Distributed Multiagent Resource Allocation using Reservations to Improve Handling of Dynamic Task Arrivals

In the artificial intelligence subfield of multi-agent systems, there are many applications for algorithms which optimally allocate a set of resources among many available tasks which demand those resources. In this thesis we present a distributed algorithm to solve this problem which adapts well to dynamic task arrivals, where new work arises at short notice. This algorithm builds on prior work which focused on finding the optimal allocation in a closed environment with a fixed number of tasks. Our algorithm is designed to leverage preemption if it is available, revoking resource allocations to tasks in progress if new opportunities arise which those resources are better suited to handle. However, interrupting tasks in progress is rarely without cost, and our algorithm both respects these costs and may reserve resources to avoid unnecessary costs from hasty allocation. Our multi-agent model assigns a task agent to each task which must be completed and a proxy agent to each resource which is available. These proxy agents are responsible for allocating the resource they manage, while task agents are responsible for learning about their environment and planning out which resources to request for their task. The distributed nature of our model makes it easy to dynamically introduce new tasks with associated task agents. Preemption occurs when a task agent approaches a proxy agent with a sufficiently compelling need that the proxy agent determines the newcomer derives more benefit from the proxy agent's resource than the task agent currently using that resource. We compare to other multi-agent resource allocation frameworks which permit preemption under more conservative assumptions, and show through simulation that our planning and learning techniques allow for improved allocations through more permissive preemption. Our simulations present a medical application which models fallible human resources, though the techniques used are applicable to other domains such as computer scheduling. We then revisit the model with a focus on opportunity cost, introducing resource reservation as an alternative method to preemption for addressing expected future changes in the task allocation environment. Simulations help identify the scenarios where opportunity cost is a significant concern. The model is then further expanded to account for switching costs, where interrupting tasks in progress is worse than simply delaying tasks, and the logical extreme where resource allocation is irrevocable thus encouraging careful decisions about where to commit resources. This thesis makes three primary contributions to multi-agent resource allocation. The first is an improved distributed resource allocation framework which uses Transfer-of-Control strategies and learning to rapidly find good allocations in a dynamic environment. The second is a discussion of the importance of opportunity cost in resource allocation, accompanied by a simple "dummy agent" implementation which validates the use of resource reservation to address scenarios vulnerable to opportunity cost. Finally, the effectiveness of this resource allocation framework with reservation is extended to environments where preemption is costly or impossible

The Emperor Moths of Eastern Africa

Volume: XXII

Predictors of Breast and Cervical Cancer Screening among Chamorro Women in Southern California

This study examined the role of sociodemographic characteristics, health insurance, cancer knowledge, perceived health risk, and having a recent physicians’ visit on breast and cervical cancer screening utilization among a randomly selected group of Chamorro women (n = 250) residing in San Diego, California. Data were collected by a telephone survey and analyzed using multiple logistic regression models. After adjusting for covariates, having a recent full exam was the strongest predictor of having had a Pap exam in the past 2 years for women 21 years and older and a clinical breast exam in the past 2 years for women 40 years and over

Palaeozoic giant dragonfies were hawker predators

The largest insects to have ever lived were the giant meganeurids of the Late Palaeozoic, ancient stem relatives of our modern dragonfies. With wingspans up to 71cm, these iconic insects have been the subject of varied documentaries on Palaeozoic life, depicting them as patrolling for prey through coal swamp forests amid giant lycopsids, and cordaites. Such reconstructions are speculative as few defnitive details of giant dragonfy biology are known. Most specimens of giant dragonfies are known from wings or isolated elements, but Meganeurites gracilipes preserves critical body structures, most notably those of the head. Here we show that it is unlikely it thrived in densely forested environments where its elongate wings would have become easily damaged. Instead, the species lived in more open habitats and possessed greatly enlarged compound eyes. These were dorsally hypertrophied, a specialization for long-distance vision above the animal in fight, a trait convergent with modern hawker dragonfies. Sturdy mandibles with acute teeth, strong spines on tibiae and tarsi, and a pronounced thoracic skewness are identical to those specializations used by dragonfies in capturing prey while in fight. The Palaeozoic Odonatoptera thus exhibited considerable morphological specializations associated with behaviours attributable to ‘hawkers’ or ‘perchers’ among extant Odonata.This work benefted from a grant of the French ‘Agence Nationale de la Recherche’ via the program ‘Investissements d’avenir’ (ANR-11-INBS-0004-RECOLNAT)JP and MP gratefully acknowledge research support from the Grant Agency of the Czech Republic No. 18-03118 SThe work of MSE was supported by US National Science Foundation grant DEB-114416

Cardiovascular risk factors among Chamorros

BACKGROUND: Little is known regarding the cardiovascular disease risk factors among Chamorros residing in the United States. METHODS: The Chamorro Directory International and the CDC's Behavioral Risk Factor Surveillance System Questionnaire (BRFSS) were used to assess the health related practices and needs of a random sample of 228 Chamorros. RESULTS: Inactivity, hypertension, elevated cholesterol and diabetes mellitus were more prevalent in this Chamorro sample compared to the US average. Participants who were 50-and-older or unemployed were more likely to report hypertension, diabetes and inactivity, but they were also more likely to consume more fruits and vegetables than their younger and employed counterparts. Women were more likely to report hypertension and diabetes, whereas men were more likely to have elevated BMI and to have never had their blood cholesterol checked. CONCLUSION: The study provides data that will help healthcare providers, public health workers and community leaders identify where to focus their health improvement efforts for Chamorros and create culturally competent programs to promote health in this community

Health Indicators of Native Hawaiian and Pacific Islanders in the United States

This study aimed to describe health indicators and behaviors of Native Hawaiian and Pacific Islander (NHPI) adults and to compare findings to previous reports on US NHPI and the US population. A sample of N = 100 (56 M, 44 F) NHPI adults aged 40–59 years completed an anonymous questionnaire addressing education and household income, tobacco use, physical activity, fruit and vegetable (F&V) consumption, cancer screening and health status. Objective measures of height and weight were taken to calculate body mass index (BMI). The study sample consisted of 49% current smokers and the majority was not meeting guidelines for physical activity (80%) or F&V consumption (99%). Cancer screening rates ranged from 0 to 57% and were higher among females. Mean BMI was 33.9 ± 7.5 kg/m2 and 95% were overweight or obese. While 36.7% were hypertensive, only 11.1% were taking prescribed medication. Compared to both the general US population and available data for US NHPI, study participants reported higher prevalence of obesity and chronic conditions (hypertension, high cholesterol, diabetes, and angina/CHD) and lower levels of physical activity, F&V consumption and cancer screening rates. Study findings contribute to the limited knowledge regarding health behaviors of US NHPI. Comparisons to US data increase evidence of NHPI health disparities, while comparisons to previous NHPI studies emphasize the magnitude of unhealthy lifestyle behaviors and subsequent adverse health conditions for this particular sample. Further improvements to community outreach and recruitment strategies could successfully encourage high-risk individuals to participate in health promotion and behavior intervention studies to improve NHPI health behaviors