Oblique aerial images as opposed to nadir-view images reveal greater detail, enabling to see different views of an object taken from different directions. Building walls are visible from oblique images directly and those images are used for automated roof overhang estimation in this research. A fitting algorithm is employed to find roof parameters of simple buildings. It uses a least squares algorithm to fit projected wire frames to their corresponding edge lines extracted from the images. Self-occlusion is detected based on intersection result of viewing ray and the planes formed by the building whereas occlusion from other objects is detected using an ALS point cloud. Overhang and ground height are obtained by sweeping vertical and horizontal planes respectively. Experimental results are verified with high resolution ortho-images, field survey, and ALS data. Planimetric accuracy of 1cm mean and 5cm standard deviation was obtained, while buildings' orientation were accurate to mean of 0.23° and standard deviation of 0.96° with ortho-image. Overhang parameters were aligned to approximately 10cm with field survey. The ground and roof heights were accurate to mean of – 9cm and 8cm with standard deviations of 16cm and 8cm with ALS respectively. The developed approach reconstructs 3D building models well in cases of sufficient texture. More images should be acquired for completeness of overhang results and automatic accuracy check of roof parameters
A spatially distributed hydroeconomic model to assess the effects of drought on land use, farm profits, and agricultural employment.
In this paper a high-resolution linked hydroeconomic model is demonstrated for drought conditions in a Brazilian river basin.Doi: 10.1029/2008WR00753
Polar opposites? NGOs, left parties and the fight for social change in Nepal
In the early 1990s, when NGOs were rising to prominence as an ostensible force for social change in Nepal, the Maoists were also beginning to organise, and denounced NGOs as agents of imperialism. The Maoists came to prominence by fighting a Peopleâs War launched in 1996, with the intention of improving life for the poor peasant and working-class majority. But after a decade-long struggle, the Maoists became incorporated into the parliamentary system. While Nepalâs first democratic revolution in 1990 met formal, popular political demands, which were consolidated in a subsequent revolution in 2006 overthrowing the monarchy and bringing the Peopleâs War to an end, there was little socio-economic progress for the vast majority. The argument advanced in this article is that this lack of progress relied on the interplay of two phenomena: an anti-Maoist alliance consisting of the international community, the domestic ruling elite and NGOs, and a fundamental ambiguity at the heart of the Maoistsâ political theory
Practice changes beta power at rest and its modulation during movement in healthy subjects but not in patients with Parkinson\u27s disease
Abstract Background PD (Parkinson\u27s disease) is characterized by impairments in cortical plasticity, in beta frequency at rest and in beta power modulation during movement (i.e., eventârelated ERS [synchronization] and ERD [desynchronization]). Recent results with experimental protocols inducing longâterm potentiation in healthy subjects suggest that cortical plasticity phenomena might be reflected by changes of beta power recorded with EEG during rest. Here, we determined whether motor practice produces changes in beta power at rest and during movements in both healthy subjects and patients with PD. We hypothesized that such changes would be reduced in PD. Methods We thus recorded EEG in patients with PD and ageâmatched controls before, during and after a 40âminute reaching task. We determined posttask changes of beta power at rest and assessed the progressive changes of beta ERD and ERS during the task over frontal and sensorimotor regions. Results We found that beta ERS and ERD changed significantly with practice in controls but not in PD. In PD compared to controls, beta power at rest was greater over frontal sensors but posttask changes, like those during movements, were far less evident. In both groups, kinematic characteristics improved with practice; however, there was no correlation between such improvements and the changes in beta power. Conclusions We conclude that prolonged practice in a motor task produces useâdependent modifications that are reflected in changes of beta power at rest and during movement. In PD, such changes are significantly reduced; such a reduction might represent, at least partially, impairment of cortical plasticity
Changes to the World Health Organization guideline on hormonal contraceptive eligibility for women at high risk of HIV: South African perspective and response
The World Health Organization (WHO) published guidelines for hormonal contraceptive eligibility for women at high risk of HIV in March 2017. This guidance followed from a technical consultative meeting convened by the WHO in December 2016, where all the available evidence on hormonal contraceptives and risk of HIV acquisition was reviewed. This was an expert meeting with representation from global experts in family planning and HIV management, including clinicians, epidemiologists, researchers and civil society. The guideline development group, through a consensus, made recommendations to change the medical eligibility criteria for contraceptive use from category 1 to category 2 for progestogen-only injectable contraceptives among women at high risk of HIV. There was no change in the recommendation for all other methods of hormonal contraception. The data that informed this decision are from observational studies, which have limitations; therefore, causality or association of hormonal contraception and risk of HIV acquisition have not been proven. This guidance will have an impact on countries that have a high HIV disease burden and where progestogen-only injectable contraceptives are the highest used, as in South Africa (SA). The information has to be communicated in line with the WHOââŹâ˘s sexual and reproductive health rights principles of ensuring that all women should receive evidence-based recommendations. This will empower them to make informed choices about their reproductive needs. This article seeks to clarify the decision-making process of the WHO and how the new recommendations were formulated. It also gives SAââŹâ˘s response to the guidance and a perspective of what informed the National Department of HealthââŹâ˘s position, taking into account the effect this will have on SAââŹâ˘s contraceptive guidelines
Changes to the World Health Organization guideline on hormonal contraceptive eligibility for women at high risk of HIV: South African perspective and response
The World Health Organization (WHO) published guidelines for hormonal contraceptive eligibility for women at high risk of HIV in March 2017. This guidance followed from a technical consultative meeting convened by the WHO in December 2016, where all the available evidence on hormonal contraceptives and risk of HIV acquisition was reviewed. This was an expert meeting with representation from global experts in family planning and HIV management, including clinicians, epidemiologists, researchers and civil society. The guideline development group, through a consensus, made recommendations to change the medical eligibility criteria for contraceptive use from category 1 to category 2 for progestogen-only injectable contraceptives among women at high risk of HIV. There was no change in the recommendation for all other methods of hormonal contraception. The data that informed this decision are from observational studies, which have limitations; therefore, causality or association of hormonal contraception and risk of HIV acquisition have not been proven. This guidance will have an impact on countries that have a high HIV disease burden and where progestogen-only injectable contraceptives are the highest used, as in South Africa (SA). The information has to be communicated in line with the WHOâs sexual and reproductive health rights principles of ensuring that all women should receive evidence-based recommendations. This will empower them to make informed choices about their reproductive needs. This article seeks to clarify the decision-making process of the WHO and how the new recommendations were formulated. It also gives SAâs response to the guidance and a perspective of what informed the National Department of Healthâs position, taking into account the effect this will have on SAâs contraceptive guidelines
Observation and analysis of spatiotemporal characteristics of surface ozone and carbon monoxide at multiple sites in the Kathmandu Valley, Nepal
Residents of the Kathmandu Valley experience severe particulate
and gaseous air pollution throughout most of the year, even during much of
the rainy season. The knowledge base for understanding the air pollution in
the Kathmandu Valley was previously very limited but is improving rapidly
due to several field measurement studies conducted in the last few years.
Thus far, most analyses of observations in the Kathmandu Valley have been
limited to short periods of time at single locations. This study extends the
past studies by examining the spatial and temporal characteristics of two
important gaseous air pollutants (CO and O3) based on simultaneous
observations over a longer period at five locations within the valley and on
its rim, including a supersite (at Bode in the valley center, 1345 m above
sea level) and four satellite sites: Paknajol (1380 m a.s.l.) in the Kathmandu
city center; Bhimdhunga (1522 m a.s.l.), a mountain pass on the valley's
western rim; Nagarkot (1901 m a.s.l.), another mountain pass on the eastern
rim; and Naikhandi (1233 m a.s.l.), near the valley's only river outlet. CO and
O3 mixing ratios were monitored from January to July 2013, along with
other gases and aerosol particles by instruments deployed at the Bode
supersite during the international air pollution measurement campaign
SusKat-ABC (Sustainable Atmosphere for the Kathmandu Valley â endorsed by
the Atmospheric Brown Clouds program of UNEP). The monitoring of O3 at
Bode, Paknajol and Nagarkot as well as the CO monitoring at Bode were
extended until March 2014 to investigate their variability over a complete
annual cycle. Higher CO mixing ratios were found at Bode than at the outskirt
sites (Bhimdhunga, Naikhandi and Nagarkot), and all sites except Nagarkot
showed distinct diurnal cycles of CO mixing ratio, with morning peaks and
daytime lows. Seasonally, CO was higher during premonsoon (MarchâMay) season
and winter (DecemberâFebruary) season than during monsoon season
(JuneâSeptember) and postmonsoon (OctoberâNovember) season. This is
primarily due to the emissions from brick industries, which are only
operational during this period (JanuaryâApril), as well as increased domestic
heating during winter, and regional forest fires and agro-residue burning
during the premonsoon season. It was lower during the monsoon due to
rainfall, which reduces open burning activities within the valley and in the
surrounding regions and thus reduces sources of CO. The meteorology of the
valley also played a key role in determining the CO mixing ratios. The wind
is calm and easterly in the shallow mixing layer, with a mixing layer height
(MLH) of about 250 m, during the night and early morning. The MLH slowly
increases after sunrise and decreases in the afternoon. As a
result, the westerly wind becomes active and reduces the mixing ratio during
the daytime. Furthermore, there was evidence of an increase in the O3
mixing ratios in the Kathmandu Valley as a result of emissions in the
Indo-Gangetic Plain (IGP) region, particularly from biomass burning
including agro-residue burning. A top-down estimate of the CO emission flux
was made by using the CO mixing ratio and mixing layer height measured at
Bode. The estimated annual CO flux at Bode was 4.9 Âľg mâ2 sâ1,
which is 2â14 times higher than that in widely used emission
inventory databases (EDGAR HTAP, REAS and INTEX-B). This difference in CO
flux between Bode and other emission databases likely arises from large
uncertainties in both the top-down and bottom-up approaches to estimating the
emission flux. The O3 mixing ratio was found to be highest during the
premonsoon season at all sites, while the timing of the seasonal minimum
varied across the sites. The daily maximum 8 h average O3 exceeded
the WHO recommended guideline of 50 ppb on more days at the hilltop station
of Nagarkot (159 out of 357Â days) than at the urban valley bottom sites of Paknajol
(132 out of 354Â days) and Bode (102 out of 353Â days), presumably due to the influence of
free-tropospheric air at the high-altitude site (as also indicated by Putero
et al., 2015, for the Paknajol site in the Kathmandu Valley) as well as to
titration of O3 by fresh NOx emissions near the urban sites. More than
78 % of the exceedance days were during the premonsoon period at all
sites. The high O3 mixing ratio observed during the premonsoon periodÂ
is of a concern for human health and ecosystems, including agroecosystems in
the Kathmandu Valley and surrounding regions.</p
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