Configuration development study of the X-24C hypersonic research airplane, phase 1

Four hypersonic research airplane configurations found to be the most cost effective were selected for further refinement. The selection was based on a systematic analysis and evaluation of realistic designs, involving nine different configurations, evolving from three different structural/thermal concepts, coupled with existing rocket and sustainer engines. All configurations were constrained by the mission profiles, research requirements, aerodynamic envelope and maximum launch weight established by NASA

Configuration development study of the X-24C hypersonic research airplane, phase 3

The conclusion evolved from the three phased study on the configuration development of the X-24C Hypersonic Research Airplane makes it evident that it is practical to design and build the high performance National Hypersonic Flight Research Facility airplane with today's state of the art within the cost and operational constraints established by NASA. The vehicle launched at 31.75 Mg from the B-52 can cruise for 40 seconds at Mach 6.78 on scramjets. Without scramjets it can approach Mach 8 with a 453.6 Kg payload or do 70 seconds of cruise at Mach 6 with a 2.27 Mg payload. Reduction in cost is possible with a vehicle scaled to a lesser mass and capability

Configuration development study of the X-24C hypersonic research airplane

Bottom line results were made of a three-phase study to determine the feasibility of designing, building, and operating, and maintaining an air-launched high performance aircraft capable of cruising at speeds up to Mach 8 for short durations. The results show that Lockalloy heat-sink structure affords the capability for a 'work-horse' vehicle which can serve as an excellent platform for this research. It was further concluded that the performance of a blended wing body configuration surpassed that of a lifting body design for typical X-24C missions. The cost of a two vehicle program, less engines, B-52 modification and contractor support after delivery, can be kept within $70M (in Jan. 1976 dollars)

Proposing new variables for the identification of strategic groups in franchising

The identification of strategic groups in the Spanish franchising area is the main aim of this study. The authors have added some new strategic variables (not used before) to the study and have classified franchisors between sectors and distribution strategy. The results reveal the existence of four perfectly differentiated strategic groups (types of franchisors). One of the major implications of this study is that the variables that build a strategic group vary depending on the respective sector the network operates in and its distribution strategy. This fact indicates that including sector and distribution strategy is absolutely necessary to achieve good classifications of franchisor type

Performance in franchising: the effects of different management styles

Various theoretical approaches uphold the relevance of the relationship between the form of management and performance. Different management styles influence the relationships of agencies [Jensen, M.C. (1998). Foundations of organizational strategy. Cambridge, MA: Harvard University Press], the cost of governing transactions [Williamson, O.E. (1985). The economics institutions of capitalism: Firms, markets, relational contracting. New York, NY: Free Press], and the allocation of resources between the exploitation and exploration of activities [March, J.G. (1991). Exploration and exploitation in organizational learning. Organization Science, 2(1), 71-87], and this is manifested in firm performance. In light of these assumptions, this article presents an empirical verification of the relationship between the management of franchises and their performance, examining how different styles of management on the part of franchisers over their franchisees have significant effects on the growth and profits of franchiser firms.Peris-Ortiz, M.; Willoughby, MC.; Rueda Armengot, C. (2012). Performance in franchising: the effects of different management styles. Service Industries Journal. 32(16):2507-2525. doi:10.1080/02642069.2011.594876S250725253216Altinay, L., & Okumus, F. (2010). Franchise partner selection decision making. The Service Industries Journal, 30(6), 929-946. doi:10.1080/02642060802322275Child, J. (1972). Organizational Structure, Environment and Performance: The Role of Strategic Choice. Sociology, 6(1), 1-22. doi:10.1177/003803857200600101Combs, J. G., & Ketchen, D. J. (1999). CAN CAPITAL SCARCITY HELP AGENCY THEORY EXPLAIN FRANCHISING? REVISITING THE CAPITAL SCARCITY HYPOTHESIS. Academy of Management Journal, 42(2), 196-207. doi:10.2307/257092Combs, J. (2003). Why Do Firms Use Franchising as an Entrepreneurial Strategy?: A Meta-Analysis. Journal of Management, 29(3), 443-465. doi:10.1016/s0149-2063(03)00019-9COMBS, J. G., KETCHEN, D. J., & IRELAND, R. D. (2006). Effectively managing service chain organizations. Organizational Dynamics, 35(4), 357-371. doi:10.1016/j.orgdyn.2006.08.006Combs, J. G., Michael, S. C., & Castrogiovanni, G. J. (2009). Institutional Influences on the Choice of Organizational Form: The Case of Franchising. Journal of Management, 35(5), 1268-1290. doi:10.1177/0149206309336883Crook, T. R., Shook, C. L., Madden, T. M., & Morris, M. L. (2009). A review of current construct measurement in entrepreneurship. International Entrepreneurship and Management Journal, 6(4), 387-398. doi:10.1007/s11365-009-0114-7Fama, E. F., & Jensen, M. C. (1983). Agency Problems and Residual Claims. The Journal of Law and Economics, 26(2), 327-349. doi:10.1086/467038Fama, E. F., & Jensen, M. C. (1983). Separation of Ownership and Control. The Journal of Law and Economics, 26(2), 301-325. doi:10.1086/467037Gillis, W. E., & Combs, J. G. (2009). Franchisor strategy and firm performance: Making the most of strategic resource investments. Business Horizons, 52(6), 553-561. doi:10.1016/j.bushor.2009.07.001Gouldner, A. W. (1960). The Norm of Reciprocity: A Preliminary Statement. American Sociological Review, 25(2), 161. doi:10.2307/2092623Gupta, A. K., Smith, K. G., & Shalley, C. E. (2006). The Interplay Between Exploration and Exploitation. Academy of Management Journal, 49(4), 693-706. doi:10.5465/amj.2006.22083026Hambrick, D. C. (2007). Upper Echelons Theory: An Update. Academy of Management Review, 32(2), 334-343. doi:10.5465/amr.2007.24345254Hambrick, D. C., & Mason, P. A. (1984). Upper Echelons: The Organization as a Reflection of Its Top Managers. The Academy of Management Review, 9(2), 193. doi:10.2307/258434Hindle, K., & Moroz, P. (2009). Indigenous entrepreneurship as a research field: developing a definitional framework from the emerging canon. International Entrepreneurship and Management Journal, 6(4), 357-385. doi:10.1007/s11365-009-0111-xJensen, M. C., & Meckling, W. H. (1976). Theory of the firm: Managerial behavior, agency costs and ownership structure. Journal of Financial Economics, 3(4), 305-360. doi:10.1016/0304-405x(76)90026-xJensen, M. C., & Heckling, W. H. (1995). SPECIFIC AND GENERAL KNOWLEDGE, AND ORGANIZATIONAL STRUCTURE. Journal of Applied Corporate Finance, 8(2), 4-18. doi:10.1111/j.1745-6622.1995.tb00283.xKlein, B., Crawford, R. G., & Alchian, A. A. (1978). Vertical Integration, Appropriable Rents, and the Competitive Contracting Process. The Journal of Law and Economics, 21(2), 297-326. doi:10.1086/466922Liu, W., Lepak, D. P., Takeuchi, R., & Sims, H. P. (2003). Matching leadership styles with employment modes: strategic human resource management perspective. Human Resource Management Review, 13(1), 127-152. doi:10.1016/s1053-4822(02)00102-xMarch, J. G. (1991). Exploration and Exploitation in Organizational Learning. Organization Science, 2(1), 71-87. doi:10.1287/orsc.2.1.71Mitsuhashi, H., Shane, S., & Sine, W. D. (2008). Organization governance form in franchising: efficient contracting or organizational momentum? Strategic Management Journal, 29(10), 1127-1136. doi:10.1002/smj.702Orlikowski, W. J. (1992). The Duality of Technology: Rethinking the Concept of Technology in Organizations. Organization Science, 3(3), 398-427. doi:10.1287/orsc.3.3.398Ouchi, W. G. (1980). Markets, Bureaucracies, and Clans. Administrative Science Quarterly, 25(1), 129. doi:10.2307/2392231Gómez, R. S., González, I. S., & Vázquez, L. (2009). Multi-unit versus single-unit franchising: assessing why franchisors use different ownership strategies. The Service Industries Journal, 30(3), 463-476. doi:10.1080/02642060802252027Gómez, R. S., González, I. S., & Suárez, L. V. (2011). Service quality control mechanisms in franchise networks. The Service Industries Journal, 31(5), 713-723. doi:10.1080/02642060902833338Sarkees, M., & Hulland, J. (2009). Innovation and efficiency: It is possible to have it all. Business Horizons, 52(1), 45-55. doi:10.1016/j.bushor.2008.08.002Sebora, T. C., & Theerapatvong, T. (2009). Corporate entrepreneurship: a test of external and internal influences on managers’ idea generation, risk taking, and proactiveness. International Entrepreneurship and Management Journal, 6(3), 331-350. doi:10.1007/s11365-009-0108-5Shane, S., & Foo, M.-D. (1999). New Firm Survival: Institutional Explanations for New Franchisor Mortality. Management Science, 45(2), 142-159. doi:10.1287/mnsc.45.2.142Shane, S., Shankar, V., & Aravindakshan, A. (2006). The Effects of New Franchisor Partnering Strategies on Franchise System Size. Management Science, 52(5), 773-787. doi:10.1287/mnsc.1050.0449Shane, S. A. (1996). HYBRID ORGANIZATIONAL ARRANGEMENTS AND THEIR IMPLICATIONS FOR FIRM GROWTH AND SURVIVAL: A STUDY OF NEW FRANCHISORS. Academy of Management Journal, 39(1), 216-234. doi:10.2307/256637Shane, S. (2001). Organizational Incentives and Organizational Mortality. Organization Science, 12(2), 136-160. doi:10.1287/orsc.12.2.136.10108Tihula, S., & Huovinen, J. (2009). Incidence of teams in the firms owned by serial, portfolio and first-time entrepreneurs. International Entrepreneurship and Management Journal, 6(3), 249-260. doi:10.1007/s11365-008-0101-4TSUI, A. S., PEARCE, J. L., PORTER, L. W., & TRIPOLI, A. M. (1997). ALTERNATIVE APPROACHES TO THE EMPLOYEE-ORGANIZATION RELATIONSHIP: DOES INVESTMENT IN EMPLOYEES PAY OFF? Academy of Management Journal, 40(5), 1089-1121. doi:10.2307/256928Valliere, D. (2008). Reconceptualizing entrepreneurial framework conditions. International Entrepreneurship and Management Journal, 6(1), 97-112. doi:10.1007/s11365-008-0077-0Vázquez, L. (2009). How passive ownership restrictions affect the rate of franchisee failure. The Service Industries Journal, 29(6), 847-859. doi:10.1080/02642060902749419Wakkee, I., Elfring, T., & Monaghan, S. (2008). Creating entrepreneurial employees in traditional service sectors. International Entrepreneurship and Management Journal, 6(1), 1-21. doi:10.1007/s11365-008-0078-zWeick, K. E., & Roberts, K. H. (1993). Collective Mind in Organizations: Heedful Interrelating on Flight Decks. Administrative Science Quarterly, 38(3), 357. doi:10.2307/2393372Williamson, O. E. (1993). Calculativeness, Trust, and Economic Organization. The Journal of Law and Economics, 36(1, Part 2), 453-486. doi:10.1086/467284Winter, S. G. (2000). The Satisficing Principle in Capability Learning. Strategic Management Journal, 21(10-11), 981-996. doi:10.1002/1097-0266(200010/11)21:10/113.0.co;2-4Winter, S. G. (2003). Understanding dynamic capabilities. Strategic Management Journal, 24(10), 991-995. doi:10.1002/smj.318Yin, X., & Zajac, E. J. (2004). The strategy/governance structure fit relationship: theory and evidence in franchising arrangements. Strategic Management Journal, 25(4), 365-383. doi:10.1002/smj.38

A Multi-Scale Model of Intergranular Fracture and Computer Simulation of Fracture Toughness of a Carburized Steel

ABSTRACT It is no doubt that material's atomic-electronic structure determines macroscale physical properties; however, broad varieties in microstructures and heterogeneities from different scales may significantly amplify or dilute the mechanical behavior of an alloy presented at quantum scale. Hence, breakthrough of computational alloy's design lies in the capabilities to quantitatively and completely integrate key-mechanisms from different scales at each processing step, so as to obtain a unified procedure to establish quantitative relationships between composition, process, structure, properties, and performance. For this purpose, a multi-scale hierarchical model of intergranular fracture has been developed for polycrystalline systems. As an application example, it has been applied to a carburized steel that is used for gears or other components in heavy power transmission system. Based on the computations at quantum, micro, and macro scales, the prediction of fracture toughness has been obtained in accord with experiments, which reveals that an integranular cracking is mainly triggered by the stress concentration at the junctions of grain boundaries when the adhesion between adjacent grains is low. An improved toughness can be achieved by reducing impurities grain boundary segregation while increasing grains' ductility

The Majorana experiment: an ultra-low background search for neutrinoless double-beta decay

The observation of neutrinoless double-beta decay would resolve the Majorana nature of the neutrino and could provide information on the absolute scale of the neutrino mass. The initial phase of the Majorana experiment, known as the Demonstrator, will house 40 kg of Ge in an ultra-low background shielded environment at the 4850' level of the Sanford Underground Laboratory in Lead, SD. The objective of the Demonstrator is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a narrow region of interest around the 76Ge neutrinoless double-beta decay peak.Comment: Presentation for the Rutherford Centennial Conference on Nuclear Physic

The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76

The observation of neutrinoless double-beta decay would determine whether the neutrino is a Majorana particle and provide information on the absolute scale of neutrino mass. The MAJORANA Collaboration is constructing the DEMONSTRATOR, an array of germanium detectors, to search for neutrinoless double-beta decay of 76-Ge. The DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76-Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment. Operation of the DEMONSTRATOR aims to determine whether a future tonne-scale germanium experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76-Ge neutrinoless double-beta decay Q-value of 2039 keV.Comment: Submitted to AIP Conference Proceedings, 19th Particles & Nuclei International Conference (PANIC 2011), Massachusetts Institute of Technology, Cambridge, MA, USA, July 24-29, 2011; 3 pages, 1 figur

Inhibition of Src kinase activity attenuates amyloid associated microgliosis in a murine model of Alzheimer’s disease

<p>Abstract</p> <p>Background</p> <p>Microglial activation is an important histologic characteristic of the pathology of Alzheimer’s disease (AD). One hypothesis is that amyloid beta (Aβ) peptide serves as a specific stimulus for tyrosine kinase-based microglial activation leading to pro-inflammatory changes that contribute to disease. Therefore, inhibiting Aβ stimulation of microglia may prove to be an important therapeutic strategy for AD.</p> <p>Methods</p> <p>Primary murine microglia cultures and the murine microglia cell line, BV2, were used for stimulation with fibrillar Aβ1-42. The non-receptor tyrosine kinase inhibitor, dasatinib, was used to treat the cells to determine whether Src family kinase activity was required for the Aβ stimulated signaling response and subsequent increase in TNFα secretion using Western blot analysis and enzyme-linked immunosorbent assay (ELISA), respectively. A histologic longitudinal analysis was performed using an AD transgenic mouse model, APP/PS1, to determine an age at which microglial protein tyrosine kinase levels increased in order to administer dasatinib via mini osmotic pump diffusion. Effects of dasatinib administration on microglial and astroglial activation, protein phosphotyrosine levels, active Src kinase levels, Aβ plaque deposition, and spatial working memory were assessed via immunohistochemistry, Western blot, and T maze analysis.</p> <p>Results</p> <p>Aβ fibrils stimulated primary murine microglia via a tyrosine kinase pathway involving Src kinase that was attenuated by dasatinib. Dasatinib administration to APP/PS1 mice decreased protein phosphotyrosine, active Src, reactive microglia, and TNFα levels in the hippocampus and temporal cortex. The drug had no effect on GFAP levels, Aβ plaque load, or the related tyrosine kinase, Lyn. These anti-inflammatory changes correlated with improved performance on the T maze test in dasatinib infused animals compared to control animals.</p> <p>Conclusions</p> <p>These data suggest that amyloid dependent microgliosis may be Src kinase dependent <it>in vitro</it> and <it>in vivo.</it> This study defines a role for Src kinase in the microgliosis characteristic of diseased brains and suggests that particular tyrosine kinase inhibition may be a valid anti-inflammatory approach to disease. Dasatinib is an FDA-approved drug for treating chronic myeloid leukemia cancer with a reported ability to cross the blood-brain barrier. Therefore, this suggests a novel use for this drug as well as similar acting molecules.</p