The wireless network jamming problem

In adversarial environments, disabling the communication capabilities of the enemy is a high priority. We introduce the problem of determining the optimal number and locations for a set of jamming devices in order to neutralize a wireless communication network. This problem is known as the wireless network jamming problem. We develop several mathematical programming formulations based on covering the communication nodes and limiting the connectivity index of the nodes. Two case studies are presented comparing the formulations with the addition of various percentile constraints. Finally, directions of further research are addressed.     

Implications of the 65-mph speed limit for traffic safety.

This study evaluates the impact of the 65-mph speed limit on traffic safety. Using data for the years 1981 to 1995 for all 50 states, a pooled time series analysis is conducted. Separate models are estimated for state fatality rates on four categories of roads: rural interstate highways, rural noninterstate roads, all roads except for rural interstate highways, and all roads. It is reported that the 65-mph speed limit increased fatality rates on rural interstate highways but was correlated with a reduction in state fatality rates on the three other categories of roads.     

PUBLIC WEALTH,PUBLIC HEALTH,AND PRIVATE STEALTH: EXAMINING THE BLACK MARKET IN CIGARETTES IN AUSTRALIA

Taxes on tobacco provide a significant income for the Australian government — $5.1 billion in 2001. At the same time, health officials are making strenuous efforts to reduce smoking, particularly among teenagers. Some economists suggest that raising taxes on tobacco will produce more revenue while at the same time lowering smoking rates, particularly among youths who have less discretionary spending power than adults. But a by‐product of excise tax in Australia has been the emerging market in “chop‐chop,” tobacco diverted from legal channels by growers who receive considerably higher prices for a part of their yield than they can obtain from legal manufacturers. The article details this situation and suggests that only bold solutions may be able to reduce tensions in tax policies, smoking rates and the “chop‐chop” black market.     

MILITIAS AT THE MILLENNIUM:

Critically important to Neil Smelser's theory of collective behavior is the idea that people join radical social movements because they experience strain. A social movement arises to reassure participants that something is being done to redress the underlying source of strain. Militia presence and activity on the Internet (especially Usenet) is a phenomenon that can be studied within Smelser's framework. Militia watchers contend that those who join the militias have experienced the kinds of strain to which Smelser refers. The purpose of this article is to analyze the content of Internet traffic of U.S. militias in order to test the thesis outlined above. It uses militia Web sites and militia messages posted to Usenet (N = 1,196) as primary data to test Smelser's theory. Information was gathered on 171 men and women from 28 U.S. militias who posted messages to Usenet from 1998–2001. Based on the militiamen/women studied, Smelser's thesis is generally confirmed. Most experienced some form of social stress or strain prior to or during the time that they were in the militia, and most conditions for social movement development as specified by Smelser were met and confirmed by the data.     

Estimating the completeness of under-5 death registration in Egypt

To evaluate the completeness of registration of infant and child deaths in Egypt, reinterviews were conducted with families who had reported a death of a child under age 5 in the five years before the survey for two national surveys recently conducted in Egypt: the United Nations PAPCHILD survey of1990-1991 and the Egyptian Demographic and Health Survey (EDHS) of 1992. The survey instrument included questions regarding notification of the death at the local health bureau. If the family said the death had been notified, separate employees searched the health bureau records for the registration. Overall 57% of infant deaths were reported as notified and 68% of those death reports were found; the corresponding figuresfor child deaths were 89% and 74%. Using the percentage reported as notified as an estimate for completeness of registration, we adjusted upward the national infant and child mortality rates from registration data, giving values of 73 per 1,000 for infant mortality and 99 for ₅q₀ for the period 1987-1990. These values are approximately 20% above the corresponding direct estimates from the PAPCHILD and EDHS surveys.     

Word Learning in Children Following Cochlear Implantation

An experimental procedure was developed to investigate word-learning skills of children who use cochlear implants (CIs). Using interactive play scenarios, 2- to 5-year olds were presented with sets of objects (Beanie Baby stuffed animals) and words for their names that corresponded to salient perceptual attributes (e.g., "horns" for a goat). Their knowledge of the word-object associations was measured immediately after exposure and then following a 2-hour delay. Children who use cochlear implants performed more poorly than age-matched children with typical hearing both receptively and expressively. Both groups of children showed retention of the word-object associations in the delayed testing conditions for words that were previously known. Our findings suggest that although pediatric CI users may have impaired phonological processing skills, their long-term memory for familiar words may be similar to children with typical hearing. Further, the methods that developed in this study should be useful for investigating other aspects of word learning in children who use CIs.     

From Hospital to Home with NDIS Funded Support: Examining Participant Pathway Timeframes Against Discharge Expectations

ABSTRACT

For patients with disability who require funded supports to leave hospital, the introduction of the National Disability Insurance Scheme (NDIS) represents opportunity and challenges. At a time of major reform, timely and supported discharge is reliant on overcoming interface complexities. The purpose of this study was to examine the NDIS participant pathway timeframes against discharge expectations for hospitalised adults with spinal cord injury (SCI) or acquired brain injury (ABI) and interrogate delays for the two groups. Administrative data on 54 participants (ABI?=?18 and SCI?=?36) were analysed. Both groups experienced delays to discharge and significant variability in timeframes between NDIS pathway processes and extent of delays. Group differences were identified regarding inefficiencies across the continuum, with type of support a factor to investigate further. This study has uncovered critical points in the NDIS pathway that could impact discharge of participants and where collaboration and adaptive strategies could be targeted to improve processes.

IMPLICATIONS

• Ensuring the National Disability Insurance Scheme (NDIS) pathway operates effectively in the hospital setting is critical to the timely discharge of people with complex needs who require funded supports.

• Monitoring implementation of the NDIS in the health setting is important to avert interface problems that impede timely discharge and access.