The Determinants of Perceived Health and Labour Force Participation of People with HIV/AIDS in Khayelitsha, South Africa

This paper examines the impact of Highly Active Antiretroviral Treatment (HAART) on perceived health and labour force participation of people living with HIV/AIDS in Khayelitsha, South Africa. Cox Proportional Hazard Models with stratum effects for three medical clinics, and Accelerated Failure Time Models with individual specific unobserved shared effects (frailty), are estimated for transitions to improved perceptions of health, and transition in and out of the labour market, using a longitudinal data set. We find that HAART has a positive impact on perceived health, and restored health leads to greater activity in the labour market

Climbing Career Steps: Becoming a Full Professor of Economics

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73124/1/1467-9442.00075.pd

Packet arrival analysis in wireless sensor networks

Distributed sensor networks have been discussed for more than 30 years, but the vision of Wireless Sensor Networks (WSNs) has been brought into reality only by the rapid advancements in the areas of sensor design, information technologies, and wireless networks that have paved the way for the proliferation of WSNs. The unique characteristics of sensor networks introduce new challenges, amongst which prolonging the sensor lifetime is the most important. WSNs have seen a tremendous growth in various application areas including health care, environmental monitoring, security, and military purposes despite prominent performance and availability challenges. Clustering plays an important role in enhancement of the life span and scalability of the network, in such applications. Although researchers continue to address these grand challenges, the type of distributions for arrivals at the cluster head and intermediary routing nodes is still an interesting area of investigation. Modelling the behaviour of the networks becomes essential for estimating the performance metrics and further lead to decisions for improving the network performance, hence highlighting the importance of identifying the type of inter-arrival distributions at the cluster head. In this paper, we present extensive discussions on the assumptions of exponential distributions in WSNs, and present numerical results based on Q-Q plots for estimating the arrival distributions. The work is further extended to understand the impact of end-to-end delay and its effect on inter-arrival time distributions, based on the type of medium access control used in WSNs. Future work is also presented on the grounds that such comparisons based on simple eye checks are insufficient. Since in many cases such plots may lead to incorrect conclusions, demanding the necessity for validating the types of distributions. Statistical analysis is necessary to estimate and validate the empirical distributions of the arrivals in WSNs

Does the assumption of exponential arrival distributions in wireless sensor networks hold?

Wireless Sensor Networks have seen a tremendous growth in various application areas despite prominent performance and availability challenges. One of the common configurations to prolong the lifetime and deal with the path loss phenomena having a multi-hop set-up with clusters and cluster heads to relay the information. Although researchers continue to address these challenges, the type of distribution for arrivals at the cluster head and intermediary routing nodes is still an interesting area of investigation. The general practice in published works is to compare an empirical exponential arrival distribution of wireless sensor networks with a theoretical exponential distribution in a Q-Q plot diagram. In this paper, we show that such comparisons based on simple eye checks are not sufficient since, in many cases, incorrect conclusions may be drawn from such plots. After estimating the Maximum Likelihood parameters of empirical distributions, we generate theoretical distributions based on the estimated parameters. By conducting Kolmogorov-Smirnov Test Statistics for each generated inter-arrival time distributions, we find out, if it is possible to represent the traffic into the cluster head by using theoretical distribution. Empirical exponential arrival distribution assumption of wireless sensor networks holds only for a few cases. There are both theoretically known such as Gamma, Log-normal and Mixed Log-Normal of arrival distributions and theoretically unknown such as non-Exponential and Mixed cases of arrival in wireless sensor networks. The work is further extended to understand the effect of delay on inter-arrival time distributions based on the type of medium access control used in wireless sensor networks

Packet Arrival Analysis in Wireless Sensor Networks

Distributed sensor networks have been discussed for more than 30 years, but the vision of Wireless Sensor Networks (WSNs) has been brought into reality only by the rapid advancements in the areas of sensor design, information technologies, and wireless networks that have paved the way for the proliferation of WSNs. The unique characteristics of sensor networks introduce new challenges, amongst which prolonging the sensor lifetime is the most important. WSNs have seen a tremendous growth in various application areas including health care, environmental monitoring, security, and military purposes despite prominent performance and availability challenges. Clustering plays an important role in enhancement of the life span and scalability of the network, in such applications. Although researchers continue to address these grand challenges, the type of distributions for arrivals at the cluster head and intermediary routing nodes is still an interesting area of investigation. Modelling the behaviour of the networks becomes essential for estimating the performance metrics and further lead to decisions for improving the network performance, hence highlighting the importance of identifying the type of inter-arrival distributions at the cluster head. In this paper, we present extensive discussions on the assumptions of exponential distributions in WSNs, and present numerical results based on Q-Q plots for estimating the arrival distributions. The work is further extended to understand the impact of end-to-end delay and its effect on inter-arrival time distributions, based on the type of medium access control used in WSNs. Future work is also presented on the grounds that such comparisons based on simple eye checks are insufficient. Since in many cases such plots may lead to incorrect conclusions, demanding the necessity for validating the types of distributions. Statistical analysis is necessary to estimate and validate the empirical distributions of the arrivals in WSNs

The relation between arrangements for health and safety and injury rates: the evidence-based case revisited

This paper re-examines the most influential analysis of the relation between worker representation and industrial injuries in British manufacturing, the work of Reilly et al, which appeared in the British Journal of Industrial Relations 33 (3). It argues that although this has been misinterpreted by some who cite it, the reliability of its authors’ findings must also be questioned. A step by step replication of their analysis of WIRS90 data is reported, followed by a further examination of data for WERS98. In neither case are the specific claims advanced in the original analysis robust enough to survive scrutiny. Only the more general conclusion that health and safety should not be left to management is adequately supported

The emergence of a new generation of workers in Turkish industry: an examination of age related differences

This paper explores the possible effects of the increasing exposure to modernity on younger workers in some sectors of developing countries with special reference to those employed in advanced manufacturing in Turkey. In recent decades Turkey has undergone considerable urbanisation, improvements in literacy and rising levels of formal education. The paper systematically examines differences in the work-related attitudes and expectations, commitment and aspirations of younger and older workers, who have been exposed to these processes to different degrees. The hypothesis is broadly confirmed that younger workers have higher expectations and aspirations that make them relatively less satisfied with a number of aspects of their work and which are likely to make for a less committed more critical workforce