Rerandomization to improve covariate balance in experiments

Randomized experiments are the "gold standard" for estimating causal effects, yet often in practice, chance imbalances exist in covariate distributions between treatment groups. If covariate data are available before units are exposed to treatments, these chance imbalances can be mitigated by first checking covariate balance before the physical experiment takes place. Provided a precise definition of imbalance has been specified in advance, unbalanced randomizations can be discarded, followed by a rerandomization, and this process can continue until a randomization yielding balance according to the definition is achieved. By improving covariate balance, rerandomization provides more precise and trustworthy estimates of treatment effects.Comment: Published in at http://dx.doi.org/10.1214/12-AOS1008 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Hard dihadron correlations in heavy-ion collisions at RHIC and LHC

High transverse momentum (P_T) processes are considered to be an important tool to probe and understand the medium produced in ultrarelativistic heavy-ion collisions via the interaction of hard, perturbatively produced partons with the medium. In this context, triggered hard dihadron correlations constitute a class of observables set between hard single inclusive hadrons (dominated by the leading jet fragments) and fully reconstructed jets - while they probe some features of the perturbative QCD evolution of a parton shower in the medium, they do not suffer from the problem of finding a suitable separation between soft perturbative (jet-like) and soft non-perturbative (medium-like) physics as the identification of full jets does. On the other hand, the trigger requirement introduces non-trivial complications to the process, which makes the medium-modification of the correlation pattern difficult and non-intuitive to understand. In this work, we review the basic physics underlying triggered dihadron correlations and make a systematic comparison of several combinations of medium evolution and parton-medium interaction models with the available data from 200 AGeV Au-Au collisions at RHIC. We also discuss the expected results for 2.76 ATeV Pb-Pb collisions at the LHC.Comment: 13 pages, 7 figures, submitted to PR

Aperiodic tilings and entropy

In this paper we present a construction of Kari-Culik aperiodic tile set - the smallest known until now. With the help of this construction, we prove that this tileset has positive entropy. We also explain why this result was not expected

Anesthetic Considerations for Phantom Limb Pain

Title: Anesthetic Considerations for Phantom Limb Pain Background: Phantom limb pain (PLP) is a phenomenon where pain develops or is perceived in a body part that has been removed. With the prevalence of peripheral vascular disease secondary to diabetes, amputation rates are expected to increase in the next decade. Chronic pain syndromes such as phantom limb pain are difficult to manage and treat Purpose: The purpose of this project is to detennine if preemptive analgesia for limb amputation is effective in the prevention of PLP Process: A comprehensive review of the literature was perfonned using multiple databases from the Harley E. French Library of Health Sciences at the University of North Dakota. Databases searched included PubMed, CINAHL, and Scopus. Research findings were extensively reviewed to detennine relevance to the research question Results: Although extensive research has been perfonned, the exact mechanism for the development of chronic neuropathic PLP remains a mystery. The large variation in the prevalence, symptoms and development suggests a multifactorial origin for PLP. Many theories have evolved ranging from pathologic changes of somatosensory systems to cortical reorganization of higher brain structures. Inconsistent results from multiple clinical studies of different preemptive analgesic techniques have added to the mystery of PLP. Specific treatment guidelines have not been universally accepted. However, researchers agree that preemptive analgesia is beneficial for alleviating pain in the preoperative and immediate postoperative period Implication: Pain is a constant battle in the field of anesthesia. Anesthesia professionals should be versed in the pathophysiology of pain and methods to alleviate pain syndromes in patient

Energy loss in a fluctuating hydrodynamical background

Recently it has become apparent that event-by-event fluctuations in the initial state of hydrodynamical modelling of ultrarelativistic heavy-ion collisions are crucial in order to understand the full centrality dependence of the elliptic flow coefficient v_2. In particular, in central collisions the density fluctuations play a major role in generating the spatial eccentricity in the initial state. This raises the question to what degree high P_T physics, in particular leading-parton energy loss, which takes place in the background of an evolving medium, is sensitive to the presence of the event-by-event density fluctuations in the background. In this work, we report results for the effects of fluctuations on the nuclear modification factor R_AA in both central and noncentral sqrt(s_NN) = 200 GeV Au+Au collisions at RHIC. Two different types of energy-loss models, a radiative and an elastic, are considered. In particular, we study the dependence of the results on the assumed spatial size of the density fluctuations, and discuss the angular modulation of R_AA with respect to the event plane.Comment: 9 pages, 9 figure

Chikashshanompaat bílli'ya: The Chickasaw language is forever

Drawing on research with Chickasaw citizens committed to Chikashshanompa’ (Chickasaw language) reclamation work, this chapter focuses on how Chikashshanompa’ learners and teachers engage in nation-building as they work to ensure the continuance of Chikashshanompa’ for future generations. Complementing Michelle Cooke’s chapter about teaching university Chickasaw language courses, I draw upon findings of 5 years of research during 2010–2015 with Chickasaws committed to learning, teaching, and actively using Chikashshanompa’. Together, we dedicate our chapters to the life’s work of Jerry Imotichey (1938–2016)—Michelle’s co-instructor and a language teacher to both of us. Jerry passed on in 2016, having inspired many with his love for his first language and passion for teaching others.Ye

#KeepOurLanguagesStrong: Indigenous language revitalization on social media during the early COVID-19 pandemic

Indigenous communities, organizations, and individuals work tirelessly to #KeepOurLanguagesStrong. The COVID-19 pandemic was potentially detrimental to Indigenous language revitalization (ILR) as this mostly in-person work shifted online. This article shares findings from an analysis of public social media posts, dated March through July 2020 and primarily from Canada and the US, about ILR and the COVID-19 pandemic. The research team, affiliated with the NEȾOLṈEW̱ “one mind, one people” Indigenous language research partnership at the University of Victoria, identified six key themes of social media posts concerning ILR and the pandemic, including: 1. language promotion, 2. using Indigenous languages to talk about COVID-19, 3. trainings to support ILR, 4. language education, 5. creating and sharing language resources, and 6. information about ILR and COVID-19. Enacting the principle of reciprocity in Indigenous research, part of the research process was to create a short video to share research findings back to social media. This article presents a selection of slides from the video accompanied by an in-depth analysis of the themes. Written about the pandemic, during the pandemic, this article seeks to offer some insights and understandings of a time during which much is uncertain. Therefore, this article does not have a formal conclusion; rather, it closes with ideas about long-term implications and future research directions that can benefit ILR.Ye

College Readiness Initiative: AVID and Navigation 101

The purpose of this report is to provide summative feedback to personnel at the Office of Superintendent of Public Instruction (OSPI) and at the College Spark Washington regarding evidence of implementation and impact of the Advancement via Individual Determination (AVID) and Navigation 101 programs in schools funded by the College Readiness Initiative (CRI) in Washington State. The report, while addressing the effects of both programs, is also designed to provide formative feedback to assist in ongoing program development

Lack of Regional Surface Differences in Mouse Bladder Urothelium: A Scanning Electron Microscopic Study

The surface structures of mouse urinary bladder epithelium, the urothelium, were examined in SEM. The entire surface area of both a moderately and a well stretched bladder were studied. No regional differences were found in either case. The moderately stretched bladder showed deep folds, while the well stretched bladder had only small folds giving the bladder an accordion-like appearance. In both bladders the typical surface structures were microridges arranged in a honeycomb-like pattern. The present study indicates that focal or regional differences found in bladders treated with chemicals or exposed to radiation are a result of the treatment itself, and not of differences normally occurring in the urothelium