Providing Long-Term Participation Incentive in Participatory Sensing

Providing an adequate long-term participation incentive is important for a participatory sensing system to maintain enough number of active users (sensors), so as to collect a sufficient number of data samples and support a desired level of service quality. In this work, we consider the sensor selection problem in a general time-dependent and location-aware participatory sensing system, taking the long-term user participation incentive into explicit consideration. We study the problem systematically under different information scenarios, regarding both future information and current information (realization). In particular, we propose a Lyapunov-based VCG auction policy for the on-line sensor selection, which converges asymptotically to the optimal off-line benchmark performance, even with no future information and under (current) information asymmetry. Extensive numerical results show that our proposed policy outperforms the state-of-art policies in the literature, in terms of both user participation (e.g., reducing the user dropping probability by 25% to 90%) and social performance (e.g., increasing the social welfare by 15% to 80%).Comment: This manuscript serves as the online technical report of the article published in IEEE International Conference on Computer Communications (INFOCOM), 201

Understanding Child Support Trends: Economic, Demographic, and Political Contributions

We use data from the Panel Study of Income Dynamics (PSID) to examine trends in child support payments over the past thirty years and to assess five different explanations for these trends: inflation, the shift to unilateral divorce, changes in marital status composition, changes in men's and women's earnings, and ineffective child support laws. We find that during the 1970s and early 1980s, three factors high inflation, increase in non-marital childbearing, and shifts to unilateral divorse--exerted downward pressure on child support payments. Throughout this time period, child support policies were weak, and average real payments declined sharply. Our findings indicate that two child support policies legislative guidelines for awards and universal wage withholding--are important for insuring child support payments. Finally, our analyses suggest that further gains in child support payments will rest with our ability to collect child support for children born to unwed parents. These children are the fastest growing group of children in the US, and they are the least likely to receive child support. To date, child support policies have been ineffective in assuring child support for never married mothers.

How Hungry is the Selfish Gene?

We examine resource allocation in step-households, in the United States and South Africa, to test whether child investments vary according to economic and genetic bonds between parent and child. We used 18 years of data from the Panel Study of Income Dynamics, and compare food expenditure by family type, holding constant household size, age composition and income. We find that in those households in which a child is raised by an adoptive, step or foster mother, less is spent on food. We cannot reject the hypothesis that the effect of replacing a biological child with a non- biological child is the same, whether the non-biological child is an adoptive, step or foster child of the mother. In South Africa, where we can disaggregate food consumption more finely, we find that when a child's biological mother is the head or spouse of the head of household, the household spends significantly more on food, in particular on milk and fruit and vegetables, and significantly less on tobacco and alcohol. The genetic tie to the child, and not any anticipated future economic tie, appears to be the tie that binds.

BURROWING AND WALKING MECHANISMS OF NORTH AMERICAN MOLES

Moles (Family Talpidae) are a classic example of extreme specialization, in their case highly derived forelimb morphologies associated with burrowing. Despite many observations of mole burrows and behaviors gathered in the field, we know very little about how and how well moles use their forelimbs to dig tunnels and to walk within the built tunnels to collect and transport food. The first chapter investigates the effect of soil compactness on two sympatric mole species under controlled laboratory conditions. My results demonstrate that increasing soil compactness impedes tunneling performance as evidenced by reduced burrowing speed, increased soil transport, shorter tunnels, shorter activity time, and less time spent burrowing continuously. Furthermore, differences in performance between the two mole species may be associated with differences in the structure and extent of their burrow systems or the morphology of their forelimbs. The second chapter investigates the kinematics of Eastern moles burrowing in loose and compact substrates. Using XROMM (X-ray Reconstruction of Moving Morphology), I found that moles move substrate dorsally using elevating strokes in loose substrates and laterally using scratching strokes in compact substrates. They do not move the substrate caudally like most mammalian forelimb diggers. Furthermore, my results demonstrate that the combination of stereotypic movements of the shoulder joint, where the largest digging muscles are located, and flexibility in elbow and wrist joints makes moles extremely effective diggers in both loose and compact substrates. In the third chapter I test two hypotheses about forelimb movements during walking. The first is that moles move their shoulders by humeral long-axis rotation, as they do during burrowing and in walking echidnas. The second is that moles move their shoulders by flexion and extension in the horizontal plane, similar to sprawling reptiles. Surprisingly, my results reject both hypotheses and indicate that the way moles walk is different from that of all tetrapods that have been studied. The results of my dissertation open new horizons in the study of morphological, physiological, behavioral and ecological evolution of fossoriality, and may provide new ideas for the design of bio-inspired robots used for urban search and rescue

Mitochondrial redox signaling by p66Shc is involved in regulating androgenic growth stimulation of human prostate cancer cells.

p66Shc is shown to negatively regulate the life span in mice through reactive oxygen species (ROS) production. Recent reports, however, revealed that p66Shc protein level is significantly elevated in several human cancer tissues and growth-stimulated carcinoma cells, suggesting a mitogenic and carcinogenic role for p66Shc. In this communication, we demonstrate for the first time that p66Shc mediates androgenic growth signals in androgen-sensitive human prostate cancer cells through mitochondrial ROS production. Growth stimulation of prostate cancer cells with 5alpha-dihydrotestosterone (DHT) is accompanied by increased p66Shc level and ROS production, which is abolished by antioxidant treatments. However, antioxidant treatments do not affect the transcriptional activity of androgen receptor (AR) as observed by its inability to block DHT-induced prostate-specific antigen expression, an AR-dependent correlate of prostate cancer progression. Elevated expression of p66Shc by cDNA transfection increases the basal cell proliferation and, thus, reduces additional DHT-induced cell proliferation. Furthermore, DHT increases the translocation of p66Shc into mitochondria and its interaction with cytochrome c. Conversely, both redox-negative p66Shc mutant (W134F), which is deficient in cytochrome c interaction, and p66Shc small interfering RNA decrease DHT-induced cell proliferation. These results collectively reveal a novel role for p66Shc-ROS pathway in androgen-induced prostate cancer cell proliferation and, thus, may play a role in early prostate carcinogenesis