1,000 research outputs found

    Adaptive finite element method assisted by stochastic simulation of chemical systems

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    Stochastic models of chemical systems are often analysed by solving the corresponding\ud Fokker-Planck equation which is a drift-diffusion partial differential equation for the probability\ud distribution function. Efficient numerical solution of the Fokker-Planck equation requires adaptive mesh refinements. In this paper, we present a mesh refinement approach which makes use of a stochastic simulation of the underlying chemical system. By observing the stochastic trajectory for a relatively short amount of time, the areas of the state space with non-negligible probability density are identified. By refining the finite element mesh in these areas, and coarsening elsewhere, a suitable mesh is constructed and used for the computation of the probability density

    Bipolar spintronics: From spin injection to spin-controlled logic

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    An impressive success of spintronic applications has been typically realized in metal-based structures which utilize magnetoresistive effects for substantial improvements in the performance of computer hard drives and magnetic random access memories. Correspondingly, the theoretical understanding of spin-polarized transport is usually limited to a metallic regime in a linear response, which, while providing a good description for data storage and magnetic memory devices, is not sufficient for signal processing and digital logic. In contrast, much less is known about possible applications of semiconductor-based spintronics and spin-polarized transport in related structures which could utilize strong intrinsic nonlinearities in current-voltage characteristics to implement spin-based logic. Here we discuss the challenges for realizing a particular class of structures in semiconductor spintronics: our proposal for bipolar spintronic devices in which carriers of both polarities (electrons and holes) contribute to spin-charge coupling. We formulate the theoretical framework for bipolar spin-polarized transport, and describe several novel effects in two- and three-terminal structures which arise from the interplay between nonequilibrium spin and equilibrium magnetization.Comment: 16 pages, 7 figure

    Jaw and Long Bone Marrows Have a Different Osteoclastogenic Potential

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    Osteoclasts, the multinucleated bone-resorbing cells, arise through fusion of precursors from the myeloid lineage. However, not all osteoclasts are alike; osteoclasts at different bone sites appear to differ in numerous respects. We investigated whether bone marrow cells obtained from jaw and long bone differed in their osteoclastogenic potential. Bone marrow cells from murine mandible and tibiae were isolated and cultured for 4 and 6 days on plastic or 6 and 10 days on dentin. Osteoclastogenesis was assessed by counting the number of TRAP+ multinucleated cells. Bone marrow cell composition was analyzed by FACS. The expression of osteoclast- and osteoclastogenesis-related genes was studied by qPCR. TRAP activity and resorptive activity of osteoclasts were measured by absorbance and morphometric analyses, respectively. At day 4 more osteoclasts were formed in long bone cultures than in jaw cultures. At day 6 the difference in number was no longer observed. The jaw cultures, however, contained more large osteoclasts on plastic and on dentin. Long bone marrow contained more osteoclast precursors, in particular the myeloid blasts, and qPCR revealed that the RANKL:OPG ratio was higher in long bone cultures. TRAP expression was higher for the long bone cultures on dentin. Although jaw osteoclasts were larger than long bone osteoclasts, no differences were found between their resorptive activities. In conclusion, bone marrow cells from different skeletal locations (jaw and long bone) have different dynamics of osteoclastogenesis. We propose that this is primarily due to differences in the cellular composition of the bone site-specific marrow

    Ownership competence

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    Ownership is fundamental to firm strategy, organization, and governance. Standard ownership concepts—mainly derived from agency and incomplete contracting theories—focus on its incentive effects. However, these concepts and theories neglect ownership's role as an instrument to match judgment about resource use and governance with the firm's evolving environment under uncertainty. We develop the concept of ownership competence—the skill with which ownership is used as an instrument to create value—and decompose it into matching competence (what to own), governance competence (how to own), and timing competence (when to own). We describe how property rights of use, appropriation, and transfer relate to the three ownership competences and show how our theory offers a fresh perspective into the role of ownership for value generation

    Fine-Scale Genetic Structure Arises during Range Expansion of an Invasive Gecko

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    Processes of range expansion are increasingly important in light of current concerns about invasive species and range shifts due to climate change. Theoretical studies suggest that genetic structuring may occur during range expansion. Ephemeral genetic structure can have important evolutionary implications, such as propagating genetic changes along the wave front of expansion, yet few studies have shown evidence of such structure. We tested the hypothesis that genetic structure arises during range expansion in Hemidactylus mabouia, a nocturnal African gecko recently introduced to Florida, USA. Twelve highly variable microsatellite loci were used to screen 418 individuals collected from 43 locations from four sampling sites across Florida, representing a gradient from earlier (∼1990s) to very recent colonization. We found earlier colonized locations had little detectable genetic structure and higher allelic richness than more recently colonized locations. Genetic structuring was pronounced among locations at spatial scales of tens to hundreds of meters near the leading edge of range expansion. Despite the rapid pace of range expansion in this introduced gecko, dispersal is limited among many suitable habitat patches. Fine-scale genetic structure is likely the result of founder effects during colonization of suitable habitat patches. It may be obscured over time and by scale-dependent modes of dispersal. Further studies are needed to determine if such genetic structure affects adaptation and trait evolution in range expansions and range shifts

    Genome sequence of an Australian kangaroo, Macropus eugenii, provides insight into the evolution of mammalian reproduction and development.

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    BACKGROUND: We present the genome sequence of the tammar wallaby, Macropus eugenii, which is a member of the kangaroo family and the first representative of the iconic hopping mammals that symbolize Australia to be sequenced. The tammar has many unusual biological characteristics, including the longest period of embryonic diapause of any mammal, extremely synchronized seasonal breeding and prolonged and sophisticated lactation within a well-defined pouch. Like other marsupials, it gives birth to highly altricial young, and has a small number of very large chromosomes, making it a valuable model for genomics, reproduction and development. RESULTS: The genome has been sequenced to 2 × coverage using Sanger sequencing, enhanced with additional next generation sequencing and the integration of extensive physical and linkage maps to build the genome assembly. We also sequenced the tammar transcriptome across many tissues and developmental time points. Our analyses of these data shed light on mammalian reproduction, development and genome evolution: there is innovation in reproductive and lactational genes, rapid evolution of germ cell genes, and incomplete, locus-specific X inactivation. We also observe novel retrotransposons and a highly rearranged major histocompatibility complex, with many class I genes located outside the complex. Novel microRNAs in the tammar HOX clusters uncover new potential mammalian HOX regulatory elements. CONCLUSIONS: Analyses of these resources enhance our understanding of marsupial gene evolution, identify marsupial-specific conserved non-coding elements and critical genes across a range of biological systems, including reproduction, development and immunity, and provide new insight into marsupial and mammalian biology and genome evolution

    Influence of firm size on the competencies required to management engineers in the Jordanian telecommunications sector

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    This is an Accepted Manuscript of an article published by Taylor & Francis in European Journal of Engineering Education on [13 jun 2016], available online:http://www.tandfonline.com/ doi/abs/10.1080/03043797.2016.1197890.[EN] The objective of this study is to identify the competencies required to achieve success in the transition from higher education to the labour market based on the perceptions of employers. This paper analyses the assessments made by a group of engineering company employers. An item-battery of 20 competencies was grouped into 3 dimensions by using factor analysis. Subsequently, respondents scores were also clustered into three groups and characterised through contingency tables. The competencies demanded by employers were grouped into business and finance, problem-solving and strategic planning. Significant differences were found between responses from employers working in medium and small companies, who placed more importance on competencies related to problem-solving and strategic planning, and employers in big companies, who were more concerned about the difficulties of finding well-trained graduates. The findings from this paper have important implications for research in the areas of higher education and organisations that usually employ graduate engineers.The authors would like to thank the Education, Audiovisual and Culture Executive Agency (EACEA) [Tempus program. Project number 511074] of the European Commission for providing funding for conducting this study. This publication reflects the views only of the authors, and the Commission cannot be held responsible for any use which may be made of the information contained therein.Conchado Peiró, A.; Bas Cerdá, MDC.; Gharaibeh, KM.; Kaylani, H. (2016). Influence of firm size on the competencies required to management engineers in the Jordanian telecommunications sector. European Journal of Engineering Education. 1-14. doi:10.1080/03043797.2016.1197890S114ALLEN, J., & DE WEERT, E. (2007). What Do Educational Mismatches Tell Us About Skill Mismatches? A Cross-country Analysis. European Journal of Education, 42(1), 59-73. doi:10.1111/j.1465-3435.2007.00283.xBarrella, E. M., & Buffinton, K. W. (2009). Corporate Assessment of Strategic Issues in Technology Management. Engineering Management Journal, 21(1), 27-33. doi:10.1080/10429247.2009.11431795Bartram, D., Lindley, P. A., Marshall, L., & Foster, J. (1995). The recruitment and selection of young people by small businesses. Journal of Occupational and Organizational Psychology, 68(4), 339-358. doi:10.1111/j.2044-8325.1995.tb00592.xBehrends, T. (2007). Recruitment Practices in Small and Medium Size Enterprises. An Empirical Study among Knowledge-intensive Professional Service Firms. management revu, 18(1), 55-74. doi:10.5771/0935-9915-2007-1-55Boshuizen, H. P. A. (s. f.). Does Practice Make Perfect? Innovation and Change in Professional Education, 73-95. doi:10.1007/1-4020-2094-5_5Branine, M. (2008). Graduate recruitment and selection in the UK. Career Development International, 13(6), 497-513. doi:10.1108/13620430810901660Butler, C. J., & Chinowsky, P. S. (2006). Emotional Intelligence and Leadership Behavior in Construction Executives. Journal of Management in Engineering, 22(3), 119-125. doi:10.1061/(asce)0742-597x(2006)22:3(119)Carbone, T. A., & Gholston, S. (2004). Project Manager Skill Development: A Survey of Programs and Practitioners. Engineering Management Journal, 16(3), 10-16. doi:10.1080/10429247.2004.11415252Cassell, C., Nadin, S., Gray, M., & Clegg, C. (2002). Exploring human resource management practices in small and medium sized enterprises. Personnel Review, 31(6), 671-692. doi:10.1108/00483480210445962Cattell, R. B., & Vogelmann, S. (1977). A Comprehensive Trial Of The Scree And Kg Criteria For Determining The Number Of Factors. Multivariate Behavioral Research, 12(3), 289-325. doi:10.1207/s15327906mbr1203_2Chan, A. P. C., Ho, D. C. K., & Tam, C. M. (2001). Effect of Interorganizational Teamwork on Project Outcome. Journal of Management in Engineering, 17(1), 34-40. doi:10.1061/(asce)0742-597x(2001)17:1(34)Coll, R. K., & Zegwaard, K. E. (2006). Perceptions of desirable graduate competencies for science and technology new graduates. Research in Science & Technological Education, 24(1), 29-58. doi:10.1080/02635140500485340Cronbach, L. J. (1951). Coefficient alpha and the internal structure of tests. Psychometrika, 16(3), 297-334. doi:10.1007/bf02310555Dekker, R., de Grip, A., & Heijke, H. (2002). The effects of training and overeducation on career mobility in a segmented labour market. International Journal of Manpower, 23(2), 106-125. doi:10.1108/01437720210428379Elfenbein, D. W., Hamilton, B. H., & Zenger, T. R. (2010). The Small Firm Effect and the Entrepreneurial Spawning of Scientists and Engineers. Management Science, 56(4), 659-681. doi:10.1287/mnsc.1090.1130Farr, J. V., & Brazil, D. M. (2009). Leadership Skills Development for Engineers. Engineering Management Journal, 21(1), 3-8. doi:10.1080/10429247.2009.11431792Garen, J. E. (1985). Worker Heterogeneity, Job Screening, and Firm Size. Journal of Political Economy, 93(4), 715-739. doi:10.1086/261327Gharaibeh, K. M., Kaylani, H., Murphy, N., Brennan, C., Itradat, A., Al-Bataineh, M., … Bany Salameh, H. (2014). A Masters Programme in telecommunications management – demand-based curriculum design. European Journal of Engineering Education, 40(3), 267-284. doi:10.1080/03043797.2014.944104Hayes, J., Rose‐Quirie, A., & Allinson, C. W. (2000). Senior managers’ perceptions of the competencies they require for effective performance: implications for training and development. Personnel Review, 29(1), 92-105. doi:10.1108/00483480010295835Hersch, J. (1991). Education Match and Job Match. The Review of Economics and Statistics, 73(1), 140. doi:10.2307/2109696Hoegl, M., & Parboteeah, K. P. (2007). Creativity in innovative projects: How teamwork matters. Journal of Engineering and Technology Management, 24(1-2), 148-166. doi:10.1016/j.jengtecman.2007.01.008Hoegl, M., Praveen Parboteeah, K., & Gemuenden, H. G. (2003). When teamwork really matters: task innovativeness as a moderator of the teamwork–performance relationship in software development projects. Journal of Engineering and Technology Management, 20(4), 281-302. doi:10.1016/j.jengtecman.2003.08.001Van Hoorn, T. P. (1979). Strategic planning in small and medium-sized companies. Long Range Planning, 12(2), 84-91. doi:10.1016/0024-6301(79)90076-1HUSELID, M. A. (1995). THE IMPACT OF HUMAN RESOURCE MANAGEMENT PRACTICES ON TURNOVER, PRODUCTIVITY, AND CORPORATE FINANCIAL PERFORMANCE. Academy of Management Journal, 38(3), 635-672. doi:10.2307/256741Kaiser, H. F. (1958). The varimax criterion for analytic rotation in factor analysis. Psychometrika, 23(3), 187-200. doi:10.1007/bf02289233Kaufman, L., & Rousseeuw, P. J. (Eds.). (1990). Finding Groups in Data. Wiley Series in Probability and Statistics. doi:10.1002/9780470316801Krug, J. (1997). People Skills: Teamwork. Journal of Management in Engineering, 13(2), 15-16. doi:10.1061/(asce)0742-597x(1997)13:2(15)Male, S. A., Bush, M. B., & Chapman, E. S. (2010). Perceptions of Competency Deficiencies in Engineering Graduates. Australasian Journal of Engineering Education, 16(1), 55-68. doi:10.1080/22054952.2010.11464039Mao, X., Zhang, X., & AbouRizk, S. M. (2009). Enhancing Value Engineering Process by Incorporating Inventive Problem-Solving Techniques. Journal of Construction Engineering and Management, 135(5), 416-424. doi:10.1061/(asce)co.1943-7862.0000001Mendelsohn, R. (1998). Teamwork—The Key to Productivity. Journal of Management in Engineering, 14(1), 22-25. doi:10.1061/(asce)0742-597x(1998)14:1(22)Moore, B. V. (1921). Personnel selection of graduate engineers: The differentiation of apprentice engineers for training as salesmen, designers, and executives of production. Psychological Monographs, 30(5), i-85. doi:10.1037/h0093191Moy, J. W., & Lee, S. M. (2002). The career choice of business graduates: SMEs or MNCs? Career Development International, 7(6), 339-347. doi:10.1108/13620430210444367Nair, C. S., Patil, A., & Mertova, P. (2009). Re-engineering graduate skills – a case study. European Journal of Engineering Education, 34(2), 131-139. doi:10.1080/03043790902829281Passow, H. J. (2012). Which ABET Competencies Do Engineering Graduates Find Most Important in their Work? Journal of Engineering Education, 101(1), 95-118. doi:10.1002/j.2168-9830.2012.tb00043.xPinnington, A. H. (2011). Competence development and career advancement in professional service firms. Personnel Review, 40(4), 443-465. doi:10.1108/00483481111133336Reio, T. G., & Sutton, F. C. (2006). Employer assessment of work-related competencies and workplace adaptation. Human Resource Development Quarterly, 17(3), 305-324. doi:10.1002/hrdq.1176Robar, T. Y. (1998). Communication and Career Advancement. Journal of Management in Engineering, 14(2), 26-28. doi:10.1061/(asce)0742-597x(1998)14:2(26)Rowold, J., & Kauffeld, S. (2008). Effects of career‐related continuous learning on competencies. Personnel Review, 38(1), 90-101. doi:10.1108/00483480910920732Ruiz-Mercader, J., Meroño-Cerdan, A. L., & Sabater-Sánchez, R. (2006). Information technology and learning: Their relationship and impact on organisational performance in small businesses. International Journal of Information Management, 26(1), 16-29. doi:10.1016/j.ijinfomgt.2005.10.003Soliman, F., & Spooner, K. (2000). Strategies for implementing knowledge management: role of human resources management. Journal of Knowledge Management, 4(4), 337-345. doi:10.1108/13673270010379894Srour, I., Abdul-Malak, M.-A., Itani, M., Bakshan, A., & Sidani, Y. (2013). Career Planning and Progression for Engineering Management Graduates: An Exploratory Study. Engineering Management Journal, 25(3), 85-100. doi:10.1080/10429247.2013.11431985Sunindijo, R. Y., Hadikusumo, B. H., & Ogunlana, S. (2007). Emotional Intelligence and Leadership Styles in Construction Project Management. Journal of Management in Engineering, 23(4), 166-170. doi:10.1061/(asce)0742-597x(2007)23:4(166)Tanova, C. (2003). Firm size and recruitment: staffing practices in small and large organisations in north Cyprus. Career Development International, 8(2), 107-114. doi:10.1108/13620430310465534Teichler, U. (1999). Higher education policy and the world of work: changing conditions and challenges. Higher Education Policy, 12(4), 285-312. doi:10.1016/s0952-8733(99)00019-7Tsang, M. C., & Levin, H. M. (1985). The economics of overeducation. Economics of Education Review, 4(2), 93-104. doi:10.1016/0272-7757(85)90051-2Ward, J. H. (1963). Hierarchical Grouping to Optimize an Objective Function. Journal of the American Statistical Association, 58(301), 236-244. doi:10.1080/01621459.1963.10500845Zenger, T. R. (1994). Explaining Organizational Diseconomies of Scale in R&D: Agency Problems and the Allocation of Engineering Talent, Ideas, and Effort by Firm Size. Management Science, 40(6), 708-729. doi:10.1287/mnsc.40.6.708Zenger, T. R., & Lazzarini, S. G. (2004). Compensating for innovation: Do small firms offer high-powered incentives that lure talent and motivate effort? Managerial and Decision Economics, 25(67), 329-345. doi:10.1002/mde.119

    The role of leadership in salespeople’s price negotiation behavior

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    Salespeople assume a key role in defending firms’ price levels in price negotiations with customers. The degree to which salespeople defend prices should critically depend upon their leaders’ influence. However, the influence of leadership on salespeople’s price defense behavior is barely understood, conceptually or empirically. Therefore, building on social learning theory, the authors propose that salespeople might adopt their leaders’ price defense behavior given a transformational leadership style. Furthermore, drawing on the contingency leadership perspective, the authors argue that this adoption fundamentally depends on three variables deduced from the motivation–ability–opportunity (MAO) framework, that is, salespeople’s learning motivation, negotiation efficacy, and perceived customer lenience. Results of a multi-level model using data from 92 salespeople and 264 salesperson–customer interactions confirm these predictions. The first to explore contingencies of salespeople’s adoption of their transformational leaders’ price negotiation behaviors, this study extends marketing theory and provides actionable guidance to practitioners
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