625 research outputs found
A Qiang Perspective on Promoting the Rehabilitation of Children Affected by the Earthquake
The Qiang ethnic minority had a population of around 300,000 at the time of the earthquake. The Qiang mostly inhabit the poorest and most socially disadvantaged remote rural mountainous areas of the Wen Chuan and Mao Wen Qiang Autonomous Counties of Sichuan. The Qiang have a continuous cultural history dating from the Diqiang groups of the Xia Dynasty (16th to 11th century BC). They have their own language and animistic belief system, and have developed their own traditional ways of dealing with disasters. The Qiangâs myth of âBubitaâ (God) and the legend of âMutazhu and Douanzhuâ (a heroic story) are key messages in understanding disasters; the village âDuyaomaoâ (poisonous cat, meaning witch) is important for explaining childrenâs illness and health. The rites conducted by the Shibi (cultural leader) are the core activity in advocating collective action for responding to disaster. To reach out quickly to children who have been affected by their traumatic experiences, many volunteers have given their assistance, including doctors, psychologists, counselling staff and social workers. In particular, a large-scale program of psychiatric counselling/therapies administered by the government is being carried out. However, employing psychological counselling and psychiatric therapies from the western individualistic perspective has led to a dilemma for public health based on medical/psychological agendas. Widespread evidence has also shown that there is a very limited effect from outside community visitors, whose one-off, inconsistent, non-indigenous messages do not carry over into the childrenâs everyday lives. The need for an indigenous approach is stressed
Energy-Efficient Wireless Communications with Distributed Reconfigurable Intelligent Surfaces
This paper investigates the problem of resource allocation for a wireless
communication network with distributed reconfigurable intelligent surfaces
(RISs). In this network, multiple RISs are spatially distributed to serve
wireless users and the energy efficiency of the network is maximized by
dynamically controlling the on-off status of each RIS as well as optimizing the
reflection coefficients matrix of the RISs. This problem is posed as a joint
optimization problem of transmit beamforming and RIS control, whose goal is to
maximize the energy efficiency under minimum rate constraints of the users. To
solve this problem, two iterative algorithms are proposed for the single-user
case and multi-user case. For the single-user case, the phase optimization
problem is solved by using a successive convex approximation method, which
admits a closed-form solution at each step. Moreover, the optimal RIS on-off
status is obtained by using the dual method. For the multi-user case, a
low-complexity greedy searching method is proposed to solve the RIS on-off
optimization problem. Simulation results show that the proposed scheme achieves
up to 33\% and 68\% gains in terms of the energy efficiency in both single-user
and multi-user cases compared to the conventional RIS scheme and
amplify-and-forward relay scheme, respectively
Application of fractal algorithms of coastline echoâs generation on marine radar simulator
Background: Marine radar simulator is a useful approach endorsed by International Maritime Organization (IMO) to train the seafarers on how to operate marine radar equipment and use marine radar equipment for positioning and collision avoidance in laboratory. To fulfill all of the marine radar simulator training requirements, a high performance simulator is necessary. However, imperfections with currently available marine radar simulators require simulator developers to make improvements.
Case Description: In this study, improved fractal algorithms (random Koch curve, fractional Brownian motion, and Weierstrass-Mandelbrot function) are applied to generate natural-looking radar echoes on a marine radar simulator.
Discussion and evaluation: From the results of the simulations, we can observe that the structures of the coastline echoes generated by improved fractal algorithms, especially by fractional Brownian motion algorithm, outperform the echoes generated by conventional method in representing a natural coastline feature.
Conclusions: Based on evaluations from a panel of experienced mariners, we conclude that the coastline echoes simulated by fractal algorithms better represent a natural coastline feature than those generated by conventional methods
Optimization of User Selection and Bandwidth Allocation for Federated Learning in VLC/RF Systems
Limited radio frequency (RF) resources restrict the number of users that can
participate in federated learning (FL) thus affecting FL convergence speed and
performance. In this paper, we first introduce visible light communication
(VLC) as a supplement to RF in FL and build a hybrid VLC/RF communication
system, in which each indoor user can use both VLC and RF to transmit its FL
model parameters. Then, the problem of user selection and bandwidth allocation
is studied for FL implemented over a hybrid VLC/RF system aiming to optimize
the FL performance. The problem is first separated into two subproblems. The
first subproblem is a user selection problem with a given bandwidth allocation,
which is solved by a traversal algorithm. The second subproblem is a bandwidth
allocation problem with a given user selection, which is solved by a numerical
method. The final user selection and bandwidth allocation are obtained by
iteratively solving these two subproblems. Simulation results show that the
proposed FL algorithm that efficiently uses VLC and RF for FL model
transmission can improve the prediction accuracy by up to 10% compared with a
conventional FL system using only RF.Comment: WCNC202
Spatio-Temporal Patterns and Climate Variables Controlling of Biomass Carbon Stock of Global Grassland Ecosystems from 1982 to 2006
Grassland ecosystems play an important role in subsistence agriculture and the global carbon cycle. However, the global spatio-temporal patterns and environmental controls of grassland biomass are not well quantified and understood. The goal of this study was to estimate the spatial and temporal patterns of the global grassland biomass and analyze their driving forces using field measurements, Normalized Difference Vegetation Index (NDVI) time series from satellite data, climate reanalysis data, and a satellite-based statistical model. Results showed that the NDVI-based biomass carbon model developed from this study explained 60% of the variance across 38 sites globally. The global carbon stock in grassland aboveground live biomass was 1.05 Pg·C, averaged from 1982 to 2006, and increased at a rate of 2.43 Tg·C·yâ1 during this period. Temporal change of the global biomass was significantly and positively correlated with temperature and precipitation. The distribution of biomass carbon density followed the precipitation gradient. The dynamics of regional grassland biomass showed various trends largely determined by regional climate variability, disturbances, and management practices (such as grazing for meat production). The methods and results from this study can be used to monitor the dynamics of grassland aboveground biomass and evaluate grassland susceptibility to climate variability and change, disturbances, and management
Designer Amphiphilic Short Peptides Enhance Thermal Stability of Isolated Photosystem-I
Stability of membrane protein is crucial during protein purification and crystallization as well as in the fabrication of protein-based devices. Several recent studies have examined how various surfactants can stabilize membrane proteins out of their native membrane environment. However, there is still no single surfactant that can be universally employed for all membrane proteins. Because of the lack of knowledge on the interaction between surfactants and membrane proteins, the choice of a surfactant for a specific membrane protein remains purely empirical. Here we report that a group of short amphiphilic peptides improve the thermal stability of the multi-domain protein complex photosystem-I (PS-I) in aqueous solution and that the peptide surfactants have obvious advantages over other commonly used alkyl chain based surfactants. Of all the short peptides studied, Ac-I5K2-CONH2 (I5K2) showed the best stabilizing effect by enhancing the melting temperature of PS-I from 48.0°C to 53.0°C at concentration of 0.65 mM and extending the half life of isolated PS-I significantly. AFM experiments showed that PS-I/I5K2/Triton X-100 formed large and stable vesicles and thus provide interfacial environment mimicking that of native membranes, which may partly explain why I5K2 enhanced the thermal stability of PS-I. Hydrophobic and hydrophilic group length of IxKy had an important influence on the stabilization of PS-I. Our results showed that longer hydrophobic group was more effective in stabilizing PS-I. These simple short peptides therefore exhibit significant potential for applications in membrane protein studies
Federated Learning for 6G: Applications, Challenges, and Opportunities
Traditional machine learning is centralized in the cloud (data centers).
Recently, the security concern and the availability of abundant data and
computation resources in wireless networks are pushing the deployment of
learning algorithms towards the network edge. This has led to the emergence of
a fast growing area, called federated learning (FL), which integrates two
originally decoupled areas: wireless communication and machine learning. In
this paper, we provide a comprehensive study on the applications of FL for
sixth generation (6G) wireless networks. First, we discuss the key requirements
in applying FL for wireless communications. Then, we focus on the motivating
application of FL for wireless communications. We identify the main problems,
challenges, and provide a comprehensive treatment of implementing FL techniques
for wireless communications
Situational Analysis from Two Studies Facilitating the Development of a Psycho- Cultural Rehabilitation Program for Children Affected by the 12 May 2008 Earthquake in Sichuan, China
The data presented are from two field studies: (1) a survey of 2234 current childrenâs caregivers; and (2) interviews with 1200 children, evaluating the childrenâs social, psychological and behavioural situation after the devastating Sichuan earthquake in the hard-hit Qiang ethnic community. Insights from the findings will be used to develop an evidence-based, culturally appropriate approach on the best use of cultural resources to facilitate the childrenâs post-disaster rehabilitation. Evidence from the first study indicated that the disaster had a significant impact on the ethnic Qiang children and their families in regard to personal loss, physical injury, social relationships and psychological well-being. Evidence from the second study further indicated: (1) the need for a sustained response to the increasing vulnerability of these children; (2) a very limited effect from outside community visitors, whose one-off inconsistent, non-indigenous approaches and psychological counselling, drawing on the western, individualistic, approach to counseling and psychological/ psychiatric therapies and non-Qiang approaches do not carry over into the childrenâs everyday life in their own contexts; (3) that little is known about psycho-cultural factors as key resources for supporting an effective response to disaster for ethnic Qiang children; (4) the greatest need for a sustainable effect is therefore to build a culturally appropriate approach through making best use of cultural resources drawing on contributions of both volunteers and official workers from various disciplines and using the Qiang traditional ways to promote the childrenâs psycho-cultural rehabilitation
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