2,343 research outputs found
Harvey, David. 2010. The Enigma of Capital and the Crises of Capitalism
Harvey, David. 2010. The Enigma of Capital and the Crises of Capitalism. New York: Oxford University Press. ISBN 978-0-19975-871-5. Cloth: 27.95 CAD. Pages: 296
Effects of high -dose chemotherapy on the bone marrow microenvironment
The bone marrow microenvironment composed in part of stromal cells provides the niche in which normal hematopoiesis occurs. Hematopoiesis generates cellular components of the immune system and blood through proliferation and differentiation of multipotent hematopoietic stem cells (HSC). In preparation for bone marrow transplantation, radiation or chemotherapy treatment temporarily disrupts the balance of hematopoiesis as many HSC and progenitor cells are destroyed. Following treatment cessation, transplanted HSC and progenitor cells migrate, or home , back to the bone marrow microenvironment and initiate productive hematopoiesis. While the mechanism of bone marrow homing is not completely understood, several soluble factors and adhesion molecules are known to have specific roles in the process. The chemokine stromal derived factor-1 (SDF-1) and the adhesion molecule vascular cell adhesion molecule-1 (VCAM-1) are critical in mediating HSC chemotaxis and adhesion, respectively. In addition, both molecules have been demonstrated to be critical for maintenance of productive hematopoiesis.;We previously demonstrated and characterized stromal cell VCAM-1 protein down-regulation following in vitro exposure to the topoisomerase II inhibitor etoposide (VP-16). VP-16-induced VCAM-1 down-regulation is associated with an impairment of stromal cell layers to support early lymphoid and myeloid cell proliferation. More recently, we evaluated stromal cell SDF-1 protein production following exposure to several chemotherapeutic drugs, and we found that bone marrow stromal cell SDF-1 protein secretion is also disrupted following VP-16 or doxorubicin exposure. SDF-1 protein reductions correlated with a reduced capacity of B-cell progenitor lines to migrate toward chemotherapy-treated stromal cell layers. Finally, we have generated and characterized murine stromal cell lines that constitutively express human VCAM-1 protein. Human VCAM-1 expression is maintained following exposure to VP-16 and overall elevation of VCAM-1 protein offset diminished viabilities in B cell progenitors following removal of exogenous IL-7.;This research will contribute to better understanding mechanistic models that address the hypothesis that aggressive chemotherapy disrupts immune system reconstitution through bone marrow microenvironment damage and disruption of molecules that regulate homing. Ultimately, this work may improve our understanding of delayed immune system recovery following aggressive chemotherapy and lead to enhanced cancer treatment strategies
Energy Transformation: Examining How Nuclear and Solar Power Could Enhance Stability in the Middle East Region and Implications for U.S. Policy
The U.S. Department of Energy projects that rapid growth in population and access to domestic resources will cause the Middle East\u27s energy consumption to increase by 95% from 2012 to 2040. Currently, Jordan, Saudi Arabia, and the United Arab Emirates do not have enough installed power capacity to handle this increase in consumption. Due to this, these states are looking to solar and nuclear power to diversify their energy sectors. This thesis\u27 focus is to examine the impending energy demand crisis that will affect Saudi Arabia, the United Arab Emirates (UAE), and Jordan. I argue that solar and nuclear power must play a vital role in these states\u27 energy sectors to stave off future power shortages, decrease reliance on domestic hydrocarbons and imported energy, and reduce CO2 emissions to lessen the effects of climate change. As nuclear energy capabilities for civilian use expand, so does the threat of nuclear terrorism or the possibility for countries to edge closer towards nuclear proliferation. The United States has a vested interest in stemming the proliferation of nuclear weapons and will need to be prepared to address this in the region in the future. Additionally, foreign powers are investing considerable resources and technology in the energy sectors in these states, which could erode U.S. influence in the region going forward
Quasi-One-Dimensional Flow for Use in Real-Time Facility Simulations
Simulations have been, and continue to play, an important role at the Arnold Engineering Development Center as an aid in control system development and operator training. These models were just simple lumped-parameter methods. Since their initial inception, over ten years ago, little work has been done to increase the fidelity of the models. The processing power of the computer hardware used by the simulations has increased dramatically during this time and this left an opening for improvements to the models adopted in the simulation. To fill this void a quasi-one-dimensional control volume has been developed to run in real-time. The new control volume accounts for changes in area, transient effects, friction and other minor pressure losses, and localized heat transfer. All of which were previously unaccounted for. This new capability was compared against known analytical solutions and applied to an example flow system that demonstrates the new features. The result is a control volume that can be used in wind tunnel, or in other industrial process, simulations to provide a more realistic model
Academic Clustering of Student-Athletes: A Case Study of Football and Basketball Programs
This study explores the topic of academic clustering within the football and men\u27s and women\u27s basketball teams at the University of Arkansas. Given the prominence of collegiate sport in America, this paper examines a relatively understudied topic regarding student-athletes and education. Using a mixed methods approach, the topic of academic clustering is analyzed statistically, as well as through in-depth interviews with student-athletes and academic advisors in the athletic department. Statistical analysis shows significant over- and under-representation of student-athletes in certain University colleges (e.g., Fulbright College of Arts and Sciences, Walton College of Business, and College of Engineering), the presence of academic clustering within the women\u27s basketball team, and a significant relationship between race and choice of major by college. Qualitative findings attempt to explain these statistical findings, as well as highlight a possible unwanted consequence of these findings
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Implications of nonlinear suspension behaviour for feedforward control of road noise in cars
Active control offers a lightweight solution to the problem of low frequency structure-borne road noise in cars. Feedforward control of road noise is predominantly limited by the difficulty of finding reference signals that are highly coherent with the sound in the cabin. One factor that could restrict the coherence of the reference signals, and therefore the performance of a linear control system, is the behaviour of nonlinear components in the suspension. The purpose of this research is to identify potential sources of nonlinearity in a car’s suspension and investigate their influence on the propagation of structure-borne road noise into the cabin. The details of experiments and simulations are described that aim to quantify the role of nonlinearity in the suspension’s dynamics, and determine to what extent it limits the performance of a linear feedforward road noise control system. The results of experiments conducted on a Nissan Leaf test vehicle are presented that establish the theoretical maximum noise reduction that can be achieved with a linear control system using reference sensors placed at the wheel hubs. Laboratory experiments on the components in the Nissan Leaf’s suspension are presented that identify the hydraulic dampers as the main source of nonlinearity in the road noise transmission path. Models of the key components in a car suspension are developed based on the results of the experiments. Models for the front and rear dampers in the Nissan Leaf are validated up to 300 Hz, and analysed to reveal the mechanisms causing their nonlinear dynamics. Models for the bushings, springs and wishbone are developed and combined into a full suspension model. The suspension model’s predictions add to the evidence from the measurements that road noise transmission is strongly influenced by nonlinearity in the damper. Some implications of the suspension’s nonlinear dynamics for feedforward control of road noise are then explored. The linear control systems used currently are often limited to one reference sensor on each suspension; a simplified analysis of a two transmission path suspension system shows that, if one path is nonlinear, a linear control system with a single reference sensor can not cancel all of the noise generated at the wheel. This thesis presents strong evidence that nonlinear suspension dynamics limit the performance of feedforward road noise controllers. A nonlinear model of vibration transmission through a suspension is developed and guidelines are suggested for reference sensor selection.Bose Corporatio
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