277 research outputs found
Holding the Police Accountable
No full textSamuel Walker has spent his career asking who polices the police. His books and paper titles read like a laundry list of horror stories – police abuse of teenage girls, the unsuccessful nature of police “sweeps” – but he also expresses an optimism about community influence and citizen involvement. On this episode, we dive headfirst into the controversial and complicated world of law enforcement.
Samuel Walker is Emeritus Professor of Criminal Justice at the University of Nebraska, Omaha. He received a Ph.D. in American History from Ohio State University in 1973. He has taught at UNO since 1974. He is the author of 11 books on policing, criminal justice history and policy, and civil liberties. Professor Walker’s current research involves police accountability, focusing primarily on citizen oversight of the police and police Early Warning (EW) systems. The research on citizen oversight is published in Police Accountability.
Samuel Walker’s website and blog can be found here.https://commons.und.edu/why-radio-archive/1079/thumbnail.jp
Development of a high throughput 3D perfused liver tissue bioreactor
No full textThesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2006.Includes bibliographical references (p. 125-127).This thesis describes the development of a device designed for culturing liver tissue in a 3D perfused environment. Cells form tissue inside miniature channels of a scaffold, and the tissue is perfused with culture medium to create a culture microenvironment that has previously been described by the Griffith lab. In order to support this microenvironment, the reactor needs a pumping system, reservoirs and a controller. Previously, these have all been stand-alone components. This work focuses on the development of a new, integrated culture system. This system integrates 12 reactor microenvironments, reservoirs and pumping systems onto a single plate with a configuration modeled after standard multi-well plates. Each of the 12 bioreactor units utilize pneumatic pumps driven by a single external controller. This design offers substantial advantages over previous systems as it is far more user-friendly and can be used in a higher throughput capacity. The thesis describes the design and fabrication of the reactor and controller, including several models that were used during the development process. It also offers mechanical and biological characterizations of the device.by Samuel Walker Inman.S.M
Integration of real time oxygen measurements with a 3D perfused tissue culture system
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2011.Cataloged from PDF version of thesis.Includes bibliographical references (p. 115-117).In vitro models that capture the complexity of human tissue and organ behaviors in a scalable and easy-to- use format are of increasing interest for both technological applications in drug development and in basic biology research. Tissues and organs are perfused continuously with blood, which delivers nutrients, oxygen, and macromolecular regulatory molecules. In vitro culture models that incorporate local micro-perfusion in a format that allows accesses to cells and their microenvironment are desirable to a broad research community. This thesis describes a platform that features an array of bioreactors that foster three dimensional tissue organization under continuous perfusion. Each bioreactor contains a scaffold that supports formation of hundreds of 3D microscale tissue units. Perfusion through the tissue is achieved using integrated pneumatic diaphragm micropumps. Pumps continuously circulate cell culture medium within each of the fluidically isolated bioreactors in the array. Pulsatile flow from the pumps is filtered using integrated fluidic capacitors such that the flow rate through the scaffold is constant. The format of the device mimics the familiar multiwell tissue culture plate and is easily integrated into existing laboratory facilities. One desirable feature for both parsing metabolic function and assessing response to treatments is a real time read out of oxygen tension at key points in the bioreactor. Such added dimension of real time measurement significantly enhances the value of a cue-response experiment such as a liver drug toxicology study. The thesis describes optical oxygen sensors that measure the florescence decay time of a ruthenium complex, which varies predictably in different oxygen environments. The sensors excite a layer of ruthenium glued to the end of an optical fiber using a stochastic signal from a light emitting diode (LED). The response is then measured on a photodiode. System identification techniques are used to determine the relevant time constants which are subsequently converted to oxygen measurements. Application to real time monitoring of liver tissue function is used for illustration of the utility of the measurements.by Samuel Walker Inman.Ph.D
hate speech: the history of an American controversy
No full textHow did this free speech tradition develop? Hate Speech provides the first comprehensive account of the history of the hate speech controversy in the United States. Samuel Walker examines the issue, from the conflicts over the Ku Klux Klan in the 1920s and American Nazi groups in the 1930s, tot he famous Skokie episode in 1977-78, and the campus culture wars of the 1990s. The author argues that the civil rights movement played a central role in developing this country's strong free speech tradition. The courts were very concerned about protecting the provocative and even offensive forms of expression by civil rights forces. Civil rights groups, therefore, preferred to protect rather than restrict offensive speech?even if it meant protecting racist speech
Challenges in Using Cultured Primary Rodent Hepatocytes or Cell Lines to Study Hepatic HDL Receptor SR-BI Regulation by Its Cytoplasmic Adaptor PDZK1
No full textBackground:
PDZK1 is a four PDZ-domain containing cytoplasmic protein that binds to a variety of membrane proteins via their C-termini and can influence the abundance, localization and/or function of its target proteins. One of these targets in hepatocytes in vivo is the HDL receptor SR-BI. Normal hepatic expression of SR-BI protein requires PDZK1 - <5% of normal hepatic SR-BI is seen in the livers of PDZK1 knockout mice. Progress has been made in identifying features of PDZK1 required to control hepatic SR-BI in vivo using hepatic expression of wild-type and mutant forms of PDZK1 in wild-type and PDZK1 KO transgenic mice. Such in vivo studies are time consuming and expensive, and cannot readily be used to explore many features of the underlying molecular and cellular mechanisms.
Methodology/Principal Findings:
Here we have explored the potential to use either primary rodent hepatocytes in culture using 2D collagen gels with newly developed optimized conditions or PDZK1/SR-BI co-transfected cultured cell lines (COS, HEK293) for such studies. SR-BI and PDZK1 protein and mRNA expression levels fell rapidly in primary hepatocyte cultures, indicating this system does not adequately mimic hepatocytes in vivo for analysis of the PDZK1 dependence of SR-BI. Although PDZK1 did alter SR-BI protein expression in the cell lines, its influence was independent of SR-BI’s C-terminus, and thus is not likely to occur via the same mechanism as that which occurs in hepatocytes in vivo.
Conclusions/Significance:
Caution must be exercised in using primary hepatocytes or cultured cell lines when studying the mechanism underlying the regulation of hepatic SR-BI by PDZK1. It may be possible to use SR-BI and PDZK1 expression as sensitive markers for the in vivo-like state of hepatocytes to further improve primary hepatocyte cell culture conditions.National Institutes of Health (U.S.) (Grant HL052212)National Institutes of Health (U.S.) (Grant HL066105)National Institutes of Health (U.S.) (Grant ES015241)National Institutes of Health (U.S.) (Grant GM068762
Perfused multiwell plate for 3D liver tissue engineering
No full textIn vitro models that capture the complexity of in vivo tissue and organ behaviors in a scalable and easy-to-use format are desirable for drug discovery. To address this, we have developed a bioreactor that fosters maintenance of 3D tissue cultures under constant perfusion and we have integrated multiple bioreactors into an array in a multiwell plate format. All bioreactors are fluidically isolated from each other. Each bioreactor in the array contains a scaffold that supports formation of hundreds of 3D microscale tissue units. The tissue units are perfused with cell culture medium circulated within the bioreactor by integrated pneumatic diaphragm micropumps. Electronic controls for the pumps are kept outside the incubator and connected to the perfused multiwell by pneumatic lines. The docking design and open-well bioreactor layout make handling perfused multiwell plates similar to using standard multiwell tissue culture plates. A model of oxygen consumption and transport in the circulating culture medium was used to predict appropriate operating parameters for primary liver cultures. Oxygen concentrations at key locations in the system were then measured as a function of flow rate and time after initiation of culture to determine oxygen consumption rates. After seven days of culture, tissue formed from cells seeded in the perfused multiwell reactor remained functionally viable as assessed by immunostaining for hepatocyte and liver sinusoidal endothelial cell (LSEC) phenotypic markers.National Institute of Environmental Health Sciences (grant number 5P30ES002109-30)National Institutes of Health (U.S.) (NIH grant number 5R01ES015241)DuPont MIT AlliancePfizer Inc.National Science Foundation (U.S.) (NSF grant number EEC-9843342
An Invincible Army?: Reading 1 Samuel 4-6 and 2 Samuel 6 as a Deuteronomistic Corrective to Exilic Misconceptions of the Ark
No full textThe surprising nature of the events which surround the ark in 1 Samuel 4-6 and 2 Samuel 6 raises significant questions about the conflicting concepts of this central Israelite object. This study will consider these narratives in light of their wider contexts, silhouetting the presentation of the ark in these chapters against the understanding of the ark in the Deuteronomistic History and of divine statues in the ancient Near East. It will argue that the Deuteronomistic author used the events within these narratives are a means of dispelling and correcting the views surrounding the ark and the temple which were held by both the people of Israel and their enemies during the time of the Babylonian exile. The narratives of the ark offer a microcosm of the exile, providing both an explanation for Israel’s fate and a hope for their return
Infinite limits of finite-dimensional permutation structures, and their automorphism groups: between model theory and combinatorics
No full textIn the course of classifying the homogeneous permutations, Cameron introduced the viewpoint of permutations as structures in a language of two linear orders [7], and this structural viewpoint is taken up here. The majority of this thesis is concerned with Cameron's problem of classifying the homogeneous structures in a language of finitely many linear orders, which we call finite-dimensional permutation structures. Towards this problem, we present a construction that we conjecture produces all such structures. Some evidence for this conjecture is given, including the classification of the homogeneous 3-dimensional permutation structures. We next consider the topological dynamics, in the style of Kechris, Pestov, and Todorčević, of the automorphism groups of the homogeneous finite-dimensional permutation structures we have constructed, which requires proving a structural Ramsey theorem for all the associated amalgamation classes. Because the 0-definable equivalence relations in these homogeneous finite-dimensional permutation structures may form arbitrary finite distributive lattices, the model-theoretic algebraic closure operation may become quite complex, and so we require the framework recently introduced by Hubička and Nešetril [16]. Finally, we turn to the interaction of model theory with more classical topics in the theory of permutation avoidance classes. We consider the decision problem for whether a finitely-constrained permutation avoidance class is atomic, or equivalently, has the joint embedding property. As a first approximation to this problem, we prove the undecidability of the corresponding decision problem in the category of graphs. Modifying this proof also gives the undecidability, in the category of graphs, of the corresponding decision problem for the joint homomorphism property, which is of interest in infinite-domain constraint satisfaction problems. The results in the first 8 chapters of this thesis largely appeared in the previous articles [4], [5], and [6]. In many places the arguments and context have been expanded upon, and in the case of some arguments from [4], they have been simplified.Ph.D.Includes bibliographical referencesby Samuel Walker Braunfel
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