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.
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.
Testosterone and alendronate have been identified as two bone healing compounds which, when combined, synergistically stimulate bone regeneration. This study describes the development of a novel ...ultrasonic spray coating for sustained release of ancillary amounts of testosterone and alendronate encapsulated in PLGA 5004A as a carrier. Due to the low amounts of testosterone and alendronate used, sensitive in vitro assays were developed to determine in vitro release. The ultrasonic spray coating technology was optimized for coating titanium screws and pericardial collagen membranes, with the aim to improve osseo-integration and (guided) bone regeneration, respectively, without interfering with their primary mode of action. In vitro release analysis of collagen membranes and screws showed up to 21 days sustained release of the compounds without a burst release. Subsequent preclinical studies in rat and rabbit models indicated that testosterone and alendronate coated membranes and screws significantly improved bone regeneration in vivo. Coated membranes significantly improved the formation of new bone in a critical size calvarial defect model in rats (by 160% compared to controls). Coated screws implanted in rabbit femoral condyles significantly improved bone implant contact (69% vs 54% in controls), bone mineral density (121%) and bone volume (119%) up to 1.3 mm from the implant. Based on the results obtained, we suggest that implants or membranes enabled with local sustained delivery of ancillary amounts of testosterone and alendronate can be a promising system to stimulate local bone regeneration resulting in improved osseo-integration of implants and improved healing of bone defects and fractures.
The impact of body mass index (BMI) on survival in lymphoma remains controversial. We leveraged a prospective cohort of lymphoma patients enrolled to SPORE Molecular Epidemiology Resource between ...2002 and 2015 to assess the association of BMI before diagnosis, BMI at diagnosis, and BMI change over time with lymphoma-specific survival (LSS). A total of 4009 lymphoma patients (670 diffuse large B-cell lymphoma (DLBCL), 689 follicular lymphoma (FL), 1018 chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL), and 1632 other subtypes) were included. Significantly shorter LSS after diagnosis was observed for FL patients who were obese before diagnosis (HR: 3.02, 95%CI: 1.43-6.41, p=.004) and for those with a ≥ 5% increase in BMI from diagnosis to 3-year follow-up (HR: 3.53, 95%CI: 1.22-10.2, p=.020). In contrast, obesity prior to or at the time of diagnosis was not associated with LSS in DLBCL and CLL/SLL. The impact of weight control after diagnosis in FL patient warrants investigation.
In this study, the mechanical properties of an implanted calcium phosphate (CaP) cement incorporated with 20
wt% poly (
dl-lactic-
co-glycolic acid) (PLGA) microparticles were investigated in a rat ...cranial defect. After 2, 4 and 8 weeks of implantation, implants were evaluated mechanically (push-out test) and morphologically (Scanning Electron Microscopy (SEM) and histology). The results of the push-out test showed that after 2 weeks the shear strength of the implants was 0.44±0.44
MPa (average±sd), which increased to 1.34±1.05
MPa at 4 weeks and finally resulted in 2.60±2.78
MPa at 8 weeks. SEM examination showed a fracture plane at the bone–cement interface at 2 weeks, while the 4- and 8-week specimens created a fracture plane into the CaP/PLGA composites, indicating an increased strength of the bone–cement interface. Histological evaluation revealed that the two weeks implantation period resulted in minimal bone ingrowth, while at 4 weeks of implantation the peripheral PLGA microparticles were degraded and replaced by deposition of newly formed bone. Finally, after 8 weeks of implantation the degradation of the PLGA microparticles was almost completed, which was observed by the bone ingrowth throughout the CaP/PLGA composites.
On basis of our results, we conclude that the shear strength of the bone–cement interface increased over time due to bone ingrowth into the CaP/PLGA composites. Although the bone–cement contact could be optimized with an injectable CaP cement to enhance bone ingrowth, still the mechanical properties of the composites after 8 weeks of implantation are insufficient for load-bearing purposes.
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.
Partnerships between universities and industrial firms can play a key role in enhancing competitiveness because they provide a conduit for the spillover of knowledge from the academic organization ...where knowledge is created to the firm where it is transformed into innovative activity. We set forth in this paper a model of industry/university participation, and we test the model empirically, using research project data on entrepreneurial firms that were funded through the US Department of Energy's Small Business Innovation Research (SBIR) program. We find that larger firms are more likely to be involved in a research partnership with a university, in general, as are firms with founders who have an academic background. We find the latter result holds across disaggregated types of university partnerships, as well. We find no empirical evidence that the size of the SBIR award influences the likelihood of a research partnership.
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