Message and time efficient multi-broadcast schemes

We consider message and time efficient broadcasting and multi-broadcasting in wireless ad-hoc networks, where a subset of nodes, each with a unique rumor, wish to broadcast their rumors to all destinations while minimizing the total number of transmissions and total time until all rumors arrive to their destination. Under centralized settings, we introduce a novel approximation algorithm that provides almost optimal results with respect to the number of transmissions and total time, separately. Later on, we show how to efficiently implement this algorithm under distributed settings, where the nodes have only local information about their surroundings. In addition, we show multiple approximation techniques based on the network collision detection capabilities and explain how to calibrate the algorithms' parameters to produce optimal results for time and messages.Comment: In Proceedings FOMC 2013, arXiv:1310.459

The Curatorial Muse

An appreciation of the tension between the predicate, to curate, and the subject, the curator, is essential to understanding the convergence of creation, criticism, and administration in the graphic arts of our time. Curators were ideally positioned to step to the fore when the idea-versus-object dichotomy began to collapse in the work of Duchamp. The roots of activist curating can be found in Western Classical culture. The prevalence of conceptual art at the end of the twentieth century, combined with the explicit denigration of physical craft by artists, created a void into which activist curators moved. The curator\u27s role as educator and referee in artistic style wars needs to be reexamined in light of contemporary analyses of the nature of power. Our understanding of the nexus of art-making, criticism, and curating is profoundly compromised by our skill in suppressing the many pious fictions upon which these activities are founded

Creating View-dependent Texture Maps

We present a technique for blending multiple images of an object into a single, view-dependent texture map for that object. This technique can be used for image-based rendering, when the object is known, or for “painting” a view-dependent texture map of an object. The technique provides a structured mechanism for combing images at different resolutions, producing a mip-map like structure with the different levels constructed from different images. The user controls the camera angles for which a given image is valid. The technique is also suitable for use on an object that will be animated

A simple model of ocean temperature re-emergence and variability

A simple stochastic one-dimensional model of interannual mid-latitude sea surface temperature (SST) variability that can be solved analytically is developed. A novel two-season approach is adopted, with the annual cycle divided into two seasons denoted summer and winter. Within each season the mixed layer depth is constant, and the transition of the mixed layer from summer to winter and vice versa is discontinuous. SST anomalies are forced by random atmospheric heat fluxes, assumed to be constant within each season for simplicity, with linear damping to represent atmospheric feedback. At the start of summer the initial SST anomaly is set equal to that at the end of the previous winter, and at the start of winter the initial temperature anomaly is found by instantaneously mixing the summer mixed layer with the heat stored below in the deeper winter mixed layer, thereby explicitly taking into account the ‘re-emergence mechanism’. Two simple auto-regressive equations for the summer and winter SST anomalies are obtained that can be easily solved. Model parameters include seasonal damping coefficients, mixed layer depths and standard deviations of the atmospheric forcing. Analytic expressions for season-to-season correlation and variability and power spectra are used to explore and illustrate the effects of the parameters quantitatively. Among the results it is found that, with regard to winter-to-winter temperature correlation, the re-emergence pathway is more influential than persistence via the summer mixed layer when the winter layer is more than twice the depth of the summer layer. With regard to winter temperature variability, the effect of a deeper winter mixed layer is to decrease the sensitivity to surface forcing and thus decrease variability, but also to increase persistence via re-emergence and thus increase variance at multidecadal scales

Stimulating a Great Lakes Coastal Wetland Seed Bank using Portable Cofferdams: Implications for Habitat Rehabilitation

Coastal wetland seed banks exposed by low lake levels or through management actions fuel the reestablishment of emergent plant assemblages (i.e., wetland habitat) critical to Great Lakes aquatic biota. This project explored the effectiveness of using portable, water-filled cofferdams as a management tool to promote the natural growth of emergent vegetation from the seed bank in a Lake Erie coastal wetland. A series of dams stretching approximately 450 m was installed temporarily to isolate hydrologically a 10-ha corner of the Crane Creek wetland complex from Lake Erie. The test area was dewatered in 2004 to mimic a low-water year, and vegetation sampling characterized the wetland seed bank response at low, middle, and high elevations in areas open to and protected from bird and mammal herbivory. The nearly two-month drawdown stimulated a rapid seed-bank-driven response by 45 plant taxa. Herbivory had little effect on plant species richness, regardless of the location along an elevation gradient. Inundation contributed to the replacement of immature emergent plant species with submersed aquatic species after the dams failed and were removed prematurely. This study revealed a number of important issues that must be considered for effective long-term implementation of portable cofferdam technology to stimulate wetland seed banks, including duration of dewatering, product size, source of clean water, replacement of damaged dams, and regular maintenance. This technology is a potentially important tool in the arsenal used by resource managers seeking to rehabilitate the functions and values of Great Lakes coastal wetland habitats

Fish Assemblages, Connectivity, and Habitat Rehabilitation in a Diked Great Lakes Coastal Wetland Complex

Fish and plant assemblages in the highly modified Crane Creek coastal wetland complex of Lake Erie were sampled to characterize their spatial and seasonal patterns and to examine the implications of the hydrologic connection of diked wetland units to Lake Erie. Fyke netting captured 52 species and an abundance of fish in the Lake Erie–connected wetlands, but fewer than half of those species and much lower numbers and total masses of fish were captured in diked wetland units. Although all wetland units were immediately adjacent to Lake Erie, there were also pronounced differences in water quality and wetland vegetation between the hydrologically isolated and lake-connected wetlands. Large seasonal variations in fish assemblage composition and biomass were observed in connected wetland units but not in disconnected units. Reestablishment of hydrologic connectivity in diked wetland units would allow coastal Lake Erie fish to use these vegetated habitats seasonally, although connectivity does appear to pose some risks, such as the expansion of invasive plants and localized reductions in water quality. Periodic isolation and drawdown of the diked units could still be used to mimic intermediate levels of disturbance and manage invasive wetland vegetation

Comparative study of oscillatory integral, and sub-level set, operator norm estimates

Oscillatory integral operators have been of interest to both mathematicians and physicists ever since the emergence of the work Theorie Analytique de la Chaleur of Joseph Fourier in 1822, in which his chief concern was to give a mathematical account of the diffusion of heat. For example, oscillatory integrals naturally arise when one studies the behaviour at infinity of the Fourier transform of a Borel measure that is supported on a certain hypersurface. One reduces the study of such a problem to that of having to obtain estimates on oscillatory integrals. However, sub-level set operators have only come to the fore at the end of the 20th Century, where it has been discovered that the decay rates of the oscillatory integral I(lambda) above may be obtainable once the measure of the associated sub-level sets are known. This discovery has been fully developed in a paper of A. Carbery, M. Christ and J.Wright. A principal goal of this thesis is to explore certain uniformity issues arising in the study of sub-level set estimates

Victimization Prior to Jail: The Effect of Physical and/or Sexual Victimization on Mental Health and Substance Use Disorder in a Population of Jailed Inmates

Previous research shows a link between abuse histories and negative outcomes, including a relationship between abuse victimization and mental illness and/or substance use disorder and between such victimization and criminal behavior. The relationship between abuse and offending or reoffending is likely indirect, working by way of mental illness and/or substance use disorder. However, the effects of these abuse experiences prior to incarceration as well as the impact of abuse perpetrator type and abuse timing on mental health and substance use outcomes have been underexplored in jail populations. The current analysis addresses this gap. From February 21st, 2017 to September 12th, 2017, people admitted to jail were screened by intake staff, and these assessments supplemented administrative admissions data. Assessments included 79 questions developed by jail administrators and a research team of faculty research partners. A total of 4,713 individuals were admitted to the jail, including people detained for pretrial purposes and those convicted and sentenced to jail. The majority of the population (72.3%) reported no history of abuse, but 17.5% indicated a history of physical abuse, 3.2% a history of sexual abuse, and 10.0% a history of polyvictimization (both physical and sexual abuse). Further, 43.6% of jailed individuals had a high level of an internalizing disorder while 19.4% had a high level of an externalizing disorder. Lastly, 28.5% of the population had a substance use disorder. We found evidence to suggest that a history of physical abuse has similar effects for men and women on the likelihood of internalizing disorders but that a history of sexual abuse had a larger influence on women. Polyvictimization also predicted internalizing disorders for men and women. Similarly, a history of physical abuse resulted in greater odds of externalizing disorders across sex, but a history of sexual abuse significantly predicted externalizing disorders for women only. In contrast, polyvictimization predicted greater odds of externalizing disorders for men. A history of victimization was largely unrelated to substance use disorder with the exception of polyvictimization reported by men. Regarding the perpetrator of abuse, the strongest effect was found for perpetration by a non-stranger, resulting in greater odds of internalizing disorders (all abuse types) and externalizing disorders (only physical abuse and polyvictimization). A history of victimization by either a non-stranger or stranger was largely unrelated to substance use disorder. For abuse timing, the strongest effects were found for abuse experienced prior to age 18 for internalizing and externalizing disorders. Timing of abuse was largely unrelated to substance use disorder as an outcome. Finally, across analyses, substance use disorder was significantly related to internalizing and externalizing disorders and vice versa. Taken together, we found that a history of physical and/or sexual abuse were significantly associated with mental health outcomes across men and women in jail whereas past research has focused primarily on the link between abuse, mental illness, substance use, and offending/reoffending amongst women. However, a history of abuse was largely unassociated with substance use disorder as an outcome, which is counter to past research in justice-involved youth and people incarcerated in prisons. Instead, our findings suggest that, rather than being an intervening variable between abuse histories and criminal behavior, which appears to be the case for internalizing and externalizing disorders in our study, substance use disorder may not act as an indirect pathway between abuse and offending but may still affect criminal behavior by way of mental illness or vice versa