On the Tree Conjecture for the Network Creation Game

Selfish Network Creation focuses on modeling real world networks from a game-theoretic point of view. One of the classic models by Fabrikant et al.[PODC\u2703] is the network creation game, where agents correspond to nodes in a network which buy incident edges for the price of alpha per edge to minimize their total distance to all other nodes. The model is well-studied but still has intriguing open problems. The most famous conjectures state that the price of anarchy is constant for all alpha and that for alpha >= n all equilibrium networks are trees. We introduce a novel technique for analyzing stable networks for high edge-price alpha and employ it to improve on the best known bounds for both conjectures. In particular we show that for alpha > 4n-13 all equilibrium networks must be trees, which implies a constant price of anarchy for this range of alpha. Moreover, we also improve the constant upper bound on the price of anarchy for equilibrium trees

Are Readability Formulas Valid Tools for Assessing Survey Question Difficulty?

Readability formulas, such as the Flesch Reading Ease formula, the Flesch-Kincaid Grade Level Index, the Gunning Fog Index, and the Dale-Chall formula are often considered to be objective measures of language complexity. Not surprisingly, survey researchers have frequently used readability scores as indicators of question difficulty and it has been repeatedly suggested that the formulas be applied during the questionnaire design phase, to identify problematic items and to assist survey designers in revising flawed questions. At the same time, the formulas have faced severe criticism among reading researchers, particularly because they are predominantly based on only two variables (word length/frequency and sentence length) that may not be appropriate predictors of language difficulty. The present study examines whether the four readability formulas named above correctly identify problematic survey questions. Readability scores were calculated for 71 question pairs, each of which included a problematic (e.g., syntactically complex, vague, etc.) and an improved version of the question. The question pairs came from two sources: (1) existing literature on questionnaire design and (2) the Q-BANK database. The analyses revealed that the readability formulas often favored the problematic over the improved version. On average, the success rate of the formulas in identifying the difficult questions was below 50 percent and agreement between the various formulas varied considerably. Reasons for this poor performance, as well as implications for the use of readability formulas during questionnaire design and testing, are discussed

Meaningful Witnessing in the United States, India & New Zealand: The Possibility Space for Digital Video Within Human Rights, Protest Movements and Activist Practices

This dissertation examines the emergence of digital video practices rooted in human rights, social justice issues and protest movements through a number of select case studies in the United States, India and New Zealand. This project analyzes and critiques the formation of digital video practices through the lens of Manuel DeLanda’s interpretation of assemblage theory. Examining interactions between crucial elements present in a possibility space that aid in the cultivation and assembling of budding forms of digital video, this study considers the implications in the relationships between both material and expressive qualities of these assemblings. The central argument of this thesis asserts that digital video practices centered on human rights, social justice and protest movements require adaptable linkages between supportive structures, creative capacities and digital video technologies in order to produce sustainable and creative digital video practices buttressed by documentary agendas that fuel their dynamic evolution. My research seeks to engage with the complexities of agency and technology and examines their significance in different contexts by providing a constructive outlet for practitioners to share the process behind their methods in order to offer insight into their creative workflow. Digital video technologies are proliferating at a rapid pace, yet very few video practices have formed that suggest linkages to documentary traditions. One can bear witness, yet to traverse video documentation in order to create a rhetorical argument of meaningful witnessing is a complex process that requires more than easy access to mobile video tools connected to the Internet. The case studies analyzed in these three democratic nations support the argument threaded throughout the project; digital video practices have the potential to thrive, albeit in pockets where formal or informal support systems are present and through assemblages where digital video technologies are constantly being adapted and an investment in human capital is paramount to the privileging of digital video tools or online platforms. Case studies that focus on individual practices in New York City and New Zealand reinforce the difficulties practitioners face when attempting to cultivate video practices without supportive structures. Comparatively with other case studies in India and New York, individual practices with long-term organizational support navigate challenges and re-assemble their practices in order to remain sustainable and influential. This study also engages with assemblage theory in the context of documentary history and contemporary digital video practices and reassesses the historic relationship between emerging photographic, film and video tools and the lens based practitioners that harness these apparatuses for documentary purposes. Like assemblings themselves, these creative associations are never smooth at their inception, but require adaptable solutions and adjustable reassemblings in order to maintain the potential for sustainable practices to develop and flourish. This dissertation argues that as digital video practices continue to evolve, they have the potential to redefine creative approaches to documentary media and the opportunity to confront historic traditions of the documentary form

Õlavarreluu proksimaalse osa murdude operatiivne ravi

Analüüsitud on õlavarreluu proksimaalse osa murdude ravi tulemusi, kus osteosünteesiks on kasutatud uut Targon-tüüpi lukustuvat naela. Jälgimisel oli 21 opereeritud haiget vanuses 52–87 aastat. Murde liigitasime AO/ASIF klassifi katsiooni järgi. Ravitulemust hindasime röntgenoloogiliselt (2, 4 ja 12 kuud pärast operatsiooni) ning spetsiaalse küsimustiku – constant shoulder score – abil. Meie kogemuse põhjal on proksimaalse õlavarreluu naela kasutamine näidustatud õla varreluu A2–C1 tüüpi murdude raviks. Operatsioonil kasutatud miniinvasiivne juurdepääs võimaldab täielikult säästa õlavarreluu pea verevarustust ja innervatsiooni, mis soodustab kiiret paranemist ja funktsiooni taastumist. Eriti on vajalik märkida, et osteopeenia ja osteoporoos ei ole vastunäidustuseks naela kasutamisel, kuna see meetod võimaldab nurkstabiilse murru fikseerimist ning jäse ei vaja lisaimmobilisatsiooni, mistõttu võib kohe alustada taastusravi. Eesti Arst 2009; 88(Lisa3):16−2

ARE TISSUES OF CHANNEL CATFISH MORE ESTROGENIC IN AREAS WITH HIGH DENSITIES OF COMBINED SEWAGE OVERFLOWS?

The Three Rivers area of Pittsburgh, Pennsylvania has more combined sewer overflow (CSO) release points than any other city in the United States. CSOs and sanitary sewer overflows (SSOs) release untreated waste directly into receiving water during wet weather events such as rain or snow. A wide range of estrogenic agents is contained in municipal wastewater, including pharmaceutical estrogens, plastic additives, pesticides and detergent breakdown products such as nonyl-phenol.The goal of this analysis was to examine estrogenicity of channel catfish fillet tissue in areas significantly impaired by CSO/SSOs compared to store-bought catfish and catfish from up-river areas on the Allegheny River that are less impacted. Estrogenicity was based on the ability of catfish fillet tissue to proliferate MCF7 human breast cancer cells. Cell proliferation was quantified using a serial dilution assay. Replicate values for each fish at each dilution were analyzed using a random intercept model. Area effects were quantified in terms of absolute and relative differences, controlling for background. In this study, cell proliferation is higher for catfish sampled from the most contaminated CSO/SSO sites than for catfish sampled from areas on the Allegheny with fewer CSOs/SSOs.The risk information concerning cumulative estrogenicity in channel catfish, in this study may provide a linkage between the ecological compounds contained in wastewaters and human health. Estradiol equivalents could be constructed from the estrogenicity index developed in this paper. These findings are significant to public health because they could help to estimate the risk of estrogenic exposure posed to those who consume channel catfish from the Three Rivers Area of Pittsburgh. The findings could also help describe the impact of estrogenic exposure in wildlife