94 research outputs found
On Perfect Order Subsets in Finite groups
Abstract If G is a finite group and x ∈ G then the set of all elements of G having the same order as x is called an order subset of G determined by x (se
THE INFRASTRUCTURE AND ENVIRONMENT IN THE OLD TENEMENTS IN HANOI
Joint Research on Environmental Science and Technology for the Eart
Measurement of the Upper Tropospheric Density and Temperature Profiles in Hanoi Using a Raman Lidar
The nitrogen molecular density and temperature profiles of the upper troposphere are measured by a Raman lidar system in Hanoi over the range from 3 km to 19 km. The spatial and temporal resolutions of profiles are 60 m and 1h, respectively. The nitrogen molecular density profiles are directly calculated from the range-corrected lidar signal. The temperature profiles are derived from the molecular density profile based on the assumptions of the hydrostatic equilibrium, the ideal-gas law and a fixed nitrogen molecule ratio in the atmosphere. The results of our lidar measurements show good agreement with the MSISE-90 atmospheric model. The maximum errors of density and temperature measurements are 6% and 7%, respectively. We estimated the height of tropopause in Hanoi about 16 km from the derived temperature profile. The measured density and temperature profiles from this Raman lidar can be used for studying the trends and characteristics of the upper troposphere in Hanoi
Depolarization Property of Cirrus Clouds Over Hanoi
Cirrus cloud is one of the most commonly occurring cloud types globally. The clouds are found mainly to consist of floating ice crystals, which can reflect strongly incoming radiation. Lidar measurements provide an opportunity to study the microphysics and ice compositions of cirrus clouds. We have developed a polarization lidar system to measure the depolarization characteristics of the lower atmosphere over Hanoi. From our measurements of cirrus clouds over the period from 2010 to 2012, the depolarization ratio of cirrus clouds is found to be very high ranging from 20% up to 80{\%}, indicating large fraction of backscattering from ice crystals. We find a trend of increasing depolarization ratio with height and decreasing temperature. We also compare our lidar measurements with other results obtained by lidar technique in other regions of the world
Village Baseline Study – Site Analysis Report for My Loi, Ky Anh district, Ha Tinh province – Viet Nam
Data collection for the Village Baseline Study (VBS) of My Loi village in the CCAFS
benchmark site of central Viet Nam took place on 17- 19 October 2014. Focus group
discussions were conducted separately for 45 men and 45 women villagers.. The VBS had
three main topics: map of (1) community resources, (2) organizational landscapes, and (3)
information networks. A seminar was held in December 2014 to seek participants’ feedback.
My Loi village has experienced multiple extreme weather events (temperature and water
stresses, storms and typhoons) throughout the years. The main constraints for agricultural
development and livelihoods are limited water resources and poor conditions of irrigation
systems, which are challenges to improving the agricultural production situation. Moreover,
sand and rock mining have caused water pollution, erosion on riverbanks and loss of
farmland area. Another constraint is marketing, as villagers are not aware of any organization
involved in finding outlets for agricultural products. The potentials for developing innovative
climate-smart solutions in the village are several: farmers have experiences and are interested
in trying new varieties and adjusting farming calendars to improve the situation. Livestock
expansion and agroforests/reforestation hold opportunities for improving household incomes.
Furthermore, at least half of the organisations identified in the region are working to address
food security issues
Monitoring Cirrus Cloud and Tropopause Height over Hanoi Using a Compact Lidar System
Abstract. Cirrus clouds in the upper troposphere and the lower stratosphere have attracted great attention due to their important role and impact on the atmospheric radioactive balance. Because cirrus clouds are located high in the atmosphere, their study requires a high resolution remote sensing technique not only for detection but also for the characterization of their properties. The lidar technique with its inherent high sensitivity and resolution has become an indispensible tool for studying and improving our understanding of cirrus cloud. Using lidar technique we can simultaneously measure the cloud height, thickness and follow its temporal evolution. In this paper we describe the development of a compact and highly sensitive lidar system with the aim to remotely monitor for the first time the cirrus clouds over Hanoi (21001’42’’N, 105051’12’’W). From the lidar data collected during the year 2011. We derive the mean cloud height, location of cloud top, the cloud mean thickness and their temporal evolution. We then compare the location of the cloud top with the position of the tropopause determined the radiosonde data and found good that the distance between cloud top and tropopause remains fairly stable, indicating that generally the top of cirrus clouds is the good tracer of the tropopause. We found that the cirrus clouds are generally located at height between 11.2 to 15 km with average height of 13.4 km. Their thickness is between 0.3 and 3.8 km with average value of 1.7 km. We also compare the properties of cirrus cloud with that observed at other locations around the world based on lidar technique
Evaluation of Anterior Chamber Depth and Anterior Chamber Angle Changing After Phacoemulsification in the Primary Angle Close Suspect Eyes
BACKGROUND: Phacoemulsification surgery has the ability to deeply alter the segment anterior morphology, especially in eye with shallow anterior chamber (AC), narrow anterior chamber angle (ACA). However, the changes of anterior chamber depth (ACD) and ACA on the close angle suspect eyes after phacoemulsification have not been mentioned in many studies. So, we conduct this research.
AIM: To evaluate the alteration in the ACA and ACD after phacoemulsification in the close angle suspect eyes.
METHODS: Interventional study with no control group. Subjects were the primary angle closure suspect (PACS) eyes, that were operated by phacoemulsification with intraocular lens (IOL) at Glaucoma Department of VNIO from December 2017 to October 2018.
RESULTS: 29 PACS eyes with cataract were operated by phacoemulsification with intraocular lens. After 3 months of monitoring, the average ACD augmented from 2.082 ± 0.244 to 3.673 ± 0.222 mm. AOD500 increase from 0.183 ± 0.088 to 0.388 ± 0.132 μm, AOD750 increased from 0.278 ± 0.105 to 0.576 ± 0.149 μm. The TISA500 enlarged from 0.068 ± 0.033 to 0.140 ± 0.052 mm2, TISA750 enlarged from 0.125 ± 0.052 to 0.256 ± 0.089 mm2 at the third month (p < 0.01).
CONCLUSION: Phacoemulsification surgery increases the ACD and enlarged the angle in the PACS eyes
Village Baseline Study – Site Analysis Report Ma village-Yen Binh district, Vietnam
Ma village, Vinh Kien commune, Yen Binh district, Yen Bai province has been
selected to be one of Climate Smart Villages (CSVs) under the CGIAR Research Program on
Climate Change, Agriculture and Food Security (CCAFS) in Southeast Asia. The village
baseline survey (VBS) of Ma village, was therefore conducted as part of the baseline effort.
This VBS aimed to provide baseline information at the village level about some basic
indicators of natural resource utilization, organizational landscapes, and information
networks for weather and agricultural information, which can be compared across sites and
monitored over time. The study was conducted using the method developed and provided by
CCAFS. The study’s findings show that Ma Village is rich and diverse in natural resources.
There are three main resources of vital importance for the local people livelihoods, namely
farmland, forest and water resources. However, improper exploitation and management have
caused negative impacts on these resources. As mentioned by farmers, in the past, farmland
of the village used to be very fertile, but has now become severely degraded due to overexploitation
and improper management. Regarding forest resources: before 1980s, natural
forests existed in large areas and consisted of valuable timber and wild animals. Today, much
of the forest area has been converted to production forests or to food crop production land.
Water resources, including lakes, rivers and streams have been severely polluted with
pollutants from processing cassava, wood and also from animal husbandry and crop
production. Degradation of water, farmland and forest resources are causing increasing
challenges to agricultural production and also to other human activities. Results of farmer
group discussions also demonstrate that there are 34 organizations operating in the village.
Most of them are governmental. Very few are private or non-governmental organizations.
The number of organizations involving in food security accounts for nearly 50%, the figure
for those involving food crisis is 41.6% and in natural resources management is 25%. Those
organizations working in food security and food crisis focus mainly on providing support
(financial, seed and agricultural inputs) to local farmers to implement some production
activities. Insufficient attention and input spent for sustainable development by these 34
organizations, especially those working in the area of natural resources management, could
be one of the main reasons for the degradation and erosion of natural resources. There was no
activity supporting Ma Village to develop production systems which can respond well to
climate change. The study findings however show that local people are very flexible and
creative, especially in exploitation of information. Among media channels, television is the
most popular. Nevertheless, organizations, in particular, extension networks, Farmers’ Union,
local authorities, etc., also have an important role in information dissemination. Exploitation
of information from the internet and mobile phones has also been given attention, but mostly
by young people only
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