The cytocompatibility and early osteogenic characteristics of an injectable calcium phosphate cement.

In this study, the cytocompatibility and early osteogenic characteristics of rat bone marrow cells (RBMCs) on injectable calcium phosphate (CaP) cement (Calcibon) were investigated. In addition to unmodified CaP cement discs, 2 other treatments were given to the discs: preincubation in MilliQ and sintering at different temperatures. After primary culture, RBMCs were dropwise seeded on the discs and cultured for 12 days. The samples were evaluated in terms of cell viability, morphology (live and dead assays and scanning electron microscopy (SEM)), cell proliferation (deoxyribonucleic acid (DNA) analyses), early cell differentiation (alkaline phosphatase (ALP) activity), and physicochemical analyses (xray diffraction (XRD)). The live and dead, DNA, and SEM results showed that Calcibon discs without any additional treatment were not supporting osteoblast-like cells in vitro. There were fewer cells, and cell layers were detached from the disc surface. Therefore, different preincubation periods and sintering temperatures were evaluated to improve the cytocompatibility of the CaP cement. Preincubating discs in MilliQ for periods of 1, 4, 8, and 12 weeks resulted in the hydrolysis of a-tri calcium phosphate (TCP) into an apatite-like structure with some b-TCP, as shown with XRD, but the material was not cytocompatible. Sintering the discs between 8008C and 11008C resulted in conversion of a-TCP to b-TCP with some hydroxyapatite and an increase in crystallinity. Eventually, the discs sintered at 11008C achieved better cell attachment, more-abundant cell proliferation, and earlier differentiation than other sintered (6008C, 8008C, and 10008C), preincubated, and unmodified specimens. On basis of our results, we conclude that in vivo results with CaP-based cements do not guarantee in vitro applicability. Furthermore, unmodified Calcibon is not cytocompatible in vitro, although preincubation of the material results in a more-favorable cell response, sintering of the material at 11008C results in the best osteogenic properties. In contrast to in vivo studies, the Calcibon CaP cement is not suitable as a scaffold for cellbased tissue-engineering strategies

The effects of governmental financing on firms' R&D activities: a theoretical and empirical investigation

There is a long history of governmental support for private innovative activity in the U.S.A. However, the economic research on this topic has been narrow in focus, emphasizing primarily the relationship between the level of governmental R&D and the corresponding (in a causal sense) level of private R&D. In this paper, we explore the effects of governmental financing on another aspect of private innovative behavior—the sharing by firms of innovation-related knowledge. Based on a simple model of private innovative activity in the face of an exogenous governmental R&D contracts/grants structure, we find, among other things, that governmental R&D allocations spur industrial R&D laboratories toward greater sharing of their innovation-related knowledge

Research risk and public policy in a knowledge-based economy: the relative research efficiency of government versus university labs

This paper contributes to the burgeoning literature about the knowledge economy by addressing the question of which intellectual-based institutions in an economy contribute the greatest amount to economic growth. In particular, we posit a theoretical model that compares the research efficiency of government research labs to university research labs. We conclude that there is merit in shifting public moneys from government research labs to university research labs from an efficiency perspective. This result opens the door for empirical research on relative research efficiencies and the implications for efficiency gains on economic growth

Knowledge spillovers, collective entrepreneurship, and economic growth: the role of universities

To improve our understanding of the role that universities play in facilitating the transmission of knowledge to private-sector business enterprises so as to generate economic growth, this article builds on the Knowledge Spillover Theory of Entrepreneurship to develop a formal model of university-with-business enterprise collaborative research partnerships in which the outcome is both mutually desirable and feasible. This model shows that if a university seeks to act as a complement to private-sector collaborative R&D so that it will be attractive to both incumbent firms and startup entrepreneurs, it needs to structure its program so that business enterprise revenues increase and business enterprise R&D costs rise by a smaller proportion than revenues increase, if they rise at all (and a fall would be better). Such a structure is consistent with both business enterprise and university interests, but is only likely to be feasible if the university is subsidized to cover the cost of such public-private collaborative research partnerships. In the absence of such support, the university will have to cover its costs through a fee charged to participating business enterprises and that will result in the university being seen as a substitute rather than a complement to private-sector collaborative R&D, and thus the university will be seen as an unattractive partner for many business enterprises

Regional Appropriation of University-Based Knowledge and Technology for Economic Development

Economic development practitioners and scholars recognize the link between universities and regional economic development. It is predicated on the spillover of knowledge from universities to commercialization. The literature has focused on the supply side, which involves university research and technology transfer mechanisms. We examine the role played by the demand for university-based knowledge and university-developed technology. We identify links between businesses and the university as a key conduit facilitating the spillover of knowledge using data on the Department of Energy’s Small Business Innovation Research (SBIR) program. We provide supply-side evidence on university research relationships and how the use of knowledge and technologies that flow from a university affect economic growth. We identify the role that SBIR-funded businesses play in the spillover of knowledge from the creating organization to where that knowledge is used and commercialized. Our results suggest that knowledge is systematically transmitted through university-related research

A theoretical analysis of the role of social networks in entrepreneurship

Entrepreneurship involves innovation and uncertainty. We outline a theory of entrepreneurship, which highlights the importance of social networks in promoting innovation and reducing uncertainty. Our findings suggest that this “social” aspect of entrepreneurship increases the probability of entrepreneurial success. The results also lend credence to theories of entrepreneurship that suggest that entrepreneurial opportunities are formed endogenously by the entrepreneurs who create them. We also consider the public policy implications of our findings

A Theoretical and Empirical Analysis of the Decision to Locate on a University Research Park

University research parks constitute a potentially important mechanism for university technology transfer and regional economic development. Unfortunately, there is little theoretical and empirical evidence on the firm-level choice decision to locate on such a facility. We fill this gap by outlining and testing a theoretical model of this selection process. Our empirical results suggest that firms locating on university research park are more research active and more diversified than observationally equivalent firms

Toward a theory of the entrepreneurial process

This paper models the entrepreneurial process as both creation and discovery composed of an iterative two-step process where entrepreneurs create social networks based on subjective expectations about the future effectiveness of those networks, and then choose the innovation to pursue and map a search process to discover how to bring the innovation to fruition. Critical to this process is the mix of strong ties and weak ties that make up social networks and the ability to carry forward the social capital embodied in such networks. The tendency of long-existing entrepreneurs to be less innovative can be explained using this model

Privatization, bureaucracy, and risk aversion

The role of governmental risk aversion in the decision to privatize the production of goods and services has not been examined closely. Using a model of a risk-averse, single-service Niskanen bureaucrat, we determine the conditions under which a bureaucrat will prefer to privatize rather than produce in-house. If the private-sector firm is risk neutral, the result will be a fixed-fee contract with complete insurance. If the private-sector firm is risk averse, the result will be a cost-plus contract with the degree of cost sharing determined by the bureaucrat's share of total risk aversion. In both cases, the bureaucrat's sponsor may affect the likelihood of privatization by manipulating the rewards and penalties imposed on the bureaucrat

Why are governmental R&D and private R&D complements? (research and development).

It is well known that governmental R&D and private R&D have complementary relationship. However, no previous study has provided an explanation for why that complementary relationship exists. This paper argues that infratechnology is the critical link between governmental and private R&D and that the observed complementarity is the result of technical complementarity at the production level between funding, infratechnology, and knowledge sharing. A theoretical framework based on this argument is developed and examined empirically for supporting evidence. Evidence of technical complementarity is found as well as evidence that governmental R&D stimulates the sharing of knowledge