537 research outputs found
Preliminary study of the diversion of 283 m3 s-1 (10,000 cfs) from Lake Superior to the Missouri River basin
Trans-basin diversion is an established practice in this country. The High Plains Study authorized by the U.S. Congress in 1976 examined large-scale intra-basin diversion to replenish the depleted groundwater resources of the Ogallala aquifer. A portion of this intra-basin diversion could come from the Missouri River basin. This study presents the preliminary engineering associated with a large-scale diversion of Lake Superior water out of the Great Lakes and into the Missouri River basin in order to replace intra-basin water diverted for recharge of the Ogallala aquifer. The magnitude of the diversion is 283 m3 s-1 (10,000 cfs). The first cost of the conveyance structure is estimated at US 7 billion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24926/1/0000353.pd
Order and disorder in columnar joints
Columnar joints are three-dimensional fracture networks that form in cooling basalt and several other media. The network organizes itself into ordered, mostly hexagonal columns. The same pattern can be observed on a smaller scale in desiccating starch. We show how surface boundary conditions in the desiccation of starch affect the formation of columnar joints. Under constant drying power conditions, we find a power law dependence of columnar cross-sectional area with depth, while under constant drying rate conditions this coarsening is eventually halted. Discontinuous transitions in pattern scale can be observed under constant external conditions, which may prompt a reinterpretation of similar transitions found in basalt. Starch patterns are statistically similar to those found in basalt, suggesting that mature columnar jointing patterns contain inherent residual disorder, but are statistically scale invariant
Recommended from our members
The Advent of the Transnational TV Format Trading System: A Global Commodity Chain Analysis
This article argues that the format business transformed into a trading system in the 2000s, system being defined as a singular transnational space structured by networks of interdependent economic agents, firms, institutions and places. Following the global commodity chain/global value chain approach set out by Immanuel Wallerstein and developed by Gary Gereffi, this article then examines each dimension of the global TV format commodity chain that runs through this trading system. Beginning with the governance structure, this article counter-intuitively asserts that despite the current boom in TV production, it is a buyer-driven chain with power resting firmly in the hands of those making the acquisitions: the broadcasters. Considering the chain’s geographical configuration, this article identifies three tiers of format exporters and specific trade routes along which most TV formats travel. These findings enable us to reassess the claims made by the cosmopolitanization thesis about the nature of media globalization. Contrary to this thesis, this article asserts the need to comprehend media globalization within the context of an expanding capitalist world-system, and shows that the new transnational TV format trade and its commodity chain replicate the inequalities and power structures of former trading systems
Conceptualising a Dynamic Technology Practice in Education Using Argyris and Schön's Theory of Action
Despite substantial national effort to integrate technology in education, it seems that practitioners in the education system are not working in line with the given policy. Evidence from large-scale studies of students’ technology practices at school over the last decade show disparities in student practices. The observed gap between the micro and the macro level call for a closer exploration. Research that explores the influence of social and organizational factors may be useful for understanding the processes behind such gaps. Argyris and Schön’s ‘Theory of Action’ (1978) is proposed as an example of an organizational theory that can be adopted in educational technology research to move towards understanding the complexities of technology practice. To encourage discourse and application of Argyris and Schön’s theory in the field of educational technology research, this paper introduces the theory, a review of its empirical application in research of teacher educations’ technology practice and relevant conceptual work. The paper presents a conceptual framework based on Argyris and Schön’s theory that has been developed through two recent studies, and invites its application in future research and development
Habitat Associations of Fish Species of Greatest Conservation Need at Multiple Spatial Scales in Wadeable Iowa Streams
Fish and habitat data were collected from 84 wadeable stream reaches in the Mississippi River drainage of Iowa to predict the occurrences of seven fish species of greatest conservation need and to identify the relative importance of habitat variables measured at small (e.g., depth, velocity, and substrate) and large (e.g., stream order, elevation, and gradient) scales in terms of their influence on species occurrences. Multiple logistic regression analysis was used to predict fish species occurrences, starting with all possible combinations of variables (5 large-scale variables, 13 small-scale variables, and all 18 variables) but limiting the final models to a maximum of five variables. Akaike’s information criterion was used to rank candidate models, weight model parameters, and calculate model-averaged predictions. On average, the correct classification rate (CCR = 80%) and Cohen’s kappa (κ = 0.59) were greatest for multiple-scale models (i.e., those including both large-scale and small-scale variables), intermediate for small-scale models (CCR = 75%; κ = 0.49), and lowest for large-scale models (CCR = 73%; κ = 0.44). The occurrence of each species was associated with a unique combination of large-scale and small-scale variables. Our results support the necessity of understanding factors that constrain the distribution of fishes across spatial scales to ensure that management decisions and actions occur at the appropriate scale
Robotics and automation in the city: a research agenda
Globally cities are becoming experimental sites for new forms of robotic and automation technologies applied across a wide variety of sectors in multiple areas of economic and social
life. As these innovations leave the laboratory and factory, this paper analyses how robotics and automation systems are being layered upon existing urban digital networks, extending the
capabilities and capacities of human agency and infrastructure networks, and reshaping the city and citizen’s everyday experiences. To date, most work in this field has been speculative and isolated in nature. We set out a research agenda that goes beyond analysis of discrete applications and effects, to investigate how robotics and automation connect across urban domains and the implications for: differential urban geographies, the selective enhancement of individuals and collective management of infrastructures, the socio-spatial sorting of cities and the potential for responsible urban innovation
Extensive necrosis of visceral melanoma metastases after immunotherapy
<p>Abstract</p> <p>Background</p> <p>The prognosis for metastatic melanoma remains poor even with traditional decarbazine or interferon therapy. 5-year survival is markedly higher amongst patients undergoing metastatectomy. Unfortunately not all are suitable for metastatectomy. Alternative agents for systemic therapy have, to date, offered no greater rates of survival beyond traditional therapy. A toll-like receptor 9 agonist, PF-3512676 (formerly known as CPG 7909) is currently being evaluated for its potential.</p> <p>Case presentation</p> <p>We present the case of a 54-year-old Caucasian male with completely resected metastatic cutaneous melanoma after immunotherapy. The patient initially progressed during adjuvant high-dose interferon, with metastases to the liver, spleen, and pelvic lymph nodes. During an 18-month treatment period with PF-3512676 (formerly known as CPG 7909), a synthetic cytosine-phosphorothioate-guanine rich oligodeoxynucleotide, slow radiologic disease progression was demonstrated at the original disease sites. Subsequent excision of splenic and pelvic nodal metastases was performed, followed by resection of the liver metastases. Histologic examination of both hepatic and splenic melanoma metastases showed extensive necrosis. Subsequent disease-free status was demonstrated by serial positron emission tomography (PET).</p> <p>Conclusion</p> <p>Existing evidence from phase I/II trials suggests systemic treatment with PF-3512676 is capable of provoking a strong tumor-specific immune response and may account for the prolonged tumor control in this instance.</p
Inhibitory Effects of Prior Low-dose X-irradiation on Ischemia-reperfusion Injury in Mouse Paw
We have reported that low-dose, unlike high-dose, irradiation enhanced antioxidation function and reduced oxidative damage. On the other hand, ischemia-reperfusion injury is induced by reactive oxygen species. In this study, we examined the inhibitory effects of prior low-dose X-irradiation on ischemia-reperfusion injury in mouse paw. BALB/c mice were irradiated by sham or 0.5 Gy of X-ray. At 4 hrs after irradiation, the left hind leg was bound 10 times with a rubber ring for 0.5, 1, or 2 hrs and the paw thickness was measured. Results show that the paw swelling thickness by ischemia for 0.5 hr was lower than that for 2 hrs. At 1 hr after reperfusion from ischemia for 1 hr, superoxide dismutase activity in serum was increased in those mice which received 0.5 Gy irradiation and in the case of the ischemia for 0.5 or 1 hr, the paw swelling thicknesses were inhibited by 0.5 Gy irradiation. In addition, interstitial edema in those mice which received 0.5 Gy irradiation was less than that in the mice which underwent by sham irradiation. These findings suggest that the ischemia-reperfusion injury is inhibited by the enhancement of antioxidation function by 0.5 Gy irradiation
- …