Vehicular ad hoc network (VANET) is an emerging type of networks which facilitates vehicles on roads to communicate for driving safety. The basic idea is to allow arbitrary vehicles to broadcast ad hoc messages (e.g. traffic accidents) to other vehicles. However, this raises the concern of security and privacy. Messages should be signed and verified before they are trusted while the real identity of vehicles should not be revealed, but traceable by authorized party. Existing solutions either rely heavily on a tamper-proof hardware device, or cannot satisfy the privacy requirement and do not have an effective message verification scheme. In this paper, we provide a software-based solution which makes use of only two shared secrets to satisfy the privacy requirement (with security analysis) and gives lower message overhead and at least 45% higher successful rate than previous solutions in the message verification phase using the bloom filter and the binary search techniques (through simulation study). We also provide the first group communication protocol to allow vehicles to authenticate and securely communicate with others in a group of known vehicles.

This paper describes an algorithm for constructing a single hidden layer feedforward neural network. A distinguishing feature of this algorithm is that it uses the quasi-Newton method to minimize the sequence of error functions associated with the growing network. Experimental results indicate that the algorithm is very efficient and robust. The algorithm was tested on two test problems. The first was the n-bit parity problem and the second was the breast cancer diagnosis problem from the University of Wisconsin Hospitals. For the n-bit parity problem, the algorithm was able to construct neural network having less than n hidden units that solved the problem for n=4,...,7. For the cancer diagnosis problem, the neural networks constructed by the algorithm had small number of hidden units and high accuracy rates on both the training data and the testing data.

To investigate the association between birth weight, infant growth rate, and childhood adiposity as a proxy for adult metabolic or cardiovascular risk in a Chinese population with a history of recent and rapid economic development.

OBJECTIVE: To identify risk factors for overweight in Hong Kong children aged 6-7 y. DESIGN: Case-control study. SETTING: Student Health Service Centres, Hong Kong. SUBJECTS: A total of 343 Hong Kong Chinese children aged 6-7 y old categorised into three groups, an overweight group (Z92nd centile for BMI), a normal middle-weight group (45th-55th centile for BMI) and a normal low-weight group (r8th centile for BMI). MEASUREMENTS: Subjects and their parents/caregivers were interviewed at home. Data on lifestyle habits, dietary habits, family structure and demographic background were collected by questionnaire. A 3-day dietary record was administrated by the parents/caregivers to assess dietary intake of the children. RESULTS: Logistic regression analyses (overweight group compared with middle-weight plus low-weight groups) showed that childhood overweight was significantly associated with parental obesity (BMI Z25 kg/m 2 , Asian reference) (paternal: OR ¼ 2.66, 95% CI ¼ 1.51-4.70; maternal: 5.07, 2.62-9.79) but not parental overweight (BMI ¼ 23-25 kg/m 2 ). After adjustment for parental obesity, the odds ratio for childhood overweight was increased by birth weight (o3.0 kg as reference, 3.0-3.5 kg: 2.13, 1.18-3.84; Z3.5 kg: 4.89, 2.49-9.60) and decreased by sleeping duration (o9 h/day as reference, 9-11 h/day: 0.54, 0.30-0.97; Z11 h/day: 0.31, 0.11-0.87). Childhood overweight was also significantly associated with higher energy consumption (2.62, 1.20-5.74) and having a father who was a current smoker (2.08, 1.25-3.46). CONCLUSIONS: Although healthy diet and regular exercise will remain the cornerstones of obesity management in children, our data support the view that education about maintaining a healthy weight could be introduced much earlier in those families with high-risk children, as indicated by high parental BMI or high birth weight. The utility and practicality of such an approach should be carefully evaluated before becoming part of any public health policy. Further study of the role of short sleeping duration and parental smoking on childhood obesity development is warranted.

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In this paper, we propose a navigation scheme that utilizes the online road information collected by a vehicular ad hoc network (VANET) to guide the drivers to desired destinations in a real-time and distributed manner. The proposed scheme has the advantage of using real-time road conditions to compute a better route and at the same time, the information source can be properly authenticated. To protect the privacy of the drivers, the query (destination) and the driver who issues the query are guaranteed to be unlinkable to any party including the trusted authority. We make use of the idea of anonymous credential to achieve this goal. In addition to authentication and privacy-preserving, our scheme fulfills all other necessary security requirements. Using the real maps of New York and California, we conducted a simulation study on our scheme showing that it is effective in terms of processing delay and providing routes of much shorter travelling time.

Vehicular ad hoc network (VANET) is an emerging type of networks which facilitates vehicles on roads to communicate for driving safety. The basic idea is to allow arbitrary vehicles to broadcast ad hoc messages (e.g. traffic accidents) to other vehicles. However, this raises the concern of security and privacy. Messages should be signed and verified before they are trusted while the real identity of vehicles should not be revealed, but traceable by authorized party. Existing solutions either rely heavily on a tamper-proof hardware device, or cannot satisfy the privacy requirement and do not have an effective message verification scheme. In this paper, we provide a software-based solution which makes use of only two shared secrets to satisfy the privacy requirement (with security analysis) and gives lower message overhead and at least 45% higher successful rate than previous solutions in the message verification phase using the bloom filter and the binary search techniques (through simulation study). We also provide the first group communication protocol to allow vehicles to authenticate and securely communicate with others in a group of known vehicles.

No abstract